From 44bbfc3a761332e46724af409b7a6e584b4b02be Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From d31a2453bc19ca62717299e95376b56652f9473e Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From 3b9f47061ae1310b4f04e4a81e466b5c68ee3986 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From f66bc754d201d965730c278d79d8d094270c0aea Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From 86e63ba6128e7ad7a072b6f7c9a8b671ef4200c1 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 9b5de603750d9a2e3a85092e29d3816f8a7aaefe Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 5545379812427992b38ef46ac72a332565a0212a Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From 1585cb3c2848d639b692e8424287aa8bebfcbc28 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From eb3a6ea51832d13b5eb1032148d9f83ae6ebb9b9 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 445e6a12c360c52ac1c0c46c89ab59d9d77c1195 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..4a743ba 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From 3d47992707e37c88c759dd58574acf33c790db34 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From e2f966603013af49cee134c77eccb8380e92d324 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From cc2140108ca0b1dbaa05f6caf45ec0c155311fff Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 145173f0fe7edcc0fb53b6d52e3e943f8ea0a6fb Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 359ad299e3c526a6583c95c1af938b1fac579c6b Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From 4f3e06e7f821f70a0416bb4fed92cf3c9c81de85 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From f5b1677f5aea806344a8c3a135afa9c24f35ea7b Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 025212d4fee67c77a8f7cf3a9b5f423850b553a2 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 16 Jan 2020 17:04:35 +0100
Subject: sys_linux: allow renameat2 in seccomp filter

This is needed for architectures that support neither rename() nor
renameat() (e.g. riscv64)


Gbp-Pq: Name allow-renameat2-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..ffbc9dd 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -493,8 +493,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(chown32), SCMP_SYS(faccessat), SCMP_SYS(fchmodat), SCMP_SYS(fchownat),
     SCMP_SYS(fstat), SCMP_SYS(fstat64), SCMP_SYS(getdents), SCMP_SYS(getdents64),
     SCMP_SYS(lseek), SCMP_SYS(newfstatat), SCMP_SYS(rename), SCMP_SYS(renameat),
-    SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs), SCMP_SYS(statfs64),
-    SCMP_SYS(unlink), SCMP_SYS(unlinkat),
+    SCMP_SYS(renameat2), SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs),
+    SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
     SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
-- 
cgit v1.2.3


From d13ed613924ef496f52ca917eae8fe20684c4b83 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ffbc9dd..ee7ddc1 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From 7486eca1e3ea39ef0af3e950d504e8141e767c20 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From 7fd207b94282444ac710408365abded4eac6adaf Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From a0caa17e57a06e1a20daa9fd109986823d33fa2c Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 817d29420d94d956b10a2d31cfc91f0ee18adf2e Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 5b6948c0bf14fcda499250da1f63403ffcd3c87e Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From ef445330c712564c68b10fdc730e54b6fedf3840 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From d07c50f170898d714415fcf355ba3bed23b633ad Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 66260f6e750b919e8a1eb1c1811f678e1f4e4d28 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 16 Jan 2020 17:04:35 +0100
Subject: sys_linux: allow renameat2 in seccomp filter

This is needed for architectures that support neither rename() nor
renameat() (e.g. riscv64)


Gbp-Pq: Name allow-renameat2-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..ffbc9dd 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -493,8 +493,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(chown32), SCMP_SYS(faccessat), SCMP_SYS(fchmodat), SCMP_SYS(fchownat),
     SCMP_SYS(fstat), SCMP_SYS(fstat64), SCMP_SYS(getdents), SCMP_SYS(getdents64),
     SCMP_SYS(lseek), SCMP_SYS(newfstatat), SCMP_SYS(rename), SCMP_SYS(renameat),
-    SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs), SCMP_SYS(statfs64),
-    SCMP_SYS(unlink), SCMP_SYS(unlinkat),
+    SCMP_SYS(renameat2), SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs),
+    SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
     SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
-- 
cgit v1.2.3


From 3f905d4b5543ff43dccde02368299361e25312b5 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ffbc9dd..ee7ddc1 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From f41a777a53542219611500d53ef4e9c63394922a Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From d7ff44d7feac74eef58fd2b89bb2531c0dd35087 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From 93e6ebb126d0e1b81914e350210e1b09c3e3f295 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 13da0b62b52f8bceafed70f7d52562c01614a989 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 2c9a18beb8d1fc261d99045500adf137b8ebcd3e Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From 2a5c3283114af06e2a4d4a1885bd98cf993b82c1 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From 5eb954cc4b8182426741292050e355677bcc621b Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 0c9ea3e3dce1d6818b6e1bff6b57c1a93ed5b642 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 16 Jan 2020 17:04:35 +0100
Subject: sys_linux: allow renameat2 in seccomp filter

This is needed for architectures that support neither rename() nor
renameat() (e.g. riscv64)


Gbp-Pq: Name allow-renameat2-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..ffbc9dd 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -493,8 +493,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(chown32), SCMP_SYS(faccessat), SCMP_SYS(fchmodat), SCMP_SYS(fchownat),
     SCMP_SYS(fstat), SCMP_SYS(fstat64), SCMP_SYS(getdents), SCMP_SYS(getdents64),
     SCMP_SYS(lseek), SCMP_SYS(newfstatat), SCMP_SYS(rename), SCMP_SYS(renameat),
-    SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs), SCMP_SYS(statfs64),
-    SCMP_SYS(unlink), SCMP_SYS(unlinkat),
+    SCMP_SYS(renameat2), SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs),
+    SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
     SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
-- 
cgit v1.2.3


From 5cdafedb62634223be0cacb3ca556cb16a40c6a1 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ffbc9dd..ee7ddc1 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From e5870485ae58b42093f43e10021fa1d7f9cf7494 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From 676e0fc1642fee103d62b0c326fa61173b7fb744 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From 0bcfc59bb84a63cfc454027d98fbd4fdb9658af6 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 803f856c5af0300a4bd5e100442ec7542435088e Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 2c2cbef8935f5b30e44d986d5b3fa74b46af3a06 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From 5e1af24a62252a08770a89fb172c43a5ff7d6089 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From 234358e0d64290bb5a3f8eaffb0a484b0f28c316 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From ad2b1605261d779dbf40b7043bac040e9a743e0d Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Tue, 19 May 2020 16:42:18 +0200
Subject: allow some *time64 syscalls in seccomp filter

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/chrony/+bug/1878005
Forwarded: https://www.mail-archive.com/chrony-dev@chrony.tuxfamily.org/msg02172.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=7a7295992f76def739f0110f1e8f1346ff3a032e
Last-Update: 2020-05-18

Allowing these system calls is required for 32-bit architectures with new
system calls using 64-bit time_t.
Last-Update: 2020-05-18
Gbp-Pq: Name allow-some-*time64-syscalls-in-seccomp-filter.patch
---
 sys_linux.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ee7ddc1..931dd95 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,7 +478,14 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime),
+#ifdef __NR_clock_adjtime64
+    SCMP_SYS(clock_adjtime64),
+#endif
+    SCMP_SYS(clock_gettime),
+#ifdef __NR_clock_gettime64
+    SCMP_SYS(clock_gettime64),
+#endif
     SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
@@ -497,14 +504,29 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
-    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
+    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg),
+#ifdef __NR_recvmmsg_time64
+    SCMP_SYS(recvmmsg_time64),
+#endif
+    SCMP_SYS(recvmsg),
     SCMP_SYS(send), SCMP_SYS(sendmmsg), SCMP_SYS(sendmsg), SCMP_SYS(sendto),
     /* TODO: check socketcall arguments */
     SCMP_SYS(socketcall),
     /* General I/O */
     SCMP_SYS(_newselect), SCMP_SYS(close), SCMP_SYS(open), SCMP_SYS(openat), SCMP_SYS(pipe),
-    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll), SCMP_SYS(pselect6), SCMP_SYS(read),
-    SCMP_SYS(futex), SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
+    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll),
+#ifdef __NR_ppoll_time64
+    SCMP_SYS(ppoll_time64),
+#endif
+    SCMP_SYS(pselect6),
+#ifdef __NR_pselect6_time64
+    SCMP_SYS(pselect6_time64),
+#endif
+    SCMP_SYS(read), SCMP_SYS(futex),
+#ifdef __NR_futex_time64
+    SCMP_SYS(futex_time64),
+#endif
+    SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
     /* Miscellaneous */
     SCMP_SYS(getrandom), SCMP_SYS(sysinfo), SCMP_SYS(uname),
   };
-- 
cgit v1.2.3


From bd16a78b97c6cd9538ac951a88f447308eac7dc2 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 16 Jan 2020 17:04:35 +0100
Subject: sys_linux: allow renameat2 in seccomp filter

This is needed for architectures that support neither rename() nor
renameat() (e.g. riscv64)


Gbp-Pq: Name allow-renameat2-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..ffbc9dd 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -493,8 +493,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(chown32), SCMP_SYS(faccessat), SCMP_SYS(fchmodat), SCMP_SYS(fchownat),
     SCMP_SYS(fstat), SCMP_SYS(fstat64), SCMP_SYS(getdents), SCMP_SYS(getdents64),
     SCMP_SYS(lseek), SCMP_SYS(newfstatat), SCMP_SYS(rename), SCMP_SYS(renameat),
-    SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs), SCMP_SYS(statfs64),
-    SCMP_SYS(unlink), SCMP_SYS(unlinkat),
+    SCMP_SYS(renameat2), SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs),
+    SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
     SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
-- 
cgit v1.2.3


From 0a492d6d9b298269a641603fc430487c955add27 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ffbc9dd..ee7ddc1 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From 7af939955fa2d3e4e86ddda359afc8fed3f51b72 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From 773362c5f07ffd5f8eab018cce076ce24e61b261 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From 1e2687c9892b75536dec3f0556beb65503e3635d Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 979e056fce3dc21d2933e6396cdeb5503c628b0d Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From 3e128f9b669b598099536bc375ce443122bc0926 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From ecc9bbd66d94257564f56039d09589834618a5c8 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From fd5d3387fad02a9439066a4bfffd7ce29f4a6dd8 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 98e96b55cc097d93a487319eef5d346021a2f9a1 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 20 Aug 2020 14:07:22 +0200
Subject: allow some *time64 syscalls in seccomp filter

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/chrony/+bug/1878005
Forwarded: https://www.mail-archive.com/chrony-dev@chrony.tuxfamily.org/msg02172.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=7a7295992f76def739f0110f1e8f1346ff3a032e
Last-Update: 2020-05-18

Allowing these system calls is required for 32-bit architectures with new
system calls using 64-bit time_t.
Last-Update: 2020-05-18
Gbp-Pq: Name allow-some-*time64-syscalls-in-seccomp-filter.patch
---
 sys_linux.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ee7ddc1..931dd95 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,7 +478,14 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime),
+#ifdef __NR_clock_adjtime64
+    SCMP_SYS(clock_adjtime64),
+#endif
+    SCMP_SYS(clock_gettime),
+#ifdef __NR_clock_gettime64
+    SCMP_SYS(clock_gettime64),
+#endif
     SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
@@ -497,14 +504,29 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
-    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
+    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg),
+#ifdef __NR_recvmmsg_time64
+    SCMP_SYS(recvmmsg_time64),
+#endif
+    SCMP_SYS(recvmsg),
     SCMP_SYS(send), SCMP_SYS(sendmmsg), SCMP_SYS(sendmsg), SCMP_SYS(sendto),
     /* TODO: check socketcall arguments */
     SCMP_SYS(socketcall),
     /* General I/O */
     SCMP_SYS(_newselect), SCMP_SYS(close), SCMP_SYS(open), SCMP_SYS(openat), SCMP_SYS(pipe),
-    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll), SCMP_SYS(pselect6), SCMP_SYS(read),
-    SCMP_SYS(futex), SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
+    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll),
+#ifdef __NR_ppoll_time64
+    SCMP_SYS(ppoll_time64),
+#endif
+    SCMP_SYS(pselect6),
+#ifdef __NR_pselect6_time64
+    SCMP_SYS(pselect6_time64),
+#endif
+    SCMP_SYS(read), SCMP_SYS(futex),
+#ifdef __NR_futex_time64
+    SCMP_SYS(futex_time64),
+#endif
+    SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
     /* Miscellaneous */
     SCMP_SYS(getrandom), SCMP_SYS(sysinfo), SCMP_SYS(uname),
   };
-- 
cgit v1.2.3


From 73679851780ce6cbae2b039d2eeee3fa5de0b099 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 16 Jan 2020 17:04:35 +0100
Subject: sys_linux: allow renameat2 in seccomp filter

This is needed for architectures that support neither rename() nor
renameat() (e.g. riscv64)


Gbp-Pq: Name allow-renameat2-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 898dc7a..ffbc9dd 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -493,8 +493,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(chown32), SCMP_SYS(faccessat), SCMP_SYS(fchmodat), SCMP_SYS(fchownat),
     SCMP_SYS(fstat), SCMP_SYS(fstat64), SCMP_SYS(getdents), SCMP_SYS(getdents64),
     SCMP_SYS(lseek), SCMP_SYS(newfstatat), SCMP_SYS(rename), SCMP_SYS(renameat),
-    SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs), SCMP_SYS(statfs64),
-    SCMP_SYS(unlink), SCMP_SYS(unlinkat),
+    SCMP_SYS(renameat2), SCMP_SYS(stat), SCMP_SYS(stat64), SCMP_SYS(statfs),
+    SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
     SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
-- 
cgit v1.2.3


From 18729e12ace62b79d6598edb4b740d371349a8fe Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 2 Dec 2019 12:47:13 +0100
Subject: sys_linux: allow clock_adjtime in seccomp filter

The adjtimex() function in glibc was switched to the clock_adjtime
system call.


Gbp-Pq: Name allow-clock_adjtime-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ffbc9dd..ee7ddc1 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,8 +478,8 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_gettime), SCMP_SYS(gettimeofday),
-    SCMP_SYS(settimeofday), SCMP_SYS(time),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
     SCMP_SYS(getrlimit), SCMP_SYS(rt_sigaction), SCMP_SYS(rt_sigreturn),
-- 
cgit v1.2.3


From 5773c81bc01f4038a2087be9e7c907f6a6aa3b6a Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 18 Jun 2019 15:41:50 +0200
Subject: test: update processing of packet log

Two new fields have been added to the packet log, which broke some
of the simulation tests.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=62d6aed6a64b887c9e3b7f03d9e0db1deaa2696a

Gbp-Pq: Name update_processing_of_packet_log.patch
---
 test/simulation/test.common | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/test.common b/test/simulation/test.common
index 951a794..8ed6ad9 100644
--- a/test/simulation/test.common
+++ b/test/simulation/test.common
@@ -391,9 +391,9 @@ check_packet_port() {
 	for i in $(seq 1 $(get_chronyd_nodes)); do
 		test_message 3 0 "node $i:"
 
-		grep -E -q "	$port	[0-9]+\$" tmp/log.packets && \
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
 			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
-			grep -E -q -v "	$port	[0-9]+\$" && \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
 			test_ok || test_bad
 		[ $? -eq 0 ] || ret=1
 	done
-- 
cgit v1.2.3


From 13c8cbb750d1d041ed554fbddf9ff677901bd708 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:40:44 +0100
Subject: rtc: simplify and move switch_interrupts()

Gbp-Pq: Name rtc-simplify-and-move-switch_interrupts-function.patch
---
 rtc_linux.c | 37 ++++++++++++++-----------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index d4d9bd0..30833e5 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -527,6 +527,20 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
   return RTC_ST_OK;
 }
 
+/* ================================================== */
+
+static void
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+}
 
 /* ================================================== */
 /* file_name is the name of the file where we save the RTC params
@@ -603,29 +617,6 @@ RTC_Linux_Finalise(void)
 
 /* ================================================== */
 
-static void
-switch_interrupts(int onoff)
-{
-  int status;
-
-  if (onoff) {
-    status = ioctl(fd, RTC_UIE_ON, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "enable", strerror(errno));
-      return;
-    }
-    skip_interrupts = 1;
-  } else {
-    status = ioctl(fd, RTC_UIE_OFF, 0);
-    if (status < 0) {
-      LOG(LOGS_ERR, "Could not %s RTC interrupt : %s", "disable", strerror(errno));
-      return;
-    }
-  }
-}    
-
-/* ================================================== */
-
 static void
 measurement_timeout(void *any)
 {
-- 
cgit v1.2.3


From 0e9c58cb6e717c19e39bda91021cea80e453d275 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:30:42 +0100
Subject: rtc: don't finalize driver if initialization failed

Gbp-Pq: Name rtc-do-not-finalize-driver-if-initialization-failed.patch
---
 rtc.c       |  2 +-
 rtc_linux.c | 23 +++++++++++------------
 2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rtc.c b/rtc.c
index 33d04bf..fa83173 100644
--- a/rtc.c
+++ b/rtc.c
@@ -160,7 +160,7 @@ RTC_Initialise(int initial_set)
 void
 RTC_Finalise(void)
 {
-  if (driver.fini) {
+  if (driver_initialised) {
     (driver.fini)();
   }
 }
diff --git a/rtc_linux.c b/rtc_linux.c
index 30833e5..c1a705d 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -550,6 +550,17 @@ switch_interrupts(int on_off)
 int
 RTC_Linux_Initialise(void)
 {
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
   rtc_sec = MallocArray(time_t, MAX_SAMPLES);
   rtc_trim = MallocArray(double, MAX_SAMPLES);
   system_times = MallocArray(struct timespec, MAX_SAMPLES);
@@ -560,18 +571,6 @@ RTC_Linux_Initialise(void)
   /* In case it didn't get done by pre-init */
   coefs_file_name = CNF_GetRtcFile();
 
-  /* Try to open device */
-
-  fd = open (CNF_GetRtcDevice(), O_RDWR);
-  if (fd < 0) {
-    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
-        CNF_GetRtcDevice(), strerror(errno));
-    return 0;
-  }
-
-  /* Close on exec */
-  UTI_FdSetCloexec(fd);
-
   n_samples = 0;
   n_samples_since_regression = 0;
   n_runs = 0;
-- 
cgit v1.2.3


From 8c2fda5816fadd78e981665e9437552199d5319f Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:33:17 +0100
Subject: rtc: handle RTCs that don't support interrupts

Some RTCs supported by the Linux kernel don't support the RTC_UIE_ON/OFF
ioctls, which causes chronyd started with the -s option to get stuck in
the initial RTC mode.

After opening the RTC device in the initialization, return error if
the ioctls are not supported to prevent the upper layer from calling the
time_init() function and expecting it to finish.


Gbp-Pq: Name rtc-handle-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index c1a705d..8b21394 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -529,17 +529,19 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
 
 /* ================================================== */
 
-static void
+static int
 switch_interrupts(int on_off)
 {
   if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
     LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
         on_off ? "enable" : "disable", strerror(errno));
-    return;
+    return 0;
   }
 
   if (on_off)
     skip_interrupts = 1;
+
+  return 1;
 }
 
 /* ================================================== */
@@ -558,6 +560,12 @@ RTC_Linux_Initialise(void)
     return 0;
   }
 
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
   /* Close on exec */
   UTI_FdSetCloexec(fd);
 
-- 
cgit v1.2.3


From cf224248b47dee8fe24ba334c72ecba3f0fcaa30 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Dec 2019 17:42:34 +0100
Subject: rtc: disable interrupts in finalization

Don't leave interrupts enabled if chronyd is stopped when making an RTC
measurement.


Gbp-Pq: Name rtc-disable-interrupts-in-finalization.patch
---
 rtc_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtc_linux.c b/rtc_linux.c
index 8b21394..7ec27c9 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -611,6 +611,7 @@ RTC_Linux_Finalise(void)
   /* Remove input file handler */
   if (fd >= 0) {
     SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
     close(fd);
 
     /* Save the RTC data */
-- 
cgit v1.2.3


From 0f2f380b92c9c4100359395436b389763dbdc31a Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:40 +0100
Subject: rtc: extend check for RTCs that don't support interrupts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Several RTCs would only expose the broken behavior on enabling
interrupts. The reason for that is that the kernel only returns the
error if the state changes. Therefore the check has to probe
switch_interrupts(1) as well.

On platforms that work it will be switched on and off, while on those it
never works it will just stay off.

Clocks known to expose that behavior include, but are not limited to:
PPC64# dmesg | grep -i rtc   
[    0.241872] rtc-generic rtc-generic: registered as rtc0
[    0.270221] rtc-generic rtc-generic: setting system clock to ...
ARM64# dmesg | grep -i rtc
[    0.876198] rtc-efi rtc-efi: registered as rtc0
[    1.046869] rtc-efi rtc-efi: setting system clock to ...

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name rtc-extend-check-for-RTCs-that-do-not-support-interrupts.patch
---
 rtc_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rtc_linux.c b/rtc_linux.c
index 7ec27c9..3220fad 100644
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -561,7 +561,7 @@ RTC_Linux_Initialise(void)
   }
 
   /* Make sure the RTC supports interrupts */
-  if (!switch_interrupts(0)) {
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
     close(fd);
     return 0;
   }
-- 
cgit v1.2.3


From 6b1fdb146f5ddc94663996e95310260934f5a6e8 Mon Sep 17 00:00:00 2001
From: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Date: Thu, 12 Dec 2019 12:06:39 +0100
Subject: test: accept test result if RTC can't enable RTC_UIE_ON

The test might run on different platforms. If the platform happens
to have a RTC that does exist but unable to have RTC_UIE_ON set the
test will fail, while the chrony code is actually good.

Examples of bad clocks are:
- ppc64el: rtc-generic
- arm64: rtc-efi

To avoid that extend the log message check on 101-rtc to accept
that condition as a valid test result as well.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name test-accept-test-result-if-RTC-can-not-enable-RTC_UIE_ON.patch
---
 test/system/101-rtc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/system/101-rtc b/test/system/101-rtc
index fa9a70d..68bce68 100755
--- a/test/system/101-rtc
+++ b/test/system/101-rtc
@@ -14,6 +14,6 @@ echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
 
 start_chronyd || test_fail
 stop_chronyd || test_fail
-check_chronyd_message_count "\(clock off from RTC\|RTC time before last\)" 1 1 || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
 
 test_pass
-- 
cgit v1.2.3


From 0aad9f271c9eb1b66f12af8072c920f8c438f134 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 16 Sep 2020 12:32:23 +0200
Subject: allow some *time64 syscalls in seccomp filter

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/chrony/+bug/1878005
Forwarded: https://www.mail-archive.com/chrony-dev@chrony.tuxfamily.org/msg02172.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=7a7295992f76def739f0110f1e8f1346ff3a032e
Last-Update: 2020-05-18

Allowing these system calls is required for 32-bit architectures with new
system calls using 64-bit time_t.
Last-Update: 2020-05-18
Gbp-Pq: Name allow-some-*time64-syscalls-in-seccomp-filter.patch
---
 sys_linux.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index ee7ddc1..931dd95 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -478,7 +478,14 @@ SYS_Linux_EnableSystemCallFilter(int level)
 {
   const int syscalls[] = {
     /* Clock */
-    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime), SCMP_SYS(clock_gettime),
+    SCMP_SYS(adjtimex), SCMP_SYS(clock_adjtime),
+#ifdef __NR_clock_adjtime64
+    SCMP_SYS(clock_adjtime64),
+#endif
+    SCMP_SYS(clock_gettime),
+#ifdef __NR_clock_gettime64
+    SCMP_SYS(clock_gettime64),
+#endif
     SCMP_SYS(gettimeofday), SCMP_SYS(settimeofday), SCMP_SYS(time),
     /* Process */
     SCMP_SYS(clone), SCMP_SYS(exit), SCMP_SYS(exit_group), SCMP_SYS(getpid),
@@ -497,14 +504,29 @@ SYS_Linux_EnableSystemCallFilter(int level)
     SCMP_SYS(statfs64), SCMP_SYS(unlink), SCMP_SYS(unlinkat),
     /* Socket */
     SCMP_SYS(bind), SCMP_SYS(connect), SCMP_SYS(getsockname), SCMP_SYS(getsockopt),
-    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg), SCMP_SYS(recvmsg),
+    SCMP_SYS(recv), SCMP_SYS(recvfrom), SCMP_SYS(recvmmsg),
+#ifdef __NR_recvmmsg_time64
+    SCMP_SYS(recvmmsg_time64),
+#endif
+    SCMP_SYS(recvmsg),
     SCMP_SYS(send), SCMP_SYS(sendmmsg), SCMP_SYS(sendmsg), SCMP_SYS(sendto),
     /* TODO: check socketcall arguments */
     SCMP_SYS(socketcall),
     /* General I/O */
     SCMP_SYS(_newselect), SCMP_SYS(close), SCMP_SYS(open), SCMP_SYS(openat), SCMP_SYS(pipe),
-    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll), SCMP_SYS(pselect6), SCMP_SYS(read),
-    SCMP_SYS(futex), SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
+    SCMP_SYS(pipe2), SCMP_SYS(poll), SCMP_SYS(ppoll),
+#ifdef __NR_ppoll_time64
+    SCMP_SYS(ppoll_time64),
+#endif
+    SCMP_SYS(pselect6),
+#ifdef __NR_pselect6_time64
+    SCMP_SYS(pselect6_time64),
+#endif
+    SCMP_SYS(read), SCMP_SYS(futex),
+#ifdef __NR_futex_time64
+    SCMP_SYS(futex_time64),
+#endif
+    SCMP_SYS(select), SCMP_SYS(set_robust_list), SCMP_SYS(write),
     /* Miscellaneous */
     SCMP_SYS(getrandom), SCMP_SYS(sysinfo), SCMP_SYS(uname),
   };
-- 
cgit v1.2.3


From 97d0a1614696b4dfb9318cc3657708cef2677fca Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Tue, 13 Oct 2020 15:59:33 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From f12969fbd45c2ba281423068b1d58a42fe23ae67 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Mon, 18 Jan 2021 21:58:52 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 4523daf0c535009d06d4714bab8e03bdba81b8c5 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 21 Jan 2021 20:02:39 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From aa767d80fc93b1d140247a2b388a5b0a1c3ca145 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 4 Feb 2021 19:49:22 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 6360a9408ab1b9d8aa3928693191c359378a92b8 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Sun, 21 Feb 2021 21:59:22 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 4fd14c17bc57dc6ea45c648f0fc7c10ee8613416 Mon Sep 17 00:00:00 2001
From: Foster Snowhill <forst@forstwoof.ru>
Date: Sun, 4 Apr 2021 15:12:17 +0200
Subject: sys_linux: allow setsockopt(SOL_IP, IP_TOS) in seccomp

This system call is required by the DSCP marking feature introduced in commit
6a5665ca5877 ("conf: add dscp directive").

Before this change, enabling seccomp filtering (chronyd -F 1) and specifying a
custom DSCP value in the configuration (for example "dscp 46") caused the
process to be killed by seccomp due to IP_TOS not being allowed by the filter.

Tested before and after the change on Ubuntu 21.04, kernel 5.11.0-13-generic.
IP_TOS is available since Linux 1.0, so I didn't add any ifdefs for it.

Signed-off-by: Foster Snowhill <forst@forstwoof.ru>

Bug: https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2021/04/msg00000.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=966e6fd939df724235a93e7a89dd7cf67178f99d
Last-Update: 2021-04-08

Gbp-Pq: Name allow-IP_TOS-socket-option-in-seccomp-filter.patch
---
 sys_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys_linux.c b/sys_linux.c
index 0b24445..11fc1ff 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -615,7 +615,7 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
   };
 
   const static int socket_options[][2] = {
-    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND },
+    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND }, { SOL_IP, IP_TOS },
 #ifdef FEAT_IPV6
     { SOL_IPV6, IPV6_V6ONLY }, { SOL_IPV6, IPV6_RECVPKTINFO },
 #endif
-- 
cgit v1.2.3


From a1e05c311a4224e9f6add60852fe21f66997f9c6 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 8 Apr 2021 16:21:16 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 9a36f6bc3ce3cac41f5ae4678f7cd47a741a9dfb Mon Sep 17 00:00:00 2001
From: Foster Snowhill <forst@forstwoof.ru>
Date: Sun, 4 Apr 2021 15:12:17 +0200
Subject: sys_linux: allow setsockopt(SOL_IP, IP_TOS) in seccomp

This system call is required by the DSCP marking feature introduced in commit
6a5665ca5877 ("conf: add dscp directive").

Before this change, enabling seccomp filtering (chronyd -F 1) and specifying a
custom DSCP value in the configuration (for example "dscp 46") caused the
process to be killed by seccomp due to IP_TOS not being allowed by the filter.

Tested before and after the change on Ubuntu 21.04, kernel 5.11.0-13-generic.
IP_TOS is available since Linux 1.0, so I didn't add any ifdefs for it.

Signed-off-by: Foster Snowhill <forst@forstwoof.ru>

Bug: https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2021/04/msg00000.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=966e6fd939df724235a93e7a89dd7cf67178f99d
Last-Update: 2021-04-08

Gbp-Pq: Name allow-IP_TOS-socket-option-in-seccomp-filter.patch
---
 sys_linux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys_linux.c b/sys_linux.c
index 0b24445..11fc1ff 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -615,7 +615,7 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
   };
 
   const static int socket_options[][2] = {
-    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND },
+    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND }, { SOL_IP, IP_TOS },
 #ifdef FEAT_IPV6
     { SOL_IPV6, IPV6_V6ONLY }, { SOL_IPV6, IPV6_RECVPKTINFO },
 #endif
-- 
cgit v1.2.3


From 25008cddf7ca59365bb0953951cf55ec5bf898db Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 13 May 2021 16:51:41 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 48e0dbcda8ba7f9eb0f6198e7e829d1daf04bb6c Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 29 Apr 2021 12:35:49 +0200
Subject: sys_linux: allow BINDTODEVICE option in seccomp filter

Fixes: 4ef944b73436 ("socket: add support for binding sockets to device")

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=b9f5ce83b02e765ad5a65a264e88352528d6b2b3
Last-Update: 2021-05-13

Gbp-Pq: Name allow-BINDTODEVICE-option-in-seccomp-filter.patch
---
 sys_linux.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys_linux.c b/sys_linux.c
index 11fc1ff..23d4317 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -618,6 +618,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
     { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND }, { SOL_IP, IP_TOS },
 #ifdef FEAT_IPV6
     { SOL_IPV6, IPV6_V6ONLY }, { SOL_IPV6, IPV6_RECVPKTINFO },
+#endif
+#ifdef SO_BINDTODEVICE
+    { SOL_SOCKET, SO_BINDTODEVICE },
 #endif
     { SOL_SOCKET, SO_BROADCAST }, { SOL_SOCKET, SO_REUSEADDR },
 #ifdef SO_REUSEPORT
-- 
cgit v1.2.3


From e2d503b8ae2e714f0e7520f6ace3a0e2982e13a7 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 29 Apr 2021 16:53:40 +0200
Subject: sys_linux: allow getuid32 in seccomp filter

This was triggered on x86 in an NTS test.

Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=9cdfc15e310887d86c74beb0d6b748572624201c
Last-Update: 2021-05-13

Gbp-Pq: Name allow-getuid32-in-seccomp-filter.patch
---
 sys_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys_linux.c b/sys_linux.c
index 23d4317..80cd31b 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -508,6 +508,7 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
     SCMP_SYS(getpid),
     SCMP_SYS(getrlimit),
     SCMP_SYS(getuid),
+    SCMP_SYS(getuid32),
     SCMP_SYS(rt_sigaction),
     SCMP_SYS(rt_sigreturn),
     SCMP_SYS(rt_sigprocmask),
-- 
cgit v1.2.3


From d6956188c3599af2ebd089a98adb43b10b3d1eec Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Sun, 15 Aug 2021 15:08:56 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From da07bb5d81fcbec99f93ad66246dfa039bf5b18a Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 9 Aug 2021 11:48:21 +0200
Subject: sys_linux: allow clone3 and pread64 in seccomp filter

These seem to be needed with the latest glibc.


Gbp-Pq: Name allow-clone3-and-pread64-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys_linux.c b/sys_linux.c
index 50c0843..2b53f72 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -503,6 +503,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
 
     /* Process */
     SCMP_SYS(clone),
+#ifdef __NR_clone3
+    SCMP_SYS(clone3),
+#endif
     SCMP_SYS(exit),
     SCMP_SYS(exit_group),
     SCMP_SYS(getpid),
@@ -595,6 +598,7 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
 #ifdef __NR_ppoll_time64
     SCMP_SYS(ppoll_time64),
 #endif
+    SCMP_SYS(pread64),
     SCMP_SYS(pselect6),
 #ifdef __NR_pselect6_time64
     SCMP_SYS(pselect6_time64),
-- 
cgit v1.2.3


From 9c3d434e27335077bb2d6469e4a88f5519c271bc Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 7 Oct 2021 15:23:28 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 6153bcbab999999cc979c9a06b10215ca9a3a8c5 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 9 Aug 2021 11:48:21 +0200
Subject: sys_linux: allow clone3 and pread64 in seccomp filter

These seem to be needed with the latest glibc.


Gbp-Pq: Name allow-clone3-and-pread64-in-seccomp-filter.patch
---
 sys_linux.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys_linux.c b/sys_linux.c
index 50c0843..2b53f72 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -503,6 +503,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
 
     /* Process */
     SCMP_SYS(clone),
+#ifdef __NR_clone3
+    SCMP_SYS(clone3),
+#endif
     SCMP_SYS(exit),
     SCMP_SYS(exit_group),
     SCMP_SYS(getpid),
@@ -595,6 +598,7 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
 #ifdef __NR_ppoll_time64
     SCMP_SYS(ppoll_time64),
 #endif
+    SCMP_SYS(pread64),
     SCMP_SYS(pselect6),
 #ifdef __NR_pselect6_time64
     SCMP_SYS(pselect6_time64),
-- 
cgit v1.2.3


From f868d45269eb9b33b6a879fc6328a4f05c99d410 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Wed, 6 Oct 2021 10:02:34 +0200
Subject: sys_linux: fix seccomp filter for BINDTODEVICE option

The BINDTODEVICE socket option is the first option in the seccomp filter
setting a string instead of int. Remove the length check from the
setsockopt rules to allow a device name longer than 3 characters.

This was reported in Debian bug #995207.

Fixes: b9f5ce83b02e ("sys_linux: allow BINDTODEVICE option in seccomp filter")

Origin: upstream, https://git.tuxfamily.org/chrony/chrony.git/commit/?id=29d7d3176d9d1b208039a9d2ca3f26bc3cc5a387
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995207

Gbp-Pq: Name fix-seccomp-filter-for-BINDTODEVICE-socket-option.patch
---
 sys_linux.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/sys_linux.c b/sys_linux.c
index 2b53f72..5959d51 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -754,10 +754,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
 
     /* Allow selected socket options */
     for (i = 0; i < sizeof (socket_options) / sizeof (*socket_options); i++) {
-      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), 3,
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), 2,
                            SCMP_A1(SCMP_CMP_EQ, socket_options[i][0]),
-                           SCMP_A2(SCMP_CMP_EQ, socket_options[i][1]),
-                           SCMP_A4(SCMP_CMP_LE, sizeof (int))) < 0)
+                           SCMP_A2(SCMP_CMP_EQ, socket_options[i][1])))
         goto add_failed;
     }
 
-- 
cgit v1.2.3


From 06cf84631e605eab6d5f0653e8df556181f13382 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 12 Jan 2022 18:08:34 +0100
Subject: test: ensure awk commands in 008-ntpera return an integer

Some awk interpreters (e.g. mawk) print long integers in exponential
notation skewing the test result.

Bug: https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2022/01/msg00001.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=b61cbed6895fcd3eae4c8458a69995870a22a5e0
Last-Update: 2022-01-13

Gbp-Pq: Name ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
---
 test/simulation/008-ntpera | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/008-ntpera b/test/simulation/008-ntpera
index 2a4f332..2eea63b 100755
--- a/test/simulation/008-ntpera
+++ b/test/simulation/008-ntpera
@@ -29,7 +29,7 @@ echo "$ntp_start" | grep -q '-' && test_skip
 
 for time_offset in -1e-1 1e-1; do
 	for start_offset in 0 "2^32 - $limit"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
@@ -38,7 +38,7 @@ for time_offset in -1e-1 1e-1; do
 	done
 
 	for start_offset in -$limit "2^32"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
-- 
cgit v1.2.3


From e5fb35708f8452922b76228ed5f03cfeb71265de Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Thu, 13 Jan 2022 14:01:35 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 4287866224a3f33fe0e4fac2d317976c2c1d16b7 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 12 Jan 2022 18:08:34 +0100
Subject: test: ensure awk commands in 008-ntpera return an integer

Some awk interpreters (e.g. mawk) print long integers in exponential
notation skewing the test result.

Bug: https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2022/01/msg00001.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=b61cbed6895fcd3eae4c8458a69995870a22a5e0
Last-Update: 2022-01-13

Gbp-Pq: Name ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
---
 test/simulation/008-ntpera | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/008-ntpera b/test/simulation/008-ntpera
index 2a4f332..2eea63b 100755
--- a/test/simulation/008-ntpera
+++ b/test/simulation/008-ntpera
@@ -29,7 +29,7 @@ echo "$ntp_start" | grep -q '-' && test_skip
 
 for time_offset in -1e-1 1e-1; do
 	for start_offset in 0 "2^32 - $limit"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
@@ -38,7 +38,7 @@ for time_offset in -1e-1 1e-1; do
 	done
 
 	for start_offset in -$limit "2^32"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
-- 
cgit v1.2.3


From 3ba66353a114a87725e3d2a1b4729aaef7565749 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Tue, 1 Feb 2022 20:42:35 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From f23c7bed07403f807d9f620509fc8d141f9c1b59 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Sat, 20 Aug 2022 18:41:53 +0200
Subject: d/patches/: Add allow-rseq-in-seccomp-filter.patch

Closes: #1017790
---
 debian/patches/allow-rseq-in-seccomp-filter.patch | 33 +++++++++++++++++++++++
 debian/patches/series                             |  1 +
 2 files changed, 34 insertions(+)
 create mode 100644 debian/patches/allow-rseq-in-seccomp-filter.patch

diff --git a/debian/patches/allow-rseq-in-seccomp-filter.patch b/debian/patches/allow-rseq-in-seccomp-filter.patch
new file mode 100644
index 0000000..4e241ca
--- /dev/null
+++ b/debian/patches/allow-rseq-in-seccomp-filter.patch
@@ -0,0 +1,33 @@
+From 8bb8f15a7d049ed26c69d95087065b381f76ec4d Mon Sep 17 00:00:00 2001
+From: Michael Hudson-Doyle <michael.hudson@canonical.com>
+Date: Wed, 9 Feb 2022 09:06:13 +0100
+Subject: sys_linux: allow rseq in seccomp filter
+
+Libc 2.35 will use rseq syscalls [1][2] by default and thereby
+break chrony in seccomp isolation.
+
+[1]: https://www.efficios.com/blog/2019/02/08/linux-restartable-sequences/
+[2]: https://sourceware.org/pipermail/libc-alpha/2022-February/136040.html
+
+Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
+Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
+Signed-off-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
+Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
+
+diff --git a/sys_linux.c b/sys_linux.c
+index 9cab2ef..cc3c931 100644
+--- a/sys_linux.c
++++ b/sys_linux.c
+@@ -497,6 +497,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
+     SCMP_SYS(getrlimit),
+     SCMP_SYS(getuid),
+     SCMP_SYS(getuid32),
++#ifdef __NR_rseq
++    SCMP_SYS(rseq),
++#endif
+     SCMP_SYS(rt_sigaction),
+     SCMP_SYS(rt_sigreturn),
+     SCMP_SYS(rt_sigprocmask),
+-- 
+cgit v0.10.2
+
diff --git a/debian/patches/series b/debian/patches/series
index 92c6424..ad08b09 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1,2 +1,3 @@
+allow-rseq-in-seccomp-filter.patch
 ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
 nm-dispatcher-dhcp_Move-server_dir-to-run.patch
-- 
cgit v1.2.3


From 580cd8de75d9a79fd6d8ea642a821133aa3863e6 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Sat, 20 Aug 2022 18:50:11 +0200
Subject: d/changelog: Update for the 4.2-3 release

---
 debian/changelog | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 2ea7ed3..9764994 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,10 @@
+chrony (4.2-3) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-rseq-in-seccomp-filter.patch. (Closes: #1017790)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 20 Aug 2022 18:43:50 +0200
+
 chrony (4.2-2) unstable; urgency=medium
 
   * debian/usr.sbin.chronyd:
-- 
cgit v1.2.3


From 5ce9493d7a9ec49192acbdb0be6eec0edc9cf20f Mon Sep 17 00:00:00 2001
From: Michael Hudson-Doyle <michael.hudson@canonical.com>
Date: Wed, 9 Feb 2022 09:06:13 +0100
Subject: sys_linux: allow rseq in seccomp filter

Libc 2.35 will use rseq syscalls [1][2] by default and thereby
break chrony in seccomp isolation.

[1]: https://www.efficios.com/blog/2019/02/08/linux-restartable-sequences/
[2]: https://sourceware.org/pipermail/libc-alpha/2022-February/136040.html

Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Signed-off-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>


Gbp-Pq: Name allow-rseq-in-seccomp-filter.patch
---
 sys_linux.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys_linux.c b/sys_linux.c
index 9cab2ef..cc3c931 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -497,6 +497,9 @@ SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
     SCMP_SYS(getrlimit),
     SCMP_SYS(getuid),
     SCMP_SYS(getuid32),
+#ifdef __NR_rseq
+    SCMP_SYS(rseq),
+#endif
     SCMP_SYS(rt_sigaction),
     SCMP_SYS(rt_sigreturn),
     SCMP_SYS(rt_sigprocmask),
-- 
cgit v1.2.3


From 6efaea44d8d60ce7ecd68a00c686d3c1b0dea14d Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 12 Jan 2022 18:08:34 +0100
Subject: test: ensure awk commands in 008-ntpera return an integer

Some awk interpreters (e.g. mawk) print long integers in exponential
notation skewing the test result.

Bug: https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2022/01/msg00001.html
Applied-Upstream: https://git.tuxfamily.org/chrony/chrony.git/commit/?id=b61cbed6895fcd3eae4c8458a69995870a22a5e0
Last-Update: 2022-01-13

Gbp-Pq: Name ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
---
 test/simulation/008-ntpera | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/simulation/008-ntpera b/test/simulation/008-ntpera
index 2a4f332..2eea63b 100755
--- a/test/simulation/008-ntpera
+++ b/test/simulation/008-ntpera
@@ -29,7 +29,7 @@ echo "$ntp_start" | grep -q '-' && test_skip
 
 for time_offset in -1e-1 1e-1; do
 	for start_offset in 0 "2^32 - $limit"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
@@ -38,7 +38,7 @@ for time_offset in -1e-1 1e-1; do
 	done
 
 	for start_offset in -$limit "2^32"; do
-		export CLKNETSIM_START_DATE=$(awk "BEGIN {print $ntp_start + $start_offset}")
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
 		run_test || test_fail
 		check_chronyd_exit || test_fail
 		check_source_selection || test_fail
-- 
cgit v1.2.3


From adc8a9c943a885a1197bc15bcbcfd08beabddcd8 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Sat, 20 Aug 2022 18:43:50 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 6ea4c37..1b082af 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -11,7 +11,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 default_server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 # DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
-- 
cgit v1.2.3


From 657b106436ff984ea72dda340982c6a4247ed835 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 31 Aug 2022 13:32:14 +0200
Subject: Import chrony_4.3-1.debian.tar.xz

[dgit import tarball chrony 4.3-1 chrony_4.3-1.debian.tar.xz]
---
 .gitlab-ci.yml                                     |   11 +
 NEWS                                               |   70 +
 README.Debian                                      |   29 +
 changelog                                          | 2568 ++++++++++++++++++++
 chrony-dnssrv@.service                             |   17 +
 chrony-dnssrv@.timer                               |    9 +
 chrony-helper                                      |  264 ++
 chrony.conf                                        |   47 +
 chrony.default                                     |    6 +
 chrony.dhcp                                        |   27 +
 chrony.examples                                    |    1 +
 chrony.if-post-down                                |   11 +
 chrony.if-up                                       |   11 +
 chrony.keys                                        |   10 +
 chrony.lintian-overrides                           |    7 +
 chrony.maintscript                                 |    1 +
 chrony.ppp.ip-down                                 |   13 +
 chrony.ppp.ip-up                                   |   12 +
 chrony.service                                     |   65 +
 clean                                              |    1 +
 conf.d/README                                      |    7 +
 control                                            |   54 +
 copyright                                          |  187 ++
 dirs                                               |    6 +
 docs                                               |    3 +
 init                                               |   69 +
 install                                            |    7 +
 links                                              |    5 +
 ntp-units.d/50-chrony.list                         |    1 +
 ...nm-dispatcher-dhcp_Move-server_dir-to-run.patch |   19 +
 patches/series                                     |    1 +
 postinst                                           |   73 +
 postrm                                             |   56 +
 prerm                                              |   28 +
 rules                                              |   45 +
 source/format                                      |    1 +
 sources.d/README                                   |   12 +
 tests/control                                      |   28 +
 tests/dynamically-add-source                       |   27 +
 tests/fragmented-configuration                     |   17 +
 tests/helper-functions                             |   53 +
 tests/ntp-server-and-nts-auth                      |   59 +
 tests/time-sources-from-dhcp-servers               |   44 +
 tests/upstream-simulation-test-suite               |   41 +
 tests/upstream-system-tests                        |   24 +
 upstream/metadata                                  |    8 +
 upstream/signing-key.asc                           |   52 +
 usr.sbin.chronyd                                   |   85 +
 watch                                              |    3 +
 49 files changed, 4195 insertions(+)
 create mode 100644 .gitlab-ci.yml
 create mode 100644 NEWS
 create mode 100644 README.Debian
 create mode 100644 changelog
 create mode 100644 chrony-dnssrv@.service
 create mode 100644 chrony-dnssrv@.timer
 create mode 100755 chrony-helper
 create mode 100644 chrony.conf
 create mode 100644 chrony.default
 create mode 100644 chrony.dhcp
 create mode 100644 chrony.examples
 create mode 100644 chrony.if-post-down
 create mode 100644 chrony.if-up
 create mode 100644 chrony.keys
 create mode 100644 chrony.lintian-overrides
 create mode 100644 chrony.maintscript
 create mode 100644 chrony.ppp.ip-down
 create mode 100644 chrony.ppp.ip-up
 create mode 100644 chrony.service
 create mode 100644 clean
 create mode 100644 conf.d/README
 create mode 100644 control
 create mode 100644 copyright
 create mode 100644 dirs
 create mode 100644 docs
 create mode 100644 init
 create mode 100644 install
 create mode 100644 links
 create mode 100644 ntp-units.d/50-chrony.list
 create mode 100644 patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
 create mode 100644 patches/series
 create mode 100644 postinst
 create mode 100644 postrm
 create mode 100644 prerm
 create mode 100755 rules
 create mode 100644 source/format
 create mode 100644 sources.d/README
 create mode 100644 tests/control
 create mode 100644 tests/dynamically-add-source
 create mode 100644 tests/fragmented-configuration
 create mode 100644 tests/helper-functions
 create mode 100644 tests/ntp-server-and-nts-auth
 create mode 100644 tests/time-sources-from-dhcp-servers
 create mode 100644 tests/upstream-simulation-test-suite
 create mode 100755 tests/upstream-system-tests
 create mode 100644 upstream/metadata
 create mode 100644 upstream/signing-key.asc
 create mode 100644 usr.sbin.chronyd
 create mode 100644 watch

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000..5e3f0db
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,11 @@
+include:
+    - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/salsa-ci.yml
+    - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/pipeline-jobs.yml
+
+# Skip the reprotest job as long as it is run as root due to problems with
+# chrony system tests.
+reprotest:
+    extends: .test-reprotest
+    only:
+        variables:
+            - $SEE_YOU_SOON_REPROTEST
diff --git a/NEWS b/NEWS
new file mode 100644
index 0000000..fe7e4b9
--- /dev/null
+++ b/NEWS
@@ -0,0 +1,70 @@
+chrony (4.1~pre1-1) experimental; urgency=medium
+
+  Starting with chrony 4.0, it is possible to specify NTP sources in files
+  having the .sources suffix. In Debian, these files can be placed in
+  /etc/chrony/sources.d/ or any other directories specified by the 'sourcedir'
+  directive.
+  I would like to draw your attention that with chrony 4.1, each line of a
+  source file *must* be terminated by a trailing newline. Failing that, the NTP
+  source(s) will be ignored.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 25 Apr 2021 12:44:09 +0200
+
+chrony (3.4-2) unstable; urgency=medium
+
+  To reduce the range of operations available to chronyd, and thereby decrease
+  the kernel attack surface, a system call filter is now active by default
+  wherever¹ possible.
+  Please, take into account that this change prevents the use of the
+  “mailonchange” directive in chrony.conf as the chronyd process will not be
+  allowed to fork and execute the sendmail binary. Therefore, it is fundamental
+  to disable the system call filter to continue using this directive!
+
+  To do so, edit the /etc/default/chrony file and substitute the “-F -1”
+  parameter with “-F 0”. Restart chrony afterward.
+
+  ¹Are currently excluded alpha, ia64, m68k, riscv64, sh4 and sparc64
+   architectures due to lack of support in “libseccomp” and/or the Linux kernel.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 10 Feb 2019 18:44:22 +0100
+
+chrony (2.2.1-1) unstable; urgency=medium
+
+  In chrony versions before 2.2, the 'chrony.keys' file contained a command
+  key used for run-time configuration via the 'chronyc' command-line tool.
+  Starting from this version, support for this authentication method has been
+  dropped in favor of a Unix domain socket accessible only *locally* by root or
+  the _chrony system user. Consequently, if you refuse to use the 'chrony.keys'
+  file template provided by the maintainers when upgrading, please don’t forget
+  to manually remove the obsolete command key (ID 1) in the aforementioned file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 07 Feb 2016 17:02:30 +0100
+
+chrony (2.1.1-1) unstable; urgency=medium
+
+  From this version, 'chronyd' will strictly act as an NTP client by default. If
+  you want it to serve time to other systems, please do so by configuring the
+  'allow' directive.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 12 Oct 2015 19:12:39 +0200
+
+chrony (1.31.1-1) unstable; urgency=medium
+
+  From now on, we use the "hwclockfile" directive in /etc/chrony/chrony.conf.
+  Basically, it makes the detection of the standard (Local or UTC time) set
+  in /etc/adjtime — and used by the hardware clock — clearer compared to the
+  text processing method we used to use in the post install script to complete
+  the same task. Note that it overrides the "rtconutc" directive.
+
+  Also, we now create the _chrony system user to which chronyd will drop root
+  privileges. For users already allowing chronyd to drop root privileges in
+  favor of the user configured by the "user" directive in
+  /etc/chrony/chrony.conf, your configuration will remain unchanged and will
+  still work as intended.
+  However, some users might use a custom init script to accomplish the same
+  task by invoking chronyd with the '-u' option. We advise you to drop this
+  option from your init script before upgrading, otherwise you’ll have to
+  readjust the owner of the /var/l{ib,og}/chrony directories (recursively) to
+  the user you configured in your init script.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 6 Sep 2015 22:14:54 +0200
diff --git a/README.Debian b/README.Debian
new file mode 100644
index 0000000..2188ed9
--- /dev/null
+++ b/README.Debian
@@ -0,0 +1,29 @@
+Chrony for Debian
+-----------------
+
+ Notes about Debian-specific changes:
+
+ - Default chrony’s configuration files are located in the /etc/chrony directory.
+   It is filled by two important files:
+        → chrony.conf (configuration of the chronyd daemon, see man 5 chrony.conf
+          for further information)
+
+        → chrony.keys (lists keys used for NTP packets authentication, see
+          the “keyfile” directive in the chrony.conf(5) man page)
+
+ - We also provide /etc/ppp/ip-up.d/chrony and /etc/ppp/ip-down.d/chrony
+   to put chronyd online/offline depending on the PPP link status.
+
+ - Since version 1.31.1-1, we create the _chrony system user to which chronyd
+   will drop root privileges on initialisation. For users already allowing
+   chronyd to drop root privileges in favor of the user configured by the "user"
+   directive in chrony.conf, your configuration will remain unchanged and will
+   still work as it did. However, if you don’t want to deviate from Debian’s
+   default configuration, delete or comment out the "user" directive in
+   chrony.conf and recursively change the owner of the /var/lib/chrony and
+   /var/log/chrony directories. For example:
+
+        # sed -i 's/^user/#user/' /etc/chrony/chrony.conf
+        # chown -R _chrony:_chrony /var/l{ib,og}/chrony
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 01 Mar 2019 19:02:12 +0100
diff --git a/changelog b/changelog
new file mode 100644
index 0000000..871f2dd
--- /dev/null
+++ b/changelog
@@ -0,0 +1,2568 @@
+chrony (4.3-1) unstable; urgency=medium
+
+  * Import upstream version 4.3:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  [ Bastian Blank ]
+  * debian/chrony.service:
+    - Let systemd handle directories. (MR: !9)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 31 Aug 2022 13:32:14 +0200
+
+chrony (4.3~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 4.3-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/chrony.lintian-overrides:
+    - Update lintian override syntax.
+
+  * debian/control:
+    - Bump Standards-Version to 4.6.1 (no changes needed).
+
+  * debian/patches/*:
+    - Drop ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch,
+    applied upstream.
+    - Refresh nm-dispatcher-dhcp_Move-server_dir-to-run.patch.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 11 Aug 2022 14:12:25 +0200
+
+chrony (4.2-2) unstable; urgency=medium
+
+  * debian/usr.sbin.chronyd:
+    - Allow reading the chronyd configuration file that timemaster(8)
+    generates. Thanks to Michael Lestinsky for the report! (Closes: #1004745)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 01 Feb 2022 20:42:35 +0100
+
+chrony (4.2-1) unstable; urgency=medium
+
+  * Import upstream version 4.2:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/chrony.service:
+    - Adopt upstream service unit hardening options.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/patches/*:
+    - Drop patches applied upstream.
+    - Add ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
+
+  * debian/test/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 13 Jan 2022 14:01:35 +0100
+
+chrony (4.1-4) unstable; urgency=medium
+
+  * debian/:
+    - Remove empty preinst maintainer script.
+
+  * debian/chrony.lintian-overrides:
+    - Remove unused overrides.
+
+  * debian/control:
+    - Bump Standards-Version to 4.6.0 (no changes needed).
+
+  * debian/patches/*:
+    - Add fix-seccomp-filter-for-BINDTODEVICE-socket-option.patch.
+    (Closes: #995207)
+
+  * debian/usr.sbin.chronyd:
+    - Add 'vim:syntax=apparmor' modline.
+    - Add feature ABI rule. Starting with AppArmor 3.0, policy needs to contain
+    an abi rule to indicate which feature abi the policy was developed under.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 07 Oct 2021 15:23:28 +0200
+
+chrony (4.1-3) unstable; urgency=medium
+
+  * Upload to unstable.
+
+  * debian/patches/:
+    - Add allow-clone3-and-pread64-in-seccomp-filter.patch.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 15 Aug 2021 15:08:56 +0200
+
+chrony (4.1-2) experimental; urgency=medium
+
+  * Merge branch 'debian/unstable' into 'debian/latest'.
+
+  * debian/rules:
+    - Remove needless dh_auto_test override.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/helper-functions:
+    - Improve chronyd restart logic. While rendering the tests more readable,
+    this also fixes ntp-server-and-nts-auth test on Ubuntu.
+
+  [ Debian Janitor ]
+  * debian/{control,chrony.maintscript}:
+    - Remove constraints unnecessary since stretch.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 26 Jun 2021 17:16:45 +0200
+
+chrony (4.1-1) experimental; urgency=medium
+
+  * Import upstream version 4.1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/upstream/signing-key.asc:
+    - Update Miroslav Lichvar's key.
+
+  * debian/watch:
+    - Add upstream version mangle to transform -pre to ~pre.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 14 May 2021 00:25:34 +0200
+
+chrony (4.1~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 4.1-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/control:
+    - Now that the upstream system tests support 'ss', replace the net-tools
+    build-dependency by iproute2.
+
+  * debian/NEWS:
+    - Mention that lines in *.sources files must be terminated by a trailing
+    newline.
+
+  * debian/patches/:
+    - Drop allow-IP_TOS-socket-option-in-seccomp-filter.patch. Applied
+    upstream.
+
+  * debian/postinst:
+    - Do not redirect 'chronyd -p' stderr to /dev/null. Not needed anymore.
+
+  * debian/sources.d/README:
+    - Mention that lines in *.sources files must be terminated by a trailing
+    newline.
+
+  * debian/tests/dynamically-add-source:
+    - Terminate the line in dummy-server.sources with the newline control
+    character.
+
+  * debian/tests/fragmented-configuration:
+    - Do not redirect 'chronyd -p' stderr to /dev/null. Not needed anymore.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 10 May 2021 18:56:53 +0200
+
+chrony (4.0-8) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-BINDTODEVICE-option-in-seccomp-filter.patch to enable support
+    for binding sockets to a device without having to disable the seccomp
+    filter.
+    - Add allow-getuid32-in-seccomp-filter.patch. Upstream found out that
+    getuid32() needed to be allowed in the seccomp filter to enable some NTS
+    operations on i686. This may affect other 32-bits architectures.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 13 May 2021 16:51:41 +0200
+
+chrony (4.0-7) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-IP_TOS-socket-option-in-seccomp-filter.patch to enable the use
+    of the 'dscp' directive.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 08 Apr 2021 16:21:16 +0200
+
+chrony (4.0-6) unstable; urgency=medium
+
+  * debian/tests/helper-functions:
+    - Instead of running 'systemctl restart chrony.service', use
+    __restart_chronyd() in the __no_system_clock_control() function.
+    - Run 'sleep 3' only if chronyd has successfully restarted.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/{dynamically-add-source,ntp-server-and-nts-auth}:
+    - Reduce default Ubuntu config to make space for testcase config.
+
+  * debian/tests/helper-functions:
+    - Add more common functions and update some tests to use them.
+    - Wait after restarting chronyd. Without this, some tests break on Ubuntu by
+    checking state too early.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 21 Feb 2021 21:59:22 +0100
+
+chrony (4.0-5) unstable; urgency=medium
+
+  * Follow DEP-14 branch naming conventions:
+    master -> debian/latest
+    upstream -> upstream/latest
+
+  * debian/chrony.service:
+    - Enable some hardening settings.
+
+  * debian/control:
+    - Remove Joachim Wiedorn from the Uploaders field. This decision was taken
+    in agreement with him. Thanks a lot, Joachim, for your work on chrony and
+    for your benevolence when you handed me its maintenance.
+    - Point Vcs-Git to the debian/latest branch.
+
+  * debian/dirs:
+    - Do not create the /etc/apparmor.d/force-complain directory. Not needed
+    anymore.
+
+  * debian/postrm:
+    - Remove /run/chrony-dhcp on purge.
+
+  * debian/preinst:
+    - Drop old migration code snippet. It was used to put the newly provided
+    AppArmor profile in complain mode when upgrading chrony to prevent
+    regressions this profile could have caused. (Closes: #905485)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 04 Feb 2021 19:49:22 +0100
+
+chrony (4.0-4) unstable; urgency=medium
+
+  * debian/chrony.examples:
+    - Provide example configuration files.
+
+  * debian/postinst:
+    - Run adduser unconditionally.
+    - Use 'chronyd -p' to check the whole configuration.
+
+  * debian/tests/:
+    - Prevent dynamically-add-source and ntp-server-and-nts-auth tests from
+    failing on chronyd's preparation step.
+    - Don't pass 'set -u' to dynamically-add-source and
+    ntp-server-and-nts-auth scripts.
+
+  * debian/tests/control:
+    - Mark dynamically-add-source as skippable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 21 Jan 2021 20:02:39 +0100
+
+chrony (4.0-3) unstable; urgency=medium
+
+  * debian/:
+    - chronyd's configuration can now be fragmented. Please see
+    /etc/chrony/conf.d/README for more information.
+    - NTP sources can be specified in /etc/chrony/sources.d. Please see
+    /etc/chrony/sources.d/README for more information.
+
+  * debian/chrony.conf:
+    - Include configuration files found in /etc/chrony/conf.d.
+    - Use NTP sources found in /etc/chrony/sources.d.
+    - Get TAI-UTC offset and leap seconds from the system tz database by using
+    the "leapsectz right/UTC" directive. This directive must be commented out
+    when using time sources serving leap-smeared time. (Closes: #974845)
+    - Add missing comment.
+
+  * debian/chrony.default:
+    - Switch the seccomp filter to level 1.
+
+  * debian/chrony.lintian-overrides:
+    - Override breakout-link.
+
+  * debian/control:
+    - Add tzdata to the dependencies.
+    - Bump Standards-Version to 4.5.1 (no changes required).
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/postinst:
+    - Use dpkg-statoverride to manage mode bits and ownership of
+    /var/l{ib,og}/chrony.
+
+  * debian/postrm:
+    - Remove overrides for /var/l{ib,og}/chrony on purge.
+
+  * debian/rules:
+    - Drop '--without-readline' option. GNU readline support has been dropped
+    upstream due to license incompatibility.
+    - Replace -F -1 by -F 1 in the sed invocation.
+
+  * debian/tests/:
+    - Add fragmented-configuration autopkgtest.
+    - Add dynamically-add-source autopkgtest.
+    - Add ntp-server-and-nts-auth autopkgtest.
+
+  * debian/tests/control:
+    - Mark ntp-server-and-nts-auth as skippable.
+
+  * debian/tests/fragmented-configuration:
+    - Use another directive for the test since "leapsectz right/UTC" is now
+    used by default.
+
+  * debian/tests/helper-functions:
+    - Add __no_system_clock_control() function.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Always use the same seed to get deterministic results.
+
+  * debian/upstream/metadata:
+    - Remove obsolete field Name. Thanks to Debian Janitor <janitor@jelmer.uk>.
+
+  * debian/usr.sbin.chronyd:
+    - Make use of the @{run} variable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 18 Jan 2021 21:58:52 +0100
+
+chrony (4.0-2) unstable; urgency=medium
+
+  * Merge branch 'experimental' into 'master'.
+
+  * Upload to unstable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 13 Oct 2020 15:59:33 +0200
+
+chrony (4.0-1) experimental; urgency=medium
+
+  * Import upstream version 4.0:
+    - This release adds support for the Network Time Security (NTS)
+    authentication mechanism (RFC 8915).
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 07 Oct 2020 19:14:51 +0200
+
+chrony (4.0~pre4-2) experimental; urgency=medium
+
+  * debian/postinst:
+    - Fix user and group ownership of "/var/lib/chrony" to allow chronyd
+    to write in it. This will also fix a regression in the 104-systemdirs
+    test.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 03 Oct 2020 11:20:02 +0200
+
+chrony (4.0~pre4-1) experimental; urgency=medium
+
+  * Import upstream version 4.0-pre4:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * Merge branch 'master' into experimental. (Closes: #970421)
+
+  * debian/chrony.conf:
+    - Use NTP sources from /run/chrony-dhcp.
+    - Save NTS keys and cookies in /var/lib/chrony/.
+
+  * debian/chrony-dnssrv@.service:
+    - Update "chrony-helper" path.
+
+  * debian/chrony.dhcp:
+    - Save NTP servers from DHCP to /run/chrony-dhcp/$interface.sources.
+
+  * debian/chrony.lintian-overrides:
+    - Override executable-in-usr-lib for NetworkManager dispatcher scripts.
+    - Update NetworkManager dispatcher script name.
+
+  * debian/chrony.ppp.ip-{down,up}:
+    - Update PID file path.
+
+  * debian/chrony.service:
+    - Update PID file path.
+    - Do not run 'chrony-helper update-daemon' after starting chronyd. Not
+    needed anymore.
+
+  * debian/control:
+    - Build-depend on libgnutls28-dev to support NTS.
+    - Build-depend on gnutls-bin for the test suite.
+    - Bump debhelper-compat to 13.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/dirs:
+    - Remove var/log/chrony as it will be created automatically if it doesn’t
+    exist.
+
+  * debian/if-{post-down,up}:
+    - Update PID file path.
+
+  * debian/init:
+    - Update PID file path.
+    - Drop the unnecessary '--remove pidfile' option from the stop target.
+    - Do not run 'chrony-helper update-daemon' after starting chronyd. Not
+    needed anymore.
+
+  * debian/install:
+    - Move "chrony-helper" to "/usr/libexec/chrony".
+
+  * debian/links:
+    - Update source and destination filenames.
+
+  * debian/patches/:
+    - Drop patches applied upstream.
+    - Add nm-dispatcher-dhcp_Move-server_dir-to-run.patch.
+
+  * debian/postinst:
+    - Drop migration code from pre-Stretch.
+    - Migrate NTP sources obtained from DHCP to /run/chrony-dhcp on upgrade
+    from chrony < 4.0~pre4-1.
+    - Remove staled PID file when upgrading from chrony < 4.0~pre4-1.
+
+  * debian/rules:
+    - Change the default PID file location from /run to /run/chrony.
+    - Drop dh_missing --fail-missing. This is the default in debhelper 13.
+    - Enable seccomp support by default on riscv64.
+    - Update NetworkManager dispatcher script name from 20-chrony to
+    20-chrony-onoffline.
+    - Add DHCP NetworkManager dispatcher script to allow chronyd to use
+    NTP sources obtained from NM's internal DHCP client.
+
+  * debian/tests/:
+    - Add some helper functions. Some tests will be updated thereafter
+    to use them.
+
+  * debian/tests/time-sources-from-dhcp-servers:
+    - Adapt to the new way of using time sources from DHCP.
+    - Improve sed invocation.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+    - Cosmetic changes.
+
+  * debian/tests/upstream-system-tests:
+    - No need to stop systemd-timesyncd anymore since it is no more
+    co-installable with chrony anymore.
+
+  * debian/usr.sbin.chronyd:
+    - Update PID file path.
+    - Add dac_override and dac_read_search capabilities to give "root" the
+    ability to write the PID file in /run/chrony/.
+    - Prefix flag definition by "flags=".
+    - Sort the capabilities.
+    - Grant CAP_NET_RAW capability to allow an NTP socket to be bound to a
+    device using the SO_BINDTODEVICE socket option on kernels before 5.7.
+    - Add comments regarding capabilities.
+    - Let chronyd create /var/l{ib,og}/chrony.
+    - Remove a superfluous rule.
+    - Allow reading of NTP sources in /run/chrony-dhcp/.
+
+  * debian/watch:
+    - Make use of special strings.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 02 Oct 2020 21:21:08 +0200
+
+chrony (3.5.1-1) unstable; urgency=medium
+
+  * Import upstream version 3.5.1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+    - CVE-2020-14367: create new file when writing pidfile.
+
+  * debian/chrony.lintian-overrides:
+    - Remove unused override.
+
+  [ Ville Skyttä ]
+  * debian/chrony.conf:
+    - Comment spelling fix. (MR: !5)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 20 Aug 2020 14:07:22 +0200
+
+chrony (3.5-9) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-some-*time64-syscalls-in-seccomp-filter.patch. Needed for
+    32-bit architectures with new system calls using 64-bit time_t.
+    (LP: #1878005)
+
+  * debian/tests/control:
+    - Add needs-internet restriction to the upstream-simulation-test-suite
+    test.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-simulation-test-suite:
+    - Skip if preparation steps fail.
+    - Make preparation steps more verbose.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 19 May 2020 16:42:18 +0200
+
+chrony (3.5-8) unstable; urgency=medium
+
+  * debian/postrm:
+    - Stop starting systemd-timesyncd in postrm. This is no longer relevant
+    since systemd-timesyncd is a standalone package declaring
+    Conflicts/Replaces/Provides: time-daemon. (Closes: #955773)
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-system-tests:
+    - Stop chrony/systemd-timesynd before running these tests. (LP: #1870144)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 05 Apr 2020 17:44:31 +0200
+
+chrony (3.5-7) unstable; urgency=medium
+
+  * debian/chrony.maintscript:
+    - Remove the /etc/NetworkManager/dispatcher.d/20-chrony conffile.
+
+  * debian/control:
+    - Support seccomp facility on riscv64. It should be noted that the system
+    call filter will stay disabled by default on this architecture until
+    Linux >= 5.5 hits unstable.
+    - Bump libseccomp-dev build-dep to 2.4.3-1~ to provide seccomp facility on
+    riscv64.
+    - Break network-manager (<< 1.20.0-1~). Prior to this version,
+    NetworkManager would not look for dispatcher scripts into
+    /usr/lib/NetworkManager/dispatcher.d/.
+
+  * debian/dirs:
+    - Create the usr/lib/NetworkManager/dispatcher.d subdirectories.
+
+  * debian/links:
+    - Change the location of the NetworkManager dispatcher script.
+
+  * debian/patches/:
+    - Add allow-renameat2-in-seccomp-filter.patch. Required as the riscv64
+    architecture does not support the rename() and renameat() system calls.
+
+  * debian/rules:
+    - Move the NetworkManager dispatcher script in
+     /usr/lib/NetworkManager/dispatcher.d/.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 17 Mar 2020 15:21:53 +0100
+
+chrony (3.5-6) unstable; urgency=medium
+
+  * debian/chrony.service:
+    - Don’t conflict with systemd-timesyncd.service.
+    A few users complain that chronyd does not start at boot. The way the
+    Conflict= directive works internally might cause both systemd-timesyncd
+    and chronyd to be inactive at boot. So by relying solely on the
+    disable-with-time-daemon.conf drop-in file provided by systemd, we should
+    get rid of this malfunction while still preventing these two time daemons
+    from being active at the same time. Kudos notably go to Santiago Vila for
+    the report and providing SSH access to a GCE instance where the issue was
+    reproducible and Michael Biebl for debugging. (Closes: #947936)
+
+  * debian/control:
+    - Bump Standards-Version to 4.5.0 (no changes required).
+    - No need to explicitly conflict with ntp as it now provides time-daemon.
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/patches/:
+    - Add allow-clock_adjtime-in-seccomp-filter.patch.
+    glibc 2.31 switched the adjtimex() function to the clock_adjtime
+    system call.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version. This new version supports glibc >= 2.31 headers.
+    (LP: #1866753)
+
+  * debian/tests/control:
+    - Run the upstream-simulation-test-suite as root.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 10 Mar 2020 19:17:16 +0100
+
+chrony (3.5-5) unstable; urgency=medium
+
+  * debian/control:
+    - Bump standard-version to 4.4.1 (no change required).
+
+  * debian/install:
+    - Install 50-chrony.list in /usr/lib/systemd/ntp-units.d.
+
+  * debian/ntp-units.d/50-chrony.list:
+    - Allow timedated to interact with chronyd.
+
+  * debian/patches/*:
+    - Cherry-pick upstream commits to better manage RTCs that don't support
+    interrupts. This fixes an issue exhibited when a specific upstream system
+    test is run on the Ubuntu CI. Thank to Christian Ehrhardt for working
+    with Miroslav Lichvar to address this problem.
+
+  * debian/tests/control:
+    - Use @builddeps@ as a test dependency for upstream_system_tests.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-simulation-test-suite:
+    - Redirect stderr on make call to stdout. On some architectures (e.g. armhf)
+    the clksim tests compile but throw some warnings. (MR: !2)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 22 Dec 2019 17:30:40 +0100
+
+chrony (3.5-4) unstable; urgency=medium
+
+  * debian/tests/control:
+    - Add @builddeps@ to the list of dependencies needed by the
+    upstream-simulation-test-suite test.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 30 Aug 2019 00:49:20 +0200
+
+chrony (3.5-3) unstable; urgency=medium
+
+  * debian/chrony.lintian-overrides:
+    - Override package-supports-alternative-init-but-no-init.d-script. This
+    is a false positive. chrony-dnssrv@.service isn’t a daemon but a oneshot
+    service, not started at boot, whose role is to lookup for _ntp._udp DNS SRV
+    records.
+
+  * debian/chrony.service:
+    - Pull in time-sync.target and order chrony before it as recommended in
+    systemd.special(7).
+
+  * debian/control:
+    - Bump standard-version to 4.4.0 (no changes required).
+
+  * debian/.gitlab-ci.yml:
+    - Switch to standard Salsa Pipeline.
+    - Skip the reprotest job for as long as it is run as root due to problems
+    with chrony system tests.
+
+  * debian/tests/*:
+    - Revamp the upstream-simulation-test-suite test.
+    - Adjust dpkg dependencies for upstream-simulation-test-suite.
+    - Adjust restrictions for upstream-simulation-test-suite.
+    - Introduce upstream-system-tests. Add a new set of tests for testing
+    basic chronyd functionality. Destructive tests are run in a virtual
+    machine.
+    - Add ethtool to the list of dependencies needed by
+    run_destructive_system_tests.
+    - exit 77 if upstream-simulation-test-suite is run on non-Linux and mark
+    the test as skippable. Thanks to Paul Gevers <elbrus@debian.org> for the
+    suggestion.
+    - Make artifacts() exit 1. Again, thanks to Paul Gevers.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 13 Aug 2019 17:57:47 +0200
+
+chrony (3.5-2) unstable; urgency=medium
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/chrony.dhcp:
+    - Fix shellcheck warnings. Patch imported from Fedora.
+
+  * debian/chrony-helper:
+    - Fix shellcheck warnings. Patch imported from Fedora.
+
+  * debian/clean:
+    - Drop obsolete entries.
+
+  * debian/copyright:
+    - Update copyright years.
+    - Update copyright holder for the configure script.
+
+  * debian/patches/*:
+    - Add update_processing_of_packet_log.patch. This fixes a regression in
+    the simulation tests exhibited by the recent clknetsim changes.
+    (Closes: #931181)
+
+  * debian/rules:
+    - Use dh_missing --fail-missing.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Use a known good clknetsim commit. This should prevent regressions from
+    on-going “clknetsim” development.
+
+  * debian/usr.sbin.chronyd:
+    - Grant access rights only to the ntp_signd socket. (Closes: #928170)
+
+  [ Christian Ehrhardt ]
+  * debian/postrm:
+    - Re-establish systemd-timesyncd on removal. (MR: !1)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 06 Jul 2019 20:33:41 +0200
+
+chrony (3.5-1) experimental; urgency=medium
+
+  * Import upstream version 3.5:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/control:
+    - Ignore net-tools and procps build-dependencies if the profile nocheck is
+    active.
+
+  * debian/rules:
+    - No test suite should be run if nocheck is passed to DEB_BUILD_OPTIONS.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 15 May 2019 18:44:12 +0200
+
+chrony (3.5~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.5-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/.gitlab-ci.yml:
+    - Use .build-package template job instead of .build-unstable. The latter
+    is deprecated.
+
+  * debian/chrony.keys:
+    - Fix the comment about the location of the list of supported hash
+    functions and output encoding. These information are now available by
+    consulting the “keyfile” directive in the chrony.conf(5) man page.
+
+  * debian/control:
+    - Drop dependency on lsb-base. Is is required when booting with sysvinit
+    and initscripts, however initscripts already Depends on lsb-base.
+    - Build-depend on net-tools and procps. kill, netstat and ps are needed
+    for the new system tests executed at build time (iff building as root).
+
+  * debian/copyright:
+    - Add an entry for test/system/* files.
+
+  * debian/patches/*:
+    - Drop all patches, they have been applied upstream.
+
+  * debian/postinst:
+    - Drop migration code from pre-stretch.
+
+  * debian/README.Debian:
+    - Fix information related to the chrony.keys file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 12 May 2019 22:16:14 +0200
+
+chrony (3.4-4) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Add allow-further-syscalls-in-seccomp-filter.patch. Supplementing the
+    seccomp filter whitelist with those syscalls is a prerequisite, notably for
+    the arm64 architecture.
+
+  [ Leigh Brown ]
+  * debian/patches/*:
+    - Add allow-recv-send-in-seccomp-filter.patch. Necessary on armel and
+    ppc64el. Other architectures might also be affected. (Closes: #924494)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 18 Mar 2019 19:35:34 +0100
+
+chrony (3.4-3) unstable; urgency=medium
+
+  * debian/.gitlab-ci.yml:
+    - Check for missing hardening flags.
+
+  * debian/patches/*:
+    - Add allow-_llseek-in-seccomp-filter.patch. Needed on various 32-bit
+    plateforms to log the {raw}measurements and statistics information when
+    the seccomp filter is enabled. Thanks a lot to Francesco Poli (wintermute)
+    <invernomuto@paranoici.org> for the report. (Closes: #923137)
+    - Add allow-waitpid-in-seccomp-filter.patch. Needed to correctly stop
+    chronyd on some plateforms when the seccomp filter is enabled.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 04 Mar 2019 23:32:12 +0100
+
+chrony (3.4-2) unstable; urgency=medium
+
+  * debian/.gitlab-ci.yml:
+    - Replace home-made GitLab CI with the standard Salsa pipeline.
+    - Allow autopkgtest job to fail. The time-sources-from-dhcp-servers test
+    currently fails due to a testbed issue on salsa CI.
+
+  * debian/chrony.default:
+    - Enable the system call filter by default.
+
+  * debian/control:
+    - Bump standard-version to 4.3.0 (no changes required).
+    - Use the new debhelper-compat (= 12) notation and drop d/compat.
+    - Add Pre-Depends: ${misc:Pre-Depends}. Debhelper compatibility level 12
+    makes use of the “--skip-systemd-native” flag from “invoke-rc.d”. Adding
+    Pre-Depends: ${misc:Pre-Depends} to d/control ensure that we have a recent
+    enough version of “init-system-helpers”.
+    - Suggest networkd-dispatcher.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2019.
+
+  * debian/links:
+    - Now that “networkd-dispatcher” is in the Debian archive, link
+    NetworkManager dispatcher script to networkd-dispatcher routable and off
+    states. Patch cherry-picked from Ubuntu; thanks to Christian Ehrhardt
+    <christian.ehrhardt@canonical.com> for working on this.
+
+  * debian/NEWS:
+    - Report that a system call filter is now enabled by default and the way
+    to disable it if needed.
+
+  * debian/rules:
+    - Don’t enable the system call filter on some architectures due to missing
+    support in the “libseccomp” and/or the Linux kernel.
+
+  * debian/upstream/:
+    - Strip upstream key from extra signatures. Thanks lintian!
+    - Remove the Miroslav-Lichvar.txt file as it serves no purpose.
+
+  * debian/usr.sbin.chronyd:
+    - Don’t include “tunables/sys”. The etc/apparmor.d/tunables/sys file has
+    been deprecated in AppArmor 2.13.1! The @{sys} variable is now defined in
+    “tunables/kernelvars” which is included in “tunables/global”.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 13 Feb 2019 17:08:17 +0100
+
+chrony (3.4-1) unstable; urgency=medium
+
+  * Import upstream version 3.4:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/chrony.service:
+    - Conflict with ntpsec.service.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/patches/*:
+    - Remove fix-samplefilt-unit-test-to-work-with-low-precision-clock.patch,
+    fixed upstream.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 21 Sep 2018 14:12:03 +0200
+
+chrony (3.4~pre1-2) experimental; urgency=medium
+
+  * debian/patches/*:
+    - Cherry-pick upstream patch to fix samplefilt unit test to work with
+    low-precision clocks. This should prevent chrony from failing to build
+    from source on HPPA and Alpha.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 10 Sep 2018 18:39:58 +0200
+
+chrony (3.4~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.4-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/:
+    - Add “.gitlab-ci.yml” file to use GitLab Continuous Integration.
+
+  * debian/chrony.if-{post-down,up}:
+    - Use the new “onoffline” command to tell chronyd to switch all sources to
+    the online or offline status according to the current network configuration.
+
+  * debian/chrony.ppp.ip-{down,up}:
+    - As for ifupdown scripts, use the “onoffline” command.
+
+  * debian/control:
+    - Bump standard-version to 4.2.1 (no changes required).
+
+  * debian/patches/*:
+    - Remove fall-back-to-urandom.patch. Applied in this prerelease.
+
+  * debian/post{inst,rm}:
+    - Use “command -v” instead of “which” to enhance portability.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 02 Sep 2018 19:14:08 +0200
+
+chrony (3.3-3) unstable; urgency=medium
+
+  * debian/:
+    - Normalize packaging with “wrap-and-sort -ab”.
+
+  * debian/control:
+    - Bump standard-version to 4.2.0:
+        ↳ Install upstream release notes as “/usr/share/doc/chrony/NEWS.gz”.
+          Installing these as “/usr/share/doc/package/changelog.gz” is now
+          deprecated.
+
+  * debian/patches/:
+    - Cherry-pick upstream patch to avoid hangs when starting
+    chronyd on newer kernels by falling back to urandom.
+    Thanks to Gustavo Scalet <gustavo.scalet@collabora.com> for the report and
+    the initial patch. (LP: #1787366, Closes: #906276)
+
+  * debian/upstream/metadata:
+    - Add DEP12 upstream metadata file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 18 Aug 2018 16:23:19 +0200
+
+chrony (3.3-2) unstable; urgency=medium
+
+  * debian/chrony.service:
+    - Conflict with ntp.service.
+
+  * debian/control:
+    - Bump standard-version to 4.1.4 (no changes required).
+    - Switch to the Nettle cryptographic library for hash functions.
+
+  [ Helmut Grohne ]
+  * debian/rules:
+    - Pass CC to make and set “--host-system” to fix FTCBFS. (Closes: #895852)
+
+  [ Christian Ehrhardt ]
+  * debian/usr.sbin.chronyd:
+    - Support all paths suggested in the man page.
+    (LP: #1771028, Closes: #898614)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 14 May 2018 21:37:30 +0200
+
+chrony (3.3-1) unstable; urgency=medium
+
+  * Import upstream version 3.3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/copyright:
+    - Update copyright year.
+
+  * debian/usr.sbin.chronyd:
+    - Allow CAP_NET_ADMIN to support HW timestamping. (LP: #1761327)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 05 Apr 2018 02:08:31 +0200
+
+chrony (3.3~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.3-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/copyright:
+    - Add “hash_nettle.c” copyright information and update copyright year of
+    test/unit/*
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 15 Mar 2018 13:58:21 +0100
+
+chrony (3.2-5) unstable; urgency=medium
+
+  [ Christian Ehrhardt ]
+  * debian/usr.sbin.chronyd:
+    - Allow write access to RTC, PPS and PTP devices.
+    (Closes: #891201, LP: #1751241)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 28 Feb 2018 17:31:08 +0100
+
+chrony (3.2-4) unstable; urgency=medium
+
+  * debian/changelog:
+    - Remove trailing spaces.
+
+  * debian/chrony-dnssrv@.service:
+    - Use NTP servers obtained from DNS SRV records.
+
+  * debian/chrony-dnssrv@.timer:
+    - Periodic lookup of DNS SRV records.
+
+  * debian/chrony-helper:
+    - New helper script to make use of NTP servers obtained from DHCP and
+    _ntp._udp DNS SRV records.
+
+  * debian/chrony.dhcp:
+    - Add a dhclient-exit-hook script to add/remove NTP servers depending
+    on the operations invoked by the DHCP client. (Closes: #889656)
+
+  * debian/chrony.service:
+    - Run “/usr/lib/chrony/chrony-helper update-daemon” after starting chronyd.
+
+  * debian/control:
+    - Suggest dnsutils. The dig utility is used to update files with NTP
+    servers from DNS SRV records.
+
+  * debian/init:
+    - Run “/usr/lib/chrony/chrony-helper update-daemon” after starting chronyd.
+
+  * debian/install:
+    - Install the chrony-helper script in /usr/lib/chrony.
+    - Install chrony-dnssrv@.* files in /lib/systemd/system.
+
+  * debian/postinst:
+    - Don’t use recursive chown as this is vulnerable to hardlink attacks on
+    mainline, non-Debian kernels that do not have fs.protected_hardlinks=1.
+    Thanks Lintian!
+
+  * debian/postrm:
+    - Remove “/run/chrony” on purge.
+
+  * debian/rules:
+    - Install the dhclient-exit-hook script in /etc/dhcp/dhclient-enter-hooks.
+
+  * debian/tests/:
+    - Use autopkgtest to ensure that chronyd can use NTP servers obtained from
+    DHCP servers.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 20 Feb 2018 18:27:10 +0100
+
+chrony (3.2-3) unstable; urgency=medium
+
+  [ Christian Ehrhardt ]
+  * debian/chrony.default:
+    - Mention systemd service file in the comment.
+
+  * debian/chrony.service:
+    - Support the DAEMON_OPTS variable from “/etc/default/chrony” in systemd
+    environment. (LP: #1746081, Closes: #889012)
+
+  * debian/usr.sbin.chronyd:
+    - Allow the creation of /run/chrony on demand.
+    (LP: #1746444, Closes: #889011)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 07 Feb 2018 21:27:09 +0100
+
+chrony (3.2-2) unstable; urgency=medium
+
+  * Initial AppArmor profile for chronyd. Thanks to Jamie
+    Strandboge <jamie@ubuntu.com>. (Closes: #888038)
+
+  * debian/compat:
+    - Bump to debhelper compat 11.
+
+  * debian/control:
+    - Bump standard-version to 4.1.3 (no changes required).
+    - Build depend on debhelper ≥ 11.
+    - Set “Rules-Requires-Root: no”.
+    - Move Vcs-* to salsa.debian.org.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2018.
+
+  * debian/postinst:
+    - Don’t force removal of cron file since it doesn’t exist anymore.
+
+  * debian/preinst:
+    - Update the chrony version on which to act.
+    - Add the debhelper token.
+
+  * debian/usr.sbin.chronyd:
+    - Improve AppArmor profile to support more chronyd features and ease
+    portability with other distros.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 28 Jan 2018 19:33:46 +0100
+
+chrony (3.2-1) unstable; urgency=medium
+
+  * Import upstream version 3.2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 15 Sep 2017 11:37:10 +0200
+
+chrony (3.2~pre2-1) experimental; urgency=medium
+
+  * Import upstream version 3.2-pre2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/control:
+    - Bump standard-version to 4.1.0 (no changes required).
+
+  * debian/copyright:
+    - Update copyright years.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 30 Aug 2017 15:48:37 +0200
+
+chrony (3.2~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.2-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/patches/*:
+    - Remove allow_getpid_in_seccomp_filter.patch and update the series file
+    accordingly.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Run tests in multiple iterations.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 25 Jul 2017 21:13:22 +0200
+
+chrony (3.1-5) unstable; urgency=medium
+
+  * debian/chrony.if-up:
+    - Do not pass the “burst” command to chronyc as the script could return an
+    error in certain situations. As a consequence, that would prevent ifupdown
+    from writing the current state of the interfaces in /run/network/ifstate.
+    Thanks to John Eikenberry <jae@zhar.net> for reporting that issue.
+    (Closes: #868491)
+
+  * debian/chrony.ppp.ip-up:
+    - Take the same action as for the “chrony.if-up” script as a precautionary
+    measure.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 17 Jul 2017 16:47:56 +0200
+
+chrony (3.1-4) unstable; urgency=medium
+
+  * Now that Stretch has been released (\o/), let’s upload chrony 3.1 to
+    unstable.
+
+  * debian/:
+    - Remove the menu file used to launch “chronyc”. It is a CLI only tool,
+    thus it probably does not make a lot of sense to keep it in the Debian
+    menu.
+
+  * debian/control:
+    - Drop dependency on pre-jessie util-linux version.
+    - Bump standard-version to 4.0.0 (no changes required).
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Fix the leading comment which mentioned “vm” despite the fact that the
+    test runs in a container.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 19 Jun 2017 02:30:10 +0200
+
+chrony (3.1-3) experimental; urgency=medium
+
+  * debian/chrony.if-{post-down,up}:
+    - Remove unnecessary “else” statements.
+
+  * debian/chrony.ppp.ip-down:
+    - Don’t check and delete “/var/run/chrony-ppp-up”, that file doesn’t exist
+    anymore.
+    - Check for pid file existence instead of calling “pidof”.
+
+  * debian/chrony.ppp.ip-up:
+    - Don’t create “/var/run/chrony-ppp-up” file after the ppp link came up.
+    - Check for pid file existence instead of calling “pidof”.
+    - Don’t call “chronyc” using its absolute path.
+    - Check for the presence of a default route before advising “chronyd” that
+    the network connectivity to the sources is ready.
+
+  * debian/init:
+    - Check if “$PIDFILE” exists before taking action.
+    - Do not print informational messages.
+    - Remove the “chronyd” pid file when stopping as it doesn’t do it on
+    its own.
+    - Rework the “restart|force-reload” pattern.
+    - Make use of some init-functions.
+    - Print a message if “chronyd” is already running while attempting to start
+    it.
+    - Do not delete “/var/run/chrony-ppp-up”, that file doesn’t exist anymore.
+
+  * d/rules:
+    - Move the default pid file from “/var/run” to “/run”.
+
+  * d/tests/*:
+    - Use autopkgtest facility to run the upstream simulation test suite.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 14 May 2017 17:26:15 +0200
+
+chrony (3.1-2) experimental; urgency=medium
+
+  * Merge branch 'master' into experimental. (Closes: #861258)
+
+  * debian/patches/*:
+    - Remove the “fix_time_smoothing_in_interleaved_mode.patch” patch. Not
+    needed anymore.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 26 Apr 2017 21:17:43 +0200
+
+chrony (3.1-1) experimental; urgency=medium
+
+  * Import upstream version 3.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.conf:
+    - Remove the “hwclockfile” directive. Unneeded now that the configure
+    script allows us to set the default path to the adjtime file via the
+    “--with-hwclockfile” option.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/rules:
+    - Specify default path to hwclock adjtime file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 02 Feb 2017 19:24:30 +0100
+
+chrony (3.0-4) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Backport commit 768bce799bfe to make chrony operable with the syscall
+    filtering feature enabled in level 1. (Closes: #861258)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 26 Apr 2017 17:39:44 +0200
+
+chrony (3.0-3) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Backport an upstream patch to fix time smoothing in interleaved mode.
+    (Closes: #854424)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 07 Feb 2017 00:37:24 +0100
+
+chrony (3.0-2) unstable; urgency=medium
+
+  * debian/chrony.conf:
+    - Disable logging by default, it waste some disk space and users are
+    probably better served by “chronyc sources” and “chronyc sourcestats”
+    commands anyway.
+
+  * debian/chrony.service:
+    - Remove the “Restart=on-failure” option. There are possible security
+    implications for NTP clients.
+
+  * debian/dirs:
+    - Add etc/logrotate.d to avoid build failure.
+
+  * Remove our logrotate configuration file in favour of the upstream’s one.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 Jan 2017 15:26:31 +0100
+
+chrony (3.0-1) unstable; urgency=medium
+
+  * Import upstream version 3.0:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * Merge branch “experimental”:
+    - Enable support for MS-SNTP authentication in Samba.
+    - Rename --chronysockdir to --chronyrundir.
+    - Enable seccomp facility on powerpcspe.
+
+  * debian/chrony.conf:
+    - Make use of the “makestep” directive to step the system clock instead of
+    slewing it when necessary.
+    - Drop the “offline” option as per upstream’s advice to render chrony’s
+    start-up sequence safer.
+
+  * debian/chrony.service:
+    - Reflect init-helper script deletion.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2017.
+    - Adjust copyright holders and update some copyright years. Kudos to Paul
+    Gevers <elbrus@debian.org> for spotting the necessary updates.
+
+  * debian/init:
+    - Reflect init-helper script deletion.
+
+  * debian/install:
+    - Don’t install the init-helper script, it has been deleted.
+
+  * debian/README.Debian:
+    - Remove obsolete information.
+
+  * Remove the init-helper script as it no longer needed.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 17 Jan 2017 22:05:31 +0100
+
+chrony (3.0~pre3-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 06 Jan 2017 14:20:13 +0100
+
+chrony (3.0~pre2-2) experimental; urgency=low
+
+  * Merge branch “master”.
+
+  * Enable seccomp facility on powerpcspe.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 03 Jan 2017 18:17:13 +0100
+
+chrony (3.0~pre2-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 15 Dec 2016 15:23:44 +0100
+
+chrony (3.0~pre1-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/copyright:
+    - Mention new files.
+
+  * debian/rules:
+    - Enable support for MS-SNTP authentication in Samba.
+    - Rename --chronysockdir to --chronyrundir.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 10 Dec 2016 16:30:19 +0100
+
+chrony (2.4.1-3) unstable; urgency=medium
+
+  * debian/apm:
+    - Removing that script as APM as been replaced by ACPI long time ago, thus
+    it’s highly probable that it isn’t useful anymore.
+
+  * debian/chrony.maintscript:
+    - Remove the apm script’s conffile.
+
+  * debian/chrony.service:
+    - Supply a systemd service file.
+    - Update unit section’s description. Add chronyc and chrony.conf man pages
+    information and remove reference to “/usr/share/doc/chrony.txt.gz” which
+    is not generated anymore.
+    - Update unit section’s documentation.
+
+  * debian/dirs:
+    - Don’t create etc/apm/event.d as the apm script isn’t provided anymore.
+
+  * debian/init:
+    - Convert to use the init-helper script.
+
+  * debian/init-helper:
+    - Add a helper script that will be used to maintain feature parity between
+    the SysV script and the systemd service file.
+
+  * debian/install:
+    - Install the init-helper script in “/usr/lib/chrony”.
+
+  * debian/rules:
+    - Don’t install the now removed apm script.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 22 Dec 2016 02:16:54 +0100
+
+chrony (2.4.1-2) unstable; urgency=medium
+
+  * debian/chrony.conf:
+    - Don’t create sample histories by default. Using that feature does not
+    make a lot of sense when using a pool of rapidely rotating time servers.
+    - Remove unused directives.
+    - Improve (well, I hope! ;-) ) the configuration file readability.
+    - Reword the driftfile directive commentary.
+    - Shorten the lead-in comment.
+
+  * debian/control:
+    - Build-depend on pps-tools only on linux.
+    - Remove libnss3-dev from Build-Depends until #846012 is fixed.
+
+  * debian/init:
+    - Don’t pass the “-r” option when restarting chronyd as we have disabled
+    the creation of sample histories by default.
+
+  * debian/rules:
+    - Drop dh_auto_build override. Nowadays, the documentation is built by
+    default.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 9 Dec 2016 16:58:32 +0100
+
+chrony (2.4.1-1) unstable; urgency=medium
+
+  * Import upstream version 2.4.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.default:
+    - New file used to pass options to chronyd. Thanks to nutzteil
+    <nutzteil@web.de> for the suggestion and the initial patch.
+    (Closes: #834240)
+
+  * debian/compat:
+    - Bump to debhelper compat 10.
+
+  * debian/control:
+    - Build depend on debhelper ≥ 10.
+
+  * debian/copyright:
+    - Use HTTPS for all URI.
+
+  * debian/init:
+    - Read and execute options assigned to the “DAEMON_OPTS” variable.
+
+  * debian/rules:
+    - Drop dh “--parallel” option. Enabled by default in debhelper 10.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 21 Nov 2016 12:58:05 +0100
+
+chrony (2.4-1) unstable; urgency=medium
+
+  The “Fix decade-old bug reports” release.
+
+  * Import upstream version 2.4:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.if-{up,post-down}:
+    - New scripts used to put chronyd online/offline depending on the
+    state of the connection. (Closes: #240528,#312092,#389961)
+
+  * debian/chrony.keys:
+    - Highlight “chronyc keygen” command to generate keys.
+
+  * debian/chrony.ppp.ip-down:
+    - Be sure that there is no default route before going offline.
+    (Closes: #252131)
+
+  * debian/control:
+    - Remove install-info dependency.
+    - Remove texinfo build dependency since documentation in Texinfo format
+    has been dropped upstream.
+    - Build depend on asciidoctor ≥ 1.5.3-1~. The version constraint is
+    important since chrony’s man pages are generated from “adoc” files, a
+    functionality that has been added in asciidoctor 1.5.3.
+
+  * debian/dirs:
+    - Add “etc/NetworkManager/dispatcher.d”.
+
+  * debian/doc-base:
+    - Remove the file since we do not generate chrony.{html,txt} anymore.
+
+  * debian/docs:
+    - Remove references to chrony.{html,txt}.
+
+  * debian/patches/*:
+    - Drop fix-ftbfs-on-powerpc-ppc64-ppc64el.diff; applied upstream.
+    - Update the “series” file accordingly.
+
+  * debian/postinst:
+    - Use ucfr to associate chrony with its configuration files. Suggested by
+    Paul Gevers <elbrus@debian.org>
+
+  * debian/postrm:
+    - Remove all vestiges of the association between chrony and its
+    configuration files. Also suggested by Paul Gevers <elbrus@debian.org>
+
+  * debian/rules:
+    - Provide upstream NetworkManager dispatcher script.
+
+  * debian/watch:
+    - Use HTTPS to fetch new upstream releases.
+    - Switch to version 4 format.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 17 Jun 2016 17:20:08 +0200
+
+chrony (2.3-2) unstable; urgency=low
+
+  * Cherry pick upstream patch to fix FTBFS on PowerPC, ppc64 and ppc64el
+    architectures.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 20 May 2016 14:21:14 +0200
+
+chrony (2.3-1) unstable; urgency=low
+
+  * Import upstream version 2.3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+    (Closes: #818235)
+
+  * debian/chrony.conf:
+    - Drop the “logchange” directive. Upstream has enabled “logchange” by
+    default with a threshold of 1 second. We now use that instead of our custom
+    threshold of 0,5 second which tended to spam syslog.
+    - Remove obsolete comment.
+
+  * debian/chrony.lintian-overrides:
+    - Update “chrony.keys” path
+
+  * debian/control:
+    - Bump standard-version to 3.9.8 (no changes required).
+    - Use HTTPS transport protocol for the homepage URL.
+
+  * debian/copyright:
+    - Add some entries about new or untracked files.
+
+  * debian/postinst:
+    - Move /usr/share/chrony/chrony.keys template to /etc/chrony using ucf.
+    - Avoid displaying needless prompt when upgrading to chrony ≥ 2.2.1-1.
+    (Closes: #820087)
+
+  * debian/postrm:
+    - Remove chrony.keys on purge.
+    - Remove all vestiges of chrony.keys from the state hashfile.
+
+  * debian/rules:
+    - Re-enable test suite.
+    - Remove dh_installinit override. The init script is LSB-compliant so
+    passing the “default” option or the two-digit sequence number is unneeded.
+    - Explicitly set the NTP era. With this change, the NTP time will be
+    mapped from 1970-01-01T00:00:00Z to 2106-02-07T06:28:16Z. Thanks to this
+    fixed value, chrony build should be reproducible.
+    - Move the key file template (chrony.keys) in /usr/share/chrony.
+    - Force /usr/share/chrony/chrony.keys to use 0640 modes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 May 2016 23:13:05 +0200
+
+chrony (2.2.1-1) unstable; urgency=medium
+
+  * Import upstream versions 2.2 and 2.2.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+    - The 2.2.1 release version fixes CVE-2016-1567. (Closes: #812923)
+
+  * debian/chrony.conf:
+    - Drop the commandkey directive. It is obsolete since the introduction of a
+    Unix domain command socket in chrony 2.2.
+    - Fix keyfile directive commentary.
+
+  * debian/chrony.keys:
+    - New file template.
+
+  * debian/chrony.lintian-overrides:
+    - New file used to force lintian to stop complaining about the “chrony.keys”
+    file modes (0640).
+
+  * debian/chrony.ppp.ip-down:
+    - Drop obsolete authentication method to the chronyd daemon. This is now
+    handled by the usage of a Unix domain command socket.
+
+  * debian/chrony.ppp.ip-up:
+    - Drop obsolete authentication method to the chronyd daemon. This is now
+    handled by the usage of a Unix domain command socket.
+    - Reinstate the “burst” chronyc command.
+
+  * debian/control:
+    - Build depend on libseccomp-dev ≥ 2.2.3-3~. We need it to provide syscall
+    filtering.
+    - Fix a typo relative to the name of an architecture.
+    - Build depend on pkg-config.
+    - Restrict libcap-dev build dependency on Linux only.
+    - Depend on iproute2 instead of net-tools.
+    - Drop timelimit dependency.
+    - Update Vcs-Git to use HTTPS.
+    - Bump standard-version to 3.9.7 (no changes required).
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/init:
+    - Make use of “ip r” instead of “netstat -rn”. (Closes: #818234)
+    - Delete unused “FLAGS” variable.
+    - Do not execute ip and chronyc through timelimit.
+    - Don’t call chronyc using its absolute path.
+    - Check if the value of the DAEMON variable is executable.
+    - Drop the two seconds delay as it should be unnecessary.
+    - Drop obsolete authentication method from the putonline() function.
+    - Fix indentation issue in the putonline() function.
+
+  * debian/logrotate:
+    - Do not pass the “-a” option to chronyc, it’s no longer necessary.
+
+  * debian/NEWS:
+    - Add a comment about the command key suppression from the “chrony.keys”
+    file.
+
+  * debian/patches/:
+    - Drop 01_do-not-install-copying-file.patch, not needed anymore.
+      ↳ Remove reference to that patch from the series file.
+
+  * debian/postinst:
+    - Do not create an ID/key pair for command authentication. Configuration
+    and monitoring via chronyc is now done using Unix domain socket accessible
+    by root or by the system user to which chronyd will drop root privileges,
+    i.e. _chrony.
+
+  * debian/postrm:
+    - Remove /var/lib/chrony content only on purge. (Closes: #568492)
+
+  * debian/README.Debian:
+    - Drop obsolete statement.
+
+  * debian/rules:
+    - Build with --enable-scfilter.
+    - Install the “chrony.keys” file in /etc/chrony/ with 0640 modes.
+    - Override dh_fixperms to prevent it from modifying modes of the
+    “chrony.keys” file. By default, dh_fixperms tries to set the default modes
+    (0644).
+    - Move the “chronyd.sock” file from /var/run/chrony to /run/chrony.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 19 Mar 2016 14:42:23 +0100
+
+chrony (2.1.1-1) unstable; urgency=medium
+
+  * Import upstream version 2.0 and 2.1.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/:
+    - Rename ppp scripts from ip-{up,down} to chrony.ppp.ip-{up,down}.
+    Necessary to let dh_installppp do its magic.
+
+  * debian/chrony.conf:
+    - Use the new 'pool' directive to specify the pool of NTP servers.
+    - Use the iburst option to speed up the initial synchronization.
+    - Drop the minpoll option. There is no point to deviate from upstream here.
+    Consequently, the default minimum polling interval is now 64 seconds
+    instead of 256 seconds.
+    - Enable kernel synchronization of the RTC via the 'rtcsync' directive.
+    - Drop the commented out 'rtcfile' directive in the configuration file.
+    - Stricly act as an NTP client by default. Serving time to other systems
+    should be the decision of the administrator(s). (Closes: #778770)
+    - Clarify some comments.
+    - Improve comment about the 'commandkey' directive.
+
+  * debian/control:
+    - Drop 'Recommends: udev (>= 0.124-1)' since it predates Debian squeeze.
+
+  * debian/copyright:
+    - Update copyright years.
+    - Various cleanups.
+    - Update relative to sys_macosx.{c,h} files.
+    - The test/simulation/test.common file is under the GPL-2+ license.
+    Thanks to Paul Gevers <elbrus@debian.org> for catching it.
+
+  * debian/NEWS:
+    - Comment the deactivation of the NTP server capability by default.
+
+  * debian/patches/:
+    - Refresh 01_do-not-install-copying-file.patch.
+
+  * debian/README.Debian:
+    - Fix misleading information.
+
+  * debian/rules:
+    - No need to install ppp scripts from the 'rules' script. Let dh_installppp
+    handle that.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 Nov 2015 00:11:23 +0100
+
+chrony (1.31.1-2) unstable; urgency=medium
+
+  * Rename the NEWS.Debian file to NEWS. dh_installchangelogs doesn’t seems
+    to be able to deal with the former name.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 17 Sep 2015 21:50:30 +0200
+
+chrony (1.31.1-1) unstable; urgency=medium
+
+  * Import upstream version 1.31 and 1.31.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for release notes.
+
+  * debian/chrony.conf:
+    - Use the 'hwclockfile' directive. Avoid using text processing methods in
+    the post install script to find out if the RTC keeps local time or UTC.
+    (Closes: #778710)
+
+  * debian/clean:
+    - Add getdate.c
+
+  * debian/control:
+    - Move chrony from admin to net section.
+    - Change priority from extra to optional.
+    - Build depends on libcap-dev. (Closes: #768803)
+    - Bump standards-version to 3.9.6 (no changes required).
+    - Set myself as maintainer and Joachim as uploader.
+    - Update Vcs-Browser URL to use cgit and https.
+    - Build depends on pps-tools. Provides PPSAPI (RFC-2783) support.
+    - Improve the synopsis.
+    - Depend on util-linux (>= 2.20.1-5). Ensure that the 'UTC=' setting
+    from the '/etc/default/rcS' file have been migrated to UTC/LOCAL in
+    '/etc/adjtime'.
+    - Depends on adduser. Needed to create "_chrony" system user/group.
+
+  * debian/copyright:
+    - Add myself to copyright holders.
+    - Remove spaces from short name license (fix Lintian warning)
+    - Filled short license field (RSA-MD) (fix Lintian warning)
+    - Move comment to the "Comment:" field
+
+  * debian/logrotate:
+    - Simplify postrotate script. Thanks to Frédéric Brière
+    <fbriere@fbriere.net> for reporting and diagnosing the issue.
+    (Closes: #763542)
+
+  * debian/patches:
+    - Drop patches for issues fixed upstream.
+    - Rename and update patch. Update the series file accordingly.
+
+  * debian/postinst:
+    - Pass the '--three-way' option to ucf.
+    - Remove useless text processing methods as we now use the 'hwclockfile'
+    directive. (Closes: #778711)
+    - Create "_chrony" system user/group.
+    - Update the "new_file" path in the ucf invocation.
+    - Remove the MAILPASSWORD shell variable as we don’t use it.
+
+  * debian/postrm:
+    - Drop removal instruction of /etc/cron.weekly/chrony.
+    - Remove "_chrony" system user/group on purge.
+    - Don’t pass the --group option to deluser.
+
+  * debian/NEWS.Debian:
+    - New file incorporating worthwhile changes in this release.
+
+  * debian/README.Debian:
+    - Fix typo, thanks to Paul Gevers <elbrus@debian.org> for catching it.
+    - Missing word added.
+
+  * debian/rules:
+    - Build with all hardening flags.
+    - Ease the reading of configure options.
+    - Specify "_chrony" as default chronyd user. This is the system user to
+    which chronyd will drop root privileges. You'll find further information
+    in /usr/share/doc/chrony/README.Debian.
+    (Closes: #688971)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 6 Sep 2015 22:39:22 +0200
+
+chrony (1.30-2) unstable; urgency=medium
+
+  * With the following security bugfixes (Closes: #782160):
+    - Fix CVE-2015-1853: Protect authenticated symmetric NTP
+                         associations against DoS attacks.
+    - Fix CVE-2015-1821: Fix access configuration with subnet
+                         size indivisible by 4.
+    - Fix CVE-2015-1822: Fix initialization of reply slots for
+                         authenticated commands.
+  * debian/control:
+   - Update e-mail address of myself.
+   - Add Vincent Blut as co-maintainer.
+
+ -- Joachim Wiedorn <joodebian@joonet.de>  Fri, 10 Apr 2015 11:41:31 +0200
+
+chrony (1.30-1) unstable; urgency=medium
+
+  * New upstream release with following bugfixes:
+    - Fix crash when selecting with multiple preferred sources.
+    - Fix frequency calculation with large frequency offsets.
+    - Fix code writing drift and RTC files to compile correctly.
+    - Fix -4/-6 options in chronyc to not reset hostname set by -h.
+    - Fix refclock sample validation with sub-second polling interval.
+    - Set stratum correctly with non-PPS SOCK refclock and local stratum.
+    - Modify dispersion accounting in refclocks to prevent PPS getting
+        stuck with large dispersion and not accepting new samples.
+    - Move faq.txt (PHP style) to a plain text file FAQ. Closes: #415729
+
+  * Add gpg signature of upstream developer for use with uscan.
+  * Update debian/watch, add check of upstream gpg signature.
+  * Update all patches.
+
+  * Bugfix: Use /etc/adjtime in postinst script to recognize
+      UTC hardware clock.  Closes: #680498
+  * Use logrotate instead of cron script. Closes: #323966
+  * debian/rules: disable test simulation.
+
+  * debian/control: remove obsolete build dependency to dpkg-dev.
+  * debian/install, debian/dirs, debian/clean: Update.
+  * debian/copyright: Update and add entries.
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Sun, 10 Aug 2014 19:10:35 +0200
+
+chrony (1.29.1-1) unstable; urgency=high
+
+  * New upstream release with bugfix:
+    - Closes: #737644: Fixing vulnerability:
+        CVE-2014-0021 - traffic amplification in cmdmon protocol
+        (incompatible with previous protocol version, but chronyc
+        supports both).
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Thu, 06 Feb 2014 15:51:47 +0100
+
+chrony (1.29-1) unstable; urgency=medium
+
+  * New upstream release with some bugfixes:
+    - Closes: #719132: new upstream version, fixes security bugs.
+    - Closes: #719203: Fixing vulnerabilities:
+        CVE-2012-4502 - Buffer overflow,
+        CVE-2012-4503 - Uninitialized data.
+
+  * debian/control:
+    - Set myself as new maintainer. Closes: #705768
+    - Bump to Standards-Version 3.9.5.
+    - Move to debhelper >= 9 and compat level 9.
+    - Update package descriptions.
+    - Add Vcs fields to new git repository.
+    - Add dependency to lsb-base (for init script).
+    - Add build dependency to libtomcrypt-dev.
+  * Move to source format 3.0 (quilt).
+  * Add the following patch files:  (Closes: #637514)
+    - 01_fix-small-typo-in-manpages
+    - 03_recreate-always-getdate-c
+    - 04_do-not-look-for-ncurses    (Closes: #646732)
+    - 05_disable-installation-of-license
+  * debian/rules:
+    - Move to dh-based rules file.
+    - Enable parallel builds.
+
+  * Add debian/watch file.
+  * Full update of debian/copyright file.
+  * Add debian/doc-base file.
+  * Full update of debian/README.Debian file.
+  * Update debian/postinst, debian/postrm, debian/prerm.
+  * Remove obsolete debian/preinst. Reduce mailing within postinst.
+  * Do not use old md5sum file anymore for ucf in postinst script.
+  * Add status action in init script (debian/init). Closes: #652207
+  * Add debian/install file for installing example of chrony.conf.
+  * Reduce debian/dirs file for use with debhelper 9.
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Fri, 20 Dec 2013 23:35:25 +0100
+
+chrony (1.26-4) unstable; urgency=low
+
+  * QA upload.
+  * Depend on net-tools, for netstat (closes: #707260).
+
+ -- Colin Watson <cjwatson@debian.org>  Mon, 08 Jul 2013 18:00:45 +0100
+
+chrony (1.26-3) unstable; urgency=low
+
+  * Orphaned.
+
+ -- John G. Hasler <jhasler@debian.org>  Fri, 19 Apr 2013 13:08:31 -0500
+
+chrony (1.26-2) unstable; urgency=low
+
+  * Fixed Makefile.in so that getdate.c gets made (and removed
+    in "clean").  This will go upstream.  Moved faq stuff in rules
+    from binary-indep to binary-arch.
+  * Restored accidently deleted nmu changelog entry.
+
+  * Applied patch from Moritz Muehlenhoff <jmm@debian.org>
+    Closes: #655123 Please enabled hardened build flags
+
+  * Fixed upstream.
+    Closes: #518385 Chrony segfaults on startup (narrowed down to
+    chronyc and "burst")
+
+  * Added DEB_BUILD_OPTIONS=noopt to rules.
+    Added build-arch and build-indep to rules.
+    Prefix is now 'usr'.
+    Changed to dh_installman.
+    Fixed "clean:" target.
+    Closes: #479389 Improvements for debian/rules
+
+  * Fixed upstream.
+    Closes: #195620 Strange "System time : xxx seconds slow of NTP time"
+    output
+
+  * Upstream changes should have fixed this.
+    Closes:#294030 chronyd makes the whole system briefly (< 1 second)
+    freeze
+
+  * Fixed by upstream changes and new LSB headers.
+    Closes: #407466 Chrony won't access hardware clock but prevents
+    hwclock from doing so either
+
+ -- John G. Hasler <jhasler@debian.org>  Sun, 01 Jul 2012 22:05:56 -0500
+
+chrony (1.26-1) unstable; urgency=low
+
+  * New upstream release
+    Closes: #348554: chrony and hwclock packages not coordinated.
+    Closes: #572964: RTC support is missing.
+    Closes: #642209: add RTC support for linux 3.0.
+    Closes: #644241: new upstream version 1.26 available.
+
+  * Applied patches from Joachim Wiedorn <ad_debian@joonet.de>:
+    Fixed several typos in man pages and README.
+    Added version.h.
+    Moved default chrony.conf to debian/ .
+    Renamed cron and init files.
+    Removed debian/NEWS.Debian, debian/info.
+    Added debian/clean.
+    Updated debian/copyright.  COPYING stays.  Upstream requires it.
+    Fixed debian/menu, debian/control, updated debian/compat.
+    Added "--without-readline" to debian/rules: rewrite later.
+    Minor fixes to initscript: rewrite later.
+
+    Closes: #646732 Move from readline support to editline support.
+    Closes: #598253 Fix typo in LSB init headers ($hwclock to $time).
+    Closes: #600403 Fix init check with PPP connection.
+
+ -- John G. Hasler <jhasler@debian.org>  Sun, 17 Jun 2012 21:55:47 -0500
+
+chrony (1.24-3.1) unstable; urgency=low
+
+  * Non-maintainer upload.
+  * Add patch (directly over the source...), to work with kernels > 3.0.0,
+    by Paul Martin at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=628919#15.
+    (Closes: #628919)
+  * Fix readline build-depends from "libreadline5-dev | libreadline-dev" to
+    libreadline-gplv2-dev because chrony is GPLv2 only.  (Closes: #634447)
+  * Update copyright file to say that chrony is GPLv2 only. (Closes: #637526)
+
+ -- Ana Beatriz Guerrero Lopez <ana@debian.org>  Fri, 12 Aug 2011 12:32:26 +0200
+
+chrony (1.24-3) unstable; urgency=high
+
+  * Applied (modifed) patch from Gregor Herrmann.
+
+    Closes: #593145: fails to configure on installation
+    Closes: #552162: chrony incorrectly thinks that it has failed to
+    (re)start
+    Closes: #592930: invoke-rc.d: initscript chrony, action "start" failed.
+
+ -- John G. Hasler <jhasler@debian.org>  Tue, 14 Sep 2010 10:06:47 -0500
+
+chrony (1.24-2) unstable; urgency=low
+
+  * Fixed regression that caused default CHRONY_IOC_ lines to
+    vanish from io_linux.h thereby breaking hppa and ia64.
+
+    Closes: #588930: FTBFS [ia64,hppa]: "I don't know the values of the
+    _IOC_* constants on your architecture"
+
+  * $remote_fs was added in 1.24-1.  Depending on networking is neither
+    necessary nor desireable.
+
+    Closes: #590888: Dependencies on init.d script insuficcient
+
+  * Still need to rewrite scripts.
+
+ -- John G. Hasler <jhasler@newsguy.com>  Fri, 30 Jul 2010 20:32:55 -0500
+
+chrony (1.24-1) unstable; urgency=low
+
+  * New upstream release.  The scripts will be rewritten and many more bugs
+    taken care of in -2.  Right now I want to get 1.24 out there.
+
+  * Applied patch from Petter Reinholdtsen to init.d
+
+    Closes: #541806: misses syslog dependency in LSB headers
+
+  * Chrony cannot be linked to libreadline6 because it is GPLv2 only.
+
+    Closes: #553739 replacing libreadline5-dev build dependency with
+    libreadline-dev
+
+  * "configure" rewritten upstream, eliminating "+=".
+
+    Closes: #573036: RTC support disabled (due to Bashism in configure line 293)
+
+  * Removed "install-info" from scripts.
+
+    Closes: #568703: dpkg warnings
+
+  * client.c has been rewritten upstream.
+
+    Closes: #573032
+
+  * Fixed typos.
+
+    Closes: #434629: 'man chrony', 'cronyc', 'cronyd' typos: "parateters" x 2,
+    "priviliges"
+
+  * Added debian/source/format containing "1.0".
+
+ -- John G. Hasler <jhasler@newsguy.com>  Tue, 22 Jun 2010 16:01:29 -0500
+
+chrony (1.23-7) unstable; urgency=high
+
+  * Applied patches from upstream to fix remote DOS:
+
+    CVE-2010-0292 Don't reply to invalid cmdmon packets
+
+    CVE-2010-0293 Limit client log memory size
+
+    CVE-2010-0294 Limit rate of syslog messages
+
+ -- John G. Hasler <jhasler@newsguy.com>  Tue, 02 Feb 2010 19:37:50 -0600
+
+chrony (1.23-6) unstable; urgency=low
+
+  * Commented out rtcfile directive in chrony.conf because it can cause
+    lockups with certain combinations of motherboard and kernel (this is
+    a known kernel bug).
+
+    Closes: #508298: chronyd unreachable and does not work (clock drifts)
+
+  * Chrony no longer uses the ppp/ip-up.d and ppp/ip-up.d files and the new
+    init.d file won't hang if chronyc hangs.
+
+    Closes: #448481: /etc/ppp/ip-up.d/chrony doesn't work when bindaddress is set.
+
+  * Cannot reproduce on current version on amd64.
+
+    Closes: #412961: error in tracking report (on amd64?)
+
+ -- John Hasler <jhasler@debian.org>  Wed, 10 Dec 2008 14:16:37 -0600
+
+chrony (1.23-5) unstable; urgency=low
+
+  * Replaced background kill with 'timelimit' in initscript.
+
+    Closes: #505094: chrony: kills random netstat processes
+
+  * Added 'Recommends: udev (>= 0.124-1)'
+
+    Closes: #497113: /dev/rtc renamed to /dev/rtc0 with linux-image-2.6-*/2.6.26+15
+
+  * Had previously applied patch from Nathanael Nerode to fix configure
+    bug but forgot to close the bug.
+
+    Closes: #392273: Recursive dependency disease: chrony shouldn't depend on ncurses
+
+ -- John Hasler <jhasler@debian.org>  Sun, 09 Nov 2008 20:19:22 -0600
+
+chrony (1.23-4) unstable; urgency=low
+
+  * Fixed dependency of init script on Pppconfig ip-up.d script by moving
+    those lines into the init script.
+
+  * Added checks to try to make sure that Chronyd is really, really running.
+    Changed Netstat call to use -n, added code to kill it if it hangs.
+    Added code to kill Chronyc if it can't contact Chronyd.
+    Discussed the HPET/rtc problem in NEWS.Debian.
+
+    Closes: #504000: init script hangs for a while might break upgrade
+
+  * Added missing initialization to create_instance() in ntp_core.c.
+    This was why UTI_NormaliseTimeval() was being called with huge
+    values at times.
+
+  * See comment on #195620 in 1.21z-6 below.  If you know of more LP64
+    bugs reopen #348412 with a patch.
+
+    Closes: #348412: chronyc not LP64 compliant
+
+  * Added comment about sources being discarded to chrony.conf as suggested
+    by Andreas Hübner in  #268289.
+
+  * This is normal behavior.
+
+    Closes: #287060: trimrtc takes 40 seconds to take effect
+
+ -- John Hasler <jhasler@debian.org>  Thu, 06 Nov 2008 10:38:58 -0600
+
+chrony (1.23-3) unstable; urgency=high
+
+  * Rewrote UTI_NormaliseTimeval()in util.c to use divide/remainder
+    instead of loops at the suggestion of Gabor Gombas.  This prevents the
+    problem of the loop running until the sun goes out when the function
+    is called with a very large value for tv_usec on 64-bit architectures.
+    Also fixed some other spots where the same loop was being used.
+
+    Closes: #474294 Goes into endless loop
+    Closes: #447011 chronyd stalls with 100% CPU usage
+
+    I still don't know why the function is being called with such a
+    large value, however.
+
+  * Changed default servers in chrony,conf to Debian servers.
+
+    Closes: #434483: chrony: Should use NTP servers in Debian pool
+
+ -- John Hasler <jhasler@debian.org>  Sat, 26 Apr 2008 11:47:44 -0500
+
+chrony (1.23-2) experimental; urgency=low
+
+  * Added default IOC's to io_linux.h.
+    Closes: #477043: chrony_1.23-1(ia64/experimental): FTBFS: IOC
+    constants unknown on ia64
+    Closes: #476963: chrony_1.23-1(hppa/experimental): FTBFS: "I don't
+    know the values of the _IOC_* constants for your architecture"
+
+ -- John Hasler <jhasler@debian.org>  Sun, 20 Apr 2008 13:29:29 -0500
+
+chrony (1.23-1) experimental; urgency=low
+
+  * New upstream release
+    This is 1.23 with Debian patches applied (including some for LP64).
+    I'm uploading this to Experimental to get it tested on x86_64 to see
+    if  #474294 is fixed.
+
+ -- John Hasler <jhasler@debian.org>  Sat, 19 Apr 2008 14:49:15 -0500
+
+chrony (1.21z-6) unstable; urgency=low
+
+  * Applied patches from Eric Lammerts <eric@lammerts.org> and Goswin von
+    Brederlow <brederlo@informatik.uni-tuebingen.de> to cast the value
+    returned by ntohl to int32_t and so cause correct sign-extension near
+    line 1655 in client.c.  Also fixed similar bugs in the same area.  I'm
+    not sure this entirely fixes the chronyc number display problem,
+    though.  I've not closed #348412 here because chrony is still not
+    fully LP64 compliant.
+    Closes: #195620: Strange "System time : xxx seconds slow of
+    NTP time" output
+
+  * Replaced addrfilt.c with addrfilt.c from upstream git repository.
+    This fixes the recursive structure definition problems.
+
+  * Replaced 'route' with 'netstat -r' in the initscript.
+
+  * Applied patch for configure script from Nathanael Nerode
+    <neroden@gcc.gnu.org> to delete the superfluous "lncurses" at line
+    327.
+    Closes: #392273: Recursive dependency disease: chrony shouldn't depend
+    on ncurses
+
+  * Added test to reject servers claiming stratum less than 1 in
+    ntp_core.c "Test 7".  Bill Unruh <unruh@physics.ubc.ca> has run across
+    a server that sometimes claims to be stratum 0, which causes
+    considerable confusion.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 16 Feb 2007 17:47:40 -0600
+
+chrony (1.21z-5) unstable; urgency=high
+
+  * Applied postinst patch from Lionel Elie Mamane to test for the
+    existence of old .keys and .conf files before renaming them.
+    Closes: #397759: fails to configure: mv: cannot stat `/etc/chrony/chrony.keys.1.21-2':
+    No such file or directory
+
+  * Added burst command to /etc/ppp/ip-up.d/chrony to give chronyd a kick in the butt.
+    Shouldn't need that, though.
+    Initscript now calls /etc/ppp/ip-up.d/chrony if a default route exists.
+    Closes: #397739: Not connecting to sources after reboot - dialup
+
+ -- John Hasler <jhasler@debian.org>  Sun, 26 Nov 2006 08:07:20 -0600
+
+chrony (1.21z-4) unstable; urgency=low
+
+  * Added test for /usr/bin/mail to postinst.
+    Closes: #386651: chrony: Requires /usr/bin/mail but doesn't depend on it
+    Closes: #390280: chrony: missing dependency on mail
+
+  * Added LSB headers to initscript
+
+  * Corrected erroneous use of 'dpkg --compare-version' in preinst and postinst.
+    Closes: #386733: fails to configure (bad upgrade check)
+
+  * Added rm to postinst to remove keyfile possibly left by a failed install.
+    Closes: #390278: usage of tempfile /etc/chrony/chrony.keys is doubtful
+
+ -- John Hasler <jhasler@debian.org>  Sat,  7 Oct 2006 13:39:49 -0500
+
+chrony (1.21z-3) unstable; urgency=low
+
+  * Changed upstream version number from 1.21 to 1.21z to satisfy Debian
+    archive software.
+
+  * Replaced impure chrony_1.21.orig.tar.gz.
+    Closes: #340030: chrony: Tarball is impure
+
+  * Now Provides, Conflicts, Replaces time-daemon
+    Closes: #330839: time-daemon pseudopackage
+
+  * Corrected typos.
+    Closes: #321121: chrony: typo in 'Conflicts:' field: s/ntpsimple/ntp-simple/ and s/ntprefclock/ntp-refclock/
+
+  * Rewrote postinst and postrm to use ucf.  Wrote preinst to protect chrony.conf from dpkg.
+    Closes: #351332: chrony: conffile change prompt prevents smooth upgrade from sarge to etch
+
+  * Deleted last few lines of chrony.conf as they no longer apply.
+
+  * Deleted .arch-ids from contrib and examples.
+
+  * Fixed typo in chronyc.1
+    Closes: #349871: chrony: typo in chrnoyc.1 results in missing word
+
+  * Corrected references in man pages.
+    Closes: #345034: chrony: man pages refer to wrong sections
+
+  * Added "allow 172.16/12" to chrony.conf.
+    Closes: #252952: chrony: default allow should also have 172.16/12
+
+  * Channged server lines in chrony.conf to follow ntp.org current recommendation.
+    Closes: #243534: chrony: new pool.ntp.org setup doesn't work well
+
+  * Fixed FSF address in debian/copyright.
+
+ -- John Hasler <jhasler@debian.org>  Fri,  1 Sep 2006 10:52:52 -0500
+
+chrony (1.21-2) unstable; urgency=high
+
+  * Patched io_linux.h to add missing architectures.
+    Closes: #339764: chrony - FTBFS: #error "I don't know the values of the
+    _IOC_* constants for your architecture"
+
+  * Fixed brown-bag error in rules.
+    Closes: #339853: /usr/sbin/chronyd is missing
+
+ -- John Hasler <jhasler@debian.org>  Sat, 19 Nov 2005 10:12:49 -0600
+
+chrony (1.21-1) unstable; urgency=low
+
+  * New upstream release
+    Closes: #328292: New version of chrony avalaible
+    Closes: #301592: Fails to read RTC and floods logfiles
+
+  * Enabled RTC as upstream has installed a work-around for the HPET bug.
+
+  * Switched to libreadline5.
+    Closes: #326379: please rebuild with libreadline5-dev as build dependency
+
+  * Patched addrfilt.c to fix gcc 4.0 build problem.
+    Closes: #298709: chrony: FTBFS (amd64/gcc-4.0): array type has incomplete element type
+
+  * There are lots more minor things to fix but I'm uploading now to close
+    the serious bugs.  I'll upload another version with some improvements
+    in a few weeks.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 15 Nov 2005 18:39:49 -0600
+
+chrony (1.20-8) unstable; urgency=high
+
+  * Added test for /usr/bin/mail in postinst.
+    Closes: #307061: Install failure: Cannot configure on system without mailx
+    I consider this bug serious because it can cause installation to fail
+    and so I want to get the fix into Sarge.
+
+  * Fixed typo in chrony.conf, replaced '/etc/init.d/chrony restart'
+    with 'invoke-rc.d chrony restart'.
+    Closes: #305090: Typo in chrony.conf, should mention invoke-rc.d
+
+  * Added README.Debian explaining that rtc is off by default.
+
+ -- John Hasler <jhasler@debian.org>  Sat, 30 Apr 2005 18:47:30 -0500
+
+chrony (1.20-7) unstable; urgency=low
+
+  * Added info-4 to debian/rules.
+    Closes: #287142: chrony: Can't find chrony.info-4
+
+  * Corrected "See Also" section in chrony man page.  Now mentions
+    chronyc(1), chronyd(8), and chrony.conf(5).
+    Closes: #287444: chrony.1.gz: SEE ALSO on man page has wrong section.
+
+  * Edited chrony.conf to disable rtc by default and explain why:
+    on some systems that use genrtc or the HPET real-time clock it
+    fails and causes chronyd to fill up the log.  The failure is
+    probably due to a kernel bug, bug the logging should be
+    throttled.
+
+  * Added more explanatory comments at the servers directive in
+    chrony.conf.
+
+  * The postinst script now sends a message to root saying where the
+    password is, whether Chrony is assuming UTC or local time,
+    that rtc updating is disabled, why, and how to change it.
+
+  * Added missing '#' to
+    "Can't tell how your clock is set: assuming local time."
+    in postinst.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 12 Apr 2005 17:59:13 -0500
+
+chrony (1.20-6) unstable; urgency=low
+
+  * Fixed error in chrony.conf where the non-existent 'online' directive
+    was mentioned.
+    Closes: #257235 misleading instructions in chrony.conf
+
+  * Patched Makefile.in to generate faq.html.
+    Closes: #265936 /usr/share/doc/chrony/faq.txt.gz: how to read?
+
+ -- John Hasler <jhasler@debian.org>  Sat,  4 Dec 2004 17:47:31 -0600
+
+chrony (1.20-5) unstable; urgency=low
+
+  * Put pool.ntp.org servers in chrony.conf as defaults.
+
+  * Fixed erroneous references to chronyd(1) in some man pages.
+    Closes: #241746 SEE ALSO chronyd(1) should be (8)
+
+  * I got a new motherboard and can no longer reproduce this.
+    If you can please reopen the bug.
+    Closes: #223518 Rtc stuff is broken
+
+  * Edited chrony.conf(5).
+    Closes:  #241745 many more features have been added
+
+  * Edited chrony.conf to add logchange and mailonchange and to
+    enable rtc by default.
+    Closes: #226644 /etc/chrony/chrony.conf: rtc; not all options are noted in conf file
+
+  * Fixed upstream: see NEWS.
+    Closes: #124089 mistake in the chrony manual
+    Closes: #177366: trailing blank on log lines
+    Closes: #195618 failure to use /dev/misc/rtc floods logfiles
+    Closes: #53066 "acquisitionport" directive and doc fixes [patch]
+    Closes: #100880 RFE: don't use /proc when uname(2) will do
+    Closes: #163470: different bindaddresses for ntp port and control port
+    Closes: #200174: Chrony breaks under Kernel 2.5 (two bugs)
+
+ -- John Hasler <jhasler@debian.org>  Sat, 10 Apr 2004 22:00:00 -0500
+
+chrony (1.20-4) unstable; urgency=low
+
+  * Added '#include <asm/types>' to rtc_linux.c to fix Alpha build problem.
+    Also removed spinlock stuff from configure.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 26 Dec 2003 21:00:00 -0600
+
+chrony (1.20-3) unstable; urgency=low
+
+  * Removed all inclusions of kernel headers.
+    Hopefully Chrony will now build on m68k.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 23 Dec 2003 19:00:00 -0600
+
+chrony (1.20-2) unstable; urgency=low
+
+  * Removed spinlock.h and mc146818.h from rtc_linux.c.  linux/rtc.h and
+    RTC_UIE=0x10 provide everything needed now.
+    Closes: #223134 FTBFS: Errors in kernel headers
+
+  * However, rtc is now broken (and appears to have been broken for some time)
+    on 440BX chipsets with 2.4 kernels.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 12 Dec 2003 13:00:00 -0600
+
+chrony (1.20-1) unstable; urgency=low
+
+  * New upstream release.
+
+  * Frank Otto's patch to sys_linux.c, function guess_hz_and_shift_hz now
+    incorporated upstream.
+    Closes: #198557 Fatal error: chronyd can't determine hz for kernel with HZ=200
+
+  * Security and 64 bit patches are now incorporated upstream
+    along with most non-i386 architecture patches.
+
+  * Put correct links in /usr/share/doc/chrony/timeservers.
+    Closes: #189686 /usr/share/doc/timeservers links are broken
+
+  * Put correct links in chrony.conf.
+    Closes: #210886 bad link in chrony.conf
+
+  * Put missing newlines in apm and chrony.keys.
+    Closes: #211604 Build-warning: some files misses final newline
+
+  * Removed conflict with ntpdate.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 7 Oct 2003 22:00:00 -0500
+
+chrony (1.19-10) unstable; urgency=low
+
+  * Put linux/linkage.h ahead of linux/spinlock.h as I meant to in
+    the first place.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 13 Jul 2003 7:00:00 -0500
+
+chrony (1.19-9) unstable; urgency=low
+
+  * Added "#include <linux/linkage.h>" to rtc_linux.c to fix mips
+    build failure.
+    Closes: #200165 chrony doesn't build on mips and mipsel
+
+ -- John Hasler <john@dhh.gt.org>  Sat, 12 Jul 2003 10:00:00 -0500
+
+chrony (1.19-8) unstable; urgency=low
+
+  * Added bison to build-depends because of addition of getdate.y
+
+ -- John Hasler <john@dhh.gt.org>  Tue, 3 Jun 2003 10:00:00 -0500
+
+chrony (1.19-7) unstable; urgency=high
+
+  * Closes: #186498 chronyc hangs if no chronyd is running
+    Added test for running daemon to ip-{up|down} scripts.
+    Disabled trimrtc for ALPHA
+    Closes: #195615 GPL violation - generated file without source
+  * Added a copy of getdate.y to source.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 1 Jun 2003 7:00:00 -0500
+
+chrony (1.19-6) unstable; urgency=low
+
+  * Closes: #179842 "CROAK" redefined
+    Added '#undef CROAK' before CROAK redefiniton in pktlength.h,
+    added '-DALPHA' to 'alpha' condition in configure, added
+    'ifdef ALPHA' around CROAK redefinition.
+  * Replaced many signed and unsigned longs as well as some ints,
+    shorts, and chars with stdint.h types in candm.h, md5.h, ntp.h,
+    clientlog.h, and ntp_io.c.  This should fix all 64-bit problems.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 14 Mar 2003 19:00:00 -0600
+
+chrony (1.19-5) unstable; urgency=high
+
+  * Closes: #184065 Assertion `sizeof(NTP_int32) == 4' failed on alpha
+    Fixed several spots where the author assumed that a long is 32 bits.
+    There are many more misuses of long as well as several of short and
+    char but I think I got the only ones likely to cause trouble.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 14 Mar 2003 11:00:00 -0600
+
+chrony (1.19-4) unstable; urgency=low
+
+  * Closes: #179538 FTBFS: missing build-depends on makeinfo
+    Added texinfo to build-depends.
+  * CLoses: #179508: chrony(c|d) show wrong version numbers
+    Removed spurious version.h.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 2 Feb 2003 19:00:00 -0600
+
+chrony (1.19-3) unstable; urgency=low
+
+  * Updated author's address in copyright file.
+  * Closes:  #163446 patch, that scripts can handle all commandkeys
+    Applied debugged patch.
+  * Closes: #107863 doesn't know about APM
+    Put apm script in debian/ and added rules to copy it to
+    etc/apm/event.d as instructed by the apmd maintainer.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 31 Jan 2003 18:00:00 -0600
+
+chrony (1.19-2) unstable; urgency=low
+
+  * Closes: #100879 unnecessary dependency on libm
+    Applied patch from Zack Weinberg <zack@codesourcery.com>
+  * Closes: #124091 the force-reload command of /etc/init.d/chrony should
+    use the -r option.
+    Added -r option.
+
+ -- John Hasler <john@dhh.gt.org>  Wed, 29 Jan 2003 10:00:00 -0600
+
+chrony (1.19-1) unstable; urgency=low
+
+  * New upstream release.
+  * Closes: #178338 New upstream version fixes crashes caused by adjtimex
+    failure
+  * Closes: #178101 /etc/ppp/ip-{up,down}.d/chrony installed with
+    incorrect permissions
+    This bug was previously reported and fixed in 18-1
+  * Closes: #176130 got an error when I use ppp_on_boot
+    Changed 'update-rc.d chrony defaults 83' to
+    'update-rc.d chrony defaults 14' in init.d so that chrony
+    will come up before ppp.
+  * Added code to postinst to read /etc/default/rcS and
+    set rtconutc appropriately in chrony.conf.
+  * Rewrote password generator in postinst.
+  * Closes: #100879 unnecessary dependency on libm
+    I don't know why this wasn't closed months ago.
+  * Closes: #103447 typo in "/etc/init.d/chrony"
+  * Closes: #124087 problems with /etc/init.d/chrony
+    Fixed script.
+  * Closes: #161350 /etc/ppp/ip-down.d/chrony cat unnecessary
+    Fixed scripts.
+  * Closes: #113840 ntp has been split - add conflicts?
+    Added ntp-simple and ntp-refclock to conflicts.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 26 Jan 2003 15:00:00 -0600
+
+chrony (1.18-2) unstable; urgency=low
+
+  * Corrects error in changelog which resulted
+    in uploads being erroneously classified as NMUs.
+  * Closes: #138142, #104774, #142670, #105344, #101039
+  * Closes: #162427, #56756, #98951, #99799, #139633
+  * Closes: #163469, #163408, #167416
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 3 Nov 2002 20:00:00 -0600
+
+chrony (1.18-1) unstable; urgency=low
+
+  * New upstream release.
+  * Closes: #138142 new upstream release
+  * Added Mark Brown's Alpha and PowerPC patch.
+  * Closes: #104774 hppa build failure
+    Applied patch.
+  * Closes: #142670 compilation errors on sparc
+    Applied patch.
+  * Closes: #105344 ip-{up, down}.d/chrony not executable
+    Fixed debian/rules.
+  * Closes: #101039 does not run on Alpha
+    Fixed by above mentioned Mark Brown patch.
+  * Closes: #162427 description should mention NTP
+    Fixed description.
+  * Closes: #56756 README.debian should caution about hwclock
+    Fixed README.debian.
+  * Closes: #98951 no chrony.keys file installed
+    Not reproducible, probable user error.
+  * Closes: #99799 logs world readable
+    Added umask 022 to log script.
+  * Closes: #139633 documentation error
+    Added rtconutc to chrony.conf.
+  * Closes: #163469 no default case in init.d script
+    Corrected typo.
+  * Closes: #163408 PIDFILE wrongly defined in ip-{up,down}
+    No chrony script uses any such variable.
+  * Closes: #167416 needs Build-Depends: libreadline4-dev
+
+ --  <john@dhh.gt.org>  Sun, 3 Nov 2002 10:00:00 -0600
+
+chrony (1.14-7) unstable; urgency=medium
+
+  * Changed rtc_linux.c to not include linux/mc146818rtc.h
+    when building for sparc, because Moshe Zadka says this
+    will allow chrony to build there.
+  * Closes: #142670
+
+ --  <jhasler@debian.org>  Wed, 17 Apr 2002 17:00:00 -0500
+
+chrony (1.14-6) unstable; urgency=low
+
+  * Changed architecture back to 'any'.
+  * Applied portability patch from LaMont Jones.
+  * Closes: #104774
+
+ --  <jhasler@debian.org>  Mon, 1 Apr 2002 21:00:00 -0600
+
+chrony (1.14-5) unstable; urgency=low
+
+  * Changed architecture from 'any' to 'i386 sparc'.
+    Neither I nor the author can test on anything but i386.  If
+    you want chrony on anything else send me a tested patch.
+  * Closes: #101039
+  * Closes: #104774
+
+ --  <john@dhh.gt.org>  Fri, 28 Dec 2001 20:10:00 -0600
+
+chrony (1.14-4) unstable; urgency=low
+
+  * Fixed bug in man pages.
+  * Closes: #95134
+
+ --  <john@dhh.gt.org>  Tue, 24 Apr 2001 20:10:00 -0500
+
+chrony (1.14-3) unstable; urgency=low
+
+  * Replaced <linux/spinlock.h> in rtc_linux.c with
+    typedef int spinlock_t as suggested by Paul Slootman.
+  * Put #define CROAK(message) assert(0) in pktlength.h
+    to fix Alpha build problem.
+  * Closes: #86991
+
+ --  <john@dhh.gt.org>  Sat, 24 Feb 2001 22:45:00 -0600
+
+chrony (1.14-2) unstable; urgency=low
+
+   * Closes: #84597
+
+ --  <john@dhh.gt.org>  Sat, 3 Feb 2001 21:25:00 -0600
+
+chrony (1.14-1) unstable; urgency=low
+
+   * New upstream release.
+   * Fixed more sprintfs.
+   * Closes: #50793, #52570, #48216, #65209, #62924, #70377, #61485, #76661
+
+ --  <john@dhh.gt.org>  Mon, 20 Nov 2000 20:25:00 -0600
+
+chrony (1.10-3) unstable; urgency=low
+
+   * Patched cron,weekly script with (corrected) patch
+     from Rene H. Larsen <renehl@post1.tele.dk>.
+   * Updated author address in copyright file.
+   * Compiled with egcs.
+   * Closes: #41885, #41551
+
+ --  <john@dhh.gt.org>  Sun, 25 July 1999 12:14:00 -0500
+
+chrony (1.10-2) unstable; urgency=low
+
+   * Patched rtc_linux.c with patch for SPARC from
+     bmc@visi.net.
+
+ --  <john@dhh.gt.org>  Mon, 17 May 1999 22:30:00 -0500
+
+chrony (1.10-1) unstable; urgency=low
+
+   * New upstream release.
+   * Upstream version number is 1.1.  Debian version
+     number is 1.10 because previous upstream number
+     was 1.02.
+
+ --  <john@dhh.gt.org>  Wed, 12 May 1999 20:30:00 -0500
+
+chrony (1.02-7) unstable; urgency=low
+
+   * Changed configure to permit building on non-Intel.
+
+ --  <john@dhh.gt.org>  Wed, 5 May 1999 18:00:00 -0500
+
+chrony (1.02-6) unstable; urgency=low
+
+   * Fixed postrm bug.
+
+ --  <john@dhh.gt.org>  Thur, 29 Apr 1999 18:00:00 -0500
+
+chrony (1.02-5) unstable; urgency=low
+
+   * Fixed bugs 34954 and 36921.
+   * Moved to priority extra.
+   * Added README.debian text about rtc.
+
+ --  <john@dhh.gt.org>  Thur, 15 Apr 1999 21:30:00 -0500
+
+chrony (1.02-4) unstable; urgency=low
+
+   * Replaced sprintf's with snprintf's.
+
+ --  <john@dhh.gt.org>  Sun,  28 Feb 1999 16:53:00 -0600
+
+chrony (1.02-3) unstable; urgency=low
+
+   * Fixed bugs in cron.weekly, ip-up.d, and ip-down.d.
+   * Bug 29981 is also fixed.
+
+ --  <john@dhh.gt.org>  Sun,  6 Dec 1998 9:53:00 -0600
+
+chrony (1.02-2) unstable; urgency=low
+
+  * Added cron.weekly.
+  * Changed ip-up.d, ip-down.d, and cron.weekly to read the
+    password from chrony.keys.
+  * Added code to postinst to generate a random password and
+    put it in chrony.keys.
+
+ --  <john@dhh.gt.org>  Thur,  3 Dec 1998 19:00:08 -0600
+
+chrony (1.02-1) unstable; urgency=low
+
+  * Initial Release.
+
+ --  <john@dhh.gt.org>  Fri,  6 Nov 1998 23:00:08 -0600
diff --git a/chrony-dnssrv@.service b/chrony-dnssrv@.service
new file mode 100644
index 0000000..86d374f
--- /dev/null
+++ b/chrony-dnssrv@.service
@@ -0,0 +1,17 @@
+[Unit]
+Description=DNS SRV lookup of %I for chrony
+After=chrony.service network-online.target
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/chrony/chrony-helper update-dnssrv-servers %I
+ProtectSystem=strict
+PrivateDevices=yes
+ProtectHome=yes
+ReadWritePaths=/run
+PrivateTmp=yes
+PrivateDevices=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
diff --git a/chrony-dnssrv@.timer b/chrony-dnssrv@.timer
new file mode 100644
index 0000000..8495e01
--- /dev/null
+++ b/chrony-dnssrv@.timer
@@ -0,0 +1,9 @@
+[Unit]
+Description=Periodic DNS SRV lookup of %I for chrony
+
+[Timer]
+OnActiveSec=0
+OnUnitInactiveSec=1h
+
+[Install]
+WantedBy=timers.target
diff --git a/chrony-helper b/chrony-helper
new file mode 100755
index 0000000..5099161
--- /dev/null
+++ b/chrony-helper
@@ -0,0 +1,264 @@
+#!/bin/bash
+# This script configures running chronyd to use NTP servers obtained from
+# DHCP and _ntp._udp DNS SRV records. Files with servers from DHCP are managed
+# externally (e.g. by a dhclient script). Files with servers from DNS SRV
+# records are updated here using the dig utility. The script can also list
+# and set static sources in the chronyd configuration file.
+#
+# Modified for Debian by Vincent Blut <vincent.debian@free.fr>.
+
+chronyc=/usr/bin/chronyc
+chrony_conf=/etc/chrony/chrony.conf
+chrony_service=chrony.service
+helper_dir=/run/chrony-helper
+added_servers_file=$helper_dir/added_servers
+
+dhclient_servers_files="/var/lib/dhcp/chrony.servers.*"
+dnssrv_servers_files="$helper_dir/dnssrv@*"
+dnssrv_timer_prefix=chrony-dnssrv@
+
+chrony_command() {
+    $chronyc -n -m "$1"
+}
+
+is_running() {
+    chrony_command "tracking" &> /dev/null
+}
+
+get_servers_files() {
+    echo "$dhclient_servers_files"
+    echo "$dnssrv_servers_files"
+}
+
+is_update_needed() {
+    for file in $(get_servers_files) $added_servers_file; do
+        [ -e "$file" ] && return 0
+    done
+    return 1
+}
+
+update_daemon() {
+    local all_servers_with_args all_servers added_servers
+
+    if ! is_running; then
+        rm -f $added_servers_file
+        return 0
+    fi
+
+    all_servers_with_args=$(cat $(get_servers_files) 2> /dev/null)
+
+    all_servers=$(
+        echo "$all_servers_with_args" |
+            while read -r server serverargs; do
+                echo "$server"
+            done | sort -u)
+    added_servers=$( (
+        cat $added_servers_file 2> /dev/null
+        echo "$all_servers_with_args" |
+            while read -r server serverargs; do
+                [ -z "$server" ] && continue
+                chrony_command "add server $server $serverargs" &> /dev/null &&
+                    echo "$server"
+            done) | sort -u)
+
+    comm -23 <(echo -n "$added_servers") <(echo -n "$all_servers") |
+        while read -r server; do
+            chrony_command "delete $server" &> /dev/null
+        done
+
+    added_servers=$(comm -12 <(echo -n "$added_servers") <(echo -n "$all_servers"))
+
+    if [ -n "$added_servers" ]; then
+        echo "$added_servers" > $added_servers_file
+    else
+        rm -f $added_servers_file
+    fi
+}
+
+get_dnssrv_servers() {
+    local name=$1 output
+
+    if ! command -v dig &> /dev/null; then
+        echo "Missing dig (DNS lookup utility)" >&2
+        return 1
+    fi
+
+    output=$(dig "$name" srv +short +ndots=2 +search 2> /dev/null) || return 0
+
+    echo "$output" | while read -r _ _ port target; do
+        server=${target%.}
+        [ -z "$server" ] && continue
+        echo "$server port $port iburst"
+    done
+}
+
+check_dnssrv_name() {
+    local name=$1
+
+    if [ -z "$name" ]; then
+        echo "No DNS SRV name specified" >&2
+        return 1
+    fi
+
+    if [ "${name:0:9}" != _ntp._udp ]; then
+        echo "DNS SRV name $name doesn't start with _ntp._udp" >&2
+        return 1
+    fi
+}
+
+update_dnssrv_servers() {
+    local name=$1
+    local srv_file=$helper_dir/dnssrv@$name servers
+
+    check_dnssrv_name "$name" || return 1
+
+    servers=$(get_dnssrv_servers "$name")
+    if [ -n "$servers" ]; then
+        echo "$servers" > "$srv_file"
+    else
+        rm -f "$srv_file"
+    fi
+}
+
+set_dnssrv_timer() {
+    local state=$1 name=$2
+    local srv_file=$helper_dir/dnssrv@$name servers
+    local timer
+
+    timer=$dnssrv_timer_prefix$(systemd-escape "$name").timer || return 1
+
+    check_dnssrv_name "$name" || return 1
+
+    if [ "$state" = enable ]; then
+        systemctl enable "$timer"
+        systemctl start "$timer"
+    elif [ "$state" = disable ]; then
+        systemctl stop "$timer"
+        systemctl disable "$timer"
+        rm -f "$srv_file"
+    fi
+}
+
+list_dnssrv_timers() {
+    systemctl --all --full -t timer list-units | grep "^$dnssrv_timer_prefix" | \
+            sed "s|^$dnssrv_timer_prefix\(.*\)\.timer.*|\1|" |
+        while read -r name; do
+            systemd-escape --unescape "$name"
+        done
+}
+
+prepare_helper_dir() {
+    mkdir -p $helper_dir
+    exec 100> $helper_dir/lock
+    if ! flock -w 20 100; then
+        echo "Failed to lock $helper_dir" >&2
+        return 1
+    fi
+}
+
+is_source_line() {
+    local pattern="^[ \t]*(server|pool|peer|refclock)[ \t]+[^ \t]+"
+    [[ "$1" =~ $pattern ]]
+}
+
+list_static_sources() {
+    while read -r line; do
+        if is_source_line "$line"; then
+            echo "$line"
+        fi
+    done < $chrony_conf
+}
+
+set_static_sources() {
+    local new_config tmp_conf
+
+    new_config=$(
+        sources=$(
+            while read -r line; do
+                is_source_line "$line" && echo "$line"
+            done)
+
+        while read -r line; do
+            if ! is_source_line "$line"; then
+                echo "$line"
+                continue
+            fi
+
+            tmp_sources=$(
+                local removed=0
+
+                echo "$sources" | while read -r line2; do
+                    if [ "$removed" -ne 0 ] || [ "$line" != "$line2" ]; then
+                        echo "$line2"
+                    else
+                        removed=1
+                    fi
+                done)
+
+            [ "$sources" == "$tmp_sources" ] && continue
+            sources=$tmp_sources
+            echo "$line"
+        done < $chrony_conf
+
+        echo "$sources"
+    )
+
+    tmp_conf=${chrony_conf}.tmp
+
+    cp -a $chrony_conf $tmp_conf &&
+        echo "$new_config" > $tmp_conf &&
+        mv $tmp_conf $chrony_conf || return 1
+
+    systemctl try-restart $chrony_service
+}
+
+print_help() {
+    echo "Usage: $0 COMMAND"
+    echo
+    echo "Commands:"
+    echo "	update-daemon"
+    echo "	update-dnssrv-servers NAME"
+    echo "	enable-dnssrv NAME"
+    echo "	disable-dnssrv NAME"
+    echo "	list-dnssrv"
+    echo "	list-static-sources"
+    echo "	set-static-sources < sources.list"
+    echo "	is-running"
+    echo "	command CHRONYC-COMMAND"
+}
+
+case "$1" in
+    update-daemon|add-dhclient-servers|remove-dhclient-servers)
+        is_update_needed || exit 0
+        prepare_helper_dir && update_daemon
+        ;;
+    update-dnssrv-servers)
+        prepare_helper_dir && update_dnssrv_servers "$2" && update_daemon
+        ;;
+    enable-dnssrv)
+        set_dnssrv_timer enable "$2"
+        ;;
+    disable-dnssrv)
+        set_dnssrv_timer disable "$2" && prepare_helper_dir && update_daemon
+        ;;
+    list-dnssrv)
+        list_dnssrv_timers
+        ;;
+    list-static-sources)
+        list_static_sources
+        ;;
+    set-static-sources)
+        set_static_sources
+        ;;
+    is-running)
+        is_running
+        ;;
+    command|forced-command)
+        chrony_command "$2"
+        ;;
+    *)
+        print_help
+        exit 2
+esac
+
+exit $?
diff --git a/chrony.conf b/chrony.conf
new file mode 100644
index 0000000..b3a9510
--- /dev/null
+++ b/chrony.conf
@@ -0,0 +1,47 @@
+# Welcome to the chrony configuration file. See chrony.conf(5) for more
+# information about usable directives.
+
+# Include configuration files found in /etc/chrony/conf.d.
+confdir /etc/chrony/conf.d
+
+# Use Debian vendor zone.
+pool 2.debian.pool.ntp.org iburst
+
+# Use time sources from DHCP.
+sourcedir /run/chrony-dhcp
+
+# Use NTP sources found in /etc/chrony/sources.d.
+sourcedir /etc/chrony/sources.d
+
+# This directive specify the location of the file containing ID/key pairs for
+# NTP authentication.
+keyfile /etc/chrony/chrony.keys
+
+# This directive specify the file into which chronyd will store the rate
+# information.
+driftfile /var/lib/chrony/chrony.drift
+
+# Save NTS keys and cookies.
+ntsdumpdir /var/lib/chrony
+
+# Uncomment the following line to turn logging on.
+#log tracking measurements statistics
+
+# Log files location.
+logdir /var/log/chrony
+
+# Stop bad estimates upsetting machine clock.
+maxupdateskew 100.0
+
+# This directive enables kernel synchronisation (every 11 minutes) of the
+# real-time clock. Note that it can’t be used along with the 'rtcfile' directive.
+rtcsync
+
+# Step the system clock instead of slewing it if the adjustment is larger than
+# one second, but only in the first three clock updates.
+makestep 1 3
+
+# Get TAI-UTC offset and leap seconds from the system tz database.
+# This directive must be commented out when using time sources serving
+# leap-smeared time.
+leapsectz right/UTC
diff --git a/chrony.default b/chrony.default
new file mode 100644
index 0000000..028f63d
--- /dev/null
+++ b/chrony.default
@@ -0,0 +1,6 @@
+# This is a configuration file for /etc/init.d/chrony and
+# /lib/systemd/system/chrony.service; it allows you to pass various options to
+# the chrony daemon without editing the init script or service file.
+
+# Options to pass to chrony.
+DAEMON_OPTS="-F 1"
diff --git a/chrony.dhcp b/chrony.dhcp
new file mode 100644
index 0000000..f3dacd7
--- /dev/null
+++ b/chrony.dhcp
@@ -0,0 +1,27 @@
+CHRONY_SOURCEDIR=/run/chrony-dhcp
+SERVERFILE=$CHRONY_SOURCEDIR/$interface.sources
+
+chrony_config() {
+    rm -f "$SERVERFILE"
+    mkdir -p "$CHRONY_SOURCEDIR"
+    for server in $new_ntp_servers; do
+        echo "server $server iburst" >> "$SERVERFILE"
+    done
+    /usr/bin/chronyc reload sources > /dev/null 2>&1 || :
+}
+
+chrony_restore() {
+    if [ -f "$SERVERFILE" ]; then
+        rm -f "$SERVERFILE"
+        /usr/bin/chronyc reload sources > /dev/null 2>&1 || :
+    fi
+}
+
+case $reason in
+    BOUND|RENEW|REBIND|REBOOT)
+        chrony_config
+        ;;
+    EXPIRE|FAIL|RELEASE|STOP)
+        chrony_restore
+        ;;
+esac
diff --git a/chrony.examples b/chrony.examples
new file mode 100644
index 0000000..1a0e8e2
--- /dev/null
+++ b/chrony.examples
@@ -0,0 +1 @@
+examples/chrony.conf*
diff --git a/chrony.if-post-down b/chrony.if-post-down
new file mode 100644
index 0000000..4cc0796
--- /dev/null
+++ b/chrony.if-post-down
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -e
+
+[ -x /usr/sbin/chronyd ] || exit 0
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.if-up b/chrony.if-up
new file mode 100644
index 0000000..4cc0796
--- /dev/null
+++ b/chrony.if-up
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -e
+
+[ -x /usr/sbin/chronyd ] || exit 0
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.keys b/chrony.keys
new file mode 100644
index 0000000..a2d655d
--- /dev/null
+++ b/chrony.keys
@@ -0,0 +1,10 @@
+# This file is solely used for NTP authentication with symmetric keys
+# as defined by RFC 1305 and RFC 5905.
+#
+# It can contain ID/key pairs which can be generated using the “keygen” option
+# from “chronyc”; for example:
+# chronyc keygen 1 SHA256 256 >> /etc/chrony/chrony.keys
+# would generate a 256-bit SHA-256 key using ID 1.
+#
+# A list of supported hash functions and output encoding is available by
+# consulting the "keyfile" directive in the chrony.conf(5) man page.
diff --git a/chrony.lintian-overrides b/chrony.lintian-overrides
new file mode 100644
index 0000000..83260a6
--- /dev/null
+++ b/chrony.lintian-overrides
@@ -0,0 +1,7 @@
+# The “chrony.keys” file must not be world readable as it could contain
+# symmetric keys used for NTP authentication.
+chrony: non-standard-file-perm 0640 != 0644 [usr/share/chrony/chrony.keys]
+
+# NetworkManager does not execute dispatcher scripts in /usr/libexec.
+chrony: executable-in-usr-lib [usr/lib/NetworkManager/dispatcher.d/20-chrony-dhcp]
+chrony: executable-in-usr-lib [usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline]
diff --git a/chrony.maintscript b/chrony.maintscript
new file mode 100644
index 0000000..740a898
--- /dev/null
+++ b/chrony.maintscript
@@ -0,0 +1 @@
+rm_conffile /etc/NetworkManager/dispatcher.d/20-chrony 3.5-7~ chrony
diff --git a/chrony.ppp.ip-down b/chrony.ppp.ip-down
new file mode 100644
index 0000000..c077551
--- /dev/null
+++ b/chrony.ppp.ip-down
@@ -0,0 +1,13 @@
+#!/bin/sh
+# This script tells chronyd that the connection is down
+# so that it won't try to contact the server. 
+# John Hasler <jhasler@debian.org>  1998-2003
+# Any possessor of a copy of this program may treat it as if it
+# were in the public domain.  I waive all rights.
+# Modified by Vincent Blut <vincent.debian@free.fr>
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.ppp.ip-up b/chrony.ppp.ip-up
new file mode 100644
index 0000000..9c8d089
--- /dev/null
+++ b/chrony.ppp.ip-up
@@ -0,0 +1,12 @@
+#!/bin/sh
+# This script tells chronyd that the connection is up so that it can
+# contact the server.  John Hasler <jhasler@debian.org> 1998-2003
+# Any possessor of a copy of this program may treat it as if it
+# were in the public domain.  I waive all rights.
+# Modified by Vincent Blut <vincent.debian@free.fr>
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.service b/chrony.service
new file mode 100644
index 0000000..50d08fa
--- /dev/null
+++ b/chrony.service
@@ -0,0 +1,65 @@
+[Unit]
+Description=chrony, an NTP client/server
+Documentation=man:chronyd(8) man:chronyc(1) man:chrony.conf(5)
+Conflicts=openntpd.service ntp.service ntpsec.service
+Wants=time-sync.target
+Before=time-sync.target
+After=network.target
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/default/chrony
+User=_chrony
+# Daemon is started as root, but still sandboxed
+ExecStart=!/usr/sbin/chronyd $DAEMON_OPTS
+
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD CAP_SYS_ADMIN
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
+DeviceAllow=char-pps rw
+DeviceAllow=char-ptp rw
+DeviceAllow=char-rtc rw
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProcSubset=pid
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+# Used for gps refclocks
+ReadWritePaths=/run
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap
+
+ConfigurationDirectory=chrony
+RuntimeDirectory=chrony
+RuntimeDirectoryMode=0700
+# See dumpdir in chrony.conf(5)
+RuntimeDirectoryPreserve=restart
+StateDirectory=chrony
+StateDirectoryMode=0750
+LogsDirectory=chrony
+LogsDirectoryMode=0750
+
+# Adjust restrictions for /usr/sbin/sendmail (mailonchange directive)
+NoNewPrivileges=no
+ReadWritePaths=-/var/spool
+RestrictAddressFamilies=AF_NETLINK
+
+[Install]
+Alias=chronyd.service
+WantedBy=multi-user.target
diff --git a/clean b/clean
new file mode 100644
index 0000000..70f5857
--- /dev/null
+++ b/clean
@@ -0,0 +1 @@
+getdate.c
diff --git a/conf.d/README b/conf.d/README
new file mode 100644
index 0000000..de1fa8e
--- /dev/null
+++ b/conf.d/README
@@ -0,0 +1,7 @@
+Files found under the /etc/chrony/conf.d directory with the .conf suffix are
+parsed in the lexicographical order of the file names when chronyd starts up.
+This enables a fragmented configuration of chronyd.
+
+Although those files can contain any directives listed in chrony.conf(5),
+it would be wiser to add NTP sources in the /etc/chrony/sources.d
+directory. Please read /etc/chrony/sources.d/README for more information.
diff --git a/control b/control
new file mode 100644
index 0000000..c9ddd59
--- /dev/null
+++ b/control
@@ -0,0 +1,54 @@
+Source: chrony
+Section: net
+Priority: optional
+Maintainer: Vincent Blut <vincent.debian@free.fr>
+Standards-Version: 4.6.1
+Build-Depends: asciidoctor,
+               bison,
+               debhelper-compat (= 13),
+               dh-apparmor,
+               gnutls-bin <!nocheck>,
+               iproute2 [linux-any] <!nocheck>,
+               libcap-dev [linux-any],
+               libedit-dev,
+               libgnutls28-dev,
+               libseccomp-dev (>= 2.4.3-1~) [amd64 arm64 armel armhf hppa i386 mips mipsel mips64el powerpc powerpcspe ppc64 ppc64el riscv64 s390x x32],
+               nettle-dev,
+               pkg-config,
+               pps-tools [linux-any],
+               procps <!nocheck>
+Homepage: https://chrony.tuxfamily.org
+Vcs-Git: https://salsa.debian.org/debian/chrony.git -b debian/latest
+Vcs-Browser: https://salsa.debian.org/debian/chrony
+Rules-Requires-Root: no
+
+Package: chrony
+Architecture: linux-any
+Pre-Depends: ${misc:Pre-Depends}
+Depends: adduser,
+         iproute2 [linux-any],
+         tzdata,
+         ucf,
+         ${misc:Depends},
+         ${shlibs:Depends}
+Suggests: dnsutils,
+          networkd-dispatcher
+Breaks: network-manager (<< 1.20.0-1~)
+Conflicts: time-daemon
+Provides: time-daemon
+Replaces: time-daemon
+Description: Versatile implementation of the Network Time Protocol
+ It consists of a pair of programs:
+ .
+ chronyd:  This is a daemon which runs in background on the system.
+ It obtains measurements (e.g. via the network) of the system's offset
+ relative to other systems and adjusts the system time accordingly. For
+ isolated systems, the user can periodically enter the correct time by
+ hand (using 'chronyc'). In either case 'chronyd' determines the rate
+ at which the computer gains or loses time, and compensates for this.
+ Chronyd implements the NTP protocol and can act as either a client or
+ a server.
+ .
+ chronyc: This is a command-line driven control and monitoring program.
+ An administrator can use this to fine-tune various parameters within
+ the daemon, add or delete servers etc whilst the daemon is running.
diff --git a/copyright b/copyright
new file mode 100644
index 0000000..3e0fbd1
--- /dev/null
+++ b/copyright
@@ -0,0 +1,187 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Upstream-Name: chrony
+Upstream-Contact: Miroslav Lichvar <mlichvar@redhat.com>
+Source: https://download.tuxfamily.org/chrony/
+
+Files: *
+Copyright: 2009-2021, Miroslav Lichvar
+           1997-2007, Richard P. Curnow
+License: GPL-2
+
+Files: main.c
+       sys_linux.c
+Copyright: 2012-2020, Miroslav Lichvar
+           2009, John G. Hasler
+           1997-2003, Richard P. Curnow
+License: GPL-2
+
+Files: ntp_io.c
+Copyright: 2009, 2013-2016, 2018-2021, Miroslav Lichvar
+           2009, Timo Teras
+           1997-2003, Richard P. Curnow
+License: GPL-2
+
+Files: sys_macosx.?
+Copyright: 2015, 2017, 2020, Bryan Christianson
+           2001, J. Hannken-Illjes
+           1997-2001, Richard P. Curnow
+License: GPL-2
+
+Files: sys_netbsd.?
+Copyright: 2001, J. Hannken-Illjes
+           1997-2001, Richard P. Curnow
+License: GPL-2
+
+Files: debian/*
+Copyright: 2015-2022, Vincent Blut
+           2012-2014, Joachim Wiedorn
+           2000-2012, John Hasler
+License: GPL-2
+
+Files: test/simulation/test.common
+Copyright: 2013-2014, Miroslav Lichvar
+License: GPL-2+
+
+Files: privops.c
+Copyright: 2015, Bryan Christianson
+           2017, Miroslav Lichvar
+License: GPL-2
+
+Files: privops.h
+Copyright: 2015, Bryan Christianson
+License: GPL-2
+
+Files: contrib/bryan_christianson_1/chronylogrotate.sh
+Copyright: 2015, Bryan Christianson
+License: GPL-2
+
+Files: test/unit/*
+Copyright: 2016-2022, Miroslav Lichvar
+License: GPL-2
+
+Files: hwclock.?
+Copyright: 2016-2018, 2022, Miroslav Lichvar
+License: GPL-2
+
+Files: ntp_io_linux.?
+Copyright: 2016-2019, 2021-2022 Miroslav Lichvar
+License: GPL-2
+
+Files: ntp_signd.?
+Copyright: 2016, Miroslav Lichvar
+License: GPL-2
+
+Files: client.c
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Lonnie Abelbeck
+           2009-2022, Miroslav Lichvar
+License: GPL-2
+
+Files: configure
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Bryan Christianson
+           2009, 2012-2021, Miroslav Lichvar
+           2019, Stefan R. Filipek
+License: GPL-2
+
+Files: doc/chrony.conf.adoc
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Stephen Wadeley
+           2009-2022, Miroslav Lichvar
+           2017, Bryan Christianson
+License: GPL-2
+
+Files: doc/chronyc.adoc
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Stephen Wadeley
+           2009-2017, 2019-2022, Miroslav Lichvar
+License: GPL-2
+
+Files: refclock.c
+Copyright: 2009-2011, 2013-2014, 2016-2019, 2022 Miroslav Lichvar
+License: GPL-2
+
+Files: refclock_phc.c
+Copyright: 2013, 2017, Miroslav Lichvar
+License: GPL-2
+
+Files: regress.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011, 2016-2017, Miroslav Lichvar
+License: GPL-2
+
+Files: sched.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011, 2013-2016, Miroslav Lichvar
+License: GPL-2
+
+Files: sourcestats.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011-2014, 2016-2018, 2021, Miroslav Lichvar
+License: GPL-2
+
+Files: stubs.c
+Copyright: 2014-2016, Miroslav Lichvar
+License: GPL-2
+
+Files: hash_nettle.c
+Copyright: 2018, Miroslav Lichvar
+License: GPL-2
+
+Files: test/system/*
+Copyright: 2019, Miroslav Lichvar
+License: GPL-2
+
+Files: md5.*
+Copyright: 1990, RSA Data Security, Inc. All rights reserved.
+License: RSA-MD
+  License to copy and use this software is granted provided that
+  it is identified as the "RSA Data Security, Inc. MD5 Message-
+  Digest Algorithm" in all material mentioning or referencing this
+  software or this function.
+  .
+  License is also granted to make and use derivative works
+  provided that such works are identified as "derived from the RSA
+  Data Security, Inc. MD5 Message-Digest Algorithm" in all
+  material mentioning or referencing the derived work.
+  .
+  RSA Data Security, Inc. makes no representations concerning
+  either the merchantability of this software or the suitability
+  of this software for any particular purpose.  It is provided "as
+  is" without express or implied warranty of any kind.
+  .
+  These notices must be retained in any copies of any part of this
+  documentation and/or software.
+
+License: GPL-2
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License version 2 as
+  published by the Free Software Foundation.
+  .
+  This package is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  .
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+  .
+  On Debian systems, the complete text of the GNU General Public License
+  version 2 can be found in the file `/usr/share/common-licenses/GPL-2'.
+
+License: GPL-2+
+  This package is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+  .
+  This package is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  .
+  You should have received a copy of the GNU General Public License
+  along with this program. If not, see <https://www.gnu.org/licenses/>
+  .
+  On Debian systems, the complete text of the GNU General Public License
+  version 2 can be found in `/usr/share/common-licenses/GPL-2'.
diff --git a/dirs b/dirs
new file mode 100644
index 0000000..152a039
--- /dev/null
+++ b/dirs
@@ -0,0 +1,6 @@
+etc/chrony
+etc/logrotate.d
+etc/ppp/ip-down.d
+etc/ppp/ip-up.d
+usr/lib/NetworkManager/dispatcher.d
+var/lib/chrony
diff --git a/docs b/docs
new file mode 100644
index 0000000..e12f653
--- /dev/null
+++ b/docs
@@ -0,0 +1,3 @@
+FAQ
+NEWS
+README
diff --git a/init b/init
new file mode 100644
index 0000000..ce121d7
--- /dev/null
+++ b/init
@@ -0,0 +1,69 @@
+#! /bin/sh
+#
+# Written by Miquel van Smoorenburg <miquels@drinkel.ow.org>.
+# Modified for Debian GNU/Linux by Ian Murdock <imurdock@gnu.ai.mit.edu>.
+# Modified for Debian by Christoph Lameter <clameter@debian.org>
+# Modified for chrony by John Hasler <jhasler@debian.org> 1998-2012
+# Modified for Debian by Vincent Blut <vincent.debian@free.fr>
+
+### BEGIN INIT INFO
+# Provides:          chrony
+# Required-Start:    $remote_fs
+# Required-Stop:     $remote_fs
+# Should-Start:      $syslog $network $named $time
+# Should-Stop:       $syslog $network $named $time
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: Controls chronyd NTP time daemon
+# Description:       Chronyd is the NTP time daemon in the Chrony package
+### END INIT INFO
+
+PATH=/bin:/usr/bin:/sbin:/usr/sbin
+DAEMON=/usr/sbin/chronyd
+NAME="chronyd"
+DESC="time daemon"
+PIDFILE=/run/chrony/chronyd.pid
+
+[ -x "$DAEMON" ] || exit 0
+
+. /lib/lsb/init-functions
+
+# Override this variable by editing /etc/default/chrony.
+DAEMON_OPTS=""
+if [ -f /etc/default/chrony ]; then
+    . /etc/default/chrony
+fi
+
+case "$1" in
+    start)
+        if $0 status > /dev/null ; then
+            log_success_msg "$NAME is already running"
+        else
+            log_daemon_msg "Starting $DESC" "$NAME"
+            start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON -- $DAEMON_OPTS
+            log_end_msg $?
+        fi
+        ;;
+
+    stop)
+        log_daemon_msg "Stopping $DESC" "$NAME"
+        start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE --exec $DAEMON
+        log_end_msg $?
+        ;;
+
+    restart|force-reload)
+        $0 stop
+        $0 start
+        ;;
+
+    status)
+        status_of_proc -p $PIDFILE "$DAEMON" "$NAME" && exit 0 || exit $?
+        ;;
+
+    *)
+        log_action_msg "Usage: /etc/init.d/chrony {start|stop|restart|force-reload|status}"
+        exit 1
+        ;;
+esac
+
+exit 0
diff --git a/install b/install
new file mode 100644
index 0000000..e7dc12a
--- /dev/null
+++ b/install
@@ -0,0 +1,7 @@
+debian/chrony-dnssrv@.* lib/systemd/system
+debian/chrony-helper usr/libexec/chrony
+debian/chrony.conf usr/share/chrony
+debian/conf.d etc/chrony
+debian/ntp-units.d/50-chrony.list usr/lib/systemd/ntp-units.d
+debian/sources.d etc/chrony
+debian/usr.sbin.chronyd etc/apparmor.d
diff --git a/links b/links
new file mode 100644
index 0000000..31cfb4a
--- /dev/null
+++ b/links
@@ -0,0 +1,5 @@
+# Update sources in response to systemd-networkd events (LP: #1718227).
+# This is reusing the NetworkManager dispatch script which has no hard
+# dependency to NetworkManager (not using any of its arguments)
+usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline usr/lib/networkd-dispatcher/routable.d/chrony-onoffline
+usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline usr/lib/networkd-dispatcher/off.d/chrony-onoffline
diff --git a/ntp-units.d/50-chrony.list b/ntp-units.d/50-chrony.list
new file mode 100644
index 0000000..6b9cca0
--- /dev/null
+++ b/ntp-units.d/50-chrony.list
@@ -0,0 +1 @@
+chrony.service
diff --git a/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch b/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
new file mode 100644
index 0000000..2df6629
--- /dev/null
+++ b/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
@@ -0,0 +1,19 @@
+Description: Move server_dir path to /run
+Author: Vincent Blut <vincent.debian@free.fr>
+Forwarded: no
+Last-Update: 2020-09-16
+---
+This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
+Index: chrony/examples/chrony.nm-dispatcher.dhcp
+===================================================================
+--- chrony.orig/examples/chrony.nm-dispatcher.dhcp
++++ chrony/examples/chrony.nm-dispatcher.dhcp
+@@ -10,7 +10,7 @@ action=$2
+ 
+ chronyc=/usr/bin/chronyc
+ server_options=iburst
+-server_dir=/var/run/chrony-dhcp
++server_dir=/run/chrony-dhcp
+ 
+ dhcp_server_file=$server_dir/$interface.sources
+ dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
diff --git a/patches/series b/patches/series
new file mode 100644
index 0000000..f5b7c27
--- /dev/null
+++ b/patches/series
@@ -0,0 +1 @@
+nm-dispatcher-dhcp_Move-server_dir-to-run.patch
diff --git a/postinst b/postinst
new file mode 100644
index 0000000..0d7fc06
--- /dev/null
+++ b/postinst
@@ -0,0 +1,73 @@
+#!/bin/sh
+# postinst script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+
+# targets: configure|abort-upgrade|abort-remove|abort-deconfigure
+
+case "$1" in
+    configure)
+
+        adduser --force-badname \
+                --system \
+                --group \
+                --quiet \
+                --gecos "Chrony daemon" \
+                --home /var/lib/chrony \
+                --no-create-home _chrony
+
+        if command -v ucf >/dev/null
+        then
+            ucf --three-way /usr/share/chrony/chrony.conf /etc/chrony/chrony.conf
+            ucf --three-way /usr/share/chrony/chrony.keys /etc/chrony/chrony.keys
+            if [ -x "$(command -v ucfr)" ]; then
+                ucfr chrony /etc/chrony/chrony.conf
+                ucfr chrony /etc/chrony/chrony.keys
+            fi
+        fi
+
+        # Change the user and group ownership of "/var/l{ib,og}/chrony" iif
+        # the chronyd's configuration does not contain the "user" directive.
+        # Also, update these directories' mode bits to 0750 to follow upstream.
+        if ! chronyd -p | grep -q "^user"; then
+            for d in /var/lib/chrony /var/log/chrony; do
+                if ! dpkg-statoverride --list "$d" >/dev/null; then
+                    dpkg-statoverride --update --add _chrony _chrony 0750 "$d"
+                fi
+            done
+        fi
+
+        if [ -n "$2" ] && dpkg --compare-versions "$2" lt 4.0~pre4-1; then
+            # Migrate NTP sources obtained from DHCP to /run/chrony-dhcp
+            mkdir -p /run/chrony-dhcp
+            for file in $(find /var/lib/dhcp/ -type f -name "chrony.servers.*"); do
+                sed 's/.*/server &/' < "$file" > /run/chrony-dhcp/"${file##*servers.}.sources"
+            done
+
+            # Remove the staled PID file resulting from migrating its path from
+            # /run to /run/chrony/. Overriding dh_installinit and
+            # dh_systemd_start to use the --no-restart-after-upgrade option
+            # was a possibility but chronyd would have been down even longer
+            # during the upgrade.
+            rm -f /run/chronyd.pid
+        fi
+    ;;
+
+    abort-upgrade|abort-remove|abort-deconfigure)
+    ;;
+
+    *)
+        echo "postinst called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/postrm b/postrm
new file mode 100644
index 0000000..b864a94
--- /dev/null
+++ b/postrm
@@ -0,0 +1,56 @@
+#!/bin/sh
+# postrm script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# targets: purge|remove|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear
+
+case "$1" in
+    purge)
+        rm -f /var/lib/chrony/*
+        rm -f /etc/chrony/chrony.conf
+        rm -f /etc/chrony/chrony.keys
+        if command -v ucf >/dev/null
+        then
+            ucf --purge /etc/chrony/chrony.conf
+            ucf --purge /etc/chrony/chrony.keys
+            if [ -x "$(command -v ucfr)" ]; then
+                ucfr --purge chrony /etc/chrony/chrony.conf
+                ucfr --purge chrony /etc/chrony/chrony.keys
+            fi
+        fi
+        rm -rf /etc/chrony
+        rm -rf /run/chrony || true
+        rm -rf /run/chrony-dhcp || true
+        rm -rf /var/lib/chrony
+        rm -rf /var/log/chrony
+        # Remove "_chrony" system user/group
+        if [ -x "$(command -v deluser)" ]
+        then
+            deluser --quiet --system _chrony > /dev/null 2>&1 || true
+        fi
+
+        for d in /var/lib/chrony /var/log/chrony; do
+            if dpkg-statoverride --list "$d" >/dev/null; then
+                dpkg-statoverride --remove "$d"
+            fi
+        done
+    ;;
+
+    remove|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
+    ;;
+
+    *)
+        echo "postrm called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/prerm b/prerm
new file mode 100644
index 0000000..ec12057
--- /dev/null
+++ b/prerm
@@ -0,0 +1,28 @@
+#!/bin/sh
+# prerm script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# targets: remove|upgrade|deconfigure|failed-upgrade
+
+case "$1" in
+    remove|upgrade|deconfigure)
+    ;;
+
+    failed-upgrade)
+    ;;
+
+    *)
+        echo "prerm called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/rules b/rules
new file mode 100755
index 0000000..2da974d
--- /dev/null
+++ b/rules
@@ -0,0 +1,45 @@
+#!/usr/bin/make -f
+
+-include /usr/share/dpkg/buildtools.mk
+export CC
+
+include /usr/share/dpkg/architecture.mk
+
+export DEB_BUILD_MAINT_OPTIONS=hardening=+all
+
+BASE=debian/chrony
+
+%:
+	dh $@
+
+override_dh_auto_configure:
+	dh_auto_configure --  --mandir=/usr/share/man \
+		--sysconfdir=/etc/chrony \
+		--with-user=_chrony \
+		--enable-scfilter \
+		--chronyrundir=/run/chrony \
+		--with-ntp-era=$(shell date -d '1970-01-01 00:00:00+00:00' +'%s') \
+		--enable-ntp-signd \
+		--with-hwclockfile=/etc/adjtime \
+		--with-pidfile=/run/chrony/chronyd.pid \
+		--host-system=Linux
+
+override_dh_install:
+	dh_install
+	install -m 0640 -t $(BASE)/usr/share/chrony/ debian/chrony.keys
+	install -m 0755 -T examples/chrony.nm-dispatcher.dhcp ${BASE}/usr/lib/NetworkManager/dispatcher.d/20-chrony-dhcp
+	install -m 0755 -T examples/chrony.nm-dispatcher.onoffline $(BASE)/usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline
+	install -m 0644 -T examples/chrony.logrotate $(BASE)/etc/logrotate.d/chrony
+	dh_apparmor --profile-name=usr.sbin.chronyd -pchrony
+	install -D -p -m 0644 debian/chrony.dhcp $(BASE)/etc/dhcp/dhclient-exit-hooks.d/chrony
+
+override_dh_fixperms:
+	dh_fixperms -X usr/share/chrony/chrony.keys
+
+override_dh_installinit:
+	dh_installinit
+# Disable the system call filter on architectures mentioned below
+# due to missing support in libseccomp and/or in the Linux kernel.
+ifneq (,$(filter $(DEB_HOST_ARCH), alpha ia64 m68k sh4 sparc64))
+	sed -i '/DAEMON_OPTS=/s/"-F 1"/""/' $(BASE)/etc/default/chrony
+endif
diff --git a/source/format b/source/format
new file mode 100644
index 0000000..163aaf8
--- /dev/null
+++ b/source/format
@@ -0,0 +1 @@
+3.0 (quilt)
diff --git a/sources.d/README b/sources.d/README
new file mode 100644
index 0000000..184eaec
--- /dev/null
+++ b/sources.d/README
@@ -0,0 +1,12 @@
+Only NTP sources can be specified in the /etc/chrony/sources.d directory.
+Files in this directory must end with the ".sources" suffix. They can only
+contain the "peer", "pool" and "server" directives and must have all
+lines terminated by a trailing newline.
+
+There is no need to restart chronyd for these time sources to be usable,
+running 'chronyc reload sources' is sufficient.
+
+Example:
+
+# echo 'server 192.0.2.1 iburst' > /etc/chrony/sources.d/local-ntp-server.sources
+# chronyc reload sources
diff --git a/tests/control b/tests/control
new file mode 100644
index 0000000..5586711
--- /dev/null
+++ b/tests/control
@@ -0,0 +1,28 @@
+Tests: upstream-simulation-test-suite
+Depends: @builddeps@, build-essential, ca-certificates, wget
+Restrictions: isolation-container, build-needed, skippable, needs-root, needs-internet
+
+Tests: time-sources-from-dhcp-servers
+Depends: @, isc-dhcp-server, isc-dhcp-client, iproute2, kmod
+Restrictions: isolation-machine, needs-root
+
+Features: test-name=run_system_tests
+Test-Command: debian/tests/upstream-system-tests
+Depends: @builddeps@
+Restrictions: build-needed, isolation-container, needs-root
+
+Features: test-name=run_destructive_system_tests
+Test-Command: debian/tests/upstream-system-tests -d 1[0-9][0-9]-*
+Depends: @, @builddeps@, ethtool
+Restrictions: build-needed, isolation-machine, needs-root
+
+Tests: fragmented-configuration
+Restrictions: isolation-container, needs-root
+
+Tests: dynamically-add-source
+Depends: @, dpkg-dev
+Restrictions: isolation-container, needs-root, skippable
+
+Tests: ntp-server-and-nts-auth
+Depends: @, dpkg-dev, gnutls-bin
+Restrictions: isolation-container, needs-root, skippable
diff --git a/tests/dynamically-add-source b/tests/dynamically-add-source
new file mode 100644
index 0000000..1e4c160
--- /dev/null
+++ b/tests/dynamically-add-source
@@ -0,0 +1,27 @@
+#!/bin/sh
+# Make sure that NTP sources from /etc/chrony/sources.d are usable.
+
+set -e
+
+. debian/tests/helper-functions
+
+server_addr="192.0.2.1"
+
+printf "Preparing chronyd configuration: "
+__no_system_clock_control
+__restart_chronyd && __test_ok || __test_skip
+
+printf "Adding a dummy server to the list of NTP sources: "
+printf "server $server_addr\n" > /etc/chrony/sources.d/dummy-server.sources && __test_ok || __test_fail
+
+printf "Reloading NTP sources: "
+__reload_sources
+
+printf "Checking for dummy server availability: "
+__check_sources "$server_addr"
+
+printf "Checking for dummy server availability after restarting chronyd: "
+__restart_chronyd
+__check_sources "$server_addr"
+
+exit 0
diff --git a/tests/fragmented-configuration b/tests/fragmented-configuration
new file mode 100644
index 0000000..2135df3
--- /dev/null
+++ b/tests/fragmented-configuration
@@ -0,0 +1,17 @@
+#!/bin/sh
+# Make sure that fragmented configuration works as expected.
+
+set -e
+
+. debian/tests/helper-functions
+
+printf 'Setting "authselectmode prefer" as authentication policy: '
+echo "authselectmode prefer" > /etc/chrony/conf.d/authentication-policy.conf && __test_ok || __test_fail
+
+printf "Restart chronyd: "
+systemctl --quiet restart chrony.service && __test_ok || __test_fail
+
+printf "Checking that chronyd uses the defined authentication policy: "
+chronyd -p | grep -q "authselectmode prefer" && __test_ok || __test_fail
+
+exit 0
diff --git a/tests/helper-functions b/tests/helper-functions
new file mode 100644
index 0000000..7df6ee9
--- /dev/null
+++ b/tests/helper-functions
@@ -0,0 +1,53 @@
+__no_system_clock_control() {
+    if ! dpkg-vendor --derives-from Ubuntu; then
+        sed -i '/^DAEMON_OPTS=/s/"\(.*\)"/"\1 -x"/' /etc/default/chrony
+        mkdir -p /etc/systemd/system/chrony.service.d
+        cat <<EOF > /etc/systemd/system/chrony.service.d/override.conf
+[Unit]
+ConditionCapability=
+EOF
+        systemctl daemon-reload
+    fi
+}
+
+__test_fail() {
+    printf 'FAIL\n' >&2
+    return 1
+}
+
+__test_ok() {
+    printf 'OK\n'
+    return 0
+}
+
+__test_skip() {
+    [ -n "$1" ] && printf 'SKIP: (%s)\n' "$1" || printf 'SKIP\n'
+    exit 77
+}
+
+__reload_sources() {
+    chronyc reload sources > /dev/null 2>&1 && __test_ok || __test_fail
+}
+
+__restart_chronyd() {
+    systemctl --quiet restart chrony.service
+    rc=$?
+    sleep 3
+    return $rc
+}
+
+__check_sources() {
+    chronyc sources | grep -q "$1" && __test_ok || __test_fail
+}
+
+__check_auth() {
+    chronyc -c authdata | grep -q "$1" && __test_ok || __test_fail
+}
+
+# Ubuntu's default config is fully populated causing issues with the test
+# If any of those tests run on Ubuntu, clear some and restart the daemon
+# to pick this up before entering the tests.
+if grep -q "^pool.*ubuntu.pool.ntp.org" /etc/chrony/chrony.conf; then
+    sudo sed -i -e '/^pool.*ubuntu.pool.ntp.org/d' /etc/chrony/chrony.conf
+    __restart_chronyd
+fi
diff --git a/tests/ntp-server-and-nts-auth b/tests/ntp-server-and-nts-auth
new file mode 100644
index 0000000..b7d8877
--- /dev/null
+++ b/tests/ntp-server-and-nts-auth
@@ -0,0 +1,59 @@
+#!/bin/sh
+# Check that chronyd is able to authenticate NTP packets when NTS is enabled
+# on the server.
+
+set -e
+
+. debian/tests/helper-functions
+
+cert_dir="/var/lib/chrony"
+cert_template="$cert_dir/cert.cfg"
+cert_file="$cert_dir/server.crt"
+priv_key="$cert_dir/server.key"
+server_addr="127.0.1.1"
+server_name="chrony-nts-test"
+
+create_cert_template() {
+    printf "Creating certificate template: "
+    cat <<EOF > "$cert_template"
+cn = "$server_name"
+serial = 001
+activation_date = "$(date -d '1 year ago' +'%Y-%m-%d') 00:00:00 UTC"
+expiration_date = "$(date -d '1 year' +'%Y-%m-%d') 00:00:00 UTC"
+signing_key
+encryption_key
+EOF
+}
+
+generate_cert() {
+    printf "Generating self-signed certificate: "
+    certtool --generate-privkey --key-type=ed25519 --outfile "$priv_key" > /dev/null 2>&1
+    certtool --generate-self-signed --load-privkey "$priv_key" --template "$cert_template" \
+        --outfile "$cert_file" > /dev/null 2>&1
+}
+
+server_config() {
+    printf "Preparing chronyd configuration: "
+    cat <<EOF > /etc/chrony/conf.d/local-server-config.conf
+server $server_name nts minpoll -6 maxpoll -6
+ntsserverkey $priv_key
+ntsservercert $cert_file
+ntstrustedcerts $cert_file
+EOF
+
+    __no_system_clock_control
+    __restart_chronyd
+}
+
+echo "$server_addr $server_name" >> /etc/hosts
+
+create_cert_template && __test_ok || __test_skip "unable to create certificate template"
+
+generate_cert && __test_ok || __test_skip "unable to generate self-signed certificate"
+
+server_config && __test_ok || __test_skip
+
+printf "Checking if server authenticates NTP packets: "
+__check_auth "$server_addr,NTS"
+
+exit 0
diff --git a/tests/time-sources-from-dhcp-servers b/tests/time-sources-from-dhcp-servers
new file mode 100644
index 0000000..f5e7899
--- /dev/null
+++ b/tests/time-sources-from-dhcp-servers
@@ -0,0 +1,44 @@
+#!/bin/sh
+# Ensure that NTP servers obtained from DHCP are made available to chronyd and
+# that they are removed when releasing the DHCP lease.
+
+set -e
+
+prepare_iface() {
+    modprobe dummy
+    ip link add name dummy0 type dummy
+    ip address add 192.168.1.1/24 dev dummy0
+    ip link set dev dummy0 up
+}
+
+dhcpd_config() {
+cat <<EOF > /etc/dhcp/dhcpd.conf
+default-lease-time 600;
+max-lease-time 7200;
+authorative;
+
+subnet 192.168.1.0 netmask 255.255.255.0 {
+    option subnet-mask              255.255.255.0;
+    option broadcast-address        192.168.1.255;
+    option ntp-servers              192.168.1.50;
+    range 192.168.1.42 192.168.1.100;
+}
+EOF
+
+sed -i '/INTERFACESv4=/s/".*"/"dummy0"/' /etc/default/isc-dhcp-server
+}
+
+chk_time_src() {
+    chronyc -n sources | grep -q -F '192.168.1.50'
+}
+
+printf "Preparing the dummy network interface and dhcpd configuration…\n"
+if prepare_iface && dhcpd_config; then
+    systemctl restart isc-dhcp-server && dhclient dummy0 && printf "Done!\n\n"
+fi
+
+printf "Check if the NTP server is made available to chronyd…\n"
+chk_time_src && printf "SUCCESS!\n\n"
+
+printf "Release the current lease and check if the NTP server has been correctly removed…\n"
+dhclient -r dummy0 > /dev/null 2>&1 && ! chk_time_src && printf "SUCCESS!\n\n"
diff --git a/tests/upstream-simulation-test-suite b/tests/upstream-simulation-test-suite
new file mode 100644
index 0000000..1d25f85
--- /dev/null
+++ b/tests/upstream-simulation-test-suite
@@ -0,0 +1,41 @@
+#!/bin/sh
+# Upstream makes use of “clknetsim” to test how well “chronyd” controls the
+# system clocks in various conditions. Due to “clknetsim” not being available
+# in Debian, let’s use autopkgtest facility to build it in a container and
+# test “chronyd” from there.
+
+set -e
+
+testdir="$PWD/test/simulation"
+clknetsim_ver=f00531b
+clknetsim_src=https://github.com/mlichvar/clknetsim/archive/"$clknetsim_ver"/clknetsim-"$clknetsim_ver".tar.gz
+clknetsim_archive=$(basename "$clknetsim_src")
+
+export CLKNETSIM_PATH="$AUTOPKGTEST_TMP"
+
+# Always use the same seed to get deterministic results
+export CLKNETSIM_RANDOM_SEED=24505
+
+DEB_HOST_MULTIARCH=$(dpkg-architecture -qDEB_HOST_MULTIARCH)
+
+# The simulation tests are only supported on Linux.
+dpkg-architecture -ilinux-any || exit 77
+
+prepare_clknetsim() {
+    # This symbolic link is necessary to prevent clknetsim from FTBFS.
+    ln -s /usr/include/"$DEB_HOST_MULTIARCH"/sys/time.h /usr/include/sys/
+
+    wget -P "$CLKNETSIM_PATH" "$clknetsim_src" 2>&1 || exit 77
+    tar -xvzf "$CLKNETSIM_PATH"/"$clknetsim_archive" \
+        -C "$CLKNETSIM_PATH" --strip-components=1 2>&1 || exit 77
+
+    if [ ! -x "$CLKNETSIM_PATH/clknetsim" ] && [ ! -e "$CLKNETSIM_PATH/clknetsim.so" ]; then
+        make -C "$CLKNETSIM_PATH" 2>&1
+    fi
+}
+
+run_test() {
+    cd "$testdir" && ./run -i 20 -m 2
+}
+
+prepare_clknetsim && run_test
diff --git a/tests/upstream-system-tests b/tests/upstream-system-tests
new file mode 100755
index 0000000..bd28a0c
--- /dev/null
+++ b/tests/upstream-system-tests
@@ -0,0 +1,24 @@
+#!/bin/sh
+# Run the upstream system tests in a container. Destructive tests will be run in
+# a VM as they may adjust/step the system clock, block the RTC, etc.
+# In case of failure, test’s logs will be put into the directory specified by
+# the $AUTOPKGTEST_ARTIFACTS environment variable.
+
+set -e
+
+testdir=$PWD/test/system
+logdir="$testdir/tmp/*"
+
+# some tests need chrony installed, but make sure to avoid the test daemon is
+# fighting with the systems chrony service over the clock
+systemctl stop chrony.service 2>/dev/null || true
+
+run_test() {
+     cd "$testdir" && ./run "$@"
+}
+
+artifacts() {
+    cp $logdir "$AUTOPKGTEST_ARTIFACTS" && exit 1
+}
+
+run_test "$@" || artifacts
diff --git a/upstream/metadata b/upstream/metadata
new file mode 100644
index 0000000..937fa97
--- /dev/null
+++ b/upstream/metadata
@@ -0,0 +1,8 @@
+Documentation: https://chrony.tuxfamily.org/documentation.html
+Changelog: https://chrony.tuxfamily.org/news.html
+FAQ: https://chrony.tuxfamily.org/faq.html
+Contact: chrony-users@chrony.tuxfamily.org
+Security-Contact: Miroslav Lichvar <mlichvar@redhat.com>
+Bug-Submit: chrony-users@chrony.tuxfamily.org
+Repository: https://git.tuxfamily.org/chrony/chrony.git
+Repository-Browse: https://git.tuxfamily.org/chrony/chrony.git/
diff --git a/upstream/signing-key.asc b/upstream/signing-key.asc
new file mode 100644
index 0000000..e12834f
--- /dev/null
+++ b/upstream/signing-key.asc
@@ -0,0 +1,52 @@
+-----BEGIN PGP PUBLIC KEY BLOCK-----
+
+mQINBGCc9dwBEADLydyZIqgarshQeCtIlWAgP3coy0mdJwxet1CvXwF1xpq18Qi1
+Tt9RZL64SkbQ8sKryBqnPjKZdOfVT5FwUucjp9L+/j7Bhk0tqv30EIQ57rnDLJ9T
+c4LG1leO+Tc5Ym/0tvv4uMjkxr4KAKHPYrweHk6EAw06bbJ02mfy9xhlITSfyyFl
+QRoRTEjy8N2IDutA4QzbZm0T5kvI7k7s/ILG5vyNo53X5PI/rWrSqmPZ5qs0lvDv
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+W23ALtrl30a0MaWqnDo=
+=kLnA
+-----END PGP PUBLIC KEY BLOCK-----
diff --git a/usr.sbin.chronyd b/usr.sbin.chronyd
new file mode 100644
index 0000000..330e8af
--- /dev/null
+++ b/usr.sbin.chronyd
@@ -0,0 +1,85 @@
+# vim:syntax=apparmor
+# Last Modified: Sun Sep 05 16:48:05 2021
+
+abi <abi/3.0>,
+
+#include <tunables/global>
+
+/usr/sbin/chronyd flags=(attach_disconnected) {
+  #include <abstractions/base>
+  #include <abstractions/nameservice>
+
+  # For /run/chrony to be created
+  capability chown,
+
+  # Give “root” the ability to read and write the PID file
+  capability dac_override,
+  capability dac_read_search,
+
+  # Needed to support HW timestamping
+  capability net_admin,
+
+  # Needed to allow NTP server sockets to be bound to a privileged port
+  capability net_bind_service,
+
+  # Needed to allow an NTP socket to be bound to a device using the
+  # SO_BINDTODEVICE socket option on kernels before 5.7
+  capability net_raw,
+
+  # Needed to drop privileges
+  capability setgid,
+  capability setuid,
+
+  # Needed to set the SCHED_FIFO real-time scheduler at the specified priority
+  # using the '-P' option
+  capability sys_nice,
+
+  # Needed to lock chronyd into RAM
+  capability sys_resource,
+
+  # Needed to set the system/real-time clock
+  capability sys_time,
+
+  /usr/sbin/chronyd mr,
+
+  /etc/chrony/{,**} r,
+  /var/lib/chrony/{,*} rw,
+  /var/log/chrony/{,*} rw,
+  @{run}/chrony/{,*} rw,
+  @{run}/chrony-dhcp/{,*} r,
+
+  # Using the “tempcomp” directive gives chronyd the ability to improve
+  # the stability and accuracy of the clock by compensating the temperature
+  # changes measured by a sensor close to the oscillator.
+  @{sys}/class/hwmon/hwmon[0-9]*/temp[0-9]*_input r,
+  @{sys}/devices/virtual/thermal/thermal_zone[0-9]*/hwmon[0-9]*/temp[0-9]*_input r,
+
+  # Support all paths suggested in the man page (LP: #1771028). Assume these
+  # are common use cases; others should be set as local include (see below).
+  # Configs using a 'chrony.' prefix like the tempcomp config file example
+  /etc/chrony.* r,
+  # Example gpsd socket is outside @{run}/chrony/
+  @{run}/chrony.tty{,*}.sock rw,
+  # To sign replies to MS-SNTP clients by the smbd daemon
+  /var/lib/samba/ntp_signd/socket rw,
+
+  # rtc
+  /etc/adjtime r,
+  /dev/rtc{,[0-9]*} rw,
+
+  # gps devices
+  /dev/pps[0-9]* rw,
+  /dev/ptp[0-9]* rw,
+
+  # Allow reading the chronyd configuration file that timemaster(8) generates
+  @{run}/timemaster/chrony.conf r,
+
+  # For use with clocks that report via shared memory (e.g. gpsd),
+  # you may need to give ntpd access to all of shared memory, though
+  # this can be considered dangerous. See https://launchpad.net/bugs/722815
+  # for details. To enable, add this to local/usr.sbin.chronyd:
+  #     capability ipc_owner,
+
+  # Site-specific additions and overrides. See local/README for details.
+  #include <local/usr.sbin.chronyd>
+}
diff --git a/watch b/watch
new file mode 100644
index 0000000..7fc35e4
--- /dev/null
+++ b/watch
@@ -0,0 +1,3 @@
+version=4
+opts="pgpsigurlmangle=s/\.tar\.gz$/-tar-gz-asc.txt/,uversionmangle=s/-pre/~pre/" \
+https://download.tuxfamily.org/@PACKAGE@/@PACKAGE@@ANY_VERSION@@ARCHIVE_EXT@
-- 
cgit v1.2.3


From 4e19ba1a17a711b4b38180b0f3b4920a34523b52 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 31 Aug 2022 13:32:14 +0200
Subject: Import chrony_4.3.orig.tar.gz

[dgit import orig chrony_4.3.orig.tar.gz]
---
 COPYING                                            |  339 ++
 FAQ                                                | 1045 +++++
 INSTALL                                            |  165 +
 Makefile.in                                        |  139 +
 NEWS                                               |  977 ++++
 README                                             |  160 +
 addressing.h                                       |   67 +
 addrfilt.c                                         |  405 ++
 addrfilt.h                                         |   80 +
 array.c                                            |  130 +
 array.h                                            |   56 +
 candm.h                                            |  824 ++++
 client.c                                           | 3451 ++++++++++++++
 clientlog.c                                        | 1088 +++++
 clientlog.h                                        |   63 +
 cmac.h                                             |   48 +
 cmac_gnutls.c                                      |  189 +
 cmac_nettle.c                                      |  117 +
 cmdmon.c                                           | 1814 ++++++++
 cmdmon.h                                           |   40 +
 cmdparse.c                                         |  398 ++
 cmdparse.h                                         |   57 +
 conf.c                                             | 2607 +++++++++++
 conf.h                                             |  170 +
 configure                                          | 1134 +++++
 contrib/andrew_bishop_1                            |  114 +
 contrib/andrew_bishop_2                            |   95 +
 contrib/bryan_christianson_1/README.txt            |  103 +
 contrib/bryan_christianson_1/chronylogrotate.sh    |   58 +
 .../org.tuxfamily.chronyc.plist                    |   22 +
 .../org.tuxfamily.chronyd.plist                    |   19 +
 contrib/erik_bryer_1                               |   65 +
 contrib/ken_gillett_1                              |  100 +
 contrib/stephan_boettcher_1                        |  162 +
 contrib/wolfgang_weisselberg1                      |  118 +
 doc/Makefile.in                                    |   76 +
 doc/chrony.conf.adoc                               | 3071 ++++++++++++
 doc/chrony.conf.man.in                             | 4894 ++++++++++++++++++++
 doc/chronyc.adoc                                   | 1508 ++++++
 doc/chronyc.man.in                                 | 2672 +++++++++++
 doc/chronyd.adoc                                   |  222 +
 doc/chronyd.man.in                                 |  264 ++
 doc/faq.adoc                                       | 1049 +++++
 doc/installation.adoc                              |  200 +
 examples/chrony-wait.service                       |   47 +
 examples/chrony.conf.example1                      |   12 +
 examples/chrony.conf.example2                      |   47 +
 examples/chrony.conf.example3                      |  334 ++
 examples/chrony.keys.example                       |   13 +
 examples/chrony.logrotate                          |    8 +
 examples/chrony.nm-dispatcher.dhcp                 |   49 +
 examples/chrony.nm-dispatcher.onoffline            |   27 +
 examples/chronyd.service                           |   49 +
 getdate.c                                          | 2606 +++++++++++
 getdate.h                                          |   28 +
 getdate.y                                          | 1044 +++++
 hash.h                                             |   57 +
 hash_gnutls.c                                      |  145 +
 hash_intmd5.c                                      |   71 +
 hash_nettle.c                                      |  124 +
 hash_nss.c                                         |  114 +
 hash_tomcrypt.c                                    |  126 +
 hwclock.c                                          |  334 ++
 hwclock.h                                          |   54 +
 keys.c                                             |  436 ++
 keys.h                                             |   47 +
 local.c                                            |  781 ++++
 local.h                                            |  229 +
 localp.h                                           |   74 +
 logging.c                                          |  352 ++
 logging.h                                          |  129 +
 main.c                                             |  694 +++
 main.h                                             |   35 +
 manual.c                                           |  332 ++
 manual.h                                           |   46 +
 md5.c                                              |  322 ++
 md5.h                                              |   56 +
 memory.c                                           |   93 +
 memory.h                                           |   45 +
 nameserv.c                                         |  166 +
 nameserv.h                                         |   52 +
 nameserv_async.c                                   |  130 +
 nameserv_async.h                                   |   40 +
 ntp.h                                              |  182 +
 ntp_auth.c                                         |  386 ++
 ntp_auth.h                                         |   84 +
 ntp_core.c                                         | 2999 ++++++++++++
 ntp_core.h                                         |  144 +
 ntp_ext.c                                          |  192 +
 ntp_ext.h                                          |   43 +
 ntp_io.c                                           |  610 +++
 ntp_io.h                                           |   70 +
 ntp_io_linux.c                                     |  847 ++++
 ntp_io_linux.h                                     |   47 +
 ntp_signd.c                                        |  341 ++
 ntp_signd.h                                        |   42 +
 ntp_sources.c                                      | 1433 ++++++
 ntp_sources.h                                      |  152 +
 nts_ke.h                                           |   81 +
 nts_ke_client.c                                    |  442 ++
 nts_ke_client.h                                    |   56 +
 nts_ke_server.c                                    |  967 ++++
 nts_ke_server.h                                    |   49 +
 nts_ke_session.c                                   |  927 ++++
 nts_ke_session.h                                   |   93 +
 nts_ntp.h                                          |   36 +
 nts_ntp_auth.c                                     |  183 +
 nts_ntp_auth.h                                     |   43 +
 nts_ntp_client.c                                   |  709 +++
 nts_ntp_client.h                                   |   51 +
 nts_ntp_server.c                                   |  283 ++
 nts_ntp_server.h                                   |   40 +
 pktlength.c                                        |  220 +
 pktlength.h                                        |   40 +
 privops.c                                          |  696 +++
 privops.h                                          |   77 +
 ptp.h                                              |   64 +
 quantiles.c                                        |  209 +
 quantiles.h                                        |   41 +
 refclock.c                                         |  862 ++++
 refclock.h                                         |   86 +
 refclock_phc.c                                     |  184 +
 refclock_pps.c                                     |  159 +
 refclock_shm.c                                     |  134 +
 refclock_sock.c                                    |  136 +
 reference.c                                        | 1437 ++++++
 reference.h                                        |  200 +
 regress.c                                          |  704 +++
 regress.h                                          |  137 +
 reports.h                                          |  206 +
 rtc.c                                              |  242 +
 rtc.h                                              |   45 +
 rtc_linux.c                                        | 1072 +++++
 rtc_linux.h                                        |   45 +
 samplefilt.c                                       |  497 ++
 samplefilt.h                                       |   51 +
 sched.c                                            |  852 ++++
 sched.h                                            |   92 +
 siv.h                                              |   70 +
 siv_gnutls.c                                       |  271 ++
 siv_nettle.c                                       |  156 +
 siv_nettle_int.c                                   |  452 ++
 smooth.c                                           |  368 ++
 smooth.h                                           |   48 +
 socket.c                                           | 1636 +++++++
 socket.h                                           |  147 +
 sources.c                                          | 1756 +++++++
 sources.h                                          |  140 +
 sourcestats.c                                      | 1040 +++++
 sourcestats.h                                      |  141 +
 srcparams.h                                        |   93 +
 stubs.c                                            |  567 +++
 sys.c                                              |  150 +
 sys.h                                              |   53 +
 sys_generic.c                                      |  449 ++
 sys_generic.h                                      |   46 +
 sys_linux.c                                        | 1007 ++++
 sys_linux.h                                        |   52 +
 sys_macosx.c                                       |  516 +++
 sys_macosx.h                                       |   40 +
 sys_netbsd.c                                       |  158 +
 sys_netbsd.h                                       |   39 +
 sys_null.c                                         |  140 +
 sys_null.h                                         |   34 +
 sys_posix.c                                        |  109 +
 sys_posix.h                                        |   36 +
 sys_solaris.c                                      |   95 +
 sys_solaris.h                                      |   38 +
 sys_timex.c                                        |  276 ++
 sys_timex.h                                        |   48 +
 sysincl.h                                          |   69 +
 tempcomp.c                                         |  176 +
 tempcomp.h                                         |   29 +
 test/compilation/001-features                      |   36 +
 test/compilation/002-scanbuild                     |   16 +
 test/compilation/003-sanitizers                    |  103 +
 test/kernel/Makefile                               |    7 +
 test/kernel/adjtime.c                              |  185 +
 test/kernel/ntpadjtime.c                           |   75 +
 test/simulation/001-defaults                       |   13 +
 test/simulation/002-largenetwork                   |   22 +
 test/simulation/003-largefreqoffset                |   19 +
 test/simulation/004-largetimeoffset                |   18 +
 test/simulation/005-externalstep                   |   46 +
 test/simulation/006-largejitter                    |   21 +
 test/simulation/007-largewander                    |   20 +
 test/simulation/008-ntpera                         |   50 +
 test/simulation/009-sourceselection                |   40 +
 test/simulation/010-multrecv                       |   17 +
 test/simulation/011-asymjitter                     |   18 +
 test/simulation/012-daemonts                       |   15 +
 test/simulation/013-nameserv                       |   15 +
 test/simulation/101-poll                           |   56 +
 test/simulation/102-iburst                         |   23 +
 test/simulation/103-initstepslew                   |   63 +
 test/simulation/104-driftfile                      |   23 +
 test/simulation/105-ntpauth                        |   96 +
 test/simulation/106-refclock                       |  143 +
 test/simulation/107-allowdeny                      |   48 +
 test/simulation/108-peer                           |   54 +
 test/simulation/109-makestep                       |   41 +
 test/simulation/110-chronyc                        |  496 ++
 test/simulation/111-knownclient                    |   17 +
 test/simulation/112-port                           |   57 +
 test/simulation/113-leapsecond                     |   61 +
 test/simulation/114-presend                        |   25 +
 test/simulation/115-cmdmontime                     |   24 +
 test/simulation/116-minsources                     |   24 +
 test/simulation/117-fallbackdrift                  |   24 +
 test/simulation/118-maxdelay                       |   42 +
 test/simulation/119-smoothtime                     |   82 +
 test/simulation/120-selectoptions                  |   89 +
 test/simulation/121-orphan                         |   26 +
 test/simulation/122-xleave                         |   91 +
 test/simulation/123-mindelay                       |   27 +
 test/simulation/124-tai                            |   45 +
 test/simulation/125-packetloss                     |   29 +
 test/simulation/126-burst                          |   45 +
 test/simulation/127-filter                         |   43 +
 test/simulation/128-nocontrol                      |   27 +
 test/simulation/129-reload                         |  109 +
 test/simulation/130-quit                           |   31 +
 test/simulation/131-maxchange                      |   20 +
 test/simulation/132-logchange                      |   21 +
 test/simulation/133-hwtimestamp                    |   60 +
 test/simulation/134-log                            |   35 +
 test/simulation/135-ratelimit                      |   18 +
 test/simulation/136-broadcast                      |   16 +
 test/simulation/137-pool                           |   49 +
 test/simulation/138-syncloop                       |   34 +
 test/simulation/139-nts                            |  312 ++
 test/simulation/140-noclientlog                    |   21 +
 test/simulation/141-copy                           |   19 +
 test/simulation/142-ptpport                        |   41 +
 test/simulation/143-manual                         |   70 +
 test/simulation/144-exp1                           |   55 +
 test/simulation/201-freqaccumulation               |   35 +
 test/simulation/202-prefer                         |   21 +
 test/simulation/README                             |   11 +
 test/simulation/run                                |   90 +
 test/simulation/test.common                        |  528 +++
 test/system/001-minimal                            |   13 +
 test/system/002-extended                           |   13 +
 test/system/003-memlock                            |   15 +
 test/system/004-priority                           |   15 +
 test/system/006-privdrop                           |   17 +
 test/system/007-cmdmon                             |  181 +
 test/system/008-confload                           |   74 +
 test/system/009-binddevice                         |   24 +
 test/system/010-nts                                |   66 +
 test/system/099-scfilter                           |   24 +
 test/system/100-clockupdate                        |   30 +
 test/system/101-rtc                                |   19 +
 test/system/102-hwtimestamp                        |   28 +
 test/system/103-refclock                           |   19 +
 test/system/104-systemdirs                         |   19 +
 test/system/199-scfilter                           |   24 +
 test/system/run                                    |   64 +
 test/system/test.common                            |  373 ++
 test/unit/Makefile.in                              |   48 +
 test/unit/addrfilt.c                               |   83 +
 test/unit/clientlog.c                              |  292 ++
 test/unit/cmac.c                                   |  109 +
 test/unit/hash.c                                   |  131 +
 test/unit/hwclock.c                                |  117 +
 test/unit/keys.c                                   |  173 +
 test/unit/ntp_auth.c                               |  289 ++
 test/unit/ntp_core.c                               |  623 +++
 test/unit/ntp_core.keys                            |    8 +
 test/unit/ntp_ext.c                                |  167 +
 test/unit/ntp_sources.c                            |  364 ++
 test/unit/nts_ke.crt                               |    8 +
 test/unit/nts_ke.key                               |   25 +
 test/unit/nts_ke_client.c                          |  144 +
 test/unit/nts_ke_server.c                          |  230 +
 test/unit/nts_ke_session.c                         |  224 +
 test/unit/nts_ntp_auth.c                           |  112 +
 test/unit/nts_ntp_client.c                         |  284 ++
 test/unit/nts_ntp_server.c                         |  176 +
 test/unit/quantiles.c                              |   68 +
 test/unit/regress.c                                |  119 +
 test/unit/samplefilt.c                             |  120 +
 test/unit/siv.c                                    |  321 ++
 test/unit/smooth.c                                 |   63 +
 test/unit/sources.c                                |  289 ++
 test/unit/test.c                                   |  181 +
 test/unit/test.h                                   |   52 +
 test/unit/util.c                                   |  744 +++
 util.c                                             | 1550 +++++++
 util.h                                             |  258 ++
 version.txt                                        |    1 +
 291 files changed, 82732 insertions(+)
 create mode 100644 COPYING
 create mode 100644 FAQ
 create mode 100644 INSTALL
 create mode 100644 Makefile.in
 create mode 100644 NEWS
 create mode 100644 README
 create mode 100644 addressing.h
 create mode 100644 addrfilt.c
 create mode 100644 addrfilt.h
 create mode 100644 array.c
 create mode 100644 array.h
 create mode 100644 candm.h
 create mode 100644 client.c
 create mode 100644 clientlog.c
 create mode 100644 clientlog.h
 create mode 100644 cmac.h
 create mode 100644 cmac_gnutls.c
 create mode 100644 cmac_nettle.c
 create mode 100644 cmdmon.c
 create mode 100644 cmdmon.h
 create mode 100644 cmdparse.c
 create mode 100644 cmdparse.h
 create mode 100644 conf.c
 create mode 100644 conf.h
 create mode 100755 configure
 create mode 100644 contrib/andrew_bishop_1
 create mode 100644 contrib/andrew_bishop_2
 create mode 100644 contrib/bryan_christianson_1/README.txt
 create mode 100755 contrib/bryan_christianson_1/chronylogrotate.sh
 create mode 100644 contrib/bryan_christianson_1/org.tuxfamily.chronyc.plist
 create mode 100644 contrib/bryan_christianson_1/org.tuxfamily.chronyd.plist
 create mode 100644 contrib/erik_bryer_1
 create mode 100644 contrib/ken_gillett_1
 create mode 100644 contrib/stephan_boettcher_1
 create mode 100644 contrib/wolfgang_weisselberg1
 create mode 100644 doc/Makefile.in
 create mode 100644 doc/chrony.conf.adoc
 create mode 100644 doc/chrony.conf.man.in
 create mode 100644 doc/chronyc.adoc
 create mode 100644 doc/chronyc.man.in
 create mode 100644 doc/chronyd.adoc
 create mode 100644 doc/chronyd.man.in
 create mode 100644 doc/faq.adoc
 create mode 100644 doc/installation.adoc
 create mode 100644 examples/chrony-wait.service
 create mode 100644 examples/chrony.conf.example1
 create mode 100644 examples/chrony.conf.example2
 create mode 100644 examples/chrony.conf.example3
 create mode 100644 examples/chrony.keys.example
 create mode 100644 examples/chrony.logrotate
 create mode 100644 examples/chrony.nm-dispatcher.dhcp
 create mode 100644 examples/chrony.nm-dispatcher.onoffline
 create mode 100644 examples/chronyd.service
 create mode 100644 getdate.c
 create mode 100644 getdate.h
 create mode 100644 getdate.y
 create mode 100644 hash.h
 create mode 100644 hash_gnutls.c
 create mode 100644 hash_intmd5.c
 create mode 100644 hash_nettle.c
 create mode 100644 hash_nss.c
 create mode 100644 hash_tomcrypt.c
 create mode 100644 hwclock.c
 create mode 100644 hwclock.h
 create mode 100644 keys.c
 create mode 100644 keys.h
 create mode 100644 local.c
 create mode 100644 local.h
 create mode 100644 localp.h
 create mode 100644 logging.c
 create mode 100644 logging.h
 create mode 100644 main.c
 create mode 100644 main.h
 create mode 100644 manual.c
 create mode 100644 manual.h
 create mode 100644 md5.c
 create mode 100644 md5.h
 create mode 100644 memory.c
 create mode 100644 memory.h
 create mode 100644 nameserv.c
 create mode 100644 nameserv.h
 create mode 100644 nameserv_async.c
 create mode 100644 nameserv_async.h
 create mode 100644 ntp.h
 create mode 100644 ntp_auth.c
 create mode 100644 ntp_auth.h
 create mode 100644 ntp_core.c
 create mode 100644 ntp_core.h
 create mode 100644 ntp_ext.c
 create mode 100644 ntp_ext.h
 create mode 100644 ntp_io.c
 create mode 100644 ntp_io.h
 create mode 100644 ntp_io_linux.c
 create mode 100644 ntp_io_linux.h
 create mode 100644 ntp_signd.c
 create mode 100644 ntp_signd.h
 create mode 100644 ntp_sources.c
 create mode 100644 ntp_sources.h
 create mode 100644 nts_ke.h
 create mode 100644 nts_ke_client.c
 create mode 100644 nts_ke_client.h
 create mode 100644 nts_ke_server.c
 create mode 100644 nts_ke_server.h
 create mode 100644 nts_ke_session.c
 create mode 100644 nts_ke_session.h
 create mode 100644 nts_ntp.h
 create mode 100644 nts_ntp_auth.c
 create mode 100644 nts_ntp_auth.h
 create mode 100644 nts_ntp_client.c
 create mode 100644 nts_ntp_client.h
 create mode 100644 nts_ntp_server.c
 create mode 100644 nts_ntp_server.h
 create mode 100644 pktlength.c
 create mode 100644 pktlength.h
 create mode 100644 privops.c
 create mode 100644 privops.h
 create mode 100644 ptp.h
 create mode 100644 quantiles.c
 create mode 100644 quantiles.h
 create mode 100644 refclock.c
 create mode 100644 refclock.h
 create mode 100644 refclock_phc.c
 create mode 100644 refclock_pps.c
 create mode 100644 refclock_shm.c
 create mode 100644 refclock_sock.c
 create mode 100644 reference.c
 create mode 100644 reference.h
 create mode 100644 regress.c
 create mode 100644 regress.h
 create mode 100644 reports.h
 create mode 100644 rtc.c
 create mode 100644 rtc.h
 create mode 100644 rtc_linux.c
 create mode 100644 rtc_linux.h
 create mode 100644 samplefilt.c
 create mode 100644 samplefilt.h
 create mode 100644 sched.c
 create mode 100644 sched.h
 create mode 100644 siv.h
 create mode 100644 siv_gnutls.c
 create mode 100644 siv_nettle.c
 create mode 100644 siv_nettle_int.c
 create mode 100644 smooth.c
 create mode 100644 smooth.h
 create mode 100644 socket.c
 create mode 100644 socket.h
 create mode 100644 sources.c
 create mode 100644 sources.h
 create mode 100644 sourcestats.c
 create mode 100644 sourcestats.h
 create mode 100644 srcparams.h
 create mode 100644 stubs.c
 create mode 100644 sys.c
 create mode 100644 sys.h
 create mode 100644 sys_generic.c
 create mode 100644 sys_generic.h
 create mode 100644 sys_linux.c
 create mode 100644 sys_linux.h
 create mode 100644 sys_macosx.c
 create mode 100644 sys_macosx.h
 create mode 100644 sys_netbsd.c
 create mode 100644 sys_netbsd.h
 create mode 100644 sys_null.c
 create mode 100644 sys_null.h
 create mode 100644 sys_posix.c
 create mode 100644 sys_posix.h
 create mode 100644 sys_solaris.c
 create mode 100644 sys_solaris.h
 create mode 100644 sys_timex.c
 create mode 100644 sys_timex.h
 create mode 100644 sysincl.h
 create mode 100644 tempcomp.c
 create mode 100644 tempcomp.h
 create mode 100755 test/compilation/001-features
 create mode 100755 test/compilation/002-scanbuild
 create mode 100755 test/compilation/003-sanitizers
 create mode 100644 test/kernel/Makefile
 create mode 100644 test/kernel/adjtime.c
 create mode 100644 test/kernel/ntpadjtime.c
 create mode 100755 test/simulation/001-defaults
 create mode 100755 test/simulation/002-largenetwork
 create mode 100755 test/simulation/003-largefreqoffset
 create mode 100755 test/simulation/004-largetimeoffset
 create mode 100755 test/simulation/005-externalstep
 create mode 100755 test/simulation/006-largejitter
 create mode 100755 test/simulation/007-largewander
 create mode 100755 test/simulation/008-ntpera
 create mode 100755 test/simulation/009-sourceselection
 create mode 100755 test/simulation/010-multrecv
 create mode 100755 test/simulation/011-asymjitter
 create mode 100755 test/simulation/012-daemonts
 create mode 100755 test/simulation/013-nameserv
 create mode 100755 test/simulation/101-poll
 create mode 100755 test/simulation/102-iburst
 create mode 100755 test/simulation/103-initstepslew
 create mode 100755 test/simulation/104-driftfile
 create mode 100755 test/simulation/105-ntpauth
 create mode 100755 test/simulation/106-refclock
 create mode 100755 test/simulation/107-allowdeny
 create mode 100755 test/simulation/108-peer
 create mode 100755 test/simulation/109-makestep
 create mode 100755 test/simulation/110-chronyc
 create mode 100755 test/simulation/111-knownclient
 create mode 100755 test/simulation/112-port
 create mode 100755 test/simulation/113-leapsecond
 create mode 100755 test/simulation/114-presend
 create mode 100755 test/simulation/115-cmdmontime
 create mode 100755 test/simulation/116-minsources
 create mode 100755 test/simulation/117-fallbackdrift
 create mode 100755 test/simulation/118-maxdelay
 create mode 100755 test/simulation/119-smoothtime
 create mode 100755 test/simulation/120-selectoptions
 create mode 100755 test/simulation/121-orphan
 create mode 100755 test/simulation/122-xleave
 create mode 100755 test/simulation/123-mindelay
 create mode 100755 test/simulation/124-tai
 create mode 100755 test/simulation/125-packetloss
 create mode 100755 test/simulation/126-burst
 create mode 100755 test/simulation/127-filter
 create mode 100755 test/simulation/128-nocontrol
 create mode 100755 test/simulation/129-reload
 create mode 100755 test/simulation/130-quit
 create mode 100755 test/simulation/131-maxchange
 create mode 100755 test/simulation/132-logchange
 create mode 100755 test/simulation/133-hwtimestamp
 create mode 100755 test/simulation/134-log
 create mode 100755 test/simulation/135-ratelimit
 create mode 100755 test/simulation/136-broadcast
 create mode 100755 test/simulation/137-pool
 create mode 100755 test/simulation/138-syncloop
 create mode 100755 test/simulation/139-nts
 create mode 100755 test/simulation/140-noclientlog
 create mode 100755 test/simulation/141-copy
 create mode 100755 test/simulation/142-ptpport
 create mode 100755 test/simulation/143-manual
 create mode 100755 test/simulation/144-exp1
 create mode 100755 test/simulation/201-freqaccumulation
 create mode 100755 test/simulation/202-prefer
 create mode 100644 test/simulation/README
 create mode 100755 test/simulation/run
 create mode 100644 test/simulation/test.common
 create mode 100755 test/system/001-minimal
 create mode 100755 test/system/002-extended
 create mode 100755 test/system/003-memlock
 create mode 100755 test/system/004-priority
 create mode 100755 test/system/006-privdrop
 create mode 100755 test/system/007-cmdmon
 create mode 100755 test/system/008-confload
 create mode 100755 test/system/009-binddevice
 create mode 100755 test/system/010-nts
 create mode 100755 test/system/099-scfilter
 create mode 100755 test/system/100-clockupdate
 create mode 100755 test/system/101-rtc
 create mode 100755 test/system/102-hwtimestamp
 create mode 100755 test/system/103-refclock
 create mode 100755 test/system/104-systemdirs
 create mode 100755 test/system/199-scfilter
 create mode 100755 test/system/run
 create mode 100644 test/system/test.common
 create mode 100644 test/unit/Makefile.in
 create mode 100644 test/unit/addrfilt.c
 create mode 100644 test/unit/clientlog.c
 create mode 100644 test/unit/cmac.c
 create mode 100644 test/unit/hash.c
 create mode 100644 test/unit/hwclock.c
 create mode 100644 test/unit/keys.c
 create mode 100644 test/unit/ntp_auth.c
 create mode 100644 test/unit/ntp_core.c
 create mode 100644 test/unit/ntp_core.keys
 create mode 100644 test/unit/ntp_ext.c
 create mode 100644 test/unit/ntp_sources.c
 create mode 100644 test/unit/nts_ke.crt
 create mode 100644 test/unit/nts_ke.key
 create mode 100644 test/unit/nts_ke_client.c
 create mode 100644 test/unit/nts_ke_server.c
 create mode 100644 test/unit/nts_ke_session.c
 create mode 100644 test/unit/nts_ntp_auth.c
 create mode 100644 test/unit/nts_ntp_client.c
 create mode 100644 test/unit/nts_ntp_server.c
 create mode 100644 test/unit/quantiles.c
 create mode 100644 test/unit/regress.c
 create mode 100644 test/unit/samplefilt.c
 create mode 100644 test/unit/siv.c
 create mode 100644 test/unit/smooth.c
 create mode 100644 test/unit/sources.c
 create mode 100644 test/unit/test.c
 create mode 100644 test/unit/test.h
 create mode 100644 test/unit/util.c
 create mode 100644 util.c
 create mode 100644 util.h
 create mode 100644 version.txt

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..d511905
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
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+
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diff --git a/FAQ b/FAQ
new file mode 100644
index 0000000..2bbb24e
--- /dev/null
+++ b/FAQ
@@ -0,0 +1,1045 @@
+Frequently Asked Questions
+
+Table of Contents
+
+  o 1. chrony compared to other programs
+      ? 1.1. How does chrony compare to ntpd?
+  o 2. Configuration issues
+      ? 2.1. What is the minimum recommended configuration for an NTP client?
+      ? 2.2. How do I make an NTP server?
+      ? 2.3. Should all computers on a LAN be clients of an external server?
+      ? 2.4. Must I specify servers by IP address if DNS is not available on
+        chronyd start?
+      ? 2.5. How can I make chronyd more secure?
+      ? 2.6. How can I make the system clock more secure?
+      ? 2.7. How can I improve the accuracy of the system clock with NTP
+        sources?
+      ? 2.8. Does chronyd have an ntpdate mode?
+      ? 2.9. Can chronyd be configured to control the clock like ntpd?
+      ? 2.10. Can NTP server be separated from NTP client?
+      ? 2.11. Should be a leap smear enabled on NTP server?
+      ? 2.12. How should chronyd be configuration with gpsd?
+      ? 2.13. Does chrony support PTP?
+      ? 2.14. Why are client log records dropped before reaching
+        clientloglimit?
+      ? 2.15. What happened to the commandkey and generatecommandkey
+        directives?
+  o 3. Computer is not synchronising
+      ? 3.1. Behind a firewall?
+      ? 3.2. Are NTP servers specified with the offline option?
+      ? 3.3. Is name resolution working correctly?
+      ? 3.4. Is chronyd allowed to step the system clock?
+      ? 3.5. Using NTS?
+      ? 3.6. Using a Windows NTP server?
+      ? 3.7. An unreachable source is selected?
+      ? 3.8. Does selected source drop new measurements?
+      ? 3.9. Using a PPS reference clock?
+  o 4. Issues with chronyc
+      ? 4.1. I keep getting the error 506 Cannot talk to daemon
+      ? 4.2. I keep getting the error 501 Not authorised
+      ? 4.3. What is the reference ID reported by the tracking command?
+      ? 4.4. Is the chronyc / chronyd protocol documented anywhere?
+  o 5. Real-time clock issues
+      ? 5.1. What is the real-time clock (RTC)?
+      ? 5.2. Does hwclock have to be disabled?
+      ? 5.3. I just keep getting the 513 RTC driver not running message
+      ? 5.4. I get Could not open /dev/rtc, Device or resource busy in my
+        syslog file
+      ? 5.5. When I start chronyd, the log says Could not enable RTC interrupt
+        : Invalid argument (or it may say disable)
+      ? 5.6. What if my computer does not have an RTC or backup battery?
+  o 6. NTP-specific issues
+      ? 6.1. Can chronyd be driven from broadcast/multicast NTP servers?
+      ? 6.2. Can chronyd transmit broadcast NTP packets?
+      ? 6.3. Can chronyd keep the system clock a fixed offset away from real
+        time?
+      ? 6.4. What happens if the network connection is dropped without using
+        chronyc's offline command first?
+      ? 6.5. Why is an offset measured between two computers synchronised to
+        each another?
+  o 7. Operation
+      ? 7.1. What clocks does chronyd use?
+  o 8. Operating systems
+      ? 8.1. Does chrony support Windows?
+      ? 8.2. Are there any plans to support Windows?
+
+1. chrony compared to other programs
+
+1.1. How does chrony compare to ntpd?
+
+chrony and ntpd are two different implementations of the Network Time Protocol
+(NTP).
+
+chrony is a newer implementation, which was designed to work well in a wider
+range of conditions. It can usually synchronise the system clock faster and
+with better time accuracy. It has many features, but it does not implement some
+of the less useful NTP modes like broadcast client or multicast server/client.
+
+If your computer is connected to the Internet only for few minutes at a time,
+the network connection is often congested, you turn your computer off or
+suspend it frequently, the clock is not very stable (e.g. there are rapid
+changes in the temperature or it is a virtual machine), or you want to use NTP
+on an isolated network with no hardware reference clocks in sight, chrony will
+probably work better for you.
+
+For a more detailed comparison of features and performance, see the comparison
+page on the chrony website.
+
+2. Configuration issues
+
+2.1. What is the minimum recommended configuration for an NTP client?
+
+First, the client needs to know which NTP servers it should ask for the current
+time. They are specified by the server or pool directive. The pool directive is
+used with names that resolve to multiple addresses of different servers. For
+reliable operation, the client should have at least three servers.
+
+The iburst option enables a burst of requests to speed up the initial
+synchronisation.
+
+To stabilise the initial synchronisation on the next start, the estimated drift
+of the system clock is saved to a file specified by the driftfile directive.
+
+If the system clock can be far from the true time after boot for any reason,
+chronyd should be allowed to correct it quickly by stepping instead of slewing,
+which would take a very long time. The makestep directive does that.
+
+In order to keep the real-time clock (RTC) close to the true time, so the
+system time is reasonably close to the true time when it is initialised on the
+next boot from the RTC, the rtcsync directive enables a mode in which the
+system time is periodically copied to the RTC. It is supported on Linux and
+macOS.
+
+If you wanted to use public NTP servers from the pool.ntp.org project, the
+minimal chrony.conf file could be:
+
+pool pool.ntp.org iburst
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+
+2.2. How do I make an NTP server?
+
+By default, chronyd does not operate as an NTP server. You need to add an allow
+directive to the chrony.conf file in order for chronyd to open the server NTP
+port and respond to client requests.
+
+allow 192.168.1.0/24
+
+An allow directive with no specified subnet allows access from all IPv4 and
+IPv6 addresses.
+
+2.3. Should all computers on a LAN be clients of an external server?
+
+It depends on the requirements. Usually, the best configuration is to make one
+computer the server, with the others as clients of it. Add a local directive to
+the server's chrony.conf file. This configuration will be better because
+
+  o the load on the external connection is less
+
+  o the load on the external NTP server(s) is less
+
+  o if your external connection goes down, the computers on the LAN will
+    maintain a common time with each other.
+
+2.4. Must I specify servers by IP address if DNS is not available on chronyd
+start?
+
+No, chronyd will keep trying to resolve the names specified by the server,
+pool, and peer directives in an increasing interval until it succeeds. The
+online command can be issued from chronyc to force chronyd to try to resolve
+the names immediately.
+
+2.5. How can I make chronyd more secure?
+
+If you do not need to use chronyc, or you want to run chronyc only under the
+root or chrony user (which can access chronyd through a Unix domain socket),
+you can disable the IPv4 and IPv6 command sockets (by default listening on
+localhost) by adding cmdport 0 to the configuration file.
+
+You can specify an unprivileged user with the -u option, or the user directive
+in the chrony.conf file, to which chronyd will switch after start in order to
+drop root privileges. The configure script has a --with-user option, which sets
+the default user. On Linux, chronyd needs to be compiled with support for the
+libcap library. On other systems, chronyd forks into two processes. The child
+process retains root privileges, but can only perform a very limited range of
+privileged system calls on behalf of the parent.
+
+Also, if chronyd is compiled with support for the Linux secure computing
+(seccomp) facility, you can enable a system call filter with the -F option. It
+will significantly reduce the kernel attack surface and possibly prevent kernel
+exploits from the chronyd process if it is compromised. It is recommended to
+enable the filter only when it is known to work on the version of the system
+where chrony is installed as the filter needs to allow also system calls made
+from libraries that chronyd is using (e.g. libc) and different versions or
+implementations of the libraries might make different system calls. If the
+filter is missing some system call, chronyd could be killed even in normal
+operation.
+
+2.6. How can I make the system clock more secure?
+
+An NTP client synchronising the system clock to an NTP server is susceptible to
+various attacks, which can break applications and network protocols relying on
+accuracy of the clock (e.g. DNSSEC, Kerberos, TLS, WireGuard).
+
+Generally, a man-in-the-middle (MITM) attacker between the client and server
+can
+
+  o make fake responses, or modify real responses from the server, to create an
+    arbitrarily large time and frequency offset, make the server appear more
+    accurate, insert a leap second, etc.
+
+  o delay the requests and/or responses to create a limited time offset and
+    temporarily also a limited frequency offset
+
+  o drop the requests or responses to prevent updates of the clock with new
+    measurements
+
+  o redirect the requests to a different server
+
+The attacks can be combined for a greater effect. The attacker can delay
+packets to create a significant frequency offset first and then drop all
+subsequent packets to let the clock quickly drift away from the true time. The
+attacker might also be able to control the server's clock.
+
+Some attacks cannot be prevented. Monitoring is needed for detection, e.g. the
+reachability register in the sources report shows missing packets. The extent
+to which the attacker can control the client's clock depends on its
+configuration.
+
+Enable authentication to prevent chronyd from accepting modified, fake, or
+redirected packets. It can be enabled with a symmetric key specified by the key
+option, or Network Time Security (NTS) by the nts option (supported since
+chrony version 4.0). The server needs to support the selected authentication
+mechanism. Symmetric keys have to be configured on both client and server, and
+each client must have its own key (one per server).
+
+The maximum offset that the attacker can insert in an NTP measurement by
+delaying packets can be limited by the maxdelay option. The default value is 3
+seconds. The measured delay is reported as the peer delay in the ntpdata report
+and measurements log. Set the maxdelay option to a value larger than the
+maximum value that is normally observed. Note that the delay can increase
+significantly even when not under an attack, e.g. when the network is congested
+or the routing has changed.
+
+The maximum accepted change in time offset between clock updates can be limited
+by the maxchange directive. Larger changes in the offset will be ignored or
+cause chronyd to exit. Note that the attacker can get around this limit by
+splitting the offset into multiple smaller offsets and/or creating a large
+frequency offset. When this directive is used, chronyd will have to be
+restarted after a successful attack. It will not be able to recover on its own.
+It must not be restarted automatically (e.g. by the service manager).
+
+The impact of a large accepted time offset can be reduced by disabling clock
+steps, i.e. by not using the makestep and initstepslew directives. The offset
+will be slowly corrected by speeding up or slowing down the clock at a rate
+which can be limited by the maxslewrate directive. Disabling clock steps
+completely is practical only if the clock cannot gain a larger error on its
+own, e.g. when the computer is shut down or suspended, and the maxslewrate
+limit is large enough to correct an expected error in an acceptable time. The
+rtcfile directive with the -s option can be used to compensate for the RTC
+drift.
+
+A more practical approach is to enable makestep for a limited number of clock
+updates (the 2nd argument of the directive) and limit the offset change in all
+updates by the maxchange directive. The attacker will be able to make only a
+limited step and only if the attack starts in a short window after booting the
+computer, or when chronyd is restarted without the -R option.
+
+The frequency offset can be limited by the maxdrift directive. The measured
+frequency offset is reported in the drift file, tracking report, and tracking
+log. Set maxdrift to a value larger than the maximum absolute value that is
+normally observed. Note that the frequency of the clock can change due to aging
+of the crystal, differences in calibration of the clock source between reboots,
+migrated virtual machine, etc. A typical computer clock has a drift smaller
+than 100 parts per million (ppm), but much larger drifts are possible (e.g. in
+some virtual machines).
+
+Use only trusted servers, which you expect to be well configured and managed,
+using authentication for their own servers, etc. Use multiple servers, ideally
+in different locations. The attacker will have to deal with a majority of the
+servers in order to pass the source selection and update the clock with a large
+offset. Use the minsources directive to increase the required number of
+selectable sources to make the selection more robust.
+
+Do not specify servers as peers. The symmetric mode is less secure than the
+client/server mode. If not authenticated, it is vulnerable to off-path
+denial-of-service attacks, and even when it is authenticated, it is still
+susceptible to replay attacks.
+
+Mixing of authenticated and unauthenticated servers should generally be
+avoided. If mixing is necessary (e.g. for a more accurate and stable
+synchronisation to a closer server which does not support authentication), the
+authenticated servers should be configured as trusted and required to not allow
+the unauthenticated servers to override the authenticated servers in the source
+selection. Since chrony version 4.0, the selection options are enabled in such
+a case automatically. This behaviour can be disabled or modified by the
+authselmode directive.
+
+An example of a client configuration limiting the impact of the attacks could
+be
+
+server foo.example.net iburst nts maxdelay 0.1
+server bar.example.net iburst nts maxdelay 0.2
+server baz.example.net iburst nts maxdelay 0.05
+server qux.example.net iburst nts maxdelay 0.1
+server quux.example.net iburst nts maxdelay 0.1
+minsources 3
+maxchange 100 0 0
+makestep 0.001 1
+maxdrift 100
+maxslewrate 100
+driftfile /var/lib/chrony/drift
+ntsdumpdir /var/lib/chrony
+rtcsync
+
+2.7. How can I improve the accuracy of the system clock with NTP sources?
+
+Select NTP servers that are well synchronised, stable and close to your
+network. It is better to use more than one server. Three or four is usually
+recommended as the minimum, so chronyd can detect servers that serve false time
+and combine measurements from multiple sources.
+
+If you have a network card with hardware timestamping supported on Linux, it
+can be enabled by the hwtimestamp directive. It should make local receive and
+transmit timestamps of NTP packets much more stable and accurate.
+
+The server directive has some useful options: minpoll, maxpoll, polltarget,
+maxdelay, maxdelayratio, maxdelaydevratio, xleave, filter.
+
+The first three options set the minimum and maximum allowed polling interval,
+and how should be the actual interval adjusted in the specified range. Their
+default values are 6 (64 seconds) for minpoll, 10 (1024 seconds) for maxpoll
+and 8 (samples) for polltarget. The default values should be used for general
+servers on the Internet. With your own NTP servers, or if you have permission
+to poll some servers more frequently, setting these options for shorter polling
+intervals might significantly improve the accuracy of the system clock.
+
+The optimal polling interval depends mainly on two factors, stability of the
+network latency and stability of the system clock (which mainly depends on the
+temperature sensitivity of the crystal oscillator and the maximum rate of the
+temperature change).
+
+Generally, if the sourcestats command usually reports a small number of samples
+retained for a source (e.g. fewer than 16), a shorter polling interval should
+be considered. If the number of samples is usually at the maximum of 64, a
+longer polling interval might work better.
+
+An example of the directive for an NTP server on the Internet that you are
+allowed to poll frequently could be
+
+server foo.example.net minpoll 4 maxpoll 6 polltarget 16
+
+An example using shorter polling intervals with a server located in the same
+LAN could be
+
+server ntp.local minpoll 2 maxpoll 4 polltarget 30
+
+The maxdelay options are useful to ignore measurements with an unusually large
+delay (e.g. due to congestion in the network) and improve the stability of the
+synchronisation. The maxdelaydevratio option could be added to the example with
+local NTP server
+
+server ntp.local minpoll 2 maxpoll 4 polltarget 30 maxdelaydevratio 2
+
+If your server supports the interleaved mode (e.g. it is running chronyd), the
+xleave option should be added to the server directive to enable the server to
+provide the client with more accurate transmit timestamps (kernel or preferably
+hardware). For example:
+
+server ntp.local minpoll 2 maxpoll 4 xleave
+
+When combined with local hardware timestamping, good network switches, and even
+shorter polling intervals, a sub-microsecond accuracy and stability of a few
+tens of nanoseconds might be possible. For example:
+
+server ntp.local minpoll 0 maxpoll 0 xleave
+hwtimestamp eth0
+
+For best stability, the CPU should be running at a constant frequency (i.e.
+disabled power saving and performance boosting). Energy-Efficient Ethernet
+(EEE) should be disabled in the network. The switches should be configured to
+prioritize NTP packets, especially if the network is expected to be heavily
+loaded. The dscp directive can be used to set the Differentiated Services Code
+Point in transmitted NTP packets if needed.
+
+If it is acceptable for NTP clients in the network to send requests at a high
+rate, a sub-second polling interval can be specified. A median filter can be
+enabled in order to update the clock at a reduced rate with more stable
+measurements. For example:
+
+server ntp.local minpoll -6 maxpoll -6 filter 15 xleave
+hwtimestamp eth0 minpoll -6
+
+Since chrony version 4.3, the minimum minpoll is -7 and a filter using a
+long-term estimate of a delay quantile can be enabled by the maxdelayquant
+option to replace the default maxdelaydevratio filter, which is sensitive to
+outliers corrupting the minimum delay. For example:
+
+server ntp.local minpoll -7 maxpoll -7 filter 31 maxdelayquant 0.3 xleave
+
+As an experimental feature added in version 4.2, chronyd supports an NTPv4
+extension field containing an additional timestamp to enable frequency transfer
+and significantly improve stability of synchronisation. It can be enabled by
+the extfield F323 option. For example:
+
+server ntp.local minpoll 0 maxpoll 0 xleave extfield F323
+
+2.8. Does chronyd have an ntpdate mode?
+
+Yes. With the -q option chronyd will set the system clock once and exit. With
+the -Q option it will print the measured offset without setting the clock. If
+you do not want to use a configuration file, NTP servers can be specified on
+the command line. For example:
+
+# chronyd -q 'pool pool.ntp.org iburst'
+
+The command above would normally take about 5 seconds if the servers were well
+synchronised and responding to all requests. If not synchronised or responding,
+it would take about 10 seconds for chronyd to give up and exit with a non-zero
+status. A faster configuration is possible. A single server can be used instead
+of four servers, the number of measurements can be reduced with the maxsamples
+option to one (supported since chrony version 4.0), and a timeout can be
+specified with the -t option. The following command would take only up to about
+one second.
+
+# chronyd -q -t 1 'server pool.ntp.org iburst maxsamples 1'
+
+It is not recommended to run chronyd with the -q option periodically (e.g. from
+a cron job) as a replacement for the daemon mode, because it performs
+significantly worse (e.g. the clock is stepped and its frequency is not
+corrected). If you must run it this way and you are using a public NTP server,
+make sure chronyd does not always start around the first second of a minute,
+e.g. by adding a random sleep before the chronyd command. Public servers
+typically receive large bursts of requests around the first second as there is
+a large number of NTP clients started from cron with no delay.
+
+2.9. Can chronyd be configured to control the clock like ntpd?
+
+It is not possible to perfectly emulate ntpd, but there are some options that
+can configure chronyd to behave more like ntpd if there is a reason to prefer
+that.
+
+In the following example the minsamples directive slows down the response to
+changes in the frequency and offset of the clock. The maxslewrate and
+corrtimeratio directives reduce the maximum frequency error due to an offset
+correction and the maxdrift directive reduces the maximum assumed frequency
+error of the clock. The makestep directive enables a step threshold and the
+maxchange directive enables a panic threshold. The maxclockerror directive
+increases the minimum dispersion rate.
+
+minsamples 32
+maxslewrate 500
+corrtimeratio 100
+maxdrift 500
+makestep 0.128 -1
+maxchange 1000 1 1
+maxclockerror 15
+
+Note that increasing minsamples might cause the offsets in the tracking and
+sourcestats reports/logs to be significantly smaller than the actual offsets
+and be unsuitable for monitoring.
+
+2.10. Can NTP server be separated from NTP client?
+
+Yes, it is possible to run multiple instances of chronyd on a computer at the
+same time. One can operate primarily as an NTP client to synchronise the system
+clock and another as a server for other computers. If they use the same
+filesystem, they need to be configured with different pidfiles, Unix domain
+command sockets, and any other file or directory specified in the configuration
+file. If they run in the same network namespace, they need to use different NTP
+and command ports, or bind the ports to different addresses or interfaces.
+
+The server instance should be started with the -x option to prevent it from
+adjusting the system clock and interfering with the client instance. It can be
+configured as a client to synchronise its NTP clock to other servers, or the
+client instance running on the same computer. In the latter case, the copy
+option (added in chrony version 4.1) can be used to assume the reference ID and
+stratum of the client instance, which enables detection of synchronisation
+loops with its own clients.
+
+On Linux, starting with chrony version 4.0, it is possible to run multiple
+server instances sharing a port to better utilise multiple cores of the CPU.
+Note that for rate limiting and client/server interleaved mode to work well it
+is necessary that all packets received from the same address are handled by the
+same server instance.
+
+An example configuration of the client instance could be
+
+pool pool.ntp.org iburst
+allow 127.0.0.1
+port 11123
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+
+and configuration of the first server instance could be
+
+server 127.0.0.1 port 11123 minpoll 0 maxpoll 0 copy
+allow
+cmdport 11323
+bindcmdaddress /var/run/chrony/chronyd-server1.sock
+pidfile /var/run/chronyd-server1.pid
+driftfile /var/lib/chrony/drift-server1
+
+2.11. Should be a leap smear enabled on NTP server?
+
+With the smoothtime and leapsecmode directives it is possible to enable a
+server leap smear in order to hide leap seconds from clients and force them to
+follow a slow server's adjustment instead.
+
+This feature should be used only in local networks and only when necessary,
+e.g. when the clients cannot be configured to handle the leap seconds as
+needed, or their number is so large that configuring them all would be
+impractical. The clients should use only one leap-smearing server, or multiple
+identically configured leap-smearing servers. Note that some clients can get
+leap seconds from other sources (e.g. with the leapsectz directive in chrony)
+and they will not work correctly with a leap smearing server.
+
+2.12. How should chronyd be configuration with gpsd?
+
+A GPS or other GNSS receiver can be used as a reference clock with gpsd. It can
+work as one or two separate time sources for each connected receiver. The first
+time source is based on timestamping of messages sent by the receiver.
+Typically, it is accurate to milliseconds. The other source is much more
+accurate. It is timestamping a pulse-per-second (PPS) signal, usually connected
+to a serial port (e.g. DCD pin) or GPIO pin.
+
+If the PPS signal is connected to the serial port which is receiving messages
+from the GPS/GNSS receiver, gpsd should detect and use it automatically. If it
+is connected to a GPIO pin, or another serial port, the PPS device needs to be
+specified on the command line as an additional data source. On Linux, the
+ldattach utility can be used to create a PPS device for a serial device.
+
+The message-based time source provided by gpsd is specified as a SHM 0
+refclock, or other even number if gpsd is configured with multiple receivers.
+
+The PPS-based time source is specified as a SHM 1 refclock (or other odd
+number), or SOCK /var/run/chrony.DEV.sock where DEV is the name of the serial
+device (e.g. ttyS0).
+
+With chronyd and gpsd both supporting PPS, and gpsd providing two different
+refclocks for PPS, there are three different recommended configurations:
+
+# First option
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS
+
+# Second option
+refclock SHM 1 refid GPS
+
+# Third option
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SHM 0 offset 0.5 delay 0.1 refid NMEA noselect
+
+Each option has some advantages:
+
+  o SOCK does not use polling (i.e. it can get samples earlier than SHM), but
+    it requires gpsd to be started after chronyd in order to connect to its
+    socket
+
+  o SOCK and SHM 1 can be more accurate than PPS if gpsd corrects for the
+    sawtooth error provided by the receiver in serial data
+
+  o PPS can be used with higher PPS rates (specified by the rate option), but
+    it requires a second refclock or another time source to pair pulses with
+    seconds, and the SHM 0 offset needs to be specified correctly to compensate
+    for the message delay, while gpsd can apply HW-specific information
+
+If the PPS signal is not available, or cannot be used for some reason, the only
+option is the message-based timing
+
+refclock SHM 0 offset 0.5 delay 0.1 refid GPS
+
+2.13. Does chrony support PTP?
+
+No, the Precision Time Protocol (PTP) is not supported as a protocol for
+synchronisation of clocks and there are no plans to support it. It is a complex
+protocol, which shares some issues with the NTP broadcast mode. One of the main
+differences between NTP and PTP is that PTP was designed to be easily supported
+in hardware (e.g. network switches and routers) in order to make more stable
+and accurate measurements. PTP relies on the hardware support. NTP does not
+rely on any support in the hardware, but if it had the same support as PTP, it
+could perform equally well.
+
+On Linux, chrony supports hardware clocks that some NICs have for PTP. They are
+called PTP hardware clocks (PHC). They can be used as reference clocks
+(specified by the refclock directive) and for hardware timestamping of NTP
+packets (enabled by the hwtimestamp directive) if the NIC can timestamp other
+packets than PTP, which is usually the case at least for transmitted packets.
+The ethtool -T command can be used to verify the timestamping support.
+
+As an experimental feature added in version 4.2, chrony can use PTP as a
+transport for NTP messages (NTP over PTP) to enable hardware timestamping on
+hardware which can timestamp PTP packets only. It can be enabled by the ptpport
+directive.
+
+2.14. Why are client log records dropped before reaching clientloglimit?
+
+The number of dropped client log records reported by the serverstats command
+can be increasing before the number of clients reported by the clients command
+reaches the maximum value corresponding to the memory limit set by the
+clientloglimit directive.
+
+This is due to the design of the data structure keeping the client records. It
+is a hash table which can store only up to 16 colliding addresses per slot. If
+a slot has more collisions and the table already has the maximum size, the
+oldest record will be dropped and replaced by the new client.
+
+Note that the size of the table is always a power of two and it can only grow.
+The limit set by the clientloglimit directive takes into account that two
+copies of the table exist when it is being resized. This means the actual
+memory usage reported by top and other utilities can be significantly smaller
+than the limit even when the maximum number of records is used.
+
+The absolute maximum number of client records kept at the same time is
+16777216.
+
+2.15. What happened to the commandkey and generatecommandkey directives?
+
+They were removed in version 2.2. Authentication is no longer supported in the
+command protocol. Commands that required authentication are now allowed only
+through a Unix domain socket, which is accessible only by the root and chrony
+users. If you need to configure chronyd remotely or locally without the root
+password, please consider using ssh and/or sudo to run chronyc under the root
+or chrony user on the host where chronyd is running.
+
+3. Computer is not synchronising
+
+This is the most common problem. There are a number of reasons, see the
+following questions.
+
+3.1. Behind a firewall?
+
+Check the Reach value printed by the chronyc's sources command. If it is zero,
+it means chronyd did not get any valid responses from the NTP server you are
+trying to use. If there is a firewall between you and the server, the packets
+might be blocked. Try using a tool like wireshark or tcpdump to see if you are
+getting any responses from the server.
+
+When chronyd is receiving responses from the servers, the output of the sources
+command issued few minutes after chronyd start might look like this:
+
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+^* foo.example.net               2   6   377    34   +484us[ -157us] +/-   30ms
+^- bar.example.net               2   6   377    34    +33ms[  +32ms] +/-   47ms
+^+ baz.example.net               3   6   377    35  -1397us[-2033us] +/-   60ms
+
+3.2. Are NTP servers specified with the offline option?
+
+Check that the chronyc's online and offline commands are used appropriately
+(e.g. in the system networking scripts). The activity command prints the number
+of sources that are currently online and offline. For example:
+
+200 OK
+3 sources online
+0 sources offline
+0 sources doing burst (return to online)
+0 sources doing burst (return to offline)
+0 sources with unknown address
+
+3.3. Is name resolution working correctly?
+
+NTP servers specified by their hostname (instead of an IP address) have to have
+their names resolved before chronyd can send any requests to them. If the
+activity command prints a non-zero number of sources with unknown address,
+there is an issue with the resolution. Typically, a DNS server is specified in
+/etc/resolv.conf. Make sure it is working correctly.
+
+Since chrony version 4.0, you can run chronyc -N sources -a command to print
+all sources, even those that do not have a known address yet, with their names
+as they were specified in the configuration. This can be useful to verify that
+the names specified in the configuration are used as expected.
+
+3.4. Is chronyd allowed to step the system clock?
+
+By default, chronyd adjusts the clock gradually by slowing it down or speeding
+it up. If the clock is too far from the true time, it will take a long time to
+correct the error. The System time value printed by the chronyc's tracking
+command is the remaining correction that needs to be applied to the system
+clock.
+
+The makestep directive can be used to allow chronyd to step the clock. For
+example, if chrony.conf had
+
+makestep 1 3
+
+the clock would be stepped in the first three updates if its offset was larger
+than one second. Normally, it is recommended to allow the step only in the
+first few updates, but in some cases (e.g. a computer without an RTC or virtual
+machine which can be suspended and resumed with an incorrect time) it might be
+necessary to allow the step on any clock update. The example above would change
+to
+
+makestep 1 -1
+
+3.5. Using NTS?
+
+The Network Time Security (NTS) mechanism uses Transport Layer Security (TLS)
+to establish the keys needed for authentication of NTP packets.
+
+Run the authdata command to check whether the key establishment was successful:
+
+# chronyc -N authdata
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256  33m    0    0    8  100
+bar.example.net              NTS     1   15  256  33m    0    0    8  100
+baz.example.net              NTS     1   15  256  33m    0    0    8  100
+
+The KeyID, Type, and KLen columns should have non-zero values. If they are
+zero, check the system log for error messages from chronyd. One possible cause
+of failure is a firewall blocking the client's connection to the server's TCP
+port 4460.
+
+Another possible cause of failure is a certificate that is failing to verify
+because the client's clock is wrong. This is a chicken-and-egg problem with
+NTS. You might need to manually correct the date, or temporarily disable NTS,
+in order to get NTS working. If your computer has an RTC and it is backed up by
+a good battery, this operation should be needed only once, assuming the RTC
+will be set periodically with the rtcsync directive, or compensated with the
+rtcfile directive and the -s option.
+
+If the computer does not have an RTC or battery, you can use the -s option
+without rtcfile directive to restore time of the last shutdown or reboot from
+the drift file. The clock will start behind the true time, but if the computer
+was not shut down for too long and the server's certificate was not renewed too
+close to its expiration, it should be sufficient for the time checks to
+succeed.
+
+If you run your own server, you can use a self-signed certificate covering all
+dates where the client can start (e.g. years 1970-2100). The certificate needs
+to be installed on the client and specified with the ntstrustedcerts directive.
+The server can have multiple names and certificates. To avoid trusting a
+certificate for too long, a new certificate can be added to the server
+periodically (e.g. once per year) and the client can have the server name and
+trusted certificate updated automatically (e.g. using a package repository, or
+a cron script downloading the files directly from the server over HTTPS). A
+client that was shut down for years will still be able to synchronise its clock
+and perform the update as long as the server keeps the old certificate.
+
+As a last resort, you can disable the time checks by the nocerttimecheck
+directive. This has some important security implications. To reduce the
+security risk, you can use the nosystemcert and ntstrustedcerts directives to
+disable the system's default trusted certificate authorities and trust only a
+minimal set of selected authorities needed to validate the certificates of used
+NTP servers.
+
+3.6. Using a Windows NTP server?
+
+A common issue with Windows NTP servers is that they report a very large root
+dispersion (e.g. three seconds or more), which causes chronyd to ignore the
+server for being too inaccurate. The sources command might show a valid
+measurement, but the server is not selected for synchronisation. You can check
+the root dispersion of the server with the chronyc's ntpdata command.
+
+The maxdistance value needs to be increased in chrony.conf to enable
+synchronisation to such a server. For example:
+
+maxdistance 16.0
+
+3.7. An unreachable source is selected?
+
+When chronyd is configured with multiple time sources, it tries to select the
+most accurate and stable sources for synchronisation of the system clock. They
+are marked with the * or + symbol in the report printed by the sources command.
+
+When the best source (marked with the * symbol) becomes unreachable (e.g. NTP
+server stops responding), chronyd will not immediately switch to the second
+best source in an attempt to minimise the error of the clock. It will let the
+clock run free for as long as its estimated error (in terms of root distance)
+based on previous measurements is smaller than the estimated error of the
+second source, and there is still an interval which contains some measurements
+from both sources.
+
+If the first source was significantly better than the second source, it can
+take many hours before the second source is selected, depending on its polling
+interval. You can force a faster reselection by increasing the clock error rate
+(maxclockerror directive), shortening the polling interval (maxpoll option), or
+reducing the number of samples (maxsamples option).
+
+3.8. Does selected source drop new measurements?
+
+chronyd can drop a large number of successive NTP measurements if they are not
+passing some of the NTP tests. The sources command can report for a selected
+source the fully-reachable value of 377 in the Reach column and at the same
+time a LastRx value that is much larger than the current polling interval. If
+the source is online, this indicates that a number of measurements was dropped.
+You can use the ntpdata command to check the NTP tests for the last
+measurement. Usually, it is the test C which fails.
+
+This can be an issue when there is a long-lasting increase in the measured
+delay, e.g. due to a routing change in the network. Unfortunately, chronyd does
+not know for how long it should wait for the delay to come back to the original
+values, or whether it is a permanent increase and it should start from scratch.
+
+The test C is an adaptive filter. It can take many hours before it accepts a
+measurement with the larger delay, and even much longer before it drops all
+measurements with smaller delay, which determine an expected delay used by the
+test. You can use the reset sources command to drop all measurements
+immediately (available in chrony 4.0 and later). If this issue happens
+frequently, you can effectively disable the test by setting the
+maxdelaydevratio option to a very large value (e.g. 1000000), or speed up the
+recovery by increasing the clock error rate with the maxclockerror directive.
+
+3.9. Using a PPS reference clock?
+
+A pulse-per-second (PPS) reference clock requires a non-PPS time source to
+determine which second of UTC corresponds to each pulse. If it is another
+reference clock specified with the lock option in the refclock directive, the
+offset between the two reference clocks must be smaller than 0.4 seconds (0.2
+seconds with chrony versions before 4.1) in order for the PPS reference clock
+to work. With NMEA reference clocks it is common to have a larger offset. It
+needs to be corrected with the offset option.
+
+One approach to find out a good value of the offset option is to configure the
+reference clocks with the noselect option and compare them to an NTP server.
+For example, if the sourcestats command showed
+
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+PPS0                        0   0     0     +0.000   2000.000     +0ns  4000ms
+NMEA                       58  30   231    -96.494     38.406   +504ms  6080us
+foo.example.net             7   3   200     -2.991     16.141   -107us   492us
+
+the offset of the NMEA source would need to be increased by about 0.504
+seconds. It does not have to be very accurate. As long as the offset of the
+NMEA reference clock stays below the limit, the PPS reference clock should be
+able to determine the seconds corresponding to the pulses and allow the samples
+to be used for synchronisation.
+
+4. Issues with chronyc
+
+4.1. I keep getting the error 506 Cannot talk to daemon
+
+When accessing chronyd remotely, make sure that the chrony.conf file (on the
+computer where chronyd is running) has a cmdallow entry for the computer you
+are running chronyc on and an appropriate bindcmdaddress directive. This is not
+necessary for localhost.
+
+Perhaps chronyd is not running. Try using the ps command (e.g. on Linux, ps
+-auxw) to see if it is running. Or try netstat -a and see if the UDP port 323
+is listening. If chronyd is not running, you might have a problem with the way
+you are trying to start it (e.g. at boot time).
+
+Perhaps you have a firewall set up in a way that blocks packets on the UDP port
+323. You need to amend the firewall configuration in this case.
+
+4.2. I keep getting the error 501 Not authorised
+
+This error indicates that chronyc sent the command to chronyd using a UDP
+socket instead of the Unix domain socket (e.g. /var/run/chrony/chronyd.sock),
+which is required for some commands. For security reasons, only the root and
+chrony users are allowed to access the socket.
+
+It is also possible that the socket does not exist. chronyd will not create the
+socket if the directory has a wrong owner or permissions. In this case there
+should be an error message from chronyd in the system log.
+
+4.3. What is the reference ID reported by the tracking command?
+
+The reference ID is a 32-bit value used in NTP to prevent synchronisation
+loops.
+
+In chrony versions before 3.0 it was printed in the quad-dotted notation, even
+if the reference source did not actually have an IPv4 address. For IPv4
+addresses, the reference ID is equal to the address, but for IPv6 addresses it
+is the first 32 bits of the MD5 sum of the address. For reference clocks, the
+reference ID is the value specified with the refid option in the refclock
+directive.
+
+Since version 3.0, the reference ID is printed as a hexadecimal number to avoid
+confusion with IPv4 addresses.
+
+If you need to get the IP address of the current reference source, use the -n
+option to disable resolving of IP addresses and read the second field (printed
+in parentheses) on the Reference ID line.
+
+4.4. Is the chronyc / chronyd protocol documented anywhere?
+
+Only by the source code. See cmdmon.c (chronyd side) and client.c (chronyc
+side).
+
+Note that this protocol is not compatible with the mode 6 or mode 7 protocol
+supported by ntpd, i.e. the ntpq or ntpdc utility cannot be used to monitor
+chronyd, and chronyc cannot be used to monitor ntpd.
+
+5. Real-time clock issues
+
+5.1. What is the real-time clock (RTC)?
+
+This is the clock which keeps the time even when your computer is turned off.
+It is used to initialise the system clock on boot. It normally does not drift
+more than few seconds per day.
+
+There are two approaches how chronyd can work with it. One is to use the
+rtcsync directive, which tells chronyd to enable a kernel mode which sets the
+RTC from the system clock every 11 minutes. chronyd itself will not touch the
+RTC. If the computer is not turned off for a long time, the RTC should still be
+close to the true time when the system clock will be initialised from it on the
+next boot.
+
+The other option is to use the rtcfile directive, which tells chronyd to
+monitor the rate at which the RTC gains or loses time. When chronyd is started
+with the -s option on the next boot, it will set the system time from the RTC
+and also compensate for the drift it has measured previously. The rtcautotrim
+directive can be used to keep the RTC close to the true time, but it is not
+strictly necessary if its only purpose is to set the system clock when chronyd
+is started on boot. See the documentation for details.
+
+5.2. Does hwclock have to be disabled?
+
+The hwclock program is run by default in the boot and/or shutdown scripts in
+some Linux installations. With the kernel RTC synchronisation (rtcsync
+directive), the RTC will be set also every 11 minutes as long as the system
+clock is synchronised. If you want to use chronyd's RTC monitoring (rtcfile
+directive), it is important to disable hwclock in the shutdown procedure. If
+you do not do that, it will overwrite the RTC with a new value, unknown to
+chronyd. At the next reboot, chronyd started with the -s option will compensate
+this (wrong) time with its estimate of how far the RTC has drifted whilst the
+power was off, giving a meaningless initial system time.
+
+There is no need to remove hwclock from the boot process, as long as chronyd is
+started after it has run.
+
+5.3. I just keep getting the 513 RTC driver not running message
+
+For the real-time clock support to work, you need the following three things
+
+  o an RTC in your computer
+
+  o a Linux kernel with enabled RTC support
+
+  o an rtcfile directive in your chrony.conf file
+
+5.4. I get Could not open /dev/rtc, Device or resource busy in my syslog file
+
+Some other program running on the system might be using the device.
+
+5.5. When I start chronyd, the log says Could not enable RTC interrupt :
+Invalid argument (or it may say disable)
+
+Your real-time clock hardware might not support the required ioctl requests:
+
+  o RTC_UIE_ON
+
+  o RTC_UIE_OFF
+
+A possible solution could be to build the Linux kernel with support for
+software emulation instead; try enabling the following configuration option
+when building the Linux kernel:
+
+  o CONFIG_RTC_INTF_DEV_UIE_EMUL
+
+5.6. What if my computer does not have an RTC or backup battery?
+
+In this case you can still use the -s option to set the system clock to the
+last modification time of the drift file, which should correspond to the system
+time when chronyd was previously stopped. The initial system time will be
+increasing across reboots and applications started after chronyd will not
+observe backward steps.
+
+6. NTP-specific issues
+
+6.1. Can chronyd be driven from broadcast/multicast NTP servers?
+
+No, the broadcast/multicast client mode is not supported and there is currently
+no plan to implement it. While this mode can simplify configuration of clients
+in large networks, it is inherently less accurate and less secure (even with
+authentication) than the ordinary client/server mode.
+
+When configuring a large number of clients in a network, it is recommended to
+use the pool directive with a DNS name which resolves to addresses of multiple
+NTP servers. The clients will automatically replace the servers when they
+become unreachable, or otherwise unsuitable for synchronisation, with new
+servers from the pool.
+
+Even with very modest hardware, an NTP server can serve time to hundreds of
+thousands of clients using the ordinary client/server mode.
+
+6.2. Can chronyd transmit broadcast NTP packets?
+
+Yes, the broadcast directive can be used to enable the broadcast server mode to
+serve time to clients in the network which support the broadcast client mode
+(it is not supported in chronyd). Note that this mode should generally be
+avoided. See the previous question.
+
+6.3. Can chronyd keep the system clock a fixed offset away from real time?
+
+Yes. Starting from version 3.0, an offset can be specified by the offset option
+for all time sources in the chrony.conf file.
+
+6.4. What happens if the network connection is dropped without using chronyc's
+offline command first?
+
+chronyd will keep trying to access the sources that it thinks are online, and
+it will take longer before new measurements are actually made and the clock is
+corrected when the network is connected again. If the sources were set to
+offline, chronyd would make new measurements immediately after issuing the
+online command.
+
+Unless the network connection lasts only few minutes (less than the maximum
+polling interval), the delay is usually not a problem, and it might be
+acceptable to keep all sources online all the time.
+
+6.5. Why is an offset measured between two computers synchronised to each
+another?
+
+When two computers are synchronised to each other using the client/server or
+symmetric NTP mode, there is an expectation that NTP measurements between the
+two computers made on both ends show an average offset close to zero.
+
+With chronyd that can be expected only when the interleaved mode is enabled by
+the xleave option. Otherwise, chronyd will use different transmit timestamps
+(e.g. daemon timestamp vs kernel timestamp) for serving time and
+synchronisation of its own clock, which will cause the other computer to
+measure a significant offset.
+
+7. Operation
+
+7.1. What clocks does chronyd use?
+
+There are several different clocks used by chronyd:
+
+  o System clock: software clock maintained by the kernel. It is the main clock
+    used by applications running on the computer. It is synchronised by chronyd
+    to its NTP clock, unless started with the -x option.
+
+  o NTP clock: software clock (virtual) based on the system clock and internal
+    to chronyd. It keeps the best estimate of the true time according to the
+    configured time sources, which is served to NTP clients unless time
+    smoothing is enabled by the smoothtime directive. The System time value in
+    the tracking report is the current offset between the system and NTP clock.
+
+  o Real-time clock (RTC): hardware clock keeping time even when the computer
+    is turned off. It is used by the kernel to initialise the system clock on
+    boot and also by chronyd to compensate for its measured drift if configured
+    with the rtcfile directive and started with the -s option. The clock can be
+    kept accurate only by stepping enabled by the rtcsync or rtcautotrim
+    directive.
+
+  o Reference clock: hardware clock used as a time source. It is specified by
+    the refclock directive.
+
+  o NIC clock (also known as PTP hardware clock): hardware clock timestamping
+    packets received and transmitted by a network device specified by the
+    hwtimestamp directive. The clock is expected to be running free. It is not
+    synchronised by chronyd. Its offset is tracked relative to the NTP clock in
+    order to convert the hardware timestamps.
+
+8. Operating systems
+
+8.1. Does chrony support Windows?
+
+No. The chronyc program (the command-line client used for configuring chronyd
+while it is running) has been successfully built and run under Cygwin in the
+past. chronyd is not portable, because part of it is very system-dependent. It
+needs adapting to work with Windows' equivalent of the adjtimex() call, and it
+needs to be made to work as a service.
+
+8.2. Are there any plans to support Windows?
+
+We have no plans to do this. Anyone is welcome to pick this work up and
+contribute it back to the project.
+
+Last updated 2022-08-29 15:04:33 +0200
diff --git a/INSTALL b/INSTALL
new file mode 100644
index 0000000..e73dcd2
--- /dev/null
+++ b/INSTALL
@@ -0,0 +1,165 @@
+Installation
+
+The software is distributed as source code which has to be compiled. The source
+code is supplied in the form of a gzipped tar file, which unpacks to a
+subdirectory identifying the name and version of the program.
+
+A C compiler (e.g. gcc or clang) and GNU Make are needed to build chrony. The
+following libraries with their development files, and programs, are needed to
+enable optional features:
+
+  o pkg-config: detection of development libraries
+
+  o Nettle, GnuTLS, NSS, or LibTomCrypt: secure hash functions (SECHASH)
+
+  o libcap: dropping root privileges on Linux (DROPROOT)
+
+  o libseccomp: system call filter on Linux (SCFILTER)
+
+  o GnuTLS and Nettle: Network Time Security (NTS)
+
+  o Editline: line editing in chronyc (READLINE)
+
+  o timepps.h header: PPS reference clock
+
+  o Asciidoctor: documentation in HTML format
+
+  o Bash: test suite
+
+The following programs are needed when building chrony from the git repository
+instead of a released tar file:
+
+  o Asciidoctor: manual pages
+
+  o Bison: parser for chronyc settime command
+
+After unpacking the source code, change directory into it, and type
+
+./configure
+
+This is a shell script that automatically determines the system type. There is
+an optional parameter --prefix, which indicates the directory tree where the
+software should be installed. For example,
+
+./configure --prefix=/opt/free
+
+will install the chronyd daemon into /opt/free/sbin and the chronyc control
+program into /opt/free/bin. The default value for the prefix is /usr/local.
+
+The configure script assumes you want to use gcc as your compiler. If you want
+to use a different compiler, you can configure this way:
+
+CC=cc ./configure --prefix=/opt/free
+
+for Bourne-family shells, or
+
+setenv CC cc
+setenv CFLAGS -O
+./configure --prefix=/opt/free
+
+for C-family shells.
+
+If the software cannot (yet) be built on your system, an error message will be
+shown. Otherwise, Makefile will be generated.
+
+On Linux, if development files for the libcap library are available, chronyd
+will be built with support for dropping root privileges. On other systems no
+extra library is needed. The default user which chronyd should run as can be
+specified with the --with-user option of the configure script.
+
+If development files for the POSIX threads library are available, chronyd will
+be built with support for asynchronous resolving of hostnames specified in the
+server, peer, and pool directives. This allows chronyd operating as a server to
+respond to client requests when resolving a hostname. If you don't want to
+enable the support, specify the --disable-asyncdns flag to configure.
+
+If development files for the Nettle, NSS, or libtomcrypt library are available,
+chronyd will be built with support for other cryptographic hash functions than
+MD5, which can be used for NTP authentication with a symmetric key. If you
+don't want to enable the support, specify the --disable-sechash flag to
+configure.
+
+If development files for the editline library are available, chronyc will be
+built with line editing support. If you don't want this, specify the
+--disable-readline flag to configure.
+
+If a timepps.h header is available (e.g. from the LinuxPPS project), chronyd
+will be built with PPS API reference clock driver. If the header is installed
+in a location that isn't normally searched by the compiler, you can add it to
+the searched locations by setting the CPPFLAGS variable to -I/path/to/timepps.
+
+The --help option can be specified to configure to print all options supported
+by the script.
+
+Now type
+
+make
+
+to build the programs.
+
+If you want to build the manual in HTML, type
+
+make docs
+
+Once the programs have been successfully compiled, they need to be installed in
+their target locations. This step normally needs to be performed by the
+superuser, and requires the following command to be entered.
+
+make install
+
+This will install the binaries and man pages.
+
+To install the HTML version of the manual, enter the command
+
+make install-docs
+
+Now that the software is successfully installed, the next step is to set up a
+configuration file. The default location of the file is /etc/chrony.conf.
+Several examples of configuration with comments are included in the examples
+directory. Suppose you want to use public NTP servers from the pool.ntp.org
+project as your time reference. A minimal useful configuration file could be
+
+pool pool.ntp.org iburst
+makestep 1.0 3
+rtcsync
+
+Then, chronyd can be run. For security reasons, it's recommended to create an
+unprivileged user for chronyd and specify it with the -u command-line option or
+the user directive in the configuration file, or set the default user with the
+--with-user configure option before building.
+
+Support for system call filtering
+
+chronyd can be built with support for the Linux secure computing (seccomp)
+facility. This requires development files for the libseccomp library and the
+--enable-scfilter option specified to configure. The -F option of chronyd will
+enable a system call filter, which should significantly reduce the kernel
+attack surface and possibly prevent kernel exploits from chronyd if it is
+compromised.
+
+Extra options for package builders
+
+The configure and make procedures have some extra options that may be useful if
+you are building a distribution package for chrony.
+
+The --mandir=DIR option to configure specifies an installation directory for
+the man pages. This overrides the man subdirectory of the argument to the
+--prefix option.
+
+./configure --prefix=/usr --mandir=/usr/share/man
+
+to set both options together.
+
+The final option is the DESTDIR option to the make command. For example, you
+could use the commands
+
+./configure --prefix=/usr --mandir=/usr/share/man
+make all docs
+make install DESTDIR=./tmp
+cd tmp
+tar cvf - . | gzip -9 > chrony.tar.gz
+
+to build a package. When untarred within the root directory, this will install
+the files to the intended final locations.
+
+Last updated 2022-08-29 15:04:33 +0200
diff --git a/Makefile.in b/Makefile.in
new file mode 100644
index 0000000..ef100a4
--- /dev/null
+++ b/Makefile.in
@@ -0,0 +1,139 @@
+##################################################
+#
+# chronyd/chronyc - Programs for keeping computer clocks accurate.
+# 
+# Copyright (C) Richard P. Curnow  1997-2003
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of version 2 of the GNU General Public License as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# =======================================================================
+#
+# Makefile template
+
+SYSCONFDIR = @SYSCONFDIR@
+BINDIR = @BINDIR@
+SBINDIR = @SBINDIR@
+LOCALSTATEDIR = @LOCALSTATEDIR@
+CHRONYVARDIR = @CHRONYVARDIR@
+DESTDIR =
+
+CC = @CC@
+CFLAGS = @CFLAGS@
+CPPFLAGS = @CPPFLAGS@
+LDFLAGS = @LDFLAGS@
+
+EXTRA_OBJS = @EXTRA_OBJS@
+
+OBJS = array.o cmdparse.o conf.o local.o logging.o main.o memory.o quantiles.o \
+       reference.o regress.o rtc.o samplefilt.o sched.o socket.o sources.o sourcestats.o \
+       stubs.o smooth.o sys.o sys_null.o tempcomp.o util.o $(EXTRA_OBJS)
+
+EXTRA_CLI_OBJS = @EXTRA_CLI_OBJS@
+
+CLI_OBJS = array.o client.o cmdparse.o getdate.o memory.o nameserv.o \
+           pktlength.o socket.o util.o $(EXTRA_CLI_OBJS)
+
+ALL_OBJS = $(OBJS) $(CLI_OBJS)
+
+LIBS = @LIBS@
+EXTRA_LIBS = @EXTRA_LIBS@
+EXTRA_CLI_LIBS = @EXTRA_CLI_LIBS@
+
+# Until we have a main procedure we can link, just build object files
+# to test compilation
+
+all : chronyd chronyc
+
+chronyd : $(OBJS)
+	$(CC) $(CFLAGS) -o chronyd $(OBJS) $(LDFLAGS) $(LIBS) $(EXTRA_LIBS)
+
+chronyc : $(CLI_OBJS)
+	$(CC) $(CFLAGS) -o chronyc $(CLI_OBJS) $(LDFLAGS) $(LIBS) $(EXTRA_CLI_LIBS)
+
+distclean : clean
+	$(MAKE) -C doc distclean
+	$(MAKE) -C test/unit distclean
+	-rm -f .DS_Store
+	-rm -f Makefile config.h config.log
+
+clean :
+	$(MAKE) -C test/unit clean
+	-rm -f *.o *.s chronyc chronyd core.* *~
+	-rm -f *.gcda *.gcno
+	-rm -rf .deps
+	-rm -rf *.dSYM
+
+getdate.c : getdate.y
+	bison -o getdate.c getdate.y
+
+# This can be used to force regeneration of getdate.c
+getdate :
+	bison -o getdate.c getdate.y
+
+# For install, don't use the install command, because its switches
+# seem to vary between systems.
+
+install: chronyd chronyc
+	[ -d $(DESTDIR)$(SYSCONFDIR) ] || mkdir -p $(DESTDIR)$(SYSCONFDIR)
+	[ -d $(DESTDIR)$(SBINDIR) ] || mkdir -p $(DESTDIR)$(SBINDIR)
+	[ -d $(DESTDIR)$(BINDIR) ] || mkdir -p $(DESTDIR)$(BINDIR)
+	[ -d $(DESTDIR)$(CHRONYVARDIR) ] || mkdir -p $(DESTDIR)$(CHRONYVARDIR)
+	if [ -f $(DESTDIR)$(SBINDIR)/chronyd ]; then rm -f $(DESTDIR)$(SBINDIR)/chronyd ; fi
+	if [ -f $(DESTDIR)$(BINDIR)/chronyc ]; then rm -f $(DESTDIR)$(BINDIR)/chronyc ; fi
+	cp chronyd $(DESTDIR)$(SBINDIR)/chronyd
+	chmod 755 $(DESTDIR)$(SBINDIR)/chronyd
+	cp chronyc $(DESTDIR)$(BINDIR)/chronyc
+	chmod 755 $(DESTDIR)$(BINDIR)/chronyc
+	$(MAKE) -C doc install
+
+docs :
+	$(MAKE) -C doc docs
+
+install-docs :
+	$(MAKE) -C doc install-docs
+
+%.o : %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
+
+%.s : %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -S $<
+
+quickcheck : chronyd chronyc
+	$(MAKE) -C test/unit check
+	cd test/simulation && ./run
+	cd test/system && ./run
+
+check : chronyd chronyc
+	$(MAKE) -C test/unit check
+	cd test/simulation && ./run -i 20 -m 2
+	cd test/system && ./run
+
+print-chronyd-objects :
+	@echo $(OBJS)
+
+Makefile : Makefile.in configure
+	@echo
+	@echo Makefile needs to be regenerated, run ./configure
+	@echo
+	@exit 1
+
+.deps:
+	@mkdir .deps
+
+.deps/%.d: %.c | .deps
+	@$(CC) -MM $(CPPFLAGS) -MT '$(<:%.c=%.o) $@' $< -o $@
+
+ifndef NODEPS
+-include $(ALL_OBJS:%.o=.deps/%.d)
+endif
diff --git a/NEWS b/NEWS
new file mode 100644
index 0000000..8673fd6
--- /dev/null
+++ b/NEWS
@@ -0,0 +1,977 @@
+New in version 4.3
+==================
+
+Enhancements
+------------
+* Add local option to refclock directive to stabilise system clock
+  with more stable free-running clock (e.g. TCXO, OCXO)
+* Add maxdelayquant option to server/pool/peer directive to replace
+  maxdelaydevratio filter with long-term quantile-based filtering
+* Add selection option to log directive
+* Allow external PPS in PHC refclock without configurable pin
+* Don't accept first interleaved response to minimise error in delay
+* Don't use arc4random on Linux to avoid server performance loss
+* Improve filter option to better handle missing NTP samples
+* Improve stability with hardware timestamping and PHC refclock
+* Update seccomp filter
+
+Bug fixes
+---------
+* Fix waitsync command to reconnect when not getting response
+
+New in version 4.2
+==================
+
+Enhancements
+------------
+* Add support for NTPv4 extension field improving synchronisation
+  stability and resolution of root delay and dispersion (experimental)
+* Add support for NTP over PTP (experimental)
+* Add support for AES-CMAC and hash functions in GnuTLS
+* Improve server interleaved mode to be more reliable and support
+  multiple clients behind NAT
+* Update seccomp filter
+* Add statistics about interleaved mode to serverstats report
+
+Bug fixes
+---------
+* Fix RTC support with 64-bit time_t on 32-bit Linux
+* Fix seccomp filter to work correctly with bind*device directives
+* Suppress kernel adjustments of system clock (dosynctodr) on illumos
+
+Other changes
+-------------
+* Switch Solaris support to illumos
+
+New in version 4.1
+==================
+
+Enhancements
+------------
+* Add support for NTS servers specified by IP address (matching
+  Subject Alternative Name in server certificate)
+* Add source-specific configuration of trusted certificates
+* Allow multiple files and directories with trusted certificates
+* Allow multiple pairs of server keys and certificates
+* Add copy option to server/pool directive
+* Increase PPS lock limit to 40% of pulse interval
+* Perform source selection immediately after loading dump files
+* Reload dump files for addresses negotiated by NTS-KE server
+* Update seccomp filter and add less restrictive level
+* Restart ongoing name resolution on online command
+
+Bug fixes
+---------
+* Fix responding to IPv4 command requests on FreeBSD
+* Fix dump files to not include uncorrected offset
+* Fix initstepslew to accept time from own NTP clients
+* Reset NTP address and port when no longer negotiated by NTS-KE server
+
+New in version 4.0
+==================
+
+Enhancements
+------------
+* Add support for Network Time Security (NTS) authentication
+* Add support for AES-CMAC keys (AES128, AES256) with Nettle
+* Add authselectmode directive to control selection of unauthenticated sources
+* Add binddevice, bindacqdevice, bindcmddevice directives
+* Add confdir directive to better support fragmented configuration
+* Add sourcedir directive and "reload sources" command to support dynamic
+  NTP sources specified in files
+* Add clockprecision directive
+* Add dscp directive to set Differentiated Services Code Point (DSCP)
+* Add -L option to limit log messages by severity
+* Add -p option to print whole configuration with included files
+* Add -U option to allow start under non-root user
+* Allow maxsamples to be set to 1 for faster update with -q/-Q option
+* Avoid replacing NTP sources with sources that have unreachable address
+* Improve pools to repeat name resolution to get "maxsources" sources
+* Improve source selection with trusted sources
+* Improve NTP loop test to prevent synchronisation to itself
+* Repeat iburst when NTP source is switched from offline state to online
+* Update clock synchronisation status and leap status more frequently
+* Update seccomp filter
+* Add "add pool" command
+* Add "reset sources" command to drop all measurements
+* Add authdata command to print details about NTP authentication
+* Add selectdata command to print details about source selection
+* Add -N option and sourcename command to print original names of sources
+* Add -a option to some commands to print also unresolved sources
+* Add -k, -p, -r options to clients command to select, limit, reset data
+
+Bug fixes
+---------
+* Don't set interface for NTP responses to allow asymmetric routing
+* Handle RTCs that don't support interrupts
+* Respond to command requests with correct address on multihomed hosts
+
+Removed features
+----------------
+* Drop support for RIPEMD keys (RMD128, RMD160, RMD256, RMD320)
+* Drop support for long (non-standard) MACs in NTPv4 packets (chrony 2.x
+  clients using non-MD5/SHA1 keys need to use option "version 3")
+* Drop support for line editing with GNU Readline
+
+New in version 3.5.1
+====================
+
+Security fixes
+--------------
+* Create new file when writing pidfile (CVE-2020-14367)
+
+New in version 3.5
+==================
+
+Enhancements
+------------
+* Add support for more accurate reading of PHC on Linux 5.0
+* Add support for hardware timestamping on interfaces with read-only
+  timestamping configuration
+* Add support for memory locking and real-time priority on FreeBSD,
+  NetBSD, Solaris
+* Update seccomp filter to work on more architectures
+* Validate refclock driver options
+
+Bug fixes
+---------
+* Fix bindaddress directive on FreeBSD
+* Fix transposition of hardware RX timestamp on Linux 4.13 and later
+* Fix building on non-glibc systems
+
+New in version 3.4
+==================
+
+Enhancements
+------------
+* Add filter option to server/pool/peer directive
+* Add minsamples and maxsamples options to hwtimestamp directive
+* Add support for faster frequency adjustments in Linux 4.19
+* Change default pidfile to /var/run/chrony/chronyd.pid to allow
+  chronyd without root privileges to remove it on exit
+* Disable sub-second polling intervals for distant NTP sources
+* Extend range of supported sub-second polling intervals
+* Get/set IPv4 destination/source address of NTP packets on FreeBSD
+* Make burst options and command useful with short polling intervals
+* Modify auto_offline option to activate when sending request failed
+* Respond from interface that received NTP request if possible
+* Add onoffline command to switch between online and offline state
+  according to current system network configuration
+* Improve example NetworkManager dispatcher script
+
+Bug fixes
+---------
+* Avoid waiting in Linux getrandom system call
+* Fix PPS support on FreeBSD and NetBSD
+
+New in version 3.3
+==================
+
+Enhancements
+------------
+* Add burst option to server/pool directive
+* Add stratum and tai options to refclock directive
+* Add support for Nettle crypto library
+* Add workaround for missing kernel receive timestamps on Linux
+* Wait for late hardware transmit timestamps
+* Improve source selection with unreachable sources
+* Improve protection against replay attacks on symmetric mode
+* Allow PHC refclock to use socket in /var/run/chrony
+* Add shutdown command to stop chronyd
+* Simplify format of response to manual list command
+* Improve handling of unknown responses in chronyc
+
+Bug fixes
+---------
+* Respond to NTPv1 client requests with zero mode
+* Fix -x option to not require CAP_SYS_TIME under non-root user
+* Fix acquisitionport directive to work with privilege separation
+* Fix handling of socket errors on Linux to avoid high CPU usage
+* Fix chronyc to not get stuck in infinite loop after clock step
+
+New in version 3.2
+==================
+
+Enhancements
+------------
+* Improve stability with NTP sources and reference clocks
+* Improve stability with hardware timestamping
+* Improve support for NTP interleaved modes
+* Control frequency of system clock on macOS 10.13 and later
+* Set TAI-UTC offset of system clock with leapsectz directive
+* Minimise data in client requests to improve privacy
+* Allow transmit-only hardware timestamping
+* Add support for new timestamping options introduced in Linux 4.13
+* Add root delay, root dispersion and maximum error to tracking log
+* Add mindelay and asymmetry options to server/peer/pool directive
+* Add extpps option to PHC refclock to timestamp external PPS signal
+* Add pps option to refclock directive to treat any refclock as PPS
+* Add width option to refclock directive to filter wrong pulse edges
+* Add rxfilter option to hwtimestamp directive
+* Add -x option to disable control of system clock
+* Add -l option to log to specified file instead of syslog
+* Allow multiple command-line options to be specified together
+* Allow starting without root privileges with -Q option
+* Update seccomp filter for new glibc versions
+* Dump history on exit by default with dumpdir directive
+* Use hardening compiler options by default
+
+Bug fixes
+---------
+* Don't drop PHC samples with low-resolution system clock
+* Ignore outliers in PHC tracking, RTC tracking, manual input
+* Increase polling interval when peer is not responding
+* Exit with error message when include directive fails
+* Don't allow slash after hostname in allow/deny directive/command
+* Try to connect to all addresses in chronyc before giving up
+
+New in version 3.1
+==================
+
+Enhancements
+------------
+* Add support for precise cross timestamping of PHC on Linux
+* Add minpoll, precision, nocrossts options to hwtimestamp directive
+* Add rawmeasurements option to log directive and modify measurements
+  option to log only valid measurements from synchronised sources
+* Allow sub-second polling interval with NTP sources
+
+Bug fixes
+---------
+* Fix time smoothing in interleaved mode
+
+New in version 3.0
+==================
+
+Enhancements
+------------
+* Add support for software and hardware timestamping on Linux
+* Add support for client/server and symmetric interleaved modes
+* Add support for MS-SNTP authentication in Samba
+* Add support for truncated MACs in NTPv4 packets
+* Estimate and correct for asymmetric network jitter
+* Increase default minsamples and polltarget to improve stability
+  with very low jitter
+* Add maxjitter directive to limit source selection by jitter
+* Add offset option to server/pool/peer directive
+* Add maxlockage option to refclock directive
+* Add -t option to chronyd to exit after specified time
+* Add partial protection against replay attacks on symmetric mode
+* Don't reset polling interval when switching sources to online state
+* Allow rate limiting with very short intervals
+* Improve maximum server throughput on Linux and NetBSD
+* Remove dump files after start
+* Add tab-completion to chronyc with libedit/readline
+* Add ntpdata command to print details about NTP measurements
+* Allow all source options to be set in add server/peer command
+* Indicate truncated addresses/hostnames in chronyc output
+* Print reference IDs as hexadecimal numbers to avoid confusion with
+  IPv4 addresses
+
+Bug fixes
+---------
+* Fix crash with disabled asynchronous name resolving
+
+New in version 2.4.1
+====================
+
+Bug fixes
+---------
+* Fix processing of kernel timestamps on non-Linux systems
+* Fix crash with smoothtime directive
+* Fix validation of refclock sample times
+* Fix parsing of refclock directive
+
+New in version 2.4
+==================
+
+Enhancements
+------------
+* Add orphan option to local directive for orphan mode compatible with ntpd
+* Add distance option to local directive to set activation threshold
+  (1 second by default)
+* Add maxdrift directive to set maximum allowed drift of system clock
+* Try to replace NTP sources exceeding maximum distance
+* Randomise source replacement to avoid getting stuck with bad sources
+* Randomise selection of sources from pools on start
+* Ignore reference timestamp as ntpd doesn't always set it correctly
+* Modify tracking report to use same values as seen by NTP clients
+* Add -c option to chronyc to write reports in CSV format
+* Provide detailed manual pages
+
+Bug fixes
+---------
+* Fix SOCK refclock to work correctly when not specified as last refclock
+* Fix initstepslew and -q/-Q options to accept time from own NTP clients
+* Fix authentication with keys using 512-bit hash functions
+* Fix crash on exit when multiple signals are received
+* Fix conversion of very small floating-point numbers in command packets
+
+Removed features
+----------------
+* Drop documentation in Texinfo format
+
+New in version 2.3
+==================
+
+Enhancements
+------------
+* Add support for NTP and command response rate limiting
+* Add support for dropping root privileges on Mac OS X, FreeBSD, Solaris
+* Add require and trust options for source selection
+* Enable logchange by default (1 second threshold)
+* Set RTC on Mac OS X with rtcsync directive
+* Allow binding to NTP port after dropping root privileges on NetBSD
+* Drop CAP_NET_BIND_SERVICE capability on Linux when NTP port is disabled
+* Resolve names in separate process when seccomp filter is enabled
+* Replace old records in client log when memory limit is reached
+* Don't reveal local time and synchronisation state in client packets
+* Don't keep client sockets open for longer than necessary
+* Ignore poll in KoD RATE packets as ntpd doesn't always set it correctly
+* Warn when using keys shorter than 80 bits
+* Add keygen command to generate random keys easily
+* Add serverstats command to report NTP and command packet statistics
+
+Bug fixes
+---------
+* Fix clock correction after making step on Mac OS X
+* Fix building on Solaris
+
+New in version 2.2.1
+====================
+
+Security fixes
+--------------
+* Restrict authentication of NTP server/peer to specified key (CVE-2016-1567)
+
+New in version 2.2
+==================
+
+Enhancements
+------------
+* Add support for configuration and monitoring over Unix domain socket
+  (accessible by root or chrony user when root privileges are dropped)
+* Add support for system call filtering with seccomp on Linux (experimental)
+* Add support for dropping root privileges on NetBSD
+* Control frequency of system clock on FreeBSD, NetBSD, Solaris
+* Add system leap second handling mode on FreeBSD, NetBSD, Solaris
+* Add dynamic drift removal on Mac OS X
+* Add support for setting real-time priority on Mac OS X
+* Add maxdistance directive to limit source selection by root distance
+  (3 seconds by default)
+* Add refresh command to get new addresses of NTP sources
+* Allow wildcard patterns in include directive
+* Restore time from driftfile with -s option if later than RTC time
+* Add configure option to set default hwclockfile
+* Add -d option to chronyc to enable debug messages
+* Allow multiple addresses to be specified for chronyc with -h option
+  and reconnect when no valid reply is received
+* Make check interval in waitsync command configurable
+
+Bug fixes
+---------
+* Fix building on NetBSD, Solaris
+* Restore time from driftfile with -s option if reading RTC failed
+
+Removed features
+----------------
+* Drop support for authentication with command key (run-time configuration
+  is now allowed only for local users that can access the Unix domain socket)
+
+New in version 2.1.1
+====================
+
+Bug fixes
+---------
+* Fix clock stepping by integer number of seconds on Linux
+
+New in version 2.1
+==================
+
+Enhancements
+------------
+* Add support for Mac OS X
+* Try to replace unreachable and falseticker servers/peers specified
+  by name like pool sources
+* Add leaponly option to smoothtime directive to allow synchronised
+  leap smear between multiple servers
+* Use specific reference ID when smoothing served time
+* Add smoothing command to report time smoothing status
+* Add smoothtime command to activate or reset time smoothing
+
+Bug fixes
+---------
+* Fix crash in source selection with preferred sources
+* Fix resetting of time smoothing
+* Include packet precision in peer dispersion
+* Fix crash in chronyc on invalid command syntax
+
+New in version 2.0
+==================
+
+Enhancements
+------------
+* Update to NTP version 4 (RFC 5905)
+* Add pool directive to specify pool of NTP servers
+* Add leapsecmode directive to select how to correct clock for leap second
+* Add smoothtime directive to smooth served time and enable leap smear
+* Add minsources directive to set required number of selectable sources
+* Add minsamples and maxsamples options for all sources
+* Add tempcomp configuration with list of points
+* Allow unlimited number of NTP sources, refclocks and keys
+* Allow unreachable sources to remain selected
+* Improve source selection
+* Handle offline sources as unreachable
+* Open NTP server port only when necessary (client access is allowed by
+  allow directive/command or peer/broadcast is configured)
+* Change default bindcmdaddress to loopback address
+* Change default maxdelay to 3 seconds
+* Change default stratumweight to 0.001
+* Update adjtimex synchronisation status
+* Use system headers for adjtimex
+* Check for memory allocation errors
+* Reduce memory usage
+* Add configure options to compile without NTP, cmdmon, refclock support
+* Extend makestep command to set automatic clock stepping
+
+Bug fixes
+---------
+* Add sanity checks for time and frequency offset
+* Don't report synchronised status during leap second
+* Don't combine reference clocks with close NTP sources
+* Fix accepting requests from configured sources
+* Fix initial fallback drift setting
+
+New in version 1.31.1
+=====================
+
+Security fixes
+--------------
+* Protect authenticated symmetric NTP associations against DoS attacks
+  (CVE-2015-1853)
+* Fix access configuration with subnet size indivisible by 4 (CVE-2015-1821)
+* Fix initialization of reply slots for authenticated commands (CVE-2015-1822)
+
+New in version 1.31
+===================
+
+Enhancements
+------------
+* Support operation in other NTP eras (next era begins in 2036),
+  NTP time is mapped to [-50, +86] years around build date by default
+* Restore time from driftfile with -s when RTC is missing/unsupported
+* Close connected client sockets when not waiting for reply
+* Use one client socket with random port when acquisitionport is 0
+* Use NTP packets instead of UDP echo for presend
+* Don't adjust polling interval when sending fails
+* Allow binding to addresses that don't exist yet
+* Ignore measurements around leap second
+* Improve detection of unexpected time jumps
+* Include example of logrotate configuration, systemd services and
+  NetworkManager dispatcher script
+
+Bug fixes
+---------
+* Reconnect client sockets for each request to follow changes
+  in network configuration automatically
+* Restart timer when polling interval is changed on reset
+
+New in version 1.30
+===================
+
+Enhancements
+------------
+* Add asynchronous name resolving with POSIX threads
+* Add PTP hardware clock (PHC) refclock driver
+* Add new generic clock driver to slew by adjusting frequency only
+  (without kernel PLL or adjtime) and use it on Linux
+* Add rtcautotrim directive to trim RTC automatically
+* Add hwclockfile directive to share RTC LOCAL/UTC setting with hwclock
+* Add maxslewrate directive to set maximum allowed slew rate
+* Add maxdispersion option for refclocks
+* Add -q/-Q options to set clock/print offset once and exit
+* Allow directives to be specified on chronyd command line
+* Replace frequency scaling in Linux driver with retaining of tick
+* Try to detect unexpected forward time jumps and reset state
+* Exit with non-zero code when maxchange limit is reached
+* Improve makestep to not start and stop slew unnecessarily
+* Change default corrtimeratio to 3.0 to improve frequency accuracy
+* Announce leap second only on last day of June and December
+* Use separate connected client sockets for each NTP server
+* Remove separate NTP implementation used for initstepslew
+* Limit maximum minpoll set by KoD RATE to default maxpoll
+* Don't send NTP requests with unknown key
+* Print warning when source is added with unknown key
+* Take leap second in PPS refclock from locked source
+* Make reading of RTC for initial trim more reliable
+* Don't create cmdmon sockets when cmdport is 0
+* Add configure option to set default user to drop root privileges
+* Add configure option to compile with debug messages
+* Print debug messages when -d is used more than once
+* Change format of messages written to terminal with -d
+* Write fatal messages also to stderr with -n
+* Use IP_RECVERR socket option in chronyc to not wait unnecessarily
+* Shorten default chronyc timeout for localhost
+* Change default hostname in chronyc from localhost to 127.0.0.1
+* Print error message on invalid syntax with all chronyc commands
+* Include simulation test suite using clknetsim
+
+Bug fixes
+---------
+* Fix crash when selecting with multiple preferred sources
+* Fix frequency calculation with large frequency offsets
+* Fix code writing drift and RTC files to compile correctly
+* Fix -4/-6 options in chronyc to not reset hostname set by -h
+* Fix refclock sample validation with sub-second polling interval
+* Set stratum correctly with non-PPS SOCK refclock and local stratum
+* Modify dispersion accounting in refclocks to prevent PPS getting
+  stuck with large dispersion and not accepting new samples
+
+New in version 1.29.1
+=====================
+
+Security fixes
+--------------
+* Modify chronyc protocol to prevent amplification attacks (CVE-2014-0021)
+  (incompatible with previous protocol version, chronyc supports both)
+
+New in version 1.29
+===================
+
+Security fixes
+--------------
+* Fix crash when processing crafted commands (CVE-2012-4502)
+  (possible with IP addresses allowed by cmdallow and localhost)
+* Don't send uninitialized data in SUBNETS_ACCESSED and CLIENT_ACCESSES
+  replies (CVE-2012-4503) (not used by chronyc)
+
+Other changes
+-------------
+* Drop support for SUBNETS_ACCESSED and CLIENT_ACCESSES commands
+
+New in version 1.28
+===================
+
+* Combine sources to improve accuracy
+* Make config and command parser strict
+* Add -a option to chronyc to authenticate automatically
+* Add -R option to ignore initstepslew and makestep directives
+* Add generatecommandkey, minsamples, maxsamples and user directives
+* Improve compatibility with NTPv1 and NTPv2 clients
+* Create sockets only in selected family with -4/-6 option
+* Treat address bind errors as non-fatal
+* Extend tracking log
+* Accept float values as initstepslew threshold
+* Allow hostnames in offline, online and burst commands
+* Fix and improve peer polling
+* Fix crash in config parsing with too many servers
+* Fix crash with duplicated initstepslew address
+* Fix delta calculation with extreme frequency offsets
+* Set local stratum correctly
+* Remove unnecessary adjtimex calls
+* Set paths in documentation by configure
+* Update chrony.spec
+
+New in version 1.27
+===================
+
+* Support for stronger keys via NSS or libtomcrypt library
+* Support reading leap second data from tz database
+* Support for precise clock stepping on Linux
+* Support for nanoseconds in SHM refclock
+* Make offset corrections smoother on Linux
+* Make transmit timestamps random below clock precision
+* Add corrtimeratio and maxchange directives
+* Extend tracking, sources and activity reports
+* Wait in foreground process until daemon is fully initialized
+* Fix crash with slow name resolving
+* Fix iburst with jittery sources
+* Fix offset stored in rtc data right after trimrtc
+* Fix crash and hang with RTC or manual samples
+* Don't use readonly adjtime on Linux kernels before 2.6.28 
+* Changed chronyc protocol, incompatible with older versions
+
+New in version 1.26
+===================
+
+* Add compatibility with Linux 3.0 and later
+* Use proper source address in NTP replies on multihomed IPv6 hosts
+* Accept NTP packets with versions 4, 3 and 2
+* Cope with unexpected backward time jumps
+* Don't reset kernel frequency on start without drift file
+* Retry on permanent DNS error by default
+* Add waitsync command
+
+New in version 1.25
+===================
+
+* Improve accuracy with NTP sources
+* Improve accuracy with reference clocks
+* Improve polling interval adjustment
+* Improve stability with temporary asymmetric delays
+* Improve source selection
+* Improve initial synchronisation
+* Add delayed server name resolving
+* Add temperature compensation
+* Add nanosecond slewing to Linux driver
+* Add fallback drifts
+* Add iburst, minstratum, maxdelaydevratio, polltarget,
+  prefer, noselect options
+* Add rtcsync directive to enable Linux 11-minute mode
+* Add reselectdist, stratumweight, logbanner, maxclockerror,
+  include directives
+* Add -n option to not detach daemon from terminal
+* Fix pidfile directive
+* Fix name resolving with disabled IPv6 support
+* Fix reloading sample histories with reference clocks
+* Fix crash with auto_offline option
+* Fix online command on auto_offline sources
+* Fix file descriptor leaks
+* Increase burst polling interval and stop on KoD RATE
+* Set maxupdateskew to 1000 ppm by default
+* Require password for clients command
+* Update drift file at most once per hour
+* Use system headers for Linux RTC support
+* Reduce default chronyc timeout and make it configurable
+* Avoid large values in chronyc sources and sourcestats output
+* Add reselect command to force reselecting best source
+* Add -m option to allow multiple commands on command line
+
+New in version 1.24
+===================
+
+Security fixes
+--------------
+* Don't reply to invalid cmdmon packets (CVE-2010-0292)
+* Limit client log memory size (CVE-2010-0293)
+* Limit rate of syslog messages (CVE-2010-0294)
+
+Bug fixes/Enhancements
+----------------------
+* Support for reference clocks (SHM, SOCK, PPS drivers)
+* IPv6 support
+* Linux capabilities support (to drop root privileges)
+* Memory locking support on Linux
+* Real-time scheduler support on Linux
+* Leap second support on Linux
+* Support for editline library
+* Support for new Linux readonly adjtime
+* NTP client support for KoD RATE
+* Read kernel timestamps for received NTP packets
+* Reply to NTP requests with correct address on multihomed hosts
+* Retry name resolving after temporary failure
+* Fix makestep command, make it available on all systems
+* Add makestep directive for automatic clock stepping
+* Don't require _bigadj kernel symbol on NetBSD
+* Avoid blocking read in Linux RTC driver
+* Support for Linux on S/390 and PowerPC
+* Fix various bugs on 64-bit systems
+* Fix valgrind errors and compiler warnings
+* Improve configure to support common options and variables
+* Improve status checking and printing in chronyc
+* Return non-zero exit code on errors in chronyc
+* Reduce request timeout in chronyc
+* Print estimated offset in sourcestats
+* Changed chronyc protocol, incompatible with older versions
+
+New in version 1.23
+===================
+
+* Support for MIPS, x86_64, sparc, alpha, arm, FreeBSD
+* Fix serious sign-extension error in handling IP addresses
+* RTC support can be excluded at compile time
+* Make sources gcc-4 compatible
+* Fix various compiler warnings
+* Handle fluctuations in peer distance better.
+* Fixed handling of stratum zero.
+* Fix various problems for 64-bit systems
+* Flush chronyc output streams after each command, to allow it to be driven
+  through pipes
+* Manpage improvements
+
+Version 1.22
+============
+
+This release number was claimed by a release that Mandriva made to patch
+important bugs in 1.21.  The official numbering has jumped to 1.23 as a
+consequence.
+
+New in version 1.21
+===================
+
+* Don't include Linux kernel header files any longer : allows chrony to compile
+  on recent distros.
+* Stop trying to use RTC if continuous streams of error messages would occur
+  (Linux with HPET).
+
+New in version 1.20
+===================
+
+* Many small tidy-ups and security improvements
+* Improve documentation (RTC support in post 2.0 kernels)
+* Remove trailing \n from syslog messages
+* Syslog messages now include IP and port number when packet cannot be sent.
+* Added the "acquisitionport" directive.  (Kalle Olavi Niemitalo)
+* Use uname(2) instead of /proc/version to get kernel version.
+* Merge support for Linux on Alpha
+* Merge support for 64bit architectures
+* Don't link -lm if it's not needed
+* Fix Solaris build (broken by 64bit change)
+* Add detection of Linux 2.5
+* Allow arbitrary value of HZ in Linux kernel
+* Fix for chrony.spec on SuSE (Paul Elliot)
+* Fix handling of initstepslew if no servers are listed (John Hasler)
+* Fix install rule in Makefile if chronyd is in use (Juliusz Chroboczek)
+* Replace sprintf by snprintf to remove risk of buffer overrun (John Hasler)
+* Add --help to configure script
+
+New in version 1.19
+===================
+
+* Auto-detect kernel's timer interrupt rate (so-called 'HZ') when chronyd
+  starts instead of relying on compiled-in value.
+* Fix 2 bugs in function that creates the directory for the log and dump files.
+* Amended webpage URL and contact details.
+* Generate more informative syslog messages before exiting on failed
+  assertions.
+* Fix bugs in clamping code for the tick value used when slewing a large
+  offset.
+* Don't chown files to root during install (should be pointless, and makes RPM
+  building awkward as ordinary user.)
+* Include chrony.spec file for building RPMs
+
+New in version 1.18
+===================
+* Amend homepage and mailing list information to chrony.sunsite.dk
+* Delete pidfile on exit from chronyd.
+* Improvements to readline interface to chronyc
+* Only generate syslog message when synchronisation is initially lost (instead
+  of on every failed synchronisation attempt)
+* Use double fork approach when initialising daemon.
+* More things in contrib directory.
+* New options to help package builders: --infodir/--mandir for configure, and
+  DESTDIR=xxx for make.  (See section 2.2 of chrony.txt for details).
+* Changed the wording of the messages generated by mailonchange and logchange
+  directives.
+
+New in version 1.17
+===================
+* Port to NetBSD
+* Configuration supports Linux on PPC
+* Fix compilation warnings
+* Several documentation improvements
+* Bundled manpages (taken from the 'missing manpages project')
+* Cope with lack of bzero function for Solaris 2.3 systems
+* Store chronyd's pid in a file (default /var/run/chronyd.pid) and check if
+  chronyd may already be running when starting up.  New pidfile directive in
+  configuration file.
+* Any size subnet is now allowed in allow and deny commands.  (Example:
+  6.7.8/20 or 6.7.8.x/20 (any x) mean a 20 bit subnet).
+* The environment variables CC and CFLAGS passed to configure can now be used
+  to select the compiler and optimisation/debug options to use
+* Write syslog messages when chronyd loses synchronisation.
+* Print GPL text when chronyc is run.
+* Add NTP broadcast server capability (new broadcast directive).
+* Add 'auto_offline' option to server/peer (conf file) or add server/peer (via
+  chronyc).
+* Add 'activity' command to chronyc, to report how many servers/peers are
+  currently online/offline.
+* Fix long-standing bug with how the system time quantum was calculated.
+* Include support for systems with HZ!=100 (HZ is the timer interrupt
+  frequency).
+* Include example chrony.conf and chrony.keys files (examples subdirectory).
+* Include support for readline in chronyc.
+
+New in version 1.16.1
+=====================
+* Fix compilation problem on Linux 2.4.13 (spinlock.h / spinlock_t)
+
+New in version 1.16
+===================
+* More informative captions for 'sources' and 'sourcestats' commands in chronyc
+  (use 'sources -v' and 'sourcestats -v' to get them).
+* Correct behaviour for Solaris versions>=2.6 (dosynctodr not required on these
+  versions.)
+* Remove some compiler warnings (Solaris)
+* If last line of keys file doesn't have end-of-line, don't truncate final
+  character of that key.
+* Change timestamp format used in logfiles to make it fully numeric (to aid
+  importing data into spreadsheets etc)
+* Minor documentation updates and improvements.
+
+New in version 1.15
+===================
+* Add contributed change to 'configure' to support Solaris 2.8 on x86
+* Workaround for assertion failure that arises if two received packets occur
+  close together. (Still need to find out why this happens at all.)
+* Hopefully fix problem where fast slewing was incompatible with machines
+  that have a large background drift rate (=> tick value went out of range
+  for adjtimex() on Linux.)
+* Fix rtc_linux.c compile problems with 2.4.x kernel include files.
+* Include support for RTC device not being at /dev/rtc (new rtcdevice directive
+  in configuration file).
+* Include support for restricting network interfaces for commands (new
+  bindcmdaddress directive in configuration file)
+* Fix potential linking fault in pktlength.c (use of CROAK macro replaced by
+  normal assert).
+* Add some material on bug reporting + contributing to the chrony.texi file
+* Made the chrony.texi file "Vim6-friendly" (removed xrefs on @node lines,
+  added folding markers to chapters + sections.)
+* Switched over to GPL for the licence
+
+New in version 1.14
+===================
+* Fix compilation for certain other Linux distributions (including Mandrake
+  7.1)
+
+New in version 1.13
+===================
+* Fixed compilation problems on Redhat/SuSE installations with recent 2.2.x
+  kernels.
+* Minor tidy-ups and documentation enhancements.
+* Add support for Linux 2.4 kernels
+
+New in version 1.12
+===================
+
+* Trial fix for long-standing bug in Linux RTC estimator when system time is
+  slewed.
+* Fix bug in chronyc if -h is specified without a hostname
+* Fixes to logging various error conditions when operating in daemon mode.
+* More stuff under contrib/
+* Changes to README file (e.g. about the new chrony-users mailing list)
+
+New in version 1.11a
+====================
+
+* Minor changes to contact details
+* Minor changes to installation details (chrony subdirectory under doc/)
+
+New in version 1.11
+===================
+
+* Improve robustness of installation procedure
+* Tidy up documenation and contact details
+* Distribute manual as .txt rather than as .ps
+* Add -n option to chronyc to work with numeric IP addresses rather than
+  names.
+* Add material in contrib subdirectory
+* Improve robustness of handling drift file and RTC coefficients file
+* Improve robustness of regression algorithm
+
+New in version 1.1
+==================
+
+Bug fixes
+---------
+
+* Made linear regression more resistant to rounding errors (old one
+  occasionally generated negative variances which made everything go
+  haywire).  Trap infinite or 'not-a-number' values being used to
+  alter system clock to increase robustness further.
+
+Other changes/Enhancements
+--------------------------
+
+* Support for Linux 2.1 and 2.2 kernels
+
+* New command 'makestep' in chronyc to immediately jump the system
+  time to match the NTP estimated time (Linux only) - a response to
+  systems booting an hour wrong after summertime/wintertime changes,
+  due to RTCs running on local time.  Needs extending to Sun driver
+  files too.
+
+* New directives 'logchange' and 'mailonchange' to log to syslog or
+  email to a specific address respectively if chronyd detects a clock
+  offset exceeding a defined threshold.
+
+* Added capability to log all client/peer NTP accesses and command
+  accesses (can be turned off with conf file directive 'noclientlog').
+  Added 'clients' command to chronyc to display this data.
+
+* Improved manual mode to use robust regression rather than 2 point
+  fit.
+
+* Added 'manual list' and 'manual delete' commands to chronyc to
+  allow display of entered timestamps and discretionary deletion of
+  outliers.
+
+* If host goes unsynchronised the dummy IP address 0.0.0.0 is detected
+  to avoid attempting a reverse name lookup (to stop dial on demand IP
+  links from being started)
+
+* Changed chronyc/chronyd protocol so messages are now all variable
+  length.  Saves on network bandwidth particularly for large replies
+  from chronyd to chronyc (to support the clients command).
+
+* Added bindaddress directive to configuration file, to give
+  additional control over limiting which hosts can access the local
+  server.
+
+* Groundwork done for a port to Windows NT to compile with Cygwin
+  toolkit.  chronyc works (to monitor another host).  sys_winnt.c
+  needs finishing to use NT clock control API.  Program structure
+  needs adapting to use Windows NT service functions, so it can be
+  started at boot time.  Hopefully a Windows NT / Cygwin guru with
+  some spare time can take this port over :-)
+
+New in version 1.02
+===================
+
+Bug fixes
+---------
+
+* Fix error messages in chronyc if daemon is not reachable.
+
+* Fix config file problem for 'allow all' and 'deny all' without a
+  trailing machine address.
+
+* Remove fatal failed assertion if command socket cannot be read from
+  in daemon.
+
+* Rewrote timezone handling for Linux real time clock, following
+  various reported problems related to daylight saving.
+
+Other changes/Enhancements
+--------------------------
+
+* Configure script recognizes BSD/386 and uses SunOS 4.1 driver for
+  it.
+
+* Log files now print date as day-month-year rather than as a day
+  number.  Milliseconds removed from timestamps of logged data.
+  Banners included in file to give meanings of columns.
+
+* Only do 1 initial step (followed by a trimming slew) when
+  initialising from RTC on Linux (previously did 2 steps).
+
+New in version 1.01
+===================
+
+Bug fixes
+---------
+
+* Handle timezone of RTC correctly with respect to daylight saving
+  time
+
+* Syntax check the chronyc 'local' command properly
+
+* Fixed assertion failed fault in median finder (used by RTC
+  regression fitting)
+
+Other changes/Enhancements
+--------------------------
+
+* Log selection of new NTP reference source to syslog.
+
+* Don't zero-pad IP address fields
+
+* Add new command to chronyc to allow logfiles to be cycled.
+
+* Extend allow/deny directive syntax in configuration file to so
+  directive can apply to all hosts on the Internet.
+
+* Tidy up printout of timestamps to make it clear they are in UTC
+
+* Make 'configure' check the processor type as well as the operating
+  system.
diff --git a/README b/README
new file mode 100644
index 0000000..00214a5
--- /dev/null
+++ b/README
@@ -0,0 +1,160 @@
+This is the README for chrony.
+
+What is chrony?
+===============
+
+chrony is a versatile implementation of the Network Time Protocol (NTP).
+It can synchronise the system clock with NTP servers, reference clocks
+(e.g. GPS receiver), and manual input using wristwatch and keyboard.
+It can also operate as an NTPv4 (RFC 5905) server and peer to provide
+a time service to other computers in the network.
+
+It is designed to perform well in a wide range of conditions, including
+intermittent network connections, heavily congested networks, changing
+temperatures (ordinary computer clocks are sensitive to temperature),
+and systems that do not run continuosly, or run on a virtual machine.
+
+Typical accuracy between two machines synchronised over the Internet is
+within a few milliseconds; on a LAN, accuracy is typically in tens of
+microseconds.  With hardware timestamping, or a hardware reference clock,
+sub-microsecond accuracy may be possible.
+
+Two programs are included in chrony, chronyd is a daemon that can be
+started at boot time and chronyc is a command-line interface program
+which can be used to monitor chronyd's performance and to change various
+operating parameters whilst it is running.
+
+What will chrony run on?
+========================
+
+The software is known to work on Linux, FreeBSD, NetBSD, macOS and
+illumos.  Closely related systems may work too.  Any other system will
+likely require a porting exercise.
+
+How do I set it up?
+===================
+
+The file INSTALL gives instructions.  On supported systems the
+compilation process should be automatic.  You will need a C compiler,
+e.g. gcc or clang.
+
+What documentation is there?
+============================
+
+The distribution includes manual pages and a document containing
+Frequently Asked Questions (FAQ).
+
+The documentation is also available on the chrony web pages, accessible
+through the URL 
+
+    https://chrony.tuxfamily.org/
+
+Where are new versions announced?
+=================================
+
+There is a low volume mailing list where new versions and other
+important news relating to chrony are announced.  You can join this list
+by sending mail with the subject "subscribe" to
+
+chrony-announce-request@chrony.tuxfamily.org
+
+How can I get support for chrony?
+=================================
+
+There are two other mailing lists relating to chrony.  chrony-users is a
+discussion list for users, e.g. for questions about chrony configuration
+and bug reports.  chrony-dev is a more technical list for developers,
+e.g. for submitting patches and discussing how new features should be
+implemented.  To subscribe to either of these lists, send a message with
+the subject "subscribe" to
+
+chrony-users-request@chrony.tuxfamily.org
+or
+chrony-dev-request@chrony.tuxfamily.org
+
+as applicable.
+
+License
+=======
+
+chrony is distributed under the GNU General Public License version 2.
+
+Authors
+=======
+
+Richard P. Curnow <rc@rc0.org.uk>
+Miroslav Lichvar <mlichvar@redhat.com>
+
+Acknowledgements
+================
+
+In writing the chronyd program, extensive use has been made of the NTPv3 (RFC
+1305) and NTPv4 (RFC 5905) specification.  The source code of the xntpd/ntpd
+implementation written by Dennis Fergusson, Lars Mathiesen, David Mills, and
+others has been used to check the details of the protocol.
+
+The following people have provided patches and other major contributions
+to chrony:
+
+Lonnie Abelbeck <lonnie@abelbeck.com>
+Benny Lyne Amorsen <benny@amorsen.dk>
+Andrew Bishop <amb@gedanken.demon.co.uk>
+Vincent Blut <vincent.debian@free.fr>
+Stephan I. Boettcher <stephan@nevis1.columbia.edu>
+David Bohman <debohman@gmail.com>
+Goswin Brederlow <brederlo@informatik.uni-tuebingen.de>
+Leigh Brown <leigh@solinno.co.uk>
+Erik Bryer <ebryer@spots.ab.ca>
+Jonathan Cameron <jic23@cam.ac.uk>
+Bryan Christianson <bryan@whatroute.net>
+Juliusz Chroboczek <jch@pps.jussieu.fr>
+Kamil Dudka <kdudka@redhat.com>
+Christian Ehrhardt <christian.ehrhardt@canonical.com>
+Paul Elliott <pelliott@io.com>
+Robert Fairley <rfairley@redhat.com>
+Stefan R. Filipek <srfilipek@gmail.com>
+Mike Fleetwood <mike@rockover.demon.co.uk>
+Alexander Gretencord <arutha@gmx.de>
+Andrew Griffiths <agriffit@redhat.com>
+Walter Haidinger <walter.haidinger@gmx.at>
+Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de>
+John Hasler <john@dhh.gt.org>
+Tjalling Hattink <t.hattink@fugro.nl>
+Liam Hatton <me@liamhatton.com>
+Jachym Holecek <jakym@volny.cz>
+Håkan Johansson <f96hajo@chalmers.se>
+Jim Knoble <jmknoble@pobox.com>
+Antti Jrvinen <costello@iki.fi>
+Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+Eric Lammerts <eric@lammerts.org>
+Stefan Lucke <stefan@lucke.in-berlin.de>
+Victor Lum <viclum@vanu.com>
+Kevin Lyda <kevin@ie.suberic.net>
+Paul Menzel <paulepanter@users.sourceforge.net>
+Vladimir Michl <vladimir.michl@seznam.cz>
+Victor Moroz <vim@prv.adlum.ru>
+Kalle Olavi Niemitalo  <tosi@stekt.oulu.fi>
+Frank Otto <sandwichmacher@web.de>
+Denny Page <dennypage@me.com>
+Chris Perl <cperl@janestreet.com>
+Gautier PHILIPPON <gautier.philippon@ensimag.grenoble-inp.fr>
+Andreas Piesk <apiesk@virbus.de>
+Baruch Siach <baruch@tkos.co.il>
+Foster Snowhill <forst@forstwoof.ru>
+Andreas Steinmetz <ast@domdv.de>
+NAKAMURA Takumi <takumi@ps.sakura.ne.jp>
+Timo Teras <timo.teras@iki.fi>
+Bill Unruh <unruh@physics.ubc.ca>
+Stephen Wadeley <swadeley@redhat.com>
+Bernhard Weiss <lisnablagh@web.de>
+Wolfgang Weisselberg <weissel@netcologne.de>
+Bernhard M. Wiedemann <bwiedemann@suse.de>
+Joachim Wiedorn <ad_debian@joonet.de>
+Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
+Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
+Michael Witten <mfwitten@gmail.com>
+Doug Woodward <dougw@whistler.com>
+Thomas Zajic <zlatko@zlatko.fdns.net>
+
+Many other people have contributed bug reports and suggestions.  We are sorry
+we cannot identify all of you individually.
diff --git a/addressing.h b/addressing.h
new file mode 100644
index 0000000..3e311fa
--- /dev/null
+++ b/addressing.h
@@ -0,0 +1,67 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Types used for addressing sources etc
+  */
+
+#ifndef GOT_ADDRESSING_H
+#define GOT_ADDRESSING_H
+
+#include "sysincl.h"
+
+/* This type is used to represent an IPv4 address or IPv6 address.
+   Addresses which are not resolved yet can be represented with an ID.
+   All parts are in HOST order, NOT network order. */
+
+#define IPADDR_UNSPEC 0
+#define IPADDR_INET4 1
+#define IPADDR_INET6 2
+#define IPADDR_ID 3
+
+typedef struct {
+  union { 
+    uint32_t in4;
+    uint8_t in6[16];
+    uint32_t id;
+  } addr;
+  uint16_t family;
+  uint16_t _pad;
+} IPAddr;
+
+typedef struct {
+  IPAddr ip_addr;
+  uint16_t port;
+} IPSockAddr;
+
+typedef IPSockAddr NTP_Remote_Address;
+
+#define INVALID_IF_INDEX -1
+
+typedef struct {
+  IPAddr ip_addr;
+  int if_index;
+  int sock_fd;
+} NTP_Local_Address;
+
+#endif /* GOT_ADDRESSING_H */
+
diff --git a/addrfilt.c b/addrfilt.c
new file mode 100644
index 0000000..6208b46
--- /dev/null
+++ b/addrfilt.c
@@ -0,0 +1,405 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997,1998,1999,2000,2001,2002,2005
+ * Copyright (C) Miroslav Lichvar  2009, 2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module provides a set of routines for checking IP addresses
+  against a set of rules and deciding whether they are allowed or
+  disallowed.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "addrfilt.h"
+#include "memory.h"
+
+/* Define the number of bits which are stripped off per level of
+   indirection in the tables */
+#define NBITS 4
+
+/* Define the table size */
+#define TABLE_SIZE (1UL<<NBITS)
+
+typedef enum {DENY, ALLOW, AS_PARENT} State;
+
+typedef struct _TableNode {
+  State state;
+  struct _TableNode *extended;
+} TableNode;
+
+struct ADF_AuthTableInst {
+  TableNode base4;      /* IPv4 node */
+  TableNode base6;      /* IPv6 node */
+};
+
+/* ================================================== */
+
+static void
+split_ip6(IPAddr *ip, uint32_t *dst)
+{
+  int i;
+
+  for (i = 0; i < 4; i++)
+    dst[i] = (uint32_t)ip->addr.in6[i * 4 + 0] << 24 |
+             ip->addr.in6[i * 4 + 1] << 16 |
+             ip->addr.in6[i * 4 + 2] << 8 |
+             ip->addr.in6[i * 4 + 3];
+}
+
+/* ================================================== */
+
+inline static uint32_t
+get_subnet(uint32_t *addr, unsigned int where)
+{
+  int off;
+
+  off = where / 32;
+  where %= 32;
+
+  return (addr[off] >> (32 - NBITS - where)) & ((1UL << NBITS) - 1);
+}
+
+/* ================================================== */
+
+ADF_AuthTable
+ADF_CreateTable(void)
+{
+  ADF_AuthTable result;
+  result = MallocNew(struct ADF_AuthTableInst);
+
+  /* Default is that nothing is allowed */
+  result->base4.state = DENY;
+  result->base4.extended = NULL;
+  result->base6.state = DENY;
+  result->base6.extended = NULL;
+
+  return result;
+}
+
+/* ================================================== */
+/* This function deletes all definitions of child nodes, in effect
+   pruning a whole subnet definition back to a single parent
+   record. */
+static void
+close_node(TableNode *node)
+{
+  int i;
+  TableNode *child_node;
+
+  if (node->extended != NULL) {
+    for (i=0; i<TABLE_SIZE; i++) {
+      child_node = &(node->extended[i]);
+      close_node(child_node);
+    }
+    Free(node->extended);
+    node->extended = NULL;
+  }
+}
+
+
+/* ================================================== */
+/* Allocate the extension field in a node, and set all the children's
+   states to default to that of the node being extended */
+
+static void
+open_node(TableNode *node)
+{
+  int i;
+  TableNode *child_node;
+
+  if (node->extended == NULL) {
+
+    node->extended = MallocArray(struct _TableNode, TABLE_SIZE);
+
+    for (i=0; i<TABLE_SIZE; i++) {
+      child_node = &(node->extended[i]);
+      child_node->state = AS_PARENT;
+      child_node->extended = NULL;
+    }
+  }
+}
+
+/* ================================================== */
+
+static ADF_Status
+set_subnet(TableNode *start_node,
+           uint32_t *ip,
+           int ip_len,
+           int subnet_bits,
+           State new_state,
+           int delete_children)
+{
+  int bits_to_go, bits_consumed;
+  uint32_t subnet;
+  TableNode *node;
+
+  bits_consumed = 0;
+  bits_to_go = subnet_bits;
+  node = start_node;
+
+  if ((subnet_bits < 0) ||
+      (subnet_bits > 32 * ip_len)) {
+
+    return ADF_BADSUBNET;
+
+  } else {
+
+    if ((bits_to_go & (NBITS-1)) == 0) {
+    
+      while (bits_to_go > 0) {
+        subnet = get_subnet(ip, bits_consumed);
+        if (!(node->extended)) {
+          open_node(node);
+        }
+        node = &(node->extended[subnet]);
+        bits_to_go -= NBITS;
+        bits_consumed += NBITS;
+      }
+
+      if (delete_children) {
+        close_node(node);
+      }
+      node->state = new_state;
+
+    } else { /* Have to set multiple entries */
+      int N, i, j;
+      TableNode *this_node;
+
+      while (bits_to_go >= NBITS) {
+        subnet = get_subnet(ip, bits_consumed);
+        if (!(node->extended)) {
+          open_node(node);
+        }
+        node = &(node->extended[subnet]);
+        bits_to_go -= NBITS;
+        bits_consumed += NBITS;
+      }
+
+      /* How many subnet entries to set : 1->8, 2->4, 3->2 */
+      N = 1 << (NBITS-bits_to_go);
+
+      subnet = get_subnet(ip, bits_consumed) & ~(N - 1);
+      assert(subnet + N <= TABLE_SIZE);
+
+      if (!(node->extended)) {
+        open_node(node);
+      }
+      
+      for (i=subnet, j=0; j<N; i++, j++) {
+        this_node = &(node->extended[i]);
+        if (delete_children) {
+          close_node(this_node);
+        }
+        this_node->state = new_state;
+      }
+    }
+    
+    return ADF_SUCCESS;
+  }
+  
+}
+
+/* ================================================== */
+
+static ADF_Status
+set_subnet_(ADF_AuthTable table,
+           IPAddr *ip_addr,
+           int subnet_bits,
+           State new_state,
+           int delete_children)
+{
+  uint32_t ip6[4];
+
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+      return set_subnet(&table->base4, &ip_addr->addr.in4, 1, subnet_bits, new_state, delete_children);
+    case IPADDR_INET6:
+      split_ip6(ip_addr, ip6);
+      return set_subnet(&table->base6, ip6, 4, subnet_bits, new_state, delete_children);
+    case IPADDR_UNSPEC:
+      /* Apply to both, subnet_bits has to be 0 */
+      if (subnet_bits != 0)
+        return ADF_BADSUBNET;
+      memset(ip6, 0, sizeof (ip6));
+      if (set_subnet(&table->base4, ip6, 1, 0, new_state, delete_children) == ADF_SUCCESS &&
+          set_subnet(&table->base6, ip6, 4, 0, new_state, delete_children) == ADF_SUCCESS)
+        return ADF_SUCCESS;
+      break;
+    default:
+      break;
+  }
+
+  return ADF_BADSUBNET;
+}
+
+ADF_Status
+ADF_Allow(ADF_AuthTable table,
+          IPAddr *ip,
+          int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, ALLOW, 0);
+}
+
+/* ================================================== */
+
+
+ADF_Status
+ADF_AllowAll(ADF_AuthTable table,
+             IPAddr *ip,
+             int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, ALLOW, 1);
+}
+
+/* ================================================== */
+
+ADF_Status
+ADF_Deny(ADF_AuthTable table,
+         IPAddr *ip,
+         int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, DENY, 0);
+}
+
+/* ================================================== */
+
+ADF_Status
+ADF_DenyAll(ADF_AuthTable table,
+            IPAddr *ip,
+            int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, DENY, 1);
+}
+
+/* ================================================== */
+
+void
+ADF_DestroyTable(ADF_AuthTable table)
+{
+  close_node(&table->base4);
+  close_node(&table->base6);
+  Free(table);
+}
+
+/* ================================================== */
+
+static int
+check_ip_in_node(TableNode *start_node, uint32_t *ip)
+{
+  uint32_t subnet;
+  int bits_consumed = 0;
+  int result = 0;
+  int finished = 0;
+  TableNode *node;
+  State state=DENY;
+
+  node = start_node;
+
+  do {
+    if (node->state != AS_PARENT) {
+      state = node->state;
+    }
+    if (node->extended) {
+      subnet = get_subnet(ip, bits_consumed);
+      node = &(node->extended[subnet]);
+      bits_consumed += NBITS;
+    } else {
+      /* Make decision on this node */
+      finished = 1;
+    }
+  } while (!finished);
+
+  switch (state) {
+    case ALLOW:
+      result = 1;
+      break;
+    case DENY:
+      result = 0;
+      break;
+    case AS_PARENT:
+      assert(0);
+      break;
+  }
+
+  return result;
+}
+
+
+/* ================================================== */
+
+int
+ADF_IsAllowed(ADF_AuthTable table,
+              IPAddr *ip_addr)
+{
+  uint32_t ip6[4];
+
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+      return check_ip_in_node(&table->base4, &ip_addr->addr.in4);
+    case IPADDR_INET6:
+      split_ip6(ip_addr, ip6);
+      return check_ip_in_node(&table->base6, ip6);
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+is_any_allowed(TableNode *node, State parent)
+{
+  State state;
+  int i;
+
+  state = node->state != AS_PARENT ? node->state : parent;
+  assert(state != AS_PARENT);
+
+  if (node->extended) {
+    for (i = 0; i < TABLE_SIZE; i++) {
+      if (is_any_allowed(&node->extended[i], state))
+        return 1;
+    }
+  } else if (state == ALLOW) {
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+ADF_IsAnyAllowed(ADF_AuthTable table, int family)
+{
+  switch (family) {
+    case IPADDR_INET4:
+      return is_any_allowed(&table->base4, AS_PARENT);
+    case IPADDR_INET6:
+      return is_any_allowed(&table->base6, AS_PARENT);
+    default:
+      return 0;
+  }
+}
diff --git a/addrfilt.h b/addrfilt.h
new file mode 100644
index 0000000..b8c131f
--- /dev/null
+++ b/addrfilt.h
@@ -0,0 +1,80 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module for providing an authorisation filter on IP addresses
+  */
+
+#ifndef GOT_ADDRFILT_H
+#define GOT_ADDRFILT_H
+
+#include "addressing.h"
+
+typedef struct ADF_AuthTableInst *ADF_AuthTable;
+
+typedef enum {
+  ADF_SUCCESS,
+  ADF_BADSUBNET
+} ADF_Status;
+  
+
+/* Create a new table.  The default rule is deny for everything */
+extern ADF_AuthTable ADF_CreateTable(void);
+
+/* Allow anything in the supplied subnet, EXCEPT for any more specific
+   subnets that are already defined */
+extern ADF_Status ADF_Allow(ADF_AuthTable table,
+                            IPAddr *ip,
+                            int subnet_bits);
+
+/* Allow anything in the supplied subnet, overwriting existing
+   definitions for any more specific subnets */
+extern ADF_Status ADF_AllowAll(ADF_AuthTable table,
+                               IPAddr *ip,
+                               int subnet_bits);
+
+/* Deny anything in the supplied subnet, EXCEPT for any more specific
+   subnets that are already defined */
+extern ADF_Status ADF_Deny(ADF_AuthTable table,
+                           IPAddr *ip,
+                           int subnet_bits);
+
+/* Deny anything in the supplied subnet, overwriting existing
+   definitions for any more specific subnets */
+extern ADF_Status ADF_DenyAll(ADF_AuthTable table,
+                              IPAddr *ip,
+                              int subnet_bits);
+
+/* Clear up the table */
+extern void ADF_DestroyTable(ADF_AuthTable table);
+
+/* Check whether a given IP address is allowed by the rules in 
+   the table */
+extern int ADF_IsAllowed(ADF_AuthTable table,
+                         IPAddr *ip);
+
+/* Check if at least one address from a given family is allowed by
+   the rules in the table */
+extern int ADF_IsAnyAllowed(ADF_AuthTable table,
+                            int family);
+
+#endif /* GOT_ADDRFILT_H */
diff --git a/array.c b/array.c
new file mode 100644
index 0000000..d70cff9
--- /dev/null
+++ b/array.c
@@ -0,0 +1,130 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions implementing an array with automatic memory allocation.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "memory.h"
+
+struct ARR_Instance_Record {
+  void *data;
+  unsigned int elem_size;
+  unsigned int used;
+  unsigned int allocated;
+};
+
+ARR_Instance
+ARR_CreateInstance(unsigned int elem_size)
+{
+  ARR_Instance array;
+
+  assert(elem_size > 0);
+
+  array = MallocNew(struct ARR_Instance_Record);
+
+  array->data = NULL;
+  array->elem_size = elem_size;
+  array->used = 0;
+  array->allocated = 0;
+
+  return array;
+}
+
+void
+ARR_DestroyInstance(ARR_Instance array)
+{
+  Free(array->data);
+  Free(array);
+}
+
+static void
+realloc_array(ARR_Instance array, unsigned int min_size)
+{
+  assert(min_size <= 2 * min_size);
+  if (array->allocated >= min_size && array->allocated <= 2 * min_size)
+    return;
+
+  if (array->allocated < min_size) {
+    while (array->allocated < min_size)
+      array->allocated = array->allocated ? 2 * array->allocated : 1;
+  } else {
+    array->allocated = min_size;
+  }
+
+  array->data = Realloc2(array->data, array->allocated, array->elem_size);
+}
+
+void *
+ARR_GetNewElement(ARR_Instance array)
+{
+  array->used++;
+  realloc_array(array, array->used);
+  return ARR_GetElement(array, array->used - 1);
+}
+
+void *
+ARR_GetElement(ARR_Instance array, unsigned int index)
+{
+  assert(index < array->used);
+  return (void *)((char *)array->data + (size_t)index * array->elem_size);
+}
+
+void *
+ARR_GetElements(ARR_Instance array)
+{
+  /* Return a non-NULL pointer when the array has zero size */
+  if (!array->data) {
+    assert(!array->used);
+    return array;
+  }
+
+  return array->data;
+}
+
+void
+ARR_AppendElement(ARR_Instance array, void *element)
+{
+  void *e;
+
+  e = ARR_GetNewElement(array);
+  memcpy(e, element, array->elem_size);
+}
+
+void
+ARR_SetSize(ARR_Instance array, unsigned int size)
+{
+  realloc_array(array, size);
+  array->used = size;
+}
+
+unsigned int
+ARR_GetSize(ARR_Instance array)
+{
+  return array->used;
+}
diff --git a/array.h b/array.h
new file mode 100644
index 0000000..c812e84
--- /dev/null
+++ b/array.h
@@ -0,0 +1,56 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for array functions.
+  */
+
+#ifndef GOT_ARRAY_H
+#define GOT_ARRAY_H
+
+typedef struct ARR_Instance_Record *ARR_Instance;
+
+/* Create a new array with given element size */
+extern ARR_Instance ARR_CreateInstance(unsigned int elem_size);
+
+/* Destroy the array */
+extern void ARR_DestroyInstance(ARR_Instance array);
+
+/* Return pointer to a new element added to the end of the array */
+extern void *ARR_GetNewElement(ARR_Instance array);
+
+/* Return element with given index */
+extern void *ARR_GetElement(ARR_Instance array, unsigned int index);
+
+/* Return pointer to the internal array of elements */
+extern void *ARR_GetElements(ARR_Instance array);
+
+/* Add a new element to the end of the array */
+extern void ARR_AppendElement(ARR_Instance array, void *element);
+
+/* Set the size of the array */
+extern void ARR_SetSize(ARR_Instance array, unsigned int size);
+
+/* Return current size of the array */
+extern unsigned int ARR_GetSize(ARR_Instance array);
+
+#endif
diff --git a/candm.h b/candm.h
new file mode 100644
index 0000000..3071828
--- /dev/null
+++ b/candm.h
@@ -0,0 +1,824 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Definitions for the network protocol used for command and monitoring
+  of the timeserver.
+
+  */
+
+#ifndef GOT_CANDM_H
+#define GOT_CANDM_H
+
+#include "sysincl.h"
+#include "addressing.h"
+
+/* This is the default port to use for CANDM, if no alternative is
+   defined */
+#define DEFAULT_CANDM_PORT 323
+
+/* Request codes */
+#define REQ_NULL 0
+#define REQ_ONLINE 1
+#define REQ_OFFLINE 2
+#define REQ_BURST 3
+#define REQ_MODIFY_MINPOLL 4
+#define REQ_MODIFY_MAXPOLL 5
+#define REQ_DUMP 6
+#define REQ_MODIFY_MAXDELAY 7
+#define REQ_MODIFY_MAXDELAYRATIO 8
+#define REQ_MODIFY_MAXUPDATESKEW 9
+#define REQ_LOGON 10
+#define REQ_SETTIME 11
+#define REQ_LOCAL 12
+#define REQ_MANUAL 13
+#define REQ_N_SOURCES 14
+#define REQ_SOURCE_DATA 15
+#define REQ_REKEY 16
+#define REQ_ALLOW 17
+#define REQ_ALLOWALL 18
+#define REQ_DENY 19
+#define REQ_DENYALL 20
+#define REQ_CMDALLOW 21
+#define REQ_CMDALLOWALL 22
+#define REQ_CMDDENY 23
+#define REQ_CMDDENYALL 24
+#define REQ_ACCHECK 25
+#define REQ_CMDACCHECK 26
+#define REQ_ADD_SERVER 27
+#define REQ_ADD_PEER 28
+#define REQ_DEL_SOURCE 29
+#define REQ_WRITERTC 30
+#define REQ_DFREQ 31
+#define REQ_DOFFSET 32
+#define REQ_TRACKING 33
+#define REQ_SOURCESTATS 34
+#define REQ_RTCREPORT 35
+#define REQ_TRIMRTC 36
+#define REQ_CYCLELOGS 37
+#define REQ_SUBNETS_ACCESSED 38
+#define REQ_CLIENT_ACCESSES 39
+#define REQ_CLIENT_ACCESSES_BY_INDEX 40
+#define REQ_MANUAL_LIST 41
+#define REQ_MANUAL_DELETE 42
+#define REQ_MAKESTEP 43
+#define REQ_ACTIVITY 44
+#define REQ_MODIFY_MINSTRATUM 45
+#define REQ_MODIFY_POLLTARGET 46
+#define REQ_MODIFY_MAXDELAYDEVRATIO 47
+#define REQ_RESELECT 48
+#define REQ_RESELECTDISTANCE 49
+#define REQ_MODIFY_MAKESTEP 50
+#define REQ_SMOOTHING 51
+#define REQ_SMOOTHTIME 52
+#define REQ_REFRESH 53
+#define REQ_SERVER_STATS 54
+#define REQ_CLIENT_ACCESSES_BY_INDEX2 55
+#define REQ_LOCAL2 56
+#define REQ_NTP_DATA 57
+#define REQ_ADD_SERVER2 58
+#define REQ_ADD_PEER2 59
+#define REQ_ADD_SERVER3 60
+#define REQ_ADD_PEER3 61
+#define REQ_SHUTDOWN 62
+#define REQ_ONOFFLINE 63
+#define REQ_ADD_SOURCE 64
+#define REQ_NTP_SOURCE_NAME 65
+#define REQ_RESET_SOURCES 66
+#define REQ_AUTH_DATA 67
+#define REQ_CLIENT_ACCESSES_BY_INDEX3 68
+#define REQ_SELECT_DATA 69
+#define REQ_RELOAD_SOURCES 70
+#define REQ_DOFFSET2 71
+#define N_REQUEST_TYPES 72
+
+/* Structure used to exchange timespecs independent of time_t size */
+typedef struct {
+  uint32_t tv_sec_high;
+  uint32_t tv_sec_low;
+  uint32_t tv_nsec;
+} Timespec;
+
+/* This is used in tv_sec_high for 32-bit timestamps */
+#define TV_NOHIGHSEC 0x7fffffff
+
+/* 32-bit floating-point format consisting of 7-bit signed exponent
+   and 25-bit signed coefficient without hidden bit.
+   The result is calculated as: 2^(exp - 25) * coef */
+typedef struct {
+  int32_t f;
+} Float;
+
+/* The EOR (end of record) fields are used by the offsetof operator in
+   pktlength.c, to get the number of bytes that ought to be
+   transmitted for each packet type. */
+
+typedef struct {
+  int32_t EOR;
+} REQ_Null;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t EOR;
+} REQ_Online;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t EOR;
+} REQ_Offline;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t n_good_samples;
+  int32_t n_total_samples;
+  int32_t EOR;
+} REQ_Burst;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_minpoll;
+  int32_t EOR;
+} REQ_Modify_Minpoll;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_maxpoll;
+  int32_t EOR;
+} REQ_Modify_Maxpoll;
+
+typedef struct {
+  int32_t pad;
+  int32_t EOR;
+} REQ_Dump;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay;
+  int32_t EOR;
+} REQ_Modify_Maxdelay;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay_ratio;
+  int32_t EOR;
+} REQ_Modify_Maxdelayratio;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay_dev_ratio;
+  int32_t EOR;
+} REQ_Modify_Maxdelaydevratio;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_min_stratum;
+  int32_t EOR;
+} REQ_Modify_Minstratum;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_poll_target;
+  int32_t EOR;
+} REQ_Modify_Polltarget;
+
+typedef struct {
+  Float new_max_update_skew;
+  int32_t EOR;
+} REQ_Modify_Maxupdateskew;
+
+typedef struct {
+  int32_t limit;
+  Float threshold;
+  int32_t EOR;
+} REQ_Modify_Makestep;
+
+typedef struct {
+  Timespec ts;
+  int32_t EOR;
+} REQ_Logon;
+
+typedef struct {
+  Timespec ts;
+  int32_t EOR;
+} REQ_Settime;
+
+typedef struct {
+  int32_t on_off;
+  int32_t stratum;
+  Float distance;
+  int32_t orphan;
+  int32_t EOR;
+} REQ_Local;
+
+typedef struct {
+  int32_t option;
+  int32_t EOR;
+} REQ_Manual;
+
+typedef struct {
+  int32_t index;
+  int32_t EOR;
+} REQ_Source_Data;
+
+typedef struct {
+  IPAddr ip;
+  int32_t subnet_bits;
+  int32_t EOR;
+} REQ_Allow_Deny;
+
+typedef struct {
+  IPAddr ip;
+  int32_t EOR;
+} REQ_Ac_Check;
+
+/* Source types in NTP source requests */
+#define REQ_ADDSRC_SERVER 1
+#define REQ_ADDSRC_PEER 2
+#define REQ_ADDSRC_POOL 3
+
+/* Flags used in NTP source requests */
+#define REQ_ADDSRC_ONLINE 0x1
+#define REQ_ADDSRC_AUTOOFFLINE 0x2
+#define REQ_ADDSRC_IBURST 0x4
+#define REQ_ADDSRC_PREFER 0x8
+#define REQ_ADDSRC_NOSELECT 0x10
+#define REQ_ADDSRC_TRUST 0x20
+#define REQ_ADDSRC_REQUIRE 0x40
+#define REQ_ADDSRC_INTERLEAVED 0x80
+#define REQ_ADDSRC_BURST 0x100
+#define REQ_ADDSRC_NTS 0x200
+#define REQ_ADDSRC_COPY 0x400
+#define REQ_ADDSRC_EF_EXP1 0x800
+
+typedef struct {
+  uint32_t type;
+  uint8_t name[256];
+  uint32_t port;
+  int32_t minpoll;
+  int32_t maxpoll;
+  int32_t presend_minpoll;
+  uint32_t min_stratum;
+  uint32_t poll_target;
+  uint32_t version;
+  uint32_t max_sources;
+  int32_t min_samples;
+  int32_t max_samples;
+  uint32_t authkey;
+  uint32_t nts_port;
+  Float max_delay;
+  Float max_delay_ratio;
+  Float max_delay_dev_ratio;
+  Float min_delay;
+  Float asymmetry;
+  Float offset;
+  uint32_t flags;
+  int32_t filter_length;
+  uint32_t cert_set;
+  Float max_delay_quant;
+  uint32_t reserved[1];
+  int32_t EOR;
+} REQ_NTP_Source;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_Del_Source;
+
+typedef struct {
+  Float dfreq;
+  int32_t EOR;
+} REQ_Dfreq;
+
+typedef struct {
+  Float doffset;
+  int32_t EOR;
+} REQ_Doffset;
+
+typedef struct {
+  uint32_t index;
+  int32_t EOR;
+} REQ_Sourcestats;
+
+/* This is based on the response size rather than the
+   request size */
+#define MAX_CLIENT_ACCESSES 8
+
+typedef struct {
+  uint32_t first_index;
+  uint32_t n_clients;
+  uint32_t min_hits;
+  uint32_t reset;
+  int32_t EOR;
+} REQ_ClientAccessesByIndex;
+
+typedef struct {
+  int32_t index;
+  int32_t EOR;
+} REQ_ManualDelete;
+
+typedef struct {
+  Float distance;
+  int32_t EOR;
+} REQ_ReselectDistance;
+
+#define REQ_SMOOTHTIME_RESET 0
+#define REQ_SMOOTHTIME_ACTIVATE 1
+
+typedef struct {
+  int32_t option;
+  int32_t EOR;
+} REQ_SmoothTime;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_NTPData;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_NTPSourceName;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_AuthData;
+
+typedef struct {
+  uint32_t index;
+  int32_t EOR;
+} REQ_SelectData;
+
+/* ================================================== */
+
+#define PKT_TYPE_CMD_REQUEST 1
+#define PKT_TYPE_CMD_REPLY 2
+
+/* This version number needs to be incremented whenever the packet
+   size and/or the format of any of the existing messages is changed.
+   Other changes, e.g. new command types, should be handled cleanly by
+   client.c and cmdmon.c anyway, so the version can stay the same.
+   
+   Version 1 : original version with fixed size packets
+
+   Version 2 : both command and reply packet sizes made capable of
+   being variable length.
+
+   Version 3 : NTP_Source message lengthened (auto_offline)
+
+   Version 4 : IPv6 addressing added, 64-bit time values, sourcestats 
+   and tracking reports extended, added flags to NTP source request,
+   trimmed source report, replaced fixed-point format with floating-point
+   and used also instead of integer microseconds, new commands: modify stratum,
+   modify polltarget, modify maxdelaydevratio, reselect, reselectdistance
+
+   Version 5 : auth data moved to the end of the packet to allow hashes with
+   different sizes, extended sources, tracking and activity reports, dropped
+   subnets accessed and client accesses
+
+   Version 6 : added padding to requests to prevent amplification attack,
+   changed maximum number of samples in manual list to 16, new commands: modify
+   makestep, smoothing, smoothtime
+
+   Support for authentication was removed later in version 6 of the protocol
+   and commands that required authentication are allowed only locally over Unix
+   domain socket.
+
+   Version 6 (no authentication) : changed format of client accesses by index
+   (two times), delta offset, and manual timestamp, added new fields and
+   flags to NTP source request and report, made length of manual list constant,
+   added new commands: authdata, ntpdata, onoffline, refresh, reset,
+   selectdata, serverstats, shutdown, sourcename
+ */
+
+#define PROTO_VERSION_NUMBER 6
+
+/* The oldest protocol versions that are compatible enough with the current
+   version to report a version mismatch for the server and the client */
+#define PROTO_VERSION_MISMATCH_COMPAT_SERVER 5
+#define PROTO_VERSION_MISMATCH_COMPAT_CLIENT 4
+
+/* The first protocol version using padding in requests */
+#define PROTO_VERSION_PADDING 6
+
+/* The maximum length of padding in request packet, currently
+   defined by CLIENT_ACCESSES_BY_INDEX3 */
+#define MAX_PADDING_LENGTH 484
+
+/* ================================================== */
+
+typedef struct {
+  uint8_t version; /* Protocol version */
+  uint8_t pkt_type; /* What sort of packet this is */
+  uint8_t res1;
+  uint8_t res2;
+  uint16_t command; /* Which command is being issued */
+  uint16_t attempt; /* How many resends the client has done
+                             (count up from zero for same sequence
+                             number) */
+  uint32_t sequence; /* Client's sequence number */
+  uint32_t pad1;
+  uint32_t pad2;
+
+  union {
+    REQ_Null null;
+    REQ_Online online;
+    REQ_Offline offline;
+    REQ_Burst burst;
+    REQ_Modify_Minpoll modify_minpoll;
+    REQ_Modify_Maxpoll modify_maxpoll;
+    REQ_Dump dump;
+    REQ_Modify_Maxdelay modify_maxdelay;
+    REQ_Modify_Maxdelayratio modify_maxdelayratio;
+    REQ_Modify_Maxdelaydevratio modify_maxdelaydevratio;
+    REQ_Modify_Minstratum modify_minstratum;
+    REQ_Modify_Polltarget modify_polltarget;
+    REQ_Modify_Maxupdateskew modify_maxupdateskew;
+    REQ_Modify_Makestep modify_makestep;
+    REQ_Logon logon;
+    REQ_Settime settime;
+    REQ_Local local;
+    REQ_Manual manual;
+    REQ_Source_Data source_data;
+    REQ_Allow_Deny allow_deny;
+    REQ_Ac_Check ac_check;
+    REQ_NTP_Source ntp_source;
+    REQ_Del_Source del_source;
+    REQ_Dfreq dfreq;
+    REQ_Doffset doffset;
+    REQ_Sourcestats sourcestats;
+    REQ_ClientAccessesByIndex client_accesses_by_index;
+    REQ_ManualDelete manual_delete;
+    REQ_ReselectDistance reselect_distance;
+    REQ_SmoothTime smoothtime;
+    REQ_NTPData ntp_data;
+    REQ_NTPSourceName ntp_source_name;
+    REQ_AuthData auth_data;
+    REQ_SelectData select_data;
+  } data; /* Command specific parameters */
+
+  /* Padding used to prevent traffic amplification.  It only defines the
+     maximum size of the packet, there is no hole after the data field. */
+  uint8_t padding[MAX_PADDING_LENGTH];
+
+} CMD_Request;
+
+/* ================================================== */
+/* Authority codes for command types */
+
+#define PERMIT_OPEN 0
+#define PERMIT_LOCAL 1
+#define PERMIT_AUTH 2
+
+/* ================================================== */
+
+/* Reply codes */
+#define RPY_NULL 1
+#define RPY_N_SOURCES 2
+#define RPY_SOURCE_DATA 3
+#define RPY_MANUAL_TIMESTAMP 4
+#define RPY_TRACKING 5
+#define RPY_SOURCESTATS 6
+#define RPY_RTC 7
+#define RPY_SUBNETS_ACCESSED 8
+#define RPY_CLIENT_ACCESSES 9
+#define RPY_CLIENT_ACCESSES_BY_INDEX 10
+#define RPY_MANUAL_LIST 11
+#define RPY_ACTIVITY 12
+#define RPY_SMOOTHING 13
+#define RPY_SERVER_STATS 14
+#define RPY_CLIENT_ACCESSES_BY_INDEX2 15
+#define RPY_NTP_DATA 16
+#define RPY_MANUAL_TIMESTAMP2 17
+#define RPY_MANUAL_LIST2 18
+#define RPY_NTP_SOURCE_NAME 19
+#define RPY_AUTH_DATA 20
+#define RPY_CLIENT_ACCESSES_BY_INDEX3 21
+#define RPY_SERVER_STATS2 22
+#define RPY_SELECT_DATA 23
+#define RPY_SERVER_STATS3 24
+#define N_REPLY_TYPES 25
+
+/* Status codes */
+#define STT_SUCCESS 0
+#define STT_FAILED 1
+#define STT_UNAUTH 2
+#define STT_INVALID 3
+#define STT_NOSUCHSOURCE 4
+#define STT_INVALIDTS 5
+#define STT_NOTENABLED 6
+#define STT_BADSUBNET 7
+#define STT_ACCESSALLOWED 8
+#define STT_ACCESSDENIED 9
+#define STT_NOHOSTACCESS 10 /* Deprecated */
+#define STT_SOURCEALREADYKNOWN 11
+#define STT_TOOMANYSOURCES 12
+#define STT_NORTC 13
+#define STT_BADRTCFILE 14
+#define STT_INACTIVE 15
+#define STT_BADSAMPLE 16
+#define STT_INVALIDAF 17
+#define STT_BADPKTVERSION 18
+#define STT_BADPKTLENGTH 19
+#define STT_INVALIDNAME 21
+
+typedef struct {
+  int32_t EOR;
+} RPY_Null;
+
+typedef struct {
+  uint32_t n_sources;
+  int32_t EOR;
+} RPY_N_Sources;
+
+#define RPY_SD_MD_CLIENT 0
+#define RPY_SD_MD_PEER   1
+#define RPY_SD_MD_REF    2
+
+#define RPY_SD_ST_SELECTED 0
+#define RPY_SD_ST_NONSELECTABLE 1
+#define RPY_SD_ST_FALSETICKER 2
+#define RPY_SD_ST_JITTERY 3
+#define RPY_SD_ST_UNSELECTED 4
+#define RPY_SD_ST_SELECTABLE 5
+
+typedef struct {
+  IPAddr ip_addr;
+  int16_t poll;
+  uint16_t stratum;
+  uint16_t state;
+  uint16_t mode;
+  uint16_t flags;
+  uint16_t reachability;
+  uint32_t  since_sample;
+  Float orig_latest_meas;
+  Float latest_meas;
+  Float latest_meas_err;
+  int32_t EOR;
+} RPY_Source_Data;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint16_t stratum;
+  uint16_t leap_status;
+  Timespec ref_time;
+  Float current_correction;
+  Float last_offset;
+  Float rms_offset;
+  Float freq_ppm;
+  Float resid_freq_ppm;
+  Float skew_ppm;
+  Float root_delay;
+  Float root_dispersion;
+  Float last_update_interval;
+  int32_t EOR;
+} RPY_Tracking;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint32_t n_samples;
+  uint32_t n_runs;
+  uint32_t span_seconds;
+  Float sd;
+  Float resid_freq_ppm;
+  Float skew_ppm;
+  Float est_offset;
+  Float est_offset_err;
+  int32_t EOR;
+} RPY_Sourcestats;
+
+typedef struct {
+  Timespec ref_time;
+  uint16_t n_samples;
+  uint16_t n_runs;
+  uint32_t span_seconds;
+  Float rtc_seconds_fast;
+  Float rtc_gain_rate_ppm;
+  int32_t EOR;
+} RPY_Rtc;
+
+typedef struct {
+  Float offset;
+  Float dfreq_ppm;
+  Float new_afreq_ppm;
+  int32_t EOR;
+} RPY_ManualTimestamp;
+
+typedef struct {
+  IPAddr ip;
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint32_t ntp_drops;
+  uint32_t nke_drops;
+  uint32_t cmd_drops;
+  int8_t ntp_interval;
+  int8_t nke_interval;
+  int8_t cmd_interval;
+  int8_t ntp_timeout_interval;
+  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
+  uint32_t last_cmd_hit_ago;
+} RPY_ClientAccesses_Client;
+
+typedef struct {
+  uint32_t n_indices;      /* how many indices there are in the server's table */
+  uint32_t next_index;     /* the index 1 beyond those processed on this call */
+  uint32_t n_clients;      /* the number of valid entries in the following array */
+  RPY_ClientAccesses_Client clients[MAX_CLIENT_ACCESSES];
+  int32_t EOR;
+} RPY_ClientAccessesByIndex;
+
+typedef struct {
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint32_t ntp_drops;
+  uint32_t nke_drops;
+  uint32_t cmd_drops;
+  uint32_t log_drops;
+  uint32_t ntp_auth_hits;
+  uint32_t ntp_interleaved_hits;
+  uint32_t ntp_timestamps;
+  uint32_t ntp_span_seconds;
+  int32_t EOR;
+} RPY_ServerStats;
+
+#define MAX_MANUAL_LIST_SAMPLES 16
+
+typedef struct {
+  Timespec when;
+  Float slewed_offset;
+  Float orig_offset;
+  Float residual;
+} RPY_ManualListSample;
+
+typedef struct {
+  uint32_t n_samples;
+  RPY_ManualListSample samples[MAX_MANUAL_LIST_SAMPLES];
+  int32_t EOR;
+} RPY_ManualList;
+
+typedef struct {
+  int32_t online;
+  int32_t offline;
+  int32_t burst_online;
+  int32_t burst_offline;
+  int32_t unresolved;
+  int32_t EOR;
+} RPY_Activity;
+
+#define RPY_SMT_FLAG_ACTIVE 0x1
+#define RPY_SMT_FLAG_LEAPONLY 0x2
+
+typedef struct {
+  uint32_t flags;
+  Float offset;
+  Float freq_ppm;
+  Float wander_ppm;
+  Float last_update_ago;
+  Float remaining_time;
+  int32_t EOR;
+} RPY_Smoothing;
+
+#define RPY_NTP_FLAGS_TESTS 0x3ff
+#define RPY_NTP_FLAG_INTERLEAVED 0x4000
+#define RPY_NTP_FLAG_AUTHENTICATED 0x8000
+
+typedef struct {
+  IPAddr remote_addr;
+  IPAddr local_addr;
+  uint16_t remote_port;
+  uint8_t leap;
+  uint8_t version;
+  uint8_t mode;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  Float root_delay;
+  Float root_dispersion;
+  uint32_t ref_id;
+  Timespec ref_time;
+  Float offset;
+  Float peer_delay;
+  Float peer_dispersion;
+  Float response_time;
+  Float jitter_asymmetry;
+  uint16_t flags;
+  uint8_t tx_tss_char;
+  uint8_t rx_tss_char;
+  uint32_t total_tx_count;
+  uint32_t total_rx_count;
+  uint32_t total_valid_count;
+  uint32_t total_good_count;
+  uint32_t reserved[3];
+  int32_t EOR;
+} RPY_NTPData;
+
+typedef struct {
+  uint8_t name[256];
+  int32_t EOR;
+} RPY_NTPSourceName;
+
+#define RPY_AD_MD_NONE 0
+#define RPY_AD_MD_SYMMETRIC 1
+#define RPY_AD_MD_NTS 2
+
+typedef struct {
+  uint16_t mode;
+  uint16_t key_type;
+  uint32_t key_id;
+  uint16_t key_length;
+  uint16_t ke_attempts;
+  uint32_t last_ke_ago;
+  uint16_t cookies;
+  uint16_t cookie_length;
+  uint16_t nak;
+  uint16_t pad;
+  int32_t EOR;
+} RPY_AuthData;
+
+#define RPY_SD_OPTION_NOSELECT 0x1
+#define RPY_SD_OPTION_PREFER 0x2
+#define RPY_SD_OPTION_TRUST 0x4
+#define RPY_SD_OPTION_REQUIRE 0x8
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint8_t state_char;
+  uint8_t authentication;
+  uint8_t leap;
+  uint8_t pad;
+  uint16_t conf_options;
+  uint16_t eff_options;
+  uint32_t last_sample_ago;
+  Float score;
+  Float lo_limit;
+  Float hi_limit;
+  int32_t EOR;
+} RPY_SelectData;
+
+typedef struct {
+  uint8_t version;
+  uint8_t pkt_type;
+  uint8_t res1;
+  uint8_t res2;
+  uint16_t command; /* Which command is being replied to */
+  uint16_t reply; /* Which format of reply this is */
+  uint16_t status; /* Status of command processing */
+  uint16_t pad1; /* Padding for compatibility and 4 byte alignment */
+  uint16_t pad2;
+  uint16_t pad3;
+  uint32_t sequence; /* Echo of client's sequence number */
+  uint32_t pad4;
+  uint32_t pad5;
+
+  union {
+    RPY_Null null;
+    RPY_N_Sources n_sources;
+    RPY_Source_Data source_data;
+    RPY_ManualTimestamp manual_timestamp;
+    RPY_Tracking tracking;
+    RPY_Sourcestats sourcestats;
+    RPY_Rtc rtc;
+    RPY_ClientAccessesByIndex client_accesses_by_index;
+    RPY_ServerStats server_stats;
+    RPY_ManualList manual_list;
+    RPY_Activity activity;
+    RPY_Smoothing smoothing;
+    RPY_NTPData ntp_data;
+    RPY_NTPSourceName ntp_source_name;
+    RPY_AuthData auth_data;
+    RPY_SelectData select_data;
+  } data; /* Reply specific parameters */
+
+} CMD_Reply;
+
+/* ================================================== */
+
+#endif /* GOT_CANDM_H */
diff --git a/client.c b/client.c
new file mode 100644
index 0000000..0a7bcc8
--- /dev/null
+++ b/client.c
@@ -0,0 +1,3451 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Lonnie Abelbeck  2016, 2018
+ * Copyright (C) Miroslav Lichvar  2009-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Command line client for configuring the daemon and obtaining status
+  from it whilst running.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "candm.h"
+#include "cmac.h"
+#include "logging.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "getdate.h"
+#include "cmdparse.h"
+#include "pktlength.h"
+#include "socket.h"
+#include "util.h"
+
+#ifdef FEAT_READLINE
+#include <editline/readline.h>
+#endif
+
+/* ================================================== */
+
+struct Address {
+  SCK_AddressType type;
+  union {
+    IPSockAddr ip;
+    char *path;
+  } addr;
+};
+
+static ARR_Instance server_addresses;
+
+static int sock_fd = -1;
+
+static volatile int quit = 0;
+
+static int on_terminal = 0;
+
+static int no_dns = 0;
+
+static int source_names = 0;
+
+static int csv_mode = 0;
+
+/* ================================================== */
+/* Log a message. This is a minimalistic replacement of the logging.c
+   implementation to avoid linking with it and other modules. */
+
+LOG_Severity log_min_severity = LOGS_INFO;
+
+void LOG_Message(LOG_Severity severity,
+#if DEBUG > 0
+                 int line_number, const char *filename, const char *function_name,
+#endif
+                 const char *format, ...)
+{
+  va_list ap;
+
+  if (severity < log_min_severity)
+    return;
+
+  va_start(ap, format);
+  vfprintf(stderr, format, ap);
+  putc('\n', stderr);
+  va_end(ap);
+}
+
+/* ================================================== */
+/* Read a single line of commands from standard input */
+
+#ifdef FEAT_READLINE
+static char **command_name_completion(const char *text, int start, int end);
+#endif
+
+static char *
+read_line(void)
+{
+  static char line[2048];
+  static const char *prompt = "chronyc> ";
+
+  if (on_terminal) {
+#ifdef FEAT_READLINE
+    char *cmd;
+
+    rl_attempted_completion_function = command_name_completion;
+    rl_basic_word_break_characters = " \t\n\r";
+
+    /* save line only if not empty */
+    cmd = readline(prompt);
+    if( cmd == NULL ) return( NULL );
+    
+    /* user pressed return */
+    if( *cmd != '\0' ) {
+      strncpy(line, cmd, sizeof(line) - 1);
+      line[sizeof(line) - 1] = '\0';
+      add_history(cmd);
+      /* free the buffer allocated by readline */
+      Free(cmd);
+    } else {
+      /* simulate the user has entered an empty line */
+      *line = '\0';
+    }
+    return( line );
+#else
+    printf("%s", prompt);
+    fflush(stdout);
+#endif
+  }
+  if (fgets(line, sizeof(line), stdin)) {
+    return line;
+  } else {
+    return NULL;
+  }
+  
+}
+
+/* ================================================== */
+
+static ARR_Instance
+get_addresses(const char *hostnames, int port)
+{
+  struct Address *addr;
+  ARR_Instance addrs;
+  char *hostname, *s1, *s2;
+  IPAddr ip_addrs[DNS_MAX_ADDRESSES];
+  int i;
+
+  addrs = ARR_CreateInstance(sizeof (*addr));
+  s1 = Strdup(hostnames);
+
+  /* Parse the comma-separated list of hostnames */
+  for (hostname = s1; hostname && *hostname; hostname = s2) {
+    s2 = strchr(hostname, ',');
+    if (s2)
+      *s2++ = '\0';
+
+    /* hostname starting with / is considered a path of Unix domain socket */
+    if (hostname[0] == '/') {
+      addr = ARR_GetNewElement(addrs);
+      addr->type = SCK_ADDR_UNIX;
+      addr->addr.path = Strdup(hostname);
+    } else {
+      if (DNS_Name2IPAddress(hostname, ip_addrs, DNS_MAX_ADDRESSES) != DNS_Success) {
+        DEBUG_LOG("Could not get IP address for %s", hostname);
+        continue;
+      }
+
+      for (i = 0; i < DNS_MAX_ADDRESSES && ip_addrs[i].family != IPADDR_UNSPEC; i++) {
+        addr = ARR_GetNewElement(addrs);
+        addr->type = SCK_ADDR_IP;
+        addr->addr.ip.ip_addr = ip_addrs[i];
+        addr->addr.ip.port = port;
+        DEBUG_LOG("Resolved %s to %s", hostname, UTI_IPToString(&ip_addrs[i]));
+      }
+    }
+  }
+
+  Free(s1);
+  return addrs;
+}
+
+/* ================================================== */
+
+static void
+free_addresses(ARR_Instance addresses)
+{
+  struct Address *addr;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(addresses); i++) {
+    addr = ARR_GetElement(addresses, i);
+
+    if (addr->type == SCK_ADDR_UNIX)
+      Free(addr->addr.path);
+  }
+
+  ARR_DestroyInstance(addresses);
+}
+
+/* ================================================== */
+/* Initialise the socket used to talk to the daemon */
+
+static int
+open_socket(struct Address *addr)
+{
+  char *dir, *local_addr;
+  size_t local_addr_len;
+
+  switch (addr->type) {
+    case SCK_ADDR_IP:
+      sock_fd = SCK_OpenUdpSocket(&addr->addr.ip, NULL, NULL, 0);
+      break;
+    case SCK_ADDR_UNIX:
+      /* Construct path of our socket.  Use the same directory as the server
+         socket and include our process ID to allow multiple chronyc instances
+         running at the same time. */
+
+      dir = UTI_PathToDir(addr->addr.path);
+      local_addr_len = strlen(dir) + 50;
+      local_addr = Malloc(local_addr_len);
+
+      snprintf(local_addr, local_addr_len, "%s/chronyc.%d.sock", dir, (int)getpid());
+
+      sock_fd = SCK_OpenUnixDatagramSocket(addr->addr.path, local_addr,
+                                           SCK_FLAG_ALL_PERMISSIONS);
+      Free(dir);
+      Free(local_addr);
+
+      break;
+    default:
+      assert(0);
+  }
+
+  if (sock_fd < 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+close_io(void)
+{
+  if (sock_fd < 0)
+    return;
+
+  SCK_RemoveSocket(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  sock_fd = -1;
+}
+
+/* ================================================== */
+
+static int
+open_io(void)
+{
+  static unsigned int address_index = 0;
+  struct Address *addr;
+
+  /* If a socket is already opened, close it and try the next address */
+  if (sock_fd >= 0) {
+    close_io();
+    address_index++;
+  }
+
+  /* Find an address for which a socket can be opened and connected */
+  for (; address_index < ARR_GetSize(server_addresses); address_index++) {
+    addr = ARR_GetElement(server_addresses, address_index);
+
+    if (open_socket(addr))
+      return 1;
+
+    close_io();
+  }
+
+  /* Start from the first address if called again */
+  address_index = 0;
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+bits_to_mask(int bits, int family, IPAddr *mask)
+{
+  int i;
+
+  mask->family = family;
+  switch (family) {
+    case IPADDR_INET4:
+      if (bits > 32 || bits < 0)
+        bits = 32;
+      if (bits > 0) {
+        mask->addr.in4 = -1;
+        mask->addr.in4 <<= 32 - bits;
+      } else {
+        mask->addr.in4 = 0;
+      }
+      break;
+    case IPADDR_INET6:
+      if (bits > 128 || bits < 0)
+        bits = 128;
+      for (i = 0; i < bits / 8; i++)
+        mask->addr.in6[i] = 0xff;
+      if (i < 16)
+        mask->addr.in6[i++] = (0xff << (8 - bits % 8)) & 0xff;
+      for (; i < 16; i++)
+        mask->addr.in6[i] = 0x0;
+      break;
+    case IPADDR_ID:
+      mask->family = IPADDR_UNSPEC;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static int
+parse_source_address(char *word, IPAddr *address)
+{
+  if (UTI_StringToIdIP(word, address))
+    return 1;
+
+  if (DNS_Name2IPAddress(word, address, 1) == DNS_Success)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+read_mask_address(char *line, IPAddr *mask, IPAddr *address)
+{
+  unsigned int bits;
+  char *p, *q;
+
+  p = line;
+  if (!*p) {
+    mask->family = address->family = IPADDR_UNSPEC;
+    return 1;
+  } else {
+    q = strchr(p, '/');
+    if (q) {
+      *q++ = 0;
+      if (UTI_StringToIP(p, mask)) {
+        p = q;
+        if (UTI_StringToIP(p, address)) {
+          if (address->family == mask->family)
+            return 1;
+        } else if (sscanf(p, "%u", &bits) == 1) {
+          *address = *mask;
+          bits_to_mask(bits, address->family, mask);
+          return 1;
+        }
+      }
+    } else {
+      if (parse_source_address(p, address)) {
+        bits_to_mask(-1, address->family, mask);
+        return 1;
+      } else {
+        LOG(LOGS_ERR, "Could not get address for hostname");
+        return 0;
+      }
+    }
+  }
+
+  LOG(LOGS_ERR, "Invalid syntax for mask/address");
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_offline(CMD_Request *msg, char *line)
+{
+  IPAddr mask, address;
+  int ok;
+
+  if (read_mask_address(line, &mask, &address)) {
+    UTI_IPHostToNetwork(&mask, &msg->data.offline.mask);
+    UTI_IPHostToNetwork(&address, &msg->data.offline.address);
+    msg->command = htons(REQ_OFFLINE);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+
+static int
+process_cmd_online(CMD_Request *msg, char *line)
+{
+  IPAddr mask, address;
+  int ok;
+
+  if (read_mask_address(line, &mask, &address)) {
+    UTI_IPHostToNetwork(&mask, &msg->data.online.mask);
+    UTI_IPHostToNetwork(&address, &msg->data.online.address);
+    msg->command = htons(REQ_ONLINE);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static void
+process_cmd_onoffline(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_ONOFFLINE);
+}
+
+/* ================================================== */
+
+static int
+read_address_integer(char *line, IPAddr *address, int *value)
+{
+  char *hostname;
+  int ok = 0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(line, "%d", value) != 1) {
+    LOG(LOGS_ERR, "Invalid syntax for address value");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      ok = 1;
+    }
+  }
+
+  return ok;
+
+}
+
+
+/* ================================================== */
+
+static int
+read_address_double(char *line, IPAddr *address, double *value)
+{
+  char *hostname;
+  int ok = 0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(line, "%lf", value) != 1) {
+    LOG(LOGS_ERR, "Invalid syntax for address value");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      ok = 1;
+    }
+  }
+
+  return ok;
+
+}
+
+
+/* ================================================== */
+
+static int
+process_cmd_minpoll(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int minpoll;
+  int ok;
+  
+  if (read_address_integer(line, &address, &minpoll)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_minpoll.address);
+    msg->data.modify_minpoll.new_minpoll = htonl(minpoll);
+    msg->command = htons(REQ_MODIFY_MINPOLL);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxpoll(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int maxpoll;
+  int ok;
+  
+  if (read_address_integer(line, &address, &maxpoll)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxpoll.address);
+    msg->data.modify_maxpoll.new_maxpoll = htonl(maxpoll);
+    msg->command = htons(REQ_MODIFY_MAXPOLL);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelay(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelay.address);
+    msg->data.modify_maxdelay.new_max_delay = UTI_FloatHostToNetwork(max_delay);
+    msg->command = htons(REQ_MODIFY_MAXDELAY);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelaydevratio(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay_dev_ratio;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay_dev_ratio)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelaydevratio.address);
+    msg->data.modify_maxdelayratio.new_max_delay_ratio = UTI_FloatHostToNetwork(max_delay_dev_ratio);
+    msg->command = htons(REQ_MODIFY_MAXDELAYDEVRATIO);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelayratio(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay_ratio;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay_ratio)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelayratio.address);
+    msg->data.modify_maxdelayratio.new_max_delay_ratio = UTI_FloatHostToNetwork(max_delay_ratio);
+    msg->command = htons(REQ_MODIFY_MAXDELAYRATIO);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_minstratum(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int min_stratum;
+  int ok;
+  
+  if (read_address_integer(line, &address, &min_stratum)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_minstratum.address);
+    msg->data.modify_minstratum.new_min_stratum = htonl(min_stratum);
+    msg->command = htons(REQ_MODIFY_MINSTRATUM);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_polltarget(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int poll_target;
+  int ok;
+  
+  if (read_address_integer(line, &address, &poll_target)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_polltarget.address);
+    msg->data.modify_polltarget.new_poll_target = htonl(poll_target);
+    msg->command = htons(REQ_MODIFY_POLLTARGET);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxupdateskew(CMD_Request *msg, char *line)
+{
+  int ok;
+  double new_max_update_skew;
+  
+  if (sscanf(line, "%lf", &new_max_update_skew) == 1) {
+    msg->data.modify_maxupdateskew.new_max_update_skew = UTI_FloatHostToNetwork(new_max_update_skew);
+    msg->command = htons(REQ_MODIFY_MAXUPDATESKEW);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static void
+process_cmd_dump(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_DUMP);
+  msg->data.dump.pad = htonl(0);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_writertc(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_WRITERTC);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_trimrtc(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_TRIMRTC);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_cyclelogs(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_CYCLELOGS);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_burst(CMD_Request *msg, char *line)
+{
+  int n_good_samples, n_total_samples;
+  char *s1, *s2;
+  IPAddr address, mask;
+
+  s1 = line;
+  s2 = CPS_SplitWord(s1);
+  CPS_SplitWord(s2);
+
+  if (sscanf(s1, "%d/%d", &n_good_samples, &n_total_samples) != 2) {
+    LOG(LOGS_ERR, "Invalid syntax for burst command");
+    return 0;
+  }
+
+  mask.family = address.family = IPADDR_UNSPEC;
+  if (*s2 && !read_mask_address(s2, &mask, &address)) {
+    return 0;
+  }
+
+  msg->command = htons(REQ_BURST);
+  msg->data.burst.n_good_samples = ntohl(n_good_samples);
+  msg->data.burst.n_total_samples = ntohl(n_total_samples);
+
+  UTI_IPHostToNetwork(&mask, &msg->data.burst.mask);
+  UTI_IPHostToNetwork(&address, &msg->data.burst.address);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_local(CMD_Request *msg, char *line)
+{
+  int on_off, stratum = 0, orphan = 0;
+  double distance = 0.0;
+
+  if (!strcmp(line, "off")) {
+    on_off = 0;
+  } else if (CPS_ParseLocal(line, &stratum, &orphan, &distance)) {
+    on_off = 1;
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for local command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_LOCAL2);
+  msg->data.local.on_off = htonl(on_off);
+  msg->data.local.stratum = htonl(stratum);
+  msg->data.local.distance = UTI_FloatHostToNetwork(distance);
+  msg->data.local.orphan = htonl(orphan);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_manual(CMD_Request *msg, const char *line)
+{
+  const char *p;
+
+  p = line;
+
+  if (!strcmp(p, "off")) {
+    msg->data.manual.option = htonl(0);
+  } else if (!strcmp(p, "on")) {
+    msg->data.manual.option = htonl(1);
+  } else if (!strcmp(p, "reset")) {
+    msg->data.manual.option = htonl(2);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for manual command");
+    return 0;
+  }
+  msg->command = htons(REQ_MANUAL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_allowdeny(CMD_Request *msg, char *line, int cmd, int allcmd)
+{
+  int all, subnet_bits;
+  IPAddr ip;
+  
+  if (!CPS_ParseAllowDeny(line, &all, &ip, &subnet_bits)) {
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+
+  msg->command = htons(all ? allcmd : cmd);
+  UTI_IPHostToNetwork(&ip, &msg->data.allow_deny.ip);
+  msg->data.allow_deny.subnet_bits = htonl(subnet_bits);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_accheck(CMD_Request *msg, char *line)
+{
+  IPAddr ip;
+  msg->command = htons(REQ_ACCHECK);
+  if (DNS_Name2IPAddress(line, &ip, 1) == DNS_Success) {
+    UTI_IPHostToNetwork(&ip, &msg->data.ac_check.ip);
+    return 1;
+  } else {    
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_cmdaccheck(CMD_Request *msg, char *line)
+{
+  IPAddr ip;
+  msg->command = htons(REQ_CMDACCHECK);
+  if (DNS_Name2IPAddress(line, &ip, 1) == DNS_Success) {
+    UTI_IPHostToNetwork(&ip, &msg->data.ac_check.ip);
+    return 1;
+  } else {    
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_dfreq(CMD_Request *msg, char *line)
+{
+  double dfreq;
+
+  msg->command = htons(REQ_DFREQ);
+
+  if (sscanf(line, "%lf", &dfreq) != 1) {
+    LOG(LOGS_ERR, "Invalid value");
+    return 0;
+  }
+
+  msg->data.dfreq.dfreq = UTI_FloatHostToNetwork(dfreq);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_doffset(CMD_Request *msg, char *line)
+{
+  double doffset;
+
+  msg->command = htons(REQ_DOFFSET2);
+
+  if (sscanf(line, "%lf", &doffset) != 1) {
+    LOG(LOGS_ERR, "Invalid value");
+    return 0;
+  }
+
+  msg->data.doffset.doffset = UTI_FloatHostToNetwork(doffset);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_add_source(CMD_Request *msg, char *line)
+{
+  CPS_NTP_Source data;
+  IPAddr ip_addr;
+  int result = 0, status, type;
+  const char *opt_name, *word;
+  
+  msg->command = htons(REQ_ADD_SOURCE);
+
+  word = line;
+  line = CPS_SplitWord(line);
+
+  if (!strcasecmp(word, "server")) {
+    type = REQ_ADDSRC_SERVER;
+  } else if (!strcasecmp(word, "peer")) {
+    type = REQ_ADDSRC_PEER;
+  } else if (!strcasecmp(word, "pool")) {
+    type = REQ_ADDSRC_POOL;
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for add command");
+    return 0;
+  }
+
+  status = CPS_ParseNTPSourceAdd(line, &data);
+  switch (status) {
+    case 0:
+      LOG(LOGS_ERR, "Invalid syntax for add command");
+      break;
+    default:
+      /* Verify that the address is resolvable (chronyc and chronyd are
+         assumed to be running on the same host) */
+      if (strlen(data.name) >= sizeof (msg->data.ntp_source.name) ||
+          DNS_Name2IPAddress(data.name, &ip_addr, 1) != DNS_Success) {
+        LOG(LOGS_ERR, "Invalid host/IP address");
+        break;
+      }
+
+      opt_name = NULL;
+      if (opt_name) {
+        LOG(LOGS_ERR, "%s can't be set in chronyc", opt_name);
+        break;
+      }
+
+      msg->data.ntp_source.type = htonl(type);
+      if (strlen(data.name) >= sizeof (msg->data.ntp_source.name))
+        assert(0);
+      strncpy((char *)msg->data.ntp_source.name, data.name,
+              sizeof (msg->data.ntp_source.name));
+      msg->data.ntp_source.port = htonl(data.port);
+      msg->data.ntp_source.minpoll = htonl(data.params.minpoll);
+      msg->data.ntp_source.maxpoll = htonl(data.params.maxpoll);
+      msg->data.ntp_source.presend_minpoll = htonl(data.params.presend_minpoll);
+      msg->data.ntp_source.min_stratum = htonl(data.params.min_stratum);
+      msg->data.ntp_source.poll_target = htonl(data.params.poll_target);
+      msg->data.ntp_source.version = htonl(data.params.version);
+      msg->data.ntp_source.max_sources = htonl(data.params.max_sources);
+      msg->data.ntp_source.min_samples = htonl(data.params.min_samples);
+      msg->data.ntp_source.max_samples = htonl(data.params.max_samples);
+      msg->data.ntp_source.authkey = htonl(data.params.authkey);
+      msg->data.ntp_source.nts_port = htonl(data.params.nts_port);
+      msg->data.ntp_source.max_delay = UTI_FloatHostToNetwork(data.params.max_delay);
+      msg->data.ntp_source.max_delay_ratio = UTI_FloatHostToNetwork(data.params.max_delay_ratio);
+      msg->data.ntp_source.max_delay_dev_ratio =
+        UTI_FloatHostToNetwork(data.params.max_delay_dev_ratio);
+      msg->data.ntp_source.min_delay = UTI_FloatHostToNetwork(data.params.min_delay);
+      msg->data.ntp_source.asymmetry = UTI_FloatHostToNetwork(data.params.asymmetry);
+      msg->data.ntp_source.offset = UTI_FloatHostToNetwork(data.params.offset);
+      msg->data.ntp_source.flags = htonl(
+          (data.params.connectivity == SRC_ONLINE ? REQ_ADDSRC_ONLINE : 0) |
+          (data.params.auto_offline ? REQ_ADDSRC_AUTOOFFLINE : 0) |
+          (data.params.iburst ? REQ_ADDSRC_IBURST : 0) |
+          (data.params.interleaved ? REQ_ADDSRC_INTERLEAVED : 0) |
+          (data.params.burst ? REQ_ADDSRC_BURST : 0) |
+          (data.params.nts ? REQ_ADDSRC_NTS : 0) |
+          (data.params.copy ? REQ_ADDSRC_COPY : 0) |
+          (data.params.ext_fields & NTP_EF_FLAG_EXP1 ? REQ_ADDSRC_EF_EXP1 : 0) |
+          (data.params.sel_options & SRC_SELECT_PREFER ? REQ_ADDSRC_PREFER : 0) |
+          (data.params.sel_options & SRC_SELECT_NOSELECT ? REQ_ADDSRC_NOSELECT : 0) |
+          (data.params.sel_options & SRC_SELECT_TRUST ? REQ_ADDSRC_TRUST : 0) |
+          (data.params.sel_options & SRC_SELECT_REQUIRE ? REQ_ADDSRC_REQUIRE : 0));
+      msg->data.ntp_source.filter_length = htonl(data.params.filter_length);
+      msg->data.ntp_source.cert_set = htonl(data.params.cert_set);
+      msg->data.ntp_source.max_delay_quant =
+        UTI_FloatHostToNetwork(data.params.max_delay_quant);
+      memset(msg->data.ntp_source.reserved, 0, sizeof (msg->data.ntp_source.reserved));
+
+      result = 1;
+
+      break;
+  }
+
+  return result;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_delete(CMD_Request *msg, char *line)
+{
+  char *hostname;
+  int ok = 0;
+  IPAddr address;
+
+  msg->command = htons(REQ_DEL_SOURCE);
+  hostname = line;
+  CPS_SplitWord(line);
+
+  if (!*hostname) {
+    LOG(LOGS_ERR, "Invalid syntax for address");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, &address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      UTI_IPHostToNetwork(&address, &msg->data.del_source.ip_addr);
+      ok = 1;
+    }
+  }
+
+  return ok;
+  
+}
+
+/* ================================================== */
+
+static void
+give_help(void)
+{
+  int line, len;
+  const char *s, cols[] =
+    "System clock:\0\0"
+    "tracking\0Display system time information\0"
+    "makestep\0Correct clock by stepping immediately\0"
+    "makestep <threshold> <updates>\0Configure automatic clock stepping\0"
+    "maxupdateskew <skew>\0Modify maximum valid skew to update frequency\0"
+    "waitsync [<max-tries> [<max-correction> [<max-skew> [<interval>]]]]\0"
+                          "Wait until synchronised in specified limits\0"
+    "\0\0"
+    "Time sources:\0\0"
+    "sources [-a] [-v]\0Display information about current sources\0"
+    "sourcestats [-a] [-v]\0Display statistics about collected measurements\0"
+    "selectdata [-a] [-v]\0Display information about source selection\0"
+    "reselect\0Force reselecting synchronisation source\0"
+    "reselectdist <dist>\0Modify reselection distance\0"
+    "\0\0"
+    "NTP sources:\0\0"
+    "activity\0Check how many NTP sources are online/offline\0"
+    "authdata [-a] [-v]\0Display information about authentication\0"
+    "ntpdata [<address>]\0Display information about last valid measurement\0"
+    "add server <name> [options]\0Add new NTP server\0"
+    "add pool <name> [options]\0Add new pool of NTP servers\0"
+    "add peer <name> [options]\0Add new NTP peer\0"
+    "delete <address>\0Remove server or peer\0"
+    "burst <n-good>/<n-max> [[<mask>/]<address>]\0Start rapid set of measurements\0"
+    "maxdelay <address> <delay>\0Modify maximum valid sample delay\0"
+    "maxdelayratio <address> <ratio>\0Modify maximum valid delay/minimum ratio\0"
+    "maxdelaydevratio <address> <ratio>\0Modify maximum valid delay/deviation ratio\0"
+    "minpoll <address> <poll>\0Modify minimum polling interval\0"
+    "maxpoll <address> <poll>\0Modify maximum polling interval\0"
+    "minstratum <address> <stratum>\0Modify minimum stratum\0"
+    "offline [[<mask>/]<address>]\0Set sources in subnet to offline status\0"
+    "online [[<mask>/]<address>]\0Set sources in subnet to online status\0"
+    "onoffline\0Set all sources to online or offline status\0"
+    "\0according to network configuration\0"
+    "polltarget <address> <target>\0Modify poll target\0"
+    "refresh\0Refresh IP addresses\0"
+    "reload sources\0Re-read *.sources files\0"
+    "sourcename <address>\0Display original name\0"
+    "\0\0"
+    "Manual time input:\0\0"
+    "manual off|on|reset\0Disable/enable/reset settime command\0"
+    "manual list\0Show previous settime entries\0"
+    "manual delete <index>\0Delete previous settime entry\0"
+    "settime <time>\0Set daemon time\0"
+    "\0(e.g. Sep 25, 2015 16:30:05 or 16:30:05)\0"
+    "\0\0NTP access:\0\0"
+    "accheck <address>\0Check whether address is allowed\0"
+    "clients [-p <packets>] [-k] [-r]\0Report on clients that accessed the server\0"
+    "serverstats\0Display statistics of the server\0"
+    "allow [<subnet>]\0Allow access to subnet as a default\0"
+    "allow all [<subnet>]\0Allow access to subnet and all children\0"
+    "deny [<subnet>]\0Deny access to subnet as a default\0"
+    "deny all [<subnet>]\0Deny access to subnet and all children\0"
+    "local [options]\0Serve time even when not synchronised\0"
+    "local off\0Don't serve time when not synchronised\0"
+    "smoothtime reset|activate\0Reset/activate time smoothing\0"
+    "smoothing\0Display current time smoothing state\0"
+    "\0\0"
+    "Monitoring access:\0\0"
+    "cmdaccheck <address>\0Check whether address is allowed\0"
+    "cmdallow [<subnet>]\0Allow access to subnet as a default\0"
+    "cmdallow all [<subnet>]\0Allow access to subnet and all children\0"
+    "cmddeny [<subnet>]\0Deny access to subnet as a default\0"
+    "cmddeny all [<subnet>]\0Deny access to subnet and all children\0"
+    "\0\0"
+    "Real-time clock:\0\0"
+    "rtcdata\0Print current RTC performance parameters\0"
+    "trimrtc\0Correct RTC relative to system clock\0"
+    "writertc\0Save RTC performance parameters to file\0"
+    "\0\0"
+    "Other daemon commands:\0\0"
+    "cyclelogs\0Close and re-open log files\0"
+    "dump\0Dump measurements and NTS keys/cookies\0"
+    "rekey\0Re-read keys\0"
+    "reset sources\0Drop all measurements\0"
+    "shutdown\0Stop daemon\0"
+    "\0\0"
+    "Client commands:\0\0"
+    "dns -n|+n\0Disable/enable resolving IP addresses to hostnames\0"
+    "dns -4|-6|-46\0Resolve hostnames only to IPv4/IPv6/both addresses\0"
+    "timeout <milliseconds>\0Set initial response timeout\0"
+    "retries <retries>\0Set maximum number of retries\0"
+    "keygen [<id> [<type> [<bits>]]]\0Generate key for key file\0"
+    "exit|quit\0Leave the program\0"
+    "help\0Generate this help\0"
+    "\0";
+
+  /* Indent the second column */
+  for (s = cols, line = 0; s < cols + sizeof (cols); s += len + 1, line++) {
+    len = strlen(s);
+    printf(line % 2 == 0 ? (len >= 28 ? "%s\n%28s" : "%-28s%s") : "%s%s\n",
+           s, "");
+  }
+}
+
+/* ================================================== */
+/* Tab-completion when editline is available */
+
+#ifdef FEAT_READLINE
+
+enum {
+  TAB_COMPLETE_BASE_CMDS,
+  TAB_COMPLETE_ADD_OPTS,
+  TAB_COMPLETE_MANUAL_OPTS,
+  TAB_COMPLETE_RELOAD_OPTS,
+  TAB_COMPLETE_RESET_OPTS,
+  TAB_COMPLETE_SOURCES_OPTS,
+  TAB_COMPLETE_SOURCESTATS_OPTS,
+  TAB_COMPLETE_AUTHDATA_OPTS,
+  TAB_COMPLETE_SELECTDATA_OPTS,
+  TAB_COMPLETE_MAX_INDEX
+};
+
+static int tab_complete_index;
+
+static char *
+command_name_generator(const char *text, int state)
+{
+  const char *name, **names[TAB_COMPLETE_MAX_INDEX];
+  const char *base_commands[] = {
+    "accheck", "activity", "add", "allow", "authdata", "burst",
+    "clients", "cmdaccheck", "cmdallow", "cmddeny", "cyclelogs", "delete",
+    "deny", "dns", "dump", "exit", "help", "keygen", "local", "makestep",
+    "manual", "maxdelay", "maxdelaydevratio", "maxdelayratio", "maxpoll",
+    "maxupdateskew", "minpoll", "minstratum", "ntpdata", "offline", "online", "onoffline",
+    "polltarget", "quit", "refresh", "rekey", "reload", "reselect", "reselectdist", "reset",
+    "retries", "rtcdata", "selectdata", "serverstats", "settime", "shutdown", "smoothing",
+    "smoothtime", "sourcename", "sources", "sourcestats",
+    "timeout", "tracking", "trimrtc", "waitsync", "writertc",
+    NULL
+  };
+  const char *add_options[] = { "peer", "pool", "server", NULL };
+  const char *manual_options[] = { "on", "off", "delete", "list", "reset", NULL };
+  const char *reset_options[] = { "sources", NULL };
+  const char *reload_options[] = { "sources", NULL };
+  const char *common_source_options[] = { "-a", "-v", NULL };
+  static int list_index, len;
+
+  names[TAB_COMPLETE_BASE_CMDS] = base_commands;
+  names[TAB_COMPLETE_ADD_OPTS] = add_options;
+  names[TAB_COMPLETE_MANUAL_OPTS] = manual_options;
+  names[TAB_COMPLETE_RELOAD_OPTS] = reload_options;
+  names[TAB_COMPLETE_RESET_OPTS] = reset_options;
+  names[TAB_COMPLETE_AUTHDATA_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SELECTDATA_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SOURCES_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SOURCESTATS_OPTS] = common_source_options;
+
+  if (!state) {
+    list_index = 0;
+    len = strlen(text);
+  }
+
+  while ((name = names[tab_complete_index][list_index++])) {
+    if (strncmp(name, text, len) == 0) {
+      return strdup(name);
+    }
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static char **
+command_name_completion(const char *text, int start, int end)
+{
+  char first[32];
+
+  snprintf(first, MIN(sizeof (first), start + 1), "%s", rl_line_buffer);
+  rl_attempted_completion_over = 1;
+
+  if (!strcmp(first, "add ")) {
+    tab_complete_index = TAB_COMPLETE_ADD_OPTS;
+  } else if (!strcmp(first, "authdata ")) {
+    tab_complete_index = TAB_COMPLETE_AUTHDATA_OPTS;
+  } else if (!strcmp(first, "manual ")) {
+    tab_complete_index = TAB_COMPLETE_MANUAL_OPTS;
+  } else if (!strcmp(first, "reload ")) {
+    tab_complete_index = TAB_COMPLETE_RELOAD_OPTS;
+  } else if (!strcmp(first, "reset ")) {
+    tab_complete_index = TAB_COMPLETE_RESET_OPTS;
+  } else if (!strcmp(first, "selectdata ")) {
+    tab_complete_index = TAB_COMPLETE_SELECTDATA_OPTS;
+  } else if (!strcmp(first, "sources ")) {
+    tab_complete_index = TAB_COMPLETE_SOURCES_OPTS;
+  } else if (!strcmp(first, "sourcestats ")) {
+    tab_complete_index = TAB_COMPLETE_SOURCESTATS_OPTS;
+  } else if (first[0] == '\0') {
+    tab_complete_index = TAB_COMPLETE_BASE_CMDS;
+  } else {
+    return NULL;
+  }
+
+  return rl_completion_matches(text, command_name_generator);
+}
+#endif
+
+/* ================================================== */
+
+static int max_retries = 2;
+static int initial_timeout = 1000;
+static int proto_version = PROTO_VERSION_NUMBER;
+
+/* This is the core protocol module.  Complete particular fields in
+   the outgoing packet, send it, wait for a response, handle retries,
+   etc.  Returns a Boolean indicating whether the protocol was
+   successful or not.*/
+
+static int
+submit_request(CMD_Request *request, CMD_Reply *reply)
+{
+  int select_status;
+  int recv_status;
+  int read_length;
+  int command_length;
+  int padding_length;
+  struct timespec ts_now, ts_start;
+  struct timeval tv;
+  int n_attempts, new_attempt;
+  double timeout;
+  fd_set rdfd;
+
+  request->pkt_type = PKT_TYPE_CMD_REQUEST;
+  request->res1 = 0;
+  request->res2 = 0;
+  request->pad1 = 0;
+  request->pad2 = 0;
+
+  n_attempts = 0;
+  new_attempt = 1;
+
+  do {
+    if (gettimeofday(&tv, NULL))
+      return 0;
+
+    if (new_attempt) {
+      new_attempt = 0;
+
+      if (n_attempts > max_retries)
+        return 0;
+
+      UTI_TimevalToTimespec(&tv, &ts_start);
+
+      UTI_GetRandomBytes(&request->sequence, sizeof (request->sequence));
+      request->attempt = htons(n_attempts);
+      request->version = proto_version;
+      command_length = PKL_CommandLength(request);
+      padding_length = PKL_CommandPaddingLength(request);
+      assert(command_length > 0 && command_length > padding_length);
+
+      n_attempts++;
+
+      /* Zero the padding to not send any uninitialized data */
+      memset(((char *)request) + command_length - padding_length, 0, padding_length);
+
+      if (sock_fd < 0) {
+        DEBUG_LOG("No socket to send request");
+        return 0;
+      }
+
+      if (SCK_Send(sock_fd, (void *)request, command_length, 0) < 0)
+        return 0;
+    }
+
+    UTI_TimevalToTimespec(&tv, &ts_now);
+
+    /* Check if the clock wasn't stepped back */
+    if (UTI_CompareTimespecs(&ts_now, &ts_start) < 0)
+      ts_start = ts_now;
+
+    timeout = initial_timeout / 1000.0 * (1U << (n_attempts - 1)) -
+              UTI_DiffTimespecsToDouble(&ts_now, &ts_start);
+    DEBUG_LOG("Timeout %f seconds", timeout);
+
+    /* Avoid calling select() with an invalid timeout */
+    if (timeout <= 0.0) {
+      new_attempt = 1;
+      continue;
+    }
+
+    UTI_DoubleToTimeval(timeout, &tv);
+
+    FD_ZERO(&rdfd);
+    FD_SET(sock_fd, &rdfd);
+
+    if (quit)
+      return 0;
+
+    select_status = select(sock_fd + 1, &rdfd, NULL, NULL, &tv);
+
+    if (select_status < 0) {
+      DEBUG_LOG("select failed : %s", strerror(errno));
+      return 0;
+    } else if (select_status == 0) {
+      /* Timeout must have elapsed, try a resend? */
+      new_attempt = 1;
+    } else {
+      recv_status = SCK_Receive(sock_fd, reply, sizeof (*reply), 0);
+      
+      if (recv_status < 0) {
+        new_attempt = 1;
+      } else {
+        read_length = recv_status;
+        
+        /* Check if the header is valid */
+        if (read_length < offsetof(CMD_Reply, data) ||
+            (reply->version != proto_version &&
+             !(reply->version >= PROTO_VERSION_MISMATCH_COMPAT_CLIENT &&
+               ntohs(reply->status) == STT_BADPKTVERSION)) ||
+            reply->pkt_type != PKT_TYPE_CMD_REPLY ||
+            reply->res1 != 0 ||
+            reply->res2 != 0 ||
+            reply->command != request->command ||
+            reply->sequence != request->sequence) {
+          DEBUG_LOG("Invalid reply");
+          continue;
+        }
+        
+#if PROTO_VERSION_NUMBER == 6
+        /* Protocol version 5 is similar to 6 except there is no padding.
+           If a version 5 reply with STT_BADPKTVERSION is received,
+           switch our version and try again. */
+        if (proto_version == PROTO_VERSION_NUMBER &&
+            reply->version == PROTO_VERSION_NUMBER - 1) {
+          proto_version = PROTO_VERSION_NUMBER - 1;
+          n_attempts--;
+          new_attempt = 1;
+          continue;
+        }
+#else
+#error unknown compatibility with PROTO_VERSION - 1
+#endif
+
+        /* Check that the packet contains all data it is supposed to have.
+           Unknown responses will always pass this test as their expected
+           length is zero. */
+        if (read_length < PKL_ReplyLength(reply)) {
+          DEBUG_LOG("Reply too short");
+          new_attempt = 1;
+          continue;
+        }
+
+        /* Good packet received, print out results */
+        DEBUG_LOG("Reply cmd=%d reply=%d stat=%d",
+                  ntohs(reply->command), ntohs(reply->reply), ntohs(reply->status));
+        break;
+      }
+    }
+  } while (1);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+request_reply(CMD_Request *request, CMD_Reply *reply, int requested_reply, int verbose)
+{
+  int status;
+
+  while (!submit_request(request, reply)) {
+    /* Try connecting to other addresses before giving up */
+    if (open_io())
+      continue;
+    printf("506 Cannot talk to daemon\n");
+    return 0;
+  }
+
+  status = ntohs(reply->status);
+        
+  if (verbose || status != STT_SUCCESS) {
+    switch (status) {
+      case STT_SUCCESS:
+        printf("200 OK");
+        break;
+      case STT_ACCESSALLOWED:
+        printf("208 Access allowed");
+        break;
+      case STT_ACCESSDENIED:
+        printf("209 Access denied");
+        break;
+      case STT_FAILED:
+        printf("500 Failure");
+        break;
+      case STT_UNAUTH:
+        printf("501 Not authorised");
+        break;
+      case STT_INVALID:
+        printf("502 Invalid command");
+        break;
+      case STT_NOSUCHSOURCE:
+        printf("503 No such source");
+        break;
+      case STT_INVALIDTS:
+        printf("504 Duplicate or stale logon detected");
+        break;
+      case STT_NOTENABLED:
+        printf("505 Facility not enabled in daemon");
+        break;
+      case STT_BADSUBNET:
+        printf("507 Bad subnet");
+        break;
+      case STT_NOHOSTACCESS:
+        printf("510 No command access from this host");
+        break;
+      case STT_SOURCEALREADYKNOWN:
+        printf("511 Source already present");
+        break;
+      case STT_TOOMANYSOURCES:
+        printf("512 Too many sources present");
+        break;
+      case STT_NORTC:
+        printf("513 RTC driver not running");
+        break;
+      case STT_BADRTCFILE:
+        printf("514 Can't write RTC parameters");
+        break;
+      case STT_INVALIDAF:
+        printf("515 Invalid address family");
+        break;
+      case STT_BADSAMPLE:
+        printf("516 Sample index out of range");
+        break;
+      case STT_BADPKTVERSION:
+        printf("517 Protocol version mismatch");
+        break;
+      case STT_BADPKTLENGTH:
+        printf("518 Packet length mismatch");
+        break;
+      case STT_INACTIVE:
+        printf("519 Client logging is not active in the daemon");
+        break;
+      case STT_INVALIDNAME:
+        printf("521 Invalid name");
+        break;
+      default:
+        printf("520 Got unexpected error from daemon");
+    }
+    printf("\n");
+  }
+  
+  if (status != STT_SUCCESS &&
+      status != STT_ACCESSALLOWED && status != STT_ACCESSDENIED) {
+    return 0;
+  } 
+
+  if (ntohs(reply->reply) != requested_reply) {
+    printf("508 Bad reply from daemon\n");
+    return 0;
+  }
+
+  /* Make sure an unknown response was not requested */
+  assert(PKL_ReplyLength(reply));
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+print_seconds(unsigned long s)
+{
+  unsigned long d;
+
+  if (s == (uint32_t)-1) {
+    printf("   -");
+  } else if (s < 1200) {
+    printf("%4lu", s);
+  } else if (s < 36000) {
+    printf("%3lum", s / 60);
+  } else if (s < 345600) {
+    printf("%3luh", s / 3600);
+  } else {
+    d = s / 86400;
+    if (d > 999) {
+      printf("%3luy", d / 365);
+    } else {
+      printf("%3lud", d);
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+print_nanoseconds(double s)
+{
+  s = fabs(s);
+
+  if (s < 9999.5e-9) {
+    printf("%4.0fns", s * 1e9);
+  } else if (s < 9999.5e-6) {
+    printf("%4.0fus", s * 1e6);
+  } else if (s < 9999.5e-3) {
+    printf("%4.0fms", s * 1e3);
+  } else if (s < 999.5) {
+    printf("%5.1fs", s);
+  } else if (s < 99999.5) {
+    printf("%5.0fs", s);
+  } else if (s < 99999.5 * 60) {
+    printf("%5.0fm", s / 60);
+  } else if (s < 99999.5 * 3600) {
+    printf("%5.0fh", s / 3600);
+  } else if (s < 99999.5 * 3600 * 24) {
+    printf("%5.0fd", s / (3600 * 24));
+  } else {
+    printf("%5.0fy", s / (3600 * 24 * 365));
+  }
+}
+
+/* ================================================== */
+
+static void
+print_signed_nanoseconds(double s)
+{
+  double x;
+
+  x = fabs(s);
+
+  if (x < 9999.5e-9) {
+    printf("%+5.0fns", s * 1e9);
+  } else if (x < 9999.5e-6) {
+    printf("%+5.0fus", s * 1e6);
+  } else if (x < 9999.5e-3) {
+    printf("%+5.0fms", s * 1e3);
+  } else if (x < 999.5) {
+    printf("%+6.1fs", s);
+  } else if (x < 99999.5) {
+    printf("%+6.0fs", s);
+  } else if (x < 99999.5 * 60) {
+    printf("%+6.0fm", s / 60);
+  } else if (x < 99999.5 * 3600) {
+    printf("%+6.0fh", s / 3600);
+  } else if (x < 99999.5 * 3600 * 24) {
+    printf("%+6.0fd", s / (3600 * 24));
+  } else {
+    printf("%+6.0fy", s / (3600 * 24 * 365));
+  }
+}
+
+/* ================================================== */
+
+static void
+print_freq_ppm(double f)
+{
+  if (fabs(f) < 99999.5) {
+    printf("%10.3f", f);
+  } else {
+    printf("%10.0f", f);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_signed_freq_ppm(double f)
+{
+  if (fabs(f) < 99999.5) {
+    printf("%+10.3f", f);
+  } else {
+    printf("%+10.0f", f);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_clientlog_interval(int rate)
+{
+  if (rate >= 127) {
+    printf(" -");
+  } else {
+    printf("%2d", rate);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_header(const char *header)
+{
+  int len;
+
+  if (csv_mode)
+    return;
+
+  printf("%s\n", header);
+
+  len = strlen(header);
+  while (len--)
+    printf("=");
+  printf("\n");
+}
+
+/* ================================================== */
+
+#define REPORT_END 0x1234
+
+/* Print a report. The syntax of the format is similar to printf(), but not all
+   specifiers are supported and some are different! */
+
+static void
+print_report(const char *format, ...)
+{
+  char buf[256];
+  va_list ap;
+  int i, field, sign, width, prec, spec;
+  const char *string;
+  unsigned long long_uinteger;
+  unsigned int uinteger;
+  int integer;
+  struct timespec *ts;
+  struct tm *tm;
+  double dbl;
+
+  va_start(ap, format);
+
+  for (field = 0; ; field++) {
+    /* Search for text between format specifiers and print it
+       if not in the CSV mode */
+    for (i = 0; i < sizeof (buf) && format[i] != '%' && format[i] != '\0'; i++)
+      buf[i] = format[i];
+
+    if (i >= sizeof (buf))
+      break;
+
+    buf[i] = '\0';
+
+    if (!csv_mode)
+      printf("%s", buf);
+
+    if (format[i] == '\0' || format[i + 1] == '\0')
+      break;
+
+    format += i + 1;
+
+    sign = 0;
+    width = 0;
+    prec = 5;
+
+    if (*format == '+' || *format == '-') {
+      sign = 1;
+      format++;
+    }
+
+    if (isdigit((unsigned char)*format)) {
+      width = atoi(format);
+      while (isdigit((unsigned char)*format))
+        format++;
+    }
+
+    if (*format == '.') {
+      format++;
+      prec = atoi(format);
+      while (isdigit((unsigned char)*format))
+        format++;
+    }
+
+    spec = *format;
+    format++;
+
+    /* Disable human-readable formatting in the CSV mode */
+    if (csv_mode) {
+      sign = width = 0;
+
+      if (field > 0)
+        printf(",");
+
+      switch (spec) {
+        case 'C':
+          spec = 'd';
+          break;
+        case 'F':
+        case 'P':
+          prec = 3;
+          spec = 'f';
+          break;
+        case 'O':
+        case 'S':
+          prec = 9;
+          spec = 'f';
+          break;
+        case 'I':
+          spec = 'U';
+          break;
+        case 'T':
+          spec = 'V';
+          break;
+      }
+    }
+
+    switch (spec) {
+      case 'B': /* boolean */
+        integer = va_arg(ap, int);
+        printf("%s", integer ? "Yes" : "No");
+        break;
+      case 'C': /* clientlog interval */
+        integer = va_arg(ap, int);
+        print_clientlog_interval(integer);
+        break;
+      case 'F': /* absolute frequency in ppm with fast/slow keyword */
+      case 'O': /* absolute offset in seconds with fast/slow keyword */
+        dbl = va_arg(ap, double);
+        printf("%*.*f %s %s", width, prec, fabs(dbl),
+               spec == 'O' ? "seconds" : "ppm",
+               (dbl > 0.0) ^ (spec != 'O') ? "slow" : "fast");
+        break;
+      case 'I': /* interval with unit */
+        long_uinteger = va_arg(ap, unsigned long);
+        print_seconds(long_uinteger);
+        break;
+      case 'L': /* leap status */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case LEAP_Normal:
+            string = width != 1 ? "Normal" : "N";
+            break;
+          case LEAP_InsertSecond:
+            string = width != 1 ? "Insert second" : "+";
+            break;
+          case LEAP_DeleteSecond:
+            string = width != 1 ? "Delete second" : "-";
+            break;
+          case LEAP_Unsynchronised:
+            string = width != 1 ? "Not synchronised" : "?";
+            break;
+          default:
+            string = width != 1 ? "Invalid" : "?";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'M': /* NTP mode */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case MODE_ACTIVE:
+            string = "Symmetric active";
+            break;
+          case MODE_PASSIVE:
+            string = "Symmetric passive";
+            break;
+          case MODE_SERVER:
+            string = "Server";
+            break;
+          default:
+            string = "Invalid";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'N': /* Timestamp source */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case 'D':
+            string = "Daemon";
+            break;
+          case 'K':
+            string = "Kernel";
+            break;
+          case 'H':
+            string = "Hardware";
+            break;
+          default:
+            string = "Invalid";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'P': /* frequency in ppm */
+        dbl = va_arg(ap, double);
+        if (sign)
+          print_signed_freq_ppm(dbl);
+        else
+          print_freq_ppm(dbl);
+        break;
+      case 'R': /* reference ID in hexdecimal */
+        long_uinteger = va_arg(ap, unsigned long);
+        printf("%08lX", long_uinteger);
+        break;
+      case 'S': /* offset with unit */
+        dbl = va_arg(ap, double);
+        if (sign)
+          print_signed_nanoseconds(dbl);
+        else
+          print_nanoseconds(dbl);
+        break;
+      case 'T': /* timespec as date and time in UTC */
+        ts = va_arg(ap, struct timespec *);
+        tm = gmtime(&ts->tv_sec);
+        if (!tm)
+          break;
+        strftime(buf, sizeof (buf), "%a %b %d %T %Y", tm);
+        printf("%s", buf);
+        break;
+      case 'U': /* unsigned long in decimal */
+        long_uinteger = va_arg(ap, unsigned long);
+        printf("%*lu", width, long_uinteger);
+        break;
+      case 'V': /* timespec as seconds since epoch */
+        ts = va_arg(ap, struct timespec *);
+        printf("%s", UTI_TimespecToString(ts));
+        break;
+      case 'b': /* unsigned int in binary */
+        uinteger = va_arg(ap, unsigned int);
+        for (i = prec - 1; i >= 0; i--)
+          printf("%c", uinteger & 1U << i ? '1' : '0');
+        break;
+
+      /* Classic printf specifiers */
+      case 'c': /* character */
+        integer = va_arg(ap, int);
+        printf("%c", integer);
+        break;
+      case 'd': /* signed int in decimal */
+        integer = va_arg(ap, int);
+        printf("%*d", width, integer);
+        break;
+      case 'f': /* double */
+        dbl = va_arg(ap, double);
+        printf(sign ? "%+*.*f" : "%*.*f", width, prec, dbl);
+        break;
+      case 'o': /* unsigned int in octal */
+        uinteger = va_arg(ap, unsigned int);
+        printf("%*o", width, uinteger);
+        break;
+      case 's': /* string */
+        string = va_arg(ap, const char *);
+        if (sign)
+          printf("%-*s", width, string);
+        else
+          printf("%*s", width, string);
+        break;
+      case 'u': /* unsigned int in decimal */
+        uinteger = va_arg(ap, unsigned int);
+        printf("%*u", width, uinteger);
+        break;
+    }
+  }
+
+  /* Require terminating argument to catch bad type conversions */
+  if (va_arg(ap, int) != REPORT_END)
+    assert(0);
+
+  va_end(ap);
+
+  if (csv_mode)
+    printf("\n");
+}
+
+/* ================================================== */
+
+static void
+print_info_field(const char *format, ...)
+{
+  va_list ap;
+
+  if (csv_mode)
+    return;
+
+  va_start(ap, format);
+  vprintf(format, ap);
+  va_end(ap);
+}
+
+/* ================================================== */
+
+static int
+get_source_name(IPAddr *ip_addr, char *buf, int size)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  int i;
+
+  request.command = htons(REQ_NTP_SOURCE_NAME);
+  UTI_IPHostToNetwork(ip_addr, &request.data.ntp_source_name.ip_addr);
+  if (!request_reply(&request, &reply, RPY_NTP_SOURCE_NAME, 0) ||
+      reply.data.ntp_source_name.name[sizeof (reply.data.ntp_source_name.name) - 1] != '\0' ||
+      snprintf(buf, size, "%s", (char *)reply.data.ntp_source_name.name) >= size)
+    return 0;
+
+  /* Make sure the name is printable */
+  for (i = 0; i < size && buf[i] != '\0'; i++) {
+    if (!isgraph((unsigned char)buf[i]))
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+format_name(char *buf, int size, int trunc_dns, int ref, uint32_t ref_id,
+            int source, IPAddr *ip_addr)
+{
+  if (ref) {
+    snprintf(buf, size, "%s", UTI_RefidToString(ref_id));
+  } else if (source && source_names) {
+    if (!get_source_name(ip_addr, buf, size))
+      snprintf(buf, size, "?");
+  } else if (no_dns || csv_mode) {
+    snprintf(buf, size, "%s", UTI_IPToString(ip_addr));
+  } else {
+    DNS_IPAddress2Name(ip_addr, buf, size);
+    if (trunc_dns > 0 && strlen(buf) > trunc_dns) {
+      buf[trunc_dns - 1] = '>';
+      buf[trunc_dns] = '\0';
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_sources_options(char *line, int *all, int *verbose)
+{
+  char *opt;
+
+  *all = *verbose = 0;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (!strcmp(opt, "-a"))
+      *all = 1;
+    else if (!strcmp(opt, "-v"))
+      *verbose = !csv_mode;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sourcename(char *line)
+{
+  IPAddr ip_addr;
+  char name[256];
+
+  if (!parse_source_address(line, &ip_addr)) {
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+
+  if (!get_source_name(&ip_addr, name, sizeof (name)))
+    return 0;
+
+  print_report("%s\n", name, REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sources(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t i, mode, n_sources;
+  char name[256], mode_ch, state_ch;
+  int all, verbose;
+
+  parse_sources_options(line, &all, &verbose);
+  
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf("\n");
+    printf("  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.\n");
+    printf(" / .- Source state '*' = current best, '+' = combined, '-' = not combined,\n");
+    printf("| /             'x' = may be in error, '~' = too variable, '?' = unusable.\n");
+    printf("||                                                 .- xxxx [ yyyy ] +/- zzzz\n");
+    printf("||      Reachability register (octal) -.           |  xxxx = adjusted offset,\n");
+    printf("||      Log2(Polling interval) --.      |          |  yyyy = measured offset,\n");
+    printf("||                                \\     |          |  zzzz = estimated error.\n");
+    printf("||                                 |    |           \\\n");
+  }
+
+  print_header("MS Name/IP address         Stratum Poll Reach LastRx Last sample               ");
+
+  /*           "MS NNNNNNNNNNNNNNNNNNNNNNNNNNN  SS  PP   RRR  RRRR  SSSSSSS[SSSSSSS] +/- SSSSSS" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCE_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+      return 0;
+
+    mode = ntohs(reply.data.source_data.mode);
+    UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    format_name(name, sizeof (name), 25,
+                mode == RPY_SD_MD_REF && ip_addr.family == IPADDR_INET4,
+                ip_addr.addr.in4, 1, &ip_addr);
+
+    switch (mode) {
+      case RPY_SD_MD_CLIENT:
+        mode_ch = '^';
+        break;
+      case RPY_SD_MD_PEER:
+        mode_ch = '=';
+        break;
+      case RPY_SD_MD_REF:
+        mode_ch = '#';
+        break;
+      default:
+        mode_ch = ' ';
+    }
+
+    switch (ntohs(reply.data.source_data.state)) {
+      case RPY_SD_ST_SELECTED:
+        state_ch = '*';
+        break;
+      case RPY_SD_ST_NONSELECTABLE:
+        state_ch = '?';
+        break;
+      case RPY_SD_ST_FALSETICKER:
+        state_ch = 'x';
+        break;
+      case RPY_SD_ST_JITTERY:
+        state_ch = '~';
+        break;
+      case RPY_SD_ST_UNSELECTED:
+        state_ch = '+';
+        break;
+      case RPY_SD_ST_SELECTABLE:
+        state_ch = '-';
+        break;
+      default:
+        state_ch = ' ';
+    }
+
+    switch (ntohs(reply.data.source_data.flags)) {
+      default:
+        break;
+    }
+
+    print_report("%c%c %-27s  %2d  %2d   %3o  %I  %+S[%+S] +/- %S\n",
+                 mode_ch, state_ch, name,
+                 ntohs(reply.data.source_data.stratum),
+                 (int16_t)ntohs(reply.data.source_data.poll),
+                 ntohs(reply.data.source_data.reachability),
+                 (unsigned long)ntohl(reply.data.source_data.since_sample),
+                 UTI_FloatNetworkToHost(reply.data.source_data.latest_meas),
+                 UTI_FloatNetworkToHost(reply.data.source_data.orig_latest_meas),
+                 UTI_FloatNetworkToHost(reply.data.source_data.latest_meas_err),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sourcestats(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_sources;
+  int all, verbose;
+  char name[256];
+  IPAddr ip_addr;
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf("                             .- Number of sample points in measurement set.\n");
+    printf("                            /    .- Number of residual runs with same sign.\n");
+    printf("                           |    /    .- Length of measurement set (time).\n");
+    printf("                           |   |    /      .- Est. clock freq error (ppm).\n");
+    printf("                           |   |   |      /           .- Est. error in freq.\n");
+    printf("                           |   |   |     |           /         .- Est. offset.\n");
+    printf("                           |   |   |     |          |          |   On the -.\n");
+    printf("                           |   |   |     |          |          |   samples. \\\n");
+    printf("                           |   |   |     |          |          |             |\n");
+  }
+
+  print_header("Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev");
+
+  /*           "NNNNNNNNNNNNNNNNNNNNNNNNN  NP  NR  SSSS FFFFFFFFFF SSSSSSSSSS  SSSSSSS  SSSSSS" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCESTATS);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCESTATS, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.sourcestats.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    format_name(name, sizeof (name), 25, ip_addr.family == IPADDR_UNSPEC,
+                ntohl(reply.data.sourcestats.ref_id), 1, &ip_addr);
+
+    print_report("%-25s %3U %3U  %I %+P %P  %+S  %S\n",
+                 name,
+                 (unsigned long)ntohl(reply.data.sourcestats.n_samples),
+                 (unsigned long)ntohl(reply.data.sourcestats.n_runs),
+                 (unsigned long)ntohl(reply.data.sourcestats.span_seconds),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.resid_freq_ppm),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.skew_ppm),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.est_offset),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.sd),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_tracking(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t ref_id;
+  char name[256];
+  struct timespec ref_time;
+  
+  request.command = htons(REQ_TRACKING);
+  if (!request_reply(&request, &reply, RPY_TRACKING, 0))
+    return 0;
+
+  ref_id = ntohl(reply.data.tracking.ref_id);
+
+  UTI_IPNetworkToHost(&reply.data.tracking.ip_addr, &ip_addr);
+  format_name(name, sizeof (name), sizeof (name),
+              ip_addr.family == IPADDR_UNSPEC, ref_id, 1, &ip_addr);
+
+  UTI_TimespecNetworkToHost(&reply.data.tracking.ref_time, &ref_time);
+
+  print_report("Reference ID    : %R (%s)\n"
+               "Stratum         : %u\n"
+               "Ref time (UTC)  : %T\n"
+               "System time     : %.9O of NTP time\n"
+               "Last offset     : %+.9f seconds\n"
+               "RMS offset      : %.9f seconds\n"
+               "Frequency       : %.3F\n"
+               "Residual freq   : %+.3f ppm\n"
+               "Skew            : %.3f ppm\n"
+               "Root delay      : %.9f seconds\n"
+               "Root dispersion : %.9f seconds\n"
+               "Update interval : %.1f seconds\n"
+               "Leap status     : %L\n",
+               (unsigned long)ref_id, name,
+               ntohs(reply.data.tracking.stratum),
+               &ref_time,
+               UTI_FloatNetworkToHost(reply.data.tracking.current_correction),
+               UTI_FloatNetworkToHost(reply.data.tracking.last_offset),
+               UTI_FloatNetworkToHost(reply.data.tracking.rms_offset),
+               UTI_FloatNetworkToHost(reply.data.tracking.freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.resid_freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.skew_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.root_delay),
+               UTI_FloatNetworkToHost(reply.data.tracking.root_dispersion),
+               UTI_FloatNetworkToHost(reply.data.tracking.last_update_interval),
+               ntohs(reply.data.tracking.leap_status), REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_authdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t i, source_mode, n_sources;
+  int all, verbose;
+  const char *mode_str;
+  char name[256];
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf(    "                             .- Auth. mechanism (NTS, SK - symmetric key)\n");
+    printf(    "                            |   Key length -.  Cookie length (bytes) -.\n");
+    printf(    "                            |       (bits)  |  Num. of cookies --.    |\n");
+    printf(    "                            |               |  Key est. attempts  |   |\n");
+    printf(    "                            |               |           |         |   |\n");
+  }
+
+  print_header("Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen");
+
+  /*           "NNNNNNNNNNNNNNNNNNNNNNNNNNN MMMM KKKKK AAAA LLLL LLLL AAAA NNNN CCCC LLLL" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCE_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+      return 0;
+
+    source_mode = ntohs(reply.data.source_data.mode);
+    if (source_mode != RPY_SD_MD_CLIENT && source_mode != RPY_SD_MD_PEER)
+      continue;
+
+    UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    request.command = htons(REQ_AUTH_DATA);
+    request.data.auth_data.ip_addr = reply.data.source_data.ip_addr;
+    if (!request_reply(&request, &reply, RPY_AUTH_DATA, 0))
+      return 0;
+
+    format_name(name, sizeof (name), 25, 0, 0, 1, &ip_addr);
+
+    switch (ntohs(reply.data.auth_data.mode)) {
+      case RPY_AD_MD_NONE:
+        mode_str = "-";
+        break;
+      case RPY_AD_MD_SYMMETRIC:
+        mode_str = "SK";
+        break;
+      case RPY_AD_MD_NTS:
+        mode_str = "NTS";
+        break;
+      default:
+        mode_str = "?";
+        break;
+    }
+
+    print_report("%-27s %4s %5U %4d %4d %I %4d %4d %4d %4d\n",
+                 name, mode_str,
+                 (unsigned long)ntohl(reply.data.auth_data.key_id),
+                 ntohs(reply.data.auth_data.key_type),
+                 ntohs(reply.data.auth_data.key_length),
+                 (unsigned long)ntohl(reply.data.auth_data.last_ke_ago),
+                 ntohs(reply.data.auth_data.ke_attempts),
+                 ntohs(reply.data.auth_data.nak),
+                 ntohs(reply.data.auth_data.cookies),
+                 ntohs(reply.data.auth_data.cookie_length),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_ntpdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr remote_addr, local_addr;
+  struct timespec ref_time;
+  uint32_t i, n_sources;
+  uint16_t mode;
+  int specified_addr;
+
+  if (*line) {
+    specified_addr = 1;
+    n_sources = 1;
+  } else {
+    specified_addr = 0;
+    request.command = htons(REQ_N_SOURCES);
+    if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+      return 0;
+    n_sources = ntohl(reply.data.n_sources.n_sources);
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    if (specified_addr) {
+      if (!parse_source_address(line, &remote_addr)) {
+        LOG(LOGS_ERR, "Could not get address for hostname");
+        return 0;
+      }
+    } else {
+      request.command = htons(REQ_SOURCE_DATA);
+      request.data.source_data.index = htonl(i);
+      if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+        return 0;
+
+      mode = ntohs(reply.data.source_data.mode);
+      if (mode != RPY_SD_MD_CLIENT && mode != RPY_SD_MD_PEER)
+        continue;
+
+      UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &remote_addr);
+      if (!UTI_IsIPReal(&remote_addr))
+        continue;
+    }
+
+    request.command = htons(REQ_NTP_DATA);
+    UTI_IPHostToNetwork(&remote_addr, &request.data.ntp_data.ip_addr);
+    if (!request_reply(&request, &reply, RPY_NTP_DATA, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.ntp_data.remote_addr, &remote_addr);
+    UTI_IPNetworkToHost(&reply.data.ntp_data.local_addr, &local_addr);
+    UTI_TimespecNetworkToHost(&reply.data.ntp_data.ref_time, &ref_time);
+
+    if (!specified_addr && !csv_mode)
+      printf("\n");
+
+    print_report("Remote address  : %s (%R)\n"
+                 "Remote port     : %u\n"
+                 "Local address   : %s (%R)\n"
+                 "Leap status     : %L\n"
+                 "Version         : %u\n"
+                 "Mode            : %M\n"
+                 "Stratum         : %u\n"
+                 "Poll interval   : %d (%.0f seconds)\n"
+                 "Precision       : %d (%.9f seconds)\n"
+                 "Root delay      : %.6f seconds\n"
+                 "Root dispersion : %.6f seconds\n"
+                 "Reference ID    : %R (%s)\n"
+                 "Reference time  : %T\n"
+                 "Offset          : %+.9f seconds\n"
+                 "Peer delay      : %.9f seconds\n"
+                 "Peer dispersion : %.9f seconds\n"
+                 "Response time   : %.9f seconds\n"
+                 "Jitter asymmetry: %+.2f\n"
+                 "NTP tests       : %.3b %.3b %.4b\n"
+                 "Interleaved     : %B\n"
+                 "Authenticated   : %B\n"
+                 "TX timestamping : %N\n"
+                 "RX timestamping : %N\n"
+                 "Total TX        : %U\n"
+                 "Total RX        : %U\n"
+                 "Total valid RX  : %U\n"
+                 "Total good RX   : %U\n",
+                 UTI_IPToString(&remote_addr), (unsigned long)UTI_IPToRefid(&remote_addr),
+                 ntohs(reply.data.ntp_data.remote_port),
+                 UTI_IPToString(&local_addr), (unsigned long)UTI_IPToRefid(&local_addr),
+                 reply.data.ntp_data.leap, reply.data.ntp_data.version,
+                 reply.data.ntp_data.mode, reply.data.ntp_data.stratum,
+                 reply.data.ntp_data.poll, UTI_Log2ToDouble(reply.data.ntp_data.poll),
+                 reply.data.ntp_data.precision, UTI_Log2ToDouble(reply.data.ntp_data.precision),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.root_delay),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.root_dispersion),
+                 (unsigned long)ntohl(reply.data.ntp_data.ref_id),
+                 reply.data.ntp_data.stratum <= 1 ?
+                   UTI_RefidToString(ntohl(reply.data.ntp_data.ref_id)) : "",
+                 &ref_time,
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.offset),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.peer_delay),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.peer_dispersion),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.response_time),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.jitter_asymmetry),
+                 ntohs(reply.data.ntp_data.flags) >> 7,
+                 ntohs(reply.data.ntp_data.flags) >> 4,
+                 ntohs(reply.data.ntp_data.flags),
+                 ntohs(reply.data.ntp_data.flags) & RPY_NTP_FLAG_INTERLEAVED,
+                 ntohs(reply.data.ntp_data.flags) & RPY_NTP_FLAG_AUTHENTICATED,
+                 reply.data.ntp_data.tx_tss_char, reply.data.ntp_data.rx_tss_char,
+                 (unsigned long)ntohl(reply.data.ntp_data.total_tx_count),
+                 (unsigned long)ntohl(reply.data.ntp_data.total_rx_count),
+                 (unsigned long)ntohl(reply.data.ntp_data.total_valid_count),
+                 (unsigned long)ntohl(reply.data.ntp_data.total_good_count),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_selectdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_sources;
+  int all, verbose, conf_options, eff_options;
+  char name[256];
+  IPAddr ip_addr;
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf(    "  . State: N - noselect, s - unsynchronised, M - missing samples,\n");
+    printf(    " /         d/D - large distance, ~ - jittery, w/W - waits for others,\n");
+    printf(    "|          S - stale, O - orphan, T - not trusted, P - not preferred,\n");
+    printf(    "|          U - waits for update,, x - falseticker, + - combined, * - best.\n");
+    printf(    "|   Effective options   ---------.  (N - noselect, P - prefer\n");
+    printf(    "|   Configured options  ----.     \\  T - trust, R - require)\n");
+    printf(    "|   Auth. enabled (Y/N) -.   \\     \\     Offset interval --.\n");
+    printf(    "|                        |    |     |                       |\n");
+  }
+
+  print_header("S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap");
+
+  /*           "S NNNNNNNNNNNNNNNNNNNNNNNNN A OOOO- OOOO- LLLL SSSSS IIIIIII IIIIIII  L" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SELECT_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SELECT_DATA, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.select_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    format_name(name, sizeof (name), 25, ip_addr.family == IPADDR_UNSPEC,
+                ntohl(reply.data.select_data.ref_id), 1, &ip_addr);
+
+    conf_options = ntohs(reply.data.select_data.conf_options);
+    eff_options = ntohs(reply.data.select_data.eff_options);
+
+    print_report("%c %-25s %c %c%c%c%c%c %c%c%c%c%c %I %5.1f %+S %+S  %1L\n",
+                 reply.data.select_data.state_char,
+                 name,
+                 reply.data.select_data.authentication ? 'Y' : 'N',
+                 conf_options & RPY_SD_OPTION_NOSELECT ? 'N' : '-',
+                 conf_options & RPY_SD_OPTION_PREFER ? 'P' : '-',
+                 conf_options & RPY_SD_OPTION_TRUST ? 'T' : '-',
+                 conf_options & RPY_SD_OPTION_REQUIRE ? 'R' : '-',
+                 '-',
+                 eff_options & RPY_SD_OPTION_NOSELECT ? 'N' : '-',
+                 eff_options & RPY_SD_OPTION_PREFER ? 'P' : '-',
+                 eff_options & RPY_SD_OPTION_TRUST ? 'T' : '-',
+                 eff_options & RPY_SD_OPTION_REQUIRE ? 'R' : '-',
+                 '-',
+                 (unsigned long)ntohl(reply.data.select_data.last_sample_ago),
+                 UTI_FloatNetworkToHost(reply.data.select_data.score),
+                 UTI_FloatNetworkToHost(reply.data.select_data.lo_limit),
+                 UTI_FloatNetworkToHost(reply.data.select_data.hi_limit),
+                 reply.data.select_data.leap,
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_serverstats(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+
+  request.command = htons(REQ_SERVER_STATS);
+  if (!request_reply(&request, &reply, RPY_SERVER_STATS3, 0))
+    return 0;
+
+  print_report("NTP packets received       : %U\n"
+               "NTP packets dropped        : %U\n"
+               "Command packets received   : %U\n"
+               "Command packets dropped    : %U\n"
+               "Client log records dropped : %U\n"
+               "NTS-KE connections accepted: %U\n"
+               "NTS-KE connections dropped : %U\n"
+               "Authenticated NTP packets  : %U\n"
+               "Interleaved NTP packets    : %U\n"
+               "NTP timestamps held        : %U\n"
+               "NTP timestamp span         : %U\n",
+               (unsigned long)ntohl(reply.data.server_stats.ntp_hits),
+               (unsigned long)ntohl(reply.data.server_stats.ntp_drops),
+               (unsigned long)ntohl(reply.data.server_stats.cmd_hits),
+               (unsigned long)ntohl(reply.data.server_stats.cmd_drops),
+               (unsigned long)ntohl(reply.data.server_stats.log_drops),
+               (unsigned long)ntohl(reply.data.server_stats.nke_hits),
+               (unsigned long)ntohl(reply.data.server_stats.nke_drops),
+               (unsigned long)ntohl(reply.data.server_stats.ntp_auth_hits),
+               (unsigned long)ntohl(reply.data.server_stats.ntp_interleaved_hits),
+               (unsigned long)ntohl(reply.data.server_stats.ntp_timestamps),
+               (unsigned long)ntohl(reply.data.server_stats.ntp_span_seconds),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_smoothing(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t flags;
+
+  request.command = htons(REQ_SMOOTHING);
+  if (!request_reply(&request, &reply, RPY_SMOOTHING, 0))
+    return 0;
+
+  flags = ntohl(reply.data.smoothing.flags);
+
+  print_report("Active         : %B %s\n"
+               "Offset         : %+.9f seconds\n"
+               "Frequency      : %+.6f ppm\n"
+               "Wander         : %+.6f ppm per second\n"
+               "Last update    : %.1f seconds ago\n"
+               "Remaining time : %.1f seconds\n",
+               !!(flags & RPY_SMT_FLAG_ACTIVE),
+               flags & RPY_SMT_FLAG_LEAPONLY ? "(leap second only)" : "",
+               UTI_FloatNetworkToHost(reply.data.smoothing.offset),
+               UTI_FloatNetworkToHost(reply.data.smoothing.freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.smoothing.wander_ppm),
+               UTI_FloatNetworkToHost(reply.data.smoothing.last_update_ago),
+               UTI_FloatNetworkToHost(reply.data.smoothing.remaining_time),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_smoothtime(CMD_Request *msg, const char *line)
+{
+  if (!strcmp(line, "reset")) {
+    msg->data.smoothtime.option = htonl(REQ_SMOOTHTIME_RESET);
+  } else if (!strcmp(line, "activate")) {
+    msg->data.smoothtime.option = htonl(REQ_SMOOTHTIME_ACTIVATE);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for smoothtime command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_SMOOTHTIME);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_rtcreport(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  struct timespec ref_time;
+  
+  request.command = htons(REQ_RTCREPORT);
+  if (!request_reply(&request, &reply, RPY_RTC, 0))
+    return 0;
+
+  UTI_TimespecNetworkToHost(&reply.data.rtc.ref_time, &ref_time);
+
+  print_report("RTC ref time (UTC) : %T\n"
+               "Number of samples  : %u\n"
+               "Number of runs     : %u\n"
+               "Sample span period : %I\n"
+               "RTC is fast by     : %12.6f seconds\n"
+               "RTC gains time at  : %9.3f ppm\n",
+               &ref_time,
+               ntohs(reply.data.rtc.n_samples),
+               ntohs(reply.data.rtc.n_runs),
+               (unsigned long)ntohl(reply.data.rtc.span_seconds),
+               UTI_FloatNetworkToHost(reply.data.rtc.rtc_seconds_fast),
+               UTI_FloatNetworkToHost(reply.data.rtc.rtc_gain_rate_ppm),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_clients(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip;
+  uint32_t i, n_clients, next_index, n_indices, min_hits, reset;
+  RPY_ClientAccesses_Client *client;
+  char header[80], name[50], *opt, *arg;
+  int nke;
+
+  next_index = 0;
+  min_hits = 0;
+  reset = 0;
+  nke = 0;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (strcmp(opt, "-k") == 0) {
+      nke = 1;
+    } else if (strcmp(opt, "-p") == 0) {
+      arg = line;
+      line = CPS_SplitWord(line);
+      if (sscanf(arg, "%"SCNu32, &min_hits) != 1) {
+        LOG(LOGS_ERR, "Invalid syntax for clients command");
+        return 0;
+      }
+    } else if (strcmp(opt, "-r") == 0) {
+      reset = 1;
+    }
+  }
+
+  snprintf(header, sizeof (header),
+           "Hostname                      NTP   Drop Int IntL Last  %6s   Drop Int  Last",
+           nke ? "NTS-KE" : "Cmd");
+  print_header(header);
+
+  while (1) {
+    request.command = htons(REQ_CLIENT_ACCESSES_BY_INDEX3);
+    request.data.client_accesses_by_index.first_index = htonl(next_index);
+    request.data.client_accesses_by_index.n_clients = htonl(MAX_CLIENT_ACCESSES);
+    request.data.client_accesses_by_index.min_hits = htonl(min_hits);
+    request.data.client_accesses_by_index.reset = htonl(reset);
+
+    if (!request_reply(&request, &reply, RPY_CLIENT_ACCESSES_BY_INDEX3, 0))
+      return 0;
+
+    n_clients = ntohl(reply.data.client_accesses_by_index.n_clients);
+    n_indices = ntohl(reply.data.client_accesses_by_index.n_indices);
+
+    for (i = 0; i < n_clients && i < MAX_CLIENT_ACCESSES; i++) {
+      client = &reply.data.client_accesses_by_index.clients[i];
+
+      UTI_IPNetworkToHost(&client->ip, &ip);
+
+      /* UNSPEC means the record could not be found in the daemon's tables.
+         We shouldn't ever generate this case, but ignore it if we do. */
+      if (ip.family == IPADDR_UNSPEC)
+        continue;
+
+      format_name(name, sizeof (name), 25, 0, 0, 0, &ip);
+
+      print_report("%-25s  %6U  %5U  %C  %C  %I  %6U  %5U  %C  %I\n",
+                   name,
+                   (unsigned long)ntohl(client->ntp_hits),
+                   (unsigned long)ntohl(client->ntp_drops),
+                   client->ntp_interval,
+                   client->ntp_timeout_interval,
+                   (unsigned long)ntohl(client->last_ntp_hit_ago),
+                   (unsigned long)ntohl(nke ? client->nke_hits : client->cmd_hits),
+                   (unsigned long)ntohl(nke ? client->nke_drops : client->cmd_drops),
+                   nke ? client->nke_interval : client->cmd_interval,
+                   (unsigned long)ntohl(nke ? client->last_nke_hit_ago :
+                                              client->last_cmd_hit_ago),
+                   REPORT_END);
+    }
+
+    /* Set the next index to probe based on what the server tells us */
+    next_index = ntohl(reply.data.client_accesses_by_index.next_index);
+
+    if (next_index >= n_indices || n_clients < MAX_CLIENT_ACCESSES)
+      break;
+  }
+
+  return 1;
+}
+
+
+/* ================================================== */
+/* Process the manual list command */
+static int
+process_cmd_manual_list(const char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_samples;
+  RPY_ManualListSample *sample;
+  struct timespec when;
+
+  request.command = htons(REQ_MANUAL_LIST);
+  if (!request_reply(&request, &reply, RPY_MANUAL_LIST2, 0))
+    return 0;
+
+  n_samples = ntohl(reply.data.manual_list.n_samples);
+  print_info_field("210 n_samples = %lu\n", (unsigned long)n_samples);
+
+  print_header("#    Date     Time(UTC)    Slewed   Original   Residual");
+
+  for (i = 0; i < n_samples && i < MAX_MANUAL_LIST_SAMPLES; i++) {
+    sample = &reply.data.manual_list.samples[i];
+    UTI_TimespecNetworkToHost(&sample->when, &when);
+
+    print_report("%2d %s %10.2f %10.2f %10.2f\n",
+                 i, UTI_TimeToLogForm(when.tv_sec),
+                 UTI_FloatNetworkToHost(sample->slewed_offset),
+                 UTI_FloatNetworkToHost(sample->orig_offset),
+                 UTI_FloatNetworkToHost(sample->residual),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_manual_delete(CMD_Request *msg, const char *line)
+{
+  int index;
+
+  if (sscanf(line, "%d", &index) != 1) {
+    LOG(LOGS_ERR, "Bad syntax for manual delete command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_MANUAL_DELETE);
+  msg->data.manual_delete.index = htonl(index);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_settime(char *line)
+{
+  struct timespec ts;
+  time_t now, new_time;
+  CMD_Request request;
+  CMD_Reply reply;
+  double dfreq_ppm, new_afreq_ppm;
+  double offset;
+
+  now = time(NULL);
+  new_time = get_date(line, &now);
+
+  if (new_time == -1) {
+    printf("510 - Could not parse date string\n");
+  } else {
+    ts.tv_sec = new_time;
+    ts.tv_nsec = 0;
+    UTI_TimespecHostToNetwork(&ts, &request.data.settime.ts);
+    request.command = htons(REQ_SETTIME);
+    if (request_reply(&request, &reply, RPY_MANUAL_TIMESTAMP2, 1)) {
+          offset = UTI_FloatNetworkToHost(reply.data.manual_timestamp.offset);
+          dfreq_ppm = UTI_FloatNetworkToHost(reply.data.manual_timestamp.dfreq_ppm);
+          new_afreq_ppm = UTI_FloatNetworkToHost(reply.data.manual_timestamp.new_afreq_ppm);
+          printf("Clock was %.2f seconds fast.  Frequency change = %.2fppm, new frequency = %.2fppm\n",
+              offset, dfreq_ppm, new_afreq_ppm);
+          return 1;
+    }
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+process_cmd_rekey(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_REKEY);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_makestep(CMD_Request *msg, char *line)
+{
+  int limit;
+  double threshold;
+
+  if (*line) {
+    if (sscanf(line, "%lf %d", &threshold, &limit) != 2) {
+      LOG(LOGS_ERR, "Bad syntax for makestep command");
+      return 0;
+    }
+    msg->command = htons(REQ_MODIFY_MAKESTEP);
+    msg->data.modify_makestep.limit = htonl(limit);
+    msg->data.modify_makestep.threshold = UTI_FloatHostToNetwork(threshold);
+  } else {
+    msg->command = htons(REQ_MAKESTEP);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_activity(const char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+
+  request.command = htons(REQ_ACTIVITY);
+  if (!request_reply(&request, &reply, RPY_ACTIVITY, 0))
+    return 0;
+
+  print_info_field("200 OK\n");
+
+  print_report("%U sources online\n"
+               "%U sources offline\n"
+               "%U sources doing burst (return to online)\n"
+               "%U sources doing burst (return to offline)\n"
+               "%U sources with unknown address\n",
+               (unsigned long)ntohl(reply.data.activity.online),
+               (unsigned long)ntohl(reply.data.activity.offline),
+               (unsigned long)ntohl(reply.data.activity.burst_online),
+               (unsigned long)ntohl(reply.data.activity.burst_offline),
+               (unsigned long)ntohl(reply.data.activity.unresolved),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reselectdist(CMD_Request *msg, char *line)
+{
+  double dist;
+  int ok;
+  msg->command = htons(REQ_RESELECTDISTANCE);
+  if (sscanf(line, "%lf", &dist) == 1) {
+    msg->data.reselect_distance.distance = UTI_FloatHostToNetwork(dist);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+  return ok;
+}
+
+/* ================================================== */
+
+static void
+process_cmd_reselect(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_RESELECT);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_refresh(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_REFRESH);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_shutdown(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_SHUTDOWN);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reload(CMD_Request *msg, char *line)
+{
+  if (!strcmp(line, "sources")) {
+    msg->command = htons(REQ_RELOAD_SOURCES);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for reload command");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reset(CMD_Request *msg, char *line)
+{
+  if (!strcmp(line, "sources")) {
+    msg->command = htons(REQ_RESET_SOURCES);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for reset command");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_waitsync(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t ref_id;
+  double correction, skew_ppm, max_correction, max_skew_ppm, interval;
+  int ret = 0, max_tries, i;
+  struct timeval timeout;
+
+  max_tries = 0;
+  max_correction = 0.0;
+  max_skew_ppm = 0.0;
+  interval = 10.0;
+
+  if (sscanf(line, "%d %lf %lf %lf", &max_tries, &max_correction, &max_skew_ppm, &interval))
+    ;
+
+  /* Don't allow shorter interval than 0.1 seconds */
+  if (interval < 0.1)
+    interval = 0.1;
+
+  request.command = htons(REQ_TRACKING);
+
+  for (i = 1; ; i++) {
+    if (request_reply(&request, &reply, RPY_TRACKING, 0)) {
+      ref_id = ntohl(reply.data.tracking.ref_id);
+      UTI_IPNetworkToHost(&reply.data.tracking.ip_addr, &ip_addr);
+
+      correction = UTI_FloatNetworkToHost(reply.data.tracking.current_correction);
+      correction = fabs(correction);
+      skew_ppm = UTI_FloatNetworkToHost(reply.data.tracking.skew_ppm);
+
+      print_report("try: %d, refid: %R, correction: %.9f, skew: %.3f\n",
+                   i, (unsigned long)ref_id, correction, skew_ppm, REPORT_END);
+
+      if ((ip_addr.family != IPADDR_UNSPEC ||
+           (ref_id != 0 && ref_id != 0x7f7f0101L /* LOCAL refid */)) &&
+          (max_correction == 0.0 || correction <= max_correction) &&
+          (max_skew_ppm == 0.0 || skew_ppm <= max_skew_ppm)) {
+        ret = 1;
+      }
+    }
+
+    if (!ret && (!max_tries || i < max_tries) && !quit) {
+      UTI_DoubleToTimeval(interval, &timeout);
+      if (select(0, NULL, NULL, NULL, &timeout))
+        break;
+    } else {
+      break;
+    }
+  }
+  return ret;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_dns(const char *line)
+{
+  if (!strcmp(line, "-46")) {
+    DNS_SetAddressFamily(IPADDR_UNSPEC);
+  } else if (!strcmp(line, "-4")) {
+    DNS_SetAddressFamily(IPADDR_INET4);
+  } else if (!strcmp(line, "-6")) {
+    DNS_SetAddressFamily(IPADDR_INET6);
+  } else if (!strcmp(line, "-n")) {
+    no_dns = 1;
+  } else if (!strcmp(line, "+n")) {
+    no_dns = 0;
+  } else {
+    LOG(LOGS_ERR, "Unrecognized dns command");
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_timeout(const char *line)
+{
+  int timeout;
+
+  timeout = atoi(line);
+  if (timeout < 100) {
+    LOG(LOGS_ERR, "Timeout %d is too short", timeout);
+    return 0;
+  }
+  initial_timeout = timeout;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_retries(const char *line)
+{
+  int retries;
+
+  retries = atoi(line);
+  if (retries < 0 || retries > 30) {
+    LOG(LOGS_ERR, "Invalid maximum number of retries");
+    return 0;
+  }
+  max_retries = retries;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_keygen(char *line)
+{
+  unsigned int i, args, cmac_length, length, id = 1, bits = 160;
+  unsigned char key[512];
+  const char *type;
+  char *words[3];
+
+#ifdef FEAT_SECHASH
+  type = "SHA1";
+#else
+  type = "MD5";
+#endif
+
+  args = UTI_SplitString(line, words, 3);
+  if (args >= 2)
+    type = words[1];
+
+  if (args > 3 ||
+      (args >= 1 && sscanf(words[0], "%u", &id) != 1) ||
+      (args >= 3 && sscanf(words[2], "%u", &bits) != 1)) {
+    LOG(LOGS_ERR, "Invalid syntax for keygen command");
+    return 0;
+  }
+
+#ifdef HAVE_CMAC
+  cmac_length = CMC_GetKeyLength(UTI_CmacNameToAlgorithm(type));
+#else
+  cmac_length = 0;
+#endif
+
+  if (HSH_GetHashId(UTI_HashNameToAlgorithm(type)) >= 0) {
+    length = (bits + 7) / 8;
+  } else if (cmac_length > 0) {
+    length = cmac_length;
+  } else {
+    LOG(LOGS_ERR, "Unknown hash function or cipher %s", type);
+    return 0;
+  }
+
+  length = CLAMP(10, length, sizeof (key));
+
+  UTI_GetRandomBytesUrandom(key, length);
+
+  printf("%u %s HEX:", id, type);
+  for (i = 0; i < length; i++)
+    printf("%02hhX", key[i]);
+  printf("\n");
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_line(char *line)
+{
+  char *command;
+  int do_normal_submit;
+  int ret;
+  CMD_Request tx_message;
+  CMD_Reply rx_message;
+
+  ret = 0;
+
+  do_normal_submit = 1;
+
+  CPS_NormalizeLine(line);
+
+  if (!*line) {
+    fflush(stderr);
+    fflush(stdout);
+    return 1;
+  };
+
+  command = line;
+  line = CPS_SplitWord(line);
+
+  if (!strcmp(command, "accheck")) {
+    do_normal_submit = process_cmd_accheck(&tx_message, line);
+  } else if (!strcmp(command, "activity")) {
+    do_normal_submit = 0;
+    ret = process_cmd_activity(line);
+  } else if (!strcmp(command, "add")) {
+    do_normal_submit = process_cmd_add_source(&tx_message, line);
+  } else if (!strcmp(command, "allow")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_ALLOW, REQ_ALLOWALL);
+  } else if (!strcmp(command, "authdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_authdata(line);
+  } else if (!strcmp(command, "burst")) {
+    do_normal_submit = process_cmd_burst(&tx_message, line);
+  } else if (!strcmp(command, "clients")) {
+    ret = process_cmd_clients(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "cmdaccheck")) {
+    do_normal_submit = process_cmd_cmdaccheck(&tx_message, line);
+  } else if (!strcmp(command, "cmdallow")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_CMDALLOW, REQ_CMDALLOWALL);
+  } else if (!strcmp(command, "cmddeny")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_CMDDENY, REQ_CMDDENYALL);
+  } else if (!strcmp(command, "cyclelogs")) {
+    process_cmd_cyclelogs(&tx_message, line);
+  } else if (!strcmp(command, "delete")) {
+    do_normal_submit = process_cmd_delete(&tx_message, line);
+  } else if (!strcmp(command, "deny")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_DENY, REQ_DENYALL);
+  } else if (!strcmp(command, "dfreq")) {
+    do_normal_submit = process_cmd_dfreq(&tx_message, line);
+  } else if (!strcmp(command, "dns")) {
+    ret = process_cmd_dns(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "doffset")) {
+    do_normal_submit = process_cmd_doffset(&tx_message, line);
+  } else if (!strcmp(command, "dump")) {
+    process_cmd_dump(&tx_message, line);
+  } else if (!strcmp(command, "exit")) {
+    do_normal_submit = 0;
+    quit = 1;
+    ret = 1;
+  } else if (!strcmp(command, "help")) {
+    do_normal_submit = 0;
+    give_help();
+    ret = 1;
+  } else if (!strcmp(command, "keygen")) {
+    ret = process_cmd_keygen(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "local")) {
+    do_normal_submit = process_cmd_local(&tx_message, line);
+  } else if (!strcmp(command, "makestep")) {
+    do_normal_submit = process_cmd_makestep(&tx_message, line);
+  } else if (!strcmp(command, "manual")) {
+    if (!strncmp(line, "list", 4)) {
+      do_normal_submit = 0;
+      ret = process_cmd_manual_list(CPS_SplitWord(line));
+    } else if (!strncmp(line, "delete", 6)) {
+      do_normal_submit = process_cmd_manual_delete(&tx_message, CPS_SplitWord(line));
+    } else {
+      do_normal_submit = process_cmd_manual(&tx_message, line);
+    }
+  } else if (!strcmp(command, "maxdelay")) {
+    do_normal_submit = process_cmd_maxdelay(&tx_message, line);
+  } else if (!strcmp(command, "maxdelaydevratio")) {
+    do_normal_submit = process_cmd_maxdelaydevratio(&tx_message, line);
+  } else if (!strcmp(command, "maxdelayratio")) {
+    do_normal_submit = process_cmd_maxdelayratio(&tx_message, line);
+  } else if (!strcmp(command, "maxpoll")) {
+    do_normal_submit = process_cmd_maxpoll(&tx_message, line);
+  } else if (!strcmp(command, "maxupdateskew")) {
+    do_normal_submit = process_cmd_maxupdateskew(&tx_message, line);
+  } else if (!strcmp(command, "minpoll")) {
+    do_normal_submit = process_cmd_minpoll(&tx_message, line);
+  } else if (!strcmp(command, "minstratum")) {
+    do_normal_submit = process_cmd_minstratum(&tx_message, line);
+  } else if (!strcmp(command, "ntpdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_ntpdata(line);
+  } else if (!strcmp(command, "offline")) {
+    do_normal_submit = process_cmd_offline(&tx_message, line);
+  } else if (!strcmp(command, "online")) {
+    do_normal_submit = process_cmd_online(&tx_message, line);
+  } else if (!strcmp(command, "onoffline")) {
+    process_cmd_onoffline(&tx_message, line);
+  } else if (!strcmp(command, "polltarget")) {
+    do_normal_submit = process_cmd_polltarget(&tx_message, line);
+  } else if (!strcmp(command, "quit")) {
+    do_normal_submit = 0;
+    quit = 1;
+    ret = 1;
+  } else if (!strcmp(command, "refresh")) {
+    process_cmd_refresh(&tx_message, line);
+  } else if (!strcmp(command, "rekey")) {
+    process_cmd_rekey(&tx_message, line);
+  } else if (!strcmp(command, "reload")) {
+    do_normal_submit = process_cmd_reload(&tx_message, line);
+  } else if (!strcmp(command, "reselect")) {
+    process_cmd_reselect(&tx_message, line);
+  } else if (!strcmp(command, "reselectdist")) {
+    do_normal_submit = process_cmd_reselectdist(&tx_message, line);
+  } else if (!strcmp(command, "reset")) {
+    do_normal_submit = process_cmd_reset(&tx_message, line);
+  } else if (!strcmp(command, "retries")) {
+    ret = process_cmd_retries(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "rtcdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_rtcreport(line);
+  } else if (!strcmp(command, "selectdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_selectdata(line);
+  } else if (!strcmp(command, "serverstats")) {
+    do_normal_submit = 0;
+    ret = process_cmd_serverstats(line);
+  } else if (!strcmp(command, "settime")) {
+    do_normal_submit = 0;
+    ret = process_cmd_settime(line);
+  } else if (!strcmp(command, "shutdown")) {
+    process_cmd_shutdown(&tx_message, line);
+  } else if (!strcmp(command, "smoothing")) {
+    do_normal_submit = 0;
+    ret = process_cmd_smoothing(line);
+  } else if (!strcmp(command, "smoothtime")) {
+    do_normal_submit = process_cmd_smoothtime(&tx_message, line);
+  } else if (!strcmp(command, "sourcename")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sourcename(line);
+  } else if (!strcmp(command, "sources")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sources(line);
+  } else if (!strcmp(command, "sourcestats")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sourcestats(line);
+  } else if (!strcmp(command, "timeout")) {
+    ret = process_cmd_timeout(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "tracking")) {
+    ret = process_cmd_tracking(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "trimrtc")) {
+    process_cmd_trimrtc(&tx_message, line);
+  } else if (!strcmp(command, "waitsync")) {
+    ret = process_cmd_waitsync(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "writertc")) {
+    process_cmd_writertc(&tx_message, line);
+  } else if (!strcmp(command, "authhash") ||
+             !strcmp(command, "password")) {
+    /* Warn, but don't return error to not break scripts */
+    LOG(LOGS_WARN, "Authentication is no longer supported");
+    do_normal_submit = 0;
+    ret = 1;
+  } else {
+    LOG(LOGS_ERR, "Unrecognized command");
+    do_normal_submit = 0;
+  }
+    
+  if (do_normal_submit) {
+    ret = request_reply(&tx_message, &rx_message, RPY_NULL, 1);
+  }
+
+  fflush(stderr);
+
+  if (fflush(stdout) != 0 || ferror(stdout) != 0) {
+    LOG(LOGS_ERR, "Could not write to stdout");
+
+    /* Return error for commands that print data */
+    if (!do_normal_submit)
+      return 0;
+  }
+
+  return ret;
+}
+
+/* ================================================== */
+
+#define MAX_LINE_LENGTH 2048
+
+static int
+process_args(int argc, char **argv, int multi)
+{
+  char line[MAX_LINE_LENGTH];
+  int i, l, ret = 0;
+
+  for (i = l = 0; i < argc; i++) {
+    l += snprintf(line + l, sizeof (line) - l, "%s ", argv[i]);
+    if (l >= sizeof (line)) {
+      LOG(LOGS_ERR, "Command too long");
+      return 0;
+    }
+
+    if (!multi && i + 1 < argc)
+      continue;
+
+    ret = process_line(line);
+    if (!ret || quit)
+      break;
+
+    l = 0;
+  }
+
+  return ret;
+}
+
+/* ================================================== */
+
+static void
+signal_handler(int signum)
+{
+  quit = 1;
+}
+
+/* ================================================== */
+
+static void
+display_gpl(void)
+{
+    printf("chrony version %s\n"
+           "Copyright (C) 1997-2003, 2007, 2009-2022 Richard P. Curnow and others\n"
+           "chrony comes with ABSOLUTELY NO WARRANTY.  This is free software, and\n"
+           "you are welcome to redistribute it under certain conditions.  See the\n"
+           "GNU General Public License version 2 for details.\n\n",
+           CHRONY_VERSION);
+}
+
+/* ================================================== */
+
+static void
+print_help(const char *progname)
+{
+      printf("Usage: %s [OPTION]... [COMMAND]...\n\n"
+             "Options:\n"
+             "  -4\t\tUse IPv4 addresses only\n"
+             "  -6\t\tUse IPv6 addresses only\n"
+             "  -n\t\tDon't resolve hostnames\n"
+             "  -N\t\tPrint original source names\n"
+             "  -c\t\tEnable CSV format\n"
+#if DEBUG > 0
+             "  -d\t\tEnable debug messages\n"
+#endif
+             "  -m\t\tAccept multiple commands\n"
+             "  -h HOST\tSpecify server (%s)\n"
+             "  -p PORT\tSpecify UDP port (%d)\n"
+             "  -v, --version\tPrint version and exit\n"
+             "      --help\tPrint usage and exit\n",
+             progname, DEFAULT_COMMAND_SOCKET",127.0.0.1,::1", DEFAULT_CANDM_PORT);
+}
+
+/* ================================================== */
+
+static void
+print_version(void)
+{
+      printf("chronyc (chrony) version %s (%s)\n", CHRONY_VERSION, CHRONYC_FEATURES);
+}
+
+/* ================================================== */
+
+int
+main(int argc, char **argv)
+{
+  char *line;
+  const char *progname = argv[0];
+  const char *hostnames = NULL;
+  int opt, ret = 1, multi = 0, family = IPADDR_UNSPEC;
+  int port = DEFAULT_CANDM_PORT;
+
+  /* Parse long command-line options */
+  for (optind = 1; optind < argc; optind++) {
+    if (!strcmp("--help", argv[optind])) {
+      print_help(progname);
+      return 0;
+    } else if (!strcmp("--version", argv[optind])) {
+      print_version();
+      return 0;
+    }
+  }
+
+  optind = 1;
+
+  /* Parse short command-line options */
+  while ((opt = getopt(argc, argv, "+46acdf:h:mnNp:v")) != -1) {
+    switch (opt) {
+      case '4':
+      case '6':
+        family = opt == '4' ? IPADDR_INET4 : IPADDR_INET6;
+        break;
+      case 'a':
+      case 'f':
+        /* For compatibility only */
+        break;
+      case 'c':
+        csv_mode = 1;
+        break;
+      case 'd':
+#if DEBUG > 0
+        log_min_severity = LOGS_DEBUG;
+#endif
+        break;
+      case 'h':
+        hostnames = optarg;
+        break;
+      case 'm':
+        multi = 1;
+        break;
+      case 'n':
+        no_dns = 1;
+        break;
+      case 'N':
+        source_names = 1;
+        break;
+      case 'p':
+        port = atoi(optarg);
+        break;
+      case 'v':
+        print_version();
+        return 0;
+      default:
+        print_help(progname);
+        return 1;
+    }
+  }
+
+  if (isatty(0) && isatty(1) && isatty(2)) {
+    on_terminal = 1;
+  }
+
+  if (on_terminal && optind == argc) {
+    display_gpl();
+  }
+  
+  DNS_SetAddressFamily(family);
+
+  if (!hostnames) {
+    hostnames = DEFAULT_COMMAND_SOCKET",127.0.0.1,::1";
+  }
+
+  UTI_SetQuitSignalsHandler(signal_handler, 0);
+
+  SCK_Initialise(IPADDR_UNSPEC);
+  server_addresses = get_addresses(hostnames, port);
+
+  if (!open_io())
+    LOG_FATAL("Could not open connection to daemon");
+
+  if (optind < argc) {
+    ret = process_args(argc - optind, argv + optind, multi);
+  } else {
+    do {
+      line = read_line();
+      if (line && !quit) {
+        ret = process_line(line);
+      }else {
+	/* supply the final '\n' when user exits via ^D */
+        if( on_terminal ) printf("\n");
+      }
+    } while (line && !quit);
+  }
+
+  close_io();
+  free_addresses(server_addresses);
+  SCK_Finalise();
+
+  return !ret;
+}
+
+
diff --git a/clientlog.c b/clientlog.c
new file mode 100644
index 0000000..adf0c59
--- /dev/null
+++ b/clientlog.c
@@ -0,0 +1,1088 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009, 2015-2017, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module keeps a count of the number of successful accesses by
+  clients, and the times of the last accesses.
+
+  This can be used for status reporting, and (in the case of a
+  server), if it needs to know which clients have made use of its data
+  recently.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "clientlog.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "ntp.h"
+#include "reports.h"
+#include "util.h"
+#include "logging.h"
+
+#define MAX_SERVICES 3
+
+typedef struct {
+  IPAddr ip_addr;
+  uint32_t last_hit[MAX_SERVICES];
+  uint32_t hits[MAX_SERVICES];
+  uint16_t drops[MAX_SERVICES];
+  uint16_t tokens[MAX_SERVICES];
+  int8_t rate[MAX_SERVICES];
+  int8_t ntp_timeout_rate;
+  uint8_t drop_flags;
+} Record;
+
+/* Hash table of records, there is a fixed number of records per slot */
+static ARR_Instance records;
+
+#define SLOT_BITS 4
+
+/* Number of records in one slot of the hash table */
+#define SLOT_SIZE (1U << SLOT_BITS)
+
+/* Minimum number of slots */
+#define MIN_SLOTS 1
+
+/* Maximum number of slots, this is a hard limit */
+#define MAX_SLOTS (1U << (24 - SLOT_BITS))
+
+/* Number of slots in the hash table */
+static unsigned int slots;
+
+/* Maximum number of slots given memory allocation limit */
+static unsigned int max_slots;
+
+/* Times of last hits are saved as 32-bit fixed point values */
+#define TS_FRAC 4
+#define INVALID_TS 0
+
+/* Static offset included in conversion to the fixed-point timestamps to
+   randomise their alignment */
+static uint32_t ts_offset;
+
+/* Request rates are saved in the record as 8-bit scaled log2 values */
+#define RATE_SCALE 4
+#define MIN_RATE (-14 * RATE_SCALE)
+#define INVALID_RATE -128
+
+/* Response rates are controlled by token buckets.  The capacity and
+   number of tokens spent on response are determined from configured
+   minimum inverval between responses (in log2) and burst length. */
+
+#define MIN_LIMIT_INTERVAL (-15 - TS_FRAC)
+#define MAX_LIMIT_INTERVAL 12
+#define MIN_LIMIT_BURST 1
+#define MAX_LIMIT_BURST 255
+
+static uint16_t max_tokens[MAX_SERVICES];
+static uint16_t tokens_per_hit[MAX_SERVICES];
+
+/* Reduction of token rates to avoid overflow of 16-bit counters.  Negative
+   shift is used for coarse limiting with intervals shorter than -TS_FRAC. */
+static int token_shift[MAX_SERVICES];
+
+/* Rates at which responses are randomly allowed (in log2) when the
+   buckets don't have enough tokens.  This is necessary in order to
+   prevent an attacker sending requests with spoofed source address
+   from blocking responses to the address completely. */
+
+#define MIN_LEAK_RATE 1
+#define MAX_LEAK_RATE 4
+
+static int leak_rate[MAX_SERVICES];
+
+/* Limit intervals in log2 */
+static int limit_interval[MAX_SERVICES];
+
+/* Flag indicating whether facility is turned on or not */
+static int active;
+
+/* RX and TX timestamp saved for clients using interleaved mode */
+typedef struct {
+  uint64_t rx_ts;
+  uint16_t flags;
+  uint16_t slew_epoch;
+  int32_t tx_ts_offset;
+} NtpTimestamps;
+
+/* Flags for NTP timestamps */
+#define NTPTS_DISABLED 1
+#define NTPTS_VALID_TX 2
+
+/* RX->TX map using a circular buffer with ordered timestamps */
+typedef struct {
+  ARR_Instance timestamps;
+  uint32_t first;
+  uint32_t size;
+  uint32_t max_size;
+  uint32_t cached_index;
+  uint64_t cached_rx_ts;
+  uint16_t slew_epoch;
+  double slew_offset;
+} NtpTimestampMap;
+
+static NtpTimestampMap ntp_ts_map;
+
+/* Maximum interval of NTP timestamps in future after a backward step */
+#define NTPTS_FUTURE_LIMIT (1LL << 32) /* 1 second */
+
+/* Maximum number of timestamps moved in the array to insert a new timestamp */
+#define NTPTS_INSERT_LIMIT 64
+
+/* Global statistics */
+static uint32_t total_hits[MAX_SERVICES];
+static uint32_t total_drops[MAX_SERVICES];
+static uint32_t total_ntp_auth_hits;
+static uint32_t total_ntp_interleaved_hits;
+static uint32_t total_record_drops;
+
+#define NSEC_PER_SEC 1000000000U
+
+/* ================================================== */
+
+static int expand_hashtable(void);
+static void handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+                        double doffset, LCL_ChangeType change_type, void *anything);
+
+/* ================================================== */
+
+static int
+compare_ts(uint32_t x, uint32_t y)
+{
+  if (x == y)
+    return 0;
+  if (y == INVALID_TS)
+    return 1;
+  return (int32_t)(x - y) > 0 ? 1 : -1;
+}
+
+/* ================================================== */
+
+static int
+compare_total_hits(Record *x, Record *y)
+{
+  uint32_t x_hits, y_hits;
+  int i;
+
+  for (i = 0, x_hits = y_hits = 0; i < MAX_SERVICES; i++) {
+    x_hits += x->hits[i];
+    y_hits += y->hits[i];
+  }
+
+  return x_hits > y_hits ? 1 : -1;
+}
+
+/* ================================================== */
+
+static Record *
+get_record(IPAddr *ip)
+{
+  uint32_t last_hit = 0, oldest_hit = 0;
+  Record *record, *oldest_record;
+  unsigned int first, i, j;
+
+  if (!active || (ip->family != IPADDR_INET4 && ip->family != IPADDR_INET6))
+    return NULL;
+
+  while (1) {
+    /* Get index of the first record in the slot */
+    first = UTI_IPToHash(ip) % slots * SLOT_SIZE;
+
+    for (i = 0, oldest_record = NULL; i < SLOT_SIZE; i++) {
+      record = ARR_GetElement(records, first + i);
+
+      if (!UTI_CompareIPs(ip, &record->ip_addr, NULL))
+        return record;
+
+      if (record->ip_addr.family == IPADDR_UNSPEC)
+        break;
+
+      for (j = 0; j < MAX_SERVICES; j++) {
+        if (j == 0 || compare_ts(last_hit, record->last_hit[j]) < 0)
+          last_hit = record->last_hit[j];
+      }
+
+      if (!oldest_record || compare_ts(oldest_hit, last_hit) > 0 ||
+          (oldest_hit == last_hit && compare_total_hits(oldest_record, record) > 0)) {
+        oldest_record = record;
+        oldest_hit = last_hit;
+      }
+    }
+
+    /* If the slot still has an empty record, use it */
+    if (record->ip_addr.family == IPADDR_UNSPEC)
+      break;
+
+    /* Resize the table if possible and try again as the new slot may
+       have some empty records */
+    if (expand_hashtable())
+      continue;
+
+    /* There is no other option, replace the oldest record */
+    record = oldest_record;
+    total_record_drops++;
+    break;
+  }
+
+  record->ip_addr = *ip;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->last_hit[i] = INVALID_TS;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->hits[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->drops[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->tokens[i] = max_tokens[i];
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->rate[i] = INVALID_RATE;
+  record->ntp_timeout_rate = INVALID_RATE;
+  record->drop_flags = 0;
+
+  return record;
+}
+
+/* ================================================== */
+
+static int
+expand_hashtable(void)
+{
+  ARR_Instance old_records;
+  Record *old_record, *new_record;
+  unsigned int i;
+
+  old_records = records;
+
+  if (2 * slots > max_slots)
+    return 0;
+
+  records = ARR_CreateInstance(sizeof (Record));
+
+  slots = MAX(MIN_SLOTS, 2 * slots);
+  assert(slots <= max_slots);
+
+  ARR_SetSize(records, slots * SLOT_SIZE);
+
+  /* Mark all new records as empty */
+  for (i = 0; i < slots * SLOT_SIZE; i++) {
+    new_record = ARR_GetElement(records, i);
+    new_record->ip_addr.family = IPADDR_UNSPEC;
+  }
+
+  if (!old_records)
+    return 1;
+
+  /* Copy old records to the new hash table */
+  for (i = 0; i < ARR_GetSize(old_records); i++) {
+    old_record = ARR_GetElement(old_records, i);
+    if (old_record->ip_addr.family == IPADDR_UNSPEC)
+      continue;
+
+    new_record = get_record(&old_record->ip_addr);
+
+    assert(new_record);
+    *new_record = *old_record;
+  }
+
+  ARR_DestroyInstance(old_records);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_bucket_params(int interval, int burst, uint16_t *max_tokens,
+                  uint16_t *tokens_per_packet, int *token_shift)
+{
+  interval = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
+  burst = CLAMP(MIN_LIMIT_BURST, burst, MAX_LIMIT_BURST);
+
+  if (interval >= -TS_FRAC) {
+    /* Find the smallest shift with which the maximum number fits in 16 bits */
+    for (*token_shift = 0; *token_shift < interval + TS_FRAC; (*token_shift)++) {
+      if (burst << (TS_FRAC + interval - *token_shift) < 1U << 16)
+        break;
+    }
+  } else {
+    /* Coarse rate limiting */
+    *token_shift = interval + TS_FRAC;
+    *tokens_per_packet = 1;
+    burst = MAX(1U << -*token_shift, burst);
+  }
+
+  *tokens_per_packet = 1U << (TS_FRAC + interval - *token_shift);
+  *max_tokens = *tokens_per_packet * burst;
+
+  DEBUG_LOG("Tokens max %d packet %d shift %d",
+            *max_tokens, *tokens_per_packet, *token_shift);
+}
+
+/* ================================================== */
+
+void
+CLG_Initialise(void)
+{
+  int i, interval, burst, lrate, slots2;
+
+  for (i = 0; i < MAX_SERVICES; i++) {
+    max_tokens[i] = 0;
+    tokens_per_hit[i] = 0;
+    token_shift[i] = 0;
+    leak_rate[i] = 0;
+    limit_interval[i] = MIN_LIMIT_INTERVAL;
+
+    switch (i) {
+      case CLG_NTP:
+        if (!CNF_GetNTPRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_NTSKE:
+        if (!CNF_GetNtsRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_CMDMON:
+        if (!CNF_GetCommandRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      default:
+        assert(0);
+    }
+
+    set_bucket_params(interval, burst, &max_tokens[i], &tokens_per_hit[i], &token_shift[i]);
+    leak_rate[i] = CLAMP(MIN_LEAK_RATE, lrate, MAX_LEAK_RATE);
+    limit_interval[i] = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
+  }
+
+  active = !CNF_GetNoClientLog();
+  if (!active) {
+    for (i = 0; i < MAX_SERVICES; i++) {
+      if (leak_rate[i] != 0)
+        LOG_FATAL("Rate limiting cannot be enabled with noclientlog");
+    }
+    return;
+  }
+
+  /* Calculate the maximum number of slots that can be allocated in the
+     configured memory limit.  Take into account expanding of the hash
+     table where two copies exist at the same time. */
+  max_slots = CNF_GetClientLogLimit() /
+              ((sizeof (Record) + sizeof (NtpTimestamps)) * SLOT_SIZE * 3 / 2);
+  max_slots = CLAMP(MIN_SLOTS, max_slots, MAX_SLOTS);
+  for (slots2 = 0; 1U << (slots2 + 1) <= max_slots; slots2++)
+    ;
+
+  DEBUG_LOG("Max records %u", 1U << (slots2 + SLOT_BITS));
+
+  slots = 0;
+  records = NULL;
+
+  expand_hashtable();
+
+  UTI_GetRandomBytes(&ts_offset, sizeof (ts_offset));
+  ts_offset %= NSEC_PER_SEC / (1U << TS_FRAC);
+
+  ntp_ts_map.timestamps = NULL;
+  ntp_ts_map.first = 0;
+  ntp_ts_map.size = 0;
+  ntp_ts_map.max_size = 1U << (slots2 + SLOT_BITS);
+  ntp_ts_map.cached_index = 0;
+  ntp_ts_map.cached_rx_ts = 0ULL;
+  ntp_ts_map.slew_epoch = 0;
+  ntp_ts_map.slew_offset = 0.0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+}
+
+/* ================================================== */
+
+void
+CLG_Finalise(void)
+{
+  if (!active)
+    return;
+
+  ARR_DestroyInstance(records);
+  if (ntp_ts_map.timestamps)
+    ARR_DestroyInstance(ntp_ts_map.timestamps);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+}
+
+/* ================================================== */
+
+static uint32_t
+get_ts_from_timespec(struct timespec *ts)
+{
+  uint32_t sec = ts->tv_sec, nsec = ts->tv_nsec;
+
+  nsec += ts_offset;
+  if (nsec >= NSEC_PER_SEC) {
+    nsec -= NSEC_PER_SEC;
+    sec++;
+  }
+
+  /* This is fast and accurate enough */
+  return sec << TS_FRAC | (140740U * (nsec >> 15)) >> (32 - TS_FRAC);
+}
+
+/* ================================================== */
+
+static void
+update_record(CLG_Service service, Record *record, struct timespec *now)
+{
+  uint32_t interval, now_ts, prev_hit, tokens;
+  int interval2, tshift, mtokens;
+  int8_t *rate;
+
+  now_ts = get_ts_from_timespec(now);
+
+  prev_hit = record->last_hit[service];
+  record->last_hit[service] = now_ts;
+  record->hits[service]++;
+
+  interval = now_ts - prev_hit;
+
+  if (prev_hit == INVALID_TS || (int32_t)interval < 0)
+    return;
+
+  tshift = token_shift[service];
+  mtokens = max_tokens[service];
+
+  if (tshift >= 0)
+    tokens = (now_ts >> tshift) - (prev_hit >> tshift);
+  else if (now_ts - prev_hit > mtokens)
+    tokens = mtokens;
+  else
+    tokens = (now_ts - prev_hit) << -tshift;
+  record->tokens[service] = MIN(record->tokens[service] + tokens, mtokens);
+
+  /* Convert the interval to scaled and rounded log2 */
+  if (interval) {
+    interval += interval >> 1;
+    for (interval2 = -RATE_SCALE * TS_FRAC; interval2 < -MIN_RATE;
+         interval2 += RATE_SCALE) {
+      if (interval <= 1)
+        break;
+      interval >>= 1;
+    }
+  } else {
+    interval2 = -RATE_SCALE * (TS_FRAC + 1);
+  }
+
+  /* For the NTP service, update one of the two rates depending on whether
+     the previous request of the client had a reply or it timed out */
+  rate = service == CLG_NTP && record->drop_flags & (1U << service) ?
+           &record->ntp_timeout_rate : &record->rate[service];
+
+  /* Update the rate in a rough approximation of exponential moving average */
+  if (*rate == INVALID_RATE) {
+    *rate = -interval2;
+  } else {
+    if (*rate < -interval2) {
+      (*rate)++;
+    } else if (*rate > -interval2) {
+      if (*rate > RATE_SCALE * 5 / 2 - interval2)
+        *rate = RATE_SCALE * 5 / 2 - interval2;
+      else
+        *rate = (*rate - interval2 - 1) / 2;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+get_index(Record *record)
+{
+  return record - (Record *)ARR_GetElements(records);
+}
+
+/* ================================================== */
+
+int
+CLG_GetClientIndex(IPAddr *client)
+{
+  Record *record;
+
+  record = get_record(client);
+  if (record == NULL)
+    return -1;
+
+  return get_index(record);
+}
+
+/* ================================================== */
+
+static void
+check_service_number(CLG_Service service)
+{
+  assert(service >= 0 && service <= MAX_SERVICES);
+}
+
+/* ================================================== */
+
+int
+CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now)
+{
+  Record *record;
+
+  check_service_number(service);
+
+  total_hits[service]++;
+
+  record = get_record(client);
+  if (record == NULL)
+    return -1;
+
+  update_record(service, record, now);
+
+  DEBUG_LOG("service %d hits %"PRIu32" rate %d trate %d tokens %d",
+            (int)service, record->hits[service], record->rate[service],
+            service == CLG_NTP ? record->ntp_timeout_rate : INVALID_RATE,
+            record->tokens[service]);
+
+  return get_index(record);
+}
+
+/* ================================================== */
+
+static int
+limit_response_random(int leak_rate)
+{
+  static uint32_t rnd;
+  static int bits_left = 0;
+  int r;
+
+  if (bits_left < leak_rate) {
+    UTI_GetRandomBytes(&rnd, sizeof (rnd));
+    bits_left = 8 * sizeof (rnd);
+  }
+
+  /* Return zero on average once per 2^leak_rate */
+  r = rnd % (1U << leak_rate) ? 1 : 0;
+  rnd >>= leak_rate;
+  bits_left -= leak_rate;
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+CLG_LimitServiceRate(CLG_Service service, int index)
+{
+  Record *record;
+  int drop;
+
+  check_service_number(service);
+
+  if (tokens_per_hit[service] == 0)
+    return 0;
+
+  record = ARR_GetElement(records, index);
+  record->drop_flags &= ~(1U << service);
+
+  if (record->tokens[service] >= tokens_per_hit[service]) {
+    record->tokens[service] -= tokens_per_hit[service];
+    return 0;
+  }
+
+  drop = limit_response_random(leak_rate[service]);
+
+  /* Poorly implemented NTP clients can send requests at a higher rate
+     when they are not getting replies.  If the request rate seems to be more
+     than twice as much as when replies are sent, give up on rate limiting to
+     reduce the amount of traffic.  Invert the sense of the leak to respond to
+     most of the requests, but still keep the estimated rate updated. */
+  if (service == CLG_NTP && record->ntp_timeout_rate != INVALID_RATE &&
+      record->ntp_timeout_rate > record->rate[service] + RATE_SCALE)
+    drop = !drop;
+
+  if (!drop) {
+    record->tokens[service] = 0;
+    return 0;
+  }
+
+  record->drop_flags |= 1U << service;
+  record->drops[service]++;
+  total_drops[service]++;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CLG_LogAuthNtpRequest(void)
+{
+  total_ntp_auth_hits++;
+}
+
+/* ================================================== */
+
+int
+CLG_GetNtpMinPoll(void)
+{
+  return limit_interval[CLG_NTP];
+}
+
+/* ================================================== */
+
+static NtpTimestamps *
+get_ntp_tss(uint32_t index)
+{
+  return ARR_GetElement(ntp_ts_map.timestamps,
+                        (ntp_ts_map.first + index) & (ntp_ts_map.max_size - 1));
+}
+
+/* ================================================== */
+
+static int
+find_ntp_rx_ts(uint64_t rx_ts, uint32_t *index)
+{
+  uint64_t rx_x, rx_lo, rx_hi, step;
+  uint32_t i, x, lo, hi;
+
+  if (ntp_ts_map.cached_rx_ts == rx_ts && rx_ts != 0ULL) {
+    *index = ntp_ts_map.cached_index;
+    return 1;
+  }
+
+  if (ntp_ts_map.size == 0) {
+    *index = 0;
+    return 0;
+  }
+
+  lo = 0;
+  hi = ntp_ts_map.size - 1;
+  rx_lo = get_ntp_tss(lo)->rx_ts;
+  rx_hi = get_ntp_tss(hi)->rx_ts;
+
+  /* Check for ts < lo before ts > hi to trim timestamps from "future" later
+     if both conditions are true to not break the order of the endpoints.
+     Compare timestamps by their difference to allow adjacent NTP eras. */
+  if ((int64_t)(rx_ts - rx_lo) < 0) {
+    *index = 0;
+    return 0;
+  } else if ((int64_t)(rx_ts - rx_hi) > 0) {
+    *index = ntp_ts_map.size;
+    return 0;
+  }
+
+  /* Perform a combined linear interpolation and binary search */
+
+  for (i = 0; ; i++) {
+    if (rx_ts == rx_hi) {
+      *index = ntp_ts_map.cached_index = hi;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (rx_ts == rx_lo) {
+      *index = ntp_ts_map.cached_index = lo;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (lo + 1 == hi) {
+      *index = hi;
+      return 0;
+    }
+
+    if (hi - lo > 3 && i % 2 == 0) {
+      step = (rx_hi - rx_lo) / (hi - lo);
+      if (step == 0)
+        step = 1;
+      x = lo + (rx_ts - rx_lo) / step;
+    } else {
+      x = lo + (hi - lo) / 2;
+    }
+
+    if (x <= lo)
+      x = lo + 1;
+    else if (x >= hi)
+      x = hi - 1;
+
+    rx_x = get_ntp_tss(x)->rx_ts;
+
+    if ((int64_t)(rx_x - rx_ts) <= 0) {
+      lo = x;
+      rx_lo = rx_x;
+    } else {
+      hi = x;
+      rx_hi = rx_x;
+    }
+  }
+}
+
+/* ================================================== */
+
+static uint64_t
+ntp64_to_int64(NTP_int64 *ts)
+{
+  return (uint64_t)ntohl(ts->hi) << 32 | ntohl(ts->lo);
+}
+
+/* ================================================== */
+
+static void
+int64_to_ntp64(uint64_t ts, NTP_int64 *ntp_ts)
+{
+  ntp_ts->hi = htonl(ts >> 32);
+  ntp_ts->lo = htonl(ts);
+}
+
+/* ================================================== */
+
+static uint32_t
+push_ntp_tss(uint32_t index)
+{
+  if (ntp_ts_map.size < ntp_ts_map.max_size) {
+    ntp_ts_map.size++;
+  } else {
+    ntp_ts_map.first = (ntp_ts_map.first + 1) % (ntp_ts_map.max_size);
+    if (index > 0)
+      index--;
+  }
+
+  return index;
+}
+
+/* ================================================== */
+
+static void
+set_ntp_tx_offset(NtpTimestamps *tss, NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  struct timespec ts;
+
+  if (!tx_ts) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  UTI_Ntp64ToTimespec(rx_ts, &ts);
+  UTI_DiffTimespecs(&ts, tx_ts, &ts);
+
+  if (ts.tv_sec < -2 || ts.tv_sec > 1) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  tss->tx_ts_offset = (int32_t)ts.tv_nsec + (int32_t)ts.tv_sec * (int32_t)NSEC_PER_SEC;
+  tss->flags |= NTPTS_VALID_TX;
+}
+
+/* ================================================== */
+
+static void
+get_ntp_tx(NtpTimestamps *tss, struct timespec *tx_ts)
+{
+  int32_t offset = tss->tx_ts_offset;
+  NTP_int64 ntp_ts;
+
+  if (tss->flags & NTPTS_VALID_TX) {
+    int64_to_ntp64(tss->rx_ts, &ntp_ts);
+    UTI_Ntp64ToTimespec(&ntp_ts, tx_ts);
+    if (offset >= (int32_t)NSEC_PER_SEC) {
+      offset -= NSEC_PER_SEC;
+      tx_ts->tv_sec++;
+    }
+    tx_ts->tv_nsec += offset;
+    UTI_NormaliseTimespec(tx_ts);
+  } else {
+    UTI_ZeroTimespec(tx_ts);
+  }
+}
+
+/* ================================================== */
+
+void
+CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  NtpTimestamps *tss;
+  uint32_t i, index;
+  uint64_t rx;
+
+  if (!active)
+    return;
+
+  /* Allocate the array on first use */
+  if (!ntp_ts_map.timestamps) {
+    ntp_ts_map.timestamps = ARR_CreateInstance(sizeof (NtpTimestamps));
+    ARR_SetSize(ntp_ts_map.timestamps, ntp_ts_map.max_size);
+  }
+
+  rx = ntp64_to_int64(rx_ts);
+
+  if (rx == 0ULL)
+    return;
+
+  /* Disable the RX timestamp if it already exists to avoid responding
+     with a wrong TX timestamp */
+  if (find_ntp_rx_ts(rx, &index)) {
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+    return;
+  }
+
+  assert(index <= ntp_ts_map.size);
+
+  if (index == ntp_ts_map.size) {
+    /* Increase the size or drop the oldest timestamp to make room for
+       the new timestamp */
+    index = push_ntp_tss(index);
+  } else {
+    /* Trim timestamps in distant future after backward step */
+    while (index < ntp_ts_map.size &&
+           get_ntp_tss(ntp_ts_map.size - 1)->rx_ts - rx > NTPTS_FUTURE_LIMIT)
+      ntp_ts_map.size--;
+
+    /* Insert the timestamp if it is close to the latest timestamp.
+       Otherwise, replace the closest older or the oldest timestamp. */
+    if (index + NTPTS_INSERT_LIMIT >= ntp_ts_map.size) {
+      index = push_ntp_tss(index);
+      for (i = ntp_ts_map.size - 1; i > index; i--)
+        *get_ntp_tss(i) = *get_ntp_tss(i - 1);
+    } else {
+      if (index > 0)
+        index--;
+    }
+  }
+
+  ntp_ts_map.cached_index = index;
+  ntp_ts_map.cached_rx_ts = rx;
+
+  tss = get_ntp_tss(index);
+  tss->rx_ts = rx;
+  tss->flags = 0;
+  tss->slew_epoch = ntp_ts_map.slew_epoch;
+  set_ntp_tx_offset(tss, rx_ts, tx_ts);
+
+  DEBUG_LOG("Saved RX+TX index=%"PRIu32" first=%"PRIu32" size=%"PRIu32,
+            index, ntp_ts_map.first, ntp_ts_map.size);
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  /* Drop all timestamps on unknown step */
+  if (change_type == LCL_ChangeUnknownStep) {
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+  }
+
+  ntp_ts_map.slew_epoch++;
+  ntp_ts_map.slew_offset = doffset;
+}
+
+/* ================================================== */
+
+void
+CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  /* If the RX timestamp was captured before the last correction of the clock,
+     remove the adjustment from the TX timestamp */
+  if ((uint16_t)(get_ntp_tss(index)->slew_epoch + 1U) == ntp_ts_map.slew_epoch)
+    UTI_AddDoubleToTimespec(tx_ts, ntp_ts_map.slew_offset, tx_ts);
+}
+
+/* ================================================== */
+
+void
+CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  set_ntp_tx_offset(get_ntp_tss(index), rx_ts, tx_ts);
+}
+
+/* ================================================== */
+
+int
+CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  NtpTimestamps *tss;
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return 0;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return 0;
+
+  tss = get_ntp_tss(index);
+
+  if (tss->flags & NTPTS_DISABLED)
+    return 0;
+
+  get_ntp_tx(tss, tx_ts);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CLG_DisableNtpTimestamps(NTP_int64 *rx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+
+  /* This assumes the function is called only to prevent multiple
+     interleaved responses to the same timestamp */
+  total_ntp_interleaved_hits++;
+}
+
+/* ================================================== */
+
+int
+CLG_GetNumberOfIndices(void)
+{
+  if (!active)
+    return -1;
+
+  return ARR_GetSize(records);
+}
+
+/* ================================================== */
+
+static int get_interval(int rate)
+{
+  if (rate == INVALID_RATE)
+    return 127;
+
+  rate += rate > 0 ? RATE_SCALE / 2 : -RATE_SCALE / 2;
+
+  return rate / -RATE_SCALE;
+}
+
+/* ================================================== */
+
+static uint32_t get_last_ago(uint32_t x, uint32_t y)
+{
+  if (y == INVALID_TS || (int32_t)(x - y) < 0)
+    return -1;
+
+  return (x - y) >> TS_FRAC;
+}
+
+/* ================================================== */
+
+int
+CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                 RPT_ClientAccessByIndex_Report *report, struct timespec *now)
+{
+  Record *record;
+  uint32_t now_ts;
+  int i, r;
+
+  if (!active || index < 0 || index >= ARR_GetSize(records))
+    return 0;
+
+  record = ARR_GetElement(records, index);
+
+  if (record->ip_addr.family == IPADDR_UNSPEC)
+    return 0;
+
+  if (min_hits == 0) {
+    r = 1;
+  } else {
+    for (i = r = 0; i < MAX_SERVICES; i++) {
+      if (record->hits[i] >= min_hits) {
+        r = 1;
+        break;
+      }
+    }
+  }
+
+  if (r) {
+    now_ts = get_ts_from_timespec(now);
+
+    report->ip_addr = record->ip_addr;
+    report->ntp_hits = record->hits[CLG_NTP];
+    report->nke_hits = record->hits[CLG_NTSKE];
+    report->cmd_hits = record->hits[CLG_CMDMON];
+    report->ntp_drops = record->drops[CLG_NTP];
+    report->nke_drops = record->drops[CLG_NTSKE];
+    report->cmd_drops = record->drops[CLG_CMDMON];
+    report->ntp_interval = get_interval(record->rate[CLG_NTP]);
+    report->nke_interval = get_interval(record->rate[CLG_NTSKE]);
+    report->cmd_interval = get_interval(record->rate[CLG_CMDMON]);
+    report->ntp_timeout_interval = get_interval(record->ntp_timeout_rate);
+    report->last_ntp_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTP]);
+    report->last_nke_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTSKE]);
+    report->last_cmd_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_CMDMON]);
+  }
+
+  if (reset) {
+    for (i = 0; i < MAX_SERVICES; i++) {
+      record->hits[i] = 0;
+      record->drops[i] = 0;
+    }
+  }
+
+  return r;
+}
+
+/* ================================================== */
+
+void
+CLG_GetServerStatsReport(RPT_ServerStatsReport *report)
+{
+  report->ntp_hits = total_hits[CLG_NTP];
+  report->nke_hits = total_hits[CLG_NTSKE];
+  report->cmd_hits = total_hits[CLG_CMDMON];
+  report->ntp_drops = total_drops[CLG_NTP];
+  report->nke_drops = total_drops[CLG_NTSKE];
+  report->cmd_drops = total_drops[CLG_CMDMON];
+  report->log_drops = total_record_drops;
+  report->ntp_auth_hits = total_ntp_auth_hits;
+  report->ntp_interleaved_hits = total_ntp_interleaved_hits;
+  report->ntp_timestamps = ntp_ts_map.size;
+  report->ntp_span_seconds = ntp_ts_map.size > 1 ?
+                             (get_ntp_tss(ntp_ts_map.size - 1)->rx_ts -
+                              get_ntp_tss(0)->rx_ts) >> 32 : 0;
+}
diff --git a/clientlog.h b/clientlog.h
new file mode 100644
index 0000000..2a5565e
--- /dev/null
+++ b/clientlog.h
@@ -0,0 +1,63 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module contains facilities for logging access by clients.
+
+  */
+
+#ifndef GOT_CLIENTLOG_H
+#define GOT_CLIENTLOG_H
+
+#include "sysincl.h"
+#include "reports.h"
+
+typedef enum {
+  CLG_NTP = 0,
+  CLG_NTSKE,
+  CLG_CMDMON,
+} CLG_Service;
+
+extern void CLG_Initialise(void);
+extern void CLG_Finalise(void);
+extern int CLG_GetClientIndex(IPAddr *client);
+extern int CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now);
+extern int CLG_LimitServiceRate(CLG_Service service, int index);
+extern void CLG_LogAuthNtpRequest(void);
+extern int CLG_GetNtpMinPoll(void);
+
+/* Functions to save and retrieve timestamps for server interleaved mode */
+extern void CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern int CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_DisableNtpTimestamps(NTP_int64 *rx_ts);
+
+/* And some reporting functions, for use by chronyc. */
+
+extern int CLG_GetNumberOfIndices(void);
+extern int CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                            RPT_ClientAccessByIndex_Report *report,
+                                            struct timespec *now);
+extern void CLG_GetServerStatsReport(RPT_ServerStatsReport *report);
+
+#endif /* GOT_CLIENTLOG_H */
diff --git a/cmac.h b/cmac.h
new file mode 100644
index 0000000..935820d
--- /dev/null
+++ b/cmac.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for CMAC.
+
+  */
+
+#ifndef GOT_CMAC_H
+#define GOT_CMAC_H
+
+/* Avoid overlapping with the hash enumeration */
+typedef enum {
+  CMC_INVALID = 0,
+  CMC_AES128 = 13,
+  CMC_AES256 = 14,
+} CMC_Algorithm;
+
+typedef struct CMC_Instance_Record *CMC_Instance;
+
+extern int CMC_GetKeyLength(CMC_Algorithm algorithm);
+extern CMC_Instance CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key,
+                                       int length);
+extern int CMC_Hash(CMC_Instance inst, const void *in, int in_len,
+                    unsigned char *out, int out_len);
+extern void CMC_DestroyInstance(CMC_Instance inst);
+
+#endif
+
diff --git a/cmac_gnutls.c b/cmac_gnutls.c
new file mode 100644
index 0000000..d1cd550
--- /dev/null
+++ b/cmac_gnutls.c
@@ -0,0 +1,189 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  CMAC using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "cmac.h"
+#include "hash.h"
+#include "logging.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+  gnutls_mac_algorithm_t algorithm;
+  gnutls_hmac_hd_t mac;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  DEBUG_LOG("Initialised");
+  gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  assert(gnutls_initialised);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_mac_algorithm_t
+get_mac_algorithm(CMC_Algorithm algorithm)
+{
+  switch (algorithm) {
+    case CMC_AES128:
+      return GNUTLS_MAC_AES_CMAC_128;
+    case CMC_AES256:
+      return GNUTLS_MAC_AES_CMAC_256;
+    default:
+      return GNUTLS_MAC_UNKNOWN;
+  }
+}
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  gnutls_mac_algorithm_t malgo = get_mac_algorithm(algorithm);
+  int len;
+
+  if (malgo == GNUTLS_MAC_UNKNOWN)
+    return 0;
+
+  len = gnutls_hmac_get_key_size(malgo);
+
+  if (len < 0)
+    return 0;
+
+  return len;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  gnutls_hmac_hd_t handle;
+  CMC_Instance inst;
+
+  int r;
+
+  if (instance_counter == 0)
+    init_gnutls();
+
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+    goto error;
+
+  r = gnutls_hmac_init(&handle, get_mac_algorithm(algorithm), key, length);
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "mac", gnutls_strerror(r));
+    goto error;
+  }
+
+  inst = MallocNew(struct CMC_Instance_Record);
+  inst->algorithm = get_mac_algorithm(algorithm);
+  inst->mac = handle;
+
+  instance_counter++;
+
+  return inst;
+
+error:
+  if (instance_counter == 0)
+    deinit_gnutls();
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  int hash_len;
+
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
+  hash_len = gnutls_hmac_get_len(inst->algorithm);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hmac(inst->mac, in, in_len) < 0) {
+    /* Reset the state */
+    gnutls_hmac_output(inst->mac, buf);
+    return 0;
+  }
+
+  gnutls_hmac_output(inst->mac, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+  gnutls_hmac_deinit(inst->mac, NULL);
+  Free(inst);
+
+  instance_counter--;
+  if (instance_counter == 0)
+    deinit_gnutls();
+}
diff --git a/cmac_nettle.c b/cmac_nettle.c
new file mode 100644
index 0000000..5b2c0d4
--- /dev/null
+++ b/cmac_nettle.c
@@ -0,0 +1,117 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Support for AES128 and AES256 CMAC in Nettle.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <nettle/cmac.h>
+
+#include "cmac.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+  int key_length;
+  union {
+    struct cmac_aes128_ctx aes128;
+    struct cmac_aes256_ctx aes256;
+  } context;
+};
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  if (algorithm == CMC_AES128)
+    return AES128_KEY_SIZE;
+  else if (algorithm == CMC_AES256)
+    return AES256_KEY_SIZE;
+  return 0;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  CMC_Instance inst;
+
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+    return NULL;
+
+  inst = MallocNew(struct CMC_Instance_Record);
+  inst->key_length = length;
+
+  switch (length) {
+    case AES128_KEY_SIZE:
+      cmac_aes128_set_key(&inst->context.aes128, key);
+      break;
+    case AES256_KEY_SIZE:
+      cmac_aes256_set_key(&inst->context.aes256, key);
+      break;
+    default:
+      assert(0);
+  }
+
+  return inst;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
+  if (out_len > CMAC128_DIGEST_SIZE)
+    out_len = CMAC128_DIGEST_SIZE;
+
+  switch (inst->key_length) {
+    case AES128_KEY_SIZE:
+      cmac_aes128_update(&inst->context.aes128, in_len, in);
+      cmac_aes128_digest(&inst->context.aes128, out_len, out);
+      break;
+    case AES256_KEY_SIZE:
+      cmac_aes256_update(&inst->context.aes256, in_len, in);
+      cmac_aes256_digest(&inst->context.aes256, out_len, out);
+      break;
+    default:
+      assert(0);
+  }
+
+  return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+  Free(inst);
+}
diff --git a/cmdmon.c b/cmdmon.c
new file mode 100644
index 0000000..e48a2fc
--- /dev/null
+++ b/cmdmon.c
@@ -0,0 +1,1814 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2016, 2018-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Command and monitoring module in the main program
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "cmdmon.h"
+#include "candm.h"
+#include "sched.h"
+#include "util.h"
+#include "logging.h"
+#include "keys.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "smooth.h"
+#include "socket.h"
+#include "sources.h"
+#include "sourcestats.h"
+#include "reference.h"
+#include "manual.h"
+#include "memory.h"
+#include "nts_ke_server.h"
+#include "local.h"
+#include "addrfilt.h"
+#include "conf.h"
+#include "rtc.h"
+#include "pktlength.h"
+#include "clientlog.h"
+#include "refclock.h"
+
+/* ================================================== */
+
+#define INVALID_SOCK_FD (-5)
+
+/* File descriptors for command and monitoring sockets */
+static int sock_fdu;
+static int sock_fd4;
+static int sock_fd6;
+
+/* Flag indicating the IPv4 socket is bound to an address */
+static int bound_sock_fd4;
+
+/* Flag indicating whether this module has been initialised or not */
+static int initialised = 0;
+
+/* ================================================== */
+/* Array of permission levels for command types */
+
+static const char permissions[] = {
+  PERMIT_OPEN, /* NULL */
+  PERMIT_AUTH, /* ONLINE */
+  PERMIT_AUTH, /* OFFLINE */
+  PERMIT_AUTH, /* BURST */
+  PERMIT_AUTH, /* MODIFY_MINPOLL */
+  PERMIT_AUTH, /* MODIFY_MAXPOLL */
+  PERMIT_AUTH, /* DUMP */
+  PERMIT_AUTH, /* MODIFY_MAXDELAY */
+  PERMIT_AUTH, /* MODIFY_MAXDELAYRATIO */
+  PERMIT_AUTH, /* MODIFY_MAXUPDATESKEW */
+  PERMIT_OPEN, /* LOGON */
+  PERMIT_AUTH, /* SETTIME */
+  PERMIT_AUTH, /* LOCAL */
+  PERMIT_AUTH, /* MANUAL */
+  PERMIT_OPEN, /* N_SOURCES */
+  PERMIT_OPEN, /* SOURCE_DATA */
+  PERMIT_AUTH, /* REKEY */
+  PERMIT_AUTH, /* ALLOW */
+  PERMIT_AUTH, /* ALLOWALL */
+  PERMIT_AUTH, /* DENY */
+  PERMIT_AUTH, /* DENYALL */
+  PERMIT_AUTH, /* CMDALLOW */
+  PERMIT_AUTH, /* CMDALLOWALL */
+  PERMIT_AUTH, /* CMDDENY */
+  PERMIT_AUTH, /* CMDDENYALL */
+  PERMIT_AUTH, /* ACCHECK */
+  PERMIT_AUTH, /* CMDACCHECK */
+  PERMIT_AUTH, /* ADD_SERVER */
+  PERMIT_AUTH, /* ADD_PEER */
+  PERMIT_AUTH, /* DEL_SOURCE */
+  PERMIT_AUTH, /* WRITERTC */
+  PERMIT_AUTH, /* DFREQ */
+  PERMIT_AUTH, /* DOFFSET */
+  PERMIT_OPEN, /* TRACKING */
+  PERMIT_OPEN, /* SOURCESTATS */
+  PERMIT_OPEN, /* RTCREPORT */
+  PERMIT_AUTH, /* TRIMRTC */
+  PERMIT_AUTH, /* CYCLELOGS */
+  PERMIT_AUTH, /* SUBNETS_ACCESSED */
+  PERMIT_AUTH, /* CLIENT_ACCESSES (by subnet) */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX */
+  PERMIT_OPEN, /* MANUAL_LIST */
+  PERMIT_AUTH, /* MANUAL_DELETE */
+  PERMIT_AUTH, /* MAKESTEP */
+  PERMIT_OPEN, /* ACTIVITY */
+  PERMIT_AUTH, /* MODIFY_MINSTRATUM */
+  PERMIT_AUTH, /* MODIFY_POLLTARGET */
+  PERMIT_AUTH, /* MODIFY_MAXDELAYDEVRATIO */
+  PERMIT_AUTH, /* RESELECT */
+  PERMIT_AUTH, /* RESELECTDISTANCE */
+  PERMIT_AUTH, /* MODIFY_MAKESTEP */
+  PERMIT_OPEN, /* SMOOTHING */
+  PERMIT_AUTH, /* SMOOTHTIME */
+  PERMIT_AUTH, /* REFRESH */
+  PERMIT_AUTH, /* SERVER_STATS */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX2 */
+  PERMIT_AUTH, /* LOCAL2 */
+  PERMIT_AUTH, /* NTP_DATA */
+  PERMIT_AUTH, /* ADD_SERVER2 */
+  PERMIT_AUTH, /* ADD_PEER2 */
+  PERMIT_AUTH, /* ADD_SERVER3 */
+  PERMIT_AUTH, /* ADD_PEER3 */
+  PERMIT_AUTH, /* SHUTDOWN */
+  PERMIT_AUTH, /* ONOFFLINE */
+  PERMIT_AUTH, /* ADD_SOURCE */
+  PERMIT_OPEN, /* NTP_SOURCE_NAME */
+  PERMIT_AUTH, /* RESET_SOURCES */
+  PERMIT_AUTH, /* AUTH_DATA */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX3 */
+  PERMIT_AUTH, /* SELECT_DATA */
+  PERMIT_AUTH, /* RELOAD_SOURCES */
+  PERMIT_AUTH, /* DOFFSET2 */
+};
+
+/* ================================================== */
+
+/* This authorisation table is used for checking whether particular
+   machines are allowed to make command and monitoring requests. */
+static ADF_AuthTable access_auth_table;
+
+/* ================================================== */
+/* Forward prototypes */
+static void read_from_cmd_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static int
+open_socket(int family)
+{
+  const char *local_path, *iface;
+  IPSockAddr local_addr;
+  int sock_fd, port;
+
+  switch (family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+      port = CNF_GetCommandPort();
+      if (port == 0 || !SCK_IsIpFamilyEnabled(family))
+        return INVALID_SOCK_FD;
+
+      CNF_GetBindCommandAddress(family, &local_addr.ip_addr);
+      local_addr.port = port;
+      iface = CNF_GetBindCommandInterface();
+
+      sock_fd = SCK_OpenUdpSocket(NULL, &local_addr, iface, SCK_FLAG_RX_DEST_ADDR);
+      if (sock_fd < 0) {
+        LOG(LOGS_ERR, "Could not open command socket on %s",
+            UTI_IPSockAddrToString(&local_addr));
+        return INVALID_SOCK_FD;
+      }
+
+      if (family == IPADDR_INET4)
+        bound_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;
+
+      break;
+    case IPADDR_UNSPEC:
+      local_path = CNF_GetBindCommandPath();
+
+      sock_fd = SCK_OpenUnixDatagramSocket(NULL, local_path, 0);
+      if (sock_fd < 0) {
+        LOG(LOGS_ERR, "Could not open command socket on %s", local_path);
+        return INVALID_SOCK_FD;
+      }
+
+      break;
+    default:
+      assert(0);
+  }
+
+  /* Register handler for read events on the socket */
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_from_cmd_socket, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static void
+do_size_checks(void)
+{
+  int i, request_length, padding_length, reply_length;
+  CMD_Request request;
+  CMD_Reply reply;
+
+  assert(offsetof(CMD_Request, data) == 20);
+  assert(offsetof(CMD_Reply, data) == 28);
+
+  for (i = 0; i < N_REQUEST_TYPES; i++) {
+    request.version = PROTO_VERSION_NUMBER;
+    request.command = htons(i);
+    request_length = PKL_CommandLength(&request);
+    padding_length = PKL_CommandPaddingLength(&request);
+    if (padding_length > MAX_PADDING_LENGTH || padding_length > request_length ||
+        request_length > sizeof (CMD_Request) ||
+        (request_length && request_length < offsetof(CMD_Request, data)))
+      assert(0);
+  }
+
+  for (i = 1; i < N_REPLY_TYPES; i++) {
+    reply.reply = htons(i);
+    reply.status = STT_SUCCESS;
+    reply_length = PKL_ReplyLength(&reply);
+    if ((reply_length && reply_length < offsetof(CMD_Reply, data)) ||
+        reply_length > sizeof (CMD_Reply))
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+CAM_Initialise(void)
+{
+  assert(!initialised);
+  assert(sizeof (permissions) / sizeof (permissions[0]) == N_REQUEST_TYPES);
+  do_size_checks();
+
+  initialised = 1;
+
+  bound_sock_fd4 = 0;
+
+  sock_fdu = INVALID_SOCK_FD;
+  sock_fd4 = open_socket(IPADDR_INET4);
+  sock_fd6 = open_socket(IPADDR_INET6);
+
+  access_auth_table = ADF_CreateTable();
+}
+
+/* ================================================== */
+
+void
+CAM_Finalise(void)
+{
+  if (sock_fdu != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fdu);
+    SCK_RemoveSocket(sock_fdu);
+    SCK_CloseSocket(sock_fdu);
+    sock_fdu = INVALID_SOCK_FD;
+  }
+
+  if (sock_fd4 != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fd4);
+    SCK_CloseSocket(sock_fd4);
+    sock_fd4 = INVALID_SOCK_FD;
+  }
+
+  if (sock_fd6 != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fd6);
+    SCK_CloseSocket(sock_fd6);
+    sock_fd6 = INVALID_SOCK_FD;
+  }
+
+  ADF_DestroyTable(access_auth_table);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void
+CAM_OpenUnixSocket(void)
+{
+  /* This is separated from CAM_Initialise() as it needs to be called when
+     the process has already dropped the root privileges */
+  if (CNF_GetBindCommandPath())
+    sock_fdu = open_socket(IPADDR_UNSPEC);
+}
+
+/* ================================================== */
+
+static void
+transmit_reply(int sock_fd, int request_length, SCK_Message *message)
+{
+  message->length = PKL_ReplyLength((CMD_Reply *)message->data);
+
+  if (request_length < message->length) {
+    DEBUG_LOG("Response longer than request req_len=%d res_len=%d",
+              request_length, message->length);
+    return;
+  }
+
+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  if (message->addr_type == SCK_ADDR_IP &&
+      !SCK_IsLinkLocalIPAddress(&message->remote_addr.ip.ip_addr))
+    message->if_index = INVALID_IF_INDEX;
+
+#if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
+  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
+  if (message->addr_type == SCK_ADDR_IP && message->local_addr.ip.family == IPADDR_INET4 &&
+      (sock_fd != sock_fd4 || bound_sock_fd4))
+    message->local_addr.ip.family = IPADDR_UNSPEC;
+#endif
+
+  if (!SCK_SendMessage(sock_fd, message, 0))
+    return;
+}
+  
+/* ================================================== */
+
+static void
+handle_dump(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  SRC_DumpSources();
+  NSR_DumpAuthData();
+  NKS_DumpKeys();
+}
+
+/* ================================================== */
+
+static void
+handle_online(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.online.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.online.address, &address);
+  if (!NSR_SetConnectivity(&mask, &address, SRC_ONLINE))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_offline(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.offline.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.offline.address, &address);
+  if (!NSR_SetConnectivity(&mask, &address, SRC_OFFLINE))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_onoffline(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  address.family = mask.family = IPADDR_UNSPEC;
+  if (!NSR_SetConnectivity(&mask, &address, SRC_MAYBE_ONLINE))
+    ;
+}
+
+/* ================================================== */
+
+static void
+handle_burst(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.burst.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.burst.address, &address);
+  if (!NSR_InitiateSampleBurst(ntohl(rx_message->data.burst.n_good_samples),
+                               ntohl(rx_message->data.burst.n_total_samples),
+                               &mask, &address))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_minpoll(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMinpoll(&address,
+                         ntohl(rx_message->data.modify_minpoll.new_minpoll)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxpoll(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMaxpoll(&address,
+                         ntohl(rx_message->data.modify_minpoll.new_minpoll)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelay(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelay.address, &address);
+  if (!NSR_ModifyMaxdelay(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelay.new_max_delay)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelayratio(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelayratio.address, &address);
+  if (!NSR_ModifyMaxdelayratio(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelayratio.new_max_delay_ratio)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelaydevratio(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelaydevratio.address, &address);
+  if (!NSR_ModifyMaxdelaydevratio(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelaydevratio.new_max_delay_dev_ratio)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_minstratum(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMinstratum(&address,
+                            ntohl(rx_message->data.modify_minstratum.new_min_stratum)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_polltarget(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_polltarget.address, &address);
+  if (!NSR_ModifyPolltarget(&address,
+                            ntohl(rx_message->data.modify_polltarget.new_poll_target)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxupdateskew(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  REF_ModifyMaxupdateskew(UTI_FloatNetworkToHost(rx_message->data.modify_maxupdateskew.new_max_update_skew));
+}
+
+/* ================================================== */
+
+static void
+handle_modify_makestep(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  REF_ModifyMakestep(ntohl(rx_message->data.modify_makestep.limit),
+                     UTI_FloatNetworkToHost(rx_message->data.modify_makestep.threshold));
+}
+
+/* ================================================== */
+
+static void
+handle_settime(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec ts;
+  double offset, dfreq_ppm, new_afreq_ppm;
+  UTI_TimespecNetworkToHost(&rx_message->data.settime.ts, &ts);
+  if (!MNL_IsEnabled()) {
+    tx_message->status = htons(STT_NOTENABLED);
+  } else if (MNL_AcceptTimestamp(&ts, &offset, &dfreq_ppm, &new_afreq_ppm)) {
+    tx_message->reply = htons(RPY_MANUAL_TIMESTAMP2);
+    tx_message->data.manual_timestamp.offset = UTI_FloatHostToNetwork(offset);
+    tx_message->data.manual_timestamp.dfreq_ppm = UTI_FloatHostToNetwork(dfreq_ppm);
+    tx_message->data.manual_timestamp.new_afreq_ppm = UTI_FloatHostToNetwork(new_afreq_ppm);
+  } else {
+    tx_message->status = htons(STT_FAILED);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_local(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (ntohl(rx_message->data.local.on_off)) {
+    REF_EnableLocal(ntohl(rx_message->data.local.stratum),
+                    UTI_FloatNetworkToHost(rx_message->data.local.distance),
+                    ntohl(rx_message->data.local.orphan));
+  } else {
+    REF_DisableLocal();
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_manual(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int option;
+  option = ntohl(rx_message->data.manual.option);
+  switch (option) {
+    case 0:
+      MNL_Disable();
+      break;
+    case 1:
+      MNL_Enable();
+      break;
+    case 2:
+      MNL_Reset();
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_n_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int n_sources;
+  n_sources = SRC_ReadNumberOfSources();
+  tx_message->reply = htons(RPY_N_SOURCES);
+  tx_message->data.n_sources.n_sources = htonl(n_sources);
+}
+
+/* ================================================== */
+
+static void
+handle_source_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SourceReport report;
+  struct timespec now_corr;
+
+  /* Get data */
+  SCH_GetLastEventTime(&now_corr, NULL, NULL);
+  if (SRC_ReportSource(ntohl(rx_message->data.source_data.index), &report, &now_corr)) {
+    switch (SRC_GetType(ntohl(rx_message->data.source_data.index))) {
+      case SRC_NTP:
+        NSR_ReportSource(&report, &now_corr);
+        break;
+      case SRC_REFCLOCK:
+        RCL_ReportSource(&report, &now_corr);
+        break;
+    }
+    
+    tx_message->reply  = htons(RPY_SOURCE_DATA);
+    
+    UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.source_data.ip_addr);
+    tx_message->data.source_data.stratum = htons(report.stratum);
+    tx_message->data.source_data.poll    = htons(report.poll);
+    switch (report.state) {
+      case RPT_NONSELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_NONSELECTABLE);
+        break;
+      case RPT_FALSETICKER:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_FALSETICKER);
+        break;
+      case RPT_JITTERY:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_JITTERY);
+        break;
+      case RPT_SELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTABLE);
+        break;
+      case RPT_UNSELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_UNSELECTED);
+        break;
+      case RPT_SELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTED);
+        break;
+    }
+    switch (report.mode) {
+      case RPT_NTP_CLIENT:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_CLIENT);
+        break;
+      case RPT_NTP_PEER:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_PEER);
+        break;
+      case RPT_LOCAL_REFERENCE:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_REF);
+        break;
+    }
+    tx_message->data.source_data.flags = htons(0);
+    tx_message->data.source_data.reachability = htons(report.reachability);
+    tx_message->data.source_data.since_sample = htonl(report.latest_meas_ago);
+    tx_message->data.source_data.orig_latest_meas = UTI_FloatHostToNetwork(report.orig_latest_meas);
+    tx_message->data.source_data.latest_meas = UTI_FloatHostToNetwork(report.latest_meas);
+    tx_message->data.source_data.latest_meas_err = UTI_FloatHostToNetwork(report.latest_meas_err);
+  } else {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_rekey(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  KEY_Reload();
+  NKS_ReloadKeys();
+}
+
+/* ================================================== */
+
+static void
+handle_allowdeny(CMD_Request *rx_message, CMD_Reply *tx_message, int allow, int all)
+{
+  IPAddr ip;
+  int subnet_bits;
+
+  UTI_IPNetworkToHost(&rx_message->data.allow_deny.ip, &ip);
+  subnet_bits = ntohl(rx_message->data.allow_deny.subnet_bits);
+  if (!NCR_AddAccessRestriction(&ip, subnet_bits, allow, all))
+    tx_message->status = htons(STT_BADSUBNET);
+}
+
+/* ================================================== */
+
+static void
+handle_cmdallowdeny(CMD_Request *rx_message, CMD_Reply *tx_message, int allow, int all)
+{
+  IPAddr ip;
+  int subnet_bits;
+
+  UTI_IPNetworkToHost(&rx_message->data.allow_deny.ip, &ip);
+  subnet_bits = ntohl(rx_message->data.allow_deny.subnet_bits);
+  if (!CAM_AddAccessRestriction(&ip, subnet_bits, allow, all))
+    tx_message->status = htons(STT_BADSUBNET);
+}
+
+/* ================================================== */
+
+static void
+handle_accheck(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr ip;
+  UTI_IPNetworkToHost(&rx_message->data.ac_check.ip, &ip);
+  if (NCR_CheckAccessRestriction(&ip)) {
+    tx_message->status = htons(STT_ACCESSALLOWED);
+  } else {
+    tx_message->status = htons(STT_ACCESSDENIED);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_cmdaccheck(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr ip;
+  UTI_IPNetworkToHost(&rx_message->data.ac_check.ip, &ip);
+  if (CAM_CheckAccessRestriction(&ip)) {
+    tx_message->status = htons(STT_ACCESSALLOWED);
+  } else {
+    tx_message->status = htons(STT_ACCESSDENIED);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NTP_Source_Type type;
+  SourceParameters params;
+  NSR_Status status;
+  char *name;
+  int pool, port;
+  
+  switch (ntohl(rx_message->data.ntp_source.type)) {
+    case REQ_ADDSRC_SERVER:
+      type = NTP_SERVER;
+      pool = 0;
+      break;
+    case REQ_ADDSRC_PEER:
+      type = NTP_PEER;
+      pool = 0;
+      break;
+    case REQ_ADDSRC_POOL:
+      type = NTP_SERVER;
+      pool = 1;
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      return;
+  }
+
+  name = (char *)rx_message->data.ntp_source.name;
+
+  /* Make sure the name is terminated */
+  if (name[sizeof (rx_message->data.ntp_source.name) - 1] != '\0') {
+      tx_message->status = htons(STT_INVALIDNAME);
+      return;
+  }
+
+  port = ntohl(rx_message->data.ntp_source.port);
+  params.minpoll = ntohl(rx_message->data.ntp_source.minpoll);
+  params.maxpoll = ntohl(rx_message->data.ntp_source.maxpoll);
+  params.presend_minpoll = ntohl(rx_message->data.ntp_source.presend_minpoll);
+  params.min_stratum = ntohl(rx_message->data.ntp_source.min_stratum);
+  params.poll_target = ntohl(rx_message->data.ntp_source.poll_target);
+  params.version = ntohl(rx_message->data.ntp_source.version);
+  params.max_sources = ntohl(rx_message->data.ntp_source.max_sources);
+  params.min_samples = ntohl(rx_message->data.ntp_source.min_samples);
+  params.max_samples = ntohl(rx_message->data.ntp_source.max_samples);
+  params.filter_length = ntohl(rx_message->data.ntp_source.filter_length);
+  params.authkey = ntohl(rx_message->data.ntp_source.authkey);
+  params.nts_port = ntohl(rx_message->data.ntp_source.nts_port);
+  params.cert_set = ntohl(rx_message->data.ntp_source.cert_set);
+  params.max_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay);
+  params.max_delay_ratio =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_ratio);
+  params.max_delay_dev_ratio =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_dev_ratio);
+  params.max_delay_quant =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_quant);
+  params.min_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.min_delay);
+  params.asymmetry = UTI_FloatNetworkToHost(rx_message->data.ntp_source.asymmetry);
+  params.offset = UTI_FloatNetworkToHost(rx_message->data.ntp_source.offset);
+
+  params.connectivity = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_ONLINE ?
+                        SRC_ONLINE : SRC_OFFLINE;
+  params.auto_offline = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_AUTOOFFLINE ? 1 : 0;
+  params.iburst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_IBURST ? 1 : 0;
+  params.interleaved = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_INTERLEAVED ? 1 : 0;
+  params.burst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_BURST ? 1 : 0;
+  params.nts = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NTS ? 1 : 0;
+  params.copy = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_COPY ? 1 : 0;
+  params.ext_fields =
+    ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_EF_EXP1 ? NTP_EF_FLAG_EXP1 : 0;
+  params.sel_options =
+    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_PREFER ? SRC_SELECT_PREFER : 0) |
+    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NOSELECT ? SRC_SELECT_NOSELECT : 0) |
+    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_TRUST ? SRC_SELECT_TRUST : 0) |
+    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_REQUIRE ? SRC_SELECT_REQUIRE : 0);
+
+  status = NSR_AddSourceByName(name, port, pool, type, &params, NULL);
+  switch (status) {
+    case NSR_Success:
+      break;
+    case NSR_UnresolvedName:
+      /* Try to resolve the name now */
+      NSR_ResolveSources();
+      break;
+    case NSR_AlreadyInUse:
+      tx_message->status = htons(STT_SOURCEALREADYKNOWN);
+      break;
+    case NSR_TooManySources:
+      tx_message->status = htons(STT_TOOMANYSOURCES);
+      break;
+    case NSR_InvalidName:
+      tx_message->status = htons(STT_INVALIDNAME);
+      break;
+    case NSR_InvalidAF:
+    case NSR_NoSuchSource:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_del_source(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NSR_Status status;
+  IPAddr ip_addr;
+  
+  UTI_IPNetworkToHost(&rx_message->data.del_source.ip_addr, &ip_addr);
+  
+  status = NSR_RemoveSource(&ip_addr);
+  switch (status) {
+    case NSR_Success:
+      break;
+    case NSR_NoSuchSource:
+      tx_message->status = htons(STT_NOSUCHSOURCE);
+      break;
+    case NSR_TooManySources:
+    case NSR_AlreadyInUse:
+    case NSR_InvalidAF:
+    case NSR_InvalidName:
+    case NSR_UnresolvedName:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_writertc(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  switch (RTC_WriteParameters()) {
+    case RTC_ST_OK:
+      break;
+    case RTC_ST_NODRV:
+      tx_message->status = htons(STT_NORTC);
+      break;
+    case RTC_ST_BADFILE:
+      tx_message->status = htons(STT_BADRTCFILE);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_dfreq(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double dfreq;
+  dfreq = UTI_FloatNetworkToHost(rx_message->data.dfreq.dfreq);
+  LCL_AccumulateDeltaFrequency(dfreq * 1.0e-6);
+  LOG(LOGS_INFO, "Accumulated delta freq of %.3fppm", dfreq);
+}
+
+/* ================================================== */
+
+static void
+handle_doffset(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double doffset;
+
+  doffset = UTI_FloatNetworkToHost(rx_message->data.doffset.doffset);
+  if (!LCL_AccumulateOffset(doffset, 0.0)) {
+    tx_message->status = htons(STT_FAILED);
+  } else {
+    LOG(LOGS_INFO, "Accumulated delta offset of %.6f seconds", doffset);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_tracking(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_TrackingReport rpt;
+
+  REF_GetTrackingReport(&rpt);
+  tx_message->reply  = htons(RPY_TRACKING);
+  tx_message->data.tracking.ref_id = htonl(rpt.ref_id);
+  UTI_IPHostToNetwork(&rpt.ip_addr, &tx_message->data.tracking.ip_addr);
+  tx_message->data.tracking.stratum = htons(rpt.stratum);
+  tx_message->data.tracking.leap_status = htons(rpt.leap_status);
+  UTI_TimespecHostToNetwork(&rpt.ref_time, &tx_message->data.tracking.ref_time);
+  tx_message->data.tracking.current_correction = UTI_FloatHostToNetwork(rpt.current_correction);
+  tx_message->data.tracking.last_offset = UTI_FloatHostToNetwork(rpt.last_offset);
+  tx_message->data.tracking.rms_offset = UTI_FloatHostToNetwork(rpt.rms_offset);
+  tx_message->data.tracking.freq_ppm = UTI_FloatHostToNetwork(rpt.freq_ppm);
+  tx_message->data.tracking.resid_freq_ppm = UTI_FloatHostToNetwork(rpt.resid_freq_ppm);
+  tx_message->data.tracking.skew_ppm = UTI_FloatHostToNetwork(rpt.skew_ppm);
+  tx_message->data.tracking.root_delay = UTI_FloatHostToNetwork(rpt.root_delay);
+  tx_message->data.tracking.root_dispersion = UTI_FloatHostToNetwork(rpt.root_dispersion);
+  tx_message->data.tracking.last_update_interval = UTI_FloatHostToNetwork(rpt.last_update_interval);
+}
+
+/* ================================================== */
+
+static void
+handle_smoothing(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SmoothingReport report;
+  struct timespec now;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  if (!SMT_GetSmoothingReport(&report, &now)) {
+    tx_message->status = htons(STT_NOTENABLED);
+    return;
+  }
+
+  tx_message->reply  = htons(RPY_SMOOTHING);
+  tx_message->data.smoothing.flags = htonl((report.active ? RPY_SMT_FLAG_ACTIVE : 0) |
+                                           (report.leap_only ? RPY_SMT_FLAG_LEAPONLY : 0));
+  tx_message->data.smoothing.offset = UTI_FloatHostToNetwork(report.offset);
+  tx_message->data.smoothing.freq_ppm = UTI_FloatHostToNetwork(report.freq_ppm);
+  tx_message->data.smoothing.wander_ppm = UTI_FloatHostToNetwork(report.wander_ppm);
+  tx_message->data.smoothing.last_update_ago = UTI_FloatHostToNetwork(report.last_update_ago);
+  tx_message->data.smoothing.remaining_time = UTI_FloatHostToNetwork(report.remaining_time);
+}
+
+/* ================================================== */
+
+static void
+handle_smoothtime(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec now;
+  int option;
+
+  if (!SMT_IsEnabled()) {
+    tx_message->status = htons(STT_NOTENABLED);
+    return;
+  }
+
+  option = ntohl(rx_message->data.smoothtime.option);
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  switch (option) {
+    case REQ_SMOOTHTIME_RESET:
+      SMT_Reset(&now);
+      break;
+    case REQ_SMOOTHTIME_ACTIVATE:
+      SMT_Activate(&now);
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_sourcestats(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int status;
+  RPT_SourcestatsReport report;
+  struct timespec now_corr;
+
+  SCH_GetLastEventTime(&now_corr, NULL, NULL);
+  status = SRC_ReportSourcestats(ntohl(rx_message->data.sourcestats.index),
+                                 &report, &now_corr);
+
+  if (status) {
+    tx_message->reply = htons(RPY_SOURCESTATS);
+    tx_message->data.sourcestats.ref_id = htonl(report.ref_id);
+    UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.sourcestats.ip_addr);
+    tx_message->data.sourcestats.n_samples = htonl(report.n_samples);
+    tx_message->data.sourcestats.n_runs = htonl(report.n_runs);
+    tx_message->data.sourcestats.span_seconds = htonl(report.span_seconds);
+    tx_message->data.sourcestats.resid_freq_ppm = UTI_FloatHostToNetwork(report.resid_freq_ppm);
+    tx_message->data.sourcestats.skew_ppm = UTI_FloatHostToNetwork(report.skew_ppm);
+    tx_message->data.sourcestats.sd = UTI_FloatHostToNetwork(report.sd);
+    tx_message->data.sourcestats.est_offset = UTI_FloatHostToNetwork(report.est_offset);
+    tx_message->data.sourcestats.est_offset_err = UTI_FloatHostToNetwork(report.est_offset_err);
+  } else {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_rtcreport(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int status;
+  RPT_RTC_Report report;
+  status = RTC_GetReport(&report);
+  if (status) {
+    tx_message->reply  = htons(RPY_RTC);
+    UTI_TimespecHostToNetwork(&report.ref_time, &tx_message->data.rtc.ref_time);
+    tx_message->data.rtc.n_samples = htons(report.n_samples);
+    tx_message->data.rtc.n_runs = htons(report.n_runs);
+    tx_message->data.rtc.span_seconds = htonl(report.span_seconds);
+    tx_message->data.rtc.rtc_seconds_fast = UTI_FloatHostToNetwork(report.rtc_seconds_fast);
+    tx_message->data.rtc.rtc_gain_rate_ppm = UTI_FloatHostToNetwork(report.rtc_gain_rate_ppm);
+  } else {
+    tx_message->status = htons(STT_NORTC);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_trimrtc(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (!RTC_Trim())
+    tx_message->status = htons(STT_NORTC);
+}
+
+/* ================================================== */
+
+static void
+handle_cyclelogs(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  LOG_CycleLogFiles();
+}
+
+/* ================================================== */
+
+static void
+handle_client_accesses_by_index(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ClientAccessByIndex_Report report;
+  RPY_ClientAccesses_Client *client;
+  int n_indices;
+  uint32_t i, j, req_first_index, req_n_clients, req_min_hits, req_reset;
+  struct timespec now;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  req_first_index = ntohl(rx_message->data.client_accesses_by_index.first_index);
+  req_n_clients = ntohl(rx_message->data.client_accesses_by_index.n_clients);
+  if (req_n_clients > MAX_CLIENT_ACCESSES)
+    req_n_clients = MAX_CLIENT_ACCESSES;
+  req_min_hits = ntohl(rx_message->data.client_accesses_by_index.min_hits);
+  req_reset = ntohl(rx_message->data.client_accesses_by_index.reset);
+
+  n_indices = CLG_GetNumberOfIndices();
+  if (n_indices < 0) {
+    tx_message->status = htons(STT_INACTIVE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_CLIENT_ACCESSES_BY_INDEX3);
+  tx_message->data.client_accesses_by_index.n_indices = htonl(n_indices);
+
+  for (i = req_first_index, j = 0; i < (uint32_t)n_indices && j < req_n_clients; i++) {
+    if (!CLG_GetClientAccessReportByIndex(i, req_reset, req_min_hits, &report, &now))
+      continue;
+
+    client = &tx_message->data.client_accesses_by_index.clients[j++];
+
+    UTI_IPHostToNetwork(&report.ip_addr, &client->ip);
+    client->ntp_hits = htonl(report.ntp_hits);
+    client->nke_hits = htonl(report.nke_hits);
+    client->cmd_hits = htonl(report.cmd_hits);
+    client->ntp_drops = htonl(report.ntp_drops);
+    client->nke_drops = htonl(report.nke_drops);
+    client->cmd_drops = htonl(report.cmd_drops);
+    client->ntp_interval = report.ntp_interval;
+    client->nke_interval = report.nke_interval;
+    client->cmd_interval = report.cmd_interval;
+    client->ntp_timeout_interval = report.ntp_timeout_interval;
+    client->last_ntp_hit_ago = htonl(report.last_ntp_hit_ago);
+    client->last_nke_hit_ago = htonl(report.last_nke_hit_ago);
+    client->last_cmd_hit_ago = htonl(report.last_cmd_hit_ago);
+  }
+
+  tx_message->data.client_accesses_by_index.next_index = htonl(i);
+  tx_message->data.client_accesses_by_index.n_clients = htonl(j);
+}
+
+/* ================================================== */
+
+static void
+handle_manual_list(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int n_samples;
+  int i;
+  RPY_ManualListSample *sample;
+  RPT_ManualSamplesReport report[MAX_MANUAL_LIST_SAMPLES];
+
+  tx_message->reply = htons(RPY_MANUAL_LIST2);
+  
+  MNL_ReportSamples(report, MAX_MANUAL_LIST_SAMPLES, &n_samples);
+  tx_message->data.manual_list.n_samples = htonl(n_samples);
+
+  for (i=0; i<n_samples; i++) {
+    sample = &tx_message->data.manual_list.samples[i];
+    UTI_TimespecHostToNetwork(&report[i].when, &sample->when);
+    sample->slewed_offset = UTI_FloatHostToNetwork(report[i].slewed_offset);
+    sample->orig_offset = UTI_FloatHostToNetwork(report[i].orig_offset);
+    sample->residual = UTI_FloatHostToNetwork(report[i].residual);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_manual_delete(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int index;
+
+  index = ntohl(rx_message->data.manual_delete.index);
+  if (!MNL_DeleteSample(index))
+    tx_message->status = htons(STT_BADSAMPLE);
+}  
+
+/* ================================================== */
+
+static void
+handle_make_step(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (!LCL_MakeStep())
+    tx_message->status = htons(STT_FAILED);
+}
+
+/* ================================================== */
+
+static void
+handle_activity(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ActivityReport report;
+  NSR_GetActivityReport(&report);
+  tx_message->data.activity.online = htonl(report.online);
+  tx_message->data.activity.offline = htonl(report.offline);
+  tx_message->data.activity.burst_online = htonl(report.burst_online);
+  tx_message->data.activity.burst_offline = htonl(report.burst_offline);
+  tx_message->data.activity.unresolved = htonl(report.unresolved);
+  tx_message->reply = htons(RPY_ACTIVITY);
+}
+
+/* ================================================== */
+
+static void
+handle_reselect_distance(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double dist;
+  dist = UTI_FloatNetworkToHost(rx_message->data.reselect_distance.distance);
+  SRC_SetReselectDistance(dist);
+}
+
+/* ================================================== */
+
+static void
+handle_reselect(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  SRC_ReselectSource();
+}
+
+/* ================================================== */
+
+static void
+handle_refresh(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NSR_RefreshAddresses();
+}
+
+/* ================================================== */
+
+static void
+handle_server_stats(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ServerStatsReport report;
+
+  CLG_GetServerStatsReport(&report);
+  tx_message->reply = htons(RPY_SERVER_STATS3);
+  tx_message->data.server_stats.ntp_hits = htonl(report.ntp_hits);
+  tx_message->data.server_stats.nke_hits = htonl(report.nke_hits);
+  tx_message->data.server_stats.cmd_hits = htonl(report.cmd_hits);
+  tx_message->data.server_stats.ntp_drops = htonl(report.ntp_drops);
+  tx_message->data.server_stats.nke_drops = htonl(report.nke_drops);
+  tx_message->data.server_stats.cmd_drops = htonl(report.cmd_drops);
+  tx_message->data.server_stats.log_drops = htonl(report.log_drops);
+  tx_message->data.server_stats.ntp_auth_hits = htonl(report.ntp_auth_hits);
+  tx_message->data.server_stats.ntp_interleaved_hits = htonl(report.ntp_interleaved_hits);
+  tx_message->data.server_stats.ntp_timestamps = htonl(report.ntp_timestamps);
+  tx_message->data.server_stats.ntp_span_seconds = htonl(report.ntp_span_seconds);
+}
+
+/* ================================================== */
+
+static void
+handle_ntp_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_NTPReport report;
+
+  UTI_IPNetworkToHost(&rx_message->data.ntp_data.ip_addr, &report.remote_addr);
+
+  if (!NSR_GetNTPReport(&report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_NTP_DATA);
+  UTI_IPHostToNetwork(&report.remote_addr, &tx_message->data.ntp_data.remote_addr);
+  UTI_IPHostToNetwork(&report.local_addr, &tx_message->data.ntp_data.local_addr);
+  tx_message->data.ntp_data.remote_port = htons(report.remote_port);
+  tx_message->data.ntp_data.leap = report.leap;
+  tx_message->data.ntp_data.version = report.version;
+  tx_message->data.ntp_data.mode = report.mode;
+  tx_message->data.ntp_data.stratum = report.stratum;
+  tx_message->data.ntp_data.poll = report.poll;
+  tx_message->data.ntp_data.precision = report.precision;
+  tx_message->data.ntp_data.root_delay = UTI_FloatHostToNetwork(report.root_delay);
+  tx_message->data.ntp_data.root_dispersion = UTI_FloatHostToNetwork(report.root_dispersion);
+  tx_message->data.ntp_data.ref_id = htonl(report.ref_id);
+  UTI_TimespecHostToNetwork(&report.ref_time, &tx_message->data.ntp_data.ref_time);
+  tx_message->data.ntp_data.offset = UTI_FloatHostToNetwork(report.offset);
+  tx_message->data.ntp_data.peer_delay = UTI_FloatHostToNetwork(report.peer_delay);
+  tx_message->data.ntp_data.peer_dispersion = UTI_FloatHostToNetwork(report.peer_dispersion);
+  tx_message->data.ntp_data.response_time = UTI_FloatHostToNetwork(report.response_time);
+  tx_message->data.ntp_data.jitter_asymmetry = UTI_FloatHostToNetwork(report.jitter_asymmetry);
+  tx_message->data.ntp_data.flags = htons((report.tests & RPY_NTP_FLAGS_TESTS) |
+                                          (report.interleaved ? RPY_NTP_FLAG_INTERLEAVED : 0) |
+                                          (report.authenticated ? RPY_NTP_FLAG_AUTHENTICATED : 0));
+  tx_message->data.ntp_data.tx_tss_char = report.tx_tss_char;
+  tx_message->data.ntp_data.rx_tss_char = report.rx_tss_char;
+  tx_message->data.ntp_data.total_tx_count = htonl(report.total_tx_count);
+  tx_message->data.ntp_data.total_rx_count = htonl(report.total_rx_count);
+  tx_message->data.ntp_data.total_valid_count = htonl(report.total_valid_count);
+  tx_message->data.ntp_data.total_good_count = htonl(report.total_good_count);
+  memset(tx_message->data.ntp_data.reserved, 0xff, sizeof (tx_message->data.ntp_data.reserved));
+}
+
+/* ================================================== */
+
+static void
+handle_shutdown(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  LOG(LOGS_INFO, "Received shutdown command");
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+handle_ntp_source_name(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr addr;
+  char *name;
+
+  UTI_IPNetworkToHost(&rx_message->data.ntp_source_name.ip_addr, &addr);
+  name = NSR_GetName(&addr);
+
+  if (!name) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_NTP_SOURCE_NAME);
+
+  /* Avoid compiler warning */
+  if (strlen(name) >= sizeof (tx_message->data.ntp_source_name.name))
+    memcpy(tx_message->data.ntp_source_name.name, name,
+           sizeof (tx_message->data.ntp_source_name.name));
+  else
+    strncpy((char *)tx_message->data.ntp_source_name.name, name,
+            sizeof (tx_message->data.ntp_source_name.name));
+}
+
+/* ================================================== */
+
+static void
+handle_reload_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  CNF_ReloadSources();
+}
+
+/* ================================================== */
+
+static void
+handle_reset_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec cooked_now, now;
+
+  SRC_ResetSources();
+  SCH_GetLastEventTime(&cooked_now, NULL, &now);
+  LCL_NotifyExternalTimeStep(&now, &cooked_now, 0.0, 0.0);
+}
+
+/* ================================================== */
+
+static void
+handle_auth_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_AuthReport report;
+  IPAddr ip_addr;
+
+  UTI_IPNetworkToHost(&rx_message->data.auth_data.ip_addr, &ip_addr);
+
+  if (!NSR_GetAuthReport(&ip_addr, &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_AUTH_DATA);
+
+  switch (report.mode) {
+    case NTP_AUTH_NONE:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NONE);
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_SYMMETRIC);
+      break;
+    case NTP_AUTH_NTS:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NTS);
+      break;
+    default:
+      break;
+  }
+
+  tx_message->data.auth_data.key_type = htons(report.key_type);
+  tx_message->data.auth_data.key_id = htonl(report.key_id);
+  tx_message->data.auth_data.key_length = htons(report.key_length);
+  tx_message->data.auth_data.ke_attempts = htons(report.ke_attempts);
+  tx_message->data.auth_data.last_ke_ago = htonl(report.last_ke_ago);
+  tx_message->data.auth_data.cookies = htons(report.cookies);
+  tx_message->data.auth_data.cookie_length = htons(report.cookie_length);
+  tx_message->data.auth_data.nak = htons(report.nak);
+}
+
+/* ================================================== */
+
+static uint16_t
+convert_select_options(int options)
+{
+  return (options & SRC_SELECT_PREFER ? RPY_SD_OPTION_PREFER : 0) |
+         (options & SRC_SELECT_NOSELECT ? RPY_SD_OPTION_NOSELECT : 0) |
+         (options & SRC_SELECT_TRUST ? RPY_SD_OPTION_TRUST : 0) |
+         (options & SRC_SELECT_REQUIRE ? RPY_SD_OPTION_REQUIRE : 0);
+}
+
+/* ================================================== */
+
+static void
+handle_select_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SelectReport report;
+
+  if (!SRC_GetSelectReport(ntohl(rx_message->data.select_data.index), &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_SELECT_DATA);
+
+  tx_message->data.select_data.ref_id = htonl(report.ref_id);
+  UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.select_data.ip_addr);
+  tx_message->data.select_data.state_char = report.state_char;
+  tx_message->data.select_data.authentication = report.authentication;
+  tx_message->data.select_data.leap = report.leap;
+  tx_message->data.select_data.conf_options = htons(convert_select_options(report.conf_options));
+  tx_message->data.select_data.eff_options = htons(convert_select_options(report.eff_options));
+  tx_message->data.select_data.last_sample_ago = htonl(report.last_sample_ago);
+  tx_message->data.select_data.score = UTI_FloatHostToNetwork(report.score);
+  tx_message->data.select_data.hi_limit = UTI_FloatHostToNetwork(report.hi_limit);
+  tx_message->data.select_data.lo_limit = UTI_FloatHostToNetwork(report.lo_limit);
+}
+
+/* ================================================== */
+/* Read a packet and process it */
+
+static void
+read_from_cmd_socket(int sock_fd, int event, void *anything)
+{
+  SCK_Message *sck_message;
+  CMD_Request rx_message;
+  CMD_Reply tx_message;
+  IPAddr loopback_addr, remote_ip;
+  int read_length, expected_length;
+  int localhost, allowed, log_index;
+  uint16_t rx_command;
+  struct timespec now, cooked_now;
+
+  sck_message = SCK_ReceiveMessage(sock_fd, 0);
+  if (!sck_message)
+    return;
+
+  read_length = sck_message->length;
+
+  /* Get current time cheaply */
+  SCH_GetLastEventTime(&cooked_now, NULL, &now);
+
+  /* Check if it's from localhost (127.0.0.1, ::1, or Unix domain),
+     or an authorised address */
+  switch (sck_message->addr_type) {
+    case SCK_ADDR_IP:
+      assert(sock_fd == sock_fd4 || sock_fd == sock_fd6);
+      remote_ip = sck_message->remote_addr.ip.ip_addr;
+      SCK_GetLoopbackIPAddress(remote_ip.family, &loopback_addr);
+      localhost = UTI_CompareIPs(&remote_ip, &loopback_addr, NULL) == 0;
+
+      if (!localhost && !ADF_IsAllowed(access_auth_table, &remote_ip)) {
+        DEBUG_LOG("Unauthorised host %s",
+                  UTI_IPSockAddrToString(&sck_message->remote_addr.ip));
+        return;
+      }
+
+      assert(remote_ip.family != IPADDR_UNSPEC);
+
+      break;
+    case SCK_ADDR_UNIX:
+      assert(sock_fd == sock_fdu);
+      remote_ip.family = IPADDR_UNSPEC;
+      localhost = 1;
+      break;
+    default:
+      DEBUG_LOG("Unexpected address type");
+      return;
+  }
+
+  if (read_length < offsetof(CMD_Request, data) ||
+      read_length < offsetof(CMD_Reply, data) ||
+      read_length > sizeof (CMD_Request)) {
+    /* We don't know how to process anything like this or an error reply
+       would be larger than the request */
+    DEBUG_LOG("Unexpected length");
+    return;
+  }
+
+  memcpy(&rx_message, sck_message->data, read_length);
+
+  if (rx_message.pkt_type != PKT_TYPE_CMD_REQUEST ||
+      rx_message.res1 != 0 ||
+      rx_message.res2 != 0) {
+    DEBUG_LOG("Command packet dropped");
+    return;
+  }
+
+  log_index = CLG_LogServiceAccess(CLG_CMDMON, &remote_ip, &cooked_now);
+
+  /* Don't reply to all requests from hosts other than localhost if the rate
+     is excessive */
+  if (!localhost && log_index >= 0 && CLG_LimitServiceRate(CLG_CMDMON, log_index)) {
+      DEBUG_LOG("Command packet discarded to limit response rate");
+      return;
+  }
+
+  expected_length = PKL_CommandLength(&rx_message);
+  rx_command = ntohs(rx_message.command);
+
+  memset(&tx_message, 0, sizeof (tx_message));
+  sck_message->data = &tx_message;
+  sck_message->length = 0;
+
+  tx_message.version = PROTO_VERSION_NUMBER;
+  tx_message.pkt_type = PKT_TYPE_CMD_REPLY;
+  tx_message.command = rx_message.command;
+  tx_message.reply = htons(RPY_NULL);
+  tx_message.status = htons(STT_SUCCESS);
+  tx_message.sequence = rx_message.sequence;
+
+  if (rx_message.version != PROTO_VERSION_NUMBER) {
+    DEBUG_LOG("Command packet has invalid version (%d != %d)",
+              rx_message.version, PROTO_VERSION_NUMBER);
+
+    if (rx_message.version >= PROTO_VERSION_MISMATCH_COMPAT_SERVER) {
+      tx_message.status = htons(STT_BADPKTVERSION);
+      transmit_reply(sock_fd, read_length, sck_message);
+    }
+    return;
+  }
+
+  if (rx_command >= N_REQUEST_TYPES ||
+      expected_length < (int)offsetof(CMD_Request, data)) {
+    DEBUG_LOG("Command packet has invalid command %d", rx_command);
+
+    tx_message.status = htons(STT_INVALID);
+    transmit_reply(sock_fd, read_length, sck_message);
+    return;
+  }
+
+  if (read_length < expected_length) {
+    DEBUG_LOG("Command packet is too short (%d < %d)", read_length,
+              expected_length);
+
+    tx_message.status = htons(STT_BADPKTLENGTH);
+    transmit_reply(sock_fd, read_length, sck_message);
+    return;
+  }
+
+  /* OK, we have a valid message.  Now dispatch on message type and process it. */
+
+  if (rx_command >= N_REQUEST_TYPES) {
+    /* This should be already handled */
+    assert(0);
+  } else {
+    /* Check level of authority required to issue the command.  All commands
+       from the Unix domain socket (which is accessible only by the root and
+       chrony user/group) are allowed. */
+    if (remote_ip.family == IPADDR_UNSPEC) {
+      assert(sock_fd == sock_fdu);
+      allowed = 1;
+    } else {
+      switch (permissions[rx_command]) {
+        case PERMIT_AUTH:
+          allowed = 0;
+          break;
+        case PERMIT_LOCAL:
+          allowed = localhost;
+          break;
+        case PERMIT_OPEN:
+          allowed = 1;
+          break;
+        default:
+          assert(0);
+          allowed = 0;
+      }
+    }
+
+    if (allowed) {
+      switch(rx_command) {
+        case REQ_NULL:
+          /* Do nothing */
+          break;
+
+        case REQ_DUMP:
+          handle_dump(&rx_message, &tx_message);
+          break;
+
+        case REQ_ONLINE:
+          handle_online(&rx_message, &tx_message);
+          break;
+
+        case REQ_OFFLINE:
+          handle_offline(&rx_message, &tx_message);
+          break;
+
+        case REQ_BURST:
+          handle_burst(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MINPOLL:
+          handle_modify_minpoll(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXPOLL:
+          handle_modify_maxpoll(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAY:
+          handle_modify_maxdelay(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAYRATIO:
+          handle_modify_maxdelayratio(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAYDEVRATIO:
+          handle_modify_maxdelaydevratio(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXUPDATESKEW:
+          handle_modify_maxupdateskew(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAKESTEP:
+          handle_modify_makestep(&rx_message, &tx_message);
+          break;
+
+        case REQ_LOGON:
+          /* Authentication is no longer supported, log-on always fails */
+          tx_message.status = htons(STT_FAILED);
+          break;
+
+        case REQ_SETTIME:
+          handle_settime(&rx_message, &tx_message);
+          break;
+        
+        case REQ_LOCAL2:
+          handle_local(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL:
+          handle_manual(&rx_message, &tx_message);
+          break;
+
+        case REQ_N_SOURCES:
+          handle_n_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_SOURCE_DATA:
+          handle_source_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_REKEY:
+          handle_rekey(&rx_message, &tx_message);
+          break;
+
+        case REQ_ALLOW:
+          handle_allowdeny(&rx_message, &tx_message, 1, 0);
+          break;
+
+        case REQ_ALLOWALL:
+          handle_allowdeny(&rx_message, &tx_message, 1, 1);
+          break;
+
+        case REQ_DENY:
+          handle_allowdeny(&rx_message, &tx_message, 0, 0);
+          break;
+
+        case REQ_DENYALL:
+          handle_allowdeny(&rx_message, &tx_message, 0, 1);
+          break;
+
+        case REQ_CMDALLOW:
+          handle_cmdallowdeny(&rx_message, &tx_message, 1, 0);
+          break;
+
+        case REQ_CMDALLOWALL:
+          handle_cmdallowdeny(&rx_message, &tx_message, 1, 1);
+          break;
+
+        case REQ_CMDDENY:
+          handle_cmdallowdeny(&rx_message, &tx_message, 0, 0);
+          break;
+
+        case REQ_CMDDENYALL:
+          handle_cmdallowdeny(&rx_message, &tx_message, 0, 1);
+          break;
+
+        case REQ_ACCHECK:
+          handle_accheck(&rx_message, &tx_message);
+          break;
+
+        case REQ_CMDACCHECK:
+          handle_cmdaccheck(&rx_message, &tx_message);
+          break;
+
+        case REQ_ADD_SOURCE:
+          handle_add_source(&rx_message, &tx_message);
+          break;
+
+        case REQ_DEL_SOURCE:
+          handle_del_source(&rx_message, &tx_message);
+          break;
+
+        case REQ_WRITERTC:
+          handle_writertc(&rx_message, &tx_message);
+          break;
+          
+        case REQ_DFREQ:
+          handle_dfreq(&rx_message, &tx_message);
+          break;
+
+        case REQ_DOFFSET2:
+          handle_doffset(&rx_message, &tx_message);
+          break;
+
+        case REQ_TRACKING:
+          handle_tracking(&rx_message, &tx_message);
+          break;
+
+        case REQ_SMOOTHING:
+          handle_smoothing(&rx_message, &tx_message);
+          break;
+
+        case REQ_SMOOTHTIME:
+          handle_smoothtime(&rx_message, &tx_message);
+          break;
+
+        case REQ_SOURCESTATS:
+          handle_sourcestats(&rx_message, &tx_message);
+          break;
+
+        case REQ_RTCREPORT:
+          handle_rtcreport(&rx_message, &tx_message);
+          break;
+          
+        case REQ_TRIMRTC:
+          handle_trimrtc(&rx_message, &tx_message);
+          break;
+
+        case REQ_CYCLELOGS:
+          handle_cyclelogs(&rx_message, &tx_message);
+          break;
+
+        case REQ_CLIENT_ACCESSES_BY_INDEX3:
+          handle_client_accesses_by_index(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL_LIST:
+          handle_manual_list(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL_DELETE:
+          handle_manual_delete(&rx_message, &tx_message);
+          break;
+
+        case REQ_MAKESTEP:
+          handle_make_step(&rx_message, &tx_message);
+          break;
+
+        case REQ_ACTIVITY:
+          handle_activity(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESELECTDISTANCE:
+          handle_reselect_distance(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESELECT:
+          handle_reselect(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MINSTRATUM:
+          handle_modify_minstratum(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_POLLTARGET:
+          handle_modify_polltarget(&rx_message, &tx_message);
+          break;
+
+        case REQ_REFRESH:
+          handle_refresh(&rx_message, &tx_message);
+          break;
+
+        case REQ_SERVER_STATS:
+          handle_server_stats(&rx_message, &tx_message);
+          break;
+
+        case REQ_NTP_DATA:
+          handle_ntp_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_SHUTDOWN:
+          handle_shutdown(&rx_message, &tx_message);
+          break;
+
+        case REQ_ONOFFLINE:
+          handle_onoffline(&rx_message, &tx_message);
+          break;
+
+        case REQ_NTP_SOURCE_NAME:
+          handle_ntp_source_name(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESET_SOURCES:
+          handle_reset_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_AUTH_DATA:
+          handle_auth_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_SELECT_DATA:
+          handle_select_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_RELOAD_SOURCES:
+          handle_reload_sources(&rx_message, &tx_message);
+          break;
+
+        default:
+          DEBUG_LOG("Unhandled command %d", rx_command);
+          tx_message.status = htons(STT_FAILED);
+          break;
+      }
+    } else {
+      tx_message.status = htons(STT_UNAUTH);
+    }
+  }
+
+  /* Transmit the response */
+  transmit_reply(sock_fd, read_length, sck_message);
+}
+
+/* ================================================== */
+
+int
+CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+ {
+  ADF_Status status;
+
+  if (allow) {
+    if (all) {
+      status = ADF_AllowAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Allow(access_auth_table, ip_addr, subnet_bits);
+    }
+  } else {
+    if (all) {
+      status = ADF_DenyAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Deny(access_auth_table, ip_addr, subnet_bits);
+    }
+  }
+
+  if (status == ADF_BADSUBNET) {
+    return 0;
+  } else if (status == ADF_SUCCESS) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+CAM_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return ADF_IsAllowed(access_auth_table, ip_addr);
+}
+
+
+/* ================================================== */
+/* ================================================== */
diff --git a/cmdmon.h b/cmdmon.h
new file mode 100644
index 0000000..86356b9
--- /dev/null
+++ b/cmdmon.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the control and monitoring module in the software
+  */
+
+#ifndef GOT_CMDMON_H
+#define GOT_CMDMON_H
+
+#include "addressing.h"
+
+extern void CAM_Initialise(void);
+
+extern void CAM_Finalise(void);
+
+extern void CAM_OpenUnixSocket(void);
+extern int CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all);
+extern int CAM_CheckAccessRestriction(IPAddr *ip_addr);
+
+#endif /* GOT_CMDMON_H */
diff --git a/cmdparse.c b/cmdparse.c
new file mode 100644
index 0000000..1a9e210
--- /dev/null
+++ b/cmdparse.c
@@ -0,0 +1,398 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2013-2014, 2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+  
+  Module for parsing various forms of directive and command lines that
+  are common to the configuration file and to the command client.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "cmdparse.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "ntp.h"
+#include "util.h"
+
+/* ================================================== */
+
+int
+CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
+{
+  char *hostname, *cmd;
+  uint32_t ef_type;
+  int n;
+  
+  src->port = SRC_DEFAULT_PORT;
+  src->params.minpoll = SRC_DEFAULT_MINPOLL;
+  src->params.maxpoll = SRC_DEFAULT_MAXPOLL;
+  src->params.connectivity = SRC_ONLINE;
+  src->params.auto_offline = 0;
+  src->params.presend_minpoll = SRC_DEFAULT_PRESEND_MINPOLL;
+  src->params.burst = 0;
+  src->params.iburst = 0;
+  src->params.min_stratum = SRC_DEFAULT_MINSTRATUM;
+  src->params.poll_target = SRC_DEFAULT_POLLTARGET;
+  src->params.version = 0;
+  src->params.max_sources = SRC_DEFAULT_MAXSOURCES;
+  src->params.min_samples = SRC_DEFAULT_MINSAMPLES;
+  src->params.max_samples = SRC_DEFAULT_MAXSAMPLES;
+  src->params.filter_length = 0;
+  src->params.interleaved = 0;
+  src->params.sel_options = 0;
+  src->params.nts = 0;
+  src->params.nts_port = SRC_DEFAULT_NTSPORT;
+  src->params.copy = 0;
+  src->params.ext_fields = 0;
+  src->params.authkey = INACTIVE_AUTHKEY;
+  src->params.cert_set = SRC_DEFAULT_CERTSET;
+  src->params.max_delay = SRC_DEFAULT_MAXDELAY;
+  src->params.max_delay_ratio = SRC_DEFAULT_MAXDELAYRATIO;
+  src->params.max_delay_dev_ratio = SRC_DEFAULT_MAXDELAYDEVRATIO;
+  src->params.max_delay_quant = 0.0;
+  src->params.min_delay = 0.0;
+  src->params.asymmetry = SRC_DEFAULT_ASYMMETRY;
+  src->params.offset = 0.0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (!*hostname)
+    return 0;
+
+  src->name = hostname;
+
+  /* Parse options */
+  for (; *line; line += n) {
+    cmd = line;
+    line = CPS_SplitWord(line);
+    n = 0;
+
+    if (!strcasecmp(cmd, "auto_offline")) {
+      src->params.auto_offline = 1;
+    } else if (!strcasecmp(cmd, "burst")) {
+      src->params.burst = 1;
+    } else if (!strcasecmp(cmd, "copy")) {
+      src->params.copy = 1;
+    } else if (!strcasecmp(cmd, "iburst")) {
+      src->params.iburst = 1;
+    } else if (!strcasecmp(cmd, "offline")) {
+      src->params.connectivity = SRC_OFFLINE;
+    } else if (!strcasecmp(cmd, "noselect")) {
+      src->params.sel_options |= SRC_SELECT_NOSELECT;
+    } else if (!strcasecmp(cmd, "prefer")) {
+      src->params.sel_options |= SRC_SELECT_PREFER;
+    } else if (!strcasecmp(cmd, "require")) {
+      src->params.sel_options |= SRC_SELECT_REQUIRE;
+    } else if (!strcasecmp(cmd, "trust")) {
+      src->params.sel_options |= SRC_SELECT_TRUST;
+    } else if (!strcasecmp(cmd, "certset")) {
+      if (sscanf(line, "%"SCNu32"%n", &src->params.cert_set, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "key")) {
+      if (sscanf(line, "%"SCNu32"%n", &src->params.authkey, &n) != 1 ||
+          src->params.authkey == INACTIVE_AUTHKEY)
+        return 0;
+    } else if (!strcasecmp(cmd, "asymmetry")) {
+      if (sscanf(line, "%lf%n", &src->params.asymmetry, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "extfield")) {
+      if (sscanf(line, "%"SCNx32"%n", &ef_type, &n) != 1)
+        return 0;
+      switch (ef_type) {
+        case NTP_EF_EXP1:
+          src->params.ext_fields |= NTP_EF_FLAG_EXP1;
+          break;
+        default:
+          return 0;
+      }
+    } else if (!strcasecmp(cmd, "filter")) {
+      if (sscanf(line, "%d%n", &src->params.filter_length, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelay")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelayratio")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_ratio, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelaydevratio")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_dev_ratio, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelayquant")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_quant, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxpoll")) {
+      if (sscanf(line, "%d%n", &src->params.maxpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxsamples")) {
+      if (sscanf(line, "%d%n", &src->params.max_samples, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxsources")) {
+      if (sscanf(line, "%d%n", &src->params.max_sources, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "mindelay")) {
+      if (sscanf(line, "%lf%n", &src->params.min_delay, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minpoll")) {
+      if (sscanf(line, "%d%n", &src->params.minpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minsamples")) {
+      if (sscanf(line, "%d%n", &src->params.min_samples, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minstratum")) {
+      if (sscanf(line, "%d%n", &src->params.min_stratum, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "nts")) {
+      src->params.nts = 1;
+    } else if (!strcasecmp(cmd, "ntsport")) {
+      if (sscanf(line, "%d%n", &src->params.nts_port, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "offset")) {
+      if (sscanf(line, "%lf%n", &src->params.offset, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "port")) {
+      if (sscanf(line, "%d%n", &src->port, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "polltarget")) {
+      if (sscanf(line, "%d%n", &src->params.poll_target, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "presend")) {
+      if (sscanf(line, "%d%n", &src->params.presend_minpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "version")) {
+      if (sscanf(line, "%d%n", &src->params.version, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "xleave")) {
+      src->params.interleaved = 1;
+    } else {
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits)
+{
+  char *p, *net, *slash;
+  uint32_t a, b, c;
+  int bits, len, n;
+
+  p = CPS_SplitWord(line);
+
+  if (strcmp(line, "all") == 0) {
+    *all = 1;
+    net = p;
+    p = CPS_SplitWord(p);
+  } else {
+    *all = 0;
+    net = line;
+  }
+
+  /* Make sure there are no other arguments */
+  if (*p)
+    return 0;
+
+  /* No specified address or network means all IPv4 and IPv6 addresses */
+  if (!*net) {
+    ip->family = IPADDR_UNSPEC;
+    *subnet_bits = 0;
+    return 1;
+  }
+
+  slash = strchr(net, '/');
+  if (slash) {
+    if (sscanf(slash + 1, "%d%n", &bits, &len) != 1 || slash[len + 1] || bits < 0)
+      return 0;
+    *slash = '\0';
+  } else {
+    bits = -1;
+  }
+
+  if (UTI_StringToIP(net, ip)) {
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  /* Check for a shortened IPv4 network notation using only 1, 2, or 3 decimal
+     numbers.  This is different than the numbers-and-dots notation accepted
+     by inet_aton()! */
+
+  a = b = c = 0;
+  n = sscanf(net, "%"PRIu32"%n.%"PRIu32"%n.%"PRIu32"%n", &a, &len, &b, &len, &c, &len);
+
+  if (n > 0 && !net[len]) {
+    if (a > 255 || b > 255 || c > 255)
+      return 0;
+
+    ip->family = IPADDR_INET4;
+    ip->addr.in4 = (a << 24) | (b << 16) | (c << 8);
+
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = n * 8;
+
+    return 1;
+  }
+
+  /* The last possibility is a hostname */
+  if (bits < 0 && DNS_Name2IPAddress(net, ip, 1) == DNS_Success) {
+    *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance)
+{
+  int n;
+  char *cmd;
+
+  *stratum = 10;
+  *distance = 1.0;
+  *orphan = 0;
+
+  while (*line) {
+    cmd = line;
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(cmd, "stratum")) {
+      if (sscanf(line, "%d%n", stratum, &n) != 1 ||
+          *stratum >= NTP_MAX_STRATUM || *stratum <= 0)
+        return 0;
+    } else if (!strcasecmp(cmd, "orphan")) {
+      *orphan = 1;
+      n = 0;
+    } else if (!strcasecmp(cmd, "distance")) {
+      if (sscanf(line, "%lf%n", distance, &n) != 1)
+        return 0;
+    } else {
+      return 0;
+    }
+
+    line += n;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CPS_NormalizeLine(char *line)
+{
+  char *p, *q;
+  int space = 1, first = 1;
+
+  /* Remove white-space at beginning and replace white-spaces with space char */
+  for (p = q = line; *p; p++) {
+    if (isspace((unsigned char)*p)) {
+      if (!space)
+        *q++ = ' ';
+      space = 1;
+      continue;
+    }
+
+    /* Discard comment lines */
+    if (first && strchr("!;#%", *p))
+      break;
+
+    *q++ = *p;
+    space = first = 0;
+  }
+
+  /* Strip trailing space */
+  if (q > line && q[-1] == ' ')
+    q--;
+
+  *q = '\0';
+}
+
+/* ================================================== */
+
+char *
+CPS_SplitWord(char *line)
+{
+  char *p = line, *q = line;
+
+  /* Skip white-space before the word */
+  while (*q && isspace((unsigned char)*q))
+    q++;
+
+  /* Move the word to the beginning */
+  while (*q && !isspace((unsigned char)*q))
+    *p++ = *q++;
+
+  /* Find the next word */
+  while (*q && isspace((unsigned char)*q))
+    q++;
+
+  *p = '\0';
+
+  /* Return pointer to the next word or NUL */
+  return q;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key)
+{
+  char *s1, *s2, *s3, *s4;
+
+  s1 = line;
+  s2 = CPS_SplitWord(s1);
+  s3 = CPS_SplitWord(s2);
+  s4 = CPS_SplitWord(s3);
+
+  /* Require two or three words */
+  if (!*s2 || *s4)
+    return 0;
+
+  if (sscanf(s1, "%"SCNu32, id) != 1)
+    return 0;
+
+  if (*s3) {
+    *type = s2;
+    *key = s3;
+  } else {
+    *type = "MD5";
+    *key = s2;
+  }
+
+  return 1;
+}
diff --git a/cmdparse.h b/cmdparse.h
new file mode 100644
index 0000000..fd1eb43
--- /dev/null
+++ b/cmdparse.h
@@ -0,0 +1,57 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the command parser
+  */
+
+#ifndef GOT_CMDPARSE_H
+#define GOT_CMDPARSE_H
+
+#include "srcparams.h"
+#include "addressing.h"
+
+typedef struct {
+  char *name;
+  int port;
+  SourceParameters params;
+} CPS_NTP_Source;
+
+/* Parse a command to add an NTP server or peer */
+extern int CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src);
+  
+/* Parse a command to allow/deny access */
+extern int CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits);
+
+/* Parse a command to enable local reference */
+extern int CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance);
+
+/* Remove extra white-space and comments */
+extern void CPS_NormalizeLine(char *line);
+
+/* Terminate first word and return pointer to the next word */
+extern char *CPS_SplitWord(char *line);
+
+/* Parse a key from keyfile */
+extern int CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key);
+
+#endif /* GOT_CMDPARSE_H */
diff --git a/conf.c b/conf.c
new file mode 100644
index 0000000..8dd2743
--- /dev/null
+++ b/conf.c
@@ -0,0 +1,2607 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2017, 2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module that reads and processes the configuration file.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "conf.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "nts_ke.h"
+#include "refclock.h"
+#include "cmdmon.h"
+#include "socket.h"
+#include "srcparams.h"
+#include "logging.h"
+#include "nameserv.h"
+#include "memory.h"
+#include "cmdparse.h"
+#include "util.h"
+
+/* ================================================== */
+
+#define MAX_LINE_LENGTH 2048
+#define MAX_CONF_DIRS 10
+#define MAX_INCLUDE_LEVEL 10
+
+/* ================================================== */
+/* Forward prototypes */
+
+static int parse_string(char *line, char **result);
+static int parse_int(char *line, int *result);
+static int parse_double(char *line, double *result);
+static int parse_null(char *line);
+
+static void parse_allow_deny(char *line, ARR_Instance restrictions, int allow);
+static void parse_authselectmode(char *);
+static void parse_bindacqaddress(char *);
+static void parse_bindaddress(char *);
+static void parse_bindcmdaddress(char *);
+static void parse_broadcast(char *);
+static void parse_clientloglimit(char *);
+static void parse_confdir(char *);
+static void parse_fallbackdrift(char *);
+static void parse_hwtimestamp(char *);
+static void parse_include(char *);
+static void parse_initstepslew(char *);
+static void parse_leapsecmode(char *);
+static void parse_local(char *);
+static void parse_log(char *);
+static void parse_mailonchange(char *);
+static void parse_makestep(char *);
+static void parse_maxchange(char *);
+static void parse_ntsserver(char *, ARR_Instance files);
+static void parse_ntstrustedcerts(char *);
+static void parse_ratelimit(char *line, int *enabled, int *interval,
+                            int *burst, int *leak);
+static void parse_refclock(char *);
+static void parse_smoothtime(char *);
+static void parse_source(char *line, char *type, int fatal);
+static void parse_sourcedir(char *);
+static void parse_tempcomp(char *);
+
+/* ================================================== */
+/* Configuration variables */
+
+static int print_config = 0;
+static int restarted = 0;
+static char *rtc_device;
+static int acquisition_port = -1;
+static int ntp_port = NTP_PORT;
+static char *keys_file = NULL;
+static char *drift_file = NULL;
+static char *rtc_file = NULL;
+static double max_update_skew = 1000.0;
+static double correction_time_ratio = 3.0;
+static double max_clock_error = 1.0; /* in ppm */
+static double max_drift = 500000.0; /* in ppm */
+static double max_slew_rate = 1e6 / 12.0; /* in ppm */
+static double clock_precision = 0.0; /* in seconds */
+
+static SRC_AuthSelectMode authselect_mode = SRC_AUTHSELECT_MIX;
+static double max_distance = 3.0;
+static double max_jitter = 1.0;
+static double reselect_distance = 1e-4;
+static double stratum_weight = 1e-3;
+static double combine_limit = 3.0;
+
+static int cmd_port = DEFAULT_CANDM_PORT;
+
+static int raw_measurements = 0;
+static int do_log_measurements = 0;
+static int do_log_selection = 0;
+static int do_log_statistics = 0;
+static int do_log_tracking = 0;
+static int do_log_rtc = 0;
+static int do_log_refclocks = 0;
+static int do_log_tempcomp = 0;
+static int log_banner = 32;
+static char *logdir = NULL;
+static char *dumpdir = NULL;
+
+static int enable_local=0;
+static int local_stratum;
+static int local_orphan;
+static double local_distance;
+
+/* Threshold (in seconds) - if absolute value of initial error is less
+   than this, slew instead of stepping */
+static double init_slew_threshold;
+/* Array of IPAddr */
+static ARR_Instance init_sources;
+
+static int enable_manual=0;
+
+/* Flag set if the RTC runs UTC (default is it runs local time
+   incl. daylight saving). */
+static int rtc_on_utc = 0;
+
+/* Filename used to read the hwclock(8) LOCAL/UTC setting */
+static char *hwclock_file;
+
+/* Flag set if the RTC should be automatically synchronised by kernel */
+static int rtc_sync = 0;
+
+/* Limit and threshold for clock stepping */
+static int make_step_limit = 0;
+static double make_step_threshold = 0.0;
+
+/* Threshold for automatic RTC trimming */
+static double rtc_autotrim_threshold = 0.0;
+
+/* Minimum number of selectables sources required to update the clock */
+static int min_sources = 1;
+
+/* Number of updates before offset checking, number of ignored updates
+   before exiting and the maximum allowed offset */
+static int max_offset_delay = -1;
+static int max_offset_ignore;
+static double max_offset;
+
+/* Maximum and minimum number of samples per source */
+static int max_samples = 0; /* no limit */
+static int min_samples = 6;
+
+/* Threshold for a time adjustment to be logged to syslog */
+static double log_change_threshold = 1.0;
+
+static char *mail_user_on_change = NULL;
+static double mail_change_threshold = 0.0;
+
+/* Flag indicating that we don't want to log clients, e.g. to save
+   memory */
+static int no_client_log = 0;
+
+/* Limit memory allocated for the clients log */
+static unsigned long client_log_limit = 524288;
+
+/* Minimum and maximum fallback drift intervals */
+static int fb_drift_min = 0;
+static int fb_drift_max = 0;
+
+/* IP addresses for binding the NTP server sockets to.  UNSPEC family means
+   INADDR_ANY will be used */
+static IPAddr bind_address4, bind_address6;
+
+/* IP addresses for binding the NTP client sockets to.  UNSPEC family means
+   INADDR_ANY will be used */
+static IPAddr bind_acq_address4, bind_acq_address6;
+
+/* IP addresses for binding the command socket to.  UNSPEC family means
+   the loopback address will be used */
+static IPAddr bind_cmd_address4, bind_cmd_address6;
+
+/* Interface names to bind the NTP server, NTP client, and command socket */
+static char *bind_ntp_iface = NULL;
+static char *bind_acq_iface = NULL;
+static char *bind_cmd_iface = NULL;
+
+/* Path to the Unix domain command socket. */
+static char *bind_cmd_path = NULL;
+
+/* Differentiated Services Code Point (DSCP) in transmitted NTP packets */
+static int ntp_dscp = 0;
+
+/* Path to Samba (ntp_signd) socket. */
+static char *ntp_signd_socket = NULL;
+
+/* Filename to use for storing pid of running chronyd, to prevent multiple
+ * chronyds being started. */
+static char *pidfile = NULL;
+
+/* Rate limiting parameters */
+static int ntp_ratelimit_enabled = 0;
+static int ntp_ratelimit_interval = 3;
+static int ntp_ratelimit_burst = 8;
+static int ntp_ratelimit_leak = 2;
+static int nts_ratelimit_enabled = 0;
+static int nts_ratelimit_interval = 6;
+static int nts_ratelimit_burst = 8;
+static int nts_ratelimit_leak = 2;
+static int cmd_ratelimit_enabled = 0;
+static int cmd_ratelimit_interval = -4;
+static int cmd_ratelimit_burst = 8;
+static int cmd_ratelimit_leak = 2;
+
+/* Smoothing constants */
+static double smooth_max_freq = 0.0; /* in ppm */
+static double smooth_max_wander = 0.0; /* in ppm/s */
+static int smooth_leap_only = 0;
+
+/* Temperature sensor, update interval and compensation coefficients */
+static char *tempcomp_sensor_file = NULL;
+static char *tempcomp_point_file = NULL;
+static double tempcomp_interval;
+static double tempcomp_T0, tempcomp_k0, tempcomp_k1, tempcomp_k2;
+
+static int sched_priority = 0;
+static int lock_memory = 0;
+
+/* Leap second handling mode */
+static REF_LeapMode leapsec_mode = REF_LeapModeSystem;
+
+/* Name of a system timezone containing leap seconds occuring at midnight */
+static char *leapsec_tz = NULL;
+
+/* Name of the user to which will be dropped root privileges. */
+static char *user;
+
+/* NTS server and client configuration */
+static char *nts_dump_dir = NULL;
+static char *nts_ntp_server = NULL;
+static ARR_Instance nts_server_cert_files; /* array of (char *) */
+static ARR_Instance nts_server_key_files; /* array of (char *) */
+static int nts_server_port = NKE_PORT;
+static int nts_server_processes = 1;
+static int nts_server_connections = 100;
+static int nts_refresh = 2419200; /* 4 weeks */
+static int nts_rotate = 604800; /* 1 week */
+static ARR_Instance nts_trusted_certs_paths; /* array of (char *) */
+static ARR_Instance nts_trusted_certs_ids; /* array of uint32_t */
+
+/* Number of clock updates needed to enable certificate time checks */
+static int no_cert_time_check = 0;
+
+/* Flag disabling use of system trusted certificates */
+static int no_system_cert = 0;
+
+/* Array of CNF_HwTsInterface */
+static ARR_Instance hwts_interfaces;
+
+/* PTP event port (disabled by default) */
+static int ptp_port = 0;
+
+typedef struct {
+  NTP_Source_Type type;
+  int pool;
+  CPS_NTP_Source params;
+} NTP_Source;
+
+/* Array of NTP_Source */
+static ARR_Instance ntp_sources;
+/* Array of (char *) */
+static ARR_Instance ntp_source_dirs;
+/* Array of uint32_t corresponding to ntp_sources (for sourcedirs reload) */
+static ARR_Instance ntp_source_ids;
+
+/* Array of RefclockParameters */
+static ARR_Instance refclock_sources;
+
+typedef struct _AllowDeny {
+  IPAddr ip;
+  int subnet_bits;
+  int all; /* 1 to override existing more specific defns */
+  int allow; /* 0 for deny, 1 for allow */
+} AllowDeny;
+
+/* Arrays of AllowDeny */
+static ARR_Instance ntp_restrictions;
+static ARR_Instance cmd_restrictions;
+
+typedef struct {
+  NTP_Remote_Address addr;
+  int interval;
+} NTP_Broadcast_Destination;
+
+/* Array of NTP_Broadcast_Destination */
+static ARR_Instance broadcasts;
+
+/* ================================================== */
+
+/* The line number in the configuration file being processed */
+static int line_number;
+static const char *processed_file;
+static const char *processed_command;
+
+static int include_level = 0;
+
+/* ================================================== */
+
+static void
+command_parse_error(void)
+{
+    LOG_FATAL("Could not parse %s directive at line %d%s%s",
+        processed_command, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+}
+
+/* ================================================== */
+
+static void
+other_parse_error(const char *message)
+{
+    LOG_FATAL("%s at line %d%s%s",
+        message, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+}
+
+/* ================================================== */
+
+static int
+get_number_of_args(char *line)
+{
+  int num = 0;
+
+  /* The line is normalized, between arguments is just one space */
+  if (*line == ' ')
+    line++;
+  if (*line)
+    num++;
+  for (; *line; line++) {
+    if (*line == ' ')
+      num++;
+  }
+
+  return num;
+}
+
+/* ================================================== */
+
+static void
+check_number_of_args(char *line, int num)
+{
+  num -= get_number_of_args(line);
+
+  if (num) {
+    LOG_FATAL("%s arguments for %s directive at line %d%s%s",
+        num > 0 ? "Missing" : "Too many",
+        processed_command, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+  }
+}
+
+/* ================================================== */
+
+void
+CNF_Initialise(int r, int client_only)
+{
+  restarted = r;
+
+  hwts_interfaces = ARR_CreateInstance(sizeof (CNF_HwTsInterface));
+
+  init_sources = ARR_CreateInstance(sizeof (IPAddr));
+  ntp_sources = ARR_CreateInstance(sizeof (NTP_Source));
+  ntp_source_dirs = ARR_CreateInstance(sizeof (char *));
+  ntp_source_ids = ARR_CreateInstance(sizeof (uint32_t));
+  refclock_sources = ARR_CreateInstance(sizeof (RefclockParameters));
+  broadcasts = ARR_CreateInstance(sizeof (NTP_Broadcast_Destination));
+
+  ntp_restrictions = ARR_CreateInstance(sizeof (AllowDeny));
+  cmd_restrictions = ARR_CreateInstance(sizeof (AllowDeny));
+
+  nts_server_cert_files = ARR_CreateInstance(sizeof (char *));
+  nts_server_key_files = ARR_CreateInstance(sizeof (char *));
+  nts_trusted_certs_paths = ARR_CreateInstance(sizeof (char *));
+  nts_trusted_certs_ids = ARR_CreateInstance(sizeof (uint32_t));
+
+  rtc_device = Strdup(DEFAULT_RTC_DEVICE);
+  hwclock_file = Strdup(DEFAULT_HWCLOCK_FILE);
+  user = Strdup(DEFAULT_USER);
+
+  if (client_only) {
+    cmd_port = ntp_port = 0;
+  } else {
+    bind_cmd_path = Strdup(DEFAULT_COMMAND_SOCKET);
+    pidfile = Strdup(DEFAULT_PID_FILE);
+  }
+
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &bind_address4);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET6, &bind_address6);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &bind_acq_address4);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET6, &bind_acq_address6);
+  SCK_GetLoopbackIPAddress(IPADDR_INET4, &bind_cmd_address4);
+  SCK_GetLoopbackIPAddress(IPADDR_INET6, &bind_cmd_address6);
+}
+
+/* ================================================== */
+
+void
+CNF_Finalise(void)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(hwts_interfaces); i++)
+    Free(((CNF_HwTsInterface *)ARR_GetElement(hwts_interfaces, i))->name);
+  ARR_DestroyInstance(hwts_interfaces);
+
+  for (i = 0; i < ARR_GetSize(ntp_sources); i++)
+    Free(((NTP_Source *)ARR_GetElement(ntp_sources, i))->params.name);
+  for (i = 0; i < ARR_GetSize(ntp_source_dirs); i++)
+    Free(*(char **)ARR_GetElement(ntp_source_dirs, i));
+  for (i = 0; i < ARR_GetSize(refclock_sources); i++) {
+    Free(((RefclockParameters *)ARR_GetElement(refclock_sources, i))->driver_name);
+    Free(((RefclockParameters *)ARR_GetElement(refclock_sources, i))->driver_parameter);
+  }
+  for (i = 0; i < ARR_GetSize(nts_server_cert_files); i++)
+    Free(*(char **)ARR_GetElement(nts_server_cert_files, i));
+  for (i = 0; i < ARR_GetSize(nts_server_key_files); i++)
+    Free(*(char **)ARR_GetElement(nts_server_key_files, i));
+  for (i = 0; i < ARR_GetSize(nts_trusted_certs_paths); i++)
+    Free(*(char **)ARR_GetElement(nts_trusted_certs_paths, i));
+
+  ARR_DestroyInstance(init_sources);
+  ARR_DestroyInstance(ntp_sources);
+  ARR_DestroyInstance(ntp_source_dirs);
+  ARR_DestroyInstance(ntp_source_ids);
+  ARR_DestroyInstance(refclock_sources);
+  ARR_DestroyInstance(broadcasts);
+
+  ARR_DestroyInstance(ntp_restrictions);
+  ARR_DestroyInstance(cmd_restrictions);
+
+  ARR_DestroyInstance(nts_server_cert_files);
+  ARR_DestroyInstance(nts_server_key_files);
+  ARR_DestroyInstance(nts_trusted_certs_paths);
+  ARR_DestroyInstance(nts_trusted_certs_ids);
+
+  Free(drift_file);
+  Free(dumpdir);
+  Free(hwclock_file);
+  Free(keys_file);
+  Free(leapsec_tz);
+  Free(logdir);
+  Free(bind_ntp_iface);
+  Free(bind_acq_iface);
+  Free(bind_cmd_iface);
+  Free(bind_cmd_path);
+  Free(ntp_signd_socket);
+  Free(pidfile);
+  Free(rtc_device);
+  Free(rtc_file);
+  Free(user);
+  Free(mail_user_on_change);
+  Free(tempcomp_sensor_file);
+  Free(tempcomp_point_file);
+  Free(nts_dump_dir);
+  Free(nts_ntp_server);
+}
+
+/* ================================================== */
+
+void
+CNF_EnablePrint(void)
+{
+  print_config = 1;
+}
+
+/* ================================================== */
+
+/* Read the configuration file */
+void
+CNF_ReadFile(const char *filename)
+{
+  FILE *in;
+  char line[MAX_LINE_LENGTH + 1];
+  int i;
+
+  include_level++;
+  if (include_level > MAX_INCLUDE_LEVEL)
+    LOG_FATAL("Maximum include level reached");
+
+  in = UTI_OpenFile(NULL, filename, NULL, 'R', 0);
+
+  for (i = 1; fgets(line, sizeof(line), in); i++) {
+    CNF_ParseLine(filename, i, line);
+  }
+
+  fclose(in);
+
+  include_level--;
+}
+
+/* ================================================== */
+
+/* Parse one configuration line */
+void
+CNF_ParseLine(const char *filename, int number, char *line)
+{
+  char *p, *command;
+
+  /* Set global variables used in error messages */
+  processed_file = filename;
+  line_number = number;
+
+  /* Detect truncated line */
+  if (strlen(line) >= MAX_LINE_LENGTH)
+    other_parse_error("String too long");
+
+  /* Remove extra white-space and comments */
+  CPS_NormalizeLine(line);
+
+  /* Skip blank lines */
+  if (!*line) {
+    processed_file = NULL;
+    return;
+  }
+
+  /* We have a real line, now try to match commands */
+  processed_command = command = line;
+  p = CPS_SplitWord(line);
+
+  if (print_config && strcasecmp(command, "include") && strcasecmp(command, "confdir"))
+    printf("%s%s%s\n", command, p[0] != '\0' ? " " : "", p);
+
+  if (!strcasecmp(command, "acquisitionport")) {
+    parse_int(p, &acquisition_port);
+  } else if (!strcasecmp(command, "allow")) {
+    parse_allow_deny(p, ntp_restrictions, 1);
+  } else if (!strcasecmp(command, "authselectmode")) {
+    parse_authselectmode(p);
+  } else if (!strcasecmp(command, "bindacqaddress")) {
+    parse_bindacqaddress(p);
+  } else if (!strcasecmp(command, "bindacqdevice")) {
+    parse_string(p, &bind_acq_iface);
+  } else if (!strcasecmp(command, "bindaddress")) {
+    parse_bindaddress(p);
+  } else if (!strcasecmp(command, "bindcmdaddress")) {
+    parse_bindcmdaddress(p);
+  } else if (!strcasecmp(command, "bindcmddevice")) {
+    parse_string(p, &bind_cmd_iface);
+  } else if (!strcasecmp(command, "binddevice")) {
+    parse_string(p, &bind_ntp_iface);
+  } else if (!strcasecmp(command, "broadcast")) {
+    parse_broadcast(p);
+  } else if (!strcasecmp(command, "clientloglimit")) {
+    parse_clientloglimit(p);
+  } else if (!strcasecmp(command, "clockprecision")) {
+    parse_double(p, &clock_precision);
+  } else if (!strcasecmp(command, "cmdallow")) {
+    parse_allow_deny(p, cmd_restrictions, 1);
+  } else if (!strcasecmp(command, "cmddeny")) {
+    parse_allow_deny(p, cmd_restrictions, 0);
+  } else if (!strcasecmp(command, "cmdport")) {
+    parse_int(p, &cmd_port);
+  } else if (!strcasecmp(command, "cmdratelimit")) {
+    parse_ratelimit(p, &cmd_ratelimit_enabled, &cmd_ratelimit_interval,
+                    &cmd_ratelimit_burst, &cmd_ratelimit_leak);
+  } else if (!strcasecmp(command, "combinelimit")) {
+    parse_double(p, &combine_limit);
+  } else if (!strcasecmp(command, "confdir")) {
+    parse_confdir(p);
+  } else if (!strcasecmp(command, "corrtimeratio")) {
+    parse_double(p, &correction_time_ratio);
+  } else if (!strcasecmp(command, "deny")) {
+    parse_allow_deny(p, ntp_restrictions, 0);
+  } else if (!strcasecmp(command, "driftfile")) {
+    parse_string(p, &drift_file);
+  } else if (!strcasecmp(command, "dscp")) {
+    parse_int(p, &ntp_dscp);
+  } else if (!strcasecmp(command, "dumpdir")) {
+    parse_string(p, &dumpdir);
+  } else if (!strcasecmp(command, "dumponexit")) {
+    /* Silently ignored */
+  } else if (!strcasecmp(command, "fallbackdrift")) {
+    parse_fallbackdrift(p);
+  } else if (!strcasecmp(command, "hwclockfile")) {
+    parse_string(p, &hwclock_file);
+  } else if (!strcasecmp(command, "hwtimestamp")) {
+    parse_hwtimestamp(p);
+  } else if (!strcasecmp(command, "include")) {
+    parse_include(p);
+  } else if (!strcasecmp(command, "initstepslew")) {
+    parse_initstepslew(p);
+  } else if (!strcasecmp(command, "keyfile")) {
+    parse_string(p, &keys_file);
+  } else if (!strcasecmp(command, "leapsecmode")) {
+    parse_leapsecmode(p);
+  } else if (!strcasecmp(command, "leapsectz")) {
+    parse_string(p, &leapsec_tz);
+  } else if (!strcasecmp(command, "local")) {
+    parse_local(p);
+  } else if (!strcasecmp(command, "lock_all")) {
+    lock_memory = parse_null(p);
+  } else if (!strcasecmp(command, "log")) {
+    parse_log(p);
+  } else if (!strcasecmp(command, "logbanner")) {
+    parse_int(p, &log_banner);
+  } else if (!strcasecmp(command, "logchange")) {
+    parse_double(p, &log_change_threshold);
+  } else if (!strcasecmp(command, "logdir")) {
+    parse_string(p, &logdir);
+  } else if (!strcasecmp(command, "mailonchange")) {
+    parse_mailonchange(p);
+  } else if (!strcasecmp(command, "makestep")) {
+    parse_makestep(p);
+  } else if (!strcasecmp(command, "manual")) {
+    enable_manual = parse_null(p);
+  } else if (!strcasecmp(command, "maxchange")) {
+    parse_maxchange(p);
+  } else if (!strcasecmp(command, "maxclockerror")) {
+    parse_double(p, &max_clock_error);
+  } else if (!strcasecmp(command, "maxdistance")) {
+    parse_double(p, &max_distance);
+  } else if (!strcasecmp(command, "maxdrift")) {
+    parse_double(p, &max_drift);
+  } else if (!strcasecmp(command, "maxjitter")) {
+    parse_double(p, &max_jitter);
+  } else if (!strcasecmp(command, "maxntsconnections")) {
+    parse_int(p, &nts_server_connections);
+  } else if (!strcasecmp(command, "maxsamples")) {
+    parse_int(p, &max_samples);
+  } else if (!strcasecmp(command, "maxslewrate")) {
+    parse_double(p, &max_slew_rate);
+  } else if (!strcasecmp(command, "maxupdateskew")) {
+    parse_double(p, &max_update_skew);
+  } else if (!strcasecmp(command, "minsamples")) {
+    parse_int(p, &min_samples);
+  } else if (!strcasecmp(command, "minsources")) {
+    parse_int(p, &min_sources);
+  } else if (!strcasecmp(command, "nocerttimecheck")) {
+    parse_int(p, &no_cert_time_check);
+  } else if (!strcasecmp(command, "noclientlog")) {
+    no_client_log = parse_null(p);
+  } else if (!strcasecmp(command, "nosystemcert")) {
+    no_system_cert = parse_null(p);
+  } else if (!strcasecmp(command, "ntpsigndsocket")) {
+    parse_string(p, &ntp_signd_socket);
+  } else if (!strcasecmp(command, "ntsratelimit")) {
+    parse_ratelimit(p, &nts_ratelimit_enabled, &nts_ratelimit_interval,
+                    &nts_ratelimit_burst, &nts_ratelimit_leak);
+  } else if (!strcasecmp(command, "ntscachedir") ||
+             !strcasecmp(command, "ntsdumpdir")) {
+    parse_string(p, &nts_dump_dir);
+  } else if (!strcasecmp(command, "ntsntpserver")) {
+    parse_string(p, &nts_ntp_server);
+  } else if (!strcasecmp(command, "ntsport")) {
+    parse_int(p, &nts_server_port);
+  } else if (!strcasecmp(command, "ntsprocesses")) {
+    parse_int(p, &nts_server_processes);
+  } else if (!strcasecmp(command, "ntsrefresh")) {
+    parse_int(p, &nts_refresh);
+  } else if (!strcasecmp(command, "ntsrotate")) {
+    parse_int(p, &nts_rotate);
+  } else if (!strcasecmp(command, "ntsservercert")) {
+    parse_ntsserver(p, nts_server_cert_files);
+  } else if (!strcasecmp(command, "ntsserverkey")) {
+    parse_ntsserver(p, nts_server_key_files);
+  } else if (!strcasecmp(command, "ntstrustedcerts")) {
+    parse_ntstrustedcerts(p);
+  } else if (!strcasecmp(command, "peer")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "pidfile")) {
+    parse_string(p, &pidfile);
+  } else if (!strcasecmp(command, "pool")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "port")) {
+    parse_int(p, &ntp_port);
+  } else if (!strcasecmp(command, "ptpport")) {
+    parse_int(p, &ptp_port);
+  } else if (!strcasecmp(command, "ratelimit")) {
+    parse_ratelimit(p, &ntp_ratelimit_enabled, &ntp_ratelimit_interval,
+                    &ntp_ratelimit_burst, &ntp_ratelimit_leak);
+  } else if (!strcasecmp(command, "refclock")) {
+    parse_refclock(p);
+  } else if (!strcasecmp(command, "reselectdist")) {
+    parse_double(p, &reselect_distance);
+  } else if (!strcasecmp(command, "rtcautotrim")) {
+    parse_double(p, &rtc_autotrim_threshold);
+  } else if (!strcasecmp(command, "rtcdevice")) {
+    parse_string(p, &rtc_device);
+  } else if (!strcasecmp(command, "rtcfile")) {
+    parse_string(p, &rtc_file);
+  } else if (!strcasecmp(command, "rtconutc")) {
+    rtc_on_utc = parse_null(p);
+  } else if (!strcasecmp(command, "rtcsync")) {
+    rtc_sync = parse_null(p);
+  } else if (!strcasecmp(command, "sched_priority")) {
+    parse_int(p, &sched_priority);
+  } else if (!strcasecmp(command, "server")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "smoothtime")) {
+    parse_smoothtime(p);
+  } else if (!strcasecmp(command, "sourcedir")) {
+    parse_sourcedir(p);
+  } else if (!strcasecmp(command, "stratumweight")) {
+    parse_double(p, &stratum_weight);
+  } else if (!strcasecmp(command, "tempcomp")) {
+    parse_tempcomp(p);
+  } else if (!strcasecmp(command, "user")) {
+    parse_string(p, &user);
+  } else if (!strcasecmp(command, "commandkey") ||
+             !strcasecmp(command, "generatecommandkey") ||
+             !strcasecmp(command, "linux_freq_scale") ||
+             !strcasecmp(command, "linux_hz")) {
+    LOG(LOGS_WARN, "%s directive is no longer supported", command);
+  } else {
+    other_parse_error("Invalid directive");
+  }
+
+  processed_file = processed_command = NULL;
+}
+
+/* ================================================== */
+
+static int
+parse_string(char *line, char **result)
+{
+  check_number_of_args(line, 1);
+  Free(*result);
+  *result = Strdup(line);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_int(char *line, int *result)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%d", result) != 1) {
+    command_parse_error();
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_double(char *line, double *result)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%lf", result) != 1) {
+    command_parse_error();
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_null(char *line)
+{
+  check_number_of_args(line, 0);
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+parse_source(char *line, char *type, int fatal)
+{
+  NTP_Source source;
+
+  if (strcasecmp(type, "peer") == 0) {
+    source.type = NTP_PEER;
+    source.pool = 0;
+  } else if (strcasecmp(type, "pool") == 0) {
+    source.type = NTP_SERVER;
+    source.pool = 1;
+  } else if (strcasecmp(type, "server") == 0) {
+    source.type = NTP_SERVER;
+    source.pool = 0;
+  } else {
+    if (fatal)
+      command_parse_error();
+    return;
+  }
+
+  /* Avoid comparing uninitialized data in compare_sources() */
+  memset(&source.params, 0, sizeof (source.params));
+
+  if (!CPS_ParseNTPSourceAdd(line, &source.params)) {
+    if (fatal)
+      command_parse_error();
+    return;
+  }
+
+  source.params.name = Strdup(source.params.name);
+  ARR_AppendElement(ntp_sources, &source);
+}
+
+/* ================================================== */
+
+static void
+parse_sourcedir(char *line)
+{
+  char *s;
+
+  s = Strdup(line);
+  ARR_AppendElement(ntp_source_dirs, &s);
+}
+
+/* ================================================== */
+
+static void
+parse_ratelimit(char *line, int *enabled, int *interval, int *burst, int *leak)
+{
+  int n, val;
+  char *opt;
+
+  *enabled = 1;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (sscanf(line, "%d%n", &val, &n) != 1) {
+      command_parse_error();
+      return;
+    }
+    line += n;
+    if (!strcasecmp(opt, "interval"))
+      *interval = val;
+    else if (!strcasecmp(opt, "burst"))
+      *burst = val;
+    else if (!strcasecmp(opt, "leak"))
+      *leak = val;
+    else
+      command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_refclock(char *line)
+{
+  int n, poll, dpoll, filter_length, pps_rate, min_samples, max_samples, sel_options;
+  int local, max_lock_age, pps_forced, stratum, tai;
+  uint32_t ref_id, lock_ref_id;
+  double offset, delay, precision, max_dispersion, pulse_width;
+  char *p, *cmd, *name, *param;
+  unsigned char ref[5];
+  RefclockParameters *refclock;
+
+  poll = 4;
+  dpoll = 0;
+  filter_length = 64;
+  local = 0;
+  pps_forced = 0;
+  pps_rate = 0;
+  min_samples = SRC_DEFAULT_MINSAMPLES;
+  max_samples = SRC_DEFAULT_MAXSAMPLES;
+  sel_options = 0;
+  offset = 0.0;
+  delay = 1e-9;
+  precision = 0.0;
+  max_dispersion = 0.0;
+  pulse_width = 0.0;
+  ref_id = 0;
+  max_lock_age = 2;
+  lock_ref_id = 0;
+  stratum = 0;
+  tai = 0;
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  name = Strdup(p);
+
+  p = line;
+  line = CPS_SplitWord(line);
+  param = Strdup(p);
+
+  for (cmd = line; *cmd; line += n, cmd = line) {
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(cmd, "refid")) {
+      if (sscanf(line, "%4s%n", (char *)ref, &n) != 1)
+        break;
+      ref_id = (uint32_t)ref[0] << 24 | ref[1] << 16 | ref[2] << 8 | ref[3];
+    } else if (!strcasecmp(cmd, "lock")) {
+      if (sscanf(line, "%4s%n", (char *)ref, &n) != 1)
+        break;
+      lock_ref_id = (uint32_t)ref[0] << 24 | ref[1] << 16 | ref[2] << 8 | ref[3];
+    } else if (!strcasecmp(cmd, "poll")) {
+      if (sscanf(line, "%d%n", &poll, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "dpoll")) {
+      if (sscanf(line, "%d%n", &dpoll, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "filter")) {
+      if (sscanf(line, "%d%n", &filter_length, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "local")) {
+      n = 0;
+      local = 1;
+    } else if (!strcasecmp(cmd, "rate")) {
+      if (sscanf(line, "%d%n", &pps_rate, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "minsamples")) {
+      if (sscanf(line, "%d%n", &min_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxlockage")) {
+      if (sscanf(line, "%d%n", &max_lock_age, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxsamples")) {
+      if (sscanf(line, "%d%n", &max_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "offset")) {
+      if (sscanf(line, "%lf%n", &offset, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "delay")) {
+      if (sscanf(line, "%lf%n", &delay, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "pps")) {
+      n = 0;
+      pps_forced = 1;
+    } else if (!strcasecmp(cmd, "precision")) {
+      if (sscanf(line, "%lf%n", &precision, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxdispersion")) {
+      if (sscanf(line, "%lf%n", &max_dispersion, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "stratum")) {
+      if (sscanf(line, "%d%n", &stratum, &n) != 1 ||
+          stratum >= NTP_MAX_STRATUM || stratum < 0)
+        break;
+    } else if (!strcasecmp(cmd, "tai")) {
+      n = 0;
+      tai = 1;
+    } else if (!strcasecmp(cmd, "width")) {
+      if (sscanf(line, "%lf%n", &pulse_width, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "noselect")) {
+      n = 0;
+      sel_options |= SRC_SELECT_NOSELECT;
+    } else if (!strcasecmp(cmd, "prefer")) {
+      n = 0;
+      sel_options |= SRC_SELECT_PREFER;
+    } else if (!strcasecmp(cmd, "trust")) {
+      n = 0;
+      sel_options |= SRC_SELECT_TRUST;
+    } else if (!strcasecmp(cmd, "require")) {
+      n = 0;
+      sel_options |= SRC_SELECT_REQUIRE;
+    } else {
+      other_parse_error("Invalid refclock option");
+      return;
+    }
+  }
+
+  if (*cmd) {
+    command_parse_error();
+    return;
+  }
+
+  refclock = (RefclockParameters *)ARR_GetNewElement(refclock_sources);
+  refclock->driver_name = name;
+  refclock->driver_parameter = param;
+  refclock->driver_poll = dpoll;
+  refclock->poll = poll;
+  refclock->filter_length = filter_length;
+  refclock->local = local;
+  refclock->pps_forced = pps_forced;
+  refclock->pps_rate = pps_rate;
+  refclock->min_samples = min_samples;
+  refclock->max_samples = max_samples;
+  refclock->sel_options = sel_options;
+  refclock->stratum = stratum;
+  refclock->tai = tai;
+  refclock->offset = offset;
+  refclock->delay = delay;
+  refclock->precision = precision;
+  refclock->max_dispersion = max_dispersion;
+  refclock->pulse_width = pulse_width;
+  refclock->ref_id = ref_id;
+  refclock->max_lock_age = max_lock_age;
+  refclock->lock_ref_id = lock_ref_id;
+}
+
+/* ================================================== */
+
+static void
+parse_log(char *line)
+{
+  char *log_name;
+  do {
+    log_name = line;
+    line = CPS_SplitWord(line);
+    if (*log_name) {
+      if (!strcmp(log_name, "rawmeasurements")) {
+        do_log_measurements = 1;
+        raw_measurements = 1;
+      } else if (!strcmp(log_name, "measurements")) {
+        do_log_measurements = 1;
+      } else if (!strcmp(log_name, "selection")) {
+        do_log_selection = 1;
+      } else if (!strcmp(log_name, "statistics")) {
+        do_log_statistics = 1;
+      } else if (!strcmp(log_name, "tracking")) {
+        do_log_tracking = 1;
+      } else if (!strcmp(log_name, "rtc")) {
+        do_log_rtc = 1;
+      } else if (!strcmp(log_name, "refclocks")) {
+        do_log_refclocks = 1;
+      } else if (!strcmp(log_name, "tempcomp")) {
+        do_log_tempcomp = 1;
+      } else {
+        other_parse_error("Invalid log parameter");
+        break;
+      }
+    } else {
+      break;
+    }
+  } while (1);
+}
+
+/* ================================================== */
+
+static void
+parse_local(char *line)
+{
+  if (!CPS_ParseLocal(line, &local_stratum, &local_orphan, &local_distance))
+    command_parse_error();
+  enable_local = 1;
+}
+
+/* ================================================== */
+
+static void
+parse_initstepslew(char *line)
+{
+  char *p, *hostname;
+  IPAddr ip_addr;
+
+  /* Ignore the line if chronyd was started with -R. */
+  if (restarted) {
+    return;
+  }
+
+  ARR_SetSize(init_sources, 0);
+  p = CPS_SplitWord(line);
+
+  if (sscanf(line, "%lf", &init_slew_threshold) != 1) {
+    command_parse_error();
+    return;
+  }
+
+  while (*p) {
+    hostname = p;
+    p = CPS_SplitWord(p);
+    if (*hostname) {
+      if (DNS_Name2IPAddress(hostname, &ip_addr, 1) == DNS_Success) {
+        ARR_AppendElement(init_sources, &ip_addr);
+      } else {
+        LOG(LOGS_WARN, "Could not resolve address of initstepslew server %s", hostname);
+      }
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_leapsecmode(char *line)
+{
+  if (!strcasecmp(line, "system"))
+    leapsec_mode = REF_LeapModeSystem;
+  else if (!strcasecmp(line, "slew"))
+    leapsec_mode = REF_LeapModeSlew;
+  else if (!strcasecmp(line, "step"))
+    leapsec_mode = REF_LeapModeStep;
+  else if (!strcasecmp(line, "ignore"))
+    leapsec_mode = REF_LeapModeIgnore;
+  else
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_clientloglimit(char *line)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%lu", &client_log_limit) != 1) {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_fallbackdrift(char *line)
+{
+  check_number_of_args(line, 2);
+  if (sscanf(line, "%d %d", &fb_drift_min, &fb_drift_max) != 2) {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_makestep(char *line)
+{
+  check_number_of_args(line, 2);
+  if (sscanf(line, "%lf %d", &make_step_threshold, &make_step_limit) != 2) {
+    make_step_limit = 0;
+    command_parse_error();
+  }
+
+  /* Disable limited makestep if chronyd was started with -R. */
+  if (restarted && make_step_limit > 0) {
+    make_step_limit = 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_maxchange(char *line)
+{
+  check_number_of_args(line, 3);
+  if (sscanf(line, "%lf %d %d", &max_offset, &max_offset_delay, &max_offset_ignore) != 3) {
+    max_offset_delay = -1;
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_mailonchange(char *line)
+{
+  char *address;
+  check_number_of_args(line, 2);
+  address = line;
+  line = CPS_SplitWord(line);
+  Free(mail_user_on_change);
+  if (sscanf(line, "%lf", &mail_change_threshold) == 1) {
+    mail_user_on_change = Strdup(address);
+  } else {
+    mail_user_on_change = NULL;
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_ntsserver(char *line, ARR_Instance files)
+{
+  char *file = NULL;
+
+  parse_string(line, &file);
+  ARR_AppendElement(files, &file);
+}
+
+/* ================================================== */
+
+static void
+parse_ntstrustedcerts(char *line)
+{
+  uint32_t id;
+  char *path;
+
+  if (get_number_of_args(line) == 2) {
+    path = CPS_SplitWord(line);
+    if (sscanf(line, "%"SCNu32, &id) != 1)
+      command_parse_error();
+  } else {
+    check_number_of_args(line, 1);
+    path = line;
+    id = 0;
+  }
+
+  path = Strdup(path);
+
+  ARR_AppendElement(nts_trusted_certs_paths, &path);
+  ARR_AppendElement(nts_trusted_certs_ids, &id);
+}
+
+/* ================================================== */
+
+static void
+parse_allow_deny(char *line, ARR_Instance restrictions, int allow)
+{
+  int all, subnet_bits;
+  AllowDeny *node;
+  IPAddr ip;
+
+  if (!CPS_ParseAllowDeny(line, &all, &ip, &subnet_bits))
+    command_parse_error();
+
+  node = ARR_GetNewElement(restrictions);
+  node->allow = allow;
+  node->all = all;
+  node->ip = ip;
+  node->subnet_bits = subnet_bits;
+}
+  
+/* ================================================== */
+
+static void
+parse_authselectmode(char *line)
+{
+  if (!strcasecmp(line, "require"))
+    authselect_mode = SRC_AUTHSELECT_REQUIRE;
+  else if (!strcasecmp(line, "prefer"))
+    authselect_mode = SRC_AUTHSELECT_PREFER;
+  else if (!strcasecmp(line, "mix"))
+    authselect_mode = SRC_AUTHSELECT_MIX;
+  else if (!strcasecmp(line, "ignore"))
+    authselect_mode = SRC_AUTHSELECT_IGNORE;
+  else
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_bindacqaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+  if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_acq_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_acq_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_bindaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+  if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_bindcmdaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+
+  /* Address starting with / is for the Unix domain socket */
+  if (line[0] == '/') {
+    parse_string(line, &bind_cmd_path);
+    /* / disables the socket */
+    if (strcmp(bind_cmd_path, "/") == 0) {
+      Free(bind_cmd_path);
+      bind_cmd_path = NULL;
+    }
+  } else if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_cmd_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_cmd_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_broadcast(char *line)
+{
+  /* Syntax : broadcast <interval> <broadcast-IP-addr> [<port>] */
+  NTP_Broadcast_Destination *destination;
+  int port;
+  int interval;
+  char *p;
+  IPAddr ip;
+  
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(p, "%d", &interval) != 1) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!UTI_StringToIP(p, &ip)) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (*p) {
+    if (sscanf(p, "%d", &port) != 1 || *line) {
+      command_parse_error();
+      return;
+    }
+  } else {
+    /* default port */
+    port = NTP_PORT;
+  }
+
+  destination = (NTP_Broadcast_Destination *)ARR_GetNewElement(broadcasts);
+  destination->addr.ip_addr = ip;
+  destination->addr.port = port;
+  destination->interval = interval;
+}
+
+/* ================================================== */
+
+static void
+parse_smoothtime(char *line)
+{
+  if (get_number_of_args(line) != 3)
+    check_number_of_args(line, 2);
+
+  if (sscanf(line, "%lf %lf", &smooth_max_freq, &smooth_max_wander) != 2) {
+    smooth_max_freq = 0.0;
+    command_parse_error();
+  }
+
+  line = CPS_SplitWord(CPS_SplitWord(line));
+  smooth_leap_only = 0;
+
+  if (*line) {
+    if (!strcasecmp(line, "leaponly"))
+      smooth_leap_only = 1;
+    else
+      command_parse_error();
+  }
+}
+
+/* ================================================== */
+static void
+parse_tempcomp(char *line)
+{
+  char *p;
+  int point_form;
+
+  point_form = get_number_of_args(line) == 3;
+
+  if (!point_form)
+    check_number_of_args(line, 6);
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!*p) {
+    command_parse_error();
+    return;
+  }
+
+  Free(tempcomp_point_file);
+
+  if (point_form) {
+    if (sscanf(line, "%lf", &tempcomp_interval) != 1) {
+      command_parse_error();
+      return;
+    }
+    tempcomp_point_file = Strdup(CPS_SplitWord(line));
+  } else {
+    if (sscanf(line, "%lf %lf %lf %lf %lf", &tempcomp_interval,
+               &tempcomp_T0, &tempcomp_k0, &tempcomp_k1, &tempcomp_k2) != 5) {
+      command_parse_error();
+      return;
+    }
+    tempcomp_point_file = NULL;
+  }
+
+  Free(tempcomp_sensor_file);
+  tempcomp_sensor_file = Strdup(p);
+}
+
+/* ================================================== */
+
+static void
+parse_hwtimestamp(char *line)
+{
+  CNF_HwTsInterface *iface;
+  char *p, filter[5];
+  int n;
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  iface = ARR_GetNewElement(hwts_interfaces);
+  iface->name = Strdup(p);
+  iface->minpoll = 0;
+  iface->min_samples = 2;
+  iface->max_samples = 16;
+  iface->nocrossts = 0;
+  iface->rxfilter = CNF_HWTS_RXFILTER_ANY;
+  iface->precision = 100.0e-9;
+  iface->tx_comp = 0.0;
+  iface->rx_comp = 0.0;
+
+  for (p = line; *p; line += n, p = line) {
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(p, "maxsamples")) {
+      if (sscanf(line, "%d%n", &iface->max_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "minpoll")) {
+      if (sscanf(line, "%d%n", &iface->minpoll, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "minsamples")) {
+      if (sscanf(line, "%d%n", &iface->min_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "precision")) {
+      if (sscanf(line, "%lf%n", &iface->precision, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "rxcomp")) {
+      if (sscanf(line, "%lf%n", &iface->rx_comp, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "txcomp")) {
+      if (sscanf(line, "%lf%n", &iface->tx_comp, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "rxfilter")) {
+      if (sscanf(line, "%4s%n", filter, &n) != 1)
+        break;
+      if (!strcasecmp(filter, "none"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_NONE;
+      else if (!strcasecmp(filter, "ntp"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_NTP;
+      else if (!strcasecmp(filter, "ptp"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_PTP;
+      else if (!strcasecmp(filter, "all"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_ALL;
+      else
+        break;
+    } else if (!strcasecmp(p, "nocrossts")) {
+      n = 0;
+      iface->nocrossts = 1;
+    } else {
+      break;
+    }
+  }
+
+  if (*p)
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static const char *
+get_basename(const char *path)
+{
+  const char *b = strrchr(path, '/');
+  return b ? b + 1 : path;
+}
+
+/* ================================================== */
+
+static int
+compare_basenames(const void *a, const void *b)
+{
+  return strcmp(get_basename(*(const char * const *)a),
+                get_basename(*(const char * const *)b));
+}
+
+/* ================================================== */
+
+static int
+search_dirs(char *line, const char *suffix, void (*file_handler)(const char *path))
+{
+  char *dirs[MAX_CONF_DIRS], buf[MAX_LINE_LENGTH], *path;
+  size_t i, j, k, locations, n_dirs;
+  glob_t gl;
+
+  n_dirs = UTI_SplitString(line, dirs, MAX_CONF_DIRS);
+  if (n_dirs < 1 || n_dirs > MAX_CONF_DIRS)
+    return 0;
+
+  /* Get the paths of all config files in the specified directories */
+  for (i = 0; i < n_dirs; i++) {
+    if (snprintf(buf, sizeof (buf), "%s/*%s", dirs[i], suffix) >= sizeof (buf))
+      assert(0);
+    if (glob(buf, GLOB_NOSORT | (i > 0 ? GLOB_APPEND : 0), NULL, &gl) != 0)
+      ;
+  }
+
+  if (gl.gl_pathc > 0) {
+    /* Sort the paths by filenames */
+    qsort(gl.gl_pathv, gl.gl_pathc, sizeof (gl.gl_pathv[0]), compare_basenames);
+
+    for (i = 0; i < gl.gl_pathc; i += locations) {
+      /* Count directories containing files with this name */
+      for (j = i + 1, locations = 1; j < gl.gl_pathc; j++, locations++) {
+        if (compare_basenames(&gl.gl_pathv[i], &gl.gl_pathv[j]) != 0)
+          break;
+      }
+
+      /* Read the first file of this name in the order of the directive */
+      for (j = 0; j < n_dirs; j++) {
+        for (k = 0; k < locations; k++) {
+          path = gl.gl_pathv[i + k];
+          if (strncmp(path, dirs[j], strlen(dirs[j])) == 0 &&
+              strlen(dirs[j]) + 1 + strlen(get_basename(path)) == strlen(path)) {
+            file_handler(path);
+            break;
+          }
+        }
+        if (k < locations)
+          break;
+      }
+    }
+  }
+
+  globfree(&gl);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+parse_confdir(char *line)
+{
+  if (!search_dirs(line, ".conf", CNF_ReadFile))
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_include(char *line)
+{
+  glob_t gl;
+  size_t i;
+  int r;
+
+  check_number_of_args(line, 1);
+
+  if ((r = glob(line,
+#ifdef GLOB_NOMAGIC
+                GLOB_NOMAGIC |
+#endif
+                GLOB_ERR, NULL, &gl)) != 0) {
+    if (r != GLOB_NOMATCH)
+      LOG_FATAL("Could not search for files matching %s", line);
+
+    DEBUG_LOG("glob of %s failed", line);
+    return;
+  }
+
+  for (i = 0; i < gl.gl_pathc; i++)
+    CNF_ReadFile(gl.gl_pathv[i]);
+
+  globfree(&gl);
+}
+
+/* ================================================== */
+
+static void
+load_source_file(const char *filename)
+{
+  char line[MAX_LINE_LENGTH + 1];
+  FILE *f;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'r', 0);
+  if (!f)
+    return;
+
+  while (fgets(line, sizeof (line), f)) {
+    /* Require lines to be terminated */
+    if (line[0] == '\0' || line[strlen(line) - 1] != '\n')
+      break;
+
+    CPS_NormalizeLine(line);
+    if (line[0] == '\0')
+      continue;
+
+    parse_source(CPS_SplitWord(line), line, 0);
+  }
+
+  fclose(f);
+}
+
+/* ================================================== */
+
+static int
+compare_sources(const void *a, const void *b)
+{
+  const NTP_Source *sa = a, *sb = b;
+  int d;
+
+  if (!sa->params.name)
+    return -1;
+  if (!sb->params.name)
+    return 1;
+  if ((d = strcmp(sa->params.name, sb->params.name)) != 0)
+    return d;
+  if ((d = (int)(sa->type) - (int)(sb->type)) != 0)
+    return d;
+  if ((d = sa->pool - sb->pool) != 0)
+    return d;
+  if ((d = sa->params.port - sb->params.port) != 0)
+    return d;
+  return memcmp(&sa->params.params, &sb->params.params, sizeof (sa->params.params));
+}
+
+/* ================================================== */
+
+static void
+reload_source_dirs(void)
+{
+  NTP_Source *prev_sources, *new_sources, *source;
+  unsigned int i, j, prev_size, new_size, unresolved;
+  uint32_t *prev_ids, *new_ids;
+  char buf[MAX_LINE_LENGTH];
+  NSR_Status s;
+  int d;
+
+  prev_size = ARR_GetSize(ntp_source_ids);
+  if (prev_size > 0 && ARR_GetSize(ntp_sources) != prev_size)
+    assert(0);
+
+  /* Save the current sources and their configuration IDs */
+  prev_ids = MallocArray(uint32_t, prev_size);
+  memcpy(prev_ids, ARR_GetElements(ntp_source_ids), prev_size * sizeof (prev_ids[0]));
+  prev_sources = MallocArray(NTP_Source, prev_size);
+  memcpy(prev_sources, ARR_GetElements(ntp_sources), prev_size * sizeof (prev_sources[0]));
+
+  /* Load the sources again */
+  ARR_SetSize(ntp_sources, 0);
+  for (i = 0; i < ARR_GetSize(ntp_source_dirs); i++) {
+    if (snprintf(buf, sizeof (buf), "%s",
+                 *(char **)ARR_GetElement(ntp_source_dirs, i)) >= sizeof (buf))
+      assert(0);
+    search_dirs(buf, ".sources", load_source_file);
+  }
+
+  /* Add new and remove existing sources according to the new configuration.
+     Avoid removing and adding the same source again to keep its state. */
+
+  new_size = ARR_GetSize(ntp_sources);
+  new_sources = ARR_GetElements(ntp_sources);
+  ARR_SetSize(ntp_source_ids, new_size);
+  new_ids = ARR_GetElements(ntp_source_ids);
+  unresolved = 0;
+
+  qsort(new_sources, new_size, sizeof (new_sources[0]), compare_sources);
+
+  for (i = j = 0; i < prev_size || j < new_size; ) {
+    if (i < prev_size && j < new_size)
+      d = compare_sources(&prev_sources[i], &new_sources[j]);
+    else
+      d = i < prev_size ? -1 : 1;
+
+    if (d < 0) {
+      /* Remove the missing source */
+      if (prev_sources[i].params.name[0] != '\0')
+        NSR_RemoveSourcesById(prev_ids[i]);
+      i++;
+    } else if (d > 0) {
+      /* Add a newly configured source */
+      source = &new_sources[j];
+      s = NSR_AddSourceByName(source->params.name, source->params.port, source->pool,
+                              source->type, &source->params.params, &new_ids[j]);
+
+      if (s == NSR_UnresolvedName) {
+        unresolved++;
+      } else if (s != NSR_Success) {
+        LOG(LOGS_ERR, "Could not add source %s", source->params.name);
+
+        /* Mark the source as not present */
+        source->params.name[0] = '\0';
+      }
+      j++;
+    } else {
+      /* Keep the existing source */
+      new_ids[j] = prev_ids[i];
+      i++, j++;
+    }
+  }
+
+  for (i = 0; i < prev_size; i++)
+    Free(prev_sources[i].params.name);
+  Free(prev_sources);
+  Free(prev_ids);
+
+  if (unresolved > 0)
+    NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+void
+CNF_CreateDirs(uid_t uid, gid_t gid)
+{
+  char *dir;
+
+  /* Create a directory for the Unix domain command socket */
+  if (bind_cmd_path) {
+    dir = UTI_PathToDir(bind_cmd_path);
+    UTI_CreateDirAndParents(dir, 0770, uid, gid);
+
+    /* Check the permissions and owner/group in case the directory already
+       existed.  It MUST NOT be accessible by others as permissions on Unix
+       domain sockets are ignored on some systems (e.g. Solaris). */
+    if (!UTI_CheckDirPermissions(dir, 0770, uid, gid)) {
+      LOG(LOGS_WARN, "Disabled command socket %s", bind_cmd_path);
+      Free(bind_cmd_path);
+      bind_cmd_path = NULL;
+    }
+
+    Free(dir);
+  }
+
+  if (logdir)
+    UTI_CreateDirAndParents(logdir, 0750, uid, gid);
+  if (dumpdir)
+    UTI_CreateDirAndParents(dumpdir, 0750, uid, gid);
+  if (nts_dump_dir)
+    UTI_CreateDirAndParents(nts_dump_dir, 0750, uid, gid);
+}
+
+/* ================================================== */
+
+void
+CNF_AddInitSources(void)
+{
+  CPS_NTP_Source cps_source;
+  NTP_Remote_Address ntp_addr;
+  char dummy_hostname[2] = "H";
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(init_sources); i++) {
+    /* Get the default NTP params */
+    CPS_ParseNTPSourceAdd(dummy_hostname, &cps_source);
+
+    /* Add the address as a server specified with the iburst option */
+    ntp_addr.ip_addr = *(IPAddr *)ARR_GetElement(init_sources, i);
+    ntp_addr.port = cps_source.port;
+    cps_source.params.iburst = 1;
+
+    if (NSR_AddSource(&ntp_addr, NTP_SERVER, &cps_source.params, NULL) != NSR_Success)
+      LOG(LOGS_ERR, "Could not add source %s", UTI_IPToString(&ntp_addr.ip_addr));
+  }
+
+  ARR_SetSize(init_sources, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_AddSources(void)
+{
+  NTP_Source *source;
+  unsigned int i;
+  NSR_Status s;
+
+  for (i = 0; i < ARR_GetSize(ntp_sources); i++) {
+    source = (NTP_Source *)ARR_GetElement(ntp_sources, i);
+
+    s = NSR_AddSourceByName(source->params.name, source->params.port, source->pool,
+                            source->type, &source->params.params, NULL);
+    if (s != NSR_Success && s != NSR_UnresolvedName)
+      LOG(LOGS_ERR, "Could not add source %s", source->params.name);
+
+    Free(source->params.name);
+  }
+
+  ARR_SetSize(ntp_sources, 0);
+
+  reload_source_dirs();
+}
+
+/* ================================================== */
+
+void
+CNF_AddRefclocks(void)
+{
+  RefclockParameters *refclock;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclock_sources); i++) {
+    refclock = ARR_GetElement(refclock_sources, i);
+    RCL_AddRefclock(refclock);
+    Free(refclock->driver_name);
+    Free(refclock->driver_parameter);
+  }
+
+  ARR_SetSize(refclock_sources, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_AddBroadcasts(void)
+{
+  unsigned int i;
+  NTP_Broadcast_Destination *destination;
+
+  for (i = 0; i < ARR_GetSize(broadcasts); i++) {
+    destination = (NTP_Broadcast_Destination *)ARR_GetElement(broadcasts, i);
+    NCR_AddBroadcastDestination(&destination->addr, destination->interval);
+  }
+
+  ARR_SetSize(broadcasts, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_ReloadSources(void)
+{
+  reload_source_dirs();
+}
+
+/* ================================================== */
+
+int
+CNF_GetNTPPort(void)
+{
+  return ntp_port;
+}
+
+/* ================================================== */
+
+int
+CNF_GetAcquisitionPort(void)
+{
+  return acquisition_port;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetDriftFile(void)
+{
+  return drift_file;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogBanner(void)
+{
+  return log_banner;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetLogDir(void)
+{
+  return logdir;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetDumpDir(void)
+{
+  return dumpdir;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogMeasurements(int *raw)
+{
+  *raw = raw_measurements;
+  return do_log_measurements;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogSelection(void)
+{
+  return do_log_selection;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogStatistics(void)
+{
+  return do_log_statistics;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogTracking(void)
+{
+  return do_log_tracking;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogRtc(void)
+{
+  return do_log_rtc;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogRefclocks(void)
+{
+  return do_log_refclocks;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogTempComp(void)
+{
+  return do_log_tempcomp;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetKeysFile(void)
+{
+  return keys_file;
+}
+
+/* ================================================== */
+
+double
+CNF_GetRtcAutotrim(void)
+{
+  return rtc_autotrim_threshold;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetRtcFile(void)
+{
+  return rtc_file;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetRtcDevice(void)
+{
+  return rtc_device;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxUpdateSkew(void)
+{
+  return max_update_skew;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxDrift(void)
+{
+  return max_drift;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxClockError(void)
+{
+  return max_clock_error;
+}
+
+/* ================================================== */
+
+double
+CNF_GetCorrectionTimeRatio(void)
+{
+  return correction_time_ratio;
+}
+
+/* ================================================== */
+
+SRC_AuthSelectMode
+CNF_GetAuthSelectMode(void)
+{
+  return authselect_mode;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxSlewRate(void)
+{
+  return max_slew_rate;
+}
+
+/* ================================================== */
+
+double
+CNF_GetClockPrecision(void)
+{
+  return clock_precision;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxDistance(void)
+{
+  return max_distance;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxJitter(void)
+{
+  return max_jitter;
+}
+
+/* ================================================== */
+
+double
+CNF_GetReselectDistance(void)
+{
+  return reselect_distance;
+}
+
+/* ================================================== */
+
+double
+CNF_GetStratumWeight(void)
+{
+  return stratum_weight;
+}
+
+/* ================================================== */
+
+double
+CNF_GetCombineLimit(void)
+{
+  return combine_limit;
+}
+
+/* ================================================== */
+
+int
+CNF_GetManualEnabled(void)
+{
+  return enable_manual;
+}
+
+/* ================================================== */
+
+int
+CNF_GetCommandPort(void) {
+  return cmd_port;
+}
+
+/* ================================================== */
+
+int
+CNF_AllowLocalReference(int *stratum, int *orphan, double *distance)
+{
+  if (enable_local) {
+    *stratum = local_stratum;
+    *orphan = local_orphan;
+    *distance = local_distance;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+CNF_GetRtcOnUtc(void)
+{
+  return rtc_on_utc;
+}
+
+/* ================================================== */
+
+int
+CNF_GetRtcSync(void)
+{
+  return rtc_sync;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMakeStep(int *limit, double *threshold)
+{
+  *limit = make_step_limit;
+  *threshold = make_step_threshold;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMaxChange(int *delay, int *ignore, double *offset)
+{
+  *delay = max_offset_delay;
+  *ignore = max_offset_ignore;
+  *offset = max_offset;
+}
+
+/* ================================================== */
+
+double
+CNF_GetLogChange(void)
+{
+  return log_change_threshold;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMailOnChange(int *enabled, double *threshold, char **user)
+{
+  if (mail_user_on_change) {
+    *enabled = 1;
+    *threshold = mail_change_threshold;
+    *user = mail_user_on_change;
+  } else {
+    *enabled = 0;
+    *threshold = 0.0;
+    *user = NULL;
+  }
+}  
+
+/* ================================================== */
+
+void
+CNF_SetupAccessRestrictions(void)
+{
+  AllowDeny *node;
+  int status;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(ntp_restrictions); i++) {
+    node = ARR_GetElement(ntp_restrictions, i);
+    status = NCR_AddAccessRestriction(&node->ip, node->subnet_bits, node->allow, node->all);
+    if (!status) {
+      LOG_FATAL("Bad subnet in %s/%d", UTI_IPToString(&node->ip), node->subnet_bits);
+    }
+  }
+
+  for (i = 0; i < ARR_GetSize(cmd_restrictions); i++) {
+    node = ARR_GetElement(cmd_restrictions, i);
+    status = CAM_AddAccessRestriction(&node->ip, node->subnet_bits, node->allow, node->all);
+    if (!status) {
+      LOG_FATAL("Bad subnet in %s/%d", UTI_IPToString(&node->ip), node->subnet_bits);
+    }
+  }
+
+  ARR_SetSize(ntp_restrictions, 0);
+  ARR_SetSize(cmd_restrictions, 0);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoClientLog(void)
+{
+  return no_client_log;
+}
+
+/* ================================================== */
+
+unsigned long
+CNF_GetClientLogLimit(void)
+{
+  return client_log_limit;
+}
+
+/* ================================================== */
+
+void
+CNF_GetFallbackDrifts(int *min, int *max)
+{
+  *min = fb_drift_min;
+  *max = fb_drift_max;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindAcquisitionAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_acq_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_acq_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindNtpInterface(void)
+{
+  return bind_ntp_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindAcquisitionInterface(void)
+{
+  return bind_acq_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindCommandInterface(void)
+{
+  return bind_cmd_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindCommandPath(void)
+{
+  return bind_cmd_path;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindCommandAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_cmd_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_cmd_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtpDscp(void)
+{
+  return ntp_dscp;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtpSigndSocket(void)
+{
+  return ntp_signd_socket;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetPidFile(void)
+{
+  return pidfile;
+}
+
+/* ================================================== */
+
+REF_LeapMode
+CNF_GetLeapSecMode(void)
+{
+  return leapsec_mode;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetLeapSecTimezone(void)
+{
+  return leapsec_tz;
+}
+
+/* ================================================== */
+
+int
+CNF_GetSchedPriority(void)
+{
+  return sched_priority;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLockMemory(void)
+{
+  return lock_memory;
+}
+
+/* ================================================== */
+
+int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = ntp_ratelimit_interval;
+  *burst = ntp_ratelimit_burst;
+  *leak = ntp_ratelimit_leak;
+  return ntp_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+int CNF_GetNtsRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = nts_ratelimit_interval;
+  *burst = nts_ratelimit_burst;
+  *leak = nts_ratelimit_leak;
+  return nts_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = cmd_ratelimit_interval;
+  *burst = cmd_ratelimit_burst;
+  *leak = cmd_ratelimit_leak;
+  return cmd_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+void
+CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only)
+{
+  *max_freq = smooth_max_freq;
+  *max_wander = smooth_max_wander;
+  *leap_only = smooth_leap_only;
+}
+
+/* ================================================== */
+
+void
+CNF_GetTempComp(char **file, double *interval, char **point_file, double *T0, double *k0, double *k1, double *k2)
+{
+  *file = tempcomp_sensor_file;
+  *point_file = tempcomp_point_file;
+  *interval = tempcomp_interval;
+  *T0 = tempcomp_T0;
+  *k0 = tempcomp_k0;
+  *k1 = tempcomp_k1;
+  *k2 = tempcomp_k2;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetUser(void)
+{
+  return user;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMaxSamples(void)
+{
+  return max_samples;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMinSamples(void)
+{
+  return min_samples;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMinSources(void)
+{
+  return min_sources;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetHwclockFile(void)
+{
+  return hwclock_file;
+}
+
+/* ================================================== */
+
+int
+CNF_GetInitSources(void)
+{
+  return ARR_GetSize(init_sources);
+}
+
+/* ================================================== */
+
+double
+CNF_GetInitStepThreshold(void)
+{
+  return init_slew_threshold;
+}
+
+/* ================================================== */
+
+int
+CNF_GetHwTsInterface(unsigned int index, CNF_HwTsInterface **iface)
+{
+  if (index >= ARR_GetSize(hwts_interfaces))
+    return 0;
+
+  *iface = (CNF_HwTsInterface *)ARR_GetElement(hwts_interfaces, index);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+CNF_GetPtpPort(void)
+{
+  return ptp_port;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtsDumpDir(void)
+{
+  return nts_dump_dir;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtsNtpServer(void)
+{
+  return nts_ntp_server;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerCertAndKeyFiles(const char ***certs, const char ***keys)
+{
+  *certs = ARR_GetElements(nts_server_cert_files);
+  *keys = ARR_GetElements(nts_server_key_files);
+
+  if (ARR_GetSize(nts_server_cert_files) != ARR_GetSize(nts_server_key_files))
+    LOG_FATAL("Uneven number of NTS certs and keys");
+
+  return ARR_GetSize(nts_server_cert_files);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerPort(void)
+{
+  return nts_server_port;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerProcesses(void)
+{
+  return nts_server_processes;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerConnections(void)
+{
+  return nts_server_connections;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsRefresh(void)
+{
+  return nts_refresh;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsRotate(void)
+{
+  return nts_rotate;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsTrustedCertsPaths(const char ***paths, uint32_t **ids)
+{
+  *paths = ARR_GetElements(nts_trusted_certs_paths);
+  *ids = ARR_GetElements(nts_trusted_certs_ids);
+
+  if (ARR_GetSize(nts_trusted_certs_paths) != ARR_GetSize(nts_trusted_certs_ids))
+    assert(0);
+
+  return ARR_GetSize(nts_trusted_certs_paths);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoSystemCert(void)
+{
+  return no_system_cert;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoCertTimeCheck(void)
+{
+  return no_cert_time_check;
+}
diff --git a/conf.h b/conf.h
new file mode 100644
index 0000000..11fd11d
--- /dev/null
+++ b/conf.h
@@ -0,0 +1,170 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2013-2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for configuration module
+  */
+
+#ifndef GOT_CONF_H
+#define GOT_CONF_H
+
+#include "addressing.h"
+#include "reference.h"
+#include "sources.h"
+
+extern void CNF_Initialise(int restarted, int client_only);
+extern void CNF_Finalise(void);
+
+extern void CNF_EnablePrint(void);
+
+extern char *CNF_GetRtcDevice(void);
+
+extern void CNF_ReadFile(const char *filename);
+extern void CNF_ParseLine(const char *filename, int number, char *line);
+
+extern void CNF_CreateDirs(uid_t uid, gid_t gid);
+
+extern void CNF_AddInitSources(void);
+extern void CNF_AddSources(void);
+extern void CNF_AddBroadcasts(void);
+extern void CNF_AddRefclocks(void);
+
+extern void CNF_ReloadSources(void);
+
+extern int CNF_GetAcquisitionPort(void);
+extern int CNF_GetNTPPort(void);
+extern char *CNF_GetDriftFile(void);
+extern char *CNF_GetLogDir(void);
+extern char *CNF_GetDumpDir(void);
+extern int CNF_GetLogBanner(void);
+extern int CNF_GetLogMeasurements(int *raw);
+extern int CNF_GetLogSelection(void);
+extern int CNF_GetLogStatistics(void);
+extern int CNF_GetLogTracking(void);
+extern int CNF_GetLogRtc(void);
+extern int CNF_GetLogRefclocks(void);
+extern int CNF_GetLogTempComp(void);
+extern char *CNF_GetKeysFile(void);
+extern char *CNF_GetRtcFile(void);
+extern int CNF_GetManualEnabled(void);
+extern int CNF_GetCommandPort(void);
+extern int CNF_GetRtcOnUtc(void);
+extern int CNF_GetRtcSync(void);
+extern void CNF_GetMakeStep(int *limit, double *threshold);
+extern void CNF_GetMaxChange(int *delay, int *ignore, double *offset);
+extern double CNF_GetLogChange(void);
+extern void CNF_GetMailOnChange(int *enabled, double *threshold, char **user);
+extern int CNF_GetNoClientLog(void);
+extern unsigned long CNF_GetClientLogLimit(void);
+extern void CNF_GetFallbackDrifts(int *min, int *max);
+extern void CNF_GetBindAddress(int family, IPAddr *addr);
+extern void CNF_GetBindAcquisitionAddress(int family, IPAddr *addr);
+extern void CNF_GetBindCommandAddress(int family, IPAddr *addr);
+extern char *CNF_GetBindNtpInterface(void);
+extern char *CNF_GetBindAcquisitionInterface(void);
+extern char *CNF_GetBindCommandInterface(void);
+extern char *CNF_GetBindCommandPath(void);
+extern int CNF_GetNtpDscp(void);
+extern char *CNF_GetNtpSigndSocket(void);
+extern char *CNF_GetPidFile(void);
+extern REF_LeapMode CNF_GetLeapSecMode(void);
+extern char *CNF_GetLeapSecTimezone(void);
+
+/* Value returned in ppm, as read from file */
+extern double CNF_GetMaxUpdateSkew(void);
+extern double CNF_GetMaxClockError(void);
+extern double CNF_GetMaxDrift(void);
+extern double CNF_GetCorrectionTimeRatio(void);
+extern double CNF_GetMaxSlewRate(void);
+extern double CNF_GetClockPrecision(void);
+
+extern SRC_AuthSelectMode CNF_GetAuthSelectMode(void);
+extern double CNF_GetMaxDistance(void);
+extern double CNF_GetMaxJitter(void);
+extern double CNF_GetReselectDistance(void);
+extern double CNF_GetStratumWeight(void);
+extern double CNF_GetCombineLimit(void);
+
+extern int CNF_AllowLocalReference(int *stratum, int *orphan, double *distance);
+
+extern void CNF_SetupAccessRestrictions(void);
+
+extern int CNF_GetSchedPriority(void);
+extern int CNF_GetLockMemory(void);
+
+extern int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak);
+extern int CNF_GetNtsRateLimit(int *interval, int *burst, int *leak);
+extern int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak);
+extern void CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only);
+extern void CNF_GetTempComp(char **file, double *interval, char **point_file, double *T0, double *k0, double *k1, double *k2);
+
+extern char *CNF_GetUser(void);
+
+extern int CNF_GetMaxSamples(void);
+extern int CNF_GetMinSamples(void);
+
+extern int CNF_GetMinSources(void);
+
+extern double CNF_GetRtcAutotrim(void);
+extern char *CNF_GetHwclockFile(void);
+
+extern int CNF_GetInitSources(void);
+extern double CNF_GetInitStepThreshold(void);
+
+typedef enum {
+  CNF_HWTS_RXFILTER_ANY,
+  CNF_HWTS_RXFILTER_NONE,
+  CNF_HWTS_RXFILTER_NTP,
+  CNF_HWTS_RXFILTER_PTP,
+  CNF_HWTS_RXFILTER_ALL,
+} CNF_HwTs_RxFilter;
+
+typedef struct {
+  char *name;
+  int minpoll;
+  int min_samples;
+  int max_samples;
+  int nocrossts;
+  CNF_HwTs_RxFilter rxfilter;
+  double precision;
+  double tx_comp;
+  double rx_comp;
+} CNF_HwTsInterface;
+
+extern int CNF_GetHwTsInterface(unsigned int index, CNF_HwTsInterface **iface);
+
+extern int CNF_GetPtpPort(void);
+
+extern char *CNF_GetNtsDumpDir(void);
+extern char *CNF_GetNtsNtpServer(void);
+extern int CNF_GetNtsServerCertAndKeyFiles(const char ***certs, const char ***keys);
+extern int CNF_GetNtsServerPort(void);
+extern int CNF_GetNtsServerProcesses(void);
+extern int CNF_GetNtsServerConnections(void);
+extern int CNF_GetNtsRefresh(void);
+extern int CNF_GetNtsRotate(void);
+extern int CNF_GetNtsTrustedCertsPaths(const char ***paths, uint32_t **ids);
+extern int CNF_GetNoSystemCert(void);
+extern int CNF_GetNoCertTimeCheck(void);
+
+#endif /* GOT_CONF_H */
diff --git a/configure b/configure
new file mode 100755
index 0000000..fd777c8
--- /dev/null
+++ b/configure
@@ -0,0 +1,1134 @@
+#!/bin/sh
+# =======================================================================
+#
+# chronyd/chronyc - Programs for keeping computer clocks accurate.
+#
+# Copyright (C) Richard P. Curnow  1997-2003
+# Copyright (C) Bryan Christianson  2016
+# Copyright (C) Miroslav Lichvar  2009, 2012-2021
+# Copyright (C) Stefan R. Filipek  2019
+#
+# =======================================================================
+
+# This configure script determines the operating system type and version
+
+# ======================================================================
+# FUNCTIONS
+
+#{{{ test_code
+test_code () {
+  name=$1
+  headers=$2
+  cflags=$3
+  ldflags=$4
+  code=$5
+
+  printf "%s" "Checking for $name : "
+
+  (
+    echo "#include \"config.h\""
+    for h in $headers; do
+      echo "#include <$h>"
+    done
+    echo "int main(int argc, char **argv) {"
+    echo "$code"
+    echo "return 0; }"
+  ) > conftest.c
+
+  echo "conftest.c:" >> config.log
+  cat conftest.c >> config.log
+  echo $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
+    $MYLDFLAGS >> config.log
+  $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
+    $MYLDFLAGS >> config.log 2>&1
+
+  if [ $? -eq 0 ]
+  then
+    echo "Yes"
+    result=0
+  else
+    echo "No"
+    result=1
+  fi
+  rm -f conftest.c conftest
+  echo >> config.log
+  return $result
+}
+#}}}
+#{{{ test_executable
+test_executable () {
+  name=$1
+  executable=$2
+  options=$3
+
+  printf "%s" "Checking for $name : "
+
+  echo $executable $options >> config.log
+  $executable $options >> config.log 2>&1
+
+  if [ $? -eq 0 ]
+  then
+    echo "Yes"
+    result=0
+  else
+    echo "No"
+    result=1
+  fi
+  echo >> config.log
+  return $result
+}
+#}}}
+#{{{ pkg_config
+pkg_config () {
+  $PKG_CONFIG "$@" 2>> config.log
+}
+#}}}
+#{{{ usage
+usage () {
+  cat <<EOF
+\`configure' configures this package to adapt to many kinds of systems.
+
+Usage: ./configure [OPTION]...
+
+Defaults for the options are specified in brackets.
+
+Configuration:
+  -h, --help              display this help and exit
+
+Installation directories:
+  --prefix=PREFIX         install architecture-independent files in PREFIX
+                          [/usr/local]
+  --exec-prefix=EPREFIX   install architecture-dependent files in EPREFIX
+                          [PREFIX]
+
+By default, \`make install' will install all the files in
+\`/usr/local/bin', \`/usr/local/lib' etc.  You can specify
+an installation prefix other than \`/usr/local' using \`--prefix',
+for instance \`--prefix=$HOME'.
+
+For better control, use the options below.
+  --disable-readline     Disable line editing support
+  --without-editline     Don't use editline even if it is available
+  --disable-sechash      Disable support for hashes other than MD5
+  --without-nettle       Don't use nettle even if it is available
+  --without-nss          Don't use NSS even if it is available
+  --without-tomcrypt     Don't use libtomcrypt even if it is available
+  --disable-nts          Disable NTS support
+  --without-gnutls       Don't use gnutls even if it is available
+  --disable-cmdmon       Disable command and monitoring support
+  --disable-ntp          Disable NTP support
+  --disable-refclock     Disable reference clock support
+  --disable-phc          Disable PHC refclock driver
+  --disable-pps          Disable PPS refclock driver
+  --disable-ipv6         Disable IPv6 support
+  --disable-rtc          Don't include RTC even on Linux
+  --disable-privdrop     Disable support for dropping root privileges
+  --without-libcap       Don't use libcap even if it is available
+  --enable-scfilter      Enable support for system call filtering
+  --without-seccomp      Don't use seccomp even if it is available
+  --disable-asyncdns     Disable asynchronous name resolving
+  --disable-forcednsretry Don't retry on permanent DNS error
+  --without-clock-gettime Don't use clock_gettime() even if it is available
+  --disable-timestamping Disable support for SW/HW timestamping
+  --enable-ntp-signd     Enable support for MS-SNTP authentication in Samba
+  --with-ntp-era=SECONDS Specify earliest assumed NTP time in seconds
+                         since 1970-01-01 [50*365 days ago]
+  --with-user=USER       Specify default chronyd user [root]
+  --with-hwclockfile=PATH Specify default path to hwclock(8) adjtime file
+  --with-pidfile=PATH    Specify default pidfile [/var/run/chrony/chronyd.pid]
+  --with-rtcdevice=PATH  Specify default path to RTC device [/dev/rtc]
+  --with-sendmail=PATH   Path to sendmail binary [/usr/lib/sendmail]
+  --enable-debug         Enable debugging support
+
+Fine tuning of the installation directories:
+  --sysconfdir=DIR       chrony.conf location [/etc]
+  --bindir=DIR           user executables [EPREFIX/bin]
+  --sbindir=DIR          system admin executables [EPREFIX/sbin]
+  --datarootdir=DIR      data root [PREFIX/share]
+  --mandir=DIR           man documentation [DATAROOTDIR/man]
+  --docdir=DIR           documentation root [DATAROOTDIR/doc/chrony]
+  --localstatedir=DIR    modifiable single-machine data [/var]
+  --chronyrundir=DIR     location for chrony sockets [LOCALSTATEDIR/run/chrony]
+  --chronyvardir=DIR     location for chrony data [LOCALSTATEDIR/lib/chrony]
+
+Overriding system detection when cross-compiling:
+  --host-system=OS       Specify system name (uname -s)
+  --host-release=REL     Specify system release (uname -r)
+  --host-machine=CPU     Specify machine (uname -m)
+
+Some influential environment variables:
+  CC          C compiler command
+  CFLAGS      C compiler flags
+  CPPFLAGS    C preprocessor flags, e.g. -I<include dir> if you have
+              headers in a nonstandard directory <include dir>
+  LDFLAGS     linker flags, e.g. -L<lib dir> if you have libraries in a
+              nonstandard directory <lib dir>
+  PKG_CONFIG  path to pkg-config utility
+  PKG_CONFIG_PATH
+              directories to add to pkg-config's search path
+  PKG_CONFIG_LIBDIR
+              path overriding pkg-config's built-in search path
+
+Use these variables to override the choices made by \`configure' or to help
+it to find libraries and programs with nonstandard names/locations.
+
+EOF
+
+}
+#}}}
+#{{{
+add_def () {
+  if [ "x$2" = "x" ]; then
+    echo "#define $1 1" >> config.h
+  else
+    echo "#define $1 $2" >> config.h
+  fi
+}
+#}}}
+#{{{ get_features
+get_features () {
+  ff=1
+  for f; do
+    if [ "$ff" = "0" ]; then
+      printf " "
+    fi
+    if grep "define FEAT_$f" config.h > /dev/null; then
+      printf "%s" "+$f"
+    else
+      printf "%s" "-$f"
+    fi
+    ff=0
+  done
+}
+#}}}
+
+# ======================================================================
+
+
+
+OPERATINGSYSTEM=`uname -s`
+VERSION=`uname -r`
+MACHINE=`uname -m`
+
+LIBS=""
+EXTRA_LIBS=""
+EXTRA_CLI_LIBS=""
+EXTRA_OBJECTS=""
+EXTRA_CLI_OBJECTS=""
+
+feat_debug=0
+feat_cmdmon=1
+feat_ntp=1
+feat_refclock=1
+feat_readline=1
+try_editline=1
+feat_sechash=1
+try_nettle=1
+try_nss=1
+try_tomcrypt=1
+feat_nts=1
+try_gnutls=1
+feat_rtc=1
+try_rtc=0
+feat_droproot=1
+try_libcap=-1
+try_clockctl=0
+feat_scfilter=0
+try_seccomp=-1
+priv_ops=""
+feat_ipv6=1
+feat_phc=1
+try_phc=0
+feat_pps=1
+try_setsched=0
+try_lockmem=0
+feat_asyncdns=1
+feat_forcednsretry=1
+try_clock_gettime=1
+try_arc4random=1
+try_recvmmsg=1
+feat_timestamping=1
+try_timestamping=0
+feat_ntp_signd=0
+ntp_era_split=""
+use_pthread=0
+default_user="root"
+default_hwclockfile=""
+default_pidfile="/var/run/chrony/chronyd.pid"
+default_rtcdevice="/dev/rtc"
+mail_program="/usr/lib/sendmail"
+
+for option
+do
+    case "$option" in
+    --enable-debug )
+      feat_debug=1
+    ;;
+    --disable-readline )
+      feat_readline=0
+    ;;
+    --without-editline )
+      try_editline=0
+    ;;
+    --prefix=* | --install_prefix=* )
+      SETPREFIX=`echo $option | sed -e 's/[^=]*=//;'`
+    ;;
+    --exec-prefix=* )
+      SETEPREFIX=`echo $option | sed -e 's/[^=]*=//;'`
+    ;;
+    --sysconfdir=* )
+      SETSYSCONFDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --bindir=* )
+      SETBINDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --sbindir=* )
+      SETSBINDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --datarootdir=* )
+      SETDATAROOTDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --mandir=* )
+      SETMANDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --docdir=* )
+      SETDOCDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --localstatedir=* )
+      SETLOCALSTATEDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --chronyrundir=* | --chronysockdir=* )
+      SETCHRONYRUNDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --chronyvardir=* )
+      SETCHRONYVARDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --disable-cmdmon)
+      feat_cmdmon=0
+    ;;
+    --disable-ntp)
+      feat_ntp=0
+    ;;
+    --disable-refclock)
+      feat_refclock=0
+    ;;
+    --disable-rtc)
+      feat_rtc=0
+    ;;
+    --disable-ipv6)
+      feat_ipv6=0
+    ;;
+    --disable-phc)
+      feat_phc=0
+    ;;
+    --disable-pps)
+      feat_pps=0
+    ;;
+    --disable-privdrop)
+      feat_droproot=0
+    ;;
+    --without-libcap|--disable-linuxcaps)
+      try_libcap=0
+    ;;
+    --enable-scfilter)
+      feat_scfilter=1
+    ;;
+    --disable-scfilter)
+      feat_scfilter=0
+    ;;
+    --without-seccomp)
+      try_seccomp=0
+    ;;
+    --disable-asyncdns)
+      feat_asyncdns=0
+    ;;
+    --disable-forcednsretry)
+      feat_forcednsretry=0
+    ;;
+    --without-clock-gettime)
+      try_clock_gettime=0
+    ;;
+    --disable-timestamping)
+      feat_timestamping=0
+    ;;
+    --enable-ntp-signd)
+      feat_ntp_signd=1
+    ;;
+    --with-ntp-era=* )
+      ntp_era_split=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-user=* )
+      default_user=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-hwclockfile=* )
+      default_hwclockfile=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-pidfile=* )
+      default_pidfile=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-rtcdevice=* )
+      default_rtcdevice=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-sendmail=* )
+      mail_program=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --disable-sechash )
+      feat_sechash=0
+    ;;
+    --without-nettle )
+      try_nettle=0
+    ;;
+    --without-nss )
+      try_nss=0
+    ;;
+    --without-tomcrypt )
+      try_tomcrypt=0
+    ;;
+    --disable-nts )
+      feat_nts=0
+    ;;
+    --without-gnutls )
+      try_gnutls=0
+    ;;
+    --host-system=* )
+      OPERATINGSYSTEM=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --host-release=* )
+      VERSION=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --host-machine=* )
+      MACHINE=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --help | -h )
+      usage
+      exit 0
+    ;;
+    * )
+    echo "Unrecognized option : " $option
+    esac
+done
+
+rm -f config.h config.log
+
+SYSTEM=${OPERATINGSYSTEM}-${MACHINE}
+
+case $OPERATINGSYSTEM in
+    Linux)
+        EXTRA_OBJECTS="sys_generic.o sys_linux.o sys_timex.o sys_posix.o"
+        [ $try_libcap != "0" ] && try_libcap=1
+        try_rtc=1
+        [ $try_seccomp != "0" ] && try_seccomp=1
+        try_timestamping=1
+        try_setsched=1
+        try_lockmem=1
+        try_phc=1
+        try_arc4random=0
+        add_def LINUX
+        echo "Configuring for " $SYSTEM
+    ;;
+    FreeBSD)
+        # recvmmsg() seems to be broken on FreeBSD 11.0 and it's just
+        # a wrapper around recvmsg()
+        try_recvmmsg=0
+        EXTRA_OBJECTS="sys_generic.o sys_netbsd.o sys_timex.o sys_posix.o"
+        try_setsched=1
+        try_lockmem=1
+        add_def FREEBSD
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIME ADJUSTTIMEX SETTIME BINDSOCKET"
+        fi
+        echo "Configuring for $SYSTEM"
+    ;;
+    NetBSD)
+        EXTRA_OBJECTS="sys_generic.o sys_netbsd.o sys_timex.o sys_posix.o"
+        try_clockctl=1
+        try_setsched=1
+        try_lockmem=1
+        add_def NETBSD
+        echo "Configuring for $SYSTEM"
+    ;;
+    Darwin)
+        EXTRA_OBJECTS="sys_macosx.o"
+        LIBS="$LIBS -lresolv"
+        add_def MACOSX
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIME SETTIME BINDSOCKET"
+        fi
+        major=`echo $VERSION | cut -d. -f1`
+        # ntp_adjtime is not available in macOS 10.12 (Darwin 16.x.x) and earlier
+        if [ $major -gt "16" ]; then
+          add_def HAVE_MACOS_SYS_TIMEX
+          EXTRA_OBJECTS="$EXTRA_OBJECTS sys_generic.o sys_netbsd.o sys_timex.o"
+          if [ $feat_droproot = "1" ]; then
+            priv_ops="$priv_ops ADJUSTTIMEX"
+          fi
+        fi
+        echo "Configuring for macOS (" $SYSTEM "macOS version" $VERSION ")"
+    ;;
+    SunOS)
+        EXTRA_OBJECTS="sys_generic.o sys_solaris.o sys_timex.o sys_posix.o"
+        LIBS="$LIBS -lsocket -lnsl -lkvm -lelf -lresolv"
+        try_setsched=1
+        try_lockmem=1
+        add_def SOLARIS
+        # These are needed to have msg_control in struct msghdr
+        add_def __EXTENSIONS__
+        add_def _XOPEN_SOURCE 1
+        add_def _XOPEN_SOURCE_EXTENDED 1
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIMEX SETTIME BINDSOCKET"
+        fi
+        echo "Configuring for illumos (" $SYSTEM "SunOS version" $VERSION ")"
+    ;;                                                                        
+    * )
+        echo "error: $SYSTEM is not supported (yet?)"
+        exit 1
+    ;;
+esac
+
+if [ $feat_debug = "1" ]; then
+  add_def FEAT_DEBUG
+fi
+add_def DEBUG $feat_debug
+
+if [ $feat_cmdmon = "1" ]; then
+  add_def FEAT_CMDMON
+  EXTRA_OBJECTS="$EXTRA_OBJECTS cmdmon.o manual.o pktlength.o"
+fi
+
+if [ $feat_ntp = "1" ]; then
+  add_def FEAT_NTP
+  EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_auth.o ntp_core.o ntp_ext.o ntp_io.o ntp_sources.o"
+  if [ $feat_ntp_signd = "1" ]; then
+    add_def FEAT_SIGND
+    EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_signd.o"
+  fi
+else
+  feat_asyncdns=0
+  feat_timestamping=0
+fi
+
+if [ "$feat_cmdmon" = "1" ] || [ $feat_ntp = "1" ]; then
+  EXTRA_OBJECTS="$EXTRA_OBJECTS addrfilt.o clientlog.o keys.o nameserv.o"
+else
+  feat_ipv6=0
+fi
+
+if [ $feat_refclock = "1" ]; then
+  add_def FEAT_REFCLOCK
+  EXTRA_OBJECTS="$EXTRA_OBJECTS refclock.o refclock_phc.o refclock_pps.o refclock_shm.o refclock_sock.o"
+fi
+
+MYCC="$CC"
+MYCFLAGS="$CFLAGS"
+MYCPPFLAGS="$CPPFLAGS"
+MYLDFLAGS="$LDFLAGS"
+
+if [ "x$MYCC" = "x" ]; then
+  for cc in gcc clang cc ""; do
+    if [ "x$cc" = "x" ]; then
+      echo "error: no C compiler found"
+      exit 1
+    fi
+    MYCC=$cc
+    if test_code "$MYCC" '' '' '' ''; then
+      break
+    fi
+  done
+else
+  if ! test_code "$MYCC" '' '' '' ''; then
+    echo "error: C compiler $MYCC cannot create executables"
+    exit 1
+  fi
+fi
+
+if [ "x$MYCFLAGS" = "x" ]; then
+  MYCFLAGS="-O2 -g"
+
+  TESTCFLAGS="-D_FORTIFY_SOURCE=2 -fPIE"
+  TESTLDFLAGS="-pie -Wl,-z,relro,-z,now"
+  if test_code 'hardening compiler options' '' "$TESTCFLAGS" "$TESTLDFLAGS" ''; then
+    MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+    MYLDFLAGS="$MYLDFLAGS $TESTLDFLAGS"
+  fi
+  TESTCFLAGS="-fstack-protector-strong --param=ssp-buffer-size=4"
+  if test_code '-fstack-protector-strong' '' "$TESTCFLAGS" '' ''; then
+    MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+  else
+    TESTCFLAGS="-fstack-protector --param=ssp-buffer-size=4"
+    if test_code '-fstack-protector' '' "$TESTCFLAGS" '' ''; then
+      MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+    fi
+  fi
+fi
+
+if [ "x$MYCC" = "xgcc" ] || [ "x$MYCC" = "xclang" ]; then
+  MYCFLAGS="$MYCFLAGS -Wmissing-prototypes -Wall"
+fi
+
+if [ "x$PKG_CONFIG" = "x" ]; then
+  PKG_CONFIG=pkg-config
+fi
+
+if ! test_executable "pkg-config" $PKG_CONFIG --version; then
+  try_nettle=0
+  try_nss=0
+  try_gnutls=0
+fi
+
+if test_code '64-bit time_t' 'time.h' '' '' '
+  char x[sizeof(time_t) > 4 ? 1 : -1] = {0};
+  return x[0];'
+then
+  add_def HAVE_LONG_TIME_T 1
+
+  if [ "x$ntp_era_split" != "x" ]; then
+    split_seconds=$ntp_era_split
+    split_days=0
+  else
+    if [ "x$SOURCE_DATE_EPOCH" != "x" ]; then
+      split_seconds=$SOURCE_DATE_EPOCH
+    else
+      split_seconds=`date '+%s'`
+    fi
+    if [ "x$split_seconds" = "x" ]; then
+      echo "error: could not get current time, --with-ntp-era option is needed"
+      exit 1
+    fi
+    split_days=$((50 * 365))
+  fi
+
+  add_def NTP_ERA_SPLIT "(${split_seconds}LL - $split_days * 24 * 3600)"
+
+  date_format='+%Y-%m-%dT%H:%M:%SZ'
+
+  # Print the full NTP interval if a suitable date is found
+  if [ "x`date -u -d '1970-01-01 UTC 9 days ago 5 seconds 3 seconds' \
+    $date_format 2> /dev/null`" = "x1969-12-23T00:00:08Z" ]
+  then
+    time1="`date -u -d "1970-01-01 UTC $split_days days ago $split_seconds seconds" \
+      $date_format`"
+    time2="`date -u -d "1970-01-01 UTC $split_days days ago $split_seconds seconds 4294967296 seconds" \
+      $date_format`"
+    echo "NTP time mapped to $time1/$time2"
+  fi
+fi
+
+MATHCODE='return (int) pow(2.0, log(sqrt((double)argc)));'
+if ! test_code 'math' 'math.h' '' '' "$MATHCODE"; then
+  if test_code 'math in -lm' 'math.h' '' '-lm' "$MATHCODE"; then
+    LIBS="$LIBS -lm"
+  else
+    echo "error: could not compile/link a program which uses sqrt(), log(), pow()"
+    exit 1
+  fi
+fi
+  
+if test_code 'struct in_pktinfo' 'sys/socket.h netinet/in.h' '' '' '
+  struct in_pktinfo ipi;
+  return sizeof (ipi.ipi_spec_dst.s_addr) + IP_PKTINFO;'
+then
+  add_def HAVE_IN_PKTINFO
+fi
+
+if [ $feat_ipv6 = "1" ] && \
+  test_code 'IPv6 support' 'arpa/inet.h sys/socket.h netinet/in.h' '' "$LIBS" '
+    struct sockaddr_in6 n;
+    char p[100];
+    n.sin6_addr = in6addr_any;
+    n.sin6_scope_id = 0;
+    return !inet_ntop(AF_INET6, &n.sin6_addr.s6_addr, p, sizeof(p));'
+then
+  add_def FEAT_IPV6
+  if test_code 'struct in6_pktinfo' 'sys/socket.h netinet/in.h' '' '' '
+    return sizeof (struct in6_pktinfo) + IPV6_PKTINFO;'
+  then
+    add_def HAVE_IN6_PKTINFO
+  else
+    if test_code 'struct in6_pktinfo with _GNU_SOURCE' 'sys/socket.h netinet/in.h' \
+      '-D_GNU_SOURCE' '' 'return sizeof (struct in6_pktinfo) + IPV6_PKTINFO;'
+    then
+      add_def _GNU_SOURCE
+      add_def HAVE_IN6_PKTINFO
+    fi
+  fi
+fi
+
+if ! test_code 'O_NOFOLLOW flag' 'sys/types.h sys/stat.h fcntl.h' '' "$LIBS" \
+  'return open("/dev/null", O_NOFOLLOW);'
+then
+  if test_code 'O_NOFOLLOW flag with _GNU_SOURCE' 'sys/types.h sys/stat.h fcntl.h' \
+    '-D_GNU_SOURCE' "$LIBS" \
+    'return open("/dev/null", O_NOFOLLOW);'
+  then
+    add_def _GNU_SOURCE
+  else
+    echo "error: open() does not support O_NOFOLLOW flag"
+    exit 1
+  fi
+fi
+
+if [ $try_clock_gettime = "1" ]; then
+  if test_code 'clock_gettime()' 'time.h' '' '' \
+    'clock_gettime(CLOCK_REALTIME, (void *)1);'
+  then
+    add_def HAVE_CLOCK_GETTIME
+  else
+    if test_code 'clock_gettime() in -lrt' 'time.h' '' '-lrt' \
+      'clock_gettime(CLOCK_REALTIME, (void *)1);'
+    then
+      add_def HAVE_CLOCK_GETTIME
+      EXTRA_LIBS="$EXTRA_LIBS -lrt"
+    fi
+  fi
+fi
+
+if ! test_code 'getaddrinfo()' 'sys/types.h sys/socket.h netdb.h' '' "$LIBS" \
+  'return getaddrinfo(0, 0, 0, 0);'
+then
+  echo "error: getaddrinfo() not found"
+  exit 1
+fi
+
+if [ $feat_asyncdns = "1" ] && \
+  test_code 'pthread' 'pthread.h' '-pthread' '' '
+    pthread_t thread;
+    return (int)pthread_create(&thread, NULL, (void *)1, NULL);'
+then
+  add_def FEAT_ASYNCDNS
+  add_def USE_PTHREAD_ASYNCDNS
+  EXTRA_OBJECTS="$EXTRA_OBJECTS nameserv_async.o"
+  use_pthread=1
+fi
+
+if [ $try_arc4random = "1" ] && \
+  test_code 'arc4random_buf()' 'stdlib.h' '' '' \
+    'arc4random_buf((void *)1, 1);'
+then
+  add_def HAVE_ARC4RANDOM
+else
+  if test_code 'getrandom()' 'stdlib.h sys/random.h' '' '' \
+      'return getrandom((void *)1, 1, 0);'; then
+    add_def HAVE_GETRANDOM
+  fi
+fi
+
+RECVMMSG_CODE='
+  struct mmsghdr hdr;
+  return !recvmmsg(0, &hdr, 1, MSG_DONTWAIT, 0);'
+if [ $try_recvmmsg = "1" ]; then
+  if test_code 'recvmmsg()' 'sys/socket.h' '' "$LIBS" "$RECVMMSG_CODE"; then
+    add_def HAVE_RECVMMSG
+  else
+    if test_code 'recvmmsg() with _GNU_SOURCE' 'sys/socket.h' '-D_GNU_SOURCE' \
+      "$LIBS" "$RECVMMSG_CODE"
+    then
+      add_def _GNU_SOURCE
+      add_def HAVE_RECVMMSG
+    fi
+  fi
+fi
+
+if [ $feat_timestamping = "1" ] && [ $try_timestamping = "1" ] &&
+  test_code 'SW/HW timestamping' 'sys/types.h sys/socket.h linux/net_tstamp.h
+                                  linux/errqueue.h linux/ptp_clock.h' '' '' '
+    int val = SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_RX_SOFTWARE |
+              SOF_TIMESTAMPING_RAW_HARDWARE | SOF_TIMESTAMPING_OPT_CMSG;
+    return sizeof (struct scm_timestamping) + SCM_TSTAMP_SND + PTP_SYS_OFFSET +
+           setsockopt(0, SOL_SOCKET, SO_SELECT_ERR_QUEUE + SO_TIMESTAMPING,
+                      &val, sizeof (val));'
+then
+  add_def HAVE_LINUX_TIMESTAMPING
+  EXTRA_OBJECTS="$EXTRA_OBJECTS hwclock.o ntp_io_linux.o"
+
+  if test_code 'other timestamping options' \
+    'sys/types.h sys/socket.h linux/net_tstamp.h' '' '' '
+    struct scm_ts_pktinfo pktinfo;
+    pktinfo.if_index = pktinfo.pkt_length = 0;
+    return pktinfo.if_index + pktinfo.pkt_length + HWTSTAMP_FILTER_NTP_ALL +
+           SCM_TIMESTAMPING_PKTINFO +
+           SOF_TIMESTAMPING_OPT_PKTINFO + SOF_TIMESTAMPING_OPT_TX_SWHW;'; then
+    add_def HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP 1
+    add_def HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO 1
+    add_def HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW 1
+  fi
+fi
+
+timepps_h=""
+if [ $feat_refclock = "1" ] && [ $feat_pps = "1" ]; then
+  if test_code '<sys/timepps.h>' 'inttypes.h time.h sys/timepps.h' '' '' ''; then
+    timepps_h="sys/timepps.h"
+    add_def HAVE_SYS_TIMEPPS_H
+  else
+    if test_code '<timepps.h>' 'inttypes.h time.h timepps.h' '' '' ''; then
+      timepps_h="timepps.h"
+      add_def HAVE_TIMEPPS_H
+    fi
+  fi
+fi
+
+if [ "x$timepps_h" != "x" ] && \
+  test_code 'PPSAPI' "inttypes.h string.h time.h $timepps_h" '' '' '
+    pps_handle_t h = 0;
+    pps_info_t i;
+    struct timespec ts;
+    ts.tv_sec = ts.tv_nsec = 0;
+    return time_pps_fetch(h, PPS_TSFMT_TSPEC, &i, &ts);'
+then
+  add_def FEAT_PPS
+fi
+
+if [ $feat_droproot = "1" ] && [ $try_libcap = "1" ] && \
+  test_code \
+    libcap \
+    'sys/types.h pwd.h sys/prctl.h sys/capability.h grp.h' \
+    '' '-lcap' \
+    'prctl(PR_SET_KEEPCAPS, 1);cap_set_proc(cap_from_text("cap_sys_time=ep"));'
+then
+    add_def FEAT_PRIVDROP
+    EXTRA_LIBS="$EXTRA_LIBS -lcap"
+fi
+
+if [ $feat_droproot = "1" ] && [ $try_clockctl = "1" ] && \
+  test_code '<sys/clockctl.h>' 'sys/clockctl.h' '' '' ''
+then
+  add_def FEAT_PRIVDROP
+  priv_ops="BINDSOCKET"
+fi
+
+if [ $feat_scfilter = "1" ] && [ $try_seccomp = "1" ] && \
+  test_code seccomp 'seccomp.h' '' '-lseccomp' \
+    'seccomp_init(SCMP_ACT_KILL);'
+then
+  add_def FEAT_SCFILTER
+  if [ $feat_ntp = "1" ]; then
+    # NAME2IPADDRESS shouldn't be enabled together with a privops operation
+    # used by the main thread as the helper process works on one request at
+    # a time and the async resolver would block the main thread
+    priv_ops="NAME2IPADDRESS RELOADDNS"
+  fi
+  EXTRA_LIBS="$EXTRA_LIBS -lseccomp"
+fi
+
+if [ "x$priv_ops" != "x" ]; then
+  EXTRA_OBJECTS="$EXTRA_OBJECTS privops.o"
+  add_def PRIVOPS_HELPER
+  for o in $priv_ops; do
+    add_def PRIVOPS_$o
+  done
+fi
+
+if [ $feat_rtc = "1" ] && [ $try_rtc = "1" ] && \
+  test_code '<linux/rtc.h>' 'sys/ioctl.h linux/rtc.h' '' '' \
+    'ioctl(1, RTC_UIE_ON&RTC_UIE_OFF&RTC_RD_TIME&RTC_SET_TIME, 0&RTC_UF);'
+then
+    EXTRA_OBJECTS="$EXTRA_OBJECTS rtc_linux.o"
+    add_def FEAT_RTC
+fi
+
+if [ $feat_refclock = "1" ] && [ $feat_phc = "1" ] && [ $try_phc = "1" ] && \
+  grep '#define HAVE_CLOCK_GETTIME' config.h > /dev/null && \
+  test_code '<linux/ptp_clock.h>' 'sys/ioctl.h linux/ptp_clock.h' '' '' \
+    'ioctl(1, PTP_CLOCK_GETCAPS + PTP_SYS_OFFSET, 0);'
+then
+  grep 'HAVE_LINUX_TIMESTAMPING' config.h > /dev/null ||
+    EXTRA_OBJECTS="$EXTRA_OBJECTS hwclock.o"
+  add_def FEAT_PHC
+fi
+
+if [ $try_setsched = "1" ] && \
+  test_code \
+    'pthread_setschedparam()' \
+    'pthread.h sched.h' '-pthread' '' '
+     struct sched_param sched;
+     sched_get_priority_max(SCHED_FIFO);
+     pthread_setschedparam(pthread_self(), SCHED_FIFO, &sched);'
+then
+  add_def HAVE_PTHREAD_SETSCHEDPARAM
+  use_pthread=1
+fi
+
+if [ $try_lockmem = "1" ] && \
+  test_code \
+    'mlockall()' \
+    'sys/mman.h' '' '' '
+     mlockall(MCL_CURRENT|MCL_FUTURE);'
+then
+  add_def HAVE_MLOCKALL
+fi
+if [ $try_lockmem = "1" ] && \
+  test_code \
+    'setrlimit(RLIMIT_MEMLOCK, ...)' \
+    'sys/resource.h' '' '' '
+     struct rlimit rlim;
+     rlim.rlim_max = rlim.rlim_cur = RLIM_INFINITY;
+     setrlimit(RLIMIT_MEMLOCK, &rlim);'
+then
+  add_def HAVE_SETRLIMIT_MEMLOCK
+fi
+
+if [ $feat_forcednsretry = "1" ]
+then
+  add_def FORCE_DNSRETRY
+fi
+
+READLINE_LINK=""
+if [ $feat_readline = "1" ]; then
+  if [ $try_editline = "1" ]; then
+    if test_code editline 'stdio.h editline/readline.h' '' '-ledit' \
+      'add_history(readline("prompt"));'
+    then
+      add_def FEAT_READLINE
+      READLINE_LINK="-ledit"
+    fi
+  fi
+
+  EXTRA_CLI_LIBS="$EXTRA_CLI_LIBS $READLINE_LINK"
+fi
+
+HASH_OBJ="hash_intmd5.o"
+HASH_LINK=""
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nettle = "1" ]; then
+  test_cflags="`pkg_config --cflags nettle`"
+  test_link="`pkg_config --libs nettle`"
+  if test_code 'nettle' 'nettle/nettle-meta.h nettle/sha2.h' \
+    "$test_cflags" "$test_link" \
+    'return nettle_hashes[0]->context_size;'
+  then
+    HASH_OBJ="hash_nettle.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+
+    if test_code 'CMAC in nettle' 'nettle/cmac.h' "$test_cflags" "$test_link" \
+      'cmac128_update((void *)1, (void *)2, (void *)3, 1, (void *)4);'
+    then
+      add_def HAVE_CMAC
+      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_nettle.o"
+      EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS cmac_nettle.o"
+    fi
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nss = "1" ]; then
+  test_cflags="`pkg_config --cflags nss`"
+  test_link="`pkg_config --libs-only-L nss` -lfreebl3 -lnssutil3"
+  if test_code 'NSS' 'nss.h hasht.h nsslowhash.h' \
+    "$test_cflags" "$test_link" \
+    'NSSLOWHASH_Begin(NSSLOWHASH_NewContext(NSSLOW_Init(), HASH_AlgSHA512));'
+  then
+    HASH_OBJ="hash_nss.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_tomcrypt = "1" ]; then
+  if test_code 'tomcrypt' 'tomcrypt.h' '-I/usr/include/tomcrypt' '-ltomcrypt' \
+    'hash_memory_multi(find_hash("md5"), (void *)1, (void *)2, (void *)3, 1, (void *)4, 1);'
+  then
+    HASH_OBJ="hash_tomcrypt.o"
+    HASH_LINK="-ltomcrypt"
+    MYCPPFLAGS="$MYCPPFLAGS -I/usr/include/tomcrypt"
+    add_def FEAT_SECHASH
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_gnutls = "1" ]; then
+  test_cflags="`pkg_config --cflags gnutls`"
+  test_link="`pkg_config --libs gnutls`"
+  if test_code 'gnutls' 'gnutls/crypto.h' \
+    "$test_cflags" "$test_link" '
+      return gnutls_hash((void *)1, (void *)2, 1);'
+  then
+    HASH_OBJ="hash_gnutls.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+
+    if test_code 'CMAC in gnutls' 'gnutls/crypto.h' "$test_cflags" "$test_link" \
+      'return gnutls_hmac_init((void *)1, GNUTLS_MAC_AES_CMAC_128, (void *)2, 0);'
+    then
+      add_def HAVE_CMAC
+      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_gnutls.o"
+      EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS cmac_gnutls.o"
+    fi
+  fi
+fi
+
+EXTRA_OBJECTS="$EXTRA_OBJECTS $HASH_OBJ"
+EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS $HASH_OBJ"
+LIBS="$LIBS $HASH_LINK"
+
+if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
+  if [ "$HASH_OBJ" = "hash_gnutls.o" ]; then
+    test_cflags=""
+    test_link=""
+  else
+    test_cflags="`pkg_config --cflags gnutls`"
+    test_link="`pkg_config --libs gnutls`"
+  fi
+  if test_code 'TLS1.3 in gnutls' 'gnutls/gnutls.h' \
+    "$test_cflags" "$test_link $LIBS" '
+      return gnutls_init((void *)1, 0) + GNUTLS_TLS1_3 +
+        gnutls_priority_init2((void *)1, "", NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND) +
+        gnutls_prf_rfc5705((void *)1, 0, "", 0, "", 16, (void *)2);'
+  then
+    if test_code 'SIV in nettle' \
+      'nettle/siv-cmac.h' "" "$LIBS" \
+      'siv_cmac_aes128_set_key((void *)1, (void *)2);'
+    then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+      add_def HAVE_SIV
+      add_def HAVE_NETTLE_SIV_CMAC
+    else
+      if test_code 'SIV in gnutls' 'gnutls/crypto.h' \
+        "$test_cflags" "$test_link $LIBS" '
+          return gnutls_aead_cipher_init((void *)1, GNUTLS_CIPHER_AES_128_SIV, (void *)2);'
+      then
+        EXTRA_OBJECTS="$EXTRA_OBJECTS siv_gnutls.o"
+        add_def HAVE_SIV
+        if test_code 'gnutls_aead_cipher_set_key()' 'gnutls/crypto.h' \
+          "$test_cflags" "$test_link $LIBS" '
+            return gnutls_aead_cipher_set_key((void *)1, (void *)2);'
+        then
+          add_def HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+        fi
+      else
+        if test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
+          'aes128_set_encrypt_key((void *)1, (void *)2);'
+        then
+          EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+          add_def HAVE_SIV
+        fi
+      fi
+    fi
+
+    if grep '#define HAVE_SIV' config.h > /dev/null; then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
+      LIBS="$LIBS $test_link"
+      MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+      add_def FEAT_NTS
+    fi
+  fi
+fi
+
+if [ $use_pthread = "1" ]; then
+  MYCFLAGS="$MYCFLAGS -pthread"
+fi
+
+SYSCONFDIR=/etc
+if [ "x$SETSYSCONFDIR" != "x" ]; then
+  SYSCONFDIR=$SETSYSCONFDIR
+fi
+
+PREFIX=/usr/local
+if [ "x$SETPREFIX" != "x" ]; then
+  PREFIX=$SETPREFIX
+fi
+
+EPREFIX=${PREFIX}
+if [ "x$SETEPREFIX" != "x" ]; then
+  EPREFIX=$SETEPREFIX
+fi
+
+BINDIR=${EPREFIX}/bin
+if [ "x$SETBINDIR" != "x" ]; then
+  BINDIR=$SETBINDIR
+fi
+
+SBINDIR=${EPREFIX}/sbin
+if [ "x$SETSBINDIR" != "x" ]; then
+  SBINDIR=$SETSBINDIR
+fi
+
+DATAROOTDIR=${PREFIX}/share
+if [ "x$SETDATAROOTDIR" != "x" ]; then
+  DATAROOTDIR=$SETDATAROOTDIR
+fi
+
+MANDIR=${DATAROOTDIR}/man
+if [ "x$SETMANDIR" != "x" ]; then
+  MANDIR=$SETMANDIR
+fi
+
+DOCDIR=${DATAROOTDIR}/doc/chrony
+if [ "x$SETDOCDIR" != "x" ]; then
+  DOCDIR=$SETDOCDIR
+fi
+
+LOCALSTATEDIR=/var
+if [ "x$SETLOCALSTATEDIR" != "x" ]; then
+  LOCALSTATEDIR=$SETLOCALSTATEDIR
+fi
+
+CHRONYRUNDIR=${LOCALSTATEDIR}/run/chrony
+if [ "x$SETCHRONYRUNDIR" != "x" ]; then
+  CHRONYRUNDIR=$SETCHRONYRUNDIR
+fi
+
+CHRONYVARDIR=${LOCALSTATEDIR}/lib/chrony
+if [ "x$SETCHRONYVARDIR" != "x" ]; then
+  CHRONYVARDIR=$SETCHRONYVARDIR
+fi
+
+add_def DEFAULT_CONF_FILE "\"$SYSCONFDIR/chrony.conf\""
+add_def DEFAULT_HWCLOCK_FILE "\"$default_hwclockfile\""
+add_def DEFAULT_PID_FILE "\"$default_pidfile\""
+add_def DEFAULT_RTC_DEVICE "\"$default_rtcdevice\""
+add_def DEFAULT_USER "\"$default_user\""
+add_def DEFAULT_COMMAND_SOCKET "\"$CHRONYRUNDIR/chronyd.sock\""
+add_def MAIL_PROGRAM "\"$mail_program\""
+
+common_features="`get_features SECHASH IPV6 DEBUG`"
+chronyc_features="`get_features READLINE`"
+chronyd_features="`get_features CMDMON NTP REFCLOCK RTC PRIVDROP SCFILTER SIGND ASYNCDNS NTS`"
+add_def CHRONYC_FEATURES "\"$chronyc_features $common_features\""
+add_def CHRONYD_FEATURES "\"$chronyd_features $common_features\""
+echo "Features : $chronyd_features $chronyc_features $common_features"
+
+if [ -f version.txt ]; then
+  CHRONY_VERSION="`cat version.txt`"
+else
+  CHRONY_VERSION="DEVELOPMENT"
+fi
+
+add_def CHRONY_VERSION "\"${CHRONY_VERSION}\""
+
+for f in Makefile doc/Makefile test/unit/Makefile
+do
+  echo Creating $f
+  sed -e "s%@EXTRA_OBJS@%${EXTRA_OBJECTS}%;\
+          s%@EXTRA_CLI_OBJS@%${EXTRA_CLI_OBJECTS}%;\
+          s%@CC@%${MYCC}%;\
+          s%@CFLAGS@%${MYCFLAGS}%;\
+          s%@CPPFLAGS@%${MYCPPFLAGS}%;\
+          s%@LDFLAGS@%${MYLDFLAGS}%;\
+          s%@LIBS@%${LIBS}%;\
+          s%@EXTRA_LIBS@%${EXTRA_LIBS}%;\
+          s%@EXTRA_CLI_LIBS@%${EXTRA_CLI_LIBS}%;\
+          s%@SYSCONFDIR@%${SYSCONFDIR}%;\
+          s%@BINDIR@%${BINDIR}%;\
+          s%@SBINDIR@%${SBINDIR}%;\
+          s%@DOCDIR@%${DOCDIR}%;\
+          s%@MANDIR@%${MANDIR}%;\
+          s%@LOCALSTATEDIR@%${LOCALSTATEDIR}%;\
+          s%@CHRONYRUNDIR@%${CHRONYRUNDIR}%;\
+          s%@CHRONYVARDIR@%${CHRONYVARDIR}%;\
+          s%@DEFAULT_HWCLOCK_FILE@%${default_hwclockfile}%;\
+          s%@DEFAULT_PID_FILE@%${default_pidfile}%;\
+          s%@DEFAULT_RTC_DEVICE@%${default_rtcdevice}%;\
+          s%@DEFAULT_USER@%${default_user}%;\
+          s%@CHRONY_VERSION@%${CHRONY_VERSION}%;" \
+          < ${f}.in > $f
+done
+
+# =======================================================================
+# vim:et:sw=2:ht=2:sts=2:fdm=marker:cms=#%s
+
diff --git a/contrib/andrew_bishop_1 b/contrib/andrew_bishop_1
new file mode 100644
index 0000000..4c0b437
--- /dev/null
+++ b/contrib/andrew_bishop_1
@@ -0,0 +1,114 @@
+From amb@gedanken.demon.co.uk Tue Aug 17 22:14:00 1999
+Date: Fri, 6 Aug 1999 19:00:24 +0100
+From: Andrew M. Bishop <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: Re: Chrony and laptop configuration
+
+Hi,
+
+Attached is the apmd_proxy script from the apmd-3.0beta9 distribution.
+
+The changes that I would make are the following:
+
+Replace the update_clock function (line 122) with 
+
+update_clock () {
+
+chronyd -f /etc/chrony.conf
+
+}
+
+Around line 171 (in the suspend actions section) I would kill chronyd.
+
+begin 644 apmd_proxy.gz
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+>Z]AB9"M2/=L.+(S7D<0S_V\81H;_`M>*^#$A)0``
+`
+end
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+
diff --git a/contrib/andrew_bishop_2 b/contrib/andrew_bishop_2
new file mode 100644
index 0000000..d3ede74
--- /dev/null
+++ b/contrib/andrew_bishop_2
@@ -0,0 +1,95 @@
+From amb@gedanken.demon.co.uk Wed Sep  1 22:26:59 1999
+Date: Thu, 19 Aug 1999 17:30:14 +0100
+From: Andrew M. Bishop <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: [amb@gedanken.demon.co.uk: Chrony and laptop configuration]
+
+Hi,
+
+What you need to do is replace 10.0.0.0 with the network of the
+freeserve nameservers in the two scripts below.
+
+Other than that you can use it as is.
+
+------- Start of forwarded message -------
+From: "Andrew M. Bishop" <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: Chrony and laptop configuration
+Date: Sat, 31 Jul 1999 11:02:04 +0100
+
+Attached are the ip-up and ip-down files that I use for chrony.
+(Actually because of the way that debian works they are separate file
+in the /etc/ppp/ip-up.d directory that are run in a SysV init style).
+
+They rely on the presence of an 'ipparam demon' or 'ipparam freeserve'
+line in the PPP options file.
+
+-------------------- /etc/ppp/ip-up --------------------
+#!/bin/sh -f
+#
+# A script to start chrony
+#
+
+PPP_IPPARAM="$6"
+
+if [ $PPP_IPPARAM = "demon" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+online 255.255.255.0/158.152.1.0
+online 255.255.255.0/194.159.253.0
+EOF
+
+fi
+
+if [ $PPP_IPPARAM = "freeserve" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+online 255.255.255.0/10.0.0.0
+EOF
+
+fi
+-------------------- /etc/ppp/ip-up --------------------
+
+-------------------- /etc/ppp/ip-down --------------------
+#!/bin/sh -f
+#
+# A script to stop chrony
+#
+
+PPP_IPPARAM="$6"
+
+if [ $PPP_IPPARAM = "demon" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+offline 255.255.255.0/158.152.1.0
+offline 255.255.255.0/194.159.253.0
+EOF
+
+fi
+
+if [ $PPP_IPPARAM = "freeserve" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+offline 255.255.255.0/10.0.0.0
+EOF
+
+fi
+-------------------- /etc/ppp/ip-down --------------------
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+------- End of forwarded message -------
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+
diff --git a/contrib/bryan_christianson_1/README.txt b/contrib/bryan_christianson_1/README.txt
new file mode 100644
index 0000000..3a0a2ef
--- /dev/null
+++ b/contrib/bryan_christianson_1/README.txt
@@ -0,0 +1,103 @@
+Notes for installing chrony on macOS
+Author: Bryan Christianson (bryan@whatroute.net)
+------------------------------------------------
+
+These files are for those admins/users who would prefer to install chrony
+from the source distribution and are intended as guidelines rather than
+being definitive. They can be edited with a plain text editor, such as
+vi, emacs or your favourite IDE (Xcode)
+
+It is assumed you are comfortable with installing software from the
+terminal command line and know how to use sudo to acquire root access.
+
+If you are not familiar with the macOS command line then
+please consider using ChronyControl from http://whatroute.net/chronycontrol.html
+
+ChronyControl provides a gui wrapper for installing these files and sets the
+necessary permissions on each file.
+
+
+Install the chrony software
+---------------------------
+
+You will need xcode and the commandline additions to build and install chrony.
+These can be obtained from Apple's website via the App Store.
+
+cd to the chrony directory
+./configure
+make
+sudo make install
+
+chrony is now installed in default locations (/usr/local/sbin/chronyd,
+/usr/local/bin/chronyc)
+
+Create a chrony.conf file - see the chrony website for details
+
+The support files here assume the following directives are specified in the
+chrony.conf file
+
+keyfile /etc/chrony.d/chrony.keys
+driftfile /var/db/chrony/chrony.drift
+bindcmdaddress /var/db/chrony/chronyd.sock
+logdir /var/log/chrony
+dumpdir /var/db/chrony
+
+Install this file as /etc/chrony.d/chrony.conf and create
+the directories specified in the above directives if they don't exist.
+You will need root permissions to create the directories.
+
+
+Running chronyd
+---------------
+At this point chronyd *could* be run as a daemon. Apple discourage running
+daemons and their preferred method uses the launchd facility. The
+support files here provide a launchd configuration file for chronyd and also
+a shell script and launchd configuration file to rotate the chronyd logs on a daily basis.
+
+
+Support files
+-------------
+Dates and sizes may differ
+-rw-r--r--  1 yourname  staff  2084  4 Aug 22:54 README.txt
+-rwxr-xr-x  1 yourname  staff   676  4 Aug 21:18 chronylogrotate.sh
+-rw-r--r--  1 yourname  staff   543 18 Jul 20:10 org.tuxfamily.chronyc.plist
+-rw-r--r--  1 yourname  staff   511 19 Jun 18:30 org.tuxfamily.chronyd.plist
+
+If you have used chrony support directories other than those suggested, you
+will need to edit each file and make the appropriate changes.
+
+
+Installing the support files
+----------------------------
+
+1. chronylogrotate.sh
+This is a simple shell script that deletes old log files. Unfortunately because
+of the need to run chronyc, the standard macOS logrotation does not work with
+chrony logs.
+
+This script runs on a daily basis under control of launchd and should be
+installed in the /usr/local/bin directory
+
+sudo cp chronylogrotate.sh /usr/local/bin
+sudo chmod +x /usr/local/bin/chronylogrotate.sh
+sudo chown root:wheel /usr/local/bin/chronylogrotate.sh
+
+
+2. org.tuxfamily.chronyc.plist
+This file is the launchd plist that runs logrotation each day. You may
+wish to edit this file to change the time of day at which the rotation
+will run, currently 04:05 am
+
+sudo cp org.tuxfamily.chronyc.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
+
+
+3. org.tuxfamily.chronyd.plist
+This file is the launchd plist that runs chronyd when the Macintosh starts.
+
+sudo cp org.tuxfamily.chronyd.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
diff --git a/contrib/bryan_christianson_1/chronylogrotate.sh b/contrib/bryan_christianson_1/chronylogrotate.sh
new file mode 100755
index 0000000..f919544
--- /dev/null
+++ b/contrib/bryan_christianson_1/chronylogrotate.sh
@@ -0,0 +1,58 @@
+#!/bin/sh
+
+#  chronyd/chronyc - Programs for keeping computer clocks accurate.
+#
+#  **********************************************************************
+#  * Copyright (C) Bryan Christianson  2015
+#  *
+#  * This program is free software; you can redistribute it and/or modify
+#  * it under the terms of version 2 of the GNU General Public License as
+#  * published by the Free Software Foundation.
+#  *
+#  * This program is distributed in the hope that it will be useful, but
+#  * WITHOUT ANY WARRANTY; without even the implied warranty of
+#  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#  * General Public License for more details.
+#  *
+#  * You should have received a copy of the GNU General Public License along
+#  * with this program; if not, write to the Free Software Foundation, Inc.,
+#  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#  *
+#  **********************************************************************
+
+LOGDIR=/var/log/chrony
+
+rotate () {
+  prefix=$1
+
+  rm -f $prefix.log.10
+
+  for (( count=9; count>= 0; count-- ))
+  do
+    next=$(( $count+1 ))
+    if [ -f $prefix.log.$count ]; then
+      mv $prefix.log.$count $prefix.log.$next
+    fi
+  done
+
+  if [ -f $prefix.log ]; then
+    mv $prefix.log $prefix.log.0
+  fi
+}
+
+if [ ! -e "$LOGDIR" ]; then
+  logger -s "missing directory: $LOGDIR"
+  exit 1
+fi
+
+cd $LOGDIR
+
+rotate measurements
+rotate statistics
+rotate tracking
+
+#
+# signal chronyd via chronyc
+/usr/local/bin/chronyc cyclelogs > /dev/null
+
+exit $?
\ No newline at end of file
diff --git a/contrib/bryan_christianson_1/org.tuxfamily.chronyc.plist b/contrib/bryan_christianson_1/org.tuxfamily.chronyc.plist
new file mode 100644
index 0000000..a3c42c6
--- /dev/null
+++ b/contrib/bryan_christianson_1/org.tuxfamily.chronyc.plist
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Label</key>
+	<string>org.tuxfamily.logrotate</string>
+	<key>KeepAlive</key>
+	<false/>
+	<key>ProgramArguments</key>
+	<array>
+		<string>/bin/sh</string>
+		<string>/usr/local/bin/chronylogrotate.sh</string>
+	</array>
+	<key>StartCalendarInterval</key>
+	<dict>
+		<key>Minute</key>
+		<integer>5</integer>
+		<key>Hour</key>
+		<integer>4</integer>
+	</dict>
+</dict>
+</plist>
diff --git a/contrib/bryan_christianson_1/org.tuxfamily.chronyd.plist b/contrib/bryan_christianson_1/org.tuxfamily.chronyd.plist
new file mode 100644
index 0000000..2bf42aa
--- /dev/null
+++ b/contrib/bryan_christianson_1/org.tuxfamily.chronyd.plist
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Label</key>
+	<string>org.tuxfamily.chronyd</string>
+	<key>Program</key>
+	<string>/usr/local/sbin/chronyd</string>
+	<key>ProgramArguments</key>
+	<array>
+		<string>chronyd</string>
+		<string>-n</string>
+		<string>-f</string>
+		<string>/private/etc/chrony.d/chrony.conf</string>
+	</array>
+	<key>KeepAlive</key>
+	<true/>
+</dict>
+</plist>
diff --git a/contrib/erik_bryer_1 b/contrib/erik_bryer_1
new file mode 100644
index 0000000..c551dfe
--- /dev/null
+++ b/contrib/erik_bryer_1
@@ -0,0 +1,65 @@
+#!/bin/sh
+#
+# chrony        Start time synchronization. This script
+#               starts chronyd.
+#
+# Hacked by:    Erik Bryer <ebryer@spots.ab.ca> using inet as a template
+#
+# chkconfig: 2345 02 82
+# description: chronyd helps keep the system time accurate by calculating \
+#              and applying correction factors to compensate for the drift \
+#              in the clock. chronyd can also correct the hardware clock \
+#              (RTC) on some systems.
+# processname: chronyd
+# config: /etc/chrony.conf
+
+# Source function library.
+. /etc/rc.d/init.d/functions
+
+# Source networking configuration.
+. /etc/sysconfig/network
+
+# Set path to include chronyd in /usr/local/sbin
+PATH="$PATH:/usr/local/sbin"
+
+[ -f /usr/local/sbin/chronyd ] || exit 0
+
+[ -f /etc/chrony.conf ] || exit 0
+
+RETVAL=0
+
+# See how we were called.
+case "$1" in
+  start)
+        # Start daemons.
+        echo -n "Starting chronyd: "
+        daemon chronyd
+	RETVAL=$?
+ 	[ $RETVAL -eq 0 ] && touch /var/lock/subsys/chrony
+	echo
+        ;;
+  stop)
+        # Stop daemons.
+        echo -n "Shutting down chronyd: "
+# If not dead killproc automatically sleeps for 4.1 seconds then does 
+# kill -9. "chrony.txt" prefers a 5 second delay, but this should be ok.
+        killproc chronyd -15
+	RETVAL=$?
+	[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/chrony
+        echo
+        ;;
+  status)
+	status chronyd
+	exit $?
+	;;
+  restart)
+	$0 stop
+	$0 start
+	;;
+  *)
+        echo "Usage: named {start|stop|status|restart}"
+        exit 1
+esac
+
+exit $RETVAL
+
diff --git a/contrib/ken_gillett_1 b/contrib/ken_gillett_1
new file mode 100644
index 0000000..48b7999
--- /dev/null
+++ b/contrib/ken_gillett_1
@@ -0,0 +1,100 @@
+#!/bin/sh
+#
+# chronyd      This shell script takes care of starting and stopping
+#              chronyd (NTP daemon).
+#
+# chkconfig: 45 80 20
+# description: chronyd is the NTP daemon.
+
+# Source function library.
+. /etc/rc.d/init.d/functions
+
+# Source networking configuration.
+. /etc/sysconfig/network
+
+# Check that networking is up.
+[ ${NETWORKING} = "no" ] && exit 0
+
+PREDIR="/usr/local"
+CHRONYD=$PREDIR"/sbin/chronyd"
+CHRONYC=$PREDIR"/bin/chronyc"
+
+[ -x $CHRONYD -a -x $CHRONYC -a -f /etc/chrony.conf ] || exit 0
+
+dochrony() {
+	if [ -z "$(pidofproc chronyd)" ]; then
+		echo -e "\n\tchronyd not running\n\n"
+		exit 2
+	fi
+	KEY=`awk '$1 == "commandkey" {print $2; exit}' /etc/chrony.conf`
+	PASSWORD=`awk '$1 == '$KEY' {print $2; exit}' /etc/chrony/keys`
+
+	$CHRONYC <<- EOF
+		password $PASSWORD
+		$@
+		quit
+	EOF
+}
+
+# make the first parameter' lower case
+set - `echo $1 | awk '{print tolower($1)}';shift;echo "$@"`
+
+# Expand any shortcuts.
+case "$1" in
+   on|1)
+	set - "online"
+	;;
+   off|0)
+	set - "offline"
+esac
+
+# See how we were called.
+case "$1" in
+   start)
+         # Start daemons.
+         echo -n "Starting chronyd: "
+         daemon $CHRONYD
+	if [ $? -eq 0 ]; then
+		echo $(pidofproc chronyd) > /var/run/chronyd.pid
+		touch /var/lock/subsys/chronyd
+	fi
+         echo
+         ;;
+   stop)
+         # Stop daemons.
+         echo -n "Shutting down chronyd: "
+	killproc chronyd
+         echo
+         rm -f /var/lock/subsys/chronyd
+         ;;
+   status)
+	status chronyd
+	;;
+   restart|reload)
+	$0 stop
+	$0 start
+	;;
+   condrestart)
+	if [ -f /var/lock/subsys/chronyd ]; then
+		$0 stop
+		$0 start
+	fi
+	;;
+   "")
+	echo "Usage: chronyd 
+{start|stop|restart|reload|condrestart|status|[on|off]line etc}"
+	exit 1
+	;;
+ 
+accheck|cmdaccheck|clients|manual|rtcdata|sources|sourcestats|tracking|clients)
+	dochrony "$@"
+	;;
+   *)
+         echo -n "Chrony $1: "
+	dochrony "$@" > /dev/null
+	[ $? -eq 0 ] && echo_success || echo_failure
+	echo
+esac
+
+exit 0
+
diff --git a/contrib/stephan_boettcher_1 b/contrib/stephan_boettcher_1
new file mode 100644
index 0000000..e5eda11
--- /dev/null
+++ b/contrib/stephan_boettcher_1
@@ -0,0 +1,162 @@
+From stephan@nevis1.nevis.columbia.edu Mon Jun  7 20:51:57 1999
+Date: 04 Jun 1999 00:17:25 -0400
+From: Stephan I. Boettcher <stephan@nevis1.nevis.columbia.edu>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: chrony 1.1 sysV startup script for notebooks
+
+
+Dear Richard,
+
+I installed chrony on my notebook, running RedHat 5.1 Linux.
+It looks like it works.  No problems.
+
+Thank you!
+
+I like to donate my sysV startup script, appended below.
+
+Special feature:  the `online' command scans the config file to
+selectively turn some servers online, depending on the pcmcia SCHEME.
+
+booting:                 /etc/rc.d/init.d/chrony start
+/etc/ppp/ip-up:          /etc/rc.d/init.d/chrony online
+/etc/ppp/ip-down:        /etc/rc.d/init.d/chrony offline
+logrotate cron:          /etc/rc.d/init.d/chrony cyclelogs
+a user:                  /etc/rc.d/init.d/chrony status
+a sysadmin:              /etc/rc.d/init.d/chrony restart
+shutdown:                /etc/rc.d/init.d/chrony stop
+
+Best regards
+Stephan
+
+-- 
+
+------------------------------------------------------------------------
+Stephan Boettcher                                   FAX: +1-914-591-4540
+Columbia University, Nevis Labs                     Tel: +1-914-591-2863
+P.O. Box 137, 136 South Broadway      mailto:stephan@nevis1.columbia.edu
+Irvington, NY 10533, USA          http://www.nevis.columbia.edu/~stephan
+------------------------------------------------------------------------
+
+########################### cut here ###################################
+#! /bin/bash
+#
+#  /etc/rc.d/init.d/chrony
+#
+#  SYS V startup script for  
+#  chrony ntp daemon 
+#  on Linux 2.0.3x notebooks with pcmcia scheme support
+#  $Id: stephan_boettcher_1,v 1.1 2000/04/24 21:36:04 richard Exp $
+#
+#  1999-06-02 SiB <stephan@nevis1.columbia.edu>
+#
+# For PCMCIA users:
+# In /etc/chrony.conf, precede the server commands for each SCHEME 
+# with a comment line that contains the word SCHEME and the name of
+# the scheme(s) that should use the servers, up to the next line that
+# contains the word SCHEME.  The servers must be `offline' and 
+# specified by their IP address.  The hostname will not do.
+#
+# Like:
+#
+#	# SCHEME nevisppp nevislan
+#	#       stephanpc.nevis.columbia.edu
+#	server  192.12.82.222   offline
+#
+#	# SCHEME desyppp desylan
+#
+#	#       dsygw2.desy.de
+#	server  131.169.30.15   offline
+#	#       dscomsa.desy.de
+#	server  131.169.197.35  offline
+
+CONF=/etc/chrony.conf
+CHRONYD=/usr/local/sbin/chronyd
+CHRONYC=/usr/local/bin/chronyc
+KEYS=/etc/chrony.keys
+
+# See if we got all we need:
+
+[ -f $CHRONYD -a -f $CHRONYC -a -r $CONF ] || exit
+
+
+[ -r $KEYS ]							\
+&& CMDKEY=`awk '/^commandkey/{print $2}' $CONF`			\
+&& PASSWORD=`awk -v KEY=$CMDKEY '$1==KEY{print $2}' $KEYS`
+
+
+case "$1" in
+
+  start)
+	echo -n "Starting chronyd "
+        $CHRONYD -r -s -f $CONF
+        echo
+        ;;
+
+  stop)
+        echo -n "Shutting down chronyd "
+	/usr/bin/killall chronyd
+        echo
+        ;;
+
+  restart)
+	$0 stop
+	$0 start
+	;;
+
+  on*)
+
+	[ -f /var/run/pcmcia-scheme ] && SCHEME=`cat /var/run/pcmcia-scheme`
+
+	awk  -v SCHEME=${SCHEME:-default}  -v PASSWORD=$PASSWORD  \
+		'
+		BEGIN { 
+			SEL=1;
+			print "password", PASSWORD; 
+		}
+		/SCHEME/ { 
+			SEL=match($0, SCHEME); 
+		}
+		SEL && /^server[ \t]*[0-9.]+[ \t].*offline/ { 
+			print "online 255.255.255.255/"  $2; 
+		}
+		'	\
+		$CONF	\
+	| $CHRONYC
+
+	;;
+
+  off*)
+	cat <<-EOF | $CHRONYC
+		password $PASSWORD
+		offline
+		trimrtc
+		dump
+		EOF
+	;;
+
+  *log*)
+	cat <<-EOF | $CHRONYC
+		password $PASSWORD
+		cyclelogs
+		EOF
+	;;
+
+  stat*)
+	cat <<-EOF | $CHRONYC
+		sources
+		sourcestats
+		tracking
+		rtcdata
+		EOF
+	;;
+
+  *)
+        echo "Usage: chronyd {start|stop|restart|status|online|offline|cyclelogs}"
+        exit 1
+	;;
+
+esac
+
+exit 0
+
+
diff --git a/contrib/wolfgang_weisselberg1 b/contrib/wolfgang_weisselberg1
new file mode 100644
index 0000000..2c41752
--- /dev/null
+++ b/contrib/wolfgang_weisselberg1
@@ -0,0 +1,118 @@
+
+> Is it possible to limit chronyc to only those commands that
+> are readonly plus those necessary to bring a dialup connection up
+> and down? That is: online offline dump writertc and password.
+
+This is trivial on the same host and workable for non-local
+hosts: use a wrapper program or script.  An *untested*
+sample follows.  To use it, best create a special user (say
+chronyc) and a special group (say chronyg).  Make the script
+chronyc:chronyg, and 4750 (suid, rwxr-x---).  Add all users
+who may run the script to the group chronyg.
+
+Make a chrony password file e.g.
+/usr/local/etc/chrony_password.  It should be owned by chronyc
+and readable only for the owner, containing only the chrony
+password (and maybe a newline) in the first line.
+
+In this way only the script (call it run_chrony, for example)
+can read the password.  It will allow only those commands you
+explicitely allow.  You can add a password check -- especially
+if you add an internet port so you can access it over the
+internet this is advisable.  You really want to add logging
+to this untested script as well.
+
+
+BTW, if you use some sort of PPP, you probably can use
+/etc/ppp/ip-up and /etc/ppp/ip-down to transparently set chrony
+on- and offline as the ip connection goes up and comes down.
+This is _far_ more user friendly, IMHO, and a DOS by switching
+chrony offline all the time is avoided as well.
+
+
+#! /usr/bin/perl -T
+use v5.6.1;
+use warnings;
+use strict;
+
+sub laundered_command();
+sub order_chrony($$);
+sub read_password();
+sub usage($);
+
+our $CHRONY = "/usr/local/bin/chronyc";
+
+# NOTE: select the file system protection wisely for the
+# PASSWORDFILE!
+our $PASSWORDFILE = "/usr/local/etc/chrony_password";
+
+our @ALLOWED_COMMANDS = (
+    'online',                 # switch online mode on
+    'offline',                # switch online mode off
+    'dump',                   # save measurements to file
+    'writerc',                # save RTC accumulated data
+
+    'clients',                # which clients are served by us?
+    'rtcdata',                # Quality of RTC measurements
+    'sources(?: -v)?',        # Show our sources (verbose)
+    'sourcestats(?: -v)?',    # How good are our sources (verbose)?
+    'tracking',               # whom do we adjust to?
+
+    # 'burst \d+/\d+',          # allow them to send bursts?
+);
+
+usage("No command given.") unless $ARGV[0];
+
+%ENV = ();    # nuke all environment variables.  Rather
+              # drastic, but better safe than sorry!
+              # Add whatever you really need to get it
+              # working (again).
+$ENV{'PATH'} = '/usr/local/bin:/bin:/usr/bin';
+
+order_chrony(laundered_command(), read_password());
+
+exit 0; # command succeeded
+                        
+############################################################
+
+sub usage($) {
+    print STDERR "Error: ", shift, "\n";
+
+    # OK, this eats the -v...
+    print STDERR "Legal commands are:\n\t", join "\n",
+      map { $_ =~ m:(\w+):; $1 } @ALLOWED_COMMANDS;
+    exit 1;     # error
+}
+
+############################################################
+
+sub laundered_command() {
+    my $regexp = "^(" . join ( "|", @ALLOWED_COMMANDS ) . ")\$";
+    my $parameters = join " ", @ARGV;
+    $parameters =~ m:$regexp: or usage("Command $parameters not allowed.");
+
+    return $1;    # this value, then, is untainted.
+};
+
+############################################################
+
+sub read_password() {
+    open PASS, $PASSWORDFILE
+      or die "Could not read protected password file: $!";
+    my $password = <PASS>;
+    chomp $password;
+    return $password;
+};
+
+############################################################
+
+sub order_chrony($$) {
+    my ($clean_command, $password) = @_;
+    open CHRONY, "| $CHRONY &> /dev/null" or die "could not run $CHRONY: $!\n";
+    print CHRONY "password $password\n";
+    print CHRONY "$clean_command\n";
+    close CHRONY
+      or die "Error running command $clean_command\n", "\ton $CHRONY: $!\n";
+}
+
+############################################################
diff --git a/doc/Makefile.in b/doc/Makefile.in
new file mode 100644
index 0000000..1777da5
--- /dev/null
+++ b/doc/Makefile.in
@@ -0,0 +1,76 @@
+ADOC = asciidoctor
+ADOC_FLAGS =
+SED = sed
+HTML_TO_TXT = w3m -dump -T text/html
+
+MAN_FILES = chrony.conf.man chronyc.man chronyd.man
+TXT_FILES = faq.txt installation.txt
+HTML_FILES = $(MAN_FILES:%.man=%.html) $(TXT_FILES:%.txt=%.html)
+MAN_IN_FILES = $(MAN_FILES:%.man=%.man.in)
+
+SYSCONFDIR = @SYSCONFDIR@
+BINDIR = @BINDIR@
+SBINDIR = @SBINDIR@
+MANDIR = @MANDIR@
+DOCDIR = @DOCDIR@
+CHRONYRUNDIR = @CHRONYRUNDIR@
+CHRONYVARDIR = @CHRONYVARDIR@
+CHRONY_VERSION = @CHRONY_VERSION@
+DEFAULT_USER = @DEFAULT_USER@
+DEFAULT_HWCLOCK_FILE = @DEFAULT_HWCLOCK_FILE@
+DEFAULT_PID_FILE = @DEFAULT_PID_FILE@
+DEFAULT_RTC_DEVICE = @DEFAULT_RTC_DEVICE@
+
+SED_COMMANDS = "s%\@SYSCONFDIR\@%$(SYSCONFDIR)%g;\
+	       s%\@BINDIR\@%$(BINDIR)%g;\
+	       s%\@SBINDIR\@%$(SBINDIR)%g;\
+	       s%\@CHRONY_VERSION\@%$(CHRONY_VERSION)%g;\
+	       s%\@DEFAULT_HWCLOCK_FILE\@%$(DEFAULT_HWCLOCK_FILE)%g;\
+	       s%\@DEFAULT_PID_FILE\@%$(DEFAULT_PID_FILE)%g;\
+	       s%\@DEFAULT_RTC_DEVICE\@%$(DEFAULT_RTC_DEVICE)%g;\
+	       s%\@DEFAULT_USER\@%$(DEFAULT_USER)%g;\
+	       s%\@CHRONYRUNDIR\@%$(CHRONYRUNDIR)%g;\
+	       s%\@CHRONYVARDIR\@%$(CHRONYVARDIR)%g;"
+
+man: $(MAN_FILES) $(MAN_IN_FILES)
+html: $(HTML_FILES)
+txt: $(TXT_FILES)
+docs: man html
+
+%.html: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b html -o - $< | $(SED) -e $(SED_COMMANDS) > $@
+
+%.man.in: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b manpage -o $@ $<
+
+%.man: %.man.in
+	$(SED) -e $(SED_COMMANDS) < $< > $@
+
+%.txt: %.html
+	$(HTML_TO_TXT) < $< > $@
+
+install: $(MAN_FILES)
+	[ -d $(DESTDIR)$(MANDIR)/man1 ] || mkdir -p $(DESTDIR)$(MANDIR)/man1
+	[ -d $(DESTDIR)$(MANDIR)/man5 ] || mkdir -p $(DESTDIR)$(MANDIR)/man5
+	[ -d $(DESTDIR)$(MANDIR)/man8 ] || mkdir -p $(DESTDIR)$(MANDIR)/man8
+	cp chronyc.man $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	chmod 644 $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	cp chronyd.man $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	chmod 644 $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	cp chrony.conf.man $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+	chmod 644 $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+
+install-docs: $(HTML_FILES)
+	[ -d $(DESTDIR)$(DOCDIR) ] || mkdir -p $(DESTDIR)$(DOCDIR)
+	for f in $(HTML_FILES); do \
+	  cp $$f $(DESTDIR)$(DOCDIR); \
+	  chmod 644 $(DESTDIR)$(DOCDIR)/$$f; \
+	done
+
+clean:
+	rm -f $(MAN_FILES) $(TXT_FILES) $(HTML_FILES)
+	rm -f $(MAN_IN_FILES)
+
+distclean:
+	rm -f $(MAN_FILES) $(TXT_FILES) $(HTML_FILES)
+	rm -f Makefile
diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc
new file mode 100644
index 0000000..2cf5326
--- /dev/null
+++ b/doc/chrony.conf.adoc
@@ -0,0 +1,3071 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Stephen Wadeley  2016
+// Copyright (C) Bryan Christianson  2017
+// Copyright (C) Miroslav Lichvar  2009-2022
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chrony.conf(5)
+:doctype: manpage
+:man manual: Configuration Files
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+chrony.conf - chronyd configuration file
+
+== SYNOPSIS
+*chrony.conf*
+
+== DESCRIPTION
+
+This file configures the *chronyd* daemon. The compiled-in location is
+_@SYSCONFDIR@/chrony.conf_. Other locations can be specified on the
+*chronyd* command line with the *-f* option.
+
+Each directive in the configuration file is placed on a separate line. The
+following sections describe each of the directives in turn. The directives are
+not case-sensitive. Generally, the directives can occur in any order in the file
+and if a directive is specified multiple times, only the last one will be
+effective. Exceptions are noted in the descriptions.
+
+The configuration directives can also be specified directly on the *chronyd*
+command line. In this case each argument is parsed as a new line and the
+configuration file is ignored.
+
+While the number of supported directives is large, only a few of them are
+typically needed. See the <<examples,*EXAMPLES*>> section for configuration in
+typical operating scenarios.
+
+The configuration file might contain comment lines. A comment line is any line
+that starts with zero or more spaces followed by any one of the following
+characters: *!*, *;*, *#*, *%*. Any line with this format will be ignored.
+
+== DIRECTIVES
+
+=== Time sources
+
+[[server]]*server* _hostname_ [_option_]...::
+The *server* directive specifies an NTP server which can be used as a time
+source. The client-server relationship is strictly hierarchical: a client might
+synchronise its system time to that of the server, but the server's system time
+will never be influenced by that of a client.
++
+The server can be specified by its hostname or IP address. If the hostname cannot
+be resolved on start, *chronyd* will try it again in increasing intervals, and
+also when the <<chronyc.adoc#online,*online*>> command is issued in *chronyc*.
++
+The DNS record can change over time. The used address will be replaced with a
+newly resolved address when the server becomes unreachable (i.e. no valid
+response to last 8 requests), unsynchronised, a falseticker (i.e. does not
+agree with a majority of other sources), or the root distance is too large (the
+limit can be configured by the <<maxdistance,*maxdistance*>> directive). The
+automatic replacement happens at most once per 30 minutes. It can also be
+triggered manually for all sources by the <<chronyc.adoc#refresh,*refresh*>>
+command in *chronyc*.
++
+This directive can be used multiple times to specify multiple servers.
++
+The directive supports the following options:
++
+*minpoll* _poll_:::
+This option specifies the minimum interval between requests sent to the server
+as a power of 2 in seconds. For example, *minpoll 5* would mean that the
+polling interval should not drop below 32 seconds. The default is 6 (64
+seconds), the minimum is -7 (1/128th of a second), and the maximum is 24 (6
+months). Note that intervals shorter than 6 (64 seconds) should generally not
+be used with public servers on the Internet, because it might be considered
+abuse. A sub-second interval will be enabled only when the server is reachable
+and the round-trip delay is shorter than 10 milliseconds, i.e. the server
+should be in a local network.
+*maxpoll* _poll_:::
+This option specifies the maximum interval between requests sent to the server
+as a power of 2 in seconds. For example, *maxpoll 9* indicates that the polling
+interval should stay at or below 9 (512 seconds). The default is 10 (1024
+seconds), the minimum is -7 (1/128th of a second), and the maximum is 24 (6
+months).
+*iburst*:::
+With this option, *chronyd* will start with a burst of 4-8 requests in order to
+make the first update of the clock sooner. It will also repeat the burst every
+time the source is switched from the offline state to online with the
+<<chronyc.adoc#online,*online*>> command in *chronyc*.
+*burst*:::
+With this option, *chronyd* will send a burst of up to 4 requests when it
+cannot get a good measurement from the
+server. The number of requests in the burst is limited by the current polling
+interval to keep the average interval at or above the minimum interval, i.e.
+the current interval needs to be at least two times longer than the minimum
+interval in order to allow a burst with two requests.
+*key* _ID_:::
+The NTP protocol supports a message authentication code (MAC) to prevent
+computers having their system time upset by rogue packets being sent to them.
+The MAC is generated as a function of a key specified in the key file,
+which is specified by the <<keyfile,*keyfile*>> directive.
++
+The *key* option specifies which key (with an ID in the range 1 through 2^32-1)
+should *chronyd* use to authenticate requests sent to the server and verify its
+responses. The server must have the same key for this number configured,
+otherwise no relationship between the computers will be possible.
++
+If the server is running *ntpd* and the output size of the hash function used
+by the key is longer than 160 bits (e.g. SHA256), the *version* option needs to
+be set to 4 for compatibility.
+*nts*:::
+This option enables authentication using the Network Time Security (NTS)
+mechanism. Unlike with the *key* option, the server and client do not need to
+share a key in a key file. NTS has a Key Establishment (NTS-KE) protocol using
+the Transport Layer Security (TLS) protocol to get the keys and cookies
+required by NTS for authentication of NTP packets.
+*certset* _ID_:::
+This option specifies which set of trusted certificates should be used to verify
+the server's certificate when the *nts* option is enabled. Sets of certificates
+can be specified with the <<ntstrustedcerts,*ntstrustedcerts*>> directive. The
+default set is 0, which by default contains certificates of the system's
+default trusted certificate authorities.
+*maxdelay* _delay_:::
+*chronyd* uses the network round-trip delay to the server to determine how
+accurate a particular measurement is likely to be. Long round-trip delays
+indicate that the request, or the response, or both were delayed. If only one
+of the messages was delayed the measurement error is likely to be substantial.
++
+For small variations in the round-trip delay, *chronyd* uses a weighting scheme
+when processing the measurements. However, beyond a certain level of delay the
+measurements are likely to be so corrupted as to be useless. (This is
+particularly so on wireless networks and other slow links, where a long delay
+probably indicates a highly asymmetric delay caused by the response waiting
+behind a lot of packets related to a download of some sort).
++
+If the user knows that round trip delays above a certain level should cause the
+measurement to be ignored, this level can be defined with the *maxdelay*
+option. For example, *maxdelay 0.3* would indicate that measurements with a
+round-trip delay greater than 0.3 seconds should be ignored. The default value
+is 3 seconds and the maximum value is 1000 seconds.
+*maxdelayratio* _ratio_:::
+This option is similar to the *maxdelay* option above. *chronyd* keeps a record
+of the minimum round-trip delay amongst the previous measurements that it has
+buffered. If a measurement has a round-trip delay that is greater than the
+specified ratio times the minimum delay, it will be rejected. By default, this
+test is disabled.
+*maxdelaydevratio* _ratio_:::
+If a measurement has a ratio of the increase in the round-trip delay from the
+minimum delay amongst the previous measurements to the standard deviation of
+the previous measurements that is greater than the specified ratio, it will be
+rejected. The default is 10.0.
+*maxdelayquant* _p_:::
+This option disables the *maxdelaydevratio* test and specifies the maximum
+acceptable delay as a quantile of the round-trip delay instead of a function of
+the minimum delay amongst the buffered measurements. If a measurement has a
+round-trip delay that is greater than a long-term estimate of the _p_-quantile,
+it will be rejected.
++
+The specified _p_ value should be between 0.05 and 0.95. For example,
+*maxdelayquant 0.2* would indicate that only measurements with the lowest 20
+percent of round-trip delays should be accepted. Note that it can take many
+measurements for the estimated quantile to reach the expected value. This
+option is intended for synchronisation in mostly static local networks with
+very short polling intervals and possibly combined with the *filter* option.
+By default, this test is disabled in favour of the *maxdelaydevratio* test.
+*mindelay* _delay_:::
+This option specifies a fixed minimum round-trip delay to be used instead of
+the minimum amongst the previous measurements. This can be useful in networks
+with static configuration to improve the stability of corrections for
+asymmetric jitter, weighting of the measurements, and the *maxdelayratio* and
+*maxdelaydevratio* tests. The value should be set accurately in order to have a
+positive effect on the synchronisation.
+*asymmetry* _ratio_:::
+This option specifies the asymmetry of the network jitter on the path to the
+source, which is used to correct the measured offset according to the delay.
+The asymmetry can be between -0.5 and +0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent from
+the source back. By default, *chronyd* estimates the asymmetry automatically.
+*offset* _offset_:::
+This option specifies a correction (in seconds) which will be applied to
+offsets measured with this source. It's particularly useful to compensate for a
+known asymmetry in network delay or timestamping errors. For example, if
+packets sent to the source were on average delayed by 100 microseconds more
+than packets sent from the source back, the correction would be -0.00005 (-50
+microseconds). The default is 0.0.
+*minsamples* _samples_:::
+Set the minimum number of samples kept for this source. This overrides the
+<<minsamples,*minsamples*>> directive.
+*maxsamples* _samples_:::
+Set the maximum number of samples kept for this source. This overrides the
+<<maxsamples,*maxsamples*>> directive.
+*filter* _polls_:::
+This option enables a median filter to reduce noise in NTP measurements. The
+filter will process samples collected in the specified number of polls
+into a single sample. It is intended to be used with very short polling
+intervals in local networks where it is acceptable to generate a lot of NTP
+traffic.
+*offline*:::
+If the server will not be reachable when *chronyd* is started, the *offline*
+option can be specified. *chronyd* will not try to poll the server until it is
+enabled to do so (by using the <<chronyc.adoc#online,*online*>> command in
+*chronyc*).
+*auto_offline*:::
+With this option, the server will be assumed to have gone offline when sending
+a request fails, e.g. due to a missing route to the network. This option avoids
+the need to run the <<chronyc.adoc#offline,*offline*>> command from *chronyc*
+when disconnecting the network link. (It will still be necessary to use the
+<<chronyc.adoc#online,*online*>> command when the link has been established, to
+enable measurements to start.)
+*prefer*:::
+Prefer this source over sources without the *prefer* option.
+*noselect*:::
+Never select this source. This is particularly useful for monitoring.
+*trust*:::
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+*require*:::
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the *trust* option this might be useful to allow a trusted
+authenticated source to be safely combined with unauthenticated sources in
+order to improve the accuracy of the clock. They can be selected and used for
+synchronisation only if they agree with the trusted and required source.
+*xleave*:::
+This option enables the interleaved mode of NTP. It enables the server to
+respond with more accurate transmit timestamps (e.g. kernel or hardware
+timestamps), which cannot be contained in the transmitted packet itself and
+need to refer to a previous packet instead. This can significantly improve the
+accuracy and stability of the measurements.
++
+The interleaved mode is compatible with servers that support only the basic
+mode. Note that even
+servers that support the interleaved mode might respond in the basic mode as
+the interleaved mode requires the servers to keep some state for each client
+and the state might be dropped when there are too many clients (e.g.
+<<clientloglimit,*clientloglimit*>> is too small), or it might be overwritten
+by other clients that have the same IP address (e.g. computers behind NAT or
+someone sending requests with a spoofed source address).
++
+The *xleave* option can be combined with the *presend* option in order to
+shorten the interval in which the server has to keep the state to be able to
+respond in the interleaved mode.
+*polltarget* _target_:::
+Target number of measurements to use for the regression algorithm which
+*chronyd* will try to maintain by adjusting the polling interval between
+*minpoll* and *maxpoll*. A higher target makes *chronyd* prefer shorter polling
+intervals. The default is 8 and a useful range is from 6 to 60.
+*port* _port_:::
+This option allows the UDP port on which the server understands NTP requests to
+be specified. For normal servers this option should not be required (the
+default is 123, the standard NTP port).
+*ntsport* _port_:::
+This option specifies the TCP port on which the server is listening for NTS-KE
+connections when the *nts* option is enabled. The default is 4460.
+*presend* _poll_:::
+If the timing measurements being made by *chronyd* are the only network data
+passing between two computers, you might find that some measurements are badly
+skewed due to either the client or the server having to do an ARP lookup on the
+other party prior to transmitting a packet. This is more of a problem with long
+sampling intervals, which might be similar in duration to the lifetime of entries
+in the ARP caches of the machines.
++
+In order to avoid this problem, the *presend* option can be used. It takes a
+single integer argument, which is the smallest polling interval for which an
+extra pair of NTP packets will be exchanged between the client and the server
+prior to the actual measurement. For example, with the following option
+included in a *server* directive:
++
+----
+presend 9
+----
++
+when the polling interval is 512 seconds or more, an extra NTP client packet
+will be sent to the server a short time (2 seconds) before making the actual
+measurement.
++
+If the *presend* option is used together with the *xleave* option, *chronyd*
+will send two extra packets instead of one.
+*minstratum* _stratum_:::
+When the synchronisation source is selected from available sources, sources
+with lower stratum are normally slightly preferred. This option can be used to
+increase stratum of the source to the specified minimum, so *chronyd* will
+avoid selecting that source. This is useful with low-stratum sources that are
+known to be unreliable or inaccurate and which should be used only when other
+sources are unreachable.
+*version* _version_:::
+This option sets the NTP version of packets sent to the server. This can be
+useful when the server runs an old NTP implementation that does not respond to
+requests using a newer version. The default version depends on other options.
+If the *extfield* or *xleave* option is used, the default version is 4. If
+those options are not used and the *key* option specifies a key using a hash
+function with output size longer than 160 bits (e.g. SHA256), the default
+version is 3 for compatibility with older *chronyd* servers. In other cases,
+the default version is 4.
+*copy*:::
+This option specifies that the server and client are closely related, their
+configuration does not allow a synchronisation loop to form between them, and
+the client is allowed to assume the reference ID and stratum of the server.
+This is useful when multiple instances of `chronyd` are running on one computer
+(e.g. for security or performance reasons), one primarily operating as a client
+to synchronise the system clock and other instances started with the *-x*
+option to operate as NTP servers for other computers with their NTP clocks
+synchronised to the first instance.
+*extfield* _type_:::
+This option enables an NTPv4 extension field specified by its type as a
+hexadecimal number. It will be included in requests sent to the server and
+processed in received responses if the server supports it. Note that some
+server implementations do not respond to requests containing an unknown
+extension field (*chronyd* as a server responded to such requests since
+version 2.0).
++
+The following extension field can be enabled by this option:
++
+_F323_::::
+This is an experimental extension field for some improvements that were
+proposed for the next version of the NTP protocol (NTPv5). The field contains
+root delay and dispersion in higher resolution and a monotonic receive
+timestamp, which enables a frequency transfer between the server and client. It
+can significantly improve stability of the synchronization. Generally, it
+should be expected to work only between servers and clients running the same
+version of *chronyd*.
+{blank}:::
+
+[[pool]]*pool* _name_ [_option_]...::
+The syntax of this directive is similar to that for the <<server,*server*>>
+directive, except that it is used to specify a pool of NTP servers rather than
+a single NTP server. The pool name is expected to resolve to multiple addresses
+which might change over time.
++
+This directive can be used multiple times to specify multiple pools.
++
+All options valid in the <<server,*server*>> directive can be used in this
+directive too. There is one option specific to the *pool* directive:
++
+*maxsources* _sources_:::
+This option sets the desired number of sources to be used from the pool.
+*chronyd* will repeatedly try to resolve the name until it gets this number of
+sources responding to requests. The default value is 4 and the maximum value is
+16.
++
+An example of the *pool* directive is
++
+----
+pool pool.ntp.org iburst maxsources 3
+----
+
+[[peer]]*peer* _hostname_ [_option_]...::
+The syntax of this directive is identical to that for the <<server,*server*>>
+directive, except that it specifies a symmetric association with an NTP peer
+instead of a client/server association with an NTP server. A single symmetric
+association allows the peers to be both servers and clients to each other. This
+is mainly useful when the NTP implementation of the peer (e.g. *ntpd*) supports
+ephemeral symmetric associations and does not need to be configured with an
+address of this host. *chronyd* does not support ephemeral associations.
++
+This directive can be used multiple times to specify multiple peers.
++
+The following options of the *server* directive do not work in the *peer*
+directive: *iburst*, *burst*, *nts*, *presend*, *copy*.
++
+When using the *xleave* option, both peers must support and have enabled the
+interleaved mode, otherwise the synchronisation will work in one direction
+only.
+When a key is specified by the *key* option to enable authentication, both
+peers must use the same key and the same key number.
++
+Note that the symmetric mode is less secure than the client/server mode. A
+denial-of-service attack is possible on unauthenticated symmetric associations,
+i.e. when the peer was specified without the *key* option. An attacker who does
+not see network traffic between two hosts, but knows that they are peering with
+each other, can periodically send them unauthenticated packets with spoofed
+source addresses in order to disrupt their NTP state and prevent them from
+synchronising to each other. When the association is authenticated, an attacker
+who does see the network traffic, but cannot prevent the packets from reaching
+the other host, can still disrupt the state by replaying old packets. The
+attacker has effectively the same power as a man-in-the-middle attacker. A
+partial protection against this attack is implemented in *chronyd*, which can
+protect the peers if they are using the same polling interval and they never
+sent an authenticated packet with a timestamp from future, but it should not be
+relied on as it is difficult to ensure the conditions are met. If two hosts
+should be able to synchronise to each other in both directions, it is
+recommended to use two separate client/server associations (specified by the
+<<server,*server*>> directive on both hosts) instead.
+
+[[initstepslew]]*initstepslew* _step-threshold_ [_hostname_]...::
+(This directive is deprecated in favour of the <<makestep,*makestep*>>
+directive.)
++
+The purpose of the *initstepslew* directive is to allow *chronyd* to make a
+rapid measurement of the system clock error at boot time, and to correct the
+system clock by stepping before normal operation begins. Since this would
+normally be performed only at an appropriate point in the system boot sequence,
+no other software should be adversely affected by the step.
++
+If the correction required is less than a specified threshold, a slew is used
+instead. This makes it safer to restart *chronyd* whilst the system is in
+normal operation.
++
+The *initstepslew* directive takes a threshold and a list of NTP servers as
+arguments. Each of the servers is rapidly polled several times, and a majority
+voting mechanism used to find the most likely range of system clock error that
+is present. A step or slew is applied to the system clock to correct this
+error. *chronyd* then enters its normal operating mode.
++
+An example of the use of the directive is:
++
+----
+initstepslew 30 foo.example.net bar.example.net baz.example.net
+----
++
+where 3 NTP servers are used to make the measurement. The _30_ indicates that
+if the system's error is found to be 30 seconds or less, a slew will be used to
+correct it; if the error is above 30 seconds, a step will be used.
++
+The *initstepslew* directive can also be used in an isolated LAN environment,
+where the clocks are set manually. The most stable computer is chosen as the
+primary server and the other computers are its clients. If each of the clients
+is configured with the <<local,*local*>> directive, the server can be set up
+with an *initstepslew* directive which references some or all of the clients.
+Then, if the server machine has to be rebooted, the clients can be relied on to
+act analogously to a flywheel and preserve the time for a short period while
+the server completes its reboot.
++
+The *initstepslew* directive is functionally similar to a combination of the
+<<makestep,*makestep*>> and <<server,*server*>> directives with the *iburst*
+option. The main difference is that the *initstepslew* servers are used only
+before normal operation begins and that the foreground *chronyd* process waits
+for *initstepslew* to finish before exiting. This prevent programs started in
+the boot sequence after *chronyd* from reading the clock before it has been
+stepped. With the *makestep* directive, the
+<<chronyc.adoc#waitsync,*waitsync*>> command of *chronyc* can be used instead.
+
+[[refclock]]*refclock* _driver_ _parameter_[:__option__]... [_option_]...::
+The *refclock* directive specifies a hardware reference clock to be used as a
+time source. It has two mandatory parameters, a driver name and a
+driver-specific parameter. The two parameters are followed by zero or more
+refclock options. Some drivers have special options, which can be appended to
+the driver-specific parameter using the *:* character.
++
+This directive can be used multiple times to specify multiple reference clocks.
++
+There are four drivers included in *chronyd*:
++
+*PPS*:::
+Driver for the kernel PPS (pulse per second) API. The parameter is the path to
+the PPS device (typically _/dev/pps?_). As PPS refclocks do not supply full
+time, another time source (e.g. NTP server or non-PPS refclock) is needed to
+complete samples from the PPS refclock. An alternative is to enable the
+<<local,*local*>> directive to allow synchronisation with some unknown but
+constant offset. The driver supports the following option:
++
+*clear*::::
+By default, the PPS refclock uses assert events (rising edge) for
+synchronisation. With this option, it will use clear events (falling edge)
+instead.
++
+{blank}:::
+Examples:
++
+----
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SHM 0 offset 0.5 delay 0.2 refid NMEA noselect
+refclock PPS /dev/pps1:clear refid GPS2
+----
++
+*SHM*:::
+NTP shared memory driver. This driver uses a shared memory segment to receive
+samples from another process (e.g. *gpsd*). The parameter is the number of the
+shared memory segment, typically a small number like 0, 1, 2, or 3. The driver
+supports the following option:
++
+*perm*=_mode_::::
+This option specifies the permissions of the shared memory segment created by
+*chronyd*. They are specified as a numeric mode. The default value is 0600
+(read-write access for owner only).
+{blank}:::
++
+Examples:
++
+----
+refclock SHM 0 poll 3 refid GPS1
+refclock SHM 1:perm=0644 refid GPS2
+----
++
+*SOCK*:::
+Unix domain socket driver. It is similar to the SHM driver, but samples are
+received from a Unix domain socket instead of shared memory and the messages
+have a different format. The parameter is the path to the socket, which
+*chronyd* creates on start. An advantage over the SHM driver is that SOCK does
+not require polling and it can receive PPS samples with incomplete time. The
+format of the messages is described in the _refclock_sock.c_ file in the chrony
+source code.
++
+An application which supports the SOCK protocol is the *gpsd* daemon. The path
+where *gpsd* expects the socket to be created is described in the *gpsd(8)* man
+page. For example:
++
+----
+refclock SOCK /var/run/chrony.ttyS0.sock
+----
++
+*PHC*:::
+PTP hardware clock (PHC) driver. The parameter is the path to the device of
+the PTP clock which should be used as a time source. If the clock is kept in
+TAI instead of UTC (e.g. it is synchronised by a PTP daemon), the current
+UTC-TAI offset needs to be specified by the *offset* option. Alternatively, the
+*pps* refclock option can be enabled to treat the PHC as a PPS refclock, using
+only the sub-second offset for synchronisation. The driver supports the
+following options:
++
+*nocrossts*::::
+This option disables use of precise cross timestamping.
+*extpps*::::
+This option enables a PPS mode in which the PTP clock is timestamping pulses
+of an external PPS signal connected to the clock. The clock does not need to be
+synchronised, but another time source is needed to complete the PPS samples.
+Note that some PTP clocks cannot be configured to timestamp only assert or
+clear events, and it is necessary to use the *width* option to filter wrong
+PPS samples.
+*pin*=_index_::::
+This option specifies the index of the pin which should be enabled for the
+PPS timestamping. If the PHC does not have configurable pins (i.e. the channel
+function is fixed), the index needs to be set to -1 to disable the pin
+configuration. The default value is 0.
+*channel*=_index_::::
+This option specifies the index of the channel for the PPS mode. The default
+value is 0.
+*clear*::::
+This option enables timestamping of clear events (falling edge) instead of
+assert events (rising edge) in the PPS mode. This may not work with some
+clocks.
+{blank}:::
++
+Examples:
++
+----
+refclock PHC /dev/ptp0 poll 0 dpoll -2 offset -37
+refclock PHC /dev/ptp1:nocrossts poll 3 pps
+refclock PHC /dev/ptp2:extpps:pin=1 width 0.2 poll 2
+----
++
+{blank}::
+The *refclock* directive supports the following options:
++
+*poll* _poll_:::
+Timestamps produced by refclock drivers are not used immediately, but they are
+stored and processed by a median filter in the polling interval specified by
+this option. This is defined as a power of 2 and can be negative to specify a
+sub-second interval. The default is 4 (16 seconds). A shorter interval allows
+*chronyd* to react faster to changes in the frequency of the system clock, but
+it might have a negative effect on its accuracy if the samples have a lot of
+jitter.
+*dpoll* _dpoll_:::
+Some drivers do not listen for external events and try to produce samples in
+their own polling interval. This is defined as a power of 2 and can be negative
+to specify a sub-second interval. The default is 0 (1 second).
+*refid* _refid_:::
+This option is used to specify the reference ID of the refclock, as up to four
+ASCII characters. The default reference ID is composed from the first three
+characters of the driver name and the number of the refclock. Each refclock
+must have a unique reference ID.
+*lock* _refid_:::
+This option can be used to lock a PPS refclock to another refclock, which is
+specified by its reference ID. In this mode received PPS samples are paired
+directly with raw samples from the specified refclock.
+*rate* _rate_:::
+This option sets the rate of the pulses in the PPS signal (in Hz). This option
+controls how the pulses will be completed with real time. To actually receive
+more than one pulse per second, a negative *dpoll* has to be specified (-3 for
+a 5Hz signal). The default is 1.
+*maxlockage* _pulses_:::
+This option specifies in number of pulses how old can be samples from the
+refclock specified by the *lock* option to be paired with the pulses.
+Increasing this value is useful when the samples are produced at a lower rate
+than the pulses. The default is 2.
+*width* _width_:::
+This option specifies the width of the pulses (in seconds). It is used to
+filter PPS samples when the driver provides samples for both rising and falling
+edges. Note that it reduces the maximum allowed error of the time source which
+completes the PPS samples. If the duty cycle is configurable, 50% should be
+preferred in order to maximise the allowed error.
+*pps*:::
+This options forces *chronyd* to treat any refclock (e.g. SHM or PHC) as a PPS
+refclock. This can be useful when the refclock provides time with a variable
+offset of a whole number of seconds (e.g. it uses TAI instead of UTC). Another
+time source is needed to complete samples from the refclock.
+*offset* _offset_:::
+This option can be used to compensate for a constant error. The specified
+offset (in seconds) is applied to all samples produced by the reference clock.
+The default is 0.0.
+*delay* _delay_:::
+This option sets the NTP delay of the source (in seconds). Half of this value
+is included in the maximum assumed error which is used in the source selection
+algorithm. Increasing the delay is useful to avoid having no majority in the
+source selection or to make it prefer other sources. The default is 1e-9 (1
+nanosecond).
+*stratum* _stratum_:::
+This option sets the NTP stratum of the refclock. This can be useful when the
+refclock provides time with a stratum other than 0. The default is 0.
+*precision* _precision_:::
+This option sets the precision of the reference clock (in seconds). The default
+value is the estimated precision of the system clock.
+*maxdispersion* _dispersion_:::
+Maximum allowed dispersion for filtered samples (in seconds). Samples with
+larger estimated dispersion are ignored. By default, this limit is disabled.
+*filter* _samples_:::
+This option sets the length of the median filter which is used to reduce the
+noise in the measurements. With each poll about 40 percent of the stored
+samples are discarded and one final sample is calculated as an average of the
+remaining samples. If the length is 4 or more, at least 4 samples have to be
+collected between polls. For lengths below 4, the filter has to be full. The
+default is 64.
+*prefer*:::
+Prefer this source over sources without the prefer option.
+*noselect*:::
+Never select this source. This is useful for monitoring or with sources which
+are not very accurate, but are locked with a PPS refclock.
+*trust*:::
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+*require*:::
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the *trust* option this can be useful to allow a trusted,
+but not very precise, reference clock to be safely combined with
+unauthenticated NTP sources in order to improve the accuracy of the clock. They
+can be selected and used for synchronisation only if they agree with the
+trusted and required source.
+*tai*:::
+This option indicates that the reference clock keeps time in TAI instead of UTC
+and that *chronyd* should correct its offset by the current TAI-UTC offset. The
+<<leapsectz,*leapsectz*>> directive must be used with this option and the
+database must be kept up to date in order for this correction to work as
+expected. This option does not make sense with PPS refclocks.
+*local*:::
+This option specifies that the reference clock is an unsynchronised clock which
+is more stable than the system clock (e.g. TCXO, OCXO, or atomic clock) and
+it should be used as a local standard to stabilise the system clock. The
+refclock will bypass the source selection. There should be at most one refclock
+specified with this option and it should have the shortest polling interval
+among all configured sources.
+*minsamples* _samples_:::
+Set the minimum number of samples kept for this source. This overrides the
+<<minsamples,*minsamples*>> directive.
+*maxsamples* _samples_:::
+Set the maximum number of samples kept for this source. This overrides the
+<<maxsamples,*maxsamples*>> directive.
+
+[[manual]]*manual*::
+The *manual* directive enables support at run-time for the
+<<chronyc.adoc#settime,*settime*>> command in *chronyc*. If no *manual*
+directive is included, any attempt to use the *settime* command in *chronyc*
+will be met with an error message.
++
+Note that the *settime* command can be enabled at run-time using
+the <<chronyc.adoc#manual,*manual*>> command in *chronyc*. (The idea of the two
+commands is that the *manual* command controls the manual clock driver's
+behaviour, whereas the *settime* command allows samples of manually entered
+time to be provided.)
+
+[[acquisitionport]]*acquisitionport* _port_::
+By default, *chronyd* as an NTP client opens a new socket for each request with
+the source port chosen randomly by the operating system. The *acquisitionport*
+directive can be used to specify the source port and use only one socket (per
+IPv4 or IPv6 address family) for all configured servers. This can be useful for
+getting through some firewalls. It should not be used if not necessary as there
+is a small impact on security of the client. If set to 0, the source port of
+the permanent socket will be chosen randomly by the operating system.
++
+It can be set to the same port as is used by the NTP server (which can be
+configured with the <<port,*port*>> directive) to use only one socket for all
+NTP packets.
++
+An example of the *acquisitionport* directive is:
++
+----
+acquisitionport 1123
+----
++
+This would change the source port used for client requests to UDP port 1123.
+You could then persuade the firewall administrator to open that port.
+
+[[bindacqaddress]]*bindacqaddress* _address_::
+The *bindacqaddress* directive specifies a local IP address to which
+*chronyd* will bind its NTP and NTS-KE client sockets. The syntax is similar to
+the <<bindaddress,*bindaddress*>> and <<bindcmdaddress,*bindcmdaddress*>>
+directives.
++
+For each of the IPv4 and IPv6 protocols, only one *bindacqaddress* directive
+can be specified.
+
+[[bindacqdevice]]*bindacqdevice* _interface_::
+The *bindacqdevice* directive binds the client sockets to a network device
+specified by the interface name. This can be useful when the local address is
+dynamic, or to enable an NTP source specified with a link-local IPv6 address.
+This directive can specify only one interface and it is supported on Linux
+only.
++
+An example of the directive is:
++
+----
+bindacqdevice eth0
+----
+
+[[dscp]]*dscp* _point_::
+The *dscp* directive sets the Differentiated Services Code Point (DSCP) in
+transmitted NTP packets to the specified value. It can improve stability of NTP
+measurements in local networks where switches or routers are configured to
+prioritise forwarding of packets with specific DSCP values. The default value
+is 0 and the maximum value is 63.
++
+An example of the directive (setting the Expedited Forwarding class) is:
++
+----
+dscp 46
+----
+
+[[dumpdir]]*dumpdir* _directory_::
+To compute the rate of gain or loss of time, *chronyd* has to store a
+measurement history for each of the time sources it uses.
++
+All supported systems, with the exception of macOS 10.12 and earlier, have
+operating system support for setting the rate of gain or loss to compensate for
+known errors.
+(On macOS 10.12 and earlier, *chronyd* must simulate such a capability by
+periodically slewing the system clock forwards or backwards by a suitable amount
+to compensate for the error built up since the previous slew.)
++
+For such systems, it is possible to save the measurement history across
+restarts of *chronyd* (assuming no changes are made to the system clock
+behaviour whilst it is not running). The *dumpdir* directive defines the
+directory where the measurement histories are saved when *chronyd* exits,
+or the <<chronyc.adoc#dump,*dump*>> command in *chronyc* is issued.
++
+If the directory does not exist, it will be created automatically.
++
+The *-r* option of *chronyd* enables loading of the dump files on start. All
+dump files found in the directory will be removed after start, even if the *-r*
+option is not present.
++
+An example of the directive is:
++
+----
+dumpdir @CHRONYRUNDIR@
+----
++
+A source whose IP address is _1.2.3.4_ would have its measurement history saved
+in the file _@CHRONYRUNDIR@/1.2.3.4.dat_. History of reference clocks is saved
+to files named by their reference ID in form of _refid:XXXXXXXX.dat_.
+
+[[maxsamples]]*maxsamples* _samples_::
+The *maxsamples* directive sets the default maximum number of samples that
+*chronyd* should keep for each source. This setting can be overridden for
+individual sources in the <<server,*server*>> and <<refclock,*refclock*>>
+directives. The default value is 0, which disables the configurable limit. The
+useful range is 4 to 64.
++
+As a special case, setting *maxsamples* to 1 disables frequency tracking in
+order to make the sources immediately selectable with only one sample. This can
+be useful when *chronyd* is started with the *-q* or *-Q* option.
+
+[[minsamples]]*minsamples* _samples_::
+The *minsamples* directive sets the default minimum number of samples that
+*chronyd* should keep for each source. This setting can be overridden for
+individual sources in the <<server,*server*>> and <<refclock,*refclock*>>
+directives. The default value is 6. The useful range is 4 to 64.
++
+Forcing *chronyd* to keep more samples than it would normally keep reduces
+noise in the estimated frequency and offset, but slows down the response to
+changes in the frequency and offset of the clock. The offsets in the
+<<chronyc.adoc#tracking,*tracking*>> and
+<<chronyc.adoc#sourcestats,*sourcestats*>> reports (and the _tracking.log_ and
+_statistics.log_ files) may be smaller than the actual offsets.
+
+[[ntsdumpdir1]]*ntsdumpdir* _directory_::
+This directive specifies a directory for the client to save NTS cookies it
+received from the server in order to avoid making an NTS-KE request when
+*chronyd* is started again. The cookies are saved separately for each NTP
+source in files named by the IP address of the NTS-KE server (e.g.
+_1.2.3.4.nts_). By default, the client does not save the cookies.
++
+If the directory does not exist, it will be created automatically.
++
+An example of the directive is:
++
+----
+ntsdumpdir @CHRONYVARDIR@
+----
++
+This directory is used also by the <<ntsdumpdir2,NTS server>> to save keys.
+
+[[ntsrefresh]]*ntsrefresh* _interval_::
+This directive specifies the maximum interval between NTS-KE handshakes (in
+seconds) in order to refresh the keys authenticating NTP packets. The default
+value is 2419200 (4 weeks) and the maximum value is 2^31-1 (68 years).
+
+[[ntstrustedcerts]]*ntstrustedcerts* [_set-ID_] _file_|_directory_::
+This directive specifies a file or directory containing certificates (in the
+PEM format) of trusted certificate authorities (CA) which can be used to
+verify certificates of NTS servers.
++
+The optional _set-ID_ argument is a number in the range 0 through 2^32-1, which
+selects the set of certificates where certificates from the specified file
+or directory are added. The default ID is 0, which is a set containing the
+system's default trusted CAs (unless the *nosystemcert* directive is present).
+All other sets are empty by default. A set of certificates can be selected for
+verification of an NTS server by the *certset* option in the *server* or *pool*
+directive.
++
+This directive can be used multiple times to specify one or more sets of
+trusted certificates, each containing certificates from one or more files
+and/or directories.
++
+It is not necessary to restart *chronyd* in order to reload the certificates if
+they change (e.g. after a renewal).
++
+An example is:
++
+----
+ntstrustedcerts /etc/pki/nts/foo.crt
+ntstrustedcerts 1 /etc/pki/nts/bar.crt
+ntstrustedcerts 1 /etc/pki/nts/baz.crt
+ntstrustedcerts 2 /etc/pki/nts/qux.crt
+----
+
+[[nosystemcert]]*nosystemcert*::
+This directive disables the system's default trusted CAs. Only certificates
+specified by the *ntstrustedcerts* directive will be trusted.
+
+[[nocerttimecheck]]*nocerttimecheck* _limit_::
+This directive disables the checks of the activation and expiration times of
+certificates for the specified number of clock updates. It allows the NTS
+authentication mechanism to be used on computers which start with wrong time
+(e.g. due to not having an RTC or backup battery). Disabling the time checks
+has important security implications and should be used only as a last resort,
+preferably with a minimal number of trusted certificates. The default value is
+0, which means the time checks are always enabled.
++
+An example of the directive is:
++
+----
+nocerttimecheck 1
+----
++
+This would disable the time checks until the clock is updated for the first
+time, assuming the first update corrects the clock and later checks can work
+with correct time.
+
+=== Source selection
+
+[[authselectmode]]*authselectmode* _mode_::
+NTP sources can be specified with the *key* or *nts* option to enable
+authentication to limit the impact of man-in-the-middle attacks. The
+attackers can drop or delay NTP packets (up to the *maxdelay* and
+<<maxdistance,*maxdistance*>> limits), but they cannot modify the timestamps
+contained in the packets. The attack can cause only a limited slew or step, and
+also cause the clock to run faster or slower than real time (up to double of
+the <<maxdrift,*maxdrift*>> limit).
++
+When authentication is enabled for an NTP source, it is important to disable
+unauthenticated NTP sources which could be exploited in the attack, e.g. if
+they are not reachable only over a trusted network. Alternatively, the source
+selection can be configured with the *require* and *trust* options to
+synchronise to the unauthenticated sources only if they agree with the
+authenticated sources and might have a positive impact on the accuracy of the
+clock. Note that in this case the impact of the attack is higher. The attackers
+cannot cause an arbitrarily large step or slew, but they have more control over
+the frequency of the clock and can cause *chronyd* to report false information,
+e.g. a significantly smaller root delay and dispersion.
++
+This directive determines the default selection options for authenticated and
+unauthenticated sources in order to simplify the configuration with the
+configuration file and *chronyc* commands. It sets a policy for authentication.
++
+Sources specified with the *noselect* option are ignored (not counted as either
+authenticated or unauthenticated), and they always have only the selection
+options specified in the configuration.
++
+There are four modes:
++
+*require*:::
+Authentication is strictly required for NTP sources in this mode. If any
+unauthenticated NTP sources are specified, they will automatically get the
+*noselect* option to prevent them from being selected for synchronisation.
+*prefer*:::
+In this mode, authentication is optional and preferred. If it is enabled for at
+least one NTP source, all unauthenticated NTP sources will get the *noselect*
+option.
+*mix*:::
+In this mode, authentication is optional and synchronisation to a mix of
+authenticated and unauthenticated NTP sources is allowed. If both authenticated
+and unauthenticated NTP sources are specified, all authenticated NTP sources
+and reference clocks will get the *require* and *trust* options to prevent
+synchronisation to unauthenticated NTP sources if they do not agree with a
+majority of the authenticated sources and reference clocks. This is the default
+mode.
+*ignore*:::
+In this mode, authentication is ignored in the source selection. All sources
+will have only the selection options that were specified in the configuration
+file, or *chronyc* command. This was the behaviour of *chronyd* in versions
+before 4.0.
+{blank}::
++
+As an example, the following configuration using the default *mix* mode:
++
+----
+server foo.example.net nts
+server bar.example.net nts
+server baz.example.net
+refclock SHM 0
+----
++
+is equivalent to the following configuration using the *ignore* mode:
++
+----
+authselectmode ignore
+server foo.example.net nts require trust
+server bar.example.net nts require trust
+server baz.example.net
+refclock SHM 0 require trust
+----
+
+[[combinelimit]]*combinelimit* _limit_::
+When *chronyd* has multiple sources available for synchronisation, it has to
+select one source as the synchronisation source. The measured offsets and
+frequencies of the system clock relative to the other sources, however, can be
+combined with the selected source to improve the accuracy of the system clock.
++
+The *combinelimit* directive limits which sources are included in the combining
+algorithm. Their synchronisation distance has to be shorter than the distance
+of the selected source multiplied by the value of the limit. Also, their
+measured frequencies have to be close to the frequency of the selected source.
+If the selected source was specified with the *prefer* option, it can be
+combined only with other sources specified with this option.
++
+By default, the limit is 3. Setting the limit to 0 effectively disables the
+source combining algorithm and only the selected source will be used to control
+the system clock.
+
+[[maxdistance]]*maxdistance* _distance_::
+The *maxdistance* directive sets the maximum root distance of a source to be
+acceptable for synchronisation of the clock. Sources that have a distance
+larger than the specified distance will be rejected. The distance estimates the
+maximum error of the source. It includes the root dispersion and half of the
+root delay (round-trip time) accumulated on the path to the primary source.
++
+By default, the maximum root distance is 3 seconds.
++
+Setting *maxdistance* to a larger value can be useful to allow synchronisation
+with a server that only has a very infrequent connection to its sources and can
+accumulate a large dispersion between updates of its clock.
+
+[[maxjitter]]*maxjitter* _jitter_::
+The *maxjitter* directive sets the maximum allowed jitter of the sources to not
+be rejected by the source selection algorithm. This prevents synchronisation
+with sources that have a small root distance, but their time is too variable.
++
+By default, the maximum jitter is 1 second.
+
+[[minsources]]*minsources* _sources_::
+The *minsources* directive sets the minimum number of sources that need to be
+considered as selectable in the source selection algorithm before the local
+clock is updated. The default value is 1.
++
+Setting this option to a larger number can be used to improve the reliability.
+More sources will have to agree with each other and the clock will not be
+updated when only one source (which could be serving incorrect time) is
+reachable.
+
+[[reselectdist]]*reselectdist* _distance_::
+When *chronyd* selects a synchronisation source from available sources, it
+will prefer the one with the shortest synchronisation distance. However, to
+avoid frequent reselecting when there are sources with similar distance, a
+fixed distance is added to the distance for sources that are currently not
+selected. This can be set with the *reselectdist* directive. By default, the
+distance is 100 microseconds.
+
+[[stratumweight]]*stratumweight* _distance_::
+The *stratumweight* directive sets how much distance should be added per
+stratum to the synchronisation distance when *chronyd* selects the
+synchronisation source from available sources.
++
+By default, the weight is 0.001 seconds. This means that the stratum of the sources
+in the selection process matters only when the differences between the
+distances are in milliseconds.
+
+=== System clock
+
+[[clockprecision]]*clockprecision* _precision_::
+The *clockprecision* directive specifies the precision of the system clock (in
+seconds). It is used by *chronyd* to estimate the minimum noise in NTP
+measurements and randomise low-order bits of timestamps in NTP responses. By
+default, the precision is measured on start as the minimum time to read the
+clock.
++
+The measured value works well in most cases. However, it generally
+overestimates the precision and it can be sensitive to the CPU speed, which can
+change over time to save power. In some cases with a high-precision clocksource
+(e.g. the Time Stamp Counter of the CPU) and hardware timestamping, setting the
+precision on the server to a smaller value can improve stability of clients'
+NTP measurements. The server's precision is reported on clients by the
+<<chronyc.adoc#ntpdata,*ntpdata*>> command.
++
+An example setting the precision to 8 nanoseconds is:
++
+----
+clockprecision 8e-9
+----
+
+[[corrtimeratio]]*corrtimeratio* _ratio_::
+When *chronyd* is slewing the system clock to correct an offset, the rate at
+which it is slewing adds to the frequency error of the clock. On all supported
+systems, with the exception of macOS 12 and earlier, this rate can be
+controlled.
++
+The *corrtimeratio* directive sets the ratio between the duration in which the
+clock is slewed for an average correction according to the source history and
+the interval in which the corrections are done (usually the NTP polling
+interval). Corrections larger than the average take less time and smaller
+corrections take more time, the amount of the correction and the correction
+time are inversely proportional.
++
+Increasing *corrtimeratio* improves the overall frequency error of the system
+clock, but increases the overall time error as the corrections take longer.
++
+By default, the ratio is set to 3, the time accuracy of the clock is preferred
+over its frequency accuracy.
++
+The maximum allowed slew rate can be set by the <<maxslewrate,*maxslewrate*>>
+directive. The current remaining correction is shown in the
+<<chronyc.adoc#tracking,*tracking*>> report as the *System time* value.
+
+[[driftfile]]*driftfile* _file_::
+One of the main activities of the *chronyd* program is to work out the rate at
+which the system clock gains or loses time relative to real time.
++
+Whenever *chronyd* computes a new value of the gain or loss rate, it is desirable
+to record it somewhere. This allows *chronyd* to begin compensating the system
+clock at that rate whenever it is restarted, even before it has had a chance to
+obtain an equally good estimate of the rate during the new run. (This process
+can take many minutes, at least.)
++
+The *driftfile* directive allows a file to be specified into which *chronyd*
+can store the rate information. Two parameters are recorded in the file. The
+first is the rate at which the system clock gains or loses time, expressed in
+parts per million, with gains positive. Therefore, a value of 100.0 indicates
+that when the system clock has advanced by a second, it has gained 100
+microseconds in reality (so the true time has only advanced by 999900
+microseconds). The second is an estimate of the error bound around the first
+value in which the true rate actually lies.
++
+An example of the driftfile directive is:
++
+----
+driftfile @CHRONYVARDIR@/drift
+----
+
+[[fallbackdrift]]*fallbackdrift* _min-interval_ _max-interval_::
+Fallback drifts are long-term averages of the system clock drift calculated
+over exponentially increasing intervals. They are used to avoid quickly
+drifting away from true time when the clock was not updated for a longer period
+of time and there was a short-term deviation in the drift before the updates
+stopped.
++
+The directive specifies the minimum and maximum interval since the last clock
+update to switch between fallback drifts. They are defined as a power of 2 (in
+seconds). The syntax is as follows:
++
+----
+fallbackdrift 16 19
+----
++
+In this example, the minimum interval is 16 (18 hours) and the maximum interval is
+19 (6 days). The system clock frequency will be set to the first fallback 18
+hours after last clock update, to the second after 36 hours, and so on. This
+might be a good setting to cover frequency changes due to daily and weekly
+temperature fluctuations. When the frequency is set to a fallback, the state of
+the clock will change to '`Not synchronised`'.
++
+By default (or if the specified maximum or minimum is 0), no fallbacks are used
+and the clock frequency changes only with new measurements from NTP sources,
+reference clocks, or manual input.
+
+[[leapsecmode]]*leapsecmode* _mode_::
+A leap second is an adjustment that is occasionally applied to UTC to keep it
+close to the mean solar time. When a leap second is inserted, the last day of
+June or December has an extra second 23:59:60.
++
+For computer clocks that is a problem. The Unix time is defined as number of
+seconds since 00:00:00 UTC on 1 January 1970 without leap seconds. The system
+clock cannot have time 23:59:60, every minute has 60 seconds and every day has
+86400 seconds by definition. The inserted leap second is skipped and the clock
+is suddenly ahead of UTC by one second. The *leapsecmode* directive selects how
+that error is corrected. There are four options:
++
+*system*:::
+When inserting a leap second, the kernel steps the system clock backwards by
+one second when the clock gets to 00:00:00 UTC. When deleting a leap second, it
+steps forward by one second when the clock gets to 23:59:59 UTC. This is the
+default mode when the system driver supports leap seconds (i.e. all supported
+systems with the exception of macOS 12 and earlier).
+*step*:::
+This is similar to the *system* mode, except the clock is stepped by
+*chronyd* instead of the kernel. It can be useful to avoid bugs in the kernel
+code that would be executed in the *system* mode. This is the default mode
+when the system driver does not support leap seconds.
+*slew*:::
+The clock is corrected by slewing started at 00:00:00 UTC when a leap second
+is inserted or 23:59:59 UTC when a leap second is deleted. This might be
+preferred over the *system* and *step* modes when applications running on the
+system are sensitive to jumps in the system time and it is acceptable that the
+clock will be off for a longer time. On Linux with the default
+<<maxslewrate,*maxslewrate*>> value the correction takes 12 seconds.
+*ignore*:::
+No correction is applied to the clock for the leap second. The clock will be
+corrected later in normal operation when new measurements are made and the
+estimated offset includes the one second error. This option is particularly
+useful when multiple *chronyd* instances are running on the system, one
+controlling the system clock and others started with the *-x* option, which
+should rely on the first instance to correct the system clock and ignore it for
+the correction of their own NTP clock running on top of the system clock.
+{blank}::
++
+When serving time to NTP clients that cannot be configured to correct their
+clocks for a leap second by slewing, or to clients that would correct at
+slightly different rates when it is necessary to keep them close together, the
+*slew* mode can be combined with the <<smoothtime,*smoothtime*>> directive to
+enable a server leap smear.
++
+When smearing a leap second, the leap status is suppressed on the server and
+the served time is corrected slowly by slewing instead of stepping. The clients
+do not need any special configuration as they do not know there is any leap
+second and they follow the server time which eventually brings them back to
+UTC. Care must be taken to ensure they use only NTP servers which smear the
+leap second in exactly the same way for synchronisation.
++
+This feature must be used carefully, because the server is intentionally not
+serving its best estimate of the true time.
++
+A recommended configuration to enable a server leap smear is:
++
+----
+leapsecmode slew
+maxslewrate 1000
+smoothtime 400 0.001024 leaponly
+----
++
+The first directive is necessary to disable the clock step which would reset
+the smoothing process. The second directive limits the slewing rate of the
+local clock to 1000 ppm, which improves the stability of the smoothing process
+when the local correction starts and ends. The third directive enables the
+server time smoothing process. It will start when the clock gets to 00:00:00
+UTC and it will take 62500 seconds (about 17.36 hours) to finish. The frequency
+offset will be changing by 0.001024 ppm per second and will reach a maximum of
+32 ppm in 31250 seconds. The *leaponly* option makes the duration of the leap
+smear constant and allows the clients to safely synchronise with multiple
+identically configured leap smearing servers.
++
+The duration of the leap smear can be calculated from the specified wander as
++
+----
+duration = sqrt(4 / wander)
+----
+
+[[leapsectz]]*leapsectz* _timezone_::
+This directive specifies a timezone in the system timezone database which
+*chronyd* can use to determine when will the next leap second occur and what is
+the current offset between TAI and UTC. It will periodically check if 23:59:59
+and 23:59:60 are valid times in the timezone. This normally works with the
+_right/UTC_ timezone.
++
+When a leap second is announced, the timezone needs to be updated at least 12
+hours before the leap second. It is not necessary to restart *chronyd*.
++
+This directive is useful with reference clocks and other time sources which do
+not announce leap seconds, or announce them too late for an NTP server to
+forward them to its own clients. Clients of leap smearing servers must not
+use this directive.
++
+It is also useful when the system clock is required to have correct TAI-UTC
+offset. Note that the offset is set only when leap seconds are handled by the
+kernel, i.e. <<leapsecmode,*leapsecmode*>> is set to *system*.
++
+The specified timezone is not used as an exclusive source of information about
+leap seconds. If a majority of time sources announce on the last day of June or
+December that a leap second should be inserted or deleted, it will be accepted
+even if it is not included in the timezone.
++
+An example of the directive is:
++
+----
+leapsectz right/UTC
+----
++
+The following shell command verifies that the timezone contains leap seconds
+and can be used with this directive:
++
+----
+$ TZ=right/UTC date -d 'Dec 31 2008 23:59:60'
+Wed Dec 31 23:59:60 UTC 2008
+----
+
+[[makestep]]*makestep* _threshold_ _limit_::
+Normally *chronyd* will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+e.g. when *chronyd* is initially started, the system clock might be so far
+adrift that this slewing process would take a very long time to correct the
+system clock.
++
+This directive forces *chronyd* to step the system clock if the adjustment is
+larger than a threshold value, but only if there were no more clock updates
+since *chronyd* was started than the specified limit. A negative value disables
+the limit.
++
+On most systems it is desirable to step the system clock only on boot, before
+starting programs that rely on time advancing monotonically forwards.
++
+An example of the use of this directive is:
++
+----
+makestep 0.1 3
+----
++
+This would step the system clock if the adjustment is larger than 0.1 seconds, but
+only in the first three clock updates.
+
+[[maxchange]]*maxchange* _offset_ _start_ _ignore_::
+This directive sets the maximum offset to be accepted on a clock update. The
+offset is measured relative to the current estimate of the true time, which is
+different from the system time if a previous slew did not finish.
++
+The check is enabled after the specified number of clock updates to allow a
+large initial offset to be corrected on start. Offsets larger than the
+specified maximum will be ignored for the specified number of times. Another
+large offset will cause *chronyd* to give up and exit. A negative value
+can be used to disable the limit to ignore all large offsets. A syslog message
+will be generated when an offset is ignored or it causes the exit.
++
+An example of the use of this directive is:
++
+----
+maxchange 1000 1 2
+----
++
+After the first clock update, *chronyd* will check the offset on every clock
+update, it will ignore two adjustments larger than 1000 seconds and exit on
+another one.
+
+[[maxclockerror]]*maxclockerror* _error-in-ppm_::
+The *maxclockerror* directive sets the maximum assumed frequency error that the
+system clock can gain on its own between clock updates. It describes the
+stability of the clock.
++
+By default, the maximum error is 1 ppm.
++
+Typical values for _error-in-ppm_ might be 10 for a low quality clock and 0.1
+for a high quality clock using a temperature compensated crystal oscillator.
+
+[[maxdrift]]*maxdrift* _drift-in-ppm_::
+This directive specifies the maximum assumed drift (frequency error) of the
+system clock. It limits the frequency adjustment that *chronyd* is allowed to
+use to correct the measured drift. It is an additional limit to the maximum
+adjustment that can be set by the system driver (100000 ppm on Linux, 500 ppm
+on FreeBSD, NetBSD, and macOS 10.13+, 32500 ppm on illumos).
++
+By default, the maximum assumed drift is 500000 ppm, i.e. the adjustment is
+limited by the system driver rather than this directive.
+
+[[maxupdateskew]]*maxupdateskew* _skew-in-ppm_::
+One of *chronyd*'s tasks is to work out how fast or slow the computer's clock
+runs relative to its reference sources. In addition, it computes an estimate of
+the error bounds around the estimated value.
++
+If the range of error is too large, it probably indicates that the measurements
+have not settled down yet, and that the estimated gain or loss rate is not very
+reliable.
++
+The *maxupdateskew* directive sets the threshold for determining whether an
+estimate might be so unreliable that it should not be used. By default, the
+threshold is 1000 ppm.
++
+Typical values for _skew-in-ppm_ might be 100 for NTP sources polled over a
+wireless network, and 10 or smaller for sources on a local wired network.
++
+It should be noted that this is not the only means of protection against using
+unreliable estimates. At all times, *chronyd* keeps track of both the estimated
+gain or loss rate, and the error bound on the estimate. When a new estimate is
+generated following another measurement from one of the sources, a weighted
+combination algorithm is used to update the master estimate. So if *chronyd*
+has an existing highly-reliable master estimate and a new estimate is generated
+which has large error bounds, the existing master estimate will dominate in the
+new master estimate.
+
+[[maxslewrate]]*maxslewrate* _rate-in-ppm_::
+The *maxslewrate* directive sets the maximum rate at which *chronyd* is allowed
+to slew the time. It limits the slew rate controlled by the correction time
+ratio (which can be set by the <<corrtimeratio,*corrtimeratio*>> directive) and
+is effective only on systems where *chronyd* is able to control the rate (i.e.
+all supported systems with the exception of macOS 12 or earlier).
++
+For each system there is a maximum frequency offset of the clock that can be set
+by the driver. On Linux it is 100000 ppm, on FreeBSD, NetBSD and macOS 10.13+ it
+is 5000 ppm, and on illumos it is 32500 ppm. Also, due to a kernel limitation,
+setting *maxslewrate* on FreeBSD, NetBSD, macOS 10.13+ to a value between 500
+ppm and 5000 ppm will effectively set it to 500 ppm.
++
+By default, the maximum slew rate is set to 83333.333 ppm (one twelfth).
+
+[[tempcomp]]
+*tempcomp* _file_ _interval_ _T0_ _k0_ _k1_ _k2_::
+*tempcomp* _file_ _interval_ _points-file_::
+Normally, changes in the rate of drift of the system clock are caused mainly by
+changes in the temperature of the crystal oscillator on the motherboard.
++
+If there are temperature measurements available from a sensor close to the
+oscillator, the *tempcomp* directive can be used to compensate for the changes
+in the temperature and improve the stability and accuracy of the clock.
++
+The result depends on many factors, including the resolution of the sensor, the
+amount of noise in the measurements, the polling interval of the time source,
+the compensation update interval, how well the compensation is specified, and
+how close the sensor is to the oscillator. When it is working well, the
+frequency reported in the _tracking.log_ file is more stable and the maximum
+reached offset is smaller.
++
+There are two forms of the directive. The first one has six parameters: a path
+to the file containing the current temperature from the sensor (in text
+format), the compensation update interval (in seconds), and temperature
+coefficients _T0_, _k0_, _k1_, _k2_.
++
+The frequency compensation is calculated (in ppm) as
++
+----
+comp = k0 + (T - T0) * k1 + (T - T0)^2 * k2
+----
++
+The result has to be between -10 ppm and 10 ppm, otherwise the measurement is
+considered invalid and will be ignored. The _k0_ coefficient can be adjusted to
+keep the compensation in that range.
++
+An example of the use is:
++
+----
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 26000 0.0 0.000183 0.0
+----
++
+The measured temperature will be read from the file in the Linux sysfs
+filesystem every 30 seconds. When the temperature is 26000 (26 degrees
+Celsius), the frequency correction will be zero. When it is 27000 (27 degrees
+Celsius), the clock will be set to run faster by 0.183 ppm, etc.
++
+The second form has three parameters: the path to the sensor file, the update
+interval, and a path to a file containing a list of (temperature, compensation)
+points, from which the compensation is linearly interpolated or extrapolated.
++
+An example is:
++
+----
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 /etc/chrony.tempcomp
+----
++
+where the _/etc/chrony.tempcomp_ file could have
++
+----
+20000 1.0
+21000 0.64
+22000 0.36
+23000 0.16
+24000 0.04
+25000 0.0
+26000 0.04
+27000 0.16
+28000 0.36
+29000 0.64
+30000 1.0
+----
++
+Valid measurements with corresponding compensations are logged to the
+_tempcomp.log_ file if enabled by the <<log,*log tempcomp*>> directive.
+
+=== NTP server
+
+[[allow]]*allow* [*all*] [_subnet_]::
+The *allow* directive is used to designate a particular subnet from which NTP
+clients are allowed to access the computer as an NTP server. It also controls
+access of NTS-KE clients when NTS is enabled on the server.
++
+The default is that no clients are allowed access, i.e. *chronyd* operates
+purely as an NTP client. If the *allow* directive is used, *chronyd* will be
+both a client of its servers, and a server to other clients.
++
+This directive can be used multiple times.
++
+Examples of the use of the directive are as follows:
++
+----
+allow 1.2.3.4
+allow 3.4.5.0/24
+allow 3.4.5
+allow 2001:db8::/32
+allow 0/0
+allow ::/0
+allow
+----
++
+The first directive allows access from an IPv4 address. The second directive
+allows access from all computers in an IPv4 subnet specified in the CIDR
+notation. The third directive specifies the same subnet using a simpler
+notation where the prefix length is determined by the number of dots. The
+fourth directive specifies an IPv6 subnet. The fifth and sixth directives allow
+access from all IPv4 and IPv6 addresses respectively. The seventh directive
+allows access from all addresses (both IPv4 or IPv6).
++
+A second form of the directive, *allow all*, has a greater effect, depending on
+the ordering of directives in the configuration file. To illustrate the effect,
+consider the two examples:
++
+----
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow 1.2.0.0/16
+----
++
+and
++
+----
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow all 1.2.0.0/16
+----
++
+In the first example, the effect is the same regardless of what order the three
+directives are given in. So the _1.2.0.0/16_ subnet is allowed access, except
+for the _1.2.3.0/24_ subnet, which is denied access, however the host _1.2.3.4_
+is allowed access.
++
+In the second example, the *allow all 1.2.0.0/16* directive overrides the
+effect of _any_ previous directive relating to a subnet within the specified
+subnet. Within a configuration file this capability is probably rather moot;
+however, it is of greater use for reconfiguration at run-time via *chronyc*
+with the <<chronyc.adoc#allow,*allow all*>> command.
++
+The rules are internally represented as a tree of tables with one level per
+four bits of the IPv4 or IPv6 address. The order of the *allow* and *deny*
+directives matters if they modify the same records of one table, i.e. if one
+subnet is included in the other subnet and their prefix lengths are at the same
+level. For example, _1.2.3.0/28_ and _1.2.3.0/29_ are in different tables, but
+_1.2.3.0/25_ and _1.2.3.0/28_ are in the same table. The configuration can be
+verified for individual addresses with the <<chronyc.adoc#accheck,*accheck*>>
+command in *chronyc*.
++
+A hostname can be specified in the directives instead of the IP address, but
+the name must be resolvable when *chronyd* is started, i.e. the network is
+already up and DNS is working. If the hostname resolves to multiple addresses,
+only the first address (in the order returned by the system resolver) will be
+allowed or denied.
++
+Note, if the <<initstepslew,*initstepslew*>> directive is used in the
+configuration file, each of the computers listed in that directive must allow
+client access by this computer for it to work.
+
+[[deny]]*deny* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> directive, except that it denies NTP
+and NTS-KE client access to a particular subnet or host, rather than allowing
+it.
++
+The syntax is identical and the directive can be used multiple times too.
++
+There is also a *deny all* directive with similar behaviour to the *allow all*
+directive.
+
+[[bindaddress]]*bindaddress* _address_::
+The *bindaddress* directive binds the sockets on which *chronyd* listens for
+NTP and NTS-KE requests to a local address of the computer. On systems other
+than Linux, the address of the computer needs to be already configured when
+*chronyd* is started.
++
+An example of the use of the directive is:
++
+----
+bindaddress 192.168.1.1
+----
++
+Currently, for each of the IPv4 and IPv6 protocols, only one *bindaddress*
+directive can be specified. Therefore, it is not useful on computers which
+should serve NTP on multiple network interfaces.
+
+[[binddevice]]*binddevice* _interface_::
+The *binddevice* directive binds the NTP and NTS-KE server sockets to a network
+device specified by the interface name. This directive can specify only one
+interface and it is supported on Linux only.
++
+An example of the directive is:
++
+----
+binddevice eth0
+----
+
+[[broadcast]]*broadcast* _interval_ _address_ [_port_]::
+The *broadcast* directive is used to declare a broadcast address to which
+chronyd should send packets in the NTP broadcast mode (i.e. make *chronyd* act
+as a broadcast server). Broadcast clients on that subnet will be able to
+synchronise.
++
+This directive can be used multiple times to specify multiple addresses.
++
+The syntax is as follows:
++
+----
+broadcast 32 192.168.1.255
+broadcast 64 192.168.2.255 12123
+broadcast 64 ff02::101
+----
++
+In the first example, the destination port defaults to UDP port 123 (the normal NTP
+port). In the second example, the destination port is specified as 12123. The
+first parameter in each case (32 or 64 respectively) is the interval in seconds
+between broadcast packets being sent. The second parameter in each case is the
+broadcast address to send the packet to. This should correspond to the
+broadcast address of one of the network interfaces on the computer where
+*chronyd* is running.
++
+You can have more than 1 *broadcast* directive if you have more than 1 network
+interface onto which you want to send NTP broadcast packets.
++
+*chronyd* itself cannot act as a broadcast client; it must always be configured
+as a point-to-point client by defining specific NTP servers and peers. This
+broadcast server feature is intended for providing a time source to other NTP
+implementations.
++
+If *ntpd* is used as the broadcast client, it will try to measure the
+round-trip delay between the server and client with normal client mode packets.
+Thus, the broadcast subnet should also be the subject of an <<allow,*allow*>>
+directive.
+
+[[clientloglimit]]*clientloglimit* _limit_::
+This directive specifies the maximum amount of memory that *chronyd* is allowed
+to allocate for logging of client accesses and the state that *chronyd* as an
+NTP server needs to support the interleaved mode for its clients. The default
+limit is 524288 bytes, which enables monitoring of up to 4096 IP addresses at
+the same time and holding NTP timestamps for up to 4096 clients using the
+interleaved mode (depending on uniformity of their polling interval). The
+number of addresses and timestamps is always a power of 2. The maximum
+effective value is 2147483648 (2 GB), which corresponds to 16777216 addresses
+and timestamps.
++
+An example of the use of this directive is:
++
+----
+clientloglimit 1048576
+----
+
+[[noclientlog]]*noclientlog*::
+This directive, which takes no arguments, specifies that client accesses are
+not to be logged. Normally they are logged, allowing statistics to be reported
+using the <<chronyc.adoc#clients,*clients*>> command in *chronyc*. This option
+also effectively disables server support for the NTP interleaved mode.
+
+[[local]]*local* [_option_]...::
+The *local* directive enables a local reference mode, which allows *chronyd*
+operating as an NTP server to appear synchronised to real time (from the
+viewpoint of clients polling it), even when it was never synchronised or
+the last update of the clock happened a long time ago.
++
+This directive is normally used in an isolated network, where computers are
+required to be synchronised to one another, but not necessarily to real time.
+The server can be kept vaguely in line with real time by manual input.
++
+The *local* directive has the following options:
++
+*stratum* _stratum_:::
+This option sets the stratum of the server which will be reported to clients
+when the local reference is active. The specified value is in the range 1
+through 15, and the default value is 10. It should be larger than the maximum
+expected stratum in the network when external NTP servers are accessible.
++
+Stratum 1 indicates a computer that has a true real-time reference directly
+connected to it (e.g. GPS, atomic clock, etc.), such computers are expected to
+be very close to real time. Stratum 2 computers are those which have a stratum
+1 server; stratum 3 computers have a stratum 2 server and so on. A value
+of 10 indicates that the clock is so many hops away from a reference clock that
+its time is fairly unreliable.
+*distance* _distance_:::
+This option sets the threshold for the root distance which will activate the local
+reference. If *chronyd* was synchronised to some source, the local reference
+will not be activated until its root distance reaches the specified value (the
+rate at which the distance is increasing depends on how well the clock was
+tracking the source). The default value is 1 second.
++
+The current root distance can be calculated from root delay and root dispersion
+(reported by the <<chronyc.adoc#tracking,*tracking*>> command in *chronyc*) as:
++
+----
+distance = delay / 2 + dispersion
+----
+*orphan*:::
+This option enables a special '`orphan`' mode, where sources with stratum equal
+to the local _stratum_ are assumed to not serve real time. They are ignored
+unless no other source is selectable and their reference IDs are smaller than
+the local reference ID.
++
+This allows multiple servers in the network to use the same *local*
+configuration and to be synchronised to one another, without confusing clients
+that poll more than one server. Each server needs to be configured to poll all
+other servers with the *local* directive. This ensures only the server with the
+smallest reference ID has the local reference active and others are
+synchronised to it. If that server stops responding, the server with the second
+smallest reference ID will take over when its local reference mode activates
+(root distance reaches the threshold configured by the *distance* option).
++
+The *orphan* mode is compatible with the *ntpd*'s orphan mode (enabled by the
+*tos orphan* command).
+{blank}::
++
+An example of the directive is:
++
+----
+local stratum 10 orphan distance 0.1
+----
+
+[[ntpsigndsocket]]*ntpsigndsocket* _directory_::
+This directive specifies the location of the Samba *ntp_signd* socket when it
+is running as a Domain Controller (DC). If *chronyd* is compiled with this
+feature, responses to MS-SNTP clients will be signed by the *smbd* daemon.
++
+Note that MS-SNTP requests are not authenticated and any client that is allowed
+to access the server by the <<allow,*allow*>> directive, or the
+<<chronyc.adoc#allow,*allow*>> command in *chronyc*, can get an MS-SNTP
+response signed with a trust account's password and try to crack the password
+in a brute-force attack. Access to the server should be carefully controlled.
++
+An example of the directive is:
++
+----
+ntpsigndsocket /var/lib/samba/ntp_signd
+----
+
+[[ntsport]]*ntsport* _port_::
+This directive specifies the TCP port on which *chronyd* will provide the NTS
+Key Establishment (NTS-KE) service. The default port is 4460.
++
+The port will be open only when a certificate and key is specified by the
+*ntsservercert* and *ntsserverkey* directives.
+
+[[ntsservercert]]*ntsservercert* _file_::
+This directive specifies a file containing a certificate in the PEM format
+for *chronyd* to operate as an NTS server. The file should also include
+any intermediate certificates that the clients will need to validate the
+server's certificate. The file needs to be readable by the user under which
+*chronyd* is running after dropping root privileges.
++
+This directive can be used multiple times to specify multiple certificates for
+different names of the server.
++
+The files are loaded only once. *chronyd* needs to be restarted in order to
+load a renewed certificate. The <<ntsdumpdir,*ntsdumpdir*>> and
+<<dumpdir,*dumpdir*>> directives with the *-r* option of *chronyd* are
+recommended for a near-seamless server operation.
+
+[[ntsserverkey]]*ntsserverkey* _file_::
+This directive specifies a file containing a private key in the PEM format
+for *chronyd* to operate as an NTS server. The file needs to be readable by
+the user under which *chronyd* is running after dropping root privileges. For
+security reasons, it should not be readable by other users.
++
+This directive can be used multiple times to specify multiple keys. The number
+of keys must be the same as the number of certificates and the corresponding
+files must be specified in the same order.
+
+[[ntsprocesses]]*ntsprocesses* _processes_::
+This directive specifies how many helper processes will *chronyd* operating
+as an NTS server start for handling client NTS-KE requests in order to improve
+performance with multi-core CPUs and multithreading. If set to 0, no helper
+process will be started and all NTS-KE requests will be handled by the main
+*chronyd* process. The default value is 1.
+
+[[maxntsconnections]]*maxntsconnections* _connections_::
+This directive specifies the maximum number of concurrent NTS-KE connections
+per process that the NTS server will accept. The default value is 100. The
+maximum practical value is half of the system *FD_SETSIZE* constant (usually
+1024).
+
+[[ntsdumpdir2]]*ntsdumpdir* _directory_::
+This directive specifies a directory where *chronyd* operating as an NTS server
+can save the keys which encrypt NTS cookies provided to clients. The keys are
+saved to a single file named _ntskeys_. When *chronyd* is restarted, reloading
+the keys allows the clients to continue using old cookies and avoids a storm of
+NTS-KE requests. By default, the server does not save the keys.
++
+An example of the directive is:
++
+----
+ntsdumpdir @CHRONYVARDIR@
+----
++
+This directory is used also by the <<ntsdumpdir1,NTS client>> to save NTS cookies.
+
+[[ntsntpserver]]*ntsntpserver* _hostname_::
+This directive specifies the hostname (as a fully qualified domain name) or
+address of the NTP server(s) which is
+provided in the NTS-KE response to the clients. It allows the NTS-KE server to
+be separated from the NTP server. However, the servers need to share the keys,
+i.e. external key management needs to be enabled by setting
+<<ntsrotate,*ntsrotate*>> to 0. By default, no hostname or address is provided
+to the clients, which means they should use the same server for NTS-KE and NTP.
+
+[[ntsrotate]]*ntsrotate* _interval_::
+This directive specifies the rotation interval (in seconds) of the server key
+which encrypts the NTS cookies. New keys are generated automatically from the
+_/dev/urandom_ device. The server keeps two previous keys to give the clients
+time to get new cookies encrypted by the latest key. The interval is measured
+as the server's operating time, i.e. the actual interval can be longer if
+*chronyd* is not running continuously. The default interval is 604800 seconds
+(1 week). The maximum value is 2^31-1 (68 years).
++
+The automatic rotation of the keys can be disabled by setting *ntsrotate* to 0.
+In this case the keys are assumed to be managed externally. *chronyd* will not
+save the keys to the _ntskeys_ file and will reload the keys from the file when
+the <<chronyc.adoc#rekey,*rekey*>> command is issued in *chronyc*. The file can
+be periodically copied from another server running *chronyd* (which does
+not have *ntsrotate* set to 0) in order to have one or more servers dedicated
+to NTS-KE. The NTS-KE servers need to be configured with the
+<<ntsntpserver,*ntsntpserver*>> directive to point the clients to the right NTP
+server.
++
+An example of the directive is:
++
+----
+ntsrotate 2592000
+----
+
+[[port]]*port* _port_::
+This option allows you to configure the port on which *chronyd* will listen for
+NTP requests. The port will be open only when an address is allowed by the
+<<allow,*allow*>> directive or the <<chronyc.adoc#allow,*allow*>> command in
+*chronyc*, an NTP peer is configured, or the broadcast server mode is enabled.
++
+The default value is 123, the standard NTP port. If set to 0, *chronyd* will
+never open the server port and will operate strictly in a client-only mode. The
+source port used in NTP client requests can be set by the
+<<acquisitionport,*acquisitionport*>> directive.
+
+[[ratelimit]]*ratelimit* [_option_]...::
+This directive enables response rate limiting for NTP packets. Its purpose is
+to reduce network traffic with misconfigured or broken NTP clients that are
+polling the server too frequently. The limits are applied to individual IP
+addresses. If multiple clients share one IP address (e.g. multiple hosts behind
+NAT), the sum of their traffic will be limited. If a client that increases its
+polling rate when it does not receive a reply is detected, its rate limiting
+will be temporarily suspended to avoid increasing the overall amount of
+traffic. The maximum number of IP addresses which can be monitored at the same
+time depends on the memory limit set by the <<clientloglimit,*clientloglimit*>>
+directive.
++
+The *ratelimit* directive supports a number of options (which can be defined
+in any order):
++
+*interval* _interval_:::
+This option sets the minimum interval between responses. It is defined as a
+power of 2 in seconds. The default value is 3 (8 seconds). The minimum value
+is -19 (524288 packets per second) and the maximum value is 12 (one packet per
+4096 seconds). Note that with values below -4 the rate limiting is coarse
+(responses are allowed in bursts, even if the interval between them is shorter
+than the specified interval).
+*burst* _responses_:::
+This option sets the maximum number of responses that can be sent in a burst,
+temporarily exceeding the limit specified by the *interval* option. This is
+useful for clients that make rapid measurements on start (e.g. *chronyd* with
+the *iburst* option). The default value is 8. The minimum value is 1 and the
+maximum value is 255.
+*leak* _rate_:::
+This option sets the rate at which responses are randomly allowed even if the
+limits specified by the *interval* and *burst* options are exceeded. This is
+necessary to prevent an attacker who is sending requests with a spoofed
+source address from completely blocking responses to that address. The leak
+rate is defined as a power of 1/2 and it is 2 by default, i.e. on average at
+least every fourth request has a response. The minimum value is 1 and the
+maximum value is 4.
+{blank}::
++
+An example use of the directive is:
++
+----
+ratelimit interval 1 burst 16
+----
++
+This would reduce the response rate for IP addresses sending packets on average
+more than once per 2 seconds, or sending packets in bursts of more than 16
+packets, by up to 75% (with default *leak* of 2).
+
+[[ntsratelimit]]*ntsratelimit* [_option_]...::
+This directive enables rate limiting of NTS-KE requests. It is similar to the
+<<ratelimit,*ratelimit*>> directive, except the default interval is 6
+(1 connection per 64 seconds).
++
+An example of the use of the directive is:
++
+----
+ntsratelimit interval 3 burst 1
+----
+
+[[smoothtime]]*smoothtime* _max-freq_ _max-wander_ [*leaponly*]::
+The *smoothtime* directive can be used to enable smoothing of the time that
+*chronyd* serves to its clients to make it easier for them to track it and keep
+their clocks close together even when large offset or frequency corrections are
+applied to the server's clock, for example after being offline for a longer
+time.
++
+BE WARNED: The server is intentionally not serving its best estimate of the
+true time. If a large offset has been accumulated, it can take a very long time
+to smooth it out. This directive should be used only when the clients are not
+configured to also poll another NTP server, because they could reject this
+server as a falseticker or fail to select a source completely.
++
+The smoothing process is implemented with a quadratic spline function with two
+or three pieces. It is independent from any slewing applied to the local system
+clock, but the accumulated offset and frequency will be reset when the clock is
+corrected by stepping, e.g. by the <<makestep,*makestep*>> directive or the
+<<chronyc.adoc#makestep,*makestep*>> command in *chronyc*. The process can be
+reset without stepping the clock by the <<chronyc.adoc#smoothtime,*smoothtime
+reset*>> command.
++
+The first two arguments of the directive are the maximum frequency offset of
+the smoothed time to the tracked NTP time (in ppm) and the maximum rate at
+which the frequency offset is allowed to change (in ppm per second). *leaponly*
+is an optional third argument which enables a mode where only leap seconds are
+smoothed out and normal offset and frequency changes are ignored. The *leaponly*
+option is useful in a combination with the <<leapsecmode,*leapsecmode slew*>>
+directive to allow the clients to use multiple time smoothing servers safely.
++
+The smoothing process is activated automatically when 1/10000 of the estimated
+skew of the local clock falls below the maximum rate of frequency change. It
+can be also activated manually by the <<chronyc.adoc#smoothtime,*smoothtime
+activate*>> command, which is particularly useful when the clock is
+synchronised only with manual input and the skew is always larger than the
+threshold. The <<chronyc.adoc#smoothing,*smoothing*>> command can be used to
+monitor the process.
++
+An example suitable for clients using *ntpd* and 1024 second polling interval
+could be:
++
+----
+smoothtime 400 0.001
+----
++
+An example suitable for clients using *chronyd* on Linux could be:
++
+----
+smoothtime 50000 0.01
+----
+
+=== Command and monitoring access
+
+[[bindcmdaddress]]*bindcmdaddress* _address_::
+The *bindcmdaddress* directive specifies a local IP address to which *chronyd*
+will bind the UDP socket listening for monitoring command packets (issued
+by *chronyc*). On systems other than Linux, the address of the interface needs
+to be already configured when *chronyd* is started.
++
+This directive can also change the path of the Unix domain command socket,
+which is used by *chronyc* to send configuration commands. The socket must be
+in a directory that is accessible only by the root or _chrony_ user. The
+directory will be created on start if it does not exist. The compiled-in default
+path of the socket is _@CHRONYRUNDIR@/chronyd.sock_. The socket can be
+disabled by setting the path to _/_.
++
+By default, *chronyd* binds the UDP sockets to the addresses _127.0.0.1_ and
+_::1_ (i.e. the loopback interface). This blocks all access except from
+localhost. To listen for command packets on all interfaces, you can add the
+lines:
++
+----
+bindcmdaddress 0.0.0.0
+bindcmdaddress ::
+----
++
+to the configuration file.
++
+For each of the IPv4, IPv6, and Unix domain protocols, only one
+*bindcmdaddress* directive can be specified.
++
+An example that sets the path of the Unix domain command socket is:
++
+----
+bindcmdaddress /var/run/chrony/chronyd.sock
+----
+
+[[bindcmddevice]]*bindcmddevice* _interface_::
+The *bindcmddevice* directive binds the UDP command sockets to a network device
+specified by the interface name. This directive can specify only one interface
+and it is supported on Linux only.
++
+An example of the directive is:
++
+----
+bindcmddevice eth0
+----
+
+[[cmdallow]]*cmdallow* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> directive, except that it allows
+monitoring access (rather than NTP client access) to a particular subnet or
+host. (By '`monitoring access`' is meant that *chronyc* can be run on those
+hosts and retrieve monitoring data from *chronyd* on this computer.)
++
+The syntax is identical to the *allow* directive.
++
+There is also a *cmdallow all* directive with similar behaviour to the *allow
+all* directive (but applying to monitoring access in this case, of course).
++
+Note that *chronyd* has to be configured with the
+<<bindcmdaddress,*bindcmdaddress*>> directive to not listen only on the
+loopback interface to actually allow remote access.
+
+[[cmddeny]]*cmddeny* [*all*] [_subnet_]::
+This is similar to the <<cmdallow,*cmdallow*>> directive, except that it denies
+monitoring access to a particular subnet or host, rather than allowing it.
++
+The syntax is identical.
++
+There is also a *cmddeny all* directive with similar behaviour to the *cmdallow
+all* directive.
+
+[[cmdport]]*cmdport* _port_::
+The *cmdport* directive allows the port that is used for run-time monitoring
+(via the *chronyc* program) to be altered from its default (323). If set to 0,
+*chronyd* will not open the port, this is useful to disable *chronyc*
+access from the Internet. (It does not disable the Unix domain command socket.)
++
+An example shows the syntax:
++
+----
+cmdport 257
+----
++
+This would make *chronyd* use UDP 257 as its command port. (*chronyc* would
+need to be run with the *-p 257* switch to inter-operate correctly.)
+
+[[cmdratelimit]]*cmdratelimit* [_option_]...::
+This directive enables response rate limiting for command packets. It is
+similar to the <<ratelimit,*ratelimit*>> directive, except responses to
+localhost are never limited and the default interval is -4 (16 packets per
+second).
++
+An example of the use of the directive is:
++
+----
+cmdratelimit interval 2
+----
+
+=== Real-time clock (RTC)
+
+[[hwclockfile]]*hwclockfile* _file_::
+The *hwclockfile* directive sets the location of the adjtime file which is
+used by the *hwclock* program on Linux. *chronyd* parses the file to find out
+if the RTC keeps local time or UTC. It overrides the <<rtconutc,*rtconutc*>>
+directive.
++
+The compiled-in default value is '_@DEFAULT_HWCLOCK_FILE@_'.
++
+An example of the directive is:
++
+----
+hwclockfile /etc/adjtime
+----
+
+[[rtcautotrim]]*rtcautotrim* _threshold_::
+The *rtcautotrim* directive is used to keep the RTC close to the system clock
+automatically. When the system clock is synchronised and the estimated error
+between the two clocks is larger than the specified threshold, *chronyd* will
+trim the RTC as if the <<chronyc.adoc#trimrtc,*trimrtc*>> command in *chronyc*
+was issued. The trimming operation is accurate to only about 1 second, which is
+the minimum effective threshold.
++
+This directive is effective only with the <<rtcfile,*rtcfile*>> directive.
++
+An example of the use of this directive is:
++
+----
+rtcautotrim 30
+----
++
+This would set the threshold error to 30 seconds.
+
+[[rtcdevice]]*rtcdevice* _device_::
+The *rtcdevice* directive sets the path to the device file for accessing the
+RTC. The default path is _@DEFAULT_RTC_DEVICE@_.
+
+[[rtcfile]]*rtcfile* _file_::
+The *rtcfile* directive defines the name of the file in which *chronyd* can
+save parameters associated with tracking the accuracy of the RTC.
++
+An example of the directive is:
++
+----
+rtcfile @CHRONYVARDIR@/rtc
+----
++
+*chronyd* saves information in this file when it exits and when the *writertc*
+command is issued in *chronyc*. The information saved is the RTC's error at
+some epoch, that epoch (in seconds since January 1 1970), and the rate at which
+the RTC gains or loses time.
++
+So far, the support for real-time clocks is limited; their code is even more
+system-specific than the rest of the software. You can only use the RTC
+facilities (the <<rtcfile,*rtcfile*>> directive and the *-s* command-line
+option to *chronyd*) if the following three conditions apply:
++
+. You are running Linux.
+. The kernel is compiled with extended real-time clock support (i.e. the
+  _/dev/rtc_ device is capable of doing useful things).
+. You do not have other applications that need to make use of _/dev/rtc_ at all.
+
+[[rtconutc]]*rtconutc*::
+*chronyd* assumes by default that the RTC keeps local time (including any
+daylight saving changes). This is convenient on PCs running Linux which are
+dual-booted with Windows.
++
+If you keep the RTC on local time and your computer is off when daylight saving
+(summer time) starts or ends, the computer's system time will be one hour in
+error when you next boot and start chronyd.
++
+An alternative is for the RTC to keep Universal Coordinated Time (UTC). This
+does not suffer from the 1 hour problem when daylight saving starts or ends.
++
+If the *rtconutc* directive appears, it means the RTC is required to keep UTC.
+The directive takes no arguments. It is equivalent to specifying the *-u*
+switch to the Linux *hwclock* program.
++
+Note that this setting is overridden by the <<hwclockfile,*hwclockfile*>> file
+and is not relevant for the <<rtcsync,*rtcsync*>> directive.
+
+[[rtcsync]]*rtcsync*::
+The *rtcsync* directive enables a mode where the system time is periodically
+copied to the RTC and *chronyd* does not try to track its drift. This directive
+cannot be used with the <<rtcfile,*rtcfile*>> directive.
++
+On Linux, the RTC copy is performed by the kernel every 11 minutes.
++
+On macOS, <<chronyd,*chronyd*>> will perform the RTC copy every 60 minutes
+when the system clock is in a synchronised state.
++
+On other systems this directive does nothing.
+
+=== Logging
+
+[[log]]*log* [_option_]...::
+The *log* directive indicates that certain information is to be logged.
+The log files are written to the directory specified by the <<logdir,*logdir*>>
+directive. A banner is periodically written to the files to indicate the
+meanings of the columns.
++
+*rawmeasurements*:::
+This option logs the raw NTP measurements and related information to a file
+called _measurements.log_. An entry is made for each packet received from the
+source. This can be useful when debugging a problem. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
++
+----
+2016-11-09 05:40:50 203.0.113.15    N  2 111 111 1111  10 10 1.0 \
+   -4.966e-03  2.296e-01  1.577e-05  1.615e-01  7.446e-03 CB00717B 4B D K
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-10-13]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [05:40:50]
+. IP address of server or peer from which measurement came [203.0.113.15]
+. Leap status (_N_ means normal, _+_ means that the last minute of the current
+  month has 61 seconds, _-_ means that the last minute of the month has 59
+  seconds, _?_ means the remote computer is not currently synchronised.) [N]
+. Stratum of remote computer. [2]
+. RFC 5905 tests 1 through 3 (1=pass, 0=fail) [111]
+. RFC 5905 tests 5 through 7 (1=pass, 0=fail) [111]
+. Results of the *maxdelay*, *maxdelayratio*, and *maxdelaydevratio* (or
+  *maxdelayquant*) tests, and a test for synchronisation loop (1=pass,
+  0=fail). The first test from these four also checks the server precision,
+  response time, and whether an interleaved response is acceptable for
+  synchronisation. [1111]
+. Local poll [10]
+. Remote poll [10]
+. '`Score`' (an internal score within each polling level used to decide when to
+  increase or decrease the polling level. This is adjusted based on number of
+  measurements currently being used for the regression algorithm). [1.0]
+. The estimated local clock error (_theta_ in RFC 5905). Positive indicates
+  that the local clock is slow of the remote source. [-4.966e-03]
+. The peer delay (_delta_ in RFC 5905). [2.296e-01]
+. The peer dispersion (_epsilon_ in RFC 5905). [1.577e-05]
+. The root delay (_DELTA_ in RFC 5905). [1.615e-01]
+. The root dispersion (_EPSILON_ in RFC 5905). [7.446e-03]
+. Reference ID of the server's source as a hexadecimal number. [CB00717B]
+. NTP mode of the received packet (_1_=active peer, _2_=passive peer,
+  _4_=server, _B_=basic, _I_=interleaved). [4B]
+. Source of the local transmit timestamp
+  (_D_=daemon, _K_=kernel, _H_=hardware). [D]
+. Source of the local receive timestamp
+  (_D_=daemon, _K_=kernel, _H_=hardware). [K]
++
+*measurements*:::
+This option is identical to the *rawmeasurements* option, except it logs only
+valid measurements from synchronised sources, i.e. measurements which passed
+the RFC 5905 tests 1 through 7. This can be useful for producing graphs of the
+source's performance.
++
+*statistics*:::
+This option logs information about the regression processing to a file called
+_statistics.log_. An example line (which actually appears as a single line in
+the file) from the log file is shown below.
++
+----
+2016-08-10 05:40:50 203.0.113.15     6.261e-03 -3.247e-03 \
+     2.220e-03  1.874e-06  1.080e-06 7.8e-02  16   0   8  0.00
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-07-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [05:40:50]
+. IP address of server or peer from which measurement comes [203.0.113.15]
+. The estimated standard deviation of the measurements from the source (in
+  seconds). [6.261e-03]
+. The estimated offset of the source (in seconds, positive means the local
+  clock is estimated to be fast, in this case). [-3.247e-03]
+. The estimated standard deviation of the offset estimate (in seconds).
+  [2.220e-03]
+. The estimated rate at which the local clock is gaining or losing time
+  relative to the source (in seconds per second, positive means the local clock
+  is gaining). This is relative to the compensation currently being applied to
+  the local clock, _not_ to the local clock without any compensation.
+  [1.874e-06]
+. The estimated error in the rate value (in seconds per second). [1.080e-06].
+. The ratio of |old_rate - new_rate| / old_rate_error. Large values
+  indicate the statistics are not modelling the source very well. [7.8e-02]
+. The number of measurements currently being used for the regression
+  algorithm. [16]
+. The new starting index (the oldest sample has index 0; this is the method
+  used to prune old samples when it no longer looks like the measurements fit a
+  linear model). [0, i.e. no samples discarded this time]
+. The number of runs. The number of runs of regression residuals with the same
+  sign is computed. If this is too small it indicates that the measurements are
+  no longer represented well by a linear model and that some older samples need
+  to be discarded. The number of runs for the data that is being retained is
+  tabulated. Values of approximately half the number of samples are expected.
+  [8]
+. The estimated or configured asymmetry of network jitter on the path to the
+  source which was used to correct the measured offsets. The asymmetry can be
+  between -0.5 and +0.5. A negative value means the delay of packets sent to
+  the source is more variable than the delay of packets sent from the source
+  back. [0.00, i.e. no correction for asymmetry]
++
+*selection*:::
+This option logs information about selection of sources for synchronisation to
+a file called _selection.log_. Note that the rate of entries written to this
+file grows quadratically with the number of specified sources (each measurement
+triggers the selection for all sources). An example line (which actually
+appears as a single line in the file) from the log file is shown below.
++
+----
+2022-05-01 02:01:20 203.0.113.15    * -----  377  1.00  \
+     4.228e+01 -1.575e-04  1.239e-04
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2022-05-01]
+. Hour:Minute:Second. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [02:01:20]
+. IP address or reference ID of the source. [203.0.113.15]
+. State of the source indicated with one of the following symbols. [*]
+{blank}::::
+Not considered selectable for synchronisation:
+* _N_ - has the *noselect* option.
+* _s_ - is not synchronised.
+* _M_ - does not have enough measurements.
+* _d_ - has a root distance larger than the maximum distance (configured by the
+        <<maxdistance,*maxdistance*>> directive).
+* _~_ - has a jitter larger than the maximum jitter (configured by the
+        <<maxjitter,*maxjitter*>> directive).
+* _w_ - waits for other sources to get out of the _M_ state.
+* _S_ - has older measurements than other sources.
+* _O_ - has a stratum equal or larger than the orphan stratum (configured by
+        the <<local,*local*>> directive).
+* _T_ - does not fully agree with sources that have the *trust* option.
+* _x_ - does not agree with other sources (falseticker).
+{blank}::::
+Considered selectable for synchronisation, but not currently used:
+* _W_ - waits for other sources to be selectable (required by the
+        <<minsources,*minsources*>> directive, or the *require* option of
+        another source).
+* _P_ - another selectable source is preferred due to the *prefer* option.
+* _U_ - waits for a new measurement (after selecting a different best source).
+* _D_ - has, or recently had, a root distance which is too large to be combined
+        with other sources (configured by the <<combinelimit,*combinelimit*>>
+        directive).
+{blank}::::
+Used for synchronisation of the local clock:
+* _+_ - combined with the best source.
+* _*_ - selected as the best source to update the reference data (e.g. root
+        delay, root dispersion).
+. Reachability register printed as an octal number. The register has 8 bits and
+  is updated on every received or missed packet from the source. A value of 377
+  indicates that a valid reply was received for all from the last eight
+  transmissions. [377]
+. Current score against the source in the _*_ state. The scoring system avoids
+  frequent reselection when multiple sources have a similar root distance. A
+  value larger than 1 indicates this source was better than the _*_ source in
+  recent selections. If the score reaches 10, the best source will be reselected
+  and the scores will be reset to 1. [1.00]
+. Interval since the last measurement of the source in seconds. [4.228e+01]
+. Lower endpoint of the interval which was expected to contain the true offset
+  of the local clock determined by the root distance of the source. [-1.575e-04]
+. Upper endpoint of the interval which was expected to contain the true offset
+  of the local clock determined by the root distance of the source. [1.239e-04]
++
+*tracking*:::
+This option logs changes to the estimate of the system's gain or loss rate, and
+any slews made, to a file called _tracking.log_. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
++
+----
+2017-08-22 13:22:36 203.0.113.15     2     -3.541      0.075 -8.621e-06 N \
+            2  2.940e-03 -2.084e-04  1.534e-02  3.472e-04  8.304e-03
+----
++
+The columns are as follows (the quantities in square brackets are the
+values from the example line above) :
++
+. Date [2017-08-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [13:22:36]
+. The IP address of the server or peer to which the local system is synchronised.
+  [203.0.113.15]
+. The stratum of the local system. [2]
+. The local system frequency (in ppm, positive means the local system runs fast
+  of UTC). [-3.541]
+. The error bounds on the frequency (in ppm). [0.075]
+. The estimated local offset at the epoch, which is normally corrected by
+  slewing the local clock (in seconds, positive indicates the clock is fast of
+  UTC). [-8.621e-06]
+. Leap status (_N_ means normal, _+_ means that the last minute of this month
+  has 61 seconds, _-_ means that the last minute of the month has 59 seconds,
+  _?_ means the clock is not currently synchronised.) [N]
+. The number of combined sources. [2]
+. The estimated standard deviation of the combined offset (in seconds).
+  [2.940e-03]
+. The remaining offset correction from the previous update (in seconds,
+  positive means the system clock is slow of UTC). [-2.084e-04]
+. The total of the network path delays to the reference clock to which
+  the local clock is ultimately synchronised (in seconds). [1.534e-02]
+. The total dispersion accumulated through all the servers back to the
+  reference clock to which the local clock is ultimately synchronised
+  (in seconds). [3.472e-04]
+. The maximum estimated error of the system clock in the interval since the
+  previous update (in seconds). It includes the offset, remaining offset
+  correction, root delay, and dispersion from the previous update with the
+  dispersion which accumulated in the interval. [8.304e-03]
++
+*rtc*:::
+This option logs information about the system's real-time clock. An example
+line (which actually appears as a single line in the file) from the _rtc.log_
+file is shown below.
++
+----
+2015-07-22 05:40:50     -0.037360 1       -0.037434\
+          -37.948  12   5  120
+----
++
+The columns are as follows (the quantities in square brackets are the
+values from the example line above):
++
+. Date [2015-07-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [05:40:50]
+. The measured offset between the RTC and the system clock in seconds.
+  Positive indicates that the RTC is fast of the system time [-0.037360].
+. Flag indicating whether the regression has produced valid coefficients.
+  (1 for yes, 0 for no). [1]
+. Offset at the current time predicted by the regression process. A large
+  difference between this value and the measured offset tends to indicate that
+  the measurement is an outlier with a serious measurement error. [-0.037434]
+. The rate at which the RTC is losing or gaining time relative to the system
+  clock. In ppm, with positive indicating that the RTC is gaining time.
+  [-37.948]
+. The number of measurements used in the regression. [12]
+. The number of runs of regression residuals of the same sign. Low values
+  indicate that a straight line is no longer a good model of the measured data
+  and that older measurements should be discarded. [5]
+. The measurement interval used prior to the measurement being made (in
+  seconds). [120]
++
+*refclocks*:::
+This option logs the raw and filtered reference clock measurements to a file
+called _refclocks.log_. An example line (which actually appears as a single
+line in the file) from the log file is shown below.
++
+----
+2009-11-30 14:33:27.000000 PPS2    7 N 1  4.900000e-07 -6.741777e-07  1.000e-06
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2009-11-30]
+. Hour:Minute:Second.Microsecond. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [14:33:27.000000]
+. Reference ID of the reference clock from which the measurement came. [PPS2]
+. Sequence number of driver poll within one polling interval for raw samples,
+  or _-_ for filtered samples. [7]
+. Leap status (_N_ means normal, _+_ means that the last minute of the current
+  month has 61 seconds, _-_ means that the last minute of the month has 59
+  seconds). [N]
+. Flag indicating whether the sample comes from PPS source. (1 for yes,
+  0 for no, or _-_ for filtered sample). [1]
+. Local clock error measured by reference clock driver, or _-_ for filtered sample.
+  [4.900000e-07]
+. Local clock error with applied corrections. Positive indicates that the local
+  clock is slow. [-6.741777e-07]
+. Assumed dispersion of the sample. [1.000e-06]
++
+*tempcomp*:::
+This option logs the temperature measurements and system rate compensations to
+a file called _tempcomp.log_. An example line (which actually appears as a
+single line in the file) from the log file is shown below.
++
+----
+2015-04-19 10:39:48  2.8000e+04  3.6600e-01
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-04-19]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [10:39:48]
+. Temperature read from the sensor. [2.8000e+04]
+. Applied compensation in ppm, positive means the system clock is running
+  faster than it would be without the compensation. [3.6600e-01]
++
+{blank}::
+An example of the directive is:
++
+----
+log measurements statistics tracking
+----
+
+[[logbanner]]*logbanner* _entries_::
+A banner is periodically written to the log files enabled by the <<log,*log*>>
+directive to indicate the meanings of the columns.
++
+The *logbanner* directive specifies after how many entries in the log file
+should be the banner written. The default is 32, and 0 can be used to disable
+it entirely.
+
+[[logchange]]*logchange* _threshold_::
+This directive sets the threshold for the adjustment of the system clock that
+will generate a syslog message. Clock errors detected via NTP packets,
+reference clocks, or timestamps entered via the
+<<chronyc.adoc#settime,*settime*>> command of *chronyc* are logged.
++
+By default, the threshold is 1 second.
++
+An example of the use is:
++
+----
+logchange 0.1
+----
++
+which would cause a syslog message to be generated if a system clock error of over
+0.1 seconds starts to be compensated.
+
+[[logdir]]*logdir* _directory_::
+This directive specifies the directory for writing log files enabled by the
+*log* directive. If the directory does not exist, it will be created
+automatically.
++
+An example of the use of this directive is:
++
+----
+logdir /var/log/chrony
+----
+
+[[mailonchange]]*mailonchange* _email_ _threshold_::
+This directive defines an email address to which mail should be sent if
+*chronyd* applies a correction exceeding a particular threshold to the system
+clock.
++
+An example of the use of this directive is:
++
+----
+mailonchange root@localhost 0.5
+----
++
+This would send a mail message to root if a change of more than 0.5 seconds
+were applied to the system clock.
++
+This directive cannot be used when a system call filter is enabled by the *-F*
+option as the *chronyd* process will not be allowed to fork and execute the
+sendmail binary.
+
+=== Miscellaneous
+
+[[confdir]]*confdir* _directory_...::
+The *confdir* directive includes configuration files with the _.conf_ suffix
+from a directory. The files are included in the lexicographical order of the
+file names.
++
+Multiple directories (up to 10) can be specified with a single *confdir*
+directive. In this case, if multiple directories contain a file with the same
+name, only the first file in the order of the specified directories will be
+included. This enables a fragmented configuration where existing fragments can
+be replaced by adding files to a different directory.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+confdir @SYSCONFDIR@/chrony.d
+----
+
+[[sourcedir]]*sourcedir* _directory_...::
+The *sourcedir* directive is identical to the *confdir* directive, except the
+configuration files have the _.sources_ suffix, they can only specify NTP
+sources (i.e. the *server*, *pool*, and *peer* directives), they are expected
+to have all lines terminated by the newline character, and they can be
+reloaded by the <<chronyc.adoc#reload,*reload sources*>> command in
+*chronyc*. It is particularly useful with dynamic sources like NTP servers
+received from a DHCP server, which can be written to a file specific to the
+network interface by a networking script.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+sourcedir /var/run/chrony-dhcp
+----
+
+[[include]]*include* _pattern_::
+The *include* directive includes a configuration file, or multiple configuration
+files if a wildcard pattern is specified. Unlike with the *confdir* directive,
+the full name of the files needs to be specified and at least one file is
+required to exist.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+include @SYSCONFDIR@/chrony.d/*.conf
+----
+
+[[hwtimestamp]]*hwtimestamp* _interface_ [_option_]...::
+This directive enables hardware timestamping of NTP packets sent to and
+received from the specified network interface. The network interface controller
+(NIC) uses its own clock to accurately timestamp the actual transmissions and
+receptions, avoiding processing and queueing delays in the kernel, network
+driver, and hardware. This can significantly improve the accuracy of the
+timestamps and the measured offset, which is used for synchronisation of the
+system clock. In order to get the best results, both sides receiving and
+sending NTP packets (i.e. server and client, or two peers) need to use HW
+timestamping. If the server or peer supports the interleaved mode, it needs to
+be enabled by the *xleave* option in the <<server,*server*>> or the
+<<peer,*peer*>> directive.
++
+This directive is supported on Linux 3.19 and newer. The NIC must support HW
+timestamping, which can be verified with the *ethtool -T* command. The list of
+capabilities should include _hardware-raw-clock_, _hardware-transmit_, and
+_hardware-receive_. The receive filter _all_, or _ntp_, is necessary for
+timestamping of received NTP packets. Timestamping of packets received on
+bridged and bonded interfaces is supported on Linux 4.13 and newer. If HW
+timestamping does not work for received packets, *chronyd* will use kernel
+receive timestamps instead. Transmit-only HW timestamping can still be useful
+to improve stability of the synchronisation.
++
+*chronyd* does not synchronise the NIC clock. It assumes the clock is running
+free. Multiple instances of *chronyd* can use the same interface with enabled
+HW timestamping. Applications which need HW timestamping with a synchronised
+clock (e.g. a PTP daemon) should use a virtual clock running on top of the
+physical clock created by writing to _/sys/class/ptp/ptpX/n_vclocks_. This
+feature is available on Linux 5.14 and newer.
++
+If the kernel supports software timestamping, it will be enabled for all
+interfaces. The source of timestamps (i.e. hardware, kernel, or daemon) is
+indicated in the _measurements.log_ file if enabled by the <<log,*log
+measurements*>> directive, and the <<chronyc.adoc#ntpdata,*ntpdata*>> report in
+*chronyc*.
++
+This directive can be used multiple times to enable HW timestamping on multiple
+interfaces. If the specified interface is _*_, *chronyd* will try to enable HW
+timestamping on all available interfaces.
++
+The *hwtimestamp* directive has the following options:
++
+*minpoll* _poll_:::
+This option specifies the minimum interval between readings of the NIC clock.
+It's defined as a power of two. It should correspond to the minimum polling
+interval of all NTP sources and the minimum expected polling interval of NTP
+clients. The default value is 0 (1 second) and the minimum value is -6 (1/64th
+of a second).
+*minsamples* _samples_:::
+This option specifies the minimum number of readings kept for tracking of the
+NIC clock. The default value is 2.
+*maxsamples* _samples_:::
+This option specifies the maximum number of readings kept for tracking of the
+NIC clock. The default value is 16.
+*precision* _precision_:::
+This option specifies the assumed precision of reading of the NIC clock. The
+default value is 100e-9 (100 nanoseconds).
+*txcomp* _compensation_:::
+This option specifies the difference in seconds between the actual transmission
+time at the physical layer and the reported transmit timestamp. This value will
+be added to transmit timestamps obtained from the NIC. The default value is 0.
+*rxcomp* _compensation_:::
+This option specifies the difference in seconds between the reported receive
+timestamp and the actual reception time at the physical layer. This value will
+be subtracted from receive timestamps obtained from the NIC. The default value
+is 0.
+*nocrossts*:::
+Some hardware can precisely cross timestamp the NIC clock with the system
+clock. This option disables the use of the cross timestamping.
+*rxfilter* _filter_:::
+This option selects the receive timestamping filter. The _filter_ can be one of
+the following:
+_all_::::
+Enables timestamping of all received packets.
+_ntp_::::
+Enables timestamping of received NTP packets.
+_ptp_::::
+Enables timestamping of received PTP packets.
+_none_::::
+Disables timestamping of received packets.
+{blank}:::
+The most specific filter for timestamping of NTP packets supported by the NIC
+is selected by default. Some NICs can timestamp PTP packets only. By default,
+they will be configured with the _none_ filter and expected to provide hardware
+timestamps for transmitted packets only. Timestamping of PTP packets is useful
+with NTP-over-PTP enabled by the <<chrony.conf.adoc#ptpport,*ptpport*>>
+directive, or when another application is receiving PTP packets on the
+interface. Forcing timestamping of all packets with the _all_ filter could be
+useful if the NIC supported both the _all_ and _ntp_ filters, and it should
+timestamp both NTP and PTP packets, or NTP packets on a different UDP port.
+{blank}::
++
+Examples of the directive are:
++
+----
+hwtimestamp eth0
+hwtimestamp eth1 txcomp 300e-9 rxcomp 645e-9
+hwtimestamp *
+----
+
+[[keyfile]]*keyfile* _file_::
+This directive is used to specify the location of the file containing symmetric
+keys which are shared between NTP servers and clients, or peers, in order to
+authenticate NTP packets with a message authentication code (MAC) using a
+cryptographic hash function or cipher.
++
+The format of the directive is shown in the example below:
++
+----
+keyfile @SYSCONFDIR@/chrony.keys
+----
++
+The argument is simply the name of the file containing the ID-key pairs. The
+format of the file is shown below:
++
+----
+10 tulip
+11 hyacinth
+20 MD5 ASCII:crocus
+25 SHA1 HEX:933F62BE1D604E68A81B557F18CFA200483F5B70
+30 AES128 HEX:7EA62AE64D190114D46D5A082F948EC1
+31 AES256 HEX:37DDCBC67BB902BCB8E995977FAB4D2B5642F5B32EBCEEE421921D97E5CBFE39
+ ...
+----
++
+Each line consists of an ID, optional type, and key.
++
+The ID can be any positive integer in the range 1 through 2^32-1.
++
+The type is a name of a cryptographic hash function or cipher which is used to
+generate and verify the MAC. The default type is *MD5*, which is always
+supported.
+If *chronyd* was built with enabled support for hashing using a crypto library
+(Nettle, GnuTLS, NSS, or LibTomCrypt), the following functions are available: *MD5*,
+*SHA1*, *SHA256*, *SHA384*, *SHA512*. Depending on which library and version is
+*chronyd* using, some of the following hash functions and ciphers may
+also be available:
+*SHA3-224*, *SHA3-256*, *SHA3-384*, *SHA3-512*, *TIGER*, *WHIRLPOOL*, *AES128*,
+*AES256*.
++
+The key can be specified as a string of ASCII characters not containing white
+space with an optional *ASCII:* prefix, or as a hexadecimal number with the
+*HEX:* prefix. The maximum length of the line is 2047 characters.
+If the type is a cipher, the length of the key must match the cipher (i.e. 128
+bits for AES128 and 256 bits for AES256).
++
+It is recommended to use randomly generated keys, specified in the hexadecimal
+format, which are at least 128 bits long (i.e. they have at least 32 characters
+after the *HEX:* prefix). *chronyd* will log a warning to syslog on start if a
+source is specified in the configuration file with a key shorter than 80 bits.
++
+The recommended key types are AES ciphers and SHA3 hash functions. MD5 should
+be avoided unless no other type is supported on the server and client, or
+peers.
++
+The <<chronyc.adoc#keygen,*keygen*>> command of *chronyc* can be used to
+generate random keys for the key file. By default, it generates 160-bit MD5 or
+SHA1 keys.
++
+For security reasons, the file should be readable only by root and the user
+under which *chronyd* is normally running (to allow *chronyd* to re-read the
+file when the <<chronyc.adoc#rekey,*rekey*>> command is issued by *chronyc*).
+
+[[lock_all]]*lock_all*::
+The *lock_all* directive will lock the *chronyd* process into RAM so that it
+will never be paged out. This can result in lower and more consistent latency.
+The directive is supported on Linux, FreeBSD, NetBSD, and illumos.
+
+[[pidfile]]*pidfile* _file_::
+Unless *chronyd* is started with the *-Q* option, it writes its process ID
+(PID) to a file, and checks this file on startup to see if another *chronyd*
+might already be running on the system. By default, the file used is
+_@DEFAULT_PID_FILE@_. The *pidfile* directive allows the name to be changed,
+e.g.:
++
+----
+pidfile /run/chronyd.pid
+----
+
+[[ptpport]]*ptpport* _port_::
+The *ptpport* directive enables *chronyd* to send and receive NTP messages
+contained in PTP event messages (NTP-over-PTP) to enable hardware timestamping
+on NICs which cannot timestamp NTP packets, but can timestamp unicast PTP
+packets. The port recognized by the NICs is 319 (PTP event port). The default
+value is 0 (disabled).
++
+The NTP-over-PTP support is experimental. The protocol and configuration can
+change in future. It should be used only in local networks and expected to work
+only between servers and clients running the same version of *chronyd*.
++
+The PTP port will be open even if *chronyd* is not configured to operate as a
+server or client. The directive does not change the default protocol of
+specified NTP sources. Each NTP source that should use NTP-over-PTP needs to
+be specified with the *port* option set to the PTP port. To actually enable
+hardware timestamping on NICs which can timestamp PTP packets only, the
+*rxfilter* option of the *hwtimestamp* directive needs to be set to _ptp_.
++
+An example of client configuration is:
++
+----
+server foo.example.net minpoll 0 maxpoll 0 xleave port 319
+hwtimestamp * rxfilter ptp
+ptpport 319
+----
+
+[[sched_priority]]*sched_priority* _priority_::
+On Linux, FreeBSD, NetBSD, and illumos, the *sched_priority* directive will
+select the SCHED_FIFO real-time scheduler at the specified priority (which must
+be between 0 and 100). On macOS, this option must have either a value of 0 (the
+default) to disable the thread time constraint policy or 1 for the policy to be
+enabled.
++
+On systems other than macOS, this directive uses the *pthread_setschedparam()*
+system call to instruct the kernel to use the SCHED_FIFO first-in, first-out
+real-time scheduling policy for *chronyd* with the specified priority. This
+means that whenever *chronyd* is ready to run it will run, interrupting
+whatever else is running unless it is a higher priority real-time process. This
+should not impact performance as *chronyd* resource requirements are modest,
+but it should result in lower and more consistent latency since *chronyd* will
+not need to wait for the scheduler to get around to running it. You should not
+use this unless you really need it. The *pthread_setschedparam(3)* man page has
+more details.
++
+On macOS, this directive uses the *thread_policy_set()* kernel call to
+specify real-time scheduling. As noted above, you should not use this directive
+unless you really need it.
+
+[[user]]*user* _user_::
+The *user* directive sets the name of the system user to which *chronyd* will
+switch after start in order to drop root privileges.
++
+On Linux, *chronyd* needs to be compiled with support for the *libcap* library.
+On macOS, FreeBSD, NetBSD and illumos *chronyd* forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
++
+The compiled-in default value is _@DEFAULT_USER@_.
+
+[[examples]]
+== EXAMPLES
+
+=== NTP client with permanent connection to NTP servers
+
+This section shows how to configure *chronyd* for computers that are connected
+to the Internet (or to any network containing true NTP servers which ultimately
+derive their time from a reference clock) permanently or most of the time.
+
+To operate in this mode, you will need to know the names of the NTP servers
+you want to use. You might be able to find names of suitable servers by one of
+the following methods:
+
+* Your institution might already operate servers on its network.
+  Contact your system administrator to find out.
+* Your ISP probably has one or more NTP servers available for its
+  customers.
+* Somewhere under the NTP homepage there is a list of public
+  stratum 1 and stratum 2 servers. You should find one or more servers that are
+  near to you. Check that their access policy allows you to use their
+  facilities.
+* Use public servers from the https://www.pool.ntp.org/[pool.ntp.org] project.
+
+Assuming that your NTP servers are called _foo.example.net_, _bar.example.net_
+and _baz.example.net_, your _chrony.conf_ file could contain as a minimum:
+
+----
+server foo.example.net
+server bar.example.net
+server baz.example.net
+----
+
+However, you will probably want to include some of the other directives. The
+<<driftfile,*driftfile*>>, <<makestep,*makestep*>> and <<rtcsync,*rtcsync*>>
+might be particularly useful. Also, the *iburst* option of the
+<<server,*server*>> directive is useful to speed up the initial
+synchronisation. The smallest useful configuration file would look something
+like:
+
+----
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+When using a pool of NTP servers (one name is used for multiple servers which
+might change over time), it is better to specify them with the <<pool,*pool*>>
+directive instead of multiple *server* directives. The configuration file could
+in this case look like:
+
+----
+pool pool.ntp.org iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+If the servers (or pool) support the Network Time Security (NTS)
+authentication mechanism and *chronyd* is compiled with NTS support, the *nts*
+option will enable a secure synchronisation to the servers. The configuration
+file could look like:
+
+----
+server foo.example.net iburst nts
+server bar.example.net iburst nts
+server baz.example.net iburst nts
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+=== NTP client with infrequent connection to NTP servers
+
+This section shows how to configure *chronyd* for computers that have
+occasional connections to NTP servers. In this case, you will need some
+additional configuration to tell *chronyd* when the connection goes up and
+down. This saves the program from continuously trying to poll the servers when
+they are inaccessible.
+
+Again, assuming that your NTP servers are called _foo.example.net_,
+_bar.example.net_ and _baz.example.net_, your _chrony.conf_ file would now
+contain:
+
+----
+server foo.example.net offline
+server bar.example.net offline
+server baz.example.net offline
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+The *offline* keyword indicates that the servers start in an offline state, and
+that they should not be contacted until *chronyd* receives notification from
+*chronyc* that the link to the Internet is present. To tell *chronyd* when to
+start and finish sampling the servers, the <<chronyc.adoc#online,*online*>> and
+<<chronyc.adoc#offline,*offline*>> commands of *chronyc* need to be used.
+
+To give an example of their use, assuming that *pppd* is the program being
+used to connect to the Internet and that *chronyc* has been installed at
+_@BINDIR@/chronyc_, the script _/etc/ppp/ip-up_ would include:
+
+----
+@BINDIR@/chronyc online
+----
+
+and the script _/etc/ppp/ip-down_ would include:
+
+----
+@BINDIR@/chronyc offline
+----
+
+*chronyd*'s polling of the servers would now only occur whilst the machine is
+actually connected to the Internet.
+
+=== Isolated networks
+
+This section shows how to configure *chronyd* for computers that never have
+network connectivity to any computer which ultimately derives its time from a
+reference clock.
+
+In this situation, one computer is selected to be the primary timeserver. The
+other computers are either direct clients of the server, or clients of clients.
+
+The <<local,*local*>> directive enables a local reference mode, which allows
+*chronyd* to appear synchronised even when it is not.
+
+The rate value in the server's drift file needs to be set to the average rate
+at which the server gains or loses time. *chronyd* includes support for this,
+in the form of the <<manual,*manual*>> directive and the
+<<chronyc.adoc#settime,*settime*>> command in the *chronyc* program.
+
+If the server is rebooted, *chronyd* can re-read the drift rate from the drift
+file. However, the server has no accurate estimate of the current time. To get
+around this, the system can be configured so that the server can initially set
+itself to a '`majority-vote`' of selected clients' times; this allows the
+clients to '`flywheel`' the server while it is rebooting.
+
+The <<smoothtime,*smoothtime*>> directive is useful when the clocks of the
+clients need to stay close together when the local time is adjusted by the
+<<chronyc.adoc#settime,*settime*>> command. The smoothing process needs to be
+activated by the <<chronyc.adoc#smoothtime,*smoothtime activate*>> command when
+the local time is ready to be served. After that point, any adjustments will be
+smoothed out.
+
+A typical configuration file for the server (called _ntp.local_) might be
+(assuming the clients and the server are in the _192.168.165.x_ subnet):
+
+----
+initstepslew 1 client1 client3 client6
+driftfile @CHRONYVARDIR@/drift
+local stratum 8
+manual
+allow 192.168.165.0/24
+smoothtime 400 0.01
+rtcsync
+----
+
+For the clients that have to resynchronise the server when it restarts,
+the configuration file might be:
+
+----
+server ntp.local iburst
+driftfile @CHRONYVARDIR@/drift
+allow 192.168.165.0/24
+makestep 1.0 3
+rtcsync
+----
+
+The rest of the clients would be the same, except that the *allow* directive is
+not required.
+
+If there is no suitable computer to be designated as the primary server, or
+there is a requirement to keep the clients synchronised even when it fails, the
+*orphan* option of the *local* directive enables a special mode where the
+server is selected from multiple computers automatically. They all need to use
+the same *local* configuration and poll one another. The server with the
+smallest reference ID (which is based on its IP address) will take the role of
+the primary server and others will be synchronised to it. When it fails, the
+server with the second smallest reference ID will take over and so on.
+
+A configuration file for the first server might be (assuming there are three
+servers called _ntp1.local_, _ntp2.local_, and _ntp3.local_):
+
+----
+initstepslew 1 ntp2.local ntp3.local
+server ntp2.local
+server ntp3.local
+driftfile @CHRONYVARDIR@/drift
+local stratum 8 orphan
+manual
+allow 192.168.165.0/24
+rtcsync
+----
+
+The other servers would be the same, except the hostnames in the *initstepslew*
+and *server* directives would be modified to specify the other servers. Their
+clients might be configured to poll all three servers.
+
+=== RTC tracking
+
+This section considers a computer which has occasional connections to the
+Internet and is turned off between '`sessions`'. In this case, *chronyd* relies
+on the computer's RTC to maintain the time between the periods when it is
+powered up. It assumes that Linux is run exclusively on the computer. Dual-boot
+systems might work; it depends what (if anything) the other system does to the
+RTC. On 2.6 and later kernels, if your motherboard has a HPET, you will need to
+enable the *HPET_EMULATE_RTC* option in your kernel configuration. Otherwise,
+*chronyd* will not be able to interact with the RTC device and will give up
+using it.
+
+When the computer is connected to the Internet, *chronyd* has access to
+external NTP servers which it makes measurements from. These measurements are
+saved, and straight-line fits are performed on them to provide an estimate of
+the computer's time error and rate of gaining or losing time.
+
+When the computer is taken offline from the Internet, the best estimate of the
+gain or loss rate is used to free-run the computer until it next goes online.
+
+Whilst the computer is running, *chronyd* makes measurements of the RTC (via
+the _/dev/rtc_ interface, which must be compiled into the kernel). An estimate
+is made of the RTC error at a particular RTC second, and the rate at which the
+RTC gains or loses time relative to true time.
+
+When the computer is powered down, the measurement histories for all the NTP
+servers are saved to files, and the RTC tracking information is also
+saved to a file (if the <<rtcfile,*rtcfile*>> directive has been specified).
+These pieces of information are also saved if the <<chronyc.adoc#dump,*dump*>>
+and <<chronyc.adoc#writertc,*writertc*>> commands respectively are issued
+through *chronyc*.
+
+When the computer is rebooted, *chronyd* reads the current RTC time and the RTC
+information saved at the last shutdown. This information is used to set the
+system clock to the best estimate of what its time would have been now, had it
+been left running continuously. The measurement histories for the servers are
+then reloaded.
+
+The next time the computer goes online, the previous sessions' measurements can
+contribute to the line-fitting process, which gives a much better estimate of
+the computer's gain or loss rate.
+
+One problem with saving the measurements and RTC data when the machine is shut
+down is what happens if there is a power failure; the most recent data will not
+be saved. Although *chronyd* is robust enough to cope with this, some
+performance might be lost. (The main danger arises if the RTC has been changed
+during the session, with the *trimrtc* command in *chronyc*. Because of this,
+*trimrtc* will make sure that a meaningful RTC file is saved after the
+change is completed).
+
+The easiest protection against power failure is to put the *dump* and
+*writertc* commands in the same place as the *offline* command is issued to
+take *chronyd* offline; because *chronyd* free-runs between online sessions, no
+parameters will change significantly between going offline from the Internet
+and any power failure.
+
+A final point regards computers which are left running for extended periods and
+where it is desired to spin down the hard disc when it is not in use (e.g. when
+not accessed for 15 minutes). *chronyd* has been planned so it supports such
+operation; this is the reason why the RTC tracking parameters are not saved to
+disc after every update, but only when the user requests such a write, or
+during the shutdown sequence. The only other facility that will generate
+periodic writes to the disc is the *log rtc* facility in the configuration
+file; this option should not be used if you want your disc to spin down.
+
+To illustrate how a computer might be configured for this case, example
+configuration files are shown.
+
+For the _chrony.conf_ file, the following can be used as an example.
+
+----
+server foo.example.net maxdelay 0.4 offline
+server bar.example.net maxdelay 0.4 offline
+server baz.example.net maxdelay 0.4 offline
+logdir /var/log/chrony
+log statistics measurements tracking
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+maxupdateskew 100.0
+dumpdir @CHRONYVARDIR@
+rtcfile @CHRONYVARDIR@/rtc
+----
+
+*pppd* is used for connecting to the Internet. This runs two scripts
+_/etc/ppp/ip-up_ and _/etc/ppp/ip-down_ when the link goes online and offline
+respectively.
+
+The relevant part of the _/etc/ppp/ip-up_ file is:
+
+----
+@BINDIR@/chronyc online
+----
+
+and the relevant part of the _/etc/ppp/ip-down_ script is:
+
+----
+@BINDIR@/chronyc -m offline dump writertc
+----
+
+*chronyd* is started during the boot sequence with the *-r* and *-s* options.
+It might need to be started before any software that depends on the system clock
+not jumping or moving backwards, depending on the directives in *chronyd*'s
+configuration file.
+
+For the system shutdown, *chronyd* should receive a SIGTERM several seconds
+before the final SIGKILL; the SIGTERM causes the measurement histories and RTC
+information to be saved.
+
+=== Public NTP server
+
+*chronyd* can be configured to operate as a public NTP server, e.g. to join the
+https://www.pool.ntp.org/en/join.html[pool.ntp.org] project. The configuration
+is similar to the NTP client with permanent connection, except it needs to
+allow client access from all addresses. It is recommended to find at least four
+good servers (e.g. from the pool, or on the NTP homepage). If the server has a
+hardware reference clock (e.g. a GPS receiver), it can be specified by the
+<<refclock,*refclock*>> directive.
+
+The amount of memory used for logging client accesses can be increased in order
+to enable clients to use the interleaved mode even when the server has a large
+number of clients, and better support rate limiting if it is enabled by the
+<<ratelimit,*ratelimit*>> directive. The system timezone database, if it is
+kept up to date and includes the _right/UTC_ timezone, can be used as a
+reliable source to determine when a leap second will be applied to UTC. The
+*-r* option with the <<dumpdir,*dumpdir*>> directive shortens the time in which
+*chronyd* will not be able to serve time to its clients when it needs to be
+restarted (e.g. after upgrading to a newer version, or a change in the
+configuration).
+
+The configuration file could look like:
+
+----
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+server qux.example.net iburst
+makestep 1.0 3
+rtcsync
+allow
+clientloglimit 100000000
+leapsectz right/UTC
+driftfile @CHRONYVARDIR@/drift
+dumpdir @CHRONYRUNDIR@
+----
+
+== SEE ALSO
+
+<<chronyc.adoc#,*chronyc(1)*>>, <<chronyd.adoc#,*chronyd(8)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony.tuxfamily.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chrony.conf.man.in b/doc/chrony.conf.man.in
new file mode 100644
index 0000000..1a51b24
--- /dev/null
+++ b/doc/chrony.conf.man.in
@@ -0,0 +1,4894 @@
+'\" t
+.\"     Title: chrony.conf
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.15
+.\"      Date: 2022-08-29
+.\"    Manual: Configuration Files
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONY.CONF" "5" "2022-08-29" "chrony @CHRONY_VERSION@" "Configuration Files"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chrony.conf \- chronyd configuration file
+.SH "SYNOPSIS"
+.sp
+\fBchrony.conf\fP
+.SH "DESCRIPTION"
+.sp
+This file configures the \fBchronyd\fP daemon. The compiled\-in location is
+\fI@SYSCONFDIR@/chrony.conf\fP. Other locations can be specified on the
+\fBchronyd\fP command line with the \fB\-f\fP option.
+.sp
+Each directive in the configuration file is placed on a separate line. The
+following sections describe each of the directives in turn. The directives are
+not case\-sensitive. Generally, the directives can occur in any order in the file
+and if a directive is specified multiple times, only the last one will be
+effective. Exceptions are noted in the descriptions.
+.sp
+The configuration directives can also be specified directly on the \fBchronyd\fP
+command line. In this case each argument is parsed as a new line and the
+configuration file is ignored.
+.sp
+While the number of supported directives is large, only a few of them are
+typically needed. See the \fBEXAMPLES\fP section for configuration in
+typical operating scenarios.
+.sp
+The configuration file might contain comment lines. A comment line is any line
+that starts with zero or more spaces followed by any one of the following
+characters: \fB!\fP, \fB;\fP, \fB#\fP, \fB%\fP. Any line with this format will be ignored.
+.SH "DIRECTIVES"
+.SS "Time sources"
+.sp
+\fBserver\fP \fIhostname\fP [\fIoption\fP]...
+.RS 4
+The \fBserver\fP directive specifies an NTP server which can be used as a time
+source. The client\-server relationship is strictly hierarchical: a client might
+synchronise its system time to that of the server, but the server\(cqs system time
+will never be influenced by that of a client.
+.sp
+The server can be specified by its hostname or IP address. If the hostname cannot
+be resolved on start, \fBchronyd\fP will try it again in increasing intervals, and
+also when the \fBonline\fP command is issued in \fBchronyc\fP.
+.sp
+The DNS record can change over time. The used address will be replaced with a
+newly resolved address when the server becomes unreachable (i.e. no valid
+response to last 8 requests), unsynchronised, a falseticker (i.e. does not
+agree with a majority of other sources), or the root distance is too large (the
+limit can be configured by the \fBmaxdistance\fP directive). The
+automatic replacement happens at most once per 30 minutes. It can also be
+triggered manually for all sources by the \fBrefresh\fP
+command in \fBchronyc\fP.
+.sp
+This directive can be used multiple times to specify multiple servers.
+.sp
+The directive supports the following options:
+.sp
+\fBminpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the minimum interval between requests sent to the server
+as a power of 2 in seconds. For example, \fBminpoll 5\fP would mean that the
+polling interval should not drop below 32 seconds. The default is 6 (64
+seconds), the minimum is \-7 (1/128th of a second), and the maximum is 24 (6
+months). Note that intervals shorter than 6 (64 seconds) should generally not
+be used with public servers on the Internet, because it might be considered
+abuse. A sub\-second interval will be enabled only when the server is reachable
+and the round\-trip delay is shorter than 10 milliseconds, i.e. the server
+should be in a local network.
+.RE
+.sp
+\fBmaxpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the maximum interval between requests sent to the server
+as a power of 2 in seconds. For example, \fBmaxpoll 9\fP indicates that the polling
+interval should stay at or below 9 (512 seconds). The default is 10 (1024
+seconds), the minimum is \-7 (1/128th of a second), and the maximum is 24 (6
+months).
+.RE
+.sp
+\fBiburst\fP
+.RS 4
+With this option, \fBchronyd\fP will start with a burst of 4\-8 requests in order to
+make the first update of the clock sooner. It will also repeat the burst every
+time the source is switched from the offline state to online with the
+\fBonline\fP command in \fBchronyc\fP.
+.RE
+.sp
+\fBburst\fP
+.RS 4
+With this option, \fBchronyd\fP will send a burst of up to 4 requests when it
+cannot get a good measurement from the
+server. The number of requests in the burst is limited by the current polling
+interval to keep the average interval at or above the minimum interval, i.e.
+the current interval needs to be at least two times longer than the minimum
+interval in order to allow a burst with two requests.
+.RE
+.sp
+\fBkey\fP \fIID\fP
+.RS 4
+The NTP protocol supports a message authentication code (MAC) to prevent
+computers having their system time upset by rogue packets being sent to them.
+The MAC is generated as a function of a key specified in the key file,
+which is specified by the \fBkeyfile\fP directive.
+.sp
+The \fBkey\fP option specifies which key (with an ID in the range 1 through 2^32\-1)
+should \fBchronyd\fP use to authenticate requests sent to the server and verify its
+responses. The server must have the same key for this number configured,
+otherwise no relationship between the computers will be possible.
+.sp
+If the server is running \fBntpd\fP and the output size of the hash function used
+by the key is longer than 160 bits (e.g. SHA256), the \fBversion\fP option needs to
+be set to 4 for compatibility.
+.RE
+.sp
+\fBnts\fP
+.RS 4
+This option enables authentication using the Network Time Security (NTS)
+mechanism. Unlike with the \fBkey\fP option, the server and client do not need to
+share a key in a key file. NTS has a Key Establishment (NTS\-KE) protocol using
+the Transport Layer Security (TLS) protocol to get the keys and cookies
+required by NTS for authentication of NTP packets.
+.RE
+.sp
+\fBcertset\fP \fIID\fP
+.RS 4
+This option specifies which set of trusted certificates should be used to verify
+the server\(cqs certificate when the \fBnts\fP option is enabled. Sets of certificates
+can be specified with the \fBntstrustedcerts\fP directive. The
+default set is 0, which by default contains certificates of the system\(cqs
+default trusted certificate authorities.
+.RE
+.sp
+\fBmaxdelay\fP \fIdelay\fP
+.RS 4
+\fBchronyd\fP uses the network round\-trip delay to the server to determine how
+accurate a particular measurement is likely to be. Long round\-trip delays
+indicate that the request, or the response, or both were delayed. If only one
+of the messages was delayed the measurement error is likely to be substantial.
+.sp
+For small variations in the round\-trip delay, \fBchronyd\fP uses a weighting scheme
+when processing the measurements. However, beyond a certain level of delay the
+measurements are likely to be so corrupted as to be useless. (This is
+particularly so on wireless networks and other slow links, where a long delay
+probably indicates a highly asymmetric delay caused by the response waiting
+behind a lot of packets related to a download of some sort).
+.sp
+If the user knows that round trip delays above a certain level should cause the
+measurement to be ignored, this level can be defined with the \fBmaxdelay\fP
+option. For example, \fBmaxdelay 0.3\fP would indicate that measurements with a
+round\-trip delay greater than 0.3 seconds should be ignored. The default value
+is 3 seconds and the maximum value is 1000 seconds.
+.RE
+.sp
+\fBmaxdelayratio\fP \fIratio\fP
+.RS 4
+This option is similar to the \fBmaxdelay\fP option above. \fBchronyd\fP keeps a record
+of the minimum round\-trip delay amongst the previous measurements that it has
+buffered. If a measurement has a round\-trip delay that is greater than the
+specified ratio times the minimum delay, it will be rejected. By default, this
+test is disabled.
+.RE
+.sp
+\fBmaxdelaydevratio\fP \fIratio\fP
+.RS 4
+If a measurement has a ratio of the increase in the round\-trip delay from the
+minimum delay amongst the previous measurements to the standard deviation of
+the previous measurements that is greater than the specified ratio, it will be
+rejected. The default is 10.0.
+.RE
+.sp
+\fBmaxdelayquant\fP \fIp\fP
+.RS 4
+This option disables the \fBmaxdelaydevratio\fP test and specifies the maximum
+acceptable delay as a quantile of the round\-trip delay instead of a function of
+the minimum delay amongst the buffered measurements. If a measurement has a
+round\-trip delay that is greater than a long\-term estimate of the \fIp\fP\-quantile,
+it will be rejected.
+.sp
+The specified \fIp\fP value should be between 0.05 and 0.95. For example,
+\fBmaxdelayquant 0.2\fP would indicate that only measurements with the lowest 20
+percent of round\-trip delays should be accepted. Note that it can take many
+measurements for the estimated quantile to reach the expected value. This
+option is intended for synchronisation in mostly static local networks with
+very short polling intervals and possibly combined with the \fBfilter\fP option.
+By default, this test is disabled in favour of the \fBmaxdelaydevratio\fP test.
+.RE
+.sp
+\fBmindelay\fP \fIdelay\fP
+.RS 4
+This option specifies a fixed minimum round\-trip delay to be used instead of
+the minimum amongst the previous measurements. This can be useful in networks
+with static configuration to improve the stability of corrections for
+asymmetric jitter, weighting of the measurements, and the \fBmaxdelayratio\fP and
+\fBmaxdelaydevratio\fP tests. The value should be set accurately in order to have a
+positive effect on the synchronisation.
+.RE
+.sp
+\fBasymmetry\fP \fIratio\fP
+.RS 4
+This option specifies the asymmetry of the network jitter on the path to the
+source, which is used to correct the measured offset according to the delay.
+The asymmetry can be between \-0.5 and +0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent from
+the source back. By default, \fBchronyd\fP estimates the asymmetry automatically.
+.RE
+.sp
+\fBoffset\fP \fIoffset\fP
+.RS 4
+This option specifies a correction (in seconds) which will be applied to
+offsets measured with this source. It\(cqs particularly useful to compensate for a
+known asymmetry in network delay or timestamping errors. For example, if
+packets sent to the source were on average delayed by 100 microseconds more
+than packets sent from the source back, the correction would be \-0.00005 (\-50
+microseconds). The default is 0.0.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+Set the minimum number of samples kept for this source. This overrides the
+\fBminsamples\fP directive.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+Set the maximum number of samples kept for this source. This overrides the
+\fBmaxsamples\fP directive.
+.RE
+.sp
+\fBfilter\fP \fIpolls\fP
+.RS 4
+This option enables a median filter to reduce noise in NTP measurements. The
+filter will process samples collected in the specified number of polls
+into a single sample. It is intended to be used with very short polling
+intervals in local networks where it is acceptable to generate a lot of NTP
+traffic.
+.RE
+.sp
+\fBoffline\fP
+.RS 4
+If the server will not be reachable when \fBchronyd\fP is started, the \fBoffline\fP
+option can be specified. \fBchronyd\fP will not try to poll the server until it is
+enabled to do so (by using the \fBonline\fP command in
+\fBchronyc\fP).
+.RE
+.sp
+\fBauto_offline\fP
+.RS 4
+With this option, the server will be assumed to have gone offline when sending
+a request fails, e.g. due to a missing route to the network. This option avoids
+the need to run the \fBoffline\fP command from \fBchronyc\fP
+when disconnecting the network link. (It will still be necessary to use the
+\fBonline\fP command when the link has been established, to
+enable measurements to start.)
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+Prefer this source over sources without the \fBprefer\fP option.
+.RE
+.sp
+\fBnoselect\fP
+.RS 4
+Never select this source. This is particularly useful for monitoring.
+.RE
+.sp
+\fBtrust\fP
+.RS 4
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+.RE
+.sp
+\fBrequire\fP
+.RS 4
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the \fBtrust\fP option this might be useful to allow a trusted
+authenticated source to be safely combined with unauthenticated sources in
+order to improve the accuracy of the clock. They can be selected and used for
+synchronisation only if they agree with the trusted and required source.
+.RE
+.sp
+\fBxleave\fP
+.RS 4
+This option enables the interleaved mode of NTP. It enables the server to
+respond with more accurate transmit timestamps (e.g. kernel or hardware
+timestamps), which cannot be contained in the transmitted packet itself and
+need to refer to a previous packet instead. This can significantly improve the
+accuracy and stability of the measurements.
+.sp
+The interleaved mode is compatible with servers that support only the basic
+mode. Note that even
+servers that support the interleaved mode might respond in the basic mode as
+the interleaved mode requires the servers to keep some state for each client
+and the state might be dropped when there are too many clients (e.g.
+\fBclientloglimit\fP is too small), or it might be overwritten
+by other clients that have the same IP address (e.g. computers behind NAT or
+someone sending requests with a spoofed source address).
+.sp
+The \fBxleave\fP option can be combined with the \fBpresend\fP option in order to
+shorten the interval in which the server has to keep the state to be able to
+respond in the interleaved mode.
+.RE
+.sp
+\fBpolltarget\fP \fItarget\fP
+.RS 4
+Target number of measurements to use for the regression algorithm which
+\fBchronyd\fP will try to maintain by adjusting the polling interval between
+\fBminpoll\fP and \fBmaxpoll\fP. A higher target makes \fBchronyd\fP prefer shorter polling
+intervals. The default is 8 and a useful range is from 6 to 60.
+.RE
+.sp
+\fBport\fP \fIport\fP
+.RS 4
+This option allows the UDP port on which the server understands NTP requests to
+be specified. For normal servers this option should not be required (the
+default is 123, the standard NTP port).
+.RE
+.sp
+\fBntsport\fP \fIport\fP
+.RS 4
+This option specifies the TCP port on which the server is listening for NTS\-KE
+connections when the \fBnts\fP option is enabled. The default is 4460.
+.RE
+.sp
+\fBpresend\fP \fIpoll\fP
+.RS 4
+If the timing measurements being made by \fBchronyd\fP are the only network data
+passing between two computers, you might find that some measurements are badly
+skewed due to either the client or the server having to do an ARP lookup on the
+other party prior to transmitting a packet. This is more of a problem with long
+sampling intervals, which might be similar in duration to the lifetime of entries
+in the ARP caches of the machines.
+.sp
+In order to avoid this problem, the \fBpresend\fP option can be used. It takes a
+single integer argument, which is the smallest polling interval for which an
+extra pair of NTP packets will be exchanged between the client and the server
+prior to the actual measurement. For example, with the following option
+included in a \fBserver\fP directive:
+.sp
+.if n .RS 4
+.nf
+.fam C
+presend 9
+.fam
+.fi
+.if n .RE
+.sp
+when the polling interval is 512 seconds or more, an extra NTP client packet
+will be sent to the server a short time (2 seconds) before making the actual
+measurement.
+.sp
+If the \fBpresend\fP option is used together with the \fBxleave\fP option, \fBchronyd\fP
+will send two extra packets instead of one.
+.RE
+.sp
+\fBminstratum\fP \fIstratum\fP
+.RS 4
+When the synchronisation source is selected from available sources, sources
+with lower stratum are normally slightly preferred. This option can be used to
+increase stratum of the source to the specified minimum, so \fBchronyd\fP will
+avoid selecting that source. This is useful with low\-stratum sources that are
+known to be unreliable or inaccurate and which should be used only when other
+sources are unreachable.
+.RE
+.sp
+\fBversion\fP \fIversion\fP
+.RS 4
+This option sets the NTP version of packets sent to the server. This can be
+useful when the server runs an old NTP implementation that does not respond to
+requests using a newer version. The default version depends on other options.
+If the \fBextfield\fP or \fBxleave\fP option is used, the default version is 4. If
+those options are not used and the \fBkey\fP option specifies a key using a hash
+function with output size longer than 160 bits (e.g. SHA256), the default
+version is 3 for compatibility with older \fBchronyd\fP servers. In other cases,
+the default version is 4.
+.RE
+.sp
+\fBcopy\fP
+.RS 4
+This option specifies that the server and client are closely related, their
+configuration does not allow a synchronisation loop to form between them, and
+the client is allowed to assume the reference ID and stratum of the server.
+This is useful when multiple instances of \f(CRchronyd\fP are running on one computer
+(e.g. for security or performance reasons), one primarily operating as a client
+to synchronise the system clock and other instances started with the \fB\-x\fP
+option to operate as NTP servers for other computers with their NTP clocks
+synchronised to the first instance.
+.RE
+.sp
+\fBextfield\fP \fItype\fP
+.RS 4
+This option enables an NTPv4 extension field specified by its type as a
+hexadecimal number. It will be included in requests sent to the server and
+processed in received responses if the server supports it. Note that some
+server implementations do not respond to requests containing an unknown
+extension field (\fBchronyd\fP as a server responded to such requests since
+version 2.0).
+.sp
+The following extension field can be enabled by this option:
+.sp
+\fIF323\fP
+.RS 4
+This is an experimental extension field for some improvements that were
+proposed for the next version of the NTP protocol (NTPv5). The field contains
+root delay and dispersion in higher resolution and a monotonic receive
+timestamp, which enables a frequency transfer between the server and client. It
+can significantly improve stability of the synchronization. Generally, it
+should be expected to work only between servers and clients running the same
+version of \fBchronyd\fP.
+.RE
+.RE
+.sp
+
+.RS 4
+.RE
+.RE
+.sp
+\fBpool\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The syntax of this directive is similar to that for the \fBserver\fP
+directive, except that it is used to specify a pool of NTP servers rather than
+a single NTP server. The pool name is expected to resolve to multiple addresses
+which might change over time.
+.sp
+This directive can be used multiple times to specify multiple pools.
+.sp
+All options valid in the \fBserver\fP directive can be used in this
+directive too. There is one option specific to the \fBpool\fP directive:
+.sp
+\fBmaxsources\fP \fIsources\fP
+.RS 4
+This option sets the desired number of sources to be used from the pool.
+\fBchronyd\fP will repeatedly try to resolve the name until it gets this number of
+sources responding to requests. The default value is 4 and the maximum value is
+16.
+.sp
+An example of the \fBpool\fP directive is
+.sp
+.if n .RS 4
+.nf
+.fam C
+pool pool.ntp.org iburst maxsources 3
+.fam
+.fi
+.if n .RE
+.RE
+.RE
+.sp
+\fBpeer\fP \fIhostname\fP [\fIoption\fP]...
+.RS 4
+The syntax of this directive is identical to that for the \fBserver\fP
+directive, except that it specifies a symmetric association with an NTP peer
+instead of a client/server association with an NTP server. A single symmetric
+association allows the peers to be both servers and clients to each other. This
+is mainly useful when the NTP implementation of the peer (e.g. \fBntpd\fP) supports
+ephemeral symmetric associations and does not need to be configured with an
+address of this host. \fBchronyd\fP does not support ephemeral associations.
+.sp
+This directive can be used multiple times to specify multiple peers.
+.sp
+The following options of the \fBserver\fP directive do not work in the \fBpeer\fP
+directive: \fBiburst\fP, \fBburst\fP, \fBnts\fP, \fBpresend\fP, \fBcopy\fP.
+.sp
+When using the \fBxleave\fP option, both peers must support and have enabled the
+interleaved mode, otherwise the synchronisation will work in one direction
+only.
+When a key is specified by the \fBkey\fP option to enable authentication, both
+peers must use the same key and the same key number.
+.sp
+Note that the symmetric mode is less secure than the client/server mode. A
+denial\-of\-service attack is possible on unauthenticated symmetric associations,
+i.e. when the peer was specified without the \fBkey\fP option. An attacker who does
+not see network traffic between two hosts, but knows that they are peering with
+each other, can periodically send them unauthenticated packets with spoofed
+source addresses in order to disrupt their NTP state and prevent them from
+synchronising to each other. When the association is authenticated, an attacker
+who does see the network traffic, but cannot prevent the packets from reaching
+the other host, can still disrupt the state by replaying old packets. The
+attacker has effectively the same power as a man\-in\-the\-middle attacker. A
+partial protection against this attack is implemented in \fBchronyd\fP, which can
+protect the peers if they are using the same polling interval and they never
+sent an authenticated packet with a timestamp from future, but it should not be
+relied on as it is difficult to ensure the conditions are met. If two hosts
+should be able to synchronise to each other in both directions, it is
+recommended to use two separate client/server associations (specified by the
+\fBserver\fP directive on both hosts) instead.
+.RE
+.sp
+\fBinitstepslew\fP \fIstep\-threshold\fP [\fIhostname\fP]...
+.RS 4
+(This directive is deprecated in favour of the \fBmakestep\fP
+directive.)
+.sp
+The purpose of the \fBinitstepslew\fP directive is to allow \fBchronyd\fP to make a
+rapid measurement of the system clock error at boot time, and to correct the
+system clock by stepping before normal operation begins. Since this would
+normally be performed only at an appropriate point in the system boot sequence,
+no other software should be adversely affected by the step.
+.sp
+If the correction required is less than a specified threshold, a slew is used
+instead. This makes it safer to restart \fBchronyd\fP whilst the system is in
+normal operation.
+.sp
+The \fBinitstepslew\fP directive takes a threshold and a list of NTP servers as
+arguments. Each of the servers is rapidly polled several times, and a majority
+voting mechanism used to find the most likely range of system clock error that
+is present. A step or slew is applied to the system clock to correct this
+error. \fBchronyd\fP then enters its normal operating mode.
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 30 foo.example.net bar.example.net baz.example.net
+.fam
+.fi
+.if n .RE
+.sp
+where 3 NTP servers are used to make the measurement. The \fI30\fP indicates that
+if the system\(cqs error is found to be 30 seconds or less, a slew will be used to
+correct it; if the error is above 30 seconds, a step will be used.
+.sp
+The \fBinitstepslew\fP directive can also be used in an isolated LAN environment,
+where the clocks are set manually. The most stable computer is chosen as the
+primary server and the other computers are its clients. If each of the clients
+is configured with the \fBlocal\fP directive, the server can be set up
+with an \fBinitstepslew\fP directive which references some or all of the clients.
+Then, if the server machine has to be rebooted, the clients can be relied on to
+act analogously to a flywheel and preserve the time for a short period while
+the server completes its reboot.
+.sp
+The \fBinitstepslew\fP directive is functionally similar to a combination of the
+\fBmakestep\fP and \fBserver\fP directives with the \fBiburst\fP
+option. The main difference is that the \fBinitstepslew\fP servers are used only
+before normal operation begins and that the foreground \fBchronyd\fP process waits
+for \fBinitstepslew\fP to finish before exiting. This prevent programs started in
+the boot sequence after \fBchronyd\fP from reading the clock before it has been
+stepped. With the \fBmakestep\fP directive, the
+\fBwaitsync\fP command of \fBchronyc\fP can be used instead.
+.RE
+.sp
+\fBrefclock\fP \fIdriver\fP \fIparameter\fP[:\fIoption\fP]... [\fIoption\fP]...
+.RS 4
+The \fBrefclock\fP directive specifies a hardware reference clock to be used as a
+time source. It has two mandatory parameters, a driver name and a
+driver\-specific parameter. The two parameters are followed by zero or more
+refclock options. Some drivers have special options, which can be appended to
+the driver\-specific parameter using the \fB:\fP character.
+.sp
+This directive can be used multiple times to specify multiple reference clocks.
+.sp
+There are four drivers included in \fBchronyd\fP:
+.sp
+\fBPPS\fP
+.RS 4
+Driver for the kernel PPS (pulse per second) API. The parameter is the path to
+the PPS device (typically \fI/dev/pps?\fP). As PPS refclocks do not supply full
+time, another time source (e.g. NTP server or non\-PPS refclock) is needed to
+complete samples from the PPS refclock. An alternative is to enable the
+\fBlocal\fP directive to allow synchronisation with some unknown but
+constant offset. The driver supports the following option:
+.sp
+\fBclear\fP
+.RS 4
+By default, the PPS refclock uses assert events (rising edge) for
+synchronisation. With this option, it will use clear events (falling edge)
+instead.
+.RE
+.RE
+.sp
+
+.RS 4
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SHM 0 offset 0.5 delay 0.2 refid NMEA noselect
+refclock PPS /dev/pps1:clear refid GPS2
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBSHM\fP
+.RS 4
+NTP shared memory driver. This driver uses a shared memory segment to receive
+samples from another process (e.g. \fBgpsd\fP). The parameter is the number of the
+shared memory segment, typically a small number like 0, 1, 2, or 3. The driver
+supports the following option:
+.sp
+\fBperm\fP=\fImode\fP
+.RS 4
+This option specifies the permissions of the shared memory segment created by
+\fBchronyd\fP. They are specified as a numeric mode. The default value is 0600
+(read\-write access for owner only).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock SHM 0 poll 3 refid GPS1
+refclock SHM 1:perm=0644 refid GPS2
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBSOCK\fP
+.RS 4
+Unix domain socket driver. It is similar to the SHM driver, but samples are
+received from a Unix domain socket instead of shared memory and the messages
+have a different format. The parameter is the path to the socket, which
+\fBchronyd\fP creates on start. An advantage over the SHM driver is that SOCK does
+not require polling and it can receive PPS samples with incomplete time. The
+format of the messages is described in the \fIrefclock_sock.c\fP file in the chrony
+source code.
+.sp
+An application which supports the SOCK protocol is the \fBgpsd\fP daemon. The path
+where \fBgpsd\fP expects the socket to be created is described in the \fBgpsd(8)\fP man
+page. For example:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock SOCK /var/run/chrony.ttyS0.sock
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBPHC\fP
+.RS 4
+PTP hardware clock (PHC) driver. The parameter is the path to the device of
+the PTP clock which should be used as a time source. If the clock is kept in
+TAI instead of UTC (e.g. it is synchronised by a PTP daemon), the current
+UTC\-TAI offset needs to be specified by the \fBoffset\fP option. Alternatively, the
+\fBpps\fP refclock option can be enabled to treat the PHC as a PPS refclock, using
+only the sub\-second offset for synchronisation. The driver supports the
+following options:
+.sp
+\fBnocrossts\fP
+.RS 4
+This option disables use of precise cross timestamping.
+.RE
+.sp
+\fBextpps\fP
+.RS 4
+This option enables a PPS mode in which the PTP clock is timestamping pulses
+of an external PPS signal connected to the clock. The clock does not need to be
+synchronised, but another time source is needed to complete the PPS samples.
+Note that some PTP clocks cannot be configured to timestamp only assert or
+clear events, and it is necessary to use the \fBwidth\fP option to filter wrong
+PPS samples.
+.RE
+.sp
+\fBpin\fP=\fIindex\fP
+.RS 4
+This option specifies the index of the pin which should be enabled for the
+PPS timestamping. If the PHC does not have configurable pins (i.e. the channel
+function is fixed), the index needs to be set to \-1 to disable the pin
+configuration. The default value is 0.
+.RE
+.sp
+\fBchannel\fP=\fIindex\fP
+.RS 4
+This option specifies the index of the channel for the PPS mode. The default
+value is 0.
+.RE
+.sp
+\fBclear\fP
+.RS 4
+This option enables timestamping of clear events (falling edge) instead of
+assert events (rising edge) in the PPS mode. This may not work with some
+clocks.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock PHC /dev/ptp0 poll 0 dpoll \-2 offset \-37
+refclock PHC /dev/ptp1:nocrossts poll 3 pps
+refclock PHC /dev/ptp2:extpps:pin=1 width 0.2 poll 2
+.fam
+.fi
+.if n .RE
+.RE
+.RE
+.sp
+
+.RS 4
+The \fBrefclock\fP directive supports the following options:
+.sp
+\fBpoll\fP \fIpoll\fP
+.RS 4
+Timestamps produced by refclock drivers are not used immediately, but they are
+stored and processed by a median filter in the polling interval specified by
+this option. This is defined as a power of 2 and can be negative to specify a
+sub\-second interval. The default is 4 (16 seconds). A shorter interval allows
+\fBchronyd\fP to react faster to changes in the frequency of the system clock, but
+it might have a negative effect on its accuracy if the samples have a lot of
+jitter.
+.RE
+.sp
+\fBdpoll\fP \fIdpoll\fP
+.RS 4
+Some drivers do not listen for external events and try to produce samples in
+their own polling interval. This is defined as a power of 2 and can be negative
+to specify a sub\-second interval. The default is 0 (1 second).
+.RE
+.sp
+\fBrefid\fP \fIrefid\fP
+.RS 4
+This option is used to specify the reference ID of the refclock, as up to four
+ASCII characters. The default reference ID is composed from the first three
+characters of the driver name and the number of the refclock. Each refclock
+must have a unique reference ID.
+.RE
+.sp
+\fBlock\fP \fIrefid\fP
+.RS 4
+This option can be used to lock a PPS refclock to another refclock, which is
+specified by its reference ID. In this mode received PPS samples are paired
+directly with raw samples from the specified refclock.
+.RE
+.sp
+\fBrate\fP \fIrate\fP
+.RS 4
+This option sets the rate of the pulses in the PPS signal (in Hz). This option
+controls how the pulses will be completed with real time. To actually receive
+more than one pulse per second, a negative \fBdpoll\fP has to be specified (\-3 for
+a 5Hz signal). The default is 1.
+.RE
+.sp
+\fBmaxlockage\fP \fIpulses\fP
+.RS 4
+This option specifies in number of pulses how old can be samples from the
+refclock specified by the \fBlock\fP option to be paired with the pulses.
+Increasing this value is useful when the samples are produced at a lower rate
+than the pulses. The default is 2.
+.RE
+.sp
+\fBwidth\fP \fIwidth\fP
+.RS 4
+This option specifies the width of the pulses (in seconds). It is used to
+filter PPS samples when the driver provides samples for both rising and falling
+edges. Note that it reduces the maximum allowed error of the time source which
+completes the PPS samples. If the duty cycle is configurable, 50% should be
+preferred in order to maximise the allowed error.
+.RE
+.sp
+\fBpps\fP
+.RS 4
+This options forces \fBchronyd\fP to treat any refclock (e.g. SHM or PHC) as a PPS
+refclock. This can be useful when the refclock provides time with a variable
+offset of a whole number of seconds (e.g. it uses TAI instead of UTC). Another
+time source is needed to complete samples from the refclock.
+.RE
+.sp
+\fBoffset\fP \fIoffset\fP
+.RS 4
+This option can be used to compensate for a constant error. The specified
+offset (in seconds) is applied to all samples produced by the reference clock.
+The default is 0.0.
+.RE
+.sp
+\fBdelay\fP \fIdelay\fP
+.RS 4
+This option sets the NTP delay of the source (in seconds). Half of this value
+is included in the maximum assumed error which is used in the source selection
+algorithm. Increasing the delay is useful to avoid having no majority in the
+source selection or to make it prefer other sources. The default is 1e\-9 (1
+nanosecond).
+.RE
+.sp
+\fBstratum\fP \fIstratum\fP
+.RS 4
+This option sets the NTP stratum of the refclock. This can be useful when the
+refclock provides time with a stratum other than 0. The default is 0.
+.RE
+.sp
+\fBprecision\fP \fIprecision\fP
+.RS 4
+This option sets the precision of the reference clock (in seconds). The default
+value is the estimated precision of the system clock.
+.RE
+.sp
+\fBmaxdispersion\fP \fIdispersion\fP
+.RS 4
+Maximum allowed dispersion for filtered samples (in seconds). Samples with
+larger estimated dispersion are ignored. By default, this limit is disabled.
+.RE
+.sp
+\fBfilter\fP \fIsamples\fP
+.RS 4
+This option sets the length of the median filter which is used to reduce the
+noise in the measurements. With each poll about 40 percent of the stored
+samples are discarded and one final sample is calculated as an average of the
+remaining samples. If the length is 4 or more, at least 4 samples have to be
+collected between polls. For lengths below 4, the filter has to be full. The
+default is 64.
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+Prefer this source over sources without the prefer option.
+.RE
+.sp
+\fBnoselect\fP
+.RS 4
+Never select this source. This is useful for monitoring or with sources which
+are not very accurate, but are locked with a PPS refclock.
+.RE
+.sp
+\fBtrust\fP
+.RS 4
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+.RE
+.sp
+\fBrequire\fP
+.RS 4
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the \fBtrust\fP option this can be useful to allow a trusted,
+but not very precise, reference clock to be safely combined with
+unauthenticated NTP sources in order to improve the accuracy of the clock. They
+can be selected and used for synchronisation only if they agree with the
+trusted and required source.
+.RE
+.sp
+\fBtai\fP
+.RS 4
+This option indicates that the reference clock keeps time in TAI instead of UTC
+and that \fBchronyd\fP should correct its offset by the current TAI\-UTC offset. The
+\fBleapsectz\fP directive must be used with this option and the
+database must be kept up to date in order for this correction to work as
+expected. This option does not make sense with PPS refclocks.
+.RE
+.sp
+\fBlocal\fP
+.RS 4
+This option specifies that the reference clock is an unsynchronised clock which
+is more stable than the system clock (e.g. TCXO, OCXO, or atomic clock) and
+it should be used as a local standard to stabilise the system clock. The
+refclock will bypass the source selection. There should be at most one refclock
+specified with this option and it should have the shortest polling interval
+among all configured sources.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+Set the minimum number of samples kept for this source. This overrides the
+\fBminsamples\fP directive.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+Set the maximum number of samples kept for this source. This overrides the
+\fBmaxsamples\fP directive.
+.RE
+.RE
+.sp
+\fBmanual\fP
+.RS 4
+The \fBmanual\fP directive enables support at run\-time for the
+\fBsettime\fP command in \fBchronyc\fP. If no \fBmanual\fP
+directive is included, any attempt to use the \fBsettime\fP command in \fBchronyc\fP
+will be met with an error message.
+.sp
+Note that the \fBsettime\fP command can be enabled at run\-time using
+the \fBmanual\fP command in \fBchronyc\fP. (The idea of the two
+commands is that the \fBmanual\fP command controls the manual clock driver\(cqs
+behaviour, whereas the \fBsettime\fP command allows samples of manually entered
+time to be provided.)
+.RE
+.sp
+\fBacquisitionport\fP \fIport\fP
+.RS 4
+By default, \fBchronyd\fP as an NTP client opens a new socket for each request with
+the source port chosen randomly by the operating system. The \fBacquisitionport\fP
+directive can be used to specify the source port and use only one socket (per
+IPv4 or IPv6 address family) for all configured servers. This can be useful for
+getting through some firewalls. It should not be used if not necessary as there
+is a small impact on security of the client. If set to 0, the source port of
+the permanent socket will be chosen randomly by the operating system.
+.sp
+It can be set to the same port as is used by the NTP server (which can be
+configured with the \fBport\fP directive) to use only one socket for all
+NTP packets.
+.sp
+An example of the \fBacquisitionport\fP directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+acquisitionport 1123
+.fam
+.fi
+.if n .RE
+.sp
+This would change the source port used for client requests to UDP port 1123.
+You could then persuade the firewall administrator to open that port.
+.RE
+.sp
+\fBbindacqaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindacqaddress\fP directive specifies a local IP address to which
+\fBchronyd\fP will bind its NTP and NTS\-KE client sockets. The syntax is similar to
+the \fBbindaddress\fP and \fBbindcmdaddress\fP
+directives.
+.sp
+For each of the IPv4 and IPv6 protocols, only one \fBbindacqaddress\fP directive
+can be specified.
+.RE
+.sp
+\fBbindacqdevice\fP \fIinterface\fP
+.RS 4
+The \fBbindacqdevice\fP directive binds the client sockets to a network device
+specified by the interface name. This can be useful when the local address is
+dynamic, or to enable an NTP source specified with a link\-local IPv6 address.
+This directive can specify only one interface and it is supported on Linux
+only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindacqdevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdscp\fP \fIpoint\fP
+.RS 4
+The \fBdscp\fP directive sets the Differentiated Services Code Point (DSCP) in
+transmitted NTP packets to the specified value. It can improve stability of NTP
+measurements in local networks where switches or routers are configured to
+prioritise forwarding of packets with specific DSCP values. The default value
+is 0 and the maximum value is 63.
+.sp
+An example of the directive (setting the Expedited Forwarding class) is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+dscp 46
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdumpdir\fP \fIdirectory\fP
+.RS 4
+To compute the rate of gain or loss of time, \fBchronyd\fP has to store a
+measurement history for each of the time sources it uses.
+.sp
+All supported systems, with the exception of macOS 10.12 and earlier, have
+operating system support for setting the rate of gain or loss to compensate for
+known errors.
+(On macOS 10.12 and earlier, \fBchronyd\fP must simulate such a capability by
+periodically slewing the system clock forwards or backwards by a suitable amount
+to compensate for the error built up since the previous slew.)
+.sp
+For such systems, it is possible to save the measurement history across
+restarts of \fBchronyd\fP (assuming no changes are made to the system clock
+behaviour whilst it is not running). The \fBdumpdir\fP directive defines the
+directory where the measurement histories are saved when \fBchronyd\fP exits,
+or the \fBdump\fP command in \fBchronyc\fP is issued.
+.sp
+If the directory does not exist, it will be created automatically.
+.sp
+The \fB\-r\fP option of \fBchronyd\fP enables loading of the dump files on start. All
+dump files found in the directory will be removed after start, even if the \fB\-r\fP
+option is not present.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+dumpdir @CHRONYRUNDIR@
+.fam
+.fi
+.if n .RE
+.sp
+A source whose IP address is \fI1.2.3.4\fP would have its measurement history saved
+in the file \fI@CHRONYRUNDIR@/1.2.3.4.dat\fP. History of reference clocks is saved
+to files named by their reference ID in form of \fIrefid:XXXXXXXX.dat\fP.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+The \fBmaxsamples\fP directive sets the default maximum number of samples that
+\fBchronyd\fP should keep for each source. This setting can be overridden for
+individual sources in the \fBserver\fP and \fBrefclock\fP
+directives. The default value is 0, which disables the configurable limit. The
+useful range is 4 to 64.
+.sp
+As a special case, setting \fBmaxsamples\fP to 1 disables frequency tracking in
+order to make the sources immediately selectable with only one sample. This can
+be useful when \fBchronyd\fP is started with the \fB\-q\fP or \fB\-Q\fP option.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+The \fBminsamples\fP directive sets the default minimum number of samples that
+\fBchronyd\fP should keep for each source. This setting can be overridden for
+individual sources in the \fBserver\fP and \fBrefclock\fP
+directives. The default value is 6. The useful range is 4 to 64.
+.sp
+Forcing \fBchronyd\fP to keep more samples than it would normally keep reduces
+noise in the estimated frequency and offset, but slows down the response to
+changes in the frequency and offset of the clock. The offsets in the
+\fBtracking\fP and
+\fBsourcestats\fP reports (and the \fItracking.log\fP and
+\fIstatistics.log\fP files) may be smaller than the actual offsets.
+.RE
+.sp
+\fBntsdumpdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies a directory for the client to save NTS cookies it
+received from the server in order to avoid making an NTS\-KE request when
+\fBchronyd\fP is started again. The cookies are saved separately for each NTP
+source in files named by the IP address of the NTS\-KE server (e.g.
+\fI1.2.3.4.nts\fP). By default, the client does not save the cookies.
+.sp
+If the directory does not exist, it will be created automatically.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsdumpdir @CHRONYVARDIR@
+.fam
+.fi
+.if n .RE
+.sp
+This directory is used also by the NTS server to save keys.
+.RE
+.sp
+\fBntsrefresh\fP \fIinterval\fP
+.RS 4
+This directive specifies the maximum interval between NTS\-KE handshakes (in
+seconds) in order to refresh the keys authenticating NTP packets. The default
+value is 2419200 (4 weeks) and the maximum value is 2^31\-1 (68 years).
+.RE
+.sp
+\fBntstrustedcerts\fP [\fIset\-ID\fP] \fIfile\fP|\fIdirectory\fP
+.RS 4
+This directive specifies a file or directory containing certificates (in the
+PEM format) of trusted certificate authorities (CA) which can be used to
+verify certificates of NTS servers.
+.sp
+The optional \fIset\-ID\fP argument is a number in the range 0 through 2^32\-1, which
+selects the set of certificates where certificates from the specified file
+or directory are added. The default ID is 0, which is a set containing the
+system\(cqs default trusted CAs (unless the \fBnosystemcert\fP directive is present).
+All other sets are empty by default. A set of certificates can be selected for
+verification of an NTS server by the \fBcertset\fP option in the \fBserver\fP or \fBpool\fP
+directive.
+.sp
+This directive can be used multiple times to specify one or more sets of
+trusted certificates, each containing certificates from one or more files
+and/or directories.
+.sp
+It is not necessary to restart \fBchronyd\fP in order to reload the certificates if
+they change (e.g. after a renewal).
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntstrustedcerts /etc/pki/nts/foo.crt
+ntstrustedcerts 1 /etc/pki/nts/bar.crt
+ntstrustedcerts 1 /etc/pki/nts/baz.crt
+ntstrustedcerts 2 /etc/pki/nts/qux.crt
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBnosystemcert\fP
+.RS 4
+This directive disables the system\(cqs default trusted CAs. Only certificates
+specified by the \fBntstrustedcerts\fP directive will be trusted.
+.RE
+.sp
+\fBnocerttimecheck\fP \fIlimit\fP
+.RS 4
+This directive disables the checks of the activation and expiration times of
+certificates for the specified number of clock updates. It allows the NTS
+authentication mechanism to be used on computers which start with wrong time
+(e.g. due to not having an RTC or backup battery). Disabling the time checks
+has important security implications and should be used only as a last resort,
+preferably with a minimal number of trusted certificates. The default value is
+0, which means the time checks are always enabled.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+nocerttimecheck 1
+.fam
+.fi
+.if n .RE
+.sp
+This would disable the time checks until the clock is updated for the first
+time, assuming the first update corrects the clock and later checks can work
+with correct time.
+.RE
+.SS "Source selection"
+.sp
+\fBauthselectmode\fP \fImode\fP
+.RS 4
+NTP sources can be specified with the \fBkey\fP or \fBnts\fP option to enable
+authentication to limit the impact of man\-in\-the\-middle attacks. The
+attackers can drop or delay NTP packets (up to the \fBmaxdelay\fP and
+\fBmaxdistance\fP limits), but they cannot modify the timestamps
+contained in the packets. The attack can cause only a limited slew or step, and
+also cause the clock to run faster or slower than real time (up to double of
+the \fBmaxdrift\fP limit).
+.sp
+When authentication is enabled for an NTP source, it is important to disable
+unauthenticated NTP sources which could be exploited in the attack, e.g. if
+they are not reachable only over a trusted network. Alternatively, the source
+selection can be configured with the \fBrequire\fP and \fBtrust\fP options to
+synchronise to the unauthenticated sources only if they agree with the
+authenticated sources and might have a positive impact on the accuracy of the
+clock. Note that in this case the impact of the attack is higher. The attackers
+cannot cause an arbitrarily large step or slew, but they have more control over
+the frequency of the clock and can cause \fBchronyd\fP to report false information,
+e.g. a significantly smaller root delay and dispersion.
+.sp
+This directive determines the default selection options for authenticated and
+unauthenticated sources in order to simplify the configuration with the
+configuration file and \fBchronyc\fP commands. It sets a policy for authentication.
+.sp
+Sources specified with the \fBnoselect\fP option are ignored (not counted as either
+authenticated or unauthenticated), and they always have only the selection
+options specified in the configuration.
+.sp
+There are four modes:
+.sp
+\fBrequire\fP
+.RS 4
+Authentication is strictly required for NTP sources in this mode. If any
+unauthenticated NTP sources are specified, they will automatically get the
+\fBnoselect\fP option to prevent them from being selected for synchronisation.
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+In this mode, authentication is optional and preferred. If it is enabled for at
+least one NTP source, all unauthenticated NTP sources will get the \fBnoselect\fP
+option.
+.RE
+.sp
+\fBmix\fP
+.RS 4
+In this mode, authentication is optional and synchronisation to a mix of
+authenticated and unauthenticated NTP sources is allowed. If both authenticated
+and unauthenticated NTP sources are specified, all authenticated NTP sources
+and reference clocks will get the \fBrequire\fP and \fBtrust\fP options to prevent
+synchronisation to unauthenticated NTP sources if they do not agree with a
+majority of the authenticated sources and reference clocks. This is the default
+mode.
+.RE
+.sp
+\fBignore\fP
+.RS 4
+In this mode, authentication is ignored in the source selection. All sources
+will have only the selection options that were specified in the configuration
+file, or \fBchronyc\fP command. This was the behaviour of \fBchronyd\fP in versions
+before 4.0.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+As an example, the following configuration using the default \fBmix\fP mode:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net nts
+server bar.example.net nts
+server baz.example.net
+refclock SHM 0
+.fam
+.fi
+.if n .RE
+.sp
+is equivalent to the following configuration using the \fBignore\fP mode:
+.sp
+.if n .RS 4
+.nf
+.fam C
+authselectmode ignore
+server foo.example.net nts require trust
+server bar.example.net nts require trust
+server baz.example.net
+refclock SHM 0 require trust
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcombinelimit\fP \fIlimit\fP
+.RS 4
+When \fBchronyd\fP has multiple sources available for synchronisation, it has to
+select one source as the synchronisation source. The measured offsets and
+frequencies of the system clock relative to the other sources, however, can be
+combined with the selected source to improve the accuracy of the system clock.
+.sp
+The \fBcombinelimit\fP directive limits which sources are included in the combining
+algorithm. Their synchronisation distance has to be shorter than the distance
+of the selected source multiplied by the value of the limit. Also, their
+measured frequencies have to be close to the frequency of the selected source.
+If the selected source was specified with the \fBprefer\fP option, it can be
+combined only with other sources specified with this option.
+.sp
+By default, the limit is 3. Setting the limit to 0 effectively disables the
+source combining algorithm and only the selected source will be used to control
+the system clock.
+.RE
+.sp
+\fBmaxdistance\fP \fIdistance\fP
+.RS 4
+The \fBmaxdistance\fP directive sets the maximum root distance of a source to be
+acceptable for synchronisation of the clock. Sources that have a distance
+larger than the specified distance will be rejected. The distance estimates the
+maximum error of the source. It includes the root dispersion and half of the
+root delay (round\-trip time) accumulated on the path to the primary source.
+.sp
+By default, the maximum root distance is 3 seconds.
+.sp
+Setting \fBmaxdistance\fP to a larger value can be useful to allow synchronisation
+with a server that only has a very infrequent connection to its sources and can
+accumulate a large dispersion between updates of its clock.
+.RE
+.sp
+\fBmaxjitter\fP \fIjitter\fP
+.RS 4
+The \fBmaxjitter\fP directive sets the maximum allowed jitter of the sources to not
+be rejected by the source selection algorithm. This prevents synchronisation
+with sources that have a small root distance, but their time is too variable.
+.sp
+By default, the maximum jitter is 1 second.
+.RE
+.sp
+\fBminsources\fP \fIsources\fP
+.RS 4
+The \fBminsources\fP directive sets the minimum number of sources that need to be
+considered as selectable in the source selection algorithm before the local
+clock is updated. The default value is 1.
+.sp
+Setting this option to a larger number can be used to improve the reliability.
+More sources will have to agree with each other and the clock will not be
+updated when only one source (which could be serving incorrect time) is
+reachable.
+.RE
+.sp
+\fBreselectdist\fP \fIdistance\fP
+.RS 4
+When \fBchronyd\fP selects a synchronisation source from available sources, it
+will prefer the one with the shortest synchronisation distance. However, to
+avoid frequent reselecting when there are sources with similar distance, a
+fixed distance is added to the distance for sources that are currently not
+selected. This can be set with the \fBreselectdist\fP directive. By default, the
+distance is 100 microseconds.
+.RE
+.sp
+\fBstratumweight\fP \fIdistance\fP
+.RS 4
+The \fBstratumweight\fP directive sets how much distance should be added per
+stratum to the synchronisation distance when \fBchronyd\fP selects the
+synchronisation source from available sources.
+.sp
+By default, the weight is 0.001 seconds. This means that the stratum of the sources
+in the selection process matters only when the differences between the
+distances are in milliseconds.
+.RE
+.SS "System clock"
+.sp
+\fBclockprecision\fP \fIprecision\fP
+.RS 4
+The \fBclockprecision\fP directive specifies the precision of the system clock (in
+seconds). It is used by \fBchronyd\fP to estimate the minimum noise in NTP
+measurements and randomise low\-order bits of timestamps in NTP responses. By
+default, the precision is measured on start as the minimum time to read the
+clock.
+.sp
+The measured value works well in most cases. However, it generally
+overestimates the precision and it can be sensitive to the CPU speed, which can
+change over time to save power. In some cases with a high\-precision clocksource
+(e.g. the Time Stamp Counter of the CPU) and hardware timestamping, setting the
+precision on the server to a smaller value can improve stability of clients\(aq
+NTP measurements. The server\(cqs precision is reported on clients by the
+\fBntpdata\fP command.
+.sp
+An example setting the precision to 8 nanoseconds is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clockprecision 8e\-9
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcorrtimeratio\fP \fIratio\fP
+.RS 4
+When \fBchronyd\fP is slewing the system clock to correct an offset, the rate at
+which it is slewing adds to the frequency error of the clock. On all supported
+systems, with the exception of macOS 12 and earlier, this rate can be
+controlled.
+.sp
+The \fBcorrtimeratio\fP directive sets the ratio between the duration in which the
+clock is slewed for an average correction according to the source history and
+the interval in which the corrections are done (usually the NTP polling
+interval). Corrections larger than the average take less time and smaller
+corrections take more time, the amount of the correction and the correction
+time are inversely proportional.
+.sp
+Increasing \fBcorrtimeratio\fP improves the overall frequency error of the system
+clock, but increases the overall time error as the corrections take longer.
+.sp
+By default, the ratio is set to 3, the time accuracy of the clock is preferred
+over its frequency accuracy.
+.sp
+The maximum allowed slew rate can be set by the \fBmaxslewrate\fP
+directive. The current remaining correction is shown in the
+\fBtracking\fP report as the \fBSystem time\fP value.
+.RE
+.sp
+\fBdriftfile\fP \fIfile\fP
+.RS 4
+One of the main activities of the \fBchronyd\fP program is to work out the rate at
+which the system clock gains or loses time relative to real time.
+.sp
+Whenever \fBchronyd\fP computes a new value of the gain or loss rate, it is desirable
+to record it somewhere. This allows \fBchronyd\fP to begin compensating the system
+clock at that rate whenever it is restarted, even before it has had a chance to
+obtain an equally good estimate of the rate during the new run. (This process
+can take many minutes, at least.)
+.sp
+The \fBdriftfile\fP directive allows a file to be specified into which \fBchronyd\fP
+can store the rate information. Two parameters are recorded in the file. The
+first is the rate at which the system clock gains or loses time, expressed in
+parts per million, with gains positive. Therefore, a value of 100.0 indicates
+that when the system clock has advanced by a second, it has gained 100
+microseconds in reality (so the true time has only advanced by 999900
+microseconds). The second is an estimate of the error bound around the first
+value in which the true rate actually lies.
+.sp
+An example of the driftfile directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+driftfile @CHRONYVARDIR@/drift
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBfallbackdrift\fP \fImin\-interval\fP \fImax\-interval\fP
+.RS 4
+Fallback drifts are long\-term averages of the system clock drift calculated
+over exponentially increasing intervals. They are used to avoid quickly
+drifting away from true time when the clock was not updated for a longer period
+of time and there was a short\-term deviation in the drift before the updates
+stopped.
+.sp
+The directive specifies the minimum and maximum interval since the last clock
+update to switch between fallback drifts. They are defined as a power of 2 (in
+seconds). The syntax is as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+fallbackdrift 16 19
+.fam
+.fi
+.if n .RE
+.sp
+In this example, the minimum interval is 16 (18 hours) and the maximum interval is
+19 (6 days). The system clock frequency will be set to the first fallback 18
+hours after last clock update, to the second after 36 hours, and so on. This
+might be a good setting to cover frequency changes due to daily and weekly
+temperature fluctuations. When the frequency is set to a fallback, the state of
+the clock will change to \(oqNot synchronised\(cq.
+.sp
+By default (or if the specified maximum or minimum is 0), no fallbacks are used
+and the clock frequency changes only with new measurements from NTP sources,
+reference clocks, or manual input.
+.RE
+.sp
+\fBleapsecmode\fP \fImode\fP
+.RS 4
+A leap second is an adjustment that is occasionally applied to UTC to keep it
+close to the mean solar time. When a leap second is inserted, the last day of
+June or December has an extra second 23:59:60.
+.sp
+For computer clocks that is a problem. The Unix time is defined as number of
+seconds since 00:00:00 UTC on 1 January 1970 without leap seconds. The system
+clock cannot have time 23:59:60, every minute has 60 seconds and every day has
+86400 seconds by definition. The inserted leap second is skipped and the clock
+is suddenly ahead of UTC by one second. The \fBleapsecmode\fP directive selects how
+that error is corrected. There are four options:
+.sp
+\fBsystem\fP
+.RS 4
+When inserting a leap second, the kernel steps the system clock backwards by
+one second when the clock gets to 00:00:00 UTC. When deleting a leap second, it
+steps forward by one second when the clock gets to 23:59:59 UTC. This is the
+default mode when the system driver supports leap seconds (i.e. all supported
+systems with the exception of macOS 12 and earlier).
+.RE
+.sp
+\fBstep\fP
+.RS 4
+This is similar to the \fBsystem\fP mode, except the clock is stepped by
+\fBchronyd\fP instead of the kernel. It can be useful to avoid bugs in the kernel
+code that would be executed in the \fBsystem\fP mode. This is the default mode
+when the system driver does not support leap seconds.
+.RE
+.sp
+\fBslew\fP
+.RS 4
+The clock is corrected by slewing started at 00:00:00 UTC when a leap second
+is inserted or 23:59:59 UTC when a leap second is deleted. This might be
+preferred over the \fBsystem\fP and \fBstep\fP modes when applications running on the
+system are sensitive to jumps in the system time and it is acceptable that the
+clock will be off for a longer time. On Linux with the default
+\fBmaxslewrate\fP value the correction takes 12 seconds.
+.RE
+.sp
+\fBignore\fP
+.RS 4
+No correction is applied to the clock for the leap second. The clock will be
+corrected later in normal operation when new measurements are made and the
+estimated offset includes the one second error. This option is particularly
+useful when multiple \fBchronyd\fP instances are running on the system, one
+controlling the system clock and others started with the \fB\-x\fP option, which
+should rely on the first instance to correct the system clock and ignore it for
+the correction of their own NTP clock running on top of the system clock.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+When serving time to NTP clients that cannot be configured to correct their
+clocks for a leap second by slewing, or to clients that would correct at
+slightly different rates when it is necessary to keep them close together, the
+\fBslew\fP mode can be combined with the \fBsmoothtime\fP directive to
+enable a server leap smear.
+.sp
+When smearing a leap second, the leap status is suppressed on the server and
+the served time is corrected slowly by slewing instead of stepping. The clients
+do not need any special configuration as they do not know there is any leap
+second and they follow the server time which eventually brings them back to
+UTC. Care must be taken to ensure they use only NTP servers which smear the
+leap second in exactly the same way for synchronisation.
+.sp
+This feature must be used carefully, because the server is intentionally not
+serving its best estimate of the true time.
+.sp
+A recommended configuration to enable a server leap smear is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+leapsecmode slew
+maxslewrate 1000
+smoothtime 400 0.001024 leaponly
+.fam
+.fi
+.if n .RE
+.sp
+The first directive is necessary to disable the clock step which would reset
+the smoothing process. The second directive limits the slewing rate of the
+local clock to 1000 ppm, which improves the stability of the smoothing process
+when the local correction starts and ends. The third directive enables the
+server time smoothing process. It will start when the clock gets to 00:00:00
+UTC and it will take 62500 seconds (about 17.36 hours) to finish. The frequency
+offset will be changing by 0.001024 ppm per second and will reach a maximum of
+32 ppm in 31250 seconds. The \fBleaponly\fP option makes the duration of the leap
+smear constant and allows the clients to safely synchronise with multiple
+identically configured leap smearing servers.
+.sp
+The duration of the leap smear can be calculated from the specified wander as
+.sp
+.if n .RS 4
+.nf
+.fam C
+duration = sqrt(4 / wander)
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBleapsectz\fP \fItimezone\fP
+.RS 4
+This directive specifies a timezone in the system timezone database which
+\fBchronyd\fP can use to determine when will the next leap second occur and what is
+the current offset between TAI and UTC. It will periodically check if 23:59:59
+and 23:59:60 are valid times in the timezone. This normally works with the
+\fIright/UTC\fP timezone.
+.sp
+When a leap second is announced, the timezone needs to be updated at least 12
+hours before the leap second. It is not necessary to restart \fBchronyd\fP.
+.sp
+This directive is useful with reference clocks and other time sources which do
+not announce leap seconds, or announce them too late for an NTP server to
+forward them to its own clients. Clients of leap smearing servers must not
+use this directive.
+.sp
+It is also useful when the system clock is required to have correct TAI\-UTC
+offset. Note that the offset is set only when leap seconds are handled by the
+kernel, i.e. \fBleapsecmode\fP is set to \fBsystem\fP.
+.sp
+The specified timezone is not used as an exclusive source of information about
+leap seconds. If a majority of time sources announce on the last day of June or
+December that a leap second should be inserted or deleted, it will be accepted
+even if it is not included in the timezone.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+leapsectz right/UTC
+.fam
+.fi
+.if n .RE
+.sp
+The following shell command verifies that the timezone contains leap seconds
+and can be used with this directive:
+.sp
+.if n .RS 4
+.nf
+.fam C
+$ TZ=right/UTC date \-d \(aqDec 31 2008 23:59:60\(aq
+Wed Dec 31 23:59:60 UTC 2008
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmakestep\fP \fIthreshold\fP \fIlimit\fP
+.RS 4
+Normally \fBchronyd\fP will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+e.g. when \fBchronyd\fP is initially started, the system clock might be so far
+adrift that this slewing process would take a very long time to correct the
+system clock.
+.sp
+This directive forces \fBchronyd\fP to step the system clock if the adjustment is
+larger than a threshold value, but only if there were no more clock updates
+since \fBchronyd\fP was started than the specified limit. A negative value disables
+the limit.
+.sp
+On most systems it is desirable to step the system clock only on boot, before
+starting programs that rely on time advancing monotonically forwards.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+makestep 0.1 3
+.fam
+.fi
+.if n .RE
+.sp
+This would step the system clock if the adjustment is larger than 0.1 seconds, but
+only in the first three clock updates.
+.RE
+.sp
+\fBmaxchange\fP \fIoffset\fP \fIstart\fP \fIignore\fP
+.RS 4
+This directive sets the maximum offset to be accepted on a clock update. The
+offset is measured relative to the current estimate of the true time, which is
+different from the system time if a previous slew did not finish.
+.sp
+The check is enabled after the specified number of clock updates to allow a
+large initial offset to be corrected on start. Offsets larger than the
+specified maximum will be ignored for the specified number of times. Another
+large offset will cause \fBchronyd\fP to give up and exit. A negative value
+can be used to disable the limit to ignore all large offsets. A syslog message
+will be generated when an offset is ignored or it causes the exit.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+maxchange 1000 1 2
+.fam
+.fi
+.if n .RE
+.sp
+After the first clock update, \fBchronyd\fP will check the offset on every clock
+update, it will ignore two adjustments larger than 1000 seconds and exit on
+another one.
+.RE
+.sp
+\fBmaxclockerror\fP \fIerror\-in\-ppm\fP
+.RS 4
+The \fBmaxclockerror\fP directive sets the maximum assumed frequency error that the
+system clock can gain on its own between clock updates. It describes the
+stability of the clock.
+.sp
+By default, the maximum error is 1 ppm.
+.sp
+Typical values for \fIerror\-in\-ppm\fP might be 10 for a low quality clock and 0.1
+for a high quality clock using a temperature compensated crystal oscillator.
+.RE
+.sp
+\fBmaxdrift\fP \fIdrift\-in\-ppm\fP
+.RS 4
+This directive specifies the maximum assumed drift (frequency error) of the
+system clock. It limits the frequency adjustment that \fBchronyd\fP is allowed to
+use to correct the measured drift. It is an additional limit to the maximum
+adjustment that can be set by the system driver (100000 ppm on Linux, 500 ppm
+on FreeBSD, NetBSD, and macOS 10.13+, 32500 ppm on illumos).
+.sp
+By default, the maximum assumed drift is 500000 ppm, i.e. the adjustment is
+limited by the system driver rather than this directive.
+.RE
+.sp
+\fBmaxupdateskew\fP \fIskew\-in\-ppm\fP
+.RS 4
+One of \fBchronyd\fP\(aqs tasks is to work out how fast or slow the computer\(cqs clock
+runs relative to its reference sources. In addition, it computes an estimate of
+the error bounds around the estimated value.
+.sp
+If the range of error is too large, it probably indicates that the measurements
+have not settled down yet, and that the estimated gain or loss rate is not very
+reliable.
+.sp
+The \fBmaxupdateskew\fP directive sets the threshold for determining whether an
+estimate might be so unreliable that it should not be used. By default, the
+threshold is 1000 ppm.
+.sp
+Typical values for \fIskew\-in\-ppm\fP might be 100 for NTP sources polled over a
+wireless network, and 10 or smaller for sources on a local wired network.
+.sp
+It should be noted that this is not the only means of protection against using
+unreliable estimates. At all times, \fBchronyd\fP keeps track of both the estimated
+gain or loss rate, and the error bound on the estimate. When a new estimate is
+generated following another measurement from one of the sources, a weighted
+combination algorithm is used to update the master estimate. So if \fBchronyd\fP
+has an existing highly\-reliable master estimate and a new estimate is generated
+which has large error bounds, the existing master estimate will dominate in the
+new master estimate.
+.RE
+.sp
+\fBmaxslewrate\fP \fIrate\-in\-ppm\fP
+.RS 4
+The \fBmaxslewrate\fP directive sets the maximum rate at which \fBchronyd\fP is allowed
+to slew the time. It limits the slew rate controlled by the correction time
+ratio (which can be set by the \fBcorrtimeratio\fP directive) and
+is effective only on systems where \fBchronyd\fP is able to control the rate (i.e.
+all supported systems with the exception of macOS 12 or earlier).
+.sp
+For each system there is a maximum frequency offset of the clock that can be set
+by the driver. On Linux it is 100000 ppm, on FreeBSD, NetBSD and macOS 10.13+ it
+is 5000 ppm, and on illumos it is 32500 ppm. Also, due to a kernel limitation,
+setting \fBmaxslewrate\fP on FreeBSD, NetBSD, macOS 10.13+ to a value between 500
+ppm and 5000 ppm will effectively set it to 500 ppm.
+.sp
+By default, the maximum slew rate is set to 83333.333 ppm (one twelfth).
+.RE
+.sp
+\fBtempcomp\fP \fIfile\fP \fIinterval\fP \fIT0\fP \fIk0\fP \fIk1\fP \fIk2\fP, \fBtempcomp\fP \fIfile\fP \fIinterval\fP \fIpoints\-file\fP
+.RS 4
+Normally, changes in the rate of drift of the system clock are caused mainly by
+changes in the temperature of the crystal oscillator on the motherboard.
+.sp
+If there are temperature measurements available from a sensor close to the
+oscillator, the \fBtempcomp\fP directive can be used to compensate for the changes
+in the temperature and improve the stability and accuracy of the clock.
+.sp
+The result depends on many factors, including the resolution of the sensor, the
+amount of noise in the measurements, the polling interval of the time source,
+the compensation update interval, how well the compensation is specified, and
+how close the sensor is to the oscillator. When it is working well, the
+frequency reported in the \fItracking.log\fP file is more stable and the maximum
+reached offset is smaller.
+.sp
+There are two forms of the directive. The first one has six parameters: a path
+to the file containing the current temperature from the sensor (in text
+format), the compensation update interval (in seconds), and temperature
+coefficients \fIT0\fP, \fIk0\fP, \fIk1\fP, \fIk2\fP.
+.sp
+The frequency compensation is calculated (in ppm) as
+.sp
+.if n .RS 4
+.nf
+.fam C
+comp = k0 + (T \- T0) * k1 + (T \- T0)^2 * k2
+.fam
+.fi
+.if n .RE
+.sp
+The result has to be between \-10 ppm and 10 ppm, otherwise the measurement is
+considered invalid and will be ignored. The \fIk0\fP coefficient can be adjusted to
+keep the compensation in that range.
+.sp
+An example of the use is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 26000 0.0 0.000183 0.0
+.fam
+.fi
+.if n .RE
+.sp
+The measured temperature will be read from the file in the Linux sysfs
+filesystem every 30 seconds. When the temperature is 26000 (26 degrees
+Celsius), the frequency correction will be zero. When it is 27000 (27 degrees
+Celsius), the clock will be set to run faster by 0.183 ppm, etc.
+.sp
+The second form has three parameters: the path to the sensor file, the update
+interval, and a path to a file containing a list of (temperature, compensation)
+points, from which the compensation is linearly interpolated or extrapolated.
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 /etc/chrony.tempcomp
+.fam
+.fi
+.if n .RE
+.sp
+where the \fI/etc/chrony.tempcomp\fP file could have
+.sp
+.if n .RS 4
+.nf
+.fam C
+20000 1.0
+21000 0.64
+22000 0.36
+23000 0.16
+24000 0.04
+25000 0.0
+26000 0.04
+27000 0.16
+28000 0.36
+29000 0.64
+30000 1.0
+.fam
+.fi
+.if n .RE
+.sp
+Valid measurements with corresponding compensations are logged to the
+\fItempcomp.log\fP file if enabled by the \fBlog tempcomp\fP directive.
+.RE
+.SS "NTP server"
+.sp
+\fBallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The \fBallow\fP directive is used to designate a particular subnet from which NTP
+clients are allowed to access the computer as an NTP server. It also controls
+access of NTS\-KE clients when NTS is enabled on the server.
+.sp
+The default is that no clients are allowed access, i.e. \fBchronyd\fP operates
+purely as an NTP client. If the \fBallow\fP directive is used, \fBchronyd\fP will be
+both a client of its servers, and a server to other clients.
+.sp
+This directive can be used multiple times.
+.sp
+Examples of the use of the directive are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+allow 3.4.5.0/24
+allow 3.4.5
+allow 2001:db8::/32
+allow 0/0
+allow ::/0
+allow
+.fam
+.fi
+.if n .RE
+.sp
+The first directive allows access from an IPv4 address. The second directive
+allows access from all computers in an IPv4 subnet specified in the CIDR
+notation. The third directive specifies the same subnet using a simpler
+notation where the prefix length is determined by the number of dots. The
+fourth directive specifies an IPv6 subnet. The fifth and sixth directives allow
+access from all IPv4 and IPv6 addresses respectively. The seventh directive
+allows access from all addresses (both IPv4 or IPv6).
+.sp
+A second form of the directive, \fBallow all\fP, has a greater effect, depending on
+the ordering of directives in the configuration file. To illustrate the effect,
+consider the two examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow 1.2.0.0/16
+.fam
+.fi
+.if n .RE
+.sp
+and
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow all 1.2.0.0/16
+.fam
+.fi
+.if n .RE
+.sp
+In the first example, the effect is the same regardless of what order the three
+directives are given in. So the \fI1.2.0.0/16\fP subnet is allowed access, except
+for the \fI1.2.3.0/24\fP subnet, which is denied access, however the host \fI1.2.3.4\fP
+is allowed access.
+.sp
+In the second example, the \fBallow all 1.2.0.0/16\fP directive overrides the
+effect of \fIany\fP previous directive relating to a subnet within the specified
+subnet. Within a configuration file this capability is probably rather moot;
+however, it is of greater use for reconfiguration at run\-time via \fBchronyc\fP
+with the \fBallow all\fP command.
+.sp
+The rules are internally represented as a tree of tables with one level per
+four bits of the IPv4 or IPv6 address. The order of the \fBallow\fP and \fBdeny\fP
+directives matters if they modify the same records of one table, i.e. if one
+subnet is included in the other subnet and their prefix lengths are at the same
+level. For example, \fI1.2.3.0/28\fP and \fI1.2.3.0/29\fP are in different tables, but
+\fI1.2.3.0/25\fP and \fI1.2.3.0/28\fP are in the same table. The configuration can be
+verified for individual addresses with the \fBaccheck\fP
+command in \fBchronyc\fP.
+.sp
+A hostname can be specified in the directives instead of the IP address, but
+the name must be resolvable when \fBchronyd\fP is started, i.e. the network is
+already up and DNS is working. If the hostname resolves to multiple addresses,
+only the first address (in the order returned by the system resolver) will be
+allowed or denied.
+.sp
+Note, if the \fBinitstepslew\fP directive is used in the
+configuration file, each of the computers listed in that directive must allow
+client access by this computer for it to work.
+.RE
+.sp
+\fBdeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP directive, except that it denies NTP
+and NTS\-KE client access to a particular subnet or host, rather than allowing
+it.
+.sp
+The syntax is identical and the directive can be used multiple times too.
+.sp
+There is also a \fBdeny all\fP directive with similar behaviour to the \fBallow all\fP
+directive.
+.RE
+.sp
+\fBbindaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindaddress\fP directive binds the sockets on which \fBchronyd\fP listens for
+NTP and NTS\-KE requests to a local address of the computer. On systems other
+than Linux, the address of the computer needs to be already configured when
+\fBchronyd\fP is started.
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindaddress 192.168.1.1
+.fam
+.fi
+.if n .RE
+.sp
+Currently, for each of the IPv4 and IPv6 protocols, only one \fBbindaddress\fP
+directive can be specified. Therefore, it is not useful on computers which
+should serve NTP on multiple network interfaces.
+.RE
+.sp
+\fBbinddevice\fP \fIinterface\fP
+.RS 4
+The \fBbinddevice\fP directive binds the NTP and NTS\-KE server sockets to a network
+device specified by the interface name. This directive can specify only one
+interface and it is supported on Linux only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+binddevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBbroadcast\fP \fIinterval\fP \fIaddress\fP [\fIport\fP]
+.RS 4
+The \fBbroadcast\fP directive is used to declare a broadcast address to which
+chronyd should send packets in the NTP broadcast mode (i.e. make \fBchronyd\fP act
+as a broadcast server). Broadcast clients on that subnet will be able to
+synchronise.
+.sp
+This directive can be used multiple times to specify multiple addresses.
+.sp
+The syntax is as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+broadcast 32 192.168.1.255
+broadcast 64 192.168.2.255 12123
+broadcast 64 ff02::101
+.fam
+.fi
+.if n .RE
+.sp
+In the first example, the destination port defaults to UDP port 123 (the normal NTP
+port). In the second example, the destination port is specified as 12123. The
+first parameter in each case (32 or 64 respectively) is the interval in seconds
+between broadcast packets being sent. The second parameter in each case is the
+broadcast address to send the packet to. This should correspond to the
+broadcast address of one of the network interfaces on the computer where
+\fBchronyd\fP is running.
+.sp
+You can have more than 1 \fBbroadcast\fP directive if you have more than 1 network
+interface onto which you want to send NTP broadcast packets.
+.sp
+\fBchronyd\fP itself cannot act as a broadcast client; it must always be configured
+as a point\-to\-point client by defining specific NTP servers and peers. This
+broadcast server feature is intended for providing a time source to other NTP
+implementations.
+.sp
+If \fBntpd\fP is used as the broadcast client, it will try to measure the
+round\-trip delay between the server and client with normal client mode packets.
+Thus, the broadcast subnet should also be the subject of an \fBallow\fP
+directive.
+.RE
+.sp
+\fBclientloglimit\fP \fIlimit\fP
+.RS 4
+This directive specifies the maximum amount of memory that \fBchronyd\fP is allowed
+to allocate for logging of client accesses and the state that \fBchronyd\fP as an
+NTP server needs to support the interleaved mode for its clients. The default
+limit is 524288 bytes, which enables monitoring of up to 4096 IP addresses at
+the same time and holding NTP timestamps for up to 4096 clients using the
+interleaved mode (depending on uniformity of their polling interval). The
+number of addresses and timestamps is always a power of 2. The maximum
+effective value is 2147483648 (2 GB), which corresponds to 16777216 addresses
+and timestamps.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clientloglimit 1048576
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBnoclientlog\fP
+.RS 4
+This directive, which takes no arguments, specifies that client accesses are
+not to be logged. Normally they are logged, allowing statistics to be reported
+using the \fBclients\fP command in \fBchronyc\fP. This option
+also effectively disables server support for the NTP interleaved mode.
+.RE
+.sp
+\fBlocal\fP [\fIoption\fP]...
+.RS 4
+The \fBlocal\fP directive enables a local reference mode, which allows \fBchronyd\fP
+operating as an NTP server to appear synchronised to real time (from the
+viewpoint of clients polling it), even when it was never synchronised or
+the last update of the clock happened a long time ago.
+.sp
+This directive is normally used in an isolated network, where computers are
+required to be synchronised to one another, but not necessarily to real time.
+The server can be kept vaguely in line with real time by manual input.
+.sp
+The \fBlocal\fP directive has the following options:
+.sp
+\fBstratum\fP \fIstratum\fP
+.RS 4
+This option sets the stratum of the server which will be reported to clients
+when the local reference is active. The specified value is in the range 1
+through 15, and the default value is 10. It should be larger than the maximum
+expected stratum in the network when external NTP servers are accessible.
+.sp
+Stratum 1 indicates a computer that has a true real\-time reference directly
+connected to it (e.g. GPS, atomic clock, etc.), such computers are expected to
+be very close to real time. Stratum 2 computers are those which have a stratum
+1 server; stratum 3 computers have a stratum 2 server and so on. A value
+of 10 indicates that the clock is so many hops away from a reference clock that
+its time is fairly unreliable.
+.RE
+.sp
+\fBdistance\fP \fIdistance\fP
+.RS 4
+This option sets the threshold for the root distance which will activate the local
+reference. If \fBchronyd\fP was synchronised to some source, the local reference
+will not be activated until its root distance reaches the specified value (the
+rate at which the distance is increasing depends on how well the clock was
+tracking the source). The default value is 1 second.
+.sp
+The current root distance can be calculated from root delay and root dispersion
+(reported by the \fBtracking\fP command in \fBchronyc\fP) as:
+.sp
+.if n .RS 4
+.nf
+.fam C
+distance = delay / 2 + dispersion
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBorphan\fP
+.RS 4
+This option enables a special \(oqorphan\(cq mode, where sources with stratum equal
+to the local \fIstratum\fP are assumed to not serve real time. They are ignored
+unless no other source is selectable and their reference IDs are smaller than
+the local reference ID.
+.sp
+This allows multiple servers in the network to use the same \fBlocal\fP
+configuration and to be synchronised to one another, without confusing clients
+that poll more than one server. Each server needs to be configured to poll all
+other servers with the \fBlocal\fP directive. This ensures only the server with the
+smallest reference ID has the local reference active and others are
+synchronised to it. If that server stops responding, the server with the second
+smallest reference ID will take over when its local reference mode activates
+(root distance reaches the threshold configured by the \fBdistance\fP option).
+.sp
+The \fBorphan\fP mode is compatible with the \fBntpd\fP\(aqs orphan mode (enabled by the
+\fBtos orphan\fP command).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+local stratum 10 orphan distance 0.1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBntpsigndsocket\fP \fIdirectory\fP
+.RS 4
+This directive specifies the location of the Samba \fBntp_signd\fP socket when it
+is running as a Domain Controller (DC). If \fBchronyd\fP is compiled with this
+feature, responses to MS\-SNTP clients will be signed by the \fBsmbd\fP daemon.
+.sp
+Note that MS\-SNTP requests are not authenticated and any client that is allowed
+to access the server by the \fBallow\fP directive, or the
+\fBallow\fP command in \fBchronyc\fP, can get an MS\-SNTP
+response signed with a trust account\(cqs password and try to crack the password
+in a brute\-force attack. Access to the server should be carefully controlled.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntpsigndsocket /var/lib/samba/ntp_signd
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBntsport\fP \fIport\fP
+.RS 4
+This directive specifies the TCP port on which \fBchronyd\fP will provide the NTS
+Key Establishment (NTS\-KE) service. The default port is 4460.
+.sp
+The port will be open only when a certificate and key is specified by the
+\fBntsservercert\fP and \fBntsserverkey\fP directives.
+.RE
+.sp
+\fBntsservercert\fP \fIfile\fP
+.RS 4
+This directive specifies a file containing a certificate in the PEM format
+for \fBchronyd\fP to operate as an NTS server. The file should also include
+any intermediate certificates that the clients will need to validate the
+server\(cqs certificate. The file needs to be readable by the user under which
+\fBchronyd\fP is running after dropping root privileges.
+.sp
+This directive can be used multiple times to specify multiple certificates for
+different names of the server.
+.sp
+The files are loaded only once. \fBchronyd\fP needs to be restarted in order to
+load a renewed certificate. The \fBntsdumpdir\fP and
+\fBdumpdir\fP directives with the \fB\-r\fP option of \fBchronyd\fP are
+recommended for a near\-seamless server operation.
+.RE
+.sp
+\fBntsserverkey\fP \fIfile\fP
+.RS 4
+This directive specifies a file containing a private key in the PEM format
+for \fBchronyd\fP to operate as an NTS server. The file needs to be readable by
+the user under which \fBchronyd\fP is running after dropping root privileges. For
+security reasons, it should not be readable by other users.
+.sp
+This directive can be used multiple times to specify multiple keys. The number
+of keys must be the same as the number of certificates and the corresponding
+files must be specified in the same order.
+.RE
+.sp
+\fBntsprocesses\fP \fIprocesses\fP
+.RS 4
+This directive specifies how many helper processes will \fBchronyd\fP operating
+as an NTS server start for handling client NTS\-KE requests in order to improve
+performance with multi\-core CPUs and multithreading. If set to 0, no helper
+process will be started and all NTS\-KE requests will be handled by the main
+\fBchronyd\fP process. The default value is 1.
+.RE
+.sp
+\fBmaxntsconnections\fP \fIconnections\fP
+.RS 4
+This directive specifies the maximum number of concurrent NTS\-KE connections
+per process that the NTS server will accept. The default value is 100. The
+maximum practical value is half of the system \fBFD_SETSIZE\fP constant (usually
+1024).
+.RE
+.sp
+\fBntsdumpdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies a directory where \fBchronyd\fP operating as an NTS server
+can save the keys which encrypt NTS cookies provided to clients. The keys are
+saved to a single file named \fIntskeys\fP. When \fBchronyd\fP is restarted, reloading
+the keys allows the clients to continue using old cookies and avoids a storm of
+NTS\-KE requests. By default, the server does not save the keys.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsdumpdir @CHRONYVARDIR@
+.fam
+.fi
+.if n .RE
+.sp
+This directory is used also by the NTS client to save NTS cookies.
+.RE
+.sp
+\fBntsntpserver\fP \fIhostname\fP
+.RS 4
+This directive specifies the hostname (as a fully qualified domain name) or
+address of the NTP server(s) which is
+provided in the NTS\-KE response to the clients. It allows the NTS\-KE server to
+be separated from the NTP server. However, the servers need to share the keys,
+i.e. external key management needs to be enabled by setting
+\fBntsrotate\fP to 0. By default, no hostname or address is provided
+to the clients, which means they should use the same server for NTS\-KE and NTP.
+.RE
+.sp
+\fBntsrotate\fP \fIinterval\fP
+.RS 4
+This directive specifies the rotation interval (in seconds) of the server key
+which encrypts the NTS cookies. New keys are generated automatically from the
+\fI/dev/urandom\fP device. The server keeps two previous keys to give the clients
+time to get new cookies encrypted by the latest key. The interval is measured
+as the server\(cqs operating time, i.e. the actual interval can be longer if
+\fBchronyd\fP is not running continuously. The default interval is 604800 seconds
+(1 week). The maximum value is 2^31\-1 (68 years).
+.sp
+The automatic rotation of the keys can be disabled by setting \fBntsrotate\fP to 0.
+In this case the keys are assumed to be managed externally. \fBchronyd\fP will not
+save the keys to the \fIntskeys\fP file and will reload the keys from the file when
+the \fBrekey\fP command is issued in \fBchronyc\fP. The file can
+be periodically copied from another server running \fBchronyd\fP (which does
+not have \fBntsrotate\fP set to 0) in order to have one or more servers dedicated
+to NTS\-KE. The NTS\-KE servers need to be configured with the
+\fBntsntpserver\fP directive to point the clients to the right NTP
+server.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsrotate 2592000
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBport\fP \fIport\fP
+.RS 4
+This option allows you to configure the port on which \fBchronyd\fP will listen for
+NTP requests. The port will be open only when an address is allowed by the
+\fBallow\fP directive or the \fBallow\fP command in
+\fBchronyc\fP, an NTP peer is configured, or the broadcast server mode is enabled.
+.sp
+The default value is 123, the standard NTP port. If set to 0, \fBchronyd\fP will
+never open the server port and will operate strictly in a client\-only mode. The
+source port used in NTP client requests can be set by the
+\fBacquisitionport\fP directive.
+.RE
+.sp
+\fBratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables response rate limiting for NTP packets. Its purpose is
+to reduce network traffic with misconfigured or broken NTP clients that are
+polling the server too frequently. The limits are applied to individual IP
+addresses. If multiple clients share one IP address (e.g. multiple hosts behind
+NAT), the sum of their traffic will be limited. If a client that increases its
+polling rate when it does not receive a reply is detected, its rate limiting
+will be temporarily suspended to avoid increasing the overall amount of
+traffic. The maximum number of IP addresses which can be monitored at the same
+time depends on the memory limit set by the \fBclientloglimit\fP
+directive.
+.sp
+The \fBratelimit\fP directive supports a number of options (which can be defined
+in any order):
+.sp
+\fBinterval\fP \fIinterval\fP
+.RS 4
+This option sets the minimum interval between responses. It is defined as a
+power of 2 in seconds. The default value is 3 (8 seconds). The minimum value
+is \-19 (524288 packets per second) and the maximum value is 12 (one packet per
+4096 seconds). Note that with values below \-4 the rate limiting is coarse
+(responses are allowed in bursts, even if the interval between them is shorter
+than the specified interval).
+.RE
+.sp
+\fBburst\fP \fIresponses\fP
+.RS 4
+This option sets the maximum number of responses that can be sent in a burst,
+temporarily exceeding the limit specified by the \fBinterval\fP option. This is
+useful for clients that make rapid measurements on start (e.g. \fBchronyd\fP with
+the \fBiburst\fP option). The default value is 8. The minimum value is 1 and the
+maximum value is 255.
+.RE
+.sp
+\fBleak\fP \fIrate\fP
+.RS 4
+This option sets the rate at which responses are randomly allowed even if the
+limits specified by the \fBinterval\fP and \fBburst\fP options are exceeded. This is
+necessary to prevent an attacker who is sending requests with a spoofed
+source address from completely blocking responses to that address. The leak
+rate is defined as a power of 1/2 and it is 2 by default, i.e. on average at
+least every fourth request has a response. The minimum value is 1 and the
+maximum value is 4.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+An example use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ratelimit interval 1 burst 16
+.fam
+.fi
+.if n .RE
+.sp
+This would reduce the response rate for IP addresses sending packets on average
+more than once per 2 seconds, or sending packets in bursts of more than 16
+packets, by up to 75% (with default \fBleak\fP of 2).
+.RE
+.sp
+\fBntsratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables rate limiting of NTS\-KE requests. It is similar to the
+\fBratelimit\fP directive, except the default interval is 6
+(1 connection per 64 seconds).
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsratelimit interval 3 burst 1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsmoothtime\fP \fImax\-freq\fP \fImax\-wander\fP [\fBleaponly\fP]
+.RS 4
+The \fBsmoothtime\fP directive can be used to enable smoothing of the time that
+\fBchronyd\fP serves to its clients to make it easier for them to track it and keep
+their clocks close together even when large offset or frequency corrections are
+applied to the server\(cqs clock, for example after being offline for a longer
+time.
+.sp
+BE WARNED: The server is intentionally not serving its best estimate of the
+true time. If a large offset has been accumulated, it can take a very long time
+to smooth it out. This directive should be used only when the clients are not
+configured to also poll another NTP server, because they could reject this
+server as a falseticker or fail to select a source completely.
+.sp
+The smoothing process is implemented with a quadratic spline function with two
+or three pieces. It is independent from any slewing applied to the local system
+clock, but the accumulated offset and frequency will be reset when the clock is
+corrected by stepping, e.g. by the \fBmakestep\fP directive or the
+\fBmakestep\fP command in \fBchronyc\fP. The process can be
+reset without stepping the clock by the \fBsmoothtime
+reset\fP command.
+.sp
+The first two arguments of the directive are the maximum frequency offset of
+the smoothed time to the tracked NTP time (in ppm) and the maximum rate at
+which the frequency offset is allowed to change (in ppm per second). \fBleaponly\fP
+is an optional third argument which enables a mode where only leap seconds are
+smoothed out and normal offset and frequency changes are ignored. The \fBleaponly\fP
+option is useful in a combination with the \fBleapsecmode slew\fP
+directive to allow the clients to use multiple time smoothing servers safely.
+.sp
+The smoothing process is activated automatically when 1/10000 of the estimated
+skew of the local clock falls below the maximum rate of frequency change. It
+can be also activated manually by the \fBsmoothtime
+activate\fP command, which is particularly useful when the clock is
+synchronised only with manual input and the skew is always larger than the
+threshold. The \fBsmoothing\fP command can be used to
+monitor the process.
+.sp
+An example suitable for clients using \fBntpd\fP and 1024 second polling interval
+could be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+smoothtime 400 0.001
+.fam
+.fi
+.if n .RE
+.sp
+An example suitable for clients using \fBchronyd\fP on Linux could be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+smoothtime 50000 0.01
+.fam
+.fi
+.if n .RE
+.RE
+.SS "Command and monitoring access"
+.sp
+\fBbindcmdaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindcmdaddress\fP directive specifies a local IP address to which \fBchronyd\fP
+will bind the UDP socket listening for monitoring command packets (issued
+by \fBchronyc\fP). On systems other than Linux, the address of the interface needs
+to be already configured when \fBchronyd\fP is started.
+.sp
+This directive can also change the path of the Unix domain command socket,
+which is used by \fBchronyc\fP to send configuration commands. The socket must be
+in a directory that is accessible only by the root or \fIchrony\fP user. The
+directory will be created on start if it does not exist. The compiled\-in default
+path of the socket is \fI@CHRONYRUNDIR@/chronyd.sock\fP. The socket can be
+disabled by setting the path to \fI/\fP.
+.sp
+By default, \fBchronyd\fP binds the UDP sockets to the addresses \fI127.0.0.1\fP and
+\fI::1\fP (i.e. the loopback interface). This blocks all access except from
+localhost. To listen for command packets on all interfaces, you can add the
+lines:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmdaddress 0.0.0.0
+bindcmdaddress ::
+.fam
+.fi
+.if n .RE
+.sp
+to the configuration file.
+.sp
+For each of the IPv4, IPv6, and Unix domain protocols, only one
+\fBbindcmdaddress\fP directive can be specified.
+.sp
+An example that sets the path of the Unix domain command socket is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmdaddress /var/run/chrony/chronyd.sock
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBbindcmddevice\fP \fIinterface\fP
+.RS 4
+The \fBbindcmddevice\fP directive binds the UDP command sockets to a network device
+specified by the interface name. This directive can specify only one interface
+and it is supported on Linux only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmddevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcmdallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP directive, except that it allows
+monitoring access (rather than NTP client access) to a particular subnet or
+host. (By \(oqmonitoring access\(cq is meant that \fBchronyc\fP can be run on those
+hosts and retrieve monitoring data from \fBchronyd\fP on this computer.)
+.sp
+The syntax is identical to the \fBallow\fP directive.
+.sp
+There is also a \fBcmdallow all\fP directive with similar behaviour to the \fBallow
+all\fP directive (but applying to monitoring access in this case, of course).
+.sp
+Note that \fBchronyd\fP has to be configured with the
+\fBbindcmdaddress\fP directive to not listen only on the
+loopback interface to actually allow remote access.
+.RE
+.sp
+\fBcmddeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBcmdallow\fP directive, except that it denies
+monitoring access to a particular subnet or host, rather than allowing it.
+.sp
+The syntax is identical.
+.sp
+There is also a \fBcmddeny all\fP directive with similar behaviour to the \fBcmdallow
+all\fP directive.
+.RE
+.sp
+\fBcmdport\fP \fIport\fP
+.RS 4
+The \fBcmdport\fP directive allows the port that is used for run\-time monitoring
+(via the \fBchronyc\fP program) to be altered from its default (323). If set to 0,
+\fBchronyd\fP will not open the port, this is useful to disable \fBchronyc\fP
+access from the Internet. (It does not disable the Unix domain command socket.)
+.sp
+An example shows the syntax:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdport 257
+.fam
+.fi
+.if n .RE
+.sp
+This would make \fBchronyd\fP use UDP 257 as its command port. (\fBchronyc\fP would
+need to be run with the \fB\-p 257\fP switch to inter\-operate correctly.)
+.RE
+.sp
+\fBcmdratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables response rate limiting for command packets. It is
+similar to the \fBratelimit\fP directive, except responses to
+localhost are never limited and the default interval is \-4 (16 packets per
+second).
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdratelimit interval 2
+.fam
+.fi
+.if n .RE
+.RE
+.SS "Real\-time clock (RTC)"
+.sp
+\fBhwclockfile\fP \fIfile\fP
+.RS 4
+The \fBhwclockfile\fP directive sets the location of the adjtime file which is
+used by the \fBhwclock\fP program on Linux. \fBchronyd\fP parses the file to find out
+if the RTC keeps local time or UTC. It overrides the \fBrtconutc\fP
+directive.
+.sp
+The compiled\-in default value is \(aq\fI@DEFAULT_HWCLOCK_FILE@\fP\(aq.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+hwclockfile /etc/adjtime
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBrtcautotrim\fP \fIthreshold\fP
+.RS 4
+The \fBrtcautotrim\fP directive is used to keep the RTC close to the system clock
+automatically. When the system clock is synchronised and the estimated error
+between the two clocks is larger than the specified threshold, \fBchronyd\fP will
+trim the RTC as if the \fBtrimrtc\fP command in \fBchronyc\fP
+was issued. The trimming operation is accurate to only about 1 second, which is
+the minimum effective threshold.
+.sp
+This directive is effective only with the \fBrtcfile\fP directive.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+rtcautotrim 30
+.fam
+.fi
+.if n .RE
+.sp
+This would set the threshold error to 30 seconds.
+.RE
+.sp
+\fBrtcdevice\fP \fIdevice\fP
+.RS 4
+The \fBrtcdevice\fP directive sets the path to the device file for accessing the
+RTC. The default path is \fI@DEFAULT_RTC_DEVICE@\fP.
+.RE
+.sp
+\fBrtcfile\fP \fIfile\fP
+.RS 4
+The \fBrtcfile\fP directive defines the name of the file in which \fBchronyd\fP can
+save parameters associated with tracking the accuracy of the RTC.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+rtcfile @CHRONYVARDIR@/rtc
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP saves information in this file when it exits and when the \fBwritertc\fP
+command is issued in \fBchronyc\fP. The information saved is the RTC\(cqs error at
+some epoch, that epoch (in seconds since January 1 1970), and the rate at which
+the RTC gains or loses time.
+.sp
+So far, the support for real\-time clocks is limited; their code is even more
+system\-specific than the rest of the software. You can only use the RTC
+facilities (the \fBrtcfile\fP directive and the \fB\-s\fP command\-line
+option to \fBchronyd\fP) if the following three conditions apply:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+You are running Linux.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The kernel is compiled with extended real\-time clock support (i.e. the
+\fI/dev/rtc\fP device is capable of doing useful things).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+You do not have other applications that need to make use of \fI/dev/rtc\fP at all.
+.RE
+.RE
+.sp
+\fBrtconutc\fP
+.RS 4
+\fBchronyd\fP assumes by default that the RTC keeps local time (including any
+daylight saving changes). This is convenient on PCs running Linux which are
+dual\-booted with Windows.
+.sp
+If you keep the RTC on local time and your computer is off when daylight saving
+(summer time) starts or ends, the computer\(cqs system time will be one hour in
+error when you next boot and start chronyd.
+.sp
+An alternative is for the RTC to keep Universal Coordinated Time (UTC). This
+does not suffer from the 1 hour problem when daylight saving starts or ends.
+.sp
+If the \fBrtconutc\fP directive appears, it means the RTC is required to keep UTC.
+The directive takes no arguments. It is equivalent to specifying the \fB\-u\fP
+switch to the Linux \fBhwclock\fP program.
+.sp
+Note that this setting is overridden by the \fBhwclockfile\fP file
+and is not relevant for the \fBrtcsync\fP directive.
+.RE
+.sp
+\fBrtcsync\fP
+.RS 4
+The \fBrtcsync\fP directive enables a mode where the system time is periodically
+copied to the RTC and \fBchronyd\fP does not try to track its drift. This directive
+cannot be used with the \fBrtcfile\fP directive.
+.sp
+On Linux, the RTC copy is performed by the kernel every 11 minutes.
+.sp
+On macOS, \fBchronyd\fP will perform the RTC copy every 60 minutes
+when the system clock is in a synchronised state.
+.sp
+On other systems this directive does nothing.
+.RE
+.SS "Logging"
+.sp
+\fBlog\fP [\fIoption\fP]...
+.RS 4
+The \fBlog\fP directive indicates that certain information is to be logged.
+The log files are written to the directory specified by the \fBlogdir\fP
+directive. A banner is periodically written to the files to indicate the
+meanings of the columns.
+.sp
+\fBrawmeasurements\fP
+.RS 4
+This option logs the raw NTP measurements and related information to a file
+called \fImeasurements.log\fP. An entry is made for each packet received from the
+source. This can be useful when debugging a problem. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2016\-11\-09 05:40:50 203.0.113.15    N  2 111 111 1111  10 10 1.0 \(rs
+   \-4.966e\-03  2.296e\-01  1.577e\-05  1.615e\-01  7.446e\-03 CB00717B 4B D K
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-10\-13]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address of server or peer from which measurement came [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of the current
+month has 61 seconds, \fI\-\fP means that the last minute of the month has 59
+seconds, \fI?\fP means the remote computer is not currently synchronised.) [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Stratum of remote computer. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+RFC 5905 tests 1 through 3 (1=pass, 0=fail) [111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+RFC 5905 tests 5 through 7 (1=pass, 0=fail) [111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Results of the \fBmaxdelay\fP, \fBmaxdelayratio\fP, and \fBmaxdelaydevratio\fP (or
+\fBmaxdelayquant\fP) tests, and a test for synchronisation loop (1=pass,
+0=fail). The first test from these four also checks the server precision,
+response time, and whether an interleaved response is acceptable for
+synchronisation. [1111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Local poll [10]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+Remote poll [10]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+\(oqScore\(cq (an internal score within each polling level used to decide when to
+increase or decrease the polling level. This is adjusted based on number of
+measurements currently being used for the regression algorithm). [1.0]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The estimated local clock error (\fItheta\fP in RFC 5905). Positive indicates
+that the local clock is slow of the remote source. [\-4.966e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The peer delay (\fIdelta\fP in RFC 5905). [2.296e\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 14.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 14." 4.2
+.\}
+The peer dispersion (\fIepsilon\fP in RFC 5905). [1.577e\-05]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 15.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 15." 4.2
+.\}
+The root delay (\fIDELTA\fP in RFC 5905). [1.615e\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 16.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 16." 4.2
+.\}
+The root dispersion (\fIEPSILON\fP in RFC 5905). [7.446e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 17.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 17." 4.2
+.\}
+Reference ID of the server\(cqs source as a hexadecimal number. [CB00717B]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 18.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 18." 4.2
+.\}
+NTP mode of the received packet (\fI1\fP=active peer, \fI2\fP=passive peer,
+\fI4\fP=server, \fIB\fP=basic, \fII\fP=interleaved). [4B]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 19.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 19." 4.2
+.\}
+Source of the local transmit timestamp
+(\fID\fP=daemon, \fIK\fP=kernel, \fIH\fP=hardware). [D]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 20.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 20." 4.2
+.\}
+Source of the local receive timestamp
+(\fID\fP=daemon, \fIK\fP=kernel, \fIH\fP=hardware). [K]
+.RE
+.RE
+.sp
+\fBmeasurements\fP
+.RS 4
+This option is identical to the \fBrawmeasurements\fP option, except it logs only
+valid measurements from synchronised sources, i.e. measurements which passed
+the RFC 5905 tests 1 through 7. This can be useful for producing graphs of the
+source\(cqs performance.
+.RE
+.sp
+\fBstatistics\fP
+.RS 4
+This option logs information about the regression processing to a file called
+\fIstatistics.log\fP. An example line (which actually appears as a single line in
+the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2016\-08\-10 05:40:50 203.0.113.15     6.261e\-03 \-3.247e\-03 \(rs
+     2.220e\-03  1.874e\-06  1.080e\-06 7.8e\-02  16   0   8  0.00
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-07\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address of server or peer from which measurement comes [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The estimated standard deviation of the measurements from the source (in
+seconds). [6.261e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The estimated offset of the source (in seconds, positive means the local
+clock is estimated to be fast, in this case). [\-3.247e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The estimated standard deviation of the offset estimate (in seconds).
+[2.220e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The estimated rate at which the local clock is gaining or losing time
+relative to the source (in seconds per second, positive means the local clock
+is gaining). This is relative to the compensation currently being applied to
+the local clock, \fInot\fP to the local clock without any compensation.
+[1.874e\-06]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The estimated error in the rate value (in seconds per second). [1.080e\-06].
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The ratio of |old_rate \- new_rate| / old_rate_error. Large values
+indicate the statistics are not modelling the source very well. [7.8e\-02]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+The number of measurements currently being used for the regression
+algorithm. [16]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+The new starting index (the oldest sample has index 0; this is the method
+used to prune old samples when it no longer looks like the measurements fit a
+linear model). [0, i.e. no samples discarded this time]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The number of runs. The number of runs of regression residuals with the same
+sign is computed. If this is too small it indicates that the measurements are
+no longer represented well by a linear model and that some older samples need
+to be discarded. The number of runs for the data that is being retained is
+tabulated. Values of approximately half the number of samples are expected.
+[8]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The estimated or configured asymmetry of network jitter on the path to the
+source which was used to correct the measured offsets. The asymmetry can be
+between \-0.5 and +0.5. A negative value means the delay of packets sent to
+the source is more variable than the delay of packets sent from the source
+back. [0.00, i.e. no correction for asymmetry]
+.RE
+.RE
+.sp
+\fBselection\fP
+.RS 4
+This option logs information about selection of sources for synchronisation to
+a file called \fIselection.log\fP. Note that the rate of entries written to this
+file grows quadratically with the number of specified sources (each measurement
+triggers the selection for all sources). An example line (which actually
+appears as a single line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2022\-05\-01 02:01:20 203.0.113.15    * \-\-\-\-\-  377  1.00  \(rs
+     4.228e+01 \-1.575e\-04  1.239e\-04
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2022\-05\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [02:01:20]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address or reference ID of the source. [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+State of the source indicated with one of the following symbols. [*]
+.sp
+
+.RS 4
+Not considered selectable for synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP \- has the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIs\fP \- is not synchronised.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIM\fP \- does not have enough measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fId\fP \- has a root distance larger than the maximum distance (configured by the
+\fBmaxdistance\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP \- has a jitter larger than the maximum jitter (configured by the
+\fBmaxjitter\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIw\fP \- waits for other sources to get out of the \fIM\fP state.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIS\fP \- has older measurements than other sources.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIO\fP \- has a stratum equal or larger than the orphan stratum (configured by
+the \fBlocal\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP \- does not fully agree with sources that have the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP \- does not agree with other sources (falseticker).
+.RE
+.RE
+.sp
+
+.RS 4
+Considered selectable for synchronisation, but not currently used:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIW\fP \- waits for other sources to be selectable (required by the
+\fBminsources\fP directive, or the \fBrequire\fP option of
+another source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP \- another selectable source is preferred due to the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIU\fP \- waits for a new measurement (after selecting a different best source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fID\fP \- has, or recently had, a root distance which is too large to be combined
+with other sources (configured by the \fBcombinelimit\fP
+directive).
+.RE
+.RE
+.sp
+
+.RS 4
+Used for synchronisation of the local clock:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP \- combined with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP \- selected as the best source to update the reference data (e.g. root
+delay, root dispersion).
+.RE
+.RE
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Reachability register printed as an octal number. The register has 8 bits and
+is updated on every received or missed packet from the source. A value of 377
+indicates that a valid reply was received for all from the last eight
+transmissions. [377]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Current score against the source in the \fI*\fP state. The scoring system avoids
+frequent reselection when multiple sources have a similar root distance. A
+value larger than 1 indicates this source was better than the \fI*\fP source in
+recent selections. If the score reaches 10, the best source will be reselected
+and the scores will be reset to 1. [1.00]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+Interval since the last measurement of the source in seconds. [4.228e+01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Lower endpoint of the interval which was expected to contain the true offset
+of the local clock determined by the root distance of the source. [\-1.575e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Upper endpoint of the interval which was expected to contain the true offset
+of the local clock determined by the root distance of the source. [1.239e\-04]
+.RE
+.RE
+.sp
+\fBtracking\fP
+.RS 4
+This option logs changes to the estimate of the system\(cqs gain or loss rate, and
+any slews made, to a file called \fItracking.log\fP. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2017\-08\-22 13:22:36 203.0.113.15     2     \-3.541      0.075 \-8.621e\-06 N \(rs
+            2  2.940e\-03 \-2.084e\-04  1.534e\-02  3.472e\-04  8.304e\-03
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the
+values from the example line above) :
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2017\-08\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [13:22:36]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The IP address of the server or peer to which the local system is synchronised.
+[203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The stratum of the local system. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The local system frequency (in ppm, positive means the local system runs fast
+of UTC). [\-3.541]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The error bounds on the frequency (in ppm). [0.075]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The estimated local offset at the epoch, which is normally corrected by
+slewing the local clock (in seconds, positive indicates the clock is fast of
+UTC). [\-8.621e\-06]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of this month
+has 61 seconds, \fI\-\fP means that the last minute of the month has 59 seconds,
+\fI?\fP means the clock is not currently synchronised.) [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The number of combined sources. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+The estimated standard deviation of the combined offset (in seconds).
+[2.940e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+The remaining offset correction from the previous update (in seconds,
+positive means the system clock is slow of UTC). [\-2.084e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The total of the network path delays to the reference clock to which
+the local clock is ultimately synchronised (in seconds). [1.534e\-02]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The total dispersion accumulated through all the servers back to the
+reference clock to which the local clock is ultimately synchronised
+(in seconds). [3.472e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 14.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 14." 4.2
+.\}
+The maximum estimated error of the system clock in the interval since the
+previous update (in seconds). It includes the offset, remaining offset
+correction, root delay, and dispersion from the previous update with the
+dispersion which accumulated in the interval. [8.304e\-03]
+.RE
+.RE
+.sp
+\fBrtc\fP
+.RS 4
+This option logs information about the system\(cqs real\-time clock. An example
+line (which actually appears as a single line in the file) from the \fIrtc.log\fP
+file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2015\-07\-22 05:40:50     \-0.037360 1       \-0.037434\(rs
+          \-37.948  12   5  120
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the
+values from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-07\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The measured offset between the RTC and the system clock in seconds.
+Positive indicates that the RTC is fast of the system time [\-0.037360].
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Flag indicating whether the regression has produced valid coefficients.
+(1 for yes, 0 for no). [1]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Offset at the current time predicted by the regression process. A large
+difference between this value and the measured offset tends to indicate that
+the measurement is an outlier with a serious measurement error. [\-0.037434]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The rate at which the RTC is losing or gaining time relative to the system
+clock. In ppm, with positive indicating that the RTC is gaining time.
+[\-37.948]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The number of measurements used in the regression. [12]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The number of runs of regression residuals of the same sign. Low values
+indicate that a straight line is no longer a good model of the measured data
+and that older measurements should be discarded. [5]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The measurement interval used prior to the measurement being made (in
+seconds). [120]
+.RE
+.RE
+.sp
+\fBrefclocks\fP
+.RS 4
+This option logs the raw and filtered reference clock measurements to a file
+called \fIrefclocks.log\fP. An example line (which actually appears as a single
+line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2009\-11\-30 14:33:27.000000 PPS2    7 N 1  4.900000e\-07 \-6.741777e\-07  1.000e\-06
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2009\-11\-30]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second.Microsecond. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [14:33:27.000000]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Reference ID of the reference clock from which the measurement came. [PPS2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Sequence number of driver poll within one polling interval for raw samples,
+or \fI\-\fP for filtered samples. [7]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of the current
+month has 61 seconds, \fI\-\fP means that the last minute of the month has 59
+seconds). [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Flag indicating whether the sample comes from PPS source. (1 for yes,
+0 for no, or \fI\-\fP for filtered sample). [1]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+Local clock error measured by reference clock driver, or \fI\-\fP for filtered sample.
+[4.900000e\-07]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Local clock error with applied corrections. Positive indicates that the local
+clock is slow. [\-6.741777e\-07]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Assumed dispersion of the sample. [1.000e\-06]
+.RE
+.RE
+.sp
+\fBtempcomp\fP
+.RS 4
+This option logs the temperature measurements and system rate compensations to
+a file called \fItempcomp.log\fP. An example line (which actually appears as a
+single line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2015\-04\-19 10:39:48  2.8000e+04  3.6600e\-01
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-04\-19]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [10:39:48]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Temperature read from the sensor. [2.8000e+04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Applied compensation in ppm, positive means the system clock is running
+faster than it would be without the compensation. [3.6600e\-01]
+.RE
+.RE
+.RE
+.sp
+
+.RS 4
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+log measurements statistics tracking
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBlogbanner\fP \fIentries\fP
+.RS 4
+A banner is periodically written to the log files enabled by the \fBlog\fP
+directive to indicate the meanings of the columns.
+.sp
+The \fBlogbanner\fP directive specifies after how many entries in the log file
+should be the banner written. The default is 32, and 0 can be used to disable
+it entirely.
+.RE
+.sp
+\fBlogchange\fP \fIthreshold\fP
+.RS 4
+This directive sets the threshold for the adjustment of the system clock that
+will generate a syslog message. Clock errors detected via NTP packets,
+reference clocks, or timestamps entered via the
+\fBsettime\fP command of \fBchronyc\fP are logged.
+.sp
+By default, the threshold is 1 second.
+.sp
+An example of the use is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+logchange 0.1
+.fam
+.fi
+.if n .RE
+.sp
+which would cause a syslog message to be generated if a system clock error of over
+0.1 seconds starts to be compensated.
+.RE
+.sp
+\fBlogdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies the directory for writing log files enabled by the
+\fBlog\fP directive. If the directory does not exist, it will be created
+automatically.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+logdir /var/log/chrony
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmailonchange\fP \fIemail\fP \fIthreshold\fP
+.RS 4
+This directive defines an email address to which mail should be sent if
+\fBchronyd\fP applies a correction exceeding a particular threshold to the system
+clock.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+mailonchange root@localhost 0.5
+.fam
+.fi
+.if n .RE
+.sp
+This would send a mail message to root if a change of more than 0.5 seconds
+were applied to the system clock.
+.sp
+This directive cannot be used when a system call filter is enabled by the \fB\-F\fP
+option as the \fBchronyd\fP process will not be allowed to fork and execute the
+sendmail binary.
+.RE
+.SS "Miscellaneous"
+.sp
+\fBconfdir\fP \fIdirectory\fP...
+.RS 4
+The \fBconfdir\fP directive includes configuration files with the \fI.conf\fP suffix
+from a directory. The files are included in the lexicographical order of the
+file names.
+.sp
+Multiple directories (up to 10) can be specified with a single \fBconfdir\fP
+directive. In this case, if multiple directories contain a file with the same
+name, only the first file in the order of the specified directories will be
+included. This enables a fragmented configuration where existing fragments can
+be replaced by adding files to a different directory.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+confdir @SYSCONFDIR@/chrony.d
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsourcedir\fP \fIdirectory\fP...
+.RS 4
+The \fBsourcedir\fP directive is identical to the \fBconfdir\fP directive, except the
+configuration files have the \fI.sources\fP suffix, they can only specify NTP
+sources (i.e. the \fBserver\fP, \fBpool\fP, and \fBpeer\fP directives), they are expected
+to have all lines terminated by the newline character, and they can be
+reloaded by the \fBreload sources\fP command in
+\fBchronyc\fP. It is particularly useful with dynamic sources like NTP servers
+received from a DHCP server, which can be written to a file specific to the
+network interface by a networking script.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+sourcedir /var/run/chrony\-dhcp
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBinclude\fP \fIpattern\fP
+.RS 4
+The \fBinclude\fP directive includes a configuration file, or multiple configuration
+files if a wildcard pattern is specified. Unlike with the \fBconfdir\fP directive,
+the full name of the files needs to be specified and at least one file is
+required to exist.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+include @SYSCONFDIR@/chrony.d/*.conf
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBhwtimestamp\fP \fIinterface\fP [\fIoption\fP]...
+.RS 4
+This directive enables hardware timestamping of NTP packets sent to and
+received from the specified network interface. The network interface controller
+(NIC) uses its own clock to accurately timestamp the actual transmissions and
+receptions, avoiding processing and queueing delays in the kernel, network
+driver, and hardware. This can significantly improve the accuracy of the
+timestamps and the measured offset, which is used for synchronisation of the
+system clock. In order to get the best results, both sides receiving and
+sending NTP packets (i.e. server and client, or two peers) need to use HW
+timestamping. If the server or peer supports the interleaved mode, it needs to
+be enabled by the \fBxleave\fP option in the \fBserver\fP or the
+\fBpeer\fP directive.
+.sp
+This directive is supported on Linux 3.19 and newer. The NIC must support HW
+timestamping, which can be verified with the \fBethtool \-T\fP command. The list of
+capabilities should include \fIhardware\-raw\-clock\fP, \fIhardware\-transmit\fP, and
+\fIhardware\-receive\fP. The receive filter \fIall\fP, or \fIntp\fP, is necessary for
+timestamping of received NTP packets. Timestamping of packets received on
+bridged and bonded interfaces is supported on Linux 4.13 and newer. If HW
+timestamping does not work for received packets, \fBchronyd\fP will use kernel
+receive timestamps instead. Transmit\-only HW timestamping can still be useful
+to improve stability of the synchronisation.
+.sp
+\fBchronyd\fP does not synchronise the NIC clock. It assumes the clock is running
+free. Multiple instances of \fBchronyd\fP can use the same interface with enabled
+HW timestamping. Applications which need HW timestamping with a synchronised
+clock (e.g. a PTP daemon) should use a virtual clock running on top of the
+physical clock created by writing to \fI/sys/class/ptp/ptpX/n_vclocks\fP. This
+feature is available on Linux 5.14 and newer.
+.sp
+If the kernel supports software timestamping, it will be enabled for all
+interfaces. The source of timestamps (i.e. hardware, kernel, or daemon) is
+indicated in the \fImeasurements.log\fP file if enabled by the \fBlog
+measurements\fP directive, and the \fBntpdata\fP report in
+\fBchronyc\fP.
+.sp
+This directive can be used multiple times to enable HW timestamping on multiple
+interfaces. If the specified interface is \fI*\fP, \fBchronyd\fP will try to enable HW
+timestamping on all available interfaces.
+.sp
+The \fBhwtimestamp\fP directive has the following options:
+.sp
+\fBminpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the minimum interval between readings of the NIC clock.
+It\(cqs defined as a power of two. It should correspond to the minimum polling
+interval of all NTP sources and the minimum expected polling interval of NTP
+clients. The default value is 0 (1 second) and the minimum value is \-6 (1/64th
+of a second).
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+This option specifies the minimum number of readings kept for tracking of the
+NIC clock. The default value is 2.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+This option specifies the maximum number of readings kept for tracking of the
+NIC clock. The default value is 16.
+.RE
+.sp
+\fBprecision\fP \fIprecision\fP
+.RS 4
+This option specifies the assumed precision of reading of the NIC clock. The
+default value is 100e\-9 (100 nanoseconds).
+.RE
+.sp
+\fBtxcomp\fP \fIcompensation\fP
+.RS 4
+This option specifies the difference in seconds between the actual transmission
+time at the physical layer and the reported transmit timestamp. This value will
+be added to transmit timestamps obtained from the NIC. The default value is 0.
+.RE
+.sp
+\fBrxcomp\fP \fIcompensation\fP
+.RS 4
+This option specifies the difference in seconds between the reported receive
+timestamp and the actual reception time at the physical layer. This value will
+be subtracted from receive timestamps obtained from the NIC. The default value
+is 0.
+.RE
+.sp
+\fBnocrossts\fP
+.RS 4
+Some hardware can precisely cross timestamp the NIC clock with the system
+clock. This option disables the use of the cross timestamping.
+.RE
+.sp
+\fBrxfilter\fP \fIfilter\fP
+.RS 4
+This option selects the receive timestamping filter. The \fIfilter\fP can be one of
+the following:
+.sp
+\fIall\fP
+.RS 4
+Enables timestamping of all received packets.
+.RE
+.sp
+\fIntp\fP
+.RS 4
+Enables timestamping of received NTP packets.
+.RE
+.sp
+\fIptp\fP
+.RS 4
+Enables timestamping of received PTP packets.
+.RE
+.sp
+\fInone\fP
+.RS 4
+Disables timestamping of received packets.
+.RE
+.RE
+.sp
+
+.RS 4
+The most specific filter for timestamping of NTP packets supported by the NIC
+is selected by default. Some NICs can timestamp PTP packets only. By default,
+they will be configured with the \fInone\fP filter and expected to provide hardware
+timestamps for transmitted packets only. Timestamping of PTP packets is useful
+with NTP\-over\-PTP enabled by the \fBptpport\fP
+directive, or when another application is receiving PTP packets on the
+interface. Forcing timestamping of all packets with the \fIall\fP filter could be
+useful if the NIC supported both the \fIall\fP and \fIntp\fP filters, and it should
+timestamp both NTP and PTP packets, or NTP packets on a different UDP port.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Examples of the directive are:
+.sp
+.if n .RS 4
+.nf
+.fam C
+hwtimestamp eth0
+hwtimestamp eth1 txcomp 300e\-9 rxcomp 645e\-9
+hwtimestamp *
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBkeyfile\fP \fIfile\fP
+.RS 4
+This directive is used to specify the location of the file containing symmetric
+keys which are shared between NTP servers and clients, or peers, in order to
+authenticate NTP packets with a message authentication code (MAC) using a
+cryptographic hash function or cipher.
+.sp
+The format of the directive is shown in the example below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keyfile @SYSCONFDIR@/chrony.keys
+.fam
+.fi
+.if n .RE
+.sp
+The argument is simply the name of the file containing the ID\-key pairs. The
+format of the file is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+10 tulip
+11 hyacinth
+20 MD5 ASCII:crocus
+25 SHA1 HEX:933F62BE1D604E68A81B557F18CFA200483F5B70
+30 AES128 HEX:7EA62AE64D190114D46D5A082F948EC1
+31 AES256 HEX:37DDCBC67BB902BCB8E995977FAB4D2B5642F5B32EBCEEE421921D97E5CBFE39
+ ...
+.fam
+.fi
+.if n .RE
+.sp
+Each line consists of an ID, optional type, and key.
+.sp
+The ID can be any positive integer in the range 1 through 2^32\-1.
+.sp
+The type is a name of a cryptographic hash function or cipher which is used to
+generate and verify the MAC. The default type is \fBMD5\fP, which is always
+supported.
+If \fBchronyd\fP was built with enabled support for hashing using a crypto library
+(Nettle, GnuTLS, NSS, or LibTomCrypt), the following functions are available: \fBMD5\fP,
+\fBSHA1\fP, \fBSHA256\fP, \fBSHA384\fP, \fBSHA512\fP. Depending on which library and version is
+\fBchronyd\fP using, some of the following hash functions and ciphers may
+also be available:
+\fBSHA3\-224\fP, \fBSHA3\-256\fP, \fBSHA3\-384\fP, \fBSHA3\-512\fP, \fBTIGER\fP, \fBWHIRLPOOL\fP, \fBAES128\fP,
+\fBAES256\fP.
+.sp
+The key can be specified as a string of ASCII characters not containing white
+space with an optional \fBASCII:\fP prefix, or as a hexadecimal number with the
+\fBHEX:\fP prefix. The maximum length of the line is 2047 characters.
+If the type is a cipher, the length of the key must match the cipher (i.e. 128
+bits for AES128 and 256 bits for AES256).
+.sp
+It is recommended to use randomly generated keys, specified in the hexadecimal
+format, which are at least 128 bits long (i.e. they have at least 32 characters
+after the \fBHEX:\fP prefix). \fBchronyd\fP will log a warning to syslog on start if a
+source is specified in the configuration file with a key shorter than 80 bits.
+.sp
+The recommended key types are AES ciphers and SHA3 hash functions. MD5 should
+be avoided unless no other type is supported on the server and client, or
+peers.
+.sp
+The \fBkeygen\fP command of \fBchronyc\fP can be used to
+generate random keys for the key file. By default, it generates 160\-bit MD5 or
+SHA1 keys.
+.sp
+For security reasons, the file should be readable only by root and the user
+under which \fBchronyd\fP is normally running (to allow \fBchronyd\fP to re\-read the
+file when the \fBrekey\fP command is issued by \fBchronyc\fP).
+.RE
+.sp
+\fBlock_all\fP
+.RS 4
+The \fBlock_all\fP directive will lock the \fBchronyd\fP process into RAM so that it
+will never be paged out. This can result in lower and more consistent latency.
+The directive is supported on Linux, FreeBSD, NetBSD, and illumos.
+.RE
+.sp
+\fBpidfile\fP \fIfile\fP
+.RS 4
+Unless \fBchronyd\fP is started with the \fB\-Q\fP option, it writes its process ID
+(PID) to a file, and checks this file on startup to see if another \fBchronyd\fP
+might already be running on the system. By default, the file used is
+\fI@DEFAULT_PID_FILE@\fP. The \fBpidfile\fP directive allows the name to be changed,
+e.g.:
+.sp
+.if n .RS 4
+.nf
+.fam C
+pidfile /run/chronyd.pid
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBptpport\fP \fIport\fP
+.RS 4
+The \fBptpport\fP directive enables \fBchronyd\fP to send and receive NTP messages
+contained in PTP event messages (NTP\-over\-PTP) to enable hardware timestamping
+on NICs which cannot timestamp NTP packets, but can timestamp unicast PTP
+packets. The port recognized by the NICs is 319 (PTP event port). The default
+value is 0 (disabled).
+.sp
+The NTP\-over\-PTP support is experimental. The protocol and configuration can
+change in future. It should be used only in local networks and expected to work
+only between servers and clients running the same version of \fBchronyd\fP.
+.sp
+The PTP port will be open even if \fBchronyd\fP is not configured to operate as a
+server or client. The directive does not change the default protocol of
+specified NTP sources. Each NTP source that should use NTP\-over\-PTP needs to
+be specified with the \fBport\fP option set to the PTP port. To actually enable
+hardware timestamping on NICs which can timestamp PTP packets only, the
+\fBrxfilter\fP option of the \fBhwtimestamp\fP directive needs to be set to \fIptp\fP.
+.sp
+An example of client configuration is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net minpoll 0 maxpoll 0 xleave port 319
+hwtimestamp * rxfilter ptp
+ptpport 319
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsched_priority\fP \fIpriority\fP
+.RS 4
+On Linux, FreeBSD, NetBSD, and illumos, the \fBsched_priority\fP directive will
+select the SCHED_FIFO real\-time scheduler at the specified priority (which must
+be between 0 and 100). On macOS, this option must have either a value of 0 (the
+default) to disable the thread time constraint policy or 1 for the policy to be
+enabled.
+.sp
+On systems other than macOS, this directive uses the \fBpthread_setschedparam()\fP
+system call to instruct the kernel to use the SCHED_FIFO first\-in, first\-out
+real\-time scheduling policy for \fBchronyd\fP with the specified priority. This
+means that whenever \fBchronyd\fP is ready to run it will run, interrupting
+whatever else is running unless it is a higher priority real\-time process. This
+should not impact performance as \fBchronyd\fP resource requirements are modest,
+but it should result in lower and more consistent latency since \fBchronyd\fP will
+not need to wait for the scheduler to get around to running it. You should not
+use this unless you really need it. The \fBpthread_setschedparam(3)\fP man page has
+more details.
+.sp
+On macOS, this directive uses the \fBthread_policy_set()\fP kernel call to
+specify real\-time scheduling. As noted above, you should not use this directive
+unless you really need it.
+.RE
+.sp
+\fBuser\fP \fIuser\fP
+.RS 4
+The \fBuser\fP directive sets the name of the system user to which \fBchronyd\fP will
+switch after start in order to drop root privileges.
+.sp
+On Linux, \fBchronyd\fP needs to be compiled with support for the \fBlibcap\fP library.
+On macOS, FreeBSD, NetBSD and illumos \fBchronyd\fP forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+.sp
+The compiled\-in default value is \fI@DEFAULT_USER@\fP.
+.RE
+.SH "EXAMPLES"
+.SS "NTP client with permanent connection to NTP servers"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that are connected
+to the Internet (or to any network containing true NTP servers which ultimately
+derive their time from a reference clock) permanently or most of the time.
+.sp
+To operate in this mode, you will need to know the names of the NTP servers
+you want to use. You might be able to find names of suitable servers by one of
+the following methods:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Your institution might already operate servers on its network.
+Contact your system administrator to find out.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Your ISP probably has one or more NTP servers available for its
+customers.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Somewhere under the NTP homepage there is a list of public
+stratum 1 and stratum 2 servers. You should find one or more servers that are
+near to you. Check that their access policy allows you to use their
+facilities.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Use public servers from the \c
+.URL "https://www.pool.ntp.org/" "pool.ntp.org" ""
+project.
+.RE
+.sp
+Assuming that your NTP servers are called \fIfoo.example.net\fP, \fIbar.example.net\fP
+and \fIbaz.example.net\fP, your \fIchrony.conf\fP file could contain as a minimum:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net
+server bar.example.net
+server baz.example.net
+.fam
+.fi
+.if n .RE
+.sp
+However, you will probably want to include some of the other directives. The
+\fBdriftfile\fP, \fBmakestep\fP and \fBrtcsync\fP
+might be particularly useful. Also, the \fBiburst\fP option of the
+\fBserver\fP directive is useful to speed up the initial
+synchronisation. The smallest useful configuration file would look something
+like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+When using a pool of NTP servers (one name is used for multiple servers which
+might change over time), it is better to specify them with the \fBpool\fP
+directive instead of multiple \fBserver\fP directives. The configuration file could
+in this case look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+pool pool.ntp.org iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+If the servers (or pool) support the Network Time Security (NTS)
+authentication mechanism and \fBchronyd\fP is compiled with NTS support, the \fBnts\fP
+option will enable a secure synchronisation to the servers. The configuration
+file could look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst nts
+server bar.example.net iburst nts
+server baz.example.net iburst nts
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.SS "NTP client with infrequent connection to NTP servers"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that have
+occasional connections to NTP servers. In this case, you will need some
+additional configuration to tell \fBchronyd\fP when the connection goes up and
+down. This saves the program from continuously trying to poll the servers when
+they are inaccessible.
+.sp
+Again, assuming that your NTP servers are called \fIfoo.example.net\fP,
+\fIbar.example.net\fP and \fIbaz.example.net\fP, your \fIchrony.conf\fP file would now
+contain:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net offline
+server bar.example.net offline
+server baz.example.net offline
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The \fBoffline\fP keyword indicates that the servers start in an offline state, and
+that they should not be contacted until \fBchronyd\fP receives notification from
+\fBchronyc\fP that the link to the Internet is present. To tell \fBchronyd\fP when to
+start and finish sampling the servers, the \fBonline\fP and
+\fBoffline\fP commands of \fBchronyc\fP need to be used.
+.sp
+To give an example of their use, assuming that \fBpppd\fP is the program being
+used to connect to the Internet and that \fBchronyc\fP has been installed at
+\fI@BINDIR@/chronyc\fP, the script \fI/etc/ppp/ip\-up\fP would include:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc online
+.fam
+.fi
+.if n .RE
+.sp
+and the script \fI/etc/ppp/ip\-down\fP would include:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc offline
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP\(aqs polling of the servers would now only occur whilst the machine is
+actually connected to the Internet.
+.SS "Isolated networks"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that never have
+network connectivity to any computer which ultimately derives its time from a
+reference clock.
+.sp
+In this situation, one computer is selected to be the primary timeserver. The
+other computers are either direct clients of the server, or clients of clients.
+.sp
+The \fBlocal\fP directive enables a local reference mode, which allows
+\fBchronyd\fP to appear synchronised even when it is not.
+.sp
+The rate value in the server\(cqs drift file needs to be set to the average rate
+at which the server gains or loses time. \fBchronyd\fP includes support for this,
+in the form of the \fBmanual\fP directive and the
+\fBsettime\fP command in the \fBchronyc\fP program.
+.sp
+If the server is rebooted, \fBchronyd\fP can re\-read the drift rate from the drift
+file. However, the server has no accurate estimate of the current time. To get
+around this, the system can be configured so that the server can initially set
+itself to a \(oqmajority\-vote\(cq of selected clients\(aq times; this allows the
+clients to \(oqflywheel\(cq the server while it is rebooting.
+.sp
+The \fBsmoothtime\fP directive is useful when the clocks of the
+clients need to stay close together when the local time is adjusted by the
+\fBsettime\fP command. The smoothing process needs to be
+activated by the \fBsmoothtime activate\fP command when
+the local time is ready to be served. After that point, any adjustments will be
+smoothed out.
+.sp
+A typical configuration file for the server (called \fIntp.local\fP) might be
+(assuming the clients and the server are in the \fI192.168.165.x\fP subnet):
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 1 client1 client3 client6
+driftfile @CHRONYVARDIR@/drift
+local stratum 8
+manual
+allow 192.168.165.0/24
+smoothtime 400 0.01
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+For the clients that have to resynchronise the server when it restarts,
+the configuration file might be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server ntp.local iburst
+driftfile @CHRONYVARDIR@/drift
+allow 192.168.165.0/24
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The rest of the clients would be the same, except that the \fBallow\fP directive is
+not required.
+.sp
+If there is no suitable computer to be designated as the primary server, or
+there is a requirement to keep the clients synchronised even when it fails, the
+\fBorphan\fP option of the \fBlocal\fP directive enables a special mode where the
+server is selected from multiple computers automatically. They all need to use
+the same \fBlocal\fP configuration and poll one another. The server with the
+smallest reference ID (which is based on its IP address) will take the role of
+the primary server and others will be synchronised to it. When it fails, the
+server with the second smallest reference ID will take over and so on.
+.sp
+A configuration file for the first server might be (assuming there are three
+servers called \fIntp1.local\fP, \fIntp2.local\fP, and \fIntp3.local\fP):
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 1 ntp2.local ntp3.local
+server ntp2.local
+server ntp3.local
+driftfile @CHRONYVARDIR@/drift
+local stratum 8 orphan
+manual
+allow 192.168.165.0/24
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The other servers would be the same, except the hostnames in the \fBinitstepslew\fP
+and \fBserver\fP directives would be modified to specify the other servers. Their
+clients might be configured to poll all three servers.
+.SS "RTC tracking"
+.sp
+This section considers a computer which has occasional connections to the
+Internet and is turned off between \(oqsessions\(cq. In this case, \fBchronyd\fP relies
+on the computer\(cqs RTC to maintain the time between the periods when it is
+powered up. It assumes that Linux is run exclusively on the computer. Dual\-boot
+systems might work; it depends what (if anything) the other system does to the
+RTC. On 2.6 and later kernels, if your motherboard has a HPET, you will need to
+enable the \fBHPET_EMULATE_RTC\fP option in your kernel configuration. Otherwise,
+\fBchronyd\fP will not be able to interact with the RTC device and will give up
+using it.
+.sp
+When the computer is connected to the Internet, \fBchronyd\fP has access to
+external NTP servers which it makes measurements from. These measurements are
+saved, and straight\-line fits are performed on them to provide an estimate of
+the computer\(cqs time error and rate of gaining or losing time.
+.sp
+When the computer is taken offline from the Internet, the best estimate of the
+gain or loss rate is used to free\-run the computer until it next goes online.
+.sp
+Whilst the computer is running, \fBchronyd\fP makes measurements of the RTC (via
+the \fI/dev/rtc\fP interface, which must be compiled into the kernel). An estimate
+is made of the RTC error at a particular RTC second, and the rate at which the
+RTC gains or loses time relative to true time.
+.sp
+When the computer is powered down, the measurement histories for all the NTP
+servers are saved to files, and the RTC tracking information is also
+saved to a file (if the \fBrtcfile\fP directive has been specified).
+These pieces of information are also saved if the \fBdump\fP
+and \fBwritertc\fP commands respectively are issued
+through \fBchronyc\fP.
+.sp
+When the computer is rebooted, \fBchronyd\fP reads the current RTC time and the RTC
+information saved at the last shutdown. This information is used to set the
+system clock to the best estimate of what its time would have been now, had it
+been left running continuously. The measurement histories for the servers are
+then reloaded.
+.sp
+The next time the computer goes online, the previous sessions\(aq measurements can
+contribute to the line\-fitting process, which gives a much better estimate of
+the computer\(cqs gain or loss rate.
+.sp
+One problem with saving the measurements and RTC data when the machine is shut
+down is what happens if there is a power failure; the most recent data will not
+be saved. Although \fBchronyd\fP is robust enough to cope with this, some
+performance might be lost. (The main danger arises if the RTC has been changed
+during the session, with the \fBtrimrtc\fP command in \fBchronyc\fP. Because of this,
+\fBtrimrtc\fP will make sure that a meaningful RTC file is saved after the
+change is completed).
+.sp
+The easiest protection against power failure is to put the \fBdump\fP and
+\fBwritertc\fP commands in the same place as the \fBoffline\fP command is issued to
+take \fBchronyd\fP offline; because \fBchronyd\fP free\-runs between online sessions, no
+parameters will change significantly between going offline from the Internet
+and any power failure.
+.sp
+A final point regards computers which are left running for extended periods and
+where it is desired to spin down the hard disc when it is not in use (e.g. when
+not accessed for 15 minutes). \fBchronyd\fP has been planned so it supports such
+operation; this is the reason why the RTC tracking parameters are not saved to
+disc after every update, but only when the user requests such a write, or
+during the shutdown sequence. The only other facility that will generate
+periodic writes to the disc is the \fBlog rtc\fP facility in the configuration
+file; this option should not be used if you want your disc to spin down.
+.sp
+To illustrate how a computer might be configured for this case, example
+configuration files are shown.
+.sp
+For the \fIchrony.conf\fP file, the following can be used as an example.
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net maxdelay 0.4 offline
+server bar.example.net maxdelay 0.4 offline
+server baz.example.net maxdelay 0.4 offline
+logdir /var/log/chrony
+log statistics measurements tracking
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+maxupdateskew 100.0
+dumpdir @CHRONYVARDIR@
+rtcfile @CHRONYVARDIR@/rtc
+.fam
+.fi
+.if n .RE
+.sp
+\fBpppd\fP is used for connecting to the Internet. This runs two scripts
+\fI/etc/ppp/ip\-up\fP and \fI/etc/ppp/ip\-down\fP when the link goes online and offline
+respectively.
+.sp
+The relevant part of the \fI/etc/ppp/ip\-up\fP file is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc online
+.fam
+.fi
+.if n .RE
+.sp
+and the relevant part of the \fI/etc/ppp/ip\-down\fP script is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc \-m offline dump writertc
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP is started during the boot sequence with the \fB\-r\fP and \fB\-s\fP options.
+It might need to be started before any software that depends on the system clock
+not jumping or moving backwards, depending on the directives in \fBchronyd\fP\(aqs
+configuration file.
+.sp
+For the system shutdown, \fBchronyd\fP should receive a SIGTERM several seconds
+before the final SIGKILL; the SIGTERM causes the measurement histories and RTC
+information to be saved.
+.SS "Public NTP server"
+.sp
+\fBchronyd\fP can be configured to operate as a public NTP server, e.g. to join the
+.URL "https://www.pool.ntp.org/en/join.html" "pool.ntp.org" ""
+project. The configuration
+is similar to the NTP client with permanent connection, except it needs to
+allow client access from all addresses. It is recommended to find at least four
+good servers (e.g. from the pool, or on the NTP homepage). If the server has a
+hardware reference clock (e.g. a GPS receiver), it can be specified by the
+\fBrefclock\fP directive.
+.sp
+The amount of memory used for logging client accesses can be increased in order
+to enable clients to use the interleaved mode even when the server has a large
+number of clients, and better support rate limiting if it is enabled by the
+\fBratelimit\fP directive. The system timezone database, if it is
+kept up to date and includes the \fIright/UTC\fP timezone, can be used as a
+reliable source to determine when a leap second will be applied to UTC. The
+\fB\-r\fP option with the \fBdumpdir\fP directive shortens the time in which
+\fBchronyd\fP will not be able to serve time to its clients when it needs to be
+restarted (e.g. after upgrading to a newer version, or a change in the
+configuration).
+.sp
+The configuration file could look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+server qux.example.net iburst
+makestep 1.0 3
+rtcsync
+allow
+clientloglimit 100000000
+leapsectz right/UTC
+driftfile @CHRONYVARDIR@/drift
+dumpdir @CHRONYRUNDIR@
+.fam
+.fi
+.if n .RE
+.SH "SEE ALSO"
+.sp
+\fBchronyc(1)\fP, \fBchronyd(8)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony.tuxfamily.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/chronyc.adoc b/doc/chronyc.adoc
new file mode 100644
index 0000000..45d8548
--- /dev/null
+++ b/doc/chronyc.adoc
@@ -0,0 +1,1508 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Stephen Wadeley  2016
+// Copyright (C) Miroslav Lichvar  2009-2017, 2019-2022
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chronyc(1)
+:doctype: manpage
+:man manual: User manual
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+
+chronyc - command-line interface for chrony daemon
+
+== SYNOPSIS
+
+*chronyc* [_OPTION_]... [_COMMAND_]...
+
+== DESCRIPTION
+
+*chronyc* is a command-line interface program which can be used to monitor
+*chronyd*'s performance and to change various operating parameters whilst it is
+running.
+
+If no commands are specified on the command line, *chronyc* will expect input
+from the user. The prompt _chronyc>_ will be displayed when it is being run
+from a terminal. If *chronyc*'s input or output are redirected from or to a file,
+the prompt will not be shown.
+
+There are two ways *chronyc* can access *chronyd*. One is the Internet
+Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is
+accessible locally by the root or _chrony_ user. By default, *chronyc* first
+tries to connect to the Unix domain socket. The compiled-in default path is
+_@CHRONYRUNDIR@/chronyd.sock_. If that fails (e.g. because *chronyc* is
+running under a non-root user), it will try to connect to 127.0.0.1 and then
+::1.
+
+Only the following monitoring commands, which do not affect the behaviour of
+*chronyd*, are allowed from the network: *activity*, *manual list*,
+*rtcdata*, *smoothing*, *sourcename*, *sources*, *sourcestats*, *tracking*,
+*waitsync*. The
+set of hosts from which *chronyd* will accept these commands can be configured
+with the <<chrony.conf.adoc#cmdallow,*cmdallow*>> directive in the *chronyd*'s
+configuration file or the <<cmdallow,*cmdallow*>> command in *chronyc*. By
+default, the commands are accepted only from localhost (127.0.0.1 or ::1).
+
+All other commands are allowed only through the Unix domain socket. When sent
+over the network, *chronyd* will respond with a '`Not authorised`' error, even
+if it is from localhost.
+
+Having full access to *chronyd* via *chronyc* is more or less equivalent to
+being able to modify the *chronyd*'s configuration file and restart it.
+
+== OPTIONS
+
+*-4*::
+With this option hostnames will be resolved only to IPv4 addresses.
+
+*-6*::
+With this option hostnames will be resolved only to IPv6 addresses.
+
+*-n*::
+This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
+DNS lookups. Long addresses will not be truncated to fit into the column.
+
+*-N*::
+This option enables printing of original hostnames or IP addresses of NTP
+sources that were specified in the configuration file, or *chronyc* commands.
+Without the *-n* and *-N* option, the printed hostnames are obtained from
+reverse DNS lookups and can be different from the specified hostnames.
+
+*-c*::
+This option enables printing of reports in a comma-separated values (CSV)
+format. Reverse DNS lookups will be disabled, time will be printed as number of
+seconds since the epoch, and values in seconds will not be converted to other
+units.
+
+*-d*::
+This option enables printing of debugging messages if *chronyc* was compiled
+with debugging support.
+
+*-m*::
+Normally, all arguments on the command line are interpreted as one command.
+With this option multiple commands can be specified. Each argument will be
+interpreted as a whole command.
+
+*-h* _host_::
+This option specifies the host to be contacted by *chronyc*. It can be
+specified with a hostname, IP address, or path to the local Unix domain socket.
+Multiple values can be specified as a comma-separated list to provide a
+fallback.
++
+The default value is _@CHRONYRUNDIR@/chronyd.sock,127.0.0.1,::1_, i.e. the host
+where *chronyc* is being run. First, it tries to connect to the Unix domain
+socket and if that fails (e.g. due to running under a non-root user), it
+will try to connect to 127.0.0.1 and then ::1.
+
+*-p* _port_::
+This option allows the user to specify the UDP port number which the target
+*chronyd* is using for its monitoring connections. This defaults to 323; there
+would rarely be a need to change this.
+
+*-f* _file_::
+This option is ignored and is provided only for compatibility.
+
+*-a*::
+This option is ignored and is provided only for compatibility.
+
+*-v*, *--version*::
+With this option *chronyc* displays its version number on the terminal and
+exits.
+
+*--help*::
+With this option *chronyc* displays a help message on the terminal and
+exits.
+
+== COMMANDS
+
+This section describes each of the commands available within the *chronyc*
+program.
+
+=== System clock
+
+[[tracking]]*tracking*::
+The *tracking* command displays parameters about the system's clock
+performance. An example of the output is shown below.
++
+----
+Reference ID    : CB00710F (foo.example.net)
+Stratum         : 3
+Ref time (UTC)  : Fri Jan 27 09:49:17 2017
+System time     : 0.000006523 seconds slow of NTP time
+Last offset     : -0.000006747 seconds
+RMS offset      : 0.000035822 seconds
+Frequency       : 3.225 ppm slow
+Residual freq   : -0.000 ppm
+Skew            : 0.129 ppm
+Root delay      : 0.013639022 seconds
+Root dispersion : 0.001100737 seconds
+Update interval : 64.2 seconds
+Leap status     : Normal
+----
++
+The fields are explained as follows:
++
+*Reference ID*:::
+This is the reference ID and name (or IP address) of the server to which the
+computer is currently synchronised. For IPv4 addresses, the reference ID is
+equal to the address and for IPv6 addresses it is the first 32 bits of the MD5
+sum of the address.
++
+If the reference ID is _7F7F0101_ and there is no name or IP address, it means
+the computer is not synchronised to any external source and that you have the
+_local_ mode operating (via the <<local,*local*>> command in *chronyc*, or the
+<<chrony.conf.adoc#local,*local*>> directive in the configuration file).
++
+The reference ID is printed as a hexadecimal number. Note that in older
+versions it used to be printed in quad-dotted notation and could be confused
+with an IPv4 address.
+*Stratum*:::
+The stratum indicates how many hops away from a computer with an attached
+reference clock we are. Such a computer is a stratum-1 computer, so the
+computer in the example is two hops away (i.e. _foo.example.net_ is a
+stratum-2 and is synchronised from a stratum-1).
+*Ref time*:::
+This is the time (UTC) at which the last measurement from the reference
+source was processed.
+*System time*:::
+This is the current offset between the NTP clock and system clock. The NTP
+clock is a software (virtual) clock maintained by *chronyd*, which is
+synchronised to the configured time sources and provides time to NTP clients.
+The system clock is synchronised to the NTP clock. To avoid steps in the
+system time, which might have adverse consequences for certain applications,
+the system clock is normally corrected only by speeding up or slowing down (up
+to the rate configured by the <<chrony.conf.adoc#maxslewrate,*maxslewrate*>>
+directive). If the offset is too large, this correction will take a very long
+time. A step can be forced by the <<makestep,*makestep*>> command, or the
+<<chrony.conf.adoc#makestep,*makestep*>> directive in the configuration file.
++
+Note that all other offsets reported by *chronyc* and most offsets in the log
+files are relative to the NTP clock, not the system clock.
+*Last offset*:::
+This is the estimated local offset on the last clock update. A positive value
+indicates the local time (as previously estimated true time) was ahead of the
+time sources.
+*RMS offset*:::
+This is a long-term average of the offset value.
+*Frequency*:::
+The '`frequency`' is the rate by which the system's clock would be wrong if
+*chronyd* was not correcting it. It is expressed in ppm (parts per million).
+For example, a value of 1 ppm would mean that when the system's clock thinks it
+has advanced 1 second, it has actually advanced by 1.000001 seconds relative to
+true time.
+*Residual freq*:::
+This shows the '`residual frequency`' for the currently selected reference
+source. This reflects any difference between what the measurements from the
+reference source indicate the frequency should be and the frequency currently
+being used.
++
+The reason this is not always zero is that a smoothing procedure is
+applied to the frequency. Each time a measurement from the reference
+source is obtained and a new residual frequency computed, the estimated
+accuracy of this residual is compared with the estimated accuracy (see
+'`skew`' next) of the existing frequency value. A weighted average is
+computed for the new frequency, with weights depending on these accuracies.
+If the measurements from the reference source follow a consistent trend, the
+residual will be driven to zero over time.
+*Skew*:::
+This is the estimated error bound on the frequency.
+*Root delay*:::
+This is the total of the network path delays to the stratum-1 computer from
+which the computer is ultimately synchronised.
+*Root dispersion*:::
+This is the total dispersion accumulated through all the computers back to
+the stratum-1 computer from which the computer is ultimately synchronised.
+Dispersion is due to system clock resolution, statistical measurement
+variations, etc.
++
+An absolute bound on the computer's clock accuracy (assuming the stratum-1
+computer is correct) is given by:
++
+----
+clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay)
+----
+*Update interval*:::
+This is the interval between the last two clock updates.
+*Leap status*:::
+This is the leap status, which can be _Normal_, _Insert second_, _Delete
+second_ or _Not synchronised_.
+
+[[makestep]]*makestep*::
+*makestep* _threshold_ _limit_::
+Normally *chronyd* will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+the system clock might be so far adrift that this slewing process would take a
+very long time to correct the system clock.
++
+The *makestep* command can be used in this situation. There are two forms of
+the command. The first form has no parameters. It tells *chronyd* to cancel any
+remaining correction that was being slewed and jump the system clock by the
+equivalent amount, making it correct immediately.
++
+The second form configures the automatic stepping, similarly to the
+<<chrony.conf.adoc#makestep,*makestep*>> directive. It has two parameters,
+stepping threshold (in seconds) and number of future clock updates for which
+the threshold will be active. This can be used with the <<burst,*burst*>>
+command to quickly make a new measurement and correct the clock by stepping if
+needed, without waiting for *chronyd* to complete the measurement and update
+the clock.
++
+----
+makestep 0.1 1
+burst 1/2
+----
++
+BE WARNED: Certain software will be seriously affected by such jumps in the
+system time. (That is the reason why *chronyd* uses slewing normally.)
+
+[[maxupdateskew]]*maxupdateskew* _skew-in-ppm_::
+This command has the same effect as the
+<<chrony.conf.adoc#maxupdateskew,*maxupdateskew*>> directive in the
+configuration file.
+
+[[waitsync]]*waitsync* [_max-tries_ [_max-correction_ [_max-skew_ [_interval_]]]]::
+The *waitsync* command waits for *chronyd* to synchronise.
++
+Up to four optional arguments can be specified. The first is the maximum number
+of tries before giving up and returning a non-zero error code. When 0 is
+specified, or there are no arguments, the number of tries will not be limited.
++
+The second and third arguments are the maximum allowed remaining correction of
+the system clock and the maximum allowed skew (in ppm) as reported by the
+<<tracking,*tracking*>> command in the *System time* and *Skew* fields. If not
+specified or zero, the value will not be checked.
++
+The fourth argument is the interval specified in seconds in which the check is
+repeated. The interval is 10 seconds by default.
++
+An example is:
++
+----
+waitsync 60 0.01
+----
++
+which will wait up to about 10 minutes (60 times 10 seconds) for *chronyd* to
+synchronise to a source and the remaining correction to be less than 10
+milliseconds.
+
+=== Time sources
+
+[[sources]]*sources* [*-a*] [*-v*]::
+This command displays information about the current time sources that *chronyd*
+is accessing.
++
+If the *-a* option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+_ID#XXXXXXXXXX_, which can be used in other commands expecting a source address.
++
+The *-v* option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
++
+----
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+#* GPS0                          0   4   377    11   -479ns[ -621ns] +/-  134ns
+^? foo.example.net               2   6   377    23   -923us[ -924us] +/-   43ms
+^+ bar.example.net               1   6   377    21  -2629us[-2619us] +/-   86ms
+----
++
+The columns are as follows:
++
+*M*:::
+This indicates the mode of the source. _^_ means a server, _=_ means a peer
+and _#_ indicates a locally connected reference clock.
+*S*:::
+This column indicates the selection state of the source.
+* _*_ indicates the best source which is currently selected for
+  synchronisation.
+* _+_ indicates other sources selected for synchronisation, which are combined
+  with the best source.
+* _-_ indicates a source which is considered to be selectable for
+  synchronisation, but not currently selected.
+* _x_ indicates a source which *chronyd* thinks is a falseticker (i.e. its
+  time is inconsistent with a majority of other sources, or sources specified
+  with the *trust* option).
+* _~_ indicates a source whose time appears to have too much variability.
+* _?_ indicates a source which is not considered to be selectable for
+  synchronisation for other reasons (e.g. unreachable, not synchronised, or
+  does not have enough measurements).
+{blank}:::
+The <<selectdata,*selectdata*>> command can be used to get more details about
+the selection state.
+*Name/IP address*:::
+This shows the name or the IP address of the source, or reference ID for reference
+clocks.
+*Stratum*:::
+This shows the stratum of the source, as reported in its most recently
+received sample. Stratum 1 indicates a computer with a locally attached
+reference clock. A computer that is synchronised to a stratum 1 computer is
+at stratum 2. A computer that is synchronised to a stratum 2 computer is at
+stratum 3, and so on.
+*Poll*:::
+This shows the rate at which the source is being polled, as a base-2
+logarithm of the interval in seconds. Thus, a value of 6 would indicate that
+a measurement is being made every 64 seconds. *chronyd* automatically varies
+the polling rate in response to prevailing conditions.
+*Reach*:::
+This shows the source's reachability register printed as an octal number. The
+register has 8 bits and is updated on every received or missed packet from
+the source. A value of 377 indicates that a valid reply was received for all
+from the last eight transmissions.
+*LastRx*:::
+This column shows how long ago the last good sample (which is shown in the next
+column) was received from the source. Measurements that failed some tests are
+ignored. This is normally in seconds. The letters _m_, _h_, _d_ or _y_ indicate
+minutes, hours, days, or years.
+*Last sample*:::
+This column shows the offset between the local clock and the source at the
+last measurement. The number in the square brackets shows the actual measured
+offset. This can be suffixed by _ns_ (indicating nanoseconds), _us_
+(indicating microseconds), _ms_ (indicating milliseconds), or _s_ (indicating
+seconds). The number to the left of the square brackets shows the original
+measurement, adjusted to allow for any slews applied to the local clock
+since. The number following the _+/-_ indicator shows the margin of error in
+the measurement. Positive offsets indicate that the local clock is ahead of
+the source.
+
+[[sourcestats]]*sourcestats* [*-a*] [*-v*]::
+The *sourcestats* command displays information about the drift rate and offset
+estimation process for each of the sources currently being examined by
+*chronyd*.
++
+If the *-a* option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+_ID#XXXXXXXXXX_, which can be used in other commands expecting a source address.
++
+The *-v* option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
++
+An example report is:
++
+----
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+===============================================================================
+foo.example.net            11   5   46m     -0.001      0.045      1us    25us
+----
++
+The columns are as follows:
++
+*Name/IP Address*:::
+This is the name or IP address of the NTP server (or peer) or reference ID of the
+reference clock to which the rest of the line relates.
+*NP*:::
+This is the number of sample points currently being retained for the server.
+The drift rate and current offset are estimated by performing a linear
+regression through these points.
+*NR*:::
+This is the number of runs of residuals having the same sign following the
+last regression. If this number starts to become too small relative to the
+number of samples, it indicates that a straight line is no longer a good fit
+to the data. If the number of runs is too low, *chronyd* discards older
+samples and re-runs the regression until the number of runs becomes
+acceptable.
+*Span*:::
+This is the interval between the oldest and newest samples. If no unit is
+shown the value is in seconds. In the example, the interval is 46 minutes.
+*Frequency*:::
+This is the estimated residual frequency for the server, in parts per
+million. In this case, the computer's clock is estimated to be running 1 part
+in 10^9 slow relative to the server.
+*Freq Skew*:::
+This is the estimated error bounds on *Freq* (again in parts per million).
+*Offset*:::
+This is the estimated offset of the source.
+*Std Dev*:::
+This is the estimated sample standard deviation.
+
+[[selectdata]]*selectdata* [*-a*] [*-v*]::
+The *selectdata* command displays information specific to the selection of time
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. With the *-v* option, extra caption
+lines are shown as a reminder of the meanings of the columns.
++
+An example of the output is shown below.
++
+----
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+D foo.example.net           Y ----- --TR-    4   1.0   -61ms   +62ms  N
+* bar.example.net           N ----- -----    0   1.0 -6846us +7305us  N
++ baz.example.net           N ----- -----   10   1.0 -7381us +7355us  N
+----
++
+The columns are as follows:
++
+*S*:::
+This column indicates the state of the source after the last source selection.
+It is similar to the state reported by the *sources* command, but more
+states are reported.
+{blank}:::
+The following states indicate the source is not considered selectable for
+synchronisation:
+* _N_ - has the *noselect* option.
+* _s_ - is not synchronised.
+* _M_ - does not have enough measurements.
+* _d_ - has a root distance larger than the maximum distance (configured by the
+        <<chrony.conf.adoc#maxdistance,*maxdistance*>> directive).
+* _~_ - has a jitter larger than the maximum jitter (configured by the
+        <<chrony.conf.adoc#maxjitter,*maxjitter*>> directive).
+* _w_ - waits for other sources to get out of the _M_ state.
+* _S_ - has older measurements than other sources.
+* _O_ - has a stratum equal or larger than the orphan stratum (configured by
+        the <<chrony.conf.adoc#local,*local*>> directive).
+* _T_ - does not fully agree with sources that have the *trust* option.
+* _x_ - does not agree with other sources (falseticker).
+{blank}:::
+The following states indicate the source is considered selectable, but it is
+not currently used for synchronisation:
+* _W_ - waits for other sources to be selectable (required by the
+        <<chrony.conf.adoc#minsources,*minsources*>> directive, or
+        the *require* option of another source).
+* _P_ - another selectable source is preferred due to the *prefer* option.
+* _U_ - waits for a new measurement (after selecting a different best source).
+* _D_ - has, or recently had, a root distance which is too large to be combined
+        with other sources (configured by the
+        <<chrony.conf.adoc#combinelimit,*combinelimit*>> directive).
+{blank}:::
+The following states indicate the source is used for synchronisation of the
+local clock:
+* _+_ - combined with the best source.
+* _*_ - selected as the best source to update the reference data (e.g. root
+        delay, root dispersion).
+*Name/IP address*:::
+This column shows the name or IP address of the source if it is an NTP server,
+or the reference ID if it is a reference clock.
+*Auth*:::
+This column indicites whether an authentication mechanism is enabled for the
+source. _Y_ means yes and _N_ means no.
+*COpts*:::
+This column displays the configured selection options of the source.
+* _N_ indicates the *noselect* option.
+* _P_ indicates the *prefer* option.
+* _T_ indicates the *trust* option.
+* _R_ indicates the *require* option.
+*EOpts*:::
+This column displays the current effective selection options of the source,
+which can be different from the configured options due to the authentication
+selection mode (configured by the
+<<chrony.conf.adoc#authselmode,*authselmode*>> directive). The symbols are the
+same as in the *COpts* column.
+*Last*:::
+This column displays how long ago was the last measurement of the source made
+when the selection was performed.
+*Score*:::
+This column displays the current score against the source in the _*_ state. The
+scoring system avoids frequent reselection when multiple sources have a similar
+root distance. A value larger than 1 indicates this source was better than the
+_*_ source in recent selections. If the score reaches 10, the best source will
+be reselected and the scores will be reset to 1.
+*Interval*:::
+This column displays the lower and upper endpoint of the interval which was
+expected to contain the true offset of the local clock considering the root
+distance at the time of the selection.
+*Leap*:::
+This column displays the current leap status of the source.
+* _N_ indicates the normal status (no leap second).
+* _+_ indicates that a leap second will be inserted at the end of the month.
+* _-_ indicates that a leap second will be deleted at the end of the month.
+* _?_ indicates the unknown status (i.e. no valid measurement was made).
+
+[[reselect]]*reselect*::
+To avoid excessive switching between sources, *chronyd* can stay synchronised
+to a source even when it is not currently the best one among the available
+sources.
++
+The *reselect* command can be used to force *chronyd* to reselect the best
+synchronisation source.
+
+[[reselectdist]]*reselectdist* _distance_::
+The *reselectdist* command sets the reselection distance. It is equivalent to
+the <<chrony.conf.adoc#reselectdist,*reselectdist*>> directive in the
+configuration file.
+
+=== NTP sources
+
+[[activity]]*activity*::
+This command reports the number of servers and peers that are online and
+offline. If the *auto_offline* option is used in specifying some of the servers
+or peers, the *activity* command can be useful for detecting when all of them
+have entered the offline state after the network link has been disconnected.
++
+The report shows the number of servers and peers in 5 states:
++
+*online*:::
+the server or peer is currently online (i.e. assumed by *chronyd* to be reachable)
+*offline*:::
+the server or peer is currently offline (i.e. assumed by *chronyd* to be
+unreachable, and no measurements from it will be attempted.)
+*burst_online*:::
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the online state.
+*burst_offline*:::
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the offline state.
+*unresolved*:::
+the name of the server or peer was not resolved to an address yet; this source is
+not visible in the *sources* and *sourcestats* reports.
+
+[[authdata]]*authdata* [*-a*]::
+The *authdata* command displays information specific to authentication of NTP
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. An example of the output is
+shown below.
++
+----
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256 135m    0    0    8  100
+bar.example.net               SK    30   13  128    -    0    0    0    0
+baz.example.net                -     0    0    0    -    0    0    0    0
+----
++
+The columns are as follows:
++
+*Name/IP address*:::
+This column shows the name or the IP address of the source.
+*Mode*:::
+This column shows which mechanism authenticates NTP packets received from the
+source. _NTS_ means Network Time Security, _SK_ means a symmetric key, and _-_
+means authentication is disabled.
+*KeyID*:::
+This column shows an identifier of the key used for authentication. With a
+symmetric key, it is the ID from the <<chrony.conf.adoc#keyfile,key file>>.
+With NTS, it is a number starting at zero and incremented by one with each
+successful key establishment using the NTS-KE protocol, i.e. it shows how many
+times the key establishment was performed with this source.
+*Type*:::
+This columns shows an identifier of the algorithm used for authentication.
+With a symmetric key, it is the hash function or cipher specified in the key
+file. With NTS, it is an authenticated encryption with associated data (AEAD)
+algorithm, which is negotiated in the NTS-KE protocol. The following values can
+be reported:
+* 1: MD5
+* 2: SHA1
+* 3: SHA256
+* 4: SHA384
+* 5: SHA512
+* 6: SHA3-224
+* 7: SHA3-256
+* 8: SHA3-384
+* 9: SHA3-512
+* 10: TIGER
+* 11: WHIRLPOOL
+* 13: AES128
+* 14: AES256
+* 15: AEAD-AES-SIV-CMAC-256
+*KLen*:::
+This column shows the length of the key in bits.
+*Last*:::
+This column shows how long ago the last successful key establishment was
+performed. It is in seconds, or letters _m_, _h_, _d_ or _y_ indicate minutes,
+hours, days, or years.
+*Atmp*:::
+This column shows the number of attempts to perform the key establishment since
+the last successful key establishment. A number larger than 1 indicates a
+problem with the network or server.
+*NAK*:::
+This column shows whether an NTS NAK was received since the last request.
+A NAK indicates that authentication failed on the server side due to
+*chronyd* using a cookie which is no longer valid and that it needs to perform
+the key establishment again in order to get new cookies.
+*Cook*:::
+This column shows the number of NTS cookies that *chronyd* currently has. If
+the key establishment was successful, a number smaller than 8 indicates a
+problem with the network or server.
+*CLen*:::
+This column shows the length in bytes of the NTS cookie which will be used in
+the next request.
+
+[[ntpdata]]*ntpdata* [_address_]::
+The *ntpdata* command displays the last valid measurement and other
+NTP-specific information about the specified NTP source, or all NTP sources
+(with a known address) if no address was specified. An example of the output is
+shown below.
++
+----
+Remote address  : 203.0.113.15 (CB00710F)
+Remote port     : 123
+Local address   : 203.0.113.74 (CB00714A)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 10 (1024 seconds)
+Precision       : -24 (0.000000060 seconds)
+Root delay      : 0.000015 seconds
+Root dispersion : 0.000015 seconds
+Reference ID    : 47505300 (GPS)
+Reference time  : Fri Nov 25 15:22:12 2016
+Offset          : -0.000060878 seconds
+Peer delay      : 0.000175634 seconds
+Peer dispersion : 0.000000681 seconds
+Response time   : 0.000053050 seconds
+Jitter asymmetry: +0.00
+NTP tests       : 111 111 1111
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 24
+Total RX        : 24
+Total valid RX  : 24
+Total good RX   : 22
+----
++
+The fields are explained as follows:
++
+*Remote address*:::
+The IP address of the NTP server or peer, and the corresponding reference ID.
+*Remote port*:::
+The UDP port number to which the request was sent. The standard NTP port is
+123.
+*Local address*:::
+The local IP address which received the response, and the corresponding
+reference ID.
+*Leap status*:::
+*Version*:::
+*Mode*:::
+*Stratum*:::
+*Poll interval*:::
+*Precision*:::
+*Root delay*:::
+*Root dispersion*:::
+*Reference ID*:::
+*Reference time*:::
+The NTP values from the last valid response.
+*Offset*:::
+*Peer delay*:::
+*Peer dispersion*:::
+The measured values.
+*Response time*:::
+The time the server or peer spent in processing of the request and waiting
+before sending the response.
+*Jitter asymmetry*:::
+The estimated asymmetry of network jitter on the path to the source. The
+asymmetry can be between -0.5 and 0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent
+from the source back.
+*NTP tests*:::
+Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum
+delay, delay ratio, delay dev ratio (or delay quantile), and synchronisation
+loop.
+*Interleaved*:::
+This shows if the response was in the interleaved mode.
+*Authenticated*:::
+This shows if the response was authenticated.
+*TX timestamping*:::
+The source of the local transmit timestamp. Valid values are _Daemon_,
+_Kernel_, and _Hardware_.
+*RX timestamping*:::
+The source of the local receive timestamp.
+*Total TX*:::
+The number of packets sent to the source.
+*Total RX*:::
+The number of all packets received from the source.
+*Total valid RX*:::
+The number of packets which passed the first two groups of NTP tests.
+*Total good RX*:::
+The number of packets which passed all three groups of NTP tests, i.e. the NTP
+measurement was accepted.
+
+[[add_peer]]*add peer* _name_ [_option_]...::
+The *add peer* command allows a new NTP peer to be added whilst
+*chronyd* is running.
++
+Following the words *add peer*, the syntax of the following
+parameters and options is identical to that for the
+<<chrony.conf.adoc#peer,*peer*>> directive in the configuration file.
++
+An example of using this command is shown below.
++
+----
+add peer foo.example.net minpoll 6 maxpoll 10 key 25
+----
+
+[[add_pool]]*add pool* _name_ [_option_]...::
+The *add pool* command allows a pool of NTP servers to be added whilst
+*chronyd* is running.
++
+Following the words *add pool*, the syntax of the following parameters and
+options is identical to that for the <<chrony.conf.adoc#pool,*pool*>>
+directive in the configuration file.
++
+An example of using this command is shown below:
++
+----
+add pool foo.example.net maxsources 3 iburst
+----
+
+[[add_server]]*add server* _name_ [_option_]...::
+The *add server* command allows a new NTP server to be added whilst
+*chronyd* is running.
++
+Following the words *add server*, the syntax of the following parameters and
+options is identical to that for the <<chrony.conf.adoc#server,*server*>>
+directive in the configuration file.
++
+An example of using this command is shown below:
++
+----
+add server foo.example.net minpoll 6 maxpoll 10 key 25
+----
+
+[[delete]]*delete* _address_::
+The *delete* command allows an NTP server or peer to be removed
+from the current set of sources.
+
+[[burst]]
+*burst* _good_/_max_ [_mask_/_masked-address_]::
+*burst* _good_/_max_ [_masked-address_/_masked-bits_]::
+*burst* _good_/_max_ [_address_]::
+The *burst* command tells *chronyd* to make a set of measurements to each of
+its NTP sources over a short duration (rather than the usual periodic
+measurements that it makes). After such a burst, *chronyd* will revert to the
+previous state for each source. This might be either online, if the source was
+being periodically measured in the normal way, or offline, if the source had
+been indicated as being offline. (A source can be switched between the online
+and offline states with the <<online,*online*>> and <<offline,*offline*>>
+commands.)
++
+The _mask_ and _masked-address_ arguments are optional, in which case *chronyd*
+will initiate a burst for all of its currently defined sources.
++
+The arguments have the following meaning and format:
++
+_good_:::
+This defines the number of good measurements that *chronyd* will want to
+obtain from each source. A measurement is good if it passes certain tests,
+for example, the round trip time to the source must be acceptable. (This
+allows *chronyd* to reject measurements that are likely to be bogus.)
+_max_:::
+This defines the maximum number of measurements that *chronyd* will attempt
+to make, even if the required number of good measurements has not been
+obtained.
+_mask_:::
+This is an IP address with which the IP address of each of *chronyd*'s
+sources is to be masked.
+_masked-address_:::
+This is an IP address. If the masked IP address of a source matches this
+value then the burst command is applied to that source.
+_masked-bits_:::
+This can be used with _masked-address_ for CIDR notation, which is a shorter
+alternative to the form with mask.
+_address_:::
+This is an IP address or a hostname. The burst command is applied only to
+that source.
+{blank}::
++
+If no _mask_ or _masked-address_ arguments are provided, every source will be
+matched.
++
+An example of the two-argument form of the command is:
++
+----
+burst 2/10
+----
++
+This will cause *chronyd* to attempt to get two good measurements from each
+source, stopping after two have been obtained, but in no event will it try more
+than ten probes to the source.
++
+Examples of the four-argument form of the command are:
++
+----
+burst 2/10 255.255.0.0/1.2.0.0
+burst 2/10 2001:db8:789a::/48
+----
++
+In the first case, the two out of ten sampling will only be applied to sources
+whose IPv4 addresses are of the form _1.2.x.y_, where _x_ and _y_ are
+arbitrary. In the second case, the sampling will be applied to sources whose
+IPv6 addresses have first 48 bits equal to _2001:db8:789a_.
++
+Example of the three-argument form of the command is:
++
+----
+burst 2/10 foo.example.net
+----
+
+[[maxdelay]]*maxdelay* _address_ _delay_::
+This allows the *maxdelay* option for one of the sources to be modified, in the
+same way as specifying the *maxdelay* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxdelaydevratio]]*maxdelaydevratio* _address_ _ratio_::
+This allows the *maxdelaydevratio* option for one of the sources to be
+modified, in the same way as specifying the *maxdelaydevratio* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxdelayratio]]*maxdelayratio* _address_ _ratio_::
+This allows the *maxdelayratio* option for one of the sources to be modified,
+in the same way as specifying the *maxdelayratio* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxpoll]]*maxpoll* _address_ _maxpoll_::
+The *maxpoll* command is used to modify the maximum polling interval for one of
+the current set of sources. It is equivalent to the *maxpoll* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
++
+Note that the new maximum polling interval only takes effect after the next
+measurement has been made.
+
+[[minpoll]]*minpoll* _address_ _minpoll_::
+The *minpoll* command is used to modify the minimum polling interval for one of
+the current set of sources. It is equivalent to the *minpoll* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
++
+Note that the new minimum polling interval only takes effect after the next
+measurement has been made.
+
+[[minstratum]]*minstratum* _address_ _minstratum_::
+The *minstratum* command is used to modify the minimum stratum for one of the
+current set of sources. It is equivalent to the *minstratum* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[offline]]
+*offline* [_address_]::
+*offline* [_masked-address_/_masked-bits_]::
+*offline* [_mask_/_masked-address_]::
+The *offline* command is used to warn *chronyd* that the network connection to
+a particular host or hosts is about to be lost, e.g. on computers with
+intermittent connection to their time sources.
++
+Another case where *offline* could be used is where a computer serves time to a
+local group of computers, and has a permanent connection to true time servers
+outside the organisation. However, the external connection is heavily loaded at
+certain times of the day and the measurements obtained are less reliable at
+those times. In this case, it is probably most useful to determine the
+gain or loss rate during the quiet periods and let the whole network coast through
+the loaded periods. The *offline* and *online* commands can be used to achieve
+this.
++
+There are four forms of the *offline* command. The first form is a wildcard,
+meaning all sources (including sources that do not have a known address yet).
+The second form allows an IP address mask and a masked
+address to be specified. The third form uses CIDR notation. The fourth form
+uses an IP address or a hostname. These forms are illustrated below.
++
+----
+offline
+offline 255.255.255.0/1.2.3.0
+offline 2001:db8:789a::/48
+offline foo.example.net
+----
++
+The second form means that the *offline* command is to be applied to any source
+whose IPv4 address is in the _1.2.3_ subnet. (The host's address is logically
+and-ed with the mask, and if the result matches the _masked-address_ the host
+is processed.) The third form means that the command is to be applied to all
+sources whose IPv6 addresses have their first 48 bits equal to _2001:db8:789a_. The
+fourth form means that the command is to be applied only to that one source.
++
+The wildcard form of the address is equivalent to:
++
+----
+offline 0.0.0.0/0.0.0.0
+offline ::/0
+----
+
+[[online]]
+*online* [_address_]::
+*online* [_masked-address_/_masked-bits_]::
+*online* [_mask_/_masked-address_]::
+The *online* command is opposite in function to the <<offline,*offline*>>
+command. It is used to advise *chronyd* that network connectivity to a
+particular source or sources has been restored.
++
+The syntax is identical to that of the <<offline,*offline*>> command.
+
+[[onoffline]]
+*onoffline*::
+The *onoffline* command tells *chronyd* to switch all sources that have a known
+address to the online or
+offline status according to the current network configuration. A source is
+considered online if it is possible to send requests to it, i.e. a network
+route to the source is present.
+
+[[polltarget]]*polltarget* _address_ _polltarget_::
+The *polltarget* command is used to modify the poll target for one of the
+current set of sources. It is equivalent to the *polltarget* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[refresh]]*refresh*::
+The *refresh* command can be used to force *chronyd* to resolve the names of
+configured sources to IP addresses again, e.g. after suspending and resuming
+the machine in a different network.
++
+Sources that stop responding will be replaced with newly resolved addresses
+automatically after 8 polling intervals, but this command can still be useful
+to replace them immediately and not wait until they are marked as unreachable.
+
+[[reload]]*reload* *sources*::
+The *reload sources* command causes *chronyd* to re-read all _*.sources_ files
+from the directories specified by the
+<<chrony.conf.adoc#sourcedir,*sourcedir*>> directive.
+
+[[sourcename]]*sourcename* _address_::
+The *sourcename* command prints the original hostname or address that was
+specified for an NTP source in the configuration file, or the *add* command.
+This command is an alternative to the *-N* option, which can be useful in
+scripts.
++
+Note that different NTP sources can share the same name, e.g. servers from a
+pool.
+
+=== Manual time input
+
+[[manual]]
+*manual* *on*::
+*manual* *off*::
+*manual* *delete* _index_::
+*manual* *list*::
+*manual* *reset*::
+The manual command enables and disables use of the <<settime,*settime*>>
+command, and is used to modify the behaviour of the manual clock driver.
++
+The *on* form of the command enables use of the *settime* command.
++
+The *off* form of the command disables use of the *settime* command.
++
+The *list* form of the command lists all the samples currently stored in
+*chronyd*. The output is illustrated below.
++
+----
+210 n_samples = 1
+#    Date  Time(UTC)    Slewed   Original   Residual
+====================================================
+ 0 27Jan99 22:09:20       0.00       0.97       0.00
+----
++
+The columns are as as follows:
++
+. The sample index (used for the *manual delete* command).
+. The date and time of the sample.
+. The system clock error when the timestamp was entered, adjusted to allow
+  for changes made to the system clock since.
+. The system clock error when the timestamp was entered, as it originally was
+  (without allowing for changes to the system clock since).
+. The regression residual at this point, in seconds. This allows '`outliers`'
+  to be easily spotted, so that they can be deleted using the *manual delete*
+  command.
+{blank}::
++
+The *delete* form of the command deletes a single sample. The parameter is the
+index of the sample, as shown in the first column of the output from *manual
+list*. Following deletion of the data point, the current error and drift rate
+are re-estimated from the remaining data points and the system clock trimmed if
+necessary. This option is intended to allow '`outliers`' to be discarded, i.e.
+samples where the administrator realises they have entered a very poor
+timestamp.
++
+The *reset* form of the command deletes all samples at once. The system clock
+is left running as it was before the command was entered.
+
+[[settime]]*settime* _time_::
+The *settime* command allows the current time to be entered manually, if this
+option has been configured into *chronyd*. (It can be configured either with
+the <<chrony.conf.adoc#manual,*manual*>> directive in the configuration file,
+or with the <<manual,*manual*>> command of *chronyc*.)
++
+It should be noted that the computer's sense of time will only be as accurate
+as the reference you use for providing this input (e.g. your watch), as well as
+how well you can time the press of the return key.
++
+Providing your computer's time zone is set up properly, you will be able to
+enter a local time (rather than UTC).
++
+The response to a successful *settime* command indicates the amount that the
+computer's clock was wrong. It should be apparent from this if you have entered
+the time wrongly, e.g. with the wrong time zone.
++
+The rate of drift of the system clock is estimated by a regression process
+using the entered measurement and all previous measurements entered during the
+present run of *chronyd*. However, the entered measurement is used for
+adjusting the current clock offset (rather than the estimated intercept from
+the regression, which is ignored). Contrast what happens with the
+<<manual,*manual delete*>> command, where the intercept is used to set the
+current offset (since there is no measurement that has just been entered in
+that case).
++
+The time is parsed by the public domain _getdate_ algorithm. Consequently, you
+can only specify time to the nearest second.
++
+Examples of inputs that are valid are shown below:
++
+----
+settime 16:30
+settime 16:30:05
+settime Nov 21, 2015 16:30:05
+----
++
+For a full description of getdate, see the getdate documentation
+(bundled, for example, with the source for GNU tar).
+
+=== NTP access
+
+[[accheck]]*accheck* _address_::
+This command allows you to check whether client NTP access is allowed from a
+particular host.
++
+Examples of use, showing a named host and a numeric IP address, are as follows:
++
+----
+accheck foo.example.net
+accheck 1.2.3.4
+accheck 2001:db8::1
+----
++
+This command can be used to examine the effect of a series of *allow*, *allow
+all*, *deny*, and *deny all* commands specified either via *chronyc*, or in
+*chronyd*'s configuration file.
+
+[[clients]]*clients* [*-p* _packets_] [*-k*] [*-r*]::
+This command shows a list of clients that have accessed the server, through
+the NTP, command, or NTS-KE port. It does not include accesses over the Unix
+domain command socket.
++
+The *-p* option specifies the minimum number of received NTP or command
+packets, or accepted NTS-KE connections, needed to include a client in the
+list. The default value is 0, i.e. all clients are reported. With the *-k*
+option the last four columns will show the NTS-KE accesses instead of command
+accesses. If the *-r* option is specified, *chronyd* will reset the counters of
+received and dropped packets or connections after reporting the current values.
++
+An example of the output is:
++
+----
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+localhost                       2      0   2   -   133      15      0  -1     7
+foo.example.net                12      0   6   -    23       0      0   -     -
+----
++
+Each row shows the data for a single host. Only hosts that have passed the host
+access checks (set with the <<allow,*allow*>>, <<deny,*deny*>>,
+<<cmdallow,*cmdallow*>> and <<cmddeny,*cmddeny*>> commands or configuration
+file directives) are logged. The intervals are displayed as a power of 2 in
+seconds.
++
+The columns are as follows:
++
+. The hostname of the client.
+. The number of NTP packets received from the client.
+. The number of NTP packets dropped to limit the response rate.
+. The average interval between NTP packets.
+. The average interval between NTP packets after limiting the response rate.
+. Time since the last NTP packet was received
+. The number of command packets or NTS-KE connections received/accepted from
+  the client.
+. The number of command packets or NTS-KE connections dropped to limit the
+  response rate.
+. The average interval between command packets or NTS-KE connections.
+. Time since the last command packet or NTS-KE connection was
+  received/accepted.
+
+[[serverstats]]*serverstats*::
+The *serverstats* command displays NTP and command server statistics.
++
+An example of the output is shown below.
++
+----
+NTP packets received       : 1598
+NTP packets dropped        : 8
+Command packets received   : 19
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 3
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 189
+Interleaved NTP packets    : 43
+NTP timestamps held        : 44
+NTP timestamp span         : 120
+----
++
+The fields have the following meaning:
++
+*NTP packets received*:::
+The number of valid NTP requests received by the server.
+*NTP packets dropped*:::
+The number of NTP requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ratelimit,*ratelimit*>> directive).
+*Command packets received*:::
+The number of command requests received by the server.
+*Command packets dropped*:::
+The number of command requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#cmdratelimit,*cmdratelimit*>> directive).
+*Client log records dropped*:::
+The number of client log records dropped by the server to limit the memory use
+(configured by the <<chrony.conf.adoc#clientloglimit,*clientloglimit*>>
+directive).
+*NTS-KE connections accepted*:::
+The number of NTS-KE connections accepted by the server.
+*NTS-KE connections dropped*:::
+The number of NTS-KE connections dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ntsratelimit,*ntsratelimit*>> directive).
+*Authenticated NTP packets*:::
+The number of received NTP requests that were authenticated (with a symmetric
+key or NTS).
+*Interleaved NTP packets*:::
+The number of received NTP requests that were detected to be in the interleaved
+mode.
+*NTP timestamps held*:::
+The number of pairs of receive and transmit timestamps that the server is
+currently holding in memory for clients using the interleaved mode.
+*NTP timestamp span*:::
+The interval (in seconds) covered by the currently held NTP timestamps.
+{blank}::
++
+Note that the numbers reported by this overflow to zero after 4294967295
+(32-bit values).
+
+[[allow]]*allow* [*all*] [_subnet_]::
+The effect of the allow command is identical to the
+<<chrony.conf.adoc#allow,*allow*>> directive in the configuration file.
++
+The syntax is illustrated in the following examples:
++
+----
+allow 1.2.3.4
+allow all 3.4.5.0/24
+allow 2001:db8:789a::/48
+allow 0/0
+allow ::/0
+allow
+allow all
+----
+
+[[deny]]*deny* [*all*] [_subnet_]::
+The effect of the allow command is identical to the
+<<chrony.conf.adoc#deny,*deny*>> directive in the configuration file.
++
+The syntax is illustrated in the following examples:
++
+----
+deny 1.2.3.4
+deny all 3.4.5.0/24
+deny 2001:db8:789a::/48
+deny 0/0
+deny ::/0
+deny
+deny all
+----
+
+[[local]]
+*local* [_option_]...::
+*local* *off*::
+The *local* command allows *chronyd* to be told that it is to appear as a
+reference source, even if it is not itself properly synchronised to an external
+source. (This can be used on isolated networks, to allow one computer to be a
+master time server with the other computers slaving to it.)
++
+The first form enables the local reference mode on the host. The syntax is
+identical to the <<chrony.conf.adoc#local,*local*>> directive in the
+configuration file.
++
+The second form disables the local reference mode.
+
+[[smoothing]]*smoothing*::
+The *smoothing* command displays the current state of the NTP server time
+smoothing, which can be enabled with the
+<<chrony.conf.adoc#smoothtime,*smoothtime*>> directive. An example of the
+output is shown below.
++
+----
+Active         : Yes
+Offset         : +1.000268817 seconds
+Frequency      : -0.142859 ppm
+Wander         : -0.010000 ppm per second
+Last update    : 17.8 seconds ago
+Remaining time : 19988.4 seconds
+----
++
+The fields are explained as follows:
++
+*Active*:::
+This shows if the server time smoothing is currently active. Possible values
+are _Yes_ and _No_. If the *leaponly* option is included in the *smoothtime*
+directive, _(leap second only)_ will be shown on the line.
+*Offset*:::
+This is the current offset applied to the time sent to NTP clients. Positive
+value means the clients are getting time that's ahead of true time.
+*Frequency*:::
+The current frequency offset of the served time. Negative value means the
+time observed by clients is running slower than true time.
+*Wander*:::
+The current frequency wander of the served time. Negative value means the
+time observed by clients is slowing down.
+*Last update*:::
+This field shows how long ago the time smoothing process was updated, e.g.
+*chronyd* accumulated a new measurement.
+*Remaining time*:::
+The time it would take for the smoothing process to get to zero offset and
+frequency if there were no more updates.
+
+[[smoothtime]]
+*smoothtime* *activate*::
+*smoothtime* *reset*::
+The *smoothtime* command can be used to activate or reset the server time
+smoothing process if it is configured with the
+<<chrony.conf.adoc#smoothtime,*smoothtime*>> directive.
+
+=== Monitoring access
+
+[[cmdaccheck]]*cmdaccheck* _address_::
+This command is similar to the <<accheck,*accheck*>> command, except that it is
+used to check whether monitoring access is permitted from a named host.
++
+Examples of use are as follows:
++
+----
+cmdaccheck foo.example.net
+cmdaccheck 1.2.3.4
+cmdaccheck 2001:db8::1
+----
+
+[[cmdallow]]*cmdallow* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> command, except that it is used to
+allow particular hosts or subnets to use *chronyc* to monitor with *chronyd* on
+the current host.
+
+[[cmddeny]]*cmddeny* [*all*] [_subnet_]::
+This is similar to the <<deny,*deny*>> command, except that it is used to allow
+particular hosts or subnets to use *chronyc* to monitor *chronyd* on the
+current host.
+
+=== Real-time clock (RTC)
+
+[[rtcdata]]*rtcdata*::
+The *rtcdata* command displays the current RTC parameters.
++
+An example output is shown below.
++
+----
+RTC ref time (GMT) : Sat May 30 07:25:56 2015
+Number of samples  : 10
+Number of runs     : 5
+Sample span period :  549
+RTC is fast by     :    -1.632736 seconds
+RTC gains time at  :  -107.623 ppm
+----
++
+The fields have the following meaning:
++
+*RTC ref time (GMT)*:::
+This is the RTC reading the last time its error was measured.
+*Number of samples*:::
+This is the number of previous measurements being used to determine the RTC
+gain or loss rate.
+*Number of runs*:::
+This is the number of runs of residuals of the same sign following the
+regression fit for (RTC error) versus (RTC time). A value which is small
+indicates that the measurements are not well approximated by a linear model,
+and that the algorithm will tend to delete the older measurements to improve
+the fit.
+*Sample span period*:::
+This is the period that the measurements span (from the oldest to the
+newest). Without a unit the value is in seconds; suffixes _m_ for minutes,
+_h_ for hours, _d_ for days or _y_ for years can be used.
+*RTC is fast by*:::
+This is the estimate of how many seconds fast the RTC when it thought
+the time was at the reference time (above). If this value is large, you
+might (or might not) want to use the <<trimrtc,*trimrtc*>> command to bring the
+RTC into line with the system clock. (Note, a large error will not affect
+*chronyd*'s operation, unless it becomes so big as to start causing rounding
+errors.)
+*RTC gains time at*:::
+This is the amount of time gained (positive) or lost (negative) by the real
+time clock for each second that it ticks. It is measured in parts per
+million. So if the value shown was +1, suppose the RTC was exactly right when
+it crosses a particular second boundary. Then it would be 1 microsecond fast
+when it crosses its next second boundary.
+
+[[trimrtc]]*trimrtc*::
+The *trimrtc* command is used to correct the system's real-time clock (RTC) to
+the main system clock. It has no effect if the error between the two clocks is
+currently estimated at less than a second.
++
+The command takes no arguments. It performs the following steps (if the RTC is
+more than 1 second away from the system clock):
++
+. Remember the currently estimated gain or loss rate of the RTC and flush the
+  previous measurements.
+. Step the real-time clock to bring it within a second of the system clock.
+. Make several measurements to accurately determine the new offset between
+  the RTC and the system clock (i.e. the remaining fraction of a second
+  error).
+. Save the RTC parameters to the RTC file (specified with the
+  <<chrony.conf.adoc#rtcfile,*rtcfile*>> directive in the configuration file).
+{blank}::
++
+The last step is done as a precaution against the computer suffering a power
+failure before either the daemon exits or the <<writertc,*writertc*>> command
+is issued.
++
+*chronyd* will still work perfectly well both whilst operating and across
+machine reboots even if the *trimrtc* command is never used (and the RTC is
+allowed to drift away from true time). The *trimrtc* command is provided as a
+method by which it can be corrected, in a manner compatible with *chronyd*
+using it to maintain accurate time across machine reboots.
++
+The *trimrtc* command can be executed automatically by *chronyd* with the
+<<chrony.conf.adoc#rtcautotrim,*rtcautotrim*>> directive in the configuration
+file.
+
+[[writertc]]*writertc*::
+The *writertc* command writes the currently estimated error and gain or loss rate
+parameters for the RTC to the RTC file (specified with the
+<<chrony.conf.adoc#rtcfile,*rtcfile*>> directive). This information is also
+written automatically when *chronyd* is killed (by the SIGHUP, SIGINT, SIGQUIT
+or SIGTERM signals) or when the <<trimrtc,*trimrtc*>> command is issued.
+
+=== Other daemon commands
+
+[[cyclelogs]]*cyclelogs*::
+The *cyclelogs* command causes all of *chronyd*'s open log files to be closed
+and re-opened. This allows them to be renamed so that they can be periodically
+purged. An example of how to do this is shown below.
++
+----
+# mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
+# chronyc cyclelogs
+# rm /var/log/chrony/measurements1.log
+----
+
+[[dump]]*dump*::
+The *dump* command causes *chronyd* to write its current history of
+measurements for each of its sources to dump files in the directory specified
+in the configuration file by the <<chrony.conf.adoc#dumpdir,*dumpdir*>>
+directive and also write server NTS keys and client NTS cookies to the
+directory specified by the <<chrony.conf.adoc#ntsdumpdir1,*ntsdumpdir*>>
+directive. Note that *chronyd* does this automatically when it exits. This
+command is mainly useful for inspection whilst *chronyd* is running.
+
+[[rekey]]*rekey*::
+The *rekey* command causes *chronyd* to re-read the key file specified in the
+configuration file by the <<chrony.conf.adoc#keyfile,*keyfile*>> directive. It
+also re-reads the server NTS keys if
+<<chrony.conf.adoc#ntsdumpdir2,*ntsdumpdir*>> is specified and
+<<chrony.conf.adoc#ntsrotate,automatic rotation>> is disabled in the
+configuration file.
+
+[[reset]]*reset* *sources*::
+The *reset sources* command causes *chronyd* to drop all measurements and
+switch to the unsynchronised state. This command can help *chronyd* with
+recovery when the measurements are known to be no longer valid or accurate,
+e.g. due to moving the computer to a different network, or resuming the
+computer from a low-power state (which resets the system clock). *chronyd* will
+drop the measurements automatically when it detects the clock has made an
+unexpected jump, but the detection is not completely reliable.
+
+[[shutdown]]*shutdown*::
+The *shutdown* command causes *chronyd* to exit. This is equivalent to sending
+the process the SIGTERM signal.
+
+=== Client commands
+
+[[dns]]*dns* _option_::
+The *dns* command configures how hostnames and IP addresses are resolved in
+*chronyc*. IP addresses can be resolved to hostnames when printing results of
+<<sources,*sources*>>, <<sourcestats,*sourcestats*>>, <<tracking,*tracking*>>
+and <<clients,*clients*>> commands. Hostnames are resolved in commands that
+take an address as argument.
++
+There are five options:
++
+*dns -n*:::
+Disables resolving IP addresses to hostnames. Raw IP addresses will be
+displayed.
+*dns +n*:::
+Enables resolving IP addresses to hostnames. This is the default unless
+*chronyc* was started with *-n* option.
+*dns -4*:::
+Resolves hostnames only to IPv4 addresses.
+*dns -6*:::
+Resolves hostnames only to IPv6 addresses.
+*dns -46*:::
+Resolves hostnames to both address families. This is the default behaviour
+unless *chronyc* was started with the *-4* or *-6* option.
+
+[[timeout]]*timeout* _timeout_::
+The *timeout* command sets the initial timeout for *chronyc* requests in
+milliseconds. If no response is received from *chronyd*, the timeout is doubled
+and the request is resent. The maximum number of retries is configured with the
+<<retries,*retries*>> command.
++
+By default, the timeout is 1000 milliseconds.
+
+[[retries]]*retries* _retries_::
+The *retries* command sets the maximum number of retries for *chronyc* requests
+before giving up. The response timeout is controlled by the
+<<timeout,*timeout*>> command.
++
+The default is 2.
+
+[[keygen]]*keygen* [_id_ [_type_ [_bits_]]]::
+The *keygen* command generates a key that can be added to the
+key file (specified with the <<chrony.conf.adoc#keyfile,*keyfile*>> directive)
+to allow NTP authentication between server and client, or peers. The key is
+generated from the _/dev/urandom_ device and it is printed to standard output.
++
+The command has three optional arguments. The first argument is the key number
+(by default 1), which will be specified with the *key* option of the *server*
+or *peer* directives in the configuration file. The second argument is the name
+of the hash function or cipher (by default SHA1, or MD5 if SHA1 is not
+available). The third argument is the length of the key in bits if a hash
+function was selected, between 80 and 4096 bits (by default 160 bits).
++
+An example is:
++
+----
+keygen 73 SHA1 256
+----
++
+which generates a 256-bit SHA1 key with number 73. The printed line should
+then be securely transferred and added to the key files on both server and
+client, or peers. A different key should be generated for each client or peer.
++
+An example using the AES128 cipher is:
++
+----
+keygen 151 AES128
+----
+
+[[exit]]*exit*::
+[[quit]]*quit*::
+The *exit* and *quit* commands exit from *chronyc* and return the user to the shell.
+
+[[help]]*help*::
+The *help* command displays a summary of the commands and their arguments.
+
+== SEE ALSO
+
+<<chrony.conf.adoc#,*chrony.conf(5)*>>, <<chronyd.adoc#,*chronyd(8)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony.tuxfamily.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chronyc.man.in b/doc/chronyc.man.in
new file mode 100644
index 0000000..36b5c81
--- /dev/null
+++ b/doc/chronyc.man.in
@@ -0,0 +1,2672 @@
+'\" t
+.\"     Title: chronyc
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.15
+.\"      Date: 2022-08-29
+.\"    Manual: User manual
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONYC" "1" "2022-08-29" "chrony @CHRONY_VERSION@" "User manual"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chronyc \- command\-line interface for chrony daemon
+.SH "SYNOPSIS"
+.sp
+\fBchronyc\fP [\fIOPTION\fP]... [\fICOMMAND\fP]...
+.SH "DESCRIPTION"
+.sp
+\fBchronyc\fP is a command\-line interface program which can be used to monitor
+\fBchronyd\fP\(aqs performance and to change various operating parameters whilst it is
+running.
+.sp
+If no commands are specified on the command line, \fBchronyc\fP will expect input
+from the user. The prompt \fIchronyc>\fP will be displayed when it is being run
+from a terminal. If \fBchronyc\fP\(aqs input or output are redirected from or to a file,
+the prompt will not be shown.
+.sp
+There are two ways \fBchronyc\fP can access \fBchronyd\fP. One is the Internet
+Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is
+accessible locally by the root or \fIchrony\fP user. By default, \fBchronyc\fP first
+tries to connect to the Unix domain socket. The compiled\-in default path is
+\fI@CHRONYRUNDIR@/chronyd.sock\fP. If that fails (e.g. because \fBchronyc\fP is
+running under a non\-root user), it will try to connect to 127.0.0.1 and then
+::1.
+.sp
+Only the following monitoring commands, which do not affect the behaviour of
+\fBchronyd\fP, are allowed from the network: \fBactivity\fP, \fBmanual list\fP,
+\fBrtcdata\fP, \fBsmoothing\fP, \fBsourcename\fP, \fBsources\fP, \fBsourcestats\fP, \fBtracking\fP,
+\fBwaitsync\fP. The
+set of hosts from which \fBchronyd\fP will accept these commands can be configured
+with the \fBcmdallow\fP directive in the \fBchronyd\fP\(aqs
+configuration file or the \fBcmdallow\fP command in \fBchronyc\fP. By
+default, the commands are accepted only from localhost (127.0.0.1 or ::1).
+.sp
+All other commands are allowed only through the Unix domain socket. When sent
+over the network, \fBchronyd\fP will respond with a \(oqNot authorised\(cq error, even
+if it is from localhost.
+.sp
+Having full access to \fBchronyd\fP via \fBchronyc\fP is more or less equivalent to
+being able to modify the \fBchronyd\fP\(aqs configuration file and restart it.
+.SH "OPTIONS"
+.sp
+\fB\-4\fP
+.RS 4
+With this option hostnames will be resolved only to IPv4 addresses.
+.RE
+.sp
+\fB\-6\fP
+.RS 4
+With this option hostnames will be resolved only to IPv6 addresses.
+.RE
+.sp
+\fB\-n\fP
+.RS 4
+This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
+DNS lookups. Long addresses will not be truncated to fit into the column.
+.RE
+.sp
+\fB\-N\fP
+.RS 4
+This option enables printing of original hostnames or IP addresses of NTP
+sources that were specified in the configuration file, or \fBchronyc\fP commands.
+Without the \fB\-n\fP and \fB\-N\fP option, the printed hostnames are obtained from
+reverse DNS lookups and can be different from the specified hostnames.
+.RE
+.sp
+\fB\-c\fP
+.RS 4
+This option enables printing of reports in a comma\-separated values (CSV)
+format. Reverse DNS lookups will be disabled, time will be printed as number of
+seconds since the epoch, and values in seconds will not be converted to other
+units.
+.RE
+.sp
+\fB\-d\fP
+.RS 4
+This option enables printing of debugging messages if \fBchronyc\fP was compiled
+with debugging support.
+.RE
+.sp
+\fB\-m\fP
+.RS 4
+Normally, all arguments on the command line are interpreted as one command.
+With this option multiple commands can be specified. Each argument will be
+interpreted as a whole command.
+.RE
+.sp
+\fB\-h\fP \fIhost\fP
+.RS 4
+This option specifies the host to be contacted by \fBchronyc\fP. It can be
+specified with a hostname, IP address, or path to the local Unix domain socket.
+Multiple values can be specified as a comma\-separated list to provide a
+fallback.
+.sp
+The default value is \fI@CHRONYRUNDIR@/chronyd.sock,127.0.0.1,::1\fP, i.e. the host
+where \fBchronyc\fP is being run. First, it tries to connect to the Unix domain
+socket and if that fails (e.g. due to running under a non\-root user), it
+will try to connect to 127.0.0.1 and then ::1.
+.RE
+.sp
+\fB\-p\fP \fIport\fP
+.RS 4
+This option allows the user to specify the UDP port number which the target
+\fBchronyd\fP is using for its monitoring connections. This defaults to 323; there
+would rarely be a need to change this.
+.RE
+.sp
+\fB\-f\fP \fIfile\fP
+.RS 4
+This option is ignored and is provided only for compatibility.
+.RE
+.sp
+\fB\-a\fP
+.RS 4
+This option is ignored and is provided only for compatibility.
+.RE
+.sp
+\fB\-v\fP, \fB\-\-version\fP
+.RS 4
+With this option \fBchronyc\fP displays its version number on the terminal and
+exits.
+.RE
+.sp
+\fB\-\-help\fP
+.RS 4
+With this option \fBchronyc\fP displays a help message on the terminal and
+exits.
+.RE
+.SH "COMMANDS"
+.sp
+This section describes each of the commands available within the \fBchronyc\fP
+program.
+.SS "System clock"
+.sp
+\fBtracking\fP
+.RS 4
+The \fBtracking\fP command displays parameters about the system\(cqs clock
+performance. An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Reference ID    : CB00710F (foo.example.net)
+Stratum         : 3
+Ref time (UTC)  : Fri Jan 27 09:49:17 2017
+System time     : 0.000006523 seconds slow of NTP time
+Last offset     : \-0.000006747 seconds
+RMS offset      : 0.000035822 seconds
+Frequency       : 3.225 ppm slow
+Residual freq   : \-0.000 ppm
+Skew            : 0.129 ppm
+Root delay      : 0.013639022 seconds
+Root dispersion : 0.001100737 seconds
+Update interval : 64.2 seconds
+Leap status     : Normal
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBReference ID\fP
+.RS 4
+This is the reference ID and name (or IP address) of the server to which the
+computer is currently synchronised. For IPv4 addresses, the reference ID is
+equal to the address and for IPv6 addresses it is the first 32 bits of the MD5
+sum of the address.
+.sp
+If the reference ID is \fI7F7F0101\fP and there is no name or IP address, it means
+the computer is not synchronised to any external source and that you have the
+\fIlocal\fP mode operating (via the \fBlocal\fP command in \fBchronyc\fP, or the
+\fBlocal\fP directive in the configuration file).
+.sp
+The reference ID is printed as a hexadecimal number. Note that in older
+versions it used to be printed in quad\-dotted notation and could be confused
+with an IPv4 address.
+.RE
+.sp
+\fBStratum\fP
+.RS 4
+The stratum indicates how many hops away from a computer with an attached
+reference clock we are. Such a computer is a stratum\-1 computer, so the
+computer in the example is two hops away (i.e. \fIfoo.example.net\fP is a
+stratum\-2 and is synchronised from a stratum\-1).
+.RE
+.sp
+\fBRef time\fP
+.RS 4
+This is the time (UTC) at which the last measurement from the reference
+source was processed.
+.RE
+.sp
+\fBSystem time\fP
+.RS 4
+This is the current offset between the NTP clock and system clock. The NTP
+clock is a software (virtual) clock maintained by \fBchronyd\fP, which is
+synchronised to the configured time sources and provides time to NTP clients.
+The system clock is synchronised to the NTP clock. To avoid steps in the
+system time, which might have adverse consequences for certain applications,
+the system clock is normally corrected only by speeding up or slowing down (up
+to the rate configured by the \fBmaxslewrate\fP
+directive). If the offset is too large, this correction will take a very long
+time. A step can be forced by the \fBmakestep\fP command, or the
+\fBmakestep\fP directive in the configuration file.
+.sp
+Note that all other offsets reported by \fBchronyc\fP and most offsets in the log
+files are relative to the NTP clock, not the system clock.
+.RE
+.sp
+\fBLast offset\fP
+.RS 4
+This is the estimated local offset on the last clock update. A positive value
+indicates the local time (as previously estimated true time) was ahead of the
+time sources.
+.RE
+.sp
+\fBRMS offset\fP
+.RS 4
+This is a long\-term average of the offset value.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+The \(oqfrequency\(cq is the rate by which the system\(cqs clock would be wrong if
+\fBchronyd\fP was not correcting it. It is expressed in ppm (parts per million).
+For example, a value of 1 ppm would mean that when the system\(cqs clock thinks it
+has advanced 1 second, it has actually advanced by 1.000001 seconds relative to
+true time.
+.RE
+.sp
+\fBResidual freq\fP
+.RS 4
+This shows the \(oqresidual frequency\(cq for the currently selected reference
+source. This reflects any difference between what the measurements from the
+reference source indicate the frequency should be and the frequency currently
+being used.
+.sp
+The reason this is not always zero is that a smoothing procedure is
+applied to the frequency. Each time a measurement from the reference
+source is obtained and a new residual frequency computed, the estimated
+accuracy of this residual is compared with the estimated accuracy (see
+\(oqskew\(cq next) of the existing frequency value. A weighted average is
+computed for the new frequency, with weights depending on these accuracies.
+If the measurements from the reference source follow a consistent trend, the
+residual will be driven to zero over time.
+.RE
+.sp
+\fBSkew\fP
+.RS 4
+This is the estimated error bound on the frequency.
+.RE
+.sp
+\fBRoot delay\fP
+.RS 4
+This is the total of the network path delays to the stratum\-1 computer from
+which the computer is ultimately synchronised.
+.RE
+.sp
+\fBRoot dispersion\fP
+.RS 4
+This is the total dispersion accumulated through all the computers back to
+the stratum\-1 computer from which the computer is ultimately synchronised.
+Dispersion is due to system clock resolution, statistical measurement
+variations, etc.
+.sp
+An absolute bound on the computer\(cqs clock accuracy (assuming the stratum\-1
+computer is correct) is given by:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay)
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBUpdate interval\fP
+.RS 4
+This is the interval between the last two clock updates.
+.RE
+.sp
+\fBLeap status\fP
+.RS 4
+This is the leap status, which can be \fINormal\fP, \fIInsert second\fP, \fIDelete
+second\fP or \fINot synchronised\fP.
+.RE
+.RE
+.sp
+\fBmakestep\fP, \fBmakestep\fP \fIthreshold\fP \fIlimit\fP
+.RS 4
+Normally \fBchronyd\fP will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+the system clock might be so far adrift that this slewing process would take a
+very long time to correct the system clock.
+.sp
+The \fBmakestep\fP command can be used in this situation. There are two forms of
+the command. The first form has no parameters. It tells \fBchronyd\fP to cancel any
+remaining correction that was being slewed and jump the system clock by the
+equivalent amount, making it correct immediately.
+.sp
+The second form configures the automatic stepping, similarly to the
+\fBmakestep\fP directive. It has two parameters,
+stepping threshold (in seconds) and number of future clock updates for which
+the threshold will be active. This can be used with the \fBburst\fP
+command to quickly make a new measurement and correct the clock by stepping if
+needed, without waiting for \fBchronyd\fP to complete the measurement and update
+the clock.
+.sp
+.if n .RS 4
+.nf
+.fam C
+makestep 0.1 1
+burst 1/2
+.fam
+.fi
+.if n .RE
+.sp
+BE WARNED: Certain software will be seriously affected by such jumps in the
+system time. (That is the reason why \fBchronyd\fP uses slewing normally.)
+.RE
+.sp
+\fBmaxupdateskew\fP \fIskew\-in\-ppm\fP
+.RS 4
+This command has the same effect as the
+\fBmaxupdateskew\fP directive in the
+configuration file.
+.RE
+.sp
+\fBwaitsync\fP [\fImax\-tries\fP [\fImax\-correction\fP [\fImax\-skew\fP [\fIinterval\fP]]]]
+.RS 4
+The \fBwaitsync\fP command waits for \fBchronyd\fP to synchronise.
+.sp
+Up to four optional arguments can be specified. The first is the maximum number
+of tries before giving up and returning a non\-zero error code. When 0 is
+specified, or there are no arguments, the number of tries will not be limited.
+.sp
+The second and third arguments are the maximum allowed remaining correction of
+the system clock and the maximum allowed skew (in ppm) as reported by the
+\fBtracking\fP command in the \fBSystem time\fP and \fBSkew\fP fields. If not
+specified or zero, the value will not be checked.
+.sp
+The fourth argument is the interval specified in seconds in which the check is
+repeated. The interval is 10 seconds by default.
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+waitsync 60 0.01
+.fam
+.fi
+.if n .RE
+.sp
+which will wait up to about 10 minutes (60 times 10 seconds) for \fBchronyd\fP to
+synchronise to a source and the remaining correction to be less than 10
+milliseconds.
+.RE
+.SS "Time sources"
+.sp
+\fBsources\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+This command displays information about the current time sources that \fBchronyd\fP
+is accessing.
+.sp
+If the \fB\-a\fP option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+\fIID#XXXXXXXXXX\fP, which can be used in other commands expecting a source address.
+.sp
+The \fB\-v\fP option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
+.sp
+.if n .RS 4
+.nf
+.fam C
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+#* GPS0                          0   4   377    11   \-479ns[ \-621ns] +/\-  134ns
+^? foo.example.net               2   6   377    23   \-923us[ \-924us] +/\-   43ms
+^+ bar.example.net               1   6   377    21  \-2629us[\-2619us] +/\-   86ms
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBM\fP
+.RS 4
+This indicates the mode of the source. \fI^\fP means a server, \fI=\fP means a peer
+and \fI#\fP indicates a locally connected reference clock.
+.RE
+.sp
+\fBS\fP
+.RS 4
+This column indicates the selection state of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP indicates the best source which is currently selected for
+synchronisation.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP indicates other sources selected for synchronisation, which are combined
+with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI\-\fP indicates a source which is considered to be selectable for
+synchronisation, but not currently selected.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP indicates a source which \fBchronyd\fP thinks is a falseticker (i.e. its
+time is inconsistent with a majority of other sources, or sources specified
+with the \fBtrust\fP option).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP indicates a source whose time appears to have too much variability.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI?\fP indicates a source which is not considered to be selectable for
+synchronisation for other reasons (e.g. unreachable, not synchronised, or
+does not have enough measurements).
+.RE
+.RE
+.sp
+
+.RS 4
+The \fBselectdata\fP command can be used to get more details about
+the selection state.
+.RE
+.sp
+\fBName/IP address\fP
+.RS 4
+This shows the name or the IP address of the source, or reference ID for reference
+clocks.
+.RE
+.sp
+\fBStratum\fP
+.RS 4
+This shows the stratum of the source, as reported in its most recently
+received sample. Stratum 1 indicates a computer with a locally attached
+reference clock. A computer that is synchronised to a stratum 1 computer is
+at stratum 2. A computer that is synchronised to a stratum 2 computer is at
+stratum 3, and so on.
+.RE
+.sp
+\fBPoll\fP
+.RS 4
+This shows the rate at which the source is being polled, as a base\-2
+logarithm of the interval in seconds. Thus, a value of 6 would indicate that
+a measurement is being made every 64 seconds. \fBchronyd\fP automatically varies
+the polling rate in response to prevailing conditions.
+.RE
+.sp
+\fBReach\fP
+.RS 4
+This shows the source\(cqs reachability register printed as an octal number. The
+register has 8 bits and is updated on every received or missed packet from
+the source. A value of 377 indicates that a valid reply was received for all
+from the last eight transmissions.
+.RE
+.sp
+\fBLastRx\fP
+.RS 4
+This column shows how long ago the last good sample (which is shown in the next
+column) was received from the source. Measurements that failed some tests are
+ignored. This is normally in seconds. The letters \fIm\fP, \fIh\fP, \fId\fP or \fIy\fP indicate
+minutes, hours, days, or years.
+.RE
+.sp
+\fBLast sample\fP
+.RS 4
+This column shows the offset between the local clock and the source at the
+last measurement. The number in the square brackets shows the actual measured
+offset. This can be suffixed by \fIns\fP (indicating nanoseconds), \fIus\fP
+(indicating microseconds), \fIms\fP (indicating milliseconds), or \fIs\fP (indicating
+seconds). The number to the left of the square brackets shows the original
+measurement, adjusted to allow for any slews applied to the local clock
+since. The number following the \fI+/\-\fP indicator shows the margin of error in
+the measurement. Positive offsets indicate that the local clock is ahead of
+the source.
+.RE
+.RE
+.sp
+\fBsourcestats\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+The \fBsourcestats\fP command displays information about the drift rate and offset
+estimation process for each of the sources currently being examined by
+\fBchronyd\fP.
+.sp
+If the \fB\-a\fP option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+\fIID#XXXXXXXXXX\fP, which can be used in other commands expecting a source address.
+.sp
+The \fB\-v\fP option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
+.sp
+An example report is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+===============================================================================
+foo.example.net            11   5   46m     \-0.001      0.045      1us    25us
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBName/IP Address\fP
+.RS 4
+This is the name or IP address of the NTP server (or peer) or reference ID of the
+reference clock to which the rest of the line relates.
+.RE
+.sp
+\fBNP\fP
+.RS 4
+This is the number of sample points currently being retained for the server.
+The drift rate and current offset are estimated by performing a linear
+regression through these points.
+.RE
+.sp
+\fBNR\fP
+.RS 4
+This is the number of runs of residuals having the same sign following the
+last regression. If this number starts to become too small relative to the
+number of samples, it indicates that a straight line is no longer a good fit
+to the data. If the number of runs is too low, \fBchronyd\fP discards older
+samples and re\-runs the regression until the number of runs becomes
+acceptable.
+.RE
+.sp
+\fBSpan\fP
+.RS 4
+This is the interval between the oldest and newest samples. If no unit is
+shown the value is in seconds. In the example, the interval is 46 minutes.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+This is the estimated residual frequency for the server, in parts per
+million. In this case, the computer\(cqs clock is estimated to be running 1 part
+in 10^9 slow relative to the server.
+.RE
+.sp
+\fBFreq Skew\fP
+.RS 4
+This is the estimated error bounds on \fBFreq\fP (again in parts per million).
+.RE
+.sp
+\fBOffset\fP
+.RS 4
+This is the estimated offset of the source.
+.RE
+.sp
+\fBStd Dev\fP
+.RS 4
+This is the estimated sample standard deviation.
+.RE
+.RE
+.sp
+\fBselectdata\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+The \fBselectdata\fP command displays information specific to the selection of time
+sources. If the \fB\-a\fP option is specified, all sources are displayed, including
+those that do not have a known address yet. With the \fB\-v\fP option, extra caption
+lines are shown as a reminder of the meanings of the columns.
+.sp
+An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+D foo.example.net           Y \-\-\-\-\- \-\-TR\-    4   1.0   \-61ms   +62ms  N
+* bar.example.net           N \-\-\-\-\- \-\-\-\-\-    0   1.0 \-6846us +7305us  N
++ baz.example.net           N \-\-\-\-\- \-\-\-\-\-   10   1.0 \-7381us +7355us  N
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBS\fP
+.RS 4
+This column indicates the state of the source after the last source selection.
+It is similar to the state reported by the \fBsources\fP command, but more
+states are reported.
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is not considered selectable for
+synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP \- has the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIs\fP \- is not synchronised.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIM\fP \- does not have enough measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fId\fP \- has a root distance larger than the maximum distance (configured by the
+\fBmaxdistance\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP \- has a jitter larger than the maximum jitter (configured by the
+\fBmaxjitter\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIw\fP \- waits for other sources to get out of the \fIM\fP state.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIS\fP \- has older measurements than other sources.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIO\fP \- has a stratum equal or larger than the orphan stratum (configured by
+the \fBlocal\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP \- does not fully agree with sources that have the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP \- does not agree with other sources (falseticker).
+.RE
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is considered selectable, but it is
+not currently used for synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIW\fP \- waits for other sources to be selectable (required by the
+\fBminsources\fP directive, or
+the \fBrequire\fP option of another source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP \- another selectable source is preferred due to the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIU\fP \- waits for a new measurement (after selecting a different best source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fID\fP \- has, or recently had, a root distance which is too large to be combined
+with other sources (configured by the
+\fBcombinelimit\fP directive).
+.RE
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is used for synchronisation of the
+local clock:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP \- combined with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP \- selected as the best source to update the reference data (e.g. root
+delay, root dispersion).
+.RE
+.RE
+.sp
+\fBName/IP address\fP
+.RS 4
+This column shows the name or IP address of the source if it is an NTP server,
+or the reference ID if it is a reference clock.
+.RE
+.sp
+\fBAuth\fP
+.RS 4
+This column indicites whether an authentication mechanism is enabled for the
+source. \fIY\fP means yes and \fIN\fP means no.
+.RE
+.sp
+\fBCOpts\fP
+.RS 4
+This column displays the configured selection options of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP indicates the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP indicates the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP indicates the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIR\fP indicates the \fBrequire\fP option.
+.RE
+.RE
+.sp
+\fBEOpts\fP
+.RS 4
+This column displays the current effective selection options of the source,
+which can be different from the configured options due to the authentication
+selection mode (configured by the
+\fBauthselmode\fP directive). The symbols are the
+same as in the \fBCOpts\fP column.
+.RE
+.sp
+\fBLast\fP
+.RS 4
+This column displays how long ago was the last measurement of the source made
+when the selection was performed.
+.RE
+.sp
+\fBScore\fP
+.RS 4
+This column displays the current score against the source in the \fI*\fP state. The
+scoring system avoids frequent reselection when multiple sources have a similar
+root distance. A value larger than 1 indicates this source was better than the
+\fI*\fP source in recent selections. If the score reaches 10, the best source will
+be reselected and the scores will be reset to 1.
+.RE
+.sp
+\fBInterval\fP
+.RS 4
+This column displays the lower and upper endpoint of the interval which was
+expected to contain the true offset of the local clock considering the root
+distance at the time of the selection.
+.RE
+.sp
+\fBLeap\fP
+.RS 4
+This column displays the current leap status of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP indicates the normal status (no leap second).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP indicates that a leap second will be inserted at the end of the month.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI\-\fP indicates that a leap second will be deleted at the end of the month.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI?\fP indicates the unknown status (i.e. no valid measurement was made).
+.RE
+.RE
+.RE
+.sp
+\fBreselect\fP
+.RS 4
+To avoid excessive switching between sources, \fBchronyd\fP can stay synchronised
+to a source even when it is not currently the best one among the available
+sources.
+.sp
+The \fBreselect\fP command can be used to force \fBchronyd\fP to reselect the best
+synchronisation source.
+.RE
+.sp
+\fBreselectdist\fP \fIdistance\fP
+.RS 4
+The \fBreselectdist\fP command sets the reselection distance. It is equivalent to
+the \fBreselectdist\fP directive in the
+configuration file.
+.RE
+.SS "NTP sources"
+.sp
+\fBactivity\fP
+.RS 4
+This command reports the number of servers and peers that are online and
+offline. If the \fBauto_offline\fP option is used in specifying some of the servers
+or peers, the \fBactivity\fP command can be useful for detecting when all of them
+have entered the offline state after the network link has been disconnected.
+.sp
+The report shows the number of servers and peers in 5 states:
+.sp
+\fBonline\fP
+.RS 4
+the server or peer is currently online (i.e. assumed by \fBchronyd\fP to be reachable)
+.RE
+.sp
+\fBoffline\fP
+.RS 4
+the server or peer is currently offline (i.e. assumed by \fBchronyd\fP to be
+unreachable, and no measurements from it will be attempted.)
+.RE
+.sp
+\fBburst_online\fP
+.RS 4
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the online state.
+.RE
+.sp
+\fBburst_offline\fP
+.RS 4
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the offline state.
+.RE
+.sp
+\fBunresolved\fP
+.RS 4
+the name of the server or peer was not resolved to an address yet; this source is
+not visible in the \fBsources\fP and \fBsourcestats\fP reports.
+.RE
+.RE
+.sp
+\fBauthdata\fP [\fB\-a\fP]
+.RS 4
+The \fBauthdata\fP command displays information specific to authentication of NTP
+sources. If the \fB\-a\fP option is specified, all sources are displayed, including
+those that do not have a known address yet. An example of the output is
+shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256 135m    0    0    8  100
+bar.example.net               SK    30   13  128    \-    0    0    0    0
+baz.example.net                \-     0    0    0    \-    0    0    0    0
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBName/IP address\fP
+.RS 4
+This column shows the name or the IP address of the source.
+.RE
+.sp
+\fBMode\fP
+.RS 4
+This column shows which mechanism authenticates NTP packets received from the
+source. \fINTS\fP means Network Time Security, \fISK\fP means a symmetric key, and \fI\-\fP
+means authentication is disabled.
+.RE
+.sp
+\fBKeyID\fP
+.RS 4
+This column shows an identifier of the key used for authentication. With a
+symmetric key, it is the ID from the key file.
+With NTS, it is a number starting at zero and incremented by one with each
+successful key establishment using the NTS\-KE protocol, i.e. it shows how many
+times the key establishment was performed with this source.
+.RE
+.sp
+\fBType\fP
+.RS 4
+This columns shows an identifier of the algorithm used for authentication.
+With a symmetric key, it is the hash function or cipher specified in the key
+file. With NTS, it is an authenticated encryption with associated data (AEAD)
+algorithm, which is negotiated in the NTS\-KE protocol. The following values can
+be reported:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+1: MD5
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+2: SHA1
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+3: SHA256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+4: SHA384
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+5: SHA512
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+6: SHA3\-224
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+7: SHA3\-256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+8: SHA3\-384
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+9: SHA3\-512
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+10: TIGER
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+11: WHIRLPOOL
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+13: AES128
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+14: AES256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+15: AEAD\-AES\-SIV\-CMAC\-256
+.RE
+.RE
+.sp
+\fBKLen\fP
+.RS 4
+This column shows the length of the key in bits.
+.RE
+.sp
+\fBLast\fP
+.RS 4
+This column shows how long ago the last successful key establishment was
+performed. It is in seconds, or letters \fIm\fP, \fIh\fP, \fId\fP or \fIy\fP indicate minutes,
+hours, days, or years.
+.RE
+.sp
+\fBAtmp\fP
+.RS 4
+This column shows the number of attempts to perform the key establishment since
+the last successful key establishment. A number larger than 1 indicates a
+problem with the network or server.
+.RE
+.sp
+\fBNAK\fP
+.RS 4
+This column shows whether an NTS NAK was received since the last request.
+A NAK indicates that authentication failed on the server side due to
+\fBchronyd\fP using a cookie which is no longer valid and that it needs to perform
+the key establishment again in order to get new cookies.
+.RE
+.sp
+\fBCook\fP
+.RS 4
+This column shows the number of NTS cookies that \fBchronyd\fP currently has. If
+the key establishment was successful, a number smaller than 8 indicates a
+problem with the network or server.
+.RE
+.sp
+\fBCLen\fP
+.RS 4
+This column shows the length in bytes of the NTS cookie which will be used in
+the next request.
+.RE
+.RE
+.sp
+\fBntpdata\fP [\fIaddress\fP]
+.RS 4
+The \fBntpdata\fP command displays the last valid measurement and other
+NTP\-specific information about the specified NTP source, or all NTP sources
+(with a known address) if no address was specified. An example of the output is
+shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Remote address  : 203.0.113.15 (CB00710F)
+Remote port     : 123
+Local address   : 203.0.113.74 (CB00714A)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 10 (1024 seconds)
+Precision       : \-24 (0.000000060 seconds)
+Root delay      : 0.000015 seconds
+Root dispersion : 0.000015 seconds
+Reference ID    : 47505300 (GPS)
+Reference time  : Fri Nov 25 15:22:12 2016
+Offset          : \-0.000060878 seconds
+Peer delay      : 0.000175634 seconds
+Peer dispersion : 0.000000681 seconds
+Response time   : 0.000053050 seconds
+Jitter asymmetry: +0.00
+NTP tests       : 111 111 1111
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 24
+Total RX        : 24
+Total valid RX  : 24
+Total good RX   : 22
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBRemote address\fP
+.RS 4
+The IP address of the NTP server or peer, and the corresponding reference ID.
+.RE
+.sp
+\fBRemote port\fP
+.RS 4
+The UDP port number to which the request was sent. The standard NTP port is
+123.
+.RE
+.sp
+\fBLocal address\fP
+.RS 4
+The local IP address which received the response, and the corresponding
+reference ID.
+.RE
+.sp
+\fBLeap status\fP, \fBVersion\fP, \fBMode\fP, \fBStratum\fP, \fBPoll interval\fP, \fBPrecision\fP, \fBRoot delay\fP, \fBRoot dispersion\fP, \fBReference ID\fP, \fBReference time\fP
+.RS 4
+The NTP values from the last valid response.
+.RE
+.sp
+\fBOffset\fP, \fBPeer delay\fP, \fBPeer dispersion\fP
+.RS 4
+The measured values.
+.RE
+.sp
+\fBResponse time\fP
+.RS 4
+The time the server or peer spent in processing of the request and waiting
+before sending the response.
+.RE
+.sp
+\fBJitter asymmetry\fP
+.RS 4
+The estimated asymmetry of network jitter on the path to the source. The
+asymmetry can be between \-0.5 and 0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent
+from the source back.
+.RE
+.sp
+\fBNTP tests\fP
+.RS 4
+Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum
+delay, delay ratio, delay dev ratio (or delay quantile), and synchronisation
+loop.
+.RE
+.sp
+\fBInterleaved\fP
+.RS 4
+This shows if the response was in the interleaved mode.
+.RE
+.sp
+\fBAuthenticated\fP
+.RS 4
+This shows if the response was authenticated.
+.RE
+.sp
+\fBTX timestamping\fP
+.RS 4
+The source of the local transmit timestamp. Valid values are \fIDaemon\fP,
+\fIKernel\fP, and \fIHardware\fP.
+.RE
+.sp
+\fBRX timestamping\fP
+.RS 4
+The source of the local receive timestamp.
+.RE
+.sp
+\fBTotal TX\fP
+.RS 4
+The number of packets sent to the source.
+.RE
+.sp
+\fBTotal RX\fP
+.RS 4
+The number of all packets received from the source.
+.RE
+.sp
+\fBTotal valid RX\fP
+.RS 4
+The number of packets which passed the first two groups of NTP tests.
+.RE
+.sp
+\fBTotal good RX\fP
+.RS 4
+The number of packets which passed all three groups of NTP tests, i.e. the NTP
+measurement was accepted.
+.RE
+.RE
+.sp
+\fBadd peer\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd peer\fP command allows a new NTP peer to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd peer\fP, the syntax of the following
+parameters and options is identical to that for the
+\fBpeer\fP directive in the configuration file.
+.sp
+An example of using this command is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+add peer foo.example.net minpoll 6 maxpoll 10 key 25
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBadd pool\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd pool\fP command allows a pool of NTP servers to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd pool\fP, the syntax of the following parameters and
+options is identical to that for the \fBpool\fP
+directive in the configuration file.
+.sp
+An example of using this command is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+add pool foo.example.net maxsources 3 iburst
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBadd server\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd server\fP command allows a new NTP server to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd server\fP, the syntax of the following parameters and
+options is identical to that for the \fBserver\fP
+directive in the configuration file.
+.sp
+An example of using this command is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+add server foo.example.net minpoll 6 maxpoll 10 key 25
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdelete\fP \fIaddress\fP
+.RS 4
+The \fBdelete\fP command allows an NTP server or peer to be removed
+from the current set of sources.
+.RE
+.sp
+\fBburst\fP \fIgood\fP/\fImax\fP [\fImask\fP/\fImasked\-address\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fIaddress\fP]
+.RS 4
+The \fBburst\fP command tells \fBchronyd\fP to make a set of measurements to each of
+its NTP sources over a short duration (rather than the usual periodic
+measurements that it makes). After such a burst, \fBchronyd\fP will revert to the
+previous state for each source. This might be either online, if the source was
+being periodically measured in the normal way, or offline, if the source had
+been indicated as being offline. (A source can be switched between the online
+and offline states with the \fBonline\fP and \fBoffline\fP
+commands.)
+.sp
+The \fImask\fP and \fImasked\-address\fP arguments are optional, in which case \fBchronyd\fP
+will initiate a burst for all of its currently defined sources.
+.sp
+The arguments have the following meaning and format:
+.sp
+\fIgood\fP
+.RS 4
+This defines the number of good measurements that \fBchronyd\fP will want to
+obtain from each source. A measurement is good if it passes certain tests,
+for example, the round trip time to the source must be acceptable. (This
+allows \fBchronyd\fP to reject measurements that are likely to be bogus.)
+.RE
+.sp
+\fImax\fP
+.RS 4
+This defines the maximum number of measurements that \fBchronyd\fP will attempt
+to make, even if the required number of good measurements has not been
+obtained.
+.RE
+.sp
+\fImask\fP
+.RS 4
+This is an IP address with which the IP address of each of \fBchronyd\fP\(aqs
+sources is to be masked.
+.RE
+.sp
+\fImasked\-address\fP
+.RS 4
+This is an IP address. If the masked IP address of a source matches this
+value then the burst command is applied to that source.
+.RE
+.sp
+\fImasked\-bits\fP
+.RS 4
+This can be used with \fImasked\-address\fP for CIDR notation, which is a shorter
+alternative to the form with mask.
+.RE
+.sp
+\fIaddress\fP
+.RS 4
+This is an IP address or a hostname. The burst command is applied only to
+that source.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+If no \fImask\fP or \fImasked\-address\fP arguments are provided, every source will be
+matched.
+.sp
+An example of the two\-argument form of the command is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10
+.fam
+.fi
+.if n .RE
+.sp
+This will cause \fBchronyd\fP to attempt to get two good measurements from each
+source, stopping after two have been obtained, but in no event will it try more
+than ten probes to the source.
+.sp
+Examples of the four\-argument form of the command are:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10 255.255.0.0/1.2.0.0
+burst 2/10 2001:db8:789a::/48
+.fam
+.fi
+.if n .RE
+.sp
+In the first case, the two out of ten sampling will only be applied to sources
+whose IPv4 addresses are of the form \fI1.2.x.y\fP, where \fIx\fP and \fIy\fP are
+arbitrary. In the second case, the sampling will be applied to sources whose
+IPv6 addresses have first 48 bits equal to \fI2001:db8:789a\fP.
+.sp
+Example of the three\-argument form of the command is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10 foo.example.net
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmaxdelay\fP \fIaddress\fP \fIdelay\fP
+.RS 4
+This allows the \fBmaxdelay\fP option for one of the sources to be modified, in the
+same way as specifying the \fBmaxdelay\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxdelaydevratio\fP \fIaddress\fP \fIratio\fP
+.RS 4
+This allows the \fBmaxdelaydevratio\fP option for one of the sources to be
+modified, in the same way as specifying the \fBmaxdelaydevratio\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxdelayratio\fP \fIaddress\fP \fIratio\fP
+.RS 4
+This allows the \fBmaxdelayratio\fP option for one of the sources to be modified,
+in the same way as specifying the \fBmaxdelayratio\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxpoll\fP \fIaddress\fP \fImaxpoll\fP
+.RS 4
+The \fBmaxpoll\fP command is used to modify the maximum polling interval for one of
+the current set of sources. It is equivalent to the \fBmaxpoll\fP option in the
+\fBserver\fP directive in the configuration file.
+.sp
+Note that the new maximum polling interval only takes effect after the next
+measurement has been made.
+.RE
+.sp
+\fBminpoll\fP \fIaddress\fP \fIminpoll\fP
+.RS 4
+The \fBminpoll\fP command is used to modify the minimum polling interval for one of
+the current set of sources. It is equivalent to the \fBminpoll\fP option in the
+\fBserver\fP directive in the configuration file.
+.sp
+Note that the new minimum polling interval only takes effect after the next
+measurement has been made.
+.RE
+.sp
+\fBminstratum\fP \fIaddress\fP \fIminstratum\fP
+.RS 4
+The \fBminstratum\fP command is used to modify the minimum stratum for one of the
+current set of sources. It is equivalent to the \fBminstratum\fP option in the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBoffline\fP [\fIaddress\fP], \fBoffline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBoffline\fP [\fImask\fP/\fImasked\-address\fP]
+.RS 4
+The \fBoffline\fP command is used to warn \fBchronyd\fP that the network connection to
+a particular host or hosts is about to be lost, e.g. on computers with
+intermittent connection to their time sources.
+.sp
+Another case where \fBoffline\fP could be used is where a computer serves time to a
+local group of computers, and has a permanent connection to true time servers
+outside the organisation. However, the external connection is heavily loaded at
+certain times of the day and the measurements obtained are less reliable at
+those times. In this case, it is probably most useful to determine the
+gain or loss rate during the quiet periods and let the whole network coast through
+the loaded periods. The \fBoffline\fP and \fBonline\fP commands can be used to achieve
+this.
+.sp
+There are four forms of the \fBoffline\fP command. The first form is a wildcard,
+meaning all sources (including sources that do not have a known address yet).
+The second form allows an IP address mask and a masked
+address to be specified. The third form uses CIDR notation. The fourth form
+uses an IP address or a hostname. These forms are illustrated below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+offline
+offline 255.255.255.0/1.2.3.0
+offline 2001:db8:789a::/48
+offline foo.example.net
+.fam
+.fi
+.if n .RE
+.sp
+The second form means that the \fBoffline\fP command is to be applied to any source
+whose IPv4 address is in the \fI1.2.3\fP subnet. (The host\(cqs address is logically
+and\-ed with the mask, and if the result matches the \fImasked\-address\fP the host
+is processed.) The third form means that the command is to be applied to all
+sources whose IPv6 addresses have their first 48 bits equal to \fI2001:db8:789a\fP. The
+fourth form means that the command is to be applied only to that one source.
+.sp
+The wildcard form of the address is equivalent to:
+.sp
+.if n .RS 4
+.nf
+.fam C
+offline 0.0.0.0/0.0.0.0
+offline ::/0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBonline\fP [\fIaddress\fP], \fBonline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBonline\fP [\fImask\fP/\fImasked\-address\fP]
+.RS 4
+The \fBonline\fP command is opposite in function to the \fBoffline\fP
+command. It is used to advise \fBchronyd\fP that network connectivity to a
+particular source or sources has been restored.
+.sp
+The syntax is identical to that of the \fBoffline\fP command.
+.RE
+.sp
+\fBonoffline\fP
+.RS 4
+The \fBonoffline\fP command tells \fBchronyd\fP to switch all sources that have a known
+address to the online or
+offline status according to the current network configuration. A source is
+considered online if it is possible to send requests to it, i.e. a network
+route to the source is present.
+.RE
+.sp
+\fBpolltarget\fP \fIaddress\fP \fIpolltarget\fP
+.RS 4
+The \fBpolltarget\fP command is used to modify the poll target for one of the
+current set of sources. It is equivalent to the \fBpolltarget\fP option in the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBrefresh\fP
+.RS 4
+The \fBrefresh\fP command can be used to force \fBchronyd\fP to resolve the names of
+configured sources to IP addresses again, e.g. after suspending and resuming
+the machine in a different network.
+.sp
+Sources that stop responding will be replaced with newly resolved addresses
+automatically after 8 polling intervals, but this command can still be useful
+to replace them immediately and not wait until they are marked as unreachable.
+.RE
+.sp
+\fBreload\fP \fBsources\fP
+.RS 4
+The \fBreload sources\fP command causes \fBchronyd\fP to re\-read all \fI*.sources\fP files
+from the directories specified by the
+\fBsourcedir\fP directive.
+.RE
+.sp
+\fBsourcename\fP \fIaddress\fP
+.RS 4
+The \fBsourcename\fP command prints the original hostname or address that was
+specified for an NTP source in the configuration file, or the \fBadd\fP command.
+This command is an alternative to the \fB\-N\fP option, which can be useful in
+scripts.
+.sp
+Note that different NTP sources can share the same name, e.g. servers from a
+pool.
+.RE
+.SS "Manual time input"
+.sp
+\fBmanual\fP \fBon\fP, \fBmanual\fP \fBoff\fP, \fBmanual\fP \fBdelete\fP \fIindex\fP, \fBmanual\fP \fBlist\fP, \fBmanual\fP \fBreset\fP
+.RS 4
+The manual command enables and disables use of the \fBsettime\fP
+command, and is used to modify the behaviour of the manual clock driver.
+.sp
+The \fBon\fP form of the command enables use of the \fBsettime\fP command.
+.sp
+The \fBoff\fP form of the command disables use of the \fBsettime\fP command.
+.sp
+The \fBlist\fP form of the command lists all the samples currently stored in
+\fBchronyd\fP. The output is illustrated below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+210 n_samples = 1
+#    Date  Time(UTC)    Slewed   Original   Residual
+====================================================
+ 0 27Jan99 22:09:20       0.00       0.97       0.00
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as as follows:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+The sample index (used for the \fBmanual delete\fP command).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The date and time of the sample.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The system clock error when the timestamp was entered, adjusted to allow
+for changes made to the system clock since.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The system clock error when the timestamp was entered, as it originally was
+(without allowing for changes to the system clock since).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The regression residual at this point, in seconds. This allows \(oqoutliers\(cq
+to be easily spotted, so that they can be deleted using the \fBmanual delete\fP
+command.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+The \fBdelete\fP form of the command deletes a single sample. The parameter is the
+index of the sample, as shown in the first column of the output from \fBmanual
+list\fP. Following deletion of the data point, the current error and drift rate
+are re\-estimated from the remaining data points and the system clock trimmed if
+necessary. This option is intended to allow \(oqoutliers\(cq to be discarded, i.e.
+samples where the administrator realises they have entered a very poor
+timestamp.
+.sp
+The \fBreset\fP form of the command deletes all samples at once. The system clock
+is left running as it was before the command was entered.
+.RE
+.sp
+\fBsettime\fP \fItime\fP
+.RS 4
+The \fBsettime\fP command allows the current time to be entered manually, if this
+option has been configured into \fBchronyd\fP. (It can be configured either with
+the \fBmanual\fP directive in the configuration file,
+or with the \fBmanual\fP command of \fBchronyc\fP.)
+.sp
+It should be noted that the computer\(cqs sense of time will only be as accurate
+as the reference you use for providing this input (e.g. your watch), as well as
+how well you can time the press of the return key.
+.sp
+Providing your computer\(cqs time zone is set up properly, you will be able to
+enter a local time (rather than UTC).
+.sp
+The response to a successful \fBsettime\fP command indicates the amount that the
+computer\(cqs clock was wrong. It should be apparent from this if you have entered
+the time wrongly, e.g. with the wrong time zone.
+.sp
+The rate of drift of the system clock is estimated by a regression process
+using the entered measurement and all previous measurements entered during the
+present run of \fBchronyd\fP. However, the entered measurement is used for
+adjusting the current clock offset (rather than the estimated intercept from
+the regression, which is ignored). Contrast what happens with the
+\fBmanual delete\fP command, where the intercept is used to set the
+current offset (since there is no measurement that has just been entered in
+that case).
+.sp
+The time is parsed by the public domain \fIgetdate\fP algorithm. Consequently, you
+can only specify time to the nearest second.
+.sp
+Examples of inputs that are valid are shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+settime 16:30
+settime 16:30:05
+settime Nov 21, 2015 16:30:05
+.fam
+.fi
+.if n .RE
+.sp
+For a full description of getdate, see the getdate documentation
+(bundled, for example, with the source for GNU tar).
+.RE
+.SS "NTP access"
+.sp
+\fBaccheck\fP \fIaddress\fP
+.RS 4
+This command allows you to check whether client NTP access is allowed from a
+particular host.
+.sp
+Examples of use, showing a named host and a numeric IP address, are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+accheck foo.example.net
+accheck 1.2.3.4
+accheck 2001:db8::1
+.fam
+.fi
+.if n .RE
+.sp
+This command can be used to examine the effect of a series of \fBallow\fP, \fBallow
+all\fP, \fBdeny\fP, and \fBdeny all\fP commands specified either via \fBchronyc\fP, or in
+\fBchronyd\fP\(aqs configuration file.
+.RE
+.sp
+\fBclients\fP [\fB\-p\fP \fIpackets\fP] [\fB\-k\fP] [\fB\-r\fP]
+.RS 4
+This command shows a list of clients that have accessed the server, through
+the NTP, command, or NTS\-KE port. It does not include accesses over the Unix
+domain command socket.
+.sp
+The \fB\-p\fP option specifies the minimum number of received NTP or command
+packets, or accepted NTS\-KE connections, needed to include a client in the
+list. The default value is 0, i.e. all clients are reported. With the \fB\-k\fP
+option the last four columns will show the NTS\-KE accesses instead of command
+accesses. If the \fB\-r\fP option is specified, \fBchronyd\fP will reset the counters of
+received and dropped packets or connections after reporting the current values.
+.sp
+An example of the output is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+localhost                       2      0   2   \-   133      15      0  \-1     7
+foo.example.net                12      0   6   \-    23       0      0   \-     \-
+.fam
+.fi
+.if n .RE
+.sp
+Each row shows the data for a single host. Only hosts that have passed the host
+access checks (set with the \fBallow\fP, \fBdeny\fP,
+\fBcmdallow\fP and \fBcmddeny\fP commands or configuration
+file directives) are logged. The intervals are displayed as a power of 2 in
+seconds.
+.sp
+The columns are as follows:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+The hostname of the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The number of NTP packets received from the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The number of NTP packets dropped to limit the response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The average interval between NTP packets.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The average interval between NTP packets after limiting the response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Time since the last NTP packet was received
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The number of command packets or NTS\-KE connections received/accepted from
+the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The number of command packets or NTS\-KE connections dropped to limit the
+response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The average interval between command packets or NTS\-KE connections.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+Time since the last command packet or NTS\-KE connection was
+received/accepted.
+.RE
+.RE
+.sp
+\fBserverstats\fP
+.RS 4
+The \fBserverstats\fP command displays NTP and command server statistics.
+.sp
+An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+NTP packets received       : 1598
+NTP packets dropped        : 8
+Command packets received   : 19
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS\-KE connections accepted: 3
+NTS\-KE connections dropped : 0
+Authenticated NTP packets  : 189
+Interleaved NTP packets    : 43
+NTP timestamps held        : 44
+NTP timestamp span         : 120
+.fam
+.fi
+.if n .RE
+.sp
+The fields have the following meaning:
+.sp
+\fBNTP packets received\fP
+.RS 4
+The number of valid NTP requests received by the server.
+.RE
+.sp
+\fBNTP packets dropped\fP
+.RS 4
+The number of NTP requests dropped by the server due to rate limiting
+(configured by the \fBratelimit\fP directive).
+.RE
+.sp
+\fBCommand packets received\fP
+.RS 4
+The number of command requests received by the server.
+.RE
+.sp
+\fBCommand packets dropped\fP
+.RS 4
+The number of command requests dropped by the server due to rate limiting
+(configured by the \fBcmdratelimit\fP directive).
+.RE
+.sp
+\fBClient log records dropped\fP
+.RS 4
+The number of client log records dropped by the server to limit the memory use
+(configured by the \fBclientloglimit\fP
+directive).
+.RE
+.sp
+\fBNTS\-KE connections accepted\fP
+.RS 4
+The number of NTS\-KE connections accepted by the server.
+.RE
+.sp
+\fBNTS\-KE connections dropped\fP
+.RS 4
+The number of NTS\-KE connections dropped by the server due to rate limiting
+(configured by the \fBntsratelimit\fP directive).
+.RE
+.sp
+\fBAuthenticated NTP packets\fP
+.RS 4
+The number of received NTP requests that were authenticated (with a symmetric
+key or NTS).
+.RE
+.sp
+\fBInterleaved NTP packets\fP
+.RS 4
+The number of received NTP requests that were detected to be in the interleaved
+mode.
+.RE
+.sp
+\fBNTP timestamps held\fP
+.RS 4
+The number of pairs of receive and transmit timestamps that the server is
+currently holding in memory for clients using the interleaved mode.
+.RE
+.sp
+\fBNTP timestamp span\fP
+.RS 4
+The interval (in seconds) covered by the currently held NTP timestamps.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Note that the numbers reported by this overflow to zero after 4294967295
+(32\-bit values).
+.RE
+.sp
+\fBallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The effect of the allow command is identical to the
+\fBallow\fP directive in the configuration file.
+.sp
+The syntax is illustrated in the following examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+allow all 3.4.5.0/24
+allow 2001:db8:789a::/48
+allow 0/0
+allow ::/0
+allow
+allow all
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The effect of the allow command is identical to the
+\fBdeny\fP directive in the configuration file.
+.sp
+The syntax is illustrated in the following examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+deny 1.2.3.4
+deny all 3.4.5.0/24
+deny 2001:db8:789a::/48
+deny 0/0
+deny ::/0
+deny
+deny all
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBlocal\fP [\fIoption\fP]..., \fBlocal\fP \fBoff\fP
+.RS 4
+The \fBlocal\fP command allows \fBchronyd\fP to be told that it is to appear as a
+reference source, even if it is not itself properly synchronised to an external
+source. (This can be used on isolated networks, to allow one computer to be a
+master time server with the other computers slaving to it.)
+.sp
+The first form enables the local reference mode on the host. The syntax is
+identical to the \fBlocal\fP directive in the
+configuration file.
+.sp
+The second form disables the local reference mode.
+.RE
+.sp
+\fBsmoothing\fP
+.RS 4
+The \fBsmoothing\fP command displays the current state of the NTP server time
+smoothing, which can be enabled with the
+\fBsmoothtime\fP directive. An example of the
+output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Active         : Yes
+Offset         : +1.000268817 seconds
+Frequency      : \-0.142859 ppm
+Wander         : \-0.010000 ppm per second
+Last update    : 17.8 seconds ago
+Remaining time : 19988.4 seconds
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBActive\fP
+.RS 4
+This shows if the server time smoothing is currently active. Possible values
+are \fIYes\fP and \fINo\fP. If the \fBleaponly\fP option is included in the \fBsmoothtime\fP
+directive, \fI(leap second only)\fP will be shown on the line.
+.RE
+.sp
+\fBOffset\fP
+.RS 4
+This is the current offset applied to the time sent to NTP clients. Positive
+value means the clients are getting time that\(cqs ahead of true time.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+The current frequency offset of the served time. Negative value means the
+time observed by clients is running slower than true time.
+.RE
+.sp
+\fBWander\fP
+.RS 4
+The current frequency wander of the served time. Negative value means the
+time observed by clients is slowing down.
+.RE
+.sp
+\fBLast update\fP
+.RS 4
+This field shows how long ago the time smoothing process was updated, e.g.
+\fBchronyd\fP accumulated a new measurement.
+.RE
+.sp
+\fBRemaining time\fP
+.RS 4
+The time it would take for the smoothing process to get to zero offset and
+frequency if there were no more updates.
+.RE
+.RE
+.sp
+\fBsmoothtime\fP \fBactivate\fP, \fBsmoothtime\fP \fBreset\fP
+.RS 4
+The \fBsmoothtime\fP command can be used to activate or reset the server time
+smoothing process if it is configured with the
+\fBsmoothtime\fP directive.
+.RE
+.SS "Monitoring access"
+.sp
+\fBcmdaccheck\fP \fIaddress\fP
+.RS 4
+This command is similar to the \fBaccheck\fP command, except that it is
+used to check whether monitoring access is permitted from a named host.
+.sp
+Examples of use are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdaccheck foo.example.net
+cmdaccheck 1.2.3.4
+cmdaccheck 2001:db8::1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcmdallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP command, except that it is used to
+allow particular hosts or subnets to use \fBchronyc\fP to monitor with \fBchronyd\fP on
+the current host.
+.RE
+.sp
+\fBcmddeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBdeny\fP command, except that it is used to allow
+particular hosts or subnets to use \fBchronyc\fP to monitor \fBchronyd\fP on the
+current host.
+.RE
+.SS "Real\-time clock (RTC)"
+.sp
+\fBrtcdata\fP
+.RS 4
+The \fBrtcdata\fP command displays the current RTC parameters.
+.sp
+An example output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+RTC ref time (GMT) : Sat May 30 07:25:56 2015
+Number of samples  : 10
+Number of runs     : 5
+Sample span period :  549
+RTC is fast by     :    \-1.632736 seconds
+RTC gains time at  :  \-107.623 ppm
+.fam
+.fi
+.if n .RE
+.sp
+The fields have the following meaning:
+.sp
+\fBRTC ref time (GMT)\fP
+.RS 4
+This is the RTC reading the last time its error was measured.
+.RE
+.sp
+\fBNumber of samples\fP
+.RS 4
+This is the number of previous measurements being used to determine the RTC
+gain or loss rate.
+.RE
+.sp
+\fBNumber of runs\fP
+.RS 4
+This is the number of runs of residuals of the same sign following the
+regression fit for (RTC error) versus (RTC time). A value which is small
+indicates that the measurements are not well approximated by a linear model,
+and that the algorithm will tend to delete the older measurements to improve
+the fit.
+.RE
+.sp
+\fBSample span period\fP
+.RS 4
+This is the period that the measurements span (from the oldest to the
+newest). Without a unit the value is in seconds; suffixes \fIm\fP for minutes,
+\fIh\fP for hours, \fId\fP for days or \fIy\fP for years can be used.
+.RE
+.sp
+\fBRTC is fast by\fP
+.RS 4
+This is the estimate of how many seconds fast the RTC when it thought
+the time was at the reference time (above). If this value is large, you
+might (or might not) want to use the \fBtrimrtc\fP command to bring the
+RTC into line with the system clock. (Note, a large error will not affect
+\fBchronyd\fP\(aqs operation, unless it becomes so big as to start causing rounding
+errors.)
+.RE
+.sp
+\fBRTC gains time at\fP
+.RS 4
+This is the amount of time gained (positive) or lost (negative) by the real
+time clock for each second that it ticks. It is measured in parts per
+million. So if the value shown was +1, suppose the RTC was exactly right when
+it crosses a particular second boundary. Then it would be 1 microsecond fast
+when it crosses its next second boundary.
+.RE
+.RE
+.sp
+\fBtrimrtc\fP
+.RS 4
+The \fBtrimrtc\fP command is used to correct the system\(cqs real\-time clock (RTC) to
+the main system clock. It has no effect if the error between the two clocks is
+currently estimated at less than a second.
+.sp
+The command takes no arguments. It performs the following steps (if the RTC is
+more than 1 second away from the system clock):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Remember the currently estimated gain or loss rate of the RTC and flush the
+previous measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Step the real\-time clock to bring it within a second of the system clock.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Make several measurements to accurately determine the new offset between
+the RTC and the system clock (i.e. the remaining fraction of a second
+error).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Save the RTC parameters to the RTC file (specified with the
+\fBrtcfile\fP directive in the configuration file).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+The last step is done as a precaution against the computer suffering a power
+failure before either the daemon exits or the \fBwritertc\fP command
+is issued.
+.sp
+\fBchronyd\fP will still work perfectly well both whilst operating and across
+machine reboots even if the \fBtrimrtc\fP command is never used (and the RTC is
+allowed to drift away from true time). The \fBtrimrtc\fP command is provided as a
+method by which it can be corrected, in a manner compatible with \fBchronyd\fP
+using it to maintain accurate time across machine reboots.
+.sp
+The \fBtrimrtc\fP command can be executed automatically by \fBchronyd\fP with the
+\fBrtcautotrim\fP directive in the configuration
+file.
+.RE
+.sp
+\fBwritertc\fP
+.RS 4
+The \fBwritertc\fP command writes the currently estimated error and gain or loss rate
+parameters for the RTC to the RTC file (specified with the
+\fBrtcfile\fP directive). This information is also
+written automatically when \fBchronyd\fP is killed (by the SIGHUP, SIGINT, SIGQUIT
+or SIGTERM signals) or when the \fBtrimrtc\fP command is issued.
+.RE
+.SS "Other daemon commands"
+.sp
+\fBcyclelogs\fP
+.RS 4
+The \fBcyclelogs\fP command causes all of \fBchronyd\fP\(aqs open log files to be closed
+and re\-opened. This allows them to be renamed so that they can be periodically
+purged. An example of how to do this is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+# mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
+# chronyc cyclelogs
+# rm /var/log/chrony/measurements1.log
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdump\fP
+.RS 4
+The \fBdump\fP command causes \fBchronyd\fP to write its current history of
+measurements for each of its sources to dump files in the directory specified
+in the configuration file by the \fBdumpdir\fP
+directive and also write server NTS keys and client NTS cookies to the
+directory specified by the \fBntsdumpdir\fP
+directive. Note that \fBchronyd\fP does this automatically when it exits. This
+command is mainly useful for inspection whilst \fBchronyd\fP is running.
+.RE
+.sp
+\fBrekey\fP
+.RS 4
+The \fBrekey\fP command causes \fBchronyd\fP to re\-read the key file specified in the
+configuration file by the \fBkeyfile\fP directive. It
+also re\-reads the server NTS keys if
+\fBntsdumpdir\fP is specified and
+automatic rotation is disabled in the
+configuration file.
+.RE
+.sp
+\fBreset\fP \fBsources\fP
+.RS 4
+The \fBreset sources\fP command causes \fBchronyd\fP to drop all measurements and
+switch to the unsynchronised state. This command can help \fBchronyd\fP with
+recovery when the measurements are known to be no longer valid or accurate,
+e.g. due to moving the computer to a different network, or resuming the
+computer from a low\-power state (which resets the system clock). \fBchronyd\fP will
+drop the measurements automatically when it detects the clock has made an
+unexpected jump, but the detection is not completely reliable.
+.RE
+.sp
+\fBshutdown\fP
+.RS 4
+The \fBshutdown\fP command causes \fBchronyd\fP to exit. This is equivalent to sending
+the process the SIGTERM signal.
+.RE
+.SS "Client commands"
+.sp
+\fBdns\fP \fIoption\fP
+.RS 4
+The \fBdns\fP command configures how hostnames and IP addresses are resolved in
+\fBchronyc\fP. IP addresses can be resolved to hostnames when printing results of
+\fBsources\fP, \fBsourcestats\fP, \fBtracking\fP
+and \fBclients\fP commands. Hostnames are resolved in commands that
+take an address as argument.
+.sp
+There are five options:
+.sp
+\fBdns \-n\fP
+.RS 4
+Disables resolving IP addresses to hostnames. Raw IP addresses will be
+displayed.
+.RE
+.sp
+\fBdns +n\fP
+.RS 4
+Enables resolving IP addresses to hostnames. This is the default unless
+\fBchronyc\fP was started with \fB\-n\fP option.
+.RE
+.sp
+\fBdns \-4\fP
+.RS 4
+Resolves hostnames only to IPv4 addresses.
+.RE
+.sp
+\fBdns \-6\fP
+.RS 4
+Resolves hostnames only to IPv6 addresses.
+.RE
+.sp
+\fBdns \-46\fP
+.RS 4
+Resolves hostnames to both address families. This is the default behaviour
+unless \fBchronyc\fP was started with the \fB\-4\fP or \fB\-6\fP option.
+.RE
+.RE
+.sp
+\fBtimeout\fP \fItimeout\fP
+.RS 4
+The \fBtimeout\fP command sets the initial timeout for \fBchronyc\fP requests in
+milliseconds. If no response is received from \fBchronyd\fP, the timeout is doubled
+and the request is resent. The maximum number of retries is configured with the
+\fBretries\fP command.
+.sp
+By default, the timeout is 1000 milliseconds.
+.RE
+.sp
+\fBretries\fP \fIretries\fP
+.RS 4
+The \fBretries\fP command sets the maximum number of retries for \fBchronyc\fP requests
+before giving up. The response timeout is controlled by the
+\fBtimeout\fP command.
+.sp
+The default is 2.
+.RE
+.sp
+\fBkeygen\fP [\fIid\fP [\fItype\fP [\fIbits\fP]]]
+.RS 4
+The \fBkeygen\fP command generates a key that can be added to the
+key file (specified with the \fBkeyfile\fP directive)
+to allow NTP authentication between server and client, or peers. The key is
+generated from the \fI/dev/urandom\fP device and it is printed to standard output.
+.sp
+The command has three optional arguments. The first argument is the key number
+(by default 1), which will be specified with the \fBkey\fP option of the \fBserver\fP
+or \fBpeer\fP directives in the configuration file. The second argument is the name
+of the hash function or cipher (by default SHA1, or MD5 if SHA1 is not
+available). The third argument is the length of the key in bits if a hash
+function was selected, between 80 and 4096 bits (by default 160 bits).
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keygen 73 SHA1 256
+.fam
+.fi
+.if n .RE
+.sp
+which generates a 256\-bit SHA1 key with number 73. The printed line should
+then be securely transferred and added to the key files on both server and
+client, or peers. A different key should be generated for each client or peer.
+.sp
+An example using the AES128 cipher is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keygen 151 AES128
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBexit\fP, \fBquit\fP
+.RS 4
+The \fBexit\fP and \fBquit\fP commands exit from \fBchronyc\fP and return the user to the shell.
+.RE
+.sp
+\fBhelp\fP
+.RS 4
+The \fBhelp\fP command displays a summary of the commands and their arguments.
+.RE
+.SH "SEE ALSO"
+.sp
+\fBchrony.conf(5)\fP, \fBchronyd(8)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony.tuxfamily.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/chronyd.adoc b/doc/chronyd.adoc
new file mode 100644
index 0000000..7ba991d
--- /dev/null
+++ b/doc/chronyd.adoc
@@ -0,0 +1,222 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2009-2017
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chronyd(8)
+:doctype: manpage
+:man manual: System Administration
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+
+chronyd - chrony daemon
+
+== SYNOPSIS
+
+*chronyd* [_OPTION_]... [_DIRECTIVE_]...
+
+== DESCRIPTION
+
+*chronyd* is a daemon for synchronisation of the system clock. It can
+synchronise the clock with NTP servers, reference clocks (e.g. a GPS receiver),
+and manual input using wristwatch and keyboard via *chronyc*. It can also
+operate as an NTPv4 (RFC 5905) server and peer to provide a time service to
+other computers in the network.
+
+If no configuration directives are specified on the command line, *chronyd*
+will read them from a configuration file. The compiled-in default location of
+the file is _@SYSCONFDIR@/chrony.conf_.
+
+Informational messages, warnings, and errors will be logged to syslog.
+
+== OPTIONS
+
+*-4*::
+With this option hostnames will be resolved only to IPv4 addresses and only
+IPv4 sockets will be created.
+
+*-6*::
+With this option hostnames will be resolved only to IPv6 addresses and only
+IPv6 sockets will be created.
+
+*-f* _file_::
+This option can be used to specify an alternate location for the configuration
+file. The compiled-in default value is _@SYSCONFDIR@/chrony.conf_.
+
+*-n*::
+When run in this mode, the program will not detach itself from the terminal.
+
+*-d*::
+When run in this mode, the program will not detach itself from the terminal,
+and all messages will be written to the terminal instead of syslog. If
+*chronyd* was compiled with enabled support for debugging, this option can be
+used twice to enable debug messages.
+
+*-l* _file_::
+This option enables writing of log messages to a file instead of syslog or the
+terminal.
+
+*-L* _level_::
+This option specifies the minimum severity level of messages to be written to
+the log file, syslog, or terminal. The following levels can be specified:
+0 (informational), 1 (warning), 2 (non-fatal error), and 3 (fatal error). The
+default value is 0.
+
+*-p*::
+When run in this mode, *chronyd* will print the configuration and exit. It will
+not detach from the terminal. This option can be used to verify the syntax of
+the configuration and get the whole configuration, even if it is split into
+multiple files and read by the *include* or *confdir* directive.
+
+*-q*::
+When run in this mode, *chronyd* will set the system clock once and exit. It
+will not detach from the terminal.
+
+*-Q*::
+This option is similar to the *-q* option, except it only prints the offset
+without making any corrections of the clock and it allows *chronyd* to be
+started without root privileges.
+
+*-r*::
+This option will try to reload and then delete files containing sample
+histories for each of the servers and reference clocks being used. The
+files are expected to be in the directory specified by the
+<<chrony.conf.adoc#dumpdir,*dumpdir*>>
+directive in the configuration file. This option is useful if you want to stop
+and restart *chronyd* briefly for any reason, e.g. to install a new version.
+However, it should be used only on systems where the kernel can maintain clock
+compensation whilst not under *chronyd*'s control (i.e. Linux, FreeBSD, NetBSD,
+illumos, and macOS 10.13 or later).
+
+*-R*::
+When this option is used, the <<chrony.conf.adoc#initstepslew,*initstepslew*>>
+directive and the <<chrony.conf.adoc#makestep,*makestep*>> directive used with
+a positive limit will be ignored. This option is useful when restarting
+*chronyd* and can be used in conjunction with the *-r* option.
+
+*-s*::
+This option will set the system clock from the computer's real-time clock (RTC)
+or to the last modification time of the file specified by the
+<<chrony.conf.adoc#driftfile,*driftfile*>> directive. Real-time clocks are
+supported only on Linux.
++
+If used in conjunction with the *-r* flag, *chronyd* will attempt to preserve
+the old samples after setting the system clock from the RTC. This can be used
+to allow *chronyd* to perform long term averaging of the gain or loss rate
+across system reboots, and is useful for systems with intermittent access to
+network that are shut down when not in use. For this to work well, it relies
+on *chronyd* having been able to determine accurate statistics for the
+difference between the RTC and system clock last time the computer was on.
++
+If the last modification time of the drift file is later than both the current
+time and the RTC time, the system time will be set to it to restore the time
+when *chronyd* was previously stopped. This is useful on computers that have no
+RTC or the RTC is broken (e.g. it has no battery).
+
+*-t* _timeout_::
+This option sets a timeout (in seconds) after which *chronyd* will exit. If the
+clock is not synchronised, it will exit with a non-zero status. This is useful
+with the *-q* or *-Q* option to shorten the maximum time waiting for
+measurements, or with the *-r* option to limit the time when *chronyd* is
+running, but still allow it to adjust the frequency of the system clock.
+
+*-u* _user_::
+This option sets the name of the system user to which *chronyd* will switch
+after start in order to drop root privileges. It overrides the
+<<chrony.conf.adoc#user,*user*>> directive. The compiled-in default value is
+_@DEFAULT_USER@_.
++
+On Linux, *chronyd* needs to be compiled with support for the *libcap* library.
+On macOS, FreeBSD, NetBSD, and illumos *chronyd* forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+
+*-U*::
+This option disables a check for root privileges to allow *chronyd* to be
+started under a non-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting *chronyd* under a non-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+
+*-F* _level_::
+This option configures system call filters loaded by *chronyd* processes if it
+was compiled with support for the Linux secure computing (seccomp) facility.
+Three levels are defined: 0, 1, 2. The filters are disabled at level 0. At
+levels 1 and 2, *chronyd* will be killed if it makes a system call which is
+blocked by the filters. The level can be specified as a negative number to
+trigger the SIGSYS signal instead of SIGKILL, which can be useful for
+debugging. The default value is 0.
++
+At level 1, the filters allow only selected system calls that are normally
+expected to be made by *chronyd*. Other system calls are blocked. This level is
+recommended only if it is known to work on the version of the system where
+*chrony* is installed. The filters need to allow also system calls made by
+libraries that *chronyd* is using (e.g. libc), but different versions or
+implementations of the libraries might make different system calls. If the
+filters are missing a system call, *chronyd* could be killed even in normal
+operation.
++
+At level 2, the filters block only a small number of specific system calls
+(e.g. fork and exec). This approach should avoid false positives, but the
+protection of the system against a compromised *chronyd* process is much more
+limited.
++
+The filters cannot be enabled with the *mailonchange* directive.
+
+*-P* _priority_::
+On Linux, FreeBSD, NetBSD, and illumos this option will select the SCHED_FIFO
+real-time scheduler at the specified priority (which must be between 0 and
+100). On macOS, this option must have either a value of 0 to disable the thread
+time constraint policy or 1 for the policy to be enabled. Other systems do not
+support this option. The default value is 0.
+
+*-m*::
+This option will lock *chronyd* into RAM so that it will never be paged out.
+This mode is only supported on Linux, FreeBSD, NetBSD, and illumos.
+
+*-x*::
+This option disables the control of the system clock. *chronyd* will not try to
+make any adjustments of the clock. It will assume the clock is free running and
+still track its offset and frequency relative to the estimated true time. This
+option allows *chronyd* to be started without the capability to adjust or set
+the system clock (e.g. in some containers) to operate as an NTP server.
+
+*-v*, *--version*::
+With this option *chronyd* will print version number to the terminal and exit.
+
+*-h*, *--help*::
+With this option *chronyd* will print a help message to the terminal and exit.
+
+== FILES
+
+_@SYSCONFDIR@/chrony.conf_
+
+== SEE ALSO
+
+<<chronyc.adoc#,*chronyc(1)*>>, <<chrony.conf.adoc#,*chrony.conf(5)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony.tuxfamily.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chronyd.man.in b/doc/chronyd.man.in
new file mode 100644
index 0000000..090d810
--- /dev/null
+++ b/doc/chronyd.man.in
@@ -0,0 +1,264 @@
+'\" t
+.\"     Title: chronyd
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.15
+.\"      Date: 2022-08-29
+.\"    Manual: System Administration
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONYD" "8" "2022-08-29" "chrony @CHRONY_VERSION@" "System Administration"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chronyd \- chrony daemon
+.SH "SYNOPSIS"
+.sp
+\fBchronyd\fP [\fIOPTION\fP]... [\fIDIRECTIVE\fP]...
+.SH "DESCRIPTION"
+.sp
+\fBchronyd\fP is a daemon for synchronisation of the system clock. It can
+synchronise the clock with NTP servers, reference clocks (e.g. a GPS receiver),
+and manual input using wristwatch and keyboard via \fBchronyc\fP. It can also
+operate as an NTPv4 (RFC 5905) server and peer to provide a time service to
+other computers in the network.
+.sp
+If no configuration directives are specified on the command line, \fBchronyd\fP
+will read them from a configuration file. The compiled\-in default location of
+the file is \fI@SYSCONFDIR@/chrony.conf\fP.
+.sp
+Informational messages, warnings, and errors will be logged to syslog.
+.SH "OPTIONS"
+.sp
+\fB\-4\fP
+.RS 4
+With this option hostnames will be resolved only to IPv4 addresses and only
+IPv4 sockets will be created.
+.RE
+.sp
+\fB\-6\fP
+.RS 4
+With this option hostnames will be resolved only to IPv6 addresses and only
+IPv6 sockets will be created.
+.RE
+.sp
+\fB\-f\fP \fIfile\fP
+.RS 4
+This option can be used to specify an alternate location for the configuration
+file. The compiled\-in default value is \fI@SYSCONFDIR@/chrony.conf\fP.
+.RE
+.sp
+\fB\-n\fP
+.RS 4
+When run in this mode, the program will not detach itself from the terminal.
+.RE
+.sp
+\fB\-d\fP
+.RS 4
+When run in this mode, the program will not detach itself from the terminal,
+and all messages will be written to the terminal instead of syslog. If
+\fBchronyd\fP was compiled with enabled support for debugging, this option can be
+used twice to enable debug messages.
+.RE
+.sp
+\fB\-l\fP \fIfile\fP
+.RS 4
+This option enables writing of log messages to a file instead of syslog or the
+terminal.
+.RE
+.sp
+\fB\-L\fP \fIlevel\fP
+.RS 4
+This option specifies the minimum severity level of messages to be written to
+the log file, syslog, or terminal. The following levels can be specified:
+0 (informational), 1 (warning), 2 (non\-fatal error), and 3 (fatal error). The
+default value is 0.
+.RE
+.sp
+\fB\-p\fP
+.RS 4
+When run in this mode, \fBchronyd\fP will print the configuration and exit. It will
+not detach from the terminal. This option can be used to verify the syntax of
+the configuration and get the whole configuration, even if it is split into
+multiple files and read by the \fBinclude\fP or \fBconfdir\fP directive.
+.RE
+.sp
+\fB\-q\fP
+.RS 4
+When run in this mode, \fBchronyd\fP will set the system clock once and exit. It
+will not detach from the terminal.
+.RE
+.sp
+\fB\-Q\fP
+.RS 4
+This option is similar to the \fB\-q\fP option, except it only prints the offset
+without making any corrections of the clock and it allows \fBchronyd\fP to be
+started without root privileges.
+.RE
+.sp
+\fB\-r\fP
+.RS 4
+This option will try to reload and then delete files containing sample
+histories for each of the servers and reference clocks being used. The
+files are expected to be in the directory specified by the
+\fBdumpdir\fP
+directive in the configuration file. This option is useful if you want to stop
+and restart \fBchronyd\fP briefly for any reason, e.g. to install a new version.
+However, it should be used only on systems where the kernel can maintain clock
+compensation whilst not under \fBchronyd\fP\(aqs control (i.e. Linux, FreeBSD, NetBSD,
+illumos, and macOS 10.13 or later).
+.RE
+.sp
+\fB\-R\fP
+.RS 4
+When this option is used, the \fBinitstepslew\fP
+directive and the \fBmakestep\fP directive used with
+a positive limit will be ignored. This option is useful when restarting
+\fBchronyd\fP and can be used in conjunction with the \fB\-r\fP option.
+.RE
+.sp
+\fB\-s\fP
+.RS 4
+This option will set the system clock from the computer\(cqs real\-time clock (RTC)
+or to the last modification time of the file specified by the
+\fBdriftfile\fP directive. Real\-time clocks are
+supported only on Linux.
+.sp
+If used in conjunction with the \fB\-r\fP flag, \fBchronyd\fP will attempt to preserve
+the old samples after setting the system clock from the RTC. This can be used
+to allow \fBchronyd\fP to perform long term averaging of the gain or loss rate
+across system reboots, and is useful for systems with intermittent access to
+network that are shut down when not in use. For this to work well, it relies
+on \fBchronyd\fP having been able to determine accurate statistics for the
+difference between the RTC and system clock last time the computer was on.
+.sp
+If the last modification time of the drift file is later than both the current
+time and the RTC time, the system time will be set to it to restore the time
+when \fBchronyd\fP was previously stopped. This is useful on computers that have no
+RTC or the RTC is broken (e.g. it has no battery).
+.RE
+.sp
+\fB\-t\fP \fItimeout\fP
+.RS 4
+This option sets a timeout (in seconds) after which \fBchronyd\fP will exit. If the
+clock is not synchronised, it will exit with a non\-zero status. This is useful
+with the \fB\-q\fP or \fB\-Q\fP option to shorten the maximum time waiting for
+measurements, or with the \fB\-r\fP option to limit the time when \fBchronyd\fP is
+running, but still allow it to adjust the frequency of the system clock.
+.RE
+.sp
+\fB\-u\fP \fIuser\fP
+.RS 4
+This option sets the name of the system user to which \fBchronyd\fP will switch
+after start in order to drop root privileges. It overrides the
+\fBuser\fP directive. The compiled\-in default value is
+\fI@DEFAULT_USER@\fP.
+.sp
+On Linux, \fBchronyd\fP needs to be compiled with support for the \fBlibcap\fP library.
+On macOS, FreeBSD, NetBSD, and illumos \fBchronyd\fP forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+.RE
+.sp
+\fB\-U\fP
+.RS 4
+This option disables a check for root privileges to allow \fBchronyd\fP to be
+started under a non\-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting \fBchronyd\fP under a non\-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+.RE
+.sp
+\fB\-F\fP \fIlevel\fP
+.RS 4
+This option configures system call filters loaded by \fBchronyd\fP processes if it
+was compiled with support for the Linux secure computing (seccomp) facility.
+Three levels are defined: 0, 1, 2. The filters are disabled at level 0. At
+levels 1 and 2, \fBchronyd\fP will be killed if it makes a system call which is
+blocked by the filters. The level can be specified as a negative number to
+trigger the SIGSYS signal instead of SIGKILL, which can be useful for
+debugging. The default value is 0.
+.sp
+At level 1, the filters allow only selected system calls that are normally
+expected to be made by \fBchronyd\fP. Other system calls are blocked. This level is
+recommended only if it is known to work on the version of the system where
+\fBchrony\fP is installed. The filters need to allow also system calls made by
+libraries that \fBchronyd\fP is using (e.g. libc), but different versions or
+implementations of the libraries might make different system calls. If the
+filters are missing a system call, \fBchronyd\fP could be killed even in normal
+operation.
+.sp
+At level 2, the filters block only a small number of specific system calls
+(e.g. fork and exec). This approach should avoid false positives, but the
+protection of the system against a compromised \fBchronyd\fP process is much more
+limited.
+.sp
+The filters cannot be enabled with the \fBmailonchange\fP directive.
+.RE
+.sp
+\fB\-P\fP \fIpriority\fP
+.RS 4
+On Linux, FreeBSD, NetBSD, and illumos this option will select the SCHED_FIFO
+real\-time scheduler at the specified priority (which must be between 0 and
+100). On macOS, this option must have either a value of 0 to disable the thread
+time constraint policy or 1 for the policy to be enabled. Other systems do not
+support this option. The default value is 0.
+.RE
+.sp
+\fB\-m\fP
+.RS 4
+This option will lock \fBchronyd\fP into RAM so that it will never be paged out.
+This mode is only supported on Linux, FreeBSD, NetBSD, and illumos.
+.RE
+.sp
+\fB\-x\fP
+.RS 4
+This option disables the control of the system clock. \fBchronyd\fP will not try to
+make any adjustments of the clock. It will assume the clock is free running and
+still track its offset and frequency relative to the estimated true time. This
+option allows \fBchronyd\fP to be started without the capability to adjust or set
+the system clock (e.g. in some containers) to operate as an NTP server.
+.RE
+.sp
+\fB\-v\fP, \fB\-\-version\fP
+.RS 4
+With this option \fBchronyd\fP will print version number to the terminal and exit.
+.RE
+.sp
+\fB\-h\fP, \fB\-\-help\fP
+.RS 4
+With this option \fBchronyd\fP will print a help message to the terminal and exit.
+.RE
+.SH "FILES"
+.sp
+\fI@SYSCONFDIR@/chrony.conf\fP
+.SH "SEE ALSO"
+.sp
+\fBchronyc(1)\fP, \fBchrony.conf(5)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony.tuxfamily.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/faq.adoc b/doc/faq.adoc
new file mode 100644
index 0000000..1b299d2
--- /dev/null
+++ b/doc/faq.adoc
@@ -0,0 +1,1049 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2014-2016, 2020-2022
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= Frequently Asked Questions
+:toc:
+:numbered:
+
+== `chrony` compared to other programs
+
+=== How does `chrony` compare to `ntpd`?
+
+`chrony` and `ntpd` are two different implementations of the Network Time
+Protocol (NTP).
+
+`chrony` is a newer implementation, which was designed to work well in a wider
+range of conditions. It can usually synchronise the system clock faster and
+with better time accuracy. It has many features, but it does not implement some
+of the less useful NTP modes like broadcast client or multicast server/client.
+
+If your computer is connected to the Internet only for few minutes at a time,
+the network connection is often congested, you turn your computer off or
+suspend it frequently, the clock is not very stable (e.g. there are rapid
+changes in the temperature or it is a virtual machine), or you want to use NTP
+on an isolated network with no hardware reference clocks in sight, `chrony`
+will probably work better for you.
+
+For a more detailed comparison of features and performance, see the
+https://chrony.tuxfamily.org/comparison.html[comparison page] on the `chrony`
+website.
+
+== Configuration issues
+
+=== What is the minimum recommended configuration for an NTP client?
+
+First, the client needs to know which NTP servers it should ask for the current
+time. They are specified by the `server` or `pool` directive. The `pool`
+directive is used with names that resolve to multiple addresses of different
+servers. For reliable operation, the client should have at least three servers.
+
+The `iburst` option enables a burst of requests to speed up the initial
+synchronisation.
+
+To stabilise the initial synchronisation on the next start, the estimated drift
+of the system clock is saved to a file specified by the `driftfile` directive.
+
+If the system clock can be far from the true time after boot for any reason,
+`chronyd` should be allowed to correct it quickly by stepping instead of
+slewing, which would take a very long time. The `makestep` directive does
+that.
+
+In order to keep the real-time clock (RTC) close to the true time, so the
+system time is reasonably close to the true time when it is initialised on the
+next boot from the RTC, the `rtcsync` directive enables a mode in which the
+system time is periodically copied to the RTC. It is supported on Linux and
+macOS.
+
+If you wanted to use public NTP servers from the
+https://www.pool.ntp.org/[pool.ntp.org] project, the minimal _chrony.conf_ file
+could be:
+
+----
+pool pool.ntp.org iburst
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+----
+
+=== How do I make an NTP server?
+
+By default, `chronyd` does not operate as an NTP server. You need to add an
+`allow` directive to the _chrony.conf_ file in order for `chronyd` to open the
+server NTP port and respond to client requests.
+
+----
+allow 192.168.1.0/24
+----
+
+An `allow` directive with no specified subnet allows access from all IPv4 and
+IPv6 addresses.
+
+=== Should all computers on a LAN be clients of an external server?
+
+It depends on the requirements. Usually, the best configuration is to make one
+computer the server, with the others as clients of it. Add a `local` directive
+to the server's _chrony.conf_ file. This configuration will be better because
+
+* the load on the external connection is less
+* the load on the external NTP server(s) is less
+* if your external connection goes down, the computers on the LAN
+  will maintain a common time with each other.
+
+=== Must I specify servers by IP address if DNS is not available on `chronyd` start?
+
+No, `chronyd` will keep trying to resolve
+the names specified by the `server`, `pool`, and `peer` directives in an
+increasing interval until it succeeds. The `online` command can be issued from
+`chronyc` to force `chronyd` to try to resolve the names immediately.
+
+=== How can I make `chronyd` more secure?
+
+If you do not need to use `chronyc`, or you want to run `chronyc` only
+under the root or _chrony_ user (which can access `chronyd` through a Unix
+domain socket), you can disable the IPv4 and IPv6 command sockets (by default
+listening on localhost) by adding `cmdport 0` to the configuration file.
+
+You can specify an unprivileged user with the `-u` option, or the `user`
+directive in the _chrony.conf_ file, to which `chronyd` will switch after start
+in order to drop root privileges. The configure script has a `--with-user`
+option, which sets the default user. On Linux, `chronyd` needs to be compiled
+with support for the `libcap` library. On other systems, `chronyd` forks into
+two processes. The child process retains root privileges, but can only perform
+a very limited range of privileged system calls on behalf of the parent.
+
+Also, if `chronyd` is compiled with support for the Linux secure computing
+(seccomp) facility, you can enable a system call filter with the `-F` option.
+It will significantly reduce the kernel attack surface and possibly prevent
+kernel exploits from the `chronyd` process if it is compromised. It is
+recommended to enable the filter only when it is known to work on the version of
+the system where `chrony` is installed as the filter needs to allow also system
+calls made from libraries that `chronyd` is using (e.g. libc) and different
+versions or implementations of the libraries might make different system calls.
+If the filter is missing some system call, `chronyd` could be killed even in
+normal operation.
+
+=== How can I make the system clock more secure?
+
+An NTP client synchronising the system clock to an NTP server is susceptible to
+various attacks, which can break applications and network protocols relying on
+accuracy of the clock (e.g. DNSSEC, Kerberos, TLS, WireGuard).
+
+Generally, a man-in-the-middle (MITM) attacker between the client and server
+can
+
+* make fake responses, or modify real responses from the server, to create an
+  arbitrarily large time and frequency offset, make the server appear more
+  accurate, insert a leap second, etc.
+* delay the requests and/or responses to create a limited time offset and
+  temporarily also a limited frequency offset
+* drop the requests or responses to prevent updates of the clock with new
+  measurements
+* redirect the requests to a different server
+
+The attacks can be combined for a greater effect. The attacker can delay
+packets to create a significant frequency offset first and then drop all
+subsequent packets to let the clock quickly drift away from the true time.
+The attacker might also be able to control the server's clock.
+
+Some attacks cannot be prevented. Monitoring is needed for detection, e.g. the
+reachability register in the `sources` report shows missing packets. The extent
+to which the attacker can control the client's clock depends on its
+configuration.
+
+Enable authentication to prevent `chronyd` from accepting modified, fake, or
+redirected packets. It can be enabled with a symmetric key specified by the
+`key` option, or Network Time Security (NTS) by the `nts` option (supported
+since `chrony` version 4.0). The server needs to support the selected
+authentication mechanism. Symmetric keys have to be configured on both client
+and server, and each client must have its own key (one per server).
+
+The maximum offset that the attacker can insert in an NTP measurement by
+delaying packets can be limited by the `maxdelay` option. The default value is
+3 seconds. The measured delay is reported as the peer delay in the `ntpdata`
+report and `measurements` log. Set the `maxdelay` option to a value larger than
+the maximum value that is normally observed. Note that the delay can increase
+significantly even when not under an attack, e.g. when the network is congested
+or the routing has changed.
+
+The maximum accepted change in time offset between clock updates can be limited
+by the `maxchange` directive. Larger changes in the offset will be ignored or
+cause `chronyd` to exit. Note that the attacker can get around this limit by
+splitting the offset into multiple smaller offsets and/or creating a large
+frequency offset. When this directive is used, `chronyd` will have to be
+restarted after a successful attack. It will not be able to recover on its own.
+It must not be restarted automatically (e.g. by the service manager).
+
+The impact of a large accepted time offset can be reduced by disabling clock
+steps, i.e. by not using the `makestep` and `initstepslew` directives. The
+offset will be slowly corrected by speeding up or slowing down the clock at a
+rate which can be limited by the `maxslewrate` directive. Disabling clock steps
+completely is practical only if the clock cannot gain a larger error on its
+own, e.g. when the computer is shut down or suspended, and the `maxslewrate`
+limit is large enough to correct an expected error in an acceptable time. The
+`rtcfile` directive with the `-s` option can be used to compensate for the RTC
+drift.
+
+A more practical approach is to enable `makestep` for a limited number of clock
+updates (the 2nd argument of the directive) and limit the offset change in all
+updates by the `maxchange` directive. The attacker will be able to make only a
+limited step and only if the attack starts in a short window after booting the
+computer, or when `chronyd` is restarted without the `-R` option.
+
+The frequency offset can be limited by the `maxdrift` directive. The measured
+frequency offset is reported in the drift file, `tracking` report, and
+`tracking` log. Set `maxdrift` to a value larger than the maximum absolute
+value that is normally observed. Note that the frequency of the clock can
+change due to aging of the crystal, differences in calibration of the clock
+source between reboots, migrated virtual machine, etc. A typical computer clock
+has a drift smaller than 100 parts per million (ppm), but much larger drifts
+are possible (e.g. in some virtual machines).
+
+Use only trusted servers, which you expect to be well configured and managed,
+using authentication for their own servers, etc. Use multiple servers, ideally
+in different locations. The attacker will have to deal with a majority of the
+servers in order to pass the source selection and update the clock with a large
+offset. Use the `minsources` directive to increase the required number of
+selectable sources to make the selection more robust.
+
+Do not specify servers as peers. The symmetric mode is less secure than the
+client/server mode. If not authenticated, it is vulnerable to off-path
+denial-of-service attacks, and even when it is authenticated, it is still
+susceptible to replay attacks.
+
+Mixing of authenticated and unauthenticated servers should generally be
+avoided. If mixing is necessary (e.g. for a more accurate and stable
+synchronisation to a closer server which does not support authentication), the
+authenticated servers should be configured as trusted and required to not allow
+the unauthenticated servers to override the authenticated servers in the source
+selection. Since `chrony` version 4.0, the selection options are enabled in
+such a case automatically. This behaviour can be disabled or modified by the
+`authselmode` directive.
+
+An example of a client configuration limiting the impact of the attacks could
+be
+
+----
+server foo.example.net iburst nts maxdelay 0.1
+server bar.example.net iburst nts maxdelay 0.2
+server baz.example.net iburst nts maxdelay 0.05
+server qux.example.net iburst nts maxdelay 0.1
+server quux.example.net iburst nts maxdelay 0.1
+minsources 3
+maxchange 100 0 0
+makestep 0.001 1
+maxdrift 100
+maxslewrate 100
+driftfile /var/lib/chrony/drift
+ntsdumpdir /var/lib/chrony
+rtcsync
+----
+
+=== How can I improve the accuracy of the system clock with NTP sources?
+
+Select NTP servers that are well synchronised, stable and close to your
+network. It is better to use more than one server. Three or four is usually
+recommended as the minimum, so `chronyd` can detect servers that serve false
+time and combine measurements from multiple sources.
+
+If you have a network card with hardware timestamping supported on Linux, it
+can be enabled by the `hwtimestamp` directive. It should make local receive and
+transmit timestamps of NTP packets much more stable and accurate.
+
+The `server` directive has some useful options: `minpoll`, `maxpoll`,
+`polltarget`, `maxdelay`, `maxdelayratio`, `maxdelaydevratio`, `xleave`,
+`filter`.
+
+The first three options set the minimum and maximum allowed polling interval,
+and how should be the actual interval adjusted in the specified range. Their
+default values are 6 (64 seconds) for `minpoll`, 10 (1024 seconds) for
+`maxpoll` and 8 (samples) for `polltarget`. The default values should be used
+for general servers on the Internet. With your own NTP servers, or if you have
+permission to poll some servers more frequently, setting these options for
+shorter polling intervals might significantly improve the accuracy of the
+system clock.
+
+The optimal polling interval depends mainly on two factors, stability of the
+network latency and stability of the system clock (which mainly depends on the
+temperature sensitivity of the crystal oscillator and the maximum rate of the
+temperature change).
+
+Generally, if the `sourcestats` command usually reports a small number of
+samples retained for a source (e.g. fewer than 16), a shorter polling interval
+should be considered. If the number of samples is usually at the maximum of 64,
+a longer polling interval might work better.
+
+An example of the directive for an NTP server on the Internet that you are
+allowed to poll frequently could be
+
+----
+server foo.example.net minpoll 4 maxpoll 6 polltarget 16
+----
+
+An example using shorter polling intervals with a server located in the same
+LAN could be
+
+----
+server ntp.local minpoll 2 maxpoll 4 polltarget 30
+----
+
+The maxdelay options are useful to ignore measurements with an unusually large
+delay (e.g. due to congestion in the network) and improve the stability of the
+synchronisation. The `maxdelaydevratio` option could be added to the example
+with local NTP server
+
+----
+server ntp.local minpoll 2 maxpoll 4 polltarget 30 maxdelaydevratio 2
+----
+
+If your server supports the interleaved mode (e.g. it is running `chronyd`),
+the `xleave` option should be added to the `server` directive to enable the
+server to provide the client with more accurate transmit timestamps (kernel or
+preferably hardware). For example:
+
+----
+server ntp.local minpoll 2 maxpoll 4 xleave
+----
+
+When combined with local hardware timestamping, good network switches, and even
+shorter polling intervals, a sub-microsecond accuracy and stability of a few
+tens of nanoseconds might be possible. For example:
+
+----
+server ntp.local minpoll 0 maxpoll 0 xleave
+hwtimestamp eth0
+----
+
+For best stability, the CPU should be running at a constant frequency (i.e.
+disabled power saving and performance boosting). Energy-Efficient Ethernet
+(EEE) should be disabled in the network. The switches should be configured to
+prioritize NTP packets, especially if the network is expected to be heavily
+loaded. The `dscp` directive can be used to set the Differentiated Services
+Code Point in transmitted NTP packets if needed.
+
+If it is acceptable for NTP clients in the network to send requests at a high
+rate, a sub-second polling interval can be specified. A median filter
+can be enabled in order to update the clock at a reduced rate with more stable
+measurements. For example:
+
+----
+server ntp.local minpoll -6 maxpoll -6 filter 15 xleave
+hwtimestamp eth0 minpoll -6
+----
+
+Since `chrony` version 4.3, the minimum `minpoll` is -7 and a filter using a
+long-term estimate of a delay quantile can be enabled by the `maxdelayquant`
+option to replace the default `maxdelaydevratio` filter, which is sensitive to
+outliers corrupting the minimum delay. For example:
+
+----
+server ntp.local minpoll -7 maxpoll -7 filter 31 maxdelayquant 0.3 xleave
+----
+
+As an experimental feature added in version 4.2, `chronyd` supports an NTPv4
+extension field containing an additional timestamp to enable frequency transfer
+and significantly improve stability of synchronisation. It can be enabled by
+the `extfield F323` option. For example:
+
+----
+server ntp.local minpoll 0 maxpoll 0 xleave extfield F323
+----
+
+=== Does `chronyd` have an ntpdate mode?
+
+Yes. With the `-q` option `chronyd` will set the system clock once and exit.
+With the `-Q` option it will print the measured offset without setting the
+clock. If you do not want to use a configuration file, NTP servers can be
+specified on the command line. For example:
+
+----
+# chronyd -q 'pool pool.ntp.org iburst'
+----
+
+The command above would normally take about 5 seconds if the servers were
+well synchronised and responding to all requests. If not synchronised or
+responding, it would take about 10 seconds for `chronyd` to give up and exit
+with a non-zero status. A faster configuration is possible. A single server can
+be used instead of four servers, the number of measurements can be reduced with
+the `maxsamples` option to one (supported since `chrony` version 4.0), and a
+timeout can be specified with the `-t` option. The following command would take
+only up to about one second.
+
+----
+# chronyd -q -t 1 'server pool.ntp.org iburst maxsamples 1'
+----
+
+It is not recommended to run `chronyd` with the `-q` option periodically (e.g.
+from a cron job) as a replacement for the daemon mode, because it performs
+significantly worse (e.g. the clock is stepped and its frequency is not
+corrected). If you must run it this way and you are using a public NTP server,
+make sure `chronyd` does not always start around the first second of a minute,
+e.g. by adding a random sleep before the `chronyd` command. Public servers
+typically receive large bursts of requests around the first second as there is
+a large number of NTP clients started from cron with no delay.
+
+=== Can `chronyd` be configured to control the clock like `ntpd`?
+
+It is not possible to perfectly emulate `ntpd`, but there are some options that
+can configure `chronyd` to behave more like `ntpd` if there is a reason to
+prefer that.
+
+In the following example the `minsamples` directive slows down the response to
+changes in the frequency and offset of the clock. The `maxslewrate` and
+`corrtimeratio` directives reduce the maximum frequency error due to an offset
+correction and the `maxdrift` directive reduces the maximum assumed frequency
+error of the clock. The `makestep` directive enables a step threshold and the
+`maxchange` directive enables a panic threshold. The `maxclockerror` directive
+increases the minimum dispersion rate.
+
+----
+minsamples 32
+maxslewrate 500
+corrtimeratio 100
+maxdrift 500
+makestep 0.128 -1
+maxchange 1000 1 1
+maxclockerror 15
+----
+
+Note that increasing `minsamples` might cause the offsets in the `tracking` and
+`sourcestats` reports/logs to be significantly smaller than the actual offsets
+and be unsuitable for monitoring.
+
+=== Can NTP server be separated from NTP client?
+
+Yes, it is possible to run multiple instances of `chronyd` on a computer at the
+same time. One can operate primarily as an NTP client to synchronise the system
+clock and another as a server for other computers. If they use the same
+filesystem, they need to be configured with different pidfiles, Unix domain
+command sockets, and any other file or directory specified in the configuration
+file. If they run in the same network namespace, they need to use different NTP
+and command ports, or bind the ports to different addresses or interfaces.
+
+The server instance should be started with the `-x` option to prevent it from
+adjusting the system clock and interfering with the client instance. It can be
+configured as a client to synchronise its NTP clock to other servers, or the
+client instance running on the same computer. In the latter case, the `copy`
+option (added in `chrony` version 4.1) can be used to assume the reference ID
+and stratum of the client instance, which enables detection of synchronisation
+loops with its own clients.
+
+On Linux, starting with `chrony` version 4.0, it is possible to run multiple
+server instances sharing a port to better utilise multiple cores of the CPU.
+Note that for rate limiting and client/server interleaved mode to work well
+it is necessary that all packets received from the same address are handled by
+the same server instance.
+
+An example configuration of the client instance could be
+
+----
+pool pool.ntp.org iburst
+allow 127.0.0.1
+port 11123
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+----
+
+and configuration of the first server instance could be
+
+----
+server 127.0.0.1 port 11123 minpoll 0 maxpoll 0 copy
+allow
+cmdport 11323
+bindcmdaddress /var/run/chrony/chronyd-server1.sock
+pidfile /var/run/chronyd-server1.pid
+driftfile /var/lib/chrony/drift-server1
+----
+
+=== Should be a leap smear enabled on NTP server?
+
+With the `smoothtime` and `leapsecmode` directives it is possible to enable a
+server leap smear in order to hide leap seconds from clients and force them to
+follow a slow server's adjustment instead.
+
+This feature should be used only in local networks and only when necessary,
+e.g. when the clients cannot be configured to handle the leap seconds as
+needed, or their number is so large that configuring them all would be
+impractical. The clients should use only one leap-smearing server, or multiple
+identically configured leap-smearing servers. Note that some clients can get
+leap seconds from other sources (e.g. with the `leapsectz` directive in
+`chrony`) and they will not work correctly with a leap smearing server.
+
+=== How should `chronyd` be configuration with `gpsd`?
+
+A GPS or other GNSS receiver can be used as a reference clock with `gpsd`. It
+can work as one or two separate time sources for each connected receiver. The
+first time source is based on timestamping of messages sent by the receiver.
+Typically, it is accurate to milliseconds. The other source is much more
+accurate. It is timestamping a pulse-per-second (PPS) signal, usually connected
+to a serial port (e.g. DCD pin) or GPIO pin.
+
+If the PPS signal is connected to the serial port which is receiving messages
+from the GPS/GNSS receiver, `gpsd` should detect and use it automatically. If
+it is connected to a GPIO pin, or another serial port, the PPS device needs to
+be specified on the command line as an additional data source. On Linux, the
+`ldattach` utility can be used to create a PPS device for a serial device.
+
+The message-based time source provided by `gpsd` is specified as a `SHM 0`
+refclock, or other even number if `gpsd` is configured with multiple receivers.
+
+The PPS-based time source is specified as a `SHM 1` refclock (or other odd
+number), or `SOCK /var/run/chrony.DEV.sock` where `DEV` is the name of the
+serial device (e.g. ttyS0).
+
+With `chronyd` and `gpsd` both supporting PPS, and `gpsd` providing two
+different refclocks for PPS, there are three different recommended
+configurations:
+
+----
+# First option
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS
+
+# Second option
+refclock SHM 1 refid GPS
+
+# Third option
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SHM 0 offset 0.5 delay 0.1 refid NMEA noselect
+----
+
+Each option has some advantages:
+
+* `SOCK` does not use polling (i.e. it can get samples earlier than `SHM`),
+  but it requires `gpsd` to be started after `chronyd` in order to connect to
+  its socket
+* `SOCK` and `SHM 1` can be more accurate than `PPS` if `gpsd` corrects for the
+  sawtooth error provided by the receiver in serial data
+* `PPS` can be used with higher PPS rates (specified by the `rate` option),
+  but it requires a second refclock or another time source to pair pulses
+  with seconds, and the `SHM 0` offset needs to be specified
+  <<using-pps-refclock,correctly>> to compensate for the message delay, while
+  `gpsd` can apply HW-specific information
+
+If the PPS signal is not available, or cannot be used for some reason, the only
+option is the message-based timing
+
+----
+refclock SHM 0 offset 0.5 delay 0.1 refid GPS
+----
+
+=== Does `chrony` support PTP?
+
+No, the Precision Time Protocol (PTP) is not supported as a protocol for
+synchronisation of clocks and there are no plans
+to support it. It is a complex protocol, which shares some issues with the
+NTP broadcast mode. One of the main differences between NTP and PTP is that PTP
+was designed to be easily supported in hardware (e.g. network switches and
+routers) in order to make more stable and accurate measurements. PTP relies on
+the hardware support. NTP does not rely on any support in the hardware, but if
+it had the same support as PTP, it could perform equally well.
+
+On Linux, `chrony` supports hardware clocks that some NICs have for PTP. They
+are called PTP hardware clocks (PHC). They can be used as reference clocks
+(specified by the `refclock` directive) and for hardware timestamping of NTP
+packets (enabled by the `hwtimestamp` directive) if the NIC can timestamp other
+packets than PTP, which is usually the case at least for transmitted packets.
+The `ethtool -T` command can be used to verify the timestamping support.
+
+As an experimental feature added in version 4.2, `chrony` can use PTP as a
+transport for NTP messages (NTP over PTP) to enable hardware timestamping on
+hardware which can timestamp PTP packets only. It can be enabled by the
+`ptpport` directive.
+
+=== Why are client log records dropped before reaching `clientloglimit`?
+
+The number of dropped client log records reported by the `serverstats` command
+can be increasing before the number of clients reported by the `clients` command
+reaches the maximum value corresponding to the memory limit set by the
+`clientloglimit` directive.
+
+This is due to the design of the data structure keeping the client records. It
+is a hash table which can store only up to 16 colliding addresses per slot. If
+a slot has more collisions and the table already has the maximum size, the
+oldest record will be dropped and replaced by the new client.
+
+Note that the size of the table is always a power of two and it can only grow.
+The limit set by the `clientloglimit` directive takes into account that two
+copies of the table exist when it is being resized. This means the actual
+memory usage reported by `top` and other utilities can be significantly smaller
+than the limit even when the maximum number of records is used.
+
+The absolute maximum number of client records kept at the same time is
+16777216.
+
+=== What happened to the `commandkey` and `generatecommandkey` directives?
+
+They were removed in version 2.2. Authentication is no longer supported in the
+command protocol. Commands that required authentication are now allowed only
+through a Unix domain socket, which is accessible only by the root and _chrony_
+users. If you need to configure `chronyd` remotely or locally without the root
+password, please consider using ssh and/or sudo to run `chronyc` under the root
+or _chrony_ user on the host where `chronyd` is running.
+
+== Computer is not synchronising
+
+This is the most common problem. There are a number of reasons, see the
+following questions.
+
+=== Behind a firewall?
+
+Check the `Reach` value printed by the ``chronyc``'s `sources` command. If it
+is zero, it means `chronyd` did not get any valid responses from the NTP server
+you are trying to use. If there is a firewall between you and the server, the
+packets might be blocked. Try using a tool like `wireshark` or `tcpdump` to see
+if you are getting any responses from the server.
+
+When `chronyd` is receiving responses from the servers, the output of the
+`sources` command issued few minutes after `chronyd` start might look like
+this:
+
+----
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+^* foo.example.net               2   6   377    34   +484us[ -157us] +/-   30ms
+^- bar.example.net               2   6   377    34    +33ms[  +32ms] +/-   47ms
+^+ baz.example.net               3   6   377    35  -1397us[-2033us] +/-   60ms
+----
+
+=== Are NTP servers specified with the `offline` option?
+
+Check that the ``chronyc``'s `online` and `offline` commands are used
+appropriately (e.g. in the system networking scripts). The `activity` command
+prints the number of sources that are currently online and offline. For
+example:
+
+----
+200 OK
+3 sources online
+0 sources offline
+0 sources doing burst (return to online)
+0 sources doing burst (return to offline)
+0 sources with unknown address
+----
+
+=== Is name resolution working correctly?
+
+NTP servers specified by their hostname (instead of an IP address) have to have
+their names resolved before `chronyd` can send any requests to them. If the
+`activity` command prints a non-zero number of sources with unknown address,
+there is an issue with the resolution. Typically, a DNS server is specified in
+_/etc/resolv.conf_. Make sure it is working correctly.
+
+Since `chrony` version 4.0, you can run `chronyc -N sources -a` command to
+print all sources, even those that do not have a known address yet, with their
+names as they were specified in the configuration. This can be useful to verify
+that the names specified in the configuration are used as expected.
+
+=== Is `chronyd` allowed to step the system clock?
+
+By default, `chronyd` adjusts the clock gradually by slowing it down or
+speeding it up. If the clock is too far from the true time, it will take
+a long time to correct the error. The `System time` value printed by the
+``chronyc``'s `tracking` command is the remaining correction that needs to be
+applied to the system clock.
+
+The `makestep` directive can be used to allow `chronyd` to step the clock. For
+example, if _chrony.conf_ had
+
+----
+makestep 1 3
+----
+
+the clock would be stepped in the first three updates if its offset was larger
+than one second. Normally, it is recommended to allow the step only in the first
+few updates, but in some cases (e.g. a computer without an RTC or virtual
+machine which can be suspended and resumed with an incorrect time) it might be
+necessary to allow the step on any clock update. The example above would change
+to
+
+----
+makestep 1 -1
+----
+
+=== Using NTS?
+
+The Network Time Security (NTS) mechanism uses Transport Layer Security (TLS)
+to establish the keys needed for authentication of NTP packets.
+
+Run the `authdata` command to check whether the key establishment was
+successful:
+
+----
+# chronyc -N authdata
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256  33m    0    0    8  100
+bar.example.net              NTS     1   15  256  33m    0    0    8  100
+baz.example.net              NTS     1   15  256  33m    0    0    8  100
+----
+
+The KeyID, Type, and KLen columns should have non-zero values. If they are
+zero, check the system log for error messages from `chronyd`. One possible
+cause of failure is a firewall blocking the client's connection to the server's
+TCP port 4460.
+
+Another possible cause of failure is a certificate that is failing to verify
+because the client's clock is wrong. This is a chicken-and-egg problem with NTS.
+You might need to manually correct the date, or temporarily disable NTS, in
+order to get NTS working. If your computer has an RTC and it is backed up by a
+good battery, this operation should be needed only once, assuming the RTC will
+be set periodically with the `rtcsync` directive, or compensated with the
+`rtcfile` directive and the `-s` option.
+
+If the computer does not have an RTC or battery, you can use the `-s` option
+without `rtcfile` directive to restore time of the last shutdown or reboot from
+the drift file. The clock will start behind the true time, but if the computer
+was not shut down for too long and the server's certificate was not renewed too
+close to its expiration, it should be sufficient for the time checks to
+succeed.
+
+If you run your own server, you can use a self-signed certificate covering
+all dates where the client can start (e.g. years 1970-2100). The certificate
+needs to be installed on the client and specified with the `ntstrustedcerts`
+directive. The server can have multiple names and certificates. To avoid
+trusting a certificate for too long, a new certificate can be added to the
+server periodically (e.g. once per year) and the client can have the server
+name and trusted certificate updated automatically (e.g. using a package
+repository, or a cron script downloading the files directly from the server
+over HTTPS). A client that was shut down for years will still be able to
+synchronise its clock and perform the update as long as the server keeps
+the old certificate.
+
+As a last resort, you can disable the time checks by the `nocerttimecheck`
+directive. This has some important security implications. To reduce the
+security risk, you can use the `nosystemcert` and `ntstrustedcerts` directives
+to disable the system's default trusted certificate authorities and trust only
+a minimal set of selected authorities needed to validate the certificates of
+used NTP servers.
+
+=== Using a Windows NTP server?
+
+A common issue with Windows NTP servers is that they report a very large root
+dispersion (e.g. three seconds or more), which causes `chronyd` to ignore the
+server for being too inaccurate. The `sources` command might show a valid
+measurement, but the server is not selected for synchronisation. You can check
+the root dispersion of the server with the ``chronyc``'s `ntpdata` command.
+
+The `maxdistance` value needs to be increased in _chrony.conf_ to enable
+synchronisation to such a server. For example:
+
+----
+maxdistance 16.0
+----
+
+=== An unreachable source is selected?
+
+When `chronyd` is configured with multiple time sources, it tries to select the
+most accurate and stable sources for synchronisation of the system clock. They
+are marked with the _*_ or _+_ symbol in the report printed by the `sources`
+command.
+
+When the best source (marked with the _*_ symbol) becomes unreachable (e.g. NTP
+server stops responding), `chronyd` will not immediately switch
+to the second best source in an attempt to minimise the error of the clock. It
+will let the clock run free for as long as its estimated error (in terms of
+root distance) based on previous measurements is smaller than the estimated
+error of the second source, and there is still an interval which contains some
+measurements from both sources.
+
+If the first source was significantly better than the second source, it can
+take many hours before the second source is selected, depending on its polling
+interval. You can force a faster reselection by increasing the clock error rate
+(`maxclockerror` directive), shortening the polling interval (`maxpoll`
+option), or reducing the number of samples (`maxsamples` option).
+
+=== Does selected source drop new measurements?
+
+`chronyd` can drop a large number of successive NTP measurements if they are
+not passing some of the NTP tests. The `sources` command can report for a
+selected source the fully-reachable value of 377 in the Reach column and at the
+same time a LastRx value that is much larger than the current polling interval.
+If the source is online, this indicates that a number of measurements was
+dropped. You can use the `ntpdata` command to check the NTP tests for the last
+measurement. Usually, it is the test C which fails.
+
+This can be an issue when there is a long-lasting increase in the measured
+delay, e.g. due to a routing change in the network. Unfortunately, `chronyd`
+does not know for how long it should wait for the delay to come back to the
+original values, or whether it is a permanent increase and it should start from
+scratch.
+
+The test C is an adaptive filter. It can take many hours before it accepts
+a measurement with the larger delay, and even much longer before it drops all
+measurements with smaller delay, which determine an expected delay used by the
+test. You can use the `reset sources` command to drop all measurements
+immediately (available in chrony 4.0 and later). If this issue happens
+frequently, you can effectively disable the test by setting the
+`maxdelaydevratio` option to a very large value (e.g. 1000000), or speed up the
+recovery by increasing the clock error rate with the `maxclockerror` directive.
+
+[[using-pps-refclock]]
+=== Using a PPS reference clock?
+
+A pulse-per-second (PPS) reference clock requires a non-PPS time source to
+determine which second of UTC corresponds to each pulse. If it is another
+reference clock specified with the `lock` option in the `refclock` directive,
+the offset between the two reference clocks must be smaller than 0.4 seconds
+(0.2 seconds with `chrony` versions before 4.1) in
+order for the PPS reference clock to work. With NMEA reference clocks it is
+common to have a larger offset. It needs to be corrected with the `offset`
+option.
+
+One approach to find out a good value of the `offset` option is to configure
+the reference clocks with the `noselect` option and compare them to an NTP
+server. For example, if the `sourcestats` command showed
+
+----
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+PPS0                        0   0     0     +0.000   2000.000     +0ns  4000ms
+NMEA                       58  30   231    -96.494     38.406   +504ms  6080us
+foo.example.net             7   3   200     -2.991     16.141   -107us   492us
+----
+
+the offset of the NMEA source would need to be increased by about 0.504
+seconds. It does not have to be very accurate. As long as the offset of the
+NMEA reference clock stays below the limit, the PPS reference clock should be
+able to determine the seconds corresponding to the pulses and allow the samples
+to be used for synchronisation.
+
+== Issues with `chronyc`
+
+=== I keep getting the error `506 Cannot talk to daemon`
+
+When accessing `chronyd` remotely, make sure that the _chrony.conf_ file (on
+the computer where `chronyd` is running) has a `cmdallow` entry for the
+computer you are running `chronyc` on and an appropriate `bindcmdaddress`
+directive. This is not necessary for localhost.
+
+Perhaps `chronyd` is not running. Try using the `ps` command (e.g. on Linux,
+`ps -auxw`) to see if it is running. Or try `netstat -a` and see if the UDP
+port 323 is listening. If `chronyd` is not running, you might have a problem
+with the way you are trying to start it (e.g. at boot time).
+
+Perhaps you have a firewall set up in a way that blocks packets on the UDP
+port 323. You need to amend the firewall configuration in this case.
+
+=== I keep getting the error `501 Not authorised`
+
+This error indicates that `chronyc` sent the command to `chronyd` using a UDP
+socket instead of the Unix domain socket (e.g. _/var/run/chrony/chronyd.sock_),
+which is required for some commands. For security reasons, only the root and
+_chrony_ users are allowed to access the socket.
+
+It is also possible that the socket does not exist. `chronyd` will not create
+the socket if the directory has a wrong owner or permissions. In this case
+there should be an error message from `chronyd` in the system log.
+
+=== What is the reference ID reported by the `tracking` command?
+
+The reference ID is a 32-bit value used in NTP to prevent synchronisation
+loops.
+
+In `chrony` versions before 3.0 it was printed in the
+quad-dotted notation, even if the reference source did not actually have an
+IPv4 address. For IPv4 addresses, the reference ID is equal to the address, but
+for IPv6 addresses it is the first 32 bits of the MD5 sum of the address. For
+reference clocks, the reference ID is the value specified with the `refid`
+option in the `refclock` directive.
+
+Since version 3.0, the reference ID is printed as a hexadecimal number to avoid
+confusion with IPv4 addresses.
+
+If you need to get the IP address of the current reference source, use the `-n`
+option to disable resolving of IP addresses and read the second field (printed
+in parentheses) on the `Reference ID` line.
+
+=== Is the `chronyc` / `chronyd` protocol documented anywhere?
+
+Only by the source code. See _cmdmon.c_ (`chronyd` side) and _client.c_
+(`chronyc` side).
+
+Note that this protocol is not compatible with the mode 6 or mode 7 protocol
+supported by `ntpd`, i.e. the `ntpq` or `ntpdc` utility cannot be used to
+monitor `chronyd`, and `chronyc` cannot be used to monitor `ntpd`.
+
+== Real-time clock issues
+
+=== What is the real-time clock (RTC)?
+
+This is the clock which keeps the time even when your computer is turned off.
+It is used to initialise the system clock on boot. It normally does not drift
+more than few seconds per day.
+
+There are two approaches how `chronyd` can work with it. One is to use the
+`rtcsync` directive, which tells `chronyd` to enable a kernel mode which sets
+the RTC from the system clock every 11 minutes. `chronyd` itself will not touch
+the RTC. If the computer is not turned off for a long time, the RTC should
+still be close to the true time when the system clock will be initialised from
+it on the next boot.
+
+The other option is to use the `rtcfile` directive, which tells `chronyd` to
+monitor the rate at which the RTC gains or loses time. When `chronyd` is
+started with the `-s` option on the next boot, it will set the system time from
+the RTC and also compensate for the drift it has measured previously. The
+`rtcautotrim` directive can be used to keep the RTC close to the true time, but
+it is not strictly necessary if its only purpose is to set the system clock when
+`chronyd` is started on boot. See the documentation for details.
+
+=== Does `hwclock` have to be disabled?
+
+The `hwclock` program is run by default in the boot and/or shutdown
+scripts in some Linux installations. With the kernel RTC synchronisation
+(`rtcsync` directive), the RTC will be set also every 11 minutes as long as the
+system clock is synchronised. If you want to use ``chronyd``'s RTC monitoring
+(`rtcfile` directive), it is important to disable `hwclock` in the shutdown
+procedure. If you do not do that, it will overwrite the RTC with a new value, unknown
+to `chronyd`. At the next reboot, `chronyd` started with the `-s` option will
+compensate this (wrong) time with its estimate of how far the RTC has drifted
+whilst the power was off, giving a meaningless initial system time.
+
+There is no need to remove `hwclock` from the boot process, as long as `chronyd`
+is started after it has run.
+
+=== I just keep getting the `513 RTC driver not running` message
+
+For the real-time clock support to work, you need the following three
+things
+
+* an RTC in your computer
+* a Linux kernel with enabled RTC support
+* an `rtcfile` directive in your _chrony.conf_ file
+
+=== I get `Could not open /dev/rtc, Device or resource busy` in my syslog file
+
+Some other program running on the system might be using the device.
+
+=== When I start `chronyd`, the log says `Could not enable RTC interrupt : Invalid argument` (or it may say `disable`)
+
+Your real-time clock hardware might not support the required ioctl requests:
+
+* `RTC_UIE_ON`
+* `RTC_UIE_OFF`
+
+A possible solution could be to build the Linux kernel with support for software
+emulation instead; try enabling the following configuration option when building
+the Linux kernel:
+
+* `CONFIG_RTC_INTF_DEV_UIE_EMUL`
+
+=== What if my computer does not have an RTC or backup battery?
+
+In this case you can still use the `-s` option to set the system clock to the
+last modification time of the drift file, which should correspond to the system
+time when `chronyd` was previously stopped. The initial system time will be
+increasing across reboots and applications started after `chronyd` will not
+observe backward steps.
+
+== NTP-specific issues
+
+=== Can `chronyd` be driven from broadcast/multicast NTP servers?
+
+No, the broadcast/multicast client mode is not supported and there is currently
+no plan to implement it. While this mode can simplify configuration
+of clients in large networks, it is inherently less accurate and less secure
+(even with authentication) than the ordinary client/server mode.
+
+When configuring a large number of clients in a network, it is recommended to
+use the `pool` directive with a DNS name which resolves to addresses of
+multiple NTP servers. The clients will automatically replace the servers when
+they become unreachable, or otherwise unsuitable for synchronisation, with new
+servers from the pool.
+
+Even with very modest hardware, an NTP server can serve time to hundreds of
+thousands of clients using the ordinary client/server mode.
+
+=== Can `chronyd` transmit broadcast NTP packets?
+
+Yes, the `broadcast` directive can be used to enable the broadcast server mode
+to serve time to clients in the network which support the broadcast client mode
+(it is not supported in `chronyd`). Note that this mode should generally be
+avoided. See the previous question.
+
+=== Can `chronyd` keep the system clock a fixed offset away from real time?
+
+Yes. Starting from version 3.0, an offset can be specified by the `offset`
+option for all time sources in the _chrony.conf_ file.
+
+=== What happens if the network connection is dropped without using ``chronyc``'s `offline` command first?
+
+`chronyd` will keep trying to access the sources that it thinks are online, and
+it will take longer before new measurements are actually made and the clock is
+corrected when the network is connected again. If the sources were set to
+offline, `chronyd` would make new measurements immediately after issuing the
+`online` command.
+
+Unless the network connection lasts only few minutes (less than the maximum
+polling interval), the delay is usually not a problem, and it might be acceptable
+to keep all sources online all the time.
+
+=== Why is an offset measured between two computers synchronised to each another?
+
+When two computers are synchronised to each other using the client/server or
+symmetric NTP mode, there is an expectation that NTP measurements between the
+two computers made on both ends show an average offset close to zero.
+
+With `chronyd` that can be expected only when the interleaved mode is enabled
+by the `xleave` option. Otherwise, `chronyd` will use different transmit
+timestamps (e.g. daemon timestamp vs kernel timestamp) for serving time and
+synchronisation of its own clock, which will cause the other computer to
+measure a significant offset.
+
+== Operation
+
+=== What clocks does `chronyd` use?
+
+There are several different clocks used by `chronyd`:
+
+* *System clock:* software clock maintained by the kernel. It is the main clock
+  used by applications running on the computer. It is synchronised by `chronyd`
+  to its NTP clock, unless started with the *-x* option.
+* *NTP clock:* software clock (virtual) based on the system clock and internal
+  to `chronyd`. It keeps the best estimate of the true time according to the
+  configured time sources, which is served to NTP clients unless time smoothing
+  is enabled by the *smoothtime* directive. The *System time* value in the
+  `tracking` report is the current offset between the system and NTP clock.
+* *Real-time clock (RTC):* hardware clock keeping time even when the
+  computer is turned off. It is used by the kernel to initialise the system
+  clock on boot and also by `chronyd` to compensate for its measured drift if
+  configured with the `rtcfile` directive and started with the `-s` option.
+  The clock can be kept accurate only by stepping enabled by the `rtcsync` or
+  `rtcautotrim` directive.
+* *Reference clock:* hardware clock used as a time source. It is specified by
+  the `refclock` directive.
+* *NIC clock (also known as PTP hardware clock):* hardware clock timestamping
+  packets received and transmitted by a network device specified by the
+  *hwtimestamp* directive. The clock is expected to be running free. It is not
+  synchronised by `chronyd`. Its offset is tracked relative to the NTP clock in
+  order to convert the hardware timestamps.
+
+== Operating systems
+
+=== Does `chrony` support Windows?
+
+No. The `chronyc` program (the command-line client used for configuring
+`chronyd` while it is running) has been successfully built and run under
+Cygwin in the past. `chronyd` is not portable, because part of it is
+very system-dependent. It needs adapting to work with Windows'
+equivalent of the adjtimex() call, and it needs to be made to work as a
+service.
+
+=== Are there any plans to support Windows?
+
+We have no plans to do this. Anyone is welcome to pick this work up and
+contribute it back to the project.
diff --git a/doc/installation.adoc b/doc/installation.adoc
new file mode 100644
index 0000000..b683911
--- /dev/null
+++ b/doc/installation.adoc
@@ -0,0 +1,200 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2009-2016
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= Installation
+
+The software is distributed as source code which has to be compiled. The source
+code is supplied in the form of a gzipped tar file, which unpacks to a
+subdirectory identifying the name and version of the program.
+
+A C compiler (e.g. `gcc` or `clang`) and GNU Make are needed to build `chrony`.
+The following libraries with their development files, and programs, are needed
+to enable optional features:
+
+* pkg-config: detection of development libraries
+* Nettle, GnuTLS, NSS, or LibTomCrypt: secure hash functions (`SECHASH`)
+* libcap: dropping root privileges on Linux (`DROPROOT`)
+* libseccomp: system call filter on Linux (`SCFILTER`)
+* GnuTLS and Nettle: Network Time Security (`NTS`)
+* Editline: line editing in `chronyc` (`READLINE`)
+* timepps.h header: PPS reference clock
+* Asciidoctor: documentation in HTML format
+* Bash: test suite
+
+The following programs are needed when building `chrony` from the git
+repository instead of a released tar file:
+
+* Asciidoctor: manual pages
+* Bison: parser for chronyc settime command
+
+After unpacking the source code, change directory into it, and type
+
+----
+./configure
+----
+
+This is a shell script that automatically determines the system type. There is
+an optional parameter `--prefix`, which indicates the directory tree where the
+software should be installed. For example,
+
+----
+./configure --prefix=/opt/free
+----
+
+will install the `chronyd` daemon into `/opt/free/sbin` and the `chronyc`
+control program into `/opt/free/bin`. The default value for the prefix is
+`/usr/local`.
+
+The `configure` script assumes you want to use `gcc` as your compiler. If you
+want to use a different compiler, you can configure this way:
+
+----
+CC=cc ./configure --prefix=/opt/free
+----
+
+for Bourne-family shells, or
+
+----
+setenv CC cc
+setenv CFLAGS -O
+./configure --prefix=/opt/free
+----
+
+for C-family shells.
+
+If the software cannot (yet) be built on your system, an error message will be
+shown. Otherwise, `Makefile` will be generated.
+
+On Linux, if development files for the libcap library are available, `chronyd`
+will be built with support for dropping root privileges. On other systems no
+extra library is needed. The default user which `chronyd` should run as can be
+specified with the `--with-user` option of the `configure` script.
+
+If development files for the POSIX threads library are available, `chronyd`
+will be built with support for asynchronous resolving of hostnames specified in
+the `server`, `peer`, and `pool` directives. This allows `chronyd` operating as
+a server to respond to client requests when resolving a hostname. If you don't
+want to enable the support, specify the `--disable-asyncdns` flag to
+`configure`.
+
+If development files for the https://www.lysator.liu.se/~nisse/nettle/[Nettle],
+https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS[NSS], or
+https://www.libtom.net/LibTomCrypt/[libtomcrypt] library are available,
+`chronyd` will be built with support for other cryptographic hash functions
+than MD5, which can be used for NTP authentication with a symmetric key. If you
+don't want to enable the support, specify the `--disable-sechash` flag to
+`configure`.
+
+If development files for the editline library are available,
+`chronyc` will be built with line editing support. If you don't want this,
+specify the `--disable-readline` flag to `configure`.
+
+If a `timepps.h` header is available (e.g. from the
+http://linuxpps.org[LinuxPPS project]), `chronyd` will be built with PPS API
+reference clock driver. If the header is installed in a location that isn't
+normally searched by the compiler, you can add it to the searched locations by
+setting the `CPPFLAGS` variable to `-I/path/to/timepps`.
+
+The `--help` option can be specified to `configure` to print all options
+supported by the script.
+
+Now type
+
+----
+make
+----
+
+to build the programs.
+
+If you want to build the manual in HTML, type
+
+----
+make docs
+----
+
+Once the programs have been successfully compiled, they need to be installed in
+their target locations. This step normally needs to be performed by the
+superuser, and requires the following command to be entered.
+
+----
+make install
+----
+
+This will install the binaries and man pages.
+
+To install the HTML version of the manual, enter the command
+
+----
+make install-docs
+----
+
+Now that the software is successfully installed, the next step is to set up a
+configuration file. The default location of the file is _/etc/chrony.conf_.
+Several examples of configuration with comments are included in the examples
+directory. Suppose you want to use public NTP servers from the pool.ntp.org
+project as your time reference. A minimal useful configuration file could be
+
+----
+pool pool.ntp.org iburst
+makestep 1.0 3
+rtcsync
+----
+
+Then, `chronyd` can be run. For security reasons, it's recommended to create an
+unprivileged user for `chronyd` and specify it with the `-u` command-line
+option or the `user` directive in the configuration file, or set the default
+user with the `--with-user` configure option before building.
+
+== Support for system call filtering
+
+`chronyd` can be built with support for the Linux secure computing (seccomp)
+facility. This requires development files for the
+https://github.com/seccomp/libseccomp[libseccomp] library and the
+`--enable-scfilter` option specified to `configure`. The `-F` option of
+`chronyd` will enable a system call filter, which should significantly reduce
+the kernel attack surface and possibly prevent kernel exploits from `chronyd`
+if it is compromised.
+
+== Extra options for package builders
+
+The `configure` and `make` procedures have some extra options that may be
+useful if you are building a distribution package for `chrony`.
+
+The `--mandir=DIR` option to `configure` specifies an installation directory
+for the man pages. This overrides the `man` subdirectory of the argument to the
+`--prefix` option.
+
+----
+./configure --prefix=/usr --mandir=/usr/share/man
+----
+
+to set both options together.
+
+The final option is the `DESTDIR` option to the `make` command. For example,
+you could use the commands
+
+----
+./configure --prefix=/usr --mandir=/usr/share/man
+make all docs
+make install DESTDIR=./tmp
+cd tmp
+tar cvf - . | gzip -9 > chrony.tar.gz
+----
+
+to build a package. When untarred within the root directory, this will install
+the files to the intended final locations.
diff --git a/examples/chrony-wait.service b/examples/chrony-wait.service
new file mode 100644
index 0000000..72b028f
--- /dev/null
+++ b/examples/chrony-wait.service
@@ -0,0 +1,47 @@
+[Unit]
+Description=Wait for chrony to synchronize system clock
+Documentation=man:chronyc(1)
+After=chronyd.service
+Requires=chronyd.service
+Before=time-sync.target
+Wants=time-sync.target
+
+[Service]
+Type=oneshot
+# Wait for chronyd to update the clock and the remaining
+# correction to be less than 0.1 seconds
+ExecStart=/usr/bin/chronyc -h 127.0.0.1,::1 waitsync 0 0.1 0.0 1
+# Wait for at most 3 minutes
+TimeoutStartSec=180
+RemainAfterExit=yes
+StandardOutput=null
+
+CapabilityBoundingSet=
+DevicePolicy=closed
+DynamicUser=yes
+IPAddressAllow=localhost
+IPAddressDeny=any
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+PrivateDevices=yes
+PrivateUsers=yes
+ProcSubset=pid
+ProtectClock=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+RestrictAddressFamilies=AF_INET AF_INET6
+RestrictNamespaces=yes
+RestrictRealtime=yes
+SystemCallArchitectures=native
+SystemCallFilter=@system-service
+SystemCallFilter=~@privileged @resources
+UMask=0777
+
+[Install]
+WantedBy=multi-user.target
diff --git a/examples/chrony.conf.example1 b/examples/chrony.conf.example1
new file mode 100644
index 0000000..5e93ea7
--- /dev/null
+++ b/examples/chrony.conf.example1
@@ -0,0 +1,12 @@
+# Use public NTP servers from the pool.ntp.org project.
+pool pool.ntp.org iburst
+
+# Record the rate at which the system clock gains/losses time.
+driftfile /var/lib/chrony/drift
+
+# Allow the system clock to be stepped in the first three updates
+# if its offset is larger than 1 second.
+makestep 1.0 3
+
+# Enable kernel synchronization of the real-time clock (RTC).
+rtcsync
diff --git a/examples/chrony.conf.example2 b/examples/chrony.conf.example2
new file mode 100644
index 0000000..bf2bbdd
--- /dev/null
+++ b/examples/chrony.conf.example2
@@ -0,0 +1,47 @@
+# Use public servers from the pool.ntp.org project.
+# Please consider joining the pool (https://www.pool.ntp.org/join.html).
+pool pool.ntp.org iburst
+
+# Record the rate at which the system clock gains/losses time.
+driftfile /var/lib/chrony/drift
+
+# Allow the system clock to be stepped in the first three updates
+# if its offset is larger than 1 second.
+makestep 1.0 3
+
+# Enable kernel synchronization of the real-time clock (RTC).
+rtcsync
+
+# Enable hardware timestamping on all interfaces that support it.
+#hwtimestamp *
+
+# Increase the minimum number of selectable sources required to adjust
+# the system clock.
+#minsources 2
+
+# Allow NTP client access from local network.
+#allow 192.168.0.0/16
+
+# Serve time even if not synchronized to a time source.
+#local stratum 10
+
+# Require authentication (nts or key option) for all NTP sources.
+#authselectmode require
+
+# Specify file containing keys for NTP authentication.
+#keyfile /etc/chrony.keys
+
+# Save NTS keys and cookies.
+ntsdumpdir /var/lib/chrony
+
+# Insert/delete leap seconds by slewing instead of stepping.
+#leapsecmode slew
+
+# Get TAI-UTC offset and leap seconds from the system tz database.
+#leapsectz right/UTC
+
+# Specify directory for log files.
+logdir /var/log/chrony
+
+# Select which information is logged.
+#log measurements statistics tracking
diff --git a/examples/chrony.conf.example3 b/examples/chrony.conf.example3
new file mode 100644
index 0000000..4e3e3a8
--- /dev/null
+++ b/examples/chrony.conf.example3
@@ -0,0 +1,334 @@
+#######################################################################
+#
+# This is an example chrony configuration file.  You should copy it to
+# /etc/chrony.conf after uncommenting and editing the options that you
+# want to enable.  The more obscure options are not included.  Refer
+# to the documentation for these.
+#
+#######################################################################
+### COMMENTS
+# Any of the following lines are comments (you have a choice of
+# comment start character):
+# a comment
+% a comment
+! a comment
+; a comment
+#
+# Below, the '!' form is used for lines that you might want to
+# uncomment and edit to make your own chrony.conf file.
+#
+#######################################################################
+#######################################################################
+### SPECIFY YOUR NTP SERVERS
+# Most computers using chrony will send measurement requests to one or
+# more 'NTP servers'.  You will probably find that your Internet Service
+# Provider or company have one or more NTP servers that you can specify.
+# Failing that, there are a lot of public NTP servers.  There is a list
+# you can access at http://support.ntp.org/bin/view/Servers/WebHome or
+# you can use servers from the pool.ntp.org project.
+
+! server foo.example.net iburst
+! server bar.example.net iburst
+! server baz.example.net iburst
+
+! pool pool.ntp.org iburst
+ 
+#######################################################################
+### AVOIDING POTENTIALLY BOGUS CHANGES TO YOUR CLOCK
+#
+# To avoid changes being made to your computer's gain/loss compensation
+# when the measurement history is too erratic, you might want to enable
+# one of the following lines.  The first seems good with servers on the
+# Internet, the second seems OK for a LAN environment.
+
+! maxupdateskew 100
+! maxupdateskew 5
+
+# If you want to increase the minimum number of selectable sources
+# required to update the system clock in order to make the
+# synchronisation more reliable, uncomment (and edit) the following
+# line.
+
+! minsources 2
+
+# If your computer has a good stable clock (e.g. it is not a virtual
+# machine), you might also want to reduce the maximum assumed drift
+# (frequency error) of the clock (the value is specified in ppm).
+
+! maxdrift 100
+
+# By default, chronyd allows synchronisation to an unauthenticated NTP
+# source (i.e. specified without the nts and key options) if it agrees with
+# a majority of authenticated NTP sources, or if no authenticated source is
+# specified.  If you don't want chronyd to ever synchronise to an
+# unauthenticated NTP source, uncomment the first from the following lines.
+# If you don't want to synchronise to an unauthenticated NTP source only
+# when an authenticated source is specified, uncomment the second line.
+# If you want chronyd to ignore authentication in the source selection,
+# uncomment the third line.
+
+! authselectmode require
+! authselectmode prefer
+! authselectmode ignore
+
+#######################################################################
+### FILENAMES ETC
+# Chrony likes to keep information about your computer's clock in files.
+# The 'driftfile' stores the computer's clock gain/loss rate in parts
+# per million.  When chronyd starts, the system clock can be tuned
+# immediately so that it doesn't gain or lose any more time.  You
+# generally want this, so it is uncommented.
+
+driftfile /var/lib/chrony/drift
+
+# If you want to enable NTP authentication with symmetric keys, you will need
+# to uncomment the following line and edit the file to set up the keys.
+
+! keyfile /etc/chrony.keys
+
+# If you specify an NTP server with the nts option to enable authentication
+# with the Network Time Security (NTS) mechanism, or enable server NTS with
+# the ntsservercert and ntsserverkey directives below, the following line will
+# allow the client/server to save the NTS keys and cookies in order to reduce
+# the number of key establishments (NTS-KE sessions).
+
+ntsdumpdir /var/lib/chrony
+
+# If chronyd is configured to act as an NTP server and you want to enable NTS
+# for its clients, you will need a TLS certificate and private key.  Uncomment
+# and edit the following lines to specify the locations of the certificate and
+# key.
+
+! ntsservercert /etc/.../foo.example.net.crt
+! ntsserverkey /etc/.../foo.example.net.key
+
+# chronyd can save the measurement history for the servers to files when
+# it exits.  This is useful in 2 situations:
+#
+# 1. If you stop chronyd and restart it with the '-r' option (e.g. after
+# an upgrade), the old measurements will still be relevant when chronyd
+# is restarted.  This will reduce the time needed to get accurate
+# gain/loss measurements.
+#
+# 2. On Linux, if you use the RTC support and start chronyd with
+# '-r -s' on bootup, measurements from the last boot will still be
+# useful (the real time clock is used to 'flywheel' chronyd between
+# boots).
+#
+# Uncomment the following line to use this.
+
+! dumpdir /var/lib/chrony
+
+# chronyd writes its process ID to a file.  If you try to start a second
+# copy of chronyd, it will detect that the process named in the file is
+# still running and bail out.  If you want to change the path to the PID
+# file, uncomment this line and edit it.  The default path is shown.
+
+! pidfile /var/run/chrony/chronyd.pid
+
+# If the system timezone database is kept up to date and includes the
+# right/UTC timezone, chronyd can use it to determine the current
+# TAI-UTC offset and when will the next leap second occur.
+
+! leapsectz right/UTC
+
+#######################################################################
+### INITIAL CLOCK CORRECTION
+# This option is useful to quickly correct the clock on start if it's
+# off by a large amount.  The value '1.0' means that if the error is less
+# than 1 second, it will be gradually removed by speeding up or slowing
+# down your computer's clock until it is correct.  If the error is above
+# 1 second, an immediate time jump will be applied to correct it.  The
+# value '3' means the step is allowed only in the first three updates of
+# the clock.  Some software can get upset if the system clock jumps
+# (especially backwards), so be careful!
+
+! makestep 1.0 3
+
+#######################################################################
+### LEAP SECONDS
+# A leap second is an occasional one-second correction of the UTC
+# time scale.  By default, chronyd tells the kernel to insert/delete
+# the leap second, which makes a backward/forward step to correct the
+# clock for it.  As with the makestep directive, this jump can upset
+# some applications.  If you prefer chronyd to make a gradual
+# correction, causing the clock to be off for a longer time, uncomment
+# the following line.
+
+! leapsecmode slew
+
+#######################################################################
+### LOGGING
+# If you want to log information about the time measurements chronyd has
+# gathered, you might want to enable the following lines.  You probably
+# only need this if you really enjoy looking at the logs, you want to
+# produce some graphs of your system's timekeeping performance, or you
+# need help in debugging a problem.
+
+! logdir /var/log/chrony
+! log measurements statistics tracking
+
+# If you have real time clock support enabled (see below), you might want
+# this line instead:
+
+! log measurements statistics tracking rtc
+
+#######################################################################
+### ACTING AS AN NTP SERVER
+# You might want the computer to be an NTP server for other computers.
+#
+# By default, chronyd does not allow any clients to access it.  You need
+# to explicitly enable access using 'allow' and 'deny' directives.
+#
+# e.g. to enable client access from the 192.168.*.* class B subnet,
+
+! allow 192.168/16
+
+# .. but disallow the 192.168.100.* subnet of that,
+
+! deny 192.168.100/24
+
+# You can have as many allow and deny directives as you need.  The order
+# is unimportant.
+
+# If you want to present your computer's time for others to synchronise
+# with, even if you don't seem to be synchronised to any NTP servers
+# yourself, enable the following line.  The value 10 may be varied
+# between 1 and 15.  You should avoid small values because you will look
+# like a real NTP server.  The value 10 means that you appear to be 10
+# NTP 'hops' away from an authoritative source (atomic clock, GPS
+# receiver, radio clock etc).
+
+! local stratum 10
+
+# Normally, chronyd will keep track of how many times each client
+# machine accesses it.  The information can be accessed by the 'clients'
+# command of chronyc.  You can disable this facility by uncommenting the
+# following line.  This will save a bit of memory if you have many
+# clients and it will also disable support for the interleaved mode.
+
+! noclientlog
+
+# The clientlog size is limited to 512KB by default.  If you have many
+# clients, you might want to increase the limit.
+
+! clientloglimit 4194304
+
+# By default, chronyd tries to respond to all valid NTP requests from
+# allowed addresses.  If you want to limit the response rate for NTP
+# clients that are sending requests too frequently, uncomment and edit
+# the following line.
+
+! ratelimit interval 3 burst 8
+
+#######################################################################
+### REPORTING BIG CLOCK CHANGES
+# Perhaps you want to know if chronyd suddenly detects any large error
+# in your computer's clock.  This might indicate a fault or a problem
+# with the server(s) you are using, for example.
+#
+# The next option causes a message to be written to syslog when chronyd
+# has to correct an error above 0.5 seconds (you can use any amount you
+# like).
+
+! logchange 0.5
+
+# The next option will send email to the named person when chronyd has
+# to correct an error above 0.5 seconds.  (If you need to send mail to
+# several people, you need to set up a mailing list or sendmail alias
+# for them and use the address of that.)
+
+! mailonchange wibble@foo.example.net 0.5
+
+#######################################################################
+### COMMAND ACCESS
+# The program chronyc is used to show the current operation of chronyd
+# and to change parts of its configuration whilst it is running.
+
+# By default chronyd binds to the loopback interface.  Uncomment the
+# following lines to allow receiving command packets from remote hosts.
+
+! bindcmdaddress 0.0.0.0
+! bindcmdaddress ::
+
+# Normally, chronyd will only allow connections from chronyc on the same
+# machine as itself.  This is for security.  If you have a subnet
+# 192.168.*.* and you want to be able to use chronyc from any machine on
+# it, you could uncomment the following line.  (Edit this to your own
+# situation.)
+
+! cmdallow 192.168/16
+
+# You can add as many 'cmdallow' and 'cmddeny' lines as you like.  The
+# syntax and meaning is the same as for 'allow' and 'deny', except that
+# 'cmdallow' and 'cmddeny' control access to the chronyd's command port.
+
+# Rate limiting can be enabled also for command packets.  (Note,
+# commands from localhost are never limited.)
+
+! cmdratelimit interval -4 burst 16
+
+#######################################################################
+### HARDWARE TIMESTAMPING
+# On Linux, if the network interface controller and its driver support
+# hardware timestamping, it can significantly improve the accuracy of
+# synchronisation. It can be enabled on specified interfaces only, or it
+# can be enabled on all interfaces that support it.
+
+! hwtimestamp eth0
+! hwtimestamp *
+
+#######################################################################
+### REAL TIME CLOCK
+# chronyd can characterise the system's real-time clock.  This is the
+# clock that keeps running when the power is turned off, so that the
+# machine knows the approximate time when it boots again.  The error at
+# a particular epoch and gain/loss rate can be written to a file and
+# used later by chronyd when it is started with the '-s' option.
+#
+# You need to have 'enhanced RTC support' compiled into your Linux
+# kernel.  (Note, these options apply only to Linux.)
+
+! rtcfile /var/lib/chrony/rtc
+
+# Your RTC can be set to keep Universal Coordinated Time (UTC) or local
+# time.  (Local time means UTC +/- the effect of your timezone.)  If you
+# use UTC, chronyd will function correctly even if the computer is off
+# at the epoch when you enter or leave summer time (aka daylight saving
+# time).  However, if you dual boot your system with Microsoft Windows,
+# that will work better if your RTC maintains local time.  You take your
+# pick!
+
+! rtconutc
+
+# By default chronyd assumes that the enhanced RTC device is accessed as
+# /dev/rtc.  If it's accessed somewhere else on your system (e.g. you're
+# using devfs), uncomment and edit the following line.
+
+! rtcdevice /dev/misc/rtc
+
+# Alternatively, if not using the -s option, this directive can be used
+# to enable a mode in which the RTC is periodically set to the system
+# time, with no tracking of its drift.
+
+! rtcsync
+
+#######################################################################
+### REAL TIME SCHEDULER
+# This directive tells chronyd to use the real-time FIFO scheduler with the
+# specified priority (which must be between 0 and 100).  This should result
+# in reduced latency.  You don't need it unless you really have a requirement
+# for extreme clock stability.  Works only on Linux.  Note that the "-P"
+# command-line switch will override this.
+
+! sched_priority 1
+
+#######################################################################
+### LOCKING CHRONYD INTO RAM
+# This directive tells chronyd to use the mlockall() syscall to lock itself
+# into RAM so that it will never be paged out.  This should result in reduced
+# latency.  You don't need it unless you really have a requirement
+# for extreme clock stability.  Works only on Linux.  Note that the "-m"
+# command-line switch will also enable this feature.
+
+! lock_all
diff --git a/examples/chrony.keys.example b/examples/chrony.keys.example
new file mode 100644
index 0000000..65b6be2
--- /dev/null
+++ b/examples/chrony.keys.example
@@ -0,0 +1,13 @@
+# This is an example chrony keys file.  It enables authentication of NTP
+# packets with symmetric keys when its location is specified by the keyfile
+# directive in chrony.conf(5).  It should be readable only by root and the
+# user under which chronyd is running.
+#
+# Don't use the example keys!  It's recommended to generate random keys using
+# the chronyc keygen command.
+
+# Examples of valid keys:
+
+#1 MD5 AVeryLongAndRandomPassword
+#2 MD5 HEX:12114855C7931009B4049EF3EFC48A139C3F989F
+#3 SHA1 HEX:B2159C05D6A219673A3B7E896B6DE07F6A440995
diff --git a/examples/chrony.logrotate b/examples/chrony.logrotate
new file mode 100644
index 0000000..2823a1a
--- /dev/null
+++ b/examples/chrony.logrotate
@@ -0,0 +1,8 @@
+/var/log/chrony/*.log {
+    missingok
+    nocreate
+    sharedscripts
+    postrotate
+        /usr/bin/chronyc cyclelogs > /dev/null 2>&1 || true
+    endscript
+}
diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
new file mode 100644
index 0000000..547ce83
--- /dev/null
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -0,0 +1,49 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher script for chronyd to update
+# its NTP sources with servers from DHCP options passed by NetworkManager
+# in the DHCP4_NTP_SERVERS and DHCP6_DHCP6_NTP_SERVERS environment variables.
+
+export LC_ALL=C
+
+interface=$1
+action=$2
+
+chronyc=/usr/bin/chronyc
+server_options=iburst
+server_dir=/var/run/chrony-dhcp
+
+dhcp_server_file=$server_dir/$interface.sources
+dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
+
+add_servers_from_dhcp() {
+    rm -f "$dhcp_server_file"
+    for server in $dhcp_ntp_servers; do
+        # Check for invalid characters (from the DHCPv6 NTP FQDN suboption)
+        len1=$(printf '%s' "$server" | wc -c)
+        len2=$(printf '%s' "$server" | tr -d -c 'A-Za-z0-9:.-' | wc -c)
+        if [ "$len1" -ne "$len2" ] || [ "$len2" -lt 1 ] || [ "$len2" -gt 255 ]; then
+          continue
+        fi
+
+        printf 'server %s %s\n' "$server" "$server_options" >> "$dhcp_server_file"
+    done
+    $chronyc reload sources > /dev/null 2>&1 || :
+}
+
+clear_servers_from_dhcp() {
+    if [ -f "$dhcp_server_file" ]; then
+        rm -f "$dhcp_server_file"
+        $chronyc reload sources > /dev/null 2>&1 || :
+    fi
+}
+
+mkdir -p $server_dir
+
+case "$action" in
+    up|dhcp4-change|dhcp6-change)
+        add_servers_from_dhcp;;
+    down)
+        clear_servers_from_dhcp;;
+esac
+
+exit 0
diff --git a/examples/chrony.nm-dispatcher.onoffline b/examples/chrony.nm-dispatcher.onoffline
new file mode 100644
index 0000000..01e6fdb
--- /dev/null
+++ b/examples/chrony.nm-dispatcher.onoffline
@@ -0,0 +1,27 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher / networkd-dispatcher script for
+# chronyd to set its NTP sources online or offline when a network interface
+# is configured or removed
+
+export LC_ALL=C
+
+chronyc=/usr/bin/chronyc
+
+# For NetworkManager consider only selected events
+if [ $# -ge 2 ]; then
+    case "$2" in
+        up|down|connectivity-change)
+            ;;
+        dhcp6-change)
+            # No other action is reported for routable IPv6
+            ;;
+        *)
+            exit 0;;
+    esac
+fi
+
+# Note: for networkd-dispatcher routable.d ~= on and off.d ~= off
+
+$chronyc onoffline > /dev/null 2>&1
+
+exit 0
diff --git a/examples/chronyd.service b/examples/chronyd.service
new file mode 100644
index 0000000..4fb930e
--- /dev/null
+++ b/examples/chronyd.service
@@ -0,0 +1,49 @@
+[Unit]
+Description=NTP client/server
+Documentation=man:chronyd(8) man:chrony.conf(5)
+After=ntpdate.service sntp.service ntpd.service
+Conflicts=ntpd.service systemd-timesyncd.service
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/sysconfig/chronyd
+ExecStart=/usr/sbin/chronyd $OPTIONS
+
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD CAP_SYS_ADMIN
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
+DeviceAllow=char-pps rw
+DeviceAllow=char-ptp rw
+DeviceAllow=char-rtc rw
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProcSubset=pid
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+ReadWritePaths=/run /var/lib/chrony -/var/log
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap
+
+# Adjust restrictions for /usr/sbin/sendmail (mailonchange directive)
+NoNewPrivileges=no
+ReadWritePaths=-/var/spool
+RestrictAddressFamilies=AF_NETLINK
+
+[Install]
+WantedBy=multi-user.target
diff --git a/getdate.c b/getdate.c
new file mode 100644
index 0000000..5c38119
--- /dev/null
+++ b/getdate.c
@@ -0,0 +1,2606 @@
+/* A Bison parser, made by GNU Bison 3.8.2.  */
+
+/* Bison implementation for Yacc-like parsers in C
+
+   Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2021 Free Software Foundation,
+   Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* As a special exception, you may create a larger work that contains
+   part or all of the Bison parser skeleton and distribute that work
+   under terms of your choice, so long as that work isn't itself a
+   parser generator using the skeleton or a modified version thereof
+   as a parser skeleton.  Alternatively, if you modify or redistribute
+   the parser skeleton itself, you may (at your option) remove this
+   special exception, which will cause the skeleton and the resulting
+   Bison output files to be licensed under the GNU General Public
+   License without this special exception.
+
+   This special exception was added by the Free Software Foundation in
+   version 2.2 of Bison.  */
+
+/* C LALR(1) parser skeleton written by Richard Stallman, by
+   simplifying the original so-called "semantic" parser.  */
+
+/* DO NOT RELY ON FEATURES THAT ARE NOT DOCUMENTED in the manual,
+   especially those whose name start with YY_ or yy_.  They are
+   private implementation details that can be changed or removed.  */
+
+/* All symbols defined below should begin with yy or YY, to avoid
+   infringing on user name space.  This should be done even for local
+   variables, as they might otherwise be expanded by user macros.
+   There are some unavoidable exceptions within include files to
+   define necessary library symbols; they are noted "INFRINGES ON
+   USER NAME SPACE" below.  */
+
+/* Identify Bison output, and Bison version.  */
+#define YYBISON 30802
+
+/* Bison version string.  */
+#define YYBISON_VERSION "3.8.2"
+
+/* Skeleton name.  */
+#define YYSKELETON_NAME "yacc.c"
+
+/* Pure parsers.  */
+#define YYPURE 0
+
+/* Push parsers.  */
+#define YYPUSH 0
+
+/* Pull parsers.  */
+#define YYPULL 1
+
+
+
+
+/* First part of user prologue.  */
+#line 1 "getdate.y"
+
+/*
+**  Originally written by Steven M. Bellovin <smb@research.att.com> while
+**  at the University of North Carolina at Chapel Hill.  Later tweaked by
+**  a couple of people on Usenet.  Completely overhauled by Rich $alz
+**  <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
+**
+**  This code is in the public domain and has no copyright.
+*/
+
+#include "config.h"
+
+/* Since the code of getdate.y is not included in the Emacs executable
+   itself, there is no need to #define static in this file.  Even if
+   the code were included in the Emacs executable, it probably
+   wouldn't do any harm to #undef it here; this will only cause
+   problems if we try to write to a static variable, which I don't
+   think this code needs to do.  */
+#ifdef emacs
+# undef static
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+
+#if HAVE_STDLIB_H
+# include <stdlib.h> /* for `free'; used by Bison 1.27 */
+#endif
+
+#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+#endif
+
+#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
+#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
+#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c))
+#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+
+/* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
+   only '0' through '9' are digits.  Prefer ISDIGIT to ISDIGIT_LOCALE unless
+   it's important to use the locale's definition of `digit' even when the
+   host does not conform to Posix.  */
+#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
+
+#if defined (STDC_HEADERS) || defined (USG)
+# include <string.h>
+#endif
+
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
+# define __attribute__(x)
+#endif
+
+#ifndef ATTRIBUTE_UNUSED
+# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#endif
+
+/* Some old versions of bison generate parsers that use bcopy.
+   That loses on systems that don't provide the function, so we have
+   to redefine it here.  */
+#if !defined (HAVE_BCOPY) && defined (HAVE_MEMCPY) && !defined (bcopy)
+# define bcopy(from, to, len) memcpy ((to), (from), (len))
+#endif
+
+/* Remap normal yacc parser interface names (yyparse, yylex, yyerror, etc),
+   as well as gratuitiously global symbol names, so we can have multiple
+   yacc generated parsers in the same program.  Note that these are only
+   the variables produced by yacc.  If other parser generators (bison,
+   byacc, etc) produce additional global names that conflict at link time,
+   then those parser generators need to be fixed instead of adding those
+   names to this list. */
+
+#define yymaxdepth gd_maxdepth
+#define yyparse gd_parse
+#define yylex   gd_lex
+#define yyerror gd_error
+#define yylval  gd_lval
+#define yychar  gd_char
+#define yydebug gd_debug
+#define yypact  gd_pact
+#define yyr1    gd_r1
+#define yyr2    gd_r2
+#define yydef   gd_def
+#define yychk   gd_chk
+#define yypgo   gd_pgo
+#define yyact   gd_act
+#define yyexca  gd_exca
+#define yyerrflag gd_errflag
+#define yynerrs gd_nerrs
+#define yyps    gd_ps
+#define yypv    gd_pv
+#define yys     gd_s
+#define yy_yys  gd_yys
+#define yystate gd_state
+#define yytmp   gd_tmp
+#define yyv     gd_v
+#define yy_yyv  gd_yyv
+#define yyval   gd_val
+#define yylloc  gd_lloc
+#define yyreds  gd_reds          /* With YYDEBUG defined */
+#define yytoks  gd_toks          /* With YYDEBUG defined */
+#define yylhs   gd_yylhs
+#define yylen   gd_yylen
+#define yydefred gd_yydefred
+#define yydgoto gd_yydgoto
+#define yysindex gd_yysindex
+#define yyrindex gd_yyrindex
+#define yygindex gd_yygindex
+#define yytable  gd_yytable
+#define yycheck  gd_yycheck
+
+static int yylex (void);
+static int yyerror (char *s);
+
+#define EPOCH		1970
+#define HOUR(x)		((x) * 60)
+
+#define MAX_BUFF_LEN    128   /* size of buffer to read the date into */
+
+/*
+**  An entry in the lexical lookup table.
+*/
+typedef struct _TABLE {
+    const char	*name;
+    int		type;
+    int		value;
+} TABLE;
+
+
+/*
+**  Meridian:  am, pm, or 24-hour style.
+*/
+typedef enum _MERIDIAN {
+    MERam, MERpm, MER24
+} MERIDIAN;
+
+
+/*
+**  Global variables.  We could get rid of most of these by using a good
+**  union as the yacc stack.  (This routine was originally written before
+**  yacc had the %union construct.)  Maybe someday; right now we only use
+**  the %union very rarely.
+*/
+static const char	*yyInput;
+static int	yyDayOrdinal;
+static int	yyDayNumber;
+static int	yyHaveDate;
+static int	yyHaveDay;
+static int	yyHaveRel;
+static int	yyHaveTime;
+static int	yyHaveZone;
+static int	yyTimezone;
+static int	yyDay;
+static int	yyHour;
+static int	yyMinutes;
+static int	yyMonth;
+static int	yySeconds;
+static int	yyYear;
+static MERIDIAN	yyMeridian;
+static int	yyRelDay;
+static int	yyRelHour;
+static int	yyRelMinutes;
+static int	yyRelMonth;
+static int	yyRelSeconds;
+static int	yyRelYear;
+
+
+#line 244 "getdate.c"
+
+# ifndef YY_CAST
+#  ifdef __cplusplus
+#   define YY_CAST(Type, Val) static_cast<Type> (Val)
+#   define YY_REINTERPRET_CAST(Type, Val) reinterpret_cast<Type> (Val)
+#  else
+#   define YY_CAST(Type, Val) ((Type) (Val))
+#   define YY_REINTERPRET_CAST(Type, Val) ((Type) (Val))
+#  endif
+# endif
+# ifndef YY_NULLPTR
+#  if defined __cplusplus
+#   if 201103L <= __cplusplus
+#    define YY_NULLPTR nullptr
+#   else
+#    define YY_NULLPTR 0
+#   endif
+#  else
+#   define YY_NULLPTR ((void*)0)
+#  endif
+# endif
+
+
+/* Debug traces.  */
+#ifndef YYDEBUG
+# define YYDEBUG 0
+#endif
+#if YYDEBUG
+extern int yydebug;
+#endif
+
+/* Token kinds.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+  enum yytokentype
+  {
+    YYEMPTY = -2,
+    YYEOF = 0,                     /* "end of file"  */
+    YYerror = 256,                 /* error  */
+    YYUNDEF = 257,                 /* "invalid token"  */
+    tAGO = 258,                    /* tAGO  */
+    tDAY = 259,                    /* tDAY  */
+    tDAY_UNIT = 260,               /* tDAY_UNIT  */
+    tDAYZONE = 261,                /* tDAYZONE  */
+    tDST = 262,                    /* tDST  */
+    tHOUR_UNIT = 263,              /* tHOUR_UNIT  */
+    tID = 264,                     /* tID  */
+    tMERIDIAN = 265,               /* tMERIDIAN  */
+    tMINUTE_UNIT = 266,            /* tMINUTE_UNIT  */
+    tMONTH = 267,                  /* tMONTH  */
+    tMONTH_UNIT = 268,             /* tMONTH_UNIT  */
+    tSEC_UNIT = 269,               /* tSEC_UNIT  */
+    tSNUMBER = 270,                /* tSNUMBER  */
+    tUNUMBER = 271,                /* tUNUMBER  */
+    tYEAR_UNIT = 272,              /* tYEAR_UNIT  */
+    tZONE = 273                    /* tZONE  */
+  };
+  typedef enum yytokentype yytoken_kind_t;
+#endif
+
+/* Value type.  */
+#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
+union YYSTYPE
+{
+#line 177 "getdate.y"
+
+    int			Number;
+    enum _MERIDIAN	Meridian;
+
+#line 314 "getdate.c"
+
+};
+typedef union YYSTYPE YYSTYPE;
+# define YYSTYPE_IS_TRIVIAL 1
+# define YYSTYPE_IS_DECLARED 1
+#endif
+
+
+extern YYSTYPE yylval;
+
+
+int yyparse (void);
+
+
+
+/* Symbol kind.  */
+enum yysymbol_kind_t
+{
+  YYSYMBOL_YYEMPTY = -2,
+  YYSYMBOL_YYEOF = 0,                      /* "end of file"  */
+  YYSYMBOL_YYerror = 1,                    /* error  */
+  YYSYMBOL_YYUNDEF = 2,                    /* "invalid token"  */
+  YYSYMBOL_tAGO = 3,                       /* tAGO  */
+  YYSYMBOL_tDAY = 4,                       /* tDAY  */
+  YYSYMBOL_tDAY_UNIT = 5,                  /* tDAY_UNIT  */
+  YYSYMBOL_tDAYZONE = 6,                   /* tDAYZONE  */
+  YYSYMBOL_tDST = 7,                       /* tDST  */
+  YYSYMBOL_tHOUR_UNIT = 8,                 /* tHOUR_UNIT  */
+  YYSYMBOL_tID = 9,                        /* tID  */
+  YYSYMBOL_tMERIDIAN = 10,                 /* tMERIDIAN  */
+  YYSYMBOL_tMINUTE_UNIT = 11,              /* tMINUTE_UNIT  */
+  YYSYMBOL_tMONTH = 12,                    /* tMONTH  */
+  YYSYMBOL_tMONTH_UNIT = 13,               /* tMONTH_UNIT  */
+  YYSYMBOL_tSEC_UNIT = 14,                 /* tSEC_UNIT  */
+  YYSYMBOL_tSNUMBER = 15,                  /* tSNUMBER  */
+  YYSYMBOL_tUNUMBER = 16,                  /* tUNUMBER  */
+  YYSYMBOL_tYEAR_UNIT = 17,                /* tYEAR_UNIT  */
+  YYSYMBOL_tZONE = 18,                     /* tZONE  */
+  YYSYMBOL_19_ = 19,                       /* ':'  */
+  YYSYMBOL_20_ = 20,                       /* ','  */
+  YYSYMBOL_21_ = 21,                       /* '/'  */
+  YYSYMBOL_YYACCEPT = 22,                  /* $accept  */
+  YYSYMBOL_spec = 23,                      /* spec  */
+  YYSYMBOL_item = 24,                      /* item  */
+  YYSYMBOL_time = 25,                      /* time  */
+  YYSYMBOL_zone = 26,                      /* zone  */
+  YYSYMBOL_day = 27,                       /* day  */
+  YYSYMBOL_date = 28,                      /* date  */
+  YYSYMBOL_rel = 29,                       /* rel  */
+  YYSYMBOL_relunit = 30,                   /* relunit  */
+  YYSYMBOL_number = 31,                    /* number  */
+  YYSYMBOL_o_merid = 32                    /* o_merid  */
+};
+typedef enum yysymbol_kind_t yysymbol_kind_t;
+
+
+
+
+#ifdef short
+# undef short
+#endif
+
+/* On compilers that do not define __PTRDIFF_MAX__ etc., make sure
+   <limits.h> and (if available) <stdint.h> are included
+   so that the code can choose integer types of a good width.  */
+
+#ifndef __PTRDIFF_MAX__
+# include <limits.h> /* INFRINGES ON USER NAME SPACE */
+# if defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
+#  include <stdint.h> /* INFRINGES ON USER NAME SPACE */
+#  define YY_STDINT_H
+# endif
+#endif
+
+/* Narrow types that promote to a signed type and that can represent a
+   signed or unsigned integer of at least N bits.  In tables they can
+   save space and decrease cache pressure.  Promoting to a signed type
+   helps avoid bugs in integer arithmetic.  */
+
+#ifdef __INT_LEAST8_MAX__
+typedef __INT_LEAST8_TYPE__ yytype_int8;
+#elif defined YY_STDINT_H
+typedef int_least8_t yytype_int8;
+#else
+typedef signed char yytype_int8;
+#endif
+
+#ifdef __INT_LEAST16_MAX__
+typedef __INT_LEAST16_TYPE__ yytype_int16;
+#elif defined YY_STDINT_H
+typedef int_least16_t yytype_int16;
+#else
+typedef short yytype_int16;
+#endif
+
+/* Work around bug in HP-UX 11.23, which defines these macros
+   incorrectly for preprocessor constants.  This workaround can likely
+   be removed in 2023, as HPE has promised support for HP-UX 11.23
+   (aka HP-UX 11i v2) only through the end of 2022; see Table 2 of
+   <https://h20195.www2.hpe.com/V2/getpdf.aspx/4AA4-7673ENW.pdf>.  */
+#ifdef __hpux
+# undef UINT_LEAST8_MAX
+# undef UINT_LEAST16_MAX
+# define UINT_LEAST8_MAX 255
+# define UINT_LEAST16_MAX 65535
+#endif
+
+#if defined __UINT_LEAST8_MAX__ && __UINT_LEAST8_MAX__ <= __INT_MAX__
+typedef __UINT_LEAST8_TYPE__ yytype_uint8;
+#elif (!defined __UINT_LEAST8_MAX__ && defined YY_STDINT_H \
+       && UINT_LEAST8_MAX <= INT_MAX)
+typedef uint_least8_t yytype_uint8;
+#elif !defined __UINT_LEAST8_MAX__ && UCHAR_MAX <= INT_MAX
+typedef unsigned char yytype_uint8;
+#else
+typedef short yytype_uint8;
+#endif
+
+#if defined __UINT_LEAST16_MAX__ && __UINT_LEAST16_MAX__ <= __INT_MAX__
+typedef __UINT_LEAST16_TYPE__ yytype_uint16;
+#elif (!defined __UINT_LEAST16_MAX__ && defined YY_STDINT_H \
+       && UINT_LEAST16_MAX <= INT_MAX)
+typedef uint_least16_t yytype_uint16;
+#elif !defined __UINT_LEAST16_MAX__ && USHRT_MAX <= INT_MAX
+typedef unsigned short yytype_uint16;
+#else
+typedef int yytype_uint16;
+#endif
+
+#ifndef YYPTRDIFF_T
+# if defined __PTRDIFF_TYPE__ && defined __PTRDIFF_MAX__
+#  define YYPTRDIFF_T __PTRDIFF_TYPE__
+#  define YYPTRDIFF_MAXIMUM __PTRDIFF_MAX__
+# elif defined PTRDIFF_MAX
+#  ifndef ptrdiff_t
+#   include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  endif
+#  define YYPTRDIFF_T ptrdiff_t
+#  define YYPTRDIFF_MAXIMUM PTRDIFF_MAX
+# else
+#  define YYPTRDIFF_T long
+#  define YYPTRDIFF_MAXIMUM LONG_MAX
+# endif
+#endif
+
+#ifndef YYSIZE_T
+# ifdef __SIZE_TYPE__
+#  define YYSIZE_T __SIZE_TYPE__
+# elif defined size_t
+#  define YYSIZE_T size_t
+# elif defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
+#  include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  define YYSIZE_T size_t
+# else
+#  define YYSIZE_T unsigned
+# endif
+#endif
+
+#define YYSIZE_MAXIMUM                                  \
+  YY_CAST (YYPTRDIFF_T,                                 \
+           (YYPTRDIFF_MAXIMUM < YY_CAST (YYSIZE_T, -1)  \
+            ? YYPTRDIFF_MAXIMUM                         \
+            : YY_CAST (YYSIZE_T, -1)))
+
+#define YYSIZEOF(X) YY_CAST (YYPTRDIFF_T, sizeof (X))
+
+
+/* Stored state numbers (used for stacks). */
+typedef yytype_int8 yy_state_t;
+
+/* State numbers in computations.  */
+typedef int yy_state_fast_t;
+
+#ifndef YY_
+# if defined YYENABLE_NLS && YYENABLE_NLS
+#  if ENABLE_NLS
+#   include <libintl.h> /* INFRINGES ON USER NAME SPACE */
+#   define YY_(Msgid) dgettext ("bison-runtime", Msgid)
+#  endif
+# endif
+# ifndef YY_
+#  define YY_(Msgid) Msgid
+# endif
+#endif
+
+
+#ifndef YY_ATTRIBUTE_PURE
+# if defined __GNUC__ && 2 < __GNUC__ + (96 <= __GNUC_MINOR__)
+#  define YY_ATTRIBUTE_PURE __attribute__ ((__pure__))
+# else
+#  define YY_ATTRIBUTE_PURE
+# endif
+#endif
+
+#ifndef YY_ATTRIBUTE_UNUSED
+# if defined __GNUC__ && 2 < __GNUC__ + (7 <= __GNUC_MINOR__)
+#  define YY_ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+# else
+#  define YY_ATTRIBUTE_UNUSED
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E.  */
+#if ! defined lint || defined __GNUC__
+# define YY_USE(E) ((void) (E))
+#else
+# define YY_USE(E) /* empty */
+#endif
+
+/* Suppress an incorrect diagnostic about yylval being uninitialized.  */
+#if defined __GNUC__ && ! defined __ICC && 406 <= __GNUC__ * 100 + __GNUC_MINOR__
+# if __GNUC__ * 100 + __GNUC_MINOR__ < 407
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")
+# else
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")              \
+    _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# endif
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END      \
+    _Pragma ("GCC diagnostic pop")
+#else
+# define YY_INITIAL_VALUE(Value) Value
+#endif
+#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END
+#endif
+#ifndef YY_INITIAL_VALUE
+# define YY_INITIAL_VALUE(Value) /* Nothing. */
+#endif
+
+#if defined __cplusplus && defined __GNUC__ && ! defined __ICC && 6 <= __GNUC__
+# define YY_IGNORE_USELESS_CAST_BEGIN                          \
+    _Pragma ("GCC diagnostic push")                            \
+    _Pragma ("GCC diagnostic ignored \"-Wuseless-cast\"")
+# define YY_IGNORE_USELESS_CAST_END            \
+    _Pragma ("GCC diagnostic pop")
+#endif
+#ifndef YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_END
+#endif
+
+
+#define YY_ASSERT(E) ((void) (0 && (E)))
+
+#if !defined yyoverflow
+
+/* The parser invokes alloca or malloc; define the necessary symbols.  */
+
+# ifdef YYSTACK_USE_ALLOCA
+#  if YYSTACK_USE_ALLOCA
+#   ifdef __GNUC__
+#    define YYSTACK_ALLOC __builtin_alloca
+#   elif defined __BUILTIN_VA_ARG_INCR
+#    include <alloca.h> /* INFRINGES ON USER NAME SPACE */
+#   elif defined _AIX
+#    define YYSTACK_ALLOC __alloca
+#   elif defined _MSC_VER
+#    include <malloc.h> /* INFRINGES ON USER NAME SPACE */
+#    define alloca _alloca
+#   else
+#    define YYSTACK_ALLOC alloca
+#    if ! defined _ALLOCA_H && ! defined EXIT_SUCCESS
+#     include <stdlib.h> /* INFRINGES ON USER NAME SPACE */
+      /* Use EXIT_SUCCESS as a witness for stdlib.h.  */
+#     ifndef EXIT_SUCCESS
+#      define EXIT_SUCCESS 0
+#     endif
+#    endif
+#   endif
+#  endif
+# endif
+
+# ifdef YYSTACK_ALLOC
+   /* Pacify GCC's 'empty if-body' warning.  */
+#  define YYSTACK_FREE(Ptr) do { /* empty */; } while (0)
+#  ifndef YYSTACK_ALLOC_MAXIMUM
+    /* The OS might guarantee only one guard page at the bottom of the stack,
+       and a page size can be as small as 4096 bytes.  So we cannot safely
+       invoke alloca (N) if N exceeds 4096.  Use a slightly smaller number
+       to allow for a few compiler-allocated temporary stack slots.  */
+#   define YYSTACK_ALLOC_MAXIMUM 4032 /* reasonable circa 2006 */
+#  endif
+# else
+#  define YYSTACK_ALLOC YYMALLOC
+#  define YYSTACK_FREE YYFREE
+#  ifndef YYSTACK_ALLOC_MAXIMUM
+#   define YYSTACK_ALLOC_MAXIMUM YYSIZE_MAXIMUM
+#  endif
+#  if (defined __cplusplus && ! defined EXIT_SUCCESS \
+       && ! ((defined YYMALLOC || defined malloc) \
+             && (defined YYFREE || defined free)))
+#   include <stdlib.h> /* INFRINGES ON USER NAME SPACE */
+#   ifndef EXIT_SUCCESS
+#    define EXIT_SUCCESS 0
+#   endif
+#  endif
+#  ifndef YYMALLOC
+#   define YYMALLOC malloc
+#   if ! defined malloc && ! defined EXIT_SUCCESS
+void *malloc (YYSIZE_T); /* INFRINGES ON USER NAME SPACE */
+#   endif
+#  endif
+#  ifndef YYFREE
+#   define YYFREE free
+#   if ! defined free && ! defined EXIT_SUCCESS
+void free (void *); /* INFRINGES ON USER NAME SPACE */
+#   endif
+#  endif
+# endif
+#endif /* !defined yyoverflow */
+
+#if (! defined yyoverflow \
+     && (! defined __cplusplus \
+         || (defined YYSTYPE_IS_TRIVIAL && YYSTYPE_IS_TRIVIAL)))
+
+/* A type that is properly aligned for any stack member.  */
+union yyalloc
+{
+  yy_state_t yyss_alloc;
+  YYSTYPE yyvs_alloc;
+};
+
+/* The size of the maximum gap between one aligned stack and the next.  */
+# define YYSTACK_GAP_MAXIMUM (YYSIZEOF (union yyalloc) - 1)
+
+/* The size of an array large to enough to hold all stacks, each with
+   N elements.  */
+# define YYSTACK_BYTES(N) \
+     ((N) * (YYSIZEOF (yy_state_t) + YYSIZEOF (YYSTYPE)) \
+      + YYSTACK_GAP_MAXIMUM)
+
+# define YYCOPY_NEEDED 1
+
+/* Relocate STACK from its old location to the new one.  The
+   local variables YYSIZE and YYSTACKSIZE give the old and new number of
+   elements in the stack, and YYPTR gives the new location of the
+   stack.  Advance YYPTR to a properly aligned location for the next
+   stack.  */
+# define YYSTACK_RELOCATE(Stack_alloc, Stack)                           \
+    do                                                                  \
+      {                                                                 \
+        YYPTRDIFF_T yynewbytes;                                         \
+        YYCOPY (&yyptr->Stack_alloc, Stack, yysize);                    \
+        Stack = &yyptr->Stack_alloc;                                    \
+        yynewbytes = yystacksize * YYSIZEOF (*Stack) + YYSTACK_GAP_MAXIMUM; \
+        yyptr += yynewbytes / YYSIZEOF (*yyptr);                        \
+      }                                                                 \
+    while (0)
+
+#endif
+
+#if defined YYCOPY_NEEDED && YYCOPY_NEEDED
+/* Copy COUNT objects from SRC to DST.  The source and destination do
+   not overlap.  */
+# ifndef YYCOPY
+#  if defined __GNUC__ && 1 < __GNUC__
+#   define YYCOPY(Dst, Src, Count) \
+      __builtin_memcpy (Dst, Src, YY_CAST (YYSIZE_T, (Count)) * sizeof (*(Src)))
+#  else
+#   define YYCOPY(Dst, Src, Count)              \
+      do                                        \
+        {                                       \
+          YYPTRDIFF_T yyi;                      \
+          for (yyi = 0; yyi < (Count); yyi++)   \
+            (Dst)[yyi] = (Src)[yyi];            \
+        }                                       \
+      while (0)
+#  endif
+# endif
+#endif /* !YYCOPY_NEEDED */
+
+/* YYFINAL -- State number of the termination state.  */
+#define YYFINAL  2
+/* YYLAST -- Last index in YYTABLE.  */
+#define YYLAST   50
+
+/* YYNTOKENS -- Number of terminals.  */
+#define YYNTOKENS  22
+/* YYNNTS -- Number of nonterminals.  */
+#define YYNNTS  11
+/* YYNRULES -- Number of rules.  */
+#define YYNRULES  51
+/* YYNSTATES -- Number of states.  */
+#define YYNSTATES  61
+
+/* YYMAXUTOK -- Last valid token kind.  */
+#define YYMAXUTOK   273
+
+
+/* YYTRANSLATE(TOKEN-NUM) -- Symbol number corresponding to TOKEN-NUM
+   as returned by yylex, with out-of-bounds checking.  */
+#define YYTRANSLATE(YYX)                                \
+  (0 <= (YYX) && (YYX) <= YYMAXUTOK                     \
+   ? YY_CAST (yysymbol_kind_t, yytranslate[YYX])        \
+   : YYSYMBOL_YYUNDEF)
+
+/* YYTRANSLATE[TOKEN-NUM] -- Symbol number corresponding to TOKEN-NUM
+   as returned by yylex.  */
+static const yytype_int8 yytranslate[] =
+{
+       0,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,    20,     2,     2,    21,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,    19,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     1,     2,     3,     4,
+       5,     6,     7,     8,     9,    10,    11,    12,    13,    14,
+      15,    16,    17,    18
+};
+
+#if YYDEBUG
+/* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
+static const yytype_int16 yyrline[] =
+{
+       0,   193,   193,   194,   197,   200,   203,   206,   209,   212,
+     215,   221,   227,   236,   242,   254,   257,   261,   266,   270,
+     274,   280,   284,   302,   308,   314,   318,   323,   327,   334,
+     342,   345,   348,   351,   354,   357,   360,   363,   366,   369,
+     372,   375,   378,   381,   384,   387,   390,   393,   396,   401,
+     435,   438
+};
+#endif
+
+/** Accessing symbol of state STATE.  */
+#define YY_ACCESSING_SYMBOL(State) YY_CAST (yysymbol_kind_t, yystos[State])
+
+#if YYDEBUG || 0
+/* The user-facing name of the symbol whose (internal) number is
+   YYSYMBOL.  No bounds checking.  */
+static const char *yysymbol_name (yysymbol_kind_t yysymbol) YY_ATTRIBUTE_UNUSED;
+
+/* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+   First, the terminals, then, starting at YYNTOKENS, nonterminals.  */
+static const char *const yytname[] =
+{
+  "\"end of file\"", "error", "\"invalid token\"", "tAGO", "tDAY",
+  "tDAY_UNIT", "tDAYZONE", "tDST", "tHOUR_UNIT", "tID", "tMERIDIAN",
+  "tMINUTE_UNIT", "tMONTH", "tMONTH_UNIT", "tSEC_UNIT", "tSNUMBER",
+  "tUNUMBER", "tYEAR_UNIT", "tZONE", "':'", "','", "'/'", "$accept",
+  "spec", "item", "time", "zone", "day", "date", "rel", "relunit",
+  "number", "o_merid", YY_NULLPTR
+};
+
+static const char *
+yysymbol_name (yysymbol_kind_t yysymbol)
+{
+  return yytname[yysymbol];
+}
+#endif
+
+#define YYPACT_NINF (-20)
+
+#define yypact_value_is_default(Yyn) \
+  ((Yyn) == YYPACT_NINF)
+
+#define YYTABLE_NINF (-1)
+
+#define yytable_value_is_error(Yyn) \
+  0
+
+/* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
+   STATE-NUM.  */
+static const yytype_int8 yypact[] =
+{
+     -20,     0,   -20,   -19,   -20,   -20,   -20,   -20,   -13,   -20,
+     -20,    30,    15,   -20,    14,   -20,   -20,   -20,   -20,   -20,
+     -20,    19,   -20,   -20,     4,   -20,   -20,   -20,   -20,   -20,
+     -20,   -20,   -20,   -20,   -20,   -20,    -6,   -20,   -20,    16,
+     -20,    17,    23,   -20,   -20,    24,   -20,   -20,   -20,    27,
+      28,   -20,   -20,   -20,    29,   -20,    32,    -8,   -20,   -20,
+     -20
+};
+
+/* YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
+   Performed when YYTABLE does not specify something else to do.  Zero
+   means the default is an error.  */
+static const yytype_int8 yydefact[] =
+{
+       2,     0,     1,    18,    39,    16,    42,    45,     0,    36,
+      48,     0,    49,    33,    15,     3,     4,     5,     7,     6,
+       8,    30,     9,    19,    25,    38,    41,    44,    35,    47,
+      32,    20,    37,    40,    10,    43,    27,    34,    46,     0,
+      31,     0,     0,    17,    29,     0,    24,    28,    23,    50,
+      21,    26,    51,    12,     0,    11,     0,    50,    22,    14,
+      13
+};
+
+/* YYPGOTO[NTERM-NUM].  */
+static const yytype_int8 yypgoto[] =
+{
+     -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,
+      -7
+};
+
+/* YYDEFGOTO[NTERM-NUM].  */
+static const yytype_int8 yydefgoto[] =
+{
+       0,     1,    15,    16,    17,    18,    19,    20,    21,    22,
+      55
+};
+
+/* YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
+   positive, shift that token.  If negative, reduce the rule whose
+   number is the opposite.  If YYTABLE_NINF, syntax error.  */
+static const yytype_int8 yytable[] =
+{
+       2,    23,    52,    24,     3,     4,     5,    59,     6,    46,
+      47,     7,     8,     9,    10,    11,    12,    13,    14,    31,
+      32,    43,    44,    33,    45,    34,    35,    36,    37,    38,
+      39,    48,    40,    49,    41,    25,    42,    52,    26,    50,
+      51,    27,    53,    28,    29,    57,    54,    30,    58,    56,
+      60
+};
+
+static const yytype_int8 yycheck[] =
+{
+       0,    20,    10,    16,     4,     5,     6,    15,     8,    15,
+      16,    11,    12,    13,    14,    15,    16,    17,    18,     4,
+       5,     7,     3,     8,    20,    10,    11,    12,    13,    14,
+      15,    15,    17,    16,    19,     5,    21,    10,     8,    16,
+      16,    11,    15,    13,    14,    16,    19,    17,    16,    21,
+      57
+};
+
+/* YYSTOS[STATE-NUM] -- The symbol kind of the accessing symbol of
+   state STATE-NUM.  */
+static const yytype_int8 yystos[] =
+{
+       0,    23,     0,     4,     5,     6,     8,    11,    12,    13,
+      14,    15,    16,    17,    18,    24,    25,    26,    27,    28,
+      29,    30,    31,    20,    16,     5,     8,    11,    13,    14,
+      17,     4,     5,     8,    10,    11,    12,    13,    14,    15,
+      17,    19,    21,     7,     3,    20,    15,    16,    15,    16,
+      16,    16,    10,    15,    19,    32,    21,    16,    16,    15,
+      32
+};
+
+/* YYR1[RULE-NUM] -- Symbol kind of the left-hand side of rule RULE-NUM.  */
+static const yytype_int8 yyr1[] =
+{
+       0,    22,    23,    23,    24,    24,    24,    24,    24,    24,
+      25,    25,    25,    25,    25,    26,    26,    26,    27,    27,
+      27,    28,    28,    28,    28,    28,    28,    28,    28,    29,
+      29,    30,    30,    30,    30,    30,    30,    30,    30,    30,
+      30,    30,    30,    30,    30,    30,    30,    30,    30,    31,
+      32,    32
+};
+
+/* YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM.  */
+static const yytype_int8 yyr2[] =
+{
+       0,     2,     0,     2,     1,     1,     1,     1,     1,     1,
+       2,     4,     4,     6,     6,     1,     1,     2,     1,     2,
+       2,     3,     5,     3,     3,     2,     4,     2,     3,     2,
+       1,     2,     2,     1,     2,     2,     1,     2,     2,     1,
+       2,     2,     1,     2,     2,     1,     2,     2,     1,     1,
+       0,     1
+};
+
+
+enum { YYENOMEM = -2 };
+
+#define yyerrok         (yyerrstatus = 0)
+#define yyclearin       (yychar = YYEMPTY)
+
+#define YYACCEPT        goto yyacceptlab
+#define YYABORT         goto yyabortlab
+#define YYERROR         goto yyerrorlab
+#define YYNOMEM         goto yyexhaustedlab
+
+
+#define YYRECOVERING()  (!!yyerrstatus)
+
+#define YYBACKUP(Token, Value)                                    \
+  do                                                              \
+    if (yychar == YYEMPTY)                                        \
+      {                                                           \
+        yychar = (Token);                                         \
+        yylval = (Value);                                         \
+        YYPOPSTACK (yylen);                                       \
+        yystate = *yyssp;                                         \
+        goto yybackup;                                            \
+      }                                                           \
+    else                                                          \
+      {                                                           \
+        yyerror (YY_("syntax error: cannot back up")); \
+        YYERROR;                                                  \
+      }                                                           \
+  while (0)
+
+/* Backward compatibility with an undocumented macro.
+   Use YYerror or YYUNDEF. */
+#define YYERRCODE YYUNDEF
+
+
+/* Enable debugging if requested.  */
+#if YYDEBUG
+
+# ifndef YYFPRINTF
+#  include <stdio.h> /* INFRINGES ON USER NAME SPACE */
+#  define YYFPRINTF fprintf
+# endif
+
+# define YYDPRINTF(Args)                        \
+do {                                            \
+  if (yydebug)                                  \
+    YYFPRINTF Args;                             \
+} while (0)
+
+
+
+
+# define YY_SYMBOL_PRINT(Title, Kind, Value, Location)                    \
+do {                                                                      \
+  if (yydebug)                                                            \
+    {                                                                     \
+      YYFPRINTF (stderr, "%s ", Title);                                   \
+      yy_symbol_print (stderr,                                            \
+                  Kind, Value); \
+      YYFPRINTF (stderr, "\n");                                           \
+    }                                                                     \
+} while (0)
+
+
+/*-----------------------------------.
+| Print this symbol's value on YYO.  |
+`-----------------------------------*/
+
+static void
+yy_symbol_value_print (FILE *yyo,
+                       yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep)
+{
+  FILE *yyoutput = yyo;
+  YY_USE (yyoutput);
+  if (!yyvaluep)
+    return;
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  YY_USE (yykind);
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+}
+
+
+/*---------------------------.
+| Print this symbol on YYO.  |
+`---------------------------*/
+
+static void
+yy_symbol_print (FILE *yyo,
+                 yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep)
+{
+  YYFPRINTF (yyo, "%s %s (",
+             yykind < YYNTOKENS ? "token" : "nterm", yysymbol_name (yykind));
+
+  yy_symbol_value_print (yyo, yykind, yyvaluep);
+  YYFPRINTF (yyo, ")");
+}
+
+/*------------------------------------------------------------------.
+| yy_stack_print -- Print the state stack from its BOTTOM up to its |
+| TOP (included).                                                   |
+`------------------------------------------------------------------*/
+
+static void
+yy_stack_print (yy_state_t *yybottom, yy_state_t *yytop)
+{
+  YYFPRINTF (stderr, "Stack now");
+  for (; yybottom <= yytop; yybottom++)
+    {
+      int yybot = *yybottom;
+      YYFPRINTF (stderr, " %d", yybot);
+    }
+  YYFPRINTF (stderr, "\n");
+}
+
+# define YY_STACK_PRINT(Bottom, Top)                            \
+do {                                                            \
+  if (yydebug)                                                  \
+    yy_stack_print ((Bottom), (Top));                           \
+} while (0)
+
+
+/*------------------------------------------------.
+| Report that the YYRULE is going to be reduced.  |
+`------------------------------------------------*/
+
+static void
+yy_reduce_print (yy_state_t *yyssp, YYSTYPE *yyvsp,
+                 int yyrule)
+{
+  int yylno = yyrline[yyrule];
+  int yynrhs = yyr2[yyrule];
+  int yyi;
+  YYFPRINTF (stderr, "Reducing stack by rule %d (line %d):\n",
+             yyrule - 1, yylno);
+  /* The symbols being reduced.  */
+  for (yyi = 0; yyi < yynrhs; yyi++)
+    {
+      YYFPRINTF (stderr, "   $%d = ", yyi + 1);
+      yy_symbol_print (stderr,
+                       YY_ACCESSING_SYMBOL (+yyssp[yyi + 1 - yynrhs]),
+                       &yyvsp[(yyi + 1) - (yynrhs)]);
+      YYFPRINTF (stderr, "\n");
+    }
+}
+
+# define YY_REDUCE_PRINT(Rule)          \
+do {                                    \
+  if (yydebug)                          \
+    yy_reduce_print (yyssp, yyvsp, Rule); \
+} while (0)
+
+/* Nonzero means print parse trace.  It is left uninitialized so that
+   multiple parsers can coexist.  */
+int yydebug;
+#else /* !YYDEBUG */
+# define YYDPRINTF(Args) ((void) 0)
+# define YY_SYMBOL_PRINT(Title, Kind, Value, Location)
+# define YY_STACK_PRINT(Bottom, Top)
+# define YY_REDUCE_PRINT(Rule)
+#endif /* !YYDEBUG */
+
+
+/* YYINITDEPTH -- initial size of the parser's stacks.  */
+#ifndef YYINITDEPTH
+# define YYINITDEPTH 200
+#endif
+
+/* YYMAXDEPTH -- maximum size the stacks can grow to (effective only
+   if the built-in stack extension method is used).
+
+   Do not make this value too large; the results are undefined if
+   YYSTACK_ALLOC_MAXIMUM < YYSTACK_BYTES (YYMAXDEPTH)
+   evaluated with infinite-precision integer arithmetic.  */
+
+#ifndef YYMAXDEPTH
+# define YYMAXDEPTH 10000
+#endif
+
+
+
+
+
+
+/*-----------------------------------------------.
+| Release the memory associated to this symbol.  |
+`-----------------------------------------------*/
+
+static void
+yydestruct (const char *yymsg,
+            yysymbol_kind_t yykind, YYSTYPE *yyvaluep)
+{
+  YY_USE (yyvaluep);
+  if (!yymsg)
+    yymsg = "Deleting";
+  YY_SYMBOL_PRINT (yymsg, yykind, yyvaluep, yylocationp);
+
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  YY_USE (yykind);
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+}
+
+
+/* Lookahead token kind.  */
+int yychar;
+
+/* The semantic value of the lookahead symbol.  */
+YYSTYPE yylval;
+/* Number of syntax errors so far.  */
+int yynerrs;
+
+
+
+
+/*----------.
+| yyparse.  |
+`----------*/
+
+int
+yyparse (void)
+{
+    yy_state_fast_t yystate = 0;
+    /* Number of tokens to shift before error messages enabled.  */
+    int yyerrstatus = 0;
+
+    /* Refer to the stacks through separate pointers, to allow yyoverflow
+       to reallocate them elsewhere.  */
+
+    /* Their size.  */
+    YYPTRDIFF_T yystacksize = YYINITDEPTH;
+
+    /* The state stack: array, bottom, top.  */
+    yy_state_t yyssa[YYINITDEPTH];
+    yy_state_t *yyss = yyssa;
+    yy_state_t *yyssp = yyss;
+
+    /* The semantic value stack: array, bottom, top.  */
+    YYSTYPE yyvsa[YYINITDEPTH];
+    YYSTYPE *yyvs = yyvsa;
+    YYSTYPE *yyvsp = yyvs;
+
+  int yyn;
+  /* The return value of yyparse.  */
+  int yyresult;
+  /* Lookahead symbol kind.  */
+  yysymbol_kind_t yytoken = YYSYMBOL_YYEMPTY;
+  /* The variables used to return semantic value and location from the
+     action routines.  */
+  YYSTYPE yyval;
+
+
+
+#define YYPOPSTACK(N)   (yyvsp -= (N), yyssp -= (N))
+
+  /* The number of symbols on the RHS of the reduced rule.
+     Keep to zero when no symbol should be popped.  */
+  int yylen = 0;
+
+  YYDPRINTF ((stderr, "Starting parse\n"));
+
+  yychar = YYEMPTY; /* Cause a token to be read.  */
+
+  goto yysetstate;
+
+
+/*------------------------------------------------------------.
+| yynewstate -- push a new state, which is found in yystate.  |
+`------------------------------------------------------------*/
+yynewstate:
+  /* In all cases, when you get here, the value and location stacks
+     have just been pushed.  So pushing a state here evens the stacks.  */
+  yyssp++;
+
+
+/*--------------------------------------------------------------------.
+| yysetstate -- set current state (the top of the stack) to yystate.  |
+`--------------------------------------------------------------------*/
+yysetstate:
+  YYDPRINTF ((stderr, "Entering state %d\n", yystate));
+  YY_ASSERT (0 <= yystate && yystate < YYNSTATES);
+  YY_IGNORE_USELESS_CAST_BEGIN
+  *yyssp = YY_CAST (yy_state_t, yystate);
+  YY_IGNORE_USELESS_CAST_END
+  YY_STACK_PRINT (yyss, yyssp);
+
+  if (yyss + yystacksize - 1 <= yyssp)
+#if !defined yyoverflow && !defined YYSTACK_RELOCATE
+    YYNOMEM;
+#else
+    {
+      /* Get the current used size of the three stacks, in elements.  */
+      YYPTRDIFF_T yysize = yyssp - yyss + 1;
+
+# if defined yyoverflow
+      {
+        /* Give user a chance to reallocate the stack.  Use copies of
+           these so that the &'s don't force the real ones into
+           memory.  */
+        yy_state_t *yyss1 = yyss;
+        YYSTYPE *yyvs1 = yyvs;
+
+        /* Each stack pointer address is followed by the size of the
+           data in use in that stack, in bytes.  This used to be a
+           conditional around just the two extra args, but that might
+           be undefined if yyoverflow is a macro.  */
+        yyoverflow (YY_("memory exhausted"),
+                    &yyss1, yysize * YYSIZEOF (*yyssp),
+                    &yyvs1, yysize * YYSIZEOF (*yyvsp),
+                    &yystacksize);
+        yyss = yyss1;
+        yyvs = yyvs1;
+      }
+# else /* defined YYSTACK_RELOCATE */
+      /* Extend the stack our own way.  */
+      if (YYMAXDEPTH <= yystacksize)
+        YYNOMEM;
+      yystacksize *= 2;
+      if (YYMAXDEPTH < yystacksize)
+        yystacksize = YYMAXDEPTH;
+
+      {
+        yy_state_t *yyss1 = yyss;
+        union yyalloc *yyptr =
+          YY_CAST (union yyalloc *,
+                   YYSTACK_ALLOC (YY_CAST (YYSIZE_T, YYSTACK_BYTES (yystacksize))));
+        if (! yyptr)
+          YYNOMEM;
+        YYSTACK_RELOCATE (yyss_alloc, yyss);
+        YYSTACK_RELOCATE (yyvs_alloc, yyvs);
+#  undef YYSTACK_RELOCATE
+        if (yyss1 != yyssa)
+          YYSTACK_FREE (yyss1);
+      }
+# endif
+
+      yyssp = yyss + yysize - 1;
+      yyvsp = yyvs + yysize - 1;
+
+      YY_IGNORE_USELESS_CAST_BEGIN
+      YYDPRINTF ((stderr, "Stack size increased to %ld\n",
+                  YY_CAST (long, yystacksize)));
+      YY_IGNORE_USELESS_CAST_END
+
+      if (yyss + yystacksize - 1 <= yyssp)
+        YYABORT;
+    }
+#endif /* !defined yyoverflow && !defined YYSTACK_RELOCATE */
+
+
+  if (yystate == YYFINAL)
+    YYACCEPT;
+
+  goto yybackup;
+
+
+/*-----------.
+| yybackup.  |
+`-----------*/
+yybackup:
+  /* Do appropriate processing given the current state.  Read a
+     lookahead token if we need one and don't already have one.  */
+
+  /* First try to decide what to do without reference to lookahead token.  */
+  yyn = yypact[yystate];
+  if (yypact_value_is_default (yyn))
+    goto yydefault;
+
+  /* Not known => get a lookahead token if don't already have one.  */
+
+  /* YYCHAR is either empty, or end-of-input, or a valid lookahead.  */
+  if (yychar == YYEMPTY)
+    {
+      YYDPRINTF ((stderr, "Reading a token\n"));
+      yychar = yylex ();
+    }
+
+  if (yychar <= YYEOF)
+    {
+      yychar = YYEOF;
+      yytoken = YYSYMBOL_YYEOF;
+      YYDPRINTF ((stderr, "Now at end of input.\n"));
+    }
+  else if (yychar == YYerror)
+    {
+      /* The scanner already issued an error message, process directly
+         to error recovery.  But do not keep the error token as
+         lookahead, it is too special and may lead us to an endless
+         loop in error recovery. */
+      yychar = YYUNDEF;
+      yytoken = YYSYMBOL_YYerror;
+      goto yyerrlab1;
+    }
+  else
+    {
+      yytoken = YYTRANSLATE (yychar);
+      YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
+    }
+
+  /* If the proper action on seeing token YYTOKEN is to reduce or to
+     detect an error, take that action.  */
+  yyn += yytoken;
+  if (yyn < 0 || YYLAST < yyn || yycheck[yyn] != yytoken)
+    goto yydefault;
+  yyn = yytable[yyn];
+  if (yyn <= 0)
+    {
+      if (yytable_value_is_error (yyn))
+        goto yyerrlab;
+      yyn = -yyn;
+      goto yyreduce;
+    }
+
+  /* Count tokens shifted since error; after three, turn off error
+     status.  */
+  if (yyerrstatus)
+    yyerrstatus--;
+
+  /* Shift the lookahead token.  */
+  YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
+  yystate = yyn;
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  *++yyvsp = yylval;
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+
+  /* Discard the shifted token.  */
+  yychar = YYEMPTY;
+  goto yynewstate;
+
+
+/*-----------------------------------------------------------.
+| yydefault -- do the default action for the current state.  |
+`-----------------------------------------------------------*/
+yydefault:
+  yyn = yydefact[yystate];
+  if (yyn == 0)
+    goto yyerrlab;
+  goto yyreduce;
+
+
+/*-----------------------------.
+| yyreduce -- do a reduction.  |
+`-----------------------------*/
+yyreduce:
+  /* yyn is the number of a rule to reduce with.  */
+  yylen = yyr2[yyn];
+
+  /* If YYLEN is nonzero, implement the default value of the action:
+     '$$ = $1'.
+
+     Otherwise, the following line sets YYVAL to garbage.
+     This behavior is undocumented and Bison
+     users should not rely upon it.  Assigning to YYVAL
+     unconditionally makes the parser a bit smaller, and it avoids a
+     GCC warning that YYVAL may be used uninitialized.  */
+  yyval = yyvsp[1-yylen];
+
+
+  YY_REDUCE_PRINT (yyn);
+  switch (yyn)
+    {
+  case 4: /* item: time  */
+#line 197 "getdate.y"
+               {
+	    yyHaveTime++;
+	}
+#line 1364 "getdate.c"
+    break;
+
+  case 5: /* item: zone  */
+#line 200 "getdate.y"
+               {
+	    yyHaveZone++;
+	}
+#line 1372 "getdate.c"
+    break;
+
+  case 6: /* item: date  */
+#line 203 "getdate.y"
+               {
+	    yyHaveDate++;
+	}
+#line 1380 "getdate.c"
+    break;
+
+  case 7: /* item: day  */
+#line 206 "getdate.y"
+              {
+	    yyHaveDay++;
+	}
+#line 1388 "getdate.c"
+    break;
+
+  case 8: /* item: rel  */
+#line 209 "getdate.y"
+              {
+	    yyHaveRel++;
+	}
+#line 1396 "getdate.c"
+    break;
+
+  case 10: /* time: tUNUMBER tMERIDIAN  */
+#line 215 "getdate.y"
+                             {
+	    yyHour = (yyvsp[-1].Number);
+	    yyMinutes = 0;
+	    yySeconds = 0;
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1407 "getdate.c"
+    break;
+
+  case 11: /* time: tUNUMBER ':' tUNUMBER o_merid  */
+#line 221 "getdate.y"
+                                        {
+	    yyHour = (yyvsp[-3].Number);
+	    yyMinutes = (yyvsp[-1].Number);
+	    yySeconds = 0;
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1418 "getdate.c"
+    break;
+
+  case 12: /* time: tUNUMBER ':' tUNUMBER tSNUMBER  */
+#line 227 "getdate.y"
+                                         {
+	    yyHour = (yyvsp[-3].Number);
+	    yyMinutes = (yyvsp[-1].Number);
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ((yyvsp[0].Number) < 0
+			  ? -(yyvsp[0].Number) % 100 + (-(yyvsp[0].Number) / 100) * 60
+			  : - ((yyvsp[0].Number) % 100 + ((yyvsp[0].Number) / 100) * 60));
+	}
+#line 1432 "getdate.c"
+    break;
+
+  case 13: /* time: tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid  */
+#line 236 "getdate.y"
+                                                     {
+	    yyHour = (yyvsp[-5].Number);
+	    yyMinutes = (yyvsp[-3].Number);
+	    yySeconds = (yyvsp[-1].Number);
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1443 "getdate.c"
+    break;
+
+  case 14: /* time: tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER  */
+#line 242 "getdate.y"
+                                                      {
+	    yyHour = (yyvsp[-5].Number);
+	    yyMinutes = (yyvsp[-3].Number);
+	    yySeconds = (yyvsp[-1].Number);
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ((yyvsp[0].Number) < 0
+			  ? -(yyvsp[0].Number) % 100 + (-(yyvsp[0].Number) / 100) * 60
+			  : - ((yyvsp[0].Number) % 100 + ((yyvsp[0].Number) / 100) * 60));
+	}
+#line 1458 "getdate.c"
+    break;
+
+  case 15: /* zone: tZONE  */
+#line 254 "getdate.y"
+                {
+	    yyTimezone = (yyvsp[0].Number);
+	}
+#line 1466 "getdate.c"
+    break;
+
+  case 16: /* zone: tDAYZONE  */
+#line 257 "getdate.y"
+                   {
+	    yyTimezone = (yyvsp[0].Number) - 60;
+	}
+#line 1474 "getdate.c"
+    break;
+
+  case 17: /* zone: tZONE tDST  */
+#line 261 "getdate.y"
+                     {
+	    yyTimezone = (yyvsp[-1].Number) - 60;
+	}
+#line 1482 "getdate.c"
+    break;
+
+  case 18: /* day: tDAY  */
+#line 266 "getdate.y"
+               {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = (yyvsp[0].Number);
+	}
+#line 1491 "getdate.c"
+    break;
+
+  case 19: /* day: tDAY ','  */
+#line 270 "getdate.y"
+                   {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = (yyvsp[-1].Number);
+	}
+#line 1500 "getdate.c"
+    break;
+
+  case 20: /* day: tUNUMBER tDAY  */
+#line 274 "getdate.y"
+                        {
+	    yyDayOrdinal = (yyvsp[-1].Number);
+	    yyDayNumber = (yyvsp[0].Number);
+	}
+#line 1509 "getdate.c"
+    break;
+
+  case 21: /* date: tUNUMBER '/' tUNUMBER  */
+#line 280 "getdate.y"
+                                {
+	    yyMonth = (yyvsp[-2].Number);
+	    yyDay = (yyvsp[0].Number);
+	}
+#line 1518 "getdate.c"
+    break;
+
+  case 22: /* date: tUNUMBER '/' tUNUMBER '/' tUNUMBER  */
+#line 284 "getdate.y"
+                                             {
+	  /* Interpret as YYYY/MM/DD if $1 >= 1000, otherwise as MM/DD/YY.
+	     The goal in recognizing YYYY/MM/DD is solely to support legacy
+	     machine-generated dates like those in an RCS log listing.  If
+	     you want portability, use the ISO 8601 format.  */
+	  if ((yyvsp[-4].Number) >= 1000)
+	    {
+	      yyYear = (yyvsp[-4].Number);
+	      yyMonth = (yyvsp[-2].Number);
+	      yyDay = (yyvsp[0].Number);
+	    }
+	  else
+	    {
+	      yyMonth = (yyvsp[-4].Number);
+	      yyDay = (yyvsp[-2].Number);
+	      yyYear = (yyvsp[0].Number);
+	    }
+	}
+#line 1541 "getdate.c"
+    break;
+
+  case 23: /* date: tUNUMBER tSNUMBER tSNUMBER  */
+#line 302 "getdate.y"
+                                     {
+	    /* ISO 8601 format.  yyyy-mm-dd.  */
+	    yyYear = (yyvsp[-2].Number);
+	    yyMonth = -(yyvsp[-1].Number);
+	    yyDay = -(yyvsp[0].Number);
+	}
+#line 1552 "getdate.c"
+    break;
+
+  case 24: /* date: tUNUMBER tMONTH tSNUMBER  */
+#line 308 "getdate.y"
+                                   {
+	    /* e.g. 17-JUN-1992.  */
+	    yyDay = (yyvsp[-2].Number);
+	    yyMonth = (yyvsp[-1].Number);
+	    yyYear = -(yyvsp[0].Number);
+	}
+#line 1563 "getdate.c"
+    break;
+
+  case 25: /* date: tMONTH tUNUMBER  */
+#line 314 "getdate.y"
+                          {
+	    yyMonth = (yyvsp[-1].Number);
+	    yyDay = (yyvsp[0].Number);
+	}
+#line 1572 "getdate.c"
+    break;
+
+  case 26: /* date: tMONTH tUNUMBER ',' tUNUMBER  */
+#line 318 "getdate.y"
+                                       {
+	    yyMonth = (yyvsp[-3].Number);
+	    yyDay = (yyvsp[-2].Number);
+	    yyYear = (yyvsp[0].Number);
+	}
+#line 1582 "getdate.c"
+    break;
+
+  case 27: /* date: tUNUMBER tMONTH  */
+#line 323 "getdate.y"
+                          {
+	    yyMonth = (yyvsp[0].Number);
+	    yyDay = (yyvsp[-1].Number);
+	}
+#line 1591 "getdate.c"
+    break;
+
+  case 28: /* date: tUNUMBER tMONTH tUNUMBER  */
+#line 327 "getdate.y"
+                                   {
+	    yyMonth = (yyvsp[-1].Number);
+	    yyDay = (yyvsp[-2].Number);
+	    yyYear = (yyvsp[0].Number);
+	}
+#line 1601 "getdate.c"
+    break;
+
+  case 29: /* rel: relunit tAGO  */
+#line 334 "getdate.y"
+                       {
+	    yyRelSeconds = -yyRelSeconds;
+	    yyRelMinutes = -yyRelMinutes;
+	    yyRelHour = -yyRelHour;
+	    yyRelDay = -yyRelDay;
+	    yyRelMonth = -yyRelMonth;
+	    yyRelYear = -yyRelYear;
+	}
+#line 1614 "getdate.c"
+    break;
+
+  case 31: /* relunit: tUNUMBER tYEAR_UNIT  */
+#line 345 "getdate.y"
+                              {
+	    yyRelYear += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1622 "getdate.c"
+    break;
+
+  case 32: /* relunit: tSNUMBER tYEAR_UNIT  */
+#line 348 "getdate.y"
+                              {
+	    yyRelYear += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1630 "getdate.c"
+    break;
+
+  case 33: /* relunit: tYEAR_UNIT  */
+#line 351 "getdate.y"
+                     {
+	    yyRelYear += (yyvsp[0].Number);
+	}
+#line 1638 "getdate.c"
+    break;
+
+  case 34: /* relunit: tUNUMBER tMONTH_UNIT  */
+#line 354 "getdate.y"
+                               {
+	    yyRelMonth += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1646 "getdate.c"
+    break;
+
+  case 35: /* relunit: tSNUMBER tMONTH_UNIT  */
+#line 357 "getdate.y"
+                               {
+	    yyRelMonth += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1654 "getdate.c"
+    break;
+
+  case 36: /* relunit: tMONTH_UNIT  */
+#line 360 "getdate.y"
+                      {
+	    yyRelMonth += (yyvsp[0].Number);
+	}
+#line 1662 "getdate.c"
+    break;
+
+  case 37: /* relunit: tUNUMBER tDAY_UNIT  */
+#line 363 "getdate.y"
+                             {
+	    yyRelDay += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1670 "getdate.c"
+    break;
+
+  case 38: /* relunit: tSNUMBER tDAY_UNIT  */
+#line 366 "getdate.y"
+                             {
+	    yyRelDay += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1678 "getdate.c"
+    break;
+
+  case 39: /* relunit: tDAY_UNIT  */
+#line 369 "getdate.y"
+                    {
+	    yyRelDay += (yyvsp[0].Number);
+	}
+#line 1686 "getdate.c"
+    break;
+
+  case 40: /* relunit: tUNUMBER tHOUR_UNIT  */
+#line 372 "getdate.y"
+                              {
+	    yyRelHour += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1694 "getdate.c"
+    break;
+
+  case 41: /* relunit: tSNUMBER tHOUR_UNIT  */
+#line 375 "getdate.y"
+                              {
+	    yyRelHour += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1702 "getdate.c"
+    break;
+
+  case 42: /* relunit: tHOUR_UNIT  */
+#line 378 "getdate.y"
+                     {
+	    yyRelHour += (yyvsp[0].Number);
+	}
+#line 1710 "getdate.c"
+    break;
+
+  case 43: /* relunit: tUNUMBER tMINUTE_UNIT  */
+#line 381 "getdate.y"
+                                {
+	    yyRelMinutes += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1718 "getdate.c"
+    break;
+
+  case 44: /* relunit: tSNUMBER tMINUTE_UNIT  */
+#line 384 "getdate.y"
+                                {
+	    yyRelMinutes += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1726 "getdate.c"
+    break;
+
+  case 45: /* relunit: tMINUTE_UNIT  */
+#line 387 "getdate.y"
+                       {
+	    yyRelMinutes += (yyvsp[0].Number);
+	}
+#line 1734 "getdate.c"
+    break;
+
+  case 46: /* relunit: tUNUMBER tSEC_UNIT  */
+#line 390 "getdate.y"
+                             {
+	    yyRelSeconds += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1742 "getdate.c"
+    break;
+
+  case 47: /* relunit: tSNUMBER tSEC_UNIT  */
+#line 393 "getdate.y"
+                             {
+	    yyRelSeconds += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1750 "getdate.c"
+    break;
+
+  case 48: /* relunit: tSEC_UNIT  */
+#line 396 "getdate.y"
+                    {
+	    yyRelSeconds += (yyvsp[0].Number);
+	}
+#line 1758 "getdate.c"
+    break;
+
+  case 49: /* number: tUNUMBER  */
+#line 402 "getdate.y"
+          {
+	    if (yyHaveTime && yyHaveDate && !yyHaveRel)
+	      yyYear = (yyvsp[0].Number);
+	    else
+	      {
+		if ((yyvsp[0].Number)>10000)
+		  {
+		    yyHaveDate++;
+		    yyDay= ((yyvsp[0].Number))%100;
+		    yyMonth= ((yyvsp[0].Number)/100)%100;
+		    yyYear = (yyvsp[0].Number)/10000;
+		  }
+		else
+		  {
+		    yyHaveTime++;
+		    if ((yyvsp[0].Number) < 100)
+		      {
+			yyHour = (yyvsp[0].Number);
+			yyMinutes = 0;
+		      }
+		    else
+		      {
+		    	yyHour = (yyvsp[0].Number) / 100;
+		    	yyMinutes = (yyvsp[0].Number) % 100;
+		      }
+		    yySeconds = 0;
+		    yyMeridian = MER24;
+		  }
+	      }
+	  }
+#line 1793 "getdate.c"
+    break;
+
+  case 50: /* o_merid: %empty  */
+#line 435 "getdate.y"
+          {
+	    (yyval.Meridian) = MER24;
+	  }
+#line 1801 "getdate.c"
+    break;
+
+  case 51: /* o_merid: tMERIDIAN  */
+#line 439 "getdate.y"
+          {
+	    (yyval.Meridian) = (yyvsp[0].Meridian);
+	  }
+#line 1809 "getdate.c"
+    break;
+
+
+#line 1813 "getdate.c"
+
+      default: break;
+    }
+  /* User semantic actions sometimes alter yychar, and that requires
+     that yytoken be updated with the new translation.  We take the
+     approach of translating immediately before every use of yytoken.
+     One alternative is translating here after every semantic action,
+     but that translation would be missed if the semantic action invokes
+     YYABORT, YYACCEPT, or YYERROR immediately after altering yychar or
+     if it invokes YYBACKUP.  In the case of YYABORT or YYACCEPT, an
+     incorrect destructor might then be invoked immediately.  In the
+     case of YYERROR or YYBACKUP, subsequent parser actions might lead
+     to an incorrect destructor call or verbose syntax error message
+     before the lookahead is translated.  */
+  YY_SYMBOL_PRINT ("-> $$ =", YY_CAST (yysymbol_kind_t, yyr1[yyn]), &yyval, &yyloc);
+
+  YYPOPSTACK (yylen);
+  yylen = 0;
+
+  *++yyvsp = yyval;
+
+  /* Now 'shift' the result of the reduction.  Determine what state
+     that goes to, based on the state we popped back to and the rule
+     number reduced by.  */
+  {
+    const int yylhs = yyr1[yyn] - YYNTOKENS;
+    const int yyi = yypgoto[yylhs] + *yyssp;
+    yystate = (0 <= yyi && yyi <= YYLAST && yycheck[yyi] == *yyssp
+               ? yytable[yyi]
+               : yydefgoto[yylhs]);
+  }
+
+  goto yynewstate;
+
+
+/*--------------------------------------.
+| yyerrlab -- here on detecting error.  |
+`--------------------------------------*/
+yyerrlab:
+  /* Make sure we have latest lookahead translation.  See comments at
+     user semantic actions for why this is necessary.  */
+  yytoken = yychar == YYEMPTY ? YYSYMBOL_YYEMPTY : YYTRANSLATE (yychar);
+  /* If not already recovering from an error, report this error.  */
+  if (!yyerrstatus)
+    {
+      ++yynerrs;
+      yyerror (YY_("syntax error"));
+    }
+
+  if (yyerrstatus == 3)
+    {
+      /* If just tried and failed to reuse lookahead token after an
+         error, discard it.  */
+
+      if (yychar <= YYEOF)
+        {
+          /* Return failure if at end of input.  */
+          if (yychar == YYEOF)
+            YYABORT;
+        }
+      else
+        {
+          yydestruct ("Error: discarding",
+                      yytoken, &yylval);
+          yychar = YYEMPTY;
+        }
+    }
+
+  /* Else will try to reuse lookahead token after shifting the error
+     token.  */
+  goto yyerrlab1;
+
+
+/*---------------------------------------------------.
+| yyerrorlab -- error raised explicitly by YYERROR.  |
+`---------------------------------------------------*/
+yyerrorlab:
+  /* Pacify compilers when the user code never invokes YYERROR and the
+     label yyerrorlab therefore never appears in user code.  */
+  if (0)
+    YYERROR;
+  ++yynerrs;
+
+  /* Do not reclaim the symbols of the rule whose action triggered
+     this YYERROR.  */
+  YYPOPSTACK (yylen);
+  yylen = 0;
+  YY_STACK_PRINT (yyss, yyssp);
+  yystate = *yyssp;
+  goto yyerrlab1;
+
+
+/*-------------------------------------------------------------.
+| yyerrlab1 -- common code for both syntax error and YYERROR.  |
+`-------------------------------------------------------------*/
+yyerrlab1:
+  yyerrstatus = 3;      /* Each real token shifted decrements this.  */
+
+  /* Pop stack until we find a state that shifts the error token.  */
+  for (;;)
+    {
+      yyn = yypact[yystate];
+      if (!yypact_value_is_default (yyn))
+        {
+          yyn += YYSYMBOL_YYerror;
+          if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == YYSYMBOL_YYerror)
+            {
+              yyn = yytable[yyn];
+              if (0 < yyn)
+                break;
+            }
+        }
+
+      /* Pop the current state because it cannot handle the error token.  */
+      if (yyssp == yyss)
+        YYABORT;
+
+
+      yydestruct ("Error: popping",
+                  YY_ACCESSING_SYMBOL (yystate), yyvsp);
+      YYPOPSTACK (1);
+      yystate = *yyssp;
+      YY_STACK_PRINT (yyss, yyssp);
+    }
+
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  *++yyvsp = yylval;
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+
+
+  /* Shift the error token.  */
+  YY_SYMBOL_PRINT ("Shifting", YY_ACCESSING_SYMBOL (yyn), yyvsp, yylsp);
+
+  yystate = yyn;
+  goto yynewstate;
+
+
+/*-------------------------------------.
+| yyacceptlab -- YYACCEPT comes here.  |
+`-------------------------------------*/
+yyacceptlab:
+  yyresult = 0;
+  goto yyreturnlab;
+
+
+/*-----------------------------------.
+| yyabortlab -- YYABORT comes here.  |
+`-----------------------------------*/
+yyabortlab:
+  yyresult = 1;
+  goto yyreturnlab;
+
+
+/*-----------------------------------------------------------.
+| yyexhaustedlab -- YYNOMEM (memory exhaustion) comes here.  |
+`-----------------------------------------------------------*/
+yyexhaustedlab:
+  yyerror (YY_("memory exhausted"));
+  yyresult = 2;
+  goto yyreturnlab;
+
+
+/*----------------------------------------------------------.
+| yyreturnlab -- parsing is finished, clean up and return.  |
+`----------------------------------------------------------*/
+yyreturnlab:
+  if (yychar != YYEMPTY)
+    {
+      /* Make sure we have latest lookahead translation.  See comments at
+         user semantic actions for why this is necessary.  */
+      yytoken = YYTRANSLATE (yychar);
+      yydestruct ("Cleanup: discarding lookahead",
+                  yytoken, &yylval);
+    }
+  /* Do not reclaim the symbols of the rule whose action triggered
+     this YYABORT or YYACCEPT.  */
+  YYPOPSTACK (yylen);
+  YY_STACK_PRINT (yyss, yyssp);
+  while (yyssp != yyss)
+    {
+      yydestruct ("Cleanup: popping",
+                  YY_ACCESSING_SYMBOL (+*yyssp), yyvsp);
+      YYPOPSTACK (1);
+    }
+#ifndef yyoverflow
+  if (yyss != yyssa)
+    YYSTACK_FREE (yyss);
+#endif
+
+  return yyresult;
+}
+
+#line 444 "getdate.y"
+
+
+/* Include this file down here because bison inserts code above which
+   may define-away `const'.  We want the prototype for get_date to have
+   the same signature as the function definition does. */
+#include "getdate.h"
+
+extern struct tm	*gmtime ();
+extern struct tm	*localtime ();
+extern time_t		mktime ();
+
+/* Month and day table. */
+static TABLE const MonthDayTable[] = {
+    { "january",	tMONTH,  1 },
+    { "february",	tMONTH,  2 },
+    { "march",		tMONTH,  3 },
+    { "april",		tMONTH,  4 },
+    { "may",		tMONTH,  5 },
+    { "june",		tMONTH,  6 },
+    { "july",		tMONTH,  7 },
+    { "august",		tMONTH,  8 },
+    { "september",	tMONTH,  9 },
+    { "sept",		tMONTH,  9 },
+    { "october",	tMONTH, 10 },
+    { "november",	tMONTH, 11 },
+    { "december",	tMONTH, 12 },
+    { "sunday",		tDAY, 0 },
+    { "monday",		tDAY, 1 },
+    { "tuesday",	tDAY, 2 },
+    { "tues",		tDAY, 2 },
+    { "wednesday",	tDAY, 3 },
+    { "wednes",		tDAY, 3 },
+    { "thursday",	tDAY, 4 },
+    { "thur",		tDAY, 4 },
+    { "thurs",		tDAY, 4 },
+    { "friday",		tDAY, 5 },
+    { "saturday",	tDAY, 6 },
+    { NULL, 0, 0 }
+};
+
+/* Time units table. */
+static TABLE const UnitsTable[] = {
+    { "year",		tYEAR_UNIT,	1 },
+    { "month",		tMONTH_UNIT,	1 },
+    { "fortnight",	tDAY_UNIT,	14 },
+    { "week",		tDAY_UNIT,	7 },
+    { "day",		tDAY_UNIT,	1 },
+    { "hour",		tHOUR_UNIT,	1 },
+    { "minute",		tMINUTE_UNIT,	1 },
+    { "min",		tMINUTE_UNIT,	1 },
+    { "second",		tSEC_UNIT,	1 },
+    { "sec",		tSEC_UNIT,	1 },
+    { NULL, 0, 0 }
+};
+
+/* Assorted relative-time words. */
+static TABLE const OtherTable[] = {
+    { "tomorrow",	tMINUTE_UNIT,	1 * 24 * 60 },
+    { "yesterday",	tMINUTE_UNIT,	-1 * 24 * 60 },
+    { "today",		tMINUTE_UNIT,	0 },
+    { "now",		tMINUTE_UNIT,	0 },
+    { "last",		tUNUMBER,	-1 },
+    { "this",		tMINUTE_UNIT,	0 },
+    { "next",		tUNUMBER,	1 },
+    { "first",		tUNUMBER,	1 },
+/*  { "second",		tUNUMBER,	2 }, */
+    { "third",		tUNUMBER,	3 },
+    { "fourth",		tUNUMBER,	4 },
+    { "fifth",		tUNUMBER,	5 },
+    { "sixth",		tUNUMBER,	6 },
+    { "seventh",	tUNUMBER,	7 },
+    { "eighth",		tUNUMBER,	8 },
+    { "ninth",		tUNUMBER,	9 },
+    { "tenth",		tUNUMBER,	10 },
+    { "eleventh",	tUNUMBER,	11 },
+    { "twelfth",	tUNUMBER,	12 },
+    { "ago",		tAGO,	1 },
+    { NULL, 0, 0 }
+};
+
+/* The timezone table. */
+static TABLE const TimezoneTable[] = {
+    { "gmt",	tZONE,     HOUR ( 0) },	/* Greenwich Mean */
+    { "ut",	tZONE,     HOUR ( 0) },	/* Universal (Coordinated) */
+    { "utc",	tZONE,     HOUR ( 0) },
+    { "wet",	tZONE,     HOUR ( 0) },	/* Western European */
+    { "bst",	tDAYZONE,  HOUR ( 0) },	/* British Summer */
+    { "wat",	tZONE,     HOUR ( 1) },	/* West Africa */
+    { "at",	tZONE,     HOUR ( 2) },	/* Azores */
+#if	0
+    /* For completeness.  BST is also British Summer, and GST is
+     * also Guam Standard. */
+    { "bst",	tZONE,     HOUR ( 3) },	/* Brazil Standard */
+    { "gst",	tZONE,     HOUR ( 3) },	/* Greenland Standard */
+#endif
+#if 0
+    { "nft",	tZONE,     HOUR (3.5) },	/* Newfoundland */
+    { "nst",	tZONE,     HOUR (3.5) },	/* Newfoundland Standard */
+    { "ndt",	tDAYZONE,  HOUR (3.5) },	/* Newfoundland Daylight */
+#endif
+    { "ast",	tZONE,     HOUR ( 4) },	/* Atlantic Standard */
+    { "adt",	tDAYZONE,  HOUR ( 4) },	/* Atlantic Daylight */
+    { "est",	tZONE,     HOUR ( 5) },	/* Eastern Standard */
+    { "edt",	tDAYZONE,  HOUR ( 5) },	/* Eastern Daylight */
+    { "cst",	tZONE,     HOUR ( 6) },	/* Central Standard */
+    { "cdt",	tDAYZONE,  HOUR ( 6) },	/* Central Daylight */
+    { "mst",	tZONE,     HOUR ( 7) },	/* Mountain Standard */
+    { "mdt",	tDAYZONE,  HOUR ( 7) },	/* Mountain Daylight */
+    { "pst",	tZONE,     HOUR ( 8) },	/* Pacific Standard */
+    { "pdt",	tDAYZONE,  HOUR ( 8) },	/* Pacific Daylight */
+    { "yst",	tZONE,     HOUR ( 9) },	/* Yukon Standard */
+    { "ydt",	tDAYZONE,  HOUR ( 9) },	/* Yukon Daylight */
+    { "hst",	tZONE,     HOUR (10) },	/* Hawaii Standard */
+    { "hdt",	tDAYZONE,  HOUR (10) },	/* Hawaii Daylight */
+    { "cat",	tZONE,     HOUR (10) },	/* Central Alaska */
+    { "ahst",	tZONE,     HOUR (10) },	/* Alaska-Hawaii Standard */
+    { "nt",	tZONE,     HOUR (11) },	/* Nome */
+    { "idlw",	tZONE,     HOUR (12) },	/* International Date Line West */
+    { "cet",	tZONE,     -HOUR (1) },	/* Central European */
+    { "met",	tZONE,     -HOUR (1) },	/* Middle European */
+    { "mewt",	tZONE,     -HOUR (1) },	/* Middle European Winter */
+    { "mest",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "mesz",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "swt",	tZONE,     -HOUR (1) },	/* Swedish Winter */
+    { "sst",	tDAYZONE,  -HOUR (1) },	/* Swedish Summer */
+    { "fwt",	tZONE,     -HOUR (1) },	/* French Winter */
+    { "fst",	tDAYZONE,  -HOUR (1) },	/* French Summer */
+    { "eet",	tZONE,     -HOUR (2) },	/* Eastern Europe, USSR Zone 1 */
+    { "bt",	tZONE,     -HOUR (3) },	/* Baghdad, USSR Zone 2 */
+#if 0
+    { "it",	tZONE,     -HOUR (3.5) },/* Iran */
+#endif
+    { "zp4",	tZONE,     -HOUR (4) },	/* USSR Zone 3 */
+    { "zp5",	tZONE,     -HOUR (5) },	/* USSR Zone 4 */
+#if 0
+    { "ist",	tZONE,     -HOUR (5.5) },/* Indian Standard */
+#endif
+    { "zp6",	tZONE,     -HOUR (6) },	/* USSR Zone 5 */
+#if	0
+    /* For completeness.  NST is also Newfoundland Standard, and SST is
+     * also Swedish Summer. */
+    { "nst",	tZONE,     -HOUR (6.5) },/* North Sumatra */
+    { "sst",	tZONE,     -HOUR (7) },	/* South Sumatra, USSR Zone 6 */
+#endif	/* 0 */
+    { "wast",	tZONE,     -HOUR (7) },	/* West Australian Standard */
+    { "wadt",	tDAYZONE,  -HOUR (7) },	/* West Australian Daylight */
+#if 0
+    { "jt",	tZONE,     -HOUR (7.5) },/* Java (3pm in Cronusland!) */
+#endif
+    { "cct",	tZONE,     -HOUR (8) },	/* China Coast, USSR Zone 7 */
+    { "jst",	tZONE,     -HOUR (9) },	/* Japan Standard, USSR Zone 8 */
+#if 0
+    { "cast",	tZONE,     -HOUR (9.5) },/* Central Australian Standard */
+    { "cadt",	tDAYZONE,  -HOUR (9.5) },/* Central Australian Daylight */
+#endif
+    { "east",	tZONE,     -HOUR (10) },	/* Eastern Australian Standard */
+    { "eadt",	tDAYZONE,  -HOUR (10) },	/* Eastern Australian Daylight */
+    { "gst",	tZONE,     -HOUR (10) },	/* Guam Standard, USSR Zone 9 */
+    { "nzt",	tZONE,     -HOUR (12) },	/* New Zealand */
+    { "nzst",	tZONE,     -HOUR (12) },	/* New Zealand Standard */
+    { "nzdt",	tDAYZONE,  -HOUR (12) },	/* New Zealand Daylight */
+    { "idle",	tZONE,     -HOUR (12) },	/* International Date Line East */
+    {  NULL, 0, 0  }
+};
+
+/* Military timezone table. */
+static TABLE const MilitaryTable[] = {
+    { "a",	tZONE,	HOUR (  1) },
+    { "b",	tZONE,	HOUR (  2) },
+    { "c",	tZONE,	HOUR (  3) },
+    { "d",	tZONE,	HOUR (  4) },
+    { "e",	tZONE,	HOUR (  5) },
+    { "f",	tZONE,	HOUR (  6) },
+    { "g",	tZONE,	HOUR (  7) },
+    { "h",	tZONE,	HOUR (  8) },
+    { "i",	tZONE,	HOUR (  9) },
+    { "k",	tZONE,	HOUR ( 10) },
+    { "l",	tZONE,	HOUR ( 11) },
+    { "m",	tZONE,	HOUR ( 12) },
+    { "n",	tZONE,	HOUR (- 1) },
+    { "o",	tZONE,	HOUR (- 2) },
+    { "p",	tZONE,	HOUR (- 3) },
+    { "q",	tZONE,	HOUR (- 4) },
+    { "r",	tZONE,	HOUR (- 5) },
+    { "s",	tZONE,	HOUR (- 6) },
+    { "t",	tZONE,	HOUR (- 7) },
+    { "u",	tZONE,	HOUR (- 8) },
+    { "v",	tZONE,	HOUR (- 9) },
+    { "w",	tZONE,	HOUR (-10) },
+    { "x",	tZONE,	HOUR (-11) },
+    { "y",	tZONE,	HOUR (-12) },
+    { "z",	tZONE,	HOUR (  0) },
+    { NULL, 0, 0 }
+};
+
+
+
+
+/* ARGSUSED */
+static int
+yyerror (s)
+     char *s ATTRIBUTE_UNUSED;
+{
+  return 0;
+}
+
+static int
+ToHour (Hours, Meridian)
+     int Hours;
+     MERIDIAN Meridian;
+{
+  switch (Meridian)
+    {
+    case MER24:
+      if (Hours < 0 || Hours > 23)
+	return -1;
+      return Hours;
+    case MERam:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours;
+    case MERpm:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours + 12;
+    default:
+      abort ();
+    }
+  /* NOTREACHED */
+}
+
+static int
+ToYear (Year)
+     int Year;
+{
+  if (Year < 0)
+    Year = -Year;
+
+  /* XPG4 suggests that years 00-68 map to 2000-2068, and
+     years 69-99 map to 1969-1999.  */
+  if (Year < 69)
+    Year += 2000;
+  else if (Year < 100)
+    Year += 1900;
+
+  return Year;
+}
+
+static int
+LookupWord (buff)
+     char *buff;
+{
+  register char *p;
+  register char *q;
+  register const TABLE *tp;
+  int i;
+  int abbrev;
+
+  /* Make it lowercase. */
+  for (p = buff; *p; p++)
+    if (ISUPPER ((unsigned char) *p))
+      *p = tolower ((unsigned char) *p);
+
+  if (strcmp (buff, "am") == 0 || strcmp (buff, "a.m.") == 0)
+    {
+      yylval.Meridian = MERam;
+      return tMERIDIAN;
+    }
+  if (strcmp (buff, "pm") == 0 || strcmp (buff, "p.m.") == 0)
+    {
+      yylval.Meridian = MERpm;
+      return tMERIDIAN;
+    }
+
+  /* See if we have an abbreviation for a month. */
+  if (strlen (buff) == 3)
+    abbrev = 1;
+  else if (strlen (buff) == 4 && buff[3] == '.')
+    {
+      abbrev = 1;
+      buff[3] = '\0';
+    }
+  else
+    abbrev = 0;
+
+  for (tp = MonthDayTable; tp->name; tp++)
+    {
+      if (abbrev)
+	{
+	  if (strncmp (buff, tp->name, 3) == 0)
+	    {
+	      yylval.Number = tp->value;
+	      return tp->type;
+	    }
+	}
+      else if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+    }
+
+  for (tp = TimezoneTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  if (strcmp (buff, "dst") == 0)
+    return tDST;
+
+  for (tp = UnitsTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Strip off any plural and try the units table again. */
+  i = strlen (buff) - 1;
+  if (buff[i] == 's')
+    {
+      buff[i] = '\0';
+      for (tp = UnitsTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+      buff[i] = 's';		/* Put back for "this" in OtherTable. */
+    }
+
+  for (tp = OtherTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Military timezones. */
+  if (buff[1] == '\0' && ISALPHA ((unsigned char) *buff))
+    {
+      for (tp = MilitaryTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+    }
+
+  /* Drop out any periods and try the timezone table again. */
+  for (i = 0, p = q = buff; *q; q++)
+    if (*q != '.')
+      *p++ = *q;
+    else
+      i++;
+  *p = '\0';
+  if (i)
+    for (tp = TimezoneTable; tp->name; tp++)
+      if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+
+  return tID;
+}
+
+static int
+yylex ()
+{
+  register unsigned char c;
+  register char *p;
+  char buff[20];
+  int Count;
+  int sign;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *yyInput))
+	yyInput++;
+
+      if (ISDIGIT (c = *yyInput) || c == '-' || c == '+')
+	{
+	  if (c == '-' || c == '+')
+	    {
+	      sign = c == '-' ? -1 : 1;
+	      if (!ISDIGIT (*++yyInput))
+		/* skip the '-' sign */
+		continue;
+	    }
+	  else
+	    sign = 0;
+	  for (yylval.Number = 0; ISDIGIT (c = *yyInput++);)
+	    yylval.Number = 10 * yylval.Number + c - '0';
+	  yyInput--;
+	  if (sign < 0)
+	    yylval.Number = -yylval.Number;
+	  return sign ? tSNUMBER : tUNUMBER;
+	}
+      if (ISALPHA (c))
+	{
+	  for (p = buff; (c = *yyInput++, ISALPHA (c)) || c == '.';)
+	    if (p < &buff[sizeof buff - 1])
+	      *p++ = c;
+	  *p = '\0';
+	  yyInput--;
+	  return LookupWord (buff);
+	}
+      if (c != '(')
+	return *yyInput++;
+      Count = 0;
+      do
+	{
+	  c = *yyInput++;
+	  if (c == '\0')
+	    return c;
+	  if (c == '(')
+	    Count++;
+	  else if (c == ')')
+	    Count--;
+	}
+      while (Count > 0);
+    }
+}
+
+#define TM_YEAR_ORIGIN 1900
+
+/* Yield A - B, measured in seconds.  */
+static long
+difftm (struct tm *a, struct tm *b)
+{
+  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
+  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
+  long days = (
+  /* difference in day of year */
+		a->tm_yday - b->tm_yday
+  /* + intervening leap days */
+		+ ((ay >> 2) - (by >> 2))
+		- (ay / 100 - by / 100)
+		+ ((ay / 100 >> 2) - (by / 100 >> 2))
+  /* + difference in years * 365 */
+		+ (long) (ay - by) * 365
+  );
+  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+	  + (a->tm_sec - b->tm_sec));
+}
+
+time_t
+get_date (const char *p, const time_t *now)
+{
+  struct tm tm, tm0, *tmp;
+  time_t Start;
+
+  yyInput = p;
+  Start = now ? *now : time ((time_t *) NULL);
+  tmp = localtime (&Start);
+  if (!tmp)
+    return -1;
+  yyYear = tmp->tm_year + TM_YEAR_ORIGIN;
+  yyMonth = tmp->tm_mon + 1;
+  yyDay = tmp->tm_mday;
+  yyHour = tmp->tm_hour;
+  yyMinutes = tmp->tm_min;
+  yySeconds = tmp->tm_sec;
+  tm.tm_isdst = tmp->tm_isdst;
+  yyMeridian = MER24;
+  yyRelSeconds = 0;
+  yyRelMinutes = 0;
+  yyRelHour = 0;
+  yyRelDay = 0;
+  yyRelMonth = 0;
+  yyRelYear = 0;
+  yyHaveDate = 0;
+  yyHaveDay = 0;
+  yyHaveRel = 0;
+  yyHaveTime = 0;
+  yyHaveZone = 0;
+
+  if (yyparse ()
+      || yyHaveTime > 1 || yyHaveZone > 1 || yyHaveDate > 1 || yyHaveDay > 1)
+    return -1;
+
+  tm.tm_year = ToYear (yyYear) - TM_YEAR_ORIGIN + yyRelYear;
+  tm.tm_mon = yyMonth - 1 + yyRelMonth;
+  tm.tm_mday = yyDay + yyRelDay;
+  if (yyHaveTime || (yyHaveRel && !yyHaveDate && !yyHaveDay))
+    {
+      tm.tm_hour = ToHour (yyHour, yyMeridian);
+      if (tm.tm_hour < 0)
+	return -1;
+      tm.tm_min = yyMinutes;
+      tm.tm_sec = yySeconds;
+    }
+  else
+    {
+      tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+    }
+  tm.tm_hour += yyRelHour;
+  tm.tm_min += yyRelMinutes;
+  tm.tm_sec += yyRelSeconds;
+
+  /* Let mktime deduce tm_isdst if we have an absolute timestamp,
+     or if the relative timestamp mentions days, months, or years.  */
+  if (yyHaveDate | yyHaveDay | yyHaveTime | yyRelDay | yyRelMonth | yyRelYear)
+    tm.tm_isdst = -1;
+
+  tm0 = tm;
+
+  Start = mktime (&tm);
+
+  if (Start == (time_t) -1)
+    {
+
+      /* Guard against falsely reporting errors near the time_t boundaries
+         when parsing times in other time zones.  For example, if the min
+         time_t value is 1970-01-01 00:00:00 UTC and we are 8 hours ahead
+         of UTC, then the min localtime value is 1970-01-01 08:00:00; if
+         we apply mktime to 1970-01-01 00:00:00 we will get an error, so
+         we apply mktime to 1970-01-02 08:00:00 instead and adjust the time
+         zone by 24 hours to compensate.  This algorithm assumes that
+         there is no DST transition within a day of the time_t boundaries.  */
+      if (yyHaveZone)
+	{
+	  tm = tm0;
+	  if (tm.tm_year <= EPOCH - TM_YEAR_ORIGIN)
+	    {
+	      tm.tm_mday++;
+	      yyTimezone -= 24 * 60;
+	    }
+	  else
+	    {
+	      tm.tm_mday--;
+	      yyTimezone += 24 * 60;
+	    }
+	  Start = mktime (&tm);
+	}
+
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveDay && !yyHaveDate)
+    {
+      tm.tm_mday += ((yyDayNumber - tm.tm_wday + 7) % 7
+		     + 7 * (yyDayOrdinal - (0 < yyDayOrdinal)));
+      Start = mktime (&tm);
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveZone)
+    {
+      long delta;
+      struct tm *gmt = gmtime (&Start);
+      if (!gmt)
+	return -1;
+      delta = yyTimezone * 60L + difftm (&tm, gmt);
+      if ((Start + delta < Start) != (delta < 0))
+	return -1;		/* time_t overflow */
+      Start += delta;
+    }
+
+  return Start;
+}
+
+#if	defined (TEST)
+
+/* ARGSUSED */
+int
+main (ac, av)
+     int ac;
+     char *av[];
+{
+  char buff[MAX_BUFF_LEN + 1];
+  time_t d;
+
+  (void) printf ("Enter date, or blank line to exit.\n\t> ");
+  (void) fflush (stdout);
+
+  buff[MAX_BUFF_LEN] = 0;
+  while (fgets (buff, MAX_BUFF_LEN, stdin) && buff[0])
+    {
+      d = get_date (buff, (time_t *) NULL);
+      if (d == -1)
+	(void) printf ("Bad format - couldn't convert.\n");
+      else
+	(void) printf ("%s", ctime (&d));
+      (void) printf ("\t> ");
+      (void) fflush (stdout);
+    }
+  exit (0);
+  /* NOTREACHED */
+}
+#endif /* defined (TEST) */
diff --git a/getdate.h b/getdate.h
new file mode 100644
index 0000000..a190d2d
--- /dev/null
+++ b/getdate.h
@@ -0,0 +1,28 @@
+/*  Copyright (C) 1995 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. */
+
+/* Modified from the original to add stdlib.h and string.h */
+
+#ifndef GOT_GETDATE_H
+#define GOT_GETDATE_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+time_t get_date (const char *p, const time_t *now);
+
+#endif /* GOT_GETDATE_H */
diff --git a/getdate.y b/getdate.y
new file mode 100644
index 0000000..f87875c
--- /dev/null
+++ b/getdate.y
@@ -0,0 +1,1044 @@
+%{
+/*
+**  Originally written by Steven M. Bellovin <smb@research.att.com> while
+**  at the University of North Carolina at Chapel Hill.  Later tweaked by
+**  a couple of people on Usenet.  Completely overhauled by Rich $alz
+**  <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
+**
+**  This code is in the public domain and has no copyright.
+*/
+
+#include "config.h"
+
+/* Since the code of getdate.y is not included in the Emacs executable
+   itself, there is no need to #define static in this file.  Even if
+   the code were included in the Emacs executable, it probably
+   wouldn't do any harm to #undef it here; this will only cause
+   problems if we try to write to a static variable, which I don't
+   think this code needs to do.  */
+#ifdef emacs
+# undef static
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+
+#if HAVE_STDLIB_H
+# include <stdlib.h> /* for `free'; used by Bison 1.27 */
+#endif
+
+#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+#endif
+
+#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
+#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
+#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c))
+#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+
+/* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
+   only '0' through '9' are digits.  Prefer ISDIGIT to ISDIGIT_LOCALE unless
+   it's important to use the locale's definition of `digit' even when the
+   host does not conform to Posix.  */
+#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
+
+#if defined (STDC_HEADERS) || defined (USG)
+# include <string.h>
+#endif
+
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
+# define __attribute__(x)
+#endif
+
+#ifndef ATTRIBUTE_UNUSED
+# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#endif
+
+/* Some old versions of bison generate parsers that use bcopy.
+   That loses on systems that don't provide the function, so we have
+   to redefine it here.  */
+#if !defined (HAVE_BCOPY) && defined (HAVE_MEMCPY) && !defined (bcopy)
+# define bcopy(from, to, len) memcpy ((to), (from), (len))
+#endif
+
+/* Remap normal yacc parser interface names (yyparse, yylex, yyerror, etc),
+   as well as gratuitiously global symbol names, so we can have multiple
+   yacc generated parsers in the same program.  Note that these are only
+   the variables produced by yacc.  If other parser generators (bison,
+   byacc, etc) produce additional global names that conflict at link time,
+   then those parser generators need to be fixed instead of adding those
+   names to this list. */
+
+#define yymaxdepth gd_maxdepth
+#define yyparse gd_parse
+#define yylex   gd_lex
+#define yyerror gd_error
+#define yylval  gd_lval
+#define yychar  gd_char
+#define yydebug gd_debug
+#define yypact  gd_pact
+#define yyr1    gd_r1
+#define yyr2    gd_r2
+#define yydef   gd_def
+#define yychk   gd_chk
+#define yypgo   gd_pgo
+#define yyact   gd_act
+#define yyexca  gd_exca
+#define yyerrflag gd_errflag
+#define yynerrs gd_nerrs
+#define yyps    gd_ps
+#define yypv    gd_pv
+#define yys     gd_s
+#define yy_yys  gd_yys
+#define yystate gd_state
+#define yytmp   gd_tmp
+#define yyv     gd_v
+#define yy_yyv  gd_yyv
+#define yyval   gd_val
+#define yylloc  gd_lloc
+#define yyreds  gd_reds          /* With YYDEBUG defined */
+#define yytoks  gd_toks          /* With YYDEBUG defined */
+#define yylhs   gd_yylhs
+#define yylen   gd_yylen
+#define yydefred gd_yydefred
+#define yydgoto gd_yydgoto
+#define yysindex gd_yysindex
+#define yyrindex gd_yyrindex
+#define yygindex gd_yygindex
+#define yytable  gd_yytable
+#define yycheck  gd_yycheck
+
+static int yylex (void);
+static int yyerror (char *s);
+
+#define EPOCH		1970
+#define HOUR(x)		((x) * 60)
+
+#define MAX_BUFF_LEN    128   /* size of buffer to read the date into */
+
+/*
+**  An entry in the lexical lookup table.
+*/
+typedef struct _TABLE {
+    const char	*name;
+    int		type;
+    int		value;
+} TABLE;
+
+
+/*
+**  Meridian:  am, pm, or 24-hour style.
+*/
+typedef enum _MERIDIAN {
+    MERam, MERpm, MER24
+} MERIDIAN;
+
+
+/*
+**  Global variables.  We could get rid of most of these by using a good
+**  union as the yacc stack.  (This routine was originally written before
+**  yacc had the %union construct.)  Maybe someday; right now we only use
+**  the %union very rarely.
+*/
+static const char	*yyInput;
+static int	yyDayOrdinal;
+static int	yyDayNumber;
+static int	yyHaveDate;
+static int	yyHaveDay;
+static int	yyHaveRel;
+static int	yyHaveTime;
+static int	yyHaveZone;
+static int	yyTimezone;
+static int	yyDay;
+static int	yyHour;
+static int	yyMinutes;
+static int	yyMonth;
+static int	yySeconds;
+static int	yyYear;
+static MERIDIAN	yyMeridian;
+static int	yyRelDay;
+static int	yyRelHour;
+static int	yyRelMinutes;
+static int	yyRelMonth;
+static int	yyRelSeconds;
+static int	yyRelYear;
+
+%}
+
+/* This grammar has 13 shift/reduce conflicts. */
+%expect 13
+
+%union {
+    int			Number;
+    enum _MERIDIAN	Meridian;
+}
+
+%token	tAGO tDAY tDAY_UNIT tDAYZONE tDST tHOUR_UNIT tID
+%token	tMERIDIAN tMINUTE_UNIT tMONTH tMONTH_UNIT
+%token	tSEC_UNIT tSNUMBER tUNUMBER tYEAR_UNIT tZONE
+
+%type	<Number>	tDAY tDAY_UNIT tDAYZONE tHOUR_UNIT tMINUTE_UNIT
+%type	<Number>	tMONTH tMONTH_UNIT
+%type	<Number>	tSEC_UNIT tSNUMBER tUNUMBER tYEAR_UNIT tZONE
+%type	<Meridian>	tMERIDIAN o_merid
+
+%%
+
+spec	: /* NULL */
+	| spec item
+	;
+
+item	: time {
+	    yyHaveTime++;
+	}
+	| zone {
+	    yyHaveZone++;
+	}
+	| date {
+	    yyHaveDate++;
+	}
+	| day {
+	    yyHaveDay++;
+	}
+	| rel {
+	    yyHaveRel++;
+	}
+	| number
+	;
+
+time	: tUNUMBER tMERIDIAN {
+	    yyHour = $1;
+	    yyMinutes = 0;
+	    yySeconds = 0;
+	    yyMeridian = $2;
+	}
+	| tUNUMBER ':' tUNUMBER o_merid {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = 0;
+	    yyMeridian = $4;
+	}
+	| tUNUMBER ':' tUNUMBER tSNUMBER {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ($4 < 0
+			  ? -$4 % 100 + (-$4 / 100) * 60
+			  : - ($4 % 100 + ($4 / 100) * 60));
+	}
+	| tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = $5;
+	    yyMeridian = $6;
+	}
+	| tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = $5;
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ($6 < 0
+			  ? -$6 % 100 + (-$6 / 100) * 60
+			  : - ($6 % 100 + ($6 / 100) * 60));
+	}
+	;
+
+zone	: tZONE {
+	    yyTimezone = $1;
+	}
+	| tDAYZONE {
+	    yyTimezone = $1 - 60;
+	}
+	|
+	  tZONE tDST {
+	    yyTimezone = $1 - 60;
+	}
+	;
+
+day	: tDAY {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = $1;
+	}
+	| tDAY ',' {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = $1;
+	}
+	| tUNUMBER tDAY {
+	    yyDayOrdinal = $1;
+	    yyDayNumber = $2;
+	}
+	;
+
+date	: tUNUMBER '/' tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $3;
+	}
+	| tUNUMBER '/' tUNUMBER '/' tUNUMBER {
+	  /* Interpret as YYYY/MM/DD if $1 >= 1000, otherwise as MM/DD/YY.
+	     The goal in recognizing YYYY/MM/DD is solely to support legacy
+	     machine-generated dates like those in an RCS log listing.  If
+	     you want portability, use the ISO 8601 format.  */
+	  if ($1 >= 1000)
+	    {
+	      yyYear = $1;
+	      yyMonth = $3;
+	      yyDay = $5;
+	    }
+	  else
+	    {
+	      yyMonth = $1;
+	      yyDay = $3;
+	      yyYear = $5;
+	    }
+	}
+	| tUNUMBER tSNUMBER tSNUMBER {
+	    /* ISO 8601 format.  yyyy-mm-dd.  */
+	    yyYear = $1;
+	    yyMonth = -$2;
+	    yyDay = -$3;
+	}
+	| tUNUMBER tMONTH tSNUMBER {
+	    /* e.g. 17-JUN-1992.  */
+	    yyDay = $1;
+	    yyMonth = $2;
+	    yyYear = -$3;
+	}
+	| tMONTH tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $2;
+	}
+	| tMONTH tUNUMBER ',' tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $2;
+	    yyYear = $4;
+	}
+	| tUNUMBER tMONTH {
+	    yyMonth = $2;
+	    yyDay = $1;
+	}
+	| tUNUMBER tMONTH tUNUMBER {
+	    yyMonth = $2;
+	    yyDay = $1;
+	    yyYear = $3;
+	}
+	;
+
+rel	: relunit tAGO {
+	    yyRelSeconds = -yyRelSeconds;
+	    yyRelMinutes = -yyRelMinutes;
+	    yyRelHour = -yyRelHour;
+	    yyRelDay = -yyRelDay;
+	    yyRelMonth = -yyRelMonth;
+	    yyRelYear = -yyRelYear;
+	}
+	| relunit
+	;
+
+relunit	: tUNUMBER tYEAR_UNIT {
+	    yyRelYear += $1 * $2;
+	}
+	| tSNUMBER tYEAR_UNIT {
+	    yyRelYear += $1 * $2;
+	}
+	| tYEAR_UNIT {
+	    yyRelYear += $1;
+	}
+	| tUNUMBER tMONTH_UNIT {
+	    yyRelMonth += $1 * $2;
+	}
+	| tSNUMBER tMONTH_UNIT {
+	    yyRelMonth += $1 * $2;
+	}
+	| tMONTH_UNIT {
+	    yyRelMonth += $1;
+	}
+	| tUNUMBER tDAY_UNIT {
+	    yyRelDay += $1 * $2;
+	}
+	| tSNUMBER tDAY_UNIT {
+	    yyRelDay += $1 * $2;
+	}
+	| tDAY_UNIT {
+	    yyRelDay += $1;
+	}
+	| tUNUMBER tHOUR_UNIT {
+	    yyRelHour += $1 * $2;
+	}
+	| tSNUMBER tHOUR_UNIT {
+	    yyRelHour += $1 * $2;
+	}
+	| tHOUR_UNIT {
+	    yyRelHour += $1;
+	}
+	| tUNUMBER tMINUTE_UNIT {
+	    yyRelMinutes += $1 * $2;
+	}
+	| tSNUMBER tMINUTE_UNIT {
+	    yyRelMinutes += $1 * $2;
+	}
+	| tMINUTE_UNIT {
+	    yyRelMinutes += $1;
+	}
+	| tUNUMBER tSEC_UNIT {
+	    yyRelSeconds += $1 * $2;
+	}
+	| tSNUMBER tSEC_UNIT {
+	    yyRelSeconds += $1 * $2;
+	}
+	| tSEC_UNIT {
+	    yyRelSeconds += $1;
+	}
+	;
+
+number	: tUNUMBER
+          {
+	    if (yyHaveTime && yyHaveDate && !yyHaveRel)
+	      yyYear = $1;
+	    else
+	      {
+		if ($1>10000)
+		  {
+		    yyHaveDate++;
+		    yyDay= ($1)%100;
+		    yyMonth= ($1/100)%100;
+		    yyYear = $1/10000;
+		  }
+		else
+		  {
+		    yyHaveTime++;
+		    if ($1 < 100)
+		      {
+			yyHour = $1;
+			yyMinutes = 0;
+		      }
+		    else
+		      {
+		    	yyHour = $1 / 100;
+		    	yyMinutes = $1 % 100;
+		      }
+		    yySeconds = 0;
+		    yyMeridian = MER24;
+		  }
+	      }
+	  }
+	;
+
+o_merid	: /* NULL */
+	  {
+	    $$ = MER24;
+	  }
+	| tMERIDIAN
+	  {
+	    $$ = $1;
+	  }
+	;
+
+%%
+
+/* Include this file down here because bison inserts code above which
+   may define-away `const'.  We want the prototype for get_date to have
+   the same signature as the function definition does. */
+#include "getdate.h"
+
+extern struct tm	*gmtime ();
+extern struct tm	*localtime ();
+extern time_t		mktime ();
+
+/* Month and day table. */
+static TABLE const MonthDayTable[] = {
+    { "january",	tMONTH,  1 },
+    { "february",	tMONTH,  2 },
+    { "march",		tMONTH,  3 },
+    { "april",		tMONTH,  4 },
+    { "may",		tMONTH,  5 },
+    { "june",		tMONTH,  6 },
+    { "july",		tMONTH,  7 },
+    { "august",		tMONTH,  8 },
+    { "september",	tMONTH,  9 },
+    { "sept",		tMONTH,  9 },
+    { "october",	tMONTH, 10 },
+    { "november",	tMONTH, 11 },
+    { "december",	tMONTH, 12 },
+    { "sunday",		tDAY, 0 },
+    { "monday",		tDAY, 1 },
+    { "tuesday",	tDAY, 2 },
+    { "tues",		tDAY, 2 },
+    { "wednesday",	tDAY, 3 },
+    { "wednes",		tDAY, 3 },
+    { "thursday",	tDAY, 4 },
+    { "thur",		tDAY, 4 },
+    { "thurs",		tDAY, 4 },
+    { "friday",		tDAY, 5 },
+    { "saturday",	tDAY, 6 },
+    { NULL, 0, 0 }
+};
+
+/* Time units table. */
+static TABLE const UnitsTable[] = {
+    { "year",		tYEAR_UNIT,	1 },
+    { "month",		tMONTH_UNIT,	1 },
+    { "fortnight",	tDAY_UNIT,	14 },
+    { "week",		tDAY_UNIT,	7 },
+    { "day",		tDAY_UNIT,	1 },
+    { "hour",		tHOUR_UNIT,	1 },
+    { "minute",		tMINUTE_UNIT,	1 },
+    { "min",		tMINUTE_UNIT,	1 },
+    { "second",		tSEC_UNIT,	1 },
+    { "sec",		tSEC_UNIT,	1 },
+    { NULL, 0, 0 }
+};
+
+/* Assorted relative-time words. */
+static TABLE const OtherTable[] = {
+    { "tomorrow",	tMINUTE_UNIT,	1 * 24 * 60 },
+    { "yesterday",	tMINUTE_UNIT,	-1 * 24 * 60 },
+    { "today",		tMINUTE_UNIT,	0 },
+    { "now",		tMINUTE_UNIT,	0 },
+    { "last",		tUNUMBER,	-1 },
+    { "this",		tMINUTE_UNIT,	0 },
+    { "next",		tUNUMBER,	1 },
+    { "first",		tUNUMBER,	1 },
+/*  { "second",		tUNUMBER,	2 }, */
+    { "third",		tUNUMBER,	3 },
+    { "fourth",		tUNUMBER,	4 },
+    { "fifth",		tUNUMBER,	5 },
+    { "sixth",		tUNUMBER,	6 },
+    { "seventh",	tUNUMBER,	7 },
+    { "eighth",		tUNUMBER,	8 },
+    { "ninth",		tUNUMBER,	9 },
+    { "tenth",		tUNUMBER,	10 },
+    { "eleventh",	tUNUMBER,	11 },
+    { "twelfth",	tUNUMBER,	12 },
+    { "ago",		tAGO,	1 },
+    { NULL, 0, 0 }
+};
+
+/* The timezone table. */
+static TABLE const TimezoneTable[] = {
+    { "gmt",	tZONE,     HOUR ( 0) },	/* Greenwich Mean */
+    { "ut",	tZONE,     HOUR ( 0) },	/* Universal (Coordinated) */
+    { "utc",	tZONE,     HOUR ( 0) },
+    { "wet",	tZONE,     HOUR ( 0) },	/* Western European */
+    { "bst",	tDAYZONE,  HOUR ( 0) },	/* British Summer */
+    { "wat",	tZONE,     HOUR ( 1) },	/* West Africa */
+    { "at",	tZONE,     HOUR ( 2) },	/* Azores */
+#if	0
+    /* For completeness.  BST is also British Summer, and GST is
+     * also Guam Standard. */
+    { "bst",	tZONE,     HOUR ( 3) },	/* Brazil Standard */
+    { "gst",	tZONE,     HOUR ( 3) },	/* Greenland Standard */
+#endif
+#if 0
+    { "nft",	tZONE,     HOUR (3.5) },	/* Newfoundland */
+    { "nst",	tZONE,     HOUR (3.5) },	/* Newfoundland Standard */
+    { "ndt",	tDAYZONE,  HOUR (3.5) },	/* Newfoundland Daylight */
+#endif
+    { "ast",	tZONE,     HOUR ( 4) },	/* Atlantic Standard */
+    { "adt",	tDAYZONE,  HOUR ( 4) },	/* Atlantic Daylight */
+    { "est",	tZONE,     HOUR ( 5) },	/* Eastern Standard */
+    { "edt",	tDAYZONE,  HOUR ( 5) },	/* Eastern Daylight */
+    { "cst",	tZONE,     HOUR ( 6) },	/* Central Standard */
+    { "cdt",	tDAYZONE,  HOUR ( 6) },	/* Central Daylight */
+    { "mst",	tZONE,     HOUR ( 7) },	/* Mountain Standard */
+    { "mdt",	tDAYZONE,  HOUR ( 7) },	/* Mountain Daylight */
+    { "pst",	tZONE,     HOUR ( 8) },	/* Pacific Standard */
+    { "pdt",	tDAYZONE,  HOUR ( 8) },	/* Pacific Daylight */
+    { "yst",	tZONE,     HOUR ( 9) },	/* Yukon Standard */
+    { "ydt",	tDAYZONE,  HOUR ( 9) },	/* Yukon Daylight */
+    { "hst",	tZONE,     HOUR (10) },	/* Hawaii Standard */
+    { "hdt",	tDAYZONE,  HOUR (10) },	/* Hawaii Daylight */
+    { "cat",	tZONE,     HOUR (10) },	/* Central Alaska */
+    { "ahst",	tZONE,     HOUR (10) },	/* Alaska-Hawaii Standard */
+    { "nt",	tZONE,     HOUR (11) },	/* Nome */
+    { "idlw",	tZONE,     HOUR (12) },	/* International Date Line West */
+    { "cet",	tZONE,     -HOUR (1) },	/* Central European */
+    { "met",	tZONE,     -HOUR (1) },	/* Middle European */
+    { "mewt",	tZONE,     -HOUR (1) },	/* Middle European Winter */
+    { "mest",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "mesz",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "swt",	tZONE,     -HOUR (1) },	/* Swedish Winter */
+    { "sst",	tDAYZONE,  -HOUR (1) },	/* Swedish Summer */
+    { "fwt",	tZONE,     -HOUR (1) },	/* French Winter */
+    { "fst",	tDAYZONE,  -HOUR (1) },	/* French Summer */
+    { "eet",	tZONE,     -HOUR (2) },	/* Eastern Europe, USSR Zone 1 */
+    { "bt",	tZONE,     -HOUR (3) },	/* Baghdad, USSR Zone 2 */
+#if 0
+    { "it",	tZONE,     -HOUR (3.5) },/* Iran */
+#endif
+    { "zp4",	tZONE,     -HOUR (4) },	/* USSR Zone 3 */
+    { "zp5",	tZONE,     -HOUR (5) },	/* USSR Zone 4 */
+#if 0
+    { "ist",	tZONE,     -HOUR (5.5) },/* Indian Standard */
+#endif
+    { "zp6",	tZONE,     -HOUR (6) },	/* USSR Zone 5 */
+#if	0
+    /* For completeness.  NST is also Newfoundland Standard, and SST is
+     * also Swedish Summer. */
+    { "nst",	tZONE,     -HOUR (6.5) },/* North Sumatra */
+    { "sst",	tZONE,     -HOUR (7) },	/* South Sumatra, USSR Zone 6 */
+#endif	/* 0 */
+    { "wast",	tZONE,     -HOUR (7) },	/* West Australian Standard */
+    { "wadt",	tDAYZONE,  -HOUR (7) },	/* West Australian Daylight */
+#if 0
+    { "jt",	tZONE,     -HOUR (7.5) },/* Java (3pm in Cronusland!) */
+#endif
+    { "cct",	tZONE,     -HOUR (8) },	/* China Coast, USSR Zone 7 */
+    { "jst",	tZONE,     -HOUR (9) },	/* Japan Standard, USSR Zone 8 */
+#if 0
+    { "cast",	tZONE,     -HOUR (9.5) },/* Central Australian Standard */
+    { "cadt",	tDAYZONE,  -HOUR (9.5) },/* Central Australian Daylight */
+#endif
+    { "east",	tZONE,     -HOUR (10) },	/* Eastern Australian Standard */
+    { "eadt",	tDAYZONE,  -HOUR (10) },	/* Eastern Australian Daylight */
+    { "gst",	tZONE,     -HOUR (10) },	/* Guam Standard, USSR Zone 9 */
+    { "nzt",	tZONE,     -HOUR (12) },	/* New Zealand */
+    { "nzst",	tZONE,     -HOUR (12) },	/* New Zealand Standard */
+    { "nzdt",	tDAYZONE,  -HOUR (12) },	/* New Zealand Daylight */
+    { "idle",	tZONE,     -HOUR (12) },	/* International Date Line East */
+    {  NULL, 0, 0  }
+};
+
+/* Military timezone table. */
+static TABLE const MilitaryTable[] = {
+    { "a",	tZONE,	HOUR (  1) },
+    { "b",	tZONE,	HOUR (  2) },
+    { "c",	tZONE,	HOUR (  3) },
+    { "d",	tZONE,	HOUR (  4) },
+    { "e",	tZONE,	HOUR (  5) },
+    { "f",	tZONE,	HOUR (  6) },
+    { "g",	tZONE,	HOUR (  7) },
+    { "h",	tZONE,	HOUR (  8) },
+    { "i",	tZONE,	HOUR (  9) },
+    { "k",	tZONE,	HOUR ( 10) },
+    { "l",	tZONE,	HOUR ( 11) },
+    { "m",	tZONE,	HOUR ( 12) },
+    { "n",	tZONE,	HOUR (- 1) },
+    { "o",	tZONE,	HOUR (- 2) },
+    { "p",	tZONE,	HOUR (- 3) },
+    { "q",	tZONE,	HOUR (- 4) },
+    { "r",	tZONE,	HOUR (- 5) },
+    { "s",	tZONE,	HOUR (- 6) },
+    { "t",	tZONE,	HOUR (- 7) },
+    { "u",	tZONE,	HOUR (- 8) },
+    { "v",	tZONE,	HOUR (- 9) },
+    { "w",	tZONE,	HOUR (-10) },
+    { "x",	tZONE,	HOUR (-11) },
+    { "y",	tZONE,	HOUR (-12) },
+    { "z",	tZONE,	HOUR (  0) },
+    { NULL, 0, 0 }
+};
+
+
+
+
+/* ARGSUSED */
+static int
+yyerror (s)
+     char *s ATTRIBUTE_UNUSED;
+{
+  return 0;
+}
+
+static int
+ToHour (Hours, Meridian)
+     int Hours;
+     MERIDIAN Meridian;
+{
+  switch (Meridian)
+    {
+    case MER24:
+      if (Hours < 0 || Hours > 23)
+	return -1;
+      return Hours;
+    case MERam:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours;
+    case MERpm:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours + 12;
+    default:
+      abort ();
+    }
+  /* NOTREACHED */
+}
+
+static int
+ToYear (Year)
+     int Year;
+{
+  if (Year < 0)
+    Year = -Year;
+
+  /* XPG4 suggests that years 00-68 map to 2000-2068, and
+     years 69-99 map to 1969-1999.  */
+  if (Year < 69)
+    Year += 2000;
+  else if (Year < 100)
+    Year += 1900;
+
+  return Year;
+}
+
+static int
+LookupWord (buff)
+     char *buff;
+{
+  register char *p;
+  register char *q;
+  register const TABLE *tp;
+  int i;
+  int abbrev;
+
+  /* Make it lowercase. */
+  for (p = buff; *p; p++)
+    if (ISUPPER ((unsigned char) *p))
+      *p = tolower ((unsigned char) *p);
+
+  if (strcmp (buff, "am") == 0 || strcmp (buff, "a.m.") == 0)
+    {
+      yylval.Meridian = MERam;
+      return tMERIDIAN;
+    }
+  if (strcmp (buff, "pm") == 0 || strcmp (buff, "p.m.") == 0)
+    {
+      yylval.Meridian = MERpm;
+      return tMERIDIAN;
+    }
+
+  /* See if we have an abbreviation for a month. */
+  if (strlen (buff) == 3)
+    abbrev = 1;
+  else if (strlen (buff) == 4 && buff[3] == '.')
+    {
+      abbrev = 1;
+      buff[3] = '\0';
+    }
+  else
+    abbrev = 0;
+
+  for (tp = MonthDayTable; tp->name; tp++)
+    {
+      if (abbrev)
+	{
+	  if (strncmp (buff, tp->name, 3) == 0)
+	    {
+	      yylval.Number = tp->value;
+	      return tp->type;
+	    }
+	}
+      else if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+    }
+
+  for (tp = TimezoneTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  if (strcmp (buff, "dst") == 0)
+    return tDST;
+
+  for (tp = UnitsTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Strip off any plural and try the units table again. */
+  i = strlen (buff) - 1;
+  if (buff[i] == 's')
+    {
+      buff[i] = '\0';
+      for (tp = UnitsTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+      buff[i] = 's';		/* Put back for "this" in OtherTable. */
+    }
+
+  for (tp = OtherTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Military timezones. */
+  if (buff[1] == '\0' && ISALPHA ((unsigned char) *buff))
+    {
+      for (tp = MilitaryTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+    }
+
+  /* Drop out any periods and try the timezone table again. */
+  for (i = 0, p = q = buff; *q; q++)
+    if (*q != '.')
+      *p++ = *q;
+    else
+      i++;
+  *p = '\0';
+  if (i)
+    for (tp = TimezoneTable; tp->name; tp++)
+      if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+
+  return tID;
+}
+
+static int
+yylex ()
+{
+  register unsigned char c;
+  register char *p;
+  char buff[20];
+  int Count;
+  int sign;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *yyInput))
+	yyInput++;
+
+      if (ISDIGIT (c = *yyInput) || c == '-' || c == '+')
+	{
+	  if (c == '-' || c == '+')
+	    {
+	      sign = c == '-' ? -1 : 1;
+	      if (!ISDIGIT (*++yyInput))
+		/* skip the '-' sign */
+		continue;
+	    }
+	  else
+	    sign = 0;
+	  for (yylval.Number = 0; ISDIGIT (c = *yyInput++);)
+	    yylval.Number = 10 * yylval.Number + c - '0';
+	  yyInput--;
+	  if (sign < 0)
+	    yylval.Number = -yylval.Number;
+	  return sign ? tSNUMBER : tUNUMBER;
+	}
+      if (ISALPHA (c))
+	{
+	  for (p = buff; (c = *yyInput++, ISALPHA (c)) || c == '.';)
+	    if (p < &buff[sizeof buff - 1])
+	      *p++ = c;
+	  *p = '\0';
+	  yyInput--;
+	  return LookupWord (buff);
+	}
+      if (c != '(')
+	return *yyInput++;
+      Count = 0;
+      do
+	{
+	  c = *yyInput++;
+	  if (c == '\0')
+	    return c;
+	  if (c == '(')
+	    Count++;
+	  else if (c == ')')
+	    Count--;
+	}
+      while (Count > 0);
+    }
+}
+
+#define TM_YEAR_ORIGIN 1900
+
+/* Yield A - B, measured in seconds.  */
+static long
+difftm (struct tm *a, struct tm *b)
+{
+  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
+  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
+  long days = (
+  /* difference in day of year */
+		a->tm_yday - b->tm_yday
+  /* + intervening leap days */
+		+ ((ay >> 2) - (by >> 2))
+		- (ay / 100 - by / 100)
+		+ ((ay / 100 >> 2) - (by / 100 >> 2))
+  /* + difference in years * 365 */
+		+ (long) (ay - by) * 365
+  );
+  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+	  + (a->tm_sec - b->tm_sec));
+}
+
+time_t
+get_date (const char *p, const time_t *now)
+{
+  struct tm tm, tm0, *tmp;
+  time_t Start;
+
+  yyInput = p;
+  Start = now ? *now : time ((time_t *) NULL);
+  tmp = localtime (&Start);
+  if (!tmp)
+    return -1;
+  yyYear = tmp->tm_year + TM_YEAR_ORIGIN;
+  yyMonth = tmp->tm_mon + 1;
+  yyDay = tmp->tm_mday;
+  yyHour = tmp->tm_hour;
+  yyMinutes = tmp->tm_min;
+  yySeconds = tmp->tm_sec;
+  tm.tm_isdst = tmp->tm_isdst;
+  yyMeridian = MER24;
+  yyRelSeconds = 0;
+  yyRelMinutes = 0;
+  yyRelHour = 0;
+  yyRelDay = 0;
+  yyRelMonth = 0;
+  yyRelYear = 0;
+  yyHaveDate = 0;
+  yyHaveDay = 0;
+  yyHaveRel = 0;
+  yyHaveTime = 0;
+  yyHaveZone = 0;
+
+  if (yyparse ()
+      || yyHaveTime > 1 || yyHaveZone > 1 || yyHaveDate > 1 || yyHaveDay > 1)
+    return -1;
+
+  tm.tm_year = ToYear (yyYear) - TM_YEAR_ORIGIN + yyRelYear;
+  tm.tm_mon = yyMonth - 1 + yyRelMonth;
+  tm.tm_mday = yyDay + yyRelDay;
+  if (yyHaveTime || (yyHaveRel && !yyHaveDate && !yyHaveDay))
+    {
+      tm.tm_hour = ToHour (yyHour, yyMeridian);
+      if (tm.tm_hour < 0)
+	return -1;
+      tm.tm_min = yyMinutes;
+      tm.tm_sec = yySeconds;
+    }
+  else
+    {
+      tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+    }
+  tm.tm_hour += yyRelHour;
+  tm.tm_min += yyRelMinutes;
+  tm.tm_sec += yyRelSeconds;
+
+  /* Let mktime deduce tm_isdst if we have an absolute timestamp,
+     or if the relative timestamp mentions days, months, or years.  */
+  if (yyHaveDate | yyHaveDay | yyHaveTime | yyRelDay | yyRelMonth | yyRelYear)
+    tm.tm_isdst = -1;
+
+  tm0 = tm;
+
+  Start = mktime (&tm);
+
+  if (Start == (time_t) -1)
+    {
+
+      /* Guard against falsely reporting errors near the time_t boundaries
+         when parsing times in other time zones.  For example, if the min
+         time_t value is 1970-01-01 00:00:00 UTC and we are 8 hours ahead
+         of UTC, then the min localtime value is 1970-01-01 08:00:00; if
+         we apply mktime to 1970-01-01 00:00:00 we will get an error, so
+         we apply mktime to 1970-01-02 08:00:00 instead and adjust the time
+         zone by 24 hours to compensate.  This algorithm assumes that
+         there is no DST transition within a day of the time_t boundaries.  */
+      if (yyHaveZone)
+	{
+	  tm = tm0;
+	  if (tm.tm_year <= EPOCH - TM_YEAR_ORIGIN)
+	    {
+	      tm.tm_mday++;
+	      yyTimezone -= 24 * 60;
+	    }
+	  else
+	    {
+	      tm.tm_mday--;
+	      yyTimezone += 24 * 60;
+	    }
+	  Start = mktime (&tm);
+	}
+
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveDay && !yyHaveDate)
+    {
+      tm.tm_mday += ((yyDayNumber - tm.tm_wday + 7) % 7
+		     + 7 * (yyDayOrdinal - (0 < yyDayOrdinal)));
+      Start = mktime (&tm);
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveZone)
+    {
+      long delta;
+      struct tm *gmt = gmtime (&Start);
+      if (!gmt)
+	return -1;
+      delta = yyTimezone * 60L + difftm (&tm, gmt);
+      if ((Start + delta < Start) != (delta < 0))
+	return -1;		/* time_t overflow */
+      Start += delta;
+    }
+
+  return Start;
+}
+
+#if	defined (TEST)
+
+/* ARGSUSED */
+int
+main (ac, av)
+     int ac;
+     char *av[];
+{
+  char buff[MAX_BUFF_LEN + 1];
+  time_t d;
+
+  (void) printf ("Enter date, or blank line to exit.\n\t> ");
+  (void) fflush (stdout);
+
+  buff[MAX_BUFF_LEN] = 0;
+  while (fgets (buff, MAX_BUFF_LEN, stdin) && buff[0])
+    {
+      d = get_date (buff, (time_t *) NULL);
+      if (d == -1)
+	(void) printf ("Bad format - couldn't convert.\n");
+      else
+	(void) printf ("%s", ctime (&d));
+      (void) printf ("\t> ");
+      (void) fflush (stdout);
+    }
+  exit (0);
+  /* NOTREACHED */
+}
+#endif /* defined (TEST) */
diff --git a/hash.h b/hash.h
new file mode 100644
index 0000000..39abf27
--- /dev/null
+++ b/hash.h
@@ -0,0 +1,57 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for crypto hashing.
+
+  */
+
+#ifndef GOT_HASH_H
+#define GOT_HASH_H
+
+/* length of hash values produced by SHA512 */
+#define MAX_HASH_LENGTH 64
+
+typedef enum {
+  HSH_INVALID = 0,
+  HSH_MD5 = 1,
+  HSH_SHA1 = 2,
+  HSH_SHA256 = 3,
+  HSH_SHA384 = 4,
+  HSH_SHA512 = 5,
+  HSH_SHA3_224 = 6,
+  HSH_SHA3_256 = 7,
+  HSH_SHA3_384 = 8,
+  HSH_SHA3_512 = 9,
+  HSH_TIGER = 10,
+  HSH_WHIRLPOOL = 11,
+  HSH_MD5_NONCRYPTO = 10000, /* For NTPv4 reference ID */
+} HSH_Algorithm;
+
+extern int HSH_GetHashId(HSH_Algorithm algorithm);
+
+extern int HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+                    unsigned char *out, int out_len);
+
+extern void HSH_Finalise(void);
+
+#endif
diff --git a/hash_gnutls.c b/hash_gnutls.c
new file mode 100644
index 0000000..269fdd8
--- /dev/null
+++ b/hash_gnutls.c
@@ -0,0 +1,145 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Crypto hashing using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "hash.h"
+#include "logging.h"
+
+struct hash {
+  const HSH_Algorithm algorithm;
+  const gnutls_digest_algorithm_t type;
+  gnutls_hash_hd_t handle;
+};
+
+static struct hash hashes[] = {
+  { HSH_MD5_NONCRYPTO, GNUTLS_DIG_MD5, NULL },
+  { HSH_MD5, GNUTLS_DIG_MD5, NULL },
+  { HSH_SHA1, GNUTLS_DIG_SHA1, NULL },
+  { HSH_SHA256, GNUTLS_DIG_SHA256, NULL },
+  { HSH_SHA384, GNUTLS_DIG_SHA384, NULL },
+  { HSH_SHA512, GNUTLS_DIG_SHA512, NULL },
+  { HSH_SHA3_224, GNUTLS_DIG_SHA3_224, NULL },
+  { HSH_SHA3_256, GNUTLS_DIG_SHA3_256, NULL },
+  { HSH_SHA3_384, GNUTLS_DIG_SHA3_384, NULL },
+  { HSH_SHA3_512, GNUTLS_DIG_SHA3_512, NULL },
+  { 0, 0, NULL }
+};
+
+static int gnutls_initialised = 0;
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int id, r;
+
+  if (!gnutls_initialised) {
+    r = gnutls_global_init();
+    if (r < 0)
+      LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+    gnutls_initialised = 1;
+  }
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[id].algorithm == 0)
+    return -1;
+
+  if (hashes[id].handle)
+    return id;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_LAX_MODE();
+
+  r = gnutls_hash_init(&hashes[id].handle, hashes[id].type);
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_STRICT_MODE();
+
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "hash", gnutls_strerror(r));
+    hashes[id].handle = NULL;
+    return -1;
+  }
+
+  return id;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  gnutls_hash_hd_t handle;
+  int hash_len;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  handle = hashes[id].handle;
+  hash_len = gnutls_hash_get_len(hashes[id].type);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hash(handle, in1, in1_len) < 0 ||
+      (in2 && gnutls_hash(handle, in2, in2_len) < 0)) {
+    /* Reset the state */
+    gnutls_hash_output(handle, buf);
+    return 0;
+  }
+
+  gnutls_hash_output(handle, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  if (!gnutls_initialised)
+    return;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].handle)
+      gnutls_hash_deinit(hashes[i].handle, NULL);
+  }
+
+  gnutls_global_deinit();
+}
diff --git a/hash_intmd5.c b/hash_intmd5.c
new file mode 100644
index 0000000..a64b735
--- /dev/null
+++ b/hash_intmd5.c
@@ -0,0 +1,71 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using internal MD5 implementation.
+
+  */
+
+#include "config.h"
+#include "sysincl.h"
+#include "hash.h"
+#include "memory.h"
+#include "util.h"
+
+#include "md5.c"
+
+static MD5_CTX ctx;
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  /* only MD5 is supported */
+  if (algorithm != HSH_MD5 && algorithm != HSH_MD5_NONCRYPTO)
+    return -1;
+
+  return 0;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  MD5Init(&ctx);
+  MD5Update(&ctx, in1, in1_len);
+  if (in2)
+    MD5Update(&ctx, in2, in2_len);
+  MD5Final(&ctx);
+
+  out_len = MIN(out_len, 16);
+
+  memcpy(out, ctx.digest, out_len);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+}
diff --git a/hash_nettle.c b/hash_nettle.c
new file mode 100644
index 0000000..4a214f6
--- /dev/null
+++ b/hash_nettle.c
@@ -0,0 +1,124 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using the nettle library.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <nettle/nettle-meta.h>
+
+#include "hash.h"
+#include "memory.h"
+
+struct hash {
+  const HSH_Algorithm algorithm;
+  const char *int_name;
+  const struct nettle_hash *nettle_hash;
+  void *context;
+};
+
+static struct hash hashes[] = {
+  { HSH_MD5, "md5", NULL, NULL },
+  { HSH_SHA1, "sha1", NULL, NULL },
+  { HSH_SHA256, "sha256", NULL, NULL },
+  { HSH_SHA384, "sha384", NULL, NULL },
+  { HSH_SHA512, "sha512", NULL, NULL },
+  { HSH_SHA3_224, "sha3_224", NULL, NULL },
+  { HSH_SHA3_256, "sha3_256", NULL, NULL },
+  { HSH_SHA3_384, "sha3_384", NULL, NULL },
+  { HSH_SHA3_512, "sha3_512", NULL, NULL },
+  { 0, NULL, NULL, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int id, nid;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[id].algorithm == 0)
+    return -1;
+
+  if (hashes[id].context)
+    return id;
+
+  for (nid = 0; nettle_hashes[nid]; nid++) {
+    if (!strcmp(hashes[id].int_name, nettle_hashes[nid]->name))
+      break;
+  }
+
+  if (!nettle_hashes[nid] || !nettle_hashes[nid]->context_size || !nettle_hashes[nid]->init)
+    return -1;
+
+  hashes[id].nettle_hash = nettle_hashes[nid];
+  hashes[id].context = Malloc(hashes[id].nettle_hash->context_size);
+
+  return id;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  const struct nettle_hash *hash;
+  void *context;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  hash = hashes[id].nettle_hash;
+  context = hashes[id].context;
+
+  if (out_len > hash->digest_size)
+    out_len = hash->digest_size;
+
+  hash->init(context);
+  hash->update(context, in1_len, in1);
+  if (in2)
+    hash->update(context, in2_len, in2);
+  hash->digest(context, out_len, out);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].context)
+      Free(hashes[i].context);
+  }
+}
diff --git a/hash_nss.c b/hash_nss.c
new file mode 100644
index 0000000..4302447
--- /dev/null
+++ b/hash_nss.c
@@ -0,0 +1,114 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using NSSLOWHASH API of the NSS library.
+
+  */
+
+#include "config.h"
+
+#include <nss.h>
+#include <hasht.h>
+#include <nsslowhash.h>
+
+#include "hash.h"
+#include "util.h"
+
+static NSSLOWInitContext *ictx;
+
+struct hash {
+  HASH_HashType type;
+  HSH_Algorithm algorithm;
+  NSSLOWHASHContext *context;
+};
+
+static struct hash hashes[] = {
+  { HASH_AlgMD5, HSH_MD5, NULL },
+  { HASH_AlgSHA1, HSH_SHA1, NULL },
+  { HASH_AlgSHA256, HSH_SHA256, NULL },
+  { HASH_AlgSHA384, HSH_SHA384, NULL },
+  { HASH_AlgSHA512, HSH_SHA512, NULL },
+  { 0, 0, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int i;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[i].algorithm == 0)
+    return -1; /* not found */
+
+  if (!ictx && !(ictx = NSSLOW_Init()))
+    return -1; /* couldn't init NSS */
+
+  if (!hashes[i].context &&
+      !(hashes[i].context = NSSLOWHASH_NewContext(ictx, hashes[i].type)))
+    return -1; /* couldn't init hash */
+
+  return i;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  unsigned int ret = 0;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  NSSLOWHASH_Begin(hashes[id].context);
+  NSSLOWHASH_Update(hashes[id].context, in1, in1_len);
+  if (in2)
+    NSSLOWHASH_Update(hashes[id].context, in2, in2_len);
+  NSSLOWHASH_End(hashes[id].context, buf, &ret, sizeof (buf));
+
+  ret = MIN(ret, out_len);
+  memcpy(out, buf, ret);
+
+  return ret;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].context)
+      NSSLOWHASH_Destroy(hashes[i].context);
+  }
+
+  if (ictx)
+    NSSLOW_Shutdown(ictx);
+}
diff --git a/hash_tomcrypt.c b/hash_tomcrypt.c
new file mode 100644
index 0000000..9c425d2
--- /dev/null
+++ b/hash_tomcrypt.c
@@ -0,0 +1,126 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012, 2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using tomcrypt library.
+
+  */
+
+#include <tomcrypt.h>
+
+#include "config.h"
+#include "hash.h"
+#include "util.h"
+
+struct hash {
+  HSH_Algorithm algorithm;
+  const char *int_name;
+  const struct ltc_hash_descriptor *desc;
+};
+
+static const struct hash hashes[] = {
+  { HSH_MD5, "md5", &md5_desc },
+#ifdef LTC_SHA1
+  { HSH_SHA1, "sha1", &sha1_desc },
+#endif
+#ifdef LTC_SHA256
+  { HSH_SHA256, "sha256", &sha256_desc },
+#endif
+#ifdef LTC_SHA384
+  { HSH_SHA384, "sha384", &sha384_desc },
+#endif
+#ifdef LTC_SHA512
+  { HSH_SHA512, "sha512", &sha512_desc },
+#endif
+#ifdef LTC_SHA3
+  { HSH_SHA3_224, "sha3-224", &sha3_224_desc },
+  { HSH_SHA3_256, "sha3-256", &sha3_256_desc },
+  { HSH_SHA3_384, "sha3-384", &sha3_384_desc },
+  { HSH_SHA3_512, "sha3-512", &sha3_512_desc },
+#endif
+#ifdef LTC_TIGER
+  { HSH_TIGER, "tiger", &tiger_desc },
+#endif
+#ifdef LTC_WHIRLPOOL
+  { HSH_WHIRLPOOL, "whirlpool", &whirlpool_desc },
+#endif
+  { 0, NULL, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int i, h;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[i].algorithm == 0)
+    return -1; /* not found */
+
+  h = find_hash(hashes[i].int_name);
+  if (h >= 0)
+    return h; /* already registered */
+  
+  /* register and try again */
+  register_hash(hashes[i].desc);
+
+  return find_hash(hashes[i].int_name);
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  unsigned long len;
+  int r;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  len = sizeof (buf);
+  if (in2)
+    r = hash_memory_multi(id, buf, &len,
+                          in1, (unsigned long)in1_len,
+                          in2, (unsigned long)in2_len, NULL, 0);
+  else
+    r = hash_memory(id, in1, in1_len, buf, &len);
+
+  if (r != CRYPT_OK)
+    return 0;
+
+  len = MIN(len, out_len);
+  memcpy(out, buf, len);
+
+  return len;
+}
+
+void
+HSH_Finalise(void)
+{
+}
diff --git a/hwclock.c b/hwclock.c
new file mode 100644
index 0000000..86c7e51
--- /dev/null
+++ b/hwclock.c
@@ -0,0 +1,334 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Tracking of hardware clocks (e.g. RTC, PHC)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "regress.h"
+#include "util.h"
+
+/* Minimum and maximum number of samples per clock */
+#define MIN_SAMPLES 2
+#define MAX_SAMPLES 64
+
+/* Maximum acceptable frequency offset of the clock */
+#define MAX_FREQ_OFFSET (2.0 / 3.0)
+
+/* Quantiles for filtering readings by delay */
+#define DELAY_QUANT_MIN_K 1
+#define DELAY_QUANT_MAX_K 2
+#define DELAY_QUANT_Q 10
+#define DELAY_QUANT_REPEAT 7
+#define DELAY_QUANT_MIN_STEP 1.0e-9
+
+struct HCL_Instance_Record {
+  /* HW and local reference timestamp */
+  struct timespec hw_ref;
+  struct timespec local_ref;
+
+  /* Samples stored as intervals (uncorrected for frequency error)
+     relative to local_ref and hw_ref */
+  double *x_data;
+  double *y_data;
+
+  /* Minimum, maximum and current number of samples */
+  int min_samples;
+  int max_samples;
+  int n_samples;
+
+  /* Maximum error of the last sample */
+  double last_err;
+
+  /* Minimum interval between samples */
+  double min_separation;
+
+  /* Expected precision of readings */
+  double precision;
+
+  /* Flag indicating the offset and frequency values are valid */
+  int valid_coefs;
+
+  /* Estimated offset and frequency of HW clock relative to local clock */
+  double offset;
+  double frequency;
+
+  /* Estimated quantiles of reading delay */
+  QNT_Instance delay_quants;
+};
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  HCL_Instance clock;
+  double delta;
+
+  clock = anything;
+
+  if (clock->n_samples)
+    UTI_AdjustTimespec(&clock->local_ref, cooked, &clock->local_ref, &delta, dfreq, doffset);
+  if (clock->valid_coefs)
+    clock->frequency /= 1.0 - dfreq;
+}
+
+/* ================================================== */
+
+HCL_Instance
+HCL_CreateInstance(int min_samples, int max_samples, double min_separation, double precision)
+{
+  HCL_Instance clock;
+
+  min_samples = CLAMP(MIN_SAMPLES, min_samples, MAX_SAMPLES);
+  max_samples = CLAMP(MIN_SAMPLES, max_samples, MAX_SAMPLES);
+  max_samples = MAX(min_samples, max_samples);
+
+  clock = MallocNew(struct HCL_Instance_Record);
+  clock->x_data = MallocArray(double, max_samples);
+  clock->y_data = MallocArray(double, max_samples);
+  clock->x_data[max_samples - 1] = 0.0;
+  clock->y_data[max_samples - 1] = 0.0;
+  clock->min_samples = min_samples;
+  clock->max_samples = max_samples;
+  clock->n_samples = 0;
+  clock->valid_coefs = 0;
+  clock->min_separation = min_separation;
+  clock->precision = precision;
+  clock->delay_quants = QNT_CreateInstance(DELAY_QUANT_MIN_K, DELAY_QUANT_MAX_K,
+                                           DELAY_QUANT_Q, DELAY_QUANT_REPEAT,
+                                           DELAY_QUANT_MIN_STEP);
+
+  LCL_AddParameterChangeHandler(handle_slew, clock);
+
+  return clock;
+}
+
+/* ================================================== */
+
+void HCL_DestroyInstance(HCL_Instance clock)
+{
+  LCL_RemoveParameterChangeHandler(handle_slew, clock);
+  QNT_DestroyInstance(clock->delay_quants);
+  Free(clock->y_data);
+  Free(clock->x_data);
+  Free(clock);
+}
+
+/* ================================================== */
+
+int
+HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now)
+{
+  if (!clock->n_samples ||
+      fabs(UTI_DiffTimespecsToDouble(now, &clock->local_ref)) >= clock->min_separation)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                    struct timespec *hw_ts, struct timespec *local_ts, double *err)
+{
+  double delay, raw_delay, min_delay, low_delay, high_delay, e, pred_err;
+  double delay_sum, hw_sum, local_sum, local_prec, freq;
+  int i, min_reading, combined;
+  struct timespec ts1, ts2;
+
+  if (n_readings < 1)
+    return 0;
+
+  /* Work out the current correction multiplier needed to get cooked delays */
+  LCL_CookTime(&tss[0][0], &ts1, NULL);
+  LCL_CookTime(&tss[n_readings - 1][2], &ts2, NULL);
+  if (UTI_CompareTimespecs(&tss[0][0], &tss[n_readings - 1][2]) < 0)
+    freq = UTI_DiffTimespecsToDouble(&ts1, &ts2) /
+           UTI_DiffTimespecsToDouble(&tss[0][0], &tss[n_readings - 1][2]);
+  else
+    freq = 1.0;
+
+  for (i = 0; i < n_readings; i++) {
+    delay = freq * UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+
+    if (delay < 0.0) {
+      /* Step in the middle of a reading? */
+      DEBUG_LOG("Bad reading delay=%e", delay);
+      return 0;
+    }
+
+    if (i == 0 || min_delay > delay) {
+      min_delay = delay;
+      min_reading = i;
+    }
+
+    QNT_Accumulate(clock->delay_quants, delay);
+  }
+
+  local_prec = LCL_GetSysPrecisionAsQuantum();
+
+  low_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MIN_K);
+  high_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MAX_K);
+  low_delay = MIN(low_delay, high_delay);
+  high_delay = MAX(high_delay, low_delay + local_prec);
+
+  /* Combine readings with delay in the expected interval */
+  for (i = combined = 0, delay_sum = hw_sum = local_sum = 0.0; i < n_readings; i++) {
+    raw_delay = UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+    delay = freq * raw_delay;
+
+    if (delay < low_delay || delay > high_delay)
+      continue;
+
+    delay_sum += delay;
+    hw_sum += UTI_DiffTimespecsToDouble(&tss[i][1], &tss[0][1]);
+    local_sum += UTI_DiffTimespecsToDouble(&tss[i][0], &tss[0][0]) + raw_delay / 2.0;
+    combined++;
+  }
+
+  DEBUG_LOG("Combined %d readings lo=%e hi=%e", combined, low_delay, high_delay);
+
+  if (combined > 0) {
+    UTI_AddDoubleToTimespec(&tss[0][1], hw_sum / combined, hw_ts);
+    UTI_AddDoubleToTimespec(&tss[0][0], local_sum / combined, local_ts);
+    *err = MAX(delay_sum / combined / 2.0, clock->precision);
+    return 1;
+  }
+
+  /* Accept the reading with minimum delay if its interval does not contain
+     the current offset predicted from previous samples */
+
+  *hw_ts = tss[min_reading][1];
+  UTI_AddDoubleToTimespec(&tss[min_reading][0], min_delay / freq / 2.0, local_ts);
+  *err = MAX(min_delay / 2.0, clock->precision);
+
+  pred_err = 0.0;
+  LCL_CookTime(local_ts, &ts1, NULL);
+  if (!HCL_CookTime(clock, hw_ts, &ts2, &e) ||
+      ((pred_err = UTI_DiffTimespecsToDouble(&ts1, &ts2)) > *err)) {
+    DEBUG_LOG("Accepted reading err=%e prerr=%e", *err, pred_err);
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+void
+HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
+                     struct timespec *local_ts, double err)
+{
+  double hw_delta, local_delta, local_freq, raw_freq;
+  int i, n_runs, best_start;
+
+  local_freq = 1.0 - LCL_ReadAbsoluteFrequency() / 1.0e6;
+
+  /* Shift old samples */
+  if (clock->n_samples) {
+    if (clock->n_samples >= clock->max_samples)
+      clock->n_samples--;
+
+    hw_delta = UTI_DiffTimespecsToDouble(hw_ts, &clock->hw_ref);
+    local_delta = UTI_DiffTimespecsToDouble(local_ts, &clock->local_ref) / local_freq;
+
+    if (hw_delta <= 0.0 || local_delta < clock->min_separation / 2.0) {
+      clock->n_samples = 0;
+      DEBUG_LOG("HW clock reset interval=%f", local_delta);
+    }
+
+    for (i = clock->max_samples - clock->n_samples; i < clock->max_samples; i++) {
+      clock->y_data[i - 1] = clock->y_data[i] - hw_delta;
+      clock->x_data[i - 1] = clock->x_data[i] - local_delta;
+    }
+  }
+
+  clock->n_samples++;
+  clock->hw_ref = *hw_ts;
+  clock->local_ref = *local_ts;
+  clock->last_err = err;
+
+  /* Get new coefficients */
+  clock->valid_coefs =
+    RGR_FindBestRobustRegression(clock->x_data + clock->max_samples - clock->n_samples,
+                                 clock->y_data + clock->max_samples - clock->n_samples,
+                                 clock->n_samples, 1.0e-10, &clock->offset, &raw_freq,
+                                 &n_runs, &best_start);
+
+  if (!clock->valid_coefs) {
+    DEBUG_LOG("HW clock needs more samples");
+    return;
+  }
+
+  clock->frequency = raw_freq / local_freq;
+
+  /* Drop unneeded samples */
+  if (clock->n_samples > clock->min_samples)
+    clock->n_samples -= MIN(best_start, clock->n_samples - clock->min_samples);
+
+  /* If the fit doesn't cross the error interval of the last sample,
+     or the frequency is not sane, drop all samples and start again */
+  if (fabs(clock->offset) > err ||
+      fabs(clock->frequency - 1.0) > MAX_FREQ_OFFSET) {
+    DEBUG_LOG("HW clock reset");
+    clock->n_samples = 0;
+    clock->valid_coefs = 0;
+  }
+
+  DEBUG_LOG("HW clock samples=%d offset=%e freq=%e raw_freq=%e err=%e ref_diff=%e",
+            clock->n_samples, clock->offset, clock->frequency - 1.0, raw_freq - 1.0, err,
+            UTI_DiffTimespecsToDouble(&clock->hw_ref, &clock->local_ref));
+}
+
+/* ================================================== */
+
+int
+HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked, double *err)
+{
+  double offset, elapsed;
+
+  if (!clock->valid_coefs)
+    return 0;
+
+  elapsed = UTI_DiffTimespecsToDouble(raw, &clock->hw_ref);
+  offset = elapsed / clock->frequency - clock->offset;
+  UTI_AddDoubleToTimespec(&clock->local_ref, offset, cooked);
+
+  /* Fow now, just return the error of the last sample */
+  if (err)
+    *err = clock->last_err;
+
+  return 1;
+}
diff --git a/hwclock.h b/hwclock.h
new file mode 100644
index 0000000..c3415ad
--- /dev/null
+++ b/hwclock.h
@@ -0,0 +1,54 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for tracking of hardware clocks */
+
+#ifndef GOT_HWCLOCK_H
+#define GOT_HWCLOCK_H
+
+typedef struct HCL_Instance_Record *HCL_Instance;
+
+/* Create a new HW clock instance */
+extern HCL_Instance HCL_CreateInstance(int min_samples, int max_samples,
+                                       double min_separation, double precision);
+
+/* Destroy a HW clock instance */
+extern void HCL_DestroyInstance(HCL_Instance clock);
+
+/* Check if a new sample should be accumulated at this time */
+extern int HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now);
+
+/* Process new readings of the HW clock in form of (sys, hw, sys) triplets and
+   produce a sample which can be accumulated */
+extern int HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                               struct timespec *hw_ts, struct timespec *local_ts, double *err);
+
+/* Accumulate a new sample */
+extern void HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
+                                 struct timespec *local_ts, double err);
+
+/* Convert raw hardware time to cooked local time */
+extern int HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked,
+                        double *err);
+
+#endif
diff --git a/keys.c b/keys.c
new file mode 100644
index 0000000..cc1131c
--- /dev/null
+++ b/keys.c
@@ -0,0 +1,436 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2012-2016, 2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module for managing keys used for authenticating NTP packets and commands
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "keys.h"
+#include "cmac.h"
+#include "cmdparse.h"
+#include "conf.h"
+#include "memory.h"
+#include "util.h"
+#include "local.h"
+#include "logging.h"
+
+/* Consider 80 bits as the absolute minimum for a secure key */
+#define MIN_SECURE_KEY_LENGTH 10
+
+typedef enum {
+  NTP_MAC,
+  CMAC,
+} KeyClass;
+
+typedef struct {
+  uint32_t id;
+  int type;
+  int length;
+  KeyClass class;
+  union {
+    struct {
+      unsigned char *value;
+      int hash_id;
+    } ntp_mac;
+    CMC_Instance cmac;
+  } data;
+} Key;
+
+static ARR_Instance keys;
+
+static int cache_valid;
+static uint32_t cache_key_id;
+static int cache_key_pos;
+
+/* ================================================== */
+
+static void
+free_keys(void)
+{
+  unsigned int i;
+  Key *key;
+
+  for (i = 0; i < ARR_GetSize(keys); i++) {
+    key = ARR_GetElement(keys, i);
+    switch (key->class) {
+      case NTP_MAC:
+        Free(key->data.ntp_mac.value);
+        break;
+      case CMAC:
+        CMC_DestroyInstance(key->data.cmac);
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  ARR_SetSize(keys, 0);
+  cache_valid = 0;
+}
+
+/* ================================================== */
+
+void
+KEY_Initialise(void)
+{
+  keys = ARR_CreateInstance(sizeof (Key));
+  cache_valid = 0;
+  KEY_Reload();
+}
+
+/* ================================================== */
+
+void
+KEY_Finalise(void)
+{
+  free_keys();
+  ARR_DestroyInstance(keys);
+}
+
+/* ================================================== */
+
+static Key *
+get_key(unsigned int index)
+{
+  return ((Key *)ARR_GetElements(keys)) + index;
+}
+
+/* ================================================== */
+/* Decode key encoded in ASCII or HEX */
+
+static int
+decode_key(char *key)
+{
+  int len = strlen(key);
+
+  if (!strncmp(key, "ASCII:", 6)) {
+    memmove(key, key + 6, len - 6);
+    return len - 6;
+  } else if (!strncmp(key, "HEX:", 4)) {
+    return UTI_HexToBytes(key + 4, key, len);
+  } else {
+    /* assume ASCII */
+    return len;
+  }
+}
+
+/* ================================================== */
+
+/* Compare two keys */
+
+static int
+compare_keys_by_id(const void *a, const void *b)
+{
+  const Key *c = (const Key *) a;
+  const Key *d = (const Key *) b;
+
+  if (c->id < d->id) {
+    return -1;
+  } else if (c->id > d->id) {
+    return +1;
+  } else {
+    return 0;
+  }
+
+}
+
+/* ================================================== */
+
+void
+KEY_Reload(void)
+{
+  unsigned int i, line_number, key_length, cmac_key_length;
+  FILE *in;
+  char line[2048], *key_file, *key_value;
+  const char *key_type;
+  HSH_Algorithm hash_algorithm;
+  CMC_Algorithm cmac_algorithm;
+  int hash_id;
+  Key key;
+
+  free_keys();
+
+  key_file = CNF_GetKeysFile();
+  line_number = 0;
+
+  if (!key_file)
+    return;
+
+  in = UTI_OpenFile(NULL, key_file, NULL, 'r', 0);
+  if (!in) {
+    LOG(LOGS_WARN, "Could not open keyfile %s", key_file);
+    return;
+  }
+
+  while (fgets(line, sizeof (line), in)) {
+    line_number++;
+
+    CPS_NormalizeLine(line);
+    if (!*line)
+      continue;
+
+    memset(&key, 0, sizeof (key));
+
+    if (!CPS_ParseKey(line, &key.id, &key_type, &key_value)) {
+      LOG(LOGS_WARN, "Could not parse key at line %u in file %s", line_number, key_file);
+      continue;
+    }
+
+    key_length = decode_key(key_value);
+    if (key_length == 0) {
+      LOG(LOGS_WARN, "Could not decode key %"PRIu32, key.id);
+      continue;
+    }
+
+    hash_algorithm = UTI_HashNameToAlgorithm(key_type);
+    cmac_algorithm = UTI_CmacNameToAlgorithm(key_type);
+
+    if (hash_algorithm != 0) {
+      hash_id = HSH_GetHashId(hash_algorithm);
+      if (hash_id < 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "hash function", key.id);
+        continue;
+      }
+      key.class = NTP_MAC;
+      key.type = hash_algorithm;
+      key.length = key_length;
+      key.data.ntp_mac.value = MallocArray(unsigned char, key_length);
+      memcpy(key.data.ntp_mac.value, key_value, key_length);
+      key.data.ntp_mac.hash_id = hash_id;
+    } else if (cmac_algorithm != 0) {
+      cmac_key_length = CMC_GetKeyLength(cmac_algorithm);
+      if (cmac_key_length == 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "cipher", key.id);
+        continue;
+      } else if (cmac_key_length != key_length) {
+        LOG(LOGS_WARN, "Invalid length of %s key %"PRIu32" (expected %u bits)",
+            key_type, key.id, 8 * cmac_key_length);
+        continue;
+      }
+
+      key.class = CMAC;
+      key.type = cmac_algorithm;
+      key.length = key_length;
+      key.data.cmac = CMC_CreateInstance(cmac_algorithm, (unsigned char *)key_value,
+                                         key_length);
+      assert(key.data.cmac);
+    } else {
+      LOG(LOGS_WARN, "Invalid type in key %"PRIu32, key.id);
+      continue;
+    }
+
+    ARR_AppendElement(keys, &key);
+  }
+
+  fclose(in);
+
+  /* Sort keys into order.  Note, if there's a duplicate, it is
+     arbitrary which one we use later - the user should have been
+     more careful! */
+  qsort(ARR_GetElements(keys), ARR_GetSize(keys), sizeof (Key), compare_keys_by_id);
+
+  /* Check for duplicates */
+  for (i = 1; i < ARR_GetSize(keys); i++) {
+    if (get_key(i - 1)->id == get_key(i)->id)
+      LOG(LOGS_WARN, "Detected duplicate key %"PRIu32, get_key(i - 1)->id);
+  }
+
+  /* Erase any passwords from stack */
+  memset(line, 0, sizeof (line));
+}
+
+/* ================================================== */
+
+static int
+lookup_key(uint32_t id)
+{
+  Key specimen, *where, *keys_ptr;
+  int pos;
+
+  keys_ptr = ARR_GetElements(keys);
+  specimen.id = id;
+  where = (Key *)bsearch((void *)&specimen, keys_ptr, ARR_GetSize(keys),
+                         sizeof (Key), compare_keys_by_id);
+  if (!where) {
+    return -1;
+  } else {
+    pos = where - keys_ptr;
+    return pos;
+  }
+}
+
+/* ================================================== */
+
+static Key *
+get_key_by_id(uint32_t key_id)
+{
+  int position;
+
+  if (cache_valid && key_id == cache_key_id)
+    return get_key(cache_key_pos);
+
+  position = lookup_key(key_id);
+
+  if (position >= 0) {
+    cache_valid = 1;
+    cache_key_pos = position;
+    cache_key_id = key_id;
+
+    return get_key(position);
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+KEY_KeyKnown(uint32_t key_id)
+{
+  return get_key_by_id(key_id) != NULL;
+}
+
+/* ================================================== */
+
+int
+KEY_GetAuthLength(uint32_t key_id)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  switch (key->class) {
+    case NTP_MAC:
+      return HSH_Hash(key->data.ntp_mac.hash_id, buf, 0, buf, 0, buf, sizeof (buf));
+    case CMAC:
+      return CMC_Hash(key->data.cmac, buf, 0, buf, sizeof (buf));
+    default:
+      assert(0);
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+KEY_CheckKeyLength(uint32_t key_id)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return key->length >= MIN_SECURE_KEY_LENGTH;
+}
+
+/* ================================================== */
+
+int
+KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  *type = key->type;
+  *bits = 8 * key->length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+generate_auth(Key *key, const void *data, int data_len, unsigned char *auth, int auth_len)
+{
+  switch (key->class) {
+    case NTP_MAC:
+      return HSH_Hash(key->data.ntp_mac.hash_id, key->data.ntp_mac.value,
+                      key->length, data, data_len, auth, auth_len);
+    case CMAC:
+      return CMC_Hash(key->data.cmac, data, data_len, auth, auth_len);
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+check_auth(Key *key, const void *data, int data_len,
+           const unsigned char *auth, int auth_len, int trunc_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  int hash_len;
+
+  hash_len = generate_auth(key, data, data_len, buf, sizeof (buf));
+
+  return MIN(hash_len, trunc_len) == auth_len && !memcmp(buf, auth, auth_len);
+}
+
+/* ================================================== */
+
+int
+KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
+                 unsigned char *auth, int auth_len)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return generate_auth(key, data, data_len, auth, auth_len);
+}
+
+/* ================================================== */
+
+int
+KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
+              const unsigned char *auth, int auth_len, int trunc_len)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return check_auth(key, data, data_len, auth, auth_len, trunc_len);
+}
diff --git a/keys.h b/keys.h
new file mode 100644
index 0000000..c89fea9
--- /dev/null
+++ b/keys.h
@@ -0,0 +1,47 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for key management module
+  */
+
+#ifndef GOT_KEYS_H
+#define GOT_KEYS_H
+
+#include "sysincl.h"
+
+extern void KEY_Initialise(void);
+extern void KEY_Finalise(void);
+
+extern void KEY_Reload(void);
+
+extern int KEY_KeyKnown(uint32_t key_id);
+extern int KEY_GetAuthLength(uint32_t key_id);
+extern int KEY_CheckKeyLength(uint32_t key_id);
+extern int KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits);
+
+extern int KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
+                            unsigned char *auth, int auth_len);
+extern int KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
+                         const unsigned char *auth, int auth_len, int trunc_len);
+
+#endif /* GOT_KEYS_H */
diff --git a/local.c b/local.c
new file mode 100644
index 0000000..b32d0c6
--- /dev/null
+++ b/local.c
@@ -0,0 +1,781 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2014-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The routines in this file present a common local (system) clock
+  interface to the rest of the software.
+
+  They interface with the system specific driver files in sys_*.c
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "memory.h"
+#include "smooth.h"
+#include "util.h"
+#include "logging.h"
+
+/* ================================================== */
+
+/* Variable to store the current frequency, in ppm */
+static double current_freq_ppm;
+
+/* Maximum allowed frequency, in ppm */
+static double max_freq_ppm;
+
+/* Temperature compensation, in ppm */
+static double temp_comp_ppm;
+
+/* ================================================== */
+/* Store the system dependent drivers */
+
+static lcl_ReadFrequencyDriver drv_read_freq;
+static lcl_SetFrequencyDriver drv_set_freq;
+static lcl_AccrueOffsetDriver drv_accrue_offset;
+static lcl_ApplyStepOffsetDriver drv_apply_step_offset;
+static lcl_OffsetCorrectionDriver drv_offset_convert;
+static lcl_SetLeapDriver drv_set_leap;
+static lcl_SetSyncStatusDriver drv_set_sync_status;
+
+/* ================================================== */
+
+/* Types and variables associated with handling the parameter change
+   list */
+
+typedef struct _ChangeListEntry {
+  struct _ChangeListEntry *next;
+  struct _ChangeListEntry *prev;
+  LCL_ParameterChangeHandler handler;
+  void *anything;
+} ChangeListEntry;
+
+static ChangeListEntry change_list;
+
+/* ================================================== */
+
+/* Types and variables associated with handling the parameter change
+   list */
+
+typedef struct _DispersionNotifyListEntry {
+  struct _DispersionNotifyListEntry *next;
+  struct _DispersionNotifyListEntry *prev;
+  LCL_DispersionNotifyHandler handler;
+  void *anything;
+} DispersionNotifyListEntry;
+
+static DispersionNotifyListEntry dispersion_notify_list;
+
+/* ================================================== */
+
+static int precision_log;
+static double precision_quantum;
+
+static double max_clock_error;
+
+/* ================================================== */
+
+/* Define the number of increments of the system clock that we want
+   to see to be fairly sure that we've got something approaching
+   the minimum increment.  Even on a crummy implementation that can't
+   interpolate between 10ms ticks, we should get this done in
+   under 1s of busy waiting. */
+#define NITERS 100
+
+#define NSEC_PER_SEC 1000000000
+
+static double
+measure_clock_precision(void)
+{
+  struct timespec ts, old_ts;
+  int iters, diff, best;
+
+  LCL_ReadRawTime(&old_ts);
+
+  /* Assume we must be better than a second */
+  best = NSEC_PER_SEC;
+  iters = 0;
+
+  do {
+    LCL_ReadRawTime(&ts);
+
+    diff = NSEC_PER_SEC * (ts.tv_sec - old_ts.tv_sec) + (ts.tv_nsec - old_ts.tv_nsec);
+
+    old_ts = ts;
+    if (diff > 0) {
+      if (diff < best)
+        best = diff;
+      iters++;
+    }
+  } while (iters < NITERS);
+
+  assert(best > 0);
+
+  return 1.0e-9 * best;
+}
+
+/* ================================================== */
+
+void
+LCL_Initialise(void)
+{
+  change_list.next = change_list.prev = &change_list;
+
+  dispersion_notify_list.next = dispersion_notify_list.prev = &dispersion_notify_list;
+
+  /* Null out the system drivers, so that we die
+     if they never get defined before use */
+  
+  drv_read_freq = NULL;
+  drv_set_freq = NULL;
+  drv_accrue_offset = NULL;
+  drv_offset_convert = NULL;
+
+  /* This ought to be set from the system driver layer */
+  current_freq_ppm = 0.0;
+  temp_comp_ppm = 0.0;
+
+  precision_quantum = CNF_GetClockPrecision();
+  if (precision_quantum <= 0.0)
+    precision_quantum = measure_clock_precision();
+
+  precision_quantum = CLAMP(1.0e-9, precision_quantum, 1.0);
+  precision_log = round(log(precision_quantum) / log(2.0));
+  /* NTP code doesn't support smaller log than -30 */
+  assert(precision_log >= -30);
+
+  DEBUG_LOG("Clock precision %.9f (%d)", precision_quantum, precision_log);
+
+  /* This is the maximum allowed frequency offset in ppm, the time must
+     never stop or run backwards */
+  max_freq_ppm = CNF_GetMaxDrift();
+  max_freq_ppm = CLAMP(0.0, max_freq_ppm, 500000.0);
+
+  max_clock_error = CNF_GetMaxClockError() * 1e-6;
+}
+
+/* ================================================== */
+
+void
+LCL_Finalise(void)
+{
+  /* Make sure all handlers have been removed */
+  if (change_list.next != &change_list)
+    assert(0);
+  if (dispersion_notify_list.next != &dispersion_notify_list)
+    assert(0);
+}
+
+/* ================================================== */
+
+/* Routine to read the system precision as a log to base 2 value. */
+int
+LCL_GetSysPrecisionAsLog(void)
+{
+  return precision_log;
+}
+
+/* ================================================== */
+/* Routine to read the system precision in terms of the actual time step */
+
+double
+LCL_GetSysPrecisionAsQuantum(void)
+{
+  return precision_quantum;
+}
+
+/* ================================================== */
+
+double
+LCL_GetMaxClockError(void)
+{
+  return max_clock_error;
+}
+
+/* ================================================== */
+
+void
+LCL_AddParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything)
+{
+  ChangeListEntry *ptr, *new_entry;
+
+  /* Check that the handler is not already registered */
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    if (!(ptr->handler != handler || ptr->anything != anything)) {
+      assert(0);
+    }
+  }
+
+  new_entry = MallocNew(ChangeListEntry);
+
+  new_entry->handler = handler;
+  new_entry->anything = anything;
+
+  /* Chain it into the list */
+  new_entry->next = &change_list;
+  new_entry->prev = change_list.prev;
+  change_list.prev->next = new_entry;
+  change_list.prev = new_entry;
+}
+
+/* ================================================== */
+
+/* Remove a handler */
+void LCL_RemoveParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything)
+{
+
+  ChangeListEntry *ptr;
+  int ok;
+
+  ptr = NULL;
+  ok = 0;
+
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    if (ptr->handler == handler && ptr->anything == anything) {
+      ok = 1;
+      break;
+    }
+  }
+
+  assert(ok);
+
+  /* Unlink entry from the list */
+  ptr->next->prev = ptr->prev;
+  ptr->prev->next = ptr->next;
+
+  Free(ptr);
+}
+
+/* ================================================== */
+
+int
+LCL_IsFirstParameterChangeHandler(LCL_ParameterChangeHandler handler)
+{
+  return change_list.next->handler == handler;
+}
+
+/* ================================================== */
+
+static void
+invoke_parameter_change_handlers(struct timespec *raw, struct timespec *cooked,
+                                 double dfreq, double doffset,
+                                 LCL_ChangeType change_type)
+{
+  ChangeListEntry *ptr;
+
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    (ptr->handler)(raw, cooked, dfreq, doffset, change_type, ptr->anything);
+  }
+}
+
+/* ================================================== */
+
+void
+LCL_AddDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything)
+{
+  DispersionNotifyListEntry *ptr, *new_entry;
+
+  /* Check that the handler is not already registered */
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    if (!(ptr->handler != handler || ptr->anything != anything)) {
+      assert(0);
+    }
+  }
+
+  new_entry = MallocNew(DispersionNotifyListEntry);
+
+  new_entry->handler = handler;
+  new_entry->anything = anything;
+
+  /* Chain it into the list */
+  new_entry->next = &dispersion_notify_list;
+  new_entry->prev = dispersion_notify_list.prev;
+  dispersion_notify_list.prev->next = new_entry;
+  dispersion_notify_list.prev = new_entry;
+}
+
+/* ================================================== */
+
+/* Remove a handler */
+extern 
+void LCL_RemoveDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything)
+{
+
+  DispersionNotifyListEntry *ptr;
+  int ok;
+
+  ptr = NULL;
+  ok = 0;
+
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    if (ptr->handler == handler && ptr->anything == anything) {
+      ok = 1;
+      break;
+    }
+  }
+
+  assert(ok);
+
+  /* Unlink entry from the list */
+  ptr->next->prev = ptr->prev;
+  ptr->prev->next = ptr->next;
+
+  Free(ptr);
+}
+
+/* ================================================== */
+
+void
+LCL_ReadRawTime(struct timespec *ts)
+{
+#if HAVE_CLOCK_GETTIME
+  if (clock_gettime(CLOCK_REALTIME, ts) < 0)
+    LOG_FATAL("clock_gettime() failed : %s", strerror(errno));
+#else
+  struct timeval tv;
+
+  if (gettimeofday(&tv, NULL) < 0)
+    LOG_FATAL("gettimeofday() failed : %s", strerror(errno));
+
+  UTI_TimevalToTimespec(&tv, ts);
+#endif
+}
+
+/* ================================================== */
+
+void
+LCL_ReadCookedTime(struct timespec *result, double *err)
+{
+  struct timespec raw;
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, result, err);
+}
+
+/* ================================================== */
+
+void
+LCL_CookTime(struct timespec *raw, struct timespec *cooked, double *err)
+{
+  double correction;
+
+  LCL_GetOffsetCorrection(raw, &correction, err);
+  UTI_AddDoubleToTimespec(raw, correction, cooked);
+}
+
+/* ================================================== */
+
+void
+LCL_GetOffsetCorrection(struct timespec *raw, double *correction, double *err)
+{
+  /* Call system specific driver to get correction */
+  (*drv_offset_convert)(raw, correction, err);
+}
+
+/* ================================================== */
+/* Return current frequency */
+
+double
+LCL_ReadAbsoluteFrequency(void)
+{
+  double freq;
+
+  freq = current_freq_ppm; 
+
+  /* Undo temperature compensation */
+  if (temp_comp_ppm != 0.0) {
+    freq = (freq + temp_comp_ppm) / (1.0 - 1.0e-6 * temp_comp_ppm);
+  }
+
+  return freq;
+}
+
+/* ================================================== */
+
+static double
+clamp_freq(double freq)
+{
+  if (freq <= max_freq_ppm && freq >= -max_freq_ppm)
+    return freq;
+
+  LOG(LOGS_WARN, "Frequency %.1f ppm exceeds allowed maximum", freq);
+
+  return CLAMP(-max_freq_ppm, freq, max_freq_ppm);
+}
+
+/* ================================================== */
+
+static int
+check_offset(struct timespec *now, double offset)
+{
+  /* Check if the time will be still sane with accumulated offset */
+  if (UTI_IsTimeOffsetSane(now, -offset))
+      return 1;
+
+  LOG(LOGS_WARN, "Adjustment of %.1f seconds is invalid", -offset);
+  return 0;
+}
+
+/* ================================================== */
+
+/* This involves both setting the absolute frequency with the
+   system-specific driver, as well as calling all notify handlers */
+
+void
+LCL_SetAbsoluteFrequency(double afreq_ppm)
+{
+  struct timespec raw, cooked;
+  double dfreq;
+  
+  afreq_ppm = clamp_freq(afreq_ppm);
+
+  /* Apply temperature compensation */
+  if (temp_comp_ppm != 0.0) {
+    afreq_ppm = afreq_ppm * (1.0 - 1.0e-6 * temp_comp_ppm) - temp_comp_ppm;
+  }
+
+  /* Call the system-specific driver for setting the frequency */
+  
+  afreq_ppm = (*drv_set_freq)(afreq_ppm);
+
+  dfreq = (afreq_ppm - current_freq_ppm) / (1.0e6 - current_freq_ppm);
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, 0.0, LCL_ChangeAdjust);
+
+  current_freq_ppm = afreq_ppm;
+
+}
+
+/* ================================================== */
+
+void
+LCL_AccumulateDeltaFrequency(double dfreq)
+{
+  struct timespec raw, cooked;
+  double old_freq_ppm;
+
+  old_freq_ppm = current_freq_ppm;
+
+  /* Work out new absolute frequency.  Note that absolute frequencies
+   are handled in units of ppm, whereas the 'dfreq' argument is in
+   terms of the gradient of the (offset) v (local time) function. */
+
+  current_freq_ppm += dfreq * (1.0e6 - current_freq_ppm);
+
+  current_freq_ppm = clamp_freq(current_freq_ppm);
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, 0.0, LCL_ChangeAdjust);
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateOffset(double offset, double corr_rate)
+{
+  struct timespec raw, cooked;
+
+  /* In this case, the cooked time to be passed to the notify clients
+     has to be the cooked time BEFORE the change was made */
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&cooked, offset))
+    return 0;
+
+  (*drv_accrue_offset)(offset, corr_rate);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, offset, LCL_ChangeAdjust);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+LCL_ApplyStepOffset(double offset)
+{
+  struct timespec raw, cooked;
+
+  /* In this case, the cooked time to be passed to the notify clients
+     has to be the cooked time BEFORE the change was made */
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&raw, offset))
+      return 0;
+
+  if (!(*drv_apply_step_offset)(offset)) {
+    LOG(LOGS_ERR, "Could not step system clock");
+    return 0;
+  }
+
+  /* Reset smoothing on all clock steps */
+  SMT_Reset(&cooked);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, offset, LCL_ChangeStep);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
+    double offset, double dispersion)
+{
+  LCL_CancelOffsetCorrection();
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(raw, cooked, 0.0, offset, LCL_ChangeUnknownStep);
+
+  lcl_InvokeDispersionNotifyHandlers(dispersion);
+}
+
+/* ================================================== */
+
+void
+LCL_NotifyLeap(int leap)
+{
+  struct timespec raw, cooked;
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Smooth the leap second out */
+  SMT_Leap(&cooked, leap);
+
+  /* Dispatch to all handlers as if the clock was stepped */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, -leap, LCL_ChangeStep);
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)
+{
+  struct timespec raw, cooked;
+  double old_freq_ppm;
+
+  LCL_ReadRawTime(&raw);
+  /* Due to modifying the offset, this has to be the cooked time prior
+     to the change we are about to make */
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&cooked, doffset))
+    return 0;
+
+  old_freq_ppm = current_freq_ppm;
+
+  /* Work out new absolute frequency.  Note that absolute frequencies
+   are handled in units of ppm, whereas the 'dfreq' argument is in
+   terms of the gradient of the (offset) v (local time) function. */
+  current_freq_ppm += dfreq * (1.0e6 - current_freq_ppm);
+
+  current_freq_ppm = clamp_freq(current_freq_ppm);
+
+  DEBUG_LOG("old_freq=%.3fppm new_freq=%.3fppm offset=%.6fsec",
+      old_freq_ppm, current_freq_ppm, doffset);
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
+
+  (*drv_accrue_offset)(doffset, corr_rate);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, doffset, LCL_ChangeAdjust);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset, double corr_rate)
+{
+  ChangeListEntry *first_handler;
+  int r;
+
+  first_handler = change_list.next;
+  change_list.next = &change_list;
+
+  r = LCL_AccumulateFrequencyAndOffset(dfreq, doffset, corr_rate);
+
+  change_list.next = first_handler;
+
+  return r;
+}
+
+/* ================================================== */
+
+void
+lcl_InvokeDispersionNotifyHandlers(double dispersion)
+{
+  DispersionNotifyListEntry *ptr;
+
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    (ptr->handler)(dispersion, ptr->anything);
+  }
+
+}
+
+/* ================================================== */
+
+void
+lcl_RegisterSystemDrivers(lcl_ReadFrequencyDriver read_freq,
+                          lcl_SetFrequencyDriver set_freq,
+                          lcl_AccrueOffsetDriver accrue_offset,
+                          lcl_ApplyStepOffsetDriver apply_step_offset,
+                          lcl_OffsetCorrectionDriver offset_convert,
+                          lcl_SetLeapDriver set_leap,
+                          lcl_SetSyncStatusDriver set_sync_status)
+{
+  drv_read_freq = read_freq;
+  drv_set_freq = set_freq;
+  drv_accrue_offset = accrue_offset;
+  drv_apply_step_offset = apply_step_offset;
+  drv_offset_convert = offset_convert;
+  drv_set_leap = set_leap;
+  drv_set_sync_status = set_sync_status;
+
+  current_freq_ppm = (*drv_read_freq)();
+
+  DEBUG_LOG("Local freq=%.3fppm", current_freq_ppm);
+}
+
+/* ================================================== */
+/* Look at the current difference between the system time and the NTP
+   time, and make a step to cancel it. */
+
+int
+LCL_MakeStep(void)
+{
+  struct timespec raw;
+  double correction;
+
+  LCL_ReadRawTime(&raw);
+  LCL_GetOffsetCorrection(&raw, &correction, NULL);
+
+  if (!check_offset(&raw, -correction))
+      return 0;
+
+  /* Cancel remaining slew and make the step */
+  LCL_AccumulateOffset(correction, 0.0);
+  if (!LCL_ApplyStepOffset(-correction))
+    return 0;
+
+  LOG(LOGS_WARN, "System clock was stepped by %.6f seconds", correction);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+LCL_CancelOffsetCorrection(void)
+{
+  struct timespec raw;
+  double correction;
+
+  LCL_ReadRawTime(&raw);
+  LCL_GetOffsetCorrection(&raw, &correction, NULL);
+  LCL_AccumulateOffset(correction, 0.0);
+}
+
+/* ================================================== */
+
+int
+LCL_CanSystemLeap(void)
+{
+  return drv_set_leap ? 1 : 0;
+}
+
+/* ================================================== */
+
+void
+LCL_SetSystemLeap(int leap, int tai_offset)
+{
+  if (drv_set_leap) {
+    (drv_set_leap)(leap, tai_offset);
+  }
+}
+
+/* ================================================== */
+
+double
+LCL_SetTempComp(double comp)
+{
+  double uncomp_freq_ppm;
+
+  if (temp_comp_ppm == comp)
+    return comp;
+
+  /* Undo previous compensation */
+  current_freq_ppm = (current_freq_ppm + temp_comp_ppm) /
+    (1.0 - 1.0e-6 * temp_comp_ppm);
+
+  uncomp_freq_ppm = current_freq_ppm;
+
+  /* Apply new compensation */
+  current_freq_ppm = current_freq_ppm * (1.0 - 1.0e-6 * comp) - comp;
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+
+  temp_comp_ppm = (uncomp_freq_ppm - current_freq_ppm) /
+    (1.0e-6 * uncomp_freq_ppm + 1.0);
+
+  return temp_comp_ppm;
+}
+
+/* ================================================== */
+
+void
+LCL_SetSyncStatus(int synchronised, double est_error, double max_error)
+{
+  if (drv_set_sync_status) {
+    (drv_set_sync_status)(synchronised, est_error, max_error);
+  }
+}
+
+/* ================================================== */
diff --git a/local.h b/local.h
new file mode 100644
index 0000000..a23d275
--- /dev/null
+++ b/local.h
@@ -0,0 +1,229 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module provides an interface to the system time, and
+  insulates the rest of the program from the different way
+  that interface has to be done on various operating systems.
+  */
+
+#ifndef GOT_LOCAL_H
+#define GOT_LOCAL_H
+
+#include "sysincl.h"
+
+/* Read the system clock */
+extern void LCL_ReadRawTime(struct timespec *ts);
+
+/* Read the system clock, corrected according to all accumulated
+   drifts and uncompensated offsets.
+
+   In a kernel implementation with vernier frequency control (like
+   Linux), and if we were to apply offsets by stepping the clock, this
+   would be identical to raw time.  In any other case (use of
+   adjtime()-like interface to correct offsets, and to adjust the
+   frequency), we must correct the raw time to get this value */
+
+extern void LCL_ReadCookedTime(struct timespec *ts, double *err);
+
+/* Convert raw time to cooked. */
+extern void LCL_CookTime(struct timespec *raw, struct timespec *cooked, double *err);
+
+/* Read the current offset between the system clock and true time
+   (i.e. 'cooked' - 'raw') (in seconds). */
+
+extern void LCL_GetOffsetCorrection(struct timespec *raw, double *correction, double *err);
+
+/* Type of routines that may be invoked as callbacks when there is a
+   change to the frequency or offset.
+
+   raw : raw local clock time at which change occurred
+
+   cooked : cooked local time at which change occurred
+
+   dfreq : delta frequency relative to previous value (in terms of
+   seconds gained by system clock per unit system clock time)
+
+   doffset : delta offset applied (positive => make local system fast
+   by that amount, negative => make it slow by that amount)
+
+   change_type : what type of change is being applied
+   
+   anything : Passthrough argument from call to registration routine */
+
+
+typedef enum {
+  LCL_ChangeAdjust,
+  LCL_ChangeStep,
+  LCL_ChangeUnknownStep
+} LCL_ChangeType;
+
+typedef void (*LCL_ParameterChangeHandler)
+     (struct timespec *raw, struct timespec *cooked,
+      double dfreq,
+      double doffset,
+      LCL_ChangeType change_type,
+      void *anything
+      );
+
+/* Add a handler.  Then handler MUST NOT deregister itself!!! */
+extern void LCL_AddParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything);
+
+/* Remove a handler */
+extern void LCL_RemoveParameterChangeHandler(LCL_ParameterChangeHandler, void *anything);
+
+/* Check if a handler is invoked first when dispatching */
+extern int LCL_IsFirstParameterChangeHandler(LCL_ParameterChangeHandler handler);
+
+/* Function type for handlers to be called back when an indeterminate
+   offset is introduced into the local time.  This situation occurs
+   when the frequency must be adjusted to effect a clock slew and
+   there is doubt about one of the endpoints of the interval over
+   which the frequency change was applied.It is expected that such
+   handlers will add extra dispersion to any existing samples stored
+   in their registers. 
+
+   dispersion : The bound on how much error has been introduced in the
+   local clock, in seconds.
+
+   anything : passthrough from the registration routine
+
+   */
+
+typedef void (*LCL_DispersionNotifyHandler)(double dispersion, void *anything);
+
+/* Register a handler for being notified of dispersion being added to
+   the local clock.  The handler MUST NOT unregister itself!!! */
+
+extern void LCL_AddDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
+
+/* Delete a handler */
+
+extern void LCL_RemoveDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
+
+
+/* Read the absolute system frequency, relative to the uncompensated
+   system.  Returned in units of parts per million.  Thus the result of
+   this is how many seconds fast the uncompensated system would be after
+   its own time has reached 1 million seconds from the start of the
+   measurement.  */
+extern double LCL_ReadAbsoluteFrequency(void);
+
+/* Routine to set the absolute frequency.  Only expected to be used
+   when either (i) reading the drift from a file at the start of a
+   run, or (ii) responsing to a user parameter 'poke'.  This is
+   defined in ppm, as for the absolute frequency reading routine. */
+
+extern void LCL_SetAbsoluteFrequency(double afreq);
+
+/* Routine to apply a change of frequency to the local clock.  The
+   argument is the estimated gain (positive) or loss (negative) of the
+   local clock relative to true time, per unit time of the PREVIOUS
+   frequency setting of the local clock.  This is assumed to be based
+   on a regression of y=offset v x=cooked local time. */
+
+extern void LCL_AccumulateDeltaFrequency(double dfreq);
+
+/* Routine to apply an offset (in seconds) to the local clock.  The
+   argument should be positive to move the clock backwards (i.e. the
+   local clock is currently fast of true time), or negative to move it
+   forwards (i.e. it is currently slow of true time).  Provided is also
+   a suggested correction rate (correction time * offset). */
+
+extern int LCL_AccumulateOffset(double offset, double corr_rate);
+
+/* Routine to apply an immediate offset by doing a sudden step if
+   possible. (Intended for use after an initial estimate of offset has
+   been obtained, so that we don't end up using adjtime to achieve a
+   slew of an hour or something like that). A positive argument means
+   the system clock is fast on true time, i.e. it needs to be stepped
+   backwards. (Same convention as for AccumulateOffset routine). */
+
+extern int LCL_ApplyStepOffset(double offset);
+
+/* Routine to invoke notify handlers on an unexpected time jump
+   in system clock */
+extern void LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
+    double offset, double dispersion);
+
+/* Routine to invoke notify handlers on leap second when the system clock
+   doesn't correct itself */
+extern void LCL_NotifyLeap(int leap);
+
+/* Perform the combination of modifying the frequency and applying
+   a slew, in one easy step */
+extern int LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate);
+
+/* Same as the routine above, except it does not call the registered
+   parameter change handlers */
+extern int LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset,
+                                                      double corr_rate);
+
+/* Routine to read the system precision as a log to base 2 value. */
+extern int LCL_GetSysPrecisionAsLog(void);
+
+/* Routine to read the system precision in terms of the actual time step */
+extern double LCL_GetSysPrecisionAsQuantum(void);
+
+/* Routine to read the maximum frequency error of the local clock.  This
+   is a frequency stability, not an absolute error. */
+extern double LCL_GetMaxClockError(void);
+
+/* Routine to initialise the module (to be called once at program
+   start-up) */
+
+extern void LCL_Initialise(void);
+
+/* Routine to finalise the module (to be called once at end of
+   run). */
+extern void LCL_Finalise(void);
+
+/* Routine to convert the outstanding system clock error to a step and
+   apply it, e.g. if the system clock has ended up an hour wrong due
+   to a timezone problem. */
+extern int LCL_MakeStep(void);
+
+/* Routine to cancel the outstanding system clock correction */
+extern void LCL_CancelOffsetCorrection(void);
+
+/* Check if the system driver supports leap seconds, i.e. LCL_SetSystemLeap
+   does something */
+extern int LCL_CanSystemLeap(void);
+
+/* Routine to set the system clock to correct itself for a leap second and also
+   set its TAI-UTC offset.  If supported, leap second will be inserted at the
+   end of the day if the argument is positive, deleted if negative, and zero
+   resets the setting. */
+extern void LCL_SetSystemLeap(int leap, int tai_offset);
+
+/* Routine to set a frequency correction (in ppm) that should be applied
+   to local clock to compensate for temperature changes.  A positive
+   argument means that the clock frequency should be increased. Return the
+   actual compensation (may be different from the requested compensation
+   due to clamping or rounding). */
+extern double LCL_SetTempComp(double comp);
+
+/* Routine to update the synchronisation status in the kernel to allow other
+   applications to know if the system clock is synchronised and error bounds */
+extern void LCL_SetSyncStatus(int synchronised, double est_error, double max_error);
+
+#endif /* GOT_LOCAL_H */
diff --git a/localp.h b/localp.h
new file mode 100644
index 0000000..6f65e43
--- /dev/null
+++ b/localp.h
@@ -0,0 +1,74 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Private include file for local.c and all system dependent
+  driver modules.
+  */
+
+
+#ifndef GOT_LOCALP_H
+#define GOT_LOCALP_H
+
+/* System driver to read the current local frequency, in ppm relative
+   to nominal.  A positive value indicates that the local clock runs
+   fast when uncompensated. */
+typedef double (*lcl_ReadFrequencyDriver)(void);
+
+/* System driver to set the current local frequency, in ppm relative
+   to nominal.  A positive value indicates that the local clock runs
+   fast when uncompensated.  Return actual frequency (may be different
+   from the requested frequency due to clamping or rounding). */
+typedef double (*lcl_SetFrequencyDriver)(double freq_ppm);
+
+/* System driver to accrue an offset. A positive argument means slew
+   the clock forwards.  The suggested correction rate of time to correct the
+   offset is given in 'corr_rate'. */
+typedef void (*lcl_AccrueOffsetDriver)(double offset, double corr_rate);
+
+/* System driver to apply a step offset. A positive argument means step
+   the clock forwards. */
+typedef int (*lcl_ApplyStepOffsetDriver)(double offset);
+
+/* System driver to convert a raw time to an adjusted (cooked) time.
+   The number of seconds returned in 'corr' have to be added to the
+   raw time to get the corrected time */
+typedef void (*lcl_OffsetCorrectionDriver)(struct timespec *raw, double *corr, double *err);
+
+/* System driver to schedule leap seconds and set TAI-UTC offset */
+typedef void (*lcl_SetLeapDriver)(int leap, int tai_offset);
+
+/* System driver to set the synchronisation status */
+typedef void (*lcl_SetSyncStatusDriver)(int synchronised, double est_error, double max_error);
+
+extern void lcl_InvokeDispersionNotifyHandlers(double dispersion);
+
+extern void
+lcl_RegisterSystemDrivers(lcl_ReadFrequencyDriver read_freq,
+                          lcl_SetFrequencyDriver set_freq,
+                          lcl_AccrueOffsetDriver accrue_offset,
+                          lcl_ApplyStepOffsetDriver apply_step_offset,
+                          lcl_OffsetCorrectionDriver offset_convert,
+                          lcl_SetLeapDriver set_leap,
+                          lcl_SetSyncStatusDriver set_sync_status);
+
+#endif /* GOT_LOCALP_H */
diff --git a/logging.c b/logging.c
new file mode 100644
index 0000000..d858d2a
--- /dev/null
+++ b/logging.c
@@ -0,0 +1,352 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2014, 2018-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module to handle logging of diagnostic information
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <syslog.h>
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+
+/* This is used by DEBUG_LOG macro */
+LOG_Severity log_min_severity = LOGS_INFO;
+
+/* ================================================== */
+/* Flag indicating we have initialised */
+static int initialised = 0;
+
+static FILE *file_log = NULL;
+static int system_log = 0;
+
+static int parent_fd = 0;
+
+struct LogFile {
+  const char *name;
+  const char *banner;
+  FILE *file;
+  unsigned long writes;
+};
+
+static int n_filelogs = 0;
+
+/* Increase this when adding a new logfile */
+#define MAX_FILELOGS 6
+
+static struct LogFile logfiles[MAX_FILELOGS];
+
+/* Global prefix for debug messages */
+static char *debug_prefix;
+
+/* ================================================== */
+/* Init function */
+
+void
+LOG_Initialise(void)
+{
+  debug_prefix = Strdup("");
+  initialised = 1;
+  LOG_OpenFileLog(NULL);
+}
+
+/* ================================================== */
+/* Fini function */
+
+void
+LOG_Finalise(void)
+{
+  if (system_log)
+    closelog();
+
+  if (file_log)
+    fclose(file_log);
+
+  LOG_CycleLogFiles();
+
+  Free(debug_prefix);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+static void log_message(int fatal, LOG_Severity severity, const char *message)
+{
+  if (system_log) {
+    int priority;
+    switch (severity) {
+      case LOGS_DEBUG:
+        priority = LOG_DEBUG;
+        break;
+      case LOGS_INFO:
+        priority = LOG_INFO;
+        break;
+      case LOGS_WARN:
+        priority = LOG_WARNING;
+        break;
+      case LOGS_ERR:
+        priority = LOG_ERR;
+        break;
+      case LOGS_FATAL:
+        priority = LOG_CRIT;
+        break;
+      default:
+        assert(0);
+    }
+    syslog(priority, fatal ? "Fatal error : %s" : "%s", message);
+  } else if (file_log) {
+    fprintf(file_log, fatal ? "Fatal error : %s\n" : "%s\n", message);
+  }
+}
+
+/* ================================================== */
+
+void LOG_Message(LOG_Severity severity,
+#if DEBUG > 0
+                 int line_number, const char *filename, const char *function_name,
+#endif
+                 const char *format, ...)
+{
+  char buf[2048];
+  va_list other_args;
+  time_t t;
+  struct tm *tm;
+
+  assert(initialised);
+
+  if (!system_log && file_log && severity >= log_min_severity) {
+    /* Don't clutter up syslog with timestamps and internal debugging info */
+    time(&t);
+    tm = gmtime(&t);
+    if (tm) {
+      strftime(buf, sizeof (buf), "%Y-%m-%dT%H:%M:%SZ", tm);
+      fprintf(file_log, "%s ", buf);
+    }
+#if DEBUG > 0
+    if (log_min_severity <= LOGS_DEBUG)
+      fprintf(file_log, "%s%s:%d:(%s) ", debug_prefix, filename, line_number, function_name);
+#endif
+  }
+
+  va_start(other_args, format);
+  vsnprintf(buf, sizeof(buf), format, other_args);
+  va_end(other_args);
+
+  switch (severity) {
+    case LOGS_DEBUG:
+    case LOGS_INFO:
+    case LOGS_WARN:
+    case LOGS_ERR:
+      if (severity >= log_min_severity)
+        log_message(0, severity, buf);
+      break;
+    case LOGS_FATAL:
+      if (severity >= log_min_severity)
+        log_message(1, severity, buf);
+
+      /* Send the message also to the foreground process if it is
+         still running, or stderr if it is still open */
+      if (parent_fd > 0) {
+        if (write(parent_fd, buf, strlen(buf) + 1) < 0)
+          ; /* Not much we can do here */
+      } else if (system_log && parent_fd == 0) {
+        system_log = 0;
+        log_message(1, severity, buf);
+      }
+      exit(1);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+LOG_OpenFileLog(const char *log_file)
+{
+  FILE *f;
+
+  if (log_file) {
+    f = UTI_OpenFile(NULL, log_file, NULL, 'A', 0640);
+  } else {
+    f = stderr;
+  }
+
+  /* Enable line buffering */
+  setvbuf(f, NULL, _IOLBF, BUFSIZ);
+
+  if (file_log && file_log != stderr)
+    fclose(file_log);
+
+  file_log = f;
+}
+
+
+/* ================================================== */
+
+void
+LOG_OpenSystemLog(void)
+{
+  system_log = 1;
+  openlog("chronyd", LOG_PID, LOG_DAEMON);
+}
+
+/* ================================================== */
+
+void LOG_SetMinSeverity(LOG_Severity severity)
+{
+  /* Don't print any debug messages in a non-debug build */
+  log_min_severity = CLAMP(DEBUG > 0 ? LOGS_DEBUG : LOGS_INFO, severity, LOGS_FATAL);
+}
+
+/* ================================================== */
+
+LOG_Severity
+LOG_GetMinSeverity(void)
+{
+  return log_min_severity;
+}
+
+/* ================================================== */
+
+void
+LOG_SetDebugPrefix(const char *prefix)
+{
+  Free(debug_prefix);
+  debug_prefix = Strdup(prefix);
+}
+
+/* ================================================== */
+
+void
+LOG_SetParentFd(int fd)
+{
+  parent_fd = fd;
+  if (file_log == stderr)
+    file_log = NULL;
+}
+
+/* ================================================== */
+
+void
+LOG_CloseParentFd()
+{
+  if (parent_fd > 0)
+    close(parent_fd);
+  parent_fd = -1;
+}
+
+/* ================================================== */
+
+LOG_FileID
+LOG_FileOpen(const char *name, const char *banner)
+{
+  if (n_filelogs >= MAX_FILELOGS) {
+    assert(0);
+    return -1;
+  }
+
+  logfiles[n_filelogs].name = name;
+  logfiles[n_filelogs].banner = banner;
+  logfiles[n_filelogs].file = NULL;
+  logfiles[n_filelogs].writes = 0;
+
+  return n_filelogs++;
+}
+
+/* ================================================== */
+
+void
+LOG_FileWrite(LOG_FileID id, const char *format, ...)
+{
+  va_list other_args;
+  int banner;
+
+  if (id < 0 || id >= n_filelogs || !logfiles[id].name)
+    return;
+
+  if (!logfiles[id].file) {
+    char *logdir = CNF_GetLogDir();
+
+    if (!logdir) {
+      LOG(LOGS_WARN, "logdir not specified");
+      logfiles[id].name = NULL;
+      return;
+    }
+
+    logfiles[id].file = UTI_OpenFile(logdir, logfiles[id].name, ".log", 'a', 0644);
+    if (!logfiles[id].file) {
+      /* Disable the log */
+      logfiles[id].name = NULL;
+      return;
+    }
+  }
+
+  banner = CNF_GetLogBanner();
+  if (banner && logfiles[id].writes++ % banner == 0) {
+    char bannerline[256];
+    int i, bannerlen;
+
+    bannerlen = MIN(strlen(logfiles[id].banner), sizeof (bannerline) - 1);
+
+    for (i = 0; i < bannerlen; i++)
+      bannerline[i] = '=';
+    bannerline[i] = '\0';
+
+    fprintf(logfiles[id].file, "%s\n", bannerline);
+    fprintf(logfiles[id].file, "%s\n", logfiles[id].banner);
+    fprintf(logfiles[id].file, "%s\n", bannerline);
+  }
+
+  va_start(other_args, format);
+  vfprintf(logfiles[id].file, format, other_args);
+  va_end(other_args);
+  fprintf(logfiles[id].file, "\n");
+
+  fflush(logfiles[id].file);
+}
+
+/* ================================================== */
+
+void
+LOG_CycleLogFiles(void)
+{
+  LOG_FileID i;
+
+  for (i = 0; i < n_filelogs; i++) {
+    if (logfiles[i].file)
+      fclose(logfiles[i].file);
+    logfiles[i].file = NULL;
+    logfiles[i].writes = 0;
+  }
+}
+
+/* ================================================== */
diff --git a/logging.h b/logging.h
new file mode 100644
index 0000000..31bd462
--- /dev/null
+++ b/logging.h
@@ -0,0 +1,129 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2013-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for diagnostic logging module
+
+  */
+
+#ifndef GOT_LOGGING_H
+#define GOT_LOGGING_H
+
+#include "sysincl.h"
+
+/* Line logging macros.  If the compiler is GNU C, we take advantage of
+   being able to get the function name also. */
+
+#ifdef __GNUC__
+#define FUNCTION_NAME __FUNCTION__
+#define FORMAT_ATTRIBUTE_PRINTF(str, first) __attribute__ ((format (printf, str, first)))
+#else
+#define FUNCTION_NAME ""
+#define FORMAT_ATTRIBUTE_PRINTF(str, first)
+#endif
+
+#if DEBUG > 0
+#define LOG_MESSAGE(severity, ...) \
+  LOG_Message(severity, __LINE__, __FILE__, FUNCTION_NAME, __VA_ARGS__)
+#else
+#define LOG_MESSAGE(severity, ...) \
+  LOG_Message(severity, __VA_ARGS__)
+#endif
+
+#define DEBUG_LOG(...) \
+  do { \
+    if (DEBUG && log_min_severity == LOGS_DEBUG) \
+      LOG_MESSAGE(LOGS_DEBUG, __VA_ARGS__); \
+  } while (0)
+
+#define LOG_FATAL(...) \
+  do { \
+    LOG_MESSAGE(LOGS_FATAL, __VA_ARGS__); \
+    exit(1); \
+  } while (0)
+
+#define LOG(severity, ...) LOG_MESSAGE(severity, __VA_ARGS__)
+
+/* Definition of severity */
+typedef enum {
+  LOGS_DEBUG = -1,
+  LOGS_INFO = 0,
+  LOGS_WARN,
+  LOGS_ERR,
+  LOGS_FATAL,
+} LOG_Severity;
+
+/* Minimum severity of messages to be logged */
+extern LOG_Severity log_min_severity;
+
+/* Init function */
+extern void LOG_Initialise(void);
+
+/* Fini function */
+extern void LOG_Finalise(void);
+
+/* Line logging function */
+#if DEBUG > 0
+FORMAT_ATTRIBUTE_PRINTF(5, 6)
+extern void LOG_Message(LOG_Severity severity, int line_number, const char *filename,
+                        const char *function_name, const char *format, ...);
+#else
+FORMAT_ATTRIBUTE_PRINTF(2, 3)
+extern void LOG_Message(LOG_Severity severity, const char *format, ...);
+#endif
+
+/* Set the minimum severity of a message to be logged or printed to terminal.
+   If the severity is LOGS_DEBUG and DEBUG is enabled, all messages will be
+   prefixed with the filename, line number, and function name. */
+extern void LOG_SetMinSeverity(LOG_Severity severity);
+
+/* Get the minimum severity */
+extern LOG_Severity LOG_GetMinSeverity(void);
+
+/* Set a prefix for debug messages */
+extern void LOG_SetDebugPrefix(const char *prefix);
+
+/* Log messages to a file instead of stderr, or stderr again if NULL */
+extern void LOG_OpenFileLog(const char *log_file);
+
+/* Log messages to syslog instead of stderr */
+extern void LOG_OpenSystemLog(void);
+
+/* Stop using stderr and send fatal message to the foreground process */
+extern void LOG_SetParentFd(int fd);
+
+/* Close the pipe to the foreground process so it can exit */
+extern void LOG_CloseParentFd(void);
+
+/* File logging functions */
+
+typedef int LOG_FileID;
+
+extern LOG_FileID LOG_FileOpen(const char *name, const char *banner);
+
+FORMAT_ATTRIBUTE_PRINTF(2, 3)
+extern void LOG_FileWrite(LOG_FileID id, const char *format, ...);
+
+extern void LOG_CycleLogFiles(void);
+
+#endif /* GOT_LOGGING_H */
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..c40b5e4
--- /dev/null
+++ b/main.c
@@ -0,0 +1,694 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2012-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The main program
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "main.h"
+#include "sched.h"
+#include "local.h"
+#include "sys.h"
+#include "ntp_io.h"
+#include "ntp_signd.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "nts_ke_server.h"
+#include "nts_ntp_server.h"
+#include "socket.h"
+#include "sources.h"
+#include "sourcestats.h"
+#include "reference.h"
+#include "logging.h"
+#include "conf.h"
+#include "cmdmon.h"
+#include "keys.h"
+#include "manual.h"
+#include "rtc.h"
+#include "refclock.h"
+#include "clientlog.h"
+#include "nameserv.h"
+#include "privops.h"
+#include "smooth.h"
+#include "tempcomp.h"
+#include "util.h"
+
+/* ================================================== */
+
+/* Set when the initialisation chain has been completed.  Prevents finalisation
+ * chain being run if a fatal error happened early. */
+
+static int initialised = 0;
+
+static int exit_status = 0;
+
+static int reload = 0;
+
+static REF_Mode ref_mode = REF_ModeNormal;
+
+/* ================================================== */
+
+static void
+do_platform_checks(void)
+{
+  struct timespec ts;
+
+  /* Require at least 32-bit integers, two's complement representation and
+     the usual implementation of conversion of unsigned integers */
+  assert(sizeof (int) >= 4);
+  assert(-1 == ~0);
+  assert((int32_t)4294967295U == (int32_t)-1);
+
+  /* Require time_t and tv_nsec in timespec to be signed */
+  ts.tv_sec = -1;
+  ts.tv_nsec = -1;
+  assert(ts.tv_sec < 0 && ts.tv_nsec < 0);
+}
+
+/* ================================================== */
+
+static void
+delete_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+
+  if (!pidfile)
+    return;
+
+  if (!UTI_RemoveFile(NULL, pidfile, NULL))
+    ;
+}
+
+/* ================================================== */
+
+void
+MAI_CleanupAndExit(void)
+{
+  if (!initialised) exit(exit_status);
+  
+  LCL_CancelOffsetCorrection();
+  SRC_DumpSources();
+
+  /* Don't update clock when removing sources */
+  REF_SetMode(REF_ModeIgnore);
+
+  SMT_Finalise();
+  TMC_Finalise();
+  MNL_Finalise();
+  CLG_Finalise();
+  NKS_Finalise();
+  NNS_Finalise();
+  NSD_Finalise();
+  NSR_Finalise();
+  SST_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  CAM_Finalise();
+
+  KEY_Finalise();
+  RCL_Finalise();
+  SRC_Finalise();
+  REF_Finalise();
+  RTC_Finalise();
+  SYS_Finalise();
+
+  SCK_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+
+  delete_pidfile();
+  
+  CNF_Finalise();
+  HSH_Finalise();
+  LOG_Finalise();
+
+  UTI_ResetGetRandomFunctions();
+
+  exit(exit_status);
+}
+
+/* ================================================== */
+
+static void
+signal_cleanup(int x)
+{
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+quit_timeout(void *arg)
+{
+  LOG(LOGS_INFO, "Timeout reached");
+
+  /* Return with non-zero status if the clock is not synchronised */
+  exit_status = REF_GetOurStratum() >= NTP_MAX_STRATUM;
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+ntp_source_resolving_end(void)
+{
+  NSR_SetSourceResolvingEndHandler(NULL);
+
+  if (reload) {
+    /* Note, we want reload to come well after the initialisation from
+       the real time clock - this gives us a fighting chance that the
+       system-clock scale for the reloaded samples still has a
+       semblence of validity about it. */
+    SRC_ReloadSources();
+  }
+
+  SRC_RemoveDumpFiles();
+  RTC_StartMeasurements();
+  RCL_StartRefclocks();
+  NSR_StartSources();
+  NSR_AutoStartSources();
+
+  /* Special modes can end only when sources update their reachability.
+     Give up immediately if there are no active sources. */
+  if (ref_mode != REF_ModeNormal && !SRC_ActiveSources()) {
+    REF_SetUnsynchronised();
+  }
+}
+
+/* ================================================== */
+
+static void
+post_init_ntp_hook(void *anything)
+{
+  if (ref_mode == REF_ModeInitStepSlew) {
+    /* Remove the initstepslew sources and set normal mode */
+    NSR_RemoveAllSources();
+    ref_mode = REF_ModeNormal;
+    REF_SetMode(ref_mode);
+  }
+
+  /* Close the pipe to the foreground process so it can exit */
+  LOG_CloseParentFd();
+
+  CNF_AddSources();
+  CNF_AddBroadcasts();
+
+  NSR_SetSourceResolvingEndHandler(ntp_source_resolving_end);
+  NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+static void
+reference_mode_end(int result)
+{
+  switch (ref_mode) {
+    case REF_ModeNormal:
+    case REF_ModeUpdateOnce:
+    case REF_ModePrintOnce:
+      exit_status = !result;
+      SCH_QuitProgram();
+      break;
+    case REF_ModeInitStepSlew:
+      /* Switch to the normal mode, the delay is used to prevent polling
+         interval shorter than the burst interval if some configured servers
+         were used also for initstepslew */
+      SCH_AddTimeoutByDelay(2.0, post_init_ntp_hook, NULL);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+post_init_rtc_hook(void *anything)
+{
+  if (CNF_GetInitSources() > 0) {
+    CNF_AddInitSources();
+    NSR_StartSources();
+    assert(REF_GetMode() != REF_ModeNormal);
+    /* Wait for mode end notification */
+  } else {
+    (post_init_ntp_hook)(NULL);
+  }
+}
+
+/* ================================================== */
+
+static void
+check_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+  FILE *in;
+  int pid, count;
+  
+  if (!pidfile)
+    return;
+
+  in = UTI_OpenFile(NULL, pidfile, NULL, 'r', 0);
+  if (!in)
+    return;
+
+  count = fscanf(in, "%d", &pid);
+  fclose(in);
+  
+  if (count != 1)
+    return;
+
+  if (getsid(pid) < 0)
+    return;
+
+  LOG_FATAL("Another chronyd may already be running (pid=%d), check %s",
+            pid, pidfile);
+}
+
+/* ================================================== */
+
+static void
+write_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+  FILE *out;
+
+  if (!pidfile)
+    return;
+
+  out = UTI_OpenFile(NULL, pidfile, NULL, 'W', 0644);
+  fprintf(out, "%d\n", (int)getpid());
+  fclose(out);
+}
+
+/* ================================================== */
+
+#define DEV_NULL "/dev/null"
+
+static void
+go_daemon(void)
+{
+  int pid, fd, pipefd[2];
+
+  /* Create pipe which will the daemon use to notify the grandparent
+     when it's initialised or send an error message */
+  if (pipe(pipefd)) {
+    LOG_FATAL("pipe() failed : %s", strerror(errno));
+  }
+
+  /* Does this preserve existing signal handlers? */
+  pid = fork();
+
+  if (pid < 0) {
+    LOG_FATAL("fork() failed : %s", strerror(errno));
+  } else if (pid > 0) {
+    /* In the 'grandparent' */
+    char message[1024];
+    int r;
+
+    close(pipefd[1]);
+    r = read(pipefd[0], message, sizeof (message));
+    if (r) {
+      if (r > 0) {
+        /* Print the error message from the child */
+        message[sizeof (message) - 1] = '\0';
+        fprintf(stderr, "%s\n", message);
+      }
+      exit(1);
+    } else
+      exit(0);
+  } else {
+    close(pipefd[0]);
+
+    setsid();
+
+    /* Do 2nd fork, as-per recommended practice for launching daemons. */
+    pid = fork();
+
+    if (pid < 0) {
+      LOG_FATAL("fork() failed : %s", strerror(errno));
+    } else if (pid > 0) {
+      exit(0); /* In the 'parent' */
+    } else {
+      /* In the child we want to leave running as the daemon */
+
+      /* Change current directory to / */
+      if (chdir("/") < 0) {
+        LOG_FATAL("chdir() failed : %s", strerror(errno));
+      }
+
+      /* Don't keep stdin/out/err from before. But don't close
+         the parent pipe yet. */
+      for (fd=0; fd<1024; fd++) {
+        if (fd != pipefd[1])
+          close(fd);
+      }
+
+      LOG_SetParentFd(pipefd[1]);
+
+      /* Open /dev/null as new stdin/out/err */
+      errno = 0;
+      if (open(DEV_NULL, O_RDONLY) != STDIN_FILENO ||
+          open(DEV_NULL, O_WRONLY) != STDOUT_FILENO ||
+          open(DEV_NULL, O_RDWR) != STDERR_FILENO)
+        LOG_FATAL("Could not open %s : %s", DEV_NULL, strerror(errno));
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+print_help(const char *progname)
+{
+      printf("Usage: %s [OPTION]... [DIRECTIVE]...\n\n"
+             "Options:\n"
+             "  -4\t\tUse IPv4 addresses only\n"
+             "  -6\t\tUse IPv6 addresses only\n"
+             "  -f FILE\tSpecify configuration file (%s)\n"
+             "  -n\t\tDon't run as daemon\n"
+             "  -d\t\tDon't run as daemon and log to stderr\n"
+#if DEBUG > 0
+             "  -d -d\t\tEnable debug messages\n"
+#endif
+             "  -l FILE\tLog to file\n"
+             "  -L LEVEL\tSet logging threshold (0)\n"
+             "  -p\t\tPrint configuration and exit\n"
+             "  -q\t\tSet clock and exit\n"
+             "  -Q\t\tLog offset and exit\n"
+             "  -r\t\tReload dump files\n"
+             "  -R\t\tAdapt configuration for restart\n"
+             "  -s\t\tSet clock from RTC\n"
+             "  -t SECONDS\tExit after elapsed time\n"
+             "  -u USER\tSpecify user (%s)\n"
+             "  -U\t\tDon't check for root\n"
+             "  -F LEVEL\tSet system call filter level (0)\n"
+             "  -P PRIORITY\tSet process priority (0)\n"
+             "  -m\t\tLock memory\n"
+             "  -x\t\tDon't control clock\n"
+             "  -v, --version\tPrint version and exit\n"
+             "  -h, --help\tPrint usage and exit\n",
+             progname, DEFAULT_CONF_FILE, DEFAULT_USER);
+}
+
+/* ================================================== */
+
+static void
+print_version(void)
+{
+  printf("chronyd (chrony) version %s (%s)\n", CHRONY_VERSION, CHRONYD_FEATURES);
+}
+
+/* ================================================== */
+
+static int
+parse_int_arg(const char *arg)
+{
+  int i;
+
+  if (sscanf(arg, "%d", &i) != 1)
+    LOG_FATAL("Invalid argument %s", arg);
+  return i;
+}
+
+/* ================================================== */
+
+int main
+(int argc, char **argv)
+{
+  const char *conf_file = DEFAULT_CONF_FILE;
+  const char *progname = argv[0];
+  char *user = NULL, *log_file = NULL;
+  struct passwd *pw;
+  int opt, debug = 0, nofork = 0, address_family = IPADDR_UNSPEC;
+  int do_init_rtc = 0, restarted = 0, client_only = 0, timeout = -1;
+  int scfilter_level = 0, lock_memory = 0, sched_priority = 0;
+  int clock_control = 1, system_log = 1, log_severity = LOGS_INFO;
+  int user_check = 1, config_args = 0, print_config = 0;
+
+  do_platform_checks();
+
+  LOG_Initialise();
+
+  /* Parse long command-line options */
+  for (optind = 1; optind < argc; optind++) {
+    if (!strcmp("--help", argv[optind])) {
+      print_help(progname);
+      return 0;
+    } else if (!strcmp("--version", argv[optind])) {
+      print_version();
+      return 0;
+    }
+  }
+
+  optind = 1;
+
+  /* Parse short command-line options */
+  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnpP:qQrRst:u:Uvx")) != -1) {
+    switch (opt) {
+      case '4':
+      case '6':
+        address_family = opt == '4' ? IPADDR_INET4 : IPADDR_INET6;
+        break;
+      case 'd':
+        debug++;
+        nofork = 1;
+        system_log = 0;
+        break;
+      case 'f':
+        conf_file = optarg;
+        break;
+      case 'F':
+        scfilter_level = parse_int_arg(optarg);
+        break;
+      case 'l':
+        log_file = optarg;
+        break;
+      case 'L':
+        log_severity = parse_int_arg(optarg);
+        break;
+      case 'm':
+        lock_memory = 1;
+        break;
+      case 'n':
+        nofork = 1;
+        break;
+      case 'p':
+        print_config = 1;
+        user_check = 0;
+        nofork = 1;
+        system_log = 0;
+        log_severity = LOGS_WARN;
+        break;
+      case 'P':
+        sched_priority = parse_int_arg(optarg);
+        break;
+      case 'q':
+        ref_mode = REF_ModeUpdateOnce;
+        nofork = 1;
+        client_only = 0;
+        system_log = 0;
+        break;
+      case 'Q':
+        ref_mode = REF_ModePrintOnce;
+        nofork = 1;
+        client_only = 1;
+        user_check = 0;
+        clock_control = 0;
+        system_log = 0;
+        break;
+      case 'r':
+        reload = 1;
+        break;
+      case 'R':
+        restarted = 1;
+        break;
+      case 's':
+        do_init_rtc = 1;
+        break;
+      case 't':
+        timeout = parse_int_arg(optarg);
+        break;
+      case 'u':
+        user = optarg;
+        break;
+      case 'U':
+        user_check = 0;
+        break;
+      case 'v':
+        print_version();
+        return 0;
+      case 'x':
+        clock_control = 0;
+        break;
+      default:
+        print_help(progname);
+        return opt != 'h';
+    }
+  }
+
+  if (user_check && getuid() != 0)
+    LOG_FATAL("Not superuser");
+
+  /* Turn into a daemon */
+  if (!nofork) {
+    go_daemon();
+  }
+
+  if (log_file) {
+    LOG_OpenFileLog(log_file);
+  } else if (system_log) {
+    LOG_OpenSystemLog();
+  }
+  
+  LOG_SetMinSeverity(debug >= 2 ? LOGS_DEBUG : log_severity);
+  
+  LOG(LOGS_INFO, "chronyd version %s starting (%s)", CHRONY_VERSION, CHRONYD_FEATURES);
+
+  DNS_SetAddressFamily(address_family);
+
+  CNF_Initialise(restarted, client_only);
+  if (print_config)
+    CNF_EnablePrint();
+
+  /* Parse the config file or the remaining command line arguments */
+  config_args = argc - optind;
+  if (!config_args) {
+    CNF_ReadFile(conf_file);
+  } else {
+    for (; optind < argc; optind++)
+      CNF_ParseLine(NULL, config_args + optind - argc + 1, argv[optind]);
+  }
+
+  if (print_config)
+    return 0;
+
+  /* Check whether another chronyd may already be running */
+  check_pidfile();
+
+  if (!user)
+    user = CNF_GetUser();
+
+  pw = getpwnam(user);
+  if (!pw)
+    LOG_FATAL("Could not get user/group ID of %s", user);
+
+  /* Create directories for sockets, log files, and dump files */
+  CNF_CreateDirs(pw->pw_uid, pw->pw_gid);
+
+  /* Write our pidfile to prevent other instances from running */
+  write_pidfile();
+
+  PRV_Initialise();
+  LCL_Initialise();
+  SCH_Initialise();
+  SCK_Initialise(address_family);
+
+  /* Start helper processes if needed */
+  NKS_PreInitialise(pw->pw_uid, pw->pw_gid, scfilter_level);
+
+  SYS_Initialise(clock_control);
+  RTC_Initialise(do_init_rtc);
+  SRC_Initialise();
+  RCL_Initialise();
+  KEY_Initialise();
+
+  /* Open privileged ports before dropping root */
+  CAM_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  CNF_SetupAccessRestrictions();
+
+  /* Command-line switch must have priority */
+  if (!sched_priority) {
+    sched_priority = CNF_GetSchedPriority();
+  }
+  if (sched_priority) {
+    SYS_SetScheduler(sched_priority);
+  }
+
+  if (lock_memory || CNF_GetLockMemory()) {
+    SYS_LockMemory();
+  }
+
+  /* Drop root privileges if the specified user has a non-zero UID */
+  if (!geteuid() && (pw->pw_uid || pw->pw_gid))
+    SYS_DropRoot(pw->pw_uid, pw->pw_gid, SYS_MAIN_PROCESS);
+
+  if (!geteuid())
+    LOG(LOGS_WARN, "Running with root privileges");
+
+  REF_Initialise();
+  SST_Initialise();
+  NSR_Initialise();
+  NSD_Initialise();
+  NNS_Initialise();
+  NKS_Initialise();
+  CLG_Initialise();
+  MNL_Initialise();
+  TMC_Initialise();
+  SMT_Initialise();
+
+  /* From now on, it is safe to do finalisation on exit */
+  initialised = 1;
+
+  UTI_SetQuitSignalsHandler(signal_cleanup, 1);
+
+  CAM_OpenUnixSocket();
+
+  if (scfilter_level)
+    SYS_EnableSystemCallFilter(scfilter_level, SYS_MAIN_PROCESS);
+
+  if (ref_mode == REF_ModeNormal && CNF_GetInitSources() > 0) {
+    ref_mode = REF_ModeInitStepSlew;
+  }
+
+  REF_SetModeEndHandler(reference_mode_end);
+  REF_SetMode(ref_mode);
+
+  if (timeout >= 0)
+    SCH_AddTimeoutByDelay(timeout, quit_timeout, NULL);
+
+  if (do_init_rtc) {
+    RTC_TimeInit(post_init_rtc_hook, NULL);
+  } else {
+    post_init_rtc_hook(NULL);
+  }
+
+  /* The program normally runs under control of the main loop in
+     the scheduler. */
+  SCH_MainLoop();
+
+  LOG(LOGS_INFO, "chronyd exiting");
+
+  MAI_CleanupAndExit();
+
+  return 0;
+}
+
+/* ================================================== */
diff --git a/main.h b/main.h
new file mode 100644
index 0000000..d6d502a
--- /dev/null
+++ b/main.h
@@ -0,0 +1,35 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for main routine
+  */
+
+#ifndef GOT_MAIN_H
+#define GOT_MAIN_H
+
+/* Function to clean up at end of run */
+extern void MAI_CleanupAndExit(void);
+
+#endif /* GOT_MAIN_H */
+
+
diff --git a/manual.c b/manual.c
new file mode 100644
index 0000000..98a3aa2
--- /dev/null
+++ b/manual.c
@@ -0,0 +1,332 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines for implementing manual input of real time.
+
+  The daemon accepts manual time input over the control connection,
+  and adjusts the system time to match.  Besides this, though, it can
+  determine the average rate of time loss or gain of the local system
+  and adjust the frequency accordingly.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "manual.h"
+#include "logging.h"
+#include "local.h"
+#include "conf.h"
+#include "util.h"
+#include "ntp.h"
+#include "reference.h"
+#include "regress.h"
+
+static int enabled = 0;
+
+/* More recent samples at highest indices */
+typedef struct {
+  struct timespec when; /* This is our 'cooked' time */
+  double orig_offset; /*+ Not modified by slew samples */
+  double offset; /*+ if we are fast of the supplied reference */
+  double residual; /*+ regression residual (sign convention given by
+                     (measured-predicted)) */
+} Sample;
+
+#define MIN_SAMPLE_SEPARATION 1.0
+
+#define MAX_SAMPLES 16
+
+static Sample samples[16];
+static int n_samples;
+
+/* ================================================== */
+
+static void
+slew_samples(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *not_used);
+
+/* ================================================== */
+
+void
+MNL_Initialise(void)
+{
+  if (CNF_GetManualEnabled()) {
+    enabled = 1;
+  } else {
+    enabled = 0;
+  }
+
+  n_samples = 0;
+
+  LCL_AddParameterChangeHandler(slew_samples, NULL);
+}
+
+/* ================================================== */
+
+void
+MNL_Finalise(void)
+{
+  LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+}
+
+/* ================================================== */
+
+static void
+estimate_and_set_system(struct timespec *now, int offset_provided, double offset,
+                        double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm)
+{
+  double agos[MAX_SAMPLES], offsets[MAX_SAMPLES];
+  double b0, b1;
+  int n_runs, best_start; /* Unused results from regression analyser */
+  int i;
+  double freq = 0.0;
+  double skew = 0.099999999; /* All 9's when printed to log file */
+  int found_freq;
+  double slew_by;
+
+  b0 = offset_provided ? offset : 0.0;
+  b1 = freq = 0.0;
+  found_freq = 0;
+
+  if (n_samples > 1) {
+    for (i=0; i<n_samples; i++) {
+      agos[i] = UTI_DiffTimespecsToDouble(&samples[n_samples - 1].when, &samples[i].when);
+      offsets[i] = samples[i].offset;
+    }
+    
+    if (RGR_FindBestRobustRegression(agos, offsets, n_samples, 1.0e-8,
+                                     &b0, &b1, &n_runs, &best_start)) {
+      /* Ignore b0 from regression; treat offset as being the most
+         recently entered value.  (If the administrator knows he's put
+         an outlier in, he will rerun the settime operation.)   However,
+         the frequency estimate comes from the regression. */
+      freq = -b1;
+      found_freq = 1;
+    }
+  } else {
+    agos[0] = 0.0;
+    offsets[0] = b0;
+  }
+
+  if (offset_provided) {
+    slew_by = offset;
+  } else {
+    slew_by = b0;
+  }
+  
+  if (found_freq) {
+    LOG(LOGS_INFO, "Making a frequency change of %.3f ppm and a slew of %.6f",
+        1.0e6 * freq, slew_by);
+    
+    REF_SetManualReference(now,
+                           slew_by,
+                           freq, skew);
+  } else {
+    LOG(LOGS_INFO, "Making a slew of %.6f", slew_by);
+    REF_SetManualReference(now,
+                           slew_by,
+                           0.0, skew);
+  }
+  
+  if (reg_offset) *reg_offset = b0;
+  if (dfreq_ppm) *dfreq_ppm = 1.0e6 * freq;
+  if (new_afreq_ppm) *new_afreq_ppm = LCL_ReadAbsoluteFrequency();
+  
+  /* Calculate residuals to store them */
+  for (i=0; i<n_samples; i++) {
+    samples[i].residual = offsets[i] - (b0 + agos[i] * b1);
+  }
+  
+}
+
+/* ================================================== */
+
+int
+MNL_AcceptTimestamp(struct timespec *ts, double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm)
+{
+  struct timespec now;
+  double offset, diff;
+  int i;
+
+  if (enabled) {
+    LCL_ReadCookedTime(&now, NULL);
+
+    /* Make sure the provided timestamp is sane and the sample
+       is not too close to the last one */
+
+    if (!UTI_IsTimeOffsetSane(ts, 0.0))
+     return 0;
+
+    if (n_samples) {
+      diff = UTI_DiffTimespecsToDouble(&now, &samples[n_samples - 1].when);
+      if (diff < MIN_SAMPLE_SEPARATION)
+        return 0;
+    }
+
+    offset = UTI_DiffTimespecsToDouble(&now, ts);
+
+    /* Check if buffer full up */
+    if (n_samples == MAX_SAMPLES) {
+      /* Shift samples down */
+      for (i=1; i<n_samples; i++) {
+        samples[i-1] = samples[i];
+      }
+      --n_samples;
+    }
+    
+    samples[n_samples].when = now;
+    samples[n_samples].offset = offset;
+    samples[n_samples].orig_offset = offset;
+    ++n_samples;
+
+    estimate_and_set_system(&now, 1, offset, reg_offset, dfreq_ppm, new_afreq_ppm);
+
+    return 1;
+
+  } else {
+  
+    return 0;
+
+  }
+}
+
+/* ================================================== */
+
+static void
+slew_samples(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *not_used)
+{
+  double delta_time;
+  int i;
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    MNL_Reset();
+  }
+
+  for (i=0; i<n_samples; i++) {
+    UTI_AdjustTimespec(&samples[i].when, cooked, &samples[i].when, &delta_time,
+        dfreq, doffset);
+    samples[i].offset += delta_time;
+  }
+}
+
+/* ================================================== */
+
+void
+MNL_Enable(void)
+{
+  enabled = 1;
+}
+
+
+/* ================================================== */
+
+void
+MNL_Disable(void)
+{
+  enabled = 0;
+}
+
+/* ================================================== */
+
+void
+MNL_Reset(void)
+{
+  n_samples = 0;
+}
+
+/* ================================================== */
+
+int
+MNL_IsEnabled(void)
+{
+  return enabled;
+}
+
+/* ================================================== */
+/* Generate report data for the REQ_MANUAL_LIST command/monitoring
+   protocol */
+
+void
+MNL_ReportSamples(RPT_ManualSamplesReport *report, int max, int *n)
+{
+  int i;
+
+  if (n_samples > max) {
+    *n = max;
+  } else {
+    *n = n_samples;
+  }
+
+  for (i=0; i<n_samples && i<max; i++) {
+    report[i].when = samples[i].when;
+    report[i].slewed_offset = samples[i].offset;
+    report[i].orig_offset = samples[i].orig_offset;
+    report[i].residual = samples[i].residual;
+  }
+}
+
+/* ================================================== */
+/* Delete a sample if it's within range, re-estimate the error and
+   drift and apply it to the system clock. */
+
+int
+MNL_DeleteSample(int index)
+{
+  int i;
+  struct timespec now;
+
+  if ((index < 0) || (index >= n_samples)) {
+    return 0;
+  }
+
+  /* Crunch the samples down onto the one being deleted */
+
+  for (i=index; i<(n_samples-1); i++) {
+    samples[i] = samples[i+1];
+  }
+  
+  n_samples -= 1;
+
+  /* Now re-estimate.  NULLs because we don't want the parameters back
+     in this case. */
+  LCL_ReadCookedTime(&now, NULL);
+  estimate_and_set_system(&now, 0, 0.0, NULL, NULL, NULL);
+
+  return 1;
+
+}
+
+/* ================================================== */
+
+
diff --git a/manual.h b/manual.h
new file mode 100644
index 0000000..7f3d0b2
--- /dev/null
+++ b/manual.h
@@ -0,0 +1,46 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for manual time input module.
+
+  */
+
+#ifndef GOT_MANUAL_H
+#define GOT_MANUAL_H
+
+#include "sysincl.h"
+#include "reports.h"
+
+extern void MNL_Initialise(void);
+extern void MNL_Finalise(void);
+extern int MNL_AcceptTimestamp(struct timespec *ts, double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm);
+
+extern void MNL_Enable(void);
+extern void MNL_Disable(void);
+extern void MNL_Reset(void);
+extern int MNL_IsEnabled(void);
+
+extern void MNL_ReportSamples(RPT_ManualSamplesReport *report, int max, int *n);
+extern int MNL_DeleteSample(int index);
+
+#endif /* GOT_MANUAL_H */
diff --git a/md5.c b/md5.c
new file mode 100644
index 0000000..f997a6e
--- /dev/null
+++ b/md5.c
@@ -0,0 +1,322 @@
+/*
+ ***********************************************************************
+ ** md5.c -- the source code for MD5 routines                         **
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 1/91 SRD,AJ,BSK,JT Reference C Version                   **
+ ** Revised (for MD5): RLR 4/27/91                                    **
+ **   -- G modified to have y&~z instead of y&z                       **
+ **   -- FF, GG, HH modified to add in last register done             **
+ **   -- Access pattern: round 2 works mod 5, round 3 works mod 3     **
+ **   -- distinct additive constant for each step                     **
+ **   -- round 4 added, working mod 7                                 **
+ ***********************************************************************
+ */
+
+/*
+ ***********************************************************************
+ ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
+ **                                                                   **
+ ** License to copy and use this software is granted provided that    **
+ ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
+ ** Digest Algorithm" in all material mentioning or referencing this  **
+ ** software or this function.                                        **
+ **                                                                   **
+ ** License is also granted to make and use derivative works          **
+ ** provided that such works are identified as "derived from the RSA  **
+ ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
+ ** material mentioning or referencing the derived work.              **
+ **                                                                   **
+ ** RSA Data Security, Inc. makes no representations concerning       **
+ ** either the merchantability of this software or the suitability    **
+ ** of this software for any particular purpose.  It is provided "as  **
+ ** is" without express or implied warranty of any kind.              **
+ **                                                                   **
+ ** These notices must be retained in any copies of any part of this  **
+ ** documentation and/or software.                                    **
+ ***********************************************************************
+ */
+
+#include "md5.h"
+
+/*
+ ***********************************************************************
+ **  Message-digest routines:                                         **
+ **  To form the message digest for a message M                       **
+ **    (1) Initialize a context buffer mdContext using MD5Init        **
+ **    (2) Call MD5Update on mdContext and M                          **
+ **    (3) Call MD5Final on mdContext                                 **
+ **  The message digest is now in mdContext->digest[0...15]           **
+ ***********************************************************************
+ */
+
+/* forward declaration */
+static void Transform (UINT4 *, UINT4 *);
+
+#ifdef	__STDC__
+static const
+#else
+static
+#endif
+unsigned char PADDING[64] = {
+  0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+/* F, G, H and I are basic MD5 functions */
+#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
+#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+#define I(x, y, z) ((y) ^ ((x) | (~z)))
+
+/* ROTATE_LEFT rotates x left n bits */
+#if	defined(FAST_MD5) && defined(__GNUC__) && defined(mc68000)
+/*
+ * If we're on a 68000 based CPU and using a GNU C compiler with
+ * inline assembly code, we can speed this up a bit.
+ */
+inline UINT4 ROTATE_LEFT(UINT4 x, int n)
+{   
+    asm("roll %2,%0" : "=d" (x) : "0" (x), "Ir" (n));
+    return x;
+}
+#else
+#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
+#endif
+
+
+/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
+/* Rotation is separate from addition to prevent recomputation */
+#define FF(a, b, c, d, x, s, ac) \
+  {(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define GG(a, b, c, d, x, s, ac) \
+  {(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define HH(a, b, c, d, x, s, ac) \
+  {(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define II(a, b, c, d, x, s, ac) \
+  {(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+
+/* The routine MD5Init initializes the message-digest context
+   mdContext. All fields are set to zero.
+ */
+void MD5Init (mdContext)
+MD5_CTX *mdContext;
+{
+  mdContext->i[0] = mdContext->i[1] = (UINT4)0;
+
+  /* Load magic initialization constants.
+   */
+  mdContext->buf[0] = (UINT4)0x67452301;
+  mdContext->buf[1] = (UINT4)0xefcdab89;
+  mdContext->buf[2] = (UINT4)0x98badcfe;
+  mdContext->buf[3] = (UINT4)0x10325476;
+}
+
+/* The routine MD5Update updates the message-digest context to
+   account for the presence of each of the characters inBuf[0..inLen-1]
+   in the message whose digest is being computed.
+ */
+void MD5Update (mdContext, inBuf, inLen)
+MD5_CTX *mdContext;
+unsigned const char *inBuf;
+unsigned int inLen;
+{
+  UINT4 in[16];
+  int mdi;
+  unsigned int i, ii;
+
+  /* compute number of bytes mod 64 */
+  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);
+
+  /* update number of bits */
+  if ((mdContext->i[0] + ((UINT4)inLen << 3)) < mdContext->i[0])
+    mdContext->i[1]++;
+  mdContext->i[0] += ((UINT4)inLen << 3);
+  mdContext->i[1] += ((UINT4)inLen >> 29);
+
+  while (inLen--) {
+    /* add new character to buffer, increment mdi */
+    mdContext->in[mdi++] = *inBuf++;
+
+    /* transform if necessary */
+    if (mdi == 0x40) {
+      for (i = 0, ii = 0; i < 16; i++, ii += 4)
+        in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
+                (((UINT4)mdContext->in[ii+2]) << 16) |
+                (((UINT4)mdContext->in[ii+1]) << 8) |
+                ((UINT4)mdContext->in[ii]);
+      Transform (mdContext->buf, in);
+      mdi = 0;
+    }
+  }
+}
+
+/* The routine MD5Final terminates the message-digest computation and
+   ends with the desired message digest in mdContext->digest[0...15].
+ */
+
+void MD5Final (mdContext)
+MD5_CTX *mdContext;
+{
+  UINT4 in[16];
+  int mdi;
+  unsigned int i, ii;
+  unsigned int padLen;
+
+  /* save number of bits */
+  in[14] = mdContext->i[0];
+  in[15] = mdContext->i[1];
+
+  /* compute number of bytes mod 64 */
+  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);
+
+  /* pad out to 56 mod 64 */
+  padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
+  MD5Update (mdContext, PADDING, padLen);
+
+  /* append length in bits and transform */
+  for (i = 0, ii = 0; i < 14; i++, ii += 4)
+    in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
+            (((UINT4)mdContext->in[ii+2]) << 16) |
+            (((UINT4)mdContext->in[ii+1]) << 8) |
+            ((UINT4)mdContext->in[ii]);
+  Transform (mdContext->buf, in);
+
+  /* store buffer in digest */
+  for (i = 0, ii = 0; i < 4; i++, ii += 4) {
+    mdContext->digest[ii] = (unsigned char)(mdContext->buf[i] & 0xFF);
+    mdContext->digest[ii+1] =
+      (unsigned char)((mdContext->buf[i] >> 8) & 0xFF);
+    mdContext->digest[ii+2] =
+      (unsigned char)((mdContext->buf[i] >> 16) & 0xFF);
+    mdContext->digest[ii+3] =
+      (unsigned char)((mdContext->buf[i] >> 24) & 0xFF);
+  }
+}
+
+/* Basic MD5 step. Transforms buf based on in.
+ */
+static void Transform (buf, in)
+UINT4 *buf;
+UINT4 *in;
+{
+  UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
+
+  /* Round 1 */
+#define S11 7
+#define S12 12
+#define S13 17
+#define S14 22
+
+  FF ( a, b, c, d, in[ 0], S11, 0xd76aa478); /* 1 */
+  FF ( d, a, b, c, in[ 1], S12, 0xe8c7b756); /* 2 */
+  FF ( c, d, a, b, in[ 2], S13, 0x242070db); /* 3 */
+  FF ( b, c, d, a, in[ 3], S14, 0xc1bdceee); /* 4 */
+  FF ( a, b, c, d, in[ 4], S11, 0xf57c0faf); /* 5 */
+  FF ( d, a, b, c, in[ 5], S12, 0x4787c62a); /* 6 */
+  FF ( c, d, a, b, in[ 6], S13, 0xa8304613); /* 7 */
+  FF ( b, c, d, a, in[ 7], S14, 0xfd469501); /* 8 */
+  FF ( a, b, c, d, in[ 8], S11, 0x698098d8); /* 9 */
+  FF ( d, a, b, c, in[ 9], S12, 0x8b44f7af); /* 10 */
+  FF ( c, d, a, b, in[10], S13, 0xffff5bb1); /* 11 */
+  FF ( b, c, d, a, in[11], S14, 0x895cd7be); /* 12 */
+  FF ( a, b, c, d, in[12], S11, 0x6b901122); /* 13 */
+  FF ( d, a, b, c, in[13], S12, 0xfd987193); /* 14 */
+  FF ( c, d, a, b, in[14], S13, 0xa679438e); /* 15 */
+  FF ( b, c, d, a, in[15], S14, 0x49b40821); /* 16 */
+
+  /* Round 2 */
+#define S21 5
+#define S22 9
+#define S23 14
+#define S24 20
+  GG ( a, b, c, d, in[ 1], S21, 0xf61e2562); /* 17 */
+  GG ( d, a, b, c, in[ 6], S22, 0xc040b340); /* 18 */
+  GG ( c, d, a, b, in[11], S23, 0x265e5a51); /* 19 */
+  GG ( b, c, d, a, in[ 0], S24, 0xe9b6c7aa); /* 20 */
+  GG ( a, b, c, d, in[ 5], S21, 0xd62f105d); /* 21 */
+  GG ( d, a, b, c, in[10], S22,  0x2441453); /* 22 */
+  GG ( c, d, a, b, in[15], S23, 0xd8a1e681); /* 23 */
+  GG ( b, c, d, a, in[ 4], S24, 0xe7d3fbc8); /* 24 */
+  GG ( a, b, c, d, in[ 9], S21, 0x21e1cde6); /* 25 */
+  GG ( d, a, b, c, in[14], S22, 0xc33707d6); /* 26 */
+  GG ( c, d, a, b, in[ 3], S23, 0xf4d50d87); /* 27 */
+  GG ( b, c, d, a, in[ 8], S24, 0x455a14ed); /* 28 */
+  GG ( a, b, c, d, in[13], S21, 0xa9e3e905); /* 29 */
+  GG ( d, a, b, c, in[ 2], S22, 0xfcefa3f8); /* 30 */
+  GG ( c, d, a, b, in[ 7], S23, 0x676f02d9); /* 31 */
+  GG ( b, c, d, a, in[12], S24, 0x8d2a4c8a); /* 32 */
+
+  /* Round 3 */
+#define S31 4
+#define S32 11
+#define S33 16
+#define S34 23
+  HH ( a, b, c, d, in[ 5], S31, 0xfffa3942); /* 33 */
+  HH ( d, a, b, c, in[ 8], S32, 0x8771f681); /* 34 */
+  HH ( c, d, a, b, in[11], S33, 0x6d9d6122); /* 35 */
+  HH ( b, c, d, a, in[14], S34, 0xfde5380c); /* 36 */
+  HH ( a, b, c, d, in[ 1], S31, 0xa4beea44); /* 37 */
+  HH ( d, a, b, c, in[ 4], S32, 0x4bdecfa9); /* 38 */
+  HH ( c, d, a, b, in[ 7], S33, 0xf6bb4b60); /* 39 */
+  HH ( b, c, d, a, in[10], S34, 0xbebfbc70); /* 40 */
+  HH ( a, b, c, d, in[13], S31, 0x289b7ec6); /* 41 */
+  HH ( d, a, b, c, in[ 0], S32, 0xeaa127fa); /* 42 */
+  HH ( c, d, a, b, in[ 3], S33, 0xd4ef3085); /* 43 */
+  HH ( b, c, d, a, in[ 6], S34,  0x4881d05); /* 44 */
+  HH ( a, b, c, d, in[ 9], S31, 0xd9d4d039); /* 45 */
+  HH ( d, a, b, c, in[12], S32, 0xe6db99e5); /* 46 */
+  HH ( c, d, a, b, in[15], S33, 0x1fa27cf8); /* 47 */
+  HH ( b, c, d, a, in[ 2], S34, 0xc4ac5665); /* 48 */
+
+  /* Round 4 */
+#define S41 6
+#define S42 10
+#define S43 15
+#define S44 21
+  II ( a, b, c, d, in[ 0], S41, 0xf4292244); /* 49 */
+  II ( d, a, b, c, in[ 7], S42, 0x432aff97); /* 50 */
+  II ( c, d, a, b, in[14], S43, 0xab9423a7); /* 51 */
+  II ( b, c, d, a, in[ 5], S44, 0xfc93a039); /* 52 */
+  II ( a, b, c, d, in[12], S41, 0x655b59c3); /* 53 */
+  II ( d, a, b, c, in[ 3], S42, 0x8f0ccc92); /* 54 */
+  II ( c, d, a, b, in[10], S43, 0xffeff47d); /* 55 */
+  II ( b, c, d, a, in[ 1], S44, 0x85845dd1); /* 56 */
+  II ( a, b, c, d, in[ 8], S41, 0x6fa87e4f); /* 57 */
+  II ( d, a, b, c, in[15], S42, 0xfe2ce6e0); /* 58 */
+  II ( c, d, a, b, in[ 6], S43, 0xa3014314); /* 59 */
+  II ( b, c, d, a, in[13], S44, 0x4e0811a1); /* 60 */
+  II ( a, b, c, d, in[ 4], S41, 0xf7537e82); /* 61 */
+  II ( d, a, b, c, in[11], S42, 0xbd3af235); /* 62 */
+  II ( c, d, a, b, in[ 2], S43, 0x2ad7d2bb); /* 63 */
+  II ( b, c, d, a, in[ 9], S44, 0xeb86d391); /* 64 */
+
+  buf[0] += a;
+  buf[1] += b;
+  buf[2] += c;
+  buf[3] += d;
+}
+
+/*
+ ***********************************************************************
+ ** End of md5.c                                                      **
+ ******************************** (cut) ********************************
+ */
diff --git a/md5.h b/md5.h
new file mode 100644
index 0000000..5f37235
--- /dev/null
+++ b/md5.h
@@ -0,0 +1,56 @@
+/*
+ ***********************************************************************
+ ** md5.h -- header file for implementation of MD5                    **
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 12/27/90 SRD,AJ,BSK,JT Reference C version               **
+ ** Revised (for MD5): RLR 4/27/91                                    **
+ ***********************************************************************
+ */
+
+/*
+ ***********************************************************************
+ ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
+ **                                                                   **
+ ** License to copy and use this software is granted provided that    **
+ ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
+ ** Digest Algorithm" in all material mentioning or referencing this  **
+ ** software or this function.                                        **
+ **                                                                   **
+ ** License is also granted to make and use derivative works          **
+ ** provided that such works are identified as "derived from the RSA  **
+ ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
+ ** material mentioning or referencing the derived work.              **
+ **                                                                   **
+ ** RSA Data Security, Inc. makes no representations concerning       **
+ ** either the merchantability of this software or the suitability    **
+ ** of this software for any particular purpose.  It is provided "as  **
+ ** is" without express or implied warranty of any kind.              **
+ **                                                                   **
+ ** These notices must be retained in any copies of any part of this  **
+ ** documentation and/or software.                                    **
+ ***********************************************************************
+ */
+
+#include "sysincl.h"
+
+/* typedef a 32-bit type */
+typedef uint32_t UINT4;
+
+/* Data structure for MD5 (Message-Digest) computation */
+typedef struct {
+  UINT4 i[2];                   /* number of _bits_ handled mod 2^64 */
+  UINT4 buf[4];                                    /* scratch buffer */
+  unsigned char in[64];                              /* input buffer */
+  unsigned char digest[16];     /* actual digest after MD5Final call */
+} MD5_CTX;
+
+void MD5Init (MD5_CTX *mdContext);
+void MD5Update (MD5_CTX *, unsigned const char *, unsigned int);
+void MD5Final (MD5_CTX *);
+
+/*
+ ***********************************************************************
+ ** End of md5.h                                                      **
+ ******************************** (cut) ********************************
+ */
diff --git a/memory.c b/memory.c
new file mode 100644
index 0000000..03366e5
--- /dev/null
+++ b/memory.c
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014, 2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Utility functions for memory allocation.
+
+  */
+
+#include "config.h"
+
+#include "logging.h"
+#include "memory.h"
+
+void *
+Malloc(size_t size)
+{
+  void *r;
+
+  r = malloc(size);
+  if (!r && size)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
+
+void *
+Realloc(void *ptr, size_t size)
+{
+  void *r;
+
+  r = realloc(ptr, size);
+  if (!r && size)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
+
+static size_t
+get_array_size(size_t nmemb, size_t size)
+{
+  size_t array_size;
+
+  array_size = nmemb * size;
+
+  /* Check for overflow */
+  if (nmemb > 0 && array_size / nmemb != size)
+    LOG_FATAL("Could not allocate memory");
+
+  return array_size;
+}
+
+void *
+Malloc2(size_t nmemb, size_t size)
+{
+  return Malloc(get_array_size(nmemb, size));
+}
+
+void *
+Realloc2(void *ptr, size_t nmemb, size_t size)
+{
+  return Realloc(ptr, get_array_size(nmemb, size));
+}
+
+char *
+Strdup(const char *s)
+{
+  void *r;
+
+  r = strdup(s);
+  if (!r)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
diff --git a/memory.h b/memory.h
new file mode 100644
index 0000000..7ae2c03
--- /dev/null
+++ b/memory.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for memory functions
+  */
+
+#ifndef GOT_MEMORY_H
+#define GOT_MEMORY_H
+
+#include "sysincl.h"
+
+/* Wrappers checking for errors */
+extern void *Malloc(size_t size);
+extern void *Realloc(void *ptr, size_t size);
+extern void *Malloc2(size_t nmemb, size_t size);
+extern void *Realloc2(void *ptr, size_t nmemb, size_t size);
+extern char *Strdup(const char *s);
+
+/* Convenient macros */
+#define MallocNew(T) ((T *) Malloc(sizeof(T)))
+#define MallocArray(T, n) ((T *) Malloc2(n, sizeof(T)))
+#define ReallocArray(T, n, x) ((T *) Realloc2((void *)(x), n, sizeof(T)))
+#define Free(x) free(x)
+
+#endif /* GOT_MEMORY_H */
diff --git a/nameserv.c b/nameserv.c
new file mode 100644
index 0000000..9f7e648
--- /dev/null
+++ b/nameserv.c
@@ -0,0 +1,166 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2011
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions to do name to IP address conversion
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <netdb.h>
+#include <resolv.h>
+
+#include "nameserv.h"
+#include "socket.h"
+#include "util.h"
+
+/* ================================================== */
+
+static int address_family = IPADDR_UNSPEC;
+
+void
+DNS_SetAddressFamily(int family)
+{
+  address_family = family;
+}
+
+DNS_Status 
+DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  struct addrinfo hints, *res, *ai;
+  int i, result;
+  IPAddr ip;
+
+  max_addrs = MIN(max_addrs, DNS_MAX_ADDRESSES);
+
+  for (i = 0; i < max_addrs; i++)
+    ip_addrs[i].family = IPADDR_UNSPEC;
+
+  /* Avoid calling getaddrinfo() if the name is an IP address */
+  if (UTI_StringToIP(name, &ip)) {
+    if (address_family != IPADDR_UNSPEC && ip.family != address_family)
+      return DNS_Failure;
+    if (max_addrs >= 1)
+      ip_addrs[0] = ip;
+    return DNS_Success;
+  }
+
+  memset(&hints, 0, sizeof (hints));
+
+  switch (address_family) {
+    case IPADDR_INET4:
+      hints.ai_family = AF_INET;
+      break;
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      hints.ai_family = AF_INET6;
+      break;
+#endif
+    default:
+      hints.ai_family = AF_UNSPEC;
+  }
+  hints.ai_socktype = SOCK_DGRAM;
+
+  result = getaddrinfo(name, NULL, &hints, &res);
+
+  if (result) {
+#ifdef FORCE_DNSRETRY
+    return DNS_TryAgain;
+#else
+    return result == EAI_AGAIN ? DNS_TryAgain : DNS_Failure;
+#endif
+  }
+
+  for (ai = res, i = 0; i < max_addrs && ai != NULL; ai = ai->ai_next) {
+    switch (ai->ai_family) {
+      case AF_INET:
+        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET4)
+          continue;
+        ip_addrs[i].family = IPADDR_INET4;
+        ip_addrs[i].addr.in4 = ntohl(((struct sockaddr_in *)ai->ai_addr)->sin_addr.s_addr);
+        i++;
+        break;
+#ifdef FEAT_IPV6
+      case AF_INET6:
+        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET6)
+          continue;
+        /* Don't return an address that would lose a scope ID */
+        if (((struct sockaddr_in6 *)ai->ai_addr)->sin6_scope_id != 0)
+          continue;
+        ip_addrs[i].family = IPADDR_INET6;
+        memcpy(&ip_addrs[i].addr.in6, &((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr.s6_addr,
+               sizeof (ip_addrs->addr.in6));
+        i++;
+        break;
+#endif
+    }
+  }
+
+  freeaddrinfo(res);
+
+  return !max_addrs || ip_addrs[0].family != IPADDR_UNSPEC ? DNS_Success : DNS_Failure;
+}
+
+/* ================================================== */
+
+int
+DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len)
+{
+  char *result = NULL;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 saddr;
+#else
+  struct sockaddr_in saddr;
+#endif
+  IPSockAddr ip_saddr;
+  socklen_t slen;
+  char hbuf[NI_MAXHOST];
+
+  ip_saddr.ip_addr = *ip_addr;
+  ip_saddr.port = 0;
+
+  slen = SCK_IPSockAddrToSockaddr(&ip_saddr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (!getnameinfo((struct sockaddr *)&saddr, slen, hbuf, sizeof (hbuf), NULL, 0, 0))
+    result = hbuf;
+
+  if (result == NULL)
+    result = UTI_IPToString(ip_addr);
+  if (snprintf(name, len, "%s", result) >= len)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+DNS_Reload(void)
+{
+  res_init();
+}
+
+/* ================================================== */
+
diff --git a/nameserv.h b/nameserv.h
new file mode 100644
index 0000000..dbef61a
--- /dev/null
+++ b/nameserv.h
@@ -0,0 +1,52 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module header for nameserver functions
+  */
+
+
+#ifndef GOT_NAMESERV_H
+#define GOT_NAMESERV_H
+
+#include "addressing.h"
+
+typedef enum {
+  DNS_Success,
+  DNS_TryAgain,
+  DNS_Failure
+} DNS_Status;
+
+/* Resolve names only to selected address family */
+extern void DNS_SetAddressFamily(int family);
+
+/* Maximum number of addresses returned by DNS_Name2IPAddress */
+#define DNS_MAX_ADDRESSES 16
+
+extern DNS_Status DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs);
+
+extern int DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len);
+
+extern void DNS_Reload(void);
+
+#endif /* GOT_NAMESERV_H */
+
diff --git a/nameserv_async.c b/nameserv_async.c
new file mode 100644
index 0000000..118443c
--- /dev/null
+++ b/nameserv_async.c
@@ -0,0 +1,130 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions to asynchronously convert name to IP address
+
+  */
+
+#include "config.h"
+#include "sysincl.h"
+
+#include "nameserv_async.h"
+#include "logging.h"
+#include "memory.h"
+#include "privops.h"
+#include "sched.h"
+#include "util.h"
+
+#ifdef USE_PTHREAD_ASYNCDNS
+#include <pthread.h>
+
+/* ================================================== */
+
+struct DNS_Async_Instance {
+  const char *name;
+  DNS_Status status;
+  IPAddr addresses[DNS_MAX_ADDRESSES];
+  DNS_NameResolveHandler handler;
+  void *arg;
+
+  pthread_t thread;
+  int pipe[2];
+};
+
+static pthread_mutex_t privops_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/* ================================================== */
+
+static void *
+start_resolving(void *anything)
+{
+  struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
+
+  pthread_mutex_lock(&privops_lock);
+  inst->status = PRV_Name2IPAddress(inst->name, inst->addresses, DNS_MAX_ADDRESSES);
+  pthread_mutex_unlock(&privops_lock);
+
+  /* Notify the main thread that the result is ready */
+  if (write(inst->pipe[1], "", 1) < 0)
+    ;
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+end_resolving(int fd, int event, void *anything)
+{
+  struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
+  int i;
+
+  if (pthread_join(inst->thread, NULL)) {
+    LOG_FATAL("pthread_join() failed");
+  }
+
+  SCH_RemoveFileHandler(inst->pipe[0]);
+  close(inst->pipe[0]);
+  close(inst->pipe[1]);
+
+  for (i = 0; inst->status == DNS_Success && i < DNS_MAX_ADDRESSES &&
+              inst->addresses[i].family != IPADDR_UNSPEC; i++)
+    ;
+
+  (inst->handler)(inst->status, i, inst->addresses, inst->arg);
+
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+
+  inst = MallocNew(struct DNS_Async_Instance);
+  inst->name = name;
+  inst->handler = handler;
+  inst->arg = anything;
+  inst->status = DNS_Failure;
+
+  if (pipe(inst->pipe)) {
+    LOG_FATAL("pipe() failed");
+  }
+
+  UTI_FdSetCloexec(inst->pipe[0]);
+  UTI_FdSetCloexec(inst->pipe[1]);
+
+  if (pthread_create(&inst->thread, NULL, start_resolving, inst)) {
+    LOG_FATAL("pthread_create() failed");
+  }
+
+  SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, end_resolving, inst);
+}
+
+/* ================================================== */
+
+#else
+#error
+#endif
diff --git a/nameserv_async.h b/nameserv_async.h
new file mode 100644
index 0000000..b8479e1
--- /dev/null
+++ b/nameserv_async.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for asynchronous nameserver functions
+  */
+
+
+#ifndef GOT_NAMESERV_ASYNC_H
+#define GOT_NAMESERV_ASYNC_H
+
+#include "nameserv.h"
+
+/* Function type for callback to process the result */
+typedef void (*DNS_NameResolveHandler)(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *anything);
+
+/* Request resolving of a name to IP address. The handler will be
+   called when the result is available. */
+extern void DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything);
+
+#endif
diff --git a/ntp.h b/ntp.h
new file mode 100644
index 0000000..52b2ab5
--- /dev/null
+++ b/ntp.h
@@ -0,0 +1,182 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file containing common NTP bits and pieces
+  */
+
+#ifndef GOT_NTP_H
+#define GOT_NTP_H
+
+#include "sysincl.h"
+
+#include "hash.h"
+
+typedef struct {
+  uint32_t hi;
+  uint32_t lo;
+} NTP_int64;
+
+typedef uint32_t NTP_int32;
+
+/* The UDP port number used by NTP */
+#define NTP_PORT 123
+
+/* The NTP protocol version that we support */
+#define NTP_VERSION 4
+
+/* Maximum stratum number (infinity) */
+#define NTP_MAX_STRATUM 16
+
+/* Invalid stratum number */
+#define NTP_INVALID_STRATUM 0
+
+/* The minimum and maximum supported length of MAC */
+#define NTP_MIN_MAC_LENGTH (4 + 16)
+#define NTP_MAX_MAC_LENGTH (4 + MAX_HASH_LENGTH)
+
+/* The minimum valid length of an extension field */
+#define NTP_MIN_EF_LENGTH 16
+
+/* The maximum assumed length of all extension fields in an NTP packet,
+   including a MAC (RFC 5905 doesn't specify a limit on length or number of
+   extension fields in one packet) */
+#define NTP_MAX_EXTENSIONS_LENGTH (1024 + NTP_MAX_MAC_LENGTH)
+
+/* The maximum length of MAC in NTPv4 packets which allows deterministic
+   parsing of extension fields (RFC 7822) */
+#define NTP_MAX_V4_MAC_LENGTH (4 + 20)
+
+/* Type definition for leap bits */
+typedef enum {
+  LEAP_Normal = 0,
+  LEAP_InsertSecond = 1,
+  LEAP_DeleteSecond = 2,
+  LEAP_Unsynchronised = 3
+} NTP_Leap;
+
+typedef enum {
+  MODE_UNDEFINED = 0,
+  MODE_ACTIVE = 1,
+  MODE_PASSIVE = 2,
+  MODE_CLIENT = 3,
+  MODE_SERVER = 4,
+  MODE_BROADCAST = 5
+} NTP_Mode;
+
+typedef struct {
+  uint8_t lvm;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  NTP_int32 root_delay;
+  NTP_int32 root_dispersion;
+  NTP_int32 reference_id;
+  NTP_int64 reference_ts;
+  NTP_int64 originate_ts;
+  NTP_int64 receive_ts;
+  NTP_int64 transmit_ts;
+
+  uint8_t extensions[NTP_MAX_EXTENSIONS_LENGTH];
+} NTP_Packet;
+
+#define NTP_HEADER_LENGTH (int)offsetof(NTP_Packet, extensions)
+
+/* Macros to work with the lvm field */
+#define NTP_LVM_TO_LEAP(lvm) (((lvm) >> 6) & 0x3)
+#define NTP_LVM_TO_VERSION(lvm) (((lvm) >> 3) & 0x7)
+#define NTP_LVM_TO_MODE(lvm) ((lvm) & 0x7)
+#define NTP_LVM(leap, version, mode) \
+  ((((leap) << 6) & 0xc0) | (((version) << 3) & 0x38) | ((mode) & 0x07))
+
+/* Special NTP reference IDs */
+#define NTP_REFID_UNSYNC 0x0UL
+#define NTP_REFID_LOCAL 0x7F7F0101UL /* 127.127.1.1 */
+#define NTP_REFID_SMOOTH 0x7F7F01FFUL /* 127.127.1.255 */
+
+/* Non-authentication extension fields and corresponding internal flags */
+
+#define NTP_EF_EXP1                     0xF323
+
+#define NTP_EF_FLAG_EXP1                0x1
+
+/* Pre-NTPv5 experimental extension field */
+typedef struct {
+  uint32_t magic;
+  NTP_int32 root_delay;
+  NTP_int32 root_dispersion;
+  NTP_int64 mono_receive_ts;
+  uint32_t mono_epoch;
+} NTP_ExtFieldExp1;
+
+#define NTP_EF_EXP1_MAGIC 0xF5BEDD9AU
+
+/* Authentication extension fields */
+
+#define NTP_EF_NTS_UNIQUE_IDENTIFIER    0x0104
+#define NTP_EF_NTS_COOKIE               0x0204
+#define NTP_EF_NTS_COOKIE_PLACEHOLDER   0x0304
+#define NTP_EF_NTS_AUTH_AND_EEF         0x0404
+
+/* Enumeration for authentication modes of NTP packets */
+typedef enum {
+  NTP_AUTH_NONE = 0,            /* No authentication */
+  NTP_AUTH_SYMMETRIC,           /* NTP MAC or CMAC using a symmetric key
+                                   (RFC 1305, RFC 5905, RFC 8573) */
+  NTP_AUTH_MSSNTP,              /* MS-SNTP authenticator field */
+  NTP_AUTH_MSSNTP_EXT,          /* MS-SNTP extended authenticator field */
+  NTP_AUTH_NTS,                 /* Network Time Security (RFC 8915) */
+} NTP_AuthMode;
+
+/* Structure describing an NTP packet */
+typedef struct {
+  int length;
+  int version;
+  NTP_Mode mode;
+
+  int ext_fields;
+  int ext_field_flags;
+
+  struct {
+    NTP_AuthMode mode;
+    struct {
+      int start;
+      int length;
+      uint32_t key_id;
+    } mac;
+  } auth;
+} NTP_PacketInfo;
+
+/* Structure used to save NTP measurements.  time is the local time at which
+   the sample is to be considered to have been made and offset is the offset at
+   the time (positive indicates that the local clock is slow relative to the
+   source).  root_delay/root_dispersion include peer_delay/peer_dispersion. */
+typedef struct {
+  struct timespec time;
+  double offset;
+  double peer_delay;
+  double peer_dispersion;
+  double root_delay;
+  double root_dispersion;
+} NTP_Sample;
+
+#endif /* GOT_NTP_H */
diff --git a/ntp_auth.c b/ntp_auth.c
new file mode 100644
index 0000000..58374c5
--- /dev/null
+++ b/ntp_auth.c
@@ -0,0 +1,386 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "keys.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp_auth.h"
+#include "ntp_signd.h"
+#include "nts_ntp.h"
+#include "nts_ntp_client.h"
+#include "nts_ntp_server.h"
+#include "srcparams.h"
+#include "util.h"
+
+/* Structure to hold authentication configuration and state */
+
+struct NAU_Instance_Record {
+  NTP_AuthMode mode;            /* Authentication mode of NTP packets */
+  uint32_t key_id;              /* Identifier of a symmetric key */
+  NNC_Instance nts;             /* Client NTS state */
+};
+
+/* ================================================== */
+
+static int
+generate_symmetric_auth(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  int auth_len, max_auth_len;
+
+  if (info->length + NTP_MIN_MAC_LENGTH > sizeof (*packet)) {
+    DEBUG_LOG("Packet too long");
+    return 0;
+  }
+
+  /* Truncate long MACs in NTPv4 packets to allow deterministic parsing
+     of extension fields (RFC 7822) */
+  max_auth_len = (info->version == 4 ? NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH) - 4;
+  max_auth_len = MIN(max_auth_len, sizeof (*packet) - info->length - 4);
+
+  auth_len = KEY_GenerateAuth(key_id, packet, info->length,
+                              (unsigned char *)packet + info->length + 4, max_auth_len);
+  if (auth_len < NTP_MIN_MAC_LENGTH - 4) {
+    DEBUG_LOG("Could not generate auth data with key %"PRIu32, key_id);
+    return 0;
+  }
+
+  *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+
+  info->auth.mac.start = info->length;
+  info->auth.mac.length = 4 + auth_len;
+  info->auth.mac.key_id = key_id;
+  info->length += info->auth.mac.length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+check_symmetric_auth(NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  int trunc_len;
+
+  if (info->auth.mac.length < NTP_MIN_MAC_LENGTH)
+    return 0;
+
+  trunc_len = info->version == 4 && info->auth.mac.length <= NTP_MAX_V4_MAC_LENGTH ?
+              NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH;
+
+  if (!KEY_CheckAuth(info->auth.mac.key_id, packet, info->auth.mac.start,
+                     (unsigned char *)packet + info->auth.mac.start + 4,
+                     info->auth.mac.length - 4, trunc_len - 4))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static NAU_Instance
+create_instance(NTP_AuthMode mode)
+{
+  NAU_Instance instance;
+
+  instance = MallocNew(struct NAU_Instance_Record);
+  instance->mode = mode;
+  instance->key_id = INACTIVE_AUTHKEY;
+  instance->nts = NULL;
+
+  assert(sizeof (instance->key_id) == 4);
+
+  return instance;
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateNoneInstance(void)
+{
+  return create_instance(NTP_AUTH_NONE);
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateSymmetricInstance(uint32_t key_id)
+{
+  NAU_Instance instance = create_instance(NTP_AUTH_SYMMETRIC);
+
+  instance->key_id = key_id;
+
+  if (!KEY_KeyKnown(key_id))
+    LOG(LOGS_WARN, "Key %"PRIu32" is %s", key_id, "missing");
+  else if (!KEY_CheckKeyLength(key_id))
+    LOG(LOGS_WARN, "Key %"PRIu32" is %s", key_id, "too short");
+
+  return instance;
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set,
+                      uint16_t ntp_port)
+{
+  NAU_Instance instance = create_instance(NTP_AUTH_NTS);
+
+  instance->nts = NNC_CreateInstance(nts_address, name, cert_set, ntp_port);
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+NAU_DestroyInstance(NAU_Instance instance)
+{
+  if (instance->mode == NTP_AUTH_NTS)
+    NNC_DestroyInstance(instance->nts);
+  Free(instance);
+}
+
+/* ================================================== */
+
+int
+NAU_IsAuthEnabled(NAU_Instance instance)
+{
+  return instance->mode != NTP_AUTH_NONE;
+}
+
+/* ================================================== */
+
+int
+NAU_GetSuggestedNtpVersion(NAU_Instance instance)
+{
+  /* If the MAC in NTPv4 packets would be truncated, prefer NTPv3 for
+     compatibility with older chronyd servers */
+  if (instance->mode == NTP_AUTH_SYMMETRIC &&
+      KEY_GetAuthLength(instance->key_id) + sizeof (instance->key_id) > NTP_MAX_V4_MAC_LENGTH)
+    return 3;
+
+  return NTP_VERSION;
+}
+
+/* ================================================== */
+
+int
+NAU_PrepareRequestAuth(NAU_Instance instance)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NTS:
+      if (!NNC_PrepareForAuth(instance->nts))
+        return 0;
+      break;
+    default:
+      break;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request, NTP_PacketInfo *info)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!generate_symmetric_auth(instance->key_id, request, info))
+        return 0;
+      break;
+    case NTP_AUTH_NTS:
+      if (!NNC_GenerateRequestAuth(instance->nts, request, info))
+        return 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  info->auth.mode = instance->mode;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod)
+{
+  *kod = 0;
+
+  switch (info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!check_symmetric_auth(request, info))
+        return 0;
+      break;
+    case NTP_AUTH_MSSNTP:
+      /* MS-SNTP requests are not authenticated */
+      break;
+    case NTP_AUTH_MSSNTP_EXT:
+      /* Not supported yet */
+      return 0;
+    case NTP_AUTH_NTS:
+      if (!NNS_CheckRequestAuth(request, info, kod))
+        return 0;
+      break;
+    default:
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
+                         NTP_Packet *response, NTP_PacketInfo *response_info,
+                         NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                         uint32_t kod)
+{
+  switch (request_info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!generate_symmetric_auth(request_info->auth.mac.key_id, response, response_info))
+        return 0;
+      break;
+    case NTP_AUTH_MSSNTP:
+      /* Sign the packet asynchronously by ntp_signd */
+      if (!NSD_SignAndSendPacket(request_info->auth.mac.key_id, response, response_info,
+                                 remote_addr, local_addr))
+        return 0;
+      /* Don't send the original packet */
+      return 0;
+    case NTP_AUTH_NTS:
+      if (!NNS_GenerateResponseAuth(request, request_info, response, response_info, kod))
+        return 0;
+      break;
+    default:
+      DEBUG_LOG("Could not authenticate response auth_mode=%d", (int)request_info->auth.mode);
+      return 0;
+  }
+
+  response_info->auth.mode = request_info->auth.mode;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response, NTP_PacketInfo *info)
+{
+  /* The authentication must match the expected mode */
+  if (info->auth.mode != instance->mode)
+    return 0;
+
+  switch (info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      /* Check if it is authenticated with the specified key */
+      if (info->auth.mac.key_id != instance->key_id)
+        return 0;
+      /* and that the MAC is valid */
+      if (!check_symmetric_auth(response, info))
+        return 0;
+      break;
+    case NTP_AUTH_NTS:
+      if (!NNC_CheckResponseAuth(instance->nts, response, info))
+        return 0;
+      break;
+    default:
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NAU_ChangeAddress(NAU_Instance instance, IPAddr *address)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+    case NTP_AUTH_SYMMETRIC:
+      break;
+    case NTP_AUTH_NTS:
+      NNC_ChangeAddress(instance->nts, address);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NAU_DumpData(NAU_Instance instance)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NTS:
+      NNC_DumpData(instance->nts);
+      break;
+    default:
+      break;
+  }
+}
+
+/* ================================================== */
+
+void
+NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report)
+{
+  memset(report, 0, sizeof (*report));
+
+  report->mode = instance->mode;
+  report->last_ke_ago = -1;
+
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      report->key_id = instance->key_id;
+      KEY_GetKeyInfo(instance->key_id, &report->key_type, &report->key_length);
+      break;
+    case NTP_AUTH_NTS:
+      NNC_GetReport(instance->nts, report);
+      break;
+    default:
+      assert(0);
+  }
+}
diff --git a/ntp_auth.h b/ntp_auth.h
new file mode 100644
index 0000000..0b8a825
--- /dev/null
+++ b/ntp_auth.h
@@ -0,0 +1,84 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NTP authentication
+  */
+
+#ifndef GOT_NTP_AUTH_H
+#define GOT_NTP_AUTH_H
+
+#include "addressing.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef struct NAU_Instance_Record *NAU_Instance;
+
+/* Create an authenticator instance in a specific mode */
+extern NAU_Instance NAU_CreateNoneInstance(void);
+extern NAU_Instance NAU_CreateSymmetricInstance(uint32_t key_id);
+extern NAU_Instance NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name,
+                                          uint32_t cert_set, uint16_t ntp_port);
+
+/* Destroy an instance */
+extern void NAU_DestroyInstance(NAU_Instance instance);
+
+/* Check if an instance is not in the None mode */
+extern int NAU_IsAuthEnabled(NAU_Instance instance);
+
+/* Get NTP version recommended for better compatibility */
+extern int NAU_GetSuggestedNtpVersion(NAU_Instance instance);
+
+/* Perform operations necessary for NAU_GenerateRequestAuth() */
+extern int NAU_PrepareRequestAuth(NAU_Instance instance);
+
+/* Extend a request with data required by the authentication mode */
+extern int NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request,
+                                   NTP_PacketInfo *info);
+
+/* Verify that a request is authentic.  If it is not authentic and a non-zero
+   kod code is returned, a KoD response should be sent back. */
+extern int NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod);
+
+/* Extend a response with data required by the authentication mode.  This
+   function can be called only if the previous call of NAU_CheckRequestAuth()
+   was on the same request. */
+extern int NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
+                                    NTP_Packet *response, NTP_PacketInfo *response_info,
+                                    NTP_Remote_Address *remote_addr,
+                                    NTP_Local_Address *local_addr,
+                                    uint32_t kod);
+
+/* Verify that a response is authentic */
+extern int NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response,
+                                 NTP_PacketInfo *info);
+
+/* Change an authentication-specific address (e.g. after replacing a source) */
+extern void NAU_ChangeAddress(NAU_Instance instance, IPAddr *address);
+
+/* Save authentication-specific data to speed up the next start */
+extern void NAU_DumpData(NAU_Instance instance);
+
+/* Provide a report about the current authentication state */
+extern void NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report);
+
+#endif
diff --git a/ntp_core.c b/ntp_core.c
new file mode 100644
index 0000000..63c5a3a
--- /dev/null
+++ b/ntp_core.c
@@ -0,0 +1,2999 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Core NTP protocol engine
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "ntp_auth.h"
+#include "ntp_core.h"
+#include "ntp_ext.h"
+#include "ntp_io.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "sched.h"
+#include "reference.h"
+#include "local.h"
+#include "samplefilt.h"
+#include "smooth.h"
+#include "sources.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "addrfilt.h"
+#include "clientlog.h"
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+static int log_raw_measurements;
+
+/* ================================================== */
+/* Enumeration used for remembering the operating mode of one of the
+   sources */
+
+typedef enum {
+  MD_OFFLINE,                   /* No sampling at all */
+  MD_ONLINE,                    /* Normal sampling based on sampling interval */
+  MD_BURST_WAS_OFFLINE,         /* Burst sampling, return to offline afterwards */
+  MD_BURST_WAS_ONLINE,          /* Burst sampling, return to online afterwards */
+} OperatingMode;
+
+/* ================================================== */
+/* Structure used for holding a single peer/server's
+   protocol machine */
+
+struct NCR_Instance_Record {
+  NTP_Remote_Address remote_addr; /* Needed for routing transmit packets */
+  NTP_Local_Address local_addr; /* Local address/socket used to send packets */
+  NTP_Mode mode;                /* The source's NTP mode
+                                   (client/server or symmetric active peer) */
+  int interleaved;              /* Boolean enabling interleaved NTP mode */
+  OperatingMode opmode;         /* Whether we are sampling this source
+                                   or not and in what way */
+  SCH_TimeoutID rx_timeout_id;  /* Timeout ID for latest received response */
+  SCH_TimeoutID tx_timeout_id;  /* Timeout ID for next transmission */
+  int tx_suspended;             /* Boolean indicating we can't transmit yet */
+
+  int auto_iburst;              /* If 1, initiate a burst when going online */
+  int auto_burst;               /* If 1, initiate a burst on each poll */
+  int auto_offline;             /* If 1, automatically go offline when requests
+                                   cannot be sent */
+
+  int local_poll;               /* Log2 of polling interval at our end */
+  int remote_poll;              /* Log2 of server/peer's polling interval (recovered
+                                   from received packets) */
+  int remote_stratum;           /* Stratum of the server/peer (recovered from
+                                   received packets) */
+  double remote_root_delay;     /* Root delay from last valid packet */
+  double remote_root_dispersion;/* Root dispersion from last valid packet */
+
+  int presend_minpoll;           /* If the current polling interval is
+                                    at least this, an extra client packet
+                                    will be send some time before normal
+                                    transmit.  This ensures that both
+                                    us and the server/peer have an ARP
+                                    entry for each other ready, which
+                                    means our measurement is not
+                                    botched by an ARP round-trip on one
+                                    side or the other. */
+
+  int presend_done;             /* The presend packet has been sent */
+
+  int minpoll;                  /* Log2 of minimum defined polling interval */
+  int maxpoll;                  /* Log2 of maximum defined polling interval */
+
+  int min_stratum;              /* Increase stratum in received packets to the
+                                   minimum */
+
+  int copy;                     /* Boolean suppressing own refid and stratum */
+
+  int poll_target;              /* Target number of sourcestats samples */
+
+  int version;                  /* Version set in packets for server/peer */
+
+  double poll_score;            /* Score of current local poll */
+
+  double max_delay;             /* Maximum round-trip delay to the
+                                   peer that we can tolerate and still
+                                   use the sample for generating
+                                   statistics from */
+
+  double max_delay_ratio;       /* Largest ratio of delay /
+                                   min_delay_in_register that we can
+                                   tolerate.  */
+
+  double max_delay_dev_ratio;   /* Maximum ratio of increase in delay / stddev */
+
+  double offset_correction;     /* Correction applied to measured offset
+                                   (e.g. for asymmetry in network delay) */
+
+  int ext_field_flags;          /* Enabled extension fields */
+
+  uint32_t remote_mono_epoch;   /* ID of the source's monotonic scale */
+  double mono_doffset;          /* Accumulated offset between source's
+                                   real-time and monotonic scales */
+
+  NAU_Instance auth;            /* Authentication */
+
+  /* Count of transmitted packets since last valid response */
+  unsigned int tx_count;
+
+  /* Flag indicating a valid response was received since last request */
+  int valid_rx;
+
+  /* Flag indicating the timestamps below are from a valid packet and may
+     be used for synchronisation */
+  int valid_timestamps;
+
+  /* Receive and transmit timestamps from the last valid response */
+  NTP_int64 remote_ntp_monorx;
+  NTP_int64 remote_ntp_rx;
+  NTP_int64 remote_ntp_tx;
+
+  /* Local timestamp when the last valid response was received from the
+     source.  We have to be prepared to tinker with this if the local
+     clock has its frequency adjusted before we repond.  The value we
+     store here is what our own local time was when the same arrived.
+     Before replying, we have to correct this to fit with the
+     parameters for the current reference.  (It must be stored
+     relative to local time to permit frequency and offset adjustments
+     to be made when we trim the local clock). */
+  NTP_int64 local_ntp_rx;
+  NTP_Local_Timestamp local_rx;
+
+  /* Local timestamp when we last transmitted a packet to the source.
+     We store two versions.  The first is in NTP format, and is used
+     to validate the next received packet from the source.
+     Additionally, this is corrected to bring it into line with the
+     current reference.  The second is in timespec format, and is kept
+     relative to the local clock.  We modify this in accordance with
+     local clock frequency/offset changes, and use this for computing
+     statistics about the source when a return packet arrives. */
+  NTP_int64 local_ntp_tx;
+  NTP_Local_Timestamp local_tx;
+
+  /* Previous values of some variables needed in interleaved mode */
+  NTP_Local_Timestamp prev_local_tx;
+  int prev_local_poll;
+  unsigned int prev_tx_count;
+
+  /* Flag indicating the two timestamps below were updated since the
+     last transmission */
+  int updated_init_timestamps;
+
+  /* Timestamps used for (re)starting the symmetric protocol, when we
+     need to respond to a packet which is not a valid response */
+  NTP_int64 init_remote_ntp_tx;
+  NTP_Local_Timestamp init_local_rx;
+
+  /* The instance record in the main source management module.  This
+     performs the statistical analysis on the samples we generate */
+
+  SRC_Instance source;
+
+  /* Optional long-term quantile estimate of peer delay */
+  QNT_Instance delay_quant;
+
+  /* Optional median filter for NTP measurements */
+  SPF_Instance filter;
+  int filter_count;
+
+  int burst_good_samples_to_go;
+  int burst_total_samples_to_go;
+
+  /* Report from last valid response */
+  RPT_NTPReport report;
+};
+
+typedef struct {
+  NTP_Remote_Address addr;
+  NTP_Local_Address local_addr;
+  NAU_Instance auth;
+  int interval;
+} BroadcastDestination;
+
+/* Array of BroadcastDestination */
+static ARR_Instance broadcasts;
+
+/* ================================================== */
+/* Initial delay period before first packet is transmitted (in seconds) */
+#define INITIAL_DELAY 0.2
+
+/* Spacing required between samples for any two servers/peers (to
+   minimise risk of network collisions) (in seconds) */
+#define MIN_SAMPLING_SEPARATION 0.002
+#define MAX_SAMPLING_SEPARATION 0.2
+
+/* Randomness added to spacing between samples for one server/peer */
+#define SAMPLING_RANDOMNESS 0.02
+
+/* Adjustment of the peer polling interval */
+#define PEER_SAMPLING_ADJ 1.1
+
+/* Maximum spacing between samples in the burst mode as an absolute
+   value and ratio to the normal polling interval */
+#define MAX_BURST_INTERVAL 2.0
+#define MAX_BURST_POLL_RATIO 0.25
+
+/* Number of samples in initial burst */
+#define IBURST_GOOD_SAMPLES 4
+#define IBURST_TOTAL_SAMPLES SOURCE_REACH_BITS
+
+/* Number of samples in automatic burst */
+#define BURST_GOOD_SAMPLES 1
+#define MAX_BURST_TOTAL_SAMPLES 4
+
+/* Time to wait after sending packet to 'warm up' link */
+#define WARM_UP_DELAY 2.0
+
+/* Compatible NTP protocol versions */
+#define NTP_MAX_COMPAT_VERSION NTP_VERSION
+#define NTP_MIN_COMPAT_VERSION 1
+
+/* Maximum allowed dispersion - as defined in RFC 5905 (16 seconds) */
+#define NTP_MAX_DISPERSION 16.0
+
+/* Maximum allowed time for server to process client packet */
+#define MAX_SERVER_INTERVAL 4.0
+
+/* Maximum acceptable delay in transmission for timestamp correction */
+#define MAX_TX_DELAY 1.0
+
+/* Maximum allowed values of maxdelay parameters */
+#define MAX_MAXDELAY 1.0e3
+#define MAX_MAXDELAYRATIO 1.0e6
+#define MAX_MAXDELAYDEVRATIO 1.0e6
+
+/* Parameters for the peer delay quantile */
+#define DELAY_QUANT_Q 100
+#define DELAY_QUANT_REPEAT 7
+
+/* Minimum and maximum allowed poll interval */
+#define MIN_POLL -7
+#define MAX_POLL 24
+
+/* Enable sub-second polling intervals only when the peer delay is not
+   longer than 10 milliseconds to restrict them to local networks */
+#define MIN_NONLAN_POLL 0
+#define MAX_LAN_PEER_DELAY 0.01
+
+/* Kiss-o'-Death codes */
+#define KOD_RATE 0x52415445UL /* RATE */
+
+/* Maximum poll interval set by KoD RATE */
+#define MAX_KOD_RATE_POLL SRC_DEFAULT_MAXPOLL
+
+/* Maximum number of missed responses to accept samples using old timestamps
+   in the interleaved client/server mode */
+#define MAX_CLIENT_INTERLEAVED_TX 4
+
+/* Maximum ratio of local intervals in the timestamp selection of the
+   interleaved mode to prefer a sample using previous timestamps */
+#define MAX_INTERLEAVED_L2L_RATIO 0.1
+
+/* Maximum acceptable change in server mono<->real offset */
+#define MAX_MONO_DOFFSET 16.0
+
+/* Invalid socket, different from the one in ntp_io.c */
+#define INVALID_SOCK_FD -2
+
+/* ================================================== */
+
+/* Server IPv4/IPv6 sockets */
+static int server_sock_fd4;
+static int server_sock_fd6;
+
+static ADF_AuthTable access_auth_table;
+
+/* Current offset between monotonic and cooked time, and its epoch ID
+   which is reset on clock steps */
+static double server_mono_offset;
+static uint32_t server_mono_epoch;
+
+/* Characters for printing synchronisation status and timestamping source */
+static const char leap_chars[4] = {'N', '+', '-', '?'};
+static const char tss_chars[3] = {'D', 'K', 'H'};
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void transmit_timeout(void *arg);
+static double get_transmit_delay(NCR_Instance inst, int on_tx, double last_tx);
+static double get_separation(int poll);
+static int parse_packet(NTP_Packet *packet, int length, NTP_PacketInfo *info);
+static void process_sample(NCR_Instance inst, NTP_Sample *sample);
+static void set_connectivity(NCR_Instance inst, SRC_Connectivity connectivity);
+
+/* ================================================== */
+
+static void
+do_size_checks(void)
+{
+  /* Assertions to check the sizes of certain data types
+     and the positions of certain record fields */
+
+  /* Check that certain invariants are true */
+  assert(sizeof(NTP_int32) == 4);
+  assert(sizeof(NTP_int64) == 8);
+
+  /* Check offsets of all fields in the NTP packet format */
+  assert(offsetof(NTP_Packet, lvm)             ==  0);
+  assert(offsetof(NTP_Packet, stratum)         ==  1);
+  assert(offsetof(NTP_Packet, poll)            ==  2);
+  assert(offsetof(NTP_Packet, precision)       ==  3);
+  assert(offsetof(NTP_Packet, root_delay)      ==  4);
+  assert(offsetof(NTP_Packet, root_dispersion) ==  8);
+  assert(offsetof(NTP_Packet, reference_id)    == 12);
+  assert(offsetof(NTP_Packet, reference_ts)    == 16);
+  assert(offsetof(NTP_Packet, originate_ts)    == 24);
+  assert(offsetof(NTP_Packet, receive_ts)      == 32);
+  assert(offsetof(NTP_Packet, transmit_ts)     == 40);
+}
+
+/* ================================================== */
+
+static void
+do_time_checks(void)
+{
+  struct timespec now;
+  time_t warning_advance = 3600 * 24 * 365 * 10; /* 10 years */
+
+#ifdef HAVE_LONG_TIME_T
+  /* Check that time before NTP_ERA_SPLIT underflows correctly */
+
+  struct timespec ts1 = {NTP_ERA_SPLIT, 1}, ts2 = {NTP_ERA_SPLIT - 1, 1};
+  NTP_int64 nts1, nts2;
+  int r;
+
+  UTI_TimespecToNtp64(&ts1, &nts1, NULL);
+  UTI_TimespecToNtp64(&ts2, &nts2, NULL);
+  UTI_Ntp64ToTimespec(&nts1, &ts1);
+  UTI_Ntp64ToTimespec(&nts2, &ts2);
+
+  r = ts1.tv_sec == NTP_ERA_SPLIT &&
+      ts1.tv_sec + (1ULL << 32) - 1 == ts2.tv_sec;
+
+  assert(r);
+
+  LCL_ReadRawTime(&now);
+  if (ts2.tv_sec - now.tv_sec < warning_advance)
+    LOG(LOGS_WARN, "Assumed NTP time ends at %s!", UTI_TimeToLogForm(ts2.tv_sec));
+#else
+  LCL_ReadRawTime(&now);
+  if (now.tv_sec > 0x7fffffff - warning_advance)
+    LOG(LOGS_WARN, "System time ends at %s!", UTI_TimeToLogForm(0x7fffffff));
+#endif
+}
+
+/* ================================================== */
+
+static void
+zero_local_timestamp(NTP_Local_Timestamp *ts)
+{
+  UTI_ZeroTimespec(&ts->ts);
+  ts->err = 0.0;
+  ts->source = NTP_TS_DAEMON;
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type == LCL_ChangeAdjust) {
+    server_mono_offset += doffset;
+  } else {
+    UTI_GetRandomBytes(&server_mono_epoch, sizeof (server_mono_epoch));
+    server_mono_offset = 0.0;
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_Initialise(void)
+{
+  do_size_checks();
+  do_time_checks();
+
+  logfileid = CNF_GetLogMeasurements(&log_raw_measurements) ? LOG_FileOpen("measurements",
+      "   Date (UTC) Time     IP Address   L St 123 567 ABCD  LP RP Score    Offset  Peer del. Peer disp.  Root del. Root disp. Refid     MTxRx")
+    : -1;
+
+  access_auth_table = ADF_CreateTable();
+  broadcasts = ARR_CreateInstance(sizeof (BroadcastDestination));
+
+  /* Server socket will be opened when access is allowed */
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+  handle_slew(NULL, NULL, 0.0, 0.0, LCL_ChangeUnknownStep, NULL);
+}
+
+/* ================================================== */
+
+void
+NCR_Finalise(void)
+{
+  unsigned int i;
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  if (server_sock_fd4 != INVALID_SOCK_FD)
+    NIO_CloseServerSocket(server_sock_fd4);
+  if (server_sock_fd6 != INVALID_SOCK_FD)
+    NIO_CloseServerSocket(server_sock_fd6);
+
+  for (i = 0; i < ARR_GetSize(broadcasts); i++) {
+    NIO_CloseServerSocket(((BroadcastDestination *)ARR_GetElement(broadcasts, i))->local_addr.sock_fd);
+    NAU_DestroyInstance(((BroadcastDestination *)ARR_GetElement(broadcasts, i))->auth);
+  }
+
+  ARR_DestroyInstance(broadcasts);
+  ADF_DestroyTable(access_auth_table);
+}
+
+/* ================================================== */
+
+static void
+restart_timeout(NCR_Instance inst, double delay)
+{
+  /* Check if we can transmit */
+  if (inst->tx_suspended) {
+    assert(!inst->tx_timeout_id);
+    return;
+  }
+
+  /* Stop both rx and tx timers if running */
+  SCH_RemoveTimeout(inst->rx_timeout_id);
+  inst->rx_timeout_id = 0;
+  SCH_RemoveTimeout(inst->tx_timeout_id);
+
+  /* Start new timer for transmission */
+  inst->tx_timeout_id = SCH_AddTimeoutInClass(delay, get_separation(inst->local_poll),
+                                              SAMPLING_RANDOMNESS,
+                                              inst->mode == MODE_CLIENT ?
+                                                SCH_NtpClientClass : SCH_NtpPeerClass,
+                                              transmit_timeout, (void *)inst);
+}
+
+/* ================================================== */
+
+static void
+start_initial_timeout(NCR_Instance inst)
+{
+  double delay, last_tx;
+  struct timespec now;
+
+  if (!inst->tx_timeout_id) {
+    /* This will be the first transmission after mode change */
+
+    /* Mark source active */
+    SRC_SetActive(inst->source);
+  }
+
+  /* In case the offline period was too short, adjust the delay to keep
+     the interval between packets at least as long as the current polling
+     interval */
+  if (!UTI_IsZeroTimespec(&inst->local_tx.ts)) {
+    SCH_GetLastEventTime(&now, NULL, NULL);
+    last_tx = UTI_DiffTimespecsToDouble(&now, &inst->local_tx.ts);
+    if (last_tx < 0.0)
+      last_tx = 0.0;
+    delay = get_transmit_delay(inst, 0, 0.0) - last_tx;
+  } else {
+    delay = 0.0;
+  }
+
+  if (delay < INITIAL_DELAY)
+    delay = INITIAL_DELAY;
+
+  restart_timeout(inst, delay);
+}
+
+/* ================================================== */
+
+static void
+close_client_socket(NCR_Instance inst)
+{
+  if (inst->mode == MODE_CLIENT && inst->local_addr.sock_fd != INVALID_SOCK_FD) {
+    NIO_CloseClientSocket(inst->local_addr.sock_fd);
+    inst->local_addr.sock_fd = INVALID_SOCK_FD;
+  }
+
+  SCH_RemoveTimeout(inst->rx_timeout_id);
+  inst->rx_timeout_id = 0;
+}
+
+/* ================================================== */
+
+static void
+take_offline(NCR_Instance inst)
+{
+  inst->opmode = MD_OFFLINE;
+
+  SCH_RemoveTimeout(inst->tx_timeout_id);
+  inst->tx_timeout_id = 0;
+
+  /* Mark source unreachable */
+  SRC_ResetReachability(inst->source);
+
+  /* And inactive */
+  SRC_UnsetActive(inst->source);
+
+  close_client_socket(inst);
+
+  NCR_ResetInstance(inst);
+}
+
+/* ================================================== */
+
+static void
+reset_report(NCR_Instance inst)
+{
+  memset(&inst->report, 0, sizeof (inst->report));
+  inst->report.remote_addr = inst->remote_addr.ip_addr;
+  inst->report.remote_port = inst->remote_addr.port;
+}
+
+/* ================================================== */
+
+NCR_Instance
+NCR_CreateInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                   SourceParameters *params, const char *name)
+{
+  NCR_Instance result;
+
+  result = MallocNew(struct NCR_Instance_Record);
+
+  result->remote_addr = *remote_addr;
+  result->local_addr.ip_addr.family = IPADDR_UNSPEC;
+  result->local_addr.if_index = INVALID_IF_INDEX;
+
+  switch (type) {
+    case NTP_SERVER:
+      /* Client socket will be obtained when sending request */
+      result->local_addr.sock_fd = INVALID_SOCK_FD;
+      result->mode = MODE_CLIENT;
+      break;
+    case NTP_PEER:
+      result->local_addr.sock_fd = NIO_OpenServerSocket(remote_addr);
+      result->mode = MODE_ACTIVE;
+      break;
+    default:
+      assert(0);
+  }
+
+  result->interleaved = params->interleaved;
+
+  result->minpoll = params->minpoll;
+  if (result->minpoll < MIN_POLL)
+    result->minpoll = SRC_DEFAULT_MINPOLL;
+  else if (result->minpoll > MAX_POLL)
+    result->minpoll = MAX_POLL;
+
+  result->maxpoll = params->maxpoll;
+  if (result->maxpoll < MIN_POLL)
+    result->maxpoll = SRC_DEFAULT_MAXPOLL;
+  else if (result->maxpoll > MAX_POLL)
+    result->maxpoll = MAX_POLL;
+  if (result->maxpoll < result->minpoll)
+    result->maxpoll = result->minpoll;
+
+  result->min_stratum = params->min_stratum;
+  if (result->min_stratum >= NTP_MAX_STRATUM)
+    result->min_stratum = NTP_MAX_STRATUM - 1;
+
+  /* Presend doesn't work in symmetric mode */
+  result->presend_minpoll = params->presend_minpoll;
+  if (result->presend_minpoll <= MAX_POLL && result->mode != MODE_CLIENT)
+    result->presend_minpoll = MAX_POLL + 1;
+
+  result->max_delay = CLAMP(0.0, params->max_delay, MAX_MAXDELAY);
+  result->max_delay_ratio = CLAMP(0.0, params->max_delay_ratio, MAX_MAXDELAYRATIO);
+  result->max_delay_dev_ratio = CLAMP(0.0, params->max_delay_dev_ratio, MAX_MAXDELAYDEVRATIO);
+  result->offset_correction = params->offset;
+  result->auto_iburst = params->iburst;
+  result->auto_burst = params->burst;
+  result->auto_offline = params->auto_offline;
+  result->copy = params->copy && result->mode == MODE_CLIENT;
+  result->poll_target = params->poll_target;
+  result->ext_field_flags = params->ext_fields;
+
+  if (params->nts) {
+    IPSockAddr nts_address;
+
+    if (result->mode == MODE_ACTIVE)
+      LOG(LOGS_WARN, "NTS not supported with peers");
+
+    nts_address.ip_addr = remote_addr->ip_addr;
+    nts_address.port = params->nts_port;
+
+    result->auth = NAU_CreateNtsInstance(&nts_address, name, params->cert_set,
+                                         result->remote_addr.port);
+  } else if (params->authkey != INACTIVE_AUTHKEY) {
+    result->auth = NAU_CreateSymmetricInstance(params->authkey);
+  } else {
+    result->auth = NAU_CreateNoneInstance();
+  }
+
+  if (result->ext_field_flags || result->interleaved)
+    result->version = NTP_VERSION;
+  else
+    result->version = NAU_GetSuggestedNtpVersion(result->auth);
+
+  if (params->version)
+    result->version = CLAMP(NTP_MIN_COMPAT_VERSION, params->version, NTP_VERSION);
+
+  /* Create a source instance for this NTP source */
+  result->source = SRC_CreateNewInstance(UTI_IPToRefid(&remote_addr->ip_addr),
+                                         SRC_NTP, NAU_IsAuthEnabled(result->auth),
+                                         params->sel_options, &result->remote_addr.ip_addr,
+                                         params->min_samples, params->max_samples,
+                                         params->min_delay, params->asymmetry);
+
+  if (params->max_delay_quant > 0.0) {
+    int k = round(CLAMP(0.05, params->max_delay_quant, 0.95) * DELAY_QUANT_Q);
+    result->delay_quant = QNT_CreateInstance(k, k, DELAY_QUANT_Q, DELAY_QUANT_REPEAT,
+                                             LCL_GetSysPrecisionAsQuantum() / 2.0);
+  } else {
+    result->delay_quant = NULL;
+  }
+
+  if (params->filter_length >= 1)
+    result->filter = SPF_CreateInstance(1, params->filter_length, NTP_MAX_DISPERSION, 0.0);
+  else
+    result->filter = NULL;
+
+  result->rx_timeout_id = 0;
+  result->tx_timeout_id = 0;
+  result->tx_suspended = 1;
+  result->opmode = MD_OFFLINE;
+  result->local_poll = MAX(result->minpoll, MIN_NONLAN_POLL);
+  result->poll_score = 0.0;
+  zero_local_timestamp(&result->local_tx);
+  result->burst_good_samples_to_go = 0;
+  result->burst_total_samples_to_go = 0;
+  
+  NCR_ResetInstance(result);
+
+  set_connectivity(result, params->connectivity);
+
+  reset_report(result);
+
+  return result;
+}
+
+/* ================================================== */
+
+/* Destroy an instance */
+void
+NCR_DestroyInstance(NCR_Instance instance)
+{
+  if (instance->opmode != MD_OFFLINE)
+    take_offline(instance);
+
+  if (instance->mode == MODE_ACTIVE)
+    NIO_CloseServerSocket(instance->local_addr.sock_fd);
+
+  if (instance->delay_quant)
+    QNT_DestroyInstance(instance->delay_quant);
+  if (instance->filter)
+    SPF_DestroyInstance(instance->filter);
+
+  NAU_DestroyInstance(instance->auth);
+
+  /* This will destroy the source instance inside the
+     structure, which will cause reselection if this was the
+     synchronising source etc. */
+  SRC_DestroyInstance(instance->source);
+
+  /* Free the data structure */
+  Free(instance);
+}
+
+/* ================================================== */
+
+void
+NCR_StartInstance(NCR_Instance instance)
+{
+  instance->tx_suspended = 0;
+  if (instance->opmode != MD_OFFLINE)
+    start_initial_timeout(instance);
+}
+
+/* ================================================== */
+
+void
+NCR_ResetInstance(NCR_Instance instance)
+{
+  instance->tx_count = 0;
+  instance->presend_done = 0;
+
+  instance->remote_poll = 0;
+  instance->remote_stratum = 0;
+  instance->remote_root_delay = 0.0;
+  instance->remote_root_dispersion = 0.0;
+  instance->remote_mono_epoch = 0;
+  instance->mono_doffset = 0.0;
+
+  instance->valid_rx = 0;
+  instance->valid_timestamps = 0;
+  UTI_ZeroNtp64(&instance->remote_ntp_monorx);
+  UTI_ZeroNtp64(&instance->remote_ntp_rx);
+  UTI_ZeroNtp64(&instance->remote_ntp_tx);
+  UTI_ZeroNtp64(&instance->local_ntp_rx);
+  UTI_ZeroNtp64(&instance->local_ntp_tx);
+  zero_local_timestamp(&instance->local_rx);
+
+  zero_local_timestamp(&instance->prev_local_tx);
+  instance->prev_local_poll = 0;
+  instance->prev_tx_count = 0;
+
+  instance->updated_init_timestamps = 0;
+  UTI_ZeroNtp64(&instance->init_remote_ntp_tx);
+  zero_local_timestamp(&instance->init_local_rx);
+
+  if (instance->delay_quant)
+    QNT_Reset(instance->delay_quant);
+  if (instance->filter)
+    SPF_DropSamples(instance->filter);
+  instance->filter_count = 0;
+}
+
+/* ================================================== */
+
+void
+NCR_ResetPoll(NCR_Instance instance)
+{
+  if (instance->local_poll != instance->minpoll) {
+    instance->local_poll = instance->minpoll;
+
+    /* The timer was set with a longer poll interval, restart it */
+    if (instance->tx_timeout_id)
+      restart_timeout(instance, get_transmit_delay(instance, 0, 0.0));
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_ChangeRemoteAddress(NCR_Instance inst, NTP_Remote_Address *remote_addr, int ntp_only)
+{
+  NCR_ResetInstance(inst);
+
+  if (!ntp_only)
+    NAU_ChangeAddress(inst->auth, &remote_addr->ip_addr);
+
+  inst->remote_addr = *remote_addr;
+
+  if (inst->mode == MODE_CLIENT)
+    close_client_socket(inst);
+  else {
+    NIO_CloseServerSocket(inst->local_addr.sock_fd);
+    inst->local_addr.ip_addr.family = IPADDR_UNSPEC;
+    inst->local_addr.if_index = INVALID_IF_INDEX;
+    inst->local_addr.sock_fd = NIO_OpenServerSocket(remote_addr);
+  }
+
+  /* Update the reference ID and reset the source/sourcestats instances */
+  SRC_SetRefid(inst->source, UTI_IPToRefid(&remote_addr->ip_addr),
+               &inst->remote_addr.ip_addr);
+  SRC_ResetInstance(inst->source);
+
+  reset_report(inst);
+}
+
+/* ================================================== */
+
+static void
+adjust_poll(NCR_Instance inst, double adj)
+{
+  NTP_Sample last_sample;
+
+  inst->poll_score += adj;
+
+  if (inst->poll_score >= 1.0) {
+    inst->local_poll += (int)inst->poll_score;
+    inst->poll_score -= (int)inst->poll_score;
+  }
+
+  if (inst->poll_score < 0.0) {
+    inst->local_poll += (int)(inst->poll_score - 1.0);
+    inst->poll_score -= (int)(inst->poll_score - 1.0);
+  }
+  
+  /* Clamp polling interval to defined range */
+  if (inst->local_poll < inst->minpoll) {
+    inst->local_poll = inst->minpoll;
+    inst->poll_score = 0;
+  } else if (inst->local_poll > inst->maxpoll) {
+    inst->local_poll = inst->maxpoll;
+    inst->poll_score = 1.0;
+  }
+
+  /* Don't allow a sub-second polling interval if the source is not reachable
+     or it is not in a local network according to the measured delay */
+  if (inst->local_poll < MIN_NONLAN_POLL &&
+      (!SRC_IsReachable(inst->source) ||
+       (SST_MinRoundTripDelay(SRC_GetSourcestats(inst->source)) > MAX_LAN_PEER_DELAY &&
+        (!inst->filter || !SPF_GetLastSample(inst->filter, &last_sample) ||
+         last_sample.peer_delay > MAX_LAN_PEER_DELAY))))
+    inst->local_poll = MIN_NONLAN_POLL;
+}
+
+/* ================================================== */
+
+static double
+get_poll_adj(NCR_Instance inst, double error_in_estimate, double peer_distance)
+{
+  double poll_adj;
+  int samples;
+
+  if (error_in_estimate > peer_distance) {
+    /* If the prediction is not even within +/- the peer distance of the peer,
+       we are clearly not tracking the peer at all well, so we back off the
+       sampling rate depending on just how bad the situation is */
+    poll_adj = -log(error_in_estimate / peer_distance) / log(2.0);
+  } else {
+    samples = SST_Samples(SRC_GetSourcestats(inst->source));
+
+    /* Adjust polling interval so that the number of sourcestats samples
+       remains close to the target value */
+    poll_adj = ((double)samples / inst->poll_target - 1.0) / inst->poll_target;
+
+    /* Make interval shortening quicker */
+    if (samples < inst->poll_target) {
+      poll_adj *= 2.0;
+    }
+  }
+
+  return poll_adj;
+}
+
+/* ================================================== */
+
+static int
+get_transmit_poll(NCR_Instance inst)
+{
+  int poll;
+
+  poll = inst->local_poll;
+
+  /* In symmetric mode, if the peer is responding, use shorter of the local
+     and remote poll interval, but not shorter than the minimum */
+  if (inst->mode == MODE_ACTIVE && poll > inst->remote_poll &&
+      SRC_IsReachable(inst->source))
+    poll = MAX(inst->remote_poll, inst->minpoll);
+
+  return poll;
+}
+
+/* ================================================== */
+
+static double
+get_transmit_delay(NCR_Instance inst, int on_tx, double last_tx)
+{
+  int poll_to_use, stratum_diff;
+  double delay_time;
+
+  /* If we're in burst mode, queue for immediate dispatch.
+
+     If we're operating in client/server mode, queue the timeout for
+     the poll interval hence.  The fact that a timeout has been queued
+     in the transmit handler is immaterial - that is only done so that
+     we at least send something, if no reply is heard.
+
+     If we're in symmetric mode, we have to take account of the peer's
+     wishes, otherwise his sampling regime will fall to pieces.  If
+     we're in client/server mode, we don't care what poll interval the
+     server responded with last time. */
+
+  poll_to_use = get_transmit_poll(inst);
+  delay_time = UTI_Log2ToDouble(poll_to_use);
+
+  switch (inst->opmode) {
+    case MD_OFFLINE:
+      assert(0);
+      break;
+    case MD_ONLINE:
+      switch(inst->mode) {
+        case MODE_CLIENT:
+          if (inst->presend_done)
+            delay_time = WARM_UP_DELAY;
+          break;
+
+        case MODE_ACTIVE:
+          /* If the remote stratum is higher than ours, wait a bit for the next
+             packet before responding in order to minimize the delay of the
+             measurement and its error for the peer which has higher stratum.
+             If the remote stratum is equal to ours, try to interleave packets
+             evenly with the peer. */
+          stratum_diff = inst->remote_stratum - REF_GetOurStratum();
+          if ((stratum_diff > 0 && last_tx * PEER_SAMPLING_ADJ < delay_time) ||
+              (!on_tx && !stratum_diff &&
+               last_tx / delay_time > PEER_SAMPLING_ADJ - 0.5))
+            delay_time *= PEER_SAMPLING_ADJ;
+
+          /* Substract the already spend time */
+          if (last_tx > 0.0)
+            delay_time -= last_tx;
+          if (delay_time < 0.0)
+            delay_time = 0.0;
+
+          break;
+        default:
+          assert(0);
+          break;
+      }
+      break;
+
+    case MD_BURST_WAS_ONLINE:
+    case MD_BURST_WAS_OFFLINE:
+      /* Burst modes */
+      delay_time = MIN(MAX_BURST_INTERVAL, MAX_BURST_POLL_RATIO * delay_time);
+      break;
+    default:
+      assert(0);
+      break;
+  }
+
+  return delay_time;
+}
+
+/* ================================================== */
+/* Calculate sampling separation for given polling interval */
+
+static double
+get_separation(int poll)
+{
+  double separation;
+
+  assert(poll >= MIN_POLL && poll <= MAX_POLL);
+
+  /* Allow up to 8 sources using the same short interval to not be limited
+     by the separation */
+  separation = UTI_Log2ToDouble(poll - 3);
+
+  return CLAMP(MIN_SAMPLING_SEPARATION, separation, MAX_SAMPLING_SEPARATION);
+}
+
+/* ================================================== */
+/* Timeout handler for closing the client socket when no acceptable
+   reply can be received from the server */
+
+static void
+receive_timeout(void *arg)
+{
+  NCR_Instance inst = (NCR_Instance)arg;
+
+  DEBUG_LOG("Receive timeout for %s", UTI_IPSockAddrToString(&inst->remote_addr));
+
+  inst->rx_timeout_id = 0;
+  close_client_socket(inst);
+}
+
+/* ================================================== */
+
+static int
+add_ext_exp1(NTP_Packet *message, NTP_PacketInfo *info, struct timespec *rx,
+             double root_delay, double root_dispersion)
+{
+  struct timespec mono_rx;
+  NTP_ExtFieldExp1 exp1;
+  NTP_int64 ts_fuzz;
+
+  memset(&exp1, 0, sizeof (exp1));
+  exp1.magic = htonl(NTP_EF_EXP1_MAGIC);
+
+  if (info->mode != MODE_CLIENT) {
+    exp1.root_delay = UTI_DoubleToNtp32f28(root_delay);
+    exp1.root_dispersion = UTI_DoubleToNtp32f28(root_dispersion);
+    if (rx)
+      UTI_AddDoubleToTimespec(rx, server_mono_offset, &mono_rx);
+    else
+      UTI_ZeroTimespec(&mono_rx);
+    UTI_GetNtp64Fuzz(&ts_fuzz, message->precision);
+    UTI_TimespecToNtp64(&mono_rx, &exp1.mono_receive_ts, &ts_fuzz);
+    exp1.mono_epoch = htonl(server_mono_epoch);
+  }
+
+  if (!NEF_AddField(message, info, NTP_EF_EXP1, &exp1, sizeof (exp1))) {
+    DEBUG_LOG("Could not add EF");
+    return 0;
+  }
+
+  info->ext_field_flags |= NTP_EF_FLAG_EXP1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+transmit_packet(NTP_Mode my_mode, /* The mode this machine wants to be */
+                int interleaved, /* Flag enabling interleaved mode */
+                int my_poll, /* The log2 of the local poll interval */
+                int version, /* The NTP version to be set in the packet */
+                uint32_t kod, /* KoD code - 0 disabled */
+                int ext_field_flags, /* Extension fields to be included in the packet */
+                NAU_Instance auth, /* The authentication to be used for the packet */
+                NTP_int64 *remote_ntp_rx, /* The receive timestamp from received packet */
+                NTP_int64 *remote_ntp_tx, /* The transmit timestamp from received packet */
+                NTP_Local_Timestamp *local_rx, /* The RX time of the received packet */
+                NTP_Local_Timestamp *local_tx, /* The TX time of the previous packet
+                                                  RESULT : TX time of this packet */
+                NTP_int64 *local_ntp_rx, /* The receive timestamp from the previous packet
+                                            RESULT : receive timestamp from this packet */
+                NTP_int64 *local_ntp_tx, /* The transmit timestamp from the previous packet
+                                            RESULT : transmit timestamp from this packet */
+                NTP_Remote_Address *where_to, /* Where to address the reponse to */
+                NTP_Local_Address *from,      /* From what address to send it */
+                NTP_Packet *request,          /* The received packet if responding */
+                NTP_PacketInfo *request_info  /* and its info */
+                )
+{
+  NTP_PacketInfo info;
+  NTP_Packet message;
+  struct timespec local_receive, local_transmit;
+  double smooth_offset, local_transmit_err;
+  int ret, precision;
+  NTP_int64 ts_fuzz;
+
+  /* Parameters read from reference module */
+  int are_we_synchronised, our_stratum, smooth_time;
+  NTP_Leap leap_status;
+  uint32_t our_ref_id;
+  struct timespec our_ref_time;
+  double our_root_delay, our_root_dispersion;
+
+  assert(auth || (request && request_info));
+
+  /* Don't reply with version higher than ours */
+  if (version > NTP_VERSION) {
+    version = NTP_VERSION;
+  }
+
+  /* Check if the packet can be formed in the interleaved mode */
+  if (interleaved && (!remote_ntp_rx || !local_tx || UTI_IsZeroTimespec(&local_tx->ts)))
+    interleaved = 0;
+
+  smooth_time = 0;
+  smooth_offset = 0.0;
+
+  /* Get an initial transmit timestamp.  A more accurate timestamp will be
+     taken later in this function. */
+  SCH_GetLastEventTime(&local_transmit, NULL, NULL);
+
+  if (my_mode == MODE_CLIENT) {
+    /* Don't reveal local time or state of the clock in client packets */
+    precision = 32;
+    leap_status = our_stratum = our_ref_id = 0;
+    our_root_delay = our_root_dispersion = 0.0;
+    UTI_ZeroTimespec(&our_ref_time);
+  } else {
+    REF_GetReferenceParams(&local_transmit,
+                           &are_we_synchronised, &leap_status,
+                           &our_stratum,
+                           &our_ref_id, &our_ref_time,
+                           &our_root_delay, &our_root_dispersion);
+
+    /* Get current smoothing offset when sending packet to a client */
+    if (SMT_IsEnabled() && (my_mode == MODE_SERVER || my_mode == MODE_BROADCAST)) {
+      smooth_offset = SMT_GetOffset(&local_transmit);
+      smooth_time = fabs(smooth_offset) > LCL_GetSysPrecisionAsQuantum();
+
+      /* Suppress leap second when smoothing and slew mode are enabled */
+      if (REF_GetLeapMode() == REF_LeapModeSlew &&
+          (leap_status == LEAP_InsertSecond || leap_status == LEAP_DeleteSecond))
+        leap_status = LEAP_Normal;
+    }
+
+    precision = LCL_GetSysPrecisionAsLog();
+  }
+
+  if (smooth_time && !UTI_IsZeroTimespec(&local_rx->ts)) {
+    our_ref_id = NTP_REFID_SMOOTH;
+    UTI_AddDoubleToTimespec(&our_ref_time, smooth_offset, &our_ref_time);
+    UTI_AddDoubleToTimespec(&local_rx->ts, smooth_offset, &local_receive);
+  } else {
+    local_receive = local_rx->ts;
+  }
+
+  if (kod != 0) {
+    leap_status = LEAP_Unsynchronised;
+    our_stratum = NTP_INVALID_STRATUM;
+    our_ref_id = kod;
+  }
+
+  /* Generate transmit packet */
+  message.lvm = NTP_LVM(leap_status, version, my_mode);
+  /* Stratum 16 and larger are invalid */
+  if (our_stratum < NTP_MAX_STRATUM) {
+    message.stratum = our_stratum;
+  } else {
+    message.stratum = NTP_INVALID_STRATUM;
+  }
+ 
+  message.poll = my_poll;
+  message.precision = precision;
+  message.root_delay = UTI_DoubleToNtp32(our_root_delay);
+  message.root_dispersion = UTI_DoubleToNtp32(our_root_dispersion);
+  message.reference_id = htonl(our_ref_id);
+
+  /* Now fill in timestamps */
+
+  UTI_TimespecToNtp64(&our_ref_time, &message.reference_ts, NULL);
+
+  /* Don't reveal timestamps which are not necessary for the protocol */
+
+  if (my_mode != MODE_CLIENT || interleaved) {
+    /* Originate - this comes from the last packet the source sent us */
+    message.originate_ts = interleaved ? *remote_ntp_rx : *remote_ntp_tx;
+
+    do {
+      /* Prepare random bits which will be added to the receive timestamp */
+      UTI_GetNtp64Fuzz(&ts_fuzz, precision);
+
+      /* Receive - this is when we received the last packet from the source.
+         This timestamp will have been adjusted so that it will now look to
+         the source like we have been running on our latest estimate of
+         frequency all along */
+      UTI_TimespecToNtp64(&local_receive, &message.receive_ts, &ts_fuzz);
+
+      /* Do not send a packet with a non-zero receive timestamp equal to the
+         originate timestamp or previous receive timestamp */
+    } while (!UTI_IsZeroNtp64(&message.receive_ts) &&
+             UTI_IsEqualAnyNtp64(&message.receive_ts, &message.originate_ts,
+                                 local_ntp_rx, NULL));
+  } else {
+    UTI_ZeroNtp64(&message.originate_ts);
+    UTI_ZeroNtp64(&message.receive_ts);
+  }
+
+  if (!parse_packet(&message, NTP_HEADER_LENGTH, &info))
+    return 0;
+
+  if (ext_field_flags) {
+    if (ext_field_flags & NTP_EF_FLAG_EXP1) {
+      if (!add_ext_exp1(&message, &info, smooth_time ? NULL : &local_receive,
+                        our_root_delay, our_root_dispersion))
+        return 0;
+    }
+  }
+
+  do {
+    /* Prepare random bits which will be added to the transmit timestamp */
+    UTI_GetNtp64Fuzz(&ts_fuzz, precision);
+
+    /* Get a more accurate transmit timestamp if it needs to be saved in the
+       packet (i.e. in the server, symmetric, and broadcast basic modes) */
+    if (!interleaved && precision < 32) {
+      LCL_ReadCookedTime(&local_transmit, &local_transmit_err);
+      if (smooth_time)
+        UTI_AddDoubleToTimespec(&local_transmit, smooth_offset, &local_transmit);
+    }
+
+    UTI_TimespecToNtp64(interleaved ? &local_tx->ts : &local_transmit,
+                        &message.transmit_ts, &ts_fuzz);
+
+    /* Do not send a packet with a non-zero transmit timestamp which is
+       equal to any of the following timestamps:
+       - receive (to allow reliable detection of the interleaved mode)
+       - originate (to prevent the packet from being its own valid response
+                    in the symmetric mode)
+       - previous transmit (to invalidate responses to the previous packet)
+       (the precision must be at least -30 to prevent an infinite loop!) */
+  } while (!UTI_IsZeroNtp64(&message.transmit_ts) &&
+           UTI_IsEqualAnyNtp64(&message.transmit_ts, &message.receive_ts,
+                               &message.originate_ts, local_ntp_tx));
+
+  /* Encode in server timestamps a flag indicating RX timestamp to avoid
+     saving all RX timestamps for detection of interleaved requests */
+  if (my_mode == MODE_SERVER || my_mode == MODE_PASSIVE) {
+    message.receive_ts.lo |= htonl(1);
+    message.transmit_ts.lo &= ~htonl(1);
+  }
+
+  /* Generate the authentication data */
+  if (auth) {
+    if (!NAU_GenerateRequestAuth(auth, &message, &info)) {
+      DEBUG_LOG("Could not generate request auth");
+      return 0;
+    }
+  } else {
+    if (!NAU_GenerateResponseAuth(request, request_info, &message, &info,
+                                  where_to, from, kod)) {
+      DEBUG_LOG("Could not generate response auth");
+      return 0;
+    }
+  }
+
+  if (request_info && request_info->length < info.length) {
+    DEBUG_LOG("Response longer than request req_len=%d res_len=%d",
+              request_info->length, info.length);
+    return 0;
+  }
+
+  /* If the transmit timestamp will be saved, get an even more
+     accurate daemon timestamp closer to the transmission */
+  if (local_tx)
+    LCL_ReadCookedTime(&local_transmit, &local_transmit_err);
+
+  ret = NIO_SendPacket(&message, where_to, from, info.length, local_tx != NULL);
+
+  if (local_tx) {
+    if (smooth_time)
+      UTI_AddDoubleToTimespec(&local_transmit, smooth_offset, &local_transmit);
+    local_tx->ts = local_transmit;
+    local_tx->err = local_transmit_err;
+    local_tx->source = NTP_TS_DAEMON;
+  }
+
+  if (local_ntp_rx)
+    *local_ntp_rx = message.receive_ts;
+  if (local_ntp_tx)
+    *local_ntp_tx = message.transmit_ts;
+
+  return ret;
+}
+
+/* ================================================== */
+/* Timeout handler for transmitting to a source. */
+
+static void
+transmit_timeout(void *arg)
+{
+  NCR_Instance inst = (NCR_Instance) arg;
+  NTP_Local_Address local_addr;
+  int interleaved, initial, sent;
+
+  inst->tx_timeout_id = 0;
+
+  switch (inst->opmode) {
+    case MD_BURST_WAS_ONLINE:
+      /* With online burst switch to online before last packet */
+      if (inst->burst_total_samples_to_go <= 1)
+        inst->opmode = MD_ONLINE;
+      break;
+    case MD_BURST_WAS_OFFLINE:
+      if (inst->burst_total_samples_to_go <= 0)
+        take_offline(inst);
+      break;
+    case MD_ONLINE:
+      /* Start a new burst if the burst option is enabled and the average
+         polling interval including the burst will not fall below the
+         minimum polling interval */
+      if (inst->auto_burst && inst->local_poll > inst->minpoll)
+        NCR_InitiateSampleBurst(inst, BURST_GOOD_SAMPLES,
+                                MIN(1 << (inst->local_poll - inst->minpoll),
+                                    MAX_BURST_TOTAL_SAMPLES));
+      break;
+    default:
+      break;
+  }
+
+  if (inst->opmode == MD_OFFLINE) {
+    return;
+  }
+
+  DEBUG_LOG("Transmit timeout for %s", UTI_IPSockAddrToString(&inst->remote_addr));
+
+  /* Prepare authentication */
+  if (!NAU_PrepareRequestAuth(inst->auth)) {
+    if (inst->burst_total_samples_to_go > 0)
+      inst->burst_total_samples_to_go--;
+    adjust_poll(inst, 0.25);
+    SRC_UpdateReachability(inst->source, 0);
+    restart_timeout(inst, get_transmit_delay(inst, 1, 0.0));
+    return;
+  }
+
+  /* Open new client socket */
+  if (inst->mode == MODE_CLIENT) {
+    close_client_socket(inst);
+    assert(inst->local_addr.sock_fd == INVALID_SOCK_FD);
+    inst->local_addr.sock_fd = NIO_OpenClientSocket(&inst->remote_addr);
+  }
+
+  /* Don't require the packet to be sent from the same address as before */
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = inst->local_addr.sock_fd;
+
+  /* In symmetric mode, don't send a packet in interleaved mode unless it
+     is the first response to the last valid request received from the peer
+     and there was just one response to the previous valid request.  This
+     prevents the peer from matching the transmit timestamp with an older
+     response if it can't detect missed responses.  In client mode, which has
+     at most one response per request, check how many responses are missing to
+     prevent the server from responding with a very old transmit timestamp. */
+  interleaved = inst->interleaved &&
+                ((inst->mode == MODE_CLIENT &&
+                  inst->tx_count < MAX_CLIENT_INTERLEAVED_TX) ||
+                 (inst->mode == MODE_ACTIVE &&
+                  inst->prev_tx_count == 1 && inst->tx_count == 0));
+
+  /* In symmetric mode, if no valid response was received since the previous
+     transmission, respond to the last received packet even if it failed some
+     specific NTP tests.  This is necessary for starting and restarting the
+     protocol, e.g. when a packet was lost. */
+  initial = inst->mode == MODE_ACTIVE && !inst->valid_rx &&
+            !UTI_IsZeroNtp64(&inst->init_remote_ntp_tx);
+
+  /* Prepare for the response */
+  inst->valid_rx = 0;
+  inst->updated_init_timestamps = 0;
+  if (initial)
+    inst->valid_timestamps = 0;
+
+  /* Check whether we need to 'warm up' the link to the other end by
+     sending an NTP exchange to ensure both ends' ARP caches are
+     primed or whether we need to send two packets first to ensure a
+     server in the interleaved mode has a fresh timestamp for us. */
+  if (inst->presend_minpoll <= inst->local_poll && !inst->presend_done &&
+      !inst->burst_total_samples_to_go) {
+    inst->presend_done = interleaved ? 2 : 1;
+  } else if (inst->presend_done > 0) {
+    inst->presend_done--;
+  }
+
+  /* Send the request (which may also be a response in the symmetric mode) */
+  sent = transmit_packet(inst->mode, interleaved, inst->local_poll, inst->version, 0,
+                         inst->ext_field_flags, inst->auth,
+                         initial ? NULL : &inst->remote_ntp_rx,
+                         initial ? &inst->init_remote_ntp_tx : &inst->remote_ntp_tx,
+                         initial ? &inst->init_local_rx : &inst->local_rx,
+                         &inst->local_tx, &inst->local_ntp_rx, &inst->local_ntp_tx,
+                         &inst->remote_addr, &local_addr, NULL, NULL);
+
+  ++inst->tx_count;
+  if (sent)
+    inst->report.total_tx_count++;
+
+  /* If the source loses connectivity and our packets are still being sent,
+     back off the sampling rate to reduce the network traffic.  If it's the
+     source to which we are currently locked, back off slowly. */
+
+  if (inst->tx_count >= 2) {
+    /* Implies we have missed at least one transmission */
+
+    if (sent) {
+      adjust_poll(inst, SRC_IsSyncPeer(inst->source) ? 0.1 : 0.25);
+    }
+
+    SRC_UpdateReachability(inst->source, 0);
+
+    /* Count missing samples for the sample filter */
+    process_sample(inst, NULL);
+  }
+
+  /* With auto_offline take the source offline if sending failed */
+  if (!sent && inst->auto_offline)
+    NCR_SetConnectivity(inst, SRC_OFFLINE);
+
+  switch (inst->opmode) {
+    case MD_BURST_WAS_ONLINE:
+      /* When not reachable, don't stop online burst until sending succeeds */
+      if (!sent && !SRC_IsReachable(inst->source))
+        break;
+      /* Fall through */
+    case MD_BURST_WAS_OFFLINE:
+      --inst->burst_total_samples_to_go;
+      break;
+    case MD_OFFLINE:
+      return;
+    default:
+      break;
+  }
+
+  /* Restart timer for this message */
+  restart_timeout(inst, get_transmit_delay(inst, 1, 0.0));
+
+  /* If a client packet was just sent, schedule a timeout to close the socket
+     at the time when all server replies would fail the delay test, so the
+     socket is not open for longer than necessary */
+  if (inst->mode == MODE_CLIENT)
+    inst->rx_timeout_id = SCH_AddTimeoutByDelay(inst->max_delay + MAX_SERVER_INTERVAL,
+                                                receive_timeout, (void *)inst);
+}
+
+/* ================================================== */
+
+static int
+is_zero_data(unsigned char *data, int length)
+{
+  int i;
+
+  for (i = 0; i < length; i++)
+    if (data[i] != 0)
+      return 0;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_packet(NTP_Packet *packet, int length, NTP_PacketInfo *info)
+{
+  int parsed, remainder, ef_length, ef_type, ef_body_length;
+  unsigned char *data;
+  void *ef_body;
+
+  if (length < NTP_HEADER_LENGTH || length % 4U != 0) {
+    DEBUG_LOG("NTP packet has invalid length %d", length);
+    return 0;
+  }
+
+  info->length = length;
+  info->version = NTP_LVM_TO_VERSION(packet->lvm);
+  info->mode = NTP_LVM_TO_MODE(packet->lvm);
+  info->ext_fields = 0;
+  info->ext_field_flags = 0;
+  info->auth.mode = NTP_AUTH_NONE;
+
+  if (info->version < NTP_MIN_COMPAT_VERSION || info->version > NTP_MAX_COMPAT_VERSION) {
+    DEBUG_LOG("NTP packet has invalid version %d", info->version);
+    return 0;
+  }
+
+  data = (void *)packet;
+  parsed = NTP_HEADER_LENGTH;
+  remainder = info->length - parsed;
+
+  /* Check if this is a plain NTP packet with no extension fields or MAC */
+  if (remainder <= 0)
+    return 1;
+
+  assert(remainder % 4 == 0);
+
+  /* In NTPv3 and older packets don't have extension fields.  Anything after
+     the header is assumed to be a MAC. */
+  if (info->version <= 3) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
+
+    /* Check if it is an MS-SNTP authenticator field or extended authenticator
+       field with zeroes as digest */
+    if (info->version == 3 && info->auth.mac.key_id != 0) {
+      if (remainder == 20 && is_zero_data(data + parsed + 4, remainder - 4))
+        info->auth.mode = NTP_AUTH_MSSNTP;
+      else if (remainder == 72 && is_zero_data(data + parsed + 8, remainder - 8))
+        info->auth.mode = NTP_AUTH_MSSNTP_EXT;
+    }
+
+    return 1;
+  }
+
+  /* Check for a crypto NAK */
+  if (remainder == 4 && ntohl(*(uint32_t *)(data + parsed)) == 0) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = 0;
+    return 1;
+  }
+
+  /* Parse the rest of the NTPv4 packet */
+
+  while (remainder > 0) {
+    /* Check if the remaining data is a MAC */
+    if (remainder >= NTP_MIN_MAC_LENGTH && remainder <= NTP_MAX_V4_MAC_LENGTH)
+      break;
+
+    /* Check if this is a valid NTPv4 extension field and skip it */
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length)) {
+      DEBUG_LOG("Invalid format");
+      return 0;
+    }
+
+    assert(ef_length > 0 && ef_length % 4 == 0);
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+      case NTP_EF_NTS_COOKIE:
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        info->auth.mode = NTP_AUTH_NTS;
+        break;
+      case NTP_EF_EXP1:
+        if (ef_body_length == sizeof (NTP_ExtFieldExp1) &&
+            ntohl(((NTP_ExtFieldExp1 *)ef_body)->magic) == NTP_EF_EXP1_MAGIC)
+          info->ext_field_flags |= NTP_EF_FLAG_EXP1;
+        break;
+      default:
+        DEBUG_LOG("Unknown extension field type=%x", (unsigned int)ef_type);
+    }
+
+    info->ext_fields++;
+    parsed += ef_length;
+    remainder = info->length - parsed;
+  }
+
+  if (remainder == 0) {
+    /* No MAC */
+    return 1;
+  } else if (remainder >= NTP_MIN_MAC_LENGTH) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
+    return 1;
+  }
+
+  DEBUG_LOG("Invalid format");
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_ratio(NCR_Instance inst, SST_Stats stats,
+                struct timespec *sample_time, double delay)
+{
+  double last_sample_ago, predicted_offset, min_delay, skew, std_dev;
+  double max_delay;
+
+  if (inst->max_delay_ratio < 1.0 ||
+      !SST_GetDelayTestData(stats, sample_time, &last_sample_ago,
+                            &predicted_offset, &min_delay, &skew, &std_dev))
+    return 1;
+
+  max_delay = min_delay * inst->max_delay_ratio +
+              last_sample_ago * (skew + LCL_GetMaxClockError());
+
+  if (delay <= max_delay)
+    return 1;
+
+  DEBUG_LOG("maxdelayratio: delay=%e max_delay=%e", delay, max_delay);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_quant(NCR_Instance inst, double delay)
+{
+  double quant;
+
+  quant = QNT_GetQuantile(inst->delay_quant, QNT_GetMinK(inst->delay_quant));
+
+  if (delay <= quant)
+    return 1;
+
+  DEBUG_LOG("maxdelayquant: delay=%e quant=%e", delay, quant);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_dev_ratio(NCR_Instance inst, SST_Stats stats,
+                      struct timespec *sample_time, double offset, double delay)
+{
+  double last_sample_ago, predicted_offset, min_delay, skew, std_dev;
+  double delta, max_delta, error_in_estimate;
+
+  if (!SST_GetDelayTestData(stats, sample_time, &last_sample_ago,
+                            &predicted_offset, &min_delay, &skew, &std_dev))
+    return 1;
+
+  /* Require that the ratio of the increase in delay from the minimum to the
+     standard deviation is less than max_delay_dev_ratio.  In the allowed
+     increase in delay include also dispersion. */
+
+  max_delta = std_dev * inst->max_delay_dev_ratio +
+              last_sample_ago * (skew + LCL_GetMaxClockError());
+  delta = (delay - min_delay) / 2.0;
+
+  if (delta <= max_delta)
+    return 1;
+
+  error_in_estimate = offset + predicted_offset;
+
+  /* Before we decide to drop the sample, make sure the difference between
+     measured offset and predicted offset is not significantly larger than
+     the increase in delay */
+  if (fabs(error_in_estimate) - delta > max_delta)
+    return 1;
+
+  DEBUG_LOG("maxdelaydevratio: error=%e delay=%e delta=%e max_delta=%e",
+            error_in_estimate, delay, delta, max_delta);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_sync_loop(NCR_Instance inst, NTP_Packet *message, NTP_Local_Address *local_addr,
+                struct timespec *local_ts)
+{
+  double our_root_delay, our_root_dispersion;
+  int are_we_synchronised, our_stratum;
+  struct timespec our_ref_time;
+  NTP_Leap leap_status;
+  uint32_t our_ref_id;
+
+  /* Check if a client or peer can be synchronised to us */
+  if (!NIO_IsServerSocketOpen() || REF_GetMode() != REF_ModeNormal)
+    return 1;
+
+  /* Check if the source indicates that it is synchronised to our address
+     (assuming it uses the same address as the one from which we send requests
+     to the source) */
+  if (message->stratum > 1 &&
+      message->reference_id == htonl(UTI_IPToRefid(&local_addr->ip_addr)))
+    return 0;
+
+  /* Compare our reference data with the source to make sure it is not us
+     (e.g. due to a misconfiguration) */
+
+  REF_GetReferenceParams(local_ts, &are_we_synchronised, &leap_status, &our_stratum,
+                         &our_ref_id, &our_ref_time, &our_root_delay, &our_root_dispersion);
+
+  if (message->stratum == our_stratum &&
+      message->reference_id == htonl(our_ref_id) &&
+      message->root_delay == UTI_DoubleToNtp32(our_root_delay) &&
+      !UTI_IsZeroNtp64(&message->reference_ts)) {
+    NTP_int64 ntp_ref_time;
+
+    UTI_TimespecToNtp64(&our_ref_time, &ntp_ref_time, NULL);
+    if (UTI_CompareNtp64(&message->reference_ts, &ntp_ref_time) == 0) {
+      DEBUG_LOG("Source %s is me", UTI_IPToString(&inst->remote_addr.ip_addr));
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_sample(NCR_Instance inst, NTP_Sample *sample)
+{
+  double estimated_offset, error_in_estimate;
+  NTP_Sample filtered_sample;
+
+  /* Accumulate the sample to the median filter if enabled and wait for
+     the configured number of samples before processing (NULL indicates
+     a missing sample) */
+  if (inst->filter) {
+    if (sample)
+      SPF_AccumulateSample(inst->filter, sample);
+
+    if (++inst->filter_count < SPF_GetMaxSamples(inst->filter))
+      return;
+
+    if (!SPF_GetFilteredSample(inst->filter, &filtered_sample))
+      return;
+
+    sample = &filtered_sample;
+    inst->filter_count = 0;
+  }
+
+  if (!sample)
+    return;
+
+  /* Get the estimated offset predicted from previous samples.  The
+     convention here is that positive means local clock FAST of
+     reference, i.e. backwards to the way that 'offset' is defined. */
+  estimated_offset = SST_PredictOffset(SRC_GetSourcestats(inst->source), &sample->time);
+
+  error_in_estimate = fabs(-sample->offset - estimated_offset);
+
+  if (inst->mono_doffset != 0.0 && fabs(inst->mono_doffset) <= MAX_MONO_DOFFSET) {
+    DEBUG_LOG("Monotonic correction offset=%.9f", inst->mono_doffset);
+    SST_CorrectOffset(SRC_GetSourcestats(inst->source), inst->mono_doffset);
+  }
+  inst->mono_doffset = 0.0;
+
+  SRC_AccumulateSample(inst->source, sample);
+  SRC_SelectSource(inst->source);
+
+  adjust_poll(inst, get_poll_adj(inst, error_in_estimate,
+                                 sample->peer_dispersion + 0.5 * sample->peer_delay));
+}
+
+/* ================================================== */
+
+static int
+process_response(NCR_Instance inst, NTP_Local_Address *local_addr,
+                 NTP_Local_Timestamp *rx_ts, NTP_Packet *message, NTP_PacketInfo *info)
+{
+  NTP_Sample sample;
+  SST_Stats stats;
+
+  int pkt_leap, pkt_version;
+  uint32_t pkt_refid;
+  double pkt_root_delay;
+  double pkt_root_dispersion;
+
+  /* The skew and estimated frequency offset relative to the remote source */
+  double skew, source_freq_lo, source_freq_hi;
+
+  /* RFC 5905 packet tests */
+  int test1, test2n, test2i, test2, test3, test5, test6, test7;
+  int interleaved_packet, valid_packet, synced_packet;
+
+  /* Additional tests */
+  int testA, testB, testC, testD;
+  int good_packet;
+
+  /* Kiss-o'-Death codes */
+  int kod_rate;
+
+  /* Extension fields */
+  int parsed, ef_length, ef_type, ef_body_length;
+  void *ef_body;
+  NTP_ExtFieldExp1 *ef_exp1;
+
+  NTP_Local_Timestamp local_receive, local_transmit;
+  double remote_interval, local_interval, response_time;
+  double delay_time, precision, mono_doffset;
+  int updated_timestamps;
+
+  /* ==================== */
+
+  stats = SRC_GetSourcestats(inst->source);
+
+  ef_exp1 = NULL;
+
+  /* Find requested non-authentication extension fields */
+  if (inst->ext_field_flags & info->ext_field_flags) {
+    for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+      if (!NEF_ParseField(message, info->length, parsed,
+                          &ef_length, &ef_type, &ef_body, &ef_body_length))
+        break;
+
+      switch (ef_type) {
+        case NTP_EF_EXP1:
+          if (inst->ext_field_flags & NTP_EF_FLAG_EXP1 &&
+              ef_body_length == sizeof (*ef_exp1) &&
+              ntohl(((NTP_ExtFieldExp1 *)ef_body)->magic) == NTP_EF_EXP1_MAGIC)
+            ef_exp1 = ef_body;
+          break;
+      }
+    }
+  }
+
+  pkt_leap = NTP_LVM_TO_LEAP(message->lvm);
+  pkt_version = NTP_LVM_TO_VERSION(message->lvm);
+  pkt_refid = ntohl(message->reference_id);
+  if (ef_exp1) {
+    pkt_root_delay = UTI_Ntp32f28ToDouble(ef_exp1->root_delay);
+    pkt_root_dispersion = UTI_Ntp32f28ToDouble(ef_exp1->root_dispersion);
+  } else {
+    pkt_root_delay = UTI_Ntp32ToDouble(message->root_delay);
+    pkt_root_dispersion = UTI_Ntp32ToDouble(message->root_dispersion);
+  }
+
+  /* Check if the packet is valid per RFC 5905, section 8.
+     The test values are 1 when passed and 0 when failed. */
+  
+  /* Test 1 checks for duplicate packet */
+  test1 = UTI_CompareNtp64(&message->receive_ts, &inst->remote_ntp_rx) ||
+          UTI_CompareNtp64(&message->transmit_ts, &inst->remote_ntp_tx);
+
+  /* Test 2 checks for bogus packet in the basic and interleaved modes.  This
+     ensures the source is responding to the latest packet we sent to it. */
+  test2n = !UTI_CompareNtp64(&message->originate_ts, &inst->local_ntp_tx);
+  test2i = inst->interleaved &&
+           !UTI_CompareNtp64(&message->originate_ts, &inst->local_ntp_rx);
+  test2 = test2n || test2i;
+  interleaved_packet = !test2n && test2i;
+  
+  /* Test 3 checks for invalid timestamps.  This can happen when the
+     association if not properly 'up'. */
+  test3 = !UTI_IsZeroNtp64(&message->originate_ts) &&
+          !UTI_IsZeroNtp64(&message->receive_ts) &&
+          !UTI_IsZeroNtp64(&message->transmit_ts);
+
+  /* Test 4 would check for denied access.  It would always pass as this
+     function is called only for known sources. */
+
+  /* Test 5 checks for authentication failure */
+  test5 = NAU_CheckResponseAuth(inst->auth, message, info);
+
+  /* Test 6 checks for unsynchronised server */
+  test6 = pkt_leap != LEAP_Unsynchronised &&
+          message->stratum < NTP_MAX_STRATUM &&
+          message->stratum != NTP_INVALID_STRATUM; 
+
+  /* Test 7 checks for bad data.  The root distance must be smaller than a
+     defined maximum. */
+  test7 = pkt_root_delay / 2.0 + pkt_root_dispersion < NTP_MAX_DISPERSION;
+
+  /* The packet is considered valid if the tests 1-5 passed.  The timestamps
+     can be used for synchronisation if the tests 6 and 7 passed too. */
+  valid_packet = test1 && test2 && test3 && test5;
+  synced_packet = valid_packet && test6 && test7;
+
+  /* Check for Kiss-o'-Death codes */
+  kod_rate = 0;
+  if (test1 && test2 && test5 && pkt_leap == LEAP_Unsynchronised &&
+      message->stratum == NTP_INVALID_STRATUM) {
+    if (pkt_refid == KOD_RATE)
+      kod_rate = 1;
+  }
+
+  if (synced_packet && (!interleaved_packet || inst->valid_timestamps)) {
+    /* These are the timespec equivalents of the remote and local epochs */
+    struct timespec remote_receive, remote_transmit, remote_request_receive;
+    struct timespec local_average, remote_average, prev_remote_transmit;
+    double prev_remote_poll_interval, root_delay, root_dispersion;
+
+    /* If the remote monotonic timestamps are available and are from the same
+       epoch, calculate the change in the offset between the monotonic and
+       real-time clocks, i.e. separate the source's time corrections from
+       frequency corrections.  The offset is accumulated between measurements.
+       It will correct old measurements kept in sourcestats before accumulating
+       the new sample.  In the interleaved mode, cancel the correction out in
+       remote timestamps of the previous request and response, which were
+       captured before the source accumulated the new time corrections. */
+    if (ef_exp1 && inst->remote_mono_epoch == ntohl(ef_exp1->mono_epoch) &&
+        !UTI_IsZeroNtp64(&ef_exp1->mono_receive_ts) &&
+        !UTI_IsZeroNtp64(&inst->remote_ntp_monorx)) {
+      mono_doffset =
+          UTI_DiffNtp64ToDouble(&ef_exp1->mono_receive_ts, &inst->remote_ntp_monorx) -
+          UTI_DiffNtp64ToDouble(&message->receive_ts, &inst->remote_ntp_rx);
+      if (fabs(mono_doffset) > MAX_MONO_DOFFSET)
+        mono_doffset = 0.0;
+    } else {
+      mono_doffset = 0.0;
+    }
+
+    /* Select remote and local timestamps for the new sample */
+    if (interleaved_packet) {
+      /* Prefer previous local TX and remote RX timestamps if it will make
+         the intervals significantly shorter in order to improve the accuracy
+         of the measured delay */
+      if (!UTI_IsZeroTimespec(&inst->prev_local_tx.ts) &&
+          MAX_INTERLEAVED_L2L_RATIO *
+            UTI_DiffTimespecsToDouble(&inst->local_tx.ts, &inst->local_rx.ts) >
+          UTI_DiffTimespecsToDouble(&inst->local_rx.ts, &inst->prev_local_tx.ts)) {
+        UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &remote_receive);
+        UTI_AddDoubleToTimespec(&remote_receive, -mono_doffset, &remote_receive);
+        remote_request_receive = remote_receive;
+        local_transmit = inst->prev_local_tx;
+        root_delay = inst->remote_root_delay;
+        root_dispersion = inst->remote_root_dispersion;
+      } else {
+        UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
+        UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &remote_request_receive);
+        local_transmit = inst->local_tx;
+        root_delay = MAX(pkt_root_delay, inst->remote_root_delay);
+        root_dispersion = MAX(pkt_root_dispersion, inst->remote_root_dispersion);
+      }
+      UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
+      UTI_AddDoubleToTimespec(&remote_transmit, -mono_doffset, &remote_transmit);
+      UTI_Ntp64ToTimespec(&inst->remote_ntp_tx, &prev_remote_transmit);
+      local_receive = inst->local_rx;
+    } else {
+      UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
+      UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
+      UTI_ZeroTimespec(&prev_remote_transmit);
+      remote_request_receive = remote_receive;
+      local_receive = *rx_ts;
+      local_transmit = inst->local_tx;
+      root_delay = pkt_root_delay;
+      root_dispersion = pkt_root_dispersion;
+    }
+
+    /* Calculate intervals between remote and local timestamps */
+    UTI_AverageDiffTimespecs(&remote_receive, &remote_transmit,
+                             &remote_average, &remote_interval);
+    UTI_AverageDiffTimespecs(&local_transmit.ts, &local_receive.ts,
+                             &local_average, &local_interval);
+    response_time = fabs(UTI_DiffTimespecsToDouble(&remote_transmit,
+                                                   &remote_request_receive));
+
+    precision = LCL_GetSysPrecisionAsQuantum() + UTI_Log2ToDouble(message->precision);
+
+    /* Calculate delay */
+    sample.peer_delay = fabs(local_interval - remote_interval);
+    if (sample.peer_delay < precision)
+      sample.peer_delay = precision;
+    
+    /* Calculate offset.  Following the NTP definition, this is negative
+       if we are fast of the remote source. */
+    sample.offset = UTI_DiffTimespecsToDouble(&remote_average, &local_average);
+
+    /* Apply configured correction */
+    sample.offset += inst->offset_correction;
+
+    /* We treat the time of the sample as being midway through the local
+       measurement period.  An analysis assuming constant relative
+       frequency and zero network delay shows this is the only possible
+       choice to estimate the frequency difference correctly for every
+       sample pair. */
+    sample.time = local_average;
+    
+    SST_GetFrequencyRange(stats, &source_freq_lo, &source_freq_hi);
+
+    /* Calculate skew */
+    skew = (source_freq_hi - source_freq_lo) / 2.0;
+    
+    /* and then calculate peer dispersion and the rest of the sample */
+    sample.peer_dispersion = MAX(precision, MAX(local_transmit.err, local_receive.err)) +
+                             skew * fabs(local_interval);
+    sample.root_delay = root_delay + sample.peer_delay;
+    sample.root_dispersion = root_dispersion + sample.peer_dispersion;
+    
+    /* If the source is an active peer, this is the minimum assumed interval
+       between previous two transmissions (if not constrained by minpoll) */
+    prev_remote_poll_interval = UTI_Log2ToDouble(MIN(inst->remote_poll,
+                                                     inst->prev_local_poll));
+
+    /* Additional tests required to pass before accumulating the sample */
+
+    /* Test A requires that the minimum estimate of the peer delay is not
+       larger than the configured maximum, in both client modes that the server
+       processing time is sane, in interleaved client/server mode that the
+       previous response was not in basic mode (which prevents using timestamps
+       that minimise delay error), and in interleaved symmetric mode that the
+       measured delay and intervals between remote timestamps don't indicate
+       a missed response */
+    testA = sample.peer_delay - sample.peer_dispersion <= inst->max_delay &&
+            precision <= inst->max_delay &&
+            !(inst->mode == MODE_CLIENT && response_time > MAX_SERVER_INTERVAL) &&
+            !(inst->mode == MODE_CLIENT && interleaved_packet &&
+              UTI_IsZeroTimespec(&inst->prev_local_tx.ts) &&
+              UTI_CompareTimespecs(&local_transmit.ts, &inst->local_tx.ts) == 0) &&
+            !(inst->mode == MODE_ACTIVE && interleaved_packet &&
+              (sample.peer_delay > 0.5 * prev_remote_poll_interval ||
+               UTI_CompareNtp64(&message->receive_ts, &message->transmit_ts) <= 0 ||
+               (inst->remote_poll <= inst->prev_local_poll &&
+                UTI_DiffTimespecsToDouble(&remote_transmit, &prev_remote_transmit) >
+                  1.5 * prev_remote_poll_interval)));
+
+    /* Test B requires in client mode that the ratio of the round trip delay
+       to the minimum one currently in the stats data register is less than an
+       administrator-defined value */
+    testB = check_delay_ratio(inst, stats, &sample.time, sample.peer_delay);
+
+    /* Test C either requires that the delay is less than an estimate of an
+       administrator-defined quantile, or (if the quantile is not specified)
+       it requires that the ratio of the increase in delay from the minimum
+       one in the stats data register to the standard deviation of the offsets
+       in the register is less than an administrator-defined value or the
+       difference between measured offset and predicted offset is larger than
+       the increase in delay */
+    if (inst->delay_quant)
+      testC = check_delay_quant(inst, sample.peer_delay);
+    else
+      testC = check_delay_dev_ratio(inst, stats, &sample.time, sample.offset,
+                                    sample.peer_delay);
+
+    /* Test D requires that the source is not synchronised to us and is not us
+       to prevent a synchronisation loop */
+    testD = check_sync_loop(inst, message, local_addr, &rx_ts->ts);
+  } else {
+    remote_interval = local_interval = response_time = 0.0;
+    sample.offset = sample.peer_delay = sample.peer_dispersion = 0.0;
+    sample.root_delay = sample.root_dispersion = 0.0;
+    sample.time = rx_ts->ts;
+    mono_doffset = 0.0;
+    local_receive = *rx_ts;
+    local_transmit = inst->local_tx;
+    testA = testB = testC = testD = 0;
+  }
+  
+  /* The packet is considered good for synchronisation if
+     the additional tests passed */
+  good_packet = testA && testB && testC && testD;
+
+  /* Update the NTP timestamps.  If it's a valid packet from a synchronised
+     source, the timestamps may be used later when processing a packet in the
+     interleaved mode.  Protect the timestamps against replay attacks in client
+     mode, and also in symmetric mode as long as the peers use the same polling
+     interval and never start with clocks in future or very distant past.
+     The authentication test (test5) is required to prevent DoS attacks using
+     unauthenticated packets on authenticated symmetric associations. */
+  if ((inst->mode == MODE_CLIENT && valid_packet && !inst->valid_rx) ||
+      (inst->mode == MODE_ACTIVE && valid_packet &&
+       (!inst->valid_rx ||
+        UTI_CompareNtp64(&inst->remote_ntp_tx, &message->transmit_ts) < 0))) {
+    inst->remote_ntp_rx = message->receive_ts;
+    inst->remote_ntp_tx = message->transmit_ts;
+    inst->local_rx = *rx_ts;
+    inst->valid_timestamps = synced_packet;
+
+    UTI_ZeroNtp64(&inst->init_remote_ntp_tx);
+    zero_local_timestamp(&inst->init_local_rx);
+    inst->updated_init_timestamps = 0;
+    updated_timestamps = 2;
+
+    /* If available, update the monotonic timestamp and accumulate the offset.
+       This needs to be done here to not lose changes in remote_ntp_rx in
+       symmetric mode when there are multiple responses per request. */
+    if (ef_exp1 && !UTI_IsZeroNtp64(&ef_exp1->mono_receive_ts)) {
+      inst->remote_mono_epoch = ntohl(ef_exp1->mono_epoch);
+      inst->remote_ntp_monorx = ef_exp1->mono_receive_ts;
+      inst->mono_doffset += mono_doffset;
+    } else {
+      inst->remote_mono_epoch = 0;
+      UTI_ZeroNtp64(&inst->remote_ntp_monorx);
+      inst->mono_doffset = 0.0;
+    }
+
+    /* Don't use the same set of timestamps for the next sample */
+    if (interleaved_packet)
+      inst->prev_local_tx = inst->local_tx;
+    else
+      zero_local_timestamp(&inst->prev_local_tx);
+  } else if (inst->mode == MODE_ACTIVE &&
+             test1 && !UTI_IsZeroNtp64(&message->transmit_ts) && test5 &&
+             (!inst->updated_init_timestamps ||
+              UTI_CompareNtp64(&inst->init_remote_ntp_tx, &message->transmit_ts) < 0)) {
+    inst->init_remote_ntp_tx = message->transmit_ts;
+    inst->init_local_rx = *rx_ts;
+    inst->updated_init_timestamps = 1;
+    updated_timestamps = 1;
+  } else {
+    updated_timestamps = 0;
+  }
+
+  /* Accept at most one response per request.  The NTP specification recommends
+     resetting local_ntp_tx to make the following packets fail test2 or test3,
+     but that would not allow the code above to make multiple updates of the
+     timestamps in symmetric mode.  Also, ignore presend responses. */
+  if (inst->valid_rx) {
+    test2 = test3 = 0;
+    valid_packet = synced_packet = good_packet = 0;
+  } else if (valid_packet) {
+    if (inst->presend_done) {
+      testA = 0;
+      good_packet = 0;
+    }
+    inst->valid_rx = 1;
+  }
+
+  if ((unsigned int)local_receive.source >= sizeof (tss_chars) ||
+      (unsigned int)local_transmit.source >= sizeof (tss_chars))
+    assert(0);
+
+  DEBUG_LOG("NTP packet lvm=%o stratum=%d poll=%d prec=%d root_delay=%.9f root_disp=%.9f refid=%"PRIx32" [%s]",
+            message->lvm, message->stratum, message->poll, message->precision,
+            pkt_root_delay, pkt_root_dispersion, pkt_refid,
+            message->stratum == NTP_INVALID_STRATUM || message->stratum == 1 ?
+              UTI_RefidToString(pkt_refid) : "");
+  DEBUG_LOG("reference=%s origin=%s receive=%s transmit=%s",
+            UTI_Ntp64ToString(&message->reference_ts),
+            UTI_Ntp64ToString(&message->originate_ts),
+            UTI_Ntp64ToString(&message->receive_ts),
+            UTI_Ntp64ToString(&message->transmit_ts));
+  DEBUG_LOG("offset=%.9f delay=%.9f dispersion=%f root_delay=%f root_dispersion=%f",
+            sample.offset, sample.peer_delay, sample.peer_dispersion,
+            sample.root_delay, sample.root_dispersion);
+  DEBUG_LOG("remote_interval=%.9f local_interval=%.9f response_time=%.9f mono_doffset=%.9f txs=%c rxs=%c",
+            remote_interval, local_interval, response_time, mono_doffset,
+            tss_chars[local_transmit.source], tss_chars[local_receive.source]);
+  DEBUG_LOG("test123=%d%d%d test567=%d%d%d testABCD=%d%d%d%d kod_rate=%d interleaved=%d"
+            " presend=%d valid=%d good=%d updated=%d",
+            test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
+            kod_rate, interleaved_packet, inst->presend_done, valid_packet, good_packet,
+            updated_timestamps);
+
+  if (valid_packet) {
+    inst->remote_poll = message->poll;
+    inst->remote_stratum = message->stratum != NTP_INVALID_STRATUM ?
+                           MIN(message->stratum, NTP_MAX_STRATUM) : NTP_MAX_STRATUM;
+    inst->remote_root_delay = pkt_root_delay;
+    inst->remote_root_dispersion = pkt_root_dispersion;
+
+    inst->prev_local_poll = inst->local_poll;
+    inst->prev_tx_count = inst->tx_count;
+    inst->tx_count = 0;
+
+    SRC_UpdateReachability(inst->source, synced_packet);
+
+    if (synced_packet) {
+      if (inst->copy && inst->remote_stratum > 0) {
+        /* Assume the reference ID and stratum of the server */
+        inst->remote_stratum--;
+        SRC_SetRefid(inst->source, ntohl(message->reference_id), &inst->remote_addr.ip_addr);
+      }
+
+      SRC_UpdateStatus(inst->source, MAX(inst->remote_stratum, inst->min_stratum), pkt_leap);
+
+      if (inst->delay_quant)
+        QNT_Accumulate(inst->delay_quant, sample.peer_delay);
+    }
+
+    if (good_packet) {
+      /* Adjust the polling interval, accumulate the sample, etc. */
+      process_sample(inst, &sample);
+
+      /* If we're in burst mode, check whether the burst is completed and
+         revert to the previous mode */
+      switch (inst->opmode) {
+        case MD_BURST_WAS_ONLINE:
+        case MD_BURST_WAS_OFFLINE:
+          --inst->burst_good_samples_to_go;
+          if (inst->burst_good_samples_to_go <= 0) {
+            if (inst->opmode == MD_BURST_WAS_ONLINE)
+              inst->opmode = MD_ONLINE;
+            else
+              take_offline(inst);
+          }
+          break;
+        default:
+          break;
+      }
+    } else {
+      /* Slowly increase the polling interval if we can't get a good response */
+      adjust_poll(inst, testD ? 0.02 : 0.1);
+
+      /* Count missing samples for the sample filter */
+      process_sample(inst, NULL);
+    }
+
+    /* If in client mode, no more packets are expected to be coming from the
+       server and the socket can be closed */
+    close_client_socket(inst);
+
+    /* Update the local address and interface */
+    inst->local_addr.ip_addr = local_addr->ip_addr;
+    inst->local_addr.if_index = local_addr->if_index;
+
+    /* And now, requeue the timer */
+    if (inst->opmode != MD_OFFLINE) {
+      delay_time = get_transmit_delay(inst, 0,
+                     UTI_DiffTimespecsToDouble(&inst->local_rx.ts, &inst->local_tx.ts));
+
+      if (kod_rate) {
+        LOG(LOGS_WARN, "Received KoD RATE from %s",
+            UTI_IPToString(&inst->remote_addr.ip_addr));
+
+        /* Back off for a while and stop ongoing burst */
+        delay_time += 4 * UTI_Log2ToDouble(inst->local_poll);
+
+        if (inst->opmode == MD_BURST_WAS_OFFLINE || inst->opmode == MD_BURST_WAS_ONLINE) {
+          inst->burst_good_samples_to_go = 0;
+        }
+      }
+
+      /* Get rid of old timeout and start a new one */
+      assert(inst->tx_timeout_id);
+      restart_timeout(inst, delay_time);
+    }
+
+    /* Update the NTP report */
+    inst->report.local_addr = inst->local_addr.ip_addr;
+    inst->report.leap = pkt_leap;
+    inst->report.version = pkt_version;
+    inst->report.mode = NTP_LVM_TO_MODE(message->lvm);
+    inst->report.stratum = message->stratum;
+    inst->report.poll = message->poll;
+    inst->report.precision = message->precision;
+    inst->report.root_delay = pkt_root_delay;
+    inst->report.root_dispersion = pkt_root_dispersion;
+    inst->report.ref_id = pkt_refid;
+    UTI_Ntp64ToTimespec(&message->reference_ts, &inst->report.ref_time);
+    inst->report.offset = sample.offset;
+    inst->report.peer_delay = sample.peer_delay;
+    inst->report.peer_dispersion = sample.peer_dispersion;
+    inst->report.response_time = response_time;
+    inst->report.jitter_asymmetry = SST_GetJitterAsymmetry(stats);
+    inst->report.tests = ((((((((test1 << 1 | test2) << 1 | test3) << 1 |
+                               test5) << 1 | test6) << 1 | test7) << 1 |
+                            testA) << 1 | testB) << 1 | testC) << 1 | testD;
+    inst->report.interleaved = interleaved_packet;
+    inst->report.authenticated = NAU_IsAuthEnabled(inst->auth);
+    inst->report.tx_tss_char = tss_chars[local_transmit.source];
+    inst->report.rx_tss_char = tss_chars[local_receive.source];
+
+    inst->report.total_valid_count++;
+    if (good_packet)
+      inst->report.total_good_count++;
+  }
+
+  /* Do measurement logging */
+  if (logfileid != -1 && (log_raw_measurements || synced_packet)) {
+    LOG_FileWrite(logfileid, "%s %-15s %1c %2d %1d%1d%1d %1d%1d%1d %1d%1d%1d%d  %2d %2d %4.2f %10.3e %10.3e %10.3e %10.3e %10.3e %08"PRIX32" %1d%1c %1c %1c",
+            UTI_TimeToLogForm(sample.time.tv_sec),
+            UTI_IPToString(&inst->remote_addr.ip_addr),
+            leap_chars[pkt_leap],
+            message->stratum,
+            test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
+            inst->local_poll, message->poll,
+            inst->poll_score,
+            sample.offset, sample.peer_delay, sample.peer_dispersion,
+            pkt_root_delay, pkt_root_dispersion, pkt_refid,
+            NTP_LVM_TO_MODE(message->lvm), interleaved_packet ? 'I' : 'B',
+            tss_chars[local_transmit.source],
+            tss_chars[local_receive.source]);
+  }            
+
+  return good_packet;
+}
+
+/* ================================================== */
+/* From RFC 5905, the standard handling of received packets, depending
+   on the mode of the packet and of the source, is :
+
+   +------------------+---------------------------------------+
+   |                  |              Packet Mode              |
+   +------------------+-------+-------+-------+-------+-------+
+   | Association Mode |   1   |   2   |   3   |   4   |   5   |
+   +------------------+-------+-------+-------+-------+-------+
+   | No Association 0 | NEWPS | DSCRD | FXMIT | MANY  | NEWBC |
+   | Symm. Active   1 | PROC  | PROC  | DSCRD | DSCRD | DSCRD |
+   | Symm. Passive  2 | PROC  | ERR   | DSCRD | DSCRD | DSCRD |
+   | Client         3 | DSCRD | DSCRD | DSCRD | PROC  | DSCRD |
+   | Server         4 | DSCRD | DSCRD | DSCRD | DSCRD | DSCRD |
+   | Broadcast      5 | DSCRD | DSCRD | DSCRD | DSCRD | DSCRD |
+   | Bcast Client   6 | DSCRD | DSCRD | DSCRD | DSCRD | PROC  |
+   +------------------+-------+-------+-------+-------+-------+
+
+   Association mode 0 is implemented in NCR_ProcessRxUnknown(), other modes
+   in NCR_ProcessRxKnown().
+
+   Broadcast, manycast and ephemeral symmetric passive associations are not
+   supported yet.
+ */
+
+/* ================================================== */
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we have an ongoing protocol exchange with */
+
+int
+NCR_ProcessRxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                   NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  int proc_packet, proc_as_unknown;
+  NTP_PacketInfo info;
+
+  inst->report.total_rx_count++;
+
+  if (!parse_packet(message, length, &info))
+    return 0;
+
+  proc_packet = 0;
+  proc_as_unknown = 0;
+
+  /* Now, depending on the mode we decide what to do */
+  switch (info.mode) {
+    case MODE_ACTIVE:
+      switch (inst->mode) {
+        case MODE_ACTIVE:
+          /* Ordinary symmetric peering */
+          proc_packet = 1;
+          break;
+        case MODE_PASSIVE:
+          /* In this software this case should not arise, we don't
+             support unconfigured peers */
+          break;
+        case MODE_CLIENT:
+          /* This is where we have the remote configured as a server and he has
+             us configured as a peer, process as from an unknown source */
+          proc_as_unknown = 1;
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_PASSIVE:
+      switch (inst->mode) {
+        case MODE_ACTIVE:
+          /* This would arise if we have the remote configured as a peer and
+             he does not have us configured */
+          proc_packet = 1;
+          break;
+        case MODE_PASSIVE:
+          /* Error condition in RFC 5905 */
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_CLIENT:
+      /* If message is client mode, we just respond with a server mode
+         packet, regardless of what we think the remote machine is
+         supposed to be.  However, even though this is a configured
+         peer or server, we still implement access restrictions on
+         client mode operation.
+
+         This copes with the case for an isolated network where one
+         machine is set by eye and is used as the master, with the
+         other machines pointed at it.  If the master goes down, we
+         want to be able to reset its time at startup by relying on
+         one of the secondaries to flywheel it. The behaviour coded here
+         is required in the secondaries to make this possible. */
+
+      proc_as_unknown = 1;
+      break;
+
+    case MODE_SERVER:
+      switch (inst->mode) {
+        case MODE_CLIENT:
+          /* Standard case where he's a server and we're the client */
+          proc_packet = 1;
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_BROADCAST:
+      /* Just ignore these */
+      break;
+
+    default:
+      /* Obviously ignore */
+      break;
+  }
+
+  if (proc_packet) {
+    /* Check if the reply was received by the socket that sent the request */
+    if (local_addr->sock_fd != inst->local_addr.sock_fd) {
+      DEBUG_LOG("Packet received by wrong socket %d (expected %d)",
+                local_addr->sock_fd, inst->local_addr.sock_fd);
+      return 0;
+    }
+
+    /* Ignore packets from offline sources */
+    if (inst->opmode == MD_OFFLINE || inst->tx_suspended) {
+      DEBUG_LOG("Packet from offline source");
+      return 0;
+    }
+
+    return process_response(inst, local_addr, rx_ts, message, &info);
+  } else if (proc_as_unknown) {
+    NCR_ProcessRxUnknown(&inst->remote_addr, local_addr, rx_ts, message, length);
+    /* It's not a reply to our request, don't return success */
+    return 0;
+  } else {
+    DEBUG_LOG("NTP packet discarded mode=%d our_mode=%u", (int)info.mode, inst->mode);
+    return 0;
+  }
+}
+
+/* ================================================== */
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we don't know (not our server or peer) */
+
+void
+NCR_ProcessRxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                     NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  NTP_PacketInfo info;
+  NTP_Mode my_mode;
+  NTP_Local_Timestamp local_tx, *tx_ts;
+  NTP_int64 ntp_rx, *local_ntp_rx;
+  int log_index, interleaved, poll, version;
+  uint32_t kod;
+
+  /* Ignore the packet if it wasn't received by server socket */
+  if (!NIO_IsServerSocket(local_addr->sock_fd)) {
+    DEBUG_LOG("NTP request packet received by client socket %d", local_addr->sock_fd);
+    return;
+  }
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  if (!ADF_IsAllowed(access_auth_table, &remote_addr->ip_addr)) {
+    DEBUG_LOG("NTP packet received from unauthorised host %s",
+              UTI_IPToString(&remote_addr->ip_addr));
+    return;
+  }
+
+  switch (info.mode) {
+    case MODE_ACTIVE:
+      /* We are symmetric passive, even though we don't ever lock to him */
+      my_mode = MODE_PASSIVE;
+      break;
+    case MODE_CLIENT:
+      /* Reply with server packet */
+      my_mode = MODE_SERVER;
+      break;
+    case MODE_UNDEFINED:
+      /* Check if it is an NTPv1 client request (NTPv1 packets have a reserved
+         field instead of the mode field and the actual mode is determined from
+         the port numbers).  Don't ever respond with a mode 0 packet! */
+      if (info.version == 1 && remote_addr->port != NTP_PORT) {
+        my_mode = MODE_SERVER;
+        break;
+      }
+      /* Fall through */
+    default:
+      /* Discard */
+      DEBUG_LOG("NTP packet discarded mode=%d", (int)info.mode);
+      return;
+  }
+
+  kod = 0;
+  log_index = CLG_LogServiceAccess(CLG_NTP, &remote_addr->ip_addr, &rx_ts->ts);
+
+  /* Don't reply to all requests if the rate is excessive */
+  if (log_index >= 0 && CLG_LimitServiceRate(CLG_NTP, log_index)) {
+      DEBUG_LOG("NTP packet discarded to limit response rate");
+      return;
+  }
+
+  /* Check authentication */
+  if (!NAU_CheckRequestAuth(message, &info, &kod)) {
+    DEBUG_LOG("NTP packet failed auth mode=%d kod=%"PRIx32, (int)info.auth.mode, kod);
+
+    /* Don't respond unless a non-zero KoD was returned */
+    if (kod == 0)
+      return;
+  } else if (info.auth.mode != NTP_AUTH_NONE && info.auth.mode != NTP_AUTH_MSSNTP) {
+    CLG_LogAuthNtpRequest();
+  }
+
+  local_ntp_rx = NULL;
+  tx_ts = NULL;
+  interleaved = 0;
+
+  /* Handle requests formed in the interleaved mode.  As an optimisation to
+     avoid saving all receive timestamps, require that the origin timestamp
+     has the lowest bit equal to 1, which indicates it was set to one of our
+     receive timestamps instead of transmit timestamps or zero.  Respond in the
+     interleaved mode if the receive timestamp is found and it has a non-zero
+     transmit timestamp (this is verified in transmit_packet()).  For a new
+     client starting with a zero origin timestamp, the third response is the
+     earliest one that can be interleaved. */
+  if (kod == 0 && log_index >= 0 && info.version == 4 &&
+      message->originate_ts.lo & htonl(1) &&
+      UTI_CompareNtp64(&message->receive_ts, &message->transmit_ts) != 0) {
+    ntp_rx = message->originate_ts;
+    local_ntp_rx = &ntp_rx;
+    UTI_ZeroTimespec(&local_tx.ts);
+    interleaved = CLG_GetNtpTxTimestamp(&ntp_rx, &local_tx.ts);
+
+    tx_ts = &local_tx;
+    if (interleaved)
+      CLG_DisableNtpTimestamps(&ntp_rx);
+  }
+
+  /* Suggest the client to increase its polling interval if it indicates
+     the interval is shorter than the rate limiting interval */
+  poll = CLG_GetNtpMinPoll();
+  poll = MAX(poll, message->poll);
+
+  /* Respond with the same version */
+  version = info.version;
+
+  /* Send a reply */
+  if (!transmit_packet(my_mode, interleaved, poll, version, kod, info.ext_field_flags, NULL,
+                       &message->receive_ts, &message->transmit_ts,
+                       rx_ts, tx_ts, local_ntp_rx, NULL, remote_addr, local_addr,
+                       message, &info))
+    return;
+
+  if (local_ntp_rx)
+    CLG_SaveNtpTimestamps(local_ntp_rx, tx_ts ? &tx_ts->ts : NULL);
+}
+
+/* ================================================== */
+
+static void
+update_tx_timestamp(NTP_Local_Timestamp *tx_ts, NTP_Local_Timestamp *new_tx_ts,
+                    NTP_int64 *local_ntp_rx, NTP_int64 *local_ntp_tx, NTP_Packet *message)
+{
+  double delay;
+
+  if (UTI_IsZeroTimespec(&tx_ts->ts)) {
+    DEBUG_LOG("Unexpected TX update");
+    return;
+  }
+
+  /* Check if this is the last packet that was sent */
+  if ((local_ntp_rx && UTI_CompareNtp64(&message->receive_ts, local_ntp_rx)) ||
+      (local_ntp_tx && UTI_CompareNtp64(&message->transmit_ts, local_ntp_tx))) {
+    DEBUG_LOG("RX/TX timestamp mismatch");
+    return;
+  }
+
+  delay = UTI_DiffTimespecsToDouble(&new_tx_ts->ts, &tx_ts->ts);
+
+  if (delay < 0.0 || delay > MAX_TX_DELAY) {
+    DEBUG_LOG("Unacceptable TX delay %.9f", delay);
+    return;
+  }
+
+  *tx_ts = *new_tx_ts;
+
+  DEBUG_LOG("Updated TX timestamp delay=%.9f", delay);
+}
+
+/* ================================================== */
+
+void
+NCR_ProcessTxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                   NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  NTP_PacketInfo info;
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  /* Server and passive mode packets are responses to unknown sources */
+  if (info.mode != MODE_CLIENT && info.mode != MODE_ACTIVE) {
+    NCR_ProcessTxUnknown(&inst->remote_addr, local_addr, tx_ts, message, length);
+    return;
+  }
+
+  update_tx_timestamp(&inst->local_tx, tx_ts, &inst->local_ntp_rx, &inst->local_ntp_tx,
+                      message);
+}
+
+/* ================================================== */
+
+void
+NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                     NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  NTP_Local_Timestamp old_tx, new_tx;
+  NTP_int64 *local_ntp_rx;
+  NTP_PacketInfo info;
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  if (info.mode == MODE_BROADCAST)
+    return;
+
+  if (SMT_IsEnabled() && info.mode == MODE_SERVER)
+    UTI_AddDoubleToTimespec(&tx_ts->ts, SMT_GetOffset(&tx_ts->ts), &tx_ts->ts);
+
+  local_ntp_rx = &message->receive_ts;
+  new_tx = *tx_ts;
+
+  if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &old_tx.ts))
+    return;
+
+  /* Undo a clock adjustment between the RX and TX timestamps to minimise error
+     in the delay measured by the client */
+  CLG_UndoNtpTxTimestampSlew(local_ntp_rx, &new_tx.ts);
+
+  update_tx_timestamp(&old_tx, &new_tx, local_ntp_rx, NULL, message);
+
+  CLG_UpdateNtpTxTimestamp(local_ntp_rx, &new_tx.ts);
+}
+
+/* ================================================== */
+
+void
+NCR_SlewTimes(NCR_Instance inst, struct timespec *when, double dfreq, double doffset)
+{
+  double delta;
+
+  if (!UTI_IsZeroTimespec(&inst->local_rx.ts))
+    UTI_AdjustTimespec(&inst->local_rx.ts, when, &inst->local_rx.ts, &delta, dfreq, doffset);
+  if (!UTI_IsZeroTimespec(&inst->local_tx.ts))
+    UTI_AdjustTimespec(&inst->local_tx.ts, when, &inst->local_tx.ts, &delta, dfreq, doffset);
+  if (!UTI_IsZeroTimespec(&inst->prev_local_tx.ts))
+    UTI_AdjustTimespec(&inst->prev_local_tx.ts, when, &inst->prev_local_tx.ts, &delta, dfreq,
+                       doffset);
+  if (!UTI_IsZeroTimespec(&inst->init_local_rx.ts))
+    UTI_AdjustTimespec(&inst->init_local_rx.ts, when, &inst->init_local_rx.ts, &delta, dfreq,
+                       doffset);
+
+  if (inst->filter)
+    SPF_SlewSamples(inst->filter, when, dfreq, doffset);
+}
+
+/* ================================================== */
+
+static void
+set_connectivity(NCR_Instance inst, SRC_Connectivity connectivity)
+{
+  if (connectivity == SRC_MAYBE_ONLINE)
+    connectivity = NIO_IsServerConnectable(&inst->remote_addr) ? SRC_ONLINE : SRC_OFFLINE;
+
+  switch (connectivity) {
+    case SRC_ONLINE:
+      switch (inst->opmode) {
+        case MD_ONLINE:
+          /* Nothing to do */
+          break;
+        case MD_OFFLINE:
+          inst->opmode = MD_ONLINE;
+          NCR_ResetInstance(inst);
+          start_initial_timeout(inst);
+          if (inst->auto_iburst)
+            NCR_InitiateSampleBurst(inst, IBURST_GOOD_SAMPLES, IBURST_TOTAL_SAMPLES);
+          break;
+        case MD_BURST_WAS_ONLINE:
+          /* Will revert */
+          break;
+        case MD_BURST_WAS_OFFLINE:
+          inst->opmode = MD_BURST_WAS_ONLINE;
+          break;
+        default:
+          assert(0);
+      }
+      break;
+    case SRC_OFFLINE:
+      switch (inst->opmode) {
+        case MD_ONLINE:
+          take_offline(inst);
+          break;
+        case MD_OFFLINE:
+          break;
+        case MD_BURST_WAS_ONLINE:
+          inst->opmode = MD_BURST_WAS_OFFLINE;
+          break;
+        case MD_BURST_WAS_OFFLINE:
+          break;
+        default:
+          assert(0);
+      }
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_SetConnectivity(NCR_Instance inst, SRC_Connectivity connectivity)
+{
+  OperatingMode prev_opmode;
+  int was_online, is_online;
+
+  prev_opmode = inst->opmode;
+
+  set_connectivity(inst, connectivity);
+
+  /* Report an important change */
+  was_online = prev_opmode == MD_ONLINE || prev_opmode == MD_BURST_WAS_ONLINE;
+  is_online = inst->opmode == MD_ONLINE || inst->opmode == MD_BURST_WAS_ONLINE;
+  if (was_online != is_online)
+    LOG(LOGS_INFO, "Source %s %s",
+        UTI_IPToString(&inst->remote_addr.ip_addr), is_online ? "online" : "offline");
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMinpoll(NCR_Instance inst, int new_minpoll)
+{
+  if (new_minpoll < MIN_POLL || new_minpoll > MAX_POLL)
+    return;
+  inst->minpoll = new_minpoll;
+  LOG(LOGS_INFO, "Source %s new minpoll %d", UTI_IPToString(&inst->remote_addr.ip_addr), new_minpoll);
+  if (inst->maxpoll < inst->minpoll)
+    NCR_ModifyMaxpoll(inst, inst->minpoll);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxpoll(NCR_Instance inst, int new_maxpoll)
+{
+  if (new_maxpoll < MIN_POLL || new_maxpoll > MAX_POLL)
+    return;
+  inst->maxpoll = new_maxpoll;
+  LOG(LOGS_INFO, "Source %s new maxpoll %d", UTI_IPToString(&inst->remote_addr.ip_addr), new_maxpoll);
+  if (inst->minpoll > inst->maxpoll)
+    NCR_ModifyMinpoll(inst, inst->maxpoll);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelay(NCR_Instance inst, double new_max_delay)
+{
+  inst->max_delay = CLAMP(0.0, new_max_delay, MAX_MAXDELAY);
+  LOG(LOGS_INFO, "Source %s new maxdelay %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelayratio(NCR_Instance inst, double new_max_delay_ratio)
+{
+  inst->max_delay_ratio = CLAMP(0.0, new_max_delay_ratio, MAX_MAXDELAYRATIO);
+  LOG(LOGS_INFO, "Source %s new maxdelayratio %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay_ratio);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelaydevratio(NCR_Instance inst, double new_max_delay_dev_ratio)
+{
+  inst->max_delay_dev_ratio = CLAMP(0.0, new_max_delay_dev_ratio, MAX_MAXDELAYDEVRATIO);
+  LOG(LOGS_INFO, "Source %s new maxdelaydevratio %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay_dev_ratio);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMinstratum(NCR_Instance inst, int new_min_stratum)
+{
+  inst->min_stratum = new_min_stratum;
+  LOG(LOGS_INFO, "Source %s new minstratum %d",
+      UTI_IPToString(&inst->remote_addr.ip_addr), new_min_stratum);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyPolltarget(NCR_Instance inst, int new_poll_target)
+{
+  inst->poll_target = new_poll_target;
+  LOG(LOGS_INFO, "Source %s new polltarget %d",
+      UTI_IPToString(&inst->remote_addr.ip_addr), new_poll_target);
+}
+
+/* ================================================== */
+
+void
+NCR_InitiateSampleBurst(NCR_Instance inst, int n_good_samples, int n_total_samples)
+{
+
+  if (inst->mode == MODE_CLIENT) {
+
+    /* We want to prevent burst mode being used on symmetric active
+       associations - it will play havoc with the peer's sampling
+       strategy. (This obviously relies on us having the peer
+       configured that way if he has us configured symmetric active -
+       but there's not much else we can do.) */
+
+    switch (inst->opmode) {
+      case MD_BURST_WAS_OFFLINE:
+      case MD_BURST_WAS_ONLINE:
+        /* If already burst sampling, don't start again */
+        break;
+
+      case MD_ONLINE:
+      case MD_OFFLINE:
+        inst->opmode = inst->opmode == MD_ONLINE ?
+          MD_BURST_WAS_ONLINE : MD_BURST_WAS_OFFLINE;
+        inst->burst_good_samples_to_go = n_good_samples;
+        inst->burst_total_samples_to_go = n_total_samples;
+        start_initial_timeout(inst);
+        break;
+      default:
+        assert(0);
+        break;
+    }
+  }
+
+}
+
+/* ================================================== */
+
+void
+NCR_ReportSource(NCR_Instance inst, RPT_SourceReport *report, struct timespec *now)
+{
+  report->poll = get_transmit_poll(inst);
+
+  switch (inst->mode) {
+    case MODE_CLIENT:
+      report->mode = RPT_NTP_CLIENT;
+      break;
+    case MODE_ACTIVE:
+      report->mode = RPT_NTP_PEER;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_GetAuthReport(NCR_Instance inst, RPT_AuthReport *report)
+{
+  NAU_GetReport(inst->auth, report);
+}
+
+/* ================================================== */
+
+void
+NCR_GetNTPReport(NCR_Instance inst, RPT_NTPReport *report)
+{
+  *report = inst->report;
+}
+
+/* ================================================== */
+
+int
+NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+ {
+  ADF_Status status;
+
+  if (allow) {
+    if (all) {
+      status = ADF_AllowAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Allow(access_auth_table, ip_addr, subnet_bits);
+    }
+  } else {
+    if (all) {
+      status = ADF_DenyAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Deny(access_auth_table, ip_addr, subnet_bits);
+    }
+  }
+
+  if (status != ADF_SUCCESS)
+    return 0;
+
+  /* Keep server sockets open only when an address allowed */
+  if (allow) {
+    NTP_Remote_Address remote_addr;
+
+    if (server_sock_fd4 == INVALID_SOCK_FD &&
+        ADF_IsAnyAllowed(access_auth_table, IPADDR_INET4)) {
+      remote_addr.ip_addr.family = IPADDR_INET4;
+      remote_addr.port = 0;
+      server_sock_fd4 = NIO_OpenServerSocket(&remote_addr);
+    }
+    if (server_sock_fd6 == INVALID_SOCK_FD &&
+        ADF_IsAnyAllowed(access_auth_table, IPADDR_INET6)) {
+      remote_addr.ip_addr.family = IPADDR_INET6;
+      remote_addr.port = 0;
+      server_sock_fd6 = NIO_OpenServerSocket(&remote_addr);
+    }
+  } else {
+    if (server_sock_fd4 != INVALID_SOCK_FD &&
+        !ADF_IsAnyAllowed(access_auth_table, IPADDR_INET4)) {
+      NIO_CloseServerSocket(server_sock_fd4);
+      server_sock_fd4 = INVALID_SOCK_FD;
+    }
+    if (server_sock_fd6 != INVALID_SOCK_FD &&
+        !ADF_IsAnyAllowed(access_auth_table, IPADDR_INET6)) {
+      NIO_CloseServerSocket(server_sock_fd6);
+      server_sock_fd6 = INVALID_SOCK_FD;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NCR_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return ADF_IsAllowed(access_auth_table, ip_addr);
+}
+
+/* ================================================== */
+
+void
+NCR_IncrementActivityCounters(NCR_Instance inst, int *online, int *offline,
+                              int *burst_online, int *burst_offline)
+{
+  switch (inst->opmode) {
+    case MD_BURST_WAS_OFFLINE:
+      ++*burst_offline;
+      break;
+    case MD_BURST_WAS_ONLINE:
+      ++*burst_online;
+      break;
+    case MD_ONLINE:
+      ++*online;
+      break;
+    case MD_OFFLINE:
+      ++*offline;
+      break;
+    default:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+NTP_Remote_Address *
+NCR_GetRemoteAddress(NCR_Instance inst) 
+{
+  return &inst->remote_addr;
+}
+
+/* ================================================== */
+
+uint32_t
+NCR_GetLocalRefid(NCR_Instance inst)
+{
+  return UTI_IPToRefid(&inst->local_addr.ip_addr);
+}
+
+/* ================================================== */
+
+int NCR_IsSyncPeer(NCR_Instance inst)
+{
+  return SRC_IsSyncPeer(inst->source);
+}
+
+/* ================================================== */
+
+void
+NCR_DumpAuthData(NCR_Instance inst)
+{
+  NAU_DumpData(inst->auth);
+}
+
+/* ================================================== */
+
+static void
+broadcast_timeout(void *arg)
+{
+  BroadcastDestination *destination;
+  NTP_int64 orig_ts;
+  NTP_Local_Timestamp recv_ts;
+  int poll;
+
+  destination = ARR_GetElement(broadcasts, (long)arg);
+  poll = round(log(destination->interval) / log(2.0));
+
+  UTI_ZeroNtp64(&orig_ts);
+  zero_local_timestamp(&recv_ts);
+
+  transmit_packet(MODE_BROADCAST, 0, poll, NTP_VERSION, 0, 0, destination->auth,
+                  &orig_ts, &orig_ts, &recv_ts, NULL, NULL, NULL,
+                  &destination->addr, &destination->local_addr, NULL, NULL);
+
+  /* Requeue timeout.  We don't care if interval drifts gradually. */
+  SCH_AddTimeoutInClass(destination->interval, get_separation(poll), SAMPLING_RANDOMNESS,
+                        SCH_NtpBroadcastClass, broadcast_timeout, arg);
+}
+
+/* ================================================== */
+
+void
+NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval)
+{
+  BroadcastDestination *destination;
+
+  destination = (BroadcastDestination *)ARR_GetNewElement(broadcasts);
+
+  destination->addr = *addr;
+  destination->local_addr.ip_addr.family = IPADDR_UNSPEC;
+  destination->local_addr.if_index = INVALID_IF_INDEX;
+  destination->local_addr.sock_fd = NIO_OpenServerSocket(&destination->addr);
+  destination->auth = NAU_CreateNoneInstance();
+  destination->interval = CLAMP(1, interval, 1 << MAX_POLL);
+
+  SCH_AddTimeoutInClass(destination->interval, MAX_SAMPLING_SEPARATION, SAMPLING_RANDOMNESS,
+                        SCH_NtpBroadcastClass, broadcast_timeout,
+                        (void *)(long)(ARR_GetSize(broadcasts) - 1));
+}
diff --git a/ntp_core.h b/ntp_core.h
new file mode 100644
index 0000000..33f2bb8
--- /dev/null
+++ b/ntp_core.h
@@ -0,0 +1,144 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the main NTP protocol engine
+  */
+
+#ifndef GOT_NTP_CORE_H
+#define GOT_NTP_CORE_H
+
+#include "sysincl.h"
+
+#include "addressing.h"
+#include "srcparams.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef enum {
+  NTP_SERVER, NTP_PEER
+} NTP_Source_Type;
+
+typedef enum {
+  NTP_TS_DAEMON = 0,
+  NTP_TS_KERNEL,
+  NTP_TS_HARDWARE
+} NTP_Timestamp_Source;
+
+typedef struct {
+  struct timespec ts;
+  double err;
+  NTP_Timestamp_Source source;
+} NTP_Local_Timestamp;
+
+/* This is a private data type used for storing the instance record for
+   each source that we are chiming with */
+typedef struct NCR_Instance_Record *NCR_Instance;
+
+/* Init and fini functions */
+extern void NCR_Initialise(void);
+extern void NCR_Finalise(void);
+
+/* Get a new instance for a server or peer */
+extern NCR_Instance NCR_CreateInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                                       SourceParameters *params, const char *name);
+
+/* Destroy an instance */
+extern void NCR_DestroyInstance(NCR_Instance instance);
+
+/* Start an instance */
+extern void NCR_StartInstance(NCR_Instance instance);
+
+/* Reset an instance */
+extern void NCR_ResetInstance(NCR_Instance inst);
+
+/* Reset polling interval of an instance */
+extern void NCR_ResetPoll(NCR_Instance instance);
+
+/* Change the remote address of an instance */
+extern void NCR_ChangeRemoteAddress(NCR_Instance inst, NTP_Remote_Address *remote_addr,
+                                    int ntp_only);
+
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we have an ongoing protocol exchange with */
+extern int NCR_ProcessRxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                              NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a new packet arrives off the network,
+   and we do not recognize its source */
+extern void NCR_ProcessRxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                                 NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a packet is sent to a source we have
+   an ongoing protocol exchange with */
+extern void NCR_ProcessTxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                               NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a packet is sent to a destination we
+   do not recognize */
+extern void NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                                 NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* Slew receive and transmit times in instance records */
+extern void NCR_SlewTimes(NCR_Instance inst, struct timespec *when, double dfreq, double doffset);
+
+/* Take a particular source online (i.e. start sampling it) or offline
+   (i.e. stop sampling it) */
+extern void NCR_SetConnectivity(NCR_Instance inst, SRC_Connectivity connectivity);
+
+extern void NCR_ModifyMinpoll(NCR_Instance inst, int new_minpoll);
+
+extern void NCR_ModifyMaxpoll(NCR_Instance inst, int new_maxpoll);
+
+extern void NCR_ModifyMaxdelay(NCR_Instance inst, double new_max_delay);
+
+extern void NCR_ModifyMaxdelayratio(NCR_Instance inst, double new_max_delay_ratio);
+
+extern void NCR_ModifyMaxdelaydevratio(NCR_Instance inst, double new_max_delay_dev_ratio);
+
+extern void NCR_ModifyMinstratum(NCR_Instance inst, int new_min_stratum);
+
+extern void NCR_ModifyPolltarget(NCR_Instance inst, int new_poll_target);
+
+extern void NCR_InitiateSampleBurst(NCR_Instance inst, int n_good_samples, int n_total_samples);
+
+extern void NCR_ReportSource(NCR_Instance inst, RPT_SourceReport *report, struct timespec *now);
+extern void NCR_GetAuthReport(NCR_Instance inst, RPT_AuthReport *report);
+extern void NCR_GetNTPReport(NCR_Instance inst, RPT_NTPReport *report);
+
+extern int NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all);
+extern int NCR_CheckAccessRestriction(IPAddr *ip_addr);
+
+extern void NCR_IncrementActivityCounters(NCR_Instance inst, int *online, int *offline, 
+                                          int *burst_online, int *burst_offline);
+
+extern NTP_Remote_Address *NCR_GetRemoteAddress(NCR_Instance instance);
+
+extern uint32_t NCR_GetLocalRefid(NCR_Instance inst);
+
+extern int NCR_IsSyncPeer(NCR_Instance instance);
+
+extern void NCR_DumpAuthData(NCR_Instance inst);
+
+extern void NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval);
+
+#endif /* GOT_NTP_CORE_H */
diff --git a/ntp_ext.c b/ntp_ext.c
new file mode 100644
index 0000000..d2babb1
--- /dev/null
+++ b/ntp_ext.c
@@ -0,0 +1,192 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions for adding and parsing NTPv4 extension fields
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "ntp_ext.h"
+
+struct ExtFieldHeader {
+  uint16_t type;
+  uint16_t length;
+};
+
+/* ================================================== */
+
+static int
+format_field(unsigned char *buffer, int buffer_length, int start,
+             int type, int body_length, int *length, void **body)
+{
+  struct ExtFieldHeader *header;
+
+  if (buffer_length < 0 || start < 0 || buffer_length <= start ||
+      buffer_length - start < sizeof (*header) || start % 4 != 0)
+    return 0;
+
+  header = (struct ExtFieldHeader *)(buffer + start);
+
+  if (body_length < 0 || sizeof (*header) + body_length > 0xffff ||
+      start + sizeof (*header) + body_length > buffer_length || body_length % 4 != 0)
+    return 0;
+
+  header->type = htons(type);
+  header->length = htons(sizeof (*header) + body_length);
+  *length = sizeof (*header) + body_length;
+  *body = header + 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_SetField(unsigned char *buffer, int buffer_length, int start,
+             int type, void *body, int body_length, int *length)
+{
+  void *ef_body;
+
+  if (!format_field(buffer, buffer_length, start, type, body_length, length, &ef_body))
+    return 0;
+
+  memcpy(ef_body, body, body_length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_AddBlankField(NTP_Packet *packet, NTP_PacketInfo *info, int type, int body_length, void **body)
+{
+  int ef_length, length = info->length;
+
+  if (length < NTP_HEADER_LENGTH || length >= sizeof (*packet) || length % 4 != 0)
+    return 0;
+
+  /* Only NTPv4 packets can have extension fields */
+  if (info->version != 4)
+    return 0;
+
+  if (!format_field((unsigned char *)packet, sizeof (*packet), length,
+                    type, body_length, &ef_length, body))
+    return 0;
+
+  if (ef_length < NTP_MIN_EF_LENGTH)
+    return 0;
+
+  info->length += ef_length;
+  info->ext_fields++;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_AddField(NTP_Packet *packet, NTP_PacketInfo *info,
+             int type, void *body, int body_length)
+{
+  void *ef_body;
+
+  if (!NEF_AddBlankField(packet, info, type, body_length, &ef_body))
+    return 0;
+
+  memcpy(ef_body, body, body_length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_ParseSingleField(unsigned char *buffer, int buffer_length, int start,
+                     int *length, int *type, void **body, int *body_length)
+{
+  struct ExtFieldHeader *header;
+  int ef_length;
+
+  if (buffer_length < 0 || start < 0 || buffer_length <= start ||
+      buffer_length - start < sizeof (*header))
+    return 0;
+
+  header = (struct ExtFieldHeader *)(buffer + start);
+
+  assert(sizeof (*header) == 4);
+
+  ef_length = ntohs(header->length);
+
+  if (ef_length < (int)(sizeof (*header)) || start + ef_length > buffer_length ||
+      ef_length % 4 != 0)
+    return 0;
+
+  if (length)
+    *length = ef_length;
+  if (type)
+    *type = ntohs(header->type);
+  if (body)
+    *body = header + 1;
+  if (body_length)
+    *body_length = ef_length - sizeof (*header);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_ParseField(NTP_Packet *packet, int packet_length, int start,
+               int *length, int *type, void **body, int *body_length)
+{
+  int ef_length;
+
+  if (packet_length <= NTP_HEADER_LENGTH || packet_length > sizeof (*packet) ||
+      packet_length <= start || packet_length % 4 != 0 ||
+      start < NTP_HEADER_LENGTH || start % 4 != 0)
+    return 0;
+
+  /* Only NTPv4 packets have extension fields */
+  if (NTP_LVM_TO_VERSION(packet->lvm) != 4)
+    return 0;
+
+  /* Check if the remaining data is a MAC.  RFC 7822 specifies the maximum
+     length of a MAC in NTPv4 packets in order to enable deterministic
+     parsing. */
+  if (packet_length - start <= NTP_MAX_V4_MAC_LENGTH)
+    return 0;
+
+  if (!NEF_ParseSingleField((unsigned char *)packet, packet_length, start,
+                            &ef_length, type, body, body_length))
+    return 0;
+
+  if (ef_length < NTP_MIN_EF_LENGTH)
+    return 0;
+
+  if (length)
+    *length = ef_length;
+
+  return 1;
+}
diff --git a/ntp_ext.h b/ntp_ext.h
new file mode 100644
index 0000000..7405be8
--- /dev/null
+++ b/ntp_ext.h
@@ -0,0 +1,43 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NTP extension fields
+  */
+
+#ifndef GOT_NTP_EXT_H
+#define GOT_NTP_EXT_H
+
+#include "ntp.h"
+
+extern int NEF_SetField(unsigned char *buffer, int buffer_length, int start,
+                        int type, void *body, int body_length, int *length);
+extern int NEF_AddBlankField(NTP_Packet *packet, NTP_PacketInfo *info, int type,
+                             int body_length, void **body);
+extern int NEF_AddField(NTP_Packet *packet, NTP_PacketInfo *info,
+                        int type, void *body, int body_length);
+extern int NEF_ParseSingleField(unsigned char *buffer, int buffer_length, int start,
+                                int *length, int *type, void **body, int *body_length);
+extern int NEF_ParseField(NTP_Packet *packet, int packet_length, int start,
+                          int *length, int *type, void **body, int *body_length);
+
+#endif
diff --git a/ntp_io.c b/ntp_io.c
new file mode 100644
index 0000000..86e3f26
--- /dev/null
+++ b/ntp_io.c
@@ -0,0 +1,610 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Timo Teras  2009
+ * Copyright (C) Miroslav Lichvar  2009, 2013-2016, 2018-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file deals with the IO aspects of reading and writing NTP packets
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "memory.h"
+#include "ntp_io.h"
+#include "ntp_core.h"
+#include "ntp_sources.h"
+#include "ptp.h"
+#include "sched.h"
+#include "socket.h"
+#include "local.h"
+#include "logging.h"
+#include "conf.h"
+#include "privops.h"
+#include "util.h"
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include "ntp_io_linux.h"
+#endif
+
+#define INVALID_SOCK_FD -1
+
+/* The server/peer and client sockets for IPv4 and IPv6 */
+static int server_sock_fd4;
+static int server_sock_fd6;
+static int client_sock_fd4;
+static int client_sock_fd6;
+
+/* Reference counters for server sockets to keep them open only when needed */
+static int server_sock_ref4;
+static int server_sock_ref6;
+
+/* Flag indicating we create a new connected client socket for each
+   server instead of sharing client_sock_fd4 and client_sock_fd6 */
+static int separate_client_sockets;
+
+/* Flag indicating the server sockets are not created dynamically when needed,
+   either to have a socket for client requests when separate client sockets
+   are disabled and client port is equal to server port, or the server port is
+   disabled */
+static int permanent_server_sockets;
+
+/* Flag indicating the server IPv4 socket is bound to an address */
+static int bound_server_sock_fd4;
+
+/* PTP event port, or 0 if disabled */
+static int ptp_port;
+
+/* Shared server/client sockets for NTP-over-PTP */
+static int ptp_sock_fd4;
+static int ptp_sock_fd6;
+
+/* Buffer for transmitted NTP-over-PTP messages */
+static PTP_NtpMessage *ptp_message;
+
+/* Flag indicating that we have been initialised */
+static int initialised=0;
+
+/* ================================================== */
+
+/* Forward prototypes */
+static void read_from_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static int
+open_socket(int family, int local_port, int client_only, IPSockAddr *remote_addr)
+{
+  int sock_fd, sock_flags, dscp, events = SCH_FILE_INPUT;
+  IPSockAddr local_addr;
+  char *iface;
+
+  if (!SCK_IsIpFamilyEnabled(family))
+    return INVALID_SOCK_FD;
+
+  if (!client_only) {
+    CNF_GetBindAddress(family, &local_addr.ip_addr);
+    iface = CNF_GetBindNtpInterface();
+  } else {
+    CNF_GetBindAcquisitionAddress(family, &local_addr.ip_addr);
+    iface = CNF_GetBindAcquisitionInterface();
+  }
+
+  local_addr.port = local_port;
+
+  sock_flags = SCK_FLAG_RX_DEST_ADDR | SCK_FLAG_PRIV_BIND;
+  if (!client_only)
+    sock_flags |= SCK_FLAG_BROADCAST;
+
+  sock_fd = SCK_OpenUdpSocket(remote_addr, &local_addr, iface, sock_flags);
+  if (sock_fd < 0) {
+    if (!client_only)
+      LOG(LOGS_ERR, "Could not open NTP socket on %s", UTI_IPSockAddrToString(&local_addr));
+    return INVALID_SOCK_FD;
+  }
+
+  dscp = CNF_GetNtpDscp();
+  if (dscp > 0 && dscp < 64) {
+#ifdef IP_TOS
+    if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_TOS, dscp << 2))
+      ;
+#endif
+  }
+
+  if (!client_only && family == IPADDR_INET4 && local_addr.port > 0)
+    bound_server_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;
+
+  /* Enable kernel/HW timestamping of packets */
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (!NIO_Linux_SetTimestampSocketOptions(sock_fd, client_only, &events))
+#endif
+    if (!SCK_EnableKernelRxTimestamping(sock_fd))
+      ;
+
+  /* Register handler for read and possibly exception events on the socket */
+  SCH_AddFileHandler(sock_fd, events, read_from_socket, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+open_separate_client_socket(IPSockAddr *remote_addr)
+{
+  return open_socket(remote_addr->ip_addr.family, 0, 1, remote_addr);
+}
+
+/* ================================================== */
+
+static void
+close_socket(int sock_fd)
+{
+  if (sock_fd == INVALID_SOCK_FD)
+    return;
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  NIO_Linux_NotifySocketClosing(sock_fd);
+#endif
+  SCH_RemoveFileHandler(sock_fd);
+  SCK_CloseSocket(sock_fd);
+}
+
+/* ================================================== */
+
+void
+NIO_Initialise(void)
+{
+  int server_port, client_port;
+
+  assert(!initialised);
+  initialised = 1;
+
+#ifdef PRIVOPS_BINDSOCKET
+  SCK_SetPrivBind(PRV_BindSocket);
+#endif
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  NIO_Linux_Initialise();
+#else
+  if (1) {
+    CNF_HwTsInterface *conf_iface;
+    if (CNF_GetHwTsInterface(0, &conf_iface))
+      LOG_FATAL("HW timestamping not supported");
+  }
+#endif
+
+  server_port = CNF_GetNTPPort();
+  client_port = CNF_GetAcquisitionPort();
+
+  /* Use separate connected sockets if client port is negative */
+  separate_client_sockets = client_port < 0;
+  if (client_port < 0)
+    client_port = 0;
+
+  permanent_server_sockets = !server_port || (!separate_client_sockets &&
+                                              client_port == server_port);
+
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+  client_sock_fd4 = INVALID_SOCK_FD;
+  client_sock_fd6 = INVALID_SOCK_FD;
+  server_sock_ref4 = 0;
+  server_sock_ref6 = 0;
+
+  if (permanent_server_sockets && server_port) {
+    server_sock_fd4 = open_socket(IPADDR_INET4, server_port, 0, NULL);
+    server_sock_fd6 = open_socket(IPADDR_INET6, server_port, 0, NULL);
+  }
+
+  if (!separate_client_sockets) {
+    if (client_port != server_port || !server_port) {
+      client_sock_fd4 = open_socket(IPADDR_INET4, client_port, 1, NULL);
+      client_sock_fd6 = open_socket(IPADDR_INET6, client_port, 1, NULL);
+    } else {
+      client_sock_fd4 = server_sock_fd4;
+      client_sock_fd6 = server_sock_fd6;
+    }
+  }
+
+  if ((server_port && permanent_server_sockets &&
+       server_sock_fd4 == INVALID_SOCK_FD && server_sock_fd6 == INVALID_SOCK_FD) ||
+      (!separate_client_sockets &&
+       client_sock_fd4 == INVALID_SOCK_FD && client_sock_fd6 == INVALID_SOCK_FD)) {
+    LOG_FATAL("Could not open NTP sockets");
+  }
+
+  ptp_port = CNF_GetPtpPort();
+  ptp_sock_fd4 = INVALID_SOCK_FD;
+  ptp_sock_fd6 = INVALID_SOCK_FD;
+  ptp_message = NULL;
+
+  if (ptp_port > 0) {
+    ptp_sock_fd4 = open_socket(IPADDR_INET4, ptp_port, 0, NULL);
+    ptp_sock_fd6 = open_socket(IPADDR_INET6, ptp_port, 0, NULL);
+    ptp_message = MallocNew(PTP_NtpMessage);
+  }
+}
+
+/* ================================================== */
+
+void
+NIO_Finalise(void)
+{
+  if (server_sock_fd4 != client_sock_fd4)
+    close_socket(client_sock_fd4);
+  close_socket(server_sock_fd4);
+  server_sock_fd4 = client_sock_fd4 = INVALID_SOCK_FD;
+
+  if (server_sock_fd6 != client_sock_fd6)
+    close_socket(client_sock_fd6);
+  close_socket(server_sock_fd6);
+  server_sock_fd6 = client_sock_fd6 = INVALID_SOCK_FD;
+
+  close_socket(ptp_sock_fd4);
+  close_socket(ptp_sock_fd6);
+  ptp_sock_fd4 = ptp_sock_fd6 = INVALID_SOCK_FD;
+  Free(ptp_message);
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  NIO_Linux_Finalise();
+#endif
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+int
+NIO_OpenClientSocket(NTP_Remote_Address *remote_addr)
+{
+  switch (remote_addr->ip_addr.family) {
+    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd4;
+    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd6;
+    default:
+      return INVALID_SOCK_FD;
+  }
+}
+
+/* ================================================== */
+
+int
+NIO_OpenServerSocket(NTP_Remote_Address *remote_addr)
+{
+  switch (remote_addr->ip_addr.family) {
+    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
+      if (permanent_server_sockets)
+        return server_sock_fd4;
+      if (server_sock_fd4 == INVALID_SOCK_FD)
+        server_sock_fd4 = open_socket(IPADDR_INET4, CNF_GetNTPPort(), 0, NULL);
+      if (server_sock_fd4 != INVALID_SOCK_FD)
+        server_sock_ref4++;
+      return server_sock_fd4;
+    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
+      if (permanent_server_sockets)
+        return server_sock_fd6;
+      if (server_sock_fd6 == INVALID_SOCK_FD)
+        server_sock_fd6 = open_socket(IPADDR_INET6, CNF_GetNTPPort(), 0, NULL);
+      if (server_sock_fd6 != INVALID_SOCK_FD)
+        server_sock_ref6++;
+      return server_sock_fd6;
+    default:
+      return INVALID_SOCK_FD;
+  }
+}
+
+/* ================================================== */
+
+static int
+is_ptp_socket(int sock_fd)
+{
+  return ptp_port > 0 && sock_fd != INVALID_SOCK_FD &&
+    (sock_fd == ptp_sock_fd4 || sock_fd == ptp_sock_fd6);
+}
+
+/* ================================================== */
+
+void
+NIO_CloseClientSocket(int sock_fd)
+{
+  if (is_ptp_socket(sock_fd))
+    return;
+
+  if (separate_client_sockets)
+    close_socket(sock_fd);
+}
+
+/* ================================================== */
+
+void
+NIO_CloseServerSocket(int sock_fd)
+{
+  if (permanent_server_sockets || sock_fd == INVALID_SOCK_FD || is_ptp_socket(sock_fd))
+    return;
+
+  if (sock_fd == server_sock_fd4) {
+    if (--server_sock_ref4 <= 0) {
+      close_socket(server_sock_fd4);
+      server_sock_fd4 = INVALID_SOCK_FD;
+    }
+  } else if (sock_fd == server_sock_fd6) {
+    if (--server_sock_ref6 <= 0) {
+      close_socket(server_sock_fd6);
+      server_sock_fd6 = INVALID_SOCK_FD;
+    }
+  } else {
+    assert(0);
+  }
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerSocket(int sock_fd)
+{
+  return sock_fd != INVALID_SOCK_FD &&
+    (sock_fd == server_sock_fd4 || sock_fd == server_sock_fd6 || is_ptp_socket(sock_fd));
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerSocketOpen(void)
+{
+  return server_sock_fd4 != INVALID_SOCK_FD || server_sock_fd6 != INVALID_SOCK_FD ||
+    ptp_sock_fd4 != INVALID_SOCK_FD || ptp_sock_fd6 != INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerConnectable(NTP_Remote_Address *remote_addr)
+{
+  int sock_fd;
+
+  sock_fd = open_separate_client_socket(remote_addr);
+  if (sock_fd == INVALID_SOCK_FD)
+    return 0;
+
+  close_socket(sock_fd);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_message(SCK_Message *message, int sock_fd, int event)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  struct timespec sched_ts;
+
+  SCH_GetLastEventTime(&local_ts.ts, &local_ts.err, NULL);
+  local_ts.source = NTP_TS_DAEMON;
+  sched_ts = local_ts.ts;
+
+  if (message->addr_type != SCK_ADDR_IP) {
+    DEBUG_LOG("Unexpected address type");
+    return;
+  }
+
+  local_addr.ip_addr = message->local_addr.ip;
+  local_addr.if_index = message->if_index;;
+  local_addr.sock_fd = sock_fd;
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (NIO_Linux_ProcessMessage(message, &local_addr, &local_ts, event))
+    return;
+#else
+  if (!UTI_IsZeroTimespec(&message->timestamp.kernel)) {
+    LCL_CookTime(&message->timestamp.kernel, &local_ts.ts, &local_ts.err);
+    local_ts.source = NTP_TS_KERNEL;
+  }
+#endif
+
+  if (local_ts.source != NTP_TS_DAEMON)
+    DEBUG_LOG("Updated RX timestamp delay=%.9f tss=%u",
+              UTI_DiffTimespecsToDouble(&sched_ts, &local_ts.ts), local_ts.source);
+
+  if (!NIO_UnwrapMessage(message, sock_fd))
+    return;
+
+  /* Just ignore the packet if it's not of a recognized length */
+  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet)) {
+    DEBUG_LOG("Unexpected length");
+    return;
+  }
+
+  NSR_ProcessRx(&message->remote_addr.ip, &local_addr, &local_ts, message->data, message->length);
+}
+
+/* ================================================== */
+
+static void
+read_from_socket(int sock_fd, int event, void *anything)
+{
+  SCK_Message *messages;
+  int i, received, flags = 0;
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (NIO_Linux_ProcessEvent(sock_fd, event))
+    return;
+#endif
+
+  if (event == SCH_FILE_EXCEPTION) {
+#ifdef HAVE_LINUX_TIMESTAMPING
+    flags |= SCK_FLAG_MSG_ERRQUEUE;
+#else
+    assert(0);
+#endif
+  }
+
+  messages = SCK_ReceiveMessages(sock_fd, flags, &received);
+  if (!messages)
+    return;
+
+  for (i = 0; i < received; i++)
+    process_message(&messages[i], sock_fd, event);
+}
+
+/* ================================================== */
+
+int
+NIO_UnwrapMessage(SCK_Message *message, int sock_fd)
+{
+  PTP_NtpMessage *msg;
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (message->length <= PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  msg = message->data;
+
+  if (msg->header.type != PTP_TYPE_DELAY_REQ || msg->header.version != PTP_VERSION ||
+      ntohs(msg->header.length) != message->length ||
+      msg->header.domain != PTP_DOMAIN_NTP ||
+      ntohs(msg->header.flags) != PTP_FLAG_UNICAST ||
+      ntohs(msg->tlv_header.type) != PTP_TLV_NTP ||
+      ntohs(msg->tlv_header.length) != message->length - PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected PTP message");
+    return 0;
+  }
+
+  message->data = (char *)message->data + PTP_NTP_PREFIX_LENGTH;
+  message->length -= PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Unwrapped PTP->NTP len=%d", message->length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+wrap_message(SCK_Message *message, int sock_fd)
+{
+  assert(PTP_NTP_PREFIX_LENGTH == 48);
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (!ptp_message)
+    return 0;
+
+  if (message->length < NTP_HEADER_LENGTH ||
+      message->length + PTP_NTP_PREFIX_LENGTH > sizeof (*ptp_message)) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  memset(ptp_message, 0, PTP_NTP_PREFIX_LENGTH);
+  ptp_message->header.type = PTP_TYPE_DELAY_REQ;
+  ptp_message->header.version = PTP_VERSION;
+  ptp_message->header.length = htons(PTP_NTP_PREFIX_LENGTH + message->length);
+  ptp_message->header.domain = PTP_DOMAIN_NTP;
+  ptp_message->header.flags = htons(PTP_FLAG_UNICAST);
+  ptp_message->tlv_header.type = htons(PTP_TLV_NTP);
+  ptp_message->tlv_header.length = htons(message->length);
+  memcpy((char *)ptp_message + PTP_NTP_PREFIX_LENGTH, message->data, message->length);
+
+  message->data = ptp_message;
+  message->length += PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Wrapped NTP->PTP len=%d", message->length - PTP_NTP_PREFIX_LENGTH);
+
+  return 1;
+}
+
+/* ================================================== */
+/* Send a packet to remote address from local address */
+
+int
+NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
+               NTP_Local_Address *local_addr, int length, int process_tx)
+{
+  SCK_Message message;
+
+  assert(initialised);
+
+  if (local_addr->sock_fd == INVALID_SOCK_FD) {
+    DEBUG_LOG("No socket to send to %s", UTI_IPSockAddrToString(remote_addr));
+    return 0;
+  }
+
+  SCK_InitMessage(&message, SCK_ADDR_IP);
+
+  message.data = packet;
+  message.length = length;
+
+  if (!wrap_message(&message, local_addr->sock_fd))
+    return 0;
+
+  /* Specify remote address if the socket is not connected */
+  if (NIO_IsServerSocket(local_addr->sock_fd) || !separate_client_sockets) {
+    message.remote_addr.ip.ip_addr = remote_addr->ip_addr;
+    message.remote_addr.ip.port = remote_addr->port;
+  }
+
+  message.local_addr.ip = local_addr->ip_addr;
+
+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  message.if_index = SCK_IsLinkLocalIPAddress(&message.remote_addr.ip.ip_addr) ?
+                       local_addr->if_index : INVALID_IF_INDEX;
+
+#if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
+  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
+  if (message.local_addr.ip.family == IPADDR_INET4 &&
+      (bound_server_sock_fd4 || !NIO_IsServerSocket(local_addr->sock_fd)))
+    message.local_addr.ip.family = IPADDR_UNSPEC;
+#endif
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (process_tx)
+    NIO_Linux_RequestTxTimestamp(&message, local_addr->sock_fd);
+#endif
+
+  if (!SCK_SendMessage(local_addr->sock_fd, &message, 0))
+    return 0;
+
+  return 1;
+}
diff --git a/ntp_io.h b/ntp_io.h
new file mode 100644
index 0000000..19ffeed
--- /dev/null
+++ b/ntp_io.h
@@ -0,0 +1,70 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the NTP socket I/O bits.
+
+  */
+
+#ifndef GOT_NTP_IO_H
+#define GOT_NTP_IO_H
+
+#include "ntp.h"
+#include "addressing.h"
+#include "socket.h"
+
+/* Function to initialise the module. */
+extern void NIO_Initialise(void);
+
+/* Function to finalise the module */
+extern void NIO_Finalise(void);
+
+/* Function to obtain a socket for sending client packets */
+extern int NIO_OpenClientSocket(NTP_Remote_Address *remote_addr);
+
+/* Function to obtain a socket for sending server/peer packets */
+extern int NIO_OpenServerSocket(NTP_Remote_Address *remote_addr);
+
+/* Function to close a socket returned by NIO_OpenClientSocket() */
+extern void NIO_CloseClientSocket(int sock_fd);
+
+/* Function to close a socket returned by NIO_OpenServerSocket() */
+extern void NIO_CloseServerSocket(int sock_fd);
+
+/* Function to check if socket is a server socket */
+extern int NIO_IsServerSocket(int sock_fd);
+
+/* Function to check if a server socket is currently open */
+extern int NIO_IsServerSocketOpen(void);
+
+/* Function to check if client packets can be sent to a server */
+extern int NIO_IsServerConnectable(NTP_Remote_Address *remote_addr);
+
+/* Function to unwrap an NTP message from non-native transport (e.g. PTP) */
+extern int NIO_UnwrapMessage(SCK_Message *message, int sock_fd);
+
+/* Function to transmit a packet */
+extern int NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
+                          NTP_Local_Address *local_addr, int length, int process_tx);
+
+#endif /* GOT_NTP_IO_H */
diff --git a/ntp_io_linux.c b/ntp_io_linux.c
new file mode 100644
index 0000000..004a4d4
--- /dev/null
+++ b/ntp_io_linux.c
@@ -0,0 +1,847 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2019, 2021-2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions for NTP I/O specific to Linux
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <ifaddrs.h>
+#include <linux/ethtool.h>
+#include <linux/net_tstamp.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+
+#include "array.h"
+#include "conf.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "ntp_io_linux.h"
+#include "ntp_sources.h"
+#include "sched.h"
+#include "socket.h"
+#include "sys_linux.h"
+#include "util.h"
+
+struct Interface {
+  char name[IF_NAMESIZE];
+  int if_index;
+  int phc_fd;
+  int phc_mode;
+  int phc_nocrossts;
+  /* Link speed in mbit/s */
+  int link_speed;
+  /* Start of UDP data at layer 2 for IPv4 and IPv6 */
+  int l2_udp4_ntp_start;
+  int l2_udp6_ntp_start;
+  /* Compensation of errors in TX and RX timestamping */
+  double tx_comp;
+  double rx_comp;
+  HCL_Instance clock;
+};
+
+/* Number of PHC readings per HW clock sample */
+#define PHC_READINGS 25
+
+/* Minimum interval between PHC readings */
+#define MIN_PHC_POLL -6
+
+/* Maximum acceptable offset between SW/HW and daemon timestamp */
+#define MAX_TS_DELAY 1.0
+
+/* Array of Interfaces */
+static ARR_Instance interfaces;
+
+/* RX/TX and TX-specific timestamping socket options */
+static int ts_flags;
+static int ts_tx_flags;
+
+/* Flag indicating the socket options can't be changed in control messages */
+static int permanent_ts_options;
+
+/* When sending client requests to a close and fast server, it is possible that
+   a response will be received before the HW transmit timestamp of the request
+   itself.  To avoid processing of the response without the HW timestamp, we
+   monitor events returned by select() and suspend reading of packets from the
+   receive queue for up to 200 microseconds.  As the requests are normally
+   separated by at least 200 milliseconds, it is sufficient to monitor and
+   suspend one socket at a time. */
+static int monitored_socket;
+static int suspended_socket;
+static SCH_TimeoutID resume_timeout_id;
+
+#define RESUME_TIMEOUT 200.0e-6
+
+/* Unbound socket keeping the kernel RX timestamping permanently enabled
+   in order to avoid a race condition between receiving a server response
+   and the kernel actually starting to timestamp received packets after
+   enabling the timestamping and sending a request */
+static int dummy_rxts_socket;
+
+#define INVALID_SOCK_FD -3
+
+/* ================================================== */
+
+static int
+add_interface(CNF_HwTsInterface *conf_iface)
+{
+  struct ethtool_ts_info ts_info;
+  struct hwtstamp_config ts_config;
+  struct ifreq req;
+  int sock_fd, if_index, phc_fd, req_hwts_flags, rx_filter;
+  unsigned int i;
+  struct Interface *iface;
+
+  /* Check if the interface was not already added */
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    if (!strcmp(conf_iface->name, ((struct Interface *)ARR_GetElement(interfaces, i))->name))
+      return 1;
+  }
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  memset(&req, 0, sizeof (req));
+  memset(&ts_info, 0, sizeof (ts_info));
+
+  if (snprintf(req.ifr_name, sizeof (req.ifr_name), "%s", conf_iface->name) >=
+      sizeof (req.ifr_name)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if (ioctl(sock_fd, SIOCGIFINDEX, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCGIFINDEX", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if_index = req.ifr_ifindex;
+
+  ts_info.cmd = ETHTOOL_GET_TS_INFO;
+  req.ifr_data = (char *)&ts_info;
+
+  if (ioctl(sock_fd, SIOCETHTOOL, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCETHTOOL", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  req_hwts_flags = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_TX_HARDWARE |
+                   SOF_TIMESTAMPING_RAW_HARDWARE;
+  if ((ts_info.so_timestamping & req_hwts_flags) != req_hwts_flags) {
+    DEBUG_LOG("HW timestamping not supported on %s", req.ifr_name);
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if (ts_info.phc_index < 0) {
+    DEBUG_LOG("PHC missing on %s", req.ifr_name);
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  switch (conf_iface->rxfilter) {
+    case CNF_HWTS_RXFILTER_ANY:
+#ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_NTP_ALL))
+        rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+      else
+#endif
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))
+        rx_filter = HWTSTAMP_FILTER_ALL;
+      else
+        rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+    case CNF_HWTS_RXFILTER_NONE:
+      rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+#ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
+    case CNF_HWTS_RXFILTER_NTP:
+      rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+      break;
+#endif
+    case CNF_HWTS_RXFILTER_PTP:
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_L4_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_L4_EVENT;
+      else if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_EVENT;
+      else
+        rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+    default:
+      rx_filter = HWTSTAMP_FILTER_ALL;
+      break;
+  }
+
+  ts_config.flags = 0;
+  ts_config.tx_type = HWTSTAMP_TX_ON;
+  ts_config.rx_filter = rx_filter;
+  req.ifr_data = (char *)&ts_config;
+
+  if (ioctl(sock_fd, SIOCSHWTSTAMP, &req)) {
+    LOG(errno == EPERM ? LOGS_ERR : LOGS_DEBUG,
+        "ioctl(%s) failed : %s", "SIOCSHWTSTAMP", strerror(errno));
+
+    /* Check the current timestamping configuration in case this interface
+       allows only reading of the configuration and it was already configured
+       as requested */
+    req.ifr_data = (char *)&ts_config;
+#ifdef SIOCGHWTSTAMP
+    if (ioctl(sock_fd, SIOCGHWTSTAMP, &req) ||
+        ts_config.tx_type != HWTSTAMP_TX_ON || ts_config.rx_filter != rx_filter)
+#endif
+    {
+      SCK_CloseSocket(sock_fd);
+      return 0;
+    }
+  }
+
+  SCK_CloseSocket(sock_fd);
+
+  phc_fd = SYS_Linux_OpenPHC(NULL, ts_info.phc_index);
+  if (phc_fd < 0)
+    return 0;
+
+  iface = ARR_GetNewElement(interfaces);
+
+  snprintf(iface->name, sizeof (iface->name), "%s", conf_iface->name);
+  iface->if_index = if_index;
+  iface->phc_fd = phc_fd;
+  iface->phc_mode = 0;
+  iface->phc_nocrossts = conf_iface->nocrossts;
+
+  /* Start with 1 gbit and no VLANs or IPv4/IPv6 options */
+  iface->link_speed = 1000;
+  iface->l2_udp4_ntp_start = 42;
+  iface->l2_udp6_ntp_start = 62;
+
+  iface->tx_comp = conf_iface->tx_comp;
+  iface->rx_comp = conf_iface->rx_comp;
+
+  iface->clock = HCL_CreateInstance(conf_iface->min_samples, conf_iface->max_samples,
+                                    UTI_Log2ToDouble(MAX(conf_iface->minpoll, MIN_PHC_POLL)),
+                                    conf_iface->precision);
+
+  LOG(LOGS_INFO, "Enabled HW timestamping %son %s",
+      ts_config.rx_filter == HWTSTAMP_FILTER_NONE ? "(TX only) " : "", iface->name);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+add_all_interfaces(CNF_HwTsInterface *conf_iface_all)
+{
+  CNF_HwTsInterface conf_iface;
+  struct ifaddrs *ifaddr, *ifa;
+  int r;
+
+  conf_iface = *conf_iface_all;
+
+  if (getifaddrs(&ifaddr)) {
+    DEBUG_LOG("getifaddrs() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  for (r = 0, ifa = ifaddr; ifa; ifa = ifa->ifa_next) {
+    conf_iface.name = ifa->ifa_name;
+    if (add_interface(&conf_iface))
+      r = 1;
+  }
+  
+  freeifaddrs(ifaddr);
+
+  /* Return success if at least one interface was added */
+  return r;
+}
+
+/* ================================================== */
+
+static void
+update_interface_speed(struct Interface *iface)
+{
+  struct ethtool_cmd cmd;
+  struct ifreq req;
+  int sock_fd, link_speed;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return;
+
+  memset(&req, 0, sizeof (req));
+  memset(&cmd, 0, sizeof (cmd));
+
+  snprintf(req.ifr_name, sizeof (req.ifr_name), "%s", iface->name);
+  cmd.cmd = ETHTOOL_GSET;
+  req.ifr_data = (char *)&cmd;
+
+  if (ioctl(sock_fd, SIOCETHTOOL, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCETHTOOL", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  SCK_CloseSocket(sock_fd);
+
+  link_speed = ethtool_cmd_speed(&cmd);
+
+  if (iface->link_speed != link_speed) {
+    iface->link_speed = link_speed;
+    DEBUG_LOG("Updated speed of %s to %d Mb/s", iface->name, link_speed);
+  }
+}
+
+/* ================================================== */
+
+#if defined(HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO) || defined(HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW)
+static int
+check_timestamping_option(int option)
+{
+  int sock_fd;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPING, option)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  SCK_CloseSocket(sock_fd);
+  return 1;
+}
+#endif
+
+/* ================================================== */
+
+static int
+open_dummy_socket(void)
+{
+  int sock_fd, events = 0;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!NIO_Linux_SetTimestampSocketOptions(sock_fd, 1, &events)) {
+    SCK_CloseSocket(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_Initialise(void)
+{
+  CNF_HwTsInterface *conf_iface;
+  unsigned int i;
+  int hwts;
+
+  interfaces = ARR_CreateInstance(sizeof (struct Interface));
+
+  /* Enable HW timestamping on specified interfaces.  If "*" was specified, try
+     all interfaces.  If no interface was specified, enable SW timestamping. */
+
+  for (i = hwts = 0; CNF_GetHwTsInterface(i, &conf_iface); i++) {
+    if (!strcmp("*", conf_iface->name))
+      continue;
+    if (!add_interface(conf_iface))
+      LOG_FATAL("Could not enable HW timestamping on %s", conf_iface->name);
+    hwts = 1;
+  }
+
+  for (i = 0; CNF_GetHwTsInterface(i, &conf_iface); i++) {
+    if (strcmp("*", conf_iface->name))
+      continue;
+    if (add_all_interfaces(conf_iface))
+      hwts = 1;
+    break;
+  }
+
+  ts_flags = SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_RX_SOFTWARE;
+  ts_tx_flags = SOF_TIMESTAMPING_TX_SOFTWARE;
+
+  if (hwts) {
+    ts_flags |= SOF_TIMESTAMPING_RAW_HARDWARE | SOF_TIMESTAMPING_RX_HARDWARE;
+    ts_tx_flags |= SOF_TIMESTAMPING_TX_HARDWARE;
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO
+    if (check_timestamping_option(SOF_TIMESTAMPING_OPT_PKTINFO))
+      ts_flags |= SOF_TIMESTAMPING_OPT_PKTINFO;
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW
+    if (check_timestamping_option(SOF_TIMESTAMPING_OPT_TX_SWHW))
+      ts_flags |= SOF_TIMESTAMPING_OPT_TX_SWHW;
+#endif
+  }
+
+  /* Enable IP_PKTINFO in messages looped back to the error queue */
+  ts_flags |= SOF_TIMESTAMPING_OPT_CMSG;
+
+  /* Kernels before 4.7 ignore timestamping flags set in control messages */
+  permanent_ts_options = !SYS_Linux_CheckKernelVersion(4, 7);
+
+  monitored_socket = INVALID_SOCK_FD;
+  suspended_socket = INVALID_SOCK_FD;
+  dummy_rxts_socket = INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_Finalise(void)
+{
+  struct Interface *iface;
+  unsigned int i;
+
+  if (dummy_rxts_socket != INVALID_SOCK_FD)
+    SCK_CloseSocket(dummy_rxts_socket);
+
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    iface = ARR_GetElement(interfaces, i);
+    HCL_DestroyInstance(iface->clock);
+    close(iface->phc_fd);
+  }
+
+  ARR_DestroyInstance(interfaces);
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events)
+{
+  int val, flags;
+
+  if (!ts_flags)
+    return 0;
+
+  /* Enable SCM_TIMESTAMPING control messages and the socket's error queue in
+     order to receive our transmitted packets with more accurate timestamps */
+
+  val = 1;
+  flags = ts_flags;
+
+  if (client_only || permanent_ts_options)
+    flags |= ts_tx_flags;
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_SELECT_ERR_QUEUE, val)) {
+    ts_flags = 0;
+    return 0;
+  }
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPING, flags)) {
+    ts_flags = 0;
+    return 0;
+  }
+
+  *events |= SCH_FILE_EXCEPTION;
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+resume_socket(int sock_fd)
+{
+  if (monitored_socket == sock_fd)
+    monitored_socket = INVALID_SOCK_FD;
+
+  if (sock_fd == INVALID_SOCK_FD || sock_fd != suspended_socket)
+    return;
+
+  suspended_socket = INVALID_SOCK_FD;
+
+  SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_INPUT, 1);
+
+  DEBUG_LOG("Resumed RX processing %s timeout fd=%d",
+            resume_timeout_id ? "before" : "on", sock_fd);
+
+  if (resume_timeout_id) {
+    SCH_RemoveTimeout(resume_timeout_id);
+    resume_timeout_id = 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+resume_timeout(void *arg)
+{
+  resume_timeout_id = 0;
+  resume_socket(suspended_socket);
+}
+
+/* ================================================== */
+
+static void
+suspend_socket(int sock_fd)
+{
+  resume_socket(suspended_socket);
+
+  suspended_socket = sock_fd;
+
+  SCH_SetFileHandlerEvent(suspended_socket, SCH_FILE_INPUT, 0);
+  resume_timeout_id = SCH_AddTimeoutByDelay(RESUME_TIMEOUT, resume_timeout, NULL);
+
+  DEBUG_LOG("Suspended RX processing fd=%d", sock_fd);
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_ProcessEvent(int sock_fd, int event)
+{
+  if (sock_fd != monitored_socket)
+    return 0;
+
+  if (event == SCH_FILE_INPUT) {
+    suspend_socket(monitored_socket);
+    monitored_socket = INVALID_SOCK_FD;
+
+    /* Don't process the message yet */
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+static struct Interface *
+get_interface(int if_index)
+{
+  struct Interface *iface;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    iface = ARR_GetElement(interfaces, i);
+    if (iface->if_index != if_index)
+      continue;
+
+    return iface;
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+process_hw_timestamp(struct Interface *iface, struct timespec *hw_ts,
+                     NTP_Local_Timestamp *local_ts, int rx_ntp_length, int family,
+                     int l2_length)
+{
+  struct timespec sample_phc_ts, sample_sys_ts, sample_local_ts, ts;
+  struct timespec phc_readings[PHC_READINGS][3];
+  double rx_correction, ts_delay, phc_err, local_err;
+  int n_readings;
+
+  if (HCL_NeedsNewSample(iface->clock, &local_ts->ts)) {
+    n_readings = SYS_Linux_GetPHCReadings(iface->phc_fd, iface->phc_nocrossts,
+                                          &iface->phc_mode, PHC_READINGS, phc_readings);
+    if (n_readings > 0 &&
+        HCL_ProcessReadings(iface->clock, n_readings, phc_readings,
+                             &sample_phc_ts, &sample_sys_ts, &phc_err)) {
+      LCL_CookTime(&sample_sys_ts, &sample_local_ts, &local_err);
+      HCL_AccumulateSample(iface->clock, &sample_phc_ts, &sample_local_ts,
+                           phc_err + local_err);
+
+      update_interface_speed(iface);
+    }
+  }
+
+  /* We need to transpose RX timestamps as hardware timestamps are normally
+     preamble timestamps and RX timestamps in NTP are supposed to be trailer
+     timestamps.  If we don't know the length of the packet at layer 2, we
+     make an assumption that UDP data start at the same position as in the
+     last transmitted packet which had a HW TX timestamp. */
+  if (rx_ntp_length && iface->link_speed) {
+    if (!l2_length)
+      l2_length = (family == IPADDR_INET4 ? iface->l2_udp4_ntp_start :
+                   iface->l2_udp6_ntp_start) + rx_ntp_length;
+
+    /* Include the frame check sequence (FCS) */
+    l2_length += 4;
+
+    rx_correction = l2_length / (1.0e6 / 8 * iface->link_speed);
+
+    UTI_AddDoubleToTimespec(hw_ts, rx_correction, hw_ts);
+  }
+
+  if (!HCL_CookTime(iface->clock, hw_ts, &ts, &local_err))
+    return;
+
+  if (!rx_ntp_length && iface->tx_comp)
+    UTI_AddDoubleToTimespec(&ts, iface->tx_comp, &ts);
+  else if (rx_ntp_length && iface->rx_comp)
+    UTI_AddDoubleToTimespec(&ts, -iface->rx_comp, &ts);
+
+  ts_delay = UTI_DiffTimespecsToDouble(&local_ts->ts, &ts);
+
+  if (fabs(ts_delay) > MAX_TS_DELAY) {
+    DEBUG_LOG("Unacceptable timestamp delay %.9f", ts_delay);
+    return;
+  }
+
+  local_ts->ts = ts;
+  local_ts->err = local_err;
+  local_ts->source = NTP_TS_HARDWARE;
+}
+
+/* ================================================== */
+
+static void
+process_sw_timestamp(struct timespec *sw_ts, NTP_Local_Timestamp *local_ts)
+{
+  double ts_delay, local_err;
+  struct timespec ts;
+
+  LCL_CookTime(sw_ts, &ts, &local_err);
+
+  ts_delay = UTI_DiffTimespecsToDouble(&local_ts->ts, &ts);
+
+  if (fabs(ts_delay) > MAX_TS_DELAY) {
+    DEBUG_LOG("Unacceptable timestamp delay %.9f", ts_delay);
+    return;
+  }
+
+  local_ts->ts = ts;
+  local_ts->err = local_err;
+  local_ts->source = NTP_TS_KERNEL;
+}
+
+/* ================================================== */
+/* Extract UDP data from a layer 2 message.  Supported is Ethernet
+   with optional VLAN tags. */
+
+static int
+extract_udp_data(unsigned char *msg, NTP_Remote_Address *remote_addr, int len)
+{
+  unsigned char *msg_start = msg;
+
+  remote_addr->ip_addr.family = IPADDR_UNSPEC;
+  remote_addr->port = 0;
+
+  /* Skip MACs */
+  if (len < 12)
+    return 0;
+  len -= 12, msg += 12;
+
+  /* Skip VLAN tag(s) if present */
+  while (len >= 4 && msg[0] == 0x81 && msg[1] == 0x00)
+    len -= 4, msg += 4;
+
+  /* Skip IPv4 or IPv6 ethertype */
+  if (len < 2 || !((msg[0] == 0x08 && msg[1] == 0x00) ||
+                   (msg[0] == 0x86 && msg[1] == 0xdd)))
+    return 0;
+  len -= 2, msg += 2;
+
+  /* Parse destination address and port from IPv4/IPv6 and UDP headers */
+  if (len >= 20 && msg[0] >> 4 == 4) {
+    int ihl = (msg[0] & 0xf) * 4;
+    uint32_t addr;
+
+    if (len < ihl + 8 || msg[9] != 17)
+      return 0;
+
+    memcpy(&addr, msg + 16, sizeof (addr));
+    remote_addr->ip_addr.addr.in4 = ntohl(addr);
+    remote_addr->port = ntohs(*(uint16_t *)(msg + ihl + 2));
+    remote_addr->ip_addr.family = IPADDR_INET4;
+    len -= ihl + 8, msg += ihl + 8;
+#ifdef FEAT_IPV6
+  } else if (len >= 48 && msg[0] >> 4 == 6) {
+    int eh_len, next_header = msg[6];
+
+    memcpy(&remote_addr->ip_addr.addr.in6, msg + 24, sizeof (remote_addr->ip_addr.addr.in6));
+    len -= 40, msg += 40;
+
+    /* Skip IPv6 extension headers if present */
+    while (next_header != 17) {
+      switch (next_header) {
+        case 44:  /* Fragment Header */
+          /* Process only the first fragment */
+          if (ntohs(*(uint16_t *)(msg + 2)) >> 3 != 0)
+            return 0;
+          eh_len = 8;
+          break;
+        case 0:   /* Hop-by-Hop Options */
+        case 43:  /* Routing Header */
+        case 60:  /* Destination Options */
+        case 135: /* Mobility Header */
+          eh_len = 8 * (msg[1] + 1);
+          break;
+        case 51:  /* Authentication Header */
+          eh_len = 4 * (msg[1] + 2);
+          break;
+        default:
+          return 0;
+      }
+
+      if (eh_len < 8 || len < eh_len + 8)
+        return 0;
+
+      next_header = msg[0];
+      len -= eh_len, msg += eh_len;
+    }
+
+    remote_addr->port = ntohs(*(uint16_t *)(msg + 2));
+    remote_addr->ip_addr.family = IPADDR_INET6;
+    len -= 8, msg += 8;
+#endif
+  } else {
+    return 0;
+  }
+
+  /* Move the message to fix alignment of its fields */
+  if (len > 0)
+    memmove(msg_start, msg, len);
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
+                         NTP_Local_Timestamp *local_ts, int event)
+{
+  struct Interface *iface;
+  int is_tx, ts_if_index, l2_length;
+
+  is_tx = event == SCH_FILE_EXCEPTION;
+  iface = NULL;
+
+  ts_if_index = message->timestamp.if_index;
+  if (ts_if_index == INVALID_IF_INDEX)
+    ts_if_index = message->if_index;
+  l2_length = message->timestamp.l2_length;
+
+  if (!UTI_IsZeroTimespec(&message->timestamp.hw)) {
+    iface = get_interface(ts_if_index);
+    if (iface) {
+      process_hw_timestamp(iface, &message->timestamp.hw, local_ts, !is_tx ? message->length : 0,
+                           message->remote_addr.ip.ip_addr.family, l2_length);
+    } else {
+      DEBUG_LOG("HW clock not found for interface %d", ts_if_index);
+    }
+
+    /* If a HW transmit timestamp was received, resume processing
+       of non-error messages on this socket */
+    if (is_tx)
+      resume_socket(local_addr->sock_fd);
+  }
+
+  if (local_ts->source == NTP_TS_DAEMON && !UTI_IsZeroTimespec(&message->timestamp.kernel) &&
+      (!is_tx || UTI_IsZeroTimespec(&message->timestamp.hw))) {
+    process_sw_timestamp(&message->timestamp.kernel, local_ts);
+  }
+
+  /* If the kernel is slow with enabling RX timestamping, open a dummy
+     socket to keep the kernel RX timestamping permanently enabled */
+  if (!is_tx && local_ts->source == NTP_TS_DAEMON && ts_flags) {
+    DEBUG_LOG("Missing kernel RX timestamp");
+    if (dummy_rxts_socket == INVALID_SOCK_FD)
+      dummy_rxts_socket = open_dummy_socket();
+  }
+
+  /* Return the message if it's not received from the error queue */
+  if (!is_tx)
+    return 0;
+
+  /* The data from the error queue includes all layers up to UDP.  We have to
+     extract the UDP data and also the destination address with port as there
+     currently doesn't seem to be a better way to get them both. */
+  l2_length = message->length;
+  message->length = extract_udp_data(message->data, &message->remote_addr.ip, message->length);
+
+  DEBUG_LOG("Extracted message for %s fd=%d len=%d",
+            UTI_IPSockAddrToString(&message->remote_addr.ip),
+            local_addr->sock_fd, message->length);
+
+  /* Update assumed position of UDP data at layer 2 for next received packet */
+  if (iface && message->length) {
+    if (message->remote_addr.ip.ip_addr.family == IPADDR_INET4)
+      iface->l2_udp4_ntp_start = l2_length - message->length;
+    else if (message->remote_addr.ip.ip_addr.family == IPADDR_INET6)
+      iface->l2_udp6_ntp_start = l2_length - message->length;
+  }
+
+  /* Drop the message if it has no timestamp or its processing failed */
+  if (local_ts->source == NTP_TS_DAEMON) {
+    DEBUG_LOG("Missing TX timestamp");
+    return 1;
+  }
+
+  if (!NIO_UnwrapMessage(message, local_addr->sock_fd))
+    return 1;
+
+  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet))
+    return 1;
+
+  NSR_ProcessTx(&message->remote_addr.ip, local_addr, local_ts, message->data, message->length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd)
+{
+  if (!ts_flags)
+    return;
+
+  /* If a HW transmit timestamp is requested on a client socket, monitor
+     events on the socket in order to avoid processing of a fast response
+     without the HW timestamp of the request */
+  if (ts_tx_flags & SOF_TIMESTAMPING_TX_HARDWARE && !NIO_IsServerSocket(sock_fd))
+    monitored_socket = sock_fd;
+
+  /* Check if TX timestamping is disabled on this socket */
+  if (permanent_ts_options || !NIO_IsServerSocket(sock_fd))
+    return;
+
+  message->timestamp.tx_flags = ts_tx_flags;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_NotifySocketClosing(int sock_fd)
+{
+  resume_socket(sock_fd);
+}
diff --git a/ntp_io_linux.h b/ntp_io_linux.h
new file mode 100644
index 0000000..4d3af13
--- /dev/null
+++ b/ntp_io_linux.h
@@ -0,0 +1,47 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the Linux-specific NTP socket I/O bits.
+  */
+
+#ifndef GOT_NTP_IO_LINUX_H
+#define GOT_NTP_IO_LINUX_H
+
+#include "socket.h"
+
+extern void NIO_Linux_Initialise(void);
+
+extern void NIO_Linux_Finalise(void);
+
+extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);
+
+extern int NIO_Linux_ProcessEvent(int sock_fd, int event);
+
+extern int NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
+                                    NTP_Local_Timestamp *local_ts, int event);
+
+extern void NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd);
+
+extern void NIO_Linux_NotifySocketClosing(int sock_fd);
+
+#endif
diff --git a/ntp_signd.c b/ntp_signd.c
new file mode 100644
index 0000000..77b3249
--- /dev/null
+++ b/ntp_signd.c
@@ -0,0 +1,341 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Support for MS-SNTP authentication in Samba (ntp_signd)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "conf.h"
+#include "logging.h"
+#include "ntp_io.h"
+#include "ntp_signd.h"
+#include "sched.h"
+#include "socket.h"
+#include "util.h"
+
+/* Declarations per samba/source4/librpc/idl/ntp_signd.idl */
+
+#define SIGND_VERSION 0
+
+typedef enum {
+  SIGN_TO_CLIENT = 0,
+  ASK_SERVER_TO_SIGN = 1,
+  CHECK_SERVER_SIGNATURE = 2,
+  SIGNING_SUCCESS = 3,
+  SIGNING_FAILURE = 4,
+} SigndOp;
+
+typedef struct {
+  uint32_t length;
+  uint32_t version;
+  uint32_t op;
+  uint16_t packet_id;
+  uint16_t _pad;
+  uint32_t key_id;
+  NTP_Packet packet_to_sign;
+} SigndRequest;
+
+typedef struct {
+  uint32_t length;
+  uint32_t version;
+  uint32_t op;
+  uint32_t packet_id;
+  NTP_Packet signed_packet;
+} SigndResponse;
+
+typedef struct {
+  NTP_Remote_Address remote_addr;
+  NTP_Local_Address local_addr;
+
+  int sent;
+  int received;
+  int request_length;
+  struct timespec request_ts;
+  SigndRequest request;
+  SigndResponse response;
+} SignInstance;
+
+/* As the communication with ntp_signd is asynchronous, incoming packets are
+   saved in a queue in order to avoid loss when they come in bursts */
+
+#define MAX_QUEUE_LENGTH 16U
+#define NEXT_QUEUE_INDEX(index) (((index) + 1) % MAX_QUEUE_LENGTH)
+#define IS_QUEUE_EMPTY() (queue_head == queue_tail)
+
+/* Fixed-size array of SignInstance */
+static ARR_Instance queue;
+static unsigned int queue_head;
+static unsigned int queue_tail;
+
+#define INVALID_SOCK_FD (-6)
+
+/* Unix domain socket connected to ntp_signd */
+static int sock_fd;
+
+/* Flag indicating if the MS-SNTP authentication is enabled */
+static int enabled;
+
+/* ================================================== */
+
+static void read_write_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static void
+close_socket(void)
+{
+  SCH_RemoveFileHandler(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  sock_fd = INVALID_SOCK_FD;
+
+  /* Empty the queue */
+  queue_head = queue_tail = 0;
+}
+
+/* ================================================== */
+
+static int
+open_socket(void)
+{
+  char path[PATH_MAX];
+
+  if (sock_fd != INVALID_SOCK_FD)
+    return 1;
+
+  if (snprintf(path, sizeof (path), "%s/socket", CNF_GetNtpSigndSocket()) >= sizeof (path)) {
+    DEBUG_LOG("signd socket path too long");
+    return 0;
+  }
+
+  sock_fd = SCK_OpenUnixStreamSocket(path, NULL, 0);
+  if (sock_fd < 0) {
+    sock_fd = INVALID_SOCK_FD;
+    return 0;
+  }
+
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_write_socket, NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_response(SignInstance *inst)
+{
+  struct timespec ts;
+  double delay;
+
+  if (ntohs(inst->request.packet_id) != ntohl(inst->response.packet_id)) {
+    DEBUG_LOG("Invalid response ID");
+    return;
+  }
+
+  if (ntohl(inst->response.op) != SIGNING_SUCCESS) {
+    DEBUG_LOG("Signing failed");
+    return;
+  }
+
+  /* Check if the file descriptor is still valid */
+  if (!NIO_IsServerSocket(inst->local_addr.sock_fd)) {
+    DEBUG_LOG("Invalid NTP socket");
+    return;
+  }
+
+  SCH_GetLastEventTime(NULL, NULL, &ts);
+  delay = UTI_DiffTimespecsToDouble(&ts, &inst->request_ts);
+
+  DEBUG_LOG("Signing succeeded (delay %f)", delay);
+
+  /* Send the signed NTP packet */
+  NIO_SendPacket(&inst->response.signed_packet, &inst->remote_addr, &inst->local_addr,
+                 ntohl(inst->response.length) + sizeof (inst->response.length) -
+                 offsetof(SigndResponse, signed_packet), 0);
+}
+
+/* ================================================== */
+
+static void
+read_write_socket(int sock_fd, int event, void *anything)
+{
+  SignInstance *inst;
+  uint32_t response_length;
+  int s;
+
+  inst = ARR_GetElement(queue, queue_head);
+
+  if (event == SCH_FILE_OUTPUT) {
+    assert(!IS_QUEUE_EMPTY());
+    assert(inst->sent < inst->request_length);
+
+    if (!inst->sent)
+      SCH_GetLastEventTime(NULL, NULL, &inst->request_ts);
+
+    s = SCK_Send(sock_fd, (char *)&inst->request + inst->sent,
+                 inst->request_length - inst->sent, 0);
+
+    if (s < 0) {
+      close_socket();
+      return;
+    }
+
+    inst->sent += s;
+
+    /* Try again later if the request is not complete yet */
+    if (inst->sent < inst->request_length)
+      return;
+
+    /* Disable output and wait for a response */
+    SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 0);
+  }
+
+  if (event == SCH_FILE_INPUT) {
+    if (IS_QUEUE_EMPTY()) {
+        DEBUG_LOG("Unexpected signd response");
+        close_socket();
+        return;
+    }
+
+    assert(inst->received < sizeof (inst->response));
+    s = SCK_Receive(sock_fd, (char *)&inst->response + inst->received,
+                    sizeof (inst->response) - inst->received, 0);
+
+    if (s <= 0) {
+      close_socket();
+      return;
+    }
+
+    inst->received += s;
+
+    if (inst->received < sizeof (inst->response.length))
+      return;
+
+    response_length = ntohl(inst->response.length) + sizeof (inst->response.length);
+
+    if (response_length < offsetof(SigndResponse, signed_packet) ||
+        response_length > sizeof (SigndResponse)) {
+      DEBUG_LOG("Invalid response length");
+      close_socket();
+      return;
+    }
+
+    /* Wait for more data if not complete yet */
+    if (inst->received < response_length)
+      return;
+
+    process_response(inst);
+
+    /* Move the head and enable output for the next packet */
+    queue_head = NEXT_QUEUE_INDEX(queue_head);
+    if (!IS_QUEUE_EMPTY())
+      SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 1);
+  }
+}
+
+/* ================================================== */
+
+void
+NSD_Initialise()
+{
+  sock_fd = INVALID_SOCK_FD;
+  enabled = CNF_GetNtpSigndSocket() && CNF_GetNtpSigndSocket()[0];
+
+  if (!enabled)
+    return;
+
+  queue = ARR_CreateInstance(sizeof (SignInstance));
+  ARR_SetSize(queue, MAX_QUEUE_LENGTH);
+  queue_head = queue_tail = 0;
+
+  LOG(LOGS_INFO, "MS-SNTP authentication enabled");
+}
+
+/* ================================================== */
+
+void
+NSD_Finalise()
+{
+  if (!enabled)
+    return;
+  if (sock_fd != INVALID_SOCK_FD)
+    close_socket();
+  ARR_DestroyInstance(queue);
+}
+
+/* ================================================== */
+
+int
+NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                      NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
+{
+  SignInstance *inst;
+
+  if (!enabled) {
+    DEBUG_LOG("signd disabled");
+    return 0;
+  }
+
+  if (queue_head == NEXT_QUEUE_INDEX(queue_tail)) {
+    DEBUG_LOG("signd queue full");
+    return 0;
+  }
+
+  if (info->length != NTP_HEADER_LENGTH) {
+    DEBUG_LOG("Invalid packet length");
+    return 0;
+  }
+
+  if (!open_socket())
+    return 0;
+
+  inst = ARR_GetElement(queue, queue_tail);
+  inst->remote_addr = *remote_addr;
+  inst->local_addr = *local_addr;
+  inst->sent = 0;
+  inst->received = 0;
+  inst->request_length = offsetof(SigndRequest, packet_to_sign) + info->length;
+
+  /* The length field doesn't include itself */
+  inst->request.length = htonl(inst->request_length - sizeof (inst->request.length));
+  inst->request.version = htonl(SIGND_VERSION);
+  inst->request.op = htonl(SIGN_TO_CLIENT);
+  inst->request.packet_id = htons(queue_tail);
+  inst->request._pad = 0;
+  inst->request.key_id = htonl(key_id);
+
+  memcpy(&inst->request.packet_to_sign, packet, info->length);
+
+  /* Enable output if there was no pending request */
+  if (IS_QUEUE_EMPTY())
+    SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 1);
+
+  queue_tail = NEXT_QUEUE_INDEX(queue_tail);
+
+  DEBUG_LOG("Packet added to signd queue (%u:%u)", queue_head, queue_tail);
+
+  return 1;
+}
diff --git a/ntp_signd.h b/ntp_signd.h
new file mode 100644
index 0000000..d333c9a
--- /dev/null
+++ b/ntp_signd.h
@@ -0,0 +1,42 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for MS-SNTP authentication via Samba (ntp_signd) */
+
+#ifndef GOT_NTP_SIGND_H
+#define GOT_NTP_SIGND_H
+
+#include "addressing.h"
+#include "ntp.h"
+
+/* Initialisation function */
+extern void NSD_Initialise(void);
+
+/* Finalisation function */
+extern void NSD_Finalise(void);
+
+/* Function to sign an NTP packet and send it */
+extern int NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                                 NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr);
+
+#endif
diff --git a/ntp_sources.c b/ntp_sources.c
new file mode 100644
index 0000000..d46c211
--- /dev/null
+++ b/ntp_sources.c
@@ -0,0 +1,1433 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2012, 2014, 2016, 2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions which manage the pool of NTP sources that we are currently
+  a client of or peering with.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "util.h"
+#include "logging.h"
+#include "local.h"
+#include "memory.h"
+#include "nameserv_async.h"
+#include "privops.h"
+#include "sched.h"
+
+/* ================================================== */
+
+/* Maximum number of sources */
+#define MAX_SOURCES 65536
+
+/* Record type private to this file, used to store information about
+   particular sources */
+typedef struct {
+  NTP_Remote_Address *remote_addr; /* The address of this source, non-NULL
+                                      means this slot in table is in use
+                                      (an IPADDR_ID address means the address
+                                      is not resolved yet) */
+  NCR_Instance data;            /* Data for the protocol engine for this source */
+  char *name;                   /* Name of the source as it was specified
+                                   (may be an IP address) */
+  int pool_id;                  /* ID of the pool from which was this source
+                                   added or INVALID_POOL */
+  int tentative;                /* Flag indicating there was no valid response
+                                   received from the source yet */
+  uint32_t conf_id;             /* Configuration ID, which can be shared with
+                                   different sources in case of a pool */
+} SourceRecord;
+
+/* Hash table of SourceRecord, its size is a power of two and it's never
+   more than half full */
+static ARR_Instance records;
+
+/* Number of sources in the hash table */
+static int n_sources;
+
+/* Flag indicating new sources will be started automatically when added */
+static int auto_start_sources = 0;
+
+/* Flag indicating a record is currently being modified */
+static int record_lock;
+
+/* Last assigned address ID */
+static uint32_t last_address_id = 0;
+
+/* Last assigned configuration ID */
+static uint32_t last_conf_id = 0;
+
+/* Source scheduled for name resolving (first resolving or replacement) */
+struct UnresolvedSource {
+  /* Current address of the source (IPADDR_ID is used for a single source
+     with unknown address and IPADDR_UNSPEC for a pool of sources) */
+  NTP_Remote_Address address;
+  /* ID of the pool if not a single source */
+  int pool_id;
+  /* Name to be resolved */
+  char *name;
+  /* Flag indicating addresses should be used in a random order */
+  int random_order;
+  /* Next unresolved source in the list */
+  struct UnresolvedSource *next;
+};
+
+#define RESOLVE_INTERVAL_UNIT 7
+#define MIN_RESOLVE_INTERVAL 2
+#define MAX_RESOLVE_INTERVAL 9
+#define MIN_REPLACEMENT_INTERVAL 8
+
+static struct UnresolvedSource *unresolved_sources = NULL;
+static int resolving_interval = 0;
+static int resolving_restart = 0;
+static SCH_TimeoutID resolving_id;
+static struct UnresolvedSource *resolving_source = NULL;
+static NSR_SourceResolvingEndHandler resolving_end_handler = NULL;
+
+#define MAX_POOL_SOURCES 16
+#define INVALID_POOL (-1)
+
+/* Pool of sources with the same name */
+struct SourcePool {
+  /* Number of all sources from the pool */
+  int sources;
+  /* Number of sources with unresolved address */
+  int unresolved_sources;
+  /* Number of non-tentative sources */
+  int confirmed_sources;
+  /* Maximum number of confirmed sources */
+  int max_sources;
+};
+
+/* Array of SourcePool (indexed by their ID) */
+static ARR_Instance pools;
+
+/* Requested update of a source's address */
+struct AddressUpdate {
+  NTP_Remote_Address old_address;
+  NTP_Remote_Address new_address;
+};
+
+/* Update saved when record_lock is true */
+static struct AddressUpdate saved_address_update;
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void resolve_sources(void);
+static void rehash_records(void);
+static void handle_saved_address_update(void);
+static void clean_source_record(SourceRecord *record);
+static void remove_pool_sources(int pool_id, int tentative, int unresolved);
+static void remove_unresolved_source(struct UnresolvedSource *us);
+
+static void
+slew_sources(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *anything);
+
+/* ================================================== */
+
+/* Flag indicating whether module is initialised */
+static int initialised = 0;
+
+/* ================================================== */
+
+static SourceRecord *
+get_record(unsigned index)
+{
+  return (SourceRecord *)ARR_GetElement(records, index);
+}
+
+/* ================================================== */
+
+static struct SourcePool *
+get_pool(unsigned index)
+{
+  return (struct SourcePool *)ARR_GetElement(pools, index);
+}
+
+/* ================================================== */
+
+void
+NSR_Initialise(void)
+{
+  n_sources = 0;
+  initialised = 1;
+
+  records = ARR_CreateInstance(sizeof (SourceRecord));
+  rehash_records();
+
+  pools = ARR_CreateInstance(sizeof (struct SourcePool));
+
+  LCL_AddParameterChangeHandler(slew_sources, NULL);
+}
+
+/* ================================================== */
+
+void
+NSR_Finalise(void)
+{
+  NSR_RemoveAllSources();
+
+  LCL_RemoveParameterChangeHandler(slew_sources, NULL);
+
+  ARR_DestroyInstance(records);
+  ARR_DestroyInstance(pools);
+
+  while (unresolved_sources)
+    remove_unresolved_source(unresolved_sources);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+/* Find a slot matching an IP address.  It is assumed that there can
+   only ever be one record for a particular IP address. */
+
+static int
+find_slot(IPAddr *ip_addr, int *slot)
+{
+  SourceRecord *record;
+  uint32_t hash;
+  unsigned int i, size;
+
+  size = ARR_GetSize(records);
+
+  *slot = 0;
+  
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+    case IPADDR_ID:
+      break;
+    default:
+      return 0;
+  }
+
+  hash = UTI_IPToHash(ip_addr);
+
+  for (i = 0; i < size / 2; i++) {
+    /* Use quadratic probing */
+    *slot = (hash + (i + i * i) / 2) % size;
+    record = get_record(*slot);
+
+    if (!record->remote_addr)
+      break;
+
+    if (UTI_CompareIPs(&record->remote_addr->ip_addr, ip_addr, NULL) == 0)
+      return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+/* Find a slot matching an IP address and port. The function returns:
+   0 => IP not matched, empty slot returned if a valid address was provided
+   1 => Only IP matched, port doesn't match
+   2 => Both IP and port matched. */
+
+static int
+find_slot2(NTP_Remote_Address *remote_addr, int *slot)
+{
+  if (!find_slot(&remote_addr->ip_addr, slot))
+    return 0;
+
+  return get_record(*slot)->remote_addr->port == remote_addr->port ? 2 : 1;
+}
+
+/* ================================================== */
+/* Check if hash table of given size is sufficient to contain sources */
+
+static int
+check_hashtable_size(unsigned int sources, unsigned int size)
+{
+  return sources * 2 <= size;
+}
+
+/* ================================================== */
+
+static void
+rehash_records(void)
+{
+  SourceRecord *temp_records;
+  unsigned int i, old_size, new_size;
+  int slot;
+
+  assert(!record_lock);
+
+  old_size = ARR_GetSize(records);
+
+  temp_records = MallocArray(SourceRecord, old_size);
+  memcpy(temp_records, ARR_GetElements(records), old_size * sizeof (SourceRecord));
+
+  /* The size of the hash table is always a power of two */
+  for (new_size = 1; !check_hashtable_size(n_sources, new_size); new_size *= 2)
+    ;
+
+  ARR_SetSize(records, new_size);
+
+  for (i = 0; i < new_size; i++)
+    get_record(i)->remote_addr = NULL;
+
+  for (i = 0; i < old_size; i++) {
+    if (!temp_records[i].remote_addr)
+      continue;
+
+    if (find_slot2(temp_records[i].remote_addr, &slot) != 0)
+      assert(0);
+
+    *get_record(slot) = temp_records[i];
+  }
+
+  Free(temp_records);
+}
+
+/* ================================================== */
+
+/* Procedure to add a new source */
+static NSR_Status
+add_source(NTP_Remote_Address *remote_addr, char *name, NTP_Source_Type type,
+           SourceParameters *params, int pool_id, uint32_t conf_id)
+{
+  SourceRecord *record;
+  int slot;
+
+  assert(initialised);
+
+  /* Find empty bin & check that we don't have the address already */
+  if (find_slot2(remote_addr, &slot) != 0) {
+    return NSR_AlreadyInUse;
+  } else if (!name && !UTI_IsIPReal(&remote_addr->ip_addr)) {
+    /* Name is required for non-real addresses */
+    return NSR_InvalidName;
+  } else if (n_sources >= MAX_SOURCES) {
+    return NSR_TooManySources;
+  } else {
+    if (remote_addr->ip_addr.family != IPADDR_INET4 &&
+        remote_addr->ip_addr.family != IPADDR_INET6 &&
+        remote_addr->ip_addr.family != IPADDR_ID) {
+      return NSR_InvalidAF;
+    } else {
+      n_sources++;
+
+      if (!check_hashtable_size(n_sources, ARR_GetSize(records))) {
+        rehash_records();
+        if (find_slot2(remote_addr, &slot) != 0)
+          assert(0);
+      }
+
+      assert(!record_lock);
+      record_lock = 1;
+
+      record = get_record(slot);
+      record->name = Strdup(name ? name : UTI_IPToString(&remote_addr->ip_addr));
+      record->data = NCR_CreateInstance(remote_addr, type, params, record->name);
+      record->remote_addr = NCR_GetRemoteAddress(record->data);
+      record->pool_id = pool_id;
+      record->tentative = 1;
+      record->conf_id = conf_id;
+
+      record_lock = 0;
+
+      if (record->pool_id != INVALID_POOL) {
+        get_pool(record->pool_id)->sources++;
+        if (!UTI_IsIPReal(&remote_addr->ip_addr))
+          get_pool(record->pool_id)->unresolved_sources++;
+      }
+
+      if (auto_start_sources && UTI_IsIPReal(&remote_addr->ip_addr))
+        NCR_StartInstance(record->data);
+
+      /* The new instance is allowed to change its address immediately */
+      handle_saved_address_update();
+
+      return NSR_Success;
+    }
+  }
+}
+
+/* ================================================== */
+
+static NSR_Status
+change_source_address(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr,
+                      int replacement)
+{
+  int slot1, slot2, found;
+  SourceRecord *record;
+  LOG_Severity severity;
+  char *name;
+
+  found = find_slot2(old_addr, &slot1);
+  if (found != 2)
+    return NSR_NoSuchSource;
+
+  /* Make sure there is no other source using the new address (with the same
+     or different port), but allow a source to have its port changed */
+  found = find_slot2(new_addr, &slot2);
+  if (found == 2 || (found != 0 && slot1 != slot2))
+    return NSR_AlreadyInUse;
+
+  assert(!record_lock);
+  record_lock = 1;
+
+  record = get_record(slot1);
+  NCR_ChangeRemoteAddress(record->data, new_addr, !replacement);
+
+  if (record->remote_addr != NCR_GetRemoteAddress(record->data) ||
+      UTI_CompareIPs(&record->remote_addr->ip_addr, &new_addr->ip_addr, NULL) != 0)
+    assert(0);
+
+  if (!UTI_IsIPReal(&old_addr->ip_addr) && UTI_IsIPReal(&new_addr->ip_addr)) {
+    if (auto_start_sources)
+      NCR_StartInstance(record->data);
+    if (record->pool_id != INVALID_POOL)
+      get_pool(record->pool_id)->unresolved_sources--;
+  }
+
+  if (!record->tentative) {
+    record->tentative = 1;
+
+    if (record->pool_id != INVALID_POOL)
+      get_pool(record->pool_id)->confirmed_sources--;
+  }
+
+  record_lock = 0;
+
+  name = record->name;
+  severity = UTI_IsIPReal(&old_addr->ip_addr) ? LOGS_INFO : LOGS_DEBUG;
+
+  if (found == 0) {
+    /* The hash table must be rebuilt for the changed address */
+    rehash_records();
+
+    LOG(severity, "Source %s %s %s (%s)", UTI_IPToString(&old_addr->ip_addr),
+        replacement ? "replaced with" : "changed to",
+        UTI_IPToString(&new_addr->ip_addr), name);
+  } else {
+    LOG(severity, "Source %s (%s) changed port to %d",
+        UTI_IPToString(&new_addr->ip_addr), name, new_addr->port);
+  }
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+static void
+handle_saved_address_update(void)
+{
+  if (!UTI_IsIPReal(&saved_address_update.old_address.ip_addr))
+    return;
+
+  if (change_source_address(&saved_address_update.old_address,
+                            &saved_address_update.new_address, 0) != NSR_Success)
+    /* This is expected to happen only if the old address is wrong */
+    LOG(LOGS_ERR, "Could not change %s to %s",
+        UTI_IPSockAddrToString(&saved_address_update.old_address),
+        UTI_IPSockAddrToString(&saved_address_update.new_address));
+
+  saved_address_update.old_address.ip_addr.family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+static int
+replace_source_connectable(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr)
+{
+  if (!NIO_IsServerConnectable(new_addr)) {
+    DEBUG_LOG("%s not connectable", UTI_IPToString(&new_addr->ip_addr));
+    return 0;
+  }
+
+  if (change_source_address(old_addr, new_addr, 1) == NSR_AlreadyInUse)
+    return 0;
+
+  handle_saved_address_update();
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_resolved_name(struct UnresolvedSource *us, IPAddr *ip_addrs, int n_addrs)
+{
+  NTP_Remote_Address old_addr, new_addr;
+  SourceRecord *record;
+  unsigned short first = 0;
+  int i, j;
+
+  if (us->random_order)
+    UTI_GetRandomBytes(&first, sizeof (first));
+
+  for (i = 0; i < n_addrs; i++) {
+    new_addr.ip_addr = ip_addrs[((unsigned int)i + first) % n_addrs];
+
+    DEBUG_LOG("(%d) %s", i + 1, UTI_IPToString(&new_addr.ip_addr));
+
+    if (us->pool_id != INVALID_POOL) {
+      /* In the pool resolving mode, try to replace a source from
+         the pool which does not have a real address yet */
+      for (j = 0; j < ARR_GetSize(records); j++) {
+        record = get_record(j);
+        if (!record->remote_addr || record->pool_id != us->pool_id ||
+            UTI_IsIPReal(&record->remote_addr->ip_addr))
+          continue;
+        old_addr = *record->remote_addr;
+        new_addr.port = old_addr.port;
+        if (replace_source_connectable(&old_addr, &new_addr))
+          ;
+        break;
+      }
+    } else {
+      new_addr.port = us->address.port;
+      if (replace_source_connectable(&us->address, &new_addr))
+        break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+is_resolved(struct UnresolvedSource *us)
+{
+  int slot;
+
+  if (us->pool_id != INVALID_POOL) {
+    return get_pool(us->pool_id)->unresolved_sources <= 0;
+  } else {
+    /* If the address is no longer present, it was removed or replaced
+       (i.e. resolved) */
+    return find_slot2(&us->address, &slot) == 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+resolve_sources_timeout(void *arg)
+{
+  resolving_id = 0;
+  resolve_sources();
+}
+
+/* ================================================== */
+
+static void
+name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *anything)
+{
+  struct UnresolvedSource *us, *next;
+
+  us = (struct UnresolvedSource *)anything;
+
+  assert(us == resolving_source);
+  assert(resolving_id == 0);
+
+  DEBUG_LOG("%s resolved to %d addrs", us->name, n_addrs);
+
+  switch (status) {
+    case DNS_TryAgain:
+      break;
+    case DNS_Success:
+      process_resolved_name(us, ip_addrs, n_addrs);
+      break;
+    case DNS_Failure:
+      LOG(LOGS_WARN, "Invalid host %s", us->name);
+      break;
+    default:
+      assert(0);
+  }
+
+  next = us->next;
+
+  /* Don't repeat the resolving if it (permanently) failed, it was a
+     replacement of a real address, or all addresses are already resolved */
+  if (status == DNS_Failure || UTI_IsIPReal(&us->address.ip_addr) || is_resolved(us))
+    remove_unresolved_source(us);
+
+  /* If a restart was requested and this was the last source in the list,
+     start with the first source again (if there still is one) */
+  if (!next && resolving_restart) {
+    next = unresolved_sources;
+    resolving_restart = 0;
+  }
+
+  resolving_source = next;
+
+  if (next) {
+    /* Continue with the next source in the list */
+    DEBUG_LOG("resolving %s", next->name);
+    DNS_Name2IPAddressAsync(next->name, name_resolve_handler, next);
+  } else {
+    /* This was the last source in the list. If some sources couldn't
+       be resolved, try again in exponentially increasing interval. */
+    if (unresolved_sources) {
+      resolving_interval = CLAMP(MIN_RESOLVE_INTERVAL, resolving_interval + 1,
+                                 MAX_RESOLVE_INTERVAL);
+      resolving_id = SCH_AddTimeoutByDelay(RESOLVE_INTERVAL_UNIT * (1 << resolving_interval),
+                                           resolve_sources_timeout, NULL);
+    } else {
+      resolving_interval = 0;
+    }
+
+    /* This round of resolving is done */
+    if (resolving_end_handler)
+      (resolving_end_handler)();
+  }
+}
+
+/* ================================================== */
+
+static void
+resolve_sources(void)
+{
+  struct UnresolvedSource *us, *next, *i;
+
+  assert(!resolving_source);
+
+  /* Remove sources that don't need to be resolved anymore */
+  for (i = unresolved_sources; i; i = next) {
+    next = i->next;
+    if (is_resolved(i))
+      remove_unresolved_source(i);
+  }
+
+  if (!unresolved_sources)
+    return;
+
+  PRV_ReloadDNS();
+
+  /* Start with the first source in the list, name_resolve_handler
+     will iterate over the rest */
+  us = unresolved_sources;
+
+  resolving_source = us;
+  DEBUG_LOG("resolving %s", us->name);
+  DNS_Name2IPAddressAsync(us->name, name_resolve_handler, us);
+}
+
+/* ================================================== */
+
+static void
+append_unresolved_source(struct UnresolvedSource *us)
+{
+  struct UnresolvedSource **i;
+
+  for (i = &unresolved_sources; *i; i = &(*i)->next)
+    ;
+  *i = us;
+  us->next = NULL;
+}
+
+/* ================================================== */
+
+static void
+remove_unresolved_source(struct UnresolvedSource *us)
+{
+  struct UnresolvedSource **i;
+
+  for (i = &unresolved_sources; *i; i = &(*i)->next) {
+    if (*i == us) {
+      *i = us->next;
+      Free(us->name);
+      Free(us);
+      break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int get_unused_pool_id(void)
+{
+  struct UnresolvedSource *us;
+  int i;
+
+  for (i = 0; i < ARR_GetSize(pools); i++) {
+    if (get_pool(i)->sources > 0)
+      continue;
+
+    /* Make sure there is no name waiting to be resolved using this pool */
+    for (us = unresolved_sources; us; us = us->next) {
+      if (us->pool_id == i)
+        break;
+    }
+    if (us)
+      continue;
+
+    return i;
+  }
+
+  return INVALID_POOL;
+}
+
+/* ================================================== */
+
+static uint32_t
+get_next_conf_id(uint32_t *conf_id)
+{
+  last_conf_id++;
+
+  if (conf_id)
+    *conf_id = last_conf_id;
+
+  return last_conf_id;
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+              SourceParameters *params, uint32_t *conf_id)
+{
+  return add_source(remote_addr, NULL, type, params, INVALID_POOL,
+                    get_next_conf_id(conf_id));
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                    SourceParameters *params, uint32_t *conf_id)
+{
+  struct UnresolvedSource *us;
+  struct SourcePool *sp;
+  NTP_Remote_Address remote_addr;
+  int i, new_sources, pool_id;
+  uint32_t cid;
+
+  /* If the name is an IP address, add the source with the address directly */
+  if (UTI_StringToIP(name, &remote_addr.ip_addr)) {
+    remote_addr.port = port;
+    return add_source(&remote_addr, name, type, params, INVALID_POOL,
+                      get_next_conf_id(conf_id));
+  }
+
+  /* Make sure the name is at least printable and has no spaces */
+  for (i = 0; name[i] != '\0'; i++) {
+    if (!isgraph((unsigned char)name[i]))
+      return NSR_InvalidName;
+  }
+
+  us = MallocNew(struct UnresolvedSource);
+  us->name = Strdup(name);
+  us->random_order = 0;
+
+  remote_addr.ip_addr.family = IPADDR_ID;
+  remote_addr.ip_addr.addr.id = ++last_address_id;
+  remote_addr.port = port;
+
+  if (!pool) {
+    us->pool_id = INVALID_POOL;
+    us->address = remote_addr;
+    new_sources = 1;
+  } else {
+    pool_id = get_unused_pool_id();
+    if (pool_id != INVALID_POOL) {
+      sp = get_pool(pool_id);
+    } else {
+      sp = ARR_GetNewElement(pools);
+      pool_id = ARR_GetSize(pools) - 1;
+    }
+
+    sp->sources = 0;
+    sp->unresolved_sources = 0;
+    sp->confirmed_sources = 0;
+    sp->max_sources = CLAMP(1, params->max_sources, MAX_POOL_SOURCES);
+    us->pool_id = pool_id;
+    us->address.ip_addr.family = IPADDR_UNSPEC;
+    new_sources = MIN(2 * sp->max_sources, MAX_POOL_SOURCES);
+  }
+
+  append_unresolved_source(us);
+
+  cid = get_next_conf_id(conf_id);
+
+  for (i = 0; i < new_sources; i++) {
+    if (i > 0)
+      remote_addr.ip_addr.addr.id = ++last_address_id;
+    if (add_source(&remote_addr, name, type, params, us->pool_id, cid) != NSR_Success)
+      return NSR_TooManySources;
+  }
+
+  return NSR_UnresolvedName;
+}
+
+/* ================================================== */
+
+void
+NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler)
+{
+  resolving_end_handler = handler;
+}
+
+/* ================================================== */
+
+void
+NSR_ResolveSources(void)
+{
+  /* Try to resolve unresolved sources now */
+  if (unresolved_sources) {
+    /* Allow only one resolving to be running at a time */
+    if (!resolving_source) {
+      if (resolving_id != 0) {
+        SCH_RemoveTimeout(resolving_id);
+        resolving_id = 0;
+        resolving_interval--;
+      }
+      resolve_sources();
+    } else {
+      /* Try again as soon as the current resolving ends */
+      resolving_restart = 1;
+    }
+  } else {
+    /* No unresolved sources, we are done */
+    if (resolving_end_handler)
+      (resolving_end_handler)();
+  }
+}
+
+/* ================================================== */
+
+void NSR_StartSources(void)
+{
+  NTP_Remote_Address *addr;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    addr = get_record(i)->remote_addr;
+    if (!addr || !UTI_IsIPReal(&addr->ip_addr))
+      continue;
+    NCR_StartInstance(get_record(i)->data);
+  }
+}
+
+/* ================================================== */
+
+void NSR_AutoStartSources(void)
+{
+  auto_start_sources = 1;
+}
+
+/* ================================================== */
+
+static void
+clean_source_record(SourceRecord *record)
+{
+  assert(record->remote_addr);
+
+  if (record->pool_id != INVALID_POOL) {
+    struct SourcePool *pool = get_pool(record->pool_id);
+
+    pool->sources--;
+    if (!UTI_IsIPReal(&record->remote_addr->ip_addr))
+      pool->unresolved_sources--;
+    if (!record->tentative)
+      pool->confirmed_sources--;
+    if (pool->max_sources > pool->sources)
+      pool->max_sources = pool->sources;
+  }
+
+  record->remote_addr = NULL;
+  NCR_DestroyInstance(record->data);
+  Free(record->name);
+
+  n_sources--;
+}
+
+/* ================================================== */
+
+/* Procedure to remove a source.  We don't bother whether the port
+   address is matched - we're only interested in removing a record for
+   the right IP address. */
+NSR_Status
+NSR_RemoveSource(IPAddr *address)
+{
+  int slot;
+
+  assert(initialised);
+
+  if (find_slot(address, &slot) == 0)
+    return NSR_NoSuchSource;
+
+  clean_source_record(get_record(slot));
+
+  /* Rehash the table to make sure there are no broken probe sequences.
+     This is costly, but it's not expected to happen frequently. */
+
+  rehash_records();
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+void
+NSR_RemoveSourcesById(uint32_t conf_id)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr || record->conf_id != conf_id)
+      continue;
+    clean_source_record(record);
+  }
+
+  rehash_records();
+}
+
+/* ================================================== */
+
+void
+NSR_RemoveAllSources(void)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+    clean_source_record(record);
+  }
+
+  rehash_records();
+}
+
+/* ================================================== */
+
+static void
+resolve_source_replacement(SourceRecord *record)
+{
+  struct UnresolvedSource *us;
+
+  DEBUG_LOG("trying to replace %s (%s)",
+            UTI_IPToString(&record->remote_addr->ip_addr), record->name);
+
+  us = MallocNew(struct UnresolvedSource);
+  us->name = Strdup(record->name);
+  /* If there never was a valid reply from this source (e.g. it was a bad
+     replacement), ignore the order of addresses from the resolver to not get
+     stuck to a pair of addresses if the order doesn't change, or a group of
+     IPv4/IPv6 addresses if the resolver prefers inaccessible IP family */
+  us->random_order = record->tentative;
+  us->pool_id = INVALID_POOL;
+  us->address = *record->remote_addr;
+
+  append_unresolved_source(us);
+  NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+void
+NSR_HandleBadSource(IPAddr *address)
+{
+  static struct timespec last_replacement;
+  struct timespec now;
+  SourceRecord *record;
+  IPAddr ip_addr;
+  double diff;
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return;
+
+  record = get_record(slot);
+
+  /* Don't try to replace a source specified by an IP address unless the
+     address changed since the source was added (e.g. by NTS-KE) */
+  if (UTI_StringToIP(record->name, &ip_addr) &&
+      UTI_CompareIPs(&record->remote_addr->ip_addr, &ip_addr, NULL) == 0)
+    return;
+
+  /* Don't resolve names too frequently */
+  SCH_GetLastEventTime(NULL, NULL, &now);
+  diff = UTI_DiffTimespecsToDouble(&now, &last_replacement);
+  if (fabs(diff) < RESOLVE_INTERVAL_UNIT * (1 << MIN_REPLACEMENT_INTERVAL)) {
+    DEBUG_LOG("replacement postponed");
+    return;
+  }
+  last_replacement = now;
+
+  resolve_source_replacement(record);
+}
+
+/* ================================================== */
+
+void
+NSR_RefreshAddresses(void)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+
+    resolve_source_replacement(record);
+  }
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_UpdateSourceNtpAddress(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr)
+{
+  int slot;
+
+  if (!UTI_IsIPReal(&old_addr->ip_addr) || !UTI_IsIPReal(&new_addr->ip_addr))
+    return NSR_InvalidAF;
+
+  if (UTI_CompareIPs(&old_addr->ip_addr, &new_addr->ip_addr, NULL) != 0 &&
+      find_slot(&new_addr->ip_addr, &slot))
+    return NSR_AlreadyInUse;
+
+  /* If a record is being modified (e.g. by change_source_address(), or the
+     source is just being created), postpone the change to avoid corruption */
+
+  if (!record_lock)
+    return change_source_address(old_addr, new_addr, 0);
+
+  if (UTI_IsIPReal(&saved_address_update.old_address.ip_addr))
+    return NSR_TooManySources;
+
+  saved_address_update.old_address = *old_addr;
+  saved_address_update.new_address = *new_addr;
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+static void remove_pool_sources(int pool_id, int tentative, int unresolved)
+{
+  SourceRecord *record;
+  unsigned int i, removed;
+
+  for (i = removed = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+
+    if (!record->remote_addr || record->pool_id != pool_id)
+      continue;
+
+    if ((tentative && !record->tentative) ||
+        (unresolved && UTI_IsIPReal(&record->remote_addr->ip_addr)))
+      continue;
+
+    DEBUG_LOG("removing %ssource %s", tentative ? "tentative " : "",
+              UTI_IPToString(&record->remote_addr->ip_addr));
+
+    clean_source_record(record);
+    removed++;
+  }
+
+  if (removed)
+    rehash_records();
+}
+
+/* ================================================== */
+
+uint32_t
+NSR_GetLocalRefid(IPAddr *address)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  return NCR_GetLocalRefid(get_record(slot)->data);
+}
+
+/* ================================================== */
+
+char *
+NSR_GetName(IPAddr *address)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return NULL;
+
+  return get_record(slot)->name;
+}
+
+/* ================================================== */
+
+/* This routine is called by ntp_io when a new packet arrives off the network,
+   possibly with an authentication tail */
+void
+NSR_ProcessRx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+              NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  SourceRecord *record;
+  struct SourcePool *pool;
+  int slot;
+
+  assert(initialised);
+
+  /* Avoid unnecessary lookup if the packet cannot be a response from our
+     source.  Otherwise, it must match both IP address and port number. */
+  if (NTP_LVM_TO_MODE(message->lvm) != MODE_CLIENT &&
+      find_slot2(remote_addr, &slot) == 2) {
+    record = get_record(slot);
+
+    if (!NCR_ProcessRxKnown(record->data, local_addr, rx_ts, message, length))
+      return;
+
+    if (record->tentative) {
+      /* This was the first good reply from the source */
+      record->tentative = 0;
+
+      if (record->pool_id != INVALID_POOL) {
+        pool = get_pool(record->pool_id);
+        pool->confirmed_sources++;
+
+        DEBUG_LOG("pool %s has %d confirmed sources", record->name, pool->confirmed_sources);
+
+        /* If the number of sources from the pool reached the configured
+           maximum, remove the remaining tentative sources */
+        if (pool->confirmed_sources >= pool->max_sources)
+          remove_pool_sources(record->pool_id, 1, 0);
+      }
+    }
+  } else {
+    NCR_ProcessRxUnknown(remote_addr, local_addr, rx_ts, message, length);
+  }
+}
+
+/* ================================================== */
+
+void
+NSR_ProcessTx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+              NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  SourceRecord *record;
+  int slot;
+
+  /* Avoid unnecessary lookup if the packet cannot be a request to our
+     source.  Otherwise, it must match both IP address and port number. */
+  if (NTP_LVM_TO_MODE(message->lvm) != MODE_SERVER &&
+      find_slot2(remote_addr, &slot) == 2) {
+    record = get_record(slot);
+    NCR_ProcessTxKnown(record->data, local_addr, tx_ts, message, length);
+  } else {
+    NCR_ProcessTxUnknown(remote_addr, local_addr, tx_ts, message, length);
+  }
+}
+
+/* ================================================== */
+
+static void
+slew_sources(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *anything)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      if (change_type == LCL_ChangeUnknownStep) {
+        NCR_ResetInstance(record->data);
+        NCR_ResetPoll(record->data);
+      } else {
+        NCR_SlewTimes(record->data, cooked, dfreq, doffset);
+      }
+    }
+  }
+}
+
+/* ================================================== */
+
+int
+NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity)
+{
+  SourceRecord *record, *syncpeer;
+  unsigned int i, any;
+
+  if (connectivity != SRC_OFFLINE)
+    NSR_ResolveSources();
+
+  any = 0;
+  syncpeer = NULL;
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      /* Ignore SRC_MAYBE_ONLINE connectivity change for unspecified unresolved
+         sources as they would always end up in the offline state */
+      if ((address->family == IPADDR_UNSPEC &&
+           (connectivity != SRC_MAYBE_ONLINE || UTI_IsIPReal(&record->remote_addr->ip_addr))) ||
+          !UTI_CompareIPs(&record->remote_addr->ip_addr, address, mask)) {
+        any = 1;
+        if (NCR_IsSyncPeer(record->data)) {
+          syncpeer = record;
+          continue;
+        }
+        NCR_SetConnectivity(record->data, connectivity);
+      }
+    }
+  }
+
+  /* Set the sync peer last to avoid unnecessary reference switching */
+  if (syncpeer)
+    NCR_SetConnectivity(syncpeer->data, connectivity);
+
+  return any;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMinpoll(IPAddr *address, int new_minpoll)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMinpoll(get_record(slot)->data, new_minpoll);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxpoll(get_record(slot)->data, new_maxpoll);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelay(get_record(slot)->data, new_max_delay);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelayratio(get_record(slot)->data, new_max_delay_ratio);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_dev_ratio)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelaydevratio(get_record(slot)->data, new_max_delay_dev_ratio);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMinstratum(get_record(slot)->data, new_min_stratum);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyPolltarget(IPAddr *address, int new_poll_target)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyPolltarget(get_record(slot)->data, new_poll_target);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples,
+                        IPAddr *mask, IPAddr *address)
+{
+  SourceRecord *record;
+  unsigned int i;
+  int any;
+
+  any = 0;
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      if (address->family == IPADDR_UNSPEC ||
+          !UTI_CompareIPs(&record->remote_addr->ip_addr, address, mask)) {
+        any = 1;
+        NCR_InitiateSampleBurst(record->data, n_good_samples, n_total_samples);
+      }
+    }
+  }
+
+  return any;
+
+}
+
+/* ================================================== */
+/* The ip address is assumed to be completed on input, that is how we
+   identify the source record. */
+
+void
+NSR_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  int slot;
+
+  if (find_slot(&report->ip_addr, &slot)) {
+    NCR_ReportSource(get_record(slot)->data, report, now);
+  } else {
+    report->poll = 0;
+    report->latest_meas_ago = 0;
+  }
+}
+
+/* ================================================== */
+
+int
+NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_GetAuthReport(get_record(slot)->data, report);
+  return 1;
+}
+
+/* ================================================== */
+/* The ip address is assumed to be completed on input, that is how we
+   identify the source record. */
+
+int
+NSR_GetNTPReport(RPT_NTPReport *report)
+{
+  int slot;
+
+  if (!find_slot(&report->remote_addr, &slot))
+    return 0;
+
+  NCR_GetNTPReport(get_record(slot)->data, report);
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NSR_GetActivityReport(RPT_ActivityReport *report)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  report->online = 0;
+  report->offline = 0;
+  report->burst_online = 0;
+  report->burst_offline = 0;
+  report->unresolved = 0;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+
+    if (!UTI_IsIPReal(&record->remote_addr->ip_addr)) {
+      report->unresolved++;
+    } else {
+      NCR_IncrementActivityCounters(record->data, &report->online, &report->offline,
+                                    &report->burst_online, &report->burst_offline);
+    }
+  }
+}
+
+/* ================================================== */
+
+void
+NSR_DumpAuthData(void)
+{
+  SourceRecord *record;
+  int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+    NCR_DumpAuthData(record->data);
+  }
+}
diff --git a/ntp_sources.h b/ntp_sources.h
new file mode 100644
index 0000000..ba3b9c4
--- /dev/null
+++ b/ntp_sources.h
@@ -0,0 +1,152 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for the part of the software that deals with the set of
+  current NTP servers and peers, which can resolve an IP address into
+  a source record for further processing.
+
+  */
+
+#ifndef GOT_NTP_SOURCES_H
+#define GOT_NTP_SOURCES_H
+
+#include "ntp.h"
+#include "addressing.h"
+#include "srcparams.h"
+#include "ntp_core.h"
+#include "reports.h"
+
+/* Status values returned by operations that indirectly result from user
+   input. */
+typedef enum {
+  NSR_Success, /* Operation successful */
+  NSR_NoSuchSource, /* Remove - attempt to remove a source that is not known */
+  NSR_AlreadyInUse, /* AddSource - attempt to add a source that is already known */ 
+  NSR_TooManySources, /* AddSource - too many sources already present */
+  NSR_InvalidAF, /* AddSource - attempt to add a source with invalid address family */
+  NSR_InvalidName, /* AddSourceByName - attempt to add a source with invalid name */
+  NSR_UnresolvedName, /* AddSourceByName - name will be resolved later */
+} NSR_Status;
+
+/* Procedure to add a new server or peer source. */
+extern NSR_Status NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                                SourceParameters *params, uint32_t *conf_id);
+
+/* Procedure to add a new server, peer source, or pool of servers specified by
+   name instead of address.  The name is resolved in exponentially increasing
+   intervals until it succeeds or fails with a non-temporary error.  If the
+   name is an address, it is equivalent to NSR_AddSource(). */
+extern NSR_Status NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                                      SourceParameters *params, uint32_t *conf_id);
+
+/* Function type for handlers to be called back when an attempt
+ * (possibly unsuccessful) to resolve unresolved sources ends */
+typedef void (*NSR_SourceResolvingEndHandler)(void);
+
+/* Set the handler, or NULL to disable the notification */
+extern void NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler);
+
+/* Procedure to start resolving unresolved sources */
+extern void NSR_ResolveSources(void);
+
+/* Procedure to start all sources */
+extern void NSR_StartSources(void);
+
+/* Start new sources automatically */
+extern void NSR_AutoStartSources(void);
+
+/* Procedure to remove a source */
+extern NSR_Status NSR_RemoveSource(IPAddr *address);
+
+/* Procedure to remove all sources matching a configuration ID */
+extern void NSR_RemoveSourcesById(uint32_t conf_id);
+
+/* Procedure to remove all sources */
+extern void NSR_RemoveAllSources(void);
+
+/* Procedure to try to find a replacement for a bad source */
+extern void NSR_HandleBadSource(IPAddr *address);
+
+/* Procedure to resolve all names again */
+extern void NSR_RefreshAddresses(void);
+
+/* Procedure to update the address of a source.  The update may be
+   postponed. */
+extern NSR_Status NSR_UpdateSourceNtpAddress(NTP_Remote_Address *old_addr,
+                                             NTP_Remote_Address *new_addr);
+
+/* Procedure to get local reference ID corresponding to a source */
+extern uint32_t NSR_GetLocalRefid(IPAddr *address);
+
+/* Procedure to get the name of a source as it was specified (it may be
+   an IP address) */
+extern char *NSR_GetName(IPAddr *address);
+
+/* This routine is called by ntp_io when a new packet arrives off the network */
+extern void NSR_ProcessRx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                          NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called by ntp_io when a packet was sent to the network and
+   an accurate transmit timestamp was captured */
+extern void NSR_ProcessTx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                          NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* Initialisation function */
+extern void NSR_Initialise(void);
+
+/* Finalisation function */
+extern void NSR_Finalise(void);
+
+/* This routine is used to indicate that sources whose IP addresses
+   match a particular subnet should be set online or offline.  It returns
+   a flag indicating whether any hosts matched the address. */
+extern int NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity);
+
+extern int NSR_ModifyMinpoll(IPAddr *address, int new_minpoll);
+
+extern int NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll);
+
+extern int NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay);
+
+extern int NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio);
+
+extern int NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_ratio);
+
+extern int NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum);
+
+extern int NSR_ModifyPolltarget(IPAddr *address, int new_poll_target);
+
+extern int NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples, IPAddr *mask, IPAddr *address);
+
+extern void NSR_ReportSource(RPT_SourceReport *report, struct timespec *now);
+
+extern int NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report);
+
+extern int NSR_GetNTPReport(RPT_NTPReport *report);
+
+extern void NSR_GetActivityReport(RPT_ActivityReport *report);
+
+extern void NSR_DumpAuthData(void);
+
+#endif /* GOT_NTP_SOURCES_H */
diff --git a/nts_ke.h b/nts_ke.h
new file mode 100644
index 0000000..e7497af
--- /dev/null
+++ b/nts_ke.h
@@ -0,0 +1,81 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS Key Establishment protocol
+  */
+
+#ifndef GOT_NTS_KE_H
+#define GOT_NTS_KE_H
+
+#include "siv.h"
+
+#define NKE_PORT                        4460
+
+#define NKE_RECORD_CRITICAL_BIT         (1U << 15)
+#define NKE_RECORD_END_OF_MESSAGE       0
+#define NKE_RECORD_NEXT_PROTOCOL        1
+#define NKE_RECORD_ERROR                2
+#define NKE_RECORD_WARNING              3
+#define NKE_RECORD_AEAD_ALGORITHM       4
+#define NKE_RECORD_COOKIE               5
+#define NKE_RECORD_NTPV4_SERVER_NEGOTIATION 6
+#define NKE_RECORD_NTPV4_PORT_NEGOTIATION 7
+
+#define NKE_NEXT_PROTOCOL_NTPV4         0
+
+#define NKE_ERROR_UNRECOGNIZED_CRITICAL_RECORD 0
+#define NKE_ERROR_BAD_REQUEST           1
+#define NKE_ERROR_INTERNAL_SERVER_ERROR 2
+
+#define NKE_ALPN_NAME                   "ntske/1"
+#define NKE_EXPORTER_LABEL              "EXPORTER-network-time-security"
+#define NKE_EXPORTER_CONTEXT_C2S        "\x0\x0\x0\xf\x0"
+#define NKE_EXPORTER_CONTEXT_S2C        "\x0\x0\x0\xf\x1"
+
+#define NKE_MAX_MESSAGE_LENGTH          16384
+#define NKE_MAX_RECORD_BODY_LENGTH      256
+#define NKE_MAX_COOKIE_LENGTH           256
+#define NKE_MAX_COOKIES                 8
+#define NKE_MAX_KEY_LENGTH SIV_MAX_KEY_LENGTH
+
+#define NKE_RETRY_FACTOR2_CONNECT       4
+#define NKE_RETRY_FACTOR2_TLS           10
+#define NKE_MAX_RETRY_INTERVAL2         19
+
+typedef struct {
+  int length;
+  unsigned char key[NKE_MAX_KEY_LENGTH];
+} NKE_Key;
+
+typedef struct {
+  SIV_Algorithm algorithm;
+  NKE_Key c2s;
+  NKE_Key s2c;
+} NKE_Context;
+
+typedef struct {
+  int length;
+  unsigned char cookie[NKE_MAX_COOKIE_LENGTH];
+} NKE_Cookie;
+
+#endif
diff --git a/nts_ke_client.c b/nts_ke_client.c
new file mode 100644
index 0000000..c22b0eb
--- /dev/null
+++ b/nts_ke_client.c
@@ -0,0 +1,442 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE client
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_client.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "nameserv_async.h"
+#include "nts_ke_session.h"
+#include "siv.h"
+#include "socket.h"
+#include "util.h"
+
+#define CLIENT_TIMEOUT 16.0
+
+struct NKC_Instance_Record {
+  char *name;
+  IPSockAddr address;
+  NKSN_Credentials credentials;
+  NKSN_Instance session;
+  int destroying;
+  int got_response;
+  int resolving_name;
+
+  NKE_Context context;
+  NKE_Cookie cookies[NKE_MAX_COOKIES];
+  int num_cookies;
+  char server_name[NKE_MAX_RECORD_BODY_LENGTH + 2];
+  IPSockAddr ntp_address;
+};
+
+/* ================================================== */
+
+static NKSN_Credentials default_credentials = NULL;
+static int default_credentials_refs = 0;
+
+/* ================================================== */
+
+static void
+name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *arg)
+{
+  NKC_Instance inst = arg;
+  int i;
+
+  inst->resolving_name = 0;
+
+  if (inst->destroying) {
+    Free(inst);
+    return;
+  }
+
+  if (status != DNS_Success || n_addrs < 1) {
+    LOG(LOGS_ERR, "Could not resolve NTP server %s from %s", inst->server_name, inst->name);
+    /* Force restart */
+    inst->got_response = 0;
+    return;
+  }
+
+  inst->ntp_address.ip_addr = ip_addrs[0];
+
+  /* Prefer an address in the same family as the NTS-KE server */
+  for (i = 0; i < n_addrs; i++) {
+    DEBUG_LOG("%s resolved to %s", inst->server_name, UTI_IPToString(&ip_addrs[i]));
+    if (ip_addrs[i].family == inst->address.ip_addr.family) {
+      inst->ntp_address.ip_addr = ip_addrs[i];
+      break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+prepare_request(NKC_Instance inst)
+{
+  NKSN_Instance session = inst->session;
+  uint16_t datum;
+
+  NKSN_BeginMessage(session);
+
+  datum = htons(NKE_NEXT_PROTOCOL_NTPV4);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+    return 0;
+
+  datum = htons(AEAD_AES_SIV_CMAC_256);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, &datum, sizeof (datum)))
+    return 0;
+
+  if (!NKSN_EndMessage(session))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_response(NKC_Instance inst)
+{
+  int next_protocol = -1, aead_algorithm = -1, error = 0;
+  int i, critical, type, length;
+  uint16_t data[NKE_MAX_RECORD_BODY_LENGTH / sizeof (uint16_t)];
+
+  assert(NKE_MAX_COOKIE_LENGTH <= NKE_MAX_RECORD_BODY_LENGTH);
+  assert(sizeof (data) % sizeof (uint16_t) == 0);
+  assert(sizeof (uint16_t) == 2);
+
+  inst->num_cookies = 0;
+  inst->ntp_address.ip_addr.family = IPADDR_UNSPEC;
+  inst->ntp_address.port = 0;
+  inst->server_name[0] = '\0';
+
+  while (!error) {
+    if (!NKSN_GetRecord(inst->session, &critical, &type, &length, &data, sizeof (data)))
+      break;
+
+    if (length > sizeof (data)) {
+      DEBUG_LOG("Record too long type=%d length=%d critical=%d", type, length, critical);
+      if (critical)
+        error = 1;
+      continue;
+    }
+
+    switch (type) {
+      case NKE_RECORD_NEXT_PROTOCOL:
+        if (!critical || length != 2 || ntohs(data[0]) != NKE_NEXT_PROTOCOL_NTPV4) {
+          DEBUG_LOG("Unexpected NTS-KE next protocol");
+          error = 1;
+          break;
+        }
+        next_protocol = NKE_NEXT_PROTOCOL_NTPV4;
+        break;
+      case NKE_RECORD_AEAD_ALGORITHM:
+        if (length != 2 || ntohs(data[0]) != AEAD_AES_SIV_CMAC_256) {
+          DEBUG_LOG("Unexpected NTS-KE AEAD algorithm");
+          error = 1;
+          break;
+        }
+        aead_algorithm = AEAD_AES_SIV_CMAC_256;
+        inst->context.algorithm = aead_algorithm;
+        break;
+      case NKE_RECORD_ERROR:
+        if (length == 2)
+          DEBUG_LOG("NTS-KE error %d", ntohs(data[0]));
+        error = 1;
+        break;
+      case NKE_RECORD_WARNING:
+        if (length == 2)
+          DEBUG_LOG("NTS-KE warning %d", ntohs(data[0]));
+        error = 1;
+        break;
+      case NKE_RECORD_COOKIE:
+        DEBUG_LOG("Got cookie length=%d", length);
+
+        if (length < 1 || length > NKE_MAX_COOKIE_LENGTH || length % 4 != 0 ||
+            inst->num_cookies >= NKE_MAX_COOKIES) {
+          DEBUG_LOG("Unexpected length/cookie");
+          break;
+        }
+
+        assert(NKE_MAX_COOKIE_LENGTH == sizeof (inst->cookies[inst->num_cookies].cookie));
+        assert(NKE_MAX_COOKIES == sizeof (inst->cookies) /
+                                  sizeof (inst->cookies[inst->num_cookies]));
+        inst->cookies[inst->num_cookies].length = length;
+        memcpy(inst->cookies[inst->num_cookies].cookie, data, length);
+
+        inst->num_cookies++;
+        break;
+      case NKE_RECORD_NTPV4_SERVER_NEGOTIATION:
+        if (length < 1 || length >= sizeof (inst->server_name)) {
+          DEBUG_LOG("Invalid server name");
+          error = 1;
+          break;
+        }
+
+        memcpy(inst->server_name, data, length);
+        inst->server_name[length] = '\0';
+
+        /* Make sure the name is printable and has no spaces */
+        for (i = 0; i < length && isgraph((unsigned char)inst->server_name[i]); i++)
+          ;
+        if (i != length) {
+          DEBUG_LOG("Invalid server name");
+          error = 1;
+          break;
+        }
+
+        DEBUG_LOG("Negotiated server %s", inst->server_name);
+        break;
+      case NKE_RECORD_NTPV4_PORT_NEGOTIATION:
+        if (length != 2) {
+          DEBUG_LOG("Invalid port");
+          error = 1;
+          break;
+        }
+        inst->ntp_address.port = ntohs(data[0]);
+        DEBUG_LOG("Negotiated port %d", inst->ntp_address.port);
+        break;
+      default:
+        DEBUG_LOG("Unknown record type=%d length=%d critical=%d", type, length, critical);
+        if (critical)
+          error = 1;
+    }
+  }
+
+  DEBUG_LOG("NTS-KE response: error=%d next=%d aead=%d",
+            error, next_protocol, aead_algorithm);
+
+  if (error || inst->num_cookies == 0 ||
+      next_protocol != NKE_NEXT_PROTOCOL_NTPV4 ||
+      aead_algorithm != AEAD_AES_SIV_CMAC_256)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+handle_message(void *arg)
+{
+  NKC_Instance inst = arg;
+
+  if (!process_response(inst)) {
+    LOG(LOGS_ERR, "Received invalid NTS-KE response from %s", inst->name);
+    return 0;
+  }
+
+  if (!NKSN_GetKeys(inst->session, inst->context.algorithm,
+                    &inst->context.c2s, &inst->context.s2c))
+    return 0;
+
+  if (inst->server_name[0] != '\0') {
+    if (inst->resolving_name)
+      return 0;
+    if (!UTI_StringToIP(inst->server_name, &inst->ntp_address.ip_addr)) {
+      int length = strlen(inst->server_name);
+
+      /* Add a trailing dot if not present to force the name to be
+         resolved as a fully qualified domain name */
+      if (length < 1 || length + 1 >= sizeof (inst->server_name))
+        return 0;
+      if (inst->server_name[length - 1] != '.') {
+        inst->server_name[length] = '.';
+        inst->server_name[length + 1] = '\0';
+      }
+
+      DNS_Name2IPAddressAsync(inst->server_name, name_resolve_handler, inst);
+      inst->resolving_name = 1;
+    }
+  }
+
+  inst->got_response = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+NKC_Instance
+NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set)
+{
+  const char **trusted_certs;
+  uint32_t *certs_ids;
+  NKC_Instance inst;
+  int n_certs;
+
+  inst = MallocNew(struct NKC_Instance_Record);
+
+  inst->address = *address;
+  inst->name = Strdup(name);
+  inst->session = NKSN_CreateInstance(0, inst->name, handle_message, inst);
+  inst->resolving_name = 0;
+  inst->destroying = 0;
+  inst->got_response = 0;
+
+  n_certs = CNF_GetNtsTrustedCertsPaths(&trusted_certs, &certs_ids);
+
+  /* Share the credentials among clients using the default set of trusted
+     certificates, which likely contains most certificates */
+  if (cert_set == 0) {
+    if (!default_credentials)
+      default_credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                             n_certs, cert_set);
+    inst->credentials = default_credentials;
+    if (default_credentials)
+      default_credentials_refs++;
+  } else {
+    inst->credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                         n_certs, cert_set);
+  }
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NKC_DestroyInstance(NKC_Instance inst)
+{
+  NKSN_DestroyInstance(inst->session);
+
+  Free(inst->name);
+
+  if (inst->credentials) {
+    if (inst->credentials == default_credentials) {
+      default_credentials_refs--;
+      if (default_credentials_refs <= 0) {
+        NKSN_DestroyCertCredentials(default_credentials);
+        default_credentials = NULL;
+      }
+    } else {
+      NKSN_DestroyCertCredentials(inst->credentials);
+    }
+  }
+
+  /* If the asynchronous resolver is running, let the handler free
+     the instance later */
+  if (inst->resolving_name) {
+    inst->destroying = 1;
+    return;
+  }
+
+  Free(inst);
+}
+
+/* ================================================== */
+
+int
+NKC_Start(NKC_Instance inst)
+{
+  IPSockAddr local_addr;
+  char label[512], *iface;
+  int sock_fd;
+
+  assert(!NKC_IsActive(inst));
+
+  inst->got_response = 0;
+
+  if (!inst->credentials) {
+    DEBUG_LOG("Missing client credentials");
+    return 0;
+  }
+
+  /* Follow the bindacqaddress and bindacqdevice settings */
+  CNF_GetBindAcquisitionAddress(inst->address.ip_addr.family, &local_addr.ip_addr);
+  local_addr.port = 0;
+  iface = CNF_GetBindAcquisitionInterface();
+
+  /* Make a label containing both the address and name of the server */
+  if (snprintf(label, sizeof (label), "%s (%s)",
+               UTI_IPSockAddrToString(&inst->address), inst->name) >= sizeof (label))
+    ;
+
+  sock_fd = SCK_OpenTcpSocket(&inst->address, &local_addr, iface, 0);
+  if (sock_fd < 0) {
+    LOG(LOGS_ERR, "Could not connect to %s", label);
+    return 0;
+  }
+
+  /* Start an NTS-KE session */
+  if (!NKSN_StartSession(inst->session, sock_fd, label, inst->credentials, CLIENT_TIMEOUT)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  /* Send a request */
+  if (!prepare_request(inst)) {
+    DEBUG_LOG("Could not prepare NTS-KE request");
+    NKSN_StopSession(inst->session);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKC_IsActive(NKC_Instance inst)
+{
+  return !NKSN_IsStopped(inst->session) || inst->resolving_name;
+}
+
+/* ================================================== */
+
+int
+NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
+               NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+               IPSockAddr *ntp_address)
+{
+  int i;
+
+  if (!inst->got_response || inst->resolving_name)
+    return 0;
+
+  *context = inst->context;
+
+  for (i = 0; i < inst->num_cookies && i < max_cookies; i++)
+    cookies[i] = inst->cookies[i];
+  *num_cookies = i;
+
+  *ntp_address = inst->ntp_address;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKC_GetRetryFactor(NKC_Instance inst)
+{
+  return NKSN_GetRetryFactor(inst->session);
+}
diff --git a/nts_ke_client.h b/nts_ke_client.h
new file mode 100644
index 0000000..a1bedb6
--- /dev/null
+++ b/nts_ke_client.h
@@ -0,0 +1,56 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE client
+  */
+
+#ifndef GOT_NTS_KE_CLIENT_H
+#define GOT_NTS_KE_CLIENT_H
+
+#include "addressing.h"
+#include "nts_ke.h"
+
+typedef struct NKC_Instance_Record *NKC_Instance;
+
+/* Create a client NTS-KE instance */
+extern NKC_Instance NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set);
+
+/* Destroy an instance */
+extern void NKC_DestroyInstance(NKC_Instance inst);
+
+/* Connect to the server, start an NTS-KE session, send an NTS-KE request, and
+   process the response (asynchronously) */
+extern int NKC_Start(NKC_Instance inst);
+
+/* Check if the client is still running */
+extern int NKC_IsActive(NKC_Instance inst);
+
+/* Get the NTS data if the session was successful */
+extern int NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
+                          NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+                          IPSockAddr *ntp_address);
+
+/* Get a factor to calculate retry interval (in log2 seconds) */
+extern int NKC_GetRetryFactor(NKC_Instance inst);
+
+#endif
diff --git a/nts_ke_server.c b/nts_ke_server.c
new file mode 100644
index 0000000..ece1b4c
--- /dev/null
+++ b/nts_ke_server.c
@@ -0,0 +1,967 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE server
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_server.h"
+
+#include "array.h"
+#include "conf.h"
+#include "clientlog.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp_core.h"
+#include "nts_ke_session.h"
+#include "privops.h"
+#include "siv.h"
+#include "socket.h"
+#include "sched.h"
+#include "sys.h"
+#include "util.h"
+
+#define SERVER_TIMEOUT 2.0
+
+#define SERVER_COOKIE_SIV AEAD_AES_SIV_CMAC_256
+#define SERVER_COOKIE_NONCE_LENGTH 16
+
+#define KEY_ID_INDEX_BITS 2
+#define MAX_SERVER_KEYS (1U << KEY_ID_INDEX_BITS)
+#define FUTURE_KEYS 1
+
+#define DUMP_FILENAME "ntskeys"
+#define DUMP_IDENTIFIER "NKS0\n"
+
+#define INVALID_SOCK_FD (-7)
+
+typedef struct {
+  uint32_t key_id;
+  unsigned char nonce[SERVER_COOKIE_NONCE_LENGTH];
+} ServerCookieHeader;
+
+typedef struct {
+  uint32_t id;
+  unsigned char key[SIV_MAX_KEY_LENGTH];
+  SIV_Instance siv;
+} ServerKey;
+
+typedef struct {
+  uint32_t key_id;
+  unsigned char key[SIV_MAX_KEY_LENGTH];
+  IPAddr client_addr;
+  uint16_t client_port;
+  uint16_t _pad;
+} HelperRequest;
+
+/* ================================================== */
+
+static ServerKey server_keys[MAX_SERVER_KEYS];
+static int current_server_key;
+static double last_server_key_ts;
+static int key_rotation_interval;
+
+static int server_sock_fd4;
+static int server_sock_fd6;
+
+static int helper_sock_fd;
+static int is_helper;
+
+static int initialised = 0;
+
+/* Array of NKSN instances */
+static ARR_Instance sessions;
+static NKSN_Credentials server_credentials;
+
+/* ================================================== */
+
+static int handle_message(void *arg);
+
+/* ================================================== */
+
+static int
+handle_client(int sock_fd, IPSockAddr *addr)
+{
+  NKSN_Instance inst, *instp;
+  int i;
+
+  /* Leave at least half of the descriptors which can handled by select()
+     to other use */
+  if (sock_fd > FD_SETSIZE / 2) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(addr), "too many descriptors");
+    return 0;
+  }
+
+  /* Find an unused server slot or one with an already stopped session */
+  for (i = 0, inst = NULL; i < ARR_GetSize(sessions); i++) {
+    instp = ARR_GetElement(sessions, i);
+    if (!*instp) {
+      /* NULL handler arg will be replaced with the session instance */
+      inst = NKSN_CreateInstance(1, NULL, handle_message, NULL);
+      *instp = inst;
+      break;
+    } else if (NKSN_IsStopped(*instp)) {
+      inst = *instp;
+      break;
+    }
+  }
+
+  if (!inst) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(addr), "too many connections");
+    return 0;
+  }
+
+  assert(server_credentials);
+
+  if (!NKSN_StartSession(inst, sock_fd, UTI_IPSockAddrToString(addr),
+                         server_credentials, SERVER_TIMEOUT))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+handle_helper_request(int fd, int event, void *arg)
+{
+  SCK_Message *message;
+  HelperRequest *req;
+  IPSockAddr client_addr;
+  int sock_fd;
+
+  /* Receive the helper request with the NTS-KE session socket.
+     With multiple helpers EAGAIN errors are expected here. */
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message)
+    return;
+
+  sock_fd = message->descriptor;
+  if (sock_fd < 0) {
+    /* Message with no descriptor is a shutdown command */
+    SCH_QuitProgram();
+    return;
+  }
+
+  if (!initialised) {
+    DEBUG_LOG("Uninitialised helper");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  if (message->length != sizeof (HelperRequest))
+    LOG_FATAL("Invalid helper request");
+
+  req = message->data;
+
+  /* Extract the current server key and client address from the request */
+  server_keys[current_server_key].id = ntohl(req->key_id);
+  assert(sizeof (server_keys[current_server_key].key) == sizeof (req->key));
+  memcpy(server_keys[current_server_key].key, req->key,
+         sizeof (server_keys[current_server_key].key));
+  UTI_IPNetworkToHost(&req->client_addr, &client_addr.ip_addr);
+  client_addr.port = ntohs(req->client_port);
+
+  if (!SIV_SetKey(server_keys[current_server_key].siv, server_keys[current_server_key].key,
+                  SIV_GetKeyLength(SERVER_COOKIE_SIV)))
+    LOG_FATAL("Could not set SIV key");
+
+  if (!handle_client(sock_fd, &client_addr)) {
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  DEBUG_LOG("Accepted helper request fd=%d", sock_fd);
+}
+
+/* ================================================== */
+
+static void
+accept_connection(int listening_fd, int event, void *arg)
+{
+  SCK_Message message;
+  IPSockAddr addr;
+  int log_index, sock_fd;
+  struct timespec now;
+
+  sock_fd = SCK_AcceptConnection(listening_fd, &addr);
+  if (sock_fd < 0)
+    return;
+
+  if (!NCR_CheckAccessRestriction(&addr.ip_addr)) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(&addr), "access denied");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  log_index = CLG_LogServiceAccess(CLG_NTSKE, &addr.ip_addr, &now);
+  if (log_index >= 0 && CLG_LimitServiceRate(CLG_NTSKE, log_index)) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(&addr), "rate limit");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  /* Pass the socket to a helper process if enabled.  Otherwise, handle the
+     client in the main process. */
+  if (helper_sock_fd != INVALID_SOCK_FD) {
+    HelperRequest req;
+
+    memset(&req, 0, sizeof (req));
+
+    /* Include the current server key and client address in the request */
+    req.key_id = htonl(server_keys[current_server_key].id);
+    assert(sizeof (req.key) == sizeof (server_keys[current_server_key].key));
+    memcpy(req.key, server_keys[current_server_key].key, sizeof (req.key));
+    UTI_IPHostToNetwork(&addr.ip_addr, &req.client_addr);
+    req.client_port = htons(addr.port);
+
+    SCK_InitMessage(&message, SCK_ADDR_UNSPEC);
+    message.data = &req;
+    message.length = sizeof (req);
+    message.descriptor = sock_fd;
+
+    errno = 0;
+    if (!SCK_SendMessage(helper_sock_fd, &message, SCK_FLAG_MSG_DESCRIPTOR)) {
+      /* If sending failed with EPIPE, it means all helpers closed their end of
+         the socket (e.g. due to a fatal error) */
+      if (errno == EPIPE)
+        LOG_FATAL("NTS-KE helpers failed");
+      SCK_CloseSocket(sock_fd);
+      return;
+    }
+
+    SCK_CloseSocket(sock_fd);
+  } else {
+    if (!handle_client(sock_fd, &addr)) {
+      SCK_CloseSocket(sock_fd);
+      return;
+    }
+  }
+
+  DEBUG_LOG("Accepted connection from %s fd=%d", UTI_IPSockAddrToString(&addr), sock_fd);
+}
+
+/* ================================================== */
+
+static int
+open_socket(int family)
+{
+  IPSockAddr local_addr;
+  int backlog, sock_fd;
+  char *iface;
+
+  if (!SCK_IsIpFamilyEnabled(family))
+    return INVALID_SOCK_FD;
+
+  CNF_GetBindAddress(family, &local_addr.ip_addr);
+  local_addr.port = CNF_GetNtsServerPort();
+  iface = CNF_GetBindNtpInterface();
+
+  sock_fd = SCK_OpenTcpSocket(NULL, &local_addr, iface, 0);
+  if (sock_fd < 0) {
+    LOG(LOGS_ERR, "Could not open NTS-KE socket on %s", UTI_IPSockAddrToString(&local_addr));
+    return INVALID_SOCK_FD;
+  }
+
+  /* Set the maximum number of waiting connections on the socket to the maximum
+     number of concurrent sessions */
+  backlog = MAX(CNF_GetNtsServerProcesses(), 1) * CNF_GetNtsServerConnections();
+
+  if (!SCK_ListenOnSocket(sock_fd, backlog)) {
+    SCK_CloseSocket(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, accept_connection, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static void
+helper_signal(int x)
+{
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static int
+prepare_response(NKSN_Instance session, int error, int next_protocol, int aead_algorithm)
+{
+  NKE_Context context;
+  NKE_Cookie cookie;
+  char *ntp_server;
+  uint16_t datum;
+  int i;
+
+  DEBUG_LOG("NTS KE response: error=%d next=%d aead=%d", error, next_protocol, aead_algorithm);
+
+  NKSN_BeginMessage(session);
+
+  if (error >= 0) {
+    datum = htons(error);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_ERROR, &datum, sizeof (datum)))
+      return 0;
+  } else if (next_protocol < 0) {
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, NULL, 0))
+      return 0;
+  } else if (aead_algorithm < 0) {
+    datum = htons(next_protocol);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+      return 0;
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, NULL, 0))
+      return 0;
+  } else {
+    datum = htons(next_protocol);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+      return 0;
+
+    datum = htons(aead_algorithm);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, &datum, sizeof (datum)))
+      return 0;
+
+    if (CNF_GetNTPPort() != NTP_PORT) {
+      datum = htons(CNF_GetNTPPort());
+      if (!NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_PORT_NEGOTIATION, &datum, sizeof (datum)))
+        return 0;
+    }
+
+    ntp_server = CNF_GetNtsNtpServer();
+    if (ntp_server) {
+      if (!NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                          ntp_server, strlen(ntp_server)))
+        return 0;
+    }
+
+    context.algorithm = aead_algorithm;
+
+    if (!NKSN_GetKeys(session, aead_algorithm, &context.c2s, &context.s2c))
+      return 0;
+
+    for (i = 0; i < NKE_MAX_COOKIES; i++) {
+      if (!NKS_GenerateCookie(&context, &cookie))
+        return 0;
+      if (!NKSN_AddRecord(session, 0, NKE_RECORD_COOKIE, cookie.cookie, cookie.length))
+        return 0;
+    }
+  }
+
+  if (!NKSN_EndMessage(session))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_request(NKSN_Instance session)
+{
+  int next_protocol_records = 0, aead_algorithm_records = 0;
+  int next_protocol_values = 0, aead_algorithm_values = 0;
+  int next_protocol = -1, aead_algorithm = -1, error = -1;
+  int i, critical, type, length;
+  uint16_t data[NKE_MAX_RECORD_BODY_LENGTH / sizeof (uint16_t)];
+
+  assert(NKE_MAX_RECORD_BODY_LENGTH % sizeof (uint16_t) == 0);
+  assert(sizeof (uint16_t) == 2);
+
+  while (error < 0) {
+    if (!NKSN_GetRecord(session, &critical, &type, &length, &data, sizeof (data)))
+      break;
+
+    switch (type) {
+      case NKE_RECORD_NEXT_PROTOCOL:
+        if (!critical || length < 2 || length % 2 != 0) {
+          error = NKE_ERROR_BAD_REQUEST;
+          break;
+        }
+
+        next_protocol_records++;
+
+        for (i = 0; i < MIN(length, sizeof (data)) / 2; i++) {
+          next_protocol_values++;
+          if (ntohs(data[i]) == NKE_NEXT_PROTOCOL_NTPV4)
+            next_protocol = NKE_NEXT_PROTOCOL_NTPV4;
+        }
+        break;
+      case NKE_RECORD_AEAD_ALGORITHM:
+        if (length < 2 || length % 2 != 0) {
+          error = NKE_ERROR_BAD_REQUEST;
+          break;
+        }
+
+        aead_algorithm_records++;
+
+        for (i = 0; i < MIN(length, sizeof (data)) / 2; i++) {
+          aead_algorithm_values++;
+          if (ntohs(data[i]) == AEAD_AES_SIV_CMAC_256)
+            aead_algorithm = AEAD_AES_SIV_CMAC_256;
+        }
+        break;
+      case NKE_RECORD_ERROR:
+      case NKE_RECORD_WARNING:
+      case NKE_RECORD_COOKIE:
+        error = NKE_ERROR_BAD_REQUEST;
+        break;
+      default:
+        if (critical)
+          error = NKE_ERROR_UNRECOGNIZED_CRITICAL_RECORD;
+    }
+  }
+
+  if (error < 0) {
+    if (next_protocol_records != 1 || next_protocol_values < 1 ||
+        (next_protocol == NKE_NEXT_PROTOCOL_NTPV4 &&
+         (aead_algorithm_records != 1 || aead_algorithm_values < 1)))
+      error = NKE_ERROR_BAD_REQUEST;
+  }
+
+  if (!prepare_response(session, error, next_protocol, aead_algorithm))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+handle_message(void *arg)
+{
+  NKSN_Instance session = arg;
+
+  return process_request(session);
+}
+
+/* ================================================== */
+
+static void
+generate_key(int index)
+{
+  int key_length;
+
+  if (index < 0 || index >= MAX_SERVER_KEYS)
+    assert(0);
+
+  key_length = SIV_GetKeyLength(SERVER_COOKIE_SIV);
+  if (key_length > sizeof (server_keys[index].key))
+    assert(0);
+
+  UTI_GetRandomBytesUrandom(server_keys[index].key, key_length);
+
+  if (!server_keys[index].siv ||
+      !SIV_SetKey(server_keys[index].siv, server_keys[index].key, key_length))
+    LOG_FATAL("Could not set SIV key");
+
+  UTI_GetRandomBytes(&server_keys[index].id, sizeof (server_keys[index].id));
+
+  /* Encode the index in the lowest bits of the ID */
+  server_keys[index].id &= -1U << KEY_ID_INDEX_BITS;
+  server_keys[index].id |= index;
+
+  DEBUG_LOG("Generated server key %"PRIX32, server_keys[index].id);
+
+  last_server_key_ts = SCH_GetLastEventMonoTime();
+}
+
+/* ================================================== */
+
+static void
+save_keys(void)
+{
+  char buf[SIV_MAX_KEY_LENGTH * 2 + 1], *dump_dir;
+  int i, index, key_length;
+  double last_key_age;
+  FILE *f;
+
+  /* Don't save the keys if rotation is disabled to enable an external
+     management of the keys (e.g. share them with another server) */
+  if (key_rotation_interval == 0)
+    return;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  f = UTI_OpenFile(dump_dir, DUMP_FILENAME, ".tmp", 'w', 0600);
+  if (!f)
+    return;
+
+  key_length = SIV_GetKeyLength(SERVER_COOKIE_SIV);
+  last_key_age = SCH_GetLastEventMonoTime() - last_server_key_ts;
+
+  if (fprintf(f, "%s%d %.1f\n", DUMP_IDENTIFIER, SERVER_COOKIE_SIV, last_key_age) < 0)
+    goto error;
+
+  for (i = 0; i < MAX_SERVER_KEYS; i++) {
+    index = (current_server_key + i + 1 + FUTURE_KEYS) % MAX_SERVER_KEYS;
+
+    if (key_length > sizeof (server_keys[index].key) ||
+        !UTI_BytesToHex(server_keys[index].key, key_length, buf, sizeof (buf)) ||
+        fprintf(f, "%08"PRIX32" %s\n", server_keys[index].id, buf) < 0)
+      goto error;
+  }
+
+  fclose(f);
+
+  /* Rename the temporary file, or remove it if that fails */
+  if (!UTI_RenameTempFile(dump_dir, DUMP_FILENAME, ".tmp", NULL)) {
+    if (!UTI_RemoveFile(dump_dir, DUMP_FILENAME, ".tmp"))
+      ;
+  }
+
+  return;
+
+error:
+  DEBUG_LOG("Could not %s server keys", "save");
+  fclose(f);
+
+  if (!UTI_RemoveFile(dump_dir, DUMP_FILENAME, NULL))
+    ;
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 2
+
+static int
+load_keys(void)
+{
+  char *dump_dir, line[1024], *words[MAX_WORDS];
+  unsigned char key[SIV_MAX_KEY_LENGTH];
+  int i, index, key_length, algorithm;
+  double key_age;
+  FILE *f;
+  uint32_t id;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return 0;
+
+  f = UTI_OpenFile(dump_dir, DUMP_FILENAME, NULL, 'r', 0);
+  if (!f)
+    return 0;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 2 ||
+        sscanf(words[0], "%d", &algorithm) != 1 || algorithm != SERVER_COOKIE_SIV ||
+        sscanf(words[1], "%lf", &key_age) != 1)
+    goto error;
+
+  key_length = SIV_GetKeyLength(SERVER_COOKIE_SIV);
+  last_server_key_ts = SCH_GetLastEventMonoTime() - MAX(key_age, 0.0);
+
+  for (i = 0; i < MAX_SERVER_KEYS && fgets(line, sizeof (line), f); i++) {
+    if (UTI_SplitString(line, words, MAX_WORDS) != 2 ||
+        sscanf(words[0], "%"PRIX32, &id) != 1)
+      goto error;
+
+    if (UTI_HexToBytes(words[1], key, sizeof (key)) != key_length)
+      goto error;
+
+    index = id % MAX_SERVER_KEYS;
+
+    server_keys[index].id = id;
+    assert(sizeof (server_keys[index].key) == sizeof (key));
+    memcpy(server_keys[index].key, key, key_length);
+
+    if (!SIV_SetKey(server_keys[index].siv, server_keys[index].key, key_length))
+      LOG_FATAL("Could not set SIV key");
+
+    DEBUG_LOG("Loaded key %"PRIX32, id);
+
+    current_server_key = (index + MAX_SERVER_KEYS - FUTURE_KEYS) % MAX_SERVER_KEYS;
+  }
+
+  fclose(f);
+
+  return 1;
+
+error:
+  DEBUG_LOG("Could not %s server keys", "load");
+  fclose(f);
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+key_timeout(void *arg)
+{
+  current_server_key = (current_server_key + 1) % MAX_SERVER_KEYS;
+  generate_key((current_server_key + FUTURE_KEYS) % MAX_SERVER_KEYS);
+  save_keys();
+
+  SCH_AddTimeoutByDelay(key_rotation_interval, key_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+run_helper(uid_t uid, gid_t gid, int scfilter_level)
+{
+  LOG_Severity log_severity;
+
+  /* Finish minimal initialisation and run using the scheduler loop
+     similarly to the main process */
+
+  DEBUG_LOG("Helper started");
+
+  /* Suppress a log message about disabled clock control */
+  log_severity = LOG_GetMinSeverity();
+  LOG_SetMinSeverity(LOGS_ERR);
+
+  SYS_Initialise(0);
+  LOG_SetMinSeverity(log_severity);
+
+  if (!geteuid() && (uid || gid))
+    SYS_DropRoot(uid, gid, SYS_NTSKE_HELPER);
+
+  NKS_Initialise();
+
+  UTI_SetQuitSignalsHandler(helper_signal, 1);
+  if (scfilter_level != 0)
+    SYS_EnableSystemCallFilter(scfilter_level, SYS_NTSKE_HELPER);
+
+  SCH_MainLoop();
+
+  DEBUG_LOG("Helper exiting");
+
+  NKS_Finalise();
+  SCK_Finalise();
+  SYS_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+  CNF_Finalise();
+  LOG_Finalise();
+
+  UTI_ResetGetRandomFunctions();
+
+  exit(0);
+}
+
+/* ================================================== */
+
+void
+NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level)
+{
+  int i, processes, sock_fd1, sock_fd2;
+  const char **certs, **keys;
+  char prefix[16];
+  pid_t pid;
+
+  helper_sock_fd = INVALID_SOCK_FD;
+  is_helper = 0;
+
+  if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0)
+    return;
+
+  processes = CNF_GetNtsServerProcesses();
+  if (processes <= 0)
+    return;
+
+  /* Start helper processes to perform (computationally expensive) NTS-KE
+     sessions with clients on sockets forwarded from the main process */
+
+  sock_fd1 = SCK_OpenUnixSocketPair(0, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");
+
+  for (i = 0; i < processes; i++) {
+    pid = fork();
+
+    if (pid < 0)
+      LOG_FATAL("fork() failed : %s", strerror(errno));
+
+    if (pid > 0)
+      continue;
+
+    is_helper = 1;
+
+    UTI_ResetGetRandomFunctions();
+
+    snprintf(prefix, sizeof (prefix), "nks#%d:", i + 1);
+    LOG_SetDebugPrefix(prefix);
+    LOG_CloseParentFd();
+
+    SCK_CloseSocket(sock_fd1);
+    SCH_AddFileHandler(sock_fd2, SCH_FILE_INPUT, handle_helper_request, NULL);
+
+    run_helper(uid, gid, scfilter_level);
+  }
+
+  SCK_CloseSocket(sock_fd2);
+  helper_sock_fd = sock_fd1;
+}
+
+/* ================================================== */
+
+void
+NKS_Initialise(void)
+{
+  const char **certs, **keys;
+  int i, n_certs_keys;
+  double key_delay;
+
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+
+  n_certs_keys = CNF_GetNtsServerCertAndKeyFiles(&certs, &keys);
+  if (n_certs_keys <= 0)
+    return;
+
+  if (helper_sock_fd == INVALID_SOCK_FD) {
+    server_credentials = NKSN_CreateServerCertCredentials(certs, keys, n_certs_keys);
+    if (!server_credentials)
+      return;
+  } else {
+    server_credentials = NULL;
+  }
+
+  sessions = ARR_CreateInstance(sizeof (NKSN_Instance));
+  for (i = 0; i < CNF_GetNtsServerConnections(); i++)
+    *(NKSN_Instance *)ARR_GetNewElement(sessions) = NULL;
+
+  /* Generate random keys, even if they will be replaced by reloaded keys,
+     or unused (in the helper) */
+  for (i = 0; i < MAX_SERVER_KEYS; i++) {
+    server_keys[i].siv = SIV_CreateInstance(SERVER_COOKIE_SIV);
+    generate_key(i);
+  }
+
+  current_server_key = MAX_SERVER_KEYS - 1;
+
+  if (!is_helper) {
+    server_sock_fd4 = open_socket(IPADDR_INET4);
+    server_sock_fd6 = open_socket(IPADDR_INET6);
+
+    key_rotation_interval = MAX(CNF_GetNtsRotate(), 0);
+
+    /* Reload saved keys, or save the new keys */
+    if (!load_keys())
+      save_keys();
+
+    if (key_rotation_interval > 0) {
+      key_delay = key_rotation_interval - (SCH_GetLastEventMonoTime() - last_server_key_ts);
+      SCH_AddTimeoutByDelay(MAX(key_delay, 0.0), key_timeout, NULL);
+    }
+  }
+
+  initialised = 1;
+}
+
+/* ================================================== */
+
+void
+NKS_Finalise(void)
+{
+  int i;
+
+  if (!initialised)
+    return;
+
+  if (helper_sock_fd != INVALID_SOCK_FD) {
+    /* Send the helpers a request to exit */
+    for (i = 0; i < CNF_GetNtsServerProcesses(); i++) {
+      if (!SCK_Send(helper_sock_fd, "", 1, 0))
+        ;
+    }
+    SCK_CloseSocket(helper_sock_fd);
+  }
+  if (server_sock_fd4 != INVALID_SOCK_FD)
+    SCK_CloseSocket(server_sock_fd4);
+  if (server_sock_fd6 != INVALID_SOCK_FD)
+    SCK_CloseSocket(server_sock_fd6);
+
+  if (!is_helper)
+    save_keys();
+
+  for (i = 0; i < MAX_SERVER_KEYS; i++)
+    SIV_DestroyInstance(server_keys[i].siv);
+
+  for (i = 0; i < ARR_GetSize(sessions); i++) {
+    NKSN_Instance session = *(NKSN_Instance *)ARR_GetElement(sessions, i);
+    if (session)
+      NKSN_DestroyInstance(session);
+  }
+  ARR_DestroyInstance(sessions);
+
+  if (server_credentials)
+    NKSN_DestroyCertCredentials(server_credentials);
+}
+
+/* ================================================== */
+
+void
+NKS_DumpKeys(void)
+{
+  save_keys();
+}
+
+/* ================================================== */
+
+void
+NKS_ReloadKeys(void)
+{
+  /* Don't load the keys if they are expected to be generated by this server
+     instance (i.e. they are already loaded) to not delay the next rotation */
+  if (key_rotation_interval > 0)
+    return;
+
+  load_keys();
+}
+
+/* ================================================== */
+
+/* A server cookie consists of key ID, nonce, and encrypted C2S+S2C keys */
+
+int
+NKS_GenerateCookie(NKE_Context *context, NKE_Cookie *cookie)
+{
+  unsigned char plaintext[2 * NKE_MAX_KEY_LENGTH], *ciphertext;
+  int plaintext_length, tag_length;
+  ServerCookieHeader *header;
+  ServerKey *key;
+
+  if (!initialised) {
+    DEBUG_LOG("NTS server disabled");
+    return 0;
+  }
+
+  /* The algorithm is hardcoded for now */
+  if (context->algorithm != AEAD_AES_SIV_CMAC_256) {
+    DEBUG_LOG("Unexpected SIV algorithm");
+    return 0;
+  }
+
+  if (context->c2s.length < 0 || context->c2s.length > NKE_MAX_KEY_LENGTH ||
+      context->s2c.length < 0 || context->s2c.length > NKE_MAX_KEY_LENGTH) {
+    DEBUG_LOG("Invalid key length");
+    return 0;
+  }
+
+  key = &server_keys[current_server_key];
+
+  header = (ServerCookieHeader *)cookie->cookie;
+
+  header->key_id = htonl(key->id);
+  UTI_GetRandomBytes(header->nonce, sizeof (header->nonce));
+
+  plaintext_length = context->c2s.length + context->s2c.length;
+  assert(plaintext_length <= sizeof (plaintext));
+  memcpy(plaintext, context->c2s.key, context->c2s.length);
+  memcpy(plaintext + context->c2s.length, context->s2c.key, context->s2c.length);
+
+  tag_length = SIV_GetTagLength(key->siv);
+  cookie->length = sizeof (*header) + plaintext_length + tag_length;
+  assert(cookie->length <= sizeof (cookie->cookie));
+  ciphertext = cookie->cookie + sizeof (*header);
+
+  if (!SIV_Encrypt(key->siv, header->nonce, sizeof (header->nonce),
+                   "", 0,
+                   plaintext, plaintext_length,
+                   ciphertext, plaintext_length + tag_length)) {
+    DEBUG_LOG("Could not encrypt cookie");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Context *context)
+{
+  unsigned char plaintext[2 * NKE_MAX_KEY_LENGTH], *ciphertext;
+  int ciphertext_length, plaintext_length, tag_length;
+  ServerCookieHeader *header;
+  ServerKey *key;
+  uint32_t key_id;
+
+  if (!initialised) {
+    DEBUG_LOG("NTS server disabled");
+    return 0;
+  }
+
+  if (cookie->length <= (int)sizeof (*header)) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  header = (ServerCookieHeader *)cookie->cookie;
+  ciphertext = cookie->cookie + sizeof (*header);
+  ciphertext_length = cookie->length - sizeof (*header);
+
+  key_id = ntohl(header->key_id);
+  key = &server_keys[key_id % MAX_SERVER_KEYS];
+  if (key_id != key->id) {
+    DEBUG_LOG("Unknown key %"PRIX32, key_id);
+    return 0;
+  }
+
+  tag_length = SIV_GetTagLength(key->siv);
+  if (tag_length >= ciphertext_length) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  plaintext_length = ciphertext_length - tag_length;
+  if (plaintext_length > sizeof (plaintext) || plaintext_length % 2 != 0) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  if (!SIV_Decrypt(key->siv, header->nonce, sizeof (header->nonce),
+                   "", 0,
+                   ciphertext, ciphertext_length,
+                   plaintext, plaintext_length)) {
+    DEBUG_LOG("Could not decrypt cookie");
+    return 0;
+  }
+
+  context->algorithm = AEAD_AES_SIV_CMAC_256;
+
+  context->c2s.length = plaintext_length / 2;
+  context->s2c.length = plaintext_length / 2;
+  assert(context->c2s.length <= sizeof (context->c2s.key));
+
+  memcpy(context->c2s.key, plaintext, context->c2s.length);
+  memcpy(context->s2c.key, plaintext + context->c2s.length, context->s2c.length);
+
+  return 1;
+}
diff --git a/nts_ke_server.h b/nts_ke_server.h
new file mode 100644
index 0000000..4d8a92a
--- /dev/null
+++ b/nts_ke_server.h
@@ -0,0 +1,49 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE server
+  */
+
+#ifndef GOT_NTS_KE_SERVER_H
+#define GOT_NTS_KE_SERVER_H
+
+#include "nts_ke.h"
+
+/* Init and fini functions */
+extern void NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level);
+extern void NKS_Initialise(void);
+extern void NKS_Finalise(void);
+
+/* Save the current server keys */
+extern void NKS_DumpKeys(void);
+
+/* Reload the keys */
+extern void NKS_ReloadKeys(void);
+
+/* Generate an NTS cookie with a given context */
+extern int NKS_GenerateCookie(NKE_Context *context, NKE_Cookie *cookie);
+
+/* Validate a cookie and decode the context */
+extern int NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Context *context);
+
+#endif
diff --git a/nts_ke_session.c b/nts_ke_session.c
new file mode 100644
index 0000000..dfcd18a
--- /dev/null
+++ b/nts_ke_session.c
@@ -0,0 +1,927 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE session used by server and client
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_session.h"
+
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "siv.h"
+#include "socket.h"
+#include "sched.h"
+#include "util.h"
+
+#include <gnutls/gnutls.h>
+#include <gnutls/x509.h>
+
+#define INVALID_SOCK_FD (-8)
+
+struct RecordHeader {
+  uint16_t type;
+  uint16_t body_length;
+};
+
+struct Message {
+  int length;
+  int sent;
+  int parsed;
+  int complete;
+  unsigned char data[NKE_MAX_MESSAGE_LENGTH];
+};
+
+typedef enum {
+  KE_WAIT_CONNECT,
+  KE_HANDSHAKE,
+  KE_SEND,
+  KE_RECEIVE,
+  KE_SHUTDOWN,
+  KE_STOPPED,
+} KeState;
+
+struct NKSN_Instance_Record {
+  int server;
+  char *server_name;
+  NKSN_MessageHandler handler;
+  void *handler_arg;
+
+  KeState state;
+  int sock_fd;
+  char *label;
+  gnutls_session_t tls_session;
+  SCH_TimeoutID timeout_id;
+  int retry_factor;
+
+  struct Message message;
+  int new_message;
+};
+
+/* ================================================== */
+
+static gnutls_priority_t priority_cache;
+
+static int credentials_counter = 0;
+
+static int clock_updates = 0;
+
+/* ================================================== */
+
+static void
+reset_message(struct Message *message)
+{
+  message->length = 0;
+  message->sent = 0;
+  message->parsed = 0;
+  message->complete = 0;
+}
+
+/* ================================================== */
+
+static int
+add_record(struct Message *message, int critical, int type, const void *body, int body_length)
+{
+  struct RecordHeader header;
+
+  assert(message->length <= sizeof (message->data));
+
+  if (body_length < 0 || body_length > 0xffff || type < 0 || type > 0x7fff ||
+      message->length + sizeof (header) + body_length > sizeof (message->data))
+    return 0;
+
+  header.type = htons(!!critical * NKE_RECORD_CRITICAL_BIT | type);
+  header.body_length = htons(body_length);
+
+  memcpy(&message->data[message->length], &header, sizeof (header));
+  message->length += sizeof (header);
+
+  if (body_length > 0) {
+    memcpy(&message->data[message->length], body, body_length);
+    message->length += body_length;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+reset_message_parsing(struct Message *message)
+{
+  message->parsed = 0;
+}
+
+/* ================================================== */
+
+static int
+get_record(struct Message *message, int *critical, int *type, int *body_length,
+           void *body, int buffer_length)
+{
+  struct RecordHeader header;
+  int blen, rlen;
+
+  if (message->length < message->parsed + sizeof (header) ||
+      buffer_length < 0)
+    return 0;
+
+  memcpy(&header, &message->data[message->parsed], sizeof (header));
+
+  blen = ntohs(header.body_length);
+  rlen = sizeof (header) + blen;
+  assert(blen >= 0 && rlen > 0);
+
+  if (message->length < message->parsed + rlen)
+    return 0;
+
+  if (critical)
+    *critical = !!(ntohs(header.type) & NKE_RECORD_CRITICAL_BIT);
+  if (type)
+    *type = ntohs(header.type) & ~NKE_RECORD_CRITICAL_BIT;
+  if (body)
+    memcpy(body, &message->data[message->parsed + sizeof (header)], MIN(buffer_length, blen));
+  if (body_length)
+    *body_length = blen;
+
+  message->parsed += rlen;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+check_message_format(struct Message *message, int eof)
+{
+  int critical = 0, type = -1, length = -1, ends = 0;
+
+  reset_message_parsing(message);
+  message->complete = 0;
+
+  while (get_record(message, &critical, &type, &length, NULL, 0)) {
+    if (type == NKE_RECORD_END_OF_MESSAGE) {
+      if (!critical || length != 0 || ends > 0)
+        return 0;
+      ends++;
+    }
+  }
+
+  /* If the message cannot be fully parsed, but more data may be coming,
+     consider the format to be ok */
+  if (message->length == 0 || message->parsed < message->length)
+    return !eof;
+
+  if (type != NKE_RECORD_END_OF_MESSAGE)
+    return !eof;
+
+  message->complete = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static gnutls_session_t
+create_tls_session(int server_mode, int sock_fd, const char *server_name,
+                   gnutls_certificate_credentials_t credentials,
+                   gnutls_priority_t priority)
+{
+  unsigned char alpn_name[sizeof (NKE_ALPN_NAME)];
+  gnutls_session_t session;
+  gnutls_datum_t alpn;
+  unsigned int flags;
+  int r;
+
+  r = gnutls_init(&session, GNUTLS_NONBLOCK | GNUTLS_NO_TICKETS |
+                  (server_mode ? GNUTLS_SERVER : GNUTLS_CLIENT));
+  if (r < 0) {
+    LOG(LOGS_ERR, "Could not %s TLS session : %s", "create", gnutls_strerror(r));
+    return NULL;
+  }
+
+  if (!server_mode) {
+    assert(server_name);
+
+    if (!UTI_IsStringIP(server_name)) {
+      r = gnutls_server_name_set(session, GNUTLS_NAME_DNS, server_name, strlen(server_name));
+      if (r < 0)
+        goto error;
+    }
+
+    flags = 0;
+
+    if (clock_updates < CNF_GetNoCertTimeCheck()) {
+      flags |= GNUTLS_VERIFY_DISABLE_TIME_CHECKS | GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS;
+      DEBUG_LOG("Disabled time checks");
+    }
+
+    gnutls_session_set_verify_cert(session, server_name, flags);
+  }
+
+  r = gnutls_priority_set(session, priority);
+  if (r < 0)
+    goto error;
+
+  r = gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, credentials);
+  if (r < 0)
+    goto error;
+
+  memcpy(alpn_name, NKE_ALPN_NAME, sizeof (alpn_name));
+  alpn.data = alpn_name;
+  alpn.size = sizeof (alpn_name) - 1;
+
+  r = gnutls_alpn_set_protocols(session, &alpn, 1, 0);
+  if (r < 0)
+    goto error;
+
+  gnutls_transport_set_int(session, sock_fd);
+
+  return session;
+
+error:
+  LOG(LOGS_ERR, "Could not %s TLS session : %s", "set", gnutls_strerror(r));
+  gnutls_deinit(session);
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+stop_session(NKSN_Instance inst)
+{
+  if (inst->state == KE_STOPPED)
+    return;
+
+  inst->state = KE_STOPPED;
+
+  SCH_RemoveFileHandler(inst->sock_fd);
+  SCK_CloseSocket(inst->sock_fd);
+  inst->sock_fd = INVALID_SOCK_FD;
+
+  Free(inst->label);
+  inst->label = NULL;
+
+  gnutls_deinit(inst->tls_session);
+  inst->tls_session = NULL;
+
+  SCH_RemoveTimeout(inst->timeout_id);
+  inst->timeout_id = 0;
+}
+
+/* ================================================== */
+
+static void
+session_timeout(void *arg)
+{
+  NKSN_Instance inst = arg;
+
+  LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE session with %s timed out", inst->label);
+
+  inst->timeout_id = 0;
+  stop_session(inst);
+}
+
+/* ================================================== */
+
+static int
+check_alpn(NKSN_Instance inst)
+{
+  gnutls_datum_t alpn;
+
+  if (gnutls_alpn_get_selected_protocol(inst->tls_session, &alpn) < 0 ||
+      alpn.size != sizeof (NKE_ALPN_NAME) - 1 ||
+      memcmp(alpn.data, NKE_ALPN_NAME, sizeof (NKE_ALPN_NAME) - 1) != 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_input_output(NKSN_Instance inst, int output)
+{
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_INPUT, !output);
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT, output);
+}
+
+/* ================================================== */
+
+static void
+change_state(NKSN_Instance inst, KeState state)
+{
+  int output;
+
+  switch (state) {
+    case KE_HANDSHAKE:
+      output = !inst->server;
+      break;
+    case KE_WAIT_CONNECT:
+    case KE_SEND:
+    case KE_SHUTDOWN:
+      output = 1;
+      break;
+    case KE_RECEIVE:
+      output = 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  set_input_output(inst, output);
+
+  inst->state = state;
+}
+
+/* ================================================== */
+
+static int
+handle_event(NKSN_Instance inst, int event)
+{
+  struct Message *message = &inst->message;
+  int r;
+
+  DEBUG_LOG("Session event %d fd=%d state=%d", event, inst->sock_fd, (int)inst->state);
+
+  switch (inst->state) {
+    case KE_WAIT_CONNECT:
+      /* Check if connect() succeeded */
+      if (event != SCH_FILE_OUTPUT)
+        return 0;
+
+      /* Get the socket error */
+      if (!SCK_GetIntOption(inst->sock_fd, SOL_SOCKET, SO_ERROR, &r))
+        r = EINVAL;
+
+      if (r != 0) {
+        LOG(LOGS_ERR, "Could not connect to %s : %s", inst->label, strerror(r));
+        stop_session(inst);
+        return 0;
+      }
+
+      DEBUG_LOG("Connected to %s", inst->label);
+
+      change_state(inst, KE_HANDSHAKE);
+      return 0;
+
+    case KE_HANDSHAKE:
+      r = gnutls_handshake(inst->tls_session);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          gnutls_datum_t cert_error;
+
+          /* Get a description of verification errors */
+          if (r != GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR ||
+              gnutls_certificate_verification_status_print(
+                          gnutls_session_get_verify_cert_status(inst->tls_session),
+                          gnutls_certificate_type_get(inst->tls_session), &cert_error, 0) < 0)
+            cert_error.data = NULL;
+
+          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+              "TLS handshake with %s failed : %s%s%s", inst->label, gnutls_strerror(r),
+              cert_error.data ? " " : "", cert_error.data ? (const char *)cert_error.data : "");
+
+          if (cert_error.data)
+            gnutls_free(cert_error.data);
+
+          stop_session(inst);
+
+          /* Increase the retry interval if the handshake did not fail due
+             to the other end closing the connection */
+          if (r != GNUTLS_E_PULL_ERROR && r != GNUTLS_E_PREMATURE_TERMINATION)
+            inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
+          return 0;
+        }
+
+        /* Disable output when the handshake is trying to receive data */
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
+        return 0;
+      }
+
+      inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
+      if (DEBUG) {
+        char *description = gnutls_session_get_desc(inst->tls_session);
+        DEBUG_LOG("Handshake with %s completed %s",
+                  inst->label, description ? description : "");
+        gnutls_free(description);
+      }
+
+      if (!check_alpn(inst)) {
+        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE not supported by %s", inst->label);
+        stop_session(inst);
+        return 0;
+      }
+
+      /* Client will send a request to the server */
+      change_state(inst, inst->server ? KE_RECEIVE : KE_SEND);
+      return 0;
+
+    case KE_SEND:
+      assert(inst->new_message && message->complete);
+      assert(message->length <= sizeof (message->data) && message->length > message->sent);
+
+      r = gnutls_record_send(inst->tls_session, &message->data[message->sent],
+                             message->length - message->sent);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+              "Could not send NTS-KE message to %s : %s", inst->label, gnutls_strerror(r));
+          stop_session(inst);
+        }
+        return 0;
+      }
+
+      DEBUG_LOG("Sent %d bytes to %s", r, inst->label);
+
+      message->sent += r;
+      if (message->sent < message->length)
+        return 0;
+
+      /* Client will receive a response */
+      change_state(inst, inst->server ? KE_SHUTDOWN : KE_RECEIVE);
+      reset_message(&inst->message);
+      inst->new_message = 0;
+      return 0;
+
+    case KE_RECEIVE:
+      do {
+        if (message->length >= sizeof (message->data)) {
+          DEBUG_LOG("Message is too long");
+          stop_session(inst);
+          return 0;
+        }
+
+        r = gnutls_record_recv(inst->tls_session, &message->data[message->length],
+                               sizeof (message->data) - message->length);
+
+        if (r < 0) {
+          /* Handle a renegotiation request on both client and server as
+             a protocol error */
+          if (gnutls_error_is_fatal(r) || r == GNUTLS_E_REHANDSHAKE) {
+            LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+                "Could not receive NTS-KE message from %s : %s",
+                inst->label, gnutls_strerror(r));
+            stop_session(inst);
+          }
+          return 0;
+        }
+
+        DEBUG_LOG("Received %d bytes from %s", r, inst->label);
+
+        message->length += r;
+
+      } while (gnutls_record_check_pending(inst->tls_session) > 0);
+
+      if (!check_message_format(message, r == 0)) {
+        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+            "Received invalid NTS-KE message from %s", inst->label);
+        stop_session(inst);
+        return 0;
+      }
+
+      /* Wait for more data if the message is not complete yet */
+      if (!message->complete)
+        return 0;
+
+      /* Server will send a response to the client */
+      change_state(inst, inst->server ? KE_SEND : KE_SHUTDOWN);
+
+      /* Return success to process the received message */
+      return 1;
+
+    case KE_SHUTDOWN:
+      r = gnutls_bye(inst->tls_session, GNUTLS_SHUT_RDWR);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          DEBUG_LOG("Shutdown with %s failed : %s", inst->label, gnutls_strerror(r));
+          stop_session(inst);
+          return 0;
+        }
+
+        /* Disable output when the TLS shutdown is trying to receive data */
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
+        return 0;
+      }
+
+      SCK_ShutdownConnection(inst->sock_fd);
+      stop_session(inst);
+
+      DEBUG_LOG("Shutdown completed");
+      return 0;
+
+    default:
+      assert(0);
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+read_write_socket(int fd, int event, void *arg)
+{
+  NKSN_Instance inst = arg;
+
+  if (!handle_event(inst, event))
+    return;
+
+  /* A valid message was received.  Call the handler to process the message,
+     and prepare a response if it is a server. */
+
+  reset_message_parsing(&inst->message);
+
+  if (!(inst->handler)(inst->handler_arg)) {
+    stop_session(inst);
+    return;
+  }
+}
+
+/* ================================================== */
+
+static time_t
+get_time(time_t *t)
+{
+  struct timespec now;
+
+  LCL_ReadCookedTime(&now, NULL);
+  if (t)
+    *t = now.tv_sec;
+
+  return now.tv_sec;
+}
+
+/* ================================================== */
+
+static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type != LCL_ChangeUnknownStep && clock_updates < INT_MAX)
+    clock_updates++;
+}
+
+/* ================================================== */
+
+static int gnutls_initialised = 0;
+
+static int
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return 1;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  /* Prepare a priority cache for server and client NTS-KE sessions
+     (the NTS specification requires TLS1.3 or later) */
+  r = gnutls_priority_init2(&priority_cache,
+                            "-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-TLS1.2:-VERS-DTLS-ALL",
+                            NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND);
+  if (r < 0) {
+    LOG(LOGS_ERR, "Could not initialise %s : %s",
+        "priority cache for TLS", gnutls_strerror(r));
+    gnutls_global_deinit();
+    return 0;
+  }
+
+  /* Use our clock instead of the system clock in certificate verification */
+  gnutls_global_set_time_function(get_time);
+
+  gnutls_initialised = 1;
+  DEBUG_LOG("Initialised");
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  if (!gnutls_initialised || credentials_counter > 0)
+    return;
+
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);
+
+  gnutls_priority_deinit(priority_cache);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static NKSN_Credentials
+create_credentials(const char **certs, const char **keys, int n_certs_keys,
+                   const char **trusted_certs, uint32_t *trusted_certs_ids,
+                   int n_trusted_certs, uint32_t trusted_cert_set)
+{
+  gnutls_certificate_credentials_t credentials = NULL;
+  int i, r;
+
+  if (!init_gnutls())
+    return NULL;
+
+  r = gnutls_certificate_allocate_credentials(&credentials);
+  if (r < 0)
+    goto error;
+
+  if (certs && keys) {
+    if (trusted_certs || trusted_certs_ids)
+      assert(0);
+
+    for (i = 0; i < n_certs_keys; i++) {
+      r = gnutls_certificate_set_x509_key_file(credentials, certs[i], keys[i],
+                                               GNUTLS_X509_FMT_PEM);
+      if (r < 0)
+        goto error;
+    }
+  } else {
+    if (certs || keys || n_certs_keys > 0)
+      assert(0);
+
+    if (trusted_cert_set == 0 && !CNF_GetNoSystemCert()) {
+      r = gnutls_certificate_set_x509_system_trust(credentials);
+      if (r < 0)
+        goto error;
+    }
+
+    if (trusted_certs && trusted_certs_ids) {
+      for (i = 0; i < n_trusted_certs; i++) {
+        struct stat buf;
+
+        if (trusted_certs_ids[i] != trusted_cert_set)
+          continue;
+
+        if (stat(trusted_certs[i], &buf) == 0 && S_ISDIR(buf.st_mode))
+          r = gnutls_certificate_set_x509_trust_dir(credentials, trusted_certs[i],
+                                                    GNUTLS_X509_FMT_PEM);
+        else
+          r = gnutls_certificate_set_x509_trust_file(credentials, trusted_certs[i],
+                                                     GNUTLS_X509_FMT_PEM);
+        if (r < 0)
+          goto error;
+
+        DEBUG_LOG("Added %d trusted certs from %s", r, trusted_certs[i]);
+      }
+    }
+  }
+
+  credentials_counter++;
+
+  return (NKSN_Credentials)credentials;
+
+error:
+  LOG(LOGS_ERR, "Could not set credentials : %s", gnutls_strerror(r));
+  if (credentials)
+    gnutls_certificate_free_credentials(credentials);
+  deinit_gnutls();
+  return NULL;
+}
+
+/* ================================================== */
+
+NKSN_Credentials
+NKSN_CreateServerCertCredentials(const char **certs, const char **keys, int n_certs_keys)
+{
+  return create_credentials(certs, keys, n_certs_keys, NULL, NULL, 0, 0);
+}
+
+/* ================================================== */
+
+NKSN_Credentials
+NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                 int n_certs_ids, uint32_t trusted_cert_set)
+{
+  return create_credentials(NULL, NULL, 0, certs, ids, n_certs_ids, trusted_cert_set);
+}
+
+/* ================================================== */
+
+void
+NKSN_DestroyCertCredentials(NKSN_Credentials credentials)
+{
+  gnutls_certificate_free_credentials((gnutls_certificate_credentials_t)credentials);
+  credentials_counter--;
+  deinit_gnutls();
+}
+
+/* ================================================== */
+
+NKSN_Instance
+NKSN_CreateInstance(int server_mode, const char *server_name,
+                    NKSN_MessageHandler handler, void *handler_arg)
+{
+  NKSN_Instance inst;
+
+  inst = MallocNew(struct NKSN_Instance_Record);
+
+  inst->server = server_mode;
+  inst->server_name = server_name ? Strdup(server_name) : NULL;
+  inst->handler = handler;
+  inst->handler_arg = handler_arg;
+  /* Replace a NULL argument with the session itself */
+  if (!inst->handler_arg)
+    inst->handler_arg = inst;
+
+  inst->state = KE_STOPPED;
+  inst->sock_fd = INVALID_SOCK_FD;
+  inst->label = NULL;
+  inst->tls_session = NULL;
+  inst->timeout_id = 0;
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NKSN_DestroyInstance(NKSN_Instance inst)
+{
+  stop_session(inst);
+
+  Free(inst->server_name);
+  Free(inst);
+}
+
+/* ================================================== */
+
+int
+NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                  NKSN_Credentials credentials, double timeout)
+{
+  assert(inst->state == KE_STOPPED);
+
+  inst->tls_session = create_tls_session(inst->server, sock_fd, inst->server_name,
+                                         (gnutls_certificate_credentials_t)credentials,
+                                         priority_cache);
+  if (!inst->tls_session)
+    return 0;
+
+  inst->sock_fd = sock_fd;
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_write_socket, inst);
+
+  inst->label = Strdup(label);
+  inst->timeout_id = SCH_AddTimeoutByDelay(timeout, session_timeout, inst);
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;
+
+  reset_message(&inst->message);
+  inst->new_message = 0;
+
+  change_state(inst, inst->server ? KE_HANDSHAKE : KE_WAIT_CONNECT);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NKSN_BeginMessage(NKSN_Instance inst)
+{
+  reset_message(&inst->message);
+  inst->new_message = 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_AddRecord(NKSN_Instance inst, int critical, int type, const void *body, int body_length)
+{
+  assert(inst->new_message && !inst->message.complete);
+  assert(type != NKE_RECORD_END_OF_MESSAGE);
+
+  return add_record(&inst->message, critical, type, body, body_length);
+}
+
+/* ================================================== */
+
+int
+NKSN_EndMessage(NKSN_Instance inst)
+{
+  assert(!inst->message.complete);
+
+  /* Terminate the message */
+  if (!add_record(&inst->message, 1, NKE_RECORD_END_OF_MESSAGE, NULL, 0))
+    return 0;
+
+  inst->message.complete = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
+               void *body, int buffer_length)
+{
+  int type2;
+
+  assert(inst->message.complete);
+
+  if (body_length)
+    *body_length = 0;
+
+  if (!get_record(&inst->message, critical, &type2, body_length, body, buffer_length))
+    return 0;
+
+  /* Hide the end-of-message record */
+  if (type2 == NKE_RECORD_END_OF_MESSAGE)
+    return 0;
+
+  if (type)
+    *type = type2;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c)
+{
+  int length = SIV_GetKeyLength(siv);
+
+  if (length <= 0 || length > sizeof (c2s->key) || length > sizeof (s2c->key)) {
+    DEBUG_LOG("Invalid algorithm");
+    return 0;
+  }
+
+  if (gnutls_prf_rfc5705(inst->tls_session,
+                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
+                         sizeof (NKE_EXPORTER_CONTEXT_C2S) - 1, NKE_EXPORTER_CONTEXT_C2S,
+                         length, (char *)c2s->key) < 0 ||
+      gnutls_prf_rfc5705(inst->tls_session,
+                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
+                         sizeof (NKE_EXPORTER_CONTEXT_S2C) - 1, NKE_EXPORTER_CONTEXT_S2C,
+                         length, (char *)s2c->key) < 0) {
+    DEBUG_LOG("Could not export key");
+    return 0;
+  }
+
+  c2s->length = length;
+  s2c->length = length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_IsStopped(NKSN_Instance inst)
+{
+  return inst->state == KE_STOPPED;
+}
+
+/* ================================================== */
+
+void
+NKSN_StopSession(NKSN_Instance inst)
+{
+  stop_session(inst);
+}
+
+/* ================================================== */
+
+int
+NKSN_GetRetryFactor(NKSN_Instance inst)
+{
+  return inst->retry_factor;
+}
diff --git a/nts_ke_session.h b/nts_ke_session.h
new file mode 100644
index 0000000..2735e04
--- /dev/null
+++ b/nts_ke_session.h
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE session
+  */
+
+#ifndef GOT_NTS_KE_SESSION_H
+#define GOT_NTS_KE_SESSION_H
+
+#include "nts_ke.h"
+#include "siv.h"
+
+typedef struct NKSN_Credentials_Record *NKSN_Credentials;
+
+typedef struct NKSN_Instance_Record *NKSN_Instance;
+
+/* Handler for received NTS-KE messages.  A zero return code stops
+   the session. */
+typedef int (*NKSN_MessageHandler)(void *arg);
+
+/* Get server or client credentials using a server certificate and key,
+   or certificates of trusted CAs.  The credentials may be shared between
+   different clients or servers. */
+extern NKSN_Credentials NKSN_CreateServerCertCredentials(const char **certs, const char **keys,
+                                                         int n_certs_keys);
+extern NKSN_Credentials NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                                         int n_certs_ids,
+                                                         uint32_t trusted_cert_set);
+
+/* Destroy the credentials */
+extern void NKSN_DestroyCertCredentials(NKSN_Credentials credentials);
+
+/* Create an instance */
+extern NKSN_Instance NKSN_CreateInstance(int server_mode, const char *server_name,
+                                         NKSN_MessageHandler handler, void *handler_arg);
+
+/* Destroy an instance */
+extern void NKSN_DestroyInstance(NKSN_Instance inst);
+
+/* Start a new NTS-KE session */
+extern int NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                             NKSN_Credentials credentials, double timeout);
+
+/* Begin an NTS-KE message.  A request should be made right after starting
+   the session and response should be made in the message handler. */
+extern void NKSN_BeginMessage(NKSN_Instance inst);
+
+/* Add a record to the message */
+extern int NKSN_AddRecord(NKSN_Instance inst, int critical, int type,
+                          const void *body, int body_length);
+
+/* Terminate the message */
+extern int NKSN_EndMessage(NKSN_Instance inst);
+
+/* Get the next record from the received message.  This function should be
+   called from the message handler. */
+extern int NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
+                          void *body, int buffer_length);
+
+/* Export NTS keys for a specified algorithm */
+extern int NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c);
+
+/* Check if the session has stopped */
+extern int NKSN_IsStopped(NKSN_Instance inst);
+
+/* Stop the session */
+extern void NKSN_StopSession(NKSN_Instance inst);
+
+/* Get a factor to calculate retry interval (in log2 seconds)
+   based on the session state or how it was terminated */
+extern int NKSN_GetRetryFactor(NKSN_Instance inst);
+
+#endif
diff --git a/nts_ntp.h b/nts_ntp.h
new file mode 100644
index 0000000..e39def2
--- /dev/null
+++ b/nts_ntp.h
@@ -0,0 +1,36 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-NTP protocol
+  */
+
+#ifndef GOT_NTS_NTP_H
+#define GOT_NTS_NTP_H
+
+#define NTP_KOD_NTS_NAK                 0x4e54534e
+
+#define NTS_MIN_UNIQ_ID_LENGTH          32
+#define NTS_MIN_UNPADDED_NONCE_LENGTH   16
+#define NTS_MAX_COOKIES                 8
+
+#endif
diff --git a/nts_ntp_auth.c b/nts_ntp_auth.c
new file mode 100644
index 0000000..ac0763e
--- /dev/null
+++ b/nts_ntp_auth.c
@@ -0,0 +1,183 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS Authenticator and Encrypted Extension Fields extension field
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_auth.h"
+
+#include "logging.h"
+#include "ntp_ext.h"
+#include "nts_ntp.h"
+#include "siv.h"
+#include "util.h"
+
+struct AuthHeader {
+  uint16_t nonce_length;
+  uint16_t ciphertext_length;
+};
+
+/* ================================================== */
+
+static int
+get_padding_length(int length)
+{
+  return length % 4U ? 4 - length % 4U : 0;
+}
+
+/* ================================================== */
+
+static int
+get_padded_length(int length)
+{
+  return length + get_padding_length(length);
+}
+
+/* ================================================== */
+
+int
+NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                   const unsigned char *nonce, int nonce_length,
+                   const unsigned char *plaintext, int plaintext_length,
+                   int min_ef_length)
+{
+  int auth_length, ciphertext_length, assoc_length;
+  int nonce_padding, ciphertext_padding, additional_padding;
+  unsigned char *ciphertext, *body;
+  struct AuthHeader *header;
+
+  assert(sizeof (*header) == 4);
+
+  if (nonce_length <= 0 || plaintext_length < 0) {
+    DEBUG_LOG("Invalid nonce/plaintext length");
+    return 0;
+  }
+
+  assoc_length = info->length;
+  ciphertext_length = SIV_GetTagLength(siv) + plaintext_length;
+  nonce_padding = get_padding_length(nonce_length);
+  ciphertext_padding = get_padding_length(ciphertext_length);
+  min_ef_length = get_padded_length(min_ef_length);
+
+  auth_length = sizeof (*header) + nonce_length + nonce_padding +
+                ciphertext_length + ciphertext_padding;
+  additional_padding = MAX(min_ef_length - auth_length - 4, 0);
+  additional_padding = MAX(NTS_MIN_UNPADDED_NONCE_LENGTH - nonce_length - nonce_padding,
+                           additional_padding);
+  auth_length += additional_padding;
+
+  if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, auth_length,
+                         (void **)&header)) {
+    DEBUG_LOG("Could not add EF");
+    return 0;
+  }
+
+  header->nonce_length = htons(nonce_length);
+  header->ciphertext_length = htons(ciphertext_length);
+
+  body = (unsigned char *)(header + 1);
+  ciphertext = body + nonce_length + nonce_padding;
+
+  if ((unsigned char *)header + auth_length !=
+      ciphertext + ciphertext_length + ciphertext_padding + additional_padding)
+    assert(0);
+
+  memcpy(body, nonce, nonce_length);
+  memset(body + nonce_length, 0, nonce_padding);
+
+  if (!SIV_Encrypt(siv, nonce, nonce_length, packet, assoc_length,
+                   plaintext, plaintext_length, ciphertext, ciphertext_length)) {
+    DEBUG_LOG("SIV encrypt failed");
+    info->length = assoc_length;
+    return 0;
+  }
+
+  memset(ciphertext + ciphertext_length, 0, ciphertext_padding + additional_padding);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv, int ef_start,
+                  unsigned char *plaintext, int buffer_length, int *plaintext_length)
+{
+  unsigned int siv_tag_length, nonce_length, ciphertext_length;
+  unsigned char *nonce, *ciphertext;
+  int ef_type, ef_body_length;
+  void *ef_body;
+  struct AuthHeader *header;
+
+  if (buffer_length < 0)
+    return 0;
+
+  if (!NEF_ParseField(packet, info->length, ef_start,
+                      NULL, &ef_type, &ef_body, &ef_body_length))
+    return 0;
+
+  if (ef_type != NTP_EF_NTS_AUTH_AND_EEF || ef_body_length < sizeof (*header))
+    return 0;
+
+  header = ef_body;
+
+  nonce_length = ntohs(header->nonce_length);
+  ciphertext_length = ntohs(header->ciphertext_length);
+
+  if (get_padded_length(nonce_length) +
+      get_padded_length(ciphertext_length) > ef_body_length)
+    return 0;
+
+  nonce = (unsigned char *)(header + 1);
+  ciphertext = nonce + get_padded_length(nonce_length);
+
+  siv_tag_length = SIV_GetTagLength(siv);
+
+  if (nonce_length < 1 ||
+      ciphertext_length < siv_tag_length ||
+      ciphertext_length - siv_tag_length > buffer_length) {
+    DEBUG_LOG("Unexpected nonce/ciphertext length");
+    return 0;
+  }
+
+  if (ef_body_length < sizeof (*header) +
+        NTS_MIN_UNPADDED_NONCE_LENGTH + get_padded_length(ciphertext_length)) {
+    DEBUG_LOG("Missing padding");
+    return 0;
+  }
+
+  *plaintext_length = ciphertext_length - siv_tag_length;
+  assert(*plaintext_length >= 0);
+
+  if (!SIV_Decrypt(siv, nonce, nonce_length, packet, ef_start,
+                   ciphertext, ciphertext_length, plaintext, *plaintext_length)) {
+    DEBUG_LOG("SIV decrypt failed");
+    return 0;
+  }
+
+  return 1;
+}
diff --git a/nts_ntp_auth.h b/nts_ntp_auth.h
new file mode 100644
index 0000000..856beb3
--- /dev/null
+++ b/nts_ntp_auth.h
@@ -0,0 +1,43 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for NTS Authenticator and Encrypted Extension Fields
+  extension field
+  */
+
+#ifndef GOT_NTS_NTP_AUTH_H
+#define GOT_NTS_NTP_AUTH_H
+
+#include "ntp.h"
+#include "siv.h"
+
+extern int NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                              const unsigned char *nonce, int nonce_length,
+                              const unsigned char *plaintext, int plaintext_length,
+                              int min_ef_length);
+
+extern int NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                             int ef_start, unsigned char *plaintext, int buffer_length,
+                             int *plaintext_length);
+
+#endif
diff --git a/nts_ntp_client.c b/nts_ntp_client.c
new file mode 100644
index 0000000..34412a6
--- /dev/null
+++ b/nts_ntp_client.c
@@ -0,0 +1,709 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Client NTS-NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_client.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp.h"
+#include "ntp_ext.h"
+#include "ntp_sources.h"
+#include "nts_ke_client.h"
+#include "nts_ntp.h"
+#include "nts_ntp_auth.h"
+#include "sched.h"
+#include "siv.h"
+#include "util.h"
+
+/* Maximum length of all cookies to avoid IP fragmentation */
+#define MAX_TOTAL_COOKIE_LENGTH (8 * 108)
+
+/* Magic string of files containing keys and cookies */
+#define DUMP_IDENTIFIER "NNC0\n"
+
+struct NNC_Instance_Record {
+  /* Address of NTS-KE server */
+  IPSockAddr nts_address;
+  /* Hostname or IP address for certificate verification */
+  char *name;
+  /* ID of trusted certificates */
+  uint32_t cert_set;
+  /* Configured NTP port */
+  uint16_t default_ntp_port;
+  /* Address of NTP server (can be negotiated in NTS-KE) */
+  IPSockAddr ntp_address;
+
+  NKC_Instance nke;
+  SIV_Instance siv;
+
+  int nke_attempts;
+  double next_nke_attempt;
+  double last_nke_success;
+
+  NKE_Context context;
+  unsigned int context_id;
+  NKE_Cookie cookies[NTS_MAX_COOKIES];
+  int num_cookies;
+  int cookie_index;
+  int auth_ready;
+  int nak_response;
+  int ok_response;
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  unsigned char uniq_id[NTS_MIN_UNIQ_ID_LENGTH];
+};
+
+/* ================================================== */
+
+static void save_cookies(NNC_Instance inst);
+static void load_cookies(NNC_Instance inst);
+
+/* ================================================== */
+
+static void
+reset_instance(NNC_Instance inst)
+{
+  if (inst->nke)
+    NKC_DestroyInstance(inst->nke);
+  inst->nke = NULL;
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;
+  inst->last_nke_success = 0.0;
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->context_id = 0;
+  memset(inst->cookies, 0, sizeof (inst->cookies));
+  inst->num_cookies = 0;
+  inst->cookie_index = 0;
+  inst->auth_ready = 0;
+  inst->nak_response = 0;
+  inst->ok_response = 1;
+  memset(inst->nonce, 0, sizeof (inst->nonce));
+  memset(inst->uniq_id, 0, sizeof (inst->uniq_id));
+}
+
+/* ================================================== */
+
+NNC_Instance
+NNC_CreateInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set, uint16_t ntp_port)
+{
+  NNC_Instance inst;
+
+  inst = MallocNew(struct NNC_Instance_Record);
+
+  inst->nts_address = *nts_address;
+  inst->name = Strdup(name);
+  inst->cert_set = cert_set;
+  inst->default_ntp_port = ntp_port;
+  inst->ntp_address.ip_addr = nts_address->ip_addr;
+  inst->ntp_address.port = ntp_port;
+  inst->siv = NULL;
+  inst->nke = NULL;
+
+  reset_instance(inst);
+
+  /* Try to reload saved keys and cookies */
+  load_cookies(inst);
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NNC_DestroyInstance(NNC_Instance inst)
+{
+  save_cookies(inst);
+
+  reset_instance(inst);
+
+  Free(inst->name);
+  Free(inst);
+}
+
+/* ================================================== */
+
+static int
+check_cookies(NNC_Instance inst)
+{
+  /* Force a new NTS-KE session if a NAK was received without a valid response,
+     or the keys encrypting the cookies need to be refreshed */
+  if (inst->num_cookies > 0 &&
+      ((inst->nak_response && !inst->ok_response) ||
+       SCH_GetLastEventMonoTime() - inst->last_nke_success > CNF_GetNtsRefresh())) {
+    inst->num_cookies = 0;
+    DEBUG_LOG("Dropped cookies");
+  }
+
+  return inst->num_cookies > 0;
+}
+
+/* ================================================== */
+
+static int
+set_ntp_address(NNC_Instance inst, NTP_Remote_Address *negotiated_address)
+{
+  NTP_Remote_Address old_address, new_address;
+
+  old_address = inst->ntp_address;
+  new_address = *negotiated_address;
+
+  if (new_address.ip_addr.family == IPADDR_UNSPEC)
+    new_address.ip_addr = inst->nts_address.ip_addr;
+  if (new_address.port == 0)
+    new_address.port = inst->default_ntp_port;
+
+  if (UTI_CompareIPs(&old_address.ip_addr, &new_address.ip_addr, NULL) == 0 &&
+      old_address.port == new_address.port)
+    /* Nothing to do */
+    return 1;
+
+  if (NSR_UpdateSourceNtpAddress(&old_address, &new_address) != NSR_Success) {
+    LOG(LOGS_ERR, "Could not change %s to negotiated address %s",
+        UTI_IPToString(&old_address.ip_addr), UTI_IPToString(&new_address.ip_addr));
+    return 0;
+  }
+
+  inst->ntp_address = new_address;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+update_next_nke_attempt(NNC_Instance inst, double now)
+{
+  int factor, interval;
+
+  if (!inst->nke)
+    return;
+
+  factor = NKC_GetRetryFactor(inst->nke);
+  interval = MIN(factor + inst->nke_attempts - 1, NKE_MAX_RETRY_INTERVAL2);
+  inst->next_nke_attempt = now + UTI_Log2ToDouble(interval);
+}
+
+/* ================================================== */
+
+static int
+get_cookies(NNC_Instance inst)
+{
+  NTP_Remote_Address ntp_address;
+  double now;
+  int got_data;
+
+  assert(inst->num_cookies == 0);
+
+  now = SCH_GetLastEventMonoTime();
+
+  /* Create and start a new NTS-KE session if not already present */
+  if (!inst->nke) {
+    if (now < inst->next_nke_attempt) {
+      DEBUG_LOG("Limiting NTS-KE request rate (%f seconds)",
+                inst->next_nke_attempt - now);
+      return 0;
+    }
+
+    inst->nke = NKC_CreateInstance(&inst->nts_address, inst->name, inst->cert_set);
+
+    inst->nke_attempts++;
+    update_next_nke_attempt(inst, now);
+
+    if (!NKC_Start(inst->nke))
+      return 0;
+  }
+
+  update_next_nke_attempt(inst, now);
+
+  /* Wait until the session stops */
+  if (NKC_IsActive(inst->nke))
+    return 0;
+
+  assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
+  /* Get the new keys, cookies and NTP address if the session was successful */
+  got_data = NKC_GetNtsData(inst->nke, &inst->context,
+                            inst->cookies, &inst->num_cookies, NTS_MAX_COOKIES,
+                            &ntp_address);
+
+  NKC_DestroyInstance(inst->nke);
+  inst->nke = NULL;
+
+  if (!got_data)
+    return 0;
+
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->context_id++;
+
+  /* Force a new session if the NTP address is used by another source, with
+     an expectation that it will eventually get a non-conflicting address */
+  if (!set_ntp_address(inst, &ntp_address)) {
+    inst->num_cookies = 0;
+    return 0;
+  }
+
+  inst->last_nke_success = now;
+  inst->cookie_index = 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNC_PrepareForAuth(NNC_Instance inst)
+{
+  inst->auth_ready = 0;
+
+  /* Prepare data for the next request and invalidate any responses to the
+     previous request */
+  UTI_GetRandomBytes(inst->uniq_id, sizeof (inst->uniq_id));
+  UTI_GetRandomBytes(inst->nonce, sizeof (inst->nonce));
+
+  /* Get new cookies if there are not any, or they are no longer usable */
+  if (!check_cookies(inst)) {
+    if (!get_cookies(inst))
+      return 0;
+  }
+
+  inst->nak_response = 0;
+
+  if (!inst->siv)
+    inst->siv = SIV_CreateInstance(inst->context.algorithm);
+
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.c2s.key, inst->context.c2s.length)) {
+    DEBUG_LOG("Could not set SIV key");
+    return 0;
+  }
+
+  inst->auth_ready = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
+                        NTP_PacketInfo *info)
+{
+  NKE_Cookie *cookie;
+  int i, req_cookies;
+  void *ef_body;
+
+  if (!inst->auth_ready)
+    return 0;
+
+  inst->auth_ready = 0;
+
+  if (inst->num_cookies <= 0 || !inst->siv)
+    return 0;
+
+  if (info->mode != MODE_CLIENT)
+    return 0;
+
+  cookie = &inst->cookies[inst->cookie_index];
+  inst->num_cookies--;
+  inst->cookie_index = (inst->cookie_index + 1) % NTS_MAX_COOKIES;
+
+  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies,
+                    MAX_TOTAL_COOKIE_LENGTH / (cookie->length + 4));
+
+  if (!NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER,
+                    inst->uniq_id, sizeof (inst->uniq_id)))
+    return 0;
+
+  if (!NEF_AddField(packet, info, NTP_EF_NTS_COOKIE,
+                    cookie->cookie, cookie->length))
+    return 0;
+
+  for (i = 0; i < req_cookies - 1; i++) {
+    if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
+                           cookie->length, &ef_body))
+      return 0;
+    memset(ef_body, 0, cookie->length);
+  }
+
+  if (!NNA_GenerateAuthEF(packet, info, inst->siv, inst->nonce, sizeof (inst->nonce),
+                          (const unsigned char *)"", 0, NTP_MAX_V4_MAC_LENGTH + 4))
+    return 0;
+
+  inst->ok_response = 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_encrypted_efs(NNC_Instance inst, unsigned char *plaintext, int length)
+{
+  int ef_length, parsed;
+
+  for (parsed = 0; parsed < length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, length, parsed, &ef_length, NULL, NULL, NULL)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+extract_cookies(NNC_Instance inst, unsigned char *plaintext, int length)
+{
+  int ef_type, ef_body_length, ef_length, parsed, index, acceptable, saved;
+  void *ef_body;
+
+  acceptable = saved = 0;
+
+  for (parsed = 0; parsed < length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, length, parsed,
+                              &ef_length, &ef_type, &ef_body, &ef_body_length))
+      return 0;
+
+    if (ef_type != NTP_EF_NTS_COOKIE)
+      continue;
+
+    if (ef_length < NTP_MIN_EF_LENGTH || ef_body_length > sizeof (inst->cookies[0].cookie)) {
+      DEBUG_LOG("Unexpected cookie length %d", ef_body_length);
+      continue;
+    }
+
+    acceptable++;
+
+    if (inst->num_cookies >= NTS_MAX_COOKIES)
+      continue;
+
+    index = (inst->cookie_index + inst->num_cookies) % NTS_MAX_COOKIES;
+    assert(index >= 0 && index < NTS_MAX_COOKIES);
+    assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
+    memcpy(inst->cookies[index].cookie, ef_body, ef_body_length);
+    inst->cookies[index].length = ef_body_length;
+    inst->num_cookies++;
+
+    saved++;
+  }
+
+  DEBUG_LOG("Extracted %d cookies (saved %d)", acceptable, saved);
+
+  return acceptable > 0;
+}
+
+/* ================================================== */
+
+int
+NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
+                      NTP_PacketInfo *info)
+{
+  int ef_type, ef_body_length, ef_length, parsed, plaintext_length;
+  int has_valid_uniq_id = 0, has_valid_auth = 0;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  void *ef_body;
+
+  if (info->ext_fields == 0 || info->mode != MODE_SERVER)
+    return 0;
+
+  /* Accept at most one response per request */
+  if (inst->ok_response || inst->auth_ready)
+    return 0;
+
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.s2c.key, inst->context.s2c.length)) {
+    DEBUG_LOG("Could not set SIV key");
+    return 0;
+  }
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed parsing */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        if (ef_body_length != sizeof (inst->uniq_id) ||
+            memcmp(ef_body, inst->uniq_id, sizeof (inst->uniq_id)) != 0) {
+          DEBUG_LOG("Invalid uniq id");
+          return 0;
+        }
+        has_valid_uniq_id = 1;
+        break;
+      case NTP_EF_NTS_COOKIE:
+        DEBUG_LOG("Unencrypted cookie");
+        break;
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        if (parsed + ef_length != info->length) {
+          DEBUG_LOG("Auth not last EF");
+          return 0;
+        }
+
+        if (!NNA_DecryptAuthEF(packet, info, inst->siv, parsed,
+                               plaintext, sizeof (plaintext), &plaintext_length))
+          return 0;
+
+        if (!parse_encrypted_efs(inst, plaintext, plaintext_length))
+          return 0;
+
+        has_valid_auth = 1;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!has_valid_uniq_id || !has_valid_auth) {
+    if (has_valid_uniq_id && packet->stratum == NTP_INVALID_STRATUM &&
+        ntohl(packet->reference_id) == NTP_KOD_NTS_NAK) {
+      DEBUG_LOG("NTS NAK");
+      inst->nak_response = 1;
+      return 0;
+    }
+
+    DEBUG_LOG("Missing NTS EF");
+    return 0;
+  }
+
+  if (!extract_cookies(inst, plaintext, plaintext_length))
+    return 0;
+
+  inst->ok_response = 1;
+
+  /* At this point we know the client interoperates with the server.  Allow a
+     new NTS-KE session to be started as soon as the cookies run out. */
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NNC_ChangeAddress(NNC_Instance inst, IPAddr *address)
+{
+  save_cookies(inst);
+
+  inst->nts_address.ip_addr = *address;
+  inst->ntp_address.ip_addr = *address;
+
+  reset_instance(inst);
+
+  DEBUG_LOG("NTS reset");
+
+  load_cookies(inst);
+}
+
+/* ================================================== */
+
+static void
+save_cookies(NNC_Instance inst)
+{
+  char buf[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename;
+  struct timespec now;
+  double context_time;
+  FILE *f;
+  int i;
+
+  if (inst->num_cookies < 1 || !UTI_IsIPReal(&inst->nts_address.ip_addr))
+    return;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".tmp", 'w', 0600);
+  if (!f)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time = inst->last_nke_success - SCH_GetLastEventMonoTime();
+  context_time += UTI_TimespecToDouble(&now);
+
+  if (fprintf(f, "%s%s\n%.1f\n%s %d\n%u %d ",
+              DUMP_IDENTIFIER, inst->name, context_time,
+              UTI_IPToString(&inst->ntp_address.ip_addr), inst->ntp_address.port,
+              inst->context_id, (int)inst->context.algorithm) < 0 ||
+      !UTI_BytesToHex(inst->context.s2c.key, inst->context.s2c.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s ", buf) < 0 ||
+      !UTI_BytesToHex(inst->context.c2s.key, inst->context.c2s.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s\n", buf) < 0)
+    goto error;
+
+  for (i = 0; i < inst->num_cookies; i++) {
+    if (!UTI_BytesToHex(inst->cookies[i].cookie, inst->cookies[i].length, buf, sizeof (buf)) ||
+        fprintf(f, "%s\n", buf) < 0)
+      goto error;
+  }
+
+  fclose(f);
+
+  if (!UTI_RenameTempFile(dump_dir, filename, ".tmp", ".nts"))
+    ;
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "save", filename);
+  fclose(f);
+
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 4
+
+static void
+load_cookies(NNC_Instance inst)
+{
+  char line[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename, *words[MAX_WORDS];
+  unsigned int context_id;
+  int i, algorithm, port;
+  double context_time;
+  struct timespec now;
+  IPSockAddr ntp_addr;
+  FILE *f;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".nts", 'r', 0);
+  if (!f)
+    return;
+
+  /* Don't load this file again */
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        strcmp(words[0], inst->name) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        sscanf(words[0], "%lf", &context_time) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 2 ||
+        !UTI_StringToIP(words[0], &ntp_addr.ip_addr) || sscanf(words[1], "%d", &port) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 4 ||
+        sscanf(words[0], "%u", &context_id) != 1 || sscanf(words[1], "%d", &algorithm) != 1)
+    goto error;
+
+  inst->context.algorithm = algorithm;
+  inst->context.s2c.length = UTI_HexToBytes(words[2], inst->context.s2c.key,
+                                            sizeof (inst->context.s2c.key));
+  inst->context.c2s.length = UTI_HexToBytes(words[3], inst->context.c2s.key,
+                                            sizeof (inst->context.c2s.key));
+
+  if (inst->context.s2c.length != SIV_GetKeyLength(algorithm) ||
+      inst->context.c2s.length != inst->context.s2c.length)
+    goto error;
+
+  for (i = 0; i < NTS_MAX_COOKIES && fgets(line, sizeof (line), f); i++) {
+    if (UTI_SplitString(line, words, MAX_WORDS) != 1)
+      goto error;
+
+    inst->cookies[i].length = UTI_HexToBytes(words[0], inst->cookies[i].cookie,
+                                             sizeof (inst->cookies[i].cookie));
+    if (inst->cookies[i].length == 0)
+      goto error;
+  }
+
+  inst->num_cookies = i;
+
+  ntp_addr.port = port;
+  if (!set_ntp_address(inst, &ntp_addr))
+    goto error;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time -= UTI_TimespecToDouble(&now);
+  if (context_time > 0)
+    context_time = 0;
+  inst->last_nke_success = context_time + SCH_GetLastEventMonoTime();
+  inst->context_id = context_id;
+
+  fclose(f);
+
+  DEBUG_LOG("Loaded %d cookies for %s", i, filename);
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "load", filename);
+  fclose(f);
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->num_cookies = 0;
+}
+
+/* ================================================== */
+
+void
+NNC_DumpData(NNC_Instance inst)
+{
+  save_cookies(inst);
+}
+
+/* ================================================== */
+
+void
+NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report)
+{
+  report->key_id = inst->context_id;
+  report->key_type = inst->context.algorithm;
+  report->key_length = 8 * inst->context.s2c.length;
+  report->ke_attempts = inst->nke_attempts;
+  if (report->key_length > 0)
+    report->last_ke_ago = SCH_GetLastEventMonoTime() - inst->last_nke_success;
+  else
+    report->last_ke_ago = -1;
+  report->cookies = inst->num_cookies;
+  report->cookie_length = inst->num_cookies > 0 ? inst->cookies[inst->cookie_index].length : 0;
+  report->nak = inst->nak_response;
+}
diff --git a/nts_ntp_client.h b/nts_ntp_client.h
new file mode 100644
index 0000000..2c314cc
--- /dev/null
+++ b/nts_ntp_client.h
@@ -0,0 +1,51 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for client NTS-NTP authentication
+  */
+
+#ifndef GOT_NTS_NTP_CLIENT_H
+#define GOT_NTS_NTP_CLIENT_H
+
+#include "addressing.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef struct NNC_Instance_Record *NNC_Instance;
+
+extern NNC_Instance NNC_CreateInstance(IPSockAddr *nts_address, const char *name,
+                                       uint32_t cert_set, uint16_t ntp_port);
+extern void NNC_DestroyInstance(NNC_Instance inst);
+extern int NNC_PrepareForAuth(NNC_Instance inst);
+extern int NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
+                                   NTP_PacketInfo *info);
+extern int NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
+                                 NTP_PacketInfo *info);
+
+extern void NNC_ChangeAddress(NNC_Instance inst, IPAddr *address);
+
+extern void NNC_DumpData(NNC_Instance inst);
+
+extern void NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report);
+
+#endif
diff --git a/nts_ntp_server.c b/nts_ntp_server.c
new file mode 100644
index 0000000..9226c89
--- /dev/null
+++ b/nts_ntp_server.c
@@ -0,0 +1,283 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Server NTS-NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_server.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp.h"
+#include "ntp_ext.h"
+#include "nts_ke_server.h"
+#include "nts_ntp.h"
+#include "nts_ntp_auth.h"
+#include "siv.h"
+#include "util.h"
+
+#define SERVER_SIV AEAD_AES_SIV_CMAC_256
+
+struct NtsServer {
+  SIV_Instance siv;
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  NKE_Cookie cookies[NTS_MAX_COOKIES];
+  int num_cookies;
+  NTP_int64 req_tx;
+};
+
+/* The server instance handling all requests */
+struct NtsServer *server;
+
+/* ================================================== */
+
+void
+NNS_Initialise(void)
+{
+  const char **certs, **keys;
+
+  /* Create an NTS-NTP server instance only if NTS-KE server is enabled */
+  if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0) {
+    server = NULL;
+    return;
+  }
+
+  server = Malloc(sizeof (struct NtsServer));
+  server->siv = SIV_CreateInstance(SERVER_SIV);
+  if (!server->siv)
+    LOG_FATAL("Could not initialise SIV cipher");
+}
+
+/* ================================================== */
+
+void
+NNS_Finalise(void)
+{
+  if (!server)
+    return;
+
+  SIV_DestroyInstance(server->siv);
+  Free(server);
+  server = NULL;
+}
+
+/* ================================================== */
+
+int
+NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
+{
+  int ef_type, ef_body_length, ef_length, has_uniq_id = 0, has_auth = 0, has_cookie = 0;
+  int i, plaintext_length, parsed, requested_cookies, cookie_length = -1, auth_start = 0;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  NKE_Context context;
+  NKE_Cookie cookie;
+  void *ef_body;
+
+  *kod = 0;
+
+  if (!server)
+    return 0;
+
+  server->num_cookies = 0;
+  server->req_tx = packet->transmit_ts;
+
+  if (info->ext_fields == 0 || info->mode != MODE_CLIENT)
+    return 0;
+
+  requested_cookies = 0;
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed NAU_ParsePacket() */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        has_uniq_id = 1;
+        break;
+      case NTP_EF_NTS_COOKIE:
+        if (has_cookie || ef_body_length > sizeof (cookie.cookie)) {
+          DEBUG_LOG("Unexpected cookie/length");
+          return 0;
+        }
+        cookie.length = ef_body_length;
+        memcpy(cookie.cookie, ef_body, ef_body_length);
+        has_cookie = 1;
+        /* Fall through */
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+        requested_cookies++;
+
+        if (cookie_length >= 0 && cookie_length != ef_body_length) {
+          DEBUG_LOG("Invalid cookie/placeholder length");
+          return 0;
+        }
+        cookie_length = ef_body_length;
+        break;
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        if (parsed + ef_length != info->length) {
+          DEBUG_LOG("Auth not last EF");
+          return 0;
+        }
+
+        auth_start = parsed;
+        has_auth = 1;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!has_uniq_id || !has_cookie || !has_auth) {
+    DEBUG_LOG("Missing an NTS EF");
+    return 0;
+  }
+
+  if (!NKS_DecodeCookie(&cookie, &context)) {
+    *kod = NTP_KOD_NTS_NAK;
+    return 0;
+  }
+
+  if (context.algorithm != SERVER_SIV) {
+    DEBUG_LOG("Unexpected SIV");
+    return 0;
+  }
+
+  if (!SIV_SetKey(server->siv, context.c2s.key, context.c2s.length)) {
+    DEBUG_LOG("Could not set C2S key");
+    return 0;
+  }
+
+  if (!NNA_DecryptAuthEF(packet, info, server->siv, auth_start,
+                         plaintext, sizeof (plaintext), &plaintext_length)) {
+    *kod = NTP_KOD_NTS_NAK;
+    return 0;
+  }
+
+  for (parsed = 0; parsed < plaintext_length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, plaintext_length, parsed,
+                              &ef_length, &ef_type, &ef_body, &ef_body_length)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }
+
+    switch (ef_type) {
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+        if (cookie_length != ef_body_length) {
+          DEBUG_LOG("Invalid cookie/placeholder length");
+          return 0;
+        }
+        requested_cookies++;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!SIV_SetKey(server->siv, context.s2c.key, context.s2c.length)) {
+    DEBUG_LOG("Could not set S2C key");
+    return 0;
+  }
+
+  /* Prepare data for NNS_GenerateResponseAuth() to minimise the time spent
+     there (when the TX timestamp is already set) */
+
+  UTI_GetRandomBytes(server->nonce, sizeof (server->nonce));
+
+  assert(sizeof (server->cookies) / sizeof (server->cookies[0]) == NTS_MAX_COOKIES);
+  for (i = 0; i < NTS_MAX_COOKIES && i < requested_cookies; i++)
+    if (!NKS_GenerateCookie(&context, &server->cookies[i]))
+      return 0;
+
+  server->num_cookies = i;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                         NTP_Packet *response, NTP_PacketInfo *res_info,
+                         uint32_t kod)
+{
+  int i, ef_type, ef_body_length, ef_length, parsed;
+  void *ef_body;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  int plaintext_length;
+
+  if (!server || req_info->mode != MODE_CLIENT || res_info->mode != MODE_SERVER)
+    return 0;
+
+  /* Make sure this is a response to the request from the last call
+     of NNS_CheckRequestAuth() */
+  if (UTI_CompareNtp64(&server->req_tx, &request->transmit_ts) != 0)
+    assert(0);
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < req_info->length; parsed += ef_length) {
+    if (!NEF_ParseField(request, req_info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed parsing */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        /* Copy the ID from the request */
+        if (!NEF_AddField(response, res_info, ef_type, ef_body, ef_body_length))
+          return 0;
+      default:
+        break;
+    }
+  }
+
+  /* NTS NAK response does not have any other fields */
+  if (kod)
+    return 1;
+
+  for (i = 0, plaintext_length = 0; i < server->num_cookies; i++) {
+    if (!NEF_SetField(plaintext, sizeof (plaintext), plaintext_length,
+                      NTP_EF_NTS_COOKIE, server->cookies[i].cookie,
+                      server->cookies[i].length, &ef_length))
+      return 0;
+
+    plaintext_length += ef_length;
+    assert(plaintext_length <= sizeof (plaintext));
+  }
+
+  server->num_cookies = 0;
+
+  /* Generate an authenticator field which will make the length
+     of the response equal to the length of the request */
+  if (!NNA_GenerateAuthEF(response, res_info, server->siv,
+                          server->nonce, sizeof (server->nonce),
+                          plaintext, plaintext_length,
+                          req_info->length - res_info->length))
+    return 0;
+
+  return 1;
+}
diff --git a/nts_ntp_server.h b/nts_ntp_server.h
new file mode 100644
index 0000000..fea28f2
--- /dev/null
+++ b/nts_ntp_server.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for server NTS-NTP authentication
+  */
+
+#ifndef GOT_NTS_NTP_SERVER_H
+#define GOT_NTS_NTP_SERVER_H
+
+#include "ntp.h"
+
+extern void NNS_Initialise(void);
+extern void NNS_Finalise(void);
+
+extern int NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod);
+extern int NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                                    NTP_Packet *response, NTP_PacketInfo *res_info,
+                                    uint32_t kod);
+
+#endif
diff --git a/pktlength.c b/pktlength.c
new file mode 100644
index 0000000..642e477
--- /dev/null
+++ b/pktlength.c
@@ -0,0 +1,220 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines to compute the expected length of a command or reply packet.
+  These operate on the RAW NETWORK packets, from the point of view of
+  integer endianness within the structures.
+
+  */
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "util.h"
+#include "pktlength.h"
+
+#define PADDING_LENGTH_(request_length, reply_length) \
+  (uint16_t)((request_length) < (reply_length) ? (reply_length) - (request_length) : 0)
+
+#define PADDING_LENGTH(request_data, reply_data) \
+  PADDING_LENGTH_(offsetof(CMD_Request, request_data), offsetof(CMD_Reply, reply_data))
+
+#define REQ_LENGTH_ENTRY(request_data_field, reply_data_field) \
+  { offsetof(CMD_Request, data.request_data_field.EOR), \
+    PADDING_LENGTH(data.request_data_field.EOR, data.reply_data_field.EOR) }
+
+#define RPY_LENGTH_ENTRY(reply_data_field) \
+  offsetof(CMD_Reply, data.reply_data_field.EOR)
+
+/* ================================================== */
+
+struct request_length {
+  uint16_t command;
+  uint16_t padding;
+};
+
+static const struct request_length request_lengths[] = {
+  REQ_LENGTH_ENTRY(null, null),                 /* NULL */
+  REQ_LENGTH_ENTRY(online, null),               /* ONLINE */
+  REQ_LENGTH_ENTRY(offline, null),              /* OFFLINE */
+  REQ_LENGTH_ENTRY(burst, null),                /* BURST */
+  REQ_LENGTH_ENTRY(modify_minpoll, null),       /* MODIFY_MINPOLL */
+  REQ_LENGTH_ENTRY(modify_maxpoll, null),       /* MODIFY_MAXPOLL */
+  REQ_LENGTH_ENTRY(dump, null),                 /* DUMP */
+  REQ_LENGTH_ENTRY(modify_maxdelay, null),      /* MODIFY_MAXDELAY */
+  REQ_LENGTH_ENTRY(modify_maxdelayratio, null), /* MODIFY_MAXDELAYRATIO */
+  REQ_LENGTH_ENTRY(modify_maxupdateskew, null), /* MODIFY_MAXUPDATESKEW */
+  REQ_LENGTH_ENTRY(logon, null),                /* LOGON */
+  REQ_LENGTH_ENTRY(settime, manual_timestamp),  /* SETTIME */
+  { 0, 0 },                                     /* LOCAL */
+  REQ_LENGTH_ENTRY(manual, null),               /* MANUAL */
+  REQ_LENGTH_ENTRY(null, n_sources),            /* N_SOURCES */
+  REQ_LENGTH_ENTRY(source_data, source_data),   /* SOURCE_DATA */
+  REQ_LENGTH_ENTRY(null, null),                 /* REKEY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* ALLOW */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* ALLOWALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* DENY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* DENYALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDALLOW */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDALLOWALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDDENY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDDENYALL */
+  REQ_LENGTH_ENTRY(ac_check, null),             /* ACCHECK */
+  REQ_LENGTH_ENTRY(ac_check, null),             /* CMDACCHECK */
+  { 0, 0 },                                     /* ADD_SERVER */
+  { 0, 0 },                                     /* ADD_PEER */
+  REQ_LENGTH_ENTRY(del_source, null),           /* DEL_SOURCE */
+  REQ_LENGTH_ENTRY(null, null),                 /* WRITERTC */
+  REQ_LENGTH_ENTRY(dfreq, null),                /* DFREQ */
+  { 0, 0 },                                     /* DOFFSET - not supported */
+  REQ_LENGTH_ENTRY(null, tracking),             /* TRACKING */
+  REQ_LENGTH_ENTRY(sourcestats, sourcestats),   /* SOURCESTATS */
+  REQ_LENGTH_ENTRY(null, rtc),                  /* RTCREPORT */
+  REQ_LENGTH_ENTRY(null, null),                 /* TRIMRTC */
+  REQ_LENGTH_ENTRY(null, null),                 /* CYCLELOGS */
+  { 0, 0 },                                     /* SUBNETS_ACCESSED - not supported */
+  { 0, 0 },                                     /* CLIENT_ACCESSES - not supported */
+  { 0, 0 },                                     /* CLIENT_ACCESSES_BY_INDEX - not supported */
+  REQ_LENGTH_ENTRY(null, manual_list),          /* MANUAL_LIST */
+  REQ_LENGTH_ENTRY(manual_delete, null),        /* MANUAL_DELETE */
+  REQ_LENGTH_ENTRY(null, null),                 /* MAKESTEP */
+  REQ_LENGTH_ENTRY(null, activity),             /* ACTIVITY */
+  REQ_LENGTH_ENTRY(modify_minstratum, null),    /* MODIFY_MINSTRATUM */
+  REQ_LENGTH_ENTRY(modify_polltarget, null),    /* MODIFY_POLLTARGET */
+  REQ_LENGTH_ENTRY(modify_maxdelaydevratio, null), /* MODIFY_MAXDELAYDEVRATIO */
+  REQ_LENGTH_ENTRY(null, null),                 /* RESELECT */
+  REQ_LENGTH_ENTRY(reselect_distance, null),    /* RESELECTDISTANCE */
+  REQ_LENGTH_ENTRY(modify_makestep, null),      /* MODIFY_MAKESTEP */
+  REQ_LENGTH_ENTRY(null, smoothing),            /* SMOOTHING */
+  REQ_LENGTH_ENTRY(smoothtime, null),           /* SMOOTHTIME */
+  REQ_LENGTH_ENTRY(null, null),                 /* REFRESH */
+  REQ_LENGTH_ENTRY(null, server_stats),         /* SERVER_STATS */
+  { 0, 0 },                                     /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
+  REQ_LENGTH_ENTRY(local, null),                /* LOCAL2 */
+  REQ_LENGTH_ENTRY(ntp_data, ntp_data),         /* NTP_DATA */
+  { 0, 0 },                                     /* ADD_SERVER2 */
+  { 0, 0 },                                     /* ADD_PEER2 */
+  { 0, 0 },                                     /* ADD_SERVER3 */
+  { 0, 0 },                                     /* ADD_PEER3 */
+  REQ_LENGTH_ENTRY(null, null),                 /* SHUTDOWN */
+  REQ_LENGTH_ENTRY(null, null),                 /* ONOFFLINE */
+  REQ_LENGTH_ENTRY(ntp_source, null),           /* ADD_SOURCE */
+  REQ_LENGTH_ENTRY(ntp_source_name,
+                   ntp_source_name),            /* NTP_SOURCE_NAME */
+  REQ_LENGTH_ENTRY(null, null),                 /* RESET_SOURCES */
+  REQ_LENGTH_ENTRY(auth_data, auth_data),       /* AUTH_DATA */
+  REQ_LENGTH_ENTRY(client_accesses_by_index,
+                   client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  REQ_LENGTH_ENTRY(select_data, select_data),   /* SELECT_DATA */
+  REQ_LENGTH_ENTRY(null, null),                 /* RELOAD_SOURCES */
+  REQ_LENGTH_ENTRY(doffset, null),              /* DOFFSET2 */
+};
+
+static const uint16_t reply_lengths[] = {
+  0,                                            /* empty slot */
+  RPY_LENGTH_ENTRY(null),                       /* NULL */
+  RPY_LENGTH_ENTRY(n_sources),                  /* N_SOURCES */
+  RPY_LENGTH_ENTRY(source_data),                /* SOURCE_DATA */
+  0,                                            /* MANUAL_TIMESTAMP */
+  RPY_LENGTH_ENTRY(tracking),                   /* TRACKING */
+  RPY_LENGTH_ENTRY(sourcestats),                /* SOURCESTATS */
+  RPY_LENGTH_ENTRY(rtc),                        /* RTC */
+  0,                                            /* SUBNETS_ACCESSED - not supported */
+  0,                                            /* CLIENT_ACCESSES - not supported */
+  0,                                            /* CLIENT_ACCESSES_BY_INDEX - not supported */
+  0,                                            /* MANUAL_LIST - not supported */
+  RPY_LENGTH_ENTRY(activity),                   /* ACTIVITY */
+  RPY_LENGTH_ENTRY(smoothing),                  /* SMOOTHING */
+  0,                                            /* SERVER_STATS - not supported */
+  0,                                            /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
+  RPY_LENGTH_ENTRY(ntp_data),                   /* NTP_DATA */
+  RPY_LENGTH_ENTRY(manual_timestamp),           /* MANUAL_TIMESTAMP2 */
+  RPY_LENGTH_ENTRY(manual_list),                /* MANUAL_LIST2 */
+  RPY_LENGTH_ENTRY(ntp_source_name),            /* NTP_SOURCE_NAME */
+  RPY_LENGTH_ENTRY(auth_data),                  /* AUTH_DATA */
+  RPY_LENGTH_ENTRY(client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  0,                                            /* SERVER_STATS2 - not supported */
+  RPY_LENGTH_ENTRY(select_data),                /* SELECT_DATA */
+  RPY_LENGTH_ENTRY(server_stats),               /* SERVER_STATS3 */
+};
+
+/* ================================================== */
+
+int
+PKL_CommandLength(CMD_Request *r)
+{
+  uint32_t type;
+  int command_length;
+
+  assert(sizeof (request_lengths) / sizeof (request_lengths[0]) == N_REQUEST_TYPES);
+
+  type = ntohs(r->command);
+  if (type >= N_REQUEST_TYPES)
+    return 0;
+
+  command_length = request_lengths[type].command;
+  if (!command_length)
+    return 0;
+
+  return command_length + PKL_CommandPaddingLength(r);
+}
+
+/* ================================================== */
+
+int
+PKL_CommandPaddingLength(CMD_Request *r)
+{
+  uint32_t type;
+
+  if (r->version < PROTO_VERSION_PADDING)
+    return 0;
+
+  type = ntohs(r->command);
+
+  if (type >= N_REQUEST_TYPES)
+    return 0;
+
+  return request_lengths[ntohs(r->command)].padding;
+}
+
+/* ================================================== */
+
+int
+PKL_ReplyLength(CMD_Reply *r)
+{
+  uint32_t type;
+
+  assert(sizeof (reply_lengths) / sizeof (reply_lengths[0]) == N_REPLY_TYPES);
+
+  type = ntohs(r->reply);
+
+  /* Note that reply type codes start from 1, not 0 */
+  if (type < 1 || type >= N_REPLY_TYPES)
+    return 0;
+
+  return reply_lengths[type];
+}
+
+/* ================================================== */
+
diff --git a/pktlength.h b/pktlength.h
new file mode 100644
index 0000000..fad4c30
--- /dev/null
+++ b/pktlength.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for pktlength.c, routines for working out the expected length
+  of a network command/reply packet.
+
+  */
+
+#ifndef GOT_PKTLENGTH_H
+#define GOT_PKTLENGTH_H
+
+#include "candm.h"
+
+extern int PKL_CommandLength(CMD_Request *r);
+
+extern int PKL_CommandPaddingLength(CMD_Request *r);
+
+extern int PKL_ReplyLength(CMD_Reply *r);
+
+#endif /* GOT_PKTLENGTH_H */
diff --git a/privops.c b/privops.c
new file mode 100644
index 0000000..3fb5cbd
--- /dev/null
+++ b/privops.c
@@ -0,0 +1,696 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ * Copyright (C) Miroslav Lichvar  2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "nameserv.h"
+#include "logging.h"
+#include "privops.h"
+#include "socket.h"
+#include "util.h"
+
+#define OP_ADJUSTTIME     1024
+#define OP_ADJUSTTIMEX    1025
+#define OP_SETTIME        1026
+#define OP_BINDSOCKET     1027
+#define OP_NAME2IPADDRESS 1028
+#define OP_RELOADDNS      1029
+#define OP_QUIT           1099
+
+union sockaddr_in46 {
+  struct sockaddr_in in4;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 in6;
+#endif
+  struct sockaddr u;
+};
+
+/* daemon request structs */
+
+typedef struct {
+  struct timeval tv;
+} ReqAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ReqAdjustTimex;
+#endif
+
+typedef struct {
+  struct timeval tv;
+} ReqSetTime;
+
+typedef struct {
+  int sock;
+  socklen_t sa_len;
+  union sockaddr_in46 sa;
+} ReqBindSocket;
+
+typedef struct {
+  char name[256];
+} ReqName2IPAddress;
+
+typedef struct {
+  int op;
+  union {
+    ReqAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ReqAdjustTimex adjust_timex;
+#endif
+    ReqSetTime set_time;
+    ReqBindSocket bind_socket;
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ReqName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvRequest;
+
+/* helper response structs */
+
+typedef struct {
+  struct timeval tv;
+} ResAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ResAdjustTimex;
+#endif
+
+typedef struct {
+  IPAddr addresses[DNS_MAX_ADDRESSES];
+} ResName2IPAddress;
+
+typedef struct {
+  char msg[256];
+} ResFatalMsg;
+
+typedef struct {
+  int fatal_error;
+  int rc;
+  int res_errno;
+  union {
+    ResFatalMsg fatal_msg;
+    ResAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ResAdjustTimex adjust_timex;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ResName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvResponse;
+
+static int helper_fd;
+static pid_t helper_pid;
+
+static int
+have_helper(void)
+{
+  return helper_fd >= 0;
+}
+
+/* ======================================================================= */
+
+/* HELPER - prepare fatal error for daemon */
+static void
+res_fatal(PrvResponse *res, const char *fmt, ...)
+{
+  va_list ap;
+
+  res->fatal_error = 1;
+  va_start(ap, fmt);
+  vsnprintf(res->data.fatal_msg.msg, sizeof (res->data.fatal_msg.msg), fmt, ap);
+  va_end(ap);
+}
+
+/* ======================================================================= */
+
+/* HELPER - send response to the fd */
+
+static int
+send_response(int fd, const PrvResponse *res)
+{
+  if (SCK_Send(fd, res, sizeof (*res), 0) != sizeof (*res))
+    return 0;
+
+  return 1;
+}
+
+/* ======================================================================= */
+/* receive daemon request plus optional file descriptor over a unix socket */
+
+static int
+receive_from_daemon(int fd, PrvRequest *req)
+{
+  SCK_Message *message;
+
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message || message->length != sizeof (*req))
+    return 0;
+
+  memcpy(req, message->data, sizeof (*req));
+
+  if (req->op == OP_BINDSOCKET) {
+    req->data.bind_socket.sock = message->descriptor;
+
+    /* return error if valid descriptor not found */
+    if (req->data.bind_socket.sock < 0)
+      return 0;
+  } else if (message->descriptor >= 0) {
+    SCK_CloseSocket(message->descriptor);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ======================================================================= */
+
+/* HELPER - perform adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+static void
+do_adjust_time(const ReqAdjustTime *req, PrvResponse *res)
+{
+  res->rc = adjtime(&req->tv, &res->data.adjust_time.tv);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+static void
+do_adjust_timex(const ReqAdjustTimex *req, PrvResponse *res)
+{
+  res->data.adjust_timex.tmx = req->tmx;
+  res->rc = ntp_adjtime(&res->data.adjust_timex.tmx);
+  if (res->rc < 0)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+static void
+do_set_time(const ReqSetTime *req, PrvResponse *res)
+{
+  res->rc = settimeofday(&req->tv, NULL);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+static void
+do_bind_socket(ReqBindSocket *req, PrvResponse *res)
+{
+  IPSockAddr ip_saddr;
+  int sock_fd;
+  struct sockaddr *sa;
+  socklen_t sa_len;
+
+  sa = &req->sa.u;
+  sa_len = req->sa_len;
+  sock_fd = req->sock;
+
+  SCK_SockaddrToIPSockAddr(sa, sa_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort()) {
+    SCK_CloseSocket(sock_fd);
+    res_fatal(res, "Invalid port %d", ip_saddr.port);
+    return;
+  }
+
+  res->rc = bind(sock_fd, sa, sa_len);
+  if (res->rc)
+    res->res_errno = errno;
+
+  /* sock is still open on daemon side, but we're done with it in the helper */
+  SCK_CloseSocket(sock_fd);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+static void
+do_name_to_ipaddress(ReqName2IPAddress *req, PrvResponse *res)
+{
+  /* make sure the string is terminated */
+  req->name[sizeof (req->name) - 1] = '\0';
+
+  res->rc = DNS_Name2IPAddress(req->name, res->data.name_to_ipaddress.addresses,
+                               DNS_MAX_ADDRESSES);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Reload() */
+
+#ifdef PRIVOPS_RELOADDNS
+static void
+do_reload_dns(PrvResponse *res)
+{
+  DNS_Reload();
+  res->rc = 0;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - main loop - action requests from the daemon */
+
+static void
+helper_main(int fd)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int quit = 0;
+
+  while (!quit) {
+    if (!receive_from_daemon(fd, &req))
+      /* read error or closed input - we cannot recover - give up */
+      break;
+
+    memset(&res, 0, sizeof (res));
+
+    switch (req.op) {
+#ifdef PRIVOPS_ADJUSTTIME
+      case OP_ADJUSTTIME:
+        do_adjust_time(&req.data.adjust_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_ADJUSTTIMEX
+      case OP_ADJUSTTIMEX:
+        do_adjust_timex(&req.data.adjust_timex, &res);
+        break;
+#endif
+#ifdef PRIVOPS_SETTIME
+      case OP_SETTIME:
+        do_set_time(&req.data.set_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_BINDSOCKET
+      case OP_BINDSOCKET:
+        do_bind_socket(&req.data.bind_socket, &res);
+        break;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+      case OP_NAME2IPADDRESS:
+        do_name_to_ipaddress(&req.data.name_to_ipaddress, &res);
+        break;
+#endif
+#ifdef PRIVOPS_RELOADDNS
+      case OP_RELOADDNS:
+        do_reload_dns(&res);
+        break;
+#endif
+      case OP_QUIT:
+        quit = 1;
+        continue;
+
+      default:
+        res_fatal(&res, "Unexpected operator %d", req.op);
+        break;
+    }
+
+    send_response(fd, &res);
+  }
+
+  SCK_CloseSocket(fd);
+  exit(0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - receive helper response */
+
+static void
+receive_response(PrvResponse *res)
+{
+  int resp_len;
+
+  resp_len = SCK_Receive(helper_fd, res, sizeof (*res), 0);
+  if (resp_len < 0)
+    LOG_FATAL("Could not read from helper : %s", strerror(errno));
+  if (resp_len != sizeof (*res))
+    LOG_FATAL("Invalid helper response");
+
+  if (res->fatal_error)
+    LOG_FATAL("Error in helper : %s", res->data.fatal_msg.msg);
+
+  DEBUG_LOG("Received response rc=%d", res->rc);
+
+  /* if operation failed in the helper, set errno so daemon can print log message */
+  if (res->res_errno)
+    errno = res->res_errno;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request to the helper */
+
+static void
+send_request(PrvRequest *req)
+{
+  SCK_Message message;
+  int flags;
+
+  SCK_InitMessage(&message, SCK_ADDR_UNSPEC);
+
+  message.data = req;
+  message.length = sizeof (*req);
+  flags = 0;
+
+  if (req->op == OP_BINDSOCKET) {
+    /* send file descriptor as a control message */
+    message.descriptor = req->data.bind_socket.sock;
+    flags |= SCK_FLAG_MSG_DESCRIPTOR;
+  }
+
+  if (!SCK_SendMessage(helper_fd, &message, flags)) {
+    /* don't try to send another request from exit() */
+    helper_fd = -1;
+    LOG_FATAL("Could not send to helper : %s", strerror(errno));
+  }
+
+  DEBUG_LOG("Sent request op=%d", req->op);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request and wait for response */
+
+static void
+submit_request(PrvRequest *req, PrvResponse *res)
+{
+  send_request(req);
+  receive_response(res);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send the helper a request to exit and wait until it exits */
+
+static void
+stop_helper(void)
+{
+  PrvRequest req;
+  int status;
+
+  if (!have_helper())
+    return;
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_QUIT;
+  send_request(&req);
+
+  waitpid(helper_pid, &status, 0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - request adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+int
+PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper() || delta == NULL)
+    /* helper is not running or read adjustment call */
+    return adjtime(delta, olddelta);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIME;
+  req.data.adjust_time.tv = *delta;
+
+  submit_request(&req, &res);
+
+  if (olddelta)
+    *olddelta = res.data.adjust_time.tv;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+int
+PRV_AdjustTimex(struct timex *tmx)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper())
+    return ntp_adjtime(tmx);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIMEX;
+  req.data.adjust_timex.tmx = *tmx;
+
+  submit_request(&req, &res);
+
+  *tmx = res.data.adjust_timex.tmx;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+int
+PRV_SetTime(const struct timeval *tp, const struct timezone *tzp)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  /* only support setting the time */
+  assert(tp != NULL);
+  assert(tzp == NULL);
+
+  if (!have_helper())
+    return settimeofday(tp, NULL);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_SETTIME;
+  req.data.set_time.tv = *tp;
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+int
+PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len)
+{
+  IPSockAddr ip_saddr;
+  PrvRequest req;
+  PrvResponse res;
+
+  SCK_SockaddrToIPSockAddr(address, address_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort())
+    assert(0);
+
+  if (!have_helper())
+    return bind(sock, address, address_len);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_BINDSOCKET;
+  req.data.bind_socket.sock = sock;
+  req.data.bind_socket.sa_len = address_len;
+  assert(address_len <= sizeof (req.data.bind_socket.sa));
+  memcpy(&req.data.bind_socket.sa.u, address, address_len);
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+int
+PRV_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int i;
+
+  if (!have_helper())
+    return DNS_Name2IPAddress(name, ip_addrs, max_addrs);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_NAME2IPADDRESS;
+  if (snprintf(req.data.name_to_ipaddress.name, sizeof (req.data.name_to_ipaddress.name),
+               "%s", name) >= sizeof (req.data.name_to_ipaddress.name)) {
+    return DNS_Failure;
+  }
+
+  submit_request(&req, &res);
+
+  for (i = 0; i < max_addrs && i < DNS_MAX_ADDRESSES; i++)
+    ip_addrs[i] = res.data.name_to_ipaddress.addresses[i];
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request res_init() */
+
+#ifdef PRIVOPS_RELOADDNS
+void
+PRV_ReloadDNS(void)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper()) {
+    DNS_Reload();
+    return;
+  }
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_RELOADDNS;
+
+  submit_request(&req, &res);
+  assert(!res.rc);
+}
+#endif
+
+/* ======================================================================= */
+
+void
+PRV_Initialise(void)
+{
+  helper_fd = -1;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - setup socket(s) then fork to run the helper */
+/* must be called before privileges are dropped */
+
+void
+PRV_StartHelper(void)
+{
+  pid_t pid;
+  int fd, sock_fd1, sock_fd2;
+
+  if (have_helper())
+    LOG_FATAL("Helper already running");
+
+  sock_fd1 = SCK_OpenUnixSocketPair(SCK_FLAG_BLOCK, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");
+
+  pid = fork();
+  if (pid < 0)
+    LOG_FATAL("fork() failed : %s", strerror(errno));
+
+  if (pid == 0) {
+    /* child process */
+    SCK_CloseSocket(sock_fd1);
+
+    /* close other descriptors inherited from the parent process, except
+       stdin, stdout, and stderr */
+    for (fd = STDERR_FILENO + 1; fd < 1024; fd++) {
+      if (fd != sock_fd2)
+        close(fd);
+    }
+
+    UTI_ResetGetRandomFunctions();
+
+    /* ignore signals, the process will exit on OP_QUIT request */
+    UTI_SetQuitSignalsHandler(SIG_IGN, 1);
+
+    helper_main(sock_fd2);
+
+  } else {
+    /* parent process */
+    SCK_CloseSocket(sock_fd2);
+    helper_fd = sock_fd1;
+    helper_pid = pid;
+
+    /* stop the helper even when not exiting cleanly from the main function */
+    atexit(stop_helper);
+  }
+}
+
+/* ======================================================================= */
+
+/* DAEMON - graceful shutdown of the helper */
+
+void
+PRV_Finalise(void)
+{
+  if (!have_helper())
+    return;
+
+  stop_helper();
+  close(helper_fd);
+  helper_fd = -1;
+}
diff --git a/privops.h b/privops.h
new file mode 100644
index 0000000..146580b
--- /dev/null
+++ b/privops.h
@@ -0,0 +1,77 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+
+*/
+
+#ifndef GOT_PRIVOPS_H
+#define GOT_PRIVOPS_H
+
+#ifdef PRIVOPS_ADJUSTTIME
+int PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta);
+#else
+#define PRV_AdjustTime adjtime
+#endif
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+int PRV_AdjustTimex(struct timex *txc);
+#else
+#define PRV_AdjustTimex ntp_adjtime
+#endif
+
+#ifdef PRIVOPS_SETTIME
+int PRV_SetTime(const struct timeval *tp, const struct timezone *tzp);
+#else
+#define PRV_SetTime settimeofday
+#endif
+
+#ifdef PRIVOPS_BINDSOCKET
+int PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len);
+#else
+#define PRV_BindSocket bind
+#endif
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+int PRV_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs);
+#else
+#define PRV_Name2IPAddress DNS_Name2IPAddress
+#endif
+
+#ifdef PRIVOPS_RELOADDNS
+void PRV_ReloadDNS(void);
+#else
+#define PRV_ReloadDNS DNS_Reload
+#endif
+
+#ifdef PRIVOPS_HELPER
+void PRV_Initialise(void);
+void PRV_StartHelper(void);
+void PRV_Finalise(void);
+#else
+#define PRV_Initialise()
+#define PRV_StartHelper()
+#define PRV_Finalise()
+#endif
+
+#endif
diff --git a/ptp.h b/ptp.h
new file mode 100644
index 0000000..7a93590
--- /dev/null
+++ b/ptp.h
@@ -0,0 +1,64 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the Precision Time Protocol (PTP).
+
+  */
+#ifndef GOT_PTP_H
+#define GOT_PTP_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+
+#define PTP_VERSION 2
+#define PTP_TYPE_DELAY_REQ 1
+#define PTP_DOMAIN_NTP 123
+#define PTP_FLAG_UNICAST (1 << (2 + 8))
+#define PTP_TLV_NTP 0x2023
+
+typedef struct {
+  uint8_t type;
+  uint8_t version;
+  uint16_t length;
+  uint8_t domain;
+  uint8_t min_sdoid;
+  uint16_t flags;
+  uint8_t rest[26];
+} PTP_Header;
+
+typedef struct {
+  uint16_t type;
+  uint16_t length;
+} PTP_TlvHeader;
+
+typedef struct {
+  PTP_Header header;
+  uint8_t origin_ts[10];
+  PTP_TlvHeader tlv_header;
+  NTP_Packet ntp_msg;
+} PTP_NtpMessage;
+
+#define PTP_NTP_PREFIX_LENGTH (int)offsetof(PTP_NtpMessage, ntp_msg)
+
+#endif
diff --git a/quantiles.c b/quantiles.c
new file mode 100644
index 0000000..52953db
--- /dev/null
+++ b/quantiles.c
@@ -0,0 +1,209 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Estimation of quantiles using the Frugal-2U streaming algorithm
+  (https://arxiv.org/pdf/1407.1121v1.pdf)
+  */
+
+#include "config.h"
+
+#include "logging.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "regress.h"
+#include "util.h"
+
+/* Maximum number of repeated estimates for stabilisation */
+#define MAX_REPEAT 64
+
+struct Quantile {
+  double est;
+  double step;
+  int sign;
+};
+
+struct QNT_Instance_Record {
+  struct Quantile *quants;
+  int n_quants;
+  int repeat;
+  int q;
+  int min_k;
+  double min_step;
+  int n_set;
+};
+
+/* ================================================== */
+
+QNT_Instance
+QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step)
+{
+  QNT_Instance inst;
+  long seed;
+
+  if (q < 2 || min_k > max_k || min_k < 1 || max_k >= q ||
+      repeat < 1 || repeat > MAX_REPEAT || min_step <= 0.0)
+    assert(0);
+
+  inst = MallocNew(struct QNT_Instance_Record);
+  inst->n_quants = (max_k - min_k + 1) * repeat;
+  inst->quants = MallocArray(struct Quantile, inst->n_quants);
+  inst->repeat = repeat;
+  inst->q = q;
+  inst->min_k = min_k;
+  inst->min_step = min_step;
+
+  QNT_Reset(inst);
+
+  /* Seed the random number generator, which will not be isolated from
+     other instances and other random() users */
+  UTI_GetRandomBytes(&seed, sizeof (seed));
+  srandom(seed);
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+QNT_DestroyInstance(QNT_Instance inst)
+{
+  Free(inst->quants);
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+QNT_Reset(QNT_Instance inst)
+{
+  int i;
+
+  inst->n_set = 0;
+
+  for (i = 0; i < inst->n_quants; i++) {
+    inst->quants[i].est = 0.0;
+    inst->quants[i].step = inst->min_step;
+    inst->quants[i].sign = 1;
+  }
+}
+
+/* ================================================== */
+
+static void
+insert_initial_value(QNT_Instance inst, double value)
+{
+  int i, j, r = inst->repeat;
+
+  if (inst->n_set * r >= inst->n_quants)
+    assert(0);
+
+  /* Keep the initial estimates repeated and ordered */
+  for (i = inst->n_set; i > 0 && inst->quants[(i - 1) * r].est > value; i--) {
+    for (j = 0; j < r; j++)
+      inst->quants[i * r + j].est = inst->quants[(i - 1) * r].est;
+  }
+
+  for (j = 0; j < r; j++)
+    inst->quants[i * r + j].est = value;
+  inst->n_set++;
+
+  /* Duplicate the largest value in unset quantiles */
+  for (i = inst->n_set * r; i < inst->n_quants; i++)
+    inst->quants[i].est = inst->quants[i - 1].est;
+}
+
+/* ================================================== */
+
+static void
+update_estimate(struct Quantile *quantile, double value, double p, double rand,
+                double min_step)
+{
+  if (value > quantile->est && rand > (1.0 - p)) {
+    quantile->step += quantile->sign > 0 ? min_step : -min_step;
+    quantile->est += quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est > value) {
+      quantile->step += value - quantile->est;
+      quantile->est = value;
+    }
+    if (quantile->sign < 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = 1;
+  } else if (value < quantile->est && rand > p) {
+    quantile->step += quantile->sign < 0 ? min_step : -min_step;
+    quantile->est -= quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est < value) {
+      quantile->step += quantile->est - value;
+      quantile->est = value;
+    }
+    if (quantile->sign > 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = -1;
+  }
+}
+
+/* ================================================== */
+
+void
+QNT_Accumulate(QNT_Instance inst, double value)
+{
+  double p, rand;
+  int i;
+
+  /* Initialise the estimates with first received values */
+  if (inst->n_set * inst->repeat < inst->n_quants) {
+    insert_initial_value(inst, value);
+    return;
+  }
+
+  for (i = 0; i < inst->n_quants; i++) {
+    p = (double)(i / inst->repeat + inst->min_k) / inst->q;
+    rand = (double)random() / ((1U << 31) - 1);
+
+    update_estimate(&inst->quants[i], value, p, rand, inst->min_step);
+  }
+}
+
+/* ================================================== */
+
+int
+QNT_GetMinK(QNT_Instance inst)
+{
+  return inst->min_k;
+}
+
+/* ================================================== */
+
+double
+QNT_GetQuantile(QNT_Instance inst, int k)
+{
+  double estimates[MAX_REPEAT];
+  int i;
+
+  if (k < inst->min_k || k - inst->min_k >= inst->n_quants)
+    assert(0);
+
+  for (i = 0; i < inst->repeat; i++)
+    estimates[i] = inst->quants[(k - inst->min_k) * inst->repeat + i].est;
+
+  return RGR_FindMedian(estimates, inst->repeat);
+}
diff --git a/quantiles.h b/quantiles.h
new file mode 100644
index 0000000..1788544
--- /dev/null
+++ b/quantiles.h
@@ -0,0 +1,41 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for estimation of quantiles.
+
+  */
+
+#ifndef GOT_QUANTILES_H
+#define GOT_QUANTILES_H
+
+typedef struct QNT_Instance_Record *QNT_Instance;
+
+extern QNT_Instance QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step);
+extern void QNT_DestroyInstance(QNT_Instance inst);
+
+extern void QNT_Reset(QNT_Instance inst);
+extern void QNT_Accumulate(QNT_Instance inst, double value);
+extern int QNT_GetMinK(QNT_Instance inst);
+extern double QNT_GetQuantile(QNT_Instance inst, int k);
+
+#endif
diff --git a/refclock.c b/refclock.c
new file mode 100644
index 0000000..84f7439
--- /dev/null
+++ b/refclock.c
@@ -0,0 +1,862 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009-2011, 2013-2014, 2016-2019, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing reference clocks.
+
+  */
+
+#include "config.h"
+
+#include "array.h"
+#include "refclock.h"
+#include "reference.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "util.h"
+#include "sources.h"
+#include "logging.h"
+#include "regress.h"
+#include "samplefilt.h"
+#include "sched.h"
+
+/* Maximum offset of locked reference as a fraction of the PPS interval */
+#define PPS_LOCK_LIMIT 0.4
+
+/* list of refclock drivers */
+extern RefclockDriver RCL_SHM_driver;
+extern RefclockDriver RCL_SOCK_driver;
+extern RefclockDriver RCL_PPS_driver;
+extern RefclockDriver RCL_PHC_driver;
+
+struct FilterSample {
+  double offset;
+  double dispersion;
+  struct timespec sample_time;
+};
+
+struct RCL_Instance_Record {
+  RefclockDriver *driver;
+  void *data;
+  char *driver_parameter;
+  int driver_parameter_length;
+  int driver_poll;
+  int driver_polled;
+  int poll;
+  int leap_status;
+  int local;
+  int pps_forced;
+  int pps_rate;
+  int pps_active;
+  int max_lock_age;
+  int stratum;
+  int tai;
+  uint32_t ref_id;
+  uint32_t lock_ref;
+  double offset;
+  double delay;
+  double precision;
+  double pulse_width;
+  SPF_Instance filter;
+  SCH_TimeoutID timeout_id;
+  SRC_Instance source;
+};
+
+/* Array of pointers to RCL_Instance_Record */
+static ARR_Instance refclocks;
+
+static LOG_FileID logfileid;
+
+static int valid_sample_time(RCL_Instance instance, struct timespec *sample_time);
+static int pps_stratum(RCL_Instance instance, struct timespec *ts);
+static void poll_timeout(void *arg);
+static void slew_samples(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything);
+static void add_dispersion(double dispersion, void *anything);
+static void log_sample(RCL_Instance instance, struct timespec *sample_time, int filtered, int pulse, double raw_offset, double cooked_offset, double dispersion);
+
+static RCL_Instance
+get_refclock(unsigned int index)
+{
+  return *(RCL_Instance *)ARR_GetElement(refclocks, index);
+}
+
+void
+RCL_Initialise(void)
+{
+  refclocks = ARR_CreateInstance(sizeof (RCL_Instance));
+
+  CNF_AddRefclocks();
+
+  if (ARR_GetSize(refclocks) > 0) {
+    LCL_AddParameterChangeHandler(slew_samples, NULL);
+    LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
+  }
+
+  logfileid = CNF_GetLogRefclocks() ? LOG_FileOpen("refclocks",
+      "   Date (UTC) Time         Refid  DP L P  Raw offset   Cooked offset      Disp.")
+    : -1;
+}
+
+void
+RCL_Finalise(void)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    RCL_Instance inst = get_refclock(i);
+
+    if (inst->driver->fini)
+      inst->driver->fini(inst);
+
+    SPF_DestroyInstance(inst->filter);
+    Free(inst->driver_parameter);
+    SRC_DestroyInstance(inst->source);
+    Free(inst);
+  }
+
+  if (ARR_GetSize(refclocks) > 0) {
+    LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+    LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
+  }
+
+  ARR_DestroyInstance(refclocks);
+}
+
+int
+RCL_AddRefclock(RefclockParameters *params)
+{
+  RCL_Instance inst;
+
+  inst = MallocNew(struct RCL_Instance_Record);
+  *(RCL_Instance *)ARR_GetNewElement(refclocks) = inst;
+
+  if (strcmp(params->driver_name, "SHM") == 0) {
+    inst->driver = &RCL_SHM_driver;
+  } else if (strcmp(params->driver_name, "SOCK") == 0) {
+    inst->driver = &RCL_SOCK_driver;
+  } else if (strcmp(params->driver_name, "PPS") == 0) {
+    inst->driver = &RCL_PPS_driver;
+  } else if (strcmp(params->driver_name, "PHC") == 0) {
+    inst->driver = &RCL_PHC_driver;
+  } else {
+    LOG_FATAL("unknown refclock driver %s", params->driver_name);
+  }
+
+  if (!inst->driver->init && !inst->driver->poll)
+    LOG_FATAL("refclock driver %s is not compiled in", params->driver_name);
+
+  if (params->tai && !CNF_GetLeapSecTimezone())
+    LOG_FATAL("refclock tai option requires leapsectz");
+
+  inst->data = NULL;
+  inst->driver_parameter = Strdup(params->driver_parameter);
+  inst->driver_parameter_length = 0;
+  inst->driver_poll = params->driver_poll;
+  inst->poll = params->poll;
+  inst->driver_polled = 0;
+  inst->leap_status = LEAP_Normal;
+  inst->local = params->local;
+  inst->pps_forced = params->pps_forced;
+  inst->pps_rate = params->pps_rate;
+  inst->pps_active = 0;
+  inst->max_lock_age = params->max_lock_age;
+  inst->stratum = params->stratum;
+  inst->tai = params->tai;
+  inst->lock_ref = params->lock_ref_id;
+  inst->offset = params->offset;
+  inst->delay = params->delay;
+  inst->precision = LCL_GetSysPrecisionAsQuantum();
+  inst->precision = MAX(inst->precision, params->precision);
+  inst->pulse_width = params->pulse_width;
+  inst->timeout_id = -1;
+  inst->source = NULL;
+
+  if (inst->driver_parameter) {
+    int i;
+
+    inst->driver_parameter_length = strlen(inst->driver_parameter);
+    for (i = 0; i < inst->driver_parameter_length; i++)
+      if (inst->driver_parameter[i] == ':')
+        inst->driver_parameter[i] = '\0';
+  }
+
+  if (inst->pps_rate < 1)
+    inst->pps_rate = 1;
+
+  if (params->ref_id)
+    inst->ref_id = params->ref_id;
+  else {
+    unsigned char ref[5] = { 0, 0, 0, 0, 0 };
+    unsigned int index = ARR_GetSize(refclocks) - 1;
+
+    snprintf((char *)ref, sizeof (ref), "%3.3s", params->driver_name);
+    ref[3] = index % 10 + '0';
+    if (index >= 10)
+      ref[2] = (index / 10) % 10 + '0';
+
+    inst->ref_id = (uint32_t)ref[0] << 24 | ref[1] << 16 | ref[2] << 8 | ref[3];
+  }
+
+  if (inst->local) {
+    inst->pps_forced = 1;
+    inst->lock_ref = inst->ref_id;
+    inst->leap_status = LEAP_Unsynchronised;
+    inst->max_lock_age = MAX(inst->max_lock_age, 3);
+  }
+
+  if (inst->driver->poll) {
+    int max_samples;
+
+    if (inst->driver_poll > inst->poll)
+      inst->driver_poll = inst->poll;
+
+    max_samples = 1 << (inst->poll - inst->driver_poll);
+    if (max_samples < params->filter_length) {
+      if (max_samples < 4) {
+        LOG(LOGS_WARN, "Setting filter length for %s to %d",
+            UTI_RefidToString(inst->ref_id), max_samples);
+      }
+      params->filter_length = max_samples;
+    }
+  }
+
+  if (inst->driver->init && !inst->driver->init(inst))
+    LOG_FATAL("refclock %s initialisation failed", params->driver_name);
+
+  /* Require the filter to have at least 4 samples to produce a filtered
+     sample, or be full for shorter lengths, and combine 60% of samples
+     closest to the median */
+  inst->filter = SPF_CreateInstance(MIN(params->filter_length, 4), params->filter_length,
+                                    params->max_dispersion, 0.6);
+
+  inst->source = SRC_CreateNewInstance(inst->ref_id, SRC_REFCLOCK, 0, params->sel_options,
+                                       NULL, params->min_samples, params->max_samples,
+                                       0.0, 0.0);
+
+  DEBUG_LOG("refclock %s refid=%s poll=%d dpoll=%d filter=%d",
+      params->driver_name, UTI_RefidToString(inst->ref_id),
+      inst->poll, inst->driver_poll, params->filter_length);
+
+  return 1;
+}
+
+void
+RCL_StartRefclocks(void)
+{
+  unsigned int i, j, n, lock_index;
+
+  n = ARR_GetSize(refclocks);
+
+  for (i = 0; i < n; i++) {
+    RCL_Instance inst = get_refclock(i);
+
+    SRC_SetActive(inst->source);
+    inst->timeout_id = SCH_AddTimeoutByDelay(0.0, poll_timeout, (void *)inst);
+
+    /* Replace lock refid with the refclock's index, or -1 if not valid */
+
+    lock_index = -1;
+
+    if (inst->lock_ref != 0) {
+      for (j = 0; j < n; j++) {
+        RCL_Instance inst2 = get_refclock(j);
+
+        if (inst->lock_ref != inst2->ref_id)
+          continue;
+
+        if (inst->driver->poll && inst2->driver->poll &&
+            (double)inst->max_lock_age / inst->pps_rate < UTI_Log2ToDouble(inst2->driver_poll))
+          LOG(LOGS_WARN, "%s maxlockage too small for %s",
+              UTI_RefidToString(inst->ref_id), UTI_RefidToString(inst2->ref_id));
+
+        lock_index = j;
+        break;
+      }
+
+      if (lock_index == -1 || (lock_index == i && !inst->local))
+        LOG(LOGS_WARN, "Invalid lock refid %s", UTI_RefidToString(inst->lock_ref));
+    }
+
+    inst->lock_ref = lock_index;
+  }
+}
+
+void
+RCL_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  unsigned int i;
+  uint32_t ref_id;
+
+  assert(report->ip_addr.family == IPADDR_INET4);
+  ref_id = report->ip_addr.addr.in4;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    RCL_Instance inst = get_refclock(i);
+    if (inst->ref_id == ref_id) {
+      report->poll = inst->poll;
+      report->mode = RPT_LOCAL_REFERENCE;
+      break;
+    }
+  }
+}
+
+void
+RCL_SetDriverData(RCL_Instance instance, void *data)
+{
+  instance->data = data;
+}
+
+void *
+RCL_GetDriverData(RCL_Instance instance)
+{
+  return instance->data;
+}
+
+char *
+RCL_GetDriverParameter(RCL_Instance instance)
+{
+  return instance->driver_parameter;
+}
+
+static char *
+get_next_driver_option(RCL_Instance instance, char *option)
+{
+  if (option == NULL)
+    option = instance->driver_parameter;
+
+  option += strlen(option) + 1;
+
+  if (option >= instance->driver_parameter + instance->driver_parameter_length)
+    return NULL;
+
+  return option;
+}
+
+void
+RCL_CheckDriverOptions(RCL_Instance instance, const char **options)
+{
+  char *option;
+  int i, len;
+
+  for (option = get_next_driver_option(instance, NULL);
+       option;
+       option = get_next_driver_option(instance, option)) {
+    for (i = 0; options && options[i]; i++) {
+      len = strlen(options[i]);
+      if (!strncmp(options[i], option, len) &&
+          (option[len] == '=' || option[len] == '\0'))
+        break;
+    }
+
+    if (!options || !options[i])
+      LOG_FATAL("Invalid refclock driver option %s", option);
+  }
+}
+
+char *
+RCL_GetDriverOption(RCL_Instance instance, char *name)
+{
+  char *option;
+  int len;
+
+  len = strlen(name);
+
+  for (option = get_next_driver_option(instance, NULL);
+       option;
+       option = get_next_driver_option(instance, option)) {
+    if (!strncmp(name, option, len)) {
+      if (option[len] == '=')
+        return option + len + 1;
+      if (option[len] == '\0')
+        return option + len;
+    }
+  }
+
+  return NULL;
+}
+
+static int
+convert_tai_offset(struct timespec *sample_time, double *offset)
+{
+  struct timespec tai_ts, utc_ts;
+  int tai_offset;
+
+  /* Get approximate TAI-UTC offset for the reference time in TAI */
+  UTI_AddDoubleToTimespec(sample_time, *offset, &tai_ts);
+  tai_offset = REF_GetTaiOffset(&tai_ts);
+
+  /* Get TAI-UTC offset for the reference time in UTC +/- 1 second */
+  UTI_AddDoubleToTimespec(&tai_ts, -tai_offset, &utc_ts);
+  tai_offset = REF_GetTaiOffset(&utc_ts);
+
+  if (!tai_offset)
+    return 0;
+
+  *offset -= tai_offset;
+
+  return 1;
+}
+
+static int
+accumulate_sample(RCL_Instance instance, struct timespec *sample_time, double offset, double dispersion)
+{
+  NTP_Sample sample;
+
+  sample.time = *sample_time;
+  sample.offset = offset;
+  sample.peer_delay = instance->delay;
+  sample.root_delay = instance->delay;
+  sample.peer_dispersion = dispersion;
+  sample.root_dispersion = dispersion;
+
+  return SPF_AccumulateSample(instance->filter, &sample);
+}
+
+int
+RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+              struct timespec *ref_time, int leap)
+{
+  double correction, dispersion, raw_offset, offset;
+  struct timespec cooked_time;
+
+  if (instance->pps_forced)
+    return RCL_AddPulse(instance, sample_time,
+                        1.0e-9 * (sample_time->tv_nsec - ref_time->tv_nsec));
+
+  raw_offset = UTI_DiffTimespecsToDouble(ref_time, sample_time);
+
+  LCL_GetOffsetCorrection(sample_time, &correction, &dispersion);
+  UTI_AddDoubleToTimespec(sample_time, correction, &cooked_time);
+  dispersion += instance->precision;
+
+  /* Make sure the timestamp and offset provided by the driver are sane */
+  if (!UTI_IsTimeOffsetSane(sample_time, raw_offset) ||
+      !valid_sample_time(instance, &cooked_time))
+    return 0;
+
+  switch (leap) {
+    case LEAP_Normal:
+    case LEAP_InsertSecond:
+    case LEAP_DeleteSecond:
+      instance->leap_status = leap;
+      break;
+    default:
+      DEBUG_LOG("refclock sample ignored bad leap %d", leap);
+      return 0;
+  }
+
+  /* Calculate offset = raw_offset - correction + instance->offset
+     in parts to avoid loss of precision if there are large differences */
+  offset = ref_time->tv_sec - sample_time->tv_sec -
+           (time_t)correction + (time_t)instance->offset;
+  offset += 1.0e-9 * (ref_time->tv_nsec - sample_time->tv_nsec) -
+            (correction - (time_t)correction) + (instance->offset - (time_t)instance->offset);
+
+  if (instance->tai && !convert_tai_offset(sample_time, &offset)) {
+    DEBUG_LOG("refclock sample ignored unknown TAI offset");
+    return 0;
+  }
+
+  if (!accumulate_sample(instance, &cooked_time, offset, dispersion))
+    return 0;
+
+  instance->pps_active = 0;
+
+  log_sample(instance, &cooked_time, 0, 0, raw_offset, offset, dispersion);
+
+  /* for logging purposes */
+  if (!instance->driver->poll)
+    instance->driver_polled++;
+
+  return 1;
+}
+
+int
+RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second)
+{
+  double correction, dispersion;
+  struct timespec cooked_time;
+
+  LCL_GetOffsetCorrection(pulse_time, &correction, &dispersion);
+  UTI_AddDoubleToTimespec(pulse_time, correction, &cooked_time);
+  second += correction;
+
+  if (!UTI_IsTimeOffsetSane(pulse_time, 0.0))
+    return 0;
+
+  return RCL_AddCookedPulse(instance, &cooked_time, second, dispersion, correction);
+}
+
+static int
+check_pulse_edge(RCL_Instance instance, double offset, double distance)
+{
+  double max_error;
+
+  if (instance->pulse_width <= 0.0)
+    return 1;
+
+  max_error = 1.0 / instance->pps_rate - instance->pulse_width;
+  max_error = MIN(instance->pulse_width, max_error);
+  max_error *= 0.5;
+
+  if (fabs(offset) > max_error || distance > max_error) {
+      DEBUG_LOG("refclock pulse ignored offset=%.9f distance=%.9f max_error=%.9f",
+                offset, distance, max_error);
+      return 0;
+  }
+
+  return 1;
+}
+
+int
+RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
+                   double second, double dispersion, double raw_correction)
+{
+  double offset;
+  int rate;
+  NTP_Leap leap;
+
+  if (!UTI_IsTimeOffsetSane(cooked_time, second) ||
+      !valid_sample_time(instance, cooked_time))
+    return 0;
+
+  leap = LEAP_Normal;
+  dispersion += instance->precision;
+  rate = instance->pps_rate;
+
+  offset = -second + instance->offset;
+
+  /* Adjust the offset to [-0.5/rate, 0.5/rate) interval */
+  offset -= (long)(offset * rate) / (double)rate;
+  if (offset < -0.5 / rate)
+    offset += 1.0 / rate;
+  else if (offset >= 0.5 / rate)
+    offset -= 1.0 / rate;
+
+  if (instance->lock_ref != -1) {
+    RCL_Instance lock_refclock;
+    NTP_Sample ref_sample;
+    double sample_diff, shift;
+
+    lock_refclock = get_refclock(instance->lock_ref);
+
+    if (!SPF_GetLastSample(lock_refclock->filter, &ref_sample)) {
+      if (instance->local) {
+        /* Make the first sample in order to lock to itself */
+        ref_sample.time = *cooked_time;
+        ref_sample.offset = offset;
+        ref_sample.peer_delay = ref_sample.peer_dispersion = 0;
+        ref_sample.root_delay = ref_sample.root_dispersion = 0;
+      } else {
+        DEBUG_LOG("refclock pulse ignored no ref sample");
+        return 0;
+      }
+    }
+
+    ref_sample.root_dispersion += SPF_GetAvgSampleDispersion(lock_refclock->filter);
+
+    sample_diff = UTI_DiffTimespecsToDouble(cooked_time, &ref_sample.time);
+    if (fabs(sample_diff) >= (double)instance->max_lock_age / rate) {
+      DEBUG_LOG("refclock pulse ignored samplediff=%.9f", sample_diff);
+
+      /* Restart the local mode */
+      if (instance->local) {
+        LOG(LOGS_WARN, "Local refclock lost lock");
+        SPF_DropSamples(instance->filter);
+        SRC_ResetInstance(instance->source);
+      }
+      return 0;
+    }
+
+    /* Align the offset to the reference sample */
+    shift = round((ref_sample.offset - offset) * rate) / rate;
+
+    offset += shift;
+
+    if (fabs(ref_sample.offset - offset) +
+        ref_sample.root_dispersion + dispersion > PPS_LOCK_LIMIT / rate) {
+      DEBUG_LOG("refclock pulse ignored offdiff=%.9f refdisp=%.9f disp=%.9f",
+                ref_sample.offset - offset, ref_sample.root_dispersion, dispersion);
+      return 0;
+    }
+
+    if (!check_pulse_edge(instance, ref_sample.offset - offset, 0.0))
+      return 0;
+
+    leap = lock_refclock->leap_status;
+
+    DEBUG_LOG("refclock pulse offset=%.9f offdiff=%.9f samplediff=%.9f",
+              offset, ref_sample.offset - offset, sample_diff);
+  } else {
+    struct timespec ref_time;
+    int is_synchronised, stratum;
+    double root_delay, root_dispersion, distance;
+    uint32_t ref_id;
+
+    /* Ignore the pulse if we are not well synchronized and the local
+       reference is not active */
+
+    REF_GetReferenceParams(cooked_time, &is_synchronised, &leap, &stratum,
+        &ref_id, &ref_time, &root_delay, &root_dispersion);
+    distance = fabs(root_delay) / 2 + root_dispersion;
+
+    if (leap == LEAP_Unsynchronised || distance >= 0.5 / rate) {
+      DEBUG_LOG("refclock pulse ignored offset=%.9f sync=%d dist=%.9f",
+                offset, leap != LEAP_Unsynchronised, distance);
+      /* Drop also all stored samples */
+      SPF_DropSamples(instance->filter);
+      return 0;
+    }
+
+    if (!check_pulse_edge(instance, offset, distance))
+      return 0;
+  }
+
+  if (!accumulate_sample(instance, cooked_time, offset, dispersion))
+    return 0;
+
+  instance->leap_status = leap;
+  instance->pps_active = 1;
+
+  log_sample(instance, cooked_time, 0, 1, offset + raw_correction - instance->offset,
+             offset, dispersion);
+
+  /* for logging purposes */
+  if (!instance->driver->poll)
+    instance->driver_polled++;
+
+  return 1;
+}
+
+double
+RCL_GetPrecision(RCL_Instance instance)
+{
+  return instance->precision;
+}
+
+int
+RCL_GetDriverPoll(RCL_Instance instance)
+{
+  return instance->driver_poll;
+}
+
+static int
+valid_sample_time(RCL_Instance instance, struct timespec *sample_time)
+{
+  struct timespec now;
+  double diff;
+
+  LCL_ReadCookedTime(&now, NULL);
+  diff = UTI_DiffTimespecsToDouble(&now, sample_time);
+
+  if (diff < 0.0 || diff > UTI_Log2ToDouble(instance->poll + 1)) {
+    DEBUG_LOG("%s refclock sample time %s not valid age=%.6f",
+              UTI_RefidToString(instance->ref_id),
+              UTI_TimespecToString(sample_time), diff);
+    return 0;
+  }
+
+  return 1;
+}
+
+static int
+pps_stratum(RCL_Instance instance, struct timespec *ts)
+{
+  struct timespec ref_time;
+  int is_synchronised, stratum;
+  unsigned int i;
+  double root_delay, root_dispersion;
+  NTP_Leap leap;
+  uint32_t ref_id;
+  RCL_Instance refclock;
+
+  REF_GetReferenceParams(ts, &is_synchronised, &leap, &stratum,
+      &ref_id, &ref_time, &root_delay, &root_dispersion);
+
+  /* Don't change our stratum if the local reference is active
+     or this is the current source */
+  if (ref_id == instance->ref_id ||
+      (!is_synchronised && leap != LEAP_Unsynchronised))
+    return stratum - 1;
+
+  /* Or the current source is another PPS refclock */ 
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    refclock = get_refclock(i);
+    if (refclock->ref_id == ref_id &&
+        refclock->pps_active && refclock->lock_ref == -1)
+      return stratum - 1;
+  }
+
+  return 0;
+}
+
+static void
+get_local_stats(RCL_Instance inst, struct timespec *ref, double *freq, double *offset)
+{
+  double offset_sd, freq_sd, skew, root_delay, root_disp;
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+
+  if (SST_Samples(stats) < SST_GetMinSamples(stats)) {
+    UTI_ZeroTimespec(ref);
+    return;
+  }
+
+  SST_GetTrackingData(stats, ref, offset, &offset_sd, freq, &freq_sd,
+                      &skew, &root_delay, &root_disp);
+}
+
+static void
+follow_local(RCL_Instance inst, struct timespec *prev_ref_time, double prev_freq,
+             double prev_offset)
+{
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+  double freq, dfreq, offset, doffset, elapsed;
+  struct timespec now, ref_time;
+
+  get_local_stats(inst, &ref_time, &freq, &offset);
+
+  if (UTI_IsZeroTimespec(prev_ref_time) || UTI_IsZeroTimespec(&ref_time))
+    return;
+
+  dfreq = (freq - prev_freq) / (1.0 - prev_freq);
+  elapsed = UTI_DiffTimespecsToDouble(&ref_time, prev_ref_time);
+  doffset = offset - elapsed * prev_freq - prev_offset;
+
+  if (!REF_AdjustReference(doffset, dfreq))
+    return;
+
+  LCL_ReadCookedTime(&now, NULL);
+  SST_SlewSamples(stats, &now, dfreq, doffset);
+  SPF_SlewSamples(inst->filter, &now, dfreq, doffset);
+
+  /* Keep the offset close to zero to not lose precision */
+  if (fabs(offset) >= 1.0) {
+    SST_CorrectOffset(stats, -round(offset));
+    SPF_CorrectOffset(inst->filter, -round(offset));
+  }
+}
+
+static void
+poll_timeout(void *arg)
+{
+  NTP_Sample sample;
+  int poll, stratum;
+
+  RCL_Instance inst = (RCL_Instance)arg;
+
+  poll = inst->poll;
+
+  if (inst->driver->poll) {
+    poll = inst->driver_poll;
+    inst->driver->poll(inst);
+    inst->driver_polled++;
+  }
+  
+  if (!(inst->driver->poll && inst->driver_polled < (1 << (inst->poll - inst->driver_poll)))) {
+    inst->driver_polled = 0;
+
+    if (SPF_GetFilteredSample(inst->filter, &sample)) {
+      double local_freq, local_offset;
+      struct timespec local_ref_time;
+
+      /* Handle special case when PPS is used with the local reference */
+      if (inst->pps_active && inst->lock_ref == -1)
+        stratum = pps_stratum(inst, &sample.time);
+      else
+        stratum = inst->stratum;
+
+      if (inst->local) {
+        get_local_stats(inst, &local_ref_time, &local_freq, &local_offset);
+        inst->leap_status = LEAP_Unsynchronised;
+      }
+
+      SRC_UpdateReachability(inst->source, 1);
+      SRC_UpdateStatus(inst->source, stratum, inst->leap_status);
+      SRC_AccumulateSample(inst->source, &sample);
+      SRC_SelectSource(inst->source);
+
+      if (inst->local)
+        follow_local(inst, &local_ref_time, local_freq, local_offset);
+
+      log_sample(inst, &sample.time, 1, 0, 0.0, sample.offset, sample.peer_dispersion);
+    } else {
+      SRC_UpdateReachability(inst->source, 0);
+    }
+  }
+
+  inst->timeout_id = SCH_AddTimeoutByDelay(UTI_Log2ToDouble(poll), poll_timeout, arg);
+}
+
+static void
+slew_samples(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    if (change_type == LCL_ChangeUnknownStep)
+      SPF_DropSamples(get_refclock(i)->filter);
+    else
+      SPF_SlewSamples(get_refclock(i)->filter, cooked, dfreq, doffset);
+  }
+}
+
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++)
+    SPF_AddDispersion(get_refclock(i)->filter, dispersion);
+}
+
+static void
+log_sample(RCL_Instance instance, struct timespec *sample_time, int filtered, int pulse, double raw_offset, double cooked_offset, double dispersion)
+{
+  char sync_stats[4] = {'N', '+', '-', '?'};
+
+  if (logfileid == -1)
+    return;
+
+  if (!filtered) {
+    LOG_FileWrite(logfileid, "%s.%06d %-5s %3d %1c %1d %13.6e %13.6e %10.3e",
+      UTI_TimeToLogForm(sample_time->tv_sec),
+      (int)sample_time->tv_nsec / 1000,
+      UTI_RefidToString(instance->ref_id),
+      instance->driver_polled,
+      sync_stats[instance->leap_status],
+      pulse,
+      raw_offset,
+      cooked_offset,
+      dispersion);
+  } else {
+    LOG_FileWrite(logfileid, "%s.%06d %-5s   - %1c -       -       %13.6e %10.3e",
+      UTI_TimeToLogForm(sample_time->tv_sec),
+      (int)sample_time->tv_nsec / 1000,
+      UTI_RefidToString(instance->ref_id),
+      sync_stats[instance->leap_status],
+      cooked_offset,
+      dispersion);
+  }
+}
diff --git a/refclock.h b/refclock.h
new file mode 100644
index 0000000..7947b62
--- /dev/null
+++ b/refclock.h
@@ -0,0 +1,86 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for refclocks.
+
+  */
+
+#ifndef GOT_REFCLOCK_H
+#define GOT_REFCLOCK_H
+
+#include "srcparams.h"
+#include "sources.h"
+
+typedef struct {
+  char *driver_name;
+  char *driver_parameter;
+  int driver_poll;
+  int poll;
+  int filter_length;
+  int local;
+  int pps_forced;
+  int pps_rate;
+  int min_samples;
+  int max_samples;
+  int sel_options;
+  int max_lock_age;
+  int stratum;
+  int tai;
+  uint32_t ref_id;
+  uint32_t lock_ref_id;
+  double offset;
+  double delay;
+  double precision;
+  double max_dispersion;
+  double pulse_width;
+} RefclockParameters;
+
+typedef struct RCL_Instance_Record *RCL_Instance;
+
+typedef struct {
+  int (*init)(RCL_Instance instance);
+  void (*fini)(RCL_Instance instance);
+  int (*poll)(RCL_Instance instance);
+} RefclockDriver;
+
+extern void RCL_Initialise(void);
+extern void RCL_Finalise(void);
+extern int RCL_AddRefclock(RefclockParameters *params);
+extern void RCL_StartRefclocks(void);
+extern void RCL_ReportSource(RPT_SourceReport *report, struct timespec *now);
+
+/* functions used by drivers */
+extern void RCL_SetDriverData(RCL_Instance instance, void *data);
+extern void *RCL_GetDriverData(RCL_Instance instance);
+extern char *RCL_GetDriverParameter(RCL_Instance instance);
+extern void RCL_CheckDriverOptions(RCL_Instance instance, const char **options);
+extern char *RCL_GetDriverOption(RCL_Instance instance, char *name);
+extern int RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+                         struct timespec *ref_time, int leap);
+extern int RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second);
+extern int RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
+                              double second, double dispersion, double raw_correction);
+extern double RCL_GetPrecision(RCL_Instance instance);
+extern int RCL_GetDriverPoll(RCL_Instance instance);
+
+#endif
diff --git a/refclock_phc.c b/refclock_phc.c
new file mode 100644
index 0000000..e0e206e
--- /dev/null
+++ b/refclock_phc.c
@@ -0,0 +1,184 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2013, 2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  PTP hardware clock (PHC) refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "refclock.h"
+
+#ifdef FEAT_PHC
+
+#include "sysincl.h"
+
+#include "refclock.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+#include "sched.h"
+#include "sys_linux.h"
+
+struct phc_instance {
+  int fd;
+  int mode;
+  int nocrossts;
+  int extpps;
+  int pin;
+  int channel;
+  HCL_Instance clock;
+};
+
+static void read_ext_pulse(int sockfd, int event, void *anything);
+
+static int phc_initialise(RCL_Instance instance)
+{
+  const char *options[] = {"nocrossts", "extpps", "pin", "channel", "clear", NULL};
+  struct phc_instance *phc;
+  int phc_fd, rising_edge;
+  char *path, *s;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  path = RCL_GetDriverParameter(instance);
+ 
+  phc_fd = SYS_Linux_OpenPHC(path, 0);
+  if (phc_fd < 0)
+    LOG_FATAL("Could not open PHC");
+
+  phc = MallocNew(struct phc_instance);
+  phc->fd = phc_fd;
+  phc->mode = 0;
+  phc->nocrossts = RCL_GetDriverOption(instance, "nocrossts") ? 1 : 0;
+  phc->extpps = RCL_GetDriverOption(instance, "extpps") ? 1 : 0;
+
+  phc->clock = HCL_CreateInstance(0, 16, UTI_Log2ToDouble(RCL_GetDriverPoll(instance)),
+                                  RCL_GetPrecision(instance));
+
+  if (phc->extpps) {
+    s = RCL_GetDriverOption(instance, "pin");
+    phc->pin = s ? atoi(s) : 0;
+    s = RCL_GetDriverOption(instance, "channel");
+    phc->channel = s ? atoi(s) : 0;
+    rising_edge = RCL_GetDriverOption(instance, "clear") ? 0 : 1;
+
+    if (!SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel,
+                                         rising_edge, !rising_edge, 1))
+      LOG_FATAL("Could not enable external PHC timestamping");
+
+    SCH_AddFileHandler(phc->fd, SCH_FILE_INPUT, read_ext_pulse, instance);
+  } else {
+    phc->pin = phc->channel = 0;
+  }
+
+  RCL_SetDriverData(instance, phc);
+  return 1;
+}
+
+static void phc_finalise(RCL_Instance instance)
+{
+  struct phc_instance *phc;
+
+  phc = (struct phc_instance *)RCL_GetDriverData(instance);
+
+  if (phc->extpps) {
+    SCH_RemoveFileHandler(phc->fd);
+    SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel, 0, 0, 0);
+  }
+
+  HCL_DestroyInstance(phc->clock);
+  close(phc->fd);
+  Free(phc);
+}
+
+static void read_ext_pulse(int fd, int event, void *anything)
+{
+  RCL_Instance instance;
+  struct phc_instance *phc;
+  struct timespec phc_ts, local_ts;
+  double local_err;
+  int channel;
+
+  instance = anything;
+  phc = RCL_GetDriverData(instance);
+
+  if (!SYS_Linux_ReadPHCExtTimestamp(phc->fd, &phc_ts, &channel))
+    return;
+
+  if (channel != phc->channel) {
+    DEBUG_LOG("Unexpected extts channel %d\n", channel);
+    return;
+  }
+
+  if (!HCL_CookTime(phc->clock, &phc_ts, &local_ts, &local_err))
+    return;
+
+  RCL_AddCookedPulse(instance, &local_ts, 1.0e-9 * local_ts.tv_nsec, local_err,
+                     UTI_DiffTimespecsToDouble(&phc_ts, &local_ts));
+}
+
+#define PHC_READINGS 25
+
+static int phc_poll(RCL_Instance instance)
+{
+  struct timespec phc_ts, sys_ts, local_ts, readings[PHC_READINGS][3];
+  struct phc_instance *phc;
+  double phc_err, local_err;
+  int n_readings;
+
+  phc = (struct phc_instance *)RCL_GetDriverData(instance);
+
+  n_readings = SYS_Linux_GetPHCReadings(phc->fd, phc->nocrossts, &phc->mode,
+                                        PHC_READINGS, readings);
+  if (n_readings < 1)
+    return 0;
+
+  if (!HCL_ProcessReadings(phc->clock, n_readings, readings, &phc_ts, &sys_ts, &phc_err))
+    return 0;
+
+  LCL_CookTime(&sys_ts, &local_ts, &local_err);
+  HCL_AccumulateSample(phc->clock, &phc_ts, &local_ts, phc_err + local_err);
+
+  if (phc->extpps)
+    return 0;
+
+  DEBUG_LOG("PHC offset: %+.9f err: %.9f",
+            UTI_DiffTimespecsToDouble(&phc_ts, &sys_ts), phc_err);
+
+  return RCL_AddSample(instance, &sys_ts, &phc_ts, LEAP_Normal);
+}
+
+RefclockDriver RCL_PHC_driver = {
+  phc_initialise,
+  phc_finalise,
+  phc_poll
+};
+
+#else
+
+RefclockDriver RCL_PHC_driver = { NULL, NULL, NULL };
+
+#endif
diff --git a/refclock_pps.c b/refclock_pps.c
new file mode 100644
index 0000000..880c13f
--- /dev/null
+++ b/refclock_pps.c
@@ -0,0 +1,159 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  PPSAPI refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "refclock.h"
+
+#if FEAT_PPS
+
+#if defined(HAVE_SYS_TIMEPPS_H)
+#include <sys/timepps.h>
+#elif defined(HAVE_TIMEPPS_H)
+#include <timepps.h>
+#endif
+
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+
+struct pps_instance {
+  pps_handle_t handle;
+  pps_seq_t last_seq;
+  int edge_clear;
+};
+
+static int pps_initialise(RCL_Instance instance) {
+  const char *options[] = {"clear", NULL};
+  pps_handle_t handle;
+  pps_params_t params;
+  struct pps_instance *pps;
+  int fd, edge_clear, mode;
+  char *path;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  path = RCL_GetDriverParameter(instance);
+  edge_clear = RCL_GetDriverOption(instance, "clear") ? 1 : 0;
+
+  fd = open(path, O_RDWR);
+  if (fd < 0)
+    LOG_FATAL("Could not open %s : %s", path, strerror(errno));
+
+  UTI_FdSetCloexec(fd);
+
+  if (time_pps_create(fd, &handle) < 0)
+    LOG_FATAL("time_pps_create() failed on %s : %s", path, strerror(errno));
+
+  if (time_pps_getcap(handle, &mode) < 0)
+    LOG_FATAL("time_pps_getcap() failed on %s : %s", path, strerror(errno));
+
+  if (time_pps_getparams(handle, &params) < 0)
+    LOG_FATAL("time_pps_getparams() failed on %s : %s", path, strerror(errno));
+
+  if (!edge_clear) {
+    if (!(mode & PPS_CAPTUREASSERT))
+      LOG_FATAL("CAPTUREASSERT not supported on %s", path);
+
+    params.mode |= PPS_CAPTUREASSERT;
+    params.mode &= ~PPS_CAPTURECLEAR;
+  } else {
+    if (!(mode & PPS_CAPTURECLEAR))
+      LOG_FATAL("CAPTURECLEAR not supported on %s", path);
+
+    params.mode |= PPS_CAPTURECLEAR;
+    params.mode &= ~PPS_CAPTUREASSERT;
+  }
+
+  if (time_pps_setparams(handle, &params) < 0)
+    LOG_FATAL("time_pps_setparams() failed on %s : %s", path, strerror(errno));
+
+  pps = MallocNew(struct pps_instance);
+  pps->handle = handle;
+  pps->last_seq = 0;
+  pps->edge_clear = edge_clear;
+
+  RCL_SetDriverData(instance, pps);
+  return 1;
+}
+
+static void pps_finalise(RCL_Instance instance)
+{
+  struct pps_instance *pps; 
+
+  pps = (struct pps_instance *)RCL_GetDriverData(instance);
+  time_pps_destroy(pps->handle);
+  Free(pps);
+}
+
+static int pps_poll(RCL_Instance instance)
+{
+  struct pps_instance *pps; 
+  struct timespec ts;
+  pps_info_t pps_info;
+  pps_seq_t seq;
+
+  pps = (struct pps_instance *)RCL_GetDriverData(instance);
+
+  ts.tv_sec = 0;
+  ts.tv_nsec = 0;
+
+  if (time_pps_fetch(pps->handle, PPS_TSFMT_TSPEC, &pps_info, &ts) < 0) {
+    LOG(LOGS_ERR, "time_pps_fetch() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  if (!pps->edge_clear) {
+    seq = pps_info.assert_sequence;
+    ts = pps_info.assert_timestamp;
+  } else {
+    seq = pps_info.clear_sequence;
+    ts = pps_info.clear_timestamp;
+  }
+
+  if (seq == pps->last_seq || UTI_IsZeroTimespec(&ts)) {
+    DEBUG_LOG("PPS sample ignored seq=%lu ts=%s",
+              (unsigned long)seq, UTI_TimespecToString(&ts));
+    return 0;
+  }
+
+  pps->last_seq = seq;
+
+  return RCL_AddPulse(instance, &ts, 1.0e-9 * ts.tv_nsec);
+}
+
+RefclockDriver RCL_PPS_driver = {
+  pps_initialise,
+  pps_finalise,
+  pps_poll
+};
+
+#else
+
+RefclockDriver RCL_PPS_driver = { NULL, NULL, NULL };
+
+#endif
diff --git a/refclock_shm.c b/refclock_shm.c
new file mode 100644
index 0000000..ee13e87
--- /dev/null
+++ b/refclock_shm.c
@@ -0,0 +1,134 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  SHM refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "refclock.h"
+#include "logging.h"
+#include "util.h"
+
+#define SHMKEY 0x4e545030
+
+struct shmTime {
+  int    mode; /* 0 - if valid set
+                *       use values, 
+                *       clear valid
+                * 1 - if valid set 
+                *       if count before and after read of values is equal,
+                *         use values 
+                *       clear valid
+                */
+  volatile int count;
+  time_t clockTimeStampSec;
+  int    clockTimeStampUSec;
+  time_t receiveTimeStampSec;
+  int    receiveTimeStampUSec;
+  int    leap;
+  int    precision;
+  int    nsamples;
+  volatile int valid;
+  int    clockTimeStampNSec;
+  int    receiveTimeStampNSec;
+  int    dummy[8]; 
+};
+
+static int shm_initialise(RCL_Instance instance) {
+  const char *options[] = {"perm", NULL};
+  int id, param, perm;
+  char *s;
+  struct shmTime *shm;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  param = atoi(RCL_GetDriverParameter(instance));
+  s = RCL_GetDriverOption(instance, "perm");
+  perm = s ? strtol(s, NULL, 8) & 0777 : 0600;
+
+  id = shmget(SHMKEY + param, sizeof (struct shmTime), IPC_CREAT | perm);
+  if (id == -1) {
+    LOG_FATAL("shmget() failed : %s", strerror(errno));
+    return 0;
+  }
+   
+  shm = (struct shmTime *)shmat(id, 0, 0);
+  if ((long)shm == -1) {
+    LOG_FATAL("shmat() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  RCL_SetDriverData(instance, shm);
+  return 1;
+}
+
+static void shm_finalise(RCL_Instance instance)
+{
+  shmdt(RCL_GetDriverData(instance));
+}
+
+static int shm_poll(RCL_Instance instance)
+{
+  struct timespec receive_ts, clock_ts;
+  struct shmTime t, *shm;
+
+  shm = (struct shmTime *)RCL_GetDriverData(instance);
+
+  t = *shm;
+  
+  if ((t.mode == 1 && t.count != shm->count) ||
+    !(t.mode == 0 || t.mode == 1) || !t.valid) {
+    DEBUG_LOG("SHM sample ignored mode=%d count=%d valid=%d",
+        t.mode, t.count, t.valid);
+    return 0;
+  }
+
+  shm->valid = 0;
+
+  receive_ts.tv_sec = t.receiveTimeStampSec;
+  clock_ts.tv_sec = t.clockTimeStampSec;
+
+  if (t.clockTimeStampNSec / 1000 == t.clockTimeStampUSec &&
+      t.receiveTimeStampNSec / 1000 == t.receiveTimeStampUSec) {
+    receive_ts.tv_nsec = t.receiveTimeStampNSec;
+    clock_ts.tv_nsec = t.clockTimeStampNSec;
+  } else {
+    receive_ts.tv_nsec = 1000 * t.receiveTimeStampUSec;
+    clock_ts.tv_nsec = 1000 * t.clockTimeStampUSec;
+  }
+
+  UTI_NormaliseTimespec(&clock_ts);
+  UTI_NormaliseTimespec(&receive_ts);
+
+  return RCL_AddSample(instance, &receive_ts, &clock_ts, t.leap);
+}
+
+RefclockDriver RCL_SHM_driver = {
+  shm_initialise,
+  shm_finalise,
+  shm_poll
+};
diff --git a/refclock_sock.c b/refclock_sock.c
new file mode 100644
index 0000000..f0d91c5
--- /dev/null
+++ b/refclock_sock.c
@@ -0,0 +1,136 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Unix domain socket refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "refclock.h"
+#include "logging.h"
+#include "util.h"
+#include "sched.h"
+#include "socket.h"
+
+#define SOCK_MAGIC 0x534f434b
+
+struct sock_sample {
+  /* Time of the measurement (system time) */
+  struct timeval tv;
+
+  /* Offset between the true time and the system time (in seconds) */
+  double offset;
+
+  /* Non-zero if the sample is from a PPS signal, i.e. another source
+     is needed to obtain seconds */
+  int pulse;
+
+  /* 0 - normal, 1 - insert leap second, 2 - delete leap second */
+  int leap;
+
+  /* Padding, ignored */
+  int _pad;
+
+  /* Protocol identifier (0x534f434b) */
+  int magic;
+};
+
+static void read_sample(int sockfd, int event, void *anything)
+{
+  struct timespec sys_ts, ref_ts;
+  struct sock_sample sample;
+  RCL_Instance instance;
+  int s;
+
+  instance = (RCL_Instance)anything;
+
+  s = recv(sockfd, &sample, sizeof (sample), 0);
+
+  if (s < 0) {
+    DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
+    return;
+  }
+
+  if (s != sizeof (sample)) {
+    DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
+              s, (long)sizeof (sample));
+    return;
+  }
+
+  if (sample.magic != SOCK_MAGIC) {
+    DEBUG_LOG("Unexpected magic number in SOCK sample : %x != %x",
+              (unsigned int)sample.magic, (unsigned int)SOCK_MAGIC);
+    return;
+  }
+
+  UTI_TimevalToTimespec(&sample.tv, &sys_ts);
+  UTI_NormaliseTimespec(&sys_ts);
+
+  if (!UTI_IsTimeOffsetSane(&sys_ts, sample.offset))
+    return;
+
+  UTI_AddDoubleToTimespec(&sys_ts, sample.offset, &ref_ts);
+
+  if (sample.pulse) {
+    RCL_AddPulse(instance, &sys_ts, sample.offset);
+  } else {
+    RCL_AddSample(instance, &sys_ts, &ref_ts, sample.leap);
+  }
+}
+
+static int sock_initialise(RCL_Instance instance)
+{
+  int sockfd;
+  char *path;
+
+  RCL_CheckDriverOptions(instance, NULL);
+
+  path = RCL_GetDriverParameter(instance);
+ 
+  sockfd = SCK_OpenUnixDatagramSocket(NULL, path, 0);
+  if (sockfd < 0)
+    LOG_FATAL("Could not open socket %s", path);
+
+  RCL_SetDriverData(instance, (void *)(long)sockfd);
+  SCH_AddFileHandler(sockfd, SCH_FILE_INPUT, read_sample, instance);
+  return 1;
+}
+
+static void sock_finalise(RCL_Instance instance)
+{
+  int sockfd;
+
+  sockfd = (long)RCL_GetDriverData(instance);
+  SCH_RemoveFileHandler(sockfd);
+  SCK_RemoveSocket(sockfd);
+  SCK_CloseSocket(sockfd);
+}
+
+RefclockDriver RCL_SOCK_driver = {
+  sock_initialise,
+  sock_finalise,
+  NULL
+};
diff --git a/reference.c b/reference.c
new file mode 100644
index 0000000..e6cc547
--- /dev/null
+++ b/reference.c
@@ -0,0 +1,1437 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2018, 2020, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module keeps track of the source which we are claiming to be
+  our reference, for the purposes of generating outgoing NTP packets */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "memory.h"
+#include "reference.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "local.h"
+#include "sched.h"
+
+/* ================================================== */
+
+/* The minimum allowed skew */
+#define MIN_SKEW 1.0e-12
+
+/* The update interval of the reference in the local reference mode */
+#define LOCAL_REF_UPDATE_INTERVAL 64.0
+
+/* Interval between updates of the drift file */
+#define MAX_DRIFTFILE_AGE 3600.0
+
+static int are_we_synchronised;
+static int enable_local_stratum;
+static int local_stratum;
+static int local_orphan;
+static double local_distance;
+static struct timespec local_ref_time;
+static NTP_Leap our_leap_status;
+static int our_leap_sec;
+static int our_tai_offset;
+static int our_stratum;
+static uint32_t our_ref_id;
+static IPAddr our_ref_ip;
+static struct timespec our_ref_time;
+static double our_skew;
+static double our_residual_freq;
+static double our_root_delay;
+static double our_root_dispersion;
+static double our_offset_sd;
+static double our_frequency_sd;
+
+static double max_update_skew;
+
+static double last_offset;
+static double avg2_offset;
+static int avg2_moving;
+
+static double correction_time_ratio;
+
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* Current operating mode */
+static REF_Mode mode;
+
+/* Threshold and update limit for stepping clock */
+static int make_step_limit;
+static double make_step_threshold;
+
+/* Number of updates before offset checking, number of ignored updates
+   before exiting and the maximum allowed offset */
+static int max_offset_delay;
+static int max_offset_ignore;
+static double max_offset;
+
+/* Threshold for logging clock changes to syslog */
+static double log_change_threshold;
+
+/* Flag, threshold and user for sending mail notification on large clock changes */
+static int do_mail_change;
+static double mail_change_threshold;
+static char *mail_change_user;
+
+/* Handler for mode ending */
+static REF_ModeEndHandler mode_end_handler = NULL;
+
+/* Filename of the drift file. */
+static char *drift_file=NULL;
+static double drift_file_age;
+
+static void update_drift_file(double, double);
+
+/* Leap second handling mode */
+static REF_LeapMode leap_mode;
+
+/* Time of UTC midnight of the upcoming or previous leap second */
+static time_t leap_when;
+
+/* Flag indicating the clock was recently corrected for leap second and it may
+   not have correct time yet (missing 23:59:60 in the UTC time scale) */
+static int leap_in_progress;
+
+/* Timer for the leap second handler */
+static SCH_TimeoutID leap_timeout_id;
+
+/* Name of a system timezone containing leap seconds occuring at midnight */
+static char *leap_tzname;
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+
+/* Exponential moving averages of absolute clock frequencies
+   used as a fallback when synchronisation is lost. */
+
+struct fb_drift {
+  double freq;
+  double secs;
+};
+
+static int fb_drift_min;
+static int fb_drift_max;
+
+static struct fb_drift *fb_drifts = NULL;
+static int next_fb_drift;
+static SCH_TimeoutID fb_drift_timeout_id;
+
+/* Monotonic timestamp of the last reference update */
+static double last_ref_update;
+static double last_ref_update_interval;
+
+static double last_ref_adjustment;
+static int ref_adjustments;
+
+/* ================================================== */
+
+static NTP_Leap get_tz_leap(time_t when, int *tai_offset);
+static void update_leap_status(NTP_Leap leap, time_t now, int reset);
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything)
+{
+  double delta;
+  struct timespec now;
+
+  if (!UTI_IsZeroTimespec(&our_ref_time))
+    UTI_AdjustTimespec(&our_ref_time, cooked, &our_ref_time, &delta, dfreq, doffset);
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    last_ref_update = 0.0;
+    REF_SetUnsynchronised();
+  }
+
+  /* When the clock was stepped, check if that doesn't change our leap status
+     and also reset the leap timeout to undo the shift in the scheduler */
+  if (change_type != LCL_ChangeAdjust && our_leap_sec && !leap_in_progress) {
+    LCL_ReadRawTime(&now);
+    update_leap_status(our_leap_status, now.tv_sec, 1);
+  }
+}
+
+/* ================================================== */
+
+void
+REF_Initialise(void)
+{
+  FILE *in;
+  double file_freq_ppm, file_skew_ppm;
+  double our_frequency_ppm;
+  int tai_offset;
+
+  mode = REF_ModeNormal;
+  are_we_synchronised = 0;
+  our_leap_status = LEAP_Unsynchronised;
+  our_leap_sec = 0;
+  our_tai_offset = 0;
+  initialised = 1;
+  our_root_dispersion = 1.0;
+  our_root_delay = 1.0;
+  our_frequency_ppm = 0.0;
+  our_skew = 1.0; /* i.e. rather bad */
+  our_residual_freq = 0.0;
+  our_frequency_sd = 0.0;
+  our_offset_sd = 0.0;
+  drift_file_age = 0.0;
+
+  /* Now see if we can get the drift file opened */
+  drift_file = CNF_GetDriftFile();
+  if (drift_file) {
+    in = UTI_OpenFile(NULL, drift_file, NULL, 'r', 0);
+    if (in) {
+      if (fscanf(in, "%lf%lf", &file_freq_ppm, &file_skew_ppm) == 2) {
+        /* We have read valid data */
+        our_frequency_ppm = file_freq_ppm;
+        our_skew = 1.0e-6 * file_skew_ppm;
+        if (our_skew < MIN_SKEW)
+          our_skew = MIN_SKEW;
+        LOG(LOGS_INFO, "Frequency %.3f +/- %.3f ppm read from %s",
+            file_freq_ppm, file_skew_ppm, drift_file);
+        LCL_SetAbsoluteFrequency(our_frequency_ppm);
+      } else {
+        LOG(LOGS_WARN, "Could not read valid frequency and skew from driftfile %s",
+            drift_file);
+      }
+      fclose(in);
+    }
+  }
+    
+  if (our_frequency_ppm == 0.0) {
+    our_frequency_ppm = LCL_ReadAbsoluteFrequency();
+    if (our_frequency_ppm != 0.0) {
+      LOG(LOGS_INFO, "Initial frequency %.3f ppm", our_frequency_ppm);
+    }
+  }
+
+  logfileid = CNF_GetLogTracking() ? LOG_FileOpen("tracking",
+      "   Date (UTC) Time     IP Address   St   Freq ppm   Skew ppm     Offset L Co  Offset sd Rem. corr. Root delay Root disp. Max. error")
+    : -1;
+
+  max_update_skew = fabs(CNF_GetMaxUpdateSkew()) * 1.0e-6;
+
+  correction_time_ratio = CNF_GetCorrectionTimeRatio();
+
+  enable_local_stratum = CNF_AllowLocalReference(&local_stratum, &local_orphan, &local_distance);
+  UTI_ZeroTimespec(&local_ref_time);
+
+  leap_when = 0;
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+  leap_mode = CNF_GetLeapSecMode();
+  /* Switch to step mode if the system driver doesn't support leap */
+  if (leap_mode == REF_LeapModeSystem && !LCL_CanSystemLeap())
+    leap_mode = REF_LeapModeStep;
+
+  leap_tzname = CNF_GetLeapSecTimezone();
+  if (leap_tzname) {
+    /* Check that the timezone has good data for Jun 30 2012 and Dec 31 2012 */
+    if (get_tz_leap(1341014400, &tai_offset) == LEAP_InsertSecond && tai_offset == 34 &&
+        get_tz_leap(1356912000, &tai_offset) == LEAP_Normal && tai_offset == 35) {
+      LOG(LOGS_INFO, "Using %s timezone to obtain leap second data", leap_tzname);
+    } else {
+      LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring", leap_tzname);
+      leap_tzname = NULL;
+    }
+  }
+
+  CNF_GetMakeStep(&make_step_limit, &make_step_threshold);
+  CNF_GetMaxChange(&max_offset_delay, &max_offset_ignore, &max_offset);
+  CNF_GetMailOnChange(&do_mail_change, &mail_change_threshold, &mail_change_user);
+  log_change_threshold = CNF_GetLogChange();
+
+  CNF_GetFallbackDrifts(&fb_drift_min, &fb_drift_max);
+
+  if (fb_drift_max >= fb_drift_min && fb_drift_min > 0) {
+    fb_drifts = MallocArray(struct fb_drift, fb_drift_max - fb_drift_min + 1);
+    memset(fb_drifts, 0, sizeof (struct fb_drift) * (fb_drift_max - fb_drift_min + 1));
+    next_fb_drift = 0;
+    fb_drift_timeout_id = 0;
+  }
+
+  UTI_ZeroTimespec(&our_ref_time);
+  last_ref_update = 0.0;
+  last_ref_update_interval = 0.0;
+  last_ref_adjustment = 0.0;
+  ref_adjustments = 0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+
+  /* Make first entry in tracking log */
+  REF_SetUnsynchronised();
+}
+
+/* ================================================== */
+
+void
+REF_Finalise(void)
+{
+  update_leap_status(LEAP_Unsynchronised, 0, 0);
+
+  if (drift_file) {
+    update_drift_file(LCL_ReadAbsoluteFrequency(), our_skew);
+  }
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  Free(fb_drifts);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void REF_SetMode(REF_Mode new_mode)
+{
+  mode = new_mode;
+}
+
+/* ================================================== */
+
+REF_Mode
+REF_GetMode(void)
+{
+  return mode;
+}
+
+/* ================================================== */
+
+void
+REF_SetModeEndHandler(REF_ModeEndHandler handler)
+{
+  mode_end_handler = handler;
+}
+
+/* ================================================== */
+
+REF_LeapMode
+REF_GetLeapMode(void)
+{
+  return leap_mode;
+}
+
+/* ================================================== */
+/* Update the drift coefficients to the file. */
+
+static void
+update_drift_file(double freq_ppm, double skew)
+{
+  FILE *out;
+
+  /* Create a temporary file with a '.tmp' extension. */
+  out = UTI_OpenFile(NULL, drift_file, ".tmp", 'w', 0644);
+  if (!out)
+    return;
+
+  /* Write the frequency and skew parameters in ppm */
+  fprintf(out, "%20.6f %20.6f\n", freq_ppm, 1.0e6 * skew);
+  fclose(out);
+
+  /* Rename the temporary file to the correct location */
+  if (!UTI_RenameTempFile(NULL, drift_file, ".tmp", NULL))
+    ;
+}
+
+/* ================================================== */
+
+static void
+update_fb_drifts(double freq_ppm, double update_interval)
+{
+  int i, secs;
+
+  assert(are_we_synchronised);
+
+  if (next_fb_drift > 0) {
+#if 0
+    /* Reset drifts that were used when we were unsynchronised */
+    for (i = 0; i < next_fb_drift - fb_drift_min; i++)
+      fb_drifts[i].secs = 0.0;
+#endif
+    next_fb_drift = 0;
+  }
+
+  SCH_RemoveTimeout(fb_drift_timeout_id);
+  fb_drift_timeout_id = 0;
+
+  if (update_interval < 1.0 || update_interval > last_ref_update_interval * 4.0)
+    return;
+
+  for (i = 0; i < fb_drift_max - fb_drift_min + 1; i++) {
+    secs = 1 << (i + fb_drift_min);
+    if (fb_drifts[i].secs < secs) {
+      /* Calculate average over 2 * secs interval before switching to
+         exponential updating */
+      fb_drifts[i].freq = (fb_drifts[i].freq * fb_drifts[i].secs +
+          update_interval * 0.5 * freq_ppm) / (update_interval * 0.5 + fb_drifts[i].secs);
+      fb_drifts[i].secs += update_interval * 0.5;
+    } else {
+      /* Update exponential moving average. The smoothing factor for update
+         interval equal to secs is about 0.63, for half interval about 0.39,
+         for double interval about 0.86. */
+      fb_drifts[i].freq += (1 - 1.0 / exp(update_interval / secs)) *
+        (freq_ppm - fb_drifts[i].freq);
+    }
+
+    DEBUG_LOG("Fallback drift %d updated: %f ppm %f seconds",
+              i + fb_drift_min, fb_drifts[i].freq, fb_drifts[i].secs);
+  }
+}
+
+/* ================================================== */
+
+static void
+fb_drift_timeout(void *arg)
+{
+  assert(next_fb_drift >= fb_drift_min && next_fb_drift <= fb_drift_max);
+
+  fb_drift_timeout_id = 0;
+
+  DEBUG_LOG("Fallback drift %d active: %f ppm",
+            next_fb_drift, fb_drifts[next_fb_drift - fb_drift_min].freq);
+  LCL_SetAbsoluteFrequency(fb_drifts[next_fb_drift - fb_drift_min].freq);
+  REF_SetUnsynchronised();
+}
+
+/* ================================================== */
+
+static void
+schedule_fb_drift(void)
+{
+  int i, c, secs;
+  double unsynchronised, now;
+
+  if (fb_drift_timeout_id)
+    return; /* already scheduled */
+
+  now = SCH_GetLastEventMonoTime();
+  unsynchronised = now - last_ref_update;
+
+  for (c = secs = 0, i = fb_drift_min; i <= fb_drift_max; i++) {
+    secs = 1 << i;
+
+    if (fb_drifts[i - fb_drift_min].secs < secs)
+      continue;
+
+    if (unsynchronised < secs && i > next_fb_drift)
+      break;
+
+    c = i;
+  }
+
+  if (c > next_fb_drift) {
+    LCL_SetAbsoluteFrequency(fb_drifts[c - fb_drift_min].freq);
+    next_fb_drift = c;
+    DEBUG_LOG("Fallback drift %d set", c);
+  }
+
+  if (i <= fb_drift_max) {
+    next_fb_drift = i;
+    fb_drift_timeout_id = SCH_AddTimeoutByDelay(secs - unsynchronised, fb_drift_timeout, NULL);
+    DEBUG_LOG("Fallback drift %d scheduled", i);
+  }
+}
+
+/* ================================================== */
+
+static void
+end_ref_mode(int result)
+{
+  mode = REF_ModeIgnore;
+
+  /* Dispatch the handler */
+  if (mode_end_handler)
+    (mode_end_handler)(result);
+}
+
+/* ================================================== */
+
+#define BUFLEN 255
+#define S_MAX_USER_LEN "128"
+
+static void
+maybe_log_offset(double offset, time_t now)
+{
+  double abs_offset;
+  FILE *p;
+  char buffer[BUFLEN], host[BUFLEN];
+  struct tm *tm;
+
+  abs_offset = fabs(offset);
+
+  if (abs_offset > log_change_threshold) {
+    LOG(LOGS_WARN, "System clock wrong by %.6f seconds", -offset);
+  }
+
+  if (do_mail_change &&
+      (abs_offset > mail_change_threshold)) {
+    snprintf(buffer, sizeof (buffer), "%s -t", MAIL_PROGRAM);
+    p = popen(buffer, "w");
+    if (p) {
+      if (gethostname(host, sizeof(host)) < 0) {
+        strcpy(host, "<UNKNOWN>");
+      }
+      host[sizeof (host) - 1] = '\0';
+
+      fprintf(p, "To: %s\n", mail_change_user);
+      fprintf(p, "Subject: chronyd reports change to system clock on node [%s]\n", host);
+      fputs("\n", p);
+
+      tm = localtime(&now);
+      if (tm) {
+        strftime(buffer, sizeof (buffer),
+                 "On %A, %d %B %Y\n  with the system clock reading %H:%M:%S (%Z)", tm);
+        fputs(buffer, p);
+      }
+
+      /* If offset < 0 the local clock is slow, so we are applying a
+         positive change to it to bring it into line, hence the
+         negation of 'offset' in the next statement (and earlier) */
+      fprintf(p,
+              "\n\nchronyd started to apply an adjustment of %.3f seconds to it,\n"
+              "  which exceeded the reporting threshold of %.3f seconds\n\n",
+              -offset, mail_change_threshold);
+      pclose(p);
+    } else {
+      LOG(LOGS_ERR, "Could not send mail notification to user %s\n",
+          mail_change_user);
+    }
+  }
+
+}
+
+/* ================================================== */
+
+static int
+is_step_limit_reached(double offset, double offset_correction)
+{
+  if (make_step_limit == 0) {
+    return 0;
+  } else if (make_step_limit > 0) {
+    make_step_limit--;
+  }
+  return fabs(offset - offset_correction) > make_step_threshold;
+}
+
+/* ================================================== */
+
+static int
+is_offset_ok(double offset)
+{
+  if (max_offset_delay < 0)
+    return 1;
+
+  if (max_offset_delay > 0) {
+    max_offset_delay--;
+    return 1;
+  }
+
+  if (fabs(offset) > max_offset) {
+    LOG(LOGS_WARN, 
+        "Adjustment of %.3f seconds exceeds the allowed maximum of %.3f seconds (%s) ",
+        -offset, max_offset, !max_offset_ignore ? "exiting" : "ignored");
+    if (!max_offset_ignore)
+      end_ref_mode(0);
+    else if (max_offset_ignore > 0)
+      max_offset_ignore--;
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+is_leap_second_day(time_t when)
+{
+  struct tm *stm;
+
+  stm = gmtime(&when);
+  if (!stm)
+    return 0;
+
+  /* Allow leap second only on the last day of June and December */
+  return (stm->tm_mon == 5 && stm->tm_mday == 30) ||
+         (stm->tm_mon == 11 && stm->tm_mday == 31);
+}
+
+/* ================================================== */
+
+static NTP_Leap
+get_tz_leap(time_t when, int *tai_offset)
+{
+  static time_t last_tz_leap_check;
+  static NTP_Leap tz_leap;
+  static int tz_tai_offset;
+
+  struct tm stm, *tm;
+  time_t t;
+  char *tz_env, tz_orig[128];
+
+  *tai_offset = tz_tai_offset;
+
+  /* Do this check at most twice a day */
+  when = when / (12 * 3600) * (12 * 3600);
+  if (last_tz_leap_check == when)
+      return tz_leap;
+
+  last_tz_leap_check = when;
+  tz_leap = LEAP_Normal;
+  tz_tai_offset = 0;
+
+  tm = gmtime(&when);
+  if (!tm)
+    return tz_leap;
+
+  stm = *tm;
+
+  /* Temporarily switch to the timezone containing leap seconds */
+  tz_env = getenv("TZ");
+  if (tz_env) {
+    if (strlen(tz_env) >= sizeof (tz_orig))
+      return tz_leap;
+    strcpy(tz_orig, tz_env);
+  }
+  setenv("TZ", leap_tzname, 1);
+  tzset();
+
+  /* Get the TAI-UTC offset, which started at the epoch at 10 seconds */
+  t = mktime(&stm);
+  if (t != -1)
+    tz_tai_offset = t - when + 10;
+
+  /* Set the time to 23:59:60 and see how it overflows in mktime() */
+  stm.tm_sec = 60;
+  stm.tm_min = 59;
+  stm.tm_hour = 23;
+
+  t = mktime(&stm);
+
+  if (tz_env)
+    setenv("TZ", tz_orig, 1);
+  else
+    unsetenv("TZ");
+  tzset();
+
+  if (t == -1)
+    return tz_leap;
+
+  if (stm.tm_sec == 60)
+    tz_leap = LEAP_InsertSecond;
+  else if (stm.tm_sec == 1)
+    tz_leap = LEAP_DeleteSecond;
+
+  *tai_offset = tz_tai_offset;
+
+  return tz_leap;
+}
+
+/* ================================================== */
+
+static void
+leap_end_timeout(void *arg)
+{
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+
+  if (our_tai_offset)
+    our_tai_offset += our_leap_sec;
+  our_leap_sec = 0;
+
+  if (leap_mode == REF_LeapModeSystem)
+    LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
+
+  if (our_leap_status == LEAP_InsertSecond ||
+      our_leap_status == LEAP_DeleteSecond)
+    our_leap_status = LEAP_Normal;
+}
+
+/* ================================================== */
+
+static void
+leap_start_timeout(void *arg)
+{
+  leap_in_progress = 1;
+
+  switch (leap_mode) {
+    case REF_LeapModeSystem:
+      DEBUG_LOG("Waiting for system clock leap second correction");
+      break;
+    case REF_LeapModeSlew:
+      LCL_NotifyLeap(our_leap_sec);
+      LCL_AccumulateOffset(our_leap_sec, 0.0);
+      LOG(LOGS_WARN, "Adjusting system clock for leap second");
+      break;
+    case REF_LeapModeStep:
+      LCL_NotifyLeap(our_leap_sec);
+      LCL_ApplyStepOffset(our_leap_sec);
+      LOG(LOGS_WARN, "System clock was stepped for leap second");
+      break;
+    case REF_LeapModeIgnore:
+      LOG(LOGS_WARN, "Ignoring leap second");
+      break;
+    default:
+      break;
+  }
+
+  /* Wait until the leap second is over with some extra room to be safe */
+  leap_timeout_id = SCH_AddTimeoutByDelay(2.0, leap_end_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+set_leap_timeout(time_t now)
+{
+  struct timespec when;
+
+  /* Stop old timer if there is one */
+  SCH_RemoveTimeout(leap_timeout_id);
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+
+  if (!our_leap_sec)
+    return;
+
+  leap_when = (now / (24 * 3600) + 1) * (24 * 3600);
+
+  /* Insert leap second at 0:00:00 UTC, delete at 23:59:59 UTC.  If the clock
+     will be corrected by the system, timeout slightly sooner to be sure it
+     will happen before the system correction. */
+  when.tv_sec = leap_when;
+  when.tv_nsec = 0;
+  if (our_leap_sec < 0)
+    when.tv_sec--;
+  if (leap_mode == REF_LeapModeSystem) {
+    when.tv_sec--;
+    when.tv_nsec = 500000000;
+  }
+
+  leap_timeout_id = SCH_AddTimeout(&when, leap_start_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+update_leap_status(NTP_Leap leap, time_t now, int reset)
+{
+  NTP_Leap tz_leap;
+  int leap_sec, tai_offset;
+
+  leap_sec = 0;
+  tai_offset = 0;
+
+  if (leap_tzname && now) {
+    tz_leap = get_tz_leap(now, &tai_offset);
+    if (leap == LEAP_Normal)
+      leap = tz_leap;
+  }
+
+  if (leap == LEAP_InsertSecond || leap == LEAP_DeleteSecond) {
+    /* Check that leap second is allowed today */
+
+    if (is_leap_second_day(now)) {
+      if (leap == LEAP_InsertSecond) {
+        leap_sec = 1;
+      } else {
+        leap_sec = -1;
+      }
+    } else {
+      leap = LEAP_Normal;
+    }
+  }
+  
+  if ((leap_sec != our_leap_sec || tai_offset != our_tai_offset)
+      && !REF_IsLeapSecondClose(NULL, 0.0)) {
+    our_leap_sec = leap_sec;
+    our_tai_offset = tai_offset;
+
+    switch (leap_mode) {
+      case REF_LeapModeSystem:
+        LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
+        /* Fall through */
+      case REF_LeapModeSlew:
+      case REF_LeapModeStep:
+      case REF_LeapModeIgnore:
+        set_leap_timeout(now);
+        break;
+      default:
+        assert(0);
+        break;
+    }
+  } else if (reset) {
+    set_leap_timeout(now);
+  }
+
+  our_leap_status = leap;
+}
+
+/* ================================================== */
+
+static double
+get_root_dispersion(struct timespec *ts)
+{
+  if (UTI_IsZeroTimespec(&our_ref_time))
+    return 1.0;
+
+  return our_root_dispersion +
+         fabs(UTI_DiffTimespecsToDouble(ts, &our_ref_time)) *
+         (our_skew + fabs(our_residual_freq) + LCL_GetMaxClockError());
+}
+
+/* ================================================== */
+
+static void
+update_sync_status(struct timespec *now)
+{
+  double elapsed;
+
+  elapsed = fabs(UTI_DiffTimespecsToDouble(now, &our_ref_time));
+
+  LCL_SetSyncStatus(are_we_synchronised,
+                    our_offset_sd + elapsed * our_frequency_sd,
+                    our_root_delay / 2.0 + get_root_dispersion(now));
+}
+
+/* ================================================== */
+
+static void
+write_log(struct timespec *now, int combined_sources, double freq,
+          double offset, double offset_sd, double uncorrected_offset,
+          double orig_root_distance)
+{
+  const char leap_codes[4] = {'N', '+', '-', '?'};
+  double root_dispersion, max_error;
+  static double last_sys_offset = 0.0;
+
+  if (logfileid == -1)
+    return;
+
+  max_error = orig_root_distance + fabs(last_sys_offset);
+  root_dispersion = get_root_dispersion(now);
+  last_sys_offset = offset - uncorrected_offset;
+
+  LOG_FileWrite(logfileid,
+                "%s %-15s %2d %10.3f %10.3f %10.3e %1c %2d %10.3e %10.3e %10.3e %10.3e %10.3e",
+                UTI_TimeToLogForm(now->tv_sec),
+                our_ref_ip.family != IPADDR_UNSPEC ?
+                  UTI_IPToString(&our_ref_ip) : UTI_RefidToString(our_ref_id),
+                our_stratum, freq, 1.0e6 * our_skew, offset,
+                leap_codes[our_leap_status], combined_sources, offset_sd,
+                uncorrected_offset, our_root_delay, root_dispersion, max_error);
+}
+
+/* ================================================== */
+
+static void
+special_mode_sync(int valid, double offset)
+{
+  int step;
+
+  switch (mode) {
+    case REF_ModeInitStepSlew:
+      if (!valid) {
+        LOG(LOGS_WARN, "No suitable source for initstepslew");
+        end_ref_mode(0);
+        break;
+      }
+
+      step = fabs(offset) >= CNF_GetInitStepThreshold();
+
+      LOG(LOGS_INFO, "System's initial offset : %.6f seconds %s of true (%s)",
+          fabs(offset), offset >= 0 ? "fast" : "slow", step ? "step" : "slew");
+
+      if (step)
+        LCL_ApplyStepOffset(offset);
+      else
+        LCL_AccumulateOffset(offset, 0.0);
+
+      end_ref_mode(1);
+
+      break;
+    case REF_ModeUpdateOnce:
+    case REF_ModePrintOnce:
+      if (!valid) {
+        LOG(LOGS_WARN, "No suitable source for synchronisation");
+        end_ref_mode(0);
+        break;
+      }
+
+      step = mode == REF_ModeUpdateOnce;
+
+      LOG(LOGS_INFO, "System clock wrong by %.6f seconds (%s)",
+          -offset, step ? "step" : "ignored");
+
+      if (step)
+        LCL_ApplyStepOffset(offset);
+
+      end_ref_mode(1);
+
+      break;
+    case REF_ModeIgnore:
+      /* Do nothing until the mode is changed */
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+get_clock_estimates(int manual,
+                    double measured_freq, double measured_skew,
+                    double *estimated_freq, double *estimated_skew,
+                    double *residual_freq)
+{
+  double gain, expected_freq, expected_skew, extra_skew;
+
+  /* We assume that the local clock is running according to our previously
+     determined value */
+  expected_freq = 0.0;
+  expected_skew = our_skew;
+
+  /* Set new frequency based on weighted average of the expected and measured
+     skew.  Disable updates that are based on totally unreliable frequency
+     information unless it is a manual reference. */
+  if (manual) {
+    gain = 1.0;
+  } else if (fabs(measured_skew) > max_update_skew) {
+    DEBUG_LOG("Skew %f too large to track", measured_skew);
+    gain = 0.0;
+  } else {
+    gain = 3.0 * SQUARE(expected_skew) /
+           (3.0 * SQUARE(expected_skew) + SQUARE(measured_skew));
+  }
+
+  gain = CLAMP(0.0, gain, 1.0);
+
+  *estimated_freq = expected_freq + gain * (measured_freq - expected_freq);
+  *residual_freq = measured_freq - *estimated_freq;
+
+  extra_skew = sqrt(SQUARE(expected_freq - *estimated_freq) * (1.0 - gain) +
+                    SQUARE(measured_freq - *estimated_freq) * gain);
+
+  *estimated_skew = expected_skew + gain * (measured_skew - expected_skew) + extra_skew;
+}
+
+/* ================================================== */
+
+static void
+fuzz_ref_time(struct timespec *ts)
+{
+  uint32_t rnd;
+
+  /* Add a random value from interval [-1.0, 0.0] */
+  UTI_GetRandomBytes(&rnd, sizeof (rnd));
+  UTI_AddDoubleToTimespec(ts, -(double)rnd / (uint32_t)-1, ts);
+}
+
+/* ================================================== */
+
+static double
+get_correction_rate(double offset_sd, double update_interval)
+{
+  /* We want to correct the offset quickly, but we also want to keep the
+     frequency error caused by the correction itself low.
+
+     Define correction rate as the area of the region bounded by the graph of
+     offset corrected in time.  Set the rate so that the time needed to correct
+     an offset equal to the current sourcestats stddev will be equal to the
+     update interval multiplied by the correction time ratio (assuming linear
+     adjustment).  The offset and the time needed to make the correction are
+     inversely proportional.
+
+     This is only a suggestion and it's up to the system driver how the
+     adjustment will be executed. */
+
+  return correction_time_ratio * 0.5 * offset_sd * update_interval;
+}
+
+/* ================================================== */
+
+void
+REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
+                 uint32_t ref_id, IPAddr *ref_ip, struct timespec *ref_time,
+                 double offset, double offset_sd,
+                 double frequency, double frequency_sd, double skew,
+                 double root_delay, double root_dispersion)
+{
+  double uncorrected_offset, accumulate_offset, step_offset;
+  double residual_frequency, local_abs_frequency;
+  double elapsed, mono_now, update_interval, orig_root_distance;
+  struct timespec now, raw_now;
+  int manual;
+
+  assert(initialised);
+
+  /* Special modes are implemented elsewhere */
+  if (mode != REF_ModeNormal) {
+    special_mode_sync(1, offset);
+    return;
+  }
+
+  manual = leap == LEAP_Unsynchronised;
+
+  mono_now = SCH_GetLastEventMonoTime();
+  LCL_ReadRawTime(&raw_now);
+  LCL_GetOffsetCorrection(&raw_now, &uncorrected_offset, NULL);
+  UTI_AddDoubleToTimespec(&raw_now, uncorrected_offset, &now);
+
+  elapsed = UTI_DiffTimespecsToDouble(&now, ref_time);
+  offset += elapsed * frequency;
+
+  if (last_ref_update != 0.0) {
+    update_interval = mono_now - last_ref_update;
+  } else {
+    update_interval = 0.0;
+  }
+
+  /* Get new estimates of the frequency and skew including the new data */
+  get_clock_estimates(manual, frequency, skew,
+                      &frequency, &skew, &residual_frequency);
+
+  if (!is_offset_ok(offset))
+    return;
+
+  orig_root_distance = our_root_delay / 2.0 + get_root_dispersion(&now);
+
+  are_we_synchronised = leap != LEAP_Unsynchronised;
+  our_stratum = stratum + 1;
+  our_ref_id = ref_id;
+  if (ref_ip)
+    our_ref_ip = *ref_ip;
+  else
+    our_ref_ip.family = IPADDR_UNSPEC;
+  our_ref_time = *ref_time;
+  our_skew = skew;
+  our_residual_freq = residual_frequency;
+  our_root_delay = root_delay;
+  our_root_dispersion = root_dispersion;
+  our_frequency_sd = frequency_sd;
+  our_offset_sd = offset_sd;
+  last_ref_update = mono_now;
+  last_ref_update_interval = update_interval;
+  last_offset = offset;
+
+  /* Check if the clock should be stepped */
+  if (is_step_limit_reached(offset, uncorrected_offset)) {
+    /* Cancel the uncorrected offset and correct the total offset by step */
+    accumulate_offset = uncorrected_offset;
+    step_offset = offset - uncorrected_offset;
+  } else {
+    accumulate_offset = offset;
+    step_offset = 0.0;
+  }
+
+  /* Adjust the clock */
+  LCL_AccumulateFrequencyAndOffset(frequency, accumulate_offset,
+                                   get_correction_rate(offset_sd, update_interval));
+    
+  maybe_log_offset(offset, raw_now.tv_sec);
+
+  if (step_offset != 0.0) {
+    if (LCL_ApplyStepOffset(step_offset))
+      LOG(LOGS_WARN, "System clock was stepped by %.6f seconds", -step_offset);
+  }
+
+  update_leap_status(leap, raw_now.tv_sec, 0);
+  update_sync_status(&now);
+
+  /* Add a random error of up to one second to the reference time to make it
+     less useful when disclosed to NTP and cmdmon clients for estimating
+     receive timestamps in the interleaved symmetric NTP mode */
+  fuzz_ref_time(&our_ref_time);
+
+  local_abs_frequency = LCL_ReadAbsoluteFrequency();
+
+  write_log(&now, combined_sources, local_abs_frequency,
+            offset, offset_sd, uncorrected_offset, orig_root_distance);
+
+  if (drift_file) {
+    /* Update drift file at most once per hour */
+    drift_file_age += update_interval;
+    if (drift_file_age >= MAX_DRIFTFILE_AGE) {
+      update_drift_file(local_abs_frequency, our_skew);
+      drift_file_age = 0.0;
+    }
+  }
+
+  /* Update fallback drifts */
+  if (fb_drifts && are_we_synchronised) {
+    update_fb_drifts(local_abs_frequency, update_interval);
+    schedule_fb_drift();
+  }
+
+  /* Update the moving average of squares of offset, quickly on start */
+  if (avg2_moving) {
+    avg2_offset += 0.1 * (SQUARE(offset) - avg2_offset);
+  } else {
+    if (avg2_offset > 0.0 && avg2_offset < SQUARE(offset))
+      avg2_moving = 1;
+    avg2_offset = SQUARE(offset);
+  }
+
+  ref_adjustments = 0;
+}
+
+/* ================================================== */
+
+int
+REF_AdjustReference(double offset, double frequency)
+{
+  double adj_corr_rate, ref_corr_rate, mono_now;
+
+  mono_now = SCH_GetLastEventMonoTime();
+  ref_adjustments++;
+
+  adj_corr_rate = get_correction_rate(fabs(offset), mono_now - last_ref_adjustment);
+  ref_corr_rate = get_correction_rate(our_offset_sd, last_ref_update_interval) /
+                  ref_adjustments;
+  last_ref_adjustment = mono_now;
+
+  return LCL_AccumulateFrequencyAndOffsetNoHandlers(frequency, offset,
+                                                    MAX(adj_corr_rate, ref_corr_rate));
+}
+
+/* ================================================== */
+
+void
+REF_SetManualReference
+(
+ struct timespec *ref_time,
+ double offset,
+ double frequency,
+ double skew
+)
+{
+  /* We are not synchronised to an external source, as such.  This is
+     only supposed to be used with the local source option, really.
+     Log as MANU in the tracking log, packets will have NTP_REFID_LOCAL. */
+  REF_SetReference(0, LEAP_Unsynchronised, 1, 0x4D414E55UL, NULL,
+                   ref_time, offset, 0.0, frequency, skew, skew, 0.0, 0.0);
+}
+
+/* ================================================== */
+
+void
+REF_SetUnsynchronised(void)
+{
+  /* Variables required for logging to statistics log */
+  struct timespec now, now_raw;
+  double uncorrected_offset;
+
+  assert(initialised);
+
+  /* Special modes are implemented elsewhere */
+  if (mode != REF_ModeNormal) {
+    special_mode_sync(0, 0.0);
+    return;
+  }
+
+  LCL_ReadRawTime(&now_raw);
+  LCL_GetOffsetCorrection(&now_raw, &uncorrected_offset, NULL);
+  UTI_AddDoubleToTimespec(&now_raw, uncorrected_offset, &now);
+
+  if (fb_drifts) {
+    schedule_fb_drift();
+  }
+
+  update_leap_status(LEAP_Unsynchronised, 0, 0);
+  our_ref_ip.family = IPADDR_INET4;
+  our_ref_ip.addr.in4 = 0;
+  our_stratum = 0;
+  are_we_synchronised = 0;
+
+  LCL_SetSyncStatus(0, 0.0, 0.0);
+
+  write_log(&now, 0, LCL_ReadAbsoluteFrequency(), 0.0, 0.0, uncorrected_offset,
+            our_root_delay / 2.0 + get_root_dispersion(&now));
+}
+
+/* ================================================== */
+
+void
+REF_UpdateLeapStatus(NTP_Leap leap)
+{
+  struct timespec raw_now, now;
+
+  /* Wait for a full reference update if not already synchronised */
+  if (!are_we_synchronised)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, &raw_now);
+
+  update_leap_status(leap, raw_now.tv_sec, 0);
+
+  /* Update also the synchronisation status */
+  update_sync_status(&now);
+}
+
+/* ================================================== */
+
+void
+REF_GetReferenceParams
+(
+ struct timespec *local_time,
+ int *is_synchronised,
+ NTP_Leap *leap_status,
+ int *stratum,
+ uint32_t *ref_id,
+ struct timespec *ref_time,
+ double *root_delay,
+ double *root_dispersion
+)
+{
+  double dispersion, delta;
+
+  assert(initialised);
+
+  if (are_we_synchronised) {
+    dispersion = get_root_dispersion(local_time);
+  } else {
+    dispersion = 0.0;
+  }
+
+  /* Local reference is active when enabled and the clock is not synchronised
+     or the root distance exceeds the threshold */
+
+  if (are_we_synchronised &&
+      !(enable_local_stratum && our_root_delay / 2 + dispersion > local_distance)) {
+
+    *is_synchronised = 1;
+
+    *stratum = our_stratum;
+
+    *leap_status = !leap_in_progress ? our_leap_status : LEAP_Unsynchronised;
+    *ref_id = our_ref_id;
+    *ref_time = our_ref_time;
+    *root_delay = our_root_delay;
+    *root_dispersion = dispersion;
+
+  } else if (enable_local_stratum) {
+
+    *is_synchronised = 0;
+
+    *stratum = local_stratum;
+    *ref_id = NTP_REFID_LOCAL;
+
+    /* Keep the reference timestamp up to date.  Adjust the timestamp to make
+       sure that the transmit timestamp cannot come before this (which might
+       fail a test of an NTP client). */
+    delta = UTI_DiffTimespecsToDouble(local_time, &local_ref_time);
+    if (delta > LOCAL_REF_UPDATE_INTERVAL || delta < 1.0) {
+      UTI_AddDoubleToTimespec(local_time, -1.0, &local_ref_time);
+      fuzz_ref_time(&local_ref_time);
+    }
+
+    *ref_time = local_ref_time;
+
+    /* Not much else we can do for leap second bits - maybe need to
+       have a way for the administrator to feed leap bits in */
+    *leap_status = LEAP_Normal;
+    
+    *root_delay = 0.0;
+    *root_dispersion = 0.0;
+    
+  } else {
+
+    *is_synchronised = 0;
+
+    *leap_status = LEAP_Unsynchronised;
+    *stratum = NTP_MAX_STRATUM;
+    *ref_id = NTP_REFID_UNSYNC;
+    UTI_ZeroTimespec(ref_time);
+    /* These values seem to be standard for a client, and
+       any peer or client of ours will ignore them anyway because
+       we don't claim to be synchronised */
+    *root_dispersion = 1.0;
+    *root_delay = 1.0;
+
+  }
+}
+
+/* ================================================== */
+
+int
+REF_GetOurStratum(void)
+{
+  struct timespec now_cooked, ref_time;
+  int synchronised, stratum;
+  NTP_Leap leap_status;
+  uint32_t ref_id;
+  double root_delay, root_dispersion;
+
+  SCH_GetLastEventTime(&now_cooked, NULL, NULL);
+  REF_GetReferenceParams(&now_cooked, &synchronised, &leap_status, &stratum,
+                         &ref_id, &ref_time, &root_delay, &root_dispersion);
+
+  return stratum;
+}
+
+/* ================================================== */
+
+int
+REF_GetOrphanStratum(void)
+{
+  if (!enable_local_stratum || !local_orphan || mode != REF_ModeNormal)
+    return NTP_MAX_STRATUM;
+  return local_stratum;
+}
+
+/* ================================================== */
+
+double
+REF_GetSkew(void)
+{
+  return our_skew;
+}
+
+/* ================================================== */
+
+void
+REF_ModifyMaxupdateskew(double new_max_update_skew)
+{
+  max_update_skew = new_max_update_skew * 1.0e-6;
+}
+
+/* ================================================== */
+
+void
+REF_ModifyMakestep(int limit, double threshold)
+{
+  make_step_limit = limit;
+  make_step_threshold = threshold;
+}
+
+/* ================================================== */
+
+void
+REF_EnableLocal(int stratum, double distance, int orphan)
+{
+  enable_local_stratum = 1;
+  local_stratum = CLAMP(1, stratum, NTP_MAX_STRATUM - 1);
+  local_distance = distance;
+  local_orphan = !!orphan;
+}
+
+/* ================================================== */
+
+void
+REF_DisableLocal(void)
+{
+  enable_local_stratum = 0;
+}
+
+/* ================================================== */
+
+#define LEAP_SECOND_CLOSE 5
+
+static int
+is_leap_close(time_t t)
+{
+  return leap_when != 0 &&
+         t >= leap_when - LEAP_SECOND_CLOSE && t < leap_when + LEAP_SECOND_CLOSE;
+}
+
+/* ================================================== */
+
+int REF_IsLeapSecondClose(struct timespec *ts, double offset)
+{
+  struct timespec now, now_raw;
+
+  SCH_GetLastEventTime(&now, NULL, &now_raw);
+
+  if (is_leap_close(now.tv_sec) || is_leap_close(now_raw.tv_sec))
+    return 1;
+
+  if (ts && (is_leap_close(ts->tv_sec) || is_leap_close(ts->tv_sec + offset)))
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+REF_GetTaiOffset(struct timespec *ts)
+{
+  int tai_offset;
+
+  get_tz_leap(ts->tv_sec, &tai_offset);
+
+  return tai_offset;
+}
+
+/* ================================================== */
+
+void
+REF_GetTrackingReport(RPT_TrackingReport *rep)
+{
+  struct timespec now_raw, now_cooked;
+  double correction;
+  int synchronised;
+
+  LCL_ReadRawTime(&now_raw);
+  LCL_GetOffsetCorrection(&now_raw, &correction, NULL);
+  UTI_AddDoubleToTimespec(&now_raw, correction, &now_cooked);
+
+  REF_GetReferenceParams(&now_cooked, &synchronised,
+                         &rep->leap_status, &rep->stratum,
+                         &rep->ref_id, &rep->ref_time,
+                         &rep->root_delay, &rep->root_dispersion);
+
+  if (rep->stratum == NTP_MAX_STRATUM && !synchronised)
+    rep->stratum = 0;
+
+  rep->ip_addr.family = IPADDR_UNSPEC;
+  rep->current_correction = correction;
+  rep->freq_ppm = LCL_ReadAbsoluteFrequency();
+  rep->resid_freq_ppm = 0.0;
+  rep->skew_ppm = 0.0;
+  rep->last_update_interval = last_ref_update_interval;
+  rep->last_offset = last_offset;
+  rep->rms_offset = sqrt(avg2_offset);
+
+  if (synchronised) {
+    rep->ip_addr = our_ref_ip;
+    rep->resid_freq_ppm = 1.0e6 * our_residual_freq;
+    rep->skew_ppm = 1.0e6 * our_skew;
+  }
+}
diff --git a/reference.h b/reference.h
new file mode 100644
index 0000000..73454d4
--- /dev/null
+++ b/reference.h
@@ -0,0 +1,200 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the module that keeps track of the current
+  reference.
+
+  */
+
+#ifndef GOT_REFERENCE_H
+#define GOT_REFERENCE_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+#include "reports.h"
+
+/* Leap second handling modes */
+typedef enum {
+  REF_LeapModeSystem,
+  REF_LeapModeSlew,
+  REF_LeapModeStep,
+  REF_LeapModeIgnore,
+} REF_LeapMode;
+
+/* Init function */
+extern void REF_Initialise(void);
+
+/* Fini function */
+extern void REF_Finalise(void);
+
+typedef enum {
+  REF_ModeNormal,
+  REF_ModeInitStepSlew,
+  REF_ModeUpdateOnce,
+  REF_ModePrintOnce,
+  REF_ModeIgnore,
+} REF_Mode;
+
+/* Set reference update mode */
+extern void REF_SetMode(REF_Mode mode);
+
+/* Get reference update mode */
+extern REF_Mode REF_GetMode(void);
+
+/* Function type for handlers to be called back when mode ends */
+typedef void (*REF_ModeEndHandler)(int result);
+
+/* Set the handler for being notified of mode ending */
+extern void REF_SetModeEndHandler(REF_ModeEndHandler handler);
+
+/* Get leap second handling mode */
+extern REF_LeapMode REF_GetLeapMode(void);
+
+/* Function which takes a local cooked time and returns the estimated
+   time of the reference.  It also returns the other parameters
+   required for forming the outgoing NTP packet.
+
+   local_time is the cooked local time returned by the LCL module
+
+   is_synchronised indicates whether we are synchronised to anything
+   at the moment.
+
+   leap indicates the current leap status
+
+   stratum is the stratum of this machine, when considered to be sync'd to the
+   reference
+   
+   ref_id is the reference_id of the source
+
+   ref_time is the time at which the we last set the reference source up
+
+   root_delay is the root delay of the sample we are using
+
+   root_dispersion is the root dispersion of the sample we are using, with all the
+   skew etc added on.
+
+   */
+
+extern void REF_GetReferenceParams
+(
+ struct timespec *local_time,
+ int *is_synchronised,
+ NTP_Leap *leap,
+ int *stratum,
+ uint32_t *ref_id,
+ struct timespec *ref_time,
+ double *root_delay,
+ double *root_dispersion
+);
+
+/* Function called by the clock selection process to register a new
+   reference source and its parameters
+
+   stratum is the stratum of the reference
+
+   leap is the leap status read from the source
+
+   ref_id is the reference id of the reference
+
+   ref_time is the time at which the parameters are assumed to be
+   correct, in terms of local time
+
+   frequency is the amount of local clock gain relative to the
+   reference per unit time interval of the local clock
+
+   skew is the maximum estimated frequency error (so we are within
+   [frequency+-skew])
+
+   root_delay is the root delay of the sample we are using
+
+   root_dispersion is the root dispersion of the sample we are using
+
+   */
+
+extern void REF_SetReference
+(
+ int stratum,
+ NTP_Leap leap,
+ int combined_sources,
+ uint32_t ref_id,
+ IPAddr *ref_ip,
+ struct timespec *ref_time,
+ double offset,
+ double offset_sd,
+ double frequency,
+ double frequency_sd,
+ double skew,
+ double root_delay,
+ double root_dispersion
+);
+
+extern void REF_SetManualReference
+(
+ struct timespec *ref_time,
+ double offset,
+ double frequency,
+ double skew
+);
+
+/* Mark the local clock as unsynchronised */
+extern void
+REF_SetUnsynchronised(void);
+
+/* Make a small correction of the clock without updating the reference
+   parameters and calling the clock change handlers */
+extern int REF_AdjustReference(double offset, double frequency);
+
+/* Announce a leap second before the full reference update */
+extern void REF_UpdateLeapStatus(NTP_Leap leap);
+
+/* Return the current stratum of this host or 16 if the host is not
+   synchronised */
+extern int REF_GetOurStratum(void);
+
+/* Return stratum of the local reference if orphan mode is enabled */
+extern int REF_GetOrphanStratum(void);
+
+/* Return the current skew */
+extern double REF_GetSkew(void);
+
+/* Modify the setting for the maximum skew we are prepared to allow updates on (in ppm). */
+extern void REF_ModifyMaxupdateskew(double new_max_update_skew);
+
+/* Modify makestep settings */
+extern void REF_ModifyMakestep(int limit, double threshold);
+
+extern void REF_EnableLocal(int stratum, double distance, int orphan);
+extern void REF_DisableLocal(void);
+
+/* Check if either of the current raw and cooked time, and optionally a
+   provided timestamp with an offset, is close to a leap second */
+extern int REF_IsLeapSecondClose(struct timespec *ts, double offset);
+
+/* Return TAI-UTC offset corresponding to a time in UTC if available */
+extern int REF_GetTaiOffset(struct timespec *ts);
+
+extern void REF_GetTrackingReport(RPT_TrackingReport *rep);
+
+#endif /* GOT_REFERENCE_H */
diff --git a/regress.c b/regress.c
new file mode 100644
index 0000000..e767e2f
--- /dev/null
+++ b/regress.c
@@ -0,0 +1,704 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2016-2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Regression algorithms.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "regress.h"
+#include "logging.h"
+#include "util.h"
+
+#define MAX_POINTS 64
+
+void
+RGR_WeightedRegression
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1                    /* estimated standard deviation of
+                                   slope */
+
+ /* Could add correlation stuff later if required */
+)
+{
+  double P, Q, U, V, W;
+  double diff;
+  double u, ui, aa;
+  int i;
+
+  assert(n >= 3);
+
+  W = U = 0;
+  for (i=0; i<n; i++) {
+    U += x[i]        / w[i];
+    W += 1.0         / w[i];
+  }
+
+  u = U / W;
+
+  /* Calculate statistics from data */
+  P = Q = V = 0.0;
+  for (i=0; i<n; i++) {
+    ui = x[i] - u;
+    P += y[i]        / w[i];
+    Q += y[i] * ui   / w[i];
+    V += ui   * ui   / w[i];
+  }
+
+  *b1 = Q / V;
+  *b0 = (P / W) - (*b1) * u;
+
+  *s2 = 0.0;
+  for (i=0; i<n; i++) {
+    diff = y[i] - *b0 - *b1*x[i];
+    *s2 += diff*diff / w[i];
+  }
+
+  *s2 /= (double)(n-2);
+
+  *sb1 = sqrt(*s2 / V);
+  aa = u * (*sb1);
+  *sb0 = sqrt(*s2 / W + aa * aa);
+
+  *s2 *= (n / W); /* Giving weighted average of variances */
+}
+
+/* ================================================== */
+/* Get the coefficient to multiply the standard deviation by, to get a
+   particular size of confidence interval (assuming a t-distribution) */
+  
+double
+RGR_GetTCoef(int dof)
+{
+  /* Assuming now the 99.95% quantile */
+  static const float coefs[] =
+  { 636.6, 31.6, 12.92, 8.61, 6.869,
+    5.959, 5.408, 5.041, 4.781, 4.587,
+    4.437, 4.318, 4.221, 4.140, 4.073,
+    4.015, 3.965, 3.922, 3.883, 3.850,
+    3.819, 3.792, 3.768, 3.745, 3.725,
+    3.707, 3.690, 3.674, 3.659, 3.646,
+    3.633, 3.622, 3.611, 3.601, 3.591,
+    3.582, 3.574, 3.566, 3.558, 3.551};
+
+  if (dof <= 40) {
+    return coefs[dof-1];
+  } else {
+    return 3.5; /* Until I can be bothered to do something better */
+  }
+}
+
+/* ================================================== */
+/* Get 90% quantile of chi-square distribution */
+
+double
+RGR_GetChi2Coef(int dof)
+{
+  static const float coefs[] = {
+    2.706, 4.605, 6.251, 7.779, 9.236, 10.645, 12.017, 13.362,
+    14.684, 15.987, 17.275, 18.549, 19.812, 21.064, 22.307, 23.542,
+    24.769, 25.989, 27.204, 28.412, 29.615, 30.813, 32.007, 33.196,
+    34.382, 35.563, 36.741, 37.916, 39.087, 40.256, 41.422, 42.585,
+    43.745, 44.903, 46.059, 47.212, 48.363, 49.513, 50.660, 51.805,
+    52.949, 54.090, 55.230, 56.369, 57.505, 58.641, 59.774, 60.907,
+    62.038, 63.167, 64.295, 65.422, 66.548, 67.673, 68.796, 69.919,
+    71.040, 72.160, 73.279, 74.397, 75.514, 76.630, 77.745, 78.860
+  };
+
+  if (dof <= 64) {
+    return coefs[dof-1];
+  } else {
+    return 1.2 * dof; /* Until I can be bothered to do something better */
+  }
+}
+
+/* ================================================== */
+/* Critical value for number of runs of residuals with same sign.
+   5% critical region for now. */
+
+static char critical_runs[] = {
+  0,  0,  0,  0,  0,  0,  0,  0,  2,  3,
+  3,  3,  4,  4,  5,  5,  5,  6,  6,  7,
+  7,  7,  8,  8,  9,  9,  9, 10, 10, 11,
+ 11, 11, 12, 12, 13, 13, 14, 14, 14, 15,
+ 15, 16, 16, 17, 17, 18, 18, 18, 19, 19,
+ 20, 20, 21, 21, 21, 22, 22, 23, 23, 24,
+ 24, 25, 25, 26, 26, 26, 27, 27, 28, 28,
+ 29, 29, 30, 30, 30, 31, 31, 32, 32, 33,
+ 33, 34, 34, 35, 35, 35, 36, 36, 37, 37,
+ 38, 38, 39, 39, 40, 40, 40, 41, 41, 42,
+ 42, 43, 43, 44, 44, 45, 45, 46, 46, 46,
+ 47, 47, 48, 48, 49, 49, 50, 50, 51, 51,
+ 52, 52, 52, 53, 53, 54, 54, 55, 55, 56
+};
+
+/* ================================================== */
+
+static int
+n_runs_from_residuals(double *resid, int n)
+{
+  int nruns;
+  int i;
+  
+  nruns = 1;
+  for (i=1; i<n; i++) {
+    if (((resid[i-1] < 0.0) && (resid[i] < 0.0)) ||
+        ((resid[i-1] > 0.0) && (resid[i] > 0.0))) {
+      /* Nothing to do */
+    } else {
+      nruns++;
+    }
+  }
+  
+  return nruns;
+}
+
+/* ================================================== */
+/* Return a boolean indicating whether we had enough points for
+   regression */
+
+int
+RGR_FindBestRegression 
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+ int m,                         /* number of extra samples in x and y arrays
+                                   (negative index) which can be used to
+                                   extend runs test */
+ int min_samples,               /* minimum number of samples to be kept after
+                                   changing the starting index to pass the runs
+                                   test */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1,                   /* estimated standard deviation of
+                                   slope */
+
+ int *new_start,                /* the new starting index to make the
+                                   residuals pass the two tests */
+ 
+ int *n_runs,                   /* number of runs amongst the residuals */
+
+ int *dof                       /* degrees of freedom in statistics (needed
+                                   to get confidence intervals later) */
+
+)
+{
+  double P, Q, U, V, W; /* total */
+  double resid[MAX_POINTS * REGRESS_RUNS_RATIO];
+  double ss;
+  double a, b, u, ui, aa;
+
+  int start, resid_start, nruns, npoints;
+  int i;
+
+  assert(n <= MAX_POINTS && m >= 0);
+  assert(n * REGRESS_RUNS_RATIO < sizeof (critical_runs) / sizeof (critical_runs[0]));
+
+  if (n < MIN_SAMPLES_FOR_REGRESS) {
+    return 0;
+  }
+
+  start = 0;
+  do {
+
+    W = U = 0;
+    for (i=start; i<n; i++) {
+      U += x[i]        / w[i];
+      W += 1.0         / w[i];
+    }
+
+    u = U / W;
+
+    P = Q = V = 0.0;
+    for (i=start; i<n; i++) {
+      ui = x[i] - u;
+      P += y[i]        / w[i];
+      Q += y[i] * ui   / w[i];
+      V += ui   * ui   / w[i];
+    }
+
+    b = Q / V;
+    a = (P / W) - (b * u);
+
+    /* Get residuals also for the extra samples before start */
+    resid_start = n - (n - start) * REGRESS_RUNS_RATIO;
+    if (resid_start < -m)
+      resid_start = -m;
+
+    for (i=resid_start; i<n; i++) {
+      resid[i - resid_start] = y[i] - a - b*x[i];
+    }
+
+    /* Count number of runs */
+    nruns = n_runs_from_residuals(resid, n - resid_start); 
+
+    if (nruns > critical_runs[n - resid_start] ||
+        n - start <= MIN_SAMPLES_FOR_REGRESS ||
+        n - start <= min_samples) {
+      if (start != resid_start) {
+        /* Ignore extra samples in returned nruns */
+        nruns = n_runs_from_residuals(resid + (start - resid_start), n - start);
+      }
+      break;
+    } else {
+      /* Try dropping one sample at a time until the runs test passes. */
+      ++start;
+    }
+
+  } while (1);
+
+  /* Work out statistics from full dataset */
+  *b1 = b;
+  *b0 = a;
+
+  ss = 0.0;
+  for (i=start; i<n; i++) {
+    ss += resid[i - resid_start]*resid[i - resid_start] / w[i];
+  }
+
+  npoints = n - start;
+  ss /= (double)(npoints - 2);
+  *sb1 = sqrt(ss / V);
+  aa = u * (*sb1);
+  *sb0 = sqrt((ss / W) + (aa * aa));
+  *s2 = ss * (double) npoints / W;
+
+  *new_start = start;
+  *dof = npoints - 2;
+  *n_runs = nruns;
+
+  return 1;
+
+}
+
+/* ================================================== */
+
+#define EXCH(a,b) temp=(a); (a)=(b); (b)=temp
+
+/* ================================================== */
+/* Find the index'th biggest element in the array x of n elements.
+   flags is an array where a 1 indicates that the corresponding entry
+   in x is known to be sorted into its correct position and a 0
+   indicates that the corresponding entry is not sorted.  However, if
+   flags[m] = flags[n] = 1 with m<n, then x[m] must be <= x[n] and for
+   all i with m<i<n, x[m] <= x[i] <= x[n].  In practice, this means
+   flags[] has to be the result of a previous call to this routine
+   with the same array x, and is used to remember which parts of the
+   x[] array we have already sorted.
+
+   The approach used is a cut-down quicksort, where we only bother to
+   keep sorting the partition that contains the index we are after.
+   The approach comes from Numerical Recipes in C (ISBN
+   0-521-43108-5). */
+
+static double
+find_ordered_entry_with_flags(double *x, int n, int index, char *flags)
+{
+  int u, v, l, r;
+  double temp;
+  double piv;
+  int pivind;
+
+  assert(index >= 0);
+
+  /* If this bit of the array is already sorted, simple! */
+  if (flags[index]) {
+    return x[index];
+  }
+  
+  /* Find subrange to look at */
+  u = v = index;
+  while (u > 0 && !flags[u]) u--;
+  if (flags[u]) u++;
+
+  while (v < (n-1) && !flags[v]) v++;
+  if (flags[v]) v--;
+
+  do {
+    if (v - u < 2) {
+      if (x[v] < x[u]) {
+        EXCH(x[v], x[u]);
+      }
+      flags[v] = flags[u] = 1;
+      return x[index];
+    } else { 
+      pivind = (u + v) >> 1;
+      EXCH(x[u], x[pivind]);
+      piv = x[u]; /* New value */
+      l = u + 1;
+      r = v;
+      do {
+        while (l < v && x[l] < piv) l++;
+        while (x[r] > piv) r--;
+        if (r <= l) break;
+        EXCH(x[l], x[r]);
+        l++;
+        r--;
+      } while (1);
+      EXCH(x[u], x[r]);
+      flags[r] = 1; /* Pivot now in correct place */
+      if (index == r) {
+        return x[r];
+      } else if (index < r) {
+        v = r - 1;
+      } else if (index > r) {
+        u = l;
+      }
+    }
+  } while (1);
+}
+
+/* ================================================== */
+
+#if 0
+/* Not used, but this is how it can be done */
+static double
+find_ordered_entry(double *x, int n, int index)
+{
+  char flags[MAX_POINTS];
+
+  memset(flags, 0, n * sizeof (flags[0]));
+  return find_ordered_entry_with_flags(x, n, index, flags);
+}
+#endif
+
+/* ================================================== */
+/* Find the median entry of an array x[] with n elements. */
+
+static double
+find_median(double *x, int n)
+{
+  int k;
+  char flags[MAX_POINTS];
+
+  memset(flags, 0, n * sizeof (flags[0]));
+  k = n>>1;
+  if (n&1) {
+    return find_ordered_entry_with_flags(x, n, k, flags);
+  } else {
+    return 0.5 * (find_ordered_entry_with_flags(x, n, k, flags) +
+                  find_ordered_entry_with_flags(x, n, k-1, flags));
+  }
+}
+
+/* ================================================== */
+
+double
+RGR_FindMedian(double *x, int n)
+{
+  double tmp[MAX_POINTS];
+
+  assert(n > 0 && n <= MAX_POINTS);
+  memcpy(tmp, x, n * sizeof (tmp[0]));
+
+  return find_median(tmp, n);
+}
+
+/* ================================================== */
+/* This function evaluates the equation
+
+   \sum_{i=0}^{n-1} x_i sign(y_i - a - b x_i)
+
+   and chooses the value of a that minimises the absolute value of the
+   result.  (See pp703-704 of Numerical Recipes in C). */
+
+static void
+eval_robust_residual
+(double *x,                     /* The independent points */
+ double *y,                     /* The dependent points */
+ int n,                         /* Number of points */
+ double b,                      /* Slope */
+ double *aa,                    /* Intercept giving smallest absolute
+                                   value for the above equation */
+ double *rr                     /* Corresponding value of equation */
+)
+{
+  int i;
+  double a, res, del;
+  double d[MAX_POINTS];
+
+  for (i=0; i<n; i++) {
+    d[i] = y[i] - b * x[i];
+  }
+  
+  a = find_median(d, n);
+
+  res = 0.0;
+  for (i=0; i<n; i++) {
+    del = y[i] - a - b * x[i];
+    if (del > 0.0) {
+      res += x[i];
+    } else if (del < 0.0) {
+      res -= x[i];
+    }
+  }
+
+  *aa = a;
+  *rr = res;
+}
+
+/* ================================================== */
+/* This routine performs a 'robust' regression, i.e. one which has low
+   susceptibility to outliers amongst the data.  If one thinks of a
+   normal (least squares) linear regression in 2D being analogous to
+   the arithmetic mean in 1D, this algorithm in 2D is roughly
+   analogous to the median in 1D.  This algorithm seems to work quite
+   well until the number of outliers is approximately half the number
+   of data points.
+
+   The return value is a status indicating whether there were enough
+   data points to run the routine or not. */
+
+int
+RGR_FindBestRobustRegression
+(double *x,                     /* The independent axis points */
+ double *y,                     /* The dependent axis points (which
+                                   may contain outliers). */
+ int n,                         /* The number of points */
+ double tol,                    /* The tolerance required in
+                                   determining the value of b1 */
+ double *b0,                    /* The estimated Y-axis intercept */
+ double *b1,                    /* The estimated slope */
+ int *n_runs,                   /* The number of runs of residuals */
+ int *best_start                /* The best starting index */
+)
+{
+  int i;
+  int start;
+  int n_points;
+  double a, b;
+  double P, U, V, W, X;
+  double resid, resids[MAX_POINTS];
+  double blo, bhi, bmid, rlo, rhi, rmid;
+  double s2, sb, incr;
+  double mx, dx, my, dy;
+  int nruns = 0;
+
+  assert(n <= MAX_POINTS);
+
+  if (n < 2) {
+    return 0;
+  } else if (n == 2) {
+    /* Just a straight line fit (we need this for the manual mode) */
+    *b1 = (y[1] - y[0]) / (x[1] - x[0]);
+    *b0 = y[0] - (*b1) * x[0];
+    *n_runs = 0;
+    *best_start = 0;
+    return 1;
+  }
+
+  /* else at least 3 points, apply normal algorithm */
+
+  start = 0;
+
+  /* Loop to strip oldest points that cause the regression residuals
+     to fail the number of runs test */
+  do {
+
+    n_points = n - start;
+
+    /* Use standard least squares regression to get starting estimate */
+
+    P = U = 0.0;
+    for (i=start; i<n; i++) {
+      P += y[i];
+      U += x[i];
+    }
+
+    W = (double) n_points;
+
+    my = P/W;
+    mx = U/W;
+
+    X = V = 0.0;
+    for (i=start; i<n; i++) {
+      dy = y[i] - my;
+      dx = x[i] - mx;
+      X += dy * dx;
+      V += dx * dx;
+    }
+
+    b = X / V;
+    a = my - b*mx;
+
+    s2 = 0.0;
+    for (i=start; i<n; i++) {
+      resid = y[i] - a - b * x[i];
+      s2 += resid * resid;
+    }
+
+    /* Need to expand range of b to get a root in the interval.
+       Estimate standard deviation of b and expand range about b based
+       on that. */
+    sb = sqrt(s2 * W/V);
+    incr = MAX(sb, tol);
+  
+    do {
+      incr *= 2.0;
+
+      /* Give up if the interval is too large */
+      if (incr > 100.0)
+        return 0;
+
+      blo = b - incr;
+      bhi = b + incr;
+
+      /* We don't want 'a' yet */
+      eval_robust_residual(x + start, y + start, n_points, blo, &a, &rlo);
+      eval_robust_residual(x + start, y + start, n_points, bhi, &a, &rhi);
+
+    } while (rlo * rhi >= 0.0); /* fn vals have same sign or one is zero,
+                                   i.e. root not in interval (rlo, rhi). */
+
+    /* OK, so the root for b lies in (blo, bhi). Start bisecting */
+    do {
+      bmid = 0.5 * (blo + bhi);
+      if (!(blo < bmid && bmid < bhi))
+        break;
+      eval_robust_residual(x + start, y + start, n_points, bmid, &a, &rmid);
+      if (rmid == 0.0) {
+        break;
+      } else if (rmid * rlo > 0.0) {
+        blo = bmid;
+        rlo = rmid;
+      } else if (rmid * rhi > 0.0) {
+        bhi = bmid;
+        rhi = rmid;
+      } else {
+        assert(0);
+      }
+    } while (bhi - blo > tol);
+
+    *b0 = a;
+    *b1 = bmid;
+
+    /* Number of runs test, but not if we're already down to the
+       minimum number of points */
+    if (n_points == MIN_SAMPLES_FOR_REGRESS) {
+      break;
+    }
+
+    for (i=start; i<n; i++) {
+      resids[i] = y[i] - a - bmid * x[i];
+    }
+
+    nruns = n_runs_from_residuals(resids + start, n_points);
+
+    if (nruns > critical_runs[n_points]) {
+      break;
+    } else {
+      start++;
+    }
+
+  } while (1);
+
+  *n_runs = nruns;
+  *best_start = start;
+
+  return 1;
+
+}
+
+/* ================================================== */
+/* This routine performs linear regression with two independent variables.
+   It returns non-zero status if there were enough data points and there
+   was a solution. */
+
+int
+RGR_MultipleRegress
+(double *x1,                    /* first independent variable */
+ double *x2,                    /* second independent variable */
+ double *y,                     /* measured data */
+
+ int n,                         /* number of data points */
+
+ /* The results */
+ double *b2                     /* estimated second slope */
+                                /* other values are not needed yet */
+)
+{
+  double Sx1, Sx2, Sx1x1, Sx1x2, Sx2x2, Sx1y, Sx2y, Sy;
+  double U, V, V1, V2, V3;
+  int i;
+
+  if (n < 4)
+    return 0;
+
+  Sx1 = Sx2 = Sx1x1 = Sx1x2 = Sx2x2 = Sx1y = Sx2y = Sy = 0.0;
+
+  for (i = 0; i < n; i++) {
+    Sx1 += x1[i];
+    Sx2 += x2[i];
+    Sx1x1 += x1[i] * x1[i];
+    Sx1x2 += x1[i] * x2[i];
+    Sx2x2 += x2[i] * x2[i];
+    Sx1y += x1[i] * y[i];
+    Sx2y += x2[i] * y[i];
+    Sy += y[i];
+  }
+
+  U = n * (Sx1x2 * Sx1y - Sx1x1 * Sx2y) +
+      Sx1 * Sx1 * Sx2y - Sx1 * Sx2 * Sx1y +
+      Sy * (Sx2 * Sx1x1 - Sx1 * Sx1x2);
+
+  V1 = n * (Sx1x2 * Sx1x2 - Sx1x1 * Sx2x2);
+  V2 = Sx1 * Sx1 * Sx2x2 + Sx2 * Sx2 * Sx1x1;
+  V3 = -2.0 * Sx1 * Sx2 * Sx1x2;
+  V = V1 + V2 + V3;
+
+  /* Check if there is a (numerically stable) solution */
+  if (fabs(V) * 1.0e10 <= -V1 + V2 + fabs(V3))
+    return 0;
+
+  *b2 = U / V;
+
+  return 1;
+}
diff --git a/regress.h b/regress.h
new file mode 100644
index 0000000..90055da
--- /dev/null
+++ b/regress.h
@@ -0,0 +1,137 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for regression routine(s)
+
+  */
+
+#ifndef GOT_REGRESS_H
+#define GOT_REGRESS_H
+
+extern void
+RGR_WeightedRegression
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance (weighted) of
+                                   data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1                    /* estimated standard deviation of
+                                   slope */
+
+ /* Could add correlation stuff later if required */
+);
+
+/* Return the weighting to apply to the standard deviation to get a
+   given size of confidence interval assuming a T distribution */
+
+extern double RGR_GetTCoef(int dof);
+
+/* Return the value to apply to the variance to make an upper one-sided
+   test assuming a chi-square distribution. */
+
+extern double RGR_GetChi2Coef(int dof);
+
+/* Maximum ratio of number of points used for runs test to number of regression
+   points */
+#define REGRESS_RUNS_RATIO 2
+
+/* Minimum number of samples for regression */
+#define MIN_SAMPLES_FOR_REGRESS 3
+
+/* Return a status indicating whether there were enough points to
+   carry out the regression */
+
+extern int
+RGR_FindBestRegression 
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+ int m,                         /* number of extra samples in x and y arrays
+                                   (negative index) which can be used to
+                                   extend runs test */
+ int min_samples,               /* minimum number of samples to be kept after
+                                   changing the starting index to pass the runs
+                                   test */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1,                   /* estimated standard deviation of
+                                   slope */
+
+ int *new_start,                /* the new starting index to make the
+                                   residuals pass the two tests */
+
+ int *n_runs,                   /* number of runs amongst the residuals */
+
+ int *dof                       /* degrees of freedom in statistics (needed
+                                   to get confidence intervals later) */
+
+);
+
+int
+RGR_FindBestRobustRegression
+(double *x,
+ double *y,
+ int n,
+ double tol,
+ double *b0,
+ double *b1,
+ int *n_runs,
+ int *best_start);
+
+int
+RGR_MultipleRegress
+(double *x1,                    /* first independent variable */
+ double *x2,                    /* second independent variable */
+ double *y,                     /* measured data */
+
+ int n,                         /* number of data points */
+
+ /* The results */
+ double *b2                     /* estimated second slope */
+);
+
+/* Return the median value from an array */
+extern double RGR_FindMedian(double *x, int n);
+
+#endif /* GOT_REGRESS_H */
diff --git a/reports.h b/reports.h
new file mode 100644
index 0000000..6674dd9
--- /dev/null
+++ b/reports.h
@@ -0,0 +1,206 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Data structure definitions within the daemon for various reports that
+  can be generated */
+
+#ifndef GOT_REPORTS_H
+#define GOT_REPORTS_H
+
+#include "sysincl.h"
+#include "addressing.h"
+#include "ntp.h"
+
+typedef struct {
+  IPAddr ip_addr;
+  int stratum;
+  int poll;
+  enum {RPT_NTP_CLIENT, RPT_NTP_PEER, RPT_LOCAL_REFERENCE} mode;
+  enum {
+    RPT_NONSELECTABLE,
+    RPT_FALSETICKER,
+    RPT_JITTERY,
+    RPT_SELECTABLE,
+    RPT_UNSELECTED,
+    RPT_SELECTED,
+  } state;
+
+  int reachability;
+  unsigned long latest_meas_ago; /* seconds */
+  double orig_latest_meas; /* seconds */
+  double latest_meas; /* seconds */
+  double latest_meas_err; /* seconds */
+} RPT_SourceReport ;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  int stratum;
+  NTP_Leap leap_status;
+  struct timespec ref_time;
+  double current_correction;
+  double last_offset;
+  double rms_offset;
+  double freq_ppm;
+  double resid_freq_ppm;
+  double skew_ppm;
+  double root_delay;
+  double root_dispersion;
+  double last_update_interval;
+} RPT_TrackingReport;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  unsigned long n_samples;
+  unsigned long n_runs;
+  unsigned long span_seconds;
+  double resid_freq_ppm;
+  double skew_ppm;
+  double sd;
+  double est_offset;
+  double est_offset_err;
+} RPT_SourcestatsReport;
+
+typedef struct {
+  struct timespec ref_time;
+  unsigned long n_samples;
+  unsigned long n_runs;
+  unsigned long span_seconds;
+  double rtc_seconds_fast;
+  double rtc_gain_rate_ppm;
+} RPT_RTC_Report;
+
+typedef struct {
+  IPAddr ip_addr;
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint16_t ntp_drops;
+  uint16_t nke_drops;
+  uint16_t cmd_drops;
+  int8_t ntp_interval;
+  int8_t nke_interval;
+  int8_t cmd_interval;
+  int8_t ntp_timeout_interval;
+  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
+  uint32_t last_cmd_hit_ago;
+} RPT_ClientAccessByIndex_Report;
+
+typedef struct {
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint32_t ntp_drops;
+  uint32_t nke_drops;
+  uint32_t cmd_drops;
+  uint32_t log_drops;
+  uint32_t ntp_auth_hits;
+  uint32_t ntp_interleaved_hits;
+  uint32_t ntp_timestamps;
+  uint32_t ntp_span_seconds;
+} RPT_ServerStatsReport;
+
+typedef struct {
+  struct timespec when;
+  double slewed_offset;
+  double orig_offset;
+  double residual;
+} RPT_ManualSamplesReport;
+
+typedef struct {
+  int online;
+  int offline;
+  int burst_online;
+  int burst_offline;
+  int unresolved;
+} RPT_ActivityReport;
+
+typedef struct {
+  int active;
+  int leap_only;
+  double offset;
+  double freq_ppm;
+  double wander_ppm;
+  double last_update_ago;
+  double remaining_time;
+} RPT_SmoothingReport;
+
+typedef struct {
+  IPAddr remote_addr;
+  IPAddr local_addr;
+  uint16_t remote_port;
+  uint8_t leap;
+  uint8_t version;
+  uint8_t mode;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  double root_delay;
+  double root_dispersion;
+  uint32_t ref_id;
+  struct timespec ref_time;
+  double offset;
+  double peer_delay;
+  double peer_dispersion;
+  double response_time;
+  double jitter_asymmetry;
+  uint16_t tests;
+  int interleaved;
+  int authenticated;
+  char tx_tss_char;
+  char rx_tss_char;
+  uint32_t total_tx_count;
+  uint32_t total_rx_count;
+  uint32_t total_valid_count;
+  uint32_t total_good_count;
+} RPT_NTPReport;
+
+typedef struct {
+  NTP_AuthMode mode;
+  uint32_t key_id;
+  int key_type;
+  int key_length;
+  int ke_attempts;
+  uint32_t last_ke_ago;
+  int cookies;
+  int cookie_length;
+  int nak;
+} RPT_AuthReport;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  char state_char;
+  int authentication;
+  NTP_Leap leap;
+  int conf_options;
+  int eff_options;
+  uint32_t last_sample_ago;
+  double score;
+  double lo_limit;
+  double hi_limit;
+} RPT_SelectReport;
+
+#endif /* GOT_REPORTS_H */
diff --git a/rtc.c b/rtc.c
new file mode 100644
index 0000000..d946541
--- /dev/null
+++ b/rtc.c
@@ -0,0 +1,242 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "rtc.h"
+#include "local.h"
+#include "logging.h"
+#include "conf.h"
+
+#if defined LINUX && defined FEAT_RTC
+#include "rtc_linux.h"
+#endif /* defined LINUX */
+
+/* ================================================== */
+
+static int driver_initialised = 0;
+static int driver_preinit_ok = 0;
+
+static struct {
+  int  (*init)(void);
+  void (*fini)(void);
+  int  (*time_pre_init)(time_t driftfile_time);
+  void (*time_init)(void (*after_hook)(void*), void *anything);
+  void (*start_measurements)(void);
+  int  (*write_parameters)(void);
+  int  (*get_report)(RPT_RTC_Report *report);
+  int  (*trim)(void);
+} driver =
+{
+#if defined LINUX && defined FEAT_RTC
+  RTC_Linux_Initialise,
+  RTC_Linux_Finalise,
+  RTC_Linux_TimePreInit,
+  RTC_Linux_TimeInit,
+  RTC_Linux_StartMeasurements,
+  RTC_Linux_WriteParameters,
+  RTC_Linux_GetReport,
+  RTC_Linux_Trim
+#else
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL
+#endif 
+};
+     
+/* ================================================== */
+/* Get the last modification time of the driftfile */
+
+static time_t
+get_driftfile_time(void)
+{
+  struct stat buf;
+  char *drift_file;
+
+  drift_file = CNF_GetDriftFile();
+  if (!drift_file)
+    return 0;
+
+  if (stat(drift_file, &buf))
+    return 0;
+
+  return buf.st_mtime;
+}
+
+/* ================================================== */
+/* Set the system time to the driftfile time if it's in the future */
+
+static void
+apply_driftfile_time(time_t t)
+{
+  struct timespec now;
+
+  LCL_ReadCookedTime(&now, NULL);
+
+  if (now.tv_sec < t) {
+    if (LCL_ApplyStepOffset(now.tv_sec - t))
+      LOG(LOGS_INFO, "System time restored from driftfile");
+  }
+}
+
+/* ================================================== */
+
+void
+RTC_Initialise(int initial_set)
+{
+  time_t driftfile_time;
+  char *file_name;
+
+  /* If the -s option was specified, try to do an initial read of the RTC and
+     set the system time to it.  Also, read the last modification time of the
+     driftfile (i.e. system time when chronyd was previously stopped) and set
+     the system time to it if it's in the future to bring the clock closer to
+     the true time when the RTC is broken (e.g. it has no battery), is missing,
+     or there is no RTC driver. */
+  if (initial_set) {
+    driftfile_time = get_driftfile_time();
+
+    if (driver.time_pre_init && driver.time_pre_init(driftfile_time)) {
+      driver_preinit_ok = 1;
+    } else {
+      driver_preinit_ok = 0;
+      if (driftfile_time)
+        apply_driftfile_time(driftfile_time);
+    }
+  }
+
+  driver_initialised = 0;
+
+  /* This is how we tell whether the user wants to load the RTC
+     driver, if he is on a machine where it is an option. */
+  file_name = CNF_GetRtcFile();
+
+  if (file_name) {
+    if (CNF_GetRtcSync()) {
+      LOG_FATAL("rtcfile directive cannot be used with rtcsync");
+    }
+
+    if (driver.init) {
+      if ((driver.init)()) {
+        driver_initialised = 1;
+      } else {
+        LOG(LOGS_ERR, "RTC driver could not be initialised");
+      }
+    } else {
+      LOG(LOGS_ERR, "RTC not supported on this operating system");
+    }
+  }
+}
+
+/* ================================================== */
+
+void
+RTC_Finalise(void)
+{
+  if (driver_initialised) {
+    (driver.fini)();
+  }
+}
+
+/* ================================================== */
+/* Start the processing to get a single measurement from the real time
+   clock, and use it to trim the system time, based on knowing the
+   drift rate of the RTC and the error the last time we set it.  If the
+   TimePreInit routine has succeeded, we can be sure that the trim required
+   is not *too* large.
+
+   We are called with a hook to a function to be called after the
+   initialisation is complete.  We also call this if we cannot do the
+   initialisation. */
+
+void
+RTC_TimeInit(void (*after_hook)(void *), void *anything)
+{
+  if (driver_initialised && driver_preinit_ok) {
+    (driver.time_init)(after_hook, anything);
+  } else {
+    (after_hook)(anything);
+  }
+}
+
+/* ================================================== */
+/* Start the RTC measurement process */
+
+void
+RTC_StartMeasurements(void)
+{
+  if (driver_initialised) {
+    (driver.start_measurements)();
+  }
+  /* Benign if driver not present */
+}
+
+/* ================================================== */
+/* Write RTC information out to RTC file.  Return 0 for success, 1 if
+   RTC driver not running, or 2 if the file cannot be written. */
+
+int
+RTC_WriteParameters(void)
+{
+  if (driver_initialised) {
+    return (driver.write_parameters)();
+  } else {
+    return RTC_ST_NODRV;
+  }
+}
+
+/* ================================================== */
+
+int
+RTC_GetReport(RPT_RTC_Report *report)
+{
+  if (driver_initialised) {
+    return (driver.get_report)(report);
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+RTC_Trim(void)
+{
+  if (driver_initialised) {
+    return (driver.trim)();
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
diff --git a/rtc.h b/rtc.h
new file mode 100644
index 0000000..8fd677b
--- /dev/null
+++ b/rtc.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  */
+
+#ifndef GOT_RTC_H
+#define GOT_RTC_H
+
+#include "reports.h"
+
+extern void RTC_Initialise(int initial_set);
+extern void RTC_Finalise(void);
+extern void RTC_TimeInit(void (*after_hook)(void *), void *anything);
+extern void RTC_StartMeasurements(void);
+extern int  RTC_GetReport(RPT_RTC_Report *report);
+
+#define RTC_ST_OK 0
+#define RTC_ST_NODRV 1
+#define RTC_ST_BADFILE 2
+
+extern int RTC_WriteParameters(void);
+
+extern int RTC_Trim(void);
+
+#endif /* GOT_RTC_H */
diff --git a/rtc_linux.c b/rtc_linux.c
new file mode 100644
index 0000000..58b625b
--- /dev/null
+++ b/rtc_linux.c
@@ -0,0 +1,1072 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2012-2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Real-time clock driver for linux.  This interfaces the program with
+  the clock that keeps time when the machine is turned off.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <linux/rtc.h>
+
+#include "logging.h"
+#include "sched.h"
+#include "local.h"
+#include "util.h"
+#include "sys_linux.h"
+#include "reference.h"
+#include "regress.h"
+#include "rtc.h"
+#include "rtc_linux.h"
+#include "conf.h"
+#include "memory.h"
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void measurement_timeout(void *any);
+
+static void read_from_device(int fd_, int event, void *any);
+
+/* ================================================== */
+
+typedef enum {
+  OM_NORMAL,
+  OM_INITIAL,
+  OM_AFTERTRIM
+} OperatingMode;
+
+static OperatingMode operating_mode = OM_NORMAL;
+
+/* ================================================== */
+
+static int fd;
+
+#define LOWEST_MEASUREMENT_PERIOD 15
+#define HIGHEST_MEASUREMENT_PERIOD 480
+#define N_SAMPLES_PER_REGRESSION 1
+
+static int measurement_period = LOWEST_MEASUREMENT_PERIOD;
+
+static SCH_TimeoutID timeout_id = 0;
+
+static int skip_interrupts;
+
+/* ================================================== */
+
+/* Maximum number of samples held */
+#define MAX_SAMPLES 64
+
+/* Real time clock samples.  We store the seconds count as originally
+   measured. */
+static time_t *rtc_sec = NULL;
+
+/* Reference time, against which delta times on the RTC scale are measured */
+static time_t rtc_ref;
+
+/* System clock samples associated with the above samples. */
+static struct timespec *system_times = NULL;
+
+/* Number of samples currently stored. */
+static int n_samples;   
+
+/* Number of new samples since last regression */
+static int n_samples_since_regression;
+
+/* Number of runs of residuals in last regression (for logging) */
+static int n_runs;
+
+/* Coefficients */
+/* Whether they are valid */
+static int coefs_valid;
+
+/* Reference time */
+static time_t coef_ref_time;
+/* Number of seconds by which RTC was fast of the system time at coef_ref_time */
+static double coef_seconds_fast;
+
+/* Estimated number of seconds that RTC gains relative to system time
+   for each second of ITS OWN time */
+static double coef_gain_rate;
+
+/* Gain rate saved just before we step the RTC to correct it to the
+   nearest second, so that we can write a useful set of coefs to the
+   RTC data file once we have reacquired its offset after the step */
+static double saved_coef_gain_rate;
+
+/* Threshold for automatic RTC trimming in seconds, zero when disabled */
+static double autotrim_threshold;
+
+/* Filename supplied by config file where RTC coefficients are
+   stored. */
+static char *coefs_file_name;
+
+/* ================================================== */
+/* Coefficients read from file at start of run. */
+
+/* Whether we have tried to load the coefficients */
+static int tried_to_load_coefs = 0;
+
+/* Whether valid coefficients were read */
+static int valid_coefs_from_file = 0;
+
+/* Coefs read in */
+static time_t file_ref_time;
+static double file_ref_offset, file_rate_ppm;
+
+/* ================================================== */
+
+/* Flag to remember whether to assume the RTC is running on UTC */
+static int rtc_on_utc;
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+
+static void (*after_init_hook)(void *) = NULL;
+static void *after_init_hook_arg = NULL;
+
+/* ================================================== */
+
+static void
+discard_samples(int new_first)
+{
+  int n_to_save;
+
+  assert(new_first >= 0 && new_first < n_samples);
+
+  n_to_save = n_samples - new_first;
+
+  memmove(rtc_sec, rtc_sec + new_first, n_to_save * sizeof(time_t));
+  memmove(system_times, system_times + new_first, n_to_save * sizeof(struct timespec));
+
+  n_samples = n_to_save;
+}
+
+/* ================================================== */
+
+#define NEW_FIRST_WHEN_FULL 4
+
+static void
+accumulate_sample(time_t rtc, struct timespec *sys)
+{
+
+  if (n_samples == MAX_SAMPLES) {
+    /* Discard oldest samples */
+    discard_samples(NEW_FIRST_WHEN_FULL);
+  }
+
+  /* Discard all samples if the RTC was stepped back (not our trim) */
+  if (n_samples > 0 && rtc_sec[n_samples - 1] >= rtc) {
+    DEBUG_LOG("RTC samples discarded");
+    n_samples = 0;
+  }
+
+  /* Always use most recent sample as reference */
+  rtc_ref = rtc;
+  rtc_sec[n_samples] = rtc;
+  system_times[n_samples] = *sys;
+  ++n_samples_since_regression;
+  ++n_samples;
+}
+
+/* ================================================== */
+/* The new_sample flag is to indicate whether to adjust the
+   measurement period depending on the behaviour of the standard
+   deviation. */
+
+static void
+run_regression(int new_sample,
+               int *valid,
+               time_t *ref,
+               double *fast,
+               double *slope)
+{
+  double rtc_rel[MAX_SAMPLES]; /* Relative times on RTC axis */
+  double offsets[MAX_SAMPLES]; /* How much the RTC is fast of the system clock */
+  int i;
+  double est_intercept, est_slope;
+  int best_new_start;
+
+  if (n_samples > 0) {
+
+    for (i=0; i<n_samples; i++) {
+      rtc_rel[i] = (double)(rtc_sec[i] - rtc_ref);
+      offsets[i] = ((double) (rtc_ref - system_times[i].tv_sec) -
+                    (1.0e-9 * system_times[i].tv_nsec) +
+                    rtc_rel[i]);
+
+    }
+
+    if (RGR_FindBestRobustRegression
+        (rtc_rel, offsets,
+         n_samples, 1.0e-9,
+         &est_intercept, &est_slope,
+         &n_runs,
+         &best_new_start)) {
+
+      /* Calculate and store coefficients.  We don't do any error
+         bounds processing on any of these. */
+      *valid = 1;
+      *ref = rtc_ref;
+      *fast = est_intercept;
+      *slope = est_slope;
+
+      if (best_new_start > 0) {
+        discard_samples(best_new_start);
+      }
+
+
+    } else {
+      /* Keep existing coefficients. */
+    }
+  } else {
+    /* Keep existing coefficients. */
+  }
+
+}
+
+/* ================================================== */
+
+static void
+slew_samples
+(struct timespec *raw, struct timespec *cooked,
+ double dfreq,
+ double doffset,
+ LCL_ChangeType change_type,
+ void *anything)
+{
+  int i;
+  double delta_time;
+  double old_seconds_fast, old_gain_rate;
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    /* Drop all samples. */
+    n_samples = 0;
+  }
+
+  for (i=0; i<n_samples; i++) {
+    UTI_AdjustTimespec(system_times + i, cooked, system_times + i, &delta_time,
+        dfreq, doffset);
+  }
+
+  old_seconds_fast = coef_seconds_fast;
+  old_gain_rate = coef_gain_rate;
+
+  if (coefs_valid) {
+    coef_seconds_fast += doffset;
+    coef_gain_rate += dfreq * (1.0 - coef_gain_rate);
+  }
+
+  DEBUG_LOG("dfreq=%.8f doffset=%.6f old_fast=%.6f old_rate=%.3f new_fast=%.6f new_rate=%.3f",
+      dfreq, doffset,
+      old_seconds_fast, 1.0e6 * old_gain_rate,
+      coef_seconds_fast, 1.0e6 * coef_gain_rate);
+}
+
+/* ================================================== */
+
+/* Function to convert from a time_t value represenging UTC to the
+   corresponding real time clock 'DMY HMS' form, taking account of
+   whether the user runs his RTC on the local time zone or UTC */
+
+static struct tm *
+rtc_from_t(const time_t *t)
+{
+  if (rtc_on_utc) {
+    return gmtime(t);
+  } else {
+    return localtime(t);
+  }
+}
+
+/* ================================================== */
+
+/* Inverse function to get back from RTC 'DMY HMS' form to time_t UTC
+   form.  This essentially uses mktime(), but involves some awful
+   complexity to cope with timezones.  The problem is that mktime's
+   behaviour with regard to the daylight saving flag in the 'struct
+   tm' does not seem to be reliable across all systems, unless that
+   flag is set to zero. 
+
+   tm_isdst = -1 does not seem to work with all libc's - it is treated
+   as meaning there is DST, or fails completely.  (It is supposed to
+   use the timezone info to work out whether summer time is active at
+   the specified epoch).
+
+   tm_isdst = 1 fails if the local timezone has no summer time defined.
+
+   The approach taken is as follows.  Suppose the RTC is on localtime.
+   We perform all mktime calls with the tm_isdst field set to zero.
+
+   Let y be the RTC reading in 'DMY HMS' form.  Let M be the mktime
+   function with tm_isdst=0 and L be the localtime function.
+
+   We seek x such that y = L(x).  Now there will exist a value Z(t)
+   such that M(L(t)) = t + Z(t) for all t, where Z(t) depends on
+   whether daylight saving is active at time t.
+
+   We want L(x) = y.  Therefore M(L(x)) = x + Z = M(y).  But
+   M(L(M(y))) = M(y) + Z.  Therefore x = M(y) - Z = M(y) - (M(L(M(y)))
+   - M(y)).
+
+   The case for the RTC running on UTC is identical but without the
+   potential complication that Z depends on t.
+*/
+
+static time_t
+t_from_rtc(struct tm *stm) {
+  struct tm temp1, temp2, *tm;
+  long diff;
+  time_t t1, t2;
+
+  temp1 = *stm;
+  temp1.tm_isdst = 0;
+  
+  t1 = mktime(&temp1);
+
+  tm = rtc_on_utc ? gmtime(&t1) : localtime(&t1);
+  if (!tm) {
+    DEBUG_LOG("gmtime()/localtime() failed");
+    return -1;
+  }
+
+  temp2 = *tm;
+  temp2.tm_isdst = 0;
+  t2 = mktime(&temp2);
+  diff = t2 - t1;
+
+  if (t1 - diff == -1)
+    DEBUG_LOG("Could not convert RTC time");
+
+  return t1 - diff;
+}
+
+/* ================================================== */
+
+static void
+read_hwclock_file(const char *hwclock_file)
+{
+  FILE *in;
+  char line[256];
+  int i;
+
+  if (!hwclock_file || !hwclock_file[0])
+    return;
+
+  in = UTI_OpenFile(NULL, hwclock_file, NULL, 'r', 0);
+  if (!in)
+    return;
+
+  /* Read third line from the file. */
+  for (i = 0; i < 3; i++) {
+    if (!fgets(line, sizeof(line), in))
+      break;
+  }
+
+  fclose(in);
+
+  if (i == 3 && !strncmp(line, "LOCAL", 5)) {
+    rtc_on_utc = 0;
+  } else if (i == 3 && !strncmp(line, "UTC", 3)) {
+    rtc_on_utc = 1;
+  } else {
+    LOG(LOGS_WARN, "Could not read RTC LOCAL/UTC setting from %s", hwclock_file);
+  }
+}
+
+/* ================================================== */
+
+static void
+setup_config(void)
+{
+  if (CNF_GetRtcOnUtc()) {
+    rtc_on_utc = 1;
+  } else {
+    rtc_on_utc = 0;
+  }
+
+  read_hwclock_file(CNF_GetHwclockFile());
+
+  autotrim_threshold = CNF_GetRtcAutotrim();
+}
+
+/* ================================================== */
+/* Read the coefficients from the file where they were saved
+   the last time the program was run. */
+
+static void
+read_coefs_from_file(void)
+{
+  double ref_time;
+  FILE *in;
+
+  if (!tried_to_load_coefs) {
+
+    valid_coefs_from_file = 0; /* only gets set true if we succeed */
+
+    tried_to_load_coefs = 1;
+
+    if (coefs_file_name &&
+        (in = UTI_OpenFile(NULL, coefs_file_name, NULL, 'r', 0))) {
+      if (fscanf(in, "%d%lf%lf%lf",
+                 &valid_coefs_from_file,
+                 &ref_time,
+                 &file_ref_offset,
+                 &file_rate_ppm) == 4) {
+        file_ref_time = ref_time;
+      } else {
+        LOG(LOGS_WARN, "Could not read coefficients from %s", coefs_file_name);
+      }
+      fclose(in);
+    }
+  }
+}
+
+/* ================================================== */
+/* Write the coefficients to the file where they will be read
+   the next time the program is run. */
+
+static int
+write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
+{
+  FILE *out;
+
+  /* Create a temporary file with a '.tmp' extension. */
+  out = UTI_OpenFile(NULL, coefs_file_name, ".tmp", 'w', 0644);
+  if (!out)
+    return RTC_ST_BADFILE;
+
+  /* Gain rate is written out in ppm */
+  fprintf(out, "%1d %.0f %.6f %.3f\n", valid, (double)ref_time, offset, 1.0e6 * rate);
+  fclose(out);
+
+  /* Rename the temporary file to the correct location */
+  if (!UTI_RenameTempFile(NULL, coefs_file_name, ".tmp", NULL))
+    return RTC_ST_BADFILE;
+
+  return RTC_ST_OK;
+}
+
+/* ================================================== */
+
+static int
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return 0;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+/* file_name is the name of the file where we save the RTC params
+   between executions.  Return status is whether we could initialise
+   on this version of the system. */
+
+int
+RTC_Linux_Initialise(void)
+{
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
+  rtc_sec = MallocArray(time_t, MAX_SAMPLES);
+  system_times = MallocArray(struct timespec, MAX_SAMPLES);
+
+  /* Setup details depending on configuration options */
+  setup_config();
+
+  /* In case it didn't get done by pre-init */
+  coefs_file_name = CNF_GetRtcFile();
+
+  n_samples = 0;
+  n_samples_since_regression = 0;
+  n_runs = 0;
+  coefs_valid = 0;
+
+  measurement_period = LOWEST_MEASUREMENT_PERIOD;
+
+  operating_mode = OM_NORMAL;
+
+  /* Register file handler */
+  SCH_AddFileHandler(fd, SCH_FILE_INPUT, read_from_device, NULL);
+
+  /* Register slew handler */
+  LCL_AddParameterChangeHandler(slew_samples, NULL);
+
+  logfileid = CNF_GetLogRtc() ? LOG_FileOpen("rtc",
+      "   Date (UTC) Time   RTC fast (s) Val   Est fast (s)   Slope (ppm)  Ns  Nr Meas")
+    : -1;
+  return 1;
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_Finalise(void)
+{
+  SCH_RemoveTimeout(timeout_id);
+  timeout_id = 0;
+
+  /* Remove input file handler */
+  if (fd >= 0) {
+    SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
+    close(fd);
+
+    /* Save the RTC data */
+    (void) RTC_Linux_WriteParameters();
+
+  }
+
+  if (rtc_sec)
+    LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+
+  Free(rtc_sec);
+  Free(system_times);
+}
+
+/* ================================================== */
+
+static void
+measurement_timeout(void *any)
+{
+  timeout_id = 0;
+  switch_interrupts(1);
+}
+
+/* ================================================== */
+
+static void
+set_rtc(time_t new_rtc_time)
+{
+  struct tm rtc_tm;
+  struct rtc_time rtc_raw;
+  int status;
+
+  rtc_tm = *rtc_from_t(&new_rtc_time);
+
+  rtc_raw.tm_sec = rtc_tm.tm_sec;
+  rtc_raw.tm_min = rtc_tm.tm_min;
+  rtc_raw.tm_hour = rtc_tm.tm_hour;
+  rtc_raw.tm_mday = rtc_tm.tm_mday;
+  rtc_raw.tm_mon = rtc_tm.tm_mon;
+  rtc_raw.tm_year = rtc_tm.tm_year;
+  rtc_raw.tm_wday = rtc_tm.tm_wday;
+  rtc_raw.tm_yday = rtc_tm.tm_yday;
+  rtc_raw.tm_isdst = rtc_tm.tm_isdst;
+
+  status = ioctl(fd, RTC_SET_TIME, &rtc_raw);
+  if (status < 0) {
+    LOG(LOGS_ERR, "Could not set RTC time");
+  }
+
+}
+
+/* ================================================== */
+
+static void
+handle_initial_trim(void)
+{
+  double rate;
+  long delta_time;
+  double rtc_error_now, sys_error_now;
+
+    /* The idea is to accumulate some number of samples at 1 second
+       intervals, then do a robust regression fit to this.  This
+       should give a good fix on the intercept (=system clock error
+       rel to RTC) at a particular time, removing risk of any
+       particular sample being an outlier.  We can then look at the
+       elapsed interval since the epoch recorded in the RTC file,
+       and correct the system time accordingly. */
+    
+  run_regression(1, &coefs_valid, &coef_ref_time, &coef_seconds_fast, &coef_gain_rate);
+
+  n_samples_since_regression = 0;
+  n_samples = 0;
+
+  read_coefs_from_file();
+
+  if (valid_coefs_from_file) {
+    /* Can process data */
+    delta_time = coef_ref_time - file_ref_time;
+    rate = 1.0e-6 * file_rate_ppm;
+    rtc_error_now = file_ref_offset + rate * (double) delta_time;
+          
+    /* sys_error_now is positive if the system clock is fast */
+    sys_error_now = rtc_error_now - coef_seconds_fast;
+          
+    LCL_AccumulateOffset(sys_error_now, 0.0);
+    LOG(LOGS_INFO, "System clock off from RTC by %f seconds (slew)",
+        sys_error_now);
+  } else {
+    LOG(LOGS_WARN, "No valid rtcfile coefficients");
+  }
+  
+  coefs_valid = 0;
+  
+  (after_init_hook)(after_init_hook_arg);
+  
+  operating_mode = OM_NORMAL;
+}
+
+/* ================================================== */
+
+static void
+handle_relock_after_trim(void)
+{
+  int valid;
+  time_t ref;
+  double fast, slope;
+
+  valid = 0;
+  run_regression(1, &valid, &ref, &fast, &slope);
+
+  if (valid) {
+    write_coefs_to_file(1,ref,fast,saved_coef_gain_rate);
+  } else {
+    DEBUG_LOG("Could not do regression after trim");
+  }
+
+  coefs_valid = 0;
+  n_samples = 0;
+  n_samples_since_regression = 0;
+  operating_mode = OM_NORMAL;
+  measurement_period = LOWEST_MEASUREMENT_PERIOD;
+}
+
+/* ================================================== */
+
+static void
+maybe_autotrim(void)
+{
+  /* Trim only when in normal mode, the coefficients are fresh, the current
+     offset is above the threshold and the system clock is synchronized */
+
+  if (operating_mode != OM_NORMAL || !coefs_valid || n_samples_since_regression)
+    return;
+  
+  if (autotrim_threshold <= 0.0 || fabs(coef_seconds_fast) < autotrim_threshold)
+    return;
+
+  if (REF_GetOurStratum() >= 16)
+    return;
+
+  RTC_Linux_Trim();
+}
+
+/* ================================================== */
+
+static void
+process_reading(time_t rtc_time, struct timespec *system_time)
+{
+  double rtc_fast;
+
+  accumulate_sample(rtc_time, system_time);
+
+  switch (operating_mode) {
+    case OM_NORMAL:
+
+      if (n_samples_since_regression >= N_SAMPLES_PER_REGRESSION) {
+        run_regression(1, &coefs_valid, &coef_ref_time, &coef_seconds_fast, &coef_gain_rate);
+        n_samples_since_regression = 0;
+        maybe_autotrim();
+      }
+      
+      break;
+    case OM_INITIAL:
+      if (n_samples_since_regression >= 8) {
+        handle_initial_trim();
+      }
+      break;
+    case OM_AFTERTRIM:
+      if (n_samples_since_regression >= 8) {
+        handle_relock_after_trim();
+      }
+      break;
+    default:
+      assert(0);
+      break;
+  }  
+
+
+  if (logfileid != -1) {
+    rtc_fast = (rtc_time - system_time->tv_sec) - 1.0e-9 * system_time->tv_nsec;
+
+    LOG_FileWrite(logfileid, "%s %14.6f %1d  %14.6f  %12.3f  %2d  %2d %4d",
+            UTI_TimeToLogForm(system_time->tv_sec),
+            rtc_fast,
+            coefs_valid,
+            coef_seconds_fast, coef_gain_rate * 1.0e6, n_samples, n_runs, measurement_period);
+  }    
+
+}
+
+/* ================================================== */
+
+static void
+read_from_device(int fd_, int event, void *any)
+{
+  int status;
+  unsigned long data;
+  struct timespec sys_time;
+  struct rtc_time rtc_raw;
+  struct tm rtc_tm;
+  time_t rtc_t;
+  int error = 0;
+
+  status = read(fd, &data, sizeof(data));
+
+  if (status < 0) {
+    /* This looks like a bad error : the file descriptor was indicating it was
+     * ready to read but we couldn't read anything.  Give up. */
+    LOG(LOGS_ERR, "Could not read flags %s : %s", CNF_GetRtcDevice(), strerror(errno));
+    SCH_RemoveFileHandler(fd);
+    switch_interrupts(0); /* Likely to raise error too, but just to be sure... */
+    close(fd);
+    fd = -1;
+    return;
+  }    
+
+  if (skip_interrupts > 0) {
+    /* Wait for the next interrupt, this one may be bogus */
+    skip_interrupts--;
+    return;
+  }
+
+  if ((data & RTC_UF) == RTC_UF) {
+    /* Update interrupt detected */
+    
+    /* Read RTC time, sandwiched between two polls of the system clock
+       so we can bound any error. */
+
+    SCH_GetLastEventTime(&sys_time, NULL, NULL);
+
+    status = ioctl(fd, RTC_RD_TIME, &rtc_raw);
+    if (status < 0) {
+      LOG(LOGS_ERR, "Could not read time from %s : %s", CNF_GetRtcDevice(), strerror(errno));
+      error = 1;
+      goto turn_off_interrupt;
+    }
+
+    /* Convert RTC time into a struct timespec */
+    rtc_tm.tm_sec = rtc_raw.tm_sec;
+    rtc_tm.tm_min = rtc_raw.tm_min;
+    rtc_tm.tm_hour = rtc_raw.tm_hour;
+    rtc_tm.tm_mday = rtc_raw.tm_mday;
+    rtc_tm.tm_mon = rtc_raw.tm_mon;
+    rtc_tm.tm_year = rtc_raw.tm_year;
+
+    rtc_t = t_from_rtc(&rtc_tm);
+
+    if (rtc_t == (time_t)(-1)) {
+      error = 1;
+      goto turn_off_interrupt;
+    }      
+
+    process_reading(rtc_t, &sys_time);
+
+    if (n_samples < 4) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD;
+    } else if (n_samples < 6) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 1;
+    } else if (n_samples < 10) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 2;
+    } else if (n_samples < 14) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 3;
+    } else {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 4;
+    }
+
+  }
+
+turn_off_interrupt:
+
+  switch (operating_mode) {
+    case OM_INITIAL:
+      if (error) {
+        DEBUG_LOG("Could not complete initial step due to errors");
+        operating_mode = OM_NORMAL;
+        (after_init_hook)(after_init_hook_arg);
+
+        switch_interrupts(0);
+    
+        timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+      }
+
+      break;
+
+    case OM_AFTERTRIM:
+      if (error) {
+        DEBUG_LOG("Could not complete after trim relock due to errors");
+        operating_mode = OM_NORMAL;
+
+        switch_interrupts(0);
+    
+        timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+      }
+      
+      break;
+
+    case OM_NORMAL:
+      switch_interrupts(0);
+    
+      timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+
+      break;
+    default:
+      assert(0);
+      break;
+  }
+
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_TimeInit(void (*after_hook)(void *), void *anything)
+{
+  after_init_hook = after_hook;
+  after_init_hook_arg = anything;
+
+  operating_mode = OM_INITIAL;
+  timeout_id = 0;
+  switch_interrupts(1);
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_StartMeasurements(void)
+{
+  measurement_timeout(NULL);
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_WriteParameters(void)
+{
+  int retval;
+
+  if (fd < 0) {
+    return RTC_ST_NODRV;
+  }
+  
+  if (coefs_valid) {
+    retval = write_coefs_to_file(1,coef_ref_time, coef_seconds_fast, coef_gain_rate);
+  } else {
+   /* Don't change the existing file, it may not be 100% valid but is our
+      current best guess. */
+    retval = RTC_ST_OK; /*write_coefs_to_file(0,0,0.0,0.0); */
+  }
+
+  return(retval);
+}
+
+/* ================================================== */
+/* Try to set the system clock from the RTC, in the same manner as
+   /sbin/hwclock -s would do.  We're not as picky about OS version
+   etc in this case, since we have fewer requirements regarding the
+   RTC behaviour than we do for the rest of the module. */
+
+int
+RTC_Linux_TimePreInit(time_t driftfile_time)
+{
+  int fd, status;
+  struct rtc_time rtc_raw, rtc_raw_retry;
+  struct tm rtc_tm;
+  time_t rtc_t;
+  double accumulated_error, sys_offset;
+  struct timespec new_sys_time, old_sys_time;
+
+  coefs_file_name = CNF_GetRtcFile();
+
+  setup_config();
+  read_coefs_from_file();
+
+  fd = open(CNF_GetRtcDevice(), O_RDONLY);
+
+  if (fd < 0) {
+    return 0; /* Can't open it, and won't be able to later */
+  }
+
+  /* Retry reading the rtc until both read attempts give the same sec value.
+     This way the race condition is prevented that the RTC has updated itself
+     during the first read operation. */
+  do {
+    status = ioctl(fd, RTC_RD_TIME, &rtc_raw);
+    if (status >= 0) {
+      status = ioctl(fd, RTC_RD_TIME, &rtc_raw_retry);
+    }
+  } while (status >= 0 && rtc_raw.tm_sec != rtc_raw_retry.tm_sec);
+
+  /* Read system clock */
+  LCL_ReadCookedTime(&old_sys_time, NULL);
+
+  close(fd);
+
+  if (status >= 0) {
+    /* Convert to seconds since 1970 */
+    rtc_tm.tm_sec = rtc_raw.tm_sec;
+    rtc_tm.tm_min = rtc_raw.tm_min;
+    rtc_tm.tm_hour = rtc_raw.tm_hour;
+    rtc_tm.tm_mday = rtc_raw.tm_mday;
+    rtc_tm.tm_mon = rtc_raw.tm_mon;
+    rtc_tm.tm_year = rtc_raw.tm_year;
+    
+    rtc_t = t_from_rtc(&rtc_tm);
+
+    if (rtc_t != (time_t)(-1)) {
+
+      /* Work out approximatation to correct time (to about the
+         nearest second) */
+      if (valid_coefs_from_file) {
+        accumulated_error = file_ref_offset +
+          (rtc_t - file_ref_time) * 1.0e-6 * file_rate_ppm;
+      } else {
+        accumulated_error = 0.0;
+      }
+
+      /* Correct time */
+
+      new_sys_time.tv_sec = rtc_t;
+      /* Average error in the RTC reading */
+      new_sys_time.tv_nsec = 500000000;
+
+      UTI_AddDoubleToTimespec(&new_sys_time, -accumulated_error, &new_sys_time);
+
+      if (new_sys_time.tv_sec < driftfile_time) {
+        LOG(LOGS_WARN, "RTC time before last driftfile modification (ignored)");
+        return 0;
+      }
+
+      sys_offset = UTI_DiffTimespecsToDouble(&old_sys_time, &new_sys_time);
+
+      /* Set system time only if the step is larger than 1 second */
+      if (fabs(sys_offset) >= 1.0) {
+        if (LCL_ApplyStepOffset(sys_offset))
+          LOG(LOGS_INFO, "System time set from RTC");
+      }
+    } else {
+      return 0;
+    }
+  } else {
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_GetReport(RPT_RTC_Report *report)
+{
+  report->ref_time.tv_sec = coef_ref_time;
+  report->ref_time.tv_nsec = 0;
+  report->n_samples = n_samples;
+  report->n_runs = n_runs;
+  if (n_samples > 1) {
+    report->span_seconds = rtc_sec[n_samples - 1] - rtc_sec[0];
+  } else {
+    report->span_seconds = 0;
+  }
+  report->rtc_seconds_fast = coef_seconds_fast;
+  report->rtc_gain_rate_ppm = 1.0e6 * coef_gain_rate;
+  return 1;
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_Trim(void)
+{
+  struct timespec now;
+
+  /* Remember the slope coefficient - we won't be able to determine a
+     good one in a few seconds when we determine the new offset! */
+  saved_coef_gain_rate = coef_gain_rate;
+
+  if (fabs(coef_seconds_fast) > 1.0) {
+
+    LOG(LOGS_INFO, "RTC wrong by %.3f seconds (step)",
+        coef_seconds_fast);
+
+    /* Do processing to set clock.  Let R be the value we set the
+       RTC to, then in 500ms the RTC ticks (R+1) (see comments in
+       arch/i386/kernel/time.c about the behaviour of the real time
+       clock chip).  If S is the system time now, the error at the
+       next RTC tick is given by E = (R+1) - (S+0.5).  Ideally we
+       want |E| <= 0.5, which implies R <= S <= R+1, i.e. R is just
+       the rounded down part of S, i.e. the seconds part. */
+
+    LCL_ReadCookedTime(&now, NULL);
+    
+    set_rtc(now.tv_sec);
+
+    /* All old samples will now look bogus under the new
+           regime. */
+    n_samples = 0;
+    operating_mode = OM_AFTERTRIM;
+
+    /* Estimate the offset in case writertc is called or chronyd
+       is terminated during rapid sampling */
+    coef_seconds_fast = -now.tv_nsec / 1.0e9 + 0.5;
+    coef_ref_time = now.tv_sec;
+
+    /* And start rapid sampling, interrupts on now */
+    SCH_RemoveTimeout(timeout_id);
+    timeout_id = 0;
+    switch_interrupts(1);
+  }
+
+  return 1;
+  
+}
diff --git a/rtc_linux.h b/rtc_linux.h
new file mode 100644
index 0000000..fa33ef1
--- /dev/null
+++ b/rtc_linux.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  ======================================================================
+
+  */
+
+#ifndef _GOT_RTC_LINUX_H
+#define _GOT_RTC_LINUX_H
+
+#include "reports.h"
+
+extern int RTC_Linux_Initialise(void);
+extern void RTC_Linux_Finalise(void);
+extern int RTC_Linux_TimePreInit(time_t driftile_time);
+extern void RTC_Linux_TimeInit(void (*after_hook)(void *), void *anything);
+extern void RTC_Linux_StartMeasurements(void);
+
+/* 0=success, 1=no driver, 2=can't write file */
+extern int RTC_Linux_WriteParameters(void);
+
+extern int RTC_Linux_GetReport(RPT_RTC_Report *report);
+extern int RTC_Linux_Trim(void);
+
+extern void RTC_Linux_CycleLogFile(void);
+
+#endif /* _GOT_RTC_LINUX_H */
diff --git a/samplefilt.c b/samplefilt.c
new file mode 100644
index 0000000..9b81a76
--- /dev/null
+++ b/samplefilt.c
@@ -0,0 +1,497 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009-2011, 2014, 2016, 2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing a median sample filter.
+
+  */
+
+#include "config.h"
+
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "regress.h"
+#include "samplefilt.h"
+#include "util.h"
+
+#define MIN_SAMPLES 1
+#define MAX_SAMPLES 256
+
+struct SPF_Instance_Record {
+  int min_samples;
+  int max_samples;
+  int index;
+  int used;
+  int last;
+  int avg_var_n;
+  double avg_var;
+  double max_var;
+  double combine_ratio;
+  NTP_Sample *samples;
+  int *selected;
+  double *x_data;
+  double *y_data;
+  double *w_data;
+};
+
+/* ================================================== */
+
+SPF_Instance
+SPF_CreateInstance(int min_samples, int max_samples, double max_dispersion, double combine_ratio)
+{
+  SPF_Instance filter;
+
+  filter = MallocNew(struct SPF_Instance_Record);
+
+  min_samples = CLAMP(MIN_SAMPLES, min_samples, MAX_SAMPLES);
+  max_samples = CLAMP(MIN_SAMPLES, max_samples, MAX_SAMPLES);
+  max_samples = MAX(min_samples, max_samples);
+  combine_ratio = CLAMP(0.0, combine_ratio, 1.0);
+
+  filter->min_samples = min_samples;
+  filter->max_samples = max_samples;
+  filter->index = -1;
+  filter->used = 0;
+  filter->last = -1;
+  /* Set the first estimate to the system precision */
+  filter->avg_var_n = 0;
+  filter->avg_var = SQUARE(LCL_GetSysPrecisionAsQuantum());
+  filter->max_var = SQUARE(max_dispersion);
+  filter->combine_ratio = combine_ratio;
+  filter->samples = MallocArray(NTP_Sample, filter->max_samples);
+  filter->selected = MallocArray(int, filter->max_samples);
+  filter->x_data = MallocArray(double, filter->max_samples);
+  filter->y_data = MallocArray(double, filter->max_samples);
+  filter->w_data = MallocArray(double, filter->max_samples);
+
+  return filter;
+}
+
+/* ================================================== */
+
+void
+SPF_DestroyInstance(SPF_Instance filter)
+{
+  Free(filter->samples);
+  Free(filter->selected);
+  Free(filter->x_data);
+  Free(filter->y_data);
+  Free(filter->w_data);
+  Free(filter);
+}
+
+/* ================================================== */
+
+/* Check that samples times are strictly increasing */
+
+static int
+check_sample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (filter->used <= 0)
+    return 1;
+
+  if (UTI_CompareTimespecs(&filter->samples[filter->last].time, &sample->time) >= 0) {
+    DEBUG_LOG("filter non-increasing sample time %s", UTI_TimespecToString(&sample->time));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_AccumulateSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (!check_sample(filter, sample))
+      return 0;
+
+  filter->index++;
+  filter->index %= filter->max_samples;
+  filter->last = filter->index;
+  if (filter->used < filter->max_samples)
+    filter->used++;
+
+  filter->samples[filter->index] = *sample;
+
+  DEBUG_LOG("filter sample %d t=%s offset=%.9f peer_disp=%.9f",
+            filter->index, UTI_TimespecToString(&sample->time),
+            sample->offset, sample->peer_dispersion);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetLastSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (filter->last < 0)
+    return 0;
+
+  *sample = filter->samples[filter->last];
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetNumberOfSamples(SPF_Instance filter)
+{
+  return filter->used;
+}
+
+/* ================================================== */
+
+int
+SPF_GetMaxSamples(SPF_Instance filter)
+{
+  return filter->max_samples;
+}
+
+/* ================================================== */
+
+double
+SPF_GetAvgSampleDispersion(SPF_Instance filter)
+{
+  return sqrt(filter->avg_var);
+}
+
+/* ================================================== */
+
+static void
+drop_samples(SPF_Instance filter, int keep_last)
+{
+  filter->index = -1;
+  filter->used = 0;
+  if (!keep_last)
+    filter->last = -1;
+}
+
+/* ================================================== */
+
+void
+SPF_DropSamples(SPF_Instance filter)
+{
+  drop_samples(filter, 0);
+}
+
+/* ================================================== */
+
+static const NTP_Sample *tmp_sort_samples;
+
+static int
+compare_samples(const void *a, const void *b)
+{
+  const NTP_Sample *s1, *s2;
+
+  s1 = &tmp_sort_samples[*(int *)a];
+  s2 = &tmp_sort_samples[*(int *)b];
+
+  if (s1->offset < s2->offset)
+    return -1;
+  else if (s1->offset > s2->offset)
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+select_samples(SPF_Instance filter)
+{
+  int i, j, k, o, from, to, *selected;
+  double min_dispersion;
+
+  if (filter->used < filter->min_samples)
+    return 0;
+
+  selected = filter->selected;
+
+  /* With 4 or more samples, select those that have peer dispersion smaller
+     than 1.5x of the minimum dispersion */
+  if (filter->used > 4) {
+    for (i = 1, min_dispersion = filter->samples[0].peer_dispersion; i < filter->used; i++) {
+      if (min_dispersion > filter->samples[i].peer_dispersion)
+        min_dispersion = filter->samples[i].peer_dispersion;
+    }
+
+    for (i = j = 0; i < filter->used; i++) {
+      if (filter->samples[i].peer_dispersion <= 1.5 * min_dispersion)
+        selected[j++] = i;
+    }
+  } else {
+    j = 0;
+  }
+
+  if (j < 4) {
+    /* Select all samples */
+
+    for (j = 0; j < filter->used; j++)
+      selected[j] = j;
+  }
+
+  /* And sort their indices by offset */
+  tmp_sort_samples = filter->samples;
+  qsort(selected, j, sizeof (int), compare_samples);
+
+  /* Select samples closest to the median */
+  if (j > 2) {
+    from = j * (1.0 - filter->combine_ratio) / 2.0;
+    from = CLAMP(1, from, (j - 1) / 2);
+  } else {
+    from = 0;
+  }
+
+  to = j - from;
+
+  /* Mark unused samples and sort the rest by their time */
+
+  o = filter->used - filter->index - 1;
+
+  for (i = 0; i < from; i++)
+    selected[i] = -1;
+  for (; i < to; i++)
+    selected[i] = (selected[i] + o) % filter->used;
+  for (; i < filter->used; i++)
+    selected[i] = -1;
+
+  for (i = from; i < to; i++) {
+    j = selected[i];
+    selected[i] = -1;
+    while (j != -1 && selected[j] != j) {
+      k = selected[j];
+      selected[j] = j;
+      j = k;
+    }
+  }
+
+  for (i = j = 0; i < filter->used; i++) {
+    if (selected[i] != -1)
+      selected[j++] = (selected[i] + filter->used - o) % filter->used;
+  }
+
+  assert(j > 0 && j <= filter->max_samples);
+
+  return j;
+}
+
+/* ================================================== */
+
+static int
+combine_selected_samples(SPF_Instance filter, int n, NTP_Sample *result)
+{
+  double mean_peer_dispersion, mean_root_dispersion, mean_peer_delay, mean_root_delay;
+  double mean_x, mean_y, disp, var, prev_avg_var;
+  NTP_Sample *sample, *last_sample;
+  int i, dof;
+
+  last_sample = &filter->samples[filter->selected[n - 1]];
+
+  /* Prepare data */
+  for (i = 0; i < n; i++) {
+    sample = &filter->samples[filter->selected[i]];
+
+    filter->x_data[i] = UTI_DiffTimespecsToDouble(&sample->time, &last_sample->time);
+    filter->y_data[i] = sample->offset;
+    filter->w_data[i] = sample->peer_dispersion;
+  }
+
+  /* Calculate mean offset and interval since the last sample */
+  for (i = 0, mean_x = mean_y = 0.0; i < n; i++) {
+    mean_x += filter->x_data[i];
+    mean_y += filter->y_data[i];
+  }
+  mean_x /= n;
+  mean_y /= n;
+
+  if (n >= 4) {
+    double b0, b1, s2, sb0, sb1;
+
+    /* Set y axis to the mean sample time */
+    for (i = 0; i < n; i++)
+      filter->x_data[i] -= mean_x;
+
+    /* Make a linear fit and use the estimated standard deviation of the
+       intercept as dispersion */
+    RGR_WeightedRegression(filter->x_data, filter->y_data, filter->w_data, n,
+                           &b0, &b1, &s2, &sb0, &sb1);
+    var = s2;
+    disp = sb0;
+    dof = n - 2;
+  } else if (n >= 2) {
+    for (i = 0, disp = 0.0; i < n; i++)
+      disp += (filter->y_data[i] - mean_y) * (filter->y_data[i] - mean_y);
+    var = disp / (n - 1);
+    disp = sqrt(var);
+    dof = n - 1;
+  } else {
+    var = filter->avg_var;
+    disp = sqrt(var);
+    dof = 1;
+  }
+
+  /* Avoid working with zero dispersion */
+  if (var < 1e-20) {
+    var = 1e-20;
+    disp = sqrt(var);
+  }
+
+  /* Drop the sample if the variance is larger than the maximum */
+  if (filter->max_var > 0.0 && var > filter->max_var) {
+    DEBUG_LOG("filter dispersion too large disp=%.9f max=%.9f",
+              sqrt(var), sqrt(filter->max_var));
+    return 0;
+  }
+
+  prev_avg_var = filter->avg_var;
+
+  /* Update the exponential moving average of the variance */
+  if (filter->avg_var_n > 50) {
+    filter->avg_var += dof / (dof + 50.0) * (var - filter->avg_var);
+  } else {
+    filter->avg_var = (filter->avg_var * filter->avg_var_n + var * dof) /
+      (dof + filter->avg_var_n);
+    if (filter->avg_var_n == 0)
+      prev_avg_var = filter->avg_var;
+    filter->avg_var_n += dof;
+  }
+
+  /* Use the long-term average of variance instead of the estimated value
+     unless it is significantly smaller in order to reduce the noise in
+     sourcestats weights */
+  if (var * dof / RGR_GetChi2Coef(dof) < prev_avg_var)
+    disp = sqrt(filter->avg_var) * disp / sqrt(var);
+
+  mean_peer_dispersion = mean_root_dispersion = mean_peer_delay = mean_root_delay = 0.0;
+
+  for (i = 0; i < n; i++) {
+    sample = &filter->samples[filter->selected[i]];
+
+    mean_peer_dispersion += sample->peer_dispersion;
+    mean_root_dispersion += sample->root_dispersion;
+    mean_peer_delay += sample->peer_delay;
+    mean_root_delay += sample->root_delay;
+  }
+
+  mean_peer_dispersion /= n;
+  mean_root_dispersion /= n;
+  mean_peer_delay /= n;
+  mean_root_delay /= n;
+
+  UTI_AddDoubleToTimespec(&last_sample->time, mean_x, &result->time);
+  result->offset = mean_y;
+  result->peer_dispersion = MAX(disp, mean_peer_dispersion);
+  result->root_dispersion = MAX(disp, mean_root_dispersion);
+  result->peer_delay = mean_peer_delay;
+  result->root_delay = mean_root_delay;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetFilteredSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  int n;
+
+  n = select_samples(filter);
+
+  DEBUG_LOG("selected %d from %d samples", n, filter->used);
+
+  if (n < 1)
+    return 0;
+
+  if (!combine_selected_samples(filter, n, sample))
+    return 0;
+
+  drop_samples(filter, 1);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+get_first_last(SPF_Instance filter, int *first, int *last)
+{
+  if (filter->last < 0)
+    return 0;
+
+  /* Always slew the last sample as it may be returned even if no new
+     samples were accumulated */
+  if (filter->used > 0) {
+    *first = 0;
+    *last = filter->used - 1;
+  } else {
+    *first = *last = filter->last;
+  }
+
+  return 1;
+}
+
+
+/* ================================================== */
+
+void
+SPF_SlewSamples(SPF_Instance filter, struct timespec *when, double dfreq, double doffset)
+{
+  int i, first, last;
+  double delta_time;
+
+  if (!get_first_last(filter, &first, &last))
+    return;
+
+  for (i = first; i <= last; i++) {
+    UTI_AdjustTimespec(&filter->samples[i].time, when, &filter->samples[i].time,
+                       &delta_time, dfreq, doffset);
+    filter->samples[i].offset -= delta_time;
+  }
+}
+
+/* ================================================== */
+
+void
+SPF_CorrectOffset(SPF_Instance filter, double doffset)
+{
+  int i, first, last;
+
+  if (!get_first_last(filter, &first, &last))
+    return;
+
+  for (i = first; i <= last; i++)
+    filter->samples[i].offset -= doffset;
+}
+
+/* ================================================== */
+
+void
+SPF_AddDispersion(SPF_Instance filter, double dispersion)
+{
+  int i;
+
+  for (i = 0; i < filter->used; i++) {
+    filter->samples[i].peer_dispersion += dispersion;
+    filter->samples[i].root_dispersion += dispersion;
+  }
+}
diff --git a/samplefilt.h b/samplefilt.h
new file mode 100644
index 0000000..8d72b85
--- /dev/null
+++ b/samplefilt.h
@@ -0,0 +1,51 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for sample filter.
+
+  */
+
+#ifndef GOT_SAMPLEFILT_H
+#define GOT_SAMPLEFILT_H
+
+#include "ntp.h"
+
+typedef struct SPF_Instance_Record *SPF_Instance;
+
+extern SPF_Instance SPF_CreateInstance(int min_samples, int max_samples,
+                                       double max_dispersion, double combine_ratio);
+extern void SPF_DestroyInstance(SPF_Instance filter);
+
+extern int SPF_AccumulateSample(SPF_Instance filter, NTP_Sample *sample);
+extern int SPF_GetLastSample(SPF_Instance filter, NTP_Sample *sample);
+extern int SPF_GetNumberOfSamples(SPF_Instance filter);
+extern int SPF_GetMaxSamples(SPF_Instance filter);
+extern double SPF_GetAvgSampleDispersion(SPF_Instance filter);
+extern void SPF_DropSamples(SPF_Instance filter);
+extern int SPF_GetFilteredSample(SPF_Instance filter, NTP_Sample *sample);
+extern void SPF_SlewSamples(SPF_Instance filter, struct timespec *when,
+                            double dfreq, double doffset);
+extern void SPF_CorrectOffset(SPF_Instance filter, double doffset);
+extern void SPF_AddDispersion(SPF_Instance filter, double dispersion);
+
+#endif
diff --git a/sched.c b/sched.c
new file mode 100644
index 0000000..1f5ebe4
--- /dev/null
+++ b/sched.c
@@ -0,0 +1,852 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2013-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains the scheduling loop and the timeout queue.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "sched.h"
+#include "memory.h"
+#include "util.h"
+#include "local.h"
+#include "logging.h"
+
+/* ================================================== */
+
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* ================================================== */
+
+/* One more than the highest file descriptor that is registered */
+static unsigned int one_highest_fd;
+
+#ifndef FD_SETSIZE
+/* If FD_SETSIZE is not defined, assume that fd_set is implemented
+   as a fixed size array of bits, possibly embedded inside a record */
+#define FD_SETSIZE (sizeof(fd_set) * 8)
+#endif
+
+typedef struct {
+  SCH_FileHandler       handler;
+  SCH_ArbitraryArgument arg;
+  int                   events;
+} FileHandlerEntry;
+
+static ARR_Instance file_handlers;
+
+/* Timestamp when last select() returned */
+static struct timespec last_select_ts, last_select_ts_raw;
+static double last_select_ts_err;
+
+#define TS_MONO_PRECISION_NS 10000000U
+
+/* Monotonic low-precision timestamp measuring interval since the start */
+static double last_select_ts_mono;
+static uint32_t last_select_ts_mono_ns;
+
+/* ================================================== */
+
+/* Variables to handler the timer queue */
+
+typedef struct _TimerQueueEntry
+{
+  struct _TimerQueueEntry *next; /* Forward and back links in the list */
+  struct _TimerQueueEntry *prev;
+  struct timespec ts;           /* Local system time at which the
+                                   timeout is to expire.  Clearly this
+                                   must be in terms of what the
+                                   operating system thinks of as
+                                   system time, because it will be an
+                                   argument to select().  Therefore,
+                                   any fudges etc that our local time
+                                   driver module would apply to time
+                                   that we pass to clients etc doesn't
+                                   apply to this. */
+  SCH_TimeoutID id;             /* ID to allow client to delete
+                                   timeout */
+  SCH_TimeoutClass class;       /* The class that the epoch is in */
+  SCH_TimeoutHandler handler;   /* The handler routine to use */
+  SCH_ArbitraryArgument arg;    /* The argument to pass to the handler */
+
+} TimerQueueEntry;
+
+/* The timer queue.  We only use the next and prev entries of this
+   record, these chain to the real entries. */
+static TimerQueueEntry timer_queue;
+static unsigned long n_timer_queue_entries;
+static SCH_TimeoutID next_tqe_id;
+
+/* Pointer to head of free list */
+static TimerQueueEntry *tqe_free_list = NULL;
+
+/* Timestamp when was last timeout dispatched for each class */
+static struct timespec last_class_dispatch[SCH_NumberOfClasses];
+
+/* ================================================== */
+
+/* Flag terminating the main loop, which can be set from a signal handler */
+static volatile int need_to_exit;
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything);
+
+/* ================================================== */
+
+void
+SCH_Initialise(void)
+{
+  file_handlers = ARR_CreateInstance(sizeof (FileHandlerEntry));
+
+  n_timer_queue_entries = 0;
+  next_tqe_id = 0;
+
+  timer_queue.next = &timer_queue;
+  timer_queue.prev = &timer_queue;
+
+  need_to_exit = 0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+
+  LCL_ReadRawTime(&last_select_ts_raw);
+  last_select_ts = last_select_ts_raw;
+  last_select_ts_mono = 0.0;
+  last_select_ts_mono_ns = 0;
+
+  initialised = 1;
+}
+
+
+/* ================================================== */
+
+void
+SCH_Finalise(void) {
+  ARR_DestroyInstance(file_handlers);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void
+SCH_AddFileHandler
+(int fd, int events, SCH_FileHandler handler, SCH_ArbitraryArgument arg)
+{
+  FileHandlerEntry *ptr;
+
+  assert(initialised);
+  assert(events);
+  assert(fd >= 0);
+  
+  if (fd >= FD_SETSIZE)
+    LOG_FATAL("Too many file descriptors");
+
+  /* Resize the array if the descriptor is highest so far */
+  while (ARR_GetSize(file_handlers) <= fd) {
+    ptr = ARR_GetNewElement(file_handlers);
+    ptr->handler = NULL;
+    ptr->arg = NULL;
+    ptr->events = 0;
+  }
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  /* Don't want to allow the same fd to register a handler more than
+     once without deleting a previous association - this suggests
+     a bug somewhere else in the program. */
+  assert(!ptr->handler);
+
+  ptr->handler = handler;
+  ptr->arg = arg;
+  ptr->events = events;
+
+  if (one_highest_fd < fd + 1)
+    one_highest_fd = fd + 1;
+}
+
+
+/* ================================================== */
+
+void
+SCH_RemoveFileHandler(int fd)
+{
+  FileHandlerEntry *ptr;
+
+  assert(initialised);
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  /* Check that a handler was registered for the fd in question */
+  assert(ptr->handler);
+
+  ptr->handler = NULL;
+  ptr->arg = NULL;
+  ptr->events = 0;
+
+  /* Find new highest file descriptor */
+  while (one_highest_fd > 0) {
+    ptr = ARR_GetElement(file_handlers, one_highest_fd - 1);
+    if (ptr->handler)
+      break;
+    one_highest_fd--;
+  }
+}
+
+/* ================================================== */
+
+void
+SCH_SetFileHandlerEvent(int fd, int event, int enable)
+{
+  FileHandlerEntry *ptr;
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  if (enable)
+    ptr->events |= event;
+  else
+    ptr->events &= ~event;
+}
+
+/* ================================================== */
+
+void
+SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw)
+{
+  if (cooked) {
+    *cooked = last_select_ts;
+    if (err)
+      *err = last_select_ts_err;
+  }
+  if (raw)
+    *raw = last_select_ts_raw;
+}
+
+/* ================================================== */
+
+double
+SCH_GetLastEventMonoTime(void)
+{
+  return last_select_ts_mono;
+}
+
+/* ================================================== */
+
+#define TQE_ALLOC_QUANTUM 32
+
+static TimerQueueEntry *
+allocate_tqe(void)
+{
+  TimerQueueEntry *new_block;
+  TimerQueueEntry *result;
+  int i;
+  if (tqe_free_list == NULL) {
+    new_block = MallocArray(TimerQueueEntry, TQE_ALLOC_QUANTUM);
+    for (i=1; i<TQE_ALLOC_QUANTUM; i++) {
+      new_block[i].next = &(new_block[i-1]);
+    }
+    new_block[0].next = NULL;
+    tqe_free_list = &(new_block[TQE_ALLOC_QUANTUM - 1]);
+  }
+
+  result = tqe_free_list;
+  tqe_free_list = tqe_free_list->next;
+  return result;
+}
+
+/* ================================================== */
+
+static void
+release_tqe(TimerQueueEntry *node)
+{
+  node->next = tqe_free_list;
+  tqe_free_list = node;
+}
+
+/* ================================================== */
+
+static SCH_TimeoutID
+get_new_tqe_id(void)
+{
+  TimerQueueEntry *ptr;
+
+try_again:
+  next_tqe_id++;
+  if (!next_tqe_id)
+    goto try_again;
+
+  /* Make sure the ID isn't already used */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next)
+    if (ptr->id == next_tqe_id)
+      goto try_again;
+
+  return next_tqe_id;
+}
+
+/* ================================================== */
+
+SCH_TimeoutID
+SCH_AddTimeout(struct timespec *ts, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  TimerQueueEntry *new_tqe;
+  TimerQueueEntry *ptr;
+
+  assert(initialised);
+
+  new_tqe = allocate_tqe();
+
+  new_tqe->id = get_new_tqe_id();
+  new_tqe->handler = handler;
+  new_tqe->arg = arg;
+  new_tqe->ts = *ts;
+  new_tqe->class = SCH_ReservedTimeoutValue;
+
+  /* Now work out where to insert the new entry in the list */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    if (UTI_CompareTimespecs(&new_tqe->ts, &ptr->ts) == -1) {
+      /* If the new entry comes before the current pointer location in
+         the list, we want to insert the new entry just before ptr. */
+      break;
+    }
+  }
+
+  /* At this stage, we want to insert the new entry immediately before
+     the entry identified by 'ptr' */
+
+  new_tqe->next = ptr;
+  new_tqe->prev = ptr->prev;
+  ptr->prev->next = new_tqe;
+  ptr->prev = new_tqe;
+
+  n_timer_queue_entries++;
+
+  return new_tqe->id;
+}
+
+/* ================================================== */
+/* This queues a timeout to elapse at a given delta time relative to
+   the current (raw) time */
+
+SCH_TimeoutID
+SCH_AddTimeoutByDelay(double delay, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  struct timespec now, then;
+
+  assert(initialised);
+  assert(delay >= 0.0);
+
+  LCL_ReadRawTime(&now);
+  UTI_AddDoubleToTimespec(&now, delay, &then);
+  if (UTI_CompareTimespecs(&now, &then) > 0) {
+    LOG_FATAL("Timeout overflow");
+  }
+
+  return SCH_AddTimeout(&then, handler, arg);
+
+}
+
+/* ================================================== */
+
+SCH_TimeoutID
+SCH_AddTimeoutInClass(double min_delay, double separation, double randomness,
+                      SCH_TimeoutClass class,
+                      SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  TimerQueueEntry *new_tqe;
+  TimerQueueEntry *ptr;
+  struct timespec now;
+  double diff, r;
+  double new_min_delay;
+
+  assert(initialised);
+  assert(min_delay >= 0.0);
+  assert(class < SCH_NumberOfClasses);
+
+  if (randomness > 0.0) {
+    uint32_t rnd;
+
+    UTI_GetRandomBytes(&rnd, sizeof (rnd));
+    r = rnd * (randomness / (uint32_t)-1) + 1.0;
+    min_delay *= r;
+    separation *= r;
+  }
+  
+  LCL_ReadRawTime(&now);
+  new_min_delay = min_delay;
+
+  /* Check the separation from the last dispatched timeout */
+  diff = UTI_DiffTimespecsToDouble(&now, &last_class_dispatch[class]);
+  if (diff < separation && diff >= 0.0 && diff + new_min_delay < separation) {
+    new_min_delay = separation - diff;
+  }
+
+  /* Scan through list for entries in the same class and increase min_delay
+     if necessary to keep at least the separation away */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    if (ptr->class == class) {
+      diff = UTI_DiffTimespecsToDouble(&ptr->ts, &now);
+      if (new_min_delay > diff) {
+        if (new_min_delay - diff < separation) {
+          new_min_delay = diff + separation;
+        }
+      } else {
+        if (diff - new_min_delay < separation) {
+          new_min_delay = diff + separation;
+        }
+      }
+    }
+  }
+
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    diff = UTI_DiffTimespecsToDouble(&ptr->ts, &now);
+    if (diff > new_min_delay) {
+      break;
+    }
+  }
+
+  /* We have located the insertion point */
+  new_tqe = allocate_tqe();
+
+  new_tqe->id = get_new_tqe_id();
+  new_tqe->handler = handler;
+  new_tqe->arg = arg;
+  UTI_AddDoubleToTimespec(&now, new_min_delay, &new_tqe->ts);
+  new_tqe->class = class;
+
+  new_tqe->next = ptr;
+  new_tqe->prev = ptr->prev;
+  ptr->prev->next = new_tqe;
+  ptr->prev = new_tqe;
+  n_timer_queue_entries++;
+
+  return new_tqe->id;
+}
+
+/* ================================================== */
+
+void
+SCH_RemoveTimeout(SCH_TimeoutID id)
+{
+  TimerQueueEntry *ptr;
+
+  assert(initialised);
+
+  if (!id)
+    return;
+
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+
+    if (ptr->id == id) {
+      /* Found the required entry */
+      
+      /* Unlink from the queue */
+      ptr->next->prev = ptr->prev;
+      ptr->prev->next = ptr->next;
+      
+      /* Decrement entry count */
+      --n_timer_queue_entries;
+      
+      /* Release memory back to the operating system */
+      release_tqe(ptr);
+
+      return;
+    }
+  }
+
+  /* Catch calls with invalid non-zero ID */
+  assert(0);
+}
+
+/* ================================================== */
+/* Try to dispatch any timeouts that have already gone by, and
+   keep going until all are done.  (The earlier ones may take so
+   long to do that the later ones come around by the time they are
+   completed). */
+
+static void
+dispatch_timeouts(struct timespec *now) {
+  unsigned long n_done, n_entries_on_start;
+  TimerQueueEntry *ptr;
+  SCH_TimeoutHandler handler;
+  SCH_ArbitraryArgument arg;
+
+  n_entries_on_start = n_timer_queue_entries;
+  n_done = 0;
+
+  do {
+    LCL_ReadRawTime(now);
+
+    if (!(n_timer_queue_entries > 0 &&
+          UTI_CompareTimespecs(now, &timer_queue.next->ts) >= 0)) {
+      break;
+    }
+
+    ptr = timer_queue.next;
+
+    last_class_dispatch[ptr->class] = *now;
+
+    handler = ptr->handler;
+    arg = ptr->arg;
+
+    SCH_RemoveTimeout(ptr->id);
+
+    /* Dispatch the handler */
+    (handler)(arg);
+
+    /* Increment count of timeouts handled */
+    ++n_done;
+
+    /* If the number of dispatched timeouts is significantly larger than the
+       length of the queue on start and now, assume there is a bug causing
+       an infinite loop by constantly adding a timeout with a zero or negative
+       delay.  Check the actual rate of timeouts to avoid false positives in
+       case the execution slowed down so much (e.g. due to memory thrashing)
+       that it repeatedly takes more time to handle the timeout than is its
+       delay.  This is a safety mechanism intended to stop a full-speed flood
+       of NTP requests due to a bug in the NTP polling. */
+
+    if (n_done > 20 &&
+        n_done > 4 * MAX(n_timer_queue_entries, n_entries_on_start) &&
+        fabs(UTI_DiffTimespecsToDouble(now, &last_select_ts_raw)) / n_done < 0.01)
+      LOG_FATAL("Possible infinite loop in scheduling");
+
+  } while (!need_to_exit);
+}
+
+/* ================================================== */
+
+/* nfd is the number of bits set in all fd_sets */
+
+static void
+dispatch_filehandlers(int nfd, fd_set *read_fds, fd_set *write_fds, fd_set *except_fds)
+{
+  FileHandlerEntry *ptr;
+  int fd;
+  
+  for (fd = 0; nfd && fd < one_highest_fd; fd++) {
+    if (except_fds && FD_ISSET(fd, except_fds)) {
+      /* This descriptor has an exception, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_EXCEPTION, ptr->arg);
+      nfd--;
+
+      /* Don't try to read from it now */
+      if (read_fds && FD_ISSET(fd, read_fds)) {
+        FD_CLR(fd, read_fds);
+        nfd--;
+      }
+    }
+
+    if (read_fds && FD_ISSET(fd, read_fds)) {
+      /* This descriptor can be read from, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_INPUT, ptr->arg);
+      nfd--;
+    }
+
+    if (write_fds && FD_ISSET(fd, write_fds)) {
+      /* This descriptor can be written to, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_OUTPUT, ptr->arg);
+      nfd--;
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything)
+{
+  TimerQueueEntry *ptr;
+  double delta;
+  int i;
+
+  if (change_type != LCL_ChangeAdjust) {
+    /* Make sure this handler is invoked first in order to not shift new timers
+       added from other handlers */
+    assert(LCL_IsFirstParameterChangeHandler(handle_slew));
+
+    /* If a step change occurs, just shift all raw time stamps by the offset */
+    
+    for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+      UTI_AddDoubleToTimespec(&ptr->ts, -doffset, &ptr->ts);
+    }
+
+    for (i = 0; i < SCH_NumberOfClasses; i++) {
+      UTI_AddDoubleToTimespec(&last_class_dispatch[i], -doffset, &last_class_dispatch[i]);
+    }
+
+    UTI_AddDoubleToTimespec(&last_select_ts_raw, -doffset, &last_select_ts_raw);
+  }
+
+  UTI_AdjustTimespec(&last_select_ts, cooked, &last_select_ts, &delta, dfreq, doffset);
+}
+
+/* ================================================== */
+
+static void
+fill_fd_sets(fd_set **read_fds, fd_set **write_fds, fd_set **except_fds)
+{
+  FileHandlerEntry *handlers;
+  fd_set *rd, *wr, *ex;
+  int i, n, events;
+
+  n = ARR_GetSize(file_handlers);
+  handlers = ARR_GetElements(file_handlers);
+  rd = wr = ex = NULL;
+
+  for (i = 0; i < n; i++) {
+    events = handlers[i].events;
+
+    if (!events)
+      continue;
+
+    if (events & SCH_FILE_INPUT) {
+      if (!rd) {
+        rd = *read_fds;
+        FD_ZERO(rd);
+      }
+      FD_SET(i, rd);
+    }
+
+    if (events & SCH_FILE_OUTPUT) {
+      if (!wr) {
+        wr = *write_fds;
+        FD_ZERO(wr);
+      }
+      FD_SET(i, wr);
+    }
+
+    if (events & SCH_FILE_EXCEPTION) {
+      if (!ex) {
+        ex = *except_fds;
+        FD_ZERO(ex);
+      }
+      FD_SET(i, ex);
+    }
+  }
+
+  if (!rd)
+    *read_fds = NULL;
+  if (!wr)
+    *write_fds = NULL;
+  if (!ex)
+    *except_fds = NULL;
+}
+
+/* ================================================== */
+
+#define JUMP_DETECT_THRESHOLD 10
+
+static int
+check_current_time(struct timespec *prev_raw, struct timespec *raw, int timeout,
+                   struct timeval *orig_select_tv,
+                   struct timeval *rem_select_tv)
+{
+  struct timespec elapsed_min, elapsed_max, orig_select_ts, rem_select_ts;
+  double step, elapsed;
+
+  UTI_TimevalToTimespec(orig_select_tv, &orig_select_ts);
+
+  /* Get an estimate of the time spent waiting in the select() call. On some
+     systems (e.g. Linux) the timeout timeval is modified to return the
+     remaining time, use that information. */
+  if (timeout) {
+    elapsed_max = elapsed_min = orig_select_ts;
+  } else if (rem_select_tv && rem_select_tv->tv_sec >= 0 &&
+             rem_select_tv->tv_sec <= orig_select_tv->tv_sec &&
+             (rem_select_tv->tv_sec != orig_select_tv->tv_sec ||
+              rem_select_tv->tv_usec != orig_select_tv->tv_usec)) {
+    UTI_TimevalToTimespec(rem_select_tv, &rem_select_ts);
+    UTI_DiffTimespecs(&elapsed_min, &orig_select_ts, &rem_select_ts);
+    elapsed_max = elapsed_min;
+  } else {
+    if (rem_select_tv)
+      elapsed_max = orig_select_ts;
+    else
+      UTI_DiffTimespecs(&elapsed_max, raw, prev_raw);
+    UTI_ZeroTimespec(&elapsed_min);
+  }
+
+  if (last_select_ts_raw.tv_sec + elapsed_min.tv_sec >
+      raw->tv_sec + JUMP_DETECT_THRESHOLD) {
+    LOG(LOGS_WARN, "Backward time jump detected!");
+  } else if (prev_raw->tv_sec + elapsed_max.tv_sec + JUMP_DETECT_THRESHOLD <
+             raw->tv_sec) {
+    LOG(LOGS_WARN, "Forward time jump detected!");
+  } else {
+    return 1;
+  }
+
+  step = UTI_DiffTimespecsToDouble(&last_select_ts_raw, raw);
+  elapsed = UTI_TimespecToDouble(&elapsed_min);
+  step += elapsed;
+
+  /* Cooked time may no longer be valid after dispatching the handlers */
+  LCL_NotifyExternalTimeStep(raw, raw, step, fabs(step));
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+update_monotonic_time(struct timespec *now, struct timespec *before)
+{
+  struct timespec diff;
+
+  /* Avoid frequent floating-point operations and handle small
+     increments to a large value */
+
+  UTI_DiffTimespecs(&diff, now, before);
+  if (diff.tv_sec == 0) {
+    last_select_ts_mono_ns += diff.tv_nsec;
+  } else {
+    last_select_ts_mono += fabs(UTI_TimespecToDouble(&diff) +
+                                last_select_ts_mono_ns / 1.0e9);
+    last_select_ts_mono_ns = 0;
+  }
+
+  if (last_select_ts_mono_ns > TS_MONO_PRECISION_NS) {
+    last_select_ts_mono += last_select_ts_mono_ns / 1.0e9;
+    last_select_ts_mono_ns = 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCH_MainLoop(void)
+{
+  fd_set read_fds, write_fds, except_fds;
+  fd_set *p_read_fds, *p_write_fds, *p_except_fds;
+  int status, errsv;
+  struct timeval tv, saved_tv, *ptv;
+  struct timespec ts, now, saved_now, cooked;
+  double err;
+
+  assert(initialised);
+
+  while (!need_to_exit) {
+    /* Dispatch timeouts and fill now with current raw time */
+    dispatch_timeouts(&now);
+    saved_now = now;
+    
+    /* The timeout handlers may request quit */
+    if (need_to_exit)
+      break;
+
+    /* Check whether there is a timeout and set it up */
+    if (n_timer_queue_entries > 0) {
+      UTI_DiffTimespecs(&ts, &timer_queue.next->ts, &now);
+      assert(ts.tv_sec > 0 || ts.tv_nsec > 0);
+
+      UTI_TimespecToTimeval(&ts, &tv);
+      ptv = &tv;
+      saved_tv = tv;
+    } else {
+      ptv = NULL;
+      saved_tv.tv_sec = saved_tv.tv_usec = 0;
+    }
+
+    p_read_fds = &read_fds;
+    p_write_fds = &write_fds;
+    p_except_fds = &except_fds;
+    fill_fd_sets(&p_read_fds, &p_write_fds, &p_except_fds);
+
+    /* if there are no file descriptors being waited on and no
+       timeout set, this is clearly ridiculous, so stop the run */
+    if (!ptv && !p_read_fds && !p_write_fds)
+      LOG_FATAL("Nothing to do");
+
+    status = select(one_highest_fd, p_read_fds, p_write_fds, p_except_fds, ptv);
+    errsv = errno;
+
+    LCL_ReadRawTime(&now);
+    LCL_CookTime(&now, &cooked, &err);
+
+    update_monotonic_time(&now, &last_select_ts_raw);
+
+    /* Check if the time didn't jump unexpectedly */
+    if (!check_current_time(&saved_now, &now, status == 0, &saved_tv, ptv)) {
+      /* Cook the time again after handling the step */
+      LCL_CookTime(&now, &cooked, &err);
+    }
+
+    last_select_ts_raw = now;
+    last_select_ts = cooked;
+    last_select_ts_err = err;
+
+    if (status < 0) {
+      if (!need_to_exit && errsv != EINTR) {
+        LOG_FATAL("select() failed : %s", strerror(errsv));
+      }
+    } else if (status > 0) {
+      /* A file descriptor is ready for input or output */
+      dispatch_filehandlers(status, p_read_fds, p_write_fds, p_except_fds);
+    } else {
+      /* No descriptors readable, timeout must have elapsed.
+       Therefore, tv must be non-null */
+      assert(ptv);
+
+      /* There's nothing to do here, since the timeouts
+         will be dispatched at the top of the next loop
+         cycle */
+
+    }
+  }         
+}
+
+/* ================================================== */
+
+void
+SCH_QuitProgram(void)
+{
+  need_to_exit = 1;
+}
+
+/* ================================================== */
+
diff --git a/sched.h b/sched.h
new file mode 100644
index 0000000..f1f4eb9
--- /dev/null
+++ b/sched.h
@@ -0,0 +1,92 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Exported header file for sched.c
+  */
+
+#ifndef GOT_SCHED_H
+#define GOT_SCHED_H
+
+#include "sysincl.h"
+
+/* Type for timeout IDs, valid IDs are always greater than zero */
+typedef unsigned int SCH_TimeoutID;
+
+typedef enum {
+  SCH_ReservedTimeoutValue = 0,
+  SCH_NtpClientClass,
+  SCH_NtpPeerClass,
+  SCH_NtpBroadcastClass,
+  SCH_NumberOfClasses /* needs to be last */
+} SCH_TimeoutClass;
+
+typedef void* SCH_ArbitraryArgument;
+typedef void (*SCH_FileHandler)(int fd, int event, SCH_ArbitraryArgument);
+typedef void (*SCH_TimeoutHandler)(SCH_ArbitraryArgument);
+
+/* Exported functions */
+
+/* Initialisation function for the module */
+extern void SCH_Initialise(void);
+
+/* Finalisation function for the module */
+extern void SCH_Finalise(void);
+
+/* File events */
+#define SCH_FILE_INPUT 1
+#define SCH_FILE_OUTPUT 2
+#define SCH_FILE_EXCEPTION 4
+
+/* Register a handler for when select goes true on a file descriptor */
+extern void SCH_AddFileHandler(int fd, int events, SCH_FileHandler handler, SCH_ArbitraryArgument arg);
+extern void SCH_RemoveFileHandler(int fd);
+extern void SCH_SetFileHandlerEvent(int fd, int event, int enable);
+
+/* Get the time stamp taken after a file descriptor became ready or a timeout expired */
+extern void SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw);
+
+/* Get a low-precision monotonic timestamp (starting at 0.0) */
+extern double SCH_GetLastEventMonoTime(void);
+
+/* This queues a timeout to elapse at a given (raw) local time */
+extern SCH_TimeoutID SCH_AddTimeout(struct timespec *ts, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg);
+
+/* This queues a timeout to elapse at a given delta time relative to the current (raw) time */
+extern SCH_TimeoutID SCH_AddTimeoutByDelay(double delay, SCH_TimeoutHandler, SCH_ArbitraryArgument);
+
+/* This queues a timeout in a particular class, ensuring that the
+   expiry time is at least a given separation away from any other
+   timeout in the same class, given randomness is added to the delay
+   and separation */
+extern SCH_TimeoutID SCH_AddTimeoutInClass(double min_delay, double separation, double randomness,
+                                           SCH_TimeoutClass class,
+                                           SCH_TimeoutHandler handler, SCH_ArbitraryArgument);
+
+/* The next one probably ought to return a status code */
+extern void SCH_RemoveTimeout(SCH_TimeoutID);
+
+extern void SCH_MainLoop(void);
+
+extern void SCH_QuitProgram(void);
+
+#endif /* GOT_SCHED_H */
diff --git a/siv.h b/siv.h
new file mode 100644
index 0000000..e303d34
--- /dev/null
+++ b/siv.h
@@ -0,0 +1,70 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for Synthetic Initialization Vector (SIV) ciphers.
+
+  */
+
+#ifndef GOT_SIV_H
+#define GOT_SIV_H
+
+/* Maximum key length of all supported SIVs */
+#define SIV_MAX_KEY_LENGTH 32
+
+/* Maximum difference between lengths of ciphertext and plaintext */
+#define SIV_MAX_TAG_LENGTH 16
+
+/* Identifiers of SIV algorithms following the IANA AEAD registry */
+typedef enum {
+  AEAD_AES_SIV_CMAC_256 = 15,
+  AEAD_AES_SIV_CMAC_384 = 16,
+  AEAD_AES_SIV_CMAC_512 = 17,
+  AEAD_AES_128_GCM_SIV = 30,
+  AEAD_AES_256_GCM_SIV = 31,
+} SIV_Algorithm;
+
+typedef struct SIV_Instance_Record *SIV_Instance;
+
+extern SIV_Instance SIV_CreateInstance(SIV_Algorithm algorithm);
+
+extern void SIV_DestroyInstance(SIV_Instance instance);
+
+extern int SIV_GetKeyLength(SIV_Algorithm algorithm);
+
+extern int SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length);
+
+extern int SIV_GetTagLength(SIV_Instance instance);
+
+extern int SIV_Encrypt(SIV_Instance instance,
+                       const unsigned char *nonce, int nonce_length,
+                       const void *assoc, int assoc_length,
+                       const void *plaintext, int plaintext_length,
+                       unsigned char *ciphertext, int ciphertext_length);
+
+extern int SIV_Decrypt(SIV_Instance instance,
+                       const unsigned char *nonce, int nonce_length,
+                       const void *assoc, int assoc_length,
+                       const unsigned char *ciphertext, int ciphertext_length,
+                       void *plaintext, int plaintext_length);
+
+#endif
diff --git a/siv_gnutls.c b/siv_gnutls.c
new file mode 100644
index 0000000..aba2bab
--- /dev/null
+++ b/siv_gnutls.c
@@ -0,0 +1,271 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  SIV ciphers using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "logging.h"
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+  gnutls_cipher_algorithm_t algorithm;
+  gnutls_aead_cipher_hd_t cipher;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  DEBUG_LOG("Initialised");
+  gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  assert(gnutls_initialised);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_cipher_algorithm_t
+get_cipher_algorithm(SIV_Algorithm algorithm)
+{
+  switch (algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      return GNUTLS_CIPHER_AES_128_SIV;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+  gnutls_cipher_algorithm_t calgo;
+  SIV_Instance instance;
+
+  calgo = get_cipher_algorithm(algorithm);
+  if (calgo == 0)
+    return NULL;
+
+  if (instance_counter == 0)
+    init_gnutls();
+
+  /* Check if the cipher is actually supported */
+  if (gnutls_cipher_get_tag_size(calgo) == 0) {
+    if (instance_counter == 0)
+      deinit_gnutls();
+    return NULL;
+  }
+
+  instance = MallocNew(struct SIV_Instance_Record);
+  instance->algorithm = calgo;
+  instance->cipher = NULL;
+
+  instance_counter++;
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+  if (instance->cipher)
+    gnutls_aead_cipher_deinit(instance->cipher);
+  Free(instance);
+
+  instance_counter--;
+  if (instance_counter == 0)
+    deinit_gnutls();
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+  gnutls_cipher_algorithm_t calgo = get_cipher_algorithm(algorithm);
+  int len;
+
+  if (calgo == 0)
+    return 0;
+
+  len = gnutls_cipher_get_key_size(calgo);
+
+  if (len < 1 || len > SIV_MAX_KEY_LENGTH)
+    LOG_FATAL("Invalid key length");
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+  gnutls_aead_cipher_hd_t cipher;
+  gnutls_datum_t datum;
+  int r;
+
+  if (length <= 0 || length != gnutls_cipher_get_key_size(instance->algorithm))
+    return 0;
+
+  datum.data = (unsigned char *)key;
+  datum.size = length;
+
+#ifdef HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+  if (instance->cipher) {
+    r = gnutls_aead_cipher_set_key(instance->cipher, &datum);
+    if (r < 0) {
+      DEBUG_LOG("Could not set cipher key : %s", gnutls_strerror(r));
+      return 0;
+    }
+
+    return 1;
+  }
+#endif
+
+  /* Initialise a new cipher with the provided key */
+  r = gnutls_aead_cipher_init(&cipher, instance->algorithm, &datum);
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "cipher", gnutls_strerror(r));
+    return 0;
+  }
+
+  /* Destroy the previous cipher (if its key could not be changed directly) */
+  if (instance->cipher)
+    gnutls_aead_cipher_deinit(instance->cipher);
+
+  instance->cipher = cipher;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+  int len;
+
+  len = gnutls_cipher_get_tag_size(instance->algorithm);
+
+  if (len < 1 || len > SIV_MAX_TAG_LENGTH)
+    LOG_FATAL("Invalid tag length");
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+SIV_Encrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const void *plaintext, int plaintext_length,
+            unsigned char *ciphertext, int ciphertext_length)
+{
+  size_t clen = ciphertext_length;
+
+  if (!instance->cipher)
+    return 0;
+
+  if (nonce_length < 1 || assoc_length < 0 ||
+      plaintext_length < 0 || ciphertext_length < 0)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (gnutls_aead_cipher_encrypt(instance->cipher,
+                                 nonce, nonce_length, assoc, assoc_length, 0,
+                                 plaintext, plaintext_length, ciphertext, &clen) < 0)
+    return 0;
+
+  if (clen != ciphertext_length)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_Decrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const unsigned char *ciphertext, int ciphertext_length,
+            void *plaintext, int plaintext_length)
+{
+  size_t plen = plaintext_length;
+
+  if (!instance->cipher)
+    return 0;
+
+  if (nonce_length < 1 || assoc_length < 0 ||
+      plaintext_length < 0 || ciphertext_length < 0)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (gnutls_aead_cipher_decrypt(instance->cipher,
+                                 nonce, nonce_length, assoc, assoc_length, 0,
+                                 ciphertext, ciphertext_length, plaintext, &plen) < 0)
+    return 0;
+
+  if (plen != plaintext_length)
+    return 0;
+
+  return 1;
+}
diff --git a/siv_nettle.c b/siv_nettle.c
new file mode 100644
index 0000000..d8f8b23
--- /dev/null
+++ b/siv_nettle.c
@@ -0,0 +1,156 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  SIV ciphers using the Nettle library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#ifdef HAVE_NETTLE_SIV_CMAC
+#include <nettle/siv-cmac.h>
+#else
+#include "siv_nettle_int.c"
+#endif
+
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+  struct siv_cmac_aes128_ctx siv;
+  int key_set;
+};
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+  SIV_Instance instance;
+
+  if (algorithm != AEAD_AES_SIV_CMAC_256)
+    return NULL;
+
+  instance = MallocNew(struct SIV_Instance_Record);
+  instance->key_set = 0;
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+  Free(instance);
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+  assert(32 <= SIV_MAX_KEY_LENGTH);
+
+  if (algorithm == AEAD_AES_SIV_CMAC_256)
+    return 32;
+  return 0;
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+  if (length != 32)
+    return 0;
+
+  siv_cmac_aes128_set_key(&instance->siv, key);
+
+  instance->key_set = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+  assert(SIV_DIGEST_SIZE <= SIV_MAX_TAG_LENGTH);
+
+  return SIV_DIGEST_SIZE;
+}
+
+/* ================================================== */
+
+int
+SIV_Encrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const void *plaintext, int plaintext_length,
+            unsigned char *ciphertext, int ciphertext_length)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < SIV_MIN_NONCE_SIZE || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_DIGEST_SIZE != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  siv_cmac_aes128_encrypt_message(&instance->siv, nonce_length, nonce,
+                                  assoc_length, assoc,
+                                  ciphertext_length, ciphertext, plaintext);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_Decrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const unsigned char *ciphertext, int ciphertext_length,
+            void *plaintext, int plaintext_length)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < SIV_MIN_NONCE_SIZE || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_DIGEST_SIZE != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (!siv_cmac_aes128_decrypt_message(&instance->siv, nonce_length, nonce,
+                                       assoc_length, assoc,
+                                       plaintext_length, plaintext, ciphertext))
+    return 0;
+
+  return 1;
+}
diff --git a/siv_nettle_int.c b/siv_nettle_int.c
new file mode 100644
index 0000000..714eff6
--- /dev/null
+++ b/siv_nettle_int.c
@@ -0,0 +1,452 @@
+/* This is a single-file implementation of AES-SIV-CMAC-256 based on
+   a patch for GNU Nettle by Nikos Mavrogiannopoulos */
+
+/*
+   AES-CMAC-128 (rfc 4493)
+   Copyright (C) Stefan Metzmacher 2012
+   Copyright (C) Jeremy Allison 2012
+   Copyright (C) Michael Adam 2012
+   Copyright (C) 2017, Red Hat Inc.
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+/* siv-aes128.c, siv-cmac.c, siv.h
+
+   AES-SIV, RFC5297
+   SIV-CMAC, RFC5297
+
+   Copyright (C) 2017 Nikos Mavrogiannopoulos
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+/* cmac.h, siv-cmac.h, cmac-aes128.c
+
+   CMAC mode, as specified in RFC4493
+   SIV-CMAC mode, as specified in RFC5297
+   CMAC using AES128 as the underlying cipher.
+
+   Copyright (C) 2017 Red Hat, Inc.
+
+   Contributed by Nikos Mavrogiannopoulos
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+
+# include "config.h"
+
+#include <assert.h>
+#include <string.h>
+
+#include "nettle/aes.h"
+#include "nettle/ctr.h"
+#include "nettle/macros.h"
+#include "nettle/memxor.h"
+#include "nettle/memops.h"
+
+#include "nettle/nettle-types.h"
+
+/* For SIV, the block size of the block cipher shall be 128 bits. */
+#define SIV_BLOCK_SIZE  16
+#define SIV_DIGEST_SIZE 16
+#define SIV_MIN_NONCE_SIZE 1
+
+/*
+ * SIV mode requires the aad and plaintext when building the IV, which
+ * prevents streaming processing and it incompatible with the AEAD API.
+ */
+
+/* AES_SIV_CMAC_256 */
+struct siv_cmac_aes128_ctx {
+    struct aes128_ctx         cipher;
+    uint8_t s2vk[AES128_KEY_SIZE];
+};
+
+struct cmac128_ctx
+{
+  /* Key */
+  union nettle_block16 K1;
+  union nettle_block16 K2;
+
+  /* MAC state */
+  union nettle_block16 X;
+
+  /* Block buffer */
+  union nettle_block16 block;
+  size_t index;
+};
+
+/* shift one and XOR with 0x87. */
+static void
+_cmac128_block_mulx(union nettle_block16 *dst,
+	   const union nettle_block16 *src)
+{
+  uint64_t b1 = READ_UINT64(src->b);
+  uint64_t b2 = READ_UINT64(src->b+8);
+
+  b1 = (b1 << 1) | (b2 >> 63);
+  b2 <<= 1;
+
+  if (src->b[0] & 0x80)
+    b2 ^= 0x87;
+
+  WRITE_UINT64(dst->b, b1);
+  WRITE_UINT64(dst->b+8, b2);
+}
+
+static void
+cmac128_set_key(struct cmac128_ctx *ctx, const void *cipher,
+		nettle_cipher_func *encrypt)
+{
+  static const uint8_t const_zero[] = {
+    0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00
+  };
+  union nettle_block16 *L = &ctx->block;
+  memset(ctx, 0, sizeof(*ctx));
+
+  /* step 1 - generate subkeys k1 and k2 */
+  encrypt(cipher, 16, L->b, const_zero);
+
+  _cmac128_block_mulx(&ctx->K1, L);
+  _cmac128_block_mulx(&ctx->K2, &ctx->K1);
+}
+
+#define MIN(x,y) ((x)<(y)?(x):(y))
+
+static void
+cmac128_update(struct cmac128_ctx *ctx, const void *cipher,
+	       nettle_cipher_func *encrypt,
+	       size_t msg_len, const uint8_t *msg)
+{
+  union nettle_block16 Y;
+  /*
+   * check if we expand the block
+   */
+  if (ctx->index < 16)
+    {
+      size_t len = MIN(16 - ctx->index, msg_len);
+      memcpy(&ctx->block.b[ctx->index], msg, len);
+      msg += len;
+      msg_len -= len;
+      ctx->index += len;
+    }
+
+  if (msg_len == 0) {
+    /* if it is still the last block, we are done */
+    return;
+  }
+
+  /*
+   * now checksum everything but the last block
+   */
+  memxor3(Y.b, ctx->X.b, ctx->block.b, 16);
+  encrypt(cipher, 16, ctx->X.b, Y.b);
+
+  while (msg_len > 16)
+    {
+      memxor3(Y.b, ctx->X.b, msg, 16);
+      encrypt(cipher, 16, ctx->X.b, Y.b);
+      msg += 16;
+      msg_len -= 16;
+    }
+
+  /*
+   * copy the last block, it will be processed in
+   * cmac128_digest().
+   */
+  memcpy(ctx->block.b, msg, msg_len);
+  ctx->index = msg_len;
+}
+
+static void
+cmac128_digest(struct cmac128_ctx *ctx, const void *cipher,
+	       nettle_cipher_func *encrypt,
+	       unsigned length,
+	       uint8_t *dst)
+{
+  union nettle_block16 Y;
+
+  memset(ctx->block.b+ctx->index, 0, sizeof(ctx->block.b)-ctx->index);
+
+  /* re-use ctx->block for memxor output */
+  if (ctx->index < 16)
+    {
+      ctx->block.b[ctx->index] = 0x80;
+      memxor(ctx->block.b, ctx->K2.b, 16);
+    }
+  else
+    {
+      memxor(ctx->block.b, ctx->K1.b, 16);
+    }
+
+  memxor3(Y.b, ctx->block.b, ctx->X.b, 16);
+
+  assert(length <= 16);
+  if (length == 16)
+    {
+      encrypt(cipher, 16, dst, Y.b);
+    }
+  else
+    {
+      encrypt(cipher, 16, ctx->block.b, Y.b);
+      memcpy(dst, ctx->block.b, length);
+    }
+
+  /* reset state for re-use */
+  memset(&ctx->X, 0, sizeof(ctx->X));
+  ctx->index = 0;
+}
+
+
+#define CMAC128_CTX(type) \
+  { struct cmac128_ctx ctx; type cipher; }
+
+/* NOTE: Avoid using NULL, as we don't include anything defining it. */
+#define CMAC128_SET_KEY(self, set_key, encrypt, cmac_key)	\
+  do {								\
+    (set_key)(&(self)->cipher, (cmac_key));			\
+    if (0) (encrypt)(&(self)->cipher, ~(size_t) 0,		\
+		     (uint8_t *) 0, (const uint8_t *) 0);	\
+    cmac128_set_key(&(self)->ctx, &(self)->cipher,		\
+		(nettle_cipher_func *) (encrypt));		\
+  } while (0)
+
+#define CMAC128_UPDATE(self, encrypt, length, src)		\
+  cmac128_update(&(self)->ctx, &(self)->cipher,			\
+	      (nettle_cipher_func *)encrypt, (length), (src))
+
+#define CMAC128_DIGEST(self, encrypt, length, digest)		\
+  (0 ? (encrypt)(&(self)->cipher, ~(size_t) 0,			\
+		 (uint8_t *) 0, (const uint8_t *) 0)		\
+     : cmac128_digest(&(self)->ctx, &(self)->cipher,		\
+		  (nettle_cipher_func *) (encrypt),		\
+		  (length), (digest)))
+
+struct cmac_aes128_ctx CMAC128_CTX(struct aes128_ctx);
+
+static void
+cmac_aes128_set_key(struct cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+  CMAC128_SET_KEY(ctx, aes128_set_encrypt_key, aes128_encrypt, key);
+}
+
+static void
+cmac_aes128_update (struct cmac_aes128_ctx *ctx,
+		   size_t length, const uint8_t *data)
+{
+  CMAC128_UPDATE (ctx, aes128_encrypt, length, data);
+}
+
+static void
+cmac_aes128_digest(struct cmac_aes128_ctx *ctx,
+		  size_t length, uint8_t *digest)
+{
+  CMAC128_DIGEST(ctx, aes128_encrypt, length, digest);
+}
+
+static const uint8_t const_one[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x01
+};
+
+static const uint8_t const_zero[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00
+};
+
+static
+void _siv_s2v(nettle_set_key_func *cmac_set_key,
+	      nettle_hash_update_func *cmac_update,
+	      nettle_hash_digest_func *cmac_digest,
+	      size_t cmac_ctx_size,
+	      const uint8_t *s2vk, size_t alength, const uint8_t *adata,
+              size_t nlength, const uint8_t *nonce,
+              size_t plength, const uint8_t *pdata,
+              uint8_t *v)
+{
+  uint8_t ctx[sizeof(struct cmac128_ctx)+sizeof(struct aes_ctx)];
+  union nettle_block16 D, S, T;
+
+  assert(cmac_ctx_size <= sizeof (ctx));
+
+  cmac_set_key(ctx, s2vk);
+
+  if (nlength == 0 && alength == 0) {
+    cmac_update(ctx, 16, const_one);
+    cmac_digest(ctx, 16, v);
+    return;
+  }
+
+  cmac_update(ctx, 16, const_zero);
+  cmac_digest(ctx, 16, D.b);
+
+  if (1) {
+    _cmac128_block_mulx(&D, &D);
+    cmac_update(ctx, alength, adata);
+    cmac_digest(ctx, 16, S.b);
+
+    memxor(D.b, S.b, 16);
+  }
+
+  if (nlength > 0) {
+    _cmac128_block_mulx(&D, &D);
+    cmac_update(ctx, nlength, nonce);
+    cmac_digest(ctx, 16, S.b);
+
+    memxor(D.b, S.b, 16);
+  }
+
+  /* Sn */
+  if (plength >= 16) {
+    cmac_update(ctx, plength-16, pdata);
+
+    pdata += plength-16;
+
+    memxor3(T.b, pdata, D.b, 16);
+  } else {
+    union nettle_block16 pad;
+
+    _cmac128_block_mulx(&T, &D);
+    memcpy(pad.b, pdata, plength);
+    pad.b[plength] = 0x80;
+    if (plength+1 < 16)
+      memset(&pad.b[plength+1], 0, 16-plength-1);
+
+    memxor(T.b, pad.b, 16);
+  }
+
+  cmac_update(ctx, 16, T.b);
+  cmac_digest(ctx, 16, v);
+}
+
+static void
+siv_cmac_aes128_set_key(struct siv_cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+  memcpy(ctx->s2vk, key, 16);
+  aes128_set_encrypt_key(&ctx->cipher, key+16);
+}
+
+static void
+siv_cmac_aes128_encrypt_message(struct siv_cmac_aes128_ctx *ctx,
+				size_t nlength, const uint8_t *nonce,
+				size_t alength, const uint8_t *adata,
+				size_t clength, uint8_t *dst, const uint8_t *src)
+{
+  union nettle_block16 siv;
+  size_t slength;
+
+  assert (clength >= SIV_DIGEST_SIZE);
+  slength = clength - SIV_DIGEST_SIZE;
+
+  /* create CTR nonce */
+  _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+	   (nettle_hash_update_func*)cmac_aes128_update,
+	   (nettle_hash_digest_func*)cmac_aes128_digest,
+	   sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+	   nlength, nonce, slength, src, siv.b);
+  memcpy(dst, siv.b, SIV_DIGEST_SIZE);
+  siv.b[8] &= ~0x80;
+  siv.b[12] &= ~0x80;
+
+  ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+            siv.b, slength, dst+SIV_DIGEST_SIZE, src);
+}
+
+static int
+siv_cmac_aes128_decrypt_message(struct siv_cmac_aes128_ctx *ctx,
+				size_t nlength, const uint8_t *nonce,
+				size_t alength, const uint8_t *adata,
+				size_t mlength, uint8_t *dst, const uint8_t *src)
+{
+  union nettle_block16 siv;
+  union nettle_block16 ctr;
+
+  memcpy(ctr.b, src, SIV_DIGEST_SIZE);
+  ctr.b[8] &= ~0x80;
+  ctr.b[12] &= ~0x80;
+
+  ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+            ctr.b, mlength, dst, src+SIV_DIGEST_SIZE);
+
+  /* create CTR nonce */
+  _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+	   (nettle_hash_update_func*)cmac_aes128_update,
+	   (nettle_hash_digest_func*)cmac_aes128_digest,
+	   sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+	   nlength, nonce, mlength, dst, siv.b);
+
+  return memeql_sec(siv.b, src, SIV_DIGEST_SIZE);
+}
+
diff --git a/smooth.c b/smooth.c
new file mode 100644
index 0000000..4c350e9
--- /dev/null
+++ b/smooth.c
@@ -0,0 +1,368 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing time smoothing.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "reference.h"
+#include "smooth.h"
+#include "util.h"
+
+/*
+  Time smoothing determines an offset that needs to be applied to the cooked
+  time to make it smooth for external observers.  Observed offset and frequency
+  change slowly and there are no discontinuities.  This can be used on an NTP
+  server to make it easier for the clients to track the time and keep their
+  clocks close together even when large offset or frequency corrections are
+  applied to the server's clock (e.g. after being offline for longer time).
+
+  Accumulated offset and frequency are smoothed out in three stages.  In the
+  first stage, the frequency is changed at a constant rate (wander) up to a
+  maximum, in the second stage the frequency stays at the maximum for as long
+  as needed and in the third stage the frequency is brought back to zero.
+
+              |
+    max_freq  +-------/--------\-------------
+              |      /|        |\
+        freq  |     / |        | \
+              |    /  |        |  \
+              |   /   |        |   \
+           0  +--/----+--------+----\--------
+              | /     |        |    |    time
+              |/      |        |    |
+
+        stage     1       2      3
+
+  Integral of this function is the smoothed out offset.  It's a continuous
+  piecewise polynomial with two quadratic parts and one linear.
+*/
+
+struct stage {
+  double wander;
+  double length;
+};
+
+#define NUM_STAGES 3
+
+static struct stage stages[NUM_STAGES];
+
+/* Enabled/disabled smoothing */
+static int enabled;
+
+/* Enabled/disabled mode where only leap seconds are smoothed out and normal
+   offset/frequency changes are ignored */
+static int leap_only_mode;
+
+/* Maximum skew/max_wander ratio to start updating offset and frequency */
+#define UNLOCK_SKEW_WANDER_RATIO 10000
+
+static int locked;
+
+/* Maximum wander and frequency offset */
+static double max_wander;
+static double max_freq;
+
+/* Frequency offset, time offset and the time of the last smoothing update */
+static double smooth_freq;
+static double smooth_offset;
+static struct timespec last_update;
+
+
+static void
+get_smoothing(struct timespec *now, double *poffset, double *pfreq,
+              double *pwander)
+{
+  double elapsed, length, offset, freq, wander;
+  int i;
+
+  elapsed = UTI_DiffTimespecsToDouble(now, &last_update);
+
+  offset = smooth_offset;
+  freq = smooth_freq;
+  wander = 0.0;
+
+  for (i = 0; i < NUM_STAGES; i++) {
+    if (elapsed <= 0.0)
+      break;
+
+    length = stages[i].length;
+    if (length >= elapsed)
+      length = elapsed;
+
+    wander = stages[i].wander;
+    offset -= length * (2.0 * freq + wander * length) / 2.0;
+    freq += wander * length;
+    elapsed -= length;
+  }
+
+  if (elapsed > 0.0) {
+    wander = 0.0;
+    offset -= elapsed * freq;
+  }
+
+  *poffset = offset;
+  *pfreq = freq;
+  if (pwander)
+    *pwander = wander;
+}
+
+static void
+update_stages(void)
+{
+  double s1, s2, s, l1, l2, l3, lc, f, f2, l1t[2], l3t[2], err[2];
+  int i, dir;
+
+  /* Prepare the three stages so that the integral of the frequency offset
+     is equal to the offset that should be smoothed out */
+
+  s1 = smooth_offset / max_wander;
+  s2 = SQUARE(smooth_freq) / (2.0 * SQUARE(max_wander));
+  
+  /* Calculate the lengths of the 1st and 3rd stage assuming there is no
+     frequency limit.  The direction of the 1st stage is selected so that
+     the lengths will not be negative.  With extremely small offsets both
+     directions may give a negative length due to numerical errors, so select
+     the one which gives a smaller error. */
+
+  for (i = 0, dir = -1; i <= 1; i++, dir += 2) {
+    err[i] = 0.0;
+    s = dir * s1 + s2;
+
+    if (s < 0.0) {
+      err[i] += -s;
+      s = 0.0;
+    }
+
+    l3t[i] = sqrt(s);
+    l1t[i] = l3t[i] - dir * smooth_freq / max_wander;
+
+    if (l1t[i] < 0.0) {
+      err[i] += l1t[i] * l1t[i];
+      l1t[i] = 0.0;
+    }
+  }
+
+  if (err[0] < err[1]) {
+    l1 = l1t[0];
+    l3 = l3t[0];
+    dir = -1;
+  } else {
+    l1 = l1t[1];
+    l3 = l3t[1];
+    dir = 1;
+  }
+
+  l2 = 0.0;
+
+  /* If the limit was reached, shorten 1st+3rd stages and set a 2nd stage */
+  f = dir * smooth_freq + l1 * max_wander - max_freq;
+  if (f > 0.0) {
+    lc = f / max_wander;
+
+    /* No 1st stage if the frequency is already above the maximum */
+    if (lc > l1) {
+      lc = l1;
+      f2 = dir * smooth_freq;
+    } else {
+      f2 = max_freq;
+    }
+
+    l2 = lc * (2.0 + f / f2);
+    l1 -= lc;
+    l3 -= lc;
+  }
+
+  stages[0].wander = dir * max_wander;
+  stages[0].length = l1;
+  stages[1].wander = 0.0;
+  stages[1].length = l2;
+  stages[2].wander = -dir * max_wander;
+  stages[2].length = l3;
+
+  for (i = 0; i < NUM_STAGES; i++) {
+    DEBUG_LOG("Smooth stage %d wander %e length %f",
+              i + 1, stages[i].wander, stages[i].length);
+  }
+}
+
+static void
+update_smoothing(struct timespec *now, double offset, double freq)
+{
+  /* Don't accept offset/frequency until the clock has stabilized */
+  if (locked) {
+    if (REF_GetSkew() / max_wander < UNLOCK_SKEW_WANDER_RATIO || leap_only_mode)
+      SMT_Activate(now);
+    return;
+  }
+
+  get_smoothing(now, &smooth_offset, &smooth_freq, NULL);
+  smooth_offset += offset;
+  smooth_freq = (smooth_freq - freq) / (1.0 - freq);
+  last_update = *now;
+
+  update_stages();
+
+  DEBUG_LOG("Smooth offset %e freq %e", smooth_offset, smooth_freq);
+}
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  double delta;
+
+  if (change_type == LCL_ChangeAdjust) {
+    if (leap_only_mode)
+      update_smoothing(cooked, 0.0, 0.0);
+    else
+      update_smoothing(cooked, doffset, dfreq);
+  }
+
+  if (!UTI_IsZeroTimespec(&last_update))
+    UTI_AdjustTimespec(&last_update, cooked, &last_update, &delta, dfreq, doffset);
+}
+
+void SMT_Initialise(void)
+{
+  CNF_GetSmooth(&max_freq, &max_wander, &leap_only_mode);
+  if (max_freq <= 0.0 || max_wander <= 0.0) {
+      enabled = 0;
+      return;
+  }
+
+  enabled = 1;
+  locked = 1;
+
+  /* Convert from ppm */
+  max_freq *= 1e-6;
+  max_wander *= 1e-6;
+
+  UTI_ZeroTimespec(&last_update);
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+}
+
+void SMT_Finalise(void)
+{
+  if (!enabled)
+    return;
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+}
+
+int SMT_IsEnabled(void)
+{
+  return enabled;
+}
+
+double
+SMT_GetOffset(struct timespec *now)
+{
+  double offset, freq;
+
+  if (!enabled)
+    return 0.0;
+  
+  get_smoothing(now, &offset, &freq, NULL);
+
+  return offset;
+}
+
+void
+SMT_Activate(struct timespec *now)
+{
+  if (!enabled || !locked)
+    return;
+
+  LOG(LOGS_INFO, "Time smoothing activated%s", leap_only_mode ?
+      " (leap seconds only)" : "");
+  locked = 0;
+  last_update = *now;
+}
+
+void
+SMT_Reset(struct timespec *now)
+{
+  int i;
+
+  if (!enabled)
+    return;
+
+  smooth_offset = 0.0;
+  smooth_freq = 0.0;
+  last_update = *now;
+
+  for (i = 0; i < NUM_STAGES; i++)
+    stages[i].wander = stages[i].length = 0.0;
+}
+
+void
+SMT_Leap(struct timespec *now, int leap)
+{
+  /* When the leap-only mode is disabled, the leap second will be accumulated
+     in handle_slew() as a normal offset */
+  if (!enabled || !leap_only_mode)
+    return;
+
+  update_smoothing(now, leap, 0.0);
+}
+
+int
+SMT_GetSmoothingReport(RPT_SmoothingReport *report, struct timespec *now)
+{
+  double length, elapsed;
+  int i;
+
+  if (!enabled)
+    return 0;
+
+  report->active = !locked;
+  report->leap_only = leap_only_mode;
+
+  get_smoothing(now, &report->offset, &report->freq_ppm, &report->wander_ppm);
+
+  /* Convert to ppm and negate (positive values mean faster/speeding up) */
+  report->freq_ppm *= -1.0e6;
+  report->wander_ppm *= -1.0e6;
+
+  elapsed = UTI_DiffTimespecsToDouble(now, &last_update);
+  if (!locked && elapsed >= 0.0) {
+    for (i = 0, length = 0.0; i < NUM_STAGES; i++)
+      length += stages[i].length;
+    report->last_update_ago = elapsed;
+    report->remaining_time = elapsed < length ? length - elapsed : 0.0;
+  } else {
+    report->last_update_ago = 0.0;
+    report->remaining_time = 0.0;
+  }
+
+  return 1;
+}
diff --git a/smooth.h b/smooth.h
new file mode 100644
index 0000000..4e84504
--- /dev/null
+++ b/smooth.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module implements time smoothing.
+  */
+
+#ifndef GOT_SMOOTH_H
+#define GOT_SMOOTH_H
+
+#include "reports.h"
+
+extern void SMT_Initialise(void);
+
+extern void SMT_Finalise(void);
+
+extern int SMT_IsEnabled(void);
+
+extern double SMT_GetOffset(struct timespec *now);
+
+extern void SMT_Activate(struct timespec *now);
+
+extern void SMT_Reset(struct timespec *now);
+
+extern void SMT_Leap(struct timespec *now, int leap);
+
+extern int SMT_GetSmoothingReport(RPT_SmoothingReport *report, struct timespec *now);
+
+#endif
diff --git a/socket.c b/socket.c
new file mode 100644
index 0000000..8a5d046
--- /dev/null
+++ b/socket.c
@@ -0,0 +1,1636 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Timo Teras  2009
+ * Copyright (C) Miroslav Lichvar  2009, 2013-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file implements socket operations.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include <linux/errqueue.h>
+#include <linux/net_tstamp.h>
+#endif
+
+#include "socket.h"
+#include "array.h"
+#include "logging.h"
+#include "privops.h"
+#include "ptp.h"
+#include "util.h"
+
+#define INVALID_SOCK_FD (-4)
+#define CMSG_BUF_SIZE 256
+
+union sockaddr_all {
+  struct sockaddr_in in4;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 in6;
+#endif
+  struct sockaddr_un un;
+  struct sockaddr sa;
+};
+
+struct Message {
+  union sockaddr_all name;
+  struct iovec iov;
+  /* Buffer of sufficient length for all expected messages */
+  struct {
+    /* Extra space for Ethernet, IPv4/IPv6, and UDP headers in
+       timestamped messages received from the Linux error queue */
+    uint8_t l234_headers[64];
+    union {
+      NTP_Packet ntp_msg;
+      PTP_NtpMessage ptp_msg;
+      CMD_Request cmd_request;
+      CMD_Reply cmd_reply;
+    } msg;
+  } msg_buf;
+  /* Aligned buffer for control messages */
+  struct cmsghdr cmsg_buf[CMSG_BUF_SIZE / sizeof (struct cmsghdr)];
+};
+
+#ifdef HAVE_RECVMMSG
+#define MAX_RECV_MESSAGES 16
+#define MessageHeader mmsghdr
+#else
+/* Compatible with mmsghdr */
+struct MessageHeader {
+  struct msghdr msg_hdr;
+  unsigned int msg_len;
+};
+
+#define MAX_RECV_MESSAGES 1
+#endif
+
+static int initialised;
+
+/* Flags indicating in which IP families sockets can be requested */
+static int ip4_enabled;
+static int ip6_enabled;
+
+/* Flags supported by socket() */
+static int supported_socket_flags;
+
+/* Arrays of Message, MessageHeader, and SCK_Message */
+static ARR_Instance recv_messages;
+static ARR_Instance recv_headers;
+static ARR_Instance recv_sck_messages;
+
+static unsigned int received_messages;
+
+static int (*priv_bind_function)(int sock_fd, struct sockaddr *address,
+                                 socklen_t address_len);
+
+/* ================================================== */
+
+static void
+prepare_buffers(unsigned int n)
+{
+  struct MessageHeader *hdr;
+  struct Message *msg;
+  unsigned int i;
+
+  for (i = 0; i < n; i++) {
+    msg = ARR_GetElement(recv_messages, i);
+    hdr = ARR_GetElement(recv_headers, i);
+
+    msg->iov.iov_base = &msg->msg_buf;
+    msg->iov.iov_len = sizeof (msg->msg_buf);
+    hdr->msg_hdr.msg_name = &msg->name;
+    hdr->msg_hdr.msg_namelen = sizeof (msg->name);
+    hdr->msg_hdr.msg_iov = &msg->iov;
+    hdr->msg_hdr.msg_iovlen = 1;
+    hdr->msg_hdr.msg_control = msg->cmsg_buf;
+    hdr->msg_hdr.msg_controllen = sizeof (msg->cmsg_buf);
+    hdr->msg_hdr.msg_flags = 0;
+    hdr->msg_len = 0;
+  }
+}
+
+/* ================================================== */
+
+static const char *
+domain_to_string(int domain)
+{
+  switch (domain) {
+    case AF_INET:
+      return "IPv4";
+#ifdef AF_INET6
+    case AF_INET6:
+      return "IPv6";
+#endif
+    case AF_UNIX:
+      return "Unix";
+    case AF_UNSPEC:
+      return "UNSPEC";
+    default:
+      return "?";
+  }
+}
+
+/* ================================================== */
+
+#if defined(SOCK_CLOEXEC) || defined(SOCK_NONBLOCK)
+static int
+check_socket_flag(int sock_flag, int fd_flag, int fs_flag)
+{
+  int sock_fd, fd_flags, fs_flags;
+
+  sock_fd = socket(AF_INET, SOCK_DGRAM | sock_flag, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  fd_flags = fcntl(sock_fd, F_GETFD);
+  fs_flags = fcntl(sock_fd, F_GETFL);
+
+  close(sock_fd);
+
+  if (fd_flags == -1 || (fd_flags & fd_flag) != fd_flag ||
+      fs_flags == -1 || (fs_flags & fs_flag) != fs_flag)
+    return 0;
+
+  return 1;
+}
+#endif
+
+/* ================================================== */
+
+static int
+set_socket_nonblock(int sock_fd)
+{
+  if (fcntl(sock_fd, F_SETFL, O_NONBLOCK) < 0) {
+    DEBUG_LOG("Could not set O_NONBLOCK : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+get_open_flags(int flags)
+{
+  int r = supported_socket_flags;
+
+#ifdef SOCK_NONBLOCK
+  if (flags & SCK_FLAG_BLOCK)
+    r &= ~SOCK_NONBLOCK;
+#endif
+
+  return r;
+}
+
+/* ================================================== */
+
+static int
+set_socket_flags(int sock_fd, int flags)
+{
+  /* Close the socket automatically on exec */
+  if (
+#ifdef SOCK_CLOEXEC
+      (supported_socket_flags & SOCK_CLOEXEC) == 0 &&
+#endif
+      !UTI_FdSetCloexec(sock_fd))
+    return 0;
+
+  /* Enable non-blocking mode */
+  if ((flags & SCK_FLAG_BLOCK) == 0 &&
+#ifdef SOCK_NONBLOCK
+      (supported_socket_flags & SOCK_NONBLOCK) == 0 &&
+#endif
+      !set_socket_nonblock(sock_fd))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_socket(int domain, int type, int flags)
+{
+  int sock_fd;
+
+  sock_fd = socket(domain, type | get_open_flags(flags), 0);
+
+  if (sock_fd < 0) {
+    DEBUG_LOG("Could not open %s socket : %s",
+              domain_to_string(domain), strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!set_socket_flags(sock_fd, flags)) {
+    close(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+open_socket_pair(int domain, int type, int flags, int *other_fd)
+{
+  int sock_fds[2];
+
+  if (socketpair(domain, type | get_open_flags(flags), 0, sock_fds) < 0) {
+    DEBUG_LOG("Could not open %s socket : %s",
+              domain_to_string(domain), strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!set_socket_flags(sock_fds[0], flags) || !set_socket_flags(sock_fds[1], flags)) {
+    close(sock_fds[0]);
+    close(sock_fds[1]);
+    return INVALID_SOCK_FD;
+  }
+
+  *other_fd = sock_fds[1];
+
+  return sock_fds[0];
+}
+
+/* ================================================== */
+
+static int
+set_socket_options(int sock_fd, int flags)
+{
+  /* Make the socket capable of sending broadcast packets if requested */
+  if (flags & SCK_FLAG_BROADCAST && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_BROADCAST, 1))
+    ;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+set_ip_options(int sock_fd, int family, int flags)
+{
+#if defined(FEAT_IPV6) && defined(IPV6_V6ONLY)
+  /* Receive only IPv6 packets on an IPv6 socket */
+  if (family == IPADDR_INET6 && !SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_V6ONLY, 1))
+    return 0;
+#endif
+
+  /* Provide destination address of received packets if requested */
+  if (flags & SCK_FLAG_RX_DEST_ADDR) {
+    if (family == IPADDR_INET4) {
+#ifdef HAVE_IN_PKTINFO
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_PKTINFO, 1))
+        ;
+#elif defined(IP_RECVDSTADDR)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_RECVDSTADDR, 1))
+        ;
+#endif
+    }
+#ifdef FEAT_IPV6
+    else if (family == IPADDR_INET6) {
+#ifdef HAVE_IN6_PKTINFO
+#ifdef IPV6_RECVPKTINFO
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, 1))
+        ;
+#else
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_PKTINFO, 1))
+        ;
+#endif
+#endif
+    }
+#endif
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+is_any_address(IPAddr *addr)
+{
+  IPAddr any_addr;
+
+  SCK_GetAnyLocalIPAddress(addr->family, &any_addr);
+
+  return UTI_CompareIPs(&any_addr, addr, NULL) == 0;
+}
+
+/* ================================================== */
+
+static int
+bind_device(int sock_fd, const char *iface)
+{
+#ifdef SO_BINDTODEVICE
+  if (setsockopt(sock_fd, SOL_SOCKET, SO_BINDTODEVICE, iface, strlen(iface) + 1) < 0) {
+    DEBUG_LOG("Could not bind socket to %s : %s", iface, strerror(errno));
+    return 0;
+  }
+  return 1;
+#else
+  DEBUG_LOG("Could not bind socket to %s : %s", iface, "Not supported");
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+bind_ip_address(int sock_fd, IPSockAddr *addr, int flags)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+  int s;
+
+  /* Make the socket capable of re-using an old address if binding to a specific port */
+  if (addr->port > 0 && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_REUSEADDR, 1))
+    ;
+
+#if defined(LINUX) && defined(SO_REUSEPORT)
+  /* Allow multiple instances to bind to the same port in order to enable load
+     balancing.  Don't enable this option on non-Linux systems as it has
+     a slightly different meaning there (with some important implications). */
+  if (addr->port > 0 && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_REUSEPORT, 1))
+    ;
+#endif
+
+#ifdef IP_FREEBIND
+  /* Allow binding to an address that doesn't exist yet */
+  if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_FREEBIND, 1))
+    ;
+#endif
+
+  saddr_len = SCK_IPSockAddrToSockaddr(addr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (saddr_len == 0)
+    return 0;
+
+  if (flags & SCK_FLAG_PRIV_BIND && priv_bind_function)
+    s = priv_bind_function(sock_fd, &saddr.sa, saddr_len);
+  else
+    s = bind(sock_fd, &saddr.sa, saddr_len);
+
+  if (s < 0) {
+    DEBUG_LOG("Could not bind socket to %s : %s",
+              UTI_IPSockAddrToString(addr), strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+connect_ip_address(int sock_fd, IPSockAddr *addr)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+
+  saddr_len = SCK_IPSockAddrToSockaddr(addr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (saddr_len == 0)
+    return 0;
+
+  if (connect(sock_fd, &saddr.sa, saddr_len) < 0 && errno != EINPROGRESS) {
+    DEBUG_LOG("Could not connect socket to %s : %s",
+              UTI_IPSockAddrToString(addr), strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_ip_socket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface,
+               int type, int flags)
+{
+  int domain, family, sock_fd;
+
+  if (local_addr)
+    family = local_addr->ip_addr.family;
+  else if (remote_addr)
+    family = remote_addr->ip_addr.family;
+  else
+    family = IPADDR_INET4;
+
+  switch (family) {
+    case IPADDR_INET4:
+      if (!ip4_enabled)
+        return INVALID_SOCK_FD;
+      domain = AF_INET;
+      break;
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      if (!ip6_enabled)
+        return INVALID_SOCK_FD;
+      domain = AF_INET6;
+      break;
+#endif
+    default:
+      DEBUG_LOG("Unspecified family");
+      return INVALID_SOCK_FD;
+  }
+
+  sock_fd = open_socket(domain, type, flags);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!set_socket_options(sock_fd, flags))
+    goto error;
+
+  if (!set_ip_options(sock_fd, family, flags))
+    goto error;
+
+  if (iface && !bind_device(sock_fd, iface))
+    goto error;
+
+  /* Bind the socket if a non-any local address/port was specified */
+  if (local_addr && local_addr->ip_addr.family != IPADDR_UNSPEC &&
+      (local_addr->port != 0 || !is_any_address(&local_addr->ip_addr)) &&
+      !bind_ip_address(sock_fd, local_addr, flags))
+    goto error;
+
+  /* Connect the socket if a remote address was specified */
+  if (remote_addr && remote_addr->ip_addr.family != IPADDR_UNSPEC &&
+      !connect_ip_address(sock_fd, remote_addr))
+    goto error;
+
+  if (remote_addr || local_addr)
+    DEBUG_LOG("Opened %s%s socket fd=%d%s%s%s%s",
+              type == SOCK_DGRAM ? "UDP" : type == SOCK_STREAM ? "TCP" : "?",
+              family == IPADDR_INET4 ? "v4" : "v6",
+              sock_fd,
+              remote_addr ? " remote=" : "",
+              remote_addr ? UTI_IPSockAddrToString(remote_addr) : "",
+              local_addr ? " local=" : "",
+              local_addr ? UTI_IPSockAddrToString(local_addr) : "");
+
+  return sock_fd;
+
+error:
+  SCK_CloseSocket(sock_fd);
+  return INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+bind_unix_address(int sock_fd, const char *addr, int flags)
+{
+  union sockaddr_all saddr;
+
+  memset(&saddr, 0, sizeof (saddr));
+
+  if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s", addr) >=
+      sizeof (saddr.un.sun_path)) {
+    DEBUG_LOG("Unix socket path %s too long", addr);
+    return 0;
+  }
+  saddr.un.sun_family = AF_UNIX;
+
+  if (unlink(addr) < 0)
+    DEBUG_LOG("Could not remove %s : %s", addr, strerror(errno));
+
+  /* PRV_BindSocket() doesn't support Unix sockets yet */
+  if (bind(sock_fd, &saddr.sa, sizeof (saddr.un)) < 0) {
+    DEBUG_LOG("Could not bind Unix socket to %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  /* Allow access to everyone with access to the directory if requested */
+  if (flags & SCK_FLAG_ALL_PERMISSIONS && chmod(addr, 0666) < 0) {
+    DEBUG_LOG("Could not change permissions of %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+connect_unix_address(int sock_fd, const char *addr)
+{
+  union sockaddr_all saddr;
+
+  memset(&saddr, 0, sizeof (saddr));
+
+  if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s", addr) >=
+      sizeof (saddr.un.sun_path)) {
+    DEBUG_LOG("Unix socket path %s too long", addr);
+    return 0;
+  }
+  saddr.un.sun_family = AF_UNIX;
+
+  if (connect(sock_fd, &saddr.sa, sizeof (saddr.un)) < 0) {
+    DEBUG_LOG("Could not connect Unix socket to %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_unix_socket(const char *remote_addr, const char *local_addr, int type, int flags)
+{
+  int sock_fd;
+
+  sock_fd = open_socket(AF_UNIX, type, flags);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!set_socket_options(sock_fd, flags))
+    goto error;
+
+  /* Bind the socket if a local address was specified */
+  if (local_addr && !bind_unix_address(sock_fd, local_addr, flags))
+    goto error;
+
+  /* Connect the socket if a remote address was specified */
+  if (remote_addr && !connect_unix_address(sock_fd, remote_addr))
+    goto error;
+
+  DEBUG_LOG("Opened Unix socket fd=%d%s%s%s%s",
+            sock_fd,
+            remote_addr ? " remote=" : "", remote_addr ? remote_addr : "",
+            local_addr ? " local=" : "", local_addr ? local_addr : "");
+
+  return sock_fd;
+
+error:
+  SCK_RemoveSocket(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  return INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+open_unix_socket_pair(int type, int flags, int *other_fd)
+{
+  int sock_fd;
+
+  sock_fd = open_socket_pair(AF_UNIX, type, flags, other_fd);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  DEBUG_LOG("Opened Unix socket pair fd1=%d fd2=%d", sock_fd, *other_fd);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+get_recv_flags(int flags)
+{
+  int recv_flags = 0;
+
+  if (flags & SCK_FLAG_MSG_ERRQUEUE) {
+#ifdef MSG_ERRQUEUE
+    recv_flags |= MSG_ERRQUEUE;
+#else
+    assert(0);
+#endif
+  }
+
+  return recv_flags;
+}
+
+/* ================================================== */
+
+static void
+handle_recv_error(int sock_fd, int flags)
+{
+#ifdef MSG_ERRQUEUE
+  /* If reading from the error queue failed, the select() exception should
+     be for a socket error.  Clear the error to avoid a busy loop. */
+  if (flags & SCK_FLAG_MSG_ERRQUEUE) {
+    int error = 0;
+
+    if (SCK_GetIntOption(sock_fd, SOL_SOCKET, SO_ERROR, &error))
+      errno = error;
+  }
+#endif
+
+  DEBUG_LOG("Could not receive message fd=%d : %s", sock_fd, strerror(errno));
+}
+
+/* ================================================== */
+
+static void
+log_message(int sock_fd, int direction, SCK_Message *message, const char *prefix,
+            const char *error)
+{
+  const char *local_addr, *remote_addr;
+  char if_index[20], tss[10], tsif[20], tslen[20];
+
+  if (DEBUG <= 0 || log_min_severity > LOGS_DEBUG)
+    return;
+
+  remote_addr = NULL;
+  local_addr = NULL;
+  if_index[0] = '\0';
+  tss[0] = '\0';
+  tsif[0] = '\0';
+  tslen[0] = '\0';
+
+  switch (message->addr_type) {
+    case SCK_ADDR_IP:
+      if (message->remote_addr.ip.ip_addr.family != IPADDR_UNSPEC)
+        remote_addr = UTI_IPSockAddrToString(&message->remote_addr.ip);
+      if (message->local_addr.ip.family != IPADDR_UNSPEC)
+        local_addr = UTI_IPToString(&message->local_addr.ip);
+      break;
+    case SCK_ADDR_UNIX:
+      remote_addr = message->remote_addr.path;
+      break;
+    default:
+      break;
+  }
+
+  if (message->if_index != INVALID_IF_INDEX)
+    snprintf(if_index, sizeof (if_index), " if=%d", message->if_index);
+
+  if (direction > 0) {
+    if (!UTI_IsZeroTimespec(&message->timestamp.kernel) ||
+        !UTI_IsZeroTimespec(&message->timestamp.hw))
+      snprintf(tss, sizeof (tss), " tss=%s%s",
+               !UTI_IsZeroTimespec(&message->timestamp.kernel) ? "K" : "",
+               !UTI_IsZeroTimespec(&message->timestamp.hw) ? "H" : "");
+
+    if (message->timestamp.if_index != INVALID_IF_INDEX)
+      snprintf(tsif, sizeof (tsif), " tsif=%d", message->timestamp.if_index);
+
+    if (message->timestamp.l2_length != 0)
+      snprintf(tslen, sizeof (tslen), " tslen=%d", message->timestamp.l2_length);
+  }
+
+  DEBUG_LOG("%s message%s%s%s%s fd=%d len=%d%s%s%s%s%s%s",
+            prefix,
+            remote_addr ? (direction > 0 ? " from " : " to ") : "",
+            remote_addr ? remote_addr : "",
+            local_addr ? (direction > 0 ? " to " : " from ") : "",
+            local_addr ? local_addr : "",
+            sock_fd, message->length, if_index,
+            tss, tsif, tslen,
+            error ? " : " : "", error ? error : "");
+}
+
+/* ================================================== */
+
+static void
+init_message_addresses(SCK_Message *message, SCK_AddressType addr_type)
+{
+  message->addr_type = addr_type;
+
+  switch (addr_type) {
+    case SCK_ADDR_UNSPEC:
+      break;
+    case SCK_ADDR_IP:
+      message->remote_addr.ip.ip_addr.family = IPADDR_UNSPEC;
+      message->remote_addr.ip.port = 0;
+      message->local_addr.ip.family = IPADDR_UNSPEC;
+      break;
+    case SCK_ADDR_UNIX:
+      message->remote_addr.path = NULL;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+init_message_nonaddress(SCK_Message *message)
+{
+  message->data = NULL;
+  message->length = 0;
+  message->if_index = INVALID_IF_INDEX;
+
+  UTI_ZeroTimespec(&message->timestamp.kernel);
+  UTI_ZeroTimespec(&message->timestamp.hw);
+  message->timestamp.if_index = INVALID_IF_INDEX;
+  message->timestamp.l2_length = 0;
+  message->timestamp.tx_flags = 0;
+
+  message->descriptor = INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+match_cmsg(struct cmsghdr *cmsg, int level, int type, size_t length)
+{
+  if (cmsg->cmsg_type == type && cmsg->cmsg_level == level &&
+      (length == 0 || cmsg->cmsg_len == CMSG_LEN(length)))
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+process_header(struct msghdr *msg, int msg_length, int sock_fd, int flags,
+               SCK_Message *message)
+{
+  struct cmsghdr *cmsg;
+  int r = 1;
+
+  if (msg->msg_namelen <= sizeof (union sockaddr_all) &&
+      msg->msg_namelen > sizeof (((struct sockaddr *)msg->msg_name)->sa_family)) {
+    switch (((struct sockaddr *)msg->msg_name)->sa_family) {
+      case AF_INET:
+#ifdef FEAT_IPV6
+      case AF_INET6:
+#endif
+        init_message_addresses(message, SCK_ADDR_IP);
+        SCK_SockaddrToIPSockAddr(msg->msg_name, msg->msg_namelen, &message->remote_addr.ip);
+        break;
+      case AF_UNIX:
+        init_message_addresses(message, SCK_ADDR_UNIX);
+        message->remote_addr.path = ((struct sockaddr_un *)msg->msg_name)->sun_path;
+        break;
+      default:
+        init_message_addresses(message, SCK_ADDR_UNSPEC);
+        DEBUG_LOG("Unexpected address");
+        r = 0;
+        break;
+    }
+  } else {
+    init_message_addresses(message, SCK_ADDR_UNSPEC);
+
+    if (msg->msg_namelen > sizeof (union sockaddr_all)) {
+      DEBUG_LOG("Truncated source address");
+      r = 0;
+    }
+  }
+
+  init_message_nonaddress(message);
+
+  if (msg->msg_iovlen == 1) {
+    message->data = msg->msg_iov[0].iov_base;
+    message->length = msg_length;
+  } else {
+    DEBUG_LOG("Unexpected iovlen");
+    r = 0;
+  }
+
+  if (msg->msg_flags & MSG_TRUNC) {
+    log_message(sock_fd, 1, message, "Truncated", NULL);
+    r = 0;
+  }
+
+  if (msg->msg_flags & MSG_CTRUNC) {
+    log_message(sock_fd, 1, message, "Truncated cmsg in", NULL);
+    r = 0;
+  }
+
+  for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+    if (0) {
+    }
+#ifdef HAVE_IN_PKTINFO
+    else if (match_cmsg(cmsg, IPPROTO_IP, IP_PKTINFO, sizeof (struct in_pktinfo))) {
+      struct in_pktinfo ipi;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&ipi, CMSG_DATA(cmsg), sizeof (ipi));
+      message->local_addr.ip.addr.in4 = ntohl(ipi.ipi_addr.s_addr);
+      message->local_addr.ip.family = IPADDR_INET4;
+      message->if_index = ipi.ipi_ifindex;
+    }
+#elif defined(IP_RECVDSTADDR)
+    else if (match_cmsg(cmsg, IPPROTO_IP, IP_RECVDSTADDR, sizeof (struct in_addr))) {
+      struct in_addr addr;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&addr, CMSG_DATA(cmsg), sizeof (addr));
+      message->local_addr.ip.addr.in4 = ntohl(addr.s_addr);
+      message->local_addr.ip.family = IPADDR_INET4;
+    }
+#endif
+#ifdef HAVE_IN6_PKTINFO
+    else if (match_cmsg(cmsg, IPPROTO_IPV6, IPV6_PKTINFO, sizeof (struct in6_pktinfo))) {
+      struct in6_pktinfo ipi;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&ipi, CMSG_DATA(cmsg), sizeof (ipi));
+      memcpy(&message->local_addr.ip.addr.in6, &ipi.ipi6_addr.s6_addr,
+             sizeof (message->local_addr.ip.addr.in6));
+      message->local_addr.ip.family = IPADDR_INET6;
+      message->if_index = ipi.ipi6_ifindex;
+    }
+#endif
+#ifdef SCM_TIMESTAMP
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMP, sizeof (struct timeval))) {
+      struct timeval tv;
+
+      memcpy(&tv, CMSG_DATA(cmsg), sizeof (tv));
+      UTI_TimevalToTimespec(&tv, &message->timestamp.kernel);
+    }
+#endif
+#ifdef SCM_TIMESTAMPNS
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPNS, sizeof (message->timestamp.kernel))) {
+      memcpy(&message->timestamp.kernel, CMSG_DATA(cmsg), sizeof (message->timestamp.kernel));
+    }
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPING_PKTINFO,
+                        sizeof (struct scm_ts_pktinfo))) {
+      struct scm_ts_pktinfo ts_pktinfo;
+
+      memcpy(&ts_pktinfo, CMSG_DATA(cmsg), sizeof (ts_pktinfo));
+      message->timestamp.if_index = ts_pktinfo.if_index;
+      message->timestamp.l2_length = ts_pktinfo.pkt_length;
+    }
+#endif
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPING,
+                        sizeof (struct scm_timestamping))) {
+      struct scm_timestamping ts3;
+
+      memcpy(&ts3, CMSG_DATA(cmsg), sizeof (ts3));
+      message->timestamp.kernel = ts3.ts[0];
+      message->timestamp.hw = ts3.ts[2];
+    }
+    else if ((match_cmsg(cmsg, SOL_IP, IP_RECVERR, 0) ||
+              match_cmsg(cmsg, SOL_IPV6, IPV6_RECVERR, 0)) &&
+             cmsg->cmsg_len >= CMSG_LEN(sizeof (struct sock_extended_err))) {
+      struct sock_extended_err err;
+
+      memcpy(&err, CMSG_DATA(cmsg), sizeof (err));
+
+      if (err.ee_errno != ENOMSG || err.ee_info != SCM_TSTAMP_SND ||
+          err.ee_origin != SO_EE_ORIGIN_TIMESTAMPING) {
+        log_message(sock_fd, 1, message, "Unexpected extended error in", NULL);
+        r = 0;
+      }
+    }
+#endif
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_RIGHTS, 0)) {
+      if (!(flags & SCK_FLAG_MSG_DESCRIPTOR) || cmsg->cmsg_len != CMSG_LEN(sizeof (int))) {
+        int i, fd;
+
+        DEBUG_LOG("Unexpected SCM_RIGHTS");
+        for (i = 0; CMSG_LEN((i + 1) * sizeof (int)) <= cmsg->cmsg_len; i++) {
+          memcpy(&fd, (char *)CMSG_DATA(cmsg) + i * sizeof (int), sizeof (fd));
+          close(fd);
+        }
+        r = 0;
+      } else {
+        memcpy(&message->descriptor, CMSG_DATA(cmsg), sizeof (message->descriptor));
+      }
+    }
+    else {
+      DEBUG_LOG("Unexpected control message level=%d type=%d len=%d",
+                cmsg->cmsg_level, cmsg->cmsg_type, (int)cmsg->cmsg_len);
+    }
+  }
+
+  if (!r && message->descriptor != INVALID_SOCK_FD)
+    close(message->descriptor);
+
+  return r;
+}
+
+/* ================================================== */
+
+static SCK_Message *
+receive_messages(int sock_fd, int flags, int max_messages, int *num_messages)
+{
+  struct MessageHeader *hdr;
+  SCK_Message *messages;
+  unsigned int i, n, n_ok;
+  int ret, recv_flags = 0;
+
+  assert(initialised);
+
+  *num_messages = 0;
+
+  if (max_messages < 1)
+    return NULL;
+
+  /* Prepare used buffers for new messages */
+  prepare_buffers(received_messages);
+  received_messages = 0;
+
+  messages = ARR_GetElements(recv_sck_messages);
+
+  hdr = ARR_GetElements(recv_headers);
+  n = ARR_GetSize(recv_headers);
+  n = MIN(n, max_messages);
+
+  if (n < 1 || n > MAX_RECV_MESSAGES ||
+      n > ARR_GetSize(recv_messages) || n > ARR_GetSize(recv_sck_messages))
+    assert(0);
+
+  recv_flags = get_recv_flags(flags);
+
+#ifdef HAVE_RECVMMSG
+  ret = recvmmsg(sock_fd, hdr, n, recv_flags, NULL);
+  if (ret >= 0)
+    n = ret;
+#else
+  n = 1;
+  ret = recvmsg(sock_fd, &hdr[0].msg_hdr, recv_flags);
+  if (ret >= 0)
+    hdr[0].msg_len = ret;
+#endif
+
+  if (ret < 0) {
+    handle_recv_error(sock_fd, flags);
+    return NULL;
+  }
+
+  received_messages = n;
+
+  for (i = n_ok = 0; i < n; i++) {
+    hdr = ARR_GetElement(recv_headers, i);
+    if (!process_header(&hdr->msg_hdr, hdr->msg_len, sock_fd, flags, &messages[n_ok]))
+      continue;
+
+    log_message(sock_fd, 1, &messages[n_ok],
+                flags & SCK_FLAG_MSG_ERRQUEUE ? "Received error" : "Received", NULL);
+
+    n_ok++;
+  }
+
+  *num_messages = n_ok;
+
+  return n_ok > 0 ? messages : NULL;
+}
+
+/* ================================================== */
+
+static void *
+add_control_message(struct msghdr *msg, int level, int type, size_t length, size_t buf_length)
+{
+  struct cmsghdr *cmsg;
+  size_t cmsg_space;
+
+  /* Avoid using CMSG_NXTHDR as the one in glibc does not support adding
+     control messages: https://sourceware.org/bugzilla/show_bug.cgi?id=13500 */
+
+  cmsg = msg->msg_control;
+  cmsg_space = CMSG_SPACE(length);
+
+  if (!cmsg || length > buf_length || msg->msg_controllen + cmsg_space > buf_length) {
+    DEBUG_LOG("Could not add control message level=%d type=%d", level, type);
+    return NULL;
+  }
+
+  cmsg = (struct cmsghdr *)((char *)cmsg + msg->msg_controllen);
+
+  memset(cmsg, 0, cmsg_space);
+
+  cmsg->cmsg_level = level;
+  cmsg->cmsg_type = type;
+  cmsg->cmsg_len = CMSG_LEN(length);
+
+  msg->msg_controllen += cmsg_space;
+
+  return CMSG_DATA(cmsg);
+}
+
+/* ================================================== */
+
+static int
+send_message(int sock_fd, SCK_Message *message, int flags)
+{
+  struct cmsghdr cmsg_buf[CMSG_BUF_SIZE / sizeof (struct cmsghdr)];
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+  struct msghdr msg;
+  struct iovec iov;
+
+  switch (message->addr_type) {
+    case SCK_ADDR_UNSPEC:
+      saddr_len = 0;
+      break;
+    case SCK_ADDR_IP:
+      saddr_len = SCK_IPSockAddrToSockaddr(&message->remote_addr.ip,
+                                           (struct sockaddr *)&saddr, sizeof (saddr));
+      break;
+    case SCK_ADDR_UNIX:
+      memset(&saddr, 0, sizeof (saddr));
+      if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s",
+                   message->remote_addr.path) >= sizeof (saddr.un.sun_path)) {
+        DEBUG_LOG("Unix socket path %s too long", message->remote_addr.path);
+        return 0;
+      }
+      saddr.un.sun_family = AF_UNIX;
+      saddr_len = sizeof (saddr.un);
+      break;
+    default:
+      assert(0);
+  }
+
+  if (saddr_len) {
+    msg.msg_name = &saddr.un;
+    msg.msg_namelen = saddr_len;
+  } else {
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+  }
+
+  if (message->length < 0) {
+    DEBUG_LOG("Invalid length %d", message->length);
+    return 0;
+  }
+
+  iov.iov_base = message->data;
+  iov.iov_len = message->length;
+  msg.msg_iov = &iov;
+  msg.msg_iovlen = 1;
+  msg.msg_control = cmsg_buf;
+  msg.msg_controllen = 0;
+  msg.msg_flags = 0;
+
+  if (message->addr_type == SCK_ADDR_IP) {
+    if (message->local_addr.ip.family == IPADDR_INET4) {
+#ifdef HAVE_IN_PKTINFO
+      struct in_pktinfo *ipi;
+
+      ipi = add_control_message(&msg, IPPROTO_IP, IP_PKTINFO, sizeof (*ipi),
+                                sizeof (cmsg_buf));
+      if (!ipi)
+        return 0;
+
+      ipi->ipi_spec_dst.s_addr = htonl(message->local_addr.ip.addr.in4);
+      if (message->if_index != INVALID_IF_INDEX)
+        ipi->ipi_ifindex = message->if_index;
+
+#elif defined(IP_SENDSRCADDR)
+      struct in_addr *addr;
+
+      addr = add_control_message(&msg, IPPROTO_IP, IP_SENDSRCADDR, sizeof (*addr),
+                                 sizeof (cmsg_buf));
+      if (!addr)
+        return 0;
+
+      addr->s_addr = htonl(message->local_addr.ip.addr.in4);
+#endif
+    }
+
+#ifdef HAVE_IN6_PKTINFO
+    if (message->local_addr.ip.family == IPADDR_INET6) {
+      struct in6_pktinfo *ipi;
+
+      ipi = add_control_message(&msg, IPPROTO_IPV6, IPV6_PKTINFO, sizeof (*ipi),
+                                sizeof (cmsg_buf));
+      if (!ipi)
+        return 0;
+
+      memcpy(&ipi->ipi6_addr.s6_addr, &message->local_addr.ip.addr.in6,
+             sizeof(ipi->ipi6_addr.s6_addr));
+      if (message->if_index != INVALID_IF_INDEX)
+        ipi->ipi6_ifindex = message->if_index;
+    }
+#endif
+  }
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (message->timestamp.tx_flags) {
+    int *ts_tx_flags;
+
+    /* Set timestamping flags for this message */
+
+    ts_tx_flags = add_control_message(&msg, SOL_SOCKET, SO_TIMESTAMPING,
+                                      sizeof (*ts_tx_flags), sizeof (cmsg_buf));
+    if (!ts_tx_flags)
+      return 0;
+
+    *ts_tx_flags = message->timestamp.tx_flags;
+  }
+#endif
+
+  if (flags & SCK_FLAG_MSG_DESCRIPTOR) {
+    int *fd;
+
+    fd = add_control_message(&msg, SOL_SOCKET, SCM_RIGHTS, sizeof (*fd), sizeof (cmsg_buf));
+    if (!fd)
+      return 0;
+
+    *fd = message->descriptor;
+  }
+
+  /* This is apparently required on some systems */
+  if (msg.msg_controllen == 0)
+    msg.msg_control = NULL;
+
+  if (sendmsg(sock_fd, &msg, 0) < 0) {
+    log_message(sock_fd, -1, message, "Could not send", strerror(errno));
+    return 0;
+  }
+
+  log_message(sock_fd, -1, message, "Sent", NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SCK_Initialise(int family)
+{
+  ip4_enabled = family == IPADDR_INET4 || family == IPADDR_UNSPEC;
+#ifdef FEAT_IPV6
+  ip6_enabled = family == IPADDR_INET6 || family == IPADDR_UNSPEC;
+#else
+  ip6_enabled = 0;
+#endif
+
+  recv_messages = ARR_CreateInstance(sizeof (struct Message));
+  ARR_SetSize(recv_messages, MAX_RECV_MESSAGES);
+  recv_headers = ARR_CreateInstance(sizeof (struct MessageHeader));
+  ARR_SetSize(recv_headers, MAX_RECV_MESSAGES);
+  recv_sck_messages = ARR_CreateInstance(sizeof (SCK_Message));
+  ARR_SetSize(recv_sck_messages, MAX_RECV_MESSAGES);
+
+  received_messages = MAX_RECV_MESSAGES;
+
+  priv_bind_function = NULL;
+
+  supported_socket_flags = 0;
+#ifdef SOCK_CLOEXEC
+  if (check_socket_flag(SOCK_CLOEXEC, FD_CLOEXEC, 0))
+    supported_socket_flags |= SOCK_CLOEXEC;
+#endif
+#ifdef SOCK_NONBLOCK
+  if (check_socket_flag(SOCK_NONBLOCK, 0, O_NONBLOCK))
+    supported_socket_flags |= SOCK_NONBLOCK;
+#endif
+
+  initialised = 1;
+}
+
+/* ================================================== */
+
+void
+SCK_Finalise(void)
+{
+  ARR_DestroyInstance(recv_sck_messages);
+  ARR_DestroyInstance(recv_headers);
+  ARR_DestroyInstance(recv_messages);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+int
+SCK_IsIpFamilyEnabled(int family)
+{
+  switch (family) {
+    case IPADDR_INET4:
+      return ip4_enabled;
+    case IPADDR_INET6:
+      return ip6_enabled;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_GetAnyLocalIPAddress(int family, IPAddr *local_addr)
+{
+  local_addr->family = family;
+
+  switch (family) {
+    case IPADDR_INET4:
+      local_addr->addr.in4 = INADDR_ANY;
+      break;
+    case IPADDR_INET6:
+#ifdef FEAT_IPV6
+      memcpy(&local_addr->addr.in6, &in6addr_any, sizeof (local_addr->addr.in6));
+#else
+      memset(&local_addr->addr.in6, 0, sizeof (local_addr->addr.in6));
+#endif
+      break;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_GetLoopbackIPAddress(int family, IPAddr *local_addr)
+{
+  local_addr->family = family;
+
+  switch (family) {
+    case IPADDR_INET4:
+      local_addr->addr.in4 = INADDR_LOOPBACK;
+      break;
+    case IPADDR_INET6:
+#ifdef FEAT_IPV6
+      memcpy(&local_addr->addr.in6, &in6addr_loopback, sizeof (local_addr->addr.in6));
+#else
+      memset(&local_addr->addr.in6, 0, sizeof (local_addr->addr.in6));
+      local_addr->addr.in6[15] = 1;
+#endif
+      break;
+  }
+}
+
+/* ================================================== */
+
+int
+SCK_IsLinkLocalIPAddress(IPAddr *addr)
+{
+  switch (addr->family) {
+    case IPADDR_INET4:
+      /* 169.254.0.0/16 */
+      return (addr->addr.in4 & 0xffff0000) == 0xa9fe0000;
+    case IPADDR_INET6:
+      /* fe80::/10 */
+      return addr->addr.in6[0] == 0xfe && (addr->addr.in6[1] & 0xc0) == 0x80;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_SetPrivBind(int (*function)(int sock_fd, struct sockaddr *address,
+                                socklen_t address_len))
+{
+  priv_bind_function = function;
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUdpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface, int flags)
+{
+  return open_ip_socket(remote_addr, local_addr, iface, SOCK_DGRAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenTcpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface, int flags)
+{
+  return open_ip_socket(remote_addr, local_addr, iface, SOCK_STREAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixDatagramSocket(const char *remote_addr, const char *local_addr, int flags)
+{
+  return open_unix_socket(remote_addr, local_addr, SOCK_DGRAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixStreamSocket(const char *remote_addr, const char *local_addr, int flags)
+{
+  return open_unix_socket(remote_addr, local_addr, SOCK_STREAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixSocketPair(int flags, int *other_fd)
+{
+  int sock_fd;
+
+  /* Prefer SEQPACKET sockets over DGRAM in order to receive a zero-length
+     message (end of file) when the other end is unexpectedly closed */
+  if (
+#ifdef SOCK_SEQPACKET
+      (sock_fd = open_unix_socket_pair(SOCK_SEQPACKET, flags, other_fd)) < 0 &&
+#endif
+      (sock_fd = open_unix_socket_pair(SOCK_DGRAM, flags, other_fd)) < 0)
+    return INVALID_SOCK_FD;
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+int
+SCK_SetIntOption(int sock_fd, int level, int name, int value)
+{
+  if (setsockopt(sock_fd, level, name, &value, sizeof (value)) < 0) {
+    DEBUG_LOG("setsockopt() failed fd=%d level=%d name=%d value=%d : %s",
+              sock_fd, level, name, value, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_GetIntOption(int sock_fd, int level, int name, int *value)
+{
+  socklen_t len = sizeof (*value);
+
+  if (getsockopt(sock_fd, level, name, value, &len) < 0) {
+    DEBUG_LOG("getsockopt() failed fd=%d level=%d name=%d : %s",
+              sock_fd, level, name, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_EnableKernelRxTimestamping(int sock_fd)
+{
+#ifdef SO_TIMESTAMPNS
+  if (SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, 1))
+    return 1;
+#endif
+#ifdef SO_TIMESTAMP
+  if (SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMP, 1))
+    return 1;
+#endif
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+SCK_ListenOnSocket(int sock_fd, int backlog)
+{
+  if (listen(sock_fd, backlog) < 0) {
+    DEBUG_LOG("listen() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_AcceptConnection(int sock_fd, IPSockAddr *remote_addr)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len = sizeof (saddr);
+  int conn_fd;
+
+  conn_fd = accept(sock_fd, &saddr.sa, &saddr_len);
+  if (conn_fd < 0) {
+    DEBUG_LOG("accept() failed : %s", strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!UTI_FdSetCloexec(conn_fd) || !set_socket_nonblock(conn_fd)) {
+    close(conn_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  SCK_SockaddrToIPSockAddr(&saddr.sa, saddr_len, remote_addr);
+
+  return conn_fd;
+}
+
+/* ================================================== */
+
+int
+SCK_ShutdownConnection(int sock_fd)
+{
+  if (shutdown(sock_fd, SHUT_RDWR) < 0) {
+    DEBUG_LOG("shutdown() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_Receive(int sock_fd, void *buffer, int length, int flags)
+{
+  int r;
+
+  if (length < 0) {
+    DEBUG_LOG("Invalid length %d", length);
+    return -1;
+  }
+
+  r = recv(sock_fd, buffer, length, get_recv_flags(flags));
+
+  if (r < 0) {
+    handle_recv_error(sock_fd, flags);
+    return r;
+  }
+
+  DEBUG_LOG("Received data fd=%d len=%d", sock_fd, r);
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+SCK_Send(int sock_fd, const void *buffer, int length, int flags)
+{
+  int r;
+
+  assert(flags == 0);
+
+  if (length < 0) {
+    DEBUG_LOG("Invalid length %d", length);
+    return -1;
+  }
+
+  r = send(sock_fd, buffer, length, 0);
+
+  if (r < 0) {
+    DEBUG_LOG("Could not send data fd=%d len=%d : %s", sock_fd, length, strerror(errno));
+    return r;
+  }
+
+  DEBUG_LOG("Sent data fd=%d len=%d", sock_fd, r);
+
+  return r;
+}
+
+/* ================================================== */
+
+SCK_Message *
+SCK_ReceiveMessage(int sock_fd, int flags)
+{
+  int num_messages;
+
+  return receive_messages(sock_fd, flags, 1, &num_messages);
+}
+
+/* ================================================== */
+
+SCK_Message *
+SCK_ReceiveMessages(int sock_fd, int flags, int *num_messages)
+{
+  return receive_messages(sock_fd, flags, MAX_RECV_MESSAGES, num_messages);
+}
+
+/* ================================================== */
+
+void
+SCK_InitMessage(SCK_Message *message, SCK_AddressType addr_type)
+{
+  init_message_addresses(message, addr_type);
+  init_message_nonaddress(message);
+}
+
+/* ================================================== */
+
+int
+SCK_SendMessage(int sock_fd, SCK_Message *message, int flags)
+{
+  return send_message(sock_fd, message, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_RemoveSocket(int sock_fd)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+
+  saddr_len = sizeof (saddr);
+
+  if (getsockname(sock_fd, &saddr.sa, &saddr_len) < 0) {
+    DEBUG_LOG("getsockname() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  if (saddr_len > sizeof (saddr) || saddr_len <= sizeof (saddr.sa.sa_family) ||
+      saddr.sa.sa_family != AF_UNIX)
+    return 0;
+
+  if (unlink(saddr.un.sun_path) < 0) {
+    DEBUG_LOG("Could not remove %s : %s", saddr.un.sun_path, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SCK_CloseSocket(int sock_fd)
+{
+  close(sock_fd);
+}
+
+/* ================================================== */
+
+void
+SCK_SockaddrToIPSockAddr(struct sockaddr *sa, int sa_length, IPSockAddr *ip_sa)
+{
+  ip_sa->ip_addr.family = IPADDR_UNSPEC;
+  ip_sa->port = 0;
+
+  switch (sa->sa_family) {
+    case AF_INET:
+      if (sa_length < (int)sizeof (struct sockaddr_in))
+        return;
+      ip_sa->ip_addr.family = IPADDR_INET4;
+      ip_sa->ip_addr.addr.in4 = ntohl(((struct sockaddr_in *)sa)->sin_addr.s_addr);
+      ip_sa->port = ntohs(((struct sockaddr_in *)sa)->sin_port);
+      break;
+#ifdef FEAT_IPV6
+    case AF_INET6:
+      if (sa_length < (int)sizeof (struct sockaddr_in6))
+        return;
+      ip_sa->ip_addr.family = IPADDR_INET6;
+      memcpy(&ip_sa->ip_addr.addr.in6, ((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr,
+             sizeof (ip_sa->ip_addr.addr.in6));
+      ip_sa->port = ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
+      break;
+#endif
+    default:
+      break;
+  }
+}
+
+/* ================================================== */
+
+int
+SCK_IPSockAddrToSockaddr(IPSockAddr *ip_sa, struct sockaddr *sa, int sa_length)
+{
+  switch (ip_sa->ip_addr.family) {
+    case IPADDR_INET4:
+      if (sa_length < (int)sizeof (struct sockaddr_in))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr_in));
+      sa->sa_family = AF_INET;
+      ((struct sockaddr_in *)sa)->sin_addr.s_addr = htonl(ip_sa->ip_addr.addr.in4);
+      ((struct sockaddr_in *)sa)->sin_port = htons(ip_sa->port);
+#ifdef SIN6_LEN
+      ((struct sockaddr_in *)sa)->sin_len = sizeof (struct sockaddr_in);
+#endif
+      return sizeof (struct sockaddr_in);
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      if (sa_length < (int)sizeof (struct sockaddr_in6))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr_in6));
+      sa->sa_family = AF_INET6;
+      memcpy(&((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr, ip_sa->ip_addr.addr.in6,
+             sizeof (((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr));
+      ((struct sockaddr_in6 *)sa)->sin6_port = htons(ip_sa->port);
+#ifdef SIN6_LEN
+      ((struct sockaddr_in6 *)sa)->sin6_len = sizeof (struct sockaddr_in6);
+#endif
+      return sizeof (struct sockaddr_in6);
+#endif
+    default:
+      if (sa_length < (int)sizeof (struct sockaddr))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr));
+      sa->sa_family = AF_UNSPEC;
+      return 0;
+  }
+}
diff --git a/socket.h b/socket.h
new file mode 100644
index 0000000..cdbae2d
--- /dev/null
+++ b/socket.h
@@ -0,0 +1,147 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for socket operations.
+
+  */
+
+#ifndef GOT_SOCKET_H
+#define GOT_SOCKET_H
+
+#include "addressing.h"
+
+/* Flags for opening sockets */
+#define SCK_FLAG_BLOCK 1
+#define SCK_FLAG_BROADCAST 2
+#define SCK_FLAG_RX_DEST_ADDR 4
+#define SCK_FLAG_ALL_PERMISSIONS 8
+#define SCK_FLAG_PRIV_BIND 16
+
+/* Flags for receiving and sending messages */
+#define SCK_FLAG_MSG_ERRQUEUE 1
+#define SCK_FLAG_MSG_DESCRIPTOR 2
+
+typedef enum {
+  SCK_ADDR_UNSPEC = 0,
+  SCK_ADDR_IP,
+  SCK_ADDR_UNIX
+} SCK_AddressType;
+
+typedef struct {
+  void *data;
+  int length;
+  SCK_AddressType addr_type;
+  int if_index;
+
+  union {
+    IPSockAddr ip;
+    const char *path;
+  } remote_addr;
+
+  union {
+    IPAddr ip;
+  } local_addr;
+
+  struct {
+    struct timespec kernel;
+    struct timespec hw;
+    int if_index;
+    int l2_length;
+    int tx_flags;
+  } timestamp;
+
+  int descriptor;
+} SCK_Message;
+
+/* Initialisation function (the specified IP family is enabled,
+   or all if IPADDR_UNSPEC) */
+extern void SCK_Initialise(int family);
+
+/* Finalisation function */
+extern void SCK_Finalise(void);
+
+/* Check if support for the IP family is enabled */
+extern int SCK_IsIpFamilyEnabled(int family);
+
+/* Get the 0.0.0.0/::0 or 127.0.0.1/::1 address */
+extern void SCK_GetAnyLocalIPAddress(int family, IPAddr *local_addr);
+extern void SCK_GetLoopbackIPAddress(int family, IPAddr *local_addr);
+
+/* Check if an IP address is a link-local address */
+extern int SCK_IsLinkLocalIPAddress(IPAddr *addr);
+
+/* Specify a bind()-like function for binding sockets to privileged ports when
+   running in a restricted process (e.g. after dropping root privileges) */
+extern void SCK_SetPrivBind(int (*function)(int sock_fd, struct sockaddr *address,
+                                            socklen_t address_len));
+
+/* Open a socket (addresses and iface may be NULL) */
+extern int SCK_OpenUdpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr,
+                             const char *iface, int flags);
+extern int SCK_OpenTcpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr,
+                             const char *iface, int flags);
+extern int SCK_OpenUnixDatagramSocket(const char *remote_addr, const char *local_addr,
+                                      int flags);
+extern int SCK_OpenUnixStreamSocket(const char *remote_addr, const char *local_addr,
+                                    int flags);
+extern int SCK_OpenUnixSocketPair(int flags, int *other_fd);
+
+/* Set and get a socket option of int size */
+extern int SCK_SetIntOption(int sock_fd, int level, int name, int value);
+extern int SCK_GetIntOption(int sock_fd, int level, int name, int *value);
+
+/* Enable RX timestamping socket option */
+extern int SCK_EnableKernelRxTimestamping(int sock_fd);
+
+/* Operate on a stream socket - listen()/accept()/shutdown() wrappers */
+extern int SCK_ListenOnSocket(int sock_fd, int backlog);
+extern int SCK_AcceptConnection(int sock_fd, IPSockAddr *remote_addr);
+extern int SCK_ShutdownConnection(int sock_fd);
+
+/* Receive and send data on connected sockets - recv()/send() wrappers */
+extern int SCK_Receive(int sock_fd, void *buffer, int length, int flags);
+extern int SCK_Send(int sock_fd, const void *buffer, int length, int flags);
+
+/* Receive a single message or multiple messages.  The functions return
+   a pointer to static buffers, or NULL on error.  The buffers are valid until
+   another call of the functions and can be reused for sending messages. */
+extern SCK_Message *SCK_ReceiveMessage(int sock_fd, int flags);
+extern SCK_Message *SCK_ReceiveMessages(int sock_fd, int flags, int *num_messages);
+
+/* Initialise a new message (e.g. before sending) */
+extern void SCK_InitMessage(SCK_Message *message, SCK_AddressType addr_type);
+
+/* Send a message */
+extern int SCK_SendMessage(int sock_fd, SCK_Message *message, int flags);
+
+/* Remove bound Unix socket */
+extern int SCK_RemoveSocket(int sock_fd);
+
+/* Close the socket */
+extern void SCK_CloseSocket(int sock_fd);
+
+/* Convert between IPSockAddr and sockaddr_in/in6 */
+extern void SCK_SockaddrToIPSockAddr(struct sockaddr *sa, int sa_length, IPSockAddr *ip_sa);
+extern int SCK_IPSockAddrToSockaddr(IPSockAddr *ip_sa, struct sockaddr *sa, int sa_length);
+
+#endif
diff --git a/sources.c b/sources.c
new file mode 100644
index 0000000..2aee6f2
--- /dev/null
+++ b/sources.c
@@ -0,0 +1,1756 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2016, 2018, 2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The routines in this file manage the complete pool of sources that
+  we might be synchronizing to.  This includes NTP sources and others
+  (e.g. local reference clocks, eyeball + wristwatch etc).
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sources.h"
+#include "sourcestats.h"
+#include "memory.h"
+#include "ntp.h" /* For NTP_Leap */
+#include "ntp_sources.h"
+#include "local.h"
+#include "reference.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "reports.h"
+#include "nameserv.h"
+#include "sched.h"
+#include "regress.h"
+
+/* ================================================== */
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* ================================================== */
+/* Structure used to hold info for selecting between sources */
+struct SelectInfo {
+  int select_ok;
+  double std_dev;
+  double root_distance;
+  double lo_limit;
+  double hi_limit;
+  double last_sample_ago;
+};
+
+/* ================================================== */
+/* This enum contains the flag values that are used to label
+   each source */
+typedef enum {
+  SRC_OK,               /* OK so far, not a final status! */
+  SRC_UNSELECTABLE,     /* Has noselect option set */
+  SRC_UNSYNCHRONISED,   /* Provides samples but not unsynchronised */
+  SRC_BAD_STATS,        /* Doesn't have valid stats data */
+  SRC_BAD_DISTANCE,     /* Has root distance longer than allowed maximum */
+  SRC_JITTERY,          /* Had std dev larger than allowed maximum */
+  SRC_WAITS_STATS,      /* Others have bad stats, selection postponed */
+  SRC_STALE,            /* Has older samples than others */
+  SRC_ORPHAN,           /* Has stratum equal or larger than orphan stratum */
+  SRC_UNTRUSTED,        /* Overlaps trusted sources */
+  SRC_FALSETICKER,      /* Doesn't agree with others */
+  SRC_WAITS_SOURCES,    /* Not enough sources, selection postponed */
+  SRC_NONPREFERRED,     /* Others have prefer option */
+  SRC_WAITS_UPDATE,     /* No updates, selection postponed */
+  SRC_DISTANT,          /* Others have shorter root distance */
+  SRC_OUTLIER,          /* Outlier in clustering (not used yet) */
+  SRC_UNSELECTED,       /* Used for synchronisation, not system peer */
+  SRC_SELECTED,         /* Used for synchronisation, selected as system peer */
+} SRC_Status;
+
+/* ================================================== */
+/* Define the instance structure used to hold information about each
+   source */
+struct SRC_Instance_Record {
+  SST_Stats stats;
+  int index;                    /* Index back into the array of source */
+  uint32_t ref_id;              /* The reference ID of this source
+                                   (i.e. from its IP address, NOT the
+                                   reference _it_ is sync'd to) */
+  IPAddr *ip_addr;              /* Its IP address if NTP source */
+
+  /* Flag indicating that the source is updating reachability */
+  int active;
+
+  /* Reachability register */
+  int reachability;
+
+  /* Number of set bits in the reachability register */
+  int reachability_size;
+
+  /* Updates since last reference update */
+  int updates;
+
+  /* Updates left before allowing combining */
+  int distant;
+
+  /* Flag indicating the status of the source */
+  SRC_Status status;
+
+  /* Type of the source */
+  SRC_Type type;
+
+  /* Flag indicating that the source is authenticated */
+  int authenticated;
+
+  /* Configured selection options */
+  int conf_sel_options;
+
+  /* Effective selection options */
+  int sel_options;
+
+  /* Score against currently selected source */
+  double sel_score;
+
+  struct SelectInfo sel_info;
+
+  /* Current stratum */
+  int stratum;
+
+  /* Current leap status */
+  NTP_Leap leap;
+
+  /* Flag indicating the source has a leap second vote */
+  int leap_vote;
+};
+
+/* ================================================== */
+/* Structure used to build the sort list for finding falsetickers */
+struct Sort_Element {
+  int index;
+  double offset;
+  enum {
+    LOW = -1,
+    HIGH = 1
+  } tag;
+};
+
+/* ================================================== */
+/* Table of sources */
+static struct SRC_Instance_Record **sources;
+static struct Sort_Element *sort_list;
+static int *sel_sources;
+static int n_sources; /* Number of sources currently in the table */
+static int max_n_sources; /* Capacity of the table */
+
+#define INVALID_SOURCE (-1)
+static int selected_source_index; /* Which source index is currently
+                                     selected (set to INVALID_SOURCE
+                                     if no current valid reference) */
+
+/* Score needed to replace the currently selected source */
+#define SCORE_LIMIT 10.0
+
+/* Number of updates needed to reset the distant status */
+#define DISTANT_PENALTY 32
+
+static double max_distance;
+static double max_jitter;
+static double reselect_distance;
+static double stratum_weight;
+static double combine_limit;
+
+static LOG_FileID logfileid;
+
+/* Identifier of the dump file */
+#define DUMP_IDENTIFIER "SRC0\n"
+
+/* ================================================== */
+/* Forward prototype */
+
+static void update_sel_options(void);
+static void slew_sources(struct timespec *raw, struct timespec *cooked, double dfreq,
+                         double doffset, LCL_ChangeType change_type, void *anything);
+static void add_dispersion(double dispersion, void *anything);
+static char *source_to_string(SRC_Instance inst);
+static char get_status_char(SRC_Status status);
+
+/* ================================================== */
+/* Initialisation function */
+void SRC_Initialise(void) {
+  sources = NULL;
+  sort_list = NULL;
+  sel_sources = NULL;
+  n_sources = 0;
+  max_n_sources = 0;
+  selected_source_index = INVALID_SOURCE;
+  max_distance = CNF_GetMaxDistance();
+  max_jitter = CNF_GetMaxJitter();
+  reselect_distance = CNF_GetReselectDistance();
+  stratum_weight = CNF_GetStratumWeight();
+  combine_limit = CNF_GetCombineLimit();
+  initialised = 1;
+
+  LCL_AddParameterChangeHandler(slew_sources, NULL);
+  LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
+
+  logfileid = CNF_GetLogSelection() ? LOG_FileOpen("selection",
+              "   Date (UTC) Time     IP Address   S EOpts Reach Score Last sample  Low end   High end")
+              : -1;
+}
+
+/* ================================================== */
+/* Finalisation function */
+void SRC_Finalise(void)
+{
+  LCL_RemoveParameterChangeHandler(slew_sources, NULL);
+  LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
+
+  Free(sources);
+  Free(sort_list);
+  Free(sel_sources);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+/* Function to create a new instance.  This would be called by one of
+   the individual source-type instance creation routines. */
+
+SRC_Instance SRC_CreateNewInstance(uint32_t ref_id, SRC_Type type, int authenticated,
+                                   int sel_options, IPAddr *addr, int min_samples,
+                                   int max_samples, double min_delay, double asymmetry)
+{
+  SRC_Instance result;
+
+  assert(initialised);
+
+  if (min_samples == SRC_DEFAULT_MINSAMPLES)
+    min_samples = CNF_GetMinSamples();
+  if (max_samples == SRC_DEFAULT_MAXSAMPLES)
+    max_samples = CNF_GetMaxSamples();
+
+  result = MallocNew(struct SRC_Instance_Record);
+  result->stats = SST_CreateInstance(ref_id, addr, min_samples, max_samples,
+                                     min_delay, asymmetry);
+
+  if (n_sources == max_n_sources) {
+    /* Reallocate memory */
+    max_n_sources = max_n_sources > 0 ? 2 * max_n_sources : 4;
+    if (sources) {
+      sources = ReallocArray(struct SRC_Instance_Record *, max_n_sources, sources);
+      sort_list = ReallocArray(struct Sort_Element, 3*max_n_sources, sort_list);
+      sel_sources = ReallocArray(int, max_n_sources, sel_sources);
+    } else {
+      sources = MallocArray(struct SRC_Instance_Record *, max_n_sources);
+      sort_list = MallocArray(struct Sort_Element, 3*max_n_sources);
+      sel_sources = MallocArray(int, max_n_sources);
+    }
+  }
+
+  sources[n_sources] = result;
+
+  result->index = n_sources;
+  result->type = type;
+  result->authenticated = authenticated;
+  result->conf_sel_options = sel_options;
+  result->sel_options = sel_options;
+  result->active = 0;
+
+  SRC_SetRefid(result, ref_id, addr);
+  SRC_ResetInstance(result);
+
+  n_sources++;
+
+  update_sel_options();
+
+  return result;
+}
+
+/* ================================================== */
+/* Function to get rid of a source when it is being unconfigured.
+   This may cause the current reference source to be reselected, if this
+   was the reference source or contributed significantly to a
+   falseticker decision. */
+
+void SRC_DestroyInstance(SRC_Instance instance)
+{
+  int dead_index, i;
+
+  assert(initialised);
+
+  SST_DeleteInstance(instance->stats);
+  dead_index = instance->index;
+  for (i=dead_index; i<n_sources-1; i++) {
+    sources[i] = sources[i+1];
+    sources[i]->index = i;
+  }
+  --n_sources;
+  Free(instance);
+
+  update_sel_options();
+
+  /* If this was the previous reference source, we have to reselect! */
+  if (selected_source_index == dead_index)
+    SRC_ReselectSource();
+  else if (selected_source_index > dead_index)
+    --selected_source_index;
+}
+
+/* ================================================== */
+
+void
+SRC_ResetInstance(SRC_Instance instance)
+{
+  instance->updates = 0;
+  instance->reachability = 0;
+  instance->reachability_size = 0;
+  instance->distant = 0;
+  instance->status = SRC_BAD_STATS;
+  instance->sel_score = 1.0;
+  instance->stratum = 0;
+  instance->leap = LEAP_Unsynchronised;
+  instance->leap_vote = 0;
+
+  memset(&instance->sel_info, 0, sizeof (instance->sel_info));
+
+  SST_ResetInstance(instance->stats);
+}
+
+/* ================================================== */
+
+void
+SRC_SetRefid(SRC_Instance instance, uint32_t ref_id, IPAddr *addr)
+{
+  instance->ref_id = ref_id;
+  instance->ip_addr = addr;
+  SST_SetRefid(instance->stats, ref_id, addr);
+}
+
+/* ================================================== */
+
+SST_Stats
+SRC_GetSourcestats(SRC_Instance instance)
+{
+  assert(initialised);
+  return instance->stats;
+}
+
+/* ================================================== */
+
+static NTP_Leap
+get_leap_status(void)
+{
+  int i, leap_votes, leap_ins, leap_del;
+
+  /* Accept a leap second if more than half of the sources with a vote agree */
+
+  for (i = leap_ins = leap_del = leap_votes = 0; i < n_sources; i++) {
+    if (!sources[i]->leap_vote)
+      continue;
+
+    leap_votes++;
+    if (sources[i]->leap == LEAP_InsertSecond)
+      leap_ins++;
+    else if (sources[i]->leap == LEAP_DeleteSecond)
+      leap_del++;
+  }
+
+  if (leap_ins > leap_votes / 2)
+    return LEAP_InsertSecond;
+  else if (leap_del > leap_votes / 2)
+    return LEAP_DeleteSecond;
+  else
+    return LEAP_Normal;
+}
+
+/* ================================================== */
+
+void
+SRC_UpdateStatus(SRC_Instance inst, int stratum, NTP_Leap leap)
+{
+  inst->stratum = stratum;
+
+  if (REF_IsLeapSecondClose(NULL, 0.0))
+    return;
+
+  inst->leap = leap;
+
+  if (inst->leap_vote)
+    REF_UpdateLeapStatus(get_leap_status());
+}
+
+/* ================================================== */
+
+/* This function is called by one of the source drivers when it has
+   a new sample that is to be accumulated.
+
+   This function causes the frequency estimation to be re-run for the
+   designated source, and the clock selection procedure to be re-run
+   afterwards.
+   */
+
+void
+SRC_AccumulateSample(SRC_Instance inst, NTP_Sample *sample)
+{
+
+  assert(initialised);
+
+  DEBUG_LOG("src=%s ts=%s offset=%e delay=%e disp=%e",
+            source_to_string(inst), UTI_TimespecToString(&sample->time), -sample->offset,
+            sample->root_delay, sample->root_dispersion);
+
+  if (REF_IsLeapSecondClose(&sample->time, sample->offset)) {
+    LOG(LOGS_INFO, "Dropping sample around leap second");
+    return;
+  }
+
+  SST_AccumulateSample(inst->stats, sample);
+  SST_DoNewRegression(inst->stats);
+}
+
+/* ================================================== */
+
+void
+SRC_SetActive(SRC_Instance inst)
+{
+  inst->active = 1;
+}
+
+/* ================================================== */
+
+void
+SRC_UnsetActive(SRC_Instance inst)
+{
+  inst->active = 0;
+}
+
+/* ================================================== */
+
+static int
+special_mode_end(void)
+{
+    int i;
+
+    for (i = 0; i < n_sources; i++) {
+      /* No updates from inactive sources */
+      if (!sources[i]->active)
+        continue;
+
+      /* Don't expect more updates than the initial burst of an NTP source */
+      if (sources[i]->reachability_size >= SOURCE_REACH_BITS - 1)
+        continue;
+
+      /* Check if the source could still have enough samples to be selectable */
+      if (SOURCE_REACH_BITS - 1 - sources[i]->reachability_size +
+            SST_Samples(sources[i]->stats) >= MIN_SAMPLES_FOR_REGRESS)
+        return 0;
+    }
+
+    return 1;
+}
+
+void
+SRC_UpdateReachability(SRC_Instance inst, int reachable)
+{
+  inst->reachability <<= 1;
+  inst->reachability |= !!reachable;
+  inst->reachability %= 1U << SOURCE_REACH_BITS;
+
+  if (inst->reachability_size < SOURCE_REACH_BITS)
+      inst->reachability_size++;
+
+  if (!reachable && inst->index == selected_source_index) {
+    /* Try to select a better source */
+    SRC_SelectSource(NULL);
+  }
+
+  /* Check if special reference update mode failed */
+  if (REF_GetMode() != REF_ModeNormal && special_mode_end()) {
+    REF_SetUnsynchronised();
+  }
+
+  /* Try to replace NTP sources that are unreachable, falsetickers, or
+     have root distance or jitter larger than the allowed maximums */
+  if (inst->type == SRC_NTP &&
+      ((!inst->reachability && inst->reachability_size == SOURCE_REACH_BITS) ||
+       inst->status == SRC_BAD_DISTANCE || inst->status == SRC_JITTERY ||
+       inst->status == SRC_FALSETICKER)) {
+    NSR_HandleBadSource(inst->ip_addr);
+  }
+}
+
+/* ================================================== */
+
+void
+SRC_ResetReachability(SRC_Instance inst)
+{
+  inst->reachability = 0;
+  inst->reachability_size = 0;
+  SRC_UpdateReachability(inst, 0);
+}
+
+/* ================================================== */
+
+static void
+update_sel_options(void)
+{
+  int options, auth_ntp_options, unauth_ntp_options, refclk_options;
+  int i, auth_ntp_sources, unauth_ntp_sources;
+
+  auth_ntp_sources = unauth_ntp_sources = 0;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->conf_sel_options & SRC_SELECT_NOSELECT)
+      continue;
+    if (sources[i]->type != SRC_NTP)
+      continue;
+    if (sources[i]->authenticated)
+      auth_ntp_sources++;
+    else
+      unauth_ntp_sources++;
+  }
+
+  auth_ntp_options = unauth_ntp_options = refclk_options = 0;
+
+  /* Determine which selection options need to be added to authenticated NTP
+     sources, unauthenticated NTP sources, and refclocks, to follow the
+     configured selection mode */
+  switch (CNF_GetAuthSelectMode()) {
+    case SRC_AUTHSELECT_IGNORE:
+      break;
+    case SRC_AUTHSELECT_MIX:
+      if (auth_ntp_sources > 0 && unauth_ntp_sources > 0)
+        auth_ntp_options = refclk_options = SRC_SELECT_REQUIRE | SRC_SELECT_TRUST;
+      break;
+    case SRC_AUTHSELECT_PREFER:
+      if (auth_ntp_sources > 0)
+        unauth_ntp_options = SRC_SELECT_NOSELECT;
+      break;
+    case SRC_AUTHSELECT_REQUIRE:
+      unauth_ntp_options = SRC_SELECT_NOSELECT;
+      break;
+    default:
+      assert(0);
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    options = sources[i]->conf_sel_options;
+
+    if (options & SRC_SELECT_NOSELECT)
+      continue;
+
+    switch (sources[i]->type) {
+      case SRC_NTP:
+        options |= sources[i]->authenticated ? auth_ntp_options : unauth_ntp_options;
+        break;
+      case SRC_REFCLOCK:
+        options |= refclk_options;
+        break;
+      default:
+        assert(0);
+    }
+
+    if (sources[i]->sel_options != options) {
+      DEBUG_LOG("changing %s from %x to %x", source_to_string(sources[i]),
+                (unsigned int)sources[i]->sel_options, (unsigned int)options);
+      sources[i]->sel_options = options;
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+log_selection_message(const char *format, const char *arg)
+{
+  if (REF_GetMode() != REF_ModeNormal)
+    return;
+  LOG(LOGS_INFO, format, arg);
+}
+
+/* ================================================== */
+
+static void
+log_selection_source(const char *format, SRC_Instance inst)
+{
+  char buf[320], *name, *ntp_name;
+
+  name = source_to_string(inst);
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : NULL;
+
+  if (ntp_name && strcmp(name, ntp_name) != 0)
+    snprintf(buf, sizeof (buf), "%s (%s)", name, ntp_name);
+  else
+    snprintf(buf, sizeof (buf), "%s", name);
+
+  log_selection_message(format, buf);
+}
+
+/* ================================================== */
+
+static int
+compare_sort_elements(const void *a, const void *b)
+{
+  const struct Sort_Element *u = (const struct Sort_Element *) a;
+  const struct Sort_Element *v = (const struct Sort_Element *) b;
+
+  if (u->offset < v->offset) {
+    return -1;
+  } else if (u->offset > v->offset) {
+    return +1;
+  } else if (u->tag < v->tag) {
+    return -1;
+  } else if (u->tag > v->tag) {
+    return +1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static char *
+source_to_string(SRC_Instance inst)
+{
+  switch (inst->type) {
+    case SRC_NTP:
+      return UTI_IPToString(inst->ip_addr);
+    case SRC_REFCLOCK:
+      return UTI_RefidToString(inst->ref_id);
+    default:
+      assert(0);
+  }
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+mark_source(SRC_Instance inst, SRC_Status status)
+{
+  struct timespec now;
+
+  inst->status = status;
+
+  DEBUG_LOG("%s status=%c options=%x reach=%o/%d updates=%d distant=%d leap=%d vote=%d lo=%f hi=%f",
+            source_to_string(inst), get_status_char(inst->status),
+            (unsigned int)inst->sel_options, (unsigned int)inst->reachability,
+            inst->reachability_size, inst->updates,
+            inst->distant, (int)inst->leap, inst->leap_vote,
+            inst->sel_info.lo_limit, inst->sel_info.hi_limit);
+
+  if (logfileid == -1)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  LOG_FileWrite(logfileid,
+                "%s %-15s %c -%c%c%c%c %4o %5.2f %10.3e %10.3e %10.3e",
+                UTI_TimeToLogForm(now.tv_sec), source_to_string(inst),
+                get_status_char(inst->status),
+                inst->sel_options & SRC_SELECT_NOSELECT ? 'N' : '-',
+                inst->sel_options & SRC_SELECT_PREFER ? 'P' : '-',
+                inst->sel_options & SRC_SELECT_TRUST ? 'T' : '-',
+                inst->sel_options & SRC_SELECT_REQUIRE ? 'R' : '-',
+                (unsigned int)inst->reachability, inst->sel_score,
+                inst->sel_info.last_sample_ago,
+                inst->sel_info.lo_limit, inst->sel_info.hi_limit);
+}
+
+/* ================================================== */
+
+static void
+mark_ok_sources(SRC_Status status)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+    mark_source(sources[i], status);
+  }
+}
+
+/* ================================================== */
+
+static int
+combine_sources(int n_sel_sources, struct timespec *ref_time, double *offset,
+                double *offset_sd, double *frequency, double *frequency_sd, double *skew)
+{
+  struct timespec src_ref_time;
+  double src_offset, src_offset_sd, src_frequency, src_frequency_sd, src_skew;
+  double src_root_delay, src_root_dispersion, sel_src_distance, elapsed;
+  double offset_weight, sum_offset_weight, sum_offset, sum2_offset_sd;
+  double frequency_weight, sum_frequency_weight, sum_frequency;
+  double inv_sum2_frequency_sd, inv_sum2_skew;
+  int i, index, combined;
+
+  if (n_sel_sources == 1)
+    return 1;
+
+  sum_offset_weight = sum_offset = sum2_offset_sd = 0.0;
+  sum_frequency_weight = sum_frequency = inv_sum2_frequency_sd = inv_sum2_skew = 0.0;
+
+  sel_src_distance = sources[selected_source_index]->sel_info.root_distance;
+  if (sources[selected_source_index]->type == SRC_NTP)
+    sel_src_distance += reselect_distance;
+
+  for (i = combined = 0; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    SST_GetTrackingData(sources[index]->stats, &src_ref_time,
+                        &src_offset, &src_offset_sd,
+                        &src_frequency, &src_frequency_sd, &src_skew,
+                        &src_root_delay, &src_root_dispersion);
+
+    /* Don't include this source if its distance is longer than the distance of
+       the selected source multiplied by the limit, their estimated frequencies
+       are not close, or it was recently marked as distant */
+
+    if (index != selected_source_index &&
+        (sources[index]->sel_info.root_distance > combine_limit * sel_src_distance ||
+         fabs(*frequency - src_frequency) >
+           combine_limit * (*skew + src_skew + LCL_GetMaxClockError()))) {
+      /* Use a smaller penalty in first few updates */
+      sources[index]->distant = sources[index]->reachability_size >= SOURCE_REACH_BITS ?
+                                DISTANT_PENALTY : 1;
+    } else if (sources[index]->distant) {
+      sources[index]->distant--;
+    }
+
+    if (sources[index]->distant) {
+      mark_source(sources[index], SRC_DISTANT);
+      continue;
+    }
+
+    if (sources[index]->status == SRC_OK)
+      mark_source(sources[index], SRC_UNSELECTED);
+
+    elapsed = UTI_DiffTimespecsToDouble(ref_time, &src_ref_time);
+    src_offset += elapsed * src_frequency;
+    src_offset_sd += elapsed * src_frequency_sd;
+    offset_weight = 1.0 / sources[index]->sel_info.root_distance;
+    frequency_weight = 1.0 / SQUARE(src_frequency_sd);
+
+    DEBUG_LOG("combining %s oweight=%e offset=%e osd=%e fweight=%e freq=%e fsd=%e skew=%e",
+              source_to_string(sources[index]), offset_weight, src_offset, src_offset_sd,
+              frequency_weight, src_frequency, src_frequency_sd, src_skew);
+
+    sum_offset_weight += offset_weight;
+    sum_offset += offset_weight * src_offset;
+    sum2_offset_sd += offset_weight * (SQUARE(src_offset_sd) +
+                                       SQUARE(src_offset - *offset));
+
+    sum_frequency_weight += frequency_weight;
+    sum_frequency += frequency_weight * src_frequency;
+    inv_sum2_frequency_sd += 1.0 / SQUARE(src_frequency_sd);
+    inv_sum2_skew += 1.0 / SQUARE(src_skew);
+
+    combined++;
+  }
+
+  assert(combined);
+  *offset = sum_offset / sum_offset_weight;
+  *offset_sd = sqrt(sum2_offset_sd / sum_offset_weight);
+  *frequency = sum_frequency / sum_frequency_weight;
+  *frequency_sd = 1.0 / sqrt(inv_sum2_frequency_sd);
+  *skew = 1.0 / sqrt(inv_sum2_skew);
+
+  DEBUG_LOG("combined result offset=%e osd=%e freq=%e fsd=%e skew=%e",
+            *offset, *offset_sd, *frequency, *frequency_sd, *skew);
+
+  return combined;
+}
+
+/* ================================================== */
+/* This function selects the current reference from amongst the pool
+   of sources we are holding and updates the local reference */
+
+void
+SRC_SelectSource(SRC_Instance updated_inst)
+{
+  struct SelectInfo *si;
+  struct timespec now, ref_time;
+  int i, j, j1, j2, index, sel_prefer, n_endpoints, n_sel_sources, sel_req_source;
+  int n_badstats_sources, max_sel_reach, max_sel_reach_size, max_badstat_reach;
+  int depth, best_depth, trust_depth, best_trust_depth, n_sel_trust_sources;
+  int combined, stratum, min_stratum, max_score_index;
+  int orphan_stratum, orphan_source;
+  double src_offset, src_offset_sd, src_frequency, src_frequency_sd, src_skew;
+  double src_root_delay, src_root_dispersion;
+  double best_lo, best_hi, distance, sel_src_distance, max_score;
+  double best_trust_lo, best_trust_hi;
+  double first_sample_ago, max_reach_sample_ago;
+  NTP_Leap leap_status;
+
+  if (updated_inst)
+    updated_inst->updates++;
+
+  if (n_sources == 0) {
+    /* In this case, we clearly cannot synchronise to anything */
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message("Can't synchronise: no sources", NULL);
+      selected_source_index = INVALID_SOURCE;
+    }
+    return;
+  }
+
+  /* This is accurate enough and cheaper than calling LCL_ReadCookedTime */
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  /* Step 1 - build intervals about each source */
+
+  n_endpoints = 0;
+  n_sel_sources = n_sel_trust_sources = 0;
+  n_badstats_sources = 0;
+  sel_req_source = 0;
+  max_sel_reach = max_badstat_reach = 0;
+  max_sel_reach_size = 0;
+  max_reach_sample_ago = 0.0;
+
+  for (i = 0; i < n_sources; i++) {
+    assert(sources[i]->status != SRC_OK);
+
+    /* Don't allow the source to vote on leap seconds unless it's selectable */
+    sources[i]->leap_vote = 0;
+
+    /* If some sources are specified with the require option, at least one
+       of them will have to be selectable in order to update the clock */
+    if (sources[i]->sel_options & SRC_SELECT_REQUIRE)
+      sel_req_source = 1;
+
+    /* Ignore sources which were added with the noselect option */
+    if (sources[i]->sel_options & SRC_SELECT_NOSELECT) {
+      mark_source(sources[i], SRC_UNSELECTABLE);
+      continue;
+    }
+
+    /* Ignore sources which are not synchronised */
+    if (sources[i]->leap == LEAP_Unsynchronised) {
+      mark_source(sources[i], SRC_UNSYNCHRONISED);
+      continue;
+    }
+
+    si = &sources[i]->sel_info;
+    SST_GetSelectionData(sources[i]->stats, &now,
+                         &si->lo_limit, &si->hi_limit, &si->root_distance,
+                         &si->std_dev, &first_sample_ago,
+                         &si->last_sample_ago, &si->select_ok);
+
+    if (!si->select_ok) {
+      ++n_badstats_sources;
+      mark_source(sources[i], SRC_BAD_STATS);
+      if (max_badstat_reach < sources[i]->reachability)
+        max_badstat_reach = sources[i]->reachability;
+      continue;
+    }
+
+    /* Include extra dispersion in the root distance of sources that don't
+       have new samples (the last sample is older than span of all samples) */
+    if (first_sample_ago < 2.0 * si->last_sample_ago) {
+      double extra_disp = LCL_GetMaxClockError() *
+                          (2.0 * si->last_sample_ago - first_sample_ago);
+      si->root_distance += extra_disp;
+      si->lo_limit -= extra_disp;
+      si->hi_limit += extra_disp;
+    }
+
+    /* Require the root distance to be below the allowed maximum and the
+       endpoints to be in the right order (i.e. a non-negative distance) */
+    if (!(si->root_distance <= max_distance && si->lo_limit <= si->hi_limit)) {
+      mark_source(sources[i], SRC_BAD_DISTANCE);
+      continue;
+    }
+
+    /* And the same applies for the estimated standard deviation */
+    if (si->std_dev > max_jitter) {
+      mark_source(sources[i], SRC_JITTERY);
+      continue;
+    }
+
+    sources[i]->status = SRC_OK; /* For now */
+
+    if (sources[i]->reachability && max_reach_sample_ago < first_sample_ago)
+      max_reach_sample_ago = first_sample_ago;
+
+    if (max_sel_reach < sources[i]->reachability)
+      max_sel_reach = sources[i]->reachability;
+
+    if (max_sel_reach_size < sources[i]->reachability_size)
+      max_sel_reach_size = sources[i]->reachability_size;
+  }
+
+  orphan_stratum = REF_GetOrphanStratum();
+  orphan_source = INVALID_SOURCE;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    si = &sources[i]->sel_info;
+
+    /* Reachability is not a requirement for selection.  An unreachable source
+       can still be selected if its newest sample is not older than the oldest
+       sample from reachable sources. */
+    if (!sources[i]->reachability && max_reach_sample_ago < si->last_sample_ago) {
+      mark_source(sources[i], SRC_STALE);
+      continue;
+    }
+
+    /* When the local reference is configured with the orphan option, NTP
+       sources that have stratum equal to the configured local stratum are
+       considered to be orphans (i.e. serving local time while not being
+       synchronised with real time) and are excluded from the normal source
+       selection.  Sources with stratum larger than the local stratum are
+       considered to be directly on indirectly synchronised to an orphan and
+       are always ignored.
+
+       If no selectable source is available and all orphan sources have
+       reference IDs larger than the local ID, no source will be selected and
+       the local reference mode will be activated at some point, i.e. this host
+       will become an orphan.  Otherwise, the orphan source with the smallest
+       reference ID will be selected.  This ensures a group of servers polling
+       each other (with the same orphan configuration) which have no external
+       source can settle down to a state where only one server is serving its
+       local unsychronised time and others are synchronised to it. */
+
+    if (sources[i]->stratum >= orphan_stratum && sources[i]->type == SRC_NTP) {
+      mark_source(sources[i], SRC_ORPHAN);
+
+      if (sources[i]->stratum == orphan_stratum && sources[i]->reachability &&
+          (orphan_source == INVALID_SOURCE ||
+           sources[i]->ref_id < sources[orphan_source]->ref_id))
+        orphan_source = i;
+
+      continue;
+    }
+
+    ++n_sel_sources;
+  }
+
+  /* If no selectable source is available, consider the orphan source */
+  if (!n_sel_sources && orphan_source != INVALID_SOURCE) {
+    uint32_t local_ref_id = NSR_GetLocalRefid(sources[orphan_source]->ip_addr);
+
+    if (!local_ref_id) {
+      LOG(LOGS_ERR, "Unknown local refid in orphan mode");
+    } else if (sources[orphan_source]->ref_id < local_ref_id) {
+      sources[orphan_source]->status = SRC_OK;
+      n_sel_sources = 1;
+      DEBUG_LOG("selecting orphan refid=%"PRIx32, sources[orphan_source]->ref_id);
+    }
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    if (sources[i]->sel_options & SRC_SELECT_TRUST)
+      n_sel_trust_sources++;
+
+    si = &sources[i]->sel_info;
+
+    j1 = n_endpoints;
+    j2 = j1 + 1;
+
+    sort_list[j1].index = i;
+    sort_list[j1].offset = si->lo_limit;
+    sort_list[j1].tag = LOW;
+
+    sort_list[j2].index = i;
+    sort_list[j2].offset = si->hi_limit;
+    sort_list[j2].tag = HIGH;
+
+    n_endpoints += 2;
+  }
+
+  DEBUG_LOG("badstat=%d sel=%d badstat_reach=%o sel_reach=%o size=%d max_reach_ago=%f",
+            n_badstats_sources, n_sel_sources, (unsigned int)max_badstat_reach,
+            (unsigned int)max_sel_reach, max_sel_reach_size, max_reach_sample_ago);
+
+  /* Wait for the next call if we have no source selected and there is
+     a source with bad stats (has less than 3 samples) with reachability
+     equal to shifted maximum reachability of sources with valid stats.
+     This delays selecting source on start with servers using the same
+     polling interval until they all have valid stats. */
+  if (n_badstats_sources && n_sel_sources && selected_source_index == INVALID_SOURCE &&
+      max_sel_reach_size < SOURCE_REACH_BITS && max_sel_reach >> 1 == max_badstat_reach) {
+    mark_ok_sources(SRC_WAITS_STATS);
+    return;
+  }
+
+  if (n_endpoints == 0) {
+    /* No sources provided valid endpoints */
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message("Can't synchronise: no selectable sources", NULL);
+      selected_source_index = INVALID_SOURCE;
+    }
+    return;
+  }
+
+  /* Now sort the endpoint list */
+  qsort((void *) sort_list, n_endpoints, sizeof(struct Sort_Element), compare_sort_elements);
+
+  /* Now search for the interval which is contained in the most
+     individual source intervals.  Any source which overlaps this
+     will be a candidate.
+
+     If we get a case like
+
+     <----------------------->
+         <-->
+                  <-->
+         <===========>
+
+     we will build the interval as shown with '=', whereas with an extra source we get
+
+     <----------------------->
+        <------->
+         <-->
+                  <-->
+         <==>
+
+     The first case is just bad luck - we need extra sources to
+     detect the falseticker, so just make an arbitrary choice based
+     on stratum & stability etc.
+
+     Intervals from sources specified with the trust option have higher
+     priority in the search.
+     */
+
+  trust_depth = best_trust_depth = 0;
+  depth = best_depth = 0;
+  best_lo = best_hi = best_trust_lo = best_trust_hi = 0.0;
+
+  for (i = 0; i < n_endpoints; i++) {
+    switch (sort_list[i].tag) {
+      case LOW:
+        depth++;
+        if (sources[sort_list[i].index]->sel_options & SRC_SELECT_TRUST)
+          trust_depth++;
+        if (trust_depth > best_trust_depth ||
+            (trust_depth == best_trust_depth && depth > best_depth)) {
+          if (trust_depth > best_trust_depth) {
+            best_trust_depth = trust_depth;
+            best_trust_lo = sort_list[i].offset;
+          }
+          best_depth = depth;
+          best_lo = sort_list[i].offset;
+        }
+        break;
+      case HIGH:
+        if (trust_depth == best_trust_depth) {
+          if (depth == best_depth)
+            best_hi = sort_list[i].offset;
+          best_trust_hi = sort_list[i].offset;
+        }
+        if (sources[sort_list[i].index]->sel_options & SRC_SELECT_TRUST)
+          trust_depth--;
+        depth--;
+        break;
+      default:
+        assert(0);
+    }
+    assert(trust_depth <= depth);
+    assert(trust_depth >= 0);
+  }
+
+  assert(depth == 0 && trust_depth == 0);
+  assert(2 * n_sel_sources == n_endpoints);
+
+  if ((best_trust_depth == 0 && best_depth <= n_sel_sources / 2) ||
+      (best_trust_depth > 0 && best_trust_depth <= n_sel_trust_sources / 2)) {
+    /* Could not even get half the reachable (trusted) sources to agree */
+
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message("Can't synchronise: no majority", NULL);
+      REF_SetUnsynchronised();
+      selected_source_index = INVALID_SOURCE;
+    }
+
+    /* .. and mark all sources as falsetickers (so they appear thus
+       on the outputs from the command client) */
+    mark_ok_sources(SRC_FALSETICKER);
+
+    return;
+  }
+
+  /* We have our interval, now work out which source are in it,
+     i.e. build list of admissible sources. */
+
+  n_sel_sources = 0;
+
+  for (i = 0; i < n_sources; i++) {
+    /* This should be the same condition to get into the endpoint
+       list */
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    /* Check if source's interval contains the best interval, or is wholly
+       contained within it.  If there are any trusted sources, other sources
+       are required to be wholly contained within the best interval of the
+       trusted sources to not allow non-trusted sources to move the final
+       offset outside the trusted interval. */
+    if ((sources[i]->sel_info.lo_limit <= best_lo &&
+         sources[i]->sel_info.hi_limit >= best_hi) ||
+        (sources[i]->sel_info.lo_limit >= best_lo &&
+         sources[i]->sel_info.hi_limit <= best_hi)) {
+
+      if (!(best_trust_depth == 0 || (sources[i]->sel_options & SRC_SELECT_TRUST) ||
+            (sources[i]->sel_info.lo_limit >= best_trust_lo &&
+             sources[i]->sel_info.hi_limit <= best_trust_hi))) {
+        mark_source(sources[i], SRC_UNTRUSTED);
+        continue;
+      }
+
+      sel_sources[n_sel_sources++] = i;
+
+      if (sources[i]->sel_options & SRC_SELECT_REQUIRE)
+        sel_req_source = 0;
+    } else {
+      mark_source(sources[i], SRC_FALSETICKER);
+    }
+  }
+
+  if (!n_sel_sources || sel_req_source || n_sel_sources < CNF_GetMinSources()) {
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message("Can't synchronise: %s selectable sources",
+                            !n_sel_sources ? "no" :
+                            sel_req_source ? "no required source in" : "not enough");
+      selected_source_index = INVALID_SOURCE;
+    }
+    mark_ok_sources(SRC_WAITS_SOURCES);
+    return;
+  }
+
+  /* Enable the selectable sources (and trusted if there are any) to
+     vote on leap seconds */
+  for (i = 0; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    if (best_trust_depth && !(sources[index]->sel_options & SRC_SELECT_TRUST))
+      continue;
+    sources[index]->leap_vote = 1;
+  }
+
+  /* If there are any sources with prefer option, reduce the list again
+     only to the preferred sources */
+  for (i = 0; i < n_sel_sources; i++) {
+    if (sources[sel_sources[i]]->sel_options & SRC_SELECT_PREFER)
+      break;
+  }
+  if (i < n_sel_sources) {
+    for (i = j = 0; i < n_sel_sources; i++) {
+      if (!(sources[sel_sources[i]]->sel_options & SRC_SELECT_PREFER))
+        mark_source(sources[sel_sources[i]], SRC_NONPREFERRED);
+      else
+        sel_sources[j++] = sel_sources[i];
+    }
+    assert(j > 0);
+    n_sel_sources = j;
+    sel_prefer = 1;
+  } else {
+    sel_prefer = 0;
+  }
+
+  /* Find minimum stratum */
+
+  index = sel_sources[0];
+  min_stratum = sources[index]->stratum;
+  for (i = 1; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    stratum = sources[index]->stratum;
+    if (stratum < min_stratum)
+      min_stratum = stratum;
+  }
+
+  /* Update scores and find the source with maximum score */
+
+  max_score_index = INVALID_SOURCE;
+  max_score = 0.0;
+  sel_src_distance = 0.0;
+
+  if (selected_source_index != INVALID_SOURCE)
+    sel_src_distance = sources[selected_source_index]->sel_info.root_distance +
+      (sources[selected_source_index]->stratum - min_stratum) * stratum_weight;
+
+  for (i = 0; i < n_sources; i++) {
+    /* Reset score for non-selectable sources */
+    if (sources[i]->status != SRC_OK ||
+        (sel_prefer && !(sources[i]->sel_options & SRC_SELECT_PREFER))) {
+      sources[i]->sel_score = 1.0;
+      sources[i]->distant = DISTANT_PENALTY;
+      continue;
+    }
+
+    distance = sources[i]->sel_info.root_distance +
+      (sources[i]->stratum - min_stratum) * stratum_weight;
+    if (sources[i]->type == SRC_NTP)
+      distance += reselect_distance;
+
+    if (selected_source_index != INVALID_SOURCE) {
+      /* Update score, but only for source pairs where one source
+         has a new sample */
+      if (sources[i] == updated_inst ||
+          sources[selected_source_index] == updated_inst) {
+
+        sources[i]->sel_score *= sel_src_distance / distance;
+
+        if (sources[i]->sel_score < 1.0)
+          sources[i]->sel_score = 1.0;
+      }
+    } else {
+      /* When there is no selected source yet, assign scores so that the
+         source with minimum distance will have maximum score.  The scores
+         will be reset when the source is selected later in this function. */
+      sources[i]->sel_score = 1.0 / distance;
+    }
+
+    DEBUG_LOG("%s score=%f dist=%f",
+              source_to_string(sources[i]), sources[i]->sel_score, distance);
+
+    if (max_score < sources[i]->sel_score) {
+      max_score = sources[i]->sel_score;
+      max_score_index = i;
+    }
+  }
+
+  assert(max_score_index != INVALID_SOURCE);
+
+  /* Is the current source still a survivor and no other source has reached
+     the score limit? */
+  if (selected_source_index == INVALID_SOURCE ||
+      sources[selected_source_index]->status != SRC_OK ||
+      (max_score_index != selected_source_index && max_score > SCORE_LIMIT)) {
+
+    /* Before selecting the new synchronisation source wait until the reference
+       can be updated */
+    if (sources[max_score_index]->updates == 0) {
+      selected_source_index = INVALID_SOURCE;
+      mark_ok_sources(SRC_WAITS_UPDATE);
+      return;
+    }
+
+    selected_source_index = max_score_index;
+    log_selection_source("Selected source %s", sources[selected_source_index]);
+
+    /* New source has been selected, reset all scores */
+    for (i = 0; i < n_sources; i++) {
+      sources[i]->sel_score = 1.0;
+      sources[i]->distant = 0;
+    }
+  }
+
+  mark_source(sources[selected_source_index], SRC_SELECTED);
+
+  /* Don't update reference when the selected source has no new samples */
+
+  if (sources[selected_source_index]->updates == 0) {
+    /* Mark the remaining sources as last combine_sources() call */
+
+    for (i = 0; i < n_sel_sources; i++) {
+      index = sel_sources[i];
+      if (sources[index]->status == SRC_OK)
+        mark_source(sources[index], sources[index]->distant ? SRC_DISTANT : SRC_UNSELECTED);
+    }
+    return;
+  }
+
+  for (i = 0; i < n_sources; i++)
+    sources[i]->updates = 0;
+
+  leap_status = get_leap_status();
+
+  /* Now just use the statistics of the selected source combined with
+     the other selectable sources for trimming the local clock */
+
+  SST_GetTrackingData(sources[selected_source_index]->stats, &ref_time,
+                      &src_offset, &src_offset_sd,
+                      &src_frequency, &src_frequency_sd, &src_skew,
+                      &src_root_delay, &src_root_dispersion);
+
+  combined = combine_sources(n_sel_sources, &ref_time, &src_offset, &src_offset_sd,
+                             &src_frequency, &src_frequency_sd, &src_skew);
+
+  REF_SetReference(sources[selected_source_index]->stratum,
+                   leap_status, combined,
+                   sources[selected_source_index]->ref_id,
+                   sources[selected_source_index]->ip_addr,
+                   &ref_time, src_offset, src_offset_sd,
+                   src_frequency, src_frequency_sd, src_skew,
+                   src_root_delay, src_root_dispersion);
+}
+
+/* ================================================== */
+/* Force reselecting the best source */
+
+void
+SRC_ReselectSource(void)
+{
+  selected_source_index = INVALID_SOURCE;
+  SRC_SelectSource(NULL);
+}
+
+/* ================================================== */
+
+void
+SRC_SetReselectDistance(double distance)
+{
+  if (reselect_distance != distance) {
+    reselect_distance = distance;
+    LOG(LOGS_INFO, "New reselect distance %f", distance);
+  }
+}
+
+/* ================================================== */
+/* This routine is registered as a callback with the local clock
+   module, to be called whenever the local clock changes frequency or
+   is slewed.  It runs through all the existing source statistics, and
+   adjusts them to make them look as though they were sampled under
+   the new regime. */
+
+static void
+slew_sources(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything)
+{
+  int i;
+
+  for (i=0; i<n_sources; i++) {
+    if (change_type == LCL_ChangeUnknownStep) {
+      SST_ResetInstance(sources[i]->stats);
+    } else {
+      SST_SlewSamples(sources[i]->stats, cooked, dfreq, doffset);
+    }
+  }
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    /* Update selection status */
+    SRC_SelectSource(NULL);
+  }
+}
+
+/* ================================================== */
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    SST_AddDispersion(sources[i]->stats, dispersion);
+  }
+}
+
+/* ================================================== */
+
+static int
+get_dumpfile(SRC_Instance inst, char *filename, size_t len)
+{
+  /* Use the IP address, or reference ID with reference clocks */
+  switch (inst->type) {
+    case SRC_NTP:
+      if (!UTI_IsIPReal(inst->ip_addr) ||
+          snprintf(filename, len, "%s", source_to_string(inst)) >= len)
+        return 0;
+      break;
+    case SRC_REFCLOCK:
+      if (snprintf(filename, len, "refid:%08"PRIx32, inst->ref_id) >= len)
+        return 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+save_source(SRC_Instance inst)
+{
+  char filename[64], *dumpdir, *ntp_name;
+  FILE *f;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir)
+    return;
+
+  if (!get_dumpfile(inst, filename, sizeof (filename)))
+    return;
+
+  f = UTI_OpenFile(dumpdir, filename, ".dat", 'w', 0644);
+  if (!f)
+    return;
+
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : ".";
+
+  if (fprintf(f, "%s%s\n%d %o %d %d %d\n",
+              DUMP_IDENTIFIER, ntp_name, inst->authenticated,
+              (unsigned int)inst->reachability, inst->reachability_size,
+              inst->stratum, (int)inst->leap) < 0 ||
+      !SST_SaveToFile(inst->stats, f)) {
+    fclose(f);
+    if (!UTI_RemoveFile(dumpdir, filename, ".dat"))
+      ;
+    return;
+  }
+
+  fclose(f);
+}
+
+/* ================================================== */
+/* This is called to dump out the source measurement registers */
+
+void
+SRC_DumpSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++)
+    save_source(sources[i]);
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 1
+
+static void
+load_source(SRC_Instance inst)
+{
+  char filename[64], line[256], *dumpdir, *ntp_name, *words[MAX_WORDS];
+  int auth, leap, reach_size, stratum;
+  unsigned int reach;
+  FILE *f;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir)
+    return;
+
+  if (!get_dumpfile(inst, filename, sizeof (filename)))
+    return;
+
+  f = UTI_OpenFile(dumpdir, filename, ".dat", 'r', 0);
+  if (!f)
+    return;
+
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : NULL;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        (inst->type == SRC_NTP && (!ntp_name || strcmp(words[0], ntp_name) != 0)) ||
+      !fgets(line, sizeof (line), f) ||
+        sscanf(words[0], "%d %o %d %d %d",
+               &auth, &reach, &reach_size, &stratum, &leap) != 5 ||
+        (!auth && inst->authenticated) ||
+        stratum < 0 || stratum >= NTP_MAX_STRATUM ||
+        leap < LEAP_Normal || leap >= LEAP_Unsynchronised ||
+      !SST_LoadFromFile(inst->stats, f)) {
+    LOG(LOGS_WARN, "Could not load dump file for %s", source_to_string(inst));
+    fclose(f);
+    return;
+  }
+
+  inst->reachability = reach & ((1U << SOURCE_REACH_BITS) - 1);
+  inst->reachability_size = CLAMP(0, reach_size, SOURCE_REACH_BITS);
+  inst->stratum = stratum;
+  inst->leap = leap;
+
+  LOG(LOGS_INFO, "Loaded dump file for %s", source_to_string(inst));
+
+  fclose(f);
+}
+
+/* ================================================== */
+
+void
+SRC_ReloadSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    load_source(sources[i]);
+
+    /* Allow an immediate update of the reference */
+    sources[i]->updates++;
+  }
+
+  /* Select sources and set the reference */
+  SRC_SelectSource(NULL);
+}
+
+/* ================================================== */
+
+void
+SRC_RemoveDumpFiles(void)
+{
+  char pattern[PATH_MAX], name[64], *dumpdir, *s;
+  IPAddr ip_addr;
+  glob_t gl;
+  size_t i;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir ||
+      snprintf(pattern, sizeof (pattern), "%s/*.dat", dumpdir) >= sizeof (pattern))
+    return;
+
+  if (glob(pattern, 0, NULL, &gl))
+    return;
+
+  for (i = 0; i < gl.gl_pathc; i++) {
+    s = strrchr(gl.gl_pathv[i], '/');
+    if (!s || snprintf(name, sizeof (name), "%s", s + 1) >= sizeof (name))
+      continue;
+
+    /* Remove .dat extension */
+    if (strlen(name) < 4)
+      continue;
+    name[strlen(name) - 4] = '\0';
+
+    /* Check if it looks like name of an actual dump file */
+    if (strncmp(name, "refid:", 6) && !UTI_StringToIP(name, &ip_addr))
+      continue;
+
+    if (!UTI_RemoveFile(NULL, gl.gl_pathv[i], NULL))
+      ;
+  }
+
+  globfree(&gl);
+}
+
+/* ================================================== */
+
+void
+SRC_ResetSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++)
+    SRC_ResetInstance(sources[i]);
+}
+
+/* ================================================== */
+
+int
+SRC_IsSyncPeer(SRC_Instance inst)
+{
+  if (inst->index == selected_source_index) {
+    return 1;
+  } else {
+    return 0;
+  }
+
+}
+
+/* ================================================== */
+
+int
+SRC_IsReachable(SRC_Instance inst)
+{
+  return inst->reachability != 0;
+}
+
+/* ================================================== */
+
+int
+SRC_ReadNumberOfSources(void)
+{
+  return n_sources;
+}
+
+/* ================================================== */
+
+int
+SRC_ActiveSources(void)
+{
+  int i, r;
+
+  for (i = r = 0; i < n_sources; i++)
+    if (sources[i]->active)
+      r++;
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+SRC_ReportSource(int index, RPT_SourceReport *report, struct timespec *now)
+{
+  SRC_Instance src;
+  if ((index >= n_sources) || (index < 0)) {
+    return 0;
+  } else {
+    src = sources[index];
+
+    if (src->ip_addr)
+      report->ip_addr = *src->ip_addr;
+    else {
+      /* Use refid as an address */
+      report->ip_addr.addr.in4 = src->ref_id;
+      report->ip_addr.family = IPADDR_INET4;
+    }
+
+    report->stratum = src->stratum;
+
+    switch (src->status) {
+      case SRC_FALSETICKER:
+        report->state = RPT_FALSETICKER;
+        break;
+      case SRC_JITTERY:
+        report->state = RPT_JITTERY;
+        break;
+      case SRC_WAITS_SOURCES:
+      case SRC_NONPREFERRED:
+      case SRC_WAITS_UPDATE:
+      case SRC_DISTANT:
+      case SRC_OUTLIER:
+        report->state = RPT_SELECTABLE;
+        break;
+      case SRC_UNSELECTED:
+        report->state = RPT_UNSELECTED;
+        break;
+      case SRC_SELECTED:
+        report->state = RPT_SELECTED;
+        break;
+      default:
+        report->state = RPT_NONSELECTABLE;
+        break;
+    }
+
+    report->reachability = src->reachability;
+
+    /* Call stats module to fill out estimates */
+    SST_DoSourceReport(src->stats, report, now);
+
+    return 1;
+  }
+
+}
+
+/* ================================================== */
+
+int
+SRC_ReportSourcestats(int index, RPT_SourcestatsReport *report, struct timespec *now)
+{ 
+  SRC_Instance src;
+
+  if ((index >= n_sources) || (index < 0)) {
+    return 0;
+  } else {
+    src = sources[index];
+    report->ref_id = src->ref_id;
+    if (src->ip_addr)
+      report->ip_addr = *src->ip_addr;
+    else
+      report->ip_addr.family = IPADDR_UNSPEC; 
+    SST_DoSourcestatsReport(src->stats, report, now);
+    return 1;
+  }
+}
+
+/* ================================================== */
+
+static char
+get_status_char(SRC_Status status)
+{
+  switch (status) {
+    case SRC_UNSELECTABLE:
+      return 'N';
+    case SRC_UNSYNCHRONISED:
+      return 's';
+    case SRC_BAD_STATS:
+      return 'M';
+    case SRC_BAD_DISTANCE:
+      return 'd';
+    case SRC_JITTERY:
+      return '~';
+    case SRC_WAITS_STATS:
+      return 'w';
+    case SRC_STALE:
+      return 'S';
+    case SRC_ORPHAN:
+      return 'O';
+    case SRC_UNTRUSTED:
+      return 'T';
+    case SRC_FALSETICKER:
+      return 'x';
+    case SRC_WAITS_SOURCES:
+      return 'W';
+    case SRC_NONPREFERRED:
+      return 'P';
+    case SRC_WAITS_UPDATE:
+      return 'U';
+    case SRC_DISTANT:
+      return 'D';
+    case SRC_OUTLIER:
+      return 'L';
+    case SRC_UNSELECTED:
+      return '+';
+    case SRC_SELECTED:
+      return '*';
+    default:
+      return '?';
+  }
+}
+
+/* ================================================== */
+
+int
+SRC_GetSelectReport(int index, RPT_SelectReport *report)
+{
+  SRC_Instance inst;
+
+  if (index >= n_sources || index < 0)
+    return 0;
+
+  inst = sources[index];
+
+  report->ref_id = inst->ref_id;
+  if (inst->ip_addr)
+    report->ip_addr = *inst->ip_addr;
+  else
+    report->ip_addr.family = IPADDR_UNSPEC;
+  report->state_char = get_status_char(inst->status);
+  report->authentication = inst->authenticated;
+  report->leap = inst->leap;
+  report->conf_options = inst->conf_sel_options;
+  report->eff_options = inst->sel_options;
+  report->last_sample_ago = inst->sel_info.last_sample_ago;
+  report->score = inst->sel_score;
+  report->lo_limit = inst->sel_info.lo_limit;
+  report->hi_limit = inst->sel_info.hi_limit;
+
+  return 1;
+}
+
+/* ================================================== */
+
+SRC_Type
+SRC_GetType(int index)
+{
+  if ((index >= n_sources) || (index < 0))
+    return -1;
+  return sources[index]->type;
+}
+
+/* ================================================== */
diff --git a/sources.h b/sources.h
new file mode 100644
index 0000000..6c799bb
--- /dev/null
+++ b/sources.h
@@ -0,0 +1,140 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header for the module that manages the collection of all
+  sources that we are making measurements from.  This include all NTP
+  servers & peers, locally connected reference sources, eye/wristwatch
+  drivers etc */
+
+#ifndef GOT_SOURCES_H
+#define GOT_SOURCES_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+#include "reports.h"
+#include "sourcestats.h"
+
+/* Size of the source reachability register */
+#define SOURCE_REACH_BITS 8
+
+/* This datatype is used to hold information about sources.  The
+   instance must be passed when calling many of the interface
+   functions */
+
+typedef struct SRC_Instance_Record *SRC_Instance;
+
+/* Initialisation function */
+extern void SRC_Initialise(void);
+
+/* Finalisation function */
+extern void SRC_Finalise(void);
+
+/* Modes for selecting NTP sources based on their authentication status */
+typedef enum {
+  SRC_AUTHSELECT_IGNORE,
+  SRC_AUTHSELECT_MIX,
+  SRC_AUTHSELECT_PREFER,
+  SRC_AUTHSELECT_REQUIRE,
+} SRC_AuthSelectMode;
+
+typedef enum {
+  SRC_NTP,                      /* NTP client/peer */
+  SRC_REFCLOCK                  /* Rerefence clock */
+} SRC_Type;
+
+/* Function to create a new instance.  This would be called by one of
+   the individual source-type instance creation routines. */
+
+extern SRC_Instance SRC_CreateNewInstance(uint32_t ref_id, SRC_Type type, int authenticated,
+                                          int sel_options, IPAddr *addr, int min_samples,
+                                          int max_samples, double min_delay, double asymmetry);
+
+/* Function to get rid of a source when it is being unconfigured.
+   This may cause the current reference source to be reselected, if this
+   was the reference source or contributed significantly to a
+   falseticker decision. */
+
+extern void SRC_DestroyInstance(SRC_Instance instance);
+
+/* Function to reset a source */
+extern void SRC_ResetInstance(SRC_Instance instance);
+
+/* Function to change the sources's reference ID and IP address */
+extern void SRC_SetRefid(SRC_Instance instance, uint32_t ref_id, IPAddr *addr);
+
+/* Function to get access to the sourcestats instance */
+extern SST_Stats SRC_GetSourcestats(SRC_Instance instance);
+
+/* Function to update the stratum and leap status of the source */
+extern void SRC_UpdateStatus(SRC_Instance instance, int stratum, NTP_Leap leap);
+
+/* Function to accumulate a new sample from the source */
+extern void SRC_AccumulateSample(SRC_Instance instance, NTP_Sample *sample);
+
+/* This routine sets the source as receiving reachability updates */
+extern void SRC_SetActive(SRC_Instance inst);
+
+/* This routine sets the source as not receiving reachability updates */
+extern void SRC_UnsetActive(SRC_Instance inst);
+
+/* This routine updates the reachability register */
+extern void SRC_UpdateReachability(SRC_Instance inst, int reachable);
+
+/* This routine marks the source unreachable */
+extern void SRC_ResetReachability(SRC_Instance inst);
+
+/* This routine is used to select the best source from amongst those
+   we currently have valid data on, and use it as the tracking base
+   for the local time.  Updates are made to the local reference only
+   when the selected source was updated (set as updated_inst) since
+   the last reference update.  This avoids updating the frequency
+   tracking for every sample from other sources - only the ones from
+   the selected reference make a difference. */
+extern void SRC_SelectSource(SRC_Instance updated_inst);
+
+/* Force reselecting the best source */
+extern void SRC_ReselectSource(void);
+
+/* Set reselect distance */
+extern void SRC_SetReselectDistance(double distance);
+
+extern void SRC_DumpSources(void);
+extern void SRC_ReloadSources(void);
+extern void SRC_RemoveDumpFiles(void);
+
+extern void SRC_ResetSources(void);
+
+extern int SRC_IsSyncPeer(SRC_Instance inst);
+extern int SRC_IsReachable(SRC_Instance inst);
+extern int SRC_ReadNumberOfSources(void);
+extern int SRC_ActiveSources(void);
+
+extern int SRC_ReportSource(int index, RPT_SourceReport *report, struct timespec *now);
+extern int SRC_ReportSourcestats(int index, RPT_SourcestatsReport *report, struct timespec *now);
+extern int SRC_GetSelectReport(int index, RPT_SelectReport *report);
+
+extern SRC_Type SRC_GetType(int index);
+
+#endif /* GOT_SOURCES_H */
diff --git a/sourcestats.c b/sourcestats.c
new file mode 100644
index 0000000..eb4705e
--- /dev/null
+++ b/sourcestats.c
@@ -0,0 +1,1040 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2014, 2016-2018, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains the routines that do the statistical
+  analysis on the samples obtained from the sources,
+  to determined frequencies and error bounds. */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sourcestats.h"
+#include "memory.h"
+#include "regress.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "local.h"
+
+/* ================================================== */
+/* Define the maxumum number of samples that we want
+   to store per source */
+#define MAX_SAMPLES 64
+
+/* This is the assumed worst case bound on an unknown frequency,
+   2000ppm, which would be pretty bad */
+#define WORST_CASE_FREQ_BOUND (2000.0/1.0e6)
+
+/* The minimum and maximum assumed skew */
+#define MIN_SKEW 1.0e-12
+#define MAX_SKEW 1.0e+02
+
+/* The minimum standard deviation */
+#define MIN_STDDEV 1.0e-9
+
+/* The worst case bound on an unknown standard deviation of the offset */
+#define WORST_CASE_STDDEV_BOUND 4.0
+
+/* The asymmetry of network jitter when all jitter is in one direction */
+#define MAX_ASYMMETRY 0.5
+
+/* The minimum estimated asymmetry that can activate the offset correction */
+#define MIN_ASYMMETRY 0.45
+
+/* The minimum number of consecutive asymmetries with the same sign needed
+   to activate the offset correction */
+#define MIN_ASYMMETRY_RUN 10
+
+/* The maximum value of the counter */
+#define MAX_ASYMMETRY_RUN 1000
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+/* This data structure is used to hold the history of data from the
+   source */
+
+struct SST_Stats_Record {
+
+  /* Reference ID and IP address of source, used for logging to statistics log */
+  uint32_t refid;
+  IPAddr *ip_addr;
+
+  /* User defined minimum and maximum number of samples */
+  int min_samples;
+  int max_samples;
+
+  /* User defined minimum delay */
+  double fixed_min_delay;
+
+  /* User defined asymmetry of network jitter */
+  double fixed_asymmetry;
+
+  /* Number of samples currently stored.  The samples are stored in circular
+     buffer. */
+  int n_samples;
+
+  /* Number of extra samples stored in sample_times, offsets and peer_delays
+     arrays that are used to extend the runs test */
+  int runs_samples;
+
+  /* The index of the newest sample */
+  int last_sample;
+
+  /* Flag indicating whether last regression was successful */
+  int regression_ok;
+
+  /* The best individual sample that we are holding, in terms of the minimum
+     root distance at the present time */
+  int best_single_sample;
+
+  /* The index of the sample with minimum delay in peer_delays */
+  int min_delay_sample;
+
+  /* This is the estimated offset (+ve => local fast) at a particular time */
+  double estimated_offset;
+  double estimated_offset_sd;
+  struct timespec offset_time;
+
+  /* Number of runs of the same sign amongst the residuals */
+  int nruns;
+
+  /* Number of consecutive estimated asymmetries with the same sign.
+     The sign of the number encodes the sign of the asymmetry. */
+  int asymmetry_run;
+
+  /* This is the latest estimated asymmetry of network jitter */
+  double asymmetry;
+
+  /* This value contains the estimated frequency.  This is the number
+     of seconds that the local clock gains relative to the reference
+     source per unit local time.  (Positive => local clock fast,
+     negative => local clock slow) */
+  double estimated_frequency;
+  double estimated_frequency_sd;
+
+  /* This is the assumed worst case bounds on the estimated frequency.
+     We assume that the true frequency lies within +/- half this much
+     about estimated_frequency */
+  double skew;
+
+  /* This is the estimated standard deviation of the data points */
+  double std_dev;
+
+  /* This array contains the sample epochs, in terms of the local
+     clock. */
+  struct timespec sample_times[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of offsets, in seconds, corresponding to the
+     sample times.  In this module, we use the convention that
+     positive means the local clock is FAST of the source and negative
+     means it is SLOW.  This is contrary to the convention in the NTP
+     stuff. */
+  double offsets[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of the offsets as originally measured.  Local
+     clock fast of real time is indicated by positive values.  This
+     array is not slewed to adjust the readings when we apply
+     adjustments to the local clock, as is done for the array
+     'offset'. */
+  double orig_offsets[MAX_SAMPLES];
+
+  /* This is an array of peer delays, in seconds, being the roundtrip
+     measurement delay to the peer */
+  double peer_delays[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of peer dispersions, being the skew and local
+     precision dispersion terms from sampling the peer */
+  double peer_dispersions[MAX_SAMPLES];
+
+  /* This array contains the root delays of each sample, in seconds */
+  double root_delays[MAX_SAMPLES];
+
+  /* This array contains the root dispersions of each sample at the
+     time of the measurements */
+  double root_dispersions[MAX_SAMPLES];
+};
+
+/* ================================================== */
+
+static void find_min_delay_sample(SST_Stats inst);
+static int get_buf_index(SST_Stats inst, int i);
+
+/* ================================================== */
+
+void
+SST_Initialise(void)
+{
+  logfileid = CNF_GetLogStatistics() ? LOG_FileOpen("statistics",
+      "   Date (UTC) Time     IP Address    Std dev'n Est offset  Offset sd  Diff freq   Est skew  Stress  Ns  Bs  Nr  Asym")
+    : -1;
+}
+
+/* ================================================== */
+
+void
+SST_Finalise(void)
+{
+}
+
+/* ================================================== */
+/* This function creates a new instance of the statistics handler */
+
+SST_Stats
+SST_CreateInstance(uint32_t refid, IPAddr *addr, int min_samples, int max_samples,
+                   double min_delay, double asymmetry)
+{
+  SST_Stats inst;
+  inst = MallocNew(struct SST_Stats_Record);
+
+  inst->max_samples = max_samples > 0 ? CLAMP(1, max_samples, MAX_SAMPLES) : MAX_SAMPLES;
+  inst->min_samples = CLAMP(1, min_samples, inst->max_samples);
+  inst->fixed_min_delay = min_delay;
+  inst->fixed_asymmetry = asymmetry;
+
+  SST_SetRefid(inst, refid, addr);
+  SST_ResetInstance(inst);
+
+  return inst;
+}
+
+/* ================================================== */
+/* This function deletes an instance of the statistics handler. */
+
+void
+SST_DeleteInstance(SST_Stats inst)
+{
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+SST_ResetInstance(SST_Stats inst)
+{
+  inst->n_samples = 0;
+  inst->runs_samples = 0;
+  inst->last_sample = 0;
+  inst->regression_ok = 0;
+  inst->best_single_sample = 0;
+  inst->min_delay_sample = 0;
+  inst->estimated_frequency = 0;
+  inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
+  inst->skew = WORST_CASE_FREQ_BOUND;
+  inst->estimated_offset = 0.0;
+  inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
+  UTI_ZeroTimespec(&inst->offset_time);
+  inst->std_dev = WORST_CASE_STDDEV_BOUND;
+  inst->nruns = 0;
+  inst->asymmetry_run = 0;
+  inst->asymmetry = 0.0;
+}
+
+/* ================================================== */
+
+void
+SST_SetRefid(SST_Stats inst, uint32_t refid, IPAddr *addr)
+{
+  inst->refid = refid;
+  inst->ip_addr = addr;
+}
+
+/* ================================================== */
+/* This function is called to prune the register down when it is full.
+   For now, just discard the oldest sample.  */
+
+static void
+prune_register(SST_Stats inst, int new_oldest)
+{
+  if (!new_oldest)
+    return;
+
+  assert(inst->n_samples >= new_oldest);
+  inst->n_samples -= new_oldest;
+  inst->runs_samples += new_oldest;
+  if (inst->runs_samples > inst->n_samples * (REGRESS_RUNS_RATIO - 1))
+    inst->runs_samples = inst->n_samples * (REGRESS_RUNS_RATIO - 1);
+  
+  assert(inst->n_samples + inst->runs_samples <= MAX_SAMPLES * REGRESS_RUNS_RATIO);
+
+  find_min_delay_sample(inst);
+}
+
+/* ================================================== */
+
+void
+SST_AccumulateSample(SST_Stats inst, NTP_Sample *sample)
+{
+  int n, m;
+
+  /* Make room for the new sample */
+  if (inst->n_samples > 0 &&
+      (inst->n_samples == MAX_SAMPLES || inst->n_samples == inst->max_samples)) {
+    prune_register(inst, 1);
+  }
+
+  /* Make sure it's newer than the last sample */
+  if (inst->n_samples &&
+      UTI_CompareTimespecs(&inst->sample_times[inst->last_sample], &sample->time) >= 0) {
+    LOG(LOGS_WARN, "Out of order sample detected, discarding history for %s",
+        inst->ip_addr ? UTI_IPToString(inst->ip_addr) : UTI_RefidToString(inst->refid));
+    SST_ResetInstance(inst);
+  }
+
+  n = inst->last_sample = (inst->last_sample + 1) %
+    (MAX_SAMPLES * REGRESS_RUNS_RATIO);
+  m = n % MAX_SAMPLES;
+
+  /* WE HAVE TO NEGATE OFFSET IN THIS CALL, IT IS HERE THAT THE SENSE OF OFFSET
+     IS FLIPPED */
+  inst->sample_times[n] = sample->time;
+  inst->offsets[n] = -sample->offset;
+  inst->orig_offsets[m] = -sample->offset;
+  inst->peer_delays[n] = sample->peer_delay;
+  inst->peer_dispersions[m] = sample->peer_dispersion;
+  inst->root_delays[m] = sample->root_delay;
+  inst->root_dispersions[m] = sample->root_dispersion;
+ 
+  if (inst->peer_delays[n] < inst->fixed_min_delay)
+    inst->peer_delays[n] = 2.0 * inst->fixed_min_delay - inst->peer_delays[n];
+
+  if (!inst->n_samples || inst->peer_delays[n] < inst->peer_delays[inst->min_delay_sample])
+    inst->min_delay_sample = n;
+
+  ++inst->n_samples;
+}
+
+/* ================================================== */
+/* Return index of the i-th sample in the sample_times and offset buffers,
+   i can be negative down to -runs_samples */
+
+static int
+get_runsbuf_index(SST_Stats inst, int i)
+{
+  return (unsigned int)(inst->last_sample + 2 * MAX_SAMPLES * REGRESS_RUNS_RATIO -
+      inst->n_samples + i + 1) % (MAX_SAMPLES * REGRESS_RUNS_RATIO);
+}
+
+/* ================================================== */
+/* Return index of the i-th sample in the other buffers */
+
+static int
+get_buf_index(SST_Stats inst, int i)
+{
+  return (unsigned int)(inst->last_sample + MAX_SAMPLES * REGRESS_RUNS_RATIO -
+      inst->n_samples + i + 1) % MAX_SAMPLES;
+}
+
+/* ================================================== */
+/* This function is used by both the regression routines to find the
+   time interval between each historical sample and the most recent
+   one */
+
+static void
+convert_to_intervals(SST_Stats inst, double *times_back)
+{
+  struct timespec *ts;
+  int i;
+
+  ts = &inst->sample_times[inst->last_sample];
+  for (i = -inst->runs_samples; i < inst->n_samples; i++) {
+    /* The entries in times_back[] should end up negative */
+    times_back[i] = UTI_DiffTimespecsToDouble(&inst->sample_times[get_runsbuf_index(inst, i)], ts);
+  }
+}
+
+/* ================================================== */
+
+static void
+find_best_sample_index(SST_Stats inst, double *times_back)
+{
+  /* With the value of skew that has been computed, see which of the
+     samples offers the tightest bound on root distance */
+
+  double root_distance, best_root_distance;
+  double elapsed;
+  int i, j, best_index;
+
+  if (!inst->n_samples)
+    return;
+
+  best_index = -1;
+  best_root_distance = DBL_MAX;
+
+  for (i = 0; i < inst->n_samples; i++) {
+    j = get_buf_index(inst, i);
+
+    elapsed = -times_back[i];
+    assert(elapsed >= 0.0);
+
+    root_distance = inst->root_dispersions[j] + elapsed * inst->skew + 0.5 * inst->root_delays[j];
+    if (root_distance < best_root_distance) {
+      best_root_distance = root_distance;
+      best_index = i;
+    }
+  }
+
+  assert(best_index >= 0);
+  inst->best_single_sample = best_index;
+}
+
+/* ================================================== */
+
+static void
+find_min_delay_sample(SST_Stats inst)
+{
+  int i, index;
+
+  inst->min_delay_sample = get_runsbuf_index(inst, -inst->runs_samples);
+
+  for (i = -inst->runs_samples + 1; i < inst->n_samples; i++) {
+    index = get_runsbuf_index(inst, i);
+    if (inst->peer_delays[index] < inst->peer_delays[inst->min_delay_sample])
+      inst->min_delay_sample = index;
+  }
+}
+
+/* ================================================== */
+/* This function estimates asymmetry of network jitter on the path to the
+   source as a slope of offset against network delay in multiple linear
+   regression.  If the asymmetry is significant and its sign doesn't change
+   frequently, the measured offsets (which are used later to estimate the
+   offset and frequency of the clock) are corrected to correspond to the
+   minimum network delay.  This can significantly improve the accuracy and
+   stability of the estimated offset and frequency. */
+
+static int
+estimate_asymmetry(double *times_back, double *offsets, double *delays, int n,
+                   double *asymmetry, int *asymmetry_run)
+{
+  double a;
+
+  /* Reset the counter when the regression fails or the sign changes */
+  if (!RGR_MultipleRegress(times_back, delays, offsets, n, &a) ||
+      a * *asymmetry_run < 0.0) {
+    *asymmetry = 0;
+    *asymmetry_run = 0.0;
+    return 0;
+  }
+
+  if (a <= -MIN_ASYMMETRY && *asymmetry_run > -MAX_ASYMMETRY_RUN)
+    (*asymmetry_run)--;
+  else if (a >= MIN_ASYMMETRY && *asymmetry_run < MAX_ASYMMETRY_RUN)
+    (*asymmetry_run)++;
+
+  if (abs(*asymmetry_run) < MIN_ASYMMETRY_RUN)
+    return 0;
+
+  *asymmetry = CLAMP(-MAX_ASYMMETRY, a, MAX_ASYMMETRY);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+correct_asymmetry(SST_Stats inst, double *times_back, double *offsets)
+{
+  double min_delay, delays[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  int i, n;
+
+  /* Check if the asymmetry was not specified to be zero */
+  if (inst->fixed_asymmetry == 0.0)
+    return;
+
+  min_delay = SST_MinRoundTripDelay(inst);
+  n = inst->runs_samples + inst->n_samples;
+
+  for (i = 0; i < n; i++)
+    delays[i] = inst->peer_delays[get_runsbuf_index(inst, i - inst->runs_samples)] -
+                min_delay;
+
+  if (fabs(inst->fixed_asymmetry) <= MAX_ASYMMETRY) {
+    inst->asymmetry = inst->fixed_asymmetry;
+  } else {
+    if (!estimate_asymmetry(times_back, offsets, delays, n,
+                            &inst->asymmetry, &inst->asymmetry_run))
+      return;
+  }
+
+  /* Correct the offsets */
+  for (i = 0; i < n; i++)
+    offsets[i] -= inst->asymmetry * delays[i];
+}
+
+/* ================================================== */
+
+/* This defines the assumed ratio between the standard deviation of
+   the samples and the peer distance as measured from the round trip
+   time.  E.g. a value of 4 means that we think the standard deviation
+   is four times the fluctuation  of the peer distance */
+
+#define SD_TO_DIST_RATIO 0.7
+
+/* ================================================== */
+/* This function runs the linear regression operation on the data.  It
+   finds the set of most recent samples that give the tightest
+   confidence interval for the frequency, and truncates the register
+   down to that number of samples */
+
+void
+SST_DoNewRegression(SST_Stats inst)
+{
+  double times_back[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  double offsets[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  double peer_distances[MAX_SAMPLES];
+  double weights[MAX_SAMPLES];
+
+  int degrees_of_freedom;
+  int best_start, times_back_start;
+  double est_intercept, est_slope, est_var, est_intercept_sd, est_slope_sd;
+  int i, j, nruns;
+  double min_distance, median_distance;
+  double sd_weight, sd;
+  double old_skew, old_freq, stress;
+  double precision;
+
+  convert_to_intervals(inst, times_back + inst->runs_samples);
+
+  if (inst->n_samples > 0) {
+    for (i = -inst->runs_samples; i < inst->n_samples; i++) {
+      offsets[i + inst->runs_samples] = inst->offsets[get_runsbuf_index(inst, i)];
+    }
+  
+    for (i = 0, min_distance = DBL_MAX; i < inst->n_samples; i++) {
+      j = get_buf_index(inst, i);
+      peer_distances[i] = 0.5 * inst->peer_delays[get_runsbuf_index(inst, i)] +
+                          inst->peer_dispersions[j];
+      if (peer_distances[i] < min_distance) {
+        min_distance = peer_distances[i];
+      }
+    }
+
+    /* And now, work out the weight vector */
+
+    precision = LCL_GetSysPrecisionAsQuantum();
+    median_distance = RGR_FindMedian(peer_distances, inst->n_samples);
+
+    sd = (median_distance - min_distance) / SD_TO_DIST_RATIO;
+    sd = CLAMP(precision, sd, min_distance);
+    min_distance += precision;
+
+    for (i=0; i<inst->n_samples; i++) {
+      sd_weight = 1.0;
+      if (peer_distances[i] > min_distance)
+        sd_weight += (peer_distances[i] - min_distance) / sd;
+      weights[i] = SQUARE(sd_weight);
+    }
+  }
+
+  correct_asymmetry(inst, times_back, offsets);
+
+  inst->regression_ok = RGR_FindBestRegression(times_back + inst->runs_samples,
+                                         offsets + inst->runs_samples, weights,
+                                         inst->n_samples, inst->runs_samples,
+                                         inst->min_samples,
+                                         &est_intercept, &est_slope, &est_var,
+                                         &est_intercept_sd, &est_slope_sd,
+                                         &best_start, &nruns, &degrees_of_freedom);
+
+  if (inst->regression_ok) {
+
+    old_skew = inst->skew;
+    old_freq = inst->estimated_frequency;
+  
+    inst->estimated_frequency = est_slope;
+    inst->estimated_frequency_sd = CLAMP(MIN_SKEW, est_slope_sd, MAX_SKEW);
+    inst->skew = est_slope_sd * RGR_GetTCoef(degrees_of_freedom);
+    inst->estimated_offset = est_intercept;
+    inst->offset_time = inst->sample_times[inst->last_sample];
+    inst->estimated_offset_sd = est_intercept_sd;
+    inst->std_dev = MAX(MIN_STDDEV, sqrt(est_var));
+    inst->nruns = nruns;
+
+    inst->skew = CLAMP(MIN_SKEW, inst->skew, MAX_SKEW);
+    stress = fabs(old_freq - inst->estimated_frequency) / old_skew;
+
+    DEBUG_LOG("off=%e freq=%e skew=%e n=%d bs=%d runs=%d asym=%f arun=%d",
+              inst->estimated_offset, inst->estimated_frequency, inst->skew,
+              inst->n_samples, best_start, inst->nruns,
+              inst->asymmetry, inst->asymmetry_run);
+
+    if (logfileid != -1) {
+      LOG_FileWrite(logfileid, "%s %-15s %10.3e %10.3e %10.3e %10.3e %10.3e %7.1e %3d %3d %3d %5.2f",
+              UTI_TimeToLogForm(inst->offset_time.tv_sec),
+              inst->ip_addr ? UTI_IPToString(inst->ip_addr) : UTI_RefidToString(inst->refid),
+              inst->std_dev,
+              inst->estimated_offset, inst->estimated_offset_sd,
+              inst->estimated_frequency, inst->skew, stress,
+              inst->n_samples, best_start, inst->nruns,
+              inst->asymmetry);
+    }
+
+    times_back_start = inst->runs_samples + best_start;
+    prune_register(inst, best_start);
+  } else {
+    inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
+    inst->skew = WORST_CASE_FREQ_BOUND;
+    inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
+    inst->std_dev = WORST_CASE_STDDEV_BOUND;
+    inst->nruns = 0;
+
+    if (inst->n_samples > 0) {
+      inst->estimated_offset = inst->offsets[inst->last_sample];
+      inst->offset_time = inst->sample_times[inst->last_sample];
+    } else {
+      inst->estimated_offset = 0.0;
+      UTI_ZeroTimespec(&inst->offset_time);
+    }
+
+    times_back_start = 0;
+  }
+
+  find_best_sample_index(inst, times_back + times_back_start);
+
+}
+
+/* ================================================== */
+/* Return the assumed worst case range of values that this source's
+   frequency lies within.  Frequency is defined as the amount of time
+   the local clock gains relative to the source per unit local clock
+   time. */
+void
+SST_GetFrequencyRange(SST_Stats inst,
+                      double *lo, double *hi)
+{
+  double freq, skew;
+  freq = inst->estimated_frequency;
+  skew = inst->skew;
+  *lo = freq - skew;
+  *hi = freq + skew;
+
+  /* This function is currently used only to determine the values of delta
+     and epsilon in the ntp_core module. Limit the skew to a reasonable maximum
+     to avoid failing the dispersion test too easily. */
+  if (skew > WORST_CASE_FREQ_BOUND) {
+    *lo = -WORST_CASE_FREQ_BOUND;
+    *hi = WORST_CASE_FREQ_BOUND;
+  }
+}
+
+/* ================================================== */
+
+void
+SST_GetSelectionData(SST_Stats inst, struct timespec *now,
+                     double *offset_lo_limit,
+                     double *offset_hi_limit,
+                     double *root_distance,
+                     double *std_dev,
+                     double *first_sample_ago,
+                     double *last_sample_ago,
+                     int *select_ok)
+{
+  double offset, sample_elapsed;
+  int i, j;
+  
+  if (!inst->n_samples) {
+    *select_ok = 0;
+    return;
+  }
+
+  i = get_runsbuf_index(inst, inst->best_single_sample);
+  j = get_buf_index(inst, inst->best_single_sample);
+
+  *std_dev = inst->std_dev;
+
+  sample_elapsed = fabs(UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]));
+  offset = inst->offsets[i] + sample_elapsed * inst->estimated_frequency;
+  *root_distance = 0.5 * inst->root_delays[j] +
+    inst->root_dispersions[j] + sample_elapsed * inst->skew;
+
+  *offset_lo_limit = offset - *root_distance;
+  *offset_hi_limit = offset + *root_distance;
+
+#if 0
+  double average_offset, elapsed;
+  int average_ok;
+  /* average_ok ignored for now */
+  elapsed = UTI_DiffTimespecsToDouble(now, &inst->offset_time);
+  average_offset = inst->estimated_offset + inst->estimated_frequency * elapsed;
+  if (fabs(average_offset - offset) <=
+      inst->peer_dispersions[j] + 0.5 * inst->peer_delays[i]) {
+    average_ok = 1;
+  } else {
+    average_ok = 0;
+  }
+#endif
+
+  i = get_runsbuf_index(inst, 0);
+  *first_sample_ago = UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]);
+  i = get_runsbuf_index(inst, inst->n_samples - 1);
+  *last_sample_ago = UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]);
+
+  *select_ok = inst->regression_ok;
+
+  /* If maxsamples is too small to have a successful regression, enable the
+     selection as a special case for a fast update/print-once reference mode */
+  if (!*select_ok && inst->n_samples < MIN_SAMPLES_FOR_REGRESS &&
+      inst->n_samples == inst->max_samples) {
+    *std_dev = CNF_GetMaxJitter();
+    *select_ok = 1;
+  }
+
+  DEBUG_LOG("n=%d off=%f dist=%f sd=%f first_ago=%f last_ago=%f selok=%d",
+            inst->n_samples, offset, *root_distance, *std_dev,
+            *first_sample_ago, *last_sample_ago, *select_ok);
+}
+
+/* ================================================== */
+
+void
+SST_GetTrackingData(SST_Stats inst, struct timespec *ref_time,
+                    double *average_offset, double *offset_sd,
+                    double *frequency, double *frequency_sd, double *skew,
+                    double *root_delay, double *root_dispersion)
+{
+  int i, j;
+  double elapsed_sample;
+
+  assert(inst->n_samples > 0);
+
+  i = get_runsbuf_index(inst, inst->best_single_sample);
+  j = get_buf_index(inst, inst->best_single_sample);
+
+  *ref_time = inst->offset_time;
+  *average_offset = inst->estimated_offset;
+  *offset_sd = inst->estimated_offset_sd;
+  *frequency = inst->estimated_frequency;
+  *frequency_sd = inst->estimated_frequency_sd;
+  *skew = inst->skew;
+  *root_delay = inst->root_delays[j];
+
+  elapsed_sample = UTI_DiffTimespecsToDouble(&inst->offset_time, &inst->sample_times[i]);
+  *root_dispersion = inst->root_dispersions[j] + inst->skew * elapsed_sample + *offset_sd;
+
+  DEBUG_LOG("n=%d off=%f offsd=%f freq=%e freqsd=%e skew=%e delay=%f disp=%f",
+            inst->n_samples, *average_offset, *offset_sd,
+            *frequency, *frequency_sd, *skew, *root_delay, *root_dispersion);
+}
+
+/* ================================================== */
+
+void
+SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doffset)
+{
+  int m, i;
+  double delta_time;
+  struct timespec *sample, prev;
+  double prev_offset, prev_freq;
+
+  if (!inst->n_samples)
+    return;
+
+  for (m = -inst->runs_samples; m < inst->n_samples; m++) {
+    i = get_runsbuf_index(inst, m);
+    sample = &inst->sample_times[i];
+    prev = *sample;
+    UTI_AdjustTimespec(sample, when, sample, &delta_time, dfreq, doffset);
+    inst->offsets[i] += delta_time;
+  }
+
+  /* Update the regression estimates */
+  prev = inst->offset_time;
+  prev_offset = inst->estimated_offset;
+  prev_freq = inst->estimated_frequency;
+  UTI_AdjustTimespec(&inst->offset_time, when, &inst->offset_time,
+      &delta_time, dfreq, doffset);
+  inst->estimated_offset += delta_time;
+  inst->estimated_frequency = (inst->estimated_frequency - dfreq) / (1.0 - dfreq);
+
+  DEBUG_LOG("n=%d m=%d old_off_time=%s new=%s old_off=%f new_off=%f old_freq=%.3f new_freq=%.3f",
+            inst->n_samples, inst->runs_samples,
+            UTI_TimespecToString(&prev), UTI_TimespecToString(&inst->offset_time),
+            prev_offset, inst->estimated_offset,
+            1.0e6 * prev_freq, 1.0e6 * inst->estimated_frequency);
+}
+
+/* ================================================== */
+
+void
+SST_CorrectOffset(SST_Stats inst, double doffset)
+{
+  int i;
+
+  if (!inst->n_samples)
+    return;
+
+  for (i = -inst->runs_samples; i < inst->n_samples; i++)
+    inst->offsets[get_runsbuf_index(inst, i)] += doffset;
+
+  inst->estimated_offset += doffset;
+}
+
+/* ================================================== */
+
+void 
+SST_AddDispersion(SST_Stats inst, double dispersion)
+{
+  int m, i;
+
+  for (m = 0; m < inst->n_samples; m++) {
+    i = get_buf_index(inst, m);
+    inst->root_dispersions[i] += dispersion;
+    inst->peer_dispersions[i] += dispersion;
+  }
+}
+
+/* ================================================== */
+
+double
+SST_PredictOffset(SST_Stats inst, struct timespec *when)
+{
+  double elapsed;
+  
+  if (inst->n_samples < MIN_SAMPLES_FOR_REGRESS) {
+    /* We don't have any useful statistics, and presumably the poll
+       interval is minimal.  We can't do any useful prediction other
+       than use the latest sample or zero if we don't have any samples */
+    if (inst->n_samples > 0) {
+      return inst->offsets[inst->last_sample];
+    } else {
+      return 0.0;
+    }
+  } else {
+    elapsed = UTI_DiffTimespecsToDouble(when, &inst->offset_time);
+    return inst->estimated_offset + elapsed * inst->estimated_frequency;
+  }
+
+}
+
+/* ================================================== */
+
+double
+SST_MinRoundTripDelay(SST_Stats inst)
+{
+  if (inst->fixed_min_delay > 0.0)
+    return inst->fixed_min_delay;
+
+  if (!inst->n_samples)
+    return DBL_MAX;
+
+  return inst->peer_delays[inst->min_delay_sample];
+}
+
+/* ================================================== */
+
+int
+SST_GetDelayTestData(SST_Stats inst, struct timespec *sample_time,
+                     double *last_sample_ago, double *predicted_offset,
+                     double *min_delay, double *skew, double *std_dev)
+{
+  if (inst->n_samples < 6)
+    return 0;
+
+  *last_sample_ago = UTI_DiffTimespecsToDouble(sample_time, &inst->offset_time);
+  *predicted_offset = inst->estimated_offset +
+                      *last_sample_ago * inst->estimated_frequency;
+  *min_delay = SST_MinRoundTripDelay(inst);
+  *skew = inst->skew;
+  *std_dev = inst->std_dev;
+
+  return 1;
+}
+
+/* ================================================== */
+/* This is used to save the register to a file, so that we can reload
+   it after restarting the daemon */
+
+int
+SST_SaveToFile(SST_Stats inst, FILE *out)
+{
+  int m, i, j;
+
+  if (inst->n_samples < 1)
+    return 0;
+
+  if (fprintf(out, "%d %d\n", inst->n_samples, inst->asymmetry_run) < 0)
+    return 0;
+
+  for(m = 0; m < inst->n_samples; m++) {
+    i = get_runsbuf_index(inst, m);
+    j = get_buf_index(inst, m);
+
+    if (fprintf(out, "%s %.6e %.6e %.6e %.6e %.6e %.6e\n",
+                UTI_TimespecToString(&inst->sample_times[i]),
+                inst->offsets[i], inst->orig_offsets[j],
+                inst->peer_delays[i], inst->peer_dispersions[j],
+                inst->root_delays[j], inst->root_dispersions[j]) < 0)
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+/* This is used to reload samples from a file */
+
+int
+SST_LoadFromFile(SST_Stats inst, FILE *in)
+{
+  int i, n_samples, arun;
+  struct timespec now;
+  double sample_time;
+  char line[256];
+
+  if (!fgets(line, sizeof (line), in) ||
+      sscanf(line, "%d %d", &n_samples, &arun) != 2 ||
+      n_samples < 1 || n_samples > MAX_SAMPLES)
+    return 0;
+
+  SST_ResetInstance(inst);
+
+  LCL_ReadCookedTime(&now, NULL);
+
+  for (i = 0; i < n_samples; i++) {
+    if (!fgets(line, sizeof (line), in) ||
+        sscanf(line, "%lf %lf %lf %lf %lf %lf %lf",
+               &sample_time, &inst->offsets[i], &inst->orig_offsets[i],
+               &inst->peer_delays[i], &inst->peer_dispersions[i],
+               &inst->root_delays[i], &inst->root_dispersions[i]) != 7)
+      return 0;
+
+    if (!UTI_IsTimeOffsetSane(&now, sample_time - UTI_TimespecToDouble(&now)))
+      return 0;
+
+    /* Some resolution is lost in the double format, but that's ok */
+    UTI_DoubleToTimespec(sample_time, &inst->sample_times[i]);
+
+    /* Make sure the samples are sane and they are in order */
+    if (!UTI_IsTimeOffsetSane(&inst->sample_times[i], -inst->offsets[i]) ||
+        UTI_CompareTimespecs(&now, &inst->sample_times[i]) < 0 ||
+        !(fabs(inst->peer_delays[i]) < 1.0e6 && fabs(inst->peer_dispersions[i]) < 1.0e6 &&
+          fabs(inst->root_delays[i]) < 1.0e6 && fabs(inst->root_dispersions[i]) < 1.0e6) ||
+        (i > 0 && UTI_CompareTimespecs(&inst->sample_times[i],
+                                       &inst->sample_times[i - 1]) <= 0))
+      return 0;
+  }
+
+  inst->n_samples = n_samples;
+  inst->last_sample = inst->n_samples - 1;
+  inst->asymmetry_run = CLAMP(-MAX_ASYMMETRY_RUN, arun, MAX_ASYMMETRY_RUN);
+
+  find_min_delay_sample(inst);
+  SST_DoNewRegression(inst);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SST_DoSourceReport(SST_Stats inst, RPT_SourceReport *report, struct timespec *now)
+{
+  int i, j;
+  struct timespec last_sample_time;
+
+  if (inst->n_samples > 0) {
+    i = get_runsbuf_index(inst, inst->n_samples - 1);
+    j = get_buf_index(inst, inst->n_samples - 1);
+    report->orig_latest_meas = inst->orig_offsets[j];
+    report->latest_meas = inst->offsets[i];
+    report->latest_meas_err = 0.5*inst->root_delays[j] + inst->root_dispersions[j];
+
+    /* Align the sample time to reduce the leak of the receive timestamp */
+    last_sample_time = inst->sample_times[i];
+    last_sample_time.tv_nsec = 0;
+    report->latest_meas_ago = UTI_DiffTimespecsToDouble(now, &last_sample_time);
+  } else {
+    report->latest_meas_ago = (uint32_t)-1;
+    report->orig_latest_meas = 0;
+    report->latest_meas = 0;
+    report->latest_meas_err = 0;
+    report->stratum = 0;
+  }
+}
+
+/* ================================================== */
+
+int
+SST_Samples(SST_Stats inst)
+{
+  return inst->n_samples;
+}
+
+/* ================================================== */
+
+int
+SST_GetMinSamples(SST_Stats inst)
+{
+  return inst->min_samples;
+}
+
+/* ================================================== */
+
+void
+SST_DoSourcestatsReport(SST_Stats inst, RPT_SourcestatsReport *report, struct timespec *now)
+{
+  double dspan;
+  double elapsed, sample_elapsed;
+  int bi, bj;
+
+  report->n_samples = inst->n_samples;
+  report->n_runs = inst->nruns;
+
+  if (inst->n_samples > 0) {
+    bi = get_runsbuf_index(inst, inst->best_single_sample);
+    bj = get_buf_index(inst, inst->best_single_sample);
+
+    dspan = UTI_DiffTimespecsToDouble(&inst->sample_times[inst->last_sample],
+                                      &inst->sample_times[get_runsbuf_index(inst, 0)]);
+    elapsed = UTI_DiffTimespecsToDouble(now, &inst->offset_time);
+    sample_elapsed = UTI_DiffTimespecsToDouble(now, &inst->sample_times[bi]);
+
+    report->span_seconds = round(dspan);
+    report->est_offset = inst->estimated_offset + elapsed * inst->estimated_frequency;
+    report->est_offset_err = inst->estimated_offset_sd + sample_elapsed * inst->skew +
+                             (0.5 * inst->root_delays[bj] + inst->root_dispersions[bj]);
+  } else {
+    report->span_seconds = 0;
+    report->est_offset = 0;
+    report->est_offset_err = 0;
+  }
+
+  report->resid_freq_ppm = 1.0e6 * inst->estimated_frequency;
+  report->skew_ppm = 1.0e6 * inst->skew;
+  report->sd = inst->std_dev;
+}
+
+/* ================================================== */
+
+double
+SST_GetJitterAsymmetry(SST_Stats inst)
+{
+  return inst->asymmetry;
+}
+
+/* ================================================== */
diff --git a/sourcestats.h b/sourcestats.h
new file mode 100644
index 0000000..e10f425
--- /dev/null
+++ b/sourcestats.h
@@ -0,0 +1,141 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for module that deals with the measurements and statistics of
+  each of the sources. */
+
+#ifndef GOT_SOURCESTATS_H
+#define GOT_SOURCESTATS_H
+
+#include "sysincl.h"
+
+#include "reports.h"
+
+typedef struct SST_Stats_Record *SST_Stats;
+
+/* Init and fini functions */
+extern void SST_Initialise(void);
+extern void SST_Finalise(void);
+
+/* This function creates a new instance of the statistics handler */
+extern SST_Stats SST_CreateInstance(uint32_t refid, IPAddr *addr,
+                                    int min_samples, int max_samples,
+                                    double min_delay, double asymmetry);
+
+/* This function deletes an instance of the statistics handler. */
+extern void SST_DeleteInstance(SST_Stats inst);
+
+/* This function resets an instance */
+extern void SST_ResetInstance(SST_Stats inst);
+
+/* This function changes the reference ID and IP address */
+extern void SST_SetRefid(SST_Stats inst, uint32_t refid, IPAddr *addr);
+
+/* This function accumulates a single sample into the statistics handler */
+extern void SST_AccumulateSample(SST_Stats inst, NTP_Sample *sample);
+
+/* This function runs the linear regression operation on the data.  It
+   finds the set of most recent samples that give the tightest
+   confidence interval for the frequency, and truncates the register
+   down to that number of samples. */
+extern void SST_DoNewRegression(SST_Stats inst);
+
+/* Return the assumed worst case range of values that this source's
+   frequency lies within.  Frequency is defined as the amount of time
+   the local clock gains relative to the source per unit local clock
+   time. */
+extern void SST_GetFrequencyRange(SST_Stats inst, double *lo, double *hi);
+
+/* Get data needed for selection */
+extern void
+SST_GetSelectionData(SST_Stats inst, struct timespec *now,
+                     double *offset_lo_limit,
+                     double *offset_hi_limit,
+                     double *root_distance,
+                     double *variance,
+                     double *first_sample_ago,
+                     double *last_sample_ago,
+                     int *select_ok);
+
+/* Get data needed when setting up tracking on this source */
+extern void
+SST_GetTrackingData(SST_Stats inst, struct timespec *ref_time,
+                    double *average_offset, double *offset_sd,
+                    double *frequency, double *frequency_sd, double *skew,
+                    double *root_delay, double *root_dispersion);
+
+/* This routine is called when the local machine clock parameters are
+   changed.  It adjusts all existing samples that we are holding for
+   each peer so that it looks like they were made under the new clock
+   regime rather than the old one.
+
+   when = cooked local time when the change occurs
+
+   dfreq = delta frequency. positive means the clock has been adjusted
+   because it was previously gaining time relative to the external
+   reference(s).
+
+   doffset = offset slewed onto local clock.  positive => local clock
+   has been made fast by that amount.
+
+*/
+
+extern void SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doffset);
+
+/* This routine corrects already accumulated samples to improve the
+   frequency estimate when a new sample is accumulated */
+extern void SST_CorrectOffset(SST_Stats inst, double doffset);
+
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+extern void SST_AddDispersion(SST_Stats inst, double dispersion);
+
+/* Predict the offset of the local clock relative to a given source at
+   a given local cooked time. Positive indicates local clock is FAST
+   relative to reference. */
+extern double SST_PredictOffset(SST_Stats inst, struct timespec *when);
+
+/* Find the minimum round trip delay in the register */
+extern double SST_MinRoundTripDelay(SST_Stats inst);
+
+/* Get data needed for testing NTP delay */
+extern int SST_GetDelayTestData(SST_Stats inst, struct timespec *sample_time,
+                                double *last_sample_ago, double *predicted_offset,
+                                double *min_delay, double *skew, double *std_dev);
+
+extern int SST_SaveToFile(SST_Stats inst, FILE *out);
+
+extern int SST_LoadFromFile(SST_Stats inst, FILE *in);
+
+extern void SST_DoSourceReport(SST_Stats inst, RPT_SourceReport *report, struct timespec *now);
+
+extern void SST_DoSourcestatsReport(SST_Stats inst, RPT_SourcestatsReport *report, struct timespec *now);
+
+extern int SST_Samples(SST_Stats inst);
+
+extern int SST_GetMinSamples(SST_Stats inst);
+
+extern double SST_GetJitterAsymmetry(SST_Stats inst);
+
+#endif /* GOT_SOURCESTATS_H */
+
diff --git a/srcparams.h b/srcparams.h
new file mode 100644
index 0000000..31baed7
--- /dev/null
+++ b/srcparams.h
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file defining parameters that can be set on a per source basis
+  */
+
+#ifndef GOT_SRCPARAMS_H
+#define GOT_SRCPARAMS_H
+
+#include "sources.h"
+
+typedef enum {
+  SRC_OFFLINE,
+  SRC_ONLINE,
+  SRC_MAYBE_ONLINE,
+} SRC_Connectivity;
+
+typedef struct {
+  int minpoll;
+  int maxpoll;
+  SRC_Connectivity connectivity;
+  int auto_offline;
+  int presend_minpoll;
+  int burst;
+  int iburst;
+  int min_stratum;
+  int poll_target;
+  int version;
+  int max_sources;
+  int min_samples;
+  int max_samples;
+  int filter_length;
+  int interleaved;
+  int sel_options;
+  int nts;
+  int nts_port;
+  int copy;
+  int ext_fields;
+  uint32_t authkey;
+  uint32_t cert_set;
+  double max_delay;
+  double max_delay_ratio;
+  double max_delay_dev_ratio;
+  double max_delay_quant;
+  double min_delay;
+  double asymmetry;
+  double offset;
+} SourceParameters;
+
+#define SRC_DEFAULT_PORT 123
+#define SRC_DEFAULT_MINPOLL 6
+#define SRC_DEFAULT_MAXPOLL 10
+#define SRC_DEFAULT_PRESEND_MINPOLL 100
+#define SRC_DEFAULT_MAXDELAY 3.0
+#define SRC_DEFAULT_MAXDELAYRATIO 0.0
+#define SRC_DEFAULT_MAXDELAYDEVRATIO 10.0
+#define SRC_DEFAULT_MINSTRATUM 0
+#define SRC_DEFAULT_POLLTARGET 8
+#define SRC_DEFAULT_MAXSOURCES 4
+#define SRC_DEFAULT_MINSAMPLES (-1)
+#define SRC_DEFAULT_MAXSAMPLES (-1)
+#define SRC_DEFAULT_ASYMMETRY 1.0
+#define SRC_DEFAULT_NTSPORT 4460
+#define SRC_DEFAULT_CERTSET 0
+#define INACTIVE_AUTHKEY 0
+
+/* Flags for source selection */
+#define SRC_SELECT_NOSELECT 0x1
+#define SRC_SELECT_PREFER 0x2
+#define SRC_SELECT_TRUST 0x4
+#define SRC_SELECT_REQUIRE 0x8
+
+#endif /* GOT_SRCPARAMS_H */
diff --git a/stubs.c b/stubs.c
new file mode 100644
index 0000000..cb7b9a6
--- /dev/null
+++ b/stubs.c
@@ -0,0 +1,567 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Function replacements needed when optional features are disabled.
+
+  */
+
+#include "config.h"
+
+#include "clientlog.h"
+#include "cmac.h"
+#include "cmdmon.h"
+#include "keys.h"
+#include "logging.h"
+#include "manual.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "nameserv_async.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "ntp_sources.h"
+#include "ntp_signd.h"
+#include "nts_ke_client.h"
+#include "nts_ke_server.h"
+#include "nts_ntp_client.h"
+#include "nts_ntp_server.h"
+#include "privops.h"
+#include "refclock.h"
+#include "sched.h"
+#include "util.h"
+
+#if defined(FEAT_NTP) && !defined(FEAT_ASYNCDNS)
+
+/* This is a blocking implementation used when asynchronous resolving is not available */
+
+struct DNS_Async_Instance {
+  const char *name;
+  DNS_NameResolveHandler handler;
+  void *arg;
+  int pipe[2];
+};
+
+static void
+resolve_name(int fd, int event, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+  IPAddr addrs[DNS_MAX_ADDRESSES];
+  DNS_Status status;
+  int i;
+
+  inst = (struct DNS_Async_Instance *)anything;
+
+  SCH_RemoveFileHandler(inst->pipe[0]);
+  close(inst->pipe[0]);
+  close(inst->pipe[1]);
+
+  status = PRV_Name2IPAddress(inst->name, addrs, DNS_MAX_ADDRESSES);
+
+  for (i = 0; status == DNS_Success && i < DNS_MAX_ADDRESSES &&
+       addrs[i].family != IPADDR_UNSPEC; i++)
+    ;
+
+  (inst->handler)(status, i, addrs, inst->arg);
+
+  Free(inst);
+}
+
+void
+DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+
+  inst = MallocNew(struct DNS_Async_Instance);
+  inst->name = name;
+  inst->handler = handler;
+  inst->arg = anything;
+
+  if (pipe(inst->pipe))
+    LOG_FATAL("pipe() failed");
+
+  UTI_FdSetCloexec(inst->pipe[0]);
+  UTI_FdSetCloexec(inst->pipe[1]);
+
+  SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, resolve_name, inst);
+
+  if (write(inst->pipe[1], "", 1) < 0)
+    ;
+}
+
+#endif /* !FEAT_ASYNCDNS */
+
+#ifndef FEAT_CMDMON
+
+void
+CAM_Initialise(void)
+{
+}
+
+void
+CAM_Finalise(void)
+{
+}
+
+void
+CAM_OpenUnixSocket(void)
+{
+}
+
+int
+CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+{
+  return 1;
+}
+
+void
+MNL_Initialise(void)
+{
+}
+
+void
+MNL_Finalise(void)
+{
+}
+
+#endif /* !FEAT_CMDMON */
+
+#ifndef FEAT_NTP
+
+void
+NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval)
+{
+}
+
+void
+NCR_Initialise(void)
+{
+}
+
+void
+NCR_Finalise(void)
+{
+}
+
+int
+NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+{
+  return 1;
+}
+
+int
+NCR_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return 0;
+}
+
+void
+NIO_Initialise(void)
+{
+}
+
+void
+NIO_Finalise(void)
+{
+}
+
+void
+NSR_Initialise(void)
+{
+}
+
+void
+NSR_Finalise(void)
+{
+}
+
+NSR_Status
+NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+              SourceParameters *params, uint32_t *conf_id)
+{
+  return NSR_TooManySources;
+}
+
+NSR_Status
+NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                    SourceParameters *params, uint32_t *conf_id)
+{
+  return NSR_TooManySources;
+}
+
+NSR_Status
+NSR_RemoveSource(IPAddr *address)
+{
+  return NSR_NoSuchSource;
+}
+
+void
+NSR_RemoveSourcesById(uint32_t conf_id)
+{
+}
+
+void
+NSR_RemoveAllSources(void)
+{
+}
+
+void
+NSR_HandleBadSource(IPAddr *address)
+{
+}
+
+void
+NSR_RefreshAddresses(void)
+{
+}
+
+char *
+NSR_GetName(IPAddr *address)
+{
+  return NULL;
+}
+
+void
+NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler)
+{
+  if (handler)
+    (handler)();
+}
+
+void
+NSR_ResolveSources(void)
+{
+}
+
+void NSR_StartSources(void)
+{
+}
+
+void NSR_AutoStartSources(void)
+{
+}
+
+int
+NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples,
+                        IPAddr *mask, IPAddr *address)
+{
+  return 0;
+}
+
+uint32_t
+NSR_GetLocalRefid(IPAddr *address)
+{
+  return 0;
+}
+
+int
+NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMinpoll(IPAddr *address, int new_minpoll)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_dev_ratio)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum)
+{
+  return 0;
+}
+
+int
+NSR_ModifyPolltarget(IPAddr *address, int new_poll_target)
+{
+  return 0;
+}
+
+void
+NSR_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  memset(report, 0, sizeof (*report));
+}
+  
+int
+NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report)
+{
+  return 0;
+}
+
+int
+NSR_GetNTPReport(RPT_NTPReport *report)
+{
+  return 0;
+}
+
+void
+NSR_GetActivityReport(RPT_ActivityReport *report)
+{
+  memset(report, 0, sizeof (*report));
+}
+
+void
+NSR_DumpAuthData(void)
+{
+}
+
+#ifndef FEAT_CMDMON
+
+void
+CLG_Initialise(void)
+{
+}
+
+void
+CLG_Finalise(void)
+{
+}
+
+void
+DNS_SetAddressFamily(int family)
+{
+}
+
+DNS_Status
+DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  return DNS_Failure;
+}
+
+void
+KEY_Initialise(void)
+{
+}
+
+void
+KEY_Finalise(void)
+{
+}
+
+#endif /* !FEAT_CMDMON */
+#endif /* !FEAT_NTP */
+
+#ifndef FEAT_REFCLOCK
+void
+RCL_Initialise(void)
+{
+}
+
+void
+RCL_Finalise(void)
+{
+}
+
+int
+RCL_AddRefclock(RefclockParameters *params)
+{
+  return 0;
+}
+
+void
+RCL_StartRefclocks(void)
+{
+}
+
+void
+RCL_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  memset(report, 0, sizeof (*report));
+}
+
+#endif /* !FEAT_REFCLOCK */
+
+#ifndef FEAT_SIGND
+
+void
+NSD_Initialise(void)
+{
+}
+
+void
+NSD_Finalise(void)
+{
+}
+
+int
+NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                      NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
+{
+  return 0;
+}
+
+#endif /* !FEAT_SIGND */
+
+#ifndef HAVE_CMAC
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  return 0;
+}
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  return NULL;
+}
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  return 0;
+}
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+}
+
+#endif /* !HAVE_CMAC */
+
+#ifndef FEAT_NTS
+
+void
+NNS_Initialise(void)
+{
+}
+
+void
+NNS_Finalise(void)
+{
+}
+
+int
+NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
+{
+  *kod = 0;
+  return 0;
+}
+
+int
+NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                         NTP_Packet *response, NTP_PacketInfo *res_info,
+                         uint32_t kod)
+{
+  return 0;
+}
+
+NNC_Instance
+NNC_CreateInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set,
+                   uint16_t ntp_port)
+{
+  return NULL;
+}
+
+void
+NNC_DestroyInstance(NNC_Instance inst)
+{
+}
+
+int
+NNC_PrepareForAuth(NNC_Instance inst)
+{
+  return 1;
+}
+
+int
+NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  static int logged = 0;
+
+  LOG(logged ? LOGS_DEBUG : LOGS_WARN, "Missing NTS support");
+  logged = 1;
+  return 0;
+}
+
+int
+NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  return 0;
+}
+
+void
+NNC_ChangeAddress(NNC_Instance inst, IPAddr *address)
+{
+}
+
+void
+NNC_DumpData(NNC_Instance inst)
+{
+}
+
+void
+NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report)
+{
+}
+
+void
+NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level)
+{
+}
+
+void
+NKS_Initialise(void)
+{
+}
+
+void
+NKS_Finalise(void)
+{
+}
+
+void
+NKS_DumpKeys(void)
+{
+}
+
+void
+NKS_ReloadKeys(void)
+{
+}
+
+#endif /* !FEAT_NTS */
diff --git a/sys.c b/sys.c
new file mode 100644
index 0000000..1a1a432
--- /dev/null
+++ b/sys.c
@@ -0,0 +1,150 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains all the conditionally compiled bits that pull
+  in the various operating-system specific modules
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys.h"
+#include "sys_null.h"
+#include "logging.h"
+
+#if defined(LINUX)
+#include "sys_linux.h"
+#include "sys_posix.h"
+#elif defined(SOLARIS)
+#include "sys_solaris.h"
+#include "sys_posix.h"
+#elif defined(NETBSD) || defined(FREEBSD)
+#include "sys_netbsd.h"
+#include "sys_posix.h"
+#elif defined(MACOSX)
+#include "sys_macosx.h"
+#endif
+
+/* ================================================== */
+
+static int null_driver;
+
+/* ================================================== */
+
+void
+SYS_Initialise(int clock_control)
+{
+  null_driver = !clock_control;
+  if (null_driver) {
+    SYS_Null_Initialise();
+    return;
+  }
+#if defined(LINUX)
+  SYS_Linux_Initialise();
+#elif defined(SOLARIS)
+  SYS_Solaris_Initialise();
+#elif defined(NETBSD) || defined(FREEBSD)
+  SYS_NetBSD_Initialise();
+#elif defined(MACOSX)
+  SYS_MacOSX_Initialise();
+#else
+#error Unknown system
+#endif
+}
+
+/* ================================================== */
+
+void
+SYS_Finalise(void)
+{
+  if (null_driver) {
+    SYS_Null_Finalise();
+    return;
+  }
+#if defined(LINUX)
+  SYS_Linux_Finalise();
+#elif defined(SOLARIS)
+  SYS_Solaris_Finalise();
+#elif defined(NETBSD) || defined(FREEBSD)
+  SYS_NetBSD_Finalise();
+#elif defined(MACOSX)
+  SYS_MacOSX_Finalise();
+#else
+#error Unknown system
+#endif
+}
+
+/* ================================================== */
+
+void SYS_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+#if defined(LINUX) && defined (FEAT_PRIVDROP)
+  SYS_Linux_DropRoot(uid, gid, context, !null_driver);
+#elif defined(SOLARIS) && defined(FEAT_PRIVDROP)
+  SYS_Solaris_DropRoot(uid, gid, context);
+#elif (defined(NETBSD) || defined(FREEBSD)) && defined(FEAT_PRIVDROP)
+  SYS_NetBSD_DropRoot(uid, gid, context, !null_driver);
+#elif defined(MACOSX) && defined(FEAT_PRIVDROP)
+  SYS_MacOSX_DropRoot(uid, gid, context);
+#else
+  LOG_FATAL("dropping root privileges not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_EnableSystemCallFilter(int level, SYS_ProcessContext context)
+{
+#if defined(LINUX) && defined(FEAT_SCFILTER)
+  SYS_Linux_EnableSystemCallFilter(level, context);
+#else
+  LOG_FATAL("system call filter not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_SetScheduler(int SchedPriority)
+{
+#if defined(MACOSX)
+  SYS_MacOSX_SetScheduler(SchedPriority);
+#elif defined(HAVE_PTHREAD_SETSCHEDPARAM)
+  SYS_Posix_SetScheduler(SchedPriority);
+#else
+  LOG_FATAL("scheduler priority setting not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_LockMemory(void)
+{
+#if defined(HAVE_MLOCKALL)
+  SYS_Posix_MemLockAll();
+#else
+  LOG_FATAL("memory locking not supported");
+#endif
+}
+
+/* ================================================== */
diff --git a/sys.h b/sys.h
new file mode 100644
index 0000000..9272daf
--- /dev/null
+++ b/sys.h
@@ -0,0 +1,53 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header for the file that links in the operating system-
+  specific parts of the software
+
+*/
+
+#ifndef GOT_SYS_H
+#define GOT_SYS_H
+
+/* Called at the start of the run to do initialisation */
+extern void SYS_Initialise(int clock_control);
+
+/* Called at the end of the run to do final clean-up */
+extern void SYS_Finalise(void);
+
+typedef enum {
+  SYS_MAIN_PROCESS,
+  SYS_NTSKE_HELPER,
+} SYS_ProcessContext;
+
+/* Switch to the specified user and group in given context */
+extern void SYS_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+
+/* Enable a system call filter to allow only system calls
+   which chronyd normally needs after initialization */
+extern void SYS_EnableSystemCallFilter(int level, SYS_ProcessContext context);
+
+extern void SYS_SetScheduler(int SchedPriority);
+extern void SYS_LockMemory(void);
+
+#endif /* GOT_SYS_H */
diff --git a/sys_generic.c b/sys_generic.c
new file mode 100644
index 0000000..5c42df1
--- /dev/null
+++ b/sys_generic.c
@@ -0,0 +1,449 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Generic driver functions to complete system-specific drivers
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_generic.h"
+
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "privops.h"
+#include "sched.h"
+#include "util.h"
+
+/* ================================================== */
+
+/* System clock drivers */
+static lcl_ReadFrequencyDriver drv_read_freq;
+static lcl_SetFrequencyDriver drv_set_freq;
+static lcl_SetSyncStatusDriver drv_set_sync_status;
+static lcl_AccrueOffsetDriver drv_accrue_offset;
+static lcl_OffsetCorrectionDriver drv_get_offset_correction;
+
+/* Current frequency as requested by the local module (in ppm) */
+static double base_freq;
+
+/* Maximum frequency that can be set by drv_set_freq (in ppm) */
+static double max_freq;
+
+/* Maximum expected delay in the actual frequency change (e.g. kernel ticks)
+   in local time */
+static double max_freq_change_delay;
+
+/* Maximum allowed frequency offset relative to the base frequency */
+static double max_corr_freq;
+
+/* Amount of outstanding offset to process */
+static double offset_register;
+
+/* Minimum offset to correct */
+#define MIN_OFFSET_CORRECTION 1.0e-9
+
+/* Current frequency offset between base_freq and the real clock frequency
+   as set by drv_set_freq (not in ppm) */
+static double slew_freq;
+
+/* Time (raw) of last update of slewing frequency and offset */
+static struct timespec slew_start;
+
+/* Limits for the slew length */
+#define MIN_SLEW_DURATION 1.0
+#define MAX_SLEW_DURATION 1.0e4
+
+/* Scheduler timeout ID for ending of the currently running slew */
+static SCH_TimeoutID slew_timeout_id;
+
+/* Scheduled duration of the currently running slew */
+static double slew_duration;
+
+/* Expected delay in ending of the slew due to process scheduling and
+   execution time, tracked as a decaying maximum value */
+static double slew_excess_duration;
+
+/* Maximum accepted excess duration to ignore large jumps after resuming
+   suspended system and other reasons (which should be handled in the
+   scheduler), a constant to determine the minimum slew duration to avoid
+   oscillations due to the excess, and the decay constant */
+#define MAX_SLEW_EXCESS_DURATION 100.0
+#define MIN_SLEW_DURATION_EXCESS_RATIO 5.0
+#define SLEW_EXCESS_DURATION_DECAY 0.9
+
+/* Suggested offset correction rate (correction time * offset) */
+static double correction_rate;
+
+/* Maximum expected offset correction error caused by delayed change in the
+   real frequency of the clock */
+static double slew_error;
+
+/* Minimum offset that the system driver can slew faster than the maximum
+   frequency offset that it allows to be set directly */
+static double fastslew_min_offset;
+
+/* Maximum slew rate of the system driver */
+static double fastslew_max_rate;
+
+/* Flag indicating that the system driver is currently slewing */
+static int fastslew_active;
+
+/* ================================================== */
+
+static void handle_end_of_slew(void *anything);
+static void update_slew(void);
+
+/* ================================================== */
+/* Adjust slew_start on clock step */
+
+static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type == LCL_ChangeStep) {
+    UTI_AddDoubleToTimespec(&slew_start, -doffset, &slew_start);
+  }
+}
+
+/* ================================================== */
+
+static void
+start_fastslew(void)
+{
+  if (!drv_accrue_offset)
+    return;
+
+  drv_accrue_offset(offset_register, 0.0);
+
+  DEBUG_LOG("fastslew offset=%e", offset_register);
+
+  offset_register = 0.0;
+  fastslew_active = 1;
+}
+
+/* ================================================== */
+
+static void
+stop_fastslew(struct timespec *now)
+{
+  double corr;
+
+  if (!drv_get_offset_correction || !fastslew_active)
+    return;
+
+  /* Cancel the remaining offset */
+  drv_get_offset_correction(now, &corr, NULL);
+  drv_accrue_offset(corr, 0.0);
+  offset_register -= corr;
+}
+
+/* ================================================== */
+
+static double
+clamp_freq(double freq)
+{
+  if (freq > max_freq)
+    return max_freq;
+  if (freq < -max_freq)
+    return -max_freq;
+  return freq;
+}
+
+/* ================================================== */
+/* End currently running slew and start a new one */
+
+static void
+update_slew(void)
+{
+  double old_slew_freq, total_freq, corr_freq, duration, excess_duration;
+  struct timespec now, end_of_slew;
+
+  /* Remove currently running timeout */
+  SCH_RemoveTimeout(slew_timeout_id);
+
+  LCL_ReadRawTime(&now);
+
+  /* Adjust the offset register by achieved slew */
+  duration = UTI_DiffTimespecsToDouble(&now, &slew_start);
+  offset_register -= slew_freq * duration;
+
+  stop_fastslew(&now);
+
+  /* Update the maximum excess duration, decaying even when the slew did
+     not time out (i.e. frequency was set or offset accrued), but add a small
+     value to avoid denormals */
+  slew_excess_duration = (slew_excess_duration + 1.0e-9) * SLEW_EXCESS_DURATION_DECAY;
+  excess_duration = duration - slew_duration;
+  if (slew_excess_duration < excess_duration &&
+      excess_duration <= MAX_SLEW_EXCESS_DURATION)
+    slew_excess_duration = excess_duration;
+
+  /* Calculate the duration of the new slew, considering the current correction
+     rate and previous delays in stopping of the slew */
+  if (fabs(offset_register) < MIN_OFFSET_CORRECTION) {
+    duration = MAX_SLEW_DURATION;
+  } else {
+    duration = correction_rate / fabs(offset_register);
+    if (duration < MIN_SLEW_DURATION)
+      duration = MIN_SLEW_DURATION;
+    if (duration < MIN_SLEW_DURATION_EXCESS_RATIO * slew_excess_duration)
+      duration = MIN_SLEW_DURATION_EXCESS_RATIO * slew_excess_duration;
+  }
+
+  /* Get frequency offset needed to slew the offset in the duration
+     and clamp it to the allowed maximum */
+  corr_freq = offset_register / duration;
+  if (corr_freq < -max_corr_freq)
+    corr_freq = -max_corr_freq;
+  else if (corr_freq > max_corr_freq)
+    corr_freq = max_corr_freq;
+
+  /* Let the system driver perform the slew if the requested frequency
+     offset is too large for the frequency driver */
+  if (drv_accrue_offset && fabs(corr_freq) >= fastslew_max_rate &&
+      fabs(offset_register) > fastslew_min_offset) {
+    start_fastslew();
+    corr_freq = 0.0;
+  }
+
+  /* Get the new real frequency and clamp it */
+  total_freq = clamp_freq(base_freq + corr_freq * (1.0e6 - base_freq));
+
+  /* Set the new frequency (the actual frequency returned by the call may be
+     slightly different from the requested frequency due to rounding) */
+  total_freq = (*drv_set_freq)(total_freq);
+
+  /* Compute the new slewing frequency, it's relative to the real frequency to
+     make the calculation in offset_convert() cheaper */
+  old_slew_freq = slew_freq;
+  slew_freq = (total_freq - base_freq) / (1.0e6 - total_freq);
+
+  /* Compute the dispersion introduced by changing frequency and add it
+     to all statistics held at higher levels in the system */
+  slew_error = fabs((old_slew_freq - slew_freq) * max_freq_change_delay);
+  if (slew_error >= MIN_OFFSET_CORRECTION)
+    lcl_InvokeDispersionNotifyHandlers(slew_error);
+
+  /* Compute the duration of the slew and clamp it.  If the slewing frequency
+     is zero or has wrong sign (e.g. due to rounding in the frequency driver or
+     when base_freq is larger than max_freq, or fast slew is active), use the
+     maximum timeout and try again on the next update. */
+  if (fabs(offset_register) < MIN_OFFSET_CORRECTION ||
+      offset_register * slew_freq <= 0.0) {
+    duration = MAX_SLEW_DURATION;
+  } else {
+    duration = offset_register / slew_freq;
+    if (duration < MIN_SLEW_DURATION)
+      duration = MIN_SLEW_DURATION;
+    else if (duration > MAX_SLEW_DURATION)
+      duration = MAX_SLEW_DURATION;
+  }
+
+  /* Restart timer for the next update */
+  UTI_AddDoubleToTimespec(&now, duration, &end_of_slew);
+  slew_timeout_id = SCH_AddTimeout(&end_of_slew, handle_end_of_slew, NULL);
+  slew_start = now;
+  slew_duration = duration;
+
+  DEBUG_LOG("slew offset=%e corr_rate=%e base_freq=%f total_freq=%f slew_freq=%e"
+            " duration=%f excess=%f slew_error=%e",
+            offset_register, correction_rate, base_freq, total_freq, slew_freq,
+            slew_duration, slew_excess_duration, slew_error);
+}
+
+/* ================================================== */
+
+static void
+handle_end_of_slew(void *anything)
+{
+  slew_timeout_id = 0;
+  update_slew();
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return base_freq;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  base_freq = freq_ppm;
+  update_slew();
+
+  return base_freq;
+}
+
+/* ================================================== */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  offset_register += offset;
+  correction_rate = corr_rate;
+
+  update_slew();
+}
+
+/* ================================================== */
+/* Determine the correction to generate the cooked time for given raw time */
+
+static void
+offset_convert(struct timespec *raw,
+               double *corr, double *err)
+{
+  double duration, fastslew_corr, fastslew_err;
+
+  duration = UTI_DiffTimespecsToDouble(raw, &slew_start);
+
+  if (drv_get_offset_correction && fastslew_active) {
+    drv_get_offset_correction(raw, &fastslew_corr, &fastslew_err);
+    if (fastslew_corr == 0.0 && fastslew_err == 0.0)
+      fastslew_active = 0;
+  } else {
+    fastslew_corr = fastslew_err = 0.0;
+  }
+
+  *corr = slew_freq * duration + fastslew_corr - offset_register;
+
+  if (err) {
+    *err = fastslew_err;
+    if (fabs(duration) <= max_freq_change_delay)
+      *err += slew_error;
+  }
+}
+
+/* ================================================== */
+/* Positive means currently fast of true time, i.e. jump backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timespec old_time, new_time;
+  struct timeval new_time_tv;
+  double err;
+
+  LCL_ReadRawTime(&old_time);
+  UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
+  UTI_TimespecToTimeval(&new_time, &new_time_tv);
+
+  if (PRV_SetTime(&new_time_tv, NULL) < 0) {
+    DEBUG_LOG("settimeofday() failed");
+    return 0;
+  }
+
+  LCL_ReadRawTime(&old_time);
+  err = UTI_DiffTimespecsToDouble(&old_time, &new_time);
+
+  lcl_InvokeDispersionNotifyHandlers(fabs(err));
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double offset;
+
+  offset = fabs(offset_register);
+  if (est_error < offset)
+    est_error = offset;
+  max_error += offset;
+
+  if (drv_set_sync_status)
+    drv_set_sync_status(synchronised, est_error, max_error);
+}
+
+/* ================================================== */
+
+void
+SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
+                               lcl_ReadFrequencyDriver sys_read_freq,
+                               lcl_SetFrequencyDriver sys_set_freq,
+                               lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                               double min_fastslew_offset, double max_fastslew_rate,
+                               lcl_AccrueOffsetDriver sys_accrue_offset,
+                               lcl_OffsetCorrectionDriver sys_get_offset_correction,
+                               lcl_SetLeapDriver sys_set_leap,
+                               lcl_SetSyncStatusDriver sys_set_sync_status)
+{
+  max_freq = max_set_freq_ppm;
+  max_freq_change_delay = max_set_freq_delay * (1.0 + max_freq / 1.0e6);
+  drv_read_freq = sys_read_freq;
+  drv_set_freq = sys_set_freq;
+  drv_accrue_offset = sys_accrue_offset;
+  drv_get_offset_correction = sys_get_offset_correction;
+  drv_set_sync_status = sys_set_sync_status;
+
+  base_freq = (*drv_read_freq)();
+  slew_freq = 0.0;
+  offset_register = 0.0;
+  slew_excess_duration = 0.0;
+
+  max_corr_freq = CNF_GetMaxSlewRate() / 1.0e6;
+
+  fastslew_min_offset = min_fastslew_offset;
+  fastslew_max_rate = max_fastslew_rate / 1.0e6;
+  fastslew_active = 0;
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency,
+                            accrue_offset, sys_apply_step_offset ?
+                              sys_apply_step_offset : apply_step_offset,
+                            offset_convert, sys_set_leap, set_sync_status);
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Generic_Finalise(void)
+{
+  struct timespec now;
+
+  /* Must *NOT* leave a slew running - clock could drift way off
+     if the daemon is not restarted */
+
+  SCH_RemoveTimeout(slew_timeout_id);
+  slew_timeout_id = 0;
+
+  (*drv_set_freq)(clamp_freq(base_freq));
+
+  LCL_ReadRawTime(&now);
+  stop_fastslew(&now);
+
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);
+}
+
+/* ================================================== */
diff --git a/sys_generic.h b/sys_generic.h
new file mode 100644
index 0000000..d9b252e
--- /dev/null
+++ b/sys_generic.h
@@ -0,0 +1,46 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for generic driver
+  */
+
+#ifndef GOT_SYS_GENERIC_H
+#define GOT_SYS_GENERIC_H
+
+#include "localp.h"
+
+/* Register a completed driver that implements offset functions on top of
+   provided frequency functions */
+extern void SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
+                                           lcl_ReadFrequencyDriver sys_read_freq,
+                                           lcl_SetFrequencyDriver sys_set_freq,
+                                           lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                           double min_fastslew_offset, double max_fastslew_rate,
+                                           lcl_AccrueOffsetDriver sys_accrue_offset,
+                                           lcl_OffsetCorrectionDriver sys_get_offset_correction,
+                                           lcl_SetLeapDriver sys_set_leap,
+                                           lcl_SetSyncStatusDriver sys_set_sync_status);
+
+extern void SYS_Generic_Finalise(void);
+
+#endif  /* GOT_SYS_GENERIC_H */
diff --git a/sys_linux.c b/sys_linux.c
new file mode 100644
index 0000000..f2baab1
--- /dev/null
+++ b/sys_linux.c
@@ -0,0 +1,1007 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the module specific to the Linux operating system.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <sys/utsname.h>
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+#include <linux/ptp_clock.h>
+#endif
+
+#ifdef FEAT_SCFILTER
+#include <sys/prctl.h>
+#include <seccomp.h>
+#include <termios.h>
+#ifdef FEAT_PPS
+#include <linux/pps.h>
+#endif
+#ifdef FEAT_RTC
+#include <linux/rtc.h>
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include <linux/sockios.h>
+#endif
+#endif
+
+#ifdef FEAT_PRIVDROP
+#include <sys/prctl.h>
+#include <sys/capability.h>
+#endif
+
+#include "sys_linux.h"
+#include "sys_timex.h"
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "privops.h"
+#include "util.h"
+
+/* Frequency scale to convert from ppm to the timex freq */
+#define FREQ_SCALE (double)(1 << 16)
+
+/* Definitions used if missed in the system headers */
+#ifndef ADJ_SETOFFSET
+#define ADJ_SETOFFSET           0x0100  /* add 'time' to current time */
+#endif
+#ifndef ADJ_NANO
+#define ADJ_NANO                0x2000  /* select nanosecond resolution */
+#endif
+
+/* This is the uncompensated system tick value */
+static int nominal_tick;
+
+/* Current tick value */
+static int current_delta_tick;
+
+/* The maximum amount by which 'tick' can be biased away from 'nominal_tick'
+   (sys_adjtimex() in the kernel bounds this to 10%) */
+static int max_tick_bias;
+
+/* The kernel USER_HZ constant */
+static int hz;
+static double dhz; /* And dbl prec version of same for arithmetic */
+
+/* Flag indicating whether adjtimex() can step the clock */
+static int have_setoffset;
+
+/* The assumed rate at which the effective frequency and tick values are
+   updated in the kernel */
+static int tick_update_hz;
+
+/* ================================================== */
+/* Positive means currently fast of true time, i.e. jump backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timex txc;
+
+  txc.modes = ADJ_SETOFFSET | ADJ_NANO;
+  txc.time.tv_sec = -offset;
+  txc.time.tv_usec = 1.0e9 * (-offset - txc.time.tv_sec);
+  if (txc.time.tv_usec < 0) {
+    txc.time.tv_sec--;
+    txc.time.tv_usec += 1000000000;
+  }
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+/* This call sets the Linux kernel frequency to a given value in parts
+   per million relative to the nominal running frequency.  Nominal is taken to
+   be tick=10000, freq=0 (for a USER_HZ==100 system, other values otherwise).
+   The convention is that this is called with a positive argument if the local
+   clock runs fast when uncompensated.  */
+
+static double
+set_frequency(double freq_ppm)
+{
+  struct timex txc;
+  long required_tick;
+  double required_freq;
+  int required_delta_tick;
+
+  required_delta_tick = round(freq_ppm / dhz);
+
+  /* Older kernels (pre-2.6.18) don't apply the frequency offset exactly as
+     set by adjtimex() and a scaling constant (that depends on the internal
+     kernel HZ constant) would be needed to compensate for the error. Because
+     chronyd is closed loop it doesn't matter much if we don't scale the
+     required frequency, but we want to prevent thrashing between two states
+     when the system's frequency error is close to a multiple of USER_HZ.  With
+     USER_HZ <= 250, the maximum frequency adjustment of 500 ppm overlaps at
+     least two ticks and we can stick to the current tick if it's next to the
+     required tick. */
+  if (hz <= 250 && (required_delta_tick + 1 == current_delta_tick ||
+                    required_delta_tick - 1 == current_delta_tick)) {
+    required_delta_tick = current_delta_tick;
+  }
+
+  required_freq = -(freq_ppm - dhz * required_delta_tick);
+  required_tick = nominal_tick - required_delta_tick;
+
+  txc.modes = ADJ_TICK | ADJ_FREQUENCY;
+  txc.freq = required_freq * FREQ_SCALE;
+  txc.tick = required_tick;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  current_delta_tick = required_delta_tick;
+
+  return dhz * current_delta_tick - txc.freq / FREQ_SCALE;
+}
+
+/* ================================================== */
+/* Read the ppm frequency from the kernel */
+
+static double
+read_frequency(void)
+{
+  struct timex txc;
+
+  txc.modes = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  current_delta_tick = nominal_tick - txc.tick;
+
+  return dhz * current_delta_tick - txc.freq / FREQ_SCALE;
+}
+
+/* ================================================== */
+
+/* Estimate the value of USER_HZ given the value of txc.tick that chronyd finds when
+ * it starts.  The only credible values are 100 (Linux/x86) or powers of 2.
+ * Also, the bounds checking inside the kernel's adjtimex system call enforces
+ * a +/- 10% movement of tick away from the nominal value 1e6/USER_HZ. */
+
+static int
+guess_hz(void)
+{
+  struct timex txc;
+  int i, tick, tick_lo, tick_hi, ihz;
+  double tick_nominal;
+
+  txc.modes = 0;
+  SYS_Timex_Adjust(&txc, 0);
+  tick = txc.tick;
+
+  /* Pick off the hz=100 case first */
+  if (tick >= 9000 && tick <= 11000) {
+    return 100;
+  }
+
+  for (i=4; i<16; i++) { /* surely 16 .. 32768 is a wide enough range? */
+    ihz = 1 << i;
+    tick_nominal = 1.0e6 / (double) ihz;
+    tick_lo = (int)(0.5 + tick_nominal*2.0/3.0);
+    tick_hi = (int)(0.5 + tick_nominal*4.0/3.0);
+    
+    if (tick_lo < tick && tick <= tick_hi) {
+      return ihz;
+    }
+  }
+
+  /* oh dear.  doomed. */
+  LOG_FATAL("Can't determine hz from tick %d", tick);
+
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+get_hz(void)
+{
+#ifdef _SC_CLK_TCK
+  int hz;
+
+  if ((hz = sysconf(_SC_CLK_TCK)) < 1)
+    return 0;
+
+  return hz;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+kernelvercmp(int major1, int minor1, int patch1,
+    int major2, int minor2, int patch2)
+{
+  if (major1 != major2)
+    return major1 - major2;
+  if (minor1 != minor2)
+    return minor1 - minor2;
+  return patch1 - patch2;
+}
+
+/* ================================================== */
+
+static void
+get_kernel_version(int *major, int *minor, int *patch)
+{
+  struct utsname uts;
+
+  if (uname(&uts) < 0)
+    LOG_FATAL("uname() failed");
+
+  *patch = 0;
+  if (sscanf(uts.release, "%d.%d.%d", major, minor, patch) < 2)
+    LOG_FATAL("Could not parse kernel version");
+}
+
+/* ================================================== */
+
+/* Compute the scaling to use on any frequency we set, according to
+   the vintage of the Linux kernel being used. */
+
+static void
+get_version_specific_details(void)
+{
+  int major, minor, patch;
+  
+  hz = get_hz();
+
+  if (!hz)
+    hz = guess_hz();
+
+  dhz = (double) hz;
+  nominal_tick = (1000000L + (hz/2))/hz; /* Mirror declaration in kernel */
+  max_tick_bias = nominal_tick / 10;
+
+  /* In modern kernels the frequency of the clock is updated immediately in the
+     adjtimex() system call.  Assume a maximum delay of 10 microseconds. */
+  tick_update_hz = 100000;
+
+  get_kernel_version(&major, &minor, &patch);
+  DEBUG_LOG("Linux kernel major=%d minor=%d patch=%d", major, minor, patch);
+
+  if (kernelvercmp(major, minor, patch, 2, 2, 0) < 0) {
+    LOG_FATAL("Kernel version not supported, sorry.");
+  }
+
+  if (kernelvercmp(major, minor, patch, 2, 6, 27) >= 0 &&
+      kernelvercmp(major, minor, patch, 2, 6, 33) < 0) {
+    /* In tickless kernels before 2.6.33 the frequency is updated in
+       a half-second interval */
+    tick_update_hz = 2;
+  } else if (kernelvercmp(major, minor, patch, 4, 19, 0) < 0) {
+    /* In kernels before 4.19 the frequency is updated only on internal ticks
+       (CONFIG_HZ).  As their rate cannot be reliably detected from the user
+       space, and it may not even be constant (CONFIG_NO_HZ - aka tickless),
+       assume the lowest commonly used constant rate */
+    tick_update_hz = 100;
+  }
+
+  /* ADJ_SETOFFSET support */
+  if (kernelvercmp(major, minor, patch, 2, 6, 39) < 0) {
+    have_setoffset = 0;
+  } else {
+    have_setoffset = 1;
+  }
+
+  DEBUG_LOG("hz=%d nominal_tick=%d max_tick_bias=%d tick_update_hz=%d",
+            hz, nominal_tick, max_tick_bias, tick_update_hz);
+}
+
+/* ================================================== */
+
+static void
+reset_adjtime_offset(void)
+{
+  struct timex txc;
+
+  /* Reset adjtime() offset */
+  txc.modes = ADJ_OFFSET_SINGLESHOT;
+  txc.offset = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+}
+
+/* ================================================== */
+
+static int
+test_step_offset(void)
+{
+  struct timex txc;
+
+  /* Zero maxerror and check it's reset to a maximum after ADJ_SETOFFSET.
+     This seems to be the only way how to verify that the kernel really
+     supports the ADJ_SETOFFSET mode as it doesn't return an error on unknown
+     mode. */
+
+  txc.modes = MOD_MAXERROR;
+  txc.maxerror = 0;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0 || txc.maxerror != 0)
+    return 0;
+
+  txc.modes = ADJ_SETOFFSET | ADJ_NANO;
+  txc.time.tv_sec = 0;
+  txc.time.tv_usec = 0;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0 || txc.maxerror < 100000)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+report_time_adjust_blockers(void)
+{
+#if defined(FEAT_PRIVDROP) && defined(CAP_IS_SUPPORTED)
+  if (CAP_IS_SUPPORTED(CAP_SYS_TIME) && cap_get_bound(CAP_SYS_TIME))
+    return;
+  LOG(LOGS_WARN, "CAP_SYS_TIME not present");
+#endif
+}
+
+/* ================================================== */
+/* Initialisation code for this module */
+
+void
+SYS_Linux_Initialise(void)
+{
+  get_version_specific_details();
+
+  report_time_adjust_blockers();
+
+  reset_adjtime_offset();
+
+  if (have_setoffset && !test_step_offset()) {
+    LOG(LOGS_INFO, "adjtimex() doesn't support ADJ_SETOFFSET");
+    have_setoffset = 0;
+  }
+
+  SYS_Timex_InitialiseWithFunctions(1.0e6 * max_tick_bias / nominal_tick,
+                                    1.0 / tick_update_hz,
+                                    read_frequency, set_frequency,
+                                    have_setoffset ? apply_step_offset : NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+/* Finalisation code for this module */
+
+void
+SYS_Linux_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_Linux_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control)
+{
+  char cap_text[256];
+  cap_t cap;
+
+  if (prctl(PR_SET_KEEPCAPS, 1)) {
+    LOG_FATAL("prctl() failed");
+  }
+  
+  UTI_DropRoot(uid, gid);
+
+  /* Keep CAP_NET_BIND_SERVICE if the NTP server sockets may need to be bound
+     to a privileged port.
+     Keep CAP_NET_RAW if an NTP socket may need to be bound to a device on
+     kernels before 5.7.
+     Keep CAP_SYS_TIME if the clock control is enabled. */
+  if (snprintf(cap_text, sizeof (cap_text), "%s %s %s",
+               (CNF_GetNTPPort() > 0 && CNF_GetNTPPort() < 1024) ?
+                 "cap_net_bind_service=ep" : "",
+               (CNF_GetBindNtpInterface() || CNF_GetBindAcquisitionInterface()) &&
+                 !SYS_Linux_CheckKernelVersion(5, 7) ? "cap_net_raw=ep" : "",
+               clock_control ? "cap_sys_time=ep" : "") >= sizeof (cap_text))
+    assert(0);
+
+  /* Helpers don't need any capabilities */
+  if (context != SYS_MAIN_PROCESS)
+    cap_text[0] = '\0';
+
+  if ((cap = cap_from_text(cap_text)) == NULL) {
+    LOG_FATAL("cap_from_text() failed");
+  }
+
+  if (cap_set_proc(cap)) {
+    LOG_FATAL("cap_set_proc() failed");
+  }
+
+  cap_free(cap);
+}
+#endif
+
+/* ================================================== */
+
+#ifdef FEAT_SCFILTER
+static
+void check_seccomp_applicability(void)
+{
+  int mail_enabled;
+  double mail_threshold;
+  char *mail_user;
+
+  CNF_GetMailOnChange(&mail_enabled, &mail_threshold, &mail_user);
+  if (mail_enabled)
+    LOG_FATAL("mailonchange directive cannot be used with -F enabled");
+}
+
+/* ================================================== */
+
+void
+SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
+{
+  const int allowed[] = {
+    /* Clock */
+    SCMP_SYS(adjtimex),
+    SCMP_SYS(clock_adjtime),
+#ifdef __NR_clock_adjtime64
+    SCMP_SYS(clock_adjtime64),
+#endif
+    SCMP_SYS(clock_gettime),
+#ifdef __NR_clock_gettime64
+    SCMP_SYS(clock_gettime64),
+#endif
+    SCMP_SYS(gettimeofday),
+    SCMP_SYS(settimeofday),
+    SCMP_SYS(time),
+
+    /* Process */
+    SCMP_SYS(clone),
+#ifdef __NR_clone3
+    SCMP_SYS(clone3),
+#endif
+    SCMP_SYS(exit),
+    SCMP_SYS(exit_group),
+    SCMP_SYS(getpid),
+    SCMP_SYS(getrlimit),
+    SCMP_SYS(getuid),
+    SCMP_SYS(getuid32),
+#ifdef __NR_rseq
+    SCMP_SYS(rseq),
+#endif
+    SCMP_SYS(rt_sigaction),
+    SCMP_SYS(rt_sigreturn),
+    SCMP_SYS(rt_sigprocmask),
+    SCMP_SYS(set_tid_address),
+    SCMP_SYS(sigreturn),
+    SCMP_SYS(wait4),
+    SCMP_SYS(waitpid),
+
+    /* Memory */
+    SCMP_SYS(brk),
+    SCMP_SYS(madvise),
+    SCMP_SYS(mmap),
+    SCMP_SYS(mmap2),
+    SCMP_SYS(mprotect),
+    SCMP_SYS(mremap),
+    SCMP_SYS(munmap),
+    SCMP_SYS(shmdt),
+
+    /* Filesystem */
+    SCMP_SYS(_llseek),
+    SCMP_SYS(access),
+    SCMP_SYS(chmod),
+    SCMP_SYS(chown),
+    SCMP_SYS(chown32),
+    SCMP_SYS(faccessat),
+    SCMP_SYS(fchmodat),
+    SCMP_SYS(fchownat),
+    SCMP_SYS(fstat),
+    SCMP_SYS(fstat64),
+    SCMP_SYS(fstatat64),
+    SCMP_SYS(getdents),
+    SCMP_SYS(getdents64),
+    SCMP_SYS(lseek),
+    SCMP_SYS(lstat),
+    SCMP_SYS(lstat64),
+    SCMP_SYS(newfstatat),
+    SCMP_SYS(readlink),
+    SCMP_SYS(readlinkat),
+    SCMP_SYS(rename),
+    SCMP_SYS(renameat),
+#ifdef __NR_renameat2
+    SCMP_SYS(renameat2),
+#endif
+    SCMP_SYS(stat),
+    SCMP_SYS(stat64),
+    SCMP_SYS(statfs),
+    SCMP_SYS(statfs64),
+#ifdef __NR_statx
+    SCMP_SYS(statx),
+#endif
+    SCMP_SYS(unlink),
+    SCMP_SYS(unlinkat),
+
+    /* Socket */
+    SCMP_SYS(accept),
+    SCMP_SYS(bind),
+    SCMP_SYS(connect),
+    SCMP_SYS(getsockname),
+    SCMP_SYS(getsockopt),
+    SCMP_SYS(recv),
+    SCMP_SYS(recvfrom),
+    SCMP_SYS(recvmmsg),
+#ifdef __NR_recvmmsg_time64
+    SCMP_SYS(recvmmsg_time64),
+#endif
+    SCMP_SYS(recvmsg),
+    SCMP_SYS(send),
+    SCMP_SYS(sendmmsg),
+    SCMP_SYS(sendmsg),
+    SCMP_SYS(sendto),
+    SCMP_SYS(shutdown),
+    /* TODO: check socketcall arguments */
+    SCMP_SYS(socketcall),
+
+    /* General I/O */
+    SCMP_SYS(_newselect),
+    SCMP_SYS(close),
+    SCMP_SYS(open),
+    SCMP_SYS(openat),
+    SCMP_SYS(pipe),
+    SCMP_SYS(pipe2),
+    SCMP_SYS(poll),
+    SCMP_SYS(ppoll),
+#ifdef __NR_ppoll_time64
+    SCMP_SYS(ppoll_time64),
+#endif
+    SCMP_SYS(pread64),
+    SCMP_SYS(pselect6),
+#ifdef __NR_pselect6_time64
+    SCMP_SYS(pselect6_time64),
+#endif
+    SCMP_SYS(read),
+    SCMP_SYS(futex),
+#ifdef __NR_futex_time64
+    SCMP_SYS(futex_time64),
+#endif
+    SCMP_SYS(select),
+    SCMP_SYS(set_robust_list),
+    SCMP_SYS(write),
+
+    /* Miscellaneous */
+    SCMP_SYS(getrandom),
+    SCMP_SYS(sysinfo),
+    SCMP_SYS(uname),
+  };
+
+  const int denied_any[] = {
+    SCMP_SYS(execve),
+#ifdef __NR_execveat
+    SCMP_SYS(execveat),
+#endif
+    SCMP_SYS(fork),
+    SCMP_SYS(ptrace),
+    SCMP_SYS(vfork),
+  };
+
+  const int denied_ntske[] = {
+    SCMP_SYS(ioctl),
+    SCMP_SYS(setsockopt),
+    SCMP_SYS(socket),
+  };
+
+  const int socket_domains[] = {
+    AF_NETLINK, AF_UNIX, AF_INET,
+#ifdef FEAT_IPV6
+    AF_INET6,
+#endif
+  };
+
+  const static int socket_options[][2] = {
+    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND }, { SOL_IP, IP_TOS },
+#ifdef FEAT_IPV6
+    { SOL_IPV6, IPV6_V6ONLY }, { SOL_IPV6, IPV6_RECVPKTINFO },
+#endif
+#ifdef SO_BINDTODEVICE
+    { SOL_SOCKET, SO_BINDTODEVICE },
+#endif
+    { SOL_SOCKET, SO_BROADCAST }, { SOL_SOCKET, SO_REUSEADDR },
+#ifdef SO_REUSEPORT
+    { SOL_SOCKET, SO_REUSEPORT },
+#endif
+    { SOL_SOCKET, SO_TIMESTAMP }, { SOL_SOCKET, SO_TIMESTAMPNS },
+#ifdef HAVE_LINUX_TIMESTAMPING
+    { SOL_SOCKET, SO_SELECT_ERR_QUEUE }, { SOL_SOCKET, SO_TIMESTAMPING },
+#endif
+  };
+
+  const static int fcntls[] = { F_GETFD, F_SETFD, F_GETFL, F_SETFL };
+
+  const static unsigned long ioctls[] = {
+    FIONREAD, TCGETS,
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+    PTP_EXTTS_REQUEST, PTP_SYS_OFFSET,
+#ifdef PTP_PIN_SETFUNC
+    PTP_PIN_SETFUNC,
+#endif
+#ifdef PTP_SYS_OFFSET_EXTENDED
+    PTP_SYS_OFFSET_EXTENDED,
+#endif
+#ifdef PTP_SYS_OFFSET_PRECISE
+    PTP_SYS_OFFSET_PRECISE,
+#endif
+#endif
+#ifdef FEAT_PPS
+    PPS_FETCH,
+#endif
+#ifdef FEAT_RTC
+    RTC_RD_TIME, RTC_SET_TIME, RTC_UIE_ON, RTC_UIE_OFF,
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+    SIOCETHTOOL,
+#endif
+  };
+
+  unsigned int default_action, deny_action;
+  scmp_filter_ctx *ctx;
+  int i;
+
+  /* Sign of the level determines the deny action (kill or SIGSYS).
+     At level 1, selected syscalls are allowed, others are denied.
+     At level 2, selected syscalls are denied, others are allowed. */
+
+  deny_action = level > 0 ? SCMP_ACT_KILL : SCMP_ACT_TRAP;
+  if (level < 0)
+    level = -level;
+
+  switch (level) {
+    case 1:
+      default_action = deny_action;
+      break;
+    case 2:
+      default_action = SCMP_ACT_ALLOW;
+      break;
+    default:
+      LOG_FATAL("Unsupported filter level");
+  }
+
+  if (context == SYS_MAIN_PROCESS) {
+    /* Check if the chronyd configuration is supported */
+    check_seccomp_applicability();
+
+    /* At level 1, start a helper process which will not have a seccomp filter.
+       It will be used for getaddrinfo(), for which it is difficult to maintain
+       a list of required system calls (with glibc it depends on what NSS
+       modules are installed and enabled on the system). */
+    if (default_action != SCMP_ACT_ALLOW)
+      PRV_StartHelper();
+  }
+
+  ctx = seccomp_init(default_action);
+  if (ctx == NULL)
+      LOG_FATAL("Failed to initialize seccomp");
+
+  if (default_action != SCMP_ACT_ALLOW) {
+    for (i = 0; i < sizeof (allowed) / sizeof (*allowed); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, allowed[i], 0) < 0)
+        goto add_failed;
+    }
+  } else {
+    for (i = 0; i < sizeof (denied_any) / sizeof (*denied_any); i++) {
+      if (seccomp_rule_add(ctx, deny_action, denied_any[i], 0) < 0)
+        goto add_failed;
+    }
+
+    if (context == SYS_NTSKE_HELPER) {
+      for (i = 0; i < sizeof (denied_ntske) / sizeof (*denied_ntske); i++) {
+        if (seccomp_rule_add(ctx, deny_action, denied_ntske[i], 0) < 0)
+          goto add_failed;
+      }
+    }
+  }
+
+  if (default_action != SCMP_ACT_ALLOW && context == SYS_MAIN_PROCESS) {
+    /* Allow opening sockets in selected domains */
+    for (i = 0; i < sizeof (socket_domains) / sizeof (*socket_domains); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
+                           SCMP_A0(SCMP_CMP_EQ, socket_domains[i])) < 0)
+        goto add_failed;
+    }
+
+    /* Allow selected socket options */
+    for (i = 0; i < sizeof (socket_options) / sizeof (*socket_options); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), 2,
+                           SCMP_A1(SCMP_CMP_EQ, socket_options[i][0]),
+                           SCMP_A2(SCMP_CMP_EQ, socket_options[i][1])))
+        goto add_failed;
+    }
+
+    /* Allow selected fcntl calls */
+    for (i = 0; i < sizeof (fcntls) / sizeof (*fcntls); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl), 1,
+                           SCMP_A1(SCMP_CMP_EQ, fcntls[i])) < 0 ||
+          seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), 1,
+                           SCMP_A1(SCMP_CMP_EQ, fcntls[i])) < 0)
+        goto add_failed;
+    }
+
+    /* Allow selected ioctls */
+    for (i = 0; i < sizeof (ioctls) / sizeof (*ioctls); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(ioctl), 1,
+                           SCMP_A1(SCMP_CMP_EQ, ioctls[i])) < 0)
+        goto add_failed;
+    }
+  }
+
+  if (seccomp_load(ctx) < 0)
+    LOG_FATAL("Failed to load seccomp rules");
+
+  LOG(context == SYS_MAIN_PROCESS ? LOGS_INFO : LOGS_DEBUG,
+      "Loaded seccomp filter (level %d)", level);
+  seccomp_release(ctx);
+  return;
+
+add_failed:
+  LOG_FATAL("Failed to add seccomp rules");
+}
+#endif
+
+/* ================================================== */
+
+int
+SYS_Linux_CheckKernelVersion(int req_major, int req_minor)
+{
+  int major, minor, patch;
+
+  get_kernel_version(&major, &minor, &patch);
+
+  return kernelvercmp(req_major, req_minor, 0, major, minor, patch) <= 0;
+}
+
+/* ================================================== */
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+
+static int
+get_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+  struct ptp_sys_offset sys_off;
+  int i;
+
+  max_samples = CLAMP(0, max_samples, PTP_MAX_SAMPLES);
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  sys_off.n_samples = max_samples;
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET", strerror(errno));
+    return 0;
+  }
+
+  for (i = 0; i < max_samples; i++) {
+    ts[i][0].tv_sec = sys_off.ts[i * 2].sec;
+    ts[i][0].tv_nsec = sys_off.ts[i * 2].nsec;
+    ts[i][1].tv_sec = sys_off.ts[i * 2 + 1].sec;
+    ts[i][1].tv_nsec = sys_off.ts[i * 2 + 1].nsec;
+    ts[i][2].tv_sec = sys_off.ts[i * 2 + 2].sec;
+    ts[i][2].tv_nsec = sys_off.ts[i * 2 + 2].nsec;
+  }
+
+  return max_samples;
+}
+
+/* ================================================== */
+
+static int
+get_extended_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+#ifdef PTP_SYS_OFFSET_EXTENDED
+  struct ptp_sys_offset_extended sys_off;
+  int i;
+
+  max_samples = CLAMP(0, max_samples, PTP_MAX_SAMPLES);
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  sys_off.n_samples = max_samples;
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET_EXTENDED, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET_EXTENDED", strerror(errno));
+    return 0;
+  }
+
+  for (i = 0; i < max_samples; i++) {
+    ts[i][0].tv_sec = sys_off.ts[i][0].sec;
+    ts[i][0].tv_nsec = sys_off.ts[i][0].nsec;
+    ts[i][1].tv_sec = sys_off.ts[i][1].sec;
+    ts[i][1].tv_nsec = sys_off.ts[i][1].nsec;
+    ts[i][2].tv_sec = sys_off.ts[i][2].sec;
+    ts[i][2].tv_nsec = sys_off.ts[i][2].nsec;
+  }
+
+  return max_samples;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+get_precise_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+#ifdef PTP_SYS_OFFSET_PRECISE
+  struct ptp_sys_offset_precise sys_off;
+
+  if (max_samples < 1)
+    return 0;
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET_PRECISE, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET_PRECISE",
+              strerror(errno));
+    return 0;
+  }
+
+  ts[0][0].tv_sec = sys_off.sys_realtime.sec;
+  ts[0][0].tv_nsec = sys_off.sys_realtime.nsec;
+  ts[0][1].tv_sec = sys_off.device.sec;
+  ts[0][1].tv_nsec = sys_off.device.nsec;
+  ts[0][2] = ts[0][0];
+
+  return 1;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_OpenPHC(const char *path, int phc_index)
+{
+  struct ptp_clock_caps caps;
+  char phc_path[64];
+  int phc_fd;
+
+  if (!path) {
+    if (snprintf(phc_path, sizeof (phc_path), "/dev/ptp%d", phc_index) >= sizeof (phc_path))
+      return -1;
+    path = phc_path;
+  }
+
+  phc_fd = open(path, O_RDONLY);
+  if (phc_fd < 0) {
+    LOG(LOGS_ERR, "Could not open %s : %s", path, strerror(errno));
+    return -1;
+  }
+
+  /* Make sure it is a PHC */
+  if (ioctl(phc_fd, PTP_CLOCK_GETCAPS, &caps)) {
+    LOG(LOGS_ERR, "ioctl(%s) failed : %s", "PTP_CLOCK_GETCAPS", strerror(errno));
+    close(phc_fd);
+    return -1;
+  }
+
+  UTI_FdSetCloexec(phc_fd);
+
+  return phc_fd;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_GetPHCReadings(int fd, int nocrossts, int *reading_mode, int max_readings,
+                         struct timespec tss[][3])
+{
+  int r = 0;
+
+  if ((*reading_mode == 2 || *reading_mode == 0) && !nocrossts &&
+      (r = get_precise_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 2;
+  } else if ((*reading_mode == 3 || *reading_mode == 0) &&
+             (r = get_extended_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 3;
+  } else if ((*reading_mode == 1 || *reading_mode == 0) &&
+             (r = get_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 1;
+  }
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_SetPHCExtTimestamping(int fd, int pin, int channel,
+                                int rising, int falling, int enable)
+{
+  struct ptp_extts_request extts_req;
+#ifdef PTP_PIN_SETFUNC
+  struct ptp_pin_desc pin_desc;
+
+  memset(&pin_desc, 0, sizeof (pin_desc));
+  pin_desc.index = pin;
+  pin_desc.func = enable ? PTP_PF_EXTTS : PTP_PF_NONE;
+  pin_desc.chan = channel;
+
+  if (pin >= 0 && ioctl(fd, PTP_PIN_SETFUNC, &pin_desc)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_PIN_SETFUNC", strerror(errno));
+    return 0;
+  }
+#else
+  DEBUG_LOG("Missing PTP_PIN_SETFUNC");
+  return 0;
+#endif
+
+  memset(&extts_req, 0, sizeof (extts_req));
+  extts_req.index = channel;
+  extts_req.flags = (enable ? PTP_ENABLE_FEATURE : 0) |
+                    (rising ? PTP_RISING_EDGE : 0) |
+                    (falling ? PTP_FALLING_EDGE : 0);
+
+  if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_EXTTS_REQUEST", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_ReadPHCExtTimestamp(int fd, struct timespec *phc_ts, int *channel)
+{
+  struct ptp_extts_event extts_event;
+
+  if (read(fd, &extts_event, sizeof (extts_event)) != sizeof (extts_event)) {
+    DEBUG_LOG("Could not read PHC extts event");
+    return 0;
+  }
+
+  phc_ts->tv_sec = extts_event.t.sec;
+  phc_ts->tv_nsec = extts_event.t.nsec;
+  *channel = extts_event.index;
+
+  return 1;
+}
+
+#endif
diff --git a/sys_linux.h b/sys_linux.h
new file mode 100644
index 0000000..4741624
--- /dev/null
+++ b/sys_linux.h
@@ -0,0 +1,52 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The header file for the linux driver
+  */
+
+#ifndef GOT_SYS_LINUX_H
+#define GOT_SYS_LINUX_H
+
+#include "sys.h"
+
+extern void SYS_Linux_Initialise(void);
+
+extern void SYS_Linux_Finalise(void);
+
+extern void SYS_Linux_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control);
+
+extern void SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context);
+
+extern int SYS_Linux_CheckKernelVersion(int req_major, int req_minor);
+
+extern int SYS_Linux_OpenPHC(const char *path, int phc_index);
+
+extern int SYS_Linux_GetPHCReadings(int fd, int nocrossts, int *reading_mode, int max_readings,
+                                    struct timespec tss[][3]);
+
+extern int SYS_Linux_SetPHCExtTimestamping(int fd, int pin, int channel,
+                                           int rising, int falling, int enable);
+
+extern int SYS_Linux_ReadPHCExtTimestamp(int fd, struct timespec *phc_ts, int *channel);
+
+#endif  /* GOT_SYS_LINUX_H */
diff --git a/sys_macosx.c b/sys_macosx.c
new file mode 100644
index 0000000..e3a38ed
--- /dev/null
+++ b/sys_macosx.c
@@ -0,0 +1,516 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Bryan Christianson  2015, 2017, 2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for the macOS operating system.
+
+  */
+
+#include "config.h"
+
+#ifdef MACOSX
+
+#include "sysincl.h"
+
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <pthread.h>
+
+#include "sys_macosx.h"
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "sched.h"
+#include "privops.h"
+#include "util.h"
+
+#include <dlfcn.h>
+
+#ifdef HAVE_MACOS_SYS_TIMEX
+#include "sys_netbsd.h"
+
+static int have_ntp_adjtime = 0;
+#endif
+
+/* ================================================== */
+
+/* This register contains the number of seconds by which the local
+   clock was estimated to be fast of reference time at the epoch when
+   LCL_ReadRawTime() returned T0 */
+
+static double offset_register;
+
+/* This register contains the epoch to which the offset is referenced */
+
+static struct timespec T0;
+
+/* This register contains the current estimate of the system
+   frequency, in absolute (NOT ppm) */
+
+static double current_freq;
+
+/* This register contains the number of seconds of adjustment that
+   were passed to adjtime last time it was called. */
+
+static double adjustment_requested;
+
+/* Interval in seconds between adjustments to cancel systematic drift */
+
+#define DRIFT_REMOVAL_INTERVAL (4.0)
+#define DRIFT_REMOVAL_INTERVAL_MIN (0.5)
+
+/* If current_drift_removal_interval / drift_removal_interval exceeds this
+   ratio, then restart the drift removal timer */
+
+#define DRIFT_REMOVAL_RESTART_RATIO (8.0)
+
+static double drift_removal_interval;
+static double current_drift_removal_interval;
+static struct timespec Tdrift;
+
+/* weighting applied to error in calculating drift_removal_interval */
+#define ERROR_WEIGHT (0.5)
+
+/* minimum resolution of current_frequency */
+#define FREQUENCY_RES (1.0e-9)
+
+#define NANOS_PER_MSEC (1000000ULL)
+
+/* RTC synchronisation - once an hour */
+
+static struct timespec last_rtc_sync;
+#define RTC_SYNC_INTERVAL (60 * 60.0)
+
+/* ================================================== */
+
+static void
+clock_initialise(void)
+{
+  struct timeval newadj, oldadj;
+
+  offset_register = 0.0;
+  adjustment_requested = 0.0;
+  current_freq = 0.0;
+  drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+  current_drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+
+  LCL_ReadRawTime(&T0);
+  Tdrift = T0;
+  last_rtc_sync = T0;
+
+  newadj.tv_sec = 0;
+  newadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+}
+
+/* ================================================== */
+
+static void
+clock_finalise(void)
+{
+  /* Nothing to do yet */
+}
+
+/* ================================================== */
+
+static void
+start_adjust(void)
+{
+  struct timeval newadj, oldadj;
+  struct timespec T1;
+  double elapsed, accrued_error, predicted_error, drift_removal_elapsed;
+  double adjust_required;
+  double rounding_error;
+  double old_adjust_remaining;
+
+  /* Determine the amount of error built up since the last adjustment */
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  accrued_error = elapsed * current_freq;
+
+  drift_removal_elapsed = UTI_DiffTimespecsToDouble(&T1, &Tdrift);
+
+  /* To allow for the clock being stepped either forward or backwards, clamp
+     the elapsed time to bounds [ 0.0, current_drift_removal_interval ] */
+  drift_removal_elapsed = MIN(MAX(0.0, drift_removal_elapsed), current_drift_removal_interval);
+
+  predicted_error = (current_drift_removal_interval - drift_removal_elapsed) / 2.0 * current_freq;
+
+  DEBUG_LOG("drift_removal_elapsed: %.3f current_drift_removal_interval: %.3f predicted_error: %.3f",
+            1.0e6 * drift_removal_elapsed, 1.0e6 * current_drift_removal_interval,
+            1.0e6 * predicted_error);
+
+  adjust_required = - (accrued_error + offset_register + predicted_error);
+
+  UTI_DoubleToTimeval(adjust_required, &newadj);
+  adjustment_requested = UTI_TimevalToDouble(&newadj);
+  rounding_error = adjust_required - adjustment_requested;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  old_adjust_remaining = UTI_TimevalToDouble(&oldadj);
+
+  offset_register = rounding_error - old_adjust_remaining - predicted_error;
+
+  T0 = T1;
+}
+
+/* ================================================== */
+
+static void
+stop_adjust(void)
+{
+  struct timespec T1;
+  struct timeval zeroadj, remadj;
+  double adjustment_remaining, adjustment_achieved;
+  double elapsed, elapsed_plus_adjust;
+
+  zeroadj.tv_sec = 0;
+  zeroadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&zeroadj, &remadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  adjustment_remaining = UTI_TimevalToDouble(&remadj);
+
+  adjustment_achieved = adjustment_requested - adjustment_remaining;
+  elapsed_plus_adjust = elapsed - adjustment_achieved;
+
+  offset_register += current_freq * elapsed_plus_adjust - adjustment_remaining;
+
+  adjustment_requested = 0.0;
+  T0 = T1;
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   slew backwards */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  stop_adjust();
+  offset_register += offset;
+  start_adjust();
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   step backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timespec old_time, new_time, T1;
+  struct timeval new_time_tv;
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&old_time);
+
+  UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
+  UTI_TimespecToTimeval(&new_time, &new_time_tv);
+
+  if (PRV_SetTime(&new_time_tv, NULL) < 0) {
+    DEBUG_LOG("settimeofday() failed");
+    return 0;
+  }
+
+  UTI_AddDoubleToTimespec(&T0, -offset, &T1);
+  T0 = T1;
+
+  start_adjust();
+
+  return 1;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double new_freq_ppm)
+{
+  stop_adjust();
+  current_freq = new_freq_ppm * 1.0e-6;
+  start_adjust();
+
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static void
+get_offset_correction(struct timespec *raw,
+                      double *corr, double *err)
+{
+  stop_adjust();
+  *corr = -offset_register;
+  start_adjust();
+  if (err)
+    *err = 0.0;
+}
+
+/* ================================================== */
+
+/* Cancel systematic drift */
+
+static SCH_TimeoutID drift_removal_id;
+
+/* ================================================== */
+/* This is the timer callback routine which is called periodically to
+ invoke a time adjustment to take out the machine's drift.
+ Otherwise, times reported through this software (e.g. by running
+ ntpdate from another machine) show the machine being correct (since
+ they correct for drift build-up), but any program on this machine
+ that reads the system time will be given an erroneous value, the
+ degree of error depending on how long it is since
+ get_offset_correction was last called. */
+
+static void
+drift_removal_timeout(SCH_ArbitraryArgument not_used)
+{
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&Tdrift);
+
+  current_drift_removal_interval = drift_removal_interval;
+
+  start_adjust();
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+/* use est_error to calculate the drift_removal_interval and
+   update the RTC */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double interval;
+
+  if (!synchronised) {
+    drift_removal_interval = MAX(drift_removal_interval, DRIFT_REMOVAL_INTERVAL);
+  } else {
+    if (CNF_GetRtcSync()) {
+      struct timespec now;
+      double rtc_sync_elapsed;
+
+      SCH_GetLastEventTime(NULL, NULL, &now);
+      rtc_sync_elapsed = UTI_DiffTimespecsToDouble(&now, &last_rtc_sync);
+      if (fabs(rtc_sync_elapsed) >= RTC_SYNC_INTERVAL) {
+        /* update the RTC by applying a step of 0.0 secs */
+        apply_step_offset(0.0);
+        last_rtc_sync = now;
+        DEBUG_LOG("rtc synchronised");
+      }
+    }
+
+    interval = ERROR_WEIGHT * est_error / (fabs(current_freq) + FREQUENCY_RES);
+    drift_removal_interval = MAX(interval, DRIFT_REMOVAL_INTERVAL_MIN);
+
+    DEBUG_LOG("est_error: %.3f current_freq: %.3f est drift_removal_interval: %.3f act drift_removal_interval: %.3f",
+                est_error * 1.0e6, current_freq * 1.0e6, interval, drift_removal_interval);
+  }
+
+  if (current_drift_removal_interval / drift_removal_interval > DRIFT_REMOVAL_RESTART_RATIO) {
+    /* recover from a large est_error by resetting the timer */
+    SCH_ArbitraryArgument unused;
+    SCH_RemoveTimeout(drift_removal_id);
+    unused = NULL;
+    drift_removal_timeout(unused);
+  }
+}
+
+/* ================================================== */
+/*
+  Give chronyd real time priority so that time critical calculations
+  are not pre-empted by the kernel.
+*/
+
+static int
+set_realtime(void)
+{
+  /* https://developer.apple.com/library/ios/technotes/tn2169/_index.html */
+
+  mach_timebase_info_data_t timebase_info;
+  double clock2abs;
+  thread_time_constraint_policy_data_t policy;
+  int kr;
+
+  mach_timebase_info(&timebase_info);
+  clock2abs = ((double)timebase_info.denom / (double)timebase_info.numer) * NANOS_PER_MSEC;
+
+  policy.period = 0;
+  policy.computation = (uint32_t)(5 * clock2abs); /* 5 ms of work */
+  policy.constraint = (uint32_t)(10 * clock2abs);
+  policy.preemptible = 0;
+
+  kr = thread_policy_set(
+          pthread_mach_thread_np(pthread_self()),
+          THREAD_TIME_CONSTRAINT_POLICY,
+          (thread_policy_t)&policy,
+          THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+
+  if (kr != KERN_SUCCESS) {
+    LOG(LOGS_WARN, "Cannot set real-time priority: %d", kr);
+    return -1;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_SetScheduler(int SchedPriority)
+{
+  if (SchedPriority) {
+    set_realtime();
+  }
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void SYS_MacOSX_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+
+  UTI_DropRoot(uid, gid);
+}
+#endif
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Initialise(void)
+{
+  clock_initialise();
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency,
+                            accrue_offset, apply_step_offset,
+                            get_offset_correction,
+                            NULL /* set_leap */,
+                            set_sync_status);
+
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Finalise(void)
+{
+  SCH_RemoveTimeout(drift_removal_id);
+
+  clock_finalise();
+}
+
+/* ================================================== */
+
+#if HAVE_CLOCK_GETTIME
+int
+clock_gettime(clockid_t clock_id, struct timespec *ts)
+{
+  /* Check that the system clock_gettime symbol is actually present before
+     attempting to call it. The symbol is available in macOS 10.12
+     and later. */
+
+  static int init = 0;
+  static int (*sys_clock_gettime)(clockid_t, struct timespec *) = NULL;
+  int ret = 0;
+
+  if (!init) {
+    sys_clock_gettime = dlsym(RTLD_NEXT, "clock_gettime");
+    init = 1;
+  }
+
+  if (sys_clock_gettime != NULL) {
+    ret = sys_clock_gettime(clock_id, ts);
+  } else {
+    struct timeval tv;
+
+    if (gettimeofday(&tv, NULL) < 0)
+      LOG_FATAL("gettimeofday() failed : %s", strerror(errno));
+
+    UTI_TimevalToTimespec(&tv, ts);
+  }
+  return ret;
+}
+#endif
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Initialise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  have_ntp_adjtime = (dlsym(RTLD_NEXT, "ntp_adjtime") != NULL);
+  if (have_ntp_adjtime) {
+    SYS_NetBSD_Initialise();
+    return;
+  }
+#endif
+  legacy_MacOSX_Initialise();
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Finalise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  if (have_ntp_adjtime) {
+    SYS_NetBSD_Finalise();
+    return;
+  }
+#endif
+  legacy_MacOSX_Finalise();
+}
+
+#endif
diff --git a/sys_macosx.h b/sys_macosx.h
new file mode 100644
index 0000000..09f0beb
--- /dev/null
+++ b/sys_macosx.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Bryan Christianson 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for macOS driver
+
+  */
+
+#ifndef GOT_SYS_MACOSX_H
+#define GOT_SYS_MACOSX_H
+
+#include "sys.h"
+
+void SYS_MacOSX_SetScheduler(int SchedPriority);
+void SYS_MacOSX_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+void SYS_MacOSX_Initialise(void);
+void SYS_MacOSX_Finalise(void);
+
+#endif
diff --git a/sys_netbsd.c b/sys_netbsd.c
new file mode 100644
index 0000000..e1b99bb
--- /dev/null
+++ b/sys_netbsd.c
@@ -0,0 +1,158 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for the NetBSD and FreeBSD operating system.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_netbsd.h"
+#include "sys_timex.h"
+#include "logging.h"
+#include "privops.h"
+#include "util.h"
+
+/* Maximum frequency offset accepted by the kernel (in ppm) */
+#define MAX_FREQ 500.0
+
+/* Minimum assumed rate at which the kernel updates the clock frequency */
+#define MIN_TICK_RATE 100
+
+/* Interval between kernel updates of the adjtime() offset */
+#define ADJTIME_UPDATE_INTERVAL 1.0
+
+/* Maximum adjtime() slew rate (in ppm) */
+#define MAX_ADJTIME_SLEWRATE 5000.0
+
+/* Minimum offset adjtime() slews faster than MAX_FREQ */
+#define MIN_FASTSLEW_OFFSET 1.0
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   slew backwards */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  struct timeval newadj, oldadj;
+  double doldadj;
+
+  UTI_DoubleToTimeval(-offset, &newadj);
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0)
+    LOG_FATAL("adjtime() failed");
+
+  /* Add the old remaining adjustment if not zero */
+  doldadj = UTI_TimevalToDouble(&oldadj);
+  if (doldadj != 0.0) {
+    UTI_DoubleToTimeval(-offset + doldadj, &newadj);
+    if (PRV_AdjustTime(&newadj, NULL) < 0)
+      LOG_FATAL("adjtime() failed");
+  }
+}
+
+/* ================================================== */
+
+static void
+get_offset_correction(struct timespec *raw,
+                      double *corr, double *err)
+{
+  struct timeval remadj;
+  double adjustment_remaining;
+#ifdef MACOSX
+  struct timeval tv = {0, 0};
+
+  if (PRV_AdjustTime(&tv, &remadj) < 0)
+    LOG_FATAL("adjtime() failed");
+
+  if (PRV_AdjustTime(&remadj, NULL) < 0)
+    LOG_FATAL("adjtime() failed");
+#else
+  if (PRV_AdjustTime(NULL, &remadj) < 0)
+    LOG_FATAL("adjtime() failed");
+#endif
+
+  adjustment_remaining = UTI_TimevalToDouble(&remadj);
+
+  *corr = adjustment_remaining;
+  if (err) {
+    if (*corr != 0.0)
+      *err = 1.0e-6 * MAX_ADJTIME_SLEWRATE / ADJTIME_UPDATE_INTERVAL;
+    else
+      *err = 0.0;
+  }
+}
+
+/* ================================================== */
+
+void
+SYS_NetBSD_Initialise(void)
+{
+  SYS_Timex_InitialiseWithFunctions(MAX_FREQ, 1.0 / MIN_TICK_RATE,
+                                    NULL, NULL, NULL,
+                                    MIN_FASTSLEW_OFFSET, MAX_ADJTIME_SLEWRATE,
+                                    accrue_offset, get_offset_correction);
+}
+
+/* ================================================== */
+
+void
+SYS_NetBSD_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_NetBSD_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control)
+{
+#ifdef NETBSD
+  int fd;
+#endif
+
+  /* On NetBSD the helper is used only for socket binding, but on FreeBSD
+     it's used also for setting and adjusting the system clock */
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+
+  UTI_DropRoot(uid, gid);
+
+#ifdef NETBSD
+  if (!clock_control)
+    return;
+
+  /* Check if we have write access to /dev/clockctl */
+  fd = open("/dev/clockctl", O_WRONLY);
+  if (fd < 0)
+    LOG_FATAL("Can't write to /dev/clockctl");
+  close(fd);
+#endif
+}
+#endif
diff --git a/sys_netbsd.h b/sys_netbsd.h
new file mode 100644
index 0000000..7a05e6c
--- /dev/null
+++ b/sys_netbsd.h
@@ -0,0 +1,39 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NetBSD driver
+  */
+
+#ifndef GOT_SYS_NETBSD_H
+#define GOT_SYS_NETBSD_H
+
+#include "sys.h"
+
+void SYS_NetBSD_Initialise(void);
+
+void SYS_NetBSD_Finalise(void);
+
+void SYS_NetBSD_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control);
+
+#endif
diff --git a/sys_null.c b/sys_null.c
new file mode 100644
index 0000000..3a0d5f6
--- /dev/null
+++ b/sys_null.c
@@ -0,0 +1,140 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Null clock driver for operation with no clock control.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_null.h"
+
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "util.h"
+
+/* Current frequency offset of the system clock (in ppm) */
+static double freq;
+
+/* Offset of the system clock at the last update */
+static double offset_register;
+
+/* Time of the last update */
+static struct timespec last_update;
+
+/* Minimum interval between updates when frequency is constant */
+#define MIN_UPDATE_INTERVAL 1000.0
+
+/* ================================================== */
+
+static void
+update_offset(void)
+{
+  struct timespec now;
+  double duration;
+
+  LCL_ReadRawTime(&now);
+  duration = UTI_DiffTimespecsToDouble(&now, &last_update);
+  offset_register += 1.0e-6 * freq * duration;
+  last_update = now;
+
+  DEBUG_LOG("System clock offset=%e freq=%f", offset_register, freq);
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return freq;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  update_offset();
+  freq = freq_ppm;
+
+  return freq;
+}
+
+/* ================================================== */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  offset_register += offset;
+}
+
+/* ================================================== */
+
+static int
+apply_step_offset(double offset)
+{
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+offset_convert(struct timespec *raw, double *corr, double *err)
+{
+  double duration;
+
+  duration = UTI_DiffTimespecsToDouble(raw, &last_update);
+
+  if (duration > MIN_UPDATE_INTERVAL) {
+    update_offset();
+    duration = 0.0;
+  }
+
+  *corr = -1.0e-6 * freq * duration - offset_register;
+
+  if (err)
+    *err = 0.0;
+}
+
+/* ================================================== */
+
+void
+SYS_Null_Initialise(void)
+{
+  offset_register = 0.0;
+  LCL_ReadRawTime(&last_update);
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency, accrue_offset,
+                            apply_step_offset, offset_convert, NULL, NULL);
+
+  LOG(LOGS_INFO, "Disabled control of system clock");
+}
+
+/* ================================================== */
+
+void
+SYS_Null_Finalise(void)
+{
+}
diff --git a/sys_null.h b/sys_null.h
new file mode 100644
index 0000000..0fbf077
--- /dev/null
+++ b/sys_null.h
@@ -0,0 +1,34 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for null clock driver
+  */
+
+#ifndef GOT_SYS_NULL_H
+#define GOT_SYS_NULL_H
+
+extern void SYS_Null_Initialise(void);
+
+extern void SYS_Null_Finalise(void);
+
+#endif
diff --git a/sys_posix.c b/sys_posix.c
new file mode 100644
index 0000000..356e86a
--- /dev/null
+++ b/sys_posix.c
@@ -0,0 +1,109 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  This module is for POSIX compliant operating systems.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <sys/utsname.h>
+
+#if defined(HAVE_PTHREAD_SETSCHEDPARAM)
+#include <pthread.h>
+#include <sched.h>
+#endif
+
+#if defined(HAVE_MLOCKALL)
+#include <sys/mman.h>
+#endif
+#if defined(HAVE_SETRLIMIT_MEMLOCK)
+#include <sys/resource.h>
+#endif
+
+#include "sys_posix.h"
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "util.h"
+
+/* ================================================== */
+
+#if defined(HAVE_PTHREAD_SETSCHEDPARAM)
+/* Install SCHED_FIFO real-time scheduler with specified priority */
+void
+SYS_Posix_SetScheduler(int priority)
+{
+  struct sched_param sched;
+  int pmax, pmin;
+
+  if (priority < 1 || priority > 99)
+    LOG_FATAL("Bad scheduler priority: %d", priority);
+
+  sched.sched_priority = priority;
+  pmax = sched_get_priority_max(SCHED_FIFO);
+  pmin = sched_get_priority_min(SCHED_FIFO);
+  if (priority > pmax) {
+    sched.sched_priority = pmax;
+  } else if (priority < pmin) {
+    sched.sched_priority = pmin;
+  }
+
+  if (pthread_setschedparam(pthread_self(), SCHED_FIFO, &sched) < 0) {
+    LOG(LOGS_ERR, "pthread_setschedparam() failed");
+  } else {
+    DEBUG_LOG("Enabled SCHED_FIFO with priority %d", sched.sched_priority);
+  }
+}
+#endif /* HAVE_PTHREAD_SETSCHEDPARAM  */
+
+/* ================================================== */
+
+#if defined(HAVE_MLOCKALL)
+/* Lock the process into RAM so that it will never be swapped out */
+void
+SYS_Posix_MemLockAll(void)
+{
+#if defined(HAVE_SETRLIMIT_MEMLOCK)
+  struct rlimit rlim;
+
+  /* Ensure we can reserve as much as we need */
+  rlim.rlim_max = RLIM_INFINITY;
+  rlim.rlim_cur = RLIM_INFINITY;
+  if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
+    LOG(LOGS_ERR, "setrlimit() failed");
+    return;
+  }
+#endif
+
+  if (mlockall(MCL_CURRENT|MCL_FUTURE) < 0) {
+    LOG(LOGS_ERR, "mlockall() failed");
+  } else {
+    DEBUG_LOG("Successfully locked into RAM");
+  }
+}
+#endif /* HAVE_MLOCKALL */
diff --git a/sys_posix.h b/sys_posix.h
new file mode 100644
index 0000000..bb34b80
--- /dev/null
+++ b/sys_posix.h
@@ -0,0 +1,36 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  The header file for shared Posix functionality
+  */
+
+#ifndef GOT_SYS_POSIX_H
+#define GOT_SYS_POSIX_H
+
+extern void SYS_Posix_MemLockAll(void);
+
+extern void SYS_Posix_SetScheduler(int priority);
+
+#endif  /* GOT_SYS_POSIX_H */
diff --git a/sys_solaris.c b/sys_solaris.c
new file mode 100644
index 0000000..3210ef0
--- /dev/null
+++ b/sys_solaris.c
@@ -0,0 +1,95 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for illumos operating system (previously Solaris)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "logging.h"
+#include "privops.h"
+#include "sys_solaris.h"
+#include "sys_timex.h"
+#include "util.h"
+
+#include <kvm.h>
+#include <nlist.h>
+
+/* ================================================== */
+
+static void
+set_dosynctodr(int on_off)
+{
+  struct nlist nl[] = { {"dosynctodr"}, {NULL} };
+  kvm_t *kt;
+
+  kt = kvm_open(NULL, NULL, NULL, O_RDWR, NULL);
+  if (!kt)
+    LOG_FATAL("Could not open kvm");
+
+  if (kvm_nlist(kt, nl) < 0 || !nl[0].n_value)
+    LOG_FATAL("Could not get dosynctodr address");
+
+  if (kvm_kwrite(kt, nl[0].n_value, &on_off, sizeof (on_off)) < 0)
+    LOG_FATAL("Could not write to dosynctodr");
+
+  kvm_close(kt);
+}
+
+/* ================================================== */
+
+void
+SYS_Solaris_Initialise(void)
+{
+  /* The kernel keeps the system clock and hardware clock synchronised to each
+     other.  The dosynctodr variable needs to be set to zero to prevent the
+     the system clock from following the hardware clock when the system clock
+     is not adjusted by adjtime() or ntp_adjtime(modes=MOD_OFFSET). */
+  set_dosynctodr(0);
+
+  /* The kernel allows the frequency to be set in the full range off int32_t */
+  SYS_Timex_InitialiseWithFunctions(32500, 1.0 / 100, NULL, NULL, NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Solaris_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_Solaris_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+  UTI_DropRoot(uid, gid);
+}
+#endif
diff --git a/sys_solaris.h b/sys_solaris.h
new file mode 100644
index 0000000..5979232
--- /dev/null
+++ b/sys_solaris.h
@@ -0,0 +1,38 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for Solaris driver
+  */
+
+#ifndef GOT_SYS_SOLARIS_H
+#define GOT_SYS_SOLARIS_H
+
+#include "sys.h"
+
+void SYS_Solaris_Initialise(void);
+
+void SYS_Solaris_Finalise(void);
+
+void SYS_Solaris_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+
+#endif
diff --git a/sys_timex.c b/sys_timex.c
new file mode 100644
index 0000000..0ee6c8e
--- /dev/null
+++ b/sys_timex.c
@@ -0,0 +1,276 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2015, 2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver for systems that implement the adjtimex()/ntp_adjtime() system call
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "privops.h"
+#include "sys_generic.h"
+#include "sys_timex.h"
+#include "logging.h"
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+#define NTP_ADJTIME PRV_AdjustTimex
+#define NTP_ADJTIME_NAME "ntp_adjtime"
+#else
+#ifdef LINUX
+#define NTP_ADJTIME adjtimex
+#define NTP_ADJTIME_NAME "adjtimex"
+#else
+#define NTP_ADJTIME ntp_adjtime
+#define NTP_ADJTIME_NAME "ntp_adjtime"
+#endif
+#endif
+
+/* Maximum frequency offset accepted by the kernel (in ppm) */
+#define MAX_FREQ 500.0
+
+/* Frequency scale to convert from ppm to the timex freq */
+#define FREQ_SCALE (double)(1 << 16)
+
+/* Threshold for the timex maxerror when the kernel sets the UNSYNC flag */
+#define MAX_SYNC_ERROR 16.0
+
+/* Minimum assumed rate at which the kernel updates the clock frequency */
+#define MIN_TICK_RATE 100
+
+/* Saved timex status */
+static int sys_status;
+
+/* Saved TAI-UTC offset */
+static int sys_tai_offset;
+
+/* ================================================== */
+
+static double
+convert_timex_frequency(const struct timex *txc)
+{
+  double freq_ppm;
+
+  freq_ppm = txc->freq / FREQ_SCALE;
+
+  return -freq_ppm;
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  struct timex txc;
+
+  txc.modes = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  return convert_timex_frequency(&txc);
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  struct timex txc;
+
+  txc.modes = MOD_FREQUENCY;
+  txc.freq = freq_ppm * -FREQ_SCALE;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  return convert_timex_frequency(&txc);
+}
+
+/* ================================================== */
+
+static void
+set_leap(int leap, int tai_offset)
+{
+  struct timex txc;
+  int applied, prev_status;
+
+  txc.modes = 0;
+  applied = SYS_Timex_Adjust(&txc, 0) == TIME_WAIT;
+
+  prev_status = sys_status;
+  sys_status &= ~(STA_INS | STA_DEL);
+
+  if (leap > 0)
+    sys_status |= STA_INS;
+  else if (leap < 0)
+    sys_status |= STA_DEL;
+
+  txc.modes = MOD_STATUS;
+  txc.status = sys_status;
+
+#ifdef MOD_TAI
+  if (tai_offset) {
+    txc.modes |= MOD_TAI;
+    txc.constant = tai_offset;
+
+    if (applied && !(sys_status & (STA_INS | STA_DEL)))
+      sys_tai_offset += prev_status & STA_INS ? 1 : -1;
+
+    if (sys_tai_offset != tai_offset) {
+      sys_tai_offset = tai_offset;
+      LOG(LOGS_INFO, "System clock TAI offset set to %d seconds", tai_offset);
+    }
+  }
+#endif
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  if (prev_status != sys_status) {
+    LOG(LOGS_INFO, "System clock status %s leap second",
+        leap ? (leap > 0 ? "set to insert" : "set to delete") :
+        (applied ? "reset after" : "set to not insert/delete"));
+  }
+}
+
+/* ================================================== */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  struct timex txc;
+
+  if (synchronised) {
+    if (est_error > MAX_SYNC_ERROR)
+      est_error = MAX_SYNC_ERROR;
+    if (max_error >= MAX_SYNC_ERROR) {
+      max_error = MAX_SYNC_ERROR;
+      synchronised = 0;
+    }
+  } else {
+    est_error = max_error = MAX_SYNC_ERROR;
+  }
+
+#ifdef LINUX
+  /* On Linux clear the UNSYNC flag only if rtcsync is enabled */
+  if (!CNF_GetRtcSync())
+    synchronised = 0;
+#endif
+
+  if (synchronised)
+    sys_status &= ~STA_UNSYNC;
+  else
+    sys_status |= STA_UNSYNC;
+
+  txc.modes = MOD_STATUS | MOD_ESTERROR | MOD_MAXERROR;
+  txc.status = sys_status;
+  txc.esterror = est_error * 1.0e6;
+  txc.maxerror = max_error * 1.0e6;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0)
+    ;
+}
+
+/* ================================================== */
+
+static void
+initialise_timex(void)
+{
+  struct timex txc;
+
+  sys_status = STA_UNSYNC;
+  sys_tai_offset = 0;
+
+  /* Reset PLL offset */
+  txc.modes = MOD_OFFSET | MOD_STATUS;
+  txc.status = STA_PLL | sys_status;
+  txc.offset = 0;
+  SYS_Timex_Adjust(&txc, 0);
+
+  /* Turn PLL off */
+  txc.modes = MOD_STATUS;
+  txc.status = sys_status;
+  SYS_Timex_Adjust(&txc, 0);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_Initialise(void)
+{
+  SYS_Timex_InitialiseWithFunctions(MAX_FREQ, 1.0 / MIN_TICK_RATE, NULL, NULL, NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_InitialiseWithFunctions(double max_set_freq_ppm, double max_set_freq_delay,
+                                  lcl_ReadFrequencyDriver sys_read_freq,
+                                  lcl_SetFrequencyDriver sys_set_freq,
+                                  lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                  double min_fastslew_offset, double max_fastslew_rate,
+                                  lcl_AccrueOffsetDriver sys_accrue_offset,
+                                  lcl_OffsetCorrectionDriver sys_get_offset_correction)
+{
+  initialise_timex();
+
+  SYS_Generic_CompleteFreqDriver(max_set_freq_ppm, max_set_freq_delay,
+                                 sys_read_freq ? sys_read_freq : read_frequency,
+                                 sys_set_freq ? sys_set_freq : set_frequency,
+                                 sys_apply_step_offset,
+                                 min_fastslew_offset, max_fastslew_rate,
+                                 sys_accrue_offset, sys_get_offset_correction,
+                                 set_leap, set_sync_status);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_Finalise(void)
+{
+  SYS_Generic_Finalise();
+}
+
+/* ================================================== */
+
+int
+SYS_Timex_Adjust(struct timex *txc, int ignore_error)
+{
+  int state;
+
+#ifdef SOLARIS
+  /* The kernel seems to check the constant even when it's not being set */
+  if (!(txc->modes & MOD_TIMECONST))
+    txc->constant = 10;
+#endif
+
+  state = NTP_ADJTIME(txc);
+
+  if (state < 0) {
+    LOG(ignore_error ? LOGS_DEBUG : LOGS_FATAL,
+        NTP_ADJTIME_NAME"(0x%x) failed : %s", txc->modes, strerror(errno));
+  }
+
+  return state;
+}
diff --git a/sys_timex.h b/sys_timex.h
new file mode 100644
index 0000000..b8617a2
--- /dev/null
+++ b/sys_timex.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for a driver based on the adjtimex()/ntp_adjtime() function
+  */
+
+#ifndef GOT_SYS_TIMEX_H
+#define GOT_SYS_TIMEX_H
+
+#include "localp.h"
+
+extern void SYS_Timex_Initialise(void);
+
+/* Initialise with some driver functions replaced with special versions */
+extern void SYS_Timex_InitialiseWithFunctions(double max_set_freq_ppm, double max_set_freq_delay,
+                                              lcl_ReadFrequencyDriver sys_read_freq,
+                                              lcl_SetFrequencyDriver sys_set_freq,
+                                              lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                              double min_fastslew_offset, double max_fastslew_rate,
+                                              lcl_AccrueOffsetDriver sys_accrue_offset,
+                                              lcl_OffsetCorrectionDriver sys_get_offset_correction);
+
+extern void SYS_Timex_Finalise(void);
+
+/* Wrapper for adjtimex()/ntp_adjtime() */
+extern int SYS_Timex_Adjust(struct timex *txc, int ignore_error);
+
+#endif  /* GOT_SYS_GENERIC_H */
diff --git a/sysincl.h b/sysincl.h
new file mode 100644
index 0000000..e26b236
--- /dev/null
+++ b/sysincl.h
@@ -0,0 +1,69 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file includes most system header files that the software
+  requires to better isolate system dependencies.
+  */
+
+#ifndef GOT_SYSINCL_H
+#define GOT_SYSINCL_H
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <float.h>
+#include <glob.h>
+#include <grp.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <math.h>
+#include <netinet/in.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/shm.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#if defined(LINUX) || defined(FREEBSD) || defined(NETBSD) || defined(SOLARIS) || defined(HAVE_MACOS_SYS_TIMEX)
+#include <sys/timex.h>
+#endif
+
+#ifdef HAVE_GETRANDOM
+#include <sys/random.h>
+#endif
+
+#endif /* GOT_SYSINCL_H */
diff --git a/tempcomp.c b/tempcomp.c
new file mode 100644
index 0000000..a468e33
--- /dev/null
+++ b/tempcomp.c
@@ -0,0 +1,176 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2011, 2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing temperature compensation.
+
+  */
+
+#include "config.h"
+
+#include "array.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "util.h"
+#include "logging.h"
+#include "sched.h"
+#include "tempcomp.h"
+
+/* Sanity limit (in ppm) */
+#define MAX_COMP 10.0
+
+static SCH_TimeoutID timeout_id;
+
+static LOG_FileID logfileid;
+
+static char *filename;
+static double update_interval;
+static double T0, k0, k1, k2;
+
+struct Point {
+  double temp;
+  double comp;
+};
+
+static ARR_Instance points;
+
+static double
+get_tempcomp(double temp)
+{
+  unsigned int i;
+  struct Point *p1 = NULL, *p2 = NULL;
+
+  /* If not configured with points, calculate the compensation from the
+     specified quadratic function */
+  if (!points)
+    return k0 + (temp - T0) * k1 + (temp - T0) * (temp - T0) * k2;
+
+  /* Otherwise interpolate/extrapolate between two nearest points */
+
+  for (i = 1; i < ARR_GetSize(points); i++) {
+    p2 = (struct Point *)ARR_GetElement(points, i);
+    if (p2->temp >= temp)
+      break;
+  }
+  p1 = p2 - 1;
+
+  return (temp - p1->temp) / (p2->temp - p1->temp) *
+         (p2->comp - p1->comp) + p1->comp;
+}
+
+static void
+read_timeout(void *arg)
+{
+  FILE *f;
+  double temp, comp;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'r', 0);
+
+  if (f && fscanf(f, "%lf", &temp) == 1) {
+    comp = get_tempcomp(temp);
+
+    if (fabs(comp) <= MAX_COMP) {
+      comp = LCL_SetTempComp(comp);
+
+      DEBUG_LOG("tempcomp updated to %f for %f", comp, temp);
+
+      if (logfileid != -1) {
+        struct timespec now;
+
+        LCL_ReadCookedTime(&now, NULL);
+        LOG_FileWrite(logfileid, "%s %11.4e %11.4e",
+            UTI_TimeToLogForm(now.tv_sec), temp, comp);
+      }
+    } else {
+      LOG(LOGS_WARN, "Temperature compensation of %.3f ppm exceeds sanity limit of %.1f",
+          comp, MAX_COMP);
+    }
+  } else {
+    LOG(LOGS_WARN, "Could not read temperature from %s", filename);
+  }
+
+  if (f)
+    fclose(f);
+
+  timeout_id = SCH_AddTimeoutByDelay(update_interval, read_timeout, NULL);
+}
+
+static void
+read_points(const char *filename)
+{
+  FILE *f;
+  char line[256];
+  struct Point *p;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'R', 0);
+
+  points = ARR_CreateInstance(sizeof (struct Point));
+
+  while (fgets(line, sizeof (line), f)) {
+    p = (struct Point *)ARR_GetNewElement(points);
+    if (sscanf(line, "%lf %lf", &p->temp, &p->comp) != 2) {
+      LOG_FATAL("Could not read tempcomp point from %s", filename);
+      break;
+    }
+  }
+
+  fclose(f);
+
+  if (ARR_GetSize(points) < 2)
+    LOG_FATAL("Not enough points in %s", filename);
+}
+
+void
+TMC_Initialise(void)
+{
+  char *point_file;
+
+  CNF_GetTempComp(&filename, &update_interval, &point_file, &T0, &k0, &k1, &k2);
+
+  if (filename == NULL)
+    return;
+
+  if (update_interval <= 0.0)
+    update_interval = 1.0;
+
+  if (point_file)
+    read_points(point_file);
+
+  logfileid = CNF_GetLogTempComp() ? LOG_FileOpen("tempcomp",
+      "   Date (UTC) Time        Temp.       Comp.")
+    : -1;
+
+  read_timeout(NULL);
+}
+
+void
+TMC_Finalise(void)
+{
+  if (filename == NULL)
+    return;
+
+  if (points)
+    ARR_DestroyInstance(points);
+
+  SCH_RemoveTimeout(timeout_id);
+}
diff --git a/tempcomp.h b/tempcomp.h
new file mode 100644
index 0000000..b876f90
--- /dev/null
+++ b/tempcomp.h
@@ -0,0 +1,29 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2011
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for temperature compensation.
+
+  */
+
+extern void TMC_Initialise(void);
+extern void TMC_Finalise(void);
diff --git a/test/compilation/001-features b/test/compilation/001-features
new file mode 100755
index 0000000..9bd340f
--- /dev/null
+++ b/test/compilation/001-features
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+# Try to compile chrony in various combinations of disabled features
+
+cd ../..
+
+export CFLAGS="-O2 -Werror -Wpointer-arith -Wformat-signedness -Wno-unknown-warning-option -D_FORTIFY_SOURCE=2"
+
+for opts in \
+	"--enable-debug" \
+	"--enable-ntp-signd" \
+	"--enable-scfilter" \
+	"--disable-asyncdns" \
+	"--disable-ipv6" \
+	"--disable-privdrop" \
+	"--disable-readline" \
+	"--disable-rtc" \
+	"--disable-sechash" \
+	"--disable-cmdmon" \
+	"--disable-cmdmon --enable-scfilter" \
+	"--disable-ntp" \
+	"--disable-ntp --enable-scfilter" \
+	"--disable-nts" \
+	"--disable-refclock" \
+	"--disable-timestamping" \
+	"--disable-timestamping --disable-ntp" \
+	"--disable-cmdmon --disable-ntp" \
+	"--disable-cmdmon --disable-ntp --enable-scfilter" \
+	"--disable-cmdmon --disable-refclock" \
+	"--disable-cmdmon --disable-ntp --disable-refclock"
+do
+	./configure $opts || exit 1
+	make clean
+	make "$@" || exit 1
+	make -C test/unit check || exit 1
+done
diff --git a/test/compilation/002-scanbuild b/test/compilation/002-scanbuild
new file mode 100755
index 0000000..35a3faf
--- /dev/null
+++ b/test/compilation/002-scanbuild
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+cd ../..
+
+for opts in \
+	"--host-system=Linux" \
+	"--host-system=NetBSD" \
+	"--host-system=FreeBSD" \
+	"--without-nettle" \
+	"--without-nettle --without-nss" \
+	"--without-nettle --without-nss --without-tomcrypt" \
+	"--without-nettle --without-nss --without-tomcrypt --without-gnutls"
+do
+	./configure $opts
+	scan-build make "$@" || exit 1
+done
diff --git a/test/compilation/003-sanitizers b/test/compilation/003-sanitizers
new file mode 100755
index 0000000..8040efe
--- /dev/null
+++ b/test/compilation/003-sanitizers
@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+# Run the unit and simulation tests with different compiler sanitizers
+# and under valgrind
+
+valgrind_opts="--leak-check=full --errors-for-leak-kinds=definite"
+
+cd ../..
+
+if [ "$(uname -sm)" != "Linux x86_64" ]; then
+  echo Test supported on Linux x86_64 only
+  exit 1
+fi
+
+[ -f /etc/os-release ] && . /etc/os-release
+
+if [ "$ID" = "fedora" ]; then
+  echo Checking test dependencies:
+  rpm -q {gcc,clang}.x86_64 {valgrind,libgcc,clang-libs}.{x86_64,i686} || exit 1
+  rpm -q {libseccomp,nettle,nss-softokn-freebl,libtomcrypt,gnutls}-devel.{x86_64,i686} || exit 1
+  echo
+fi
+
+touch Makefile
+
+for extra_config_opts in \
+  "--all-privops" \
+  "--disable-ipv6" \
+  "--disable-scfilter" \
+  "--without-gnutls" \
+  "--without-nettle" \
+  "--without-nettle --without-nss" \
+  "--without-nettle --without-nss --without-tomcrypt" \
+  "--without-nettle --without-nss --without-tomcrypt --without-gnutls"; \
+do
+  for arch_opts in "-m32" ""; do
+    pushd test/simulation/clknetsim || exit 1
+    make clean > /dev/null 2>&1
+    CFLAGS="$arch_opts -DCLKNETSIM_DISABLE_SYSCALL" make "$@" || exit 1
+    echo
+
+    popd
+
+    for CC in gcc clang; do
+      export CC
+
+      for san_options in "" "-fsanitize=address" "-fsanitize=memory"; do
+        export CFLAGS="-O2 -g -fsanitize=undefined -fsanitize=float-divide-by-zero -fno-sanitize-recover=undefined,float-divide-by-zero $san_options $arch_opts"
+
+        # clang msan doesn't work on i686 and otherwise requires patches
+        echo $CFLAGS | grep -q 'sanitize=memory' && continue
+
+        [ -n "$TEST_NO_M32_CLANG" -a "$arch_opts" = "-m32" -a "$CC" = "clang" ] && continue
+
+        [ -n "$TEST_GCC_STATIC_ASAN" -a "$CC" = "gcc" ] &&
+                echo $CFLAGS | grep -q 'sanitize=address' && CFLAGS="$CFLAGS -static-libasan"
+
+        config_opts="--with-user=chrony --with-ntp-era=1000000000 --enable-debug --enable-scfilter --enable-ntp-signd $extra_config_opts"
+
+        echo -----------------------------------------------------------------------------
+        echo CC=\"$CC\" CFLAGS=\"$CFLAGS\" ./configure $config_opts
+
+        make distclean > /dev/null 2>&1
+
+        ./configure $config_opts || exit 1
+
+        if echo "$config_opts" | grep -q all-privops; then
+          for op in ADJUSTTIME ADJUSTTIMEX SETTIME BINDSOCKET; do
+            echo "#define PRIVOPS_$op 1" >> config.h
+          done
+        fi
+
+        make "$@" || exit 1
+
+        [ -n "$TEST_BUILD_ONLY" ] && continue
+
+        echo
+        pushd test/unit || exit 1
+        make "$@" || exit 1
+        if [ "$san_options" = "" ]; then
+          make check TEST_WRAPPER="valgrind $valgrind_opts --error-exitcode=1" || exit 1
+        else
+          make check || exit 1
+        fi
+        popd
+
+        [ -n "$TEST_UNIT_ONLY" ] && continue
+
+        echo
+        pushd test/simulation || exit 1
+        export CLKNETSIM_RANDOM_SEED=101
+        if [ "$arch_opts" = "" -a "$san_options" = "" ]; then
+          CLKNETSIM_CLIENT_WRAPPER="valgrind $valgrind_opts" ./run -i 1 || exit 1
+        elif [ "$CC" = "gcc" ] && ! echo $CFLAGS | grep -q "-static-libasan"; then
+          libasan=$(ldd ../../chronyd | grep -o '/.*lib.*/libasan.so.[0-9]')
+          CLKNETSIM_PRELOAD=$libasan ./run -i 1 || exit 1
+        else
+          ./run -i 1 || exit 1
+        fi
+        popd
+      done
+    done
+  done
+done
diff --git a/test/kernel/Makefile b/test/kernel/Makefile
new file mode 100644
index 0000000..6ec8341
--- /dev/null
+++ b/test/kernel/Makefile
@@ -0,0 +1,7 @@
+CFLAGS=-O2 -Wall
+PROGS=adjtime ntpadjtime
+
+all: $(PROGS)
+
+clean:
+	rm -f $(PROGS)
diff --git a/test/kernel/adjtime.c b/test/kernel/adjtime.c
new file mode 100644
index 0000000..0ca8ff2
--- /dev/null
+++ b/test/kernel/adjtime.c
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+/* Test the system adjtime() function. Check the range of supported offset,
+   support for readonly operation, and slew rate with different update
+   intervals and offsets. */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+static int
+diff_tv(struct timeval *tv1, struct timeval *tv2)
+{
+  return 1000000 * (tv1->tv_sec - tv2->tv_sec) + (tv1->tv_usec - tv2->tv_usec);
+}
+
+static struct timeval
+usec_to_tv(int usec)
+{
+  struct timeval tv;
+
+  tv.tv_sec = usec / 1000000;
+  tv.tv_usec = usec % 1000000;
+
+  return tv;
+}
+
+static int
+try_adjtime(struct timeval *new, struct timeval *old)
+{
+  int r;
+
+  r = adjtime(new, old);
+  if (r)
+    printf("adjtime() failed : %s ", strerror(errno));
+  return r;
+}
+
+static void
+reset_adjtime(void)
+{
+  struct timeval tv;
+
+  tv = usec_to_tv(0);
+  try_adjtime(&tv, NULL);
+}
+
+static void
+test_range(void)
+{
+  struct timeval tv;
+  int i;
+
+  printf("range:\n");
+
+  for (i = 0; i < sizeof (time_t) * 8; i++) {
+    tv.tv_usec = 0;
+    tv.tv_sec = (1ULL << i) - 1;
+    printf("%20lld s : ", (long long)tv.tv_sec);
+    printf("%s\n", !try_adjtime(&tv, NULL) ? "ok" : "");
+    tv.tv_sec = ~tv.tv_sec;
+    printf("%20lld s : ", (long long)tv.tv_sec);
+    printf("%s\n", !try_adjtime(&tv, NULL) ? "ok" : "");
+  }
+}
+
+static void
+test_readonly(void)
+{
+  struct timeval tv1, tv2;
+  int i, r;
+
+  printf("readonly:\n");
+
+  for (i = 0; i <= 20; i++) {
+    tv1 = usec_to_tv(1 << i);
+
+    printf("%9d us : ", 1 << i);
+    try_adjtime(&tv1, NULL);
+    r = !try_adjtime(NULL, &tv2) && !diff_tv(&tv1, &tv2);
+    printf("%s\n", r ? "ok" : "fail");
+  }
+}
+
+static void
+test_readwrite(void)
+{
+  struct timeval tv1, tv2, tv3;
+  int i, r;
+
+  printf("readwrite:\n");
+
+  for (i = 0; i <= 20; i++) {
+    tv1 = usec_to_tv(1 << i);
+    tv3 = usec_to_tv(0);
+
+    printf("%9d us : ", 1 << i);
+    try_adjtime(&tv1, NULL);
+    r = !try_adjtime(&tv3, &tv2) && !diff_tv(&tv1, &tv2);
+    printf("%s\n", r ? "ok" : "fail");
+  }
+}
+
+static void
+xusleep(int usec)
+{
+  struct timeval tv;
+
+  tv = usec_to_tv(usec);
+  select(0, NULL, NULL, NULL, &tv);
+}
+
+static void
+test_slew(void)
+{
+  struct timeval tv1, tv2, tv3;
+  int i, j, k, diff, min, has_min;
+
+  printf("slew:\n");
+
+  for (i = 9; i <= 20; i++) {
+    printf("%9d us : ", 1 << i);
+    for (j = 4; j <= 20; j += 4) {
+      for (min = has_min = 0, k = 4; k < 16; k += 2) {
+
+        tv1 = usec_to_tv(1 << j);
+        tv3 = usec_to_tv(0);
+
+        xusleep(1 << i);
+        reset_adjtime();
+
+        xusleep(1 << i);
+        if (try_adjtime(&tv1, NULL))
+          continue;
+
+        xusleep(1 << i);
+        if (try_adjtime(&tv3, &tv2))
+          continue;
+
+        diff = diff_tv(&tv1, &tv2);
+        if (!has_min || min > diff) {
+          min = diff;
+          has_min = 1;
+        }
+      }
+
+      if (!has_min)
+        continue;
+
+      printf(" %5d (%d)", min, 1 << j);
+      fflush(stdout);
+    }
+    printf("\n");
+  }
+}
+
+int
+main()
+{
+  test_range();
+  test_readonly();
+  test_readwrite();
+  test_slew();
+
+  reset_adjtime();
+
+  return 0;
+}
diff --git a/test/kernel/ntpadjtime.c b/test/kernel/ntpadjtime.c
new file mode 100644
index 0000000..4af96b4
--- /dev/null
+++ b/test/kernel/ntpadjtime.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+/* Check the frequency range of the system ntp_adjtime() implementation */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+
+static int
+try_ntpadjtime(struct timex *t)
+{
+  int r;
+  r = ntp_adjtime(t);
+  if (r < 0)
+    printf("ntp_adjtime() failed : %s ", strerror(errno));
+  return r;
+}
+
+static void
+reset_ntpadjtime(void)
+{
+  struct timex t;
+
+  t.modes = MOD_OFFSET | MOD_FREQUENCY;
+  t.offset = 0;
+  t.freq = 0;
+  try_ntpadjtime(&t);
+}
+
+static void
+test_freqrange(void)
+{
+  struct timex t;
+  int i;
+
+  printf("freq range:\n");
+
+  for (i = -1000; i <= 1000; i += 50) {
+    t.modes = MOD_FREQUENCY;
+    t.freq = i * (1 << 16);
+    printf("%4d ppm => ", i);
+    if (try_ntpadjtime(&t) < 0)
+      continue;
+
+    printf("%4ld ppm : ", t.freq / (1 << 16));
+    printf("%s\n", t.freq == i * (1 << 16) ? "ok" : "fail");
+  }
+}
+
+int
+main()
+{
+  test_freqrange();
+
+  reset_ntpadjtime();
+
+  return 0;
+}
diff --git a/test/simulation/001-defaults b/test/simulation/001-defaults
new file mode 100755
index 0000000..b39d95c
--- /dev/null
+++ b/test/simulation/001-defaults
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "default test settings"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/002-largenetwork b/test/simulation/002-largenetwork
new file mode 100755
index 0000000..a9e0ad8
--- /dev/null
+++ b/test/simulation/002-largenetwork
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large network"
+
+time_rms_limit=5e-4
+
+server_strata=3
+servers=4
+clients=5
+
+client_start=2000
+min_sync_time=2100
+max_sync_time=2300
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/003-largefreqoffset b/test/simulation/003-largefreqoffset
new file mode 100755
index 0000000..9381b1a
--- /dev/null
+++ b/test/simulation/003-largefreqoffset
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large frequency offset"
+
+max_sync_time=1000
+
+for freq_offset in -5e-2 -5e-3 5e-3 5e-2; do
+	# Adjust offset so it's close to 0 on first clock update
+	time_offset=$(awk "BEGIN {print -($freq_offset * 130)}")
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/004-largetimeoffset b/test/simulation/004-largetimeoffset
new file mode 100755
index 0000000..4aebdd3
--- /dev/null
+++ b/test/simulation/004-largetimeoffset
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large time offset"
+
+min_sync_time=1300
+max_sync_time=1400
+
+for time_offset in -1e2 1e2; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/005-externalstep b/test/simulation/005-externalstep
new file mode 100755
index 0000000..e6fff26
--- /dev/null
+++ b/test/simulation/005-externalstep
@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "external time step"
+
+min_sync_time=1500
+max_sync_time=1550
+
+for step in -1e2 1e2; do
+	# Make one step in 150th second
+	client_step="(* $step (equal 0.1 (sum 1.0) 150))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=5120
+max_sync_time=6200
+client_conf="makestep 1 -1"
+
+for step in -1e8 -1e5 1e5 1e8; do
+	# Make one step in 5000th second
+	client_step="(* $step (equal 0.1 (sum 1.0) 5000))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+time_max_limit=2e4
+time_rms_limit=8e3
+
+for step in -1e4 1e4; do
+	# Make a step every 500 seconds
+	client_step="(* $step (equal 0.1 (% (sum 1.0) 500) 0))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/006-largejitter b/test/simulation/006-largejitter
new file mode 100755
index 0000000..36ae5e2
--- /dev/null
+++ b/test/simulation/006-largejitter
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large jitter"
+
+time_offset=1e0
+jitter=1e-1
+
+time_max_limit=5e-1
+freq_max_limit=2e-1
+time_rms_limit=1e-1
+freq_rms_limit=5e-3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/007-largewander b/test/simulation/007-largewander
new file mode 100755
index 0000000..af0c599
--- /dev/null
+++ b/test/simulation/007-largewander
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large wander"
+
+wander=1e-7
+
+time_max_limit=5e-3
+freq_max_limit=5e-3
+time_rms_limit=1e-3
+freq_rms_limit=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/008-ntpera b/test/simulation/008-ntpera
new file mode 100755
index 0000000..2eea63b
--- /dev/null
+++ b/test/simulation/008-ntpera
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "NTP eras"
+
+if check_config_h 'HAVE_LONG_TIME_T 1'; then
+	ntp_start=$(awk "BEGIN {print $(grep NTP_ERA_SPLIT ../../config.h | tr -dc '0-9*+-')}")
+else
+	ntp_start="-2147483648"
+fi
+
+# Set the starting test date to 500 seconds before the second NTP era.
+# This should work with 32-bit time_t and also with 64-bit time_t if the
+# configured NTP interval covers the test interval.
+export CLKNETSIM_START_DATE=$(date -d 'Feb  7 06:19:56 UTC 2036' +'%s')
+
+if awk "BEGIN {exit !($ntp_start <= $CLKNETSIM_START_DATE && \
+		$CLKNETSIM_START_DATE + $limit < $ntp_start + 2^32)}"; then
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+fi
+
+# The following tests need 64-bit time_t and ntp_start not before 1970
+check_config_h 'HAVE_LONG_TIME_T 1' || test_skip
+echo "$ntp_start" | grep -q '-' && test_skip
+
+for time_offset in -1e-1 1e-1; do
+	for start_offset in 0 "2^32 - $limit"; do
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync || test_fail
+	done
+
+	for start_offset in -$limit "2^32"; do
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync && test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/009-sourceselection b/test/simulation/009-sourceselection
new file mode 100755
index 0000000..547c376
--- /dev/null
+++ b/test/simulation/009-sourceselection
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "source selection"
+
+# Falsetickers should be detected if their number is less than half of all
+
+base_delay=1e-3
+servers=5
+
+for falsetickers in 1 2; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+for falsetickers in 3 4; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	# These check are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+# Sources with large asymmetric delay should be excluded
+
+servers=3
+falsetickers=0
+base_delay="(+ 1e-3 (equal 0.1 to 2) (equal 0.1 to 3))"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/010-multrecv b/test/simulation/010-multrecv
new file mode 100755
index 0000000..36e7476
--- /dev/null
+++ b/test/simulation/010-multrecv
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+export CLKNETSIM_RECV_MULTIPLY=4
+
+test_start "multiple received packets"
+
+limit=50000
+client_server_options="minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/011-asymjitter b/test/simulation/011-asymjitter
new file mode 100755
index 0000000..9fb5567
--- /dev/null
+++ b/test/simulation/011-asymjitter
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "asymmetric jitter"
+
+jitter=5e-4
+jitter_asymmetry=0.47
+limit=100000
+max_sync_time=2000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/012-daemonts b/test/simulation/012-daemonts
new file mode 100755
index 0000000..a1b90e3
--- /dev/null
+++ b/test/simulation/012-daemonts
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "daemon timestamping"
+
+export CLKNETSIM_TIMESTAMPING=0
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/013-nameserv b/test/simulation/013-nameserv
new file mode 100755
index 0000000..941026b
--- /dev/null
+++ b/test/simulation/013-nameserv
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "name resolving"
+
+dns=1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/101-poll b/test/simulation/101-poll
new file mode 100755
index 0000000..1416b22
--- /dev/null
+++ b/test/simulation/101-poll
@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "minpoll/maxpoll options"
+
+wander=0.0
+jitter=1e-6
+
+time_max_limit=1e-5
+freq_max_limit=1e-5
+time_rms_limit=5e-6
+freq_rms_limit=5e-6
+client_conf="makestep 1e-2 1"
+
+for poll in $(seq 1 14); do
+	client_server_options="minpoll $poll maxpoll $poll"
+	limit=$[2**$poll * 10]
+	min_sync_time=$[2**$poll * 2]
+	max_sync_time=$[2**$poll * 21 / 10 + 1]
+	client_max_min_out_interval=$(awk "BEGIN {print 2^$poll * 1.1}")
+	client_min_mean_out_interval=$(awk "BEGIN {print 2^$poll * 0.99}")
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+client_max_min_out_interval=$default_client_max_min_out_interval
+client_min_mean_out_interval=$default_client_min_mean_out_interval
+
+limit=10
+
+for poll in $(seq -7 2 -1); do
+	client_server_options="minpoll $poll maxpoll $poll"
+
+	base_delay=1e-4
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_file_messages "	2	1	" \
+		$[2**-poll * limit * 9 / 10] $[2**-poll * limit] log.packets || test_fail
+
+	base_delay=2e-2
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_file_messages "	2	1	" $[limit * 9 / 10] $limit log.packets || test_fail
+done
+
+test_pass
diff --git a/test/simulation/102-iburst b/test/simulation/102-iburst
new file mode 100755
index 0000000..9936572
--- /dev/null
+++ b/test/simulation/102-iburst
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "iburst option"
+
+freq_offset=1e-4
+
+client_conf="makestep 1e-2 1
+driftfile tmp/drift"
+client_server_options="iburst"
+
+min_sync_time=4
+max_sync_time=6
+
+echo "100 1.0" > tmp/drift
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/103-initstepslew b/test/simulation/103-initstepslew
new file mode 100755
index 0000000..fe47b68
--- /dev/null
+++ b/test/simulation/103-initstepslew
@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "initstepslew directive"
+
+freq_offset=0.0
+wander=0.0
+time_rms_limit=1e-3
+limit=100
+
+client_conf="initstepslew 5 192.168.123.1"
+client_server_conf="#"
+
+min_sync_time=6
+max_sync_time=35
+
+for time_offset in -2.0 -0.2 0.2 2.0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	check_log_messages "00:00:0.Z System's initial.*slew" 1 1 || test_fail
+done
+
+min_sync_time=5
+max_sync_time=5
+
+for time_offset in -1e8 -1e2 1e2 1e8; do
+	run_test || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	check_log_messages "System's initial.*step" 1 1 || test_fail
+done
+
+time_offset=3
+limit=500
+servers=2
+falsetickers=1
+client_conf="initstepslew 5 192.168.123.1 192.168.123.2"
+client_server_conf="server 192.168.123.2"
+
+min_sync_time=360
+max_sync_time=450
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_log_messages "00:03:2.Z No suitable source for initstepslew" 1 1 || test_fail
+
+client_conf="initstepslew 5 192.168.123.1 192.168.123.2"
+
+min_sync_time=1
+max_sync_time=500
+server_conf="deny all"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync && test_fail
+check_log_messages "00:00:1.Z No suitable source for initstepslew" 1 1 || test_fail
+
+test_pass
diff --git a/test/simulation/104-driftfile b/test/simulation/104-driftfile
new file mode 100755
index 0000000..93d4363
--- /dev/null
+++ b/test/simulation/104-driftfile
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "driftfile directive"
+
+servers=0
+time_offset=0.0
+wander=0.0
+limit=10
+freq_max_limit=1e-9
+min_sync_time=1
+max_sync_time=1
+client_conf="driftfile tmp/drift"
+
+for freq_offset in -5e-2 -5e-4 -5e-6 5e-6 5e-4 5e-2; do
+	awk "BEGIN {printf \"%.9e 1\", 1e6 - 1 / (1 + $freq_offset) * 1e6}" > tmp/drift
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/105-ntpauth b/test/simulation/105-ntpauth
new file mode 100755
index 0000000..1f228f5
--- /dev/null
+++ b/test/simulation/105-ntpauth
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP authentication"
+
+server_conf="keyfile tmp/server.keys"
+client_conf="keyfile tmp/client.keys"
+
+cat > tmp/server.keys <<-EOF
+1 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+2 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+3 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+4 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+EOF
+
+cat > tmp/client.keys <<-EOF
+1 k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+2 ASCII:k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+3 MD5 ASCII:k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+4 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+EOF
+
+keys=4
+
+types="MD5"
+check_config_h 'FEAT_SECHASH 1' && types="$types SHA1 SHA256 SHA384 SHA512"
+check_config_h 'HAVE_CMAC 1' && types="$types AES128 AES256"
+
+for type in $types; do
+	keys=$[$keys + 1]
+	case $type in
+		AES128)	length=16;;
+		AES256)	length=32;;
+		*)	length=$[$RANDOM % 32 + 1];;
+	esac
+
+	key=$(echo $keys $type HEX:$(tr -c -d '0-9A-F' < /dev/urandom 2> /dev/null | \
+		head -c $[$length * 2]))
+	echo "$key" >> tmp/server.keys
+	echo "$key" >> tmp/client.keys
+done
+
+for version in 3 4; do
+	for key in $(seq $keys); do
+		client_server_options="version $version key $key"
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync || test_fail
+	done
+done
+
+server_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the server doesn't know the key
+check_sync && test_fail
+check_packet_interval || test_fail
+
+server_conf="keyfile tmp/server.keys"
+client_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the client doesn't know the key
+check_sync && test_fail
+check_packet_interval || test_fail
+
+client_conf="keyfile tmp/client.keys"
+clients=2
+peers=2
+max_sync_time=500
+base_delay="$default_base_delay (* -1 (equal 0.1 from 3) (equal 0.1 to 1))"
+
+for versions in "3 3" "3 4" "4 3" "4 4"; do
+	for key in 1 $keys; do
+		client_lpeer_options="version ${versions% *} key $key"
+		client_rpeer_options="version ${versions#* } key $key"
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_sync || test_fail
+	done
+done
+
+client_lpeer_options="key 1"
+client_rpeer_options="key 2"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the peers are using different keys"
+check_sync && test_fail
+
+test_pass
diff --git a/test/simulation/106-refclock b/test/simulation/106-refclock
new file mode 100755
index 0000000..f09f170
--- /dev/null
+++ b/test/simulation/106-refclock
@@ -0,0 +1,143 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "SHM refclock"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+check_config_h 'FEAT_PHC 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+export CLKNETSIM_PHC_DELAY=1e-6
+export CLKNETSIM_PHC_JITTER=1e-7
+
+servers=0
+limit=1000
+refclock_jitter=$jitter
+min_sync_time=45
+max_sync_time=70
+chronyc_start=70
+chronyc_conf="tracking"
+
+for refclock in "SHM 0" "PHC /dev/ptp0" "PHC /dev/ptp0:nocrossts"; do
+	client_conf="refclock $refclock stratum 3 delay 1e-3 refid GPS
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*47505300 \(GPS\)
+Stratum.*: 4
+.*
+Root delay      : 0.001000000 seconds
+.*
+Update interval : 16\.. seconds
+.*$" || test_fail
+
+	if echo "$refclock" | grep -q 'PHC.*nocrossts'; then
+		check_file_messages "20.* GPS.*[0-9] N " 650 750 refclocks.log || test_fail
+	else
+		check_file_messages "20.* GPS.*[0-9] N " 997 1001 refclocks.log || test_fail
+	fi
+	check_file_messages "20.* GPS.*- N " 61 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+done
+
+if check_config_h 'FEAT_PPS 1'; then
+	refclock_offset=0.35
+	refclock_jitter=0.05
+
+	client_conf="
+refclock SHM 0 refid NMEA noselect
+refclock PPS /dev/pps0 lock NMEA
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 1
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 620 740 refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 60 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+
+	client_conf="
+refclock SHM 0 noselect
+refclock PPS /dev/pps0
+local
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 10
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 997 1001 refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 60 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+
+	min_sync_time=100
+	max_sync_time=220
+	chronyc_start=220
+	client_conf="
+refclock SHM 0 refid NMEA offset 0.35 delay 0.1
+refclock PPS /dev/pps0
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 1
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 800 940  refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 50 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+fi
+
+refclock_offset="(+ 0.399 (sum 1e-3))"
+refclock_jitter=1e-6
+servers=1
+freq_offset="(* 1e-4 (sine 1000))"
+base_delay="(* -1.0 (equal 0.1 (min time 5000) 5000))"
+client_server_options="minpoll 4 maxpoll 4 filter 5 minsamples 64"
+client_conf="
+refclock PHC /dev/ptp0 local poll 2
+logdir tmp
+log refclocks tracking"
+chronyc_conf=""
+limit=10000
+max_sync_time=5000
+time_max_limit=1e-3
+time_rms_limit=5e-4
+freq_max_limit=2e-5
+freq_rms_limit=5e-6
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+check_file_messages "20.* PHC0 .* [0-9] ? " 9999 10001 refclocks.log || test_fail
+check_file_messages "20.* PHC0 .* - ? " 2499 2501 refclocks.log || test_fail
+check_file_messages "20.* PHC0 " 0 0 tracking.log || test_fail
+rm -f tmp/refclocks.log tmp/tracking.log
+
+test_pass
diff --git a/test/simulation/107-allowdeny b/test/simulation/107-allowdeny
new file mode 100755
index 0000000..4665337
--- /dev/null
+++ b/test/simulation/107-allowdeny
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "allow/deny directives"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=500
+
+# Note that start_client in clknetsim.bash always adds allow to the config
+
+for server_conf in \
+	"deny" \
+	"deny all" \
+	"deny 192.168.0.0/16" \
+	"deny 192.168.123" \
+	"deny 192.168.123.2" \
+	"deny all
+allow 192.168.124.0/24"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	# These checks are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+for server_conf in \
+	"deny all
+allow" \
+	"deny all
+allow all" \
+	"deny all
+allow 192.168.123" \
+	"deny all
+allow 192.168.123/24" \
+	"deny 192.168.124.0/24"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/108-peer b/test/simulation/108-peer
new file mode 100755
index 0000000..906de17
--- /dev/null
+++ b/test/simulation/108-peer
@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP peers"
+
+# Allow and drop packets to the server in 1000 second intervals, so only one
+# client has access to it and the other is forced to switch to the peer.
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (% time 2000) 1000) 1000))
+     (* -1
+        (equal 0.1 from 3)
+        (equal 0.1 to 1)
+	(equal 0.1 (max (% time 2000) 1000) 1000)))
+EOF
+)
+
+clients=2
+peers=2
+max_sync_time=1000
+client_server_options="minpoll 6 maxpoll 6"
+client_peer_options="minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))"
+client_peer_options=""
+
+while read lminpoll lmaxpoll rminpoll rmaxpoll max_sync_time; do
+	client_lpeer_options="minpoll $lminpoll maxpoll $lmaxpoll"
+	client_rpeer_options="minpoll $rminpoll maxpoll $rmaxpoll"
+	limit=$[$max_sync_time * 10]
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_sync || test_fail
+done <<-EOF
+	3 6 3 6 400
+	3 3 6 6 450
+	6 6 3 3 450
+	3 6 6 6 450
+	6 6 3 6 450
+	-2 -2 2 2 220
+	2 2 -2 -2 220
+EOF
+
+test_pass
diff --git a/test/simulation/109-makestep b/test/simulation/109-makestep
new file mode 100755
index 0000000..78d8d59
--- /dev/null
+++ b/test/simulation/109-makestep
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "makestep directive"
+
+client_conf="makestep 0 -1
+corrtimeratio 1e10"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+limit=200
+jitter=1e-5
+client_conf="makestep 2 1"
+
+min_sync_time=130
+max_sync_time=150
+
+for time_offset in -1.0 -0.1 0.1 1.0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=120
+max_sync_time=140
+
+for time_offset in -1e8 -1e2 1e2 1e8; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/110-chronyc b/test/simulation/110-chronyc
new file mode 100755
index 0000000..b78f0d8
--- /dev/null
+++ b/test/simulation/110-chronyc
@@ -0,0 +1,496 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "chronyc"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+refclock_jitter=$jitter
+client_server_conf="
+server node1.net1.clk
+server 192.168.123.2"
+client_conf="
+refclock SHM 0 noselect
+smoothtime 400 0.001 leaponly"
+cmdmon_unix=0
+
+chronyc_conf="activity
+tracking
+sourcename 192.168.123.1
+sourcename 192.168.123.2
+sources
+sourcestats
+manual list
+smoothing
+waitsync
+rtcdata"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+2 sources online
+0 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address
+Reference ID    : C0A87B01 \(192\.168\.123\.1\)
+Stratum         : 2
+Ref time \(UTC\)  : Fri Jan 01 00:1.:.. 2010
+System time     : 0\.0000..... seconds (slow|fast) of NTP time
+Last offset     : [+-]0\.000...... seconds
+RMS offset      : 0\.000...... seconds
+Frequency       : (99|100)\.... ppm fast
+Residual freq   : [+-][0-9]\.... ppm
+Skew            : [0-9]\.... ppm
+Root delay      : 0\.000...... seconds
+Root dispersion : 0\.000...... seconds
+Update interval : [0-9]+\.. seconds
+Leap status     : Normal
+node1\.net1\.clk
+192\.168\.123\.2
+MS Name/IP address         Stratum Poll Reach LastRx Last sample               
+===============================================================================
+#\? SHM0                          0   4   377    [0-9]+ [0-9 +-]+[un]s\[[0-9 +-]+[un]s\] \+/-[ 0-9]+[un]s
+\^\* 192\.168\.123\.1                 1   [67]   377    [0-9]+ [0-9 +-]+[un]s\[[0-9 +-]+[un]s\] \+/-[ 0-9]+[un]s
+\^\? 192\.168\.123\.2                 0   [0-9]+     0     -     \+0ns\[   \+0ns\] \+/-    0ns
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+SHM0                       [0-9 ]+ [0-9 ]+ [0-9 ]+ [ +-][01]\.... [0-9 ]+\....  [0-9 +-]+[un]s [0-9 ]+[un]s
+192\.168\.123\.1              [0-9 ]+ [0-9 ]+ [0-9 ]+ [ +-][01]\.... [0-9 ]+\....  [0-9 +-]+[un]s [0-9 ]+[un]s
+192\.168\.123\.2               0   0     0     \+0\.000   2000\.000     \+0ns  4000ms
+210 n_samples = 0
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+Active         : Yes \(leap second only\)
+Offset         : \+0\.000000000 seconds
+Frequency      : \+0\.000000 ppm
+Wander         : \+0\.000000 ppm per second
+Last update    : [0-9]+\.. seconds ago
+Remaining time : 0\.0 seconds
+try: 1, refid: C0A87B01, correction: 0\.000......, skew: .\....
+513 RTC driver not running$" \
+|| test_fail
+
+chronyc_conf="tracking"
+dns=1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^Reference ID    : C0A87B01 \(node1\.net1\.clk\)" \
+	|| test_fail
+
+chronyc_options="-c"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^C0A87B01,192\.168\.123\.1,2,12623049..\..........,-?0\.0000.....,-?0\.000......,0\.000......,(99|100)\....,-?[0-9]\....,[0-9]\....,0\.000......,0\.000......,[0-9]+\..,Normal$" \
+	|| test_fail
+
+chronyc_options=""
+server_strata=0
+chronyc_start=0.5
+client_server_conf=""
+client_conf=""
+server_conf="server 192.168.123.1"
+limit=1
+
+for chronyc_conf in \
+	"accheck 1.2.3.4" \
+	"add peer 10.0.0.0 minpoll 2 maxpoll 6" \
+	"add server 10.0.0.0 minpoll 6 maxpoll 10 iburst burst key 1 certset 2 maxdelay 1e-3 maxdelayratio 10.0 maxdelaydevratio 10.0 maxdelayquant 0.5 mindelay 1e-4 asymmetry 0.5 offset 1e-5 minsamples 6 maxsamples 6 filter 3 offline auto_offline prefer noselect trust require xleave polltarget 20 port 123 presend 7 minstratum 3 version 4 nts ntsport 4460 copy extfield F323" \
+	"add server node1.net1.clk" \
+	"allow 1.2.3.4" \
+	"allow 1.2" \
+	"allow 3.4.5" \
+	"allow 6.7.8/22" \
+	"allow 6.7.8.9/22" \
+	"allow 0/0" \
+	"allow" \
+	"allow all 10/24" \
+	"authdata" \
+	"burst 5/10" \
+	"burst 3/5 255.255.255.0/1.2.3.0" \
+	"burst 1/2 1.2.3.0/24" \
+	"clients" \
+	"clients -k" \
+	"clients -p 100" \
+	"clients -r" \
+	"cmdaccheck 1.2.3.4" \
+	"cmdallow 1.2.3.4" \
+	"cmdallow all 1.2.3.0/24" \
+	"cmddeny 1.2.3.4" \
+	"cmddeny all 1.2.3.0/24" \
+	"cyclelogs" \
+	"delete 10.0.0.0" \
+	"delete ID#0000000001" \
+	"deny 1.2.3.4" \
+	"deny all 1.2.3.0/24" \
+	"dfreq 1.0e-3" \
+	"doffset -1.0" \
+	"dump" \
+	"local stratum 5 distance 1.0 orphan" \
+	"local off" \
+	"makestep 10.0 3" \
+	"makestep" \
+	"manual delete 0" \
+	"manual off" \
+	"manual on" \
+	"manual reset" \
+	"maxdelay 1.2.3.4 1e-2" \
+	"maxdelaydevratio 1.2.3.4 5.0" \
+	"maxdelayratio 1.2.3.4 3.0" \
+	"maxpoll 1.2.3.4 5" \
+	"maxupdateskew 1.2.3.4 10.0" \
+	"minpoll 1.2.3.4 3" \
+	"minstratum 1.2.3.4 1" \
+	"minstratum ID#0000000001 1" \
+	"ntpdata 1.2.3.4" \
+	"offline" \
+	"offline 255.255.255.0/1.2.3.0" \
+	"offline 1.2.3.0/24" \
+	"online" \
+	"online 1.2.3.0/24" \
+	"onoffline" \
+	"polltarget 1.2.3.4 10" \
+	"refresh" \
+	"rekey" \
+	"reload sources" \
+	"reselect" \
+	"reselectdist 1e-3" \
+	"reset sources" \
+	"selectdata" \
+	"settime 16:30" \
+	"settime 16:30:05" \
+	"settime Nov 21, 2015 16:30:05" \
+	"serverstats" \
+	"shutdown" \
+	"smoothtime reset" \
+	"smoothtime activate" \
+	"trimrtc" \
+	"writertc"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "501 Not authorised$" || test_fail
+done
+
+cmdmon_unix=1
+
+chronyc_conf="
+authdata
+clients -k -p 2
+clients -r
+clients
+ntpdata
+selectdata
+serverstats"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+node1\.net1\.clk                 -     0    0    0    -    0    0    0    0
+Hostname                      NTP   Drop Int IntL Last  NTS-KE   Drop Int  Last
+===============================================================================
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+node1\.net1\.clk                  1      0   -   -     0       0      0   -     -
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+node1\.net1\.clk                  0      0   -   -     0       0      0   -     -
+
+Remote address  : 192\.168\.123\.1 \(C0A87B01\)
+Remote port     : 123
+Local address   : 192\.168\.123\.1 \(C0A87B01\)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 6 \(64 seconds\)
+Precision       : -23 \(0\.000000119 seconds\)
+Root delay      : 0\.000000 seconds
+Root dispersion : 0\.000000 seconds
+Reference ID    : 7F7F0101 \(\)
+Reference time  : Thu Dec 31 23:59:5[89] 2009
+Offset          : [-+]0\.000...... seconds
+Peer delay      : 0\.00....... seconds
+Peer dispersion : 0\.00000.... seconds
+Response time   : 0\.000000... seconds
+Jitter asymmetry: \+0\.00
+NTP tests       : 111 111 1110
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 1
+Total RX        : 1
+Total valid RX  : 1
+Total good RX   : 0
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+M node1\.net1\.clk            N ----- -----    0   1\.0    \+0ns    \+0ns  N
+NTP packets received       : 1
+NTP packets dropped        : 0
+Command packets received   : 12
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 0
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 0
+Interleaved NTP packets    : 0
+NTP timestamps held        : 0
+NTP timestamp span         : 0$" || test_fail
+
+chronyc_conf="
+deny all
+cmdallow all
+allow 1.2.3.4
+allow 1.2.3.0/28
+deny 1.2.3.0/27
+allow 1.2.4.5
+deny all 1.2.4.0/27
+cmddeny 5.6.7.8
+cmdallow all 5.6.7.0/28
+accheck 1.2.3.4
+accheck 1.2.3.5
+accheck 1.2.4.5
+cmdaccheck 5.6.7.8"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+208 Access allowed
+209 Access denied
+209 Access denied
+208 Access allowed$" || test_fail
+
+if check_config_h 'FEAT_IPV6 1'; then
+	chronyc_conf="
+	deny all
+	cmdallow all
+	allow 2001:db8::1
+	allow 2001:db8::/64
+	deny 2001:db8::/63
+	allow 2001:db8:1::1
+	deny all 2001:db8:1::/63
+	cmddeny 2001:db9::1
+	cmdallow all 2001:db9::/64
+	accheck 2001:db8::1
+	accheck 2001:db8::2
+	accheck 2001:db8:1::1
+	cmdaccheck 2001:db9::1"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+
+	check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+208 Access allowed
+209 Access denied
+209 Access denied
+208 Access allowed$" || test_fail
+fi
+
+chronyc_conf="
+delete 192.168.123.1
+add server node1.net1.clk minpoll 6 maxpoll 10 iburst
+offline 192.168.123.1
+burst 1/1 192.168.123.1
+online 192.168.123.1
+maxdelay 192.168.123.1 1e-2
+maxdelaydevratio 192.168.123.1 5.0
+maxdelayratio 192.168.123.1 3.0
+maxpoll 192.168.123.1 5
+maxupdateskew 192.168.123.1 10.0
+minpoll 192.168.123.1 3
+minstratum 192.168.123.1 1
+polltarget 192.168.123.1 10
+delete 192.168.123.1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK$" || test_fail
+
+chronyc_conf="
+cyclelogs
+dump
+dfreq 1.0e-3
+doffset -0.01
+local stratum 5 distance 1.0 orphan
+local off
+makestep 10.0 3
+makestep
+manual on
+settime now
+manual delete 0
+manual reset
+manual off
+onoffline
+refresh
+rekey
+reload sources
+reselect
+reselectdist 1e-3
+reset sources
+shutdown"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+Clock was .\... seconds fast.  Frequency change = 0.00ppm, new frequency = 0.00ppm
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK$" || test_fail
+
+server_conf="
+server 192.168.123.1
+noclientlog"
+
+commands=(
+	"add server nosuchnode.net1.clk" "^Invalid host/IP address$"
+	"allow nosuchnode.net1.clk" "^Could not read address$"
+	"allow 192.168.123.0/2 4" "^Could not read address$"
+	"allow 192.168.123.0/2e" "^Could not read address$"
+	"allow 192.168.12e" "^Could not read address$"
+	"allow 192.168123" "^Could not read address$"
+	"allow 192.168.123.2/33" "^507 Bad subnet$"
+	"clients" "Hostname.*519 Client logging is not active in the daemon$"
+	"delete 192.168.123.2" "^503 No such source$"
+	"minpoll 192.168.123.2 5" "^503 No such source$"
+	"ntpdata 192.168.123.2" "^503 No such source$"
+	"settime now" "^505 Facility not enabled in daemon$"
+	"smoothing" "^505 Facility not enabled in daemon$"
+	"smoothtime activate" "^505 Facility not enabled in daemon$"
+	"smoothtime reset" "^505 Facility not enabled in daemon$"
+	"sourcename 192.168.123.2" "^503 No such source$"
+	"trimrtc" "^513 RTC driver not running$"
+	"writertc" "^513 RTC driver not running$"
+)
+
+for i in $(seq 0 $[${#commands[*]} / 2]); do
+	chronyc_conf=${commands[$[i * 2]]}
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "${commands[$[i * 2 + 1]]}" || test_fail
+done
+
+cmdmon_unix=0
+server_conf="server 192.168.123.1"
+
+chronyc_conf="dns -n
+dns +n
+dns -4
+dns -6
+dns -46
+timeout 200
+retries 1
+keygen
+keygen 10 MD5 128
+keygen 11 MD5 40
+help
+quit
+nosuchcommand"
+
+run_test || test_fail
+
+check_chronyc_output "^1 (MD5|SHA1) HEX:........................................
+10 MD5 HEX:................................
+11 MD5 HEX:....................
+System clock:.*this help
+ *$" || test_fail
+
+chronyc_conf="keygen 10 NOSUCHTYPE 128
+help"
+run_test || test_fail
+check_chronyc_output "^Unknown hash function or cipher NOSUCHTYPE\$" || test_fail
+
+if check_config_h 'FEAT_SECHASH 1'; then
+	for hash in MD5 SHA1 SHA256 SHA384 SHA512; do
+		chronyc_conf="keygen 5 $hash"
+		run_test || test_fail
+		check_chronyc_output "^5 $hash HEX:........................................\$" || test_fail
+	done
+fi
+
+if check_config_h 'HAVE_CMAC 1'; then
+	chronyc_conf="keygen 6 AES128
+keygen 7 AES256"
+	run_test || test_fail
+	check_chronyc_output "^6 AES128 HEX:................................
+7 AES256 HEX:................................................................\$" || test_fail
+fi
+
+# Pass every fourth request
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 (min (% (sum 1) 4) 1) 1)))
+EOF
+)
+limit=15
+
+chronyc_conf="sources"
+run_test || test_fail
+check_chronyc_output "^506 Cannot talk to daemon$" || test_fail
+
+chronyc_conf="retries 3
+sources"
+run_test || test_fail
+check_chronyc_output "^MS.*0ns$" || test_fail
+
+test_pass
diff --git a/test/simulation/111-knownclient b/test/simulation/111-knownclient
new file mode 100755
index 0000000..92bad54
--- /dev/null
+++ b/test/simulation/111-knownclient
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "reply to client configured as server"
+
+server_conf="server 192.168.123.2 noselect
+acquisitionport 123"
+client_conf="acquisitionport 123"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_port || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/112-port b/test/simulation/112-port
new file mode 100755
index 0000000..2f10eed
--- /dev/null
+++ b/test/simulation/112-port
@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "port and acquisitionport directives"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+# This check is expected to fail
+check_packet_port && test_fail
+
+client_conf="acquisitionport 123"
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_port || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_conf=""
+for server_conf in \
+	"port 0" \
+	"acquisitionport 123
+port 0"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_port || test_fail
+	check_packet_interval || test_fail
+	# These checks are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+server_conf="port 124
+acquisitionport 123"
+client_server_options="port 124"
+for client_conf in \
+	"acquisitionport 0" \
+	"acquisitionport 123" \
+	"acquisitionport 124"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	# This check is expected to fail
+	check_packet_port && test_fail
+done
+
+test_pass
diff --git a/test/simulation/113-leapsecond b/test/simulation/113-leapsecond
new file mode 100755
index 0000000..394440b
--- /dev/null
+++ b/test/simulation/113-leapsecond
@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "leap second"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Dec 30 2008 0:00:00' +'%s')
+
+leap=$[2 * 24 * 3600]
+limit=$[4 * 24 * 3600]
+client_start=$[2 * 3600]
+server_conf="refclock SHM 0 dpoll 10 poll 10
+leapsectz right/UTC"
+refclock_jitter=1e-9
+refclock_offset="(* -1.0 (equal 0.1 (max (sum 1.0) $leap) $leap))"
+
+for leapmode in system step slew; do
+	client_conf="leapsecmode $leapmode"
+	if [ $leapmode = slew ]; then
+		max_sync_time=$[$leap + 12]
+	else
+		max_sync_time=$[$leap]
+	fi
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+client_server_options="trust"
+client_conf="refclock SHM 0 dpoll 10 poll 10 delay 1e-3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_server_options=""
+client_conf="leapsecmode system"
+min_sync_time=230000
+max_sync_time=240000
+
+for smoothmode in "" "leaponly"; do
+	server_conf="refclock SHM 0 dpoll 10 poll 10
+	leapsectz right/UTC
+	leapsecmode slew
+	smoothtime 400 0.001 $smoothmode"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/114-presend b/test/simulation/114-presend
new file mode 100755
index 0000000..4fd89f8
--- /dev/null
+++ b/test/simulation/114-presend
@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "presend option"
+
+min_sync_time=136
+max_sync_time=260
+client_server_options="presend 6 maxdelay 16"
+client_conf="maxdistance 10"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+base_delay=5
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/115-cmdmontime b/test/simulation/115-cmdmontime
new file mode 100755
index 0000000..525062d
--- /dev/null
+++ b/test/simulation/115-cmdmontime
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "cmdmon timestamps"
+
+# The following tests need 64-bit time_t
+check_config_h 'HAVE_LONG_TIME_T 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=2
+client_server_options="noselect"
+client_conf="local stratum 1"
+chronyc_start="1.5"
+chronyc_conf="tracking"
+
+for year in `seq 1850 100 2300`; do
+	export CLKNETSIM_START_DATE=$(date -d "Jan 01 00:00:05 $year UTC" +'%s')
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "^.*Ref time \(UTC\).*Jan 01 00:00:0. $year.*$" || test_fail
+done
+
+test_pass
diff --git a/test/simulation/116-minsources b/test/simulation/116-minsources
new file mode 100755
index 0000000..f576423
--- /dev/null
+++ b/test/simulation/116-minsources
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "minsources directive"
+
+client_conf="minsources 3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+# These check are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+servers=3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/117-fallbackdrift b/test/simulation/117-fallbackdrift
new file mode 100755
index 0000000..21f6963
--- /dev/null
+++ b/test/simulation/117-fallbackdrift
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "fallback drift"
+
+limit=100000
+wander=0.0
+jitter=1e-6
+time_offset=10
+freq_offset="(* 1e-4 (sine 1000))"
+base_delay="(* -1.0 (equal 0.1 (min time 4250) 4250))"
+client_server_options="minpoll 4 maxpoll 4"
+client_conf="fallbackdrift 6 10"
+max_sync_time=4500
+time_max_limit=1e0
+time_rms_limit=1e0
+freq_max_limit=2e-4
+freq_rms_limit=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/118-maxdelay b/test/simulation/118-maxdelay
new file mode 100755
index 0000000..117b170
--- /dev/null
+++ b/test/simulation/118-maxdelay
@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "maxdelay options"
+
+max_sync_time=2000
+base_delay=1e-5
+jitter=1e-5
+wander=0.0
+freq_offset="(sum 1e-10)"
+time_rms_limit=2e-4
+
+client_server_options="maxpoll 6 maxdelay 3e-5 maxdelayratio 2.0 maxdelaydevratio 2.0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+for client_server_options in "maxpoll 6 maxdelay 2e-5"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync && test_fail
+done
+
+min_sync_time=10
+client_conf="
+logdir tmp
+log rawmeasurements"
+client_server_options="minpoll 2 maxpoll 2 maxdelayquant 0.1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 200 500 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1101" 2000 2300 measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/119-smoothtime b/test/simulation/119-smoothtime
new file mode 100755
index 0000000..7f5114c
--- /dev/null
+++ b/test/simulation/119-smoothtime
@@ -0,0 +1,82 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "smoothtime option"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+server_strata=2
+server_conf="smoothtime 400 0.001"
+server_server_options="minpoll 8"
+min_sync_time=600
+max_sync_time=800
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+limit=10000
+refclock_jitter=1e-4
+refclock_offset="(* 10.0 (equal 0.1 (max (sum 1.0) 1000) 1000))"
+server_step="(* -10.0 (equal 0.1 (sum 1.0) 1))"
+server_strata=1
+server_conf="refclock SHM 0 dpoll 4 poll 6
+smoothtime 2000 1
+maxjitter 10.0"
+time_offset=-10
+server_server_options=""
+client_server_options="minpoll 6 maxpoll 6"
+client_conf="corrtimeratio 100"
+min_sync_time=8000
+max_sync_time=9000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_options="minpoll 6 maxpoll 6 xleave maxdelay 1e-1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_options="minpoll 6 maxpoll 6"
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+time_max_limit=11
+time_rms_limit=11
+freq_max_limit=1e-2
+freq_rms_limit=2e-3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+refclock_jitter=1e-9
+refclock_offset="(* 1e-1 (triangle 1000) (+ -1.0 (pulse 1000 10000)))"
+server_step=""
+server_conf="refclock SHM 0 dpoll 4 poll 6 minsamples 4 maxsamples 4
+smoothtime 1e4 1e-6"
+client_server_options="minpoll 4 maxpoll 4"
+time_offset=0.1
+jitter=1e-6
+wander=0.0
+min_sync_time=30
+max_sync_time=40
+time_max_limit=1e-5
+time_rms_limit=5e-6
+freq_max_limit=1e-6
+freq_rms_limit=1e-7
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/120-selectoptions b/test/simulation/120-selectoptions
new file mode 100755
index 0000000..611815e
--- /dev/null
+++ b/test/simulation/120-selectoptions
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "source selection options"
+
+servers=3
+falsetickers=2
+
+base_delay=0.6
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 trust"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 prefer"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+# This check is expected to fail
+check_sync && test_fail
+
+base_delay=1.1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+base_delay=1e-3
+falsetickers=1
+
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 require"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_server_conf="
+server 192.168.123.1 require
+server 192.168.123.2
+server 192.168.123.3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+# These checks are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+cat > tmp/keys <<-EOF
+1 MD5 HEX:1B81CBF88D4A73F2E8CE59647F6E5C1719B6CAF5
+EOF
+
+server_conf="keyfile tmp/keys"
+client_server_conf="
+server 192.168.123.1 key 1
+server 192.168.123.2
+server 192.168.123.3"
+
+for authselectmode in require prefer mix ignore; do
+	client_conf="keyfile tmp/keys
+		     authselectmode $authselectmode"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	if [ $authselectmode = ignore ]; then
+		check_sync || test_fail
+	else
+		check_sync && test_fail
+	fi
+done
+
+test_pass
diff --git a/test/simulation/121-orphan b/test/simulation/121-orphan
new file mode 100755
index 0000000..7579997
--- /dev/null
+++ b/test/simulation/121-orphan
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "orphan option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+server_strata=3
+server_conf="local stratum 5 orphan
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3"
+max_sync_time=900
+client_start=140
+chronyc_start=700
+chronyc_conf="tracking"
+time_rms_limit=5e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^.*Stratum *: 7.*$" || test_fail
+
+test_pass
diff --git a/test/simulation/122-xleave b/test/simulation/122-xleave
new file mode 100755
index 0000000..c19063a
--- /dev/null
+++ b/test/simulation/122-xleave
@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "interleaved mode"
+
+client_server_options="xleave"
+client_conf="
+logdir tmp
+log rawmeasurements"
+
+server_conf="noclientlog"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 .111.* 4I [DKH] [DKH]\$" 0 0 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+server_conf=""
+max_sync_time=270
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 1111.* 4B [DKH] [DKH]\$" 2 2 measurements.log || test_fail
+check_file_messages "111 111 1111.* 4I [DKH] [DKH]\$" 30 200 measurements.log || test_fail
+check_file_messages "111 111 0111.* 4I [DKH] [DKH]\$" 1 1 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+clients=2
+peers=2
+max_sync_time=500
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 2) (equal 0.1 to 1)))"
+
+client_lpeer_options="xleave minpoll 5 maxpoll 5"
+client_rpeer_options="minpoll 5 maxpoll 5"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# These checks are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+rm -f tmp/measurements.log
+
+for rpoll in 4 5 6; do
+	client_rpeer_options="xleave minpoll $rpoll maxpoll $rpoll"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	if [ $rpoll -le 5 ]; then
+		check_file_messages "111 111 1111.* 1B [DKH] [DKH]\$" 0 0 measurements.log || test_fail
+		check_file_messages "111 111 1111.* 1I [DKH] [DKH]\$" 200 310 measurements.log || test_fail
+	else
+		check_file_messages "111 111 1111.* 1B [DKH] [DKH]\$" 125 135 measurements.log || test_fail
+		check_file_messages "111 111 1111.* 1I [DKH] [DKH]\$" 20 30 measurements.log || test_fail
+	fi
+	rm -f tmp/measurements.log
+done
+
+if check_config_h 'FEAT_CMDMON 1'; then
+	# test client timestamp selection and server timestamp correction
+	base_delay="(+ 1.25e-6 (* -1 (equal 0.1 from 5)))"
+	jitter=1e-9
+	wander=1e-12
+	client_lpeer_options="xleave minpoll 5 maxpoll 5 noselect"
+	client_rpeer_options="xleave minpoll 5 maxpoll 5 noselect"
+	chronyc_conf="doffset -0.1"
+	chronyc_start=7200
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync && test_fail
+
+	check_file_messages "\.2   N  2 111 111 ....   5  5 .\... ..\....e-..  2\....e-06" \
+		290 310 measurements.log || test_fail
+	check_file_messages "\.2   N  2 111 111 ....   5  5 .\... ..\....e-..  .\....e-0[0123]" \
+		0 0 measurements.log || test_fail
+	rm -f tmp/measurements.log
+fi
+
+test_pass
diff --git a/test/simulation/123-mindelay b/test/simulation/123-mindelay
new file mode 100755
index 0000000..89a9f33
--- /dev/null
+++ b/test/simulation/123-mindelay
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "mindelay and asymmetry options"
+
+jitter_asymmetry=0.499
+time_rms_limit=1e-6
+time_freq_limit=1e-9
+wander=1e-12
+
+for client_server_options in "mindelay 2e-4 asymmetry 0.499"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+for client_server_options in "mindelay 1e-4 asymmetry 0.499" "mindelay 2e-4 asymmetry 0.0"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync && test_fail
+done
+
+test_pass
diff --git a/test/simulation/124-tai b/test/simulation/124-tai
new file mode 100755
index 0000000..97064f7
--- /dev/null
+++ b/test/simulation/124-tai
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "tai option"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Dec 31 2008 23:50:00' +'%s')
+
+leap=$[10 * 60]
+limit=$[20 * 60]
+min_sync_time=2
+max_sync_time=15
+refclock_jitter=1e-6
+servers=0
+
+refclock_offset="(+ -34 (equal 0.1 (max (sum 1.0) $leap) $leap))"
+client_conf="
+refclock SHM 0 dpoll 0 poll 0 tai
+leapsectz right/UTC
+leapsecmode ignore
+maxchange 1e-3 1 0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Jan 01 2009 00:10:00' +'%s')
+
+time_offset=-1000
+refclock_offset="(+ -34)"
+client_conf="
+refclock SHM 0 dpoll 0 poll 0 tai
+leapsectz right/UTC
+makestep 1 1
+maxchange 1e-3 1 0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/125-packetloss b/test/simulation/125-packetloss
new file mode 100755
index 0000000..505e4fa
--- /dev/null
+++ b/test/simulation/125-packetloss
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "packet loss"
+
+# Drop 33% of packets by default and 100% on the 3->1 path
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1 (equal 0.33 (uniform) 1.0))
+     (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))
+EOF
+)
+clients=2
+peers=2
+jitter=1e-5
+limit=20000
+max_sync_time=10000
+
+for options in "maxpoll 8" "maxpoll 8 xleave"; do
+	client_server_options=$options
+	client_peer_options=$options
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/126-burst b/test/simulation/126-burst
new file mode 100755
index 0000000..1cb6f9c
--- /dev/null
+++ b/test/simulation/126-burst
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "burst option"
+
+# Pass every fourth packet on the 2->1 path
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (% (sum 1) 4) 1) 1)))
+EOF
+)
+
+client_server_options="burst polltarget 1"
+min_sync_time=700
+max_sync_time=730
+client_max_min_out_interval=2.2
+client_min_mean_out_interval=150.0
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+# Add a significant delay to 70% of packets on the 2->1 path after 6th packet
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* 0.15
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (sum 1) 7) 7)
+        (equal 0.7 (uniform) 0.0)))
+EOF
+)
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+
+test_pass
diff --git a/test/simulation/127-filter b/test/simulation/127-filter
new file mode 100755
index 0000000..739dd91
--- /dev/null
+++ b/test/simulation/127-filter
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "filter option"
+
+client_server_options="minpoll 4 maxpoll 4 filter 15 maxdelay 3.5e-4"
+min_sync_time=710
+max_sync_time=720
+client_max_min_out_interval=16.1
+client_min_mean_out_interval=15.9
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+base_delay="(+ 1e-4 (* -1 (equal 0.3 (uniform) 0.0)))"
+client_server_options="minpoll 4 maxpoll 4 filter 3"
+min_sync_time=130
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+limit=10
+client_server_options="minpoll -6 maxpoll -6 filter 1"
+
+base_delay=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_file_messages "	2	1	" 590 640 log.packets || test_fail
+
+base_delay=2e-2
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_file_messages "	2	1	" 9 10 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/128-nocontrol b/test/simulation/128-nocontrol
new file mode 100755
index 0000000..3f0d18d
--- /dev/null
+++ b/test/simulation/128-nocontrol
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-x option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+wander=0.0
+time_offset=0.0
+freq_offset=0.0
+time_max_limit=1e-6
+freq_max_limit=1e-9
+min_sync_time=0
+max_sync_time=0
+client_chronyd_options="-x"
+chronyc_start=300
+chronyc_conf="tracking"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_chronyc_output "^.*Stratum *: 2.*$" || test_fail
+
+test_pass
diff --git a/test/simulation/129-reload b/test/simulation/129-reload
new file mode 100755
index 0000000..56bc3da
--- /dev/null
+++ b/test/simulation/129-reload
@@ -0,0 +1,109 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-r option"
+
+wander=0.0
+limit=100
+min_sync_time=100
+max_sync_time=104
+client_chronyd_options="-r"
+client_conf="dumpdir tmp
+maxupdateskew 10000"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_log_messages "Loaded dump file" 0 0 || test_fail
+check_file_messages "." 6 6 192.168.123.1.dat || test_fail
+
+client_start=$limit
+limit=1000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Loaded dump file" 1 1 || test_fail
+check_file_messages "." 10 30 192.168.123.1.dat || test_fail
+
+rm -f tmp/*.dat
+
+client_start=0
+limit=200
+jitter=1e-6
+client_conf="dumpdir tmp
+maxupdateskew 1e-6
+maxslewrate 1e-6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_log_messages "Loaded dump file" 0 0 || test_fail
+check_file_messages "." 8 8 192.168.123.1.dat || test_fail
+cp tmp/192.168.123.1.dat tmp/backup.dat
+
+client_start=$limit
+limit=1000
+min_sync_time=201
+max_sync_time=203
+client_server_options="offline"
+client_conf="dumpdir tmp"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Loaded dump file" 1 1 || test_fail
+check_file_messages "." 8 8 192.168.123.1.dat || test_fail
+
+cp -f tmp/backup.dat tmp/192.168.123.1.dat
+
+client_server_options="key 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync && test_fail
+
+check_log_messages "Could not load dump file" 1 1 || test_fail
+check_log_messages "Loaded dump file" 0 0 || test_fail
+
+client_server_options=""
+
+if check_config_h 'FEAT_REFCLOCK 1'; then
+	refclock_jitter=1e-6
+	servers=0
+	client_start=0
+	limit=40
+	min_sync_time=56
+	max_sync_time=58
+	client_chronyd_options="-r"
+	client_conf="dumpdir tmp
+	refclock SHM 0"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+
+	check_log_messages "Loaded dump file" 0 0 || test_fail
+	check_file_messages "." 6 6 refid:53484d30.dat || test_fail
+
+	client_start=$limit
+	limit=300
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_log_messages "Loaded dump file" 1 1 || test_fail
+	check_file_messages "." 6 23 refid:53484d30.dat || test_fail
+
+	rm -f tmp/*.dat
+fi
+
+test_pass
diff --git a/test/simulation/130-quit b/test/simulation/130-quit
new file mode 100755
index 0000000..da2b8cf
--- /dev/null
+++ b/test/simulation/130-quit
@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-q/-Q option"
+
+wander=0.0
+freq_offset=0.0
+min_sync_time=5
+max_sync_time=10
+client_chronyd_options="-q"
+client_server_options="iburst"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+min_sync_time=1
+max_sync_time=1
+client_server_options="iburst maxsamples 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+client_chronyd_options="-Q"
+run_test || test_fail
+check_sync && test_fail
+
+test_pass
diff --git a/test/simulation/131-maxchange b/test/simulation/131-maxchange
new file mode 100755
index 0000000..59cc0c1
--- /dev/null
+++ b/test/simulation/131-maxchange
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "maxchange directive"
+
+time_offset=2
+max_sync_time=5000
+client_conf="maxchange 0.1 1 3"
+client_step="(* $step (equal 0.1 (sum 1.0) 300))"
+
+run_test || test_fail
+check_chronyd_exit && test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync && test_fail
+check_log_messages "seconds exceeds.*ignored" 3 3 || test_fail
+check_log_messages "seconds exceeds.*exiting" 1 1 || test_fail
+
+test_pass
diff --git a/test/simulation/132-logchange b/test/simulation/132-logchange
new file mode 100755
index 0000000..59ddf7c
--- /dev/null
+++ b/test/simulation/132-logchange
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "logchange directive"
+
+time_offset=2
+min_sync_time=590
+max_sync_time=700
+client_server_options="maxsamples 6"
+client_conf="logchange 0.1"
+client_step="(* $step (equal 0.1 (sum 1.0) 300))"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_log_messages "clock wrong by" 4 8 || test_fail
+
+test_pass
diff --git a/test/simulation/133-hwtimestamp b/test/simulation/133-hwtimestamp
new file mode 100755
index 0000000..d3cce6d
--- /dev/null
+++ b/test/simulation/133-hwtimestamp
@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "hwtimestamp directive"
+
+check_config_h 'HAVE_LINUX_TIMESTAMPING 1' || test_skip
+
+export CLKNETSIM_TIMESTAMPING=2
+export CLKNETSIM_PHC_DELAY=1e-6
+export CLKNETSIM_PHC_JITTER=1e-7
+export CLKNETSIM_PHC_JITTER_ASYM=0.4
+
+refclock_jitter=1e-8
+refclock_offset=10.0
+min_sync_time=4
+max_sync_time=20
+time_rms_limit=1e-7
+freq_rms_limit=3e-8
+jitter=1e-8
+freq_offset=1e-5
+limit=200
+server_conf="
+clockprecision 1e-9
+hwtimestamp eth0"
+client_server_options="minpoll 0 maxpoll 0 xleave"
+client_chronyd_options="-d"
+
+for client_conf in \
+		"hwtimestamp eth0 nocrossts
+		clockprecision 1e-9" \
+		"hwtimestamp eth0
+		clockprecision 1e-9
+		acquisitionport 123"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	if check_config_h 'FEAT_DEBUG 1'; then
+		check_log_messages "Accepted reading" 0 2 || test_fail
+		check_log_messages "Combined .* readings" 190 220 || test_fail
+		check_log_messages "HW clock samples" 190 200 || test_fail
+		check_log_messages "HW clock reset" 0 0 || test_fail
+		check_log_messages "Missing TX timestamp" 1 1 || test_fail
+		check_log_messages "Received message.*tss=KH" 195 200 || test_fail
+		check_log_messages "Received error.*message.*tss=KH" 195 200 || test_fail
+		check_log_messages "Updated RX timestamp.*tss=1" 1 1 || test_fail
+		check_log_messages "Updated RX timestamp.*tss=2" 195 200 || test_fail
+		if echo "$client_conf" | grep -q nocrossts; then
+			check_log_messages "update_tx_timestamp.*Updated" 180 200 || test_fail
+			check_log_messages "update_tx_timestamp.*Unacceptable" 0 10 || test_fail
+		else
+			check_log_messages "update_tx_timestamp.*Updated" 50 140 || test_fail
+			check_log_messages "update_tx_timestamp.*Unacceptable" 50 140 || test_fail
+		fi
+	fi
+done
+
+test_pass
diff --git a/test/simulation/134-log b/test/simulation/134-log
new file mode 100755
index 0000000..ab1ced2
--- /dev/null
+++ b/test/simulation/134-log
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "log directive"
+
+check_config_h 'FEAT_PHC 1' || test_skip
+
+refclock_jitter=$jitter
+client_server_options="maxpoll 6"
+client_conf="refclock PHC /dev/ptp0 dpoll 4 poll 6 noselect
+logbanner 10
+logdir tmp
+log tracking rawmeasurements measurements selection statistics rtc refclocks tempcomp
+tempcomp tmp/tempcomp 64 0.0 0.0 0.0 0.0"
+
+echo 0.0 > tmp/tempcomp
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "=============" 31 33 \
+	tracking.log measurements.log tempcomp.log || test_fail
+check_file_messages "20.*192\.168\.123\.1" 150 160 \
+	tracking.log measurements.log statistics.log || test_fail
+check_file_messages "20.*PHC0 * N " 300 320 selection.log || test_fail
+check_file_messages "20.*192\.168\.123\.1 *[M*]" 300 320 selection.log || test_fail
+check_file_messages "20.*PHC0" 150 160 statistics.log || test_fail
+check_file_messages "20.*PHC0" 750 800 refclocks.log || test_fail
+check_file_messages "20.* 0\.0000" 150 160 tempcomp.log || test_fail
+
+test_pass
diff --git a/test/simulation/135-ratelimit b/test/simulation/135-ratelimit
new file mode 100755
index 0000000..86c435d
--- /dev/null
+++ b/test/simulation/135-ratelimit
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "ratelimit directive"
+
+server_conf="ratelimit interval 6 burst 2 leak 4"
+client_server_options="minpoll 3 maxpoll 3"
+min_sync_time=16
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "	2	1	" 1200 1300 log.packets || test_fail
+check_file_messages "	1	2	" 180 220 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/136-broadcast b/test/simulation/136-broadcast
new file mode 100755
index 0000000..1488c53
--- /dev/null
+++ b/test/simulation/136-broadcast
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "broadcast directive"
+
+server_conf="broadcast 64 192.168.123.255"
+client_server_options="offline"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval && test_fail
+
+check_file_messages "	1	2	" 150 160 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/137-pool b/test/simulation/137-pool
new file mode 100755
index 0000000..de8d77d
--- /dev/null
+++ b/test/simulation/137-pool
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "pool directive"
+
+limit=500
+client_conf="logdir tmp
+log measurements"
+
+servers=3
+client_server_conf="pool nodes-1-2-3.net1.clk"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.1" 5 10 measurements.log || test_fail
+check_file_messages "20.*192.168.123.2" 5 10 measurements.log || test_fail
+check_file_messages "20.*192.168.123.3" 5 10 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+servers=6
+client_server_conf="pool nodes-1-2-3-4-5-6.net1.clk minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.*" 30 35 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+servers=6
+client_server_conf="pool nodes-1-2-3-4-5-6.net1.clk maxsources 2 minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.*" 15 17 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+test_pass
diff --git a/test/simulation/138-syncloop b/test/simulation/138-syncloop
new file mode 100755
index 0000000..2d3999e
--- /dev/null
+++ b/test/simulation/138-syncloop
@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "loop prevention"
+
+mkdir tmp/logdir1 tmp/logdir2
+
+server_conf="
+server 192.168.123.1
+server 192.168.123.2
+logdir tmp/logdir1
+log measurements"
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+logdir tmp/logdir2
+log measurements
+allow"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1110" 30 200 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1110" 30 200 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\...* 111 111 1111" 0 0 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1111" 30 200 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1110" 0 0 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1110" 30 200 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1111" 0 0 logdir1/measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/139-nts b/test/simulation/139-nts
new file mode 100755
index 0000000..6a2112d
--- /dev/null
+++ b/test/simulation/139-nts
@@ -0,0 +1,312 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP authentication with NTS"
+
+check_config_h 'FEAT_NTS 1' || test_skip
+certtool --help &> /dev/null || test_skip
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010' +'%s')
+
+for i in 1 2; do
+	cat > tmp/cert$i.cfg <<-EOF
+	cn = "node$i.net1.clk"
+	dns_name = "node$i.net1.clk"
+	ip_address = "192.168.123.$i"
+	serial = 001
+	activation_date = "2010-01-01 00:00:00 UTC"
+	expiration_date = "2010-01-02 00:00:00 UTC"
+	signing_key
+	encryption_key
+	EOF
+
+	certtool --generate-privkey --key-type=ed25519 --outfile tmp/server$i.key &> \
+		tmp/log.certtool$i
+	certtool --generate-self-signed --load-privkey tmp/server$i.key \
+		--template tmp/cert$i.cfg --outfile tmp/server$i.crt &>> tmp/log.certtool$i
+done
+
+max_sync_time=400
+dns=1
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 66
+ntsdumpdir tmp
+"
+client_server_options="minpoll 6 maxpoll 6 nts"
+client_conf="
+nosystemcert
+ntstrustedcerts /dev/null
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts /dev/null
+logdir tmp
+log rawmeasurements"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 75 80 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 37 39 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 260 300 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+rm -f tmp/measurements.log
+
+client_conf+="
+ntsrefresh 120
+ntsdumpdir tmp"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 99 103 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 0 0 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 350 390 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+check_file_messages "." 12 13 192.168.123.1.nts || test_fail
+rm -f tmp/measurements.log
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010 + 40000 sec' +'%s')
+
+server_conf+="
+ntsrotate 100000"
+client_conf+="
+ntsrefresh 39500"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 150 160 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 0 0 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 6 10 log.packets || test_fail
+check_file_messages "^9\.......e+03	2	1	.*	4460	" 6 10 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+check_file_messages "." 12 13 192.168.123.1.nts || test_fail
+rm -f tmp/measurements.log
+
+client_conf="
+nosystemcert"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	2	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	2	1	.*	4460	" 10 20 log.packets || test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  2 00:00:01 UTC 2010' +'%s')
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	2	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	2	1	.*	4460	" 10 20 log.packets || test_fail
+check_log_messages "expired certificate" 4 4 || test_fail
+
+client_conf+="
+nocerttimecheck 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010' +'%s')
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntsrefresh 500"
+
+for dns in 1 0; do
+	server_conf="
+	ntsserverkey tmp/server1.key
+	ntsservercert tmp/server1.crt
+	ntsprocesses 0
+	ntsrotate 0
+	ntsdumpdir tmp"
+
+	if [ $dns != 0 ]; then
+		server_conf+="
+		ntsntpserver node2.net1.clk"
+		client_server_conf="server node1.net1.clk $client_server_options"
+	else
+		server_conf+="
+		ntsntpserver 192.168.123.2"
+		client_server_conf="server 192.168.123.1 $client_server_options"
+	fi
+
+	servers=1
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+
+	check_file_messages "	2	1	.*	4460	" 50 100 log.packets || test_fail
+	check_file_messages "	2	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 6 8 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 6 8 || test_fail
+
+	servers=2
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_file_messages "	3	1	.*	4460	" 100 150 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 1 1 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 0 0 || test_fail
+
+	server_conf+="
+	ntsratelimit interval 12 burst 1 leak 4"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection && test_fail
+
+	check_file_messages "	3	1	.*	4460	1	0	2" 25 50 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 2 6 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 1 6 || test_fail
+done
+
+servers=2
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 0
+ntsntpserver node2.net1.clk
+port 11123
+ntsdumpdir tmp"
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntsdumpdir tmp"
+client_server_conf="server 192.168.123.1 $client_server_options"
+
+rm -f tmp/*.nts
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_log_messages "Could not change" 0 0 || test_fail
+check_file_messages "	3	1	.*	4460	1	0	2" 1 1 log.packets || test_fail
+check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+
+for dns in 1 0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_log_messages "Could not change" 0 0 || test_fail
+	check_file_messages "	3	1	.*	4460	1	0	2" 0 0 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+done
+
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 0
+ntsdumpdir tmp"
+
+head -n 8 tmp/192.168.123.1.nts > tmp/192.168.123.1.nts_
+mv tmp/192.168.123.1.nts_ tmp/192.168.123.1.nts
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_log_messages "Could not change" 0 0 || test_fail
+check_file_messages "	3	1	.*	4460	1	0	2" 1 1 log.packets || test_fail
+check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+check_file_messages "	3	1	.*	11123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	11123	" 3 3 log.packets || test_fail
+
+dns=1
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsserverkey tmp/server2.key
+ntsservercert tmp/server2.crt
+ntsprocesses 0"
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts tmp/server2.crt
+minsources 2"
+client_server_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts 1 tmp/server1.crt
+ntstrustedcerts 2 tmp/server2.crt
+ntstrustedcerts 3 tmp/server2.crt"
+client_server_conf="
+server node1.net1.clk $client_server_options certset 0
+server node2.net1.clk $client_server_options certset 2"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "	3	1	.*	123	" 100 200 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 100 200 log.packets || test_fail
+
+client_server_conf="
+server node1.net1.clk $client_server_options certset 2
+server node2.net1.clk $client_server_options"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	3	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/nosuch.crt
+ntstrustedcerts 2 tmp/nosuch.crt"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	3	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/140-noclientlog b/test/simulation/140-noclientlog
new file mode 100755
index 0000000..502398f
--- /dev/null
+++ b/test/simulation/140-noclientlog
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "noclientlog option"
+
+server_conf="noclientlog"
+client_server_options="xleave"
+client_conf="
+logdir tmp
+log rawmeasurements"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 1111.* 4B " 30 200 measurements.log || test_fail
+check_file_messages "111 111 1111.* 4I " 0 0 measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/141-copy b/test/simulation/141-copy
new file mode 100755
index 0000000..80e56bc
--- /dev/null
+++ b/test/simulation/141-copy
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "copy option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+client_server_options="copy"
+chronyc_conf="tracking"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^Reference ID *: 7F7F0101 \(192\.168\.123\.1\)
+Stratum *: 1" || test_fail
+
+test_pass
diff --git a/test/simulation/142-ptpport b/test/simulation/142-ptpport
new file mode 100755
index 0000000..060932c
--- /dev/null
+++ b/test/simulation/142-ptpport
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "PTP port"
+
+# Block communication between 3 and 1
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))"
+
+cat > tmp/peer.keys <<-EOF
+1 MD5 1234567890
+EOF
+
+clients=2
+peers=2
+max_sync_time=420
+
+server_conf="
+ptpport 319"
+client_conf="
+ptpport 319
+authselectmode ignore
+keyfile tmp/peer.keys"
+client_server_options="minpoll 6 maxpoll 6 port 319"
+client_peer_options="minpoll 6 maxpoll 6 port 319 key 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "	2	1	.*	319	319	1	96	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	1	2	.*	319	319	1	96	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	2	3	.*	319	319	1	116	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	3	2	.*	319	319	1	116	" 150 160 \
+	log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/143-manual b/test/simulation/143-manual
new file mode 100755
index 0000000..618cee6
--- /dev/null
+++ b/test/simulation/143-manual
@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+export TZ=UTC
+
+test_start "manual input"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=$[12 * 3600]
+client_server_conf=" "
+client_conf="manual"
+chronyc_conf="timeout 4000000
+settime 1:00:00
+settime 2:00:00
+settime 3:00:00
+settime 4:00:00
+manual delete 2
+settime 6:00:00
+manual list
+settime 8:00:00
+manual reset
+settime 10:00:00
+manual list"
+chronyc_start=1800
+base_delay=1800
+jitter=1e-6
+
+time_max_limit=4e-3
+freq_max_limit=4e-3
+time_rms_limit=2e-3
+freq_rms_limit=2e-5
+min_sync_time=7204
+max_sync_time=7206
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+check_chronyc_output "^200 OK
+Clock was 0\.4. seconds fast\.  Frequency change = 0\.00ppm, new frequency = 0\.00ppm
+200 OK
+Clock was 0\.3. seconds fast\.  Frequency change = (99|100)\...ppm, new frequency = (99|100)\...ppm
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[01].ppm, new frequency = (99|100)\...ppm
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[01].ppm, new frequency = (99|100)\...ppm
+200 OK
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[012].ppm, new frequency = (99|100)\...ppm
+210 n_samples = 4
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0 2010-01-01 (00:59:59|01:00:00)      [- ]0\.00       0\.46      [- ]0\.00
+ 1 2010-01-01 (01:59:59|02:00:00)      [- ]0\.00       0\.36      [- ]0\.00
+ 2 2010-01-01 (03:59:59|04:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00
+ 3 2010-01-01 (05:59:59|06:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[012].ppm, new frequency = (99|100)\...ppm
+200 OK
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.00ppm, new frequency = (99|100)\...ppm
+210 n_samples = 1
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0 2010-01-01 (09:59:59|10:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00$" \
+	|| test_fail
+
+test_pass
diff --git a/test/simulation/144-exp1 b/test/simulation/144-exp1
new file mode 100755
index 0000000..4a2042d
--- /dev/null
+++ b/test/simulation/144-exp1
@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "experimental extension field"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+primary_time_offset=0.1
+server_strata=4
+min_sync_time=2000
+max_sync_time=2300
+chronyc_conf="doffset 0.1"
+chronyc_options="-h /clknetsim/unix/1:1"
+chronyc_start=2000
+
+for options in "extfield F323" "xleave extfield F323"; do
+	client_server_options="minpoll 6 maxpoll 6 $options"
+	server_server_options="$client_server_options"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+done
+
+server_server_options=""
+server_strata=1
+clients=4
+peers=4
+max_sync_time=2400
+# chain of peers and one enabled chronyc
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4 -1
+     (equal 0.1 from (+ to 1))
+     (equal 0.1 from (+ to -1))
+     (equal 0.1 from 6)
+     (equal 0.1 to 6))
+EOF
+)
+
+for lpoll in 5 6 7; do
+	for options in "minsamples 16 extfield F323" "minsamples 16 xleave extfield F323"; do
+		client_lpeer_options="minpoll $lpoll maxpoll $lpoll $options"
+		client_rpeer_options="minpoll 6 maxpoll 6 $options"
+		client_server_options="$client_rpeer_options"
+
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_sync || test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/201-freqaccumulation b/test/simulation/201-freqaccumulation
new file mode 100755
index 0000000..6f14246
--- /dev/null
+++ b/test/simulation/201-freqaccumulation
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+# Test fix in commit 60d0fa299307076143da94d36deb7b908fa9bdb7
+
+test_start "frequency accumulation"
+
+time_offset=100.0
+jitter=1e-6
+base_delay=1e-6
+wander=0.0
+
+limit=180
+time_max_limit=1e-5
+freq_max_limit=1e-7
+time_rms_limit=1e-5
+freq_rms_limit=1e-7
+min_sync_time=120
+max_sync_time=140
+
+client_server_options="minpoll 6 maxpoll 6"
+client_conf="driftfile tmp/drift
+makestep 1 1"
+
+for freq_offset in -5e-2 -5e-4 5e-4 5e-2; do
+	for drift in -1e+4 -1e+2 1e+2 1e+4; do
+		echo "$drift 100000" > tmp/drift
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_sync || test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/202-prefer b/test/simulation/202-prefer
new file mode 100755
index 0000000..207c800
--- /dev/null
+++ b/test/simulation/202-prefer
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+# Test fix in commit 4253075a97141edfa62043ab71bd0673587e6629
+
+test_start "prefer option"
+
+servers=3
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 prefer"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/README b/test/simulation/README
new file mode 100644
index 0000000..e174500
--- /dev/null
+++ b/test/simulation/README
@@ -0,0 +1,11 @@
+This is a collection of simulation tests using the clknetsim simulator
+(supported on Linux only).
+
+https://github.com/mlichvar/clknetsim
+
+The CLKNETSIM_PATH environment variable should point to the directory where
+clknetsim was downloaded and compiled. If the variable is not set, the tests
+will look for clknetsim in ./clknetsim in the current directory.
+
+The tests are written in bash and they can be run directly. The ./run script
+runs all tests.
diff --git a/test/simulation/run b/test/simulation/run
new file mode 100755
index 0000000..0954438
--- /dev/null
+++ b/test/simulation/run
@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+
+print_help() {
+	echo "$1 [-a] [-i ITERATIONS] [-m MAXFAILS] [-s SEED] [TEST]..."
+}
+
+run_test() {
+	local result name=$1 seed=$2
+
+	CLKNETSIM_RANDOM_SEED=$seed ./$name
+	result=$?
+
+	if [ $result -ne 0 -a $result -ne 9 ]; then
+		if [ $abort_on_fail -ne 0 ]; then
+			echo 1>&2
+			echo Failed with random seed $seed 1>&2
+			exit 1
+		fi
+		failed_seeds=(${failed_seeds[@]} $seed)
+	fi
+
+	return $result
+}
+
+abort_on_fail=0
+iterations=1
+max_fails=0
+random_seed=${CLKNETSIM_RANDOM_SEED:-$RANDOM}
+
+while getopts ":ai:m:s:" opt; do
+	case $opt in
+		a) abort_on_fail=1;;
+		i) iterations=$OPTARG;;
+		m) max_fails=$OPTARG;;
+		s) random_seed=$OPTARG;;
+		*) print_help "$0"; exit 3;;
+	esac
+done
+
+shift $[$OPTIND - 1]
+
+passed=() failed=() skipped=() failed_seeds=()
+
+[ $# -gt 0 ] && tests=($@) || tests=([0-9]*-*[^_])
+
+for test in "${tests[@]}"; do
+	if [ $iterations -gt 1 ]; then
+		printf "%-30s" "$test"
+		fails=0
+		for i in $(seq 1 $iterations); do
+			run_test $test $[$random_seed + $i - 1] > /dev/null
+			case $? in
+				0) echo -n ".";;
+				9) break;;
+				*) echo -n "x"; fails=$[$fails + 1];;
+			esac
+		done
+		if [ $i -lt $iterations ]; then
+			printf "%${iterations}s" ""
+			echo " SKIP"
+			result=9
+		elif [ $fails -gt $max_fails ]; then
+			echo " FAIL"
+			result=1
+		else
+			echo " PASS"
+			result=0
+		fi
+	else
+		printf "%s   " "$test"
+		run_test $test $random_seed
+		result=$?
+		echo
+	fi
+
+	case $result in
+		0) passed=(${passed[@]} $test);;
+		9) skipped=(${skipped[@]} $test);;
+		*) failed=(${failed[@]} $test);;
+	esac
+done
+
+echo
+echo "SUMMARY:"
+echo "  TOTAL  $[${#passed[@]} + ${#failed[@]} + ${#skipped[@]}]"
+echo "  PASSED ${#passed[@]}"
+echo "  FAILED ${#failed[@]}    (${failed[@]}) (${failed_seeds[@]})"
+echo "  SKIPPED ${#skipped[@]}   (${skipped[@]})"
+
+[ ${#failed[@]} -eq 0 ]
diff --git a/test/simulation/test.common b/test/simulation/test.common
new file mode 100644
index 0000000..70bbde1
--- /dev/null
+++ b/test/simulation/test.common
@@ -0,0 +1,528 @@
+# Copyright (C) 2013-2014  Miroslav Lichvar <mlichvar@redhat.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+export LC_ALL=C
+export PATH=../../:$PATH
+export CLKNETSIM_PATH=${CLKNETSIM_PATH:-clknetsim}
+
+if [ ! -x $CLKNETSIM_PATH/clknetsim ]; then
+	echo "SKIP (clknetsim not found)"
+	exit 9
+fi
+
+. $CLKNETSIM_PATH/clknetsim.bash
+
+# Default test testings
+
+default_limit=10000
+default_primary_time_offset=0.0
+default_time_offset=1e-1
+default_freq_offset=1e-4
+default_base_delay=1e-4
+default_jitter=1e-4
+default_jitter_asymmetry=0.0
+default_wander=1e-9
+default_refclock_jitter=""
+default_refclock_offset=0.0
+
+default_update_interval=0
+default_shift_pll=2
+
+default_server_strata=1
+default_servers=1
+default_clients=1
+default_peers=0
+default_falsetickers=0
+default_server_start=0.0
+default_client_start=0.0
+default_chronyc_start=1000.0
+default_server_step=""
+default_client_step=""
+
+default_client_server_conf=""
+default_server_server_options=""
+default_client_server_options=""
+default_server_peer_options=""
+default_server_lpeer_options=""
+default_server_rpeer_options=""
+default_client_peer_options=""
+default_client_lpeer_options=""
+default_client_rpeer_options=""
+default_server_conf=""
+default_client_conf=""
+default_chronyc_conf=""
+default_server_chronyd_options=""
+default_client_chronyd_options=""
+default_chronyc_options=""
+
+default_time_max_limit=1e-3
+default_freq_max_limit=5e-4
+default_time_rms_limit=3e-4
+default_freq_rms_limit=1e-5
+default_min_sync_time=120
+default_max_sync_time=210
+
+default_client_min_mean_out_interval=0.0
+default_client_max_min_out_interval=inf
+
+default_cmdmon_unix=1
+default_dns=0
+
+# Initialize test settings from their defaults
+for defoptname in ${!default_*}; do
+	optname=${defoptname#default_}
+	[ -z "${!optname}" ] && declare "$optname"="${!defoptname}"
+done
+
+test_start() {
+	rm -rf tmp/*
+	echo "Testing $@:"
+
+	check_config_h 'FEAT_NTP 1' || test_skip
+}
+
+test_pass() {
+	echo "PASS"
+	exit 0
+}
+
+test_fail() {
+	echo "FAIL"
+	exit 1
+}
+
+test_skip() {
+	echo "SKIP"
+	exit 9
+}
+
+test_ok() {
+	pad_line
+	echo -e "\tOK"
+	return 0
+}
+
+test_bad() {
+	pad_line
+	echo -e "\tBAD"
+	return 1
+}
+
+test_error() {
+	pad_line
+	echo -e "\tERROR"
+	return 1
+}
+
+msg_length=0
+pad_line() {
+	local line_length=56
+	[ $msg_length -lt $line_length ] && \
+		printf "%$[$line_length - $msg_length]s" ""
+	msg_length=0
+}
+
+# Print aligned message
+test_message() {
+	local level=$1 eol=$2
+	shift 2
+	local msg="$*"
+
+	while [ $level -gt 0 ]; do
+		echo -n "  "
+		level=$[$level - 1]
+		msg_length=$[$msg_length + 2]
+	done
+	echo -n "$msg"
+
+	msg_length=$[$msg_length + ${#msg}]
+	if [ $eol -ne 0 ]; then
+		echo
+		msg_length=0
+	fi
+}
+
+get_wander_expr() {
+	local scaled_wander
+
+	scaled_wander=$(awk "BEGIN {print $wander / \
+		sqrt($update_interval < 0 ? 2^-($update_interval) : 1)}")
+
+	echo "(+ $freq_offset (sum (* $scaled_wander (normal))))"
+}
+
+
+get_delay_expr() {
+	local direction=$1 asym
+
+	if [ $jitter_asymmetry == "0.0" ]; then
+		asym=""
+	elif [ $direction = "up" ]; then
+		asym=$(awk "BEGIN {print 1 - 2 * $jitter_asymmetry}")
+	elif [ $direction = "down" ]; then
+		asym=$(awk "BEGIN {print 1 + 2 * $jitter_asymmetry}")
+	fi
+	echo "(+ $base_delay (* $asym $jitter (exponential)))"
+}
+
+get_refclock_expr() {
+	echo "(+ $refclock_offset (* $refclock_jitter (normal)))"
+}
+
+get_chronyd_nodes() {
+	echo $[$servers * $server_strata + $clients]
+}
+
+get_node_name() {
+	local index=$1
+
+	if [ $dns -ne 0 ]; then
+		echo "node$index.net1.clk"
+	else
+		echo "192.168.123.$index"
+	fi
+}
+
+get_chronyd_conf() {
+	local i stratum=$1 peer=$2
+
+	if [ $stratum -eq 1 ]; then
+		echo "local stratum 1"
+		echo "$server_conf"
+	elif [ $stratum -le $server_strata ]; then
+		for i in $(seq 1 $servers); do
+			echo "server $(get_node_name $[$servers * ($stratum - 2) + $i]) $server_server_options"
+		done
+		for i in $(seq 1 $peers); do
+			[ $i -eq $peer -o $i -gt $servers ] && continue
+			echo -n "peer $(get_node_name $[$servers * ($stratum - 1) + $i]) $server_peer_options "
+			[ $i -lt $peer ] && echo "$server_lpeer_options" || echo "$server_rpeer_options"
+		done
+		echo "$server_conf"
+	else
+		echo "deny"
+		if [ -n "$client_server_conf" ]; then
+			echo "$client_server_conf"
+		else
+			for i in $(seq 1 $servers); do
+				echo "server $(get_node_name $[$servers * ($stratum - 2) + $i]) $client_server_options"
+			done
+		fi
+		for i in $(seq 1 $peers); do
+			[ $i -eq $peer -o $i -gt $clients ] && continue
+			echo -n "peer $(get_node_name $[$servers * ($stratum - 1) + $i]) $client_peer_options "
+			[ $i -lt $peer ] && echo "$client_lpeer_options" || echo "$client_rpeer_options"
+		done
+		echo "$client_conf"
+	fi
+}
+
+# Check if chrony was built with specified option in config.h
+check_config_h() {
+	local pattern=$1
+	grep -q "^#define $pattern" ../../config.h
+}
+
+# Check if the clock was well synchronized
+check_sync() {
+	local i sync_time max_time_error max_freq_error ret=0
+	local rms_time_error rms_freq_error
+
+	test_message 2 1 "checking clock sync time, max/rms time/freq error:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		[ $i -gt $[$servers * $server_strata] ] || continue
+
+		sync_time=$(find_sync tmp/log.offset tmp/log.freq $i \
+			$time_max_limit $freq_max_limit 1.0)
+		max_time_error=$(get_stat 'Maximum absolute offset' $i)
+		max_freq_error=$(get_stat 'Maximum absolute frequency' $i)
+		rms_time_error=$(get_stat 'RMS offset' $i)
+		rms_freq_error=$(get_stat 'RMS frequency' $i)
+
+		test_message 3 0 "node $i: $sync_time $(printf '%.2e %.2e %.2e %.2e' \
+			$max_time_error $max_freq_error $rms_time_error $rms_freq_error)"
+
+		check_stat $sync_time $min_sync_time $max_sync_time && \
+			check_stat $max_time_error 0.0 $time_max_limit && \
+			check_stat $max_freq_error 0.0 $freq_max_limit && \
+			check_stat $rms_time_error 0.0 $time_rms_limit && \
+			check_stat $rms_freq_error 0.0 $freq_rms_limit && \
+			test_ok || test_bad
+
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if chronyd exited properly
+check_chronyd_exit() {
+	local i ret=0
+
+	test_message 2 1 "checking chronyd exit:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		grep -q 'chronyd exiting' tmp/log.$i && \
+			! grep -q 'Adjustment.*exceeds.*exiting' tmp/log.$i && \
+			! grep -q 'Assertion.*failed' tmp/log.$i && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check for problems in source selection
+check_source_selection() {
+	local i ret=0
+
+	test_message 2 1 "checking source selection:"
+
+	for i in $(seq $[$servers * $server_strata + 1] $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		! grep -q 'no majority\|no selectable sources' tmp/log.$i && \
+			grep -q 'Selected source' tmp/log.$i && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if incoming and outgoing packet intervals are sane
+check_packet_interval() {
+	local i ret=0 mean_in_interval mean_out_interval min_in_interval min_out_interval
+
+	test_message 2 1 "checking mean/min incoming/outgoing packet interval:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		mean_in_interval=$(get_stat 'Mean incoming packet interval' $i)
+		mean_out_interval=$(get_stat 'Mean outgoing packet interval' $i)
+		min_in_interval=$(get_stat 'Minimum incoming packet interval' $i)
+		min_out_interval=$(get_stat 'Minimum outgoing packet interval' $i)
+
+		test_message 3 0 "node $i: $(printf '%.2e %.2e %.2e %.2e' \
+			$mean_in_interval $mean_out_interval $min_in_interval $min_out_interval)"
+
+		# Check that the mean intervals are non-zero and shorter than
+		# limit, incoming is not longer than outgoing for stratum 1
+		# servers, outgoing is not longer than incoming for clients,
+		# and the minimum outgoing interval is not shorter than the NTP
+		# sampling separation or iburst interval for clients
+		nodes=$[$servers * $server_strata + $clients]
+		check_stat $mean_in_interval 0.1 inf && \
+			check_stat $mean_out_interval 0.1 inf && \
+			([ $i -gt $servers ] || \
+				check_stat $mean_in_interval 0.0 $mean_out_interval 10*$jitter) && \
+			([ $i -le $[$servers * $server_strata] ] || \
+				check_stat $mean_out_interval $client_min_mean_out_interval \
+					$mean_in_interval 10*$jitter) && \
+			([ $i -le $[$servers * $server_strata] ] || \
+				check_stat $min_out_interval \
+					$([ $servers -gt 1 ] && echo 0.18 || echo 1.8) \
+					$client_max_min_out_interval) && \
+			test_ok || test_bad
+
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Compare chronyc output with specified pattern
+check_chronyc_output() {
+	local i ret=0 pattern=$1
+
+	test_message 2 1 "checking chronyc output:"
+
+	for i in $(seq $[$(get_chronyd_nodes) + 1] $[$(get_chronyd_nodes) + $clients]); do
+		test_message 3 0 "node $i:"
+
+		[[ "$(cat tmp/log.$i)" =~ $pattern ]] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check the number of messages matching a pattern in the client logs
+check_log_messages() {
+	local i count ret=0 pattern=$1 min=$2 max=$3
+
+	test_message 2 1 "checking number of messages \"$pattern\":"
+
+	for i in $(seq $[$servers * $server_strata + 1] $(get_chronyd_nodes)); do
+		count=$(grep "$pattern" tmp/log.$i | wc -l)
+		test_message 3 0 "node $i: $count"
+
+		[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check the number of messages matching a pattern in a specified file
+check_file_messages() {
+	local i count ret=0 pattern=$1 min=$2 max=$3
+	shift 3
+
+	test_message 2 1 "checking number of messages \"$pattern\":"
+
+	for i; do
+		count=$(grep "$pattern" tmp/$i | wc -l)
+		test_message 3 0 "$i: $count"
+
+		[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if only NTP port (123) was used
+check_packet_port() {
+	local i ret=0 port=123
+
+	test_message 2 1 "checking port numbers in packet log:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
+			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Print test settings which differ from default value
+print_nondefaults() {
+	local defoptname optname
+
+	test_message 2 1 "non-default settings:"
+	for defoptname in ${!default_*}; do
+		optname=${defoptname#default_}
+		[ "${!defoptname}" = "${!optname}" ] || \
+			test_message 3 1 $optname=${!optname}
+	done
+}
+
+run_simulation() {
+	local nodes=$1
+
+	test_message 2 0 "running simulation:"
+
+	start_server $nodes \
+		-n 2 \
+		-o tmp/log.offset -f tmp/log.freq -p tmp/log.packets \
+		-R $(awk "BEGIN {print $update_interval < 0 ? 2^-($update_interval) : 1}") \
+		-r $(awk "BEGIN {print $max_sync_time * 2^$update_interval}") \
+		-l $(awk "BEGIN {print $limit * 2^$update_interval}") && test_ok || test_error
+}
+
+run_test() {
+	local i j n stratum node nodes step start freq offset conf options
+
+	test_message 1 1 "network with $servers*$server_strata servers and $clients clients:"
+	print_nondefaults
+
+	nodes=$(get_chronyd_nodes)
+	[ -n "$chronyc_conf" ] && nodes=$[$nodes + $clients]
+
+	export CLKNETSIM_UNIX_SUBNET=$[$cmdmon_unix != 0 ? 2 : 0]
+
+	for i in $(seq 1 $nodes); do
+		echo "node${i}_shift_pll = $shift_pll"
+		for j in $(seq 1 $nodes); do
+			echo "node${i}_delay${j} = $(get_delay_expr up)"
+			echo "node${j}_delay${i} = $(get_delay_expr down)"
+		done
+	done > tmp/conf
+
+	node=1
+
+	for stratum in $(seq 1 $[$server_strata + 1]); do
+		[ $stratum -le $server_strata ] && n=$servers || n=$clients
+
+		for i in $(seq 1 $n); do
+			test_message 2 0 "starting node $node:"
+			if [ $stratum -eq 1 ]; then
+				step=$server_step
+				start=$server_start
+				freq=""
+				[ $i -le $falsetickers ] &&
+					offset=$i.0 || offset=$primary_time_offset
+				options=$server_chronyd_options
+			elif [ $stratum -le $server_strata ]; then
+				step=$server_step
+				start=$server_start
+				freq=$(get_wander_expr)
+				offset=0.0
+				options=$server_chronyd_options
+			else
+				step=$client_step
+				start=$client_start
+				freq=$(get_wander_expr)
+				offset=$time_offset
+				options=$client_chronyd_options
+			fi
+
+			conf=$(get_chronyd_conf $stratum $i $n)
+
+			[ -z "$freq" ] || echo "node${node}_freq = $freq" >> tmp/conf
+			[ -z "$step" ] || echo "node${node}_step = $step" >> tmp/conf
+			[ -z "$refclock_jitter" ] || \
+				echo "node${node}_refclock = $(get_refclock_expr)" >> tmp/conf
+			echo "node${node}_offset = $offset" >> tmp/conf
+			echo "node${node}_start = $start" >> tmp/conf
+			start_client $node chronyd "$conf" "" "$options" && \
+				test_ok || test_error
+
+			[ $? -ne 0 ] && return 1
+			node=$[$node + 1]
+		done
+	done
+
+	for i in $(seq 1 $[$nodes - $node + 1]); do
+		test_message 2 0 "starting node $node:"
+
+		options=$([ $dns -eq 0 ] && printf "%s" "-n")
+		if [ $cmdmon_unix -ne 0 ]; then
+			options+=" -h /clknetsim/unix/$[$node - $clients]:1"
+		else
+			options+=" -h $(get_node_name $[$node - $clients])"
+		fi
+
+		echo "node${node}_start = $chronyc_start" >> tmp/conf
+		start_client $node chronyc "$chronyc_conf" "" "$options $chronyc_options" && \
+			test_ok || test_error
+
+		[ $? -ne 0 ] && return 1
+		node=$[$node + 1]
+	done
+
+	run_simulation $nodes
+}
diff --git a/test/system/001-minimal b/test/system/001-minimal
new file mode 100755
index 0000000..107fa3f
--- /dev/null
+++ b/test/system/001-minimal
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "minimal configuration"
+
+minimal_config=1
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+
+test_pass
diff --git a/test/system/002-extended b/test/system/002-extended
new file mode 100755
index 0000000..7a6734f
--- /dev/null
+++ b/test/system/002-extended
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "extended configuration"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/003-memlock b/test/system/003-memlock
new file mode 100755
index 0000000..e4ab1bf
--- /dev/null
+++ b/test/system/003-memlock
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "memory locking"
+
+extra_chronyd_options="-m"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/004-priority b/test/system/004-priority
new file mode 100755
index 0000000..bf8a04b
--- /dev/null
+++ b/test/system/004-priority
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "process priority"
+
+extra_chronyd_options="-P 1"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/006-privdrop b/test/system/006-privdrop
new file mode 100755
index 0000000..6d7b0c9
--- /dev/null
+++ b/test/system/006-privdrop
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features PRIVDROP || test_skip "PRIVDROP support disabled"
+
+user="nobody"
+
+test_start "dropping of root privileges"
+
+minimal_config=1
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+
+test_pass
diff --git a/test/system/007-cmdmon b/test/system/007-cmdmon
new file mode 100755
index 0000000..04d14c2
--- /dev/null
+++ b/test/system/007-cmdmon
@@ -0,0 +1,181 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "chronyc commands"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+has_ipv6=$(check_chronyd_features IPV6 && ping6 -c 1 ::1 > /dev/null 2>&1 && echo 1 || echo 0)
+
+for command in \
+	"allow 1.2.3.4" \
+	"deny 1.2.3.4" \
+	"cmddeny" \
+	"cmdallow" \
+	"cmddeny 1.2.3.4" \
+	"cmdallow 1.2.3.4" \
+	"add server 127.123.1.1" \
+	"delete 127.123.1.1" \
+	"burst 1/1" \
+	"cyclelogs" \
+	"dfreq 1.0e-3" \
+	"doffset -0.1" \
+	"dump" \
+	"offline" \
+	"local off" \
+	"local" \
+	"online" \
+	"onoffline" \
+	"maxdelay $server 1e-1" \
+	"maxdelaydevratio $server 5.0" \
+	"maxdelayratio $server 3.0" \
+	"maxpoll $server 12" \
+	"maxupdateskew $server 10.0" \
+	"minpoll $server 10" \
+	"minstratum $server 1" \
+	"polltarget $server 10" \
+	"refresh" \
+	"rekey" \
+	"reload sources" \
+	"reselect" \
+	"reselectdist 1e-3" \
+	"reset sources" \
+	"smoothtime reset" \
+	"smoothtime activate" \
+; do
+	run_chronyc "$command" || test_fail
+	check_chronyc_output "^200 OK$" || test_fail
+done
+
+run_chronyc "accheck $server" || test_fail
+check_chronyc_output "^208 Access allowed$" || test_fail
+run_chronyc "accheck 1.2.3.4" || test_fail
+check_chronyc_output "^209 Access denied$" || test_fail
+
+run_chronyc "cmdaccheck 1.2.3.4" || test_fail
+check_chronyc_output "^208 Access allowed$" || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                      -     0    0    0    -    0    0    0    0$" \
+	|| test_chronyc
+
+run_chronyc "clients" || test_fail
+check_chronyc_output "^Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+127\.0\.0\.1               [0-9 ]+    0 [-0-9 ]+   -  [ 0-9]+       0      0   -     -$" \
+	|| test_fail
+
+run_chronyc "ntpdata $server" || test_fail
+check_chronyc_output "^Remote address  : 127\.0\.0\.1 \(7F000001\)
+Remote port     : [0-9]+
+Local address   : 127\.0\.0\.1 \(7F000001\)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 10
+Poll interval   : (-6|[0-9]+) \([0-9]+ seconds\)
+Precision       : [0-9 +-]+ \(0\.[0-9]+ seconds\)
+Root delay      : 0\.000000 seconds
+Root dispersion : 0\.000000 seconds
+Reference ID    : 7F7F0101 \(\)
+Reference time  : [A-Za-z0-9: ]+
+Offset          : [+-]0\.......... seconds
+Peer delay      : 0\.......... seconds
+Peer dispersion : 0\.......... seconds
+Response time   : 0\.......... seconds
+Jitter asymmetry: \+0\.00
+NTP tests       : 111 111 1110
+Interleaved     : No
+Authenticated   : No
+TX timestamping : (Daemon|Kernel)
+RX timestamping : (Daemon|Kernel)
+Total TX        : [0-9]+
+Total RX        : [0-9]+
+Total valid RX  : [0-9]+
+Total good RX   : [0-9]+$" || test_fail
+
+run_chronyc "selectdata" || test_fail
+check_chronyc_output "^S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+s 127\.0\.0\.1                 N ----- -----    0   1\.0    \+0ns    \+0ns  \?$" || test_fail
+
+run_chronyc "serverstats" || test_fail
+check_chronyc_output "^NTP packets received       : [0-9]+
+NTP packets dropped        : 0
+Command packets received   : [0-9]+
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 0
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 0
+Interleaved NTP packets    : 0
+NTP timestamps held        : 0
+NTP timestamp span         : 0$"|| test_fail
+
+run_chronyc "manual on" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "settime now" || test_fail
+check_chronyc_output "^200 OK
+Clock was.*$" || test_fail
+
+run_chronyc "manual delete 0" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "settime now" || test_fail
+check_chronyc_output "^200 OK
+Clock was.*$" || test_fail
+
+run_chronyc "manual list" || test_fail
+check_chronyc_output "^210 n_samples = 1
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0.*$" || test_fail
+
+run_chronyc "manual reset" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "manual off" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "shutdown" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+start_chronyd || test_fail
+
+run_chronyc "makestep" && test_fail
+check_chronyc_output "500 Failure" || test_fail
+
+run_chronyc "trimrtc" && test_fail
+check_chronyc_output "513 RTC driver not running" || test_fail
+
+run_chronyc "writertc" && test_fail
+check_chronyc_output "513 RTC driver not running" || test_fail
+
+chronyc_host=127.0.0.1
+
+run_chronyc "tracking" || test_fail
+check_chronyc_output "^Reference ID" || test_fail
+
+run_chronyc "makestep" && test_fail
+check_chronyc_output "^501 Not authorised$" || test_fail
+
+if [ "$has_ipv6" = "1" ]; then
+	chronyc_host=::1
+
+	run_chronyc "tracking" || test_fail
+	check_chronyc_output "^Reference ID" || test_fail
+
+	run_chronyc "makestep" && test_fail
+	check_chronyc_output "^501 Not authorised$" || test_fail
+fi
+
+stop_chronyd || test_fail
+
+test_pass
diff --git a/test/system/008-confload b/test/system/008-confload
new file mode 100755
index 0000000..a7fc1d5
--- /dev/null
+++ b/test/system/008-confload
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "loading of configuration"
+
+minimal_config=1
+extra_chronyd_directives="
+include $TEST_DIR/conf1.d/conf.1
+confdir $TEST_DIR/conf1.d
+confdir $TEST_DIR/conf2.d $TEST_DIR/conf3.d $TEST_DIR/conf4.d
+sourcedir $TEST_DIR/conf5.d
+include $TEST_DIR/conf1.d/conf.2"
+
+mkdir $TEST_DIR/conf{1,2,3,4,5}.d
+
+echo "server 127.123.1.1" > $TEST_DIR/conf1.d/conf.1
+echo "server 127.123.1.2" > $TEST_DIR/conf1.d/conf.2
+echo "server 127.123.1.3" > $TEST_DIR/conf1.d/3.conf
+echo "server 127.123.1.4" > $TEST_DIR/conf1.d/4.conf
+echo "server 127.123.2.2" > $TEST_DIR/conf2.d/2.conf
+echo "server 127.123.2.3" > $TEST_DIR/conf2.d/3.conf
+echo "server 127.123.3.1" > $TEST_DIR/conf3.d/1.conf
+echo "server 127.123.3.2" > $TEST_DIR/conf3.d/2.conf
+echo "server 127.123.3.3" > $TEST_DIR/conf3.d/3.conf
+echo "server 127.123.4.1" > $TEST_DIR/conf4.d/1.conf
+echo "server 127.123.4.2" > $TEST_DIR/conf4.d/2.conf
+echo "server 127.123.4.3" > $TEST_DIR/conf4.d/3.conf
+echo "server 127.123.4.4" > $TEST_DIR/conf4.d/4.conf
+echo "server 127.123.5.1" > $TEST_DIR/conf5.d/1.sources
+echo "server 127.123.5.2" > $TEST_DIR/conf5.d/2.sources
+echo "server 127.123.5.3" > $TEST_DIR/conf5.d/3.sources
+
+start_chronyd || test_fail
+
+run_chronyc "sources" || test_fail
+check_chronyc_output "^[^=]*
+=*
+.. 127\.123\.1\.1 [^^]*
+.. 127\.123\.1\.3 [^^]*
+.. 127\.123\.1\.4 [^^]*
+.. 127\.123\.3\.1 [^^]*
+.. 127\.123\.2\.2 [^^]*
+.. 127\.123\.2\.3 [^^]*
+.. 127\.123\.4\.4 [^^]*
+.. 127\.123\.1\.2 [^^]*
+.. 127\.123\.5\.1 [^^]*
+.. 127\.123\.5\.2 [^^]*
+.. 127\.123\.5\.3 [^^]*$" || test_fail
+
+rm $TEST_DIR/conf5.d/1.sources
+echo "server 127.123.5.2 minpoll 7" > $TEST_DIR/conf5.d/2.sources
+echo > $TEST_DIR/conf5.d/3.sources
+echo "server 127.123.5.4" > $TEST_DIR/conf5.d/4.sources
+
+run_chronyc "reload sources" || test_fail
+
+run_chronyc "sources" || test_fail
+check_chronyc_output "^[^=]*
+=*
+.. 127\.123\.1\.1 [^^]*
+.. 127\.123\.1\.3 [^^]*
+.. 127\.123\.1\.4 [^^]*
+.. 127\.123\.3\.1 [^^]*
+.. 127\.123\.2\.2 [^^]*
+.. 127\.123\.2\.3 [^^]*
+.. 127\.123\.4\.4 [^^]*
+.. 127\.123\.1\.2 *[05]   6 [^^]*
+.. 127\.123\.5\.2 *[05]   7 [^^]*
+.. 127\.123\.5\.4 [^^]*$" || test_fail
+
+stop_chronyd || test_fail
+
+test_pass
diff --git a/test/system/009-binddevice b/test/system/009-binddevice
new file mode 100755
index 0000000..fc64ae2
--- /dev/null
+++ b/test/system/009-binddevice
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+[ "$(uname -s)" = "Linux" ] || test_skip "non-Linux system"
+
+test_start "binddevice directives"
+
+extra_chronyd_directives="
+binddevice lo
+bindacqdevice lo
+bindcmddevice lo"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "ntpdata $server" || test_fail
+check_chronyc_output "^Remote address" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/010-nts b/test/system/010-nts
new file mode 100755
index 0000000..a0b366e
--- /dev/null
+++ b/test/system/010-nts
@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features NTS || test_skip "NTS support disabled"
+certtool --help &> /dev/null || test_skip "certtool missing"
+
+test_start "NTS authentication"
+
+cat > $TEST_DIR/cert.cfg <<EOF
+cn = "chrony-nts-test"
+dns_name = "chrony-nts-test"
+ip_address = "$server"
+serial = 001
+activation_date = "$[$(date '+%Y') - 1]-01-01 00:00:00 UTC"
+expiration_date = "$[$(date '+%Y') + 2]-01-01 00:00:00 UTC"
+signing_key
+encryption_key
+EOF
+
+certtool --generate-privkey --key-type=ed25519 --outfile $TEST_DIR/server.key \
+	&> $TEST_DIR/certtool.log
+certtool --generate-self-signed --load-privkey $TEST_DIR/server.key \
+	--template $TEST_DIR/cert.cfg --outfile $TEST_DIR/server.crt &>> $TEST_DIR/certtool.log
+chown $user $TEST_DIR/server.*
+
+ntpport=$(get_free_port)
+ntsport=$(get_free_port)
+
+server_options="port $ntpport nts ntsport $ntsport"
+extra_chronyd_directives="
+port $ntpport
+ntsport $ntsport
+ntsserverkey $TEST_DIR/server.key
+ntsservercert $TEST_DIR/server.crt
+ntstrustedcerts $TEST_DIR/server.crt
+ntsdumpdir $TEST_LIBDIR
+ntsprocesses 3"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                    NTS     1   15  256    [0-9]    0    0    [78]  100$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+server_options="port $ntpport nts ntsport $((ntsport + 1))"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                    NTS     1   15  256    [0-9]    0    0    [78]  100$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/099-scfilter b/test/system/099-scfilter
new file mode 100755
index 0000000..6b098ac
--- /dev/null
+++ b/test/system/099-scfilter
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features SCFILTER || test_skip "SCFILTER support disabled"
+
+test_start "system call filter in non-destructive tests"
+
+for level in "-1" "1" "-2" "2"; do
+	test_message 1 1 "level $level:"
+	for test in 0[0-8][0-9]-*[^_]; do
+		test_message 2 0 "$test"
+		TEST_SCFILTER=$level "./$test" > /dev/null 2> /dev/null
+		result=$?
+
+		if [ $result != 0 ] && [ $result != 9 ] ; then
+			test_bad
+			test_fail
+		fi
+		test_ok
+	done
+done
+
+test_pass
diff --git a/test/system/100-clockupdate b/test/system/100-clockupdate
new file mode 100755
index 0000000..191e461
--- /dev/null
+++ b/test/system/100-clockupdate
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "update of system clock"
+
+clock_control=1
+minimal_config=1
+
+start_chronyd || test_fail
+run_chronyc "dfreq 1e-3" || test_fail
+check_chronyc_output "200 OK" || test_fail
+
+before=$(date '+%s')
+run_chronyc "doffset -1.0" || test_fail
+check_chronyc_output "200 OK" || test_fail
+run_chronyc "makestep" || test_fail
+check_chronyc_output "200 OK" || test_fail
+after=$(date '+%s')
+
+test_message 1 0 "checking system clock"
+[ "$before" -lt "$after" ] && test_ok || test_bad || test_fail
+
+run_chronyc "doffset 1.0" || test_fail
+run_chronyc "makestep" || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_message_count "System clock was stepped by" 2 2 || test_fail
+
+test_pass
diff --git a/test/system/101-rtc b/test/system/101-rtc
new file mode 100755
index 0000000..68bce68
--- /dev/null
+++ b/test/system/101-rtc
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features RTC || test_skip "RTC support disabled"
+[ -c "/dev/rtc" ] || test_skip "missing /dev/rtc"
+
+test_start "real-time clock"
+
+minimal_config=1
+extra_chronyd_options="-s"
+extra_chronyd_directives="rtcfile $TEST_DIR/rtcfile"
+echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
+
+test_pass
diff --git a/test/system/102-hwtimestamp b/test/system/102-hwtimestamp
new file mode 100755
index 0000000..6b86d20
--- /dev/null
+++ b/test/system/102-hwtimestamp
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+[ "$(uname -s)" = "Linux" ] || test_skip "non-Linux system"
+
+hwts_iface=""
+for iface_path in /sys/class/net/*; do
+	iface=$(basename "$iface_path")
+	if ethtool -T "$iface" 2> /dev/null | grep -q '	all\($\| \)'; then
+		hwts_iface="$iface"
+		break
+	fi
+done
+
+[ -n "$hwts_iface" ] || test_skip "no HW timestamping interface found"
+
+test_start "hardware timestamping"
+
+minimal_config=1
+extra_chronyd_directives="hwtimestamp $hwts_iface"
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_message_count "Enabled HW timestamping on $hwts_iface" 1 1 || test_fail
+
+test_pass
diff --git a/test/system/103-refclock b/test/system/103-refclock
new file mode 100755
index 0000000..e5b74e0
--- /dev/null
+++ b/test/system/103-refclock
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features REFCLOCK || test_skip "refclock support disabled"
+
+test_start "reference clocks"
+
+extra_chronyd_directives="
+refclock SOCK $TEST_DIR/refclock.sock
+refclock SHM 100"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/104-systemdirs b/test/system/104-systemdirs
new file mode 100755
index 0000000..15508dc
--- /dev/null
+++ b/test/system/104-systemdirs
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+TEST_LIBDIR=${CHRONY_LIBDIR:-/var/lib/chrony}
+TEST_LOGDIR=${CHRONY_LOGDIR:-/var/log/chrony}
+TEST_RUNDIR=${CHRONY_RUNDIR:-/var/run/chrony}
+
+. ./test.common
+
+user=$(ls -ld "$TEST_RUNDIR" 2> /dev/null | awk '{print $3}')
+
+test_start "system directories"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/199-scfilter b/test/system/199-scfilter
new file mode 100755
index 0000000..29b7cc3
--- /dev/null
+++ b/test/system/199-scfilter
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features SCFILTER || test_skip "SCFILTER support disabled"
+
+test_start "system call filter in destructive tests"
+
+for level in "-1" "1" "-2" "2"; do
+	test_message 1 1 "level $level:"
+	for test in 1[0-8][0-9]-*[^_]; do
+		test_message 2 0 "$test"
+		TEST_SCFILTER=$level "./$test" > /dev/null 2> /dev/null
+		result=$?
+
+		if [ $result != 0 ] && [ $result != 9 ] ; then
+			test_bad
+			test_fail
+		fi
+		test_ok
+	done
+done
+
+test_pass
diff --git a/test/system/run b/test/system/run
new file mode 100755
index 0000000..5516ed4
--- /dev/null
+++ b/test/system/run
@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+
+print_help() {
+	echo "$1 [-a] [-d] [TEST]..."
+}
+
+run_test() {
+	local result name=$1
+
+	if [ $destructive -ne 1 ] && [[ "$name" == 1[0-9][0-9]-* ]]; then
+		echo "SKIP (destructive test)"
+		return 9
+	fi
+
+	./$name
+	result=$?
+
+	if [ $result -ne 0 -a $result -ne 9 ]; then
+		if [ $abort_on_fail -ne 0 ]; then
+			exit 1
+		fi
+	fi
+
+	return $result
+}
+
+passed=() failed=() skipped=()
+
+abort_on_fail=0
+destructive=0
+
+while getopts ":ad" opt; do
+	case $opt in
+		a) abort_on_fail=1;;
+		d) destructive=1;;
+		*) print_help "$0"; exit 3;;
+	esac
+done
+
+shift $[$OPTIND - 1]
+
+[ $# -gt 0 ] && tests=($@) || tests=([0-9]*-*[^_])
+
+for test in "${tests[@]}"; do
+	printf "%s   " "$test"
+	run_test $test
+	result=$?
+	echo
+
+	case $result in
+		0) passed=(${passed[@]} $test);;
+		9) skipped=(${skipped[@]} $test);;
+		*) failed=(${failed[@]} $test);;
+	esac
+done
+
+echo
+echo "SUMMARY:"
+echo "  TOTAL  $[${#passed[@]} + ${#failed[@]} + ${#skipped[@]}]"
+echo "  PASSED ${#passed[@]}"
+echo "  FAILED ${#failed[@]}    (${failed[@]})"
+echo "  SKIPPED ${#skipped[@]}   (${skipped[@]})"
+
+[ ${#failed[@]} -eq 0 ]
diff --git a/test/system/test.common b/test/system/test.common
new file mode 100644
index 0000000..7005c9e
--- /dev/null
+++ b/test/system/test.common
@@ -0,0 +1,373 @@
+# Copyright (C) Miroslav Lichvar  2009
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of version 2 of the GNU General Public License as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+export LC_ALL=C
+export PATH=${CHRONY_PATH:-../..}:$PATH
+
+TEST_DIR=${TEST_DIR:-$(pwd)/tmp}
+TEST_LIBDIR=${TEST_LIBDIR:-$TEST_DIR}
+TEST_LOGDIR=${TEST_LOGDIR:-$TEST_DIR}
+TEST_RUNDIR=${TEST_RUNDIR:-$TEST_DIR}
+TEST_SCFILTER=${TEST_SCFILTER:-0}
+
+test_start() {
+	check_chronyd_features NTP CMDMON || test_skip "NTP/CMDMON support disabled"
+
+	[ "${#TEST_DIR}" -ge 5 ] || test_skip "invalid TEST_DIR"
+
+	rm -rf "$TEST_DIR"
+	mkdir -p "$TEST_DIR" && chmod 700 "$TEST_DIR" || test_skip "could not create $TEST_DIR"
+
+	[ -d "$TEST_LIBDIR" ] || test_skip "missing $TEST_LIBDIR"
+	[ -d "$TEST_LOGDIR" ] || test_skip "missing $TEST_LOGDIR"
+	[ -d "$TEST_RUNDIR" ] || test_skip "missing $TEST_RUNDIR"
+
+	rm -f "$TEST_LIBDIR"/* "$TEST_LOGDIR"/* "$TEST_RUNDIR"/*
+
+	if [ "$user" != "root" ]; then
+		id -u "$user" > /dev/null 2> /dev/null || test_skip "missing user $user"
+		chown "$user:$(id -g "$user")" "$TEST_DIR" || test_skip "could not chown $TEST_DIR"
+		su "$user" -s /bin/sh -c "touch $TEST_DIR/test" 2> /dev/null || \
+			test_skip "$user cannot access $TEST_DIR"
+		rm "$TEST_DIR/test"
+	fi
+
+	echo "Testing $*:"
+}
+
+test_pass() {
+	echo "PASS"
+	exit 0
+}
+
+test_fail() {
+	echo "FAIL"
+	exit 1
+}
+
+test_skip() {
+	local msg=$1
+
+	[ -n "$msg" ] && echo "SKIP ($msg)" || echo "SKIP"
+	exit 9
+}
+
+test_ok() {
+	pad_line
+	echo -e "\tOK"
+	return 0
+}
+
+test_bad() {
+	pad_line
+	echo -e "\tBAD"
+	return 1
+}
+
+test_error() {
+	pad_line
+	echo -e "\tERROR"
+	return 1
+}
+
+chronyd=$(command -v chronyd)
+chronyc=$(command -v chronyc)
+
+[ $EUID -eq 0 ] || test_skip "not root"
+
+[ -x "$chronyd" ] || test_skip "chronyd not found"
+[ -x "$chronyc" ] || test_skip "chronyc not found"
+
+if netstat -aln > /dev/null 2> /dev/null; then
+	port_list_command="netstat -aln"
+elif ss -atun > /dev/null 2> /dev/null; then
+	port_list_command="ss -atun"
+else
+	test_skip "missing netstat or ss"
+fi
+
+# Default test testings
+default_minimal_config=0
+default_extra_chronyd_directives=""
+default_extra_chronyd_options=""
+default_clock_control=0
+default_server=127.0.0.1
+default_server_name=127.0.0.1
+default_server_options=""
+default_user=root
+
+# Initialize test settings from their defaults
+for defoptname in ${!default_*}; do
+	optname=${defoptname#default_}
+	[ -z "${!optname}" ] && declare "$optname"="${!defoptname}"
+done
+
+msg_length=0
+pad_line() {
+	local line_length=56
+	[ $msg_length -lt $line_length ] && \
+		printf "%$((line_length - msg_length))s" ""
+	msg_length=0
+}
+
+# Print aligned message
+test_message() {
+	local level=$1 eol=$2
+	shift 2
+	local msg="$*"
+
+	while [ "$level" -gt 0 ]; do
+		echo -n "  "
+		level=$((level - 1))
+		msg_length=$((msg_length + 2))
+	done
+	echo -n "$msg"
+
+	msg_length=$((msg_length + ${#msg}))
+	if [ "$eol" -ne 0 ]; then
+		echo
+		msg_length=0
+	fi
+}
+
+# Check if chronyd has specified features
+check_chronyd_features() {
+	local feature features
+
+	features=$($chronyd -v | sed 's/.*(\(.*\)).*/\1/')
+
+	for feature; do
+		echo "$features" | grep -q "+$feature" || return 1
+	done
+}
+
+# Print test settings which differ from default value
+print_nondefaults() {
+	local defoptname optname
+
+	test_message 1 1 "non-default settings:"
+	for defoptname in ${!default_*}; do
+		optname=${defoptname#default_}
+		[ "${!defoptname}" = "${!optname}" ] || \
+			test_message 2 1 "$optname"=${!optname}
+	done
+}
+
+get_conffile() {
+	echo "$TEST_DIR/chronyd.conf"
+}
+
+get_pidfile() {
+	echo "$TEST_RUNDIR/chronyd.pid"
+}
+
+get_logfile() {
+	echo "$TEST_LOGDIR/chronyd.log"
+}
+
+get_cmdsocket() {
+	echo "$TEST_RUNDIR/chronyd.sock"
+}
+
+# Find a free port in the 10000-20000 range (their use is racy)
+get_free_port() {
+	local port
+
+	while true; do
+		port=$((RANDOM % 10000 + 10000))
+		$port_list_command | grep -q '^\(tcp\|udp\).*[:.]'"$port " && continue
+		break
+	done
+
+	echo $port
+}
+
+generate_chrony_conf() {
+	local ntpport cmdport
+
+	ntpport=$(get_free_port)
+	cmdport=$(get_free_port)
+
+	echo "0.0 10000" > "$TEST_LIBDIR/driftfile"
+	echo "1 MD5 abcdefghijklmnopq" > "$TEST_DIR/keys"
+	chown "$user:$(id -g "$user")" "$TEST_LIBDIR/driftfile" "$TEST_DIR/keys"
+	echo "0.0" > "$TEST_DIR/tempcomp"
+
+	(
+		echo "pidfile $(get_pidfile)"
+		echo "bindcmdaddress $(get_cmdsocket)"
+		echo "port $ntpport"
+		echo "cmdport $cmdport"
+
+		echo "$extra_chronyd_directives"
+
+		[ "$minimal_config" -ne 0 ] && exit 0
+
+		echo "allow"
+		echo "cmdallow"
+		echo "local"
+
+		echo "server $server_name port $ntpport minpoll -6 maxpoll -6 $server_options"
+
+		[ "$server" = "127.0.0.1" ] && echo "bindacqaddress $server"
+		echo "bindaddress 127.0.0.1"
+		echo "bindcmdaddress 127.0.0.1"
+		echo "dumpdir $TEST_RUNDIR"
+		echo "logdir $TEST_LOGDIR"
+		echo "log tempcomp rawmeasurements refclocks statistics tracking rtc"
+		echo "logbanner 0"
+		echo "smoothtime 100.0 0.001"
+		echo "leapsectz right/UTC"
+		echo "dscp 46"
+
+		echo "include /dev/null"
+		echo "keyfile $TEST_DIR/keys"
+		echo "driftfile $TEST_LIBDIR/driftfile"
+		echo "tempcomp $TEST_DIR/tempcomp 0.1 0 0 0 0"
+
+	) > "$(get_conffile)"
+}
+
+get_chronyd_options() {
+	[ "$clock_control" -eq 0 ] && echo "-x"
+	echo "-l $(get_logfile)"
+	echo "-f $(get_conffile)"
+	echo "-u $user"
+	echo "-F $TEST_SCFILTER"
+	echo "$extra_chronyd_options"
+}
+
+# Start a chronyd instance
+start_chronyd() {
+	local pid pidfile=$(get_pidfile)
+
+	print_nondefaults
+	test_message 1 0 "starting chronyd"
+
+	generate_chrony_conf
+
+	trap stop_chronyd EXIT
+
+	rm -f "$TEST_LOGDIR"/*.log
+
+	$CHRONYD_WRAPPER "$chronyd" $(get_chronyd_options) > "$TEST_DIR/chronyd.out" 2>&1
+
+	[ $? -eq 0 ] && [ -f "$pidfile" ] && ps -p "$(cat "$pidfile")" > /dev/null && test_ok || test_error
+}
+
+wait_for_sync() {
+	local prev_length
+
+	test_message 1 0 "waiting for synchronization"
+	prev_length=$msg_length
+
+	for i in $(seq 1 10); do
+		run_chronyc "ntpdata $server" > /dev/null 2>&1 || break
+		if check_chronyc_output "Total RX +: [1-9]" > /dev/null 2>&1; then
+			msg_length=$prev_length
+			test_ok
+			return
+		fi
+		sleep 1
+	done
+
+	msg_length=$prev_length
+	test_error
+}
+
+# Stop the chronyd instance
+stop_chronyd() {
+	local pid pidfile
+
+	pidfile=$(get_pidfile)
+	[ -f "$pidfile" ] || return 0
+
+	pid=$(cat "$pidfile")
+
+	test_message 1 0 "stopping chronyd"
+
+	if ! kill "$pid" 2> /dev/null; then
+		test_error
+		return
+	fi
+
+	# Wait for the process to terminate (we cannot use "wait")
+	while ps -p "$pid" > /dev/null; do
+		sleep 0.1
+	done
+
+	test_ok
+}
+
+# Check chronyd log for expected and unexpected messages
+check_chronyd_messages() {
+	local logfile=$(get_logfile)
+
+	test_message 1 0 "checking chronyd messages"
+
+	grep -q 'chronyd exiting' "$logfile" && \
+		([ "$clock_control" -eq 0 ] || ! grep -q 'Disabled control of system clock' "$logfile") && \
+		([ "$clock_control" -ne 0 ] || grep -q 'Disabled control of system clock' "$logfile") && \
+		([ "$minimal_config" -ne 0 ] || grep -q 'Frequency .* read from' "$logfile") && \
+		grep -q 'chronyd exiting' "$logfile" && \
+		! grep -q 'Could not' "$logfile" && \
+		! grep -q 'Disabled command socket' "$logfile" && \
+		test_ok || test_bad
+}
+
+# Check the number of messages matching a pattern in a specified file
+check_chronyd_message_count() {
+	local count pattern=$1 min=$2 max=$3 logfile=$(get_logfile)
+
+	test_message 1 0 "checking message \"$pattern\""
+
+	count=$(grep "$pattern" "$(get_logfile)" | wc -l)
+
+	[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && test_ok || test_bad
+}
+
+# Check the logs and dump file for measurements and a clock update
+check_chronyd_files() {
+	test_message 1 0 "checking chronyd files"
+
+	grep -q " $server .* 111 111 1110 " "$TEST_LOGDIR/measurements.log" && \
+		[ -f "$TEST_LOGDIR/tempcomp.log" ] && [ "$(wc -l < "$TEST_LOGDIR/tempcomp.log")" -ge 2 ] && \
+		test_ok || test_bad
+}
+
+# Run a chronyc command
+run_chronyc() {
+	local host=$chronyc_host options="-n -m"
+
+	test_message 1 0 "running chronyc $([ -n "$host" ] && echo "@$host ")$*"
+
+	if [ -z "$host" ]; then
+		host="$(get_cmdsocket)"
+	else
+		options="$options -p $(grep cmdport "$(get_conffile)" | awk '{print $2}')"
+	fi
+
+	$CHRONYC_WRAPPER "$chronyc" -h "$host" $options "$@" > "$TEST_DIR/chronyc.out" && \
+		test_ok || test_error
+}
+
+# Compare chronyc output with specified pattern
+check_chronyc_output() {
+	local pattern=$1
+
+	test_message 1 0 "checking chronyc output"
+
+	[[ "$(cat "$TEST_DIR/chronyc.out")" =~ $pattern ]] && test_ok || test_bad
+}
diff --git a/test/unit/Makefile.in b/test/unit/Makefile.in
new file mode 100644
index 0000000..9979840
--- /dev/null
+++ b/test/unit/Makefile.in
@@ -0,0 +1,48 @@
+TEST_WRAPPER =
+CHRONY_SRCDIR = ../..
+
+CC = @CC@
+CFLAGS = @CFLAGS@
+CPPFLAGS = -I$(CHRONY_SRCDIR) @CPPFLAGS@
+LDFLAGS = @LDFLAGS@ @LIBS@ @EXTRA_LIBS@
+
+SHARED_OBJS = test.o
+
+TEST_OBJS := $(sort $(patsubst %.c,%.o,$(wildcard *.c)))
+TESTS := $(patsubst %.o,%.test,$(filter-out $(SHARED_OBJS),$(TEST_OBJS)))
+
+CHRONYD_OBJS := $(patsubst %.o,$(CHRONY_SRCDIR)/%.o,$(filter-out main.o,\
+		  $(filter %.o,$(shell $(MAKE) -f $(CHRONY_SRCDIR)/Makefile \
+					print-chronyd-objects NODEPS=1))))
+
+all: $(TESTS)
+
+$(CHRONYD_OBJS): ;
+
+%.test: %.o $(SHARED_OBJS) $(CHRONYD_OBJS)
+	$(CC) $(CFLAGS) -o $@ $(filter-out $(CHRONY_SRCDIR)/$<,$^) $(LDFLAGS)
+
+%.o: %.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) -c $<
+
+check: $(TESTS)
+	@ret=0; \
+	for t in $^; do \
+	  $(TEST_WRAPPER) ./$$t || ret=1; \
+	done; \
+	exit $$ret
+
+clean:
+	rm -f *.o *.gcda *.gcno core.* $(TESTS)
+	rm -rf .deps
+
+distclean: clean
+	rm -f Makefile
+
+.deps:
+	@mkdir .deps
+
+.deps/%.d: %.c | .deps
+	@$(CC) -MM $(CPPFLAGS) -MT '$(<:%.c=%.o) $@' $< -o $@
+
+-include $(TEST_OBJS:%.o=.deps/%.d)
diff --git a/test/unit/addrfilt.c b/test/unit/addrfilt.c
new file mode 100644
index 0000000..b236073
--- /dev/null
+++ b/test/unit/addrfilt.c
@@ -0,0 +1,83 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <addrfilt.c>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+void
+test_unit(void)
+{
+  int i, j, sub, maxsub;
+  IPAddr ip;
+  ADF_AuthTable table;
+
+  table = ADF_CreateTable();
+
+  for (i = 0; i < 100; i++) {
+    for (j = 0; j < 1000; j++) {
+      if (j % 2) {
+        maxsub = 32;
+        TST_GetRandomAddress(&ip, IPADDR_INET4, -1);
+      } else {
+        maxsub = 128;
+        TST_GetRandomAddress(&ip, IPADDR_INET6, -1);
+      }
+
+      DEBUG_LOG("address %s", UTI_IPToString(&ip));
+
+      sub = random() % (maxsub + 1);
+
+      TEST_CHECK(!ADF_IsAllowed(table, &ip));
+      ADF_Allow(table, &ip, sub);
+      TEST_CHECK(ADF_IsAllowed(table, &ip));
+
+      if (sub < maxsub) {
+        TST_SwapAddressBit(&ip, sub);
+        TEST_CHECK(ADF_IsAllowed(table, &ip));
+      }
+
+      if (sub > 0) {
+        TST_SwapAddressBit(&ip, sub - 1);
+        TEST_CHECK(!ADF_IsAllowed(table, &ip));
+        if (sub % 4 != 1) {
+          ADF_Deny(table, &ip, sub - 1);
+          TST_SwapAddressBit(&ip, sub - 1);
+          TEST_CHECK(!ADF_IsAllowed(table, &ip));
+        }
+      }
+
+      if (sub > 4) {
+        ADF_AllowAll(table, &ip, sub - 4);
+        TEST_CHECK(ADF_IsAllowed(table, &ip));
+      }
+
+      ADF_DenyAll(table, &ip, 0);
+    }
+
+    ip.family = IPADDR_INET4;
+    ADF_DenyAll(table, &ip, 0);
+    ip.family = IPADDR_INET6;
+    ADF_DenyAll(table, &ip, 0);
+  }
+
+  ADF_DestroyTable(table);
+}
diff --git a/test/unit/clientlog.c b/test/unit/clientlog.c
new file mode 100644
index 0000000..f59e130
--- /dev/null
+++ b/test/unit/clientlog.c
@@ -0,0 +1,292 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_NTP) || defined(FEAT_CMDMON)
+
+#include <clientlog.c>
+
+static uint64_t
+get_random64(void)
+{
+  return ((uint64_t)random() << 40) ^ ((uint64_t)random() << 20) ^ random();
+}
+
+void
+test_unit(void)
+{
+  uint64_t ts64, prev_first_ts64, prev_last_ts64, max_step;
+  uint32_t index2, prev_first, prev_size;
+  struct timespec ts, ts2;
+  int i, j, k, index, shift;
+  CLG_Service s;
+  NTP_int64 ntp_ts;
+  IPAddr ip;
+  char conf[][100] = {
+    "clientloglimit 20000",
+    "ratelimit interval 3 burst 4 leak 3",
+    "cmdratelimit interval 3 burst 4 leak 3",
+    "ntsratelimit interval 6 burst 8 leak 3",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  CLG_Initialise();
+
+  TEST_CHECK(ARR_GetSize(records) == 16);
+
+  for (i = 0; i < 500; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    ts.tv_sec = (time_t)random() & 0x0fffffff;
+    ts.tv_nsec = 0;
+
+    for (j = 0; j < 1000; j++) {
+      TST_GetRandomAddress(&ip, IPADDR_UNSPEC, i % 8 ? -1 : i / 8 % 9);
+      DEBUG_LOG("address %s", UTI_IPToString(&ip));
+
+      s = random() % MAX_SERVICES;
+      index = CLG_LogServiceAccess(s, &ip, &ts);
+      TEST_CHECK(index >= 0);
+      CLG_LimitServiceRate(s, index);
+
+      UTI_AddDoubleToTimespec(&ts, (1 << random() % 14) / 100.0, &ts);
+    }
+  }
+
+  DEBUG_LOG("records %u", ARR_GetSize(records));
+  TEST_CHECK(ARR_GetSize(records) == 128);
+
+  s = CLG_NTP;
+
+  for (i = j = 0; i < 10000; i++) {
+    ts.tv_sec += 1;
+    index = CLG_LogServiceAccess(s, &ip, &ts);
+    TEST_CHECK(index >= 0);
+    if (!CLG_LimitServiceRate(s, index))
+      j++;
+  }
+
+  DEBUG_LOG("requests %d responses %d", i, j);
+  TEST_CHECK(j * 4 < i && j * 6 > i);
+
+  TEST_CHECK(!ntp_ts_map.timestamps);
+
+  UTI_ZeroNtp64(&ntp_ts);
+  CLG_SaveNtpTimestamps(&ntp_ts, NULL);
+  TEST_CHECK(ntp_ts_map.timestamps);
+  TEST_CHECK(ntp_ts_map.first == 0);
+  TEST_CHECK(ntp_ts_map.size == 0);
+  TEST_CHECK(ntp_ts_map.max_size == 128);
+  TEST_CHECK(ARR_GetSize(ntp_ts_map.timestamps) == ntp_ts_map.max_size);
+
+  TEST_CHECK(ntp_ts_map.max_size > NTPTS_INSERT_LIMIT);
+
+  for (i = 0; i < 200; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    max_step = (1ULL << (i % 50));
+    ts64 = 0ULL - 100 * max_step;
+
+    if (i > 150)
+      ntp_ts_map.max_size = 1U << (i % 8);
+    assert(ntp_ts_map.max_size <= 128);
+    ntp_ts_map.first = i % ntp_ts_map.max_size;
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+    ntp_ts_map.slew_epoch = i * 400;
+
+    for (j = 0; j < 500; j++) {
+      do {
+        ts64 += get_random64() % max_step + 1;
+      } while (ts64 == 0ULL);
+
+      int64_to_ntp64(ts64, &ntp_ts);
+
+      if (random() % 10) {
+        UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+        UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
+      } else {
+        UTI_ZeroTimespec(&ts);
+      }
+
+      CLG_SaveNtpTimestamps(&ntp_ts,
+                            UTI_IsZeroTimespec(&ts) ? (random() % 2 ? &ts : NULL) : &ts);
+
+      if (j < ntp_ts_map.max_size) {
+        TEST_CHECK(ntp_ts_map.size == j + 1);
+        TEST_CHECK(ntp_ts_map.first == i % ntp_ts_map.max_size);
+      } else {
+        TEST_CHECK(ntp_ts_map.size == ntp_ts_map.max_size);
+        TEST_CHECK(ntp_ts_map.first == (i + j + ntp_ts_map.size + 1) % ntp_ts_map.max_size);
+      }
+      TEST_CHECK(ntp_ts_map.cached_index == ntp_ts_map.size - 1);
+      TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->slew_epoch == ntp_ts_map.slew_epoch);
+      TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
+      TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+
+      for (k = random() % 4; k > 0; k--) {
+        index2 = random() % ntp_ts_map.size;
+        int64_to_ntp64(get_ntp_tss(index2)->rx_ts, &ntp_ts);
+        if (random() % 2)
+          TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+
+        UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+        UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
+
+        ts2 = ts;
+        CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+        if ((get_ntp_tss(index2)->slew_epoch + 1) % (1U << 16) != ntp_ts_map.slew_epoch) {
+          TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+        } else {
+          TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - ntp_ts_map.slew_offset) <
+                     1.0e-9);
+        }
+
+        CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+
+        TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
+        TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+
+        if (random() % 2) {
+          uint16_t prev_epoch = ntp_ts_map.slew_epoch;
+          handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e-5, 1.0e-5),
+                      LCL_ChangeAdjust, NULL);
+          TEST_CHECK((prev_epoch + 1) % (1U << 16) == ntp_ts_map.slew_epoch);
+        }
+
+        if (ntp_ts_map.size > 1) {
+          index = random() % (ntp_ts_map.size - 1);
+          if (get_ntp_tss(index)->rx_ts + 1 != get_ntp_tss(index + 1)->rx_ts) {
+            int64_to_ntp64(get_ntp_tss(index)->rx_ts + 1, &ntp_ts);
+            TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+            int64_to_ntp64(get_ntp_tss(index + 1)->rx_ts - 1, &ntp_ts);
+            TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+            CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+            CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+          }
+        }
+
+        if (random() % 2) {
+          int64_to_ntp64(get_ntp_tss(0)->rx_ts - 1, &ntp_ts);
+          TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+          int64_to_ntp64(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts + 1, &ntp_ts);
+          TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+          CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+          CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+        }
+      }
+    }
+
+    for (j = 0; j < 500; j++) {
+      shift = (i % 3) * 26;
+
+      if (i % 7 == 0) {
+        while (ntp_ts_map.size < ntp_ts_map.max_size) {
+          ts64 += get_random64() >> (shift + 8);
+          int64_to_ntp64(ts64, &ntp_ts);
+          CLG_SaveNtpTimestamps(&ntp_ts, NULL);
+          if (ntp_ts_map.cached_index + NTPTS_INSERT_LIMIT < ntp_ts_map.size)
+            ts64 = get_ntp_tss(ntp_ts_map.size - 1)->rx_ts;
+        }
+      }
+      do {
+        if (ntp_ts_map.size > 1 && random() % 2) {
+          k = random() % (ntp_ts_map.size - 1);
+          ts64 = get_ntp_tss(k)->rx_ts +
+                 (get_ntp_tss(k + 1)->rx_ts - get_ntp_tss(k)->rx_ts) / 2;
+        } else {
+          ts64 = get_random64() >> shift;
+        }
+      } while (ts64 == 0ULL);
+
+      int64_to_ntp64(ts64, &ntp_ts);
+
+      prev_first = ntp_ts_map.first;
+      prev_size = ntp_ts_map.size;
+      prev_first_ts64 = get_ntp_tss(0)->rx_ts;
+      prev_last_ts64 = get_ntp_tss(prev_size - 1)->rx_ts;
+      CLG_SaveNtpTimestamps(&ntp_ts, NULL);
+
+      TEST_CHECK(find_ntp_rx_ts(ts64, &index2));
+
+      if (ntp_ts_map.size > 1) {
+        TEST_CHECK(ntp_ts_map.size > 0 && ntp_ts_map.size <= ntp_ts_map.max_size);
+        if (get_ntp_tss(index2)->flags & NTPTS_DISABLED)
+          continue;
+
+        TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts - ts64 <= NTPTS_FUTURE_LIMIT);
+
+        if ((int64_t)(prev_last_ts64 - ts64) <= NTPTS_FUTURE_LIMIT) {
+          TEST_CHECK(prev_size + 1 >= ntp_ts_map.size);
+          if (index2 + NTPTS_INSERT_LIMIT + 1 >= ntp_ts_map.size &&
+              !(index2 == 0 && NTPTS_INSERT_LIMIT < ntp_ts_map.max_size &&
+                ((NTPTS_INSERT_LIMIT == prev_size && (int64_t)(ts64 - prev_first_ts64) > 0) ||
+                 (NTPTS_INSERT_LIMIT + 1 == prev_size && (int64_t)(ts64 - prev_first_ts64) < 0))))
+            TEST_CHECK((prev_first + prev_size + 1) % ntp_ts_map.max_size ==
+                       (ntp_ts_map.first + ntp_ts_map.size) % ntp_ts_map.max_size);
+          else
+            TEST_CHECK(prev_first + prev_size == ntp_ts_map.first + ntp_ts_map.size);
+        }
+
+        TEST_CHECK((int64_t)(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts -
+                             get_ntp_tss(0)->rx_ts) > 0);
+        for (k = 0; k + 1 < ntp_ts_map.size; k++)
+          TEST_CHECK((int64_t)(get_ntp_tss(k + 1)->rx_ts - get_ntp_tss(k)->rx_ts) > 0);
+      }
+
+      if (random() % 10 == 0) {
+        CLG_DisableNtpTimestamps(&ntp_ts);
+        TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+      }
+
+      for (k = random() % 10; k > 0; k--) {
+        ts64 = get_random64() >> shift;
+        int64_to_ntp64(ts64, &ntp_ts);
+        CLG_GetNtpTxTimestamp(&ntp_ts, &ts);
+      }
+    }
+
+    if (random() % 2) {
+      handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e9, 1.0e9),
+                  LCL_ChangeUnknownStep, NULL);
+      TEST_CHECK(ntp_ts_map.size == 0);
+      TEST_CHECK(ntp_ts_map.cached_rx_ts == 0ULL);
+      TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+      CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+    }
+  }
+
+  CLG_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/cmac.c b/test/unit/cmac.c
new file mode 100644
index 0000000..be4ffbb
--- /dev/null
+++ b/test/unit/cmac.c
@@ -0,0 +1,109 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <cmac.h>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+#define MAX_KEY_LENGTH 64
+#define MAX_HASH_LENGTH 64
+
+struct cmac_test {
+  const char *name;
+  const unsigned char key[MAX_KEY_LENGTH];
+  int key_length;
+  const unsigned char hash[MAX_HASH_LENGTH];
+  int hash_length;
+};
+
+void
+test_unit(void)
+{
+  unsigned char data[] = "abcdefghijklmnopqrstuvwxyz0123456789";
+  unsigned char hash[MAX_HASH_LENGTH];
+  struct cmac_test tests[] = {
+    { "AES128", "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16,
+                "\xaf\x3c\xfe\xc2\x66\x71\x08\x04\xd4\xaf\x5b\x16\x2b\x11\xf4\x85", 16 },
+    { "AES256", "\x14\x02\x8e\x7d\x17\x3c\x2f\x4e\x17\x0f\x37\x96\xc3\x2c\xc5\x99"
+                "\x18\xdd\x55\x23\xb7\xd7\x9b\xc5\x76\x36\x88\x3f\xc5\x82\xb5\x83", 32,
+                "\xfe\xf7\x94\x96\x14\x04\x11\x0b\x87\xe4\xd4\x3f\x81\xb3\xb2\x2d", 16 },
+    { "", "", 0, "", 0 }
+  };
+
+  CMC_Algorithm algorithm;
+  CMC_Instance inst;
+  int i, j, length;
+
+#ifndef HAVE_CMAC
+  TEST_REQUIRE(0);
+#endif
+
+  TEST_CHECK(CMC_INVALID == 0);
+
+  for (i = 0; tests[i].name[0] != '\0'; i++) {
+    algorithm = UTI_CmacNameToAlgorithm(tests[i].name);
+    TEST_CHECK(algorithm != 0);
+    TEST_CHECK(CMC_GetKeyLength(algorithm) == tests[i].key_length);
+
+    DEBUG_LOG("testing %s", tests[i].name);
+
+    for (j = -1; j <= 128; j++) {
+      if (j == tests[i].key_length)
+        continue;
+      TEST_CHECK(!CMC_CreateInstance(algorithm, tests[i].key, j));
+    }
+
+    inst = CMC_CreateInstance(algorithm, tests[i].key, tests[i].key_length);
+    TEST_CHECK(inst);
+
+    TEST_CHECK(!CMC_CreateInstance(0, tests[i].key, tests[i].key_length));
+
+    TEST_CHECK(CMC_Hash(inst, data, -1, hash, sizeof (hash)) == 0);
+    TEST_CHECK(CMC_Hash(inst, data, sizeof (data) - 1, hash, -1) == 0);
+
+    for (j = 0; j <= sizeof (hash); j++) {
+      memset(hash, 0, sizeof (hash));
+      length = CMC_Hash(inst, data, sizeof (data) - 1, hash, j);
+
+#if 0
+      for (int k = 0; k < length; k++)
+        printf("\\x%02x", hash[k]);
+      printf("\n");
+#endif
+
+      if (j >= tests[i].hash_length)
+        TEST_CHECK(length == tests[i].hash_length);
+      else
+        TEST_CHECK(length == j);
+
+      TEST_CHECK(!memcmp(hash, tests[i].hash, length));
+    }
+
+    for (j = 0; j < sizeof (data); j++) {
+      length = CMC_Hash(inst, data, j, hash, sizeof (hash));
+      TEST_CHECK(length == tests[i].hash_length);
+    }
+
+    CMC_DestroyInstance(inst);
+  }
+}
diff --git a/test/unit/hash.c b/test/unit/hash.c
new file mode 100644
index 0000000..2f9ffef
--- /dev/null
+++ b/test/unit/hash.c
@@ -0,0 +1,131 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <hash.h>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+struct hash_test {
+  const char *name;
+  const unsigned char out[MAX_HASH_LENGTH];
+  int length;
+};
+
+void
+test_unit(void)
+{
+  unsigned char data1[] = "abcdefghijklmnopqrstuvwxyz";
+  unsigned char data2[] = "12345678910";
+  unsigned char out[MAX_HASH_LENGTH];
+  struct hash_test tests[] = {
+    { "MD5-NC",    "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16 },
+    { "MD5",       "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16 },
+    { "SHA1",      "\xd8\x85\xb3\x86\xce\xea\x93\xeb\x92\xcd\x7b\x94\xb9\x8d\xc2\x8e"
+                   "\x3e\x31\x13\xdd", 20},
+    { "SHA256",    "\x0e\x35\x14\xe7\x15\x7a\x1d\xdd\xea\x11\x78\xd3\x41\xf6\xb9\x3e"
+                   "\xa0\x42\x96\x73\x3c\x54\x74\x0b\xfa\x6b\x9e\x29\x59\xad\x69\xd3", 32 },
+    { "SHA384",    "\x2c\xeb\xbd\x4d\x95\xed\xad\x03\xed\x80\xc4\xf3\xa6\x10\x21\xde"
+                   "\x40\x69\x54\xed\x42\x70\xb8\x95\xb0\x6f\x01\x1d\x04\xdf\x57\xbc"
+                   "\x1d\xb5\x85\xbf\x4f\x03\x88\xd5\x83\x93\xbc\x81\x90\xb0\xa9\x9b", 48 },
+    { "SHA512",    "\x20\xba\xec\xcb\x68\x98\x33\x5b\x70\x26\x63\x13\xe2\xf7\x0e\x67"
+                   "\x08\xf3\x77\x4f\xbd\xeb\xc4\xa8\xc5\x94\xe2\x39\x40\x7e\xed\x0b"
+                   "\x69\x0e\x18\xa5\xa2\x03\x73\xe7\x1d\x20\x7d\x3f\xc8\x70\x2d\x64"
+                   "\x9e\x89\x6d\x20\x6a\x4a\x5a\x46\xe7\x4f\x2c\xf9\x0f\x0a\x54\xdc", 64 },
+    { "SHA3-224",  "\x3b\xa2\x22\x28\xdd\x26\x18\xec\x3b\xb9\x25\x39\x5e\xbd\x94\x25"
+                   "\xd4\x20\x8a\x76\x76\xc0\x3c\x5d\x9e\x0a\x06\x46", 28},
+    { "SHA3-256",  "\x26\xd1\x19\xb2\xc1\x64\xc8\xb8\x10\xd8\xa8\x1c\xb6\xa4\x0d\x29"
+                   "\x09\xc9\x8e\x2e\x2d\xde\x7a\x74\x8c\x43\x70\xb8\xaa\x0f\x09\x17", 32 },
+    { "SHA3-384",  "\x6a\x64\xb9\x89\x08\x29\xd0\xa7\x4b\x84\xba\xa6\x65\xf5\xe7\x54"
+                   "\xe2\x18\x12\xc3\x63\x34\xc6\xba\x26\xf5\x6e\x99\xe2\x54\xcc\x9d"
+                   "\x01\x10\x9d\xee\x35\x38\x04\x83\xe5\x71\x70\xd8\xc8\x99\x96\xd8", 48 },
+    { "SHA3-512",  "\xa8\xe3\x2b\x65\x1f\x87\x90\x73\x19\xc8\xa0\x3f\xe3\x85\x60\x3c"
+                   "\x39\xfc\xcb\xc1\x29\xe1\x23\x7d\x8b\x56\x54\xe3\x08\x9d\xf9\x74"
+                   "\x78\x69\x2e\x3c\x7e\x51\x1e\x9d\xab\x09\xbe\xe7\x6b\x1a\xa1\x22"
+                   "\x93\xb1\x2b\x82\x9d\x1e\xcf\xa8\x99\xc5\xec\x7b\x1d\x89\x07\x2b", 64 },
+    { "TIGER",     "\x1c\xcd\x68\x74\xca\xd6\xd5\x17\xba\x3e\x82\xaf\xbd\x70\xdc\x66"
+                   "\x99\xaa\xae\x16\x72\x59\xd1\x64", 24},
+    { "WHIRLPOOL", "\xe3\xcd\xe6\xbf\xe1\x8c\xe4\x4d\xc8\xb4\xa5\x7c\x36\x8d\xc8\x8a"
+                   "\x8b\xad\x52\x24\xc0\x4e\x99\x5b\x7e\x86\x94\x2d\x10\x56\x12\xa3"
+                   "\x29\x2a\x65\x0f\x9e\x07\xbc\x15\x21\x14\xe6\x07\xfc\xe6\xb9\x2f"
+                   "\x13\xe2\x57\xe9\x0a\xb0\xd2\xf4\xa3\x20\x36\x9c\x88\x92\x8e\xc9", 64 },
+    { "", "", 0 }
+  };
+
+  HSH_Algorithm algorithm;
+  int i, j, hash_id, length;
+
+  TEST_CHECK(HSH_INVALID == 0);
+
+  for (i = 0; tests[i].name[0] != '\0'; i++) {
+    algorithm = UTI_HashNameToAlgorithm(tests[i].name);
+    if (strcmp(tests[i].name, "MD5-NC") == 0) {
+      TEST_CHECK(algorithm == 0);
+      algorithm = HSH_MD5_NONCRYPTO;
+    } else {
+      TEST_CHECK(algorithm != 0);
+    }
+    hash_id = HSH_GetHashId(algorithm);
+    if (hash_id < 0) {
+      TEST_CHECK(algorithm != HSH_MD5_NONCRYPTO);
+      TEST_CHECK(algorithm != HSH_MD5);
+#ifdef FEAT_SECHASH
+      TEST_CHECK(algorithm != HSH_SHA1);
+      TEST_CHECK(algorithm != HSH_SHA256);
+      TEST_CHECK(algorithm != HSH_SHA384);
+      TEST_CHECK(algorithm != HSH_SHA512);
+#endif
+      continue;
+    }
+
+    DEBUG_LOG("testing %s", tests[i].name);
+
+    TEST_CHECK(HSH_Hash(hash_id, data1, -1, NULL, 0, out, sizeof (out)) == 0);
+    TEST_CHECK(HSH_Hash(hash_id, data1, sizeof (data1) - 1, data2, -1, out, sizeof (out)) == 0);
+    TEST_CHECK(HSH_Hash(hash_id, data1, sizeof (data1) - 1, NULL, 0, out, -1) == 0);
+
+    for (j = 0; j <= sizeof (out); j++) {
+      TEST_CHECK(HSH_GetHashId(algorithm) == hash_id);
+      TEST_CHECK(HSH_GetHashId(0) < 0);
+
+      memset(out, 0, sizeof (out));
+      length = HSH_Hash(hash_id, data1, sizeof (data1) - 1, data2, sizeof (data2) - 1,
+                        out, j);
+
+      if (j >= tests[i].length)
+        TEST_CHECK(length == tests[i].length);
+      else
+        TEST_CHECK(length == j);
+
+      TEST_CHECK(!memcmp(out, tests[i].out, length));
+    }
+
+    for (j = 0; j < 10000; j++) {
+      length = HSH_Hash(hash_id, data1, random() % sizeof (data1),
+                        random() % 2 ? data2 : NULL, random() % sizeof (data2),
+                        out, sizeof (out));
+      TEST_CHECK(length == tests[i].length);
+    }
+  }
+
+  HSH_Finalise();
+}
diff --git a/test/unit/hwclock.c b/test/unit/hwclock.c
new file mode 100644
index 0000000..79c0879
--- /dev/null
+++ b/test/unit/hwclock.c
@@ -0,0 +1,117 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+
+#include <hwclock.c>
+
+#define MAX_READINGS 20
+
+void
+test_unit(void)
+{
+  struct timespec start_hw_ts, start_local_ts, hw_ts, local_ts, ts;
+  struct timespec readings[MAX_READINGS][3];
+  HCL_Instance clock;
+  double freq, jitter, interval, dj, err, sum;
+  int i, j, k, l, new_sample, n_readings, count;
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+
+  for (i = 1; i <= 8; i++) {
+    clock = HCL_CreateInstance(random() % (1 << i), 1 << i, 1.0, 1e-9);
+
+    for (j = 0, count = 0, sum = 0.0; j < 100; j++) {
+      UTI_ZeroTimespec(&start_hw_ts);
+      UTI_ZeroTimespec(&start_local_ts);
+      UTI_AddDoubleToTimespec(&start_hw_ts, TST_GetRandomDouble(0.0, 1e9), &start_hw_ts);
+      UTI_AddDoubleToTimespec(&start_local_ts, TST_GetRandomDouble(0.0, 1e9), &start_local_ts);
+
+      DEBUG_LOG("iteration %d", j);
+
+      freq = TST_GetRandomDouble(0.9, 1.1);
+      jitter = TST_GetRandomDouble(10.0e-9, 1000.0e-9);
+      interval = TST_GetRandomDouble(0.1, 10.0);
+
+      clock->n_samples = 0;
+      clock->valid_coefs = 0;
+      QNT_Reset(clock->delay_quants);
+
+      new_sample = 0;
+
+      for (k = 0; k < 100; k++) {
+        UTI_AddDoubleToTimespec(&start_hw_ts, k * interval * freq, &hw_ts);
+        UTI_AddDoubleToTimespec(&start_local_ts, k * interval, &local_ts);
+        if (HCL_CookTime(clock, &hw_ts, &ts, NULL) && new_sample) {
+          dj = fabs(UTI_DiffTimespecsToDouble(&ts, &local_ts) / jitter);
+          DEBUG_LOG("delta/jitter %f", dj);
+          if (clock->n_samples >= clock->max_samples / 2)
+            sum += dj, count++;
+          TEST_CHECK(clock->n_samples < 4 || dj <= 4.0);
+          TEST_CHECK(clock->n_samples < 8 || dj <= 3.0);
+        }
+
+        UTI_AddDoubleToTimespec(&start_hw_ts, k * interval * freq + TST_GetRandomDouble(-jitter, jitter), &hw_ts);
+
+        if (HCL_NeedsNewSample(clock, &local_ts)) {
+          n_readings = random() % MAX_READINGS + 1;
+          for (l = 0; l < n_readings; l++) {
+            UTI_AddDoubleToTimespec(&local_ts, -TST_GetRandomDouble(0.0, jitter / 10.0), &readings[l][0]);
+            readings[l][1] = hw_ts;
+            UTI_AddDoubleToTimespec(&local_ts, TST_GetRandomDouble(0.0, jitter / 10.0), &readings[l][2]);
+          }
+
+          UTI_ZeroTimespec(&hw_ts);
+          UTI_ZeroTimespec(&local_ts);
+          if (HCL_ProcessReadings(clock, n_readings, readings, &hw_ts, &local_ts, &err)) {
+            HCL_AccumulateSample(clock, &hw_ts, &local_ts, 2.0 * jitter);
+            new_sample = 1;
+          } else {
+            new_sample = 0;
+          }
+        }
+
+        TEST_CHECK(clock->valid_coefs == (clock->n_samples >= 2));
+
+        if (!clock->valid_coefs)
+          continue;
+
+        TEST_CHECK(fabs(clock->offset) <= 2.0 * jitter);
+      }
+    }
+
+    TEST_CHECK(sum / count < 2.4 / sqrt(clock->max_samples));
+
+    HCL_DestroyInstance(clock);
+  }
+
+  LCL_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/keys.c b/test/unit/keys.c
new file mode 100644
index 0000000..aa5e649
--- /dev/null
+++ b/test/unit/keys.c
@@ -0,0 +1,173 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_NTP) || defined(FEAT_CMDMON)
+
+#include <keys.c>
+
+#define KEYS 100
+#define KEYFILE "keys.test-keys"
+
+static
+uint32_t write_random_key(FILE *f)
+{
+  const char *type, *prefix;
+  char key[128];
+  uint32_t id;
+  int i, length;
+
+  length = random() % sizeof (key) + 1;
+  length = MAX(length, 4);
+  prefix = random() % 2 ? "HEX:" : "";
+
+  switch (random() % 8) {
+#ifdef FEAT_SECHASH
+    case 0:
+      type = "SHA1";
+      break;
+    case 1:
+      type = "SHA256";
+      break;
+    case 2:
+      type = "SHA384";
+      break;
+    case 3:
+      type = "SHA512";
+      break;
+#endif
+#ifdef HAVE_CMAC
+    case 4:
+      type = "AES128";
+      length = prefix[0] == '\0' ? 8 : 16;
+      break;
+    case 5:
+      type = "AES256";
+      length = prefix[0] == '\0' ? 16 : 32;
+      break;
+#endif
+    case 6:
+      type = "MD5";
+      break;
+    default:
+      type = "";
+  }
+
+  UTI_GetRandomBytes(&id, sizeof (id));
+  UTI_GetRandomBytes(key, length);
+
+  fprintf(f, "%u %s %s", id, type, prefix);
+  for (i = 0; i < length; i++)
+    fprintf(f, "%02hhX", key[i]);
+  fprintf(f, "\n");
+
+  return id;
+}
+
+static void
+generate_key_file(const char *name, uint32_t *keys)
+{
+  FILE *f;
+  int i;
+
+  f = fopen(name, "w");
+  TEST_CHECK(f);
+  for (i = 0; i < KEYS; i++)
+    keys[i] = write_random_key(f);
+  fclose(f);
+}
+
+void
+test_unit(void)
+{
+  int i, j, data_len, auth_len, type, bits;
+  uint32_t keys[KEYS], key;
+  unsigned char data[100], auth[MAX_HASH_LENGTH];
+  char conf[][100] = {
+    "keyfile "KEYFILE
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  generate_key_file(KEYFILE, keys);
+  KEY_Initialise();
+
+  for (i = 0; i < 100; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    if (i) {
+      generate_key_file(KEYFILE, keys);
+      KEY_Reload();
+    }
+
+    UTI_GetRandomBytes(data, sizeof (data));
+
+    for (j = 0; j < KEYS; j++) {
+      TEST_CHECK(KEY_KeyKnown(keys[j]));
+      TEST_CHECK(KEY_GetAuthLength(keys[j]) >= 16);
+
+      data_len = random() % (sizeof (data) + 1);
+      auth_len = KEY_GenerateAuth(keys[j], data, data_len, auth, sizeof (auth));
+      TEST_CHECK(auth_len >= 16);
+
+      TEST_CHECK(KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      if (j > 0 && keys[j - 1] != keys[j])
+        TEST_CHECK(!KEY_CheckAuth(keys[j - 1], data, data_len, auth, auth_len, auth_len));
+
+      auth_len = random() % auth_len + 1;
+      if (auth_len < MAX_HASH_LENGTH)
+        auth[auth_len]++;
+      TEST_CHECK(KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      auth[auth_len - 1]++;
+      TEST_CHECK(!KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      TEST_CHECK(KEY_GetKeyInfo(keys[j], &type, &bits));
+      TEST_CHECK(type > 0 && bits > 0);
+    }
+
+    for (j = 0; j < 1000; j++) {
+      UTI_GetRandomBytes(&key, sizeof (key));
+      if (KEY_KeyKnown(key))
+        continue;
+      TEST_CHECK(!KEY_GetKeyInfo(key, &type, &bits));
+      TEST_CHECK(!KEY_GenerateAuth(key, data, data_len, auth, sizeof (auth)));
+      TEST_CHECK(!KEY_CheckAuth(key, data, data_len, auth, auth_len, auth_len));
+    }
+  }
+
+  unlink(KEYFILE);
+
+  KEY_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_auth.c b/test/unit/ntp_auth.c
new file mode 100644
index 0000000..5f2a9bc
--- /dev/null
+++ b/test/unit/ntp_auth.c
@@ -0,0 +1,289 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <conf.h>
+#include <keys.h>
+#include <local.h>
+#include <ntp_ext.h>
+#include <ntp_signd.h>
+#include <nts_ntp_server.h>
+#include <socket.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <ntp_auth.c>
+
+static void
+prepare_packet(NTP_AuthMode auth_mode, NTP_Packet *packet, NTP_PacketInfo *info, int req)
+{
+  unsigned char buf[64];
+  int i, version;
+  NTP_Mode mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      version = 3;
+      mode = random() % 2 ? (req ? MODE_CLIENT : MODE_SERVER) :
+                            (req ? MODE_ACTIVE : MODE_PASSIVE);
+      break;
+    case NTP_AUTH_NTS:
+      version = 4;
+      mode = req ? MODE_CLIENT : MODE_SERVER;
+      break;
+    default:
+      version = 3 + random() % 2;
+      mode = random() % 2 ? (req ? MODE_CLIENT : MODE_SERVER) :
+                            (req ? MODE_ACTIVE : MODE_PASSIVE);
+      break;
+  }
+
+  memset(packet, 0, sizeof (*packet));
+  memset(info, 0, sizeof (*info));
+  packet->lvm = NTP_LVM(LEAP_Normal, version, mode);
+  info->length = NTP_HEADER_LENGTH;
+  info->version = version;
+  info->mode = mode;
+
+  if (version == 4) {
+    memset(buf, 0, sizeof (buf));
+    for (i = random() % 5; i > 0; i--)
+      TEST_CHECK(NEF_AddField(packet, info, 0, buf, sizeof (buf)));
+  }
+}
+
+static void
+add_dummy_auth(NTP_AuthMode auth_mode, uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  unsigned char buf[64];
+  int len, fill;
+
+  info->auth.mode = auth_mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      switch (auth_mode) {
+        case NTP_AUTH_SYMMETRIC:
+          len = 16 + random() % 2 * 4;
+          fill = 1 + random() % 255;
+          break;
+        case NTP_AUTH_MSSNTP:
+          len = 16;
+          fill = 0;
+          break;
+        case NTP_AUTH_MSSNTP_EXT:
+          len = 68;
+          fill = 0;
+          break;
+        default:
+          assert(0);
+      }
+
+      assert(info->length + 4 + len <= sizeof (*packet));
+
+      *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+      info->auth.mac.key_id = key_id;
+      info->length += 4;
+
+      memset((unsigned char *)packet + info->length, fill, len);
+      info->length += len;
+      break;
+    case NTP_AUTH_NTS:
+      memset(buf, 0, sizeof (buf));
+      TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, buf, sizeof (buf)));
+      break;
+    default:
+      assert(0);
+  }
+}
+
+void
+test_unit(void)
+{
+  int i, j, can_auth_req, can_auth_res;
+  NTP_PacketInfo req_info, res_info;
+  NTP_Packet req, res;
+  NAU_Instance inst;
+  RPT_AuthReport report;
+  NTP_AuthMode mode;
+  IPSockAddr nts_addr;
+  uint32_t key_id, kod;
+  char conf[][100] = {
+    "keyfile ntp_core.keys"
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  KEY_Initialise();
+  NSD_Initialise();
+  NNS_Initialise();
+
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &nts_addr.ip_addr);
+  nts_addr.port = 0;
+
+  for (i = 0; i < 1000; i++) {
+    key_id = INACTIVE_AUTHKEY;
+
+    switch (i % 5) {
+      case 0:
+        inst = NAU_CreateNoneInstance();
+        TEST_CHECK(!NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) == 4);
+        mode = NTP_AUTH_NONE;
+        can_auth_req = 1;
+        can_auth_res = 1;
+        break;
+      case 1:
+        key_id = random() % 7 + 2;
+        inst = NAU_CreateSymmetricInstance(key_id);
+        TEST_CHECK(NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) ==
+                   (KEY_KeyKnown(inst->key_id) && KEY_GetAuthLength(inst->key_id) > 20 ? 3 : 4));
+        mode = NTP_AUTH_SYMMETRIC;
+        can_auth_req = KEY_KeyKnown(key_id);
+        can_auth_res = can_auth_req;
+        break;
+      case 2:
+        inst = NAU_CreateNtsInstance(&nts_addr, "test", 0, 0);
+        TEST_CHECK(NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) == 4);
+        mode = NTP_AUTH_NTS;
+        can_auth_req = 0;
+        can_auth_res = 0;
+        break;
+      case 3:
+        key_id = 1 + random() % 100;
+        inst = NULL;
+        mode = NTP_AUTH_MSSNTP;
+        can_auth_req = 1;
+        can_auth_res = 0;
+        break;
+      case 4:
+        key_id = 1 + random() % 100;
+        inst = NULL;
+        mode = NTP_AUTH_MSSNTP_EXT;
+        can_auth_req = 0;
+        can_auth_res = 0;
+        break;
+      default:
+        assert(0);
+    }
+
+    DEBUG_LOG("iteration %d auth=%d key_id=%d", i, (int)mode, (int)key_id);
+
+    prepare_packet(mode, &req, &req_info, 1);
+
+    if (inst) {
+      TEST_CHECK(inst->mode == mode);
+      TEST_CHECK(inst->key_id == key_id);
+
+      NAU_DumpData(inst);
+      NAU_GetReport(inst, &report);
+      if (random() % 2)
+        NAU_ChangeAddress(inst, &nts_addr.ip_addr);
+
+      if (inst->mode == NTP_AUTH_NTS) {
+        for (j = random() % 5; j > 0; j--)
+#ifdef FEAT_NTS
+          TEST_CHECK(!NAU_PrepareRequestAuth(inst));
+#else
+          TEST_CHECK(NAU_PrepareRequestAuth(inst));
+#endif
+        TEST_CHECK(!NAU_GenerateRequestAuth(inst, &req, &req_info));
+      } else if (can_auth_req) {
+        TEST_CHECK(NAU_PrepareRequestAuth(inst));
+        TEST_CHECK(NAU_GenerateRequestAuth(inst, &req, &req_info));
+      } else {
+        TEST_CHECK(NAU_PrepareRequestAuth(inst));
+        TEST_CHECK(!NAU_GenerateRequestAuth(inst, &req, &req_info));
+      }
+    }
+
+    if (!inst || !can_auth_req)
+      add_dummy_auth(mode, key_id, &req, &req_info);
+
+    assert(req_info.auth.mode == mode);
+    assert(req_info.auth.mac.key_id == key_id);
+
+    kod = 1;
+    TEST_CHECK(NAU_CheckRequestAuth(&req, &req_info, &kod) == can_auth_req);
+    TEST_CHECK(kod == 0);
+
+    if (inst) {
+      for (j = NTP_AUTH_NONE; j <= NTP_AUTH_NTS; j++) {
+        if (j == mode && j == NTP_AUTH_NONE)
+          continue;
+
+        prepare_packet(j, &res, &res_info, 0);
+        add_dummy_auth(j, key_id ? key_id : 1, &res, &res_info);
+
+        TEST_CHECK(res_info.auth.mode == j);
+        TEST_CHECK(!NAU_CheckResponseAuth(inst, &res, &res_info));
+      }
+    }
+
+    prepare_packet(mode, &res, &res_info, 0);
+    TEST_CHECK(NAU_GenerateResponseAuth(&req, &req_info, &res, &res_info, NULL, NULL, kod) ==
+               can_auth_res);
+    if (!can_auth_res)
+      add_dummy_auth(mode, key_id, &res, &res_info);
+
+    assert(res_info.auth.mode == mode);
+    assert(res_info.auth.mac.key_id == key_id);
+
+    if (inst) {
+      if (mode == NTP_AUTH_SYMMETRIC) {
+        res_info.auth.mac.key_id ^= 1;
+        TEST_CHECK(!NAU_CheckResponseAuth(inst, &res, &res_info));
+        res_info.auth.mac.key_id ^= 1;
+      }
+
+      TEST_CHECK(NAU_CheckResponseAuth(inst, &res, &res_info) == can_auth_res);
+
+      NAU_GetReport(inst, &report);
+      NAU_DestroyInstance(inst);
+    }
+  }
+
+  NNS_Finalise();
+  NSD_Finalise();
+  KEY_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_core.c b/test/unit/ntp_core.c
new file mode 100644
index 0000000..875731e
--- /dev/null
+++ b/test/unit/ntp_core.c
@@ -0,0 +1,623 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017-2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <cmdparse.h>
+#include <conf.h>
+#include <keys.h>
+#include <ntp_ext.h>
+#include <ntp_io.h>
+#include <sched.h>
+#include <local.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+static struct timespec current_time;
+static NTP_Packet req_buffer, res_buffer;
+static int req_length, res_length;
+
+#define NIO_OpenServerSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 100 : 0)
+#define NIO_CloseServerSocket(fd) assert(fd == 100)
+#define NIO_OpenClientSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 101 : 0)
+#define NIO_CloseClientSocket(fd) assert(fd == 101)
+#define NIO_IsServerSocket(fd) (fd == 100)
+#define NIO_IsServerSocketOpen() 1
+#define NIO_SendPacket(msg, to, from, len, process_tx) (memcpy(&req_buffer, msg, len), req_length = len, 1)
+#define SCH_AddTimeoutByDelay(delay, handler, arg) (1 ? 102 : (handler(arg), 1))
+#define SCH_AddTimeoutInClass(delay, separation, randomness, class, handler, arg) \
+  add_timeout_in_class(delay, separation, randomness, class, handler, arg)
+#define SCH_RemoveTimeout(id) assert(!id || id == 102)
+#define LCL_ReadRawTime(ts) (*ts = current_time)
+#define LCL_ReadCookedTime(ts, err) do {double *p = err; *ts = current_time; if (p) *p = 0.0;} while (0)
+#define LCL_GetSysPrecisionAsLog() (random() % 10 - 30)
+#define SRC_UpdateReachability(inst, reach)
+#define SRC_ResetReachability(inst)
+
+static SCH_TimeoutID
+add_timeout_in_class(double min_delay, double separation, double randomness,
+                     SCH_TimeoutClass class, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  return 102;
+}
+
+#include <ntp_core.c>
+
+static void
+advance_time(double x)
+{
+  UTI_AddDoubleToTimespec(&current_time, x, &current_time);
+}
+
+static uint32_t
+get_random_key_id(void)
+{
+  uint32_t id;
+
+  do {
+    id = random() % 8 + 2;
+  } while (!KEY_KeyKnown(id));
+
+  return id;
+}
+
+static void
+send_request(NCR_Instance inst)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  uint32_t prev_tx_count;
+
+  prev_tx_count = inst->report.total_tx_count;
+
+  transmit_timeout(inst);
+  TEST_CHECK(!inst->valid_rx);
+  TEST_CHECK(prev_tx_count + 1 == inst->report.total_tx_count);
+
+  advance_time(1e-5);
+
+  if (random() % 2) {
+    local_addr.ip_addr.family = IPADDR_UNSPEC;
+    local_addr.if_index = INVALID_IF_INDEX;
+    local_addr.sock_fd = 101;
+    local_ts.ts = current_time;
+    local_ts.err = 0.0;
+    local_ts.source = NTP_TS_KERNEL;
+
+    NCR_ProcessTxKnown(inst, &local_addr, &local_ts, &req_buffer, req_length);
+  }
+}
+
+static void
+process_request(NTP_Remote_Address *remote_addr)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = 100;
+  local_ts.ts = current_time;
+  local_ts.err = 0.0;
+  local_ts.source = NTP_TS_KERNEL;
+
+  res_length = 0;
+  NCR_ProcessRxUnknown(remote_addr, &local_addr, &local_ts,
+                       &req_buffer, req_length);
+  res_length = req_length;
+  res_buffer = req_buffer;
+
+  advance_time(1e-5);
+
+  if (random() % 2) {
+    local_ts.ts = current_time;
+    NCR_ProcessTxUnknown(remote_addr, &local_addr, &local_ts,
+                         &res_buffer, res_length);
+  }
+}
+
+static void
+send_response(int interleaved, int authenticated, int allow_update, int valid_ts, int valid_auth)
+{
+  NTP_Packet *req, *res;
+  uint32_t key_id = 0;
+  int i, auth_len = 0, ef_len, efs;
+
+  req = &req_buffer;
+  res = &res_buffer;
+
+  TEST_CHECK(req_length >= NTP_HEADER_LENGTH);
+
+  res->lvm = NTP_LVM(LEAP_Normal, NTP_LVM_TO_VERSION(req->lvm),
+                     NTP_LVM_TO_MODE(req->lvm) == MODE_CLIENT ? MODE_SERVER : MODE_ACTIVE);
+  res->stratum = 1;
+  res->poll = req->poll;
+  res->precision = -20;
+  res->root_delay = UTI_DoubleToNtp32(0.1);
+  res->root_dispersion = UTI_DoubleToNtp32(0.1);
+  res->reference_id = 0;
+  UTI_ZeroNtp64(&res->reference_ts);
+  res->originate_ts = interleaved ? req->receive_ts : req->transmit_ts;
+
+  advance_time(TST_GetRandomDouble(1e-4, 1e-2));
+  UTI_TimespecToNtp64(&current_time, &res->receive_ts, NULL);
+  advance_time(TST_GetRandomDouble(-1e-4, 1e-3));
+  UTI_TimespecToNtp64(&current_time, &res->transmit_ts, NULL);
+  advance_time(TST_GetRandomDouble(1e-4, 1e-2));
+
+  if (!valid_ts) {
+    switch (random() % (allow_update ? 4 : 5)) {
+      case 0:
+        res->originate_ts.hi = random();
+        break;
+      case 1:
+        res->originate_ts.lo = random();
+        break;
+      case 2:
+        UTI_ZeroNtp64(&res->originate_ts);
+        break;
+      case 3:
+        UTI_ZeroNtp64(&res->receive_ts);
+        break;
+      case 4:
+        UTI_ZeroNtp64(&res->transmit_ts);
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  res_length = NTP_HEADER_LENGTH;
+
+  if (NTP_LVM_TO_VERSION(res->lvm) == 4 && random() % 2) {
+    unsigned char buf[128];
+
+    memset(buf, 0, sizeof (buf));
+    efs = random() % 5;
+
+    for (i = 0; i < efs; i++) {
+      ef_len = (i + 1 == efs ? NTP_MAX_V4_MAC_LENGTH + 4 : NTP_MIN_EF_LENGTH) +
+               4 * (random() % 10);
+      TEST_CHECK(NEF_SetField((unsigned char *)res, sizeof (*res), res_length, 0,
+                              buf, ef_len - 4, &ef_len));
+      res_length += ef_len;
+    }
+  }
+
+  if (authenticated) {
+    key_id = ntohl(*(uint32_t *)req->extensions);
+    if (key_id == 0)
+      key_id = get_random_key_id();
+    auth_len = KEY_GetAuthLength(key_id);
+    assert(auth_len);
+    if (NTP_LVM_TO_VERSION(res->lvm) == 4)
+      auth_len = MIN(auth_len, NTP_MAX_V4_MAC_LENGTH - 4);
+
+    if (KEY_GenerateAuth(key_id, res, res_length,
+                         (unsigned char *)res + res_length + 4, auth_len) != auth_len)
+      assert(0);
+    res_length += 4 + auth_len;
+  }
+
+  if (!valid_auth && authenticated) {
+    assert(auth_len);
+
+    switch (random() % 5) {
+      case 0:
+        key_id++;
+        break;
+      case 1:
+        key_id ^= 1;
+        if (KEY_GenerateAuth(key_id, res, res_length - auth_len - 4,
+                             (unsigned char *)res + res_length - auth_len, auth_len) != auth_len)
+          assert(0);
+        break;
+      case 2:
+        ((unsigned char *)res)[res_length - auth_len + random() % auth_len]++;
+        break;
+      case 3:
+        res_length -= 4 + auth_len;
+        auth_len = 4 * (random() % (auth_len / 4));
+        res_length += 4 + auth_len;
+        break;
+      case 4:
+        if (NTP_LVM_TO_VERSION(res->lvm) == 4 && random() % 2 &&
+            KEY_GetAuthLength(key_id) > NTP_MAX_V4_MAC_LENGTH - 4) {
+          res_length -= 4 + auth_len;
+          auth_len += 4 + 4 * (random() %
+                               ((KEY_GetAuthLength(key_id) - NTP_MAX_V4_MAC_LENGTH - 4) / 4));
+          if (KEY_GenerateAuth(key_id, res, res_length,
+                               (unsigned char *)res + res_length + 4, auth_len) != auth_len)
+              assert(0);
+          res_length += 4 + auth_len;
+        } else {
+          memset((unsigned char *)res + res_length, 0, 4);
+          auth_len += 4;
+          res_length += 4;
+        }
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  assert(res_length <= sizeof (*res));
+  assert(res_length >= NTP_HEADER_LENGTH + auth_len);
+
+  if (authenticated)
+    *(uint32_t *)((unsigned char *)res + res_length - auth_len - 4) = htonl(key_id);
+}
+
+static void
+proc_response(NCR_Instance inst, int good, int valid, int updated_sync, int updated_init)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  NTP_Packet *res;
+  uint32_t prev_rx_count, prev_valid_count;
+  struct timespec prev_rx_ts, prev_init_rx_ts;
+  int ret;
+
+  res = &res_buffer;
+
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = NTP_LVM_TO_MODE(res->lvm) != MODE_SERVER ? 100 : 101;
+  local_ts.ts = current_time;
+  local_ts.err = 0.0;
+  local_ts.source = NTP_TS_KERNEL;
+
+  prev_rx_count = inst->report.total_rx_count;
+  prev_valid_count = inst->report.total_valid_count;
+  prev_rx_ts = inst->local_rx.ts;
+  prev_init_rx_ts = inst->init_local_rx.ts;
+
+  ret = NCR_ProcessRxKnown(inst, &local_addr, &local_ts, res, res_length);
+
+  if (good > 0)
+    TEST_CHECK(ret);
+  else if (!good)
+    TEST_CHECK(!ret);
+
+  TEST_CHECK(prev_rx_count + 1 == inst->report.total_rx_count);
+
+  if (valid)
+    TEST_CHECK(prev_valid_count + 1 == inst->report.total_valid_count);
+  else
+    TEST_CHECK(prev_valid_count == inst->report.total_valid_count);
+
+  if (updated_sync)
+    TEST_CHECK(UTI_CompareTimespecs(&inst->local_rx.ts, &prev_rx_ts));
+  else
+    TEST_CHECK(!UTI_CompareTimespecs(&inst->local_rx.ts, &prev_rx_ts));
+
+  if (updated_init > 0)
+    TEST_CHECK(UTI_CompareTimespecs(&inst->init_local_rx.ts, &prev_init_rx_ts));
+  else if (!updated_init)
+    TEST_CHECK(!UTI_CompareTimespecs(&inst->init_local_rx.ts, &prev_init_rx_ts));
+
+  if (valid) {
+    TEST_CHECK(UTI_IsZeroTimespec(&inst->init_local_rx.ts));
+    TEST_CHECK(UTI_IsZeroNtp64(&inst->init_remote_ntp_tx));
+  }
+}
+
+static void
+process_replay(NCR_Instance inst, NTP_Packet *packet_queue,
+               int queue_length, int updated_init)
+{
+  do {
+    res_buffer = packet_queue[random() % queue_length];
+  } while (!UTI_CompareNtp64(&res_buffer.transmit_ts, &inst->remote_ntp_tx));
+  proc_response(inst, 0, 0, 0, updated_init);
+  advance_time(1e-6);
+}
+
+static void
+add_dummy_auth(NTP_AuthMode auth_mode, uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  unsigned char buf[64];
+  int len, fill;
+
+  info->auth.mode = auth_mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      switch (auth_mode) {
+        case NTP_AUTH_SYMMETRIC:
+          len = 16 + random() % 2 * 4;
+          fill = 1 + random() % 255;
+          break;
+        case NTP_AUTH_MSSNTP:
+          len = 16;
+          fill = 0;
+          break;
+        case NTP_AUTH_MSSNTP_EXT:
+          len = 68;
+          fill = 0;
+          break;
+        default:
+          assert(0);
+      }
+
+      assert(info->length + 4 + len <= sizeof (*packet));
+
+      *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+      info->auth.mac.key_id = key_id;
+      info->length += 4;
+
+      memset((unsigned char *)packet + info->length, fill, len);
+      info->length += len;
+      break;
+    case NTP_AUTH_NTS:
+      memset(buf, 0, sizeof (buf));
+      TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, buf, sizeof (buf)));
+      break;
+    default:
+      assert(0);
+  }
+}
+
+#define PACKET_QUEUE_LENGTH 10
+
+void
+test_unit(void)
+{
+  char source_line[] = "127.0.0.1 maxdelaydevratio 1e6 noselect";
+  char conf[][100] = {
+    "allow",
+    "port 0",
+    "local",
+    "keyfile ntp_core.keys"
+  };
+  int i, j, k, interleaved, authenticated, valid, updated, has_updated;
+  CPS_NTP_Source source;
+  NTP_Remote_Address remote_addr;
+  NCR_Instance inst1, inst2;
+  NTP_Packet packet_queue[PACKET_QUEUE_LENGTH], packet;
+  NTP_PacketInfo info;
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  REF_Initialise();
+  KEY_Initialise();
+  CLG_Initialise();
+
+  CNF_SetupAccessRestrictions();
+
+  CPS_ParseNTPSourceAdd(source_line, &source);
+
+  for (i = 0; i < 1000; i++) {
+    source.params.interleaved = random() % 2;
+    source.params.authkey = random() % 2 ? get_random_key_id() : INACTIVE_AUTHKEY;
+    source.params.version = random() % 4 + 1;
+
+    UTI_ZeroTimespec(&current_time);
+#if HAVE_LONG_TIME_T
+    advance_time(NTP_ERA_SPLIT);
+#endif
+    advance_time(TST_GetRandomDouble(1.0, 1e9));
+
+    TST_GetRandomAddress(&remote_addr.ip_addr, IPADDR_UNSPEC, -1);
+    remote_addr.port = 123;
+
+    inst1 = NCR_CreateInstance(&remote_addr, random() % 2 ? NTP_SERVER : NTP_PEER,
+                               &source.params, NULL);
+    NCR_StartInstance(inst1);
+    has_updated = 0;
+
+    for (j = 0; j < 50; j++) {
+      DEBUG_LOG("client/peer test iteration %d/%d", i, j);
+
+      interleaved = random() % 2 && (inst1->mode != MODE_CLIENT ||
+                                     inst1->tx_count < MAX_CLIENT_INTERLEAVED_TX);
+      authenticated = random() % 2;
+      valid = (!interleaved || (source.params.interleaved && has_updated)) &&
+              ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
+      updated = (valid || inst1->mode == MODE_ACTIVE) &&
+                ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
+      has_updated = has_updated || updated;
+      if (inst1->mode == MODE_CLIENT)
+        updated = 0;
+
+      DEBUG_LOG("authkey=%d version=%d interleaved=%d authenticated=%d valid=%d updated=%d has_updated=%d",
+                (int)source.params.authkey, source.params.version,
+                interleaved, authenticated, valid, updated, has_updated);
+
+      send_request(inst1);
+
+      send_response(interleaved, authenticated, 1, 0, 1);
+      DEBUG_LOG("response 1");
+      proc_response(inst1, 0, 0, 0, updated);
+
+      if (source.params.authkey) {
+        send_response(interleaved, authenticated, 1, 1, 0);
+        DEBUG_LOG("response 2");
+        proc_response(inst1, 0, 0, 0, 0);
+      }
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 3");
+      proc_response(inst1, -1, valid, valid, updated);
+      DEBUG_LOG("response 4");
+      proc_response(inst1, 0, 0, 0, 0);
+
+      advance_time(-1.0);
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 5");
+      proc_response(inst1, 0, 0, 0, updated && valid);
+
+      advance_time(1.0);
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 6");
+      proc_response(inst1, 0, 0, valid && updated, updated);
+    }
+
+    NCR_DestroyInstance(inst1);
+
+    inst1 = NCR_CreateInstance(&remote_addr, random() % 2 ? NTP_SERVER : NTP_PEER,
+                               &source.params, NULL);
+    NCR_StartInstance(inst1);
+
+    for (j = 0; j < 20; j++) {
+      DEBUG_LOG("server test iteration %d/%d", i, j);
+
+      send_request(inst1);
+      process_request(&remote_addr);
+      proc_response(inst1,
+                    !source.params.interleaved || source.params.version != 4 ||
+                      inst1->mode == MODE_ACTIVE || j != 2,
+                    1, 1, 0);
+      advance_time(1 << inst1->local_poll);
+    }
+
+    NCR_DestroyInstance(inst1);
+
+    inst1 = NCR_CreateInstance(&remote_addr, NTP_PEER, &source.params, NULL);
+    NCR_StartInstance(inst1);
+    inst2 = NCR_CreateInstance(&remote_addr, NTP_PEER, &source.params, NULL);
+    NCR_StartInstance(inst2);
+
+    res_length = req_length = 0;
+
+    for (j = 0; j < 20; j++) {
+      DEBUG_LOG("peer replay test iteration %d/%d", i, j);
+
+      send_request(inst1);
+      res_buffer = req_buffer;
+      assert(!res_length || res_length == req_length);
+      res_length = req_length;
+
+      TEST_CHECK(inst1->valid_timestamps == (j > 0));
+
+      DEBUG_LOG("response 1->2");
+      proc_response(inst2, j > source.params.interleaved, j > 0, j > 0, 1);
+
+      packet_queue[(j * 2) % PACKET_QUEUE_LENGTH] = res_buffer;
+
+      for (k = 0; k < j % 4 + 1; k++) {
+        DEBUG_LOG("replay ?->1 %d", k);
+        process_replay(inst1, packet_queue, MIN(j * 2 + 1, PACKET_QUEUE_LENGTH), k ? -1 : 1);
+        DEBUG_LOG("replay ?->2 %d", k);
+        process_replay(inst2, packet_queue, MIN(j * 2 + 1, PACKET_QUEUE_LENGTH), -1);
+      }
+
+      advance_time(1 << (source.params.minpoll - 1));
+
+      send_request(inst2);
+      res_buffer = req_buffer;
+      assert(res_length == req_length);
+
+      TEST_CHECK(inst2->valid_timestamps == (j > 0));
+
+      DEBUG_LOG("response 2->1");
+      proc_response(inst1, 1, 1, 1, 1);
+
+      packet_queue[(j * 2 + 1) % PACKET_QUEUE_LENGTH] = res_buffer;
+
+      for (k = 0; k < j % 4 + 1; k++) {
+        DEBUG_LOG("replay ?->1 %d", k);
+        process_replay(inst1, packet_queue, MIN(j * 2 + 2, PACKET_QUEUE_LENGTH), k ? -1 : 1);
+        DEBUG_LOG("replay ?->2 %d", k);
+        process_replay(inst2, packet_queue, MIN(j * 2 + 2, PACKET_QUEUE_LENGTH), -1);
+      }
+
+      advance_time(1 << (source.params.minpoll - 1));
+    }
+
+    NCR_DestroyInstance(inst1);
+    NCR_DestroyInstance(inst2);
+  }
+
+  memset(&packet, 0, sizeof (packet));
+  packet.lvm = NTP_LVM(LEAP_Normal, NTP_VERSION, MODE_CLIENT);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_NONE);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_SYMMETRIC, 100, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_SYMMETRIC);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == info.length - NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.key_id == 100);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_NTS, 0, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_NTS);
+
+  packet.lvm = NTP_LVM(LEAP_Normal, 3, MODE_CLIENT);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_MSSNTP, 200, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_MSSNTP);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == 20);
+  TEST_CHECK(info.auth.mac.key_id == 200);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_MSSNTP_EXT, 300, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_MSSNTP_EXT);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == 72);
+  TEST_CHECK(info.auth.mac.key_id == 300);
+
+  CLG_Finalise();
+  KEY_Finalise();
+  REF_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_core.keys b/test/unit/ntp_core.keys
new file mode 100644
index 0000000..a3e4f6c
--- /dev/null
+++ b/test/unit/ntp_core.keys
@@ -0,0 +1,8 @@
+2 MD5 HEX:38979C567358C0896F4D9D459A3C8B8478654579
+3 MD5 HEX:38979C567358C0896F4D9D459A3C8B8478654579
+4 SHA1 HEX:B71744EA01FBF01CA30D173ECDDF901952AE356A
+5 SHA1 HEX:B71744EA01FBF01CA30D173ECDDF901952AE356A
+6 SHA512 HEX:DE027482F22B201FC20863F58C74095E7906089F
+7 SHA512 HEX:DE027482F22B201FC20863F58C74095E7906089F
+8 AES128 HEX:5D5E8A31D4B459A66D445259E147CFB5
+9 AES128 HEX:5D5E8A31D4B459A66D445259E147CFB5
diff --git a/test/unit/ntp_ext.c b/test/unit/ntp_ext.c
new file mode 100644
index 0000000..c37e702
--- /dev/null
+++ b/test/unit/ntp_ext.c
@@ -0,0 +1,167 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <util.h>
+#include <logging.h>
+
+#include <ntp_ext.c>
+
+void
+test_unit(void)
+{
+  unsigned char *buffer, body[NTP_MAX_EXTENSIONS_LENGTH];
+  void *bodyp;
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  int i, j, start, length, type, type2, body_length, body_length2;
+
+  assert(sizeof (uint16_t) == 2);
+  assert(sizeof (body) == sizeof (packet.extensions));
+
+  buffer = (unsigned char *)packet.extensions;
+
+  for (i = 0; i < 10000; i++) {
+    body_length = random() % (sizeof (body) - 4 + 1) / 4 * 4;
+    start = random() % (sizeof (packet.extensions) - body_length - 4 + 1) / 4 * 4;
+    type = random() % 0x10000;
+
+    DEBUG_LOG("body_length=%d start=%d type=%d", body_length, start, type);
+    assert(body_length + start <= sizeof (packet.extensions));
+
+    UTI_GetRandomBytes(body, body_length);
+
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length + 4, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start + 4,
+                             type, body, body_length, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 1, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 2, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 3, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 3, start,
+                             type, body, body_length, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 5, start + 1,
+                             type, body, body_length, &length));
+
+    TEST_CHECK(NEF_SetField(buffer, body_length + start + 4, start,
+                            type, body, body_length, &length));
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(memcmp(buffer + start + 4, body, body_length) == 0);
+
+    memset(&packet, 0, sizeof (packet));
+    packet.lvm = NTP_LVM(0, 4, MODE_CLIENT);
+    memset(&info, 0, sizeof (info));
+
+    info.version = 3;
+    info.length = NTP_HEADER_LENGTH;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.version = 4;
+    info.length = NTP_HEADER_LENGTH - 4;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.length = sizeof (packet) - body_length;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.length = NTP_HEADER_LENGTH + start;
+
+    if (body_length < 12) {
+      TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+      continue;
+    }
+
+    TEST_CHECK(NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+    TEST_CHECK(info.length == NTP_HEADER_LENGTH + start + body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(info.ext_fields == 1);
+
+    memset(buffer, 0, sizeof (packet.extensions));
+    info.length = NTP_HEADER_LENGTH + start;
+    info.ext_fields = 0;
+
+    TEST_CHECK(NEF_AddField(&packet, &info, type, body, body_length));
+    TEST_CHECK(info.length == NTP_HEADER_LENGTH + start + body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(memcmp(buffer + start + 4, body, body_length) == 0);
+    TEST_CHECK(info.ext_fields == 1);
+
+    for (j = 1; j <= 4; j++) {
+      TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] = htons(length + j));
+      TEST_CHECK(!NEF_ParseSingleField(buffer, start + body_length + 4, start,
+                                       &length, &type2, &bodyp, &body_length2));
+    }
+
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] = htons(length));
+
+    TEST_CHECK(NEF_ParseSingleField(buffer, sizeof (packet.extensions), start,
+                                    &length, &type2, &bodyp, &body_length2));
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(type2 == type);
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(body_length2 == body_length);
+
+    TEST_CHECK(!NEF_ParseField(&packet, sizeof (packet) + 4,
+                               NTP_HEADER_LENGTH + start,
+                               &length, &type2, &bodyp, &body_length2));
+
+    if (body_length < 24) {
+      TEST_CHECK(!NEF_ParseField(&packet, NTP_HEADER_LENGTH + start + length, 
+                                 NTP_HEADER_LENGTH + start,
+                                 &length, &type2, &bodyp, &body_length2));
+      if (sizeof (packet.extensions) - start <= 24) {
+        TEST_CHECK(!NEF_ParseField(&packet, sizeof (packet), NTP_HEADER_LENGTH + start,
+                                   &length, &type2, &bodyp, &body_length2));
+        continue;
+      } else {
+        TEST_CHECK(NEF_ParseField(&packet, sizeof (packet), NTP_HEADER_LENGTH + start,
+                                  &length, &type2, &bodyp, &body_length2));
+      }
+    } else {
+      TEST_CHECK(NEF_ParseField(&packet, NTP_HEADER_LENGTH + start + length, 
+                                NTP_HEADER_LENGTH + start,
+                                &length, &type2, &bodyp, &body_length2));
+    }
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(type2 == type);
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(body_length2 == body_length);
+
+  }
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_sources.c b/test/unit/ntp_sources.c
new file mode 100644
index 0000000..ea3910f
--- /dev/null
+++ b/test/unit/ntp_sources.c
@@ -0,0 +1,364 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <conf.h>
+#include <cmdparse.h>
+#include <nameserv_async.h>
+#include <ntp_core.h>
+#include <ntp_io.h>
+
+static char *requested_name = NULL;
+static DNS_NameResolveHandler resolve_handler = NULL;
+static void *resolve_handler_arg = NULL;
+
+#define DNS_Name2IPAddressAsync(name, handler, arg) \
+  requested_name = (name), \
+  resolve_handler = (handler), \
+  resolve_handler_arg = (arg)
+#define NCR_ChangeRemoteAddress(inst, remote_addr, ntp_only) \
+  change_remote_address(inst, remote_addr, ntp_only)
+#define NCR_ProcessRxKnown(remote_addr, local_addr, ts, msg, len) (random() % 2)
+#define NIO_IsServerConnectable(addr) (random() % 2)
+
+static void change_remote_address(NCR_Instance inst, NTP_Remote_Address *remote_addr,
+                                  int ntp_only);
+
+#include <ntp_sources.c>
+
+#undef NCR_ChangeRemoteAddress
+
+static void
+resolve_random_address(DNS_Status status, int rand_bits)
+{
+  IPAddr ip_addrs[DNS_MAX_ADDRESSES];
+  int i, n_addrs;
+
+  TEST_CHECK(requested_name);
+  requested_name = NULL;
+
+  if (status == DNS_Success) {
+    n_addrs = random() % DNS_MAX_ADDRESSES + 1;
+    for (i = 0; i < n_addrs; i++)
+      TST_GetRandomAddress(&ip_addrs[i], IPADDR_UNSPEC, rand_bits);
+  } else {
+    n_addrs = 0;
+  }
+
+  (resolve_handler)(status, n_addrs, ip_addrs, resolve_handler_arg);
+}
+
+static int
+update_random_address(NTP_Remote_Address *addr, int rand_bits)
+{
+  NTP_Remote_Address new_addr;
+  NSR_Status status;
+
+  TST_GetRandomAddress(&new_addr.ip_addr, IPADDR_UNSPEC, rand_bits);
+  new_addr.port = random() % 1024;
+
+  status = NSR_UpdateSourceNtpAddress(addr, &new_addr);
+  if (status == NSR_InvalidAF) {
+    TEST_CHECK(!UTI_IsIPReal(&addr->ip_addr));
+  } else {
+    TEST_CHECK(status == NSR_Success || status == NSR_AlreadyInUse);
+  }
+
+  return status == NSR_Success;
+}
+
+static void
+change_remote_address(NCR_Instance inst, NTP_Remote_Address *remote_addr, int ntp_only)
+{
+  int update = !ntp_only && random() % 4 == 0, update_pos = random() % 2, r = 0;
+
+  TEST_CHECK(record_lock);
+
+  if (update && update_pos == 0)
+    r = update_random_address(remote_addr, 4);
+
+  NCR_ChangeRemoteAddress(inst, remote_addr, ntp_only);
+
+  if (update && update_pos == 1)
+    r = update_random_address(remote_addr, 4);
+
+  if (r)
+    TEST_CHECK(UTI_IsIPReal(&saved_address_update.old_address.ip_addr));
+}
+
+void
+test_unit(void)
+{
+  char source_line[] = "127.0.0.1 offline", conf[] = "port 0", name[64];
+  int i, j, k, slot, found, pool, prev_n;
+  uint32_t hash = 0, conf_id;
+  NTP_Remote_Address addrs[256], addr;
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  struct UnresolvedSource *us;
+  RPT_ActivityReport report;
+  CPS_NTP_Source source;
+  NSR_Status status;
+  NTP_Packet msg;
+
+  CNF_Initialise(0, 0);
+  CNF_ParseLine(NULL, 1, conf);
+
+  PRV_Initialise();
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  REF_Initialise();
+  NSR_Initialise();
+
+  CPS_ParseNTPSourceAdd(source_line, &source);
+
+  TEST_CHECK(n_sources == 0);
+
+  for (i = 0; i < 6; i++) {
+    TEST_CHECK(ARR_GetSize(records) == 1);
+
+    DEBUG_LOG("collision mod %u", 1U << i);
+
+    for (j = 0; j < sizeof (addrs) / sizeof (addrs[0]); j++) {
+      while (1) {
+        do {
+          TST_GetRandomAddress(&addrs[j].ip_addr, IPADDR_UNSPEC, -1);
+        } while (UTI_IPToHash(&addrs[j].ip_addr) % (1U << i) != hash % (1U << i));
+
+        for (k = 0; k < j; k++)
+          if (UTI_CompareIPs(&addrs[k].ip_addr, &addrs[j].ip_addr, NULL) == 0)
+            break;
+        if (k == j)
+          break;
+      }
+
+      addrs[j].port = random() % 1024;
+
+      if (!j)
+        hash = UTI_IPToHash(&addrs[j].ip_addr);
+
+      DEBUG_LOG("adding source %s hash %"PRIu32, UTI_IPToString(&addrs[j].ip_addr),
+                UTI_IPToHash(&addrs[j].ip_addr) % (1U << i));
+
+      status = NSR_AddSource(&addrs[j], random() % 2 ? NTP_SERVER : NTP_PEER,
+                             &source.params, NULL);
+      TEST_CHECK(status == NSR_Success);
+      TEST_CHECK(n_sources == j + 1);
+
+      TEST_CHECK(strcmp(NSR_GetName(&addrs[j].ip_addr), UTI_IPToString(&addrs[j].ip_addr)) == 0);
+
+      for (k = 0; k <= j; k++) {
+        addr = addrs[k];
+        found = find_slot2(&addr, &slot);
+        TEST_CHECK(found == 2);
+        TEST_CHECK(!UTI_CompareIPs(&get_record(slot)->remote_addr->ip_addr,
+                                   &addr.ip_addr, NULL));
+        addr.port++;
+        found = find_slot2(&addr, &slot);
+        TEST_CHECK(found == 1);
+        TEST_CHECK(!UTI_CompareIPs(&get_record(slot)->remote_addr->ip_addr,
+                                   &addr.ip_addr, NULL));
+      }
+
+      status = NSR_AddSource(&addrs[j], NTP_SERVER, &source.params, &conf_id);
+      TEST_CHECK(status == NSR_AlreadyInUse);
+    }
+
+    for (j = 0; j < sizeof (addrs) / sizeof (addrs[0]); j++) {
+      DEBUG_LOG("removing source %s", UTI_IPToString(&addrs[j].ip_addr));
+      NSR_RemoveSource(&addrs[j].ip_addr);
+
+      for (k = 0; k < sizeof (addrs) / sizeof (addrs[0]); k++) {
+        found = find_slot2(&addrs[k], &slot);
+        TEST_CHECK(found == (k <= j ? 0 : 2));
+      }
+    }
+  }
+
+  TEST_CHECK(n_sources == 0);
+
+  status = NSR_AddSourceByName("a b", 0, 0, 0, &source.params, &conf_id);
+  TEST_CHECK(status == NSR_InvalidName);
+
+  local_addr.ip_addr.family = IPADDR_INET4;
+  local_addr.ip_addr.addr.in4 = 0;
+  local_addr.if_index = -1;
+  local_addr.sock_fd = 0;
+  memset(&local_ts, 0, sizeof (local_ts));
+
+  for (i = 0; i < 500; i++) {
+    for (j = 0; j < 20; j++) {
+      snprintf(name, sizeof (name), "ntp%d.example.net", (int)(random() % 10));
+      pool = random() % 2;
+      prev_n = n_sources;
+
+      DEBUG_LOG("%d/%d adding source %s pool=%d", i, j, name, pool);
+      status = NSR_AddSourceByName(name, 0, pool, random() % 2 ? NTP_SERVER : NTP_PEER,
+                                   &source.params, &conf_id);
+      TEST_CHECK(status == NSR_UnresolvedName);
+
+      TEST_CHECK(n_sources == prev_n + (pool ? source.params.max_sources * 2 : 1));
+      TEST_CHECK(unresolved_sources);
+
+      for (us = unresolved_sources; us->next; us = us->next)
+        ;
+      TEST_CHECK(strcmp(us->name, name) == 0);
+      if (pool) {
+        TEST_CHECK(us->address.ip_addr.family == IPADDR_UNSPEC && us->pool_id >= 0);
+      } else {
+        TEST_CHECK(strcmp(NSR_GetName(&us->address.ip_addr), name) == 0);
+        TEST_CHECK(find_slot2(&us->address, &slot) == 2);
+      }
+
+      if (random() % 2) {
+        if (!resolving_id || random() % 2) {
+          NSR_ResolveSources();
+        } else {
+          SCH_RemoveTimeout(resolving_id);
+          resolve_sources_timeout(NULL);
+          TEST_CHECK(resolving_id == 0);
+          TEST_CHECK(requested_name);
+        }
+
+        TEST_CHECK(!!unresolved_sources == (resolving_id != 0) || requested_name);
+      }
+
+      while (requested_name && random() % 2) {
+        TEST_CHECK(resolving_source);
+        TEST_CHECK(strcmp(requested_name, resolving_source->name) == 0);
+        TEST_CHECK(!record_lock);
+
+        switch (random() % 3) {
+          case 0:
+            resolve_random_address(DNS_Success, 4);
+            break;
+          case 1:
+            resolve_random_address(DNS_TryAgain, 0);
+            break;
+          case 2:
+            resolve_random_address(DNS_Failure, 0);
+            break;
+        }
+      }
+
+      while (random() % 8 > 0) {
+        slot = random() % ARR_GetSize(records);
+        if (!get_record(slot)->remote_addr)
+          continue;
+
+        switch (random() % 5) {
+          case 0:
+            msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
+            NSR_ProcessTx(get_record(slot)->remote_addr, &local_addr,
+                          &local_ts, &msg, 0);
+            break;
+          case 1:
+            msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
+            NSR_ProcessRx(get_record(slot)->remote_addr, &local_addr,
+                          &local_ts, &msg, 0);
+            break;
+          case 2:
+            NSR_HandleBadSource(&get_record(slot)->remote_addr->ip_addr);
+            break;
+          case 3:
+            NSR_SetConnectivity(NULL, &get_record(slot)->remote_addr->ip_addr, SRC_OFFLINE);
+            break;
+          case 4:
+            update_random_address(get_record(slot)->remote_addr, 4);
+            TEST_CHECK(!UTI_IsIPReal(&saved_address_update.old_address.ip_addr));
+            break;
+        }
+
+        TEST_CHECK(!record_lock);
+      }
+
+      NSR_GetActivityReport(&report);
+      TEST_CHECK(report.online == 0);
+      TEST_CHECK(report.offline >= 0);
+      TEST_CHECK(report.burst_online == 0);
+      TEST_CHECK(report.burst_offline == 0);
+      TEST_CHECK(report.unresolved >= 0);
+
+      if (random() % 4 == 0) {
+        NSR_RemoveSourcesById(conf_id);
+        TEST_CHECK(n_sources <= prev_n);
+      } else if (random() % 8 == 0) {
+        NSR_RefreshAddresses();
+        TEST_CHECK(unresolved_sources);
+      }
+    }
+
+    NSR_RemoveAllSources();
+    TEST_CHECK(n_sources == 0);
+
+    for (j = 0; j < ARR_GetSize(pools); j++) {
+      TEST_CHECK(get_pool(j)->sources == 0);
+      TEST_CHECK(get_pool(j)->unresolved_sources == 0);
+      TEST_CHECK(get_pool(j)->confirmed_sources == 0);
+      TEST_CHECK(get_pool(j)->max_sources == 0);
+    }
+
+    while (requested_name) {
+      TEST_CHECK(resolving_source);
+      resolve_random_address(random() % 2 ? DNS_Success : DNS_TryAgain, 4);
+    }
+
+    if (unresolved_sources && resolving_id == 0)
+      NSR_ResolveSources();
+
+    TEST_CHECK(!!unresolved_sources == (resolving_id != 0));
+
+    if (resolving_id) {
+      SCH_RemoveTimeout(resolving_id);
+      resolve_sources_timeout(NULL);
+    }
+
+    TEST_CHECK(resolving_id == 0);
+    TEST_CHECK(!requested_name);
+    TEST_CHECK(!unresolved_sources);
+  }
+
+  NSR_Finalise();
+  REF_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke.crt b/test/unit/nts_ke.crt
new file mode 100644
index 0000000..8165287
--- /dev/null
+++ b/test/unit/nts_ke.crt
@@ -0,0 +1,8 @@
+-----BEGIN CERTIFICATE-----
+MIIBDjCBwaADAgECAgEBMAUGAytlcDAPMQ0wCwYDVQQDEwR0ZXN0MCAXDTcwMDEw
+MTAwMDAwMFoYDzIxMDAwMTAyMDAwMDAwWjAPMQ0wCwYDVQQDEwR0ZXN0MCowBQYD
+K2VwAyEA3oh/FZeOxRYvJVLfCDEwGI6Oe23gTgLHx8a87tvwgfyjQDA+MAwGA1Ud
+EwEB/wQCMAAwDwYDVR0PAQH/BAUDAweAADAdBgNVHQ4EFgQUYwAqF9q3jxUk68m1
+cuz8DueOHeMwBQYDK2VwA0EAne0dCRXb0dW8bn2v3RhVTqeTJWXfl74x8MTQMTM7
+/uGTqoYOA0YJffypd+p27pvx2BEoNQWRYM6pqBg55KbwDw==
+-----END CERTIFICATE-----
diff --git a/test/unit/nts_ke.key b/test/unit/nts_ke.key
new file mode 100644
index 0000000..6414c64
--- /dev/null
+++ b/test/unit/nts_ke.key
@@ -0,0 +1,25 @@
+Public Key Info:
+	Public Key Algorithm: EdDSA (Ed25519)
+	Key Security Level: High (256 bits)
+
+curve:	Ed25519
+private key:
+	01:d9:75:42:7c:52:cc:29:9e:90:01:f3:da:26:f6:d7
+	ad:af:a5:2a:82:36:1d:86:c6:57:a7:b4:99:9b:6c:6d
+	
+
+x:
+	de:88:7f:15:97:8e:c5:16:2f:25:52:df:08:31:30:18
+	8e:8e:7b:6d:e0:4e:02:c7:c7:c6:bc:ee:db:f0:81:fc
+	
+
+
+Public Key PIN:
+	pin-sha256:C4LBJP2cRxvLcZ6pjowcOEQhcW3ZPMVTpLgRGsBDeMw=
+Public Key ID:
+	sha256:0b82c124fd9c471bcb719ea98e8c1c384421716dd93cc553a4b8111ac04378cc
+	sha1:63002a17dab78f1524ebc9b572ecfc0ee78e1de3
+
+-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIAHZdUJ8UswpnpAB89om9tetr6UqgjYdhsZXp7SZm2xt
+-----END PRIVATE KEY-----
diff --git a/test/unit/nts_ke_client.c b/test/unit/nts_ke_client.c
new file mode 100644
index 0000000..72690bf
--- /dev/null
+++ b/test/unit/nts_ke_client.c
@@ -0,0 +1,144 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ke_client.c>
+#include <local.h>
+
+static void
+prepare_response(NKSN_Instance session, int valid)
+{
+  uint16_t data[16];
+  int i, index, length;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 10;
+  DEBUG_LOG("index=%d", index);
+
+  NKSN_BeginMessage(session);
+
+  memset(data, 0, sizeof (data));
+  length = 2;
+  assert(sizeof (data[0]) == 2);
+
+  if (index == 0) {
+    data[0] = htons(random() % 100);
+    TEST_CHECK(NKSN_AddRecord(session, 1, random() % 2 ? NKE_RECORD_ERROR : NKE_RECORD_WARNING,
+                              data, length));
+  } else if (index == 1) {
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_ERROR + 1000, data, length));
+  }
+
+  if (index != 2) {
+    if (index == 3)
+      data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4 + random() % 10 + 1);
+    else
+      data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+    if (index == 4)
+      length = 3 + random() % 10;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+  }
+
+  if (index != 5) {
+    if (index == 6)
+      data[0] = htons(AEAD_AES_SIV_CMAC_256 + random() % 10 + 1);
+    else
+      data[0] = htons(AEAD_AES_SIV_CMAC_256);
+    if (index == 7)
+      length = 3 + random() % 10;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+  }
+
+  if (random() % 2) {
+    const char server[] = "127.0.0.1";
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                              server, sizeof (server) - 1));
+  }
+
+  if (random() % 2) {
+    data[0] = htons(123);
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_PORT_NEGOTIATION, data, length));
+  }
+
+  if (random() % 2) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 0, 1000 + random() % 1000, data, length));
+  }
+
+  if (index != 8) {
+    for (i = 0; i < NKE_MAX_COOKIES; i++) {
+      length = (random() % sizeof (data) + 1) / 4 * 4;
+      if (index == 9)
+        length += (length < sizeof (data) ? 1 : -1) * (random() % 3 + 1);
+      TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_COOKIE, data, length));
+    }
+  }
+
+  TEST_CHECK(NKSN_EndMessage(session));
+}
+
+void
+test_unit(void)
+{
+  NKC_Instance inst;
+  IPSockAddr addr;
+  int i, r, valid;
+
+  char conf[][100] = {
+    "nosystemcert",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+
+  SCK_GetLoopbackIPAddress(AF_INET, &addr.ip_addr);
+  addr.port = 0;
+
+  inst = NKC_CreateInstance(&addr, "test", 0);
+  TEST_CHECK(inst);
+
+  for (i = 0; i < 10000; i++) {
+    valid = random() % 2;
+    prepare_response(inst->session, valid);
+    r = process_response(inst);
+    TEST_CHECK(r == valid);
+  }
+
+  NKC_DestroyInstance(inst);
+
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke_server.c b/test/unit/nts_ke_server.c
new file mode 100644
index 0000000..f4f03a1
--- /dev/null
+++ b/test/unit/nts_ke_server.c
@@ -0,0 +1,230 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <local.h>
+#include <nts_ke_session.h>
+#include <util.h>
+
+#define NKSN_GetKeys get_keys
+
+static int
+get_keys(NKSN_Instance session, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c)
+{
+  c2s->length = SIV_GetKeyLength(siv);
+  UTI_GetRandomBytes(c2s->key, c2s->length);
+  s2c->length = SIV_GetKeyLength(siv);
+  UTI_GetRandomBytes(s2c->key, s2c->length);
+  return 1;
+}
+
+#include <nts_ke_server.c>
+
+static void
+prepare_request(NKSN_Instance session, int valid)
+{
+  uint16_t data[16];
+  int index, length;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 9;
+  DEBUG_LOG("index=%d", index);
+
+  NKSN_BeginMessage(session);
+
+  memset(data, 0, sizeof (data));
+  length = 2;
+  assert(sizeof (data[0]) == 2);
+
+  if (index != 0) {
+    memset(data, NKE_NEXT_PROTOCOL_NTPV4 + 1, sizeof (data));
+    data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+    if (index == 1)
+      length = 0;
+    else if (index == 2)
+      length = 3 + random() % 15 * 2;
+    else
+      length = 2 + random() % 16 * 2;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+  }
+
+  if (index == 3)
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+
+  if (index != 4) {
+    data[0] = htons(AEAD_AES_SIV_CMAC_256);
+    if (index == 5)
+      length = 0;
+    else if (index == 6)
+      length = 3 + random() % 15 * 2;
+    else
+      length = 2 + random() % 16 * 2;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+  }
+
+  if (index == 7)
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+
+  if (index == 8) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 1, 1000 + random() % 1000, data, length));
+  }
+
+  if (random() % 2) {
+    const char server[] = "127.0.0.1";
+    TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                              server, sizeof (server) - 1));
+  }
+
+  if (random() % 2) {
+    data[0] = htons(123);
+    TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_NTPV4_PORT_NEGOTIATION, data, length));
+  }
+
+  if (random() % 2) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 0, 1000 + random() % 1000, data, length));
+  }
+
+  TEST_CHECK(NKSN_EndMessage(session));
+}
+
+static void
+process_response(NKSN_Instance session, int valid)
+{
+  int records, errors, critical, type, length;
+
+  for (records = errors = 0; ; records++) {
+    if (!NKSN_GetRecord(session, &critical, &type, &length, NULL, 0))
+      break;
+    if (type == NKE_RECORD_ERROR)
+      errors++;
+  }
+
+  if (valid) {
+    TEST_CHECK(records >= 2);
+  } else {
+    TEST_CHECK(records == 1);
+    TEST_CHECK(errors == 1);
+  }
+}
+
+void
+test_unit(void)
+{
+  NKSN_Instance session;
+  NKE_Context context, context2;
+  NKE_Cookie cookie;
+  int i, valid, l;
+  uint32_t sum, sum2;
+
+  char conf[][100] = {
+    "ntsdumpdir .",
+    "ntsport 0",
+    "ntsprocesses 0",
+    "ntsserverkey nts_ke.key",
+    "ntsservercert nts_ke.crt",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+
+  unlink("ntskeys");
+  NKS_PreInitialise(0, 0, 0);
+  NKS_Initialise();
+
+  session = NKSN_CreateInstance(1, NULL, handle_message, NULL);
+
+  for (i = 0; i < 10000; i++) {
+    valid = random() % 2;
+    prepare_request(session, valid);
+    TEST_CHECK(process_request(session));
+    process_response(session, valid);
+  }
+
+
+  for (i = 0; i < 10000; i++) {
+    context.algorithm = AEAD_AES_SIV_CMAC_256;
+    get_keys(session, context.algorithm, &context.c2s, &context.s2c);
+    memset(&cookie, 0, sizeof (cookie));
+    TEST_CHECK(NKS_GenerateCookie(&context, &cookie));
+    TEST_CHECK(NKS_DecodeCookie(&cookie, &context2));
+    TEST_CHECK(context.algorithm == context2.algorithm);
+    TEST_CHECK(context.c2s.length == context2.c2s.length);
+    TEST_CHECK(context.s2c.length == context2.s2c.length);
+    TEST_CHECK(memcmp(context.c2s.key, context2.c2s.key, context.c2s.length) == 0);
+    TEST_CHECK(memcmp(context.s2c.key, context2.s2c.key, context.s2c.length) == 0);
+
+    if (random() % 4) {
+      cookie.cookie[random() % (cookie.length)]++;
+    } else if (random() % 4) {
+      generate_key(current_server_key);
+    } else {
+      l = cookie.length;
+      while (l == cookie.length)
+        cookie.length = random() % (sizeof (cookie.cookie) + 1);
+    }
+    TEST_CHECK(!NKS_DecodeCookie(&cookie, &context2));
+  }
+
+  unlink("ntskeys");
+  save_keys();
+
+  for (i = 0, sum = 0; i < MAX_SERVER_KEYS; i++) {
+    sum += server_keys[i].id + server_keys[i].key[0];
+    generate_key(i);
+  }
+
+  load_keys();
+  TEST_CHECK(unlink("ntskeys") == 0);
+
+  for (i = 0, sum2 = 0; i < MAX_SERVER_KEYS; i++) {
+    sum2 += server_keys[i].id + server_keys[i].key[0];
+  }
+
+  TEST_CHECK(sum == sum2);
+
+  NKSN_DestroyInstance(session);
+
+  NKS_Finalise();
+  TEST_CHECK(unlink("ntskeys") == 0);
+
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke_session.c b/test/unit/nts_ke_session.c
new file mode 100644
index 0000000..d0e72c7
--- /dev/null
+++ b/test/unit/nts_ke_session.c
@@ -0,0 +1,224 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ke_session.c>
+
+#include <local.h>
+#include <socket.h>
+#include <sched.h>
+
+static NKSN_Instance client, server;
+static unsigned char record[NKE_MAX_MESSAGE_LENGTH];
+static int record_length, critical, type_start, records;
+static int request_received;
+static int response_received;
+
+static void
+send_message(NKSN_Instance inst)
+{
+  int i;
+
+  record_length = random() % (NKE_MAX_MESSAGE_LENGTH - 4 + 1);
+  for (i = 0; i < record_length; i++)
+    record[i] = random() % 256;
+  critical = random() % 2;
+  type_start = random() % 30000 + 1;
+  assert(sizeof (struct RecordHeader) == 4);
+  records = random() % ((NKE_MAX_MESSAGE_LENGTH - 4) / (4 + record_length) + 1);
+
+  DEBUG_LOG("critical=%d type_start=%d records=%d*%d",
+            critical, type_start, records, record_length);
+
+  NKSN_BeginMessage(inst);
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(!check_message_format(&inst->message, 1));
+
+  TEST_CHECK(!NKSN_AddRecord(inst, 0, 1, record, NKE_MAX_MESSAGE_LENGTH - 4 + 1));
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(!check_message_format(&inst->message, 1));
+
+  for (i = 0; i < records; i++) {
+    TEST_CHECK(NKSN_AddRecord(inst, critical, type_start + i, record, record_length));
+    TEST_CHECK(!NKSN_AddRecord(inst, 0, 1, &record,
+                               NKE_MAX_MESSAGE_LENGTH - inst->message.length - 4 + 1));
+
+    TEST_CHECK(check_message_format(&inst->message, 0));
+    TEST_CHECK(!check_message_format(&inst->message, 1));
+  }
+
+  TEST_CHECK(NKSN_EndMessage(inst));
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(check_message_format(&inst->message, 1));
+}
+
+static void
+verify_message(NKSN_Instance inst)
+{
+  unsigned char buffer[NKE_MAX_MESSAGE_LENGTH];
+  int i, c, t, length, buffer_length, msg_length, prev_parsed;
+  NKE_Key c2s, s2c;
+
+  for (i = 0; i < records; i++) {
+    memset(buffer, 0, sizeof (buffer));
+    buffer_length = random() % (record_length + 1);
+    assert(buffer_length <= sizeof (buffer));
+
+    prev_parsed = inst->message.parsed;
+    msg_length = inst->message.length;
+
+    TEST_CHECK(NKSN_GetRecord(inst, &c, &t, &length, buffer, buffer_length));
+    TEST_CHECK(c == critical);
+    TEST_CHECK(t == type_start + i);
+    TEST_CHECK(length == record_length);
+    TEST_CHECK(memcmp(record, buffer, buffer_length) == 0);
+    if (buffer_length < record_length)
+      TEST_CHECK(buffer[buffer_length] == 0);
+
+    inst->message.length = inst->message.parsed - 1;
+    inst->message.parsed = prev_parsed;
+    TEST_CHECK(!get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+    TEST_CHECK(inst->message.parsed == prev_parsed);
+    inst->message.length = msg_length;
+    if (msg_length < 0x8000) {
+      inst->message.data[prev_parsed + 2] ^= 0x80;
+      TEST_CHECK(!get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+      TEST_CHECK(inst->message.parsed == prev_parsed);
+      inst->message.data[prev_parsed + 2] ^= 0x80;
+    }
+    TEST_CHECK(get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+    TEST_CHECK(inst->message.parsed > prev_parsed);
+  }
+
+  TEST_CHECK(!NKSN_GetRecord(inst, &critical, &t, &length, buffer, sizeof (buffer)));
+
+  TEST_CHECK(NKSN_GetKeys(inst, AEAD_AES_SIV_CMAC_256, &c2s, &s2c));
+  TEST_CHECK(c2s.length == SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256));
+  TEST_CHECK(s2c.length == SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256));
+}
+
+static int
+handle_request(void *arg)
+{
+  NKSN_Instance server = arg;
+
+  verify_message(server);
+
+  request_received = 1;
+
+  send_message(server);
+
+  return 1;
+}
+
+static int
+handle_response(void *arg)
+{
+  NKSN_Instance client = arg;
+
+  response_received = 1;
+
+  verify_message(client);
+
+  return 1;
+}
+
+static void
+check_finished(void *arg)
+{
+  DEBUG_LOG("checking for stopped sessions");
+  if (!NKSN_IsStopped(server) || !NKSN_IsStopped(client)) {
+    SCH_AddTimeoutByDelay(0.001, check_finished, NULL);
+    return;
+  }
+
+  SCH_QuitProgram();
+}
+
+void
+test_unit(void)
+{
+  NKSN_Credentials client_cred, server_cred;
+  const char *cert, *key;
+  int sock_fds[2], i;
+  uint32_t cert_id;
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+
+  cert = "nts_ke.crt";
+  key = "nts_ke.key";
+  cert_id = 0;
+
+  for (i = 0; i < 50; i++) {
+    SCH_Initialise();
+
+    server = NKSN_CreateInstance(1, NULL, handle_request, NULL);
+    client = NKSN_CreateInstance(0, "test", handle_response, NULL);
+
+    server_cred = NKSN_CreateServerCertCredentials(&cert, &key, 1);
+    client_cred = NKSN_CreateClientCertCredentials(&cert, &cert_id, 1, 0);
+
+    TEST_CHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, sock_fds) == 0);
+    TEST_CHECK(fcntl(sock_fds[0], F_SETFL, O_NONBLOCK) == 0);
+    TEST_CHECK(fcntl(sock_fds[1], F_SETFL, O_NONBLOCK) == 0);
+
+    TEST_CHECK(NKSN_StartSession(server, sock_fds[0], "client", server_cred, 4.0));
+    TEST_CHECK(NKSN_StartSession(client, sock_fds[1], "server", client_cred, 4.0));
+
+    send_message(client);
+
+    request_received = response_received = 0;
+
+    check_finished(NULL);
+
+    SCH_MainLoop();
+
+    TEST_CHECK(NKSN_IsStopped(server));
+    TEST_CHECK(NKSN_IsStopped(client));
+
+    TEST_CHECK(request_received);
+    TEST_CHECK(response_received);
+
+    NKSN_DestroyInstance(server);
+    NKSN_DestroyInstance(client);
+
+    NKSN_DestroyCertCredentials(server_cred);
+    NKSN_DestroyCertCredentials(client_cred);
+
+    SCH_Finalise();
+  }
+
+  LCL_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_auth.c b/test/unit/nts_ntp_auth.c
new file mode 100644
index 0000000..307b93b
--- /dev/null
+++ b/test/unit/nts_ntp_auth.c
@@ -0,0 +1,112 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ntp_auth.c>
+
+#include "ntp_ext.h"
+#include "siv.h"
+
+void
+test_unit(void)
+{
+  unsigned char key[SIV_MAX_KEY_LENGTH], nonce[256], plaintext[256], plaintext2[256];
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  SIV_Instance siv;
+  int i, j, r, packet_length, nonce_length, key_length;
+  int plaintext_length, plaintext2_length, min_ef_length;
+
+  siv = SIV_CreateInstance(AEAD_AES_SIV_CMAC_256);
+  TEST_CHECK(siv);
+
+  for (i = 0; i < 10000; i++) {
+    key_length = SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256);
+    for (j = 0; j < key_length; j++)
+      key[j] = random() % 256;
+    TEST_CHECK(SIV_SetKey(siv, key, key_length));
+
+    nonce_length = random() % sizeof (nonce) + 1;
+    for (j = 0; j < nonce_length; j++)
+      nonce[j] = random() % 256;
+
+    plaintext_length = random() % (sizeof (plaintext) + 1);
+    for (j = 0; j < plaintext_length; j++)
+      plaintext[j] = random() % 256;
+
+    packet_length = NTP_HEADER_LENGTH + random() % 100 * 4;
+    min_ef_length = random() % (sizeof (packet) - packet_length);
+
+    memset(&packet, 0, sizeof (packet));
+    packet.lvm = NTP_LVM(0, 4, 0);
+    memset(&info, 0, sizeof (info));
+    info.version = 4;
+    info.length = packet_length;
+
+    DEBUG_LOG("packet_length=%d nonce_length=%d plaintext_length=%d min_ef_length=%d",
+              packet_length, nonce_length, plaintext_length, min_ef_length);
+
+    r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                           -1, 0);
+    TEST_CHECK(!r);
+    r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, 0, plaintext,
+                           plaintext_length, 0);
+    TEST_CHECK(!r);
+    r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                           plaintext_length, sizeof (packet) - info.length + 1);
+    TEST_CHECK(!r);
+
+    r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                           plaintext_length, min_ef_length);
+    TEST_CHECK(r);
+    TEST_CHECK(info.length - packet_length >= min_ef_length);
+
+    r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                          -1, &plaintext2_length);
+    TEST_CHECK(!r);
+
+    r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                          sizeof (plaintext2), &plaintext2_length);
+    TEST_CHECK(r);
+    TEST_CHECK(plaintext_length == plaintext2_length);
+    TEST_CHECK(memcmp(plaintext, plaintext2, plaintext_length) == 0);
+
+    j = random() % (packet_length + plaintext_length +
+                    nonce_length + SIV_GetTagLength(siv) + 8) / 4 * 4;
+    ((unsigned char *)&packet)[j]++;
+    r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                          sizeof (plaintext2), &plaintext2_length);
+    TEST_CHECK(!r);
+    ((unsigned char *)&packet)[j]--;
+  }
+
+  SIV_DestroyInstance(siv);
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_client.c b/test/unit/nts_ntp_client.c
new file mode 100644
index 0000000..c14fd41
--- /dev/null
+++ b/test/unit/nts_ntp_client.c
@@ -0,0 +1,284 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include "socket.h"
+#include "ntp.h"
+#include "nts_ke_client.h"
+
+#define NKC_CreateInstance(address, name, cert_set) Malloc(1)
+#define NKC_DestroyInstance(inst) Free(inst)
+#define NKC_Start(inst) (random() % 2)
+#define NKC_IsActive(inst) (random() % 2)
+#define NKC_GetRetryFactor(inst) (1)
+
+static int get_nts_data(NKC_Instance inst, NKE_Context *context,
+                        NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+                        IPSockAddr *ntp_address);
+#define NKC_GetNtsData get_nts_data
+
+#include <nts_ntp_client.c>
+
+static int
+get_nts_data(NKC_Instance inst, NKE_Context *context,
+             NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+             IPSockAddr *ntp_address)
+{
+  int i;
+
+  if (random() % 2)
+    return 0;
+
+  context->algorithm = AEAD_AES_SIV_CMAC_256;
+
+  context->c2s.length = SIV_GetKeyLength(context->algorithm);
+  UTI_GetRandomBytes(context->c2s.key, context->c2s.length);
+  context->s2c.length = SIV_GetKeyLength(context->algorithm);
+  UTI_GetRandomBytes(context->s2c.key, context->s2c.length);
+
+  *num_cookies = random() % max_cookies + 1;
+  for (i = 0; i < *num_cookies; i++) {
+    cookies[i].length = random() % (sizeof (cookies[i].cookie) + 1);
+    if (random() % 4 != 0)
+      cookies[i].length = cookies[i].length / 4 * 4;
+    memset(cookies[i].cookie, random(), cookies[i].length);
+  }
+
+  ntp_address->ip_addr.family = IPADDR_UNSPEC;
+  ntp_address->port = 0;
+
+  return 1;
+}
+
+static int
+get_request(NNC_Instance inst)
+{
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH], uniq_id[NTS_MIN_UNIQ_ID_LENGTH];
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  int expected_length, req_cookies;
+
+  memset(&packet, 0, sizeof (packet));
+  memset(&info, 0, sizeof (info));
+  info.version = 4;
+  info.mode = MODE_CLIENT;
+  info.length = random() % (sizeof (packet) + 1);
+  if (random() % 4 != 0)
+    info.length = info.length / 4 * 4;
+
+  if (inst->num_cookies > 0 && random() % 2) {
+    inst->num_cookies = 0;
+
+    TEST_CHECK(!NNC_GenerateRequestAuth(inst, &packet, &info));
+  }
+
+  while (!NNC_PrepareForAuth(inst)) {
+    inst->next_nke_attempt = SCH_GetLastEventMonoTime() + random() % 10 - 7;
+  }
+
+  TEST_CHECK(inst->num_cookies > 0);
+  TEST_CHECK(inst->siv);
+
+  memcpy(nonce, inst->nonce, sizeof (nonce));
+  memcpy(uniq_id, inst->uniq_id, sizeof (uniq_id));
+  TEST_CHECK(NNC_PrepareForAuth(inst));
+  TEST_CHECK(memcmp(nonce, inst->nonce, sizeof (nonce)) != 0);
+  TEST_CHECK(memcmp(uniq_id, inst->uniq_id, sizeof (uniq_id)) != 0);
+
+  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies + 1,
+                    MAX_TOTAL_COOKIE_LENGTH /
+                      (inst->cookies[inst->cookie_index].length + 4));
+  expected_length = info.length + 4 + sizeof (inst->uniq_id) +
+                    req_cookies * (4 + inst->cookies[inst->cookie_index].length) +
+                    4 + 4 + sizeof (inst->nonce) + SIV_GetTagLength(inst->siv);
+  DEBUG_LOG("length=%d cookie_length=%d expected_length=%d",
+            info.length, inst->cookies[inst->cookie_index].length, expected_length);
+
+  if (info.length % 4 == 0 && info.length >= NTP_HEADER_LENGTH &&
+      inst->cookies[inst->cookie_index].length % 4 == 0 &&
+      inst->cookies[inst->cookie_index].length >= (NTP_MIN_EF_LENGTH - 4) &&
+      expected_length <= sizeof (packet)) {
+    TEST_CHECK(NNC_GenerateRequestAuth(inst, &packet, &info));
+    TEST_CHECK(info.length == expected_length);
+    return 1;
+  } else {
+    TEST_CHECK(!NNC_GenerateRequestAuth(inst, &packet, &info));
+    return 0;
+  }
+}
+
+static void
+prepare_response(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info, int valid, int nak)
+{
+  unsigned char cookie[508], plaintext[528], nonce[448];
+  int nonce_length, ef_length, cookie_length, plaintext_length, min_auth_length;
+  int i, index, auth_start;
+  SIV_Instance siv;
+
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_SERVER);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_SERVER;
+  info->length = NTP_HEADER_LENGTH;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % (nak ? 2 : 8);
+
+  DEBUG_LOG("index=%d nak=%d", index, nak);
+
+  if (index != 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER, inst->uniq_id,
+                            sizeof (inst->uniq_id)));
+  if (index == 1)
+    ((unsigned char *)packet)[NTP_HEADER_LENGTH + 4]++;
+
+  if (nak) {
+    packet->stratum = NTP_INVALID_STRATUM;
+    packet->reference_id = htonl(NTP_KOD_NTS_NAK);
+    return;
+  }
+
+  nonce_length = random() % (sizeof (nonce)) + 1;
+
+  do {
+    cookie_length = random() % (sizeof (cookie) + 1);
+  } while (cookie_length % 4 != 0 ||
+           ((index != 2) == (cookie_length < NTP_MIN_EF_LENGTH - 4 ||
+                             cookie_length > NKE_MAX_COOKIE_LENGTH)));
+
+  min_auth_length = random() % (512 + 1);
+
+  DEBUG_LOG("nonce_length=%d cookie_length=%d min_auth_length=%d",
+            nonce_length, cookie_length, min_auth_length);
+
+  UTI_GetRandomBytes(nonce, nonce_length);
+  UTI_GetRandomBytes(cookie, cookie_length);
+
+  if (cookie_length >= 12 && cookie_length <= 32 && random() % 2 == 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE, cookie, cookie_length));
+
+  plaintext_length = 0;
+  if (index != 3) {
+    for (i = random() % ((sizeof (plaintext) - 16) / (cookie_length + 4)); i >= 0; i--) {
+      TEST_CHECK(NEF_SetField(plaintext, sizeof (plaintext), plaintext_length,
+                              NTP_EF_NTS_COOKIE, cookie,
+                              i == 0 ? cookie_length : random() % (cookie_length + 1) / 4 * 4,
+                              &ef_length));
+      plaintext_length += ef_length;
+    }
+  }
+  auth_start = info->length;
+  if (index != 4) {
+    if (index == 5) {
+      assert(plaintext_length + 16 <= sizeof (plaintext));
+      memset(plaintext + plaintext_length, 0, 16);
+      plaintext_length += 16;
+    }
+    siv = SIV_CreateInstance(inst->context.algorithm);
+    TEST_CHECK(siv);
+    TEST_CHECK(SIV_SetKey(siv, inst->context.s2c.key, inst->context.s2c.length));
+    TEST_CHECK(NNA_GenerateAuthEF(packet, info, siv,
+                                  nonce, nonce_length, plaintext, plaintext_length,
+                                  min_auth_length));
+    SIV_DestroyInstance(siv);
+  }
+  if (index == 6)
+    ((unsigned char *)packet)[auth_start + 8]++;
+  if (index == 7)
+    TEST_CHECK(NEF_AddField(packet, info, 0x7000, inst->uniq_id, sizeof (inst->uniq_id)));
+}
+
+void
+test_unit(void)
+{
+  NNC_Instance inst;
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  IPSockAddr addr;
+  IPAddr ip_addr;
+  int i, j, prev_num_cookies, valid;
+
+  TEST_CHECK(SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) > 0);
+
+  SCK_GetLoopbackIPAddress(AF_INET, &addr.ip_addr);
+  addr.port = 0;
+
+  inst = NNC_CreateInstance(&addr, "test", 0, 0);
+  TEST_CHECK(inst);
+
+  for (i = 0; i < 100000; i++) {
+    if (!get_request(inst))
+      continue;
+
+    valid = random() % 2;
+
+    TEST_CHECK(!inst->nak_response);
+    TEST_CHECK(!inst->ok_response);
+
+    if (random() % 2) {
+      prepare_response(inst, &packet, &info, 0, 1);
+      TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+      TEST_CHECK(!inst->nak_response);
+      TEST_CHECK(!inst->ok_response);
+      for (j = random() % 3; j > 0; j--) {
+        prepare_response(inst, &packet, &info, 1, 1);
+        TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+        TEST_CHECK(inst->nak_response);
+        TEST_CHECK(!inst->ok_response);
+      }
+    }
+
+    prev_num_cookies = inst->num_cookies;
+    prepare_response(inst, &packet, &info, valid, 0);
+
+    if (valid) {
+      TEST_CHECK(NNC_CheckResponseAuth(inst, &packet, &info));
+      TEST_CHECK(inst->num_cookies >= MIN(NTS_MAX_COOKIES, prev_num_cookies + 1));
+      TEST_CHECK(inst->ok_response);
+    }
+
+    prev_num_cookies = inst->num_cookies;
+    TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+    TEST_CHECK(inst->num_cookies == prev_num_cookies);
+    TEST_CHECK(inst->ok_response == valid);
+
+    if (random() % 10 == 0) {
+      TST_GetRandomAddress(&ip_addr, IPADDR_INET4, 32);
+      NNC_ChangeAddress(inst, &ip_addr);
+      TEST_CHECK(UTI_CompareIPs(&inst->nts_address.ip_addr, &ip_addr, NULL) == 0);
+    }
+  }
+
+  NNC_DestroyInstance(inst);
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_server.c b/test/unit/nts_ntp_server.c
new file mode 100644
index 0000000..40938d6
--- /dev/null
+++ b/test/unit/nts_ntp_server.c
@@ -0,0 +1,176 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <local.h>
+#include <sched.h>
+
+#include <nts_ntp_server.c>
+
+static void
+prepare_request(NTP_Packet *packet, NTP_PacketInfo *info, int valid, int nak)
+{
+  unsigned char uniq_id[NTS_MIN_UNIQ_ID_LENGTH], nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  SIV_Instance siv;
+  NKE_Context context;
+  NKE_Cookie cookie;
+  int i, index, cookie_start, auth_start;
+
+  context.algorithm = SERVER_SIV;
+  context.c2s.length = SIV_GetKeyLength(context.algorithm);
+  UTI_GetRandomBytes(&context.c2s.key, context.c2s.length);
+  context.s2c.length = SIV_GetKeyLength(context.algorithm);
+  UTI_GetRandomBytes(&context.s2c.key, context.s2c.length);
+
+  TEST_CHECK(NKS_GenerateCookie(&context, &cookie));
+
+  UTI_GetRandomBytes(uniq_id, sizeof (uniq_id));
+  UTI_GetRandomBytes(nonce, sizeof (nonce));
+
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_CLIENT);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_CLIENT;
+  info->length = NTP_HEADER_LENGTH;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 3;
+
+  DEBUG_LOG("valid=%d nak=%d index=%d", valid, nak, index);
+
+  if (index != 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER,
+                            uniq_id, sizeof (uniq_id)));
+
+  cookie_start = info->length;
+
+  if (index != 1)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE,
+                            cookie.cookie, cookie.length));
+
+  for (i = random() % 4; i > 0; i--)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
+                            cookie.cookie, cookie.length));
+
+  auth_start = info->length;
+
+  if (index != 2) {
+    siv = SIV_CreateInstance(context.algorithm);
+    TEST_CHECK(SIV_SetKey(siv, context.c2s.key, context.c2s.length));
+    TEST_CHECK(NNA_GenerateAuthEF(packet, info, siv, nonce, sizeof (nonce),
+                                  (const unsigned char *)"", 0, 0));
+    SIV_DestroyInstance(siv);
+  }
+
+  if (nak)
+    ((unsigned char *)packet)[(index == 2 ? cookie_start :
+                               (index == 1 ? auth_start :
+                                (random() % 2 ? cookie_start : auth_start))) +
+                              4 + random() % 16]++;
+}
+
+static void
+init_response(NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_SERVER);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_SERVER;
+  info->length = NTP_HEADER_LENGTH;
+}
+
+void
+test_unit(void)
+{
+  NTP_PacketInfo req_info, res_info;
+  NTP_Packet request, response;
+  int i, valid, nak;
+  uint32_t kod;
+
+  char conf[][100] = {
+    "ntsport 0",
+    "ntsprocesses 0",
+    "ntsserverkey nts_ke.key",
+    "ntsservercert nts_ke.crt",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  NKS_PreInitialise(0, 0, 0);
+  NKS_Initialise();
+  NNS_Initialise();
+
+  for (i = 0; i < 50000; i++) {
+    valid = random() % 2;
+    nak = random() % 2;
+    prepare_request(&request, &req_info, valid, nak);
+
+    TEST_CHECK(NNS_CheckRequestAuth(&request, &req_info, &kod) == (valid && !nak));
+
+    if (valid && !nak) {
+      TEST_CHECK(kod == 0);
+      TEST_CHECK(server->num_cookies > 0);
+
+      init_response(&response, &res_info);
+      TEST_CHECK(NNS_GenerateResponseAuth(&request, &req_info, &response, &res_info, kod));
+
+      TEST_CHECK(res_info.ext_fields == 2);
+      TEST_CHECK(server->num_cookies == 0);
+    } else if (valid && nak) {
+      TEST_CHECK(kod == NTP_KOD_NTS_NAK);
+      TEST_CHECK(server->num_cookies == 0);
+
+      init_response(&response, &res_info);
+      TEST_CHECK(NNS_GenerateResponseAuth(&request, &req_info, &response, &res_info, kod));
+
+      TEST_CHECK(res_info.ext_fields == 1);
+      TEST_CHECK(server->num_cookies == 0);
+    } else {
+      TEST_CHECK(kod == 0);
+      TEST_CHECK(server->num_cookies == 0);
+    }
+  }
+
+  NNS_Finalise();
+  NKS_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/quantiles.c b/test/unit/quantiles.c
new file mode 100644
index 0000000..5d97df6
--- /dev/null
+++ b/test/unit/quantiles.c
@@ -0,0 +1,68 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+ */
+
+#include <local.h>
+#include "test.h"
+
+#include <quantiles.c>
+
+void
+test_unit(void)
+{
+  int i, j, k, min_k, max_k, q, r, in_order, out_order;
+  QNT_Instance inst;
+  double x;
+
+  in_order = out_order = 0;
+
+  for (i = 0; i < 100; i++) {
+    r = random() % 10 + 1;
+    q = random() % 20 + 2;
+    do {
+      min_k = random() % (q - 1) + 1;
+      max_k = random() % (q - 1) + 1;
+    } while (min_k > max_k);
+
+    inst = QNT_CreateInstance(min_k, max_k, q, r, 1e-9);
+
+    TEST_CHECK(min_k == QNT_GetMinK(inst));
+
+    for (j = 0; j < 3000; j++) {
+      x = TST_GetRandomDouble(0.0, 2e-6);
+      QNT_Accumulate(inst, x);
+      for (k = min_k; k < max_k; k++)
+        if (j < max_k - min_k) {
+          TEST_CHECK(QNT_GetQuantile(inst, k) <= QNT_GetQuantile(inst, k + 1));
+        } else if (j > 1000) {
+          if (QNT_GetQuantile(inst, k) <= QNT_GetQuantile(inst, k + 1))
+            in_order++;
+          else
+            out_order++;
+        }
+    }
+
+    QNT_Reset(inst);
+    TEST_CHECK(inst->n_set == 0);
+
+    QNT_DestroyInstance(inst);
+  }
+
+  TEST_CHECK(in_order > 100 * out_order);
+}
diff --git a/test/unit/regress.c b/test/unit/regress.c
new file mode 100644
index 0000000..f47d1c4
--- /dev/null
+++ b/test/unit/regress.c
@@ -0,0 +1,119 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+#include <regress.c>
+#include "test.h"
+
+#define POINTS 64
+
+void
+test_unit(void)
+{
+  double x[POINTS], x2[POINTS], y[POINTS], w[POINTS];
+  double b0, b1, b2, s2, sb0, sb1, slope, slope2, intercept, sd, median;
+  double xrange, yrange, wrange, x2range;
+  int i, j, n, m, c1, c2, c3, runs, best_start, dof;
+
+  for (n = 3; n <= POINTS; n++) {
+    for (i = 0; i < 200; i++) {
+      slope = TST_GetRandomDouble(-0.1, 0.1);
+      intercept = TST_GetRandomDouble(-1.0, 1.0);
+      sd = TST_GetRandomDouble(1e-6, 1e-4);
+      slope2 = (random() % 2 ? 1 : -1) * TST_GetRandomDouble(0.1, 0.5);
+
+      DEBUG_LOG("iteration %d n=%d intercept=%e slope=%e sd=%e",
+                i, n, intercept, slope, sd);
+
+      for (j = 0; j < n; j++) {
+        x[j] = -j;
+        y[j] = intercept + slope * x[j] + (j % 2 ? 1 : -1) * TST_GetRandomDouble(1e-6, sd);
+        w[j] = TST_GetRandomDouble(1.0, 2.0);
+        x2[j] = (y[j] - intercept - slope * x[j]) / slope2;
+      }
+
+      RGR_WeightedRegression(x, y, w, n, &b0, &b1, &s2, &sb0, &sb1);
+      DEBUG_LOG("WR b0=%e b1=%e s2=%e sb0=%e sb1=%e", b0, b1, s2, sb0, sb1);
+      TEST_CHECK(fabs(b0 - intercept) < sd + 1e-3);
+      TEST_CHECK(fabs(b1 - slope) < sd);
+
+      if (RGR_FindBestRegression(x, y, w, n, 0, 3, &b0, &b1, &s2, &sb0, &sb1,
+                                 &best_start, &runs, &dof)) {
+        DEBUG_LOG("BR b0=%e b1=%e s2=%e sb0=%e sb1=%e runs=%d bs=%d dof=%d",
+                  b0, b1, s2, sb0, sb1, runs, best_start, dof);
+
+        TEST_CHECK(fabs(b0 - intercept) < sd + 1e-3);
+        TEST_CHECK(fabs(b1 - slope) < sd);
+      }
+
+      if (RGR_MultipleRegress(x, x2, y, n, &b2)) {
+        DEBUG_LOG("MR b2=%e", b2);
+        TEST_CHECK(fabs(b2 - slope2) < 1e-6);
+      }
+
+      for (j = 0; j < n / 7; j++)
+        y[random() % n] += 100 * sd;
+
+      if (RGR_FindBestRobustRegression(x, y, n, 1e-8, &b0, &b1, &runs, &best_start)) {
+        DEBUG_LOG("BRR b0=%e b1=%e runs=%d bs=%d", b0, b1, runs, best_start);
+
+        TEST_CHECK(fabs(b0 - intercept) < sd + 1e-2);
+        TEST_CHECK(fabs(b1 - slope) < 5.0 * sd);
+      }
+
+      for (j = 0; j < n; j++)
+        x[j] = random() % 4 * TST_GetRandomDouble(-1000, 1000);
+
+      median = RGR_FindMedian(x, n);
+
+      for (j = c1 = c2 = c3 = 0; j < n; j++) {
+        if (x[j] < median)
+          c1++;
+        if (x[j] > median)
+          c3++;
+        else
+          c2++;
+      }
+
+      TEST_CHECK(c1 + c2 >= c3 && c1 <= c2 + c3);
+
+      xrange = TST_GetRandomDouble(1e-6, pow(10.0, random() % 10));
+      yrange = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      wrange = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      x2range = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      m = random() % n;
+
+      for (j = 0; j < n; j++) {
+        x[j] = (j ? x[j - 1] : 0.0) + TST_GetRandomDouble(1e-6, xrange);
+        y[j] = TST_GetRandomDouble(-yrange, yrange);
+        w[j] = 1.0 + TST_GetRandomDouble(0.0, wrange);
+        x2[j] = TST_GetRandomDouble(-x2range, x2range);
+      }
+
+      RGR_WeightedRegression(x, y, w, n, &b0, &b1, &s2, &sb0, &sb1);
+
+      if (RGR_FindBestRegression(x + m, y + m, w, n - m, m, 3, &b0, &b1, &s2, &sb0, &sb1,
+                                 &best_start, &runs, &dof))
+        ;
+      if (RGR_MultipleRegress(x, x2, y, n, &b2))
+        ;
+      if (RGR_FindBestRobustRegression(x, y, n, 1e-8, &b0, &b1, &runs, &best_start))
+        ;
+    }
+  }
+}
diff --git a/test/unit/samplefilt.c b/test/unit/samplefilt.c
new file mode 100644
index 0000000..19d2f70
--- /dev/null
+++ b/test/unit/samplefilt.c
@@ -0,0 +1,120 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <local.h>
+#include "test.h"
+
+#define LCL_GetSysPrecisionAsQuantum() (1.0e-6)
+
+#include <samplefilt.c>
+
+void
+test_unit(void)
+{
+  NTP_Sample sample_in, sample_out;
+  SPF_Instance filter;
+  int i, j, k, sum_count, min_samples, max_samples;
+  double mean, combine_ratio, sum_err;
+
+  LCL_Initialise();
+
+  memset(&sample_in, 0, sizeof (sample_in));
+  memset(&sample_out, 0, sizeof (sample_out));
+
+  for (i = 0; i <= 100; i++) {
+    max_samples = random() % 20 + 1;
+    min_samples = random() % (max_samples) + 1;
+    combine_ratio = TST_GetRandomDouble(0.0, 1.0);
+
+    filter = SPF_CreateInstance(min_samples, max_samples, 2.0, combine_ratio);
+
+    TEST_CHECK(max_samples == SPF_GetMaxSamples(filter));
+
+    for (j = 0, sum_count = 0, sum_err = 0.0; j < 100; j++) {
+      DEBUG_LOG("iteration %d/%d", i, j);
+
+      mean = TST_GetRandomDouble(-1.0e3, 1.0e3);
+      UTI_ZeroTimespec(&sample_in.time);
+
+      for (k = 0; k < 100; k++) {
+        UTI_AddDoubleToTimespec(&sample_in.time, TST_GetRandomDouble(1.0e-1, 1.0e2),
+                                &sample_in.time);
+        sample_in.offset = mean + TST_GetRandomDouble(-1.0, 1.0);
+        sample_in.peer_dispersion = TST_GetRandomDouble(1.0e-4, 2.0e-4);
+        sample_in.root_dispersion = TST_GetRandomDouble(1.0e-3, 2.0e-3);
+        sample_in.peer_delay = TST_GetRandomDouble(1.0e-2, 2.0e-2);
+        sample_in.root_delay = TST_GetRandomDouble(1.0e-1, 2.0e-1);
+
+        TEST_CHECK(SPF_AccumulateSample(filter, &sample_in));
+        TEST_CHECK(!SPF_AccumulateSample(filter, &sample_in));
+
+        TEST_CHECK(SPF_GetNumberOfSamples(filter) == MIN(k + 1, max_samples));
+
+        SPF_GetLastSample(filter, &sample_out);
+        TEST_CHECK(!memcmp(&sample_in, &sample_out, sizeof (sample_in)));
+
+        SPF_SlewSamples(filter, &sample_in.time, 0.0, 0.0);
+        SPF_CorrectOffset(filter, 0.0);
+        SPF_AddDispersion(filter, 0.0);
+
+        if (k + 1 < min_samples)
+          TEST_CHECK(!SPF_GetFilteredSample(filter, &sample_out));
+
+        TEST_CHECK(SPF_GetNumberOfSamples(filter) == MIN(k + 1, max_samples));
+      }
+
+      if (random() % 10) {
+        TEST_CHECK(SPF_GetFilteredSample(filter, &sample_out));
+
+        TEST_CHECK(SPF_GetAvgSampleDispersion(filter) <= 2.0);
+
+        sum_err += sample_out.offset - mean;
+        sum_count++;
+
+        TEST_CHECK(UTI_CompareTimespecs(&sample_out.time, &sample_in.time) <= 0 &&
+                   sample_out.time.tv_sec >= 0);
+        TEST_CHECK(fabs(sample_out.offset - mean) <= 1.0);
+        TEST_CHECK(sample_out.peer_dispersion >= 1.0e-4 &&
+                   (sample_out.peer_dispersion <= 2.0e-4 || filter->max_samples > 1));
+        TEST_CHECK(sample_out.root_dispersion >= 1.0e-3 &&
+                   (sample_out.root_dispersion <= 2.0e-3 || filter->max_samples > 1));
+        TEST_CHECK(sample_out.peer_delay >= 1.0e-2 &&
+                   sample_out.peer_delay <= 2.0e-2);
+        TEST_CHECK(sample_out.root_delay >= 1.0e-1 &&
+                   sample_out.root_delay <= 2.0e-1);
+
+        if (max_samples == 1)
+          TEST_CHECK(!memcmp(&sample_in, &sample_out, sizeof (sample_in)));
+
+      } else {
+        SPF_DropSamples(filter);
+        TEST_CHECK(filter->last < 0);
+      }
+
+      TEST_CHECK(SPF_GetNumberOfSamples(filter) == 0);
+    }
+
+    TEST_CHECK(fabs(sum_err / sum_count) < 0.3);
+
+    SPF_DestroyInstance(filter);
+  }
+
+  LCL_Finalise();
+}
diff --git a/test/unit/siv.c b/test/unit/siv.c
new file mode 100644
index 0000000..76846c8
--- /dev/null
+++ b/test/unit/siv.c
@@ -0,0 +1,321 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <logging.h>
+#include <siv.h>
+#include "test.h"
+
+#ifdef HAVE_SIV
+
+struct siv_test {
+  SIV_Algorithm algorithm;
+  const unsigned char key[64];
+  int key_length;
+  const unsigned char nonce[128];
+  int nonce_length;
+  const unsigned char assoc[128];
+  int assoc_length;
+  const unsigned char plaintext[128];
+  int plaintext_length;
+  const unsigned char ciphertext[128];
+  int ciphertext_length;
+};
+
+void
+test_unit(void)
+{
+  struct siv_test tests[] = {
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "", 0,
+      "", 0,
+      "\x22\x3e\xb5\x94\xe0\xe0\x25\x4b\x00\x25\x8e\x21\x9a\x1c\xa4\x21", 16
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "", 0,
+      "\xd7\x20\x19\x89\xc6\xdb\xc6\xd6\x61\xfc\x62\xbc\x86\x5e\xee\xef", 16
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "", 0,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "\xb6\xc1\x60\xe9\xc2\xfd\x2a\xe8\xde\xc5\x36\x8b\x2a\x33\xed\xe1"
+      "\x14\xff\xb3\x97\x34\x5c\xcb\xe4\x4a\xa4\xde\xac\xd9\x36\x90\x46", 32
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e", 15,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c", 15,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4", 15,
+      "\x03\x8c\x41\x51\xba\x7a\x8f\x77\x6e\x56\x31\x99\x42\x0b\xc7\x03"
+      "\xe7\x6c\x67\xc9\xda\xb7\x0d\x5b\x44\x06\x26\x5a\xd0\xd2\x3b", 31
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7", 16,
+      "\x5c\x05\x23\x65\xf4\x57\x0a\xa0\xfb\x38\x3e\xce\x9b\x75\x85\xeb"
+      "\x68\x85\x19\x36\x0c\x7c\x48\x11\x40\xcb\x9b\x57\x9a\x0e\x65\x32", 32
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
+      "\xd5", 17,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b"
+      "\xa0", 17,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7"
+      "\x08", 17,
+      "\xaf\x58\x4b\xe7\x82\x1e\x96\x19\x29\x91\x25\xe0\xdd\x80\x3b\x49"
+      "\xa5\x11\xcd\xb6\x08\xf3\x76\xa0\xb6\xfa\x15\x82\xf3\x95\xe1\xeb"
+      "\xbd", 33
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\xb0\x5a\x1b\xc7\x56\xe7\xb6\x2c\xb4\x85\xe5\x56\xa5\x28\xc0\x6c"
+      "\x2f\x3b\x0b\x9d\x1a\x0c\xdf\x69\x47\xe0\xcc\xc0\x87\xaa\x5c\x09"
+      "\x98\x48\x8d\x6a\x8e\x1e\x05\xd7\x8b\x68\x74\x83\xb5\x1d\xf1\x2c", 48,
+      "\xe5\x8b\xd2\x6a\x30\xc5\xc5\x61\xcc\xbd\x7c\x27\xbf\xfe\xf9\x06"
+      "\x00\x5b\xd7\xfc\x11\x0b\xcf\x16\x61\xef\xac\x05\xa7\xaf\xec\x27"
+      "\x41\xc8\x5e\x9e\x0d\xf9\x2f\xaf\x20\x79\x17\xe5\x17\x91\x2a\x27"
+      "\x34\x1c\xbc\xaf\xeb\xef\x7f\x52\xe7\x1e\x4c\x2a\xca\xbd\x2b\xbe"
+      "\x34\xd6\xfb\x69\xd3\x3e\x49\x59\x60\xb4\x26\xc9\xb8\xce\xba", 79,
+      "\x6c\xe7\xcf\x7e\xab\x7b\xa0\xe1\xa7\x22\xcb\x88\xde\x5e\x42\xd2"
+      "\xec\x79\xe0\xa2\xcf\x5f\x0f\x6f\x6b\x89\x57\xcd\xae\x17\xd4\xc2"
+      "\xf3\x1b\xa2\xa8\x13\x78\x23\x2f\x83\xa8\xd4\x0c\xc0\xd2\xf3\x99"
+      "\xae\x81\xa1\xca\x5b\x5f\x45\xa6\x6f\x0c\x8a\xf3\xd4\x67\x40\x81"
+      "\x26\xe2\x01\x86\xe8\x5a\xd5\xf8\x58\x80\x9f\x56\xaa\x76\x96\xbf"
+      "\x31", 81,
+      "\x9a\x06\x33\xe0\xee\x00\x6a\x9b\xc8\x20\xd5\xe2\xc2\xed\xb5\x75"
+      "\xfa\x9e\x42\x2a\x31\x6b\xda\xca\xaa\x7d\x31\x8b\x84\x7a\xb8\xd7"
+      "\x8a\x81\x25\x64\xed\x41\x9b\xa9\x77\x10\xbd\x05\x0c\x4e\xc5\x31"
+      "\x0c\xa2\x86\xec\x8a\x94\xc8\x24\x23\x3c\x13\xee\xa5\x51\xc9\xdf"
+      "\x48\xc9\x55\xc5\x2f\x40\x73\x3f\x98\xbb\x8d\x69\x78\x46\x64\x17"
+      "\x8d\x49\x2f\x14\x62\xa4\x7c\x2a\x57\x38\x87\xce\xc6\x72\xd3\x5c"
+      "\xa1", 97
+    },
+    { 0, "", 0 }
+  };
+
+  unsigned char plaintext[sizeof (((struct siv_test *)NULL)->plaintext)];
+  unsigned char ciphertext[sizeof (((struct siv_test *)NULL)->ciphertext)];
+  SIV_Instance siv;
+  int i, j, r;
+
+  TEST_CHECK(SIV_CreateInstance(0) == NULL);
+
+  for (i = 0; tests[i].algorithm != 0; i++) {
+    DEBUG_LOG("testing %d (%d)", (int)tests[i].algorithm, i);
+
+    assert(tests[i].key_length <= sizeof (tests[i].key));
+    assert(tests[i].nonce_length <= sizeof (tests[i].nonce));
+    assert(tests[i].assoc_length <= sizeof (tests[i].assoc));
+    assert(tests[i].plaintext_length <= sizeof (tests[i].plaintext));
+    assert(tests[i].ciphertext_length <= sizeof (tests[i].ciphertext));
+
+    siv = SIV_CreateInstance(tests[i].algorithm);
+    TEST_CHECK(siv != NULL);
+
+    TEST_CHECK(SIV_GetKeyLength(tests[i].algorithm) == tests[i].key_length);
+
+    r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].plaintext, tests[i].plaintext_length,
+                    ciphertext, tests[i].ciphertext_length);
+    TEST_CHECK(!r);
+    r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].ciphertext, tests[i].ciphertext_length,
+                    plaintext, tests[i].plaintext_length);
+    TEST_CHECK(!r);
+
+    for (j = -1; j < 1024; j++) {
+      r = SIV_SetKey(siv, tests[i].key, j);
+      TEST_CHECK(r == (j == tests[i].key_length));
+    }
+
+    TEST_CHECK(SIV_GetTagLength(siv) == tests[i].ciphertext_length - tests[i].plaintext_length);
+
+    r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].plaintext, tests[i].plaintext_length,
+                    ciphertext, tests[i].ciphertext_length);
+    TEST_CHECK(r);
+
+#if 0
+    for (j = 0; j < tests[i].ciphertext_length; j++) {
+      printf("\\x%02x", ciphertext[j]);
+      if (j % 16 == 15)
+        printf("\n");
+    }
+    printf("\n");
+#endif
+    TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) == 0);
+
+    for (j = -1; j < tests[i].nonce_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, j,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, tests[i].ciphertext_length);
+      if (j > 0) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < tests[i].assoc_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, j,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, tests[i].ciphertext_length);
+      if (j >= 0) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < tests[i].plaintext_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, j,
+                      ciphertext, j + SIV_GetTagLength(siv));
+      if (j >= 0) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, j + SIV_GetTagLength(siv)) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < 2 * tests[i].plaintext_length; j++) {
+      if (j == tests[i].plaintext_length)
+        continue;
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, j,
+                      ciphertext, tests[i].ciphertext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < 2 * tests[i].ciphertext_length; j++) {
+      if (j == tests[i].ciphertext_length)
+        continue;
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, j);
+      TEST_CHECK(!r);
+    }
+
+    r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].ciphertext, tests[i].ciphertext_length,
+                    plaintext, tests[i].plaintext_length);
+    TEST_CHECK(r);
+    TEST_CHECK(memcmp(plaintext, tests[i].plaintext, tests[i].plaintext_length) == 0);
+
+    for (j = -1; j < tests[i].nonce_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, j,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < tests[i].assoc_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, j,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < 2 * tests[i].ciphertext_length; j++) {
+      if (j == tests[i].ciphertext_length)
+        continue;
+
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, j,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < tests[i].plaintext_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, j);
+      TEST_CHECK(!r);
+
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, j + SIV_GetTagLength(siv),
+                      plaintext, j);
+      TEST_CHECK(!r);
+    }
+
+    SIV_DestroyInstance(siv);
+  }
+
+  siv = SIV_CreateInstance(tests[0].algorithm);
+  for (i = 0; i < 1000; i++) {
+    for (j = 0; tests[j].algorithm == tests[0].algorithm; j++) {
+      r = SIV_SetKey(siv, tests[j].key, tests[j].key_length);
+      TEST_CHECK(r);
+      r = SIV_Encrypt(siv, tests[j].nonce, tests[j].nonce_length,
+                      tests[j].assoc, tests[j].assoc_length,
+                      tests[j].plaintext, tests[j].plaintext_length,
+                      ciphertext, tests[j].ciphertext_length);
+      TEST_CHECK(r);
+      r = SIV_Decrypt(siv, tests[j].nonce, tests[j].nonce_length,
+                      tests[j].assoc, tests[j].assoc_length,
+                      tests[j].ciphertext, tests[j].ciphertext_length,
+                      plaintext, tests[j].plaintext_length);
+      TEST_CHECK(r);
+    }
+  }
+  SIV_DestroyInstance(siv);
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/smooth.c b/test/unit/smooth.c
new file mode 100644
index 0000000..998a4d1
--- /dev/null
+++ b/test/unit/smooth.c
@@ -0,0 +1,63 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <smooth.c>
+#include "test.h"
+
+void
+test_unit(void)
+{
+  int i, j;
+  struct timespec ts;
+  double offset, freq, wander;
+  char conf[] = "smoothtime 300 0.01";
+
+  CNF_Initialise(0, 0);
+  CNF_ParseLine(NULL, 1, conf);
+
+  LCL_Initialise();
+  SMT_Initialise();
+  locked = 0;
+
+  for (i = 0; i < 500; i++) {
+    UTI_ZeroTimespec(&ts);
+    SMT_Reset(&ts);
+
+    DEBUG_LOG("iteration %d", i);
+
+    offset = (random() % 1000000 - 500000) / 1.0e6;
+    freq = (random() % 1000000 - 500000) / 1.0e9;
+    update_smoothing(&ts, offset, freq);
+
+    for (j = 0; j < 10000; j++) {
+      update_smoothing(&ts, 0.0, 0.0);
+      UTI_AddDoubleToTimespec(&ts, 16.0, &ts);
+      get_smoothing(&ts, &offset, &freq, &wander);
+    }
+
+    TEST_CHECK(fabs(offset) < 1e-12);
+    TEST_CHECK(fabs(freq) < 1e-12);
+    TEST_CHECK(fabs(wander) < 1e-12);
+  }
+
+  SMT_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
diff --git a/test/unit/sources.c b/test/unit/sources.c
new file mode 100644
index 0000000..155e819
--- /dev/null
+++ b/test/unit/sources.c
@@ -0,0 +1,289 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <sources.c>
+#include "test.h"
+
+static SRC_Instance
+create_source(SRC_Type type, IPAddr *addr, int authenticated, int sel_options)
+{
+  TST_GetRandomAddress(addr, IPADDR_UNSPEC, -1);
+
+  return SRC_CreateNewInstance(UTI_IPToRefid(addr), type, authenticated, sel_options,
+                               type == SRC_NTP ? addr : NULL,
+                               SRC_DEFAULT_MINSAMPLES, SRC_DEFAULT_MAXSAMPLES, 0.0, 1.0);
+}
+
+void
+test_unit(void)
+{
+  SRC_AuthSelectMode sel_mode;
+  SRC_Instance srcs[16];
+  IPAddr addrs[16];
+  RPT_SourceReport report;
+  NTP_Sample sample;
+  int i, j, k, l, n1, n2, n3, n4, samples, sel_options;
+  char conf[128];
+
+  CNF_Initialise(0, 0);
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  REF_Initialise();
+  NSR_Initialise();
+
+  REF_SetMode(REF_ModeIgnore);
+
+  for (i = 0; i < 1000; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      TEST_CHECK(n_sources == j);
+
+      sel_options = i & random() & (SRC_SELECT_NOSELECT | SRC_SELECT_PREFER |
+                                    SRC_SELECT_TRUST | SRC_SELECT_REQUIRE);
+
+      DEBUG_LOG("added source %d options %d", j, sel_options);
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, sel_options);
+      SRC_UpdateReachability(srcs[j], 1);
+
+      samples = (i + j) % 5 + 3;
+
+      sample.offset = TST_GetRandomDouble(-1.0, 1.0);
+
+      for (k = 0; k < samples; k++) {
+        SCH_GetLastEventTime(&sample.time, NULL, NULL);
+        UTI_AddDoubleToTimespec(&sample.time, TST_GetRandomDouble(k - samples, k - samples + 1),
+                                &sample.time);
+
+        sample.offset += TST_GetRandomDouble(-1.0e-2, 1.0e-2);
+        sample.peer_delay = TST_GetRandomDouble(1.0e-6, 1.0e-1);
+        sample.peer_dispersion = TST_GetRandomDouble(1.0e-6, 1.0e-1);
+        sample.root_delay = sample.peer_delay;
+        sample.root_dispersion = sample.peer_dispersion;
+
+        if (random() % 2)
+          SRC_UpdateStatus(srcs[j], 1, random() % 4);
+
+        DEBUG_LOG("source %d sample %d offset %f delay %f disp %f", j, k,
+                  sample.offset, sample.peer_delay, sample.peer_dispersion);
+
+        SRC_AccumulateSample(srcs[j], &sample);
+      }
+
+      for (k = 0; k <= j; k++) {
+        int passed = 0, trusted = 0, trusted_passed = 0, required = 0, required_passed = 0;
+        double trusted_lo = DBL_MAX, trusted_hi = DBL_MIN;
+        double passed_lo = DBL_MAX, passed_hi = DBL_MIN;
+
+        SRC_SelectSource(srcs[k]);
+        DEBUG_LOG("source %d status %c", k, get_status_char(sources[k]->status));
+
+        for (l = 0; l <= j; l++) {
+          TEST_CHECK(sources[l]->status > SRC_OK && sources[l]->status <= SRC_SELECTED);
+          if (sources[l]->sel_options & SRC_SELECT_NOSELECT) {
+            TEST_CHECK(sources[l]->status == SRC_UNSELECTABLE);
+          } else if (sources[l]->leap == LEAP_Unsynchronised) {
+            TEST_CHECK(sources[l]->status == SRC_UNSYNCHRONISED);
+          } else if (sources[l]->status != SRC_BAD_DISTANCE) {
+            if (sources[l]->status >= SRC_NONPREFERRED) {
+              passed++;
+              if (passed_lo > sources[l]->sel_info.lo_limit)
+                passed_lo = sources[l]->sel_info.lo_limit;
+              if (passed_hi < sources[l]->sel_info.hi_limit)
+                passed_hi = sources[l]->sel_info.hi_limit;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_TRUST) {
+              trusted++;
+              if (trusted_lo > sources[l]->sel_info.lo_limit)
+                trusted_lo = sources[l]->sel_info.lo_limit;
+              if (trusted_hi < sources[l]->sel_info.hi_limit)
+                trusted_hi = sources[l]->sel_info.hi_limit;
+              if (sources[l]->status >= SRC_NONPREFERRED)
+                trusted_passed++;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_REQUIRE) {
+              required++;
+              if (sources[l]->status >= SRC_NONPREFERRED)
+                required_passed++;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_PREFER)
+              TEST_CHECK(sources[l]->status != SRC_NONPREFERRED);
+          }
+        }
+
+        DEBUG_LOG("sources %d passed %d trusted %d/%d required %d/%d", j + 1, passed,
+                  trusted_passed, trusted, required_passed, required);
+
+        TEST_CHECK(!trusted || !passed || (passed_lo >= trusted_lo && passed_hi <= trusted_hi));
+        TEST_CHECK(!passed || !trusted || trusted_passed >= 1);
+        TEST_CHECK(!passed || !required || required_passed > 0);
+
+        for (l = 0; l <= j; l++) {
+          TEST_CHECK(sources[l]->leap_vote ==
+                     (sources[l]->status >= SRC_NONPREFERRED &&
+                      (!trusted || sources[l]->sel_options & SRC_SELECT_TRUST)));
+        }
+      }
+    }
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      SRC_ReportSource(j, &report, &sample.time);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  for (i = 0; i < 16; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      TEST_CHECK(n_sources == j);
+
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, 0);
+      SRC_UpdateReachability(srcs[j], 1);
+
+      samples = 8;
+      for (k = 0; k < samples; k++) {
+        SCH_GetLastEventTime(&sample.time, NULL, NULL);
+        UTI_AddDoubleToTimespec(&sample.time, k - samples, &sample.time);
+        if (j != 0)
+          UTI_AddDoubleToTimespec(&sample.time, -i * (1.0e-3 / LCL_GetMaxClockError()), &sample.time);
+
+        sample.offset = (k % 2) * 1e-8;
+        sample.peer_delay = sample.root_delay = 2.0e-3 * (j + 1);
+        sample.peer_dispersion = sample.root_dispersion = 4.0e-3;
+
+        SRC_AccumulateSample(srcs[j], &sample);
+        SRC_UpdateStatus(srcs[j], 1, LEAP_Normal);
+      }
+    }
+
+    SRC_SelectSource(srcs[0]);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      DEBUG_LOG("%d %c %f", j, get_status_char(srcs[j]->status),
+                srcs[j]->sel_info.root_distance);
+      if (j == 0)
+        TEST_CHECK(sources[j]->status == SRC_SELECTED);
+      else if (j < 11 - i)
+        TEST_CHECK(sources[j]->status == SRC_UNSELECTED);
+      else
+        TEST_CHECK(sources[j]->status == SRC_DISTANT);
+    }
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      SCH_GetLastEventTime(&sample.time, NULL, NULL);
+      SRC_ReportSource(j, &report, &sample.time);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  TEST_CHECK(CNF_GetAuthSelectMode() == SRC_AUTHSELECT_MIX);
+
+  for (i = 0; i < 1000; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    switch (i % 4) {
+      case 0:
+        snprintf(conf, sizeof (conf), "authselectmode require");
+        sel_mode = SRC_AUTHSELECT_REQUIRE;
+        break;
+      case 1:
+        snprintf(conf, sizeof (conf), "authselectmode prefer");
+        sel_mode = SRC_AUTHSELECT_PREFER;
+        break;
+      case 2:
+        snprintf(conf, sizeof (conf), "authselectmode mix");
+        sel_mode = SRC_AUTHSELECT_MIX;
+        break;
+      case 3:
+        snprintf(conf, sizeof (conf), "authselectmode ignore");
+        sel_mode = SRC_AUTHSELECT_IGNORE;
+        break;
+    }
+
+    CNF_ParseLine(NULL, 0, conf);
+    TEST_CHECK(CNF_GetAuthSelectMode() == sel_mode);
+
+    sel_options = random() & (SRC_SELECT_PREFER | SRC_SELECT_TRUST | SRC_SELECT_REQUIRE);
+
+    n1 = random() % 3;
+    n2 = random() % 3;
+    n3 = random() % 3;
+    n4 = random() % 3;
+    assert(n1 + n2 + n3 < sizeof (srcs) / sizeof (srcs[0]));
+
+    for (j = 0; j < n1; j++)
+      srcs[j] = create_source(SRC_REFCLOCK, &addrs[j], random() % 2, sel_options);
+    for (; j < n1 + n2; j++)
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 1, sel_options);
+    for (; j < n1 + n2 + n3; j++)
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, sel_options);
+    for (; j < n1 + n2 + n3 + n4; j++)
+      srcs[j] = create_source(random() % 2 ? SRC_REFCLOCK : SRC_NTP, &addrs[j],
+                              random() % 2, sel_options | SRC_SELECT_NOSELECT);
+
+    switch (sel_mode) {
+      case SRC_AUTHSELECT_IGNORE:
+        for (j = 0; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        break;
+      case SRC_AUTHSELECT_MIX:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options ==
+                     (sel_options | (n2 > 0 && n3 > 0 ? SRC_SELECT_REQUIRE | SRC_SELECT_TRUST : 0)));
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        break;
+      case SRC_AUTHSELECT_PREFER:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == (sel_options | (n2 > 0 ? SRC_SELECT_NOSELECT : 0)));
+        break;
+      case SRC_AUTHSELECT_REQUIRE:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == (sel_options | SRC_SELECT_NOSELECT));
+        break;
+      default:
+        assert(0);
+    }
+
+    for (j = n1 + n2 + n3; j < n1 + n2 + n3 + n4; j++)
+      TEST_CHECK(srcs[j]->sel_options == (sel_options | SRC_SELECT_NOSELECT));
+
+    for (j = n1 + n2 + n3 + n4 - 1; j >= 0; j--) {
+      if (j < n1 + n2)
+        TEST_CHECK(srcs[j]->sel_options == sel_options);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  NSR_Finalise();
+  REF_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
diff --git a/test/unit/test.c b/test/unit/test.c
new file mode 100644
index 0000000..94619c1
--- /dev/null
+++ b/test/unit/test.c
@@ -0,0 +1,181 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <logging.h>
+#include <localp.h>
+#include <util.h>
+
+#include "test.h"
+
+void
+TST_Fail(int line)
+{
+  printf("FAIL (on line %d)\n", line);
+  exit(1);
+}
+
+void
+TST_Skip(int line)
+{
+  printf("SKIP (on line %d)\n", line);
+  exit(0);
+}
+
+int
+main(int argc, char **argv)
+{
+  LOG_Severity log_severity;
+  char *test_name, *s;
+  int i, seed = 0;
+  struct timeval tv;
+
+  test_name = argv[0];
+  s = strrchr(test_name, '.');
+  if (s)
+    *s = '\0';
+  s = strrchr(test_name, '/');
+  if (s)
+    test_name = s + 1;
+
+  log_severity = LOGS_FATAL;
+
+  for (i = 1; i < argc; i++) {
+    if (!strcmp(argv[i], "-d")) {
+      log_severity = LOGS_DEBUG;
+    } else if (!strcmp(argv[i], "-s") && i + 1 < argc) {
+      seed = atoi(argv[++i]);
+    } else {
+      fprintf(stderr, "Unknown option\n");
+      exit(1);
+    }
+  }
+
+  gettimeofday(&tv, NULL);
+  srandom(seed ? seed : tv.tv_sec ^ (tv.tv_usec << 10));
+
+  printf("Testing %-30s ", test_name);
+  fflush(stdout);
+
+  LOG_Initialise();
+  LOG_SetMinSeverity(log_severity);
+
+  test_unit();
+
+  LOG_Finalise();
+
+  printf("PASS\n");
+
+  return 0;
+}
+
+double
+TST_GetRandomDouble(double min, double max)
+{
+  return min + random() / 2147483647.0 * (max - min);
+}
+
+void
+TST_GetRandomAddress(IPAddr *ip, int family, int bits)
+{
+  if (family != IPADDR_INET4 && family != IPADDR_INET6)
+    family = random() % 2 ? IPADDR_INET4 : IPADDR_INET6;
+
+  ip->family = family;
+
+  if (family == IPADDR_INET4) {
+    if (bits < 0)
+      bits = 32;
+    assert(bits <= 32);
+
+    if (bits > 16)
+      ip->addr.in4 = (uint32_t)random() % (1U << (bits - 16)) << 16 |
+                     (uint32_t)random() % (1U << 16);
+    else
+      ip->addr.in4 = (uint32_t)random() % (1U << bits);
+  } else {
+    int i, b;
+
+    if (bits < 0)
+      bits = 128;
+    assert(bits <= 128);
+
+    for (i = 0, b = 120; i < 16; i++, b -= 8) {
+      if (b >= bits) {
+        ip->addr.in6[i] = 0;
+      } else {
+        ip->addr.in6[i] = random() % (1U << MIN(bits - b, 8));
+      }
+    }
+  }
+}
+
+void
+TST_SwapAddressBit(IPAddr *ip, unsigned int b)
+{
+  if (ip->family == IPADDR_INET4) {
+    assert(b < 32);
+    ip->addr.in4 ^= 1U << (31 - b);
+  } else if (ip->family == IPADDR_INET6) {
+    assert(b < 128);
+    ip->addr.in6[b / 8] ^= 1U << (7 - b % 8);
+  } else {
+    assert(0);
+  }
+}
+
+static double
+read_frequency(void)
+{
+  return 0.0;
+}
+
+static double
+set_frequency(double freq_ppm)
+{
+  return 0.0;
+}
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+}
+
+static int
+apply_step_offset(double offset)
+{
+  return 0;
+}
+
+static void
+offset_convert(struct timespec *raw, double *corr, double *err)
+{
+  *corr = 0.0;
+  if (err)
+    *err = 0.0;
+}
+
+void
+TST_RegisterDummyDrivers(void)
+{
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency, accrue_offset,
+                            apply_step_offset, offset_convert, NULL, NULL);
+}
diff --git a/test/unit/test.h b/test/unit/test.h
new file mode 100644
index 0000000..00d261d
--- /dev/null
+++ b/test/unit/test.h
@@ -0,0 +1,52 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#ifndef GOT_TEST_H
+#define GOT_TEST_H
+
+#include <addressing.h>
+
+extern void test_unit(void);
+
+#define TEST_CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      TST_Fail(__LINE__); \
+      exit(1); \
+    } \
+  } while (0)
+
+#define TEST_REQUIRE(expr) \
+  do { \
+    if (!(expr)) { \
+      TST_Skip(__LINE__); \
+      exit(0); \
+    } \
+  } while (0)
+
+extern void TST_Fail(int line);
+extern void TST_Skip(int line);
+
+extern double TST_GetRandomDouble(double min, double max);
+extern void TST_GetRandomAddress(IPAddr *ip, int family, int bits);
+extern void TST_SwapAddressBit(IPAddr *ip, unsigned int b);
+extern void TST_RegisterDummyDrivers(void);
+
+#endif
diff --git a/test/unit/util.c b/test/unit/util.c
new file mode 100644
index 0000000..112676d
--- /dev/null
+++ b/test/unit/util.c
@@ -0,0 +1,744 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017-2018, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <util.c>
+#include "test.h"
+
+static volatile int handled_signal = 0;
+
+static void
+handle_signal(int signal)
+{
+  handled_signal = signal;
+}
+
+void
+test_unit(void)
+{
+  struct timespec ts, ts2, ts3, ts4;
+  char buf[16], *s, *s2, *words[3];
+  NTP_int64 ntp_ts, ntp_ts2, ntp_fuzz;
+  NTP_int32 ntp32_ts;
+  struct timeval tv;
+  double x, y, nan, inf;
+  IPAddr ip, ip2, ip3;
+  IPSockAddr ip_saddr;
+  Timespec tspec;
+  Float f;
+  int i, j, c;
+  uid_t uid;
+  gid_t gid;
+  struct stat st;
+  FILE *file;
+
+  for (i = -31; i < 31; i++) {
+    x = pow(2.0, i);
+    y = UTI_Log2ToDouble(i);
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+  }
+
+  for (i = -89; i < 63; i++) {
+    x = pow(2.0, i);
+    y = UTI_FloatNetworkToHost(UTI_FloatHostToNetwork(x));
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+  }
+
+  for (i = 0; i < 100000; i++) {
+    x = TST_GetRandomDouble(-1000.0, 1000.0);
+    y = UTI_FloatNetworkToHost(UTI_FloatHostToNetwork(x));
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+
+    UTI_GetRandomBytes(&f, sizeof (f));
+    x = UTI_FloatNetworkToHost(f);
+    TEST_CHECK(x > 0.0 || x <= 0.0);
+  }
+
+  TEST_CHECK(UTI_DoubleToNtp32(1.0) == htonl(65536));
+  TEST_CHECK(UTI_DoubleToNtp32(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(1.0 / (65536.0)) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32(1.000001 / (65536.0)) == htonl(2));
+  TEST_CHECK(UTI_DoubleToNtp32(1.000001) == htonl(65537));
+  TEST_CHECK(UTI_DoubleToNtp32(1000000) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32(-1.0) == htonl(0));
+
+  UTI_DoubleToTimeval(0.4e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 0);
+  UTI_DoubleToTimeval(-0.4e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 0);
+  UTI_DoubleToTimeval(0.5e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 1);
+  UTI_DoubleToTimeval(-0.5e-6, &tv);
+  TEST_CHECK(tv.tv_sec == -1);
+  TEST_CHECK(tv.tv_usec == 999999);
+
+  UTI_DoubleToTimespec(0.9e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  UTI_DoubleToTimespec(1.0e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 1);
+  UTI_DoubleToTimespec(-0.9e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  UTI_DoubleToTimespec(-1.0e-9, &ts);
+  TEST_CHECK(ts.tv_sec == -1);
+  TEST_CHECK(ts.tv_nsec == 999999999);
+
+  ntp_ts.hi = htonl(JAN_1970);
+  ntp_ts.lo = 0xffffffff;
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+#if defined(HAVE_LONG_TIME_T) && NTP_ERA_SPLIT > 0
+  TEST_CHECK(ts.tv_sec == 0x100000000LL * (1 + (NTP_ERA_SPLIT - 1) / 0x100000000LL));
+#else
+  TEST_CHECK(ts.tv_sec == 0);
+#endif
+  TEST_CHECK(ts.tv_nsec == 999999999);
+
+  ntp_ts.hi = htonl(JAN_1970 - 1);
+  ntp_ts.lo = htonl(0xffffffff);
+  ntp_ts2.hi = htonl(JAN_1970 + 1);
+  ntp_ts2.lo = htonl(0x80000000);
+  TEST_CHECK(fabs(UTI_DiffNtp64ToDouble(&ntp_ts, &ntp_ts2) + 1.5) < 1e-9);
+  TEST_CHECK(fabs(UTI_DiffNtp64ToDouble(&ntp_ts2, &ntp_ts) - 1.5) < 1e-9);
+
+  UTI_AddDoubleToTimespec(&ts, 1e-9, &ts);
+#if defined(HAVE_LONG_TIME_T) && NTP_ERA_SPLIT > 0
+  TEST_CHECK(ts.tv_sec == 1 + 0x100000000LL * (1 + (NTP_ERA_SPLIT - 1) / 0x100000000LL));
+#else
+  TEST_CHECK(ts.tv_sec == 1);
+#endif
+  TEST_CHECK(ts.tv_nsec == 0);
+
+  ntp_fuzz.hi = 0;
+  ntp_fuzz.lo = htonl(0xff1234ff);
+
+  UTI_TimespecToNtp64(&ts, &ntp_ts, &ntp_fuzz);
+  TEST_CHECK(ntp_ts.hi == htonl(JAN_1970 + 1));
+  TEST_CHECK(ntp_ts.lo == ntp_fuzz.lo);
+
+  ts.tv_sec = ts.tv_nsec = 1;
+  UTI_ZeroTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  TEST_CHECK(UTI_IsZeroTimespec(&ts));
+
+  ntp_ts.hi = ntp_ts.lo == 1;
+  UTI_ZeroNtp64(&ntp_ts);
+  TEST_CHECK(ntp_ts.hi == 0);
+  TEST_CHECK(ntp_ts.lo == 0);
+
+  tv.tv_sec = tv.tv_usec = 1;
+  UTI_TimevalToTimespec(&tv, &ts);
+  TEST_CHECK(ts.tv_sec == 1);
+  TEST_CHECK(ts.tv_nsec == 1000);
+
+  UTI_TimespecToTimeval(&ts, &tv);
+  TEST_CHECK(tv.tv_sec == 1);
+  TEST_CHECK(tv.tv_usec == 1);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 500000000;
+  TEST_CHECK(fabs(UTI_TimespecToDouble(&ts) - 1.5) < 1.0e-15);
+
+  UTI_DoubleToTimespec(2.75, &ts);
+  TEST_CHECK(ts.tv_sec == 2);
+  TEST_CHECK(ts.tv_nsec == 750000000);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 1200000000;
+  UTI_NormaliseTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 2);
+  TEST_CHECK(ts.tv_nsec == 200000000);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = -200000000;
+  UTI_NormaliseTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 800000000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = 500000;
+  TEST_CHECK(fabs(UTI_TimevalToDouble(&tv) - 1.5) < 1.0e-15);
+
+  UTI_DoubleToTimeval(2.75, &tv);
+  TEST_CHECK(tv.tv_sec == 2);
+  TEST_CHECK(tv.tv_usec == 750000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = 1200000;
+  UTI_NormaliseTimeval(&tv);
+  TEST_CHECK(tv.tv_sec == 2);
+  TEST_CHECK(tv.tv_usec == 200000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = -200000;
+  UTI_NormaliseTimeval(&tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 800000);
+
+  UTI_ZeroTimespec(&ts);
+  UTI_TimespecToNtp64(&ts, &ntp_ts, &ntp_fuzz);
+  TEST_CHECK(ntp_ts.hi == 0);
+  TEST_CHECK(ntp_ts.lo == 0);
+
+  TEST_CHECK(UTI_IsZeroNtp64(&ntp_ts));
+
+  ts.tv_sec = 1;
+  ntp_ts.hi = htonl(1);
+
+  TEST_CHECK(!UTI_IsZeroTimespec(&ts));
+  TEST_CHECK(!UTI_IsZeroNtp64(&ntp_ts));
+
+  ts.tv_sec = 0;
+  ntp_ts.hi = 0;
+  ts.tv_nsec = 1;
+  ntp_ts.lo = htonl(1);
+
+  TEST_CHECK(!UTI_IsZeroTimespec(&ts));
+  TEST_CHECK(!UTI_IsZeroNtp64(&ntp_ts));
+
+  ntp_ts.hi = 0;
+  ntp_ts.lo = 0;
+
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+  TEST_CHECK(UTI_IsZeroTimespec(&ts));
+  UTI_TimespecToNtp64(&ts, &ntp_ts, NULL);
+  TEST_CHECK(UTI_IsZeroNtp64(&ntp_ts));
+
+  ntp_fuzz.hi = htonl(1);
+  ntp_fuzz.lo = htonl(3);
+  ntp_ts.hi = htonl(1);
+  ntp_ts.lo = htonl(2);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  ntp_ts.hi = htonl(0x80000002);
+  ntp_ts.lo = htonl(2);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  ntp_fuzz.hi = htonl(0x90000001);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, &ntp_ts, NULL, NULL));
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, NULL, &ntp_ts, NULL));
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, NULL, NULL, &ntp_ts));
+  TEST_CHECK(!UTI_IsEqualAnyNtp64(&ntp_ts, &ntp_fuzz, &ntp_fuzz, &ntp_fuzz));
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 2;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 3;
+
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts) == 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) < 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts2, &ts) > 0);
+
+  ts2.tv_sec = 2;
+
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts) == 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) < 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts2, &ts) > 0);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  UTI_DiffTimespecs(&ts3, &ts, &ts2);
+  TEST_CHECK(ts3.tv_sec == 0);
+  TEST_CHECK(ts3.tv_nsec == 500000000);
+  TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - 0.5) < 1.0e-15);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  ts2.tv_sec = 3;
+  ts2.tv_nsec = 750000000;
+  UTI_DiffTimespecs(&ts3, &ts, &ts2);
+  TEST_CHECK(ts3.tv_sec == -2);
+  TEST_CHECK(ts3.tv_nsec == 500000000);
+  TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - -1.5) < 1.0e-15);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  UTI_AddDoubleToTimespec(&ts, 2.5, &ts2);
+  TEST_CHECK(ts2.tv_sec == 4);
+  TEST_CHECK(ts2.tv_nsec == 750000000);
+
+  ts.tv_sec = 4;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  UTI_AverageDiffTimespecs(&ts, &ts2, &ts3, &x);
+  TEST_CHECK(ts3.tv_sec == 3);
+  TEST_CHECK(ts3.tv_nsec == 125000000);
+  TEST_CHECK(x == -2.75);
+
+  ts.tv_sec = 4;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  ts3.tv_sec = 5;
+  ts3.tv_nsec = 250000000;
+  UTI_AddDiffToTimespec(&ts, &ts2, &ts3, &ts4);
+  TEST_CHECK(ts4.tv_sec == 8);
+  TEST_CHECK(ts4.tv_nsec == 0);
+
+  ts.tv_sec = 1600000000;
+  ts.tv_nsec = 123;
+  s = UTI_TimespecToString(&ts);
+  TEST_CHECK(strcmp(s, "1600000000.000000123") == 0);
+
+  ntp_ts.hi = 1;
+  ntp_ts.hi = 2;
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+  s = UTI_Ntp64ToString(&ntp_ts);
+  s2 = UTI_TimespecToString(&ts);
+  TEST_CHECK(strcmp(s, s2) == 0);
+
+  s = UTI_RefidToString(0x41424344);
+  TEST_CHECK(strcmp(s, "ABCD") == 0);
+
+  ip.family = IPADDR_UNSPEC;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "[UNSPEC]") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_INET4;
+  ip.addr.in4 = 0x7f010203;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "127.1.2.3") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0x7f010203);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_INET6;
+  memset(&ip.addr.in6, 0, sizeof (ip.addr.in6));
+  ip.addr.in6[0] = 0xab;
+  ip.addr.in6[15] = 0xcd;
+  s = UTI_IPToString(&ip);
+#ifdef FEAT_IPV6
+  TEST_CHECK(strcmp(s, "ab00::cd") == 0);
+#else
+  TEST_CHECK(strcmp(s, "ab00:0000:0000:0000:0000:0000:0000:00cd") == 0);
+#endif
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0x5f9aa602);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_ID;
+  ip.addr.id = 12345;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "ID#0000012345") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_UNSPEC + 10;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "[UNKNOWN]") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  TEST_CHECK(UTI_StringToIP("200.4.5.6", &ip));
+  TEST_CHECK(ip.family == IPADDR_INET4);
+  TEST_CHECK(ip.addr.in4 == 0xc8040506);
+
+#ifdef FEAT_IPV6
+  TEST_CHECK(UTI_StringToIP("1234::7890", &ip));
+  TEST_CHECK(ip.family == IPADDR_INET6);
+  TEST_CHECK(ip.addr.in6[0] == 0x12 && ip.addr.in6[1] == 0x34);
+  TEST_CHECK(ip.addr.in6[2] == 0x00 && ip.addr.in6[13] == 0x00);
+  TEST_CHECK(ip.addr.in6[14] == 0x78 && ip.addr.in6[15] == 0x90);
+#else
+  TEST_CHECK(!UTI_StringToIP("1234::7890", &ip));
+#endif
+
+  TEST_CHECK(!UTI_StringToIP("ID#0000012345", &ip));
+
+  TEST_CHECK(UTI_IsStringIP("1.2.3.4"));
+  TEST_CHECK(!UTI_IsStringIP("127.3.3"));
+  TEST_CHECK(!UTI_IsStringIP("127.3"));
+  TEST_CHECK(!UTI_IsStringIP("127"));
+#ifdef FEAT_IPV6
+  TEST_CHECK(UTI_IsStringIP("1234:5678::aaaa"));
+#else
+  TEST_CHECK(!UTI_IsStringIP("1234:5678::aaaa"));
+#endif
+  TEST_CHECK(!UTI_StringToIP("ID#0000012345", &ip));
+
+  TEST_CHECK(!UTI_StringToIdIP("1.2.3.4", &ip));
+  TEST_CHECK(UTI_StringToIdIP("ID#0000056789", &ip));
+  TEST_CHECK(ip.family == IPADDR_ID);
+  TEST_CHECK(ip.addr.id == 56789);
+
+  for (i = IPADDR_UNSPEC; i <= IPADDR_ID + 1; i++) {
+    ip.family = i;
+    TEST_CHECK(UTI_IsIPReal(&ip) == (i == IPADDR_INET4 || i == IPADDR_INET6));
+  }
+
+  ip.family = IPADDR_UNSPEC;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_UNSPEC));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_UNSPEC);
+
+  ip.family = IPADDR_INET4;
+  ip.addr.in4 = 0x12345678;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_INET4));
+  TEST_CHECK(ip2.addr.in4 == htonl(0x12345678));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_INET4);
+  TEST_CHECK(ip3.addr.in4 == 0x12345678);
+
+  ip.family = IPADDR_INET6;
+  for (i = 0; i < 16; i++)
+    ip.addr.in6[i] = i;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_INET6));
+  for (i = 0; i < 16; i++)
+    TEST_CHECK(ip.addr.in6[i] == i);
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_INET6);
+  for (i = 0; i < 16; i++)
+    TEST_CHECK(ip.addr.in6[i] == i);
+
+  ip.family = IPADDR_ID;
+  ip.addr.in4 = 0x87654321;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_ID));
+  TEST_CHECK(ip2.addr.in4 == htonl(0x87654321));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_ID);
+  TEST_CHECK(ip3.addr.in4 == 0x87654321);
+
+  for (i = 0; i < 16; i++)
+    ip.addr.in6[i] = 0x80;
+  ip2 = ip;
+
+  for (i = IPADDR_UNSPEC; i <= IPADDR_ID; i++) {
+    ip.family = i;
+    ip2.family = i + 1;
+    TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) < 0);
+    TEST_CHECK(UTI_CompareIPs(&ip2, &ip, NULL) > 0);
+    ip2 = ip;
+    ip2.addr.in4++;
+    if (i == IPADDR_UNSPEC) {
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) == 0);
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) == 0);
+    } else {
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) < 0);
+      TEST_CHECK(UTI_CompareIPs(&ip2, &ip, NULL) > 0);
+      if (i == IPADDR_ID) {
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) < 0);
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip2) < 0);
+      } else {
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) == 0);
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip2) < 0);
+      }
+    }
+  }
+
+  ip_saddr.ip_addr.family = IPADDR_INET4;
+  ip_saddr.ip_addr.addr.in4 = 0x01020304;
+  ip_saddr.port = 12345;
+  s = UTI_IPSockAddrToString(&ip_saddr);
+  TEST_CHECK(strcmp(s, "1.2.3.4:12345") == 0);
+
+  s = UTI_TimeToLogForm(2000000000);
+  TEST_CHECK(strcmp(s, "2033-05-18 03:33:20") == 0);
+
+  ts.tv_sec = 3;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 4;
+  ts2.tv_nsec = 250000000;
+  UTI_AdjustTimespec(&ts, &ts2, &ts3, &x, 2.0, -5.0);
+  TEST_CHECK(fabs(x - 6.5) < 1.0e-15);
+  TEST_CHECK((ts3.tv_sec == 10 && ts3.tv_nsec == 0) ||
+             (ts3.tv_sec == 9 && ts3.tv_nsec == 999999999));
+
+  for (i = -32; i <= 32; i++) {
+    for (j = c = 0; j < 1000; j++) {
+      UTI_GetNtp64Fuzz(&ntp_fuzz, i);
+      if (i <= 0)
+        TEST_CHECK(ntp_fuzz.hi == 0);
+      if (i < 0)
+        TEST_CHECK(ntohl(ntp_fuzz.lo) < 1U << (32 + i));
+      else if (i < 32)
+        TEST_CHECK(ntohl(ntp_fuzz.hi) < 1U << i);
+      if (ntohl(ntp_fuzz.lo) >= 1U << (31 + CLAMP(-31, i, 0)))
+        c++;
+    }
+
+    if (i == -32)
+      TEST_CHECK(c == 0);
+    else
+      TEST_CHECK(c > 400 && c < 600);
+  }
+
+  TEST_CHECK(UTI_DoubleToNtp32(-1.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(1e-9) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32(32768.0) == htonl(0x80000000));
+  TEST_CHECK(UTI_DoubleToNtp32(65536.0) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32(65537.0) == htonl(0xffffffff));
+
+  TEST_CHECK(UTI_DoubleToNtp32f28(-1.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32f28(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32f28(1e-9) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32f28(4e-9) == htonl(2));
+  TEST_CHECK(UTI_DoubleToNtp32f28(8.0) == htonl(0x80000000));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.0) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.1) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.1) == htonl(0xffffffff));
+
+  TEST_CHECK(UTI_Ntp32f28ToDouble(htonl(0xffffffff)) >= 65535.999);
+  for (i = 0; i < 100000; i++) {
+    UTI_GetRandomBytes(&ntp32_ts, sizeof (ntp32_ts));
+    TEST_CHECK(UTI_DoubleToNtp32(UTI_Ntp32ToDouble(ntp32_ts)) == ntp32_ts);
+    TEST_CHECK(UTI_DoubleToNtp32f28(UTI_Ntp32f28ToDouble(ntp32_ts)) == ntp32_ts);
+  }
+
+  ts.tv_nsec = 0;
+
+  ts.tv_sec = 10;
+  TEST_CHECK(!UTI_IsTimeOffsetSane(&ts, -20.0));
+
+#ifdef HAVE_LONG_TIME_T
+  ts.tv_sec = NTP_ERA_SPLIT + (1LL << 32);
+#else
+  ts.tv_sec = 0x7fffffff - MIN_ENDOFTIME_DISTANCE;
+#endif
+  TEST_CHECK(!UTI_IsTimeOffsetSane(&ts, 10.0));
+  TEST_CHECK(UTI_IsTimeOffsetSane(&ts, -20.0));
+
+  TEST_CHECK(UTI_Log2ToDouble(-1) == 0.5);
+  TEST_CHECK(UTI_Log2ToDouble(0) == 1.0);
+  TEST_CHECK(UTI_Log2ToDouble(1) == 2.0);
+  TEST_CHECK(UTI_Log2ToDouble(-31) < UTI_Log2ToDouble(-30));
+  TEST_CHECK(UTI_Log2ToDouble(-32) == UTI_Log2ToDouble(-31));
+  TEST_CHECK(UTI_Log2ToDouble(30) < UTI_Log2ToDouble(32));
+  TEST_CHECK(UTI_Log2ToDouble(31) == UTI_Log2ToDouble(32));
+
+  UTI_TimespecHostToNetwork(&ts, &tspec);
+#ifdef HAVE_LONG_TIME_T
+  TEST_CHECK(tspec.tv_sec_high == htonl(ts.tv_sec >> 32));
+#else
+  TEST_CHECK(tspec.tv_sec_high == htonl(TV_NOHIGHSEC));
+#endif
+  TEST_CHECK(tspec.tv_sec_low == htonl(ts.tv_sec));
+  TEST_CHECK(tspec.tv_nsec == htonl(ts.tv_nsec));
+  UTI_TimespecNetworkToHost(&tspec, &ts2);
+  TEST_CHECK(!UTI_CompareTimespecs(&ts, &ts2));
+
+  TEST_CHECK(UTI_CmacNameToAlgorithm("AES128") == CMC_AES128);
+  TEST_CHECK(UTI_CmacNameToAlgorithm("AES256") == CMC_AES256);
+  TEST_CHECK(UTI_CmacNameToAlgorithm("NOSUCHCMAC") == CMC_INVALID);
+
+  TEST_CHECK(UTI_HashNameToAlgorithm("MD5") == HSH_MD5);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA1") == HSH_SHA1);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA256") == HSH_SHA256);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA384") == HSH_SHA384);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA512") == HSH_SHA512);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-224") == HSH_SHA3_224);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-256") == HSH_SHA3_256);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-384") == HSH_SHA3_384);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-512") == HSH_SHA3_512);
+  TEST_CHECK(UTI_HashNameToAlgorithm("TIGER") == HSH_TIGER);
+  TEST_CHECK(UTI_HashNameToAlgorithm("WHIRLPOOL") == HSH_WHIRLPOOL);
+  TEST_CHECK(UTI_HashNameToAlgorithm("NOSUCHHASH") == HSH_INVALID);
+
+  i = open("/dev/null", 0);
+  TEST_CHECK(UTI_FdSetCloexec(i));
+  j = fcntl(i, F_GETFD);
+  TEST_CHECK(j & F_GETFD);
+  close(i);
+
+  UTI_SetQuitSignalsHandler(handle_signal, 0);
+  TEST_CHECK(handled_signal == 0);
+  kill(getpid(), SIGPIPE);
+  while (handled_signal == 0)
+    ;
+  TEST_CHECK(handled_signal == SIGPIPE);
+
+  s = UTI_PathToDir("/aaa/bbb/ccc/ddd");
+  TEST_CHECK(!strcmp(s, "/aaa/bbb/ccc"));
+  Free(s);
+  s = UTI_PathToDir("aaa");
+  TEST_CHECK(!strcmp(s, "."));
+  Free(s);
+  s = UTI_PathToDir("/aaaa");
+  TEST_CHECK(!strcmp(s, "/"));
+  Free(s);
+
+  nan = strtod("nan", NULL);
+  inf = strtod("inf", NULL);
+
+  TEST_CHECK(MIN(2.0, -1.0) == -1.0);
+  TEST_CHECK(MIN(-1.0, 2.0) == -1.0);
+  TEST_CHECK(MIN(inf, 2.0) == 2.0);
+
+  TEST_CHECK(MAX(2.0, -1.0) == 2.0);
+  TEST_CHECK(MAX(-1.0, 2.0) == 2.0);
+  TEST_CHECK(MAX(inf, 2.0) == inf);
+
+  TEST_CHECK(CLAMP(1.0, -1.0, 2.0) == 1.0);
+  TEST_CHECK(CLAMP(1.0, 3.0, 2.0) == 2.0);
+  TEST_CHECK(CLAMP(1.0, inf, 2.0) == 2.0);
+  TEST_CHECK(CLAMP(1.0, nan, 2.0) == 2.0);
+
+  TEST_CHECK(SQUARE(3.0) == 3.0 * 3.0);
+
+  rmdir("testdir");
+
+  uid = geteuid();
+  gid = getegid();
+
+  TEST_CHECK(UTI_CreateDirAndParents("testdir", 0700, uid, gid));
+
+  TEST_CHECK(UTI_CheckDirPermissions("testdir", 0700, uid, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0300, uid, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0700, uid + 1, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0700, uid, gid + 1));
+
+  umask(0);
+
+  unlink("testfile");
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'r', 0);
+  TEST_CHECK(!file);
+  TEST_CHECK(stat("testfile", &st) < 0);
+
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'w', 0644);
+  TEST_CHECK(file);
+  TEST_CHECK(stat("testfile", &st) == 0);
+  TEST_CHECK((st.st_mode & 0777) == 0644);
+  fclose(file);
+
+  file = UTI_OpenFile(".", "test", "file", 'W', 0640);
+  TEST_CHECK(file);
+  TEST_CHECK(stat("testfile", &st) == 0);
+  TEST_CHECK((st.st_mode & 0777) == 0640);
+  fclose(file);
+
+  file = UTI_OpenFile(NULL, "test", "file", 'r', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RenameTempFile(NULL, "testfil", "e", NULL));
+  TEST_CHECK(stat("testfil", &st) == 0);
+  file = UTI_OpenFile(NULL, "testfil", NULL, 'R', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RenameTempFile(NULL, "test", "fil", "file"));
+  TEST_CHECK(stat("testfile", &st) == 0);
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'R', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RemoveFile(NULL, "testfile", NULL));
+  TEST_CHECK(stat("testfile", &st) < 0);
+  TEST_CHECK(!UTI_RemoveFile(NULL, "testfile", NULL));
+
+  for (i = c = 0; i < 100000; i++) {
+    j = random() % (sizeof (buf) + 1);
+    UTI_GetRandomBytesUrandom(buf, j);
+    if (j && buf[j - 1] % 2)
+      c++;
+    if (random() % 10000 == 0) {
+      UTI_ResetGetRandomFunctions();
+      TEST_CHECK(!urandom_file);
+    }
+  }
+  TEST_CHECK(c > 46000 && c < 48000);
+
+  for (i = c = 0; i < 100000; i++) {
+    j = random() % (sizeof (buf) + 1);
+    UTI_GetRandomBytes(buf, j);
+    if (j && buf[j - 1] % 2)
+      c++;
+    if (random() % 10000 == 0) {
+      UTI_ResetGetRandomFunctions();
+#if HAVE_GETRANDOM
+      TEST_CHECK(getrandom_buf_available == 0);
+#endif
+    }
+  }
+  TEST_CHECK(c > 46000 && c < 48000);
+
+  assert(sizeof (buf) >= 16);
+  TEST_CHECK(UTI_HexToBytes("", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("0", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, 8) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, sizeof (buf)) == 9);
+  TEST_CHECK(memcmp(buf, "\x00\x12\x34\x56\x78\x9A\xBC\xDE\xF0", 9) == 0);
+  memcpy(buf, "AB123456780001", 15);
+  TEST_CHECK(UTI_HexToBytes(buf, buf, sizeof (buf)) == 7);
+  TEST_CHECK(memcmp(buf, "\xAB\x12\x34\x56\x78\x00\x01", 7) == 0);
+
+  TEST_CHECK(UTI_BytesToHex("", 0, buf, 0) == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 14) == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 15) == 1);
+  TEST_CHECK(strcmp(buf, "AB123456780001") == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 0, buf, 15) == 1);
+  TEST_CHECK(strcmp(buf, "") == 0);
+
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 0);
+  TEST_CHECK(!words[0]);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "     ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 0);
+  TEST_CHECK(!words[0]);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a  \n ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 0);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "  a  ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 2);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", " \n  a") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 4);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a   b") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 1) == 2);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a   b") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 2) == 2);
+  TEST_CHECK(words[0] == buf + 0);
+  TEST_CHECK(words[1] == buf + 4);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(strcmp(words[1], "b") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", " a b ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 2);
+  TEST_CHECK(words[0] == buf + 1);
+  TEST_CHECK(words[1] == buf + 3);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(strcmp(words[1], "b") == 0);
+}
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..c4c8934
--- /dev/null
+++ b/util.c
@@ -0,0 +1,1550 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009, 2012-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Various utility functions
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+#include "hash.h"
+
+#define NSEC_PER_SEC 1000000000
+
+/* ================================================== */
+
+void
+UTI_ZeroTimespec(struct timespec *ts)
+{
+  ts->tv_sec = 0;
+  ts->tv_nsec = 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsZeroTimespec(struct timespec *ts)
+{
+  return !ts->tv_sec && !ts->tv_nsec;
+}
+
+/* ================================================== */
+
+void
+UTI_TimevalToTimespec(const struct timeval *tv, struct timespec *ts)
+{
+  ts->tv_sec = tv->tv_sec;
+  ts->tv_nsec = 1000 * tv->tv_usec;
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecToTimeval(const struct timespec *ts, struct timeval *tv)
+{
+  tv->tv_sec = ts->tv_sec;
+  tv->tv_usec = ts->tv_nsec / 1000;
+}
+
+/* ================================================== */
+
+double
+UTI_TimespecToDouble(const struct timespec *ts)
+{
+  return ts->tv_sec + 1.0e-9 * ts->tv_nsec;
+}
+
+/* ================================================== */
+
+void
+UTI_DoubleToTimespec(double d, struct timespec *ts)
+{
+  ts->tv_sec = d;
+  ts->tv_nsec = 1.0e9 * (d - ts->tv_sec);
+  UTI_NormaliseTimespec(ts);
+}
+
+/* ================================================== */
+
+void
+UTI_NormaliseTimespec(struct timespec *ts)
+{
+  if (ts->tv_nsec >= NSEC_PER_SEC || ts->tv_nsec < 0) {
+    ts->tv_sec += ts->tv_nsec / NSEC_PER_SEC;
+    ts->tv_nsec = ts->tv_nsec % NSEC_PER_SEC;
+
+    /* If seconds are negative nanoseconds would end up negative too */
+    if (ts->tv_nsec < 0) {
+      ts->tv_sec--;
+      ts->tv_nsec += NSEC_PER_SEC;
+    }
+  }
+}
+
+/* ================================================== */
+
+double
+UTI_TimevalToDouble(const struct timeval *tv)
+{
+  return tv->tv_sec + 1.0e-6 * tv->tv_usec;
+}
+
+/* ================================================== */
+
+void
+UTI_DoubleToTimeval(double a, struct timeval *b)
+{
+  double frac_part;
+
+  b->tv_sec = a;
+  frac_part = 1.0e6 * (a - b->tv_sec);
+  b->tv_usec = round(frac_part);
+  UTI_NormaliseTimeval(b);
+}
+
+/* ================================================== */
+
+void
+UTI_NormaliseTimeval(struct timeval *x)
+{
+  /* Reduce tv_usec to within +-1000000 of zero. JGH */
+  if ((x->tv_usec >= 1000000) || (x->tv_usec <= -1000000)) {
+    x->tv_sec += x->tv_usec/1000000;
+    x->tv_usec = x->tv_usec%1000000;
+  }
+
+  /* Make tv_usec positive. JGH */
+   if (x->tv_usec < 0) {
+    --x->tv_sec;
+    x->tv_usec += 1000000;
+ }
+
+}
+
+/* ================================================== */
+
+int
+UTI_CompareTimespecs(const struct timespec *a, const struct timespec *b)
+{
+  if (a->tv_sec < b->tv_sec)
+    return -1;
+  if (a->tv_sec > b->tv_sec)
+    return 1;
+  if (a->tv_nsec < b->tv_nsec)
+    return -1;
+  if (a->tv_nsec > b->tv_nsec)
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+void
+UTI_DiffTimespecs(struct timespec *result, const struct timespec *a, const struct timespec *b)
+{
+  result->tv_sec = a->tv_sec - b->tv_sec;
+  result->tv_nsec = a->tv_nsec - b->tv_nsec;
+  UTI_NormaliseTimespec(result);
+}
+
+/* ================================================== */
+
+/* Calculate result = a - b and return as a double */
+double
+UTI_DiffTimespecsToDouble(const struct timespec *a, const struct timespec *b)
+{
+  return ((double)a->tv_sec - (double)b->tv_sec) + 1.0e-9 * (a->tv_nsec - b->tv_nsec);
+}
+
+/* ================================================== */
+
+void
+UTI_AddDoubleToTimespec(const struct timespec *start, double increment, struct timespec *end)
+{
+  time_t int_part;
+
+  int_part = increment;
+  end->tv_sec = start->tv_sec + int_part;
+  end->tv_nsec = start->tv_nsec + 1.0e9 * (increment - int_part);
+  UTI_NormaliseTimespec(end);
+}
+
+/* ================================================== */
+
+/* Calculate the average and difference (as a double) of two timespecs */
+void
+UTI_AverageDiffTimespecs(const struct timespec *earlier, const struct timespec *later,
+                         struct timespec *average, double *diff)
+{
+  *diff = UTI_DiffTimespecsToDouble(later, earlier);
+  UTI_AddDoubleToTimespec(earlier, *diff / 2.0, average);
+}
+
+/* ================================================== */
+
+void
+UTI_AddDiffToTimespec(const struct timespec *a, const struct timespec *b,
+                      const struct timespec *c, struct timespec *result)
+{
+  double diff;
+
+  diff = UTI_DiffTimespecsToDouble(a, b);
+  UTI_AddDoubleToTimespec(c, diff, result);
+}
+
+/* ================================================== */
+
+#define POOL_ENTRIES 16
+#define BUFFER_LENGTH 64
+static char buffer_pool[POOL_ENTRIES][BUFFER_LENGTH];
+static int  pool_ptr = 0;
+
+#define NEXT_BUFFER (buffer_pool[pool_ptr = ((pool_ptr + 1) % POOL_ENTRIES)])
+
+/* ================================================== */
+/* Convert a timespec into a temporary string, largely for diagnostic display */
+
+char *
+UTI_TimespecToString(const struct timespec *ts)
+{
+  char *result;
+
+  result = NEXT_BUFFER;
+#ifdef HAVE_LONG_TIME_T
+  snprintf(result, BUFFER_LENGTH, "%"PRId64".%09lu",
+           (int64_t)ts->tv_sec, (unsigned long)ts->tv_nsec);
+#else
+  snprintf(result, BUFFER_LENGTH, "%ld.%09lu",
+           (long)ts->tv_sec, (unsigned long)ts->tv_nsec);
+#endif
+  return result;
+}
+
+/* ================================================== */
+/* Convert an NTP timestamp into a temporary string, largely
+   for diagnostic display */
+
+char *
+UTI_Ntp64ToString(const NTP_int64 *ntp_ts)
+{
+  struct timespec ts;
+  UTI_Ntp64ToTimespec(ntp_ts, &ts);
+  return UTI_TimespecToString(&ts);
+}
+
+/* ================================================== */
+
+char *
+UTI_RefidToString(uint32_t ref_id)
+{
+  unsigned int i, j, c;
+  char *result;
+
+  result = NEXT_BUFFER;
+
+  for (i = j = 0; i < 4 && i < BUFFER_LENGTH - 1; i++) {
+    c = (ref_id >> (24 - i * 8)) & 0xff;
+    if (isprint(c))
+      result[j++] = c;
+  }
+
+  result[j] = '\0';
+
+  return result;
+}
+
+/* ================================================== */
+
+char *
+UTI_IPToString(const IPAddr *addr)
+{
+  unsigned long a, b, c, d, ip;
+  const uint8_t *ip6;
+  char *result;
+
+  result = NEXT_BUFFER;
+  switch (addr->family) {
+    case IPADDR_UNSPEC:
+      snprintf(result, BUFFER_LENGTH, "[UNSPEC]");
+      break;
+    case IPADDR_INET4:
+      ip = addr->addr.in4;
+      a = (ip>>24) & 0xff;
+      b = (ip>>16) & 0xff;
+      c = (ip>> 8) & 0xff;
+      d = (ip>> 0) & 0xff;
+      snprintf(result, BUFFER_LENGTH, "%lu.%lu.%lu.%lu", a, b, c, d);
+      break;
+    case IPADDR_INET6:
+      ip6 = addr->addr.in6;
+#ifdef FEAT_IPV6
+      inet_ntop(AF_INET6, ip6, result, BUFFER_LENGTH);
+#else
+      assert(BUFFER_LENGTH >= 40);
+      for (a = 0; a < 8; a++)
+        snprintf(result + a * 5, 40 - a * 5, "%04x:",
+                 (unsigned int)(ip6[2 * a] << 8 | ip6[2 * a + 1]));
+#endif
+      break;
+    case IPADDR_ID:
+      snprintf(result, BUFFER_LENGTH, "ID#%010"PRIu32, addr->addr.id);
+      break;
+    default:
+      snprintf(result, BUFFER_LENGTH, "[UNKNOWN]");
+  }
+  return result;
+}
+
+/* ================================================== */
+
+int
+UTI_StringToIP(const char *addr, IPAddr *ip)
+{
+  struct in_addr in4;
+#ifdef FEAT_IPV6
+  struct in6_addr in6;
+#endif
+
+  if (inet_pton(AF_INET, addr, &in4) > 0) {
+    ip->family = IPADDR_INET4;
+    ip->_pad = 0;
+    ip->addr.in4 = ntohl(in4.s_addr);
+    return 1;
+  }
+
+#ifdef FEAT_IPV6
+  if (inet_pton(AF_INET6, addr, &in6) > 0) {
+    ip->family = IPADDR_INET6;
+    ip->_pad = 0;
+    memcpy(ip->addr.in6, in6.s6_addr, sizeof (ip->addr.in6));
+    return 1;
+  }
+#endif
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsStringIP(const char *string)
+{
+  IPAddr ip;
+
+  return UTI_StringToIP(string, &ip);
+}
+
+/* ================================================== */
+
+int
+UTI_StringToIdIP(const char *addr, IPAddr *ip)
+{
+  if (sscanf(addr, "ID#%"SCNu32, &ip->addr.id) == 1) {
+    ip->family = IPADDR_ID;
+    ip->_pad = 0;
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsIPReal(const IPAddr *ip)
+{
+  switch (ip->family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+      return 1;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+uint32_t
+UTI_IPToRefid(const IPAddr *ip)
+{
+  static int MD5_hash = -1;
+  unsigned char buf[16];
+
+  switch (ip->family) {
+    case IPADDR_INET4:
+      return ip->addr.in4;
+    case IPADDR_INET6:
+      if (MD5_hash < 0)
+        MD5_hash = HSH_GetHashId(HSH_MD5_NONCRYPTO);
+
+      if (MD5_hash < 0 ||
+          HSH_Hash(MD5_hash, (const unsigned char *)ip->addr.in6, sizeof (ip->addr.in6),
+                   NULL, 0, buf, sizeof (buf)) != sizeof (buf))
+        LOG_FATAL("Could not get MD5");
+
+      return (uint32_t)buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+uint32_t
+UTI_IPToHash(const IPAddr *ip)
+{
+  static uint32_t seed = 0;
+  const unsigned char *addr;
+  unsigned int i, len;
+  uint32_t hash;
+
+  switch (ip->family) {
+    case IPADDR_INET4:
+      addr = (unsigned char *)&ip->addr.in4;
+      len = sizeof (ip->addr.in4);
+      break;
+    case IPADDR_INET6:
+      addr = ip->addr.in6;
+      len = sizeof (ip->addr.in6);
+      break;
+    case IPADDR_ID:
+      addr = (unsigned char *)&ip->addr.id;
+      len = sizeof (ip->addr.id);
+      break;
+    default:
+      return 0;
+  }
+
+  /* Include a random seed in the hash to randomize collisions
+     and order of addresses in hash tables */
+  while (!seed)
+    UTI_GetRandomBytes(&seed, sizeof (seed));
+
+  for (i = 0, hash = seed; i < len; i++)
+    hash = 71 * hash + addr[i];
+
+  return hash + seed;
+}
+
+/* ================================================== */
+
+void
+UTI_IPHostToNetwork(const IPAddr *src, IPAddr *dest)
+{
+  /* Don't send uninitialized bytes over network */
+  memset(dest, 0, sizeof (IPAddr));
+
+  dest->family = htons(src->family);
+
+  switch (src->family) {
+    case IPADDR_INET4:
+      dest->addr.in4 = htonl(src->addr.in4);
+      break;
+    case IPADDR_INET6:
+      memcpy(dest->addr.in6, src->addr.in6, sizeof (dest->addr.in6));
+      break;
+    case IPADDR_ID:
+      dest->addr.id = htonl(src->addr.id);
+      break;
+    default:
+      dest->family = htons(IPADDR_UNSPEC);
+  }
+}
+
+/* ================================================== */
+
+void
+UTI_IPNetworkToHost(const IPAddr *src, IPAddr *dest)
+{
+  dest->family = ntohs(src->family);
+  dest->_pad = 0;
+
+  switch (dest->family) {
+    case IPADDR_INET4:
+      dest->addr.in4 = ntohl(src->addr.in4);
+      break;
+    case IPADDR_INET6:
+      memcpy(dest->addr.in6, src->addr.in6, sizeof (dest->addr.in6));
+      break;
+    case IPADDR_ID:
+      dest->addr.id = ntohl(src->addr.id);
+      break;
+    default:
+      dest->family = IPADDR_UNSPEC;
+  }
+}
+
+/* ================================================== */
+
+int
+UTI_CompareIPs(const IPAddr *a, const IPAddr *b, const IPAddr *mask)
+{
+  int i, d;
+
+  if (a->family != b->family)
+    return a->family - b->family;
+
+  if (mask && mask->family != b->family)
+    mask = NULL;
+
+  switch (a->family) {
+    case IPADDR_UNSPEC:
+      return 0;
+    case IPADDR_INET4:
+      if (mask)
+        return (a->addr.in4 & mask->addr.in4) - (b->addr.in4 & mask->addr.in4);
+      else
+        return a->addr.in4 - b->addr.in4;
+    case IPADDR_INET6:
+      for (i = 0, d = 0; !d && i < 16; i++) {
+        if (mask)
+          d = (a->addr.in6[i] & mask->addr.in6[i]) -
+              (b->addr.in6[i] & mask->addr.in6[i]);
+        else
+          d = a->addr.in6[i] - b->addr.in6[i];
+      }
+      return d;
+    case IPADDR_ID:
+      return a->addr.id - b->addr.id;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+char *
+UTI_IPSockAddrToString(const IPSockAddr *sa)
+{
+  char *result;
+
+  result = NEXT_BUFFER;
+  snprintf(result, BUFFER_LENGTH,
+           sa->ip_addr.family != IPADDR_INET6 ? "%s:%hu" : "[%s]:%hu",
+           UTI_IPToString(&sa->ip_addr), sa->port);
+
+  return result;
+}
+
+/* ================================================== */
+
+char *
+UTI_TimeToLogForm(time_t t)
+{
+  struct tm *stm;
+  char *result;
+
+  result = NEXT_BUFFER;
+
+  stm = gmtime(&t);
+
+  if (stm)
+    strftime(result, BUFFER_LENGTH, "%Y-%m-%d %H:%M:%S", stm);
+  else
+    snprintf(result, BUFFER_LENGTH, "INVALID    INVALID ");
+
+  return result;
+}
+
+/* ================================================== */
+
+void
+UTI_AdjustTimespec(const struct timespec *old_ts, const struct timespec *when,
+                   struct timespec *new_ts, double *delta_time, double dfreq, double doffset)
+{
+  double elapsed;
+
+  elapsed = UTI_DiffTimespecsToDouble(when, old_ts);
+  *delta_time = elapsed * dfreq - doffset;
+  UTI_AddDoubleToTimespec(old_ts, *delta_time, new_ts);
+}
+
+/* ================================================== */
+
+void
+UTI_GetNtp64Fuzz(NTP_int64 *ts, int precision)
+{
+  int start, bits;
+
+  assert(precision >= -32 && precision <= 32);
+  assert(sizeof (*ts) == 8);
+
+  start = sizeof (*ts) - (precision + 32 + 7) / 8;
+  ts->hi = ts->lo = 0;
+
+  UTI_GetRandomBytes((unsigned char *)ts + start, sizeof (*ts) - start);
+
+  bits = (precision + 32) % 8;
+  if (bits)
+    ((unsigned char *)ts)[start] %= 1U << bits;
+}
+
+/* ================================================== */
+
+double
+UTI_Ntp32ToDouble(NTP_int32 x)
+{
+  return (double) ntohl(x) / 65536.0;
+}
+
+/* ================================================== */
+
+#define MAX_NTP_INT32 (4294967295.0 / 65536.0)
+
+NTP_int32
+UTI_DoubleToNtp32(double x)
+{
+  NTP_int32 r;
+
+  if (x >= MAX_NTP_INT32) {
+    r = 0xffffffff;
+  } else if (x <= 0.0) {
+    r = 0;
+  } else {
+    x *= 65536.0;
+    r = x;
+
+    /* Round up */
+    if (r < x)
+      r++;
+  }
+
+  return htonl(r);
+}
+
+/* ================================================== */
+
+double
+UTI_Ntp32f28ToDouble(NTP_int32 x)
+{
+  uint32_t r = ntohl(x);
+
+  /* Maximum value is special */
+  if (r == 0xffffffff)
+    return MAX_NTP_INT32;
+
+  return r / (double)(1U << 28);
+}
+
+/* ================================================== */
+
+NTP_int32
+UTI_DoubleToNtp32f28(double x)
+{
+  NTP_int32 r;
+
+  if (x >= 4294967295.0 / (1U << 28)) {
+    r = 0xffffffff;
+  } else if (x <= 0.0) {
+    r = 0;
+  } else {
+    x *= 1U << 28;
+    r = x;
+
+    /* Round up */
+    if (r < x)
+      r++;
+  }
+
+  return htonl(r);
+}
+
+/* ================================================== */
+
+void
+UTI_ZeroNtp64(NTP_int64 *ts)
+{
+  ts->hi = ts->lo = htonl(0);
+}
+
+/* ================================================== */
+
+int
+UTI_IsZeroNtp64(const NTP_int64 *ts)
+{
+  return !ts->hi && !ts->lo;
+}
+
+/* ================================================== */
+
+int
+UTI_CompareNtp64(const NTP_int64 *a, const NTP_int64 *b)
+{
+  int32_t diff;
+
+  if (a->hi == b->hi && a->lo == b->lo)
+    return 0;
+
+  diff = ntohl(a->hi) - ntohl(b->hi);
+
+  if (diff < 0)
+    return -1;
+  if (diff > 0)
+    return 1;
+
+  return ntohl(a->lo) < ntohl(b->lo) ? -1 : 1;
+}
+
+/* ================================================== */
+
+int
+UTI_IsEqualAnyNtp64(const NTP_int64 *a, const NTP_int64 *b1, const NTP_int64 *b2,
+                    const NTP_int64 *b3)
+{
+  if (b1 && a->lo == b1->lo && a->hi == b1->hi)
+    return 1;
+
+  if (b2 && a->lo == b2->lo && a->hi == b2->hi)
+    return 1;
+
+  if (b3 && a->lo == b3->lo && a->hi == b3->hi)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+/* Seconds part of NTP timestamp correponding to the origin of the time_t format */
+#define JAN_1970 0x83aa7e80UL
+
+#define NSEC_PER_NTP64 4.294967296
+
+void
+UTI_TimespecToNtp64(const struct timespec *src, NTP_int64 *dest, const NTP_int64 *fuzz)
+{
+  uint32_t hi, lo, sec, nsec;
+
+  sec = (uint32_t)src->tv_sec;
+  nsec = (uint32_t)src->tv_nsec;
+
+  /* Recognize zero as a special case - it always signifies
+     an 'unknown' value */
+  if (!nsec && !sec) {
+    hi = lo = 0;
+  } else {
+    hi = htonl(sec + JAN_1970);
+    lo = htonl(NSEC_PER_NTP64 * nsec);
+
+    /* Add the fuzz */
+    if (fuzz) {
+      hi ^= fuzz->hi;
+      lo ^= fuzz->lo;
+    }
+  }
+
+  dest->hi = hi;
+  dest->lo = lo;
+}
+
+/* ================================================== */
+
+void
+UTI_Ntp64ToTimespec(const NTP_int64 *src, struct timespec *dest)
+{
+  uint32_t ntp_sec, ntp_frac;
+
+  /* Zero is a special value */
+  if (UTI_IsZeroNtp64(src)) {
+    UTI_ZeroTimespec(dest);
+    return;
+  }
+
+  ntp_sec = ntohl(src->hi);
+  ntp_frac = ntohl(src->lo);
+
+#ifdef HAVE_LONG_TIME_T
+  dest->tv_sec = ntp_sec - (uint32_t)(NTP_ERA_SPLIT + JAN_1970) +
+                 (time_t)NTP_ERA_SPLIT;
+#else
+  dest->tv_sec = ntp_sec - JAN_1970;
+#endif
+
+  dest->tv_nsec = ntp_frac / NSEC_PER_NTP64;
+}
+
+/* ================================================== */
+
+double
+UTI_DiffNtp64ToDouble(const NTP_int64 *a, const NTP_int64 *b)
+{
+  /* Don't convert to timespec to allow any epoch */
+  return (int32_t)(ntohl(a->hi) - ntohl(b->hi)) +
+         ((double)ntohl(a->lo) - (double)ntohl(b->lo)) / (1.0e9 * NSEC_PER_NTP64);
+}
+
+/* ================================================== */
+
+/* Maximum offset between two sane times */
+#define MAX_OFFSET 4294967296.0
+
+/* Minimum allowed distance from maximum 32-bit time_t */
+#define MIN_ENDOFTIME_DISTANCE (365 * 24 * 3600)
+
+int
+UTI_IsTimeOffsetSane(const struct timespec *ts, double offset)
+{
+  double t;
+
+  /* Handle nan correctly here */
+  if (!(offset > -MAX_OFFSET && offset < MAX_OFFSET))
+    return 0;
+
+  t = UTI_TimespecToDouble(ts) + offset;
+
+  /* Time before 1970 is not considered valid */
+  if (t < 0.0)
+    return 0;
+
+#ifdef HAVE_LONG_TIME_T
+  /* Check if it's in the interval to which NTP time is mapped */
+  if (t < (double)NTP_ERA_SPLIT || t > (double)(NTP_ERA_SPLIT + (1LL << 32)))
+    return 0;
+#else
+  /* Don't get too close to 32-bit time_t overflow */
+  if (t > (double)(0x7fffffff - MIN_ENDOFTIME_DISTANCE))
+    return 0;
+#endif
+
+  return 1;
+}
+
+/* ================================================== */
+
+double
+UTI_Log2ToDouble(int l)
+{
+  if (l >= 0) {
+    if (l > 31)
+      l = 31;
+    return (uint32_t)1 << l;
+  } else {
+    if (l < -31)
+      l = -31;
+    return 1.0 / ((uint32_t)1 << -l);
+  }
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecNetworkToHost(const Timespec *src, struct timespec *dest)
+{
+  uint32_t sec_low, nsec;
+#ifdef HAVE_LONG_TIME_T
+  uint32_t sec_high;
+#endif
+
+  sec_low = ntohl(src->tv_sec_low);
+#ifdef HAVE_LONG_TIME_T
+  sec_high = ntohl(src->tv_sec_high);
+  if (sec_high == TV_NOHIGHSEC)
+    sec_high = 0;
+
+  dest->tv_sec = (uint64_t)sec_high << 32 | sec_low;
+#else
+  dest->tv_sec = sec_low;
+#endif
+
+  nsec = ntohl(src->tv_nsec);
+  dest->tv_nsec = MIN(nsec, 999999999U);
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecHostToNetwork(const struct timespec *src, Timespec *dest)
+{
+  dest->tv_nsec = htonl(src->tv_nsec);
+#ifdef HAVE_LONG_TIME_T
+  dest->tv_sec_high = htonl((uint64_t)src->tv_sec >> 32);
+#else
+  dest->tv_sec_high = htonl(TV_NOHIGHSEC);
+#endif
+  dest->tv_sec_low = htonl(src->tv_sec);
+}
+
+/* ================================================== */
+
+#define FLOAT_EXP_BITS 7
+#define FLOAT_EXP_MIN (-(1 << (FLOAT_EXP_BITS - 1)))
+#define FLOAT_EXP_MAX (-FLOAT_EXP_MIN - 1)
+#define FLOAT_COEF_BITS ((int)sizeof (int32_t) * 8 - FLOAT_EXP_BITS)
+#define FLOAT_COEF_MIN (-(1 << (FLOAT_COEF_BITS - 1)))
+#define FLOAT_COEF_MAX (-FLOAT_COEF_MIN - 1)
+
+double
+UTI_FloatNetworkToHost(Float f)
+{
+  int32_t exp, coef;
+  uint32_t x;
+
+  x = ntohl(f.f);
+
+  exp = x >> FLOAT_COEF_BITS;
+  if (exp >= 1 << (FLOAT_EXP_BITS - 1))
+      exp -= 1 << FLOAT_EXP_BITS;
+  exp -= FLOAT_COEF_BITS;
+
+  coef = x % (1U << FLOAT_COEF_BITS);
+  if (coef >= 1 << (FLOAT_COEF_BITS - 1))
+      coef -= 1 << FLOAT_COEF_BITS;
+
+  return coef * pow(2.0, exp);
+}
+
+Float
+UTI_FloatHostToNetwork(double x)
+{
+  int32_t exp, coef, neg;
+  Float f;
+
+  if (x < 0.0) {
+    x = -x;
+    neg = 1;
+  } else if (x >= 0.0) {
+    neg = 0;
+  } else {
+    /* Save NaN as zero */
+    x = 0.0;
+    neg = 0;
+  }
+
+  if (x < 1.0e-100) {
+    exp = coef = 0;
+  } else if (x > 1.0e100) {
+    exp = FLOAT_EXP_MAX;
+    coef = FLOAT_COEF_MAX + neg;
+  } else {
+    exp = log(x) / log(2) + 1;
+    coef = x * pow(2.0, -exp + FLOAT_COEF_BITS) + 0.5;
+
+    assert(coef > 0);
+
+    /* we may need to shift up to two bits down */
+    while (coef > FLOAT_COEF_MAX + neg) {
+      coef >>= 1;
+      exp++;
+    }
+
+    if (exp > FLOAT_EXP_MAX) {
+      /* overflow */
+      exp = FLOAT_EXP_MAX;
+      coef = FLOAT_COEF_MAX + neg;
+    } else if (exp < FLOAT_EXP_MIN) {
+      /* underflow */
+      if (exp + FLOAT_COEF_BITS >= FLOAT_EXP_MIN) {
+        coef >>= FLOAT_EXP_MIN - exp;
+        exp = FLOAT_EXP_MIN;
+      } else {
+        exp = coef = 0;
+      }
+    }
+  }
+
+  /* negate back */
+  if (neg)
+    coef = (uint32_t)-coef << FLOAT_EXP_BITS >> FLOAT_EXP_BITS;
+
+  f.f = htonl((uint32_t)exp << FLOAT_COEF_BITS | coef);
+  return f;
+}
+
+/* ================================================== */
+
+CMC_Algorithm
+UTI_CmacNameToAlgorithm(const char *name)
+{
+  if (strcmp(name, "AES128") == 0)
+    return CMC_AES128;
+  else if (strcmp(name, "AES256") == 0)
+    return CMC_AES256;
+  return CMC_INVALID;
+}
+
+/* ================================================== */
+
+HSH_Algorithm
+UTI_HashNameToAlgorithm(const char *name)
+{
+  if (strcmp(name, "MD5") == 0)
+    return HSH_MD5;
+  else if (strcmp(name, "SHA1") == 0)
+    return HSH_SHA1;
+  else if (strcmp(name, "SHA256") == 0)
+    return HSH_SHA256;
+  else if (strcmp(name, "SHA384") == 0)
+    return HSH_SHA384;
+  else if (strcmp(name, "SHA512") == 0)
+    return HSH_SHA512;
+  else if (strcmp(name, "SHA3-224") == 0)
+    return HSH_SHA3_224;
+  else if (strcmp(name, "SHA3-256") == 0)
+    return HSH_SHA3_256;
+  else if (strcmp(name, "SHA3-384") == 0)
+    return HSH_SHA3_384;
+  else if (strcmp(name, "SHA3-512") == 0)
+    return HSH_SHA3_512;
+  else if (strcmp(name, "TIGER") == 0)
+    return HSH_TIGER;
+  else if (strcmp(name, "WHIRLPOOL") == 0)
+    return HSH_WHIRLPOOL;
+  return HSH_INVALID;
+}
+
+/* ================================================== */
+
+int
+UTI_FdSetCloexec(int fd)
+{
+  int flags;
+
+  flags = fcntl(fd, F_GETFD);
+  if (flags == -1) {
+    DEBUG_LOG("fcntl() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  flags |= FD_CLOEXEC;
+
+  if (fcntl(fd, F_SETFD, flags) < 0) {
+    DEBUG_LOG("fcntl() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+UTI_SetQuitSignalsHandler(void (*handler)(int), int ignore_sigpipe)
+{
+  struct sigaction sa;
+
+  sa.sa_handler = handler;
+  sa.sa_flags = SA_RESTART;
+  if (sigemptyset(&sa.sa_mask) < 0)
+    LOG_FATAL("sigemptyset() failed");
+
+#ifdef SIGINT
+  if (sigaction(SIGINT, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGINT);
+#endif
+#ifdef SIGTERM
+  if (sigaction(SIGTERM, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGTERM);
+#endif
+#ifdef SIGQUIT
+  if (sigaction(SIGQUIT, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGQUIT);
+#endif
+#ifdef SIGHUP
+  if (sigaction(SIGHUP, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGHUP);
+#endif
+
+  if (ignore_sigpipe)
+    sa.sa_handler = SIG_IGN;
+
+  if (sigaction(SIGPIPE, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGPIPE);
+}
+
+/* ================================================== */
+
+char *
+UTI_PathToDir(const char *path)
+{
+  char *dir, *slash;
+  size_t dir_len;
+
+  slash = strrchr(path, '/');
+
+  if (!slash)
+    return Strdup(".");
+
+  if (slash == path)
+    return Strdup("/");
+
+  dir_len = slash - path;
+
+  dir = Malloc(dir_len + 1);
+  memcpy(dir, path, dir_len);
+  dir[dir_len] = '\0';
+
+  return dir;
+}
+
+/* ================================================== */
+
+static int
+create_dir(char *p, mode_t mode, uid_t uid, gid_t gid)
+{
+  int status;
+  struct stat buf;
+
+  /* See if directory exists */
+  status = stat(p, &buf);
+
+  if (status < 0) {
+    if (errno != ENOENT) {
+      LOG(LOGS_ERR, "Could not access %s : %s", p, strerror(errno));
+      return 0;
+    }
+  } else {
+    if (S_ISDIR(buf.st_mode))
+      return 1;
+    LOG(LOGS_ERR, "%s is not directory", p);
+    return 0;
+  }
+
+  /* Create the directory */
+  if (mkdir(p, mode) < 0) {
+    LOG(LOGS_ERR, "Could not create directory %s : %s", p, strerror(errno));
+    return 0;
+  }
+
+  /* Set its owner */
+  if (chown(p, uid, gid) < 0) {
+    LOG(LOGS_ERR, "Could not change ownership of %s : %s", p, strerror(errno));
+    /* Don't leave it there with incorrect ownership */
+    rmdir(p);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+/* Return 0 if the directory couldn't be created, 1 if it could (or
+   already existed) */
+int
+UTI_CreateDirAndParents(const char *path, mode_t mode, uid_t uid, gid_t gid)
+{
+  char *p;
+  int i, j, k, last;
+
+  /* Don't try to create current directory */
+  if (!strcmp(path, "."))
+    return 1;
+
+  p = (char *)Malloc(1 + strlen(path));
+
+  i = k = 0;
+  while (1) {
+    p[i++] = path[k++];
+
+    if (path[k] == '/' || !path[k]) {
+      /* Check whether its end of string, a trailing / or group of / */
+      last = 1;
+      j = k;
+      while (path[j]) {
+        if (path[j] != '/') {
+          /* Pick up a / into p[] thru the assignment at the top of the loop */
+          k = j - 1;
+          last = 0;
+          break;
+        }
+        j++;
+      }
+
+      p[i] = 0;
+
+      if (!create_dir(p, last ? mode : 0755, last ? uid : 0, last ? gid : 0)) {
+        Free(p);
+        return 0;
+      }
+
+      if (last)
+        break;
+    }
+
+    if (!path[k])
+      break;
+  }
+
+  Free(p);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+UTI_CheckDirPermissions(const char *path, mode_t perm, uid_t uid, gid_t gid)
+{
+  struct stat buf;
+
+  if (stat(path, &buf)) {
+    LOG(LOGS_ERR, "Could not access %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  if (!S_ISDIR(buf.st_mode)) {
+    LOG(LOGS_ERR, "%s is not directory", path);
+    return 0;
+  }
+
+  if ((buf.st_mode & 0777) & ~perm) {
+    LOG(LOGS_ERR, "Wrong permissions on %s", path);
+    return 0;
+  }
+
+  if (buf.st_uid != uid) {
+    LOG(LOGS_ERR, "Wrong owner of %s (%s != %u)", path, "UID", uid);
+    return 0;
+  }
+
+  if (buf.st_gid != gid) {
+    LOG(LOGS_ERR, "Wrong owner of %s (%s != %u)", path, "GID", gid);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+join_path(const char *basedir, const char *name, const char *suffix,
+          char *buffer, size_t length, LOG_Severity severity)
+{
+  const char *sep;
+
+  if (!basedir) {
+    basedir = "";
+    sep = "";
+  } else {
+    sep = "/";
+  }
+
+  if (!suffix)
+    suffix = "";
+
+  if (snprintf(buffer, length, "%s%s%s%s", basedir, sep, name, suffix) >= length) {
+    LOG(severity, "File path %s%s%s%s too long", basedir, sep, name, suffix);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+FILE *
+UTI_OpenFile(const char *basedir, const char *name, const char *suffix,
+             char mode, mode_t perm)
+{
+  const char *file_mode;
+  char path[PATH_MAX];
+  LOG_Severity severity;
+  int fd, flags;
+  FILE *file;
+
+  severity = mode >= 'A' && mode <= 'Z' ? LOGS_FATAL : LOGS_ERR;
+
+  if (!join_path(basedir, name, suffix, path, sizeof (path), severity))
+    return NULL;
+
+  switch (mode) {
+    case 'r':
+    case 'R':
+      flags = O_RDONLY;
+      file_mode = "r";
+      if (severity != LOGS_FATAL)
+        severity = LOGS_DEBUG;
+      break;
+    case 'w':
+    case 'W':
+      flags = O_WRONLY | O_CREAT | O_EXCL;
+      file_mode = "w";
+      break;
+    case 'a':
+    case 'A':
+      flags = O_WRONLY | O_CREAT | O_APPEND | O_NOFOLLOW;
+      file_mode = "a";
+      break;
+    default:
+      assert(0);
+      return NULL;
+  }
+
+try_again:
+  fd = open(path, flags, perm);
+  if (fd < 0) {
+    if (errno == EEXIST) {
+      if (unlink(path) < 0) {
+        LOG(severity, "Could not remove %s : %s", path, strerror(errno));
+        return NULL;
+      }
+      DEBUG_LOG("Removed %s", path);
+      goto try_again;
+    }
+    LOG(severity, "Could not open %s : %s", path, strerror(errno));
+    return NULL;
+  }
+
+  UTI_FdSetCloexec(fd);
+
+  file = fdopen(fd, file_mode);
+  if (!file) {
+    LOG(severity, "Could not open %s : %s", path, strerror(errno));
+    close(fd);
+    return NULL;
+  }
+
+  DEBUG_LOG("Opened %s fd=%d mode=%c", path, fd, mode);
+
+  return file;
+}
+
+/* ================================================== */
+
+int
+UTI_RenameTempFile(const char *basedir, const char *name,
+                   const char *old_suffix, const char *new_suffix)
+{
+  char old_path[PATH_MAX], new_path[PATH_MAX];
+
+  if (!join_path(basedir, name, old_suffix, old_path, sizeof (old_path), LOGS_ERR))
+    return 0;
+
+  if (!join_path(basedir, name, new_suffix, new_path, sizeof (new_path), LOGS_ERR))
+    goto error;
+
+  if (rename(old_path, new_path) < 0) {
+    LOG(LOGS_ERR, "Could not replace %s with %s : %s", new_path, old_path, strerror(errno));
+    goto error;
+  }
+
+  DEBUG_LOG("Renamed %s to %s", old_path, new_path);
+
+  return 1;
+
+error:
+  if (unlink(old_path) < 0)
+    LOG(LOGS_ERR, "Could not remove %s : %s", old_path, strerror(errno));
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_RemoveFile(const char *basedir, const char *name, const char *suffix)
+{
+  char path[PATH_MAX];
+  struct stat buf;
+
+  if (!join_path(basedir, name, suffix, path, sizeof (path), LOGS_ERR))
+    return 0;
+
+  /* Avoid logging an error message if the file is not accessible */
+  if (stat(path, &buf) < 0) {
+    DEBUG_LOG("Could not remove %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  if (unlink(path) < 0) {
+    LOG(LOGS_ERR, "Could not remove %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  DEBUG_LOG("Removed %s", path);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+UTI_DropRoot(uid_t uid, gid_t gid)
+{
+  /* Drop supplementary groups */
+  if (setgroups(0, NULL))
+    LOG_FATAL("setgroups() failed : %s", strerror(errno));
+
+  /* Set effective, saved and real group ID */
+  if (setgid(gid))
+    LOG_FATAL("setgid(%u) failed : %s", gid, strerror(errno));
+
+  /* Set effective, saved and real user ID */
+  if (setuid(uid))
+    LOG_FATAL("setuid(%u) failed : %s", uid, strerror(errno));
+
+  DEBUG_LOG("Dropped root privileges: UID %u GID %u", uid, gid);
+}
+
+/* ================================================== */
+
+#define DEV_URANDOM "/dev/urandom"
+
+static FILE *urandom_file = NULL;
+
+void
+UTI_GetRandomBytesUrandom(void *buf, unsigned int len)
+{
+  if (!urandom_file)
+    urandom_file = UTI_OpenFile(NULL, DEV_URANDOM, NULL, 'R', 0);
+  if (fread(buf, 1, len, urandom_file) != len)
+    LOG_FATAL("Can't read from %s", DEV_URANDOM);
+}
+
+/* ================================================== */
+
+#ifdef HAVE_GETRANDOM
+
+static unsigned int getrandom_buf_available = 0;
+
+static void
+get_random_bytes_getrandom(char *buf, unsigned int len)
+{
+  static char rand_buf[256];
+  static unsigned int disabled = 0;
+  unsigned int i;
+
+  for (i = 0; i < len; i++) {
+    if (getrandom_buf_available == 0) {
+      if (disabled)
+        break;
+
+      if (getrandom(rand_buf, sizeof (rand_buf), GRND_NONBLOCK) != sizeof (rand_buf)) {
+        disabled = 1;
+        break;
+      }
+
+      getrandom_buf_available = sizeof (rand_buf);
+    }
+
+    buf[i] = rand_buf[--getrandom_buf_available];
+  }
+
+  if (i < len)
+    UTI_GetRandomBytesUrandom(buf, len);
+}
+#endif
+
+/* ================================================== */
+
+void
+UTI_GetRandomBytes(void *buf, unsigned int len)
+{
+#ifdef HAVE_ARC4RANDOM
+  arc4random_buf(buf, len);
+#elif defined(HAVE_GETRANDOM)
+  get_random_bytes_getrandom(buf, len);
+#else
+  UTI_GetRandomBytesUrandom(buf, len);
+#endif
+}
+
+/* ================================================== */
+
+void
+UTI_ResetGetRandomFunctions(void)
+{
+  if (urandom_file) {
+    fclose(urandom_file);
+    urandom_file = NULL;
+  }
+#ifdef HAVE_GETRANDOM
+  getrandom_buf_available = 0;
+#endif
+}
+
+/* ================================================== */
+
+int
+UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len)
+{
+  unsigned int i, l;
+
+  if (hex_len < 1)
+    return 0;
+
+  hex[0] = '\0';
+
+  for (i = l = 0; i < buf_len; i++, l += 2) {
+    if (l + 2 >= hex_len ||
+        snprintf(hex + l, hex_len - l, "%02hhX", ((const char *)buf)[i]) != 2)
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+unsigned int
+UTI_HexToBytes(const char *hex, void *buf, unsigned int len)
+{
+  char *p, byte[3];
+  unsigned int i;
+
+  for (i = 0; i < len && *hex != '\0'; i++) {
+    byte[0] = *hex++;
+    if (*hex == '\0')
+      return 0;
+    byte[1] = *hex++;
+    byte[2] = '\0';
+    ((char *)buf)[i] = strtol(byte, &p, 16);
+
+    if (p != byte + 2)
+      return 0;
+  }
+
+  return *hex == '\0' ? i : 0;
+}
+
+/* ================================================== */
+
+int
+UTI_SplitString(char *string, char **words, int max_saved_words)
+{
+  char *s = string;
+  int i;
+
+  for (i = 0; i < max_saved_words; i++)
+    words[i] = NULL;
+
+  for (i = 0; ; i++) {
+    /* Zero white-space characters before the word */
+    while (*s != '\0' && isspace((unsigned char)*s))
+      *s++ = '\0';
+
+    if (*s == '\0')
+      break;
+
+    if (i < max_saved_words)
+      words[i] = s;
+
+    /* Find the next word */
+    while (*s != '\0' && !isspace((unsigned char)*s))
+      s++;
+  }
+
+  return i;
+}
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..a57ef9b
--- /dev/null
+++ b/util.h
@@ -0,0 +1,258 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Various utility functions
+  */
+
+#ifndef GOT_UTIL_H
+#define GOT_UTIL_H
+
+#include "sysincl.h"
+
+#include "addressing.h"
+#include "ntp.h"
+#include "candm.h"
+#include "cmac.h"
+#include "hash.h"
+
+/* Zero a timespec */
+extern void UTI_ZeroTimespec(struct timespec *ts);
+
+/* Check if a timespec is zero */
+extern int UTI_IsZeroTimespec(struct timespec *ts);
+
+/* Convert a timeval into a timespec */
+extern void UTI_TimevalToTimespec(const struct timeval *tv, struct timespec *ts);
+
+/* Convert a timespec into a timeval */
+extern void UTI_TimespecToTimeval(const struct timespec *ts, struct timeval *tv);
+
+/* Convert a timespec into a floating point number of seconds */
+extern double UTI_TimespecToDouble(const struct timespec *ts);
+
+/* Convert a number of seconds expressed in floating point into a
+   timespec */
+extern void UTI_DoubleToTimespec(double d, struct timespec *ts);
+
+/* Normalise a timespec, by adding or subtracting seconds to bring
+   its nanosecond field into range */
+extern void UTI_NormaliseTimespec(struct timespec *ts);
+
+/* Convert a timeval into a floating point number of seconds */
+extern double UTI_TimevalToDouble(const struct timeval *tv);
+
+/* Convert a number of seconds expressed in floating point into a
+   timeval */
+extern void UTI_DoubleToTimeval(double a, struct timeval *b);
+
+/* Normalise a struct timeval, by adding or subtracting seconds to bring
+   its microseconds field into range */
+extern void UTI_NormaliseTimeval(struct timeval *x);
+
+/* Returns -1 if a comes earlier than b, 0 if a is the same time as b,
+   and +1 if a comes after b */
+extern int UTI_CompareTimespecs(const struct timespec *a, const struct timespec *b);
+
+/* Calculate result = a - b */
+extern void UTI_DiffTimespecs(struct timespec *result,
+                              const struct timespec *a, const struct timespec *b);
+
+/* Calculate result = a - b and return as a double */
+extern double UTI_DiffTimespecsToDouble(const struct timespec *a, const struct timespec *b);
+
+/* Add a double increment to a timespec to get a new one. 'start' is
+   the starting time, 'end' is the result that we return.  This is
+   safe to use if start and end are the same */
+extern void UTI_AddDoubleToTimespec(const struct timespec *start, double increment,
+                                    struct timespec *end);
+
+/* Calculate the average and difference (as a double) of two timespecs */
+extern void UTI_AverageDiffTimespecs(const struct timespec *earlier, const struct timespec *later,
+                                     struct timespec *average, double *diff);
+
+/* Calculate result = a - b + c */
+extern void UTI_AddDiffToTimespec(const struct timespec *a, const struct timespec *b,
+                                  const struct timespec *c, struct timespec *result);
+
+/* Convert a timespec into a temporary string, largely for diagnostic
+   display */
+extern char *UTI_TimespecToString(const struct timespec *ts);
+
+/* Convert an NTP timestamp into a temporary string, largely for
+   diagnostic display */
+extern char *UTI_Ntp64ToString(const NTP_int64 *ts);
+
+/* Convert ref_id into a temporary string, for diagnostics */
+extern char *UTI_RefidToString(uint32_t ref_id);
+
+/* Convert an IP address to string, for diagnostics */
+extern char *UTI_IPToString(const IPAddr *ip);
+
+extern int UTI_StringToIP(const char *addr, IPAddr *ip);
+extern int UTI_IsStringIP(const char *string);
+extern int UTI_StringToIdIP(const char *addr, IPAddr *ip);
+extern int UTI_IsIPReal(const IPAddr *ip);
+extern uint32_t UTI_IPToRefid(const IPAddr *ip);
+extern uint32_t UTI_IPToHash(const IPAddr *ip);
+extern void UTI_IPHostToNetwork(const IPAddr *src, IPAddr *dest);
+extern void UTI_IPNetworkToHost(const IPAddr *src, IPAddr *dest);
+extern int UTI_CompareIPs(const IPAddr *a, const IPAddr *b, const IPAddr *mask);
+
+extern char *UTI_IPSockAddrToString(const IPSockAddr *sa);
+
+extern char *UTI_TimeToLogForm(time_t t);
+
+/* Adjust time following a frequency/offset change */
+extern void UTI_AdjustTimespec(const struct timespec *old_ts, const struct timespec *when,
+                               struct timespec *new_ts, double *delta_time,
+                               double dfreq, double doffset);
+
+/* Get zero NTP timestamp with random bits below precision */
+extern void UTI_GetNtp64Fuzz(NTP_int64 *ts, int precision);
+
+extern double UTI_Ntp32ToDouble(NTP_int32 x);
+extern NTP_int32 UTI_DoubleToNtp32(double x);
+
+extern double UTI_Ntp32f28ToDouble(NTP_int32 x);
+extern NTP_int32 UTI_DoubleToNtp32f28(double x);
+
+/* Zero an NTP timestamp */
+extern void UTI_ZeroNtp64(NTP_int64 *ts);
+
+/* Check if an NTP timestamp is zero */
+extern int UTI_IsZeroNtp64(const NTP_int64 *ts);
+
+/* Compare two NTP timestamps.  Returns -1 if a is before b, 0 if a is equal to
+   b, and 1 if a is after b. */
+extern int UTI_CompareNtp64(const NTP_int64 *a, const NTP_int64 *b);
+
+/* Compare an NTP timestamp with up to three other timestamps.  Returns 0
+   if a is not equal to any of b1, b2, and b3, 1 otherwise. */
+extern int UTI_IsEqualAnyNtp64(const NTP_int64 *a, const NTP_int64 *b1,
+                               const NTP_int64 *b2, const NTP_int64 *b3);
+
+/* Convert a timespec into an NTP timestamp */
+extern void UTI_TimespecToNtp64(const struct timespec *src, NTP_int64 *dest,
+                                const NTP_int64 *fuzz);
+
+/* Convert an NTP timestamp into a timespec */
+extern void UTI_Ntp64ToTimespec(const NTP_int64 *src, struct timespec *dest);
+
+/* Calculate a - b in any epoch */
+extern double UTI_DiffNtp64ToDouble(const NTP_int64 *a, const NTP_int64 *b);
+
+/* Check if time + offset is sane */
+extern int UTI_IsTimeOffsetSane(const struct timespec *ts, double offset);
+
+/* Get 2 raised to power of a signed integer */
+extern double UTI_Log2ToDouble(int l);
+
+extern void UTI_TimespecNetworkToHost(const Timespec *src, struct timespec *dest);
+extern void UTI_TimespecHostToNetwork(const struct timespec *src, Timespec *dest);
+
+extern double UTI_FloatNetworkToHost(Float x);
+extern Float UTI_FloatHostToNetwork(double x);
+
+extern CMC_Algorithm UTI_CmacNameToAlgorithm(const char *name);
+extern HSH_Algorithm UTI_HashNameToAlgorithm(const char *name);
+
+/* Set FD_CLOEXEC on descriptor */
+extern int UTI_FdSetCloexec(int fd);
+
+extern void UTI_SetQuitSignalsHandler(void (*handler)(int), int ignore_sigpipe);
+
+/* Get directory (as an allocated string) for a path */
+extern char *UTI_PathToDir(const char *path);
+
+/* Create a directory with a specified mode (umasked) and set its uid/gid.
+   Create also any parent directories that don't exist with mode 755 and
+   default uid/gid.  Returns 1 if created or already exists (even with
+   different mode/uid/gid), 0 otherwise. */
+extern int UTI_CreateDirAndParents(const char *path, mode_t mode, uid_t uid, gid_t gid);
+
+/* Check if a directory is secure.  It must not have other than the specified
+   permissions and its uid/gid must match the specified values. */
+extern int UTI_CheckDirPermissions(const char *path, mode_t perm, uid_t uid, gid_t gid);
+
+/* Open a file.  The full path of the file is constructed from the basedir
+   (may be NULL), '/' (if basedir is not NULL), name, and suffix (may be NULL).
+   Created files have specified permissions (umasked).  Returns NULL on error.
+   The following modes are supported (if the mode is an uppercase character,
+   errors are fatal):
+   r/R - open an existing file for reading
+   w/W - open a new file for writing (remove existing file)
+   a/A - open an existing file for appending (create if does not exist) */
+extern FILE *UTI_OpenFile(const char *basedir, const char *name, const char *suffix,
+                          char mode, mode_t perm);
+
+/* Rename a temporary file by changing its suffix.  The paths are constructed as
+   in UTI_OpenFile().  If the renaming fails, the file will be removed. */
+extern int UTI_RenameTempFile(const char *basedir, const char *name,
+                              const char *old_suffix, const char *new_suffix);
+
+/* Remove a file.  The path is constructed as in UTI_OpenFile(). */
+extern int UTI_RemoveFile(const char *basedir, const char *name, const char *suffix);
+
+/* Set process user/group IDs and drop supplementary groups */
+extern void UTI_DropRoot(uid_t uid, gid_t gid);
+
+/* Fill buffer with random bytes from /dev/urandom */
+extern void UTI_GetRandomBytesUrandom(void *buf, unsigned int len);
+
+/* Fill buffer with random bytes from /dev/urandom or a faster source if it's
+   available (e.g. arc4random()), which may not necessarily be suitable for
+   generating long-term keys */
+extern void UTI_GetRandomBytes(void *buf, unsigned int len);
+
+/* Close /dev/urandom and drop any cached data used by the GetRandom functions
+   to prevent forked processes getting the same sequence of random numbers */
+extern void UTI_ResetGetRandomFunctions(void);
+
+/* Print data in hexadecimal format */
+extern int UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len);
+
+/* Parse a string containing data in hexadecimal format.  In-place conversion
+   is supported. */
+extern unsigned int UTI_HexToBytes(const char *hex, void *buf, unsigned int len);
+
+/* Split a string into words separated by whitespace characters.  It returns
+   the number of words found in the string, but saves only up to the specified
+   number of pointers to the words. */
+extern int UTI_SplitString(char *string, char **words, int max_saved_words);
+
+/* Macros to get maximum and minimum of two values */
+#ifdef MAX
+#undef MAX
+#endif
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#ifdef MIN
+#undef MIN
+#endif
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+
+/* Macro to clamp a value between two values */
+#define CLAMP(min, x, max) (MAX((min), MIN((x), (max))))
+
+#define SQUARE(x) ((x) * (x))
+
+#endif /* GOT_UTIL_H */
diff --git a/version.txt b/version.txt
new file mode 100644
index 0000000..69df05f
--- /dev/null
+++ b/version.txt
@@ -0,0 +1 @@
+4.3
-- 
cgit v1.2.3


From b4f11fdbc00d1d23c59dc4ff3062fb7852d3f79f Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 31 Aug 2022 13:32:14 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 547ce83..203c102 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -10,7 +10,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
-- 
cgit v1.2.3


From a465f66f766dfe66f46edbb0e3d69e476cc8d96f Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Fri, 27 Jan 2023 22:51:17 +0100
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 547ce83..203c102 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -10,7 +10,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
-- 
cgit v1.2.3


From 83e6eb02dcbb2bb926ecb02e4c533f2096666dfe Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Mon, 8 May 2023 22:05:00 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 547ce83..203c102 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -10,7 +10,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
-- 
cgit v1.2.3


From 6f2e3f7a64f6c57301e6df68c19ddfd542c77236 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Fri, 24 Mar 2023 19:13:53 +0100
Subject: d/control: Depend on tzdata-legacy

right/* timezones have been split into a separate tzdata-legacy package.
Since chronyd reads '/usr/share/zoneinfo/right/UTC' to determine when will the
next leap second occur we have to depend on this new package.
---
 debian/control | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/debian/control b/debian/control
index e5ceea2..41aa364 100644
--- a/debian/control
+++ b/debian/control
@@ -27,7 +27,7 @@ Architecture: linux-any
 Pre-Depends: ${misc:Pre-Depends}
 Depends: adduser,
          iproute2 [linux-any],
-         tzdata,
+         tzdata-legacy,
          ucf,
          ${misc:Depends},
          ${shlibs:Depends}
-- 
cgit v1.2.3


From 375d1c4c838c179a130c0cb153c4bf698f73b05f Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Mon, 27 Mar 2023 19:34:03 +0200
Subject: d/t/control: Let upstream-simulation-test-suite depend on
 tzdata-legacy

---
 debian/tests/control | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/debian/tests/control b/debian/tests/control
index 5586711..98b9106 100644
--- a/debian/tests/control
+++ b/debian/tests/control
@@ -1,5 +1,5 @@
 Tests: upstream-simulation-test-suite
-Depends: @builddeps@, build-essential, ca-certificates, wget
+Depends: @builddeps@, build-essential, ca-certificates, tzdata-legacy, wget
 Restrictions: isolation-container, build-needed, skippable, needs-root, needs-internet
 
 Tests: time-sources-from-dhcp-servers
-- 
cgit v1.2.3


From ff3fc7b0699b56323763498ad5dcbbe0c55e4578 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 21 Jun 2023 20:28:08 +0200
Subject: d/changelog: Update for the 4.3-4 release

---
 debian/changelog | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 8474242..a7284a7 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,16 @@
+chrony (4.3-4) unstable; urgency=medium
+
+  * debian/control:
+    - Depend on tzdata-legacy.
+    right/* timezones have been split into a separate tzdata-legacy package.
+    Since chronyd reads '/usr/share/zoneinfo/right/UTC' to determine when will
+    the next leap second occur we have to depend on this new package.
+
+  * debian/tests/control:
+    - Let upstream-simulation-test-suite depend on tzdata-legacy.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 21 Jun 2023 20:06:47 +0200
+
 chrony (4.3-2+deb12u1) unstable; urgency=medium
 
   * debian/usr.sbin.chronyd:
-- 
cgit v1.2.3


From 8cd1475a1f92baa98e945cdfe356fe92d622055d Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 21 Jun 2023 20:06:47 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 547ce83..203c102 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -10,7 +10,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
-- 
cgit v1.2.3


From f76b40d65991b55133937860b99584ce216b10c3 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 9 Aug 2023 17:50:42 +0200
Subject: Import chrony_4.4-1.debian.tar.xz

[dgit import tarball chrony 4.4-1 chrony_4.4-1.debian.tar.xz]
---
 .gitlab-ci.yml                                     |   11 +
 NEWS                                               |   70 +
 README.Debian                                      |   29 +
 changelog                                          | 2675 ++++++++++++++++++++
 chrony-dnssrv@.service                             |   17 +
 chrony-dnssrv@.timer                               |    9 +
 chrony-helper                                      |  264 ++
 chrony.conf                                        |   47 +
 chrony.default                                     |    6 +
 chrony.dhcp                                        |   27 +
 chrony.examples                                    |    1 +
 chrony.if-post-down                                |   11 +
 chrony.if-up                                       |   11 +
 chrony.keys                                        |   10 +
 chrony.lintian-overrides                           |    7 +
 chrony.maintscript                                 |    1 +
 chrony.ppp.ip-down                                 |   13 +
 chrony.ppp.ip-up                                   |   12 +
 chrony.service                                     |   65 +
 clean                                              |    1 +
 conf.d/README                                      |    7 +
 control                                            |   54 +
 copyright                                          |  187 ++
 dirs                                               |    6 +
 docs                                               |    3 +
 init                                               |   69 +
 install                                            |    9 +
 links                                              |    5 +
 ntp-units.d/50-chrony.list                         |    1 +
 .../debianize-chronyd-restricted-unit-file.patch   |   24 +
 ...nm-dispatcher-dhcp_Move-server_dir-to-run.patch |   19 +
 patches/series                                     |    2 +
 postinst                                           |   64 +
 postrm                                             |   56 +
 prerm                                              |   28 +
 rules                                              |   50 +
 source/format                                      |    1 +
 sources.d/README                                   |   12 +
 tests/control                                      |   28 +
 tests/dynamically-add-source                       |   27 +
 tests/fragmented-configuration                     |   17 +
 tests/helper-functions                             |   53 +
 tests/ntp-server-and-nts-auth                      |   59 +
 tests/time-sources-from-dhcp-servers               |   44 +
 tests/upstream-simulation-test-suite               |   41 +
 tests/upstream-system-tests                        |   24 +
 upstream/metadata                                  |    8 +
 upstream/signing-key.asc                           |   52 +
 usr.sbin.chronyd                                   |   85 +
 watch                                              |    3 +
 50 files changed, 4325 insertions(+)
 create mode 100644 .gitlab-ci.yml
 create mode 100644 NEWS
 create mode 100644 README.Debian
 create mode 100644 changelog
 create mode 100644 chrony-dnssrv@.service
 create mode 100644 chrony-dnssrv@.timer
 create mode 100755 chrony-helper
 create mode 100644 chrony.conf
 create mode 100644 chrony.default
 create mode 100644 chrony.dhcp
 create mode 100644 chrony.examples
 create mode 100644 chrony.if-post-down
 create mode 100644 chrony.if-up
 create mode 100644 chrony.keys
 create mode 100644 chrony.lintian-overrides
 create mode 100644 chrony.maintscript
 create mode 100644 chrony.ppp.ip-down
 create mode 100644 chrony.ppp.ip-up
 create mode 100644 chrony.service
 create mode 100644 clean
 create mode 100644 conf.d/README
 create mode 100644 control
 create mode 100644 copyright
 create mode 100644 dirs
 create mode 100644 docs
 create mode 100644 init
 create mode 100644 install
 create mode 100644 links
 create mode 100644 ntp-units.d/50-chrony.list
 create mode 100644 patches/debianize-chronyd-restricted-unit-file.patch
 create mode 100644 patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
 create mode 100644 patches/series
 create mode 100644 postinst
 create mode 100644 postrm
 create mode 100644 prerm
 create mode 100755 rules
 create mode 100644 source/format
 create mode 100644 sources.d/README
 create mode 100644 tests/control
 create mode 100644 tests/dynamically-add-source
 create mode 100644 tests/fragmented-configuration
 create mode 100644 tests/helper-functions
 create mode 100644 tests/ntp-server-and-nts-auth
 create mode 100644 tests/time-sources-from-dhcp-servers
 create mode 100644 tests/upstream-simulation-test-suite
 create mode 100755 tests/upstream-system-tests
 create mode 100644 upstream/metadata
 create mode 100644 upstream/signing-key.asc
 create mode 100644 usr.sbin.chronyd
 create mode 100644 watch

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000..68c9ac1
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,11 @@
+---
+include:
+    - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/salsa-ci.yml
+    - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/pipeline-jobs.yml
+
+variables:
+    # chrony now depends on tzdata-legacy which is only available in experimental
+    RELEASE: 'experimental'
+    # Skip the reprotest job as long as it is run as root due to problems with
+    # chrony system tests.
+    SALSA_CI_DISABLE_REPROTEST: 1
diff --git a/NEWS b/NEWS
new file mode 100644
index 0000000..fe7e4b9
--- /dev/null
+++ b/NEWS
@@ -0,0 +1,70 @@
+chrony (4.1~pre1-1) experimental; urgency=medium
+
+  Starting with chrony 4.0, it is possible to specify NTP sources in files
+  having the .sources suffix. In Debian, these files can be placed in
+  /etc/chrony/sources.d/ or any other directories specified by the 'sourcedir'
+  directive.
+  I would like to draw your attention that with chrony 4.1, each line of a
+  source file *must* be terminated by a trailing newline. Failing that, the NTP
+  source(s) will be ignored.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 25 Apr 2021 12:44:09 +0200
+
+chrony (3.4-2) unstable; urgency=medium
+
+  To reduce the range of operations available to chronyd, and thereby decrease
+  the kernel attack surface, a system call filter is now active by default
+  wherever¹ possible.
+  Please, take into account that this change prevents the use of the
+  “mailonchange” directive in chrony.conf as the chronyd process will not be
+  allowed to fork and execute the sendmail binary. Therefore, it is fundamental
+  to disable the system call filter to continue using this directive!
+
+  To do so, edit the /etc/default/chrony file and substitute the “-F -1”
+  parameter with “-F 0”. Restart chrony afterward.
+
+  ¹Are currently excluded alpha, ia64, m68k, riscv64, sh4 and sparc64
+   architectures due to lack of support in “libseccomp” and/or the Linux kernel.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 10 Feb 2019 18:44:22 +0100
+
+chrony (2.2.1-1) unstable; urgency=medium
+
+  In chrony versions before 2.2, the 'chrony.keys' file contained a command
+  key used for run-time configuration via the 'chronyc' command-line tool.
+  Starting from this version, support for this authentication method has been
+  dropped in favor of a Unix domain socket accessible only *locally* by root or
+  the _chrony system user. Consequently, if you refuse to use the 'chrony.keys'
+  file template provided by the maintainers when upgrading, please don’t forget
+  to manually remove the obsolete command key (ID 1) in the aforementioned file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 07 Feb 2016 17:02:30 +0100
+
+chrony (2.1.1-1) unstable; urgency=medium
+
+  From this version, 'chronyd' will strictly act as an NTP client by default. If
+  you want it to serve time to other systems, please do so by configuring the
+  'allow' directive.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 12 Oct 2015 19:12:39 +0200
+
+chrony (1.31.1-1) unstable; urgency=medium
+
+  From now on, we use the "hwclockfile" directive in /etc/chrony/chrony.conf.
+  Basically, it makes the detection of the standard (Local or UTC time) set
+  in /etc/adjtime — and used by the hardware clock — clearer compared to the
+  text processing method we used to use in the post install script to complete
+  the same task. Note that it overrides the "rtconutc" directive.
+
+  Also, we now create the _chrony system user to which chronyd will drop root
+  privileges. For users already allowing chronyd to drop root privileges in
+  favor of the user configured by the "user" directive in
+  /etc/chrony/chrony.conf, your configuration will remain unchanged and will
+  still work as intended.
+  However, some users might use a custom init script to accomplish the same
+  task by invoking chronyd with the '-u' option. We advise you to drop this
+  option from your init script before upgrading, otherwise you’ll have to
+  readjust the owner of the /var/l{ib,og}/chrony directories (recursively) to
+  the user you configured in your init script.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 6 Sep 2015 22:14:54 +0200
diff --git a/README.Debian b/README.Debian
new file mode 100644
index 0000000..2188ed9
--- /dev/null
+++ b/README.Debian
@@ -0,0 +1,29 @@
+Chrony for Debian
+-----------------
+
+ Notes about Debian-specific changes:
+
+ - Default chrony’s configuration files are located in the /etc/chrony directory.
+   It is filled by two important files:
+        → chrony.conf (configuration of the chronyd daemon, see man 5 chrony.conf
+          for further information)
+
+        → chrony.keys (lists keys used for NTP packets authentication, see
+          the “keyfile” directive in the chrony.conf(5) man page)
+
+ - We also provide /etc/ppp/ip-up.d/chrony and /etc/ppp/ip-down.d/chrony
+   to put chronyd online/offline depending on the PPP link status.
+
+ - Since version 1.31.1-1, we create the _chrony system user to which chronyd
+   will drop root privileges on initialisation. For users already allowing
+   chronyd to drop root privileges in favor of the user configured by the "user"
+   directive in chrony.conf, your configuration will remain unchanged and will
+   still work as it did. However, if you don’t want to deviate from Debian’s
+   default configuration, delete or comment out the "user" directive in
+   chrony.conf and recursively change the owner of the /var/lib/chrony and
+   /var/log/chrony directories. For example:
+
+        # sed -i 's/^user/#user/' /etc/chrony/chrony.conf
+        # chown -R _chrony:_chrony /var/l{ib,og}/chrony
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 01 Mar 2019 19:02:12 +0100
diff --git a/changelog b/changelog
new file mode 100644
index 0000000..a897316
--- /dev/null
+++ b/changelog
@@ -0,0 +1,2675 @@
+chrony (4.4-1) unstable; urgency=medium
+
+  * Import upstream version 4.4:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/:
+    - Update links to point to new chrony location.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/install:
+    - Install the chronyd-restricted systemd unit.
+
+  * debian/patches/:
+    - Add debianize-chronyd-restricted-unit-file.patch.
+
+  * debian/rules:
+    - Do not enable nor start chronyd-restricted.service.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 09 Aug 2023 17:50:42 +0200
+
+chrony (4.4~pre2-1) experimental; urgency=medium
+
+  * Import upstream version 4.4-pre2:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+    - Update clknetsim seed. This prevents the '148-replacement' test from
+    failing.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 21 Jun 2023 19:12:19 +0200
+
+chrony (4.4~pre1-1) experimental; urgency=medium
+
+  * Merge branch 'debian/unstable' into 'debian/latest'.
+
+  * Import upstream version 4.4-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 10 May 2023 16:26:48 +0200
+
+chrony (4.3-3) experimental; urgency=medium
+
+  * debian/control:
+    - Depend on tzdata-legacy. right/* timezones have been split into a
+    separate tzdata-legacy package. Since chronyd reads
+    '/usr/share/zoneinfo/right/UTC' to determine when will the next leap second
+    occur we have to depend on this new package. (LP: #2008076)
+
+  * debian/.gitlab-ci.yml:
+    - Run CI on experimental. This is necessary as long as tzdata-legacy is
+    available in experimental only.
+
+  * debian/tests/control:
+    - Let upstream-simulation-test-suite depend on tzdata-legacy.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 27 Mar 2023 19:57:20 +0200
+
+chrony (4.3-2+deb12u1) unstable; urgency=medium
+
+  * debian/usr.sbin.chronyd:
+    - Modify the AppArmor profile to allow more gpsd socket names. This will
+    avoid the need for users to override the profile to let chronyd consume PPS
+    samples or serial time supplied by gpsd over a Unix-domain socket.
+    Thanks to Ryan Govostes for the report. (Closes: #1034519)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 08 May 2023 22:05:00 +0200
+
+chrony (4.3-2) unstable; urgency=medium
+
+  * debian/control:
+    - Bump Standards-Version to 4.6.2 (no changes needed).
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/.gitlab-ci.yml:
+    - Use the recommended syntax to skip a job.
+
+  * debian/install:
+    - Install the chrony-wait.service systemd unit.
+
+  * debian/postinst:
+    - Ensure that chronyd can read the /etc/chrony/chrony.keys file after
+    dropping root privileges.
+
+  * debian/postrm:
+    - Remove the override for /etc/chrony/chrony.keys when purging chrony.
+
+  * debian/rules:
+    - Do not enable nor start chrony-wait.service for the time being.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Run each test only once. Running several iterations is no longer
+    relevant since we use a hard coded seed.
+
+  [ Taylor Stearns ]
+  * debian/chrony.conf:
+    - Replace U+2019 with ASCII quote. (MR: !10)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 27 Jan 2023 22:51:17 +0100
+
+chrony (4.3-1) unstable; urgency=medium
+
+  * Import upstream version 4.3:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  [ Bastian Blank ]
+  * debian/chrony.service:
+    - Let systemd handle directories. (MR: !9)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 31 Aug 2022 13:32:14 +0200
+
+chrony (4.3~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 4.3-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/chrony.lintian-overrides:
+    - Update lintian override syntax.
+
+  * debian/control:
+    - Bump Standards-Version to 4.6.1 (no changes needed).
+
+  * debian/patches/*:
+    - Drop ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch,
+    applied upstream.
+    - Refresh nm-dispatcher-dhcp_Move-server_dir-to-run.patch.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 11 Aug 2022 14:12:25 +0200
+
+chrony (4.2-2) unstable; urgency=medium
+
+  * debian/usr.sbin.chronyd:
+    - Allow reading the chronyd configuration file that timemaster(8)
+    generates. Thanks to Michael Lestinsky for the report! (Closes: #1004745)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 01 Feb 2022 20:42:35 +0100
+
+chrony (4.2-1) unstable; urgency=medium
+
+  * Import upstream version 4.2:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/chrony.service:
+    - Adopt upstream service unit hardening options.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/patches/*:
+    - Drop patches applied upstream.
+    - Add ensure_awk_commands_in_008-ntpera_test_return_an_integer.patch
+
+  * debian/test/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 13 Jan 2022 14:01:35 +0100
+
+chrony (4.1-4) unstable; urgency=medium
+
+  * debian/:
+    - Remove empty preinst maintainer script.
+
+  * debian/chrony.lintian-overrides:
+    - Remove unused overrides.
+
+  * debian/control:
+    - Bump Standards-Version to 4.6.0 (no changes needed).
+
+  * debian/patches/*:
+    - Add fix-seccomp-filter-for-BINDTODEVICE-socket-option.patch.
+    (Closes: #995207)
+
+  * debian/usr.sbin.chronyd:
+    - Add 'vim:syntax=apparmor' modline.
+    - Add feature ABI rule. Starting with AppArmor 3.0, policy needs to contain
+    an abi rule to indicate which feature abi the policy was developed under.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 07 Oct 2021 15:23:28 +0200
+
+chrony (4.1-3) unstable; urgency=medium
+
+  * Upload to unstable.
+
+  * debian/patches/:
+    - Add allow-clone3-and-pread64-in-seccomp-filter.patch.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 15 Aug 2021 15:08:56 +0200
+
+chrony (4.1-2) experimental; urgency=medium
+
+  * Merge branch 'debian/unstable' into 'debian/latest'.
+
+  * debian/rules:
+    - Remove needless dh_auto_test override.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/helper-functions:
+    - Improve chronyd restart logic. While rendering the tests more readable,
+    this also fixes ntp-server-and-nts-auth test on Ubuntu.
+
+  [ Debian Janitor ]
+  * debian/{control,chrony.maintscript}:
+    - Remove constraints unnecessary since stretch.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 26 Jun 2021 17:16:45 +0200
+
+chrony (4.1-1) experimental; urgency=medium
+
+  * Import upstream version 4.1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/upstream/signing-key.asc:
+    - Update Miroslav Lichvar's key.
+
+  * debian/watch:
+    - Add upstream version mangle to transform -pre to ~pre.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 14 May 2021 00:25:34 +0200
+
+chrony (4.1~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 4.1-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/control:
+    - Now that the upstream system tests support 'ss', replace the net-tools
+    build-dependency by iproute2.
+
+  * debian/NEWS:
+    - Mention that lines in *.sources files must be terminated by a trailing
+    newline.
+
+  * debian/patches/:
+    - Drop allow-IP_TOS-socket-option-in-seccomp-filter.patch. Applied
+    upstream.
+
+  * debian/postinst:
+    - Do not redirect 'chronyd -p' stderr to /dev/null. Not needed anymore.
+
+  * debian/sources.d/README:
+    - Mention that lines in *.sources files must be terminated by a trailing
+    newline.
+
+  * debian/tests/dynamically-add-source:
+    - Terminate the line in dummy-server.sources with the newline control
+    character.
+
+  * debian/tests/fragmented-configuration:
+    - Do not redirect 'chronyd -p' stderr to /dev/null. Not needed anymore.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 10 May 2021 18:56:53 +0200
+
+chrony (4.0-8) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-BINDTODEVICE-option-in-seccomp-filter.patch to enable support
+    for binding sockets to a device without having to disable the seccomp
+    filter.
+    - Add allow-getuid32-in-seccomp-filter.patch. Upstream found out that
+    getuid32() needed to be allowed in the seccomp filter to enable some NTS
+    operations on i686. This may affect other 32-bits architectures.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 13 May 2021 16:51:41 +0200
+
+chrony (4.0-7) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-IP_TOS-socket-option-in-seccomp-filter.patch to enable the use
+    of the 'dscp' directive.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 08 Apr 2021 16:21:16 +0200
+
+chrony (4.0-6) unstable; urgency=medium
+
+  * debian/tests/helper-functions:
+    - Instead of running 'systemctl restart chrony.service', use
+    __restart_chronyd() in the __no_system_clock_control() function.
+    - Run 'sleep 3' only if chronyd has successfully restarted.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/{dynamically-add-source,ntp-server-and-nts-auth}:
+    - Reduce default Ubuntu config to make space for testcase config.
+
+  * debian/tests/helper-functions:
+    - Add more common functions and update some tests to use them.
+    - Wait after restarting chronyd. Without this, some tests break on Ubuntu by
+    checking state too early.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 21 Feb 2021 21:59:22 +0100
+
+chrony (4.0-5) unstable; urgency=medium
+
+  * Follow DEP-14 branch naming conventions:
+    master -> debian/latest
+    upstream -> upstream/latest
+
+  * debian/chrony.service:
+    - Enable some hardening settings.
+
+  * debian/control:
+    - Remove Joachim Wiedorn from the Uploaders field. This decision was taken
+    in agreement with him. Thanks a lot, Joachim, for your work on chrony and
+    for your benevolence when you handed me its maintenance.
+    - Point Vcs-Git to the debian/latest branch.
+
+  * debian/dirs:
+    - Do not create the /etc/apparmor.d/force-complain directory. Not needed
+    anymore.
+
+  * debian/postrm:
+    - Remove /run/chrony-dhcp on purge.
+
+  * debian/preinst:
+    - Drop old migration code snippet. It was used to put the newly provided
+    AppArmor profile in complain mode when upgrading chrony to prevent
+    regressions this profile could have caused. (Closes: #905485)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 04 Feb 2021 19:49:22 +0100
+
+chrony (4.0-4) unstable; urgency=medium
+
+  * debian/chrony.examples:
+    - Provide example configuration files.
+
+  * debian/postinst:
+    - Run adduser unconditionally.
+    - Use 'chronyd -p' to check the whole configuration.
+
+  * debian/tests/:
+    - Prevent dynamically-add-source and ntp-server-and-nts-auth tests from
+    failing on chronyd's preparation step.
+    - Don't pass 'set -u' to dynamically-add-source and
+    ntp-server-and-nts-auth scripts.
+
+  * debian/tests/control:
+    - Mark dynamically-add-source as skippable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 21 Jan 2021 20:02:39 +0100
+
+chrony (4.0-3) unstable; urgency=medium
+
+  * debian/:
+    - chronyd's configuration can now be fragmented. Please see
+    /etc/chrony/conf.d/README for more information.
+    - NTP sources can be specified in /etc/chrony/sources.d. Please see
+    /etc/chrony/sources.d/README for more information.
+
+  * debian/chrony.conf:
+    - Include configuration files found in /etc/chrony/conf.d.
+    - Use NTP sources found in /etc/chrony/sources.d.
+    - Get TAI-UTC offset and leap seconds from the system tz database by using
+    the "leapsectz right/UTC" directive. This directive must be commented out
+    when using time sources serving leap-smeared time. (Closes: #974845)
+    - Add missing comment.
+
+  * debian/chrony.default:
+    - Switch the seccomp filter to level 1.
+
+  * debian/chrony.lintian-overrides:
+    - Override breakout-link.
+
+  * debian/control:
+    - Add tzdata to the dependencies.
+    - Bump Standards-Version to 4.5.1 (no changes required).
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/postinst:
+    - Use dpkg-statoverride to manage mode bits and ownership of
+    /var/l{ib,og}/chrony.
+
+  * debian/postrm:
+    - Remove overrides for /var/l{ib,og}/chrony on purge.
+
+  * debian/rules:
+    - Drop '--without-readline' option. GNU readline support has been dropped
+    upstream due to license incompatibility.
+    - Replace -F -1 by -F 1 in the sed invocation.
+
+  * debian/tests/:
+    - Add fragmented-configuration autopkgtest.
+    - Add dynamically-add-source autopkgtest.
+    - Add ntp-server-and-nts-auth autopkgtest.
+
+  * debian/tests/control:
+    - Mark ntp-server-and-nts-auth as skippable.
+
+  * debian/tests/fragmented-configuration:
+    - Use another directive for the test since "leapsectz right/UTC" is now
+    used by default.
+
+  * debian/tests/helper-functions:
+    - Add __no_system_clock_control() function.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Always use the same seed to get deterministic results.
+
+  * debian/upstream/metadata:
+    - Remove obsolete field Name. Thanks to Debian Janitor <janitor@jelmer.uk>.
+
+  * debian/usr.sbin.chronyd:
+    - Make use of the @{run} variable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 18 Jan 2021 21:58:52 +0100
+
+chrony (4.0-2) unstable; urgency=medium
+
+  * Merge branch 'experimental' into 'master'.
+
+  * Upload to unstable.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 13 Oct 2020 15:59:33 +0200
+
+chrony (4.0-1) experimental; urgency=medium
+
+  * Import upstream version 4.0:
+    - This release adds support for the Network Time Security (NTS)
+    authentication mechanism (RFC 8915).
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 07 Oct 2020 19:14:51 +0200
+
+chrony (4.0~pre4-2) experimental; urgency=medium
+
+  * debian/postinst:
+    - Fix user and group ownership of "/var/lib/chrony" to allow chronyd
+    to write in it. This will also fix a regression in the 104-systemdirs
+    test.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 03 Oct 2020 11:20:02 +0200
+
+chrony (4.0~pre4-1) experimental; urgency=medium
+
+  * Import upstream version 4.0-pre4:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * Merge branch 'master' into experimental. (Closes: #970421)
+
+  * debian/chrony.conf:
+    - Use NTP sources from /run/chrony-dhcp.
+    - Save NTS keys and cookies in /var/lib/chrony/.
+
+  * debian/chrony-dnssrv@.service:
+    - Update "chrony-helper" path.
+
+  * debian/chrony.dhcp:
+    - Save NTP servers from DHCP to /run/chrony-dhcp/$interface.sources.
+
+  * debian/chrony.lintian-overrides:
+    - Override executable-in-usr-lib for NetworkManager dispatcher scripts.
+    - Update NetworkManager dispatcher script name.
+
+  * debian/chrony.ppp.ip-{down,up}:
+    - Update PID file path.
+
+  * debian/chrony.service:
+    - Update PID file path.
+    - Do not run 'chrony-helper update-daemon' after starting chronyd. Not
+    needed anymore.
+
+  * debian/control:
+    - Build-depend on libgnutls28-dev to support NTS.
+    - Build-depend on gnutls-bin for the test suite.
+    - Bump debhelper-compat to 13.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/dirs:
+    - Remove var/log/chrony as it will be created automatically if it doesn’t
+    exist.
+
+  * debian/if-{post-down,up}:
+    - Update PID file path.
+
+  * debian/init:
+    - Update PID file path.
+    - Drop the unnecessary '--remove pidfile' option from the stop target.
+    - Do not run 'chrony-helper update-daemon' after starting chronyd. Not
+    needed anymore.
+
+  * debian/install:
+    - Move "chrony-helper" to "/usr/libexec/chrony".
+
+  * debian/links:
+    - Update source and destination filenames.
+
+  * debian/patches/:
+    - Drop patches applied upstream.
+    - Add nm-dispatcher-dhcp_Move-server_dir-to-run.patch.
+
+  * debian/postinst:
+    - Drop migration code from pre-Stretch.
+    - Migrate NTP sources obtained from DHCP to /run/chrony-dhcp on upgrade
+    from chrony < 4.0~pre4-1.
+    - Remove staled PID file when upgrading from chrony < 4.0~pre4-1.
+
+  * debian/rules:
+    - Change the default PID file location from /run to /run/chrony.
+    - Drop dh_missing --fail-missing. This is the default in debhelper 13.
+    - Enable seccomp support by default on riscv64.
+    - Update NetworkManager dispatcher script name from 20-chrony to
+    20-chrony-onoffline.
+    - Add DHCP NetworkManager dispatcher script to allow chronyd to use
+    NTP sources obtained from NM's internal DHCP client.
+
+  * debian/tests/:
+    - Add some helper functions. Some tests will be updated thereafter
+    to use them.
+
+  * debian/tests/time-sources-from-dhcp-servers:
+    - Adapt to the new way of using time sources from DHCP.
+    - Improve sed invocation.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version.
+    - Cosmetic changes.
+
+  * debian/tests/upstream-system-tests:
+    - No need to stop systemd-timesyncd anymore since it is no more
+    co-installable with chrony anymore.
+
+  * debian/usr.sbin.chronyd:
+    - Update PID file path.
+    - Add dac_override and dac_read_search capabilities to give "root" the
+    ability to write the PID file in /run/chrony/.
+    - Prefix flag definition by "flags=".
+    - Sort the capabilities.
+    - Grant CAP_NET_RAW capability to allow an NTP socket to be bound to a
+    device using the SO_BINDTODEVICE socket option on kernels before 5.7.
+    - Add comments regarding capabilities.
+    - Let chronyd create /var/l{ib,og}/chrony.
+    - Remove a superfluous rule.
+    - Allow reading of NTP sources in /run/chrony-dhcp/.
+
+  * debian/watch:
+    - Make use of special strings.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 02 Oct 2020 21:21:08 +0200
+
+chrony (3.5.1-1) unstable; urgency=medium
+
+  * Import upstream version 3.5.1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+    - CVE-2020-14367: create new file when writing pidfile.
+
+  * debian/chrony.lintian-overrides:
+    - Remove unused override.
+
+  [ Ville Skyttä ]
+  * debian/chrony.conf:
+    - Comment spelling fix. (MR: !5)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 20 Aug 2020 14:07:22 +0200
+
+chrony (3.5-9) unstable; urgency=medium
+
+  * debian/patches/:
+    - Add allow-some-*time64-syscalls-in-seccomp-filter.patch. Needed for
+    32-bit architectures with new system calls using 64-bit time_t.
+    (LP: #1878005)
+
+  * debian/tests/control:
+    - Add needs-internet restriction to the upstream-simulation-test-suite
+    test.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-simulation-test-suite:
+    - Skip if preparation steps fail.
+    - Make preparation steps more verbose.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 19 May 2020 16:42:18 +0200
+
+chrony (3.5-8) unstable; urgency=medium
+
+  * debian/postrm:
+    - Stop starting systemd-timesyncd in postrm. This is no longer relevant
+    since systemd-timesyncd is a standalone package declaring
+    Conflicts/Replaces/Provides: time-daemon. (Closes: #955773)
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-system-tests:
+    - Stop chrony/systemd-timesynd before running these tests. (LP: #1870144)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 05 Apr 2020 17:44:31 +0200
+
+chrony (3.5-7) unstable; urgency=medium
+
+  * debian/chrony.maintscript:
+    - Remove the /etc/NetworkManager/dispatcher.d/20-chrony conffile.
+
+  * debian/control:
+    - Support seccomp facility on riscv64. It should be noted that the system
+    call filter will stay disabled by default on this architecture until
+    Linux >= 5.5 hits unstable.
+    - Bump libseccomp-dev build-dep to 2.4.3-1~ to provide seccomp facility on
+    riscv64.
+    - Break network-manager (<< 1.20.0-1~). Prior to this version,
+    NetworkManager would not look for dispatcher scripts into
+    /usr/lib/NetworkManager/dispatcher.d/.
+
+  * debian/dirs:
+    - Create the usr/lib/NetworkManager/dispatcher.d subdirectories.
+
+  * debian/links:
+    - Change the location of the NetworkManager dispatcher script.
+
+  * debian/patches/:
+    - Add allow-renameat2-in-seccomp-filter.patch. Required as the riscv64
+    architecture does not support the rename() and renameat() system calls.
+
+  * debian/rules:
+    - Move the NetworkManager dispatcher script in
+     /usr/lib/NetworkManager/dispatcher.d/.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 17 Mar 2020 15:21:53 +0100
+
+chrony (3.5-6) unstable; urgency=medium
+
+  * debian/chrony.service:
+    - Don’t conflict with systemd-timesyncd.service.
+    A few users complain that chronyd does not start at boot. The way the
+    Conflict= directive works internally might cause both systemd-timesyncd
+    and chronyd to be inactive at boot. So by relying solely on the
+    disable-with-time-daemon.conf drop-in file provided by systemd, we should
+    get rid of this malfunction while still preventing these two time daemons
+    from being active at the same time. Kudos notably go to Santiago Vila for
+    the report and providing SSH access to a GCE instance where the issue was
+    reproducible and Michael Biebl for debugging. (Closes: #947936)
+
+  * debian/control:
+    - Bump Standards-Version to 4.5.0 (no changes required).
+    - No need to explicitly conflict with ntp as it now provides time-daemon.
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/patches/:
+    - Add allow-clock_adjtime-in-seccomp-filter.patch.
+    glibc 2.31 switched the adjtimex() function to the clock_adjtime
+    system call.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Update clknetsim version. This new version supports glibc >= 2.31 headers.
+    (LP: #1866753)
+
+  * debian/tests/control:
+    - Run the upstream-simulation-test-suite as root.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 10 Mar 2020 19:17:16 +0100
+
+chrony (3.5-5) unstable; urgency=medium
+
+  * debian/control:
+    - Bump standard-version to 4.4.1 (no change required).
+
+  * debian/install:
+    - Install 50-chrony.list in /usr/lib/systemd/ntp-units.d.
+
+  * debian/ntp-units.d/50-chrony.list:
+    - Allow timedated to interact with chronyd.
+
+  * debian/patches/*:
+    - Cherry-pick upstream commits to better manage RTCs that don't support
+    interrupts. This fixes an issue exhibited when a specific upstream system
+    test is run on the Ubuntu CI. Thank to Christian Ehrhardt for working
+    with Miroslav Lichvar to address this problem.
+
+  * debian/tests/control:
+    - Use @builddeps@ as a test dependency for upstream_system_tests.
+
+  [ Christian Ehrhardt ]
+  * debian/tests/upstream-simulation-test-suite:
+    - Redirect stderr on make call to stdout. On some architectures (e.g. armhf)
+    the clksim tests compile but throw some warnings. (MR: !2)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 22 Dec 2019 17:30:40 +0100
+
+chrony (3.5-4) unstable; urgency=medium
+
+  * debian/tests/control:
+    - Add @builddeps@ to the list of dependencies needed by the
+    upstream-simulation-test-suite test.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 30 Aug 2019 00:49:20 +0200
+
+chrony (3.5-3) unstable; urgency=medium
+
+  * debian/chrony.lintian-overrides:
+    - Override package-supports-alternative-init-but-no-init.d-script. This
+    is a false positive. chrony-dnssrv@.service isn’t a daemon but a oneshot
+    service, not started at boot, whose role is to lookup for _ntp._udp DNS SRV
+    records.
+
+  * debian/chrony.service:
+    - Pull in time-sync.target and order chrony before it as recommended in
+    systemd.special(7).
+
+  * debian/control:
+    - Bump standard-version to 4.4.0 (no changes required).
+
+  * debian/.gitlab-ci.yml:
+    - Switch to standard Salsa Pipeline.
+    - Skip the reprotest job for as long as it is run as root due to problems
+    with chrony system tests.
+
+  * debian/tests/*:
+    - Revamp the upstream-simulation-test-suite test.
+    - Adjust dpkg dependencies for upstream-simulation-test-suite.
+    - Adjust restrictions for upstream-simulation-test-suite.
+    - Introduce upstream-system-tests. Add a new set of tests for testing
+    basic chronyd functionality. Destructive tests are run in a virtual
+    machine.
+    - Add ethtool to the list of dependencies needed by
+    run_destructive_system_tests.
+    - exit 77 if upstream-simulation-test-suite is run on non-Linux and mark
+    the test as skippable. Thanks to Paul Gevers <elbrus@debian.org> for the
+    suggestion.
+    - Make artifacts() exit 1. Again, thanks to Paul Gevers.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 13 Aug 2019 17:57:47 +0200
+
+chrony (3.5-2) unstable; urgency=medium
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/chrony.dhcp:
+    - Fix shellcheck warnings. Patch imported from Fedora.
+
+  * debian/chrony-helper:
+    - Fix shellcheck warnings. Patch imported from Fedora.
+
+  * debian/clean:
+    - Drop obsolete entries.
+
+  * debian/copyright:
+    - Update copyright years.
+    - Update copyright holder for the configure script.
+
+  * debian/patches/*:
+    - Add update_processing_of_packet_log.patch. This fixes a regression in
+    the simulation tests exhibited by the recent clknetsim changes.
+    (Closes: #931181)
+
+  * debian/rules:
+    - Use dh_missing --fail-missing.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Use a known good clknetsim commit. This should prevent regressions from
+    on-going “clknetsim” development.
+
+  * debian/usr.sbin.chronyd:
+    - Grant access rights only to the ntp_signd socket. (Closes: #928170)
+
+  [ Christian Ehrhardt ]
+  * debian/postrm:
+    - Re-establish systemd-timesyncd on removal. (MR: !1)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 06 Jul 2019 20:33:41 +0200
+
+chrony (3.5-1) experimental; urgency=medium
+
+  * Import upstream version 3.5:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/control:
+    - Ignore net-tools and procps build-dependencies if the profile nocheck is
+    active.
+
+  * debian/rules:
+    - No test suite should be run if nocheck is passed to DEB_BUILD_OPTIONS.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 15 May 2019 18:44:12 +0200
+
+chrony (3.5~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.5-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/.gitlab-ci.yml:
+    - Use .build-package template job instead of .build-unstable. The latter
+    is deprecated.
+
+  * debian/chrony.keys:
+    - Fix the comment about the location of the list of supported hash
+    functions and output encoding. These information are now available by
+    consulting the “keyfile” directive in the chrony.conf(5) man page.
+
+  * debian/control:
+    - Drop dependency on lsb-base. Is is required when booting with sysvinit
+    and initscripts, however initscripts already Depends on lsb-base.
+    - Build-depend on net-tools and procps. kill, netstat and ps are needed
+    for the new system tests executed at build time (iff building as root).
+
+  * debian/copyright:
+    - Add an entry for test/system/* files.
+
+  * debian/patches/*:
+    - Drop all patches, they have been applied upstream.
+
+  * debian/postinst:
+    - Drop migration code from pre-stretch.
+
+  * debian/README.Debian:
+    - Fix information related to the chrony.keys file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 12 May 2019 22:16:14 +0200
+
+chrony (3.4-4) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Add allow-further-syscalls-in-seccomp-filter.patch. Supplementing the
+    seccomp filter whitelist with those syscalls is a prerequisite, notably for
+    the arm64 architecture.
+
+  [ Leigh Brown ]
+  * debian/patches/*:
+    - Add allow-recv-send-in-seccomp-filter.patch. Necessary on armel and
+    ppc64el. Other architectures might also be affected. (Closes: #924494)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 18 Mar 2019 19:35:34 +0100
+
+chrony (3.4-3) unstable; urgency=medium
+
+  * debian/.gitlab-ci.yml:
+    - Check for missing hardening flags.
+
+  * debian/patches/*:
+    - Add allow-_llseek-in-seccomp-filter.patch. Needed on various 32-bit
+    plateforms to log the {raw}measurements and statistics information when
+    the seccomp filter is enabled. Thanks a lot to Francesco Poli (wintermute)
+    <invernomuto@paranoici.org> for the report. (Closes: #923137)
+    - Add allow-waitpid-in-seccomp-filter.patch. Needed to correctly stop
+    chronyd on some plateforms when the seccomp filter is enabled.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 04 Mar 2019 23:32:12 +0100
+
+chrony (3.4-2) unstable; urgency=medium
+
+  * debian/.gitlab-ci.yml:
+    - Replace home-made GitLab CI with the standard Salsa pipeline.
+    - Allow autopkgtest job to fail. The time-sources-from-dhcp-servers test
+    currently fails due to a testbed issue on salsa CI.
+
+  * debian/chrony.default:
+    - Enable the system call filter by default.
+
+  * debian/control:
+    - Bump standard-version to 4.3.0 (no changes required).
+    - Use the new debhelper-compat (= 12) notation and drop d/compat.
+    - Add Pre-Depends: ${misc:Pre-Depends}. Debhelper compatibility level 12
+    makes use of the “--skip-systemd-native” flag from “invoke-rc.d”. Adding
+    Pre-Depends: ${misc:Pre-Depends} to d/control ensure that we have a recent
+    enough version of “init-system-helpers”.
+    - Suggest networkd-dispatcher.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2019.
+
+  * debian/links:
+    - Now that “networkd-dispatcher” is in the Debian archive, link
+    NetworkManager dispatcher script to networkd-dispatcher routable and off
+    states. Patch cherry-picked from Ubuntu; thanks to Christian Ehrhardt
+    <christian.ehrhardt@canonical.com> for working on this.
+
+  * debian/NEWS:
+    - Report that a system call filter is now enabled by default and the way
+    to disable it if needed.
+
+  * debian/rules:
+    - Don’t enable the system call filter on some architectures due to missing
+    support in the “libseccomp” and/or the Linux kernel.
+
+  * debian/upstream/:
+    - Strip upstream key from extra signatures. Thanks lintian!
+    - Remove the Miroslav-Lichvar.txt file as it serves no purpose.
+
+  * debian/usr.sbin.chronyd:
+    - Don’t include “tunables/sys”. The etc/apparmor.d/tunables/sys file has
+    been deprecated in AppArmor 2.13.1! The @{sys} variable is now defined in
+    “tunables/kernelvars” which is included in “tunables/global”.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 13 Feb 2019 17:08:17 +0100
+
+chrony (3.4-1) unstable; urgency=medium
+
+  * Import upstream version 3.4:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/chrony.service:
+    - Conflict with ntpsec.service.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/patches/*:
+    - Remove fix-samplefilt-unit-test-to-work-with-low-precision-clock.patch,
+    fixed upstream.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 21 Sep 2018 14:12:03 +0200
+
+chrony (3.4~pre1-2) experimental; urgency=medium
+
+  * debian/patches/*:
+    - Cherry-pick upstream patch to fix samplefilt unit test to work with
+    low-precision clocks. This should prevent chrony from failing to build
+    from source on HPPA and Alpha.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 10 Sep 2018 18:39:58 +0200
+
+chrony (3.4~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.4-pre1:
+    - Please see /usr/share/doc/chrony/NEWS.gz for the release notes.
+
+  * debian/:
+    - Add “.gitlab-ci.yml” file to use GitLab Continuous Integration.
+
+  * debian/chrony.if-{post-down,up}:
+    - Use the new “onoffline” command to tell chronyd to switch all sources to
+    the online or offline status according to the current network configuration.
+
+  * debian/chrony.ppp.ip-{down,up}:
+    - As for ifupdown scripts, use the “onoffline” command.
+
+  * debian/control:
+    - Bump standard-version to 4.2.1 (no changes required).
+
+  * debian/patches/*:
+    - Remove fall-back-to-urandom.patch. Applied in this prerelease.
+
+  * debian/post{inst,rm}:
+    - Use “command -v” instead of “which” to enhance portability.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 02 Sep 2018 19:14:08 +0200
+
+chrony (3.3-3) unstable; urgency=medium
+
+  * debian/:
+    - Normalize packaging with “wrap-and-sort -ab”.
+
+  * debian/control:
+    - Bump standard-version to 4.2.0:
+        ↳ Install upstream release notes as “/usr/share/doc/chrony/NEWS.gz”.
+          Installing these as “/usr/share/doc/package/changelog.gz” is now
+          deprecated.
+
+  * debian/patches/:
+    - Cherry-pick upstream patch to avoid hangs when starting
+    chronyd on newer kernels by falling back to urandom.
+    Thanks to Gustavo Scalet <gustavo.scalet@collabora.com> for the report and
+    the initial patch. (LP: #1787366, Closes: #906276)
+
+  * debian/upstream/metadata:
+    - Add DEP12 upstream metadata file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 18 Aug 2018 16:23:19 +0200
+
+chrony (3.3-2) unstable; urgency=medium
+
+  * debian/chrony.service:
+    - Conflict with ntp.service.
+
+  * debian/control:
+    - Bump standard-version to 4.1.4 (no changes required).
+    - Switch to the Nettle cryptographic library for hash functions.
+
+  [ Helmut Grohne ]
+  * debian/rules:
+    - Pass CC to make and set “--host-system” to fix FTCBFS. (Closes: #895852)
+
+  [ Christian Ehrhardt ]
+  * debian/usr.sbin.chronyd:
+    - Support all paths suggested in the man page.
+    (LP: #1771028, Closes: #898614)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 14 May 2018 21:37:30 +0200
+
+chrony (3.3-1) unstable; urgency=medium
+
+  * Import upstream version 3.3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * Merge branch “experimental” into “master”.
+
+  * debian/copyright:
+    - Update copyright year.
+
+  * debian/usr.sbin.chronyd:
+    - Allow CAP_NET_ADMIN to support HW timestamping. (LP: #1761327)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 05 Apr 2018 02:08:31 +0200
+
+chrony (3.3~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.3-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/copyright:
+    - Add “hash_nettle.c” copyright information and update copyright year of
+    test/unit/*
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 15 Mar 2018 13:58:21 +0100
+
+chrony (3.2-5) unstable; urgency=medium
+
+  [ Christian Ehrhardt ]
+  * debian/usr.sbin.chronyd:
+    - Allow write access to RTC, PPS and PTP devices.
+    (Closes: #891201, LP: #1751241)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 28 Feb 2018 17:31:08 +0100
+
+chrony (3.2-4) unstable; urgency=medium
+
+  * debian/changelog:
+    - Remove trailing spaces.
+
+  * debian/chrony-dnssrv@.service:
+    - Use NTP servers obtained from DNS SRV records.
+
+  * debian/chrony-dnssrv@.timer:
+    - Periodic lookup of DNS SRV records.
+
+  * debian/chrony-helper:
+    - New helper script to make use of NTP servers obtained from DHCP and
+    _ntp._udp DNS SRV records.
+
+  * debian/chrony.dhcp:
+    - Add a dhclient-exit-hook script to add/remove NTP servers depending
+    on the operations invoked by the DHCP client. (Closes: #889656)
+
+  * debian/chrony.service:
+    - Run “/usr/lib/chrony/chrony-helper update-daemon” after starting chronyd.
+
+  * debian/control:
+    - Suggest dnsutils. The dig utility is used to update files with NTP
+    servers from DNS SRV records.
+
+  * debian/init:
+    - Run “/usr/lib/chrony/chrony-helper update-daemon” after starting chronyd.
+
+  * debian/install:
+    - Install the chrony-helper script in /usr/lib/chrony.
+    - Install chrony-dnssrv@.* files in /lib/systemd/system.
+
+  * debian/postinst:
+    - Don’t use recursive chown as this is vulnerable to hardlink attacks on
+    mainline, non-Debian kernels that do not have fs.protected_hardlinks=1.
+    Thanks Lintian!
+
+  * debian/postrm:
+    - Remove “/run/chrony” on purge.
+
+  * debian/rules:
+    - Install the dhclient-exit-hook script in /etc/dhcp/dhclient-enter-hooks.
+
+  * debian/tests/:
+    - Use autopkgtest to ensure that chronyd can use NTP servers obtained from
+    DHCP servers.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 20 Feb 2018 18:27:10 +0100
+
+chrony (3.2-3) unstable; urgency=medium
+
+  [ Christian Ehrhardt ]
+  * debian/chrony.default:
+    - Mention systemd service file in the comment.
+
+  * debian/chrony.service:
+    - Support the DAEMON_OPTS variable from “/etc/default/chrony” in systemd
+    environment. (LP: #1746081, Closes: #889012)
+
+  * debian/usr.sbin.chronyd:
+    - Allow the creation of /run/chrony on demand.
+    (LP: #1746444, Closes: #889011)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 07 Feb 2018 21:27:09 +0100
+
+chrony (3.2-2) unstable; urgency=medium
+
+  * Initial AppArmor profile for chronyd. Thanks to Jamie
+    Strandboge <jamie@ubuntu.com>. (Closes: #888038)
+
+  * debian/compat:
+    - Bump to debhelper compat 11.
+
+  * debian/control:
+    - Bump standard-version to 4.1.3 (no changes required).
+    - Build depend on debhelper ≥ 11.
+    - Set “Rules-Requires-Root: no”.
+    - Move Vcs-* to salsa.debian.org.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2018.
+
+  * debian/postinst:
+    - Don’t force removal of cron file since it doesn’t exist anymore.
+
+  * debian/preinst:
+    - Update the chrony version on which to act.
+    - Add the debhelper token.
+
+  * debian/usr.sbin.chronyd:
+    - Improve AppArmor profile to support more chronyd features and ease
+    portability with other distros.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 28 Jan 2018 19:33:46 +0100
+
+chrony (3.2-1) unstable; urgency=medium
+
+  * Import upstream version 3.2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 15 Sep 2017 11:37:10 +0200
+
+chrony (3.2~pre2-1) experimental; urgency=medium
+
+  * Import upstream version 3.2-pre2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/control:
+    - Bump standard-version to 4.1.0 (no changes required).
+
+  * debian/copyright:
+    - Update copyright years.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 30 Aug 2017 15:48:37 +0200
+
+chrony (3.2~pre1-1) experimental; urgency=medium
+
+  * Import upstream version 3.2-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/patches/*:
+    - Remove allow_getpid_in_seccomp_filter.patch and update the series file
+    accordingly.
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Run tests in multiple iterations.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 25 Jul 2017 21:13:22 +0200
+
+chrony (3.1-5) unstable; urgency=medium
+
+  * debian/chrony.if-up:
+    - Do not pass the “burst” command to chronyc as the script could return an
+    error in certain situations. As a consequence, that would prevent ifupdown
+    from writing the current state of the interfaces in /run/network/ifstate.
+    Thanks to John Eikenberry <jae@zhar.net> for reporting that issue.
+    (Closes: #868491)
+
+  * debian/chrony.ppp.ip-up:
+    - Take the same action as for the “chrony.if-up” script as a precautionary
+    measure.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 17 Jul 2017 16:47:56 +0200
+
+chrony (3.1-4) unstable; urgency=medium
+
+  * Now that Stretch has been released (\o/), let’s upload chrony 3.1 to
+    unstable.
+
+  * debian/:
+    - Remove the menu file used to launch “chronyc”. It is a CLI only tool,
+    thus it probably does not make a lot of sense to keep it in the Debian
+    menu.
+
+  * debian/control:
+    - Drop dependency on pre-jessie util-linux version.
+    - Bump standard-version to 4.0.0 (no changes required).
+
+  * debian/tests/upstream-simulation-test-suite:
+    - Fix the leading comment which mentioned “vm” despite the fact that the
+    test runs in a container.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 19 Jun 2017 02:30:10 +0200
+
+chrony (3.1-3) experimental; urgency=medium
+
+  * debian/chrony.if-{post-down,up}:
+    - Remove unnecessary “else” statements.
+
+  * debian/chrony.ppp.ip-down:
+    - Don’t check and delete “/var/run/chrony-ppp-up”, that file doesn’t exist
+    anymore.
+    - Check for pid file existence instead of calling “pidof”.
+
+  * debian/chrony.ppp.ip-up:
+    - Don’t create “/var/run/chrony-ppp-up” file after the ppp link came up.
+    - Check for pid file existence instead of calling “pidof”.
+    - Don’t call “chronyc” using its absolute path.
+    - Check for the presence of a default route before advising “chronyd” that
+    the network connectivity to the sources is ready.
+
+  * debian/init:
+    - Check if “$PIDFILE” exists before taking action.
+    - Do not print informational messages.
+    - Remove the “chronyd” pid file when stopping as it doesn’t do it on
+    its own.
+    - Rework the “restart|force-reload” pattern.
+    - Make use of some init-functions.
+    - Print a message if “chronyd” is already running while attempting to start
+    it.
+    - Do not delete “/var/run/chrony-ppp-up”, that file doesn’t exist anymore.
+
+  * d/rules:
+    - Move the default pid file from “/var/run” to “/run”.
+
+  * d/tests/*:
+    - Use autopkgtest facility to run the upstream simulation test suite.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 14 May 2017 17:26:15 +0200
+
+chrony (3.1-2) experimental; urgency=medium
+
+  * Merge branch 'master' into experimental. (Closes: #861258)
+
+  * debian/patches/*:
+    - Remove the “fix_time_smoothing_in_interleaved_mode.patch” patch. Not
+    needed anymore.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 26 Apr 2017 21:17:43 +0200
+
+chrony (3.1-1) experimental; urgency=medium
+
+  * Import upstream version 3.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.conf:
+    - Remove the “hwclockfile” directive. Unneeded now that the configure
+    script allows us to set the default path to the adjtime file via the
+    “--with-hwclockfile” option.
+
+  * debian/copyright:
+    - Update copyright years.
+
+  * debian/rules:
+    - Specify default path to hwclock adjtime file.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 02 Feb 2017 19:24:30 +0100
+
+chrony (3.0-4) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Backport commit 768bce799bfe to make chrony operable with the syscall
+    filtering feature enabled in level 1. (Closes: #861258)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 26 Apr 2017 17:39:44 +0200
+
+chrony (3.0-3) unstable; urgency=medium
+
+  * debian/patches/*:
+    - Backport an upstream patch to fix time smoothing in interleaved mode.
+    (Closes: #854424)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 07 Feb 2017 00:37:24 +0100
+
+chrony (3.0-2) unstable; urgency=medium
+
+  * debian/chrony.conf:
+    - Disable logging by default, it waste some disk space and users are
+    probably better served by “chronyc sources” and “chronyc sourcestats”
+    commands anyway.
+
+  * debian/chrony.service:
+    - Remove the “Restart=on-failure” option. There are possible security
+    implications for NTP clients.
+
+  * debian/dirs:
+    - Add etc/logrotate.d to avoid build failure.
+
+  * Remove our logrotate configuration file in favour of the upstream’s one.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 Jan 2017 15:26:31 +0100
+
+chrony (3.0-1) unstable; urgency=medium
+
+  * Import upstream version 3.0:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * Merge branch “experimental”:
+    - Enable support for MS-SNTP authentication in Samba.
+    - Rename --chronysockdir to --chronyrundir.
+    - Enable seccomp facility on powerpcspe.
+
+  * debian/chrony.conf:
+    - Make use of the “makestep” directive to step the system clock instead of
+    slewing it when necessary.
+    - Drop the “offline” option as per upstream’s advice to render chrony’s
+    start-up sequence safer.
+
+  * debian/chrony.service:
+    - Reflect init-helper script deletion.
+
+  * debian/copyright:
+    - Add myself as a copyright holder for 2017.
+    - Adjust copyright holders and update some copyright years. Kudos to Paul
+    Gevers <elbrus@debian.org> for spotting the necessary updates.
+
+  * debian/init:
+    - Reflect init-helper script deletion.
+
+  * debian/install:
+    - Don’t install the init-helper script, it has been deleted.
+
+  * debian/README.Debian:
+    - Remove obsolete information.
+
+  * Remove the init-helper script as it no longer needed.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 17 Jan 2017 22:05:31 +0100
+
+chrony (3.0~pre3-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 06 Jan 2017 14:20:13 +0100
+
+chrony (3.0~pre2-2) experimental; urgency=low
+
+  * Merge branch “master”.
+
+  * Enable seccomp facility on powerpcspe.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Tue, 03 Jan 2017 18:17:13 +0100
+
+chrony (3.0~pre2-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre2:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 15 Dec 2016 15:23:44 +0100
+
+chrony (3.0~pre1-1) experimental; urgency=low
+
+  * Import upstream version 3.0-pre1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/copyright:
+    - Mention new files.
+
+  * debian/rules:
+    - Enable support for MS-SNTP authentication in Samba.
+    - Rename --chronysockdir to --chronyrundir.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 10 Dec 2016 16:30:19 +0100
+
+chrony (2.4.1-3) unstable; urgency=medium
+
+  * debian/apm:
+    - Removing that script as APM as been replaced by ACPI long time ago, thus
+    it’s highly probable that it isn’t useful anymore.
+
+  * debian/chrony.maintscript:
+    - Remove the apm script’s conffile.
+
+  * debian/chrony.service:
+    - Supply a systemd service file.
+    - Update unit section’s description. Add chronyc and chrony.conf man pages
+    information and remove reference to “/usr/share/doc/chrony.txt.gz” which
+    is not generated anymore.
+    - Update unit section’s documentation.
+
+  * debian/dirs:
+    - Don’t create etc/apm/event.d as the apm script isn’t provided anymore.
+
+  * debian/init:
+    - Convert to use the init-helper script.
+
+  * debian/init-helper:
+    - Add a helper script that will be used to maintain feature parity between
+    the SysV script and the systemd service file.
+
+  * debian/install:
+    - Install the init-helper script in “/usr/lib/chrony”.
+
+  * debian/rules:
+    - Don’t install the now removed apm script.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 22 Dec 2016 02:16:54 +0100
+
+chrony (2.4.1-2) unstable; urgency=medium
+
+  * debian/chrony.conf:
+    - Don’t create sample histories by default. Using that feature does not
+    make a lot of sense when using a pool of rapidely rotating time servers.
+    - Remove unused directives.
+    - Improve (well, I hope! ;-) ) the configuration file readability.
+    - Reword the driftfile directive commentary.
+    - Shorten the lead-in comment.
+
+  * debian/control:
+    - Build-depend on pps-tools only on linux.
+    - Remove libnss3-dev from Build-Depends until #846012 is fixed.
+
+  * debian/init:
+    - Don’t pass the “-r” option when restarting chronyd as we have disabled
+    the creation of sample histories by default.
+
+  * debian/rules:
+    - Drop dh_auto_build override. Nowadays, the documentation is built by
+    default.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 9 Dec 2016 16:58:32 +0100
+
+chrony (2.4.1-1) unstable; urgency=medium
+
+  * Import upstream version 2.4.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.default:
+    - New file used to pass options to chronyd. Thanks to nutzteil
+    <nutzteil@web.de> for the suggestion and the initial patch.
+    (Closes: #834240)
+
+  * debian/compat:
+    - Bump to debhelper compat 10.
+
+  * debian/control:
+    - Build depend on debhelper ≥ 10.
+
+  * debian/copyright:
+    - Use HTTPS for all URI.
+
+  * debian/init:
+    - Read and execute options assigned to the “DAEMON_OPTS” variable.
+
+  * debian/rules:
+    - Drop dh “--parallel” option. Enabled by default in debhelper 10.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Mon, 21 Nov 2016 12:58:05 +0100
+
+chrony (2.4-1) unstable; urgency=medium
+
+  The “Fix decade-old bug reports” release.
+
+  * Import upstream version 2.4:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/chrony.if-{up,post-down}:
+    - New scripts used to put chronyd online/offline depending on the
+    state of the connection. (Closes: #240528,#312092,#389961)
+
+  * debian/chrony.keys:
+    - Highlight “chronyc keygen” command to generate keys.
+
+  * debian/chrony.ppp.ip-down:
+    - Be sure that there is no default route before going offline.
+    (Closes: #252131)
+
+  * debian/control:
+    - Remove install-info dependency.
+    - Remove texinfo build dependency since documentation in Texinfo format
+    has been dropped upstream.
+    - Build depend on asciidoctor ≥ 1.5.3-1~. The version constraint is
+    important since chrony’s man pages are generated from “adoc” files, a
+    functionality that has been added in asciidoctor 1.5.3.
+
+  * debian/dirs:
+    - Add “etc/NetworkManager/dispatcher.d”.
+
+  * debian/doc-base:
+    - Remove the file since we do not generate chrony.{html,txt} anymore.
+
+  * debian/docs:
+    - Remove references to chrony.{html,txt}.
+
+  * debian/patches/*:
+    - Drop fix-ftbfs-on-powerpc-ppc64-ppc64el.diff; applied upstream.
+    - Update the “series” file accordingly.
+
+  * debian/postinst:
+    - Use ucfr to associate chrony with its configuration files. Suggested by
+    Paul Gevers <elbrus@debian.org>
+
+  * debian/postrm:
+    - Remove all vestiges of the association between chrony and its
+    configuration files. Also suggested by Paul Gevers <elbrus@debian.org>
+
+  * debian/rules:
+    - Provide upstream NetworkManager dispatcher script.
+
+  * debian/watch:
+    - Use HTTPS to fetch new upstream releases.
+    - Switch to version 4 format.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 17 Jun 2016 17:20:08 +0200
+
+chrony (2.3-2) unstable; urgency=low
+
+  * Cherry pick upstream patch to fix FTBFS on PowerPC, ppc64 and ppc64el
+    architectures.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Fri, 20 May 2016 14:21:14 +0200
+
+chrony (2.3-1) unstable; urgency=low
+
+  * Import upstream version 2.3:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+    (Closes: #818235)
+
+  * debian/chrony.conf:
+    - Drop the “logchange” directive. Upstream has enabled “logchange” by
+    default with a threshold of 1 second. We now use that instead of our custom
+    threshold of 0,5 second which tended to spam syslog.
+    - Remove obsolete comment.
+
+  * debian/chrony.lintian-overrides:
+    - Update “chrony.keys” path
+
+  * debian/control:
+    - Bump standard-version to 3.9.8 (no changes required).
+    - Use HTTPS transport protocol for the homepage URL.
+
+  * debian/copyright:
+    - Add some entries about new or untracked files.
+
+  * debian/postinst:
+    - Move /usr/share/chrony/chrony.keys template to /etc/chrony using ucf.
+    - Avoid displaying needless prompt when upgrading to chrony ≥ 2.2.1-1.
+    (Closes: #820087)
+
+  * debian/postrm:
+    - Remove chrony.keys on purge.
+    - Remove all vestiges of chrony.keys from the state hashfile.
+
+  * debian/rules:
+    - Re-enable test suite.
+    - Remove dh_installinit override. The init script is LSB-compliant so
+    passing the “default” option or the two-digit sequence number is unneeded.
+    - Explicitly set the NTP era. With this change, the NTP time will be
+    mapped from 1970-01-01T00:00:00Z to 2106-02-07T06:28:16Z. Thanks to this
+    fixed value, chrony build should be reproducible.
+    - Move the key file template (chrony.keys) in /usr/share/chrony.
+    - Force /usr/share/chrony/chrony.keys to use 0640 modes.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 May 2016 23:13:05 +0200
+
+chrony (2.2.1-1) unstable; urgency=medium
+
+  * Import upstream versions 2.2 and 2.2.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+    - The 2.2.1 release version fixes CVE-2016-1567. (Closes: #812923)
+
+  * debian/chrony.conf:
+    - Drop the commandkey directive. It is obsolete since the introduction of a
+    Unix domain command socket in chrony 2.2.
+    - Fix keyfile directive commentary.
+
+  * debian/chrony.keys:
+    - New file template.
+
+  * debian/chrony.lintian-overrides:
+    - New file used to force lintian to stop complaining about the “chrony.keys”
+    file modes (0640).
+
+  * debian/chrony.ppp.ip-down:
+    - Drop obsolete authentication method to the chronyd daemon. This is now
+    handled by the usage of a Unix domain command socket.
+
+  * debian/chrony.ppp.ip-up:
+    - Drop obsolete authentication method to the chronyd daemon. This is now
+    handled by the usage of a Unix domain command socket.
+    - Reinstate the “burst” chronyc command.
+
+  * debian/control:
+    - Build depend on libseccomp-dev ≥ 2.2.3-3~. We need it to provide syscall
+    filtering.
+    - Fix a typo relative to the name of an architecture.
+    - Build depend on pkg-config.
+    - Restrict libcap-dev build dependency on Linux only.
+    - Depend on iproute2 instead of net-tools.
+    - Drop timelimit dependency.
+    - Update Vcs-Git to use HTTPS.
+    - Bump standard-version to 3.9.7 (no changes required).
+
+  * debian/copyright:
+    - Update copyright year for debian/*.
+
+  * debian/init:
+    - Make use of “ip r” instead of “netstat -rn”. (Closes: #818234)
+    - Delete unused “FLAGS” variable.
+    - Do not execute ip and chronyc through timelimit.
+    - Don’t call chronyc using its absolute path.
+    - Check if the value of the DAEMON variable is executable.
+    - Drop the two seconds delay as it should be unnecessary.
+    - Drop obsolete authentication method from the putonline() function.
+    - Fix indentation issue in the putonline() function.
+
+  * debian/logrotate:
+    - Do not pass the “-a” option to chronyc, it’s no longer necessary.
+
+  * debian/NEWS:
+    - Add a comment about the command key suppression from the “chrony.keys”
+    file.
+
+  * debian/patches/:
+    - Drop 01_do-not-install-copying-file.patch, not needed anymore.
+      ↳ Remove reference to that patch from the series file.
+
+  * debian/postinst:
+    - Do not create an ID/key pair for command authentication. Configuration
+    and monitoring via chronyc is now done using Unix domain socket accessible
+    by root or by the system user to which chronyd will drop root privileges,
+    i.e. _chrony.
+
+  * debian/postrm:
+    - Remove /var/lib/chrony content only on purge. (Closes: #568492)
+
+  * debian/README.Debian:
+    - Drop obsolete statement.
+
+  * debian/rules:
+    - Build with --enable-scfilter.
+    - Install the “chrony.keys” file in /etc/chrony/ with 0640 modes.
+    - Override dh_fixperms to prevent it from modifying modes of the
+    “chrony.keys” file. By default, dh_fixperms tries to set the default modes
+    (0644).
+    - Move the “chronyd.sock” file from /var/run/chrony to /run/chrony.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sat, 19 Mar 2016 14:42:23 +0100
+
+chrony (2.1.1-1) unstable; urgency=medium
+
+  * Import upstream version 2.0 and 2.1.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for the release notes.
+
+  * debian/:
+    - Rename ppp scripts from ip-{up,down} to chrony.ppp.ip-{up,down}.
+    Necessary to let dh_installppp do its magic.
+
+  * debian/chrony.conf:
+    - Use the new 'pool' directive to specify the pool of NTP servers.
+    - Use the iburst option to speed up the initial synchronization.
+    - Drop the minpoll option. There is no point to deviate from upstream here.
+    Consequently, the default minimum polling interval is now 64 seconds
+    instead of 256 seconds.
+    - Enable kernel synchronization of the RTC via the 'rtcsync' directive.
+    - Drop the commented out 'rtcfile' directive in the configuration file.
+    - Stricly act as an NTP client by default. Serving time to other systems
+    should be the decision of the administrator(s). (Closes: #778770)
+    - Clarify some comments.
+    - Improve comment about the 'commandkey' directive.
+
+  * debian/control:
+    - Drop 'Recommends: udev (>= 0.124-1)' since it predates Debian squeeze.
+
+  * debian/copyright:
+    - Update copyright years.
+    - Various cleanups.
+    - Update relative to sys_macosx.{c,h} files.
+    - The test/simulation/test.common file is under the GPL-2+ license.
+    Thanks to Paul Gevers <elbrus@debian.org> for catching it.
+
+  * debian/NEWS:
+    - Comment the deactivation of the NTP server capability by default.
+
+  * debian/patches/:
+    - Refresh 01_do-not-install-copying-file.patch.
+
+  * debian/README.Debian:
+    - Fix misleading information.
+
+  * debian/rules:
+    - No need to install ppp scripts from the 'rules' script. Let dh_installppp
+    handle that.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Wed, 18 Nov 2015 00:11:23 +0100
+
+chrony (1.31.1-2) unstable; urgency=medium
+
+  * Rename the NEWS.Debian file to NEWS. dh_installchangelogs doesn’t seems
+    to be able to deal with the former name.
+
+ -- Vincent Blut <vincent.debian@free.fr>  Thu, 17 Sep 2015 21:50:30 +0200
+
+chrony (1.31.1-1) unstable; urgency=medium
+
+  * Import upstream version 1.31 and 1.31.1:
+    - Please see /usr/share/doc/chrony/changelog.gz for release notes.
+
+  * debian/chrony.conf:
+    - Use the 'hwclockfile' directive. Avoid using text processing methods in
+    the post install script to find out if the RTC keeps local time or UTC.
+    (Closes: #778710)
+
+  * debian/clean:
+    - Add getdate.c
+
+  * debian/control:
+    - Move chrony from admin to net section.
+    - Change priority from extra to optional.
+    - Build depends on libcap-dev. (Closes: #768803)
+    - Bump standards-version to 3.9.6 (no changes required).
+    - Set myself as maintainer and Joachim as uploader.
+    - Update Vcs-Browser URL to use cgit and https.
+    - Build depends on pps-tools. Provides PPSAPI (RFC-2783) support.
+    - Improve the synopsis.
+    - Depend on util-linux (>= 2.20.1-5). Ensure that the 'UTC=' setting
+    from the '/etc/default/rcS' file have been migrated to UTC/LOCAL in
+    '/etc/adjtime'.
+    - Depends on adduser. Needed to create "_chrony" system user/group.
+
+  * debian/copyright:
+    - Add myself to copyright holders.
+    - Remove spaces from short name license (fix Lintian warning)
+    - Filled short license field (RSA-MD) (fix Lintian warning)
+    - Move comment to the "Comment:" field
+
+  * debian/logrotate:
+    - Simplify postrotate script. Thanks to Frédéric Brière
+    <fbriere@fbriere.net> for reporting and diagnosing the issue.
+    (Closes: #763542)
+
+  * debian/patches:
+    - Drop patches for issues fixed upstream.
+    - Rename and update patch. Update the series file accordingly.
+
+  * debian/postinst:
+    - Pass the '--three-way' option to ucf.
+    - Remove useless text processing methods as we now use the 'hwclockfile'
+    directive. (Closes: #778711)
+    - Create "_chrony" system user/group.
+    - Update the "new_file" path in the ucf invocation.
+    - Remove the MAILPASSWORD shell variable as we don’t use it.
+
+  * debian/postrm:
+    - Drop removal instruction of /etc/cron.weekly/chrony.
+    - Remove "_chrony" system user/group on purge.
+    - Don’t pass the --group option to deluser.
+
+  * debian/NEWS.Debian:
+    - New file incorporating worthwhile changes in this release.
+
+  * debian/README.Debian:
+    - Fix typo, thanks to Paul Gevers <elbrus@debian.org> for catching it.
+    - Missing word added.
+
+  * debian/rules:
+    - Build with all hardening flags.
+    - Ease the reading of configure options.
+    - Specify "_chrony" as default chronyd user. This is the system user to
+    which chronyd will drop root privileges. You'll find further information
+    in /usr/share/doc/chrony/README.Debian.
+    (Closes: #688971)
+
+ -- Vincent Blut <vincent.debian@free.fr>  Sun, 6 Sep 2015 22:39:22 +0200
+
+chrony (1.30-2) unstable; urgency=medium
+
+  * With the following security bugfixes (Closes: #782160):
+    - Fix CVE-2015-1853: Protect authenticated symmetric NTP
+                         associations against DoS attacks.
+    - Fix CVE-2015-1821: Fix access configuration with subnet
+                         size indivisible by 4.
+    - Fix CVE-2015-1822: Fix initialization of reply slots for
+                         authenticated commands.
+  * debian/control:
+   - Update e-mail address of myself.
+   - Add Vincent Blut as co-maintainer.
+
+ -- Joachim Wiedorn <joodebian@joonet.de>  Fri, 10 Apr 2015 11:41:31 +0200
+
+chrony (1.30-1) unstable; urgency=medium
+
+  * New upstream release with following bugfixes:
+    - Fix crash when selecting with multiple preferred sources.
+    - Fix frequency calculation with large frequency offsets.
+    - Fix code writing drift and RTC files to compile correctly.
+    - Fix -4/-6 options in chronyc to not reset hostname set by -h.
+    - Fix refclock sample validation with sub-second polling interval.
+    - Set stratum correctly with non-PPS SOCK refclock and local stratum.
+    - Modify dispersion accounting in refclocks to prevent PPS getting
+        stuck with large dispersion and not accepting new samples.
+    - Move faq.txt (PHP style) to a plain text file FAQ. Closes: #415729
+
+  * Add gpg signature of upstream developer for use with uscan.
+  * Update debian/watch, add check of upstream gpg signature.
+  * Update all patches.
+
+  * Bugfix: Use /etc/adjtime in postinst script to recognize
+      UTC hardware clock.  Closes: #680498
+  * Use logrotate instead of cron script. Closes: #323966
+  * debian/rules: disable test simulation.
+
+  * debian/control: remove obsolete build dependency to dpkg-dev.
+  * debian/install, debian/dirs, debian/clean: Update.
+  * debian/copyright: Update and add entries.
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Sun, 10 Aug 2014 19:10:35 +0200
+
+chrony (1.29.1-1) unstable; urgency=high
+
+  * New upstream release with bugfix:
+    - Closes: #737644: Fixing vulnerability:
+        CVE-2014-0021 - traffic amplification in cmdmon protocol
+        (incompatible with previous protocol version, but chronyc
+        supports both).
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Thu, 06 Feb 2014 15:51:47 +0100
+
+chrony (1.29-1) unstable; urgency=medium
+
+  * New upstream release with some bugfixes:
+    - Closes: #719132: new upstream version, fixes security bugs.
+    - Closes: #719203: Fixing vulnerabilities:
+        CVE-2012-4502 - Buffer overflow,
+        CVE-2012-4503 - Uninitialized data.
+
+  * debian/control:
+    - Set myself as new maintainer. Closes: #705768
+    - Bump to Standards-Version 3.9.5.
+    - Move to debhelper >= 9 and compat level 9.
+    - Update package descriptions.
+    - Add Vcs fields to new git repository.
+    - Add dependency to lsb-base (for init script).
+    - Add build dependency to libtomcrypt-dev.
+  * Move to source format 3.0 (quilt).
+  * Add the following patch files:  (Closes: #637514)
+    - 01_fix-small-typo-in-manpages
+    - 03_recreate-always-getdate-c
+    - 04_do-not-look-for-ncurses    (Closes: #646732)
+    - 05_disable-installation-of-license
+  * debian/rules:
+    - Move to dh-based rules file.
+    - Enable parallel builds.
+
+  * Add debian/watch file.
+  * Full update of debian/copyright file.
+  * Add debian/doc-base file.
+  * Full update of debian/README.Debian file.
+  * Update debian/postinst, debian/postrm, debian/prerm.
+  * Remove obsolete debian/preinst. Reduce mailing within postinst.
+  * Do not use old md5sum file anymore for ucf in postinst script.
+  * Add status action in init script (debian/init). Closes: #652207
+  * Add debian/install file for installing example of chrony.conf.
+  * Reduce debian/dirs file for use with debhelper 9.
+
+ -- Joachim Wiedorn <ad_debian@joonet.de>  Fri, 20 Dec 2013 23:35:25 +0100
+
+chrony (1.26-4) unstable; urgency=low
+
+  * QA upload.
+  * Depend on net-tools, for netstat (closes: #707260).
+
+ -- Colin Watson <cjwatson@debian.org>  Mon, 08 Jul 2013 18:00:45 +0100
+
+chrony (1.26-3) unstable; urgency=low
+
+  * Orphaned.
+
+ -- John G. Hasler <jhasler@debian.org>  Fri, 19 Apr 2013 13:08:31 -0500
+
+chrony (1.26-2) unstable; urgency=low
+
+  * Fixed Makefile.in so that getdate.c gets made (and removed
+    in "clean").  This will go upstream.  Moved faq stuff in rules
+    from binary-indep to binary-arch.
+  * Restored accidently deleted nmu changelog entry.
+
+  * Applied patch from Moritz Muehlenhoff <jmm@debian.org>
+    Closes: #655123 Please enabled hardened build flags
+
+  * Fixed upstream.
+    Closes: #518385 Chrony segfaults on startup (narrowed down to
+    chronyc and "burst")
+
+  * Added DEB_BUILD_OPTIONS=noopt to rules.
+    Added build-arch and build-indep to rules.
+    Prefix is now 'usr'.
+    Changed to dh_installman.
+    Fixed "clean:" target.
+    Closes: #479389 Improvements for debian/rules
+
+  * Fixed upstream.
+    Closes: #195620 Strange "System time : xxx seconds slow of NTP time"
+    output
+
+  * Upstream changes should have fixed this.
+    Closes:#294030 chronyd makes the whole system briefly (< 1 second)
+    freeze
+
+  * Fixed by upstream changes and new LSB headers.
+    Closes: #407466 Chrony won't access hardware clock but prevents
+    hwclock from doing so either
+
+ -- John G. Hasler <jhasler@debian.org>  Sun, 01 Jul 2012 22:05:56 -0500
+
+chrony (1.26-1) unstable; urgency=low
+
+  * New upstream release
+    Closes: #348554: chrony and hwclock packages not coordinated.
+    Closes: #572964: RTC support is missing.
+    Closes: #642209: add RTC support for linux 3.0.
+    Closes: #644241: new upstream version 1.26 available.
+
+  * Applied patches from Joachim Wiedorn <ad_debian@joonet.de>:
+    Fixed several typos in man pages and README.
+    Added version.h.
+    Moved default chrony.conf to debian/ .
+    Renamed cron and init files.
+    Removed debian/NEWS.Debian, debian/info.
+    Added debian/clean.
+    Updated debian/copyright.  COPYING stays.  Upstream requires it.
+    Fixed debian/menu, debian/control, updated debian/compat.
+    Added "--without-readline" to debian/rules: rewrite later.
+    Minor fixes to initscript: rewrite later.
+
+    Closes: #646732 Move from readline support to editline support.
+    Closes: #598253 Fix typo in LSB init headers ($hwclock to $time).
+    Closes: #600403 Fix init check with PPP connection.
+
+ -- John G. Hasler <jhasler@debian.org>  Sun, 17 Jun 2012 21:55:47 -0500
+
+chrony (1.24-3.1) unstable; urgency=low
+
+  * Non-maintainer upload.
+  * Add patch (directly over the source...), to work with kernels > 3.0.0,
+    by Paul Martin at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=628919#15.
+    (Closes: #628919)
+  * Fix readline build-depends from "libreadline5-dev | libreadline-dev" to
+    libreadline-gplv2-dev because chrony is GPLv2 only.  (Closes: #634447)
+  * Update copyright file to say that chrony is GPLv2 only. (Closes: #637526)
+
+ -- Ana Beatriz Guerrero Lopez <ana@debian.org>  Fri, 12 Aug 2011 12:32:26 +0200
+
+chrony (1.24-3) unstable; urgency=high
+
+  * Applied (modifed) patch from Gregor Herrmann.
+
+    Closes: #593145: fails to configure on installation
+    Closes: #552162: chrony incorrectly thinks that it has failed to
+    (re)start
+    Closes: #592930: invoke-rc.d: initscript chrony, action "start" failed.
+
+ -- John G. Hasler <jhasler@debian.org>  Tue, 14 Sep 2010 10:06:47 -0500
+
+chrony (1.24-2) unstable; urgency=low
+
+  * Fixed regression that caused default CHRONY_IOC_ lines to
+    vanish from io_linux.h thereby breaking hppa and ia64.
+
+    Closes: #588930: FTBFS [ia64,hppa]: "I don't know the values of the
+    _IOC_* constants on your architecture"
+
+  * $remote_fs was added in 1.24-1.  Depending on networking is neither
+    necessary nor desireable.
+
+    Closes: #590888: Dependencies on init.d script insuficcient
+
+  * Still need to rewrite scripts.
+
+ -- John G. Hasler <jhasler@newsguy.com>  Fri, 30 Jul 2010 20:32:55 -0500
+
+chrony (1.24-1) unstable; urgency=low
+
+  * New upstream release.  The scripts will be rewritten and many more bugs
+    taken care of in -2.  Right now I want to get 1.24 out there.
+
+  * Applied patch from Petter Reinholdtsen to init.d
+
+    Closes: #541806: misses syslog dependency in LSB headers
+
+  * Chrony cannot be linked to libreadline6 because it is GPLv2 only.
+
+    Closes: #553739 replacing libreadline5-dev build dependency with
+    libreadline-dev
+
+  * "configure" rewritten upstream, eliminating "+=".
+
+    Closes: #573036: RTC support disabled (due to Bashism in configure line 293)
+
+  * Removed "install-info" from scripts.
+
+    Closes: #568703: dpkg warnings
+
+  * client.c has been rewritten upstream.
+
+    Closes: #573032
+
+  * Fixed typos.
+
+    Closes: #434629: 'man chrony', 'cronyc', 'cronyd' typos: "parateters" x 2,
+    "priviliges"
+
+  * Added debian/source/format containing "1.0".
+
+ -- John G. Hasler <jhasler@newsguy.com>  Tue, 22 Jun 2010 16:01:29 -0500
+
+chrony (1.23-7) unstable; urgency=high
+
+  * Applied patches from upstream to fix remote DOS:
+
+    CVE-2010-0292 Don't reply to invalid cmdmon packets
+
+    CVE-2010-0293 Limit client log memory size
+
+    CVE-2010-0294 Limit rate of syslog messages
+
+ -- John G. Hasler <jhasler@newsguy.com>  Tue, 02 Feb 2010 19:37:50 -0600
+
+chrony (1.23-6) unstable; urgency=low
+
+  * Commented out rtcfile directive in chrony.conf because it can cause
+    lockups with certain combinations of motherboard and kernel (this is
+    a known kernel bug).
+
+    Closes: #508298: chronyd unreachable and does not work (clock drifts)
+
+  * Chrony no longer uses the ppp/ip-up.d and ppp/ip-up.d files and the new
+    init.d file won't hang if chronyc hangs.
+
+    Closes: #448481: /etc/ppp/ip-up.d/chrony doesn't work when bindaddress is set.
+
+  * Cannot reproduce on current version on amd64.
+
+    Closes: #412961: error in tracking report (on amd64?)
+
+ -- John Hasler <jhasler@debian.org>  Wed, 10 Dec 2008 14:16:37 -0600
+
+chrony (1.23-5) unstable; urgency=low
+
+  * Replaced background kill with 'timelimit' in initscript.
+
+    Closes: #505094: chrony: kills random netstat processes
+
+  * Added 'Recommends: udev (>= 0.124-1)'
+
+    Closes: #497113: /dev/rtc renamed to /dev/rtc0 with linux-image-2.6-*/2.6.26+15
+
+  * Had previously applied patch from Nathanael Nerode to fix configure
+    bug but forgot to close the bug.
+
+    Closes: #392273: Recursive dependency disease: chrony shouldn't depend on ncurses
+
+ -- John Hasler <jhasler@debian.org>  Sun, 09 Nov 2008 20:19:22 -0600
+
+chrony (1.23-4) unstable; urgency=low
+
+  * Fixed dependency of init script on Pppconfig ip-up.d script by moving
+    those lines into the init script.
+
+  * Added checks to try to make sure that Chronyd is really, really running.
+    Changed Netstat call to use -n, added code to kill it if it hangs.
+    Added code to kill Chronyc if it can't contact Chronyd.
+    Discussed the HPET/rtc problem in NEWS.Debian.
+
+    Closes: #504000: init script hangs for a while might break upgrade
+
+  * Added missing initialization to create_instance() in ntp_core.c.
+    This was why UTI_NormaliseTimeval() was being called with huge
+    values at times.
+
+  * See comment on #195620 in 1.21z-6 below.  If you know of more LP64
+    bugs reopen #348412 with a patch.
+
+    Closes: #348412: chronyc not LP64 compliant
+
+  * Added comment about sources being discarded to chrony.conf as suggested
+    by Andreas Hübner in  #268289.
+
+  * This is normal behavior.
+
+    Closes: #287060: trimrtc takes 40 seconds to take effect
+
+ -- John Hasler <jhasler@debian.org>  Thu, 06 Nov 2008 10:38:58 -0600
+
+chrony (1.23-3) unstable; urgency=high
+
+  * Rewrote UTI_NormaliseTimeval()in util.c to use divide/remainder
+    instead of loops at the suggestion of Gabor Gombas.  This prevents the
+    problem of the loop running until the sun goes out when the function
+    is called with a very large value for tv_usec on 64-bit architectures.
+    Also fixed some other spots where the same loop was being used.
+
+    Closes: #474294 Goes into endless loop
+    Closes: #447011 chronyd stalls with 100% CPU usage
+
+    I still don't know why the function is being called with such a
+    large value, however.
+
+  * Changed default servers in chrony,conf to Debian servers.
+
+    Closes: #434483: chrony: Should use NTP servers in Debian pool
+
+ -- John Hasler <jhasler@debian.org>  Sat, 26 Apr 2008 11:47:44 -0500
+
+chrony (1.23-2) experimental; urgency=low
+
+  * Added default IOC's to io_linux.h.
+    Closes: #477043: chrony_1.23-1(ia64/experimental): FTBFS: IOC
+    constants unknown on ia64
+    Closes: #476963: chrony_1.23-1(hppa/experimental): FTBFS: "I don't
+    know the values of the _IOC_* constants for your architecture"
+
+ -- John Hasler <jhasler@debian.org>  Sun, 20 Apr 2008 13:29:29 -0500
+
+chrony (1.23-1) experimental; urgency=low
+
+  * New upstream release
+    This is 1.23 with Debian patches applied (including some for LP64).
+    I'm uploading this to Experimental to get it tested on x86_64 to see
+    if  #474294 is fixed.
+
+ -- John Hasler <jhasler@debian.org>  Sat, 19 Apr 2008 14:49:15 -0500
+
+chrony (1.21z-6) unstable; urgency=low
+
+  * Applied patches from Eric Lammerts <eric@lammerts.org> and Goswin von
+    Brederlow <brederlo@informatik.uni-tuebingen.de> to cast the value
+    returned by ntohl to int32_t and so cause correct sign-extension near
+    line 1655 in client.c.  Also fixed similar bugs in the same area.  I'm
+    not sure this entirely fixes the chronyc number display problem,
+    though.  I've not closed #348412 here because chrony is still not
+    fully LP64 compliant.
+    Closes: #195620: Strange "System time : xxx seconds slow of
+    NTP time" output
+
+  * Replaced addrfilt.c with addrfilt.c from upstream git repository.
+    This fixes the recursive structure definition problems.
+
+  * Replaced 'route' with 'netstat -r' in the initscript.
+
+  * Applied patch for configure script from Nathanael Nerode
+    <neroden@gcc.gnu.org> to delete the superfluous "lncurses" at line
+    327.
+    Closes: #392273: Recursive dependency disease: chrony shouldn't depend
+    on ncurses
+
+  * Added test to reject servers claiming stratum less than 1 in
+    ntp_core.c "Test 7".  Bill Unruh <unruh@physics.ubc.ca> has run across
+    a server that sometimes claims to be stratum 0, which causes
+    considerable confusion.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 16 Feb 2007 17:47:40 -0600
+
+chrony (1.21z-5) unstable; urgency=high
+
+  * Applied postinst patch from Lionel Elie Mamane to test for the
+    existence of old .keys and .conf files before renaming them.
+    Closes: #397759: fails to configure: mv: cannot stat `/etc/chrony/chrony.keys.1.21-2':
+    No such file or directory
+
+  * Added burst command to /etc/ppp/ip-up.d/chrony to give chronyd a kick in the butt.
+    Shouldn't need that, though.
+    Initscript now calls /etc/ppp/ip-up.d/chrony if a default route exists.
+    Closes: #397739: Not connecting to sources after reboot - dialup
+
+ -- John Hasler <jhasler@debian.org>  Sun, 26 Nov 2006 08:07:20 -0600
+
+chrony (1.21z-4) unstable; urgency=low
+
+  * Added test for /usr/bin/mail to postinst.
+    Closes: #386651: chrony: Requires /usr/bin/mail but doesn't depend on it
+    Closes: #390280: chrony: missing dependency on mail
+
+  * Added LSB headers to initscript
+
+  * Corrected erroneous use of 'dpkg --compare-version' in preinst and postinst.
+    Closes: #386733: fails to configure (bad upgrade check)
+
+  * Added rm to postinst to remove keyfile possibly left by a failed install.
+    Closes: #390278: usage of tempfile /etc/chrony/chrony.keys is doubtful
+
+ -- John Hasler <jhasler@debian.org>  Sat,  7 Oct 2006 13:39:49 -0500
+
+chrony (1.21z-3) unstable; urgency=low
+
+  * Changed upstream version number from 1.21 to 1.21z to satisfy Debian
+    archive software.
+
+  * Replaced impure chrony_1.21.orig.tar.gz.
+    Closes: #340030: chrony: Tarball is impure
+
+  * Now Provides, Conflicts, Replaces time-daemon
+    Closes: #330839: time-daemon pseudopackage
+
+  * Corrected typos.
+    Closes: #321121: chrony: typo in 'Conflicts:' field: s/ntpsimple/ntp-simple/ and s/ntprefclock/ntp-refclock/
+
+  * Rewrote postinst and postrm to use ucf.  Wrote preinst to protect chrony.conf from dpkg.
+    Closes: #351332: chrony: conffile change prompt prevents smooth upgrade from sarge to etch
+
+  * Deleted last few lines of chrony.conf as they no longer apply.
+
+  * Deleted .arch-ids from contrib and examples.
+
+  * Fixed typo in chronyc.1
+    Closes: #349871: chrony: typo in chrnoyc.1 results in missing word
+
+  * Corrected references in man pages.
+    Closes: #345034: chrony: man pages refer to wrong sections
+
+  * Added "allow 172.16/12" to chrony.conf.
+    Closes: #252952: chrony: default allow should also have 172.16/12
+
+  * Channged server lines in chrony.conf to follow ntp.org current recommendation.
+    Closes: #243534: chrony: new pool.ntp.org setup doesn't work well
+
+  * Fixed FSF address in debian/copyright.
+
+ -- John Hasler <jhasler@debian.org>  Fri,  1 Sep 2006 10:52:52 -0500
+
+chrony (1.21-2) unstable; urgency=high
+
+  * Patched io_linux.h to add missing architectures.
+    Closes: #339764: chrony - FTBFS: #error "I don't know the values of the
+    _IOC_* constants for your architecture"
+
+  * Fixed brown-bag error in rules.
+    Closes: #339853: /usr/sbin/chronyd is missing
+
+ -- John Hasler <jhasler@debian.org>  Sat, 19 Nov 2005 10:12:49 -0600
+
+chrony (1.21-1) unstable; urgency=low
+
+  * New upstream release
+    Closes: #328292: New version of chrony avalaible
+    Closes: #301592: Fails to read RTC and floods logfiles
+
+  * Enabled RTC as upstream has installed a work-around for the HPET bug.
+
+  * Switched to libreadline5.
+    Closes: #326379: please rebuild with libreadline5-dev as build dependency
+
+  * Patched addrfilt.c to fix gcc 4.0 build problem.
+    Closes: #298709: chrony: FTBFS (amd64/gcc-4.0): array type has incomplete element type
+
+  * There are lots more minor things to fix but I'm uploading now to close
+    the serious bugs.  I'll upload another version with some improvements
+    in a few weeks.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 15 Nov 2005 18:39:49 -0600
+
+chrony (1.20-8) unstable; urgency=high
+
+  * Added test for /usr/bin/mail in postinst.
+    Closes: #307061: Install failure: Cannot configure on system without mailx
+    I consider this bug serious because it can cause installation to fail
+    and so I want to get the fix into Sarge.
+
+  * Fixed typo in chrony.conf, replaced '/etc/init.d/chrony restart'
+    with 'invoke-rc.d chrony restart'.
+    Closes: #305090: Typo in chrony.conf, should mention invoke-rc.d
+
+  * Added README.Debian explaining that rtc is off by default.
+
+ -- John Hasler <jhasler@debian.org>  Sat, 30 Apr 2005 18:47:30 -0500
+
+chrony (1.20-7) unstable; urgency=low
+
+  * Added info-4 to debian/rules.
+    Closes: #287142: chrony: Can't find chrony.info-4
+
+  * Corrected "See Also" section in chrony man page.  Now mentions
+    chronyc(1), chronyd(8), and chrony.conf(5).
+    Closes: #287444: chrony.1.gz: SEE ALSO on man page has wrong section.
+
+  * Edited chrony.conf to disable rtc by default and explain why:
+    on some systems that use genrtc or the HPET real-time clock it
+    fails and causes chronyd to fill up the log.  The failure is
+    probably due to a kernel bug, bug the logging should be
+    throttled.
+
+  * Added more explanatory comments at the servers directive in
+    chrony.conf.
+
+  * The postinst script now sends a message to root saying where the
+    password is, whether Chrony is assuming UTC or local time,
+    that rtc updating is disabled, why, and how to change it.
+
+  * Added missing '#' to
+    "Can't tell how your clock is set: assuming local time."
+    in postinst.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 12 Apr 2005 17:59:13 -0500
+
+chrony (1.20-6) unstable; urgency=low
+
+  * Fixed error in chrony.conf where the non-existent 'online' directive
+    was mentioned.
+    Closes: #257235 misleading instructions in chrony.conf
+
+  * Patched Makefile.in to generate faq.html.
+    Closes: #265936 /usr/share/doc/chrony/faq.txt.gz: how to read?
+
+ -- John Hasler <jhasler@debian.org>  Sat,  4 Dec 2004 17:47:31 -0600
+
+chrony (1.20-5) unstable; urgency=low
+
+  * Put pool.ntp.org servers in chrony.conf as defaults.
+
+  * Fixed erroneous references to chronyd(1) in some man pages.
+    Closes: #241746 SEE ALSO chronyd(1) should be (8)
+
+  * I got a new motherboard and can no longer reproduce this.
+    If you can please reopen the bug.
+    Closes: #223518 Rtc stuff is broken
+
+  * Edited chrony.conf(5).
+    Closes:  #241745 many more features have been added
+
+  * Edited chrony.conf to add logchange and mailonchange and to
+    enable rtc by default.
+    Closes: #226644 /etc/chrony/chrony.conf: rtc; not all options are noted in conf file
+
+  * Fixed upstream: see NEWS.
+    Closes: #124089 mistake in the chrony manual
+    Closes: #177366: trailing blank on log lines
+    Closes: #195618 failure to use /dev/misc/rtc floods logfiles
+    Closes: #53066 "acquisitionport" directive and doc fixes [patch]
+    Closes: #100880 RFE: don't use /proc when uname(2) will do
+    Closes: #163470: different bindaddresses for ntp port and control port
+    Closes: #200174: Chrony breaks under Kernel 2.5 (two bugs)
+
+ -- John Hasler <jhasler@debian.org>  Sat, 10 Apr 2004 22:00:00 -0500
+
+chrony (1.20-4) unstable; urgency=low
+
+  * Added '#include <asm/types>' to rtc_linux.c to fix Alpha build problem.
+    Also removed spinlock stuff from configure.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 26 Dec 2003 21:00:00 -0600
+
+chrony (1.20-3) unstable; urgency=low
+
+  * Removed all inclusions of kernel headers.
+    Hopefully Chrony will now build on m68k.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 23 Dec 2003 19:00:00 -0600
+
+chrony (1.20-2) unstable; urgency=low
+
+  * Removed spinlock.h and mc146818.h from rtc_linux.c.  linux/rtc.h and
+    RTC_UIE=0x10 provide everything needed now.
+    Closes: #223134 FTBFS: Errors in kernel headers
+
+  * However, rtc is now broken (and appears to have been broken for some time)
+    on 440BX chipsets with 2.4 kernels.
+
+ -- John Hasler <jhasler@debian.org>  Fri, 12 Dec 2003 13:00:00 -0600
+
+chrony (1.20-1) unstable; urgency=low
+
+  * New upstream release.
+
+  * Frank Otto's patch to sys_linux.c, function guess_hz_and_shift_hz now
+    incorporated upstream.
+    Closes: #198557 Fatal error: chronyd can't determine hz for kernel with HZ=200
+
+  * Security and 64 bit patches are now incorporated upstream
+    along with most non-i386 architecture patches.
+
+  * Put correct links in /usr/share/doc/chrony/timeservers.
+    Closes: #189686 /usr/share/doc/timeservers links are broken
+
+  * Put correct links in chrony.conf.
+    Closes: #210886 bad link in chrony.conf
+
+  * Put missing newlines in apm and chrony.keys.
+    Closes: #211604 Build-warning: some files misses final newline
+
+  * Removed conflict with ntpdate.
+
+ -- John Hasler <jhasler@debian.org>  Tue, 7 Oct 2003 22:00:00 -0500
+
+chrony (1.19-10) unstable; urgency=low
+
+  * Put linux/linkage.h ahead of linux/spinlock.h as I meant to in
+    the first place.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 13 Jul 2003 7:00:00 -0500
+
+chrony (1.19-9) unstable; urgency=low
+
+  * Added "#include <linux/linkage.h>" to rtc_linux.c to fix mips
+    build failure.
+    Closes: #200165 chrony doesn't build on mips and mipsel
+
+ -- John Hasler <john@dhh.gt.org>  Sat, 12 Jul 2003 10:00:00 -0500
+
+chrony (1.19-8) unstable; urgency=low
+
+  * Added bison to build-depends because of addition of getdate.y
+
+ -- John Hasler <john@dhh.gt.org>  Tue, 3 Jun 2003 10:00:00 -0500
+
+chrony (1.19-7) unstable; urgency=high
+
+  * Closes: #186498 chronyc hangs if no chronyd is running
+    Added test for running daemon to ip-{up|down} scripts.
+    Disabled trimrtc for ALPHA
+    Closes: #195615 GPL violation - generated file without source
+  * Added a copy of getdate.y to source.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 1 Jun 2003 7:00:00 -0500
+
+chrony (1.19-6) unstable; urgency=low
+
+  * Closes: #179842 "CROAK" redefined
+    Added '#undef CROAK' before CROAK redefiniton in pktlength.h,
+    added '-DALPHA' to 'alpha' condition in configure, added
+    'ifdef ALPHA' around CROAK redefinition.
+  * Replaced many signed and unsigned longs as well as some ints,
+    shorts, and chars with stdint.h types in candm.h, md5.h, ntp.h,
+    clientlog.h, and ntp_io.c.  This should fix all 64-bit problems.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 14 Mar 2003 19:00:00 -0600
+
+chrony (1.19-5) unstable; urgency=high
+
+  * Closes: #184065 Assertion `sizeof(NTP_int32) == 4' failed on alpha
+    Fixed several spots where the author assumed that a long is 32 bits.
+    There are many more misuses of long as well as several of short and
+    char but I think I got the only ones likely to cause trouble.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 14 Mar 2003 11:00:00 -0600
+
+chrony (1.19-4) unstable; urgency=low
+
+  * Closes: #179538 FTBFS: missing build-depends on makeinfo
+    Added texinfo to build-depends.
+  * CLoses: #179508: chrony(c|d) show wrong version numbers
+    Removed spurious version.h.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 2 Feb 2003 19:00:00 -0600
+
+chrony (1.19-3) unstable; urgency=low
+
+  * Updated author's address in copyright file.
+  * Closes:  #163446 patch, that scripts can handle all commandkeys
+    Applied debugged patch.
+  * Closes: #107863 doesn't know about APM
+    Put apm script in debian/ and added rules to copy it to
+    etc/apm/event.d as instructed by the apmd maintainer.
+
+ -- John Hasler <john@dhh.gt.org>  Fri, 31 Jan 2003 18:00:00 -0600
+
+chrony (1.19-2) unstable; urgency=low
+
+  * Closes: #100879 unnecessary dependency on libm
+    Applied patch from Zack Weinberg <zack@codesourcery.com>
+  * Closes: #124091 the force-reload command of /etc/init.d/chrony should
+    use the -r option.
+    Added -r option.
+
+ -- John Hasler <john@dhh.gt.org>  Wed, 29 Jan 2003 10:00:00 -0600
+
+chrony (1.19-1) unstable; urgency=low
+
+  * New upstream release.
+  * Closes: #178338 New upstream version fixes crashes caused by adjtimex
+    failure
+  * Closes: #178101 /etc/ppp/ip-{up,down}.d/chrony installed with
+    incorrect permissions
+    This bug was previously reported and fixed in 18-1
+  * Closes: #176130 got an error when I use ppp_on_boot
+    Changed 'update-rc.d chrony defaults 83' to
+    'update-rc.d chrony defaults 14' in init.d so that chrony
+    will come up before ppp.
+  * Added code to postinst to read /etc/default/rcS and
+    set rtconutc appropriately in chrony.conf.
+  * Rewrote password generator in postinst.
+  * Closes: #100879 unnecessary dependency on libm
+    I don't know why this wasn't closed months ago.
+  * Closes: #103447 typo in "/etc/init.d/chrony"
+  * Closes: #124087 problems with /etc/init.d/chrony
+    Fixed script.
+  * Closes: #161350 /etc/ppp/ip-down.d/chrony cat unnecessary
+    Fixed scripts.
+  * Closes: #113840 ntp has been split - add conflicts?
+    Added ntp-simple and ntp-refclock to conflicts.
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 26 Jan 2003 15:00:00 -0600
+
+chrony (1.18-2) unstable; urgency=low
+
+  * Corrects error in changelog which resulted
+    in uploads being erroneously classified as NMUs.
+  * Closes: #138142, #104774, #142670, #105344, #101039
+  * Closes: #162427, #56756, #98951, #99799, #139633
+  * Closes: #163469, #163408, #167416
+
+ -- John Hasler <john@dhh.gt.org>  Sun, 3 Nov 2002 20:00:00 -0600
+
+chrony (1.18-1) unstable; urgency=low
+
+  * New upstream release.
+  * Closes: #138142 new upstream release
+  * Added Mark Brown's Alpha and PowerPC patch.
+  * Closes: #104774 hppa build failure
+    Applied patch.
+  * Closes: #142670 compilation errors on sparc
+    Applied patch.
+  * Closes: #105344 ip-{up, down}.d/chrony not executable
+    Fixed debian/rules.
+  * Closes: #101039 does not run on Alpha
+    Fixed by above mentioned Mark Brown patch.
+  * Closes: #162427 description should mention NTP
+    Fixed description.
+  * Closes: #56756 README.debian should caution about hwclock
+    Fixed README.debian.
+  * Closes: #98951 no chrony.keys file installed
+    Not reproducible, probable user error.
+  * Closes: #99799 logs world readable
+    Added umask 022 to log script.
+  * Closes: #139633 documentation error
+    Added rtconutc to chrony.conf.
+  * Closes: #163469 no default case in init.d script
+    Corrected typo.
+  * Closes: #163408 PIDFILE wrongly defined in ip-{up,down}
+    No chrony script uses any such variable.
+  * Closes: #167416 needs Build-Depends: libreadline4-dev
+
+ --  <john@dhh.gt.org>  Sun, 3 Nov 2002 10:00:00 -0600
+
+chrony (1.14-7) unstable; urgency=medium
+
+  * Changed rtc_linux.c to not include linux/mc146818rtc.h
+    when building for sparc, because Moshe Zadka says this
+    will allow chrony to build there.
+  * Closes: #142670
+
+ --  <jhasler@debian.org>  Wed, 17 Apr 2002 17:00:00 -0500
+
+chrony (1.14-6) unstable; urgency=low
+
+  * Changed architecture back to 'any'.
+  * Applied portability patch from LaMont Jones.
+  * Closes: #104774
+
+ --  <jhasler@debian.org>  Mon, 1 Apr 2002 21:00:00 -0600
+
+chrony (1.14-5) unstable; urgency=low
+
+  * Changed architecture from 'any' to 'i386 sparc'.
+    Neither I nor the author can test on anything but i386.  If
+    you want chrony on anything else send me a tested patch.
+  * Closes: #101039
+  * Closes: #104774
+
+ --  <john@dhh.gt.org>  Fri, 28 Dec 2001 20:10:00 -0600
+
+chrony (1.14-4) unstable; urgency=low
+
+  * Fixed bug in man pages.
+  * Closes: #95134
+
+ --  <john@dhh.gt.org>  Tue, 24 Apr 2001 20:10:00 -0500
+
+chrony (1.14-3) unstable; urgency=low
+
+  * Replaced <linux/spinlock.h> in rtc_linux.c with
+    typedef int spinlock_t as suggested by Paul Slootman.
+  * Put #define CROAK(message) assert(0) in pktlength.h
+    to fix Alpha build problem.
+  * Closes: #86991
+
+ --  <john@dhh.gt.org>  Sat, 24 Feb 2001 22:45:00 -0600
+
+chrony (1.14-2) unstable; urgency=low
+
+   * Closes: #84597
+
+ --  <john@dhh.gt.org>  Sat, 3 Feb 2001 21:25:00 -0600
+
+chrony (1.14-1) unstable; urgency=low
+
+   * New upstream release.
+   * Fixed more sprintfs.
+   * Closes: #50793, #52570, #48216, #65209, #62924, #70377, #61485, #76661
+
+ --  <john@dhh.gt.org>  Mon, 20 Nov 2000 20:25:00 -0600
+
+chrony (1.10-3) unstable; urgency=low
+
+   * Patched cron,weekly script with (corrected) patch
+     from Rene H. Larsen <renehl@post1.tele.dk>.
+   * Updated author address in copyright file.
+   * Compiled with egcs.
+   * Closes: #41885, #41551
+
+ --  <john@dhh.gt.org>  Sun, 25 July 1999 12:14:00 -0500
+
+chrony (1.10-2) unstable; urgency=low
+
+   * Patched rtc_linux.c with patch for SPARC from
+     bmc@visi.net.
+
+ --  <john@dhh.gt.org>  Mon, 17 May 1999 22:30:00 -0500
+
+chrony (1.10-1) unstable; urgency=low
+
+   * New upstream release.
+   * Upstream version number is 1.1.  Debian version
+     number is 1.10 because previous upstream number
+     was 1.02.
+
+ --  <john@dhh.gt.org>  Wed, 12 May 1999 20:30:00 -0500
+
+chrony (1.02-7) unstable; urgency=low
+
+   * Changed configure to permit building on non-Intel.
+
+ --  <john@dhh.gt.org>  Wed, 5 May 1999 18:00:00 -0500
+
+chrony (1.02-6) unstable; urgency=low
+
+   * Fixed postrm bug.
+
+ --  <john@dhh.gt.org>  Thur, 29 Apr 1999 18:00:00 -0500
+
+chrony (1.02-5) unstable; urgency=low
+
+   * Fixed bugs 34954 and 36921.
+   * Moved to priority extra.
+   * Added README.debian text about rtc.
+
+ --  <john@dhh.gt.org>  Thur, 15 Apr 1999 21:30:00 -0500
+
+chrony (1.02-4) unstable; urgency=low
+
+   * Replaced sprintf's with snprintf's.
+
+ --  <john@dhh.gt.org>  Sun,  28 Feb 1999 16:53:00 -0600
+
+chrony (1.02-3) unstable; urgency=low
+
+   * Fixed bugs in cron.weekly, ip-up.d, and ip-down.d.
+   * Bug 29981 is also fixed.
+
+ --  <john@dhh.gt.org>  Sun,  6 Dec 1998 9:53:00 -0600
+
+chrony (1.02-2) unstable; urgency=low
+
+  * Added cron.weekly.
+  * Changed ip-up.d, ip-down.d, and cron.weekly to read the
+    password from chrony.keys.
+  * Added code to postinst to generate a random password and
+    put it in chrony.keys.
+
+ --  <john@dhh.gt.org>  Thur,  3 Dec 1998 19:00:08 -0600
+
+chrony (1.02-1) unstable; urgency=low
+
+  * Initial Release.
+
+ --  <john@dhh.gt.org>  Fri,  6 Nov 1998 23:00:08 -0600
diff --git a/chrony-dnssrv@.service b/chrony-dnssrv@.service
new file mode 100644
index 0000000..86d374f
--- /dev/null
+++ b/chrony-dnssrv@.service
@@ -0,0 +1,17 @@
+[Unit]
+Description=DNS SRV lookup of %I for chrony
+After=chrony.service network-online.target
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/chrony/chrony-helper update-dnssrv-servers %I
+ProtectSystem=strict
+PrivateDevices=yes
+ProtectHome=yes
+ReadWritePaths=/run
+PrivateTmp=yes
+PrivateDevices=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
diff --git a/chrony-dnssrv@.timer b/chrony-dnssrv@.timer
new file mode 100644
index 0000000..8495e01
--- /dev/null
+++ b/chrony-dnssrv@.timer
@@ -0,0 +1,9 @@
+[Unit]
+Description=Periodic DNS SRV lookup of %I for chrony
+
+[Timer]
+OnActiveSec=0
+OnUnitInactiveSec=1h
+
+[Install]
+WantedBy=timers.target
diff --git a/chrony-helper b/chrony-helper
new file mode 100755
index 0000000..5099161
--- /dev/null
+++ b/chrony-helper
@@ -0,0 +1,264 @@
+#!/bin/bash
+# This script configures running chronyd to use NTP servers obtained from
+# DHCP and _ntp._udp DNS SRV records. Files with servers from DHCP are managed
+# externally (e.g. by a dhclient script). Files with servers from DNS SRV
+# records are updated here using the dig utility. The script can also list
+# and set static sources in the chronyd configuration file.
+#
+# Modified for Debian by Vincent Blut <vincent.debian@free.fr>.
+
+chronyc=/usr/bin/chronyc
+chrony_conf=/etc/chrony/chrony.conf
+chrony_service=chrony.service
+helper_dir=/run/chrony-helper
+added_servers_file=$helper_dir/added_servers
+
+dhclient_servers_files="/var/lib/dhcp/chrony.servers.*"
+dnssrv_servers_files="$helper_dir/dnssrv@*"
+dnssrv_timer_prefix=chrony-dnssrv@
+
+chrony_command() {
+    $chronyc -n -m "$1"
+}
+
+is_running() {
+    chrony_command "tracking" &> /dev/null
+}
+
+get_servers_files() {
+    echo "$dhclient_servers_files"
+    echo "$dnssrv_servers_files"
+}
+
+is_update_needed() {
+    for file in $(get_servers_files) $added_servers_file; do
+        [ -e "$file" ] && return 0
+    done
+    return 1
+}
+
+update_daemon() {
+    local all_servers_with_args all_servers added_servers
+
+    if ! is_running; then
+        rm -f $added_servers_file
+        return 0
+    fi
+
+    all_servers_with_args=$(cat $(get_servers_files) 2> /dev/null)
+
+    all_servers=$(
+        echo "$all_servers_with_args" |
+            while read -r server serverargs; do
+                echo "$server"
+            done | sort -u)
+    added_servers=$( (
+        cat $added_servers_file 2> /dev/null
+        echo "$all_servers_with_args" |
+            while read -r server serverargs; do
+                [ -z "$server" ] && continue
+                chrony_command "add server $server $serverargs" &> /dev/null &&
+                    echo "$server"
+            done) | sort -u)
+
+    comm -23 <(echo -n "$added_servers") <(echo -n "$all_servers") |
+        while read -r server; do
+            chrony_command "delete $server" &> /dev/null
+        done
+
+    added_servers=$(comm -12 <(echo -n "$added_servers") <(echo -n "$all_servers"))
+
+    if [ -n "$added_servers" ]; then
+        echo "$added_servers" > $added_servers_file
+    else
+        rm -f $added_servers_file
+    fi
+}
+
+get_dnssrv_servers() {
+    local name=$1 output
+
+    if ! command -v dig &> /dev/null; then
+        echo "Missing dig (DNS lookup utility)" >&2
+        return 1
+    fi
+
+    output=$(dig "$name" srv +short +ndots=2 +search 2> /dev/null) || return 0
+
+    echo "$output" | while read -r _ _ port target; do
+        server=${target%.}
+        [ -z "$server" ] && continue
+        echo "$server port $port iburst"
+    done
+}
+
+check_dnssrv_name() {
+    local name=$1
+
+    if [ -z "$name" ]; then
+        echo "No DNS SRV name specified" >&2
+        return 1
+    fi
+
+    if [ "${name:0:9}" != _ntp._udp ]; then
+        echo "DNS SRV name $name doesn't start with _ntp._udp" >&2
+        return 1
+    fi
+}
+
+update_dnssrv_servers() {
+    local name=$1
+    local srv_file=$helper_dir/dnssrv@$name servers
+
+    check_dnssrv_name "$name" || return 1
+
+    servers=$(get_dnssrv_servers "$name")
+    if [ -n "$servers" ]; then
+        echo "$servers" > "$srv_file"
+    else
+        rm -f "$srv_file"
+    fi
+}
+
+set_dnssrv_timer() {
+    local state=$1 name=$2
+    local srv_file=$helper_dir/dnssrv@$name servers
+    local timer
+
+    timer=$dnssrv_timer_prefix$(systemd-escape "$name").timer || return 1
+
+    check_dnssrv_name "$name" || return 1
+
+    if [ "$state" = enable ]; then
+        systemctl enable "$timer"
+        systemctl start "$timer"
+    elif [ "$state" = disable ]; then
+        systemctl stop "$timer"
+        systemctl disable "$timer"
+        rm -f "$srv_file"
+    fi
+}
+
+list_dnssrv_timers() {
+    systemctl --all --full -t timer list-units | grep "^$dnssrv_timer_prefix" | \
+            sed "s|^$dnssrv_timer_prefix\(.*\)\.timer.*|\1|" |
+        while read -r name; do
+            systemd-escape --unescape "$name"
+        done
+}
+
+prepare_helper_dir() {
+    mkdir -p $helper_dir
+    exec 100> $helper_dir/lock
+    if ! flock -w 20 100; then
+        echo "Failed to lock $helper_dir" >&2
+        return 1
+    fi
+}
+
+is_source_line() {
+    local pattern="^[ \t]*(server|pool|peer|refclock)[ \t]+[^ \t]+"
+    [[ "$1" =~ $pattern ]]
+}
+
+list_static_sources() {
+    while read -r line; do
+        if is_source_line "$line"; then
+            echo "$line"
+        fi
+    done < $chrony_conf
+}
+
+set_static_sources() {
+    local new_config tmp_conf
+
+    new_config=$(
+        sources=$(
+            while read -r line; do
+                is_source_line "$line" && echo "$line"
+            done)
+
+        while read -r line; do
+            if ! is_source_line "$line"; then
+                echo "$line"
+                continue
+            fi
+
+            tmp_sources=$(
+                local removed=0
+
+                echo "$sources" | while read -r line2; do
+                    if [ "$removed" -ne 0 ] || [ "$line" != "$line2" ]; then
+                        echo "$line2"
+                    else
+                        removed=1
+                    fi
+                done)
+
+            [ "$sources" == "$tmp_sources" ] && continue
+            sources=$tmp_sources
+            echo "$line"
+        done < $chrony_conf
+
+        echo "$sources"
+    )
+
+    tmp_conf=${chrony_conf}.tmp
+
+    cp -a $chrony_conf $tmp_conf &&
+        echo "$new_config" > $tmp_conf &&
+        mv $tmp_conf $chrony_conf || return 1
+
+    systemctl try-restart $chrony_service
+}
+
+print_help() {
+    echo "Usage: $0 COMMAND"
+    echo
+    echo "Commands:"
+    echo "	update-daemon"
+    echo "	update-dnssrv-servers NAME"
+    echo "	enable-dnssrv NAME"
+    echo "	disable-dnssrv NAME"
+    echo "	list-dnssrv"
+    echo "	list-static-sources"
+    echo "	set-static-sources < sources.list"
+    echo "	is-running"
+    echo "	command CHRONYC-COMMAND"
+}
+
+case "$1" in
+    update-daemon|add-dhclient-servers|remove-dhclient-servers)
+        is_update_needed || exit 0
+        prepare_helper_dir && update_daemon
+        ;;
+    update-dnssrv-servers)
+        prepare_helper_dir && update_dnssrv_servers "$2" && update_daemon
+        ;;
+    enable-dnssrv)
+        set_dnssrv_timer enable "$2"
+        ;;
+    disable-dnssrv)
+        set_dnssrv_timer disable "$2" && prepare_helper_dir && update_daemon
+        ;;
+    list-dnssrv)
+        list_dnssrv_timers
+        ;;
+    list-static-sources)
+        list_static_sources
+        ;;
+    set-static-sources)
+        set_static_sources
+        ;;
+    is-running)
+        is_running
+        ;;
+    command|forced-command)
+        chrony_command "$2"
+        ;;
+    *)
+        print_help
+        exit 2
+esac
+
+exit $?
diff --git a/chrony.conf b/chrony.conf
new file mode 100644
index 0000000..bd63609
--- /dev/null
+++ b/chrony.conf
@@ -0,0 +1,47 @@
+# Welcome to the chrony configuration file. See chrony.conf(5) for more
+# information about usable directives.
+
+# Include configuration files found in /etc/chrony/conf.d.
+confdir /etc/chrony/conf.d
+
+# Use Debian vendor zone.
+pool 2.debian.pool.ntp.org iburst
+
+# Use time sources from DHCP.
+sourcedir /run/chrony-dhcp
+
+# Use NTP sources found in /etc/chrony/sources.d.
+sourcedir /etc/chrony/sources.d
+
+# This directive specify the location of the file containing ID/key pairs for
+# NTP authentication.
+keyfile /etc/chrony/chrony.keys
+
+# This directive specify the file into which chronyd will store the rate
+# information.
+driftfile /var/lib/chrony/chrony.drift
+
+# Save NTS keys and cookies.
+ntsdumpdir /var/lib/chrony
+
+# Uncomment the following line to turn logging on.
+#log tracking measurements statistics
+
+# Log files location.
+logdir /var/log/chrony
+
+# Stop bad estimates upsetting machine clock.
+maxupdateskew 100.0
+
+# This directive enables kernel synchronisation (every 11 minutes) of the
+# real-time clock. Note that it can't be used along with the 'rtcfile' directive.
+rtcsync
+
+# Step the system clock instead of slewing it if the adjustment is larger than
+# one second, but only in the first three clock updates.
+makestep 1 3
+
+# Get TAI-UTC offset and leap seconds from the system tz database.
+# This directive must be commented out when using time sources serving
+# leap-smeared time.
+leapsectz right/UTC
diff --git a/chrony.default b/chrony.default
new file mode 100644
index 0000000..028f63d
--- /dev/null
+++ b/chrony.default
@@ -0,0 +1,6 @@
+# This is a configuration file for /etc/init.d/chrony and
+# /lib/systemd/system/chrony.service; it allows you to pass various options to
+# the chrony daemon without editing the init script or service file.
+
+# Options to pass to chrony.
+DAEMON_OPTS="-F 1"
diff --git a/chrony.dhcp b/chrony.dhcp
new file mode 100644
index 0000000..f3dacd7
--- /dev/null
+++ b/chrony.dhcp
@@ -0,0 +1,27 @@
+CHRONY_SOURCEDIR=/run/chrony-dhcp
+SERVERFILE=$CHRONY_SOURCEDIR/$interface.sources
+
+chrony_config() {
+    rm -f "$SERVERFILE"
+    mkdir -p "$CHRONY_SOURCEDIR"
+    for server in $new_ntp_servers; do
+        echo "server $server iburst" >> "$SERVERFILE"
+    done
+    /usr/bin/chronyc reload sources > /dev/null 2>&1 || :
+}
+
+chrony_restore() {
+    if [ -f "$SERVERFILE" ]; then
+        rm -f "$SERVERFILE"
+        /usr/bin/chronyc reload sources > /dev/null 2>&1 || :
+    fi
+}
+
+case $reason in
+    BOUND|RENEW|REBIND|REBOOT)
+        chrony_config
+        ;;
+    EXPIRE|FAIL|RELEASE|STOP)
+        chrony_restore
+        ;;
+esac
diff --git a/chrony.examples b/chrony.examples
new file mode 100644
index 0000000..1a0e8e2
--- /dev/null
+++ b/chrony.examples
@@ -0,0 +1 @@
+examples/chrony.conf*
diff --git a/chrony.if-post-down b/chrony.if-post-down
new file mode 100644
index 0000000..4cc0796
--- /dev/null
+++ b/chrony.if-post-down
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -e
+
+[ -x /usr/sbin/chronyd ] || exit 0
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.if-up b/chrony.if-up
new file mode 100644
index 0000000..4cc0796
--- /dev/null
+++ b/chrony.if-up
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -e
+
+[ -x /usr/sbin/chronyd ] || exit 0
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.keys b/chrony.keys
new file mode 100644
index 0000000..a2d655d
--- /dev/null
+++ b/chrony.keys
@@ -0,0 +1,10 @@
+# This file is solely used for NTP authentication with symmetric keys
+# as defined by RFC 1305 and RFC 5905.
+#
+# It can contain ID/key pairs which can be generated using the “keygen” option
+# from “chronyc”; for example:
+# chronyc keygen 1 SHA256 256 >> /etc/chrony/chrony.keys
+# would generate a 256-bit SHA-256 key using ID 1.
+#
+# A list of supported hash functions and output encoding is available by
+# consulting the "keyfile" directive in the chrony.conf(5) man page.
diff --git a/chrony.lintian-overrides b/chrony.lintian-overrides
new file mode 100644
index 0000000..83260a6
--- /dev/null
+++ b/chrony.lintian-overrides
@@ -0,0 +1,7 @@
+# The “chrony.keys” file must not be world readable as it could contain
+# symmetric keys used for NTP authentication.
+chrony: non-standard-file-perm 0640 != 0644 [usr/share/chrony/chrony.keys]
+
+# NetworkManager does not execute dispatcher scripts in /usr/libexec.
+chrony: executable-in-usr-lib [usr/lib/NetworkManager/dispatcher.d/20-chrony-dhcp]
+chrony: executable-in-usr-lib [usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline]
diff --git a/chrony.maintscript b/chrony.maintscript
new file mode 100644
index 0000000..740a898
--- /dev/null
+++ b/chrony.maintscript
@@ -0,0 +1 @@
+rm_conffile /etc/NetworkManager/dispatcher.d/20-chrony 3.5-7~ chrony
diff --git a/chrony.ppp.ip-down b/chrony.ppp.ip-down
new file mode 100644
index 0000000..c077551
--- /dev/null
+++ b/chrony.ppp.ip-down
@@ -0,0 +1,13 @@
+#!/bin/sh
+# This script tells chronyd that the connection is down
+# so that it won't try to contact the server. 
+# John Hasler <jhasler@debian.org>  1998-2003
+# Any possessor of a copy of this program may treat it as if it
+# were in the public domain.  I waive all rights.
+# Modified by Vincent Blut <vincent.debian@free.fr>
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.ppp.ip-up b/chrony.ppp.ip-up
new file mode 100644
index 0000000..9c8d089
--- /dev/null
+++ b/chrony.ppp.ip-up
@@ -0,0 +1,12 @@
+#!/bin/sh
+# This script tells chronyd that the connection is up so that it can
+# contact the server.  John Hasler <jhasler@debian.org> 1998-2003
+# Any possessor of a copy of this program may treat it as if it
+# were in the public domain.  I waive all rights.
+# Modified by Vincent Blut <vincent.debian@free.fr>
+
+if [ -e /run/chrony/chronyd.pid ]; then
+    chronyc onoffline > /dev/null 2>&1
+fi
+
+exit 0
diff --git a/chrony.service b/chrony.service
new file mode 100644
index 0000000..50d08fa
--- /dev/null
+++ b/chrony.service
@@ -0,0 +1,65 @@
+[Unit]
+Description=chrony, an NTP client/server
+Documentation=man:chronyd(8) man:chronyc(1) man:chrony.conf(5)
+Conflicts=openntpd.service ntp.service ntpsec.service
+Wants=time-sync.target
+Before=time-sync.target
+After=network.target
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/default/chrony
+User=_chrony
+# Daemon is started as root, but still sandboxed
+ExecStart=!/usr/sbin/chronyd $DAEMON_OPTS
+
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD CAP_SYS_ADMIN
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
+DeviceAllow=char-pps rw
+DeviceAllow=char-ptp rw
+DeviceAllow=char-rtc rw
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProcSubset=pid
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+# Used for gps refclocks
+ReadWritePaths=/run
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap
+
+ConfigurationDirectory=chrony
+RuntimeDirectory=chrony
+RuntimeDirectoryMode=0700
+# See dumpdir in chrony.conf(5)
+RuntimeDirectoryPreserve=restart
+StateDirectory=chrony
+StateDirectoryMode=0750
+LogsDirectory=chrony
+LogsDirectoryMode=0750
+
+# Adjust restrictions for /usr/sbin/sendmail (mailonchange directive)
+NoNewPrivileges=no
+ReadWritePaths=-/var/spool
+RestrictAddressFamilies=AF_NETLINK
+
+[Install]
+Alias=chronyd.service
+WantedBy=multi-user.target
diff --git a/clean b/clean
new file mode 100644
index 0000000..70f5857
--- /dev/null
+++ b/clean
@@ -0,0 +1 @@
+getdate.c
diff --git a/conf.d/README b/conf.d/README
new file mode 100644
index 0000000..de1fa8e
--- /dev/null
+++ b/conf.d/README
@@ -0,0 +1,7 @@
+Files found under the /etc/chrony/conf.d directory with the .conf suffix are
+parsed in the lexicographical order of the file names when chronyd starts up.
+This enables a fragmented configuration of chronyd.
+
+Although those files can contain any directives listed in chrony.conf(5),
+it would be wiser to add NTP sources in the /etc/chrony/sources.d
+directory. Please read /etc/chrony/sources.d/README for more information.
diff --git a/control b/control
new file mode 100644
index 0000000..dcafc55
--- /dev/null
+++ b/control
@@ -0,0 +1,54 @@
+Source: chrony
+Section: net
+Priority: optional
+Maintainer: Vincent Blut <vincent.debian@free.fr>
+Standards-Version: 4.6.2
+Build-Depends: asciidoctor,
+               bison,
+               debhelper-compat (= 13),
+               dh-apparmor,
+               gnutls-bin <!nocheck>,
+               iproute2 [linux-any] <!nocheck>,
+               libcap-dev [linux-any],
+               libedit-dev,
+               libgnutls28-dev,
+               libseccomp-dev (>= 2.4.3-1~) [amd64 arm64 armel armhf hppa i386 mips mipsel mips64el powerpc powerpcspe ppc64 ppc64el riscv64 s390x x32],
+               nettle-dev,
+               pkg-config,
+               pps-tools [linux-any],
+               procps <!nocheck>
+Homepage: https://chrony-project.org
+Vcs-Git: https://salsa.debian.org/debian/chrony.git -b debian/latest
+Vcs-Browser: https://salsa.debian.org/debian/chrony
+Rules-Requires-Root: no
+
+Package: chrony
+Architecture: linux-any
+Pre-Depends: ${misc:Pre-Depends}
+Depends: adduser,
+         iproute2 [linux-any],
+         tzdata-legacy,
+         ucf,
+         ${misc:Depends},
+         ${shlibs:Depends}
+Suggests: dnsutils,
+          networkd-dispatcher
+Breaks: network-manager (<< 1.20.0-1~)
+Conflicts: time-daemon
+Provides: time-daemon
+Replaces: time-daemon
+Description: Versatile implementation of the Network Time Protocol
+ It consists of a pair of programs:
+ .
+ chronyd:  This is a daemon which runs in background on the system.
+ It obtains measurements (e.g. via the network) of the system's offset
+ relative to other systems and adjusts the system time accordingly. For
+ isolated systems, the user can periodically enter the correct time by
+ hand (using 'chronyc'). In either case 'chronyd' determines the rate
+ at which the computer gains or loses time, and compensates for this.
+ Chronyd implements the NTP protocol and can act as either a client or
+ a server.
+ .
+ chronyc: This is a command-line driven control and monitoring program.
+ An administrator can use this to fine-tune various parameters within
+ the daemon, add or delete servers etc whilst the daemon is running.
diff --git a/copyright b/copyright
new file mode 100644
index 0000000..ce5b7bd
--- /dev/null
+++ b/copyright
@@ -0,0 +1,187 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Upstream-Name: chrony
+Upstream-Contact: Miroslav Lichvar <mlichvar@redhat.com>
+Source: https://chrony-project.org/releases/
+
+Files: *
+Copyright: 2009-2021, Miroslav Lichvar
+           1997-2007, Richard P. Curnow
+License: GPL-2
+
+Files: main.c
+       sys_linux.c
+Copyright: 2012-2020, Miroslav Lichvar
+           2009, John G. Hasler
+           1997-2003, Richard P. Curnow
+License: GPL-2
+
+Files: ntp_io.c
+Copyright: 2009, 2013-2016, 2018-2021, Miroslav Lichvar
+           2009, Timo Teras
+           1997-2003, Richard P. Curnow
+License: GPL-2
+
+Files: sys_macosx.?
+Copyright: 2015, 2017, 2020, Bryan Christianson
+           2001, J. Hannken-Illjes
+           1997-2001, Richard P. Curnow
+License: GPL-2
+
+Files: sys_netbsd.?
+Copyright: 2001, J. Hannken-Illjes
+           1997-2001, Richard P. Curnow
+License: GPL-2
+
+Files: debian/*
+Copyright: 2015-2023, Vincent Blut
+           2012-2014, Joachim Wiedorn
+           2000-2012, John Hasler
+License: GPL-2
+
+Files: test/simulation/test.common
+Copyright: 2013-2014, Miroslav Lichvar
+License: GPL-2+
+
+Files: privops.c
+Copyright: 2015, Bryan Christianson
+           2017, Miroslav Lichvar
+License: GPL-2
+
+Files: privops.h
+Copyright: 2015, Bryan Christianson
+License: GPL-2
+
+Files: contrib/bryan_christianson_1/chronylogrotate.sh
+Copyright: 2015, Bryan Christianson
+License: GPL-2
+
+Files: test/unit/*
+Copyright: 2016-2023, Miroslav Lichvar
+License: GPL-2
+
+Files: hwclock.?
+Copyright: 2016-2018, 2022, Miroslav Lichvar
+License: GPL-2
+
+Files: ntp_io_linux.?
+Copyright: 2016-2019, 2021-2023 Miroslav Lichvar
+License: GPL-2
+
+Files: ntp_signd.?
+Copyright: 2016, Miroslav Lichvar
+License: GPL-2
+
+Files: client.c
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Lonnie Abelbeck
+           2009-2023, Miroslav Lichvar
+License: GPL-2
+
+Files: configure
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Bryan Christianson
+           2009, 2012-2022, Miroslav Lichvar
+           2019, Stefan R. Filipek
+License: GPL-2
+
+Files: doc/chrony.conf.adoc
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Stephen Wadeley
+           2009-2023, Miroslav Lichvar
+           2017, Bryan Christianson
+License: GPL-2
+
+Files: doc/chronyc.adoc
+Copyright: 1997-2003, Richard P. Curnow
+           2016, Stephen Wadeley
+           2009-2017, 2019-2023, Miroslav Lichvar
+License: GPL-2
+
+Files: refclock.c
+Copyright: 2009-2011, 2013-2014, 2016-2019, 2022 Miroslav Lichvar
+License: GPL-2
+
+Files: refclock_phc.c
+Copyright: 2013, 2017, 2023, Miroslav Lichvar
+License: GPL-2
+
+Files: regress.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011, 2016-2017, Miroslav Lichvar
+License: GPL-2
+
+Files: sched.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011, 2013-2016, Miroslav Lichvar
+License: GPL-2
+
+Files: sourcestats.c
+Copyright: 1997-2003, Richard P. Curnow
+           2011-2014, 2016-2018, 2021, Miroslav Lichvar
+License: GPL-2
+
+Files: stubs.c
+Copyright: 2014-2016, Miroslav Lichvar
+License: GPL-2
+
+Files: hash_nettle.c
+Copyright: 2018, Miroslav Lichvar
+License: GPL-2
+
+Files: test/system/*
+Copyright: 2019, Miroslav Lichvar
+License: GPL-2
+
+Files: md5.*
+Copyright: 1990, RSA Data Security, Inc. All rights reserved.
+License: RSA-MD
+  License to copy and use this software is granted provided that
+  it is identified as the "RSA Data Security, Inc. MD5 Message-
+  Digest Algorithm" in all material mentioning or referencing this
+  software or this function.
+  .
+  License is also granted to make and use derivative works
+  provided that such works are identified as "derived from the RSA
+  Data Security, Inc. MD5 Message-Digest Algorithm" in all
+  material mentioning or referencing the derived work.
+  .
+  RSA Data Security, Inc. makes no representations concerning
+  either the merchantability of this software or the suitability
+  of this software for any particular purpose.  It is provided "as
+  is" without express or implied warranty of any kind.
+  .
+  These notices must be retained in any copies of any part of this
+  documentation and/or software.
+
+License: GPL-2
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License version 2 as
+  published by the Free Software Foundation.
+  .
+  This package is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  .
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+  .
+  On Debian systems, the complete text of the GNU General Public License
+  version 2 can be found in the file `/usr/share/common-licenses/GPL-2'.
+
+License: GPL-2+
+  This package is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+  .
+  This package is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  .
+  You should have received a copy of the GNU General Public License
+  along with this program. If not, see <https://www.gnu.org/licenses/>
+  .
+  On Debian systems, the complete text of the GNU General Public License
+  version 2 can be found in `/usr/share/common-licenses/GPL-2'.
diff --git a/dirs b/dirs
new file mode 100644
index 0000000..152a039
--- /dev/null
+++ b/dirs
@@ -0,0 +1,6 @@
+etc/chrony
+etc/logrotate.d
+etc/ppp/ip-down.d
+etc/ppp/ip-up.d
+usr/lib/NetworkManager/dispatcher.d
+var/lib/chrony
diff --git a/docs b/docs
new file mode 100644
index 0000000..e12f653
--- /dev/null
+++ b/docs
@@ -0,0 +1,3 @@
+FAQ
+NEWS
+README
diff --git a/init b/init
new file mode 100644
index 0000000..ce121d7
--- /dev/null
+++ b/init
@@ -0,0 +1,69 @@
+#! /bin/sh
+#
+# Written by Miquel van Smoorenburg <miquels@drinkel.ow.org>.
+# Modified for Debian GNU/Linux by Ian Murdock <imurdock@gnu.ai.mit.edu>.
+# Modified for Debian by Christoph Lameter <clameter@debian.org>
+# Modified for chrony by John Hasler <jhasler@debian.org> 1998-2012
+# Modified for Debian by Vincent Blut <vincent.debian@free.fr>
+
+### BEGIN INIT INFO
+# Provides:          chrony
+# Required-Start:    $remote_fs
+# Required-Stop:     $remote_fs
+# Should-Start:      $syslog $network $named $time
+# Should-Stop:       $syslog $network $named $time
+# Default-Start:     2 3 4 5
+# Default-Stop:      0 1 6
+# Short-Description: Controls chronyd NTP time daemon
+# Description:       Chronyd is the NTP time daemon in the Chrony package
+### END INIT INFO
+
+PATH=/bin:/usr/bin:/sbin:/usr/sbin
+DAEMON=/usr/sbin/chronyd
+NAME="chronyd"
+DESC="time daemon"
+PIDFILE=/run/chrony/chronyd.pid
+
+[ -x "$DAEMON" ] || exit 0
+
+. /lib/lsb/init-functions
+
+# Override this variable by editing /etc/default/chrony.
+DAEMON_OPTS=""
+if [ -f /etc/default/chrony ]; then
+    . /etc/default/chrony
+fi
+
+case "$1" in
+    start)
+        if $0 status > /dev/null ; then
+            log_success_msg "$NAME is already running"
+        else
+            log_daemon_msg "Starting $DESC" "$NAME"
+            start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $DAEMON -- $DAEMON_OPTS
+            log_end_msg $?
+        fi
+        ;;
+
+    stop)
+        log_daemon_msg "Stopping $DESC" "$NAME"
+        start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE --exec $DAEMON
+        log_end_msg $?
+        ;;
+
+    restart|force-reload)
+        $0 stop
+        $0 start
+        ;;
+
+    status)
+        status_of_proc -p $PIDFILE "$DAEMON" "$NAME" && exit 0 || exit $?
+        ;;
+
+    *)
+        log_action_msg "Usage: /etc/init.d/chrony {start|stop|restart|force-reload|status}"
+        exit 1
+        ;;
+esac
+
+exit 0
diff --git a/install b/install
new file mode 100644
index 0000000..7e730b8
--- /dev/null
+++ b/install
@@ -0,0 +1,9 @@
+debian/chrony-dnssrv@.* lib/systemd/system
+debian/chrony-helper usr/libexec/chrony
+debian/chrony.conf usr/share/chrony
+debian/conf.d etc/chrony
+debian/ntp-units.d/50-chrony.list usr/lib/systemd/ntp-units.d
+debian/sources.d etc/chrony
+debian/usr.sbin.chronyd etc/apparmor.d
+examples/chronyd-restricted.service lib/systemd/system
+examples/chrony-wait.service lib/systemd/system
diff --git a/links b/links
new file mode 100644
index 0000000..31cfb4a
--- /dev/null
+++ b/links
@@ -0,0 +1,5 @@
+# Update sources in response to systemd-networkd events (LP: #1718227).
+# This is reusing the NetworkManager dispatch script which has no hard
+# dependency to NetworkManager (not using any of its arguments)
+usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline usr/lib/networkd-dispatcher/routable.d/chrony-onoffline
+usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline usr/lib/networkd-dispatcher/off.d/chrony-onoffline
diff --git a/ntp-units.d/50-chrony.list b/ntp-units.d/50-chrony.list
new file mode 100644
index 0000000..6b9cca0
--- /dev/null
+++ b/ntp-units.d/50-chrony.list
@@ -0,0 +1 @@
+chrony.service
diff --git a/patches/debianize-chronyd-restricted-unit-file.patch b/patches/debianize-chronyd-restricted-unit-file.patch
new file mode 100644
index 0000000..0560748
--- /dev/null
+++ b/patches/debianize-chronyd-restricted-unit-file.patch
@@ -0,0 +1,24 @@
+Description: Debianize chronyd-restricted.service
+Author: Vincent Blut <vincent.debian@free.fr>
+Forwarded: not-needed
+Last-Update: 2023-08-09
+---
+This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
+Index: chrony/examples/chronyd-restricted.service
+===================================================================
+--- chrony.orig/examples/chronyd-restricted.service
++++ chrony/examples/chronyd-restricted.service
+@@ -14,10 +14,10 @@ ConditionCapability=CAP_SYS_TIME
+ [Service]
+ Type=forking
+ PIDFile=/run/chrony/chronyd.pid
+-EnvironmentFile=-/etc/sysconfig/chronyd
+-ExecStart=/usr/sbin/chronyd -U $OPTIONS
++EnvironmentFile=-/etc/default/chrony
++ExecStart=/usr/sbin/chronyd -U $DAEMON_OPTS
+ 
+-User=chrony
++User=_chrony
+ LogsDirectory=chrony
+ LogsDirectoryMode=0750
+ RuntimeDirectory=chrony
diff --git a/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch b/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
new file mode 100644
index 0000000..2df6629
--- /dev/null
+++ b/patches/nm-dispatcher-dhcp_Move-server_dir-to-run.patch
@@ -0,0 +1,19 @@
+Description: Move server_dir path to /run
+Author: Vincent Blut <vincent.debian@free.fr>
+Forwarded: no
+Last-Update: 2020-09-16
+---
+This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
+Index: chrony/examples/chrony.nm-dispatcher.dhcp
+===================================================================
+--- chrony.orig/examples/chrony.nm-dispatcher.dhcp
++++ chrony/examples/chrony.nm-dispatcher.dhcp
+@@ -10,7 +10,7 @@ action=$2
+ 
+ chronyc=/usr/bin/chronyc
+ server_options=iburst
+-server_dir=/var/run/chrony-dhcp
++server_dir=/run/chrony-dhcp
+ 
+ dhcp_server_file=$server_dir/$interface.sources
+ dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
diff --git a/patches/series b/patches/series
new file mode 100644
index 0000000..23421e3
--- /dev/null
+++ b/patches/series
@@ -0,0 +1,2 @@
+debianize-chronyd-restricted-unit-file.patch
+nm-dispatcher-dhcp_Move-server_dir-to-run.patch
diff --git a/postinst b/postinst
new file mode 100644
index 0000000..1379453
--- /dev/null
+++ b/postinst
@@ -0,0 +1,64 @@
+#!/bin/sh
+# postinst script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+
+# targets: configure|abort-upgrade|abort-remove|abort-deconfigure
+
+case "$1" in
+    configure)
+
+        adduser --system \
+                --group \
+                --quiet \
+                --comment "Chrony daemon" \
+                --home /var/lib/chrony \
+                --no-create-home _chrony
+
+        if command -v ucf >/dev/null
+        then
+            ucf --three-way /usr/share/chrony/chrony.conf /etc/chrony/chrony.conf
+            ucf --three-way /usr/share/chrony/chrony.keys /etc/chrony/chrony.keys
+            if [ -x "$(command -v ucfr)" ]; then
+                ucfr chrony /etc/chrony/chrony.conf
+                ucfr chrony /etc/chrony/chrony.keys
+            fi
+        fi
+
+        # Change the user and group ownership of "/var/l{ib,og}/chrony" iif
+        # the chronyd's configuration does not contain the "user" directive.
+        # Also, update these directories' mode bits to 0750 to follow upstream.
+        #
+        # We must also ensure that chronyd can read /etc/chrony/chrony.keys
+        # after dropping root privileges.
+        if ! chronyd -p | grep -q "^user"; then
+            for d in /var/lib/chrony /var/log/chrony /etc/chrony/chrony.keys; do
+                if ! dpkg-statoverride --list "$d" >/dev/null; then
+                    if [ "$d" = "/etc/chrony/chrony.keys" ]; then
+                        dpkg-statoverride --update --add root _chrony 0640 "$d"
+                    else
+                        dpkg-statoverride --update --add _chrony _chrony 0750 "$d"
+                    fi
+                fi
+            done
+        fi
+    ;;
+
+    abort-upgrade|abort-remove|abort-deconfigure)
+    ;;
+
+    *)
+        echo "postinst called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/postrm b/postrm
new file mode 100644
index 0000000..79713e3
--- /dev/null
+++ b/postrm
@@ -0,0 +1,56 @@
+#!/bin/sh
+# postrm script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# targets: purge|remove|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear
+
+case "$1" in
+    purge)
+        rm -f /var/lib/chrony/*
+        rm -f /etc/chrony/chrony.conf
+        rm -f /etc/chrony/chrony.keys
+        if command -v ucf >/dev/null
+        then
+            ucf --purge /etc/chrony/chrony.conf
+            ucf --purge /etc/chrony/chrony.keys
+            if [ -x "$(command -v ucfr)" ]; then
+                ucfr --purge chrony /etc/chrony/chrony.conf
+                ucfr --purge chrony /etc/chrony/chrony.keys
+            fi
+        fi
+        rm -rf /etc/chrony
+        rm -rf /run/chrony || true
+        rm -rf /run/chrony-dhcp || true
+        rm -rf /var/lib/chrony
+        rm -rf /var/log/chrony
+        # Remove "_chrony" system user/group
+        if [ -x "$(command -v deluser)" ]
+        then
+            deluser --quiet --system _chrony > /dev/null 2>&1 || true
+        fi
+
+        for d in /var/lib/chrony /var/log/chrony /etc/chrony/chrony.keys; do
+            if dpkg-statoverride --list "$d" >/dev/null; then
+                dpkg-statoverride --remove "$d"
+            fi
+        done
+    ;;
+
+    remove|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
+    ;;
+
+    *)
+        echo "postrm called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/prerm b/prerm
new file mode 100644
index 0000000..ec12057
--- /dev/null
+++ b/prerm
@@ -0,0 +1,28 @@
+#!/bin/sh
+# prerm script for chrony
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# targets: remove|upgrade|deconfigure|failed-upgrade
+
+case "$1" in
+    remove|upgrade|deconfigure)
+    ;;
+
+    failed-upgrade)
+    ;;
+
+    *)
+        echo "prerm called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
diff --git a/rules b/rules
new file mode 100755
index 0000000..642abd7
--- /dev/null
+++ b/rules
@@ -0,0 +1,50 @@
+#!/usr/bin/make -f
+
+-include /usr/share/dpkg/buildtools.mk
+export CC
+
+include /usr/share/dpkg/architecture.mk
+
+export DEB_BUILD_MAINT_OPTIONS=hardening=+all
+
+BASE=debian/chrony
+
+%:
+	dh $@
+
+override_dh_auto_configure:
+	dh_auto_configure --  --mandir=/usr/share/man \
+		--sysconfdir=/etc/chrony \
+		--with-user=_chrony \
+		--enable-scfilter \
+		--chronyrundir=/run/chrony \
+		--with-ntp-era=$(shell date -d '1970-01-01 00:00:00+00:00' +'%s') \
+		--enable-ntp-signd \
+		--with-hwclockfile=/etc/adjtime \
+		--with-pidfile=/run/chrony/chronyd.pid \
+		--host-system=Linux
+
+override_dh_install:
+	dh_install
+	install -m 0640 -t $(BASE)/usr/share/chrony/ debian/chrony.keys
+	install -m 0755 -T examples/chrony.nm-dispatcher.dhcp ${BASE}/usr/lib/NetworkManager/dispatcher.d/20-chrony-dhcp
+	install -m 0755 -T examples/chrony.nm-dispatcher.onoffline $(BASE)/usr/lib/NetworkManager/dispatcher.d/20-chrony-onoffline
+	install -m 0644 -T examples/chrony.logrotate $(BASE)/etc/logrotate.d/chrony
+	dh_apparmor --profile-name=usr.sbin.chronyd -pchrony
+	install -D -p -m 0644 debian/chrony.dhcp $(BASE)/etc/dhcp/dhclient-exit-hooks.d/chrony
+
+override_dh_fixperms:
+	dh_fixperms -X usr/share/chrony/chrony.keys
+
+override_dh_installinit:
+	dh_installinit
+# Disable the system call filter on architectures mentioned below
+# due to missing support in libseccomp and/or in the Linux kernel.
+ifneq (,$(filter $(DEB_HOST_ARCH), alpha ia64 m68k sh4 sparc64))
+	sed -i '/DAEMON_OPTS=/s/"-F 1"/""/' $(BASE)/etc/default/chrony
+endif
+
+override_dh_installsystemd:
+	dh_installsystemd chrony.service
+	dh_installsystemd --no-enable --no-start chrony-wait.service
+	dh_installsystemd --no-enable --no-start chronyd-restricted.service
diff --git a/source/format b/source/format
new file mode 100644
index 0000000..163aaf8
--- /dev/null
+++ b/source/format
@@ -0,0 +1 @@
+3.0 (quilt)
diff --git a/sources.d/README b/sources.d/README
new file mode 100644
index 0000000..184eaec
--- /dev/null
+++ b/sources.d/README
@@ -0,0 +1,12 @@
+Only NTP sources can be specified in the /etc/chrony/sources.d directory.
+Files in this directory must end with the ".sources" suffix. They can only
+contain the "peer", "pool" and "server" directives and must have all
+lines terminated by a trailing newline.
+
+There is no need to restart chronyd for these time sources to be usable,
+running 'chronyc reload sources' is sufficient.
+
+Example:
+
+# echo 'server 192.0.2.1 iburst' > /etc/chrony/sources.d/local-ntp-server.sources
+# chronyc reload sources
diff --git a/tests/control b/tests/control
new file mode 100644
index 0000000..98b9106
--- /dev/null
+++ b/tests/control
@@ -0,0 +1,28 @@
+Tests: upstream-simulation-test-suite
+Depends: @builddeps@, build-essential, ca-certificates, tzdata-legacy, wget
+Restrictions: isolation-container, build-needed, skippable, needs-root, needs-internet
+
+Tests: time-sources-from-dhcp-servers
+Depends: @, isc-dhcp-server, isc-dhcp-client, iproute2, kmod
+Restrictions: isolation-machine, needs-root
+
+Features: test-name=run_system_tests
+Test-Command: debian/tests/upstream-system-tests
+Depends: @builddeps@
+Restrictions: build-needed, isolation-container, needs-root
+
+Features: test-name=run_destructive_system_tests
+Test-Command: debian/tests/upstream-system-tests -d 1[0-9][0-9]-*
+Depends: @, @builddeps@, ethtool
+Restrictions: build-needed, isolation-machine, needs-root
+
+Tests: fragmented-configuration
+Restrictions: isolation-container, needs-root
+
+Tests: dynamically-add-source
+Depends: @, dpkg-dev
+Restrictions: isolation-container, needs-root, skippable
+
+Tests: ntp-server-and-nts-auth
+Depends: @, dpkg-dev, gnutls-bin
+Restrictions: isolation-container, needs-root, skippable
diff --git a/tests/dynamically-add-source b/tests/dynamically-add-source
new file mode 100644
index 0000000..1e4c160
--- /dev/null
+++ b/tests/dynamically-add-source
@@ -0,0 +1,27 @@
+#!/bin/sh
+# Make sure that NTP sources from /etc/chrony/sources.d are usable.
+
+set -e
+
+. debian/tests/helper-functions
+
+server_addr="192.0.2.1"
+
+printf "Preparing chronyd configuration: "
+__no_system_clock_control
+__restart_chronyd && __test_ok || __test_skip
+
+printf "Adding a dummy server to the list of NTP sources: "
+printf "server $server_addr\n" > /etc/chrony/sources.d/dummy-server.sources && __test_ok || __test_fail
+
+printf "Reloading NTP sources: "
+__reload_sources
+
+printf "Checking for dummy server availability: "
+__check_sources "$server_addr"
+
+printf "Checking for dummy server availability after restarting chronyd: "
+__restart_chronyd
+__check_sources "$server_addr"
+
+exit 0
diff --git a/tests/fragmented-configuration b/tests/fragmented-configuration
new file mode 100644
index 0000000..2135df3
--- /dev/null
+++ b/tests/fragmented-configuration
@@ -0,0 +1,17 @@
+#!/bin/sh
+# Make sure that fragmented configuration works as expected.
+
+set -e
+
+. debian/tests/helper-functions
+
+printf 'Setting "authselectmode prefer" as authentication policy: '
+echo "authselectmode prefer" > /etc/chrony/conf.d/authentication-policy.conf && __test_ok || __test_fail
+
+printf "Restart chronyd: "
+systemctl --quiet restart chrony.service && __test_ok || __test_fail
+
+printf "Checking that chronyd uses the defined authentication policy: "
+chronyd -p | grep -q "authselectmode prefer" && __test_ok || __test_fail
+
+exit 0
diff --git a/tests/helper-functions b/tests/helper-functions
new file mode 100644
index 0000000..7df6ee9
--- /dev/null
+++ b/tests/helper-functions
@@ -0,0 +1,53 @@
+__no_system_clock_control() {
+    if ! dpkg-vendor --derives-from Ubuntu; then
+        sed -i '/^DAEMON_OPTS=/s/"\(.*\)"/"\1 -x"/' /etc/default/chrony
+        mkdir -p /etc/systemd/system/chrony.service.d
+        cat <<EOF > /etc/systemd/system/chrony.service.d/override.conf
+[Unit]
+ConditionCapability=
+EOF
+        systemctl daemon-reload
+    fi
+}
+
+__test_fail() {
+    printf 'FAIL\n' >&2
+    return 1
+}
+
+__test_ok() {
+    printf 'OK\n'
+    return 0
+}
+
+__test_skip() {
+    [ -n "$1" ] && printf 'SKIP: (%s)\n' "$1" || printf 'SKIP\n'
+    exit 77
+}
+
+__reload_sources() {
+    chronyc reload sources > /dev/null 2>&1 && __test_ok || __test_fail
+}
+
+__restart_chronyd() {
+    systemctl --quiet restart chrony.service
+    rc=$?
+    sleep 3
+    return $rc
+}
+
+__check_sources() {
+    chronyc sources | grep -q "$1" && __test_ok || __test_fail
+}
+
+__check_auth() {
+    chronyc -c authdata | grep -q "$1" && __test_ok || __test_fail
+}
+
+# Ubuntu's default config is fully populated causing issues with the test
+# If any of those tests run on Ubuntu, clear some and restart the daemon
+# to pick this up before entering the tests.
+if grep -q "^pool.*ubuntu.pool.ntp.org" /etc/chrony/chrony.conf; then
+    sudo sed -i -e '/^pool.*ubuntu.pool.ntp.org/d' /etc/chrony/chrony.conf
+    __restart_chronyd
+fi
diff --git a/tests/ntp-server-and-nts-auth b/tests/ntp-server-and-nts-auth
new file mode 100644
index 0000000..b7d8877
--- /dev/null
+++ b/tests/ntp-server-and-nts-auth
@@ -0,0 +1,59 @@
+#!/bin/sh
+# Check that chronyd is able to authenticate NTP packets when NTS is enabled
+# on the server.
+
+set -e
+
+. debian/tests/helper-functions
+
+cert_dir="/var/lib/chrony"
+cert_template="$cert_dir/cert.cfg"
+cert_file="$cert_dir/server.crt"
+priv_key="$cert_dir/server.key"
+server_addr="127.0.1.1"
+server_name="chrony-nts-test"
+
+create_cert_template() {
+    printf "Creating certificate template: "
+    cat <<EOF > "$cert_template"
+cn = "$server_name"
+serial = 001
+activation_date = "$(date -d '1 year ago' +'%Y-%m-%d') 00:00:00 UTC"
+expiration_date = "$(date -d '1 year' +'%Y-%m-%d') 00:00:00 UTC"
+signing_key
+encryption_key
+EOF
+}
+
+generate_cert() {
+    printf "Generating self-signed certificate: "
+    certtool --generate-privkey --key-type=ed25519 --outfile "$priv_key" > /dev/null 2>&1
+    certtool --generate-self-signed --load-privkey "$priv_key" --template "$cert_template" \
+        --outfile "$cert_file" > /dev/null 2>&1
+}
+
+server_config() {
+    printf "Preparing chronyd configuration: "
+    cat <<EOF > /etc/chrony/conf.d/local-server-config.conf
+server $server_name nts minpoll -6 maxpoll -6
+ntsserverkey $priv_key
+ntsservercert $cert_file
+ntstrustedcerts $cert_file
+EOF
+
+    __no_system_clock_control
+    __restart_chronyd
+}
+
+echo "$server_addr $server_name" >> /etc/hosts
+
+create_cert_template && __test_ok || __test_skip "unable to create certificate template"
+
+generate_cert && __test_ok || __test_skip "unable to generate self-signed certificate"
+
+server_config && __test_ok || __test_skip
+
+printf "Checking if server authenticates NTP packets: "
+__check_auth "$server_addr,NTS"
+
+exit 0
diff --git a/tests/time-sources-from-dhcp-servers b/tests/time-sources-from-dhcp-servers
new file mode 100644
index 0000000..f5e7899
--- /dev/null
+++ b/tests/time-sources-from-dhcp-servers
@@ -0,0 +1,44 @@
+#!/bin/sh
+# Ensure that NTP servers obtained from DHCP are made available to chronyd and
+# that they are removed when releasing the DHCP lease.
+
+set -e
+
+prepare_iface() {
+    modprobe dummy
+    ip link add name dummy0 type dummy
+    ip address add 192.168.1.1/24 dev dummy0
+    ip link set dev dummy0 up
+}
+
+dhcpd_config() {
+cat <<EOF > /etc/dhcp/dhcpd.conf
+default-lease-time 600;
+max-lease-time 7200;
+authorative;
+
+subnet 192.168.1.0 netmask 255.255.255.0 {
+    option subnet-mask              255.255.255.0;
+    option broadcast-address        192.168.1.255;
+    option ntp-servers              192.168.1.50;
+    range 192.168.1.42 192.168.1.100;
+}
+EOF
+
+sed -i '/INTERFACESv4=/s/".*"/"dummy0"/' /etc/default/isc-dhcp-server
+}
+
+chk_time_src() {
+    chronyc -n sources | grep -q -F '192.168.1.50'
+}
+
+printf "Preparing the dummy network interface and dhcpd configuration…\n"
+if prepare_iface && dhcpd_config; then
+    systemctl restart isc-dhcp-server && dhclient dummy0 && printf "Done!\n\n"
+fi
+
+printf "Check if the NTP server is made available to chronyd…\n"
+chk_time_src && printf "SUCCESS!\n\n"
+
+printf "Release the current lease and check if the NTP server has been correctly removed…\n"
+dhclient -r dummy0 > /dev/null 2>&1 && ! chk_time_src && printf "SUCCESS!\n\n"
diff --git a/tests/upstream-simulation-test-suite b/tests/upstream-simulation-test-suite
new file mode 100644
index 0000000..958aed5
--- /dev/null
+++ b/tests/upstream-simulation-test-suite
@@ -0,0 +1,41 @@
+#!/bin/sh
+# Upstream makes use of “clknetsim” to test how well “chronyd” controls the
+# system clocks in various conditions. Due to “clknetsim” not being available
+# in Debian, let’s use autopkgtest facility to build it in a container and
+# test “chronyd” from there.
+
+set -e
+
+testdir="$PWD/test/simulation"
+clknetsim_ver=ef2a7a9
+clknetsim_src=https://github.com/mlichvar/clknetsim/archive/"$clknetsim_ver"/clknetsim-"$clknetsim_ver".tar.gz
+clknetsim_archive=$(basename "$clknetsim_src")
+
+export CLKNETSIM_PATH="$AUTOPKGTEST_TMP"
+
+# Always use the same seed to get deterministic results
+export CLKNETSIM_RANDOM_SEED=24508
+
+DEB_HOST_MULTIARCH=$(dpkg-architecture -qDEB_HOST_MULTIARCH)
+
+# The simulation tests are only supported on Linux.
+dpkg-architecture -ilinux-any || exit 77
+
+prepare_clknetsim() {
+    # This symbolic link is necessary to prevent clknetsim from FTBFS.
+    ln -s /usr/include/"$DEB_HOST_MULTIARCH"/sys/time.h /usr/include/sys/
+
+    wget -P "$CLKNETSIM_PATH" "$clknetsim_src" 2>&1 || exit 77
+    tar -xvzf "$CLKNETSIM_PATH"/"$clknetsim_archive" \
+        -C "$CLKNETSIM_PATH" --strip-components=1 2>&1 || exit 77
+
+    if [ ! -x "$CLKNETSIM_PATH/clknetsim" ] && [ ! -e "$CLKNETSIM_PATH/clknetsim.so" ]; then
+        make -C "$CLKNETSIM_PATH" 2>&1
+    fi
+}
+
+run_test() {
+    cd "$testdir" && ./run
+}
+
+prepare_clknetsim && run_test
diff --git a/tests/upstream-system-tests b/tests/upstream-system-tests
new file mode 100755
index 0000000..bd28a0c
--- /dev/null
+++ b/tests/upstream-system-tests
@@ -0,0 +1,24 @@
+#!/bin/sh
+# Run the upstream system tests in a container. Destructive tests will be run in
+# a VM as they may adjust/step the system clock, block the RTC, etc.
+# In case of failure, test’s logs will be put into the directory specified by
+# the $AUTOPKGTEST_ARTIFACTS environment variable.
+
+set -e
+
+testdir=$PWD/test/system
+logdir="$testdir/tmp/*"
+
+# some tests need chrony installed, but make sure to avoid the test daemon is
+# fighting with the systems chrony service over the clock
+systemctl stop chrony.service 2>/dev/null || true
+
+run_test() {
+     cd "$testdir" && ./run "$@"
+}
+
+artifacts() {
+    cp $logdir "$AUTOPKGTEST_ARTIFACTS" && exit 1
+}
+
+run_test "$@" || artifacts
diff --git a/upstream/metadata b/upstream/metadata
new file mode 100644
index 0000000..8a19a1d
--- /dev/null
+++ b/upstream/metadata
@@ -0,0 +1,8 @@
+Documentation: https://chrony-project.org/documentation.html
+Changelog: https://chrony-project.org/news.html
+FAQ: https://chrony-project.org/faq.html
+Contact: chrony-users@chrony.tuxfamily.org
+Security-Contact: Miroslav Lichvar <mlichvar@redhat.com>
+Bug-Submit: chrony-users@chrony.tuxfamily.org
+Repository: https://gitlab.com/chrony/chrony.git
+Repository-Browse: https://gitlab.com/chrony/chrony
diff --git a/upstream/signing-key.asc b/upstream/signing-key.asc
new file mode 100644
index 0000000..e12834f
--- /dev/null
+++ b/upstream/signing-key.asc
@@ -0,0 +1,52 @@
+-----BEGIN PGP PUBLIC KEY BLOCK-----
+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+W23ALtrl30a0MaWqnDo=
+=kLnA
+-----END PGP PUBLIC KEY BLOCK-----
diff --git a/usr.sbin.chronyd b/usr.sbin.chronyd
new file mode 100644
index 0000000..bc52d4f
--- /dev/null
+++ b/usr.sbin.chronyd
@@ -0,0 +1,85 @@
+# vim:syntax=apparmor
+# Last Modified: Sun Sep 05 16:48:05 2021
+
+abi <abi/3.0>,
+
+#include <tunables/global>
+
+/usr/sbin/chronyd flags=(attach_disconnected) {
+  #include <abstractions/base>
+  #include <abstractions/nameservice>
+
+  # For /run/chrony to be created
+  capability chown,
+
+  # Give “root” the ability to read and write the PID file
+  capability dac_override,
+  capability dac_read_search,
+
+  # Needed to support HW timestamping
+  capability net_admin,
+
+  # Needed to allow NTP server sockets to be bound to a privileged port
+  capability net_bind_service,
+
+  # Needed to allow an NTP socket to be bound to a device using the
+  # SO_BINDTODEVICE socket option on kernels before 5.7
+  capability net_raw,
+
+  # Needed to drop privileges
+  capability setgid,
+  capability setuid,
+
+  # Needed to set the SCHED_FIFO real-time scheduler at the specified priority
+  # using the '-P' option
+  capability sys_nice,
+
+  # Needed to lock chronyd into RAM
+  capability sys_resource,
+
+  # Needed to set the system/real-time clock
+  capability sys_time,
+
+  /usr/sbin/chronyd mr,
+
+  /etc/chrony/{,**} r,
+  /var/lib/chrony/{,*} rw,
+  /var/log/chrony/{,*} rw,
+  @{run}/chrony/{,*} rw,
+  @{run}/chrony-dhcp/{,*} r,
+
+  # Using the “tempcomp” directive gives chronyd the ability to improve
+  # the stability and accuracy of the clock by compensating the temperature
+  # changes measured by a sensor close to the oscillator.
+  @{sys}/class/hwmon/hwmon[0-9]*/temp[0-9]*_input r,
+  @{sys}/devices/virtual/thermal/thermal_zone[0-9]*/hwmon[0-9]*/temp[0-9]*_input r,
+
+  # Support all paths suggested in the man page (LP: #1771028). Assume these
+  # are common use cases; others should be set as local include (see below).
+  # Configs using a 'chrony.' prefix like the tempcomp config file example
+  /etc/chrony.* r,
+  # Example gpsd socket is outside @{run}/chrony/
+  @{run}/chrony.*.sock rw,
+  # To sign replies to MS-SNTP clients by the smbd daemon
+  /var/lib/samba/ntp_signd/socket rw,
+
+  # rtc
+  /etc/adjtime r,
+  /dev/rtc{,[0-9]*} rw,
+
+  # gps devices
+  /dev/pps[0-9]* rw,
+  /dev/ptp[0-9]* rw,
+
+  # Allow reading the chronyd configuration file that timemaster(8) generates
+  @{run}/timemaster/chrony.conf r,
+
+  # For use with clocks that report via shared memory (e.g. gpsd),
+  # you may need to give ntpd access to all of shared memory, though
+  # this can be considered dangerous. See https://launchpad.net/bugs/722815
+  # for details. To enable, add this to local/usr.sbin.chronyd:
+  #     capability ipc_owner,
+
+  # Site-specific additions and overrides. See local/README for details.
+  #include <local/usr.sbin.chronyd>
+}
diff --git a/watch b/watch
new file mode 100644
index 0000000..0a64136
--- /dev/null
+++ b/watch
@@ -0,0 +1,3 @@
+version=4
+opts="pgpsigurlmangle=s/\.tar\.gz$/-tar-gz-asc.txt/,uversionmangle=s/-pre/~pre/" \
+https://chrony-project.org/releases/@PACKAGE@@ANY_VERSION@@ARCHIVE_EXT@
-- 
cgit v1.2.3


From 3df86e9f82da6a0ea967270dc6b6ff871eb04071 Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 9 Aug 2023 17:50:42 +0200
Subject: Import chrony_4.4.orig.tar.gz

[dgit import orig chrony_4.4.orig.tar.gz]
---
 COPYING                                            |  339 ++
 FAQ                                                | 1095 +++++
 INSTALL                                            |  165 +
 Makefile.in                                        |  143 +
 NEWS                                               | 1003 ++++
 README                                             |  140 +
 addressing.h                                       |   67 +
 addrfilt.c                                         |  405 ++
 addrfilt.h                                         |   80 +
 array.c                                            |  145 +
 array.h                                            |   59 +
 candm.h                                            |  849 ++++
 client.c                                           | 3535 ++++++++++++++
 clientlog.c                                        | 1111 +++++
 clientlog.h                                        |   67 +
 cmac.h                                             |   48 +
 cmac_gnutls.c                                      |  189 +
 cmac_nettle.c                                      |  117 +
 cmdmon.c                                           | 1869 ++++++++
 cmdmon.h                                           |   40 +
 cmdparse.c                                         |  425 ++
 cmdparse.h                                         |   63 +
 conf.c                                             | 2645 +++++++++++
 conf.h                                             |  176 +
 configure                                          | 1154 +++++
 contrib/andrew_bishop_1                            |  114 +
 contrib/andrew_bishop_2                            |   95 +
 contrib/bryan_christianson_1/README.txt            |  103 +
 contrib/bryan_christianson_1/chronylogrotate.sh    |   58 +
 .../org.chrony-project.chronyc.plist               |   22 +
 .../org.chrony-project.chronyd.plist               |   19 +
 contrib/erik_bryer_1                               |   65 +
 contrib/ken_gillett_1                              |  100 +
 contrib/stephan_boettcher_1                        |  162 +
 contrib/wolfgang_weisselberg1                      |  118 +
 doc/Makefile.in                                    |   76 +
 doc/chrony.conf.adoc                               | 3144 ++++++++++++
 doc/chrony.conf.man.in                             | 5024 ++++++++++++++++++++
 doc/chronyc.adoc                                   | 1555 ++++++
 doc/chronyc.man.in                                 | 2752 +++++++++++
 doc/chronyd.adoc                                   |  224 +
 doc/chronyd.man.in                                 |  266 ++
 doc/faq.adoc                                       | 1103 +++++
 doc/installation.adoc                              |  200 +
 examples/chrony-wait.service                       |   46 +
 examples/chrony.conf.example1                      |   12 +
 examples/chrony.conf.example2                      |   47 +
 examples/chrony.conf.example3                      |  334 ++
 examples/chrony.keys.example                       |   15 +
 examples/chrony.logrotate                          |    8 +
 examples/chrony.nm-dispatcher.dhcp                 |   49 +
 examples/chrony.nm-dispatcher.onoffline            |   29 +
 examples/chronyd-restricted.service                |   58 +
 examples/chronyd.service                           |   48 +
 getdate.c                                          | 2601 ++++++++++
 getdate.h                                          |   28 +
 getdate.y                                          | 1039 ++++
 hash.h                                             |   57 +
 hash_gnutls.c                                      |  145 +
 hash_intmd5.c                                      |   71 +
 hash_nettle.c                                      |  124 +
 hash_nss.c                                         |  114 +
 hash_tomcrypt.c                                    |  126 +
 hwclock.c                                          |  334 ++
 hwclock.h                                          |   54 +
 keys.c                                             |  441 ++
 keys.h                                             |   47 +
 local.c                                            |  781 +++
 local.h                                            |  229 +
 localp.h                                           |   74 +
 logging.c                                          |  381 ++
 logging.h                                          |  143 +
 main.c                                             |  703 +++
 main.h                                             |   35 +
 manual.c                                           |  332 ++
 manual.h                                           |   46 +
 md5.c                                              |  315 ++
 md5.h                                              |   56 +
 memory.c                                           |   98 +
 memory.h                                           |   45 +
 nameserv.c                                         |  166 +
 nameserv.h                                         |   52 +
 nameserv_async.c                                   |  130 +
 nameserv_async.h                                   |   40 +
 ntp.h                                              |  189 +
 ntp_auth.c                                         |  386 ++
 ntp_auth.h                                         |   84 +
 ntp_core.c                                         | 3142 ++++++++++++
 ntp_core.h                                         |  138 +
 ntp_ext.c                                          |  192 +
 ntp_ext.h                                          |   43 +
 ntp_io.c                                           |  623 +++
 ntp_io.h                                           |   73 +
 ntp_io_linux.c                                     |  810 ++++
 ntp_io_linux.h                                     |   45 +
 ntp_signd.c                                        |  341 ++
 ntp_signd.h                                        |   42 +
 ntp_sources.c                                      | 1536 ++++++
 ntp_sources.h                                      |  152 +
 nts_ke.h                                           |   81 +
 nts_ke_client.c                                    |  457 ++
 nts_ke_client.h                                    |   56 +
 nts_ke_server.c                                    | 1034 ++++
 nts_ke_server.h                                    |   49 +
 nts_ke_session.c                                   |  929 ++++
 nts_ke_session.h                                   |   93 +
 nts_ntp.h                                          |   36 +
 nts_ntp_auth.c                                     |  187 +
 nts_ntp_auth.h                                     |   43 +
 nts_ntp_client.c                                   |  717 +++
 nts_ntp_client.h                                   |   51 +
 nts_ntp_server.c                                   |  309 ++
 nts_ntp_server.h                                   |   40 +
 pktlength.c                                        |  222 +
 pktlength.h                                        |   40 +
 privops.c                                          |  696 +++
 privops.h                                          |   77 +
 ptp.h                                              |   69 +
 quantiles.c                                        |  209 +
 quantiles.h                                        |   41 +
 refclock.c                                         |  862 ++++
 refclock.h                                         |   86 +
 refclock_phc.c                                     |  232 +
 refclock_pps.c                                     |  159 +
 refclock_shm.c                                     |  134 +
 refclock_sock.c                                    |  176 +
 reference.c                                        | 1441 ++++++
 reference.h                                        |  200 +
 regress.c                                          |  704 +++
 regress.h                                          |  137 +
 reports.h                                          |  212 +
 rtc.c                                              |  242 +
 rtc.h                                              |   45 +
 rtc_linux.c                                        | 1072 +++++
 rtc_linux.h                                        |   45 +
 samplefilt.c                                       |  497 ++
 samplefilt.h                                       |   51 +
 sched.c                                            |  866 ++++
 sched.h                                            |   93 +
 siv.h                                              |   74 +
 siv_gnutls.c                                       |  287 ++
 siv_nettle.c                                       |  251 +
 siv_nettle_int.c                                   |  452 ++
 smooth.c                                           |  370 ++
 smooth.h                                           |   48 +
 socket.c                                           | 1648 +++++++
 socket.h                                           |  147 +
 sources.c                                          | 1854 ++++++++
 sources.h                                          |  144 +
 sourcestats.c                                      | 1041 ++++
 sourcestats.h                                      |  141 +
 srcparams.h                                        |   93 +
 stubs.c                                            |  567 +++
 sys.c                                              |  150 +
 sys.h                                              |   53 +
 sys_generic.c                                      |  449 ++
 sys_generic.h                                      |   46 +
 sys_linux.c                                        | 1025 ++++
 sys_linux.h                                        |   52 +
 sys_macosx.c                                       |  516 ++
 sys_macosx.h                                       |   40 +
 sys_netbsd.c                                       |  158 +
 sys_netbsd.h                                       |   39 +
 sys_null.c                                         |  140 +
 sys_null.h                                         |   34 +
 sys_posix.c                                        |  109 +
 sys_posix.h                                        |   36 +
 sys_solaris.c                                      |   95 +
 sys_solaris.h                                      |   38 +
 sys_timex.c                                        |  276 ++
 sys_timex.h                                        |   48 +
 sysincl.h                                          |   69 +
 tempcomp.c                                         |  176 +
 tempcomp.h                                         |   29 +
 test/compilation/001-features                      |   36 +
 test/compilation/002-scanbuild                     |   16 +
 test/compilation/003-sanitizers                    |  104 +
 test/kernel/Makefile                               |    7 +
 test/kernel/adjtime.c                              |  185 +
 test/kernel/ntpadjtime.c                           |   75 +
 test/simulation/001-defaults                       |   13 +
 test/simulation/002-largenetwork                   |   22 +
 test/simulation/003-largefreqoffset                |   19 +
 test/simulation/004-largetimeoffset                |   18 +
 test/simulation/005-externalstep                   |   46 +
 test/simulation/006-largejitter                    |   21 +
 test/simulation/007-largewander                    |   20 +
 test/simulation/008-ntpera                         |   50 +
 test/simulation/009-sourceselection                |   40 +
 test/simulation/010-multrecv                       |   17 +
 test/simulation/011-asymjitter                     |   18 +
 test/simulation/012-daemonts                       |   15 +
 test/simulation/013-nameserv                       |   15 +
 test/simulation/101-poll                           |   56 +
 test/simulation/102-iburst                         |   23 +
 test/simulation/103-initstepslew                   |   63 +
 test/simulation/104-driftfile                      |   23 +
 test/simulation/105-ntpauth                        |   96 +
 test/simulation/106-refclock                       |  143 +
 test/simulation/107-allowdeny                      |   48 +
 test/simulation/108-peer                           |   54 +
 test/simulation/109-makestep                       |   41 +
 test/simulation/110-chronyc                        |  529 +++
 test/simulation/111-knownclient                    |   17 +
 test/simulation/112-port                           |   57 +
 test/simulation/113-leapsecond                     |   61 +
 test/simulation/114-presend                        |   26 +
 test/simulation/115-cmdmontime                     |   24 +
 test/simulation/116-minsources                     |   24 +
 test/simulation/117-fallbackdrift                  |   24 +
 test/simulation/118-maxdelay                       |   42 +
 test/simulation/119-smoothtime                     |   82 +
 test/simulation/120-selectoptions                  |   89 +
 test/simulation/121-orphan                         |   26 +
 test/simulation/122-xleave                         |   91 +
 test/simulation/123-mindelay                       |   27 +
 test/simulation/124-tai                            |   45 +
 test/simulation/125-packetloss                     |   29 +
 test/simulation/126-burst                          |   45 +
 test/simulation/127-filter                         |   43 +
 test/simulation/128-nocontrol                      |   27 +
 test/simulation/129-reload                         |  109 +
 test/simulation/130-quit                           |   31 +
 test/simulation/131-maxchange                      |   20 +
 test/simulation/132-logchange                      |   21 +
 test/simulation/133-hwtimestamp                    |   89 +
 test/simulation/134-log                            |   35 +
 test/simulation/135-ratelimit                      |   18 +
 test/simulation/136-broadcast                      |   16 +
 test/simulation/137-pool                           |   49 +
 test/simulation/138-syncloop                       |   34 +
 test/simulation/139-nts                            |  316 ++
 test/simulation/140-noclientlog                    |   21 +
 test/simulation/141-copy                           |   19 +
 test/simulation/142-ptpport                        |   41 +
 test/simulation/143-manual                         |   70 +
 test/simulation/144-exp1                           |   55 +
 test/simulation/145-rtc                            |   75 +
 test/simulation/146-offline                        |   73 +
 test/simulation/147-refresh                        |   59 +
 test/simulation/148-replacement                    |   56 +
 test/simulation/201-freqaccumulation               |   35 +
 test/simulation/202-prefer                         |   21 +
 test/simulation/README                             |   11 +
 test/simulation/run                                |   90 +
 test/simulation/test.common                        |  534 +++
 test/system/001-minimal                            |   13 +
 test/system/002-extended                           |   13 +
 test/system/003-memlock                            |   15 +
 test/system/004-priority                           |   15 +
 test/system/006-privdrop                           |   17 +
 test/system/007-cmdmon                             |  188 +
 test/system/008-confload                           |   74 +
 test/system/009-binddevice                         |   24 +
 test/system/010-nts                                |   66 +
 test/system/099-scfilter                           |   24 +
 test/system/100-clockupdate                        |   30 +
 test/system/101-rtc                                |   19 +
 test/system/102-hwtimestamp                        |   28 +
 test/system/103-refclock                           |   19 +
 test/system/104-systemdirs                         |   19 +
 test/system/199-scfilter                           |   24 +
 test/system/run                                    |   64 +
 test/system/test.common                            |  375 ++
 test/unit/Makefile.in                              |   48 +
 test/unit/addrfilt.c                               |   83 +
 test/unit/array.c                                  |   97 +
 test/unit/clientlog.c                              |  298 ++
 test/unit/cmac.c                                   |  109 +
 test/unit/hash.c                                   |  131 +
 test/unit/hwclock.c                                |  117 +
 test/unit/keys.c                                   |  173 +
 test/unit/ntp_auth.c                               |  289 ++
 test/unit/ntp_core.c                               |  648 +++
 test/unit/ntp_core.keys                            |    8 +
 test/unit/ntp_ext.c                                |  167 +
 test/unit/ntp_sources.c                            |  376 ++
 test/unit/nts_ke.crt                               |    8 +
 test/unit/nts_ke.key                               |   25 +
 test/unit/nts_ke_client.c                          |  147 +
 test/unit/nts_ke_server.c                          |  235 +
 test/unit/nts_ke_session.c                         |  224 +
 test/unit/nts_ntp_auth.c                           |  135 +
 test/unit/nts_ntp_client.c                         |  302 ++
 test/unit/nts_ntp_server.c                         |  180 +
 test/unit/quantiles.c                              |   68 +
 test/unit/regress.c                                |  119 +
 test/unit/samplefilt.c                             |  120 +
 test/unit/siv.c                                    |  423 ++
 test/unit/smooth.c                                 |   63 +
 test/unit/sources.c                                |  289 ++
 test/unit/test.c                                   |  182 +
 test/unit/test.h                                   |   52 +
 test/unit/util.c                                   |  760 +++
 util.c                                             | 1623 +++++++
 util.h                                             |  271 ++
 version.txt                                        |    1 +
 297 files changed, 85051 insertions(+)
 create mode 100644 COPYING
 create mode 100644 FAQ
 create mode 100644 INSTALL
 create mode 100644 Makefile.in
 create mode 100644 NEWS
 create mode 100644 README
 create mode 100644 addressing.h
 create mode 100644 addrfilt.c
 create mode 100644 addrfilt.h
 create mode 100644 array.c
 create mode 100644 array.h
 create mode 100644 candm.h
 create mode 100644 client.c
 create mode 100644 clientlog.c
 create mode 100644 clientlog.h
 create mode 100644 cmac.h
 create mode 100644 cmac_gnutls.c
 create mode 100644 cmac_nettle.c
 create mode 100644 cmdmon.c
 create mode 100644 cmdmon.h
 create mode 100644 cmdparse.c
 create mode 100644 cmdparse.h
 create mode 100644 conf.c
 create mode 100644 conf.h
 create mode 100755 configure
 create mode 100644 contrib/andrew_bishop_1
 create mode 100644 contrib/andrew_bishop_2
 create mode 100644 contrib/bryan_christianson_1/README.txt
 create mode 100755 contrib/bryan_christianson_1/chronylogrotate.sh
 create mode 100644 contrib/bryan_christianson_1/org.chrony-project.chronyc.plist
 create mode 100644 contrib/bryan_christianson_1/org.chrony-project.chronyd.plist
 create mode 100644 contrib/erik_bryer_1
 create mode 100644 contrib/ken_gillett_1
 create mode 100644 contrib/stephan_boettcher_1
 create mode 100644 contrib/wolfgang_weisselberg1
 create mode 100644 doc/Makefile.in
 create mode 100644 doc/chrony.conf.adoc
 create mode 100644 doc/chrony.conf.man.in
 create mode 100644 doc/chronyc.adoc
 create mode 100644 doc/chronyc.man.in
 create mode 100644 doc/chronyd.adoc
 create mode 100644 doc/chronyd.man.in
 create mode 100644 doc/faq.adoc
 create mode 100644 doc/installation.adoc
 create mode 100644 examples/chrony-wait.service
 create mode 100644 examples/chrony.conf.example1
 create mode 100644 examples/chrony.conf.example2
 create mode 100644 examples/chrony.conf.example3
 create mode 100644 examples/chrony.keys.example
 create mode 100644 examples/chrony.logrotate
 create mode 100644 examples/chrony.nm-dispatcher.dhcp
 create mode 100644 examples/chrony.nm-dispatcher.onoffline
 create mode 100644 examples/chronyd-restricted.service
 create mode 100644 examples/chronyd.service
 create mode 100644 getdate.c
 create mode 100644 getdate.h
 create mode 100644 getdate.y
 create mode 100644 hash.h
 create mode 100644 hash_gnutls.c
 create mode 100644 hash_intmd5.c
 create mode 100644 hash_nettle.c
 create mode 100644 hash_nss.c
 create mode 100644 hash_tomcrypt.c
 create mode 100644 hwclock.c
 create mode 100644 hwclock.h
 create mode 100644 keys.c
 create mode 100644 keys.h
 create mode 100644 local.c
 create mode 100644 local.h
 create mode 100644 localp.h
 create mode 100644 logging.c
 create mode 100644 logging.h
 create mode 100644 main.c
 create mode 100644 main.h
 create mode 100644 manual.c
 create mode 100644 manual.h
 create mode 100644 md5.c
 create mode 100644 md5.h
 create mode 100644 memory.c
 create mode 100644 memory.h
 create mode 100644 nameserv.c
 create mode 100644 nameserv.h
 create mode 100644 nameserv_async.c
 create mode 100644 nameserv_async.h
 create mode 100644 ntp.h
 create mode 100644 ntp_auth.c
 create mode 100644 ntp_auth.h
 create mode 100644 ntp_core.c
 create mode 100644 ntp_core.h
 create mode 100644 ntp_ext.c
 create mode 100644 ntp_ext.h
 create mode 100644 ntp_io.c
 create mode 100644 ntp_io.h
 create mode 100644 ntp_io_linux.c
 create mode 100644 ntp_io_linux.h
 create mode 100644 ntp_signd.c
 create mode 100644 ntp_signd.h
 create mode 100644 ntp_sources.c
 create mode 100644 ntp_sources.h
 create mode 100644 nts_ke.h
 create mode 100644 nts_ke_client.c
 create mode 100644 nts_ke_client.h
 create mode 100644 nts_ke_server.c
 create mode 100644 nts_ke_server.h
 create mode 100644 nts_ke_session.c
 create mode 100644 nts_ke_session.h
 create mode 100644 nts_ntp.h
 create mode 100644 nts_ntp_auth.c
 create mode 100644 nts_ntp_auth.h
 create mode 100644 nts_ntp_client.c
 create mode 100644 nts_ntp_client.h
 create mode 100644 nts_ntp_server.c
 create mode 100644 nts_ntp_server.h
 create mode 100644 pktlength.c
 create mode 100644 pktlength.h
 create mode 100644 privops.c
 create mode 100644 privops.h
 create mode 100644 ptp.h
 create mode 100644 quantiles.c
 create mode 100644 quantiles.h
 create mode 100644 refclock.c
 create mode 100644 refclock.h
 create mode 100644 refclock_phc.c
 create mode 100644 refclock_pps.c
 create mode 100644 refclock_shm.c
 create mode 100644 refclock_sock.c
 create mode 100644 reference.c
 create mode 100644 reference.h
 create mode 100644 regress.c
 create mode 100644 regress.h
 create mode 100644 reports.h
 create mode 100644 rtc.c
 create mode 100644 rtc.h
 create mode 100644 rtc_linux.c
 create mode 100644 rtc_linux.h
 create mode 100644 samplefilt.c
 create mode 100644 samplefilt.h
 create mode 100644 sched.c
 create mode 100644 sched.h
 create mode 100644 siv.h
 create mode 100644 siv_gnutls.c
 create mode 100644 siv_nettle.c
 create mode 100644 siv_nettle_int.c
 create mode 100644 smooth.c
 create mode 100644 smooth.h
 create mode 100644 socket.c
 create mode 100644 socket.h
 create mode 100644 sources.c
 create mode 100644 sources.h
 create mode 100644 sourcestats.c
 create mode 100644 sourcestats.h
 create mode 100644 srcparams.h
 create mode 100644 stubs.c
 create mode 100644 sys.c
 create mode 100644 sys.h
 create mode 100644 sys_generic.c
 create mode 100644 sys_generic.h
 create mode 100644 sys_linux.c
 create mode 100644 sys_linux.h
 create mode 100644 sys_macosx.c
 create mode 100644 sys_macosx.h
 create mode 100644 sys_netbsd.c
 create mode 100644 sys_netbsd.h
 create mode 100644 sys_null.c
 create mode 100644 sys_null.h
 create mode 100644 sys_posix.c
 create mode 100644 sys_posix.h
 create mode 100644 sys_solaris.c
 create mode 100644 sys_solaris.h
 create mode 100644 sys_timex.c
 create mode 100644 sys_timex.h
 create mode 100644 sysincl.h
 create mode 100644 tempcomp.c
 create mode 100644 tempcomp.h
 create mode 100755 test/compilation/001-features
 create mode 100755 test/compilation/002-scanbuild
 create mode 100755 test/compilation/003-sanitizers
 create mode 100644 test/kernel/Makefile
 create mode 100644 test/kernel/adjtime.c
 create mode 100644 test/kernel/ntpadjtime.c
 create mode 100755 test/simulation/001-defaults
 create mode 100755 test/simulation/002-largenetwork
 create mode 100755 test/simulation/003-largefreqoffset
 create mode 100755 test/simulation/004-largetimeoffset
 create mode 100755 test/simulation/005-externalstep
 create mode 100755 test/simulation/006-largejitter
 create mode 100755 test/simulation/007-largewander
 create mode 100755 test/simulation/008-ntpera
 create mode 100755 test/simulation/009-sourceselection
 create mode 100755 test/simulation/010-multrecv
 create mode 100755 test/simulation/011-asymjitter
 create mode 100755 test/simulation/012-daemonts
 create mode 100755 test/simulation/013-nameserv
 create mode 100755 test/simulation/101-poll
 create mode 100755 test/simulation/102-iburst
 create mode 100755 test/simulation/103-initstepslew
 create mode 100755 test/simulation/104-driftfile
 create mode 100755 test/simulation/105-ntpauth
 create mode 100755 test/simulation/106-refclock
 create mode 100755 test/simulation/107-allowdeny
 create mode 100755 test/simulation/108-peer
 create mode 100755 test/simulation/109-makestep
 create mode 100755 test/simulation/110-chronyc
 create mode 100755 test/simulation/111-knownclient
 create mode 100755 test/simulation/112-port
 create mode 100755 test/simulation/113-leapsecond
 create mode 100755 test/simulation/114-presend
 create mode 100755 test/simulation/115-cmdmontime
 create mode 100755 test/simulation/116-minsources
 create mode 100755 test/simulation/117-fallbackdrift
 create mode 100755 test/simulation/118-maxdelay
 create mode 100755 test/simulation/119-smoothtime
 create mode 100755 test/simulation/120-selectoptions
 create mode 100755 test/simulation/121-orphan
 create mode 100755 test/simulation/122-xleave
 create mode 100755 test/simulation/123-mindelay
 create mode 100755 test/simulation/124-tai
 create mode 100755 test/simulation/125-packetloss
 create mode 100755 test/simulation/126-burst
 create mode 100755 test/simulation/127-filter
 create mode 100755 test/simulation/128-nocontrol
 create mode 100755 test/simulation/129-reload
 create mode 100755 test/simulation/130-quit
 create mode 100755 test/simulation/131-maxchange
 create mode 100755 test/simulation/132-logchange
 create mode 100755 test/simulation/133-hwtimestamp
 create mode 100755 test/simulation/134-log
 create mode 100755 test/simulation/135-ratelimit
 create mode 100755 test/simulation/136-broadcast
 create mode 100755 test/simulation/137-pool
 create mode 100755 test/simulation/138-syncloop
 create mode 100755 test/simulation/139-nts
 create mode 100755 test/simulation/140-noclientlog
 create mode 100755 test/simulation/141-copy
 create mode 100755 test/simulation/142-ptpport
 create mode 100755 test/simulation/143-manual
 create mode 100755 test/simulation/144-exp1
 create mode 100755 test/simulation/145-rtc
 create mode 100755 test/simulation/146-offline
 create mode 100755 test/simulation/147-refresh
 create mode 100755 test/simulation/148-replacement
 create mode 100755 test/simulation/201-freqaccumulation
 create mode 100755 test/simulation/202-prefer
 create mode 100644 test/simulation/README
 create mode 100755 test/simulation/run
 create mode 100644 test/simulation/test.common
 create mode 100755 test/system/001-minimal
 create mode 100755 test/system/002-extended
 create mode 100755 test/system/003-memlock
 create mode 100755 test/system/004-priority
 create mode 100755 test/system/006-privdrop
 create mode 100755 test/system/007-cmdmon
 create mode 100755 test/system/008-confload
 create mode 100755 test/system/009-binddevice
 create mode 100755 test/system/010-nts
 create mode 100755 test/system/099-scfilter
 create mode 100755 test/system/100-clockupdate
 create mode 100755 test/system/101-rtc
 create mode 100755 test/system/102-hwtimestamp
 create mode 100755 test/system/103-refclock
 create mode 100755 test/system/104-systemdirs
 create mode 100755 test/system/199-scfilter
 create mode 100755 test/system/run
 create mode 100644 test/system/test.common
 create mode 100644 test/unit/Makefile.in
 create mode 100644 test/unit/addrfilt.c
 create mode 100644 test/unit/array.c
 create mode 100644 test/unit/clientlog.c
 create mode 100644 test/unit/cmac.c
 create mode 100644 test/unit/hash.c
 create mode 100644 test/unit/hwclock.c
 create mode 100644 test/unit/keys.c
 create mode 100644 test/unit/ntp_auth.c
 create mode 100644 test/unit/ntp_core.c
 create mode 100644 test/unit/ntp_core.keys
 create mode 100644 test/unit/ntp_ext.c
 create mode 100644 test/unit/ntp_sources.c
 create mode 100644 test/unit/nts_ke.crt
 create mode 100644 test/unit/nts_ke.key
 create mode 100644 test/unit/nts_ke_client.c
 create mode 100644 test/unit/nts_ke_server.c
 create mode 100644 test/unit/nts_ke_session.c
 create mode 100644 test/unit/nts_ntp_auth.c
 create mode 100644 test/unit/nts_ntp_client.c
 create mode 100644 test/unit/nts_ntp_server.c
 create mode 100644 test/unit/quantiles.c
 create mode 100644 test/unit/regress.c
 create mode 100644 test/unit/samplefilt.c
 create mode 100644 test/unit/siv.c
 create mode 100644 test/unit/smooth.c
 create mode 100644 test/unit/sources.c
 create mode 100644 test/unit/test.c
 create mode 100644 test/unit/test.h
 create mode 100644 test/unit/util.c
 create mode 100644 util.c
 create mode 100644 util.h
 create mode 100644 version.txt

diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..d511905
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
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+  When we speak of free software, we are referring to freedom, not
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+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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+  0. This License applies to any program or other work which contains
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+You may charge a fee for the physical act of transferring a copy, and
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+Each version is given a distinguishing version number.  If the Program
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+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
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+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
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+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
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+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
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+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
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+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+		     END OF TERMS AND CONDITIONS
+
+	    How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
diff --git a/FAQ b/FAQ
new file mode 100644
index 0000000..003a2f2
--- /dev/null
+++ b/FAQ
@@ -0,0 +1,1095 @@
+Frequently Asked Questions
+
+Table of Contents
+
+  o 1. chrony compared to other programs
+      ? 1.1. How does chrony compare to ntpd?
+      ? 1.2. Should I prefer chrony over timesyncd if I do not need to run a
+        server?
+  o 2. Configuration issues
+      ? 2.1. What is the minimum recommended configuration for an NTP client?
+      ? 2.2. How do I make an NTP server?
+      ? 2.3. Should all computers on a LAN be clients of an external server?
+      ? 2.4. Must I specify servers by IP address if DNS is not available on
+        chronyd start?
+      ? 2.5. How can I make chronyd more secure?
+      ? 2.6. How can I make the system clock more secure?
+      ? 2.7. How can I improve the accuracy of the system clock with NTP
+        sources?
+      ? 2.8. Does chronyd have an ntpdate mode?
+      ? 2.9. Can chronyd be configured to control the clock like ntpd?
+      ? 2.10. Can NTP server be separated from NTP client?
+      ? 2.11. Should be a leap smear enabled on NTP server?
+      ? 2.12. How should chronyd be configured with gpsd?
+      ? 2.13. Does chrony support PTP?
+      ? 2.14. How can I avoid using wrong PHC refclock?
+      ? 2.15. Why are client log records dropped before reaching
+        clientloglimit?
+      ? 2.16. What happened to the commandkey and generatecommandkey
+        directives?
+  o 3. Computer is not synchronising
+      ? 3.1. Behind a firewall?
+      ? 3.2. Are NTP servers specified with the offline option?
+      ? 3.3. Is name resolution working correctly?
+      ? 3.4. Is chronyd allowed to step the system clock?
+      ? 3.5. Using NTS?
+      ? 3.6. Using a Windows NTP server?
+      ? 3.7. An unreachable source is selected?
+      ? 3.8. Does selected source drop new measurements?
+      ? 3.9. Using a PPS reference clock?
+  o 4. Issues with chronyc
+      ? 4.1. I keep getting the error 506 Cannot talk to daemon
+      ? 4.2. I keep getting the error 501 Not authorised
+      ? 4.3. What is the reference ID reported by the tracking command?
+      ? 4.4. Is the chronyc / chronyd protocol documented anywhere?
+  o 5. Real-time clock issues
+      ? 5.1. What is the real-time clock (RTC)?
+      ? 5.2. Does hwclock have to be disabled?
+      ? 5.3. I just keep getting the 513 RTC driver not running message
+      ? 5.4. I get Could not open /dev/rtc, Device or resource busy in my
+        syslog file
+      ? 5.5. When I start chronyd, the log says Could not enable RTC interrupt
+        : Invalid argument (or it may say disable)
+      ? 5.6. What if my computer does not have an RTC or backup battery?
+  o 6. NTP-specific issues
+      ? 6.1. Can chronyd be driven from broadcast/multicast NTP servers?
+      ? 6.2. Can chronyd transmit broadcast NTP packets?
+      ? 6.3. Can chronyd keep the system clock a fixed offset away from real
+        time?
+      ? 6.4. What happens if the network connection is dropped without using
+        chronyc's offline command first?
+      ? 6.5. Why is an offset measured between two computers synchronised to
+        each another?
+  o 7. Operation
+      ? 7.1. What clocks does chronyd use?
+  o 8. Operating systems
+      ? 8.1. Does chrony support Windows?
+      ? 8.2. Are there any plans to support Windows?
+
+1. chrony compared to other programs
+
+1.1. How does chrony compare to ntpd?
+
+chrony and ntpd are two different implementations of the Network Time Protocol
+(NTP).
+
+chrony is a newer implementation, which was designed to work well in a wider
+range of conditions. It can usually synchronise the system clock faster and
+with better time accuracy. It has many features, but it does not implement some
+of the less useful NTP modes like broadcast client or multicast server/client.
+
+If your computer is connected to the Internet only for few minutes at a time,
+the network connection is often congested, you turn your computer off or
+suspend it frequently, the clock is not very stable (e.g. there are rapid
+changes in the temperature or it is a virtual machine), or you want to use NTP
+on an isolated network with no hardware reference clocks in sight, chrony will
+probably work better for you.
+
+For a more detailed comparison of features and performance, see the comparison
+page on the chrony website.
+
+1.2. Should I prefer chrony over timesyncd if I do not need to run a server?
+
+Generally, yes.
+
+systemd-timesyncd is a very simple NTP client included in the systemd suite. It
+lacks almost all features of chrony and other advanced client implementations
+listed on the comparison page. One of its main limitations is that it cannot
+poll multiple servers at the same time and detect servers having incorrect time
+(falsetickers in the NTP terminology). It should be used only with trusted
+reliable servers, ideally in local network.
+
+Using timesyncd with pool.ntp.org is problematic. The pool is very robust as a
+whole, but the individual servers run by volunteers cannot be relied on.
+Occasionally, servers drift away or make a step to distant past or future due
+to misconfiguration, problematic implementation, and other bugs (e.g. in
+firmware of a GPS receiver). The pool monitoring system detects such servers
+and quickly removes them from the pool DNS, but clients like timesyncd cannot
+recover from that. They follow the server as long as it claims to be
+synchronised. They need to be restarted in order to get a new address from the
+pool DNS.
+
+Note that the complexity of NTP and clock synchronisation is on the client
+side. The amount of code in chrony specific to NTP server is very small and it
+is disabled by default. If it was removed, it would not significantly reduce
+the amount of memory or storage needed.
+
+2. Configuration issues
+
+2.1. What is the minimum recommended configuration for an NTP client?
+
+First, the client needs to know which NTP servers it should ask for the current
+time. They are specified by the server or pool directive. The pool directive is
+used with names that resolve to multiple addresses of different servers. For
+reliable operation, the client should have at least three servers.
+
+The iburst option enables a burst of requests to speed up the initial
+synchronisation.
+
+To stabilise the initial synchronisation on the next start, the estimated drift
+of the system clock is saved to a file specified by the driftfile directive.
+
+If the system clock can be far from the true time after boot for any reason,
+chronyd should be allowed to correct it quickly by stepping instead of slewing,
+which would take a very long time. The makestep directive does that.
+
+In order to keep the real-time clock (RTC) close to the true time, so the
+system time is reasonably close to the true time when it is initialised on the
+next boot from the RTC, the rtcsync directive enables a mode in which the
+system time is periodically copied to the RTC. It is supported on Linux and
+macOS.
+
+If you wanted to use public NTP servers from the pool.ntp.org project, the
+minimal chrony.conf file could be:
+
+pool pool.ntp.org iburst
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+
+2.2. How do I make an NTP server?
+
+By default, chronyd does not operate as an NTP server. You need to add an allow
+directive to the chrony.conf file in order for chronyd to open the server NTP
+port and respond to client requests.
+
+allow 192.168.1.0/24
+
+An allow directive with no specified subnet allows access from all IPv4 and
+IPv6 addresses.
+
+2.3. Should all computers on a LAN be clients of an external server?
+
+It depends on the requirements. Usually, the best configuration is to make one
+computer the server, with the others as clients of it. Add a local directive to
+the server's chrony.conf file. This configuration will be better because
+
+  o the load on the external connection is less
+
+  o the load on the external NTP server(s) is less
+
+  o if your external connection goes down, the computers on the LAN will
+    maintain a common time with each other.
+
+2.4. Must I specify servers by IP address if DNS is not available on chronyd
+start?
+
+No, chronyd will keep trying to resolve the names specified by the server,
+pool, and peer directives in an increasing interval until it succeeds. The
+online command can be issued from chronyc to force chronyd to try to resolve
+the names immediately.
+
+2.5. How can I make chronyd more secure?
+
+If you do not need to use chronyc, or you want to run chronyc only under the
+root or chrony user (which can access chronyd through a Unix domain socket),
+you can disable the IPv4 and IPv6 command sockets (by default listening on
+localhost) by adding cmdport 0 to the configuration file.
+
+You can specify an unprivileged user with the -u option, or the user directive
+in the chrony.conf file, to which chronyd will switch after start in order to
+drop root privileges. The configure script has a --with-user option, which sets
+the default user. On Linux, chronyd needs to be compiled with support for the
+libcap library. On other systems, chronyd forks into two processes. The child
+process retains root privileges, but can only perform a very limited range of
+privileged system calls on behalf of the parent.
+
+Also, if chronyd is compiled with support for the Linux secure computing
+(seccomp) facility, you can enable a system call filter with the -F option. It
+will significantly reduce the kernel attack surface and possibly prevent kernel
+exploits from the chronyd process if it is compromised. It is recommended to
+enable the filter only when it is known to work on the version of the system
+where chrony is installed as the filter needs to allow also system calls made
+from libraries that chronyd is using (e.g. libc) and different versions or
+implementations of the libraries might make different system calls. If the
+filter is missing some system call, chronyd could be killed even in normal
+operation.
+
+2.6. How can I make the system clock more secure?
+
+An NTP client synchronising the system clock to an NTP server is susceptible to
+various attacks, which can break applications and network protocols relying on
+accuracy of the clock (e.g. DNSSEC, Kerberos, TLS, WireGuard).
+
+Generally, a man-in-the-middle (MITM) attacker between the client and server
+can
+
+  o make fake responses, or modify real responses from the server, to create an
+    arbitrarily large time and frequency offset, make the server appear more
+    accurate, insert a leap second, etc.
+
+  o delay the requests and/or responses to create a limited time offset and
+    temporarily also a limited frequency offset
+
+  o drop the requests or responses to prevent updates of the clock with new
+    measurements
+
+  o redirect the requests to a different server
+
+The attacks can be combined for a greater effect. The attacker can delay
+packets to create a significant frequency offset first and then drop all
+subsequent packets to let the clock quickly drift away from the true time. The
+attacker might also be able to control the server's clock.
+
+Some attacks cannot be prevented. Monitoring is needed for detection, e.g. the
+reachability register in the sources report shows missing packets. The extent
+to which the attacker can control the client's clock depends on its
+configuration.
+
+Enable authentication to prevent chronyd from accepting modified, fake, or
+redirected packets. It can be enabled with a symmetric key specified by the key
+option, or Network Time Security (NTS) by the nts option (supported since
+chrony version 4.0). The server needs to support the selected authentication
+mechanism. Symmetric keys have to be configured on both client and server, and
+each client must have its own key (one per server).
+
+The maximum offset that the attacker can insert in an NTP measurement by
+delaying packets can be limited by the maxdelay option. The default value is 3
+seconds. The measured delay is reported as the peer delay in the ntpdata report
+and measurements log. Set the maxdelay option to a value larger than the
+maximum value that is normally observed. Note that the delay can increase
+significantly even when not under an attack, e.g. when the network is congested
+or the routing has changed.
+
+The maximum accepted change in time offset between clock updates can be limited
+by the maxchange directive. Larger changes in the offset will be ignored or
+cause chronyd to exit. Note that the attacker can get around this limit by
+splitting the offset into multiple smaller offsets and/or creating a large
+frequency offset. When this directive is used, chronyd will have to be
+restarted after a successful attack. It will not be able to recover on its own.
+It must not be restarted automatically (e.g. by the service manager).
+
+The impact of a large accepted time offset can be reduced by disabling clock
+steps, i.e. by not using the makestep and initstepslew directives. The offset
+will be slowly corrected by speeding up or slowing down the clock at a rate
+which can be limited by the maxslewrate directive. Disabling clock steps
+completely is practical only if the clock cannot gain a larger error on its
+own, e.g. when the computer is shut down or suspended, and the maxslewrate
+limit is large enough to correct an expected error in an acceptable time. The
+rtcfile directive with the -s option can be used to compensate for the RTC
+drift.
+
+A more practical approach is to enable makestep for a limited number of clock
+updates (the 2nd argument of the directive) and limit the offset change in all
+updates by the maxchange directive. The attacker will be able to make only a
+limited step and only if the attack starts in a short window after booting the
+computer, or when chronyd is restarted without the -R option.
+
+The frequency offset can be limited by the maxdrift directive. The measured
+frequency offset is reported in the drift file, tracking report, and tracking
+log. Set maxdrift to a value larger than the maximum absolute value that is
+normally observed. Note that the frequency of the clock can change due to aging
+of the crystal, differences in calibration of the clock source between reboots,
+migrated virtual machine, etc. A typical computer clock has a drift smaller
+than 100 parts per million (ppm), but much larger drifts are possible (e.g. in
+some virtual machines).
+
+Use only trusted servers, which you expect to be well configured and managed,
+using authentication for their own servers, etc. Use multiple servers, ideally
+in different locations. The attacker will have to deal with a majority of the
+servers in order to pass the source selection and update the clock with a large
+offset. Use the minsources directive to increase the required number of
+selectable sources to make the selection more robust.
+
+Do not specify servers as peers. The symmetric mode is less secure than the
+client/server mode. If not authenticated, it is vulnerable to off-path
+denial-of-service attacks, and even when it is authenticated, it is still
+susceptible to replay attacks.
+
+Mixing of authenticated and unauthenticated servers should generally be
+avoided. If mixing is necessary (e.g. for a more accurate and stable
+synchronisation to a closer server which does not support authentication), the
+authenticated servers should be configured as trusted and required to not allow
+the unauthenticated servers to override the authenticated servers in the source
+selection. Since chrony version 4.0, the selection options are enabled in such
+a case automatically. This behaviour can be disabled or modified by the
+authselectmode directive.
+
+An example of a client configuration limiting the impact of the attacks could
+be
+
+server foo.example.net iburst nts maxdelay 0.1
+server bar.example.net iburst nts maxdelay 0.2
+server baz.example.net iburst nts maxdelay 0.05
+server qux.example.net iburst nts maxdelay 0.1
+server quux.example.net iburst nts maxdelay 0.1
+minsources 3
+maxchange 100 0 0
+makestep 0.001 1
+maxdrift 100
+maxslewrate 100
+driftfile /var/lib/chrony/drift
+ntsdumpdir /var/lib/chrony
+rtcsync
+
+2.7. How can I improve the accuracy of the system clock with NTP sources?
+
+Select NTP servers that are well synchronised, stable and close to your
+network. It is better to use more than one server. Three or four is usually
+recommended as the minimum, so chronyd can detect servers that serve false time
+and combine measurements from multiple sources.
+
+If you have a network card with hardware timestamping supported on Linux, it
+can be enabled by the hwtimestamp directive. It should make local receive and
+transmit timestamps of NTP packets much more stable and accurate.
+
+The server directive has some useful options: minpoll, maxpoll, polltarget,
+maxdelay, maxdelayratio, maxdelaydevratio, xleave, filter.
+
+The first three options set the minimum and maximum allowed polling interval,
+and how should be the actual interval adjusted in the specified range. Their
+default values are 6 (64 seconds) for minpoll, 10 (1024 seconds) for maxpoll
+and 8 (samples) for polltarget. The default values should be used for general
+servers on the Internet. With your own NTP servers, or if you have permission
+to poll some servers more frequently, setting these options for shorter polling
+intervals might significantly improve the accuracy of the system clock.
+
+The optimal polling interval depends mainly on two factors, stability of the
+network latency and stability of the system clock (which mainly depends on the
+temperature sensitivity of the crystal oscillator and the maximum rate of the
+temperature change).
+
+Generally, if the sourcestats command usually reports a small number of samples
+retained for a source (e.g. fewer than 16), a shorter polling interval should
+be considered. If the number of samples is usually at the maximum of 64, a
+longer polling interval might work better.
+
+An example of the directive for an NTP server on the Internet that you are
+allowed to poll frequently could be
+
+server foo.example.net minpoll 4 maxpoll 6 polltarget 16
+
+An example using shorter polling intervals with a server located in the same
+LAN could be
+
+server ntp.local minpoll 2 maxpoll 4 polltarget 30
+
+The maxdelay options are useful to ignore measurements with an unusually large
+delay (e.g. due to congestion in the network) and improve the stability of the
+synchronisation. The maxdelaydevratio option could be added to the example with
+local NTP server
+
+server ntp.local minpoll 2 maxpoll 4 polltarget 30 maxdelaydevratio 2
+
+If your server supports the interleaved mode (e.g. it is running chronyd), the
+xleave option should be added to the server directive to enable the server to
+provide the client with more accurate transmit timestamps (kernel or preferably
+hardware). For example:
+
+server ntp.local minpoll 2 maxpoll 4 xleave
+
+When combined with local hardware timestamping, good network switches, and even
+shorter polling intervals, a sub-microsecond accuracy and stability of a few
+tens of nanoseconds might be possible. For example:
+
+server ntp.local minpoll 0 maxpoll 0 xleave
+hwtimestamp eth0
+
+For best stability, the CPU should be running at a constant frequency (i.e.
+disabled power saving and performance boosting). Energy-Efficient Ethernet
+(EEE) should be disabled in the network. The switches should be configured to
+prioritize NTP packets, especially if the network is expected to be heavily
+loaded. The dscp directive can be used to set the Differentiated Services Code
+Point in transmitted NTP packets if needed.
+
+If it is acceptable for NTP clients in the network to send requests at a high
+rate, a sub-second polling interval can be specified. A median filter can be
+enabled in order to update the clock at a reduced rate with more stable
+measurements. For example:
+
+server ntp.local minpoll -6 maxpoll -6 filter 15 xleave
+hwtimestamp eth0 minpoll -6
+
+Since chrony version 4.3, the minimum minpoll is -7 and a filter using a
+long-term estimate of a delay quantile can be enabled by the maxdelayquant
+option to replace the default maxdelaydevratio filter, which is sensitive to
+outliers corrupting the minimum delay. For example:
+
+server ntp.local minpoll -7 maxpoll -7 filter 31 maxdelayquant 0.3 xleave
+
+As an experimental feature added in version 4.2, chronyd supports an NTPv4
+extension field containing an additional timestamp to enable frequency transfer
+and significantly improve stability of synchronisation. It can be enabled by
+the extfield F323 option. For example:
+
+server ntp.local minpoll 0 maxpoll 0 xleave extfield F323
+
+2.8. Does chronyd have an ntpdate mode?
+
+Yes. With the -q option chronyd will set the system clock once and exit. With
+the -Q option it will print the measured offset without setting the clock. If
+you do not want to use a configuration file, NTP servers can be specified on
+the command line. For example:
+
+# chronyd -q 'pool pool.ntp.org iburst'
+
+The command above would normally take about 5 seconds if the servers were well
+synchronised and responding to all requests. If not synchronised or responding,
+it would take about 10 seconds for chronyd to give up and exit with a non-zero
+status. A faster configuration is possible. A single server can be used instead
+of four servers, the number of measurements can be reduced with the maxsamples
+option to one (supported since chrony version 4.0), and a timeout can be
+specified with the -t option. The following command would take only up to about
+one second.
+
+# chronyd -q -t 1 'server pool.ntp.org iburst maxsamples 1'
+
+It is not recommended to run chronyd with the -q option periodically (e.g. from
+a cron job) as a replacement for the daemon mode, because it performs
+significantly worse (e.g. the clock is stepped and its frequency is not
+corrected). If you must run it this way and you are using a public NTP server,
+make sure chronyd does not always start around the first second of a minute,
+e.g. by adding a random sleep before the chronyd command. Public servers
+typically receive large bursts of requests around the first second as there is
+a large number of NTP clients started from cron with no delay.
+
+2.9. Can chronyd be configured to control the clock like ntpd?
+
+It is not possible to perfectly emulate ntpd, but there are some options that
+can configure chronyd to behave more like ntpd if there is a reason to prefer
+that.
+
+In the following example the minsamples directive slows down the response to
+changes in the frequency and offset of the clock. The maxslewrate and
+corrtimeratio directives reduce the maximum frequency error due to an offset
+correction and the maxdrift directive reduces the maximum assumed frequency
+error of the clock. The makestep directive enables a step threshold and the
+maxchange directive enables a panic threshold. The maxclockerror directive
+increases the minimum dispersion rate.
+
+minsamples 32
+maxslewrate 500
+corrtimeratio 100
+maxdrift 500
+makestep 0.128 -1
+maxchange 1000 1 1
+maxclockerror 15
+
+Note that increasing minsamples might cause the offsets in the tracking and
+sourcestats reports/logs to be significantly smaller than the actual offsets
+and be unsuitable for monitoring.
+
+2.10. Can NTP server be separated from NTP client?
+
+Yes, it is possible to run multiple instances of chronyd on a computer at the
+same time. One can operate primarily as an NTP client to synchronise the system
+clock and another as a server for other computers. If they use the same
+filesystem, they need to be configured with different pidfiles, Unix domain
+command sockets, and any other file or directory specified in the configuration
+file. If they run in the same network namespace, they need to use different NTP
+and command ports, or bind the ports to different addresses or interfaces.
+
+The server instance should be started with the -x option to prevent it from
+adjusting the system clock and interfering with the client instance. It can be
+configured as a client to synchronise its NTP clock to other servers, or the
+client instance running on the same computer. In the latter case, the copy
+option (added in chrony version 4.1) can be used to assume the reference ID and
+stratum of the client instance, which enables detection of synchronisation
+loops with its own clients.
+
+On Linux, starting with chrony version 4.0, it is possible to run multiple
+server instances sharing a port to better utilise multiple cores of the CPU.
+Note that for rate limiting and client/server interleaved mode to work well it
+is necessary that all packets received from the same address are handled by the
+same server instance.
+
+An example configuration of the client instance could be
+
+pool pool.ntp.org iburst
+allow 127.0.0.1
+port 11123
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+
+and configuration of the first server instance could be
+
+server 127.0.0.1 port 11123 minpoll 0 maxpoll 0 copy
+allow
+cmdport 11323
+bindcmdaddress /var/run/chrony/chronyd-server1.sock
+pidfile /var/run/chronyd-server1.pid
+driftfile /var/lib/chrony/drift-server1
+
+2.11. Should be a leap smear enabled on NTP server?
+
+With the smoothtime and leapsecmode directives it is possible to enable a
+server leap smear in order to hide leap seconds from clients and force them to
+follow a slow server's adjustment instead.
+
+This feature should be used only in local networks and only when necessary,
+e.g. when the clients cannot be configured to handle the leap seconds as
+needed, or their number is so large that configuring them all would be
+impractical. The clients should use only one leap-smearing server, or multiple
+identically configured leap-smearing servers. Note that some clients can get
+leap seconds from other sources (e.g. with the leapsectz directive in chrony)
+and they will not work correctly with a leap smearing server.
+
+2.12. How should chronyd be configured with gpsd?
+
+A GPS or other GNSS receiver can be used as a reference clock with gpsd. It can
+work as one or two separate time sources for each connected receiver. The first
+time source is based on timestamping of messages sent by the receiver.
+Typically, it is accurate to milliseconds. The other source is much more
+accurate. It is timestamping a pulse-per-second (PPS) signal, usually connected
+to a serial port (e.g. DCD pin) or GPIO pin.
+
+If the PPS signal is connected to the serial port which is receiving messages
+from the GPS/GNSS receiver, gpsd should detect and use it automatically. If it
+is connected to a GPIO pin, or another serial port, the PPS device needs to be
+specified on the command line as an additional data source. On Linux, the
+ldattach utility can be used to create a PPS device for a serial device.
+
+The PPS-based time source provided by gpsd is available as a SHM 1 refclock, or
+other odd number if gpsd is configured with multiple receivers, and also as
+SOCK /var/run/chrony.DEV.sock where DEV is the name of the serial device (e.g.
+ttyS0).
+
+The message-based time source is available as a SHM 0 refclock (or other even
+number) and since gpsd version 3.25 also as SOCK /var/run/chrony.clk.DEV.sock
+where DEV is the name of the serial device.
+
+The SOCK refclocks should be preferred over SHM for better security (the shared
+memory segment needs to be created by chronyd or gpsd with an expected owner
+and permissions before an untrusted application or user has a chance to create
+its own in order to feed chronyd with false measurements). gpsd needs to be
+started after chronyd in order to connect to the socket.
+
+With chronyd and gpsd both supporting PPS, there are two different recommended
+configurations:
+
+# First option
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS
+
+# Second option
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.1 refid NMEA noselect
+
+They both have some advantages:
+
+  o SOCK can be more accurate than PPS if gpsd corrects for the sawtooth error
+    provided by the receiver in serial data
+
+  o PPS can be used with higher PPS rates (specified by the rate option), but
+    it requires a second refclock or another time source to pair pulses with
+    seconds, and the SOCK offset needs to be specified correctly to compensate
+    for the message delay, while gpsd can apply HW-specific information
+
+If the PPS signal is not available, or cannot be used for some reason, the only
+option is the message-based timing
+
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.1 refid GPS
+
+or the SHM equivalent if using gpsd version before 3.25
+
+refclock SHM 0 offset 0.5 delay 0.1 refid GPS
+
+2.13. Does chrony support PTP?
+
+No, the Precision Time Protocol (PTP) is not supported as a protocol for
+synchronisation of clocks and there are no plans to support it. It is a complex
+protocol, which shares some issues with the NTP broadcast mode. One of the main
+differences between NTP and PTP is that PTP was designed to be easily supported
+in hardware (e.g. network switches and routers) in order to make more stable
+and accurate measurements. PTP relies on the hardware support. NTP does not
+rely on any support in the hardware, but if it had the same support as PTP, it
+could perform equally well.
+
+On Linux, chrony supports hardware clocks that some NICs have for PTP. They are
+called PTP hardware clocks (PHC). They can be used as reference clocks
+(specified by the refclock directive) and for hardware timestamping of NTP
+packets (enabled by the hwtimestamp directive) if the NIC can timestamp other
+packets than PTP, which is usually the case at least for transmitted packets.
+The ethtool -T command can be used to verify the timestamping support.
+
+As an experimental feature added in version 4.2, chrony can use PTP as a
+transport for NTP messages (NTP over PTP) to enable hardware timestamping on
+hardware which can timestamp PTP packets only. It can be enabled by the ptpport
+directive.
+
+2.14. How can I avoid using wrong PHC refclock?
+
+If your system has multiple PHC devices, normally named by udev as /dev/ptp0, /
+dev/ptp1, and so on, their order can change randomly across reboots depending
+on the order of initialisation of their drivers. If a PHC refclock is specified
+by this name, chronyd could be using a wrong refclock after reboot. To prevent
+that, you can configure udev to create a stable symlink for chronyd with a rule
+like this (e.g. written to /etc/udev/rules.d/80-phc.rules):
+
+KERNEL=="ptp[0-9]*", DEVPATH=="/devices/pci0000:00/0000:00:01.2/0000:02:00.0/ptp/*", SYMLINK+="ptp-i350-1"
+
+You can get the full DEVPATH of an existing PHC device with the udevadm info
+command. You will need to execute the udevadm trigger command, or reboot the
+system, for these changes to take effect.
+
+2.15. Why are client log records dropped before reaching clientloglimit?
+
+The number of dropped client log records reported by the serverstats command
+can be increasing before the number of clients reported by the clients command
+reaches the maximum value corresponding to the memory limit set by the
+clientloglimit directive.
+
+This is due to the design of the data structure keeping the client records. It
+is a hash table which can store only up to 16 colliding addresses per slot. If
+a slot has more collisions and the table already has the maximum size, the
+oldest record will be dropped and replaced by the new client.
+
+Note that the size of the table is always a power of two and it can only grow.
+The limit set by the clientloglimit directive takes into account that two
+copies of the table exist when it is being resized. This means the actual
+memory usage reported by top and other utilities can be significantly smaller
+than the limit even when the maximum number of records is used.
+
+The absolute maximum number of client records kept at the same time is
+16777216.
+
+2.16. What happened to the commandkey and generatecommandkey directives?
+
+They were removed in version 2.2. Authentication is no longer supported in the
+command protocol. Commands that required authentication are now allowed only
+through a Unix domain socket, which is accessible only by the root and chrony
+users. If you need to configure chronyd remotely or locally without the root
+password, please consider using ssh and/or sudo to run chronyc under the root
+or chrony user on the host where chronyd is running.
+
+3. Computer is not synchronising
+
+This is the most common problem. There are a number of reasons, see the
+following questions.
+
+3.1. Behind a firewall?
+
+Check the Reach value printed by the chronyc's sources command. If it is zero,
+it means chronyd did not get any valid responses from the NTP server you are
+trying to use. If there is a firewall between you and the server, the requests
+sent to the UDP port 123 of the server or responses sent back from the port
+might be blocked. Try using a tool like wireshark or tcpdump to see if you are
+getting any responses from the server.
+
+When chronyd is receiving responses from the servers, the output of the sources
+command issued few minutes after chronyd start might look like this:
+
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+^* foo.example.net               2   6   377    34   +484us[ -157us] +/-   30ms
+^- bar.example.net               2   6   377    34    +33ms[  +32ms] +/-   47ms
+^+ baz.example.net               3   6   377    35  -1397us[-2033us] +/-   60ms
+
+3.2. Are NTP servers specified with the offline option?
+
+Check that the chronyc's online and offline commands are used appropriately
+(e.g. in the system networking scripts). The activity command prints the number
+of sources that are currently online and offline. For example:
+
+200 OK
+3 sources online
+0 sources offline
+0 sources doing burst (return to online)
+0 sources doing burst (return to offline)
+0 sources with unknown address
+
+3.3. Is name resolution working correctly?
+
+NTP servers specified by their hostname (instead of an IP address) have to have
+their names resolved before chronyd can send any requests to them. If the
+activity command prints a non-zero number of sources with unknown address,
+there is an issue with the resolution. Typically, a DNS server is specified in
+/etc/resolv.conf. Make sure it is working correctly.
+
+Since chrony version 4.0, you can run chronyc -N sources -a command to print
+all sources, even those that do not have a known address yet, with their names
+as they were specified in the configuration. This can be useful to verify that
+the names specified in the configuration are used as expected.
+
+3.4. Is chronyd allowed to step the system clock?
+
+By default, chronyd adjusts the clock gradually by slowing it down or speeding
+it up. If the clock is too far from the true time, it will take a long time to
+correct the error. The System time value printed by the chronyc's tracking
+command is the remaining correction that needs to be applied to the system
+clock.
+
+The makestep directive can be used to allow chronyd to step the clock. For
+example, if chrony.conf had
+
+makestep 1 3
+
+the clock would be stepped in the first three updates if its offset was larger
+than one second. Normally, it is recommended to allow the step only in the
+first few updates, but in some cases (e.g. a computer without an RTC or virtual
+machine which can be suspended and resumed with an incorrect time) it might be
+necessary to allow the step on any clock update. The example above would change
+to
+
+makestep 1 -1
+
+3.5. Using NTS?
+
+The Network Time Security (NTS) mechanism uses Transport Layer Security (TLS)
+to establish the keys needed for authentication of NTP packets.
+
+Run the authdata command to check whether the key establishment was successful:
+
+# chronyc -N authdata
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256  33m    0    0    8  100
+bar.example.net              NTS     1   15  256  33m    0    0    8  100
+baz.example.net              NTS     1   15  256  33m    0    0    8  100
+
+The KeyID, Type, and KLen columns should have non-zero values. If they are
+zero, check the system log for error messages from chronyd. One possible cause
+of failure is a firewall blocking the client's connection to the server's TCP
+port 4460.
+
+Another possible cause of failure is a certificate that is failing to verify
+because the client's clock is wrong. This is a chicken-and-egg problem with
+NTS. You might need to manually correct the date, or temporarily disable NTS,
+in order to get NTS working. If your computer has an RTC and it is backed up by
+a good battery, this operation should be needed only once, assuming the RTC
+will be set periodically with the rtcsync directive, or compensated with the
+rtcfile directive and the -s option.
+
+If the computer does not have an RTC or battery, you can use the -s option
+without rtcfile directive to restore time of the last shutdown or reboot from
+the drift file. The clock will start behind the true time, but if the computer
+was not shut down for too long and the server's certificate was not renewed too
+close to its expiration, it should be sufficient for the time checks to
+succeed.
+
+If you run your own server, you can use a self-signed certificate covering all
+dates where the client can start (e.g. years 1970-2100). The certificate needs
+to be installed on the client and specified with the ntstrustedcerts directive.
+The server can have multiple names and certificates. To avoid trusting a
+certificate for too long, a new certificate can be added to the server
+periodically (e.g. once per year) and the client can have the server name and
+trusted certificate updated automatically (e.g. using a package repository, or
+a cron script downloading the files directly from the server over HTTPS). A
+client that was shut down for years will still be able to synchronise its clock
+and perform the update as long as the server keeps the old certificate.
+
+As a last resort, you can disable the time checks by the nocerttimecheck
+directive. This has some important security implications. To reduce the
+security risk, you can use the nosystemcert and ntstrustedcerts directives to
+disable the system's default trusted certificate authorities and trust only a
+minimal set of selected authorities needed to validate the certificates of used
+NTP servers.
+
+3.6. Using a Windows NTP server?
+
+A common issue with Windows NTP servers is that they report a very large root
+dispersion (e.g. three seconds or more), which causes chronyd to ignore the
+server for being too inaccurate. The sources command might show a valid
+measurement, but the server is not selected for synchronisation. You can check
+the root dispersion of the server with the chronyc's ntpdata command.
+
+The maxdistance value needs to be increased in chrony.conf to enable
+synchronisation to such a server. For example:
+
+maxdistance 16.0
+
+3.7. An unreachable source is selected?
+
+When chronyd is configured with multiple time sources, it tries to select the
+most accurate and stable sources for synchronisation of the system clock. They
+are marked with the * or + symbol in the report printed by the sources command.
+
+When the best source (marked with the * symbol) becomes unreachable (e.g. NTP
+server stops responding), chronyd will not immediately switch to the second
+best source in an attempt to minimise the error of the clock. It will let the
+clock run free for as long as its estimated error (in terms of root distance)
+based on previous measurements is smaller than the estimated error of the
+second source, and there is still an interval which contains some measurements
+from both sources.
+
+If the first source was significantly better than the second source, it can
+take many hours before the second source is selected, depending on its polling
+interval. You can force a faster reselection by increasing the clock error rate
+(maxclockerror directive), shortening the polling interval (maxpoll option), or
+reducing the number of samples (maxsamples option).
+
+3.8. Does selected source drop new measurements?
+
+chronyd can drop a large number of successive NTP measurements if they are not
+passing some of the NTP tests. The sources command can report for a selected
+source the fully-reachable value of 377 in the Reach column and at the same
+time a LastRx value that is much larger than the current polling interval. If
+the source is online, this indicates that a number of measurements was dropped.
+You can use the ntpdata command to check the NTP tests for the last
+measurement. Usually, it is the test C which fails.
+
+This can be an issue when there is a long-lasting increase in the measured
+delay, e.g. due to a routing change in the network. Unfortunately, chronyd does
+not know for how long it should wait for the delay to come back to the original
+values, or whether it is a permanent increase and it should start from scratch.
+
+The test C is an adaptive filter. It can take many hours before it accepts a
+measurement with the larger delay, and even much longer before it drops all
+measurements with smaller delay, which determine an expected delay used by the
+test. You can use the reset sources command to drop all measurements
+immediately (available in chrony 4.0 and later). If this issue happens
+frequently, you can effectively disable the test by setting the
+maxdelaydevratio option to a very large value (e.g. 1000000), or speed up the
+recovery by increasing the clock error rate with the maxclockerror directive.
+
+3.9. Using a PPS reference clock?
+
+A pulse-per-second (PPS) reference clock requires a non-PPS time source to
+determine which second of UTC corresponds to each pulse. If it is another
+reference clock specified with the lock option in the refclock directive, the
+offset between the two reference clocks must be smaller than 0.4 seconds (0.2
+seconds with chrony versions before 4.1) in order for the PPS reference clock
+to work. With NMEA reference clocks it is common to have a larger offset. It
+needs to be corrected with the offset option.
+
+One approach to find out a good value of the offset option is to configure the
+reference clocks with the noselect option and compare them to an NTP server.
+For example, if the sourcestats command showed
+
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+PPS0                        0   0     0     +0.000   2000.000     +0ns  4000ms
+NMEA                       58  30   231    -96.494     38.406   +504ms  6080us
+foo.example.net             7   3   200     -2.991     16.141   -107us   492us
+
+the offset of the NMEA source would need to be increased by about 0.504
+seconds. It does not have to be very accurate. As long as the offset of the
+NMEA reference clock stays below the limit, the PPS reference clock should be
+able to determine the seconds corresponding to the pulses and allow the samples
+to be used for synchronisation.
+
+4. Issues with chronyc
+
+4.1. I keep getting the error 506 Cannot talk to daemon
+
+When accessing chronyd remotely, make sure that the chrony.conf file (on the
+computer where chronyd is running) has a cmdallow entry for the computer you
+are running chronyc on and an appropriate bindcmdaddress directive. This is not
+necessary for localhost.
+
+Perhaps chronyd is not running. Try using the ps command (e.g. on Linux, ps
+-auxw) to see if it is running. Or try netstat -a and see if the UDP port 323
+is listening. If chronyd is not running, you might have a problem with the way
+you are trying to start it (e.g. at boot time).
+
+Perhaps you have a firewall set up in a way that blocks packets on the UDP port
+323. You need to amend the firewall configuration in this case.
+
+4.2. I keep getting the error 501 Not authorised
+
+This error indicates that chronyc sent the command to chronyd using a UDP
+socket instead of the Unix domain socket (e.g. /var/run/chrony/chronyd.sock),
+which is required for some commands. For security reasons, only the root and
+chrony users are allowed to access the socket.
+
+It is also possible that the socket does not exist. chronyd will not create the
+socket if the directory has a wrong owner or permissions. In this case there
+should be an error message from chronyd in the system log.
+
+4.3. What is the reference ID reported by the tracking command?
+
+The reference ID is a 32-bit value used in NTP to prevent synchronisation
+loops.
+
+In chrony versions before 3.0 it was printed in the quad-dotted notation, even
+if the reference source did not actually have an IPv4 address. For IPv4
+addresses, the reference ID is equal to the address, but for IPv6 addresses it
+is the first 32 bits of the MD5 sum of the address. For reference clocks, the
+reference ID is the value specified with the refid option in the refclock
+directive.
+
+Since version 3.0, the reference ID is printed as a hexadecimal number to avoid
+confusion with IPv4 addresses.
+
+If you need to get the IP address of the current reference source, use the -n
+option to disable resolving of IP addresses and read the second field (printed
+in parentheses) on the Reference ID line.
+
+4.4. Is the chronyc / chronyd protocol documented anywhere?
+
+Only by the source code. See cmdmon.c (chronyd side) and client.c (chronyc
+side).
+
+Note that this protocol is not compatible with the mode 6 or mode 7 protocol
+supported by ntpd, i.e. the ntpq or ntpdc utility cannot be used to monitor
+chronyd, and chronyc cannot be used to monitor ntpd.
+
+5. Real-time clock issues
+
+5.1. What is the real-time clock (RTC)?
+
+This is the clock which keeps the time even when your computer is turned off.
+It is used to initialise the system clock on boot. It normally does not drift
+more than few seconds per day.
+
+There are two approaches how chronyd can work with it. One is to use the
+rtcsync directive, which tells chronyd to enable a kernel mode which sets the
+RTC from the system clock every 11 minutes. chronyd itself will not touch the
+RTC. If the computer is not turned off for a long time, the RTC should still be
+close to the true time when the system clock will be initialised from it on the
+next boot.
+
+The other option is to use the rtcfile directive, which tells chronyd to
+monitor the rate at which the RTC gains or loses time. When chronyd is started
+with the -s option on the next boot, it will set the system time from the RTC
+and also compensate for the drift it has measured previously. The rtcautotrim
+directive can be used to keep the RTC close to the true time, but it is not
+strictly necessary if its only purpose is to set the system clock when chronyd
+is started on boot. See the documentation for details.
+
+5.2. Does hwclock have to be disabled?
+
+The hwclock program is run by default in the boot and/or shutdown scripts in
+some Linux installations. With the kernel RTC synchronisation (rtcsync
+directive), the RTC will be set also every 11 minutes as long as the system
+clock is synchronised. If you want to use chronyd's RTC monitoring (rtcfile
+directive), it is important to disable hwclock in the shutdown procedure. If
+you do not do that, it will overwrite the RTC with a new value, unknown to
+chronyd. At the next reboot, chronyd started with the -s option will compensate
+this (wrong) time with its estimate of how far the RTC has drifted whilst the
+power was off, giving a meaningless initial system time.
+
+There is no need to remove hwclock from the boot process, as long as chronyd is
+started after it has run.
+
+5.3. I just keep getting the 513 RTC driver not running message
+
+For the real-time clock support to work, you need the following three things
+
+  o an RTC in your computer
+
+  o a Linux kernel with enabled RTC support
+
+  o an rtcfile directive in your chrony.conf file
+
+5.4. I get Could not open /dev/rtc, Device or resource busy in my syslog file
+
+Some other program running on the system might be using the device.
+
+5.5. When I start chronyd, the log says Could not enable RTC interrupt :
+Invalid argument (or it may say disable)
+
+Your real-time clock hardware might not support the required ioctl requests:
+
+  o RTC_UIE_ON
+
+  o RTC_UIE_OFF
+
+A possible solution could be to build the Linux kernel with support for
+software emulation instead; try enabling the following configuration option
+when building the Linux kernel:
+
+  o CONFIG_RTC_INTF_DEV_UIE_EMUL
+
+5.6. What if my computer does not have an RTC or backup battery?
+
+In this case you can still use the -s option to set the system clock to the
+last modification time of the drift file, which should correspond to the system
+time when chronyd was previously stopped. The initial system time will be
+increasing across reboots and applications started after chronyd will not
+observe backward steps.
+
+6. NTP-specific issues
+
+6.1. Can chronyd be driven from broadcast/multicast NTP servers?
+
+No, the broadcast/multicast client mode is not supported and there is currently
+no plan to implement it. While this mode can simplify configuration of clients
+in large networks, it is inherently less accurate and less secure (even with
+authentication) than the ordinary client/server mode.
+
+When configuring a large number of clients in a network, it is recommended to
+use the pool directive with a DNS name which resolves to addresses of multiple
+NTP servers. The clients will automatically replace the servers when they
+become unreachable, or otherwise unsuitable for synchronisation, with new
+servers from the pool.
+
+Even with very modest hardware, an NTP server can serve time to hundreds of
+thousands of clients using the ordinary client/server mode.
+
+6.2. Can chronyd transmit broadcast NTP packets?
+
+Yes, the broadcast directive can be used to enable the broadcast server mode to
+serve time to clients in the network which support the broadcast client mode
+(it is not supported in chronyd). Note that this mode should generally be
+avoided. See the previous question.
+
+6.3. Can chronyd keep the system clock a fixed offset away from real time?
+
+Yes. Starting from version 3.0, an offset can be specified by the offset option
+for all time sources in the chrony.conf file.
+
+6.4. What happens if the network connection is dropped without using chronyc's
+offline command first?
+
+chronyd will keep trying to access the sources that it thinks are online, and
+it will take longer before new measurements are actually made and the clock is
+corrected when the network is connected again. If the sources were set to
+offline, chronyd would make new measurements immediately after issuing the
+online command.
+
+Unless the network connection lasts only few minutes (less than the maximum
+polling interval), the delay is usually not a problem, and it might be
+acceptable to keep all sources online all the time.
+
+6.5. Why is an offset measured between two computers synchronised to each
+another?
+
+When two computers are synchronised to each other using the client/server or
+symmetric NTP mode, there is an expectation that NTP measurements between the
+two computers made on both ends show an average offset close to zero.
+
+With chronyd that can be expected only when the interleaved mode is enabled by
+the xleave option. Otherwise, chronyd will use different transmit timestamps
+(e.g. daemon timestamp vs kernel timestamp) for serving time and
+synchronisation of its own clock, which will cause the other computer to
+measure a significant offset.
+
+7. Operation
+
+7.1. What clocks does chronyd use?
+
+There are several different clocks used by chronyd:
+
+  o System clock: software clock maintained by the kernel. It is the main clock
+    used by applications running on the computer. It is synchronised by chronyd
+    to its NTP clock, unless started with the -x option.
+
+  o NTP clock: software clock (virtual) based on the system clock and internal
+    to chronyd. It keeps the best estimate of the true time according to the
+    configured time sources, which is served to NTP clients unless time
+    smoothing is enabled by the smoothtime directive. The System time value in
+    the tracking report is the current offset between the system and NTP clock.
+
+  o Real-time clock (RTC): hardware clock keeping time even when the computer
+    is turned off. It is used by the kernel to initialise the system clock on
+    boot and also by chronyd to compensate for its measured drift if configured
+    with the rtcfile directive and started with the -s option. The clock can be
+    kept accurate only by stepping enabled by the rtcsync or rtcautotrim
+    directive.
+
+  o Reference clock: hardware clock used as a time source. It is specified by
+    the refclock directive.
+
+  o NIC clock (also known as PTP hardware clock): hardware clock timestamping
+    packets received and transmitted by a network device specified by the
+    hwtimestamp directive. The clock is expected to be running free. It is not
+    synchronised by chronyd. Its offset is tracked relative to the NTP clock in
+    order to convert the hardware timestamps.
+
+8. Operating systems
+
+8.1. Does chrony support Windows?
+
+No. The chronyc program (the command-line client used for configuring chronyd
+while it is running) has been successfully built and run under Cygwin in the
+past. chronyd is not portable, because part of it is very system-dependent. It
+needs adapting to work with Windows' equivalent of the adjtimex() call, and it
+needs to be made to work as a service.
+
+8.2. Are there any plans to support Windows?
+
+We have no plans to do this. Anyone is welcome to pick this work up and
+contribute it back to the project.
+
+Last updated 2023-08-09 15:20:55 +0200
diff --git a/INSTALL b/INSTALL
new file mode 100644
index 0000000..6c542bd
--- /dev/null
+++ b/INSTALL
@@ -0,0 +1,165 @@
+Installation
+
+The software is distributed as source code which has to be compiled. The source
+code is supplied in the form of a gzipped tar file, which unpacks to a
+subdirectory identifying the name and version of the program.
+
+A C compiler (e.g. gcc or clang) and GNU Make are needed to build chrony. The
+following libraries with their development files, and programs, are needed to
+enable optional features:
+
+  o pkg-config: detection of development libraries
+
+  o Nettle, GnuTLS, NSS, or LibTomCrypt: secure hash functions (SECHASH)
+
+  o libcap: dropping root privileges on Linux (DROPROOT)
+
+  o libseccomp: system call filter on Linux (SCFILTER)
+
+  o GnuTLS and Nettle: Network Time Security (NTS)
+
+  o Editline: line editing in chronyc (READLINE)
+
+  o timepps.h header: PPS reference clock
+
+  o Asciidoctor: documentation in HTML format
+
+  o Bash: test suite
+
+The following programs are needed when building chrony from the git repository
+instead of a released tar file:
+
+  o Asciidoctor: manual pages
+
+  o Bison: parser for chronyc settime command
+
+After unpacking the source code, change directory into it, and type
+
+./configure
+
+This is a shell script that automatically determines the system type. There is
+an optional parameter --prefix, which indicates the directory tree where the
+software should be installed. For example,
+
+./configure --prefix=/opt/free
+
+will install the chronyd daemon into /opt/free/sbin and the chronyc control
+program into /opt/free/bin. The default value for the prefix is /usr/local.
+
+The configure script assumes you want to use gcc as your compiler. If you want
+to use a different compiler, you can configure this way:
+
+CC=cc ./configure --prefix=/opt/free
+
+for Bourne-family shells, or
+
+setenv CC cc
+setenv CFLAGS -O
+./configure --prefix=/opt/free
+
+for C-family shells.
+
+If the software cannot (yet) be built on your system, an error message will be
+shown. Otherwise, Makefile will be generated.
+
+On Linux, if development files for the libcap library are available, chronyd
+will be built with support for dropping root privileges. On other systems no
+extra library is needed. The default user which chronyd should run as can be
+specified with the --with-user option of the configure script.
+
+If development files for the POSIX threads library are available, chronyd will
+be built with support for asynchronous resolving of hostnames specified in the
+server, peer, and pool directives. This allows chronyd operating as a server to
+respond to client requests when resolving a hostname. If you don't want to
+enable the support, specify the --disable-asyncdns flag to configure.
+
+If development files for the Nettle, NSS, or libtomcrypt library are available,
+chronyd will be built with support for other cryptographic hash functions than
+MD5, which can be used for NTP authentication with a symmetric key. If you
+don't want to enable the support, specify the --disable-sechash flag to
+configure.
+
+If development files for the editline library are available, chronyc will be
+built with line editing support. If you don't want this, specify the
+--disable-readline flag to configure.
+
+If a timepps.h header is available (e.g. from the LinuxPPS project), chronyd
+will be built with PPS API reference clock driver. If the header is installed
+in a location that isn't normally searched by the compiler, you can add it to
+the searched locations by setting the CPPFLAGS variable to -I/path/to/timepps.
+
+The --help option can be specified to configure to print all options supported
+by the script.
+
+Now type
+
+make
+
+to build the programs.
+
+If you want to build the manual in HTML, type
+
+make docs
+
+Once the programs have been successfully compiled, they need to be installed in
+their target locations. This step normally needs to be performed by the
+superuser, and requires the following command to be entered.
+
+make install
+
+This will install the binaries and man pages.
+
+To install the HTML version of the manual, enter the command
+
+make install-docs
+
+Now that the software is successfully installed, the next step is to set up a
+configuration file. The default location of the file is /etc/chrony.conf.
+Several examples of configuration with comments are included in the examples
+directory. Suppose you want to use public NTP servers from the pool.ntp.org
+project as your time reference. A minimal useful configuration file could be
+
+pool pool.ntp.org iburst
+makestep 1.0 3
+rtcsync
+
+Then, chronyd can be run. For security reasons, it's recommended to create an
+unprivileged user for chronyd and specify it with the -u command-line option or
+the user directive in the configuration file, or set the default user with the
+--with-user configure option before building.
+
+Support for system call filtering
+
+chronyd can be built with support for the Linux secure computing (seccomp)
+facility. This requires development files for the libseccomp library and the
+--enable-scfilter option specified to configure. The -F option of chronyd will
+enable a system call filter, which should significantly reduce the kernel
+attack surface and possibly prevent kernel exploits from chronyd if it is
+compromised.
+
+Extra options for package builders
+
+The configure and make procedures have some extra options that may be useful if
+you are building a distribution package for chrony.
+
+The --mandir=DIR option to configure specifies an installation directory for
+the man pages. This overrides the man subdirectory of the argument to the
+--prefix option.
+
+./configure --prefix=/usr --mandir=/usr/share/man
+
+to set both options together.
+
+The final option is the DESTDIR option to the make command. For example, you
+could use the commands
+
+./configure --prefix=/usr --mandir=/usr/share/man
+make all docs
+make install DESTDIR=./tmp
+cd tmp
+tar cvf - . | gzip -9 > chrony.tar.gz
+
+to build a package. When untarred within the root directory, this will install
+the files to the intended final locations.
+
+Last updated 2023-08-09 15:20:55 +0200
diff --git a/Makefile.in b/Makefile.in
new file mode 100644
index 0000000..101e0c6
--- /dev/null
+++ b/Makefile.in
@@ -0,0 +1,143 @@
+##################################################
+#
+# chronyd/chronyc - Programs for keeping computer clocks accurate.
+# 
+# Copyright (C) Richard P. Curnow  1997-2003
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of version 2 of the GNU General Public License as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# =======================================================================
+#
+# Makefile template
+
+SYSCONFDIR = @SYSCONFDIR@
+BINDIR = @BINDIR@
+SBINDIR = @SBINDIR@
+LOCALSTATEDIR = @LOCALSTATEDIR@
+CHRONYVARDIR = @CHRONYVARDIR@
+DESTDIR =
+
+CC = @CC@
+CFLAGS = @CFLAGS@
+CPPFLAGS = @CPPFLAGS@
+LDFLAGS = @LDFLAGS@
+
+GETDATE_CFLAGS = @GETDATE_CFLAGS@
+
+EXTRA_OBJS = @EXTRA_OBJS@
+
+OBJS = array.o cmdparse.o conf.o local.o logging.o main.o memory.o quantiles.o \
+       reference.o regress.o rtc.o samplefilt.o sched.o socket.o sources.o sourcestats.o \
+       stubs.o smooth.o sys.o sys_null.o tempcomp.o util.o $(EXTRA_OBJS)
+
+EXTRA_CLI_OBJS = @EXTRA_CLI_OBJS@
+
+CLI_OBJS = array.o client.o cmdparse.o getdate.o memory.o nameserv.o \
+           pktlength.o socket.o util.o $(EXTRA_CLI_OBJS)
+
+ALL_OBJS = $(OBJS) $(CLI_OBJS)
+
+LIBS = @LIBS@
+EXTRA_LIBS = @EXTRA_LIBS@
+EXTRA_CLI_LIBS = @EXTRA_CLI_LIBS@
+
+# Until we have a main procedure we can link, just build object files
+# to test compilation
+
+all : chronyd chronyc
+
+chronyd : $(OBJS)
+	$(CC) $(CFLAGS) -o chronyd $(OBJS) $(LDFLAGS) $(LIBS) $(EXTRA_LIBS)
+
+chronyc : $(CLI_OBJS)
+	$(CC) $(CFLAGS) -o chronyc $(CLI_OBJS) $(LDFLAGS) $(LIBS) $(EXTRA_CLI_LIBS)
+
+getdate.o: CFLAGS += $(GETDATE_CFLAGS)
+
+distclean : clean
+	$(MAKE) -C doc distclean
+	$(MAKE) -C test/unit distclean
+	-rm -f .DS_Store
+	-rm -f Makefile config.h config.log
+
+clean :
+	$(MAKE) -C test/unit clean
+	-rm -f *.o *.s chronyc chronyd core.* *~
+	-rm -f *.gcda *.gcno
+	-rm -rf .deps
+	-rm -rf *.dSYM
+
+getdate.c : getdate.y
+	bison -o getdate.c getdate.y
+
+# This can be used to force regeneration of getdate.c
+getdate :
+	bison -o getdate.c getdate.y
+
+# For install, don't use the install command, because its switches
+# seem to vary between systems.
+
+install: chronyd chronyc
+	[ -d $(DESTDIR)$(SYSCONFDIR) ] || mkdir -p $(DESTDIR)$(SYSCONFDIR)
+	[ -d $(DESTDIR)$(SBINDIR) ] || mkdir -p $(DESTDIR)$(SBINDIR)
+	[ -d $(DESTDIR)$(BINDIR) ] || mkdir -p $(DESTDIR)$(BINDIR)
+	[ -d $(DESTDIR)$(CHRONYVARDIR) ] || mkdir -p $(DESTDIR)$(CHRONYVARDIR)
+	if [ -f $(DESTDIR)$(SBINDIR)/chronyd ]; then rm -f $(DESTDIR)$(SBINDIR)/chronyd ; fi
+	if [ -f $(DESTDIR)$(BINDIR)/chronyc ]; then rm -f $(DESTDIR)$(BINDIR)/chronyc ; fi
+	cp chronyd $(DESTDIR)$(SBINDIR)/chronyd
+	chmod 755 $(DESTDIR)$(SBINDIR)/chronyd
+	cp chronyc $(DESTDIR)$(BINDIR)/chronyc
+	chmod 755 $(DESTDIR)$(BINDIR)/chronyc
+	$(MAKE) -C doc install
+
+docs :
+	$(MAKE) -C doc docs
+
+install-docs :
+	$(MAKE) -C doc install-docs
+
+%.o : %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
+
+%.s : %.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -S $<
+
+quickcheck : chronyd chronyc
+	$(MAKE) -C test/unit check
+	cd test/simulation && ./run
+	cd test/system && ./run
+
+check : chronyd chronyc
+	$(MAKE) -C test/unit check
+	cd test/simulation && ./run -i 20 -m 2
+	cd test/system && ./run
+
+print-chronyd-objects :
+	@echo $(OBJS)
+
+Makefile : Makefile.in configure
+	@echo
+	@echo Makefile needs to be regenerated, run ./configure
+	@echo
+	@exit 1
+
+.deps:
+	@mkdir .deps
+
+.deps/%.d: %.c | .deps
+	@$(CC) -MM $(CPPFLAGS) -MT '$(<:%.c=%.o) $@' $< -o $@
+
+ifndef NODEPS
+-include $(ALL_OBJS:%.o=.deps/%.d)
+endif
diff --git a/NEWS b/NEWS
new file mode 100644
index 0000000..2e9a743
--- /dev/null
+++ b/NEWS
@@ -0,0 +1,1003 @@
+New in version 4.4
+==================
+
+Enhancements
+------------
+* Add support for AES-GCM-SIV with Nettle >= 3.9 to shorten NTS
+  cookies to avoid some length-specific blocking of NTP on Internet
+* Add support for multiple refclocks using extpps option on one PHC
+* Add maxpoll option to hwtimestamp directive to improve PHC tracking
+  with low packet rates
+* Add hwtstimeout directive to configure timeout for late timestamps
+* Handle late hardware transmit timestamps of NTP requests on all sockets
+* Handle mismatched 32/64-bit time_t in SOCK refclock samples
+* Improve source replacement
+* Log important changes made by command requests (chronyc)
+* Refresh address of NTP sources periodically
+* Request nanosecond kernel RX timestamping on FreeBSD
+* Set DSCP for IPv6 packets
+* Shorten NTS-KE retry interval when network is down
+* Update seccomp filter for musl
+* Warn if loading keys from file with unexpected permissions
+* Warn if source selection fails or falseticker is detected
+* Add selectopts command to modify source-specific selection options
+* Add timestamp sources to serverstats report and make its fields 64-bit
+* Add -e option to chronyc to indicate end of response
+
+New in version 4.3
+==================
+
+Enhancements
+------------
+* Add local option to refclock directive to stabilise system clock
+  with more stable free-running clock (e.g. TCXO, OCXO)
+* Add maxdelayquant option to server/pool/peer directive to replace
+  maxdelaydevratio filter with long-term quantile-based filtering
+* Add selection option to log directive
+* Allow external PPS in PHC refclock without configurable pin
+* Don't accept first interleaved response to minimise error in delay
+* Don't use arc4random on Linux to avoid server performance loss
+* Improve filter option to better handle missing NTP samples
+* Improve stability with hardware timestamping and PHC refclock
+* Update seccomp filter
+
+Bug fixes
+---------
+* Fix waitsync command to reconnect when not getting response
+
+New in version 4.2
+==================
+
+Enhancements
+------------
+* Add support for NTPv4 extension field improving synchronisation
+  stability and resolution of root delay and dispersion (experimental)
+* Add support for NTP over PTP (experimental)
+* Add support for AES-CMAC and hash functions in GnuTLS
+* Improve server interleaved mode to be more reliable and support
+  multiple clients behind NAT
+* Update seccomp filter
+* Add statistics about interleaved mode to serverstats report
+
+Bug fixes
+---------
+* Fix RTC support with 64-bit time_t on 32-bit Linux
+* Fix seccomp filter to work correctly with bind*device directives
+* Suppress kernel adjustments of system clock (dosynctodr) on illumos
+
+Other changes
+-------------
+* Switch Solaris support to illumos
+
+New in version 4.1
+==================
+
+Enhancements
+------------
+* Add support for NTS servers specified by IP address (matching
+  Subject Alternative Name in server certificate)
+* Add source-specific configuration of trusted certificates
+* Allow multiple files and directories with trusted certificates
+* Allow multiple pairs of server keys and certificates
+* Add copy option to server/pool directive
+* Increase PPS lock limit to 40% of pulse interval
+* Perform source selection immediately after loading dump files
+* Reload dump files for addresses negotiated by NTS-KE server
+* Update seccomp filter and add less restrictive level
+* Restart ongoing name resolution on online command
+
+Bug fixes
+---------
+* Fix responding to IPv4 command requests on FreeBSD
+* Fix dump files to not include uncorrected offset
+* Fix initstepslew to accept time from own NTP clients
+* Reset NTP address and port when no longer negotiated by NTS-KE server
+
+New in version 4.0
+==================
+
+Enhancements
+------------
+* Add support for Network Time Security (NTS) authentication
+* Add support for AES-CMAC keys (AES128, AES256) with Nettle
+* Add authselectmode directive to control selection of unauthenticated sources
+* Add binddevice, bindacqdevice, bindcmddevice directives
+* Add confdir directive to better support fragmented configuration
+* Add sourcedir directive and "reload sources" command to support dynamic
+  NTP sources specified in files
+* Add clockprecision directive
+* Add dscp directive to set Differentiated Services Code Point (DSCP)
+* Add -L option to limit log messages by severity
+* Add -p option to print whole configuration with included files
+* Add -U option to allow start under non-root user
+* Allow maxsamples to be set to 1 for faster update with -q/-Q option
+* Avoid replacing NTP sources with sources that have unreachable address
+* Improve pools to repeat name resolution to get "maxsources" sources
+* Improve source selection with trusted sources
+* Improve NTP loop test to prevent synchronisation to itself
+* Repeat iburst when NTP source is switched from offline state to online
+* Update clock synchronisation status and leap status more frequently
+* Update seccomp filter
+* Add "add pool" command
+* Add "reset sources" command to drop all measurements
+* Add authdata command to print details about NTP authentication
+* Add selectdata command to print details about source selection
+* Add -N option and sourcename command to print original names of sources
+* Add -a option to some commands to print also unresolved sources
+* Add -k, -p, -r options to clients command to select, limit, reset data
+
+Bug fixes
+---------
+* Don't set interface for NTP responses to allow asymmetric routing
+* Handle RTCs that don't support interrupts
+* Respond to command requests with correct address on multihomed hosts
+
+Removed features
+----------------
+* Drop support for RIPEMD keys (RMD128, RMD160, RMD256, RMD320)
+* Drop support for long (non-standard) MACs in NTPv4 packets (chrony 2.x
+  clients using non-MD5/SHA1 keys need to use option "version 3")
+* Drop support for line editing with GNU Readline
+
+New in version 3.5.1
+====================
+
+Security fixes
+--------------
+* Create new file when writing pidfile (CVE-2020-14367)
+
+New in version 3.5
+==================
+
+Enhancements
+------------
+* Add support for more accurate reading of PHC on Linux 5.0
+* Add support for hardware timestamping on interfaces with read-only
+  timestamping configuration
+* Add support for memory locking and real-time priority on FreeBSD,
+  NetBSD, Solaris
+* Update seccomp filter to work on more architectures
+* Validate refclock driver options
+
+Bug fixes
+---------
+* Fix bindaddress directive on FreeBSD
+* Fix transposition of hardware RX timestamp on Linux 4.13 and later
+* Fix building on non-glibc systems
+
+New in version 3.4
+==================
+
+Enhancements
+------------
+* Add filter option to server/pool/peer directive
+* Add minsamples and maxsamples options to hwtimestamp directive
+* Add support for faster frequency adjustments in Linux 4.19
+* Change default pidfile to /var/run/chrony/chronyd.pid to allow
+  chronyd without root privileges to remove it on exit
+* Disable sub-second polling intervals for distant NTP sources
+* Extend range of supported sub-second polling intervals
+* Get/set IPv4 destination/source address of NTP packets on FreeBSD
+* Make burst options and command useful with short polling intervals
+* Modify auto_offline option to activate when sending request failed
+* Respond from interface that received NTP request if possible
+* Add onoffline command to switch between online and offline state
+  according to current system network configuration
+* Improve example NetworkManager dispatcher script
+
+Bug fixes
+---------
+* Avoid waiting in Linux getrandom system call
+* Fix PPS support on FreeBSD and NetBSD
+
+New in version 3.3
+==================
+
+Enhancements
+------------
+* Add burst option to server/pool directive
+* Add stratum and tai options to refclock directive
+* Add support for Nettle crypto library
+* Add workaround for missing kernel receive timestamps on Linux
+* Wait for late hardware transmit timestamps
+* Improve source selection with unreachable sources
+* Improve protection against replay attacks on symmetric mode
+* Allow PHC refclock to use socket in /var/run/chrony
+* Add shutdown command to stop chronyd
+* Simplify format of response to manual list command
+* Improve handling of unknown responses in chronyc
+
+Bug fixes
+---------
+* Respond to NTPv1 client requests with zero mode
+* Fix -x option to not require CAP_SYS_TIME under non-root user
+* Fix acquisitionport directive to work with privilege separation
+* Fix handling of socket errors on Linux to avoid high CPU usage
+* Fix chronyc to not get stuck in infinite loop after clock step
+
+New in version 3.2
+==================
+
+Enhancements
+------------
+* Improve stability with NTP sources and reference clocks
+* Improve stability with hardware timestamping
+* Improve support for NTP interleaved modes
+* Control frequency of system clock on macOS 10.13 and later
+* Set TAI-UTC offset of system clock with leapsectz directive
+* Minimise data in client requests to improve privacy
+* Allow transmit-only hardware timestamping
+* Add support for new timestamping options introduced in Linux 4.13
+* Add root delay, root dispersion and maximum error to tracking log
+* Add mindelay and asymmetry options to server/peer/pool directive
+* Add extpps option to PHC refclock to timestamp external PPS signal
+* Add pps option to refclock directive to treat any refclock as PPS
+* Add width option to refclock directive to filter wrong pulse edges
+* Add rxfilter option to hwtimestamp directive
+* Add -x option to disable control of system clock
+* Add -l option to log to specified file instead of syslog
+* Allow multiple command-line options to be specified together
+* Allow starting without root privileges with -Q option
+* Update seccomp filter for new glibc versions
+* Dump history on exit by default with dumpdir directive
+* Use hardening compiler options by default
+
+Bug fixes
+---------
+* Don't drop PHC samples with low-resolution system clock
+* Ignore outliers in PHC tracking, RTC tracking, manual input
+* Increase polling interval when peer is not responding
+* Exit with error message when include directive fails
+* Don't allow slash after hostname in allow/deny directive/command
+* Try to connect to all addresses in chronyc before giving up
+
+New in version 3.1
+==================
+
+Enhancements
+------------
+* Add support for precise cross timestamping of PHC on Linux
+* Add minpoll, precision, nocrossts options to hwtimestamp directive
+* Add rawmeasurements option to log directive and modify measurements
+  option to log only valid measurements from synchronised sources
+* Allow sub-second polling interval with NTP sources
+
+Bug fixes
+---------
+* Fix time smoothing in interleaved mode
+
+New in version 3.0
+==================
+
+Enhancements
+------------
+* Add support for software and hardware timestamping on Linux
+* Add support for client/server and symmetric interleaved modes
+* Add support for MS-SNTP authentication in Samba
+* Add support for truncated MACs in NTPv4 packets
+* Estimate and correct for asymmetric network jitter
+* Increase default minsamples and polltarget to improve stability
+  with very low jitter
+* Add maxjitter directive to limit source selection by jitter
+* Add offset option to server/pool/peer directive
+* Add maxlockage option to refclock directive
+* Add -t option to chronyd to exit after specified time
+* Add partial protection against replay attacks on symmetric mode
+* Don't reset polling interval when switching sources to online state
+* Allow rate limiting with very short intervals
+* Improve maximum server throughput on Linux and NetBSD
+* Remove dump files after start
+* Add tab-completion to chronyc with libedit/readline
+* Add ntpdata command to print details about NTP measurements
+* Allow all source options to be set in add server/peer command
+* Indicate truncated addresses/hostnames in chronyc output
+* Print reference IDs as hexadecimal numbers to avoid confusion with
+  IPv4 addresses
+
+Bug fixes
+---------
+* Fix crash with disabled asynchronous name resolving
+
+New in version 2.4.1
+====================
+
+Bug fixes
+---------
+* Fix processing of kernel timestamps on non-Linux systems
+* Fix crash with smoothtime directive
+* Fix validation of refclock sample times
+* Fix parsing of refclock directive
+
+New in version 2.4
+==================
+
+Enhancements
+------------
+* Add orphan option to local directive for orphan mode compatible with ntpd
+* Add distance option to local directive to set activation threshold
+  (1 second by default)
+* Add maxdrift directive to set maximum allowed drift of system clock
+* Try to replace NTP sources exceeding maximum distance
+* Randomise source replacement to avoid getting stuck with bad sources
+* Randomise selection of sources from pools on start
+* Ignore reference timestamp as ntpd doesn't always set it correctly
+* Modify tracking report to use same values as seen by NTP clients
+* Add -c option to chronyc to write reports in CSV format
+* Provide detailed manual pages
+
+Bug fixes
+---------
+* Fix SOCK refclock to work correctly when not specified as last refclock
+* Fix initstepslew and -q/-Q options to accept time from own NTP clients
+* Fix authentication with keys using 512-bit hash functions
+* Fix crash on exit when multiple signals are received
+* Fix conversion of very small floating-point numbers in command packets
+
+Removed features
+----------------
+* Drop documentation in Texinfo format
+
+New in version 2.3
+==================
+
+Enhancements
+------------
+* Add support for NTP and command response rate limiting
+* Add support for dropping root privileges on Mac OS X, FreeBSD, Solaris
+* Add require and trust options for source selection
+* Enable logchange by default (1 second threshold)
+* Set RTC on Mac OS X with rtcsync directive
+* Allow binding to NTP port after dropping root privileges on NetBSD
+* Drop CAP_NET_BIND_SERVICE capability on Linux when NTP port is disabled
+* Resolve names in separate process when seccomp filter is enabled
+* Replace old records in client log when memory limit is reached
+* Don't reveal local time and synchronisation state in client packets
+* Don't keep client sockets open for longer than necessary
+* Ignore poll in KoD RATE packets as ntpd doesn't always set it correctly
+* Warn when using keys shorter than 80 bits
+* Add keygen command to generate random keys easily
+* Add serverstats command to report NTP and command packet statistics
+
+Bug fixes
+---------
+* Fix clock correction after making step on Mac OS X
+* Fix building on Solaris
+
+New in version 2.2.1
+====================
+
+Security fixes
+--------------
+* Restrict authentication of NTP server/peer to specified key (CVE-2016-1567)
+
+New in version 2.2
+==================
+
+Enhancements
+------------
+* Add support for configuration and monitoring over Unix domain socket
+  (accessible by root or chrony user when root privileges are dropped)
+* Add support for system call filtering with seccomp on Linux (experimental)
+* Add support for dropping root privileges on NetBSD
+* Control frequency of system clock on FreeBSD, NetBSD, Solaris
+* Add system leap second handling mode on FreeBSD, NetBSD, Solaris
+* Add dynamic drift removal on Mac OS X
+* Add support for setting real-time priority on Mac OS X
+* Add maxdistance directive to limit source selection by root distance
+  (3 seconds by default)
+* Add refresh command to get new addresses of NTP sources
+* Allow wildcard patterns in include directive
+* Restore time from driftfile with -s option if later than RTC time
+* Add configure option to set default hwclockfile
+* Add -d option to chronyc to enable debug messages
+* Allow multiple addresses to be specified for chronyc with -h option
+  and reconnect when no valid reply is received
+* Make check interval in waitsync command configurable
+
+Bug fixes
+---------
+* Fix building on NetBSD, Solaris
+* Restore time from driftfile with -s option if reading RTC failed
+
+Removed features
+----------------
+* Drop support for authentication with command key (run-time configuration
+  is now allowed only for local users that can access the Unix domain socket)
+
+New in version 2.1.1
+====================
+
+Bug fixes
+---------
+* Fix clock stepping by integer number of seconds on Linux
+
+New in version 2.1
+==================
+
+Enhancements
+------------
+* Add support for Mac OS X
+* Try to replace unreachable and falseticker servers/peers specified
+  by name like pool sources
+* Add leaponly option to smoothtime directive to allow synchronised
+  leap smear between multiple servers
+* Use specific reference ID when smoothing served time
+* Add smoothing command to report time smoothing status
+* Add smoothtime command to activate or reset time smoothing
+
+Bug fixes
+---------
+* Fix crash in source selection with preferred sources
+* Fix resetting of time smoothing
+* Include packet precision in peer dispersion
+* Fix crash in chronyc on invalid command syntax
+
+New in version 2.0
+==================
+
+Enhancements
+------------
+* Update to NTP version 4 (RFC 5905)
+* Add pool directive to specify pool of NTP servers
+* Add leapsecmode directive to select how to correct clock for leap second
+* Add smoothtime directive to smooth served time and enable leap smear
+* Add minsources directive to set required number of selectable sources
+* Add minsamples and maxsamples options for all sources
+* Add tempcomp configuration with list of points
+* Allow unlimited number of NTP sources, refclocks and keys
+* Allow unreachable sources to remain selected
+* Improve source selection
+* Handle offline sources as unreachable
+* Open NTP server port only when necessary (client access is allowed by
+  allow directive/command or peer/broadcast is configured)
+* Change default bindcmdaddress to loopback address
+* Change default maxdelay to 3 seconds
+* Change default stratumweight to 0.001
+* Update adjtimex synchronisation status
+* Use system headers for adjtimex
+* Check for memory allocation errors
+* Reduce memory usage
+* Add configure options to compile without NTP, cmdmon, refclock support
+* Extend makestep command to set automatic clock stepping
+
+Bug fixes
+---------
+* Add sanity checks for time and frequency offset
+* Don't report synchronised status during leap second
+* Don't combine reference clocks with close NTP sources
+* Fix accepting requests from configured sources
+* Fix initial fallback drift setting
+
+New in version 1.31.1
+=====================
+
+Security fixes
+--------------
+* Protect authenticated symmetric NTP associations against DoS attacks
+  (CVE-2015-1853)
+* Fix access configuration with subnet size indivisible by 4 (CVE-2015-1821)
+* Fix initialization of reply slots for authenticated commands (CVE-2015-1822)
+
+New in version 1.31
+===================
+
+Enhancements
+------------
+* Support operation in other NTP eras (next era begins in 2036),
+  NTP time is mapped to [-50, +86] years around build date by default
+* Restore time from driftfile with -s when RTC is missing/unsupported
+* Close connected client sockets when not waiting for reply
+* Use one client socket with random port when acquisitionport is 0
+* Use NTP packets instead of UDP echo for presend
+* Don't adjust polling interval when sending fails
+* Allow binding to addresses that don't exist yet
+* Ignore measurements around leap second
+* Improve detection of unexpected time jumps
+* Include example of logrotate configuration, systemd services and
+  NetworkManager dispatcher script
+
+Bug fixes
+---------
+* Reconnect client sockets for each request to follow changes
+  in network configuration automatically
+* Restart timer when polling interval is changed on reset
+
+New in version 1.30
+===================
+
+Enhancements
+------------
+* Add asynchronous name resolving with POSIX threads
+* Add PTP hardware clock (PHC) refclock driver
+* Add new generic clock driver to slew by adjusting frequency only
+  (without kernel PLL or adjtime) and use it on Linux
+* Add rtcautotrim directive to trim RTC automatically
+* Add hwclockfile directive to share RTC LOCAL/UTC setting with hwclock
+* Add maxslewrate directive to set maximum allowed slew rate
+* Add maxdispersion option for refclocks
+* Add -q/-Q options to set clock/print offset once and exit
+* Allow directives to be specified on chronyd command line
+* Replace frequency scaling in Linux driver with retaining of tick
+* Try to detect unexpected forward time jumps and reset state
+* Exit with non-zero code when maxchange limit is reached
+* Improve makestep to not start and stop slew unnecessarily
+* Change default corrtimeratio to 3.0 to improve frequency accuracy
+* Announce leap second only on last day of June and December
+* Use separate connected client sockets for each NTP server
+* Remove separate NTP implementation used for initstepslew
+* Limit maximum minpoll set by KoD RATE to default maxpoll
+* Don't send NTP requests with unknown key
+* Print warning when source is added with unknown key
+* Take leap second in PPS refclock from locked source
+* Make reading of RTC for initial trim more reliable
+* Don't create cmdmon sockets when cmdport is 0
+* Add configure option to set default user to drop root privileges
+* Add configure option to compile with debug messages
+* Print debug messages when -d is used more than once
+* Change format of messages written to terminal with -d
+* Write fatal messages also to stderr with -n
+* Use IP_RECVERR socket option in chronyc to not wait unnecessarily
+* Shorten default chronyc timeout for localhost
+* Change default hostname in chronyc from localhost to 127.0.0.1
+* Print error message on invalid syntax with all chronyc commands
+* Include simulation test suite using clknetsim
+
+Bug fixes
+---------
+* Fix crash when selecting with multiple preferred sources
+* Fix frequency calculation with large frequency offsets
+* Fix code writing drift and RTC files to compile correctly
+* Fix -4/-6 options in chronyc to not reset hostname set by -h
+* Fix refclock sample validation with sub-second polling interval
+* Set stratum correctly with non-PPS SOCK refclock and local stratum
+* Modify dispersion accounting in refclocks to prevent PPS getting
+  stuck with large dispersion and not accepting new samples
+
+New in version 1.29.1
+=====================
+
+Security fixes
+--------------
+* Modify chronyc protocol to prevent amplification attacks (CVE-2014-0021)
+  (incompatible with previous protocol version, chronyc supports both)
+
+New in version 1.29
+===================
+
+Security fixes
+--------------
+* Fix crash when processing crafted commands (CVE-2012-4502)
+  (possible with IP addresses allowed by cmdallow and localhost)
+* Don't send uninitialized data in SUBNETS_ACCESSED and CLIENT_ACCESSES
+  replies (CVE-2012-4503) (not used by chronyc)
+
+Other changes
+-------------
+* Drop support for SUBNETS_ACCESSED and CLIENT_ACCESSES commands
+
+New in version 1.28
+===================
+
+* Combine sources to improve accuracy
+* Make config and command parser strict
+* Add -a option to chronyc to authenticate automatically
+* Add -R option to ignore initstepslew and makestep directives
+* Add generatecommandkey, minsamples, maxsamples and user directives
+* Improve compatibility with NTPv1 and NTPv2 clients
+* Create sockets only in selected family with -4/-6 option
+* Treat address bind errors as non-fatal
+* Extend tracking log
+* Accept float values as initstepslew threshold
+* Allow hostnames in offline, online and burst commands
+* Fix and improve peer polling
+* Fix crash in config parsing with too many servers
+* Fix crash with duplicated initstepslew address
+* Fix delta calculation with extreme frequency offsets
+* Set local stratum correctly
+* Remove unnecessary adjtimex calls
+* Set paths in documentation by configure
+* Update chrony.spec
+
+New in version 1.27
+===================
+
+* Support for stronger keys via NSS or libtomcrypt library
+* Support reading leap second data from tz database
+* Support for precise clock stepping on Linux
+* Support for nanoseconds in SHM refclock
+* Make offset corrections smoother on Linux
+* Make transmit timestamps random below clock precision
+* Add corrtimeratio and maxchange directives
+* Extend tracking, sources and activity reports
+* Wait in foreground process until daemon is fully initialized
+* Fix crash with slow name resolving
+* Fix iburst with jittery sources
+* Fix offset stored in rtc data right after trimrtc
+* Fix crash and hang with RTC or manual samples
+* Don't use readonly adjtime on Linux kernels before 2.6.28 
+* Changed chronyc protocol, incompatible with older versions
+
+New in version 1.26
+===================
+
+* Add compatibility with Linux 3.0 and later
+* Use proper source address in NTP replies on multihomed IPv6 hosts
+* Accept NTP packets with versions 4, 3 and 2
+* Cope with unexpected backward time jumps
+* Don't reset kernel frequency on start without drift file
+* Retry on permanent DNS error by default
+* Add waitsync command
+
+New in version 1.25
+===================
+
+* Improve accuracy with NTP sources
+* Improve accuracy with reference clocks
+* Improve polling interval adjustment
+* Improve stability with temporary asymmetric delays
+* Improve source selection
+* Improve initial synchronisation
+* Add delayed server name resolving
+* Add temperature compensation
+* Add nanosecond slewing to Linux driver
+* Add fallback drifts
+* Add iburst, minstratum, maxdelaydevratio, polltarget,
+  prefer, noselect options
+* Add rtcsync directive to enable Linux 11-minute mode
+* Add reselectdist, stratumweight, logbanner, maxclockerror,
+  include directives
+* Add -n option to not detach daemon from terminal
+* Fix pidfile directive
+* Fix name resolving with disabled IPv6 support
+* Fix reloading sample histories with reference clocks
+* Fix crash with auto_offline option
+* Fix online command on auto_offline sources
+* Fix file descriptor leaks
+* Increase burst polling interval and stop on KoD RATE
+* Set maxupdateskew to 1000 ppm by default
+* Require password for clients command
+* Update drift file at most once per hour
+* Use system headers for Linux RTC support
+* Reduce default chronyc timeout and make it configurable
+* Avoid large values in chronyc sources and sourcestats output
+* Add reselect command to force reselecting best source
+* Add -m option to allow multiple commands on command line
+
+New in version 1.24
+===================
+
+Security fixes
+--------------
+* Don't reply to invalid cmdmon packets (CVE-2010-0292)
+* Limit client log memory size (CVE-2010-0293)
+* Limit rate of syslog messages (CVE-2010-0294)
+
+Bug fixes/Enhancements
+----------------------
+* Support for reference clocks (SHM, SOCK, PPS drivers)
+* IPv6 support
+* Linux capabilities support (to drop root privileges)
+* Memory locking support on Linux
+* Real-time scheduler support on Linux
+* Leap second support on Linux
+* Support for editline library
+* Support for new Linux readonly adjtime
+* NTP client support for KoD RATE
+* Read kernel timestamps for received NTP packets
+* Reply to NTP requests with correct address on multihomed hosts
+* Retry name resolving after temporary failure
+* Fix makestep command, make it available on all systems
+* Add makestep directive for automatic clock stepping
+* Don't require _bigadj kernel symbol on NetBSD
+* Avoid blocking read in Linux RTC driver
+* Support for Linux on S/390 and PowerPC
+* Fix various bugs on 64-bit systems
+* Fix valgrind errors and compiler warnings
+* Improve configure to support common options and variables
+* Improve status checking and printing in chronyc
+* Return non-zero exit code on errors in chronyc
+* Reduce request timeout in chronyc
+* Print estimated offset in sourcestats
+* Changed chronyc protocol, incompatible with older versions
+
+New in version 1.23
+===================
+
+* Support for MIPS, x86_64, sparc, alpha, arm, FreeBSD
+* Fix serious sign-extension error in handling IP addresses
+* RTC support can be excluded at compile time
+* Make sources gcc-4 compatible
+* Fix various compiler warnings
+* Handle fluctuations in peer distance better.
+* Fixed handling of stratum zero.
+* Fix various problems for 64-bit systems
+* Flush chronyc output streams after each command, to allow it to be driven
+  through pipes
+* Manpage improvements
+
+Version 1.22
+============
+
+This release number was claimed by a release that Mandriva made to patch
+important bugs in 1.21.  The official numbering has jumped to 1.23 as a
+consequence.
+
+New in version 1.21
+===================
+
+* Don't include Linux kernel header files any longer : allows chrony to compile
+  on recent distros.
+* Stop trying to use RTC if continuous streams of error messages would occur
+  (Linux with HPET).
+
+New in version 1.20
+===================
+
+* Many small tidy-ups and security improvements
+* Improve documentation (RTC support in post 2.0 kernels)
+* Remove trailing \n from syslog messages
+* Syslog messages now include IP and port number when packet cannot be sent.
+* Added the "acquisitionport" directive.  (Kalle Olavi Niemitalo)
+* Use uname(2) instead of /proc/version to get kernel version.
+* Merge support for Linux on Alpha
+* Merge support for 64bit architectures
+* Don't link -lm if it's not needed
+* Fix Solaris build (broken by 64bit change)
+* Add detection of Linux 2.5
+* Allow arbitrary value of HZ in Linux kernel
+* Fix for chrony.spec on SuSE (Paul Elliot)
+* Fix handling of initstepslew if no servers are listed (John Hasler)
+* Fix install rule in Makefile if chronyd is in use (Juliusz Chroboczek)
+* Replace sprintf by snprintf to remove risk of buffer overrun (John Hasler)
+* Add --help to configure script
+
+New in version 1.19
+===================
+
+* Auto-detect kernel's timer interrupt rate (so-called 'HZ') when chronyd
+  starts instead of relying on compiled-in value.
+* Fix 2 bugs in function that creates the directory for the log and dump files.
+* Amended webpage URL and contact details.
+* Generate more informative syslog messages before exiting on failed
+  assertions.
+* Fix bugs in clamping code for the tick value used when slewing a large
+  offset.
+* Don't chown files to root during install (should be pointless, and makes RPM
+  building awkward as ordinary user.)
+* Include chrony.spec file for building RPMs
+
+New in version 1.18
+===================
+* Amend homepage and mailing list information to chrony.sunsite.dk
+* Delete pidfile on exit from chronyd.
+* Improvements to readline interface to chronyc
+* Only generate syslog message when synchronisation is initially lost (instead
+  of on every failed synchronisation attempt)
+* Use double fork approach when initialising daemon.
+* More things in contrib directory.
+* New options to help package builders: --infodir/--mandir for configure, and
+  DESTDIR=xxx for make.  (See section 2.2 of chrony.txt for details).
+* Changed the wording of the messages generated by mailonchange and logchange
+  directives.
+
+New in version 1.17
+===================
+* Port to NetBSD
+* Configuration supports Linux on PPC
+* Fix compilation warnings
+* Several documentation improvements
+* Bundled manpages (taken from the 'missing manpages project')
+* Cope with lack of bzero function for Solaris 2.3 systems
+* Store chronyd's pid in a file (default /var/run/chronyd.pid) and check if
+  chronyd may already be running when starting up.  New pidfile directive in
+  configuration file.
+* Any size subnet is now allowed in allow and deny commands.  (Example:
+  6.7.8/20 or 6.7.8.x/20 (any x) mean a 20 bit subnet).
+* The environment variables CC and CFLAGS passed to configure can now be used
+  to select the compiler and optimisation/debug options to use
+* Write syslog messages when chronyd loses synchronisation.
+* Print GPL text when chronyc is run.
+* Add NTP broadcast server capability (new broadcast directive).
+* Add 'auto_offline' option to server/peer (conf file) or add server/peer (via
+  chronyc).
+* Add 'activity' command to chronyc, to report how many servers/peers are
+  currently online/offline.
+* Fix long-standing bug with how the system time quantum was calculated.
+* Include support for systems with HZ!=100 (HZ is the timer interrupt
+  frequency).
+* Include example chrony.conf and chrony.keys files (examples subdirectory).
+* Include support for readline in chronyc.
+
+New in version 1.16.1
+=====================
+* Fix compilation problem on Linux 2.4.13 (spinlock.h / spinlock_t)
+
+New in version 1.16
+===================
+* More informative captions for 'sources' and 'sourcestats' commands in chronyc
+  (use 'sources -v' and 'sourcestats -v' to get them).
+* Correct behaviour for Solaris versions>=2.6 (dosynctodr not required on these
+  versions.)
+* Remove some compiler warnings (Solaris)
+* If last line of keys file doesn't have end-of-line, don't truncate final
+  character of that key.
+* Change timestamp format used in logfiles to make it fully numeric (to aid
+  importing data into spreadsheets etc)
+* Minor documentation updates and improvements.
+
+New in version 1.15
+===================
+* Add contributed change to 'configure' to support Solaris 2.8 on x86
+* Workaround for assertion failure that arises if two received packets occur
+  close together. (Still need to find out why this happens at all.)
+* Hopefully fix problem where fast slewing was incompatible with machines
+  that have a large background drift rate (=> tick value went out of range
+  for adjtimex() on Linux.)
+* Fix rtc_linux.c compile problems with 2.4.x kernel include files.
+* Include support for RTC device not being at /dev/rtc (new rtcdevice directive
+  in configuration file).
+* Include support for restricting network interfaces for commands (new
+  bindcmdaddress directive in configuration file)
+* Fix potential linking fault in pktlength.c (use of CROAK macro replaced by
+  normal assert).
+* Add some material on bug reporting + contributing to the chrony.texi file
+* Made the chrony.texi file "Vim6-friendly" (removed xrefs on @node lines,
+  added folding markers to chapters + sections.)
+* Switched over to GPL for the licence
+
+New in version 1.14
+===================
+* Fix compilation for certain other Linux distributions (including Mandrake
+  7.1)
+
+New in version 1.13
+===================
+* Fixed compilation problems on Redhat/SuSE installations with recent 2.2.x
+  kernels.
+* Minor tidy-ups and documentation enhancements.
+* Add support for Linux 2.4 kernels
+
+New in version 1.12
+===================
+
+* Trial fix for long-standing bug in Linux RTC estimator when system time is
+  slewed.
+* Fix bug in chronyc if -h is specified without a hostname
+* Fixes to logging various error conditions when operating in daemon mode.
+* More stuff under contrib/
+* Changes to README file (e.g. about the new chrony-users mailing list)
+
+New in version 1.11a
+====================
+
+* Minor changes to contact details
+* Minor changes to installation details (chrony subdirectory under doc/)
+
+New in version 1.11
+===================
+
+* Improve robustness of installation procedure
+* Tidy up documenation and contact details
+* Distribute manual as .txt rather than as .ps
+* Add -n option to chronyc to work with numeric IP addresses rather than
+  names.
+* Add material in contrib subdirectory
+* Improve robustness of handling drift file and RTC coefficients file
+* Improve robustness of regression algorithm
+
+New in version 1.1
+==================
+
+Bug fixes
+---------
+
+* Made linear regression more resistant to rounding errors (old one
+  occasionally generated negative variances which made everything go
+  haywire).  Trap infinite or 'not-a-number' values being used to
+  alter system clock to increase robustness further.
+
+Other changes/Enhancements
+--------------------------
+
+* Support for Linux 2.1 and 2.2 kernels
+
+* New command 'makestep' in chronyc to immediately jump the system
+  time to match the NTP estimated time (Linux only) - a response to
+  systems booting an hour wrong after summertime/wintertime changes,
+  due to RTCs running on local time.  Needs extending to Sun driver
+  files too.
+
+* New directives 'logchange' and 'mailonchange' to log to syslog or
+  email to a specific address respectively if chronyd detects a clock
+  offset exceeding a defined threshold.
+
+* Added capability to log all client/peer NTP accesses and command
+  accesses (can be turned off with conf file directive 'noclientlog').
+  Added 'clients' command to chronyc to display this data.
+
+* Improved manual mode to use robust regression rather than 2 point
+  fit.
+
+* Added 'manual list' and 'manual delete' commands to chronyc to
+  allow display of entered timestamps and discretionary deletion of
+  outliers.
+
+* If host goes unsynchronised the dummy IP address 0.0.0.0 is detected
+  to avoid attempting a reverse name lookup (to stop dial on demand IP
+  links from being started)
+
+* Changed chronyc/chronyd protocol so messages are now all variable
+  length.  Saves on network bandwidth particularly for large replies
+  from chronyd to chronyc (to support the clients command).
+
+* Added bindaddress directive to configuration file, to give
+  additional control over limiting which hosts can access the local
+  server.
+
+* Groundwork done for a port to Windows NT to compile with Cygwin
+  toolkit.  chronyc works (to monitor another host).  sys_winnt.c
+  needs finishing to use NT clock control API.  Program structure
+  needs adapting to use Windows NT service functions, so it can be
+  started at boot time.  Hopefully a Windows NT / Cygwin guru with
+  some spare time can take this port over :-)
+
+New in version 1.02
+===================
+
+Bug fixes
+---------
+
+* Fix error messages in chronyc if daemon is not reachable.
+
+* Fix config file problem for 'allow all' and 'deny all' without a
+  trailing machine address.
+
+* Remove fatal failed assertion if command socket cannot be read from
+  in daemon.
+
+* Rewrote timezone handling for Linux real time clock, following
+  various reported problems related to daylight saving.
+
+Other changes/Enhancements
+--------------------------
+
+* Configure script recognizes BSD/386 and uses SunOS 4.1 driver for
+  it.
+
+* Log files now print date as day-month-year rather than as a day
+  number.  Milliseconds removed from timestamps of logged data.
+  Banners included in file to give meanings of columns.
+
+* Only do 1 initial step (followed by a trimming slew) when
+  initialising from RTC on Linux (previously did 2 steps).
+
+New in version 1.01
+===================
+
+Bug fixes
+---------
+
+* Handle timezone of RTC correctly with respect to daylight saving
+  time
+
+* Syntax check the chronyc 'local' command properly
+
+* Fixed assertion failed fault in median finder (used by RTC
+  regression fitting)
+
+Other changes/Enhancements
+--------------------------
+
+* Log selection of new NTP reference source to syslog.
+
+* Don't zero-pad IP address fields
+
+* Add new command to chronyc to allow logfiles to be cycled.
+
+* Extend allow/deny directive syntax in configuration file to so
+  directive can apply to all hosts on the Internet.
+
+* Tidy up printout of timestamps to make it clear they are in UTC
+
+* Make 'configure' check the processor type as well as the operating
+  system.
diff --git a/README b/README
new file mode 100644
index 0000000..99b0239
--- /dev/null
+++ b/README
@@ -0,0 +1,140 @@
+This is the README for chrony.
+
+What is chrony?
+===============
+
+chrony is a versatile implementation of the Network Time Protocol (NTP).
+It can synchronise the system clock with NTP servers, reference clocks
+(e.g. GPS receiver), and manual input using wristwatch and keyboard.
+It can also operate as an NTPv4 (RFC 5905) server and peer to provide
+a time service to other computers in the network.
+
+It is designed to perform well in a wide range of conditions, including
+intermittent network connections, heavily congested networks, changing
+temperatures (ordinary computer clocks are sensitive to temperature),
+and systems that do not run continuosly, or run on a virtual machine.
+
+Typical accuracy between two machines synchronised over the Internet is
+within a few milliseconds; on a LAN, accuracy is typically in tens of
+microseconds.  With hardware timestamping, or a hardware reference clock,
+sub-microsecond accuracy may be possible.
+
+Two programs are included in chrony, chronyd is a daemon that can be
+started at boot time and chronyc is a command-line interface program
+which can be used to monitor chronyd's performance and to change various
+operating parameters whilst it is running.
+
+What will chrony run on?
+========================
+
+The software is known to work on Linux, FreeBSD, NetBSD, macOS and
+illumos.  Closely related systems may work too.  Any other system will
+likely require a porting exercise.
+
+How do I set it up?
+===================
+
+The file INSTALL gives instructions.  On supported systems the
+compilation process should be automatic.  You will need a C compiler,
+e.g. gcc or clang.
+
+What documentation is there?
+============================
+
+The distribution includes manual pages and a document containing
+Frequently Asked Questions (FAQ).
+
+The documentation is also available on the chrony web pages, accessible
+through the URL 
+
+    https://chrony-project.org/
+
+License
+=======
+
+chrony is distributed under the GNU General Public License version 2.
+
+Authors
+=======
+
+Richard P. Curnow <rc@rc0.org.uk>
+Miroslav Lichvar <mlichvar@redhat.com>
+
+Acknowledgements
+================
+
+In writing the chronyd program, extensive use has been made of the NTPv3 (RFC
+1305) and NTPv4 (RFC 5905) specification.  The source code of the xntpd/ntpd
+implementation written by Dennis Fergusson, Lars Mathiesen, David Mills, and
+others has been used to check the details of the protocol.
+
+The following people have provided patches and other major contributions
+to chrony:
+
+Lonnie Abelbeck <lonnie@abelbeck.com>
+Benny Lyne Amorsen <benny@amorsen.dk>
+Andrew Bishop <amb@gedanken.demon.co.uk>
+Vincent Blut <vincent.debian@free.fr>
+Stephan I. Boettcher <stephan@nevis1.columbia.edu>
+David Bohman <debohman@gmail.com>
+Goswin Brederlow <brederlo@informatik.uni-tuebingen.de>
+Leigh Brown <leigh@solinno.co.uk>
+Erik Bryer <ebryer@spots.ab.ca>
+Jonathan Cameron <jic23@cam.ac.uk>
+Bryan Christianson <bryan@whatroute.net>
+Juliusz Chroboczek <jch@pps.jussieu.fr>
+Dan Drown <dan-ntp@drown.org>
+Kamil Dudka <kdudka@redhat.com>
+Christian Ehrhardt <christian.ehrhardt@canonical.com>
+Paul Elliott <pelliott@io.com>
+Robert Fairley <rfairley@redhat.com>
+Stefan R. Filipek <srfilipek@gmail.com>
+Mike Fleetwood <mike@rockover.demon.co.uk>
+Alexander Gretencord <arutha@gmx.de>
+Andrew Griffiths <agriffit@redhat.com>
+Walter Haidinger <walter.haidinger@gmx.at>
+Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de>
+John Hasler <john@dhh.gt.org>
+Tjalling Hattink <t.hattink@fugro.nl>
+Liam Hatton <me@liamhatton.com>
+Holger Hoffstätte <holger@applied-asynchrony.com>
+Jachym Holecek <jakym@volny.cz>
+Håkan Johansson <f96hajo@chalmers.se>
+Jim Knoble <jmknoble@pobox.com>
+Antti Jrvinen <costello@iki.fi>
+Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+Eric Lammerts <eric@lammerts.org>
+Stefan Lucke <stefan@lucke.in-berlin.de>
+Victor Lum <viclum@vanu.com>
+Kevin Lyda <kevin@ie.suberic.net>
+Paul Menzel <paulepanter@users.sourceforge.net>
+Vladimir Michl <vladimir.michl@seznam.cz>
+Victor Moroz <vim@prv.adlum.ru>
+Kalle Olavi Niemitalo  <tosi@stekt.oulu.fi>
+Frank Otto <sandwichmacher@web.de>
+Denny Page <dennypage@me.com>
+Rupesh Patel <rupatel@redhat.com>
+Chris Perl <cperl@janestreet.com>
+Gautier PHILIPPON <gautier.philippon@ensimag.grenoble-inp.fr>
+Andreas Piesk <apiesk@virbus.de>
+Mike Ryan <msr@hsilop.net>
+Baruch Siach <baruch@tkos.co.il>
+Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+Foster Snowhill <forst@forstwoof.ru>
+Andreas Steinmetz <ast@domdv.de>
+NAKAMURA Takumi <takumi@ps.sakura.ne.jp>
+Timo Teras <timo.teras@iki.fi>
+Bill Unruh <unruh@physics.ubc.ca>
+Stephen Wadeley <swadeley@redhat.com>
+Bernhard Weiss <lisnablagh@web.de>
+Wolfgang Weisselberg <weissel@netcologne.de>
+Bernhard M. Wiedemann <bwiedemann@suse.de>
+Joachim Wiedorn <ad_debian@joonet.de>
+Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
+Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
+Michael Witten <mfwitten@gmail.com>
+Doug Woodward <dougw@whistler.com>
+Thomas Zajic <zlatko@zlatko.fdns.net>
+
+Many other people have contributed bug reports and suggestions.  We are sorry
+we cannot identify all of you individually.
diff --git a/addressing.h b/addressing.h
new file mode 100644
index 0000000..3e311fa
--- /dev/null
+++ b/addressing.h
@@ -0,0 +1,67 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Types used for addressing sources etc
+  */
+
+#ifndef GOT_ADDRESSING_H
+#define GOT_ADDRESSING_H
+
+#include "sysincl.h"
+
+/* This type is used to represent an IPv4 address or IPv6 address.
+   Addresses which are not resolved yet can be represented with an ID.
+   All parts are in HOST order, NOT network order. */
+
+#define IPADDR_UNSPEC 0
+#define IPADDR_INET4 1
+#define IPADDR_INET6 2
+#define IPADDR_ID 3
+
+typedef struct {
+  union { 
+    uint32_t in4;
+    uint8_t in6[16];
+    uint32_t id;
+  } addr;
+  uint16_t family;
+  uint16_t _pad;
+} IPAddr;
+
+typedef struct {
+  IPAddr ip_addr;
+  uint16_t port;
+} IPSockAddr;
+
+typedef IPSockAddr NTP_Remote_Address;
+
+#define INVALID_IF_INDEX -1
+
+typedef struct {
+  IPAddr ip_addr;
+  int if_index;
+  int sock_fd;
+} NTP_Local_Address;
+
+#endif /* GOT_ADDRESSING_H */
+
diff --git a/addrfilt.c b/addrfilt.c
new file mode 100644
index 0000000..6208b46
--- /dev/null
+++ b/addrfilt.c
@@ -0,0 +1,405 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997,1998,1999,2000,2001,2002,2005
+ * Copyright (C) Miroslav Lichvar  2009, 2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module provides a set of routines for checking IP addresses
+  against a set of rules and deciding whether they are allowed or
+  disallowed.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "addrfilt.h"
+#include "memory.h"
+
+/* Define the number of bits which are stripped off per level of
+   indirection in the tables */
+#define NBITS 4
+
+/* Define the table size */
+#define TABLE_SIZE (1UL<<NBITS)
+
+typedef enum {DENY, ALLOW, AS_PARENT} State;
+
+typedef struct _TableNode {
+  State state;
+  struct _TableNode *extended;
+} TableNode;
+
+struct ADF_AuthTableInst {
+  TableNode base4;      /* IPv4 node */
+  TableNode base6;      /* IPv6 node */
+};
+
+/* ================================================== */
+
+static void
+split_ip6(IPAddr *ip, uint32_t *dst)
+{
+  int i;
+
+  for (i = 0; i < 4; i++)
+    dst[i] = (uint32_t)ip->addr.in6[i * 4 + 0] << 24 |
+             ip->addr.in6[i * 4 + 1] << 16 |
+             ip->addr.in6[i * 4 + 2] << 8 |
+             ip->addr.in6[i * 4 + 3];
+}
+
+/* ================================================== */
+
+inline static uint32_t
+get_subnet(uint32_t *addr, unsigned int where)
+{
+  int off;
+
+  off = where / 32;
+  where %= 32;
+
+  return (addr[off] >> (32 - NBITS - where)) & ((1UL << NBITS) - 1);
+}
+
+/* ================================================== */
+
+ADF_AuthTable
+ADF_CreateTable(void)
+{
+  ADF_AuthTable result;
+  result = MallocNew(struct ADF_AuthTableInst);
+
+  /* Default is that nothing is allowed */
+  result->base4.state = DENY;
+  result->base4.extended = NULL;
+  result->base6.state = DENY;
+  result->base6.extended = NULL;
+
+  return result;
+}
+
+/* ================================================== */
+/* This function deletes all definitions of child nodes, in effect
+   pruning a whole subnet definition back to a single parent
+   record. */
+static void
+close_node(TableNode *node)
+{
+  int i;
+  TableNode *child_node;
+
+  if (node->extended != NULL) {
+    for (i=0; i<TABLE_SIZE; i++) {
+      child_node = &(node->extended[i]);
+      close_node(child_node);
+    }
+    Free(node->extended);
+    node->extended = NULL;
+  }
+}
+
+
+/* ================================================== */
+/* Allocate the extension field in a node, and set all the children's
+   states to default to that of the node being extended */
+
+static void
+open_node(TableNode *node)
+{
+  int i;
+  TableNode *child_node;
+
+  if (node->extended == NULL) {
+
+    node->extended = MallocArray(struct _TableNode, TABLE_SIZE);
+
+    for (i=0; i<TABLE_SIZE; i++) {
+      child_node = &(node->extended[i]);
+      child_node->state = AS_PARENT;
+      child_node->extended = NULL;
+    }
+  }
+}
+
+/* ================================================== */
+
+static ADF_Status
+set_subnet(TableNode *start_node,
+           uint32_t *ip,
+           int ip_len,
+           int subnet_bits,
+           State new_state,
+           int delete_children)
+{
+  int bits_to_go, bits_consumed;
+  uint32_t subnet;
+  TableNode *node;
+
+  bits_consumed = 0;
+  bits_to_go = subnet_bits;
+  node = start_node;
+
+  if ((subnet_bits < 0) ||
+      (subnet_bits > 32 * ip_len)) {
+
+    return ADF_BADSUBNET;
+
+  } else {
+
+    if ((bits_to_go & (NBITS-1)) == 0) {
+    
+      while (bits_to_go > 0) {
+        subnet = get_subnet(ip, bits_consumed);
+        if (!(node->extended)) {
+          open_node(node);
+        }
+        node = &(node->extended[subnet]);
+        bits_to_go -= NBITS;
+        bits_consumed += NBITS;
+      }
+
+      if (delete_children) {
+        close_node(node);
+      }
+      node->state = new_state;
+
+    } else { /* Have to set multiple entries */
+      int N, i, j;
+      TableNode *this_node;
+
+      while (bits_to_go >= NBITS) {
+        subnet = get_subnet(ip, bits_consumed);
+        if (!(node->extended)) {
+          open_node(node);
+        }
+        node = &(node->extended[subnet]);
+        bits_to_go -= NBITS;
+        bits_consumed += NBITS;
+      }
+
+      /* How many subnet entries to set : 1->8, 2->4, 3->2 */
+      N = 1 << (NBITS-bits_to_go);
+
+      subnet = get_subnet(ip, bits_consumed) & ~(N - 1);
+      assert(subnet + N <= TABLE_SIZE);
+
+      if (!(node->extended)) {
+        open_node(node);
+      }
+      
+      for (i=subnet, j=0; j<N; i++, j++) {
+        this_node = &(node->extended[i]);
+        if (delete_children) {
+          close_node(this_node);
+        }
+        this_node->state = new_state;
+      }
+    }
+    
+    return ADF_SUCCESS;
+  }
+  
+}
+
+/* ================================================== */
+
+static ADF_Status
+set_subnet_(ADF_AuthTable table,
+           IPAddr *ip_addr,
+           int subnet_bits,
+           State new_state,
+           int delete_children)
+{
+  uint32_t ip6[4];
+
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+      return set_subnet(&table->base4, &ip_addr->addr.in4, 1, subnet_bits, new_state, delete_children);
+    case IPADDR_INET6:
+      split_ip6(ip_addr, ip6);
+      return set_subnet(&table->base6, ip6, 4, subnet_bits, new_state, delete_children);
+    case IPADDR_UNSPEC:
+      /* Apply to both, subnet_bits has to be 0 */
+      if (subnet_bits != 0)
+        return ADF_BADSUBNET;
+      memset(ip6, 0, sizeof (ip6));
+      if (set_subnet(&table->base4, ip6, 1, 0, new_state, delete_children) == ADF_SUCCESS &&
+          set_subnet(&table->base6, ip6, 4, 0, new_state, delete_children) == ADF_SUCCESS)
+        return ADF_SUCCESS;
+      break;
+    default:
+      break;
+  }
+
+  return ADF_BADSUBNET;
+}
+
+ADF_Status
+ADF_Allow(ADF_AuthTable table,
+          IPAddr *ip,
+          int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, ALLOW, 0);
+}
+
+/* ================================================== */
+
+
+ADF_Status
+ADF_AllowAll(ADF_AuthTable table,
+             IPAddr *ip,
+             int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, ALLOW, 1);
+}
+
+/* ================================================== */
+
+ADF_Status
+ADF_Deny(ADF_AuthTable table,
+         IPAddr *ip,
+         int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, DENY, 0);
+}
+
+/* ================================================== */
+
+ADF_Status
+ADF_DenyAll(ADF_AuthTable table,
+            IPAddr *ip,
+            int subnet_bits)
+{
+  return set_subnet_(table, ip, subnet_bits, DENY, 1);
+}
+
+/* ================================================== */
+
+void
+ADF_DestroyTable(ADF_AuthTable table)
+{
+  close_node(&table->base4);
+  close_node(&table->base6);
+  Free(table);
+}
+
+/* ================================================== */
+
+static int
+check_ip_in_node(TableNode *start_node, uint32_t *ip)
+{
+  uint32_t subnet;
+  int bits_consumed = 0;
+  int result = 0;
+  int finished = 0;
+  TableNode *node;
+  State state=DENY;
+
+  node = start_node;
+
+  do {
+    if (node->state != AS_PARENT) {
+      state = node->state;
+    }
+    if (node->extended) {
+      subnet = get_subnet(ip, bits_consumed);
+      node = &(node->extended[subnet]);
+      bits_consumed += NBITS;
+    } else {
+      /* Make decision on this node */
+      finished = 1;
+    }
+  } while (!finished);
+
+  switch (state) {
+    case ALLOW:
+      result = 1;
+      break;
+    case DENY:
+      result = 0;
+      break;
+    case AS_PARENT:
+      assert(0);
+      break;
+  }
+
+  return result;
+}
+
+
+/* ================================================== */
+
+int
+ADF_IsAllowed(ADF_AuthTable table,
+              IPAddr *ip_addr)
+{
+  uint32_t ip6[4];
+
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+      return check_ip_in_node(&table->base4, &ip_addr->addr.in4);
+    case IPADDR_INET6:
+      split_ip6(ip_addr, ip6);
+      return check_ip_in_node(&table->base6, ip6);
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+is_any_allowed(TableNode *node, State parent)
+{
+  State state;
+  int i;
+
+  state = node->state != AS_PARENT ? node->state : parent;
+  assert(state != AS_PARENT);
+
+  if (node->extended) {
+    for (i = 0; i < TABLE_SIZE; i++) {
+      if (is_any_allowed(&node->extended[i], state))
+        return 1;
+    }
+  } else if (state == ALLOW) {
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+ADF_IsAnyAllowed(ADF_AuthTable table, int family)
+{
+  switch (family) {
+    case IPADDR_INET4:
+      return is_any_allowed(&table->base4, AS_PARENT);
+    case IPADDR_INET6:
+      return is_any_allowed(&table->base6, AS_PARENT);
+    default:
+      return 0;
+  }
+}
diff --git a/addrfilt.h b/addrfilt.h
new file mode 100644
index 0000000..b8c131f
--- /dev/null
+++ b/addrfilt.h
@@ -0,0 +1,80 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module for providing an authorisation filter on IP addresses
+  */
+
+#ifndef GOT_ADDRFILT_H
+#define GOT_ADDRFILT_H
+
+#include "addressing.h"
+
+typedef struct ADF_AuthTableInst *ADF_AuthTable;
+
+typedef enum {
+  ADF_SUCCESS,
+  ADF_BADSUBNET
+} ADF_Status;
+  
+
+/* Create a new table.  The default rule is deny for everything */
+extern ADF_AuthTable ADF_CreateTable(void);
+
+/* Allow anything in the supplied subnet, EXCEPT for any more specific
+   subnets that are already defined */
+extern ADF_Status ADF_Allow(ADF_AuthTable table,
+                            IPAddr *ip,
+                            int subnet_bits);
+
+/* Allow anything in the supplied subnet, overwriting existing
+   definitions for any more specific subnets */
+extern ADF_Status ADF_AllowAll(ADF_AuthTable table,
+                               IPAddr *ip,
+                               int subnet_bits);
+
+/* Deny anything in the supplied subnet, EXCEPT for any more specific
+   subnets that are already defined */
+extern ADF_Status ADF_Deny(ADF_AuthTable table,
+                           IPAddr *ip,
+                           int subnet_bits);
+
+/* Deny anything in the supplied subnet, overwriting existing
+   definitions for any more specific subnets */
+extern ADF_Status ADF_DenyAll(ADF_AuthTable table,
+                              IPAddr *ip,
+                              int subnet_bits);
+
+/* Clear up the table */
+extern void ADF_DestroyTable(ADF_AuthTable table);
+
+/* Check whether a given IP address is allowed by the rules in 
+   the table */
+extern int ADF_IsAllowed(ADF_AuthTable table,
+                         IPAddr *ip);
+
+/* Check if at least one address from a given family is allowed by
+   the rules in the table */
+extern int ADF_IsAnyAllowed(ADF_AuthTable table,
+                            int family);
+
+#endif /* GOT_ADDRFILT_H */
diff --git a/array.c b/array.c
new file mode 100644
index 0000000..b31ba56
--- /dev/null
+++ b/array.c
@@ -0,0 +1,145 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions implementing an array with automatic memory allocation.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "memory.h"
+
+struct ARR_Instance_Record {
+  void *data;
+  unsigned int elem_size;
+  unsigned int used;
+  unsigned int allocated;
+};
+
+ARR_Instance
+ARR_CreateInstance(unsigned int elem_size)
+{
+  ARR_Instance array;
+
+  assert(elem_size > 0);
+
+  array = MallocNew(struct ARR_Instance_Record);
+
+  array->data = NULL;
+  array->elem_size = elem_size;
+  array->used = 0;
+  array->allocated = 0;
+
+  return array;
+}
+
+void
+ARR_DestroyInstance(ARR_Instance array)
+{
+  Free(array->data);
+  Free(array);
+}
+
+static void
+realloc_array(ARR_Instance array, unsigned int min_size)
+{
+  assert(min_size <= 2 * min_size);
+  if (array->allocated >= min_size && array->allocated <= 2 * min_size)
+    return;
+
+  if (array->allocated < min_size) {
+    while (array->allocated < min_size)
+      array->allocated = array->allocated ? 2 * array->allocated : 1;
+  } else {
+    array->allocated = min_size;
+  }
+
+  array->data = Realloc2(array->data, array->allocated, array->elem_size);
+}
+
+void *
+ARR_GetNewElement(ARR_Instance array)
+{
+  array->used++;
+  realloc_array(array, array->used);
+  return ARR_GetElement(array, array->used - 1);
+}
+
+void *
+ARR_GetElement(ARR_Instance array, unsigned int index)
+{
+  assert(index < array->used);
+  return (void *)((char *)array->data + (size_t)index * array->elem_size);
+}
+
+void *
+ARR_GetElements(ARR_Instance array)
+{
+  /* Return a non-NULL pointer when the array has zero size */
+  if (!array->data) {
+    assert(!array->used);
+    return array;
+  }
+
+  return array->data;
+}
+
+void
+ARR_AppendElement(ARR_Instance array, void *element)
+{
+  void *e;
+
+  e = ARR_GetNewElement(array);
+  memcpy(e, element, array->elem_size);
+}
+
+void
+ARR_RemoveElement(ARR_Instance array, unsigned int index)
+{
+  void *e, *l;
+
+  e = ARR_GetElement(array, index);
+  l = ARR_GetElement(array, array->used - 1);
+
+  if (e < l)
+    memmove(e, (char *)e + array->elem_size, (char *)l - (char *)e);
+  array->used--;
+
+  realloc_array(array, array->used);
+}
+
+void
+ARR_SetSize(ARR_Instance array, unsigned int size)
+{
+  realloc_array(array, size);
+  array->used = size;
+}
+
+unsigned int
+ARR_GetSize(ARR_Instance array)
+{
+  return array->used;
+}
diff --git a/array.h b/array.h
new file mode 100644
index 0000000..f4fbddb
--- /dev/null
+++ b/array.h
@@ -0,0 +1,59 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for array functions.
+  */
+
+#ifndef GOT_ARRAY_H
+#define GOT_ARRAY_H
+
+typedef struct ARR_Instance_Record *ARR_Instance;
+
+/* Create a new array with given element size */
+extern ARR_Instance ARR_CreateInstance(unsigned int elem_size);
+
+/* Destroy the array */
+extern void ARR_DestroyInstance(ARR_Instance array);
+
+/* Return pointer to a new element added to the end of the array */
+extern void *ARR_GetNewElement(ARR_Instance array);
+
+/* Return element with given index */
+extern void *ARR_GetElement(ARR_Instance array, unsigned int index);
+
+/* Return pointer to the internal array of elements */
+extern void *ARR_GetElements(ARR_Instance array);
+
+/* Add a new element to the end of the array */
+extern void ARR_AppendElement(ARR_Instance array, void *element);
+
+/* Remove element with given index */
+extern void ARR_RemoveElement(ARR_Instance array, unsigned int index);
+
+/* Set the size of the array */
+extern void ARR_SetSize(ARR_Instance array, unsigned int size);
+
+/* Return current size of the array */
+extern unsigned int ARR_GetSize(ARR_Instance array);
+
+#endif
diff --git a/candm.h b/candm.h
new file mode 100644
index 0000000..b5b1b7f
--- /dev/null
+++ b/candm.h
@@ -0,0 +1,849 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Definitions for the network protocol used for command and monitoring
+  of the timeserver.
+
+  */
+
+#ifndef GOT_CANDM_H
+#define GOT_CANDM_H
+
+#include "sysincl.h"
+#include "addressing.h"
+
+/* This is the default port to use for CANDM, if no alternative is
+   defined */
+#define DEFAULT_CANDM_PORT 323
+
+/* Request codes */
+#define REQ_NULL 0
+#define REQ_ONLINE 1
+#define REQ_OFFLINE 2
+#define REQ_BURST 3
+#define REQ_MODIFY_MINPOLL 4
+#define REQ_MODIFY_MAXPOLL 5
+#define REQ_DUMP 6
+#define REQ_MODIFY_MAXDELAY 7
+#define REQ_MODIFY_MAXDELAYRATIO 8
+#define REQ_MODIFY_MAXUPDATESKEW 9
+#define REQ_LOGON 10
+#define REQ_SETTIME 11
+#define REQ_LOCAL 12
+#define REQ_MANUAL 13
+#define REQ_N_SOURCES 14
+#define REQ_SOURCE_DATA 15
+#define REQ_REKEY 16
+#define REQ_ALLOW 17
+#define REQ_ALLOWALL 18
+#define REQ_DENY 19
+#define REQ_DENYALL 20
+#define REQ_CMDALLOW 21
+#define REQ_CMDALLOWALL 22
+#define REQ_CMDDENY 23
+#define REQ_CMDDENYALL 24
+#define REQ_ACCHECK 25
+#define REQ_CMDACCHECK 26
+#define REQ_ADD_SERVER 27
+#define REQ_ADD_PEER 28
+#define REQ_DEL_SOURCE 29
+#define REQ_WRITERTC 30
+#define REQ_DFREQ 31
+#define REQ_DOFFSET 32
+#define REQ_TRACKING 33
+#define REQ_SOURCESTATS 34
+#define REQ_RTCREPORT 35
+#define REQ_TRIMRTC 36
+#define REQ_CYCLELOGS 37
+#define REQ_SUBNETS_ACCESSED 38
+#define REQ_CLIENT_ACCESSES 39
+#define REQ_CLIENT_ACCESSES_BY_INDEX 40
+#define REQ_MANUAL_LIST 41
+#define REQ_MANUAL_DELETE 42
+#define REQ_MAKESTEP 43
+#define REQ_ACTIVITY 44
+#define REQ_MODIFY_MINSTRATUM 45
+#define REQ_MODIFY_POLLTARGET 46
+#define REQ_MODIFY_MAXDELAYDEVRATIO 47
+#define REQ_RESELECT 48
+#define REQ_RESELECTDISTANCE 49
+#define REQ_MODIFY_MAKESTEP 50
+#define REQ_SMOOTHING 51
+#define REQ_SMOOTHTIME 52
+#define REQ_REFRESH 53
+#define REQ_SERVER_STATS 54
+#define REQ_CLIENT_ACCESSES_BY_INDEX2 55
+#define REQ_LOCAL2 56
+#define REQ_NTP_DATA 57
+#define REQ_ADD_SERVER2 58
+#define REQ_ADD_PEER2 59
+#define REQ_ADD_SERVER3 60
+#define REQ_ADD_PEER3 61
+#define REQ_SHUTDOWN 62
+#define REQ_ONOFFLINE 63
+#define REQ_ADD_SOURCE 64
+#define REQ_NTP_SOURCE_NAME 65
+#define REQ_RESET_SOURCES 66
+#define REQ_AUTH_DATA 67
+#define REQ_CLIENT_ACCESSES_BY_INDEX3 68
+#define REQ_SELECT_DATA 69
+#define REQ_RELOAD_SOURCES 70
+#define REQ_DOFFSET2 71
+#define REQ_MODIFY_SELECTOPTS 72
+#define N_REQUEST_TYPES 73
+
+/* Structure used to exchange timespecs independent of time_t size */
+typedef struct {
+  uint32_t tv_sec_high;
+  uint32_t tv_sec_low;
+  uint32_t tv_nsec;
+} Timespec;
+
+/* This is used in tv_sec_high for 32-bit timestamps */
+#define TV_NOHIGHSEC 0x7fffffff
+
+/* Structure for 64-bit integers (not requiring 64-bit alignment) */
+typedef struct {
+  uint32_t high;
+  uint32_t low;
+} Integer64;
+
+/* 32-bit floating-point format consisting of 7-bit signed exponent
+   and 25-bit signed coefficient without hidden bit.
+   The result is calculated as: 2^(exp - 25) * coef */
+typedef struct {
+  int32_t f;
+} Float;
+
+/* The EOR (end of record) fields are used by the offsetof operator in
+   pktlength.c, to get the number of bytes that ought to be
+   transmitted for each packet type. */
+
+typedef struct {
+  int32_t EOR;
+} REQ_Null;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t EOR;
+} REQ_Online;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t EOR;
+} REQ_Offline;
+
+typedef struct {
+  IPAddr mask;
+  IPAddr address;
+  int32_t n_good_samples;
+  int32_t n_total_samples;
+  int32_t EOR;
+} REQ_Burst;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_minpoll;
+  int32_t EOR;
+} REQ_Modify_Minpoll;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_maxpoll;
+  int32_t EOR;
+} REQ_Modify_Maxpoll;
+
+typedef struct {
+  int32_t pad;
+  int32_t EOR;
+} REQ_Dump;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay;
+  int32_t EOR;
+} REQ_Modify_Maxdelay;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay_ratio;
+  int32_t EOR;
+} REQ_Modify_Maxdelayratio;
+
+typedef struct {
+  IPAddr address;
+  Float new_max_delay_dev_ratio;
+  int32_t EOR;
+} REQ_Modify_Maxdelaydevratio;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_min_stratum;
+  int32_t EOR;
+} REQ_Modify_Minstratum;
+
+typedef struct {
+  IPAddr address;
+  int32_t new_poll_target;
+  int32_t EOR;
+} REQ_Modify_Polltarget;
+
+typedef struct {
+  Float new_max_update_skew;
+  int32_t EOR;
+} REQ_Modify_Maxupdateskew;
+
+typedef struct {
+  int32_t limit;
+  Float threshold;
+  int32_t EOR;
+} REQ_Modify_Makestep;
+
+typedef struct {
+  Timespec ts;
+  int32_t EOR;
+} REQ_Logon;
+
+typedef struct {
+  Timespec ts;
+  int32_t EOR;
+} REQ_Settime;
+
+typedef struct {
+  int32_t on_off;
+  int32_t stratum;
+  Float distance;
+  int32_t orphan;
+  int32_t EOR;
+} REQ_Local;
+
+typedef struct {
+  int32_t option;
+  int32_t EOR;
+} REQ_Manual;
+
+typedef struct {
+  int32_t index;
+  int32_t EOR;
+} REQ_Source_Data;
+
+typedef struct {
+  IPAddr ip;
+  int32_t subnet_bits;
+  int32_t EOR;
+} REQ_Allow_Deny;
+
+typedef struct {
+  IPAddr ip;
+  int32_t EOR;
+} REQ_Ac_Check;
+
+/* Source types in NTP source requests */
+#define REQ_ADDSRC_SERVER 1
+#define REQ_ADDSRC_PEER 2
+#define REQ_ADDSRC_POOL 3
+
+/* Flags used in NTP source requests */
+#define REQ_ADDSRC_ONLINE 0x1
+#define REQ_ADDSRC_AUTOOFFLINE 0x2
+#define REQ_ADDSRC_IBURST 0x4
+#define REQ_ADDSRC_PREFER 0x8
+#define REQ_ADDSRC_NOSELECT 0x10
+#define REQ_ADDSRC_TRUST 0x20
+#define REQ_ADDSRC_REQUIRE 0x40
+#define REQ_ADDSRC_INTERLEAVED 0x80
+#define REQ_ADDSRC_BURST 0x100
+#define REQ_ADDSRC_NTS 0x200
+#define REQ_ADDSRC_COPY 0x400
+#define REQ_ADDSRC_EF_EXP1 0x800
+
+typedef struct {
+  uint32_t type;
+  uint8_t name[256];
+  uint32_t port;
+  int32_t minpoll;
+  int32_t maxpoll;
+  int32_t presend_minpoll;
+  uint32_t min_stratum;
+  uint32_t poll_target;
+  uint32_t version;
+  uint32_t max_sources;
+  int32_t min_samples;
+  int32_t max_samples;
+  uint32_t authkey;
+  uint32_t nts_port;
+  Float max_delay;
+  Float max_delay_ratio;
+  Float max_delay_dev_ratio;
+  Float min_delay;
+  Float asymmetry;
+  Float offset;
+  uint32_t flags;
+  int32_t filter_length;
+  uint32_t cert_set;
+  Float max_delay_quant;
+  uint32_t reserved[1];
+  int32_t EOR;
+} REQ_NTP_Source;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_Del_Source;
+
+typedef struct {
+  Float dfreq;
+  int32_t EOR;
+} REQ_Dfreq;
+
+typedef struct {
+  Float doffset;
+  int32_t EOR;
+} REQ_Doffset;
+
+typedef struct {
+  uint32_t index;
+  int32_t EOR;
+} REQ_Sourcestats;
+
+/* This is based on the response size rather than the
+   request size */
+#define MAX_CLIENT_ACCESSES 8
+
+typedef struct {
+  uint32_t first_index;
+  uint32_t n_clients;
+  uint32_t min_hits;
+  uint32_t reset;
+  int32_t EOR;
+} REQ_ClientAccessesByIndex;
+
+typedef struct {
+  int32_t index;
+  int32_t EOR;
+} REQ_ManualDelete;
+
+typedef struct {
+  Float distance;
+  int32_t EOR;
+} REQ_ReselectDistance;
+
+#define REQ_SMOOTHTIME_RESET 0
+#define REQ_SMOOTHTIME_ACTIVATE 1
+
+typedef struct {
+  int32_t option;
+  int32_t EOR;
+} REQ_SmoothTime;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_NTPData;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_NTPSourceName;
+
+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_AuthData;
+
+typedef struct {
+  uint32_t index;
+  int32_t EOR;
+} REQ_SelectData;
+
+/* Mask and options reuse the REQ_ADDSRC flags */
+typedef struct {
+  IPAddr address;
+  uint32_t ref_id;
+  uint32_t mask;
+  uint32_t options;
+  int32_t EOR;
+} REQ_Modify_SelectOpts;
+
+/* ================================================== */
+
+#define PKT_TYPE_CMD_REQUEST 1
+#define PKT_TYPE_CMD_REPLY 2
+
+/* This version number needs to be incremented whenever the packet
+   size and/or the format of any of the existing messages is changed.
+   Other changes, e.g. new command types, should be handled cleanly by
+   client.c and cmdmon.c anyway, so the version can stay the same.
+   
+   Version 1 : original version with fixed size packets
+
+   Version 2 : both command and reply packet sizes made capable of
+   being variable length.
+
+   Version 3 : NTP_Source message lengthened (auto_offline)
+
+   Version 4 : IPv6 addressing added, 64-bit time values, sourcestats 
+   and tracking reports extended, added flags to NTP source request,
+   trimmed source report, replaced fixed-point format with floating-point
+   and used also instead of integer microseconds, new commands: modify stratum,
+   modify polltarget, modify maxdelaydevratio, reselect, reselectdistance
+
+   Version 5 : auth data moved to the end of the packet to allow hashes with
+   different sizes, extended sources, tracking and activity reports, dropped
+   subnets accessed and client accesses
+
+   Version 6 : added padding to requests to prevent amplification attack,
+   changed maximum number of samples in manual list to 16, new commands: modify
+   makestep, smoothing, smoothtime
+
+   Support for authentication was removed later in version 6 of the protocol
+   and commands that required authentication are allowed only locally over Unix
+   domain socket.
+
+   Version 6 (no authentication) : changed format of client accesses by index
+   (two times), delta offset, and manual timestamp, added new fields and
+   flags to NTP source request and report, made length of manual list constant,
+   added new commands: authdata, ntpdata, onoffline, refresh, reset,
+   selectdata, serverstats, shutdown, sourcename
+ */
+
+#define PROTO_VERSION_NUMBER 6
+
+/* The oldest protocol versions that are compatible enough with the current
+   version to report a version mismatch for the server and the client */
+#define PROTO_VERSION_MISMATCH_COMPAT_SERVER 5
+#define PROTO_VERSION_MISMATCH_COMPAT_CLIENT 4
+
+/* The first protocol version using padding in requests */
+#define PROTO_VERSION_PADDING 6
+
+/* The maximum length of padding in request packet, currently
+   defined by CLIENT_ACCESSES_BY_INDEX3 */
+#define MAX_PADDING_LENGTH 484
+
+/* ================================================== */
+
+typedef struct {
+  uint8_t version; /* Protocol version */
+  uint8_t pkt_type; /* What sort of packet this is */
+  uint8_t res1;
+  uint8_t res2;
+  uint16_t command; /* Which command is being issued */
+  uint16_t attempt; /* How many resends the client has done
+                             (count up from zero for same sequence
+                             number) */
+  uint32_t sequence; /* Client's sequence number */
+  uint32_t pad1;
+  uint32_t pad2;
+
+  union {
+    REQ_Null null;
+    REQ_Online online;
+    REQ_Offline offline;
+    REQ_Burst burst;
+    REQ_Modify_Minpoll modify_minpoll;
+    REQ_Modify_Maxpoll modify_maxpoll;
+    REQ_Dump dump;
+    REQ_Modify_Maxdelay modify_maxdelay;
+    REQ_Modify_Maxdelayratio modify_maxdelayratio;
+    REQ_Modify_Maxdelaydevratio modify_maxdelaydevratio;
+    REQ_Modify_Minstratum modify_minstratum;
+    REQ_Modify_Polltarget modify_polltarget;
+    REQ_Modify_Maxupdateskew modify_maxupdateskew;
+    REQ_Modify_Makestep modify_makestep;
+    REQ_Logon logon;
+    REQ_Settime settime;
+    REQ_Local local;
+    REQ_Manual manual;
+    REQ_Source_Data source_data;
+    REQ_Allow_Deny allow_deny;
+    REQ_Ac_Check ac_check;
+    REQ_NTP_Source ntp_source;
+    REQ_Del_Source del_source;
+    REQ_Dfreq dfreq;
+    REQ_Doffset doffset;
+    REQ_Sourcestats sourcestats;
+    REQ_ClientAccessesByIndex client_accesses_by_index;
+    REQ_ManualDelete manual_delete;
+    REQ_ReselectDistance reselect_distance;
+    REQ_SmoothTime smoothtime;
+    REQ_NTPData ntp_data;
+    REQ_NTPSourceName ntp_source_name;
+    REQ_AuthData auth_data;
+    REQ_SelectData select_data;
+    REQ_Modify_SelectOpts modify_select_opts;
+  } data; /* Command specific parameters */
+
+  /* Padding used to prevent traffic amplification.  It only defines the
+     maximum size of the packet, there is no hole after the data field. */
+  uint8_t padding[MAX_PADDING_LENGTH];
+
+} CMD_Request;
+
+/* ================================================== */
+/* Authority codes for command types */
+
+#define PERMIT_OPEN 0
+#define PERMIT_LOCAL 1
+#define PERMIT_AUTH 2
+
+/* ================================================== */
+
+/* Reply codes */
+#define RPY_NULL 1
+#define RPY_N_SOURCES 2
+#define RPY_SOURCE_DATA 3
+#define RPY_MANUAL_TIMESTAMP 4
+#define RPY_TRACKING 5
+#define RPY_SOURCESTATS 6
+#define RPY_RTC 7
+#define RPY_SUBNETS_ACCESSED 8
+#define RPY_CLIENT_ACCESSES 9
+#define RPY_CLIENT_ACCESSES_BY_INDEX 10
+#define RPY_MANUAL_LIST 11
+#define RPY_ACTIVITY 12
+#define RPY_SMOOTHING 13
+#define RPY_SERVER_STATS 14
+#define RPY_CLIENT_ACCESSES_BY_INDEX2 15
+#define RPY_NTP_DATA 16
+#define RPY_MANUAL_TIMESTAMP2 17
+#define RPY_MANUAL_LIST2 18
+#define RPY_NTP_SOURCE_NAME 19
+#define RPY_AUTH_DATA 20
+#define RPY_CLIENT_ACCESSES_BY_INDEX3 21
+#define RPY_SERVER_STATS2 22
+#define RPY_SELECT_DATA 23
+#define RPY_SERVER_STATS3 24
+#define RPY_SERVER_STATS4 25
+#define N_REPLY_TYPES 26
+
+/* Status codes */
+#define STT_SUCCESS 0
+#define STT_FAILED 1
+#define STT_UNAUTH 2
+#define STT_INVALID 3
+#define STT_NOSUCHSOURCE 4
+#define STT_INVALIDTS 5
+#define STT_NOTENABLED 6
+#define STT_BADSUBNET 7
+#define STT_ACCESSALLOWED 8
+#define STT_ACCESSDENIED 9
+#define STT_NOHOSTACCESS 10 /* Deprecated */
+#define STT_SOURCEALREADYKNOWN 11
+#define STT_TOOMANYSOURCES 12
+#define STT_NORTC 13
+#define STT_BADRTCFILE 14
+#define STT_INACTIVE 15
+#define STT_BADSAMPLE 16
+#define STT_INVALIDAF 17
+#define STT_BADPKTVERSION 18
+#define STT_BADPKTLENGTH 19
+#define STT_INVALIDNAME 21
+
+typedef struct {
+  int32_t EOR;
+} RPY_Null;
+
+typedef struct {
+  uint32_t n_sources;
+  int32_t EOR;
+} RPY_N_Sources;
+
+#define RPY_SD_MD_CLIENT 0
+#define RPY_SD_MD_PEER   1
+#define RPY_SD_MD_REF    2
+
+#define RPY_SD_ST_SELECTED 0
+#define RPY_SD_ST_NONSELECTABLE 1
+#define RPY_SD_ST_FALSETICKER 2
+#define RPY_SD_ST_JITTERY 3
+#define RPY_SD_ST_UNSELECTED 4
+#define RPY_SD_ST_SELECTABLE 5
+
+typedef struct {
+  IPAddr ip_addr;
+  int16_t poll;
+  uint16_t stratum;
+  uint16_t state;
+  uint16_t mode;
+  uint16_t flags;
+  uint16_t reachability;
+  uint32_t  since_sample;
+  Float orig_latest_meas;
+  Float latest_meas;
+  Float latest_meas_err;
+  int32_t EOR;
+} RPY_Source_Data;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint16_t stratum;
+  uint16_t leap_status;
+  Timespec ref_time;
+  Float current_correction;
+  Float last_offset;
+  Float rms_offset;
+  Float freq_ppm;
+  Float resid_freq_ppm;
+  Float skew_ppm;
+  Float root_delay;
+  Float root_dispersion;
+  Float last_update_interval;
+  int32_t EOR;
+} RPY_Tracking;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint32_t n_samples;
+  uint32_t n_runs;
+  uint32_t span_seconds;
+  Float sd;
+  Float resid_freq_ppm;
+  Float skew_ppm;
+  Float est_offset;
+  Float est_offset_err;
+  int32_t EOR;
+} RPY_Sourcestats;
+
+typedef struct {
+  Timespec ref_time;
+  uint16_t n_samples;
+  uint16_t n_runs;
+  uint32_t span_seconds;
+  Float rtc_seconds_fast;
+  Float rtc_gain_rate_ppm;
+  int32_t EOR;
+} RPY_Rtc;
+
+typedef struct {
+  Float offset;
+  Float dfreq_ppm;
+  Float new_afreq_ppm;
+  int32_t EOR;
+} RPY_ManualTimestamp;
+
+typedef struct {
+  IPAddr ip;
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint32_t ntp_drops;
+  uint32_t nke_drops;
+  uint32_t cmd_drops;
+  int8_t ntp_interval;
+  int8_t nke_interval;
+  int8_t cmd_interval;
+  int8_t ntp_timeout_interval;
+  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
+  uint32_t last_cmd_hit_ago;
+} RPY_ClientAccesses_Client;
+
+typedef struct {
+  uint32_t n_indices;      /* how many indices there are in the server's table */
+  uint32_t next_index;     /* the index 1 beyond those processed on this call */
+  uint32_t n_clients;      /* the number of valid entries in the following array */
+  RPY_ClientAccesses_Client clients[MAX_CLIENT_ACCESSES];
+  int32_t EOR;
+} RPY_ClientAccessesByIndex;
+
+typedef struct {
+  Integer64 ntp_hits;
+  Integer64 nke_hits;
+  Integer64 cmd_hits;
+  Integer64 ntp_drops;
+  Integer64 nke_drops;
+  Integer64 cmd_drops;
+  Integer64 log_drops;
+  Integer64 ntp_auth_hits;
+  Integer64 ntp_interleaved_hits;
+  Integer64 ntp_timestamps;
+  Integer64 ntp_span_seconds;
+  Integer64 ntp_daemon_rx_timestamps;
+  Integer64 ntp_daemon_tx_timestamps;
+  Integer64 ntp_kernel_rx_timestamps;
+  Integer64 ntp_kernel_tx_timestamps;
+  Integer64 ntp_hw_rx_timestamps;
+  Integer64 ntp_hw_tx_timestamps;
+  Integer64 reserved[4];
+  int32_t EOR;
+} RPY_ServerStats;
+
+#define MAX_MANUAL_LIST_SAMPLES 16
+
+typedef struct {
+  Timespec when;
+  Float slewed_offset;
+  Float orig_offset;
+  Float residual;
+} RPY_ManualListSample;
+
+typedef struct {
+  uint32_t n_samples;
+  RPY_ManualListSample samples[MAX_MANUAL_LIST_SAMPLES];
+  int32_t EOR;
+} RPY_ManualList;
+
+typedef struct {
+  int32_t online;
+  int32_t offline;
+  int32_t burst_online;
+  int32_t burst_offline;
+  int32_t unresolved;
+  int32_t EOR;
+} RPY_Activity;
+
+#define RPY_SMT_FLAG_ACTIVE 0x1
+#define RPY_SMT_FLAG_LEAPONLY 0x2
+
+typedef struct {
+  uint32_t flags;
+  Float offset;
+  Float freq_ppm;
+  Float wander_ppm;
+  Float last_update_ago;
+  Float remaining_time;
+  int32_t EOR;
+} RPY_Smoothing;
+
+#define RPY_NTP_FLAGS_TESTS 0x3ff
+#define RPY_NTP_FLAG_INTERLEAVED 0x4000
+#define RPY_NTP_FLAG_AUTHENTICATED 0x8000
+
+typedef struct {
+  IPAddr remote_addr;
+  IPAddr local_addr;
+  uint16_t remote_port;
+  uint8_t leap;
+  uint8_t version;
+  uint8_t mode;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  Float root_delay;
+  Float root_dispersion;
+  uint32_t ref_id;
+  Timespec ref_time;
+  Float offset;
+  Float peer_delay;
+  Float peer_dispersion;
+  Float response_time;
+  Float jitter_asymmetry;
+  uint16_t flags;
+  uint8_t tx_tss_char;
+  uint8_t rx_tss_char;
+  uint32_t total_tx_count;
+  uint32_t total_rx_count;
+  uint32_t total_valid_count;
+  uint32_t total_good_count;
+  uint32_t reserved[3];
+  int32_t EOR;
+} RPY_NTPData;
+
+typedef struct {
+  uint8_t name[256];
+  int32_t EOR;
+} RPY_NTPSourceName;
+
+#define RPY_AD_MD_NONE 0
+#define RPY_AD_MD_SYMMETRIC 1
+#define RPY_AD_MD_NTS 2
+
+typedef struct {
+  uint16_t mode;
+  uint16_t key_type;
+  uint32_t key_id;
+  uint16_t key_length;
+  uint16_t ke_attempts;
+  uint32_t last_ke_ago;
+  uint16_t cookies;
+  uint16_t cookie_length;
+  uint16_t nak;
+  uint16_t pad;
+  int32_t EOR;
+} RPY_AuthData;
+
+#define RPY_SD_OPTION_NOSELECT 0x1
+#define RPY_SD_OPTION_PREFER 0x2
+#define RPY_SD_OPTION_TRUST 0x4
+#define RPY_SD_OPTION_REQUIRE 0x8
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint8_t state_char;
+  uint8_t authentication;
+  uint8_t leap;
+  uint8_t pad;
+  uint16_t conf_options;
+  uint16_t eff_options;
+  uint32_t last_sample_ago;
+  Float score;
+  Float lo_limit;
+  Float hi_limit;
+  int32_t EOR;
+} RPY_SelectData;
+
+typedef struct {
+  uint8_t version;
+  uint8_t pkt_type;
+  uint8_t res1;
+  uint8_t res2;
+  uint16_t command; /* Which command is being replied to */
+  uint16_t reply; /* Which format of reply this is */
+  uint16_t status; /* Status of command processing */
+  uint16_t pad1; /* Padding for compatibility and 4 byte alignment */
+  uint16_t pad2;
+  uint16_t pad3;
+  uint32_t sequence; /* Echo of client's sequence number */
+  uint32_t pad4;
+  uint32_t pad5;
+
+  union {
+    RPY_Null null;
+    RPY_N_Sources n_sources;
+    RPY_Source_Data source_data;
+    RPY_ManualTimestamp manual_timestamp;
+    RPY_Tracking tracking;
+    RPY_Sourcestats sourcestats;
+    RPY_Rtc rtc;
+    RPY_ClientAccessesByIndex client_accesses_by_index;
+    RPY_ServerStats server_stats;
+    RPY_ManualList manual_list;
+    RPY_Activity activity;
+    RPY_Smoothing smoothing;
+    RPY_NTPData ntp_data;
+    RPY_NTPSourceName ntp_source_name;
+    RPY_AuthData auth_data;
+    RPY_SelectData select_data;
+  } data; /* Reply specific parameters */
+
+} CMD_Reply;
+
+/* ================================================== */
+
+#endif /* GOT_CANDM_H */
diff --git a/client.c b/client.c
new file mode 100644
index 0000000..5c056bc
--- /dev/null
+++ b/client.c
@@ -0,0 +1,3535 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Lonnie Abelbeck  2016, 2018
+ * Copyright (C) Miroslav Lichvar  2009-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Command line client for configuring the daemon and obtaining status
+  from it whilst running.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "candm.h"
+#include "cmac.h"
+#include "logging.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "getdate.h"
+#include "cmdparse.h"
+#include "pktlength.h"
+#include "socket.h"
+#include "util.h"
+
+#ifdef FEAT_READLINE
+#include <editline/readline.h>
+#endif
+
+/* ================================================== */
+
+struct Address {
+  SCK_AddressType type;
+  union {
+    IPSockAddr ip;
+    char *path;
+  } addr;
+};
+
+static ARR_Instance server_addresses;
+
+static int sock_fd = -1;
+
+static volatile int quit = 0;
+
+static int on_terminal = 0;
+
+static int no_dns = 0;
+
+static int source_names = 0;
+
+static int csv_mode = 0;
+
+static int end_dot = 0;
+
+/* ================================================== */
+/* Log a message. This is a minimalistic replacement of the logging.c
+   implementation to avoid linking with it and other modules. */
+
+LOG_Severity log_min_severity = LOGS_INFO;
+
+void LOG_Message(LOG_Severity severity,
+#if DEBUG > 0
+                 int line_number, const char *filename, const char *function_name,
+#endif
+                 const char *format, ...)
+{
+  va_list ap;
+
+  if (severity < log_min_severity)
+    return;
+
+  va_start(ap, format);
+  vfprintf(stderr, format, ap);
+  putc('\n', stderr);
+  va_end(ap);
+}
+
+/* ================================================== */
+/* Read a single line of commands from standard input */
+
+#ifdef FEAT_READLINE
+static char **command_name_completion(const char *text, int start, int end);
+#endif
+
+static char *
+read_line(void)
+{
+  static char line[2048];
+  static const char *prompt = "chronyc> ";
+
+  if (on_terminal) {
+#ifdef FEAT_READLINE
+    char *cmd;
+
+    rl_attempted_completion_function = command_name_completion;
+    rl_basic_word_break_characters = " \t\n\r";
+
+    /* save line only if not empty */
+    cmd = readline(prompt);
+    if( cmd == NULL ) return( NULL );
+    
+    /* user pressed return */
+    if( *cmd != '\0' ) {
+      strncpy(line, cmd, sizeof(line) - 1);
+      line[sizeof(line) - 1] = '\0';
+      add_history(cmd);
+      /* free the buffer allocated by readline */
+      Free(cmd);
+    } else {
+      /* simulate the user has entered an empty line */
+      *line = '\0';
+    }
+    return( line );
+#else
+    printf("%s", prompt);
+    fflush(stdout);
+#endif
+  }
+  if (fgets(line, sizeof(line), stdin)) {
+    return line;
+  } else {
+    return NULL;
+  }
+  
+}
+
+/* ================================================== */
+
+static ARR_Instance
+get_addresses(const char *hostnames, int port)
+{
+  struct Address *addr;
+  ARR_Instance addrs;
+  char *hostname, *s1, *s2;
+  IPAddr ip_addrs[DNS_MAX_ADDRESSES];
+  int i;
+
+  addrs = ARR_CreateInstance(sizeof (*addr));
+  s1 = Strdup(hostnames);
+
+  /* Parse the comma-separated list of hostnames */
+  for (hostname = s1; hostname && *hostname; hostname = s2) {
+    s2 = strchr(hostname, ',');
+    if (s2)
+      *s2++ = '\0';
+
+    /* hostname starting with / is considered a path of Unix domain socket */
+    if (hostname[0] == '/') {
+      addr = ARR_GetNewElement(addrs);
+      addr->type = SCK_ADDR_UNIX;
+      addr->addr.path = Strdup(hostname);
+    } else {
+      if (DNS_Name2IPAddress(hostname, ip_addrs, DNS_MAX_ADDRESSES) != DNS_Success) {
+        DEBUG_LOG("Could not get IP address for %s", hostname);
+        continue;
+      }
+
+      for (i = 0; i < DNS_MAX_ADDRESSES && ip_addrs[i].family != IPADDR_UNSPEC; i++) {
+        addr = ARR_GetNewElement(addrs);
+        addr->type = SCK_ADDR_IP;
+        addr->addr.ip.ip_addr = ip_addrs[i];
+        addr->addr.ip.port = port;
+        DEBUG_LOG("Resolved %s to %s", hostname, UTI_IPToString(&ip_addrs[i]));
+      }
+    }
+  }
+
+  Free(s1);
+  return addrs;
+}
+
+/* ================================================== */
+
+static void
+free_addresses(ARR_Instance addresses)
+{
+  struct Address *addr;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(addresses); i++) {
+    addr = ARR_GetElement(addresses, i);
+
+    if (addr->type == SCK_ADDR_UNIX)
+      Free(addr->addr.path);
+  }
+
+  ARR_DestroyInstance(addresses);
+}
+
+/* ================================================== */
+/* Initialise the socket used to talk to the daemon */
+
+static int
+open_socket(struct Address *addr)
+{
+  char *dir, *local_addr;
+  size_t local_addr_len;
+
+  switch (addr->type) {
+    case SCK_ADDR_IP:
+      sock_fd = SCK_OpenUdpSocket(&addr->addr.ip, NULL, NULL, 0);
+      break;
+    case SCK_ADDR_UNIX:
+      /* Construct path of our socket.  Use the same directory as the server
+         socket and include our process ID to allow multiple chronyc instances
+         running at the same time. */
+
+      dir = UTI_PathToDir(addr->addr.path);
+      local_addr_len = strlen(dir) + 50;
+      local_addr = Malloc(local_addr_len);
+
+      snprintf(local_addr, local_addr_len, "%s/chronyc.%d.sock", dir, (int)getpid());
+
+      sock_fd = SCK_OpenUnixDatagramSocket(addr->addr.path, local_addr,
+                                           SCK_FLAG_ALL_PERMISSIONS);
+      Free(dir);
+      Free(local_addr);
+
+      break;
+    default:
+      assert(0);
+  }
+
+  if (sock_fd < 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+close_io(void)
+{
+  if (sock_fd < 0)
+    return;
+
+  SCK_RemoveSocket(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  sock_fd = -1;
+}
+
+/* ================================================== */
+
+static int
+open_io(void)
+{
+  static unsigned int address_index = 0;
+  struct Address *addr;
+
+  /* If a socket is already opened, close it and try the next address */
+  if (sock_fd >= 0) {
+    close_io();
+    address_index++;
+  }
+
+  /* Find an address for which a socket can be opened and connected */
+  for (; address_index < ARR_GetSize(server_addresses); address_index++) {
+    addr = ARR_GetElement(server_addresses, address_index);
+
+    if (open_socket(addr))
+      return 1;
+
+    close_io();
+  }
+
+  /* Start from the first address if called again */
+  address_index = 0;
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+bits_to_mask(int bits, int family, IPAddr *mask)
+{
+  int i;
+
+  mask->family = family;
+  switch (family) {
+    case IPADDR_INET4:
+      if (bits > 32 || bits < 0)
+        bits = 32;
+      if (bits > 0) {
+        mask->addr.in4 = -1;
+        mask->addr.in4 <<= 32 - bits;
+      } else {
+        mask->addr.in4 = 0;
+      }
+      break;
+    case IPADDR_INET6:
+      if (bits > 128 || bits < 0)
+        bits = 128;
+      for (i = 0; i < bits / 8; i++)
+        mask->addr.in6[i] = 0xff;
+      if (i < 16)
+        mask->addr.in6[i++] = (0xff << (8 - bits % 8)) & 0xff;
+      for (; i < 16; i++)
+        mask->addr.in6[i] = 0x0;
+      break;
+    case IPADDR_ID:
+      mask->family = IPADDR_UNSPEC;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static int
+parse_source_address(char *word, IPAddr *address)
+{
+  if (UTI_StringToIdIP(word, address))
+    return 1;
+
+  if (DNS_Name2IPAddress(word, address, 1) == DNS_Success)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+read_mask_address(char *line, IPAddr *mask, IPAddr *address)
+{
+  unsigned int bits;
+  char *p, *q;
+
+  p = line;
+  if (!*p) {
+    mask->family = address->family = IPADDR_UNSPEC;
+    return 1;
+  } else {
+    q = strchr(p, '/');
+    if (q) {
+      *q++ = 0;
+      if (UTI_StringToIP(p, mask)) {
+        p = q;
+        if (UTI_StringToIP(p, address)) {
+          if (address->family == mask->family)
+            return 1;
+        } else if (sscanf(p, "%u", &bits) == 1) {
+          *address = *mask;
+          bits_to_mask(bits, address->family, mask);
+          return 1;
+        }
+      }
+    } else {
+      if (parse_source_address(p, address)) {
+        bits_to_mask(-1, address->family, mask);
+        return 1;
+      } else {
+        LOG(LOGS_ERR, "Could not get address for hostname");
+        return 0;
+      }
+    }
+  }
+
+  LOG(LOGS_ERR, "Invalid syntax for mask/address");
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_offline(CMD_Request *msg, char *line)
+{
+  IPAddr mask, address;
+  int ok;
+
+  if (read_mask_address(line, &mask, &address)) {
+    UTI_IPHostToNetwork(&mask, &msg->data.offline.mask);
+    UTI_IPHostToNetwork(&address, &msg->data.offline.address);
+    msg->command = htons(REQ_OFFLINE);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+
+static int
+process_cmd_online(CMD_Request *msg, char *line)
+{
+  IPAddr mask, address;
+  int ok;
+
+  if (read_mask_address(line, &mask, &address)) {
+    UTI_IPHostToNetwork(&mask, &msg->data.online.mask);
+    UTI_IPHostToNetwork(&address, &msg->data.online.address);
+    msg->command = htons(REQ_ONLINE);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static void
+process_cmd_onoffline(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_ONOFFLINE);
+}
+
+/* ================================================== */
+
+static int
+read_address_integer(char *line, IPAddr *address, int *value)
+{
+  char *hostname;
+  int ok = 0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(line, "%d", value) != 1) {
+    LOG(LOGS_ERR, "Invalid syntax for address value");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      ok = 1;
+    }
+  }
+
+  return ok;
+
+}
+
+
+/* ================================================== */
+
+static int
+read_address_double(char *line, IPAddr *address, double *value)
+{
+  char *hostname;
+  int ok = 0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(line, "%lf", value) != 1) {
+    LOG(LOGS_ERR, "Invalid syntax for address value");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      ok = 1;
+    }
+  }
+
+  return ok;
+
+}
+
+
+/* ================================================== */
+
+static int
+process_cmd_minpoll(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int minpoll;
+  int ok;
+  
+  if (read_address_integer(line, &address, &minpoll)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_minpoll.address);
+    msg->data.modify_minpoll.new_minpoll = htonl(minpoll);
+    msg->command = htons(REQ_MODIFY_MINPOLL);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxpoll(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int maxpoll;
+  int ok;
+  
+  if (read_address_integer(line, &address, &maxpoll)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxpoll.address);
+    msg->data.modify_maxpoll.new_maxpoll = htonl(maxpoll);
+    msg->command = htons(REQ_MODIFY_MAXPOLL);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelay(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelay.address);
+    msg->data.modify_maxdelay.new_max_delay = UTI_FloatHostToNetwork(max_delay);
+    msg->command = htons(REQ_MODIFY_MAXDELAY);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelaydevratio(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay_dev_ratio;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay_dev_ratio)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelaydevratio.address);
+    msg->data.modify_maxdelayratio.new_max_delay_ratio = UTI_FloatHostToNetwork(max_delay_dev_ratio);
+    msg->command = htons(REQ_MODIFY_MAXDELAYDEVRATIO);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxdelayratio(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  double max_delay_ratio;
+  int ok;
+  
+  if (read_address_double(line, &address, &max_delay_ratio)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_maxdelayratio.address);
+    msg->data.modify_maxdelayratio.new_max_delay_ratio = UTI_FloatHostToNetwork(max_delay_ratio);
+    msg->command = htons(REQ_MODIFY_MAXDELAYRATIO);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_minstratum(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int min_stratum;
+  int ok;
+  
+  if (read_address_integer(line, &address, &min_stratum)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_minstratum.address);
+    msg->data.modify_minstratum.new_min_stratum = htonl(min_stratum);
+    msg->command = htons(REQ_MODIFY_MINSTRATUM);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_polltarget(CMD_Request *msg, char *line)
+{
+  IPAddr address;
+  int poll_target;
+  int ok;
+  
+  if (read_address_integer(line, &address, &poll_target)) {
+    UTI_IPHostToNetwork(&address, &msg->data.modify_polltarget.address);
+    msg->data.modify_polltarget.new_poll_target = htonl(poll_target);
+    msg->command = htons(REQ_MODIFY_POLLTARGET);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static int
+process_cmd_maxupdateskew(CMD_Request *msg, char *line)
+{
+  int ok;
+  double new_max_update_skew;
+  
+  if (sscanf(line, "%lf", &new_max_update_skew) == 1) {
+    msg->data.modify_maxupdateskew.new_max_update_skew = UTI_FloatHostToNetwork(new_max_update_skew);
+    msg->command = htons(REQ_MODIFY_MAXUPDATESKEW);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+
+  return ok;
+
+}
+
+/* ================================================== */
+
+static void
+process_cmd_dump(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_DUMP);
+  msg->data.dump.pad = htonl(0);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_writertc(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_WRITERTC);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_trimrtc(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_TRIMRTC);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_cyclelogs(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_CYCLELOGS);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_burst(CMD_Request *msg, char *line)
+{
+  int n_good_samples, n_total_samples;
+  char *s1, *s2;
+  IPAddr address, mask;
+
+  s1 = line;
+  s2 = CPS_SplitWord(s1);
+  CPS_SplitWord(s2);
+
+  if (sscanf(s1, "%d/%d", &n_good_samples, &n_total_samples) != 2) {
+    LOG(LOGS_ERR, "Invalid syntax for burst command");
+    return 0;
+  }
+
+  mask.family = address.family = IPADDR_UNSPEC;
+  if (*s2 && !read_mask_address(s2, &mask, &address)) {
+    return 0;
+  }
+
+  msg->command = htons(REQ_BURST);
+  msg->data.burst.n_good_samples = ntohl(n_good_samples);
+  msg->data.burst.n_total_samples = ntohl(n_total_samples);
+
+  UTI_IPHostToNetwork(&mask, &msg->data.burst.mask);
+  UTI_IPHostToNetwork(&address, &msg->data.burst.address);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_local(CMD_Request *msg, char *line)
+{
+  int on_off, stratum = 0, orphan = 0;
+  double distance = 0.0;
+
+  if (!strcmp(line, "off")) {
+    on_off = 0;
+  } else if (CPS_ParseLocal(line, &stratum, &orphan, &distance)) {
+    on_off = 1;
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for local command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_LOCAL2);
+  msg->data.local.on_off = htonl(on_off);
+  msg->data.local.stratum = htonl(stratum);
+  msg->data.local.distance = UTI_FloatHostToNetwork(distance);
+  msg->data.local.orphan = htonl(orphan);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_manual(CMD_Request *msg, const char *line)
+{
+  const char *p;
+
+  p = line;
+
+  if (!strcmp(p, "off")) {
+    msg->data.manual.option = htonl(0);
+  } else if (!strcmp(p, "on")) {
+    msg->data.manual.option = htonl(1);
+  } else if (!strcmp(p, "reset")) {
+    msg->data.manual.option = htonl(2);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for manual command");
+    return 0;
+  }
+  msg->command = htons(REQ_MANUAL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_allowdeny(CMD_Request *msg, char *line, int cmd, int allcmd)
+{
+  int all, subnet_bits;
+  IPAddr ip;
+  
+  if (!CPS_ParseAllowDeny(line, &all, &ip, &subnet_bits)) {
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+
+  msg->command = htons(all ? allcmd : cmd);
+  UTI_IPHostToNetwork(&ip, &msg->data.allow_deny.ip);
+  msg->data.allow_deny.subnet_bits = htonl(subnet_bits);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_accheck(CMD_Request *msg, char *line)
+{
+  IPAddr ip;
+  msg->command = htons(REQ_ACCHECK);
+  if (DNS_Name2IPAddress(line, &ip, 1) == DNS_Success) {
+    UTI_IPHostToNetwork(&ip, &msg->data.ac_check.ip);
+    return 1;
+  } else {    
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_cmdaccheck(CMD_Request *msg, char *line)
+{
+  IPAddr ip;
+  msg->command = htons(REQ_CMDACCHECK);
+  if (DNS_Name2IPAddress(line, &ip, 1) == DNS_Success) {
+    UTI_IPHostToNetwork(&ip, &msg->data.ac_check.ip);
+    return 1;
+  } else {    
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_dfreq(CMD_Request *msg, char *line)
+{
+  double dfreq;
+
+  msg->command = htons(REQ_DFREQ);
+
+  if (sscanf(line, "%lf", &dfreq) != 1) {
+    LOG(LOGS_ERR, "Invalid value");
+    return 0;
+  }
+
+  msg->data.dfreq.dfreq = UTI_FloatHostToNetwork(dfreq);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_doffset(CMD_Request *msg, char *line)
+{
+  double doffset;
+
+  msg->command = htons(REQ_DOFFSET2);
+
+  if (sscanf(line, "%lf", &doffset) != 1) {
+    LOG(LOGS_ERR, "Invalid value");
+    return 0;
+  }
+
+  msg->data.doffset.doffset = UTI_FloatHostToNetwork(doffset);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+convert_addsrc_sel_options(int options)
+{
+  return (options & SRC_SELECT_PREFER ? REQ_ADDSRC_PREFER : 0) |
+         (options & SRC_SELECT_NOSELECT ? REQ_ADDSRC_NOSELECT : 0) |
+         (options & SRC_SELECT_TRUST ? REQ_ADDSRC_TRUST : 0) |
+         (options & SRC_SELECT_REQUIRE ? REQ_ADDSRC_REQUIRE : 0);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_add_source(CMD_Request *msg, char *line)
+{
+  CPS_NTP_Source data;
+  IPAddr ip_addr;
+  int result = 0, status, type;
+  const char *opt_name, *word;
+  
+  msg->command = htons(REQ_ADD_SOURCE);
+
+  word = line;
+  line = CPS_SplitWord(line);
+
+  if (!strcasecmp(word, "server")) {
+    type = REQ_ADDSRC_SERVER;
+  } else if (!strcasecmp(word, "peer")) {
+    type = REQ_ADDSRC_PEER;
+  } else if (!strcasecmp(word, "pool")) {
+    type = REQ_ADDSRC_POOL;
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for add command");
+    return 0;
+  }
+
+  status = CPS_ParseNTPSourceAdd(line, &data);
+  switch (status) {
+    case 0:
+      LOG(LOGS_ERR, "Invalid syntax for add command");
+      break;
+    default:
+      /* Verify that the address is resolvable (chronyc and chronyd are
+         assumed to be running on the same host) */
+      if (strlen(data.name) >= sizeof (msg->data.ntp_source.name) ||
+          DNS_Name2IPAddress(data.name, &ip_addr, 1) != DNS_Success) {
+        LOG(LOGS_ERR, "Invalid host/IP address");
+        break;
+      }
+
+      opt_name = NULL;
+      if (opt_name) {
+        LOG(LOGS_ERR, "%s can't be set in chronyc", opt_name);
+        break;
+      }
+
+      msg->data.ntp_source.type = htonl(type);
+      if (strlen(data.name) >= sizeof (msg->data.ntp_source.name))
+        assert(0);
+      strncpy((char *)msg->data.ntp_source.name, data.name,
+              sizeof (msg->data.ntp_source.name));
+      msg->data.ntp_source.port = htonl(data.port);
+      msg->data.ntp_source.minpoll = htonl(data.params.minpoll);
+      msg->data.ntp_source.maxpoll = htonl(data.params.maxpoll);
+      msg->data.ntp_source.presend_minpoll = htonl(data.params.presend_minpoll);
+      msg->data.ntp_source.min_stratum = htonl(data.params.min_stratum);
+      msg->data.ntp_source.poll_target = htonl(data.params.poll_target);
+      msg->data.ntp_source.version = htonl(data.params.version);
+      msg->data.ntp_source.max_sources = htonl(data.params.max_sources);
+      msg->data.ntp_source.min_samples = htonl(data.params.min_samples);
+      msg->data.ntp_source.max_samples = htonl(data.params.max_samples);
+      msg->data.ntp_source.authkey = htonl(data.params.authkey);
+      msg->data.ntp_source.nts_port = htonl(data.params.nts_port);
+      msg->data.ntp_source.max_delay = UTI_FloatHostToNetwork(data.params.max_delay);
+      msg->data.ntp_source.max_delay_ratio = UTI_FloatHostToNetwork(data.params.max_delay_ratio);
+      msg->data.ntp_source.max_delay_dev_ratio =
+        UTI_FloatHostToNetwork(data.params.max_delay_dev_ratio);
+      msg->data.ntp_source.min_delay = UTI_FloatHostToNetwork(data.params.min_delay);
+      msg->data.ntp_source.asymmetry = UTI_FloatHostToNetwork(data.params.asymmetry);
+      msg->data.ntp_source.offset = UTI_FloatHostToNetwork(data.params.offset);
+      msg->data.ntp_source.flags = htonl(
+          (data.params.connectivity == SRC_ONLINE ? REQ_ADDSRC_ONLINE : 0) |
+          (data.params.auto_offline ? REQ_ADDSRC_AUTOOFFLINE : 0) |
+          (data.params.iburst ? REQ_ADDSRC_IBURST : 0) |
+          (data.params.interleaved ? REQ_ADDSRC_INTERLEAVED : 0) |
+          (data.params.burst ? REQ_ADDSRC_BURST : 0) |
+          (data.params.nts ? REQ_ADDSRC_NTS : 0) |
+          (data.params.copy ? REQ_ADDSRC_COPY : 0) |
+          (data.params.ext_fields & NTP_EF_FLAG_EXP1 ? REQ_ADDSRC_EF_EXP1 : 0) |
+          convert_addsrc_sel_options(data.params.sel_options));
+      msg->data.ntp_source.filter_length = htonl(data.params.filter_length);
+      msg->data.ntp_source.cert_set = htonl(data.params.cert_set);
+      msg->data.ntp_source.max_delay_quant =
+        UTI_FloatHostToNetwork(data.params.max_delay_quant);
+      memset(msg->data.ntp_source.reserved, 0, sizeof (msg->data.ntp_source.reserved));
+
+      result = 1;
+
+      break;
+  }
+
+  return result;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_delete(CMD_Request *msg, char *line)
+{
+  char *hostname;
+  int ok = 0;
+  IPAddr address;
+
+  msg->command = htons(REQ_DEL_SOURCE);
+  hostname = line;
+  CPS_SplitWord(line);
+
+  if (!*hostname) {
+    LOG(LOGS_ERR, "Invalid syntax for address");
+    ok = 0;
+  } else {
+    if (!parse_source_address(hostname, &address)) {
+      LOG(LOGS_ERR, "Could not get address for hostname");
+      ok = 0;
+    } else {
+      UTI_IPHostToNetwork(&address, &msg->data.del_source.ip_addr);
+      ok = 1;
+    }
+  }
+
+  return ok;
+  
+}
+
+/* ================================================== */
+
+static void
+give_help(void)
+{
+  int line, len;
+  const char *s, cols[] =
+    "System clock:\0\0"
+    "tracking\0Display system time information\0"
+    "makestep\0Correct clock by stepping immediately\0"
+    "makestep <threshold> <updates>\0Configure automatic clock stepping\0"
+    "maxupdateskew <skew>\0Modify maximum valid skew to update frequency\0"
+    "waitsync [<max-tries> [<max-correction> [<max-skew> [<interval>]]]]\0"
+                          "Wait until synchronised in specified limits\0"
+    "\0\0"
+    "Time sources:\0\0"
+    "sources [-a] [-v]\0Display information about current sources\0"
+    "sourcestats [-a] [-v]\0Display statistics about collected measurements\0"
+    "selectdata [-a] [-v]\0Display information about source selection\0"
+    "selectopts <address|refid> <+|-options>\0Modify selection options\0"
+    "reselect\0Force reselecting synchronisation source\0"
+    "reselectdist <dist>\0Modify reselection distance\0"
+    "\0\0"
+    "NTP sources:\0\0"
+    "activity\0Check how many NTP sources are online/offline\0"
+    "authdata [-a] [-v]\0Display information about authentication\0"
+    "ntpdata [<address>]\0Display information about last valid measurement\0"
+    "add server <name> [options]\0Add new NTP server\0"
+    "add pool <name> [options]\0Add new pool of NTP servers\0"
+    "add peer <name> [options]\0Add new NTP peer\0"
+    "delete <address>\0Remove server or peer\0"
+    "burst <n-good>/<n-max> [[<mask>/]<address>]\0Start rapid set of measurements\0"
+    "maxdelay <address> <delay>\0Modify maximum valid sample delay\0"
+    "maxdelayratio <address> <ratio>\0Modify maximum valid delay/minimum ratio\0"
+    "maxdelaydevratio <address> <ratio>\0Modify maximum valid delay/deviation ratio\0"
+    "minpoll <address> <poll>\0Modify minimum polling interval\0"
+    "maxpoll <address> <poll>\0Modify maximum polling interval\0"
+    "minstratum <address> <stratum>\0Modify minimum stratum\0"
+    "offline [[<mask>/]<address>]\0Set sources in subnet to offline status\0"
+    "online [[<mask>/]<address>]\0Set sources in subnet to online status\0"
+    "onoffline\0Set all sources to online or offline status\0"
+    "\0according to network configuration\0"
+    "polltarget <address> <target>\0Modify poll target\0"
+    "refresh\0Refresh IP addresses\0"
+    "reload sources\0Re-read *.sources files\0"
+    "sourcename <address>\0Display original name\0"
+    "\0\0"
+    "Manual time input:\0\0"
+    "manual off|on|reset\0Disable/enable/reset settime command\0"
+    "manual list\0Show previous settime entries\0"
+    "manual delete <index>\0Delete previous settime entry\0"
+    "settime <time>\0Set daemon time\0"
+    "\0(e.g. Sep 25, 2015 16:30:05 or 16:30:05)\0"
+    "\0\0NTP access:\0\0"
+    "accheck <address>\0Check whether address is allowed\0"
+    "clients [-p <packets>] [-k] [-r]\0Report on clients that accessed the server\0"
+    "serverstats\0Display statistics of the server\0"
+    "allow [<subnet>]\0Allow access to subnet as a default\0"
+    "allow all [<subnet>]\0Allow access to subnet and all children\0"
+    "deny [<subnet>]\0Deny access to subnet as a default\0"
+    "deny all [<subnet>]\0Deny access to subnet and all children\0"
+    "local [options]\0Serve time even when not synchronised\0"
+    "local off\0Don't serve time when not synchronised\0"
+    "smoothtime reset|activate\0Reset/activate time smoothing\0"
+    "smoothing\0Display current time smoothing state\0"
+    "\0\0"
+    "Monitoring access:\0\0"
+    "cmdaccheck <address>\0Check whether address is allowed\0"
+    "cmdallow [<subnet>]\0Allow access to subnet as a default\0"
+    "cmdallow all [<subnet>]\0Allow access to subnet and all children\0"
+    "cmddeny [<subnet>]\0Deny access to subnet as a default\0"
+    "cmddeny all [<subnet>]\0Deny access to subnet and all children\0"
+    "\0\0"
+    "Real-time clock:\0\0"
+    "rtcdata\0Print current RTC performance parameters\0"
+    "trimrtc\0Correct RTC relative to system clock\0"
+    "writertc\0Save RTC performance parameters to file\0"
+    "\0\0"
+    "Other daemon commands:\0\0"
+    "cyclelogs\0Close and re-open log files\0"
+    "dump\0Dump measurements and NTS keys/cookies\0"
+    "rekey\0Re-read keys\0"
+    "reset sources\0Drop all measurements\0"
+    "shutdown\0Stop daemon\0"
+    "\0\0"
+    "Client commands:\0\0"
+    "dns -n|+n\0Disable/enable resolving IP addresses to hostnames\0"
+    "dns -4|-6|-46\0Resolve hostnames only to IPv4/IPv6/both addresses\0"
+    "timeout <milliseconds>\0Set initial response timeout\0"
+    "retries <retries>\0Set maximum number of retries\0"
+    "keygen [<id> [<type> [<bits>]]]\0Generate key for key file\0"
+    "exit|quit\0Leave the program\0"
+    "help\0Generate this help\0"
+    "\0";
+
+  /* Indent the second column */
+  for (s = cols, line = 0; s < cols + sizeof (cols); s += len + 1, line++) {
+    len = strlen(s);
+    printf(line % 2 == 0 ? (len >= 28 ? "%s\n%28s" : "%-28s%s") : "%s%s\n",
+           s, "");
+  }
+}
+
+/* ================================================== */
+/* Tab-completion when editline is available */
+
+#ifdef FEAT_READLINE
+
+enum {
+  TAB_COMPLETE_BASE_CMDS,
+  TAB_COMPLETE_ADD_OPTS,
+  TAB_COMPLETE_MANUAL_OPTS,
+  TAB_COMPLETE_RELOAD_OPTS,
+  TAB_COMPLETE_RESET_OPTS,
+  TAB_COMPLETE_SOURCES_OPTS,
+  TAB_COMPLETE_SOURCESTATS_OPTS,
+  TAB_COMPLETE_AUTHDATA_OPTS,
+  TAB_COMPLETE_SELECTDATA_OPTS,
+  TAB_COMPLETE_MAX_INDEX
+};
+
+static int tab_complete_index;
+
+static char *
+command_name_generator(const char *text, int state)
+{
+  const char *name, **names[TAB_COMPLETE_MAX_INDEX];
+  const char *base_commands[] = {
+    "accheck", "activity", "add", "allow", "authdata", "burst",
+    "clients", "cmdaccheck", "cmdallow", "cmddeny", "cyclelogs", "delete",
+    "deny", "dns", "dump", "exit", "help", "keygen", "local", "makestep",
+    "manual", "maxdelay", "maxdelaydevratio", "maxdelayratio", "maxpoll",
+    "maxupdateskew", "minpoll", "minstratum", "ntpdata", "offline", "online", "onoffline",
+    "polltarget", "quit", "refresh", "rekey", "reload", "reselect", "reselectdist", "reset",
+    "retries", "rtcdata", "selectdata", "selectopts", "serverstats", "settime",
+    "shutdown", "smoothing", "smoothtime", "sourcename", "sources", "sourcestats",
+    "timeout", "tracking", "trimrtc", "waitsync", "writertc",
+    NULL
+  };
+  const char *add_options[] = { "peer", "pool", "server", NULL };
+  const char *manual_options[] = { "on", "off", "delete", "list", "reset", NULL };
+  const char *reset_options[] = { "sources", NULL };
+  const char *reload_options[] = { "sources", NULL };
+  const char *common_source_options[] = { "-a", "-v", NULL };
+  static int list_index, len;
+
+  names[TAB_COMPLETE_BASE_CMDS] = base_commands;
+  names[TAB_COMPLETE_ADD_OPTS] = add_options;
+  names[TAB_COMPLETE_MANUAL_OPTS] = manual_options;
+  names[TAB_COMPLETE_RELOAD_OPTS] = reload_options;
+  names[TAB_COMPLETE_RESET_OPTS] = reset_options;
+  names[TAB_COMPLETE_AUTHDATA_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SELECTDATA_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SOURCES_OPTS] = common_source_options;
+  names[TAB_COMPLETE_SOURCESTATS_OPTS] = common_source_options;
+
+  if (!state) {
+    list_index = 0;
+    len = strlen(text);
+  }
+
+  while ((name = names[tab_complete_index][list_index++])) {
+    if (strncmp(name, text, len) == 0) {
+      return Strdup(name);
+    }
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static char **
+command_name_completion(const char *text, int start, int end)
+{
+  char first[32];
+
+  snprintf(first, MIN(sizeof (first), start + 1), "%s", rl_line_buffer);
+  rl_attempted_completion_over = 1;
+
+  if (!strcmp(first, "add ")) {
+    tab_complete_index = TAB_COMPLETE_ADD_OPTS;
+  } else if (!strcmp(first, "authdata ")) {
+    tab_complete_index = TAB_COMPLETE_AUTHDATA_OPTS;
+  } else if (!strcmp(first, "manual ")) {
+    tab_complete_index = TAB_COMPLETE_MANUAL_OPTS;
+  } else if (!strcmp(first, "reload ")) {
+    tab_complete_index = TAB_COMPLETE_RELOAD_OPTS;
+  } else if (!strcmp(first, "reset ")) {
+    tab_complete_index = TAB_COMPLETE_RESET_OPTS;
+  } else if (!strcmp(first, "selectdata ")) {
+    tab_complete_index = TAB_COMPLETE_SELECTDATA_OPTS;
+  } else if (!strcmp(first, "sources ")) {
+    tab_complete_index = TAB_COMPLETE_SOURCES_OPTS;
+  } else if (!strcmp(first, "sourcestats ")) {
+    tab_complete_index = TAB_COMPLETE_SOURCESTATS_OPTS;
+  } else if (first[0] == '\0') {
+    tab_complete_index = TAB_COMPLETE_BASE_CMDS;
+  } else {
+    return NULL;
+  }
+
+  return rl_completion_matches(text, command_name_generator);
+}
+#endif
+
+/* ================================================== */
+
+static int max_retries = 2;
+static int initial_timeout = 1000;
+static int proto_version = PROTO_VERSION_NUMBER;
+
+/* This is the core protocol module.  Complete particular fields in
+   the outgoing packet, send it, wait for a response, handle retries,
+   etc.  Returns a Boolean indicating whether the protocol was
+   successful or not.*/
+
+static int
+submit_request(CMD_Request *request, CMD_Reply *reply)
+{
+  int select_status;
+  int recv_status;
+  int read_length;
+  int command_length;
+  int padding_length;
+  struct timespec ts_now, ts_start;
+  struct timeval tv;
+  int n_attempts, new_attempt;
+  double timeout;
+  fd_set rdfd;
+
+  request->pkt_type = PKT_TYPE_CMD_REQUEST;
+  request->res1 = 0;
+  request->res2 = 0;
+  request->pad1 = 0;
+  request->pad2 = 0;
+
+  n_attempts = 0;
+  new_attempt = 1;
+
+  do {
+    if (gettimeofday(&tv, NULL))
+      return 0;
+
+    if (new_attempt) {
+      new_attempt = 0;
+
+      if (n_attempts > max_retries)
+        return 0;
+
+      UTI_TimevalToTimespec(&tv, &ts_start);
+
+      UTI_GetRandomBytes(&request->sequence, sizeof (request->sequence));
+      request->attempt = htons(n_attempts);
+      request->version = proto_version;
+      command_length = PKL_CommandLength(request);
+      padding_length = PKL_CommandPaddingLength(request);
+      assert(command_length > 0 && command_length > padding_length);
+
+      n_attempts++;
+
+      /* Zero the padding to not send any uninitialized data */
+      memset(((char *)request) + command_length - padding_length, 0, padding_length);
+
+      if (sock_fd < 0) {
+        DEBUG_LOG("No socket to send request");
+        return 0;
+      }
+
+      if (SCK_Send(sock_fd, (void *)request, command_length, 0) < 0)
+        return 0;
+    }
+
+    UTI_TimevalToTimespec(&tv, &ts_now);
+
+    /* Check if the clock wasn't stepped back */
+    if (UTI_CompareTimespecs(&ts_now, &ts_start) < 0)
+      ts_start = ts_now;
+
+    timeout = initial_timeout / 1000.0 * (1U << (n_attempts - 1)) -
+              UTI_DiffTimespecsToDouble(&ts_now, &ts_start);
+    DEBUG_LOG("Timeout %f seconds", timeout);
+
+    /* Avoid calling select() with an invalid timeout */
+    if (timeout <= 0.0) {
+      new_attempt = 1;
+      continue;
+    }
+
+    UTI_DoubleToTimeval(timeout, &tv);
+
+    FD_ZERO(&rdfd);
+    FD_SET(sock_fd, &rdfd);
+
+    if (quit)
+      return 0;
+
+    select_status = select(sock_fd + 1, &rdfd, NULL, NULL, &tv);
+
+    if (select_status < 0) {
+      DEBUG_LOG("select failed : %s", strerror(errno));
+      return 0;
+    } else if (select_status == 0) {
+      /* Timeout must have elapsed, try a resend? */
+      new_attempt = 1;
+    } else {
+      recv_status = SCK_Receive(sock_fd, reply, sizeof (*reply), 0);
+      
+      if (recv_status < 0) {
+        new_attempt = 1;
+      } else {
+        read_length = recv_status;
+        
+        /* Check if the header is valid */
+        if (read_length < offsetof(CMD_Reply, data) ||
+            (reply->version != proto_version &&
+             !(reply->version >= PROTO_VERSION_MISMATCH_COMPAT_CLIENT &&
+               ntohs(reply->status) == STT_BADPKTVERSION)) ||
+            reply->pkt_type != PKT_TYPE_CMD_REPLY ||
+            reply->res1 != 0 ||
+            reply->res2 != 0 ||
+            reply->command != request->command ||
+            reply->sequence != request->sequence) {
+          DEBUG_LOG("Invalid reply");
+          continue;
+        }
+        
+#if PROTO_VERSION_NUMBER == 6
+        /* Protocol version 5 is similar to 6 except there is no padding.
+           If a version 5 reply with STT_BADPKTVERSION is received,
+           switch our version and try again. */
+        if (proto_version == PROTO_VERSION_NUMBER &&
+            reply->version == PROTO_VERSION_NUMBER - 1) {
+          proto_version = PROTO_VERSION_NUMBER - 1;
+          n_attempts--;
+          new_attempt = 1;
+          continue;
+        }
+#else
+#error unknown compatibility with PROTO_VERSION - 1
+#endif
+
+        /* Check that the packet contains all data it is supposed to have.
+           Unknown responses will always pass this test as their expected
+           length is zero. */
+        if (read_length < PKL_ReplyLength(reply)) {
+          DEBUG_LOG("Reply too short");
+          new_attempt = 1;
+          continue;
+        }
+
+        /* Good packet received, print out results */
+        DEBUG_LOG("Reply cmd=%d reply=%d stat=%d",
+                  ntohs(reply->command), ntohs(reply->reply), ntohs(reply->status));
+        break;
+      }
+    }
+  } while (1);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+request_reply(CMD_Request *request, CMD_Reply *reply, int requested_reply, int verbose)
+{
+  int status;
+
+  while (!submit_request(request, reply)) {
+    /* Try connecting to other addresses before giving up */
+    if (open_io())
+      continue;
+    printf("506 Cannot talk to daemon\n");
+    return 0;
+  }
+
+  status = ntohs(reply->status);
+        
+  if (verbose || status != STT_SUCCESS) {
+    switch (status) {
+      case STT_SUCCESS:
+        printf("200 OK");
+        break;
+      case STT_ACCESSALLOWED:
+        printf("208 Access allowed");
+        break;
+      case STT_ACCESSDENIED:
+        printf("209 Access denied");
+        break;
+      case STT_FAILED:
+        printf("500 Failure");
+        break;
+      case STT_UNAUTH:
+        printf("501 Not authorised");
+        break;
+      case STT_INVALID:
+        printf("502 Invalid command");
+        break;
+      case STT_NOSUCHSOURCE:
+        printf("503 No such source");
+        break;
+      case STT_INVALIDTS:
+        printf("504 Duplicate or stale logon detected");
+        break;
+      case STT_NOTENABLED:
+        printf("505 Facility not enabled in daemon");
+        break;
+      case STT_BADSUBNET:
+        printf("507 Bad subnet");
+        break;
+      case STT_NOHOSTACCESS:
+        printf("510 No command access from this host");
+        break;
+      case STT_SOURCEALREADYKNOWN:
+        printf("511 Source already present");
+        break;
+      case STT_TOOMANYSOURCES:
+        printf("512 Too many sources present");
+        break;
+      case STT_NORTC:
+        printf("513 RTC driver not running");
+        break;
+      case STT_BADRTCFILE:
+        printf("514 Can't write RTC parameters");
+        break;
+      case STT_INVALIDAF:
+        printf("515 Invalid address family");
+        break;
+      case STT_BADSAMPLE:
+        printf("516 Sample index out of range");
+        break;
+      case STT_BADPKTVERSION:
+        printf("517 Protocol version mismatch");
+        break;
+      case STT_BADPKTLENGTH:
+        printf("518 Packet length mismatch");
+        break;
+      case STT_INACTIVE:
+        printf("519 Client logging is not active in the daemon");
+        break;
+      case STT_INVALIDNAME:
+        printf("521 Invalid name");
+        break;
+      default:
+        printf("520 Got unexpected error from daemon");
+    }
+    printf("\n");
+  }
+  
+  if (status != STT_SUCCESS &&
+      status != STT_ACCESSALLOWED && status != STT_ACCESSDENIED) {
+    return 0;
+  } 
+
+  if (ntohs(reply->reply) != requested_reply) {
+    printf("508 Bad reply from daemon\n");
+    return 0;
+  }
+
+  /* Make sure an unknown response was not requested */
+  assert(PKL_ReplyLength(reply));
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+print_seconds(uint32_t s)
+{
+  uint32_t d;
+
+  if (s == (uint32_t)-1) {
+    printf("   -");
+  } else if (s < 1200) {
+    printf("%4"PRIu32, s);
+  } else if (s < 36000) {
+    printf("%3"PRIu32"m", s / 60);
+  } else if (s < 345600) {
+    printf("%3"PRIu32"h", s / 3600);
+  } else {
+    d = s / 86400;
+    if (d > 999) {
+      printf("%3"PRIu32"y", d / 365);
+    } else {
+      printf("%3"PRIu32"d", d);
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+print_nanoseconds(double s)
+{
+  s = fabs(s);
+
+  if (s < 9999.5e-9) {
+    printf("%4.0fns", s * 1e9);
+  } else if (s < 9999.5e-6) {
+    printf("%4.0fus", s * 1e6);
+  } else if (s < 9999.5e-3) {
+    printf("%4.0fms", s * 1e3);
+  } else if (s < 999.5) {
+    printf("%5.1fs", s);
+  } else if (s < 99999.5) {
+    printf("%5.0fs", s);
+  } else if (s < 99999.5 * 60) {
+    printf("%5.0fm", s / 60);
+  } else if (s < 99999.5 * 3600) {
+    printf("%5.0fh", s / 3600);
+  } else if (s < 99999.5 * 3600 * 24) {
+    printf("%5.0fd", s / (3600 * 24));
+  } else {
+    printf("%5.0fy", s / (3600 * 24 * 365));
+  }
+}
+
+/* ================================================== */
+
+static void
+print_signed_nanoseconds(double s)
+{
+  double x;
+
+  x = fabs(s);
+
+  if (x < 9999.5e-9) {
+    printf("%+5.0fns", s * 1e9);
+  } else if (x < 9999.5e-6) {
+    printf("%+5.0fus", s * 1e6);
+  } else if (x < 9999.5e-3) {
+    printf("%+5.0fms", s * 1e3);
+  } else if (x < 999.5) {
+    printf("%+6.1fs", s);
+  } else if (x < 99999.5) {
+    printf("%+6.0fs", s);
+  } else if (x < 99999.5 * 60) {
+    printf("%+6.0fm", s / 60);
+  } else if (x < 99999.5 * 3600) {
+    printf("%+6.0fh", s / 3600);
+  } else if (x < 99999.5 * 3600 * 24) {
+    printf("%+6.0fd", s / (3600 * 24));
+  } else {
+    printf("%+6.0fy", s / (3600 * 24 * 365));
+  }
+}
+
+/* ================================================== */
+
+static void
+print_freq_ppm(double f)
+{
+  if (fabs(f) < 99999.5) {
+    printf("%10.3f", f);
+  } else {
+    printf("%10.0f", f);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_signed_freq_ppm(double f)
+{
+  if (fabs(f) < 99999.5) {
+    printf("%+10.3f", f);
+  } else {
+    printf("%+10.0f", f);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_clientlog_interval(int rate)
+{
+  if (rate >= 127) {
+    printf(" -");
+  } else {
+    printf("%2d", rate);
+  }
+}
+
+/* ================================================== */
+
+static void
+print_header(const char *header)
+{
+  int len;
+
+  if (csv_mode)
+    return;
+
+  printf("%s\n", header);
+
+  len = strlen(header);
+  while (len--)
+    printf("=");
+  printf("\n");
+}
+
+/* ================================================== */
+
+#define REPORT_END 0x1234
+
+/* Print a report. The syntax of the format is similar to printf(), but not all
+   specifiers are supported and some are different! */
+
+static void
+print_report(const char *format, ...)
+{
+  char buf[256];
+  va_list ap;
+  int i, field, sign, width, prec, spec;
+  const char *string;
+  unsigned int uinteger;
+  uint64_t uinteger64;
+  uint32_t uinteger32;
+  int integer;
+  struct timespec *ts;
+  struct tm *tm;
+  double dbl;
+
+  va_start(ap, format);
+
+  for (field = 0; ; field++) {
+    /* Search for text between format specifiers and print it
+       if not in the CSV mode */
+    for (i = 0; i < sizeof (buf) && format[i] != '%' && format[i] != '\0'; i++)
+      buf[i] = format[i];
+
+    if (i >= sizeof (buf))
+      break;
+
+    buf[i] = '\0';
+
+    if (!csv_mode)
+      printf("%s", buf);
+
+    if (format[i] == '\0' || format[i + 1] == '\0')
+      break;
+
+    format += i + 1;
+
+    sign = 0;
+    width = 0;
+    prec = 5;
+
+    if (*format == '+' || *format == '-') {
+      sign = 1;
+      format++;
+    }
+
+    if (isdigit((unsigned char)*format)) {
+      width = atoi(format);
+      while (isdigit((unsigned char)*format))
+        format++;
+    }
+
+    if (*format == '.') {
+      format++;
+      prec = atoi(format);
+      while (isdigit((unsigned char)*format))
+        format++;
+    }
+
+    spec = *format;
+    format++;
+
+    /* Disable human-readable formatting in the CSV mode */
+    if (csv_mode) {
+      sign = width = 0;
+
+      if (field > 0)
+        printf(",");
+
+      switch (spec) {
+        case 'C':
+          spec = 'd';
+          break;
+        case 'F':
+        case 'P':
+          prec = 3;
+          spec = 'f';
+          break;
+        case 'O':
+        case 'S':
+          prec = 9;
+          spec = 'f';
+          break;
+        case 'I':
+          spec = 'U';
+          break;
+        case 'T':
+          spec = 'V';
+          break;
+      }
+    }
+
+    switch (spec) {
+      case 'B': /* boolean */
+        integer = va_arg(ap, int);
+        printf("%s", integer ? "Yes" : "No");
+        break;
+      case 'C': /* clientlog interval */
+        integer = va_arg(ap, int);
+        print_clientlog_interval(integer);
+        break;
+      case 'F': /* absolute frequency in ppm with fast/slow keyword */
+      case 'O': /* absolute offset in seconds with fast/slow keyword */
+        dbl = va_arg(ap, double);
+        printf("%*.*f %s %s", width, prec, fabs(dbl),
+               spec == 'O' ? "seconds" : "ppm",
+               (dbl > 0.0) ^ (spec != 'O') ? "slow" : "fast");
+        break;
+      case 'I': /* uint32_t interval with unit */
+        uinteger32 = va_arg(ap, uint32_t);
+        print_seconds(uinteger32);
+        break;
+      case 'L': /* leap status */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case LEAP_Normal:
+            string = width != 1 ? "Normal" : "N";
+            break;
+          case LEAP_InsertSecond:
+            string = width != 1 ? "Insert second" : "+";
+            break;
+          case LEAP_DeleteSecond:
+            string = width != 1 ? "Delete second" : "-";
+            break;
+          case LEAP_Unsynchronised:
+            string = width != 1 ? "Not synchronised" : "?";
+            break;
+          default:
+            string = width != 1 ? "Invalid" : "?";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'M': /* NTP mode */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case MODE_ACTIVE:
+            string = "Symmetric active";
+            break;
+          case MODE_PASSIVE:
+            string = "Symmetric passive";
+            break;
+          case MODE_SERVER:
+            string = "Server";
+            break;
+          default:
+            string = "Invalid";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'N': /* Timestamp source */
+        integer = va_arg(ap, int);
+        switch (integer) {
+          case 'D':
+            string = "Daemon";
+            break;
+          case 'K':
+            string = "Kernel";
+            break;
+          case 'H':
+            string = "Hardware";
+            break;
+          default:
+            string = "Invalid";
+            break;
+        }
+        printf("%s", string);
+        break;
+      case 'P': /* frequency in ppm */
+        dbl = va_arg(ap, double);
+        if (sign)
+          print_signed_freq_ppm(dbl);
+        else
+          print_freq_ppm(dbl);
+        break;
+      case 'R': /* reference ID in hexdecimal */
+        uinteger32 = va_arg(ap, uint32_t);
+        printf("%08"PRIX32, uinteger32);
+        break;
+      case 'S': /* offset with unit */
+        dbl = va_arg(ap, double);
+        if (sign)
+          print_signed_nanoseconds(dbl);
+        else
+          print_nanoseconds(dbl);
+        break;
+      case 'T': /* timespec as date and time in UTC */
+        ts = va_arg(ap, struct timespec *);
+        tm = gmtime(&ts->tv_sec);
+        if (!tm)
+          break;
+        strftime(buf, sizeof (buf), "%a %b %d %T %Y", tm);
+        printf("%s", buf);
+        break;
+      case 'U': /* uint32_t in decimal */
+        uinteger32 = va_arg(ap, uint32_t);
+        printf("%*"PRIu32, width, uinteger32);
+        break;
+      case 'V': /* timespec as seconds since epoch */
+        ts = va_arg(ap, struct timespec *);
+        printf("%s", UTI_TimespecToString(ts));
+        break;
+      case 'Q': /* uint64_t in decimal */
+        uinteger64 = va_arg(ap, uint64_t);
+        printf("%*"PRIu64, width, uinteger64);
+        break;
+      case 'b': /* unsigned int in binary */
+        uinteger = va_arg(ap, unsigned int);
+        for (i = prec - 1; i >= 0; i--)
+          printf("%c", uinteger & 1U << i ? '1' : '0');
+        break;
+
+      /* Classic printf specifiers */
+      case 'c': /* character */
+        integer = va_arg(ap, int);
+        printf("%c", integer);
+        break;
+      case 'd': /* signed int in decimal */
+        integer = va_arg(ap, int);
+        printf("%*d", width, integer);
+        break;
+      case 'f': /* double */
+        dbl = va_arg(ap, double);
+        printf(sign ? "%+*.*f" : "%*.*f", width, prec, dbl);
+        break;
+      case 'o': /* unsigned int in octal */
+        uinteger = va_arg(ap, unsigned int);
+        printf("%*o", width, uinteger);
+        break;
+      case 's': /* string */
+        string = va_arg(ap, const char *);
+        if (sign)
+          printf("%-*s", width, string);
+        else
+          printf("%*s", width, string);
+        break;
+      case 'u': /* unsigned int in decimal */
+        uinteger = va_arg(ap, unsigned int);
+        printf("%*u", width, uinteger);
+        break;
+    }
+  }
+
+  /* Require terminating argument to catch bad type conversions */
+  if (va_arg(ap, int) != REPORT_END)
+    assert(0);
+
+  va_end(ap);
+
+  if (csv_mode)
+    printf("\n");
+}
+
+/* ================================================== */
+
+static void
+print_info_field(const char *format, ...)
+{
+  va_list ap;
+
+  if (csv_mode)
+    return;
+
+  va_start(ap, format);
+  vprintf(format, ap);
+  va_end(ap);
+}
+
+/* ================================================== */
+
+static int
+get_source_name(IPAddr *ip_addr, char *buf, int size)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  int i;
+
+  request.command = htons(REQ_NTP_SOURCE_NAME);
+  UTI_IPHostToNetwork(ip_addr, &request.data.ntp_source_name.ip_addr);
+  if (!request_reply(&request, &reply, RPY_NTP_SOURCE_NAME, 0) ||
+      reply.data.ntp_source_name.name[sizeof (reply.data.ntp_source_name.name) - 1] != '\0' ||
+      snprintf(buf, size, "%s", (char *)reply.data.ntp_source_name.name) >= size)
+    return 0;
+
+  /* Make sure the name is printable */
+  for (i = 0; i < size && buf[i] != '\0'; i++) {
+    if (!isgraph((unsigned char)buf[i]))
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+format_name(char *buf, int size, int trunc_dns, int ref, uint32_t ref_id,
+            int source, IPAddr *ip_addr)
+{
+  if (ref) {
+    snprintf(buf, size, "%s", UTI_RefidToString(ref_id));
+  } else if (source && source_names) {
+    if (!get_source_name(ip_addr, buf, size))
+      snprintf(buf, size, "?");
+  } else if (no_dns || csv_mode) {
+    snprintf(buf, size, "%s", UTI_IPToString(ip_addr));
+  } else {
+    DNS_IPAddress2Name(ip_addr, buf, size);
+    if (trunc_dns > 0 && strlen(buf) > trunc_dns) {
+      buf[trunc_dns - 1] = '>';
+      buf[trunc_dns] = '\0';
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_sources_options(char *line, int *all, int *verbose)
+{
+  char *opt;
+
+  *all = *verbose = 0;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (!strcmp(opt, "-a"))
+      *all = 1;
+    else if (!strcmp(opt, "-v"))
+      *verbose = !csv_mode;
+  }
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sourcename(char *line)
+{
+  IPAddr ip_addr;
+  char name[256];
+
+  if (!parse_source_address(line, &ip_addr)) {
+    LOG(LOGS_ERR, "Could not read address");
+    return 0;
+  }
+
+  if (!get_source_name(&ip_addr, name, sizeof (name)))
+    return 0;
+
+  print_report("%s\n", name, REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sources(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t i, mode, n_sources;
+  char name[256], mode_ch, state_ch;
+  int all, verbose, ref;
+
+  parse_sources_options(line, &all, &verbose);
+  
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf("\n");
+    printf("  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.\n");
+    printf(" / .- Source state '*' = current best, '+' = combined, '-' = not combined,\n");
+    printf("| /             'x' = may be in error, '~' = too variable, '?' = unusable.\n");
+    printf("||                                                 .- xxxx [ yyyy ] +/- zzzz\n");
+    printf("||      Reachability register (octal) -.           |  xxxx = adjusted offset,\n");
+    printf("||      Log2(Polling interval) --.      |          |  yyyy = measured offset,\n");
+    printf("||                                \\     |          |  zzzz = estimated error.\n");
+    printf("||                                 |    |           \\\n");
+  }
+
+  print_header("MS Name/IP address         Stratum Poll Reach LastRx Last sample               ");
+
+  /*           "MS NNNNNNNNNNNNNNNNNNNNNNNNNNN  SS  PP   RRR  RRRR  SSSSSSS[SSSSSSS] +/- SSSSSS" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCE_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+      return 0;
+
+    mode = ntohs(reply.data.source_data.mode);
+    UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    ref = mode == RPY_SD_MD_REF && ip_addr.family == IPADDR_INET4;
+    format_name(name, sizeof (name), 25, ref, ref ? ip_addr.addr.in4 : 0, 1, &ip_addr);
+
+    switch (mode) {
+      case RPY_SD_MD_CLIENT:
+        mode_ch = '^';
+        break;
+      case RPY_SD_MD_PEER:
+        mode_ch = '=';
+        break;
+      case RPY_SD_MD_REF:
+        mode_ch = '#';
+        break;
+      default:
+        mode_ch = ' ';
+    }
+
+    switch (ntohs(reply.data.source_data.state)) {
+      case RPY_SD_ST_SELECTED:
+        state_ch = '*';
+        break;
+      case RPY_SD_ST_NONSELECTABLE:
+        state_ch = '?';
+        break;
+      case RPY_SD_ST_FALSETICKER:
+        state_ch = 'x';
+        break;
+      case RPY_SD_ST_JITTERY:
+        state_ch = '~';
+        break;
+      case RPY_SD_ST_UNSELECTED:
+        state_ch = '+';
+        break;
+      case RPY_SD_ST_SELECTABLE:
+        state_ch = '-';
+        break;
+      default:
+        state_ch = ' ';
+    }
+
+    switch (ntohs(reply.data.source_data.flags)) {
+      default:
+        break;
+    }
+
+    print_report("%c%c %-27s  %2d  %2d   %3o  %I  %+S[%+S] +/- %S\n",
+                 mode_ch, state_ch, name,
+                 ntohs(reply.data.source_data.stratum),
+                 (int16_t)ntohs(reply.data.source_data.poll),
+                 ntohs(reply.data.source_data.reachability),
+                 ntohl(reply.data.source_data.since_sample),
+                 UTI_FloatNetworkToHost(reply.data.source_data.latest_meas),
+                 UTI_FloatNetworkToHost(reply.data.source_data.orig_latest_meas),
+                 UTI_FloatNetworkToHost(reply.data.source_data.latest_meas_err),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_sourcestats(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_sources;
+  int all, verbose;
+  char name[256];
+  IPAddr ip_addr;
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf("                             .- Number of sample points in measurement set.\n");
+    printf("                            /    .- Number of residual runs with same sign.\n");
+    printf("                           |    /    .- Length of measurement set (time).\n");
+    printf("                           |   |    /      .- Est. clock freq error (ppm).\n");
+    printf("                           |   |   |      /           .- Est. error in freq.\n");
+    printf("                           |   |   |     |           /         .- Est. offset.\n");
+    printf("                           |   |   |     |          |          |   On the -.\n");
+    printf("                           |   |   |     |          |          |   samples. \\\n");
+    printf("                           |   |   |     |          |          |             |\n");
+  }
+
+  print_header("Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev");
+
+  /*           "NNNNNNNNNNNNNNNNNNNNNNNNN  NP  NR  SSSS FFFFFFFFFF SSSSSSSSSS  SSSSSSS  SSSSSS" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCESTATS);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCESTATS, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.sourcestats.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    format_name(name, sizeof (name), 25, ip_addr.family == IPADDR_UNSPEC,
+                ntohl(reply.data.sourcestats.ref_id), 1, &ip_addr);
+
+    print_report("%-25s %3U %3U  %I %+P %P  %+S  %S\n",
+                 name,
+                 ntohl(reply.data.sourcestats.n_samples),
+                 ntohl(reply.data.sourcestats.n_runs),
+                 ntohl(reply.data.sourcestats.span_seconds),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.resid_freq_ppm),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.skew_ppm),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.est_offset),
+                 UTI_FloatNetworkToHost(reply.data.sourcestats.sd),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_tracking(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t ref_id;
+  char name[256];
+  struct timespec ref_time;
+  
+  request.command = htons(REQ_TRACKING);
+  if (!request_reply(&request, &reply, RPY_TRACKING, 0))
+    return 0;
+
+  ref_id = ntohl(reply.data.tracking.ref_id);
+
+  UTI_IPNetworkToHost(&reply.data.tracking.ip_addr, &ip_addr);
+  format_name(name, sizeof (name), sizeof (name),
+              ip_addr.family == IPADDR_UNSPEC, ref_id, 1, &ip_addr);
+
+  UTI_TimespecNetworkToHost(&reply.data.tracking.ref_time, &ref_time);
+
+  print_report("Reference ID    : %R (%s)\n"
+               "Stratum         : %u\n"
+               "Ref time (UTC)  : %T\n"
+               "System time     : %.9O of NTP time\n"
+               "Last offset     : %+.9f seconds\n"
+               "RMS offset      : %.9f seconds\n"
+               "Frequency       : %.3F\n"
+               "Residual freq   : %+.3f ppm\n"
+               "Skew            : %.3f ppm\n"
+               "Root delay      : %.9f seconds\n"
+               "Root dispersion : %.9f seconds\n"
+               "Update interval : %.1f seconds\n"
+               "Leap status     : %L\n",
+               ref_id, name,
+               ntohs(reply.data.tracking.stratum),
+               &ref_time,
+               UTI_FloatNetworkToHost(reply.data.tracking.current_correction),
+               UTI_FloatNetworkToHost(reply.data.tracking.last_offset),
+               UTI_FloatNetworkToHost(reply.data.tracking.rms_offset),
+               UTI_FloatNetworkToHost(reply.data.tracking.freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.resid_freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.skew_ppm),
+               UTI_FloatNetworkToHost(reply.data.tracking.root_delay),
+               UTI_FloatNetworkToHost(reply.data.tracking.root_dispersion),
+               UTI_FloatNetworkToHost(reply.data.tracking.last_update_interval),
+               ntohs(reply.data.tracking.leap_status), REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_authdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t i, source_mode, n_sources;
+  int all, verbose;
+  const char *mode_str;
+  char name[256];
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf(    "                             .- Auth. mechanism (NTS, SK - symmetric key)\n");
+    printf(    "                            |   Key length -.  Cookie length (bytes) -.\n");
+    printf(    "                            |       (bits)  |  Num. of cookies --.    |\n");
+    printf(    "                            |               |  Key est. attempts  |   |\n");
+    printf(    "                            |               |           |         |   |\n");
+  }
+
+  print_header("Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen");
+
+  /*           "NNNNNNNNNNNNNNNNNNNNNNNNNNN MMMM KKKKK AAAA LLLL LLLL AAAA NNNN CCCC LLLL" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SOURCE_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+      return 0;
+
+    source_mode = ntohs(reply.data.source_data.mode);
+    if (source_mode != RPY_SD_MD_CLIENT && source_mode != RPY_SD_MD_PEER)
+      continue;
+
+    UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    request.command = htons(REQ_AUTH_DATA);
+    request.data.auth_data.ip_addr = reply.data.source_data.ip_addr;
+    if (!request_reply(&request, &reply, RPY_AUTH_DATA, 0))
+      return 0;
+
+    format_name(name, sizeof (name), 25, 0, 0, 1, &ip_addr);
+
+    switch (ntohs(reply.data.auth_data.mode)) {
+      case RPY_AD_MD_NONE:
+        mode_str = "-";
+        break;
+      case RPY_AD_MD_SYMMETRIC:
+        mode_str = "SK";
+        break;
+      case RPY_AD_MD_NTS:
+        mode_str = "NTS";
+        break;
+      default:
+        mode_str = "?";
+        break;
+    }
+
+    print_report("%-27s %4s %5U %4d %4d %I %4d %4d %4d %4d\n",
+                 name, mode_str,
+                 ntohl(reply.data.auth_data.key_id),
+                 ntohs(reply.data.auth_data.key_type),
+                 ntohs(reply.data.auth_data.key_length),
+                 ntohl(reply.data.auth_data.last_ke_ago),
+                 ntohs(reply.data.auth_data.ke_attempts),
+                 ntohs(reply.data.auth_data.nak),
+                 ntohs(reply.data.auth_data.cookies),
+                 ntohs(reply.data.auth_data.cookie_length),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_ntpdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr remote_addr, local_addr;
+  struct timespec ref_time;
+  uint32_t i, n_sources;
+  uint16_t mode;
+  int specified_addr;
+
+  if (*line) {
+    specified_addr = 1;
+    n_sources = 1;
+  } else {
+    specified_addr = 0;
+    request.command = htons(REQ_N_SOURCES);
+    if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+      return 0;
+    n_sources = ntohl(reply.data.n_sources.n_sources);
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    if (specified_addr) {
+      if (!parse_source_address(line, &remote_addr)) {
+        LOG(LOGS_ERR, "Could not get address for hostname");
+        return 0;
+      }
+    } else {
+      request.command = htons(REQ_SOURCE_DATA);
+      request.data.source_data.index = htonl(i);
+      if (!request_reply(&request, &reply, RPY_SOURCE_DATA, 0))
+        return 0;
+
+      mode = ntohs(reply.data.source_data.mode);
+      if (mode != RPY_SD_MD_CLIENT && mode != RPY_SD_MD_PEER)
+        continue;
+
+      UTI_IPNetworkToHost(&reply.data.source_data.ip_addr, &remote_addr);
+      if (!UTI_IsIPReal(&remote_addr))
+        continue;
+    }
+
+    request.command = htons(REQ_NTP_DATA);
+    UTI_IPHostToNetwork(&remote_addr, &request.data.ntp_data.ip_addr);
+    if (!request_reply(&request, &reply, RPY_NTP_DATA, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.ntp_data.remote_addr, &remote_addr);
+    UTI_IPNetworkToHost(&reply.data.ntp_data.local_addr, &local_addr);
+    UTI_TimespecNetworkToHost(&reply.data.ntp_data.ref_time, &ref_time);
+
+    if (!specified_addr && !csv_mode)
+      printf("\n");
+
+    print_report("Remote address  : %s (%R)\n"
+                 "Remote port     : %u\n"
+                 "Local address   : %s (%R)\n"
+                 "Leap status     : %L\n"
+                 "Version         : %u\n"
+                 "Mode            : %M\n"
+                 "Stratum         : %u\n"
+                 "Poll interval   : %d (%.0f seconds)\n"
+                 "Precision       : %d (%.9f seconds)\n"
+                 "Root delay      : %.6f seconds\n"
+                 "Root dispersion : %.6f seconds\n"
+                 "Reference ID    : %R (%s)\n"
+                 "Reference time  : %T\n"
+                 "Offset          : %+.9f seconds\n"
+                 "Peer delay      : %.9f seconds\n"
+                 "Peer dispersion : %.9f seconds\n"
+                 "Response time   : %.9f seconds\n"
+                 "Jitter asymmetry: %+.2f\n"
+                 "NTP tests       : %.3b %.3b %.4b\n"
+                 "Interleaved     : %B\n"
+                 "Authenticated   : %B\n"
+                 "TX timestamping : %N\n"
+                 "RX timestamping : %N\n"
+                 "Total TX        : %U\n"
+                 "Total RX        : %U\n"
+                 "Total valid RX  : %U\n"
+                 "Total good RX   : %U\n",
+                 UTI_IPToString(&remote_addr), UTI_IPToRefid(&remote_addr),
+                 ntohs(reply.data.ntp_data.remote_port),
+                 UTI_IPToString(&local_addr), UTI_IPToRefid(&local_addr),
+                 reply.data.ntp_data.leap, reply.data.ntp_data.version,
+                 reply.data.ntp_data.mode, reply.data.ntp_data.stratum,
+                 reply.data.ntp_data.poll, UTI_Log2ToDouble(reply.data.ntp_data.poll),
+                 reply.data.ntp_data.precision, UTI_Log2ToDouble(reply.data.ntp_data.precision),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.root_delay),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.root_dispersion),
+                 ntohl(reply.data.ntp_data.ref_id), reply.data.ntp_data.stratum <= 1 ?
+                   UTI_RefidToString(ntohl(reply.data.ntp_data.ref_id)) : "",
+                 &ref_time,
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.offset),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.peer_delay),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.peer_dispersion),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.response_time),
+                 UTI_FloatNetworkToHost(reply.data.ntp_data.jitter_asymmetry),
+                 ntohs(reply.data.ntp_data.flags) >> 7,
+                 ntohs(reply.data.ntp_data.flags) >> 4,
+                 ntohs(reply.data.ntp_data.flags),
+                 ntohs(reply.data.ntp_data.flags) & RPY_NTP_FLAG_INTERLEAVED,
+                 ntohs(reply.data.ntp_data.flags) & RPY_NTP_FLAG_AUTHENTICATED,
+                 reply.data.ntp_data.tx_tss_char, reply.data.ntp_data.rx_tss_char,
+                 ntohl(reply.data.ntp_data.total_tx_count),
+                 ntohl(reply.data.ntp_data.total_rx_count),
+                 ntohl(reply.data.ntp_data.total_valid_count),
+                 ntohl(reply.data.ntp_data.total_good_count),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_selectdata(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_sources;
+  int all, verbose, conf_options, eff_options;
+  char name[256];
+  IPAddr ip_addr;
+
+  parse_sources_options(line, &all, &verbose);
+
+  request.command = htons(REQ_N_SOURCES);
+  if (!request_reply(&request, &reply, RPY_N_SOURCES, 0))
+    return 0;
+
+  n_sources = ntohl(reply.data.n_sources.n_sources);
+
+  if (verbose) {
+    printf(    "  . State: N - noselect, s - unsynchronised, M - missing samples,\n");
+    printf(    " /         d/D - large distance, ~ - jittery, w/W - waits for others,\n");
+    printf(    "|          S - stale, O - orphan, T - not trusted, P - not preferred,\n");
+    printf(    "|          U - waits for update,, x - falseticker, + - combined, * - best.\n");
+    printf(    "|   Effective options   ---------.  (N - noselect, P - prefer\n");
+    printf(    "|   Configured options  ----.     \\  T - trust, R - require)\n");
+    printf(    "|   Auth. enabled (Y/N) -.   \\     \\     Offset interval --.\n");
+    printf(    "|                        |    |     |                       |\n");
+  }
+
+  print_header("S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap");
+
+  /*           "S NNNNNNNNNNNNNNNNNNNNNNNNN A OOOO- OOOO- LLLL SSSSS IIIIIII IIIIIII  L" */
+
+  for (i = 0; i < n_sources; i++) {
+    request.command = htons(REQ_SELECT_DATA);
+    request.data.source_data.index = htonl(i);
+    if (!request_reply(&request, &reply, RPY_SELECT_DATA, 0))
+      return 0;
+
+    UTI_IPNetworkToHost(&reply.data.select_data.ip_addr, &ip_addr);
+    if (!all && ip_addr.family == IPADDR_ID)
+      continue;
+
+    format_name(name, sizeof (name), 25, ip_addr.family == IPADDR_UNSPEC,
+                ntohl(reply.data.select_data.ref_id), 1, &ip_addr);
+
+    conf_options = ntohs(reply.data.select_data.conf_options);
+    eff_options = ntohs(reply.data.select_data.eff_options);
+
+    print_report("%c %-25s %c %c%c%c%c%c %c%c%c%c%c %I %5.1f %+S %+S  %1L\n",
+                 reply.data.select_data.state_char,
+                 name,
+                 reply.data.select_data.authentication ? 'Y' : 'N',
+                 conf_options & RPY_SD_OPTION_NOSELECT ? 'N' : '-',
+                 conf_options & RPY_SD_OPTION_PREFER ? 'P' : '-',
+                 conf_options & RPY_SD_OPTION_TRUST ? 'T' : '-',
+                 conf_options & RPY_SD_OPTION_REQUIRE ? 'R' : '-',
+                 '-',
+                 eff_options & RPY_SD_OPTION_NOSELECT ? 'N' : '-',
+                 eff_options & RPY_SD_OPTION_PREFER ? 'P' : '-',
+                 eff_options & RPY_SD_OPTION_TRUST ? 'T' : '-',
+                 eff_options & RPY_SD_OPTION_REQUIRE ? 'R' : '-',
+                 '-',
+                 ntohl(reply.data.select_data.last_sample_ago),
+                 UTI_FloatNetworkToHost(reply.data.select_data.score),
+                 UTI_FloatNetworkToHost(reply.data.select_data.lo_limit),
+                 UTI_FloatNetworkToHost(reply.data.select_data.hi_limit),
+                 reply.data.select_data.leap,
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_serverstats(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+
+  request.command = htons(REQ_SERVER_STATS);
+  if (!request_reply(&request, &reply, RPY_SERVER_STATS4, 0))
+    return 0;
+
+  print_report("NTP packets received       : %Q\n"
+               "NTP packets dropped        : %Q\n"
+               "Command packets received   : %Q\n"
+               "Command packets dropped    : %Q\n"
+               "Client log records dropped : %Q\n"
+               "NTS-KE connections accepted: %Q\n"
+               "NTS-KE connections dropped : %Q\n"
+               "Authenticated NTP packets  : %Q\n"
+               "Interleaved NTP packets    : %Q\n"
+               "NTP timestamps held        : %Q\n"
+               "NTP timestamp span         : %Q\n"
+               "NTP daemon RX timestamps   : %Q\n"
+               "NTP daemon TX timestamps   : %Q\n"
+               "NTP kernel RX timestamps   : %Q\n"
+               "NTP kernel TX timestamps   : %Q\n"
+               "NTP hardware RX timestamps : %Q\n"
+               "NTP hardware TX timestamps : %Q\n",
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_hits),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_drops),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.cmd_hits),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.cmd_drops),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.log_drops),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.nke_hits),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.nke_drops),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_auth_hits),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_interleaved_hits),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_span_seconds),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_daemon_rx_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_daemon_tx_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_kernel_rx_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_kernel_tx_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_hw_rx_timestamps),
+               UTI_Integer64NetworkToHost(reply.data.server_stats.ntp_hw_tx_timestamps),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_smoothing(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t flags;
+
+  request.command = htons(REQ_SMOOTHING);
+  if (!request_reply(&request, &reply, RPY_SMOOTHING, 0))
+    return 0;
+
+  flags = ntohl(reply.data.smoothing.flags);
+
+  print_report("Active         : %B %s\n"
+               "Offset         : %+.9f seconds\n"
+               "Frequency      : %+.6f ppm\n"
+               "Wander         : %+.6f ppm per second\n"
+               "Last update    : %.1f seconds ago\n"
+               "Remaining time : %.1f seconds\n",
+               !!(flags & RPY_SMT_FLAG_ACTIVE),
+               flags & RPY_SMT_FLAG_LEAPONLY ? "(leap second only)" : "",
+               UTI_FloatNetworkToHost(reply.data.smoothing.offset),
+               UTI_FloatNetworkToHost(reply.data.smoothing.freq_ppm),
+               UTI_FloatNetworkToHost(reply.data.smoothing.wander_ppm),
+               UTI_FloatNetworkToHost(reply.data.smoothing.last_update_ago),
+               UTI_FloatNetworkToHost(reply.data.smoothing.remaining_time),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_smoothtime(CMD_Request *msg, const char *line)
+{
+  if (!strcmp(line, "reset")) {
+    msg->data.smoothtime.option = htonl(REQ_SMOOTHTIME_RESET);
+  } else if (!strcmp(line, "activate")) {
+    msg->data.smoothtime.option = htonl(REQ_SMOOTHTIME_ACTIVATE);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for smoothtime command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_SMOOTHTIME);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_rtcreport(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  struct timespec ref_time;
+  
+  request.command = htons(REQ_RTCREPORT);
+  if (!request_reply(&request, &reply, RPY_RTC, 0))
+    return 0;
+
+  UTI_TimespecNetworkToHost(&reply.data.rtc.ref_time, &ref_time);
+
+  print_report("RTC ref time (UTC) : %T\n"
+               "Number of samples  : %u\n"
+               "Number of runs     : %u\n"
+               "Sample span period : %I\n"
+               "RTC is fast by     : %12.6f seconds\n"
+               "RTC gains time at  : %9.3f ppm\n",
+               &ref_time,
+               ntohs(reply.data.rtc.n_samples),
+               ntohs(reply.data.rtc.n_runs),
+               ntohl(reply.data.rtc.span_seconds),
+               UTI_FloatNetworkToHost(reply.data.rtc.rtc_seconds_fast),
+               UTI_FloatNetworkToHost(reply.data.rtc.rtc_gain_rate_ppm),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_clients(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip;
+  uint32_t i, n_clients, next_index, n_indices, min_hits, reset;
+  RPY_ClientAccesses_Client *client;
+  char header[80], name[50], *opt, *arg;
+  int nke;
+
+  next_index = 0;
+  min_hits = 0;
+  reset = 0;
+  nke = 0;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (strcmp(opt, "-k") == 0) {
+      nke = 1;
+    } else if (strcmp(opt, "-p") == 0) {
+      arg = line;
+      line = CPS_SplitWord(line);
+      if (sscanf(arg, "%"SCNu32, &min_hits) != 1) {
+        LOG(LOGS_ERR, "Invalid syntax for clients command");
+        return 0;
+      }
+    } else if (strcmp(opt, "-r") == 0) {
+      reset = 1;
+    }
+  }
+
+  snprintf(header, sizeof (header),
+           "Hostname                      NTP   Drop Int IntL Last  %6s   Drop Int  Last",
+           nke ? "NTS-KE" : "Cmd");
+  print_header(header);
+
+  while (1) {
+    request.command = htons(REQ_CLIENT_ACCESSES_BY_INDEX3);
+    request.data.client_accesses_by_index.first_index = htonl(next_index);
+    request.data.client_accesses_by_index.n_clients = htonl(MAX_CLIENT_ACCESSES);
+    request.data.client_accesses_by_index.min_hits = htonl(min_hits);
+    request.data.client_accesses_by_index.reset = htonl(reset);
+
+    if (!request_reply(&request, &reply, RPY_CLIENT_ACCESSES_BY_INDEX3, 0))
+      return 0;
+
+    n_clients = ntohl(reply.data.client_accesses_by_index.n_clients);
+    n_indices = ntohl(reply.data.client_accesses_by_index.n_indices);
+
+    for (i = 0; i < n_clients && i < MAX_CLIENT_ACCESSES; i++) {
+      client = &reply.data.client_accesses_by_index.clients[i];
+
+      UTI_IPNetworkToHost(&client->ip, &ip);
+
+      /* UNSPEC means the record could not be found in the daemon's tables.
+         We shouldn't ever generate this case, but ignore it if we do. */
+      if (ip.family == IPADDR_UNSPEC)
+        continue;
+
+      format_name(name, sizeof (name), 25, 0, 0, 0, &ip);
+
+      print_report("%-25s  %6U  %5U  %C  %C  %I  %6U  %5U  %C  %I\n",
+                   name,
+                   ntohl(client->ntp_hits),
+                   ntohl(client->ntp_drops),
+                   client->ntp_interval,
+                   client->ntp_timeout_interval,
+                   ntohl(client->last_ntp_hit_ago),
+                   ntohl(nke ? client->nke_hits : client->cmd_hits),
+                   ntohl(nke ? client->nke_drops : client->cmd_drops),
+                   nke ? client->nke_interval : client->cmd_interval,
+                   ntohl(nke ? client->last_nke_hit_ago : client->last_cmd_hit_ago),
+                   REPORT_END);
+    }
+
+    /* Set the next index to probe based on what the server tells us */
+    next_index = ntohl(reply.data.client_accesses_by_index.next_index);
+
+    if (next_index >= n_indices || n_clients < MAX_CLIENT_ACCESSES)
+      break;
+  }
+
+  return 1;
+}
+
+
+/* ================================================== */
+/* Process the manual list command */
+static int
+process_cmd_manual_list(const char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  uint32_t i, n_samples;
+  RPY_ManualListSample *sample;
+  struct timespec when;
+
+  request.command = htons(REQ_MANUAL_LIST);
+  if (!request_reply(&request, &reply, RPY_MANUAL_LIST2, 0))
+    return 0;
+
+  n_samples = ntohl(reply.data.manual_list.n_samples);
+  print_info_field("210 n_samples = %"PRIu32"\n", n_samples);
+
+  print_header("#    Date     Time(UTC)    Slewed   Original   Residual");
+
+  for (i = 0; i < n_samples && i < MAX_MANUAL_LIST_SAMPLES; i++) {
+    sample = &reply.data.manual_list.samples[i];
+    UTI_TimespecNetworkToHost(&sample->when, &when);
+
+    print_report("%2d %s %10.2f %10.2f %10.2f\n",
+                 i, UTI_TimeToLogForm(when.tv_sec),
+                 UTI_FloatNetworkToHost(sample->slewed_offset),
+                 UTI_FloatNetworkToHost(sample->orig_offset),
+                 UTI_FloatNetworkToHost(sample->residual),
+                 REPORT_END);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_manual_delete(CMD_Request *msg, const char *line)
+{
+  int index;
+
+  if (sscanf(line, "%d", &index) != 1) {
+    LOG(LOGS_ERR, "Bad syntax for manual delete command");
+    return 0;
+  }
+
+  msg->command = htons(REQ_MANUAL_DELETE);
+  msg->data.manual_delete.index = htonl(index);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_settime(char *line)
+{
+  struct timespec ts;
+  time_t now, new_time;
+  CMD_Request request;
+  CMD_Reply reply;
+  double dfreq_ppm, new_afreq_ppm;
+  double offset;
+
+  now = time(NULL);
+  new_time = get_date(line, &now);
+
+  if (new_time == -1) {
+    printf("510 - Could not parse date string\n");
+  } else {
+    ts.tv_sec = new_time;
+    ts.tv_nsec = 0;
+    UTI_TimespecHostToNetwork(&ts, &request.data.settime.ts);
+    request.command = htons(REQ_SETTIME);
+    if (request_reply(&request, &reply, RPY_MANUAL_TIMESTAMP2, 1)) {
+          offset = UTI_FloatNetworkToHost(reply.data.manual_timestamp.offset);
+          dfreq_ppm = UTI_FloatNetworkToHost(reply.data.manual_timestamp.dfreq_ppm);
+          new_afreq_ppm = UTI_FloatNetworkToHost(reply.data.manual_timestamp.new_afreq_ppm);
+          printf("Clock was %.2f seconds fast.  Frequency change = %.2fppm, new frequency = %.2fppm\n",
+              offset, dfreq_ppm, new_afreq_ppm);
+          return 1;
+    }
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+process_cmd_rekey(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_REKEY);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_makestep(CMD_Request *msg, char *line)
+{
+  int limit;
+  double threshold;
+
+  if (*line) {
+    if (sscanf(line, "%lf %d", &threshold, &limit) != 2) {
+      LOG(LOGS_ERR, "Bad syntax for makestep command");
+      return 0;
+    }
+    msg->command = htons(REQ_MODIFY_MAKESTEP);
+    msg->data.modify_makestep.limit = htonl(limit);
+    msg->data.modify_makestep.threshold = UTI_FloatHostToNetwork(threshold);
+  } else {
+    msg->command = htons(REQ_MAKESTEP);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_activity(const char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+
+  request.command = htons(REQ_ACTIVITY);
+  if (!request_reply(&request, &reply, RPY_ACTIVITY, 0))
+    return 0;
+
+  print_info_field("200 OK\n");
+
+  print_report("%U sources online\n"
+               "%U sources offline\n"
+               "%U sources doing burst (return to online)\n"
+               "%U sources doing burst (return to offline)\n"
+               "%U sources with unknown address\n",
+               ntohl(reply.data.activity.online),
+               ntohl(reply.data.activity.offline),
+               ntohl(reply.data.activity.burst_online),
+               ntohl(reply.data.activity.burst_offline),
+               ntohl(reply.data.activity.unresolved),
+               REPORT_END);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reselectdist(CMD_Request *msg, char *line)
+{
+  double dist;
+  int ok;
+  msg->command = htons(REQ_RESELECTDISTANCE);
+  if (sscanf(line, "%lf", &dist) == 1) {
+    msg->data.reselect_distance.distance = UTI_FloatHostToNetwork(dist);
+    ok = 1;
+  } else {
+    ok = 0;
+  }
+  return ok;
+}
+
+/* ================================================== */
+
+static void
+process_cmd_reselect(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_RESELECT);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_refresh(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_REFRESH);
+}
+
+/* ================================================== */
+
+static void
+process_cmd_shutdown(CMD_Request *msg, char *line)
+{
+  msg->command = htons(REQ_SHUTDOWN);
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reload(CMD_Request *msg, char *line)
+{
+  if (!strcmp(line, "sources")) {
+    msg->command = htons(REQ_RELOAD_SOURCES);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for reload command");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_reset(CMD_Request *msg, char *line)
+{
+  if (!strcmp(line, "sources")) {
+    msg->command = htons(REQ_RESET_SOURCES);
+  } else {
+    LOG(LOGS_ERR, "Invalid syntax for reset command");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_selectopts(CMD_Request *msg, char *line)
+{
+  int mask, options, option;
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  char *src, *opt;
+
+  src = line;
+  line = CPS_SplitWord(line);
+  ref_id = 0;
+
+  /* Don't allow hostnames to avoid conflicts with reference IDs */
+  if (!UTI_StringToIdIP(src, &ip_addr) && !UTI_StringToIP(src, &ip_addr)) {
+    ip_addr.family = IPADDR_UNSPEC;
+    if (CPS_ParseRefid(src, &ref_id) == 0) {
+      LOG(LOGS_ERR, "Invalid syntax for selectopts command");
+      return 0;
+    }
+  }
+
+  mask = options = 0;
+
+  while (*line != '\0') {
+    opt = line;
+    line = CPS_SplitWord(line);
+
+    if ((opt[0] != '+' && opt[0] != '-') || (option = CPS_GetSelectOption(opt + 1)) == 0) {
+      LOG(LOGS_ERR, "Invalid syntax for selectopts command");
+      return 0;
+    }
+
+    mask |= option;
+    if (opt[0] == '+')
+      options |= option;
+  }
+
+  UTI_IPHostToNetwork(&ip_addr, &msg->data.modify_select_opts.address);
+  msg->data.modify_select_opts.ref_id = htonl(ref_id);
+  msg->data.modify_select_opts.mask = htonl(mask);
+  msg->data.modify_select_opts.options = htonl(convert_addsrc_sel_options(options));
+
+  msg->command = htons(REQ_MODIFY_SELECTOPTS);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_waitsync(char *line)
+{
+  CMD_Request request;
+  CMD_Reply reply;
+  IPAddr ip_addr;
+  uint32_t ref_id;
+  double correction, skew_ppm, max_correction, max_skew_ppm, interval;
+  int ret = 0, max_tries, i;
+  struct timeval timeout;
+
+  max_tries = 0;
+  max_correction = 0.0;
+  max_skew_ppm = 0.0;
+  interval = 10.0;
+
+  if (sscanf(line, "%d %lf %lf %lf", &max_tries, &max_correction, &max_skew_ppm, &interval))
+    ;
+
+  /* Don't allow shorter interval than 0.1 seconds */
+  if (interval < 0.1)
+    interval = 0.1;
+
+  request.command = htons(REQ_TRACKING);
+
+  for (i = 1; ; i++) {
+    if (request_reply(&request, &reply, RPY_TRACKING, 0)) {
+      ref_id = ntohl(reply.data.tracking.ref_id);
+      UTI_IPNetworkToHost(&reply.data.tracking.ip_addr, &ip_addr);
+
+      correction = UTI_FloatNetworkToHost(reply.data.tracking.current_correction);
+      correction = fabs(correction);
+      skew_ppm = UTI_FloatNetworkToHost(reply.data.tracking.skew_ppm);
+
+      print_report("try: %d, refid: %R, correction: %.9f, skew: %.3f\n",
+                   i, ref_id, correction, skew_ppm, REPORT_END);
+
+      if ((ip_addr.family != IPADDR_UNSPEC ||
+           (ref_id != 0 && ref_id != 0x7f7f0101L /* LOCAL refid */)) &&
+          (max_correction == 0.0 || correction <= max_correction) &&
+          (max_skew_ppm == 0.0 || skew_ppm <= max_skew_ppm)) {
+        ret = 1;
+      }
+    }
+
+    if (!ret && (!max_tries || i < max_tries) && !quit) {
+      UTI_DoubleToTimeval(interval, &timeout);
+      if (select(0, NULL, NULL, NULL, &timeout))
+        break;
+    } else {
+      break;
+    }
+  }
+  return ret;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_dns(const char *line)
+{
+  if (!strcmp(line, "-46")) {
+    DNS_SetAddressFamily(IPADDR_UNSPEC);
+  } else if (!strcmp(line, "-4")) {
+    DNS_SetAddressFamily(IPADDR_INET4);
+  } else if (!strcmp(line, "-6")) {
+    DNS_SetAddressFamily(IPADDR_INET6);
+  } else if (!strcmp(line, "-n")) {
+    no_dns = 1;
+  } else if (!strcmp(line, "+n")) {
+    no_dns = 0;
+  } else {
+    LOG(LOGS_ERR, "Unrecognized dns command");
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_timeout(const char *line)
+{
+  int timeout;
+
+  timeout = atoi(line);
+  if (timeout < 100) {
+    LOG(LOGS_ERR, "Timeout %d is too short", timeout);
+    return 0;
+  }
+  initial_timeout = timeout;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_retries(const char *line)
+{
+  int retries;
+
+  retries = atoi(line);
+  if (retries < 0 || retries > 30) {
+    LOG(LOGS_ERR, "Invalid maximum number of retries");
+    return 0;
+  }
+  max_retries = retries;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_cmd_keygen(char *line)
+{
+  unsigned int i, args, cmac_length, length, id = 1, bits = 160;
+  unsigned char key[512];
+  const char *type;
+  char *words[3];
+
+#ifdef FEAT_SECHASH
+  type = "SHA1";
+#else
+  type = "MD5";
+#endif
+
+  args = UTI_SplitString(line, words, 3);
+  if (args >= 2)
+    type = words[1];
+
+  if (args > 3 ||
+      (args >= 1 && sscanf(words[0], "%u", &id) != 1) ||
+      (args >= 3 && sscanf(words[2], "%u", &bits) != 1)) {
+    LOG(LOGS_ERR, "Invalid syntax for keygen command");
+    return 0;
+  }
+
+#ifdef HAVE_CMAC
+  cmac_length = CMC_GetKeyLength(UTI_CmacNameToAlgorithm(type));
+#else
+  cmac_length = 0;
+#endif
+
+  if (HSH_GetHashId(UTI_HashNameToAlgorithm(type)) >= 0) {
+    length = (bits + 7) / 8;
+  } else if (cmac_length > 0) {
+    length = cmac_length;
+  } else {
+    LOG(LOGS_ERR, "Unknown hash function or cipher %s", type);
+    return 0;
+  }
+
+  length = CLAMP(10, length, sizeof (key));
+
+  UTI_GetRandomBytesUrandom(key, length);
+
+  printf("%u %s HEX:", id, type);
+  for (i = 0; i < length; i++)
+    printf("%02hhX", key[i]);
+  printf("\n");
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_line(char *line)
+{
+  char *command;
+  int do_normal_submit;
+  int ret;
+  CMD_Request tx_message;
+  CMD_Reply rx_message;
+
+  ret = 0;
+
+  do_normal_submit = 1;
+
+  CPS_NormalizeLine(line);
+
+  if (!*line) {
+    fflush(stderr);
+    fflush(stdout);
+    return 1;
+  };
+
+  command = line;
+  line = CPS_SplitWord(line);
+
+  if (!strcmp(command, "accheck")) {
+    do_normal_submit = process_cmd_accheck(&tx_message, line);
+  } else if (!strcmp(command, "activity")) {
+    do_normal_submit = 0;
+    ret = process_cmd_activity(line);
+  } else if (!strcmp(command, "add")) {
+    do_normal_submit = process_cmd_add_source(&tx_message, line);
+  } else if (!strcmp(command, "allow")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_ALLOW, REQ_ALLOWALL);
+  } else if (!strcmp(command, "authdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_authdata(line);
+  } else if (!strcmp(command, "burst")) {
+    do_normal_submit = process_cmd_burst(&tx_message, line);
+  } else if (!strcmp(command, "clients")) {
+    ret = process_cmd_clients(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "cmdaccheck")) {
+    do_normal_submit = process_cmd_cmdaccheck(&tx_message, line);
+  } else if (!strcmp(command, "cmdallow")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_CMDALLOW, REQ_CMDALLOWALL);
+  } else if (!strcmp(command, "cmddeny")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_CMDDENY, REQ_CMDDENYALL);
+  } else if (!strcmp(command, "cyclelogs")) {
+    process_cmd_cyclelogs(&tx_message, line);
+  } else if (!strcmp(command, "delete")) {
+    do_normal_submit = process_cmd_delete(&tx_message, line);
+  } else if (!strcmp(command, "deny")) {
+    do_normal_submit = process_cmd_allowdeny(&tx_message, line, REQ_DENY, REQ_DENYALL);
+  } else if (!strcmp(command, "dfreq")) {
+    do_normal_submit = process_cmd_dfreq(&tx_message, line);
+  } else if (!strcmp(command, "dns")) {
+    ret = process_cmd_dns(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "doffset")) {
+    do_normal_submit = process_cmd_doffset(&tx_message, line);
+  } else if (!strcmp(command, "dump")) {
+    process_cmd_dump(&tx_message, line);
+  } else if (!strcmp(command, "exit")) {
+    do_normal_submit = 0;
+    quit = 1;
+    ret = 1;
+  } else if (!strcmp(command, "help")) {
+    do_normal_submit = 0;
+    give_help();
+    ret = 1;
+  } else if (!strcmp(command, "keygen")) {
+    ret = process_cmd_keygen(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "local")) {
+    do_normal_submit = process_cmd_local(&tx_message, line);
+  } else if (!strcmp(command, "makestep")) {
+    do_normal_submit = process_cmd_makestep(&tx_message, line);
+  } else if (!strcmp(command, "manual")) {
+    if (!strncmp(line, "list", 4)) {
+      do_normal_submit = 0;
+      ret = process_cmd_manual_list(CPS_SplitWord(line));
+    } else if (!strncmp(line, "delete", 6)) {
+      do_normal_submit = process_cmd_manual_delete(&tx_message, CPS_SplitWord(line));
+    } else {
+      do_normal_submit = process_cmd_manual(&tx_message, line);
+    }
+  } else if (!strcmp(command, "maxdelay")) {
+    do_normal_submit = process_cmd_maxdelay(&tx_message, line);
+  } else if (!strcmp(command, "maxdelaydevratio")) {
+    do_normal_submit = process_cmd_maxdelaydevratio(&tx_message, line);
+  } else if (!strcmp(command, "maxdelayratio")) {
+    do_normal_submit = process_cmd_maxdelayratio(&tx_message, line);
+  } else if (!strcmp(command, "maxpoll")) {
+    do_normal_submit = process_cmd_maxpoll(&tx_message, line);
+  } else if (!strcmp(command, "maxupdateskew")) {
+    do_normal_submit = process_cmd_maxupdateskew(&tx_message, line);
+  } else if (!strcmp(command, "minpoll")) {
+    do_normal_submit = process_cmd_minpoll(&tx_message, line);
+  } else if (!strcmp(command, "minstratum")) {
+    do_normal_submit = process_cmd_minstratum(&tx_message, line);
+  } else if (!strcmp(command, "ntpdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_ntpdata(line);
+  } else if (!strcmp(command, "offline")) {
+    do_normal_submit = process_cmd_offline(&tx_message, line);
+  } else if (!strcmp(command, "online")) {
+    do_normal_submit = process_cmd_online(&tx_message, line);
+  } else if (!strcmp(command, "onoffline")) {
+    process_cmd_onoffline(&tx_message, line);
+  } else if (!strcmp(command, "polltarget")) {
+    do_normal_submit = process_cmd_polltarget(&tx_message, line);
+  } else if (!strcmp(command, "quit")) {
+    do_normal_submit = 0;
+    quit = 1;
+    ret = 1;
+  } else if (!strcmp(command, "refresh")) {
+    process_cmd_refresh(&tx_message, line);
+  } else if (!strcmp(command, "rekey")) {
+    process_cmd_rekey(&tx_message, line);
+  } else if (!strcmp(command, "reload")) {
+    do_normal_submit = process_cmd_reload(&tx_message, line);
+  } else if (!strcmp(command, "reselect")) {
+    process_cmd_reselect(&tx_message, line);
+  } else if (!strcmp(command, "reselectdist")) {
+    do_normal_submit = process_cmd_reselectdist(&tx_message, line);
+  } else if (!strcmp(command, "reset")) {
+    do_normal_submit = process_cmd_reset(&tx_message, line);
+  } else if (!strcmp(command, "retries")) {
+    ret = process_cmd_retries(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "rtcdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_rtcreport(line);
+  } else if (!strcmp(command, "selectdata")) {
+    do_normal_submit = 0;
+    ret = process_cmd_selectdata(line);
+  } else if (!strcmp(command, "selectopts")) {
+    do_normal_submit = process_cmd_selectopts(&tx_message, line);
+  } else if (!strcmp(command, "serverstats")) {
+    do_normal_submit = 0;
+    ret = process_cmd_serverstats(line);
+  } else if (!strcmp(command, "settime")) {
+    do_normal_submit = 0;
+    ret = process_cmd_settime(line);
+  } else if (!strcmp(command, "shutdown")) {
+    process_cmd_shutdown(&tx_message, line);
+  } else if (!strcmp(command, "smoothing")) {
+    do_normal_submit = 0;
+    ret = process_cmd_smoothing(line);
+  } else if (!strcmp(command, "smoothtime")) {
+    do_normal_submit = process_cmd_smoothtime(&tx_message, line);
+  } else if (!strcmp(command, "sourcename")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sourcename(line);
+  } else if (!strcmp(command, "sources")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sources(line);
+  } else if (!strcmp(command, "sourcestats")) {
+    do_normal_submit = 0;
+    ret = process_cmd_sourcestats(line);
+  } else if (!strcmp(command, "timeout")) {
+    ret = process_cmd_timeout(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "tracking")) {
+    ret = process_cmd_tracking(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "trimrtc")) {
+    process_cmd_trimrtc(&tx_message, line);
+  } else if (!strcmp(command, "waitsync")) {
+    ret = process_cmd_waitsync(line);
+    do_normal_submit = 0;
+  } else if (!strcmp(command, "writertc")) {
+    process_cmd_writertc(&tx_message, line);
+  } else if (!strcmp(command, "authhash") ||
+             !strcmp(command, "password")) {
+    /* Warn, but don't return error to not break scripts */
+    LOG(LOGS_WARN, "Authentication is no longer supported");
+    do_normal_submit = 0;
+    ret = 1;
+  } else {
+    LOG(LOGS_ERR, "Unrecognized command");
+    do_normal_submit = 0;
+  }
+    
+  if (do_normal_submit) {
+    ret = request_reply(&tx_message, &rx_message, RPY_NULL, 1);
+  }
+
+  if (end_dot) {
+    printf(".\n");
+  }
+
+  fflush(stderr);
+
+  if (fflush(stdout) != 0 || ferror(stdout) != 0) {
+    LOG(LOGS_ERR, "Could not write to stdout");
+
+    /* Return error for commands that print data */
+    if (!do_normal_submit)
+      return 0;
+  }
+
+  return ret;
+}
+
+/* ================================================== */
+
+#define MAX_LINE_LENGTH 2048
+
+static int
+process_args(int argc, char **argv, int multi)
+{
+  char line[MAX_LINE_LENGTH];
+  int i, l, ret = 0;
+
+  for (i = l = 0; i < argc; i++) {
+    l += snprintf(line + l, sizeof (line) - l, "%s ", argv[i]);
+    if (l >= sizeof (line)) {
+      LOG(LOGS_ERR, "Command too long");
+      return 0;
+    }
+
+    if (!multi && i + 1 < argc)
+      continue;
+
+    ret = process_line(line);
+    if (!ret || quit)
+      break;
+
+    l = 0;
+  }
+
+  return ret;
+}
+
+/* ================================================== */
+
+static void
+signal_handler(int signum)
+{
+  quit = 1;
+}
+
+/* ================================================== */
+
+static void
+display_gpl(void)
+{
+    printf("chrony version %s\n"
+           "Copyright (C) 1997-2003, 2007, 2009-2023 Richard P. Curnow and others\n"
+           "chrony comes with ABSOLUTELY NO WARRANTY.  This is free software, and\n"
+           "you are welcome to redistribute it under certain conditions.  See the\n"
+           "GNU General Public License version 2 for details.\n\n",
+           CHRONY_VERSION);
+}
+
+/* ================================================== */
+
+static void
+print_help(const char *progname)
+{
+      printf("Usage: %s [OPTION]... [COMMAND]...\n\n"
+             "Options:\n"
+             "  -4\t\tUse IPv4 addresses only\n"
+             "  -6\t\tUse IPv6 addresses only\n"
+             "  -n\t\tDon't resolve hostnames\n"
+             "  -N\t\tPrint original source names\n"
+             "  -c\t\tEnable CSV format\n"
+             "  -e\t\tEnd responses with dot\n"
+#if DEBUG > 0
+             "  -d\t\tEnable debug messages\n"
+#endif
+             "  -m\t\tAccept multiple commands\n"
+             "  -h HOST\tSpecify server (%s)\n"
+             "  -p PORT\tSpecify UDP port (%d)\n"
+             "  -v, --version\tPrint version and exit\n"
+             "      --help\tPrint usage and exit\n",
+             progname, DEFAULT_COMMAND_SOCKET",127.0.0.1,::1", DEFAULT_CANDM_PORT);
+}
+
+/* ================================================== */
+
+static void
+print_version(void)
+{
+      printf("chronyc (chrony) version %s (%s)\n", CHRONY_VERSION, CHRONYC_FEATURES);
+}
+
+/* ================================================== */
+
+int
+main(int argc, char **argv)
+{
+  char *line;
+  const char *progname = argv[0];
+  const char *hostnames = NULL;
+  int opt, ret = 1, multi = 0, family = IPADDR_UNSPEC;
+  int port = DEFAULT_CANDM_PORT;
+
+  /* Parse long command-line options */
+  for (optind = 1; optind < argc; optind++) {
+    if (!strcmp("--help", argv[optind])) {
+      print_help(progname);
+      return 0;
+    } else if (!strcmp("--version", argv[optind])) {
+      print_version();
+      return 0;
+    }
+  }
+
+  optind = 1;
+
+  /* Parse short command-line options */
+  while ((opt = getopt(argc, argv, "+46acdef:h:mnNp:v")) != -1) {
+    switch (opt) {
+      case '4':
+      case '6':
+        family = opt == '4' ? IPADDR_INET4 : IPADDR_INET6;
+        break;
+      case 'a':
+      case 'f':
+        /* For compatibility only */
+        break;
+      case 'c':
+        csv_mode = 1;
+        break;
+      case 'd':
+#if DEBUG > 0
+        log_min_severity = LOGS_DEBUG;
+#endif
+        break;
+      case 'e':
+        end_dot = 1;
+        break;
+      case 'h':
+        hostnames = optarg;
+        break;
+      case 'm':
+        multi = 1;
+        break;
+      case 'n':
+        no_dns = 1;
+        break;
+      case 'N':
+        source_names = 1;
+        break;
+      case 'p':
+        port = atoi(optarg);
+        break;
+      case 'v':
+        print_version();
+        return 0;
+      default:
+        print_help(progname);
+        return 1;
+    }
+  }
+
+  if (isatty(0) && isatty(1) && isatty(2)) {
+    on_terminal = 1;
+  }
+
+  if (on_terminal && optind == argc) {
+    display_gpl();
+  }
+  
+  DNS_SetAddressFamily(family);
+
+  if (!hostnames) {
+    hostnames = DEFAULT_COMMAND_SOCKET",127.0.0.1,::1";
+  }
+
+  UTI_SetQuitSignalsHandler(signal_handler, 0);
+
+  SCK_Initialise(IPADDR_UNSPEC);
+  server_addresses = get_addresses(hostnames, port);
+
+  if (!open_io())
+    LOG_FATAL("Could not open connection to daemon");
+
+  if (optind < argc) {
+    ret = process_args(argc - optind, argv + optind, multi);
+  } else {
+    do {
+      line = read_line();
+      if (line && !quit) {
+        ret = process_line(line);
+      }else {
+	/* supply the final '\n' when user exits via ^D */
+        if( on_terminal ) printf("\n");
+      }
+    } while (line && !quit);
+  }
+
+  close_io();
+  free_addresses(server_addresses);
+  SCK_Finalise();
+
+  return !ret;
+}
+
+
diff --git a/clientlog.c b/clientlog.c
new file mode 100644
index 0000000..c408e8d
--- /dev/null
+++ b/clientlog.c
@@ -0,0 +1,1111 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009, 2015-2017, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module keeps a count of the number of successful accesses by
+  clients, and the times of the last accesses.
+
+  This can be used for status reporting, and (in the case of a
+  server), if it needs to know which clients have made use of its data
+  recently.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "clientlog.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "ntp.h"
+#include "reports.h"
+#include "util.h"
+#include "logging.h"
+
+#define MAX_SERVICES 3
+
+typedef struct {
+  IPAddr ip_addr;
+  uint32_t last_hit[MAX_SERVICES];
+  uint32_t hits[MAX_SERVICES];
+  uint16_t drops[MAX_SERVICES];
+  uint16_t tokens[MAX_SERVICES];
+  int8_t rate[MAX_SERVICES];
+  int8_t ntp_timeout_rate;
+  uint8_t drop_flags;
+} Record;
+
+/* Hash table of records, there is a fixed number of records per slot */
+static ARR_Instance records;
+
+#define SLOT_BITS 4
+
+/* Number of records in one slot of the hash table */
+#define SLOT_SIZE (1U << SLOT_BITS)
+
+/* Minimum number of slots */
+#define MIN_SLOTS 1
+
+/* Maximum number of slots, this is a hard limit */
+#define MAX_SLOTS (1U << (24 - SLOT_BITS))
+
+/* Number of slots in the hash table */
+static unsigned int slots;
+
+/* Maximum number of slots given memory allocation limit */
+static unsigned int max_slots;
+
+/* Times of last hits are saved as 32-bit fixed point values */
+#define TS_FRAC 4
+#define INVALID_TS 0
+
+/* Static offset included in conversion to the fixed-point timestamps to
+   randomise their alignment */
+static uint32_t ts_offset;
+
+/* Request rates are saved in the record as 8-bit scaled log2 values */
+#define RATE_SCALE 4
+#define MIN_RATE (-14 * RATE_SCALE)
+#define INVALID_RATE -128
+
+/* Response rates are controlled by token buckets.  The capacity and
+   number of tokens spent on response are determined from configured
+   minimum inverval between responses (in log2) and burst length. */
+
+#define MIN_LIMIT_INTERVAL (-15 - TS_FRAC)
+#define MAX_LIMIT_INTERVAL 12
+#define MIN_LIMIT_BURST 1
+#define MAX_LIMIT_BURST 255
+
+static uint16_t max_tokens[MAX_SERVICES];
+static uint16_t tokens_per_hit[MAX_SERVICES];
+
+/* Reduction of token rates to avoid overflow of 16-bit counters.  Negative
+   shift is used for coarse limiting with intervals shorter than -TS_FRAC. */
+static int token_shift[MAX_SERVICES];
+
+/* Rates at which responses are randomly allowed (in log2) when the
+   buckets don't have enough tokens.  This is necessary in order to
+   prevent an attacker sending requests with spoofed source address
+   from blocking responses to the address completely. */
+
+#define MIN_LEAK_RATE 1
+#define MAX_LEAK_RATE 4
+
+static int leak_rate[MAX_SERVICES];
+
+/* Limit intervals in log2 */
+static int limit_interval[MAX_SERVICES];
+
+/* Flag indicating whether facility is turned on or not */
+static int active;
+
+/* RX and TX timestamp saved for clients using interleaved mode */
+typedef struct {
+  uint64_t rx_ts;
+  uint8_t flags;
+  uint8_t tx_ts_source;
+  uint16_t slew_epoch;
+  int32_t tx_ts_offset;
+} NtpTimestamps;
+
+/* Flags for NTP timestamps */
+#define NTPTS_DISABLED 1
+#define NTPTS_VALID_TX 2
+
+/* RX->TX map using a circular buffer with ordered timestamps */
+typedef struct {
+  ARR_Instance timestamps;
+  uint32_t first;
+  uint32_t size;
+  uint32_t max_size;
+  uint32_t cached_index;
+  uint64_t cached_rx_ts;
+  uint16_t slew_epoch;
+  double slew_offset;
+} NtpTimestampMap;
+
+static NtpTimestampMap ntp_ts_map;
+
+/* Maximum interval of NTP timestamps in future after a backward step */
+#define NTPTS_FUTURE_LIMIT (1LL << 32) /* 1 second */
+
+/* Maximum number of timestamps moved in the array to insert a new timestamp */
+#define NTPTS_INSERT_LIMIT 64
+
+/* Maximum expected value of the timestamp source */
+#define MAX_NTP_TS NTP_TS_HARDWARE
+
+/* Global statistics */
+static uint64_t total_hits[MAX_SERVICES];
+static uint64_t total_drops[MAX_SERVICES];
+static uint64_t total_ntp_auth_hits;
+static uint64_t total_ntp_interleaved_hits;
+static uint64_t total_record_drops;
+static uint64_t total_ntp_rx_timestamps[MAX_NTP_TS + 1];
+static uint64_t total_ntp_tx_timestamps[MAX_NTP_TS + 1];
+
+#define NSEC_PER_SEC 1000000000U
+
+/* ================================================== */
+
+static int expand_hashtable(void);
+static void handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+                        double doffset, LCL_ChangeType change_type, void *anything);
+
+/* ================================================== */
+
+static int
+compare_ts(uint32_t x, uint32_t y)
+{
+  if (x == y)
+    return 0;
+  if (y == INVALID_TS)
+    return 1;
+  return (int32_t)(x - y) > 0 ? 1 : -1;
+}
+
+/* ================================================== */
+
+static int
+compare_total_hits(Record *x, Record *y)
+{
+  uint32_t x_hits, y_hits;
+  int i;
+
+  for (i = 0, x_hits = y_hits = 0; i < MAX_SERVICES; i++) {
+    x_hits += x->hits[i];
+    y_hits += y->hits[i];
+  }
+
+  return x_hits > y_hits ? 1 : -1;
+}
+
+/* ================================================== */
+
+static Record *
+get_record(IPAddr *ip)
+{
+  uint32_t last_hit = 0, oldest_hit = 0;
+  Record *record, *oldest_record;
+  unsigned int first, i, j;
+
+  if (!active || (ip->family != IPADDR_INET4 && ip->family != IPADDR_INET6))
+    return NULL;
+
+  while (1) {
+    /* Get index of the first record in the slot */
+    first = UTI_IPToHash(ip) % slots * SLOT_SIZE;
+
+    for (i = 0, oldest_record = NULL; i < SLOT_SIZE; i++) {
+      record = ARR_GetElement(records, first + i);
+
+      if (!UTI_CompareIPs(ip, &record->ip_addr, NULL))
+        return record;
+
+      if (record->ip_addr.family == IPADDR_UNSPEC)
+        break;
+
+      for (j = 0; j < MAX_SERVICES; j++) {
+        if (j == 0 || compare_ts(last_hit, record->last_hit[j]) < 0)
+          last_hit = record->last_hit[j];
+      }
+
+      if (!oldest_record || compare_ts(oldest_hit, last_hit) > 0 ||
+          (oldest_hit == last_hit && compare_total_hits(oldest_record, record) > 0)) {
+        oldest_record = record;
+        oldest_hit = last_hit;
+      }
+    }
+
+    /* If the slot still has an empty record, use it */
+    if (record->ip_addr.family == IPADDR_UNSPEC)
+      break;
+
+    /* Resize the table if possible and try again as the new slot may
+       have some empty records */
+    if (expand_hashtable())
+      continue;
+
+    /* There is no other option, replace the oldest record */
+    record = oldest_record;
+    total_record_drops++;
+    break;
+  }
+
+  record->ip_addr = *ip;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->last_hit[i] = INVALID_TS;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->hits[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->drops[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->tokens[i] = max_tokens[i];
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->rate[i] = INVALID_RATE;
+  record->ntp_timeout_rate = INVALID_RATE;
+  record->drop_flags = 0;
+
+  return record;
+}
+
+/* ================================================== */
+
+static int
+expand_hashtable(void)
+{
+  ARR_Instance old_records;
+  Record *old_record, *new_record;
+  unsigned int i;
+
+  old_records = records;
+
+  if (2 * slots > max_slots)
+    return 0;
+
+  records = ARR_CreateInstance(sizeof (Record));
+
+  slots = MAX(MIN_SLOTS, 2 * slots);
+  assert(slots <= max_slots);
+
+  ARR_SetSize(records, slots * SLOT_SIZE);
+
+  /* Mark all new records as empty */
+  for (i = 0; i < slots * SLOT_SIZE; i++) {
+    new_record = ARR_GetElement(records, i);
+    new_record->ip_addr.family = IPADDR_UNSPEC;
+  }
+
+  if (!old_records)
+    return 1;
+
+  /* Copy old records to the new hash table */
+  for (i = 0; i < ARR_GetSize(old_records); i++) {
+    old_record = ARR_GetElement(old_records, i);
+    if (old_record->ip_addr.family == IPADDR_UNSPEC)
+      continue;
+
+    new_record = get_record(&old_record->ip_addr);
+
+    assert(new_record);
+    *new_record = *old_record;
+  }
+
+  ARR_DestroyInstance(old_records);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_bucket_params(int interval, int burst, uint16_t *max_tokens,
+                  uint16_t *tokens_per_packet, int *token_shift)
+{
+  interval = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
+  burst = CLAMP(MIN_LIMIT_BURST, burst, MAX_LIMIT_BURST);
+
+  if (interval >= -TS_FRAC) {
+    /* Find the smallest shift with which the maximum number fits in 16 bits */
+    for (*token_shift = 0; *token_shift < interval + TS_FRAC; (*token_shift)++) {
+      if (burst << (TS_FRAC + interval - *token_shift) < 1U << 16)
+        break;
+    }
+  } else {
+    /* Coarse rate limiting */
+    *token_shift = interval + TS_FRAC;
+    *tokens_per_packet = 1;
+    burst = MAX(1U << -*token_shift, burst);
+  }
+
+  *tokens_per_packet = 1U << (TS_FRAC + interval - *token_shift);
+  *max_tokens = *tokens_per_packet * burst;
+
+  DEBUG_LOG("Tokens max %d packet %d shift %d",
+            *max_tokens, *tokens_per_packet, *token_shift);
+}
+
+/* ================================================== */
+
+void
+CLG_Initialise(void)
+{
+  int i, interval, burst, lrate, slots2;
+
+  for (i = 0; i < MAX_SERVICES; i++) {
+    max_tokens[i] = 0;
+    tokens_per_hit[i] = 0;
+    token_shift[i] = 0;
+    leak_rate[i] = 0;
+    limit_interval[i] = MIN_LIMIT_INTERVAL;
+
+    switch (i) {
+      case CLG_NTP:
+        if (!CNF_GetNTPRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_NTSKE:
+        if (!CNF_GetNtsRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_CMDMON:
+        if (!CNF_GetCommandRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      default:
+        assert(0);
+    }
+
+    set_bucket_params(interval, burst, &max_tokens[i], &tokens_per_hit[i], &token_shift[i]);
+    leak_rate[i] = CLAMP(MIN_LEAK_RATE, lrate, MAX_LEAK_RATE);
+    limit_interval[i] = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
+  }
+
+  active = !CNF_GetNoClientLog();
+  if (!active) {
+    for (i = 0; i < MAX_SERVICES; i++) {
+      if (leak_rate[i] != 0)
+        LOG_FATAL("Rate limiting cannot be enabled with noclientlog");
+    }
+    return;
+  }
+
+  /* Calculate the maximum number of slots that can be allocated in the
+     configured memory limit.  Take into account expanding of the hash
+     table where two copies exist at the same time. */
+  max_slots = CNF_GetClientLogLimit() /
+              ((sizeof (Record) + sizeof (NtpTimestamps)) * SLOT_SIZE * 3 / 2);
+  max_slots = CLAMP(MIN_SLOTS, max_slots, MAX_SLOTS);
+  for (slots2 = 0; 1U << (slots2 + 1) <= max_slots; slots2++)
+    ;
+
+  DEBUG_LOG("Max records %u", 1U << (slots2 + SLOT_BITS));
+
+  slots = 0;
+  records = NULL;
+
+  expand_hashtable();
+
+  UTI_GetRandomBytes(&ts_offset, sizeof (ts_offset));
+  ts_offset %= NSEC_PER_SEC / (1U << TS_FRAC);
+
+  ntp_ts_map.timestamps = NULL;
+  ntp_ts_map.first = 0;
+  ntp_ts_map.size = 0;
+  ntp_ts_map.max_size = 1U << (slots2 + SLOT_BITS);
+  ntp_ts_map.cached_index = 0;
+  ntp_ts_map.cached_rx_ts = 0ULL;
+  ntp_ts_map.slew_epoch = 0;
+  ntp_ts_map.slew_offset = 0.0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+}
+
+/* ================================================== */
+
+void
+CLG_Finalise(void)
+{
+  if (!active)
+    return;
+
+  ARR_DestroyInstance(records);
+  if (ntp_ts_map.timestamps)
+    ARR_DestroyInstance(ntp_ts_map.timestamps);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+}
+
+/* ================================================== */
+
+static uint32_t
+get_ts_from_timespec(struct timespec *ts)
+{
+  uint32_t sec = ts->tv_sec, nsec = ts->tv_nsec;
+
+  nsec += ts_offset;
+  if (nsec >= NSEC_PER_SEC) {
+    nsec -= NSEC_PER_SEC;
+    sec++;
+  }
+
+  /* This is fast and accurate enough */
+  return sec << TS_FRAC | (140740U * (nsec >> 15)) >> (32 - TS_FRAC);
+}
+
+/* ================================================== */
+
+static void
+update_record(CLG_Service service, Record *record, struct timespec *now)
+{
+  uint32_t interval, now_ts, prev_hit, tokens;
+  int interval2, tshift, mtokens;
+  int8_t *rate;
+
+  now_ts = get_ts_from_timespec(now);
+
+  prev_hit = record->last_hit[service];
+  record->last_hit[service] = now_ts;
+  record->hits[service]++;
+
+  interval = now_ts - prev_hit;
+
+  if (prev_hit == INVALID_TS || (int32_t)interval < 0)
+    return;
+
+  tshift = token_shift[service];
+  mtokens = max_tokens[service];
+
+  if (tshift >= 0)
+    tokens = (now_ts >> tshift) - (prev_hit >> tshift);
+  else if (now_ts - prev_hit > mtokens)
+    tokens = mtokens;
+  else
+    tokens = (now_ts - prev_hit) << -tshift;
+  record->tokens[service] = MIN(record->tokens[service] + tokens, mtokens);
+
+  /* Convert the interval to scaled and rounded log2 */
+  if (interval) {
+    interval += interval >> 1;
+    for (interval2 = -RATE_SCALE * TS_FRAC; interval2 < -MIN_RATE;
+         interval2 += RATE_SCALE) {
+      if (interval <= 1)
+        break;
+      interval >>= 1;
+    }
+  } else {
+    interval2 = -RATE_SCALE * (TS_FRAC + 1);
+  }
+
+  /* For the NTP service, update one of the two rates depending on whether
+     the previous request of the client had a reply or it timed out */
+  rate = service == CLG_NTP && record->drop_flags & (1U << service) ?
+           &record->ntp_timeout_rate : &record->rate[service];
+
+  /* Update the rate in a rough approximation of exponential moving average */
+  if (*rate == INVALID_RATE) {
+    *rate = -interval2;
+  } else {
+    if (*rate < -interval2) {
+      (*rate)++;
+    } else if (*rate > -interval2) {
+      if (*rate > RATE_SCALE * 5 / 2 - interval2)
+        *rate = RATE_SCALE * 5 / 2 - interval2;
+      else
+        *rate = (*rate - interval2 - 1) / 2;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+get_index(Record *record)
+{
+  return record - (Record *)ARR_GetElements(records);
+}
+
+/* ================================================== */
+
+int
+CLG_GetClientIndex(IPAddr *client)
+{
+  Record *record;
+
+  record = get_record(client);
+  if (record == NULL)
+    return -1;
+
+  return get_index(record);
+}
+
+/* ================================================== */
+
+static void
+check_service_number(CLG_Service service)
+{
+  assert(service >= 0 && service <= MAX_SERVICES);
+}
+
+/* ================================================== */
+
+int
+CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now)
+{
+  Record *record;
+
+  check_service_number(service);
+
+  total_hits[service]++;
+
+  record = get_record(client);
+  if (record == NULL)
+    return -1;
+
+  update_record(service, record, now);
+
+  DEBUG_LOG("service %d hits %"PRIu32" rate %d trate %d tokens %d",
+            (int)service, record->hits[service], record->rate[service],
+            service == CLG_NTP ? record->ntp_timeout_rate : INVALID_RATE,
+            record->tokens[service]);
+
+  return get_index(record);
+}
+
+/* ================================================== */
+
+static int
+limit_response_random(int leak_rate)
+{
+  static uint32_t rnd;
+  static int bits_left = 0;
+  int r;
+
+  if (bits_left < leak_rate) {
+    UTI_GetRandomBytes(&rnd, sizeof (rnd));
+    bits_left = 8 * sizeof (rnd);
+  }
+
+  /* Return zero on average once per 2^leak_rate */
+  r = rnd % (1U << leak_rate) ? 1 : 0;
+  rnd >>= leak_rate;
+  bits_left -= leak_rate;
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+CLG_LimitServiceRate(CLG_Service service, int index)
+{
+  Record *record;
+  int drop;
+
+  check_service_number(service);
+
+  if (tokens_per_hit[service] == 0)
+    return 0;
+
+  record = ARR_GetElement(records, index);
+  record->drop_flags &= ~(1U << service);
+
+  if (record->tokens[service] >= tokens_per_hit[service]) {
+    record->tokens[service] -= tokens_per_hit[service];
+    return 0;
+  }
+
+  drop = limit_response_random(leak_rate[service]);
+
+  /* Poorly implemented NTP clients can send requests at a higher rate
+     when they are not getting replies.  If the request rate seems to be more
+     than twice as much as when replies are sent, give up on rate limiting to
+     reduce the amount of traffic.  Invert the sense of the leak to respond to
+     most of the requests, but still keep the estimated rate updated. */
+  if (service == CLG_NTP && record->ntp_timeout_rate != INVALID_RATE &&
+      record->ntp_timeout_rate > record->rate[service] + RATE_SCALE)
+    drop = !drop;
+
+  if (!drop) {
+    record->tokens[service] = 0;
+    return 0;
+  }
+
+  record->drop_flags |= 1U << service;
+  record->drops[service]++;
+  total_drops[service]++;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CLG_UpdateNtpStats(int auth, NTP_Timestamp_Source rx_ts_src, NTP_Timestamp_Source tx_ts_src)
+{
+  if (auth)
+    total_ntp_auth_hits++;
+  if (rx_ts_src >= 0 && rx_ts_src <= MAX_NTP_TS)
+    total_ntp_rx_timestamps[rx_ts_src]++;
+  if (tx_ts_src >= 0 && tx_ts_src <= MAX_NTP_TS)
+    total_ntp_tx_timestamps[tx_ts_src]++;
+}
+
+/* ================================================== */
+
+int
+CLG_GetNtpMinPoll(void)
+{
+  return limit_interval[CLG_NTP];
+}
+
+/* ================================================== */
+
+static NtpTimestamps *
+get_ntp_tss(uint32_t index)
+{
+  return ARR_GetElement(ntp_ts_map.timestamps,
+                        (ntp_ts_map.first + index) & (ntp_ts_map.max_size - 1));
+}
+
+/* ================================================== */
+
+static int
+find_ntp_rx_ts(uint64_t rx_ts, uint32_t *index)
+{
+  uint64_t rx_x, rx_lo, rx_hi, step;
+  uint32_t i, x, lo, hi;
+
+  if (ntp_ts_map.cached_rx_ts == rx_ts && rx_ts != 0ULL) {
+    *index = ntp_ts_map.cached_index;
+    return 1;
+  }
+
+  if (ntp_ts_map.size == 0) {
+    *index = 0;
+    return 0;
+  }
+
+  lo = 0;
+  hi = ntp_ts_map.size - 1;
+  rx_lo = get_ntp_tss(lo)->rx_ts;
+  rx_hi = get_ntp_tss(hi)->rx_ts;
+
+  /* Check for ts < lo before ts > hi to trim timestamps from "future" later
+     if both conditions are true to not break the order of the endpoints.
+     Compare timestamps by their difference to allow adjacent NTP eras. */
+  if ((int64_t)(rx_ts - rx_lo) < 0) {
+    *index = 0;
+    return 0;
+  } else if ((int64_t)(rx_ts - rx_hi) > 0) {
+    *index = ntp_ts_map.size;
+    return 0;
+  }
+
+  /* Perform a combined linear interpolation and binary search */
+
+  for (i = 0; ; i++) {
+    if (rx_ts == rx_hi) {
+      *index = ntp_ts_map.cached_index = hi;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (rx_ts == rx_lo) {
+      *index = ntp_ts_map.cached_index = lo;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (lo + 1 == hi) {
+      *index = hi;
+      return 0;
+    }
+
+    if (hi - lo > 3 && i % 2 == 0) {
+      step = (rx_hi - rx_lo) / (hi - lo);
+      if (step == 0)
+        step = 1;
+      x = lo + (rx_ts - rx_lo) / step;
+    } else {
+      x = lo + (hi - lo) / 2;
+    }
+
+    if (x <= lo)
+      x = lo + 1;
+    else if (x >= hi)
+      x = hi - 1;
+
+    rx_x = get_ntp_tss(x)->rx_ts;
+
+    if ((int64_t)(rx_x - rx_ts) <= 0) {
+      lo = x;
+      rx_lo = rx_x;
+    } else {
+      hi = x;
+      rx_hi = rx_x;
+    }
+  }
+}
+
+/* ================================================== */
+
+static uint64_t
+ntp64_to_int64(NTP_int64 *ts)
+{
+  return (uint64_t)ntohl(ts->hi) << 32 | ntohl(ts->lo);
+}
+
+/* ================================================== */
+
+static void
+int64_to_ntp64(uint64_t ts, NTP_int64 *ntp_ts)
+{
+  ntp_ts->hi = htonl(ts >> 32);
+  ntp_ts->lo = htonl(ts);
+}
+
+/* ================================================== */
+
+static uint32_t
+push_ntp_tss(uint32_t index)
+{
+  if (ntp_ts_map.size < ntp_ts_map.max_size) {
+    ntp_ts_map.size++;
+  } else {
+    ntp_ts_map.first = (ntp_ts_map.first + 1) % (ntp_ts_map.max_size);
+    if (index > 0)
+      index--;
+  }
+
+  return index;
+}
+
+/* ================================================== */
+
+static void
+set_ntp_tx(NtpTimestamps *tss, NTP_int64 *rx_ts, struct timespec *tx_ts,
+           NTP_Timestamp_Source tx_src)
+{
+  struct timespec ts;
+
+  if (!tx_ts) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  UTI_Ntp64ToTimespec(rx_ts, &ts);
+  UTI_DiffTimespecs(&ts, tx_ts, &ts);
+
+  if (ts.tv_sec < -2 || ts.tv_sec > 1) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  tss->tx_ts_offset = (int32_t)ts.tv_nsec + (int32_t)ts.tv_sec * (int32_t)NSEC_PER_SEC;
+  tss->flags |= NTPTS_VALID_TX;
+  tss->tx_ts_source = tx_src;
+}
+
+/* ================================================== */
+
+static void
+get_ntp_tx(NtpTimestamps *tss, struct timespec *tx_ts, NTP_Timestamp_Source *tx_src)
+{
+  int32_t offset = tss->tx_ts_offset;
+  NTP_int64 ntp_ts;
+
+  if (tss->flags & NTPTS_VALID_TX) {
+    int64_to_ntp64(tss->rx_ts, &ntp_ts);
+    UTI_Ntp64ToTimespec(&ntp_ts, tx_ts);
+    if (offset >= (int32_t)NSEC_PER_SEC) {
+      offset -= NSEC_PER_SEC;
+      tx_ts->tv_sec++;
+    }
+    tx_ts->tv_nsec += offset;
+    UTI_NormaliseTimespec(tx_ts);
+  } else {
+    UTI_ZeroTimespec(tx_ts);
+  }
+
+  *tx_src = tss->tx_ts_source;
+}
+
+/* ================================================== */
+
+void
+CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts, NTP_Timestamp_Source tx_src)
+{
+  NtpTimestamps *tss;
+  uint32_t i, index;
+  uint64_t rx;
+
+  if (!active)
+    return;
+
+  /* Allocate the array on first use */
+  if (!ntp_ts_map.timestamps) {
+    ntp_ts_map.timestamps = ARR_CreateInstance(sizeof (NtpTimestamps));
+    ARR_SetSize(ntp_ts_map.timestamps, ntp_ts_map.max_size);
+  }
+
+  rx = ntp64_to_int64(rx_ts);
+
+  if (rx == 0ULL)
+    return;
+
+  /* Disable the RX timestamp if it already exists to avoid responding
+     with a wrong TX timestamp */
+  if (find_ntp_rx_ts(rx, &index)) {
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+    return;
+  }
+
+  assert(index <= ntp_ts_map.size);
+
+  if (index == ntp_ts_map.size) {
+    /* Increase the size or drop the oldest timestamp to make room for
+       the new timestamp */
+    index = push_ntp_tss(index);
+  } else {
+    /* Trim timestamps in distant future after backward step */
+    while (index < ntp_ts_map.size &&
+           get_ntp_tss(ntp_ts_map.size - 1)->rx_ts - rx > NTPTS_FUTURE_LIMIT)
+      ntp_ts_map.size--;
+
+    /* Insert the timestamp if it is close to the latest timestamp.
+       Otherwise, replace the closest older or the oldest timestamp. */
+    if (index + NTPTS_INSERT_LIMIT >= ntp_ts_map.size) {
+      index = push_ntp_tss(index);
+      for (i = ntp_ts_map.size - 1; i > index; i--)
+        *get_ntp_tss(i) = *get_ntp_tss(i - 1);
+    } else {
+      if (index > 0)
+        index--;
+    }
+  }
+
+  ntp_ts_map.cached_index = index;
+  ntp_ts_map.cached_rx_ts = rx;
+
+  tss = get_ntp_tss(index);
+  tss->rx_ts = rx;
+  tss->flags = 0;
+  tss->slew_epoch = ntp_ts_map.slew_epoch;
+  set_ntp_tx(tss, rx_ts, tx_ts, tx_src);
+
+  DEBUG_LOG("Saved RX+TX index=%"PRIu32" first=%"PRIu32" size=%"PRIu32,
+            index, ntp_ts_map.first, ntp_ts_map.size);
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  /* Drop all timestamps on unknown step */
+  if (change_type == LCL_ChangeUnknownStep) {
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+  }
+
+  ntp_ts_map.slew_epoch++;
+  ntp_ts_map.slew_offset = doffset;
+}
+
+/* ================================================== */
+
+void
+CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  /* If the RX timestamp was captured before the last correction of the clock,
+     remove the adjustment from the TX timestamp */
+  if ((uint16_t)(get_ntp_tss(index)->slew_epoch + 1U) == ntp_ts_map.slew_epoch)
+    UTI_AddDoubleToTimespec(tx_ts, ntp_ts_map.slew_offset, tx_ts);
+}
+
+/* ================================================== */
+
+void
+CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                         NTP_Timestamp_Source tx_src)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  set_ntp_tx(get_ntp_tss(index), rx_ts, tx_ts, tx_src);
+}
+
+/* ================================================== */
+
+int
+CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                      NTP_Timestamp_Source *tx_src)
+{
+  NtpTimestamps *tss;
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return 0;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return 0;
+
+  tss = get_ntp_tss(index);
+
+  if (tss->flags & NTPTS_DISABLED)
+    return 0;
+
+  get_ntp_tx(tss, tx_ts, tx_src);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CLG_DisableNtpTimestamps(NTP_int64 *rx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+
+  /* This assumes the function is called only to prevent multiple
+     interleaved responses to the same timestamp */
+  total_ntp_interleaved_hits++;
+}
+
+/* ================================================== */
+
+int
+CLG_GetNumberOfIndices(void)
+{
+  if (!active)
+    return -1;
+
+  return ARR_GetSize(records);
+}
+
+/* ================================================== */
+
+static int get_interval(int rate)
+{
+  if (rate == INVALID_RATE)
+    return 127;
+
+  rate += rate > 0 ? RATE_SCALE / 2 : -RATE_SCALE / 2;
+
+  return rate / -RATE_SCALE;
+}
+
+/* ================================================== */
+
+static uint32_t get_last_ago(uint32_t x, uint32_t y)
+{
+  if (y == INVALID_TS || (int32_t)(x - y) < 0)
+    return -1;
+
+  return (x - y) >> TS_FRAC;
+}
+
+/* ================================================== */
+
+int
+CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                 RPT_ClientAccessByIndex_Report *report, struct timespec *now)
+{
+  Record *record;
+  uint32_t now_ts;
+  int i, r;
+
+  if (!active || index < 0 || index >= ARR_GetSize(records))
+    return 0;
+
+  record = ARR_GetElement(records, index);
+
+  if (record->ip_addr.family == IPADDR_UNSPEC)
+    return 0;
+
+  if (min_hits == 0) {
+    r = 1;
+  } else {
+    for (i = r = 0; i < MAX_SERVICES; i++) {
+      if (record->hits[i] >= min_hits) {
+        r = 1;
+        break;
+      }
+    }
+  }
+
+  if (r) {
+    now_ts = get_ts_from_timespec(now);
+
+    report->ip_addr = record->ip_addr;
+    report->ntp_hits = record->hits[CLG_NTP];
+    report->nke_hits = record->hits[CLG_NTSKE];
+    report->cmd_hits = record->hits[CLG_CMDMON];
+    report->ntp_drops = record->drops[CLG_NTP];
+    report->nke_drops = record->drops[CLG_NTSKE];
+    report->cmd_drops = record->drops[CLG_CMDMON];
+    report->ntp_interval = get_interval(record->rate[CLG_NTP]);
+    report->nke_interval = get_interval(record->rate[CLG_NTSKE]);
+    report->cmd_interval = get_interval(record->rate[CLG_CMDMON]);
+    report->ntp_timeout_interval = get_interval(record->ntp_timeout_rate);
+    report->last_ntp_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTP]);
+    report->last_nke_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTSKE]);
+    report->last_cmd_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_CMDMON]);
+  }
+
+  if (reset) {
+    for (i = 0; i < MAX_SERVICES; i++) {
+      record->hits[i] = 0;
+      record->drops[i] = 0;
+    }
+  }
+
+  return r;
+}
+
+/* ================================================== */
+
+void
+CLG_GetServerStatsReport(RPT_ServerStatsReport *report)
+{
+  report->ntp_hits = total_hits[CLG_NTP];
+  report->nke_hits = total_hits[CLG_NTSKE];
+  report->cmd_hits = total_hits[CLG_CMDMON];
+  report->ntp_drops = total_drops[CLG_NTP];
+  report->nke_drops = total_drops[CLG_NTSKE];
+  report->cmd_drops = total_drops[CLG_CMDMON];
+  report->log_drops = total_record_drops;
+  report->ntp_auth_hits = total_ntp_auth_hits;
+  report->ntp_interleaved_hits = total_ntp_interleaved_hits;
+  report->ntp_timestamps = ntp_ts_map.size;
+  report->ntp_span_seconds = ntp_ts_map.size > 1 ?
+                             (get_ntp_tss(ntp_ts_map.size - 1)->rx_ts -
+                              get_ntp_tss(0)->rx_ts) >> 32 : 0;
+  report->ntp_daemon_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_DAEMON];
+  report->ntp_daemon_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_DAEMON];
+  report->ntp_kernel_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_KERNEL];
+  report->ntp_kernel_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_KERNEL];
+  report->ntp_hw_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_HARDWARE];
+  report->ntp_hw_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_HARDWARE];
+}
diff --git a/clientlog.h b/clientlog.h
new file mode 100644
index 0000000..9ea0a3f
--- /dev/null
+++ b/clientlog.h
@@ -0,0 +1,67 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module contains facilities for logging access by clients.
+
+  */
+
+#ifndef GOT_CLIENTLOG_H
+#define GOT_CLIENTLOG_H
+
+#include "sysincl.h"
+#include "reports.h"
+
+typedef enum {
+  CLG_NTP = 0,
+  CLG_NTSKE,
+  CLG_CMDMON,
+} CLG_Service;
+
+extern void CLG_Initialise(void);
+extern void CLG_Finalise(void);
+extern int CLG_GetClientIndex(IPAddr *client);
+extern int CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now);
+extern int CLG_LimitServiceRate(CLG_Service service, int index);
+extern void CLG_UpdateNtpStats(int auth, NTP_Timestamp_Source rx_ts_src,
+                               NTP_Timestamp_Source tx_ts_src);
+extern int CLG_GetNtpMinPoll(void);
+
+/* Functions to save and retrieve timestamps for server interleaved mode */
+extern void CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                  NTP_Timestamp_Source tx_src);
+extern void CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                     NTP_Timestamp_Source tx_src);
+extern int CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                 NTP_Timestamp_Source *tx_src);
+extern void CLG_DisableNtpTimestamps(NTP_int64 *rx_ts);
+
+/* And some reporting functions, for use by chronyc. */
+
+extern int CLG_GetNumberOfIndices(void);
+extern int CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                            RPT_ClientAccessByIndex_Report *report,
+                                            struct timespec *now);
+extern void CLG_GetServerStatsReport(RPT_ServerStatsReport *report);
+
+#endif /* GOT_CLIENTLOG_H */
diff --git a/cmac.h b/cmac.h
new file mode 100644
index 0000000..935820d
--- /dev/null
+++ b/cmac.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for CMAC.
+
+  */
+
+#ifndef GOT_CMAC_H
+#define GOT_CMAC_H
+
+/* Avoid overlapping with the hash enumeration */
+typedef enum {
+  CMC_INVALID = 0,
+  CMC_AES128 = 13,
+  CMC_AES256 = 14,
+} CMC_Algorithm;
+
+typedef struct CMC_Instance_Record *CMC_Instance;
+
+extern int CMC_GetKeyLength(CMC_Algorithm algorithm);
+extern CMC_Instance CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key,
+                                       int length);
+extern int CMC_Hash(CMC_Instance inst, const void *in, int in_len,
+                    unsigned char *out, int out_len);
+extern void CMC_DestroyInstance(CMC_Instance inst);
+
+#endif
+
diff --git a/cmac_gnutls.c b/cmac_gnutls.c
new file mode 100644
index 0000000..d1cd550
--- /dev/null
+++ b/cmac_gnutls.c
@@ -0,0 +1,189 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  CMAC using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "cmac.h"
+#include "hash.h"
+#include "logging.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+  gnutls_mac_algorithm_t algorithm;
+  gnutls_hmac_hd_t mac;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  DEBUG_LOG("Initialised");
+  gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  assert(gnutls_initialised);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_mac_algorithm_t
+get_mac_algorithm(CMC_Algorithm algorithm)
+{
+  switch (algorithm) {
+    case CMC_AES128:
+      return GNUTLS_MAC_AES_CMAC_128;
+    case CMC_AES256:
+      return GNUTLS_MAC_AES_CMAC_256;
+    default:
+      return GNUTLS_MAC_UNKNOWN;
+  }
+}
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  gnutls_mac_algorithm_t malgo = get_mac_algorithm(algorithm);
+  int len;
+
+  if (malgo == GNUTLS_MAC_UNKNOWN)
+    return 0;
+
+  len = gnutls_hmac_get_key_size(malgo);
+
+  if (len < 0)
+    return 0;
+
+  return len;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  gnutls_hmac_hd_t handle;
+  CMC_Instance inst;
+
+  int r;
+
+  if (instance_counter == 0)
+    init_gnutls();
+
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+    goto error;
+
+  r = gnutls_hmac_init(&handle, get_mac_algorithm(algorithm), key, length);
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "mac", gnutls_strerror(r));
+    goto error;
+  }
+
+  inst = MallocNew(struct CMC_Instance_Record);
+  inst->algorithm = get_mac_algorithm(algorithm);
+  inst->mac = handle;
+
+  instance_counter++;
+
+  return inst;
+
+error:
+  if (instance_counter == 0)
+    deinit_gnutls();
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  int hash_len;
+
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
+  hash_len = gnutls_hmac_get_len(inst->algorithm);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hmac(inst->mac, in, in_len) < 0) {
+    /* Reset the state */
+    gnutls_hmac_output(inst->mac, buf);
+    return 0;
+  }
+
+  gnutls_hmac_output(inst->mac, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+  gnutls_hmac_deinit(inst->mac, NULL);
+  Free(inst);
+
+  instance_counter--;
+  if (instance_counter == 0)
+    deinit_gnutls();
+}
diff --git a/cmac_nettle.c b/cmac_nettle.c
new file mode 100644
index 0000000..5b2c0d4
--- /dev/null
+++ b/cmac_nettle.c
@@ -0,0 +1,117 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Support for AES128 and AES256 CMAC in Nettle.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <nettle/cmac.h>
+
+#include "cmac.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+  int key_length;
+  union {
+    struct cmac_aes128_ctx aes128;
+    struct cmac_aes256_ctx aes256;
+  } context;
+};
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  if (algorithm == CMC_AES128)
+    return AES128_KEY_SIZE;
+  else if (algorithm == CMC_AES256)
+    return AES256_KEY_SIZE;
+  return 0;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  CMC_Instance inst;
+
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+    return NULL;
+
+  inst = MallocNew(struct CMC_Instance_Record);
+  inst->key_length = length;
+
+  switch (length) {
+    case AES128_KEY_SIZE:
+      cmac_aes128_set_key(&inst->context.aes128, key);
+      break;
+    case AES256_KEY_SIZE:
+      cmac_aes256_set_key(&inst->context.aes256, key);
+      break;
+    default:
+      assert(0);
+  }
+
+  return inst;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
+  if (out_len > CMAC128_DIGEST_SIZE)
+    out_len = CMAC128_DIGEST_SIZE;
+
+  switch (inst->key_length) {
+    case AES128_KEY_SIZE:
+      cmac_aes128_update(&inst->context.aes128, in_len, in);
+      cmac_aes128_digest(&inst->context.aes128, out_len, out);
+      break;
+    case AES256_KEY_SIZE:
+      cmac_aes256_update(&inst->context.aes256, in_len, in);
+      cmac_aes256_digest(&inst->context.aes256, out_len, out);
+      break;
+    default:
+      assert(0);
+  }
+
+  return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+  Free(inst);
+}
diff --git a/cmdmon.c b/cmdmon.c
new file mode 100644
index 0000000..c2c5bf0
--- /dev/null
+++ b/cmdmon.c
@@ -0,0 +1,1869 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2016, 2018-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Command and monitoring module in the main program
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "cmdmon.h"
+#include "candm.h"
+#include "sched.h"
+#include "util.h"
+#include "logging.h"
+#include "keys.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "smooth.h"
+#include "socket.h"
+#include "sources.h"
+#include "sourcestats.h"
+#include "reference.h"
+#include "manual.h"
+#include "memory.h"
+#include "nts_ke_server.h"
+#include "local.h"
+#include "addrfilt.h"
+#include "conf.h"
+#include "rtc.h"
+#include "pktlength.h"
+#include "clientlog.h"
+#include "refclock.h"
+
+/* ================================================== */
+
+#define INVALID_SOCK_FD (-5)
+
+/* File descriptors for command and monitoring sockets */
+static int sock_fdu;
+static int sock_fd4;
+static int sock_fd6;
+
+/* Flag indicating the IPv4 socket is bound to an address */
+static int bound_sock_fd4;
+
+/* Flag indicating whether this module has been initialised or not */
+static int initialised = 0;
+
+/* ================================================== */
+/* Array of permission levels for command types */
+
+static const char permissions[] = {
+  PERMIT_OPEN, /* NULL */
+  PERMIT_AUTH, /* ONLINE */
+  PERMIT_AUTH, /* OFFLINE */
+  PERMIT_AUTH, /* BURST */
+  PERMIT_AUTH, /* MODIFY_MINPOLL */
+  PERMIT_AUTH, /* MODIFY_MAXPOLL */
+  PERMIT_AUTH, /* DUMP */
+  PERMIT_AUTH, /* MODIFY_MAXDELAY */
+  PERMIT_AUTH, /* MODIFY_MAXDELAYRATIO */
+  PERMIT_AUTH, /* MODIFY_MAXUPDATESKEW */
+  PERMIT_OPEN, /* LOGON */
+  PERMIT_AUTH, /* SETTIME */
+  PERMIT_AUTH, /* LOCAL */
+  PERMIT_AUTH, /* MANUAL */
+  PERMIT_OPEN, /* N_SOURCES */
+  PERMIT_OPEN, /* SOURCE_DATA */
+  PERMIT_AUTH, /* REKEY */
+  PERMIT_AUTH, /* ALLOW */
+  PERMIT_AUTH, /* ALLOWALL */
+  PERMIT_AUTH, /* DENY */
+  PERMIT_AUTH, /* DENYALL */
+  PERMIT_AUTH, /* CMDALLOW */
+  PERMIT_AUTH, /* CMDALLOWALL */
+  PERMIT_AUTH, /* CMDDENY */
+  PERMIT_AUTH, /* CMDDENYALL */
+  PERMIT_AUTH, /* ACCHECK */
+  PERMIT_AUTH, /* CMDACCHECK */
+  PERMIT_AUTH, /* ADD_SERVER */
+  PERMIT_AUTH, /* ADD_PEER */
+  PERMIT_AUTH, /* DEL_SOURCE */
+  PERMIT_AUTH, /* WRITERTC */
+  PERMIT_AUTH, /* DFREQ */
+  PERMIT_AUTH, /* DOFFSET */
+  PERMIT_OPEN, /* TRACKING */
+  PERMIT_OPEN, /* SOURCESTATS */
+  PERMIT_OPEN, /* RTCREPORT */
+  PERMIT_AUTH, /* TRIMRTC */
+  PERMIT_AUTH, /* CYCLELOGS */
+  PERMIT_AUTH, /* SUBNETS_ACCESSED */
+  PERMIT_AUTH, /* CLIENT_ACCESSES (by subnet) */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX */
+  PERMIT_OPEN, /* MANUAL_LIST */
+  PERMIT_AUTH, /* MANUAL_DELETE */
+  PERMIT_AUTH, /* MAKESTEP */
+  PERMIT_OPEN, /* ACTIVITY */
+  PERMIT_AUTH, /* MODIFY_MINSTRATUM */
+  PERMIT_AUTH, /* MODIFY_POLLTARGET */
+  PERMIT_AUTH, /* MODIFY_MAXDELAYDEVRATIO */
+  PERMIT_AUTH, /* RESELECT */
+  PERMIT_AUTH, /* RESELECTDISTANCE */
+  PERMIT_AUTH, /* MODIFY_MAKESTEP */
+  PERMIT_OPEN, /* SMOOTHING */
+  PERMIT_AUTH, /* SMOOTHTIME */
+  PERMIT_AUTH, /* REFRESH */
+  PERMIT_AUTH, /* SERVER_STATS */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX2 */
+  PERMIT_AUTH, /* LOCAL2 */
+  PERMIT_AUTH, /* NTP_DATA */
+  PERMIT_AUTH, /* ADD_SERVER2 */
+  PERMIT_AUTH, /* ADD_PEER2 */
+  PERMIT_AUTH, /* ADD_SERVER3 */
+  PERMIT_AUTH, /* ADD_PEER3 */
+  PERMIT_AUTH, /* SHUTDOWN */
+  PERMIT_AUTH, /* ONOFFLINE */
+  PERMIT_AUTH, /* ADD_SOURCE */
+  PERMIT_OPEN, /* NTP_SOURCE_NAME */
+  PERMIT_AUTH, /* RESET_SOURCES */
+  PERMIT_AUTH, /* AUTH_DATA */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX3 */
+  PERMIT_AUTH, /* SELECT_DATA */
+  PERMIT_AUTH, /* RELOAD_SOURCES */
+  PERMIT_AUTH, /* DOFFSET2 */
+  PERMIT_AUTH, /* MODIFY_SELECTOPTS */
+};
+
+/* ================================================== */
+
+/* This authorisation table is used for checking whether particular
+   machines are allowed to make command and monitoring requests. */
+static ADF_AuthTable access_auth_table;
+
+/* ================================================== */
+/* Forward prototypes */
+static void read_from_cmd_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static int
+open_socket(int family)
+{
+  const char *local_path, *iface;
+  IPSockAddr local_addr;
+  int sock_fd, port;
+
+  switch (family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+      port = CNF_GetCommandPort();
+      if (port == 0 || !SCK_IsIpFamilyEnabled(family))
+        return INVALID_SOCK_FD;
+
+      CNF_GetBindCommandAddress(family, &local_addr.ip_addr);
+      local_addr.port = port;
+      iface = CNF_GetBindCommandInterface();
+
+      sock_fd = SCK_OpenUdpSocket(NULL, &local_addr, iface, SCK_FLAG_RX_DEST_ADDR);
+      if (sock_fd < 0) {
+        LOG(LOGS_ERR, "Could not open command socket on %s",
+            UTI_IPSockAddrToString(&local_addr));
+        return INVALID_SOCK_FD;
+      }
+
+      if (family == IPADDR_INET4)
+        bound_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;
+
+      break;
+    case IPADDR_UNSPEC:
+      local_path = CNF_GetBindCommandPath();
+
+      sock_fd = SCK_OpenUnixDatagramSocket(NULL, local_path, 0);
+      if (sock_fd < 0) {
+        LOG(LOGS_ERR, "Could not open command socket on %s", local_path);
+        return INVALID_SOCK_FD;
+      }
+
+      break;
+    default:
+      assert(0);
+  }
+
+  /* Register handler for read events on the socket */
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_from_cmd_socket, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static void
+do_size_checks(void)
+{
+  int i, request_length, padding_length, reply_length;
+  CMD_Request request;
+  CMD_Reply reply;
+
+  assert(offsetof(CMD_Request, data) == 20);
+  assert(offsetof(CMD_Reply, data) == 28);
+
+  for (i = 0; i < N_REQUEST_TYPES; i++) {
+    request.version = PROTO_VERSION_NUMBER;
+    request.command = htons(i);
+    request_length = PKL_CommandLength(&request);
+    padding_length = PKL_CommandPaddingLength(&request);
+    if (padding_length > MAX_PADDING_LENGTH || padding_length > request_length ||
+        request_length > sizeof (CMD_Request) ||
+        (request_length && request_length < offsetof(CMD_Request, data)))
+      assert(0);
+  }
+
+  for (i = 1; i < N_REPLY_TYPES; i++) {
+    reply.reply = htons(i);
+    reply.status = STT_SUCCESS;
+    reply_length = PKL_ReplyLength(&reply);
+    if ((reply_length && reply_length < offsetof(CMD_Reply, data)) ||
+        reply_length > sizeof (CMD_Reply))
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+CAM_Initialise(void)
+{
+  assert(!initialised);
+  assert(sizeof (permissions) / sizeof (permissions[0]) == N_REQUEST_TYPES);
+  do_size_checks();
+
+  initialised = 1;
+
+  bound_sock_fd4 = 0;
+
+  sock_fdu = INVALID_SOCK_FD;
+  sock_fd4 = open_socket(IPADDR_INET4);
+  sock_fd6 = open_socket(IPADDR_INET6);
+
+  access_auth_table = ADF_CreateTable();
+}
+
+/* ================================================== */
+
+void
+CAM_Finalise(void)
+{
+  if (sock_fdu != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fdu);
+    SCK_RemoveSocket(sock_fdu);
+    SCK_CloseSocket(sock_fdu);
+    sock_fdu = INVALID_SOCK_FD;
+  }
+
+  if (sock_fd4 != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fd4);
+    SCK_CloseSocket(sock_fd4);
+    sock_fd4 = INVALID_SOCK_FD;
+  }
+
+  if (sock_fd6 != INVALID_SOCK_FD) {
+    SCH_RemoveFileHandler(sock_fd6);
+    SCK_CloseSocket(sock_fd6);
+    sock_fd6 = INVALID_SOCK_FD;
+  }
+
+  ADF_DestroyTable(access_auth_table);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void
+CAM_OpenUnixSocket(void)
+{
+  /* This is separated from CAM_Initialise() as it needs to be called when
+     the process has already dropped the root privileges */
+  if (CNF_GetBindCommandPath())
+    sock_fdu = open_socket(IPADDR_UNSPEC);
+}
+
+/* ================================================== */
+
+static void
+transmit_reply(int sock_fd, int request_length, SCK_Message *message)
+{
+  message->length = PKL_ReplyLength((CMD_Reply *)message->data);
+
+  if (request_length < message->length) {
+    DEBUG_LOG("Response longer than request req_len=%d res_len=%d",
+              request_length, message->length);
+    return;
+  }
+
+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  if (message->addr_type == SCK_ADDR_IP &&
+      !SCK_IsLinkLocalIPAddress(&message->remote_addr.ip.ip_addr))
+    message->if_index = INVALID_IF_INDEX;
+
+#if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
+  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
+  if (message->addr_type == SCK_ADDR_IP && message->local_addr.ip.family == IPADDR_INET4 &&
+      (sock_fd != sock_fd4 || bound_sock_fd4))
+    message->local_addr.ip.family = IPADDR_UNSPEC;
+#endif
+
+  if (!SCK_SendMessage(sock_fd, message, 0))
+    return;
+}
+  
+/* ================================================== */
+
+static void
+handle_dump(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  SRC_DumpSources();
+  NSR_DumpAuthData();
+  NKS_DumpKeys();
+}
+
+/* ================================================== */
+
+static void
+handle_online(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.online.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.online.address, &address);
+  if (!NSR_SetConnectivity(&mask, &address, SRC_ONLINE))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_offline(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.offline.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.offline.address, &address);
+  if (!NSR_SetConnectivity(&mask, &address, SRC_OFFLINE))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_onoffline(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  address.family = mask.family = IPADDR_UNSPEC;
+  if (!NSR_SetConnectivity(&mask, &address, SRC_MAYBE_ONLINE))
+    ;
+}
+
+/* ================================================== */
+
+static void
+handle_burst(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address, mask;
+
+  UTI_IPNetworkToHost(&rx_message->data.burst.mask, &mask);
+  UTI_IPNetworkToHost(&rx_message->data.burst.address, &address);
+  if (!NSR_InitiateSampleBurst(ntohl(rx_message->data.burst.n_good_samples),
+                               ntohl(rx_message->data.burst.n_total_samples),
+                               &mask, &address))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_minpoll(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMinpoll(&address,
+                         ntohl(rx_message->data.modify_minpoll.new_minpoll)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxpoll(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMaxpoll(&address,
+                         ntohl(rx_message->data.modify_minpoll.new_minpoll)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelay(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelay.address, &address);
+  if (!NSR_ModifyMaxdelay(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelay.new_max_delay)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelayratio(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelayratio.address, &address);
+  if (!NSR_ModifyMaxdelayratio(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelayratio.new_max_delay_ratio)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxdelaydevratio(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_maxdelaydevratio.address, &address);
+  if (!NSR_ModifyMaxdelaydevratio(&address,
+        UTI_FloatNetworkToHost(rx_message->data.modify_maxdelaydevratio.new_max_delay_dev_ratio)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_minstratum(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_minpoll.address, &address);
+  if (!NSR_ModifyMinstratum(&address,
+                            ntohl(rx_message->data.modify_minstratum.new_min_stratum)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_polltarget(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr address;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_polltarget.address, &address);
+  if (!NSR_ModifyPolltarget(&address,
+                            ntohl(rx_message->data.modify_polltarget.new_poll_target)))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_maxupdateskew(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  REF_ModifyMaxupdateskew(UTI_FloatNetworkToHost(rx_message->data.modify_maxupdateskew.new_max_update_skew));
+}
+
+/* ================================================== */
+
+static void
+handle_modify_makestep(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  REF_ModifyMakestep(ntohl(rx_message->data.modify_makestep.limit),
+                     UTI_FloatNetworkToHost(rx_message->data.modify_makestep.threshold));
+}
+
+/* ================================================== */
+
+static void
+handle_settime(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec ts;
+  double offset, dfreq_ppm, new_afreq_ppm;
+  UTI_TimespecNetworkToHost(&rx_message->data.settime.ts, &ts);
+  if (!MNL_IsEnabled()) {
+    tx_message->status = htons(STT_NOTENABLED);
+  } else if (MNL_AcceptTimestamp(&ts, &offset, &dfreq_ppm, &new_afreq_ppm)) {
+    tx_message->reply = htons(RPY_MANUAL_TIMESTAMP2);
+    tx_message->data.manual_timestamp.offset = UTI_FloatHostToNetwork(offset);
+    tx_message->data.manual_timestamp.dfreq_ppm = UTI_FloatHostToNetwork(dfreq_ppm);
+    tx_message->data.manual_timestamp.new_afreq_ppm = UTI_FloatHostToNetwork(new_afreq_ppm);
+  } else {
+    tx_message->status = htons(STT_FAILED);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_local(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (ntohl(rx_message->data.local.on_off)) {
+    REF_EnableLocal(ntohl(rx_message->data.local.stratum),
+                    UTI_FloatNetworkToHost(rx_message->data.local.distance),
+                    ntohl(rx_message->data.local.orphan));
+  } else {
+    REF_DisableLocal();
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_manual(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int option;
+  option = ntohl(rx_message->data.manual.option);
+  switch (option) {
+    case 0:
+      MNL_Disable();
+      break;
+    case 1:
+      MNL_Enable();
+      break;
+    case 2:
+      MNL_Reset();
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_n_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int n_sources;
+  n_sources = SRC_ReadNumberOfSources();
+  tx_message->reply = htons(RPY_N_SOURCES);
+  tx_message->data.n_sources.n_sources = htonl(n_sources);
+}
+
+/* ================================================== */
+
+static void
+handle_source_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SourceReport report;
+  struct timespec now_corr;
+
+  /* Get data */
+  SCH_GetLastEventTime(&now_corr, NULL, NULL);
+  if (SRC_ReportSource(ntohl(rx_message->data.source_data.index), &report, &now_corr)) {
+    switch (SRC_GetType(ntohl(rx_message->data.source_data.index))) {
+      case SRC_NTP:
+        NSR_ReportSource(&report, &now_corr);
+        break;
+      case SRC_REFCLOCK:
+        RCL_ReportSource(&report, &now_corr);
+        break;
+    }
+    
+    tx_message->reply  = htons(RPY_SOURCE_DATA);
+    
+    UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.source_data.ip_addr);
+    tx_message->data.source_data.stratum = htons(report.stratum);
+    tx_message->data.source_data.poll    = htons(report.poll);
+    switch (report.state) {
+      case RPT_NONSELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_NONSELECTABLE);
+        break;
+      case RPT_FALSETICKER:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_FALSETICKER);
+        break;
+      case RPT_JITTERY:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_JITTERY);
+        break;
+      case RPT_SELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTABLE);
+        break;
+      case RPT_UNSELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_UNSELECTED);
+        break;
+      case RPT_SELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTED);
+        break;
+    }
+    switch (report.mode) {
+      case RPT_NTP_CLIENT:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_CLIENT);
+        break;
+      case RPT_NTP_PEER:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_PEER);
+        break;
+      case RPT_LOCAL_REFERENCE:
+        tx_message->data.source_data.mode    = htons(RPY_SD_MD_REF);
+        break;
+    }
+    tx_message->data.source_data.flags = htons(0);
+    tx_message->data.source_data.reachability = htons(report.reachability);
+    tx_message->data.source_data.since_sample = htonl(report.latest_meas_ago);
+    tx_message->data.source_data.orig_latest_meas = UTI_FloatHostToNetwork(report.orig_latest_meas);
+    tx_message->data.source_data.latest_meas = UTI_FloatHostToNetwork(report.latest_meas);
+    tx_message->data.source_data.latest_meas_err = UTI_FloatHostToNetwork(report.latest_meas_err);
+  } else {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_rekey(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  KEY_Reload();
+  NKS_ReloadKeys();
+}
+
+/* ================================================== */
+
+static void
+handle_allowdeny(CMD_Request *rx_message, CMD_Reply *tx_message, int allow, int all)
+{
+  IPAddr ip;
+  int subnet_bits;
+
+  UTI_IPNetworkToHost(&rx_message->data.allow_deny.ip, &ip);
+  subnet_bits = ntohl(rx_message->data.allow_deny.subnet_bits);
+  if (!NCR_AddAccessRestriction(&ip, subnet_bits, allow, all))
+    tx_message->status = htons(STT_BADSUBNET);
+}
+
+/* ================================================== */
+
+static void
+handle_cmdallowdeny(CMD_Request *rx_message, CMD_Reply *tx_message, int allow, int all)
+{
+  IPAddr ip;
+  int subnet_bits;
+
+  UTI_IPNetworkToHost(&rx_message->data.allow_deny.ip, &ip);
+  subnet_bits = ntohl(rx_message->data.allow_deny.subnet_bits);
+  if (!CAM_AddAccessRestriction(&ip, subnet_bits, allow, all))
+    tx_message->status = htons(STT_BADSUBNET);
+}
+
+/* ================================================== */
+
+static void
+handle_accheck(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr ip;
+  UTI_IPNetworkToHost(&rx_message->data.ac_check.ip, &ip);
+  if (NCR_CheckAccessRestriction(&ip)) {
+    tx_message->status = htons(STT_ACCESSALLOWED);
+  } else {
+    tx_message->status = htons(STT_ACCESSDENIED);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_cmdaccheck(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr ip;
+  UTI_IPNetworkToHost(&rx_message->data.ac_check.ip, &ip);
+  if (CAM_CheckAccessRestriction(&ip)) {
+    tx_message->status = htons(STT_ACCESSALLOWED);
+  } else {
+    tx_message->status = htons(STT_ACCESSDENIED);
+  }
+}
+
+/* ================================================== */
+
+static int
+convert_addsrc_select_options(int flags)
+{
+    return (flags & REQ_ADDSRC_PREFER ? SRC_SELECT_PREFER : 0) |
+           (flags & REQ_ADDSRC_NOSELECT ? SRC_SELECT_NOSELECT : 0) |
+           (flags & REQ_ADDSRC_TRUST ? SRC_SELECT_TRUST : 0) |
+           (flags & REQ_ADDSRC_REQUIRE ? SRC_SELECT_REQUIRE : 0);
+}
+
+/* ================================================== */
+
+static void
+handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NTP_Source_Type type;
+  SourceParameters params;
+  NSR_Status status;
+  char *name;
+  int pool, port;
+  
+  switch (ntohl(rx_message->data.ntp_source.type)) {
+    case REQ_ADDSRC_SERVER:
+      type = NTP_SERVER;
+      pool = 0;
+      break;
+    case REQ_ADDSRC_PEER:
+      type = NTP_PEER;
+      pool = 0;
+      break;
+    case REQ_ADDSRC_POOL:
+      type = NTP_SERVER;
+      pool = 1;
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      return;
+  }
+
+  name = (char *)rx_message->data.ntp_source.name;
+
+  /* Make sure the name is terminated */
+  if (name[sizeof (rx_message->data.ntp_source.name) - 1] != '\0') {
+      tx_message->status = htons(STT_INVALIDNAME);
+      return;
+  }
+
+  port = ntohl(rx_message->data.ntp_source.port);
+  params.minpoll = ntohl(rx_message->data.ntp_source.minpoll);
+  params.maxpoll = ntohl(rx_message->data.ntp_source.maxpoll);
+  params.presend_minpoll = ntohl(rx_message->data.ntp_source.presend_minpoll);
+  params.min_stratum = ntohl(rx_message->data.ntp_source.min_stratum);
+  params.poll_target = ntohl(rx_message->data.ntp_source.poll_target);
+  params.version = ntohl(rx_message->data.ntp_source.version);
+  params.max_sources = ntohl(rx_message->data.ntp_source.max_sources);
+  params.min_samples = ntohl(rx_message->data.ntp_source.min_samples);
+  params.max_samples = ntohl(rx_message->data.ntp_source.max_samples);
+  params.filter_length = ntohl(rx_message->data.ntp_source.filter_length);
+  params.authkey = ntohl(rx_message->data.ntp_source.authkey);
+  params.nts_port = ntohl(rx_message->data.ntp_source.nts_port);
+  params.cert_set = ntohl(rx_message->data.ntp_source.cert_set);
+  params.max_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay);
+  params.max_delay_ratio =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_ratio);
+  params.max_delay_dev_ratio =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_dev_ratio);
+  params.max_delay_quant =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_quant);
+  params.min_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.min_delay);
+  params.asymmetry = UTI_FloatNetworkToHost(rx_message->data.ntp_source.asymmetry);
+  params.offset = UTI_FloatNetworkToHost(rx_message->data.ntp_source.offset);
+
+  params.connectivity = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_ONLINE ?
+                        SRC_ONLINE : SRC_OFFLINE;
+  params.auto_offline = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_AUTOOFFLINE ? 1 : 0;
+  params.iburst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_IBURST ? 1 : 0;
+  params.interleaved = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_INTERLEAVED ? 1 : 0;
+  params.burst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_BURST ? 1 : 0;
+  params.nts = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NTS ? 1 : 0;
+  params.copy = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_COPY ? 1 : 0;
+  params.ext_fields =
+    ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_EF_EXP1 ? NTP_EF_FLAG_EXP1 : 0;
+  params.sel_options = convert_addsrc_select_options(ntohl(rx_message->data.ntp_source.flags));
+
+  status = NSR_AddSourceByName(name, port, pool, type, &params, NULL);
+  switch (status) {
+    case NSR_Success:
+      break;
+    case NSR_UnresolvedName:
+      /* Try to resolve the name now */
+      NSR_ResolveSources();
+      break;
+    case NSR_AlreadyInUse:
+      tx_message->status = htons(STT_SOURCEALREADYKNOWN);
+      break;
+    case NSR_TooManySources:
+      tx_message->status = htons(STT_TOOMANYSOURCES);
+      break;
+    case NSR_InvalidName:
+      tx_message->status = htons(STT_INVALIDNAME);
+      break;
+    case NSR_InvalidAF:
+    case NSR_NoSuchSource:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_del_source(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NSR_Status status;
+  IPAddr ip_addr;
+  
+  UTI_IPNetworkToHost(&rx_message->data.del_source.ip_addr, &ip_addr);
+  
+  status = NSR_RemoveSource(&ip_addr);
+  switch (status) {
+    case NSR_Success:
+      break;
+    case NSR_NoSuchSource:
+      tx_message->status = htons(STT_NOSUCHSOURCE);
+      break;
+    case NSR_TooManySources:
+    case NSR_AlreadyInUse:
+    case NSR_InvalidAF:
+    case NSR_InvalidName:
+    case NSR_UnresolvedName:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_writertc(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  switch (RTC_WriteParameters()) {
+    case RTC_ST_OK:
+      break;
+    case RTC_ST_NODRV:
+      tx_message->status = htons(STT_NORTC);
+      break;
+    case RTC_ST_BADFILE:
+      tx_message->status = htons(STT_BADRTCFILE);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_dfreq(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double dfreq;
+  dfreq = UTI_FloatNetworkToHost(rx_message->data.dfreq.dfreq);
+  LCL_AccumulateDeltaFrequency(dfreq * 1.0e-6);
+  LOG(LOGS_INFO, "Accumulated delta freq of %.3fppm", dfreq);
+}
+
+/* ================================================== */
+
+static void
+handle_doffset(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double doffset;
+
+  doffset = UTI_FloatNetworkToHost(rx_message->data.doffset.doffset);
+  if (!LCL_AccumulateOffset(doffset, 0.0)) {
+    tx_message->status = htons(STT_FAILED);
+  } else {
+    LOG(LOGS_INFO, "Accumulated delta offset of %.6f seconds", doffset);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_tracking(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_TrackingReport rpt;
+
+  REF_GetTrackingReport(&rpt);
+  tx_message->reply  = htons(RPY_TRACKING);
+  tx_message->data.tracking.ref_id = htonl(rpt.ref_id);
+  UTI_IPHostToNetwork(&rpt.ip_addr, &tx_message->data.tracking.ip_addr);
+  tx_message->data.tracking.stratum = htons(rpt.stratum);
+  tx_message->data.tracking.leap_status = htons(rpt.leap_status);
+  UTI_TimespecHostToNetwork(&rpt.ref_time, &tx_message->data.tracking.ref_time);
+  tx_message->data.tracking.current_correction = UTI_FloatHostToNetwork(rpt.current_correction);
+  tx_message->data.tracking.last_offset = UTI_FloatHostToNetwork(rpt.last_offset);
+  tx_message->data.tracking.rms_offset = UTI_FloatHostToNetwork(rpt.rms_offset);
+  tx_message->data.tracking.freq_ppm = UTI_FloatHostToNetwork(rpt.freq_ppm);
+  tx_message->data.tracking.resid_freq_ppm = UTI_FloatHostToNetwork(rpt.resid_freq_ppm);
+  tx_message->data.tracking.skew_ppm = UTI_FloatHostToNetwork(rpt.skew_ppm);
+  tx_message->data.tracking.root_delay = UTI_FloatHostToNetwork(rpt.root_delay);
+  tx_message->data.tracking.root_dispersion = UTI_FloatHostToNetwork(rpt.root_dispersion);
+  tx_message->data.tracking.last_update_interval = UTI_FloatHostToNetwork(rpt.last_update_interval);
+}
+
+/* ================================================== */
+
+static void
+handle_smoothing(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SmoothingReport report;
+  struct timespec now;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  if (!SMT_GetSmoothingReport(&report, &now)) {
+    tx_message->status = htons(STT_NOTENABLED);
+    return;
+  }
+
+  tx_message->reply  = htons(RPY_SMOOTHING);
+  tx_message->data.smoothing.flags = htonl((report.active ? RPY_SMT_FLAG_ACTIVE : 0) |
+                                           (report.leap_only ? RPY_SMT_FLAG_LEAPONLY : 0));
+  tx_message->data.smoothing.offset = UTI_FloatHostToNetwork(report.offset);
+  tx_message->data.smoothing.freq_ppm = UTI_FloatHostToNetwork(report.freq_ppm);
+  tx_message->data.smoothing.wander_ppm = UTI_FloatHostToNetwork(report.wander_ppm);
+  tx_message->data.smoothing.last_update_ago = UTI_FloatHostToNetwork(report.last_update_ago);
+  tx_message->data.smoothing.remaining_time = UTI_FloatHostToNetwork(report.remaining_time);
+}
+
+/* ================================================== */
+
+static void
+handle_smoothtime(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec now;
+  int option;
+
+  if (!SMT_IsEnabled()) {
+    tx_message->status = htons(STT_NOTENABLED);
+    return;
+  }
+
+  option = ntohl(rx_message->data.smoothtime.option);
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  switch (option) {
+    case REQ_SMOOTHTIME_RESET:
+      SMT_Reset(&now);
+      break;
+    case REQ_SMOOTHTIME_ACTIVATE:
+      SMT_Activate(&now);
+      break;
+    default:
+      tx_message->status = htons(STT_INVALID);
+      break;
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_sourcestats(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int status;
+  RPT_SourcestatsReport report;
+  struct timespec now_corr;
+
+  SCH_GetLastEventTime(&now_corr, NULL, NULL);
+  status = SRC_ReportSourcestats(ntohl(rx_message->data.sourcestats.index),
+                                 &report, &now_corr);
+
+  if (status) {
+    tx_message->reply = htons(RPY_SOURCESTATS);
+    tx_message->data.sourcestats.ref_id = htonl(report.ref_id);
+    UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.sourcestats.ip_addr);
+    tx_message->data.sourcestats.n_samples = htonl(report.n_samples);
+    tx_message->data.sourcestats.n_runs = htonl(report.n_runs);
+    tx_message->data.sourcestats.span_seconds = htonl(report.span_seconds);
+    tx_message->data.sourcestats.resid_freq_ppm = UTI_FloatHostToNetwork(report.resid_freq_ppm);
+    tx_message->data.sourcestats.skew_ppm = UTI_FloatHostToNetwork(report.skew_ppm);
+    tx_message->data.sourcestats.sd = UTI_FloatHostToNetwork(report.sd);
+    tx_message->data.sourcestats.est_offset = UTI_FloatHostToNetwork(report.est_offset);
+    tx_message->data.sourcestats.est_offset_err = UTI_FloatHostToNetwork(report.est_offset_err);
+  } else {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_rtcreport(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int status;
+  RPT_RTC_Report report;
+  status = RTC_GetReport(&report);
+  if (status) {
+    tx_message->reply  = htons(RPY_RTC);
+    UTI_TimespecHostToNetwork(&report.ref_time, &tx_message->data.rtc.ref_time);
+    tx_message->data.rtc.n_samples = htons(report.n_samples);
+    tx_message->data.rtc.n_runs = htons(report.n_runs);
+    tx_message->data.rtc.span_seconds = htonl(report.span_seconds);
+    tx_message->data.rtc.rtc_seconds_fast = UTI_FloatHostToNetwork(report.rtc_seconds_fast);
+    tx_message->data.rtc.rtc_gain_rate_ppm = UTI_FloatHostToNetwork(report.rtc_gain_rate_ppm);
+  } else {
+    tx_message->status = htons(STT_NORTC);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_trimrtc(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (!RTC_Trim())
+    tx_message->status = htons(STT_NORTC);
+}
+
+/* ================================================== */
+
+static void
+handle_cyclelogs(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  LOG_CycleLogFiles();
+}
+
+/* ================================================== */
+
+static void
+handle_client_accesses_by_index(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ClientAccessByIndex_Report report;
+  RPY_ClientAccesses_Client *client;
+  int n_indices;
+  uint32_t i, j, req_first_index, req_n_clients, req_min_hits, req_reset;
+  struct timespec now;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  req_first_index = ntohl(rx_message->data.client_accesses_by_index.first_index);
+  req_n_clients = ntohl(rx_message->data.client_accesses_by_index.n_clients);
+  if (req_n_clients > MAX_CLIENT_ACCESSES)
+    req_n_clients = MAX_CLIENT_ACCESSES;
+  req_min_hits = ntohl(rx_message->data.client_accesses_by_index.min_hits);
+  req_reset = ntohl(rx_message->data.client_accesses_by_index.reset);
+
+  n_indices = CLG_GetNumberOfIndices();
+  if (n_indices < 0) {
+    tx_message->status = htons(STT_INACTIVE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_CLIENT_ACCESSES_BY_INDEX3);
+  tx_message->data.client_accesses_by_index.n_indices = htonl(n_indices);
+
+  for (i = req_first_index, j = 0; i < (uint32_t)n_indices && j < req_n_clients; i++) {
+    if (!CLG_GetClientAccessReportByIndex(i, req_reset, req_min_hits, &report, &now))
+      continue;
+
+    client = &tx_message->data.client_accesses_by_index.clients[j++];
+
+    UTI_IPHostToNetwork(&report.ip_addr, &client->ip);
+    client->ntp_hits = htonl(report.ntp_hits);
+    client->nke_hits = htonl(report.nke_hits);
+    client->cmd_hits = htonl(report.cmd_hits);
+    client->ntp_drops = htonl(report.ntp_drops);
+    client->nke_drops = htonl(report.nke_drops);
+    client->cmd_drops = htonl(report.cmd_drops);
+    client->ntp_interval = report.ntp_interval;
+    client->nke_interval = report.nke_interval;
+    client->cmd_interval = report.cmd_interval;
+    client->ntp_timeout_interval = report.ntp_timeout_interval;
+    client->last_ntp_hit_ago = htonl(report.last_ntp_hit_ago);
+    client->last_nke_hit_ago = htonl(report.last_nke_hit_ago);
+    client->last_cmd_hit_ago = htonl(report.last_cmd_hit_ago);
+  }
+
+  tx_message->data.client_accesses_by_index.next_index = htonl(i);
+  tx_message->data.client_accesses_by_index.n_clients = htonl(j);
+}
+
+/* ================================================== */
+
+static void
+handle_manual_list(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int n_samples;
+  int i;
+  RPY_ManualListSample *sample;
+  RPT_ManualSamplesReport report[MAX_MANUAL_LIST_SAMPLES];
+
+  tx_message->reply = htons(RPY_MANUAL_LIST2);
+  
+  MNL_ReportSamples(report, MAX_MANUAL_LIST_SAMPLES, &n_samples);
+  tx_message->data.manual_list.n_samples = htonl(n_samples);
+
+  for (i=0; i<n_samples; i++) {
+    sample = &tx_message->data.manual_list.samples[i];
+    UTI_TimespecHostToNetwork(&report[i].when, &sample->when);
+    sample->slewed_offset = UTI_FloatHostToNetwork(report[i].slewed_offset);
+    sample->orig_offset = UTI_FloatHostToNetwork(report[i].orig_offset);
+    sample->residual = UTI_FloatHostToNetwork(report[i].residual);
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_manual_delete(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int index;
+
+  index = ntohl(rx_message->data.manual_delete.index);
+  if (!MNL_DeleteSample(index))
+    tx_message->status = htons(STT_BADSAMPLE);
+}  
+
+/* ================================================== */
+
+static void
+handle_make_step(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  if (!LCL_MakeStep())
+    tx_message->status = htons(STT_FAILED);
+}
+
+/* ================================================== */
+
+static void
+handle_activity(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ActivityReport report;
+  NSR_GetActivityReport(&report);
+  tx_message->data.activity.online = htonl(report.online);
+  tx_message->data.activity.offline = htonl(report.offline);
+  tx_message->data.activity.burst_online = htonl(report.burst_online);
+  tx_message->data.activity.burst_offline = htonl(report.burst_offline);
+  tx_message->data.activity.unresolved = htonl(report.unresolved);
+  tx_message->reply = htons(RPY_ACTIVITY);
+}
+
+/* ================================================== */
+
+static void
+handle_reselect_distance(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  double dist;
+  dist = UTI_FloatNetworkToHost(rx_message->data.reselect_distance.distance);
+  SRC_SetReselectDistance(dist);
+}
+
+/* ================================================== */
+
+static void
+handle_reselect(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  SRC_ReselectSource();
+}
+
+/* ================================================== */
+
+static void
+handle_refresh(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  NSR_RefreshAddresses();
+}
+
+/* ================================================== */
+
+static void
+handle_server_stats(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_ServerStatsReport report;
+
+  CLG_GetServerStatsReport(&report);
+  tx_message->reply = htons(RPY_SERVER_STATS4);
+  tx_message->data.server_stats.ntp_hits = UTI_Integer64HostToNetwork(report.ntp_hits);
+  tx_message->data.server_stats.nke_hits = UTI_Integer64HostToNetwork(report.nke_hits);
+  tx_message->data.server_stats.cmd_hits = UTI_Integer64HostToNetwork(report.cmd_hits);
+  tx_message->data.server_stats.ntp_drops = UTI_Integer64HostToNetwork(report.ntp_drops);
+  tx_message->data.server_stats.nke_drops = UTI_Integer64HostToNetwork(report.nke_drops);
+  tx_message->data.server_stats.cmd_drops = UTI_Integer64HostToNetwork(report.cmd_drops);
+  tx_message->data.server_stats.log_drops = UTI_Integer64HostToNetwork(report.log_drops);
+  tx_message->data.server_stats.ntp_auth_hits =
+    UTI_Integer64HostToNetwork(report.ntp_auth_hits);
+  tx_message->data.server_stats.ntp_interleaved_hits =
+    UTI_Integer64HostToNetwork(report.ntp_interleaved_hits);
+  tx_message->data.server_stats.ntp_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_timestamps);
+  tx_message->data.server_stats.ntp_span_seconds =
+    UTI_Integer64HostToNetwork(report.ntp_span_seconds);
+  tx_message->data.server_stats.ntp_daemon_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_daemon_rx_timestamps);
+  tx_message->data.server_stats.ntp_daemon_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_daemon_tx_timestamps);
+  tx_message->data.server_stats.ntp_kernel_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_kernel_rx_timestamps);
+  tx_message->data.server_stats.ntp_kernel_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_kernel_tx_timestamps);
+  tx_message->data.server_stats.ntp_hw_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_hw_rx_timestamps);
+  tx_message->data.server_stats.ntp_hw_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_hw_tx_timestamps);
+  memset(tx_message->data.server_stats.reserved, 0xff,
+         sizeof (tx_message->data.server_stats.reserved));
+}
+
+/* ================================================== */
+
+static void
+handle_ntp_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_NTPReport report;
+
+  UTI_IPNetworkToHost(&rx_message->data.ntp_data.ip_addr, &report.remote_addr);
+
+  if (!NSR_GetNTPReport(&report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_NTP_DATA);
+  UTI_IPHostToNetwork(&report.remote_addr, &tx_message->data.ntp_data.remote_addr);
+  UTI_IPHostToNetwork(&report.local_addr, &tx_message->data.ntp_data.local_addr);
+  tx_message->data.ntp_data.remote_port = htons(report.remote_port);
+  tx_message->data.ntp_data.leap = report.leap;
+  tx_message->data.ntp_data.version = report.version;
+  tx_message->data.ntp_data.mode = report.mode;
+  tx_message->data.ntp_data.stratum = report.stratum;
+  tx_message->data.ntp_data.poll = report.poll;
+  tx_message->data.ntp_data.precision = report.precision;
+  tx_message->data.ntp_data.root_delay = UTI_FloatHostToNetwork(report.root_delay);
+  tx_message->data.ntp_data.root_dispersion = UTI_FloatHostToNetwork(report.root_dispersion);
+  tx_message->data.ntp_data.ref_id = htonl(report.ref_id);
+  UTI_TimespecHostToNetwork(&report.ref_time, &tx_message->data.ntp_data.ref_time);
+  tx_message->data.ntp_data.offset = UTI_FloatHostToNetwork(report.offset);
+  tx_message->data.ntp_data.peer_delay = UTI_FloatHostToNetwork(report.peer_delay);
+  tx_message->data.ntp_data.peer_dispersion = UTI_FloatHostToNetwork(report.peer_dispersion);
+  tx_message->data.ntp_data.response_time = UTI_FloatHostToNetwork(report.response_time);
+  tx_message->data.ntp_data.jitter_asymmetry = UTI_FloatHostToNetwork(report.jitter_asymmetry);
+  tx_message->data.ntp_data.flags = htons((report.tests & RPY_NTP_FLAGS_TESTS) |
+                                          (report.interleaved ? RPY_NTP_FLAG_INTERLEAVED : 0) |
+                                          (report.authenticated ? RPY_NTP_FLAG_AUTHENTICATED : 0));
+  tx_message->data.ntp_data.tx_tss_char = report.tx_tss_char;
+  tx_message->data.ntp_data.rx_tss_char = report.rx_tss_char;
+  tx_message->data.ntp_data.total_tx_count = htonl(report.total_tx_count);
+  tx_message->data.ntp_data.total_rx_count = htonl(report.total_rx_count);
+  tx_message->data.ntp_data.total_valid_count = htonl(report.total_valid_count);
+  tx_message->data.ntp_data.total_good_count = htonl(report.total_good_count);
+  memset(tx_message->data.ntp_data.reserved, 0xff, sizeof (tx_message->data.ntp_data.reserved));
+}
+
+/* ================================================== */
+
+static void
+handle_shutdown(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  LOG(LOGS_INFO, "Received shutdown command");
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+handle_ntp_source_name(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  IPAddr addr;
+  char *name;
+
+  UTI_IPNetworkToHost(&rx_message->data.ntp_source_name.ip_addr, &addr);
+  name = NSR_GetName(&addr);
+
+  if (!name) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_NTP_SOURCE_NAME);
+
+  /* Avoid compiler warning */
+  if (strlen(name) >= sizeof (tx_message->data.ntp_source_name.name))
+    memcpy(tx_message->data.ntp_source_name.name, name,
+           sizeof (tx_message->data.ntp_source_name.name));
+  else
+    strncpy((char *)tx_message->data.ntp_source_name.name, name,
+            sizeof (tx_message->data.ntp_source_name.name));
+}
+
+/* ================================================== */
+
+static void
+handle_reload_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  CNF_ReloadSources();
+}
+
+/* ================================================== */
+
+static void
+handle_reset_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  struct timespec cooked_now, now;
+
+  SRC_ResetSources();
+  SCH_GetLastEventTime(&cooked_now, NULL, &now);
+  LCL_NotifyExternalTimeStep(&now, &cooked_now, 0.0, 0.0);
+}
+
+/* ================================================== */
+
+static void
+handle_auth_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_AuthReport report;
+  IPAddr ip_addr;
+
+  UTI_IPNetworkToHost(&rx_message->data.auth_data.ip_addr, &ip_addr);
+
+  if (!NSR_GetAuthReport(&ip_addr, &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_AUTH_DATA);
+
+  switch (report.mode) {
+    case NTP_AUTH_NONE:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NONE);
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_SYMMETRIC);
+      break;
+    case NTP_AUTH_NTS:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NTS);
+      break;
+    default:
+      break;
+  }
+
+  tx_message->data.auth_data.key_type = htons(report.key_type);
+  tx_message->data.auth_data.key_id = htonl(report.key_id);
+  tx_message->data.auth_data.key_length = htons(report.key_length);
+  tx_message->data.auth_data.ke_attempts = htons(report.ke_attempts);
+  tx_message->data.auth_data.last_ke_ago = htonl(report.last_ke_ago);
+  tx_message->data.auth_data.cookies = htons(report.cookies);
+  tx_message->data.auth_data.cookie_length = htons(report.cookie_length);
+  tx_message->data.auth_data.nak = htons(report.nak);
+}
+
+/* ================================================== */
+
+static uint16_t
+convert_sd_sel_options(int options)
+{
+  return (options & SRC_SELECT_PREFER ? RPY_SD_OPTION_PREFER : 0) |
+         (options & SRC_SELECT_NOSELECT ? RPY_SD_OPTION_NOSELECT : 0) |
+         (options & SRC_SELECT_TRUST ? RPY_SD_OPTION_TRUST : 0) |
+         (options & SRC_SELECT_REQUIRE ? RPY_SD_OPTION_REQUIRE : 0);
+}
+
+/* ================================================== */
+
+static void
+handle_select_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SelectReport report;
+
+  if (!SRC_GetSelectReport(ntohl(rx_message->data.select_data.index), &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_SELECT_DATA);
+
+  tx_message->data.select_data.ref_id = htonl(report.ref_id);
+  UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.select_data.ip_addr);
+  tx_message->data.select_data.state_char = report.state_char;
+  tx_message->data.select_data.authentication = report.authentication;
+  tx_message->data.select_data.leap = report.leap;
+  tx_message->data.select_data.conf_options = htons(convert_sd_sel_options(report.conf_options));
+  tx_message->data.select_data.eff_options = htons(convert_sd_sel_options(report.eff_options));
+  tx_message->data.select_data.last_sample_ago = htonl(report.last_sample_ago);
+  tx_message->data.select_data.score = UTI_FloatHostToNetwork(report.score);
+  tx_message->data.select_data.hi_limit = UTI_FloatHostToNetwork(report.hi_limit);
+  tx_message->data.select_data.lo_limit = UTI_FloatHostToNetwork(report.lo_limit);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_selectopts(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int mask, options;
+  uint32_t ref_id;
+  IPAddr ip_addr;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_select_opts.address, &ip_addr);
+  ref_id = ntohl(rx_message->data.modify_select_opts.ref_id);
+  mask = ntohl(rx_message->data.modify_select_opts.mask);
+  options = convert_addsrc_select_options(ntohl(rx_message->data.modify_select_opts.options));
+
+  if (!SRC_ModifySelectOptions(&ip_addr, ref_id, options, mask))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
+/* ================================================== */
+/* Read a packet and process it */
+
+static void
+read_from_cmd_socket(int sock_fd, int event, void *anything)
+{
+  SCK_Message *sck_message;
+  CMD_Request rx_message;
+  CMD_Reply tx_message;
+  IPAddr loopback_addr, remote_ip;
+  int read_length, expected_length;
+  int localhost, allowed, log_index;
+  uint16_t rx_command;
+  struct timespec now, cooked_now;
+
+  sck_message = SCK_ReceiveMessage(sock_fd, 0);
+  if (!sck_message)
+    return;
+
+  read_length = sck_message->length;
+
+  /* Get current time cheaply */
+  SCH_GetLastEventTime(&cooked_now, NULL, &now);
+
+  /* Check if it's from localhost (127.0.0.1, ::1, or Unix domain),
+     or an authorised address */
+  switch (sck_message->addr_type) {
+    case SCK_ADDR_IP:
+      assert(sock_fd == sock_fd4 || sock_fd == sock_fd6);
+      remote_ip = sck_message->remote_addr.ip.ip_addr;
+      SCK_GetLoopbackIPAddress(remote_ip.family, &loopback_addr);
+      localhost = UTI_CompareIPs(&remote_ip, &loopback_addr, NULL) == 0;
+
+      if (!localhost && !ADF_IsAllowed(access_auth_table, &remote_ip)) {
+        DEBUG_LOG("Unauthorised host %s",
+                  UTI_IPSockAddrToString(&sck_message->remote_addr.ip));
+        return;
+      }
+
+      assert(remote_ip.family != IPADDR_UNSPEC);
+
+      break;
+    case SCK_ADDR_UNIX:
+      assert(sock_fd == sock_fdu);
+      remote_ip.family = IPADDR_UNSPEC;
+      localhost = 1;
+      break;
+    default:
+      DEBUG_LOG("Unexpected address type");
+      return;
+  }
+
+  if (read_length < offsetof(CMD_Request, data) ||
+      read_length < offsetof(CMD_Reply, data) ||
+      read_length > sizeof (CMD_Request)) {
+    /* We don't know how to process anything like this or an error reply
+       would be larger than the request */
+    DEBUG_LOG("Unexpected length");
+    return;
+  }
+
+  memcpy(&rx_message, sck_message->data, read_length);
+
+  if (rx_message.pkt_type != PKT_TYPE_CMD_REQUEST ||
+      rx_message.res1 != 0 ||
+      rx_message.res2 != 0) {
+    DEBUG_LOG("Command packet dropped");
+    return;
+  }
+
+  log_index = CLG_LogServiceAccess(CLG_CMDMON, &remote_ip, &cooked_now);
+
+  /* Don't reply to all requests from hosts other than localhost if the rate
+     is excessive */
+  if (!localhost && log_index >= 0 && CLG_LimitServiceRate(CLG_CMDMON, log_index)) {
+      DEBUG_LOG("Command packet discarded to limit response rate");
+      return;
+  }
+
+  expected_length = PKL_CommandLength(&rx_message);
+  rx_command = ntohs(rx_message.command);
+
+  memset(&tx_message, 0, sizeof (tx_message));
+  sck_message->data = &tx_message;
+  sck_message->length = 0;
+
+  tx_message.version = PROTO_VERSION_NUMBER;
+  tx_message.pkt_type = PKT_TYPE_CMD_REPLY;
+  tx_message.command = rx_message.command;
+  tx_message.reply = htons(RPY_NULL);
+  tx_message.status = htons(STT_SUCCESS);
+  tx_message.sequence = rx_message.sequence;
+
+  if (rx_message.version != PROTO_VERSION_NUMBER) {
+    DEBUG_LOG("Command packet has invalid version (%d != %d)",
+              rx_message.version, PROTO_VERSION_NUMBER);
+
+    if (rx_message.version >= PROTO_VERSION_MISMATCH_COMPAT_SERVER) {
+      tx_message.status = htons(STT_BADPKTVERSION);
+      transmit_reply(sock_fd, read_length, sck_message);
+    }
+    return;
+  }
+
+  if (rx_command >= N_REQUEST_TYPES ||
+      expected_length < (int)offsetof(CMD_Request, data)) {
+    DEBUG_LOG("Command packet has invalid command %d", rx_command);
+
+    tx_message.status = htons(STT_INVALID);
+    transmit_reply(sock_fd, read_length, sck_message);
+    return;
+  }
+
+  if (read_length < expected_length) {
+    DEBUG_LOG("Command packet is too short (%d < %d)", read_length,
+              expected_length);
+
+    tx_message.status = htons(STT_BADPKTLENGTH);
+    transmit_reply(sock_fd, read_length, sck_message);
+    return;
+  }
+
+  /* OK, we have a valid message.  Now dispatch on message type and process it. */
+
+  if (rx_command >= N_REQUEST_TYPES) {
+    /* This should be already handled */
+    assert(0);
+  } else {
+    /* Check level of authority required to issue the command.  All commands
+       from the Unix domain socket (which is accessible only by the root and
+       chrony user/group) are allowed. */
+    if (remote_ip.family == IPADDR_UNSPEC) {
+      assert(sock_fd == sock_fdu);
+      allowed = 1;
+    } else {
+      switch (permissions[rx_command]) {
+        case PERMIT_AUTH:
+          allowed = 0;
+          break;
+        case PERMIT_LOCAL:
+          allowed = localhost;
+          break;
+        case PERMIT_OPEN:
+          allowed = 1;
+          break;
+        default:
+          assert(0);
+          allowed = 0;
+      }
+    }
+
+    if (allowed) {
+      LOG_SetContext(LOGC_Command);
+
+      switch(rx_command) {
+        case REQ_NULL:
+          /* Do nothing */
+          break;
+
+        case REQ_DUMP:
+          handle_dump(&rx_message, &tx_message);
+          break;
+
+        case REQ_ONLINE:
+          handle_online(&rx_message, &tx_message);
+          break;
+
+        case REQ_OFFLINE:
+          handle_offline(&rx_message, &tx_message);
+          break;
+
+        case REQ_BURST:
+          handle_burst(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MINPOLL:
+          handle_modify_minpoll(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXPOLL:
+          handle_modify_maxpoll(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAY:
+          handle_modify_maxdelay(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAYRATIO:
+          handle_modify_maxdelayratio(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXDELAYDEVRATIO:
+          handle_modify_maxdelaydevratio(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAXUPDATESKEW:
+          handle_modify_maxupdateskew(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MAKESTEP:
+          handle_modify_makestep(&rx_message, &tx_message);
+          break;
+
+        case REQ_LOGON:
+          /* Authentication is no longer supported, log-on always fails */
+          tx_message.status = htons(STT_FAILED);
+          break;
+
+        case REQ_SETTIME:
+          handle_settime(&rx_message, &tx_message);
+          break;
+        
+        case REQ_LOCAL2:
+          handle_local(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL:
+          handle_manual(&rx_message, &tx_message);
+          break;
+
+        case REQ_N_SOURCES:
+          handle_n_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_SOURCE_DATA:
+          handle_source_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_REKEY:
+          handle_rekey(&rx_message, &tx_message);
+          break;
+
+        case REQ_ALLOW:
+          handle_allowdeny(&rx_message, &tx_message, 1, 0);
+          break;
+
+        case REQ_ALLOWALL:
+          handle_allowdeny(&rx_message, &tx_message, 1, 1);
+          break;
+
+        case REQ_DENY:
+          handle_allowdeny(&rx_message, &tx_message, 0, 0);
+          break;
+
+        case REQ_DENYALL:
+          handle_allowdeny(&rx_message, &tx_message, 0, 1);
+          break;
+
+        case REQ_CMDALLOW:
+          handle_cmdallowdeny(&rx_message, &tx_message, 1, 0);
+          break;
+
+        case REQ_CMDALLOWALL:
+          handle_cmdallowdeny(&rx_message, &tx_message, 1, 1);
+          break;
+
+        case REQ_CMDDENY:
+          handle_cmdallowdeny(&rx_message, &tx_message, 0, 0);
+          break;
+
+        case REQ_CMDDENYALL:
+          handle_cmdallowdeny(&rx_message, &tx_message, 0, 1);
+          break;
+
+        case REQ_ACCHECK:
+          handle_accheck(&rx_message, &tx_message);
+          break;
+
+        case REQ_CMDACCHECK:
+          handle_cmdaccheck(&rx_message, &tx_message);
+          break;
+
+        case REQ_ADD_SOURCE:
+          handle_add_source(&rx_message, &tx_message);
+          break;
+
+        case REQ_DEL_SOURCE:
+          handle_del_source(&rx_message, &tx_message);
+          break;
+
+        case REQ_WRITERTC:
+          handle_writertc(&rx_message, &tx_message);
+          break;
+          
+        case REQ_DFREQ:
+          handle_dfreq(&rx_message, &tx_message);
+          break;
+
+        case REQ_DOFFSET2:
+          handle_doffset(&rx_message, &tx_message);
+          break;
+
+        case REQ_TRACKING:
+          handle_tracking(&rx_message, &tx_message);
+          break;
+
+        case REQ_SMOOTHING:
+          handle_smoothing(&rx_message, &tx_message);
+          break;
+
+        case REQ_SMOOTHTIME:
+          handle_smoothtime(&rx_message, &tx_message);
+          break;
+
+        case REQ_SOURCESTATS:
+          handle_sourcestats(&rx_message, &tx_message);
+          break;
+
+        case REQ_RTCREPORT:
+          handle_rtcreport(&rx_message, &tx_message);
+          break;
+          
+        case REQ_TRIMRTC:
+          handle_trimrtc(&rx_message, &tx_message);
+          break;
+
+        case REQ_CYCLELOGS:
+          handle_cyclelogs(&rx_message, &tx_message);
+          break;
+
+        case REQ_CLIENT_ACCESSES_BY_INDEX3:
+          handle_client_accesses_by_index(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL_LIST:
+          handle_manual_list(&rx_message, &tx_message);
+          break;
+
+        case REQ_MANUAL_DELETE:
+          handle_manual_delete(&rx_message, &tx_message);
+          break;
+
+        case REQ_MAKESTEP:
+          handle_make_step(&rx_message, &tx_message);
+          break;
+
+        case REQ_ACTIVITY:
+          handle_activity(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESELECTDISTANCE:
+          handle_reselect_distance(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESELECT:
+          handle_reselect(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_MINSTRATUM:
+          handle_modify_minstratum(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_POLLTARGET:
+          handle_modify_polltarget(&rx_message, &tx_message);
+          break;
+
+        case REQ_REFRESH:
+          handle_refresh(&rx_message, &tx_message);
+          break;
+
+        case REQ_SERVER_STATS:
+          handle_server_stats(&rx_message, &tx_message);
+          break;
+
+        case REQ_NTP_DATA:
+          handle_ntp_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_SHUTDOWN:
+          handle_shutdown(&rx_message, &tx_message);
+          break;
+
+        case REQ_ONOFFLINE:
+          handle_onoffline(&rx_message, &tx_message);
+          break;
+
+        case REQ_NTP_SOURCE_NAME:
+          handle_ntp_source_name(&rx_message, &tx_message);
+          break;
+
+        case REQ_RESET_SOURCES:
+          handle_reset_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_AUTH_DATA:
+          handle_auth_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_SELECT_DATA:
+          handle_select_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_RELOAD_SOURCES:
+          handle_reload_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_SELECTOPTS:
+          handle_modify_selectopts(&rx_message, &tx_message);
+          break;
+
+        default:
+          DEBUG_LOG("Unhandled command %d", rx_command);
+          tx_message.status = htons(STT_FAILED);
+          break;
+      }
+
+      LOG_UnsetContext(LOGC_Command);
+    } else {
+      tx_message.status = htons(STT_UNAUTH);
+    }
+  }
+
+  /* Transmit the response */
+  transmit_reply(sock_fd, read_length, sck_message);
+}
+
+/* ================================================== */
+
+int
+CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+ {
+  ADF_Status status;
+
+  if (allow) {
+    if (all) {
+      status = ADF_AllowAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Allow(access_auth_table, ip_addr, subnet_bits);
+    }
+  } else {
+    if (all) {
+      status = ADF_DenyAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Deny(access_auth_table, ip_addr, subnet_bits);
+    }
+  }
+
+  if (status == ADF_BADSUBNET) {
+    return 0;
+  } else if (status == ADF_SUCCESS) {
+    LOG(LOG_GetContextSeverity(LOGC_Command), "%s%s %s access from %s",
+        allow ? "Allowed" : "Denied", all ? " all" : "", "command",
+        UTI_IPSubnetToString(ip_addr, subnet_bits));
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+CAM_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return ADF_IsAllowed(access_auth_table, ip_addr);
+}
+
+
+/* ================================================== */
+/* ================================================== */
diff --git a/cmdmon.h b/cmdmon.h
new file mode 100644
index 0000000..86356b9
--- /dev/null
+++ b/cmdmon.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the control and monitoring module in the software
+  */
+
+#ifndef GOT_CMDMON_H
+#define GOT_CMDMON_H
+
+#include "addressing.h"
+
+extern void CAM_Initialise(void);
+
+extern void CAM_Finalise(void);
+
+extern void CAM_OpenUnixSocket(void);
+extern int CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all);
+extern int CAM_CheckAccessRestriction(IPAddr *ip_addr);
+
+#endif /* GOT_CMDMON_H */
diff --git a/cmdparse.c b/cmdparse.c
new file mode 100644
index 0000000..c20e8a3
--- /dev/null
+++ b/cmdparse.c
@@ -0,0 +1,425 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2013-2014, 2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+  
+  Module for parsing various forms of directive and command lines that
+  are common to the configuration file and to the command client.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "cmdparse.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "ntp.h"
+#include "util.h"
+
+/* ================================================== */
+
+int
+CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
+{
+  char *hostname, *cmd;
+  uint32_t ef_type;
+  int n, sel_option;
+  
+  src->port = SRC_DEFAULT_PORT;
+  src->params.minpoll = SRC_DEFAULT_MINPOLL;
+  src->params.maxpoll = SRC_DEFAULT_MAXPOLL;
+  src->params.connectivity = SRC_ONLINE;
+  src->params.auto_offline = 0;
+  src->params.presend_minpoll = SRC_DEFAULT_PRESEND_MINPOLL;
+  src->params.burst = 0;
+  src->params.iburst = 0;
+  src->params.min_stratum = SRC_DEFAULT_MINSTRATUM;
+  src->params.poll_target = SRC_DEFAULT_POLLTARGET;
+  src->params.version = 0;
+  src->params.max_sources = SRC_DEFAULT_MAXSOURCES;
+  src->params.min_samples = SRC_DEFAULT_MINSAMPLES;
+  src->params.max_samples = SRC_DEFAULT_MAXSAMPLES;
+  src->params.filter_length = 0;
+  src->params.interleaved = 0;
+  src->params.sel_options = 0;
+  src->params.nts = 0;
+  src->params.nts_port = SRC_DEFAULT_NTSPORT;
+  src->params.copy = 0;
+  src->params.ext_fields = 0;
+  src->params.authkey = INACTIVE_AUTHKEY;
+  src->params.cert_set = SRC_DEFAULT_CERTSET;
+  src->params.max_delay = SRC_DEFAULT_MAXDELAY;
+  src->params.max_delay_ratio = SRC_DEFAULT_MAXDELAYRATIO;
+  src->params.max_delay_dev_ratio = SRC_DEFAULT_MAXDELAYDEVRATIO;
+  src->params.max_delay_quant = 0.0;
+  src->params.min_delay = 0.0;
+  src->params.asymmetry = SRC_DEFAULT_ASYMMETRY;
+  src->params.offset = 0.0;
+
+  hostname = line;
+  line = CPS_SplitWord(line);
+
+  if (!*hostname)
+    return 0;
+
+  src->name = hostname;
+
+  /* Parse options */
+  for (; *line; line += n) {
+    cmd = line;
+    line = CPS_SplitWord(line);
+    n = 0;
+
+    if (!strcasecmp(cmd, "auto_offline")) {
+      src->params.auto_offline = 1;
+    } else if (!strcasecmp(cmd, "burst")) {
+      src->params.burst = 1;
+    } else if (!strcasecmp(cmd, "copy")) {
+      src->params.copy = 1;
+    } else if (!strcasecmp(cmd, "iburst")) {
+      src->params.iburst = 1;
+    } else if (!strcasecmp(cmd, "offline")) {
+      src->params.connectivity = SRC_OFFLINE;
+    } else if (!strcasecmp(cmd, "certset")) {
+      if (sscanf(line, "%"SCNu32"%n", &src->params.cert_set, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "key")) {
+      if (sscanf(line, "%"SCNu32"%n", &src->params.authkey, &n) != 1 ||
+          src->params.authkey == INACTIVE_AUTHKEY)
+        return 0;
+    } else if (!strcasecmp(cmd, "asymmetry")) {
+      if (sscanf(line, "%lf%n", &src->params.asymmetry, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "extfield")) {
+      if (sscanf(line, "%"SCNx32"%n", &ef_type, &n) != 1)
+        return 0;
+      switch (ef_type) {
+        case NTP_EF_EXP1:
+          src->params.ext_fields |= NTP_EF_FLAG_EXP1;
+          break;
+        default:
+          return 0;
+      }
+    } else if (!strcasecmp(cmd, "filter")) {
+      if (sscanf(line, "%d%n", &src->params.filter_length, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelay")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelayratio")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_ratio, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelaydevratio")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_dev_ratio, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxdelayquant")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_quant, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxpoll")) {
+      if (sscanf(line, "%d%n", &src->params.maxpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxsamples")) {
+      if (sscanf(line, "%d%n", &src->params.max_samples, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "maxsources")) {
+      if (sscanf(line, "%d%n", &src->params.max_sources, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "mindelay")) {
+      if (sscanf(line, "%lf%n", &src->params.min_delay, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minpoll")) {
+      if (sscanf(line, "%d%n", &src->params.minpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minsamples")) {
+      if (sscanf(line, "%d%n", &src->params.min_samples, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "minstratum")) {
+      if (sscanf(line, "%d%n", &src->params.min_stratum, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "nts")) {
+      src->params.nts = 1;
+    } else if (!strcasecmp(cmd, "ntsport")) {
+      if (sscanf(line, "%d%n", &src->params.nts_port, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "offset")) {
+      if (sscanf(line, "%lf%n", &src->params.offset, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "port")) {
+      if (sscanf(line, "%d%n", &src->port, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "polltarget")) {
+      if (sscanf(line, "%d%n", &src->params.poll_target, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "presend")) {
+      if (sscanf(line, "%d%n", &src->params.presend_minpoll, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "version")) {
+      if (sscanf(line, "%d%n", &src->params.version, &n) != 1)
+        return 0;
+    } else if (!strcasecmp(cmd, "xleave")) {
+      src->params.interleaved = 1;
+    } else if ((sel_option = CPS_GetSelectOption(cmd)) != 0) {
+      src->params.sel_options |= sel_option;
+    } else {
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+CPS_GetSelectOption(char *option)
+{
+  if (!strcasecmp(option, "noselect")) {
+    return SRC_SELECT_NOSELECT;
+  } else if (!strcasecmp(option, "prefer")) {
+    return SRC_SELECT_PREFER;
+  } else if (!strcasecmp(option, "require")) {
+    return SRC_SELECT_REQUIRE;
+  } else if (!strcasecmp(option, "trust")) {
+    return SRC_SELECT_TRUST;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits)
+{
+  char *p, *net, *slash;
+  uint32_t a, b, c;
+  int bits, len, n;
+
+  p = CPS_SplitWord(line);
+
+  if (strcmp(line, "all") == 0) {
+    *all = 1;
+    net = p;
+    p = CPS_SplitWord(p);
+  } else {
+    *all = 0;
+    net = line;
+  }
+
+  /* Make sure there are no other arguments */
+  if (*p)
+    return 0;
+
+  /* No specified address or network means all IPv4 and IPv6 addresses */
+  if (!*net) {
+    ip->family = IPADDR_UNSPEC;
+    *subnet_bits = 0;
+    return 1;
+  }
+
+  slash = strchr(net, '/');
+  if (slash) {
+    if (sscanf(slash + 1, "%d%n", &bits, &len) != 1 || slash[len + 1] || bits < 0)
+      return 0;
+    *slash = '\0';
+  } else {
+    bits = -1;
+  }
+
+  if (UTI_StringToIP(net, ip)) {
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  /* Check for a shortened IPv4 network notation using only 1, 2, or 3 decimal
+     numbers.  This is different than the numbers-and-dots notation accepted
+     by inet_aton()! */
+
+  a = b = c = 0;
+  n = sscanf(net, "%"PRIu32"%n.%"PRIu32"%n.%"PRIu32"%n", &a, &len, &b, &len, &c, &len);
+
+  if (n > 0 && !net[len]) {
+    if (a > 255 || b > 255 || c > 255)
+      return 0;
+
+    ip->family = IPADDR_INET4;
+    ip->addr.in4 = (a << 24) | (b << 16) | (c << 8);
+
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = n * 8;
+
+    return 1;
+  }
+
+  /* The last possibility is a hostname */
+  if (bits < 0 && DNS_Name2IPAddress(net, ip, 1) == DNS_Success) {
+    *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance)
+{
+  int n;
+  char *cmd;
+
+  *stratum = 10;
+  *distance = 1.0;
+  *orphan = 0;
+
+  while (*line) {
+    cmd = line;
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(cmd, "stratum")) {
+      if (sscanf(line, "%d%n", stratum, &n) != 1 ||
+          *stratum >= NTP_MAX_STRATUM || *stratum <= 0)
+        return 0;
+    } else if (!strcasecmp(cmd, "orphan")) {
+      *orphan = 1;
+      n = 0;
+    } else if (!strcasecmp(cmd, "distance")) {
+      if (sscanf(line, "%lf%n", distance, &n) != 1)
+        return 0;
+    } else {
+      return 0;
+    }
+
+    line += n;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CPS_NormalizeLine(char *line)
+{
+  char *p, *q;
+  int space = 1, first = 1;
+
+  /* Remove white-space at beginning and replace white-spaces with space char */
+  for (p = q = line; *p; p++) {
+    if (isspace((unsigned char)*p)) {
+      if (!space)
+        *q++ = ' ';
+      space = 1;
+      continue;
+    }
+
+    /* Discard comment lines */
+    if (first && strchr("!;#%", *p))
+      break;
+
+    *q++ = *p;
+    space = first = 0;
+  }
+
+  /* Strip trailing space */
+  if (q > line && q[-1] == ' ')
+    q--;
+
+  *q = '\0';
+}
+
+/* ================================================== */
+
+char *
+CPS_SplitWord(char *line)
+{
+  char *p = line, *q = line;
+
+  /* Skip white-space before the word */
+  while (*q && isspace((unsigned char)*q))
+    q++;
+
+  /* Move the word to the beginning */
+  while (*q && !isspace((unsigned char)*q))
+    *p++ = *q++;
+
+  /* Find the next word */
+  while (*q && isspace((unsigned char)*q))
+    q++;
+
+  *p = '\0';
+
+  /* Return pointer to the next word or NUL */
+  return q;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key)
+{
+  char *s1, *s2, *s3, *s4;
+
+  s1 = line;
+  s2 = CPS_SplitWord(s1);
+  s3 = CPS_SplitWord(s2);
+  s4 = CPS_SplitWord(s3);
+
+  /* Require two or three words */
+  if (!*s2 || *s4)
+    return 0;
+
+  if (sscanf(s1, "%"SCNu32, id) != 1)
+    return 0;
+
+  if (*s3) {
+    *type = s2;
+    *key = s3;
+  } else {
+    *type = "MD5";
+    *key = s2;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseRefid(char *line, uint32_t *ref_id)
+{
+  int i;
+
+  for (i = *ref_id = 0; line[i] && !isspace((unsigned char)line[i]); i++) {
+    if (i >= 4)
+      return 0;
+    *ref_id |= (uint32_t)line[i] << (24 - i * 8);
+  }
+
+  return i;
+}
diff --git a/cmdparse.h b/cmdparse.h
new file mode 100644
index 0000000..7a87979
--- /dev/null
+++ b/cmdparse.h
@@ -0,0 +1,63 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the command parser
+  */
+
+#ifndef GOT_CMDPARSE_H
+#define GOT_CMDPARSE_H
+
+#include "srcparams.h"
+#include "addressing.h"
+
+typedef struct {
+  char *name;
+  int port;
+  SourceParameters params;
+} CPS_NTP_Source;
+
+/* Parse a command to add an NTP server or peer */
+extern int CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src);
+  
+/* Get an NTP/refclock select option */
+extern int CPS_GetSelectOption(char *option);
+
+/* Parse a command to allow/deny access */
+extern int CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits);
+
+/* Parse a command to enable local reference */
+extern int CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance);
+
+/* Remove extra white-space and comments */
+extern void CPS_NormalizeLine(char *line);
+
+/* Terminate first word and return pointer to the next word */
+extern char *CPS_SplitWord(char *line);
+
+/* Parse a key from keyfile */
+extern int CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key);
+
+/* Parse a refclock reference ID (returns number of characters) */
+extern int CPS_ParseRefid(char *line, uint32_t *ref_id);
+
+#endif /* GOT_CMDPARSE_H */
diff --git a/conf.c b/conf.c
new file mode 100644
index 0000000..f984060
--- /dev/null
+++ b/conf.c
@@ -0,0 +1,2645 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2017, 2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module that reads and processes the configuration file.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "conf.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "nts_ke.h"
+#include "refclock.h"
+#include "cmdmon.h"
+#include "socket.h"
+#include "srcparams.h"
+#include "logging.h"
+#include "nameserv.h"
+#include "memory.h"
+#include "cmdparse.h"
+#include "util.h"
+
+/* ================================================== */
+
+#define MAX_LINE_LENGTH 2048
+#define MAX_CONF_DIRS 10
+#define MAX_INCLUDE_LEVEL 10
+
+/* ================================================== */
+/* Forward prototypes */
+
+static int parse_string(char *line, char **result);
+static int parse_int(char *line, int *result);
+static int parse_double(char *line, double *result);
+static int parse_null(char *line);
+
+static void parse_allow_deny(char *line, ARR_Instance restrictions, int allow);
+static void parse_authselectmode(char *);
+static void parse_bindacqaddress(char *);
+static void parse_bindaddress(char *);
+static void parse_bindcmdaddress(char *);
+static void parse_broadcast(char *);
+static void parse_clientloglimit(char *);
+static void parse_confdir(char *);
+static void parse_fallbackdrift(char *);
+static void parse_hwtimestamp(char *);
+static void parse_include(char *);
+static void parse_initstepslew(char *);
+static void parse_leapsecmode(char *);
+static void parse_local(char *);
+static void parse_log(char *);
+static void parse_mailonchange(char *);
+static void parse_makestep(char *);
+static void parse_maxchange(char *);
+static void parse_ntsserver(char *, ARR_Instance files);
+static void parse_ntstrustedcerts(char *);
+static void parse_ratelimit(char *line, int *enabled, int *interval,
+                            int *burst, int *leak);
+static void parse_refclock(char *);
+static void parse_smoothtime(char *);
+static void parse_source(char *line, char *type, int fatal);
+static void parse_sourcedir(char *);
+static void parse_tempcomp(char *);
+
+/* ================================================== */
+/* Configuration variables */
+
+static int print_config = 0;
+static int restarted = 0;
+static char *rtc_device;
+static int acquisition_port = -1;
+static int ntp_port = NTP_PORT;
+static char *keys_file = NULL;
+static char *drift_file = NULL;
+static char *rtc_file = NULL;
+static double max_update_skew = 1000.0;
+static double correction_time_ratio = 3.0;
+static double max_clock_error = 1.0; /* in ppm */
+static double max_drift = 500000.0; /* in ppm */
+static double max_slew_rate = 1e6 / 12.0; /* in ppm */
+static double clock_precision = 0.0; /* in seconds */
+
+static SRC_AuthSelectMode authselect_mode = SRC_AUTHSELECT_MIX;
+static double max_distance = 3.0;
+static double max_jitter = 1.0;
+static double reselect_distance = 1e-4;
+static double stratum_weight = 1e-3;
+static double combine_limit = 3.0;
+
+static int cmd_port = DEFAULT_CANDM_PORT;
+
+static int raw_measurements = 0;
+static int do_log_measurements = 0;
+static int do_log_selection = 0;
+static int do_log_statistics = 0;
+static int do_log_tracking = 0;
+static int do_log_rtc = 0;
+static int do_log_refclocks = 0;
+static int do_log_tempcomp = 0;
+static int log_banner = 32;
+static char *logdir = NULL;
+static char *dumpdir = NULL;
+
+static int enable_local=0;
+static int local_stratum;
+static int local_orphan;
+static double local_distance;
+
+/* Threshold (in seconds) - if absolute value of initial error is less
+   than this, slew instead of stepping */
+static double init_slew_threshold;
+/* Array of IPAddr */
+static ARR_Instance init_sources;
+
+static int enable_manual=0;
+
+/* Flag set if the RTC runs UTC (default is it runs local time
+   incl. daylight saving). */
+static int rtc_on_utc = 0;
+
+/* Filename used to read the hwclock(8) LOCAL/UTC setting */
+static char *hwclock_file;
+
+/* Flag set if the RTC should be automatically synchronised by kernel */
+static int rtc_sync = 0;
+
+/* Limit and threshold for clock stepping */
+static int make_step_limit = 0;
+static double make_step_threshold = 0.0;
+
+/* Threshold for automatic RTC trimming */
+static double rtc_autotrim_threshold = 0.0;
+
+/* Minimum number of selectables sources required to update the clock */
+static int min_sources = 1;
+
+/* Number of updates before offset checking, number of ignored updates
+   before exiting and the maximum allowed offset */
+static int max_offset_delay = -1;
+static int max_offset_ignore;
+static double max_offset;
+
+/* Maximum and minimum number of samples per source */
+static int max_samples = 0; /* no limit */
+static int min_samples = 6;
+
+/* Threshold for a time adjustment to be logged to syslog */
+static double log_change_threshold = 1.0;
+
+static char *mail_user_on_change = NULL;
+static double mail_change_threshold = 0.0;
+
+/* Flag indicating that we don't want to log clients, e.g. to save
+   memory */
+static int no_client_log = 0;
+
+/* Limit memory allocated for the clients log */
+static unsigned long client_log_limit = 524288;
+
+/* Minimum and maximum fallback drift intervals */
+static int fb_drift_min = 0;
+static int fb_drift_max = 0;
+
+/* IP addresses for binding the NTP server sockets to.  UNSPEC family means
+   INADDR_ANY will be used */
+static IPAddr bind_address4, bind_address6;
+
+/* IP addresses for binding the NTP client sockets to.  UNSPEC family means
+   INADDR_ANY will be used */
+static IPAddr bind_acq_address4, bind_acq_address6;
+
+/* IP addresses for binding the command socket to.  UNSPEC family means
+   the loopback address will be used */
+static IPAddr bind_cmd_address4, bind_cmd_address6;
+
+/* Interface names to bind the NTP server, NTP client, and command socket */
+static char *bind_ntp_iface = NULL;
+static char *bind_acq_iface = NULL;
+static char *bind_cmd_iface = NULL;
+
+/* Path to the Unix domain command socket. */
+static char *bind_cmd_path = NULL;
+
+/* Differentiated Services Code Point (DSCP) in transmitted NTP packets */
+static int ntp_dscp = 0;
+
+/* Path to Samba (ntp_signd) socket. */
+static char *ntp_signd_socket = NULL;
+
+/* Filename to use for storing pid of running chronyd, to prevent multiple
+ * chronyds being started. */
+static char *pidfile = NULL;
+
+/* Rate limiting parameters */
+static int ntp_ratelimit_enabled = 0;
+static int ntp_ratelimit_interval = 3;
+static int ntp_ratelimit_burst = 8;
+static int ntp_ratelimit_leak = 2;
+static int nts_ratelimit_enabled = 0;
+static int nts_ratelimit_interval = 6;
+static int nts_ratelimit_burst = 8;
+static int nts_ratelimit_leak = 2;
+static int cmd_ratelimit_enabled = 0;
+static int cmd_ratelimit_interval = -4;
+static int cmd_ratelimit_burst = 8;
+static int cmd_ratelimit_leak = 2;
+
+/* Smoothing constants */
+static double smooth_max_freq = 0.0; /* in ppm */
+static double smooth_max_wander = 0.0; /* in ppm/s */
+static int smooth_leap_only = 0;
+
+/* Temperature sensor, update interval and compensation coefficients */
+static char *tempcomp_sensor_file = NULL;
+static char *tempcomp_point_file = NULL;
+static double tempcomp_interval;
+static double tempcomp_T0, tempcomp_k0, tempcomp_k1, tempcomp_k2;
+
+static int sched_priority = 0;
+static int lock_memory = 0;
+
+/* Leap second handling mode */
+static REF_LeapMode leapsec_mode = REF_LeapModeSystem;
+
+/* Name of a system timezone containing leap seconds occuring at midnight */
+static char *leapsec_tz = NULL;
+
+/* Name of the user to which will be dropped root privileges. */
+static char *user;
+
+/* Address refresh interval */
+static int refresh = 1209600; /* 2 weeks */
+
+/* NTS server and client configuration */
+static char *nts_dump_dir = NULL;
+static char *nts_ntp_server = NULL;
+static ARR_Instance nts_server_cert_files; /* array of (char *) */
+static ARR_Instance nts_server_key_files; /* array of (char *) */
+static int nts_server_port = NKE_PORT;
+static int nts_server_processes = 1;
+static int nts_server_connections = 100;
+static int nts_refresh = 2419200; /* 4 weeks */
+static int nts_rotate = 604800; /* 1 week */
+static ARR_Instance nts_trusted_certs_paths; /* array of (char *) */
+static ARR_Instance nts_trusted_certs_ids; /* array of uint32_t */
+
+/* Number of clock updates needed to enable certificate time checks */
+static int no_cert_time_check = 0;
+
+/* Flag disabling use of system trusted certificates */
+static int no_system_cert = 0;
+
+/* Array of CNF_HwTsInterface */
+static ARR_Instance hwts_interfaces;
+
+/* Timeout for resuming reading from sockets waiting for HW TX timestamp */
+static double hwts_timeout = 0.001;
+
+/* PTP event port (disabled by default) */
+static int ptp_port = 0;
+
+typedef struct {
+  NTP_Source_Type type;
+  int pool;
+  CPS_NTP_Source params;
+} NTP_Source;
+
+/* Array of NTP_Source */
+static ARR_Instance ntp_sources;
+/* Array of (char *) */
+static ARR_Instance ntp_source_dirs;
+/* Array of uint32_t corresponding to ntp_sources (for sourcedirs reload) */
+static ARR_Instance ntp_source_ids;
+
+/* Array of RefclockParameters */
+static ARR_Instance refclock_sources;
+
+typedef struct _AllowDeny {
+  IPAddr ip;
+  int subnet_bits;
+  int all; /* 1 to override existing more specific defns */
+  int allow; /* 0 for deny, 1 for allow */
+} AllowDeny;
+
+/* Arrays of AllowDeny */
+static ARR_Instance ntp_restrictions;
+static ARR_Instance cmd_restrictions;
+
+typedef struct {
+  NTP_Remote_Address addr;
+  int interval;
+} NTP_Broadcast_Destination;
+
+/* Array of NTP_Broadcast_Destination */
+static ARR_Instance broadcasts;
+
+/* ================================================== */
+
+/* The line number in the configuration file being processed */
+static int line_number;
+static const char *processed_file;
+static const char *processed_command;
+
+static int include_level = 0;
+
+/* ================================================== */
+
+static void
+command_parse_error(void)
+{
+    LOG_FATAL("Could not parse %s directive at line %d%s%s",
+        processed_command, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+}
+
+/* ================================================== */
+
+static void
+other_parse_error(const char *message)
+{
+    LOG_FATAL("%s at line %d%s%s",
+        message, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+}
+
+/* ================================================== */
+
+static int
+get_number_of_args(char *line)
+{
+  int num = 0;
+
+  /* The line is normalized, between arguments is just one space */
+  if (*line == ' ')
+    line++;
+  if (*line)
+    num++;
+  for (; *line; line++) {
+    if (*line == ' ')
+      num++;
+  }
+
+  return num;
+}
+
+/* ================================================== */
+
+static void
+check_number_of_args(char *line, int num)
+{
+  num -= get_number_of_args(line);
+
+  if (num) {
+    LOG_FATAL("%s arguments for %s directive at line %d%s%s",
+        num > 0 ? "Missing" : "Too many",
+        processed_command, line_number, processed_file ? " in file " : "",
+        processed_file ? processed_file : "");
+  }
+}
+
+/* ================================================== */
+
+void
+CNF_Initialise(int r, int client_only)
+{
+  restarted = r;
+
+  hwts_interfaces = ARR_CreateInstance(sizeof (CNF_HwTsInterface));
+
+  init_sources = ARR_CreateInstance(sizeof (IPAddr));
+  ntp_sources = ARR_CreateInstance(sizeof (NTP_Source));
+  ntp_source_dirs = ARR_CreateInstance(sizeof (char *));
+  ntp_source_ids = ARR_CreateInstance(sizeof (uint32_t));
+  refclock_sources = ARR_CreateInstance(sizeof (RefclockParameters));
+  broadcasts = ARR_CreateInstance(sizeof (NTP_Broadcast_Destination));
+
+  ntp_restrictions = ARR_CreateInstance(sizeof (AllowDeny));
+  cmd_restrictions = ARR_CreateInstance(sizeof (AllowDeny));
+
+  nts_server_cert_files = ARR_CreateInstance(sizeof (char *));
+  nts_server_key_files = ARR_CreateInstance(sizeof (char *));
+  nts_trusted_certs_paths = ARR_CreateInstance(sizeof (char *));
+  nts_trusted_certs_ids = ARR_CreateInstance(sizeof (uint32_t));
+
+  rtc_device = Strdup(DEFAULT_RTC_DEVICE);
+  hwclock_file = Strdup(DEFAULT_HWCLOCK_FILE);
+  user = Strdup(DEFAULT_USER);
+
+  if (client_only) {
+    cmd_port = ntp_port = 0;
+  } else {
+    bind_cmd_path = Strdup(DEFAULT_COMMAND_SOCKET);
+    pidfile = Strdup(DEFAULT_PID_FILE);
+  }
+
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &bind_address4);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET6, &bind_address6);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &bind_acq_address4);
+  SCK_GetAnyLocalIPAddress(IPADDR_INET6, &bind_acq_address6);
+  SCK_GetLoopbackIPAddress(IPADDR_INET4, &bind_cmd_address4);
+  SCK_GetLoopbackIPAddress(IPADDR_INET6, &bind_cmd_address6);
+}
+
+/* ================================================== */
+
+void
+CNF_Finalise(void)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(hwts_interfaces); i++)
+    Free(((CNF_HwTsInterface *)ARR_GetElement(hwts_interfaces, i))->name);
+  ARR_DestroyInstance(hwts_interfaces);
+
+  for (i = 0; i < ARR_GetSize(ntp_sources); i++)
+    Free(((NTP_Source *)ARR_GetElement(ntp_sources, i))->params.name);
+  for (i = 0; i < ARR_GetSize(ntp_source_dirs); i++)
+    Free(*(char **)ARR_GetElement(ntp_source_dirs, i));
+  for (i = 0; i < ARR_GetSize(refclock_sources); i++) {
+    Free(((RefclockParameters *)ARR_GetElement(refclock_sources, i))->driver_name);
+    Free(((RefclockParameters *)ARR_GetElement(refclock_sources, i))->driver_parameter);
+  }
+  for (i = 0; i < ARR_GetSize(nts_server_cert_files); i++)
+    Free(*(char **)ARR_GetElement(nts_server_cert_files, i));
+  for (i = 0; i < ARR_GetSize(nts_server_key_files); i++)
+    Free(*(char **)ARR_GetElement(nts_server_key_files, i));
+  for (i = 0; i < ARR_GetSize(nts_trusted_certs_paths); i++)
+    Free(*(char **)ARR_GetElement(nts_trusted_certs_paths, i));
+
+  ARR_DestroyInstance(init_sources);
+  ARR_DestroyInstance(ntp_sources);
+  ARR_DestroyInstance(ntp_source_dirs);
+  ARR_DestroyInstance(ntp_source_ids);
+  ARR_DestroyInstance(refclock_sources);
+  ARR_DestroyInstance(broadcasts);
+
+  ARR_DestroyInstance(ntp_restrictions);
+  ARR_DestroyInstance(cmd_restrictions);
+
+  ARR_DestroyInstance(nts_server_cert_files);
+  ARR_DestroyInstance(nts_server_key_files);
+  ARR_DestroyInstance(nts_trusted_certs_paths);
+  ARR_DestroyInstance(nts_trusted_certs_ids);
+
+  Free(drift_file);
+  Free(dumpdir);
+  Free(hwclock_file);
+  Free(keys_file);
+  Free(leapsec_tz);
+  Free(logdir);
+  Free(bind_ntp_iface);
+  Free(bind_acq_iface);
+  Free(bind_cmd_iface);
+  Free(bind_cmd_path);
+  Free(ntp_signd_socket);
+  Free(pidfile);
+  Free(rtc_device);
+  Free(rtc_file);
+  Free(user);
+  Free(mail_user_on_change);
+  Free(tempcomp_sensor_file);
+  Free(tempcomp_point_file);
+  Free(nts_dump_dir);
+  Free(nts_ntp_server);
+}
+
+/* ================================================== */
+
+void
+CNF_EnablePrint(void)
+{
+  print_config = 1;
+}
+
+/* ================================================== */
+
+/* Read the configuration file */
+void
+CNF_ReadFile(const char *filename)
+{
+  FILE *in;
+  char line[MAX_LINE_LENGTH + 1];
+  int i;
+
+  include_level++;
+  if (include_level > MAX_INCLUDE_LEVEL)
+    LOG_FATAL("Maximum include level reached");
+
+  in = UTI_OpenFile(NULL, filename, NULL, 'R', 0);
+
+  for (i = 1; fgets(line, sizeof(line), in); i++) {
+    CNF_ParseLine(filename, i, line);
+  }
+
+  fclose(in);
+
+  include_level--;
+}
+
+/* ================================================== */
+
+/* Parse one configuration line */
+void
+CNF_ParseLine(const char *filename, int number, char *line)
+{
+  char *p, *command;
+
+  /* Set global variables used in error messages */
+  processed_file = filename;
+  line_number = number;
+
+  /* Detect truncated line */
+  if (strlen(line) >= MAX_LINE_LENGTH)
+    other_parse_error("String too long");
+
+  /* Remove extra white-space and comments */
+  CPS_NormalizeLine(line);
+
+  /* Skip blank lines */
+  if (!*line) {
+    processed_file = NULL;
+    return;
+  }
+
+  /* We have a real line, now try to match commands */
+  processed_command = command = line;
+  p = CPS_SplitWord(line);
+
+  if (print_config && strcasecmp(command, "include") && strcasecmp(command, "confdir"))
+    printf("%s%s%s\n", command, p[0] != '\0' ? " " : "", p);
+
+  if (!strcasecmp(command, "acquisitionport")) {
+    parse_int(p, &acquisition_port);
+  } else if (!strcasecmp(command, "allow")) {
+    parse_allow_deny(p, ntp_restrictions, 1);
+  } else if (!strcasecmp(command, "authselectmode")) {
+    parse_authselectmode(p);
+  } else if (!strcasecmp(command, "bindacqaddress")) {
+    parse_bindacqaddress(p);
+  } else if (!strcasecmp(command, "bindacqdevice")) {
+    parse_string(p, &bind_acq_iface);
+  } else if (!strcasecmp(command, "bindaddress")) {
+    parse_bindaddress(p);
+  } else if (!strcasecmp(command, "bindcmdaddress")) {
+    parse_bindcmdaddress(p);
+  } else if (!strcasecmp(command, "bindcmddevice")) {
+    parse_string(p, &bind_cmd_iface);
+  } else if (!strcasecmp(command, "binddevice")) {
+    parse_string(p, &bind_ntp_iface);
+  } else if (!strcasecmp(command, "broadcast")) {
+    parse_broadcast(p);
+  } else if (!strcasecmp(command, "clientloglimit")) {
+    parse_clientloglimit(p);
+  } else if (!strcasecmp(command, "clockprecision")) {
+    parse_double(p, &clock_precision);
+  } else if (!strcasecmp(command, "cmdallow")) {
+    parse_allow_deny(p, cmd_restrictions, 1);
+  } else if (!strcasecmp(command, "cmddeny")) {
+    parse_allow_deny(p, cmd_restrictions, 0);
+  } else if (!strcasecmp(command, "cmdport")) {
+    parse_int(p, &cmd_port);
+  } else if (!strcasecmp(command, "cmdratelimit")) {
+    parse_ratelimit(p, &cmd_ratelimit_enabled, &cmd_ratelimit_interval,
+                    &cmd_ratelimit_burst, &cmd_ratelimit_leak);
+  } else if (!strcasecmp(command, "combinelimit")) {
+    parse_double(p, &combine_limit);
+  } else if (!strcasecmp(command, "confdir")) {
+    parse_confdir(p);
+  } else if (!strcasecmp(command, "corrtimeratio")) {
+    parse_double(p, &correction_time_ratio);
+  } else if (!strcasecmp(command, "deny")) {
+    parse_allow_deny(p, ntp_restrictions, 0);
+  } else if (!strcasecmp(command, "driftfile")) {
+    parse_string(p, &drift_file);
+  } else if (!strcasecmp(command, "dscp")) {
+    parse_int(p, &ntp_dscp);
+  } else if (!strcasecmp(command, "dumpdir")) {
+    parse_string(p, &dumpdir);
+  } else if (!strcasecmp(command, "dumponexit")) {
+    /* Silently ignored */
+  } else if (!strcasecmp(command, "fallbackdrift")) {
+    parse_fallbackdrift(p);
+  } else if (!strcasecmp(command, "hwclockfile")) {
+    parse_string(p, &hwclock_file);
+  } else if (!strcasecmp(command, "hwtimestamp")) {
+    parse_hwtimestamp(p);
+  } else if (!strcasecmp(command, "hwtstimeout")) {
+    parse_double(p, &hwts_timeout);
+  } else if (!strcasecmp(command, "include")) {
+    parse_include(p);
+  } else if (!strcasecmp(command, "initstepslew")) {
+    parse_initstepslew(p);
+  } else if (!strcasecmp(command, "keyfile")) {
+    parse_string(p, &keys_file);
+  } else if (!strcasecmp(command, "leapsecmode")) {
+    parse_leapsecmode(p);
+  } else if (!strcasecmp(command, "leapsectz")) {
+    parse_string(p, &leapsec_tz);
+  } else if (!strcasecmp(command, "local")) {
+    parse_local(p);
+  } else if (!strcasecmp(command, "lock_all")) {
+    lock_memory = parse_null(p);
+  } else if (!strcasecmp(command, "log")) {
+    parse_log(p);
+  } else if (!strcasecmp(command, "logbanner")) {
+    parse_int(p, &log_banner);
+  } else if (!strcasecmp(command, "logchange")) {
+    parse_double(p, &log_change_threshold);
+  } else if (!strcasecmp(command, "logdir")) {
+    parse_string(p, &logdir);
+  } else if (!strcasecmp(command, "mailonchange")) {
+    parse_mailonchange(p);
+  } else if (!strcasecmp(command, "makestep")) {
+    parse_makestep(p);
+  } else if (!strcasecmp(command, "manual")) {
+    enable_manual = parse_null(p);
+  } else if (!strcasecmp(command, "maxchange")) {
+    parse_maxchange(p);
+  } else if (!strcasecmp(command, "maxclockerror")) {
+    parse_double(p, &max_clock_error);
+  } else if (!strcasecmp(command, "maxdistance")) {
+    parse_double(p, &max_distance);
+  } else if (!strcasecmp(command, "maxdrift")) {
+    parse_double(p, &max_drift);
+  } else if (!strcasecmp(command, "maxjitter")) {
+    parse_double(p, &max_jitter);
+  } else if (!strcasecmp(command, "maxntsconnections")) {
+    parse_int(p, &nts_server_connections);
+  } else if (!strcasecmp(command, "maxsamples")) {
+    parse_int(p, &max_samples);
+  } else if (!strcasecmp(command, "maxslewrate")) {
+    parse_double(p, &max_slew_rate);
+  } else if (!strcasecmp(command, "maxupdateskew")) {
+    parse_double(p, &max_update_skew);
+  } else if (!strcasecmp(command, "minsamples")) {
+    parse_int(p, &min_samples);
+  } else if (!strcasecmp(command, "minsources")) {
+    parse_int(p, &min_sources);
+  } else if (!strcasecmp(command, "nocerttimecheck")) {
+    parse_int(p, &no_cert_time_check);
+  } else if (!strcasecmp(command, "noclientlog")) {
+    no_client_log = parse_null(p);
+  } else if (!strcasecmp(command, "nosystemcert")) {
+    no_system_cert = parse_null(p);
+  } else if (!strcasecmp(command, "ntpsigndsocket")) {
+    parse_string(p, &ntp_signd_socket);
+  } else if (!strcasecmp(command, "ntsratelimit")) {
+    parse_ratelimit(p, &nts_ratelimit_enabled, &nts_ratelimit_interval,
+                    &nts_ratelimit_burst, &nts_ratelimit_leak);
+  } else if (!strcasecmp(command, "ntscachedir") ||
+             !strcasecmp(command, "ntsdumpdir")) {
+    parse_string(p, &nts_dump_dir);
+  } else if (!strcasecmp(command, "ntsntpserver")) {
+    parse_string(p, &nts_ntp_server);
+  } else if (!strcasecmp(command, "ntsport")) {
+    parse_int(p, &nts_server_port);
+  } else if (!strcasecmp(command, "ntsprocesses")) {
+    parse_int(p, &nts_server_processes);
+  } else if (!strcasecmp(command, "ntsrefresh")) {
+    parse_int(p, &nts_refresh);
+  } else if (!strcasecmp(command, "ntsrotate")) {
+    parse_int(p, &nts_rotate);
+  } else if (!strcasecmp(command, "ntsservercert")) {
+    parse_ntsserver(p, nts_server_cert_files);
+  } else if (!strcasecmp(command, "ntsserverkey")) {
+    parse_ntsserver(p, nts_server_key_files);
+  } else if (!strcasecmp(command, "ntstrustedcerts")) {
+    parse_ntstrustedcerts(p);
+  } else if (!strcasecmp(command, "peer")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "pidfile")) {
+    parse_string(p, &pidfile);
+  } else if (!strcasecmp(command, "pool")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "port")) {
+    parse_int(p, &ntp_port);
+  } else if (!strcasecmp(command, "ptpport")) {
+    parse_int(p, &ptp_port);
+  } else if (!strcasecmp(command, "ratelimit")) {
+    parse_ratelimit(p, &ntp_ratelimit_enabled, &ntp_ratelimit_interval,
+                    &ntp_ratelimit_burst, &ntp_ratelimit_leak);
+  } else if (!strcasecmp(command, "refclock")) {
+    parse_refclock(p);
+  } else if (!strcasecmp(command, "refresh")) {
+    parse_int(p, &refresh);
+  } else if (!strcasecmp(command, "reselectdist")) {
+    parse_double(p, &reselect_distance);
+  } else if (!strcasecmp(command, "rtcautotrim")) {
+    parse_double(p, &rtc_autotrim_threshold);
+  } else if (!strcasecmp(command, "rtcdevice")) {
+    parse_string(p, &rtc_device);
+  } else if (!strcasecmp(command, "rtcfile")) {
+    parse_string(p, &rtc_file);
+  } else if (!strcasecmp(command, "rtconutc")) {
+    rtc_on_utc = parse_null(p);
+  } else if (!strcasecmp(command, "rtcsync")) {
+    rtc_sync = parse_null(p);
+  } else if (!strcasecmp(command, "sched_priority")) {
+    parse_int(p, &sched_priority);
+  } else if (!strcasecmp(command, "server")) {
+    parse_source(p, command, 1);
+  } else if (!strcasecmp(command, "smoothtime")) {
+    parse_smoothtime(p);
+  } else if (!strcasecmp(command, "sourcedir")) {
+    parse_sourcedir(p);
+  } else if (!strcasecmp(command, "stratumweight")) {
+    parse_double(p, &stratum_weight);
+  } else if (!strcasecmp(command, "tempcomp")) {
+    parse_tempcomp(p);
+  } else if (!strcasecmp(command, "user")) {
+    parse_string(p, &user);
+  } else if (!strcasecmp(command, "commandkey") ||
+             !strcasecmp(command, "generatecommandkey") ||
+             !strcasecmp(command, "linux_freq_scale") ||
+             !strcasecmp(command, "linux_hz")) {
+    LOG(LOGS_WARN, "%s directive is no longer supported", command);
+  } else {
+    other_parse_error("Invalid directive");
+  }
+
+  processed_file = processed_command = NULL;
+}
+
+/* ================================================== */
+
+static int
+parse_string(char *line, char **result)
+{
+  check_number_of_args(line, 1);
+  Free(*result);
+  *result = Strdup(line);
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_int(char *line, int *result)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%d", result) != 1) {
+    command_parse_error();
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_double(char *line, double *result)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%lf", result) != 1) {
+    command_parse_error();
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_null(char *line)
+{
+  check_number_of_args(line, 0);
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+parse_source(char *line, char *type, int fatal)
+{
+  NTP_Source source;
+
+  if (strcasecmp(type, "peer") == 0) {
+    source.type = NTP_PEER;
+    source.pool = 0;
+  } else if (strcasecmp(type, "pool") == 0) {
+    source.type = NTP_SERVER;
+    source.pool = 1;
+  } else if (strcasecmp(type, "server") == 0) {
+    source.type = NTP_SERVER;
+    source.pool = 0;
+  } else {
+    if (fatal)
+      command_parse_error();
+    return;
+  }
+
+  /* Avoid comparing uninitialized data in compare_sources() */
+  memset(&source.params, 0, sizeof (source.params));
+
+  if (!CPS_ParseNTPSourceAdd(line, &source.params)) {
+    if (fatal)
+      command_parse_error();
+    return;
+  }
+
+  source.params.name = Strdup(source.params.name);
+  ARR_AppendElement(ntp_sources, &source);
+}
+
+/* ================================================== */
+
+static void
+parse_sourcedir(char *line)
+{
+  char *s;
+
+  s = Strdup(line);
+  ARR_AppendElement(ntp_source_dirs, &s);
+}
+
+/* ================================================== */
+
+static void
+parse_ratelimit(char *line, int *enabled, int *interval, int *burst, int *leak)
+{
+  int n, val;
+  char *opt;
+
+  *enabled = 1;
+
+  while (*line) {
+    opt = line;
+    line = CPS_SplitWord(line);
+    if (sscanf(line, "%d%n", &val, &n) != 1) {
+      command_parse_error();
+      return;
+    }
+    line += n;
+    if (!strcasecmp(opt, "interval"))
+      *interval = val;
+    else if (!strcasecmp(opt, "burst"))
+      *burst = val;
+    else if (!strcasecmp(opt, "leak"))
+      *leak = val;
+    else
+      command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_refclock(char *line)
+{
+  int n, poll, dpoll, filter_length, pps_rate, min_samples, max_samples, sel_options;
+  int local, max_lock_age, pps_forced, sel_option, stratum, tai;
+  uint32_t ref_id, lock_ref_id;
+  double offset, delay, precision, max_dispersion, pulse_width;
+  char *p, *cmd, *name, *param;
+  RefclockParameters *refclock;
+
+  poll = 4;
+  dpoll = 0;
+  filter_length = 64;
+  local = 0;
+  pps_forced = 0;
+  pps_rate = 0;
+  min_samples = SRC_DEFAULT_MINSAMPLES;
+  max_samples = SRC_DEFAULT_MAXSAMPLES;
+  sel_options = 0;
+  offset = 0.0;
+  delay = 1e-9;
+  precision = 0.0;
+  max_dispersion = 0.0;
+  pulse_width = 0.0;
+  ref_id = 0;
+  max_lock_age = 2;
+  lock_ref_id = 0;
+  stratum = 0;
+  tai = 0;
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  name = Strdup(p);
+
+  p = line;
+  line = CPS_SplitWord(line);
+  param = Strdup(p);
+
+  for (cmd = line; *cmd; line += n, cmd = line) {
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(cmd, "refid")) {
+      if ((n = CPS_ParseRefid(line, &ref_id)) == 0)
+        break;
+    } else if (!strcasecmp(cmd, "lock")) {
+      if ((n = CPS_ParseRefid(line, &lock_ref_id)) == 0)
+        break;
+    } else if (!strcasecmp(cmd, "poll")) {
+      if (sscanf(line, "%d%n", &poll, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "dpoll")) {
+      if (sscanf(line, "%d%n", &dpoll, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "filter")) {
+      if (sscanf(line, "%d%n", &filter_length, &n) != 1) {
+        break;
+      }
+    } else if (!strcasecmp(cmd, "local")) {
+      n = 0;
+      local = 1;
+    } else if (!strcasecmp(cmd, "rate")) {
+      if (sscanf(line, "%d%n", &pps_rate, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "minsamples")) {
+      if (sscanf(line, "%d%n", &min_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxlockage")) {
+      if (sscanf(line, "%d%n", &max_lock_age, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxsamples")) {
+      if (sscanf(line, "%d%n", &max_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "offset")) {
+      if (sscanf(line, "%lf%n", &offset, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "delay")) {
+      if (sscanf(line, "%lf%n", &delay, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "pps")) {
+      n = 0;
+      pps_forced = 1;
+    } else if (!strcasecmp(cmd, "precision")) {
+      if (sscanf(line, "%lf%n", &precision, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "maxdispersion")) {
+      if (sscanf(line, "%lf%n", &max_dispersion, &n) != 1)
+        break;
+    } else if (!strcasecmp(cmd, "stratum")) {
+      if (sscanf(line, "%d%n", &stratum, &n) != 1 ||
+          stratum >= NTP_MAX_STRATUM || stratum < 0)
+        break;
+    } else if (!strcasecmp(cmd, "tai")) {
+      n = 0;
+      tai = 1;
+    } else if (!strcasecmp(cmd, "width")) {
+      if (sscanf(line, "%lf%n", &pulse_width, &n) != 1)
+        break;
+    } else if ((sel_option = CPS_GetSelectOption(cmd)) != 0) {
+      n = 0;
+      sel_options |= sel_option;
+    } else {
+      other_parse_error("Invalid refclock option");
+      return;
+    }
+  }
+
+  if (*cmd) {
+    command_parse_error();
+    return;
+  }
+
+  refclock = (RefclockParameters *)ARR_GetNewElement(refclock_sources);
+  refclock->driver_name = name;
+  refclock->driver_parameter = param;
+  refclock->driver_poll = dpoll;
+  refclock->poll = poll;
+  refclock->filter_length = filter_length;
+  refclock->local = local;
+  refclock->pps_forced = pps_forced;
+  refclock->pps_rate = pps_rate;
+  refclock->min_samples = min_samples;
+  refclock->max_samples = max_samples;
+  refclock->sel_options = sel_options;
+  refclock->stratum = stratum;
+  refclock->tai = tai;
+  refclock->offset = offset;
+  refclock->delay = delay;
+  refclock->precision = precision;
+  refclock->max_dispersion = max_dispersion;
+  refclock->pulse_width = pulse_width;
+  refclock->ref_id = ref_id;
+  refclock->max_lock_age = max_lock_age;
+  refclock->lock_ref_id = lock_ref_id;
+}
+
+/* ================================================== */
+
+static void
+parse_log(char *line)
+{
+  char *log_name;
+  do {
+    log_name = line;
+    line = CPS_SplitWord(line);
+    if (*log_name) {
+      if (!strcmp(log_name, "rawmeasurements")) {
+        do_log_measurements = 1;
+        raw_measurements = 1;
+      } else if (!strcmp(log_name, "measurements")) {
+        do_log_measurements = 1;
+      } else if (!strcmp(log_name, "selection")) {
+        do_log_selection = 1;
+      } else if (!strcmp(log_name, "statistics")) {
+        do_log_statistics = 1;
+      } else if (!strcmp(log_name, "tracking")) {
+        do_log_tracking = 1;
+      } else if (!strcmp(log_name, "rtc")) {
+        do_log_rtc = 1;
+      } else if (!strcmp(log_name, "refclocks")) {
+        do_log_refclocks = 1;
+      } else if (!strcmp(log_name, "tempcomp")) {
+        do_log_tempcomp = 1;
+      } else {
+        other_parse_error("Invalid log parameter");
+        break;
+      }
+    } else {
+      break;
+    }
+  } while (1);
+}
+
+/* ================================================== */
+
+static void
+parse_local(char *line)
+{
+  if (!CPS_ParseLocal(line, &local_stratum, &local_orphan, &local_distance))
+    command_parse_error();
+  enable_local = 1;
+}
+
+/* ================================================== */
+
+static void
+parse_initstepslew(char *line)
+{
+  char *p, *hostname;
+  IPAddr ip_addr;
+
+  /* Ignore the line if chronyd was started with -R. */
+  if (restarted) {
+    return;
+  }
+
+  ARR_SetSize(init_sources, 0);
+  p = CPS_SplitWord(line);
+
+  if (sscanf(line, "%lf", &init_slew_threshold) != 1) {
+    command_parse_error();
+    return;
+  }
+
+  while (*p) {
+    hostname = p;
+    p = CPS_SplitWord(p);
+    if (*hostname) {
+      if (DNS_Name2IPAddress(hostname, &ip_addr, 1) == DNS_Success) {
+        ARR_AppendElement(init_sources, &ip_addr);
+      } else {
+        LOG(LOGS_WARN, "Could not resolve address of initstepslew server %s", hostname);
+      }
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_leapsecmode(char *line)
+{
+  if (!strcasecmp(line, "system"))
+    leapsec_mode = REF_LeapModeSystem;
+  else if (!strcasecmp(line, "slew"))
+    leapsec_mode = REF_LeapModeSlew;
+  else if (!strcasecmp(line, "step"))
+    leapsec_mode = REF_LeapModeStep;
+  else if (!strcasecmp(line, "ignore"))
+    leapsec_mode = REF_LeapModeIgnore;
+  else
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_clientloglimit(char *line)
+{
+  check_number_of_args(line, 1);
+  if (sscanf(line, "%lu", &client_log_limit) != 1) {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_fallbackdrift(char *line)
+{
+  check_number_of_args(line, 2);
+  if (sscanf(line, "%d %d", &fb_drift_min, &fb_drift_max) != 2) {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_makestep(char *line)
+{
+  check_number_of_args(line, 2);
+  if (sscanf(line, "%lf %d", &make_step_threshold, &make_step_limit) != 2) {
+    make_step_limit = 0;
+    command_parse_error();
+  }
+
+  /* Disable limited makestep if chronyd was started with -R. */
+  if (restarted && make_step_limit > 0) {
+    make_step_limit = 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_maxchange(char *line)
+{
+  check_number_of_args(line, 3);
+  if (sscanf(line, "%lf %d %d", &max_offset, &max_offset_delay, &max_offset_ignore) != 3) {
+    max_offset_delay = -1;
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_mailonchange(char *line)
+{
+  char *address;
+  check_number_of_args(line, 2);
+  address = line;
+  line = CPS_SplitWord(line);
+  Free(mail_user_on_change);
+  if (sscanf(line, "%lf", &mail_change_threshold) == 1) {
+    mail_user_on_change = Strdup(address);
+  } else {
+    mail_user_on_change = NULL;
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_ntsserver(char *line, ARR_Instance files)
+{
+  char *file = NULL;
+
+  parse_string(line, &file);
+  ARR_AppendElement(files, &file);
+}
+
+/* ================================================== */
+
+static void
+parse_ntstrustedcerts(char *line)
+{
+  uint32_t id;
+  char *path;
+
+  if (get_number_of_args(line) == 2) {
+    path = CPS_SplitWord(line);
+    if (sscanf(line, "%"SCNu32, &id) != 1)
+      command_parse_error();
+  } else {
+    check_number_of_args(line, 1);
+    path = line;
+    id = 0;
+  }
+
+  path = Strdup(path);
+
+  ARR_AppendElement(nts_trusted_certs_paths, &path);
+  ARR_AppendElement(nts_trusted_certs_ids, &id);
+}
+
+/* ================================================== */
+
+static void
+parse_allow_deny(char *line, ARR_Instance restrictions, int allow)
+{
+  int all, subnet_bits;
+  AllowDeny *node;
+  IPAddr ip;
+
+  if (!CPS_ParseAllowDeny(line, &all, &ip, &subnet_bits))
+    command_parse_error();
+
+  node = ARR_GetNewElement(restrictions);
+  node->allow = allow;
+  node->all = all;
+  node->ip = ip;
+  node->subnet_bits = subnet_bits;
+}
+  
+/* ================================================== */
+
+static void
+parse_authselectmode(char *line)
+{
+  if (!strcasecmp(line, "require"))
+    authselect_mode = SRC_AUTHSELECT_REQUIRE;
+  else if (!strcasecmp(line, "prefer"))
+    authselect_mode = SRC_AUTHSELECT_PREFER;
+  else if (!strcasecmp(line, "mix"))
+    authselect_mode = SRC_AUTHSELECT_MIX;
+  else if (!strcasecmp(line, "ignore"))
+    authselect_mode = SRC_AUTHSELECT_IGNORE;
+  else
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_bindacqaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+  if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_acq_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_acq_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_bindaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+  if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_bindcmdaddress(char *line)
+{
+  IPAddr ip;
+
+  check_number_of_args(line, 1);
+
+  /* Address starting with / is for the Unix domain socket */
+  if (line[0] == '/') {
+    parse_string(line, &bind_cmd_path);
+    /* / disables the socket */
+    if (strcmp(bind_cmd_path, "/") == 0) {
+      Free(bind_cmd_path);
+      bind_cmd_path = NULL;
+    }
+  } else if (UTI_StringToIP(line, &ip)) {
+    if (ip.family == IPADDR_INET4)
+      bind_cmd_address4 = ip;
+    else if (ip.family == IPADDR_INET6)
+      bind_cmd_address6 = ip;
+  } else {
+    command_parse_error();
+  }
+}
+
+/* ================================================== */
+
+static void
+parse_broadcast(char *line)
+{
+  /* Syntax : broadcast <interval> <broadcast-IP-addr> [<port>] */
+  NTP_Broadcast_Destination *destination;
+  int port;
+  int interval;
+  char *p;
+  IPAddr ip;
+  
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (sscanf(p, "%d", &interval) != 1) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!UTI_StringToIP(p, &ip)) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (*p) {
+    if (sscanf(p, "%d", &port) != 1 || *line) {
+      command_parse_error();
+      return;
+    }
+  } else {
+    /* default port */
+    port = NTP_PORT;
+  }
+
+  destination = (NTP_Broadcast_Destination *)ARR_GetNewElement(broadcasts);
+  destination->addr.ip_addr = ip;
+  destination->addr.port = port;
+  destination->interval = interval;
+}
+
+/* ================================================== */
+
+static void
+parse_smoothtime(char *line)
+{
+  if (get_number_of_args(line) != 3)
+    check_number_of_args(line, 2);
+
+  if (sscanf(line, "%lf %lf", &smooth_max_freq, &smooth_max_wander) != 2) {
+    smooth_max_freq = 0.0;
+    command_parse_error();
+  }
+
+  line = CPS_SplitWord(CPS_SplitWord(line));
+  smooth_leap_only = 0;
+
+  if (*line) {
+    if (!strcasecmp(line, "leaponly"))
+      smooth_leap_only = 1;
+    else
+      command_parse_error();
+  }
+}
+
+/* ================================================== */
+static void
+parse_tempcomp(char *line)
+{
+  char *p;
+  int point_form;
+
+  point_form = get_number_of_args(line) == 3;
+
+  if (!point_form)
+    check_number_of_args(line, 6);
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  if (!*p) {
+    command_parse_error();
+    return;
+  }
+
+  Free(tempcomp_point_file);
+
+  if (point_form) {
+    if (sscanf(line, "%lf", &tempcomp_interval) != 1) {
+      command_parse_error();
+      return;
+    }
+    tempcomp_point_file = Strdup(CPS_SplitWord(line));
+  } else {
+    if (sscanf(line, "%lf %lf %lf %lf %lf", &tempcomp_interval,
+               &tempcomp_T0, &tempcomp_k0, &tempcomp_k1, &tempcomp_k2) != 5) {
+      command_parse_error();
+      return;
+    }
+    tempcomp_point_file = NULL;
+  }
+
+  Free(tempcomp_sensor_file);
+  tempcomp_sensor_file = Strdup(p);
+}
+
+/* ================================================== */
+
+static void
+parse_hwtimestamp(char *line)
+{
+  CNF_HwTsInterface *iface;
+  int n, maxpoll_set = 0;
+  char *p, filter[5];
+
+  if (!*line) {
+    command_parse_error();
+    return;
+  }
+
+  p = line;
+  line = CPS_SplitWord(line);
+
+  iface = ARR_GetNewElement(hwts_interfaces);
+  iface->name = Strdup(p);
+  iface->minpoll = 0;
+  iface->min_samples = 2;
+  iface->max_samples = 16;
+  iface->nocrossts = 0;
+  iface->rxfilter = CNF_HWTS_RXFILTER_ANY;
+  iface->precision = 100.0e-9;
+  iface->tx_comp = 0.0;
+  iface->rx_comp = 0.0;
+
+  for (p = line; *p; line += n, p = line) {
+    line = CPS_SplitWord(line);
+
+    if (!strcasecmp(p, "maxsamples")) {
+      if (sscanf(line, "%d%n", &iface->max_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "minpoll")) {
+      if (sscanf(line, "%d%n", &iface->minpoll, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "maxpoll")) {
+      if (sscanf(line, "%d%n", &iface->maxpoll, &n) != 1)
+        break;
+      maxpoll_set = 1;
+    } else if (!strcasecmp(p, "minsamples")) {
+      if (sscanf(line, "%d%n", &iface->min_samples, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "precision")) {
+      if (sscanf(line, "%lf%n", &iface->precision, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "rxcomp")) {
+      if (sscanf(line, "%lf%n", &iface->rx_comp, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "txcomp")) {
+      if (sscanf(line, "%lf%n", &iface->tx_comp, &n) != 1)
+        break;
+    } else if (!strcasecmp(p, "rxfilter")) {
+      if (sscanf(line, "%4s%n", filter, &n) != 1)
+        break;
+      if (!strcasecmp(filter, "none"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_NONE;
+      else if (!strcasecmp(filter, "ntp"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_NTP;
+      else if (!strcasecmp(filter, "ptp"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_PTP;
+      else if (!strcasecmp(filter, "all"))
+        iface->rxfilter = CNF_HWTS_RXFILTER_ALL;
+      else
+        break;
+    } else if (!strcasecmp(p, "nocrossts")) {
+      n = 0;
+      iface->nocrossts = 1;
+    } else {
+      break;
+    }
+  }
+
+  if (*p)
+    command_parse_error();
+
+  if (!maxpoll_set)
+    iface->maxpoll = iface->minpoll + 1;
+}
+
+/* ================================================== */
+
+static const char *
+get_basename(const char *path)
+{
+  const char *b = strrchr(path, '/');
+  return b ? b + 1 : path;
+}
+
+/* ================================================== */
+
+static int
+compare_basenames(const void *a, const void *b)
+{
+  return strcmp(get_basename(*(const char * const *)a),
+                get_basename(*(const char * const *)b));
+}
+
+/* ================================================== */
+
+static int
+search_dirs(char *line, const char *suffix, void (*file_handler)(const char *path))
+{
+  char *dirs[MAX_CONF_DIRS], buf[MAX_LINE_LENGTH], *path;
+  size_t i, j, k, locations, n_dirs;
+  glob_t gl;
+
+  n_dirs = UTI_SplitString(line, dirs, MAX_CONF_DIRS);
+  if (n_dirs < 1 || n_dirs > MAX_CONF_DIRS)
+    return 0;
+
+  /* Get the paths of all config files in the specified directories */
+  for (i = 0; i < n_dirs; i++) {
+    if (snprintf(buf, sizeof (buf), "%s/*%s", dirs[i], suffix) >= sizeof (buf))
+      assert(0);
+    if (glob(buf, GLOB_NOSORT | (i > 0 ? GLOB_APPEND : 0), NULL, &gl) != 0)
+      ;
+  }
+
+  if (gl.gl_pathc > 0) {
+    /* Sort the paths by filenames */
+    qsort(gl.gl_pathv, gl.gl_pathc, sizeof (gl.gl_pathv[0]), compare_basenames);
+
+    for (i = 0; i < gl.gl_pathc; i += locations) {
+      /* Count directories containing files with this name */
+      for (j = i + 1, locations = 1; j < gl.gl_pathc; j++, locations++) {
+        if (compare_basenames(&gl.gl_pathv[i], &gl.gl_pathv[j]) != 0)
+          break;
+      }
+
+      /* Read the first file of this name in the order of the directive */
+      for (j = 0; j < n_dirs; j++) {
+        for (k = 0; k < locations; k++) {
+          path = gl.gl_pathv[i + k];
+          if (strncmp(path, dirs[j], strlen(dirs[j])) == 0 &&
+              strlen(dirs[j]) + 1 + strlen(get_basename(path)) == strlen(path)) {
+            file_handler(path);
+            break;
+          }
+        }
+        if (k < locations)
+          break;
+      }
+    }
+  }
+
+  globfree(&gl);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+parse_confdir(char *line)
+{
+  if (!search_dirs(line, ".conf", CNF_ReadFile))
+    command_parse_error();
+}
+
+/* ================================================== */
+
+static void
+parse_include(char *line)
+{
+  glob_t gl;
+  size_t i;
+  int r;
+
+  check_number_of_args(line, 1);
+
+  if ((r = glob(line,
+#ifdef GLOB_NOMAGIC
+                GLOB_NOMAGIC |
+#endif
+                GLOB_ERR, NULL, &gl)) != 0) {
+    if (r != GLOB_NOMATCH)
+      LOG_FATAL("Could not search for files matching %s", line);
+
+    DEBUG_LOG("glob of %s failed", line);
+    return;
+  }
+
+  for (i = 0; i < gl.gl_pathc; i++)
+    CNF_ReadFile(gl.gl_pathv[i]);
+
+  globfree(&gl);
+}
+
+/* ================================================== */
+
+static void
+load_source_file(const char *filename)
+{
+  char line[MAX_LINE_LENGTH + 1];
+  FILE *f;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'r', 0);
+  if (!f)
+    return;
+
+  while (fgets(line, sizeof (line), f)) {
+    /* Require lines to be terminated */
+    if (line[0] == '\0' || line[strlen(line) - 1] != '\n')
+      break;
+
+    CPS_NormalizeLine(line);
+    if (line[0] == '\0')
+      continue;
+
+    parse_source(CPS_SplitWord(line), line, 0);
+  }
+
+  fclose(f);
+}
+
+/* ================================================== */
+
+static int
+compare_sources(const void *a, const void *b)
+{
+  const NTP_Source *sa = a, *sb = b;
+  int d;
+
+  if (!sa->params.name)
+    return -1;
+  if (!sb->params.name)
+    return 1;
+  if ((d = strcmp(sa->params.name, sb->params.name)) != 0)
+    return d;
+  if ((d = (int)(sa->type) - (int)(sb->type)) != 0)
+    return d;
+  if ((d = sa->pool - sb->pool) != 0)
+    return d;
+  if ((d = sa->params.port - sb->params.port) != 0)
+    return d;
+  return memcmp(&sa->params.params, &sb->params.params, sizeof (sa->params.params));
+}
+
+/* ================================================== */
+
+static void
+reload_source_dirs(void)
+{
+  NTP_Source *prev_sources, *new_sources, *source;
+  unsigned int i, j, prev_size, new_size, unresolved;
+  uint32_t *prev_ids, *new_ids;
+  char buf[MAX_LINE_LENGTH];
+  NSR_Status s;
+  int d;
+
+  prev_size = ARR_GetSize(ntp_source_ids);
+  if (prev_size > 0 && ARR_GetSize(ntp_sources) != prev_size)
+    assert(0);
+
+  /* Save the current sources and their configuration IDs */
+  prev_ids = MallocArray(uint32_t, prev_size);
+  memcpy(prev_ids, ARR_GetElements(ntp_source_ids), prev_size * sizeof (prev_ids[0]));
+  prev_sources = MallocArray(NTP_Source, prev_size);
+  memcpy(prev_sources, ARR_GetElements(ntp_sources), prev_size * sizeof (prev_sources[0]));
+
+  /* Load the sources again */
+  ARR_SetSize(ntp_sources, 0);
+  for (i = 0; i < ARR_GetSize(ntp_source_dirs); i++) {
+    if (snprintf(buf, sizeof (buf), "%s",
+                 *(char **)ARR_GetElement(ntp_source_dirs, i)) >= sizeof (buf))
+      assert(0);
+    search_dirs(buf, ".sources", load_source_file);
+  }
+
+  /* Add new and remove existing sources according to the new configuration.
+     Avoid removing and adding the same source again to keep its state. */
+
+  new_size = ARR_GetSize(ntp_sources);
+  new_sources = ARR_GetElements(ntp_sources);
+  ARR_SetSize(ntp_source_ids, new_size);
+  new_ids = ARR_GetElements(ntp_source_ids);
+  unresolved = 0;
+
+  LOG_SetContext(LOGC_SourceFile);
+
+  qsort(new_sources, new_size, sizeof (new_sources[0]), compare_sources);
+
+  for (i = j = 0; i < prev_size || j < new_size; ) {
+    if (i < prev_size && j < new_size)
+      d = compare_sources(&prev_sources[i], &new_sources[j]);
+    else
+      d = i < prev_size ? -1 : 1;
+
+    if (d < 0) {
+      /* Remove the missing source */
+      if (prev_sources[i].params.name[0] != '\0')
+        NSR_RemoveSourcesById(prev_ids[i]);
+      i++;
+    } else if (d > 0) {
+      /* Add a newly configured source */
+      source = &new_sources[j];
+      s = NSR_AddSourceByName(source->params.name, source->params.port, source->pool,
+                              source->type, &source->params.params, &new_ids[j]);
+
+      if (s == NSR_UnresolvedName) {
+        unresolved++;
+      } else if (s != NSR_Success) {
+        LOG(LOGS_ERR, "Could not add source %s", source->params.name);
+
+        /* Mark the source as not present */
+        source->params.name[0] = '\0';
+      }
+      j++;
+    } else {
+      /* Keep the existing source */
+      new_ids[j] = prev_ids[i];
+      i++, j++;
+    }
+  }
+
+  LOG_UnsetContext(LOGC_SourceFile);
+
+  for (i = 0; i < prev_size; i++)
+    Free(prev_sources[i].params.name);
+  Free(prev_sources);
+  Free(prev_ids);
+
+  if (unresolved > 0)
+    NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+void
+CNF_CreateDirs(uid_t uid, gid_t gid)
+{
+  char *dir;
+
+  /* Create a directory for the Unix domain command socket */
+  if (bind_cmd_path) {
+    dir = UTI_PathToDir(bind_cmd_path);
+    UTI_CreateDirAndParents(dir, 0770, uid, gid);
+
+    /* Check the permissions and owner/group in case the directory already
+       existed.  It MUST NOT be accessible by others as permissions on Unix
+       domain sockets are ignored on some systems (e.g. Solaris). */
+    if (!UTI_CheckDirPermissions(dir, 0770, uid, gid)) {
+      LOG(LOGS_WARN, "Disabled command socket %s", bind_cmd_path);
+      Free(bind_cmd_path);
+      bind_cmd_path = NULL;
+    }
+
+    Free(dir);
+  }
+
+  if (logdir)
+    UTI_CreateDirAndParents(logdir, 0750, uid, gid);
+  if (dumpdir)
+    UTI_CreateDirAndParents(dumpdir, 0750, uid, gid);
+  if (nts_dump_dir)
+    UTI_CreateDirAndParents(nts_dump_dir, 0750, uid, gid);
+}
+
+/* ================================================== */
+
+void
+CNF_CheckReadOnlyAccess(void)
+{
+  unsigned int i;
+
+  if (keys_file)
+    UTI_CheckReadOnlyAccess(keys_file);
+  for (i = 0; i < ARR_GetSize(nts_server_key_files); i++)
+    UTI_CheckReadOnlyAccess(*(char **)ARR_GetElement(nts_server_key_files, i));
+}
+
+/* ================================================== */
+
+void
+CNF_AddInitSources(void)
+{
+  CPS_NTP_Source cps_source;
+  NTP_Remote_Address ntp_addr;
+  char dummy_hostname[2] = "H";
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(init_sources); i++) {
+    /* Get the default NTP params */
+    CPS_ParseNTPSourceAdd(dummy_hostname, &cps_source);
+
+    /* Add the address as a server specified with the iburst option */
+    ntp_addr.ip_addr = *(IPAddr *)ARR_GetElement(init_sources, i);
+    ntp_addr.port = cps_source.port;
+    cps_source.params.iburst = 1;
+
+    if (NSR_AddSource(&ntp_addr, NTP_SERVER, &cps_source.params, NULL) != NSR_Success)
+      LOG(LOGS_ERR, "Could not add source %s", UTI_IPToString(&ntp_addr.ip_addr));
+  }
+
+  ARR_SetSize(init_sources, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_AddSources(void)
+{
+  NTP_Source *source;
+  unsigned int i;
+  NSR_Status s;
+
+  for (i = 0; i < ARR_GetSize(ntp_sources); i++) {
+    source = (NTP_Source *)ARR_GetElement(ntp_sources, i);
+
+    s = NSR_AddSourceByName(source->params.name, source->params.port, source->pool,
+                            source->type, &source->params.params, NULL);
+    if (s != NSR_Success && s != NSR_UnresolvedName)
+      LOG(LOGS_ERR, "Could not add source %s", source->params.name);
+
+    Free(source->params.name);
+  }
+
+  ARR_SetSize(ntp_sources, 0);
+
+  reload_source_dirs();
+}
+
+/* ================================================== */
+
+void
+CNF_AddRefclocks(void)
+{
+  RefclockParameters *refclock;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclock_sources); i++) {
+    refclock = ARR_GetElement(refclock_sources, i);
+    RCL_AddRefclock(refclock);
+    Free(refclock->driver_name);
+    Free(refclock->driver_parameter);
+  }
+
+  ARR_SetSize(refclock_sources, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_AddBroadcasts(void)
+{
+  unsigned int i;
+  NTP_Broadcast_Destination *destination;
+
+  for (i = 0; i < ARR_GetSize(broadcasts); i++) {
+    destination = (NTP_Broadcast_Destination *)ARR_GetElement(broadcasts, i);
+    NCR_AddBroadcastDestination(&destination->addr, destination->interval);
+  }
+
+  ARR_SetSize(broadcasts, 0);
+}
+
+/* ================================================== */
+
+void
+CNF_ReloadSources(void)
+{
+  reload_source_dirs();
+}
+
+/* ================================================== */
+
+int
+CNF_GetNTPPort(void)
+{
+  return ntp_port;
+}
+
+/* ================================================== */
+
+int
+CNF_GetAcquisitionPort(void)
+{
+  return acquisition_port;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetDriftFile(void)
+{
+  return drift_file;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogBanner(void)
+{
+  return log_banner;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetLogDir(void)
+{
+  return logdir;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetDumpDir(void)
+{
+  return dumpdir;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogMeasurements(int *raw)
+{
+  *raw = raw_measurements;
+  return do_log_measurements;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogSelection(void)
+{
+  return do_log_selection;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogStatistics(void)
+{
+  return do_log_statistics;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogTracking(void)
+{
+  return do_log_tracking;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogRtc(void)
+{
+  return do_log_rtc;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogRefclocks(void)
+{
+  return do_log_refclocks;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLogTempComp(void)
+{
+  return do_log_tempcomp;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetKeysFile(void)
+{
+  return keys_file;
+}
+
+/* ================================================== */
+
+double
+CNF_GetRtcAutotrim(void)
+{
+  return rtc_autotrim_threshold;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetRtcFile(void)
+{
+  return rtc_file;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetRtcDevice(void)
+{
+  return rtc_device;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxUpdateSkew(void)
+{
+  return max_update_skew;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxDrift(void)
+{
+  return max_drift;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxClockError(void)
+{
+  return max_clock_error;
+}
+
+/* ================================================== */
+
+double
+CNF_GetCorrectionTimeRatio(void)
+{
+  return correction_time_ratio;
+}
+
+/* ================================================== */
+
+SRC_AuthSelectMode
+CNF_GetAuthSelectMode(void)
+{
+  return authselect_mode;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxSlewRate(void)
+{
+  return max_slew_rate;
+}
+
+/* ================================================== */
+
+double
+CNF_GetClockPrecision(void)
+{
+  return clock_precision;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxDistance(void)
+{
+  return max_distance;
+}
+
+/* ================================================== */
+
+double
+CNF_GetMaxJitter(void)
+{
+  return max_jitter;
+}
+
+/* ================================================== */
+
+double
+CNF_GetReselectDistance(void)
+{
+  return reselect_distance;
+}
+
+/* ================================================== */
+
+double
+CNF_GetStratumWeight(void)
+{
+  return stratum_weight;
+}
+
+/* ================================================== */
+
+double
+CNF_GetCombineLimit(void)
+{
+  return combine_limit;
+}
+
+/* ================================================== */
+
+int
+CNF_GetManualEnabled(void)
+{
+  return enable_manual;
+}
+
+/* ================================================== */
+
+int
+CNF_GetCommandPort(void) {
+  return cmd_port;
+}
+
+/* ================================================== */
+
+int
+CNF_AllowLocalReference(int *stratum, int *orphan, double *distance)
+{
+  if (enable_local) {
+    *stratum = local_stratum;
+    *orphan = local_orphan;
+    *distance = local_distance;
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+CNF_GetRtcOnUtc(void)
+{
+  return rtc_on_utc;
+}
+
+/* ================================================== */
+
+int
+CNF_GetRtcSync(void)
+{
+  return rtc_sync;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMakeStep(int *limit, double *threshold)
+{
+  *limit = make_step_limit;
+  *threshold = make_step_threshold;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMaxChange(int *delay, int *ignore, double *offset)
+{
+  *delay = max_offset_delay;
+  *ignore = max_offset_ignore;
+  *offset = max_offset;
+}
+
+/* ================================================== */
+
+double
+CNF_GetLogChange(void)
+{
+  return log_change_threshold;
+}
+
+/* ================================================== */
+
+void
+CNF_GetMailOnChange(int *enabled, double *threshold, char **user)
+{
+  if (mail_user_on_change) {
+    *enabled = 1;
+    *threshold = mail_change_threshold;
+    *user = mail_user_on_change;
+  } else {
+    *enabled = 0;
+    *threshold = 0.0;
+    *user = NULL;
+  }
+}  
+
+/* ================================================== */
+
+void
+CNF_SetupAccessRestrictions(void)
+{
+  AllowDeny *node;
+  int status;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(ntp_restrictions); i++) {
+    node = ARR_GetElement(ntp_restrictions, i);
+    status = NCR_AddAccessRestriction(&node->ip, node->subnet_bits, node->allow, node->all);
+    if (!status) {
+      LOG_FATAL("Bad subnet in %s/%d", UTI_IPToString(&node->ip), node->subnet_bits);
+    }
+  }
+
+  for (i = 0; i < ARR_GetSize(cmd_restrictions); i++) {
+    node = ARR_GetElement(cmd_restrictions, i);
+    status = CAM_AddAccessRestriction(&node->ip, node->subnet_bits, node->allow, node->all);
+    if (!status) {
+      LOG_FATAL("Bad subnet in %s/%d", UTI_IPToString(&node->ip), node->subnet_bits);
+    }
+  }
+
+  ARR_SetSize(ntp_restrictions, 0);
+  ARR_SetSize(cmd_restrictions, 0);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoClientLog(void)
+{
+  return no_client_log;
+}
+
+/* ================================================== */
+
+unsigned long
+CNF_GetClientLogLimit(void)
+{
+  return client_log_limit;
+}
+
+/* ================================================== */
+
+void
+CNF_GetFallbackDrifts(int *min, int *max)
+{
+  *min = fb_drift_min;
+  *max = fb_drift_max;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindAcquisitionAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_acq_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_acq_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindNtpInterface(void)
+{
+  return bind_ntp_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindAcquisitionInterface(void)
+{
+  return bind_acq_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindCommandInterface(void)
+{
+  return bind_cmd_iface;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetBindCommandPath(void)
+{
+  return bind_cmd_path;
+}
+
+/* ================================================== */
+
+void
+CNF_GetBindCommandAddress(int family, IPAddr *addr)
+{
+  if (family == IPADDR_INET4)
+    *addr = bind_cmd_address4;
+  else if (family == IPADDR_INET6)
+    *addr = bind_cmd_address6;
+  else
+    addr->family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtpDscp(void)
+{
+  return ntp_dscp;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtpSigndSocket(void)
+{
+  return ntp_signd_socket;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetPidFile(void)
+{
+  return pidfile;
+}
+
+/* ================================================== */
+
+REF_LeapMode
+CNF_GetLeapSecMode(void)
+{
+  return leapsec_mode;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetLeapSecTimezone(void)
+{
+  return leapsec_tz;
+}
+
+/* ================================================== */
+
+int
+CNF_GetSchedPriority(void)
+{
+  return sched_priority;
+}
+
+/* ================================================== */
+
+int
+CNF_GetLockMemory(void)
+{
+  return lock_memory;
+}
+
+/* ================================================== */
+
+int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = ntp_ratelimit_interval;
+  *burst = ntp_ratelimit_burst;
+  *leak = ntp_ratelimit_leak;
+  return ntp_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+int CNF_GetNtsRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = nts_ratelimit_interval;
+  *burst = nts_ratelimit_burst;
+  *leak = nts_ratelimit_leak;
+  return nts_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak)
+{
+  *interval = cmd_ratelimit_interval;
+  *burst = cmd_ratelimit_burst;
+  *leak = cmd_ratelimit_leak;
+  return cmd_ratelimit_enabled;
+}
+
+/* ================================================== */
+
+void
+CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only)
+{
+  *max_freq = smooth_max_freq;
+  *max_wander = smooth_max_wander;
+  *leap_only = smooth_leap_only;
+}
+
+/* ================================================== */
+
+void
+CNF_GetTempComp(char **file, double *interval, char **point_file, double *T0, double *k0, double *k1, double *k2)
+{
+  *file = tempcomp_sensor_file;
+  *point_file = tempcomp_point_file;
+  *interval = tempcomp_interval;
+  *T0 = tempcomp_T0;
+  *k0 = tempcomp_k0;
+  *k1 = tempcomp_k1;
+  *k2 = tempcomp_k2;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetUser(void)
+{
+  return user;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMaxSamples(void)
+{
+  return max_samples;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMinSamples(void)
+{
+  return min_samples;
+}
+
+/* ================================================== */
+
+int
+CNF_GetMinSources(void)
+{
+  return min_sources;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetHwclockFile(void)
+{
+  return hwclock_file;
+}
+
+/* ================================================== */
+
+int
+CNF_GetInitSources(void)
+{
+  return ARR_GetSize(init_sources);
+}
+
+/* ================================================== */
+
+double
+CNF_GetInitStepThreshold(void)
+{
+  return init_slew_threshold;
+}
+
+/* ================================================== */
+
+int
+CNF_GetHwTsInterface(unsigned int index, CNF_HwTsInterface **iface)
+{
+  if (index >= ARR_GetSize(hwts_interfaces))
+    return 0;
+
+  *iface = (CNF_HwTsInterface *)ARR_GetElement(hwts_interfaces, index);
+  return 1;
+}
+
+/* ================================================== */
+
+double
+CNF_GetHwTsTimeout(void)
+{
+  return hwts_timeout;
+}
+
+/* ================================================== */
+
+int
+CNF_GetPtpPort(void)
+{
+  return ptp_port;
+}
+
+/* ================================================== */
+
+int
+CNF_GetRefresh(void)
+{
+  return refresh;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtsDumpDir(void)
+{
+  return nts_dump_dir;
+}
+
+/* ================================================== */
+
+char *
+CNF_GetNtsNtpServer(void)
+{
+  return nts_ntp_server;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerCertAndKeyFiles(const char ***certs, const char ***keys)
+{
+  *certs = ARR_GetElements(nts_server_cert_files);
+  *keys = ARR_GetElements(nts_server_key_files);
+
+  if (ARR_GetSize(nts_server_cert_files) != ARR_GetSize(nts_server_key_files))
+    LOG_FATAL("Uneven number of NTS certs and keys");
+
+  return ARR_GetSize(nts_server_cert_files);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerPort(void)
+{
+  return nts_server_port;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerProcesses(void)
+{
+  return nts_server_processes;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsServerConnections(void)
+{
+  return nts_server_connections;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsRefresh(void)
+{
+  return nts_refresh;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsRotate(void)
+{
+  return nts_rotate;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNtsTrustedCertsPaths(const char ***paths, uint32_t **ids)
+{
+  *paths = ARR_GetElements(nts_trusted_certs_paths);
+  *ids = ARR_GetElements(nts_trusted_certs_ids);
+
+  if (ARR_GetSize(nts_trusted_certs_paths) != ARR_GetSize(nts_trusted_certs_ids))
+    assert(0);
+
+  return ARR_GetSize(nts_trusted_certs_paths);
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoSystemCert(void)
+{
+  return no_system_cert;
+}
+
+/* ================================================== */
+
+int
+CNF_GetNoCertTimeCheck(void)
+{
+  return no_cert_time_check;
+}
diff --git a/conf.h b/conf.h
new file mode 100644
index 0000000..58ebdeb
--- /dev/null
+++ b/conf.h
@@ -0,0 +1,176 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2013-2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for configuration module
+  */
+
+#ifndef GOT_CONF_H
+#define GOT_CONF_H
+
+#include "addressing.h"
+#include "reference.h"
+#include "sources.h"
+
+extern void CNF_Initialise(int restarted, int client_only);
+extern void CNF_Finalise(void);
+
+extern void CNF_EnablePrint(void);
+
+extern char *CNF_GetRtcDevice(void);
+
+extern void CNF_ReadFile(const char *filename);
+extern void CNF_ParseLine(const char *filename, int number, char *line);
+
+extern void CNF_CreateDirs(uid_t uid, gid_t gid);
+
+extern void CNF_CheckReadOnlyAccess(void);
+
+extern void CNF_AddInitSources(void);
+extern void CNF_AddSources(void);
+extern void CNF_AddBroadcasts(void);
+extern void CNF_AddRefclocks(void);
+
+extern void CNF_ReloadSources(void);
+
+extern int CNF_GetAcquisitionPort(void);
+extern int CNF_GetNTPPort(void);
+extern char *CNF_GetDriftFile(void);
+extern char *CNF_GetLogDir(void);
+extern char *CNF_GetDumpDir(void);
+extern int CNF_GetLogBanner(void);
+extern int CNF_GetLogMeasurements(int *raw);
+extern int CNF_GetLogSelection(void);
+extern int CNF_GetLogStatistics(void);
+extern int CNF_GetLogTracking(void);
+extern int CNF_GetLogRtc(void);
+extern int CNF_GetLogRefclocks(void);
+extern int CNF_GetLogTempComp(void);
+extern char *CNF_GetKeysFile(void);
+extern char *CNF_GetRtcFile(void);
+extern int CNF_GetManualEnabled(void);
+extern int CNF_GetCommandPort(void);
+extern int CNF_GetRtcOnUtc(void);
+extern int CNF_GetRtcSync(void);
+extern void CNF_GetMakeStep(int *limit, double *threshold);
+extern void CNF_GetMaxChange(int *delay, int *ignore, double *offset);
+extern double CNF_GetLogChange(void);
+extern void CNF_GetMailOnChange(int *enabled, double *threshold, char **user);
+extern int CNF_GetNoClientLog(void);
+extern unsigned long CNF_GetClientLogLimit(void);
+extern void CNF_GetFallbackDrifts(int *min, int *max);
+extern void CNF_GetBindAddress(int family, IPAddr *addr);
+extern void CNF_GetBindAcquisitionAddress(int family, IPAddr *addr);
+extern void CNF_GetBindCommandAddress(int family, IPAddr *addr);
+extern char *CNF_GetBindNtpInterface(void);
+extern char *CNF_GetBindAcquisitionInterface(void);
+extern char *CNF_GetBindCommandInterface(void);
+extern char *CNF_GetBindCommandPath(void);
+extern int CNF_GetNtpDscp(void);
+extern char *CNF_GetNtpSigndSocket(void);
+extern char *CNF_GetPidFile(void);
+extern REF_LeapMode CNF_GetLeapSecMode(void);
+extern char *CNF_GetLeapSecTimezone(void);
+
+/* Value returned in ppm, as read from file */
+extern double CNF_GetMaxUpdateSkew(void);
+extern double CNF_GetMaxClockError(void);
+extern double CNF_GetMaxDrift(void);
+extern double CNF_GetCorrectionTimeRatio(void);
+extern double CNF_GetMaxSlewRate(void);
+extern double CNF_GetClockPrecision(void);
+
+extern SRC_AuthSelectMode CNF_GetAuthSelectMode(void);
+extern double CNF_GetMaxDistance(void);
+extern double CNF_GetMaxJitter(void);
+extern double CNF_GetReselectDistance(void);
+extern double CNF_GetStratumWeight(void);
+extern double CNF_GetCombineLimit(void);
+
+extern int CNF_AllowLocalReference(int *stratum, int *orphan, double *distance);
+
+extern void CNF_SetupAccessRestrictions(void);
+
+extern int CNF_GetSchedPriority(void);
+extern int CNF_GetLockMemory(void);
+
+extern int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak);
+extern int CNF_GetNtsRateLimit(int *interval, int *burst, int *leak);
+extern int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak);
+extern void CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only);
+extern void CNF_GetTempComp(char **file, double *interval, char **point_file, double *T0, double *k0, double *k1, double *k2);
+
+extern char *CNF_GetUser(void);
+
+extern int CNF_GetMaxSamples(void);
+extern int CNF_GetMinSamples(void);
+
+extern int CNF_GetMinSources(void);
+
+extern double CNF_GetRtcAutotrim(void);
+extern char *CNF_GetHwclockFile(void);
+
+extern int CNF_GetInitSources(void);
+extern double CNF_GetInitStepThreshold(void);
+
+typedef enum {
+  CNF_HWTS_RXFILTER_ANY,
+  CNF_HWTS_RXFILTER_NONE,
+  CNF_HWTS_RXFILTER_NTP,
+  CNF_HWTS_RXFILTER_PTP,
+  CNF_HWTS_RXFILTER_ALL,
+} CNF_HwTs_RxFilter;
+
+typedef struct {
+  char *name;
+  int minpoll;
+  int maxpoll;
+  int min_samples;
+  int max_samples;
+  int nocrossts;
+  CNF_HwTs_RxFilter rxfilter;
+  double precision;
+  double tx_comp;
+  double rx_comp;
+} CNF_HwTsInterface;
+
+extern int CNF_GetHwTsInterface(unsigned int index, CNF_HwTsInterface **iface);
+extern double CNF_GetHwTsTimeout(void);
+
+extern int CNF_GetPtpPort(void);
+
+extern int CNF_GetRefresh(void);
+
+extern char *CNF_GetNtsDumpDir(void);
+extern char *CNF_GetNtsNtpServer(void);
+extern int CNF_GetNtsServerCertAndKeyFiles(const char ***certs, const char ***keys);
+extern int CNF_GetNtsServerPort(void);
+extern int CNF_GetNtsServerProcesses(void);
+extern int CNF_GetNtsServerConnections(void);
+extern int CNF_GetNtsRefresh(void);
+extern int CNF_GetNtsRotate(void);
+extern int CNF_GetNtsTrustedCertsPaths(const char ***paths, uint32_t **ids);
+extern int CNF_GetNoSystemCert(void);
+extern int CNF_GetNoCertTimeCheck(void);
+
+#endif /* GOT_CONF_H */
diff --git a/configure b/configure
new file mode 100755
index 0000000..81bb4b8
--- /dev/null
+++ b/configure
@@ -0,0 +1,1154 @@
+#!/bin/sh
+# =======================================================================
+#
+# chronyd/chronyc - Programs for keeping computer clocks accurate.
+#
+# Copyright (C) Richard P. Curnow  1997-2003
+# Copyright (C) Bryan Christianson  2016
+# Copyright (C) Miroslav Lichvar  2009, 2012-2022
+# Copyright (C) Stefan R. Filipek  2019
+#
+# =======================================================================
+
+# This configure script determines the operating system type and version
+
+# ======================================================================
+# FUNCTIONS
+
+#{{{ test_code
+test_code () {
+  name=$1
+  headers=$2
+  cflags=$3
+  ldflags=$4
+  code=$5
+
+  printf "%s" "Checking for $name : "
+
+  (
+    echo "#include \"config.h\""
+    for h in $headers; do
+      echo "#include <$h>"
+    done
+    echo "int main(int argc, char **argv) {"
+    echo "$code"
+    echo "return 0; }"
+  ) > conftest.c
+
+  echo "conftest.c:" >> config.log
+  cat conftest.c >> config.log
+  echo $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
+    $MYLDFLAGS >> config.log
+  $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
+    $MYLDFLAGS >> config.log 2>&1
+
+  if [ $? -eq 0 ]
+  then
+    echo "Yes"
+    result=0
+  else
+    echo "No"
+    result=1
+  fi
+  rm -f conftest.c conftest
+  echo >> config.log
+  return $result
+}
+#}}}
+#{{{ test_executable
+test_executable () {
+  name=$1
+  executable=$2
+  options=$3
+
+  printf "%s" "Checking for $name : "
+
+  echo $executable $options >> config.log
+  $executable $options >> config.log 2>&1
+
+  if [ $? -eq 0 ]
+  then
+    echo "Yes"
+    result=0
+  else
+    echo "No"
+    result=1
+  fi
+  echo >> config.log
+  return $result
+}
+#}}}
+#{{{ pkg_config
+pkg_config () {
+  $PKG_CONFIG "$@" 2>> config.log
+}
+#}}}
+#{{{ usage
+usage () {
+  cat <<EOF
+\`configure' configures this package to adapt to many kinds of systems.
+
+Usage: ./configure [OPTION]...
+
+Defaults for the options are specified in brackets.
+
+Configuration:
+  -h, --help              display this help and exit
+
+Installation directories:
+  --prefix=PREFIX         install architecture-independent files in PREFIX
+                          [/usr/local]
+  --exec-prefix=EPREFIX   install architecture-dependent files in EPREFIX
+                          [PREFIX]
+
+By default, \`make install' will install all the files in
+\`/usr/local/bin', \`/usr/local/lib' etc.  You can specify
+an installation prefix other than \`/usr/local' using \`--prefix',
+for instance \`--prefix=$HOME'.
+
+For better control, use the options below.
+  --disable-readline     Disable line editing support
+  --without-editline     Don't use editline even if it is available
+  --disable-sechash      Disable support for hashes other than MD5
+  --without-nettle       Don't use nettle even if it is available
+  --without-nss          Don't use NSS even if it is available
+  --without-tomcrypt     Don't use libtomcrypt even if it is available
+  --disable-nts          Disable NTS support
+  --without-gnutls       Don't use gnutls even if it is available
+  --disable-cmdmon       Disable command and monitoring support
+  --disable-ntp          Disable NTP support
+  --disable-refclock     Disable reference clock support
+  --disable-phc          Disable PHC refclock driver
+  --disable-pps          Disable PPS refclock driver
+  --disable-ipv6         Disable IPv6 support
+  --disable-rtc          Don't include RTC even on Linux
+  --disable-privdrop     Disable support for dropping root privileges
+  --without-libcap       Don't use libcap even if it is available
+  --enable-scfilter      Enable support for system call filtering
+  --without-seccomp      Don't use seccomp even if it is available
+  --disable-asyncdns     Disable asynchronous name resolving
+  --disable-forcednsretry Don't retry on permanent DNS error
+  --without-aes-gcm-siv  Don't use AES-GCM-SIV for NTS even if it is available
+  --without-clock-gettime Don't use clock_gettime() even if it is available
+  --disable-timestamping Disable support for SW/HW timestamping
+  --enable-ntp-signd     Enable support for MS-SNTP authentication in Samba
+  --with-ntp-era=SECONDS Specify earliest assumed NTP time in seconds
+                         since 1970-01-01 [50*365 days ago]
+  --with-user=USER       Specify default chronyd user [root]
+  --with-hwclockfile=PATH Specify default path to hwclock(8) adjtime file
+  --with-pidfile=PATH    Specify default pidfile [/var/run/chrony/chronyd.pid]
+  --with-rtcdevice=PATH  Specify default path to RTC device [/dev/rtc]
+  --with-sendmail=PATH   Path to sendmail binary [/usr/lib/sendmail]
+  --enable-debug         Enable debugging support
+
+Fine tuning of the installation directories:
+  --sysconfdir=DIR       chrony.conf location [/etc]
+  --bindir=DIR           user executables [EPREFIX/bin]
+  --sbindir=DIR          system admin executables [EPREFIX/sbin]
+  --datarootdir=DIR      data root [PREFIX/share]
+  --mandir=DIR           man documentation [DATAROOTDIR/man]
+  --docdir=DIR           documentation root [DATAROOTDIR/doc/chrony]
+  --localstatedir=DIR    modifiable single-machine data [/var]
+  --chronyrundir=DIR     location for chrony sockets [LOCALSTATEDIR/run/chrony]
+  --chronyvardir=DIR     location for chrony data [LOCALSTATEDIR/lib/chrony]
+
+Overriding system detection when cross-compiling:
+  --host-system=OS       Specify system name (uname -s)
+  --host-release=REL     Specify system release (uname -r)
+  --host-machine=CPU     Specify machine (uname -m)
+
+Some influential environment variables:
+  CC          C compiler command
+  CFLAGS      C compiler flags
+  CPPFLAGS    C preprocessor flags, e.g. -I<include dir> if you have
+              headers in a nonstandard directory <include dir>
+  LDFLAGS     linker flags, e.g. -L<lib dir> if you have libraries in a
+              nonstandard directory <lib dir>
+  PKG_CONFIG  path to pkg-config utility
+  PKG_CONFIG_PATH
+              directories to add to pkg-config's search path
+  PKG_CONFIG_LIBDIR
+              path overriding pkg-config's built-in search path
+
+Use these variables to override the choices made by \`configure' or to help
+it to find libraries and programs with nonstandard names/locations.
+
+EOF
+
+}
+#}}}
+#{{{
+add_def () {
+  if [ "x$2" = "x" ]; then
+    echo "#define $1 1" >> config.h
+  else
+    echo "#define $1 $2" >> config.h
+  fi
+}
+#}}}
+#{{{ get_features
+get_features () {
+  ff=1
+  for f; do
+    if [ "$ff" = "0" ]; then
+      printf " "
+    fi
+    if grep "define FEAT_$f" config.h > /dev/null; then
+      printf "%s" "+$f"
+    else
+      printf "%s" "-$f"
+    fi
+    ff=0
+  done
+}
+#}}}
+
+# ======================================================================
+
+
+
+OPERATINGSYSTEM=`uname -s`
+VERSION=`uname -r`
+MACHINE=`uname -m`
+
+LIBS=""
+EXTRA_LIBS=""
+EXTRA_CLI_LIBS=""
+EXTRA_OBJECTS=""
+EXTRA_CLI_OBJECTS=""
+
+feat_debug=0
+feat_cmdmon=1
+feat_ntp=1
+feat_refclock=1
+feat_readline=1
+try_editline=1
+feat_sechash=1
+try_nettle=1
+try_nss=1
+try_tomcrypt=1
+feat_nts=1
+try_gnutls=1
+feat_rtc=1
+try_rtc=0
+feat_droproot=1
+try_libcap=-1
+try_clockctl=0
+feat_scfilter=0
+try_seccomp=-1
+priv_ops=""
+feat_ipv6=1
+feat_phc=1
+try_phc=0
+feat_pps=1
+try_setsched=0
+try_lockmem=0
+feat_asyncdns=1
+feat_forcednsretry=1
+try_aes_gcm_siv=1
+try_clock_gettime=1
+try_arc4random=1
+try_recvmmsg=1
+feat_timestamping=1
+try_timestamping=0
+feat_ntp_signd=0
+ntp_era_split=""
+use_pthread=0
+default_user="root"
+default_hwclockfile=""
+default_pidfile="/var/run/chrony/chronyd.pid"
+default_rtcdevice="/dev/rtc"
+mail_program="/usr/lib/sendmail"
+
+for option
+do
+    case "$option" in
+    --enable-debug )
+      feat_debug=1
+    ;;
+    --disable-readline )
+      feat_readline=0
+    ;;
+    --without-editline )
+      try_editline=0
+    ;;
+    --prefix=* | --install_prefix=* )
+      SETPREFIX=`echo $option | sed -e 's/[^=]*=//;'`
+    ;;
+    --exec-prefix=* )
+      SETEPREFIX=`echo $option | sed -e 's/[^=]*=//;'`
+    ;;
+    --sysconfdir=* )
+      SETSYSCONFDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --bindir=* )
+      SETBINDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --sbindir=* )
+      SETSBINDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --datarootdir=* )
+      SETDATAROOTDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --mandir=* )
+      SETMANDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --docdir=* )
+      SETDOCDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --localstatedir=* )
+      SETLOCALSTATEDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --chronyrundir=* | --chronysockdir=* )
+      SETCHRONYRUNDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --chronyvardir=* )
+      SETCHRONYVARDIR=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --disable-cmdmon)
+      feat_cmdmon=0
+    ;;
+    --disable-ntp)
+      feat_ntp=0
+    ;;
+    --disable-refclock)
+      feat_refclock=0
+    ;;
+    --disable-rtc)
+      feat_rtc=0
+    ;;
+    --disable-ipv6)
+      feat_ipv6=0
+    ;;
+    --disable-phc)
+      feat_phc=0
+    ;;
+    --disable-pps)
+      feat_pps=0
+    ;;
+    --disable-privdrop)
+      feat_droproot=0
+    ;;
+    --without-libcap|--disable-linuxcaps)
+      try_libcap=0
+    ;;
+    --enable-scfilter)
+      feat_scfilter=1
+    ;;
+    --disable-scfilter)
+      feat_scfilter=0
+    ;;
+    --without-seccomp)
+      try_seccomp=0
+    ;;
+    --disable-asyncdns)
+      feat_asyncdns=0
+    ;;
+    --disable-forcednsretry)
+      feat_forcednsretry=0
+    ;;
+    --without-aes-gcm-siv)
+      try_aes_gcm_siv=0
+    ;;
+    --without-clock-gettime)
+      try_clock_gettime=0
+    ;;
+    --disable-timestamping)
+      feat_timestamping=0
+    ;;
+    --enable-ntp-signd)
+      feat_ntp_signd=1
+    ;;
+    --with-ntp-era=* )
+      ntp_era_split=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-user=* )
+      default_user=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-hwclockfile=* )
+      default_hwclockfile=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-pidfile=* )
+      default_pidfile=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-rtcdevice=* )
+      default_rtcdevice=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --with-sendmail=* )
+      mail_program=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --disable-sechash )
+      feat_sechash=0
+    ;;
+    --without-nettle )
+      try_nettle=0
+    ;;
+    --without-nss )
+      try_nss=0
+    ;;
+    --without-tomcrypt )
+      try_tomcrypt=0
+    ;;
+    --disable-nts )
+      feat_nts=0
+    ;;
+    --without-gnutls )
+      try_gnutls=0
+    ;;
+    --host-system=* )
+      OPERATINGSYSTEM=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --host-release=* )
+      VERSION=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --host-machine=* )
+      MACHINE=`echo $option | sed -e 's/^.*=//;'`
+    ;;
+    --help | -h )
+      usage
+      exit 0
+    ;;
+    * )
+    echo "Unrecognized option : " $option
+    esac
+done
+
+rm -f config.h config.log
+
+SYSTEM=${OPERATINGSYSTEM}-${MACHINE}
+
+case $OPERATINGSYSTEM in
+    Linux)
+        EXTRA_OBJECTS="sys_generic.o sys_linux.o sys_timex.o sys_posix.o"
+        [ $try_libcap != "0" ] && try_libcap=1
+        try_rtc=1
+        [ $try_seccomp != "0" ] && try_seccomp=1
+        try_timestamping=1
+        try_setsched=1
+        try_lockmem=1
+        try_phc=1
+        try_arc4random=0
+        add_def LINUX
+        echo "Configuring for " $SYSTEM
+    ;;
+    FreeBSD)
+        # recvmmsg() seems to be broken on FreeBSD 11.0 and it's just
+        # a wrapper around recvmsg()
+        try_recvmmsg=0
+        EXTRA_OBJECTS="sys_generic.o sys_netbsd.o sys_timex.o sys_posix.o"
+        try_setsched=1
+        try_lockmem=1
+        add_def FREEBSD
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIME ADJUSTTIMEX SETTIME BINDSOCKET"
+        fi
+        echo "Configuring for $SYSTEM"
+    ;;
+    NetBSD)
+        EXTRA_OBJECTS="sys_generic.o sys_netbsd.o sys_timex.o sys_posix.o"
+        try_clockctl=1
+        try_setsched=1
+        try_lockmem=1
+        add_def NETBSD
+        echo "Configuring for $SYSTEM"
+    ;;
+    Darwin)
+        EXTRA_OBJECTS="sys_macosx.o"
+        LIBS="$LIBS -lresolv"
+        add_def MACOSX
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIME SETTIME BINDSOCKET"
+        fi
+        major=`echo $VERSION | cut -d. -f1`
+        # ntp_adjtime is not available in macOS 10.12 (Darwin 16.x.x) and earlier
+        if [ $major -gt "16" ]; then
+          add_def HAVE_MACOS_SYS_TIMEX
+          EXTRA_OBJECTS="$EXTRA_OBJECTS sys_generic.o sys_netbsd.o sys_timex.o"
+          if [ $feat_droproot = "1" ]; then
+            priv_ops="$priv_ops ADJUSTTIMEX"
+          fi
+        fi
+        echo "Configuring for macOS (" $SYSTEM "macOS version" $VERSION ")"
+    ;;
+    SunOS)
+        EXTRA_OBJECTS="sys_generic.o sys_solaris.o sys_timex.o sys_posix.o"
+        LIBS="$LIBS -lsocket -lnsl -lkvm -lelf -lresolv"
+        try_setsched=1
+        try_lockmem=1
+        add_def SOLARIS
+        # These are needed to have msg_control in struct msghdr
+        add_def __EXTENSIONS__
+        add_def _XOPEN_SOURCE 1
+        add_def _XOPEN_SOURCE_EXTENDED 1
+        if [ $feat_droproot = "1" ]; then
+          add_def FEAT_PRIVDROP
+          priv_ops="ADJUSTTIMEX SETTIME BINDSOCKET"
+        fi
+        echo "Configuring for illumos (" $SYSTEM "SunOS version" $VERSION ")"
+    ;;                                                                        
+    * )
+        echo "error: $SYSTEM is not supported (yet?)"
+        exit 1
+    ;;
+esac
+
+if [ $feat_debug = "1" ]; then
+  add_def FEAT_DEBUG
+fi
+add_def DEBUG $feat_debug
+
+if [ $feat_cmdmon = "1" ]; then
+  add_def FEAT_CMDMON
+  EXTRA_OBJECTS="$EXTRA_OBJECTS cmdmon.o manual.o pktlength.o"
+fi
+
+if [ $feat_ntp = "1" ]; then
+  add_def FEAT_NTP
+  EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_auth.o ntp_core.o ntp_ext.o ntp_io.o ntp_sources.o"
+  if [ $feat_ntp_signd = "1" ]; then
+    add_def FEAT_SIGND
+    EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_signd.o"
+  fi
+else
+  feat_asyncdns=0
+  feat_timestamping=0
+fi
+
+if [ "$feat_cmdmon" = "1" ] || [ $feat_ntp = "1" ]; then
+  EXTRA_OBJECTS="$EXTRA_OBJECTS addrfilt.o clientlog.o keys.o nameserv.o"
+else
+  feat_ipv6=0
+fi
+
+if [ $feat_refclock = "1" ]; then
+  add_def FEAT_REFCLOCK
+  EXTRA_OBJECTS="$EXTRA_OBJECTS refclock.o refclock_phc.o refclock_pps.o refclock_shm.o refclock_sock.o"
+fi
+
+MYCC="$CC"
+MYCFLAGS="$CFLAGS"
+MYCPPFLAGS="$CPPFLAGS"
+MYLDFLAGS="$LDFLAGS"
+
+if [ "x$MYCC" = "x" ]; then
+  for cc in gcc clang cc ""; do
+    if [ "x$cc" = "x" ]; then
+      echo "error: no C compiler found"
+      exit 1
+    fi
+    MYCC=$cc
+    if test_code "$MYCC" '' '' '' ''; then
+      break
+    fi
+  done
+else
+  if ! test_code "$MYCC" '' '' '' ''; then
+    echo "error: C compiler $MYCC cannot create executables"
+    exit 1
+  fi
+fi
+
+if [ "x$MYCFLAGS" = "x" ]; then
+  MYCFLAGS="-O2 -g"
+
+  TESTCFLAGS="-D_FORTIFY_SOURCE=2 -fPIE"
+  TESTLDFLAGS="-pie -Wl,-z,relro,-z,now"
+  if test_code 'hardening compiler options' '' "$TESTCFLAGS" "$TESTLDFLAGS" ''; then
+    MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+    MYLDFLAGS="$MYLDFLAGS $TESTLDFLAGS"
+  fi
+  TESTCFLAGS="-fstack-protector-strong --param=ssp-buffer-size=4"
+  if test_code '-fstack-protector-strong' '' "$TESTCFLAGS" '' ''; then
+    MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+  else
+    TESTCFLAGS="-fstack-protector --param=ssp-buffer-size=4"
+    if test_code '-fstack-protector' '' "$TESTCFLAGS" '' ''; then
+      MYCFLAGS="$MYCFLAGS $TESTCFLAGS"
+    fi
+  fi
+fi
+
+TESTCFLAGS="-fwrapv"
+if test_code '-fwrapv' '' "$TESTCFLAGS" '' ''; then
+  GETDATE_CFLAGS="-fwrapv"
+else
+  GETDATE_CFLAGS=""
+fi
+
+if [ "x$MYCC" = "xgcc" ] || [ "x$MYCC" = "xclang" ]; then
+  MYCFLAGS="$MYCFLAGS -Wmissing-prototypes -Wall"
+fi
+
+if [ "x$PKG_CONFIG" = "x" ]; then
+  PKG_CONFIG=pkg-config
+fi
+
+if ! test_executable "pkg-config" $PKG_CONFIG --version; then
+  try_nettle=0
+  try_nss=0
+  try_gnutls=0
+fi
+
+if test_code '64-bit time_t' 'time.h' '' '' '
+  char x[sizeof(time_t) > 4 ? 1 : -1] = {0};
+  return x[0];'
+then
+  add_def HAVE_LONG_TIME_T 1
+
+  if [ "x$ntp_era_split" != "x" ]; then
+    split_seconds=$ntp_era_split
+    split_days=0
+  else
+    if [ "x$SOURCE_DATE_EPOCH" != "x" ]; then
+      split_seconds=$SOURCE_DATE_EPOCH
+    else
+      split_seconds=`date '+%s'`
+    fi
+    if [ "x$split_seconds" = "x" ]; then
+      echo "error: could not get current time, --with-ntp-era option is needed"
+      exit 1
+    fi
+    split_days=$((50 * 365))
+  fi
+
+  add_def NTP_ERA_SPLIT "(${split_seconds}LL - $split_days * 24 * 3600)"
+
+  date_format='+%Y-%m-%dT%H:%M:%SZ'
+
+  # Print the full NTP interval if a suitable date is found
+  if [ "x`date -u -d '1970-01-01 UTC 9 days ago 5 seconds 3 seconds' \
+    $date_format 2> /dev/null`" = "x1969-12-23T00:00:08Z" ]
+  then
+    time1="`date -u -d "1970-01-01 UTC $split_days days ago $split_seconds seconds" \
+      $date_format`"
+    time2="`date -u -d "1970-01-01 UTC $split_days days ago $split_seconds seconds 4294967296 seconds" \
+      $date_format`"
+    echo "NTP time mapped to $time1/$time2"
+  fi
+fi
+
+MATHCODE='return (int) pow(2.0, log(sqrt((double)argc)));'
+if ! test_code 'math' 'math.h' '' '' "$MATHCODE"; then
+  if test_code 'math in -lm' 'math.h' '' '-lm' "$MATHCODE"; then
+    LIBS="$LIBS -lm"
+  else
+    echo "error: could not compile/link a program which uses sqrt(), log(), pow()"
+    exit 1
+  fi
+fi
+  
+if test_code 'struct in_pktinfo' 'sys/socket.h netinet/in.h' '' '' '
+  struct in_pktinfo ipi;
+  return sizeof (ipi.ipi_spec_dst.s_addr) + IP_PKTINFO;'
+then
+  add_def HAVE_IN_PKTINFO
+fi
+
+if [ $feat_ipv6 = "1" ] && \
+  test_code 'IPv6 support' 'arpa/inet.h sys/socket.h netinet/in.h' '' "$LIBS" '
+    struct sockaddr_in6 n;
+    char p[100];
+    n.sin6_addr = in6addr_any;
+    n.sin6_scope_id = 0;
+    return !inet_ntop(AF_INET6, &n.sin6_addr.s6_addr, p, sizeof(p));'
+then
+  add_def FEAT_IPV6
+  if test_code 'struct in6_pktinfo' 'sys/socket.h netinet/in.h' '' '' '
+    return sizeof (struct in6_pktinfo) + IPV6_PKTINFO;'
+  then
+    add_def HAVE_IN6_PKTINFO
+  else
+    if test_code 'struct in6_pktinfo with _GNU_SOURCE' 'sys/socket.h netinet/in.h' \
+      '-D_GNU_SOURCE' '' 'return sizeof (struct in6_pktinfo) + IPV6_PKTINFO;'
+    then
+      add_def _GNU_SOURCE
+      add_def HAVE_IN6_PKTINFO
+    fi
+  fi
+fi
+
+if ! test_code 'O_NOFOLLOW flag' 'sys/types.h sys/stat.h fcntl.h' '' "$LIBS" \
+  'return open("/dev/null", O_NOFOLLOW);'
+then
+  if test_code 'O_NOFOLLOW flag with _GNU_SOURCE' 'sys/types.h sys/stat.h fcntl.h' \
+    '-D_GNU_SOURCE' "$LIBS" \
+    'return open("/dev/null", O_NOFOLLOW);'
+  then
+    add_def _GNU_SOURCE
+  else
+    echo "error: open() does not support O_NOFOLLOW flag"
+    exit 1
+  fi
+fi
+
+if [ $try_clock_gettime = "1" ]; then
+  if test_code 'clock_gettime()' 'time.h' '' '' \
+    'clock_gettime(CLOCK_REALTIME, (void *)1);'
+  then
+    add_def HAVE_CLOCK_GETTIME
+  else
+    if test_code 'clock_gettime() in -lrt' 'time.h' '' '-lrt' \
+      'clock_gettime(CLOCK_REALTIME, (void *)1);'
+    then
+      add_def HAVE_CLOCK_GETTIME
+      EXTRA_LIBS="$EXTRA_LIBS -lrt"
+    fi
+  fi
+fi
+
+if ! test_code 'getaddrinfo()' 'sys/types.h sys/socket.h netdb.h' '' "$LIBS" \
+  'return getaddrinfo(0, 0, 0, 0);'
+then
+  echo "error: getaddrinfo() not found"
+  exit 1
+fi
+
+if [ $feat_asyncdns = "1" ] && \
+  test_code 'pthread' 'pthread.h' '-pthread' '' '
+    pthread_t thread;
+    return (int)pthread_create(&thread, NULL, (void *)1, NULL);'
+then
+  add_def FEAT_ASYNCDNS
+  add_def USE_PTHREAD_ASYNCDNS
+  EXTRA_OBJECTS="$EXTRA_OBJECTS nameserv_async.o"
+  use_pthread=1
+fi
+
+if [ $try_arc4random = "1" ] && \
+  test_code 'arc4random_buf()' 'stdlib.h' '' '' \
+    'arc4random_buf((void *)1, 1);'
+then
+  add_def HAVE_ARC4RANDOM
+else
+  if test_code 'getrandom()' 'stdlib.h sys/random.h' '' '' \
+      'return getrandom((void *)1, 1, 0);'; then
+    add_def HAVE_GETRANDOM
+  fi
+fi
+
+RECVMMSG_CODE='
+  struct mmsghdr hdr;
+  return !recvmmsg(0, &hdr, 1, MSG_DONTWAIT, 0);'
+if [ $try_recvmmsg = "1" ]; then
+  if test_code 'recvmmsg()' 'sys/socket.h' '' "$LIBS" "$RECVMMSG_CODE"; then
+    add_def HAVE_RECVMMSG
+  else
+    if test_code 'recvmmsg() with _GNU_SOURCE' 'sys/socket.h' '-D_GNU_SOURCE' \
+      "$LIBS" "$RECVMMSG_CODE"
+    then
+      add_def _GNU_SOURCE
+      add_def HAVE_RECVMMSG
+    fi
+  fi
+fi
+
+if [ $feat_timestamping = "1" ] && [ $try_timestamping = "1" ] &&
+  test_code 'SW/HW timestamping' 'sys/types.h sys/socket.h linux/net_tstamp.h
+                                  linux/errqueue.h linux/ptp_clock.h' '' '' '
+    int val = SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_RX_SOFTWARE |
+              SOF_TIMESTAMPING_RAW_HARDWARE | SOF_TIMESTAMPING_OPT_CMSG;
+    return sizeof (struct scm_timestamping) + SCM_TSTAMP_SND + PTP_SYS_OFFSET +
+           setsockopt(0, SOL_SOCKET, SO_SELECT_ERR_QUEUE + SO_TIMESTAMPING,
+                      &val, sizeof (val));'
+then
+  add_def HAVE_LINUX_TIMESTAMPING
+  EXTRA_OBJECTS="$EXTRA_OBJECTS hwclock.o ntp_io_linux.o"
+
+  if test_code 'other timestamping options' \
+    'sys/types.h sys/socket.h linux/net_tstamp.h' '' '' '
+    struct scm_ts_pktinfo pktinfo;
+    pktinfo.if_index = pktinfo.pkt_length = 0;
+    return pktinfo.if_index + pktinfo.pkt_length + HWTSTAMP_FILTER_NTP_ALL +
+           SCM_TIMESTAMPING_PKTINFO +
+           SOF_TIMESTAMPING_OPT_PKTINFO + SOF_TIMESTAMPING_OPT_TX_SWHW;'; then
+    add_def HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP 1
+    add_def HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO 1
+    add_def HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW 1
+  fi
+fi
+
+timepps_h=""
+if [ $feat_refclock = "1" ] && [ $feat_pps = "1" ]; then
+  if test_code '<sys/timepps.h>' 'inttypes.h time.h sys/timepps.h' '' '' ''; then
+    timepps_h="sys/timepps.h"
+    add_def HAVE_SYS_TIMEPPS_H
+  else
+    if test_code '<timepps.h>' 'inttypes.h time.h timepps.h' '' '' ''; then
+      timepps_h="timepps.h"
+      add_def HAVE_TIMEPPS_H
+    fi
+  fi
+fi
+
+if [ "x$timepps_h" != "x" ] && \
+  test_code 'PPSAPI' "inttypes.h string.h time.h $timepps_h" '' '' '
+    pps_handle_t h = 0;
+    pps_info_t i;
+    struct timespec ts;
+    ts.tv_sec = ts.tv_nsec = 0;
+    return time_pps_fetch(h, PPS_TSFMT_TSPEC, &i, &ts);'
+then
+  add_def FEAT_PPS
+fi
+
+if [ $feat_droproot = "1" ] && [ $try_libcap = "1" ] && \
+  test_code \
+    libcap \
+    'sys/types.h pwd.h sys/prctl.h sys/capability.h grp.h' \
+    '' '-lcap' \
+    'prctl(PR_SET_KEEPCAPS, 1);cap_set_proc(cap_from_text("cap_sys_time=ep"));'
+then
+    add_def FEAT_PRIVDROP
+    EXTRA_LIBS="$EXTRA_LIBS -lcap"
+fi
+
+if [ $feat_droproot = "1" ] && [ $try_clockctl = "1" ] && \
+  test_code '<sys/clockctl.h>' 'sys/clockctl.h' '' '' ''
+then
+  add_def FEAT_PRIVDROP
+  priv_ops="BINDSOCKET"
+fi
+
+if [ $feat_scfilter = "1" ] && [ $try_seccomp = "1" ] && \
+  test_code seccomp 'seccomp.h' '' '-lseccomp' \
+    'seccomp_init(SCMP_ACT_KILL);'
+then
+  add_def FEAT_SCFILTER
+  if [ $feat_ntp = "1" ]; then
+    # NAME2IPADDRESS shouldn't be enabled together with a privops operation
+    # used by the main thread as the helper process works on one request at
+    # a time and the async resolver would block the main thread
+    priv_ops="NAME2IPADDRESS RELOADDNS"
+  fi
+  EXTRA_LIBS="$EXTRA_LIBS -lseccomp"
+fi
+
+if [ "x$priv_ops" != "x" ]; then
+  EXTRA_OBJECTS="$EXTRA_OBJECTS privops.o"
+  add_def PRIVOPS_HELPER
+  for o in $priv_ops; do
+    add_def PRIVOPS_$o
+  done
+fi
+
+if [ $feat_rtc = "1" ] && [ $try_rtc = "1" ] && \
+  test_code '<linux/rtc.h>' 'sys/ioctl.h linux/rtc.h' '' '' \
+    'ioctl(1, RTC_UIE_ON&RTC_UIE_OFF&RTC_RD_TIME&RTC_SET_TIME, 0&RTC_UF);'
+then
+    EXTRA_OBJECTS="$EXTRA_OBJECTS rtc_linux.o"
+    add_def FEAT_RTC
+fi
+
+if [ $feat_refclock = "1" ] && [ $feat_phc = "1" ] && [ $try_phc = "1" ] && \
+  grep '#define HAVE_CLOCK_GETTIME' config.h > /dev/null && \
+  test_code '<linux/ptp_clock.h>' 'sys/ioctl.h linux/ptp_clock.h' '' '' \
+    'ioctl(1, PTP_CLOCK_GETCAPS + PTP_SYS_OFFSET, 0);'
+then
+  grep 'HAVE_LINUX_TIMESTAMPING' config.h > /dev/null ||
+    EXTRA_OBJECTS="$EXTRA_OBJECTS hwclock.o"
+  add_def FEAT_PHC
+fi
+
+if [ $try_setsched = "1" ] && \
+  test_code \
+    'pthread_setschedparam()' \
+    'pthread.h sched.h' '-pthread' '' '
+     struct sched_param sched;
+     sched_get_priority_max(SCHED_FIFO);
+     pthread_setschedparam(pthread_self(), SCHED_FIFO, &sched);'
+then
+  add_def HAVE_PTHREAD_SETSCHEDPARAM
+  use_pthread=1
+fi
+
+if [ $try_lockmem = "1" ] && \
+  test_code \
+    'mlockall()' \
+    'sys/mman.h' '' '' '
+     mlockall(MCL_CURRENT|MCL_FUTURE);'
+then
+  add_def HAVE_MLOCKALL
+fi
+if [ $try_lockmem = "1" ] && \
+  test_code \
+    'setrlimit(RLIMIT_MEMLOCK, ...)' \
+    'sys/resource.h' '' '' '
+     struct rlimit rlim;
+     rlim.rlim_max = rlim.rlim_cur = RLIM_INFINITY;
+     setrlimit(RLIMIT_MEMLOCK, &rlim);'
+then
+  add_def HAVE_SETRLIMIT_MEMLOCK
+fi
+
+if [ $feat_forcednsretry = "1" ]
+then
+  add_def FORCE_DNSRETRY
+fi
+
+READLINE_LINK=""
+if [ $feat_readline = "1" ]; then
+  if [ $try_editline = "1" ]; then
+    if test_code editline 'stdio.h editline/readline.h' '' '-ledit' \
+      'add_history(readline("prompt"));'
+    then
+      add_def FEAT_READLINE
+      READLINE_LINK="-ledit"
+    fi
+  fi
+
+  EXTRA_CLI_LIBS="$EXTRA_CLI_LIBS $READLINE_LINK"
+fi
+
+HASH_OBJ="hash_intmd5.o"
+HASH_LINK=""
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nettle = "1" ]; then
+  test_cflags="`pkg_config --cflags nettle`"
+  test_link="`pkg_config --libs nettle`"
+  if test_code 'nettle' 'nettle/nettle-meta.h nettle/sha2.h' \
+    "$test_cflags" "$test_link" \
+    'return nettle_hashes[0]->context_size;'
+  then
+    HASH_OBJ="hash_nettle.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+
+    if test_code 'CMAC in nettle' 'nettle/cmac.h' "$test_cflags" "$test_link" \
+      'cmac128_update((void *)1, (void *)2, (void *)3, 1, (void *)4);'
+    then
+      add_def HAVE_CMAC
+      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_nettle.o"
+      EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS cmac_nettle.o"
+    fi
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nss = "1" ]; then
+  test_cflags="`pkg_config --cflags nss`"
+  test_link="`pkg_config --libs-only-L nss` -lfreebl3 -lnssutil3"
+  if test_code 'NSS' 'nss.h hasht.h nsslowhash.h' \
+    "$test_cflags" "$test_link" \
+    'NSSLOWHASH_Begin(NSSLOWHASH_NewContext(NSSLOW_Init(), HASH_AlgSHA512));'
+  then
+    HASH_OBJ="hash_nss.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_tomcrypt = "1" ]; then
+  if test_code 'tomcrypt' 'tomcrypt.h' '-I/usr/include/tomcrypt' '-ltomcrypt' \
+    'hash_memory_multi(find_hash("md5"), (void *)1, (void *)2, (void *)3, 1, (void *)4, 1);'
+  then
+    HASH_OBJ="hash_tomcrypt.o"
+    HASH_LINK="-ltomcrypt"
+    MYCPPFLAGS="$MYCPPFLAGS -I/usr/include/tomcrypt"
+    add_def FEAT_SECHASH
+  fi
+fi
+
+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_gnutls = "1" ]; then
+  test_cflags="`pkg_config --cflags gnutls`"
+  test_link="`pkg_config --libs gnutls`"
+  if test_code 'gnutls' 'gnutls/crypto.h' \
+    "$test_cflags" "$test_link" '
+      return gnutls_hash((void *)1, (void *)2, 1);'
+  then
+    HASH_OBJ="hash_gnutls.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+
+    if test_code 'CMAC in gnutls' 'gnutls/crypto.h' "$test_cflags" "$test_link" \
+      'return gnutls_hmac_init((void *)1, GNUTLS_MAC_AES_CMAC_128, (void *)2, 0);'
+    then
+      add_def HAVE_CMAC
+      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_gnutls.o"
+      EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS cmac_gnutls.o"
+    fi
+  fi
+fi
+
+EXTRA_OBJECTS="$EXTRA_OBJECTS $HASH_OBJ"
+EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS $HASH_OBJ"
+LIBS="$LIBS $HASH_LINK"
+
+if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
+  if [ "$HASH_OBJ" = "hash_gnutls.o" ]; then
+    test_cflags=""
+    test_link=""
+  else
+    test_cflags="`pkg_config --cflags gnutls`"
+    test_link="`pkg_config --libs gnutls`"
+  fi
+  if test_code 'TLS1.3 in gnutls' 'gnutls/gnutls.h' \
+    "$test_cflags" "$test_link $LIBS" '
+      return gnutls_init((void *)1, 0) + GNUTLS_TLS1_3 +
+        gnutls_priority_init2((void *)1, "", NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND) +
+        gnutls_prf_rfc5705((void *)1, 0, "", 0, "", 16, (void *)2);'
+  then
+    if test_code 'AES-SIV-CMAC in nettle' \
+      'nettle/siv-cmac.h' "" "$LIBS" \
+      'siv_cmac_aes128_set_key((void *)1, (void *)2);'
+    then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+      add_def HAVE_SIV
+      add_def HAVE_NETTLE_SIV_CMAC
+      if [ $try_aes_gcm_siv = "1" ] && test_code 'AES-GCM-SIV in nettle' \
+        'nettle/siv-gcm.h' "" "$LIBS" \
+        'siv_gcm_aes128_encrypt_message((void *)1, 0, NULL, 0, (void *)2, 16, (void *)3,
+                                        (void *)4);'
+      then
+        add_def HAVE_NETTLE_SIV_GCM
+      fi
+    else
+      if test_code 'AES-SIV-CMAC in gnutls' 'gnutls/crypto.h' \
+        "$test_cflags" "$test_link $LIBS" '
+          return gnutls_aead_cipher_init((void *)1, GNUTLS_CIPHER_AES_128_SIV, (void *)2);'
+      then
+        EXTRA_OBJECTS="$EXTRA_OBJECTS siv_gnutls.o"
+        add_def HAVE_SIV
+        if test_code 'gnutls_aead_cipher_set_key()' 'gnutls/crypto.h' \
+          "$test_cflags" "$test_link $LIBS" '
+            return gnutls_aead_cipher_set_key((void *)1, (void *)2);'
+        then
+          add_def HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+        fi
+      else
+        if test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
+          'aes128_set_encrypt_key((void *)1, (void *)2);'
+        then
+          EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+          add_def HAVE_SIV
+        fi
+      fi
+    fi
+
+    if grep '#define HAVE_SIV' config.h > /dev/null; then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
+      LIBS="$LIBS $test_link"
+      MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+      add_def FEAT_NTS
+    fi
+  fi
+fi
+
+if [ $use_pthread = "1" ]; then
+  MYCFLAGS="$MYCFLAGS -pthread"
+fi
+
+SYSCONFDIR=/etc
+if [ "x$SETSYSCONFDIR" != "x" ]; then
+  SYSCONFDIR=$SETSYSCONFDIR
+fi
+
+PREFIX=/usr/local
+if [ "x$SETPREFIX" != "x" ]; then
+  PREFIX=$SETPREFIX
+fi
+
+EPREFIX=${PREFIX}
+if [ "x$SETEPREFIX" != "x" ]; then
+  EPREFIX=$SETEPREFIX
+fi
+
+BINDIR=${EPREFIX}/bin
+if [ "x$SETBINDIR" != "x" ]; then
+  BINDIR=$SETBINDIR
+fi
+
+SBINDIR=${EPREFIX}/sbin
+if [ "x$SETSBINDIR" != "x" ]; then
+  SBINDIR=$SETSBINDIR
+fi
+
+DATAROOTDIR=${PREFIX}/share
+if [ "x$SETDATAROOTDIR" != "x" ]; then
+  DATAROOTDIR=$SETDATAROOTDIR
+fi
+
+MANDIR=${DATAROOTDIR}/man
+if [ "x$SETMANDIR" != "x" ]; then
+  MANDIR=$SETMANDIR
+fi
+
+DOCDIR=${DATAROOTDIR}/doc/chrony
+if [ "x$SETDOCDIR" != "x" ]; then
+  DOCDIR=$SETDOCDIR
+fi
+
+LOCALSTATEDIR=/var
+if [ "x$SETLOCALSTATEDIR" != "x" ]; then
+  LOCALSTATEDIR=$SETLOCALSTATEDIR
+fi
+
+CHRONYRUNDIR=${LOCALSTATEDIR}/run/chrony
+if [ "x$SETCHRONYRUNDIR" != "x" ]; then
+  CHRONYRUNDIR=$SETCHRONYRUNDIR
+fi
+
+CHRONYVARDIR=${LOCALSTATEDIR}/lib/chrony
+if [ "x$SETCHRONYVARDIR" != "x" ]; then
+  CHRONYVARDIR=$SETCHRONYVARDIR
+fi
+
+add_def DEFAULT_CONF_FILE "\"$SYSCONFDIR/chrony.conf\""
+add_def DEFAULT_HWCLOCK_FILE "\"$default_hwclockfile\""
+add_def DEFAULT_PID_FILE "\"$default_pidfile\""
+add_def DEFAULT_RTC_DEVICE "\"$default_rtcdevice\""
+add_def DEFAULT_USER "\"$default_user\""
+add_def DEFAULT_COMMAND_SOCKET "\"$CHRONYRUNDIR/chronyd.sock\""
+add_def MAIL_PROGRAM "\"$mail_program\""
+
+common_features="`get_features SECHASH IPV6 DEBUG`"
+chronyc_features="`get_features READLINE`"
+chronyd_features="`get_features CMDMON NTP REFCLOCK RTC PRIVDROP SCFILTER SIGND ASYNCDNS NTS`"
+add_def CHRONYC_FEATURES "\"$chronyc_features $common_features\""
+add_def CHRONYD_FEATURES "\"$chronyd_features $common_features\""
+echo "Features : $chronyd_features $chronyc_features $common_features"
+
+if [ -f version.txt ]; then
+  CHRONY_VERSION="`cat version.txt`"
+else
+  CHRONY_VERSION="DEVELOPMENT"
+fi
+
+add_def CHRONY_VERSION "\"${CHRONY_VERSION}\""
+
+for f in Makefile doc/Makefile test/unit/Makefile
+do
+  echo Creating $f
+  sed -e "s%@EXTRA_OBJS@%${EXTRA_OBJECTS}%;\
+          s%@EXTRA_CLI_OBJS@%${EXTRA_CLI_OBJECTS}%;\
+          s%@CC@%${MYCC}%;\
+          s%@CFLAGS@%${MYCFLAGS}%;\
+          s%@CPPFLAGS@%${MYCPPFLAGS}%;\
+          s%@LDFLAGS@%${MYLDFLAGS}%;\
+          s%@GETDATE_CFLAGS@%${GETDATE_CFLAGS}%;\
+          s%@LIBS@%${LIBS}%;\
+          s%@EXTRA_LIBS@%${EXTRA_LIBS}%;\
+          s%@EXTRA_CLI_LIBS@%${EXTRA_CLI_LIBS}%;\
+          s%@SYSCONFDIR@%${SYSCONFDIR}%;\
+          s%@BINDIR@%${BINDIR}%;\
+          s%@SBINDIR@%${SBINDIR}%;\
+          s%@DOCDIR@%${DOCDIR}%;\
+          s%@MANDIR@%${MANDIR}%;\
+          s%@LOCALSTATEDIR@%${LOCALSTATEDIR}%;\
+          s%@CHRONYRUNDIR@%${CHRONYRUNDIR}%;\
+          s%@CHRONYVARDIR@%${CHRONYVARDIR}%;\
+          s%@DEFAULT_HWCLOCK_FILE@%${default_hwclockfile}%;\
+          s%@DEFAULT_PID_FILE@%${default_pidfile}%;\
+          s%@DEFAULT_RTC_DEVICE@%${default_rtcdevice}%;\
+          s%@DEFAULT_USER@%${default_user}%;\
+          s%@CHRONY_VERSION@%${CHRONY_VERSION}%;" \
+          < ${f}.in > $f
+done
+
+# =======================================================================
+# vim:et:sw=2:ht=2:sts=2:fdm=marker:cms=#%s
+
diff --git a/contrib/andrew_bishop_1 b/contrib/andrew_bishop_1
new file mode 100644
index 0000000..4c0b437
--- /dev/null
+++ b/contrib/andrew_bishop_1
@@ -0,0 +1,114 @@
+From amb@gedanken.demon.co.uk Tue Aug 17 22:14:00 1999
+Date: Fri, 6 Aug 1999 19:00:24 +0100
+From: Andrew M. Bishop <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: Re: Chrony and laptop configuration
+
+Hi,
+
+Attached is the apmd_proxy script from the apmd-3.0beta9 distribution.
+
+The changes that I would make are the following:
+
+Replace the update_clock function (line 122) with 
+
+update_clock () {
+
+chronyd -f /etc/chrony.conf
+
+}
+
+Around line 171 (in the suspend actions section) I would kill chronyd.
+
+begin 644 apmd_proxy.gz
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+M=.J/.AL"&#-)J8O$1EZ&RM@961++:,5YDG=G>-/7Q8\UM$)7OR)B"3DA>$*A
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+MJ2^WQNG9TX<V6X/"W92$;_@))9TY##F1,3Y8.8JB,@X9<D//_=6HI\<H;"+9
+M(*Z@1-^@Z]Z>>EHC=?!^_^1H1MSAXLNKBT=/TDW23^@N'L*06S;,KB.^G+ZA
+M9+VS]`<VU(5VN'0U`\18Z1B@!,4\0UV(&_>CDE71EP'K#3JV";?N478I^50D
+MI"5+$%`FGU0ZC/P1"#Y?J7@]PB!EH&U"ELIPI4;H"B.5`L^F:DLV'&9!H!EV
+M5&:ZG-+>^=M7?Q%:P-"7%>'RC#;2\D<[%2/8VA.F[-_:/?T)%PLWLA_J]5VW
+>Z]AB9"M2/=L.+(S7D<0S_V\81H;_`M>*^#$A)0``
+`
+end
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+
diff --git a/contrib/andrew_bishop_2 b/contrib/andrew_bishop_2
new file mode 100644
index 0000000..d3ede74
--- /dev/null
+++ b/contrib/andrew_bishop_2
@@ -0,0 +1,95 @@
+From amb@gedanken.demon.co.uk Wed Sep  1 22:26:59 1999
+Date: Thu, 19 Aug 1999 17:30:14 +0100
+From: Andrew M. Bishop <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: [amb@gedanken.demon.co.uk: Chrony and laptop configuration]
+
+Hi,
+
+What you need to do is replace 10.0.0.0 with the network of the
+freeserve nameservers in the two scripts below.
+
+Other than that you can use it as is.
+
+------- Start of forwarded message -------
+From: "Andrew M. Bishop" <amb@gedanken.demon.co.uk>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: Chrony and laptop configuration
+Date: Sat, 31 Jul 1999 11:02:04 +0100
+
+Attached are the ip-up and ip-down files that I use for chrony.
+(Actually because of the way that debian works they are separate file
+in the /etc/ppp/ip-up.d directory that are run in a SysV init style).
+
+They rely on the presence of an 'ipparam demon' or 'ipparam freeserve'
+line in the PPP options file.
+
+-------------------- /etc/ppp/ip-up --------------------
+#!/bin/sh -f
+#
+# A script to start chrony
+#
+
+PPP_IPPARAM="$6"
+
+if [ $PPP_IPPARAM = "demon" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+online 255.255.255.0/158.152.1.0
+online 255.255.255.0/194.159.253.0
+EOF
+
+fi
+
+if [ $PPP_IPPARAM = "freeserve" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+online 255.255.255.0/10.0.0.0
+EOF
+
+fi
+-------------------- /etc/ppp/ip-up --------------------
+
+-------------------- /etc/ppp/ip-down --------------------
+#!/bin/sh -f
+#
+# A script to stop chrony
+#
+
+PPP_IPPARAM="$6"
+
+if [ $PPP_IPPARAM = "demon" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+offline 255.255.255.0/158.152.1.0
+offline 255.255.255.0/194.159.253.0
+EOF
+
+fi
+
+if [ $PPP_IPPARAM = "freeserve" ]; then
+
+   /usr/local/bin/chronyc << EOF
+password xxxxxxx
+offline 255.255.255.0/10.0.0.0
+EOF
+
+fi
+-------------------- /etc/ppp/ip-down --------------------
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+------- End of forwarded message -------
+
+-- 
+Andrew.
+----------------------------------------------------------------------
+Andrew M. Bishop                             amb@gedanken.demon.co.uk
+                                      http://www.gedanken.demon.co.uk/
+
diff --git a/contrib/bryan_christianson_1/README.txt b/contrib/bryan_christianson_1/README.txt
new file mode 100644
index 0000000..05bdd0c
--- /dev/null
+++ b/contrib/bryan_christianson_1/README.txt
@@ -0,0 +1,103 @@
+Notes for installing chrony on macOS
+Author: Bryan Christianson (bryan@whatroute.net)
+------------------------------------------------
+
+These files are for those admins/users who would prefer to install chrony
+from the source distribution and are intended as guidelines rather than
+being definitive. They can be edited with a plain text editor, such as
+vi, emacs or your favourite IDE (Xcode)
+
+It is assumed you are comfortable with installing software from the
+terminal command line and know how to use sudo to acquire root access.
+
+If you are not familiar with the macOS command line then
+please consider using ChronyControl from http://whatroute.net/chronycontrol.html
+
+ChronyControl provides a gui wrapper for installing these files and sets the
+necessary permissions on each file.
+
+
+Install the chrony software
+---------------------------
+
+You will need xcode and the commandline additions to build and install chrony.
+These can be obtained from Apple's website via the App Store.
+
+cd to the chrony directory
+./configure
+make
+sudo make install
+
+chrony is now installed in default locations (/usr/local/sbin/chronyd,
+/usr/local/bin/chronyc)
+
+Create a chrony.conf file - see the chrony website for details
+
+The support files here assume the following directives are specified in the
+chrony.conf file
+
+keyfile /etc/chrony.d/chrony.keys
+driftfile /var/db/chrony/chrony.drift
+bindcmdaddress /var/db/chrony/chronyd.sock
+logdir /var/log/chrony
+dumpdir /var/db/chrony
+
+Install this file as /etc/chrony.d/chrony.conf and create
+the directories specified in the above directives if they don't exist.
+You will need root permissions to create the directories.
+
+
+Running chronyd
+---------------
+At this point chronyd *could* be run as a daemon. Apple discourage running
+daemons and their preferred method uses the launchd facility. The
+support files here provide a launchd configuration file for chronyd and also
+a shell script and launchd configuration file to rotate the chronyd logs on a daily basis.
+
+
+Support files
+-------------
+Dates and sizes may differ
+-rw-r--r--  1 yourname  staff  2084  4 Aug 22:54 README.txt
+-rwxr-xr-x  1 yourname  staff   676  4 Aug 21:18 chronylogrotate.sh
+-rw-r--r--  1 yourname  staff   543 18 Jul 20:10 org.chrony-project.chronyc.plist
+-rw-r--r--  1 yourname  staff   511 19 Jun 18:30 org.chrony-project.chronyd.plist
+
+If you have used chrony support directories other than those suggested, you
+will need to edit each file and make the appropriate changes.
+
+
+Installing the support files
+----------------------------
+
+1. chronylogrotate.sh
+This is a simple shell script that deletes old log files. Unfortunately because
+of the need to run chronyc, the standard macOS logrotation does not work with
+chrony logs.
+
+This script runs on a daily basis under control of launchd and should be
+installed in the /usr/local/bin directory
+
+sudo cp chronylogrotate.sh /usr/local/bin
+sudo chmod +x /usr/local/bin/chronylogrotate.sh
+sudo chown root:wheel /usr/local/bin/chronylogrotate.sh
+
+
+2. org.chrony-project.chronyc.plist
+This file is the launchd plist that runs logrotation each day. You may
+wish to edit this file to change the time of day at which the rotation
+will run, currently 04:05 am
+
+sudo cp org.chrony-project.chronyc.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.chrony-project.chronyc.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.chrony-project.chronyc.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.chrony-project.chronyc.plist
+
+
+3. org.chrony-project.chronyd.plist
+This file is the launchd plist that runs chronyd when the Macintosh starts.
+
+sudo cp org.chrony-project.chronyd.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.chrony-project.chronyd.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.chrony-project.chronyd.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.chrony-project.chronyd.plist
diff --git a/contrib/bryan_christianson_1/chronylogrotate.sh b/contrib/bryan_christianson_1/chronylogrotate.sh
new file mode 100755
index 0000000..f919544
--- /dev/null
+++ b/contrib/bryan_christianson_1/chronylogrotate.sh
@@ -0,0 +1,58 @@
+#!/bin/sh
+
+#  chronyd/chronyc - Programs for keeping computer clocks accurate.
+#
+#  **********************************************************************
+#  * Copyright (C) Bryan Christianson  2015
+#  *
+#  * This program is free software; you can redistribute it and/or modify
+#  * it under the terms of version 2 of the GNU General Public License as
+#  * published by the Free Software Foundation.
+#  *
+#  * This program is distributed in the hope that it will be useful, but
+#  * WITHOUT ANY WARRANTY; without even the implied warranty of
+#  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+#  * General Public License for more details.
+#  *
+#  * You should have received a copy of the GNU General Public License along
+#  * with this program; if not, write to the Free Software Foundation, Inc.,
+#  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#  *
+#  **********************************************************************
+
+LOGDIR=/var/log/chrony
+
+rotate () {
+  prefix=$1
+
+  rm -f $prefix.log.10
+
+  for (( count=9; count>= 0; count-- ))
+  do
+    next=$(( $count+1 ))
+    if [ -f $prefix.log.$count ]; then
+      mv $prefix.log.$count $prefix.log.$next
+    fi
+  done
+
+  if [ -f $prefix.log ]; then
+    mv $prefix.log $prefix.log.0
+  fi
+}
+
+if [ ! -e "$LOGDIR" ]; then
+  logger -s "missing directory: $LOGDIR"
+  exit 1
+fi
+
+cd $LOGDIR
+
+rotate measurements
+rotate statistics
+rotate tracking
+
+#
+# signal chronyd via chronyc
+/usr/local/bin/chronyc cyclelogs > /dev/null
+
+exit $?
\ No newline at end of file
diff --git a/contrib/bryan_christianson_1/org.chrony-project.chronyc.plist b/contrib/bryan_christianson_1/org.chrony-project.chronyc.plist
new file mode 100644
index 0000000..94cee17
--- /dev/null
+++ b/contrib/bryan_christianson_1/org.chrony-project.chronyc.plist
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Label</key>
+	<string>org.chrony-project.logrotate</string>
+	<key>KeepAlive</key>
+	<false/>
+	<key>ProgramArguments</key>
+	<array>
+		<string>/bin/sh</string>
+		<string>/usr/local/bin/chronylogrotate.sh</string>
+	</array>
+	<key>StartCalendarInterval</key>
+	<dict>
+		<key>Minute</key>
+		<integer>5</integer>
+		<key>Hour</key>
+		<integer>4</integer>
+	</dict>
+</dict>
+</plist>
diff --git a/contrib/bryan_christianson_1/org.chrony-project.chronyd.plist b/contrib/bryan_christianson_1/org.chrony-project.chronyd.plist
new file mode 100644
index 0000000..e23fc06
--- /dev/null
+++ b/contrib/bryan_christianson_1/org.chrony-project.chronyd.plist
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Label</key>
+	<string>org.chrony-project.chronyd</string>
+	<key>Program</key>
+	<string>/usr/local/sbin/chronyd</string>
+	<key>ProgramArguments</key>
+	<array>
+		<string>chronyd</string>
+		<string>-n</string>
+		<string>-f</string>
+		<string>/private/etc/chrony.d/chrony.conf</string>
+	</array>
+	<key>KeepAlive</key>
+	<true/>
+</dict>
+</plist>
diff --git a/contrib/erik_bryer_1 b/contrib/erik_bryer_1
new file mode 100644
index 0000000..c551dfe
--- /dev/null
+++ b/contrib/erik_bryer_1
@@ -0,0 +1,65 @@
+#!/bin/sh
+#
+# chrony        Start time synchronization. This script
+#               starts chronyd.
+#
+# Hacked by:    Erik Bryer <ebryer@spots.ab.ca> using inet as a template
+#
+# chkconfig: 2345 02 82
+# description: chronyd helps keep the system time accurate by calculating \
+#              and applying correction factors to compensate for the drift \
+#              in the clock. chronyd can also correct the hardware clock \
+#              (RTC) on some systems.
+# processname: chronyd
+# config: /etc/chrony.conf
+
+# Source function library.
+. /etc/rc.d/init.d/functions
+
+# Source networking configuration.
+. /etc/sysconfig/network
+
+# Set path to include chronyd in /usr/local/sbin
+PATH="$PATH:/usr/local/sbin"
+
+[ -f /usr/local/sbin/chronyd ] || exit 0
+
+[ -f /etc/chrony.conf ] || exit 0
+
+RETVAL=0
+
+# See how we were called.
+case "$1" in
+  start)
+        # Start daemons.
+        echo -n "Starting chronyd: "
+        daemon chronyd
+	RETVAL=$?
+ 	[ $RETVAL -eq 0 ] && touch /var/lock/subsys/chrony
+	echo
+        ;;
+  stop)
+        # Stop daemons.
+        echo -n "Shutting down chronyd: "
+# If not dead killproc automatically sleeps for 4.1 seconds then does 
+# kill -9. "chrony.txt" prefers a 5 second delay, but this should be ok.
+        killproc chronyd -15
+	RETVAL=$?
+	[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/chrony
+        echo
+        ;;
+  status)
+	status chronyd
+	exit $?
+	;;
+  restart)
+	$0 stop
+	$0 start
+	;;
+  *)
+        echo "Usage: named {start|stop|status|restart}"
+        exit 1
+esac
+
+exit $RETVAL
+
diff --git a/contrib/ken_gillett_1 b/contrib/ken_gillett_1
new file mode 100644
index 0000000..48b7999
--- /dev/null
+++ b/contrib/ken_gillett_1
@@ -0,0 +1,100 @@
+#!/bin/sh
+#
+# chronyd      This shell script takes care of starting and stopping
+#              chronyd (NTP daemon).
+#
+# chkconfig: 45 80 20
+# description: chronyd is the NTP daemon.
+
+# Source function library.
+. /etc/rc.d/init.d/functions
+
+# Source networking configuration.
+. /etc/sysconfig/network
+
+# Check that networking is up.
+[ ${NETWORKING} = "no" ] && exit 0
+
+PREDIR="/usr/local"
+CHRONYD=$PREDIR"/sbin/chronyd"
+CHRONYC=$PREDIR"/bin/chronyc"
+
+[ -x $CHRONYD -a -x $CHRONYC -a -f /etc/chrony.conf ] || exit 0
+
+dochrony() {
+	if [ -z "$(pidofproc chronyd)" ]; then
+		echo -e "\n\tchronyd not running\n\n"
+		exit 2
+	fi
+	KEY=`awk '$1 == "commandkey" {print $2; exit}' /etc/chrony.conf`
+	PASSWORD=`awk '$1 == '$KEY' {print $2; exit}' /etc/chrony/keys`
+
+	$CHRONYC <<- EOF
+		password $PASSWORD
+		$@
+		quit
+	EOF
+}
+
+# make the first parameter' lower case
+set - `echo $1 | awk '{print tolower($1)}';shift;echo "$@"`
+
+# Expand any shortcuts.
+case "$1" in
+   on|1)
+	set - "online"
+	;;
+   off|0)
+	set - "offline"
+esac
+
+# See how we were called.
+case "$1" in
+   start)
+         # Start daemons.
+         echo -n "Starting chronyd: "
+         daemon $CHRONYD
+	if [ $? -eq 0 ]; then
+		echo $(pidofproc chronyd) > /var/run/chronyd.pid
+		touch /var/lock/subsys/chronyd
+	fi
+         echo
+         ;;
+   stop)
+         # Stop daemons.
+         echo -n "Shutting down chronyd: "
+	killproc chronyd
+         echo
+         rm -f /var/lock/subsys/chronyd
+         ;;
+   status)
+	status chronyd
+	;;
+   restart|reload)
+	$0 stop
+	$0 start
+	;;
+   condrestart)
+	if [ -f /var/lock/subsys/chronyd ]; then
+		$0 stop
+		$0 start
+	fi
+	;;
+   "")
+	echo "Usage: chronyd 
+{start|stop|restart|reload|condrestart|status|[on|off]line etc}"
+	exit 1
+	;;
+ 
+accheck|cmdaccheck|clients|manual|rtcdata|sources|sourcestats|tracking|clients)
+	dochrony "$@"
+	;;
+   *)
+         echo -n "Chrony $1: "
+	dochrony "$@" > /dev/null
+	[ $? -eq 0 ] && echo_success || echo_failure
+	echo
+esac
+
+exit 0
+
diff --git a/contrib/stephan_boettcher_1 b/contrib/stephan_boettcher_1
new file mode 100644
index 0000000..e5eda11
--- /dev/null
+++ b/contrib/stephan_boettcher_1
@@ -0,0 +1,162 @@
+From stephan@nevis1.nevis.columbia.edu Mon Jun  7 20:51:57 1999
+Date: 04 Jun 1999 00:17:25 -0400
+From: Stephan I. Boettcher <stephan@nevis1.nevis.columbia.edu>
+To: richard@rrbcurnow.freeserve.co.uk
+Subject: chrony 1.1 sysV startup script for notebooks
+
+
+Dear Richard,
+
+I installed chrony on my notebook, running RedHat 5.1 Linux.
+It looks like it works.  No problems.
+
+Thank you!
+
+I like to donate my sysV startup script, appended below.
+
+Special feature:  the `online' command scans the config file to
+selectively turn some servers online, depending on the pcmcia SCHEME.
+
+booting:                 /etc/rc.d/init.d/chrony start
+/etc/ppp/ip-up:          /etc/rc.d/init.d/chrony online
+/etc/ppp/ip-down:        /etc/rc.d/init.d/chrony offline
+logrotate cron:          /etc/rc.d/init.d/chrony cyclelogs
+a user:                  /etc/rc.d/init.d/chrony status
+a sysadmin:              /etc/rc.d/init.d/chrony restart
+shutdown:                /etc/rc.d/init.d/chrony stop
+
+Best regards
+Stephan
+
+-- 
+
+------------------------------------------------------------------------
+Stephan Boettcher                                   FAX: +1-914-591-4540
+Columbia University, Nevis Labs                     Tel: +1-914-591-2863
+P.O. Box 137, 136 South Broadway      mailto:stephan@nevis1.columbia.edu
+Irvington, NY 10533, USA          http://www.nevis.columbia.edu/~stephan
+------------------------------------------------------------------------
+
+########################### cut here ###################################
+#! /bin/bash
+#
+#  /etc/rc.d/init.d/chrony
+#
+#  SYS V startup script for  
+#  chrony ntp daemon 
+#  on Linux 2.0.3x notebooks with pcmcia scheme support
+#  $Id: stephan_boettcher_1,v 1.1 2000/04/24 21:36:04 richard Exp $
+#
+#  1999-06-02 SiB <stephan@nevis1.columbia.edu>
+#
+# For PCMCIA users:
+# In /etc/chrony.conf, precede the server commands for each SCHEME 
+# with a comment line that contains the word SCHEME and the name of
+# the scheme(s) that should use the servers, up to the next line that
+# contains the word SCHEME.  The servers must be `offline' and 
+# specified by their IP address.  The hostname will not do.
+#
+# Like:
+#
+#	# SCHEME nevisppp nevislan
+#	#       stephanpc.nevis.columbia.edu
+#	server  192.12.82.222   offline
+#
+#	# SCHEME desyppp desylan
+#
+#	#       dsygw2.desy.de
+#	server  131.169.30.15   offline
+#	#       dscomsa.desy.de
+#	server  131.169.197.35  offline
+
+CONF=/etc/chrony.conf
+CHRONYD=/usr/local/sbin/chronyd
+CHRONYC=/usr/local/bin/chronyc
+KEYS=/etc/chrony.keys
+
+# See if we got all we need:
+
+[ -f $CHRONYD -a -f $CHRONYC -a -r $CONF ] || exit
+
+
+[ -r $KEYS ]							\
+&& CMDKEY=`awk '/^commandkey/{print $2}' $CONF`			\
+&& PASSWORD=`awk -v KEY=$CMDKEY '$1==KEY{print $2}' $KEYS`
+
+
+case "$1" in
+
+  start)
+	echo -n "Starting chronyd "
+        $CHRONYD -r -s -f $CONF
+        echo
+        ;;
+
+  stop)
+        echo -n "Shutting down chronyd "
+	/usr/bin/killall chronyd
+        echo
+        ;;
+
+  restart)
+	$0 stop
+	$0 start
+	;;
+
+  on*)
+
+	[ -f /var/run/pcmcia-scheme ] && SCHEME=`cat /var/run/pcmcia-scheme`
+
+	awk  -v SCHEME=${SCHEME:-default}  -v PASSWORD=$PASSWORD  \
+		'
+		BEGIN { 
+			SEL=1;
+			print "password", PASSWORD; 
+		}
+		/SCHEME/ { 
+			SEL=match($0, SCHEME); 
+		}
+		SEL && /^server[ \t]*[0-9.]+[ \t].*offline/ { 
+			print "online 255.255.255.255/"  $2; 
+		}
+		'	\
+		$CONF	\
+	| $CHRONYC
+
+	;;
+
+  off*)
+	cat <<-EOF | $CHRONYC
+		password $PASSWORD
+		offline
+		trimrtc
+		dump
+		EOF
+	;;
+
+  *log*)
+	cat <<-EOF | $CHRONYC
+		password $PASSWORD
+		cyclelogs
+		EOF
+	;;
+
+  stat*)
+	cat <<-EOF | $CHRONYC
+		sources
+		sourcestats
+		tracking
+		rtcdata
+		EOF
+	;;
+
+  *)
+        echo "Usage: chronyd {start|stop|restart|status|online|offline|cyclelogs}"
+        exit 1
+	;;
+
+esac
+
+exit 0
+
+
diff --git a/contrib/wolfgang_weisselberg1 b/contrib/wolfgang_weisselberg1
new file mode 100644
index 0000000..2c41752
--- /dev/null
+++ b/contrib/wolfgang_weisselberg1
@@ -0,0 +1,118 @@
+
+> Is it possible to limit chronyc to only those commands that
+> are readonly plus those necessary to bring a dialup connection up
+> and down? That is: online offline dump writertc and password.
+
+This is trivial on the same host and workable for non-local
+hosts: use a wrapper program or script.  An *untested*
+sample follows.  To use it, best create a special user (say
+chronyc) and a special group (say chronyg).  Make the script
+chronyc:chronyg, and 4750 (suid, rwxr-x---).  Add all users
+who may run the script to the group chronyg.
+
+Make a chrony password file e.g.
+/usr/local/etc/chrony_password.  It should be owned by chronyc
+and readable only for the owner, containing only the chrony
+password (and maybe a newline) in the first line.
+
+In this way only the script (call it run_chrony, for example)
+can read the password.  It will allow only those commands you
+explicitely allow.  You can add a password check -- especially
+if you add an internet port so you can access it over the
+internet this is advisable.  You really want to add logging
+to this untested script as well.
+
+
+BTW, if you use some sort of PPP, you probably can use
+/etc/ppp/ip-up and /etc/ppp/ip-down to transparently set chrony
+on- and offline as the ip connection goes up and comes down.
+This is _far_ more user friendly, IMHO, and a DOS by switching
+chrony offline all the time is avoided as well.
+
+
+#! /usr/bin/perl -T
+use v5.6.1;
+use warnings;
+use strict;
+
+sub laundered_command();
+sub order_chrony($$);
+sub read_password();
+sub usage($);
+
+our $CHRONY = "/usr/local/bin/chronyc";
+
+# NOTE: select the file system protection wisely for the
+# PASSWORDFILE!
+our $PASSWORDFILE = "/usr/local/etc/chrony_password";
+
+our @ALLOWED_COMMANDS = (
+    'online',                 # switch online mode on
+    'offline',                # switch online mode off
+    'dump',                   # save measurements to file
+    'writerc',                # save RTC accumulated data
+
+    'clients',                # which clients are served by us?
+    'rtcdata',                # Quality of RTC measurements
+    'sources(?: -v)?',        # Show our sources (verbose)
+    'sourcestats(?: -v)?',    # How good are our sources (verbose)?
+    'tracking',               # whom do we adjust to?
+
+    # 'burst \d+/\d+',          # allow them to send bursts?
+);
+
+usage("No command given.") unless $ARGV[0];
+
+%ENV = ();    # nuke all environment variables.  Rather
+              # drastic, but better safe than sorry!
+              # Add whatever you really need to get it
+              # working (again).
+$ENV{'PATH'} = '/usr/local/bin:/bin:/usr/bin';
+
+order_chrony(laundered_command(), read_password());
+
+exit 0; # command succeeded
+                        
+############################################################
+
+sub usage($) {
+    print STDERR "Error: ", shift, "\n";
+
+    # OK, this eats the -v...
+    print STDERR "Legal commands are:\n\t", join "\n",
+      map { $_ =~ m:(\w+):; $1 } @ALLOWED_COMMANDS;
+    exit 1;     # error
+}
+
+############################################################
+
+sub laundered_command() {
+    my $regexp = "^(" . join ( "|", @ALLOWED_COMMANDS ) . ")\$";
+    my $parameters = join " ", @ARGV;
+    $parameters =~ m:$regexp: or usage("Command $parameters not allowed.");
+
+    return $1;    # this value, then, is untainted.
+};
+
+############################################################
+
+sub read_password() {
+    open PASS, $PASSWORDFILE
+      or die "Could not read protected password file: $!";
+    my $password = <PASS>;
+    chomp $password;
+    return $password;
+};
+
+############################################################
+
+sub order_chrony($$) {
+    my ($clean_command, $password) = @_;
+    open CHRONY, "| $CHRONY &> /dev/null" or die "could not run $CHRONY: $!\n";
+    print CHRONY "password $password\n";
+    print CHRONY "$clean_command\n";
+    close CHRONY
+      or die "Error running command $clean_command\n", "\ton $CHRONY: $!\n";
+}
+
+############################################################
diff --git a/doc/Makefile.in b/doc/Makefile.in
new file mode 100644
index 0000000..1777da5
--- /dev/null
+++ b/doc/Makefile.in
@@ -0,0 +1,76 @@
+ADOC = asciidoctor
+ADOC_FLAGS =
+SED = sed
+HTML_TO_TXT = w3m -dump -T text/html
+
+MAN_FILES = chrony.conf.man chronyc.man chronyd.man
+TXT_FILES = faq.txt installation.txt
+HTML_FILES = $(MAN_FILES:%.man=%.html) $(TXT_FILES:%.txt=%.html)
+MAN_IN_FILES = $(MAN_FILES:%.man=%.man.in)
+
+SYSCONFDIR = @SYSCONFDIR@
+BINDIR = @BINDIR@
+SBINDIR = @SBINDIR@
+MANDIR = @MANDIR@
+DOCDIR = @DOCDIR@
+CHRONYRUNDIR = @CHRONYRUNDIR@
+CHRONYVARDIR = @CHRONYVARDIR@
+CHRONY_VERSION = @CHRONY_VERSION@
+DEFAULT_USER = @DEFAULT_USER@
+DEFAULT_HWCLOCK_FILE = @DEFAULT_HWCLOCK_FILE@
+DEFAULT_PID_FILE = @DEFAULT_PID_FILE@
+DEFAULT_RTC_DEVICE = @DEFAULT_RTC_DEVICE@
+
+SED_COMMANDS = "s%\@SYSCONFDIR\@%$(SYSCONFDIR)%g;\
+	       s%\@BINDIR\@%$(BINDIR)%g;\
+	       s%\@SBINDIR\@%$(SBINDIR)%g;\
+	       s%\@CHRONY_VERSION\@%$(CHRONY_VERSION)%g;\
+	       s%\@DEFAULT_HWCLOCK_FILE\@%$(DEFAULT_HWCLOCK_FILE)%g;\
+	       s%\@DEFAULT_PID_FILE\@%$(DEFAULT_PID_FILE)%g;\
+	       s%\@DEFAULT_RTC_DEVICE\@%$(DEFAULT_RTC_DEVICE)%g;\
+	       s%\@DEFAULT_USER\@%$(DEFAULT_USER)%g;\
+	       s%\@CHRONYRUNDIR\@%$(CHRONYRUNDIR)%g;\
+	       s%\@CHRONYVARDIR\@%$(CHRONYVARDIR)%g;"
+
+man: $(MAN_FILES) $(MAN_IN_FILES)
+html: $(HTML_FILES)
+txt: $(TXT_FILES)
+docs: man html
+
+%.html: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b html -o - $< | $(SED) -e $(SED_COMMANDS) > $@
+
+%.man.in: %.adoc
+	$(ADOC) $(ADOC_FLAGS) -b manpage -o $@ $<
+
+%.man: %.man.in
+	$(SED) -e $(SED_COMMANDS) < $< > $@
+
+%.txt: %.html
+	$(HTML_TO_TXT) < $< > $@
+
+install: $(MAN_FILES)
+	[ -d $(DESTDIR)$(MANDIR)/man1 ] || mkdir -p $(DESTDIR)$(MANDIR)/man1
+	[ -d $(DESTDIR)$(MANDIR)/man5 ] || mkdir -p $(DESTDIR)$(MANDIR)/man5
+	[ -d $(DESTDIR)$(MANDIR)/man8 ] || mkdir -p $(DESTDIR)$(MANDIR)/man8
+	cp chronyc.man $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	chmod 644 $(DESTDIR)$(MANDIR)/man1/chronyc.1
+	cp chronyd.man $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	chmod 644 $(DESTDIR)$(MANDIR)/man8/chronyd.8
+	cp chrony.conf.man $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+	chmod 644 $(DESTDIR)$(MANDIR)/man5/chrony.conf.5
+
+install-docs: $(HTML_FILES)
+	[ -d $(DESTDIR)$(DOCDIR) ] || mkdir -p $(DESTDIR)$(DOCDIR)
+	for f in $(HTML_FILES); do \
+	  cp $$f $(DESTDIR)$(DOCDIR); \
+	  chmod 644 $(DESTDIR)$(DOCDIR)/$$f; \
+	done
+
+clean:
+	rm -f $(MAN_FILES) $(TXT_FILES) $(HTML_FILES)
+	rm -f $(MAN_IN_FILES)
+
+distclean:
+	rm -f $(MAN_FILES) $(TXT_FILES) $(HTML_FILES)
+	rm -f Makefile
diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc
new file mode 100644
index 0000000..4af870d
--- /dev/null
+++ b/doc/chrony.conf.adoc
@@ -0,0 +1,3144 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Stephen Wadeley  2016
+// Copyright (C) Bryan Christianson  2017
+// Copyright (C) Miroslav Lichvar  2009-2023
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chrony.conf(5)
+:doctype: manpage
+:man manual: Configuration Files
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+chrony.conf - chronyd configuration file
+
+== SYNOPSIS
+*chrony.conf*
+
+== DESCRIPTION
+
+This file configures the *chronyd* daemon. The compiled-in location is
+_@SYSCONFDIR@/chrony.conf_. Other locations can be specified on the
+*chronyd* command line with the *-f* option.
+
+Each directive in the configuration file is placed on a separate line. The
+following sections describe each of the directives in turn. The directives are
+not case-sensitive. Generally, the directives can occur in any order in the file
+and if a directive is specified multiple times, only the last one will be
+effective. Exceptions are noted in the descriptions.
+
+The configuration directives can also be specified directly on the *chronyd*
+command line. In this case each argument is parsed as a new line and the
+configuration file is ignored.
+
+While the number of supported directives is large, only a few of them are
+typically needed. See the <<examples,*EXAMPLES*>> section for configuration in
+typical operating scenarios.
+
+The configuration file might contain comment lines. A comment line is any line
+that starts with zero or more spaces followed by any one of the following
+characters: *!*, *;*, *#*, *%*. Any line with this format will be ignored.
+
+== DIRECTIVES
+
+=== Time sources
+
+[[server]]*server* _hostname_ [_option_]...::
+The *server* directive specifies an NTP server which can be used as a time
+source. The client-server relationship is strictly hierarchical: a client might
+synchronise its system time to that of the server, but the server's system time
+will never be influenced by that of a client.
++
+The server can be specified by its hostname or IP address. If the hostname cannot
+be resolved on start, *chronyd* will try it again in increasing intervals, and
+also when the <<chronyc.adoc#online,*online*>> command is issued in *chronyc*.
++
+The DNS record can change over time. The used address will be replaced with a
+newly resolved address when the server becomes unreachable (i.e. no valid
+response to last 8 requests), unsynchronised, a falseticker (i.e. does not
+agree with a majority of other sources), or the root distance is too large (the
+limit can be configured by the <<maxdistance,*maxdistance*>> directive). The
+automatic replacement happens at most once per 30 minutes.
++
+This directive can be used multiple times to specify multiple servers.
++
+The directive supports the following options:
++
+*minpoll* _poll_:::
+This option specifies the minimum interval between requests sent to the server
+as a power of 2 in seconds. For example, *minpoll 5* would mean that the
+polling interval should not drop below 32 seconds. The default is 6 (64
+seconds), the minimum is -7 (1/128th of a second), and the maximum is 24 (6
+months). Note that intervals shorter than 6 (64 seconds) should generally not
+be used with public servers on the Internet, because it might be considered
+abuse. A sub-second interval will be enabled only when the server is reachable
+and the round-trip delay is shorter than 10 milliseconds, i.e. the server
+should be in a local network.
+*maxpoll* _poll_:::
+This option specifies the maximum interval between requests sent to the server
+as a power of 2 in seconds. For example, *maxpoll 9* indicates that the polling
+interval should stay at or below 9 (512 seconds). The default is 10 (1024
+seconds), the minimum is -7 (1/128th of a second), and the maximum is 24 (6
+months).
+*iburst*:::
+With this option, *chronyd* will start with a burst of 4-8 requests in order to
+make the first update of the clock sooner. It will also repeat the burst every
+time the source is switched from the offline state to online with the
+<<chronyc.adoc#online,*online*>> command in *chronyc*.
+*burst*:::
+With this option, *chronyd* will send a burst of up to 4 requests when it
+cannot get a good measurement from the
+server. The number of requests in the burst is limited by the current polling
+interval to keep the average interval at or above the minimum interval, i.e.
+the current interval needs to be at least two times longer than the minimum
+interval in order to allow a burst with two requests.
+*key* _ID_:::
+The NTP protocol supports a message authentication code (MAC) to prevent
+computers having their system time upset by rogue packets being sent to them.
+The MAC is generated as a function of a key specified in the key file,
+which is specified by the <<keyfile,*keyfile*>> directive.
++
+The *key* option specifies which key (with an ID in the range 1 through 2^32-1)
+should *chronyd* use to authenticate requests sent to the server and verify its
+responses. The server must have the same key for this number configured,
+otherwise no relationship between the computers will be possible.
++
+If the server is running *ntpd* and the output size of the hash function used
+by the key is longer than 160 bits (e.g. SHA256), the *version* option needs to
+be set to 4 for compatibility.
+*nts*:::
+This option enables authentication using the Network Time Security (NTS)
+mechanism. Unlike with the *key* option, the server and client do not need to
+share a key in a key file. NTS has a Key Establishment (NTS-KE) protocol using
+the Transport Layer Security (TLS) protocol to get the keys and cookies
+required by NTS for authentication of NTP packets.
+*certset* _ID_:::
+This option specifies which set of trusted certificates should be used to verify
+the server's certificate when the *nts* option is enabled. Sets of certificates
+can be specified with the <<ntstrustedcerts,*ntstrustedcerts*>> directive. The
+default set is 0, which by default contains certificates of the system's
+default trusted certificate authorities.
+*maxdelay* _delay_:::
+*chronyd* uses the network round-trip delay to the server to determine how
+accurate a particular measurement is likely to be. Long round-trip delays
+indicate that the request, or the response, or both were delayed. If only one
+of the messages was delayed the measurement error is likely to be substantial.
++
+For small variations in the round-trip delay, *chronyd* uses a weighting scheme
+when processing the measurements. However, beyond a certain level of delay the
+measurements are likely to be so corrupted as to be useless. (This is
+particularly so on wireless networks and other slow links, where a long delay
+probably indicates a highly asymmetric delay caused by the response waiting
+behind a lot of packets related to a download of some sort).
++
+If the user knows that round trip delays above a certain level should cause the
+measurement to be ignored, this level can be defined with the *maxdelay*
+option. For example, *maxdelay 0.3* would indicate that measurements with a
+round-trip delay greater than 0.3 seconds should be ignored. The default value
+is 3 seconds and the maximum value is 1000 seconds.
+*maxdelayratio* _ratio_:::
+This option is similar to the *maxdelay* option above. *chronyd* keeps a record
+of the minimum round-trip delay amongst the previous measurements that it has
+buffered. If a measurement has a round-trip delay that is greater than the
+specified ratio times the minimum delay, it will be rejected. By default, this
+test is disabled.
+*maxdelaydevratio* _ratio_:::
+If a measurement has a ratio of the increase in the round-trip delay from the
+minimum delay amongst the previous measurements to the standard deviation of
+the previous measurements that is greater than the specified ratio, it will be
+rejected. The default is 10.0.
+*maxdelayquant* _p_:::
+This option disables the *maxdelaydevratio* test and specifies the maximum
+acceptable delay as a quantile of the round-trip delay instead of a function of
+the minimum delay amongst the buffered measurements. If a measurement has a
+round-trip delay that is greater than a long-term estimate of the _p_-quantile,
+it will be rejected.
++
+The specified _p_ value should be between 0.05 and 0.95. For example,
+*maxdelayquant 0.2* would indicate that only measurements with the lowest 20
+percent of round-trip delays should be accepted. Note that it can take many
+measurements for the estimated quantile to reach the expected value. This
+option is intended for synchronisation in mostly static local networks with
+very short polling intervals and possibly combined with the *filter* option.
+By default, this test is disabled in favour of the *maxdelaydevratio* test.
+*mindelay* _delay_:::
+This option specifies a fixed minimum round-trip delay to be used instead of
+the minimum amongst the previous measurements. This can be useful in networks
+with static configuration to improve the stability of corrections for
+asymmetric jitter, weighting of the measurements, and the *maxdelayratio* and
+*maxdelaydevratio* tests. The value should be set accurately in order to have a
+positive effect on the synchronisation.
+*asymmetry* _ratio_:::
+This option specifies the asymmetry of the network jitter on the path to the
+source, which is used to correct the measured offset according to the delay.
+The asymmetry can be between -0.5 and +0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent from
+the source back. By default, *chronyd* estimates the asymmetry automatically.
+*offset* _offset_:::
+This option specifies a correction (in seconds) which will be applied to
+offsets measured with this source. It's particularly useful to compensate for a
+known asymmetry in network delay or timestamping errors. For example, if
+packets sent to the source were on average delayed by 100 microseconds more
+than packets sent from the source back, the correction would be -0.00005 (-50
+microseconds). The default is 0.0.
+*minsamples* _samples_:::
+Set the minimum number of samples kept for this source. This overrides the
+<<minsamples,*minsamples*>> directive.
+*maxsamples* _samples_:::
+Set the maximum number of samples kept for this source. This overrides the
+<<maxsamples,*maxsamples*>> directive.
+*filter* _polls_:::
+This option enables a median filter to reduce noise in NTP measurements. The
+filter will process samples collected in the specified number of polls
+into a single sample. It is intended to be used with very short polling
+intervals in local networks where it is acceptable to generate a lot of NTP
+traffic.
+*offline*:::
+If the server will not be reachable when *chronyd* is started, the *offline*
+option can be specified. *chronyd* will not try to poll the server until it is
+enabled to do so (by using the <<chronyc.adoc#online,*online*>> command in
+*chronyc*).
+*auto_offline*:::
+With this option, the server will be assumed to have gone offline when sending
+a request fails, e.g. due to a missing route to the network. This option avoids
+the need to run the <<chronyc.adoc#offline,*offline*>> command from *chronyc*
+when disconnecting the network link. (It will still be necessary to use the
+<<chronyc.adoc#online,*online*>> command when the link has been established, to
+enable measurements to start.)
+*prefer*:::
+Prefer this source over sources without the *prefer* option.
+*noselect*:::
+Never select this source. This is particularly useful for monitoring.
+*trust*:::
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+*require*:::
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the *trust* option this might be useful to allow a trusted
+authenticated source to be safely combined with unauthenticated sources in
+order to improve the accuracy of the clock. They can be selected and used for
+synchronisation only if they agree with the trusted and required source.
+*xleave*:::
+This option enables the interleaved mode of NTP. It enables the server to
+respond with more accurate transmit timestamps (e.g. kernel or hardware
+timestamps), which cannot be contained in the transmitted packet itself and
+need to refer to a previous packet instead. This can significantly improve the
+accuracy and stability of the measurements.
++
+The interleaved mode is compatible with servers that support only the basic
+mode. Note that even
+servers that support the interleaved mode might respond in the basic mode as
+the interleaved mode requires the servers to keep some state for each client
+and the state might be dropped when there are too many clients (e.g.
+<<clientloglimit,*clientloglimit*>> is too small), or it might be overwritten
+by other clients that have the same IP address (e.g. computers behind NAT or
+someone sending requests with a spoofed source address).
++
+The *xleave* option can be combined with the *presend* option in order to
+shorten the interval in which the server has to keep the state to be able to
+respond in the interleaved mode.
+*polltarget* _target_:::
+Target number of measurements to use for the regression algorithm which
+*chronyd* will try to maintain by adjusting the polling interval between
+*minpoll* and *maxpoll*. A higher target makes *chronyd* prefer shorter polling
+intervals. The default is 8 and a useful range is from 6 to 60.
+*port* _port_:::
+This option allows the UDP port on which the server understands NTP requests to
+be specified. For normal servers this option should not be required (the
+default is 123, the standard NTP port).
+*ntsport* _port_:::
+This option specifies the TCP port on which the server is listening for NTS-KE
+connections when the *nts* option is enabled. The default is 4460.
+*presend* _poll_:::
+If the timing measurements being made by *chronyd* are the only network data
+passing between two computers, you might find that some measurements are badly
+skewed due to either the client or the server having to do an ARP lookup on the
+other party prior to transmitting a packet. This is more of a problem with long
+sampling intervals, which might be similar in duration to the lifetime of entries
+in the ARP caches of the machines.
++
+In order to avoid this problem, the *presend* option can be used. It takes a
+single integer argument, which is the smallest polling interval for which an
+extra pair of NTP packets will be exchanged between the client and the server
+prior to the actual measurement. For example, with the following option
+included in a *server* directive:
++
+----
+presend 9
+----
++
+when the polling interval is 512 seconds or more, an extra NTP client packet
+will be sent to the server a short time (2 seconds) before making the actual
+measurement.
++
+If the *presend* option is used together with the *xleave* option, *chronyd*
+will send two extra packets instead of one.
+*minstratum* _stratum_:::
+When the synchronisation source is selected from available sources, sources
+with lower stratum are normally slightly preferred. This option can be used to
+increase stratum of the source to the specified minimum, so *chronyd* will
+avoid selecting that source. This is useful with low-stratum sources that are
+known to be unreliable or inaccurate and which should be used only when other
+sources are unreachable.
+*version* _version_:::
+This option sets the NTP version of packets sent to the server. This can be
+useful when the server runs an old NTP implementation that does not respond to
+requests using a newer version. The default version depends on other options.
+If the *extfield* or *xleave* option is used, the default version is 4. If
+those options are not used and the *key* option specifies a key using a hash
+function with output size longer than 160 bits (e.g. SHA256), the default
+version is 3 for compatibility with older *chronyd* servers. In other cases,
+the default version is 4.
+*copy*:::
+This option specifies that the server and client are closely related, their
+configuration does not allow a synchronisation loop to form between them, and
+the client is allowed to assume the reference ID and stratum of the server.
+This is useful when multiple instances of `chronyd` are running on one computer
+(e.g. for security or performance reasons), one primarily operating as a client
+to synchronise the system clock and other instances started with the *-x*
+option to operate as NTP servers for other computers with their NTP clocks
+synchronised to the first instance.
+*extfield* _type_:::
+This option enables an NTPv4 extension field specified by its type as a
+hexadecimal number. It will be included in requests sent to the server and
+processed in received responses if the server supports it. Note that some
+server implementations do not respond to requests containing an unknown
+extension field (*chronyd* as a server responded to such requests since
+version 2.0).
++
+The following extension field can be enabled by this option:
++
+_F323_::::
+This is an experimental extension field for some improvements that were
+proposed for the next version of the NTP protocol (NTPv5). The field contains
+root delay and dispersion in higher resolution and a monotonic receive
+timestamp, which enables a frequency transfer between the server and client. It
+can significantly improve stability of the synchronization. Generally, it
+should be expected to work only between servers and clients running the same
+version of *chronyd*.
+{blank}:::
+
+[[pool]]*pool* _name_ [_option_]...::
+The syntax of this directive is similar to that for the <<server,*server*>>
+directive, except that it is used to specify a pool of NTP servers rather than
+a single NTP server. The pool name is expected to resolve to multiple addresses
+which might change over time.
++
+This directive can be used multiple times to specify multiple pools.
++
+All options valid in the <<server,*server*>> directive can be used in this
+directive too. There is one option specific to the *pool* directive:
++
+*maxsources* _sources_:::
+This option sets the desired number of sources to be used from the pool.
+*chronyd* will repeatedly try to resolve the name until it gets this number of
+sources responding to requests. The default value is 4 and the maximum value is
+16.
++
+An example of the *pool* directive is
++
+----
+pool pool.ntp.org iburst maxsources 3
+----
+
+[[peer]]*peer* _hostname_ [_option_]...::
+The syntax of this directive is identical to that for the <<server,*server*>>
+directive, except that it specifies a symmetric association with an NTP peer
+instead of a client/server association with an NTP server. A single symmetric
+association allows the peers to be both servers and clients to each other. This
+is mainly useful when the NTP implementation of the peer (e.g. *ntpd*) supports
+ephemeral symmetric associations and does not need to be configured with an
+address of this host. *chronyd* does not support ephemeral associations.
++
+This directive can be used multiple times to specify multiple peers.
++
+The following options of the *server* directive do not work in the *peer*
+directive: *iburst*, *burst*, *nts*, *presend*, *copy*.
++
+When using the *xleave* option, both peers must support and have enabled the
+interleaved mode, otherwise the synchronisation will work in one direction
+only.
+When a key is specified by the *key* option to enable authentication, both
+peers must use the same key and the same key number.
++
+Note that the symmetric mode is less secure than the client/server mode. A
+denial-of-service attack is possible on unauthenticated symmetric associations,
+i.e. when the peer was specified without the *key* option. An attacker who does
+not see network traffic between two hosts, but knows that they are peering with
+each other, can periodically send them unauthenticated packets with spoofed
+source addresses in order to disrupt their NTP state and prevent them from
+synchronising to each other. When the association is authenticated, an attacker
+who does see the network traffic, but cannot prevent the packets from reaching
+the other host, can still disrupt the state by replaying old packets. The
+attacker has effectively the same power as a man-in-the-middle attacker. A
+partial protection against this attack is implemented in *chronyd*, which can
+protect the peers if they are using the same polling interval and they never
+sent an authenticated packet with a timestamp from future, but it should not be
+relied on as it is difficult to ensure the conditions are met. If two hosts
+should be able to synchronise to each other in both directions, it is
+recommended to use two separate client/server associations (specified by the
+<<server,*server*>> directive on both hosts) instead.
+
+[[initstepslew]]*initstepslew* _step-threshold_ [_hostname_]...::
+(This directive is deprecated in favour of the <<makestep,*makestep*>>
+directive.)
++
+The purpose of the *initstepslew* directive is to allow *chronyd* to make a
+rapid measurement of the system clock error at boot time, and to correct the
+system clock by stepping before normal operation begins. Since this would
+normally be performed only at an appropriate point in the system boot sequence,
+no other software should be adversely affected by the step.
++
+If the correction required is less than a specified threshold, a slew is used
+instead. This makes it safer to restart *chronyd* whilst the system is in
+normal operation.
++
+The *initstepslew* directive takes a threshold and a list of NTP servers as
+arguments. Each of the servers is rapidly polled several times, and a majority
+voting mechanism used to find the most likely range of system clock error that
+is present. A step or slew is applied to the system clock to correct this
+error. *chronyd* then enters its normal operating mode.
++
+An example of the use of the directive is:
++
+----
+initstepslew 30 foo.example.net bar.example.net baz.example.net
+----
++
+where 3 NTP servers are used to make the measurement. The _30_ indicates that
+if the system's error is found to be 30 seconds or less, a slew will be used to
+correct it; if the error is above 30 seconds, a step will be used.
++
+The *initstepslew* directive can also be used in an isolated LAN environment,
+where the clocks are set manually. The most stable computer is chosen as the
+primary server and the other computers are its clients. If each of the clients
+is configured with the <<local,*local*>> directive, the server can be set up
+with an *initstepslew* directive which references some or all of the clients.
+Then, if the server machine has to be rebooted, the clients can be relied on to
+act analogously to a flywheel and preserve the time for a short period while
+the server completes its reboot.
++
+The *initstepslew* directive is functionally similar to a combination of the
+<<makestep,*makestep*>> and <<server,*server*>> directives with the *iburst*
+option. The main difference is that the *initstepslew* servers are used only
+before normal operation begins and that the foreground *chronyd* process waits
+for *initstepslew* to finish before exiting. This prevent programs started in
+the boot sequence after *chronyd* from reading the clock before it has been
+stepped. With the *makestep* directive, the
+<<chronyc.adoc#waitsync,*waitsync*>> command of *chronyc* can be used instead.
+
+[[refclock]]*refclock* _driver_ _parameter_[:__option__]... [_option_]...::
+The *refclock* directive specifies a hardware reference clock to be used as a
+time source. It has two mandatory parameters, a driver name and a
+driver-specific parameter. The two parameters are followed by zero or more
+refclock options. Some drivers have special options, which can be appended to
+the driver-specific parameter using the *:* character.
++
+This directive can be used multiple times to specify multiple reference clocks.
++
+There are four drivers included in *chronyd*:
++
+*PPS*:::
+Driver for the kernel PPS (pulse per second) API. The parameter is the path to
+the PPS device (typically _/dev/pps?_). As PPS refclocks do not supply full
+time, another time source (e.g. NTP server or non-PPS refclock) is needed to
+complete samples from the PPS refclock. An alternative is to enable the
+<<local,*local*>> directive to allow synchronisation with some unknown but
+constant offset. The driver supports the following option:
++
+*clear*::::
+By default, the PPS refclock uses assert events (rising edge) for
+synchronisation. With this option, it will use clear events (falling edge)
+instead.
++
+{blank}:::
+Examples:
++
+----
+refclock PPS /dev/pps0 lock NMEA refid GPS1
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.2 refid NMEA noselect
+refclock PPS /dev/pps1:clear refid GPS2
+----
++
+*SOCK*:::
+Unix domain socket driver. This driver uses a datagram socket to receive
+samples from another application running on the system. The parameter is the
+path to the socket, which *chronyd* will create on start. The format of the
+messages is described in the _refclock_sock.c_ file in the chrony source code.
++
+An application which supports the SOCK protocol is the *gpsd* daemon. It can
+provide accurate measurements using the receiver's PPS signal, and since
+version 3.25 also (much less accurate) measurements based on the timing of
+serial data (e.g. NMEA), which can be useful when the receiver does not provide
+a PPS signal, or it cannot be connected to the computer. The paths where *gpsd*
+expects the sockets to be created by *chronyd* are described in the *gpsd(8)*
+man page. Note that *gpsd* needs to be started after *chronyd* in order to
+connect to the socket.
++
+Examples:
++
+----
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS1 poll 2 filter 4
+refclock SOCK /var/run/chrony.clk.ttyUSB0.sock refid GPS2 offset 0.2 delay 0.1
+----
++
+*SHM*:::
+NTP shared memory driver. This driver implements the protocol of the *ntpd*
+driver type 28. It is functionally similar to the SOCK driver, but uses a
+shared memory segment instead of a socket. The parameter is the unit number,
+typically a small number like 0, 1, 2, or 3, from which is derived the key of
+the memory segment as 0x4e545030 + unit.
++
+The driver supports the following option:
++
+*perm*=_mode_::::
+This option specifies the permissions of the shared memory segment created by
+*chronyd*. They are specified as a numeric mode. The default value is 0600
+(read-write access for owner only).
+{blank}:::
++
+Unlike with the SOCK driver, there is no prescribed order of starting *chronyd*
+and the program providing measurements. Both are expected to create the memory
+segment if it does not exist. *chronyd* will attach to an existing segment even
+if it has a different owner than root or different permissions than the
+permissions specified by the *perm* option. The segment needs to be created
+before untrusted applications or users can execute code to prevent an attacker
+from feeding *chronyd* with false measurements. The owner and permissions of
+the segment can be verified with the *ipcs -m* command. For this reason, the
+SHM driver is deprecated in favor of SOCK.
++
+Examples:
++
+----
+refclock SHM 0 poll 3 refid GPS1
+refclock SHM 1:perm=0644 refid GPS2
+----
++
+*PHC*:::
+PTP hardware clock (PHC) driver. The parameter is the path to the device of
+the PTP clock which should be used as a time source. If the clock is kept in
+TAI instead of UTC (e.g. it is synchronised by a PTP daemon), the current
+UTC-TAI offset needs to be specified by the *offset* option. Alternatively, the
+*pps* refclock option can be enabled to treat the PHC as a PPS refclock, using
+only the sub-second offset for synchronisation. The driver supports the
+following options:
++
+*nocrossts*::::
+This option disables use of precise cross timestamping.
+*extpps*::::
+This option enables a PPS mode in which the PTP clock is timestamping pulses
+of an external PPS signal connected to the clock. The clock does not need to be
+synchronised, but another time source is needed to complete the PPS samples.
+Note that some PTP clocks cannot be configured to timestamp only assert or
+clear events, and it is necessary to use the *width* option to filter wrong
+PPS samples.
+*pin*=_index_::::
+This option specifies the index of the pin which should be enabled for the
+PPS timestamping. If the PHC does not have configurable pins (i.e. the channel
+function is fixed), the index needs to be set to -1 to disable the pin
+configuration. The default value is 0.
+*channel*=_index_::::
+This option specifies the index of the channel for the PPS mode. The default
+value is 0.
+*clear*::::
+This option enables timestamping of clear events (falling edge) instead of
+assert events (rising edge) in the PPS mode. This may not work with some
+clocks.
+{blank}:::
++
+Examples:
++
+----
+refclock PHC /dev/ptp0 poll 0 dpoll -2 offset -37
+refclock PHC /dev/ptp1:nocrossts poll 3 pps
+refclock PHC /dev/ptp2:extpps:pin=1 width 0.2 poll 2
+----
++
+{blank}::
+The *refclock* directive supports the following options:
++
+*poll* _poll_:::
+Timestamps produced by refclock drivers are not used immediately, but they are
+stored and processed by a median filter in the polling interval specified by
+this option. This is defined as a power of 2 and can be negative to specify a
+sub-second interval. The default is 4 (16 seconds). A shorter interval allows
+*chronyd* to react faster to changes in the frequency of the system clock, but
+it might have a negative effect on its accuracy if the samples have a lot of
+jitter.
+*dpoll* _dpoll_:::
+Some drivers do not listen for external events and try to produce samples in
+their own polling interval. This is defined as a power of 2 and can be negative
+to specify a sub-second interval. The default is 0 (1 second).
+*refid* _refid_:::
+This option is used to specify the reference ID of the refclock, as up to four
+ASCII characters. The default reference ID is composed from the first three
+characters of the driver name and the number of the refclock. Each refclock
+must have a unique reference ID.
+*lock* _refid_:::
+This option can be used to lock a PPS refclock to another refclock, which is
+specified by its reference ID. In this mode received PPS samples are paired
+directly with raw samples from the specified refclock.
+*rate* _rate_:::
+This option sets the rate of the pulses in the PPS signal (in Hz). This option
+controls how the pulses will be completed with real time. To actually receive
+more than one pulse per second, a negative *dpoll* has to be specified (-3 for
+a 5Hz signal). The default is 1.
+*maxlockage* _pulses_:::
+This option specifies in number of pulses how old can be samples from the
+refclock specified by the *lock* option to be paired with the pulses.
+Increasing this value is useful when the samples are produced at a lower rate
+than the pulses. The default is 2.
+*width* _width_:::
+This option specifies the width of the pulses (in seconds). It is used to
+filter PPS samples when the driver provides samples for both rising and falling
+edges. Note that it reduces the maximum allowed error of the time source which
+completes the PPS samples. If the duty cycle is configurable, 50% should be
+preferred in order to maximise the allowed error.
+*pps*:::
+This options forces *chronyd* to treat any refclock (e.g. SHM or PHC) as a PPS
+refclock. This can be useful when the refclock provides time with a variable
+offset of a whole number of seconds (e.g. it uses TAI instead of UTC). Another
+time source is needed to complete samples from the refclock.
+*offset* _offset_:::
+This option can be used to compensate for a constant error. The specified
+offset (in seconds) is applied to all samples produced by the reference clock.
+The default is 0.0.
+*delay* _delay_:::
+This option sets the NTP delay of the source (in seconds). Half of this value
+is included in the maximum assumed error which is used in the source selection
+algorithm. Increasing the delay is useful to avoid having no majority in the
+source selection or to make it prefer other sources. The default is 1e-9 (1
+nanosecond).
+*stratum* _stratum_:::
+This option sets the NTP stratum of the refclock. This can be useful when the
+refclock provides time with a stratum other than 0. The default is 0.
+*precision* _precision_:::
+This option sets the precision of the reference clock (in seconds). The default
+value is the estimated precision of the system clock.
+*maxdispersion* _dispersion_:::
+Maximum allowed dispersion for filtered samples (in seconds). Samples with
+larger estimated dispersion are ignored. By default, this limit is disabled.
+*filter* _samples_:::
+This option sets the length of the median filter which is used to reduce the
+noise in the measurements. With each poll about 40 percent of the stored
+samples are discarded and one final sample is calculated as an average of the
+remaining samples. If the length is 4 or more, at least 4 samples have to be
+collected between polls. For lengths below 4, the filter has to be full. The
+default is 64. With drivers that perform their own polling (PPS, PHC, SHM), the
+maximum value is adjusted to the number of driver polls per source poll, i.e.
+2^(_poll_ - _dpoll_).
+*prefer*:::
+Prefer this source over sources without the prefer option.
+*noselect*:::
+Never select this source. This is useful for monitoring or with sources which
+are not very accurate, but are locked with a PPS refclock.
+*trust*:::
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+*require*:::
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the *trust* option this can be useful to allow a trusted,
+but not very precise, reference clock to be safely combined with
+unauthenticated NTP sources in order to improve the accuracy of the clock. They
+can be selected and used for synchronisation only if they agree with the
+trusted and required source.
+*tai*:::
+This option indicates that the reference clock keeps time in TAI instead of UTC
+and that *chronyd* should correct its offset by the current TAI-UTC offset. The
+<<leapsectz,*leapsectz*>> directive must be used with this option and the
+database must be kept up to date in order for this correction to work as
+expected. This option does not make sense with PPS refclocks.
+*local*:::
+This option specifies that the reference clock is an unsynchronised clock which
+is more stable than the system clock (e.g. TCXO, OCXO, or atomic clock) and
+it should be used as a local standard to stabilise the system clock. The
+refclock will bypass the source selection. There should be at most one refclock
+specified with this option and it should have the shortest polling interval
+among all configured sources.
+*minsamples* _samples_:::
+Set the minimum number of samples kept for this source. This overrides the
+<<minsamples,*minsamples*>> directive.
+*maxsamples* _samples_:::
+Set the maximum number of samples kept for this source. This overrides the
+<<maxsamples,*maxsamples*>> directive.
+
+[[manual]]*manual*::
+The *manual* directive enables support at run-time for the
+<<chronyc.adoc#settime,*settime*>> command in *chronyc*. If no *manual*
+directive is included, any attempt to use the *settime* command in *chronyc*
+will be met with an error message.
++
+Note that the *settime* command can be enabled at run-time using
+the <<chronyc.adoc#manual,*manual*>> command in *chronyc*. (The idea of the two
+commands is that the *manual* command controls the manual clock driver's
+behaviour, whereas the *settime* command allows samples of manually entered
+time to be provided.)
+
+[[acquisitionport]]*acquisitionport* _port_::
+By default, *chronyd* as an NTP client opens a new socket for each request with
+the source port chosen randomly by the operating system. The *acquisitionport*
+directive can be used to specify the source port and use only one socket (per
+IPv4 or IPv6 address family) for all configured servers. This can be useful for
+getting through some firewalls. It should not be used if not necessary as there
+is a small impact on security of the client. If set to 0, the source port of
+the permanent socket will be chosen randomly by the operating system.
++
+It can be set to the same port as is used by the NTP server (which can be
+configured with the <<port,*port*>> directive) to use only one socket for all
+NTP packets.
++
+An example of the *acquisitionport* directive is:
++
+----
+acquisitionport 1123
+----
++
+This would change the source port used for client requests to UDP port 1123.
+You could then persuade the firewall administrator to open that port.
+
+[[bindacqaddress]]*bindacqaddress* _address_::
+The *bindacqaddress* directive specifies a local IP address to which
+*chronyd* will bind its NTP and NTS-KE client sockets. The syntax is similar to
+the <<bindaddress,*bindaddress*>> and <<bindcmdaddress,*bindcmdaddress*>>
+directives.
++
+For each of the IPv4 and IPv6 protocols, only one *bindacqaddress* directive
+can be specified.
+
+[[bindacqdevice]]*bindacqdevice* _interface_::
+The *bindacqdevice* directive binds the client sockets to a network device
+specified by the interface name. This can be useful when the local address is
+dynamic, or to enable an NTP source specified with a link-local IPv6 address.
+This directive can specify only one interface and it is supported on Linux
+only.
++
+An example of the directive is:
++
+----
+bindacqdevice eth0
+----
+
+[[dscp]]*dscp* _point_::
+The *dscp* directive sets the Differentiated Services Code Point (DSCP) in
+transmitted NTP packets to the specified value. It can improve stability of NTP
+measurements in local networks where switches or routers are configured to
+prioritise forwarding of packets with specific DSCP values. The default value
+is 0 and the maximum value is 63.
++
+An example of the directive (setting the Expedited Forwarding class) is:
++
+----
+dscp 46
+----
+
+[[dumpdir]]*dumpdir* _directory_::
+To compute the rate of gain or loss of time, *chronyd* has to store a
+measurement history for each of the time sources it uses.
++
+All supported systems, with the exception of macOS 10.12 and earlier, have
+operating system support for setting the rate of gain or loss to compensate for
+known errors.
+(On macOS 10.12 and earlier, *chronyd* must simulate such a capability by
+periodically slewing the system clock forwards or backwards by a suitable amount
+to compensate for the error built up since the previous slew.)
++
+For such systems, it is possible to save the measurement history across
+restarts of *chronyd* (assuming no changes are made to the system clock
+behaviour whilst it is not running). The *dumpdir* directive defines the
+directory where the measurement histories are saved when *chronyd* exits,
+or the <<chronyc.adoc#dump,*dump*>> command in *chronyc* is issued.
++
+If the directory does not exist, it will be created automatically.
++
+The *-r* option of *chronyd* enables loading of the dump files on start. All
+dump files found in the directory will be removed after start, even if the *-r*
+option is not present.
++
+An example of the directive is:
++
+----
+dumpdir @CHRONYRUNDIR@
+----
++
+A source whose IP address is _1.2.3.4_ would have its measurement history saved
+in the file _@CHRONYRUNDIR@/1.2.3.4.dat_. History of reference clocks is saved
+to files named by their reference ID in form of _refid:XXXXXXXX.dat_.
+
+[[maxsamples]]*maxsamples* _samples_::
+The *maxsamples* directive sets the default maximum number of samples that
+*chronyd* should keep for each source. This setting can be overridden for
+individual sources in the <<server,*server*>> and <<refclock,*refclock*>>
+directives. The default value is 0, which disables the configurable limit. The
+useful range is 4 to 64.
++
+As a special case, setting *maxsamples* to 1 disables frequency tracking in
+order to make the sources immediately selectable with only one sample. This can
+be useful when *chronyd* is started with the *-q* or *-Q* option.
+
+[[minsamples]]*minsamples* _samples_::
+The *minsamples* directive sets the default minimum number of samples that
+*chronyd* should keep for each source. This setting can be overridden for
+individual sources in the <<server,*server*>> and <<refclock,*refclock*>>
+directives. The default value is 6. The useful range is 4 to 64.
++
+Forcing *chronyd* to keep more samples than it would normally keep reduces
+noise in the estimated frequency and offset, but slows down the response to
+changes in the frequency and offset of the clock. The offsets in the
+<<chronyc.adoc#tracking,*tracking*>> and
+<<chronyc.adoc#sourcestats,*sourcestats*>> reports (and the _tracking.log_ and
+_statistics.log_ files) may be smaller than the actual offsets.
+
+[[ntsdumpdir1]]*ntsdumpdir* _directory_::
+This directive specifies a directory for the client to save NTS cookies it
+received from the server in order to avoid making an NTS-KE request when
+*chronyd* is started again. The cookies are saved separately for each NTP
+source in files named by the IP address of the NTS-KE server (e.g.
+_1.2.3.4.nts_). By default, the client does not save the cookies.
++
+If the directory does not exist, it will be created automatically.
++
+An example of the directive is:
++
+----
+ntsdumpdir @CHRONYVARDIR@
+----
++
+This directory is used also by the <<ntsdumpdir2,NTS server>> to save keys.
+
+[[ntsrefresh]]*ntsrefresh* _interval_::
+This directive specifies the maximum interval between NTS-KE handshakes (in
+seconds) in order to refresh the keys authenticating NTP packets. The default
+value is 2419200 (4 weeks) and the maximum value is 2^31-1 (68 years).
++
+The interval must be longer than polling intervals of all configured NTP
+sources using NTS, otherwise the source with a longer polling interval will
+refresh the keys on each poll and no NTP packets will be exchanged.
+
+[[ntstrustedcerts]]*ntstrustedcerts* [_set-ID_] _file_|_directory_::
+This directive specifies a file or directory containing certificates (in the
+PEM format) of trusted certificate authorities (CA) which can be used to
+verify certificates of NTS servers.
++
+The optional _set-ID_ argument is a number in the range 0 through 2^32-1, which
+selects the set of certificates where certificates from the specified file
+or directory are added. The default ID is 0, which is a set containing the
+system's default trusted CAs (unless the *nosystemcert* directive is present).
+All other sets are empty by default. A set of certificates can be selected for
+verification of an NTS server by the *certset* option in the *server* or *pool*
+directive.
++
+This directive can be used multiple times to specify one or more sets of
+trusted certificates, each containing certificates from one or more files
+and/or directories.
++
+It is not necessary to restart *chronyd* in order to reload the certificates if
+they change (e.g. after a renewal).
++
+An example is:
++
+----
+ntstrustedcerts /etc/pki/nts/foo.crt
+ntstrustedcerts 1 /etc/pki/nts/bar.crt
+ntstrustedcerts 1 /etc/pki/nts/baz.crt
+ntstrustedcerts 2 /etc/pki/nts/qux.crt
+----
+
+[[nosystemcert]]*nosystemcert*::
+This directive disables the system's default trusted CAs. Only certificates
+specified by the *ntstrustedcerts* directive will be trusted.
+
+[[nocerttimecheck]]*nocerttimecheck* _limit_::
+This directive disables the checks of the activation and expiration times of
+certificates for the specified number of clock updates. It allows the NTS
+authentication mechanism to be used on computers which start with wrong time
+(e.g. due to not having an RTC or backup battery). Disabling the time checks
+has important security implications and should be used only as a last resort,
+preferably with a minimal number of trusted certificates. The default value is
+0, which means the time checks are always enabled.
++
+An example of the directive is:
++
+----
+nocerttimecheck 1
+----
++
+This would disable the time checks until the clock is updated for the first
+time, assuming the first update corrects the clock and later checks can work
+with correct time.
+
+[[refresh]]*refresh* _interval_::
+This directive specifies the interval (in seconds) between refreshing IP
+addresses of NTP sources specified by hostname. If the hostname no longer
+resolves to the currently used address, it will be replaced with one of the new
+addresses to avoid using a server which is no longer intended for service, even
+if it is still responding correctly and would not be replaced as unreachable.
+Only one source is refreshed at a time. The default value is 1209600 (2 weeks)
+and the maximum value is 2^31-1 (68 years). A value of 0 disables the periodic
+refreshment.
++
+The <<chronyc.adoc#refresh,*refresh*>> command can be used to refresh all
+sources immediately.
+
+=== Source selection
+
+[[authselectmode]]*authselectmode* _mode_::
+NTP sources can be specified with the *key* or *nts* option to enable
+authentication to limit the impact of man-in-the-middle attacks. The
+attackers can drop or delay NTP packets (up to the *maxdelay* and
+<<maxdistance,*maxdistance*>> limits), but they cannot modify the timestamps
+contained in the packets. The attack can cause only a limited slew or step, and
+also cause the clock to run faster or slower than real time (up to double of
+the <<maxdrift,*maxdrift*>> limit).
++
+When authentication is enabled for an NTP source, it is important to disable
+unauthenticated NTP sources which could be exploited in the attack, e.g. if
+they are not reachable only over a trusted network. Alternatively, the source
+selection can be configured with the *require* and *trust* options to
+synchronise to the unauthenticated sources only if they agree with the
+authenticated sources and might have a positive impact on the accuracy of the
+clock. Note that in this case the impact of the attack is higher. The attackers
+cannot cause an arbitrarily large step or slew, but they have more control over
+the frequency of the clock and can cause *chronyd* to report false information,
+e.g. a significantly smaller root delay and dispersion.
++
+This directive determines the default selection options for authenticated and
+unauthenticated sources in order to simplify the configuration with the
+configuration file and *chronyc* commands. It sets a policy for authentication.
++
+Sources specified with the *noselect* option are ignored (not counted as either
+authenticated or unauthenticated), and they always have only the selection
+options specified in the configuration.
++
+There are four modes:
++
+*require*:::
+Authentication is strictly required for NTP sources in this mode. If any
+unauthenticated NTP sources are specified, they will automatically get the
+*noselect* option to prevent them from being selected for synchronisation.
+*prefer*:::
+In this mode, authentication is optional and preferred. If it is enabled for at
+least one NTP source, all unauthenticated NTP sources will get the *noselect*
+option.
+*mix*:::
+In this mode, authentication is optional and synchronisation to a mix of
+authenticated and unauthenticated NTP sources is allowed. If both authenticated
+and unauthenticated NTP sources are specified, all authenticated NTP sources
+and reference clocks will get the *require* and *trust* options to prevent
+synchronisation to unauthenticated NTP sources if they do not agree with a
+majority of the authenticated sources and reference clocks. This is the default
+mode.
+*ignore*:::
+In this mode, authentication is ignored in the source selection. All sources
+will have only the selection options that were specified in the configuration
+file, or *chronyc* command. This was the behaviour of *chronyd* in versions
+before 4.0.
+{blank}::
++
+As an example, the following configuration using the default *mix* mode:
++
+----
+server foo.example.net nts
+server bar.example.net nts
+server baz.example.net
+refclock SOCK /var/run/chrony.ttyS0.sock
+----
++
+is equivalent to the following configuration using the *ignore* mode:
++
+----
+authselectmode ignore
+server foo.example.net nts require trust
+server bar.example.net nts require trust
+server baz.example.net
+refclock /var/run/chrony.ttyS0.sock require trust
+----
+
+[[combinelimit]]*combinelimit* _limit_::
+When *chronyd* has multiple sources available for synchronisation, it has to
+select one source as the synchronisation source. The measured offsets and
+frequencies of the system clock relative to the other sources, however, can be
+combined with the selected source to improve the accuracy of the system clock.
++
+The *combinelimit* directive limits which sources are included in the combining
+algorithm. Their synchronisation distance has to be shorter than the distance
+of the selected source multiplied by the value of the limit. Also, their
+measured frequencies have to be close to the frequency of the selected source.
+If the selected source was specified with the *prefer* option, it can be
+combined only with other sources specified with this option.
++
+By default, the limit is 3. Setting the limit to 0 effectively disables the
+source combining algorithm and only the selected source will be used to control
+the system clock.
+
+[[maxdistance]]*maxdistance* _distance_::
+The *maxdistance* directive sets the maximum root distance of a source to be
+acceptable for synchronisation of the clock. Sources that have a distance
+larger than the specified distance will be rejected. The distance estimates the
+maximum error of the source. It includes the root dispersion and half of the
+root delay (round-trip time) accumulated on the path to the primary source.
++
+By default, the maximum root distance is 3 seconds.
++
+Setting *maxdistance* to a larger value can be useful to allow synchronisation
+with a server that only has a very infrequent connection to its sources and can
+accumulate a large dispersion between updates of its clock.
+
+[[maxjitter]]*maxjitter* _jitter_::
+The *maxjitter* directive sets the maximum allowed jitter of the sources to not
+be rejected by the source selection algorithm. This prevents synchronisation
+with sources that have a small root distance, but their time is too variable.
++
+By default, the maximum jitter is 1 second.
+
+[[minsources]]*minsources* _sources_::
+The *minsources* directive sets the minimum number of sources that need to be
+considered as selectable in the source selection algorithm before the local
+clock is updated. The default value is 1.
++
+Setting this option to a larger number can be used to improve the reliability.
+More sources will have to agree with each other and the clock will not be
+updated when only one source (which could be serving incorrect time) is
+reachable.
+
+[[reselectdist]]*reselectdist* _distance_::
+When *chronyd* selects a synchronisation source from available sources, it
+will prefer the one with the shortest synchronisation distance. However, to
+avoid frequent reselecting when there are sources with similar distance, a
+fixed distance is added to the distance for sources that are currently not
+selected. This can be set with the *reselectdist* directive. By default, the
+distance is 100 microseconds.
+
+[[stratumweight]]*stratumweight* _distance_::
+The *stratumweight* directive sets how much distance should be added per
+stratum to the synchronisation distance when *chronyd* selects the
+synchronisation source from available sources.
++
+By default, the weight is 0.001 seconds. This means that the stratum of the sources
+in the selection process matters only when the differences between the
+distances are in milliseconds.
+
+=== System clock
+
+[[clockprecision]]*clockprecision* _precision_::
+The *clockprecision* directive specifies the precision of the system clock (in
+seconds). It is used by *chronyd* to estimate the minimum noise in NTP
+measurements and randomise low-order bits of timestamps in NTP responses. By
+default, the precision is measured on start as the minimum time to read the
+clock.
++
+The measured value works well in most cases. However, it generally
+overestimates the precision and it can be sensitive to the CPU speed, which can
+change over time to save power. In some cases with a high-precision clocksource
+(e.g. the Time Stamp Counter of the CPU) and hardware timestamping, setting the
+precision on the server to a smaller value can improve stability of clients'
+NTP measurements. The server's precision is reported on clients by the
+<<chronyc.adoc#ntpdata,*ntpdata*>> command.
++
+An example setting the precision to 8 nanoseconds is:
++
+----
+clockprecision 8e-9
+----
+
+[[corrtimeratio]]*corrtimeratio* _ratio_::
+When *chronyd* is slewing the system clock to correct an offset, the rate at
+which it is slewing adds to the frequency error of the clock. On all supported
+systems, with the exception of macOS 12 and earlier, this rate can be
+controlled.
++
+The *corrtimeratio* directive sets the ratio between the duration in which the
+clock is slewed for an average correction according to the source history and
+the interval in which the corrections are done (usually the NTP polling
+interval). Corrections larger than the average take less time and smaller
+corrections take more time, the amount of the correction and the correction
+time are inversely proportional.
++
+Increasing *corrtimeratio* improves the overall frequency error of the system
+clock, but increases the overall time error as the corrections take longer.
++
+By default, the ratio is set to 3, the time accuracy of the clock is preferred
+over its frequency accuracy.
++
+The maximum allowed slew rate can be set by the <<maxslewrate,*maxslewrate*>>
+directive. The current remaining correction is shown in the
+<<chronyc.adoc#tracking,*tracking*>> report as the *System time* value.
+
+[[driftfile]]*driftfile* _file_::
+One of the main activities of the *chronyd* program is to work out the rate at
+which the system clock gains or loses time relative to real time.
++
+Whenever *chronyd* computes a new value of the gain or loss rate, it is desirable
+to record it somewhere. This allows *chronyd* to begin compensating the system
+clock at that rate whenever it is restarted, even before it has had a chance to
+obtain an equally good estimate of the rate during the new run. (This process
+can take many minutes, at least.)
++
+The *driftfile* directive allows a file to be specified into which *chronyd*
+can store the rate information. Two parameters are recorded in the file. The
+first is the rate at which the system clock gains or loses time, expressed in
+parts per million, with gains positive. Therefore, a value of 100.0 indicates
+that when the system clock has advanced by a second, it has gained 100
+microseconds in reality (so the true time has only advanced by 999900
+microseconds). The second is an estimate of the error bound around the first
+value in which the true rate actually lies.
++
+An example of the driftfile directive is:
++
+----
+driftfile @CHRONYVARDIR@/drift
+----
+
+[[fallbackdrift]]*fallbackdrift* _min-interval_ _max-interval_::
+Fallback drifts are long-term averages of the system clock drift calculated
+over exponentially increasing intervals. They are used to avoid quickly
+drifting away from true time when the clock was not updated for a longer period
+of time and there was a short-term deviation in the drift before the updates
+stopped.
++
+The directive specifies the minimum and maximum interval since the last clock
+update to switch between fallback drifts. They are defined as a power of 2 (in
+seconds). The syntax is as follows:
++
+----
+fallbackdrift 16 19
+----
++
+In this example, the minimum interval is 16 (18 hours) and the maximum interval is
+19 (6 days). The system clock frequency will be set to the first fallback 18
+hours after last clock update, to the second after 36 hours, and so on. This
+might be a good setting to cover frequency changes due to daily and weekly
+temperature fluctuations. When the frequency is set to a fallback, the state of
+the clock will change to '`Not synchronised`'.
++
+By default (or if the specified maximum or minimum is 0), no fallbacks are used
+and the clock frequency changes only with new measurements from NTP sources,
+reference clocks, or manual input.
+
+[[leapsecmode]]*leapsecmode* _mode_::
+A leap second is an adjustment that is occasionally applied to UTC to keep it
+close to the mean solar time. When a leap second is inserted, the last day of
+June or December has an extra second 23:59:60.
++
+For computer clocks that is a problem. The Unix time is defined as number of
+seconds since 00:00:00 UTC on 1 January 1970 without leap seconds. The system
+clock cannot have time 23:59:60, every minute has 60 seconds and every day has
+86400 seconds by definition. The inserted leap second is skipped and the clock
+is suddenly ahead of UTC by one second. The *leapsecmode* directive selects how
+that error is corrected. There are four options:
++
+*system*:::
+When inserting a leap second, the kernel steps the system clock backwards by
+one second when the clock gets to 00:00:00 UTC. When deleting a leap second, it
+steps forward by one second when the clock gets to 23:59:59 UTC. This is the
+default mode when the system driver supports leap seconds (i.e. all supported
+systems with the exception of macOS 12 and earlier).
+*step*:::
+This is similar to the *system* mode, except the clock is stepped by
+*chronyd* instead of the kernel. It can be useful to avoid bugs in the kernel
+code that would be executed in the *system* mode. This is the default mode
+when the system driver does not support leap seconds.
+*slew*:::
+The clock is corrected by slewing started at 00:00:00 UTC when a leap second
+is inserted or 23:59:59 UTC when a leap second is deleted. This might be
+preferred over the *system* and *step* modes when applications running on the
+system are sensitive to jumps in the system time and it is acceptable that the
+clock will be off for a longer time. On Linux with the default
+<<maxslewrate,*maxslewrate*>> value the correction takes 12 seconds.
+*ignore*:::
+No correction is applied to the clock for the leap second. The clock will be
+corrected later in normal operation when new measurements are made and the
+estimated offset includes the one second error. This option is particularly
+useful when multiple *chronyd* instances are running on the system, one
+controlling the system clock and others started with the *-x* option, which
+should rely on the first instance to correct the system clock and ignore it for
+the correction of their own NTP clock running on top of the system clock.
+{blank}::
++
+When serving time to NTP clients that cannot be configured to correct their
+clocks for a leap second by slewing, or to clients that would correct at
+slightly different rates when it is necessary to keep them close together, the
+*slew* mode can be combined with the <<smoothtime,*smoothtime*>> directive to
+enable a server leap smear.
++
+When smearing a leap second, the leap status is suppressed on the server and
+the served time is corrected slowly by slewing instead of stepping. The clients
+do not need any special configuration as they do not know there is any leap
+second and they follow the server time which eventually brings them back to
+UTC. Care must be taken to ensure they use only NTP servers which smear the
+leap second in exactly the same way for synchronisation.
++
+This feature must be used carefully, because the server is intentionally not
+serving its best estimate of the true time.
++
+A recommended configuration to enable a server leap smear is:
++
+----
+leapsecmode slew
+maxslewrate 1000
+smoothtime 400 0.001024 leaponly
+----
++
+The first directive is necessary to disable the clock step which would reset
+the smoothing process. The second directive limits the slewing rate of the
+local clock to 1000 ppm, which improves the stability of the smoothing process
+when the local correction starts and ends. The third directive enables the
+server time smoothing process. It will start when the clock gets to 00:00:00
+UTC and it will take 62500 seconds (about 17.36 hours) to finish. The frequency
+offset will be changing by 0.001024 ppm per second and will reach a maximum of
+32 ppm in 31250 seconds. The *leaponly* option makes the duration of the leap
+smear constant and allows the clients to safely synchronise with multiple
+identically configured leap smearing servers.
++
+The duration of the leap smear can be calculated from the specified wander as
++
+----
+duration = sqrt(4 / wander)
+----
+
+[[leapsectz]]*leapsectz* _timezone_::
+This directive specifies a timezone in the system timezone database which
+*chronyd* can use to determine when will the next leap second occur and what is
+the current offset between TAI and UTC. It will periodically check if 23:59:59
+and 23:59:60 are valid times in the timezone. This normally works with the
+_right/UTC_ timezone.
++
+When a leap second is announced, the timezone needs to be updated at least 12
+hours before the leap second. It is not necessary to restart *chronyd*.
++
+This directive is useful with reference clocks and other time sources which do
+not announce leap seconds, or announce them too late for an NTP server to
+forward them to its own clients. Clients of leap smearing servers must not
+use this directive.
++
+It is also useful when the system clock is required to have correct TAI-UTC
+offset. Note that the offset is set only when leap seconds are handled by the
+kernel, i.e. <<leapsecmode,*leapsecmode*>> is set to *system*.
++
+The specified timezone is not used as an exclusive source of information about
+leap seconds. If a majority of time sources announce on the last day of June or
+December that a leap second should be inserted or deleted, it will be accepted
+even if it is not included in the timezone.
++
+An example of the directive is:
++
+----
+leapsectz right/UTC
+----
++
+The following shell command verifies that the timezone contains leap seconds
+and can be used with this directive:
++
+----
+$ TZ=right/UTC date -d 'Dec 31 2008 23:59:60'
+Wed Dec 31 23:59:60 UTC 2008
+----
+
+[[makestep]]*makestep* _threshold_ _limit_::
+Normally *chronyd* will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+e.g. when *chronyd* is initially started, the system clock might be so far
+adrift that this slewing process would take a very long time to correct the
+system clock.
++
+This directive forces *chronyd* to step the system clock if the adjustment is
+larger than a threshold value, but only if there were no more clock updates
+since *chronyd* was started than the specified limit. A negative value disables
+the limit.
++
+On most systems it is desirable to step the system clock only on boot, before
+starting programs that rely on time advancing monotonically forwards.
++
+An example of the use of this directive is:
++
+----
+makestep 0.1 3
+----
++
+This would step the system clock if the adjustment is larger than 0.1 seconds, but
+only in the first three clock updates.
+
+[[maxchange]]*maxchange* _offset_ _start_ _ignore_::
+This directive sets the maximum offset to be accepted on a clock update. The
+offset is measured relative to the current estimate of the true time, which is
+different from the system time if a previous slew did not finish.
++
+The check is enabled after the specified number of clock updates to allow a
+large initial offset to be corrected on start. Offsets larger than the
+specified maximum will be ignored for the specified number of times. Another
+large offset will cause *chronyd* to give up and exit. A negative value
+can be used to disable the limit to ignore all large offsets. A syslog message
+will be generated when an offset is ignored or it causes the exit.
++
+An example of the use of this directive is:
++
+----
+maxchange 1000 1 2
+----
++
+After the first clock update, *chronyd* will check the offset on every clock
+update, it will ignore two adjustments larger than 1000 seconds and exit on
+another one.
+
+[[maxclockerror]]*maxclockerror* _error-in-ppm_::
+The *maxclockerror* directive sets the maximum assumed frequency error that the
+system clock can gain on its own between clock updates. It describes the
+stability of the clock.
++
+By default, the maximum error is 1 ppm.
++
+Typical values for _error-in-ppm_ might be 10 for a low quality clock and 0.1
+for a high quality clock using a temperature compensated crystal oscillator.
+
+[[maxdrift]]*maxdrift* _drift-in-ppm_::
+This directive specifies the maximum assumed drift (frequency error) of the
+system clock. It limits the frequency adjustment that *chronyd* is allowed to
+use to correct the measured drift. It is an additional limit to the maximum
+adjustment that can be set by the system driver (100000 ppm on Linux, 500 ppm
+on FreeBSD, NetBSD, and macOS 10.13+, 32500 ppm on illumos).
++
+By default, the maximum assumed drift is 500000 ppm, i.e. the adjustment is
+limited by the system driver rather than this directive.
+
+[[maxupdateskew]]*maxupdateskew* _skew-in-ppm_::
+One of *chronyd*'s tasks is to work out how fast or slow the computer's clock
+runs relative to its reference sources. In addition, it computes an estimate of
+the error bounds around the estimated value.
++
+If the range of error is too large, it probably indicates that the measurements
+have not settled down yet, and that the estimated gain or loss rate is not very
+reliable.
++
+The *maxupdateskew* directive sets the threshold for determining whether an
+estimate might be so unreliable that it should not be used. By default, the
+threshold is 1000 ppm.
++
+Typical values for _skew-in-ppm_ might be 100 for NTP sources polled over a
+wireless network, and 10 or smaller for sources on a local wired network.
++
+It should be noted that this is not the only means of protection against using
+unreliable estimates. At all times, *chronyd* keeps track of both the estimated
+gain or loss rate, and the error bound on the estimate. When a new estimate is
+generated following another measurement from one of the sources, a weighted
+combination algorithm is used to update the existing estimate. If it has
+significantly smaller error bounds than the new estimate, the existing estimate
+will dominate in the new combined value.
+
+[[maxslewrate]]*maxslewrate* _rate-in-ppm_::
+The *maxslewrate* directive sets the maximum rate at which *chronyd* is allowed
+to slew the time. It limits the slew rate controlled by the correction time
+ratio (which can be set by the <<corrtimeratio,*corrtimeratio*>> directive) and
+is effective only on systems where *chronyd* is able to control the rate (i.e.
+all supported systems with the exception of macOS 12 or earlier).
++
+For each system there is a maximum frequency offset of the clock that can be set
+by the driver. On Linux it is 100000 ppm, on FreeBSD, NetBSD and macOS 10.13+ it
+is 5000 ppm, and on illumos it is 32500 ppm. Also, due to a kernel limitation,
+setting *maxslewrate* on FreeBSD, NetBSD, macOS 10.13+ to a value between 500
+ppm and 5000 ppm will effectively set it to 500 ppm.
++
+By default, the maximum slew rate is set to 83333.333 ppm (one twelfth).
+
+[[tempcomp]]
+*tempcomp* _file_ _interval_ _T0_ _k0_ _k1_ _k2_::
+*tempcomp* _file_ _interval_ _points-file_::
+Normally, changes in the rate of drift of the system clock are caused mainly by
+changes in the temperature of the crystal oscillator on the motherboard.
++
+If there are temperature measurements available from a sensor close to the
+oscillator, the *tempcomp* directive can be used to compensate for the changes
+in the temperature and improve the stability and accuracy of the clock.
++
+The result depends on many factors, including the resolution of the sensor, the
+amount of noise in the measurements, the polling interval of the time source,
+the compensation update interval, how well the compensation is specified, and
+how close the sensor is to the oscillator. When it is working well, the
+frequency reported in the _tracking.log_ file is more stable and the maximum
+reached offset is smaller.
++
+There are two forms of the directive. The first one has six parameters: a path
+to the file containing the current temperature from the sensor (in text
+format), the compensation update interval (in seconds), and temperature
+coefficients _T0_, _k0_, _k1_, _k2_.
++
+The frequency compensation is calculated (in ppm) as
++
+----
+comp = k0 + (T - T0) * k1 + (T - T0)^2 * k2
+----
++
+The result has to be between -10 ppm and 10 ppm, otherwise the measurement is
+considered invalid and will be ignored. The _k0_ coefficient can be adjusted to
+keep the compensation in that range.
++
+An example of the use is:
++
+----
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 26000 0.0 0.000183 0.0
+----
++
+The measured temperature will be read from the file in the Linux sysfs
+filesystem every 30 seconds. When the temperature is 26000 (26 degrees
+Celsius), the frequency correction will be zero. When it is 27000 (27 degrees
+Celsius), the clock will be set to run faster by 0.183 ppm, etc.
++
+The second form has three parameters: the path to the sensor file, the update
+interval, and a path to a file containing a list of (temperature, compensation)
+points, from which the compensation is linearly interpolated or extrapolated.
++
+An example is:
++
+----
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 /etc/chrony.tempcomp
+----
++
+where the _/etc/chrony.tempcomp_ file could have
++
+----
+20000 1.0
+21000 0.64
+22000 0.36
+23000 0.16
+24000 0.04
+25000 0.0
+26000 0.04
+27000 0.16
+28000 0.36
+29000 0.64
+30000 1.0
+----
++
+Valid measurements with corresponding compensations are logged to the
+_tempcomp.log_ file if enabled by the <<log,*log tempcomp*>> directive.
+
+=== NTP server
+
+[[allow]]*allow* [*all*] [_subnet_]::
+The *allow* directive is used to designate a particular subnet from which NTP
+clients are allowed to access the computer as an NTP server. It also controls
+access of NTS-KE clients when NTS is enabled on the server.
++
+The default is that no clients are allowed access, i.e. *chronyd* operates
+purely as an NTP client. If the *allow* directive is used, *chronyd* will be
+both a client of its servers, and a server to other clients.
++
+This directive can be used multiple times.
++
+Examples of the use of the directive are as follows:
++
+----
+allow 1.2.3.4
+allow 3.4.5.0/24
+allow 3.4.5
+allow 2001:db8::/32
+allow 0/0
+allow ::/0
+allow
+----
++
+The first directive allows access from an IPv4 address. The second directive
+allows access from all computers in an IPv4 subnet specified in the CIDR
+notation. The third directive specifies the same subnet using a simpler
+notation where the prefix length is determined by the number of dots. The
+fourth directive specifies an IPv6 subnet. The fifth and sixth directives allow
+access from all IPv4 and IPv6 addresses respectively. The seventh directive
+allows access from all addresses (both IPv4 or IPv6).
++
+A second form of the directive, *allow all*, has a greater effect, depending on
+the ordering of directives in the configuration file. To illustrate the effect,
+consider the two examples:
++
+----
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow 1.2.0.0/16
+----
++
+and
++
+----
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow all 1.2.0.0/16
+----
++
+In the first example, the effect is the same regardless of what order the three
+directives are given in. So the _1.2.0.0/16_ subnet is allowed access, except
+for the _1.2.3.0/24_ subnet, which is denied access, however the host _1.2.3.4_
+is allowed access.
++
+In the second example, the *allow all 1.2.0.0/16* directive overrides the
+effect of _any_ previous directive relating to a subnet within the specified
+subnet. Within a configuration file this capability is probably rather moot;
+however, it is of greater use for reconfiguration at run-time via *chronyc*
+with the <<chronyc.adoc#allow,*allow all*>> command.
++
+The rules are internally represented as a tree of tables with one level per
+four bits of the IPv4 or IPv6 address. The order of the *allow* and *deny*
+directives matters if they modify the same records of one table, i.e. if one
+subnet is included in the other subnet and their prefix lengths are at the same
+level. For example, _1.2.3.0/28_ and _1.2.3.0/29_ are in different tables, but
+_1.2.3.0/25_ and _1.2.3.0/28_ are in the same table. The configuration can be
+verified for individual addresses with the <<chronyc.adoc#accheck,*accheck*>>
+command in *chronyc*.
++
+A hostname can be specified in the directives instead of the IP address, but
+the name must be resolvable when *chronyd* is started, i.e. the network is
+already up and DNS is working. If the hostname resolves to multiple addresses,
+only the first address (in the order returned by the system resolver) will be
+allowed or denied.
++
+Note, if the <<initstepslew,*initstepslew*>> directive is used in the
+configuration file, each of the computers listed in that directive must allow
+client access by this computer for it to work.
+
+[[deny]]*deny* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> directive, except that it denies NTP
+and NTS-KE client access to a particular subnet or host, rather than allowing
+it.
++
+The syntax is identical and the directive can be used multiple times too.
++
+There is also a *deny all* directive with similar behaviour to the *allow all*
+directive.
+
+[[bindaddress]]*bindaddress* _address_::
+The *bindaddress* directive binds the sockets on which *chronyd* listens for
+NTP and NTS-KE requests to a local address of the computer. On systems other
+than Linux, the address of the computer needs to be already configured when
+*chronyd* is started.
++
+An example of the use of the directive is:
++
+----
+bindaddress 192.168.1.1
+----
++
+Currently, for each of the IPv4 and IPv6 protocols, only one *bindaddress*
+directive can be specified. Therefore, it is not useful on computers which
+should serve NTP on multiple network interfaces.
+
+[[binddevice]]*binddevice* _interface_::
+The *binddevice* directive binds the NTP and NTS-KE server sockets to a network
+device specified by the interface name. This directive can specify only one
+interface and it is supported on Linux only.
++
+An example of the directive is:
++
+----
+binddevice eth0
+----
+
+[[broadcast]]*broadcast* _interval_ _address_ [_port_]::
+The *broadcast* directive is used to declare a broadcast address to which
+chronyd should send packets in the NTP broadcast mode (i.e. make *chronyd* act
+as a broadcast server). Broadcast clients on that subnet will be able to
+synchronise.
++
+This directive can be used multiple times to specify multiple addresses.
++
+The syntax is as follows:
++
+----
+broadcast 32 192.168.1.255
+broadcast 64 192.168.2.255 12123
+broadcast 64 ff02::101
+----
++
+In the first example, the destination port defaults to UDP port 123 (the normal NTP
+port). In the second example, the destination port is specified as 12123. The
+first parameter in each case (32 or 64 respectively) is the interval in seconds
+between broadcast packets being sent. The second parameter in each case is the
+broadcast address to send the packet to. This should correspond to the
+broadcast address of one of the network interfaces on the computer where
+*chronyd* is running.
++
+You can have more than 1 *broadcast* directive if you have more than 1 network
+interface onto which you want to send NTP broadcast packets.
++
+*chronyd* itself cannot act as a broadcast client; it must always be configured
+as a point-to-point client by defining specific NTP servers and peers. This
+broadcast server feature is intended for providing a time source to other NTP
+implementations.
++
+If *ntpd* is used as the broadcast client, it will try to measure the
+round-trip delay between the server and client with normal client mode packets.
+Thus, the broadcast subnet should also be the subject of an <<allow,*allow*>>
+directive.
+
+[[clientloglimit]]*clientloglimit* _limit_::
+This directive specifies the maximum amount of memory that *chronyd* is allowed
+to allocate for logging of client accesses and the state that *chronyd* as an
+NTP server needs to support the interleaved mode for its clients. The default
+limit is 524288 bytes, which enables monitoring of up to 4096 IP addresses at
+the same time and holding NTP timestamps for up to 4096 clients using the
+interleaved mode (depending on uniformity of their polling interval). The
+number of addresses and timestamps is always a power of 2. The maximum
+effective value is 2147483648 (2 GB), which corresponds to 16777216 addresses
+and timestamps.
++
+An example of the use of this directive is:
++
+----
+clientloglimit 1048576
+----
+
+[[noclientlog]]*noclientlog*::
+This directive, which takes no arguments, specifies that client accesses are
+not to be logged. Normally they are logged, allowing statistics to be reported
+using the <<chronyc.adoc#clients,*clients*>> command in *chronyc*. This option
+also effectively disables server support for the NTP interleaved mode.
+
+[[local]]*local* [_option_]...::
+The *local* directive enables a local reference mode, which allows *chronyd*
+operating as an NTP server to appear synchronised to real time (from the
+viewpoint of clients polling it), even when it was never synchronised or
+the last update of the clock happened a long time ago.
++
+This directive is normally used in an isolated network, where computers are
+required to be synchronised to one another, but not necessarily to real time.
+The server can be kept vaguely in line with real time by manual input.
++
+The *local* directive has the following options:
++
+*stratum* _stratum_:::
+This option sets the stratum of the server which will be reported to clients
+when the local reference is active. The specified value is in the range 1
+through 15, and the default value is 10. It should be larger than the maximum
+expected stratum in the network when external NTP servers are accessible.
++
+Stratum 1 indicates a computer that has a true real-time reference directly
+connected to it (e.g. GPS, atomic clock, etc.), such computers are expected to
+be very close to real time. Stratum 2 computers are those which have a stratum
+1 server; stratum 3 computers have a stratum 2 server and so on. A value
+of 10 indicates that the clock is so many hops away from a reference clock that
+its time is fairly unreliable.
+*distance* _distance_:::
+This option sets the threshold for the root distance which will activate the local
+reference. If *chronyd* was synchronised to some source, the local reference
+will not be activated until its root distance reaches the specified value (the
+rate at which the distance is increasing depends on how well the clock was
+tracking the source). The default value is 1 second.
++
+The current root distance can be calculated from root delay and root dispersion
+(reported by the <<chronyc.adoc#tracking,*tracking*>> command in *chronyc*) as:
++
+----
+distance = delay / 2 + dispersion
+----
+*orphan*:::
+This option enables a special '`orphan`' mode, where sources with stratum equal
+to the local _stratum_ are assumed to not serve real time. They are ignored
+unless no other source is selectable and their reference IDs are smaller than
+the local reference ID.
++
+This allows multiple servers in the network to use the same *local*
+configuration and to be synchronised to one another, without confusing clients
+that poll more than one server. Each server needs to be configured to poll all
+other servers with the *local* directive. This ensures only the server with the
+smallest reference ID has the local reference active and others are
+synchronised to it. If that server stops responding, the server with the second
+smallest reference ID will take over when its local reference mode activates
+(root distance reaches the threshold configured by the *distance* option).
++
+The *orphan* mode is compatible with the *ntpd*'s orphan mode (enabled by the
+*tos orphan* command).
+{blank}::
++
+An example of the directive is:
++
+----
+local stratum 10 orphan distance 0.1
+----
+
+[[ntpsigndsocket]]*ntpsigndsocket* _directory_::
+This directive specifies the location of the Samba *ntp_signd* socket when it
+is running as a Domain Controller (DC). If *chronyd* is compiled with this
+feature, responses to MS-SNTP clients will be signed by the *smbd* daemon.
++
+Note that MS-SNTP requests are not authenticated and any client that is allowed
+to access the server by the <<allow,*allow*>> directive, or the
+<<chronyc.adoc#allow,*allow*>> command in *chronyc*, can get an MS-SNTP
+response signed with a trust account's password and try to crack the password
+in a brute-force attack. Access to the server should be carefully controlled.
++
+An example of the directive is:
++
+----
+ntpsigndsocket /var/lib/samba/ntp_signd
+----
+
+[[ntsport]]*ntsport* _port_::
+This directive specifies the TCP port on which *chronyd* will provide the NTS
+Key Establishment (NTS-KE) service. The default port is 4460.
++
+The port will be open only when a certificate and key is specified by the
+*ntsservercert* and *ntsserverkey* directives.
+
+[[ntsservercert]]*ntsservercert* _file_::
+This directive specifies a file containing a certificate in the PEM format
+for *chronyd* to operate as an NTS server. The file should also include
+any intermediate certificates that the clients will need to validate the
+server's certificate. The file needs to be readable by the user under which
+*chronyd* is running after dropping root privileges.
++
+This directive can be used multiple times to specify multiple certificates for
+different names of the server.
++
+The files are loaded only once. *chronyd* needs to be restarted in order to
+load a renewed certificate. The <<ntsdumpdir,*ntsdumpdir*>> and
+<<dumpdir,*dumpdir*>> directives with the *-r* option of *chronyd* are
+recommended for a near-seamless server operation.
+
+[[ntsserverkey]]*ntsserverkey* _file_::
+This directive specifies a file containing a private key in the PEM format
+for *chronyd* to operate as an NTS server. The file needs to be readable by
+the user under which *chronyd* is running after dropping root privileges. For
+security reasons, it should not be readable by other users.
++
+This directive can be used multiple times to specify multiple keys. The number
+of keys must be the same as the number of certificates and the corresponding
+files must be specified in the same order.
+
+[[ntsprocesses]]*ntsprocesses* _processes_::
+This directive specifies how many helper processes will *chronyd* operating
+as an NTS server start for handling client NTS-KE requests in order to improve
+performance with multi-core CPUs and multithreading. If set to 0, no helper
+process will be started and all NTS-KE requests will be handled by the main
+*chronyd* process. The default value is 1.
+
+[[maxntsconnections]]*maxntsconnections* _connections_::
+This directive specifies the maximum number of concurrent NTS-KE connections
+per process that the NTS server will accept. The default value is 100. The
+maximum practical value is half of the system *FD_SETSIZE* constant (usually
+1024).
+
+[[ntsdumpdir2]]*ntsdumpdir* _directory_::
+This directive specifies a directory where *chronyd* operating as an NTS server
+can save the keys which encrypt NTS cookies provided to clients. The keys are
+saved to a single file named _ntskeys_. When *chronyd* is restarted, reloading
+the keys allows the clients to continue using old cookies and avoids a storm of
+NTS-KE requests. By default, the server does not save the keys.
++
+An example of the directive is:
++
+----
+ntsdumpdir @CHRONYVARDIR@
+----
++
+This directory is used also by the <<ntsdumpdir1,NTS client>> to save NTS cookies.
+
+[[ntsntpserver]]*ntsntpserver* _hostname_::
+This directive specifies the hostname (as a fully qualified domain name) or
+address of the NTP server(s) which is
+provided in the NTS-KE response to the clients. It allows the NTS-KE server to
+be separated from the NTP server. However, the servers need to share the keys,
+i.e. external key management needs to be enabled by setting
+<<ntsrotate,*ntsrotate*>> to 0. By default, no hostname or address is provided
+to the clients, which means they should use the same server for NTS-KE and NTP.
+
+[[ntsrotate]]*ntsrotate* _interval_::
+This directive specifies the rotation interval (in seconds) of the server key
+which encrypts the NTS cookies. New keys are generated automatically from the
+_/dev/urandom_ device. The server keeps two previous keys to give the clients
+time to get new cookies encrypted by the latest key. The interval is measured
+as the server's operating time, i.e. the actual interval can be longer if
+*chronyd* is not running continuously. The default interval is 604800 seconds
+(1 week). The maximum value is 2^31-1 (68 years).
++
+The automatic rotation of the keys can be disabled by setting *ntsrotate* to 0.
+In this case the keys are assumed to be managed externally. *chronyd* will not
+save the keys to the _ntskeys_ file and will reload the keys from the file when
+the <<chronyc.adoc#rekey,*rekey*>> command is issued in *chronyc*. The file can
+be periodically copied from another server running *chronyd* (which does
+not have *ntsrotate* set to 0) in order to have one or more servers dedicated
+to NTS-KE. The file includes the subsequent key to which the NTS-KE server will
+switch on the next rotation, i.e. the process copying and reloading the file
+does not need to be timed precisely (it can be delayed by up to one rotation
+interval). The NTS-KE servers need to be configured with the
+<<ntsntpserver,*ntsntpserver*>> directive to point the clients to the right NTP
+server.
++
+An example of the directive is:
++
+----
+ntsrotate 2592000
+----
+
+[[port]]*port* _port_::
+This option allows you to configure the port on which *chronyd* will listen for
+NTP requests. The port will be open only when an address is allowed by the
+<<allow,*allow*>> directive or the <<chronyc.adoc#allow,*allow*>> command in
+*chronyc*, an NTP peer is configured, or the broadcast server mode is enabled.
++
+The default value is 123, the standard NTP port. If set to 0, *chronyd* will
+never open the server port and will operate strictly in a client-only mode. The
+source port used in NTP client requests can be set by the
+<<acquisitionport,*acquisitionport*>> directive.
+
+[[ratelimit]]*ratelimit* [_option_]...::
+This directive enables response rate limiting for NTP packets. Its purpose is
+to reduce network traffic with misconfigured or broken NTP clients that are
+polling the server too frequently. The limits are applied to individual IP
+addresses. If multiple clients share one IP address (e.g. multiple hosts behind
+NAT), the sum of their traffic will be limited. If a client that increases its
+polling rate when it does not receive a reply is detected, its rate limiting
+will be temporarily suspended to avoid increasing the overall amount of
+traffic. The maximum number of IP addresses which can be monitored at the same
+time depends on the memory limit set by the <<clientloglimit,*clientloglimit*>>
+directive.
++
+The *ratelimit* directive supports a number of options (which can be defined
+in any order):
++
+*interval* _interval_:::
+This option sets the minimum interval between responses. It is defined as a
+power of 2 in seconds. The default value is 3 (8 seconds). The minimum value
+is -19 (524288 packets per second) and the maximum value is 12 (one packet per
+4096 seconds). Note that with values below -4 the rate limiting is coarse
+(responses are allowed in bursts, even if the interval between them is shorter
+than the specified interval).
+*burst* _responses_:::
+This option sets the maximum number of responses that can be sent in a burst,
+temporarily exceeding the limit specified by the *interval* option. This is
+useful for clients that make rapid measurements on start (e.g. *chronyd* with
+the *iburst* option). The default value is 8. The minimum value is 1 and the
+maximum value is 255.
+*leak* _rate_:::
+This option sets the rate at which responses are randomly allowed even if the
+limits specified by the *interval* and *burst* options are exceeded. This is
+necessary to prevent an attacker who is sending requests with a spoofed
+source address from completely blocking responses to that address. The leak
+rate is defined as a power of 1/2 and it is 2 by default, i.e. on average at
+least every fourth request has a response. The minimum value is 1 and the
+maximum value is 4.
+{blank}::
++
+An example use of the directive is:
++
+----
+ratelimit interval 1 burst 16
+----
++
+This would reduce the response rate for IP addresses sending packets on average
+more than once per 2 seconds, or sending packets in bursts of more than 16
+packets, by up to 75% (with default *leak* of 2).
+
+[[ntsratelimit]]*ntsratelimit* [_option_]...::
+This directive enables rate limiting of NTS-KE requests. It is similar to the
+<<ratelimit,*ratelimit*>> directive, except the default interval is 6
+(1 connection per 64 seconds).
++
+An example of the use of the directive is:
++
+----
+ntsratelimit interval 3 burst 1
+----
+
+[[smoothtime]]*smoothtime* _max-freq_ _max-wander_ [*leaponly*]::
+The *smoothtime* directive can be used to enable smoothing of the time that
+*chronyd* serves to its clients to make it easier for them to track it and keep
+their clocks close together even when large offset or frequency corrections are
+applied to the server's clock, for example after being offline for a longer
+time.
++
+BE WARNED: The server is intentionally not serving its best estimate of the
+true time. If a large offset has been accumulated, it can take a very long time
+to smooth it out. This directive should be used only when the clients are not
+configured to also poll another NTP server, because they could reject this
+server as a falseticker or fail to select a source completely.
++
+The smoothing process is implemented with a quadratic spline function with two
+or three pieces. It is independent from any slewing applied to the local system
+clock, but the accumulated offset and frequency will be reset when the clock is
+corrected by stepping, e.g. by the <<makestep,*makestep*>> directive or the
+<<chronyc.adoc#makestep,*makestep*>> command in *chronyc*. The process can be
+reset without stepping the clock by the <<chronyc.adoc#smoothtime,*smoothtime
+reset*>> command.
++
+The first two arguments of the directive are the maximum frequency offset of
+the smoothed time to the tracked NTP time (in ppm) and the maximum rate at
+which the frequency offset is allowed to change (in ppm per second). *leaponly*
+is an optional third argument which enables a mode where only leap seconds are
+smoothed out and normal offset and frequency changes are ignored. The *leaponly*
+option is useful in a combination with the <<leapsecmode,*leapsecmode slew*>>
+directive to allow the clients to use multiple time smoothing servers safely.
++
+The smoothing process is activated automatically when 1/10000 of the estimated
+skew of the local clock falls below the maximum rate of frequency change. It
+can be also activated manually by the <<chronyc.adoc#smoothtime,*smoothtime
+activate*>> command, which is particularly useful when the clock is
+synchronised only with manual input and the skew is always larger than the
+threshold. The <<chronyc.adoc#smoothing,*smoothing*>> command can be used to
+monitor the process.
++
+An example suitable for clients using *ntpd* and 1024 second polling interval
+could be:
++
+----
+smoothtime 400 0.001
+----
++
+An example suitable for clients using *chronyd* on Linux could be:
++
+----
+smoothtime 50000 0.01
+----
+
+=== Command and monitoring access
+
+[[bindcmdaddress]]*bindcmdaddress* _address_::
+The *bindcmdaddress* directive specifies a local IP address to which *chronyd*
+will bind the UDP socket listening for monitoring command packets (issued
+by *chronyc*). On systems other than Linux, the address of the interface needs
+to be already configured when *chronyd* is started.
++
+This directive can also change the path of the Unix domain command socket,
+which is used by *chronyc* to send configuration commands. The socket must be
+in a directory that is accessible only by the root or _chrony_ user. The
+directory will be created on start if it does not exist. The compiled-in default
+path of the socket is _@CHRONYRUNDIR@/chronyd.sock_. The socket can be
+disabled by setting the path to _/_.
++
+By default, *chronyd* binds the UDP sockets to the addresses _127.0.0.1_ and
+_::1_ (i.e. the loopback interface). This blocks all access except from
+localhost. To listen for command packets on all interfaces, you can add the
+lines:
++
+----
+bindcmdaddress 0.0.0.0
+bindcmdaddress ::
+----
++
+to the configuration file.
++
+For each of the IPv4, IPv6, and Unix domain protocols, only one
+*bindcmdaddress* directive can be specified.
++
+An example that sets the path of the Unix domain command socket is:
++
+----
+bindcmdaddress /var/run/chrony/chronyd.sock
+----
+
+[[bindcmddevice]]*bindcmddevice* _interface_::
+The *bindcmddevice* directive binds the UDP command sockets to a network device
+specified by the interface name. This directive can specify only one interface
+and it is supported on Linux only.
++
+An example of the directive is:
++
+----
+bindcmddevice eth0
+----
+
+[[cmdallow]]*cmdallow* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> directive, except that it allows
+monitoring access (rather than NTP client access) to a particular subnet or
+host. (By '`monitoring access`' is meant that *chronyc* can be run on those
+hosts and retrieve monitoring data from *chronyd* on this computer.)
++
+The syntax is identical to the *allow* directive.
++
+There is also a *cmdallow all* directive with similar behaviour to the *allow
+all* directive (but applying to monitoring access in this case, of course).
++
+Note that *chronyd* has to be configured with the
+<<bindcmdaddress,*bindcmdaddress*>> directive to not listen only on the
+loopback interface to actually allow remote access.
+
+[[cmddeny]]*cmddeny* [*all*] [_subnet_]::
+This is similar to the <<cmdallow,*cmdallow*>> directive, except that it denies
+monitoring access to a particular subnet or host, rather than allowing it.
++
+The syntax is identical.
++
+There is also a *cmddeny all* directive with similar behaviour to the *cmdallow
+all* directive.
+
+[[cmdport]]*cmdport* _port_::
+The *cmdport* directive allows the port that is used for run-time monitoring
+(via the *chronyc* program) to be altered from its default (323). If set to 0,
+*chronyd* will not open the port, this is useful to disable *chronyc*
+access from the Internet. (It does not disable the Unix domain command socket.)
++
+An example shows the syntax:
++
+----
+cmdport 257
+----
++
+This would make *chronyd* use UDP 257 as its command port. (*chronyc* would
+need to be run with the *-p 257* switch to inter-operate correctly.)
+
+[[cmdratelimit]]*cmdratelimit* [_option_]...::
+This directive enables response rate limiting for command packets. It is
+similar to the <<ratelimit,*ratelimit*>> directive, except responses to
+localhost are never limited and the default interval is -4 (16 packets per
+second).
++
+An example of the use of the directive is:
++
+----
+cmdratelimit interval 2
+----
+
+=== Real-time clock (RTC)
+
+[[hwclockfile]]*hwclockfile* _file_::
+The *hwclockfile* directive sets the location of the adjtime file which is
+used by the *hwclock* program on Linux. *chronyd* parses the file to find out
+if the RTC keeps local time or UTC. It overrides the <<rtconutc,*rtconutc*>>
+directive.
++
+The compiled-in default value is '_@DEFAULT_HWCLOCK_FILE@_'.
++
+An example of the directive is:
++
+----
+hwclockfile /etc/adjtime
+----
+
+[[rtcautotrim]]*rtcautotrim* _threshold_::
+The *rtcautotrim* directive is used to keep the RTC close to the system clock
+automatically. When the system clock is synchronised and the estimated error
+between the two clocks is larger than the specified threshold, *chronyd* will
+trim the RTC as if the <<chronyc.adoc#trimrtc,*trimrtc*>> command in *chronyc*
+was issued. The trimming operation is accurate to only about 1 second, which is
+the minimum effective threshold.
++
+This directive is effective only with the <<rtcfile,*rtcfile*>> directive.
++
+An example of the use of this directive is:
++
+----
+rtcautotrim 30
+----
++
+This would set the threshold error to 30 seconds.
+
+[[rtcdevice]]*rtcdevice* _device_::
+The *rtcdevice* directive sets the path to the device file for accessing the
+RTC. The default path is _@DEFAULT_RTC_DEVICE@_.
+
+[[rtcfile]]*rtcfile* _file_::
+The *rtcfile* directive defines the name of the file in which *chronyd* can
+save parameters associated with tracking the accuracy of the RTC.
++
+An example of the directive is:
++
+----
+rtcfile @CHRONYVARDIR@/rtc
+----
++
+*chronyd* saves information in this file when it exits and when the *writertc*
+command is issued in *chronyc*. The information saved is the RTC's error at
+some epoch, that epoch (in seconds since January 1 1970), and the rate at which
+the RTC gains or loses time.
++
+So far, the support for real-time clocks is limited; their code is even more
+system-specific than the rest of the software. You can only use the RTC
+facilities (the <<rtcfile,*rtcfile*>> directive and the *-s* command-line
+option to *chronyd*) if the following three conditions apply:
++
+. You are running Linux.
+. The kernel is compiled with extended real-time clock support (i.e. the
+  _/dev/rtc_ device is capable of doing useful things).
+. You do not have other applications that need to make use of _/dev/rtc_ at all.
+
+[[rtconutc]]*rtconutc*::
+*chronyd* assumes by default that the RTC keeps local time (including any
+daylight saving changes). This is convenient on PCs running Linux which are
+dual-booted with Windows.
++
+If you keep the RTC on local time and your computer is off when daylight saving
+(summer time) starts or ends, the computer's system time will be one hour in
+error when you next boot and start chronyd.
++
+An alternative is for the RTC to keep Universal Coordinated Time (UTC). This
+does not suffer from the 1 hour problem when daylight saving starts or ends.
++
+If the *rtconutc* directive appears, it means the RTC is required to keep UTC.
+The directive takes no arguments. It is equivalent to specifying the *-u*
+switch to the Linux *hwclock* program.
++
+Note that this setting is overridden by the <<hwclockfile,*hwclockfile*>> file
+and is not relevant for the <<rtcsync,*rtcsync*>> directive.
+
+[[rtcsync]]*rtcsync*::
+The *rtcsync* directive enables a mode where the system time is periodically
+copied to the RTC and *chronyd* does not try to track its drift. This directive
+cannot be used with the <<rtcfile,*rtcfile*>> directive.
++
+On Linux, the RTC copy is performed by the kernel every 11 minutes.
++
+On macOS, <<chronyd,*chronyd*>> will perform the RTC copy every 60 minutes
+when the system clock is in a synchronised state.
++
+On other systems this directive does nothing.
+
+=== Logging
+
+[[log]]*log* [_option_]...::
+The *log* directive indicates that certain information is to be logged.
+The log files are written to the directory specified by the <<logdir,*logdir*>>
+directive. A banner is periodically written to the files to indicate the
+meanings of the columns.
++
+*rawmeasurements*:::
+This option logs the raw NTP measurements and related information to a file
+called _measurements.log_. An entry is made for each packet received from the
+source. This can be useful when debugging a problem. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
++
+----
+2016-11-09 05:40:50 203.0.113.15    N  2 111 111 1111  10 10 1.0 \
+   -4.966e-03  2.296e-01  1.577e-05  1.615e-01  7.446e-03 CB00717B 4B D K
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-10-13]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [05:40:50]
+. IP address of server or peer from which measurement came [203.0.113.15]
+. Leap status (_N_ means normal, _+_ means that the last minute of the current
+  month has 61 seconds, _-_ means that the last minute of the month has 59
+  seconds, _?_ means the remote computer is not currently synchronised.) [N]
+. Stratum of remote computer. [2]
+. RFC 5905 tests 1 through 3 (1=pass, 0=fail) [111]
+. RFC 5905 tests 5 through 7 (1=pass, 0=fail) [111]
+. Results of the *maxdelay*, *maxdelayratio*, and *maxdelaydevratio* (or
+  *maxdelayquant*) tests, and a test for synchronisation loop (1=pass,
+  0=fail). The first test from these four also checks the server precision,
+  response time, and whether an interleaved response is acceptable for
+  synchronisation. [1111]
+. Local poll [10]
+. Remote poll [10]
+. '`Score`' (an internal score within each polling level used to decide when to
+  increase or decrease the polling level. This is adjusted based on number of
+  measurements currently being used for the regression algorithm). [1.0]
+. The estimated local clock error (_theta_ in RFC 5905). Positive indicates
+  that the local clock is slow of the remote source. [-4.966e-03]
+. The peer delay (_delta_ in RFC 5905). [2.296e-01]
+. The peer dispersion (_epsilon_ in RFC 5905). [1.577e-05]
+. The root delay (_DELTA_ in RFC 5905). [1.615e-01]
+. The root dispersion (_EPSILON_ in RFC 5905). [7.446e-03]
+. Reference ID of the server's source as a hexadecimal number. [CB00717B]
+. NTP mode of the received packet (_1_=active peer, _2_=passive peer,
+  _4_=server, _B_=basic, _I_=interleaved). [4B]
+. Source of the local transmit timestamp
+  (_D_=daemon, _K_=kernel, _H_=hardware). [D]
+. Source of the local receive timestamp
+  (_D_=daemon, _K_=kernel, _H_=hardware). [K]
++
+*measurements*:::
+This option is identical to the *rawmeasurements* option, except it logs only
+valid measurements from synchronised sources, i.e. measurements which passed
+the RFC 5905 tests 1 through 7. This can be useful for producing graphs of the
+source's performance.
++
+*statistics*:::
+This option logs information about the regression processing to a file called
+_statistics.log_. An example line (which actually appears as a single line in
+the file) from the log file is shown below.
++
+----
+2016-08-10 05:40:50 203.0.113.15     6.261e-03 -3.247e-03 \
+     2.220e-03  1.874e-06  1.080e-06 7.8e-02  16   0   8  0.00
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-07-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [05:40:50]
+. IP address of server or peer from which measurement comes [203.0.113.15]
+. The estimated standard deviation of the measurements from the source (in
+  seconds). [6.261e-03]
+. The estimated offset of the source (in seconds, positive means the local
+  clock is estimated to be fast, in this case). [-3.247e-03]
+. The estimated standard deviation of the offset estimate (in seconds).
+  [2.220e-03]
+. The estimated rate at which the local clock is gaining or losing time
+  relative to the source (in seconds per second, positive means the local clock
+  is gaining). This is relative to the compensation currently being applied to
+  the local clock, _not_ to the local clock without any compensation.
+  [1.874e-06]
+. The estimated error in the rate value (in seconds per second). [1.080e-06].
+. The ratio of |old_rate - new_rate| / old_rate_error. Large values
+  indicate the statistics are not modelling the source very well. [7.8e-02]
+. The number of measurements currently being used for the regression
+  algorithm. [16]
+. The new starting index (the oldest sample has index 0; this is the method
+  used to prune old samples when it no longer looks like the measurements fit a
+  linear model). [0, i.e. no samples discarded this time]
+. The number of runs. The number of runs of regression residuals with the same
+  sign is computed. If this is too small it indicates that the measurements are
+  no longer represented well by a linear model and that some older samples need
+  to be discarded. The number of runs for the data that is being retained is
+  tabulated. Values of approximately half the number of samples are expected.
+  [8]
+. The estimated or configured asymmetry of network jitter on the path to the
+  source which was used to correct the measured offsets. The asymmetry can be
+  between -0.5 and +0.5. A negative value means the delay of packets sent to
+  the source is more variable than the delay of packets sent from the source
+  back. [0.00, i.e. no correction for asymmetry]
++
+*selection*:::
+This option logs information about selection of sources for synchronisation to
+a file called _selection.log_. Note that the rate of entries written to this
+file grows quadratically with the number of specified sources (each measurement
+triggers the selection for all sources). An example line (which actually
+appears as a single line in the file) from the log file is shown below.
++
+----
+2022-05-01 02:01:20 203.0.113.15    * -----  377  1.00  \
+     4.228e+01 -1.575e-04  1.239e-04
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2022-05-01]
+. Hour:Minute:Second. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [02:01:20]
+. IP address or reference ID of the source. [203.0.113.15]
+. State of the source indicated with one of the following symbols. [*]
+{blank}::::
+Not considered selectable for synchronisation:
+* _N_ - has the *noselect* option.
+* _s_ - is not synchronised.
+* _M_ - does not have enough measurements.
+* _d_ - has a root distance larger than the maximum distance (configured by the
+        <<maxdistance,*maxdistance*>> directive).
+* _~_ - has a jitter larger than the maximum jitter (configured by the
+        <<maxjitter,*maxjitter*>> directive).
+* _w_ - waits for other sources to get out of the _M_ state.
+* _S_ - has older measurements than other sources.
+* _O_ - has a stratum equal or larger than the orphan stratum (configured by
+        the <<local,*local*>> directive).
+* _T_ - does not fully agree with sources that have the *trust* option.
+* _x_ - does not agree with other sources (falseticker).
+{blank}::::
+Considered selectable for synchronisation, but not currently used:
+* _W_ - waits for other sources to be selectable (required by the
+        <<minsources,*minsources*>> directive, or the *require* option of
+        another source).
+* _P_ - another selectable source is preferred due to the *prefer* option.
+* _U_ - waits for a new measurement (after selecting a different best source).
+* _D_ - has, or recently had, a root distance which is too large to be combined
+        with other sources (configured by the <<combinelimit,*combinelimit*>>
+        directive).
+{blank}::::
+Used for synchronisation of the local clock:
+* _+_ - combined with the best source.
+* _*_ - selected as the best source to update the reference data (e.g. root
+        delay, root dispersion).
+. Current effective selection options of the source. which can be different
+  from the configured options due to the authentication selection mode
+  (configured by the <<authselectmode,*authselectmode*>> directive). [-----]
+* _N_ indicates the *noselect* option.
+* _P_ indicates the *prefer* option.
+* _T_ indicates the *trust* option.
+* _R_ indicates the *require* option.
+. Reachability register printed as an octal number. The register has 8 bits and
+  is updated on every received or missed packet from the source. A value of 377
+  indicates that a valid reply was received for all from the last eight
+  transmissions. [377]
+. Current score against the source in the _*_ state. The scoring system avoids
+  frequent reselection when multiple sources have a similar root distance. A
+  value larger than 1 indicates this source was better than the _*_ source in
+  recent selections. If the score reaches 10, the best source will be reselected
+  and the scores will be reset to 1. [1.00]
+. Interval since the last measurement of the source in seconds. [4.228e+01]
+. Lower endpoint of the interval which was expected to contain the true offset
+  of the local clock determined by the root distance of the source. [-1.575e-04]
+. Upper endpoint of the interval which was expected to contain the true offset
+  of the local clock determined by the root distance of the source. [1.239e-04]
++
+*tracking*:::
+This option logs changes to the estimate of the system's gain or loss rate, and
+any slews made, to a file called _tracking.log_. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
++
+----
+2017-08-22 13:22:36 203.0.113.15     2     -3.541      0.075 -8.621e-06 N \
+            2  2.940e-03 -2.084e-04  1.534e-02  3.472e-04  8.304e-03
+----
++
+The columns are as follows (the quantities in square brackets are the
+values from the example line above) :
++
+. Date [2017-08-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [13:22:36]
+. The IP address of the server or peer to which the local system is synchronised.
+  [203.0.113.15]
+. The stratum of the local system. [2]
+. The local system frequency (in ppm, positive means the local system runs fast
+  of UTC). [-3.541]
+. The error bounds on the frequency (in ppm). [0.075]
+. The estimated local offset at the epoch, which is normally corrected by
+  slewing the local clock (in seconds, positive indicates the clock is fast of
+  UTC). [-8.621e-06]
+. Leap status (_N_ means normal, _+_ means that the last minute of this month
+  has 61 seconds, _-_ means that the last minute of the month has 59 seconds,
+  _?_ means the clock is not currently synchronised.) [N]
+. The number of combined sources. [2]
+. The estimated standard deviation of the combined offset (in seconds).
+  [2.940e-03]
+. The remaining offset correction from the previous update (in seconds,
+  positive means the system clock is slow of UTC). [-2.084e-04]
+. The total of the network path delays to the reference clock to which
+  the local clock is ultimately synchronised (in seconds). [1.534e-02]
+. The total dispersion accumulated through all the servers back to the
+  reference clock to which the local clock is ultimately synchronised
+  (in seconds). [3.472e-04]
+. The maximum estimated error of the system clock in the interval since the
+  previous update (in seconds). It includes the offset, remaining offset
+  correction, root delay, and dispersion from the previous update with the
+  dispersion which accumulated in the interval. [8.304e-03]
++
+*rtc*:::
+This option logs information about the system's real-time clock. An example
+line (which actually appears as a single line in the file) from the _rtc.log_
+file is shown below.
++
+----
+2015-07-22 05:40:50     -0.037360 1       -0.037434\
+          -37.948  12   5  120
+----
++
+The columns are as follows (the quantities in square brackets are the
+values from the example line above):
++
+. Date [2015-07-22]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [05:40:50]
+. The measured offset between the RTC and the system clock in seconds.
+  Positive indicates that the RTC is fast of the system time [-0.037360].
+. Flag indicating whether the regression has produced valid coefficients.
+  (1 for yes, 0 for no). [1]
+. Offset at the current time predicted by the regression process. A large
+  difference between this value and the measured offset tends to indicate that
+  the measurement is an outlier with a serious measurement error. [-0.037434]
+. The rate at which the RTC is losing or gaining time relative to the system
+  clock. In ppm, with positive indicating that the RTC is gaining time.
+  [-37.948]
+. The number of measurements used in the regression. [12]
+. The number of runs of regression residuals of the same sign. Low values
+  indicate that a straight line is no longer a good model of the measured data
+  and that older measurements should be discarded. [5]
+. The measurement interval used prior to the measurement being made (in
+  seconds). [120]
++
+*refclocks*:::
+This option logs the raw and filtered reference clock measurements to a file
+called _refclocks.log_. An example line (which actually appears as a single
+line in the file) from the log file is shown below.
++
+----
+2009-11-30 14:33:27.000000 PPS2    7 N 1  4.900000e-07 -6.741777e-07  1.000e-06
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2009-11-30]
+. Hour:Minute:Second.Microsecond. Note that the date-time pair is expressed in
+  UTC, not the local time zone. [14:33:27.000000]
+. Reference ID of the reference clock from which the measurement came. [PPS2]
+. Sequence number of driver poll within one polling interval for raw samples,
+  or _-_ for filtered samples. [7]
+. Leap status (_N_ means normal, _+_ means that the last minute of the current
+  month has 61 seconds, _-_ means that the last minute of the month has 59
+  seconds). [N]
+. Flag indicating whether the sample comes from PPS source. (1 for yes,
+  0 for no, or _-_ for filtered sample). [1]
+. Local clock error measured by reference clock driver, or _-_ for filtered sample.
+  [4.900000e-07]
+. Local clock error with applied corrections. Positive indicates that the local
+  clock is slow. [-6.741777e-07]
+. Assumed dispersion of the sample. [1.000e-06]
++
+*tempcomp*:::
+This option logs the temperature measurements and system rate compensations to
+a file called _tempcomp.log_. An example line (which actually appears as a
+single line in the file) from the log file is shown below.
++
+----
+2015-04-19 10:39:48  2.8000e+04  3.6600e-01
+----
++
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
++
+. Date [2015-04-19]
+. Hour:Minute:Second. Note that the date-time pair is expressed in UTC, not the
+  local time zone. [10:39:48]
+. Temperature read from the sensor. [2.8000e+04]
+. Applied compensation in ppm, positive means the system clock is running
+  faster than it would be without the compensation. [3.6600e-01]
++
+{blank}::
+An example of the directive is:
++
+----
+log measurements statistics tracking
+----
+
+[[logbanner]]*logbanner* _entries_::
+A banner is periodically written to the log files enabled by the <<log,*log*>>
+directive to indicate the meanings of the columns.
++
+The *logbanner* directive specifies after how many entries in the log file
+should be the banner written. The default is 32, and 0 can be used to disable
+it entirely.
+
+[[logchange]]*logchange* _threshold_::
+This directive sets the threshold for the adjustment of the system clock that
+will generate a syslog message. Clock errors detected via NTP packets,
+reference clocks, or timestamps entered via the
+<<chronyc.adoc#settime,*settime*>> command of *chronyc* are logged.
++
+By default, the threshold is 1 second.
++
+An example of the use is:
++
+----
+logchange 0.1
+----
++
+which would cause a syslog message to be generated if a system clock error of over
+0.1 seconds starts to be compensated.
+
+[[logdir]]*logdir* _directory_::
+This directive specifies the directory for writing log files enabled by the
+*log* directive. If the directory does not exist, it will be created
+automatically.
++
+An example of the use of this directive is:
++
+----
+logdir /var/log/chrony
+----
+
+[[mailonchange]]*mailonchange* _email_ _threshold_::
+This directive defines an email address to which mail should be sent if
+*chronyd* applies a correction exceeding a particular threshold to the system
+clock.
++
+An example of the use of this directive is:
++
+----
+mailonchange root@localhost 0.5
+----
++
+This would send a mail message to root if a change of more than 0.5 seconds
+were applied to the system clock.
++
+This directive cannot be used when a system call filter is enabled by the *-F*
+option as the *chronyd* process will not be allowed to fork and execute the
+sendmail binary.
+
+=== Miscellaneous
+
+[[confdir]]*confdir* _directory_...::
+The *confdir* directive includes configuration files with the _.conf_ suffix
+from a directory. The files are included in the lexicographical order of the
+file names.
++
+Multiple directories (up to 10) can be specified with a single *confdir*
+directive. In this case, if multiple directories contain a file with the same
+name, only the first file in the order of the specified directories will be
+included. This enables a fragmented configuration where existing fragments can
+be replaced by adding files to a different directory.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+confdir @SYSCONFDIR@/chrony.d
+----
+
+[[sourcedir]]*sourcedir* _directory_...::
+The *sourcedir* directive is identical to the *confdir* directive, except the
+configuration files have the _.sources_ suffix, they can only specify NTP
+sources (i.e. the *server*, *pool*, and *peer* directives), they are expected
+to have all lines terminated by the newline character, and they can be
+reloaded by the <<chronyc.adoc#reload,*reload sources*>> command in
+*chronyc*. It is particularly useful with dynamic sources like NTP servers
+received from a DHCP server, which can be written to a file specific to the
+network interface by a networking script.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+sourcedir /var/run/chrony-dhcp
+----
+
+[[include]]*include* _pattern_::
+The *include* directive includes a configuration file, or multiple configuration
+files if a wildcard pattern is specified. Unlike with the *confdir* directive,
+the full name of the files needs to be specified and at least one file is
+required to exist.
++
+This directive can be used multiple times.
++
+An example of the directive is:
++
+----
+include @SYSCONFDIR@/chrony.d/*.conf
+----
+
+[[hwtimestamp]]*hwtimestamp* _interface_ [_option_]...::
+This directive enables hardware timestamping of NTP packets sent to and
+received from the specified network interface. The network interface controller
+(NIC) uses its own clock to accurately timestamp the actual transmissions and
+receptions, avoiding processing and queueing delays in the kernel, network
+driver, and hardware. This can significantly improve the accuracy of the
+timestamps and the measured offset, which is used for synchronisation of the
+system clock. In order to get the best results, both sides receiving and
+sending NTP packets (i.e. server and client, or two peers) need to use HW
+timestamping. If the server or peer supports the interleaved mode, it needs to
+be enabled by the *xleave* option in the <<server,*server*>> or the
+<<peer,*peer*>> directive.
++
+This directive is supported on Linux 3.19 and newer. The NIC must support HW
+timestamping, which can be verified with the *ethtool -T* command. The list of
+capabilities should include _hardware-raw-clock_, _hardware-transmit_, and
+_hardware-receive_. The receive filter _all_, or _ntp_, is necessary for
+timestamping of received NTP packets. Timestamping of packets received on
+bridged and bonded interfaces is supported on Linux 4.13 and newer. If HW
+timestamping does not work for received packets, *chronyd* will use kernel
+receive timestamps instead. Transmit-only HW timestamping can still be useful
+to improve stability of the synchronisation.
++
+*chronyd* does not synchronise the NIC clock. It assumes the clock is running
+free. Multiple instances of *chronyd* can use the same interface with enabled
+HW timestamping. Applications which need HW timestamping with a synchronised
+clock (e.g. a PTP daemon) should use a virtual clock running on top of the
+physical clock created by writing to _/sys/class/ptp/ptpX/n_vclocks_. This
+feature is available on Linux 5.14 and newer.
++
+If the kernel supports software timestamping, it will be enabled for all
+interfaces automatically.
++
+The source of timestamps (i.e. hardware, kernel, or daemon) is indicated on the
+client side in the _measurements.log_ file (if enabled by the <<log,*log*>>
+directive) and the <<chronyc.adoc#ntpdata,*ntpdata*>> report. On the server
+side, the number of served timestamps from each source is provided in the
+<<chronyc.adoc#serverstats,*serverstats*>> report.
++
+This directive can be used multiple times to enable HW timestamping on multiple
+interfaces. If the specified interface is _*_, *chronyd* will try to enable HW
+timestamping on all available interfaces.
++
+The *hwtimestamp* directive has the following options:
++
+*minpoll* _poll_:::
+This option specifies the minimum interval between readings of the NIC clock.
+It's defined as a power of 2. It should correspond to the minimum polling
+interval of all NTP sources and the minimum expected polling interval of NTP
+clients. The default value is 0 (1 second), the minimum value is -6 (1/64th
+of a second), and the maximum value is 20 (about 12 days).
+*maxpoll* _poll_:::
+This option specifies the maximum interval between readings of the NIC clock,
+as a power of 2. The default value is *minpoll* + 1, i.e. 1 (2 seconds) with
+the default *minpoll* of 0. The minimum and maximum values are the same as with
+the *minpoll* option.
+*minsamples* _samples_:::
+This option specifies the minimum number of readings kept for tracking of the
+NIC clock. The default value is 2.
+*maxsamples* _samples_:::
+This option specifies the maximum number of readings kept for tracking of the
+NIC clock. The default value is 16.
+*precision* _precision_:::
+This option specifies the assumed precision of reading of the NIC clock. The
+default value is 100e-9 (100 nanoseconds).
+*txcomp* _compensation_:::
+This option specifies the difference in seconds between the actual transmission
+time at the physical layer and the reported transmit timestamp. This value will
+be added to transmit timestamps obtained from the NIC. The default value is 0.
+*rxcomp* _compensation_:::
+This option specifies the difference in seconds between the reported receive
+timestamp and the actual reception time at the physical layer. This value will
+be subtracted from receive timestamps obtained from the NIC. The default value
+is 0.
+*nocrossts*:::
+Some hardware can precisely cross timestamp the NIC clock with the system
+clock. This option disables the use of the cross timestamping.
+*rxfilter* _filter_:::
+This option selects the receive timestamping filter. The _filter_ can be one of
+the following:
+_all_::::
+Enables timestamping of all received packets.
+_ntp_::::
+Enables timestamping of received NTP packets.
+_ptp_::::
+Enables timestamping of received PTP packets.
+_none_::::
+Disables timestamping of received packets.
+{blank}:::
+The most specific filter for timestamping of NTP packets supported by the NIC
+is selected by default. Some NICs can timestamp PTP packets only. By default,
+they will be configured with the _none_ filter and expected to provide hardware
+timestamps for transmitted packets only. Timestamping of PTP packets is useful
+with NTP-over-PTP enabled by the <<chrony.conf.adoc#ptpport,*ptpport*>>
+directive, or when another application is receiving PTP packets on the
+interface. Forcing timestamping of all packets with the _all_ filter could be
+useful if the NIC supported both the _all_ and _ntp_ filters, and it should
+timestamp both NTP and PTP packets, or NTP packets on a different UDP port.
+{blank}::
++
+Examples of the directive are:
++
+----
+hwtimestamp eth0
+hwtimestamp eth1 txcomp 300e-9 rxcomp 645e-9
+hwtimestamp *
+----
+
+[[hwtstimeout]]*hwtstimeout* _timeout_::
+If hardware timestamping is used with a close NTP server, or the NIC or its
+driver is slow in providing the transmit timestamp of NTP requests, a response
+from the server can be received before the transmit timestamp of the request.
+To avoid calculating the offset with a less accurate transmit timestamp,
+*chronyd* can save the response for later processing and wait for the hardware
+transmit timestamp. There is no guarantee that the timestamp will be provided
+(NICs typically have a limited rate of transmit timestamping). This directive
+configures how long should *chronyd* wait for the timestamp after receiving a
+valid response from the server. If a second valid response is received from the
+server while waiting for the timestamp, they will be both processed
+immediately.
++
+The default value is 0.001 seconds, which should be sufficient with most
+hardware. If you frequently see kernel transmit timestamps in the
+_measurements.log_ file or <<chronyc.adoc#ntpdata,*ntpdata*>> report, and it is
+not a server handling a high rate of requests in the interleaved mode on the
+same interface (which would compete with timestamping of the server's own
+requests), increasing the timeout to 0.01 or possibly even longer might help.
+Note that the maximum timeout is limited by the NTP polling interval.
+
+[[keyfile]]*keyfile* _file_::
+This directive is used to specify the location of the file containing symmetric
+keys which are shared between NTP servers and clients, or peers, in order to
+authenticate NTP packets with a message authentication code (MAC) using a
+cryptographic hash function or cipher.
++
+The format of the directive is shown in the example below:
++
+----
+keyfile @SYSCONFDIR@/chrony.keys
+----
++
+The argument is simply the name of the file containing the ID-key pairs. The
+format of the file is shown below:
++
+----
+10 tulip
+11 hyacinth
+20 MD5 ASCII:crocus
+25 SHA1 HEX:933F62BE1D604E68A81B557F18CFA200483F5B70
+30 AES128 HEX:7EA62AE64D190114D46D5A082F948EC1
+31 AES256 HEX:37DDCBC67BB902BCB8E995977FAB4D2B5642F5B32EBCEEE421921D97E5CBFE39
+ ...
+----
++
+Each line consists of an ID, optional type, and key.
++
+The ID can be any positive integer in the range 1 through 2^32-1.
++
+The type is a name of a cryptographic hash function or cipher which is used to
+generate and verify the MAC. The default type is *MD5*, which is always
+supported.
+If *chronyd* was built with enabled support for hashing using a crypto library
+(Nettle, GnuTLS, NSS, or LibTomCrypt), the following functions are available: *MD5*,
+*SHA1*, *SHA256*, *SHA384*, *SHA512*. Depending on which library and version is
+*chronyd* using, some of the following hash functions and ciphers may
+also be available:
+*SHA3-224*, *SHA3-256*, *SHA3-384*, *SHA3-512*, *TIGER*, *WHIRLPOOL*, *AES128*,
+*AES256*.
++
+The key can be specified as a string of ASCII characters not containing white
+space with an optional *ASCII:* prefix, or as a hexadecimal number with the
+*HEX:* prefix. The maximum length of the line is 2047 characters.
+If the type is a cipher, the length of the key must match the cipher (i.e. 128
+bits for AES128 and 256 bits for AES256).
++
+It is recommended to use randomly generated keys, specified in the hexadecimal
+format, which are at least 128 bits long (i.e. they have at least 32 characters
+after the *HEX:* prefix). *chronyd* will log a warning to syslog on start if a
+source is specified in the configuration file with a key shorter than 80 bits.
++
+The recommended key types are AES ciphers and SHA3 hash functions. MD5 should
+be avoided unless no other type is supported on the server and client, or
+peers.
++
+The <<chronyc.adoc#keygen,*keygen*>> command of *chronyc* can be used to
+generate random keys for the key file. By default, it generates 160-bit MD5 or
+SHA1 keys.
++
+For security reasons, the file should be readable only by root and the user
+under which *chronyd* is normally running (to allow *chronyd* to re-read the
+file when the <<chronyc.adoc#rekey,*rekey*>> command is issued by *chronyc*).
+
+[[lock_all]]*lock_all*::
+The *lock_all* directive will lock the *chronyd* process into RAM so that it
+will never be paged out. This can result in lower and more consistent latency.
+The directive is supported on Linux, FreeBSD, NetBSD, and illumos.
+
+[[pidfile]]*pidfile* _file_::
+Unless *chronyd* is started with the *-Q* option, it writes its process ID
+(PID) to a file, and checks this file on startup to see if another *chronyd*
+might already be running on the system. By default, the file used is
+_@DEFAULT_PID_FILE@_. The *pidfile* directive allows the name to be changed,
+e.g.:
++
+----
+pidfile /run/chronyd.pid
+----
+
+[[ptpport]]*ptpport* _port_::
+The *ptpport* directive enables *chronyd* to send and receive NTP messages
+contained in PTP event messages (NTP-over-PTP) to enable hardware timestamping
+on NICs which cannot timestamp NTP packets, but can timestamp unicast PTP
+packets. The port recognized by the NICs is 319 (PTP event port). The default
+value is 0 (disabled).
++
+The NTP-over-PTP support is experimental. The protocol and configuration can
+change in future. It should be used only in local networks and expected to work
+only between servers and clients running the same version of *chronyd*.
++
+The PTP port will be open even if *chronyd* is not configured to operate as a
+server or client. The directive does not change the default protocol of
+specified NTP sources. Each NTP source that should use NTP-over-PTP needs to
+be specified with the *port* option set to the PTP port. To actually enable
+hardware timestamping on NICs which can timestamp PTP packets only, the
+*rxfilter* option of the *hwtimestamp* directive needs to be set to _ptp_.
++
+An example of client configuration is:
++
+----
+server foo.example.net minpoll 0 maxpoll 0 xleave port 319
+hwtimestamp * rxfilter ptp
+ptpport 319
+----
+
+[[sched_priority]]*sched_priority* _priority_::
+On Linux, FreeBSD, NetBSD, and illumos, the *sched_priority* directive will
+select the SCHED_FIFO real-time scheduler at the specified priority (which must
+be between 0 and 100). On macOS, this option must have either a value of 0 (the
+default) to disable the thread time constraint policy or 1 for the policy to be
+enabled.
++
+On systems other than macOS, this directive uses the *pthread_setschedparam()*
+system call to instruct the kernel to use the SCHED_FIFO first-in, first-out
+real-time scheduling policy for *chronyd* with the specified priority. This
+means that whenever *chronyd* is ready to run it will run, interrupting
+whatever else is running unless it is a higher priority real-time process. This
+should not impact performance as *chronyd* resource requirements are modest,
+but it should result in lower and more consistent latency since *chronyd* will
+not need to wait for the scheduler to get around to running it. You should not
+use this unless you really need it. The *pthread_setschedparam(3)* man page has
+more details.
++
+On macOS, this directive uses the *thread_policy_set()* kernel call to
+specify real-time scheduling. As noted above, you should not use this directive
+unless you really need it.
+
+[[user]]*user* _user_::
+The *user* directive sets the name of the system user to which *chronyd* will
+switch after start in order to drop root privileges.
++
+On Linux, *chronyd* needs to be compiled with support for the *libcap* library.
+On macOS, FreeBSD, NetBSD and illumos *chronyd* forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
++
+The compiled-in default value is _@DEFAULT_USER@_.
+
+[[examples]]
+== EXAMPLES
+
+=== NTP client with permanent connection to NTP servers
+
+This section shows how to configure *chronyd* for computers that are connected
+to the Internet (or to any network containing true NTP servers which ultimately
+derive their time from a reference clock) permanently or most of the time.
+
+To operate in this mode, you will need to know the names of the NTP servers
+you want to use. You might be able to find names of suitable servers by one of
+the following methods:
+
+* Your institution might already operate servers on its network.
+  Contact your system administrator to find out.
+* Your ISP probably has one or more NTP servers available for its
+  customers.
+* Somewhere under the NTP homepage there is a list of public
+  stratum 1 and stratum 2 servers. You should find one or more servers that are
+  near to you. Check that their access policy allows you to use their
+  facilities.
+* Use public servers from the https://www.pool.ntp.org/[pool.ntp.org] project.
+
+Assuming that your NTP servers are called _foo.example.net_, _bar.example.net_
+and _baz.example.net_, your _chrony.conf_ file could contain as a minimum:
+
+----
+server foo.example.net
+server bar.example.net
+server baz.example.net
+----
+
+However, you will probably want to include some of the other directives. The
+<<driftfile,*driftfile*>>, <<makestep,*makestep*>> and <<rtcsync,*rtcsync*>>
+might be particularly useful. Also, the *iburst* option of the
+<<server,*server*>> directive is useful to speed up the initial
+synchronisation. The smallest useful configuration file would look something
+like:
+
+----
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+When using a pool of NTP servers (one name is used for multiple servers which
+might change over time), it is better to specify them with the <<pool,*pool*>>
+directive instead of multiple *server* directives. The configuration file could
+in this case look like:
+
+----
+pool pool.ntp.org iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+If the servers (or pool) support the Network Time Security (NTS)
+authentication mechanism and *chronyd* is compiled with NTS support, the *nts*
+option will enable a secure synchronisation to the servers. The configuration
+file could look like:
+
+----
+server foo.example.net iburst nts
+server bar.example.net iburst nts
+server baz.example.net iburst nts
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+=== NTP client with infrequent connection to NTP servers
+
+This section shows how to configure *chronyd* for computers that have
+occasional connections to NTP servers. In this case, you will need some
+additional configuration to tell *chronyd* when the connection goes up and
+down. This saves the program from continuously trying to poll the servers when
+they are inaccessible.
+
+Again, assuming that your NTP servers are called _foo.example.net_,
+_bar.example.net_ and _baz.example.net_, your _chrony.conf_ file would now
+contain:
+
+----
+server foo.example.net offline
+server bar.example.net offline
+server baz.example.net offline
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+----
+
+The *offline* keyword indicates that the servers start in an offline state, and
+that they should not be contacted until *chronyd* receives notification from
+*chronyc* that the link to the Internet is present. To tell *chronyd* when to
+start and finish sampling the servers, the <<chronyc.adoc#online,*online*>> and
+<<chronyc.adoc#offline,*offline*>> commands of *chronyc* need to be used.
+
+To give an example of their use, assuming that *pppd* is the program being
+used to connect to the Internet and that *chronyc* has been installed at
+_@BINDIR@/chronyc_, the script _/etc/ppp/ip-up_ would include:
+
+----
+@BINDIR@/chronyc online
+----
+
+and the script _/etc/ppp/ip-down_ would include:
+
+----
+@BINDIR@/chronyc offline
+----
+
+*chronyd*'s polling of the servers would now only occur whilst the machine is
+actually connected to the Internet.
+
+=== Isolated networks
+
+This section shows how to configure *chronyd* for computers that never have
+network connectivity to any computer which ultimately derives its time from a
+reference clock.
+
+In this situation, one computer is selected to be the primary timeserver. The
+other computers are either direct clients of the server, or clients of clients.
+
+The <<local,*local*>> directive enables a local reference mode, which allows
+*chronyd* to appear synchronised even when it is not.
+
+The rate value in the server's drift file needs to be set to the average rate
+at which the server gains or loses time. *chronyd* includes support for this,
+in the form of the <<manual,*manual*>> directive and the
+<<chronyc.adoc#settime,*settime*>> command in the *chronyc* program.
+
+If the server is rebooted, *chronyd* can re-read the drift rate from the drift
+file. However, the server has no accurate estimate of the current time. To get
+around this, the system can be configured so that the server can initially set
+itself to a '`majority-vote`' of selected clients' times; this allows the
+clients to '`flywheel`' the server while it is rebooting.
+
+The <<smoothtime,*smoothtime*>> directive is useful when the clocks of the
+clients need to stay close together when the local time is adjusted by the
+<<chronyc.adoc#settime,*settime*>> command. The smoothing process needs to be
+activated by the <<chronyc.adoc#smoothtime,*smoothtime activate*>> command when
+the local time is ready to be served. After that point, any adjustments will be
+smoothed out.
+
+A typical configuration file for the server (called _ntp.local_) might be
+(assuming the clients and the server are in the _192.168.165.x_ subnet):
+
+----
+initstepslew 1 client1 client3 client6
+driftfile @CHRONYVARDIR@/drift
+local stratum 8
+manual
+allow 192.168.165.0/24
+smoothtime 400 0.01
+rtcsync
+----
+
+For the clients that have to resynchronise the server when it restarts,
+the configuration file might be:
+
+----
+server ntp.local iburst
+driftfile @CHRONYVARDIR@/drift
+allow 192.168.165.0/24
+makestep 1.0 3
+rtcsync
+----
+
+The rest of the clients would be the same, except that the *allow* directive is
+not required.
+
+If there is no suitable computer to be designated as the primary server, or
+there is a requirement to keep the clients synchronised even when it fails, the
+*orphan* option of the *local* directive enables a special mode where the
+server is selected from multiple computers automatically. They all need to use
+the same *local* configuration and poll one another. The server with the
+smallest reference ID (which is based on its IP address) will take the role of
+the primary server and others will be synchronised to it. When it fails, the
+server with the second smallest reference ID will take over and so on.
+
+A configuration file for the first server might be (assuming there are three
+servers called _ntp1.local_, _ntp2.local_, and _ntp3.local_):
+
+----
+initstepslew 1 ntp2.local ntp3.local
+server ntp2.local
+server ntp3.local
+driftfile @CHRONYVARDIR@/drift
+local stratum 8 orphan
+manual
+allow 192.168.165.0/24
+rtcsync
+----
+
+The other servers would be the same, except the hostnames in the *initstepslew*
+and *server* directives would be modified to specify the other servers. Their
+clients might be configured to poll all three servers.
+
+=== RTC tracking
+
+This section considers a computer which has occasional connections to the
+Internet and is turned off between '`sessions`'. In this case, *chronyd* relies
+on the computer's RTC to maintain the time between the periods when it is
+powered up. It assumes that Linux is run exclusively on the computer. Dual-boot
+systems might work; it depends what (if anything) the other system does to the
+RTC. On 2.6 and later kernels, if your motherboard has a HPET, you will need to
+enable the *HPET_EMULATE_RTC* option in your kernel configuration. Otherwise,
+*chronyd* will not be able to interact with the RTC device and will give up
+using it.
+
+When the computer is connected to the Internet, *chronyd* has access to
+external NTP servers which it makes measurements from. These measurements are
+saved, and straight-line fits are performed on them to provide an estimate of
+the computer's time error and rate of gaining or losing time.
+
+When the computer is taken offline from the Internet, the best estimate of the
+gain or loss rate is used to free-run the computer until it next goes online.
+
+Whilst the computer is running, *chronyd* makes measurements of the RTC (via
+the _/dev/rtc_ interface, which must be compiled into the kernel). An estimate
+is made of the RTC error at a particular RTC second, and the rate at which the
+RTC gains or loses time relative to true time.
+
+When the computer is powered down, the measurement histories for all the NTP
+servers are saved to files, and the RTC tracking information is also
+saved to a file (if the <<rtcfile,*rtcfile*>> directive has been specified).
+These pieces of information are also saved if the <<chronyc.adoc#dump,*dump*>>
+and <<chronyc.adoc#writertc,*writertc*>> commands respectively are issued
+through *chronyc*.
+
+When the computer is rebooted, *chronyd* reads the current RTC time and the RTC
+information saved at the last shutdown. This information is used to set the
+system clock to the best estimate of what its time would have been now, had it
+been left running continuously. The measurement histories for the servers are
+then reloaded.
+
+The next time the computer goes online, the previous sessions' measurements can
+contribute to the line-fitting process, which gives a much better estimate of
+the computer's gain or loss rate.
+
+One problem with saving the measurements and RTC data when the machine is shut
+down is what happens if there is a power failure; the most recent data will not
+be saved. Although *chronyd* is robust enough to cope with this, some
+performance might be lost. (The main danger arises if the RTC has been changed
+during the session, with the *trimrtc* command in *chronyc*. Because of this,
+*trimrtc* will make sure that a meaningful RTC file is saved after the
+change is completed).
+
+The easiest protection against power failure is to put the *dump* and
+*writertc* commands in the same place as the *offline* command is issued to
+take *chronyd* offline; because *chronyd* free-runs between online sessions, no
+parameters will change significantly between going offline from the Internet
+and any power failure.
+
+A final point regards computers which are left running for extended periods and
+where it is desired to spin down the hard disc when it is not in use (e.g. when
+not accessed for 15 minutes). *chronyd* has been planned so it supports such
+operation; this is the reason why the RTC tracking parameters are not saved to
+disc after every update, but only when the user requests such a write, or
+during the shutdown sequence. The only other facility that will generate
+periodic writes to the disc is the *log rtc* facility in the configuration
+file; this option should not be used if you want your disc to spin down.
+
+To illustrate how a computer might be configured for this case, example
+configuration files are shown.
+
+For the _chrony.conf_ file, the following can be used as an example.
+
+----
+server foo.example.net maxdelay 0.4 offline
+server bar.example.net maxdelay 0.4 offline
+server baz.example.net maxdelay 0.4 offline
+logdir /var/log/chrony
+log statistics measurements tracking
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+maxupdateskew 100.0
+dumpdir @CHRONYVARDIR@
+rtcfile @CHRONYVARDIR@/rtc
+----
+
+*pppd* is used for connecting to the Internet. This runs two scripts
+_/etc/ppp/ip-up_ and _/etc/ppp/ip-down_ when the link goes online and offline
+respectively.
+
+The relevant part of the _/etc/ppp/ip-up_ file is:
+
+----
+@BINDIR@/chronyc online
+----
+
+and the relevant part of the _/etc/ppp/ip-down_ script is:
+
+----
+@BINDIR@/chronyc -m offline dump writertc
+----
+
+*chronyd* is started during the boot sequence with the *-r* and *-s* options.
+It might need to be started before any software that depends on the system clock
+not jumping or moving backwards, depending on the directives in *chronyd*'s
+configuration file.
+
+For the system shutdown, *chronyd* should receive a SIGTERM several seconds
+before the final SIGKILL; the SIGTERM causes the measurement histories and RTC
+information to be saved.
+
+=== Public NTP server
+
+*chronyd* can be configured to operate as a public NTP server, e.g. to join the
+https://www.pool.ntp.org/en/join.html[pool.ntp.org] project. The configuration
+is similar to the NTP client with permanent connection, except it needs to
+allow client access from all addresses. It is recommended to find at least four
+good servers (e.g. from the pool, or on the NTP homepage). If the server has a
+hardware reference clock (e.g. a GPS receiver), it can be specified by the
+<<refclock,*refclock*>> directive.
+
+The amount of memory used for logging client accesses can be increased in order
+to enable clients to use the interleaved mode even when the server has a large
+number of clients, and better support rate limiting if it is enabled by the
+<<ratelimit,*ratelimit*>> directive. The system timezone database, if it is
+kept up to date and includes the _right/UTC_ timezone, can be used as a
+reliable source to determine when a leap second will be applied to UTC. The
+*-r* option with the <<dumpdir,*dumpdir*>> directive shortens the time in which
+*chronyd* will not be able to serve time to its clients when it needs to be
+restarted (e.g. after upgrading to a newer version, or a change in the
+configuration).
+
+The configuration file could look like:
+
+----
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+server qux.example.net iburst
+makestep 1.0 3
+rtcsync
+allow
+clientloglimit 100000000
+leapsectz right/UTC
+driftfile @CHRONYVARDIR@/drift
+dumpdir @CHRONYRUNDIR@
+----
+
+== SEE ALSO
+
+<<chronyc.adoc#,*chronyc(1)*>>, <<chronyd.adoc#,*chronyd(8)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony-project.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chrony.conf.man.in b/doc/chrony.conf.man.in
new file mode 100644
index 0000000..f3e52d9
--- /dev/null
+++ b/doc/chrony.conf.man.in
@@ -0,0 +1,5024 @@
+'\" t
+.\"     Title: chrony.conf
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.20
+.\"      Date: 2023-08-09
+.\"    Manual: Configuration Files
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONY.CONF" "5" "2023-08-09" "chrony @CHRONY_VERSION@" "Configuration Files"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chrony.conf \- chronyd configuration file
+.SH "SYNOPSIS"
+.sp
+\fBchrony.conf\fP
+.SH "DESCRIPTION"
+.sp
+This file configures the \fBchronyd\fP daemon. The compiled\-in location is
+\fI@SYSCONFDIR@/chrony.conf\fP. Other locations can be specified on the
+\fBchronyd\fP command line with the \fB\-f\fP option.
+.sp
+Each directive in the configuration file is placed on a separate line. The
+following sections describe each of the directives in turn. The directives are
+not case\-sensitive. Generally, the directives can occur in any order in the file
+and if a directive is specified multiple times, only the last one will be
+effective. Exceptions are noted in the descriptions.
+.sp
+The configuration directives can also be specified directly on the \fBchronyd\fP
+command line. In this case each argument is parsed as a new line and the
+configuration file is ignored.
+.sp
+While the number of supported directives is large, only a few of them are
+typically needed. See the \fBEXAMPLES\fP section for configuration in
+typical operating scenarios.
+.sp
+The configuration file might contain comment lines. A comment line is any line
+that starts with zero or more spaces followed by any one of the following
+characters: \fB!\fP, \fB;\fP, \fB#\fP, \fB%\fP. Any line with this format will be ignored.
+.SH "DIRECTIVES"
+.SS "Time sources"
+.sp
+\fBserver\fP \fIhostname\fP [\fIoption\fP]...
+.RS 4
+The \fBserver\fP directive specifies an NTP server which can be used as a time
+source. The client\-server relationship is strictly hierarchical: a client might
+synchronise its system time to that of the server, but the server\(cqs system time
+will never be influenced by that of a client.
+.sp
+The server can be specified by its hostname or IP address. If the hostname cannot
+be resolved on start, \fBchronyd\fP will try it again in increasing intervals, and
+also when the \fBonline\fP command is issued in \fBchronyc\fP.
+.sp
+The DNS record can change over time. The used address will be replaced with a
+newly resolved address when the server becomes unreachable (i.e. no valid
+response to last 8 requests), unsynchronised, a falseticker (i.e. does not
+agree with a majority of other sources), or the root distance is too large (the
+limit can be configured by the \fBmaxdistance\fP directive). The
+automatic replacement happens at most once per 30 minutes.
+.sp
+This directive can be used multiple times to specify multiple servers.
+.sp
+The directive supports the following options:
+.sp
+\fBminpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the minimum interval between requests sent to the server
+as a power of 2 in seconds. For example, \fBminpoll 5\fP would mean that the
+polling interval should not drop below 32 seconds. The default is 6 (64
+seconds), the minimum is \-7 (1/128th of a second), and the maximum is 24 (6
+months). Note that intervals shorter than 6 (64 seconds) should generally not
+be used with public servers on the Internet, because it might be considered
+abuse. A sub\-second interval will be enabled only when the server is reachable
+and the round\-trip delay is shorter than 10 milliseconds, i.e. the server
+should be in a local network.
+.RE
+.sp
+\fBmaxpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the maximum interval between requests sent to the server
+as a power of 2 in seconds. For example, \fBmaxpoll 9\fP indicates that the polling
+interval should stay at or below 9 (512 seconds). The default is 10 (1024
+seconds), the minimum is \-7 (1/128th of a second), and the maximum is 24 (6
+months).
+.RE
+.sp
+\fBiburst\fP
+.RS 4
+With this option, \fBchronyd\fP will start with a burst of 4\-8 requests in order to
+make the first update of the clock sooner. It will also repeat the burst every
+time the source is switched from the offline state to online with the
+\fBonline\fP command in \fBchronyc\fP.
+.RE
+.sp
+\fBburst\fP
+.RS 4
+With this option, \fBchronyd\fP will send a burst of up to 4 requests when it
+cannot get a good measurement from the
+server. The number of requests in the burst is limited by the current polling
+interval to keep the average interval at or above the minimum interval, i.e.
+the current interval needs to be at least two times longer than the minimum
+interval in order to allow a burst with two requests.
+.RE
+.sp
+\fBkey\fP \fIID\fP
+.RS 4
+The NTP protocol supports a message authentication code (MAC) to prevent
+computers having their system time upset by rogue packets being sent to them.
+The MAC is generated as a function of a key specified in the key file,
+which is specified by the \fBkeyfile\fP directive.
+.sp
+The \fBkey\fP option specifies which key (with an ID in the range 1 through 2^32\-1)
+should \fBchronyd\fP use to authenticate requests sent to the server and verify its
+responses. The server must have the same key for this number configured,
+otherwise no relationship between the computers will be possible.
+.sp
+If the server is running \fBntpd\fP and the output size of the hash function used
+by the key is longer than 160 bits (e.g. SHA256), the \fBversion\fP option needs to
+be set to 4 for compatibility.
+.RE
+.sp
+\fBnts\fP
+.RS 4
+This option enables authentication using the Network Time Security (NTS)
+mechanism. Unlike with the \fBkey\fP option, the server and client do not need to
+share a key in a key file. NTS has a Key Establishment (NTS\-KE) protocol using
+the Transport Layer Security (TLS) protocol to get the keys and cookies
+required by NTS for authentication of NTP packets.
+.RE
+.sp
+\fBcertset\fP \fIID\fP
+.RS 4
+This option specifies which set of trusted certificates should be used to verify
+the server\(cqs certificate when the \fBnts\fP option is enabled. Sets of certificates
+can be specified with the \fBntstrustedcerts\fP directive. The
+default set is 0, which by default contains certificates of the system\(cqs
+default trusted certificate authorities.
+.RE
+.sp
+\fBmaxdelay\fP \fIdelay\fP
+.RS 4
+\fBchronyd\fP uses the network round\-trip delay to the server to determine how
+accurate a particular measurement is likely to be. Long round\-trip delays
+indicate that the request, or the response, or both were delayed. If only one
+of the messages was delayed the measurement error is likely to be substantial.
+.sp
+For small variations in the round\-trip delay, \fBchronyd\fP uses a weighting scheme
+when processing the measurements. However, beyond a certain level of delay the
+measurements are likely to be so corrupted as to be useless. (This is
+particularly so on wireless networks and other slow links, where a long delay
+probably indicates a highly asymmetric delay caused by the response waiting
+behind a lot of packets related to a download of some sort).
+.sp
+If the user knows that round trip delays above a certain level should cause the
+measurement to be ignored, this level can be defined with the \fBmaxdelay\fP
+option. For example, \fBmaxdelay 0.3\fP would indicate that measurements with a
+round\-trip delay greater than 0.3 seconds should be ignored. The default value
+is 3 seconds and the maximum value is 1000 seconds.
+.RE
+.sp
+\fBmaxdelayratio\fP \fIratio\fP
+.RS 4
+This option is similar to the \fBmaxdelay\fP option above. \fBchronyd\fP keeps a record
+of the minimum round\-trip delay amongst the previous measurements that it has
+buffered. If a measurement has a round\-trip delay that is greater than the
+specified ratio times the minimum delay, it will be rejected. By default, this
+test is disabled.
+.RE
+.sp
+\fBmaxdelaydevratio\fP \fIratio\fP
+.RS 4
+If a measurement has a ratio of the increase in the round\-trip delay from the
+minimum delay amongst the previous measurements to the standard deviation of
+the previous measurements that is greater than the specified ratio, it will be
+rejected. The default is 10.0.
+.RE
+.sp
+\fBmaxdelayquant\fP \fIp\fP
+.RS 4
+This option disables the \fBmaxdelaydevratio\fP test and specifies the maximum
+acceptable delay as a quantile of the round\-trip delay instead of a function of
+the minimum delay amongst the buffered measurements. If a measurement has a
+round\-trip delay that is greater than a long\-term estimate of the \fIp\fP\-quantile,
+it will be rejected.
+.sp
+The specified \fIp\fP value should be between 0.05 and 0.95. For example,
+\fBmaxdelayquant 0.2\fP would indicate that only measurements with the lowest 20
+percent of round\-trip delays should be accepted. Note that it can take many
+measurements for the estimated quantile to reach the expected value. This
+option is intended for synchronisation in mostly static local networks with
+very short polling intervals and possibly combined with the \fBfilter\fP option.
+By default, this test is disabled in favour of the \fBmaxdelaydevratio\fP test.
+.RE
+.sp
+\fBmindelay\fP \fIdelay\fP
+.RS 4
+This option specifies a fixed minimum round\-trip delay to be used instead of
+the minimum amongst the previous measurements. This can be useful in networks
+with static configuration to improve the stability of corrections for
+asymmetric jitter, weighting of the measurements, and the \fBmaxdelayratio\fP and
+\fBmaxdelaydevratio\fP tests. The value should be set accurately in order to have a
+positive effect on the synchronisation.
+.RE
+.sp
+\fBasymmetry\fP \fIratio\fP
+.RS 4
+This option specifies the asymmetry of the network jitter on the path to the
+source, which is used to correct the measured offset according to the delay.
+The asymmetry can be between \-0.5 and +0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent from
+the source back. By default, \fBchronyd\fP estimates the asymmetry automatically.
+.RE
+.sp
+\fBoffset\fP \fIoffset\fP
+.RS 4
+This option specifies a correction (in seconds) which will be applied to
+offsets measured with this source. It\(cqs particularly useful to compensate for a
+known asymmetry in network delay or timestamping errors. For example, if
+packets sent to the source were on average delayed by 100 microseconds more
+than packets sent from the source back, the correction would be \-0.00005 (\-50
+microseconds). The default is 0.0.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+Set the minimum number of samples kept for this source. This overrides the
+\fBminsamples\fP directive.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+Set the maximum number of samples kept for this source. This overrides the
+\fBmaxsamples\fP directive.
+.RE
+.sp
+\fBfilter\fP \fIpolls\fP
+.RS 4
+This option enables a median filter to reduce noise in NTP measurements. The
+filter will process samples collected in the specified number of polls
+into a single sample. It is intended to be used with very short polling
+intervals in local networks where it is acceptable to generate a lot of NTP
+traffic.
+.RE
+.sp
+\fBoffline\fP
+.RS 4
+If the server will not be reachable when \fBchronyd\fP is started, the \fBoffline\fP
+option can be specified. \fBchronyd\fP will not try to poll the server until it is
+enabled to do so (by using the \fBonline\fP command in
+\fBchronyc\fP).
+.RE
+.sp
+\fBauto_offline\fP
+.RS 4
+With this option, the server will be assumed to have gone offline when sending
+a request fails, e.g. due to a missing route to the network. This option avoids
+the need to run the \fBoffline\fP command from \fBchronyc\fP
+when disconnecting the network link. (It will still be necessary to use the
+\fBonline\fP command when the link has been established, to
+enable measurements to start.)
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+Prefer this source over sources without the \fBprefer\fP option.
+.RE
+.sp
+\fBnoselect\fP
+.RS 4
+Never select this source. This is particularly useful for monitoring.
+.RE
+.sp
+\fBtrust\fP
+.RS 4
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+.RE
+.sp
+\fBrequire\fP
+.RS 4
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the \fBtrust\fP option this might be useful to allow a trusted
+authenticated source to be safely combined with unauthenticated sources in
+order to improve the accuracy of the clock. They can be selected and used for
+synchronisation only if they agree with the trusted and required source.
+.RE
+.sp
+\fBxleave\fP
+.RS 4
+This option enables the interleaved mode of NTP. It enables the server to
+respond with more accurate transmit timestamps (e.g. kernel or hardware
+timestamps), which cannot be contained in the transmitted packet itself and
+need to refer to a previous packet instead. This can significantly improve the
+accuracy and stability of the measurements.
+.sp
+The interleaved mode is compatible with servers that support only the basic
+mode. Note that even
+servers that support the interleaved mode might respond in the basic mode as
+the interleaved mode requires the servers to keep some state for each client
+and the state might be dropped when there are too many clients (e.g.
+\fBclientloglimit\fP is too small), or it might be overwritten
+by other clients that have the same IP address (e.g. computers behind NAT or
+someone sending requests with a spoofed source address).
+.sp
+The \fBxleave\fP option can be combined with the \fBpresend\fP option in order to
+shorten the interval in which the server has to keep the state to be able to
+respond in the interleaved mode.
+.RE
+.sp
+\fBpolltarget\fP \fItarget\fP
+.RS 4
+Target number of measurements to use for the regression algorithm which
+\fBchronyd\fP will try to maintain by adjusting the polling interval between
+\fBminpoll\fP and \fBmaxpoll\fP. A higher target makes \fBchronyd\fP prefer shorter polling
+intervals. The default is 8 and a useful range is from 6 to 60.
+.RE
+.sp
+\fBport\fP \fIport\fP
+.RS 4
+This option allows the UDP port on which the server understands NTP requests to
+be specified. For normal servers this option should not be required (the
+default is 123, the standard NTP port).
+.RE
+.sp
+\fBntsport\fP \fIport\fP
+.RS 4
+This option specifies the TCP port on which the server is listening for NTS\-KE
+connections when the \fBnts\fP option is enabled. The default is 4460.
+.RE
+.sp
+\fBpresend\fP \fIpoll\fP
+.RS 4
+If the timing measurements being made by \fBchronyd\fP are the only network data
+passing between two computers, you might find that some measurements are badly
+skewed due to either the client or the server having to do an ARP lookup on the
+other party prior to transmitting a packet. This is more of a problem with long
+sampling intervals, which might be similar in duration to the lifetime of entries
+in the ARP caches of the machines.
+.sp
+In order to avoid this problem, the \fBpresend\fP option can be used. It takes a
+single integer argument, which is the smallest polling interval for which an
+extra pair of NTP packets will be exchanged between the client and the server
+prior to the actual measurement. For example, with the following option
+included in a \fBserver\fP directive:
+.sp
+.if n .RS 4
+.nf
+.fam C
+presend 9
+.fam
+.fi
+.if n .RE
+.sp
+when the polling interval is 512 seconds or more, an extra NTP client packet
+will be sent to the server a short time (2 seconds) before making the actual
+measurement.
+.sp
+If the \fBpresend\fP option is used together with the \fBxleave\fP option, \fBchronyd\fP
+will send two extra packets instead of one.
+.RE
+.sp
+\fBminstratum\fP \fIstratum\fP
+.RS 4
+When the synchronisation source is selected from available sources, sources
+with lower stratum are normally slightly preferred. This option can be used to
+increase stratum of the source to the specified minimum, so \fBchronyd\fP will
+avoid selecting that source. This is useful with low\-stratum sources that are
+known to be unreliable or inaccurate and which should be used only when other
+sources are unreachable.
+.RE
+.sp
+\fBversion\fP \fIversion\fP
+.RS 4
+This option sets the NTP version of packets sent to the server. This can be
+useful when the server runs an old NTP implementation that does not respond to
+requests using a newer version. The default version depends on other options.
+If the \fBextfield\fP or \fBxleave\fP option is used, the default version is 4. If
+those options are not used and the \fBkey\fP option specifies a key using a hash
+function with output size longer than 160 bits (e.g. SHA256), the default
+version is 3 for compatibility with older \fBchronyd\fP servers. In other cases,
+the default version is 4.
+.RE
+.sp
+\fBcopy\fP
+.RS 4
+This option specifies that the server and client are closely related, their
+configuration does not allow a synchronisation loop to form between them, and
+the client is allowed to assume the reference ID and stratum of the server.
+This is useful when multiple instances of \f(CRchronyd\fP are running on one computer
+(e.g. for security or performance reasons), one primarily operating as a client
+to synchronise the system clock and other instances started with the \fB\-x\fP
+option to operate as NTP servers for other computers with their NTP clocks
+synchronised to the first instance.
+.RE
+.sp
+\fBextfield\fP \fItype\fP
+.RS 4
+This option enables an NTPv4 extension field specified by its type as a
+hexadecimal number. It will be included in requests sent to the server and
+processed in received responses if the server supports it. Note that some
+server implementations do not respond to requests containing an unknown
+extension field (\fBchronyd\fP as a server responded to such requests since
+version 2.0).
+.sp
+The following extension field can be enabled by this option:
+.sp
+\fIF323\fP
+.RS 4
+This is an experimental extension field for some improvements that were
+proposed for the next version of the NTP protocol (NTPv5). The field contains
+root delay and dispersion in higher resolution and a monotonic receive
+timestamp, which enables a frequency transfer between the server and client. It
+can significantly improve stability of the synchronization. Generally, it
+should be expected to work only between servers and clients running the same
+version of \fBchronyd\fP.
+.RE
+.RE
+.sp
+
+.RS 4
+.RE
+.RE
+.sp
+\fBpool\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The syntax of this directive is similar to that for the \fBserver\fP
+directive, except that it is used to specify a pool of NTP servers rather than
+a single NTP server. The pool name is expected to resolve to multiple addresses
+which might change over time.
+.sp
+This directive can be used multiple times to specify multiple pools.
+.sp
+All options valid in the \fBserver\fP directive can be used in this
+directive too. There is one option specific to the \fBpool\fP directive:
+.sp
+\fBmaxsources\fP \fIsources\fP
+.RS 4
+This option sets the desired number of sources to be used from the pool.
+\fBchronyd\fP will repeatedly try to resolve the name until it gets this number of
+sources responding to requests. The default value is 4 and the maximum value is
+16.
+.sp
+An example of the \fBpool\fP directive is
+.sp
+.if n .RS 4
+.nf
+.fam C
+pool pool.ntp.org iburst maxsources 3
+.fam
+.fi
+.if n .RE
+.RE
+.RE
+.sp
+\fBpeer\fP \fIhostname\fP [\fIoption\fP]...
+.RS 4
+The syntax of this directive is identical to that for the \fBserver\fP
+directive, except that it specifies a symmetric association with an NTP peer
+instead of a client/server association with an NTP server. A single symmetric
+association allows the peers to be both servers and clients to each other. This
+is mainly useful when the NTP implementation of the peer (e.g. \fBntpd\fP) supports
+ephemeral symmetric associations and does not need to be configured with an
+address of this host. \fBchronyd\fP does not support ephemeral associations.
+.sp
+This directive can be used multiple times to specify multiple peers.
+.sp
+The following options of the \fBserver\fP directive do not work in the \fBpeer\fP
+directive: \fBiburst\fP, \fBburst\fP, \fBnts\fP, \fBpresend\fP, \fBcopy\fP.
+.sp
+When using the \fBxleave\fP option, both peers must support and have enabled the
+interleaved mode, otherwise the synchronisation will work in one direction
+only.
+When a key is specified by the \fBkey\fP option to enable authentication, both
+peers must use the same key and the same key number.
+.sp
+Note that the symmetric mode is less secure than the client/server mode. A
+denial\-of\-service attack is possible on unauthenticated symmetric associations,
+i.e. when the peer was specified without the \fBkey\fP option. An attacker who does
+not see network traffic between two hosts, but knows that they are peering with
+each other, can periodically send them unauthenticated packets with spoofed
+source addresses in order to disrupt their NTP state and prevent them from
+synchronising to each other. When the association is authenticated, an attacker
+who does see the network traffic, but cannot prevent the packets from reaching
+the other host, can still disrupt the state by replaying old packets. The
+attacker has effectively the same power as a man\-in\-the\-middle attacker. A
+partial protection against this attack is implemented in \fBchronyd\fP, which can
+protect the peers if they are using the same polling interval and they never
+sent an authenticated packet with a timestamp from future, but it should not be
+relied on as it is difficult to ensure the conditions are met. If two hosts
+should be able to synchronise to each other in both directions, it is
+recommended to use two separate client/server associations (specified by the
+\fBserver\fP directive on both hosts) instead.
+.RE
+.sp
+\fBinitstepslew\fP \fIstep\-threshold\fP [\fIhostname\fP]...
+.RS 4
+(This directive is deprecated in favour of the \fBmakestep\fP
+directive.)
+.sp
+The purpose of the \fBinitstepslew\fP directive is to allow \fBchronyd\fP to make a
+rapid measurement of the system clock error at boot time, and to correct the
+system clock by stepping before normal operation begins. Since this would
+normally be performed only at an appropriate point in the system boot sequence,
+no other software should be adversely affected by the step.
+.sp
+If the correction required is less than a specified threshold, a slew is used
+instead. This makes it safer to restart \fBchronyd\fP whilst the system is in
+normal operation.
+.sp
+The \fBinitstepslew\fP directive takes a threshold and a list of NTP servers as
+arguments. Each of the servers is rapidly polled several times, and a majority
+voting mechanism used to find the most likely range of system clock error that
+is present. A step or slew is applied to the system clock to correct this
+error. \fBchronyd\fP then enters its normal operating mode.
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 30 foo.example.net bar.example.net baz.example.net
+.fam
+.fi
+.if n .RE
+.sp
+where 3 NTP servers are used to make the measurement. The \fI30\fP indicates that
+if the system\(cqs error is found to be 30 seconds or less, a slew will be used to
+correct it; if the error is above 30 seconds, a step will be used.
+.sp
+The \fBinitstepslew\fP directive can also be used in an isolated LAN environment,
+where the clocks are set manually. The most stable computer is chosen as the
+primary server and the other computers are its clients. If each of the clients
+is configured with the \fBlocal\fP directive, the server can be set up
+with an \fBinitstepslew\fP directive which references some or all of the clients.
+Then, if the server machine has to be rebooted, the clients can be relied on to
+act analogously to a flywheel and preserve the time for a short period while
+the server completes its reboot.
+.sp
+The \fBinitstepslew\fP directive is functionally similar to a combination of the
+\fBmakestep\fP and \fBserver\fP directives with the \fBiburst\fP
+option. The main difference is that the \fBinitstepslew\fP servers are used only
+before normal operation begins and that the foreground \fBchronyd\fP process waits
+for \fBinitstepslew\fP to finish before exiting. This prevent programs started in
+the boot sequence after \fBchronyd\fP from reading the clock before it has been
+stepped. With the \fBmakestep\fP directive, the
+\fBwaitsync\fP command of \fBchronyc\fP can be used instead.
+.RE
+.sp
+\fBrefclock\fP \fIdriver\fP \fIparameter\fP[:\fIoption\fP]... [\fIoption\fP]...
+.RS 4
+The \fBrefclock\fP directive specifies a hardware reference clock to be used as a
+time source. It has two mandatory parameters, a driver name and a
+driver\-specific parameter. The two parameters are followed by zero or more
+refclock options. Some drivers have special options, which can be appended to
+the driver\-specific parameter using the \fB:\fP character.
+.sp
+This directive can be used multiple times to specify multiple reference clocks.
+.sp
+There are four drivers included in \fBchronyd\fP:
+.sp
+\fBPPS\fP
+.RS 4
+Driver for the kernel PPS (pulse per second) API. The parameter is the path to
+the PPS device (typically \fI/dev/pps?\fP). As PPS refclocks do not supply full
+time, another time source (e.g. NTP server or non\-PPS refclock) is needed to
+complete samples from the PPS refclock. An alternative is to enable the
+\fBlocal\fP directive to allow synchronisation with some unknown but
+constant offset. The driver supports the following option:
+.sp
+\fBclear\fP
+.RS 4
+By default, the PPS refclock uses assert events (rising edge) for
+synchronisation. With this option, it will use clear events (falling edge)
+instead.
+.RE
+.RE
+.sp
+
+.RS 4
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock PPS /dev/pps0 lock NMEA refid GPS1
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.2 refid NMEA noselect
+refclock PPS /dev/pps1:clear refid GPS2
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBSOCK\fP
+.RS 4
+Unix domain socket driver. This driver uses a datagram socket to receive
+samples from another application running on the system. The parameter is the
+path to the socket, which \fBchronyd\fP will create on start. The format of the
+messages is described in the \fIrefclock_sock.c\fP file in the chrony source code.
+.sp
+An application which supports the SOCK protocol is the \fBgpsd\fP daemon. It can
+provide accurate measurements using the receiver\(cqs PPS signal, and since
+version 3.25 also (much less accurate) measurements based on the timing of
+serial data (e.g. NMEA), which can be useful when the receiver does not provide
+a PPS signal, or it cannot be connected to the computer. The paths where \fBgpsd\fP
+expects the sockets to be created by \fBchronyd\fP are described in the \fBgpsd(8)\fP
+man page. Note that \fBgpsd\fP needs to be started after \fBchronyd\fP in order to
+connect to the socket.
+.sp
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS1 poll 2 filter 4
+refclock SOCK /var/run/chrony.clk.ttyUSB0.sock refid GPS2 offset 0.2 delay 0.1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBSHM\fP
+.RS 4
+NTP shared memory driver. This driver implements the protocol of the \fBntpd\fP
+driver type 28. It is functionally similar to the SOCK driver, but uses a
+shared memory segment instead of a socket. The parameter is the unit number,
+typically a small number like 0, 1, 2, or 3, from which is derived the key of
+the memory segment as 0x4e545030 + unit.
+.sp
+The driver supports the following option:
+.sp
+\fBperm\fP=\fImode\fP
+.RS 4
+This option specifies the permissions of the shared memory segment created by
+\fBchronyd\fP. They are specified as a numeric mode. The default value is 0600
+(read\-write access for owner only).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Unlike with the SOCK driver, there is no prescribed order of starting \fBchronyd\fP
+and the program providing measurements. Both are expected to create the memory
+segment if it does not exist. \fBchronyd\fP will attach to an existing segment even
+if it has a different owner than root or different permissions than the
+permissions specified by the \fBperm\fP option. The segment needs to be created
+before untrusted applications or users can execute code to prevent an attacker
+from feeding \fBchronyd\fP with false measurements. The owner and permissions of
+the segment can be verified with the \fBipcs \-m\fP command. For this reason, the
+SHM driver is deprecated in favor of SOCK.
+.sp
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock SHM 0 poll 3 refid GPS1
+refclock SHM 1:perm=0644 refid GPS2
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBPHC\fP
+.RS 4
+PTP hardware clock (PHC) driver. The parameter is the path to the device of
+the PTP clock which should be used as a time source. If the clock is kept in
+TAI instead of UTC (e.g. it is synchronised by a PTP daemon), the current
+UTC\-TAI offset needs to be specified by the \fBoffset\fP option. Alternatively, the
+\fBpps\fP refclock option can be enabled to treat the PHC as a PPS refclock, using
+only the sub\-second offset for synchronisation. The driver supports the
+following options:
+.sp
+\fBnocrossts\fP
+.RS 4
+This option disables use of precise cross timestamping.
+.RE
+.sp
+\fBextpps\fP
+.RS 4
+This option enables a PPS mode in which the PTP clock is timestamping pulses
+of an external PPS signal connected to the clock. The clock does not need to be
+synchronised, but another time source is needed to complete the PPS samples.
+Note that some PTP clocks cannot be configured to timestamp only assert or
+clear events, and it is necessary to use the \fBwidth\fP option to filter wrong
+PPS samples.
+.RE
+.sp
+\fBpin\fP=\fIindex\fP
+.RS 4
+This option specifies the index of the pin which should be enabled for the
+PPS timestamping. If the PHC does not have configurable pins (i.e. the channel
+function is fixed), the index needs to be set to \-1 to disable the pin
+configuration. The default value is 0.
+.RE
+.sp
+\fBchannel\fP=\fIindex\fP
+.RS 4
+This option specifies the index of the channel for the PPS mode. The default
+value is 0.
+.RE
+.sp
+\fBclear\fP
+.RS 4
+This option enables timestamping of clear events (falling edge) instead of
+assert events (rising edge) in the PPS mode. This may not work with some
+clocks.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+refclock PHC /dev/ptp0 poll 0 dpoll \-2 offset \-37
+refclock PHC /dev/ptp1:nocrossts poll 3 pps
+refclock PHC /dev/ptp2:extpps:pin=1 width 0.2 poll 2
+.fam
+.fi
+.if n .RE
+.RE
+.RE
+.sp
+
+.RS 4
+The \fBrefclock\fP directive supports the following options:
+.sp
+\fBpoll\fP \fIpoll\fP
+.RS 4
+Timestamps produced by refclock drivers are not used immediately, but they are
+stored and processed by a median filter in the polling interval specified by
+this option. This is defined as a power of 2 and can be negative to specify a
+sub\-second interval. The default is 4 (16 seconds). A shorter interval allows
+\fBchronyd\fP to react faster to changes in the frequency of the system clock, but
+it might have a negative effect on its accuracy if the samples have a lot of
+jitter.
+.RE
+.sp
+\fBdpoll\fP \fIdpoll\fP
+.RS 4
+Some drivers do not listen for external events and try to produce samples in
+their own polling interval. This is defined as a power of 2 and can be negative
+to specify a sub\-second interval. The default is 0 (1 second).
+.RE
+.sp
+\fBrefid\fP \fIrefid\fP
+.RS 4
+This option is used to specify the reference ID of the refclock, as up to four
+ASCII characters. The default reference ID is composed from the first three
+characters of the driver name and the number of the refclock. Each refclock
+must have a unique reference ID.
+.RE
+.sp
+\fBlock\fP \fIrefid\fP
+.RS 4
+This option can be used to lock a PPS refclock to another refclock, which is
+specified by its reference ID. In this mode received PPS samples are paired
+directly with raw samples from the specified refclock.
+.RE
+.sp
+\fBrate\fP \fIrate\fP
+.RS 4
+This option sets the rate of the pulses in the PPS signal (in Hz). This option
+controls how the pulses will be completed with real time. To actually receive
+more than one pulse per second, a negative \fBdpoll\fP has to be specified (\-3 for
+a 5Hz signal). The default is 1.
+.RE
+.sp
+\fBmaxlockage\fP \fIpulses\fP
+.RS 4
+This option specifies in number of pulses how old can be samples from the
+refclock specified by the \fBlock\fP option to be paired with the pulses.
+Increasing this value is useful when the samples are produced at a lower rate
+than the pulses. The default is 2.
+.RE
+.sp
+\fBwidth\fP \fIwidth\fP
+.RS 4
+This option specifies the width of the pulses (in seconds). It is used to
+filter PPS samples when the driver provides samples for both rising and falling
+edges. Note that it reduces the maximum allowed error of the time source which
+completes the PPS samples. If the duty cycle is configurable, 50% should be
+preferred in order to maximise the allowed error.
+.RE
+.sp
+\fBpps\fP
+.RS 4
+This options forces \fBchronyd\fP to treat any refclock (e.g. SHM or PHC) as a PPS
+refclock. This can be useful when the refclock provides time with a variable
+offset of a whole number of seconds (e.g. it uses TAI instead of UTC). Another
+time source is needed to complete samples from the refclock.
+.RE
+.sp
+\fBoffset\fP \fIoffset\fP
+.RS 4
+This option can be used to compensate for a constant error. The specified
+offset (in seconds) is applied to all samples produced by the reference clock.
+The default is 0.0.
+.RE
+.sp
+\fBdelay\fP \fIdelay\fP
+.RS 4
+This option sets the NTP delay of the source (in seconds). Half of this value
+is included in the maximum assumed error which is used in the source selection
+algorithm. Increasing the delay is useful to avoid having no majority in the
+source selection or to make it prefer other sources. The default is 1e\-9 (1
+nanosecond).
+.RE
+.sp
+\fBstratum\fP \fIstratum\fP
+.RS 4
+This option sets the NTP stratum of the refclock. This can be useful when the
+refclock provides time with a stratum other than 0. The default is 0.
+.RE
+.sp
+\fBprecision\fP \fIprecision\fP
+.RS 4
+This option sets the precision of the reference clock (in seconds). The default
+value is the estimated precision of the system clock.
+.RE
+.sp
+\fBmaxdispersion\fP \fIdispersion\fP
+.RS 4
+Maximum allowed dispersion for filtered samples (in seconds). Samples with
+larger estimated dispersion are ignored. By default, this limit is disabled.
+.RE
+.sp
+\fBfilter\fP \fIsamples\fP
+.RS 4
+This option sets the length of the median filter which is used to reduce the
+noise in the measurements. With each poll about 40 percent of the stored
+samples are discarded and one final sample is calculated as an average of the
+remaining samples. If the length is 4 or more, at least 4 samples have to be
+collected between polls. For lengths below 4, the filter has to be full. The
+default is 64. With drivers that perform their own polling (PPS, PHC, SHM), the
+maximum value is adjusted to the number of driver polls per source poll, i.e.
+2^(\fIpoll\fP \- \fIdpoll\fP).
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+Prefer this source over sources without the prefer option.
+.RE
+.sp
+\fBnoselect\fP
+.RS 4
+Never select this source. This is useful for monitoring or with sources which
+are not very accurate, but are locked with a PPS refclock.
+.RE
+.sp
+\fBtrust\fP
+.RS 4
+Assume time from this source is always true. It can be rejected as a
+falseticker in the source selection only if another source with this option
+does not agree with it.
+.RE
+.sp
+\fBrequire\fP
+.RS 4
+Require that at least one of the sources specified with this option is
+selectable (i.e. recently reachable and not a falseticker) before updating the
+clock. Together with the \fBtrust\fP option this can be useful to allow a trusted,
+but not very precise, reference clock to be safely combined with
+unauthenticated NTP sources in order to improve the accuracy of the clock. They
+can be selected and used for synchronisation only if they agree with the
+trusted and required source.
+.RE
+.sp
+\fBtai\fP
+.RS 4
+This option indicates that the reference clock keeps time in TAI instead of UTC
+and that \fBchronyd\fP should correct its offset by the current TAI\-UTC offset. The
+\fBleapsectz\fP directive must be used with this option and the
+database must be kept up to date in order for this correction to work as
+expected. This option does not make sense with PPS refclocks.
+.RE
+.sp
+\fBlocal\fP
+.RS 4
+This option specifies that the reference clock is an unsynchronised clock which
+is more stable than the system clock (e.g. TCXO, OCXO, or atomic clock) and
+it should be used as a local standard to stabilise the system clock. The
+refclock will bypass the source selection. There should be at most one refclock
+specified with this option and it should have the shortest polling interval
+among all configured sources.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+Set the minimum number of samples kept for this source. This overrides the
+\fBminsamples\fP directive.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+Set the maximum number of samples kept for this source. This overrides the
+\fBmaxsamples\fP directive.
+.RE
+.RE
+.sp
+\fBmanual\fP
+.RS 4
+The \fBmanual\fP directive enables support at run\-time for the
+\fBsettime\fP command in \fBchronyc\fP. If no \fBmanual\fP
+directive is included, any attempt to use the \fBsettime\fP command in \fBchronyc\fP
+will be met with an error message.
+.sp
+Note that the \fBsettime\fP command can be enabled at run\-time using
+the \fBmanual\fP command in \fBchronyc\fP. (The idea of the two
+commands is that the \fBmanual\fP command controls the manual clock driver\(cqs
+behaviour, whereas the \fBsettime\fP command allows samples of manually entered
+time to be provided.)
+.RE
+.sp
+\fBacquisitionport\fP \fIport\fP
+.RS 4
+By default, \fBchronyd\fP as an NTP client opens a new socket for each request with
+the source port chosen randomly by the operating system. The \fBacquisitionport\fP
+directive can be used to specify the source port and use only one socket (per
+IPv4 or IPv6 address family) for all configured servers. This can be useful for
+getting through some firewalls. It should not be used if not necessary as there
+is a small impact on security of the client. If set to 0, the source port of
+the permanent socket will be chosen randomly by the operating system.
+.sp
+It can be set to the same port as is used by the NTP server (which can be
+configured with the \fBport\fP directive) to use only one socket for all
+NTP packets.
+.sp
+An example of the \fBacquisitionport\fP directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+acquisitionport 1123
+.fam
+.fi
+.if n .RE
+.sp
+This would change the source port used for client requests to UDP port 1123.
+You could then persuade the firewall administrator to open that port.
+.RE
+.sp
+\fBbindacqaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindacqaddress\fP directive specifies a local IP address to which
+\fBchronyd\fP will bind its NTP and NTS\-KE client sockets. The syntax is similar to
+the \fBbindaddress\fP and \fBbindcmdaddress\fP
+directives.
+.sp
+For each of the IPv4 and IPv6 protocols, only one \fBbindacqaddress\fP directive
+can be specified.
+.RE
+.sp
+\fBbindacqdevice\fP \fIinterface\fP
+.RS 4
+The \fBbindacqdevice\fP directive binds the client sockets to a network device
+specified by the interface name. This can be useful when the local address is
+dynamic, or to enable an NTP source specified with a link\-local IPv6 address.
+This directive can specify only one interface and it is supported on Linux
+only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindacqdevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdscp\fP \fIpoint\fP
+.RS 4
+The \fBdscp\fP directive sets the Differentiated Services Code Point (DSCP) in
+transmitted NTP packets to the specified value. It can improve stability of NTP
+measurements in local networks where switches or routers are configured to
+prioritise forwarding of packets with specific DSCP values. The default value
+is 0 and the maximum value is 63.
+.sp
+An example of the directive (setting the Expedited Forwarding class) is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+dscp 46
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdumpdir\fP \fIdirectory\fP
+.RS 4
+To compute the rate of gain or loss of time, \fBchronyd\fP has to store a
+measurement history for each of the time sources it uses.
+.sp
+All supported systems, with the exception of macOS 10.12 and earlier, have
+operating system support for setting the rate of gain or loss to compensate for
+known errors.
+(On macOS 10.12 and earlier, \fBchronyd\fP must simulate such a capability by
+periodically slewing the system clock forwards or backwards by a suitable amount
+to compensate for the error built up since the previous slew.)
+.sp
+For such systems, it is possible to save the measurement history across
+restarts of \fBchronyd\fP (assuming no changes are made to the system clock
+behaviour whilst it is not running). The \fBdumpdir\fP directive defines the
+directory where the measurement histories are saved when \fBchronyd\fP exits,
+or the \fBdump\fP command in \fBchronyc\fP is issued.
+.sp
+If the directory does not exist, it will be created automatically.
+.sp
+The \fB\-r\fP option of \fBchronyd\fP enables loading of the dump files on start. All
+dump files found in the directory will be removed after start, even if the \fB\-r\fP
+option is not present.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+dumpdir @CHRONYRUNDIR@
+.fam
+.fi
+.if n .RE
+.sp
+A source whose IP address is \fI1.2.3.4\fP would have its measurement history saved
+in the file \fI@CHRONYRUNDIR@/1.2.3.4.dat\fP. History of reference clocks is saved
+to files named by their reference ID in form of \fIrefid:XXXXXXXX.dat\fP.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+The \fBmaxsamples\fP directive sets the default maximum number of samples that
+\fBchronyd\fP should keep for each source. This setting can be overridden for
+individual sources in the \fBserver\fP and \fBrefclock\fP
+directives. The default value is 0, which disables the configurable limit. The
+useful range is 4 to 64.
+.sp
+As a special case, setting \fBmaxsamples\fP to 1 disables frequency tracking in
+order to make the sources immediately selectable with only one sample. This can
+be useful when \fBchronyd\fP is started with the \fB\-q\fP or \fB\-Q\fP option.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+The \fBminsamples\fP directive sets the default minimum number of samples that
+\fBchronyd\fP should keep for each source. This setting can be overridden for
+individual sources in the \fBserver\fP and \fBrefclock\fP
+directives. The default value is 6. The useful range is 4 to 64.
+.sp
+Forcing \fBchronyd\fP to keep more samples than it would normally keep reduces
+noise in the estimated frequency and offset, but slows down the response to
+changes in the frequency and offset of the clock. The offsets in the
+\fBtracking\fP and
+\fBsourcestats\fP reports (and the \fItracking.log\fP and
+\fIstatistics.log\fP files) may be smaller than the actual offsets.
+.RE
+.sp
+\fBntsdumpdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies a directory for the client to save NTS cookies it
+received from the server in order to avoid making an NTS\-KE request when
+\fBchronyd\fP is started again. The cookies are saved separately for each NTP
+source in files named by the IP address of the NTS\-KE server (e.g.
+\fI1.2.3.4.nts\fP). By default, the client does not save the cookies.
+.sp
+If the directory does not exist, it will be created automatically.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsdumpdir @CHRONYVARDIR@
+.fam
+.fi
+.if n .RE
+.sp
+This directory is used also by the NTS server to save keys.
+.RE
+.sp
+\fBntsrefresh\fP \fIinterval\fP
+.RS 4
+This directive specifies the maximum interval between NTS\-KE handshakes (in
+seconds) in order to refresh the keys authenticating NTP packets. The default
+value is 2419200 (4 weeks) and the maximum value is 2^31\-1 (68 years).
+.sp
+The interval must be longer than polling intervals of all configured NTP
+sources using NTS, otherwise the source with a longer polling interval will
+refresh the keys on each poll and no NTP packets will be exchanged.
+.RE
+.sp
+\fBntstrustedcerts\fP [\fIset\-ID\fP] \fIfile\fP|\fIdirectory\fP
+.RS 4
+This directive specifies a file or directory containing certificates (in the
+PEM format) of trusted certificate authorities (CA) which can be used to
+verify certificates of NTS servers.
+.sp
+The optional \fIset\-ID\fP argument is a number in the range 0 through 2^32\-1, which
+selects the set of certificates where certificates from the specified file
+or directory are added. The default ID is 0, which is a set containing the
+system\(cqs default trusted CAs (unless the \fBnosystemcert\fP directive is present).
+All other sets are empty by default. A set of certificates can be selected for
+verification of an NTS server by the \fBcertset\fP option in the \fBserver\fP or \fBpool\fP
+directive.
+.sp
+This directive can be used multiple times to specify one or more sets of
+trusted certificates, each containing certificates from one or more files
+and/or directories.
+.sp
+It is not necessary to restart \fBchronyd\fP in order to reload the certificates if
+they change (e.g. after a renewal).
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntstrustedcerts /etc/pki/nts/foo.crt
+ntstrustedcerts 1 /etc/pki/nts/bar.crt
+ntstrustedcerts 1 /etc/pki/nts/baz.crt
+ntstrustedcerts 2 /etc/pki/nts/qux.crt
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBnosystemcert\fP
+.RS 4
+This directive disables the system\(cqs default trusted CAs. Only certificates
+specified by the \fBntstrustedcerts\fP directive will be trusted.
+.RE
+.sp
+\fBnocerttimecheck\fP \fIlimit\fP
+.RS 4
+This directive disables the checks of the activation and expiration times of
+certificates for the specified number of clock updates. It allows the NTS
+authentication mechanism to be used on computers which start with wrong time
+(e.g. due to not having an RTC or backup battery). Disabling the time checks
+has important security implications and should be used only as a last resort,
+preferably with a minimal number of trusted certificates. The default value is
+0, which means the time checks are always enabled.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+nocerttimecheck 1
+.fam
+.fi
+.if n .RE
+.sp
+This would disable the time checks until the clock is updated for the first
+time, assuming the first update corrects the clock and later checks can work
+with correct time.
+.RE
+.sp
+\fBrefresh\fP \fIinterval\fP
+.RS 4
+This directive specifies the interval (in seconds) between refreshing IP
+addresses of NTP sources specified by hostname. If the hostname no longer
+resolves to the currently used address, it will be replaced with one of the new
+addresses to avoid using a server which is no longer intended for service, even
+if it is still responding correctly and would not be replaced as unreachable.
+Only one source is refreshed at a time. The default value is 1209600 (2 weeks)
+and the maximum value is 2^31\-1 (68 years). A value of 0 disables the periodic
+refreshment.
+.sp
+The \fBrefresh\fP command can be used to refresh all
+sources immediately.
+.RE
+.SS "Source selection"
+.sp
+\fBauthselectmode\fP \fImode\fP
+.RS 4
+NTP sources can be specified with the \fBkey\fP or \fBnts\fP option to enable
+authentication to limit the impact of man\-in\-the\-middle attacks. The
+attackers can drop or delay NTP packets (up to the \fBmaxdelay\fP and
+\fBmaxdistance\fP limits), but they cannot modify the timestamps
+contained in the packets. The attack can cause only a limited slew or step, and
+also cause the clock to run faster or slower than real time (up to double of
+the \fBmaxdrift\fP limit).
+.sp
+When authentication is enabled for an NTP source, it is important to disable
+unauthenticated NTP sources which could be exploited in the attack, e.g. if
+they are not reachable only over a trusted network. Alternatively, the source
+selection can be configured with the \fBrequire\fP and \fBtrust\fP options to
+synchronise to the unauthenticated sources only if they agree with the
+authenticated sources and might have a positive impact on the accuracy of the
+clock. Note that in this case the impact of the attack is higher. The attackers
+cannot cause an arbitrarily large step or slew, but they have more control over
+the frequency of the clock and can cause \fBchronyd\fP to report false information,
+e.g. a significantly smaller root delay and dispersion.
+.sp
+This directive determines the default selection options for authenticated and
+unauthenticated sources in order to simplify the configuration with the
+configuration file and \fBchronyc\fP commands. It sets a policy for authentication.
+.sp
+Sources specified with the \fBnoselect\fP option are ignored (not counted as either
+authenticated or unauthenticated), and they always have only the selection
+options specified in the configuration.
+.sp
+There are four modes:
+.sp
+\fBrequire\fP
+.RS 4
+Authentication is strictly required for NTP sources in this mode. If any
+unauthenticated NTP sources are specified, they will automatically get the
+\fBnoselect\fP option to prevent them from being selected for synchronisation.
+.RE
+.sp
+\fBprefer\fP
+.RS 4
+In this mode, authentication is optional and preferred. If it is enabled for at
+least one NTP source, all unauthenticated NTP sources will get the \fBnoselect\fP
+option.
+.RE
+.sp
+\fBmix\fP
+.RS 4
+In this mode, authentication is optional and synchronisation to a mix of
+authenticated and unauthenticated NTP sources is allowed. If both authenticated
+and unauthenticated NTP sources are specified, all authenticated NTP sources
+and reference clocks will get the \fBrequire\fP and \fBtrust\fP options to prevent
+synchronisation to unauthenticated NTP sources if they do not agree with a
+majority of the authenticated sources and reference clocks. This is the default
+mode.
+.RE
+.sp
+\fBignore\fP
+.RS 4
+In this mode, authentication is ignored in the source selection. All sources
+will have only the selection options that were specified in the configuration
+file, or \fBchronyc\fP command. This was the behaviour of \fBchronyd\fP in versions
+before 4.0.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+As an example, the following configuration using the default \fBmix\fP mode:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net nts
+server bar.example.net nts
+server baz.example.net
+refclock SOCK /var/run/chrony.ttyS0.sock
+.fam
+.fi
+.if n .RE
+.sp
+is equivalent to the following configuration using the \fBignore\fP mode:
+.sp
+.if n .RS 4
+.nf
+.fam C
+authselectmode ignore
+server foo.example.net nts require trust
+server bar.example.net nts require trust
+server baz.example.net
+refclock /var/run/chrony.ttyS0.sock require trust
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcombinelimit\fP \fIlimit\fP
+.RS 4
+When \fBchronyd\fP has multiple sources available for synchronisation, it has to
+select one source as the synchronisation source. The measured offsets and
+frequencies of the system clock relative to the other sources, however, can be
+combined with the selected source to improve the accuracy of the system clock.
+.sp
+The \fBcombinelimit\fP directive limits which sources are included in the combining
+algorithm. Their synchronisation distance has to be shorter than the distance
+of the selected source multiplied by the value of the limit. Also, their
+measured frequencies have to be close to the frequency of the selected source.
+If the selected source was specified with the \fBprefer\fP option, it can be
+combined only with other sources specified with this option.
+.sp
+By default, the limit is 3. Setting the limit to 0 effectively disables the
+source combining algorithm and only the selected source will be used to control
+the system clock.
+.RE
+.sp
+\fBmaxdistance\fP \fIdistance\fP
+.RS 4
+The \fBmaxdistance\fP directive sets the maximum root distance of a source to be
+acceptable for synchronisation of the clock. Sources that have a distance
+larger than the specified distance will be rejected. The distance estimates the
+maximum error of the source. It includes the root dispersion and half of the
+root delay (round\-trip time) accumulated on the path to the primary source.
+.sp
+By default, the maximum root distance is 3 seconds.
+.sp
+Setting \fBmaxdistance\fP to a larger value can be useful to allow synchronisation
+with a server that only has a very infrequent connection to its sources and can
+accumulate a large dispersion between updates of its clock.
+.RE
+.sp
+\fBmaxjitter\fP \fIjitter\fP
+.RS 4
+The \fBmaxjitter\fP directive sets the maximum allowed jitter of the sources to not
+be rejected by the source selection algorithm. This prevents synchronisation
+with sources that have a small root distance, but their time is too variable.
+.sp
+By default, the maximum jitter is 1 second.
+.RE
+.sp
+\fBminsources\fP \fIsources\fP
+.RS 4
+The \fBminsources\fP directive sets the minimum number of sources that need to be
+considered as selectable in the source selection algorithm before the local
+clock is updated. The default value is 1.
+.sp
+Setting this option to a larger number can be used to improve the reliability.
+More sources will have to agree with each other and the clock will not be
+updated when only one source (which could be serving incorrect time) is
+reachable.
+.RE
+.sp
+\fBreselectdist\fP \fIdistance\fP
+.RS 4
+When \fBchronyd\fP selects a synchronisation source from available sources, it
+will prefer the one with the shortest synchronisation distance. However, to
+avoid frequent reselecting when there are sources with similar distance, a
+fixed distance is added to the distance for sources that are currently not
+selected. This can be set with the \fBreselectdist\fP directive. By default, the
+distance is 100 microseconds.
+.RE
+.sp
+\fBstratumweight\fP \fIdistance\fP
+.RS 4
+The \fBstratumweight\fP directive sets how much distance should be added per
+stratum to the synchronisation distance when \fBchronyd\fP selects the
+synchronisation source from available sources.
+.sp
+By default, the weight is 0.001 seconds. This means that the stratum of the sources
+in the selection process matters only when the differences between the
+distances are in milliseconds.
+.RE
+.SS "System clock"
+.sp
+\fBclockprecision\fP \fIprecision\fP
+.RS 4
+The \fBclockprecision\fP directive specifies the precision of the system clock (in
+seconds). It is used by \fBchronyd\fP to estimate the minimum noise in NTP
+measurements and randomise low\-order bits of timestamps in NTP responses. By
+default, the precision is measured on start as the minimum time to read the
+clock.
+.sp
+The measured value works well in most cases. However, it generally
+overestimates the precision and it can be sensitive to the CPU speed, which can
+change over time to save power. In some cases with a high\-precision clocksource
+(e.g. the Time Stamp Counter of the CPU) and hardware timestamping, setting the
+precision on the server to a smaller value can improve stability of clients\*(Aq
+NTP measurements. The server\(cqs precision is reported on clients by the
+\fBntpdata\fP command.
+.sp
+An example setting the precision to 8 nanoseconds is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clockprecision 8e\-9
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcorrtimeratio\fP \fIratio\fP
+.RS 4
+When \fBchronyd\fP is slewing the system clock to correct an offset, the rate at
+which it is slewing adds to the frequency error of the clock. On all supported
+systems, with the exception of macOS 12 and earlier, this rate can be
+controlled.
+.sp
+The \fBcorrtimeratio\fP directive sets the ratio between the duration in which the
+clock is slewed for an average correction according to the source history and
+the interval in which the corrections are done (usually the NTP polling
+interval). Corrections larger than the average take less time and smaller
+corrections take more time, the amount of the correction and the correction
+time are inversely proportional.
+.sp
+Increasing \fBcorrtimeratio\fP improves the overall frequency error of the system
+clock, but increases the overall time error as the corrections take longer.
+.sp
+By default, the ratio is set to 3, the time accuracy of the clock is preferred
+over its frequency accuracy.
+.sp
+The maximum allowed slew rate can be set by the \fBmaxslewrate\fP
+directive. The current remaining correction is shown in the
+\fBtracking\fP report as the \fBSystem time\fP value.
+.RE
+.sp
+\fBdriftfile\fP \fIfile\fP
+.RS 4
+One of the main activities of the \fBchronyd\fP program is to work out the rate at
+which the system clock gains or loses time relative to real time.
+.sp
+Whenever \fBchronyd\fP computes a new value of the gain or loss rate, it is desirable
+to record it somewhere. This allows \fBchronyd\fP to begin compensating the system
+clock at that rate whenever it is restarted, even before it has had a chance to
+obtain an equally good estimate of the rate during the new run. (This process
+can take many minutes, at least.)
+.sp
+The \fBdriftfile\fP directive allows a file to be specified into which \fBchronyd\fP
+can store the rate information. Two parameters are recorded in the file. The
+first is the rate at which the system clock gains or loses time, expressed in
+parts per million, with gains positive. Therefore, a value of 100.0 indicates
+that when the system clock has advanced by a second, it has gained 100
+microseconds in reality (so the true time has only advanced by 999900
+microseconds). The second is an estimate of the error bound around the first
+value in which the true rate actually lies.
+.sp
+An example of the driftfile directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+driftfile @CHRONYVARDIR@/drift
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBfallbackdrift\fP \fImin\-interval\fP \fImax\-interval\fP
+.RS 4
+Fallback drifts are long\-term averages of the system clock drift calculated
+over exponentially increasing intervals. They are used to avoid quickly
+drifting away from true time when the clock was not updated for a longer period
+of time and there was a short\-term deviation in the drift before the updates
+stopped.
+.sp
+The directive specifies the minimum and maximum interval since the last clock
+update to switch between fallback drifts. They are defined as a power of 2 (in
+seconds). The syntax is as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+fallbackdrift 16 19
+.fam
+.fi
+.if n .RE
+.sp
+In this example, the minimum interval is 16 (18 hours) and the maximum interval is
+19 (6 days). The system clock frequency will be set to the first fallback 18
+hours after last clock update, to the second after 36 hours, and so on. This
+might be a good setting to cover frequency changes due to daily and weekly
+temperature fluctuations. When the frequency is set to a fallback, the state of
+the clock will change to \(oqNot synchronised\(cq.
+.sp
+By default (or if the specified maximum or minimum is 0), no fallbacks are used
+and the clock frequency changes only with new measurements from NTP sources,
+reference clocks, or manual input.
+.RE
+.sp
+\fBleapsecmode\fP \fImode\fP
+.RS 4
+A leap second is an adjustment that is occasionally applied to UTC to keep it
+close to the mean solar time. When a leap second is inserted, the last day of
+June or December has an extra second 23:59:60.
+.sp
+For computer clocks that is a problem. The Unix time is defined as number of
+seconds since 00:00:00 UTC on 1 January 1970 without leap seconds. The system
+clock cannot have time 23:59:60, every minute has 60 seconds and every day has
+86400 seconds by definition. The inserted leap second is skipped and the clock
+is suddenly ahead of UTC by one second. The \fBleapsecmode\fP directive selects how
+that error is corrected. There are four options:
+.sp
+\fBsystem\fP
+.RS 4
+When inserting a leap second, the kernel steps the system clock backwards by
+one second when the clock gets to 00:00:00 UTC. When deleting a leap second, it
+steps forward by one second when the clock gets to 23:59:59 UTC. This is the
+default mode when the system driver supports leap seconds (i.e. all supported
+systems with the exception of macOS 12 and earlier).
+.RE
+.sp
+\fBstep\fP
+.RS 4
+This is similar to the \fBsystem\fP mode, except the clock is stepped by
+\fBchronyd\fP instead of the kernel. It can be useful to avoid bugs in the kernel
+code that would be executed in the \fBsystem\fP mode. This is the default mode
+when the system driver does not support leap seconds.
+.RE
+.sp
+\fBslew\fP
+.RS 4
+The clock is corrected by slewing started at 00:00:00 UTC when a leap second
+is inserted or 23:59:59 UTC when a leap second is deleted. This might be
+preferred over the \fBsystem\fP and \fBstep\fP modes when applications running on the
+system are sensitive to jumps in the system time and it is acceptable that the
+clock will be off for a longer time. On Linux with the default
+\fBmaxslewrate\fP value the correction takes 12 seconds.
+.RE
+.sp
+\fBignore\fP
+.RS 4
+No correction is applied to the clock for the leap second. The clock will be
+corrected later in normal operation when new measurements are made and the
+estimated offset includes the one second error. This option is particularly
+useful when multiple \fBchronyd\fP instances are running on the system, one
+controlling the system clock and others started with the \fB\-x\fP option, which
+should rely on the first instance to correct the system clock and ignore it for
+the correction of their own NTP clock running on top of the system clock.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+When serving time to NTP clients that cannot be configured to correct their
+clocks for a leap second by slewing, or to clients that would correct at
+slightly different rates when it is necessary to keep them close together, the
+\fBslew\fP mode can be combined with the \fBsmoothtime\fP directive to
+enable a server leap smear.
+.sp
+When smearing a leap second, the leap status is suppressed on the server and
+the served time is corrected slowly by slewing instead of stepping. The clients
+do not need any special configuration as they do not know there is any leap
+second and they follow the server time which eventually brings them back to
+UTC. Care must be taken to ensure they use only NTP servers which smear the
+leap second in exactly the same way for synchronisation.
+.sp
+This feature must be used carefully, because the server is intentionally not
+serving its best estimate of the true time.
+.sp
+A recommended configuration to enable a server leap smear is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+leapsecmode slew
+maxslewrate 1000
+smoothtime 400 0.001024 leaponly
+.fam
+.fi
+.if n .RE
+.sp
+The first directive is necessary to disable the clock step which would reset
+the smoothing process. The second directive limits the slewing rate of the
+local clock to 1000 ppm, which improves the stability of the smoothing process
+when the local correction starts and ends. The third directive enables the
+server time smoothing process. It will start when the clock gets to 00:00:00
+UTC and it will take 62500 seconds (about 17.36 hours) to finish. The frequency
+offset will be changing by 0.001024 ppm per second and will reach a maximum of
+32 ppm in 31250 seconds. The \fBleaponly\fP option makes the duration of the leap
+smear constant and allows the clients to safely synchronise with multiple
+identically configured leap smearing servers.
+.sp
+The duration of the leap smear can be calculated from the specified wander as
+.sp
+.if n .RS 4
+.nf
+.fam C
+duration = sqrt(4 / wander)
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBleapsectz\fP \fItimezone\fP
+.RS 4
+This directive specifies a timezone in the system timezone database which
+\fBchronyd\fP can use to determine when will the next leap second occur and what is
+the current offset between TAI and UTC. It will periodically check if 23:59:59
+and 23:59:60 are valid times in the timezone. This normally works with the
+\fIright/UTC\fP timezone.
+.sp
+When a leap second is announced, the timezone needs to be updated at least 12
+hours before the leap second. It is not necessary to restart \fBchronyd\fP.
+.sp
+This directive is useful with reference clocks and other time sources which do
+not announce leap seconds, or announce them too late for an NTP server to
+forward them to its own clients. Clients of leap smearing servers must not
+use this directive.
+.sp
+It is also useful when the system clock is required to have correct TAI\-UTC
+offset. Note that the offset is set only when leap seconds are handled by the
+kernel, i.e. \fBleapsecmode\fP is set to \fBsystem\fP.
+.sp
+The specified timezone is not used as an exclusive source of information about
+leap seconds. If a majority of time sources announce on the last day of June or
+December that a leap second should be inserted or deleted, it will be accepted
+even if it is not included in the timezone.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+leapsectz right/UTC
+.fam
+.fi
+.if n .RE
+.sp
+The following shell command verifies that the timezone contains leap seconds
+and can be used with this directive:
+.sp
+.if n .RS 4
+.nf
+.fam C
+$ TZ=right/UTC date \-d \*(AqDec 31 2008 23:59:60\*(Aq
+Wed Dec 31 23:59:60 UTC 2008
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmakestep\fP \fIthreshold\fP \fIlimit\fP
+.RS 4
+Normally \fBchronyd\fP will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+e.g. when \fBchronyd\fP is initially started, the system clock might be so far
+adrift that this slewing process would take a very long time to correct the
+system clock.
+.sp
+This directive forces \fBchronyd\fP to step the system clock if the adjustment is
+larger than a threshold value, but only if there were no more clock updates
+since \fBchronyd\fP was started than the specified limit. A negative value disables
+the limit.
+.sp
+On most systems it is desirable to step the system clock only on boot, before
+starting programs that rely on time advancing monotonically forwards.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+makestep 0.1 3
+.fam
+.fi
+.if n .RE
+.sp
+This would step the system clock if the adjustment is larger than 0.1 seconds, but
+only in the first three clock updates.
+.RE
+.sp
+\fBmaxchange\fP \fIoffset\fP \fIstart\fP \fIignore\fP
+.RS 4
+This directive sets the maximum offset to be accepted on a clock update. The
+offset is measured relative to the current estimate of the true time, which is
+different from the system time if a previous slew did not finish.
+.sp
+The check is enabled after the specified number of clock updates to allow a
+large initial offset to be corrected on start. Offsets larger than the
+specified maximum will be ignored for the specified number of times. Another
+large offset will cause \fBchronyd\fP to give up and exit. A negative value
+can be used to disable the limit to ignore all large offsets. A syslog message
+will be generated when an offset is ignored or it causes the exit.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+maxchange 1000 1 2
+.fam
+.fi
+.if n .RE
+.sp
+After the first clock update, \fBchronyd\fP will check the offset on every clock
+update, it will ignore two adjustments larger than 1000 seconds and exit on
+another one.
+.RE
+.sp
+\fBmaxclockerror\fP \fIerror\-in\-ppm\fP
+.RS 4
+The \fBmaxclockerror\fP directive sets the maximum assumed frequency error that the
+system clock can gain on its own between clock updates. It describes the
+stability of the clock.
+.sp
+By default, the maximum error is 1 ppm.
+.sp
+Typical values for \fIerror\-in\-ppm\fP might be 10 for a low quality clock and 0.1
+for a high quality clock using a temperature compensated crystal oscillator.
+.RE
+.sp
+\fBmaxdrift\fP \fIdrift\-in\-ppm\fP
+.RS 4
+This directive specifies the maximum assumed drift (frequency error) of the
+system clock. It limits the frequency adjustment that \fBchronyd\fP is allowed to
+use to correct the measured drift. It is an additional limit to the maximum
+adjustment that can be set by the system driver (100000 ppm on Linux, 500 ppm
+on FreeBSD, NetBSD, and macOS 10.13+, 32500 ppm on illumos).
+.sp
+By default, the maximum assumed drift is 500000 ppm, i.e. the adjustment is
+limited by the system driver rather than this directive.
+.RE
+.sp
+\fBmaxupdateskew\fP \fIskew\-in\-ppm\fP
+.RS 4
+One of \fBchronyd\fP\*(Aqs tasks is to work out how fast or slow the computer\(cqs clock
+runs relative to its reference sources. In addition, it computes an estimate of
+the error bounds around the estimated value.
+.sp
+If the range of error is too large, it probably indicates that the measurements
+have not settled down yet, and that the estimated gain or loss rate is not very
+reliable.
+.sp
+The \fBmaxupdateskew\fP directive sets the threshold for determining whether an
+estimate might be so unreliable that it should not be used. By default, the
+threshold is 1000 ppm.
+.sp
+Typical values for \fIskew\-in\-ppm\fP might be 100 for NTP sources polled over a
+wireless network, and 10 or smaller for sources on a local wired network.
+.sp
+It should be noted that this is not the only means of protection against using
+unreliable estimates. At all times, \fBchronyd\fP keeps track of both the estimated
+gain or loss rate, and the error bound on the estimate. When a new estimate is
+generated following another measurement from one of the sources, a weighted
+combination algorithm is used to update the existing estimate. If it has
+significantly smaller error bounds than the new estimate, the existing estimate
+will dominate in the new combined value.
+.RE
+.sp
+\fBmaxslewrate\fP \fIrate\-in\-ppm\fP
+.RS 4
+The \fBmaxslewrate\fP directive sets the maximum rate at which \fBchronyd\fP is allowed
+to slew the time. It limits the slew rate controlled by the correction time
+ratio (which can be set by the \fBcorrtimeratio\fP directive) and
+is effective only on systems where \fBchronyd\fP is able to control the rate (i.e.
+all supported systems with the exception of macOS 12 or earlier).
+.sp
+For each system there is a maximum frequency offset of the clock that can be set
+by the driver. On Linux it is 100000 ppm, on FreeBSD, NetBSD and macOS 10.13+ it
+is 5000 ppm, and on illumos it is 32500 ppm. Also, due to a kernel limitation,
+setting \fBmaxslewrate\fP on FreeBSD, NetBSD, macOS 10.13+ to a value between 500
+ppm and 5000 ppm will effectively set it to 500 ppm.
+.sp
+By default, the maximum slew rate is set to 83333.333 ppm (one twelfth).
+.RE
+.sp
+\fBtempcomp\fP \fIfile\fP \fIinterval\fP \fIT0\fP \fIk0\fP \fIk1\fP \fIk2\fP, \fBtempcomp\fP \fIfile\fP \fIinterval\fP \fIpoints\-file\fP
+.RS 4
+Normally, changes in the rate of drift of the system clock are caused mainly by
+changes in the temperature of the crystal oscillator on the motherboard.
+.sp
+If there are temperature measurements available from a sensor close to the
+oscillator, the \fBtempcomp\fP directive can be used to compensate for the changes
+in the temperature and improve the stability and accuracy of the clock.
+.sp
+The result depends on many factors, including the resolution of the sensor, the
+amount of noise in the measurements, the polling interval of the time source,
+the compensation update interval, how well the compensation is specified, and
+how close the sensor is to the oscillator. When it is working well, the
+frequency reported in the \fItracking.log\fP file is more stable and the maximum
+reached offset is smaller.
+.sp
+There are two forms of the directive. The first one has six parameters: a path
+to the file containing the current temperature from the sensor (in text
+format), the compensation update interval (in seconds), and temperature
+coefficients \fIT0\fP, \fIk0\fP, \fIk1\fP, \fIk2\fP.
+.sp
+The frequency compensation is calculated (in ppm) as
+.sp
+.if n .RS 4
+.nf
+.fam C
+comp = k0 + (T \- T0) * k1 + (T \- T0)^2 * k2
+.fam
+.fi
+.if n .RE
+.sp
+The result has to be between \-10 ppm and 10 ppm, otherwise the measurement is
+considered invalid and will be ignored. The \fIk0\fP coefficient can be adjusted to
+keep the compensation in that range.
+.sp
+An example of the use is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 26000 0.0 0.000183 0.0
+.fam
+.fi
+.if n .RE
+.sp
+The measured temperature will be read from the file in the Linux sysfs
+filesystem every 30 seconds. When the temperature is 26000 (26 degrees
+Celsius), the frequency correction will be zero. When it is 27000 (27 degrees
+Celsius), the clock will be set to run faster by 0.183 ppm, etc.
+.sp
+The second form has three parameters: the path to the sensor file, the update
+interval, and a path to a file containing a list of (temperature, compensation)
+points, from which the compensation is linearly interpolated or extrapolated.
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+tempcomp /sys/class/hwmon/hwmon0/temp2_input 30 /etc/chrony.tempcomp
+.fam
+.fi
+.if n .RE
+.sp
+where the \fI/etc/chrony.tempcomp\fP file could have
+.sp
+.if n .RS 4
+.nf
+.fam C
+20000 1.0
+21000 0.64
+22000 0.36
+23000 0.16
+24000 0.04
+25000 0.0
+26000 0.04
+27000 0.16
+28000 0.36
+29000 0.64
+30000 1.0
+.fam
+.fi
+.if n .RE
+.sp
+Valid measurements with corresponding compensations are logged to the
+\fItempcomp.log\fP file if enabled by the \fBlog tempcomp\fP directive.
+.RE
+.SS "NTP server"
+.sp
+\fBallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The \fBallow\fP directive is used to designate a particular subnet from which NTP
+clients are allowed to access the computer as an NTP server. It also controls
+access of NTS\-KE clients when NTS is enabled on the server.
+.sp
+The default is that no clients are allowed access, i.e. \fBchronyd\fP operates
+purely as an NTP client. If the \fBallow\fP directive is used, \fBchronyd\fP will be
+both a client of its servers, and a server to other clients.
+.sp
+This directive can be used multiple times.
+.sp
+Examples of the use of the directive are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+allow 3.4.5.0/24
+allow 3.4.5
+allow 2001:db8::/32
+allow 0/0
+allow ::/0
+allow
+.fam
+.fi
+.if n .RE
+.sp
+The first directive allows access from an IPv4 address. The second directive
+allows access from all computers in an IPv4 subnet specified in the CIDR
+notation. The third directive specifies the same subnet using a simpler
+notation where the prefix length is determined by the number of dots. The
+fourth directive specifies an IPv6 subnet. The fifth and sixth directives allow
+access from all IPv4 and IPv6 addresses respectively. The seventh directive
+allows access from all addresses (both IPv4 or IPv6).
+.sp
+A second form of the directive, \fBallow all\fP, has a greater effect, depending on
+the ordering of directives in the configuration file. To illustrate the effect,
+consider the two examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow 1.2.0.0/16
+.fam
+.fi
+.if n .RE
+.sp
+and
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+deny 1.2.3.0/24
+allow all 1.2.0.0/16
+.fam
+.fi
+.if n .RE
+.sp
+In the first example, the effect is the same regardless of what order the three
+directives are given in. So the \fI1.2.0.0/16\fP subnet is allowed access, except
+for the \fI1.2.3.0/24\fP subnet, which is denied access, however the host \fI1.2.3.4\fP
+is allowed access.
+.sp
+In the second example, the \fBallow all 1.2.0.0/16\fP directive overrides the
+effect of \fIany\fP previous directive relating to a subnet within the specified
+subnet. Within a configuration file this capability is probably rather moot;
+however, it is of greater use for reconfiguration at run\-time via \fBchronyc\fP
+with the \fBallow all\fP command.
+.sp
+The rules are internally represented as a tree of tables with one level per
+four bits of the IPv4 or IPv6 address. The order of the \fBallow\fP and \fBdeny\fP
+directives matters if they modify the same records of one table, i.e. if one
+subnet is included in the other subnet and their prefix lengths are at the same
+level. For example, \fI1.2.3.0/28\fP and \fI1.2.3.0/29\fP are in different tables, but
+\fI1.2.3.0/25\fP and \fI1.2.3.0/28\fP are in the same table. The configuration can be
+verified for individual addresses with the \fBaccheck\fP
+command in \fBchronyc\fP.
+.sp
+A hostname can be specified in the directives instead of the IP address, but
+the name must be resolvable when \fBchronyd\fP is started, i.e. the network is
+already up and DNS is working. If the hostname resolves to multiple addresses,
+only the first address (in the order returned by the system resolver) will be
+allowed or denied.
+.sp
+Note, if the \fBinitstepslew\fP directive is used in the
+configuration file, each of the computers listed in that directive must allow
+client access by this computer for it to work.
+.RE
+.sp
+\fBdeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP directive, except that it denies NTP
+and NTS\-KE client access to a particular subnet or host, rather than allowing
+it.
+.sp
+The syntax is identical and the directive can be used multiple times too.
+.sp
+There is also a \fBdeny all\fP directive with similar behaviour to the \fBallow all\fP
+directive.
+.RE
+.sp
+\fBbindaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindaddress\fP directive binds the sockets on which \fBchronyd\fP listens for
+NTP and NTS\-KE requests to a local address of the computer. On systems other
+than Linux, the address of the computer needs to be already configured when
+\fBchronyd\fP is started.
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindaddress 192.168.1.1
+.fam
+.fi
+.if n .RE
+.sp
+Currently, for each of the IPv4 and IPv6 protocols, only one \fBbindaddress\fP
+directive can be specified. Therefore, it is not useful on computers which
+should serve NTP on multiple network interfaces.
+.RE
+.sp
+\fBbinddevice\fP \fIinterface\fP
+.RS 4
+The \fBbinddevice\fP directive binds the NTP and NTS\-KE server sockets to a network
+device specified by the interface name. This directive can specify only one
+interface and it is supported on Linux only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+binddevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBbroadcast\fP \fIinterval\fP \fIaddress\fP [\fIport\fP]
+.RS 4
+The \fBbroadcast\fP directive is used to declare a broadcast address to which
+chronyd should send packets in the NTP broadcast mode (i.e. make \fBchronyd\fP act
+as a broadcast server). Broadcast clients on that subnet will be able to
+synchronise.
+.sp
+This directive can be used multiple times to specify multiple addresses.
+.sp
+The syntax is as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+broadcast 32 192.168.1.255
+broadcast 64 192.168.2.255 12123
+broadcast 64 ff02::101
+.fam
+.fi
+.if n .RE
+.sp
+In the first example, the destination port defaults to UDP port 123 (the normal NTP
+port). In the second example, the destination port is specified as 12123. The
+first parameter in each case (32 or 64 respectively) is the interval in seconds
+between broadcast packets being sent. The second parameter in each case is the
+broadcast address to send the packet to. This should correspond to the
+broadcast address of one of the network interfaces on the computer where
+\fBchronyd\fP is running.
+.sp
+You can have more than 1 \fBbroadcast\fP directive if you have more than 1 network
+interface onto which you want to send NTP broadcast packets.
+.sp
+\fBchronyd\fP itself cannot act as a broadcast client; it must always be configured
+as a point\-to\-point client by defining specific NTP servers and peers. This
+broadcast server feature is intended for providing a time source to other NTP
+implementations.
+.sp
+If \fBntpd\fP is used as the broadcast client, it will try to measure the
+round\-trip delay between the server and client with normal client mode packets.
+Thus, the broadcast subnet should also be the subject of an \fBallow\fP
+directive.
+.RE
+.sp
+\fBclientloglimit\fP \fIlimit\fP
+.RS 4
+This directive specifies the maximum amount of memory that \fBchronyd\fP is allowed
+to allocate for logging of client accesses and the state that \fBchronyd\fP as an
+NTP server needs to support the interleaved mode for its clients. The default
+limit is 524288 bytes, which enables monitoring of up to 4096 IP addresses at
+the same time and holding NTP timestamps for up to 4096 clients using the
+interleaved mode (depending on uniformity of their polling interval). The
+number of addresses and timestamps is always a power of 2. The maximum
+effective value is 2147483648 (2 GB), which corresponds to 16777216 addresses
+and timestamps.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clientloglimit 1048576
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBnoclientlog\fP
+.RS 4
+This directive, which takes no arguments, specifies that client accesses are
+not to be logged. Normally they are logged, allowing statistics to be reported
+using the \fBclients\fP command in \fBchronyc\fP. This option
+also effectively disables server support for the NTP interleaved mode.
+.RE
+.sp
+\fBlocal\fP [\fIoption\fP]...
+.RS 4
+The \fBlocal\fP directive enables a local reference mode, which allows \fBchronyd\fP
+operating as an NTP server to appear synchronised to real time (from the
+viewpoint of clients polling it), even when it was never synchronised or
+the last update of the clock happened a long time ago.
+.sp
+This directive is normally used in an isolated network, where computers are
+required to be synchronised to one another, but not necessarily to real time.
+The server can be kept vaguely in line with real time by manual input.
+.sp
+The \fBlocal\fP directive has the following options:
+.sp
+\fBstratum\fP \fIstratum\fP
+.RS 4
+This option sets the stratum of the server which will be reported to clients
+when the local reference is active. The specified value is in the range 1
+through 15, and the default value is 10. It should be larger than the maximum
+expected stratum in the network when external NTP servers are accessible.
+.sp
+Stratum 1 indicates a computer that has a true real\-time reference directly
+connected to it (e.g. GPS, atomic clock, etc.), such computers are expected to
+be very close to real time. Stratum 2 computers are those which have a stratum
+1 server; stratum 3 computers have a stratum 2 server and so on. A value
+of 10 indicates that the clock is so many hops away from a reference clock that
+its time is fairly unreliable.
+.RE
+.sp
+\fBdistance\fP \fIdistance\fP
+.RS 4
+This option sets the threshold for the root distance which will activate the local
+reference. If \fBchronyd\fP was synchronised to some source, the local reference
+will not be activated until its root distance reaches the specified value (the
+rate at which the distance is increasing depends on how well the clock was
+tracking the source). The default value is 1 second.
+.sp
+The current root distance can be calculated from root delay and root dispersion
+(reported by the \fBtracking\fP command in \fBchronyc\fP) as:
+.sp
+.if n .RS 4
+.nf
+.fam C
+distance = delay / 2 + dispersion
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBorphan\fP
+.RS 4
+This option enables a special \(oqorphan\(cq mode, where sources with stratum equal
+to the local \fIstratum\fP are assumed to not serve real time. They are ignored
+unless no other source is selectable and their reference IDs are smaller than
+the local reference ID.
+.sp
+This allows multiple servers in the network to use the same \fBlocal\fP
+configuration and to be synchronised to one another, without confusing clients
+that poll more than one server. Each server needs to be configured to poll all
+other servers with the \fBlocal\fP directive. This ensures only the server with the
+smallest reference ID has the local reference active and others are
+synchronised to it. If that server stops responding, the server with the second
+smallest reference ID will take over when its local reference mode activates
+(root distance reaches the threshold configured by the \fBdistance\fP option).
+.sp
+The \fBorphan\fP mode is compatible with the \fBntpd\fP\*(Aqs orphan mode (enabled by the
+\fBtos orphan\fP command).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+local stratum 10 orphan distance 0.1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBntpsigndsocket\fP \fIdirectory\fP
+.RS 4
+This directive specifies the location of the Samba \fBntp_signd\fP socket when it
+is running as a Domain Controller (DC). If \fBchronyd\fP is compiled with this
+feature, responses to MS\-SNTP clients will be signed by the \fBsmbd\fP daemon.
+.sp
+Note that MS\-SNTP requests are not authenticated and any client that is allowed
+to access the server by the \fBallow\fP directive, or the
+\fBallow\fP command in \fBchronyc\fP, can get an MS\-SNTP
+response signed with a trust account\(cqs password and try to crack the password
+in a brute\-force attack. Access to the server should be carefully controlled.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntpsigndsocket /var/lib/samba/ntp_signd
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBntsport\fP \fIport\fP
+.RS 4
+This directive specifies the TCP port on which \fBchronyd\fP will provide the NTS
+Key Establishment (NTS\-KE) service. The default port is 4460.
+.sp
+The port will be open only when a certificate and key is specified by the
+\fBntsservercert\fP and \fBntsserverkey\fP directives.
+.RE
+.sp
+\fBntsservercert\fP \fIfile\fP
+.RS 4
+This directive specifies a file containing a certificate in the PEM format
+for \fBchronyd\fP to operate as an NTS server. The file should also include
+any intermediate certificates that the clients will need to validate the
+server\(cqs certificate. The file needs to be readable by the user under which
+\fBchronyd\fP is running after dropping root privileges.
+.sp
+This directive can be used multiple times to specify multiple certificates for
+different names of the server.
+.sp
+The files are loaded only once. \fBchronyd\fP needs to be restarted in order to
+load a renewed certificate. The \fBntsdumpdir\fP and
+\fBdumpdir\fP directives with the \fB\-r\fP option of \fBchronyd\fP are
+recommended for a near\-seamless server operation.
+.RE
+.sp
+\fBntsserverkey\fP \fIfile\fP
+.RS 4
+This directive specifies a file containing a private key in the PEM format
+for \fBchronyd\fP to operate as an NTS server. The file needs to be readable by
+the user under which \fBchronyd\fP is running after dropping root privileges. For
+security reasons, it should not be readable by other users.
+.sp
+This directive can be used multiple times to specify multiple keys. The number
+of keys must be the same as the number of certificates and the corresponding
+files must be specified in the same order.
+.RE
+.sp
+\fBntsprocesses\fP \fIprocesses\fP
+.RS 4
+This directive specifies how many helper processes will \fBchronyd\fP operating
+as an NTS server start for handling client NTS\-KE requests in order to improve
+performance with multi\-core CPUs and multithreading. If set to 0, no helper
+process will be started and all NTS\-KE requests will be handled by the main
+\fBchronyd\fP process. The default value is 1.
+.RE
+.sp
+\fBmaxntsconnections\fP \fIconnections\fP
+.RS 4
+This directive specifies the maximum number of concurrent NTS\-KE connections
+per process that the NTS server will accept. The default value is 100. The
+maximum practical value is half of the system \fBFD_SETSIZE\fP constant (usually
+1024).
+.RE
+.sp
+\fBntsdumpdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies a directory where \fBchronyd\fP operating as an NTS server
+can save the keys which encrypt NTS cookies provided to clients. The keys are
+saved to a single file named \fIntskeys\fP. When \fBchronyd\fP is restarted, reloading
+the keys allows the clients to continue using old cookies and avoids a storm of
+NTS\-KE requests. By default, the server does not save the keys.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsdumpdir @CHRONYVARDIR@
+.fam
+.fi
+.if n .RE
+.sp
+This directory is used also by the NTS client to save NTS cookies.
+.RE
+.sp
+\fBntsntpserver\fP \fIhostname\fP
+.RS 4
+This directive specifies the hostname (as a fully qualified domain name) or
+address of the NTP server(s) which is
+provided in the NTS\-KE response to the clients. It allows the NTS\-KE server to
+be separated from the NTP server. However, the servers need to share the keys,
+i.e. external key management needs to be enabled by setting
+\fBntsrotate\fP to 0. By default, no hostname or address is provided
+to the clients, which means they should use the same server for NTS\-KE and NTP.
+.RE
+.sp
+\fBntsrotate\fP \fIinterval\fP
+.RS 4
+This directive specifies the rotation interval (in seconds) of the server key
+which encrypts the NTS cookies. New keys are generated automatically from the
+\fI/dev/urandom\fP device. The server keeps two previous keys to give the clients
+time to get new cookies encrypted by the latest key. The interval is measured
+as the server\(cqs operating time, i.e. the actual interval can be longer if
+\fBchronyd\fP is not running continuously. The default interval is 604800 seconds
+(1 week). The maximum value is 2^31\-1 (68 years).
+.sp
+The automatic rotation of the keys can be disabled by setting \fBntsrotate\fP to 0.
+In this case the keys are assumed to be managed externally. \fBchronyd\fP will not
+save the keys to the \fIntskeys\fP file and will reload the keys from the file when
+the \fBrekey\fP command is issued in \fBchronyc\fP. The file can
+be periodically copied from another server running \fBchronyd\fP (which does
+not have \fBntsrotate\fP set to 0) in order to have one or more servers dedicated
+to NTS\-KE. The file includes the subsequent key to which the NTS\-KE server will
+switch on the next rotation, i.e. the process copying and reloading the file
+does not need to be timed precisely (it can be delayed by up to one rotation
+interval). The NTS\-KE servers need to be configured with the
+\fBntsntpserver\fP directive to point the clients to the right NTP
+server.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsrotate 2592000
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBport\fP \fIport\fP
+.RS 4
+This option allows you to configure the port on which \fBchronyd\fP will listen for
+NTP requests. The port will be open only when an address is allowed by the
+\fBallow\fP directive or the \fBallow\fP command in
+\fBchronyc\fP, an NTP peer is configured, or the broadcast server mode is enabled.
+.sp
+The default value is 123, the standard NTP port. If set to 0, \fBchronyd\fP will
+never open the server port and will operate strictly in a client\-only mode. The
+source port used in NTP client requests can be set by the
+\fBacquisitionport\fP directive.
+.RE
+.sp
+\fBratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables response rate limiting for NTP packets. Its purpose is
+to reduce network traffic with misconfigured or broken NTP clients that are
+polling the server too frequently. The limits are applied to individual IP
+addresses. If multiple clients share one IP address (e.g. multiple hosts behind
+NAT), the sum of their traffic will be limited. If a client that increases its
+polling rate when it does not receive a reply is detected, its rate limiting
+will be temporarily suspended to avoid increasing the overall amount of
+traffic. The maximum number of IP addresses which can be monitored at the same
+time depends on the memory limit set by the \fBclientloglimit\fP
+directive.
+.sp
+The \fBratelimit\fP directive supports a number of options (which can be defined
+in any order):
+.sp
+\fBinterval\fP \fIinterval\fP
+.RS 4
+This option sets the minimum interval between responses. It is defined as a
+power of 2 in seconds. The default value is 3 (8 seconds). The minimum value
+is \-19 (524288 packets per second) and the maximum value is 12 (one packet per
+4096 seconds). Note that with values below \-4 the rate limiting is coarse
+(responses are allowed in bursts, even if the interval between them is shorter
+than the specified interval).
+.RE
+.sp
+\fBburst\fP \fIresponses\fP
+.RS 4
+This option sets the maximum number of responses that can be sent in a burst,
+temporarily exceeding the limit specified by the \fBinterval\fP option. This is
+useful for clients that make rapid measurements on start (e.g. \fBchronyd\fP with
+the \fBiburst\fP option). The default value is 8. The minimum value is 1 and the
+maximum value is 255.
+.RE
+.sp
+\fBleak\fP \fIrate\fP
+.RS 4
+This option sets the rate at which responses are randomly allowed even if the
+limits specified by the \fBinterval\fP and \fBburst\fP options are exceeded. This is
+necessary to prevent an attacker who is sending requests with a spoofed
+source address from completely blocking responses to that address. The leak
+rate is defined as a power of 1/2 and it is 2 by default, i.e. on average at
+least every fourth request has a response. The minimum value is 1 and the
+maximum value is 4.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+An example use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ratelimit interval 1 burst 16
+.fam
+.fi
+.if n .RE
+.sp
+This would reduce the response rate for IP addresses sending packets on average
+more than once per 2 seconds, or sending packets in bursts of more than 16
+packets, by up to 75% (with default \fBleak\fP of 2).
+.RE
+.sp
+\fBntsratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables rate limiting of NTS\-KE requests. It is similar to the
+\fBratelimit\fP directive, except the default interval is 6
+(1 connection per 64 seconds).
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+ntsratelimit interval 3 burst 1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsmoothtime\fP \fImax\-freq\fP \fImax\-wander\fP [\fBleaponly\fP]
+.RS 4
+The \fBsmoothtime\fP directive can be used to enable smoothing of the time that
+\fBchronyd\fP serves to its clients to make it easier for them to track it and keep
+their clocks close together even when large offset or frequency corrections are
+applied to the server\(cqs clock, for example after being offline for a longer
+time.
+.sp
+BE WARNED: The server is intentionally not serving its best estimate of the
+true time. If a large offset has been accumulated, it can take a very long time
+to smooth it out. This directive should be used only when the clients are not
+configured to also poll another NTP server, because they could reject this
+server as a falseticker or fail to select a source completely.
+.sp
+The smoothing process is implemented with a quadratic spline function with two
+or three pieces. It is independent from any slewing applied to the local system
+clock, but the accumulated offset and frequency will be reset when the clock is
+corrected by stepping, e.g. by the \fBmakestep\fP directive or the
+\fBmakestep\fP command in \fBchronyc\fP. The process can be
+reset without stepping the clock by the \fBsmoothtime
+reset\fP command.
+.sp
+The first two arguments of the directive are the maximum frequency offset of
+the smoothed time to the tracked NTP time (in ppm) and the maximum rate at
+which the frequency offset is allowed to change (in ppm per second). \fBleaponly\fP
+is an optional third argument which enables a mode where only leap seconds are
+smoothed out and normal offset and frequency changes are ignored. The \fBleaponly\fP
+option is useful in a combination with the \fBleapsecmode slew\fP
+directive to allow the clients to use multiple time smoothing servers safely.
+.sp
+The smoothing process is activated automatically when 1/10000 of the estimated
+skew of the local clock falls below the maximum rate of frequency change. It
+can be also activated manually by the \fBsmoothtime
+activate\fP command, which is particularly useful when the clock is
+synchronised only with manual input and the skew is always larger than the
+threshold. The \fBsmoothing\fP command can be used to
+monitor the process.
+.sp
+An example suitable for clients using \fBntpd\fP and 1024 second polling interval
+could be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+smoothtime 400 0.001
+.fam
+.fi
+.if n .RE
+.sp
+An example suitable for clients using \fBchronyd\fP on Linux could be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+smoothtime 50000 0.01
+.fam
+.fi
+.if n .RE
+.RE
+.SS "Command and monitoring access"
+.sp
+\fBbindcmdaddress\fP \fIaddress\fP
+.RS 4
+The \fBbindcmdaddress\fP directive specifies a local IP address to which \fBchronyd\fP
+will bind the UDP socket listening for monitoring command packets (issued
+by \fBchronyc\fP). On systems other than Linux, the address of the interface needs
+to be already configured when \fBchronyd\fP is started.
+.sp
+This directive can also change the path of the Unix domain command socket,
+which is used by \fBchronyc\fP to send configuration commands. The socket must be
+in a directory that is accessible only by the root or \fIchrony\fP user. The
+directory will be created on start if it does not exist. The compiled\-in default
+path of the socket is \fI@CHRONYRUNDIR@/chronyd.sock\fP. The socket can be
+disabled by setting the path to \fI/\fP.
+.sp
+By default, \fBchronyd\fP binds the UDP sockets to the addresses \fI127.0.0.1\fP and
+\fI::1\fP (i.e. the loopback interface). This blocks all access except from
+localhost. To listen for command packets on all interfaces, you can add the
+lines:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmdaddress 0.0.0.0
+bindcmdaddress ::
+.fam
+.fi
+.if n .RE
+.sp
+to the configuration file.
+.sp
+For each of the IPv4, IPv6, and Unix domain protocols, only one
+\fBbindcmdaddress\fP directive can be specified.
+.sp
+An example that sets the path of the Unix domain command socket is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmdaddress /var/run/chrony/chronyd.sock
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBbindcmddevice\fP \fIinterface\fP
+.RS 4
+The \fBbindcmddevice\fP directive binds the UDP command sockets to a network device
+specified by the interface name. This directive can specify only one interface
+and it is supported on Linux only.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+bindcmddevice eth0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcmdallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP directive, except that it allows
+monitoring access (rather than NTP client access) to a particular subnet or
+host. (By \(oqmonitoring access\(cq is meant that \fBchronyc\fP can be run on those
+hosts and retrieve monitoring data from \fBchronyd\fP on this computer.)
+.sp
+The syntax is identical to the \fBallow\fP directive.
+.sp
+There is also a \fBcmdallow all\fP directive with similar behaviour to the \fBallow
+all\fP directive (but applying to monitoring access in this case, of course).
+.sp
+Note that \fBchronyd\fP has to be configured with the
+\fBbindcmdaddress\fP directive to not listen only on the
+loopback interface to actually allow remote access.
+.RE
+.sp
+\fBcmddeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBcmdallow\fP directive, except that it denies
+monitoring access to a particular subnet or host, rather than allowing it.
+.sp
+The syntax is identical.
+.sp
+There is also a \fBcmddeny all\fP directive with similar behaviour to the \fBcmdallow
+all\fP directive.
+.RE
+.sp
+\fBcmdport\fP \fIport\fP
+.RS 4
+The \fBcmdport\fP directive allows the port that is used for run\-time monitoring
+(via the \fBchronyc\fP program) to be altered from its default (323). If set to 0,
+\fBchronyd\fP will not open the port, this is useful to disable \fBchronyc\fP
+access from the Internet. (It does not disable the Unix domain command socket.)
+.sp
+An example shows the syntax:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdport 257
+.fam
+.fi
+.if n .RE
+.sp
+This would make \fBchronyd\fP use UDP 257 as its command port. (\fBchronyc\fP would
+need to be run with the \fB\-p 257\fP switch to inter\-operate correctly.)
+.RE
+.sp
+\fBcmdratelimit\fP [\fIoption\fP]...
+.RS 4
+This directive enables response rate limiting for command packets. It is
+similar to the \fBratelimit\fP directive, except responses to
+localhost are never limited and the default interval is \-4 (16 packets per
+second).
+.sp
+An example of the use of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdratelimit interval 2
+.fam
+.fi
+.if n .RE
+.RE
+.SS "Real\-time clock (RTC)"
+.sp
+\fBhwclockfile\fP \fIfile\fP
+.RS 4
+The \fBhwclockfile\fP directive sets the location of the adjtime file which is
+used by the \fBhwclock\fP program on Linux. \fBchronyd\fP parses the file to find out
+if the RTC keeps local time or UTC. It overrides the \fBrtconutc\fP
+directive.
+.sp
+The compiled\-in default value is \*(Aq\fI@DEFAULT_HWCLOCK_FILE@\fP\*(Aq.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+hwclockfile /etc/adjtime
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBrtcautotrim\fP \fIthreshold\fP
+.RS 4
+The \fBrtcautotrim\fP directive is used to keep the RTC close to the system clock
+automatically. When the system clock is synchronised and the estimated error
+between the two clocks is larger than the specified threshold, \fBchronyd\fP will
+trim the RTC as if the \fBtrimrtc\fP command in \fBchronyc\fP
+was issued. The trimming operation is accurate to only about 1 second, which is
+the minimum effective threshold.
+.sp
+This directive is effective only with the \fBrtcfile\fP directive.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+rtcautotrim 30
+.fam
+.fi
+.if n .RE
+.sp
+This would set the threshold error to 30 seconds.
+.RE
+.sp
+\fBrtcdevice\fP \fIdevice\fP
+.RS 4
+The \fBrtcdevice\fP directive sets the path to the device file for accessing the
+RTC. The default path is \fI@DEFAULT_RTC_DEVICE@\fP.
+.RE
+.sp
+\fBrtcfile\fP \fIfile\fP
+.RS 4
+The \fBrtcfile\fP directive defines the name of the file in which \fBchronyd\fP can
+save parameters associated with tracking the accuracy of the RTC.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+rtcfile @CHRONYVARDIR@/rtc
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP saves information in this file when it exits and when the \fBwritertc\fP
+command is issued in \fBchronyc\fP. The information saved is the RTC\(cqs error at
+some epoch, that epoch (in seconds since January 1 1970), and the rate at which
+the RTC gains or loses time.
+.sp
+So far, the support for real\-time clocks is limited; their code is even more
+system\-specific than the rest of the software. You can only use the RTC
+facilities (the \fBrtcfile\fP directive and the \fB\-s\fP command\-line
+option to \fBchronyd\fP) if the following three conditions apply:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+You are running Linux.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The kernel is compiled with extended real\-time clock support (i.e. the
+\fI/dev/rtc\fP device is capable of doing useful things).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+You do not have other applications that need to make use of \fI/dev/rtc\fP at all.
+.RE
+.RE
+.sp
+\fBrtconutc\fP
+.RS 4
+\fBchronyd\fP assumes by default that the RTC keeps local time (including any
+daylight saving changes). This is convenient on PCs running Linux which are
+dual\-booted with Windows.
+.sp
+If you keep the RTC on local time and your computer is off when daylight saving
+(summer time) starts or ends, the computer\(cqs system time will be one hour in
+error when you next boot and start chronyd.
+.sp
+An alternative is for the RTC to keep Universal Coordinated Time (UTC). This
+does not suffer from the 1 hour problem when daylight saving starts or ends.
+.sp
+If the \fBrtconutc\fP directive appears, it means the RTC is required to keep UTC.
+The directive takes no arguments. It is equivalent to specifying the \fB\-u\fP
+switch to the Linux \fBhwclock\fP program.
+.sp
+Note that this setting is overridden by the \fBhwclockfile\fP file
+and is not relevant for the \fBrtcsync\fP directive.
+.RE
+.sp
+\fBrtcsync\fP
+.RS 4
+The \fBrtcsync\fP directive enables a mode where the system time is periodically
+copied to the RTC and \fBchronyd\fP does not try to track its drift. This directive
+cannot be used with the \fBrtcfile\fP directive.
+.sp
+On Linux, the RTC copy is performed by the kernel every 11 minutes.
+.sp
+On macOS, \fBchronyd\fP will perform the RTC copy every 60 minutes
+when the system clock is in a synchronised state.
+.sp
+On other systems this directive does nothing.
+.RE
+.SS "Logging"
+.sp
+\fBlog\fP [\fIoption\fP]...
+.RS 4
+The \fBlog\fP directive indicates that certain information is to be logged.
+The log files are written to the directory specified by the \fBlogdir\fP
+directive. A banner is periodically written to the files to indicate the
+meanings of the columns.
+.sp
+\fBrawmeasurements\fP
+.RS 4
+This option logs the raw NTP measurements and related information to a file
+called \fImeasurements.log\fP. An entry is made for each packet received from the
+source. This can be useful when debugging a problem. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2016\-11\-09 05:40:50 203.0.113.15    N  2 111 111 1111  10 10 1.0 \(rs
+   \-4.966e\-03  2.296e\-01  1.577e\-05  1.615e\-01  7.446e\-03 CB00717B 4B D K
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-10\-13]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address of server or peer from which measurement came [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of the current
+month has 61 seconds, \fI\-\fP means that the last minute of the month has 59
+seconds, \fI?\fP means the remote computer is not currently synchronised.) [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Stratum of remote computer. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+RFC 5905 tests 1 through 3 (1=pass, 0=fail) [111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+RFC 5905 tests 5 through 7 (1=pass, 0=fail) [111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Results of the \fBmaxdelay\fP, \fBmaxdelayratio\fP, and \fBmaxdelaydevratio\fP (or
+\fBmaxdelayquant\fP) tests, and a test for synchronisation loop (1=pass,
+0=fail). The first test from these four also checks the server precision,
+response time, and whether an interleaved response is acceptable for
+synchronisation. [1111]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Local poll [10]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+Remote poll [10]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+\(oqScore\(cq (an internal score within each polling level used to decide when to
+increase or decrease the polling level. This is adjusted based on number of
+measurements currently being used for the regression algorithm). [1.0]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The estimated local clock error (\fItheta\fP in RFC 5905). Positive indicates
+that the local clock is slow of the remote source. [\-4.966e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The peer delay (\fIdelta\fP in RFC 5905). [2.296e\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 14.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 14." 4.2
+.\}
+The peer dispersion (\fIepsilon\fP in RFC 5905). [1.577e\-05]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 15.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 15." 4.2
+.\}
+The root delay (\fIDELTA\fP in RFC 5905). [1.615e\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 16.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 16." 4.2
+.\}
+The root dispersion (\fIEPSILON\fP in RFC 5905). [7.446e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 17.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 17." 4.2
+.\}
+Reference ID of the server\(cqs source as a hexadecimal number. [CB00717B]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 18.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 18." 4.2
+.\}
+NTP mode of the received packet (\fI1\fP=active peer, \fI2\fP=passive peer,
+\fI4\fP=server, \fIB\fP=basic, \fII\fP=interleaved). [4B]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 19.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 19." 4.2
+.\}
+Source of the local transmit timestamp
+(\fID\fP=daemon, \fIK\fP=kernel, \fIH\fP=hardware). [D]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 20.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 20." 4.2
+.\}
+Source of the local receive timestamp
+(\fID\fP=daemon, \fIK\fP=kernel, \fIH\fP=hardware). [K]
+.RE
+.RE
+.sp
+\fBmeasurements\fP
+.RS 4
+This option is identical to the \fBrawmeasurements\fP option, except it logs only
+valid measurements from synchronised sources, i.e. measurements which passed
+the RFC 5905 tests 1 through 7. This can be useful for producing graphs of the
+source\(cqs performance.
+.RE
+.sp
+\fBstatistics\fP
+.RS 4
+This option logs information about the regression processing to a file called
+\fIstatistics.log\fP. An example line (which actually appears as a single line in
+the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2016\-08\-10 05:40:50 203.0.113.15     6.261e\-03 \-3.247e\-03 \(rs
+     2.220e\-03  1.874e\-06  1.080e\-06 7.8e\-02  16   0   8  0.00
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-07\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address of server or peer from which measurement comes [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The estimated standard deviation of the measurements from the source (in
+seconds). [6.261e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The estimated offset of the source (in seconds, positive means the local
+clock is estimated to be fast, in this case). [\-3.247e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The estimated standard deviation of the offset estimate (in seconds).
+[2.220e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The estimated rate at which the local clock is gaining or losing time
+relative to the source (in seconds per second, positive means the local clock
+is gaining). This is relative to the compensation currently being applied to
+the local clock, \fInot\fP to the local clock without any compensation.
+[1.874e\-06]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The estimated error in the rate value (in seconds per second). [1.080e\-06].
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The ratio of |old_rate \- new_rate| / old_rate_error. Large values
+indicate the statistics are not modelling the source very well. [7.8e\-02]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+The number of measurements currently being used for the regression
+algorithm. [16]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+The new starting index (the oldest sample has index 0; this is the method
+used to prune old samples when it no longer looks like the measurements fit a
+linear model). [0, i.e. no samples discarded this time]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The number of runs. The number of runs of regression residuals with the same
+sign is computed. If this is too small it indicates that the measurements are
+no longer represented well by a linear model and that some older samples need
+to be discarded. The number of runs for the data that is being retained is
+tabulated. Values of approximately half the number of samples are expected.
+[8]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The estimated or configured asymmetry of network jitter on the path to the
+source which was used to correct the measured offsets. The asymmetry can be
+between \-0.5 and +0.5. A negative value means the delay of packets sent to
+the source is more variable than the delay of packets sent from the source
+back. [0.00, i.e. no correction for asymmetry]
+.RE
+.RE
+.sp
+\fBselection\fP
+.RS 4
+This option logs information about selection of sources for synchronisation to
+a file called \fIselection.log\fP. Note that the rate of entries written to this
+file grows quadratically with the number of specified sources (each measurement
+triggers the selection for all sources). An example line (which actually
+appears as a single line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2022\-05\-01 02:01:20 203.0.113.15    * \-\-\-\-\-  377  1.00  \(rs
+     4.228e+01 \-1.575e\-04  1.239e\-04
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2022\-05\-01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [02:01:20]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+IP address or reference ID of the source. [203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+State of the source indicated with one of the following symbols. [*]
+.sp
+
+.RS 4
+Not considered selectable for synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP \- has the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIs\fP \- is not synchronised.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIM\fP \- does not have enough measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fId\fP \- has a root distance larger than the maximum distance (configured by the
+\fBmaxdistance\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP \- has a jitter larger than the maximum jitter (configured by the
+\fBmaxjitter\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIw\fP \- waits for other sources to get out of the \fIM\fP state.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIS\fP \- has older measurements than other sources.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIO\fP \- has a stratum equal or larger than the orphan stratum (configured by
+the \fBlocal\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP \- does not fully agree with sources that have the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP \- does not agree with other sources (falseticker).
+.RE
+.RE
+.sp
+
+.RS 4
+Considered selectable for synchronisation, but not currently used:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIW\fP \- waits for other sources to be selectable (required by the
+\fBminsources\fP directive, or the \fBrequire\fP option of
+another source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP \- another selectable source is preferred due to the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIU\fP \- waits for a new measurement (after selecting a different best source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fID\fP \- has, or recently had, a root distance which is too large to be combined
+with other sources (configured by the \fBcombinelimit\fP
+directive).
+.RE
+.RE
+.sp
+
+.RS 4
+Used for synchronisation of the local clock:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP \- combined with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP \- selected as the best source to update the reference data (e.g. root
+delay, root dispersion).
+.RE
+.RE
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Current effective selection options of the source. which can be different
+from the configured options due to the authentication selection mode
+(configured by the \fBauthselectmode\fP directive). [\-\-\-\-\-]
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP indicates the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP indicates the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP indicates the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIR\fP indicates the \fBrequire\fP option.
+.RE
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Reachability register printed as an octal number. The register has 8 bits and
+is updated on every received or missed packet from the source. A value of 377
+indicates that a valid reply was received for all from the last eight
+transmissions. [377]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+Current score against the source in the \fI*\fP state. The scoring system avoids
+frequent reselection when multiple sources have a similar root distance. A
+value larger than 1 indicates this source was better than the \fI*\fP source in
+recent selections. If the score reaches 10, the best source will be reselected
+and the scores will be reset to 1. [1.00]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Interval since the last measurement of the source in seconds. [4.228e+01]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Lower endpoint of the interval which was expected to contain the true offset
+of the local clock determined by the root distance of the source. [\-1.575e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+Upper endpoint of the interval which was expected to contain the true offset
+of the local clock determined by the root distance of the source. [1.239e\-04]
+.RE
+.RE
+.sp
+\fBtracking\fP
+.RS 4
+This option logs changes to the estimate of the system\(cqs gain or loss rate, and
+any slews made, to a file called \fItracking.log\fP. An example line (which
+actually appears as a single line in the file) from the log file is shown
+below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2017\-08\-22 13:22:36 203.0.113.15     2     \-3.541      0.075 \-8.621e\-06 N \(rs
+            2  2.940e\-03 \-2.084e\-04  1.534e\-02  3.472e\-04  8.304e\-03
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the
+values from the example line above) :
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2017\-08\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [13:22:36]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The IP address of the server or peer to which the local system is synchronised.
+[203.0.113.15]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The stratum of the local system. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The local system frequency (in ppm, positive means the local system runs fast
+of UTC). [\-3.541]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The error bounds on the frequency (in ppm). [0.075]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The estimated local offset at the epoch, which is normally corrected by
+slewing the local clock (in seconds, positive indicates the clock is fast of
+UTC). [\-8.621e\-06]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of this month
+has 61 seconds, \fI\-\fP means that the last minute of the month has 59 seconds,
+\fI?\fP means the clock is not currently synchronised.) [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The number of combined sources. [2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+The estimated standard deviation of the combined offset (in seconds).
+[2.940e\-03]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 11.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 11." 4.2
+.\}
+The remaining offset correction from the previous update (in seconds,
+positive means the system clock is slow of UTC). [\-2.084e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 12.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 12." 4.2
+.\}
+The total of the network path delays to the reference clock to which
+the local clock is ultimately synchronised (in seconds). [1.534e\-02]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 13.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 13." 4.2
+.\}
+The total dispersion accumulated through all the servers back to the
+reference clock to which the local clock is ultimately synchronised
+(in seconds). [3.472e\-04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 14.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 14." 4.2
+.\}
+The maximum estimated error of the system clock in the interval since the
+previous update (in seconds). It includes the offset, remaining offset
+correction, root delay, and dispersion from the previous update with the
+dispersion which accumulated in the interval. [8.304e\-03]
+.RE
+.RE
+.sp
+\fBrtc\fP
+.RS 4
+This option logs information about the system\(cqs real\-time clock. An example
+line (which actually appears as a single line in the file) from the \fIrtc.log\fP
+file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2015\-07\-22 05:40:50     \-0.037360 1       \-0.037434\(rs
+          \-37.948  12   5  120
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the
+values from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-07\-22]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [05:40:50]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The measured offset between the RTC and the system clock in seconds.
+Positive indicates that the RTC is fast of the system time [\-0.037360].
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Flag indicating whether the regression has produced valid coefficients.
+(1 for yes, 0 for no). [1]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Offset at the current time predicted by the regression process. A large
+difference between this value and the measured offset tends to indicate that
+the measurement is an outlier with a serious measurement error. [\-0.037434]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+The rate at which the RTC is losing or gaining time relative to the system
+clock. In ppm, with positive indicating that the RTC is gaining time.
+[\-37.948]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The number of measurements used in the regression. [12]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The number of runs of regression residuals of the same sign. Low values
+indicate that a straight line is no longer a good model of the measured data
+and that older measurements should be discarded. [5]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The measurement interval used prior to the measurement being made (in
+seconds). [120]
+.RE
+.RE
+.sp
+\fBrefclocks\fP
+.RS 4
+This option logs the raw and filtered reference clock measurements to a file
+called \fIrefclocks.log\fP. An example line (which actually appears as a single
+line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2009\-11\-30 14:33:27.000000 PPS2    7 N 1  4.900000e\-07 \-6.741777e\-07  1.000e\-06
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2009\-11\-30]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second.Microsecond. Note that the date\-time pair is expressed in
+UTC, not the local time zone. [14:33:27.000000]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Reference ID of the reference clock from which the measurement came. [PPS2]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Sequence number of driver poll within one polling interval for raw samples,
+or \fI\-\fP for filtered samples. [7]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+Leap status (\fIN\fP means normal, \fI+\fP means that the last minute of the current
+month has 61 seconds, \fI\-\fP means that the last minute of the month has 59
+seconds). [N]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Flag indicating whether the sample comes from PPS source. (1 for yes,
+0 for no, or \fI\-\fP for filtered sample). [1]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+Local clock error measured by reference clock driver, or \fI\-\fP for filtered sample.
+[4.900000e\-07]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+Local clock error with applied corrections. Positive indicates that the local
+clock is slow. [\-6.741777e\-07]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+Assumed dispersion of the sample. [1.000e\-06]
+.RE
+.RE
+.sp
+\fBtempcomp\fP
+.RS 4
+This option logs the temperature measurements and system rate compensations to
+a file called \fItempcomp.log\fP. An example line (which actually appears as a
+single line in the file) from the log file is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+2015\-04\-19 10:39:48  2.8000e+04  3.6600e\-01
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows (the quantities in square brackets are the values
+from the example line above):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Date [2015\-04\-19]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Hour:Minute:Second. Note that the date\-time pair is expressed in UTC, not the
+local time zone. [10:39:48]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Temperature read from the sensor. [2.8000e+04]
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Applied compensation in ppm, positive means the system clock is running
+faster than it would be without the compensation. [3.6600e\-01]
+.RE
+.RE
+.RE
+.sp
+
+.RS 4
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+log measurements statistics tracking
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBlogbanner\fP \fIentries\fP
+.RS 4
+A banner is periodically written to the log files enabled by the \fBlog\fP
+directive to indicate the meanings of the columns.
+.sp
+The \fBlogbanner\fP directive specifies after how many entries in the log file
+should be the banner written. The default is 32, and 0 can be used to disable
+it entirely.
+.RE
+.sp
+\fBlogchange\fP \fIthreshold\fP
+.RS 4
+This directive sets the threshold for the adjustment of the system clock that
+will generate a syslog message. Clock errors detected via NTP packets,
+reference clocks, or timestamps entered via the
+\fBsettime\fP command of \fBchronyc\fP are logged.
+.sp
+By default, the threshold is 1 second.
+.sp
+An example of the use is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+logchange 0.1
+.fam
+.fi
+.if n .RE
+.sp
+which would cause a syslog message to be generated if a system clock error of over
+0.1 seconds starts to be compensated.
+.RE
+.sp
+\fBlogdir\fP \fIdirectory\fP
+.RS 4
+This directive specifies the directory for writing log files enabled by the
+\fBlog\fP directive. If the directory does not exist, it will be created
+automatically.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+logdir /var/log/chrony
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmailonchange\fP \fIemail\fP \fIthreshold\fP
+.RS 4
+This directive defines an email address to which mail should be sent if
+\fBchronyd\fP applies a correction exceeding a particular threshold to the system
+clock.
+.sp
+An example of the use of this directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+mailonchange root@localhost 0.5
+.fam
+.fi
+.if n .RE
+.sp
+This would send a mail message to root if a change of more than 0.5 seconds
+were applied to the system clock.
+.sp
+This directive cannot be used when a system call filter is enabled by the \fB\-F\fP
+option as the \fBchronyd\fP process will not be allowed to fork and execute the
+sendmail binary.
+.RE
+.SS "Miscellaneous"
+.sp
+\fBconfdir\fP \fIdirectory\fP...
+.RS 4
+The \fBconfdir\fP directive includes configuration files with the \fI.conf\fP suffix
+from a directory. The files are included in the lexicographical order of the
+file names.
+.sp
+Multiple directories (up to 10) can be specified with a single \fBconfdir\fP
+directive. In this case, if multiple directories contain a file with the same
+name, only the first file in the order of the specified directories will be
+included. This enables a fragmented configuration where existing fragments can
+be replaced by adding files to a different directory.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+confdir @SYSCONFDIR@/chrony.d
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsourcedir\fP \fIdirectory\fP...
+.RS 4
+The \fBsourcedir\fP directive is identical to the \fBconfdir\fP directive, except the
+configuration files have the \fI.sources\fP suffix, they can only specify NTP
+sources (i.e. the \fBserver\fP, \fBpool\fP, and \fBpeer\fP directives), they are expected
+to have all lines terminated by the newline character, and they can be
+reloaded by the \fBreload sources\fP command in
+\fBchronyc\fP. It is particularly useful with dynamic sources like NTP servers
+received from a DHCP server, which can be written to a file specific to the
+network interface by a networking script.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+sourcedir /var/run/chrony\-dhcp
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBinclude\fP \fIpattern\fP
+.RS 4
+The \fBinclude\fP directive includes a configuration file, or multiple configuration
+files if a wildcard pattern is specified. Unlike with the \fBconfdir\fP directive,
+the full name of the files needs to be specified and at least one file is
+required to exist.
+.sp
+This directive can be used multiple times.
+.sp
+An example of the directive is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+include @SYSCONFDIR@/chrony.d/*.conf
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBhwtimestamp\fP \fIinterface\fP [\fIoption\fP]...
+.RS 4
+This directive enables hardware timestamping of NTP packets sent to and
+received from the specified network interface. The network interface controller
+(NIC) uses its own clock to accurately timestamp the actual transmissions and
+receptions, avoiding processing and queueing delays in the kernel, network
+driver, and hardware. This can significantly improve the accuracy of the
+timestamps and the measured offset, which is used for synchronisation of the
+system clock. In order to get the best results, both sides receiving and
+sending NTP packets (i.e. server and client, or two peers) need to use HW
+timestamping. If the server or peer supports the interleaved mode, it needs to
+be enabled by the \fBxleave\fP option in the \fBserver\fP or the
+\fBpeer\fP directive.
+.sp
+This directive is supported on Linux 3.19 and newer. The NIC must support HW
+timestamping, which can be verified with the \fBethtool \-T\fP command. The list of
+capabilities should include \fIhardware\-raw\-clock\fP, \fIhardware\-transmit\fP, and
+\fIhardware\-receive\fP. The receive filter \fIall\fP, or \fIntp\fP, is necessary for
+timestamping of received NTP packets. Timestamping of packets received on
+bridged and bonded interfaces is supported on Linux 4.13 and newer. If HW
+timestamping does not work for received packets, \fBchronyd\fP will use kernel
+receive timestamps instead. Transmit\-only HW timestamping can still be useful
+to improve stability of the synchronisation.
+.sp
+\fBchronyd\fP does not synchronise the NIC clock. It assumes the clock is running
+free. Multiple instances of \fBchronyd\fP can use the same interface with enabled
+HW timestamping. Applications which need HW timestamping with a synchronised
+clock (e.g. a PTP daemon) should use a virtual clock running on top of the
+physical clock created by writing to \fI/sys/class/ptp/ptpX/n_vclocks\fP. This
+feature is available on Linux 5.14 and newer.
+.sp
+If the kernel supports software timestamping, it will be enabled for all
+interfaces automatically.
+.sp
+The source of timestamps (i.e. hardware, kernel, or daemon) is indicated on the
+client side in the \fImeasurements.log\fP file (if enabled by the \fBlog\fP
+directive) and the \fBntpdata\fP report. On the server
+side, the number of served timestamps from each source is provided in the
+\fBserverstats\fP report.
+.sp
+This directive can be used multiple times to enable HW timestamping on multiple
+interfaces. If the specified interface is \fI*\fP, \fBchronyd\fP will try to enable HW
+timestamping on all available interfaces.
+.sp
+The \fBhwtimestamp\fP directive has the following options:
+.sp
+\fBminpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the minimum interval between readings of the NIC clock.
+It\(cqs defined as a power of 2. It should correspond to the minimum polling
+interval of all NTP sources and the minimum expected polling interval of NTP
+clients. The default value is 0 (1 second), the minimum value is \-6 (1/64th
+of a second), and the maximum value is 20 (about 12 days).
+.RE
+.sp
+\fBmaxpoll\fP \fIpoll\fP
+.RS 4
+This option specifies the maximum interval between readings of the NIC clock,
+as a power of 2. The default value is \fBminpoll\fP + 1, i.e. 1 (2 seconds) with
+the default \fBminpoll\fP of 0. The minimum and maximum values are the same as with
+the \fBminpoll\fP option.
+.RE
+.sp
+\fBminsamples\fP \fIsamples\fP
+.RS 4
+This option specifies the minimum number of readings kept for tracking of the
+NIC clock. The default value is 2.
+.RE
+.sp
+\fBmaxsamples\fP \fIsamples\fP
+.RS 4
+This option specifies the maximum number of readings kept for tracking of the
+NIC clock. The default value is 16.
+.RE
+.sp
+\fBprecision\fP \fIprecision\fP
+.RS 4
+This option specifies the assumed precision of reading of the NIC clock. The
+default value is 100e\-9 (100 nanoseconds).
+.RE
+.sp
+\fBtxcomp\fP \fIcompensation\fP
+.RS 4
+This option specifies the difference in seconds between the actual transmission
+time at the physical layer and the reported transmit timestamp. This value will
+be added to transmit timestamps obtained from the NIC. The default value is 0.
+.RE
+.sp
+\fBrxcomp\fP \fIcompensation\fP
+.RS 4
+This option specifies the difference in seconds between the reported receive
+timestamp and the actual reception time at the physical layer. This value will
+be subtracted from receive timestamps obtained from the NIC. The default value
+is 0.
+.RE
+.sp
+\fBnocrossts\fP
+.RS 4
+Some hardware can precisely cross timestamp the NIC clock with the system
+clock. This option disables the use of the cross timestamping.
+.RE
+.sp
+\fBrxfilter\fP \fIfilter\fP
+.RS 4
+This option selects the receive timestamping filter. The \fIfilter\fP can be one of
+the following:
+.sp
+\fIall\fP
+.RS 4
+Enables timestamping of all received packets.
+.RE
+.sp
+\fIntp\fP
+.RS 4
+Enables timestamping of received NTP packets.
+.RE
+.sp
+\fIptp\fP
+.RS 4
+Enables timestamping of received PTP packets.
+.RE
+.sp
+\fInone\fP
+.RS 4
+Disables timestamping of received packets.
+.RE
+.RE
+.sp
+
+.RS 4
+The most specific filter for timestamping of NTP packets supported by the NIC
+is selected by default. Some NICs can timestamp PTP packets only. By default,
+they will be configured with the \fInone\fP filter and expected to provide hardware
+timestamps for transmitted packets only. Timestamping of PTP packets is useful
+with NTP\-over\-PTP enabled by the \fBptpport\fP
+directive, or when another application is receiving PTP packets on the
+interface. Forcing timestamping of all packets with the \fIall\fP filter could be
+useful if the NIC supported both the \fIall\fP and \fIntp\fP filters, and it should
+timestamp both NTP and PTP packets, or NTP packets on a different UDP port.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+Examples of the directive are:
+.sp
+.if n .RS 4
+.nf
+.fam C
+hwtimestamp eth0
+hwtimestamp eth1 txcomp 300e\-9 rxcomp 645e\-9
+hwtimestamp *
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBhwtstimeout\fP \fItimeout\fP
+.RS 4
+If hardware timestamping is used with a close NTP server, or the NIC or its
+driver is slow in providing the transmit timestamp of NTP requests, a response
+from the server can be received before the transmit timestamp of the request.
+To avoid calculating the offset with a less accurate transmit timestamp,
+\fBchronyd\fP can save the response for later processing and wait for the hardware
+transmit timestamp. There is no guarantee that the timestamp will be provided
+(NICs typically have a limited rate of transmit timestamping). This directive
+configures how long should \fBchronyd\fP wait for the timestamp after receiving a
+valid response from the server. If a second valid response is received from the
+server while waiting for the timestamp, they will be both processed
+immediately.
+.sp
+The default value is 0.001 seconds, which should be sufficient with most
+hardware. If you frequently see kernel transmit timestamps in the
+\fImeasurements.log\fP file or \fBntpdata\fP report, and it is
+not a server handling a high rate of requests in the interleaved mode on the
+same interface (which would compete with timestamping of the server\(cqs own
+requests), increasing the timeout to 0.01 or possibly even longer might help.
+Note that the maximum timeout is limited by the NTP polling interval.
+.RE
+.sp
+\fBkeyfile\fP \fIfile\fP
+.RS 4
+This directive is used to specify the location of the file containing symmetric
+keys which are shared between NTP servers and clients, or peers, in order to
+authenticate NTP packets with a message authentication code (MAC) using a
+cryptographic hash function or cipher.
+.sp
+The format of the directive is shown in the example below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keyfile @SYSCONFDIR@/chrony.keys
+.fam
+.fi
+.if n .RE
+.sp
+The argument is simply the name of the file containing the ID\-key pairs. The
+format of the file is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+10 tulip
+11 hyacinth
+20 MD5 ASCII:crocus
+25 SHA1 HEX:933F62BE1D604E68A81B557F18CFA200483F5B70
+30 AES128 HEX:7EA62AE64D190114D46D5A082F948EC1
+31 AES256 HEX:37DDCBC67BB902BCB8E995977FAB4D2B5642F5B32EBCEEE421921D97E5CBFE39
+ ...
+.fam
+.fi
+.if n .RE
+.sp
+Each line consists of an ID, optional type, and key.
+.sp
+The ID can be any positive integer in the range 1 through 2^32\-1.
+.sp
+The type is a name of a cryptographic hash function or cipher which is used to
+generate and verify the MAC. The default type is \fBMD5\fP, which is always
+supported.
+If \fBchronyd\fP was built with enabled support for hashing using a crypto library
+(Nettle, GnuTLS, NSS, or LibTomCrypt), the following functions are available: \fBMD5\fP,
+\fBSHA1\fP, \fBSHA256\fP, \fBSHA384\fP, \fBSHA512\fP. Depending on which library and version is
+\fBchronyd\fP using, some of the following hash functions and ciphers may
+also be available:
+\fBSHA3\-224\fP, \fBSHA3\-256\fP, \fBSHA3\-384\fP, \fBSHA3\-512\fP, \fBTIGER\fP, \fBWHIRLPOOL\fP, \fBAES128\fP,
+\fBAES256\fP.
+.sp
+The key can be specified as a string of ASCII characters not containing white
+space with an optional \fBASCII:\fP prefix, or as a hexadecimal number with the
+\fBHEX:\fP prefix. The maximum length of the line is 2047 characters.
+If the type is a cipher, the length of the key must match the cipher (i.e. 128
+bits for AES128 and 256 bits for AES256).
+.sp
+It is recommended to use randomly generated keys, specified in the hexadecimal
+format, which are at least 128 bits long (i.e. they have at least 32 characters
+after the \fBHEX:\fP prefix). \fBchronyd\fP will log a warning to syslog on start if a
+source is specified in the configuration file with a key shorter than 80 bits.
+.sp
+The recommended key types are AES ciphers and SHA3 hash functions. MD5 should
+be avoided unless no other type is supported on the server and client, or
+peers.
+.sp
+The \fBkeygen\fP command of \fBchronyc\fP can be used to
+generate random keys for the key file. By default, it generates 160\-bit MD5 or
+SHA1 keys.
+.sp
+For security reasons, the file should be readable only by root and the user
+under which \fBchronyd\fP is normally running (to allow \fBchronyd\fP to re\-read the
+file when the \fBrekey\fP command is issued by \fBchronyc\fP).
+.RE
+.sp
+\fBlock_all\fP
+.RS 4
+The \fBlock_all\fP directive will lock the \fBchronyd\fP process into RAM so that it
+will never be paged out. This can result in lower and more consistent latency.
+The directive is supported on Linux, FreeBSD, NetBSD, and illumos.
+.RE
+.sp
+\fBpidfile\fP \fIfile\fP
+.RS 4
+Unless \fBchronyd\fP is started with the \fB\-Q\fP option, it writes its process ID
+(PID) to a file, and checks this file on startup to see if another \fBchronyd\fP
+might already be running on the system. By default, the file used is
+\fI@DEFAULT_PID_FILE@\fP. The \fBpidfile\fP directive allows the name to be changed,
+e.g.:
+.sp
+.if n .RS 4
+.nf
+.fam C
+pidfile /run/chronyd.pid
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBptpport\fP \fIport\fP
+.RS 4
+The \fBptpport\fP directive enables \fBchronyd\fP to send and receive NTP messages
+contained in PTP event messages (NTP\-over\-PTP) to enable hardware timestamping
+on NICs which cannot timestamp NTP packets, but can timestamp unicast PTP
+packets. The port recognized by the NICs is 319 (PTP event port). The default
+value is 0 (disabled).
+.sp
+The NTP\-over\-PTP support is experimental. The protocol and configuration can
+change in future. It should be used only in local networks and expected to work
+only between servers and clients running the same version of \fBchronyd\fP.
+.sp
+The PTP port will be open even if \fBchronyd\fP is not configured to operate as a
+server or client. The directive does not change the default protocol of
+specified NTP sources. Each NTP source that should use NTP\-over\-PTP needs to
+be specified with the \fBport\fP option set to the PTP port. To actually enable
+hardware timestamping on NICs which can timestamp PTP packets only, the
+\fBrxfilter\fP option of the \fBhwtimestamp\fP directive needs to be set to \fIptp\fP.
+.sp
+An example of client configuration is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net minpoll 0 maxpoll 0 xleave port 319
+hwtimestamp * rxfilter ptp
+ptpport 319
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBsched_priority\fP \fIpriority\fP
+.RS 4
+On Linux, FreeBSD, NetBSD, and illumos, the \fBsched_priority\fP directive will
+select the SCHED_FIFO real\-time scheduler at the specified priority (which must
+be between 0 and 100). On macOS, this option must have either a value of 0 (the
+default) to disable the thread time constraint policy or 1 for the policy to be
+enabled.
+.sp
+On systems other than macOS, this directive uses the \fBpthread_setschedparam()\fP
+system call to instruct the kernel to use the SCHED_FIFO first\-in, first\-out
+real\-time scheduling policy for \fBchronyd\fP with the specified priority. This
+means that whenever \fBchronyd\fP is ready to run it will run, interrupting
+whatever else is running unless it is a higher priority real\-time process. This
+should not impact performance as \fBchronyd\fP resource requirements are modest,
+but it should result in lower and more consistent latency since \fBchronyd\fP will
+not need to wait for the scheduler to get around to running it. You should not
+use this unless you really need it. The \fBpthread_setschedparam(3)\fP man page has
+more details.
+.sp
+On macOS, this directive uses the \fBthread_policy_set()\fP kernel call to
+specify real\-time scheduling. As noted above, you should not use this directive
+unless you really need it.
+.RE
+.sp
+\fBuser\fP \fIuser\fP
+.RS 4
+The \fBuser\fP directive sets the name of the system user to which \fBchronyd\fP will
+switch after start in order to drop root privileges.
+.sp
+On Linux, \fBchronyd\fP needs to be compiled with support for the \fBlibcap\fP library.
+On macOS, FreeBSD, NetBSD and illumos \fBchronyd\fP forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+.sp
+The compiled\-in default value is \fI@DEFAULT_USER@\fP.
+.RE
+.SH "EXAMPLES"
+.SS "NTP client with permanent connection to NTP servers"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that are connected
+to the Internet (or to any network containing true NTP servers which ultimately
+derive their time from a reference clock) permanently or most of the time.
+.sp
+To operate in this mode, you will need to know the names of the NTP servers
+you want to use. You might be able to find names of suitable servers by one of
+the following methods:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Your institution might already operate servers on its network.
+Contact your system administrator to find out.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Your ISP probably has one or more NTP servers available for its
+customers.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Somewhere under the NTP homepage there is a list of public
+stratum 1 and stratum 2 servers. You should find one or more servers that are
+near to you. Check that their access policy allows you to use their
+facilities.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+Use public servers from the \c
+.URL "https://www.pool.ntp.org/" "pool.ntp.org" ""
+project.
+.RE
+.sp
+Assuming that your NTP servers are called \fIfoo.example.net\fP, \fIbar.example.net\fP
+and \fIbaz.example.net\fP, your \fIchrony.conf\fP file could contain as a minimum:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net
+server bar.example.net
+server baz.example.net
+.fam
+.fi
+.if n .RE
+.sp
+However, you will probably want to include some of the other directives. The
+\fBdriftfile\fP, \fBmakestep\fP and \fBrtcsync\fP
+might be particularly useful. Also, the \fBiburst\fP option of the
+\fBserver\fP directive is useful to speed up the initial
+synchronisation. The smallest useful configuration file would look something
+like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+When using a pool of NTP servers (one name is used for multiple servers which
+might change over time), it is better to specify them with the \fBpool\fP
+directive instead of multiple \fBserver\fP directives. The configuration file could
+in this case look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+pool pool.ntp.org iburst
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+If the servers (or pool) support the Network Time Security (NTS)
+authentication mechanism and \fBchronyd\fP is compiled with NTS support, the \fBnts\fP
+option will enable a secure synchronisation to the servers. The configuration
+file could look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst nts
+server bar.example.net iburst nts
+server baz.example.net iburst nts
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.SS "NTP client with infrequent connection to NTP servers"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that have
+occasional connections to NTP servers. In this case, you will need some
+additional configuration to tell \fBchronyd\fP when the connection goes up and
+down. This saves the program from continuously trying to poll the servers when
+they are inaccessible.
+.sp
+Again, assuming that your NTP servers are called \fIfoo.example.net\fP,
+\fIbar.example.net\fP and \fIbaz.example.net\fP, your \fIchrony.conf\fP file would now
+contain:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net offline
+server bar.example.net offline
+server baz.example.net offline
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The \fBoffline\fP keyword indicates that the servers start in an offline state, and
+that they should not be contacted until \fBchronyd\fP receives notification from
+\fBchronyc\fP that the link to the Internet is present. To tell \fBchronyd\fP when to
+start and finish sampling the servers, the \fBonline\fP and
+\fBoffline\fP commands of \fBchronyc\fP need to be used.
+.sp
+To give an example of their use, assuming that \fBpppd\fP is the program being
+used to connect to the Internet and that \fBchronyc\fP has been installed at
+\fI@BINDIR@/chronyc\fP, the script \fI/etc/ppp/ip\-up\fP would include:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc online
+.fam
+.fi
+.if n .RE
+.sp
+and the script \fI/etc/ppp/ip\-down\fP would include:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc offline
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP\*(Aqs polling of the servers would now only occur whilst the machine is
+actually connected to the Internet.
+.SS "Isolated networks"
+.sp
+This section shows how to configure \fBchronyd\fP for computers that never have
+network connectivity to any computer which ultimately derives its time from a
+reference clock.
+.sp
+In this situation, one computer is selected to be the primary timeserver. The
+other computers are either direct clients of the server, or clients of clients.
+.sp
+The \fBlocal\fP directive enables a local reference mode, which allows
+\fBchronyd\fP to appear synchronised even when it is not.
+.sp
+The rate value in the server\(cqs drift file needs to be set to the average rate
+at which the server gains or loses time. \fBchronyd\fP includes support for this,
+in the form of the \fBmanual\fP directive and the
+\fBsettime\fP command in the \fBchronyc\fP program.
+.sp
+If the server is rebooted, \fBchronyd\fP can re\-read the drift rate from the drift
+file. However, the server has no accurate estimate of the current time. To get
+around this, the system can be configured so that the server can initially set
+itself to a \(oqmajority\-vote\(cq of selected clients\*(Aq times; this allows the
+clients to \(oqflywheel\(cq the server while it is rebooting.
+.sp
+The \fBsmoothtime\fP directive is useful when the clocks of the
+clients need to stay close together when the local time is adjusted by the
+\fBsettime\fP command. The smoothing process needs to be
+activated by the \fBsmoothtime activate\fP command when
+the local time is ready to be served. After that point, any adjustments will be
+smoothed out.
+.sp
+A typical configuration file for the server (called \fIntp.local\fP) might be
+(assuming the clients and the server are in the \fI192.168.165.x\fP subnet):
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 1 client1 client3 client6
+driftfile @CHRONYVARDIR@/drift
+local stratum 8
+manual
+allow 192.168.165.0/24
+smoothtime 400 0.01
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+For the clients that have to resynchronise the server when it restarts,
+the configuration file might be:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server ntp.local iburst
+driftfile @CHRONYVARDIR@/drift
+allow 192.168.165.0/24
+makestep 1.0 3
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The rest of the clients would be the same, except that the \fBallow\fP directive is
+not required.
+.sp
+If there is no suitable computer to be designated as the primary server, or
+there is a requirement to keep the clients synchronised even when it fails, the
+\fBorphan\fP option of the \fBlocal\fP directive enables a special mode where the
+server is selected from multiple computers automatically. They all need to use
+the same \fBlocal\fP configuration and poll one another. The server with the
+smallest reference ID (which is based on its IP address) will take the role of
+the primary server and others will be synchronised to it. When it fails, the
+server with the second smallest reference ID will take over and so on.
+.sp
+A configuration file for the first server might be (assuming there are three
+servers called \fIntp1.local\fP, \fIntp2.local\fP, and \fIntp3.local\fP):
+.sp
+.if n .RS 4
+.nf
+.fam C
+initstepslew 1 ntp2.local ntp3.local
+server ntp2.local
+server ntp3.local
+driftfile @CHRONYVARDIR@/drift
+local stratum 8 orphan
+manual
+allow 192.168.165.0/24
+rtcsync
+.fam
+.fi
+.if n .RE
+.sp
+The other servers would be the same, except the hostnames in the \fBinitstepslew\fP
+and \fBserver\fP directives would be modified to specify the other servers. Their
+clients might be configured to poll all three servers.
+.SS "RTC tracking"
+.sp
+This section considers a computer which has occasional connections to the
+Internet and is turned off between \(oqsessions\(cq. In this case, \fBchronyd\fP relies
+on the computer\(cqs RTC to maintain the time between the periods when it is
+powered up. It assumes that Linux is run exclusively on the computer. Dual\-boot
+systems might work; it depends what (if anything) the other system does to the
+RTC. On 2.6 and later kernels, if your motherboard has a HPET, you will need to
+enable the \fBHPET_EMULATE_RTC\fP option in your kernel configuration. Otherwise,
+\fBchronyd\fP will not be able to interact with the RTC device and will give up
+using it.
+.sp
+When the computer is connected to the Internet, \fBchronyd\fP has access to
+external NTP servers which it makes measurements from. These measurements are
+saved, and straight\-line fits are performed on them to provide an estimate of
+the computer\(cqs time error and rate of gaining or losing time.
+.sp
+When the computer is taken offline from the Internet, the best estimate of the
+gain or loss rate is used to free\-run the computer until it next goes online.
+.sp
+Whilst the computer is running, \fBchronyd\fP makes measurements of the RTC (via
+the \fI/dev/rtc\fP interface, which must be compiled into the kernel). An estimate
+is made of the RTC error at a particular RTC second, and the rate at which the
+RTC gains or loses time relative to true time.
+.sp
+When the computer is powered down, the measurement histories for all the NTP
+servers are saved to files, and the RTC tracking information is also
+saved to a file (if the \fBrtcfile\fP directive has been specified).
+These pieces of information are also saved if the \fBdump\fP
+and \fBwritertc\fP commands respectively are issued
+through \fBchronyc\fP.
+.sp
+When the computer is rebooted, \fBchronyd\fP reads the current RTC time and the RTC
+information saved at the last shutdown. This information is used to set the
+system clock to the best estimate of what its time would have been now, had it
+been left running continuously. The measurement histories for the servers are
+then reloaded.
+.sp
+The next time the computer goes online, the previous sessions\*(Aq measurements can
+contribute to the line\-fitting process, which gives a much better estimate of
+the computer\(cqs gain or loss rate.
+.sp
+One problem with saving the measurements and RTC data when the machine is shut
+down is what happens if there is a power failure; the most recent data will not
+be saved. Although \fBchronyd\fP is robust enough to cope with this, some
+performance might be lost. (The main danger arises if the RTC has been changed
+during the session, with the \fBtrimrtc\fP command in \fBchronyc\fP. Because of this,
+\fBtrimrtc\fP will make sure that a meaningful RTC file is saved after the
+change is completed).
+.sp
+The easiest protection against power failure is to put the \fBdump\fP and
+\fBwritertc\fP commands in the same place as the \fBoffline\fP command is issued to
+take \fBchronyd\fP offline; because \fBchronyd\fP free\-runs between online sessions, no
+parameters will change significantly between going offline from the Internet
+and any power failure.
+.sp
+A final point regards computers which are left running for extended periods and
+where it is desired to spin down the hard disc when it is not in use (e.g. when
+not accessed for 15 minutes). \fBchronyd\fP has been planned so it supports such
+operation; this is the reason why the RTC tracking parameters are not saved to
+disc after every update, but only when the user requests such a write, or
+during the shutdown sequence. The only other facility that will generate
+periodic writes to the disc is the \fBlog rtc\fP facility in the configuration
+file; this option should not be used if you want your disc to spin down.
+.sp
+To illustrate how a computer might be configured for this case, example
+configuration files are shown.
+.sp
+For the \fIchrony.conf\fP file, the following can be used as an example.
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net maxdelay 0.4 offline
+server bar.example.net maxdelay 0.4 offline
+server baz.example.net maxdelay 0.4 offline
+logdir /var/log/chrony
+log statistics measurements tracking
+driftfile @CHRONYVARDIR@/drift
+makestep 1.0 3
+maxupdateskew 100.0
+dumpdir @CHRONYVARDIR@
+rtcfile @CHRONYVARDIR@/rtc
+.fam
+.fi
+.if n .RE
+.sp
+\fBpppd\fP is used for connecting to the Internet. This runs two scripts
+\fI/etc/ppp/ip\-up\fP and \fI/etc/ppp/ip\-down\fP when the link goes online and offline
+respectively.
+.sp
+The relevant part of the \fI/etc/ppp/ip\-up\fP file is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc online
+.fam
+.fi
+.if n .RE
+.sp
+and the relevant part of the \fI/etc/ppp/ip\-down\fP script is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+@BINDIR@/chronyc \-m offline dump writertc
+.fam
+.fi
+.if n .RE
+.sp
+\fBchronyd\fP is started during the boot sequence with the \fB\-r\fP and \fB\-s\fP options.
+It might need to be started before any software that depends on the system clock
+not jumping or moving backwards, depending on the directives in \fBchronyd\fP\*(Aqs
+configuration file.
+.sp
+For the system shutdown, \fBchronyd\fP should receive a SIGTERM several seconds
+before the final SIGKILL; the SIGTERM causes the measurement histories and RTC
+information to be saved.
+.SS "Public NTP server"
+.sp
+\fBchronyd\fP can be configured to operate as a public NTP server, e.g. to join the
+.URL "https://www.pool.ntp.org/en/join.html" "pool.ntp.org" ""
+project. The configuration
+is similar to the NTP client with permanent connection, except it needs to
+allow client access from all addresses. It is recommended to find at least four
+good servers (e.g. from the pool, or on the NTP homepage). If the server has a
+hardware reference clock (e.g. a GPS receiver), it can be specified by the
+\fBrefclock\fP directive.
+.sp
+The amount of memory used for logging client accesses can be increased in order
+to enable clients to use the interleaved mode even when the server has a large
+number of clients, and better support rate limiting if it is enabled by the
+\fBratelimit\fP directive. The system timezone database, if it is
+kept up to date and includes the \fIright/UTC\fP timezone, can be used as a
+reliable source to determine when a leap second will be applied to UTC. The
+\fB\-r\fP option with the \fBdumpdir\fP directive shortens the time in which
+\fBchronyd\fP will not be able to serve time to its clients when it needs to be
+restarted (e.g. after upgrading to a newer version, or a change in the
+configuration).
+.sp
+The configuration file could look like:
+.sp
+.if n .RS 4
+.nf
+.fam C
+server foo.example.net iburst
+server bar.example.net iburst
+server baz.example.net iburst
+server qux.example.net iburst
+makestep 1.0 3
+rtcsync
+allow
+clientloglimit 100000000
+leapsectz right/UTC
+driftfile @CHRONYVARDIR@/drift
+dumpdir @CHRONYRUNDIR@
+.fam
+.fi
+.if n .RE
+.SH "SEE ALSO"
+.sp
+\fBchronyc(1)\fP, \fBchronyd(8)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony\-project.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/chronyc.adoc b/doc/chronyc.adoc
new file mode 100644
index 0000000..302d1d5
--- /dev/null
+++ b/doc/chronyc.adoc
@@ -0,0 +1,1555 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Stephen Wadeley  2016
+// Copyright (C) Miroslav Lichvar  2009-2017, 2019-2023
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chronyc(1)
+:doctype: manpage
+:man manual: User manual
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+
+chronyc - command-line interface for chrony daemon
+
+== SYNOPSIS
+
+*chronyc* [_OPTION_]... [_COMMAND_]...
+
+== DESCRIPTION
+
+*chronyc* is a command-line interface program which can be used to monitor
+*chronyd*'s performance and to change various operating parameters whilst it is
+running.
+
+If no commands are specified on the command line, *chronyc* will expect input
+from the user. The prompt _chronyc>_ will be displayed when it is being run
+from a terminal. If *chronyc*'s input or output are redirected from or to a file,
+the prompt will not be shown.
+
+There are two ways *chronyc* can access *chronyd*. One is the Internet
+Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is
+accessible locally by the root or _chrony_ user. By default, *chronyc* first
+tries to connect to the Unix domain socket. The compiled-in default path is
+_@CHRONYRUNDIR@/chronyd.sock_. If that fails (e.g. because *chronyc* is
+running under a non-root user), it will try to connect to 127.0.0.1 and then
+::1.
+
+Only the following monitoring commands, which do not affect the behaviour of
+*chronyd*, are allowed from the network: *activity*, *manual list*,
+*rtcdata*, *smoothing*, *sourcename*, *sources*, *sourcestats*, *tracking*,
+*waitsync*. The
+set of hosts from which *chronyd* will accept these commands can be configured
+with the <<chrony.conf.adoc#cmdallow,*cmdallow*>> directive in the *chronyd*'s
+configuration file or the <<cmdallow,*cmdallow*>> command in *chronyc*. By
+default, the commands are accepted only from localhost (127.0.0.1 or ::1).
+
+All other commands are allowed only through the Unix domain socket. When sent
+over the network, *chronyd* will respond with a '`Not authorised`' error, even
+if it is from localhost.
+
+Having full access to *chronyd* via *chronyc* is more or less equivalent to
+being able to modify the *chronyd*'s configuration file and restart it.
+
+== OPTIONS
+
+*-4*::
+With this option hostnames will be resolved only to IPv4 addresses.
+
+*-6*::
+With this option hostnames will be resolved only to IPv6 addresses.
+
+*-n*::
+This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
+DNS lookups. Long addresses will not be truncated to fit into the column.
+
+*-N*::
+This option enables printing of original hostnames or IP addresses of NTP
+sources that were specified in the configuration file, or *chronyc* commands.
+Without the *-n* and *-N* option, the printed hostnames are obtained from
+reverse DNS lookups and can be different from the specified hostnames.
+
+*-c*::
+This option enables printing of reports in a comma-separated values (CSV)
+format. Reverse DNS lookups will be disabled, time will be printed as number of
+seconds since the epoch, and values in seconds will not be converted to other
+units.
+
+*-e*::
+With this option each *chronyc* response will end with a line containing a
+single dot.
+
+*-d*::
+This option enables printing of debugging messages if *chronyc* was compiled
+with debugging support.
+
+*-m*::
+Normally, all arguments on the command line are interpreted as one command.
+With this option multiple commands can be specified. Each argument will be
+interpreted as a whole command.
+
+*-h* _host_::
+This option specifies the host to be contacted by *chronyc*. It can be
+specified with a hostname, IP address, or path to the local Unix domain socket.
+Multiple values can be specified as a comma-separated list to provide a
+fallback.
++
+The default value is _@CHRONYRUNDIR@/chronyd.sock,127.0.0.1,::1_, i.e. the host
+where *chronyc* is being run. First, it tries to connect to the Unix domain
+socket and if that fails (e.g. due to running under a non-root user), it
+will try to connect to 127.0.0.1 and then ::1.
+
+*-p* _port_::
+This option allows the user to specify the UDP port number which the target
+*chronyd* is using for its monitoring connections. This defaults to 323; there
+would rarely be a need to change this.
+
+*-f* _file_::
+This option is ignored and is provided only for compatibility.
+
+*-a*::
+This option is ignored and is provided only for compatibility.
+
+*-v*, *--version*::
+With this option *chronyc* displays its version number on the terminal and
+exits.
+
+*--help*::
+With this option *chronyc* displays a help message on the terminal and
+exits.
+
+== COMMANDS
+
+This section describes each of the commands available within the *chronyc*
+program.
+
+=== System clock
+
+[[tracking]]*tracking*::
+The *tracking* command displays parameters about the system's clock
+performance. An example of the output is shown below.
++
+----
+Reference ID    : CB00710F (foo.example.net)
+Stratum         : 3
+Ref time (UTC)  : Fri Jan 27 09:49:17 2017
+System time     : 0.000006523 seconds slow of NTP time
+Last offset     : -0.000006747 seconds
+RMS offset      : 0.000035822 seconds
+Frequency       : 3.225 ppm slow
+Residual freq   : -0.000 ppm
+Skew            : 0.129 ppm
+Root delay      : 0.013639022 seconds
+Root dispersion : 0.001100737 seconds
+Update interval : 64.2 seconds
+Leap status     : Normal
+----
++
+The fields are explained as follows:
++
+*Reference ID*:::
+This is the reference ID and name (or IP address) of the server to which the
+computer is currently synchronised. For IPv4 addresses, the reference ID is
+equal to the address and for IPv6 addresses it is the first 32 bits of the MD5
+sum of the address.
++
+If the reference ID is _7F7F0101_ and there is no name or IP address, it means
+the computer is not synchronised to any external source and that you have the
+_local_ mode operating (via the <<local,*local*>> command in *chronyc*, or the
+<<chrony.conf.adoc#local,*local*>> directive in the configuration file).
++
+The reference ID is printed as a hexadecimal number. Note that in older
+versions it used to be printed in quad-dotted notation and could be confused
+with an IPv4 address.
+*Stratum*:::
+The stratum indicates how many hops away from a computer with an attached
+reference clock we are. Such a computer is a stratum-1 computer, so the
+computer in the example is two hops away (i.e. _foo.example.net_ is a
+stratum-2 and is synchronised from a stratum-1).
+*Ref time*:::
+This is the time (UTC) at which the last measurement from the reference
+source was processed.
+*System time*:::
+This is the current offset between the NTP clock and system clock. The NTP
+clock is a software (virtual) clock maintained by *chronyd*, which is
+synchronised to the configured time sources and provides time to NTP clients.
+The system clock is synchronised to the NTP clock. To avoid steps in the
+system time, which might have adverse consequences for certain applications,
+the system clock is normally corrected only by speeding up or slowing down (up
+to the rate configured by the <<chrony.conf.adoc#maxslewrate,*maxslewrate*>>
+directive). If the offset is too large, this correction will take a very long
+time. A step can be forced by the <<makestep,*makestep*>> command, or the
+<<chrony.conf.adoc#makestep,*makestep*>> directive in the configuration file.
++
+Note that all other offsets reported by *chronyc* and most offsets in the log
+files are relative to the NTP clock, not the system clock.
+*Last offset*:::
+This is the estimated local offset on the last clock update. A positive value
+indicates the local time (as previously estimated true time) was ahead of the
+time sources.
+*RMS offset*:::
+This is a long-term average of the offset value.
+*Frequency*:::
+The '`frequency`' is the rate by which the system's clock would be wrong if
+*chronyd* was not correcting it. It is expressed in ppm (parts per million).
+For example, a value of 1 ppm would mean that when the system's clock thinks it
+has advanced 1 second, it has actually advanced by 1.000001 seconds relative to
+true time.
+*Residual freq*:::
+This shows the '`residual frequency`' for the currently selected reference
+source. This reflects any difference between what the measurements from the
+reference source indicate the frequency should be and the frequency currently
+being used.
++
+The reason this is not always zero is that a smoothing procedure is
+applied to the frequency. Each time a measurement from the reference
+source is obtained and a new residual frequency computed, the estimated
+accuracy of this residual is compared with the estimated accuracy (see
+'`skew`' next) of the existing frequency value. A weighted average is
+computed for the new frequency, with weights depending on these accuracies.
+If the measurements from the reference source follow a consistent trend, the
+residual will be driven to zero over time.
+*Skew*:::
+This is the estimated error bound on the frequency.
+*Root delay*:::
+This is the total of the network path delays to the stratum-1 computer from
+which the computer is ultimately synchronised.
+*Root dispersion*:::
+This is the total dispersion accumulated through all the computers back to
+the stratum-1 computer from which the computer is ultimately synchronised.
+Dispersion is due to system clock resolution, statistical measurement
+variations, etc.
++
+An absolute bound on the computer's clock accuracy (assuming the stratum-1
+computer is correct) is given by:
++
+----
+clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay)
+----
+*Update interval*:::
+This is the interval between the last two clock updates.
+*Leap status*:::
+This is the leap status, which can be _Normal_, _Insert second_, _Delete
+second_ or _Not synchronised_.
+
+[[makestep]]*makestep*::
+*makestep* _threshold_ _limit_::
+Normally *chronyd* will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+the system clock might be so far adrift that this slewing process would take a
+very long time to correct the system clock.
++
+The *makestep* command can be used in this situation. There are two forms of
+the command. The first form has no parameters. It tells *chronyd* to cancel any
+remaining correction that was being slewed and jump the system clock by the
+equivalent amount, making it correct immediately.
++
+The second form configures the automatic stepping, similarly to the
+<<chrony.conf.adoc#makestep,*makestep*>> directive. It has two parameters,
+stepping threshold (in seconds) and number of future clock updates for which
+the threshold will be active. This can be used with the <<burst,*burst*>>
+command to quickly make a new measurement and correct the clock by stepping if
+needed, without waiting for *chronyd* to complete the measurement and update
+the clock.
++
+----
+makestep 0.1 1
+burst 1/2
+----
++
+BE WARNED: Certain software will be seriously affected by such jumps in the
+system time. (That is the reason why *chronyd* uses slewing normally.)
+
+[[maxupdateskew]]*maxupdateskew* _skew-in-ppm_::
+This command has the same effect as the
+<<chrony.conf.adoc#maxupdateskew,*maxupdateskew*>> directive in the
+configuration file.
+
+[[waitsync]]*waitsync* [_max-tries_ [_max-correction_ [_max-skew_ [_interval_]]]]::
+The *waitsync* command waits for *chronyd* to synchronise.
++
+Up to four optional arguments can be specified. The first is the maximum number
+of tries before giving up and returning a non-zero error code. When 0 is
+specified, or there are no arguments, the number of tries will not be limited.
++
+The second and third arguments are the maximum allowed remaining correction of
+the system clock and the maximum allowed skew (in ppm) as reported by the
+<<tracking,*tracking*>> command in the *System time* and *Skew* fields. If not
+specified or zero, the value will not be checked.
++
+The fourth argument is the interval specified in seconds in which the check is
+repeated. The interval is 10 seconds by default.
++
+An example is:
++
+----
+waitsync 60 0.01
+----
++
+which will wait up to about 10 minutes (60 times 10 seconds) for *chronyd* to
+synchronise to a source and the remaining correction to be less than 10
+milliseconds.
+
+=== Time sources
+
+[[sources]]*sources* [*-a*] [*-v*]::
+This command displays information about the current time sources that *chronyd*
+is accessing.
++
+If the *-a* option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+_ID#XXXXXXXXXX_, which can be used in other commands expecting a source address.
++
+The *-v* option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
++
+----
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+#* GPS0                          0   4   377    11   -479ns[ -621ns] +/-  134ns
+^? foo.example.net               2   6   377    23   -923us[ -924us] +/-   43ms
+^+ bar.example.net               1   6   377    21  -2629us[-2619us] +/-   86ms
+----
++
+The columns are as follows:
++
+*M*:::
+This indicates the mode of the source. _^_ means a server, _=_ means a peer
+and _#_ indicates a locally connected reference clock.
+*S*:::
+This column indicates the selection state of the source.
+* _*_ indicates the best source which is currently selected for
+  synchronisation.
+* _+_ indicates other sources selected for synchronisation, which are combined
+  with the best source.
+* _-_ indicates a source which is considered to be selectable for
+  synchronisation, but not currently selected.
+* _x_ indicates a source which *chronyd* thinks is a falseticker (i.e. its
+  time is inconsistent with a majority of other sources, or sources specified
+  with the *trust* option).
+* _~_ indicates a source whose time appears to have too much variability.
+* _?_ indicates a source which is not considered to be selectable for
+  synchronisation for other reasons (e.g. unreachable, not synchronised, or
+  does not have enough measurements).
+{blank}:::
+The <<selectdata,*selectdata*>> command can be used to get more details about
+the selection state.
+*Name/IP address*:::
+This shows the name or the IP address of the source, or reference ID for reference
+clocks.
+*Stratum*:::
+This shows the stratum of the source, as reported in its most recently
+received sample. Stratum 1 indicates a computer with a locally attached
+reference clock. A computer that is synchronised to a stratum 1 computer is
+at stratum 2. A computer that is synchronised to a stratum 2 computer is at
+stratum 3, and so on.
+*Poll*:::
+This shows the rate at which the source is being polled, as a base-2
+logarithm of the interval in seconds. Thus, a value of 6 would indicate that
+a measurement is being made every 64 seconds. *chronyd* automatically varies
+the polling rate in response to prevailing conditions.
+*Reach*:::
+This shows the source's reachability register printed as an octal number. The
+register has 8 bits and is updated on every received or missed packet from
+the source. A value of 377 indicates that a valid reply was received for all
+from the last eight transmissions.
+*LastRx*:::
+This column shows how long ago the last good sample (which is shown in the next
+column) was received from the source. Measurements that failed some tests are
+ignored. This is normally in seconds. The letters _m_, _h_, _d_ or _y_ indicate
+minutes, hours, days, or years.
+*Last sample*:::
+This column shows the offset between the local clock and the source at the
+last measurement. The number in the square brackets shows the actual measured
+offset. This can be suffixed by _ns_ (indicating nanoseconds), _us_
+(indicating microseconds), _ms_ (indicating milliseconds), or _s_ (indicating
+seconds). The number to the left of the square brackets shows the original
+measurement, adjusted to allow for any slews applied to the local clock
+since. Positive offsets indicate that the local clock is ahead of the source.
+The number following the _+/-_ indicator shows the margin of error in the
+measurement (NTP root distance).
+
+[[sourcestats]]*sourcestats* [*-a*] [*-v*]::
+The *sourcestats* command displays information about the drift rate and offset
+estimation process for each of the sources currently being examined by
+*chronyd*.
++
+If the *-a* option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+_ID#XXXXXXXXXX_, which can be used in other commands expecting a source address.
++
+The *-v* option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
++
+An example report is:
++
+----
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+===============================================================================
+foo.example.net            11   5   46m     -0.001      0.045      1us    25us
+----
++
+The columns are as follows:
++
+*Name/IP Address*:::
+This is the name or IP address of the NTP server (or peer) or reference ID of the
+reference clock to which the rest of the line relates.
+*NP*:::
+This is the number of sample points currently being retained for the server.
+The drift rate and current offset are estimated by performing a linear
+regression through these points.
+*NR*:::
+This is the number of runs of residuals having the same sign following the
+last regression. If this number starts to become too small relative to the
+number of samples, it indicates that a straight line is no longer a good fit
+to the data. If the number of runs is too low, *chronyd* discards older
+samples and re-runs the regression until the number of runs becomes
+acceptable.
+*Span*:::
+This is the interval between the oldest and newest samples. If no unit is
+shown the value is in seconds. In the example, the interval is 46 minutes.
+*Frequency*:::
+This is the estimated residual frequency for the server, in parts per
+million. In this case, the computer's clock is estimated to be running 1 part
+in 10^9 slow relative to the server.
+*Freq Skew*:::
+This is the estimated error bounds on *Freq* (again in parts per million).
+*Offset*:::
+This is the estimated offset of the source.
+*Std Dev*:::
+This is the estimated sample standard deviation.
+
+[[selectdata]]*selectdata* [*-a*] [*-v*]::
+The *selectdata* command displays information specific to the selection of time
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. With the *-v* option, extra caption
+lines are shown as a reminder of the meanings of the columns.
++
+An example of the output is shown below.
++
+----
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+D foo.example.net           Y ----- --TR-    4   1.0   -61ms   +62ms  N
+* bar.example.net           N ----- -----    0   1.0 -6846us +7305us  N
++ baz.example.net           N ----- -----   10   1.0 -7381us +7355us  N
+----
++
+The columns are as follows:
++
+*S*:::
+This column indicates the state of the source after the last source selection.
+It is similar to the state reported by the *sources* command, but more
+states are reported.
+{blank}:::
+The following states indicate the source is not considered selectable for
+synchronisation:
+* _N_ - has the *noselect* option.
+* _s_ - is not synchronised.
+* _M_ - does not have enough measurements.
+* _d_ - has a root distance larger than the maximum distance (configured by the
+        <<chrony.conf.adoc#maxdistance,*maxdistance*>> directive).
+* _~_ - has a jitter larger than the maximum jitter (configured by the
+        <<chrony.conf.adoc#maxjitter,*maxjitter*>> directive).
+* _w_ - waits for other sources to get out of the _M_ state.
+* _S_ - has older measurements than other sources.
+* _O_ - has a stratum equal or larger than the orphan stratum (configured by
+        the <<chrony.conf.adoc#local,*local*>> directive).
+* _T_ - does not fully agree with sources that have the *trust* option.
+* _x_ - does not agree with other sources (falseticker).
+{blank}:::
+The following states indicate the source is considered selectable, but it is
+not currently used for synchronisation:
+* _W_ - waits for other sources to be selectable (required by the
+        <<chrony.conf.adoc#minsources,*minsources*>> directive, or
+        the *require* option of another source).
+* _P_ - another selectable source is preferred due to the *prefer* option.
+* _U_ - waits for a new measurement (after selecting a different best source).
+* _D_ - has, or recently had, a root distance which is too large to be combined
+        with other sources (configured by the
+        <<chrony.conf.adoc#combinelimit,*combinelimit*>> directive).
+{blank}:::
+The following states indicate the source is used for synchronisation of the
+local clock:
+* _+_ - combined with the best source.
+* _*_ - selected as the best source to update the reference data (e.g. root
+        delay, root dispersion).
+*Name/IP address*:::
+This column shows the name or IP address of the source if it is an NTP server,
+or the reference ID if it is a reference clock.
+*Auth*:::
+This column indicites whether an authentication mechanism is enabled for the
+source. _Y_ means yes and _N_ means no.
+*COpts*:::
+This column displays the configured selection options of the source.
+* _N_ indicates the *noselect* option.
+* _P_ indicates the *prefer* option.
+* _T_ indicates the *trust* option.
+* _R_ indicates the *require* option.
+*EOpts*:::
+This column displays the current effective selection options of the source,
+which can be different from the configured options due to the authentication
+selection mode (configured by the
+<<chrony.conf.adoc#authselectmode,*authselectmode*>> directive). The symbols
+are the same as in the *COpts* column.
+*Last*:::
+This column displays how long ago was the last measurement of the source made
+when the selection was performed.
+*Score*:::
+This column displays the current score against the source in the _*_ state. The
+scoring system avoids frequent reselection when multiple sources have a similar
+root distance. A value larger than 1 indicates this source was better than the
+_*_ source in recent selections. If the score reaches 10, the best source will
+be reselected and the scores will be reset to 1.
+*Interval*:::
+This column displays the lower and upper endpoint of the interval which was
+expected to contain the true offset of the local clock considering the root
+distance at the time of the selection.
+*Leap*:::
+This column displays the current leap status of the source.
+* _N_ indicates the normal status (no leap second).
+* _+_ indicates that a leap second will be inserted at the end of the month.
+* _-_ indicates that a leap second will be deleted at the end of the month.
+* _?_ indicates the unknown status (i.e. no valid measurement was made).
+
+[[selectopts]]*selectopts* _address|refid_ [_+|-option_]...::
+The *selectopts* command modifies the configured selection options of an NTP
+source specified by IP address (or the _ID#XXXXXXXXXX_ identifier used for
+unknown addresses), or a reference clock specified by reference ID as a string.
++
+The selection options can be added with the *+* symbol or removed with the *-*
+symbol. The *selectdata* command can be used to verify the configuration. The
+modified options will be applied in the next source selection, e.g. when a new
+measurement is made, or the *reselect* command is executed.
++
+An example of using this command is shown below.
++
+----
+selectopts 1.2.3.4 -noselect +prefer
+selectopts GPS +trust
+----
+
+[[reselect]]*reselect*::
+To avoid excessive switching between sources, *chronyd* can stay synchronised
+to a source even when it is not currently the best one among the available
+sources.
++
+The *reselect* command can be used to force *chronyd* to reselect the best
+synchronisation source.
+
+[[reselectdist]]*reselectdist* _distance_::
+The *reselectdist* command sets the reselection distance. It is equivalent to
+the <<chrony.conf.adoc#reselectdist,*reselectdist*>> directive in the
+configuration file.
+
+=== NTP sources
+
+[[activity]]*activity*::
+This command reports the number of servers and peers that are online and
+offline. If the *auto_offline* option is used in specifying some of the servers
+or peers, the *activity* command can be useful for detecting when all of them
+have entered the offline state after the network link has been disconnected.
++
+The report shows the number of servers and peers in 5 states:
++
+*online*:::
+the server or peer is currently online (i.e. assumed by *chronyd* to be reachable)
+*offline*:::
+the server or peer is currently offline (i.e. assumed by *chronyd* to be
+unreachable, and no measurements from it will be attempted.)
+*burst_online*:::
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the online state.
+*burst_offline*:::
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the offline state.
+*unresolved*:::
+the name of the server or peer was not resolved to an address yet; this source is
+not visible in the *sources* and *sourcestats* reports.
+
+[[authdata]]*authdata* [*-a*]::
+The *authdata* command displays information specific to authentication of NTP
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. An example of the output is
+shown below.
++
+----
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256 135m    0    0    8  100
+bar.example.net               SK    30   13  128    -    0    0    0    0
+baz.example.net                -     0    0    0    -    0    0    0    0
+----
++
+The columns are as follows:
++
+*Name/IP address*:::
+This column shows the name or the IP address of the source.
+*Mode*:::
+This column shows which mechanism authenticates NTP packets received from the
+source. _NTS_ means Network Time Security, _SK_ means a symmetric key, and _-_
+means authentication is disabled.
+*KeyID*:::
+This column shows an identifier of the key used for authentication. With a
+symmetric key, it is the ID from the <<chrony.conf.adoc#keyfile,key file>>.
+With NTS, it is a number starting at zero and incremented by one with each
+successful key establishment using the NTS-KE protocol, i.e. it shows how many
+times the key establishment was performed with this source.
+*Type*:::
+This columns shows an identifier of the algorithm used for authentication.
+With a symmetric key, it is the hash function or cipher specified in the key
+file. With NTS, it is an authenticated encryption with associated data (AEAD)
+algorithm, which is negotiated in the NTS-KE protocol. The following values can
+be reported:
+* 1: MD5
+* 2: SHA1
+* 3: SHA256
+* 4: SHA384
+* 5: SHA512
+* 6: SHA3-224
+* 7: SHA3-256
+* 8: SHA3-384
+* 9: SHA3-512
+* 10: TIGER
+* 11: WHIRLPOOL
+* 13: AES128
+* 14: AES256
+* 15: AEAD-AES-SIV-CMAC-256
+* 30: AEAD-AES-128-GCM-SIV
+*KLen*:::
+This column shows the length of the key in bits.
+*Last*:::
+This column shows how long ago the last successful key establishment was
+performed. It is in seconds, or letters _m_, _h_, _d_ or _y_ indicate minutes,
+hours, days, or years.
+*Atmp*:::
+This column shows the number of attempts to perform the key establishment since
+the last successful key establishment. A number larger than 1 indicates a
+problem with the network or server.
+*NAK*:::
+This column shows whether an NTS NAK was received since the last request.
+A NAK indicates that authentication failed on the server side due to
+*chronyd* using a cookie which is no longer valid and that it needs to perform
+the key establishment again in order to get new cookies.
+*Cook*:::
+This column shows the number of NTS cookies that *chronyd* currently has. If
+the key establishment was successful, a number smaller than 8 indicates a
+problem with the network or server.
+*CLen*:::
+This column shows the length in bytes of the NTS cookie which will be used in
+the next request.
+
+[[ntpdata]]*ntpdata* [_address_]::
+The *ntpdata* command displays the last valid measurement and other
+NTP-specific information about the specified NTP source, or all NTP sources
+(with a known address) if no address was specified. An example of the output is
+shown below.
++
+----
+Remote address  : 203.0.113.15 (CB00710F)
+Remote port     : 123
+Local address   : 203.0.113.74 (CB00714A)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 10 (1024 seconds)
+Precision       : -24 (0.000000060 seconds)
+Root delay      : 0.000015 seconds
+Root dispersion : 0.000015 seconds
+Reference ID    : 47505300 (GPS)
+Reference time  : Fri Nov 25 15:22:12 2016
+Offset          : -0.000060878 seconds
+Peer delay      : 0.000175634 seconds
+Peer dispersion : 0.000000681 seconds
+Response time   : 0.000053050 seconds
+Jitter asymmetry: +0.00
+NTP tests       : 111 111 1111
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 24
+Total RX        : 24
+Total valid RX  : 24
+Total good RX   : 22
+----
++
+The fields are explained as follows:
++
+*Remote address*:::
+The IP address of the NTP server or peer, and the corresponding reference ID.
+*Remote port*:::
+The UDP port number to which the request was sent. The standard NTP port is
+123.
+*Local address*:::
+The local IP address which received the response, and the corresponding
+reference ID.
+*Leap status*:::
+*Version*:::
+*Mode*:::
+*Stratum*:::
+*Poll interval*:::
+*Precision*:::
+*Root delay*:::
+*Root dispersion*:::
+*Reference ID*:::
+*Reference time*:::
+The NTP values from the last valid response.
+*Offset*:::
+*Peer delay*:::
+*Peer dispersion*:::
+The measured values.
+*Response time*:::
+The time the server or peer spent in processing of the request and waiting
+before sending the response.
+*Jitter asymmetry*:::
+The estimated asymmetry of network jitter on the path to the source. The
+asymmetry can be between -0.5 and 0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent
+from the source back.
+*NTP tests*:::
+Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum
+delay, delay ratio, delay dev ratio (or delay quantile), and synchronisation
+loop.
+*Interleaved*:::
+This shows if the response was in the interleaved mode.
+*Authenticated*:::
+This shows if the response was authenticated.
+*TX timestamping*:::
+The source of the local transmit timestamp. Valid values are _Daemon_,
+_Kernel_, and _Hardware_.
+*RX timestamping*:::
+The source of the local receive timestamp.
+*Total TX*:::
+The number of packets sent to the source.
+*Total RX*:::
+The number of all packets received from the source.
+*Total valid RX*:::
+The number of packets which passed the first two groups of NTP tests.
+*Total good RX*:::
+The number of packets which passed all three groups of NTP tests, i.e. the NTP
+measurement was accepted.
+
+[[add_peer]]*add peer* _name_ [_option_]...::
+The *add peer* command allows a new NTP peer to be added whilst
+*chronyd* is running.
++
+Following the words *add peer*, the syntax of the following
+parameters and options is identical to that for the
+<<chrony.conf.adoc#peer,*peer*>> directive in the configuration file.
++
+An example of using this command is shown below.
++
+----
+add peer foo.example.net minpoll 6 maxpoll 10 key 25
+----
+
+[[add_pool]]*add pool* _name_ [_option_]...::
+The *add pool* command allows a pool of NTP servers to be added whilst
+*chronyd* is running.
++
+Following the words *add pool*, the syntax of the following parameters and
+options is identical to that for the <<chrony.conf.adoc#pool,*pool*>>
+directive in the configuration file.
++
+An example of using this command is shown below:
++
+----
+add pool foo.example.net maxsources 3 iburst
+----
+
+[[add_server]]*add server* _name_ [_option_]...::
+The *add server* command allows a new NTP server to be added whilst
+*chronyd* is running.
++
+Following the words *add server*, the syntax of the following parameters and
+options is identical to that for the <<chrony.conf.adoc#server,*server*>>
+directive in the configuration file.
++
+An example of using this command is shown below:
++
+----
+add server foo.example.net minpoll 6 maxpoll 10 key 25
+----
+
+[[delete]]*delete* _address_::
+The *delete* command allows an NTP server or peer to be removed
+from the current set of sources.
+
+[[burst]]
+*burst* _good_/_max_ [_mask_/_masked-address_]::
+*burst* _good_/_max_ [_masked-address_/_masked-bits_]::
+*burst* _good_/_max_ [_address_]::
+The *burst* command tells *chronyd* to make a set of measurements to each of
+its NTP sources over a short duration (rather than the usual periodic
+measurements that it makes). After such a burst, *chronyd* will revert to the
+previous state for each source. This might be either online, if the source was
+being periodically measured in the normal way, or offline, if the source had
+been indicated as being offline. (A source can be switched between the online
+and offline states with the <<online,*online*>> and <<offline,*offline*>>
+commands.)
++
+The _mask_ and _masked-address_ arguments are optional, in which case *chronyd*
+will initiate a burst for all of its currently defined sources.
++
+The arguments have the following meaning and format:
++
+_good_:::
+This defines the number of good measurements that *chronyd* will want to
+obtain from each source. A measurement is good if it passes certain tests,
+for example, the round trip time to the source must be acceptable. (This
+allows *chronyd* to reject measurements that are likely to be bogus.)
+_max_:::
+This defines the maximum number of measurements that *chronyd* will attempt
+to make, even if the required number of good measurements has not been
+obtained.
+_mask_:::
+This is an IP address with which the IP address of each of *chronyd*'s
+sources is to be masked.
+_masked-address_:::
+This is an IP address. If the masked IP address of a source matches this
+value then the burst command is applied to that source.
+_masked-bits_:::
+This can be used with _masked-address_ for CIDR notation, which is a shorter
+alternative to the form with mask.
+_address_:::
+This is an IP address or a hostname. The burst command is applied only to
+that source.
+{blank}::
++
+If no _mask_ or _masked-address_ arguments are provided, every source will be
+matched.
++
+An example of the two-argument form of the command is:
++
+----
+burst 2/10
+----
++
+This will cause *chronyd* to attempt to get two good measurements from each
+source, stopping after two have been obtained, but in no event will it try more
+than ten probes to the source.
++
+Examples of the four-argument form of the command are:
++
+----
+burst 2/10 255.255.0.0/1.2.0.0
+burst 2/10 2001:db8:789a::/48
+----
++
+In the first case, the two out of ten sampling will only be applied to sources
+whose IPv4 addresses are of the form _1.2.x.y_, where _x_ and _y_ are
+arbitrary. In the second case, the sampling will be applied to sources whose
+IPv6 addresses have first 48 bits equal to _2001:db8:789a_.
++
+Example of the three-argument form of the command is:
++
+----
+burst 2/10 foo.example.net
+----
+
+[[maxdelay]]*maxdelay* _address_ _delay_::
+This allows the *maxdelay* option for one of the sources to be modified, in the
+same way as specifying the *maxdelay* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxdelaydevratio]]*maxdelaydevratio* _address_ _ratio_::
+This allows the *maxdelaydevratio* option for one of the sources to be
+modified, in the same way as specifying the *maxdelaydevratio* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxdelayratio]]*maxdelayratio* _address_ _ratio_::
+This allows the *maxdelayratio* option for one of the sources to be modified,
+in the same way as specifying the *maxdelayratio* option for the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[maxpoll]]*maxpoll* _address_ _maxpoll_::
+The *maxpoll* command is used to modify the maximum polling interval for one of
+the current set of sources. It is equivalent to the *maxpoll* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
++
+Note that the new maximum polling interval only takes effect after the next
+measurement has been made.
+
+[[minpoll]]*minpoll* _address_ _minpoll_::
+The *minpoll* command is used to modify the minimum polling interval for one of
+the current set of sources. It is equivalent to the *minpoll* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
++
+Note that the new minimum polling interval only takes effect after the next
+measurement has been made.
+
+[[minstratum]]*minstratum* _address_ _minstratum_::
+The *minstratum* command is used to modify the minimum stratum for one of the
+current set of sources. It is equivalent to the *minstratum* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[offline]]
+*offline* [_address_]::
+*offline* [_masked-address_/_masked-bits_]::
+*offline* [_mask_/_masked-address_]::
+The *offline* command is used to warn *chronyd* that the network connection to
+a particular host or hosts is about to be lost, e.g. on computers with
+intermittent connection to their time sources.
++
+Another case where *offline* could be used is where a computer serves time to a
+local group of computers, and has a permanent connection to true time servers
+outside the organisation. However, the external connection is heavily loaded at
+certain times of the day and the measurements obtained are less reliable at
+those times. In this case, it is probably most useful to determine the
+gain or loss rate during the quiet periods and let the whole network coast through
+the loaded periods. The *offline* and *online* commands can be used to achieve
+this.
++
+There are four forms of the *offline* command. The first form is a wildcard,
+meaning all sources (including sources that do not have a known address yet).
+The second form allows an IP address mask and a masked
+address to be specified. The third form uses CIDR notation. The fourth form
+uses an IP address or a hostname. These forms are illustrated below.
++
+----
+offline
+offline 255.255.255.0/1.2.3.0
+offline 2001:db8:789a::/48
+offline foo.example.net
+----
++
+The second form means that the *offline* command is to be applied to any source
+whose IPv4 address is in the _1.2.3_ subnet. (The host's address is logically
+and-ed with the mask, and if the result matches the _masked-address_ the host
+is processed.) The third form means that the command is to be applied to all
+sources whose IPv6 addresses have their first 48 bits equal to _2001:db8:789a_. The
+fourth form means that the command is to be applied only to that one source.
++
+The wildcard form of the address is equivalent to:
++
+----
+offline 0.0.0.0/0.0.0.0
+offline ::/0
+----
+
+[[online]]
+*online* [_address_]::
+*online* [_masked-address_/_masked-bits_]::
+*online* [_mask_/_masked-address_]::
+The *online* command is opposite in function to the <<offline,*offline*>>
+command. It is used to advise *chronyd* that network connectivity to a
+particular source or sources has been restored.
++
+The syntax is identical to that of the <<offline,*offline*>> command.
+
+[[onoffline]]
+*onoffline*::
+The *onoffline* command tells *chronyd* to switch all sources that have a known
+address to the online or
+offline status according to the current network configuration. A source is
+considered online if it is possible to send requests to it, i.e. a network
+route to the source is present.
+
+[[polltarget]]*polltarget* _address_ _polltarget_::
+The *polltarget* command is used to modify the poll target for one of the
+current set of sources. It is equivalent to the *polltarget* option in the
+<<chrony.conf.adoc#server,*server*>> directive in the configuration file.
+
+[[refresh]]*refresh*::
+The *refresh* command can be used to force *chronyd* to resolve the names of
+configured NTP sources to IP addresses again and replace any addresses missing
+in the list of resolved addresses.
++
+Sources that stop responding are replaced with newly resolved addresses
+automatically after 8 polling intervals. This command can be used to replace
+them immediately, e.g. after suspending and resuming the machine in a different
+network.
++
+Note that with pools which have more than 16 addresses, or not all IPv4 or IPv6
+addresses are included in a single DNS response (e.g. pool.ntp.org), this
+command might replace the addresses even if they are still in the pool.
+
+[[reload]]*reload* *sources*::
+The *reload sources* command causes *chronyd* to re-read all _*.sources_ files
+from the directories specified by the
+<<chrony.conf.adoc#sourcedir,*sourcedir*>> directive.
+
+[[sourcename]]*sourcename* _address_::
+The *sourcename* command prints the original hostname or address that was
+specified for an NTP source in the configuration file, or the *add* command.
+This command is an alternative to the *-N* option, which can be useful in
+scripts.
++
+Note that different NTP sources can share the same name, e.g. servers from a
+pool.
+
+=== Manual time input
+
+[[manual]]
+*manual* *on*::
+*manual* *off*::
+*manual* *delete* _index_::
+*manual* *list*::
+*manual* *reset*::
+The manual command enables and disables use of the <<settime,*settime*>>
+command, and is used to modify the behaviour of the manual clock driver.
++
+The *on* form of the command enables use of the *settime* command.
++
+The *off* form of the command disables use of the *settime* command.
++
+The *list* form of the command lists all the samples currently stored in
+*chronyd*. The output is illustrated below.
++
+----
+210 n_samples = 1
+#    Date  Time(UTC)    Slewed   Original   Residual
+====================================================
+ 0 27Jan99 22:09:20       0.00       0.97       0.00
+----
++
+The columns are as as follows:
++
+. The sample index (used for the *manual delete* command).
+. The date and time of the sample.
+. The system clock error when the timestamp was entered, adjusted to allow
+  for changes made to the system clock since.
+. The system clock error when the timestamp was entered, as it originally was
+  (without allowing for changes to the system clock since).
+. The regression residual at this point, in seconds. This allows '`outliers`'
+  to be easily spotted, so that they can be deleted using the *manual delete*
+  command.
+{blank}::
++
+The *delete* form of the command deletes a single sample. The parameter is the
+index of the sample, as shown in the first column of the output from *manual
+list*. Following deletion of the data point, the current error and drift rate
+are re-estimated from the remaining data points and the system clock trimmed if
+necessary. This option is intended to allow '`outliers`' to be discarded, i.e.
+samples where the administrator realises they have entered a very poor
+timestamp.
++
+The *reset* form of the command deletes all samples at once. The system clock
+is left running as it was before the command was entered.
+
+[[settime]]*settime* _time_::
+The *settime* command allows the current time to be entered manually, if this
+option has been configured into *chronyd*. (It can be configured either with
+the <<chrony.conf.adoc#manual,*manual*>> directive in the configuration file,
+or with the <<manual,*manual*>> command of *chronyc*.)
++
+It should be noted that the computer's sense of time will only be as accurate
+as the reference you use for providing this input (e.g. your watch), as well as
+how well you can time the press of the return key.
++
+Providing your computer's time zone is set up properly, you will be able to
+enter a local time (rather than UTC).
++
+The response to a successful *settime* command indicates the amount that the
+computer's clock was wrong. It should be apparent from this if you have entered
+the time wrongly, e.g. with the wrong time zone.
++
+The rate of drift of the system clock is estimated by a regression process
+using the entered measurement and all previous measurements entered during the
+present run of *chronyd*. However, the entered measurement is used for
+adjusting the current clock offset (rather than the estimated intercept from
+the regression, which is ignored). Contrast what happens with the
+<<manual,*manual delete*>> command, where the intercept is used to set the
+current offset (since there is no measurement that has just been entered in
+that case).
++
+The time is parsed by the public domain _getdate_ algorithm. Consequently, you
+can only specify time to the nearest second.
++
+Examples of inputs that are valid are shown below:
++
+----
+settime 16:30
+settime 16:30:05
+settime Nov 21, 2015 16:30:05
+----
++
+For a full description of getdate, see the getdate documentation
+(bundled, for example, with the source for GNU tar).
+
+=== NTP access
+
+[[accheck]]*accheck* _address_::
+This command allows you to check whether client NTP access is allowed from a
+particular host.
++
+Examples of use, showing a named host and a numeric IP address, are as follows:
++
+----
+accheck foo.example.net
+accheck 1.2.3.4
+accheck 2001:db8::1
+----
++
+This command can be used to examine the effect of a series of *allow*, *allow
+all*, *deny*, and *deny all* commands specified either via *chronyc*, or in
+*chronyd*'s configuration file.
+
+[[clients]]*clients* [*-p* _packets_] [*-k*] [*-r*]::
+This command shows a list of clients that have accessed the server, through
+the NTP, command, or NTS-KE port. It does not include accesses over the Unix
+domain command socket.
++
+The *-p* option specifies the minimum number of received NTP or command
+packets, or accepted NTS-KE connections, needed to include a client in the
+list. The default value is 0, i.e. all clients are reported. With the *-k*
+option the last four columns will show the NTS-KE accesses instead of command
+accesses. If the *-r* option is specified, *chronyd* will reset the counters of
+received and dropped packets or connections after reporting the current values.
++
+An example of the output is:
++
+----
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+localhost                       2      0   2   -   133      15      0  -1     7
+foo.example.net                12      0   6   -    23       0      0   -     -
+----
++
+Each row shows the data for a single host. Only hosts that have passed the host
+access checks (set with the <<allow,*allow*>>, <<deny,*deny*>>,
+<<cmdallow,*cmdallow*>> and <<cmddeny,*cmddeny*>> commands or configuration
+file directives) are logged. The intervals are displayed as a power of 2 in
+seconds.
++
+The columns are as follows:
++
+. The hostname of the client.
+. The number of NTP packets received from the client.
+. The number of NTP packets dropped to limit the response rate.
+. The average interval between NTP packets.
+. The average interval between NTP packets after limiting the response rate.
+. Time since the last NTP packet was received
+. The number of command packets or NTS-KE connections received/accepted from
+  the client.
+. The number of command packets or NTS-KE connections dropped to limit the
+  response rate.
+. The average interval between command packets or NTS-KE connections.
+. Time since the last command packet or NTS-KE connection was
+  received/accepted.
+
+[[serverstats]]*serverstats*::
+The *serverstats* command displays NTP and command server statistics.
++
+An example of the output is shown below.
++
+----
+NTP packets received       : 1598
+NTP packets dropped        : 8
+Command packets received   : 19
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 3
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 189
+Interleaved NTP packets    : 43
+NTP timestamps held        : 44
+NTP timestamp span         : 120
+NTP daemon RX timestamps   : 0
+NTP daemon TX timestamps   : 1537
+NTP kernel RX timestamps   : 1590
+NTP kernel TX timestamps   : 43
+NTP hardware RX timestamps : 0
+NTP hardware TX timestamps : 0
+----
++
+The fields have the following meaning:
++
+*NTP packets received*:::
+The number of valid NTP requests received by the server.
+*NTP packets dropped*:::
+The number of NTP requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ratelimit,*ratelimit*>> directive).
+*Command packets received*:::
+The number of command requests received by the server.
+*Command packets dropped*:::
+The number of command requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#cmdratelimit,*cmdratelimit*>> directive).
+*Client log records dropped*:::
+The number of client log records dropped by the server to limit the memory use
+(configured by the <<chrony.conf.adoc#clientloglimit,*clientloglimit*>>
+directive).
+*NTS-KE connections accepted*:::
+The number of NTS-KE connections accepted by the server.
+*NTS-KE connections dropped*:::
+The number of NTS-KE connections dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ntsratelimit,*ntsratelimit*>> directive).
+*Authenticated NTP packets*:::
+The number of received NTP requests that were authenticated (with a symmetric
+key or NTS).
+*Interleaved NTP packets*:::
+The number of received NTP requests that were detected to be in the interleaved
+mode.
+*NTP timestamps held*:::
+The number of pairs of receive and transmit timestamps that the server is
+currently holding in memory for clients using the interleaved mode.
+*NTP timestamp span*:::
+The interval (in seconds) covered by the currently held NTP timestamps.
+*NTP daemon RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+daemon.
+*NTP daemon TX timestamps*:::
+The number of NTP responses which included a transmit timestamp captured by the
+daemon.
+*NTP kernel RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+kernel.
+*NTP kernel TX timestamps*:::
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the kernel.
+*NTP hardware RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+NIC.
+*NTP hardware TX timestamps*:::
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the NIC.
+
+[[allow]]*allow* [*all*] [_subnet_]::
+The effect of the allow command is identical to the
+<<chrony.conf.adoc#allow,*allow*>> directive in the configuration file.
++
+The syntax is illustrated in the following examples:
++
+----
+allow 1.2.3.4
+allow all 3.4.5.0/24
+allow 2001:db8:789a::/48
+allow 0/0
+allow ::/0
+allow
+allow all
+----
+
+[[deny]]*deny* [*all*] [_subnet_]::
+The effect of the allow command is identical to the
+<<chrony.conf.adoc#deny,*deny*>> directive in the configuration file.
++
+The syntax is illustrated in the following examples:
++
+----
+deny 1.2.3.4
+deny all 3.4.5.0/24
+deny 2001:db8:789a::/48
+deny 0/0
+deny ::/0
+deny
+deny all
+----
+
+[[local]]
+*local* [_option_]...::
+*local* *off*::
+The *local* command allows *chronyd* to be told that it is to appear as a
+reference source, even if it is not itself properly synchronised to an external
+source. This can be used on isolated networks, to allow a computer to be the
+primary time server for other computers.
++
+The first form enables the local reference mode on the host. The syntax is
+identical to the <<chrony.conf.adoc#local,*local*>> directive in the
+configuration file.
++
+The second form disables the local reference mode.
+
+[[smoothing]]*smoothing*::
+The *smoothing* command displays the current state of the NTP server time
+smoothing, which can be enabled with the
+<<chrony.conf.adoc#smoothtime,*smoothtime*>> directive. An example of the
+output is shown below.
++
+----
+Active         : Yes
+Offset         : +1.000268817 seconds
+Frequency      : -0.142859 ppm
+Wander         : -0.010000 ppm per second
+Last update    : 17.8 seconds ago
+Remaining time : 19988.4 seconds
+----
++
+The fields are explained as follows:
++
+*Active*:::
+This shows if the server time smoothing is currently active. Possible values
+are _Yes_ and _No_. If the *leaponly* option is included in the *smoothtime*
+directive, _(leap second only)_ will be shown on the line.
+*Offset*:::
+This is the current offset applied to the time sent to NTP clients. Positive
+value means the clients are getting time that's ahead of true time.
+*Frequency*:::
+The current frequency offset of the served time. Negative value means the
+time observed by clients is running slower than true time.
+*Wander*:::
+The current frequency wander of the served time. Negative value means the
+time observed by clients is slowing down.
+*Last update*:::
+This field shows how long ago the time smoothing process was updated, e.g.
+*chronyd* accumulated a new measurement.
+*Remaining time*:::
+The time it would take for the smoothing process to get to zero offset and
+frequency if there were no more updates.
+
+[[smoothtime]]
+*smoothtime* *activate*::
+*smoothtime* *reset*::
+The *smoothtime* command can be used to activate or reset the server time
+smoothing process if it is configured with the
+<<chrony.conf.adoc#smoothtime,*smoothtime*>> directive.
+
+=== Monitoring access
+
+[[cmdaccheck]]*cmdaccheck* _address_::
+This command is similar to the <<accheck,*accheck*>> command, except that it is
+used to check whether monitoring access is permitted from a named host.
++
+Examples of use are as follows:
++
+----
+cmdaccheck foo.example.net
+cmdaccheck 1.2.3.4
+cmdaccheck 2001:db8::1
+----
+
+[[cmdallow]]*cmdallow* [*all*] [_subnet_]::
+This is similar to the <<allow,*allow*>> command, except that it is used to
+allow particular hosts or subnets to use *chronyc* to monitor with *chronyd* on
+the current host.
+
+[[cmddeny]]*cmddeny* [*all*] [_subnet_]::
+This is similar to the <<deny,*deny*>> command, except that it is used to allow
+particular hosts or subnets to use *chronyc* to monitor *chronyd* on the
+current host.
+
+=== Real-time clock (RTC)
+
+[[rtcdata]]*rtcdata*::
+The *rtcdata* command displays the current RTC parameters.
++
+An example output is shown below.
++
+----
+RTC ref time (GMT) : Sat May 30 07:25:56 2015
+Number of samples  : 10
+Number of runs     : 5
+Sample span period :  549
+RTC is fast by     :    -1.632736 seconds
+RTC gains time at  :  -107.623 ppm
+----
++
+The fields have the following meaning:
++
+*RTC ref time (GMT)*:::
+This is the RTC reading the last time its error was measured.
+*Number of samples*:::
+This is the number of previous measurements being used to determine the RTC
+gain or loss rate.
+*Number of runs*:::
+This is the number of runs of residuals of the same sign following the
+regression fit for (RTC error) versus (RTC time). A value which is small
+indicates that the measurements are not well approximated by a linear model,
+and that the algorithm will tend to delete the older measurements to improve
+the fit.
+*Sample span period*:::
+This is the period that the measurements span (from the oldest to the
+newest). Without a unit the value is in seconds; suffixes _m_ for minutes,
+_h_ for hours, _d_ for days or _y_ for years can be used.
+*RTC is fast by*:::
+This is the estimate of how many seconds fast the RTC when it thought
+the time was at the reference time (above). If this value is large, you
+might (or might not) want to use the <<trimrtc,*trimrtc*>> command to bring the
+RTC into line with the system clock. (Note, a large error will not affect
+*chronyd*'s operation, unless it becomes so big as to start causing rounding
+errors.)
+*RTC gains time at*:::
+This is the amount of time gained (positive) or lost (negative) by the real
+time clock for each second that it ticks. It is measured in parts per
+million. So if the value shown was +1, suppose the RTC was exactly right when
+it crosses a particular second boundary. Then it would be 1 microsecond fast
+when it crosses its next second boundary.
+
+[[trimrtc]]*trimrtc*::
+The *trimrtc* command is used to correct the system's real-time clock (RTC) to
+the main system clock. It has no effect if the error between the two clocks is
+currently estimated at less than a second.
++
+The command takes no arguments. It performs the following steps (if the RTC is
+more than 1 second away from the system clock):
++
+. Remember the currently estimated gain or loss rate of the RTC and flush the
+  previous measurements.
+. Step the real-time clock to bring it within a second of the system clock.
+. Make several measurements to accurately determine the new offset between
+  the RTC and the system clock (i.e. the remaining fraction of a second
+  error).
+. Save the RTC parameters to the RTC file (specified with the
+  <<chrony.conf.adoc#rtcfile,*rtcfile*>> directive in the configuration file).
+{blank}::
++
+The last step is done as a precaution against the computer suffering a power
+failure before either the daemon exits or the <<writertc,*writertc*>> command
+is issued.
++
+*chronyd* will still work perfectly well both whilst operating and across
+machine reboots even if the *trimrtc* command is never used (and the RTC is
+allowed to drift away from true time). The *trimrtc* command is provided as a
+method by which it can be corrected, in a manner compatible with *chronyd*
+using it to maintain accurate time across machine reboots.
++
+The *trimrtc* command can be executed automatically by *chronyd* with the
+<<chrony.conf.adoc#rtcautotrim,*rtcautotrim*>> directive in the configuration
+file.
+
+[[writertc]]*writertc*::
+The *writertc* command writes the currently estimated error and gain or loss rate
+parameters for the RTC to the RTC file (specified with the
+<<chrony.conf.adoc#rtcfile,*rtcfile*>> directive). This information is also
+written automatically when *chronyd* is killed (by the SIGHUP, SIGINT, SIGQUIT
+or SIGTERM signals) or when the <<trimrtc,*trimrtc*>> command is issued.
+
+=== Other daemon commands
+
+[[cyclelogs]]*cyclelogs*::
+The *cyclelogs* command causes all of *chronyd*'s open log files to be closed
+and re-opened. This allows them to be renamed so that they can be periodically
+purged. An example of how to do this is shown below.
++
+----
+# mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
+# chronyc cyclelogs
+# rm /var/log/chrony/measurements1.log
+----
+
+[[dump]]*dump*::
+The *dump* command causes *chronyd* to write its current history of
+measurements for each of its sources to dump files in the directory specified
+in the configuration file by the <<chrony.conf.adoc#dumpdir,*dumpdir*>>
+directive and also write server NTS keys and client NTS cookies to the
+directory specified by the <<chrony.conf.adoc#ntsdumpdir1,*ntsdumpdir*>>
+directive. Note that *chronyd* does this automatically when it exits. This
+command is mainly useful for inspection whilst *chronyd* is running.
+
+[[rekey]]*rekey*::
+The *rekey* command causes *chronyd* to re-read the key file specified in the
+configuration file by the <<chrony.conf.adoc#keyfile,*keyfile*>> directive. It
+also re-reads the server NTS keys if
+<<chrony.conf.adoc#ntsdumpdir2,*ntsdumpdir*>> is specified and
+<<chrony.conf.adoc#ntsrotate,automatic rotation>> is disabled in the
+configuration file.
+
+[[reset]]*reset* *sources*::
+The *reset sources* command causes *chronyd* to drop all measurements and
+switch to the unsynchronised state. This command can help *chronyd* with
+recovery when the measurements are known to be no longer valid or accurate,
+e.g. due to moving the computer to a different network, or resuming the
+computer from a low-power state (which resets the system clock). *chronyd* will
+drop the measurements automatically when it detects the clock has made an
+unexpected jump, but the detection is not completely reliable.
+
+[[shutdown]]*shutdown*::
+The *shutdown* command causes *chronyd* to exit. This is equivalent to sending
+the process the SIGTERM signal.
+
+=== Client commands
+
+[[dns]]*dns* _option_::
+The *dns* command configures how hostnames and IP addresses are resolved in
+*chronyc*. IP addresses can be resolved to hostnames when printing results of
+<<sources,*sources*>>, <<sourcestats,*sourcestats*>>, <<tracking,*tracking*>>
+and <<clients,*clients*>> commands. Hostnames are resolved in commands that
+take an address as argument.
++
+There are five options:
++
+*dns -n*:::
+Disables resolving IP addresses to hostnames. Raw IP addresses will be
+displayed.
+*dns +n*:::
+Enables resolving IP addresses to hostnames. This is the default unless
+*chronyc* was started with *-n* option.
+*dns -4*:::
+Resolves hostnames only to IPv4 addresses.
+*dns -6*:::
+Resolves hostnames only to IPv6 addresses.
+*dns -46*:::
+Resolves hostnames to both address families. This is the default behaviour
+unless *chronyc* was started with the *-4* or *-6* option.
+
+[[timeout]]*timeout* _timeout_::
+The *timeout* command sets the initial timeout for *chronyc* requests in
+milliseconds. If no response is received from *chronyd*, the timeout is doubled
+and the request is resent. The maximum number of retries is configured with the
+<<retries,*retries*>> command.
++
+By default, the timeout is 1000 milliseconds.
+
+[[retries]]*retries* _retries_::
+The *retries* command sets the maximum number of retries for *chronyc* requests
+before giving up. The response timeout is controlled by the
+<<timeout,*timeout*>> command.
++
+The default is 2.
+
+[[keygen]]*keygen* [_id_ [_type_ [_bits_]]]::
+The *keygen* command generates a key that can be added to the
+key file (specified with the <<chrony.conf.adoc#keyfile,*keyfile*>> directive)
+to allow NTP authentication between server and client, or peers. The key is
+generated from the _/dev/urandom_ device and it is printed to standard output.
++
+The command has three optional arguments. The first argument is the key number
+(by default 1), which will be specified with the *key* option of the *server*
+or *peer* directives in the configuration file. The second argument is the name
+of the hash function or cipher (by default SHA1, or MD5 if SHA1 is not
+available). The third argument is the length of the key in bits if a hash
+function was selected, between 80 and 4096 bits (by default 160 bits).
++
+An example is:
++
+----
+keygen 73 SHA1 256
+----
++
+which generates a 256-bit SHA1 key with number 73. The printed line should
+then be securely transferred and added to the key files on both server and
+client, or peers. A different key should be generated for each client or peer.
++
+An example using the AES128 cipher is:
++
+----
+keygen 151 AES128
+----
+
+[[exit]]*exit*::
+[[quit]]*quit*::
+The *exit* and *quit* commands exit from *chronyc* and return the user to the shell.
+
+[[help]]*help*::
+The *help* command displays a summary of the commands and their arguments.
+
+== SEE ALSO
+
+<<chrony.conf.adoc#,*chrony.conf(5)*>>, <<chronyd.adoc#,*chronyd(8)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony-project.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chronyc.man.in b/doc/chronyc.man.in
new file mode 100644
index 0000000..55a05b7
--- /dev/null
+++ b/doc/chronyc.man.in
@@ -0,0 +1,2752 @@
+'\" t
+.\"     Title: chronyc
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.20
+.\"      Date: 2023-08-09
+.\"    Manual: User manual
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONYC" "1" "2023-08-09" "chrony @CHRONY_VERSION@" "User manual"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chronyc \- command\-line interface for chrony daemon
+.SH "SYNOPSIS"
+.sp
+\fBchronyc\fP [\fIOPTION\fP]... [\fICOMMAND\fP]...
+.SH "DESCRIPTION"
+.sp
+\fBchronyc\fP is a command\-line interface program which can be used to monitor
+\fBchronyd\fP\*(Aqs performance and to change various operating parameters whilst it is
+running.
+.sp
+If no commands are specified on the command line, \fBchronyc\fP will expect input
+from the user. The prompt \fIchronyc>\fP will be displayed when it is being run
+from a terminal. If \fBchronyc\fP\*(Aqs input or output are redirected from or to a file,
+the prompt will not be shown.
+.sp
+There are two ways \fBchronyc\fP can access \fBchronyd\fP. One is the Internet
+Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is
+accessible locally by the root or \fIchrony\fP user. By default, \fBchronyc\fP first
+tries to connect to the Unix domain socket. The compiled\-in default path is
+\fI@CHRONYRUNDIR@/chronyd.sock\fP. If that fails (e.g. because \fBchronyc\fP is
+running under a non\-root user), it will try to connect to 127.0.0.1 and then
+::1.
+.sp
+Only the following monitoring commands, which do not affect the behaviour of
+\fBchronyd\fP, are allowed from the network: \fBactivity\fP, \fBmanual list\fP,
+\fBrtcdata\fP, \fBsmoothing\fP, \fBsourcename\fP, \fBsources\fP, \fBsourcestats\fP, \fBtracking\fP,
+\fBwaitsync\fP. The
+set of hosts from which \fBchronyd\fP will accept these commands can be configured
+with the \fBcmdallow\fP directive in the \fBchronyd\fP\*(Aqs
+configuration file or the \fBcmdallow\fP command in \fBchronyc\fP. By
+default, the commands are accepted only from localhost (127.0.0.1 or ::1).
+.sp
+All other commands are allowed only through the Unix domain socket. When sent
+over the network, \fBchronyd\fP will respond with a \(oqNot authorised\(cq error, even
+if it is from localhost.
+.sp
+Having full access to \fBchronyd\fP via \fBchronyc\fP is more or less equivalent to
+being able to modify the \fBchronyd\fP\*(Aqs configuration file and restart it.
+.SH "OPTIONS"
+.sp
+\fB\-4\fP
+.RS 4
+With this option hostnames will be resolved only to IPv4 addresses.
+.RE
+.sp
+\fB\-6\fP
+.RS 4
+With this option hostnames will be resolved only to IPv6 addresses.
+.RE
+.sp
+\fB\-n\fP
+.RS 4
+This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
+DNS lookups. Long addresses will not be truncated to fit into the column.
+.RE
+.sp
+\fB\-N\fP
+.RS 4
+This option enables printing of original hostnames or IP addresses of NTP
+sources that were specified in the configuration file, or \fBchronyc\fP commands.
+Without the \fB\-n\fP and \fB\-N\fP option, the printed hostnames are obtained from
+reverse DNS lookups and can be different from the specified hostnames.
+.RE
+.sp
+\fB\-c\fP
+.RS 4
+This option enables printing of reports in a comma\-separated values (CSV)
+format. Reverse DNS lookups will be disabled, time will be printed as number of
+seconds since the epoch, and values in seconds will not be converted to other
+units.
+.RE
+.sp
+\fB\-e\fP
+.RS 4
+With this option each \fBchronyc\fP response will end with a line containing a
+single dot.
+.RE
+.sp
+\fB\-d\fP
+.RS 4
+This option enables printing of debugging messages if \fBchronyc\fP was compiled
+with debugging support.
+.RE
+.sp
+\fB\-m\fP
+.RS 4
+Normally, all arguments on the command line are interpreted as one command.
+With this option multiple commands can be specified. Each argument will be
+interpreted as a whole command.
+.RE
+.sp
+\fB\-h\fP \fIhost\fP
+.RS 4
+This option specifies the host to be contacted by \fBchronyc\fP. It can be
+specified with a hostname, IP address, or path to the local Unix domain socket.
+Multiple values can be specified as a comma\-separated list to provide a
+fallback.
+.sp
+The default value is \fI@CHRONYRUNDIR@/chronyd.sock,127.0.0.1,::1\fP, i.e. the host
+where \fBchronyc\fP is being run. First, it tries to connect to the Unix domain
+socket and if that fails (e.g. due to running under a non\-root user), it
+will try to connect to 127.0.0.1 and then ::1.
+.RE
+.sp
+\fB\-p\fP \fIport\fP
+.RS 4
+This option allows the user to specify the UDP port number which the target
+\fBchronyd\fP is using for its monitoring connections. This defaults to 323; there
+would rarely be a need to change this.
+.RE
+.sp
+\fB\-f\fP \fIfile\fP
+.RS 4
+This option is ignored and is provided only for compatibility.
+.RE
+.sp
+\fB\-a\fP
+.RS 4
+This option is ignored and is provided only for compatibility.
+.RE
+.sp
+\fB\-v\fP, \fB\-\-version\fP
+.RS 4
+With this option \fBchronyc\fP displays its version number on the terminal and
+exits.
+.RE
+.sp
+\fB\-\-help\fP
+.RS 4
+With this option \fBchronyc\fP displays a help message on the terminal and
+exits.
+.RE
+.SH "COMMANDS"
+.sp
+This section describes each of the commands available within the \fBchronyc\fP
+program.
+.SS "System clock"
+.sp
+\fBtracking\fP
+.RS 4
+The \fBtracking\fP command displays parameters about the system\(cqs clock
+performance. An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Reference ID    : CB00710F (foo.example.net)
+Stratum         : 3
+Ref time (UTC)  : Fri Jan 27 09:49:17 2017
+System time     : 0.000006523 seconds slow of NTP time
+Last offset     : \-0.000006747 seconds
+RMS offset      : 0.000035822 seconds
+Frequency       : 3.225 ppm slow
+Residual freq   : \-0.000 ppm
+Skew            : 0.129 ppm
+Root delay      : 0.013639022 seconds
+Root dispersion : 0.001100737 seconds
+Update interval : 64.2 seconds
+Leap status     : Normal
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBReference ID\fP
+.RS 4
+This is the reference ID and name (or IP address) of the server to which the
+computer is currently synchronised. For IPv4 addresses, the reference ID is
+equal to the address and for IPv6 addresses it is the first 32 bits of the MD5
+sum of the address.
+.sp
+If the reference ID is \fI7F7F0101\fP and there is no name or IP address, it means
+the computer is not synchronised to any external source and that you have the
+\fIlocal\fP mode operating (via the \fBlocal\fP command in \fBchronyc\fP, or the
+\fBlocal\fP directive in the configuration file).
+.sp
+The reference ID is printed as a hexadecimal number. Note that in older
+versions it used to be printed in quad\-dotted notation and could be confused
+with an IPv4 address.
+.RE
+.sp
+\fBStratum\fP
+.RS 4
+The stratum indicates how many hops away from a computer with an attached
+reference clock we are. Such a computer is a stratum\-1 computer, so the
+computer in the example is two hops away (i.e. \fIfoo.example.net\fP is a
+stratum\-2 and is synchronised from a stratum\-1).
+.RE
+.sp
+\fBRef time\fP
+.RS 4
+This is the time (UTC) at which the last measurement from the reference
+source was processed.
+.RE
+.sp
+\fBSystem time\fP
+.RS 4
+This is the current offset between the NTP clock and system clock. The NTP
+clock is a software (virtual) clock maintained by \fBchronyd\fP, which is
+synchronised to the configured time sources and provides time to NTP clients.
+The system clock is synchronised to the NTP clock. To avoid steps in the
+system time, which might have adverse consequences for certain applications,
+the system clock is normally corrected only by speeding up or slowing down (up
+to the rate configured by the \fBmaxslewrate\fP
+directive). If the offset is too large, this correction will take a very long
+time. A step can be forced by the \fBmakestep\fP command, or the
+\fBmakestep\fP directive in the configuration file.
+.sp
+Note that all other offsets reported by \fBchronyc\fP and most offsets in the log
+files are relative to the NTP clock, not the system clock.
+.RE
+.sp
+\fBLast offset\fP
+.RS 4
+This is the estimated local offset on the last clock update. A positive value
+indicates the local time (as previously estimated true time) was ahead of the
+time sources.
+.RE
+.sp
+\fBRMS offset\fP
+.RS 4
+This is a long\-term average of the offset value.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+The \(oqfrequency\(cq is the rate by which the system\(cqs clock would be wrong if
+\fBchronyd\fP was not correcting it. It is expressed in ppm (parts per million).
+For example, a value of 1 ppm would mean that when the system\(cqs clock thinks it
+has advanced 1 second, it has actually advanced by 1.000001 seconds relative to
+true time.
+.RE
+.sp
+\fBResidual freq\fP
+.RS 4
+This shows the \(oqresidual frequency\(cq for the currently selected reference
+source. This reflects any difference between what the measurements from the
+reference source indicate the frequency should be and the frequency currently
+being used.
+.sp
+The reason this is not always zero is that a smoothing procedure is
+applied to the frequency. Each time a measurement from the reference
+source is obtained and a new residual frequency computed, the estimated
+accuracy of this residual is compared with the estimated accuracy (see
+\(oqskew\(cq next) of the existing frequency value. A weighted average is
+computed for the new frequency, with weights depending on these accuracies.
+If the measurements from the reference source follow a consistent trend, the
+residual will be driven to zero over time.
+.RE
+.sp
+\fBSkew\fP
+.RS 4
+This is the estimated error bound on the frequency.
+.RE
+.sp
+\fBRoot delay\fP
+.RS 4
+This is the total of the network path delays to the stratum\-1 computer from
+which the computer is ultimately synchronised.
+.RE
+.sp
+\fBRoot dispersion\fP
+.RS 4
+This is the total dispersion accumulated through all the computers back to
+the stratum\-1 computer from which the computer is ultimately synchronised.
+Dispersion is due to system clock resolution, statistical measurement
+variations, etc.
+.sp
+An absolute bound on the computer\(cqs clock accuracy (assuming the stratum\-1
+computer is correct) is given by:
+.sp
+.if n .RS 4
+.nf
+.fam C
+clock_error <= |system_time_offset| + root_dispersion + (0.5 * root_delay)
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBUpdate interval\fP
+.RS 4
+This is the interval between the last two clock updates.
+.RE
+.sp
+\fBLeap status\fP
+.RS 4
+This is the leap status, which can be \fINormal\fP, \fIInsert second\fP, \fIDelete
+second\fP or \fINot synchronised\fP.
+.RE
+.RE
+.sp
+\fBmakestep\fP, \fBmakestep\fP \fIthreshold\fP \fIlimit\fP
+.RS 4
+Normally \fBchronyd\fP will cause the system to gradually correct any time offset,
+by slowing down or speeding up the clock as required. In certain situations,
+the system clock might be so far adrift that this slewing process would take a
+very long time to correct the system clock.
+.sp
+The \fBmakestep\fP command can be used in this situation. There are two forms of
+the command. The first form has no parameters. It tells \fBchronyd\fP to cancel any
+remaining correction that was being slewed and jump the system clock by the
+equivalent amount, making it correct immediately.
+.sp
+The second form configures the automatic stepping, similarly to the
+\fBmakestep\fP directive. It has two parameters,
+stepping threshold (in seconds) and number of future clock updates for which
+the threshold will be active. This can be used with the \fBburst\fP
+command to quickly make a new measurement and correct the clock by stepping if
+needed, without waiting for \fBchronyd\fP to complete the measurement and update
+the clock.
+.sp
+.if n .RS 4
+.nf
+.fam C
+makestep 0.1 1
+burst 1/2
+.fam
+.fi
+.if n .RE
+.sp
+BE WARNED: Certain software will be seriously affected by such jumps in the
+system time. (That is the reason why \fBchronyd\fP uses slewing normally.)
+.RE
+.sp
+\fBmaxupdateskew\fP \fIskew\-in\-ppm\fP
+.RS 4
+This command has the same effect as the
+\fBmaxupdateskew\fP directive in the
+configuration file.
+.RE
+.sp
+\fBwaitsync\fP [\fImax\-tries\fP [\fImax\-correction\fP [\fImax\-skew\fP [\fIinterval\fP]]]]
+.RS 4
+The \fBwaitsync\fP command waits for \fBchronyd\fP to synchronise.
+.sp
+Up to four optional arguments can be specified. The first is the maximum number
+of tries before giving up and returning a non\-zero error code. When 0 is
+specified, or there are no arguments, the number of tries will not be limited.
+.sp
+The second and third arguments are the maximum allowed remaining correction of
+the system clock and the maximum allowed skew (in ppm) as reported by the
+\fBtracking\fP command in the \fBSystem time\fP and \fBSkew\fP fields. If not
+specified or zero, the value will not be checked.
+.sp
+The fourth argument is the interval specified in seconds in which the check is
+repeated. The interval is 10 seconds by default.
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+waitsync 60 0.01
+.fam
+.fi
+.if n .RE
+.sp
+which will wait up to about 10 minutes (60 times 10 seconds) for \fBchronyd\fP to
+synchronise to a source and the remaining correction to be less than 10
+milliseconds.
+.RE
+.SS "Time sources"
+.sp
+\fBsources\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+This command displays information about the current time sources that \fBchronyd\fP
+is accessing.
+.sp
+If the \fB\-a\fP option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+\fIID#XXXXXXXXXX\fP, which can be used in other commands expecting a source address.
+.sp
+The \fB\-v\fP option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
+.sp
+.if n .RS 4
+.nf
+.fam C
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+#* GPS0                          0   4   377    11   \-479ns[ \-621ns] +/\-  134ns
+^? foo.example.net               2   6   377    23   \-923us[ \-924us] +/\-   43ms
+^+ bar.example.net               1   6   377    21  \-2629us[\-2619us] +/\-   86ms
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBM\fP
+.RS 4
+This indicates the mode of the source. \fI^\fP means a server, \fI=\fP means a peer
+and \fI#\fP indicates a locally connected reference clock.
+.RE
+.sp
+\fBS\fP
+.RS 4
+This column indicates the selection state of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP indicates the best source which is currently selected for
+synchronisation.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP indicates other sources selected for synchronisation, which are combined
+with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI\-\fP indicates a source which is considered to be selectable for
+synchronisation, but not currently selected.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP indicates a source which \fBchronyd\fP thinks is a falseticker (i.e. its
+time is inconsistent with a majority of other sources, or sources specified
+with the \fBtrust\fP option).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP indicates a source whose time appears to have too much variability.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI?\fP indicates a source which is not considered to be selectable for
+synchronisation for other reasons (e.g. unreachable, not synchronised, or
+does not have enough measurements).
+.RE
+.RE
+.sp
+
+.RS 4
+The \fBselectdata\fP command can be used to get more details about
+the selection state.
+.RE
+.sp
+\fBName/IP address\fP
+.RS 4
+This shows the name or the IP address of the source, or reference ID for reference
+clocks.
+.RE
+.sp
+\fBStratum\fP
+.RS 4
+This shows the stratum of the source, as reported in its most recently
+received sample. Stratum 1 indicates a computer with a locally attached
+reference clock. A computer that is synchronised to a stratum 1 computer is
+at stratum 2. A computer that is synchronised to a stratum 2 computer is at
+stratum 3, and so on.
+.RE
+.sp
+\fBPoll\fP
+.RS 4
+This shows the rate at which the source is being polled, as a base\-2
+logarithm of the interval in seconds. Thus, a value of 6 would indicate that
+a measurement is being made every 64 seconds. \fBchronyd\fP automatically varies
+the polling rate in response to prevailing conditions.
+.RE
+.sp
+\fBReach\fP
+.RS 4
+This shows the source\(cqs reachability register printed as an octal number. The
+register has 8 bits and is updated on every received or missed packet from
+the source. A value of 377 indicates that a valid reply was received for all
+from the last eight transmissions.
+.RE
+.sp
+\fBLastRx\fP
+.RS 4
+This column shows how long ago the last good sample (which is shown in the next
+column) was received from the source. Measurements that failed some tests are
+ignored. This is normally in seconds. The letters \fIm\fP, \fIh\fP, \fId\fP or \fIy\fP indicate
+minutes, hours, days, or years.
+.RE
+.sp
+\fBLast sample\fP
+.RS 4
+This column shows the offset between the local clock and the source at the
+last measurement. The number in the square brackets shows the actual measured
+offset. This can be suffixed by \fIns\fP (indicating nanoseconds), \fIus\fP
+(indicating microseconds), \fIms\fP (indicating milliseconds), or \fIs\fP (indicating
+seconds). The number to the left of the square brackets shows the original
+measurement, adjusted to allow for any slews applied to the local clock
+since. Positive offsets indicate that the local clock is ahead of the source.
+The number following the \fI+/\-\fP indicator shows the margin of error in the
+measurement (NTP root distance).
+.RE
+.RE
+.sp
+\fBsourcestats\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+The \fBsourcestats\fP command displays information about the drift rate and offset
+estimation process for each of the sources currently being examined by
+\fBchronyd\fP.
+.sp
+If the \fB\-a\fP option is specified, all sources are displayed, including those that
+do not have a known address yet. Such sources have an identifier in the format
+\fIID#XXXXXXXXXX\fP, which can be used in other commands expecting a source address.
+.sp
+The \fB\-v\fP option enables a verbose output. In this case,
+extra caption lines are shown as a reminder of the meanings of the columns.
+.sp
+An example report is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+===============================================================================
+foo.example.net            11   5   46m     \-0.001      0.045      1us    25us
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBName/IP Address\fP
+.RS 4
+This is the name or IP address of the NTP server (or peer) or reference ID of the
+reference clock to which the rest of the line relates.
+.RE
+.sp
+\fBNP\fP
+.RS 4
+This is the number of sample points currently being retained for the server.
+The drift rate and current offset are estimated by performing a linear
+regression through these points.
+.RE
+.sp
+\fBNR\fP
+.RS 4
+This is the number of runs of residuals having the same sign following the
+last regression. If this number starts to become too small relative to the
+number of samples, it indicates that a straight line is no longer a good fit
+to the data. If the number of runs is too low, \fBchronyd\fP discards older
+samples and re\-runs the regression until the number of runs becomes
+acceptable.
+.RE
+.sp
+\fBSpan\fP
+.RS 4
+This is the interval between the oldest and newest samples. If no unit is
+shown the value is in seconds. In the example, the interval is 46 minutes.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+This is the estimated residual frequency for the server, in parts per
+million. In this case, the computer\(cqs clock is estimated to be running 1 part
+in 10^9 slow relative to the server.
+.RE
+.sp
+\fBFreq Skew\fP
+.RS 4
+This is the estimated error bounds on \fBFreq\fP (again in parts per million).
+.RE
+.sp
+\fBOffset\fP
+.RS 4
+This is the estimated offset of the source.
+.RE
+.sp
+\fBStd Dev\fP
+.RS 4
+This is the estimated sample standard deviation.
+.RE
+.RE
+.sp
+\fBselectdata\fP [\fB\-a\fP] [\fB\-v\fP]
+.RS 4
+The \fBselectdata\fP command displays information specific to the selection of time
+sources. If the \fB\-a\fP option is specified, all sources are displayed, including
+those that do not have a known address yet. With the \fB\-v\fP option, extra caption
+lines are shown as a reminder of the meanings of the columns.
+.sp
+An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+D foo.example.net           Y \-\-\-\-\- \-\-TR\-    4   1.0   \-61ms   +62ms  N
+* bar.example.net           N \-\-\-\-\- \-\-\-\-\-    0   1.0 \-6846us +7305us  N
++ baz.example.net           N \-\-\-\-\- \-\-\-\-\-   10   1.0 \-7381us +7355us  N
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBS\fP
+.RS 4
+This column indicates the state of the source after the last source selection.
+It is similar to the state reported by the \fBsources\fP command, but more
+states are reported.
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is not considered selectable for
+synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP \- has the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIs\fP \- is not synchronised.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIM\fP \- does not have enough measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fId\fP \- has a root distance larger than the maximum distance (configured by the
+\fBmaxdistance\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI~\fP \- has a jitter larger than the maximum jitter (configured by the
+\fBmaxjitter\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIw\fP \- waits for other sources to get out of the \fIM\fP state.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIS\fP \- has older measurements than other sources.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIO\fP \- has a stratum equal or larger than the orphan stratum (configured by
+the \fBlocal\fP directive).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP \- does not fully agree with sources that have the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIx\fP \- does not agree with other sources (falseticker).
+.RE
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is considered selectable, but it is
+not currently used for synchronisation:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIW\fP \- waits for other sources to be selectable (required by the
+\fBminsources\fP directive, or
+the \fBrequire\fP option of another source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP \- another selectable source is preferred due to the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIU\fP \- waits for a new measurement (after selecting a different best source).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fID\fP \- has, or recently had, a root distance which is too large to be combined
+with other sources (configured by the
+\fBcombinelimit\fP directive).
+.RE
+.RE
+.sp
+
+.RS 4
+The following states indicate the source is used for synchronisation of the
+local clock:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP \- combined with the best source.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI*\fP \- selected as the best source to update the reference data (e.g. root
+delay, root dispersion).
+.RE
+.RE
+.sp
+\fBName/IP address\fP
+.RS 4
+This column shows the name or IP address of the source if it is an NTP server,
+or the reference ID if it is a reference clock.
+.RE
+.sp
+\fBAuth\fP
+.RS 4
+This column indicites whether an authentication mechanism is enabled for the
+source. \fIY\fP means yes and \fIN\fP means no.
+.RE
+.sp
+\fBCOpts\fP
+.RS 4
+This column displays the configured selection options of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP indicates the \fBnoselect\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIP\fP indicates the \fBprefer\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIT\fP indicates the \fBtrust\fP option.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIR\fP indicates the \fBrequire\fP option.
+.RE
+.RE
+.sp
+\fBEOpts\fP
+.RS 4
+This column displays the current effective selection options of the source,
+which can be different from the configured options due to the authentication
+selection mode (configured by the
+\fBauthselectmode\fP directive). The symbols
+are the same as in the \fBCOpts\fP column.
+.RE
+.sp
+\fBLast\fP
+.RS 4
+This column displays how long ago was the last measurement of the source made
+when the selection was performed.
+.RE
+.sp
+\fBScore\fP
+.RS 4
+This column displays the current score against the source in the \fI*\fP state. The
+scoring system avoids frequent reselection when multiple sources have a similar
+root distance. A value larger than 1 indicates this source was better than the
+\fI*\fP source in recent selections. If the score reaches 10, the best source will
+be reselected and the scores will be reset to 1.
+.RE
+.sp
+\fBInterval\fP
+.RS 4
+This column displays the lower and upper endpoint of the interval which was
+expected to contain the true offset of the local clock considering the root
+distance at the time of the selection.
+.RE
+.sp
+\fBLeap\fP
+.RS 4
+This column displays the current leap status of the source.
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fIN\fP indicates the normal status (no leap second).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI+\fP indicates that a leap second will be inserted at the end of the month.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI\-\fP indicates that a leap second will be deleted at the end of the month.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+\fI?\fP indicates the unknown status (i.e. no valid measurement was made).
+.RE
+.RE
+.RE
+.sp
+\fBselectopts\fP \fIaddress|refid\fP [\fI+|\-option\fP]...
+.RS 4
+The \fBselectopts\fP command modifies the configured selection options of an NTP
+source specified by IP address (or the \fIID#XXXXXXXXXX\fP identifier used for
+unknown addresses), or a reference clock specified by reference ID as a string.
+.sp
+The selection options can be added with the \fB+\fP symbol or removed with the \fB\-\fP
+symbol. The \fBselectdata\fP command can be used to verify the configuration. The
+modified options will be applied in the next source selection, e.g. when a new
+measurement is made, or the \fBreselect\fP command is executed.
+.sp
+An example of using this command is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+selectopts 1.2.3.4 \-noselect +prefer
+selectopts GPS +trust
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBreselect\fP
+.RS 4
+To avoid excessive switching between sources, \fBchronyd\fP can stay synchronised
+to a source even when it is not currently the best one among the available
+sources.
+.sp
+The \fBreselect\fP command can be used to force \fBchronyd\fP to reselect the best
+synchronisation source.
+.RE
+.sp
+\fBreselectdist\fP \fIdistance\fP
+.RS 4
+The \fBreselectdist\fP command sets the reselection distance. It is equivalent to
+the \fBreselectdist\fP directive in the
+configuration file.
+.RE
+.SS "NTP sources"
+.sp
+\fBactivity\fP
+.RS 4
+This command reports the number of servers and peers that are online and
+offline. If the \fBauto_offline\fP option is used in specifying some of the servers
+or peers, the \fBactivity\fP command can be useful for detecting when all of them
+have entered the offline state after the network link has been disconnected.
+.sp
+The report shows the number of servers and peers in 5 states:
+.sp
+\fBonline\fP
+.RS 4
+the server or peer is currently online (i.e. assumed by \fBchronyd\fP to be reachable)
+.RE
+.sp
+\fBoffline\fP
+.RS 4
+the server or peer is currently offline (i.e. assumed by \fBchronyd\fP to be
+unreachable, and no measurements from it will be attempted.)
+.RE
+.sp
+\fBburst_online\fP
+.RS 4
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the online state.
+.RE
+.sp
+\fBburst_offline\fP
+.RS 4
+a burst command has been initiated for the server or peer and is being
+performed; after the burst is complete, the server or peer will be returned to
+the offline state.
+.RE
+.sp
+\fBunresolved\fP
+.RS 4
+the name of the server or peer was not resolved to an address yet; this source is
+not visible in the \fBsources\fP and \fBsourcestats\fP reports.
+.RE
+.RE
+.sp
+\fBauthdata\fP [\fB\-a\fP]
+.RS 4
+The \fBauthdata\fP command displays information specific to authentication of NTP
+sources. If the \fB\-a\fP option is specified, all sources are displayed, including
+those that do not have a known address yet. An example of the output is
+shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256 135m    0    0    8  100
+bar.example.net               SK    30   13  128    \-    0    0    0    0
+baz.example.net                \-     0    0    0    \-    0    0    0    0
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as follows:
+.sp
+\fBName/IP address\fP
+.RS 4
+This column shows the name or the IP address of the source.
+.RE
+.sp
+\fBMode\fP
+.RS 4
+This column shows which mechanism authenticates NTP packets received from the
+source. \fINTS\fP means Network Time Security, \fISK\fP means a symmetric key, and \fI\-\fP
+means authentication is disabled.
+.RE
+.sp
+\fBKeyID\fP
+.RS 4
+This column shows an identifier of the key used for authentication. With a
+symmetric key, it is the ID from the key file.
+With NTS, it is a number starting at zero and incremented by one with each
+successful key establishment using the NTS\-KE protocol, i.e. it shows how many
+times the key establishment was performed with this source.
+.RE
+.sp
+\fBType\fP
+.RS 4
+This columns shows an identifier of the algorithm used for authentication.
+With a symmetric key, it is the hash function or cipher specified in the key
+file. With NTS, it is an authenticated encryption with associated data (AEAD)
+algorithm, which is negotiated in the NTS\-KE protocol. The following values can
+be reported:
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+1: MD5
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+2: SHA1
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+3: SHA256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+4: SHA384
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+5: SHA512
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+6: SHA3\-224
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+7: SHA3\-256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+8: SHA3\-384
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+9: SHA3\-512
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+10: TIGER
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+11: WHIRLPOOL
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+13: AES128
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+14: AES256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+15: AEAD\-AES\-SIV\-CMAC\-256
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04'\(bu\h'+03'\c
+.\}
+.el \{\
+.  sp -1
+.  IP \(bu 2.3
+.\}
+30: AEAD\-AES\-128\-GCM\-SIV
+.RE
+.RE
+.sp
+\fBKLen\fP
+.RS 4
+This column shows the length of the key in bits.
+.RE
+.sp
+\fBLast\fP
+.RS 4
+This column shows how long ago the last successful key establishment was
+performed. It is in seconds, or letters \fIm\fP, \fIh\fP, \fId\fP or \fIy\fP indicate minutes,
+hours, days, or years.
+.RE
+.sp
+\fBAtmp\fP
+.RS 4
+This column shows the number of attempts to perform the key establishment since
+the last successful key establishment. A number larger than 1 indicates a
+problem with the network or server.
+.RE
+.sp
+\fBNAK\fP
+.RS 4
+This column shows whether an NTS NAK was received since the last request.
+A NAK indicates that authentication failed on the server side due to
+\fBchronyd\fP using a cookie which is no longer valid and that it needs to perform
+the key establishment again in order to get new cookies.
+.RE
+.sp
+\fBCook\fP
+.RS 4
+This column shows the number of NTS cookies that \fBchronyd\fP currently has. If
+the key establishment was successful, a number smaller than 8 indicates a
+problem with the network or server.
+.RE
+.sp
+\fBCLen\fP
+.RS 4
+This column shows the length in bytes of the NTS cookie which will be used in
+the next request.
+.RE
+.RE
+.sp
+\fBntpdata\fP [\fIaddress\fP]
+.RS 4
+The \fBntpdata\fP command displays the last valid measurement and other
+NTP\-specific information about the specified NTP source, or all NTP sources
+(with a known address) if no address was specified. An example of the output is
+shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Remote address  : 203.0.113.15 (CB00710F)
+Remote port     : 123
+Local address   : 203.0.113.74 (CB00714A)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 10 (1024 seconds)
+Precision       : \-24 (0.000000060 seconds)
+Root delay      : 0.000015 seconds
+Root dispersion : 0.000015 seconds
+Reference ID    : 47505300 (GPS)
+Reference time  : Fri Nov 25 15:22:12 2016
+Offset          : \-0.000060878 seconds
+Peer delay      : 0.000175634 seconds
+Peer dispersion : 0.000000681 seconds
+Response time   : 0.000053050 seconds
+Jitter asymmetry: +0.00
+NTP tests       : 111 111 1111
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 24
+Total RX        : 24
+Total valid RX  : 24
+Total good RX   : 22
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBRemote address\fP
+.RS 4
+The IP address of the NTP server or peer, and the corresponding reference ID.
+.RE
+.sp
+\fBRemote port\fP
+.RS 4
+The UDP port number to which the request was sent. The standard NTP port is
+123.
+.RE
+.sp
+\fBLocal address\fP
+.RS 4
+The local IP address which received the response, and the corresponding
+reference ID.
+.RE
+.sp
+\fBLeap status\fP, \fBVersion\fP, \fBMode\fP, \fBStratum\fP, \fBPoll interval\fP, \fBPrecision\fP, \fBRoot delay\fP, \fBRoot dispersion\fP, \fBReference ID\fP, \fBReference time\fP
+.RS 4
+The NTP values from the last valid response.
+.RE
+.sp
+\fBOffset\fP, \fBPeer delay\fP, \fBPeer dispersion\fP
+.RS 4
+The measured values.
+.RE
+.sp
+\fBResponse time\fP
+.RS 4
+The time the server or peer spent in processing of the request and waiting
+before sending the response.
+.RE
+.sp
+\fBJitter asymmetry\fP
+.RS 4
+The estimated asymmetry of network jitter on the path to the source. The
+asymmetry can be between \-0.5 and 0.5. A negative value means the delay of
+packets sent to the source is more variable than the delay of packets sent
+from the source back.
+.RE
+.sp
+\fBNTP tests\fP
+.RS 4
+Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum
+delay, delay ratio, delay dev ratio (or delay quantile), and synchronisation
+loop.
+.RE
+.sp
+\fBInterleaved\fP
+.RS 4
+This shows if the response was in the interleaved mode.
+.RE
+.sp
+\fBAuthenticated\fP
+.RS 4
+This shows if the response was authenticated.
+.RE
+.sp
+\fBTX timestamping\fP
+.RS 4
+The source of the local transmit timestamp. Valid values are \fIDaemon\fP,
+\fIKernel\fP, and \fIHardware\fP.
+.RE
+.sp
+\fBRX timestamping\fP
+.RS 4
+The source of the local receive timestamp.
+.RE
+.sp
+\fBTotal TX\fP
+.RS 4
+The number of packets sent to the source.
+.RE
+.sp
+\fBTotal RX\fP
+.RS 4
+The number of all packets received from the source.
+.RE
+.sp
+\fBTotal valid RX\fP
+.RS 4
+The number of packets which passed the first two groups of NTP tests.
+.RE
+.sp
+\fBTotal good RX\fP
+.RS 4
+The number of packets which passed all three groups of NTP tests, i.e. the NTP
+measurement was accepted.
+.RE
+.RE
+.sp
+\fBadd peer\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd peer\fP command allows a new NTP peer to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd peer\fP, the syntax of the following
+parameters and options is identical to that for the
+\fBpeer\fP directive in the configuration file.
+.sp
+An example of using this command is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+add peer foo.example.net minpoll 6 maxpoll 10 key 25
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBadd pool\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd pool\fP command allows a pool of NTP servers to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd pool\fP, the syntax of the following parameters and
+options is identical to that for the \fBpool\fP
+directive in the configuration file.
+.sp
+An example of using this command is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+add pool foo.example.net maxsources 3 iburst
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBadd server\fP \fIname\fP [\fIoption\fP]...
+.RS 4
+The \fBadd server\fP command allows a new NTP server to be added whilst
+\fBchronyd\fP is running.
+.sp
+Following the words \fBadd server\fP, the syntax of the following parameters and
+options is identical to that for the \fBserver\fP
+directive in the configuration file.
+.sp
+An example of using this command is shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+add server foo.example.net minpoll 6 maxpoll 10 key 25
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdelete\fP \fIaddress\fP
+.RS 4
+The \fBdelete\fP command allows an NTP server or peer to be removed
+from the current set of sources.
+.RE
+.sp
+\fBburst\fP \fIgood\fP/\fImax\fP [\fImask\fP/\fImasked\-address\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBburst\fP \fIgood\fP/\fImax\fP [\fIaddress\fP]
+.RS 4
+The \fBburst\fP command tells \fBchronyd\fP to make a set of measurements to each of
+its NTP sources over a short duration (rather than the usual periodic
+measurements that it makes). After such a burst, \fBchronyd\fP will revert to the
+previous state for each source. This might be either online, if the source was
+being periodically measured in the normal way, or offline, if the source had
+been indicated as being offline. (A source can be switched between the online
+and offline states with the \fBonline\fP and \fBoffline\fP
+commands.)
+.sp
+The \fImask\fP and \fImasked\-address\fP arguments are optional, in which case \fBchronyd\fP
+will initiate a burst for all of its currently defined sources.
+.sp
+The arguments have the following meaning and format:
+.sp
+\fIgood\fP
+.RS 4
+This defines the number of good measurements that \fBchronyd\fP will want to
+obtain from each source. A measurement is good if it passes certain tests,
+for example, the round trip time to the source must be acceptable. (This
+allows \fBchronyd\fP to reject measurements that are likely to be bogus.)
+.RE
+.sp
+\fImax\fP
+.RS 4
+This defines the maximum number of measurements that \fBchronyd\fP will attempt
+to make, even if the required number of good measurements has not been
+obtained.
+.RE
+.sp
+\fImask\fP
+.RS 4
+This is an IP address with which the IP address of each of \fBchronyd\fP\*(Aqs
+sources is to be masked.
+.RE
+.sp
+\fImasked\-address\fP
+.RS 4
+This is an IP address. If the masked IP address of a source matches this
+value then the burst command is applied to that source.
+.RE
+.sp
+\fImasked\-bits\fP
+.RS 4
+This can be used with \fImasked\-address\fP for CIDR notation, which is a shorter
+alternative to the form with mask.
+.RE
+.sp
+\fIaddress\fP
+.RS 4
+This is an IP address or a hostname. The burst command is applied only to
+that source.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+If no \fImask\fP or \fImasked\-address\fP arguments are provided, every source will be
+matched.
+.sp
+An example of the two\-argument form of the command is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10
+.fam
+.fi
+.if n .RE
+.sp
+This will cause \fBchronyd\fP to attempt to get two good measurements from each
+source, stopping after two have been obtained, but in no event will it try more
+than ten probes to the source.
+.sp
+Examples of the four\-argument form of the command are:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10 255.255.0.0/1.2.0.0
+burst 2/10 2001:db8:789a::/48
+.fam
+.fi
+.if n .RE
+.sp
+In the first case, the two out of ten sampling will only be applied to sources
+whose IPv4 addresses are of the form \fI1.2.x.y\fP, where \fIx\fP and \fIy\fP are
+arbitrary. In the second case, the sampling will be applied to sources whose
+IPv6 addresses have first 48 bits equal to \fI2001:db8:789a\fP.
+.sp
+Example of the three\-argument form of the command is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+burst 2/10 foo.example.net
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBmaxdelay\fP \fIaddress\fP \fIdelay\fP
+.RS 4
+This allows the \fBmaxdelay\fP option for one of the sources to be modified, in the
+same way as specifying the \fBmaxdelay\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxdelaydevratio\fP \fIaddress\fP \fIratio\fP
+.RS 4
+This allows the \fBmaxdelaydevratio\fP option for one of the sources to be
+modified, in the same way as specifying the \fBmaxdelaydevratio\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxdelayratio\fP \fIaddress\fP \fIratio\fP
+.RS 4
+This allows the \fBmaxdelayratio\fP option for one of the sources to be modified,
+in the same way as specifying the \fBmaxdelayratio\fP option for the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBmaxpoll\fP \fIaddress\fP \fImaxpoll\fP
+.RS 4
+The \fBmaxpoll\fP command is used to modify the maximum polling interval for one of
+the current set of sources. It is equivalent to the \fBmaxpoll\fP option in the
+\fBserver\fP directive in the configuration file.
+.sp
+Note that the new maximum polling interval only takes effect after the next
+measurement has been made.
+.RE
+.sp
+\fBminpoll\fP \fIaddress\fP \fIminpoll\fP
+.RS 4
+The \fBminpoll\fP command is used to modify the minimum polling interval for one of
+the current set of sources. It is equivalent to the \fBminpoll\fP option in the
+\fBserver\fP directive in the configuration file.
+.sp
+Note that the new minimum polling interval only takes effect after the next
+measurement has been made.
+.RE
+.sp
+\fBminstratum\fP \fIaddress\fP \fIminstratum\fP
+.RS 4
+The \fBminstratum\fP command is used to modify the minimum stratum for one of the
+current set of sources. It is equivalent to the \fBminstratum\fP option in the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBoffline\fP [\fIaddress\fP], \fBoffline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBoffline\fP [\fImask\fP/\fImasked\-address\fP]
+.RS 4
+The \fBoffline\fP command is used to warn \fBchronyd\fP that the network connection to
+a particular host or hosts is about to be lost, e.g. on computers with
+intermittent connection to their time sources.
+.sp
+Another case where \fBoffline\fP could be used is where a computer serves time to a
+local group of computers, and has a permanent connection to true time servers
+outside the organisation. However, the external connection is heavily loaded at
+certain times of the day and the measurements obtained are less reliable at
+those times. In this case, it is probably most useful to determine the
+gain or loss rate during the quiet periods and let the whole network coast through
+the loaded periods. The \fBoffline\fP and \fBonline\fP commands can be used to achieve
+this.
+.sp
+There are four forms of the \fBoffline\fP command. The first form is a wildcard,
+meaning all sources (including sources that do not have a known address yet).
+The second form allows an IP address mask and a masked
+address to be specified. The third form uses CIDR notation. The fourth form
+uses an IP address or a hostname. These forms are illustrated below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+offline
+offline 255.255.255.0/1.2.3.0
+offline 2001:db8:789a::/48
+offline foo.example.net
+.fam
+.fi
+.if n .RE
+.sp
+The second form means that the \fBoffline\fP command is to be applied to any source
+whose IPv4 address is in the \fI1.2.3\fP subnet. (The host\(cqs address is logically
+and\-ed with the mask, and if the result matches the \fImasked\-address\fP the host
+is processed.) The third form means that the command is to be applied to all
+sources whose IPv6 addresses have their first 48 bits equal to \fI2001:db8:789a\fP. The
+fourth form means that the command is to be applied only to that one source.
+.sp
+The wildcard form of the address is equivalent to:
+.sp
+.if n .RS 4
+.nf
+.fam C
+offline 0.0.0.0/0.0.0.0
+offline ::/0
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBonline\fP [\fIaddress\fP], \fBonline\fP [\fImasked\-address\fP/\fImasked\-bits\fP], \fBonline\fP [\fImask\fP/\fImasked\-address\fP]
+.RS 4
+The \fBonline\fP command is opposite in function to the \fBoffline\fP
+command. It is used to advise \fBchronyd\fP that network connectivity to a
+particular source or sources has been restored.
+.sp
+The syntax is identical to that of the \fBoffline\fP command.
+.RE
+.sp
+\fBonoffline\fP
+.RS 4
+The \fBonoffline\fP command tells \fBchronyd\fP to switch all sources that have a known
+address to the online or
+offline status according to the current network configuration. A source is
+considered online if it is possible to send requests to it, i.e. a network
+route to the source is present.
+.RE
+.sp
+\fBpolltarget\fP \fIaddress\fP \fIpolltarget\fP
+.RS 4
+The \fBpolltarget\fP command is used to modify the poll target for one of the
+current set of sources. It is equivalent to the \fBpolltarget\fP option in the
+\fBserver\fP directive in the configuration file.
+.RE
+.sp
+\fBrefresh\fP
+.RS 4
+The \fBrefresh\fP command can be used to force \fBchronyd\fP to resolve the names of
+configured NTP sources to IP addresses again and replace any addresses missing
+in the list of resolved addresses.
+.sp
+Sources that stop responding are replaced with newly resolved addresses
+automatically after 8 polling intervals. This command can be used to replace
+them immediately, e.g. after suspending and resuming the machine in a different
+network.
+.sp
+Note that with pools which have more than 16 addresses, or not all IPv4 or IPv6
+addresses are included in a single DNS response (e.g. pool.ntp.org), this
+command might replace the addresses even if they are still in the pool.
+.RE
+.sp
+\fBreload\fP \fBsources\fP
+.RS 4
+The \fBreload sources\fP command causes \fBchronyd\fP to re\-read all \fI*.sources\fP files
+from the directories specified by the
+\fBsourcedir\fP directive.
+.RE
+.sp
+\fBsourcename\fP \fIaddress\fP
+.RS 4
+The \fBsourcename\fP command prints the original hostname or address that was
+specified for an NTP source in the configuration file, or the \fBadd\fP command.
+This command is an alternative to the \fB\-N\fP option, which can be useful in
+scripts.
+.sp
+Note that different NTP sources can share the same name, e.g. servers from a
+pool.
+.RE
+.SS "Manual time input"
+.sp
+\fBmanual\fP \fBon\fP, \fBmanual\fP \fBoff\fP, \fBmanual\fP \fBdelete\fP \fIindex\fP, \fBmanual\fP \fBlist\fP, \fBmanual\fP \fBreset\fP
+.RS 4
+The manual command enables and disables use of the \fBsettime\fP
+command, and is used to modify the behaviour of the manual clock driver.
+.sp
+The \fBon\fP form of the command enables use of the \fBsettime\fP command.
+.sp
+The \fBoff\fP form of the command disables use of the \fBsettime\fP command.
+.sp
+The \fBlist\fP form of the command lists all the samples currently stored in
+\fBchronyd\fP. The output is illustrated below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+210 n_samples = 1
+#    Date  Time(UTC)    Slewed   Original   Residual
+====================================================
+ 0 27Jan99 22:09:20       0.00       0.97       0.00
+.fam
+.fi
+.if n .RE
+.sp
+The columns are as as follows:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+The sample index (used for the \fBmanual delete\fP command).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The date and time of the sample.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The system clock error when the timestamp was entered, adjusted to allow
+for changes made to the system clock since.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The system clock error when the timestamp was entered, as it originally was
+(without allowing for changes to the system clock since).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The regression residual at this point, in seconds. This allows \(oqoutliers\(cq
+to be easily spotted, so that they can be deleted using the \fBmanual delete\fP
+command.
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+The \fBdelete\fP form of the command deletes a single sample. The parameter is the
+index of the sample, as shown in the first column of the output from \fBmanual
+list\fP. Following deletion of the data point, the current error and drift rate
+are re\-estimated from the remaining data points and the system clock trimmed if
+necessary. This option is intended to allow \(oqoutliers\(cq to be discarded, i.e.
+samples where the administrator realises they have entered a very poor
+timestamp.
+.sp
+The \fBreset\fP form of the command deletes all samples at once. The system clock
+is left running as it was before the command was entered.
+.RE
+.sp
+\fBsettime\fP \fItime\fP
+.RS 4
+The \fBsettime\fP command allows the current time to be entered manually, if this
+option has been configured into \fBchronyd\fP. (It can be configured either with
+the \fBmanual\fP directive in the configuration file,
+or with the \fBmanual\fP command of \fBchronyc\fP.)
+.sp
+It should be noted that the computer\(cqs sense of time will only be as accurate
+as the reference you use for providing this input (e.g. your watch), as well as
+how well you can time the press of the return key.
+.sp
+Providing your computer\(cqs time zone is set up properly, you will be able to
+enter a local time (rather than UTC).
+.sp
+The response to a successful \fBsettime\fP command indicates the amount that the
+computer\(cqs clock was wrong. It should be apparent from this if you have entered
+the time wrongly, e.g. with the wrong time zone.
+.sp
+The rate of drift of the system clock is estimated by a regression process
+using the entered measurement and all previous measurements entered during the
+present run of \fBchronyd\fP. However, the entered measurement is used for
+adjusting the current clock offset (rather than the estimated intercept from
+the regression, which is ignored). Contrast what happens with the
+\fBmanual delete\fP command, where the intercept is used to set the
+current offset (since there is no measurement that has just been entered in
+that case).
+.sp
+The time is parsed by the public domain \fIgetdate\fP algorithm. Consequently, you
+can only specify time to the nearest second.
+.sp
+Examples of inputs that are valid are shown below:
+.sp
+.if n .RS 4
+.nf
+.fam C
+settime 16:30
+settime 16:30:05
+settime Nov 21, 2015 16:30:05
+.fam
+.fi
+.if n .RE
+.sp
+For a full description of getdate, see the getdate documentation
+(bundled, for example, with the source for GNU tar).
+.RE
+.SS "NTP access"
+.sp
+\fBaccheck\fP \fIaddress\fP
+.RS 4
+This command allows you to check whether client NTP access is allowed from a
+particular host.
+.sp
+Examples of use, showing a named host and a numeric IP address, are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+accheck foo.example.net
+accheck 1.2.3.4
+accheck 2001:db8::1
+.fam
+.fi
+.if n .RE
+.sp
+This command can be used to examine the effect of a series of \fBallow\fP, \fBallow
+all\fP, \fBdeny\fP, and \fBdeny all\fP commands specified either via \fBchronyc\fP, or in
+\fBchronyd\fP\*(Aqs configuration file.
+.RE
+.sp
+\fBclients\fP [\fB\-p\fP \fIpackets\fP] [\fB\-k\fP] [\fB\-r\fP]
+.RS 4
+This command shows a list of clients that have accessed the server, through
+the NTP, command, or NTS\-KE port. It does not include accesses over the Unix
+domain command socket.
+.sp
+The \fB\-p\fP option specifies the minimum number of received NTP or command
+packets, or accepted NTS\-KE connections, needed to include a client in the
+list. The default value is 0, i.e. all clients are reported. With the \fB\-k\fP
+option the last four columns will show the NTS\-KE accesses instead of command
+accesses. If the \fB\-r\fP option is specified, \fBchronyd\fP will reset the counters of
+received and dropped packets or connections after reporting the current values.
+.sp
+An example of the output is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+localhost                       2      0   2   \-   133      15      0  \-1     7
+foo.example.net                12      0   6   \-    23       0      0   \-     \-
+.fam
+.fi
+.if n .RE
+.sp
+Each row shows the data for a single host. Only hosts that have passed the host
+access checks (set with the \fBallow\fP, \fBdeny\fP,
+\fBcmdallow\fP and \fBcmddeny\fP commands or configuration
+file directives) are logged. The intervals are displayed as a power of 2 in
+seconds.
+.sp
+The columns are as follows:
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+The hostname of the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+The number of NTP packets received from the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+The number of NTP packets dropped to limit the response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+The average interval between NTP packets.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 5.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 5." 4.2
+.\}
+The average interval between NTP packets after limiting the response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 6.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 6." 4.2
+.\}
+Time since the last NTP packet was received
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 7.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 7." 4.2
+.\}
+The number of command packets or NTS\-KE connections received/accepted from
+the client.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 8.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 8." 4.2
+.\}
+The number of command packets or NTS\-KE connections dropped to limit the
+response rate.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 9.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 9." 4.2
+.\}
+The average interval between command packets or NTS\-KE connections.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 10.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 10." 4.2
+.\}
+Time since the last command packet or NTS\-KE connection was
+received/accepted.
+.RE
+.RE
+.sp
+\fBserverstats\fP
+.RS 4
+The \fBserverstats\fP command displays NTP and command server statistics.
+.sp
+An example of the output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+NTP packets received       : 1598
+NTP packets dropped        : 8
+Command packets received   : 19
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS\-KE connections accepted: 3
+NTS\-KE connections dropped : 0
+Authenticated NTP packets  : 189
+Interleaved NTP packets    : 43
+NTP timestamps held        : 44
+NTP timestamp span         : 120
+NTP daemon RX timestamps   : 0
+NTP daemon TX timestamps   : 1537
+NTP kernel RX timestamps   : 1590
+NTP kernel TX timestamps   : 43
+NTP hardware RX timestamps : 0
+NTP hardware TX timestamps : 0
+.fam
+.fi
+.if n .RE
+.sp
+The fields have the following meaning:
+.sp
+\fBNTP packets received\fP
+.RS 4
+The number of valid NTP requests received by the server.
+.RE
+.sp
+\fBNTP packets dropped\fP
+.RS 4
+The number of NTP requests dropped by the server due to rate limiting
+(configured by the \fBratelimit\fP directive).
+.RE
+.sp
+\fBCommand packets received\fP
+.RS 4
+The number of command requests received by the server.
+.RE
+.sp
+\fBCommand packets dropped\fP
+.RS 4
+The number of command requests dropped by the server due to rate limiting
+(configured by the \fBcmdratelimit\fP directive).
+.RE
+.sp
+\fBClient log records dropped\fP
+.RS 4
+The number of client log records dropped by the server to limit the memory use
+(configured by the \fBclientloglimit\fP
+directive).
+.RE
+.sp
+\fBNTS\-KE connections accepted\fP
+.RS 4
+The number of NTS\-KE connections accepted by the server.
+.RE
+.sp
+\fBNTS\-KE connections dropped\fP
+.RS 4
+The number of NTS\-KE connections dropped by the server due to rate limiting
+(configured by the \fBntsratelimit\fP directive).
+.RE
+.sp
+\fBAuthenticated NTP packets\fP
+.RS 4
+The number of received NTP requests that were authenticated (with a symmetric
+key or NTS).
+.RE
+.sp
+\fBInterleaved NTP packets\fP
+.RS 4
+The number of received NTP requests that were detected to be in the interleaved
+mode.
+.RE
+.sp
+\fBNTP timestamps held\fP
+.RS 4
+The number of pairs of receive and transmit timestamps that the server is
+currently holding in memory for clients using the interleaved mode.
+.RE
+.sp
+\fBNTP timestamp span\fP
+.RS 4
+The interval (in seconds) covered by the currently held NTP timestamps.
+.RE
+.sp
+\fBNTP daemon RX timestamps\fP
+.RS 4
+The number of NTP responses which included a receive timestamp captured by the
+daemon.
+.RE
+.sp
+\fBNTP daemon TX timestamps\fP
+.RS 4
+The number of NTP responses which included a transmit timestamp captured by the
+daemon.
+.RE
+.sp
+\fBNTP kernel RX timestamps\fP
+.RS 4
+The number of NTP responses which included a receive timestamp captured by the
+kernel.
+.RE
+.sp
+\fBNTP kernel TX timestamps\fP
+.RS 4
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the kernel.
+.RE
+.sp
+\fBNTP hardware RX timestamps\fP
+.RS 4
+The number of NTP responses which included a receive timestamp captured by the
+NIC.
+.RE
+.sp
+\fBNTP hardware TX timestamps\fP
+.RS 4
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the NIC.
+.RE
+.RE
+.sp
+\fBallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The effect of the allow command is identical to the
+\fBallow\fP directive in the configuration file.
+.sp
+The syntax is illustrated in the following examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+allow 1.2.3.4
+allow all 3.4.5.0/24
+allow 2001:db8:789a::/48
+allow 0/0
+allow ::/0
+allow
+allow all
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+The effect of the allow command is identical to the
+\fBdeny\fP directive in the configuration file.
+.sp
+The syntax is illustrated in the following examples:
+.sp
+.if n .RS 4
+.nf
+.fam C
+deny 1.2.3.4
+deny all 3.4.5.0/24
+deny 2001:db8:789a::/48
+deny 0/0
+deny ::/0
+deny
+deny all
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBlocal\fP [\fIoption\fP]..., \fBlocal\fP \fBoff\fP
+.RS 4
+The \fBlocal\fP command allows \fBchronyd\fP to be told that it is to appear as a
+reference source, even if it is not itself properly synchronised to an external
+source. This can be used on isolated networks, to allow a computer to be the
+primary time server for other computers.
+.sp
+The first form enables the local reference mode on the host. The syntax is
+identical to the \fBlocal\fP directive in the
+configuration file.
+.sp
+The second form disables the local reference mode.
+.RE
+.sp
+\fBsmoothing\fP
+.RS 4
+The \fBsmoothing\fP command displays the current state of the NTP server time
+smoothing, which can be enabled with the
+\fBsmoothtime\fP directive. An example of the
+output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+Active         : Yes
+Offset         : +1.000268817 seconds
+Frequency      : \-0.142859 ppm
+Wander         : \-0.010000 ppm per second
+Last update    : 17.8 seconds ago
+Remaining time : 19988.4 seconds
+.fam
+.fi
+.if n .RE
+.sp
+The fields are explained as follows:
+.sp
+\fBActive\fP
+.RS 4
+This shows if the server time smoothing is currently active. Possible values
+are \fIYes\fP and \fINo\fP. If the \fBleaponly\fP option is included in the \fBsmoothtime\fP
+directive, \fI(leap second only)\fP will be shown on the line.
+.RE
+.sp
+\fBOffset\fP
+.RS 4
+This is the current offset applied to the time sent to NTP clients. Positive
+value means the clients are getting time that\(cqs ahead of true time.
+.RE
+.sp
+\fBFrequency\fP
+.RS 4
+The current frequency offset of the served time. Negative value means the
+time observed by clients is running slower than true time.
+.RE
+.sp
+\fBWander\fP
+.RS 4
+The current frequency wander of the served time. Negative value means the
+time observed by clients is slowing down.
+.RE
+.sp
+\fBLast update\fP
+.RS 4
+This field shows how long ago the time smoothing process was updated, e.g.
+\fBchronyd\fP accumulated a new measurement.
+.RE
+.sp
+\fBRemaining time\fP
+.RS 4
+The time it would take for the smoothing process to get to zero offset and
+frequency if there were no more updates.
+.RE
+.RE
+.sp
+\fBsmoothtime\fP \fBactivate\fP, \fBsmoothtime\fP \fBreset\fP
+.RS 4
+The \fBsmoothtime\fP command can be used to activate or reset the server time
+smoothing process if it is configured with the
+\fBsmoothtime\fP directive.
+.RE
+.SS "Monitoring access"
+.sp
+\fBcmdaccheck\fP \fIaddress\fP
+.RS 4
+This command is similar to the \fBaccheck\fP command, except that it is
+used to check whether monitoring access is permitted from a named host.
+.sp
+Examples of use are as follows:
+.sp
+.if n .RS 4
+.nf
+.fam C
+cmdaccheck foo.example.net
+cmdaccheck 1.2.3.4
+cmdaccheck 2001:db8::1
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBcmdallow\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBallow\fP command, except that it is used to
+allow particular hosts or subnets to use \fBchronyc\fP to monitor with \fBchronyd\fP on
+the current host.
+.RE
+.sp
+\fBcmddeny\fP [\fBall\fP] [\fIsubnet\fP]
+.RS 4
+This is similar to the \fBdeny\fP command, except that it is used to allow
+particular hosts or subnets to use \fBchronyc\fP to monitor \fBchronyd\fP on the
+current host.
+.RE
+.SS "Real\-time clock (RTC)"
+.sp
+\fBrtcdata\fP
+.RS 4
+The \fBrtcdata\fP command displays the current RTC parameters.
+.sp
+An example output is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+RTC ref time (GMT) : Sat May 30 07:25:56 2015
+Number of samples  : 10
+Number of runs     : 5
+Sample span period :  549
+RTC is fast by     :    \-1.632736 seconds
+RTC gains time at  :  \-107.623 ppm
+.fam
+.fi
+.if n .RE
+.sp
+The fields have the following meaning:
+.sp
+\fBRTC ref time (GMT)\fP
+.RS 4
+This is the RTC reading the last time its error was measured.
+.RE
+.sp
+\fBNumber of samples\fP
+.RS 4
+This is the number of previous measurements being used to determine the RTC
+gain or loss rate.
+.RE
+.sp
+\fBNumber of runs\fP
+.RS 4
+This is the number of runs of residuals of the same sign following the
+regression fit for (RTC error) versus (RTC time). A value which is small
+indicates that the measurements are not well approximated by a linear model,
+and that the algorithm will tend to delete the older measurements to improve
+the fit.
+.RE
+.sp
+\fBSample span period\fP
+.RS 4
+This is the period that the measurements span (from the oldest to the
+newest). Without a unit the value is in seconds; suffixes \fIm\fP for minutes,
+\fIh\fP for hours, \fId\fP for days or \fIy\fP for years can be used.
+.RE
+.sp
+\fBRTC is fast by\fP
+.RS 4
+This is the estimate of how many seconds fast the RTC when it thought
+the time was at the reference time (above). If this value is large, you
+might (or might not) want to use the \fBtrimrtc\fP command to bring the
+RTC into line with the system clock. (Note, a large error will not affect
+\fBchronyd\fP\*(Aqs operation, unless it becomes so big as to start causing rounding
+errors.)
+.RE
+.sp
+\fBRTC gains time at\fP
+.RS 4
+This is the amount of time gained (positive) or lost (negative) by the real
+time clock for each second that it ticks. It is measured in parts per
+million. So if the value shown was +1, suppose the RTC was exactly right when
+it crosses a particular second boundary. Then it would be 1 microsecond fast
+when it crosses its next second boundary.
+.RE
+.RE
+.sp
+\fBtrimrtc\fP
+.RS 4
+The \fBtrimrtc\fP command is used to correct the system\(cqs real\-time clock (RTC) to
+the main system clock. It has no effect if the error between the two clocks is
+currently estimated at less than a second.
+.sp
+The command takes no arguments. It performs the following steps (if the RTC is
+more than 1 second away from the system clock):
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 1.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 1." 4.2
+.\}
+Remember the currently estimated gain or loss rate of the RTC and flush the
+previous measurements.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 2.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 2." 4.2
+.\}
+Step the real\-time clock to bring it within a second of the system clock.
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 3.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 3." 4.2
+.\}
+Make several measurements to accurately determine the new offset between
+the RTC and the system clock (i.e. the remaining fraction of a second
+error).
+.RE
+.sp
+.RS 4
+.ie n \{\
+\h'-04' 4.\h'+01'\c
+.\}
+.el \{\
+.  sp -1
+.  IP " 4." 4.2
+.\}
+Save the RTC parameters to the RTC file (specified with the
+\fBrtcfile\fP directive in the configuration file).
+.RE
+.RE
+.sp
+
+.RS 4
+.sp
+The last step is done as a precaution against the computer suffering a power
+failure before either the daemon exits or the \fBwritertc\fP command
+is issued.
+.sp
+\fBchronyd\fP will still work perfectly well both whilst operating and across
+machine reboots even if the \fBtrimrtc\fP command is never used (and the RTC is
+allowed to drift away from true time). The \fBtrimrtc\fP command is provided as a
+method by which it can be corrected, in a manner compatible with \fBchronyd\fP
+using it to maintain accurate time across machine reboots.
+.sp
+The \fBtrimrtc\fP command can be executed automatically by \fBchronyd\fP with the
+\fBrtcautotrim\fP directive in the configuration
+file.
+.RE
+.sp
+\fBwritertc\fP
+.RS 4
+The \fBwritertc\fP command writes the currently estimated error and gain or loss rate
+parameters for the RTC to the RTC file (specified with the
+\fBrtcfile\fP directive). This information is also
+written automatically when \fBchronyd\fP is killed (by the SIGHUP, SIGINT, SIGQUIT
+or SIGTERM signals) or when the \fBtrimrtc\fP command is issued.
+.RE
+.SS "Other daemon commands"
+.sp
+\fBcyclelogs\fP
+.RS 4
+The \fBcyclelogs\fP command causes all of \fBchronyd\fP\*(Aqs open log files to be closed
+and re\-opened. This allows them to be renamed so that they can be periodically
+purged. An example of how to do this is shown below.
+.sp
+.if n .RS 4
+.nf
+.fam C
+# mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
+# chronyc cyclelogs
+# rm /var/log/chrony/measurements1.log
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBdump\fP
+.RS 4
+The \fBdump\fP command causes \fBchronyd\fP to write its current history of
+measurements for each of its sources to dump files in the directory specified
+in the configuration file by the \fBdumpdir\fP
+directive and also write server NTS keys and client NTS cookies to the
+directory specified by the \fBntsdumpdir\fP
+directive. Note that \fBchronyd\fP does this automatically when it exits. This
+command is mainly useful for inspection whilst \fBchronyd\fP is running.
+.RE
+.sp
+\fBrekey\fP
+.RS 4
+The \fBrekey\fP command causes \fBchronyd\fP to re\-read the key file specified in the
+configuration file by the \fBkeyfile\fP directive. It
+also re\-reads the server NTS keys if
+\fBntsdumpdir\fP is specified and
+automatic rotation is disabled in the
+configuration file.
+.RE
+.sp
+\fBreset\fP \fBsources\fP
+.RS 4
+The \fBreset sources\fP command causes \fBchronyd\fP to drop all measurements and
+switch to the unsynchronised state. This command can help \fBchronyd\fP with
+recovery when the measurements are known to be no longer valid or accurate,
+e.g. due to moving the computer to a different network, or resuming the
+computer from a low\-power state (which resets the system clock). \fBchronyd\fP will
+drop the measurements automatically when it detects the clock has made an
+unexpected jump, but the detection is not completely reliable.
+.RE
+.sp
+\fBshutdown\fP
+.RS 4
+The \fBshutdown\fP command causes \fBchronyd\fP to exit. This is equivalent to sending
+the process the SIGTERM signal.
+.RE
+.SS "Client commands"
+.sp
+\fBdns\fP \fIoption\fP
+.RS 4
+The \fBdns\fP command configures how hostnames and IP addresses are resolved in
+\fBchronyc\fP. IP addresses can be resolved to hostnames when printing results of
+\fBsources\fP, \fBsourcestats\fP, \fBtracking\fP
+and \fBclients\fP commands. Hostnames are resolved in commands that
+take an address as argument.
+.sp
+There are five options:
+.sp
+\fBdns \-n\fP
+.RS 4
+Disables resolving IP addresses to hostnames. Raw IP addresses will be
+displayed.
+.RE
+.sp
+\fBdns +n\fP
+.RS 4
+Enables resolving IP addresses to hostnames. This is the default unless
+\fBchronyc\fP was started with \fB\-n\fP option.
+.RE
+.sp
+\fBdns \-4\fP
+.RS 4
+Resolves hostnames only to IPv4 addresses.
+.RE
+.sp
+\fBdns \-6\fP
+.RS 4
+Resolves hostnames only to IPv6 addresses.
+.RE
+.sp
+\fBdns \-46\fP
+.RS 4
+Resolves hostnames to both address families. This is the default behaviour
+unless \fBchronyc\fP was started with the \fB\-4\fP or \fB\-6\fP option.
+.RE
+.RE
+.sp
+\fBtimeout\fP \fItimeout\fP
+.RS 4
+The \fBtimeout\fP command sets the initial timeout for \fBchronyc\fP requests in
+milliseconds. If no response is received from \fBchronyd\fP, the timeout is doubled
+and the request is resent. The maximum number of retries is configured with the
+\fBretries\fP command.
+.sp
+By default, the timeout is 1000 milliseconds.
+.RE
+.sp
+\fBretries\fP \fIretries\fP
+.RS 4
+The \fBretries\fP command sets the maximum number of retries for \fBchronyc\fP requests
+before giving up. The response timeout is controlled by the
+\fBtimeout\fP command.
+.sp
+The default is 2.
+.RE
+.sp
+\fBkeygen\fP [\fIid\fP [\fItype\fP [\fIbits\fP]]]
+.RS 4
+The \fBkeygen\fP command generates a key that can be added to the
+key file (specified with the \fBkeyfile\fP directive)
+to allow NTP authentication between server and client, or peers. The key is
+generated from the \fI/dev/urandom\fP device and it is printed to standard output.
+.sp
+The command has three optional arguments. The first argument is the key number
+(by default 1), which will be specified with the \fBkey\fP option of the \fBserver\fP
+or \fBpeer\fP directives in the configuration file. The second argument is the name
+of the hash function or cipher (by default SHA1, or MD5 if SHA1 is not
+available). The third argument is the length of the key in bits if a hash
+function was selected, between 80 and 4096 bits (by default 160 bits).
+.sp
+An example is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keygen 73 SHA1 256
+.fam
+.fi
+.if n .RE
+.sp
+which generates a 256\-bit SHA1 key with number 73. The printed line should
+then be securely transferred and added to the key files on both server and
+client, or peers. A different key should be generated for each client or peer.
+.sp
+An example using the AES128 cipher is:
+.sp
+.if n .RS 4
+.nf
+.fam C
+keygen 151 AES128
+.fam
+.fi
+.if n .RE
+.RE
+.sp
+\fBexit\fP, \fBquit\fP
+.RS 4
+The \fBexit\fP and \fBquit\fP commands exit from \fBchronyc\fP and return the user to the shell.
+.RE
+.sp
+\fBhelp\fP
+.RS 4
+The \fBhelp\fP command displays a summary of the commands and their arguments.
+.RE
+.SH "SEE ALSO"
+.sp
+\fBchrony.conf(5)\fP, \fBchronyd(8)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony\-project.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/chronyd.adoc b/doc/chronyd.adoc
new file mode 100644
index 0000000..e44aac5
--- /dev/null
+++ b/doc/chronyd.adoc
@@ -0,0 +1,224 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2009-2017
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= chronyd(8)
+:doctype: manpage
+:man manual: System Administration
+:man source: chrony @CHRONY_VERSION@
+
+== NAME
+
+chronyd - chrony daemon
+
+== SYNOPSIS
+
+*chronyd* [_OPTION_]... [_DIRECTIVE_]...
+
+== DESCRIPTION
+
+*chronyd* is a daemon for synchronisation of the system clock. It can
+synchronise the clock with NTP servers, reference clocks (e.g. a GPS receiver),
+and manual input using wristwatch and keyboard via *chronyc*. It can also
+operate as an NTPv4 (RFC 5905) server and peer to provide a time service to
+other computers in the network.
+
+If no configuration directives are specified on the command line, *chronyd*
+will read them from a configuration file. The compiled-in default location of
+the file is _@SYSCONFDIR@/chrony.conf_.
+
+Informational messages, warnings, and errors will be logged to syslog.
+
+== OPTIONS
+
+*-4*::
+With this option hostnames will be resolved only to IPv4 addresses and only
+IPv4 sockets will be created.
+
+*-6*::
+With this option hostnames will be resolved only to IPv6 addresses and only
+IPv6 sockets will be created.
+
+*-f* _file_::
+This option can be used to specify an alternate location for the configuration
+file. The compiled-in default value is _@SYSCONFDIR@/chrony.conf_.
+
+*-n*::
+When run in this mode, the program will not detach itself from the terminal.
+
+*-d*::
+When run in this mode, the program will not detach itself from the terminal,
+and all messages will be written to the terminal instead of syslog. If
+*chronyd* was compiled with enabled support for debugging, this option can be
+used twice to enable debug messages.
+
+*-l* _file_::
+This option enables writing of log messages to a file instead of syslog or the
+terminal.
+
+*-L* _level_::
+This option specifies the minimum severity level of messages to be written to
+the log file, syslog, or terminal. The following levels can be specified:
+0 (informational), 1 (warning), 2 (non-fatal error), and 3 (fatal error). The
+default value is 0.
+
+*-p*::
+When run in this mode, *chronyd* will print the configuration and exit. It will
+not detach from the terminal. This option can be used to verify the syntax of
+the configuration and get the whole configuration, even if it is split into
+multiple files and read by the *include* or *confdir* directive.
+
+*-q*::
+When run in this mode, *chronyd* will set the system clock once and exit. It
+will not detach from the terminal.
+
+*-Q*::
+This option is similar to the *-q* option, except it only prints the offset
+without making any corrections of the clock and disables server ports to allow
+*chronyd* to be started without root privileges, assuming the configuration
+does not have any directives which would require them (e.g. *refclock*,
+*hwtimestamp*, *rtcfile*, etc).
+
+*-r*::
+This option will try to reload and then delete files containing sample
+histories for each of the servers and reference clocks being used. The
+files are expected to be in the directory specified by the
+<<chrony.conf.adoc#dumpdir,*dumpdir*>>
+directive in the configuration file. This option is useful if you want to stop
+and restart *chronyd* briefly for any reason, e.g. to install a new version.
+However, it should be used only on systems where the kernel can maintain clock
+compensation whilst not under *chronyd*'s control (i.e. Linux, FreeBSD, NetBSD,
+illumos, and macOS 10.13 or later).
+
+*-R*::
+When this option is used, the <<chrony.conf.adoc#initstepslew,*initstepslew*>>
+directive and the <<chrony.conf.adoc#makestep,*makestep*>> directive used with
+a positive limit will be ignored. This option is useful when restarting
+*chronyd* and can be used in conjunction with the *-r* option.
+
+*-s*::
+This option will set the system clock from the computer's real-time clock (RTC)
+or to the last modification time of the file specified by the
+<<chrony.conf.adoc#driftfile,*driftfile*>> directive. Real-time clocks are
+supported only on Linux.
++
+If used in conjunction with the *-r* flag, *chronyd* will attempt to preserve
+the old samples after setting the system clock from the RTC. This can be used
+to allow *chronyd* to perform long term averaging of the gain or loss rate
+across system reboots, and is useful for systems with intermittent access to
+network that are shut down when not in use. For this to work well, it relies
+on *chronyd* having been able to determine accurate statistics for the
+difference between the RTC and system clock last time the computer was on.
++
+If the last modification time of the drift file is later than both the current
+time and the RTC time, the system time will be set to it to restore the time
+when *chronyd* was previously stopped. This is useful on computers that have no
+RTC or the RTC is broken (e.g. it has no battery).
+
+*-t* _timeout_::
+This option sets a timeout (in seconds) after which *chronyd* will exit. If the
+clock is not synchronised, it will exit with a non-zero status. This is useful
+with the *-q* or *-Q* option to shorten the maximum time waiting for
+measurements, or with the *-r* option to limit the time when *chronyd* is
+running, but still allow it to adjust the frequency of the system clock.
+
+*-u* _user_::
+This option sets the name of the system user to which *chronyd* will switch
+after start in order to drop root privileges. It overrides the
+<<chrony.conf.adoc#user,*user*>> directive. The compiled-in default value is
+_@DEFAULT_USER@_.
++
+On Linux, *chronyd* needs to be compiled with support for the *libcap* library.
+On macOS, FreeBSD, NetBSD, and illumos *chronyd* forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+
+*-U*::
+This option disables a check for root privileges to allow *chronyd* to be
+started under a non-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting *chronyd* under a non-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+
+*-F* _level_::
+This option configures system call filters loaded by *chronyd* processes if it
+was compiled with support for the Linux secure computing (seccomp) facility.
+Three levels are defined: 0, 1, 2. The filters are disabled at level 0. At
+levels 1 and 2, *chronyd* will be killed if it makes a system call which is
+blocked by the filters. The level can be specified as a negative number to
+trigger the SIGSYS signal instead of SIGKILL, which can be useful for
+debugging. The default value is 0.
++
+At level 1, the filters allow only selected system calls that are normally
+expected to be made by *chronyd*. Other system calls are blocked. This level is
+recommended only if it is known to work on the version of the system where
+*chrony* is installed. The filters need to allow also system calls made by
+libraries that *chronyd* is using (e.g. libc), but different versions or
+implementations of the libraries might make different system calls. If the
+filters are missing a system call, *chronyd* could be killed even in normal
+operation.
++
+At level 2, the filters block only a small number of specific system calls
+(e.g. fork and exec). This approach should avoid false positives, but the
+protection of the system against a compromised *chronyd* process is much more
+limited.
++
+The filters cannot be enabled with the *mailonchange* directive.
+
+*-P* _priority_::
+On Linux, FreeBSD, NetBSD, and illumos this option will select the SCHED_FIFO
+real-time scheduler at the specified priority (which must be between 0 and
+100). On macOS, this option must have either a value of 0 to disable the thread
+time constraint policy or 1 for the policy to be enabled. Other systems do not
+support this option. The default value is 0.
+
+*-m*::
+This option will lock *chronyd* into RAM so that it will never be paged out.
+This mode is only supported on Linux, FreeBSD, NetBSD, and illumos.
+
+*-x*::
+This option disables the control of the system clock. *chronyd* will not try to
+make any adjustments of the clock. It will assume the clock is free running and
+still track its offset and frequency relative to the estimated true time. This
+option allows *chronyd* to be started without the capability to adjust or set
+the system clock (e.g. in some containers) to operate as an NTP server.
+
+*-v*, *--version*::
+With this option *chronyd* will print version number to the terminal and exit.
+
+*-h*, *--help*::
+With this option *chronyd* will print a help message to the terminal and exit.
+
+== FILES
+
+_@SYSCONFDIR@/chrony.conf_
+
+== SEE ALSO
+
+<<chronyc.adoc#,*chronyc(1)*>>, <<chrony.conf.adoc#,*chrony.conf(5)*>>
+
+== BUGS
+
+For instructions on how to report bugs, please visit
+https://chrony-project.org/.
+
+== AUTHORS
+
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
diff --git a/doc/chronyd.man.in b/doc/chronyd.man.in
new file mode 100644
index 0000000..747bad1
--- /dev/null
+++ b/doc/chronyd.man.in
@@ -0,0 +1,266 @@
+'\" t
+.\"     Title: chronyd
+.\"    Author: [see the "AUTHOR(S)" section]
+.\" Generator: Asciidoctor 2.0.20
+.\"      Date: 2023-08-09
+.\"    Manual: System Administration
+.\"    Source: chrony @CHRONY_VERSION@
+.\"  Language: English
+.\"
+.TH "CHRONYD" "8" "2023-08-09" "chrony @CHRONY_VERSION@" "System Administration"
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.ss \n[.ss] 0
+.nh
+.ad l
+.de URL
+\fI\\$2\fP <\\$1>\\$3
+..
+.als MTO URL
+.if \n[.g] \{\
+.  mso www.tmac
+.  am URL
+.    ad l
+.  .
+.  am MTO
+.    ad l
+.  .
+.  LINKSTYLE blue R < >
+.\}
+.SH "NAME"
+chronyd \- chrony daemon
+.SH "SYNOPSIS"
+.sp
+\fBchronyd\fP [\fIOPTION\fP]... [\fIDIRECTIVE\fP]...
+.SH "DESCRIPTION"
+.sp
+\fBchronyd\fP is a daemon for synchronisation of the system clock. It can
+synchronise the clock with NTP servers, reference clocks (e.g. a GPS receiver),
+and manual input using wristwatch and keyboard via \fBchronyc\fP. It can also
+operate as an NTPv4 (RFC 5905) server and peer to provide a time service to
+other computers in the network.
+.sp
+If no configuration directives are specified on the command line, \fBchronyd\fP
+will read them from a configuration file. The compiled\-in default location of
+the file is \fI@SYSCONFDIR@/chrony.conf\fP.
+.sp
+Informational messages, warnings, and errors will be logged to syslog.
+.SH "OPTIONS"
+.sp
+\fB\-4\fP
+.RS 4
+With this option hostnames will be resolved only to IPv4 addresses and only
+IPv4 sockets will be created.
+.RE
+.sp
+\fB\-6\fP
+.RS 4
+With this option hostnames will be resolved only to IPv6 addresses and only
+IPv6 sockets will be created.
+.RE
+.sp
+\fB\-f\fP \fIfile\fP
+.RS 4
+This option can be used to specify an alternate location for the configuration
+file. The compiled\-in default value is \fI@SYSCONFDIR@/chrony.conf\fP.
+.RE
+.sp
+\fB\-n\fP
+.RS 4
+When run in this mode, the program will not detach itself from the terminal.
+.RE
+.sp
+\fB\-d\fP
+.RS 4
+When run in this mode, the program will not detach itself from the terminal,
+and all messages will be written to the terminal instead of syslog. If
+\fBchronyd\fP was compiled with enabled support for debugging, this option can be
+used twice to enable debug messages.
+.RE
+.sp
+\fB\-l\fP \fIfile\fP
+.RS 4
+This option enables writing of log messages to a file instead of syslog or the
+terminal.
+.RE
+.sp
+\fB\-L\fP \fIlevel\fP
+.RS 4
+This option specifies the minimum severity level of messages to be written to
+the log file, syslog, or terminal. The following levels can be specified:
+0 (informational), 1 (warning), 2 (non\-fatal error), and 3 (fatal error). The
+default value is 0.
+.RE
+.sp
+\fB\-p\fP
+.RS 4
+When run in this mode, \fBchronyd\fP will print the configuration and exit. It will
+not detach from the terminal. This option can be used to verify the syntax of
+the configuration and get the whole configuration, even if it is split into
+multiple files and read by the \fBinclude\fP or \fBconfdir\fP directive.
+.RE
+.sp
+\fB\-q\fP
+.RS 4
+When run in this mode, \fBchronyd\fP will set the system clock once and exit. It
+will not detach from the terminal.
+.RE
+.sp
+\fB\-Q\fP
+.RS 4
+This option is similar to the \fB\-q\fP option, except it only prints the offset
+without making any corrections of the clock and disables server ports to allow
+\fBchronyd\fP to be started without root privileges, assuming the configuration
+does not have any directives which would require them (e.g. \fBrefclock\fP,
+\fBhwtimestamp\fP, \fBrtcfile\fP, etc).
+.RE
+.sp
+\fB\-r\fP
+.RS 4
+This option will try to reload and then delete files containing sample
+histories for each of the servers and reference clocks being used. The
+files are expected to be in the directory specified by the
+\fBdumpdir\fP
+directive in the configuration file. This option is useful if you want to stop
+and restart \fBchronyd\fP briefly for any reason, e.g. to install a new version.
+However, it should be used only on systems where the kernel can maintain clock
+compensation whilst not under \fBchronyd\fP\*(Aqs control (i.e. Linux, FreeBSD, NetBSD,
+illumos, and macOS 10.13 or later).
+.RE
+.sp
+\fB\-R\fP
+.RS 4
+When this option is used, the \fBinitstepslew\fP
+directive and the \fBmakestep\fP directive used with
+a positive limit will be ignored. This option is useful when restarting
+\fBchronyd\fP and can be used in conjunction with the \fB\-r\fP option.
+.RE
+.sp
+\fB\-s\fP
+.RS 4
+This option will set the system clock from the computer\(cqs real\-time clock (RTC)
+or to the last modification time of the file specified by the
+\fBdriftfile\fP directive. Real\-time clocks are
+supported only on Linux.
+.sp
+If used in conjunction with the \fB\-r\fP flag, \fBchronyd\fP will attempt to preserve
+the old samples after setting the system clock from the RTC. This can be used
+to allow \fBchronyd\fP to perform long term averaging of the gain or loss rate
+across system reboots, and is useful for systems with intermittent access to
+network that are shut down when not in use. For this to work well, it relies
+on \fBchronyd\fP having been able to determine accurate statistics for the
+difference between the RTC and system clock last time the computer was on.
+.sp
+If the last modification time of the drift file is later than both the current
+time and the RTC time, the system time will be set to it to restore the time
+when \fBchronyd\fP was previously stopped. This is useful on computers that have no
+RTC or the RTC is broken (e.g. it has no battery).
+.RE
+.sp
+\fB\-t\fP \fItimeout\fP
+.RS 4
+This option sets a timeout (in seconds) after which \fBchronyd\fP will exit. If the
+clock is not synchronised, it will exit with a non\-zero status. This is useful
+with the \fB\-q\fP or \fB\-Q\fP option to shorten the maximum time waiting for
+measurements, or with the \fB\-r\fP option to limit the time when \fBchronyd\fP is
+running, but still allow it to adjust the frequency of the system clock.
+.RE
+.sp
+\fB\-u\fP \fIuser\fP
+.RS 4
+This option sets the name of the system user to which \fBchronyd\fP will switch
+after start in order to drop root privileges. It overrides the
+\fBuser\fP directive. The compiled\-in default value is
+\fI@DEFAULT_USER@\fP.
+.sp
+On Linux, \fBchronyd\fP needs to be compiled with support for the \fBlibcap\fP library.
+On macOS, FreeBSD, NetBSD, and illumos \fBchronyd\fP forks into two processes.
+The child process retains root privileges, but can only perform a very limited
+range of privileged system calls on behalf of the parent.
+.RE
+.sp
+\fB\-U\fP
+.RS 4
+This option disables a check for root privileges to allow \fBchronyd\fP to be
+started under a non\-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting \fBchronyd\fP under a non\-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+.RE
+.sp
+\fB\-F\fP \fIlevel\fP
+.RS 4
+This option configures system call filters loaded by \fBchronyd\fP processes if it
+was compiled with support for the Linux secure computing (seccomp) facility.
+Three levels are defined: 0, 1, 2. The filters are disabled at level 0. At
+levels 1 and 2, \fBchronyd\fP will be killed if it makes a system call which is
+blocked by the filters. The level can be specified as a negative number to
+trigger the SIGSYS signal instead of SIGKILL, which can be useful for
+debugging. The default value is 0.
+.sp
+At level 1, the filters allow only selected system calls that are normally
+expected to be made by \fBchronyd\fP. Other system calls are blocked. This level is
+recommended only if it is known to work on the version of the system where
+\fBchrony\fP is installed. The filters need to allow also system calls made by
+libraries that \fBchronyd\fP is using (e.g. libc), but different versions or
+implementations of the libraries might make different system calls. If the
+filters are missing a system call, \fBchronyd\fP could be killed even in normal
+operation.
+.sp
+At level 2, the filters block only a small number of specific system calls
+(e.g. fork and exec). This approach should avoid false positives, but the
+protection of the system against a compromised \fBchronyd\fP process is much more
+limited.
+.sp
+The filters cannot be enabled with the \fBmailonchange\fP directive.
+.RE
+.sp
+\fB\-P\fP \fIpriority\fP
+.RS 4
+On Linux, FreeBSD, NetBSD, and illumos this option will select the SCHED_FIFO
+real\-time scheduler at the specified priority (which must be between 0 and
+100). On macOS, this option must have either a value of 0 to disable the thread
+time constraint policy or 1 for the policy to be enabled. Other systems do not
+support this option. The default value is 0.
+.RE
+.sp
+\fB\-m\fP
+.RS 4
+This option will lock \fBchronyd\fP into RAM so that it will never be paged out.
+This mode is only supported on Linux, FreeBSD, NetBSD, and illumos.
+.RE
+.sp
+\fB\-x\fP
+.RS 4
+This option disables the control of the system clock. \fBchronyd\fP will not try to
+make any adjustments of the clock. It will assume the clock is free running and
+still track its offset and frequency relative to the estimated true time. This
+option allows \fBchronyd\fP to be started without the capability to adjust or set
+the system clock (e.g. in some containers) to operate as an NTP server.
+.RE
+.sp
+\fB\-v\fP, \fB\-\-version\fP
+.RS 4
+With this option \fBchronyd\fP will print version number to the terminal and exit.
+.RE
+.sp
+\fB\-h\fP, \fB\-\-help\fP
+.RS 4
+With this option \fBchronyd\fP will print a help message to the terminal and exit.
+.RE
+.SH "FILES"
+.sp
+\fI@SYSCONFDIR@/chrony.conf\fP
+.SH "SEE ALSO"
+.sp
+\fBchronyc(1)\fP, \fBchrony.conf(5)\fP
+.SH "BUGS"
+.sp
+For instructions on how to report bugs, please visit
+.URL "https://chrony\-project.org/" "" "."
+.SH "AUTHORS"
+.sp
+chrony was written by Richard Curnow, Miroslav Lichvar, and others.
\ No newline at end of file
diff --git a/doc/faq.adoc b/doc/faq.adoc
new file mode 100644
index 0000000..57347c3
--- /dev/null
+++ b/doc/faq.adoc
@@ -0,0 +1,1103 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2014-2016, 2020-2023
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= Frequently Asked Questions
+:toc:
+:numbered:
+
+== `chrony` compared to other programs
+
+=== How does `chrony` compare to `ntpd`?
+
+`chrony` and `ntpd` are two different implementations of the Network Time
+Protocol (NTP).
+
+`chrony` is a newer implementation, which was designed to work well in a wider
+range of conditions. It can usually synchronise the system clock faster and
+with better time accuracy. It has many features, but it does not implement some
+of the less useful NTP modes like broadcast client or multicast server/client.
+
+If your computer is connected to the Internet only for few minutes at a time,
+the network connection is often congested, you turn your computer off or
+suspend it frequently, the clock is not very stable (e.g. there are rapid
+changes in the temperature or it is a virtual machine), or you want to use NTP
+on an isolated network with no hardware reference clocks in sight, `chrony`
+will probably work better for you.
+
+For a more detailed comparison of features and performance, see the
+https://chrony-project.org/comparison.html[comparison page] on the `chrony`
+website.
+
+=== Should I prefer `chrony` over `timesyncd` if I do not need to run a server?
+
+Generally, yes.
+
+`systemd-timesyncd` is a very simple NTP client included in the `systemd`
+suite. It lacks almost all features of `chrony` and other advanced client
+implementations listed on the
+https://chrony-project.org/comparison.html[comparison page]. One of its main
+limitations is that it cannot poll multiple servers at the same time and detect
+servers having incorrect time (falsetickers in the NTP terminology). It should
+be used only with trusted reliable servers, ideally in local network.
+
+Using `timesyncd` with `pool.ntp.org` is problematic. The pool is very
+robust as a whole, but the individual servers run by volunteers cannot be
+relied on. Occasionally, servers drift away or make a step to distant past or
+future due to misconfiguration, problematic implementation, and other bugs
+(e.g. in firmware of a GPS receiver). The pool monitoring system detects such
+servers and quickly removes them from the pool DNS, but clients like
+`timesyncd` cannot recover from that. They follow the server as long as it
+claims to be synchronised. They need to be restarted in order to get a new
+address from the pool DNS.
+
+Note that the complexity of NTP and clock synchronisation is on the client
+side. The amount of code in `chrony` specific to NTP server is very small and
+it is disabled by default. If it was removed, it would not significantly reduce
+the amount of memory or storage needed.
+
+== Configuration issues
+
+=== What is the minimum recommended configuration for an NTP client?
+
+First, the client needs to know which NTP servers it should ask for the current
+time. They are specified by the `server` or `pool` directive. The `pool`
+directive is used with names that resolve to multiple addresses of different
+servers. For reliable operation, the client should have at least three servers.
+
+The `iburst` option enables a burst of requests to speed up the initial
+synchronisation.
+
+To stabilise the initial synchronisation on the next start, the estimated drift
+of the system clock is saved to a file specified by the `driftfile` directive.
+
+If the system clock can be far from the true time after boot for any reason,
+`chronyd` should be allowed to correct it quickly by stepping instead of
+slewing, which would take a very long time. The `makestep` directive does
+that.
+
+In order to keep the real-time clock (RTC) close to the true time, so the
+system time is reasonably close to the true time when it is initialised on the
+next boot from the RTC, the `rtcsync` directive enables a mode in which the
+system time is periodically copied to the RTC. It is supported on Linux and
+macOS.
+
+If you wanted to use public NTP servers from the
+https://www.pool.ntp.org/[pool.ntp.org] project, the minimal _chrony.conf_ file
+could be:
+
+----
+pool pool.ntp.org iburst
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+----
+
+=== How do I make an NTP server?
+
+By default, `chronyd` does not operate as an NTP server. You need to add an
+`allow` directive to the _chrony.conf_ file in order for `chronyd` to open the
+server NTP port and respond to client requests.
+
+----
+allow 192.168.1.0/24
+----
+
+An `allow` directive with no specified subnet allows access from all IPv4 and
+IPv6 addresses.
+
+=== Should all computers on a LAN be clients of an external server?
+
+It depends on the requirements. Usually, the best configuration is to make one
+computer the server, with the others as clients of it. Add a `local` directive
+to the server's _chrony.conf_ file. This configuration will be better because
+
+* the load on the external connection is less
+* the load on the external NTP server(s) is less
+* if your external connection goes down, the computers on the LAN
+  will maintain a common time with each other.
+
+=== Must I specify servers by IP address if DNS is not available on `chronyd` start?
+
+No, `chronyd` will keep trying to resolve
+the names specified by the `server`, `pool`, and `peer` directives in an
+increasing interval until it succeeds. The `online` command can be issued from
+`chronyc` to force `chronyd` to try to resolve the names immediately.
+
+=== How can I make `chronyd` more secure?
+
+If you do not need to use `chronyc`, or you want to run `chronyc` only
+under the root or _chrony_ user (which can access `chronyd` through a Unix
+domain socket), you can disable the IPv4 and IPv6 command sockets (by default
+listening on localhost) by adding `cmdport 0` to the configuration file.
+
+You can specify an unprivileged user with the `-u` option, or the `user`
+directive in the _chrony.conf_ file, to which `chronyd` will switch after start
+in order to drop root privileges. The configure script has a `--with-user`
+option, which sets the default user. On Linux, `chronyd` needs to be compiled
+with support for the `libcap` library. On other systems, `chronyd` forks into
+two processes. The child process retains root privileges, but can only perform
+a very limited range of privileged system calls on behalf of the parent.
+
+Also, if `chronyd` is compiled with support for the Linux secure computing
+(seccomp) facility, you can enable a system call filter with the `-F` option.
+It will significantly reduce the kernel attack surface and possibly prevent
+kernel exploits from the `chronyd` process if it is compromised. It is
+recommended to enable the filter only when it is known to work on the version of
+the system where `chrony` is installed as the filter needs to allow also system
+calls made from libraries that `chronyd` is using (e.g. libc) and different
+versions or implementations of the libraries might make different system calls.
+If the filter is missing some system call, `chronyd` could be killed even in
+normal operation.
+
+=== How can I make the system clock more secure?
+
+An NTP client synchronising the system clock to an NTP server is susceptible to
+various attacks, which can break applications and network protocols relying on
+accuracy of the clock (e.g. DNSSEC, Kerberos, TLS, WireGuard).
+
+Generally, a man-in-the-middle (MITM) attacker between the client and server
+can
+
+* make fake responses, or modify real responses from the server, to create an
+  arbitrarily large time and frequency offset, make the server appear more
+  accurate, insert a leap second, etc.
+* delay the requests and/or responses to create a limited time offset and
+  temporarily also a limited frequency offset
+* drop the requests or responses to prevent updates of the clock with new
+  measurements
+* redirect the requests to a different server
+
+The attacks can be combined for a greater effect. The attacker can delay
+packets to create a significant frequency offset first and then drop all
+subsequent packets to let the clock quickly drift away from the true time.
+The attacker might also be able to control the server's clock.
+
+Some attacks cannot be prevented. Monitoring is needed for detection, e.g. the
+reachability register in the `sources` report shows missing packets. The extent
+to which the attacker can control the client's clock depends on its
+configuration.
+
+Enable authentication to prevent `chronyd` from accepting modified, fake, or
+redirected packets. It can be enabled with a symmetric key specified by the
+`key` option, or Network Time Security (NTS) by the `nts` option (supported
+since `chrony` version 4.0). The server needs to support the selected
+authentication mechanism. Symmetric keys have to be configured on both client
+and server, and each client must have its own key (one per server).
+
+The maximum offset that the attacker can insert in an NTP measurement by
+delaying packets can be limited by the `maxdelay` option. The default value is
+3 seconds. The measured delay is reported as the peer delay in the `ntpdata`
+report and `measurements` log. Set the `maxdelay` option to a value larger than
+the maximum value that is normally observed. Note that the delay can increase
+significantly even when not under an attack, e.g. when the network is congested
+or the routing has changed.
+
+The maximum accepted change in time offset between clock updates can be limited
+by the `maxchange` directive. Larger changes in the offset will be ignored or
+cause `chronyd` to exit. Note that the attacker can get around this limit by
+splitting the offset into multiple smaller offsets and/or creating a large
+frequency offset. When this directive is used, `chronyd` will have to be
+restarted after a successful attack. It will not be able to recover on its own.
+It must not be restarted automatically (e.g. by the service manager).
+
+The impact of a large accepted time offset can be reduced by disabling clock
+steps, i.e. by not using the `makestep` and `initstepslew` directives. The
+offset will be slowly corrected by speeding up or slowing down the clock at a
+rate which can be limited by the `maxslewrate` directive. Disabling clock steps
+completely is practical only if the clock cannot gain a larger error on its
+own, e.g. when the computer is shut down or suspended, and the `maxslewrate`
+limit is large enough to correct an expected error in an acceptable time. The
+`rtcfile` directive with the `-s` option can be used to compensate for the RTC
+drift.
+
+A more practical approach is to enable `makestep` for a limited number of clock
+updates (the 2nd argument of the directive) and limit the offset change in all
+updates by the `maxchange` directive. The attacker will be able to make only a
+limited step and only if the attack starts in a short window after booting the
+computer, or when `chronyd` is restarted without the `-R` option.
+
+The frequency offset can be limited by the `maxdrift` directive. The measured
+frequency offset is reported in the drift file, `tracking` report, and
+`tracking` log. Set `maxdrift` to a value larger than the maximum absolute
+value that is normally observed. Note that the frequency of the clock can
+change due to aging of the crystal, differences in calibration of the clock
+source between reboots, migrated virtual machine, etc. A typical computer clock
+has a drift smaller than 100 parts per million (ppm), but much larger drifts
+are possible (e.g. in some virtual machines).
+
+Use only trusted servers, which you expect to be well configured and managed,
+using authentication for their own servers, etc. Use multiple servers, ideally
+in different locations. The attacker will have to deal with a majority of the
+servers in order to pass the source selection and update the clock with a large
+offset. Use the `minsources` directive to increase the required number of
+selectable sources to make the selection more robust.
+
+Do not specify servers as peers. The symmetric mode is less secure than the
+client/server mode. If not authenticated, it is vulnerable to off-path
+denial-of-service attacks, and even when it is authenticated, it is still
+susceptible to replay attacks.
+
+Mixing of authenticated and unauthenticated servers should generally be
+avoided. If mixing is necessary (e.g. for a more accurate and stable
+synchronisation to a closer server which does not support authentication), the
+authenticated servers should be configured as trusted and required to not allow
+the unauthenticated servers to override the authenticated servers in the source
+selection. Since `chrony` version 4.0, the selection options are enabled in
+such a case automatically. This behaviour can be disabled or modified by the
+`authselectmode` directive.
+
+An example of a client configuration limiting the impact of the attacks could
+be
+
+----
+server foo.example.net iburst nts maxdelay 0.1
+server bar.example.net iburst nts maxdelay 0.2
+server baz.example.net iburst nts maxdelay 0.05
+server qux.example.net iburst nts maxdelay 0.1
+server quux.example.net iburst nts maxdelay 0.1
+minsources 3
+maxchange 100 0 0
+makestep 0.001 1
+maxdrift 100
+maxslewrate 100
+driftfile /var/lib/chrony/drift
+ntsdumpdir /var/lib/chrony
+rtcsync
+----
+
+=== How can I improve the accuracy of the system clock with NTP sources?
+
+Select NTP servers that are well synchronised, stable and close to your
+network. It is better to use more than one server. Three or four is usually
+recommended as the minimum, so `chronyd` can detect servers that serve false
+time and combine measurements from multiple sources.
+
+If you have a network card with hardware timestamping supported on Linux, it
+can be enabled by the `hwtimestamp` directive. It should make local receive and
+transmit timestamps of NTP packets much more stable and accurate.
+
+The `server` directive has some useful options: `minpoll`, `maxpoll`,
+`polltarget`, `maxdelay`, `maxdelayratio`, `maxdelaydevratio`, `xleave`,
+`filter`.
+
+The first three options set the minimum and maximum allowed polling interval,
+and how should be the actual interval adjusted in the specified range. Their
+default values are 6 (64 seconds) for `minpoll`, 10 (1024 seconds) for
+`maxpoll` and 8 (samples) for `polltarget`. The default values should be used
+for general servers on the Internet. With your own NTP servers, or if you have
+permission to poll some servers more frequently, setting these options for
+shorter polling intervals might significantly improve the accuracy of the
+system clock.
+
+The optimal polling interval depends mainly on two factors, stability of the
+network latency and stability of the system clock (which mainly depends on the
+temperature sensitivity of the crystal oscillator and the maximum rate of the
+temperature change).
+
+Generally, if the `sourcestats` command usually reports a small number of
+samples retained for a source (e.g. fewer than 16), a shorter polling interval
+should be considered. If the number of samples is usually at the maximum of 64,
+a longer polling interval might work better.
+
+An example of the directive for an NTP server on the Internet that you are
+allowed to poll frequently could be
+
+----
+server foo.example.net minpoll 4 maxpoll 6 polltarget 16
+----
+
+An example using shorter polling intervals with a server located in the same
+LAN could be
+
+----
+server ntp.local minpoll 2 maxpoll 4 polltarget 30
+----
+
+The maxdelay options are useful to ignore measurements with an unusually large
+delay (e.g. due to congestion in the network) and improve the stability of the
+synchronisation. The `maxdelaydevratio` option could be added to the example
+with local NTP server
+
+----
+server ntp.local minpoll 2 maxpoll 4 polltarget 30 maxdelaydevratio 2
+----
+
+If your server supports the interleaved mode (e.g. it is running `chronyd`),
+the `xleave` option should be added to the `server` directive to enable the
+server to provide the client with more accurate transmit timestamps (kernel or
+preferably hardware). For example:
+
+----
+server ntp.local minpoll 2 maxpoll 4 xleave
+----
+
+When combined with local hardware timestamping, good network switches, and even
+shorter polling intervals, a sub-microsecond accuracy and stability of a few
+tens of nanoseconds might be possible. For example:
+
+----
+server ntp.local minpoll 0 maxpoll 0 xleave
+hwtimestamp eth0
+----
+
+For best stability, the CPU should be running at a constant frequency (i.e.
+disabled power saving and performance boosting). Energy-Efficient Ethernet
+(EEE) should be disabled in the network. The switches should be configured to
+prioritize NTP packets, especially if the network is expected to be heavily
+loaded. The `dscp` directive can be used to set the Differentiated Services
+Code Point in transmitted NTP packets if needed.
+
+If it is acceptable for NTP clients in the network to send requests at a high
+rate, a sub-second polling interval can be specified. A median filter
+can be enabled in order to update the clock at a reduced rate with more stable
+measurements. For example:
+
+----
+server ntp.local minpoll -6 maxpoll -6 filter 15 xleave
+hwtimestamp eth0 minpoll -6
+----
+
+Since `chrony` version 4.3, the minimum `minpoll` is -7 and a filter using a
+long-term estimate of a delay quantile can be enabled by the `maxdelayquant`
+option to replace the default `maxdelaydevratio` filter, which is sensitive to
+outliers corrupting the minimum delay. For example:
+
+----
+server ntp.local minpoll -7 maxpoll -7 filter 31 maxdelayquant 0.3 xleave
+----
+
+As an experimental feature added in version 4.2, `chronyd` supports an NTPv4
+extension field containing an additional timestamp to enable frequency transfer
+and significantly improve stability of synchronisation. It can be enabled by
+the `extfield F323` option. For example:
+
+----
+server ntp.local minpoll 0 maxpoll 0 xleave extfield F323
+----
+
+=== Does `chronyd` have an ntpdate mode?
+
+Yes. With the `-q` option `chronyd` will set the system clock once and exit.
+With the `-Q` option it will print the measured offset without setting the
+clock. If you do not want to use a configuration file, NTP servers can be
+specified on the command line. For example:
+
+----
+# chronyd -q 'pool pool.ntp.org iburst'
+----
+
+The command above would normally take about 5 seconds if the servers were
+well synchronised and responding to all requests. If not synchronised or
+responding, it would take about 10 seconds for `chronyd` to give up and exit
+with a non-zero status. A faster configuration is possible. A single server can
+be used instead of four servers, the number of measurements can be reduced with
+the `maxsamples` option to one (supported since `chrony` version 4.0), and a
+timeout can be specified with the `-t` option. The following command would take
+only up to about one second.
+
+----
+# chronyd -q -t 1 'server pool.ntp.org iburst maxsamples 1'
+----
+
+It is not recommended to run `chronyd` with the `-q` option periodically (e.g.
+from a cron job) as a replacement for the daemon mode, because it performs
+significantly worse (e.g. the clock is stepped and its frequency is not
+corrected). If you must run it this way and you are using a public NTP server,
+make sure `chronyd` does not always start around the first second of a minute,
+e.g. by adding a random sleep before the `chronyd` command. Public servers
+typically receive large bursts of requests around the first second as there is
+a large number of NTP clients started from cron with no delay.
+
+=== Can `chronyd` be configured to control the clock like `ntpd`?
+
+It is not possible to perfectly emulate `ntpd`, but there are some options that
+can configure `chronyd` to behave more like `ntpd` if there is a reason to
+prefer that.
+
+In the following example the `minsamples` directive slows down the response to
+changes in the frequency and offset of the clock. The `maxslewrate` and
+`corrtimeratio` directives reduce the maximum frequency error due to an offset
+correction and the `maxdrift` directive reduces the maximum assumed frequency
+error of the clock. The `makestep` directive enables a step threshold and the
+`maxchange` directive enables a panic threshold. The `maxclockerror` directive
+increases the minimum dispersion rate.
+
+----
+minsamples 32
+maxslewrate 500
+corrtimeratio 100
+maxdrift 500
+makestep 0.128 -1
+maxchange 1000 1 1
+maxclockerror 15
+----
+
+Note that increasing `minsamples` might cause the offsets in the `tracking` and
+`sourcestats` reports/logs to be significantly smaller than the actual offsets
+and be unsuitable for monitoring.
+
+=== Can NTP server be separated from NTP client?
+
+Yes, it is possible to run multiple instances of `chronyd` on a computer at the
+same time. One can operate primarily as an NTP client to synchronise the system
+clock and another as a server for other computers. If they use the same
+filesystem, they need to be configured with different pidfiles, Unix domain
+command sockets, and any other file or directory specified in the configuration
+file. If they run in the same network namespace, they need to use different NTP
+and command ports, or bind the ports to different addresses or interfaces.
+
+The server instance should be started with the `-x` option to prevent it from
+adjusting the system clock and interfering with the client instance. It can be
+configured as a client to synchronise its NTP clock to other servers, or the
+client instance running on the same computer. In the latter case, the `copy`
+option (added in `chrony` version 4.1) can be used to assume the reference ID
+and stratum of the client instance, which enables detection of synchronisation
+loops with its own clients.
+
+On Linux, starting with `chrony` version 4.0, it is possible to run multiple
+server instances sharing a port to better utilise multiple cores of the CPU.
+Note that for rate limiting and client/server interleaved mode to work well
+it is necessary that all packets received from the same address are handled by
+the same server instance.
+
+An example configuration of the client instance could be
+
+----
+pool pool.ntp.org iburst
+allow 127.0.0.1
+port 11123
+driftfile /var/lib/chrony/drift
+makestep 1 3
+rtcsync
+----
+
+and configuration of the first server instance could be
+
+----
+server 127.0.0.1 port 11123 minpoll 0 maxpoll 0 copy
+allow
+cmdport 11323
+bindcmdaddress /var/run/chrony/chronyd-server1.sock
+pidfile /var/run/chronyd-server1.pid
+driftfile /var/lib/chrony/drift-server1
+----
+
+=== Should be a leap smear enabled on NTP server?
+
+With the `smoothtime` and `leapsecmode` directives it is possible to enable a
+server leap smear in order to hide leap seconds from clients and force them to
+follow a slow server's adjustment instead.
+
+This feature should be used only in local networks and only when necessary,
+e.g. when the clients cannot be configured to handle the leap seconds as
+needed, or their number is so large that configuring them all would be
+impractical. The clients should use only one leap-smearing server, or multiple
+identically configured leap-smearing servers. Note that some clients can get
+leap seconds from other sources (e.g. with the `leapsectz` directive in
+`chrony`) and they will not work correctly with a leap smearing server.
+
+=== How should `chronyd` be configured with `gpsd`?
+
+A GPS or other GNSS receiver can be used as a reference clock with `gpsd`. It
+can work as one or two separate time sources for each connected receiver. The
+first time source is based on timestamping of messages sent by the receiver.
+Typically, it is accurate to milliseconds. The other source is much more
+accurate. It is timestamping a pulse-per-second (PPS) signal, usually connected
+to a serial port (e.g. DCD pin) or GPIO pin.
+
+If the PPS signal is connected to the serial port which is receiving messages
+from the GPS/GNSS receiver, `gpsd` should detect and use it automatically. If
+it is connected to a GPIO pin, or another serial port, the PPS device needs to
+be specified on the command line as an additional data source. On Linux, the
+`ldattach` utility can be used to create a PPS device for a serial device.
+
+The PPS-based time source provided by `gpsd` is available as a `SHM 1`
+refclock, or other odd number if `gpsd` is configured with multiple receivers,
+and also as `SOCK /var/run/chrony.DEV.sock` where `DEV` is the name of the
+serial device (e.g. ttyS0).
+
+The message-based time source is available as a `SHM 0` refclock (or other even
+number) and since `gpsd` version 3.25 also as
+`SOCK /var/run/chrony.clk.DEV.sock` where `DEV` is the name of the serial
+device.
+
+The SOCK refclocks should be preferred over SHM for better security
+(the shared memory segment needs to be created by `chronyd` or `gpsd` with an
+expected owner and permissions before an untrusted application or user has a
+chance to create its own in order to feed `chronyd` with false measurements).
+`gpsd` needs to be started after `chronyd` in order to connect to the socket.
+
+With `chronyd` and `gpsd` both supporting PPS, there are two different
+recommended configurations:
+
+----
+# First option
+refclock SOCK /var/run/chrony.ttyS0.sock refid GPS
+
+# Second option
+refclock PPS /dev/pps0 lock NMEA refid GPS
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.1 refid NMEA noselect
+----
+
+They both have some advantages:
+
+* `SOCK` can be more accurate than `PPS` if `gpsd` corrects for the
+  sawtooth error provided by the receiver in serial data
+* `PPS` can be used with higher PPS rates (specified by the `rate` option),
+  but it requires a second refclock or another time source to pair pulses
+  with seconds, and the `SOCK` offset needs to be specified
+  <<using-pps-refclock,correctly>> to compensate for the message delay, while
+  `gpsd` can apply HW-specific information
+
+If the PPS signal is not available, or cannot be used for some reason, the only
+option is the message-based timing
+
+----
+refclock SOCK /var/run/chrony.clk.ttyS0.sock offset 0.5 delay 0.1 refid GPS
+----
+
+or the SHM equivalent if using `gpsd` version before 3.25
+
+----
+refclock SHM 0 offset 0.5 delay 0.1 refid GPS
+----
+
+=== Does `chrony` support PTP?
+
+No, the Precision Time Protocol (PTP) is not supported as a protocol for
+synchronisation of clocks and there are no plans
+to support it. It is a complex protocol, which shares some issues with the
+NTP broadcast mode. One of the main differences between NTP and PTP is that PTP
+was designed to be easily supported in hardware (e.g. network switches and
+routers) in order to make more stable and accurate measurements. PTP relies on
+the hardware support. NTP does not rely on any support in the hardware, but if
+it had the same support as PTP, it could perform equally well.
+
+On Linux, `chrony` supports hardware clocks that some NICs have for PTP. They
+are called PTP hardware clocks (PHC). They can be used as reference clocks
+(specified by the `refclock` directive) and for hardware timestamping of NTP
+packets (enabled by the `hwtimestamp` directive) if the NIC can timestamp other
+packets than PTP, which is usually the case at least for transmitted packets.
+The `ethtool -T` command can be used to verify the timestamping support.
+
+As an experimental feature added in version 4.2, `chrony` can use PTP as a
+transport for NTP messages (NTP over PTP) to enable hardware timestamping on
+hardware which can timestamp PTP packets only. It can be enabled by the
+`ptpport` directive.
+
+=== How can I avoid using wrong PHC refclock?
+
+If your system has multiple PHC devices, normally named by `udev` as
+_/dev/ptp0_, _/dev/ptp1_, and so on, their order can change randomly across
+reboots depending on the order of initialisation of their drivers. If a PHC
+refclock is specified by this name, `chronyd` could be using a wrong refclock
+after reboot. To prevent that, you can configure `udev` to create a stable
+symlink for `chronyd` with a rule like this (e.g. written to
+_/etc/udev/rules.d/80-phc.rules_):
+
+----
+KERNEL=="ptp[0-9]*", DEVPATH=="/devices/pci0000:00/0000:00:01.2/0000:02:00.0/ptp/*", SYMLINK+="ptp-i350-1"
+----
+
+You can get the full _DEVPATH_ of an existing PHC device with the `udevadm
+info` command. You will need to execute the `udevadm trigger` command, or
+reboot the system, for these changes to take effect.
+
+=== Why are client log records dropped before reaching `clientloglimit`?
+
+The number of dropped client log records reported by the `serverstats` command
+can be increasing before the number of clients reported by the `clients` command
+reaches the maximum value corresponding to the memory limit set by the
+`clientloglimit` directive.
+
+This is due to the design of the data structure keeping the client records. It
+is a hash table which can store only up to 16 colliding addresses per slot. If
+a slot has more collisions and the table already has the maximum size, the
+oldest record will be dropped and replaced by the new client.
+
+Note that the size of the table is always a power of two and it can only grow.
+The limit set by the `clientloglimit` directive takes into account that two
+copies of the table exist when it is being resized. This means the actual
+memory usage reported by `top` and other utilities can be significantly smaller
+than the limit even when the maximum number of records is used.
+
+The absolute maximum number of client records kept at the same time is
+16777216.
+
+=== What happened to the `commandkey` and `generatecommandkey` directives?
+
+They were removed in version 2.2. Authentication is no longer supported in the
+command protocol. Commands that required authentication are now allowed only
+through a Unix domain socket, which is accessible only by the root and _chrony_
+users. If you need to configure `chronyd` remotely or locally without the root
+password, please consider using ssh and/or sudo to run `chronyc` under the root
+or _chrony_ user on the host where `chronyd` is running.
+
+== Computer is not synchronising
+
+This is the most common problem. There are a number of reasons, see the
+following questions.
+
+=== Behind a firewall?
+
+Check the `Reach` value printed by the ``chronyc``'s `sources` command. If it
+is zero, it means `chronyd` did not get any valid responses from the NTP server
+you are trying to use. If there is a firewall between you and the server, the
+requests sent to the UDP port 123 of the server or responses sent back from
+the port might be blocked. Try using a tool like `wireshark` or `tcpdump` to
+see if you are getting any responses from the server.
+
+When `chronyd` is receiving responses from the servers, the output of the
+`sources` command issued few minutes after `chronyd` start might look like
+this:
+
+----
+MS Name/IP address         Stratum Poll Reach LastRx Last sample
+===============================================================================
+^* foo.example.net               2   6   377    34   +484us[ -157us] +/-   30ms
+^- bar.example.net               2   6   377    34    +33ms[  +32ms] +/-   47ms
+^+ baz.example.net               3   6   377    35  -1397us[-2033us] +/-   60ms
+----
+
+=== Are NTP servers specified with the `offline` option?
+
+Check that the ``chronyc``'s `online` and `offline` commands are used
+appropriately (e.g. in the system networking scripts). The `activity` command
+prints the number of sources that are currently online and offline. For
+example:
+
+----
+200 OK
+3 sources online
+0 sources offline
+0 sources doing burst (return to online)
+0 sources doing burst (return to offline)
+0 sources with unknown address
+----
+
+=== Is name resolution working correctly?
+
+NTP servers specified by their hostname (instead of an IP address) have to have
+their names resolved before `chronyd` can send any requests to them. If the
+`activity` command prints a non-zero number of sources with unknown address,
+there is an issue with the resolution. Typically, a DNS server is specified in
+_/etc/resolv.conf_. Make sure it is working correctly.
+
+Since `chrony` version 4.0, you can run `chronyc -N sources -a` command to
+print all sources, even those that do not have a known address yet, with their
+names as they were specified in the configuration. This can be useful to verify
+that the names specified in the configuration are used as expected.
+
+=== Is `chronyd` allowed to step the system clock?
+
+By default, `chronyd` adjusts the clock gradually by slowing it down or
+speeding it up. If the clock is too far from the true time, it will take
+a long time to correct the error. The `System time` value printed by the
+``chronyc``'s `tracking` command is the remaining correction that needs to be
+applied to the system clock.
+
+The `makestep` directive can be used to allow `chronyd` to step the clock. For
+example, if _chrony.conf_ had
+
+----
+makestep 1 3
+----
+
+the clock would be stepped in the first three updates if its offset was larger
+than one second. Normally, it is recommended to allow the step only in the first
+few updates, but in some cases (e.g. a computer without an RTC or virtual
+machine which can be suspended and resumed with an incorrect time) it might be
+necessary to allow the step on any clock update. The example above would change
+to
+
+----
+makestep 1 -1
+----
+
+=== Using NTS?
+
+The Network Time Security (NTS) mechanism uses Transport Layer Security (TLS)
+to establish the keys needed for authentication of NTP packets.
+
+Run the `authdata` command to check whether the key establishment was
+successful:
+
+----
+# chronyc -N authdata
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256  33m    0    0    8  100
+bar.example.net              NTS     1   15  256  33m    0    0    8  100
+baz.example.net              NTS     1   15  256  33m    0    0    8  100
+----
+
+The KeyID, Type, and KLen columns should have non-zero values. If they are
+zero, check the system log for error messages from `chronyd`. One possible
+cause of failure is a firewall blocking the client's connection to the server's
+TCP port 4460.
+
+Another possible cause of failure is a certificate that is failing to verify
+because the client's clock is wrong. This is a chicken-and-egg problem with NTS.
+You might need to manually correct the date, or temporarily disable NTS, in
+order to get NTS working. If your computer has an RTC and it is backed up by a
+good battery, this operation should be needed only once, assuming the RTC will
+be set periodically with the `rtcsync` directive, or compensated with the
+`rtcfile` directive and the `-s` option.
+
+If the computer does not have an RTC or battery, you can use the `-s` option
+without `rtcfile` directive to restore time of the last shutdown or reboot from
+the drift file. The clock will start behind the true time, but if the computer
+was not shut down for too long and the server's certificate was not renewed too
+close to its expiration, it should be sufficient for the time checks to
+succeed.
+
+If you run your own server, you can use a self-signed certificate covering
+all dates where the client can start (e.g. years 1970-2100). The certificate
+needs to be installed on the client and specified with the `ntstrustedcerts`
+directive. The server can have multiple names and certificates. To avoid
+trusting a certificate for too long, a new certificate can be added to the
+server periodically (e.g. once per year) and the client can have the server
+name and trusted certificate updated automatically (e.g. using a package
+repository, or a cron script downloading the files directly from the server
+over HTTPS). A client that was shut down for years will still be able to
+synchronise its clock and perform the update as long as the server keeps
+the old certificate.
+
+As a last resort, you can disable the time checks by the `nocerttimecheck`
+directive. This has some important security implications. To reduce the
+security risk, you can use the `nosystemcert` and `ntstrustedcerts` directives
+to disable the system's default trusted certificate authorities and trust only
+a minimal set of selected authorities needed to validate the certificates of
+used NTP servers.
+
+=== Using a Windows NTP server?
+
+A common issue with Windows NTP servers is that they report a very large root
+dispersion (e.g. three seconds or more), which causes `chronyd` to ignore the
+server for being too inaccurate. The `sources` command might show a valid
+measurement, but the server is not selected for synchronisation. You can check
+the root dispersion of the server with the ``chronyc``'s `ntpdata` command.
+
+The `maxdistance` value needs to be increased in _chrony.conf_ to enable
+synchronisation to such a server. For example:
+
+----
+maxdistance 16.0
+----
+
+=== An unreachable source is selected?
+
+When `chronyd` is configured with multiple time sources, it tries to select the
+most accurate and stable sources for synchronisation of the system clock. They
+are marked with the _*_ or _+_ symbol in the report printed by the `sources`
+command.
+
+When the best source (marked with the _*_ symbol) becomes unreachable (e.g. NTP
+server stops responding), `chronyd` will not immediately switch
+to the second best source in an attempt to minimise the error of the clock. It
+will let the clock run free for as long as its estimated error (in terms of
+root distance) based on previous measurements is smaller than the estimated
+error of the second source, and there is still an interval which contains some
+measurements from both sources.
+
+If the first source was significantly better than the second source, it can
+take many hours before the second source is selected, depending on its polling
+interval. You can force a faster reselection by increasing the clock error rate
+(`maxclockerror` directive), shortening the polling interval (`maxpoll`
+option), or reducing the number of samples (`maxsamples` option).
+
+=== Does selected source drop new measurements?
+
+`chronyd` can drop a large number of successive NTP measurements if they are
+not passing some of the NTP tests. The `sources` command can report for a
+selected source the fully-reachable value of 377 in the Reach column and at the
+same time a LastRx value that is much larger than the current polling interval.
+If the source is online, this indicates that a number of measurements was
+dropped. You can use the `ntpdata` command to check the NTP tests for the last
+measurement. Usually, it is the test C which fails.
+
+This can be an issue when there is a long-lasting increase in the measured
+delay, e.g. due to a routing change in the network. Unfortunately, `chronyd`
+does not know for how long it should wait for the delay to come back to the
+original values, or whether it is a permanent increase and it should start from
+scratch.
+
+The test C is an adaptive filter. It can take many hours before it accepts
+a measurement with the larger delay, and even much longer before it drops all
+measurements with smaller delay, which determine an expected delay used by the
+test. You can use the `reset sources` command to drop all measurements
+immediately (available in chrony 4.0 and later). If this issue happens
+frequently, you can effectively disable the test by setting the
+`maxdelaydevratio` option to a very large value (e.g. 1000000), or speed up the
+recovery by increasing the clock error rate with the `maxclockerror` directive.
+
+[[using-pps-refclock]]
+=== Using a PPS reference clock?
+
+A pulse-per-second (PPS) reference clock requires a non-PPS time source to
+determine which second of UTC corresponds to each pulse. If it is another
+reference clock specified with the `lock` option in the `refclock` directive,
+the offset between the two reference clocks must be smaller than 0.4 seconds
+(0.2 seconds with `chrony` versions before 4.1) in
+order for the PPS reference clock to work. With NMEA reference clocks it is
+common to have a larger offset. It needs to be corrected with the `offset`
+option.
+
+One approach to find out a good value of the `offset` option is to configure
+the reference clocks with the `noselect` option and compare them to an NTP
+server. For example, if the `sourcestats` command showed
+
+----
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+PPS0                        0   0     0     +0.000   2000.000     +0ns  4000ms
+NMEA                       58  30   231    -96.494     38.406   +504ms  6080us
+foo.example.net             7   3   200     -2.991     16.141   -107us   492us
+----
+
+the offset of the NMEA source would need to be increased by about 0.504
+seconds. It does not have to be very accurate. As long as the offset of the
+NMEA reference clock stays below the limit, the PPS reference clock should be
+able to determine the seconds corresponding to the pulses and allow the samples
+to be used for synchronisation.
+
+== Issues with `chronyc`
+
+=== I keep getting the error `506 Cannot talk to daemon`
+
+When accessing `chronyd` remotely, make sure that the _chrony.conf_ file (on
+the computer where `chronyd` is running) has a `cmdallow` entry for the
+computer you are running `chronyc` on and an appropriate `bindcmdaddress`
+directive. This is not necessary for localhost.
+
+Perhaps `chronyd` is not running. Try using the `ps` command (e.g. on Linux,
+`ps -auxw`) to see if it is running. Or try `netstat -a` and see if the UDP
+port 323 is listening. If `chronyd` is not running, you might have a problem
+with the way you are trying to start it (e.g. at boot time).
+
+Perhaps you have a firewall set up in a way that blocks packets on the UDP
+port 323. You need to amend the firewall configuration in this case.
+
+=== I keep getting the error `501 Not authorised`
+
+This error indicates that `chronyc` sent the command to `chronyd` using a UDP
+socket instead of the Unix domain socket (e.g. _/var/run/chrony/chronyd.sock_),
+which is required for some commands. For security reasons, only the root and
+_chrony_ users are allowed to access the socket.
+
+It is also possible that the socket does not exist. `chronyd` will not create
+the socket if the directory has a wrong owner or permissions. In this case
+there should be an error message from `chronyd` in the system log.
+
+=== What is the reference ID reported by the `tracking` command?
+
+The reference ID is a 32-bit value used in NTP to prevent synchronisation
+loops.
+
+In `chrony` versions before 3.0 it was printed in the
+quad-dotted notation, even if the reference source did not actually have an
+IPv4 address. For IPv4 addresses, the reference ID is equal to the address, but
+for IPv6 addresses it is the first 32 bits of the MD5 sum of the address. For
+reference clocks, the reference ID is the value specified with the `refid`
+option in the `refclock` directive.
+
+Since version 3.0, the reference ID is printed as a hexadecimal number to avoid
+confusion with IPv4 addresses.
+
+If you need to get the IP address of the current reference source, use the `-n`
+option to disable resolving of IP addresses and read the second field (printed
+in parentheses) on the `Reference ID` line.
+
+=== Is the `chronyc` / `chronyd` protocol documented anywhere?
+
+Only by the source code. See _cmdmon.c_ (`chronyd` side) and _client.c_
+(`chronyc` side).
+
+Note that this protocol is not compatible with the mode 6 or mode 7 protocol
+supported by `ntpd`, i.e. the `ntpq` or `ntpdc` utility cannot be used to
+monitor `chronyd`, and `chronyc` cannot be used to monitor `ntpd`.
+
+== Real-time clock issues
+
+=== What is the real-time clock (RTC)?
+
+This is the clock which keeps the time even when your computer is turned off.
+It is used to initialise the system clock on boot. It normally does not drift
+more than few seconds per day.
+
+There are two approaches how `chronyd` can work with it. One is to use the
+`rtcsync` directive, which tells `chronyd` to enable a kernel mode which sets
+the RTC from the system clock every 11 minutes. `chronyd` itself will not touch
+the RTC. If the computer is not turned off for a long time, the RTC should
+still be close to the true time when the system clock will be initialised from
+it on the next boot.
+
+The other option is to use the `rtcfile` directive, which tells `chronyd` to
+monitor the rate at which the RTC gains or loses time. When `chronyd` is
+started with the `-s` option on the next boot, it will set the system time from
+the RTC and also compensate for the drift it has measured previously. The
+`rtcautotrim` directive can be used to keep the RTC close to the true time, but
+it is not strictly necessary if its only purpose is to set the system clock when
+`chronyd` is started on boot. See the documentation for details.
+
+=== Does `hwclock` have to be disabled?
+
+The `hwclock` program is run by default in the boot and/or shutdown
+scripts in some Linux installations. With the kernel RTC synchronisation
+(`rtcsync` directive), the RTC will be set also every 11 minutes as long as the
+system clock is synchronised. If you want to use ``chronyd``'s RTC monitoring
+(`rtcfile` directive), it is important to disable `hwclock` in the shutdown
+procedure. If you do not do that, it will overwrite the RTC with a new value, unknown
+to `chronyd`. At the next reboot, `chronyd` started with the `-s` option will
+compensate this (wrong) time with its estimate of how far the RTC has drifted
+whilst the power was off, giving a meaningless initial system time.
+
+There is no need to remove `hwclock` from the boot process, as long as `chronyd`
+is started after it has run.
+
+=== I just keep getting the `513 RTC driver not running` message
+
+For the real-time clock support to work, you need the following three
+things
+
+* an RTC in your computer
+* a Linux kernel with enabled RTC support
+* an `rtcfile` directive in your _chrony.conf_ file
+
+=== I get `Could not open /dev/rtc, Device or resource busy` in my syslog file
+
+Some other program running on the system might be using the device.
+
+=== When I start `chronyd`, the log says `Could not enable RTC interrupt : Invalid argument` (or it may say `disable`)
+
+Your real-time clock hardware might not support the required ioctl requests:
+
+* `RTC_UIE_ON`
+* `RTC_UIE_OFF`
+
+A possible solution could be to build the Linux kernel with support for software
+emulation instead; try enabling the following configuration option when building
+the Linux kernel:
+
+* `CONFIG_RTC_INTF_DEV_UIE_EMUL`
+
+=== What if my computer does not have an RTC or backup battery?
+
+In this case you can still use the `-s` option to set the system clock to the
+last modification time of the drift file, which should correspond to the system
+time when `chronyd` was previously stopped. The initial system time will be
+increasing across reboots and applications started after `chronyd` will not
+observe backward steps.
+
+== NTP-specific issues
+
+=== Can `chronyd` be driven from broadcast/multicast NTP servers?
+
+No, the broadcast/multicast client mode is not supported and there is currently
+no plan to implement it. While this mode can simplify configuration
+of clients in large networks, it is inherently less accurate and less secure
+(even with authentication) than the ordinary client/server mode.
+
+When configuring a large number of clients in a network, it is recommended to
+use the `pool` directive with a DNS name which resolves to addresses of
+multiple NTP servers. The clients will automatically replace the servers when
+they become unreachable, or otherwise unsuitable for synchronisation, with new
+servers from the pool.
+
+Even with very modest hardware, an NTP server can serve time to hundreds of
+thousands of clients using the ordinary client/server mode.
+
+=== Can `chronyd` transmit broadcast NTP packets?
+
+Yes, the `broadcast` directive can be used to enable the broadcast server mode
+to serve time to clients in the network which support the broadcast client mode
+(it is not supported in `chronyd`). Note that this mode should generally be
+avoided. See the previous question.
+
+=== Can `chronyd` keep the system clock a fixed offset away from real time?
+
+Yes. Starting from version 3.0, an offset can be specified by the `offset`
+option for all time sources in the _chrony.conf_ file.
+
+=== What happens if the network connection is dropped without using ``chronyc``'s `offline` command first?
+
+`chronyd` will keep trying to access the sources that it thinks are online, and
+it will take longer before new measurements are actually made and the clock is
+corrected when the network is connected again. If the sources were set to
+offline, `chronyd` would make new measurements immediately after issuing the
+`online` command.
+
+Unless the network connection lasts only few minutes (less than the maximum
+polling interval), the delay is usually not a problem, and it might be acceptable
+to keep all sources online all the time.
+
+=== Why is an offset measured between two computers synchronised to each another?
+
+When two computers are synchronised to each other using the client/server or
+symmetric NTP mode, there is an expectation that NTP measurements between the
+two computers made on both ends show an average offset close to zero.
+
+With `chronyd` that can be expected only when the interleaved mode is enabled
+by the `xleave` option. Otherwise, `chronyd` will use different transmit
+timestamps (e.g. daemon timestamp vs kernel timestamp) for serving time and
+synchronisation of its own clock, which will cause the other computer to
+measure a significant offset.
+
+== Operation
+
+=== What clocks does `chronyd` use?
+
+There are several different clocks used by `chronyd`:
+
+* *System clock:* software clock maintained by the kernel. It is the main clock
+  used by applications running on the computer. It is synchronised by `chronyd`
+  to its NTP clock, unless started with the *-x* option.
+* *NTP clock:* software clock (virtual) based on the system clock and internal
+  to `chronyd`. It keeps the best estimate of the true time according to the
+  configured time sources, which is served to NTP clients unless time smoothing
+  is enabled by the *smoothtime* directive. The *System time* value in the
+  `tracking` report is the current offset between the system and NTP clock.
+* *Real-time clock (RTC):* hardware clock keeping time even when the
+  computer is turned off. It is used by the kernel to initialise the system
+  clock on boot and also by `chronyd` to compensate for its measured drift if
+  configured with the `rtcfile` directive and started with the `-s` option.
+  The clock can be kept accurate only by stepping enabled by the `rtcsync` or
+  `rtcautotrim` directive.
+* *Reference clock:* hardware clock used as a time source. It is specified by
+  the `refclock` directive.
+* *NIC clock (also known as PTP hardware clock):* hardware clock timestamping
+  packets received and transmitted by a network device specified by the
+  *hwtimestamp* directive. The clock is expected to be running free. It is not
+  synchronised by `chronyd`. Its offset is tracked relative to the NTP clock in
+  order to convert the hardware timestamps.
+
+== Operating systems
+
+=== Does `chrony` support Windows?
+
+No. The `chronyc` program (the command-line client used for configuring
+`chronyd` while it is running) has been successfully built and run under
+Cygwin in the past. `chronyd` is not portable, because part of it is
+very system-dependent. It needs adapting to work with Windows'
+equivalent of the adjtimex() call, and it needs to be made to work as a
+service.
+
+=== Are there any plans to support Windows?
+
+We have no plans to do this. Anyone is welcome to pick this work up and
+contribute it back to the project.
diff --git a/doc/installation.adoc b/doc/installation.adoc
new file mode 100644
index 0000000..b683911
--- /dev/null
+++ b/doc/installation.adoc
@@ -0,0 +1,200 @@
+// This file is part of chrony
+//
+// Copyright (C) Richard P. Curnow  1997-2003
+// Copyright (C) Miroslav Lichvar  2009-2016
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of version 2 of the GNU General Public License as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+= Installation
+
+The software is distributed as source code which has to be compiled. The source
+code is supplied in the form of a gzipped tar file, which unpacks to a
+subdirectory identifying the name and version of the program.
+
+A C compiler (e.g. `gcc` or `clang`) and GNU Make are needed to build `chrony`.
+The following libraries with their development files, and programs, are needed
+to enable optional features:
+
+* pkg-config: detection of development libraries
+* Nettle, GnuTLS, NSS, or LibTomCrypt: secure hash functions (`SECHASH`)
+* libcap: dropping root privileges on Linux (`DROPROOT`)
+* libseccomp: system call filter on Linux (`SCFILTER`)
+* GnuTLS and Nettle: Network Time Security (`NTS`)
+* Editline: line editing in `chronyc` (`READLINE`)
+* timepps.h header: PPS reference clock
+* Asciidoctor: documentation in HTML format
+* Bash: test suite
+
+The following programs are needed when building `chrony` from the git
+repository instead of a released tar file:
+
+* Asciidoctor: manual pages
+* Bison: parser for chronyc settime command
+
+After unpacking the source code, change directory into it, and type
+
+----
+./configure
+----
+
+This is a shell script that automatically determines the system type. There is
+an optional parameter `--prefix`, which indicates the directory tree where the
+software should be installed. For example,
+
+----
+./configure --prefix=/opt/free
+----
+
+will install the `chronyd` daemon into `/opt/free/sbin` and the `chronyc`
+control program into `/opt/free/bin`. The default value for the prefix is
+`/usr/local`.
+
+The `configure` script assumes you want to use `gcc` as your compiler. If you
+want to use a different compiler, you can configure this way:
+
+----
+CC=cc ./configure --prefix=/opt/free
+----
+
+for Bourne-family shells, or
+
+----
+setenv CC cc
+setenv CFLAGS -O
+./configure --prefix=/opt/free
+----
+
+for C-family shells.
+
+If the software cannot (yet) be built on your system, an error message will be
+shown. Otherwise, `Makefile` will be generated.
+
+On Linux, if development files for the libcap library are available, `chronyd`
+will be built with support for dropping root privileges. On other systems no
+extra library is needed. The default user which `chronyd` should run as can be
+specified with the `--with-user` option of the `configure` script.
+
+If development files for the POSIX threads library are available, `chronyd`
+will be built with support for asynchronous resolving of hostnames specified in
+the `server`, `peer`, and `pool` directives. This allows `chronyd` operating as
+a server to respond to client requests when resolving a hostname. If you don't
+want to enable the support, specify the `--disable-asyncdns` flag to
+`configure`.
+
+If development files for the https://www.lysator.liu.se/~nisse/nettle/[Nettle],
+https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS[NSS], or
+https://www.libtom.net/LibTomCrypt/[libtomcrypt] library are available,
+`chronyd` will be built with support for other cryptographic hash functions
+than MD5, which can be used for NTP authentication with a symmetric key. If you
+don't want to enable the support, specify the `--disable-sechash` flag to
+`configure`.
+
+If development files for the editline library are available,
+`chronyc` will be built with line editing support. If you don't want this,
+specify the `--disable-readline` flag to `configure`.
+
+If a `timepps.h` header is available (e.g. from the
+http://linuxpps.org[LinuxPPS project]), `chronyd` will be built with PPS API
+reference clock driver. If the header is installed in a location that isn't
+normally searched by the compiler, you can add it to the searched locations by
+setting the `CPPFLAGS` variable to `-I/path/to/timepps`.
+
+The `--help` option can be specified to `configure` to print all options
+supported by the script.
+
+Now type
+
+----
+make
+----
+
+to build the programs.
+
+If you want to build the manual in HTML, type
+
+----
+make docs
+----
+
+Once the programs have been successfully compiled, they need to be installed in
+their target locations. This step normally needs to be performed by the
+superuser, and requires the following command to be entered.
+
+----
+make install
+----
+
+This will install the binaries and man pages.
+
+To install the HTML version of the manual, enter the command
+
+----
+make install-docs
+----
+
+Now that the software is successfully installed, the next step is to set up a
+configuration file. The default location of the file is _/etc/chrony.conf_.
+Several examples of configuration with comments are included in the examples
+directory. Suppose you want to use public NTP servers from the pool.ntp.org
+project as your time reference. A minimal useful configuration file could be
+
+----
+pool pool.ntp.org iburst
+makestep 1.0 3
+rtcsync
+----
+
+Then, `chronyd` can be run. For security reasons, it's recommended to create an
+unprivileged user for `chronyd` and specify it with the `-u` command-line
+option or the `user` directive in the configuration file, or set the default
+user with the `--with-user` configure option before building.
+
+== Support for system call filtering
+
+`chronyd` can be built with support for the Linux secure computing (seccomp)
+facility. This requires development files for the
+https://github.com/seccomp/libseccomp[libseccomp] library and the
+`--enable-scfilter` option specified to `configure`. The `-F` option of
+`chronyd` will enable a system call filter, which should significantly reduce
+the kernel attack surface and possibly prevent kernel exploits from `chronyd`
+if it is compromised.
+
+== Extra options for package builders
+
+The `configure` and `make` procedures have some extra options that may be
+useful if you are building a distribution package for `chrony`.
+
+The `--mandir=DIR` option to `configure` specifies an installation directory
+for the man pages. This overrides the `man` subdirectory of the argument to the
+`--prefix` option.
+
+----
+./configure --prefix=/usr --mandir=/usr/share/man
+----
+
+to set both options together.
+
+The final option is the `DESTDIR` option to the `make` command. For example,
+you could use the commands
+
+----
+./configure --prefix=/usr --mandir=/usr/share/man
+make all docs
+make install DESTDIR=./tmp
+cd tmp
+tar cvf - . | gzip -9 > chrony.tar.gz
+----
+
+to build a package. When untarred within the root directory, this will install
+the files to the intended final locations.
diff --git a/examples/chrony-wait.service b/examples/chrony-wait.service
new file mode 100644
index 0000000..374f633
--- /dev/null
+++ b/examples/chrony-wait.service
@@ -0,0 +1,46 @@
+[Unit]
+Description=Wait for chrony to synchronize system clock
+Documentation=man:chronyc(1)
+After=chronyd.service
+Requires=chronyd.service
+Before=time-sync.target
+Wants=time-sync.target
+
+[Service]
+Type=oneshot
+# Wait for chronyd to update the clock and the remaining
+# correction to be less than 0.1 seconds
+ExecStart=/usr/bin/chronyc -h 127.0.0.1,::1 waitsync 0 0.1 0.0 1
+# Wait for at most 3 minutes
+TimeoutStartSec=180
+RemainAfterExit=yes
+StandardOutput=null
+
+CapabilityBoundingSet=
+DevicePolicy=closed
+DynamicUser=yes
+IPAddressAllow=localhost
+IPAddressDeny=any
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+PrivateDevices=yes
+PrivateUsers=yes
+ProtectClock=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+RestrictAddressFamilies=AF_INET AF_INET6
+RestrictNamespaces=yes
+RestrictRealtime=yes
+SystemCallArchitectures=native
+SystemCallFilter=@system-service
+SystemCallFilter=~@privileged @resources
+UMask=0777
+
+[Install]
+WantedBy=multi-user.target
diff --git a/examples/chrony.conf.example1 b/examples/chrony.conf.example1
new file mode 100644
index 0000000..5e93ea7
--- /dev/null
+++ b/examples/chrony.conf.example1
@@ -0,0 +1,12 @@
+# Use public NTP servers from the pool.ntp.org project.
+pool pool.ntp.org iburst
+
+# Record the rate at which the system clock gains/losses time.
+driftfile /var/lib/chrony/drift
+
+# Allow the system clock to be stepped in the first three updates
+# if its offset is larger than 1 second.
+makestep 1.0 3
+
+# Enable kernel synchronization of the real-time clock (RTC).
+rtcsync
diff --git a/examples/chrony.conf.example2 b/examples/chrony.conf.example2
new file mode 100644
index 0000000..bf2bbdd
--- /dev/null
+++ b/examples/chrony.conf.example2
@@ -0,0 +1,47 @@
+# Use public servers from the pool.ntp.org project.
+# Please consider joining the pool (https://www.pool.ntp.org/join.html).
+pool pool.ntp.org iburst
+
+# Record the rate at which the system clock gains/losses time.
+driftfile /var/lib/chrony/drift
+
+# Allow the system clock to be stepped in the first three updates
+# if its offset is larger than 1 second.
+makestep 1.0 3
+
+# Enable kernel synchronization of the real-time clock (RTC).
+rtcsync
+
+# Enable hardware timestamping on all interfaces that support it.
+#hwtimestamp *
+
+# Increase the minimum number of selectable sources required to adjust
+# the system clock.
+#minsources 2
+
+# Allow NTP client access from local network.
+#allow 192.168.0.0/16
+
+# Serve time even if not synchronized to a time source.
+#local stratum 10
+
+# Require authentication (nts or key option) for all NTP sources.
+#authselectmode require
+
+# Specify file containing keys for NTP authentication.
+#keyfile /etc/chrony.keys
+
+# Save NTS keys and cookies.
+ntsdumpdir /var/lib/chrony
+
+# Insert/delete leap seconds by slewing instead of stepping.
+#leapsecmode slew
+
+# Get TAI-UTC offset and leap seconds from the system tz database.
+#leapsectz right/UTC
+
+# Specify directory for log files.
+logdir /var/log/chrony
+
+# Select which information is logged.
+#log measurements statistics tracking
diff --git a/examples/chrony.conf.example3 b/examples/chrony.conf.example3
new file mode 100644
index 0000000..4e3e3a8
--- /dev/null
+++ b/examples/chrony.conf.example3
@@ -0,0 +1,334 @@
+#######################################################################
+#
+# This is an example chrony configuration file.  You should copy it to
+# /etc/chrony.conf after uncommenting and editing the options that you
+# want to enable.  The more obscure options are not included.  Refer
+# to the documentation for these.
+#
+#######################################################################
+### COMMENTS
+# Any of the following lines are comments (you have a choice of
+# comment start character):
+# a comment
+% a comment
+! a comment
+; a comment
+#
+# Below, the '!' form is used for lines that you might want to
+# uncomment and edit to make your own chrony.conf file.
+#
+#######################################################################
+#######################################################################
+### SPECIFY YOUR NTP SERVERS
+# Most computers using chrony will send measurement requests to one or
+# more 'NTP servers'.  You will probably find that your Internet Service
+# Provider or company have one or more NTP servers that you can specify.
+# Failing that, there are a lot of public NTP servers.  There is a list
+# you can access at http://support.ntp.org/bin/view/Servers/WebHome or
+# you can use servers from the pool.ntp.org project.
+
+! server foo.example.net iburst
+! server bar.example.net iburst
+! server baz.example.net iburst
+
+! pool pool.ntp.org iburst
+ 
+#######################################################################
+### AVOIDING POTENTIALLY BOGUS CHANGES TO YOUR CLOCK
+#
+# To avoid changes being made to your computer's gain/loss compensation
+# when the measurement history is too erratic, you might want to enable
+# one of the following lines.  The first seems good with servers on the
+# Internet, the second seems OK for a LAN environment.
+
+! maxupdateskew 100
+! maxupdateskew 5
+
+# If you want to increase the minimum number of selectable sources
+# required to update the system clock in order to make the
+# synchronisation more reliable, uncomment (and edit) the following
+# line.
+
+! minsources 2
+
+# If your computer has a good stable clock (e.g. it is not a virtual
+# machine), you might also want to reduce the maximum assumed drift
+# (frequency error) of the clock (the value is specified in ppm).
+
+! maxdrift 100
+
+# By default, chronyd allows synchronisation to an unauthenticated NTP
+# source (i.e. specified without the nts and key options) if it agrees with
+# a majority of authenticated NTP sources, or if no authenticated source is
+# specified.  If you don't want chronyd to ever synchronise to an
+# unauthenticated NTP source, uncomment the first from the following lines.
+# If you don't want to synchronise to an unauthenticated NTP source only
+# when an authenticated source is specified, uncomment the second line.
+# If you want chronyd to ignore authentication in the source selection,
+# uncomment the third line.
+
+! authselectmode require
+! authselectmode prefer
+! authselectmode ignore
+
+#######################################################################
+### FILENAMES ETC
+# Chrony likes to keep information about your computer's clock in files.
+# The 'driftfile' stores the computer's clock gain/loss rate in parts
+# per million.  When chronyd starts, the system clock can be tuned
+# immediately so that it doesn't gain or lose any more time.  You
+# generally want this, so it is uncommented.
+
+driftfile /var/lib/chrony/drift
+
+# If you want to enable NTP authentication with symmetric keys, you will need
+# to uncomment the following line and edit the file to set up the keys.
+
+! keyfile /etc/chrony.keys
+
+# If you specify an NTP server with the nts option to enable authentication
+# with the Network Time Security (NTS) mechanism, or enable server NTS with
+# the ntsservercert and ntsserverkey directives below, the following line will
+# allow the client/server to save the NTS keys and cookies in order to reduce
+# the number of key establishments (NTS-KE sessions).
+
+ntsdumpdir /var/lib/chrony
+
+# If chronyd is configured to act as an NTP server and you want to enable NTS
+# for its clients, you will need a TLS certificate and private key.  Uncomment
+# and edit the following lines to specify the locations of the certificate and
+# key.
+
+! ntsservercert /etc/.../foo.example.net.crt
+! ntsserverkey /etc/.../foo.example.net.key
+
+# chronyd can save the measurement history for the servers to files when
+# it exits.  This is useful in 2 situations:
+#
+# 1. If you stop chronyd and restart it with the '-r' option (e.g. after
+# an upgrade), the old measurements will still be relevant when chronyd
+# is restarted.  This will reduce the time needed to get accurate
+# gain/loss measurements.
+#
+# 2. On Linux, if you use the RTC support and start chronyd with
+# '-r -s' on bootup, measurements from the last boot will still be
+# useful (the real time clock is used to 'flywheel' chronyd between
+# boots).
+#
+# Uncomment the following line to use this.
+
+! dumpdir /var/lib/chrony
+
+# chronyd writes its process ID to a file.  If you try to start a second
+# copy of chronyd, it will detect that the process named in the file is
+# still running and bail out.  If you want to change the path to the PID
+# file, uncomment this line and edit it.  The default path is shown.
+
+! pidfile /var/run/chrony/chronyd.pid
+
+# If the system timezone database is kept up to date and includes the
+# right/UTC timezone, chronyd can use it to determine the current
+# TAI-UTC offset and when will the next leap second occur.
+
+! leapsectz right/UTC
+
+#######################################################################
+### INITIAL CLOCK CORRECTION
+# This option is useful to quickly correct the clock on start if it's
+# off by a large amount.  The value '1.0' means that if the error is less
+# than 1 second, it will be gradually removed by speeding up or slowing
+# down your computer's clock until it is correct.  If the error is above
+# 1 second, an immediate time jump will be applied to correct it.  The
+# value '3' means the step is allowed only in the first three updates of
+# the clock.  Some software can get upset if the system clock jumps
+# (especially backwards), so be careful!
+
+! makestep 1.0 3
+
+#######################################################################
+### LEAP SECONDS
+# A leap second is an occasional one-second correction of the UTC
+# time scale.  By default, chronyd tells the kernel to insert/delete
+# the leap second, which makes a backward/forward step to correct the
+# clock for it.  As with the makestep directive, this jump can upset
+# some applications.  If you prefer chronyd to make a gradual
+# correction, causing the clock to be off for a longer time, uncomment
+# the following line.
+
+! leapsecmode slew
+
+#######################################################################
+### LOGGING
+# If you want to log information about the time measurements chronyd has
+# gathered, you might want to enable the following lines.  You probably
+# only need this if you really enjoy looking at the logs, you want to
+# produce some graphs of your system's timekeeping performance, or you
+# need help in debugging a problem.
+
+! logdir /var/log/chrony
+! log measurements statistics tracking
+
+# If you have real time clock support enabled (see below), you might want
+# this line instead:
+
+! log measurements statistics tracking rtc
+
+#######################################################################
+### ACTING AS AN NTP SERVER
+# You might want the computer to be an NTP server for other computers.
+#
+# By default, chronyd does not allow any clients to access it.  You need
+# to explicitly enable access using 'allow' and 'deny' directives.
+#
+# e.g. to enable client access from the 192.168.*.* class B subnet,
+
+! allow 192.168/16
+
+# .. but disallow the 192.168.100.* subnet of that,
+
+! deny 192.168.100/24
+
+# You can have as many allow and deny directives as you need.  The order
+# is unimportant.
+
+# If you want to present your computer's time for others to synchronise
+# with, even if you don't seem to be synchronised to any NTP servers
+# yourself, enable the following line.  The value 10 may be varied
+# between 1 and 15.  You should avoid small values because you will look
+# like a real NTP server.  The value 10 means that you appear to be 10
+# NTP 'hops' away from an authoritative source (atomic clock, GPS
+# receiver, radio clock etc).
+
+! local stratum 10
+
+# Normally, chronyd will keep track of how many times each client
+# machine accesses it.  The information can be accessed by the 'clients'
+# command of chronyc.  You can disable this facility by uncommenting the
+# following line.  This will save a bit of memory if you have many
+# clients and it will also disable support for the interleaved mode.
+
+! noclientlog
+
+# The clientlog size is limited to 512KB by default.  If you have many
+# clients, you might want to increase the limit.
+
+! clientloglimit 4194304
+
+# By default, chronyd tries to respond to all valid NTP requests from
+# allowed addresses.  If you want to limit the response rate for NTP
+# clients that are sending requests too frequently, uncomment and edit
+# the following line.
+
+! ratelimit interval 3 burst 8
+
+#######################################################################
+### REPORTING BIG CLOCK CHANGES
+# Perhaps you want to know if chronyd suddenly detects any large error
+# in your computer's clock.  This might indicate a fault or a problem
+# with the server(s) you are using, for example.
+#
+# The next option causes a message to be written to syslog when chronyd
+# has to correct an error above 0.5 seconds (you can use any amount you
+# like).
+
+! logchange 0.5
+
+# The next option will send email to the named person when chronyd has
+# to correct an error above 0.5 seconds.  (If you need to send mail to
+# several people, you need to set up a mailing list or sendmail alias
+# for them and use the address of that.)
+
+! mailonchange wibble@foo.example.net 0.5
+
+#######################################################################
+### COMMAND ACCESS
+# The program chronyc is used to show the current operation of chronyd
+# and to change parts of its configuration whilst it is running.
+
+# By default chronyd binds to the loopback interface.  Uncomment the
+# following lines to allow receiving command packets from remote hosts.
+
+! bindcmdaddress 0.0.0.0
+! bindcmdaddress ::
+
+# Normally, chronyd will only allow connections from chronyc on the same
+# machine as itself.  This is for security.  If you have a subnet
+# 192.168.*.* and you want to be able to use chronyc from any machine on
+# it, you could uncomment the following line.  (Edit this to your own
+# situation.)
+
+! cmdallow 192.168/16
+
+# You can add as many 'cmdallow' and 'cmddeny' lines as you like.  The
+# syntax and meaning is the same as for 'allow' and 'deny', except that
+# 'cmdallow' and 'cmddeny' control access to the chronyd's command port.
+
+# Rate limiting can be enabled also for command packets.  (Note,
+# commands from localhost are never limited.)
+
+! cmdratelimit interval -4 burst 16
+
+#######################################################################
+### HARDWARE TIMESTAMPING
+# On Linux, if the network interface controller and its driver support
+# hardware timestamping, it can significantly improve the accuracy of
+# synchronisation. It can be enabled on specified interfaces only, or it
+# can be enabled on all interfaces that support it.
+
+! hwtimestamp eth0
+! hwtimestamp *
+
+#######################################################################
+### REAL TIME CLOCK
+# chronyd can characterise the system's real-time clock.  This is the
+# clock that keeps running when the power is turned off, so that the
+# machine knows the approximate time when it boots again.  The error at
+# a particular epoch and gain/loss rate can be written to a file and
+# used later by chronyd when it is started with the '-s' option.
+#
+# You need to have 'enhanced RTC support' compiled into your Linux
+# kernel.  (Note, these options apply only to Linux.)
+
+! rtcfile /var/lib/chrony/rtc
+
+# Your RTC can be set to keep Universal Coordinated Time (UTC) or local
+# time.  (Local time means UTC +/- the effect of your timezone.)  If you
+# use UTC, chronyd will function correctly even if the computer is off
+# at the epoch when you enter or leave summer time (aka daylight saving
+# time).  However, if you dual boot your system with Microsoft Windows,
+# that will work better if your RTC maintains local time.  You take your
+# pick!
+
+! rtconutc
+
+# By default chronyd assumes that the enhanced RTC device is accessed as
+# /dev/rtc.  If it's accessed somewhere else on your system (e.g. you're
+# using devfs), uncomment and edit the following line.
+
+! rtcdevice /dev/misc/rtc
+
+# Alternatively, if not using the -s option, this directive can be used
+# to enable a mode in which the RTC is periodically set to the system
+# time, with no tracking of its drift.
+
+! rtcsync
+
+#######################################################################
+### REAL TIME SCHEDULER
+# This directive tells chronyd to use the real-time FIFO scheduler with the
+# specified priority (which must be between 0 and 100).  This should result
+# in reduced latency.  You don't need it unless you really have a requirement
+# for extreme clock stability.  Works only on Linux.  Note that the "-P"
+# command-line switch will override this.
+
+! sched_priority 1
+
+#######################################################################
+### LOCKING CHRONYD INTO RAM
+# This directive tells chronyd to use the mlockall() syscall to lock itself
+# into RAM so that it will never be paged out.  This should result in reduced
+# latency.  You don't need it unless you really have a requirement
+# for extreme clock stability.  Works only on Linux.  Note that the "-m"
+# command-line switch will also enable this feature.
+
+! lock_all
diff --git a/examples/chrony.keys.example b/examples/chrony.keys.example
new file mode 100644
index 0000000..05e720c
--- /dev/null
+++ b/examples/chrony.keys.example
@@ -0,0 +1,15 @@
+# This is an example chrony keys file.  It enables authentication of NTP
+# packets with symmetric keys when its location is specified by the keyfile
+# directive in chrony.conf(5).  It should be readable only by root and the
+# user under which chronyd is running.
+#
+# Don't use the example keys!  It's recommended to generate random keys using
+# the chronyc keygen command.
+
+# Examples of valid keys:
+
+#1 MD5 AVeryLongAndRandomPassword
+#2 MD5 HEX:12114855C7931009B4049EF3EFC48A139C3F989F
+#3 SHA1 HEX:B2159C05D6A219673A3B7E896B6DE07F6A440995
+#4 AES128 HEX:2DA837C4B6573748CA692B8C828E4891
+#5 AES256 HEX:2666B8099BFF2D5BA20876121788ED24D2BE59111B8FFB562F0F56AE6EC7246E
diff --git a/examples/chrony.logrotate b/examples/chrony.logrotate
new file mode 100644
index 0000000..2823a1a
--- /dev/null
+++ b/examples/chrony.logrotate
@@ -0,0 +1,8 @@
+/var/log/chrony/*.log {
+    missingok
+    nocreate
+    sharedscripts
+    postrotate
+        /usr/bin/chronyc cyclelogs > /dev/null 2>&1 || true
+    endscript
+}
diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
new file mode 100644
index 0000000..547ce83
--- /dev/null
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -0,0 +1,49 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher script for chronyd to update
+# its NTP sources with servers from DHCP options passed by NetworkManager
+# in the DHCP4_NTP_SERVERS and DHCP6_DHCP6_NTP_SERVERS environment variables.
+
+export LC_ALL=C
+
+interface=$1
+action=$2
+
+chronyc=/usr/bin/chronyc
+server_options=iburst
+server_dir=/var/run/chrony-dhcp
+
+dhcp_server_file=$server_dir/$interface.sources
+dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
+
+add_servers_from_dhcp() {
+    rm -f "$dhcp_server_file"
+    for server in $dhcp_ntp_servers; do
+        # Check for invalid characters (from the DHCPv6 NTP FQDN suboption)
+        len1=$(printf '%s' "$server" | wc -c)
+        len2=$(printf '%s' "$server" | tr -d -c 'A-Za-z0-9:.-' | wc -c)
+        if [ "$len1" -ne "$len2" ] || [ "$len2" -lt 1 ] || [ "$len2" -gt 255 ]; then
+          continue
+        fi
+
+        printf 'server %s %s\n' "$server" "$server_options" >> "$dhcp_server_file"
+    done
+    $chronyc reload sources > /dev/null 2>&1 || :
+}
+
+clear_servers_from_dhcp() {
+    if [ -f "$dhcp_server_file" ]; then
+        rm -f "$dhcp_server_file"
+        $chronyc reload sources > /dev/null 2>&1 || :
+    fi
+}
+
+mkdir -p $server_dir
+
+case "$action" in
+    up|dhcp4-change|dhcp6-change)
+        add_servers_from_dhcp;;
+    down)
+        clear_servers_from_dhcp;;
+esac
+
+exit 0
diff --git a/examples/chrony.nm-dispatcher.onoffline b/examples/chrony.nm-dispatcher.onoffline
new file mode 100644
index 0000000..18f5c3f
--- /dev/null
+++ b/examples/chrony.nm-dispatcher.onoffline
@@ -0,0 +1,29 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher / networkd-dispatcher script for
+# chronyd to set its NTP sources online or offline when a network interface
+# is configured or removed
+
+export LC_ALL=C
+
+chronyc=/usr/bin/chronyc
+
+# For NetworkManager consider only selected events
+if [ $# -ge 2 ]; then
+    case "$2" in
+        up|down|connectivity-change)
+            ;;
+        dhcp4-change|dhcp6-change)
+            # Actions "up" and "connectivity-change" in some cases do not
+            # guarantee that the interface has a route (e.g. a bond).
+            # dhcp(x)-change handles at least cases that use DHCP.
+            ;;
+        *)
+            exit 0;;
+    esac
+fi
+
+# Note: for networkd-dispatcher routable.d ~= on and off.d ~= off
+
+$chronyc onoffline > /dev/null 2>&1
+
+exit 0
diff --git a/examples/chronyd-restricted.service b/examples/chronyd-restricted.service
new file mode 100644
index 0000000..30ba7d9
--- /dev/null
+++ b/examples/chronyd-restricted.service
@@ -0,0 +1,58 @@
+# This is a more restricted version of the chronyd service intended for
+# minimal NTP/NTS client configurations. The daemon is started without root
+# privileges and is allowed to write only to its own runtime, state, and log
+# directories. It cannot bind to privileged ports in order to operate as an
+# NTP server, or provide monitoring access over IPv4/IPv6. It cannot use
+# reference clocks, HW timestamping, RTC tracking, and other features.
+[Unit]
+Description=NTP client (restricted)
+Documentation=man:chronyd(8) man:chrony.conf(5)
+After=chronyd.service ntpdate.service sntp.service ntpd.service
+Conflicts=chronyd.service ntpd.service systemd-timesyncd.service
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/sysconfig/chronyd
+ExecStart=/usr/sbin/chronyd -U $OPTIONS
+
+User=chrony
+LogsDirectory=chrony
+LogsDirectoryMode=0750
+RuntimeDirectory=chrony
+RuntimeDirectoryMode=0750
+RuntimeDirectoryPreserve=restart
+StateDirectory=chrony
+StateDirectoryMode=0750
+
+AmbientCapabilities=CAP_SYS_TIME
+CapabilityBoundingSet=CAP_SYS_TIME
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateDevices=yes
+PrivateTmp=yes
+# This breaks adjtimex()
+#PrivateUsers=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+RemoveIPC=yes
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictRealtime=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io
+SystemCallFilter=~@reboot @resources @swap
+UMask=0077
+
+[Install]
+WantedBy=multi-user.target
diff --git a/examples/chronyd.service b/examples/chronyd.service
new file mode 100644
index 0000000..a42eb92
--- /dev/null
+++ b/examples/chronyd.service
@@ -0,0 +1,48 @@
+[Unit]
+Description=NTP client/server
+Documentation=man:chronyd(8) man:chrony.conf(5)
+After=ntpdate.service sntp.service ntpd.service
+Conflicts=ntpd.service systemd-timesyncd.service
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/sysconfig/chronyd
+ExecStart=/usr/sbin/chronyd $OPTIONS
+
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD CAP_SYS_ADMIN
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
+DeviceAllow=char-pps rw
+DeviceAllow=char-ptp rw
+DeviceAllow=char-rtc rw
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+ReadWritePaths=/run /var/lib/chrony -/var/log
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap
+
+# Adjust restrictions for /usr/sbin/sendmail (mailonchange directive)
+NoNewPrivileges=no
+ReadWritePaths=-/var/spool
+RestrictAddressFamilies=AF_NETLINK
+
+[Install]
+WantedBy=multi-user.target
diff --git a/getdate.c b/getdate.c
new file mode 100644
index 0000000..65d1b99
--- /dev/null
+++ b/getdate.c
@@ -0,0 +1,2601 @@
+/* A Bison parser, made by GNU Bison 3.8.2.  */
+
+/* Bison implementation for Yacc-like parsers in C
+
+   Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2021 Free Software Foundation,
+   Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* As a special exception, you may create a larger work that contains
+   part or all of the Bison parser skeleton and distribute that work
+   under terms of your choice, so long as that work isn't itself a
+   parser generator using the skeleton or a modified version thereof
+   as a parser skeleton.  Alternatively, if you modify or redistribute
+   the parser skeleton itself, you may (at your option) remove this
+   special exception, which will cause the skeleton and the resulting
+   Bison output files to be licensed under the GNU General Public
+   License without this special exception.
+
+   This special exception was added by the Free Software Foundation in
+   version 2.2 of Bison.  */
+
+/* C LALR(1) parser skeleton written by Richard Stallman, by
+   simplifying the original so-called "semantic" parser.  */
+
+/* DO NOT RELY ON FEATURES THAT ARE NOT DOCUMENTED in the manual,
+   especially those whose name start with YY_ or yy_.  They are
+   private implementation details that can be changed or removed.  */
+
+/* All symbols defined below should begin with yy or YY, to avoid
+   infringing on user name space.  This should be done even for local
+   variables, as they might otherwise be expanded by user macros.
+   There are some unavoidable exceptions within include files to
+   define necessary library symbols; they are noted "INFRINGES ON
+   USER NAME SPACE" below.  */
+
+/* Identify Bison output, and Bison version.  */
+#define YYBISON 30802
+
+/* Bison version string.  */
+#define YYBISON_VERSION "3.8.2"
+
+/* Skeleton name.  */
+#define YYSKELETON_NAME "yacc.c"
+
+/* Pure parsers.  */
+#define YYPURE 0
+
+/* Push parsers.  */
+#define YYPUSH 0
+
+/* Pull parsers.  */
+#define YYPULL 1
+
+
+
+
+/* First part of user prologue.  */
+#line 1 "getdate.y"
+
+/*
+**  Originally written by Steven M. Bellovin <smb@research.att.com> while
+**  at the University of North Carolina at Chapel Hill.  Later tweaked by
+**  a couple of people on Usenet.  Completely overhauled by Rich $alz
+**  <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
+**
+**  This code is in the public domain and has no copyright.
+*/
+
+#include "config.h"
+
+/* Since the code of getdate.y is not included in the Emacs executable
+   itself, there is no need to #define static in this file.  Even if
+   the code were included in the Emacs executable, it probably
+   wouldn't do any harm to #undef it here; this will only cause
+   problems if we try to write to a static variable, which I don't
+   think this code needs to do.  */
+#ifdef emacs
+# undef static
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+
+#if HAVE_STDLIB_H
+# include <stdlib.h> /* for `free'; used by Bison 1.27 */
+#endif
+
+#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+#endif
+
+#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
+#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
+#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c))
+#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+
+/* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
+   only '0' through '9' are digits.  Prefer ISDIGIT to ISDIGIT_LOCALE unless
+   it's important to use the locale's definition of `digit' even when the
+   host does not conform to Posix.  */
+#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
+
+#if defined (STDC_HEADERS) || defined (USG)
+# include <string.h>
+#endif
+
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
+# define __attribute__(x)
+#endif
+
+#ifndef ATTRIBUTE_UNUSED
+# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#endif
+
+/* Some old versions of bison generate parsers that use bcopy.
+   That loses on systems that don't provide the function, so we have
+   to redefine it here.  */
+#if !defined (HAVE_BCOPY) && defined (HAVE_MEMCPY) && !defined (bcopy)
+# define bcopy(from, to, len) memcpy ((to), (from), (len))
+#endif
+
+/* Remap normal yacc parser interface names (yyparse, yylex, yyerror, etc),
+   as well as gratuitiously global symbol names, so we can have multiple
+   yacc generated parsers in the same program.  Note that these are only
+   the variables produced by yacc.  If other parser generators (bison,
+   byacc, etc) produce additional global names that conflict at link time,
+   then those parser generators need to be fixed instead of adding those
+   names to this list. */
+
+#define yymaxdepth gd_maxdepth
+#define yyparse gd_parse
+#define yylex   gd_lex
+#define yyerror gd_error
+#define yylval  gd_lval
+#define yychar  gd_char
+#define yydebug gd_debug
+#define yypact  gd_pact
+#define yyr1    gd_r1
+#define yyr2    gd_r2
+#define yydef   gd_def
+#define yychk   gd_chk
+#define yypgo   gd_pgo
+#define yyact   gd_act
+#define yyexca  gd_exca
+#define yyerrflag gd_errflag
+#define yynerrs gd_nerrs
+#define yyps    gd_ps
+#define yypv    gd_pv
+#define yys     gd_s
+#define yy_yys  gd_yys
+#define yystate gd_state
+#define yytmp   gd_tmp
+#define yyv     gd_v
+#define yy_yyv  gd_yyv
+#define yyval   gd_val
+#define yylloc  gd_lloc
+#define yyreds  gd_reds          /* With YYDEBUG defined */
+#define yytoks  gd_toks          /* With YYDEBUG defined */
+#define yylhs   gd_yylhs
+#define yylen   gd_yylen
+#define yydefred gd_yydefred
+#define yydgoto gd_yydgoto
+#define yysindex gd_yysindex
+#define yyrindex gd_yyrindex
+#define yygindex gd_yygindex
+#define yytable  gd_yytable
+#define yycheck  gd_yycheck
+
+static int yylex (void);
+static int yyerror (char *s);
+
+#define EPOCH		1970
+#define HOUR(x)		((x) * 60)
+
+#define MAX_BUFF_LEN    128   /* size of buffer to read the date into */
+
+/*
+**  An entry in the lexical lookup table.
+*/
+typedef struct _TABLE {
+    const char	*name;
+    int		type;
+    int		value;
+} TABLE;
+
+
+/*
+**  Meridian:  am, pm, or 24-hour style.
+*/
+typedef enum _MERIDIAN {
+    MERam, MERpm, MER24
+} MERIDIAN;
+
+
+/*
+**  Global variables.  We could get rid of most of these by using a good
+**  union as the yacc stack.  (This routine was originally written before
+**  yacc had the %union construct.)  Maybe someday; right now we only use
+**  the %union very rarely.
+*/
+static const char	*yyInput;
+static int	yyDayOrdinal;
+static int	yyDayNumber;
+static int	yyHaveDate;
+static int	yyHaveDay;
+static int	yyHaveRel;
+static int	yyHaveTime;
+static int	yyHaveZone;
+static int	yyTimezone;
+static int	yyDay;
+static int	yyHour;
+static int	yyMinutes;
+static int	yyMonth;
+static int	yySeconds;
+static int	yyYear;
+static MERIDIAN	yyMeridian;
+static int	yyRelDay;
+static int	yyRelHour;
+static int	yyRelMinutes;
+static int	yyRelMonth;
+static int	yyRelSeconds;
+static int	yyRelYear;
+
+
+#line 244 "getdate.c"
+
+# ifndef YY_CAST
+#  ifdef __cplusplus
+#   define YY_CAST(Type, Val) static_cast<Type> (Val)
+#   define YY_REINTERPRET_CAST(Type, Val) reinterpret_cast<Type> (Val)
+#  else
+#   define YY_CAST(Type, Val) ((Type) (Val))
+#   define YY_REINTERPRET_CAST(Type, Val) ((Type) (Val))
+#  endif
+# endif
+# ifndef YY_NULLPTR
+#  if defined __cplusplus
+#   if 201103L <= __cplusplus
+#    define YY_NULLPTR nullptr
+#   else
+#    define YY_NULLPTR 0
+#   endif
+#  else
+#   define YY_NULLPTR ((void*)0)
+#  endif
+# endif
+
+
+/* Debug traces.  */
+#ifndef YYDEBUG
+# define YYDEBUG 0
+#endif
+#if YYDEBUG
+extern int yydebug;
+#endif
+
+/* Token kinds.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+  enum yytokentype
+  {
+    YYEMPTY = -2,
+    YYEOF = 0,                     /* "end of file"  */
+    YYerror = 256,                 /* error  */
+    YYUNDEF = 257,                 /* "invalid token"  */
+    tAGO = 258,                    /* tAGO  */
+    tDAY = 259,                    /* tDAY  */
+    tDAY_UNIT = 260,               /* tDAY_UNIT  */
+    tDAYZONE = 261,                /* tDAYZONE  */
+    tDST = 262,                    /* tDST  */
+    tHOUR_UNIT = 263,              /* tHOUR_UNIT  */
+    tID = 264,                     /* tID  */
+    tMERIDIAN = 265,               /* tMERIDIAN  */
+    tMINUTE_UNIT = 266,            /* tMINUTE_UNIT  */
+    tMONTH = 267,                  /* tMONTH  */
+    tMONTH_UNIT = 268,             /* tMONTH_UNIT  */
+    tSEC_UNIT = 269,               /* tSEC_UNIT  */
+    tSNUMBER = 270,                /* tSNUMBER  */
+    tUNUMBER = 271,                /* tUNUMBER  */
+    tYEAR_UNIT = 272,              /* tYEAR_UNIT  */
+    tZONE = 273                    /* tZONE  */
+  };
+  typedef enum yytokentype yytoken_kind_t;
+#endif
+
+/* Value type.  */
+#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
+union YYSTYPE
+{
+#line 177 "getdate.y"
+
+    int			Number;
+    enum _MERIDIAN	Meridian;
+
+#line 314 "getdate.c"
+
+};
+typedef union YYSTYPE YYSTYPE;
+# define YYSTYPE_IS_TRIVIAL 1
+# define YYSTYPE_IS_DECLARED 1
+#endif
+
+
+extern YYSTYPE yylval;
+
+
+int yyparse (void);
+
+
+
+/* Symbol kind.  */
+enum yysymbol_kind_t
+{
+  YYSYMBOL_YYEMPTY = -2,
+  YYSYMBOL_YYEOF = 0,                      /* "end of file"  */
+  YYSYMBOL_YYerror = 1,                    /* error  */
+  YYSYMBOL_YYUNDEF = 2,                    /* "invalid token"  */
+  YYSYMBOL_tAGO = 3,                       /* tAGO  */
+  YYSYMBOL_tDAY = 4,                       /* tDAY  */
+  YYSYMBOL_tDAY_UNIT = 5,                  /* tDAY_UNIT  */
+  YYSYMBOL_tDAYZONE = 6,                   /* tDAYZONE  */
+  YYSYMBOL_tDST = 7,                       /* tDST  */
+  YYSYMBOL_tHOUR_UNIT = 8,                 /* tHOUR_UNIT  */
+  YYSYMBOL_tID = 9,                        /* tID  */
+  YYSYMBOL_tMERIDIAN = 10,                 /* tMERIDIAN  */
+  YYSYMBOL_tMINUTE_UNIT = 11,              /* tMINUTE_UNIT  */
+  YYSYMBOL_tMONTH = 12,                    /* tMONTH  */
+  YYSYMBOL_tMONTH_UNIT = 13,               /* tMONTH_UNIT  */
+  YYSYMBOL_tSEC_UNIT = 14,                 /* tSEC_UNIT  */
+  YYSYMBOL_tSNUMBER = 15,                  /* tSNUMBER  */
+  YYSYMBOL_tUNUMBER = 16,                  /* tUNUMBER  */
+  YYSYMBOL_tYEAR_UNIT = 17,                /* tYEAR_UNIT  */
+  YYSYMBOL_tZONE = 18,                     /* tZONE  */
+  YYSYMBOL_19_ = 19,                       /* ':'  */
+  YYSYMBOL_20_ = 20,                       /* ','  */
+  YYSYMBOL_21_ = 21,                       /* '/'  */
+  YYSYMBOL_YYACCEPT = 22,                  /* $accept  */
+  YYSYMBOL_spec = 23,                      /* spec  */
+  YYSYMBOL_item = 24,                      /* item  */
+  YYSYMBOL_time = 25,                      /* time  */
+  YYSYMBOL_zone = 26,                      /* zone  */
+  YYSYMBOL_day = 27,                       /* day  */
+  YYSYMBOL_date = 28,                      /* date  */
+  YYSYMBOL_rel = 29,                       /* rel  */
+  YYSYMBOL_relunit = 30,                   /* relunit  */
+  YYSYMBOL_number = 31,                    /* number  */
+  YYSYMBOL_o_merid = 32                    /* o_merid  */
+};
+typedef enum yysymbol_kind_t yysymbol_kind_t;
+
+
+
+
+#ifdef short
+# undef short
+#endif
+
+/* On compilers that do not define __PTRDIFF_MAX__ etc., make sure
+   <limits.h> and (if available) <stdint.h> are included
+   so that the code can choose integer types of a good width.  */
+
+#ifndef __PTRDIFF_MAX__
+# include <limits.h> /* INFRINGES ON USER NAME SPACE */
+# if defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
+#  include <stdint.h> /* INFRINGES ON USER NAME SPACE */
+#  define YY_STDINT_H
+# endif
+#endif
+
+/* Narrow types that promote to a signed type and that can represent a
+   signed or unsigned integer of at least N bits.  In tables they can
+   save space and decrease cache pressure.  Promoting to a signed type
+   helps avoid bugs in integer arithmetic.  */
+
+#ifdef __INT_LEAST8_MAX__
+typedef __INT_LEAST8_TYPE__ yytype_int8;
+#elif defined YY_STDINT_H
+typedef int_least8_t yytype_int8;
+#else
+typedef signed char yytype_int8;
+#endif
+
+#ifdef __INT_LEAST16_MAX__
+typedef __INT_LEAST16_TYPE__ yytype_int16;
+#elif defined YY_STDINT_H
+typedef int_least16_t yytype_int16;
+#else
+typedef short yytype_int16;
+#endif
+
+/* Work around bug in HP-UX 11.23, which defines these macros
+   incorrectly for preprocessor constants.  This workaround can likely
+   be removed in 2023, as HPE has promised support for HP-UX 11.23
+   (aka HP-UX 11i v2) only through the end of 2022; see Table 2 of
+   <https://h20195.www2.hpe.com/V2/getpdf.aspx/4AA4-7673ENW.pdf>.  */
+#ifdef __hpux
+# undef UINT_LEAST8_MAX
+# undef UINT_LEAST16_MAX
+# define UINT_LEAST8_MAX 255
+# define UINT_LEAST16_MAX 65535
+#endif
+
+#if defined __UINT_LEAST8_MAX__ && __UINT_LEAST8_MAX__ <= __INT_MAX__
+typedef __UINT_LEAST8_TYPE__ yytype_uint8;
+#elif (!defined __UINT_LEAST8_MAX__ && defined YY_STDINT_H \
+       && UINT_LEAST8_MAX <= INT_MAX)
+typedef uint_least8_t yytype_uint8;
+#elif !defined __UINT_LEAST8_MAX__ && UCHAR_MAX <= INT_MAX
+typedef unsigned char yytype_uint8;
+#else
+typedef short yytype_uint8;
+#endif
+
+#if defined __UINT_LEAST16_MAX__ && __UINT_LEAST16_MAX__ <= __INT_MAX__
+typedef __UINT_LEAST16_TYPE__ yytype_uint16;
+#elif (!defined __UINT_LEAST16_MAX__ && defined YY_STDINT_H \
+       && UINT_LEAST16_MAX <= INT_MAX)
+typedef uint_least16_t yytype_uint16;
+#elif !defined __UINT_LEAST16_MAX__ && USHRT_MAX <= INT_MAX
+typedef unsigned short yytype_uint16;
+#else
+typedef int yytype_uint16;
+#endif
+
+#ifndef YYPTRDIFF_T
+# if defined __PTRDIFF_TYPE__ && defined __PTRDIFF_MAX__
+#  define YYPTRDIFF_T __PTRDIFF_TYPE__
+#  define YYPTRDIFF_MAXIMUM __PTRDIFF_MAX__
+# elif defined PTRDIFF_MAX
+#  ifndef ptrdiff_t
+#   include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  endif
+#  define YYPTRDIFF_T ptrdiff_t
+#  define YYPTRDIFF_MAXIMUM PTRDIFF_MAX
+# else
+#  define YYPTRDIFF_T long
+#  define YYPTRDIFF_MAXIMUM LONG_MAX
+# endif
+#endif
+
+#ifndef YYSIZE_T
+# ifdef __SIZE_TYPE__
+#  define YYSIZE_T __SIZE_TYPE__
+# elif defined size_t
+#  define YYSIZE_T size_t
+# elif defined __STDC_VERSION__ && 199901 <= __STDC_VERSION__
+#  include <stddef.h> /* INFRINGES ON USER NAME SPACE */
+#  define YYSIZE_T size_t
+# else
+#  define YYSIZE_T unsigned
+# endif
+#endif
+
+#define YYSIZE_MAXIMUM                                  \
+  YY_CAST (YYPTRDIFF_T,                                 \
+           (YYPTRDIFF_MAXIMUM < YY_CAST (YYSIZE_T, -1)  \
+            ? YYPTRDIFF_MAXIMUM                         \
+            : YY_CAST (YYSIZE_T, -1)))
+
+#define YYSIZEOF(X) YY_CAST (YYPTRDIFF_T, sizeof (X))
+
+
+/* Stored state numbers (used for stacks). */
+typedef yytype_int8 yy_state_t;
+
+/* State numbers in computations.  */
+typedef int yy_state_fast_t;
+
+#ifndef YY_
+# if defined YYENABLE_NLS && YYENABLE_NLS
+#  if ENABLE_NLS
+#   include <libintl.h> /* INFRINGES ON USER NAME SPACE */
+#   define YY_(Msgid) dgettext ("bison-runtime", Msgid)
+#  endif
+# endif
+# ifndef YY_
+#  define YY_(Msgid) Msgid
+# endif
+#endif
+
+
+#ifndef YY_ATTRIBUTE_PURE
+# if defined __GNUC__ && 2 < __GNUC__ + (96 <= __GNUC_MINOR__)
+#  define YY_ATTRIBUTE_PURE __attribute__ ((__pure__))
+# else
+#  define YY_ATTRIBUTE_PURE
+# endif
+#endif
+
+#ifndef YY_ATTRIBUTE_UNUSED
+# if defined __GNUC__ && 2 < __GNUC__ + (7 <= __GNUC_MINOR__)
+#  define YY_ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+# else
+#  define YY_ATTRIBUTE_UNUSED
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E.  */
+#if ! defined lint || defined __GNUC__
+# define YY_USE(E) ((void) (E))
+#else
+# define YY_USE(E) /* empty */
+#endif
+
+/* Suppress an incorrect diagnostic about yylval being uninitialized.  */
+#if defined __GNUC__ && ! defined __ICC && 406 <= __GNUC__ * 100 + __GNUC_MINOR__
+# if __GNUC__ * 100 + __GNUC_MINOR__ < 407
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")
+# else
+#  define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN                           \
+    _Pragma ("GCC diagnostic push")                                     \
+    _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")              \
+    _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# endif
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END      \
+    _Pragma ("GCC diagnostic pop")
+#else
+# define YY_INITIAL_VALUE(Value) Value
+#endif
+#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END
+#endif
+#ifndef YY_INITIAL_VALUE
+# define YY_INITIAL_VALUE(Value) /* Nothing. */
+#endif
+
+#if defined __cplusplus && defined __GNUC__ && ! defined __ICC && 6 <= __GNUC__
+# define YY_IGNORE_USELESS_CAST_BEGIN                          \
+    _Pragma ("GCC diagnostic push")                            \
+    _Pragma ("GCC diagnostic ignored \"-Wuseless-cast\"")
+# define YY_IGNORE_USELESS_CAST_END            \
+    _Pragma ("GCC diagnostic pop")
+#endif
+#ifndef YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_BEGIN
+# define YY_IGNORE_USELESS_CAST_END
+#endif
+
+
+#define YY_ASSERT(E) ((void) (0 && (E)))
+
+#if !defined yyoverflow
+
+/* The parser invokes alloca or malloc; define the necessary symbols.  */
+
+# ifdef YYSTACK_USE_ALLOCA
+#  if YYSTACK_USE_ALLOCA
+#   ifdef __GNUC__
+#    define YYSTACK_ALLOC __builtin_alloca
+#   elif defined __BUILTIN_VA_ARG_INCR
+#    include <alloca.h> /* INFRINGES ON USER NAME SPACE */
+#   elif defined _AIX
+#    define YYSTACK_ALLOC __alloca
+#   elif defined _MSC_VER
+#    include <malloc.h> /* INFRINGES ON USER NAME SPACE */
+#    define alloca _alloca
+#   else
+#    define YYSTACK_ALLOC alloca
+#    if ! defined _ALLOCA_H && ! defined EXIT_SUCCESS
+#     include <stdlib.h> /* INFRINGES ON USER NAME SPACE */
+      /* Use EXIT_SUCCESS as a witness for stdlib.h.  */
+#     ifndef EXIT_SUCCESS
+#      define EXIT_SUCCESS 0
+#     endif
+#    endif
+#   endif
+#  endif
+# endif
+
+# ifdef YYSTACK_ALLOC
+   /* Pacify GCC's 'empty if-body' warning.  */
+#  define YYSTACK_FREE(Ptr) do { /* empty */; } while (0)
+#  ifndef YYSTACK_ALLOC_MAXIMUM
+    /* The OS might guarantee only one guard page at the bottom of the stack,
+       and a page size can be as small as 4096 bytes.  So we cannot safely
+       invoke alloca (N) if N exceeds 4096.  Use a slightly smaller number
+       to allow for a few compiler-allocated temporary stack slots.  */
+#   define YYSTACK_ALLOC_MAXIMUM 4032 /* reasonable circa 2006 */
+#  endif
+# else
+#  define YYSTACK_ALLOC YYMALLOC
+#  define YYSTACK_FREE YYFREE
+#  ifndef YYSTACK_ALLOC_MAXIMUM
+#   define YYSTACK_ALLOC_MAXIMUM YYSIZE_MAXIMUM
+#  endif
+#  if (defined __cplusplus && ! defined EXIT_SUCCESS \
+       && ! ((defined YYMALLOC || defined malloc) \
+             && (defined YYFREE || defined free)))
+#   include <stdlib.h> /* INFRINGES ON USER NAME SPACE */
+#   ifndef EXIT_SUCCESS
+#    define EXIT_SUCCESS 0
+#   endif
+#  endif
+#  ifndef YYMALLOC
+#   define YYMALLOC malloc
+#   if ! defined malloc && ! defined EXIT_SUCCESS
+void *malloc (YYSIZE_T); /* INFRINGES ON USER NAME SPACE */
+#   endif
+#  endif
+#  ifndef YYFREE
+#   define YYFREE free
+#   if ! defined free && ! defined EXIT_SUCCESS
+void free (void *); /* INFRINGES ON USER NAME SPACE */
+#   endif
+#  endif
+# endif
+#endif /* !defined yyoverflow */
+
+#if (! defined yyoverflow \
+     && (! defined __cplusplus \
+         || (defined YYSTYPE_IS_TRIVIAL && YYSTYPE_IS_TRIVIAL)))
+
+/* A type that is properly aligned for any stack member.  */
+union yyalloc
+{
+  yy_state_t yyss_alloc;
+  YYSTYPE yyvs_alloc;
+};
+
+/* The size of the maximum gap between one aligned stack and the next.  */
+# define YYSTACK_GAP_MAXIMUM (YYSIZEOF (union yyalloc) - 1)
+
+/* The size of an array large to enough to hold all stacks, each with
+   N elements.  */
+# define YYSTACK_BYTES(N) \
+     ((N) * (YYSIZEOF (yy_state_t) + YYSIZEOF (YYSTYPE)) \
+      + YYSTACK_GAP_MAXIMUM)
+
+# define YYCOPY_NEEDED 1
+
+/* Relocate STACK from its old location to the new one.  The
+   local variables YYSIZE and YYSTACKSIZE give the old and new number of
+   elements in the stack, and YYPTR gives the new location of the
+   stack.  Advance YYPTR to a properly aligned location for the next
+   stack.  */
+# define YYSTACK_RELOCATE(Stack_alloc, Stack)                           \
+    do                                                                  \
+      {                                                                 \
+        YYPTRDIFF_T yynewbytes;                                         \
+        YYCOPY (&yyptr->Stack_alloc, Stack, yysize);                    \
+        Stack = &yyptr->Stack_alloc;                                    \
+        yynewbytes = yystacksize * YYSIZEOF (*Stack) + YYSTACK_GAP_MAXIMUM; \
+        yyptr += yynewbytes / YYSIZEOF (*yyptr);                        \
+      }                                                                 \
+    while (0)
+
+#endif
+
+#if defined YYCOPY_NEEDED && YYCOPY_NEEDED
+/* Copy COUNT objects from SRC to DST.  The source and destination do
+   not overlap.  */
+# ifndef YYCOPY
+#  if defined __GNUC__ && 1 < __GNUC__
+#   define YYCOPY(Dst, Src, Count) \
+      __builtin_memcpy (Dst, Src, YY_CAST (YYSIZE_T, (Count)) * sizeof (*(Src)))
+#  else
+#   define YYCOPY(Dst, Src, Count)              \
+      do                                        \
+        {                                       \
+          YYPTRDIFF_T yyi;                      \
+          for (yyi = 0; yyi < (Count); yyi++)   \
+            (Dst)[yyi] = (Src)[yyi];            \
+        }                                       \
+      while (0)
+#  endif
+# endif
+#endif /* !YYCOPY_NEEDED */
+
+/* YYFINAL -- State number of the termination state.  */
+#define YYFINAL  2
+/* YYLAST -- Last index in YYTABLE.  */
+#define YYLAST   50
+
+/* YYNTOKENS -- Number of terminals.  */
+#define YYNTOKENS  22
+/* YYNNTS -- Number of nonterminals.  */
+#define YYNNTS  11
+/* YYNRULES -- Number of rules.  */
+#define YYNRULES  51
+/* YYNSTATES -- Number of states.  */
+#define YYNSTATES  61
+
+/* YYMAXUTOK -- Last valid token kind.  */
+#define YYMAXUTOK   273
+
+
+/* YYTRANSLATE(TOKEN-NUM) -- Symbol number corresponding to TOKEN-NUM
+   as returned by yylex, with out-of-bounds checking.  */
+#define YYTRANSLATE(YYX)                                \
+  (0 <= (YYX) && (YYX) <= YYMAXUTOK                     \
+   ? YY_CAST (yysymbol_kind_t, yytranslate[YYX])        \
+   : YYSYMBOL_YYUNDEF)
+
+/* YYTRANSLATE[TOKEN-NUM] -- Symbol number corresponding to TOKEN-NUM
+   as returned by yylex.  */
+static const yytype_int8 yytranslate[] =
+{
+       0,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,    20,     2,     2,    21,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,    19,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,     2,     2,     1,     2,     3,     4,
+       5,     6,     7,     8,     9,    10,    11,    12,    13,    14,
+      15,    16,    17,    18
+};
+
+#if YYDEBUG
+/* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
+static const yytype_int16 yyrline[] =
+{
+       0,   193,   193,   194,   197,   200,   203,   206,   209,   212,
+     215,   221,   227,   236,   242,   254,   257,   261,   266,   270,
+     274,   280,   284,   302,   308,   314,   318,   323,   327,   334,
+     342,   345,   348,   351,   354,   357,   360,   363,   366,   369,
+     372,   375,   378,   381,   384,   387,   390,   393,   396,   401,
+     435,   438
+};
+#endif
+
+/** Accessing symbol of state STATE.  */
+#define YY_ACCESSING_SYMBOL(State) YY_CAST (yysymbol_kind_t, yystos[State])
+
+#if YYDEBUG || 0
+/* The user-facing name of the symbol whose (internal) number is
+   YYSYMBOL.  No bounds checking.  */
+static const char *yysymbol_name (yysymbol_kind_t yysymbol) YY_ATTRIBUTE_UNUSED;
+
+/* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+   First, the terminals, then, starting at YYNTOKENS, nonterminals.  */
+static const char *const yytname[] =
+{
+  "\"end of file\"", "error", "\"invalid token\"", "tAGO", "tDAY",
+  "tDAY_UNIT", "tDAYZONE", "tDST", "tHOUR_UNIT", "tID", "tMERIDIAN",
+  "tMINUTE_UNIT", "tMONTH", "tMONTH_UNIT", "tSEC_UNIT", "tSNUMBER",
+  "tUNUMBER", "tYEAR_UNIT", "tZONE", "':'", "','", "'/'", "$accept",
+  "spec", "item", "time", "zone", "day", "date", "rel", "relunit",
+  "number", "o_merid", YY_NULLPTR
+};
+
+static const char *
+yysymbol_name (yysymbol_kind_t yysymbol)
+{
+  return yytname[yysymbol];
+}
+#endif
+
+#define YYPACT_NINF (-20)
+
+#define yypact_value_is_default(Yyn) \
+  ((Yyn) == YYPACT_NINF)
+
+#define YYTABLE_NINF (-1)
+
+#define yytable_value_is_error(Yyn) \
+  0
+
+/* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
+   STATE-NUM.  */
+static const yytype_int8 yypact[] =
+{
+     -20,     0,   -20,   -19,   -20,   -20,   -20,   -20,   -13,   -20,
+     -20,    30,    15,   -20,    14,   -20,   -20,   -20,   -20,   -20,
+     -20,    19,   -20,   -20,     4,   -20,   -20,   -20,   -20,   -20,
+     -20,   -20,   -20,   -20,   -20,   -20,    -6,   -20,   -20,    16,
+     -20,    17,    23,   -20,   -20,    24,   -20,   -20,   -20,    27,
+      28,   -20,   -20,   -20,    29,   -20,    32,    -8,   -20,   -20,
+     -20
+};
+
+/* YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
+   Performed when YYTABLE does not specify something else to do.  Zero
+   means the default is an error.  */
+static const yytype_int8 yydefact[] =
+{
+       2,     0,     1,    18,    39,    16,    42,    45,     0,    36,
+      48,     0,    49,    33,    15,     3,     4,     5,     7,     6,
+       8,    30,     9,    19,    25,    38,    41,    44,    35,    47,
+      32,    20,    37,    40,    10,    43,    27,    34,    46,     0,
+      31,     0,     0,    17,    29,     0,    24,    28,    23,    50,
+      21,    26,    51,    12,     0,    11,     0,    50,    22,    14,
+      13
+};
+
+/* YYPGOTO[NTERM-NUM].  */
+static const yytype_int8 yypgoto[] =
+{
+     -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,   -20,
+      -7
+};
+
+/* YYDEFGOTO[NTERM-NUM].  */
+static const yytype_int8 yydefgoto[] =
+{
+       0,     1,    15,    16,    17,    18,    19,    20,    21,    22,
+      55
+};
+
+/* YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
+   positive, shift that token.  If negative, reduce the rule whose
+   number is the opposite.  If YYTABLE_NINF, syntax error.  */
+static const yytype_int8 yytable[] =
+{
+       2,    23,    52,    24,     3,     4,     5,    59,     6,    46,
+      47,     7,     8,     9,    10,    11,    12,    13,    14,    31,
+      32,    43,    44,    33,    45,    34,    35,    36,    37,    38,
+      39,    48,    40,    49,    41,    25,    42,    52,    26,    50,
+      51,    27,    53,    28,    29,    57,    54,    30,    58,    56,
+      60
+};
+
+static const yytype_int8 yycheck[] =
+{
+       0,    20,    10,    16,     4,     5,     6,    15,     8,    15,
+      16,    11,    12,    13,    14,    15,    16,    17,    18,     4,
+       5,     7,     3,     8,    20,    10,    11,    12,    13,    14,
+      15,    15,    17,    16,    19,     5,    21,    10,     8,    16,
+      16,    11,    15,    13,    14,    16,    19,    17,    16,    21,
+      57
+};
+
+/* YYSTOS[STATE-NUM] -- The symbol kind of the accessing symbol of
+   state STATE-NUM.  */
+static const yytype_int8 yystos[] =
+{
+       0,    23,     0,     4,     5,     6,     8,    11,    12,    13,
+      14,    15,    16,    17,    18,    24,    25,    26,    27,    28,
+      29,    30,    31,    20,    16,     5,     8,    11,    13,    14,
+      17,     4,     5,     8,    10,    11,    12,    13,    14,    15,
+      17,    19,    21,     7,     3,    20,    15,    16,    15,    16,
+      16,    16,    10,    15,    19,    32,    21,    16,    16,    15,
+      32
+};
+
+/* YYR1[RULE-NUM] -- Symbol kind of the left-hand side of rule RULE-NUM.  */
+static const yytype_int8 yyr1[] =
+{
+       0,    22,    23,    23,    24,    24,    24,    24,    24,    24,
+      25,    25,    25,    25,    25,    26,    26,    26,    27,    27,
+      27,    28,    28,    28,    28,    28,    28,    28,    28,    29,
+      29,    30,    30,    30,    30,    30,    30,    30,    30,    30,
+      30,    30,    30,    30,    30,    30,    30,    30,    30,    31,
+      32,    32
+};
+
+/* YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM.  */
+static const yytype_int8 yyr2[] =
+{
+       0,     2,     0,     2,     1,     1,     1,     1,     1,     1,
+       2,     4,     4,     6,     6,     1,     1,     2,     1,     2,
+       2,     3,     5,     3,     3,     2,     4,     2,     3,     2,
+       1,     2,     2,     1,     2,     2,     1,     2,     2,     1,
+       2,     2,     1,     2,     2,     1,     2,     2,     1,     1,
+       0,     1
+};
+
+
+enum { YYENOMEM = -2 };
+
+#define yyerrok         (yyerrstatus = 0)
+#define yyclearin       (yychar = YYEMPTY)
+
+#define YYACCEPT        goto yyacceptlab
+#define YYABORT         goto yyabortlab
+#define YYERROR         goto yyerrorlab
+#define YYNOMEM         goto yyexhaustedlab
+
+
+#define YYRECOVERING()  (!!yyerrstatus)
+
+#define YYBACKUP(Token, Value)                                    \
+  do                                                              \
+    if (yychar == YYEMPTY)                                        \
+      {                                                           \
+        yychar = (Token);                                         \
+        yylval = (Value);                                         \
+        YYPOPSTACK (yylen);                                       \
+        yystate = *yyssp;                                         \
+        goto yybackup;                                            \
+      }                                                           \
+    else                                                          \
+      {                                                           \
+        yyerror (YY_("syntax error: cannot back up")); \
+        YYERROR;                                                  \
+      }                                                           \
+  while (0)
+
+/* Backward compatibility with an undocumented macro.
+   Use YYerror or YYUNDEF. */
+#define YYERRCODE YYUNDEF
+
+
+/* Enable debugging if requested.  */
+#if YYDEBUG
+
+# ifndef YYFPRINTF
+#  include <stdio.h> /* INFRINGES ON USER NAME SPACE */
+#  define YYFPRINTF fprintf
+# endif
+
+# define YYDPRINTF(Args)                        \
+do {                                            \
+  if (yydebug)                                  \
+    YYFPRINTF Args;                             \
+} while (0)
+
+
+
+
+# define YY_SYMBOL_PRINT(Title, Kind, Value, Location)                    \
+do {                                                                      \
+  if (yydebug)                                                            \
+    {                                                                     \
+      YYFPRINTF (stderr, "%s ", Title);                                   \
+      yy_symbol_print (stderr,                                            \
+                  Kind, Value); \
+      YYFPRINTF (stderr, "\n");                                           \
+    }                                                                     \
+} while (0)
+
+
+/*-----------------------------------.
+| Print this symbol's value on YYO.  |
+`-----------------------------------*/
+
+static void
+yy_symbol_value_print (FILE *yyo,
+                       yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep)
+{
+  FILE *yyoutput = yyo;
+  YY_USE (yyoutput);
+  if (!yyvaluep)
+    return;
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  YY_USE (yykind);
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+}
+
+
+/*---------------------------.
+| Print this symbol on YYO.  |
+`---------------------------*/
+
+static void
+yy_symbol_print (FILE *yyo,
+                 yysymbol_kind_t yykind, YYSTYPE const * const yyvaluep)
+{
+  YYFPRINTF (yyo, "%s %s (",
+             yykind < YYNTOKENS ? "token" : "nterm", yysymbol_name (yykind));
+
+  yy_symbol_value_print (yyo, yykind, yyvaluep);
+  YYFPRINTF (yyo, ")");
+}
+
+/*------------------------------------------------------------------.
+| yy_stack_print -- Print the state stack from its BOTTOM up to its |
+| TOP (included).                                                   |
+`------------------------------------------------------------------*/
+
+static void
+yy_stack_print (yy_state_t *yybottom, yy_state_t *yytop)
+{
+  YYFPRINTF (stderr, "Stack now");
+  for (; yybottom <= yytop; yybottom++)
+    {
+      int yybot = *yybottom;
+      YYFPRINTF (stderr, " %d", yybot);
+    }
+  YYFPRINTF (stderr, "\n");
+}
+
+# define YY_STACK_PRINT(Bottom, Top)                            \
+do {                                                            \
+  if (yydebug)                                                  \
+    yy_stack_print ((Bottom), (Top));                           \
+} while (0)
+
+
+/*------------------------------------------------.
+| Report that the YYRULE is going to be reduced.  |
+`------------------------------------------------*/
+
+static void
+yy_reduce_print (yy_state_t *yyssp, YYSTYPE *yyvsp,
+                 int yyrule)
+{
+  int yylno = yyrline[yyrule];
+  int yynrhs = yyr2[yyrule];
+  int yyi;
+  YYFPRINTF (stderr, "Reducing stack by rule %d (line %d):\n",
+             yyrule - 1, yylno);
+  /* The symbols being reduced.  */
+  for (yyi = 0; yyi < yynrhs; yyi++)
+    {
+      YYFPRINTF (stderr, "   $%d = ", yyi + 1);
+      yy_symbol_print (stderr,
+                       YY_ACCESSING_SYMBOL (+yyssp[yyi + 1 - yynrhs]),
+                       &yyvsp[(yyi + 1) - (yynrhs)]);
+      YYFPRINTF (stderr, "\n");
+    }
+}
+
+# define YY_REDUCE_PRINT(Rule)          \
+do {                                    \
+  if (yydebug)                          \
+    yy_reduce_print (yyssp, yyvsp, Rule); \
+} while (0)
+
+/* Nonzero means print parse trace.  It is left uninitialized so that
+   multiple parsers can coexist.  */
+int yydebug;
+#else /* !YYDEBUG */
+# define YYDPRINTF(Args) ((void) 0)
+# define YY_SYMBOL_PRINT(Title, Kind, Value, Location)
+# define YY_STACK_PRINT(Bottom, Top)
+# define YY_REDUCE_PRINT(Rule)
+#endif /* !YYDEBUG */
+
+
+/* YYINITDEPTH -- initial size of the parser's stacks.  */
+#ifndef YYINITDEPTH
+# define YYINITDEPTH 200
+#endif
+
+/* YYMAXDEPTH -- maximum size the stacks can grow to (effective only
+   if the built-in stack extension method is used).
+
+   Do not make this value too large; the results are undefined if
+   YYSTACK_ALLOC_MAXIMUM < YYSTACK_BYTES (YYMAXDEPTH)
+   evaluated with infinite-precision integer arithmetic.  */
+
+#ifndef YYMAXDEPTH
+# define YYMAXDEPTH 10000
+#endif
+
+
+
+
+
+
+/*-----------------------------------------------.
+| Release the memory associated to this symbol.  |
+`-----------------------------------------------*/
+
+static void
+yydestruct (const char *yymsg,
+            yysymbol_kind_t yykind, YYSTYPE *yyvaluep)
+{
+  YY_USE (yyvaluep);
+  if (!yymsg)
+    yymsg = "Deleting";
+  YY_SYMBOL_PRINT (yymsg, yykind, yyvaluep, yylocationp);
+
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  YY_USE (yykind);
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+}
+
+
+/* Lookahead token kind.  */
+int yychar;
+
+/* The semantic value of the lookahead symbol.  */
+YYSTYPE yylval;
+/* Number of syntax errors so far.  */
+int yynerrs;
+
+
+
+
+/*----------.
+| yyparse.  |
+`----------*/
+
+int
+yyparse (void)
+{
+    yy_state_fast_t yystate = 0;
+    /* Number of tokens to shift before error messages enabled.  */
+    int yyerrstatus = 0;
+
+    /* Refer to the stacks through separate pointers, to allow yyoverflow
+       to reallocate them elsewhere.  */
+
+    /* Their size.  */
+    YYPTRDIFF_T yystacksize = YYINITDEPTH;
+
+    /* The state stack: array, bottom, top.  */
+    yy_state_t yyssa[YYINITDEPTH];
+    yy_state_t *yyss = yyssa;
+    yy_state_t *yyssp = yyss;
+
+    /* The semantic value stack: array, bottom, top.  */
+    YYSTYPE yyvsa[YYINITDEPTH];
+    YYSTYPE *yyvs = yyvsa;
+    YYSTYPE *yyvsp = yyvs;
+
+  int yyn;
+  /* The return value of yyparse.  */
+  int yyresult;
+  /* Lookahead symbol kind.  */
+  yysymbol_kind_t yytoken = YYSYMBOL_YYEMPTY;
+  /* The variables used to return semantic value and location from the
+     action routines.  */
+  YYSTYPE yyval;
+
+
+
+#define YYPOPSTACK(N)   (yyvsp -= (N), yyssp -= (N))
+
+  /* The number of symbols on the RHS of the reduced rule.
+     Keep to zero when no symbol should be popped.  */
+  int yylen = 0;
+
+  YYDPRINTF ((stderr, "Starting parse\n"));
+
+  yychar = YYEMPTY; /* Cause a token to be read.  */
+
+  goto yysetstate;
+
+
+/*------------------------------------------------------------.
+| yynewstate -- push a new state, which is found in yystate.  |
+`------------------------------------------------------------*/
+yynewstate:
+  /* In all cases, when you get here, the value and location stacks
+     have just been pushed.  So pushing a state here evens the stacks.  */
+  yyssp++;
+
+
+/*--------------------------------------------------------------------.
+| yysetstate -- set current state (the top of the stack) to yystate.  |
+`--------------------------------------------------------------------*/
+yysetstate:
+  YYDPRINTF ((stderr, "Entering state %d\n", yystate));
+  YY_ASSERT (0 <= yystate && yystate < YYNSTATES);
+  YY_IGNORE_USELESS_CAST_BEGIN
+  *yyssp = YY_CAST (yy_state_t, yystate);
+  YY_IGNORE_USELESS_CAST_END
+  YY_STACK_PRINT (yyss, yyssp);
+
+  if (yyss + yystacksize - 1 <= yyssp)
+#if !defined yyoverflow && !defined YYSTACK_RELOCATE
+    YYNOMEM;
+#else
+    {
+      /* Get the current used size of the three stacks, in elements.  */
+      YYPTRDIFF_T yysize = yyssp - yyss + 1;
+
+# if defined yyoverflow
+      {
+        /* Give user a chance to reallocate the stack.  Use copies of
+           these so that the &'s don't force the real ones into
+           memory.  */
+        yy_state_t *yyss1 = yyss;
+        YYSTYPE *yyvs1 = yyvs;
+
+        /* Each stack pointer address is followed by the size of the
+           data in use in that stack, in bytes.  This used to be a
+           conditional around just the two extra args, but that might
+           be undefined if yyoverflow is a macro.  */
+        yyoverflow (YY_("memory exhausted"),
+                    &yyss1, yysize * YYSIZEOF (*yyssp),
+                    &yyvs1, yysize * YYSIZEOF (*yyvsp),
+                    &yystacksize);
+        yyss = yyss1;
+        yyvs = yyvs1;
+      }
+# else /* defined YYSTACK_RELOCATE */
+      /* Extend the stack our own way.  */
+      if (YYMAXDEPTH <= yystacksize)
+        YYNOMEM;
+      yystacksize *= 2;
+      if (YYMAXDEPTH < yystacksize)
+        yystacksize = YYMAXDEPTH;
+
+      {
+        yy_state_t *yyss1 = yyss;
+        union yyalloc *yyptr =
+          YY_CAST (union yyalloc *,
+                   YYSTACK_ALLOC (YY_CAST (YYSIZE_T, YYSTACK_BYTES (yystacksize))));
+        if (! yyptr)
+          YYNOMEM;
+        YYSTACK_RELOCATE (yyss_alloc, yyss);
+        YYSTACK_RELOCATE (yyvs_alloc, yyvs);
+#  undef YYSTACK_RELOCATE
+        if (yyss1 != yyssa)
+          YYSTACK_FREE (yyss1);
+      }
+# endif
+
+      yyssp = yyss + yysize - 1;
+      yyvsp = yyvs + yysize - 1;
+
+      YY_IGNORE_USELESS_CAST_BEGIN
+      YYDPRINTF ((stderr, "Stack size increased to %ld\n",
+                  YY_CAST (long, yystacksize)));
+      YY_IGNORE_USELESS_CAST_END
+
+      if (yyss + yystacksize - 1 <= yyssp)
+        YYABORT;
+    }
+#endif /* !defined yyoverflow && !defined YYSTACK_RELOCATE */
+
+
+  if (yystate == YYFINAL)
+    YYACCEPT;
+
+  goto yybackup;
+
+
+/*-----------.
+| yybackup.  |
+`-----------*/
+yybackup:
+  /* Do appropriate processing given the current state.  Read a
+     lookahead token if we need one and don't already have one.  */
+
+  /* First try to decide what to do without reference to lookahead token.  */
+  yyn = yypact[yystate];
+  if (yypact_value_is_default (yyn))
+    goto yydefault;
+
+  /* Not known => get a lookahead token if don't already have one.  */
+
+  /* YYCHAR is either empty, or end-of-input, or a valid lookahead.  */
+  if (yychar == YYEMPTY)
+    {
+      YYDPRINTF ((stderr, "Reading a token\n"));
+      yychar = yylex ();
+    }
+
+  if (yychar <= YYEOF)
+    {
+      yychar = YYEOF;
+      yytoken = YYSYMBOL_YYEOF;
+      YYDPRINTF ((stderr, "Now at end of input.\n"));
+    }
+  else if (yychar == YYerror)
+    {
+      /* The scanner already issued an error message, process directly
+         to error recovery.  But do not keep the error token as
+         lookahead, it is too special and may lead us to an endless
+         loop in error recovery. */
+      yychar = YYUNDEF;
+      yytoken = YYSYMBOL_YYerror;
+      goto yyerrlab1;
+    }
+  else
+    {
+      yytoken = YYTRANSLATE (yychar);
+      YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
+    }
+
+  /* If the proper action on seeing token YYTOKEN is to reduce or to
+     detect an error, take that action.  */
+  yyn += yytoken;
+  if (yyn < 0 || YYLAST < yyn || yycheck[yyn] != yytoken)
+    goto yydefault;
+  yyn = yytable[yyn];
+  if (yyn <= 0)
+    {
+      if (yytable_value_is_error (yyn))
+        goto yyerrlab;
+      yyn = -yyn;
+      goto yyreduce;
+    }
+
+  /* Count tokens shifted since error; after three, turn off error
+     status.  */
+  if (yyerrstatus)
+    yyerrstatus--;
+
+  /* Shift the lookahead token.  */
+  YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
+  yystate = yyn;
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  *++yyvsp = yylval;
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+
+  /* Discard the shifted token.  */
+  yychar = YYEMPTY;
+  goto yynewstate;
+
+
+/*-----------------------------------------------------------.
+| yydefault -- do the default action for the current state.  |
+`-----------------------------------------------------------*/
+yydefault:
+  yyn = yydefact[yystate];
+  if (yyn == 0)
+    goto yyerrlab;
+  goto yyreduce;
+
+
+/*-----------------------------.
+| yyreduce -- do a reduction.  |
+`-----------------------------*/
+yyreduce:
+  /* yyn is the number of a rule to reduce with.  */
+  yylen = yyr2[yyn];
+
+  /* If YYLEN is nonzero, implement the default value of the action:
+     '$$ = $1'.
+
+     Otherwise, the following line sets YYVAL to garbage.
+     This behavior is undocumented and Bison
+     users should not rely upon it.  Assigning to YYVAL
+     unconditionally makes the parser a bit smaller, and it avoids a
+     GCC warning that YYVAL may be used uninitialized.  */
+  yyval = yyvsp[1-yylen];
+
+
+  YY_REDUCE_PRINT (yyn);
+  switch (yyn)
+    {
+  case 4: /* item: time  */
+#line 197 "getdate.y"
+               {
+	    yyHaveTime++;
+	}
+#line 1364 "getdate.c"
+    break;
+
+  case 5: /* item: zone  */
+#line 200 "getdate.y"
+               {
+	    yyHaveZone++;
+	}
+#line 1372 "getdate.c"
+    break;
+
+  case 6: /* item: date  */
+#line 203 "getdate.y"
+               {
+	    yyHaveDate++;
+	}
+#line 1380 "getdate.c"
+    break;
+
+  case 7: /* item: day  */
+#line 206 "getdate.y"
+              {
+	    yyHaveDay++;
+	}
+#line 1388 "getdate.c"
+    break;
+
+  case 8: /* item: rel  */
+#line 209 "getdate.y"
+              {
+	    yyHaveRel++;
+	}
+#line 1396 "getdate.c"
+    break;
+
+  case 10: /* time: tUNUMBER tMERIDIAN  */
+#line 215 "getdate.y"
+                             {
+	    yyHour = (yyvsp[-1].Number);
+	    yyMinutes = 0;
+	    yySeconds = 0;
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1407 "getdate.c"
+    break;
+
+  case 11: /* time: tUNUMBER ':' tUNUMBER o_merid  */
+#line 221 "getdate.y"
+                                        {
+	    yyHour = (yyvsp[-3].Number);
+	    yyMinutes = (yyvsp[-1].Number);
+	    yySeconds = 0;
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1418 "getdate.c"
+    break;
+
+  case 12: /* time: tUNUMBER ':' tUNUMBER tSNUMBER  */
+#line 227 "getdate.y"
+                                         {
+	    yyHour = (yyvsp[-3].Number);
+	    yyMinutes = (yyvsp[-1].Number);
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ((yyvsp[0].Number) < 0
+			  ? -(yyvsp[0].Number) % 100 + (-(yyvsp[0].Number) / 100) * 60
+			  : - ((yyvsp[0].Number) % 100 + ((yyvsp[0].Number) / 100) * 60));
+	}
+#line 1432 "getdate.c"
+    break;
+
+  case 13: /* time: tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid  */
+#line 236 "getdate.y"
+                                                     {
+	    yyHour = (yyvsp[-5].Number);
+	    yyMinutes = (yyvsp[-3].Number);
+	    yySeconds = (yyvsp[-1].Number);
+	    yyMeridian = (yyvsp[0].Meridian);
+	}
+#line 1443 "getdate.c"
+    break;
+
+  case 14: /* time: tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER  */
+#line 242 "getdate.y"
+                                                      {
+	    yyHour = (yyvsp[-5].Number);
+	    yyMinutes = (yyvsp[-3].Number);
+	    yySeconds = (yyvsp[-1].Number);
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ((yyvsp[0].Number) < 0
+			  ? -(yyvsp[0].Number) % 100 + (-(yyvsp[0].Number) / 100) * 60
+			  : - ((yyvsp[0].Number) % 100 + ((yyvsp[0].Number) / 100) * 60));
+	}
+#line 1458 "getdate.c"
+    break;
+
+  case 15: /* zone: tZONE  */
+#line 254 "getdate.y"
+                {
+	    yyTimezone = (yyvsp[0].Number);
+	}
+#line 1466 "getdate.c"
+    break;
+
+  case 16: /* zone: tDAYZONE  */
+#line 257 "getdate.y"
+                   {
+	    yyTimezone = (yyvsp[0].Number) - 60;
+	}
+#line 1474 "getdate.c"
+    break;
+
+  case 17: /* zone: tZONE tDST  */
+#line 261 "getdate.y"
+                     {
+	    yyTimezone = (yyvsp[-1].Number) - 60;
+	}
+#line 1482 "getdate.c"
+    break;
+
+  case 18: /* day: tDAY  */
+#line 266 "getdate.y"
+               {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = (yyvsp[0].Number);
+	}
+#line 1491 "getdate.c"
+    break;
+
+  case 19: /* day: tDAY ','  */
+#line 270 "getdate.y"
+                   {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = (yyvsp[-1].Number);
+	}
+#line 1500 "getdate.c"
+    break;
+
+  case 20: /* day: tUNUMBER tDAY  */
+#line 274 "getdate.y"
+                        {
+	    yyDayOrdinal = (yyvsp[-1].Number);
+	    yyDayNumber = (yyvsp[0].Number);
+	}
+#line 1509 "getdate.c"
+    break;
+
+  case 21: /* date: tUNUMBER '/' tUNUMBER  */
+#line 280 "getdate.y"
+                                {
+	    yyMonth = (yyvsp[-2].Number);
+	    yyDay = (yyvsp[0].Number);
+	}
+#line 1518 "getdate.c"
+    break;
+
+  case 22: /* date: tUNUMBER '/' tUNUMBER '/' tUNUMBER  */
+#line 284 "getdate.y"
+                                             {
+	  /* Interpret as YYYY/MM/DD if $1 >= 1000, otherwise as MM/DD/YY.
+	     The goal in recognizing YYYY/MM/DD is solely to support legacy
+	     machine-generated dates like those in an RCS log listing.  If
+	     you want portability, use the ISO 8601 format.  */
+	  if ((yyvsp[-4].Number) >= 1000)
+	    {
+	      yyYear = (yyvsp[-4].Number);
+	      yyMonth = (yyvsp[-2].Number);
+	      yyDay = (yyvsp[0].Number);
+	    }
+	  else
+	    {
+	      yyMonth = (yyvsp[-4].Number);
+	      yyDay = (yyvsp[-2].Number);
+	      yyYear = (yyvsp[0].Number);
+	    }
+	}
+#line 1541 "getdate.c"
+    break;
+
+  case 23: /* date: tUNUMBER tSNUMBER tSNUMBER  */
+#line 302 "getdate.y"
+                                     {
+	    /* ISO 8601 format.  yyyy-mm-dd.  */
+	    yyYear = (yyvsp[-2].Number);
+	    yyMonth = -(yyvsp[-1].Number);
+	    yyDay = -(yyvsp[0].Number);
+	}
+#line 1552 "getdate.c"
+    break;
+
+  case 24: /* date: tUNUMBER tMONTH tSNUMBER  */
+#line 308 "getdate.y"
+                                   {
+	    /* e.g. 17-JUN-1992.  */
+	    yyDay = (yyvsp[-2].Number);
+	    yyMonth = (yyvsp[-1].Number);
+	    yyYear = -(yyvsp[0].Number);
+	}
+#line 1563 "getdate.c"
+    break;
+
+  case 25: /* date: tMONTH tUNUMBER  */
+#line 314 "getdate.y"
+                          {
+	    yyMonth = (yyvsp[-1].Number);
+	    yyDay = (yyvsp[0].Number);
+	}
+#line 1572 "getdate.c"
+    break;
+
+  case 26: /* date: tMONTH tUNUMBER ',' tUNUMBER  */
+#line 318 "getdate.y"
+                                       {
+	    yyMonth = (yyvsp[-3].Number);
+	    yyDay = (yyvsp[-2].Number);
+	    yyYear = (yyvsp[0].Number);
+	}
+#line 1582 "getdate.c"
+    break;
+
+  case 27: /* date: tUNUMBER tMONTH  */
+#line 323 "getdate.y"
+                          {
+	    yyMonth = (yyvsp[0].Number);
+	    yyDay = (yyvsp[-1].Number);
+	}
+#line 1591 "getdate.c"
+    break;
+
+  case 28: /* date: tUNUMBER tMONTH tUNUMBER  */
+#line 327 "getdate.y"
+                                   {
+	    yyMonth = (yyvsp[-1].Number);
+	    yyDay = (yyvsp[-2].Number);
+	    yyYear = (yyvsp[0].Number);
+	}
+#line 1601 "getdate.c"
+    break;
+
+  case 29: /* rel: relunit tAGO  */
+#line 334 "getdate.y"
+                       {
+	    yyRelSeconds = -yyRelSeconds;
+	    yyRelMinutes = -yyRelMinutes;
+	    yyRelHour = -yyRelHour;
+	    yyRelDay = -yyRelDay;
+	    yyRelMonth = -yyRelMonth;
+	    yyRelYear = -yyRelYear;
+	}
+#line 1614 "getdate.c"
+    break;
+
+  case 31: /* relunit: tUNUMBER tYEAR_UNIT  */
+#line 345 "getdate.y"
+                              {
+	    yyRelYear += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1622 "getdate.c"
+    break;
+
+  case 32: /* relunit: tSNUMBER tYEAR_UNIT  */
+#line 348 "getdate.y"
+                              {
+	    yyRelYear += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1630 "getdate.c"
+    break;
+
+  case 33: /* relunit: tYEAR_UNIT  */
+#line 351 "getdate.y"
+                     {
+	    yyRelYear += (yyvsp[0].Number);
+	}
+#line 1638 "getdate.c"
+    break;
+
+  case 34: /* relunit: tUNUMBER tMONTH_UNIT  */
+#line 354 "getdate.y"
+                               {
+	    yyRelMonth += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1646 "getdate.c"
+    break;
+
+  case 35: /* relunit: tSNUMBER tMONTH_UNIT  */
+#line 357 "getdate.y"
+                               {
+	    yyRelMonth += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1654 "getdate.c"
+    break;
+
+  case 36: /* relunit: tMONTH_UNIT  */
+#line 360 "getdate.y"
+                      {
+	    yyRelMonth += (yyvsp[0].Number);
+	}
+#line 1662 "getdate.c"
+    break;
+
+  case 37: /* relunit: tUNUMBER tDAY_UNIT  */
+#line 363 "getdate.y"
+                             {
+	    yyRelDay += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1670 "getdate.c"
+    break;
+
+  case 38: /* relunit: tSNUMBER tDAY_UNIT  */
+#line 366 "getdate.y"
+                             {
+	    yyRelDay += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1678 "getdate.c"
+    break;
+
+  case 39: /* relunit: tDAY_UNIT  */
+#line 369 "getdate.y"
+                    {
+	    yyRelDay += (yyvsp[0].Number);
+	}
+#line 1686 "getdate.c"
+    break;
+
+  case 40: /* relunit: tUNUMBER tHOUR_UNIT  */
+#line 372 "getdate.y"
+                              {
+	    yyRelHour += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1694 "getdate.c"
+    break;
+
+  case 41: /* relunit: tSNUMBER tHOUR_UNIT  */
+#line 375 "getdate.y"
+                              {
+	    yyRelHour += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1702 "getdate.c"
+    break;
+
+  case 42: /* relunit: tHOUR_UNIT  */
+#line 378 "getdate.y"
+                     {
+	    yyRelHour += (yyvsp[0].Number);
+	}
+#line 1710 "getdate.c"
+    break;
+
+  case 43: /* relunit: tUNUMBER tMINUTE_UNIT  */
+#line 381 "getdate.y"
+                                {
+	    yyRelMinutes += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1718 "getdate.c"
+    break;
+
+  case 44: /* relunit: tSNUMBER tMINUTE_UNIT  */
+#line 384 "getdate.y"
+                                {
+	    yyRelMinutes += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1726 "getdate.c"
+    break;
+
+  case 45: /* relunit: tMINUTE_UNIT  */
+#line 387 "getdate.y"
+                       {
+	    yyRelMinutes += (yyvsp[0].Number);
+	}
+#line 1734 "getdate.c"
+    break;
+
+  case 46: /* relunit: tUNUMBER tSEC_UNIT  */
+#line 390 "getdate.y"
+                             {
+	    yyRelSeconds += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1742 "getdate.c"
+    break;
+
+  case 47: /* relunit: tSNUMBER tSEC_UNIT  */
+#line 393 "getdate.y"
+                             {
+	    yyRelSeconds += (yyvsp[-1].Number) * (yyvsp[0].Number);
+	}
+#line 1750 "getdate.c"
+    break;
+
+  case 48: /* relunit: tSEC_UNIT  */
+#line 396 "getdate.y"
+                    {
+	    yyRelSeconds += (yyvsp[0].Number);
+	}
+#line 1758 "getdate.c"
+    break;
+
+  case 49: /* number: tUNUMBER  */
+#line 402 "getdate.y"
+          {
+	    if (yyHaveTime && yyHaveDate && !yyHaveRel)
+	      yyYear = (yyvsp[0].Number);
+	    else
+	      {
+		if ((yyvsp[0].Number)>10000)
+		  {
+		    yyHaveDate++;
+		    yyDay= ((yyvsp[0].Number))%100;
+		    yyMonth= ((yyvsp[0].Number)/100)%100;
+		    yyYear = (yyvsp[0].Number)/10000;
+		  }
+		else
+		  {
+		    yyHaveTime++;
+		    if ((yyvsp[0].Number) < 100)
+		      {
+			yyHour = (yyvsp[0].Number);
+			yyMinutes = 0;
+		      }
+		    else
+		      {
+		    	yyHour = (yyvsp[0].Number) / 100;
+		    	yyMinutes = (yyvsp[0].Number) % 100;
+		      }
+		    yySeconds = 0;
+		    yyMeridian = MER24;
+		  }
+	      }
+	  }
+#line 1793 "getdate.c"
+    break;
+
+  case 50: /* o_merid: %empty  */
+#line 435 "getdate.y"
+          {
+	    (yyval.Meridian) = MER24;
+	  }
+#line 1801 "getdate.c"
+    break;
+
+  case 51: /* o_merid: tMERIDIAN  */
+#line 439 "getdate.y"
+          {
+	    (yyval.Meridian) = (yyvsp[0].Meridian);
+	  }
+#line 1809 "getdate.c"
+    break;
+
+
+#line 1813 "getdate.c"
+
+      default: break;
+    }
+  /* User semantic actions sometimes alter yychar, and that requires
+     that yytoken be updated with the new translation.  We take the
+     approach of translating immediately before every use of yytoken.
+     One alternative is translating here after every semantic action,
+     but that translation would be missed if the semantic action invokes
+     YYABORT, YYACCEPT, or YYERROR immediately after altering yychar or
+     if it invokes YYBACKUP.  In the case of YYABORT or YYACCEPT, an
+     incorrect destructor might then be invoked immediately.  In the
+     case of YYERROR or YYBACKUP, subsequent parser actions might lead
+     to an incorrect destructor call or verbose syntax error message
+     before the lookahead is translated.  */
+  YY_SYMBOL_PRINT ("-> $$ =", YY_CAST (yysymbol_kind_t, yyr1[yyn]), &yyval, &yyloc);
+
+  YYPOPSTACK (yylen);
+  yylen = 0;
+
+  *++yyvsp = yyval;
+
+  /* Now 'shift' the result of the reduction.  Determine what state
+     that goes to, based on the state we popped back to and the rule
+     number reduced by.  */
+  {
+    const int yylhs = yyr1[yyn] - YYNTOKENS;
+    const int yyi = yypgoto[yylhs] + *yyssp;
+    yystate = (0 <= yyi && yyi <= YYLAST && yycheck[yyi] == *yyssp
+               ? yytable[yyi]
+               : yydefgoto[yylhs]);
+  }
+
+  goto yynewstate;
+
+
+/*--------------------------------------.
+| yyerrlab -- here on detecting error.  |
+`--------------------------------------*/
+yyerrlab:
+  /* Make sure we have latest lookahead translation.  See comments at
+     user semantic actions for why this is necessary.  */
+  yytoken = yychar == YYEMPTY ? YYSYMBOL_YYEMPTY : YYTRANSLATE (yychar);
+  /* If not already recovering from an error, report this error.  */
+  if (!yyerrstatus)
+    {
+      ++yynerrs;
+      yyerror (YY_("syntax error"));
+    }
+
+  if (yyerrstatus == 3)
+    {
+      /* If just tried and failed to reuse lookahead token after an
+         error, discard it.  */
+
+      if (yychar <= YYEOF)
+        {
+          /* Return failure if at end of input.  */
+          if (yychar == YYEOF)
+            YYABORT;
+        }
+      else
+        {
+          yydestruct ("Error: discarding",
+                      yytoken, &yylval);
+          yychar = YYEMPTY;
+        }
+    }
+
+  /* Else will try to reuse lookahead token after shifting the error
+     token.  */
+  goto yyerrlab1;
+
+
+/*---------------------------------------------------.
+| yyerrorlab -- error raised explicitly by YYERROR.  |
+`---------------------------------------------------*/
+yyerrorlab:
+  /* Pacify compilers when the user code never invokes YYERROR and the
+     label yyerrorlab therefore never appears in user code.  */
+  if (0)
+    YYERROR;
+  ++yynerrs;
+
+  /* Do not reclaim the symbols of the rule whose action triggered
+     this YYERROR.  */
+  YYPOPSTACK (yylen);
+  yylen = 0;
+  YY_STACK_PRINT (yyss, yyssp);
+  yystate = *yyssp;
+  goto yyerrlab1;
+
+
+/*-------------------------------------------------------------.
+| yyerrlab1 -- common code for both syntax error and YYERROR.  |
+`-------------------------------------------------------------*/
+yyerrlab1:
+  yyerrstatus = 3;      /* Each real token shifted decrements this.  */
+
+  /* Pop stack until we find a state that shifts the error token.  */
+  for (;;)
+    {
+      yyn = yypact[yystate];
+      if (!yypact_value_is_default (yyn))
+        {
+          yyn += YYSYMBOL_YYerror;
+          if (0 <= yyn && yyn <= YYLAST && yycheck[yyn] == YYSYMBOL_YYerror)
+            {
+              yyn = yytable[yyn];
+              if (0 < yyn)
+                break;
+            }
+        }
+
+      /* Pop the current state because it cannot handle the error token.  */
+      if (yyssp == yyss)
+        YYABORT;
+
+
+      yydestruct ("Error: popping",
+                  YY_ACCESSING_SYMBOL (yystate), yyvsp);
+      YYPOPSTACK (1);
+      yystate = *yyssp;
+      YY_STACK_PRINT (yyss, yyssp);
+    }
+
+  YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+  *++yyvsp = yylval;
+  YY_IGNORE_MAYBE_UNINITIALIZED_END
+
+
+  /* Shift the error token.  */
+  YY_SYMBOL_PRINT ("Shifting", YY_ACCESSING_SYMBOL (yyn), yyvsp, yylsp);
+
+  yystate = yyn;
+  goto yynewstate;
+
+
+/*-------------------------------------.
+| yyacceptlab -- YYACCEPT comes here.  |
+`-------------------------------------*/
+yyacceptlab:
+  yyresult = 0;
+  goto yyreturnlab;
+
+
+/*-----------------------------------.
+| yyabortlab -- YYABORT comes here.  |
+`-----------------------------------*/
+yyabortlab:
+  yyresult = 1;
+  goto yyreturnlab;
+
+
+/*-----------------------------------------------------------.
+| yyexhaustedlab -- YYNOMEM (memory exhaustion) comes here.  |
+`-----------------------------------------------------------*/
+yyexhaustedlab:
+  yyerror (YY_("memory exhausted"));
+  yyresult = 2;
+  goto yyreturnlab;
+
+
+/*----------------------------------------------------------.
+| yyreturnlab -- parsing is finished, clean up and return.  |
+`----------------------------------------------------------*/
+yyreturnlab:
+  if (yychar != YYEMPTY)
+    {
+      /* Make sure we have latest lookahead translation.  See comments at
+         user semantic actions for why this is necessary.  */
+      yytoken = YYTRANSLATE (yychar);
+      yydestruct ("Cleanup: discarding lookahead",
+                  yytoken, &yylval);
+    }
+  /* Do not reclaim the symbols of the rule whose action triggered
+     this YYABORT or YYACCEPT.  */
+  YYPOPSTACK (yylen);
+  YY_STACK_PRINT (yyss, yyssp);
+  while (yyssp != yyss)
+    {
+      yydestruct ("Cleanup: popping",
+                  YY_ACCESSING_SYMBOL (+*yyssp), yyvsp);
+      YYPOPSTACK (1);
+    }
+#ifndef yyoverflow
+  if (yyss != yyssa)
+    YYSTACK_FREE (yyss);
+#endif
+
+  return yyresult;
+}
+
+#line 444 "getdate.y"
+
+
+/* Include this file down here because bison inserts code above which
+   may define-away `const'.  We want the prototype for get_date to have
+   the same signature as the function definition does. */
+#include "getdate.h"
+
+extern struct tm	*gmtime (const time_t *timep);
+extern struct tm	*localtime (const time_t *timep);
+extern time_t		mktime (struct tm *tm);
+
+/* Month and day table. */
+static TABLE const MonthDayTable[] = {
+    { "january",	tMONTH,  1 },
+    { "february",	tMONTH,  2 },
+    { "march",		tMONTH,  3 },
+    { "april",		tMONTH,  4 },
+    { "may",		tMONTH,  5 },
+    { "june",		tMONTH,  6 },
+    { "july",		tMONTH,  7 },
+    { "august",		tMONTH,  8 },
+    { "september",	tMONTH,  9 },
+    { "sept",		tMONTH,  9 },
+    { "october",	tMONTH, 10 },
+    { "november",	tMONTH, 11 },
+    { "december",	tMONTH, 12 },
+    { "sunday",		tDAY, 0 },
+    { "monday",		tDAY, 1 },
+    { "tuesday",	tDAY, 2 },
+    { "tues",		tDAY, 2 },
+    { "wednesday",	tDAY, 3 },
+    { "wednes",		tDAY, 3 },
+    { "thursday",	tDAY, 4 },
+    { "thur",		tDAY, 4 },
+    { "thurs",		tDAY, 4 },
+    { "friday",		tDAY, 5 },
+    { "saturday",	tDAY, 6 },
+    { NULL, 0, 0 }
+};
+
+/* Time units table. */
+static TABLE const UnitsTable[] = {
+    { "year",		tYEAR_UNIT,	1 },
+    { "month",		tMONTH_UNIT,	1 },
+    { "fortnight",	tDAY_UNIT,	14 },
+    { "week",		tDAY_UNIT,	7 },
+    { "day",		tDAY_UNIT,	1 },
+    { "hour",		tHOUR_UNIT,	1 },
+    { "minute",		tMINUTE_UNIT,	1 },
+    { "min",		tMINUTE_UNIT,	1 },
+    { "second",		tSEC_UNIT,	1 },
+    { "sec",		tSEC_UNIT,	1 },
+    { NULL, 0, 0 }
+};
+
+/* Assorted relative-time words. */
+static TABLE const OtherTable[] = {
+    { "tomorrow",	tMINUTE_UNIT,	1 * 24 * 60 },
+    { "yesterday",	tMINUTE_UNIT,	-1 * 24 * 60 },
+    { "today",		tMINUTE_UNIT,	0 },
+    { "now",		tMINUTE_UNIT,	0 },
+    { "last",		tUNUMBER,	-1 },
+    { "this",		tMINUTE_UNIT,	0 },
+    { "next",		tUNUMBER,	1 },
+    { "first",		tUNUMBER,	1 },
+/*  { "second",		tUNUMBER,	2 }, */
+    { "third",		tUNUMBER,	3 },
+    { "fourth",		tUNUMBER,	4 },
+    { "fifth",		tUNUMBER,	5 },
+    { "sixth",		tUNUMBER,	6 },
+    { "seventh",	tUNUMBER,	7 },
+    { "eighth",		tUNUMBER,	8 },
+    { "ninth",		tUNUMBER,	9 },
+    { "tenth",		tUNUMBER,	10 },
+    { "eleventh",	tUNUMBER,	11 },
+    { "twelfth",	tUNUMBER,	12 },
+    { "ago",		tAGO,	1 },
+    { NULL, 0, 0 }
+};
+
+/* The timezone table. */
+static TABLE const TimezoneTable[] = {
+    { "gmt",	tZONE,     HOUR ( 0) },	/* Greenwich Mean */
+    { "ut",	tZONE,     HOUR ( 0) },	/* Universal (Coordinated) */
+    { "utc",	tZONE,     HOUR ( 0) },
+    { "wet",	tZONE,     HOUR ( 0) },	/* Western European */
+    { "bst",	tDAYZONE,  HOUR ( 0) },	/* British Summer */
+    { "wat",	tZONE,     HOUR ( 1) },	/* West Africa */
+    { "at",	tZONE,     HOUR ( 2) },	/* Azores */
+#if	0
+    /* For completeness.  BST is also British Summer, and GST is
+     * also Guam Standard. */
+    { "bst",	tZONE,     HOUR ( 3) },	/* Brazil Standard */
+    { "gst",	tZONE,     HOUR ( 3) },	/* Greenland Standard */
+#endif
+#if 0
+    { "nft",	tZONE,     HOUR (3.5) },	/* Newfoundland */
+    { "nst",	tZONE,     HOUR (3.5) },	/* Newfoundland Standard */
+    { "ndt",	tDAYZONE,  HOUR (3.5) },	/* Newfoundland Daylight */
+#endif
+    { "ast",	tZONE,     HOUR ( 4) },	/* Atlantic Standard */
+    { "adt",	tDAYZONE,  HOUR ( 4) },	/* Atlantic Daylight */
+    { "est",	tZONE,     HOUR ( 5) },	/* Eastern Standard */
+    { "edt",	tDAYZONE,  HOUR ( 5) },	/* Eastern Daylight */
+    { "cst",	tZONE,     HOUR ( 6) },	/* Central Standard */
+    { "cdt",	tDAYZONE,  HOUR ( 6) },	/* Central Daylight */
+    { "mst",	tZONE,     HOUR ( 7) },	/* Mountain Standard */
+    { "mdt",	tDAYZONE,  HOUR ( 7) },	/* Mountain Daylight */
+    { "pst",	tZONE,     HOUR ( 8) },	/* Pacific Standard */
+    { "pdt",	tDAYZONE,  HOUR ( 8) },	/* Pacific Daylight */
+    { "yst",	tZONE,     HOUR ( 9) },	/* Yukon Standard */
+    { "ydt",	tDAYZONE,  HOUR ( 9) },	/* Yukon Daylight */
+    { "hst",	tZONE,     HOUR (10) },	/* Hawaii Standard */
+    { "hdt",	tDAYZONE,  HOUR (10) },	/* Hawaii Daylight */
+    { "cat",	tZONE,     HOUR (10) },	/* Central Alaska */
+    { "ahst",	tZONE,     HOUR (10) },	/* Alaska-Hawaii Standard */
+    { "nt",	tZONE,     HOUR (11) },	/* Nome */
+    { "idlw",	tZONE,     HOUR (12) },	/* International Date Line West */
+    { "cet",	tZONE,     -HOUR (1) },	/* Central European */
+    { "met",	tZONE,     -HOUR (1) },	/* Middle European */
+    { "mewt",	tZONE,     -HOUR (1) },	/* Middle European Winter */
+    { "mest",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "mesz",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "swt",	tZONE,     -HOUR (1) },	/* Swedish Winter */
+    { "sst",	tDAYZONE,  -HOUR (1) },	/* Swedish Summer */
+    { "fwt",	tZONE,     -HOUR (1) },	/* French Winter */
+    { "fst",	tDAYZONE,  -HOUR (1) },	/* French Summer */
+    { "eet",	tZONE,     -HOUR (2) },	/* Eastern Europe, USSR Zone 1 */
+    { "bt",	tZONE,     -HOUR (3) },	/* Baghdad, USSR Zone 2 */
+#if 0
+    { "it",	tZONE,     -HOUR (3.5) },/* Iran */
+#endif
+    { "zp4",	tZONE,     -HOUR (4) },	/* USSR Zone 3 */
+    { "zp5",	tZONE,     -HOUR (5) },	/* USSR Zone 4 */
+#if 0
+    { "ist",	tZONE,     -HOUR (5.5) },/* Indian Standard */
+#endif
+    { "zp6",	tZONE,     -HOUR (6) },	/* USSR Zone 5 */
+#if	0
+    /* For completeness.  NST is also Newfoundland Standard, and SST is
+     * also Swedish Summer. */
+    { "nst",	tZONE,     -HOUR (6.5) },/* North Sumatra */
+    { "sst",	tZONE,     -HOUR (7) },	/* South Sumatra, USSR Zone 6 */
+#endif	/* 0 */
+    { "wast",	tZONE,     -HOUR (7) },	/* West Australian Standard */
+    { "wadt",	tDAYZONE,  -HOUR (7) },	/* West Australian Daylight */
+#if 0
+    { "jt",	tZONE,     -HOUR (7.5) },/* Java (3pm in Cronusland!) */
+#endif
+    { "cct",	tZONE,     -HOUR (8) },	/* China Coast, USSR Zone 7 */
+    { "jst",	tZONE,     -HOUR (9) },	/* Japan Standard, USSR Zone 8 */
+#if 0
+    { "cast",	tZONE,     -HOUR (9.5) },/* Central Australian Standard */
+    { "cadt",	tDAYZONE,  -HOUR (9.5) },/* Central Australian Daylight */
+#endif
+    { "east",	tZONE,     -HOUR (10) },	/* Eastern Australian Standard */
+    { "eadt",	tDAYZONE,  -HOUR (10) },	/* Eastern Australian Daylight */
+    { "gst",	tZONE,     -HOUR (10) },	/* Guam Standard, USSR Zone 9 */
+    { "nzt",	tZONE,     -HOUR (12) },	/* New Zealand */
+    { "nzst",	tZONE,     -HOUR (12) },	/* New Zealand Standard */
+    { "nzdt",	tDAYZONE,  -HOUR (12) },	/* New Zealand Daylight */
+    { "idle",	tZONE,     -HOUR (12) },	/* International Date Line East */
+    {  NULL, 0, 0  }
+};
+
+/* Military timezone table. */
+static TABLE const MilitaryTable[] = {
+    { "a",	tZONE,	HOUR (  1) },
+    { "b",	tZONE,	HOUR (  2) },
+    { "c",	tZONE,	HOUR (  3) },
+    { "d",	tZONE,	HOUR (  4) },
+    { "e",	tZONE,	HOUR (  5) },
+    { "f",	tZONE,	HOUR (  6) },
+    { "g",	tZONE,	HOUR (  7) },
+    { "h",	tZONE,	HOUR (  8) },
+    { "i",	tZONE,	HOUR (  9) },
+    { "k",	tZONE,	HOUR ( 10) },
+    { "l",	tZONE,	HOUR ( 11) },
+    { "m",	tZONE,	HOUR ( 12) },
+    { "n",	tZONE,	HOUR (- 1) },
+    { "o",	tZONE,	HOUR (- 2) },
+    { "p",	tZONE,	HOUR (- 3) },
+    { "q",	tZONE,	HOUR (- 4) },
+    { "r",	tZONE,	HOUR (- 5) },
+    { "s",	tZONE,	HOUR (- 6) },
+    { "t",	tZONE,	HOUR (- 7) },
+    { "u",	tZONE,	HOUR (- 8) },
+    { "v",	tZONE,	HOUR (- 9) },
+    { "w",	tZONE,	HOUR (-10) },
+    { "x",	tZONE,	HOUR (-11) },
+    { "y",	tZONE,	HOUR (-12) },
+    { "z",	tZONE,	HOUR (  0) },
+    { NULL, 0, 0 }
+};
+
+
+
+
+/* ARGSUSED */
+static int
+yyerror (char *s ATTRIBUTE_UNUSED)
+{
+  return 0;
+}
+
+static int
+ToHour (int Hours, MERIDIAN Meridian)
+{
+  switch (Meridian)
+    {
+    case MER24:
+      if (Hours < 0 || Hours > 23)
+	return -1;
+      return Hours;
+    case MERam:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours;
+    case MERpm:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours + 12;
+    default:
+      abort ();
+    }
+  /* NOTREACHED */
+}
+
+static int
+ToYear (int Year)
+{
+  if (Year < 0)
+    Year = -Year;
+
+  /* XPG4 suggests that years 00-68 map to 2000-2068, and
+     years 69-99 map to 1969-1999.  */
+  if (Year < 69)
+    Year += 2000;
+  else if (Year < 100)
+    Year += 1900;
+
+  return Year;
+}
+
+static int
+LookupWord (char *buff)
+{
+  register char *p;
+  register char *q;
+  register const TABLE *tp;
+  int i;
+  int abbrev;
+
+  /* Make it lowercase. */
+  for (p = buff; *p; p++)
+    if (ISUPPER ((unsigned char) *p))
+      *p = tolower ((unsigned char) *p);
+
+  if (strcmp (buff, "am") == 0 || strcmp (buff, "a.m.") == 0)
+    {
+      yylval.Meridian = MERam;
+      return tMERIDIAN;
+    }
+  if (strcmp (buff, "pm") == 0 || strcmp (buff, "p.m.") == 0)
+    {
+      yylval.Meridian = MERpm;
+      return tMERIDIAN;
+    }
+
+  /* See if we have an abbreviation for a month. */
+  if (strlen (buff) == 3)
+    abbrev = 1;
+  else if (strlen (buff) == 4 && buff[3] == '.')
+    {
+      abbrev = 1;
+      buff[3] = '\0';
+    }
+  else
+    abbrev = 0;
+
+  for (tp = MonthDayTable; tp->name; tp++)
+    {
+      if (abbrev)
+	{
+	  if (strncmp (buff, tp->name, 3) == 0)
+	    {
+	      yylval.Number = tp->value;
+	      return tp->type;
+	    }
+	}
+      else if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+    }
+
+  for (tp = TimezoneTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  if (strcmp (buff, "dst") == 0)
+    return tDST;
+
+  for (tp = UnitsTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Strip off any plural and try the units table again. */
+  i = strlen (buff) - 1;
+  if (buff[i] == 's')
+    {
+      buff[i] = '\0';
+      for (tp = UnitsTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+      buff[i] = 's';		/* Put back for "this" in OtherTable. */
+    }
+
+  for (tp = OtherTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Military timezones. */
+  if (buff[1] == '\0' && ISALPHA ((unsigned char) *buff))
+    {
+      for (tp = MilitaryTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+    }
+
+  /* Drop out any periods and try the timezone table again. */
+  for (i = 0, p = q = buff; *q; q++)
+    if (*q != '.')
+      *p++ = *q;
+    else
+      i++;
+  *p = '\0';
+  if (i)
+    for (tp = TimezoneTable; tp->name; tp++)
+      if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+
+  return tID;
+}
+
+static int
+yylex ()
+{
+  register unsigned char c;
+  register char *p;
+  char buff[20];
+  int Count;
+  int sign;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *yyInput))
+	yyInput++;
+
+      if (ISDIGIT (c = *yyInput) || c == '-' || c == '+')
+	{
+	  if (c == '-' || c == '+')
+	    {
+	      sign = c == '-' ? -1 : 1;
+	      if (!ISDIGIT (*++yyInput))
+		/* skip the '-' sign */
+		continue;
+	    }
+	  else
+	    sign = 0;
+	  for (yylval.Number = 0; ISDIGIT (c = *yyInput++);)
+	    yylval.Number = 10 * yylval.Number + c - '0';
+	  yyInput--;
+	  if (sign < 0)
+	    yylval.Number = -yylval.Number;
+	  return sign ? tSNUMBER : tUNUMBER;
+	}
+      if (ISALPHA (c))
+	{
+	  for (p = buff; (c = *yyInput++, ISALPHA (c)) || c == '.';)
+	    if (p < &buff[sizeof buff - 1])
+	      *p++ = c;
+	  *p = '\0';
+	  yyInput--;
+	  return LookupWord (buff);
+	}
+      if (c != '(')
+	return *yyInput++;
+      Count = 0;
+      do
+	{
+	  c = *yyInput++;
+	  if (c == '\0')
+	    return c;
+	  if (c == '(')
+	    Count++;
+	  else if (c == ')')
+	    Count--;
+	}
+      while (Count > 0);
+    }
+}
+
+#define TM_YEAR_ORIGIN 1900
+
+/* Yield A - B, measured in seconds.  */
+static long
+difftm (struct tm *a, struct tm *b)
+{
+  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
+  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
+  long days = (
+  /* difference in day of year */
+		a->tm_yday - b->tm_yday
+  /* + intervening leap days */
+		+ ((ay >> 2) - (by >> 2))
+		- (ay / 100 - by / 100)
+		+ ((ay / 100 >> 2) - (by / 100 >> 2))
+  /* + difference in years * 365 */
+		+ (long) (ay - by) * 365
+  );
+  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+	  + (a->tm_sec - b->tm_sec));
+}
+
+time_t
+get_date (const char *p, const time_t *now)
+{
+  struct tm tm, tm0, *tmp;
+  time_t Start;
+
+  yyInput = p;
+  Start = now ? *now : time ((time_t *) NULL);
+  tmp = localtime (&Start);
+  if (!tmp)
+    return -1;
+  yyYear = tmp->tm_year + TM_YEAR_ORIGIN;
+  yyMonth = tmp->tm_mon + 1;
+  yyDay = tmp->tm_mday;
+  yyHour = tmp->tm_hour;
+  yyMinutes = tmp->tm_min;
+  yySeconds = tmp->tm_sec;
+  tm.tm_isdst = tmp->tm_isdst;
+  yyMeridian = MER24;
+  yyRelSeconds = 0;
+  yyRelMinutes = 0;
+  yyRelHour = 0;
+  yyRelDay = 0;
+  yyRelMonth = 0;
+  yyRelYear = 0;
+  yyHaveDate = 0;
+  yyHaveDay = 0;
+  yyHaveRel = 0;
+  yyHaveTime = 0;
+  yyHaveZone = 0;
+
+  if (yyparse ()
+      || yyHaveTime > 1 || yyHaveZone > 1 || yyHaveDate > 1 || yyHaveDay > 1)
+    return -1;
+
+  tm.tm_year = ToYear (yyYear) - TM_YEAR_ORIGIN + yyRelYear;
+  tm.tm_mon = yyMonth - 1 + yyRelMonth;
+  tm.tm_mday = yyDay + yyRelDay;
+  if (yyHaveTime || (yyHaveRel && !yyHaveDate && !yyHaveDay))
+    {
+      tm.tm_hour = ToHour (yyHour, yyMeridian);
+      if (tm.tm_hour < 0)
+	return -1;
+      tm.tm_min = yyMinutes;
+      tm.tm_sec = yySeconds;
+    }
+  else
+    {
+      tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+    }
+  tm.tm_hour += yyRelHour;
+  tm.tm_min += yyRelMinutes;
+  tm.tm_sec += yyRelSeconds;
+
+  /* Let mktime deduce tm_isdst if we have an absolute timestamp,
+     or if the relative timestamp mentions days, months, or years.  */
+  if (yyHaveDate | yyHaveDay | yyHaveTime | yyRelDay | yyRelMonth | yyRelYear)
+    tm.tm_isdst = -1;
+
+  tm0 = tm;
+
+  Start = mktime (&tm);
+
+  if (Start == (time_t) -1)
+    {
+
+      /* Guard against falsely reporting errors near the time_t boundaries
+         when parsing times in other time zones.  For example, if the min
+         time_t value is 1970-01-01 00:00:00 UTC and we are 8 hours ahead
+         of UTC, then the min localtime value is 1970-01-01 08:00:00; if
+         we apply mktime to 1970-01-01 00:00:00 we will get an error, so
+         we apply mktime to 1970-01-02 08:00:00 instead and adjust the time
+         zone by 24 hours to compensate.  This algorithm assumes that
+         there is no DST transition within a day of the time_t boundaries.  */
+      if (yyHaveZone)
+	{
+	  tm = tm0;
+	  if (tm.tm_year <= EPOCH - TM_YEAR_ORIGIN)
+	    {
+	      tm.tm_mday++;
+	      yyTimezone -= 24 * 60;
+	    }
+	  else
+	    {
+	      tm.tm_mday--;
+	      yyTimezone += 24 * 60;
+	    }
+	  Start = mktime (&tm);
+	}
+
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveDay && !yyHaveDate)
+    {
+      tm.tm_mday += ((yyDayNumber - tm.tm_wday + 7) % 7
+		     + 7 * (yyDayOrdinal - (0 < yyDayOrdinal)));
+      Start = mktime (&tm);
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveZone)
+    {
+      long delta;
+      struct tm *gmt = gmtime (&Start);
+      if (!gmt)
+	return -1;
+      delta = yyTimezone * 60L + difftm (&tm, gmt);
+      if ((Start + delta < Start) != (delta < 0))
+	return -1;		/* time_t overflow */
+      Start += delta;
+    }
+
+  return Start;
+}
+
+#if	defined (TEST)
+
+/* ARGSUSED */
+int
+main (ac, av)
+     int ac;
+     char *av[];
+{
+  char buff[MAX_BUFF_LEN + 1];
+  time_t d;
+
+  (void) printf ("Enter date, or blank line to exit.\n\t> ");
+  (void) fflush (stdout);
+
+  buff[MAX_BUFF_LEN] = 0;
+  while (fgets (buff, MAX_BUFF_LEN, stdin) && buff[0])
+    {
+      d = get_date (buff, (time_t *) NULL);
+      if (d == -1)
+	(void) printf ("Bad format - couldn't convert.\n");
+      else
+	(void) printf ("%s", ctime (&d));
+      (void) printf ("\t> ");
+      (void) fflush (stdout);
+    }
+  exit (0);
+  /* NOTREACHED */
+}
+#endif /* defined (TEST) */
diff --git a/getdate.h b/getdate.h
new file mode 100644
index 0000000..a190d2d
--- /dev/null
+++ b/getdate.h
@@ -0,0 +1,28 @@
+/*  Copyright (C) 1995 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA. */
+
+/* Modified from the original to add stdlib.h and string.h */
+
+#ifndef GOT_GETDATE_H
+#define GOT_GETDATE_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+time_t get_date (const char *p, const time_t *now);
+
+#endif /* GOT_GETDATE_H */
diff --git a/getdate.y b/getdate.y
new file mode 100644
index 0000000..47d368d
--- /dev/null
+++ b/getdate.y
@@ -0,0 +1,1039 @@
+%{
+/*
+**  Originally written by Steven M. Bellovin <smb@research.att.com> while
+**  at the University of North Carolina at Chapel Hill.  Later tweaked by
+**  a couple of people on Usenet.  Completely overhauled by Rich $alz
+**  <rsalz@bbn.com> and Jim Berets <jberets@bbn.com> in August, 1990.
+**
+**  This code is in the public domain and has no copyright.
+*/
+
+#include "config.h"
+
+/* Since the code of getdate.y is not included in the Emacs executable
+   itself, there is no need to #define static in this file.  Even if
+   the code were included in the Emacs executable, it probably
+   wouldn't do any harm to #undef it here; this will only cause
+   problems if we try to write to a static variable, which I don't
+   think this code needs to do.  */
+#ifdef emacs
+# undef static
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+
+#if HAVE_STDLIB_H
+# include <stdlib.h> /* for `free'; used by Bison 1.27 */
+#endif
+
+#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
+# define IN_CTYPE_DOMAIN(c) 1
+#else
+# define IN_CTYPE_DOMAIN(c) isascii(c)
+#endif
+
+#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
+#define ISALPHA(c) (IN_CTYPE_DOMAIN (c) && isalpha (c))
+#define ISUPPER(c) (IN_CTYPE_DOMAIN (c) && isupper (c))
+#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+
+/* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
+   only '0' through '9' are digits.  Prefer ISDIGIT to ISDIGIT_LOCALE unless
+   it's important to use the locale's definition of `digit' even when the
+   host does not conform to Posix.  */
+#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
+
+#if defined (STDC_HEADERS) || defined (USG)
+# include <string.h>
+#endif
+
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
+# define __attribute__(x)
+#endif
+
+#ifndef ATTRIBUTE_UNUSED
+# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#endif
+
+/* Some old versions of bison generate parsers that use bcopy.
+   That loses on systems that don't provide the function, so we have
+   to redefine it here.  */
+#if !defined (HAVE_BCOPY) && defined (HAVE_MEMCPY) && !defined (bcopy)
+# define bcopy(from, to, len) memcpy ((to), (from), (len))
+#endif
+
+/* Remap normal yacc parser interface names (yyparse, yylex, yyerror, etc),
+   as well as gratuitiously global symbol names, so we can have multiple
+   yacc generated parsers in the same program.  Note that these are only
+   the variables produced by yacc.  If other parser generators (bison,
+   byacc, etc) produce additional global names that conflict at link time,
+   then those parser generators need to be fixed instead of adding those
+   names to this list. */
+
+#define yymaxdepth gd_maxdepth
+#define yyparse gd_parse
+#define yylex   gd_lex
+#define yyerror gd_error
+#define yylval  gd_lval
+#define yychar  gd_char
+#define yydebug gd_debug
+#define yypact  gd_pact
+#define yyr1    gd_r1
+#define yyr2    gd_r2
+#define yydef   gd_def
+#define yychk   gd_chk
+#define yypgo   gd_pgo
+#define yyact   gd_act
+#define yyexca  gd_exca
+#define yyerrflag gd_errflag
+#define yynerrs gd_nerrs
+#define yyps    gd_ps
+#define yypv    gd_pv
+#define yys     gd_s
+#define yy_yys  gd_yys
+#define yystate gd_state
+#define yytmp   gd_tmp
+#define yyv     gd_v
+#define yy_yyv  gd_yyv
+#define yyval   gd_val
+#define yylloc  gd_lloc
+#define yyreds  gd_reds          /* With YYDEBUG defined */
+#define yytoks  gd_toks          /* With YYDEBUG defined */
+#define yylhs   gd_yylhs
+#define yylen   gd_yylen
+#define yydefred gd_yydefred
+#define yydgoto gd_yydgoto
+#define yysindex gd_yysindex
+#define yyrindex gd_yyrindex
+#define yygindex gd_yygindex
+#define yytable  gd_yytable
+#define yycheck  gd_yycheck
+
+static int yylex (void);
+static int yyerror (char *s);
+
+#define EPOCH		1970
+#define HOUR(x)		((x) * 60)
+
+#define MAX_BUFF_LEN    128   /* size of buffer to read the date into */
+
+/*
+**  An entry in the lexical lookup table.
+*/
+typedef struct _TABLE {
+    const char	*name;
+    int		type;
+    int		value;
+} TABLE;
+
+
+/*
+**  Meridian:  am, pm, or 24-hour style.
+*/
+typedef enum _MERIDIAN {
+    MERam, MERpm, MER24
+} MERIDIAN;
+
+
+/*
+**  Global variables.  We could get rid of most of these by using a good
+**  union as the yacc stack.  (This routine was originally written before
+**  yacc had the %union construct.)  Maybe someday; right now we only use
+**  the %union very rarely.
+*/
+static const char	*yyInput;
+static int	yyDayOrdinal;
+static int	yyDayNumber;
+static int	yyHaveDate;
+static int	yyHaveDay;
+static int	yyHaveRel;
+static int	yyHaveTime;
+static int	yyHaveZone;
+static int	yyTimezone;
+static int	yyDay;
+static int	yyHour;
+static int	yyMinutes;
+static int	yyMonth;
+static int	yySeconds;
+static int	yyYear;
+static MERIDIAN	yyMeridian;
+static int	yyRelDay;
+static int	yyRelHour;
+static int	yyRelMinutes;
+static int	yyRelMonth;
+static int	yyRelSeconds;
+static int	yyRelYear;
+
+%}
+
+/* This grammar has 13 shift/reduce conflicts. */
+%expect 13
+
+%union {
+    int			Number;
+    enum _MERIDIAN	Meridian;
+}
+
+%token	tAGO tDAY tDAY_UNIT tDAYZONE tDST tHOUR_UNIT tID
+%token	tMERIDIAN tMINUTE_UNIT tMONTH tMONTH_UNIT
+%token	tSEC_UNIT tSNUMBER tUNUMBER tYEAR_UNIT tZONE
+
+%type	<Number>	tDAY tDAY_UNIT tDAYZONE tHOUR_UNIT tMINUTE_UNIT
+%type	<Number>	tMONTH tMONTH_UNIT
+%type	<Number>	tSEC_UNIT tSNUMBER tUNUMBER tYEAR_UNIT tZONE
+%type	<Meridian>	tMERIDIAN o_merid
+
+%%
+
+spec	: /* NULL */
+	| spec item
+	;
+
+item	: time {
+	    yyHaveTime++;
+	}
+	| zone {
+	    yyHaveZone++;
+	}
+	| date {
+	    yyHaveDate++;
+	}
+	| day {
+	    yyHaveDay++;
+	}
+	| rel {
+	    yyHaveRel++;
+	}
+	| number
+	;
+
+time	: tUNUMBER tMERIDIAN {
+	    yyHour = $1;
+	    yyMinutes = 0;
+	    yySeconds = 0;
+	    yyMeridian = $2;
+	}
+	| tUNUMBER ':' tUNUMBER o_merid {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = 0;
+	    yyMeridian = $4;
+	}
+	| tUNUMBER ':' tUNUMBER tSNUMBER {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ($4 < 0
+			  ? -$4 % 100 + (-$4 / 100) * 60
+			  : - ($4 % 100 + ($4 / 100) * 60));
+	}
+	| tUNUMBER ':' tUNUMBER ':' tUNUMBER o_merid {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = $5;
+	    yyMeridian = $6;
+	}
+	| tUNUMBER ':' tUNUMBER ':' tUNUMBER tSNUMBER {
+	    yyHour = $1;
+	    yyMinutes = $3;
+	    yySeconds = $5;
+	    yyMeridian = MER24;
+	    yyHaveZone++;
+	    yyTimezone = ($6 < 0
+			  ? -$6 % 100 + (-$6 / 100) * 60
+			  : - ($6 % 100 + ($6 / 100) * 60));
+	}
+	;
+
+zone	: tZONE {
+	    yyTimezone = $1;
+	}
+	| tDAYZONE {
+	    yyTimezone = $1 - 60;
+	}
+	|
+	  tZONE tDST {
+	    yyTimezone = $1 - 60;
+	}
+	;
+
+day	: tDAY {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = $1;
+	}
+	| tDAY ',' {
+	    yyDayOrdinal = 1;
+	    yyDayNumber = $1;
+	}
+	| tUNUMBER tDAY {
+	    yyDayOrdinal = $1;
+	    yyDayNumber = $2;
+	}
+	;
+
+date	: tUNUMBER '/' tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $3;
+	}
+	| tUNUMBER '/' tUNUMBER '/' tUNUMBER {
+	  /* Interpret as YYYY/MM/DD if $1 >= 1000, otherwise as MM/DD/YY.
+	     The goal in recognizing YYYY/MM/DD is solely to support legacy
+	     machine-generated dates like those in an RCS log listing.  If
+	     you want portability, use the ISO 8601 format.  */
+	  if ($1 >= 1000)
+	    {
+	      yyYear = $1;
+	      yyMonth = $3;
+	      yyDay = $5;
+	    }
+	  else
+	    {
+	      yyMonth = $1;
+	      yyDay = $3;
+	      yyYear = $5;
+	    }
+	}
+	| tUNUMBER tSNUMBER tSNUMBER {
+	    /* ISO 8601 format.  yyyy-mm-dd.  */
+	    yyYear = $1;
+	    yyMonth = -$2;
+	    yyDay = -$3;
+	}
+	| tUNUMBER tMONTH tSNUMBER {
+	    /* e.g. 17-JUN-1992.  */
+	    yyDay = $1;
+	    yyMonth = $2;
+	    yyYear = -$3;
+	}
+	| tMONTH tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $2;
+	}
+	| tMONTH tUNUMBER ',' tUNUMBER {
+	    yyMonth = $1;
+	    yyDay = $2;
+	    yyYear = $4;
+	}
+	| tUNUMBER tMONTH {
+	    yyMonth = $2;
+	    yyDay = $1;
+	}
+	| tUNUMBER tMONTH tUNUMBER {
+	    yyMonth = $2;
+	    yyDay = $1;
+	    yyYear = $3;
+	}
+	;
+
+rel	: relunit tAGO {
+	    yyRelSeconds = -yyRelSeconds;
+	    yyRelMinutes = -yyRelMinutes;
+	    yyRelHour = -yyRelHour;
+	    yyRelDay = -yyRelDay;
+	    yyRelMonth = -yyRelMonth;
+	    yyRelYear = -yyRelYear;
+	}
+	| relunit
+	;
+
+relunit	: tUNUMBER tYEAR_UNIT {
+	    yyRelYear += $1 * $2;
+	}
+	| tSNUMBER tYEAR_UNIT {
+	    yyRelYear += $1 * $2;
+	}
+	| tYEAR_UNIT {
+	    yyRelYear += $1;
+	}
+	| tUNUMBER tMONTH_UNIT {
+	    yyRelMonth += $1 * $2;
+	}
+	| tSNUMBER tMONTH_UNIT {
+	    yyRelMonth += $1 * $2;
+	}
+	| tMONTH_UNIT {
+	    yyRelMonth += $1;
+	}
+	| tUNUMBER tDAY_UNIT {
+	    yyRelDay += $1 * $2;
+	}
+	| tSNUMBER tDAY_UNIT {
+	    yyRelDay += $1 * $2;
+	}
+	| tDAY_UNIT {
+	    yyRelDay += $1;
+	}
+	| tUNUMBER tHOUR_UNIT {
+	    yyRelHour += $1 * $2;
+	}
+	| tSNUMBER tHOUR_UNIT {
+	    yyRelHour += $1 * $2;
+	}
+	| tHOUR_UNIT {
+	    yyRelHour += $1;
+	}
+	| tUNUMBER tMINUTE_UNIT {
+	    yyRelMinutes += $1 * $2;
+	}
+	| tSNUMBER tMINUTE_UNIT {
+	    yyRelMinutes += $1 * $2;
+	}
+	| tMINUTE_UNIT {
+	    yyRelMinutes += $1;
+	}
+	| tUNUMBER tSEC_UNIT {
+	    yyRelSeconds += $1 * $2;
+	}
+	| tSNUMBER tSEC_UNIT {
+	    yyRelSeconds += $1 * $2;
+	}
+	| tSEC_UNIT {
+	    yyRelSeconds += $1;
+	}
+	;
+
+number	: tUNUMBER
+          {
+	    if (yyHaveTime && yyHaveDate && !yyHaveRel)
+	      yyYear = $1;
+	    else
+	      {
+		if ($1>10000)
+		  {
+		    yyHaveDate++;
+		    yyDay= ($1)%100;
+		    yyMonth= ($1/100)%100;
+		    yyYear = $1/10000;
+		  }
+		else
+		  {
+		    yyHaveTime++;
+		    if ($1 < 100)
+		      {
+			yyHour = $1;
+			yyMinutes = 0;
+		      }
+		    else
+		      {
+		    	yyHour = $1 / 100;
+		    	yyMinutes = $1 % 100;
+		      }
+		    yySeconds = 0;
+		    yyMeridian = MER24;
+		  }
+	      }
+	  }
+	;
+
+o_merid	: /* NULL */
+	  {
+	    $$ = MER24;
+	  }
+	| tMERIDIAN
+	  {
+	    $$ = $1;
+	  }
+	;
+
+%%
+
+/* Include this file down here because bison inserts code above which
+   may define-away `const'.  We want the prototype for get_date to have
+   the same signature as the function definition does. */
+#include "getdate.h"
+
+extern struct tm	*gmtime (const time_t *timep);
+extern struct tm	*localtime (const time_t *timep);
+extern time_t		mktime (struct tm *tm);
+
+/* Month and day table. */
+static TABLE const MonthDayTable[] = {
+    { "january",	tMONTH,  1 },
+    { "february",	tMONTH,  2 },
+    { "march",		tMONTH,  3 },
+    { "april",		tMONTH,  4 },
+    { "may",		tMONTH,  5 },
+    { "june",		tMONTH,  6 },
+    { "july",		tMONTH,  7 },
+    { "august",		tMONTH,  8 },
+    { "september",	tMONTH,  9 },
+    { "sept",		tMONTH,  9 },
+    { "october",	tMONTH, 10 },
+    { "november",	tMONTH, 11 },
+    { "december",	tMONTH, 12 },
+    { "sunday",		tDAY, 0 },
+    { "monday",		tDAY, 1 },
+    { "tuesday",	tDAY, 2 },
+    { "tues",		tDAY, 2 },
+    { "wednesday",	tDAY, 3 },
+    { "wednes",		tDAY, 3 },
+    { "thursday",	tDAY, 4 },
+    { "thur",		tDAY, 4 },
+    { "thurs",		tDAY, 4 },
+    { "friday",		tDAY, 5 },
+    { "saturday",	tDAY, 6 },
+    { NULL, 0, 0 }
+};
+
+/* Time units table. */
+static TABLE const UnitsTable[] = {
+    { "year",		tYEAR_UNIT,	1 },
+    { "month",		tMONTH_UNIT,	1 },
+    { "fortnight",	tDAY_UNIT,	14 },
+    { "week",		tDAY_UNIT,	7 },
+    { "day",		tDAY_UNIT,	1 },
+    { "hour",		tHOUR_UNIT,	1 },
+    { "minute",		tMINUTE_UNIT,	1 },
+    { "min",		tMINUTE_UNIT,	1 },
+    { "second",		tSEC_UNIT,	1 },
+    { "sec",		tSEC_UNIT,	1 },
+    { NULL, 0, 0 }
+};
+
+/* Assorted relative-time words. */
+static TABLE const OtherTable[] = {
+    { "tomorrow",	tMINUTE_UNIT,	1 * 24 * 60 },
+    { "yesterday",	tMINUTE_UNIT,	-1 * 24 * 60 },
+    { "today",		tMINUTE_UNIT,	0 },
+    { "now",		tMINUTE_UNIT,	0 },
+    { "last",		tUNUMBER,	-1 },
+    { "this",		tMINUTE_UNIT,	0 },
+    { "next",		tUNUMBER,	1 },
+    { "first",		tUNUMBER,	1 },
+/*  { "second",		tUNUMBER,	2 }, */
+    { "third",		tUNUMBER,	3 },
+    { "fourth",		tUNUMBER,	4 },
+    { "fifth",		tUNUMBER,	5 },
+    { "sixth",		tUNUMBER,	6 },
+    { "seventh",	tUNUMBER,	7 },
+    { "eighth",		tUNUMBER,	8 },
+    { "ninth",		tUNUMBER,	9 },
+    { "tenth",		tUNUMBER,	10 },
+    { "eleventh",	tUNUMBER,	11 },
+    { "twelfth",	tUNUMBER,	12 },
+    { "ago",		tAGO,	1 },
+    { NULL, 0, 0 }
+};
+
+/* The timezone table. */
+static TABLE const TimezoneTable[] = {
+    { "gmt",	tZONE,     HOUR ( 0) },	/* Greenwich Mean */
+    { "ut",	tZONE,     HOUR ( 0) },	/* Universal (Coordinated) */
+    { "utc",	tZONE,     HOUR ( 0) },
+    { "wet",	tZONE,     HOUR ( 0) },	/* Western European */
+    { "bst",	tDAYZONE,  HOUR ( 0) },	/* British Summer */
+    { "wat",	tZONE,     HOUR ( 1) },	/* West Africa */
+    { "at",	tZONE,     HOUR ( 2) },	/* Azores */
+#if	0
+    /* For completeness.  BST is also British Summer, and GST is
+     * also Guam Standard. */
+    { "bst",	tZONE,     HOUR ( 3) },	/* Brazil Standard */
+    { "gst",	tZONE,     HOUR ( 3) },	/* Greenland Standard */
+#endif
+#if 0
+    { "nft",	tZONE,     HOUR (3.5) },	/* Newfoundland */
+    { "nst",	tZONE,     HOUR (3.5) },	/* Newfoundland Standard */
+    { "ndt",	tDAYZONE,  HOUR (3.5) },	/* Newfoundland Daylight */
+#endif
+    { "ast",	tZONE,     HOUR ( 4) },	/* Atlantic Standard */
+    { "adt",	tDAYZONE,  HOUR ( 4) },	/* Atlantic Daylight */
+    { "est",	tZONE,     HOUR ( 5) },	/* Eastern Standard */
+    { "edt",	tDAYZONE,  HOUR ( 5) },	/* Eastern Daylight */
+    { "cst",	tZONE,     HOUR ( 6) },	/* Central Standard */
+    { "cdt",	tDAYZONE,  HOUR ( 6) },	/* Central Daylight */
+    { "mst",	tZONE,     HOUR ( 7) },	/* Mountain Standard */
+    { "mdt",	tDAYZONE,  HOUR ( 7) },	/* Mountain Daylight */
+    { "pst",	tZONE,     HOUR ( 8) },	/* Pacific Standard */
+    { "pdt",	tDAYZONE,  HOUR ( 8) },	/* Pacific Daylight */
+    { "yst",	tZONE,     HOUR ( 9) },	/* Yukon Standard */
+    { "ydt",	tDAYZONE,  HOUR ( 9) },	/* Yukon Daylight */
+    { "hst",	tZONE,     HOUR (10) },	/* Hawaii Standard */
+    { "hdt",	tDAYZONE,  HOUR (10) },	/* Hawaii Daylight */
+    { "cat",	tZONE,     HOUR (10) },	/* Central Alaska */
+    { "ahst",	tZONE,     HOUR (10) },	/* Alaska-Hawaii Standard */
+    { "nt",	tZONE,     HOUR (11) },	/* Nome */
+    { "idlw",	tZONE,     HOUR (12) },	/* International Date Line West */
+    { "cet",	tZONE,     -HOUR (1) },	/* Central European */
+    { "met",	tZONE,     -HOUR (1) },	/* Middle European */
+    { "mewt",	tZONE,     -HOUR (1) },	/* Middle European Winter */
+    { "mest",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "mesz",	tDAYZONE,  -HOUR (1) },	/* Middle European Summer */
+    { "swt",	tZONE,     -HOUR (1) },	/* Swedish Winter */
+    { "sst",	tDAYZONE,  -HOUR (1) },	/* Swedish Summer */
+    { "fwt",	tZONE,     -HOUR (1) },	/* French Winter */
+    { "fst",	tDAYZONE,  -HOUR (1) },	/* French Summer */
+    { "eet",	tZONE,     -HOUR (2) },	/* Eastern Europe, USSR Zone 1 */
+    { "bt",	tZONE,     -HOUR (3) },	/* Baghdad, USSR Zone 2 */
+#if 0
+    { "it",	tZONE,     -HOUR (3.5) },/* Iran */
+#endif
+    { "zp4",	tZONE,     -HOUR (4) },	/* USSR Zone 3 */
+    { "zp5",	tZONE,     -HOUR (5) },	/* USSR Zone 4 */
+#if 0
+    { "ist",	tZONE,     -HOUR (5.5) },/* Indian Standard */
+#endif
+    { "zp6",	tZONE,     -HOUR (6) },	/* USSR Zone 5 */
+#if	0
+    /* For completeness.  NST is also Newfoundland Standard, and SST is
+     * also Swedish Summer. */
+    { "nst",	tZONE,     -HOUR (6.5) },/* North Sumatra */
+    { "sst",	tZONE,     -HOUR (7) },	/* South Sumatra, USSR Zone 6 */
+#endif	/* 0 */
+    { "wast",	tZONE,     -HOUR (7) },	/* West Australian Standard */
+    { "wadt",	tDAYZONE,  -HOUR (7) },	/* West Australian Daylight */
+#if 0
+    { "jt",	tZONE,     -HOUR (7.5) },/* Java (3pm in Cronusland!) */
+#endif
+    { "cct",	tZONE,     -HOUR (8) },	/* China Coast, USSR Zone 7 */
+    { "jst",	tZONE,     -HOUR (9) },	/* Japan Standard, USSR Zone 8 */
+#if 0
+    { "cast",	tZONE,     -HOUR (9.5) },/* Central Australian Standard */
+    { "cadt",	tDAYZONE,  -HOUR (9.5) },/* Central Australian Daylight */
+#endif
+    { "east",	tZONE,     -HOUR (10) },	/* Eastern Australian Standard */
+    { "eadt",	tDAYZONE,  -HOUR (10) },	/* Eastern Australian Daylight */
+    { "gst",	tZONE,     -HOUR (10) },	/* Guam Standard, USSR Zone 9 */
+    { "nzt",	tZONE,     -HOUR (12) },	/* New Zealand */
+    { "nzst",	tZONE,     -HOUR (12) },	/* New Zealand Standard */
+    { "nzdt",	tDAYZONE,  -HOUR (12) },	/* New Zealand Daylight */
+    { "idle",	tZONE,     -HOUR (12) },	/* International Date Line East */
+    {  NULL, 0, 0  }
+};
+
+/* Military timezone table. */
+static TABLE const MilitaryTable[] = {
+    { "a",	tZONE,	HOUR (  1) },
+    { "b",	tZONE,	HOUR (  2) },
+    { "c",	tZONE,	HOUR (  3) },
+    { "d",	tZONE,	HOUR (  4) },
+    { "e",	tZONE,	HOUR (  5) },
+    { "f",	tZONE,	HOUR (  6) },
+    { "g",	tZONE,	HOUR (  7) },
+    { "h",	tZONE,	HOUR (  8) },
+    { "i",	tZONE,	HOUR (  9) },
+    { "k",	tZONE,	HOUR ( 10) },
+    { "l",	tZONE,	HOUR ( 11) },
+    { "m",	tZONE,	HOUR ( 12) },
+    { "n",	tZONE,	HOUR (- 1) },
+    { "o",	tZONE,	HOUR (- 2) },
+    { "p",	tZONE,	HOUR (- 3) },
+    { "q",	tZONE,	HOUR (- 4) },
+    { "r",	tZONE,	HOUR (- 5) },
+    { "s",	tZONE,	HOUR (- 6) },
+    { "t",	tZONE,	HOUR (- 7) },
+    { "u",	tZONE,	HOUR (- 8) },
+    { "v",	tZONE,	HOUR (- 9) },
+    { "w",	tZONE,	HOUR (-10) },
+    { "x",	tZONE,	HOUR (-11) },
+    { "y",	tZONE,	HOUR (-12) },
+    { "z",	tZONE,	HOUR (  0) },
+    { NULL, 0, 0 }
+};
+
+
+
+
+/* ARGSUSED */
+static int
+yyerror (char *s ATTRIBUTE_UNUSED)
+{
+  return 0;
+}
+
+static int
+ToHour (int Hours, MERIDIAN Meridian)
+{
+  switch (Meridian)
+    {
+    case MER24:
+      if (Hours < 0 || Hours > 23)
+	return -1;
+      return Hours;
+    case MERam:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours;
+    case MERpm:
+      if (Hours < 1 || Hours > 12)
+	return -1;
+      if (Hours == 12)
+	Hours = 0;
+      return Hours + 12;
+    default:
+      abort ();
+    }
+  /* NOTREACHED */
+}
+
+static int
+ToYear (int Year)
+{
+  if (Year < 0)
+    Year = -Year;
+
+  /* XPG4 suggests that years 00-68 map to 2000-2068, and
+     years 69-99 map to 1969-1999.  */
+  if (Year < 69)
+    Year += 2000;
+  else if (Year < 100)
+    Year += 1900;
+
+  return Year;
+}
+
+static int
+LookupWord (char *buff)
+{
+  register char *p;
+  register char *q;
+  register const TABLE *tp;
+  int i;
+  int abbrev;
+
+  /* Make it lowercase. */
+  for (p = buff; *p; p++)
+    if (ISUPPER ((unsigned char) *p))
+      *p = tolower ((unsigned char) *p);
+
+  if (strcmp (buff, "am") == 0 || strcmp (buff, "a.m.") == 0)
+    {
+      yylval.Meridian = MERam;
+      return tMERIDIAN;
+    }
+  if (strcmp (buff, "pm") == 0 || strcmp (buff, "p.m.") == 0)
+    {
+      yylval.Meridian = MERpm;
+      return tMERIDIAN;
+    }
+
+  /* See if we have an abbreviation for a month. */
+  if (strlen (buff) == 3)
+    abbrev = 1;
+  else if (strlen (buff) == 4 && buff[3] == '.')
+    {
+      abbrev = 1;
+      buff[3] = '\0';
+    }
+  else
+    abbrev = 0;
+
+  for (tp = MonthDayTable; tp->name; tp++)
+    {
+      if (abbrev)
+	{
+	  if (strncmp (buff, tp->name, 3) == 0)
+	    {
+	      yylval.Number = tp->value;
+	      return tp->type;
+	    }
+	}
+      else if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+    }
+
+  for (tp = TimezoneTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  if (strcmp (buff, "dst") == 0)
+    return tDST;
+
+  for (tp = UnitsTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Strip off any plural and try the units table again. */
+  i = strlen (buff) - 1;
+  if (buff[i] == 's')
+    {
+      buff[i] = '\0';
+      for (tp = UnitsTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+      buff[i] = 's';		/* Put back for "this" in OtherTable. */
+    }
+
+  for (tp = OtherTable; tp->name; tp++)
+    if (strcmp (buff, tp->name) == 0)
+      {
+	yylval.Number = tp->value;
+	return tp->type;
+      }
+
+  /* Military timezones. */
+  if (buff[1] == '\0' && ISALPHA ((unsigned char) *buff))
+    {
+      for (tp = MilitaryTable; tp->name; tp++)
+	if (strcmp (buff, tp->name) == 0)
+	  {
+	    yylval.Number = tp->value;
+	    return tp->type;
+	  }
+    }
+
+  /* Drop out any periods and try the timezone table again. */
+  for (i = 0, p = q = buff; *q; q++)
+    if (*q != '.')
+      *p++ = *q;
+    else
+      i++;
+  *p = '\0';
+  if (i)
+    for (tp = TimezoneTable; tp->name; tp++)
+      if (strcmp (buff, tp->name) == 0)
+	{
+	  yylval.Number = tp->value;
+	  return tp->type;
+	}
+
+  return tID;
+}
+
+static int
+yylex ()
+{
+  register unsigned char c;
+  register char *p;
+  char buff[20];
+  int Count;
+  int sign;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *yyInput))
+	yyInput++;
+
+      if (ISDIGIT (c = *yyInput) || c == '-' || c == '+')
+	{
+	  if (c == '-' || c == '+')
+	    {
+	      sign = c == '-' ? -1 : 1;
+	      if (!ISDIGIT (*++yyInput))
+		/* skip the '-' sign */
+		continue;
+	    }
+	  else
+	    sign = 0;
+	  for (yylval.Number = 0; ISDIGIT (c = *yyInput++);)
+	    yylval.Number = 10 * yylval.Number + c - '0';
+	  yyInput--;
+	  if (sign < 0)
+	    yylval.Number = -yylval.Number;
+	  return sign ? tSNUMBER : tUNUMBER;
+	}
+      if (ISALPHA (c))
+	{
+	  for (p = buff; (c = *yyInput++, ISALPHA (c)) || c == '.';)
+	    if (p < &buff[sizeof buff - 1])
+	      *p++ = c;
+	  *p = '\0';
+	  yyInput--;
+	  return LookupWord (buff);
+	}
+      if (c != '(')
+	return *yyInput++;
+      Count = 0;
+      do
+	{
+	  c = *yyInput++;
+	  if (c == '\0')
+	    return c;
+	  if (c == '(')
+	    Count++;
+	  else if (c == ')')
+	    Count--;
+	}
+      while (Count > 0);
+    }
+}
+
+#define TM_YEAR_ORIGIN 1900
+
+/* Yield A - B, measured in seconds.  */
+static long
+difftm (struct tm *a, struct tm *b)
+{
+  int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
+  int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
+  long days = (
+  /* difference in day of year */
+		a->tm_yday - b->tm_yday
+  /* + intervening leap days */
+		+ ((ay >> 2) - (by >> 2))
+		- (ay / 100 - by / 100)
+		+ ((ay / 100 >> 2) - (by / 100 >> 2))
+  /* + difference in years * 365 */
+		+ (long) (ay - by) * 365
+  );
+  return (60 * (60 * (24 * days + (a->tm_hour - b->tm_hour))
+		+ (a->tm_min - b->tm_min))
+	  + (a->tm_sec - b->tm_sec));
+}
+
+time_t
+get_date (const char *p, const time_t *now)
+{
+  struct tm tm, tm0, *tmp;
+  time_t Start;
+
+  yyInput = p;
+  Start = now ? *now : time ((time_t *) NULL);
+  tmp = localtime (&Start);
+  if (!tmp)
+    return -1;
+  yyYear = tmp->tm_year + TM_YEAR_ORIGIN;
+  yyMonth = tmp->tm_mon + 1;
+  yyDay = tmp->tm_mday;
+  yyHour = tmp->tm_hour;
+  yyMinutes = tmp->tm_min;
+  yySeconds = tmp->tm_sec;
+  tm.tm_isdst = tmp->tm_isdst;
+  yyMeridian = MER24;
+  yyRelSeconds = 0;
+  yyRelMinutes = 0;
+  yyRelHour = 0;
+  yyRelDay = 0;
+  yyRelMonth = 0;
+  yyRelYear = 0;
+  yyHaveDate = 0;
+  yyHaveDay = 0;
+  yyHaveRel = 0;
+  yyHaveTime = 0;
+  yyHaveZone = 0;
+
+  if (yyparse ()
+      || yyHaveTime > 1 || yyHaveZone > 1 || yyHaveDate > 1 || yyHaveDay > 1)
+    return -1;
+
+  tm.tm_year = ToYear (yyYear) - TM_YEAR_ORIGIN + yyRelYear;
+  tm.tm_mon = yyMonth - 1 + yyRelMonth;
+  tm.tm_mday = yyDay + yyRelDay;
+  if (yyHaveTime || (yyHaveRel && !yyHaveDate && !yyHaveDay))
+    {
+      tm.tm_hour = ToHour (yyHour, yyMeridian);
+      if (tm.tm_hour < 0)
+	return -1;
+      tm.tm_min = yyMinutes;
+      tm.tm_sec = yySeconds;
+    }
+  else
+    {
+      tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+    }
+  tm.tm_hour += yyRelHour;
+  tm.tm_min += yyRelMinutes;
+  tm.tm_sec += yyRelSeconds;
+
+  /* Let mktime deduce tm_isdst if we have an absolute timestamp,
+     or if the relative timestamp mentions days, months, or years.  */
+  if (yyHaveDate | yyHaveDay | yyHaveTime | yyRelDay | yyRelMonth | yyRelYear)
+    tm.tm_isdst = -1;
+
+  tm0 = tm;
+
+  Start = mktime (&tm);
+
+  if (Start == (time_t) -1)
+    {
+
+      /* Guard against falsely reporting errors near the time_t boundaries
+         when parsing times in other time zones.  For example, if the min
+         time_t value is 1970-01-01 00:00:00 UTC and we are 8 hours ahead
+         of UTC, then the min localtime value is 1970-01-01 08:00:00; if
+         we apply mktime to 1970-01-01 00:00:00 we will get an error, so
+         we apply mktime to 1970-01-02 08:00:00 instead and adjust the time
+         zone by 24 hours to compensate.  This algorithm assumes that
+         there is no DST transition within a day of the time_t boundaries.  */
+      if (yyHaveZone)
+	{
+	  tm = tm0;
+	  if (tm.tm_year <= EPOCH - TM_YEAR_ORIGIN)
+	    {
+	      tm.tm_mday++;
+	      yyTimezone -= 24 * 60;
+	    }
+	  else
+	    {
+	      tm.tm_mday--;
+	      yyTimezone += 24 * 60;
+	    }
+	  Start = mktime (&tm);
+	}
+
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveDay && !yyHaveDate)
+    {
+      tm.tm_mday += ((yyDayNumber - tm.tm_wday + 7) % 7
+		     + 7 * (yyDayOrdinal - (0 < yyDayOrdinal)));
+      Start = mktime (&tm);
+      if (Start == (time_t) -1)
+	return Start;
+    }
+
+  if (yyHaveZone)
+    {
+      long delta;
+      struct tm *gmt = gmtime (&Start);
+      if (!gmt)
+	return -1;
+      delta = yyTimezone * 60L + difftm (&tm, gmt);
+      if ((Start + delta < Start) != (delta < 0))
+	return -1;		/* time_t overflow */
+      Start += delta;
+    }
+
+  return Start;
+}
+
+#if	defined (TEST)
+
+/* ARGSUSED */
+int
+main (ac, av)
+     int ac;
+     char *av[];
+{
+  char buff[MAX_BUFF_LEN + 1];
+  time_t d;
+
+  (void) printf ("Enter date, or blank line to exit.\n\t> ");
+  (void) fflush (stdout);
+
+  buff[MAX_BUFF_LEN] = 0;
+  while (fgets (buff, MAX_BUFF_LEN, stdin) && buff[0])
+    {
+      d = get_date (buff, (time_t *) NULL);
+      if (d == -1)
+	(void) printf ("Bad format - couldn't convert.\n");
+      else
+	(void) printf ("%s", ctime (&d));
+      (void) printf ("\t> ");
+      (void) fflush (stdout);
+    }
+  exit (0);
+  /* NOTREACHED */
+}
+#endif /* defined (TEST) */
diff --git a/hash.h b/hash.h
new file mode 100644
index 0000000..39abf27
--- /dev/null
+++ b/hash.h
@@ -0,0 +1,57 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for crypto hashing.
+
+  */
+
+#ifndef GOT_HASH_H
+#define GOT_HASH_H
+
+/* length of hash values produced by SHA512 */
+#define MAX_HASH_LENGTH 64
+
+typedef enum {
+  HSH_INVALID = 0,
+  HSH_MD5 = 1,
+  HSH_SHA1 = 2,
+  HSH_SHA256 = 3,
+  HSH_SHA384 = 4,
+  HSH_SHA512 = 5,
+  HSH_SHA3_224 = 6,
+  HSH_SHA3_256 = 7,
+  HSH_SHA3_384 = 8,
+  HSH_SHA3_512 = 9,
+  HSH_TIGER = 10,
+  HSH_WHIRLPOOL = 11,
+  HSH_MD5_NONCRYPTO = 10000, /* For NTPv4 reference ID */
+} HSH_Algorithm;
+
+extern int HSH_GetHashId(HSH_Algorithm algorithm);
+
+extern int HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+                    unsigned char *out, int out_len);
+
+extern void HSH_Finalise(void);
+
+#endif
diff --git a/hash_gnutls.c b/hash_gnutls.c
new file mode 100644
index 0000000..269fdd8
--- /dev/null
+++ b/hash_gnutls.c
@@ -0,0 +1,145 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Crypto hashing using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "hash.h"
+#include "logging.h"
+
+struct hash {
+  const HSH_Algorithm algorithm;
+  const gnutls_digest_algorithm_t type;
+  gnutls_hash_hd_t handle;
+};
+
+static struct hash hashes[] = {
+  { HSH_MD5_NONCRYPTO, GNUTLS_DIG_MD5, NULL },
+  { HSH_MD5, GNUTLS_DIG_MD5, NULL },
+  { HSH_SHA1, GNUTLS_DIG_SHA1, NULL },
+  { HSH_SHA256, GNUTLS_DIG_SHA256, NULL },
+  { HSH_SHA384, GNUTLS_DIG_SHA384, NULL },
+  { HSH_SHA512, GNUTLS_DIG_SHA512, NULL },
+  { HSH_SHA3_224, GNUTLS_DIG_SHA3_224, NULL },
+  { HSH_SHA3_256, GNUTLS_DIG_SHA3_256, NULL },
+  { HSH_SHA3_384, GNUTLS_DIG_SHA3_384, NULL },
+  { HSH_SHA3_512, GNUTLS_DIG_SHA3_512, NULL },
+  { 0, 0, NULL }
+};
+
+static int gnutls_initialised = 0;
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int id, r;
+
+  if (!gnutls_initialised) {
+    r = gnutls_global_init();
+    if (r < 0)
+      LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+    gnutls_initialised = 1;
+  }
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[id].algorithm == 0)
+    return -1;
+
+  if (hashes[id].handle)
+    return id;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_LAX_MODE();
+
+  r = gnutls_hash_init(&hashes[id].handle, hashes[id].type);
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_STRICT_MODE();
+
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "hash", gnutls_strerror(r));
+    hashes[id].handle = NULL;
+    return -1;
+  }
+
+  return id;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  gnutls_hash_hd_t handle;
+  int hash_len;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  handle = hashes[id].handle;
+  hash_len = gnutls_hash_get_len(hashes[id].type);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hash(handle, in1, in1_len) < 0 ||
+      (in2 && gnutls_hash(handle, in2, in2_len) < 0)) {
+    /* Reset the state */
+    gnutls_hash_output(handle, buf);
+    return 0;
+  }
+
+  gnutls_hash_output(handle, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  if (!gnutls_initialised)
+    return;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].handle)
+      gnutls_hash_deinit(hashes[i].handle, NULL);
+  }
+
+  gnutls_global_deinit();
+}
diff --git a/hash_intmd5.c b/hash_intmd5.c
new file mode 100644
index 0000000..a64b735
--- /dev/null
+++ b/hash_intmd5.c
@@ -0,0 +1,71 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using internal MD5 implementation.
+
+  */
+
+#include "config.h"
+#include "sysincl.h"
+#include "hash.h"
+#include "memory.h"
+#include "util.h"
+
+#include "md5.c"
+
+static MD5_CTX ctx;
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  /* only MD5 is supported */
+  if (algorithm != HSH_MD5 && algorithm != HSH_MD5_NONCRYPTO)
+    return -1;
+
+  return 0;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  MD5Init(&ctx);
+  MD5Update(&ctx, in1, in1_len);
+  if (in2)
+    MD5Update(&ctx, in2, in2_len);
+  MD5Final(&ctx);
+
+  out_len = MIN(out_len, 16);
+
+  memcpy(out, ctx.digest, out_len);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+}
diff --git a/hash_nettle.c b/hash_nettle.c
new file mode 100644
index 0000000..4a214f6
--- /dev/null
+++ b/hash_nettle.c
@@ -0,0 +1,124 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using the nettle library.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <nettle/nettle-meta.h>
+
+#include "hash.h"
+#include "memory.h"
+
+struct hash {
+  const HSH_Algorithm algorithm;
+  const char *int_name;
+  const struct nettle_hash *nettle_hash;
+  void *context;
+};
+
+static struct hash hashes[] = {
+  { HSH_MD5, "md5", NULL, NULL },
+  { HSH_SHA1, "sha1", NULL, NULL },
+  { HSH_SHA256, "sha256", NULL, NULL },
+  { HSH_SHA384, "sha384", NULL, NULL },
+  { HSH_SHA512, "sha512", NULL, NULL },
+  { HSH_SHA3_224, "sha3_224", NULL, NULL },
+  { HSH_SHA3_256, "sha3_256", NULL, NULL },
+  { HSH_SHA3_384, "sha3_384", NULL, NULL },
+  { HSH_SHA3_512, "sha3_512", NULL, NULL },
+  { 0, NULL, NULL, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int id, nid;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[id].algorithm == 0)
+    return -1;
+
+  if (hashes[id].context)
+    return id;
+
+  for (nid = 0; nettle_hashes[nid]; nid++) {
+    if (!strcmp(hashes[id].int_name, nettle_hashes[nid]->name))
+      break;
+  }
+
+  if (!nettle_hashes[nid] || !nettle_hashes[nid]->context_size || !nettle_hashes[nid]->init)
+    return -1;
+
+  hashes[id].nettle_hash = nettle_hashes[nid];
+  hashes[id].context = Malloc(hashes[id].nettle_hash->context_size);
+
+  return id;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  const struct nettle_hash *hash;
+  void *context;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  hash = hashes[id].nettle_hash;
+  context = hashes[id].context;
+
+  if (out_len > hash->digest_size)
+    out_len = hash->digest_size;
+
+  hash->init(context);
+  hash->update(context, in1_len, in1);
+  if (in2)
+    hash->update(context, in2_len, in2);
+  hash->digest(context, out_len, out);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].context)
+      Free(hashes[i].context);
+  }
+}
diff --git a/hash_nss.c b/hash_nss.c
new file mode 100644
index 0000000..4302447
--- /dev/null
+++ b/hash_nss.c
@@ -0,0 +1,114 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using NSSLOWHASH API of the NSS library.
+
+  */
+
+#include "config.h"
+
+#include <nss.h>
+#include <hasht.h>
+#include <nsslowhash.h>
+
+#include "hash.h"
+#include "util.h"
+
+static NSSLOWInitContext *ictx;
+
+struct hash {
+  HASH_HashType type;
+  HSH_Algorithm algorithm;
+  NSSLOWHASHContext *context;
+};
+
+static struct hash hashes[] = {
+  { HASH_AlgMD5, HSH_MD5, NULL },
+  { HASH_AlgSHA1, HSH_SHA1, NULL },
+  { HASH_AlgSHA256, HSH_SHA256, NULL },
+  { HASH_AlgSHA384, HSH_SHA384, NULL },
+  { HASH_AlgSHA512, HSH_SHA512, NULL },
+  { 0, 0, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int i;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[i].algorithm == 0)
+    return -1; /* not found */
+
+  if (!ictx && !(ictx = NSSLOW_Init()))
+    return -1; /* couldn't init NSS */
+
+  if (!hashes[i].context &&
+      !(hashes[i].context = NSSLOWHASH_NewContext(ictx, hashes[i].type)))
+    return -1; /* couldn't init hash */
+
+  return i;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  unsigned int ret = 0;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  NSSLOWHASH_Begin(hashes[id].context);
+  NSSLOWHASH_Update(hashes[id].context, in1, in1_len);
+  if (in2)
+    NSSLOWHASH_Update(hashes[id].context, in2, in2_len);
+  NSSLOWHASH_End(hashes[id].context, buf, &ret, sizeof (buf));
+
+  ret = MIN(ret, out_len);
+  memcpy(out, buf, ret);
+
+  return ret;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].context)
+      NSSLOWHASH_Destroy(hashes[i].context);
+  }
+
+  if (ictx)
+    NSSLOW_Shutdown(ictx);
+}
diff --git a/hash_tomcrypt.c b/hash_tomcrypt.c
new file mode 100644
index 0000000..9c425d2
--- /dev/null
+++ b/hash_tomcrypt.c
@@ -0,0 +1,126 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2012, 2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing crypto hashing using tomcrypt library.
+
+  */
+
+#include <tomcrypt.h>
+
+#include "config.h"
+#include "hash.h"
+#include "util.h"
+
+struct hash {
+  HSH_Algorithm algorithm;
+  const char *int_name;
+  const struct ltc_hash_descriptor *desc;
+};
+
+static const struct hash hashes[] = {
+  { HSH_MD5, "md5", &md5_desc },
+#ifdef LTC_SHA1
+  { HSH_SHA1, "sha1", &sha1_desc },
+#endif
+#ifdef LTC_SHA256
+  { HSH_SHA256, "sha256", &sha256_desc },
+#endif
+#ifdef LTC_SHA384
+  { HSH_SHA384, "sha384", &sha384_desc },
+#endif
+#ifdef LTC_SHA512
+  { HSH_SHA512, "sha512", &sha512_desc },
+#endif
+#ifdef LTC_SHA3
+  { HSH_SHA3_224, "sha3-224", &sha3_224_desc },
+  { HSH_SHA3_256, "sha3-256", &sha3_256_desc },
+  { HSH_SHA3_384, "sha3-384", &sha3_384_desc },
+  { HSH_SHA3_512, "sha3-512", &sha3_512_desc },
+#endif
+#ifdef LTC_TIGER
+  { HSH_TIGER, "tiger", &tiger_desc },
+#endif
+#ifdef LTC_WHIRLPOOL
+  { HSH_WHIRLPOOL, "whirlpool", &whirlpool_desc },
+#endif
+  { 0, NULL, NULL }
+};
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int i, h;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[i].algorithm == 0)
+    return -1; /* not found */
+
+  h = find_hash(hashes[i].int_name);
+  if (h >= 0)
+    return h; /* already registered */
+  
+  /* register and try again */
+  register_hash(hashes[i].desc);
+
+  return find_hash(hashes[i].int_name);
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  unsigned long len;
+  int r;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  len = sizeof (buf);
+  if (in2)
+    r = hash_memory_multi(id, buf, &len,
+                          in1, (unsigned long)in1_len,
+                          in2, (unsigned long)in2_len, NULL, 0);
+  else
+    r = hash_memory(id, in1, in1_len, buf, &len);
+
+  if (r != CRYPT_OK)
+    return 0;
+
+  len = MIN(len, out_len);
+  memcpy(out, buf, len);
+
+  return len;
+}
+
+void
+HSH_Finalise(void)
+{
+}
diff --git a/hwclock.c b/hwclock.c
new file mode 100644
index 0000000..86c7e51
--- /dev/null
+++ b/hwclock.c
@@ -0,0 +1,334 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Tracking of hardware clocks (e.g. RTC, PHC)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "regress.h"
+#include "util.h"
+
+/* Minimum and maximum number of samples per clock */
+#define MIN_SAMPLES 2
+#define MAX_SAMPLES 64
+
+/* Maximum acceptable frequency offset of the clock */
+#define MAX_FREQ_OFFSET (2.0 / 3.0)
+
+/* Quantiles for filtering readings by delay */
+#define DELAY_QUANT_MIN_K 1
+#define DELAY_QUANT_MAX_K 2
+#define DELAY_QUANT_Q 10
+#define DELAY_QUANT_REPEAT 7
+#define DELAY_QUANT_MIN_STEP 1.0e-9
+
+struct HCL_Instance_Record {
+  /* HW and local reference timestamp */
+  struct timespec hw_ref;
+  struct timespec local_ref;
+
+  /* Samples stored as intervals (uncorrected for frequency error)
+     relative to local_ref and hw_ref */
+  double *x_data;
+  double *y_data;
+
+  /* Minimum, maximum and current number of samples */
+  int min_samples;
+  int max_samples;
+  int n_samples;
+
+  /* Maximum error of the last sample */
+  double last_err;
+
+  /* Minimum interval between samples */
+  double min_separation;
+
+  /* Expected precision of readings */
+  double precision;
+
+  /* Flag indicating the offset and frequency values are valid */
+  int valid_coefs;
+
+  /* Estimated offset and frequency of HW clock relative to local clock */
+  double offset;
+  double frequency;
+
+  /* Estimated quantiles of reading delay */
+  QNT_Instance delay_quants;
+};
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  HCL_Instance clock;
+  double delta;
+
+  clock = anything;
+
+  if (clock->n_samples)
+    UTI_AdjustTimespec(&clock->local_ref, cooked, &clock->local_ref, &delta, dfreq, doffset);
+  if (clock->valid_coefs)
+    clock->frequency /= 1.0 - dfreq;
+}
+
+/* ================================================== */
+
+HCL_Instance
+HCL_CreateInstance(int min_samples, int max_samples, double min_separation, double precision)
+{
+  HCL_Instance clock;
+
+  min_samples = CLAMP(MIN_SAMPLES, min_samples, MAX_SAMPLES);
+  max_samples = CLAMP(MIN_SAMPLES, max_samples, MAX_SAMPLES);
+  max_samples = MAX(min_samples, max_samples);
+
+  clock = MallocNew(struct HCL_Instance_Record);
+  clock->x_data = MallocArray(double, max_samples);
+  clock->y_data = MallocArray(double, max_samples);
+  clock->x_data[max_samples - 1] = 0.0;
+  clock->y_data[max_samples - 1] = 0.0;
+  clock->min_samples = min_samples;
+  clock->max_samples = max_samples;
+  clock->n_samples = 0;
+  clock->valid_coefs = 0;
+  clock->min_separation = min_separation;
+  clock->precision = precision;
+  clock->delay_quants = QNT_CreateInstance(DELAY_QUANT_MIN_K, DELAY_QUANT_MAX_K,
+                                           DELAY_QUANT_Q, DELAY_QUANT_REPEAT,
+                                           DELAY_QUANT_MIN_STEP);
+
+  LCL_AddParameterChangeHandler(handle_slew, clock);
+
+  return clock;
+}
+
+/* ================================================== */
+
+void HCL_DestroyInstance(HCL_Instance clock)
+{
+  LCL_RemoveParameterChangeHandler(handle_slew, clock);
+  QNT_DestroyInstance(clock->delay_quants);
+  Free(clock->y_data);
+  Free(clock->x_data);
+  Free(clock);
+}
+
+/* ================================================== */
+
+int
+HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now)
+{
+  if (!clock->n_samples ||
+      fabs(UTI_DiffTimespecsToDouble(now, &clock->local_ref)) >= clock->min_separation)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                    struct timespec *hw_ts, struct timespec *local_ts, double *err)
+{
+  double delay, raw_delay, min_delay, low_delay, high_delay, e, pred_err;
+  double delay_sum, hw_sum, local_sum, local_prec, freq;
+  int i, min_reading, combined;
+  struct timespec ts1, ts2;
+
+  if (n_readings < 1)
+    return 0;
+
+  /* Work out the current correction multiplier needed to get cooked delays */
+  LCL_CookTime(&tss[0][0], &ts1, NULL);
+  LCL_CookTime(&tss[n_readings - 1][2], &ts2, NULL);
+  if (UTI_CompareTimespecs(&tss[0][0], &tss[n_readings - 1][2]) < 0)
+    freq = UTI_DiffTimespecsToDouble(&ts1, &ts2) /
+           UTI_DiffTimespecsToDouble(&tss[0][0], &tss[n_readings - 1][2]);
+  else
+    freq = 1.0;
+
+  for (i = 0; i < n_readings; i++) {
+    delay = freq * UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+
+    if (delay < 0.0) {
+      /* Step in the middle of a reading? */
+      DEBUG_LOG("Bad reading delay=%e", delay);
+      return 0;
+    }
+
+    if (i == 0 || min_delay > delay) {
+      min_delay = delay;
+      min_reading = i;
+    }
+
+    QNT_Accumulate(clock->delay_quants, delay);
+  }
+
+  local_prec = LCL_GetSysPrecisionAsQuantum();
+
+  low_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MIN_K);
+  high_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MAX_K);
+  low_delay = MIN(low_delay, high_delay);
+  high_delay = MAX(high_delay, low_delay + local_prec);
+
+  /* Combine readings with delay in the expected interval */
+  for (i = combined = 0, delay_sum = hw_sum = local_sum = 0.0; i < n_readings; i++) {
+    raw_delay = UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+    delay = freq * raw_delay;
+
+    if (delay < low_delay || delay > high_delay)
+      continue;
+
+    delay_sum += delay;
+    hw_sum += UTI_DiffTimespecsToDouble(&tss[i][1], &tss[0][1]);
+    local_sum += UTI_DiffTimespecsToDouble(&tss[i][0], &tss[0][0]) + raw_delay / 2.0;
+    combined++;
+  }
+
+  DEBUG_LOG("Combined %d readings lo=%e hi=%e", combined, low_delay, high_delay);
+
+  if (combined > 0) {
+    UTI_AddDoubleToTimespec(&tss[0][1], hw_sum / combined, hw_ts);
+    UTI_AddDoubleToTimespec(&tss[0][0], local_sum / combined, local_ts);
+    *err = MAX(delay_sum / combined / 2.0, clock->precision);
+    return 1;
+  }
+
+  /* Accept the reading with minimum delay if its interval does not contain
+     the current offset predicted from previous samples */
+
+  *hw_ts = tss[min_reading][1];
+  UTI_AddDoubleToTimespec(&tss[min_reading][0], min_delay / freq / 2.0, local_ts);
+  *err = MAX(min_delay / 2.0, clock->precision);
+
+  pred_err = 0.0;
+  LCL_CookTime(local_ts, &ts1, NULL);
+  if (!HCL_CookTime(clock, hw_ts, &ts2, &e) ||
+      ((pred_err = UTI_DiffTimespecsToDouble(&ts1, &ts2)) > *err)) {
+    DEBUG_LOG("Accepted reading err=%e prerr=%e", *err, pred_err);
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+void
+HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
+                     struct timespec *local_ts, double err)
+{
+  double hw_delta, local_delta, local_freq, raw_freq;
+  int i, n_runs, best_start;
+
+  local_freq = 1.0 - LCL_ReadAbsoluteFrequency() / 1.0e6;
+
+  /* Shift old samples */
+  if (clock->n_samples) {
+    if (clock->n_samples >= clock->max_samples)
+      clock->n_samples--;
+
+    hw_delta = UTI_DiffTimespecsToDouble(hw_ts, &clock->hw_ref);
+    local_delta = UTI_DiffTimespecsToDouble(local_ts, &clock->local_ref) / local_freq;
+
+    if (hw_delta <= 0.0 || local_delta < clock->min_separation / 2.0) {
+      clock->n_samples = 0;
+      DEBUG_LOG("HW clock reset interval=%f", local_delta);
+    }
+
+    for (i = clock->max_samples - clock->n_samples; i < clock->max_samples; i++) {
+      clock->y_data[i - 1] = clock->y_data[i] - hw_delta;
+      clock->x_data[i - 1] = clock->x_data[i] - local_delta;
+    }
+  }
+
+  clock->n_samples++;
+  clock->hw_ref = *hw_ts;
+  clock->local_ref = *local_ts;
+  clock->last_err = err;
+
+  /* Get new coefficients */
+  clock->valid_coefs =
+    RGR_FindBestRobustRegression(clock->x_data + clock->max_samples - clock->n_samples,
+                                 clock->y_data + clock->max_samples - clock->n_samples,
+                                 clock->n_samples, 1.0e-10, &clock->offset, &raw_freq,
+                                 &n_runs, &best_start);
+
+  if (!clock->valid_coefs) {
+    DEBUG_LOG("HW clock needs more samples");
+    return;
+  }
+
+  clock->frequency = raw_freq / local_freq;
+
+  /* Drop unneeded samples */
+  if (clock->n_samples > clock->min_samples)
+    clock->n_samples -= MIN(best_start, clock->n_samples - clock->min_samples);
+
+  /* If the fit doesn't cross the error interval of the last sample,
+     or the frequency is not sane, drop all samples and start again */
+  if (fabs(clock->offset) > err ||
+      fabs(clock->frequency - 1.0) > MAX_FREQ_OFFSET) {
+    DEBUG_LOG("HW clock reset");
+    clock->n_samples = 0;
+    clock->valid_coefs = 0;
+  }
+
+  DEBUG_LOG("HW clock samples=%d offset=%e freq=%e raw_freq=%e err=%e ref_diff=%e",
+            clock->n_samples, clock->offset, clock->frequency - 1.0, raw_freq - 1.0, err,
+            UTI_DiffTimespecsToDouble(&clock->hw_ref, &clock->local_ref));
+}
+
+/* ================================================== */
+
+int
+HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked, double *err)
+{
+  double offset, elapsed;
+
+  if (!clock->valid_coefs)
+    return 0;
+
+  elapsed = UTI_DiffTimespecsToDouble(raw, &clock->hw_ref);
+  offset = elapsed / clock->frequency - clock->offset;
+  UTI_AddDoubleToTimespec(&clock->local_ref, offset, cooked);
+
+  /* Fow now, just return the error of the last sample */
+  if (err)
+    *err = clock->last_err;
+
+  return 1;
+}
diff --git a/hwclock.h b/hwclock.h
new file mode 100644
index 0000000..c3415ad
--- /dev/null
+++ b/hwclock.h
@@ -0,0 +1,54 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for tracking of hardware clocks */
+
+#ifndef GOT_HWCLOCK_H
+#define GOT_HWCLOCK_H
+
+typedef struct HCL_Instance_Record *HCL_Instance;
+
+/* Create a new HW clock instance */
+extern HCL_Instance HCL_CreateInstance(int min_samples, int max_samples,
+                                       double min_separation, double precision);
+
+/* Destroy a HW clock instance */
+extern void HCL_DestroyInstance(HCL_Instance clock);
+
+/* Check if a new sample should be accumulated at this time */
+extern int HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now);
+
+/* Process new readings of the HW clock in form of (sys, hw, sys) triplets and
+   produce a sample which can be accumulated */
+extern int HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                               struct timespec *hw_ts, struct timespec *local_ts, double *err);
+
+/* Accumulate a new sample */
+extern void HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
+                                 struct timespec *local_ts, double err);
+
+/* Convert raw hardware time to cooked local time */
+extern int HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked,
+                        double *err);
+
+#endif
diff --git a/keys.c b/keys.c
new file mode 100644
index 0000000..9225e6c
--- /dev/null
+++ b/keys.c
@@ -0,0 +1,441 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2012-2016, 2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module for managing keys used for authenticating NTP packets and commands
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "keys.h"
+#include "cmac.h"
+#include "cmdparse.h"
+#include "conf.h"
+#include "memory.h"
+#include "util.h"
+#include "local.h"
+#include "logging.h"
+
+/* Consider 80 bits as the absolute minimum for a secure key */
+#define MIN_SECURE_KEY_LENGTH 10
+
+typedef enum {
+  NTP_MAC,
+  CMAC,
+} KeyClass;
+
+typedef struct {
+  uint32_t id;
+  int type;
+  int length;
+  KeyClass class;
+  union {
+    struct {
+      unsigned char *value;
+      int hash_id;
+    } ntp_mac;
+    CMC_Instance cmac;
+  } data;
+} Key;
+
+static ARR_Instance keys;
+
+static int cache_valid;
+static uint32_t cache_key_id;
+static int cache_key_pos;
+
+/* ================================================== */
+
+static void
+free_keys(void)
+{
+  unsigned int i;
+  Key *key;
+
+  for (i = 0; i < ARR_GetSize(keys); i++) {
+    key = ARR_GetElement(keys, i);
+    switch (key->class) {
+      case NTP_MAC:
+        Free(key->data.ntp_mac.value);
+        break;
+      case CMAC:
+        CMC_DestroyInstance(key->data.cmac);
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  ARR_SetSize(keys, 0);
+  cache_valid = 0;
+}
+
+/* ================================================== */
+
+void
+KEY_Initialise(void)
+{
+  keys = ARR_CreateInstance(sizeof (Key));
+  cache_valid = 0;
+  KEY_Reload();
+}
+
+/* ================================================== */
+
+void
+KEY_Finalise(void)
+{
+  free_keys();
+  ARR_DestroyInstance(keys);
+}
+
+/* ================================================== */
+
+static Key *
+get_key(unsigned int index)
+{
+  return ((Key *)ARR_GetElements(keys)) + index;
+}
+
+/* ================================================== */
+/* Decode key encoded in ASCII or HEX */
+
+static int
+decode_key(char *key)
+{
+  int len = strlen(key);
+
+  if (!strncmp(key, "ASCII:", 6)) {
+    memmove(key, key + 6, len - 6);
+    return len - 6;
+  } else if (!strncmp(key, "HEX:", 4)) {
+    return UTI_HexToBytes(key + 4, key, len);
+  } else {
+    /* assume ASCII */
+    return len;
+  }
+}
+
+/* ================================================== */
+
+/* Compare two keys */
+
+static int
+compare_keys_by_id(const void *a, const void *b)
+{
+  const Key *c = (const Key *) a;
+  const Key *d = (const Key *) b;
+
+  if (c->id < d->id) {
+    return -1;
+  } else if (c->id > d->id) {
+    return +1;
+  } else {
+    return 0;
+  }
+
+}
+
+/* ================================================== */
+
+void
+KEY_Reload(void)
+{
+  unsigned int i, line_number, key_length, cmac_key_length;
+  FILE *in;
+  char line[2048], *key_file, *key_value;
+  const char *key_type;
+  HSH_Algorithm hash_algorithm;
+  CMC_Algorithm cmac_algorithm;
+  int hash_id;
+  Key key;
+
+  free_keys();
+
+  key_file = CNF_GetKeysFile();
+  line_number = 0;
+
+  if (!key_file)
+    return;
+
+  if (!UTI_CheckFilePermissions(key_file, 0771))
+    ;
+
+  in = UTI_OpenFile(NULL, key_file, NULL, 'r', 0);
+  if (!in) {
+    LOG(LOGS_WARN, "Could not open keyfile %s", key_file);
+    return;
+  }
+
+  while (fgets(line, sizeof (line), in)) {
+    line_number++;
+
+    CPS_NormalizeLine(line);
+    if (!*line)
+      continue;
+
+    memset(&key, 0, sizeof (key));
+
+    if (!CPS_ParseKey(line, &key.id, &key_type, &key_value)) {
+      LOG(LOGS_WARN, "Could not parse key at line %u in file %s", line_number, key_file);
+      continue;
+    }
+
+    key_length = decode_key(key_value);
+    if (key_length == 0) {
+      LOG(LOGS_WARN, "Could not decode key %"PRIu32, key.id);
+      continue;
+    }
+
+    hash_algorithm = UTI_HashNameToAlgorithm(key_type);
+    cmac_algorithm = UTI_CmacNameToAlgorithm(key_type);
+
+    if (hash_algorithm != 0) {
+      hash_id = HSH_GetHashId(hash_algorithm);
+      if (hash_id < 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "hash function", key.id);
+        continue;
+      }
+      key.class = NTP_MAC;
+      key.type = hash_algorithm;
+      key.length = key_length;
+      key.data.ntp_mac.value = MallocArray(unsigned char, key_length);
+      memcpy(key.data.ntp_mac.value, key_value, key_length);
+      key.data.ntp_mac.hash_id = hash_id;
+    } else if (cmac_algorithm != 0) {
+      cmac_key_length = CMC_GetKeyLength(cmac_algorithm);
+      if (cmac_key_length == 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "cipher", key.id);
+        continue;
+      } else if (cmac_key_length != key_length) {
+        LOG(LOGS_WARN, "Invalid length of %s key %"PRIu32" (expected %u bits)",
+            key_type, key.id, 8 * cmac_key_length);
+        continue;
+      }
+
+      key.class = CMAC;
+      key.type = cmac_algorithm;
+      key.length = key_length;
+      key.data.cmac = CMC_CreateInstance(cmac_algorithm, (unsigned char *)key_value,
+                                         key_length);
+      assert(key.data.cmac);
+    } else {
+      LOG(LOGS_WARN, "Invalid type in key %"PRIu32, key.id);
+      continue;
+    }
+
+    ARR_AppendElement(keys, &key);
+  }
+
+  fclose(in);
+
+  /* Sort keys into order.  Note, if there's a duplicate, it is
+     arbitrary which one we use later - the user should have been
+     more careful! */
+  qsort(ARR_GetElements(keys), ARR_GetSize(keys), sizeof (Key), compare_keys_by_id);
+
+  LOG(LOGS_INFO, "Loaded %u symmetric keys", ARR_GetSize(keys));
+
+  /* Check for duplicates */
+  for (i = 1; i < ARR_GetSize(keys); i++) {
+    if (get_key(i - 1)->id == get_key(i)->id)
+      LOG(LOGS_WARN, "Detected duplicate key %"PRIu32, get_key(i - 1)->id);
+  }
+
+  /* Erase any passwords from stack */
+  memset(line, 0, sizeof (line));
+}
+
+/* ================================================== */
+
+static int
+lookup_key(uint32_t id)
+{
+  Key specimen, *where, *keys_ptr;
+  int pos;
+
+  keys_ptr = ARR_GetElements(keys);
+  specimen.id = id;
+  where = (Key *)bsearch((void *)&specimen, keys_ptr, ARR_GetSize(keys),
+                         sizeof (Key), compare_keys_by_id);
+  if (!where) {
+    return -1;
+  } else {
+    pos = where - keys_ptr;
+    return pos;
+  }
+}
+
+/* ================================================== */
+
+static Key *
+get_key_by_id(uint32_t key_id)
+{
+  int position;
+
+  if (cache_valid && key_id == cache_key_id)
+    return get_key(cache_key_pos);
+
+  position = lookup_key(key_id);
+
+  if (position >= 0) {
+    cache_valid = 1;
+    cache_key_pos = position;
+    cache_key_id = key_id;
+
+    return get_key(position);
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+KEY_KeyKnown(uint32_t key_id)
+{
+  return get_key_by_id(key_id) != NULL;
+}
+
+/* ================================================== */
+
+int
+KEY_GetAuthLength(uint32_t key_id)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  switch (key->class) {
+    case NTP_MAC:
+      return HSH_Hash(key->data.ntp_mac.hash_id, buf, 0, buf, 0, buf, sizeof (buf));
+    case CMAC:
+      return CMC_Hash(key->data.cmac, buf, 0, buf, sizeof (buf));
+    default:
+      assert(0);
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+KEY_CheckKeyLength(uint32_t key_id)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return key->length >= MIN_SECURE_KEY_LENGTH;
+}
+
+/* ================================================== */
+
+int
+KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  *type = key->type;
+  *bits = 8 * key->length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+generate_auth(Key *key, const void *data, int data_len, unsigned char *auth, int auth_len)
+{
+  switch (key->class) {
+    case NTP_MAC:
+      return HSH_Hash(key->data.ntp_mac.hash_id, key->data.ntp_mac.value,
+                      key->length, data, data_len, auth, auth_len);
+    case CMAC:
+      return CMC_Hash(key->data.cmac, data, data_len, auth, auth_len);
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static int
+check_auth(Key *key, const void *data, int data_len,
+           const unsigned char *auth, int auth_len, int trunc_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  int hash_len;
+
+  hash_len = generate_auth(key, data, data_len, buf, sizeof (buf));
+
+  return MIN(hash_len, trunc_len) == auth_len && !memcmp(buf, auth, auth_len);
+}
+
+/* ================================================== */
+
+int
+KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
+                 unsigned char *auth, int auth_len)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return generate_auth(key, data, data_len, auth, auth_len);
+}
+
+/* ================================================== */
+
+int
+KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
+              const unsigned char *auth, int auth_len, int trunc_len)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  return check_auth(key, data, data_len, auth, auth_len, trunc_len);
+}
diff --git a/keys.h b/keys.h
new file mode 100644
index 0000000..c89fea9
--- /dev/null
+++ b/keys.h
@@ -0,0 +1,47 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for key management module
+  */
+
+#ifndef GOT_KEYS_H
+#define GOT_KEYS_H
+
+#include "sysincl.h"
+
+extern void KEY_Initialise(void);
+extern void KEY_Finalise(void);
+
+extern void KEY_Reload(void);
+
+extern int KEY_KeyKnown(uint32_t key_id);
+extern int KEY_GetAuthLength(uint32_t key_id);
+extern int KEY_CheckKeyLength(uint32_t key_id);
+extern int KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits);
+
+extern int KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
+                            unsigned char *auth, int auth_len);
+extern int KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
+                         const unsigned char *auth, int auth_len, int trunc_len);
+
+#endif /* GOT_KEYS_H */
diff --git a/local.c b/local.c
new file mode 100644
index 0000000..b32d0c6
--- /dev/null
+++ b/local.c
@@ -0,0 +1,781 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2014-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The routines in this file present a common local (system) clock
+  interface to the rest of the software.
+
+  They interface with the system specific driver files in sys_*.c
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "memory.h"
+#include "smooth.h"
+#include "util.h"
+#include "logging.h"
+
+/* ================================================== */
+
+/* Variable to store the current frequency, in ppm */
+static double current_freq_ppm;
+
+/* Maximum allowed frequency, in ppm */
+static double max_freq_ppm;
+
+/* Temperature compensation, in ppm */
+static double temp_comp_ppm;
+
+/* ================================================== */
+/* Store the system dependent drivers */
+
+static lcl_ReadFrequencyDriver drv_read_freq;
+static lcl_SetFrequencyDriver drv_set_freq;
+static lcl_AccrueOffsetDriver drv_accrue_offset;
+static lcl_ApplyStepOffsetDriver drv_apply_step_offset;
+static lcl_OffsetCorrectionDriver drv_offset_convert;
+static lcl_SetLeapDriver drv_set_leap;
+static lcl_SetSyncStatusDriver drv_set_sync_status;
+
+/* ================================================== */
+
+/* Types and variables associated with handling the parameter change
+   list */
+
+typedef struct _ChangeListEntry {
+  struct _ChangeListEntry *next;
+  struct _ChangeListEntry *prev;
+  LCL_ParameterChangeHandler handler;
+  void *anything;
+} ChangeListEntry;
+
+static ChangeListEntry change_list;
+
+/* ================================================== */
+
+/* Types and variables associated with handling the parameter change
+   list */
+
+typedef struct _DispersionNotifyListEntry {
+  struct _DispersionNotifyListEntry *next;
+  struct _DispersionNotifyListEntry *prev;
+  LCL_DispersionNotifyHandler handler;
+  void *anything;
+} DispersionNotifyListEntry;
+
+static DispersionNotifyListEntry dispersion_notify_list;
+
+/* ================================================== */
+
+static int precision_log;
+static double precision_quantum;
+
+static double max_clock_error;
+
+/* ================================================== */
+
+/* Define the number of increments of the system clock that we want
+   to see to be fairly sure that we've got something approaching
+   the minimum increment.  Even on a crummy implementation that can't
+   interpolate between 10ms ticks, we should get this done in
+   under 1s of busy waiting. */
+#define NITERS 100
+
+#define NSEC_PER_SEC 1000000000
+
+static double
+measure_clock_precision(void)
+{
+  struct timespec ts, old_ts;
+  int iters, diff, best;
+
+  LCL_ReadRawTime(&old_ts);
+
+  /* Assume we must be better than a second */
+  best = NSEC_PER_SEC;
+  iters = 0;
+
+  do {
+    LCL_ReadRawTime(&ts);
+
+    diff = NSEC_PER_SEC * (ts.tv_sec - old_ts.tv_sec) + (ts.tv_nsec - old_ts.tv_nsec);
+
+    old_ts = ts;
+    if (diff > 0) {
+      if (diff < best)
+        best = diff;
+      iters++;
+    }
+  } while (iters < NITERS);
+
+  assert(best > 0);
+
+  return 1.0e-9 * best;
+}
+
+/* ================================================== */
+
+void
+LCL_Initialise(void)
+{
+  change_list.next = change_list.prev = &change_list;
+
+  dispersion_notify_list.next = dispersion_notify_list.prev = &dispersion_notify_list;
+
+  /* Null out the system drivers, so that we die
+     if they never get defined before use */
+  
+  drv_read_freq = NULL;
+  drv_set_freq = NULL;
+  drv_accrue_offset = NULL;
+  drv_offset_convert = NULL;
+
+  /* This ought to be set from the system driver layer */
+  current_freq_ppm = 0.0;
+  temp_comp_ppm = 0.0;
+
+  precision_quantum = CNF_GetClockPrecision();
+  if (precision_quantum <= 0.0)
+    precision_quantum = measure_clock_precision();
+
+  precision_quantum = CLAMP(1.0e-9, precision_quantum, 1.0);
+  precision_log = round(log(precision_quantum) / log(2.0));
+  /* NTP code doesn't support smaller log than -30 */
+  assert(precision_log >= -30);
+
+  DEBUG_LOG("Clock precision %.9f (%d)", precision_quantum, precision_log);
+
+  /* This is the maximum allowed frequency offset in ppm, the time must
+     never stop or run backwards */
+  max_freq_ppm = CNF_GetMaxDrift();
+  max_freq_ppm = CLAMP(0.0, max_freq_ppm, 500000.0);
+
+  max_clock_error = CNF_GetMaxClockError() * 1e-6;
+}
+
+/* ================================================== */
+
+void
+LCL_Finalise(void)
+{
+  /* Make sure all handlers have been removed */
+  if (change_list.next != &change_list)
+    assert(0);
+  if (dispersion_notify_list.next != &dispersion_notify_list)
+    assert(0);
+}
+
+/* ================================================== */
+
+/* Routine to read the system precision as a log to base 2 value. */
+int
+LCL_GetSysPrecisionAsLog(void)
+{
+  return precision_log;
+}
+
+/* ================================================== */
+/* Routine to read the system precision in terms of the actual time step */
+
+double
+LCL_GetSysPrecisionAsQuantum(void)
+{
+  return precision_quantum;
+}
+
+/* ================================================== */
+
+double
+LCL_GetMaxClockError(void)
+{
+  return max_clock_error;
+}
+
+/* ================================================== */
+
+void
+LCL_AddParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything)
+{
+  ChangeListEntry *ptr, *new_entry;
+
+  /* Check that the handler is not already registered */
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    if (!(ptr->handler != handler || ptr->anything != anything)) {
+      assert(0);
+    }
+  }
+
+  new_entry = MallocNew(ChangeListEntry);
+
+  new_entry->handler = handler;
+  new_entry->anything = anything;
+
+  /* Chain it into the list */
+  new_entry->next = &change_list;
+  new_entry->prev = change_list.prev;
+  change_list.prev->next = new_entry;
+  change_list.prev = new_entry;
+}
+
+/* ================================================== */
+
+/* Remove a handler */
+void LCL_RemoveParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything)
+{
+
+  ChangeListEntry *ptr;
+  int ok;
+
+  ptr = NULL;
+  ok = 0;
+
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    if (ptr->handler == handler && ptr->anything == anything) {
+      ok = 1;
+      break;
+    }
+  }
+
+  assert(ok);
+
+  /* Unlink entry from the list */
+  ptr->next->prev = ptr->prev;
+  ptr->prev->next = ptr->next;
+
+  Free(ptr);
+}
+
+/* ================================================== */
+
+int
+LCL_IsFirstParameterChangeHandler(LCL_ParameterChangeHandler handler)
+{
+  return change_list.next->handler == handler;
+}
+
+/* ================================================== */
+
+static void
+invoke_parameter_change_handlers(struct timespec *raw, struct timespec *cooked,
+                                 double dfreq, double doffset,
+                                 LCL_ChangeType change_type)
+{
+  ChangeListEntry *ptr;
+
+  for (ptr = change_list.next; ptr != &change_list; ptr = ptr->next) {
+    (ptr->handler)(raw, cooked, dfreq, doffset, change_type, ptr->anything);
+  }
+}
+
+/* ================================================== */
+
+void
+LCL_AddDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything)
+{
+  DispersionNotifyListEntry *ptr, *new_entry;
+
+  /* Check that the handler is not already registered */
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    if (!(ptr->handler != handler || ptr->anything != anything)) {
+      assert(0);
+    }
+  }
+
+  new_entry = MallocNew(DispersionNotifyListEntry);
+
+  new_entry->handler = handler;
+  new_entry->anything = anything;
+
+  /* Chain it into the list */
+  new_entry->next = &dispersion_notify_list;
+  new_entry->prev = dispersion_notify_list.prev;
+  dispersion_notify_list.prev->next = new_entry;
+  dispersion_notify_list.prev = new_entry;
+}
+
+/* ================================================== */
+
+/* Remove a handler */
+extern 
+void LCL_RemoveDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything)
+{
+
+  DispersionNotifyListEntry *ptr;
+  int ok;
+
+  ptr = NULL;
+  ok = 0;
+
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    if (ptr->handler == handler && ptr->anything == anything) {
+      ok = 1;
+      break;
+    }
+  }
+
+  assert(ok);
+
+  /* Unlink entry from the list */
+  ptr->next->prev = ptr->prev;
+  ptr->prev->next = ptr->next;
+
+  Free(ptr);
+}
+
+/* ================================================== */
+
+void
+LCL_ReadRawTime(struct timespec *ts)
+{
+#if HAVE_CLOCK_GETTIME
+  if (clock_gettime(CLOCK_REALTIME, ts) < 0)
+    LOG_FATAL("clock_gettime() failed : %s", strerror(errno));
+#else
+  struct timeval tv;
+
+  if (gettimeofday(&tv, NULL) < 0)
+    LOG_FATAL("gettimeofday() failed : %s", strerror(errno));
+
+  UTI_TimevalToTimespec(&tv, ts);
+#endif
+}
+
+/* ================================================== */
+
+void
+LCL_ReadCookedTime(struct timespec *result, double *err)
+{
+  struct timespec raw;
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, result, err);
+}
+
+/* ================================================== */
+
+void
+LCL_CookTime(struct timespec *raw, struct timespec *cooked, double *err)
+{
+  double correction;
+
+  LCL_GetOffsetCorrection(raw, &correction, err);
+  UTI_AddDoubleToTimespec(raw, correction, cooked);
+}
+
+/* ================================================== */
+
+void
+LCL_GetOffsetCorrection(struct timespec *raw, double *correction, double *err)
+{
+  /* Call system specific driver to get correction */
+  (*drv_offset_convert)(raw, correction, err);
+}
+
+/* ================================================== */
+/* Return current frequency */
+
+double
+LCL_ReadAbsoluteFrequency(void)
+{
+  double freq;
+
+  freq = current_freq_ppm; 
+
+  /* Undo temperature compensation */
+  if (temp_comp_ppm != 0.0) {
+    freq = (freq + temp_comp_ppm) / (1.0 - 1.0e-6 * temp_comp_ppm);
+  }
+
+  return freq;
+}
+
+/* ================================================== */
+
+static double
+clamp_freq(double freq)
+{
+  if (freq <= max_freq_ppm && freq >= -max_freq_ppm)
+    return freq;
+
+  LOG(LOGS_WARN, "Frequency %.1f ppm exceeds allowed maximum", freq);
+
+  return CLAMP(-max_freq_ppm, freq, max_freq_ppm);
+}
+
+/* ================================================== */
+
+static int
+check_offset(struct timespec *now, double offset)
+{
+  /* Check if the time will be still sane with accumulated offset */
+  if (UTI_IsTimeOffsetSane(now, -offset))
+      return 1;
+
+  LOG(LOGS_WARN, "Adjustment of %.1f seconds is invalid", -offset);
+  return 0;
+}
+
+/* ================================================== */
+
+/* This involves both setting the absolute frequency with the
+   system-specific driver, as well as calling all notify handlers */
+
+void
+LCL_SetAbsoluteFrequency(double afreq_ppm)
+{
+  struct timespec raw, cooked;
+  double dfreq;
+  
+  afreq_ppm = clamp_freq(afreq_ppm);
+
+  /* Apply temperature compensation */
+  if (temp_comp_ppm != 0.0) {
+    afreq_ppm = afreq_ppm * (1.0 - 1.0e-6 * temp_comp_ppm) - temp_comp_ppm;
+  }
+
+  /* Call the system-specific driver for setting the frequency */
+  
+  afreq_ppm = (*drv_set_freq)(afreq_ppm);
+
+  dfreq = (afreq_ppm - current_freq_ppm) / (1.0e6 - current_freq_ppm);
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, 0.0, LCL_ChangeAdjust);
+
+  current_freq_ppm = afreq_ppm;
+
+}
+
+/* ================================================== */
+
+void
+LCL_AccumulateDeltaFrequency(double dfreq)
+{
+  struct timespec raw, cooked;
+  double old_freq_ppm;
+
+  old_freq_ppm = current_freq_ppm;
+
+  /* Work out new absolute frequency.  Note that absolute frequencies
+   are handled in units of ppm, whereas the 'dfreq' argument is in
+   terms of the gradient of the (offset) v (local time) function. */
+
+  current_freq_ppm += dfreq * (1.0e6 - current_freq_ppm);
+
+  current_freq_ppm = clamp_freq(current_freq_ppm);
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, 0.0, LCL_ChangeAdjust);
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateOffset(double offset, double corr_rate)
+{
+  struct timespec raw, cooked;
+
+  /* In this case, the cooked time to be passed to the notify clients
+     has to be the cooked time BEFORE the change was made */
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&cooked, offset))
+    return 0;
+
+  (*drv_accrue_offset)(offset, corr_rate);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, offset, LCL_ChangeAdjust);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+LCL_ApplyStepOffset(double offset)
+{
+  struct timespec raw, cooked;
+
+  /* In this case, the cooked time to be passed to the notify clients
+     has to be the cooked time BEFORE the change was made */
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&raw, offset))
+      return 0;
+
+  if (!(*drv_apply_step_offset)(offset)) {
+    LOG(LOGS_ERR, "Could not step system clock");
+    return 0;
+  }
+
+  /* Reset smoothing on all clock steps */
+  SMT_Reset(&cooked);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, offset, LCL_ChangeStep);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
+    double offset, double dispersion)
+{
+  LCL_CancelOffsetCorrection();
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(raw, cooked, 0.0, offset, LCL_ChangeUnknownStep);
+
+  lcl_InvokeDispersionNotifyHandlers(dispersion);
+}
+
+/* ================================================== */
+
+void
+LCL_NotifyLeap(int leap)
+{
+  struct timespec raw, cooked;
+
+  LCL_ReadRawTime(&raw);
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  /* Smooth the leap second out */
+  SMT_Leap(&cooked, leap);
+
+  /* Dispatch to all handlers as if the clock was stepped */
+  invoke_parameter_change_handlers(&raw, &cooked, 0.0, -leap, LCL_ChangeStep);
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)
+{
+  struct timespec raw, cooked;
+  double old_freq_ppm;
+
+  LCL_ReadRawTime(&raw);
+  /* Due to modifying the offset, this has to be the cooked time prior
+     to the change we are about to make */
+  LCL_CookTime(&raw, &cooked, NULL);
+
+  if (!check_offset(&cooked, doffset))
+    return 0;
+
+  old_freq_ppm = current_freq_ppm;
+
+  /* Work out new absolute frequency.  Note that absolute frequencies
+   are handled in units of ppm, whereas the 'dfreq' argument is in
+   terms of the gradient of the (offset) v (local time) function. */
+  current_freq_ppm += dfreq * (1.0e6 - current_freq_ppm);
+
+  current_freq_ppm = clamp_freq(current_freq_ppm);
+
+  DEBUG_LOG("old_freq=%.3fppm new_freq=%.3fppm offset=%.6fsec",
+      old_freq_ppm, current_freq_ppm, doffset);
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+  dfreq = (current_freq_ppm - old_freq_ppm) / (1.0e6 - old_freq_ppm);
+
+  (*drv_accrue_offset)(doffset, corr_rate);
+
+  /* Dispatch to all handlers */
+  invoke_parameter_change_handlers(&raw, &cooked, dfreq, doffset, LCL_ChangeAdjust);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset, double corr_rate)
+{
+  ChangeListEntry *first_handler;
+  int r;
+
+  first_handler = change_list.next;
+  change_list.next = &change_list;
+
+  r = LCL_AccumulateFrequencyAndOffset(dfreq, doffset, corr_rate);
+
+  change_list.next = first_handler;
+
+  return r;
+}
+
+/* ================================================== */
+
+void
+lcl_InvokeDispersionNotifyHandlers(double dispersion)
+{
+  DispersionNotifyListEntry *ptr;
+
+  for (ptr = dispersion_notify_list.next; ptr != &dispersion_notify_list; ptr = ptr->next) {
+    (ptr->handler)(dispersion, ptr->anything);
+  }
+
+}
+
+/* ================================================== */
+
+void
+lcl_RegisterSystemDrivers(lcl_ReadFrequencyDriver read_freq,
+                          lcl_SetFrequencyDriver set_freq,
+                          lcl_AccrueOffsetDriver accrue_offset,
+                          lcl_ApplyStepOffsetDriver apply_step_offset,
+                          lcl_OffsetCorrectionDriver offset_convert,
+                          lcl_SetLeapDriver set_leap,
+                          lcl_SetSyncStatusDriver set_sync_status)
+{
+  drv_read_freq = read_freq;
+  drv_set_freq = set_freq;
+  drv_accrue_offset = accrue_offset;
+  drv_apply_step_offset = apply_step_offset;
+  drv_offset_convert = offset_convert;
+  drv_set_leap = set_leap;
+  drv_set_sync_status = set_sync_status;
+
+  current_freq_ppm = (*drv_read_freq)();
+
+  DEBUG_LOG("Local freq=%.3fppm", current_freq_ppm);
+}
+
+/* ================================================== */
+/* Look at the current difference between the system time and the NTP
+   time, and make a step to cancel it. */
+
+int
+LCL_MakeStep(void)
+{
+  struct timespec raw;
+  double correction;
+
+  LCL_ReadRawTime(&raw);
+  LCL_GetOffsetCorrection(&raw, &correction, NULL);
+
+  if (!check_offset(&raw, -correction))
+      return 0;
+
+  /* Cancel remaining slew and make the step */
+  LCL_AccumulateOffset(correction, 0.0);
+  if (!LCL_ApplyStepOffset(-correction))
+    return 0;
+
+  LOG(LOGS_WARN, "System clock was stepped by %.6f seconds", correction);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+LCL_CancelOffsetCorrection(void)
+{
+  struct timespec raw;
+  double correction;
+
+  LCL_ReadRawTime(&raw);
+  LCL_GetOffsetCorrection(&raw, &correction, NULL);
+  LCL_AccumulateOffset(correction, 0.0);
+}
+
+/* ================================================== */
+
+int
+LCL_CanSystemLeap(void)
+{
+  return drv_set_leap ? 1 : 0;
+}
+
+/* ================================================== */
+
+void
+LCL_SetSystemLeap(int leap, int tai_offset)
+{
+  if (drv_set_leap) {
+    (drv_set_leap)(leap, tai_offset);
+  }
+}
+
+/* ================================================== */
+
+double
+LCL_SetTempComp(double comp)
+{
+  double uncomp_freq_ppm;
+
+  if (temp_comp_ppm == comp)
+    return comp;
+
+  /* Undo previous compensation */
+  current_freq_ppm = (current_freq_ppm + temp_comp_ppm) /
+    (1.0 - 1.0e-6 * temp_comp_ppm);
+
+  uncomp_freq_ppm = current_freq_ppm;
+
+  /* Apply new compensation */
+  current_freq_ppm = current_freq_ppm * (1.0 - 1.0e-6 * comp) - comp;
+
+  /* Call the system-specific driver for setting the frequency */
+  current_freq_ppm = (*drv_set_freq)(current_freq_ppm);
+
+  temp_comp_ppm = (uncomp_freq_ppm - current_freq_ppm) /
+    (1.0e-6 * uncomp_freq_ppm + 1.0);
+
+  return temp_comp_ppm;
+}
+
+/* ================================================== */
+
+void
+LCL_SetSyncStatus(int synchronised, double est_error, double max_error)
+{
+  if (drv_set_sync_status) {
+    (drv_set_sync_status)(synchronised, est_error, max_error);
+  }
+}
+
+/* ================================================== */
diff --git a/local.h b/local.h
new file mode 100644
index 0000000..a23d275
--- /dev/null
+++ b/local.h
@@ -0,0 +1,229 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module provides an interface to the system time, and
+  insulates the rest of the program from the different way
+  that interface has to be done on various operating systems.
+  */
+
+#ifndef GOT_LOCAL_H
+#define GOT_LOCAL_H
+
+#include "sysincl.h"
+
+/* Read the system clock */
+extern void LCL_ReadRawTime(struct timespec *ts);
+
+/* Read the system clock, corrected according to all accumulated
+   drifts and uncompensated offsets.
+
+   In a kernel implementation with vernier frequency control (like
+   Linux), and if we were to apply offsets by stepping the clock, this
+   would be identical to raw time.  In any other case (use of
+   adjtime()-like interface to correct offsets, and to adjust the
+   frequency), we must correct the raw time to get this value */
+
+extern void LCL_ReadCookedTime(struct timespec *ts, double *err);
+
+/* Convert raw time to cooked. */
+extern void LCL_CookTime(struct timespec *raw, struct timespec *cooked, double *err);
+
+/* Read the current offset between the system clock and true time
+   (i.e. 'cooked' - 'raw') (in seconds). */
+
+extern void LCL_GetOffsetCorrection(struct timespec *raw, double *correction, double *err);
+
+/* Type of routines that may be invoked as callbacks when there is a
+   change to the frequency or offset.
+
+   raw : raw local clock time at which change occurred
+
+   cooked : cooked local time at which change occurred
+
+   dfreq : delta frequency relative to previous value (in terms of
+   seconds gained by system clock per unit system clock time)
+
+   doffset : delta offset applied (positive => make local system fast
+   by that amount, negative => make it slow by that amount)
+
+   change_type : what type of change is being applied
+   
+   anything : Passthrough argument from call to registration routine */
+
+
+typedef enum {
+  LCL_ChangeAdjust,
+  LCL_ChangeStep,
+  LCL_ChangeUnknownStep
+} LCL_ChangeType;
+
+typedef void (*LCL_ParameterChangeHandler)
+     (struct timespec *raw, struct timespec *cooked,
+      double dfreq,
+      double doffset,
+      LCL_ChangeType change_type,
+      void *anything
+      );
+
+/* Add a handler.  Then handler MUST NOT deregister itself!!! */
+extern void LCL_AddParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything);
+
+/* Remove a handler */
+extern void LCL_RemoveParameterChangeHandler(LCL_ParameterChangeHandler, void *anything);
+
+/* Check if a handler is invoked first when dispatching */
+extern int LCL_IsFirstParameterChangeHandler(LCL_ParameterChangeHandler handler);
+
+/* Function type for handlers to be called back when an indeterminate
+   offset is introduced into the local time.  This situation occurs
+   when the frequency must be adjusted to effect a clock slew and
+   there is doubt about one of the endpoints of the interval over
+   which the frequency change was applied.It is expected that such
+   handlers will add extra dispersion to any existing samples stored
+   in their registers. 
+
+   dispersion : The bound on how much error has been introduced in the
+   local clock, in seconds.
+
+   anything : passthrough from the registration routine
+
+   */
+
+typedef void (*LCL_DispersionNotifyHandler)(double dispersion, void *anything);
+
+/* Register a handler for being notified of dispersion being added to
+   the local clock.  The handler MUST NOT unregister itself!!! */
+
+extern void LCL_AddDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
+
+/* Delete a handler */
+
+extern void LCL_RemoveDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
+
+
+/* Read the absolute system frequency, relative to the uncompensated
+   system.  Returned in units of parts per million.  Thus the result of
+   this is how many seconds fast the uncompensated system would be after
+   its own time has reached 1 million seconds from the start of the
+   measurement.  */
+extern double LCL_ReadAbsoluteFrequency(void);
+
+/* Routine to set the absolute frequency.  Only expected to be used
+   when either (i) reading the drift from a file at the start of a
+   run, or (ii) responsing to a user parameter 'poke'.  This is
+   defined in ppm, as for the absolute frequency reading routine. */
+
+extern void LCL_SetAbsoluteFrequency(double afreq);
+
+/* Routine to apply a change of frequency to the local clock.  The
+   argument is the estimated gain (positive) or loss (negative) of the
+   local clock relative to true time, per unit time of the PREVIOUS
+   frequency setting of the local clock.  This is assumed to be based
+   on a regression of y=offset v x=cooked local time. */
+
+extern void LCL_AccumulateDeltaFrequency(double dfreq);
+
+/* Routine to apply an offset (in seconds) to the local clock.  The
+   argument should be positive to move the clock backwards (i.e. the
+   local clock is currently fast of true time), or negative to move it
+   forwards (i.e. it is currently slow of true time).  Provided is also
+   a suggested correction rate (correction time * offset). */
+
+extern int LCL_AccumulateOffset(double offset, double corr_rate);
+
+/* Routine to apply an immediate offset by doing a sudden step if
+   possible. (Intended for use after an initial estimate of offset has
+   been obtained, so that we don't end up using adjtime to achieve a
+   slew of an hour or something like that). A positive argument means
+   the system clock is fast on true time, i.e. it needs to be stepped
+   backwards. (Same convention as for AccumulateOffset routine). */
+
+extern int LCL_ApplyStepOffset(double offset);
+
+/* Routine to invoke notify handlers on an unexpected time jump
+   in system clock */
+extern void LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
+    double offset, double dispersion);
+
+/* Routine to invoke notify handlers on leap second when the system clock
+   doesn't correct itself */
+extern void LCL_NotifyLeap(int leap);
+
+/* Perform the combination of modifying the frequency and applying
+   a slew, in one easy step */
+extern int LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate);
+
+/* Same as the routine above, except it does not call the registered
+   parameter change handlers */
+extern int LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset,
+                                                      double corr_rate);
+
+/* Routine to read the system precision as a log to base 2 value. */
+extern int LCL_GetSysPrecisionAsLog(void);
+
+/* Routine to read the system precision in terms of the actual time step */
+extern double LCL_GetSysPrecisionAsQuantum(void);
+
+/* Routine to read the maximum frequency error of the local clock.  This
+   is a frequency stability, not an absolute error. */
+extern double LCL_GetMaxClockError(void);
+
+/* Routine to initialise the module (to be called once at program
+   start-up) */
+
+extern void LCL_Initialise(void);
+
+/* Routine to finalise the module (to be called once at end of
+   run). */
+extern void LCL_Finalise(void);
+
+/* Routine to convert the outstanding system clock error to a step and
+   apply it, e.g. if the system clock has ended up an hour wrong due
+   to a timezone problem. */
+extern int LCL_MakeStep(void);
+
+/* Routine to cancel the outstanding system clock correction */
+extern void LCL_CancelOffsetCorrection(void);
+
+/* Check if the system driver supports leap seconds, i.e. LCL_SetSystemLeap
+   does something */
+extern int LCL_CanSystemLeap(void);
+
+/* Routine to set the system clock to correct itself for a leap second and also
+   set its TAI-UTC offset.  If supported, leap second will be inserted at the
+   end of the day if the argument is positive, deleted if negative, and zero
+   resets the setting. */
+extern void LCL_SetSystemLeap(int leap, int tai_offset);
+
+/* Routine to set a frequency correction (in ppm) that should be applied
+   to local clock to compensate for temperature changes.  A positive
+   argument means that the clock frequency should be increased. Return the
+   actual compensation (may be different from the requested compensation
+   due to clamping or rounding). */
+extern double LCL_SetTempComp(double comp);
+
+/* Routine to update the synchronisation status in the kernel to allow other
+   applications to know if the system clock is synchronised and error bounds */
+extern void LCL_SetSyncStatus(int synchronised, double est_error, double max_error);
+
+#endif /* GOT_LOCAL_H */
diff --git a/localp.h b/localp.h
new file mode 100644
index 0000000..6f65e43
--- /dev/null
+++ b/localp.h
@@ -0,0 +1,74 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Private include file for local.c and all system dependent
+  driver modules.
+  */
+
+
+#ifndef GOT_LOCALP_H
+#define GOT_LOCALP_H
+
+/* System driver to read the current local frequency, in ppm relative
+   to nominal.  A positive value indicates that the local clock runs
+   fast when uncompensated. */
+typedef double (*lcl_ReadFrequencyDriver)(void);
+
+/* System driver to set the current local frequency, in ppm relative
+   to nominal.  A positive value indicates that the local clock runs
+   fast when uncompensated.  Return actual frequency (may be different
+   from the requested frequency due to clamping or rounding). */
+typedef double (*lcl_SetFrequencyDriver)(double freq_ppm);
+
+/* System driver to accrue an offset. A positive argument means slew
+   the clock forwards.  The suggested correction rate of time to correct the
+   offset is given in 'corr_rate'. */
+typedef void (*lcl_AccrueOffsetDriver)(double offset, double corr_rate);
+
+/* System driver to apply a step offset. A positive argument means step
+   the clock forwards. */
+typedef int (*lcl_ApplyStepOffsetDriver)(double offset);
+
+/* System driver to convert a raw time to an adjusted (cooked) time.
+   The number of seconds returned in 'corr' have to be added to the
+   raw time to get the corrected time */
+typedef void (*lcl_OffsetCorrectionDriver)(struct timespec *raw, double *corr, double *err);
+
+/* System driver to schedule leap seconds and set TAI-UTC offset */
+typedef void (*lcl_SetLeapDriver)(int leap, int tai_offset);
+
+/* System driver to set the synchronisation status */
+typedef void (*lcl_SetSyncStatusDriver)(int synchronised, double est_error, double max_error);
+
+extern void lcl_InvokeDispersionNotifyHandlers(double dispersion);
+
+extern void
+lcl_RegisterSystemDrivers(lcl_ReadFrequencyDriver read_freq,
+                          lcl_SetFrequencyDriver set_freq,
+                          lcl_AccrueOffsetDriver accrue_offset,
+                          lcl_ApplyStepOffsetDriver apply_step_offset,
+                          lcl_OffsetCorrectionDriver offset_convert,
+                          lcl_SetLeapDriver set_leap,
+                          lcl_SetSyncStatusDriver set_sync_status);
+
+#endif /* GOT_LOCALP_H */
diff --git a/logging.c b/logging.c
new file mode 100644
index 0000000..22c326c
--- /dev/null
+++ b/logging.c
@@ -0,0 +1,381 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2014, 2018-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module to handle logging of diagnostic information
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <syslog.h>
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+
+/* This is used by DEBUG_LOG macro */
+LOG_Severity log_min_severity = LOGS_INFO;
+
+/* Current logging contexts */
+static LOG_Context log_contexts;
+
+/* ================================================== */
+/* Flag indicating we have initialised */
+static int initialised = 0;
+
+static FILE *file_log = NULL;
+static int system_log = 0;
+
+static int parent_fd = 0;
+
+struct LogFile {
+  const char *name;
+  const char *banner;
+  FILE *file;
+  unsigned long writes;
+};
+
+static int n_filelogs = 0;
+
+/* Increase this when adding a new logfile */
+#define MAX_FILELOGS 6
+
+static struct LogFile logfiles[MAX_FILELOGS];
+
+/* Global prefix for debug messages */
+static char *debug_prefix;
+
+/* ================================================== */
+/* Init function */
+
+void
+LOG_Initialise(void)
+{
+  debug_prefix = Strdup("");
+  log_contexts = 0;
+
+  initialised = 1;
+  LOG_OpenFileLog(NULL);
+}
+
+/* ================================================== */
+/* Fini function */
+
+void
+LOG_Finalise(void)
+{
+  if (system_log)
+    closelog();
+
+  if (file_log)
+    fclose(file_log);
+
+  LOG_CycleLogFiles();
+
+  Free(debug_prefix);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+static void log_message(int fatal, LOG_Severity severity, const char *message)
+{
+  if (system_log) {
+    int priority;
+    switch (severity) {
+      case LOGS_DEBUG:
+        priority = LOG_DEBUG;
+        break;
+      case LOGS_INFO:
+        priority = LOG_INFO;
+        break;
+      case LOGS_WARN:
+        priority = LOG_WARNING;
+        break;
+      case LOGS_ERR:
+        priority = LOG_ERR;
+        break;
+      case LOGS_FATAL:
+        priority = LOG_CRIT;
+        break;
+      default:
+        assert(0);
+    }
+    syslog(priority, fatal ? "Fatal error : %s" : "%s", message);
+  } else if (file_log) {
+    fprintf(file_log, fatal ? "Fatal error : %s\n" : "%s\n", message);
+  }
+}
+
+/* ================================================== */
+
+void LOG_Message(LOG_Severity severity,
+#if DEBUG > 0
+                 int line_number, const char *filename, const char *function_name,
+#endif
+                 const char *format, ...)
+{
+  char buf[2048];
+  va_list other_args;
+  time_t t;
+  struct tm *tm;
+
+  assert(initialised);
+
+  if (!system_log && file_log && severity >= log_min_severity) {
+    /* Don't clutter up syslog with timestamps and internal debugging info */
+    time(&t);
+    tm = gmtime(&t);
+    if (tm) {
+      strftime(buf, sizeof (buf), "%Y-%m-%dT%H:%M:%SZ", tm);
+      fprintf(file_log, "%s ", buf);
+    }
+#if DEBUG > 0
+    if (log_min_severity <= LOGS_DEBUG)
+      fprintf(file_log, "%s%s:%d:(%s) ", debug_prefix, filename, line_number, function_name);
+#endif
+  }
+
+  va_start(other_args, format);
+  vsnprintf(buf, sizeof(buf), format, other_args);
+  va_end(other_args);
+
+  switch (severity) {
+    case LOGS_DEBUG:
+    case LOGS_INFO:
+    case LOGS_WARN:
+    case LOGS_ERR:
+      if (severity >= log_min_severity)
+        log_message(0, severity, buf);
+      break;
+    case LOGS_FATAL:
+      if (severity >= log_min_severity)
+        log_message(1, severity, buf);
+
+      /* Send the message also to the foreground process if it is
+         still running, or stderr if it is still open */
+      if (parent_fd > 0) {
+        if (write(parent_fd, buf, strlen(buf) + 1) < 0)
+          ; /* Not much we can do here */
+      } else if (system_log && parent_fd == 0) {
+        system_log = 0;
+        log_message(1, severity, buf);
+      }
+      exit(1);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+LOG_OpenFileLog(const char *log_file)
+{
+  FILE *f;
+
+  if (log_file) {
+    f = UTI_OpenFile(NULL, log_file, NULL, 'A', 0640);
+  } else {
+    f = stderr;
+  }
+
+  /* Enable line buffering */
+  setvbuf(f, NULL, _IOLBF, BUFSIZ);
+
+  if (file_log && file_log != stderr)
+    fclose(file_log);
+
+  file_log = f;
+}
+
+
+/* ================================================== */
+
+void
+LOG_OpenSystemLog(void)
+{
+  system_log = 1;
+  openlog("chronyd", LOG_PID, LOG_DAEMON);
+}
+
+/* ================================================== */
+
+void LOG_SetMinSeverity(LOG_Severity severity)
+{
+  /* Don't print any debug messages in a non-debug build */
+  log_min_severity = CLAMP(DEBUG > 0 ? LOGS_DEBUG : LOGS_INFO, severity, LOGS_FATAL);
+}
+
+/* ================================================== */
+
+LOG_Severity
+LOG_GetMinSeverity(void)
+{
+  return log_min_severity;
+}
+
+/* ================================================== */
+
+void
+LOG_SetContext(LOG_Context context)
+{
+  log_contexts |= context;
+}
+
+/* ================================================== */
+
+void
+LOG_UnsetContext(LOG_Context context)
+{
+  log_contexts &= ~context;
+}
+
+/* ================================================== */
+
+LOG_Severity
+LOG_GetContextSeverity(LOG_Context contexts)
+{
+  return log_contexts & contexts ? LOGS_INFO : LOGS_DEBUG;
+}
+
+/* ================================================== */
+
+void
+LOG_SetDebugPrefix(const char *prefix)
+{
+  Free(debug_prefix);
+  debug_prefix = Strdup(prefix);
+}
+
+/* ================================================== */
+
+void
+LOG_SetParentFd(int fd)
+{
+  parent_fd = fd;
+  if (file_log == stderr)
+    file_log = NULL;
+}
+
+/* ================================================== */
+
+void
+LOG_CloseParentFd()
+{
+  if (parent_fd > 0)
+    close(parent_fd);
+  parent_fd = -1;
+}
+
+/* ================================================== */
+
+LOG_FileID
+LOG_FileOpen(const char *name, const char *banner)
+{
+  if (n_filelogs >= MAX_FILELOGS) {
+    assert(0);
+    return -1;
+  }
+
+  logfiles[n_filelogs].name = name;
+  logfiles[n_filelogs].banner = banner;
+  logfiles[n_filelogs].file = NULL;
+  logfiles[n_filelogs].writes = 0;
+
+  return n_filelogs++;
+}
+
+/* ================================================== */
+
+void
+LOG_FileWrite(LOG_FileID id, const char *format, ...)
+{
+  va_list other_args;
+  int banner;
+
+  if (id < 0 || id >= n_filelogs || !logfiles[id].name)
+    return;
+
+  if (!logfiles[id].file) {
+    char *logdir = CNF_GetLogDir();
+
+    if (!logdir) {
+      LOG(LOGS_WARN, "logdir not specified");
+      logfiles[id].name = NULL;
+      return;
+    }
+
+    logfiles[id].file = UTI_OpenFile(logdir, logfiles[id].name, ".log", 'a', 0644);
+    if (!logfiles[id].file) {
+      /* Disable the log */
+      logfiles[id].name = NULL;
+      return;
+    }
+  }
+
+  banner = CNF_GetLogBanner();
+  if (banner && logfiles[id].writes++ % banner == 0) {
+    char bannerline[256];
+    int i, bannerlen;
+
+    bannerlen = MIN(strlen(logfiles[id].banner), sizeof (bannerline) - 1);
+
+    for (i = 0; i < bannerlen; i++)
+      bannerline[i] = '=';
+    bannerline[i] = '\0';
+
+    fprintf(logfiles[id].file, "%s\n", bannerline);
+    fprintf(logfiles[id].file, "%s\n", logfiles[id].banner);
+    fprintf(logfiles[id].file, "%s\n", bannerline);
+  }
+
+  va_start(other_args, format);
+  vfprintf(logfiles[id].file, format, other_args);
+  va_end(other_args);
+  fprintf(logfiles[id].file, "\n");
+
+  fflush(logfiles[id].file);
+}
+
+/* ================================================== */
+
+void
+LOG_CycleLogFiles(void)
+{
+  LOG_FileID i;
+
+  for (i = 0; i < n_filelogs; i++) {
+    if (logfiles[i].file)
+      fclose(logfiles[i].file);
+    logfiles[i].file = NULL;
+    logfiles[i].writes = 0;
+  }
+}
+
+/* ================================================== */
diff --git a/logging.h b/logging.h
new file mode 100644
index 0000000..ff2e30e
--- /dev/null
+++ b/logging.h
@@ -0,0 +1,143 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2013-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for diagnostic logging module
+
+  */
+
+#ifndef GOT_LOGGING_H
+#define GOT_LOGGING_H
+
+#include "sysincl.h"
+
+/* Line logging macros.  If the compiler is GNU C, we take advantage of
+   being able to get the function name also. */
+
+#ifdef __GNUC__
+#define FUNCTION_NAME __FUNCTION__
+#define FORMAT_ATTRIBUTE_PRINTF(str, first) __attribute__ ((format (printf, str, first)))
+#else
+#define FUNCTION_NAME ""
+#define FORMAT_ATTRIBUTE_PRINTF(str, first)
+#endif
+
+#if DEBUG > 0
+#define LOG_MESSAGE(severity, ...) \
+  LOG_Message(severity, __LINE__, __FILE__, FUNCTION_NAME, __VA_ARGS__)
+#else
+#define LOG_MESSAGE(severity, ...) \
+  LOG_Message(severity, __VA_ARGS__)
+#endif
+
+#define DEBUG_LOG(...) \
+  do { \
+    if (DEBUG && log_min_severity == LOGS_DEBUG) \
+      LOG_MESSAGE(LOGS_DEBUG, __VA_ARGS__); \
+  } while (0)
+
+#define LOG_FATAL(...) \
+  do { \
+    LOG_MESSAGE(LOGS_FATAL, __VA_ARGS__); \
+    exit(1); \
+  } while (0)
+
+#define LOG(severity, ...) LOG_MESSAGE(severity, __VA_ARGS__)
+
+/* Definition of severity */
+typedef enum {
+  LOGS_DEBUG = -1,
+  LOGS_INFO = 0,
+  LOGS_WARN,
+  LOGS_ERR,
+  LOGS_FATAL,
+} LOG_Severity;
+
+/* Minimum severity of messages to be logged */
+extern LOG_Severity log_min_severity;
+
+/* Init function */
+extern void LOG_Initialise(void);
+
+/* Fini function */
+extern void LOG_Finalise(void);
+
+/* Line logging function */
+#if DEBUG > 0
+FORMAT_ATTRIBUTE_PRINTF(5, 6)
+extern void LOG_Message(LOG_Severity severity, int line_number, const char *filename,
+                        const char *function_name, const char *format, ...);
+#else
+FORMAT_ATTRIBUTE_PRINTF(2, 3)
+extern void LOG_Message(LOG_Severity severity, const char *format, ...);
+#endif
+
+/* Set the minimum severity of a message to be logged or printed to terminal.
+   If the severity is LOGS_DEBUG and DEBUG is enabled, all messages will be
+   prefixed with the filename, line number, and function name. */
+extern void LOG_SetMinSeverity(LOG_Severity severity);
+
+/* Get the minimum severity */
+extern LOG_Severity LOG_GetMinSeverity(void);
+
+/* Flags for info messages that should be logged only in specific contexts */
+typedef enum {
+  LOGC_Command = 1,
+  LOGC_SourceFile = 2,
+} LOG_Context;
+
+/* Modify current contexts */
+extern void LOG_SetContext(LOG_Context context);
+extern void LOG_UnsetContext(LOG_Context context);
+
+/* Get severity depending on the current active contexts: INFO if they contain
+   at least one of the specified contexts, DEBUG otherwise */
+extern LOG_Severity LOG_GetContextSeverity(LOG_Context contexts);
+
+/* Set a prefix for debug messages */
+extern void LOG_SetDebugPrefix(const char *prefix);
+
+/* Log messages to a file instead of stderr, or stderr again if NULL */
+extern void LOG_OpenFileLog(const char *log_file);
+
+/* Log messages to syslog instead of stderr */
+extern void LOG_OpenSystemLog(void);
+
+/* Stop using stderr and send fatal message to the foreground process */
+extern void LOG_SetParentFd(int fd);
+
+/* Close the pipe to the foreground process so it can exit */
+extern void LOG_CloseParentFd(void);
+
+/* File logging functions */
+
+typedef int LOG_FileID;
+
+extern LOG_FileID LOG_FileOpen(const char *name, const char *banner);
+
+FORMAT_ATTRIBUTE_PRINTF(2, 3)
+extern void LOG_FileWrite(LOG_FileID id, const char *format, ...);
+
+extern void LOG_CycleLogFiles(void);
+
+#endif /* GOT_LOGGING_H */
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..3233707
--- /dev/null
+++ b/main.c
@@ -0,0 +1,703 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2012-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The main program
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "main.h"
+#include "sched.h"
+#include "local.h"
+#include "sys.h"
+#include "ntp_io.h"
+#include "ntp_signd.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "nts_ke_server.h"
+#include "nts_ntp_server.h"
+#include "socket.h"
+#include "sources.h"
+#include "sourcestats.h"
+#include "reference.h"
+#include "logging.h"
+#include "conf.h"
+#include "cmdmon.h"
+#include "keys.h"
+#include "manual.h"
+#include "rtc.h"
+#include "refclock.h"
+#include "clientlog.h"
+#include "nameserv.h"
+#include "privops.h"
+#include "smooth.h"
+#include "tempcomp.h"
+#include "util.h"
+
+/* ================================================== */
+
+/* Set when the initialisation chain has been completed.  Prevents finalisation
+ * chain being run if a fatal error happened early. */
+
+static int initialised = 0;
+
+static int exit_status = 0;
+
+static int reload = 0;
+
+static REF_Mode ref_mode = REF_ModeNormal;
+
+/* ================================================== */
+
+static void
+do_platform_checks(void)
+{
+  struct timespec ts;
+
+  /* Require at least 32-bit integers, two's complement representation and
+     the usual implementation of conversion of unsigned integers */
+  assert(sizeof (int) >= 4);
+  assert(-1 == ~0);
+  assert((int32_t)4294967295U == (int32_t)-1);
+
+  /* Require time_t and tv_nsec in timespec to be signed */
+  ts.tv_sec = -1;
+  ts.tv_nsec = -1;
+  assert(ts.tv_sec < 0 && ts.tv_nsec < 0);
+}
+
+/* ================================================== */
+
+static void
+delete_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+
+  if (!pidfile)
+    return;
+
+  if (!UTI_RemoveFile(NULL, pidfile, NULL))
+    ;
+}
+
+/* ================================================== */
+
+void
+MAI_CleanupAndExit(void)
+{
+  if (!initialised) exit(exit_status);
+  
+  LCL_CancelOffsetCorrection();
+  SRC_DumpSources();
+
+  /* Don't update clock when removing sources */
+  REF_SetMode(REF_ModeIgnore);
+
+  SMT_Finalise();
+  TMC_Finalise();
+  MNL_Finalise();
+  CLG_Finalise();
+  NKS_Finalise();
+  NNS_Finalise();
+  NSD_Finalise();
+  NSR_Finalise();
+  SST_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  CAM_Finalise();
+
+  KEY_Finalise();
+  RCL_Finalise();
+  SRC_Finalise();
+  REF_Finalise();
+  RTC_Finalise();
+  SYS_Finalise();
+
+  SCK_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+
+  delete_pidfile();
+  
+  CNF_Finalise();
+  HSH_Finalise();
+  LOG_Finalise();
+
+  UTI_ResetGetRandomFunctions();
+
+  exit(exit_status);
+}
+
+/* ================================================== */
+
+static void
+signal_cleanup(int x)
+{
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+quit_timeout(void *arg)
+{
+  LOG(LOGS_INFO, "Timeout reached");
+
+  /* Return with non-zero status if the clock is not synchronised */
+  exit_status = REF_GetOurStratum() >= NTP_MAX_STRATUM;
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static void
+ntp_source_resolving_end(void)
+{
+  NSR_SetSourceResolvingEndHandler(NULL);
+
+  if (reload) {
+    /* Note, we want reload to come well after the initialisation from
+       the real time clock - this gives us a fighting chance that the
+       system-clock scale for the reloaded samples still has a
+       semblence of validity about it. */
+    SRC_ReloadSources();
+  }
+
+  SRC_RemoveDumpFiles();
+  RTC_StartMeasurements();
+  RCL_StartRefclocks();
+  NSR_StartSources();
+  NSR_AutoStartSources();
+
+  /* Special modes can end only when sources update their reachability.
+     Give up immediately if there are no active sources. */
+  if (ref_mode != REF_ModeNormal && !SRC_ActiveSources()) {
+    REF_SetUnsynchronised();
+  }
+}
+
+/* ================================================== */
+
+static void
+post_init_ntp_hook(void *anything)
+{
+  if (ref_mode == REF_ModeInitStepSlew) {
+    /* Remove the initstepslew sources and set normal mode */
+    NSR_RemoveAllSources();
+    ref_mode = REF_ModeNormal;
+    REF_SetMode(ref_mode);
+  }
+
+  /* Close the pipe to the foreground process so it can exit */
+  LOG_CloseParentFd();
+
+  CNF_AddSources();
+  CNF_AddBroadcasts();
+
+  NSR_SetSourceResolvingEndHandler(ntp_source_resolving_end);
+  NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+static void
+reference_mode_end(int result)
+{
+  switch (ref_mode) {
+    case REF_ModeNormal:
+    case REF_ModeUpdateOnce:
+    case REF_ModePrintOnce:
+      exit_status = !result;
+      SCH_QuitProgram();
+      break;
+    case REF_ModeInitStepSlew:
+      /* Switch to the normal mode, the delay is used to prevent polling
+         interval shorter than the burst interval if some configured servers
+         were used also for initstepslew */
+      SCH_AddTimeoutByDelay(2.0, post_init_ntp_hook, NULL);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+post_init_rtc_hook(void *anything)
+{
+  if (CNF_GetInitSources() > 0) {
+    CNF_AddInitSources();
+    NSR_StartSources();
+    assert(REF_GetMode() != REF_ModeNormal);
+    /* Wait for mode end notification */
+  } else {
+    (post_init_ntp_hook)(NULL);
+  }
+}
+
+/* ================================================== */
+
+static void
+check_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+  FILE *in;
+  int pid, count;
+  
+  if (!pidfile)
+    return;
+
+  in = UTI_OpenFile(NULL, pidfile, NULL, 'r', 0);
+  if (!in)
+    return;
+
+  count = fscanf(in, "%d", &pid);
+  fclose(in);
+  
+  if (count != 1)
+    return;
+
+  if (getsid(pid) < 0)
+    return;
+
+  LOG_FATAL("Another chronyd may already be running (pid=%d), check %s",
+            pid, pidfile);
+}
+
+/* ================================================== */
+
+static void
+write_pidfile(void)
+{
+  const char *pidfile = CNF_GetPidFile();
+  FILE *out;
+
+  if (!pidfile)
+    return;
+
+  out = UTI_OpenFile(NULL, pidfile, NULL, 'W', 0644);
+  fprintf(out, "%d\n", (int)getpid());
+  fclose(out);
+}
+
+/* ================================================== */
+
+#define DEV_NULL "/dev/null"
+
+static void
+go_daemon(void)
+{
+  int pid, fd, pipefd[2];
+
+  /* Create pipe which will the daemon use to notify the grandparent
+     when it's initialised or send an error message */
+  if (pipe(pipefd)) {
+    LOG_FATAL("pipe() failed : %s", strerror(errno));
+  }
+
+  /* Does this preserve existing signal handlers? */
+  pid = fork();
+
+  if (pid < 0) {
+    LOG_FATAL("fork() failed : %s", strerror(errno));
+  } else if (pid > 0) {
+    /* In the 'grandparent' */
+    char message[1024];
+    int r;
+
+    /* Don't exit before the 'parent' */
+    waitpid(pid, NULL, 0);
+
+    close(pipefd[1]);
+    r = read(pipefd[0], message, sizeof (message));
+    if (r) {
+      if (r > 0) {
+        /* Print the error message from the child */
+        message[sizeof (message) - 1] = '\0';
+        fprintf(stderr, "%s\n", message);
+      }
+      exit(1);
+    } else
+      exit(0);
+  } else {
+    close(pipefd[0]);
+
+    setsid();
+
+    /* Do 2nd fork, as-per recommended practice for launching daemons. */
+    pid = fork();
+
+    if (pid < 0) {
+      LOG_FATAL("fork() failed : %s", strerror(errno));
+    } else if (pid > 0) {
+      /* In the 'parent' */
+      close(pipefd[1]);
+      exit(0);
+    } else {
+      /* In the child we want to leave running as the daemon */
+
+      /* Change current directory to / */
+      if (chdir("/") < 0) {
+        LOG_FATAL("chdir() failed : %s", strerror(errno));
+      }
+
+      /* Don't keep stdin/out/err from before. But don't close
+         the parent pipe yet. */
+      for (fd=0; fd<1024; fd++) {
+        if (fd != pipefd[1])
+          close(fd);
+      }
+
+      LOG_SetParentFd(pipefd[1]);
+
+      /* Open /dev/null as new stdin/out/err */
+      errno = 0;
+      if (open(DEV_NULL, O_RDONLY) != STDIN_FILENO ||
+          open(DEV_NULL, O_WRONLY) != STDOUT_FILENO ||
+          open(DEV_NULL, O_RDWR) != STDERR_FILENO)
+        LOG_FATAL("Could not open %s : %s", DEV_NULL, strerror(errno));
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+print_help(const char *progname)
+{
+      printf("Usage: %s [OPTION]... [DIRECTIVE]...\n\n"
+             "Options:\n"
+             "  -4\t\tUse IPv4 addresses only\n"
+             "  -6\t\tUse IPv6 addresses only\n"
+             "  -f FILE\tSpecify configuration file (%s)\n"
+             "  -n\t\tDon't run as daemon\n"
+             "  -d\t\tDon't run as daemon and log to stderr\n"
+#if DEBUG > 0
+             "  -d -d\t\tEnable debug messages\n"
+#endif
+             "  -l FILE\tLog to file\n"
+             "  -L LEVEL\tSet logging threshold (0)\n"
+             "  -p\t\tPrint configuration and exit\n"
+             "  -q\t\tSet clock and exit\n"
+             "  -Q\t\tLog offset and exit\n"
+             "  -r\t\tReload dump files\n"
+             "  -R\t\tAdapt configuration for restart\n"
+             "  -s\t\tSet clock from RTC\n"
+             "  -t SECONDS\tExit after elapsed time\n"
+             "  -u USER\tSpecify user (%s)\n"
+             "  -U\t\tDon't check for root\n"
+             "  -F LEVEL\tSet system call filter level (0)\n"
+             "  -P PRIORITY\tSet process priority (0)\n"
+             "  -m\t\tLock memory\n"
+             "  -x\t\tDon't control clock\n"
+             "  -v, --version\tPrint version and exit\n"
+             "  -h, --help\tPrint usage and exit\n",
+             progname, DEFAULT_CONF_FILE, DEFAULT_USER);
+}
+
+/* ================================================== */
+
+static void
+print_version(void)
+{
+  printf("chronyd (chrony) version %s (%s)\n", CHRONY_VERSION, CHRONYD_FEATURES);
+}
+
+/* ================================================== */
+
+static int
+parse_int_arg(const char *arg)
+{
+  int i;
+
+  if (sscanf(arg, "%d", &i) != 1)
+    LOG_FATAL("Invalid argument %s", arg);
+  return i;
+}
+
+/* ================================================== */
+
+int main
+(int argc, char **argv)
+{
+  const char *conf_file = DEFAULT_CONF_FILE;
+  const char *progname = argv[0];
+  char *user = NULL, *log_file = NULL;
+  struct passwd *pw;
+  int opt, debug = 0, nofork = 0, address_family = IPADDR_UNSPEC;
+  int do_init_rtc = 0, restarted = 0, client_only = 0, timeout = -1;
+  int scfilter_level = 0, lock_memory = 0, sched_priority = 0;
+  int clock_control = 1, system_log = 1, log_severity = LOGS_INFO;
+  int user_check = 1, config_args = 0, print_config = 0;
+
+  do_platform_checks();
+
+  LOG_Initialise();
+
+  /* Parse long command-line options */
+  for (optind = 1; optind < argc; optind++) {
+    if (!strcmp("--help", argv[optind])) {
+      print_help(progname);
+      return 0;
+    } else if (!strcmp("--version", argv[optind])) {
+      print_version();
+      return 0;
+    }
+  }
+
+  optind = 1;
+
+  /* Parse short command-line options */
+  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnpP:qQrRst:u:Uvx")) != -1) {
+    switch (opt) {
+      case '4':
+      case '6':
+        address_family = opt == '4' ? IPADDR_INET4 : IPADDR_INET6;
+        break;
+      case 'd':
+        debug++;
+        nofork = 1;
+        system_log = 0;
+        break;
+      case 'f':
+        conf_file = optarg;
+        break;
+      case 'F':
+        scfilter_level = parse_int_arg(optarg);
+        break;
+      case 'l':
+        log_file = optarg;
+        break;
+      case 'L':
+        log_severity = parse_int_arg(optarg);
+        break;
+      case 'm':
+        lock_memory = 1;
+        break;
+      case 'n':
+        nofork = 1;
+        break;
+      case 'p':
+        print_config = 1;
+        user_check = 0;
+        nofork = 1;
+        system_log = 0;
+        log_severity = LOGS_WARN;
+        break;
+      case 'P':
+        sched_priority = parse_int_arg(optarg);
+        break;
+      case 'q':
+        ref_mode = REF_ModeUpdateOnce;
+        nofork = 1;
+        client_only = 0;
+        system_log = 0;
+        break;
+      case 'Q':
+        ref_mode = REF_ModePrintOnce;
+        nofork = 1;
+        client_only = 1;
+        user_check = 0;
+        clock_control = 0;
+        system_log = 0;
+        break;
+      case 'r':
+        reload = 1;
+        break;
+      case 'R':
+        restarted = 1;
+        break;
+      case 's':
+        do_init_rtc = 1;
+        break;
+      case 't':
+        timeout = parse_int_arg(optarg);
+        break;
+      case 'u':
+        user = optarg;
+        break;
+      case 'U':
+        user_check = 0;
+        break;
+      case 'v':
+        print_version();
+        return 0;
+      case 'x':
+        clock_control = 0;
+        break;
+      default:
+        print_help(progname);
+        return opt != 'h';
+    }
+  }
+
+  if (user_check && getuid() != 0)
+    LOG_FATAL("Not superuser");
+
+  /* Turn into a daemon */
+  if (!nofork) {
+    go_daemon();
+  }
+
+  if (log_file) {
+    LOG_OpenFileLog(log_file);
+  } else if (system_log) {
+    LOG_OpenSystemLog();
+  }
+  
+  LOG_SetMinSeverity(debug >= 2 ? LOGS_DEBUG : log_severity);
+  
+  LOG(LOGS_INFO, "chronyd version %s starting (%s)", CHRONY_VERSION, CHRONYD_FEATURES);
+
+  DNS_SetAddressFamily(address_family);
+
+  CNF_Initialise(restarted, client_only);
+  if (print_config)
+    CNF_EnablePrint();
+
+  /* Parse the config file or the remaining command line arguments */
+  config_args = argc - optind;
+  if (!config_args) {
+    CNF_ReadFile(conf_file);
+  } else {
+    for (; optind < argc; optind++)
+      CNF_ParseLine(NULL, config_args + optind - argc + 1, argv[optind]);
+  }
+
+  if (print_config)
+    return 0;
+
+  /* Check whether another chronyd may already be running */
+  check_pidfile();
+
+  if (!user)
+    user = CNF_GetUser();
+
+  pw = getpwnam(user);
+  if (!pw)
+    LOG_FATAL("Could not get user/group ID of %s", user);
+
+  /* Create directories for sockets, log files, and dump files */
+  CNF_CreateDirs(pw->pw_uid, pw->pw_gid);
+
+  /* Write our pidfile to prevent other instances from running */
+  write_pidfile();
+
+  PRV_Initialise();
+  LCL_Initialise();
+  SCH_Initialise();
+  SCK_Initialise(address_family);
+
+  /* Start helper processes if needed */
+  NKS_PreInitialise(pw->pw_uid, pw->pw_gid, scfilter_level);
+
+  SYS_Initialise(clock_control);
+  RTC_Initialise(do_init_rtc);
+  SRC_Initialise();
+  RCL_Initialise();
+  KEY_Initialise();
+
+  /* Open privileged ports before dropping root */
+  CAM_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  CNF_SetupAccessRestrictions();
+
+  /* Command-line switch must have priority */
+  if (!sched_priority) {
+    sched_priority = CNF_GetSchedPriority();
+  }
+  if (sched_priority) {
+    SYS_SetScheduler(sched_priority);
+  }
+
+  if (lock_memory || CNF_GetLockMemory()) {
+    SYS_LockMemory();
+  }
+
+  /* Drop root privileges if the specified user has a non-zero UID */
+  if (!geteuid() && (pw->pw_uid || pw->pw_gid)) {
+    SYS_DropRoot(pw->pw_uid, pw->pw_gid, SYS_MAIN_PROCESS);
+
+    /* Warn if missing read access or having write access to keys */
+    CNF_CheckReadOnlyAccess();
+  }
+
+  if (!geteuid())
+    LOG(LOGS_WARN, "Running with root privileges");
+
+  REF_Initialise();
+  SST_Initialise();
+  NSR_Initialise();
+  NSD_Initialise();
+  NNS_Initialise();
+  NKS_Initialise();
+  CLG_Initialise();
+  MNL_Initialise();
+  TMC_Initialise();
+  SMT_Initialise();
+
+  /* From now on, it is safe to do finalisation on exit */
+  initialised = 1;
+
+  UTI_SetQuitSignalsHandler(signal_cleanup, 1);
+
+  CAM_OpenUnixSocket();
+
+  if (scfilter_level)
+    SYS_EnableSystemCallFilter(scfilter_level, SYS_MAIN_PROCESS);
+
+  if (ref_mode == REF_ModeNormal && CNF_GetInitSources() > 0) {
+    ref_mode = REF_ModeInitStepSlew;
+  }
+
+  REF_SetModeEndHandler(reference_mode_end);
+  REF_SetMode(ref_mode);
+
+  if (timeout >= 0)
+    SCH_AddTimeoutByDelay(timeout, quit_timeout, NULL);
+
+  if (do_init_rtc) {
+    RTC_TimeInit(post_init_rtc_hook, NULL);
+  } else {
+    post_init_rtc_hook(NULL);
+  }
+
+  /* The program normally runs under control of the main loop in
+     the scheduler. */
+  SCH_MainLoop();
+
+  LOG(LOGS_INFO, "chronyd exiting");
+
+  MAI_CleanupAndExit();
+
+  return 0;
+}
+
+/* ================================================== */
diff --git a/main.h b/main.h
new file mode 100644
index 0000000..d6d502a
--- /dev/null
+++ b/main.h
@@ -0,0 +1,35 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for main routine
+  */
+
+#ifndef GOT_MAIN_H
+#define GOT_MAIN_H
+
+/* Function to clean up at end of run */
+extern void MAI_CleanupAndExit(void);
+
+#endif /* GOT_MAIN_H */
+
+
diff --git a/manual.c b/manual.c
new file mode 100644
index 0000000..98a3aa2
--- /dev/null
+++ b/manual.c
@@ -0,0 +1,332 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines for implementing manual input of real time.
+
+  The daemon accepts manual time input over the control connection,
+  and adjusts the system time to match.  Besides this, though, it can
+  determine the average rate of time loss or gain of the local system
+  and adjust the frequency accordingly.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "manual.h"
+#include "logging.h"
+#include "local.h"
+#include "conf.h"
+#include "util.h"
+#include "ntp.h"
+#include "reference.h"
+#include "regress.h"
+
+static int enabled = 0;
+
+/* More recent samples at highest indices */
+typedef struct {
+  struct timespec when; /* This is our 'cooked' time */
+  double orig_offset; /*+ Not modified by slew samples */
+  double offset; /*+ if we are fast of the supplied reference */
+  double residual; /*+ regression residual (sign convention given by
+                     (measured-predicted)) */
+} Sample;
+
+#define MIN_SAMPLE_SEPARATION 1.0
+
+#define MAX_SAMPLES 16
+
+static Sample samples[16];
+static int n_samples;
+
+/* ================================================== */
+
+static void
+slew_samples(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *not_used);
+
+/* ================================================== */
+
+void
+MNL_Initialise(void)
+{
+  if (CNF_GetManualEnabled()) {
+    enabled = 1;
+  } else {
+    enabled = 0;
+  }
+
+  n_samples = 0;
+
+  LCL_AddParameterChangeHandler(slew_samples, NULL);
+}
+
+/* ================================================== */
+
+void
+MNL_Finalise(void)
+{
+  LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+}
+
+/* ================================================== */
+
+static void
+estimate_and_set_system(struct timespec *now, int offset_provided, double offset,
+                        double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm)
+{
+  double agos[MAX_SAMPLES], offsets[MAX_SAMPLES];
+  double b0, b1;
+  int n_runs, best_start; /* Unused results from regression analyser */
+  int i;
+  double freq = 0.0;
+  double skew = 0.099999999; /* All 9's when printed to log file */
+  int found_freq;
+  double slew_by;
+
+  b0 = offset_provided ? offset : 0.0;
+  b1 = freq = 0.0;
+  found_freq = 0;
+
+  if (n_samples > 1) {
+    for (i=0; i<n_samples; i++) {
+      agos[i] = UTI_DiffTimespecsToDouble(&samples[n_samples - 1].when, &samples[i].when);
+      offsets[i] = samples[i].offset;
+    }
+    
+    if (RGR_FindBestRobustRegression(agos, offsets, n_samples, 1.0e-8,
+                                     &b0, &b1, &n_runs, &best_start)) {
+      /* Ignore b0 from regression; treat offset as being the most
+         recently entered value.  (If the administrator knows he's put
+         an outlier in, he will rerun the settime operation.)   However,
+         the frequency estimate comes from the regression. */
+      freq = -b1;
+      found_freq = 1;
+    }
+  } else {
+    agos[0] = 0.0;
+    offsets[0] = b0;
+  }
+
+  if (offset_provided) {
+    slew_by = offset;
+  } else {
+    slew_by = b0;
+  }
+  
+  if (found_freq) {
+    LOG(LOGS_INFO, "Making a frequency change of %.3f ppm and a slew of %.6f",
+        1.0e6 * freq, slew_by);
+    
+    REF_SetManualReference(now,
+                           slew_by,
+                           freq, skew);
+  } else {
+    LOG(LOGS_INFO, "Making a slew of %.6f", slew_by);
+    REF_SetManualReference(now,
+                           slew_by,
+                           0.0, skew);
+  }
+  
+  if (reg_offset) *reg_offset = b0;
+  if (dfreq_ppm) *dfreq_ppm = 1.0e6 * freq;
+  if (new_afreq_ppm) *new_afreq_ppm = LCL_ReadAbsoluteFrequency();
+  
+  /* Calculate residuals to store them */
+  for (i=0; i<n_samples; i++) {
+    samples[i].residual = offsets[i] - (b0 + agos[i] * b1);
+  }
+  
+}
+
+/* ================================================== */
+
+int
+MNL_AcceptTimestamp(struct timespec *ts, double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm)
+{
+  struct timespec now;
+  double offset, diff;
+  int i;
+
+  if (enabled) {
+    LCL_ReadCookedTime(&now, NULL);
+
+    /* Make sure the provided timestamp is sane and the sample
+       is not too close to the last one */
+
+    if (!UTI_IsTimeOffsetSane(ts, 0.0))
+     return 0;
+
+    if (n_samples) {
+      diff = UTI_DiffTimespecsToDouble(&now, &samples[n_samples - 1].when);
+      if (diff < MIN_SAMPLE_SEPARATION)
+        return 0;
+    }
+
+    offset = UTI_DiffTimespecsToDouble(&now, ts);
+
+    /* Check if buffer full up */
+    if (n_samples == MAX_SAMPLES) {
+      /* Shift samples down */
+      for (i=1; i<n_samples; i++) {
+        samples[i-1] = samples[i];
+      }
+      --n_samples;
+    }
+    
+    samples[n_samples].when = now;
+    samples[n_samples].offset = offset;
+    samples[n_samples].orig_offset = offset;
+    ++n_samples;
+
+    estimate_and_set_system(&now, 1, offset, reg_offset, dfreq_ppm, new_afreq_ppm);
+
+    return 1;
+
+  } else {
+  
+    return 0;
+
+  }
+}
+
+/* ================================================== */
+
+static void
+slew_samples(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *not_used)
+{
+  double delta_time;
+  int i;
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    MNL_Reset();
+  }
+
+  for (i=0; i<n_samples; i++) {
+    UTI_AdjustTimespec(&samples[i].when, cooked, &samples[i].when, &delta_time,
+        dfreq, doffset);
+    samples[i].offset += delta_time;
+  }
+}
+
+/* ================================================== */
+
+void
+MNL_Enable(void)
+{
+  enabled = 1;
+}
+
+
+/* ================================================== */
+
+void
+MNL_Disable(void)
+{
+  enabled = 0;
+}
+
+/* ================================================== */
+
+void
+MNL_Reset(void)
+{
+  n_samples = 0;
+}
+
+/* ================================================== */
+
+int
+MNL_IsEnabled(void)
+{
+  return enabled;
+}
+
+/* ================================================== */
+/* Generate report data for the REQ_MANUAL_LIST command/monitoring
+   protocol */
+
+void
+MNL_ReportSamples(RPT_ManualSamplesReport *report, int max, int *n)
+{
+  int i;
+
+  if (n_samples > max) {
+    *n = max;
+  } else {
+    *n = n_samples;
+  }
+
+  for (i=0; i<n_samples && i<max; i++) {
+    report[i].when = samples[i].when;
+    report[i].slewed_offset = samples[i].offset;
+    report[i].orig_offset = samples[i].orig_offset;
+    report[i].residual = samples[i].residual;
+  }
+}
+
+/* ================================================== */
+/* Delete a sample if it's within range, re-estimate the error and
+   drift and apply it to the system clock. */
+
+int
+MNL_DeleteSample(int index)
+{
+  int i;
+  struct timespec now;
+
+  if ((index < 0) || (index >= n_samples)) {
+    return 0;
+  }
+
+  /* Crunch the samples down onto the one being deleted */
+
+  for (i=index; i<(n_samples-1); i++) {
+    samples[i] = samples[i+1];
+  }
+  
+  n_samples -= 1;
+
+  /* Now re-estimate.  NULLs because we don't want the parameters back
+     in this case. */
+  LCL_ReadCookedTime(&now, NULL);
+  estimate_and_set_system(&now, 0, 0.0, NULL, NULL, NULL);
+
+  return 1;
+
+}
+
+/* ================================================== */
+
+
diff --git a/manual.h b/manual.h
new file mode 100644
index 0000000..7f3d0b2
--- /dev/null
+++ b/manual.h
@@ -0,0 +1,46 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for manual time input module.
+
+  */
+
+#ifndef GOT_MANUAL_H
+#define GOT_MANUAL_H
+
+#include "sysincl.h"
+#include "reports.h"
+
+extern void MNL_Initialise(void);
+extern void MNL_Finalise(void);
+extern int MNL_AcceptTimestamp(struct timespec *ts, double *reg_offset, double *dfreq_ppm, double *new_afreq_ppm);
+
+extern void MNL_Enable(void);
+extern void MNL_Disable(void);
+extern void MNL_Reset(void);
+extern int MNL_IsEnabled(void);
+
+extern void MNL_ReportSamples(RPT_ManualSamplesReport *report, int max, int *n);
+extern int MNL_DeleteSample(int index);
+
+#endif /* GOT_MANUAL_H */
diff --git a/md5.c b/md5.c
new file mode 100644
index 0000000..b8eeda3
--- /dev/null
+++ b/md5.c
@@ -0,0 +1,315 @@
+/*
+ ***********************************************************************
+ ** md5.c -- the source code for MD5 routines                         **
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 1/91 SRD,AJ,BSK,JT Reference C Version                   **
+ ** Revised (for MD5): RLR 4/27/91                                    **
+ **   -- G modified to have y&~z instead of y&z                       **
+ **   -- FF, GG, HH modified to add in last register done             **
+ **   -- Access pattern: round 2 works mod 5, round 3 works mod 3     **
+ **   -- distinct additive constant for each step                     **
+ **   -- round 4 added, working mod 7                                 **
+ ***********************************************************************
+ */
+
+/*
+ ***********************************************************************
+ ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
+ **                                                                   **
+ ** License to copy and use this software is granted provided that    **
+ ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
+ ** Digest Algorithm" in all material mentioning or referencing this  **
+ ** software or this function.                                        **
+ **                                                                   **
+ ** License is also granted to make and use derivative works          **
+ ** provided that such works are identified as "derived from the RSA  **
+ ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
+ ** material mentioning or referencing the derived work.              **
+ **                                                                   **
+ ** RSA Data Security, Inc. makes no representations concerning       **
+ ** either the merchantability of this software or the suitability    **
+ ** of this software for any particular purpose.  It is provided "as  **
+ ** is" without express or implied warranty of any kind.              **
+ **                                                                   **
+ ** These notices must be retained in any copies of any part of this  **
+ ** documentation and/or software.                                    **
+ ***********************************************************************
+ */
+
+#include "md5.h"
+
+/*
+ ***********************************************************************
+ **  Message-digest routines:                                         **
+ **  To form the message digest for a message M                       **
+ **    (1) Initialize a context buffer mdContext using MD5Init        **
+ **    (2) Call MD5Update on mdContext and M                          **
+ **    (3) Call MD5Final on mdContext                                 **
+ **  The message digest is now in mdContext->digest[0...15]           **
+ ***********************************************************************
+ */
+
+/* forward declaration */
+static void Transform (UINT4 *, UINT4 *);
+
+#ifdef	__STDC__
+static const
+#else
+static
+#endif
+unsigned char PADDING[64] = {
+  0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+
+/* F, G, H and I are basic MD5 functions */
+#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
+#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+#define I(x, y, z) ((y) ^ ((x) | (~z)))
+
+/* ROTATE_LEFT rotates x left n bits */
+#if	defined(FAST_MD5) && defined(__GNUC__) && defined(mc68000)
+/*
+ * If we're on a 68000 based CPU and using a GNU C compiler with
+ * inline assembly code, we can speed this up a bit.
+ */
+inline UINT4 ROTATE_LEFT(UINT4 x, int n)
+{   
+    asm("roll %2,%0" : "=d" (x) : "0" (x), "Ir" (n));
+    return x;
+}
+#else
+#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
+#endif
+
+
+/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
+/* Rotation is separate from addition to prevent recomputation */
+#define FF(a, b, c, d, x, s, ac) \
+  {(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define GG(a, b, c, d, x, s, ac) \
+  {(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define HH(a, b, c, d, x, s, ac) \
+  {(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+#define II(a, b, c, d, x, s, ac) \
+  {(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
+   (a) = ROTATE_LEFT ((a), (s)); \
+   (a) += (b); \
+  }
+
+/* The routine MD5Init initializes the message-digest context
+   mdContext. All fields are set to zero.
+ */
+void MD5Init (MD5_CTX *mdContext)
+{
+  mdContext->i[0] = mdContext->i[1] = (UINT4)0;
+
+  /* Load magic initialization constants.
+   */
+  mdContext->buf[0] = (UINT4)0x67452301;
+  mdContext->buf[1] = (UINT4)0xefcdab89;
+  mdContext->buf[2] = (UINT4)0x98badcfe;
+  mdContext->buf[3] = (UINT4)0x10325476;
+}
+
+/* The routine MD5Update updates the message-digest context to
+   account for the presence of each of the characters inBuf[0..inLen-1]
+   in the message whose digest is being computed.
+ */
+void MD5Update (MD5_CTX *mdContext, unsigned const char *inBuf, unsigned int inLen)
+{
+  UINT4 in[16];
+  int mdi;
+  unsigned int i, ii;
+
+  /* compute number of bytes mod 64 */
+  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);
+
+  /* update number of bits */
+  if ((mdContext->i[0] + ((UINT4)inLen << 3)) < mdContext->i[0])
+    mdContext->i[1]++;
+  mdContext->i[0] += ((UINT4)inLen << 3);
+  mdContext->i[1] += ((UINT4)inLen >> 29);
+
+  while (inLen--) {
+    /* add new character to buffer, increment mdi */
+    mdContext->in[mdi++] = *inBuf++;
+
+    /* transform if necessary */
+    if (mdi == 0x40) {
+      for (i = 0, ii = 0; i < 16; i++, ii += 4)
+        in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
+                (((UINT4)mdContext->in[ii+2]) << 16) |
+                (((UINT4)mdContext->in[ii+1]) << 8) |
+                ((UINT4)mdContext->in[ii]);
+      Transform (mdContext->buf, in);
+      mdi = 0;
+    }
+  }
+}
+
+/* The routine MD5Final terminates the message-digest computation and
+   ends with the desired message digest in mdContext->digest[0...15].
+ */
+
+void MD5Final (MD5_CTX *mdContext)
+{
+  UINT4 in[16];
+  int mdi;
+  unsigned int i, ii;
+  unsigned int padLen;
+
+  /* save number of bits */
+  in[14] = mdContext->i[0];
+  in[15] = mdContext->i[1];
+
+  /* compute number of bytes mod 64 */
+  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);
+
+  /* pad out to 56 mod 64 */
+  padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
+  MD5Update (mdContext, PADDING, padLen);
+
+  /* append length in bits and transform */
+  for (i = 0, ii = 0; i < 14; i++, ii += 4)
+    in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
+            (((UINT4)mdContext->in[ii+2]) << 16) |
+            (((UINT4)mdContext->in[ii+1]) << 8) |
+            ((UINT4)mdContext->in[ii]);
+  Transform (mdContext->buf, in);
+
+  /* store buffer in digest */
+  for (i = 0, ii = 0; i < 4; i++, ii += 4) {
+    mdContext->digest[ii] = (unsigned char)(mdContext->buf[i] & 0xFF);
+    mdContext->digest[ii+1] =
+      (unsigned char)((mdContext->buf[i] >> 8) & 0xFF);
+    mdContext->digest[ii+2] =
+      (unsigned char)((mdContext->buf[i] >> 16) & 0xFF);
+    mdContext->digest[ii+3] =
+      (unsigned char)((mdContext->buf[i] >> 24) & 0xFF);
+  }
+}
+
+/* Basic MD5 step. Transforms buf based on in.
+ */
+static void Transform (UINT4 *buf, UINT4 *in)
+{
+  UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
+
+  /* Round 1 */
+#define S11 7
+#define S12 12
+#define S13 17
+#define S14 22
+
+  FF ( a, b, c, d, in[ 0], S11, 0xd76aa478); /* 1 */
+  FF ( d, a, b, c, in[ 1], S12, 0xe8c7b756); /* 2 */
+  FF ( c, d, a, b, in[ 2], S13, 0x242070db); /* 3 */
+  FF ( b, c, d, a, in[ 3], S14, 0xc1bdceee); /* 4 */
+  FF ( a, b, c, d, in[ 4], S11, 0xf57c0faf); /* 5 */
+  FF ( d, a, b, c, in[ 5], S12, 0x4787c62a); /* 6 */
+  FF ( c, d, a, b, in[ 6], S13, 0xa8304613); /* 7 */
+  FF ( b, c, d, a, in[ 7], S14, 0xfd469501); /* 8 */
+  FF ( a, b, c, d, in[ 8], S11, 0x698098d8); /* 9 */
+  FF ( d, a, b, c, in[ 9], S12, 0x8b44f7af); /* 10 */
+  FF ( c, d, a, b, in[10], S13, 0xffff5bb1); /* 11 */
+  FF ( b, c, d, a, in[11], S14, 0x895cd7be); /* 12 */
+  FF ( a, b, c, d, in[12], S11, 0x6b901122); /* 13 */
+  FF ( d, a, b, c, in[13], S12, 0xfd987193); /* 14 */
+  FF ( c, d, a, b, in[14], S13, 0xa679438e); /* 15 */
+  FF ( b, c, d, a, in[15], S14, 0x49b40821); /* 16 */
+
+  /* Round 2 */
+#define S21 5
+#define S22 9
+#define S23 14
+#define S24 20
+  GG ( a, b, c, d, in[ 1], S21, 0xf61e2562); /* 17 */
+  GG ( d, a, b, c, in[ 6], S22, 0xc040b340); /* 18 */
+  GG ( c, d, a, b, in[11], S23, 0x265e5a51); /* 19 */
+  GG ( b, c, d, a, in[ 0], S24, 0xe9b6c7aa); /* 20 */
+  GG ( a, b, c, d, in[ 5], S21, 0xd62f105d); /* 21 */
+  GG ( d, a, b, c, in[10], S22,  0x2441453); /* 22 */
+  GG ( c, d, a, b, in[15], S23, 0xd8a1e681); /* 23 */
+  GG ( b, c, d, a, in[ 4], S24, 0xe7d3fbc8); /* 24 */
+  GG ( a, b, c, d, in[ 9], S21, 0x21e1cde6); /* 25 */
+  GG ( d, a, b, c, in[14], S22, 0xc33707d6); /* 26 */
+  GG ( c, d, a, b, in[ 3], S23, 0xf4d50d87); /* 27 */
+  GG ( b, c, d, a, in[ 8], S24, 0x455a14ed); /* 28 */
+  GG ( a, b, c, d, in[13], S21, 0xa9e3e905); /* 29 */
+  GG ( d, a, b, c, in[ 2], S22, 0xfcefa3f8); /* 30 */
+  GG ( c, d, a, b, in[ 7], S23, 0x676f02d9); /* 31 */
+  GG ( b, c, d, a, in[12], S24, 0x8d2a4c8a); /* 32 */
+
+  /* Round 3 */
+#define S31 4
+#define S32 11
+#define S33 16
+#define S34 23
+  HH ( a, b, c, d, in[ 5], S31, 0xfffa3942); /* 33 */
+  HH ( d, a, b, c, in[ 8], S32, 0x8771f681); /* 34 */
+  HH ( c, d, a, b, in[11], S33, 0x6d9d6122); /* 35 */
+  HH ( b, c, d, a, in[14], S34, 0xfde5380c); /* 36 */
+  HH ( a, b, c, d, in[ 1], S31, 0xa4beea44); /* 37 */
+  HH ( d, a, b, c, in[ 4], S32, 0x4bdecfa9); /* 38 */
+  HH ( c, d, a, b, in[ 7], S33, 0xf6bb4b60); /* 39 */
+  HH ( b, c, d, a, in[10], S34, 0xbebfbc70); /* 40 */
+  HH ( a, b, c, d, in[13], S31, 0x289b7ec6); /* 41 */
+  HH ( d, a, b, c, in[ 0], S32, 0xeaa127fa); /* 42 */
+  HH ( c, d, a, b, in[ 3], S33, 0xd4ef3085); /* 43 */
+  HH ( b, c, d, a, in[ 6], S34,  0x4881d05); /* 44 */
+  HH ( a, b, c, d, in[ 9], S31, 0xd9d4d039); /* 45 */
+  HH ( d, a, b, c, in[12], S32, 0xe6db99e5); /* 46 */
+  HH ( c, d, a, b, in[15], S33, 0x1fa27cf8); /* 47 */
+  HH ( b, c, d, a, in[ 2], S34, 0xc4ac5665); /* 48 */
+
+  /* Round 4 */
+#define S41 6
+#define S42 10
+#define S43 15
+#define S44 21
+  II ( a, b, c, d, in[ 0], S41, 0xf4292244); /* 49 */
+  II ( d, a, b, c, in[ 7], S42, 0x432aff97); /* 50 */
+  II ( c, d, a, b, in[14], S43, 0xab9423a7); /* 51 */
+  II ( b, c, d, a, in[ 5], S44, 0xfc93a039); /* 52 */
+  II ( a, b, c, d, in[12], S41, 0x655b59c3); /* 53 */
+  II ( d, a, b, c, in[ 3], S42, 0x8f0ccc92); /* 54 */
+  II ( c, d, a, b, in[10], S43, 0xffeff47d); /* 55 */
+  II ( b, c, d, a, in[ 1], S44, 0x85845dd1); /* 56 */
+  II ( a, b, c, d, in[ 8], S41, 0x6fa87e4f); /* 57 */
+  II ( d, a, b, c, in[15], S42, 0xfe2ce6e0); /* 58 */
+  II ( c, d, a, b, in[ 6], S43, 0xa3014314); /* 59 */
+  II ( b, c, d, a, in[13], S44, 0x4e0811a1); /* 60 */
+  II ( a, b, c, d, in[ 4], S41, 0xf7537e82); /* 61 */
+  II ( d, a, b, c, in[11], S42, 0xbd3af235); /* 62 */
+  II ( c, d, a, b, in[ 2], S43, 0x2ad7d2bb); /* 63 */
+  II ( b, c, d, a, in[ 9], S44, 0xeb86d391); /* 64 */
+
+  buf[0] += a;
+  buf[1] += b;
+  buf[2] += c;
+  buf[3] += d;
+}
+
+/*
+ ***********************************************************************
+ ** End of md5.c                                                      **
+ ******************************** (cut) ********************************
+ */
diff --git a/md5.h b/md5.h
new file mode 100644
index 0000000..5f37235
--- /dev/null
+++ b/md5.h
@@ -0,0 +1,56 @@
+/*
+ ***********************************************************************
+ ** md5.h -- header file for implementation of MD5                    **
+ ** RSA Data Security, Inc. MD5 Message-Digest Algorithm              **
+ ** Created: 2/17/90 RLR                                              **
+ ** Revised: 12/27/90 SRD,AJ,BSK,JT Reference C version               **
+ ** Revised (for MD5): RLR 4/27/91                                    **
+ ***********************************************************************
+ */
+
+/*
+ ***********************************************************************
+ ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
+ **                                                                   **
+ ** License to copy and use this software is granted provided that    **
+ ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
+ ** Digest Algorithm" in all material mentioning or referencing this  **
+ ** software or this function.                                        **
+ **                                                                   **
+ ** License is also granted to make and use derivative works          **
+ ** provided that such works are identified as "derived from the RSA  **
+ ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
+ ** material mentioning or referencing the derived work.              **
+ **                                                                   **
+ ** RSA Data Security, Inc. makes no representations concerning       **
+ ** either the merchantability of this software or the suitability    **
+ ** of this software for any particular purpose.  It is provided "as  **
+ ** is" without express or implied warranty of any kind.              **
+ **                                                                   **
+ ** These notices must be retained in any copies of any part of this  **
+ ** documentation and/or software.                                    **
+ ***********************************************************************
+ */
+
+#include "sysincl.h"
+
+/* typedef a 32-bit type */
+typedef uint32_t UINT4;
+
+/* Data structure for MD5 (Message-Digest) computation */
+typedef struct {
+  UINT4 i[2];                   /* number of _bits_ handled mod 2^64 */
+  UINT4 buf[4];                                    /* scratch buffer */
+  unsigned char in[64];                              /* input buffer */
+  unsigned char digest[16];     /* actual digest after MD5Final call */
+} MD5_CTX;
+
+void MD5Init (MD5_CTX *mdContext);
+void MD5Update (MD5_CTX *, unsigned const char *, unsigned int);
+void MD5Final (MD5_CTX *);
+
+/*
+ ***********************************************************************
+ ** End of md5.h                                                      **
+ ******************************** (cut) ********************************
+ */
diff --git a/memory.c b/memory.c
new file mode 100644
index 0000000..25a484d
--- /dev/null
+++ b/memory.c
@@ -0,0 +1,98 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014, 2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Utility functions for memory allocation.
+
+  */
+
+#include "config.h"
+
+#include "logging.h"
+#include "memory.h"
+
+void *
+Malloc(size_t size)
+{
+  void *r;
+
+  r = malloc(size);
+  if (!r && size)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
+
+void *
+Realloc(void *ptr, size_t size)
+{
+  void *r;
+
+  if (size == 0) {
+    Free(ptr);
+    return NULL;
+  }
+
+  r = realloc(ptr, size);
+  if (!r)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
+
+static size_t
+get_array_size(size_t nmemb, size_t size)
+{
+  size_t array_size;
+
+  array_size = nmemb * size;
+
+  /* Check for overflow */
+  if (nmemb > 0 && array_size / nmemb != size)
+    LOG_FATAL("Could not allocate memory");
+
+  return array_size;
+}
+
+void *
+Malloc2(size_t nmemb, size_t size)
+{
+  return Malloc(get_array_size(nmemb, size));
+}
+
+void *
+Realloc2(void *ptr, size_t nmemb, size_t size)
+{
+  return Realloc(ptr, get_array_size(nmemb, size));
+}
+
+char *
+Strdup(const char *s)
+{
+  void *r;
+
+  r = strdup(s);
+  if (!r)
+    LOG_FATAL("Could not allocate memory");
+
+  return r;
+}
diff --git a/memory.h b/memory.h
new file mode 100644
index 0000000..7ae2c03
--- /dev/null
+++ b/memory.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for memory functions
+  */
+
+#ifndef GOT_MEMORY_H
+#define GOT_MEMORY_H
+
+#include "sysincl.h"
+
+/* Wrappers checking for errors */
+extern void *Malloc(size_t size);
+extern void *Realloc(void *ptr, size_t size);
+extern void *Malloc2(size_t nmemb, size_t size);
+extern void *Realloc2(void *ptr, size_t nmemb, size_t size);
+extern char *Strdup(const char *s);
+
+/* Convenient macros */
+#define MallocNew(T) ((T *) Malloc(sizeof(T)))
+#define MallocArray(T, n) ((T *) Malloc2(n, sizeof(T)))
+#define ReallocArray(T, n, x) ((T *) Realloc2((void *)(x), n, sizeof(T)))
+#define Free(x) free(x)
+
+#endif /* GOT_MEMORY_H */
diff --git a/nameserv.c b/nameserv.c
new file mode 100644
index 0000000..9f7e648
--- /dev/null
+++ b/nameserv.c
@@ -0,0 +1,166 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2011
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions to do name to IP address conversion
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <netdb.h>
+#include <resolv.h>
+
+#include "nameserv.h"
+#include "socket.h"
+#include "util.h"
+
+/* ================================================== */
+
+static int address_family = IPADDR_UNSPEC;
+
+void
+DNS_SetAddressFamily(int family)
+{
+  address_family = family;
+}
+
+DNS_Status 
+DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  struct addrinfo hints, *res, *ai;
+  int i, result;
+  IPAddr ip;
+
+  max_addrs = MIN(max_addrs, DNS_MAX_ADDRESSES);
+
+  for (i = 0; i < max_addrs; i++)
+    ip_addrs[i].family = IPADDR_UNSPEC;
+
+  /* Avoid calling getaddrinfo() if the name is an IP address */
+  if (UTI_StringToIP(name, &ip)) {
+    if (address_family != IPADDR_UNSPEC && ip.family != address_family)
+      return DNS_Failure;
+    if (max_addrs >= 1)
+      ip_addrs[0] = ip;
+    return DNS_Success;
+  }
+
+  memset(&hints, 0, sizeof (hints));
+
+  switch (address_family) {
+    case IPADDR_INET4:
+      hints.ai_family = AF_INET;
+      break;
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      hints.ai_family = AF_INET6;
+      break;
+#endif
+    default:
+      hints.ai_family = AF_UNSPEC;
+  }
+  hints.ai_socktype = SOCK_DGRAM;
+
+  result = getaddrinfo(name, NULL, &hints, &res);
+
+  if (result) {
+#ifdef FORCE_DNSRETRY
+    return DNS_TryAgain;
+#else
+    return result == EAI_AGAIN ? DNS_TryAgain : DNS_Failure;
+#endif
+  }
+
+  for (ai = res, i = 0; i < max_addrs && ai != NULL; ai = ai->ai_next) {
+    switch (ai->ai_family) {
+      case AF_INET:
+        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET4)
+          continue;
+        ip_addrs[i].family = IPADDR_INET4;
+        ip_addrs[i].addr.in4 = ntohl(((struct sockaddr_in *)ai->ai_addr)->sin_addr.s_addr);
+        i++;
+        break;
+#ifdef FEAT_IPV6
+      case AF_INET6:
+        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET6)
+          continue;
+        /* Don't return an address that would lose a scope ID */
+        if (((struct sockaddr_in6 *)ai->ai_addr)->sin6_scope_id != 0)
+          continue;
+        ip_addrs[i].family = IPADDR_INET6;
+        memcpy(&ip_addrs[i].addr.in6, &((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr.s6_addr,
+               sizeof (ip_addrs->addr.in6));
+        i++;
+        break;
+#endif
+    }
+  }
+
+  freeaddrinfo(res);
+
+  return !max_addrs || ip_addrs[0].family != IPADDR_UNSPEC ? DNS_Success : DNS_Failure;
+}
+
+/* ================================================== */
+
+int
+DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len)
+{
+  char *result = NULL;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 saddr;
+#else
+  struct sockaddr_in saddr;
+#endif
+  IPSockAddr ip_saddr;
+  socklen_t slen;
+  char hbuf[NI_MAXHOST];
+
+  ip_saddr.ip_addr = *ip_addr;
+  ip_saddr.port = 0;
+
+  slen = SCK_IPSockAddrToSockaddr(&ip_saddr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (!getnameinfo((struct sockaddr *)&saddr, slen, hbuf, sizeof (hbuf), NULL, 0, 0))
+    result = hbuf;
+
+  if (result == NULL)
+    result = UTI_IPToString(ip_addr);
+  if (snprintf(name, len, "%s", result) >= len)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+DNS_Reload(void)
+{
+  res_init();
+}
+
+/* ================================================== */
+
diff --git a/nameserv.h b/nameserv.h
new file mode 100644
index 0000000..dbef61a
--- /dev/null
+++ b/nameserv.h
@@ -0,0 +1,52 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Module header for nameserver functions
+  */
+
+
+#ifndef GOT_NAMESERV_H
+#define GOT_NAMESERV_H
+
+#include "addressing.h"
+
+typedef enum {
+  DNS_Success,
+  DNS_TryAgain,
+  DNS_Failure
+} DNS_Status;
+
+/* Resolve names only to selected address family */
+extern void DNS_SetAddressFamily(int family);
+
+/* Maximum number of addresses returned by DNS_Name2IPAddress */
+#define DNS_MAX_ADDRESSES 16
+
+extern DNS_Status DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs);
+
+extern int DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len);
+
+extern void DNS_Reload(void);
+
+#endif /* GOT_NAMESERV_H */
+
diff --git a/nameserv_async.c b/nameserv_async.c
new file mode 100644
index 0000000..118443c
--- /dev/null
+++ b/nameserv_async.c
@@ -0,0 +1,130 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions to asynchronously convert name to IP address
+
+  */
+
+#include "config.h"
+#include "sysincl.h"
+
+#include "nameserv_async.h"
+#include "logging.h"
+#include "memory.h"
+#include "privops.h"
+#include "sched.h"
+#include "util.h"
+
+#ifdef USE_PTHREAD_ASYNCDNS
+#include <pthread.h>
+
+/* ================================================== */
+
+struct DNS_Async_Instance {
+  const char *name;
+  DNS_Status status;
+  IPAddr addresses[DNS_MAX_ADDRESSES];
+  DNS_NameResolveHandler handler;
+  void *arg;
+
+  pthread_t thread;
+  int pipe[2];
+};
+
+static pthread_mutex_t privops_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/* ================================================== */
+
+static void *
+start_resolving(void *anything)
+{
+  struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
+
+  pthread_mutex_lock(&privops_lock);
+  inst->status = PRV_Name2IPAddress(inst->name, inst->addresses, DNS_MAX_ADDRESSES);
+  pthread_mutex_unlock(&privops_lock);
+
+  /* Notify the main thread that the result is ready */
+  if (write(inst->pipe[1], "", 1) < 0)
+    ;
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+end_resolving(int fd, int event, void *anything)
+{
+  struct DNS_Async_Instance *inst = (struct DNS_Async_Instance *)anything;
+  int i;
+
+  if (pthread_join(inst->thread, NULL)) {
+    LOG_FATAL("pthread_join() failed");
+  }
+
+  SCH_RemoveFileHandler(inst->pipe[0]);
+  close(inst->pipe[0]);
+  close(inst->pipe[1]);
+
+  for (i = 0; inst->status == DNS_Success && i < DNS_MAX_ADDRESSES &&
+              inst->addresses[i].family != IPADDR_UNSPEC; i++)
+    ;
+
+  (inst->handler)(inst->status, i, inst->addresses, inst->arg);
+
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+
+  inst = MallocNew(struct DNS_Async_Instance);
+  inst->name = name;
+  inst->handler = handler;
+  inst->arg = anything;
+  inst->status = DNS_Failure;
+
+  if (pipe(inst->pipe)) {
+    LOG_FATAL("pipe() failed");
+  }
+
+  UTI_FdSetCloexec(inst->pipe[0]);
+  UTI_FdSetCloexec(inst->pipe[1]);
+
+  if (pthread_create(&inst->thread, NULL, start_resolving, inst)) {
+    LOG_FATAL("pthread_create() failed");
+  }
+
+  SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, end_resolving, inst);
+}
+
+/* ================================================== */
+
+#else
+#error
+#endif
diff --git a/nameserv_async.h b/nameserv_async.h
new file mode 100644
index 0000000..b8479e1
--- /dev/null
+++ b/nameserv_async.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for asynchronous nameserver functions
+  */
+
+
+#ifndef GOT_NAMESERV_ASYNC_H
+#define GOT_NAMESERV_ASYNC_H
+
+#include "nameserv.h"
+
+/* Function type for callback to process the result */
+typedef void (*DNS_NameResolveHandler)(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *anything);
+
+/* Request resolving of a name to IP address. The handler will be
+   called when the result is available. */
+extern void DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything);
+
+#endif
diff --git a/ntp.h b/ntp.h
new file mode 100644
index 0000000..906adc3
--- /dev/null
+++ b/ntp.h
@@ -0,0 +1,189 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file containing common NTP bits and pieces
+  */
+
+#ifndef GOT_NTP_H
+#define GOT_NTP_H
+
+#include "sysincl.h"
+
+#include "hash.h"
+
+typedef struct {
+  uint32_t hi;
+  uint32_t lo;
+} NTP_int64;
+
+typedef uint32_t NTP_int32;
+
+/* The UDP port number used by NTP */
+#define NTP_PORT 123
+
+/* The NTP protocol version that we support */
+#define NTP_VERSION 4
+
+/* Maximum stratum number (infinity) */
+#define NTP_MAX_STRATUM 16
+
+/* Invalid stratum number */
+#define NTP_INVALID_STRATUM 0
+
+/* The minimum and maximum supported length of MAC */
+#define NTP_MIN_MAC_LENGTH (4 + 16)
+#define NTP_MAX_MAC_LENGTH (4 + MAX_HASH_LENGTH)
+
+/* The minimum valid length of an extension field */
+#define NTP_MIN_EF_LENGTH 16
+
+/* The maximum assumed length of all extension fields in an NTP packet,
+   including a MAC (RFC 5905 doesn't specify a limit on length or number of
+   extension fields in one packet) */
+#define NTP_MAX_EXTENSIONS_LENGTH (1024 + NTP_MAX_MAC_LENGTH)
+
+/* The maximum length of MAC in NTPv4 packets which allows deterministic
+   parsing of extension fields (RFC 7822) */
+#define NTP_MAX_V4_MAC_LENGTH (4 + 20)
+
+/* Type definition for leap bits */
+typedef enum {
+  LEAP_Normal = 0,
+  LEAP_InsertSecond = 1,
+  LEAP_DeleteSecond = 2,
+  LEAP_Unsynchronised = 3
+} NTP_Leap;
+
+typedef enum {
+  MODE_UNDEFINED = 0,
+  MODE_ACTIVE = 1,
+  MODE_PASSIVE = 2,
+  MODE_CLIENT = 3,
+  MODE_SERVER = 4,
+  MODE_BROADCAST = 5
+} NTP_Mode;
+
+typedef struct {
+  uint8_t lvm;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  NTP_int32 root_delay;
+  NTP_int32 root_dispersion;
+  NTP_int32 reference_id;
+  NTP_int64 reference_ts;
+  NTP_int64 originate_ts;
+  NTP_int64 receive_ts;
+  NTP_int64 transmit_ts;
+
+  uint8_t extensions[NTP_MAX_EXTENSIONS_LENGTH];
+} NTP_Packet;
+
+#define NTP_HEADER_LENGTH (int)offsetof(NTP_Packet, extensions)
+
+/* Macros to work with the lvm field */
+#define NTP_LVM_TO_LEAP(lvm) (((lvm) >> 6) & 0x3)
+#define NTP_LVM_TO_VERSION(lvm) (((lvm) >> 3) & 0x7)
+#define NTP_LVM_TO_MODE(lvm) ((lvm) & 0x7)
+#define NTP_LVM(leap, version, mode) \
+  ((((leap) << 6) & 0xc0) | (((version) << 3) & 0x38) | ((mode) & 0x07))
+
+/* Special NTP reference IDs */
+#define NTP_REFID_UNSYNC 0x0UL
+#define NTP_REFID_LOCAL 0x7F7F0101UL /* 127.127.1.1 */
+#define NTP_REFID_SMOOTH 0x7F7F01FFUL /* 127.127.1.255 */
+
+/* Non-authentication extension fields and corresponding internal flags */
+
+#define NTP_EF_EXP1                     0xF323
+
+#define NTP_EF_FLAG_EXP1                0x1
+
+/* Pre-NTPv5 experimental extension field */
+typedef struct {
+  uint32_t magic;
+  NTP_int32 root_delay;
+  NTP_int32 root_dispersion;
+  NTP_int64 mono_receive_ts;
+  uint32_t mono_epoch;
+} NTP_ExtFieldExp1;
+
+#define NTP_EF_EXP1_MAGIC 0xF5BEDD9AU
+
+/* Authentication extension fields */
+
+#define NTP_EF_NTS_UNIQUE_IDENTIFIER    0x0104
+#define NTP_EF_NTS_COOKIE               0x0204
+#define NTP_EF_NTS_COOKIE_PLACEHOLDER   0x0304
+#define NTP_EF_NTS_AUTH_AND_EEF         0x0404
+
+/* Enumeration for authentication modes of NTP packets */
+typedef enum {
+  NTP_AUTH_NONE = 0,            /* No authentication */
+  NTP_AUTH_SYMMETRIC,           /* NTP MAC or CMAC using a symmetric key
+                                   (RFC 1305, RFC 5905, RFC 8573) */
+  NTP_AUTH_MSSNTP,              /* MS-SNTP authenticator field */
+  NTP_AUTH_MSSNTP_EXT,          /* MS-SNTP extended authenticator field */
+  NTP_AUTH_NTS,                 /* Network Time Security (RFC 8915) */
+} NTP_AuthMode;
+
+/* Structure describing an NTP packet */
+typedef struct {
+  int length;
+  int version;
+  NTP_Mode mode;
+
+  int ext_fields;
+  int ext_field_flags;
+
+  struct {
+    NTP_AuthMode mode;
+    struct {
+      int start;
+      int length;
+      uint32_t key_id;
+    } mac;
+  } auth;
+} NTP_PacketInfo;
+
+/* Structure used to save NTP measurements.  time is the local time at which
+   the sample is to be considered to have been made and offset is the offset at
+   the time (positive indicates that the local clock is slow relative to the
+   source).  root_delay/root_dispersion include peer_delay/peer_dispersion. */
+typedef struct {
+  struct timespec time;
+  double offset;
+  double peer_delay;
+  double peer_dispersion;
+  double root_delay;
+  double root_dispersion;
+} NTP_Sample;
+
+/* Possible sources of timestamps */
+typedef enum {
+  NTP_TS_DAEMON = 0,
+  NTP_TS_KERNEL,
+  NTP_TS_HARDWARE
+} NTP_Timestamp_Source;
+
+#endif /* GOT_NTP_H */
diff --git a/ntp_auth.c b/ntp_auth.c
new file mode 100644
index 0000000..58374c5
--- /dev/null
+++ b/ntp_auth.c
@@ -0,0 +1,386 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "keys.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp_auth.h"
+#include "ntp_signd.h"
+#include "nts_ntp.h"
+#include "nts_ntp_client.h"
+#include "nts_ntp_server.h"
+#include "srcparams.h"
+#include "util.h"
+
+/* Structure to hold authentication configuration and state */
+
+struct NAU_Instance_Record {
+  NTP_AuthMode mode;            /* Authentication mode of NTP packets */
+  uint32_t key_id;              /* Identifier of a symmetric key */
+  NNC_Instance nts;             /* Client NTS state */
+};
+
+/* ================================================== */
+
+static int
+generate_symmetric_auth(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  int auth_len, max_auth_len;
+
+  if (info->length + NTP_MIN_MAC_LENGTH > sizeof (*packet)) {
+    DEBUG_LOG("Packet too long");
+    return 0;
+  }
+
+  /* Truncate long MACs in NTPv4 packets to allow deterministic parsing
+     of extension fields (RFC 7822) */
+  max_auth_len = (info->version == 4 ? NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH) - 4;
+  max_auth_len = MIN(max_auth_len, sizeof (*packet) - info->length - 4);
+
+  auth_len = KEY_GenerateAuth(key_id, packet, info->length,
+                              (unsigned char *)packet + info->length + 4, max_auth_len);
+  if (auth_len < NTP_MIN_MAC_LENGTH - 4) {
+    DEBUG_LOG("Could not generate auth data with key %"PRIu32, key_id);
+    return 0;
+  }
+
+  *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+
+  info->auth.mac.start = info->length;
+  info->auth.mac.length = 4 + auth_len;
+  info->auth.mac.key_id = key_id;
+  info->length += info->auth.mac.length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+check_symmetric_auth(NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  int trunc_len;
+
+  if (info->auth.mac.length < NTP_MIN_MAC_LENGTH)
+    return 0;
+
+  trunc_len = info->version == 4 && info->auth.mac.length <= NTP_MAX_V4_MAC_LENGTH ?
+              NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH;
+
+  if (!KEY_CheckAuth(info->auth.mac.key_id, packet, info->auth.mac.start,
+                     (unsigned char *)packet + info->auth.mac.start + 4,
+                     info->auth.mac.length - 4, trunc_len - 4))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static NAU_Instance
+create_instance(NTP_AuthMode mode)
+{
+  NAU_Instance instance;
+
+  instance = MallocNew(struct NAU_Instance_Record);
+  instance->mode = mode;
+  instance->key_id = INACTIVE_AUTHKEY;
+  instance->nts = NULL;
+
+  assert(sizeof (instance->key_id) == 4);
+
+  return instance;
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateNoneInstance(void)
+{
+  return create_instance(NTP_AUTH_NONE);
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateSymmetricInstance(uint32_t key_id)
+{
+  NAU_Instance instance = create_instance(NTP_AUTH_SYMMETRIC);
+
+  instance->key_id = key_id;
+
+  if (!KEY_KeyKnown(key_id))
+    LOG(LOGS_WARN, "Key %"PRIu32" is %s", key_id, "missing");
+  else if (!KEY_CheckKeyLength(key_id))
+    LOG(LOGS_WARN, "Key %"PRIu32" is %s", key_id, "too short");
+
+  return instance;
+}
+
+/* ================================================== */
+
+NAU_Instance
+NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set,
+                      uint16_t ntp_port)
+{
+  NAU_Instance instance = create_instance(NTP_AUTH_NTS);
+
+  instance->nts = NNC_CreateInstance(nts_address, name, cert_set, ntp_port);
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+NAU_DestroyInstance(NAU_Instance instance)
+{
+  if (instance->mode == NTP_AUTH_NTS)
+    NNC_DestroyInstance(instance->nts);
+  Free(instance);
+}
+
+/* ================================================== */
+
+int
+NAU_IsAuthEnabled(NAU_Instance instance)
+{
+  return instance->mode != NTP_AUTH_NONE;
+}
+
+/* ================================================== */
+
+int
+NAU_GetSuggestedNtpVersion(NAU_Instance instance)
+{
+  /* If the MAC in NTPv4 packets would be truncated, prefer NTPv3 for
+     compatibility with older chronyd servers */
+  if (instance->mode == NTP_AUTH_SYMMETRIC &&
+      KEY_GetAuthLength(instance->key_id) + sizeof (instance->key_id) > NTP_MAX_V4_MAC_LENGTH)
+    return 3;
+
+  return NTP_VERSION;
+}
+
+/* ================================================== */
+
+int
+NAU_PrepareRequestAuth(NAU_Instance instance)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NTS:
+      if (!NNC_PrepareForAuth(instance->nts))
+        return 0;
+      break;
+    default:
+      break;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request, NTP_PacketInfo *info)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!generate_symmetric_auth(instance->key_id, request, info))
+        return 0;
+      break;
+    case NTP_AUTH_NTS:
+      if (!NNC_GenerateRequestAuth(instance->nts, request, info))
+        return 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  info->auth.mode = instance->mode;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod)
+{
+  *kod = 0;
+
+  switch (info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!check_symmetric_auth(request, info))
+        return 0;
+      break;
+    case NTP_AUTH_MSSNTP:
+      /* MS-SNTP requests are not authenticated */
+      break;
+    case NTP_AUTH_MSSNTP_EXT:
+      /* Not supported yet */
+      return 0;
+    case NTP_AUTH_NTS:
+      if (!NNS_CheckRequestAuth(request, info, kod))
+        return 0;
+      break;
+    default:
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
+                         NTP_Packet *response, NTP_PacketInfo *response_info,
+                         NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                         uint32_t kod)
+{
+  switch (request_info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      if (!generate_symmetric_auth(request_info->auth.mac.key_id, response, response_info))
+        return 0;
+      break;
+    case NTP_AUTH_MSSNTP:
+      /* Sign the packet asynchronously by ntp_signd */
+      if (!NSD_SignAndSendPacket(request_info->auth.mac.key_id, response, response_info,
+                                 remote_addr, local_addr))
+        return 0;
+      /* Don't send the original packet */
+      return 0;
+    case NTP_AUTH_NTS:
+      if (!NNS_GenerateResponseAuth(request, request_info, response, response_info, kod))
+        return 0;
+      break;
+    default:
+      DEBUG_LOG("Could not authenticate response auth_mode=%d", (int)request_info->auth.mode);
+      return 0;
+  }
+
+  response_info->auth.mode = request_info->auth.mode;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response, NTP_PacketInfo *info)
+{
+  /* The authentication must match the expected mode */
+  if (info->auth.mode != instance->mode)
+    return 0;
+
+  switch (info->auth.mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      /* Check if it is authenticated with the specified key */
+      if (info->auth.mac.key_id != instance->key_id)
+        return 0;
+      /* and that the MAC is valid */
+      if (!check_symmetric_auth(response, info))
+        return 0;
+      break;
+    case NTP_AUTH_NTS:
+      if (!NNC_CheckResponseAuth(instance->nts, response, info))
+        return 0;
+      break;
+    default:
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NAU_ChangeAddress(NAU_Instance instance, IPAddr *address)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+    case NTP_AUTH_SYMMETRIC:
+      break;
+    case NTP_AUTH_NTS:
+      NNC_ChangeAddress(instance->nts, address);
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NAU_DumpData(NAU_Instance instance)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NTS:
+      NNC_DumpData(instance->nts);
+      break;
+    default:
+      break;
+  }
+}
+
+/* ================================================== */
+
+void
+NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report)
+{
+  memset(report, 0, sizeof (*report));
+
+  report->mode = instance->mode;
+  report->last_ke_ago = -1;
+
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      report->key_id = instance->key_id;
+      KEY_GetKeyInfo(instance->key_id, &report->key_type, &report->key_length);
+      break;
+    case NTP_AUTH_NTS:
+      NNC_GetReport(instance->nts, report);
+      break;
+    default:
+      assert(0);
+  }
+}
diff --git a/ntp_auth.h b/ntp_auth.h
new file mode 100644
index 0000000..0b8a825
--- /dev/null
+++ b/ntp_auth.h
@@ -0,0 +1,84 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NTP authentication
+  */
+
+#ifndef GOT_NTP_AUTH_H
+#define GOT_NTP_AUTH_H
+
+#include "addressing.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef struct NAU_Instance_Record *NAU_Instance;
+
+/* Create an authenticator instance in a specific mode */
+extern NAU_Instance NAU_CreateNoneInstance(void);
+extern NAU_Instance NAU_CreateSymmetricInstance(uint32_t key_id);
+extern NAU_Instance NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name,
+                                          uint32_t cert_set, uint16_t ntp_port);
+
+/* Destroy an instance */
+extern void NAU_DestroyInstance(NAU_Instance instance);
+
+/* Check if an instance is not in the None mode */
+extern int NAU_IsAuthEnabled(NAU_Instance instance);
+
+/* Get NTP version recommended for better compatibility */
+extern int NAU_GetSuggestedNtpVersion(NAU_Instance instance);
+
+/* Perform operations necessary for NAU_GenerateRequestAuth() */
+extern int NAU_PrepareRequestAuth(NAU_Instance instance);
+
+/* Extend a request with data required by the authentication mode */
+extern int NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request,
+                                   NTP_PacketInfo *info);
+
+/* Verify that a request is authentic.  If it is not authentic and a non-zero
+   kod code is returned, a KoD response should be sent back. */
+extern int NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod);
+
+/* Extend a response with data required by the authentication mode.  This
+   function can be called only if the previous call of NAU_CheckRequestAuth()
+   was on the same request. */
+extern int NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
+                                    NTP_Packet *response, NTP_PacketInfo *response_info,
+                                    NTP_Remote_Address *remote_addr,
+                                    NTP_Local_Address *local_addr,
+                                    uint32_t kod);
+
+/* Verify that a response is authentic */
+extern int NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response,
+                                 NTP_PacketInfo *info);
+
+/* Change an authentication-specific address (e.g. after replacing a source) */
+extern void NAU_ChangeAddress(NAU_Instance instance, IPAddr *address);
+
+/* Save authentication-specific data to speed up the next start */
+extern void NAU_DumpData(NAU_Instance instance);
+
+/* Provide a report about the current authentication state */
+extern void NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report);
+
+#endif
diff --git a/ntp_core.c b/ntp_core.c
new file mode 100644
index 0000000..22cab43
--- /dev/null
+++ b/ntp_core.c
@@ -0,0 +1,3142 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Core NTP protocol engine
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "ntp_auth.h"
+#include "ntp_core.h"
+#include "ntp_ext.h"
+#include "ntp_io.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "sched.h"
+#include "reference.h"
+#include "local.h"
+#include "samplefilt.h"
+#include "smooth.h"
+#include "sources.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "addrfilt.h"
+#include "clientlog.h"
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+static int log_raw_measurements;
+
+/* ================================================== */
+/* Enumeration used for remembering the operating mode of one of the
+   sources */
+
+typedef enum {
+  MD_OFFLINE,                   /* No sampling at all */
+  MD_ONLINE,                    /* Normal sampling based on sampling interval */
+  MD_BURST_WAS_OFFLINE,         /* Burst sampling, return to offline afterwards */
+  MD_BURST_WAS_ONLINE,          /* Burst sampling, return to online afterwards */
+} OperatingMode;
+
+/* Structure holding a response and other data waiting to be processed when
+   a late HW transmit timestamp of the request is available, or a timeout is
+   reached */
+struct SavedResponse {
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp rx_ts;
+  NTP_Packet message;
+  NTP_PacketInfo info;
+  SCH_TimeoutID timeout_id;
+};
+
+/* ================================================== */
+/* Structure used for holding a single peer/server's
+   protocol machine */
+
+struct NCR_Instance_Record {
+  NTP_Remote_Address remote_addr; /* Needed for routing transmit packets */
+  NTP_Local_Address local_addr; /* Local address/socket used to send packets */
+  NTP_Mode mode;                /* The source's NTP mode
+                                   (client/server or symmetric active peer) */
+  int interleaved;              /* Boolean enabling interleaved NTP mode */
+  OperatingMode opmode;         /* Whether we are sampling this source
+                                   or not and in what way */
+  SCH_TimeoutID rx_timeout_id;  /* Timeout ID for latest received response */
+  SCH_TimeoutID tx_timeout_id;  /* Timeout ID for next transmission */
+  int tx_suspended;             /* Boolean indicating we can't transmit yet */
+
+  int auto_iburst;              /* If 1, initiate a burst when going online */
+  int auto_burst;               /* If 1, initiate a burst on each poll */
+  int auto_offline;             /* If 1, automatically go offline when requests
+                                   cannot be sent */
+
+  int local_poll;               /* Log2 of polling interval at our end */
+  int remote_poll;              /* Log2 of server/peer's polling interval (recovered
+                                   from received packets) */
+  int remote_stratum;           /* Stratum of the server/peer (recovered from
+                                   received packets) */
+  double remote_root_delay;     /* Root delay from last valid packet */
+  double remote_root_dispersion;/* Root dispersion from last valid packet */
+
+  int presend_minpoll;           /* If the current polling interval is
+                                    at least this, an extra client packet
+                                    will be send some time before normal
+                                    transmit.  This ensures that both
+                                    us and the server/peer have an ARP
+                                    entry for each other ready, which
+                                    means our measurement is not
+                                    botched by an ARP round-trip on one
+                                    side or the other. */
+
+  int presend_done;             /* The presend packet has been sent */
+
+  int minpoll;                  /* Log2 of minimum defined polling interval */
+  int maxpoll;                  /* Log2 of maximum defined polling interval */
+
+  int min_stratum;              /* Increase stratum in received packets to the
+                                   minimum */
+
+  int copy;                     /* Boolean suppressing own refid and stratum */
+
+  int poll_target;              /* Target number of sourcestats samples */
+
+  int version;                  /* Version set in packets for server/peer */
+
+  double poll_score;            /* Score of current local poll */
+
+  double max_delay;             /* Maximum round-trip delay to the
+                                   peer that we can tolerate and still
+                                   use the sample for generating
+                                   statistics from */
+
+  double max_delay_ratio;       /* Largest ratio of delay /
+                                   min_delay_in_register that we can
+                                   tolerate.  */
+
+  double max_delay_dev_ratio;   /* Maximum ratio of increase in delay / stddev */
+
+  double offset_correction;     /* Correction applied to measured offset
+                                   (e.g. for asymmetry in network delay) */
+
+  int ext_field_flags;          /* Enabled extension fields */
+
+  uint32_t remote_mono_epoch;   /* ID of the source's monotonic scale */
+  double mono_doffset;          /* Accumulated offset between source's
+                                   real-time and monotonic scales */
+
+  NAU_Instance auth;            /* Authentication */
+
+  /* Count of transmitted packets since last valid response */
+  unsigned int tx_count;
+
+  /* Flag indicating a valid response was received since last request */
+  int valid_rx;
+
+  /* Flag indicating the timestamps below are from a valid packet and may
+     be used for synchronisation */
+  int valid_timestamps;
+
+  /* Receive and transmit timestamps from the last valid response */
+  NTP_int64 remote_ntp_monorx;
+  NTP_int64 remote_ntp_rx;
+  NTP_int64 remote_ntp_tx;
+
+  /* Local timestamp when the last valid response was received from the
+     source.  We have to be prepared to tinker with this if the local
+     clock has its frequency adjusted before we repond.  The value we
+     store here is what our own local time was when the same arrived.
+     Before replying, we have to correct this to fit with the
+     parameters for the current reference.  (It must be stored
+     relative to local time to permit frequency and offset adjustments
+     to be made when we trim the local clock). */
+  NTP_int64 local_ntp_rx;
+  NTP_Local_Timestamp local_rx;
+
+  /* Local timestamp when we last transmitted a packet to the source.
+     We store two versions.  The first is in NTP format, and is used
+     to validate the next received packet from the source.
+     Additionally, this is corrected to bring it into line with the
+     current reference.  The second is in timespec format, and is kept
+     relative to the local clock.  We modify this in accordance with
+     local clock frequency/offset changes, and use this for computing
+     statistics about the source when a return packet arrives. */
+  NTP_int64 local_ntp_tx;
+  NTP_Local_Timestamp local_tx;
+
+  /* Previous values of some variables needed in interleaved mode */
+  NTP_Local_Timestamp prev_local_tx;
+  int prev_local_poll;
+  unsigned int prev_tx_count;
+
+  /* Flag indicating the two timestamps below were updated since the
+     last transmission */
+  int updated_init_timestamps;
+
+  /* Timestamps used for (re)starting the symmetric protocol, when we
+     need to respond to a packet which is not a valid response */
+  NTP_int64 init_remote_ntp_tx;
+  NTP_Local_Timestamp init_local_rx;
+
+  /* The instance record in the main source management module.  This
+     performs the statistical analysis on the samples we generate */
+
+  SRC_Instance source;
+
+  /* Optional long-term quantile estimate of peer delay */
+  QNT_Instance delay_quant;
+
+  /* Optional median filter for NTP measurements */
+  SPF_Instance filter;
+  int filter_count;
+
+  /* Response waiting for a HW transmit timestamp of the request */
+  struct SavedResponse *saved_response;
+
+  int burst_good_samples_to_go;
+  int burst_total_samples_to_go;
+
+  /* Report from last valid response */
+  RPT_NTPReport report;
+};
+
+typedef struct {
+  NTP_Remote_Address addr;
+  NTP_Local_Address local_addr;
+  NAU_Instance auth;
+  int interval;
+} BroadcastDestination;
+
+/* Array of BroadcastDestination */
+static ARR_Instance broadcasts;
+
+/* ================================================== */
+/* Initial delay period before first packet is transmitted (in seconds) */
+#define INITIAL_DELAY 0.2
+
+/* Spacing required between samples for any two servers/peers (to
+   minimise risk of network collisions) (in seconds) */
+#define MIN_SAMPLING_SEPARATION 0.002
+#define MAX_SAMPLING_SEPARATION 0.2
+
+/* Randomness added to spacing between samples for one server/peer */
+#define SAMPLING_RANDOMNESS 0.02
+
+/* Adjustment of the peer polling interval */
+#define PEER_SAMPLING_ADJ 1.1
+
+/* Maximum spacing between samples in the burst mode as an absolute
+   value and ratio to the normal polling interval */
+#define MAX_BURST_INTERVAL 2.0
+#define MAX_BURST_POLL_RATIO 0.25
+
+/* Number of samples in initial burst */
+#define IBURST_GOOD_SAMPLES 4
+#define IBURST_TOTAL_SAMPLES SOURCE_REACH_BITS
+
+/* Number of samples in automatic burst */
+#define BURST_GOOD_SAMPLES 1
+#define MAX_BURST_TOTAL_SAMPLES 4
+
+/* Time to wait after sending packet to 'warm up' link */
+#define WARM_UP_DELAY 2.0
+
+/* Compatible NTP protocol versions */
+#define NTP_MAX_COMPAT_VERSION NTP_VERSION
+#define NTP_MIN_COMPAT_VERSION 1
+
+/* Maximum allowed dispersion - as defined in RFC 5905 (16 seconds) */
+#define NTP_MAX_DISPERSION 16.0
+
+/* Maximum allowed time for server to process client packet */
+#define MAX_SERVER_INTERVAL 4.0
+
+/* Maximum acceptable delay in transmission for timestamp correction */
+#define MAX_TX_DELAY 1.0
+
+/* Maximum allowed values of maxdelay parameters */
+#define MAX_MAXDELAY 1.0e3
+#define MAX_MAXDELAYRATIO 1.0e6
+#define MAX_MAXDELAYDEVRATIO 1.0e6
+
+/* Parameters for the peer delay quantile */
+#define DELAY_QUANT_Q 100
+#define DELAY_QUANT_REPEAT 7
+
+/* Minimum and maximum allowed poll interval */
+#define MIN_POLL -7
+#define MAX_POLL 24
+
+/* Enable sub-second polling intervals only when the peer delay is not
+   longer than 10 milliseconds to restrict them to local networks */
+#define MIN_NONLAN_POLL 0
+#define MAX_LAN_PEER_DELAY 0.01
+
+/* Kiss-o'-Death codes */
+#define KOD_RATE 0x52415445UL /* RATE */
+
+/* Maximum poll interval set by KoD RATE */
+#define MAX_KOD_RATE_POLL SRC_DEFAULT_MAXPOLL
+
+/* Maximum number of missed responses to accept samples using old timestamps
+   in the interleaved client/server mode */
+#define MAX_CLIENT_INTERLEAVED_TX 4
+
+/* Maximum ratio of local intervals in the timestamp selection of the
+   interleaved mode to prefer a sample using previous timestamps */
+#define MAX_INTERLEAVED_L2L_RATIO 0.1
+
+/* Maximum acceptable change in server mono<->real offset */
+#define MAX_MONO_DOFFSET 16.0
+
+/* Invalid socket, different from the one in ntp_io.c */
+#define INVALID_SOCK_FD -2
+
+/* ================================================== */
+
+/* Server IPv4/IPv6 sockets */
+static int server_sock_fd4;
+static int server_sock_fd6;
+
+static ADF_AuthTable access_auth_table;
+
+/* Current offset between monotonic and cooked time, and its epoch ID
+   which is reset on clock steps */
+static double server_mono_offset;
+static uint32_t server_mono_epoch;
+
+/* Characters for printing synchronisation status and timestamping source */
+static const char leap_chars[4] = {'N', '+', '-', '?'};
+static const char tss_chars[3] = {'D', 'K', 'H'};
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void transmit_timeout(void *arg);
+static double get_transmit_delay(NCR_Instance inst, int on_tx);
+static double get_separation(int poll);
+static int parse_packet(NTP_Packet *packet, int length, NTP_PacketInfo *info);
+static void process_sample(NCR_Instance inst, NTP_Sample *sample);
+static int has_saved_response(NCR_Instance inst);
+static void process_saved_response(NCR_Instance inst);
+static int process_response(NCR_Instance inst, int saved, NTP_Local_Address *local_addr,
+                            NTP_Local_Timestamp *rx_ts, NTP_Packet *message,
+                            NTP_PacketInfo *info);
+static void set_connectivity(NCR_Instance inst, SRC_Connectivity connectivity);
+
+/* ================================================== */
+
+static void
+do_size_checks(void)
+{
+  /* Assertions to check the sizes of certain data types
+     and the positions of certain record fields */
+
+  /* Check that certain invariants are true */
+  assert(sizeof(NTP_int32) == 4);
+  assert(sizeof(NTP_int64) == 8);
+
+  /* Check offsets of all fields in the NTP packet format */
+  assert(offsetof(NTP_Packet, lvm)             ==  0);
+  assert(offsetof(NTP_Packet, stratum)         ==  1);
+  assert(offsetof(NTP_Packet, poll)            ==  2);
+  assert(offsetof(NTP_Packet, precision)       ==  3);
+  assert(offsetof(NTP_Packet, root_delay)      ==  4);
+  assert(offsetof(NTP_Packet, root_dispersion) ==  8);
+  assert(offsetof(NTP_Packet, reference_id)    == 12);
+  assert(offsetof(NTP_Packet, reference_ts)    == 16);
+  assert(offsetof(NTP_Packet, originate_ts)    == 24);
+  assert(offsetof(NTP_Packet, receive_ts)      == 32);
+  assert(offsetof(NTP_Packet, transmit_ts)     == 40);
+}
+
+/* ================================================== */
+
+static void
+do_time_checks(void)
+{
+  struct timespec now;
+  time_t warning_advance = 3600 * 24 * 365 * 10; /* 10 years */
+
+#ifdef HAVE_LONG_TIME_T
+  /* Check that time before NTP_ERA_SPLIT underflows correctly */
+
+  struct timespec ts1 = {NTP_ERA_SPLIT, 1}, ts2 = {NTP_ERA_SPLIT - 1, 1};
+  NTP_int64 nts1, nts2;
+  int r;
+
+  UTI_TimespecToNtp64(&ts1, &nts1, NULL);
+  UTI_TimespecToNtp64(&ts2, &nts2, NULL);
+  UTI_Ntp64ToTimespec(&nts1, &ts1);
+  UTI_Ntp64ToTimespec(&nts2, &ts2);
+
+  r = ts1.tv_sec == NTP_ERA_SPLIT &&
+      ts1.tv_sec + (1ULL << 32) - 1 == ts2.tv_sec;
+
+  assert(r);
+
+  LCL_ReadRawTime(&now);
+  if (ts2.tv_sec - now.tv_sec < warning_advance)
+    LOG(LOGS_WARN, "Assumed NTP time ends at %s!", UTI_TimeToLogForm(ts2.tv_sec));
+#else
+  LCL_ReadRawTime(&now);
+  if (now.tv_sec > 0x7fffffff - warning_advance)
+    LOG(LOGS_WARN, "System time ends at %s!", UTI_TimeToLogForm(0x7fffffff));
+#endif
+}
+
+/* ================================================== */
+
+static void
+zero_local_timestamp(NTP_Local_Timestamp *ts)
+{
+  UTI_ZeroTimespec(&ts->ts);
+  ts->err = 0.0;
+  ts->source = NTP_TS_DAEMON;
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type == LCL_ChangeAdjust) {
+    server_mono_offset += doffset;
+  } else {
+    UTI_GetRandomBytes(&server_mono_epoch, sizeof (server_mono_epoch));
+    server_mono_offset = 0.0;
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_Initialise(void)
+{
+  do_size_checks();
+  do_time_checks();
+
+  logfileid = CNF_GetLogMeasurements(&log_raw_measurements) ? LOG_FileOpen("measurements",
+      "   Date (UTC) Time     IP Address   L St 123 567 ABCD  LP RP Score    Offset  Peer del. Peer disp.  Root del. Root disp. Refid     MTxRx")
+    : -1;
+
+  access_auth_table = ADF_CreateTable();
+  broadcasts = ARR_CreateInstance(sizeof (BroadcastDestination));
+
+  /* Server socket will be opened when access is allowed */
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+  handle_slew(NULL, NULL, 0.0, 0.0, LCL_ChangeUnknownStep, NULL);
+}
+
+/* ================================================== */
+
+void
+NCR_Finalise(void)
+{
+  unsigned int i;
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  if (server_sock_fd4 != INVALID_SOCK_FD)
+    NIO_CloseServerSocket(server_sock_fd4);
+  if (server_sock_fd6 != INVALID_SOCK_FD)
+    NIO_CloseServerSocket(server_sock_fd6);
+
+  for (i = 0; i < ARR_GetSize(broadcasts); i++) {
+    NIO_CloseServerSocket(((BroadcastDestination *)ARR_GetElement(broadcasts, i))->local_addr.sock_fd);
+    NAU_DestroyInstance(((BroadcastDestination *)ARR_GetElement(broadcasts, i))->auth);
+  }
+
+  ARR_DestroyInstance(broadcasts);
+  ADF_DestroyTable(access_auth_table);
+}
+
+/* ================================================== */
+
+static void
+restart_timeout(NCR_Instance inst, double delay)
+{
+  /* Check if we can transmit */
+  if (inst->tx_suspended) {
+    assert(!inst->tx_timeout_id);
+    return;
+  }
+
+  /* Stop both rx and tx timers if running */
+  SCH_RemoveTimeout(inst->rx_timeout_id);
+  inst->rx_timeout_id = 0;
+  SCH_RemoveTimeout(inst->tx_timeout_id);
+
+  /* Start new timer for transmission */
+  inst->tx_timeout_id = SCH_AddTimeoutInClass(delay, get_separation(inst->local_poll),
+                                              SAMPLING_RANDOMNESS,
+                                              inst->mode == MODE_CLIENT ?
+                                                SCH_NtpClientClass : SCH_NtpPeerClass,
+                                              transmit_timeout, (void *)inst);
+}
+
+/* ================================================== */
+
+static void
+start_initial_timeout(NCR_Instance inst)
+{
+  double delay;
+
+  if (!inst->tx_timeout_id) {
+    /* This will be the first transmission after mode change */
+
+    /* Mark source active */
+    SRC_SetActive(inst->source);
+  }
+
+  /* In case the offline period was too short, adjust the delay to keep
+     the interval between packets at least as long as the current polling
+     interval */
+  if (!UTI_IsZeroTimespec(&inst->local_tx.ts)) {
+    delay = get_transmit_delay(inst, 0);
+  } else {
+    delay = 0.0;
+  }
+
+  if (delay < INITIAL_DELAY)
+    delay = INITIAL_DELAY;
+
+  restart_timeout(inst, delay);
+}
+
+/* ================================================== */
+
+static void
+close_client_socket(NCR_Instance inst)
+{
+  if (inst->mode == MODE_CLIENT && inst->local_addr.sock_fd != INVALID_SOCK_FD) {
+    NIO_CloseClientSocket(inst->local_addr.sock_fd);
+    inst->local_addr.sock_fd = INVALID_SOCK_FD;
+  }
+
+  SCH_RemoveTimeout(inst->rx_timeout_id);
+  inst->rx_timeout_id = 0;
+
+  if (has_saved_response(inst)) {
+    SCH_RemoveTimeout(inst->saved_response->timeout_id);
+    inst->saved_response->timeout_id = 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+take_offline(NCR_Instance inst)
+{
+  inst->opmode = MD_OFFLINE;
+
+  SCH_RemoveTimeout(inst->tx_timeout_id);
+  inst->tx_timeout_id = 0;
+
+  /* Mark source unreachable */
+  SRC_ResetReachability(inst->source);
+
+  /* And inactive */
+  SRC_UnsetActive(inst->source);
+
+  close_client_socket(inst);
+
+  NCR_ResetInstance(inst);
+}
+
+/* ================================================== */
+
+static void
+reset_report(NCR_Instance inst)
+{
+  memset(&inst->report, 0, sizeof (inst->report));
+  inst->report.remote_addr = inst->remote_addr.ip_addr;
+  inst->report.remote_port = inst->remote_addr.port;
+}
+
+/* ================================================== */
+
+NCR_Instance
+NCR_CreateInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                   SourceParameters *params, const char *name)
+{
+  NCR_Instance result;
+
+  result = MallocNew(struct NCR_Instance_Record);
+
+  result->remote_addr = *remote_addr;
+  result->local_addr.ip_addr.family = IPADDR_UNSPEC;
+  result->local_addr.if_index = INVALID_IF_INDEX;
+
+  switch (type) {
+    case NTP_SERVER:
+      /* Client socket will be obtained when sending request */
+      result->local_addr.sock_fd = INVALID_SOCK_FD;
+      result->mode = MODE_CLIENT;
+      break;
+    case NTP_PEER:
+      result->local_addr.sock_fd = NIO_OpenServerSocket(remote_addr);
+      result->mode = MODE_ACTIVE;
+      break;
+    default:
+      assert(0);
+  }
+
+  result->interleaved = params->interleaved;
+
+  result->minpoll = params->minpoll;
+  if (result->minpoll < MIN_POLL)
+    result->minpoll = SRC_DEFAULT_MINPOLL;
+  else if (result->minpoll > MAX_POLL)
+    result->minpoll = MAX_POLL;
+
+  result->maxpoll = params->maxpoll;
+  if (result->maxpoll < MIN_POLL)
+    result->maxpoll = SRC_DEFAULT_MAXPOLL;
+  else if (result->maxpoll > MAX_POLL)
+    result->maxpoll = MAX_POLL;
+  if (result->maxpoll < result->minpoll)
+    result->maxpoll = result->minpoll;
+
+  result->min_stratum = params->min_stratum;
+  if (result->min_stratum >= NTP_MAX_STRATUM)
+    result->min_stratum = NTP_MAX_STRATUM - 1;
+
+  /* Presend doesn't work in symmetric mode */
+  result->presend_minpoll = params->presend_minpoll;
+  if (result->presend_minpoll <= MAX_POLL && result->mode != MODE_CLIENT)
+    result->presend_minpoll = MAX_POLL + 1;
+
+  result->max_delay = CLAMP(0.0, params->max_delay, MAX_MAXDELAY);
+  result->max_delay_ratio = CLAMP(0.0, params->max_delay_ratio, MAX_MAXDELAYRATIO);
+  result->max_delay_dev_ratio = CLAMP(0.0, params->max_delay_dev_ratio, MAX_MAXDELAYDEVRATIO);
+  result->offset_correction = params->offset;
+  result->auto_iburst = params->iburst;
+  result->auto_burst = params->burst;
+  result->auto_offline = params->auto_offline;
+  result->copy = params->copy && result->mode == MODE_CLIENT;
+  result->poll_target = MAX(1, params->poll_target);
+  result->ext_field_flags = params->ext_fields;
+
+  if (params->nts) {
+    IPSockAddr nts_address;
+
+    if (result->mode == MODE_ACTIVE)
+      LOG(LOGS_WARN, "NTS not supported with peers");
+
+    nts_address.ip_addr = remote_addr->ip_addr;
+    nts_address.port = params->nts_port;
+
+    result->auth = NAU_CreateNtsInstance(&nts_address, name, params->cert_set,
+                                         result->remote_addr.port);
+  } else if (params->authkey != INACTIVE_AUTHKEY) {
+    result->auth = NAU_CreateSymmetricInstance(params->authkey);
+  } else {
+    result->auth = NAU_CreateNoneInstance();
+  }
+
+  if (result->ext_field_flags || result->interleaved)
+    result->version = NTP_VERSION;
+  else
+    result->version = NAU_GetSuggestedNtpVersion(result->auth);
+
+  if (params->version)
+    result->version = CLAMP(NTP_MIN_COMPAT_VERSION, params->version, NTP_VERSION);
+
+  /* Create a source instance for this NTP source */
+  result->source = SRC_CreateNewInstance(UTI_IPToRefid(&remote_addr->ip_addr),
+                                         SRC_NTP, NAU_IsAuthEnabled(result->auth),
+                                         params->sel_options, &result->remote_addr.ip_addr,
+                                         params->min_samples, params->max_samples,
+                                         params->min_delay, params->asymmetry);
+
+  if (params->max_delay_quant > 0.0) {
+    int k = round(CLAMP(0.05, params->max_delay_quant, 0.95) * DELAY_QUANT_Q);
+    result->delay_quant = QNT_CreateInstance(k, k, DELAY_QUANT_Q, DELAY_QUANT_REPEAT,
+                                             LCL_GetSysPrecisionAsQuantum() / 2.0);
+  } else {
+    result->delay_quant = NULL;
+  }
+
+  if (params->filter_length >= 1)
+    result->filter = SPF_CreateInstance(1, params->filter_length, NTP_MAX_DISPERSION, 0.0);
+  else
+    result->filter = NULL;
+
+  result->saved_response = NULL;
+
+  result->rx_timeout_id = 0;
+  result->tx_timeout_id = 0;
+  result->tx_suspended = 1;
+  result->opmode = MD_OFFLINE;
+  result->local_poll = MAX(result->minpoll, MIN_NONLAN_POLL);
+  result->poll_score = 0.0;
+  zero_local_timestamp(&result->local_tx);
+  result->burst_good_samples_to_go = 0;
+  result->burst_total_samples_to_go = 0;
+  
+  NCR_ResetInstance(result);
+
+  set_connectivity(result, params->connectivity);
+
+  reset_report(result);
+
+  return result;
+}
+
+/* ================================================== */
+
+/* Destroy an instance */
+void
+NCR_DestroyInstance(NCR_Instance instance)
+{
+  if (instance->opmode != MD_OFFLINE)
+    take_offline(instance);
+
+  if (instance->mode == MODE_ACTIVE)
+    NIO_CloseServerSocket(instance->local_addr.sock_fd);
+
+  if (instance->delay_quant)
+    QNT_DestroyInstance(instance->delay_quant);
+  if (instance->filter)
+    SPF_DestroyInstance(instance->filter);
+
+  if (instance->saved_response)
+    Free(instance->saved_response);
+
+  NAU_DestroyInstance(instance->auth);
+
+  /* This will destroy the source instance inside the
+     structure, which will cause reselection if this was the
+     synchronising source etc. */
+  SRC_DestroyInstance(instance->source);
+
+  /* Free the data structure */
+  Free(instance);
+}
+
+/* ================================================== */
+
+void
+NCR_StartInstance(NCR_Instance instance)
+{
+  instance->tx_suspended = 0;
+  if (instance->opmode != MD_OFFLINE)
+    start_initial_timeout(instance);
+}
+
+/* ================================================== */
+
+void
+NCR_ResetInstance(NCR_Instance instance)
+{
+  instance->tx_count = 0;
+  instance->presend_done = 0;
+
+  instance->remote_poll = 0;
+  instance->remote_stratum = 0;
+  instance->remote_root_delay = 0.0;
+  instance->remote_root_dispersion = 0.0;
+  instance->remote_mono_epoch = 0;
+  instance->mono_doffset = 0.0;
+
+  instance->valid_rx = 0;
+  instance->valid_timestamps = 0;
+  UTI_ZeroNtp64(&instance->remote_ntp_monorx);
+  UTI_ZeroNtp64(&instance->remote_ntp_rx);
+  UTI_ZeroNtp64(&instance->remote_ntp_tx);
+  UTI_ZeroNtp64(&instance->local_ntp_rx);
+  UTI_ZeroNtp64(&instance->local_ntp_tx);
+  zero_local_timestamp(&instance->local_rx);
+
+  zero_local_timestamp(&instance->prev_local_tx);
+  instance->prev_local_poll = 0;
+  instance->prev_tx_count = 0;
+
+  instance->updated_init_timestamps = 0;
+  UTI_ZeroNtp64(&instance->init_remote_ntp_tx);
+  zero_local_timestamp(&instance->init_local_rx);
+
+  if (instance->delay_quant)
+    QNT_Reset(instance->delay_quant);
+  if (instance->filter)
+    SPF_DropSamples(instance->filter);
+  instance->filter_count = 0;
+}
+
+/* ================================================== */
+
+void
+NCR_ResetPoll(NCR_Instance instance)
+{
+  instance->poll_score = 0.0;
+
+  if (instance->local_poll != instance->minpoll) {
+    instance->local_poll = instance->minpoll;
+
+    /* The timer was set with a longer poll interval, restart it */
+    if (instance->tx_timeout_id)
+      restart_timeout(instance, get_transmit_delay(instance, 0));
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_ChangeRemoteAddress(NCR_Instance inst, NTP_Remote_Address *remote_addr, int ntp_only)
+{
+  NCR_ResetInstance(inst);
+
+  if (!ntp_only)
+    NAU_ChangeAddress(inst->auth, &remote_addr->ip_addr);
+
+  inst->remote_addr = *remote_addr;
+
+  if (inst->mode == MODE_CLIENT)
+    close_client_socket(inst);
+  else {
+    NIO_CloseServerSocket(inst->local_addr.sock_fd);
+    inst->local_addr.ip_addr.family = IPADDR_UNSPEC;
+    inst->local_addr.if_index = INVALID_IF_INDEX;
+    inst->local_addr.sock_fd = NIO_OpenServerSocket(remote_addr);
+  }
+
+  /* Reset the polling interval only if the source wasn't unreachable to
+     avoid increasing server/network load in case that is what caused
+     the source to be unreachable */
+  if (SRC_IsReachable(inst->source))
+    NCR_ResetPoll(inst);
+
+  /* Update the reference ID and reset the source/sourcestats instances */
+  SRC_SetRefid(inst->source, UTI_IPToRefid(&remote_addr->ip_addr),
+               &inst->remote_addr.ip_addr);
+  SRC_ResetInstance(inst->source);
+
+  reset_report(inst);
+}
+
+/* ================================================== */
+
+static void
+adjust_poll(NCR_Instance inst, double adj)
+{
+  NTP_Sample last_sample;
+
+  inst->poll_score += adj;
+
+  if (inst->poll_score >= 1.0) {
+    inst->local_poll += (int)inst->poll_score;
+    inst->poll_score -= (int)inst->poll_score;
+  }
+
+  if (inst->poll_score < 0.0) {
+    inst->local_poll += (int)(inst->poll_score - 1.0);
+    inst->poll_score -= (int)(inst->poll_score - 1.0);
+  }
+  
+  /* Clamp polling interval to defined range */
+  if (inst->local_poll < inst->minpoll) {
+    inst->local_poll = inst->minpoll;
+    inst->poll_score = 0;
+  } else if (inst->local_poll > inst->maxpoll) {
+    inst->local_poll = inst->maxpoll;
+    inst->poll_score = 1.0;
+  }
+
+  /* Don't allow a sub-second polling interval if the source is not reachable
+     or it is not in a local network according to the measured delay */
+  if (inst->local_poll < MIN_NONLAN_POLL &&
+      (!SRC_IsReachable(inst->source) ||
+       (SST_MinRoundTripDelay(SRC_GetSourcestats(inst->source)) > MAX_LAN_PEER_DELAY &&
+        (!inst->filter || !SPF_GetLastSample(inst->filter, &last_sample) ||
+         last_sample.peer_delay > MAX_LAN_PEER_DELAY))))
+    inst->local_poll = MIN_NONLAN_POLL;
+}
+
+/* ================================================== */
+
+static double
+get_poll_adj(NCR_Instance inst, double error_in_estimate, double peer_distance)
+{
+  double poll_adj;
+  int samples;
+
+  if (error_in_estimate > peer_distance) {
+    /* If the prediction is not even within +/- the peer distance of the peer,
+       we are clearly not tracking the peer at all well, so we back off the
+       sampling rate depending on just how bad the situation is */
+    poll_adj = -log(error_in_estimate / peer_distance) / log(2.0);
+  } else {
+    samples = SST_Samples(SRC_GetSourcestats(inst->source));
+
+    /* Adjust polling interval so that the number of sourcestats samples
+       remains close to the target value */
+    poll_adj = ((double)samples / inst->poll_target - 1.0) / inst->poll_target;
+
+    /* Make interval shortening quicker */
+    if (samples < inst->poll_target) {
+      poll_adj *= 2.0;
+    }
+  }
+
+  return poll_adj;
+}
+
+/* ================================================== */
+
+static int
+get_transmit_poll(NCR_Instance inst)
+{
+  int poll;
+
+  poll = inst->local_poll;
+
+  /* In symmetric mode, if the peer is responding, use shorter of the local
+     and remote poll interval, but not shorter than the minimum */
+  if (inst->mode == MODE_ACTIVE && poll > inst->remote_poll &&
+      SRC_IsReachable(inst->source))
+    poll = MAX(inst->remote_poll, inst->minpoll);
+
+  return poll;
+}
+
+/* ================================================== */
+
+static double
+get_transmit_delay(NCR_Instance inst, int on_tx)
+{
+  int poll_to_use, stratum_diff;
+  double delay_time, last_tx;
+  struct timespec now;
+
+  /* Calculate the interval since last transmission if known */
+  if (!on_tx && !UTI_IsZeroTimespec(&inst->local_tx.ts)) {
+    SCH_GetLastEventTime(&now, NULL, NULL);
+    last_tx = UTI_DiffTimespecsToDouble(&now, &inst->local_tx.ts);
+  } else {
+    last_tx = 0;
+  }
+
+  /* If we're in burst mode, queue for immediate dispatch.
+
+     If we're operating in client/server mode, queue the timeout for
+     the poll interval hence.  The fact that a timeout has been queued
+     in the transmit handler is immaterial - that is only done so that
+     we at least send something, if no reply is heard.
+
+     If we're in symmetric mode, we have to take account of the peer's
+     wishes, otherwise his sampling regime will fall to pieces.  If
+     we're in client/server mode, we don't care what poll interval the
+     server responded with last time. */
+
+  poll_to_use = get_transmit_poll(inst);
+  delay_time = UTI_Log2ToDouble(poll_to_use);
+
+  switch (inst->opmode) {
+    case MD_OFFLINE:
+      assert(0);
+      break;
+    case MD_ONLINE:
+      switch(inst->mode) {
+        case MODE_CLIENT:
+          if (inst->presend_done)
+            delay_time = WARM_UP_DELAY;
+          break;
+
+        case MODE_ACTIVE:
+          /* If the remote stratum is higher than ours, wait a bit for the next
+             packet before responding in order to minimize the delay of the
+             measurement and its error for the peer which has higher stratum.
+             If the remote stratum is equal to ours, try to interleave packets
+             evenly with the peer. */
+          stratum_diff = inst->remote_stratum - REF_GetOurStratum();
+          if ((stratum_diff > 0 && last_tx * PEER_SAMPLING_ADJ < delay_time) ||
+              (!on_tx && !stratum_diff &&
+               last_tx / delay_time > PEER_SAMPLING_ADJ - 0.5))
+            delay_time *= PEER_SAMPLING_ADJ;
+
+          break;
+        default:
+          assert(0);
+          break;
+      }
+      break;
+
+    case MD_BURST_WAS_ONLINE:
+    case MD_BURST_WAS_OFFLINE:
+      /* Burst modes */
+      delay_time = MIN(MAX_BURST_INTERVAL, MAX_BURST_POLL_RATIO * delay_time);
+      break;
+    default:
+      assert(0);
+      break;
+  }
+
+  /* Subtract elapsed time */
+  if (last_tx > 0.0)
+    delay_time -= last_tx;
+  if (delay_time < 0.0)
+    delay_time = 0.0;
+
+  return delay_time;
+}
+
+/* ================================================== */
+/* Calculate sampling separation for given polling interval */
+
+static double
+get_separation(int poll)
+{
+  double separation;
+
+  assert(poll >= MIN_POLL && poll <= MAX_POLL);
+
+  /* Allow up to 8 sources using the same short interval to not be limited
+     by the separation */
+  separation = UTI_Log2ToDouble(poll - 3);
+
+  return CLAMP(MIN_SAMPLING_SEPARATION, separation, MAX_SAMPLING_SEPARATION);
+}
+
+/* ================================================== */
+/* Timeout handler for closing the client socket when no acceptable
+   reply can be received from the server */
+
+static void
+receive_timeout(void *arg)
+{
+  NCR_Instance inst = (NCR_Instance)arg;
+
+  DEBUG_LOG("Receive timeout for %s", UTI_IPSockAddrToString(&inst->remote_addr));
+
+  inst->rx_timeout_id = 0;
+  close_client_socket(inst);
+}
+
+/* ================================================== */
+
+static int
+add_ext_exp1(NTP_Packet *message, NTP_PacketInfo *info, struct timespec *rx,
+             double root_delay, double root_dispersion)
+{
+  struct timespec mono_rx;
+  NTP_ExtFieldExp1 exp1;
+  NTP_int64 ts_fuzz;
+
+  memset(&exp1, 0, sizeof (exp1));
+  exp1.magic = htonl(NTP_EF_EXP1_MAGIC);
+
+  if (info->mode != MODE_CLIENT) {
+    exp1.root_delay = UTI_DoubleToNtp32f28(root_delay);
+    exp1.root_dispersion = UTI_DoubleToNtp32f28(root_dispersion);
+    if (rx)
+      UTI_AddDoubleToTimespec(rx, server_mono_offset, &mono_rx);
+    else
+      UTI_ZeroTimespec(&mono_rx);
+    UTI_GetNtp64Fuzz(&ts_fuzz, message->precision);
+    UTI_TimespecToNtp64(&mono_rx, &exp1.mono_receive_ts, &ts_fuzz);
+    exp1.mono_epoch = htonl(server_mono_epoch);
+  }
+
+  if (!NEF_AddField(message, info, NTP_EF_EXP1, &exp1, sizeof (exp1))) {
+    DEBUG_LOG("Could not add EF");
+    return 0;
+  }
+
+  info->ext_field_flags |= NTP_EF_FLAG_EXP1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+transmit_packet(NTP_Mode my_mode, /* The mode this machine wants to be */
+                int interleaved, /* Flag enabling interleaved mode */
+                int my_poll, /* The log2 of the local poll interval */
+                int version, /* The NTP version to be set in the packet */
+                uint32_t kod, /* KoD code - 0 disabled */
+                int ext_field_flags, /* Extension fields to be included in the packet */
+                NAU_Instance auth, /* The authentication to be used for the packet */
+                NTP_int64 *remote_ntp_rx, /* The receive timestamp from received packet */
+                NTP_int64 *remote_ntp_tx, /* The transmit timestamp from received packet */
+                NTP_Local_Timestamp *local_rx, /* The RX time of the received packet */
+                NTP_Local_Timestamp *local_tx, /* The TX time of the previous packet
+                                                  RESULT : TX time of this packet */
+                NTP_int64 *local_ntp_rx, /* The receive timestamp from the previous packet
+                                            RESULT : receive timestamp from this packet */
+                NTP_int64 *local_ntp_tx, /* The transmit timestamp from the previous packet
+                                            RESULT : transmit timestamp from this packet */
+                NTP_Remote_Address *where_to, /* Where to address the reponse to */
+                NTP_Local_Address *from,      /* From what address to send it */
+                NTP_Packet *request,          /* The received packet if responding */
+                NTP_PacketInfo *request_info  /* and its info */
+                )
+{
+  NTP_PacketInfo info;
+  NTP_Packet message;
+  struct timespec local_receive, local_transmit;
+  double smooth_offset, local_transmit_err;
+  int ret, precision;
+  NTP_int64 ts_fuzz;
+
+  /* Parameters read from reference module */
+  int are_we_synchronised, our_stratum, smooth_time;
+  NTP_Leap leap_status;
+  uint32_t our_ref_id;
+  struct timespec our_ref_time;
+  double our_root_delay, our_root_dispersion;
+
+  assert(auth || (request && request_info));
+
+  /* Don't reply with version higher than ours */
+  if (version > NTP_VERSION) {
+    version = NTP_VERSION;
+  }
+
+  /* Check if the packet can be formed in the interleaved mode */
+  if (interleaved && (!remote_ntp_rx || !local_tx || UTI_IsZeroTimespec(&local_tx->ts)))
+    interleaved = 0;
+
+  smooth_time = 0;
+  smooth_offset = 0.0;
+
+  /* Get an initial transmit timestamp.  A more accurate timestamp will be
+     taken later in this function. */
+  SCH_GetLastEventTime(&local_transmit, NULL, NULL);
+
+  if (my_mode == MODE_CLIENT) {
+    /* Don't reveal local time or state of the clock in client packets */
+    precision = 32;
+    leap_status = our_stratum = our_ref_id = 0;
+    our_root_delay = our_root_dispersion = 0.0;
+    UTI_ZeroTimespec(&our_ref_time);
+  } else {
+    REF_GetReferenceParams(&local_transmit,
+                           &are_we_synchronised, &leap_status,
+                           &our_stratum,
+                           &our_ref_id, &our_ref_time,
+                           &our_root_delay, &our_root_dispersion);
+
+    /* Get current smoothing offset when sending packet to a client */
+    if (SMT_IsEnabled() && (my_mode == MODE_SERVER || my_mode == MODE_BROADCAST)) {
+      smooth_offset = SMT_GetOffset(&local_transmit);
+      smooth_time = fabs(smooth_offset) > LCL_GetSysPrecisionAsQuantum();
+
+      /* Suppress leap second when smoothing and slew mode are enabled */
+      if (REF_GetLeapMode() == REF_LeapModeSlew &&
+          (leap_status == LEAP_InsertSecond || leap_status == LEAP_DeleteSecond))
+        leap_status = LEAP_Normal;
+    }
+
+    precision = LCL_GetSysPrecisionAsLog();
+  }
+
+  if (smooth_time && !UTI_IsZeroTimespec(&local_rx->ts)) {
+    our_ref_id = NTP_REFID_SMOOTH;
+    UTI_AddDoubleToTimespec(&our_ref_time, smooth_offset, &our_ref_time);
+    UTI_AddDoubleToTimespec(&local_rx->ts, smooth_offset, &local_receive);
+  } else {
+    local_receive = local_rx->ts;
+  }
+
+  if (kod != 0) {
+    leap_status = LEAP_Unsynchronised;
+    our_stratum = NTP_INVALID_STRATUM;
+    our_ref_id = kod;
+  }
+
+  /* Generate transmit packet */
+  message.lvm = NTP_LVM(leap_status, version, my_mode);
+  /* Stratum 16 and larger are invalid */
+  if (our_stratum < NTP_MAX_STRATUM) {
+    message.stratum = our_stratum;
+  } else {
+    message.stratum = NTP_INVALID_STRATUM;
+  }
+ 
+  message.poll = my_poll;
+  message.precision = precision;
+  message.root_delay = UTI_DoubleToNtp32(our_root_delay);
+  message.root_dispersion = UTI_DoubleToNtp32(our_root_dispersion);
+  message.reference_id = htonl(our_ref_id);
+
+  /* Now fill in timestamps */
+
+  UTI_TimespecToNtp64(&our_ref_time, &message.reference_ts, NULL);
+
+  /* Don't reveal timestamps which are not necessary for the protocol */
+
+  if (my_mode != MODE_CLIENT || interleaved) {
+    /* Originate - this comes from the last packet the source sent us */
+    message.originate_ts = interleaved ? *remote_ntp_rx : *remote_ntp_tx;
+
+    do {
+      /* Prepare random bits which will be added to the receive timestamp */
+      UTI_GetNtp64Fuzz(&ts_fuzz, precision);
+
+      /* Receive - this is when we received the last packet from the source.
+         This timestamp will have been adjusted so that it will now look to
+         the source like we have been running on our latest estimate of
+         frequency all along */
+      UTI_TimespecToNtp64(&local_receive, &message.receive_ts, &ts_fuzz);
+
+      /* Do not send a packet with a non-zero receive timestamp equal to the
+         originate timestamp or previous receive timestamp */
+    } while (!UTI_IsZeroNtp64(&message.receive_ts) &&
+             UTI_IsEqualAnyNtp64(&message.receive_ts, &message.originate_ts,
+                                 local_ntp_rx, NULL));
+  } else {
+    UTI_ZeroNtp64(&message.originate_ts);
+    UTI_ZeroNtp64(&message.receive_ts);
+  }
+
+  if (!parse_packet(&message, NTP_HEADER_LENGTH, &info))
+    return 0;
+
+  if (ext_field_flags) {
+    if (ext_field_flags & NTP_EF_FLAG_EXP1) {
+      if (!add_ext_exp1(&message, &info, smooth_time ? NULL : &local_receive,
+                        our_root_delay, our_root_dispersion))
+        return 0;
+    }
+  }
+
+  do {
+    /* Prepare random bits which will be added to the transmit timestamp */
+    UTI_GetNtp64Fuzz(&ts_fuzz, precision);
+
+    /* Get a more accurate transmit timestamp if it needs to be saved in the
+       packet (i.e. in the server, symmetric, and broadcast basic modes) */
+    if (!interleaved && precision < 32) {
+      LCL_ReadCookedTime(&local_transmit, &local_transmit_err);
+      if (smooth_time)
+        UTI_AddDoubleToTimespec(&local_transmit, smooth_offset, &local_transmit);
+    }
+
+    UTI_TimespecToNtp64(interleaved ? &local_tx->ts : &local_transmit,
+                        &message.transmit_ts, &ts_fuzz);
+
+    /* Do not send a packet with a non-zero transmit timestamp which is
+       equal to any of the following timestamps:
+       - receive (to allow reliable detection of the interleaved mode)
+       - originate (to prevent the packet from being its own valid response
+                    in the symmetric mode)
+       - previous transmit (to invalidate responses to the previous packet)
+       (the precision must be at least -30 to prevent an infinite loop!) */
+  } while (!UTI_IsZeroNtp64(&message.transmit_ts) &&
+           UTI_IsEqualAnyNtp64(&message.transmit_ts, &message.receive_ts,
+                               &message.originate_ts, local_ntp_tx));
+
+  /* Encode in server timestamps a flag indicating RX timestamp to avoid
+     saving all RX timestamps for detection of interleaved requests */
+  if (my_mode == MODE_SERVER || my_mode == MODE_PASSIVE) {
+    message.receive_ts.lo |= htonl(1);
+    message.transmit_ts.lo &= ~htonl(1);
+  }
+
+  /* Generate the authentication data */
+  if (auth) {
+    if (!NAU_GenerateRequestAuth(auth, &message, &info)) {
+      DEBUG_LOG("Could not generate request auth");
+      return 0;
+    }
+  } else {
+    if (!NAU_GenerateResponseAuth(request, request_info, &message, &info,
+                                  where_to, from, kod)) {
+      DEBUG_LOG("Could not generate response auth");
+      return 0;
+    }
+  }
+
+  if (request_info && request_info->length < info.length) {
+    DEBUG_LOG("Response longer than request req_len=%d res_len=%d",
+              request_info->length, info.length);
+    return 0;
+  }
+
+  /* If the transmit timestamp will be saved, get an even more
+     accurate daemon timestamp closer to the transmission */
+  if (local_tx)
+    LCL_ReadCookedTime(&local_transmit, &local_transmit_err);
+
+  ret = NIO_SendPacket(&message, where_to, from, info.length, local_tx != NULL);
+
+  if (local_tx) {
+    if (smooth_time)
+      UTI_AddDoubleToTimespec(&local_transmit, smooth_offset, &local_transmit);
+    local_tx->ts = local_transmit;
+    local_tx->err = local_transmit_err;
+    local_tx->source = NTP_TS_DAEMON;
+  }
+
+  if (local_ntp_rx)
+    *local_ntp_rx = message.receive_ts;
+  if (local_ntp_tx)
+    *local_ntp_tx = message.transmit_ts;
+
+  return ret;
+}
+
+/* ================================================== */
+/* Timeout handler for transmitting to a source. */
+
+static void
+transmit_timeout(void *arg)
+{
+  NCR_Instance inst = (NCR_Instance) arg;
+  NTP_Local_Address local_addr;
+  int interleaved, initial, sent;
+
+  inst->tx_timeout_id = 0;
+
+  if (has_saved_response(inst)) {
+    process_saved_response(inst);
+
+    /* Wait for the new transmission timeout (if the response was still
+       valid and it did not cause switch to offline) */
+    if (inst->tx_timeout_id != 0)
+      return;
+  }
+
+  switch (inst->opmode) {
+    case MD_BURST_WAS_ONLINE:
+      /* With online burst switch to online before last packet */
+      if (inst->burst_total_samples_to_go <= 1)
+        inst->opmode = MD_ONLINE;
+      break;
+    case MD_BURST_WAS_OFFLINE:
+      if (inst->burst_total_samples_to_go <= 0)
+        take_offline(inst);
+      break;
+    case MD_ONLINE:
+      /* Start a new burst if the burst option is enabled and the average
+         polling interval including the burst will not fall below the
+         minimum polling interval */
+      if (inst->auto_burst && inst->local_poll > inst->minpoll)
+        NCR_InitiateSampleBurst(inst, BURST_GOOD_SAMPLES,
+                                MIN(1 << (inst->local_poll - inst->minpoll),
+                                    MAX_BURST_TOTAL_SAMPLES));
+      break;
+    default:
+      break;
+  }
+
+  if (inst->opmode == MD_OFFLINE) {
+    return;
+  }
+
+  DEBUG_LOG("Transmit timeout for %s", UTI_IPSockAddrToString(&inst->remote_addr));
+
+  /* Prepare authentication */
+  if (!NAU_PrepareRequestAuth(inst->auth)) {
+    SRC_UpdateReachability(inst->source, 0);
+    restart_timeout(inst, get_transmit_delay(inst, 1));
+    /* Count missing samples for the sample filter */
+    process_sample(inst, NULL);
+    return;
+  }
+
+  /* Open new client socket */
+  if (inst->mode == MODE_CLIENT) {
+    close_client_socket(inst);
+    assert(inst->local_addr.sock_fd == INVALID_SOCK_FD);
+    inst->local_addr.sock_fd = NIO_OpenClientSocket(&inst->remote_addr);
+  }
+
+  /* Don't require the packet to be sent from the same address as before */
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = inst->local_addr.sock_fd;
+
+  /* In symmetric mode, don't send a packet in interleaved mode unless it
+     is the first response to the last valid request received from the peer
+     and there was just one response to the previous valid request.  This
+     prevents the peer from matching the transmit timestamp with an older
+     response if it can't detect missed responses.  In client mode, which has
+     at most one response per request, check how many responses are missing to
+     prevent the server from responding with a very old transmit timestamp. */
+  interleaved = inst->interleaved &&
+                ((inst->mode == MODE_CLIENT &&
+                  inst->tx_count < MAX_CLIENT_INTERLEAVED_TX) ||
+                 (inst->mode == MODE_ACTIVE &&
+                  inst->prev_tx_count == 1 && inst->tx_count == 0));
+
+  /* In symmetric mode, if no valid response was received since the previous
+     transmission, respond to the last received packet even if it failed some
+     specific NTP tests.  This is necessary for starting and restarting the
+     protocol, e.g. when a packet was lost. */
+  initial = inst->mode == MODE_ACTIVE && !inst->valid_rx &&
+            !UTI_IsZeroNtp64(&inst->init_remote_ntp_tx);
+
+  /* Prepare for the response */
+  inst->valid_rx = 0;
+  inst->updated_init_timestamps = 0;
+  if (initial)
+    inst->valid_timestamps = 0;
+
+  /* Check whether we need to 'warm up' the link to the other end by
+     sending an NTP exchange to ensure both ends' ARP caches are
+     primed or whether we need to send two packets first to ensure a
+     server in the interleaved mode has a fresh timestamp for us. */
+  if (inst->presend_minpoll <= inst->local_poll && !inst->presend_done &&
+      !inst->burst_total_samples_to_go) {
+    inst->presend_done = interleaved ? 2 : 1;
+  } else if (inst->presend_done > 0) {
+    inst->presend_done--;
+  }
+
+  /* Send the request (which may also be a response in the symmetric mode) */
+  sent = transmit_packet(inst->mode, interleaved, inst->local_poll, inst->version, 0,
+                         inst->ext_field_flags, inst->auth,
+                         initial ? NULL : &inst->remote_ntp_rx,
+                         initial ? &inst->init_remote_ntp_tx : &inst->remote_ntp_tx,
+                         initial ? &inst->init_local_rx : &inst->local_rx,
+                         &inst->local_tx, &inst->local_ntp_rx, &inst->local_ntp_tx,
+                         &inst->remote_addr, &local_addr, NULL, NULL);
+
+  ++inst->tx_count;
+  if (sent)
+    inst->report.total_tx_count++;
+
+  /* If the source loses connectivity and our packets are still being sent,
+     back off the sampling rate to reduce the network traffic.  If it's the
+     source to which we are currently locked, back off slowly. */
+
+  if (inst->tx_count >= 2) {
+    /* Implies we have missed at least one transmission */
+
+    if (sent) {
+      adjust_poll(inst, SRC_IsSyncPeer(inst->source) ? 0.1 : 0.25);
+    }
+
+    SRC_UpdateReachability(inst->source, 0);
+
+    /* Count missing samples for the sample filter */
+    process_sample(inst, NULL);
+  }
+
+  /* With auto_offline take the source offline if sending failed */
+  if (!sent && inst->auto_offline)
+    NCR_SetConnectivity(inst, SRC_OFFLINE);
+
+  switch (inst->opmode) {
+    case MD_BURST_WAS_ONLINE:
+      /* When not reachable, don't stop online burst until sending succeeds */
+      if (!sent && !SRC_IsReachable(inst->source))
+        break;
+      /* Fall through */
+    case MD_BURST_WAS_OFFLINE:
+      --inst->burst_total_samples_to_go;
+      break;
+    case MD_OFFLINE:
+      return;
+    default:
+      break;
+  }
+
+  /* Restart timer for this message */
+  restart_timeout(inst, get_transmit_delay(inst, 1));
+
+  /* If a client packet was just sent, schedule a timeout to close the socket
+     at the time when all server replies would fail the delay test, so the
+     socket is not open for longer than necessary */
+  if (inst->mode == MODE_CLIENT)
+    inst->rx_timeout_id = SCH_AddTimeoutByDelay(inst->max_delay + MAX_SERVER_INTERVAL,
+                                                receive_timeout, (void *)inst);
+}
+
+/* ================================================== */
+
+static int
+is_zero_data(unsigned char *data, int length)
+{
+  int i;
+
+  for (i = 0; i < length; i++)
+    if (data[i] != 0)
+      return 0;
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_packet(NTP_Packet *packet, int length, NTP_PacketInfo *info)
+{
+  int parsed, remainder, ef_length, ef_type, ef_body_length;
+  unsigned char *data;
+  void *ef_body;
+
+  if (length < NTP_HEADER_LENGTH || length % 4U != 0) {
+    DEBUG_LOG("NTP packet has invalid length %d", length);
+    return 0;
+  }
+
+  info->length = length;
+  info->version = NTP_LVM_TO_VERSION(packet->lvm);
+  info->mode = NTP_LVM_TO_MODE(packet->lvm);
+  info->ext_fields = 0;
+  info->ext_field_flags = 0;
+  info->auth.mode = NTP_AUTH_NONE;
+
+  if (info->version < NTP_MIN_COMPAT_VERSION || info->version > NTP_MAX_COMPAT_VERSION) {
+    DEBUG_LOG("NTP packet has invalid version %d", info->version);
+    return 0;
+  }
+
+  data = (void *)packet;
+  parsed = NTP_HEADER_LENGTH;
+  remainder = info->length - parsed;
+
+  /* Check if this is a plain NTP packet with no extension fields or MAC */
+  if (remainder <= 0)
+    return 1;
+
+  assert(remainder % 4 == 0);
+
+  /* In NTPv3 and older packets don't have extension fields.  Anything after
+     the header is assumed to be a MAC. */
+  if (info->version <= 3) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
+
+    /* Check if it is an MS-SNTP authenticator field or extended authenticator
+       field with zeroes as digest */
+    if (info->version == 3 && info->auth.mac.key_id != 0) {
+      if (remainder == 20 && is_zero_data(data + parsed + 4, remainder - 4))
+        info->auth.mode = NTP_AUTH_MSSNTP;
+      else if (remainder == 72 && is_zero_data(data + parsed + 8, remainder - 8))
+        info->auth.mode = NTP_AUTH_MSSNTP_EXT;
+    }
+
+    return 1;
+  }
+
+  /* Check for a crypto NAK */
+  if (remainder == 4 && ntohl(*(uint32_t *)(data + parsed)) == 0) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = 0;
+    return 1;
+  }
+
+  /* Parse the rest of the NTPv4 packet */
+
+  while (remainder > 0) {
+    /* Check if the remaining data is a MAC */
+    if (remainder >= NTP_MIN_MAC_LENGTH && remainder <= NTP_MAX_V4_MAC_LENGTH)
+      break;
+
+    /* Check if this is a valid NTPv4 extension field and skip it */
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length)) {
+      DEBUG_LOG("Invalid format");
+      return 0;
+    }
+
+    assert(ef_length > 0 && ef_length % 4 == 0);
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+      case NTP_EF_NTS_COOKIE:
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        info->auth.mode = NTP_AUTH_NTS;
+        break;
+      case NTP_EF_EXP1:
+        if (ef_body_length == sizeof (NTP_ExtFieldExp1) &&
+            ntohl(((NTP_ExtFieldExp1 *)ef_body)->magic) == NTP_EF_EXP1_MAGIC)
+          info->ext_field_flags |= NTP_EF_FLAG_EXP1;
+        break;
+      default:
+        DEBUG_LOG("Unknown extension field type=%x", (unsigned int)ef_type);
+    }
+
+    info->ext_fields++;
+    parsed += ef_length;
+    remainder = info->length - parsed;
+  }
+
+  if (remainder == 0) {
+    /* No MAC */
+    return 1;
+  } else if (remainder >= NTP_MIN_MAC_LENGTH) {
+    info->auth.mode = NTP_AUTH_SYMMETRIC;
+    info->auth.mac.start = parsed;
+    info->auth.mac.length = remainder;
+    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
+    return 1;
+  }
+
+  DEBUG_LOG("Invalid format");
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_ratio(NCR_Instance inst, SST_Stats stats,
+                struct timespec *sample_time, double delay)
+{
+  double last_sample_ago, predicted_offset, min_delay, skew, std_dev;
+  double max_delay;
+
+  if (inst->max_delay_ratio < 1.0 ||
+      !SST_GetDelayTestData(stats, sample_time, &last_sample_ago,
+                            &predicted_offset, &min_delay, &skew, &std_dev))
+    return 1;
+
+  max_delay = min_delay * inst->max_delay_ratio +
+              last_sample_ago * (skew + LCL_GetMaxClockError());
+
+  if (delay <= max_delay)
+    return 1;
+
+  DEBUG_LOG("maxdelayratio: delay=%e max_delay=%e", delay, max_delay);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_quant(NCR_Instance inst, double delay)
+{
+  double quant;
+
+  quant = QNT_GetQuantile(inst->delay_quant, QNT_GetMinK(inst->delay_quant));
+
+  if (delay <= quant)
+    return 1;
+
+  DEBUG_LOG("maxdelayquant: delay=%e quant=%e", delay, quant);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_delay_dev_ratio(NCR_Instance inst, SST_Stats stats,
+                      struct timespec *sample_time, double offset, double delay)
+{
+  double last_sample_ago, predicted_offset, min_delay, skew, std_dev;
+  double delta, max_delta, error_in_estimate;
+
+  if (!SST_GetDelayTestData(stats, sample_time, &last_sample_ago,
+                            &predicted_offset, &min_delay, &skew, &std_dev))
+    return 1;
+
+  /* Require that the ratio of the increase in delay from the minimum to the
+     standard deviation is less than max_delay_dev_ratio.  In the allowed
+     increase in delay include also dispersion. */
+
+  max_delta = std_dev * inst->max_delay_dev_ratio +
+              last_sample_ago * (skew + LCL_GetMaxClockError());
+  delta = (delay - min_delay) / 2.0;
+
+  if (delta <= max_delta)
+    return 1;
+
+  error_in_estimate = offset + predicted_offset;
+
+  /* Before we decide to drop the sample, make sure the difference between
+     measured offset and predicted offset is not significantly larger than
+     the increase in delay */
+  if (fabs(error_in_estimate) - delta > max_delta)
+    return 1;
+
+  DEBUG_LOG("maxdelaydevratio: error=%e delay=%e delta=%e max_delta=%e",
+            error_in_estimate, delay, delta, max_delta);
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+check_sync_loop(NCR_Instance inst, NTP_Packet *message, NTP_Local_Address *local_addr,
+                struct timespec *local_ts)
+{
+  double our_root_delay, our_root_dispersion;
+  int are_we_synchronised, our_stratum;
+  struct timespec our_ref_time;
+  NTP_Leap leap_status;
+  uint32_t our_ref_id;
+
+  /* Check if a client or peer can be synchronised to us */
+  if (!NIO_IsServerSocketOpen() || REF_GetMode() != REF_ModeNormal)
+    return 1;
+
+  /* Check if the source indicates that it is synchronised to our address
+     (assuming it uses the same address as the one from which we send requests
+     to the source) */
+  if (message->stratum > 1 &&
+      message->reference_id == htonl(UTI_IPToRefid(&local_addr->ip_addr)))
+    return 0;
+
+  /* Compare our reference data with the source to make sure it is not us
+     (e.g. due to a misconfiguration) */
+
+  REF_GetReferenceParams(local_ts, &are_we_synchronised, &leap_status, &our_stratum,
+                         &our_ref_id, &our_ref_time, &our_root_delay, &our_root_dispersion);
+
+  if (message->stratum == our_stratum &&
+      message->reference_id == htonl(our_ref_id) &&
+      message->root_delay == UTI_DoubleToNtp32(our_root_delay) &&
+      !UTI_IsZeroNtp64(&message->reference_ts)) {
+    NTP_int64 ntp_ref_time;
+
+    UTI_TimespecToNtp64(&our_ref_time, &ntp_ref_time, NULL);
+    if (UTI_CompareNtp64(&message->reference_ts, &ntp_ref_time) == 0) {
+      DEBUG_LOG("Source %s is me", UTI_IPToString(&inst->remote_addr.ip_addr));
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_sample(NCR_Instance inst, NTP_Sample *sample)
+{
+  double estimated_offset, error_in_estimate;
+  NTP_Sample filtered_sample;
+
+  /* Accumulate the sample to the median filter if enabled and wait for
+     the configured number of samples before processing (NULL indicates
+     a missing sample) */
+  if (inst->filter) {
+    if (sample)
+      SPF_AccumulateSample(inst->filter, sample);
+
+    if (++inst->filter_count < SPF_GetMaxSamples(inst->filter))
+      return;
+
+    if (!SPF_GetFilteredSample(inst->filter, &filtered_sample))
+      return;
+
+    sample = &filtered_sample;
+    inst->filter_count = 0;
+  }
+
+  if (!sample)
+    return;
+
+  /* Get the estimated offset predicted from previous samples.  The
+     convention here is that positive means local clock FAST of
+     reference, i.e. backwards to the way that 'offset' is defined. */
+  estimated_offset = SST_PredictOffset(SRC_GetSourcestats(inst->source), &sample->time);
+
+  error_in_estimate = fabs(-sample->offset - estimated_offset);
+
+  if (inst->mono_doffset != 0.0 && fabs(inst->mono_doffset) <= MAX_MONO_DOFFSET) {
+    DEBUG_LOG("Monotonic correction offset=%.9f", inst->mono_doffset);
+    SST_CorrectOffset(SRC_GetSourcestats(inst->source), inst->mono_doffset);
+  }
+  inst->mono_doffset = 0.0;
+
+  SRC_AccumulateSample(inst->source, sample);
+  SRC_SelectSource(inst->source);
+
+  adjust_poll(inst, get_poll_adj(inst, error_in_estimate,
+                                 sample->peer_dispersion + 0.5 * sample->peer_delay));
+}
+
+/* ================================================== */
+
+static int
+has_saved_response(NCR_Instance inst)
+{
+  return inst->saved_response && inst->saved_response->timeout_id > 0;
+}
+
+/* ================================================== */
+
+static void
+process_saved_response(NCR_Instance inst)
+{
+  SCH_RemoveTimeout(inst->saved_response->timeout_id);
+  inst->saved_response->timeout_id = 0;
+
+  DEBUG_LOG("Processing saved response from %s", UTI_IPToString(&inst->remote_addr.ip_addr));
+  process_response(inst, 1, &inst->saved_response->local_addr, &inst->saved_response->rx_ts,
+                   &inst->saved_response->message, &inst->saved_response->info);
+}
+
+/* ================================================== */
+
+static void
+saved_response_timeout(void *arg)
+{
+  NCR_Instance inst = arg;
+
+  inst->saved_response->timeout_id = 0;
+  process_saved_response(inst);
+}
+
+/* ================================================== */
+
+static int
+save_response(NCR_Instance inst, NTP_Local_Address *local_addr,
+              NTP_Local_Timestamp *rx_ts, NTP_Packet *message, NTP_PacketInfo *info)
+{
+  double timeout = CNF_GetHwTsTimeout();
+
+  if (timeout <= 0.0)
+    return 0;
+
+  /* If another message is already saved, process both immediately */
+  if (has_saved_response(inst)) {
+    process_saved_response(inst);
+    return 0;
+  }
+
+  if (!inst->saved_response)
+    inst->saved_response = MallocNew(struct SavedResponse);
+  inst->saved_response->local_addr = *local_addr;
+  inst->saved_response->rx_ts = *rx_ts;
+  inst->saved_response->message = *message;
+  inst->saved_response->info = *info;
+  inst->saved_response->timeout_id = SCH_AddTimeoutByDelay(timeout, saved_response_timeout,
+                                                           inst);
+  DEBUG_LOG("Saved valid response for later processing");
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_response(NCR_Instance inst, int saved, NTP_Local_Address *local_addr,
+                 NTP_Local_Timestamp *rx_ts, NTP_Packet *message, NTP_PacketInfo *info)
+{
+  NTP_Sample sample;
+  SST_Stats stats;
+
+  int pkt_leap, pkt_version;
+  uint32_t pkt_refid;
+  double pkt_root_delay;
+  double pkt_root_dispersion;
+
+  /* The skew and estimated frequency offset relative to the remote source */
+  double skew, source_freq_lo, source_freq_hi;
+
+  /* RFC 5905 packet tests */
+  int test1, test2n, test2i, test2, test3, test5, test6, test7;
+  int interleaved_packet, valid_packet, synced_packet;
+
+  /* Additional tests */
+  int testA, testB, testC, testD;
+  int good_packet;
+
+  /* Kiss-o'-Death codes */
+  int kod_rate;
+
+  /* Extension fields */
+  int parsed, ef_length, ef_type, ef_body_length;
+  void *ef_body;
+  NTP_ExtFieldExp1 *ef_exp1;
+
+  NTP_Local_Timestamp local_receive, local_transmit;
+  double remote_interval, local_interval, response_time;
+  double delay_time, precision, mono_doffset;
+  int updated_timestamps;
+
+  /* ==================== */
+
+  stats = SRC_GetSourcestats(inst->source);
+
+  ef_exp1 = NULL;
+
+  /* Find requested non-authentication extension fields */
+  if (inst->ext_field_flags & info->ext_field_flags) {
+    for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+      if (!NEF_ParseField(message, info->length, parsed,
+                          &ef_length, &ef_type, &ef_body, &ef_body_length))
+        break;
+
+      switch (ef_type) {
+        case NTP_EF_EXP1:
+          if (inst->ext_field_flags & NTP_EF_FLAG_EXP1 &&
+              ef_body_length == sizeof (*ef_exp1) &&
+              ntohl(((NTP_ExtFieldExp1 *)ef_body)->magic) == NTP_EF_EXP1_MAGIC)
+            ef_exp1 = ef_body;
+          break;
+      }
+    }
+  }
+
+  pkt_leap = NTP_LVM_TO_LEAP(message->lvm);
+  pkt_version = NTP_LVM_TO_VERSION(message->lvm);
+  pkt_refid = ntohl(message->reference_id);
+  if (ef_exp1) {
+    pkt_root_delay = UTI_Ntp32f28ToDouble(ef_exp1->root_delay);
+    pkt_root_dispersion = UTI_Ntp32f28ToDouble(ef_exp1->root_dispersion);
+  } else {
+    pkt_root_delay = UTI_Ntp32ToDouble(message->root_delay);
+    pkt_root_dispersion = UTI_Ntp32ToDouble(message->root_dispersion);
+  }
+
+  /* Check if the packet is valid per RFC 5905, section 8.
+     The test values are 1 when passed and 0 when failed. */
+  
+  /* Test 1 checks for duplicate packet */
+  test1 = UTI_CompareNtp64(&message->receive_ts, &inst->remote_ntp_rx) ||
+          UTI_CompareNtp64(&message->transmit_ts, &inst->remote_ntp_tx);
+
+  /* Test 2 checks for bogus packet in the basic and interleaved modes.  This
+     ensures the source is responding to the latest packet we sent to it. */
+  test2n = !UTI_CompareNtp64(&message->originate_ts, &inst->local_ntp_tx);
+  test2i = inst->interleaved &&
+           !UTI_CompareNtp64(&message->originate_ts, &inst->local_ntp_rx);
+  test2 = test2n || test2i;
+  interleaved_packet = !test2n && test2i;
+  
+  /* Test 3 checks for invalid timestamps.  This can happen when the
+     association if not properly 'up'. */
+  test3 = !UTI_IsZeroNtp64(&message->originate_ts) &&
+          !UTI_IsZeroNtp64(&message->receive_ts) &&
+          !UTI_IsZeroNtp64(&message->transmit_ts);
+
+  /* Test 4 would check for denied access.  It would always pass as this
+     function is called only for known sources. */
+
+  /* Test 5 checks for authentication failure.  If it is a saved message,
+     which had to pass all these tests before, avoid authenticating it for
+     the second time (that is not allowed in the NTS code). */
+  test5 = saved || NAU_CheckResponseAuth(inst->auth, message, info);
+
+  /* Test 6 checks for unsynchronised server */
+  test6 = pkt_leap != LEAP_Unsynchronised &&
+          message->stratum < NTP_MAX_STRATUM &&
+          message->stratum != NTP_INVALID_STRATUM; 
+
+  /* Test 7 checks for bad data.  The root distance must be smaller than a
+     defined maximum. */
+  test7 = pkt_root_delay / 2.0 + pkt_root_dispersion < NTP_MAX_DISPERSION;
+
+  /* The packet is considered valid if the tests 1-5 passed.  The timestamps
+     can be used for synchronisation if the tests 6 and 7 passed too. */
+  valid_packet = test1 && test2 && test3 && test5;
+  synced_packet = valid_packet && test6 && test7;
+
+  /* If the server is very close and/or the NIC hardware/driver is slow, it
+     is possible that a response from the server is received before the HW
+     transmit timestamp of the request.  To avoid getting a less accurate
+     offset or failing one of the later tests, save the response and wait for
+     the transmit timestamp or timeout.  Allow this only for the first valid
+     response to the request, when at least one good response has already been
+     accepted to avoid incorrectly confirming a tentative source. */
+  if (valid_packet && synced_packet && !saved && !inst->valid_rx &&
+      NIO_IsHwTsEnabled() && inst->local_tx.source != NTP_TS_HARDWARE &&
+      inst->report.total_good_count > 0) {
+    if (save_response(inst, local_addr, rx_ts, message, info))
+      return 1;
+  }
+
+  /* Check for Kiss-o'-Death codes */
+  kod_rate = 0;
+  if (test1 && test2 && test5 && pkt_leap == LEAP_Unsynchronised &&
+      message->stratum == NTP_INVALID_STRATUM) {
+    if (pkt_refid == KOD_RATE)
+      kod_rate = 1;
+  }
+
+  if (synced_packet && (!interleaved_packet || inst->valid_timestamps)) {
+    /* These are the timespec equivalents of the remote and local epochs */
+    struct timespec remote_receive, remote_transmit, remote_request_receive;
+    struct timespec local_average, remote_average, prev_remote_transmit;
+    double prev_remote_poll_interval, root_delay, root_dispersion;
+
+    /* If the remote monotonic timestamps are available and are from the same
+       epoch, calculate the change in the offset between the monotonic and
+       real-time clocks, i.e. separate the source's time corrections from
+       frequency corrections.  The offset is accumulated between measurements.
+       It will correct old measurements kept in sourcestats before accumulating
+       the new sample.  In the interleaved mode, cancel the correction out in
+       remote timestamps of the previous request and response, which were
+       captured before the source accumulated the new time corrections. */
+    if (ef_exp1 && inst->remote_mono_epoch == ntohl(ef_exp1->mono_epoch) &&
+        !UTI_IsZeroNtp64(&ef_exp1->mono_receive_ts) &&
+        !UTI_IsZeroNtp64(&inst->remote_ntp_monorx)) {
+      mono_doffset =
+          UTI_DiffNtp64ToDouble(&ef_exp1->mono_receive_ts, &inst->remote_ntp_monorx) -
+          UTI_DiffNtp64ToDouble(&message->receive_ts, &inst->remote_ntp_rx);
+      if (fabs(mono_doffset) > MAX_MONO_DOFFSET)
+        mono_doffset = 0.0;
+    } else {
+      mono_doffset = 0.0;
+    }
+
+    /* Select remote and local timestamps for the new sample */
+    if (interleaved_packet) {
+      /* Prefer previous local TX and remote RX timestamps if it will make
+         the intervals significantly shorter in order to improve the accuracy
+         of the measured delay */
+      if (!UTI_IsZeroTimespec(&inst->prev_local_tx.ts) &&
+          MAX_INTERLEAVED_L2L_RATIO *
+            UTI_DiffTimespecsToDouble(&inst->local_tx.ts, &inst->local_rx.ts) >
+          UTI_DiffTimespecsToDouble(&inst->local_rx.ts, &inst->prev_local_tx.ts)) {
+        UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &remote_receive);
+        UTI_AddDoubleToTimespec(&remote_receive, -mono_doffset, &remote_receive);
+        remote_request_receive = remote_receive;
+        local_transmit = inst->prev_local_tx;
+        root_delay = inst->remote_root_delay;
+        root_dispersion = inst->remote_root_dispersion;
+      } else {
+        UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
+        UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &remote_request_receive);
+        local_transmit = inst->local_tx;
+        root_delay = MAX(pkt_root_delay, inst->remote_root_delay);
+        root_dispersion = MAX(pkt_root_dispersion, inst->remote_root_dispersion);
+      }
+      UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
+      UTI_AddDoubleToTimespec(&remote_transmit, -mono_doffset, &remote_transmit);
+      UTI_Ntp64ToTimespec(&inst->remote_ntp_tx, &prev_remote_transmit);
+      local_receive = inst->local_rx;
+    } else {
+      UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
+      UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
+      UTI_ZeroTimespec(&prev_remote_transmit);
+      remote_request_receive = remote_receive;
+      local_receive = *rx_ts;
+      local_transmit = inst->local_tx;
+      root_delay = pkt_root_delay;
+      root_dispersion = pkt_root_dispersion;
+    }
+
+    /* Calculate intervals between remote and local timestamps */
+    UTI_AverageDiffTimespecs(&remote_receive, &remote_transmit,
+                             &remote_average, &remote_interval);
+    UTI_AverageDiffTimespecs(&local_transmit.ts, &local_receive.ts,
+                             &local_average, &local_interval);
+    response_time = fabs(UTI_DiffTimespecsToDouble(&remote_transmit,
+                                                   &remote_request_receive));
+
+    precision = LCL_GetSysPrecisionAsQuantum() + UTI_Log2ToDouble(message->precision);
+
+    /* Calculate delay */
+    sample.peer_delay = fabs(local_interval - remote_interval);
+    if (sample.peer_delay < precision)
+      sample.peer_delay = precision;
+    
+    /* Calculate offset.  Following the NTP definition, this is negative
+       if we are fast of the remote source. */
+    sample.offset = UTI_DiffTimespecsToDouble(&remote_average, &local_average);
+
+    /* Apply configured correction */
+    sample.offset += inst->offset_correction;
+
+    /* We treat the time of the sample as being midway through the local
+       measurement period.  An analysis assuming constant relative
+       frequency and zero network delay shows this is the only possible
+       choice to estimate the frequency difference correctly for every
+       sample pair. */
+    sample.time = local_average;
+    
+    SST_GetFrequencyRange(stats, &source_freq_lo, &source_freq_hi);
+
+    /* Calculate skew */
+    skew = (source_freq_hi - source_freq_lo) / 2.0;
+    
+    /* and then calculate peer dispersion and the rest of the sample */
+    sample.peer_dispersion = MAX(precision, MAX(local_transmit.err, local_receive.err)) +
+                             skew * fabs(local_interval);
+    sample.root_delay = root_delay + sample.peer_delay;
+    sample.root_dispersion = root_dispersion + sample.peer_dispersion;
+    
+    /* If the source is an active peer, this is the minimum assumed interval
+       between previous two transmissions (if not constrained by minpoll) */
+    prev_remote_poll_interval = UTI_Log2ToDouble(MIN(inst->remote_poll,
+                                                     inst->prev_local_poll));
+
+    /* Additional tests required to pass before accumulating the sample */
+
+    /* Test A requires that the minimum estimate of the peer delay is not
+       larger than the configured maximum, in both client modes that the server
+       processing time is sane, in interleaved client/server mode that the
+       previous response was not in basic mode (which prevents using timestamps
+       that minimise delay error), and in interleaved symmetric mode that the
+       measured delay and intervals between remote timestamps don't indicate
+       a missed response */
+    testA = sample.peer_delay - sample.peer_dispersion <= inst->max_delay &&
+            precision <= inst->max_delay &&
+            !(inst->mode == MODE_CLIENT && response_time > MAX_SERVER_INTERVAL) &&
+            !(inst->mode == MODE_CLIENT && interleaved_packet &&
+              UTI_IsZeroTimespec(&inst->prev_local_tx.ts) &&
+              UTI_CompareTimespecs(&local_transmit.ts, &inst->local_tx.ts) == 0) &&
+            !(inst->mode == MODE_ACTIVE && interleaved_packet &&
+              (sample.peer_delay > 0.5 * prev_remote_poll_interval ||
+               UTI_CompareNtp64(&message->receive_ts, &message->transmit_ts) <= 0 ||
+               (inst->remote_poll <= inst->prev_local_poll &&
+                UTI_DiffTimespecsToDouble(&remote_transmit, &prev_remote_transmit) >
+                  1.5 * prev_remote_poll_interval)));
+
+    /* Test B requires in client mode that the ratio of the round trip delay
+       to the minimum one currently in the stats data register is less than an
+       administrator-defined value */
+    testB = check_delay_ratio(inst, stats, &sample.time, sample.peer_delay);
+
+    /* Test C either requires that the delay is less than an estimate of an
+       administrator-defined quantile, or (if the quantile is not specified)
+       it requires that the ratio of the increase in delay from the minimum
+       one in the stats data register to the standard deviation of the offsets
+       in the register is less than an administrator-defined value or the
+       difference between measured offset and predicted offset is larger than
+       the increase in delay */
+    if (inst->delay_quant)
+      testC = check_delay_quant(inst, sample.peer_delay);
+    else
+      testC = check_delay_dev_ratio(inst, stats, &sample.time, sample.offset,
+                                    sample.peer_delay);
+
+    /* Test D requires that the source is not synchronised to us and is not us
+       to prevent a synchronisation loop */
+    testD = check_sync_loop(inst, message, local_addr, &rx_ts->ts);
+  } else {
+    remote_interval = local_interval = response_time = 0.0;
+    sample.offset = sample.peer_delay = sample.peer_dispersion = 0.0;
+    sample.root_delay = sample.root_dispersion = 0.0;
+    sample.time = rx_ts->ts;
+    mono_doffset = 0.0;
+    local_receive = *rx_ts;
+    local_transmit = inst->local_tx;
+    testA = testB = testC = testD = 0;
+  }
+  
+  /* The packet is considered good for synchronisation if
+     the additional tests passed */
+  good_packet = testA && testB && testC && testD;
+
+  /* Update the NTP timestamps.  If it's a valid packet from a synchronised
+     source, the timestamps may be used later when processing a packet in the
+     interleaved mode.  Protect the timestamps against replay attacks in client
+     mode, and also in symmetric mode as long as the peers use the same polling
+     interval and never start with clocks in future or very distant past.
+     The authentication test (test5) is required to prevent DoS attacks using
+     unauthenticated packets on authenticated symmetric associations. */
+  if ((inst->mode == MODE_CLIENT && valid_packet && !inst->valid_rx) ||
+      (inst->mode == MODE_ACTIVE && valid_packet &&
+       (!inst->valid_rx ||
+        UTI_CompareNtp64(&inst->remote_ntp_tx, &message->transmit_ts) < 0))) {
+    inst->remote_ntp_rx = message->receive_ts;
+    inst->remote_ntp_tx = message->transmit_ts;
+    inst->local_rx = *rx_ts;
+    inst->valid_timestamps = synced_packet;
+
+    UTI_ZeroNtp64(&inst->init_remote_ntp_tx);
+    zero_local_timestamp(&inst->init_local_rx);
+    inst->updated_init_timestamps = 0;
+    updated_timestamps = 2;
+
+    /* If available, update the monotonic timestamp and accumulate the offset.
+       This needs to be done here to not lose changes in remote_ntp_rx in
+       symmetric mode when there are multiple responses per request. */
+    if (ef_exp1 && !UTI_IsZeroNtp64(&ef_exp1->mono_receive_ts)) {
+      inst->remote_mono_epoch = ntohl(ef_exp1->mono_epoch);
+      inst->remote_ntp_monorx = ef_exp1->mono_receive_ts;
+      inst->mono_doffset += mono_doffset;
+    } else {
+      inst->remote_mono_epoch = 0;
+      UTI_ZeroNtp64(&inst->remote_ntp_monorx);
+      inst->mono_doffset = 0.0;
+    }
+
+    /* Don't use the same set of timestamps for the next sample */
+    if (interleaved_packet)
+      inst->prev_local_tx = inst->local_tx;
+    else
+      zero_local_timestamp(&inst->prev_local_tx);
+  } else if (inst->mode == MODE_ACTIVE &&
+             test1 && !UTI_IsZeroNtp64(&message->transmit_ts) && test5 &&
+             (!inst->updated_init_timestamps ||
+              UTI_CompareNtp64(&inst->init_remote_ntp_tx, &message->transmit_ts) < 0)) {
+    inst->init_remote_ntp_tx = message->transmit_ts;
+    inst->init_local_rx = *rx_ts;
+    inst->updated_init_timestamps = 1;
+    updated_timestamps = 1;
+  } else {
+    updated_timestamps = 0;
+  }
+
+  /* Accept at most one response per request.  The NTP specification recommends
+     resetting local_ntp_tx to make the following packets fail test2 or test3,
+     but that would not allow the code above to make multiple updates of the
+     timestamps in symmetric mode.  Also, ignore presend responses. */
+  if (inst->valid_rx) {
+    test2 = test3 = 0;
+    valid_packet = synced_packet = good_packet = 0;
+  } else if (valid_packet) {
+    if (inst->presend_done) {
+      testA = 0;
+      good_packet = 0;
+    }
+    inst->valid_rx = 1;
+  }
+
+  if ((unsigned int)local_receive.source >= sizeof (tss_chars) ||
+      (unsigned int)local_transmit.source >= sizeof (tss_chars))
+    assert(0);
+
+  DEBUG_LOG("NTP packet lvm=%o stratum=%d poll=%d prec=%d root_delay=%.9f root_disp=%.9f refid=%"PRIx32" [%s]",
+            message->lvm, message->stratum, message->poll, message->precision,
+            pkt_root_delay, pkt_root_dispersion, pkt_refid,
+            message->stratum == NTP_INVALID_STRATUM || message->stratum == 1 ?
+              UTI_RefidToString(pkt_refid) : "");
+  DEBUG_LOG("reference=%s origin=%s receive=%s transmit=%s",
+            UTI_Ntp64ToString(&message->reference_ts),
+            UTI_Ntp64ToString(&message->originate_ts),
+            UTI_Ntp64ToString(&message->receive_ts),
+            UTI_Ntp64ToString(&message->transmit_ts));
+  DEBUG_LOG("offset=%.9f delay=%.9f dispersion=%f root_delay=%f root_dispersion=%f",
+            sample.offset, sample.peer_delay, sample.peer_dispersion,
+            sample.root_delay, sample.root_dispersion);
+  DEBUG_LOG("remote_interval=%.9f local_interval=%.9f response_time=%.9f mono_doffset=%.9f txs=%c rxs=%c",
+            remote_interval, local_interval, response_time, mono_doffset,
+            tss_chars[local_transmit.source], tss_chars[local_receive.source]);
+  DEBUG_LOG("test123=%d%d%d test567=%d%d%d testABCD=%d%d%d%d kod_rate=%d interleaved=%d"
+            " presend=%d valid=%d good=%d updated=%d",
+            test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
+            kod_rate, interleaved_packet, inst->presend_done, valid_packet, good_packet,
+            updated_timestamps);
+
+  if (valid_packet) {
+    inst->remote_poll = message->poll;
+    inst->remote_stratum = message->stratum != NTP_INVALID_STRATUM ?
+                           MIN(message->stratum, NTP_MAX_STRATUM) : NTP_MAX_STRATUM;
+    inst->remote_root_delay = pkt_root_delay;
+    inst->remote_root_dispersion = pkt_root_dispersion;
+
+    inst->prev_local_poll = inst->local_poll;
+    inst->prev_tx_count = inst->tx_count;
+    inst->tx_count = 0;
+
+    SRC_UpdateReachability(inst->source, synced_packet);
+
+    if (synced_packet) {
+      if (inst->copy && inst->remote_stratum > 0) {
+        /* Assume the reference ID and stratum of the server */
+        inst->remote_stratum--;
+        SRC_SetRefid(inst->source, ntohl(message->reference_id), &inst->remote_addr.ip_addr);
+      }
+
+      SRC_UpdateStatus(inst->source, MAX(inst->remote_stratum, inst->min_stratum), pkt_leap);
+
+      if (inst->delay_quant)
+        QNT_Accumulate(inst->delay_quant, sample.peer_delay);
+    }
+
+    if (good_packet) {
+      /* Adjust the polling interval, accumulate the sample, etc. */
+      process_sample(inst, &sample);
+
+      /* If we're in burst mode, check whether the burst is completed and
+         revert to the previous mode */
+      switch (inst->opmode) {
+        case MD_BURST_WAS_ONLINE:
+        case MD_BURST_WAS_OFFLINE:
+          --inst->burst_good_samples_to_go;
+          if (inst->burst_good_samples_to_go <= 0) {
+            if (inst->opmode == MD_BURST_WAS_ONLINE)
+              inst->opmode = MD_ONLINE;
+            else
+              take_offline(inst);
+          }
+          break;
+        default:
+          break;
+      }
+    } else {
+      /* Slowly increase the polling interval if we can't get a good response */
+      adjust_poll(inst, testD ? 0.02 : 0.1);
+
+      /* Count missing samples for the sample filter */
+      process_sample(inst, NULL);
+    }
+
+    /* If in client mode, no more packets are expected to be coming from the
+       server and the socket can be closed */
+    close_client_socket(inst);
+
+    /* Update the local address and interface */
+    inst->local_addr.ip_addr = local_addr->ip_addr;
+    inst->local_addr.if_index = local_addr->if_index;
+
+    /* And now, requeue the timer */
+    if (inst->opmode != MD_OFFLINE) {
+      delay_time = get_transmit_delay(inst, 0);
+
+      if (kod_rate) {
+        LOG(LOGS_WARN, "Received KoD RATE from %s",
+            UTI_IPToString(&inst->remote_addr.ip_addr));
+
+        /* Back off for a while and stop ongoing burst */
+        delay_time += 4 * UTI_Log2ToDouble(inst->local_poll);
+
+        if (inst->opmode == MD_BURST_WAS_OFFLINE || inst->opmode == MD_BURST_WAS_ONLINE) {
+          inst->burst_good_samples_to_go = 0;
+        }
+      }
+
+      /* Get rid of old timeout and start a new one */
+      if (!saved)
+        assert(inst->tx_timeout_id);
+      restart_timeout(inst, delay_time);
+    }
+
+    /* Update the NTP report */
+    inst->report.local_addr = inst->local_addr.ip_addr;
+    inst->report.leap = pkt_leap;
+    inst->report.version = pkt_version;
+    inst->report.mode = NTP_LVM_TO_MODE(message->lvm);
+    inst->report.stratum = message->stratum;
+    inst->report.poll = message->poll;
+    inst->report.precision = message->precision;
+    inst->report.root_delay = pkt_root_delay;
+    inst->report.root_dispersion = pkt_root_dispersion;
+    inst->report.ref_id = pkt_refid;
+    UTI_Ntp64ToTimespec(&message->reference_ts, &inst->report.ref_time);
+    inst->report.offset = sample.offset;
+    inst->report.peer_delay = sample.peer_delay;
+    inst->report.peer_dispersion = sample.peer_dispersion;
+    inst->report.response_time = response_time;
+    inst->report.jitter_asymmetry = SST_GetJitterAsymmetry(stats);
+    inst->report.tests = ((((((((test1 << 1 | test2) << 1 | test3) << 1 |
+                               test5) << 1 | test6) << 1 | test7) << 1 |
+                            testA) << 1 | testB) << 1 | testC) << 1 | testD;
+    inst->report.interleaved = interleaved_packet;
+    inst->report.authenticated = NAU_IsAuthEnabled(inst->auth);
+    inst->report.tx_tss_char = tss_chars[local_transmit.source];
+    inst->report.rx_tss_char = tss_chars[local_receive.source];
+
+    inst->report.total_valid_count++;
+    if (good_packet)
+      inst->report.total_good_count++;
+  }
+
+  /* Do measurement logging */
+  if (logfileid != -1 && (log_raw_measurements || synced_packet)) {
+    LOG_FileWrite(logfileid, "%s %-15s %1c %2d %1d%1d%1d %1d%1d%1d %1d%1d%1d%d  %2d %2d %4.2f %10.3e %10.3e %10.3e %10.3e %10.3e %08"PRIX32" %1d%1c %1c %1c",
+            UTI_TimeToLogForm(sample.time.tv_sec),
+            UTI_IPToString(&inst->remote_addr.ip_addr),
+            leap_chars[pkt_leap],
+            message->stratum,
+            test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
+            inst->local_poll, message->poll,
+            inst->poll_score,
+            sample.offset, sample.peer_delay, sample.peer_dispersion,
+            pkt_root_delay, pkt_root_dispersion, pkt_refid,
+            NTP_LVM_TO_MODE(message->lvm), interleaved_packet ? 'I' : 'B',
+            tss_chars[local_transmit.source],
+            tss_chars[local_receive.source]);
+  }            
+
+  return good_packet;
+}
+
+/* ================================================== */
+/* From RFC 5905, the standard handling of received packets, depending
+   on the mode of the packet and of the source, is :
+
+   +------------------+---------------------------------------+
+   |                  |              Packet Mode              |
+   +------------------+-------+-------+-------+-------+-------+
+   | Association Mode |   1   |   2   |   3   |   4   |   5   |
+   +------------------+-------+-------+-------+-------+-------+
+   | No Association 0 | NEWPS | DSCRD | FXMIT | MANY  | NEWBC |
+   | Symm. Active   1 | PROC  | PROC  | DSCRD | DSCRD | DSCRD |
+   | Symm. Passive  2 | PROC  | ERR   | DSCRD | DSCRD | DSCRD |
+   | Client         3 | DSCRD | DSCRD | DSCRD | PROC  | DSCRD |
+   | Server         4 | DSCRD | DSCRD | DSCRD | DSCRD | DSCRD |
+   | Broadcast      5 | DSCRD | DSCRD | DSCRD | DSCRD | DSCRD |
+   | Bcast Client   6 | DSCRD | DSCRD | DSCRD | DSCRD | PROC  |
+   +------------------+-------+-------+-------+-------+-------+
+
+   Association mode 0 is implemented in NCR_ProcessRxUnknown(), other modes
+   in NCR_ProcessRxKnown().
+
+   Broadcast, manycast and ephemeral symmetric passive associations are not
+   supported yet.
+ */
+
+/* ================================================== */
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we have an ongoing protocol exchange with */
+
+int
+NCR_ProcessRxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                   NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  int proc_packet, proc_as_unknown;
+  NTP_PacketInfo info;
+
+  inst->report.total_rx_count++;
+
+  if (!parse_packet(message, length, &info))
+    return 0;
+
+  proc_packet = 0;
+  proc_as_unknown = 0;
+
+  /* Now, depending on the mode we decide what to do */
+  switch (info.mode) {
+    case MODE_ACTIVE:
+      switch (inst->mode) {
+        case MODE_ACTIVE:
+          /* Ordinary symmetric peering */
+          proc_packet = 1;
+          break;
+        case MODE_PASSIVE:
+          /* In this software this case should not arise, we don't
+             support unconfigured peers */
+          break;
+        case MODE_CLIENT:
+          /* This is where we have the remote configured as a server and he has
+             us configured as a peer, process as from an unknown source */
+          proc_as_unknown = 1;
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_PASSIVE:
+      switch (inst->mode) {
+        case MODE_ACTIVE:
+          /* This would arise if we have the remote configured as a peer and
+             he does not have us configured */
+          proc_packet = 1;
+          break;
+        case MODE_PASSIVE:
+          /* Error condition in RFC 5905 */
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_CLIENT:
+      /* If message is client mode, we just respond with a server mode
+         packet, regardless of what we think the remote machine is
+         supposed to be.  However, even though this is a configured
+         peer or server, we still implement access restrictions on
+         client mode operation.
+
+         This copes with the case for an isolated network where one
+         machine is set by eye and is used as the primary server, with
+         the other machines pointed at it.  If the server goes down, we
+         want to be able to reset its time at startup by relying on
+         one of the secondaries to flywheel it. The behaviour coded here
+         is required in the secondaries to make this possible. */
+
+      proc_as_unknown = 1;
+      break;
+
+    case MODE_SERVER:
+      switch (inst->mode) {
+        case MODE_CLIENT:
+          /* Standard case where he's a server and we're the client */
+          proc_packet = 1;
+          break;
+        default:
+          /* Discard */
+          break;
+      }
+      break;
+
+    case MODE_BROADCAST:
+      /* Just ignore these */
+      break;
+
+    default:
+      /* Obviously ignore */
+      break;
+  }
+
+  if (proc_packet) {
+    /* Check if the reply was received by the socket that sent the request */
+    if (local_addr->sock_fd != inst->local_addr.sock_fd) {
+      DEBUG_LOG("Packet received by wrong socket %d (expected %d)",
+                local_addr->sock_fd, inst->local_addr.sock_fd);
+      return 0;
+    }
+
+    /* Ignore packets from offline sources */
+    if (inst->opmode == MD_OFFLINE || inst->tx_suspended) {
+      DEBUG_LOG("Packet from offline source");
+      return 0;
+    }
+
+    return process_response(inst, 0, local_addr, rx_ts, message, &info);
+  } else if (proc_as_unknown) {
+    NCR_ProcessRxUnknown(&inst->remote_addr, local_addr, rx_ts, message, length);
+    /* It's not a reply to our request, don't return success */
+    return 0;
+  } else {
+    DEBUG_LOG("NTP packet discarded mode=%d our_mode=%u", (int)info.mode, inst->mode);
+    return 0;
+  }
+}
+
+/* ================================================== */
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we don't know (not our server or peer) */
+
+void
+NCR_ProcessRxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                     NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  NTP_PacketInfo info;
+  NTP_Mode my_mode;
+  NTP_Local_Timestamp local_tx, *tx_ts;
+  NTP_int64 ntp_rx, *local_ntp_rx;
+  int log_index, interleaved, poll, version;
+  uint32_t kod;
+
+  /* Ignore the packet if it wasn't received by server socket */
+  if (!NIO_IsServerSocket(local_addr->sock_fd)) {
+    DEBUG_LOG("NTP request packet received by client socket %d", local_addr->sock_fd);
+    return;
+  }
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  if (!ADF_IsAllowed(access_auth_table, &remote_addr->ip_addr)) {
+    DEBUG_LOG("NTP packet received from unauthorised host %s",
+              UTI_IPToString(&remote_addr->ip_addr));
+    return;
+  }
+
+  switch (info.mode) {
+    case MODE_ACTIVE:
+      /* We are symmetric passive, even though we don't ever lock to him */
+      my_mode = MODE_PASSIVE;
+      break;
+    case MODE_CLIENT:
+      /* Reply with server packet */
+      my_mode = MODE_SERVER;
+      break;
+    case MODE_UNDEFINED:
+      /* Check if it is an NTPv1 client request (NTPv1 packets have a reserved
+         field instead of the mode field and the actual mode is determined from
+         the port numbers).  Don't ever respond with a mode 0 packet! */
+      if (info.version == 1 && remote_addr->port != NTP_PORT) {
+        my_mode = MODE_SERVER;
+        break;
+      }
+      /* Fall through */
+    default:
+      /* Discard */
+      DEBUG_LOG("NTP packet discarded mode=%d", (int)info.mode);
+      return;
+  }
+
+  kod = 0;
+  log_index = CLG_LogServiceAccess(CLG_NTP, &remote_addr->ip_addr, &rx_ts->ts);
+
+  /* Don't reply to all requests if the rate is excessive */
+  if (log_index >= 0 && CLG_LimitServiceRate(CLG_NTP, log_index)) {
+      DEBUG_LOG("NTP packet discarded to limit response rate");
+      return;
+  }
+
+  /* Check authentication */
+  if (!NAU_CheckRequestAuth(message, &info, &kod)) {
+    DEBUG_LOG("NTP packet failed auth mode=%d kod=%"PRIx32, (int)info.auth.mode, kod);
+
+    /* Don't respond unless a non-zero KoD was returned */
+    if (kod == 0)
+      return;
+  }
+
+  local_ntp_rx = NULL;
+  tx_ts = NULL;
+  interleaved = 0;
+
+  /* Handle requests formed in the interleaved mode.  As an optimisation to
+     avoid saving all receive timestamps, require that the origin timestamp
+     has the lowest bit equal to 1, which indicates it was set to one of our
+     receive timestamps instead of transmit timestamps or zero.  Respond in the
+     interleaved mode if the receive timestamp is found and it has a non-zero
+     transmit timestamp (this is verified in transmit_packet()).  For a new
+     client starting with a zero origin timestamp, the third response is the
+     earliest one that can be interleaved. */
+  if (kod == 0 && log_index >= 0 && info.version == 4 &&
+      message->originate_ts.lo & htonl(1) &&
+      UTI_CompareNtp64(&message->receive_ts, &message->transmit_ts) != 0) {
+    ntp_rx = message->originate_ts;
+    local_ntp_rx = &ntp_rx;
+    UTI_ZeroTimespec(&local_tx.ts);
+    local_tx.source = NTP_TS_DAEMON;
+    interleaved = CLG_GetNtpTxTimestamp(&ntp_rx, &local_tx.ts, &local_tx.source);
+
+    tx_ts = &local_tx;
+    if (interleaved)
+      CLG_DisableNtpTimestamps(&ntp_rx);
+  }
+
+  CLG_UpdateNtpStats(kod != 0 && info.auth.mode != NTP_AUTH_NONE &&
+                     info.auth.mode != NTP_AUTH_MSSNTP,
+                     rx_ts->source, interleaved ? tx_ts->source : NTP_TS_DAEMON);
+
+  /* Suggest the client to increase its polling interval if it indicates
+     the interval is shorter than the rate limiting interval */
+  poll = CLG_GetNtpMinPoll();
+  poll = MAX(poll, message->poll);
+
+  /* Respond with the same version */
+  version = info.version;
+
+  /* Send a reply */
+  if (!transmit_packet(my_mode, interleaved, poll, version, kod, info.ext_field_flags, NULL,
+                       &message->receive_ts, &message->transmit_ts,
+                       rx_ts, tx_ts, local_ntp_rx, NULL, remote_addr, local_addr,
+                       message, &info))
+    return;
+
+  if (local_ntp_rx)
+    CLG_SaveNtpTimestamps(local_ntp_rx, &tx_ts->ts, tx_ts->source);
+}
+
+/* ================================================== */
+
+static void
+update_tx_timestamp(NTP_Local_Timestamp *tx_ts, NTP_Local_Timestamp *new_tx_ts,
+                    NTP_int64 *local_ntp_rx, NTP_int64 *local_ntp_tx, NTP_Packet *message)
+{
+  double delay;
+
+  if (UTI_IsZeroTimespec(&tx_ts->ts)) {
+    DEBUG_LOG("Unexpected TX update");
+    return;
+  }
+
+  /* Check if this is the last packet that was sent */
+  if ((local_ntp_rx && UTI_CompareNtp64(&message->receive_ts, local_ntp_rx)) ||
+      (local_ntp_tx && UTI_CompareNtp64(&message->transmit_ts, local_ntp_tx))) {
+    DEBUG_LOG("RX/TX timestamp mismatch");
+    return;
+  }
+
+  delay = UTI_DiffTimespecsToDouble(&new_tx_ts->ts, &tx_ts->ts);
+
+  if (delay < 0.0 || delay > MAX_TX_DELAY) {
+    DEBUG_LOG("Unacceptable TX delay %.9f", delay);
+    return;
+  }
+
+  *tx_ts = *new_tx_ts;
+
+  DEBUG_LOG("Updated TX timestamp delay=%.9f", delay);
+}
+
+/* ================================================== */
+
+void
+NCR_ProcessTxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                   NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  NTP_PacketInfo info;
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  /* Server and passive mode packets are responses to unknown sources */
+  if (info.mode != MODE_CLIENT && info.mode != MODE_ACTIVE) {
+    NCR_ProcessTxUnknown(&inst->remote_addr, local_addr, tx_ts, message, length);
+    return;
+  }
+
+  update_tx_timestamp(&inst->local_tx, tx_ts, &inst->local_ntp_rx, &inst->local_ntp_tx,
+                      message);
+
+  if (tx_ts->source == NTP_TS_HARDWARE) {
+    if (has_saved_response(inst))
+      process_saved_response(inst);
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                     NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  NTP_Local_Timestamp old_tx, new_tx;
+  NTP_int64 *local_ntp_rx;
+  NTP_PacketInfo info;
+
+  if (!parse_packet(message, length, &info))
+    return;
+
+  if (info.mode == MODE_BROADCAST)
+    return;
+
+  if (SMT_IsEnabled() && info.mode == MODE_SERVER)
+    UTI_AddDoubleToTimespec(&tx_ts->ts, SMT_GetOffset(&tx_ts->ts), &tx_ts->ts);
+
+  local_ntp_rx = &message->receive_ts;
+  new_tx = *tx_ts;
+
+  if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &old_tx.ts, &old_tx.source))
+    return;
+
+  /* Undo a clock adjustment between the RX and TX timestamps to minimise error
+     in the delay measured by the client */
+  CLG_UndoNtpTxTimestampSlew(local_ntp_rx, &new_tx.ts);
+
+  update_tx_timestamp(&old_tx, &new_tx, local_ntp_rx, NULL, message);
+
+  CLG_UpdateNtpTxTimestamp(local_ntp_rx, &new_tx.ts, new_tx.source);
+}
+
+/* ================================================== */
+
+void
+NCR_SlewTimes(NCR_Instance inst, struct timespec *when, double dfreq, double doffset)
+{
+  double delta;
+
+  if (!UTI_IsZeroTimespec(&inst->local_rx.ts))
+    UTI_AdjustTimespec(&inst->local_rx.ts, when, &inst->local_rx.ts, &delta, dfreq, doffset);
+  if (!UTI_IsZeroTimespec(&inst->local_tx.ts))
+    UTI_AdjustTimespec(&inst->local_tx.ts, when, &inst->local_tx.ts, &delta, dfreq, doffset);
+  if (!UTI_IsZeroTimespec(&inst->prev_local_tx.ts))
+    UTI_AdjustTimespec(&inst->prev_local_tx.ts, when, &inst->prev_local_tx.ts, &delta, dfreq,
+                       doffset);
+  if (!UTI_IsZeroTimespec(&inst->init_local_rx.ts))
+    UTI_AdjustTimespec(&inst->init_local_rx.ts, when, &inst->init_local_rx.ts, &delta, dfreq,
+                       doffset);
+
+  if (inst->filter)
+    SPF_SlewSamples(inst->filter, when, dfreq, doffset);
+
+  if (has_saved_response(inst))
+    UTI_AdjustTimespec(&inst->saved_response->rx_ts.ts, when, &inst->saved_response->rx_ts.ts,
+                       &delta, dfreq, doffset);
+}
+
+/* ================================================== */
+
+static void
+set_connectivity(NCR_Instance inst, SRC_Connectivity connectivity)
+{
+  if (connectivity == SRC_MAYBE_ONLINE)
+    connectivity = NIO_IsServerConnectable(&inst->remote_addr) ? SRC_ONLINE : SRC_OFFLINE;
+
+  switch (connectivity) {
+    case SRC_ONLINE:
+      switch (inst->opmode) {
+        case MD_ONLINE:
+          /* Nothing to do */
+          break;
+        case MD_OFFLINE:
+          inst->opmode = MD_ONLINE;
+          NCR_ResetInstance(inst);
+          start_initial_timeout(inst);
+          if (inst->auto_iburst)
+            NCR_InitiateSampleBurst(inst, IBURST_GOOD_SAMPLES, IBURST_TOTAL_SAMPLES);
+          break;
+        case MD_BURST_WAS_ONLINE:
+          /* Will revert */
+          break;
+        case MD_BURST_WAS_OFFLINE:
+          inst->opmode = MD_BURST_WAS_ONLINE;
+          break;
+        default:
+          assert(0);
+      }
+      break;
+    case SRC_OFFLINE:
+      switch (inst->opmode) {
+        case MD_ONLINE:
+          take_offline(inst);
+          break;
+        case MD_OFFLINE:
+          break;
+        case MD_BURST_WAS_ONLINE:
+          inst->opmode = MD_BURST_WAS_OFFLINE;
+          break;
+        case MD_BURST_WAS_OFFLINE:
+          break;
+        default:
+          assert(0);
+      }
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_SetConnectivity(NCR_Instance inst, SRC_Connectivity connectivity)
+{
+  OperatingMode prev_opmode;
+  int was_online, is_online;
+
+  prev_opmode = inst->opmode;
+
+  set_connectivity(inst, connectivity);
+
+  /* Report an important change */
+  was_online = prev_opmode == MD_ONLINE || prev_opmode == MD_BURST_WAS_ONLINE;
+  is_online = inst->opmode == MD_ONLINE || inst->opmode == MD_BURST_WAS_ONLINE;
+  if (was_online != is_online)
+    LOG(LOGS_INFO, "Source %s %s",
+        UTI_IPToString(&inst->remote_addr.ip_addr), is_online ? "online" : "offline");
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMinpoll(NCR_Instance inst, int new_minpoll)
+{
+  if (new_minpoll < MIN_POLL || new_minpoll > MAX_POLL)
+    return;
+  inst->minpoll = new_minpoll;
+  LOG(LOGS_INFO, "Source %s new minpoll %d", UTI_IPToString(&inst->remote_addr.ip_addr), new_minpoll);
+  if (inst->maxpoll < inst->minpoll)
+    NCR_ModifyMaxpoll(inst, inst->minpoll);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxpoll(NCR_Instance inst, int new_maxpoll)
+{
+  if (new_maxpoll < MIN_POLL || new_maxpoll > MAX_POLL)
+    return;
+  inst->maxpoll = new_maxpoll;
+  LOG(LOGS_INFO, "Source %s new maxpoll %d", UTI_IPToString(&inst->remote_addr.ip_addr), new_maxpoll);
+  if (inst->minpoll > inst->maxpoll)
+    NCR_ModifyMinpoll(inst, inst->maxpoll);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelay(NCR_Instance inst, double new_max_delay)
+{
+  inst->max_delay = CLAMP(0.0, new_max_delay, MAX_MAXDELAY);
+  LOG(LOGS_INFO, "Source %s new maxdelay %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelayratio(NCR_Instance inst, double new_max_delay_ratio)
+{
+  inst->max_delay_ratio = CLAMP(0.0, new_max_delay_ratio, MAX_MAXDELAYRATIO);
+  LOG(LOGS_INFO, "Source %s new maxdelayratio %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay_ratio);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMaxdelaydevratio(NCR_Instance inst, double new_max_delay_dev_ratio)
+{
+  inst->max_delay_dev_ratio = CLAMP(0.0, new_max_delay_dev_ratio, MAX_MAXDELAYDEVRATIO);
+  LOG(LOGS_INFO, "Source %s new maxdelaydevratio %f",
+      UTI_IPToString(&inst->remote_addr.ip_addr), inst->max_delay_dev_ratio);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyMinstratum(NCR_Instance inst, int new_min_stratum)
+{
+  inst->min_stratum = new_min_stratum;
+  LOG(LOGS_INFO, "Source %s new minstratum %d",
+      UTI_IPToString(&inst->remote_addr.ip_addr), new_min_stratum);
+}
+
+/* ================================================== */
+
+void
+NCR_ModifyPolltarget(NCR_Instance inst, int new_poll_target)
+{
+  inst->poll_target = MAX(1, new_poll_target);
+  LOG(LOGS_INFO, "Source %s new polltarget %d",
+      UTI_IPToString(&inst->remote_addr.ip_addr), new_poll_target);
+}
+
+/* ================================================== */
+
+void
+NCR_InitiateSampleBurst(NCR_Instance inst, int n_good_samples, int n_total_samples)
+{
+
+  if (inst->mode == MODE_CLIENT) {
+
+    /* We want to prevent burst mode being used on symmetric active
+       associations - it will play havoc with the peer's sampling
+       strategy. (This obviously relies on us having the peer
+       configured that way if he has us configured symmetric active -
+       but there's not much else we can do.) */
+
+    switch (inst->opmode) {
+      case MD_BURST_WAS_OFFLINE:
+      case MD_BURST_WAS_ONLINE:
+        /* If already burst sampling, don't start again */
+        break;
+
+      case MD_ONLINE:
+      case MD_OFFLINE:
+        inst->opmode = inst->opmode == MD_ONLINE ?
+          MD_BURST_WAS_ONLINE : MD_BURST_WAS_OFFLINE;
+        inst->burst_good_samples_to_go = n_good_samples;
+        inst->burst_total_samples_to_go = n_total_samples;
+        start_initial_timeout(inst);
+        break;
+      default:
+        assert(0);
+        break;
+    }
+  }
+
+}
+
+/* ================================================== */
+
+void
+NCR_ReportSource(NCR_Instance inst, RPT_SourceReport *report, struct timespec *now)
+{
+  report->poll = get_transmit_poll(inst);
+
+  switch (inst->mode) {
+    case MODE_CLIENT:
+      report->mode = RPT_NTP_CLIENT;
+      break;
+    case MODE_ACTIVE:
+      report->mode = RPT_NTP_PEER;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+void
+NCR_GetAuthReport(NCR_Instance inst, RPT_AuthReport *report)
+{
+  NAU_GetReport(inst->auth, report);
+}
+
+/* ================================================== */
+
+void
+NCR_GetNTPReport(NCR_Instance inst, RPT_NTPReport *report)
+{
+  *report = inst->report;
+}
+
+/* ================================================== */
+
+int
+NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+ {
+  ADF_Status status;
+
+  if (allow) {
+    if (all) {
+      status = ADF_AllowAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Allow(access_auth_table, ip_addr, subnet_bits);
+    }
+  } else {
+    if (all) {
+      status = ADF_DenyAll(access_auth_table, ip_addr, subnet_bits);
+    } else {
+      status = ADF_Deny(access_auth_table, ip_addr, subnet_bits);
+    }
+  }
+
+  if (status != ADF_SUCCESS)
+    return 0;
+
+  LOG(LOG_GetContextSeverity(LOGC_Command), "%s%s %s access from %s",
+      allow ? "Allowed" : "Denied", all ? " all" : "", "NTP",
+      UTI_IPSubnetToString(ip_addr, subnet_bits));
+
+  /* Keep server sockets open only when an address allowed */
+  if (allow) {
+    NTP_Remote_Address remote_addr;
+
+    if (server_sock_fd4 == INVALID_SOCK_FD &&
+        ADF_IsAnyAllowed(access_auth_table, IPADDR_INET4)) {
+      remote_addr.ip_addr.family = IPADDR_INET4;
+      remote_addr.port = 0;
+      server_sock_fd4 = NIO_OpenServerSocket(&remote_addr);
+    }
+    if (server_sock_fd6 == INVALID_SOCK_FD &&
+        ADF_IsAnyAllowed(access_auth_table, IPADDR_INET6)) {
+      remote_addr.ip_addr.family = IPADDR_INET6;
+      remote_addr.port = 0;
+      server_sock_fd6 = NIO_OpenServerSocket(&remote_addr);
+    }
+  } else {
+    if (server_sock_fd4 != INVALID_SOCK_FD &&
+        !ADF_IsAnyAllowed(access_auth_table, IPADDR_INET4)) {
+      NIO_CloseServerSocket(server_sock_fd4);
+      server_sock_fd4 = INVALID_SOCK_FD;
+    }
+    if (server_sock_fd6 != INVALID_SOCK_FD &&
+        !ADF_IsAnyAllowed(access_auth_table, IPADDR_INET6)) {
+      NIO_CloseServerSocket(server_sock_fd6);
+      server_sock_fd6 = INVALID_SOCK_FD;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NCR_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return ADF_IsAllowed(access_auth_table, ip_addr);
+}
+
+/* ================================================== */
+
+void
+NCR_IncrementActivityCounters(NCR_Instance inst, int *online, int *offline,
+                              int *burst_online, int *burst_offline)
+{
+  switch (inst->opmode) {
+    case MD_BURST_WAS_OFFLINE:
+      ++*burst_offline;
+      break;
+    case MD_BURST_WAS_ONLINE:
+      ++*burst_online;
+      break;
+    case MD_ONLINE:
+      ++*online;
+      break;
+    case MD_OFFLINE:
+      ++*offline;
+      break;
+    default:
+      assert(0);
+      break;
+  }
+}
+
+/* ================================================== */
+
+NTP_Remote_Address *
+NCR_GetRemoteAddress(NCR_Instance inst) 
+{
+  return &inst->remote_addr;
+}
+
+/* ================================================== */
+
+uint32_t
+NCR_GetLocalRefid(NCR_Instance inst)
+{
+  return UTI_IPToRefid(&inst->local_addr.ip_addr);
+}
+
+/* ================================================== */
+
+int NCR_IsSyncPeer(NCR_Instance inst)
+{
+  return SRC_IsSyncPeer(inst->source);
+}
+
+/* ================================================== */
+
+void
+NCR_DumpAuthData(NCR_Instance inst)
+{
+  NAU_DumpData(inst->auth);
+}
+
+/* ================================================== */
+
+static void
+broadcast_timeout(void *arg)
+{
+  BroadcastDestination *destination;
+  NTP_int64 orig_ts;
+  NTP_Local_Timestamp recv_ts;
+  int poll;
+
+  destination = ARR_GetElement(broadcasts, (long)arg);
+  poll = round(log(destination->interval) / log(2.0));
+
+  UTI_ZeroNtp64(&orig_ts);
+  zero_local_timestamp(&recv_ts);
+
+  transmit_packet(MODE_BROADCAST, 0, poll, NTP_VERSION, 0, 0, destination->auth,
+                  &orig_ts, &orig_ts, &recv_ts, NULL, NULL, NULL,
+                  &destination->addr, &destination->local_addr, NULL, NULL);
+
+  /* Requeue timeout.  We don't care if interval drifts gradually. */
+  SCH_AddTimeoutInClass(destination->interval, get_separation(poll), SAMPLING_RANDOMNESS,
+                        SCH_NtpBroadcastClass, broadcast_timeout, arg);
+}
+
+/* ================================================== */
+
+void
+NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval)
+{
+  BroadcastDestination *destination;
+
+  destination = (BroadcastDestination *)ARR_GetNewElement(broadcasts);
+
+  destination->addr = *addr;
+  destination->local_addr.ip_addr.family = IPADDR_UNSPEC;
+  destination->local_addr.if_index = INVALID_IF_INDEX;
+  destination->local_addr.sock_fd = NIO_OpenServerSocket(&destination->addr);
+  destination->auth = NAU_CreateNoneInstance();
+  destination->interval = CLAMP(1, interval, 1 << MAX_POLL);
+
+  SCH_AddTimeoutInClass(destination->interval, MAX_SAMPLING_SEPARATION, SAMPLING_RANDOMNESS,
+                        SCH_NtpBroadcastClass, broadcast_timeout,
+                        (void *)(long)(ARR_GetSize(broadcasts) - 1));
+}
diff --git a/ntp_core.h b/ntp_core.h
new file mode 100644
index 0000000..a3c5546
--- /dev/null
+++ b/ntp_core.h
@@ -0,0 +1,138 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the main NTP protocol engine
+  */
+
+#ifndef GOT_NTP_CORE_H
+#define GOT_NTP_CORE_H
+
+#include "sysincl.h"
+
+#include "addressing.h"
+#include "srcparams.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef enum {
+  NTP_SERVER, NTP_PEER
+} NTP_Source_Type;
+
+typedef struct {
+  struct timespec ts;
+  double err;
+  NTP_Timestamp_Source source;
+} NTP_Local_Timestamp;
+
+/* This is a private data type used for storing the instance record for
+   each source that we are chiming with */
+typedef struct NCR_Instance_Record *NCR_Instance;
+
+/* Init and fini functions */
+extern void NCR_Initialise(void);
+extern void NCR_Finalise(void);
+
+/* Get a new instance for a server or peer */
+extern NCR_Instance NCR_CreateInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                                       SourceParameters *params, const char *name);
+
+/* Destroy an instance */
+extern void NCR_DestroyInstance(NCR_Instance instance);
+
+/* Start an instance */
+extern void NCR_StartInstance(NCR_Instance instance);
+
+/* Reset an instance */
+extern void NCR_ResetInstance(NCR_Instance inst);
+
+/* Reset polling interval of an instance */
+extern void NCR_ResetPoll(NCR_Instance instance);
+
+/* Change the remote address of an instance */
+extern void NCR_ChangeRemoteAddress(NCR_Instance inst, NTP_Remote_Address *remote_addr,
+                                    int ntp_only);
+
+/* This routine is called when a new packet arrives off the network,
+   and it relates to a source we have an ongoing protocol exchange with */
+extern int NCR_ProcessRxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                              NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a new packet arrives off the network,
+   and we do not recognize its source */
+extern void NCR_ProcessRxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                                 NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a packet is sent to a source we have
+   an ongoing protocol exchange with */
+extern void NCR_ProcessTxKnown(NCR_Instance inst, NTP_Local_Address *local_addr,
+                               NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* This routine is called when a packet is sent to a destination we
+   do not recognize */
+extern void NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                                 NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* Slew receive and transmit times in instance records */
+extern void NCR_SlewTimes(NCR_Instance inst, struct timespec *when, double dfreq, double doffset);
+
+/* Take a particular source online (i.e. start sampling it) or offline
+   (i.e. stop sampling it) */
+extern void NCR_SetConnectivity(NCR_Instance inst, SRC_Connectivity connectivity);
+
+extern void NCR_ModifyMinpoll(NCR_Instance inst, int new_minpoll);
+
+extern void NCR_ModifyMaxpoll(NCR_Instance inst, int new_maxpoll);
+
+extern void NCR_ModifyMaxdelay(NCR_Instance inst, double new_max_delay);
+
+extern void NCR_ModifyMaxdelayratio(NCR_Instance inst, double new_max_delay_ratio);
+
+extern void NCR_ModifyMaxdelaydevratio(NCR_Instance inst, double new_max_delay_dev_ratio);
+
+extern void NCR_ModifyMinstratum(NCR_Instance inst, int new_min_stratum);
+
+extern void NCR_ModifyPolltarget(NCR_Instance inst, int new_poll_target);
+
+extern void NCR_InitiateSampleBurst(NCR_Instance inst, int n_good_samples, int n_total_samples);
+
+extern void NCR_ReportSource(NCR_Instance inst, RPT_SourceReport *report, struct timespec *now);
+extern void NCR_GetAuthReport(NCR_Instance inst, RPT_AuthReport *report);
+extern void NCR_GetNTPReport(NCR_Instance inst, RPT_NTPReport *report);
+
+extern int NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all);
+extern int NCR_CheckAccessRestriction(IPAddr *ip_addr);
+
+extern void NCR_IncrementActivityCounters(NCR_Instance inst, int *online, int *offline, 
+                                          int *burst_online, int *burst_offline);
+
+extern NTP_Remote_Address *NCR_GetRemoteAddress(NCR_Instance instance);
+
+extern uint32_t NCR_GetLocalRefid(NCR_Instance inst);
+
+extern int NCR_IsSyncPeer(NCR_Instance instance);
+
+extern void NCR_DumpAuthData(NCR_Instance inst);
+
+extern void NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval);
+
+#endif /* GOT_NTP_CORE_H */
diff --git a/ntp_ext.c b/ntp_ext.c
new file mode 100644
index 0000000..d2babb1
--- /dev/null
+++ b/ntp_ext.c
@@ -0,0 +1,192 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions for adding and parsing NTPv4 extension fields
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "ntp_ext.h"
+
+struct ExtFieldHeader {
+  uint16_t type;
+  uint16_t length;
+};
+
+/* ================================================== */
+
+static int
+format_field(unsigned char *buffer, int buffer_length, int start,
+             int type, int body_length, int *length, void **body)
+{
+  struct ExtFieldHeader *header;
+
+  if (buffer_length < 0 || start < 0 || buffer_length <= start ||
+      buffer_length - start < sizeof (*header) || start % 4 != 0)
+    return 0;
+
+  header = (struct ExtFieldHeader *)(buffer + start);
+
+  if (body_length < 0 || sizeof (*header) + body_length > 0xffff ||
+      start + sizeof (*header) + body_length > buffer_length || body_length % 4 != 0)
+    return 0;
+
+  header->type = htons(type);
+  header->length = htons(sizeof (*header) + body_length);
+  *length = sizeof (*header) + body_length;
+  *body = header + 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_SetField(unsigned char *buffer, int buffer_length, int start,
+             int type, void *body, int body_length, int *length)
+{
+  void *ef_body;
+
+  if (!format_field(buffer, buffer_length, start, type, body_length, length, &ef_body))
+    return 0;
+
+  memcpy(ef_body, body, body_length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_AddBlankField(NTP_Packet *packet, NTP_PacketInfo *info, int type, int body_length, void **body)
+{
+  int ef_length, length = info->length;
+
+  if (length < NTP_HEADER_LENGTH || length >= sizeof (*packet) || length % 4 != 0)
+    return 0;
+
+  /* Only NTPv4 packets can have extension fields */
+  if (info->version != 4)
+    return 0;
+
+  if (!format_field((unsigned char *)packet, sizeof (*packet), length,
+                    type, body_length, &ef_length, body))
+    return 0;
+
+  if (ef_length < NTP_MIN_EF_LENGTH)
+    return 0;
+
+  info->length += ef_length;
+  info->ext_fields++;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_AddField(NTP_Packet *packet, NTP_PacketInfo *info,
+             int type, void *body, int body_length)
+{
+  void *ef_body;
+
+  if (!NEF_AddBlankField(packet, info, type, body_length, &ef_body))
+    return 0;
+
+  memcpy(ef_body, body, body_length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_ParseSingleField(unsigned char *buffer, int buffer_length, int start,
+                     int *length, int *type, void **body, int *body_length)
+{
+  struct ExtFieldHeader *header;
+  int ef_length;
+
+  if (buffer_length < 0 || start < 0 || buffer_length <= start ||
+      buffer_length - start < sizeof (*header))
+    return 0;
+
+  header = (struct ExtFieldHeader *)(buffer + start);
+
+  assert(sizeof (*header) == 4);
+
+  ef_length = ntohs(header->length);
+
+  if (ef_length < (int)(sizeof (*header)) || start + ef_length > buffer_length ||
+      ef_length % 4 != 0)
+    return 0;
+
+  if (length)
+    *length = ef_length;
+  if (type)
+    *type = ntohs(header->type);
+  if (body)
+    *body = header + 1;
+  if (body_length)
+    *body_length = ef_length - sizeof (*header);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NEF_ParseField(NTP_Packet *packet, int packet_length, int start,
+               int *length, int *type, void **body, int *body_length)
+{
+  int ef_length;
+
+  if (packet_length <= NTP_HEADER_LENGTH || packet_length > sizeof (*packet) ||
+      packet_length <= start || packet_length % 4 != 0 ||
+      start < NTP_HEADER_LENGTH || start % 4 != 0)
+    return 0;
+
+  /* Only NTPv4 packets have extension fields */
+  if (NTP_LVM_TO_VERSION(packet->lvm) != 4)
+    return 0;
+
+  /* Check if the remaining data is a MAC.  RFC 7822 specifies the maximum
+     length of a MAC in NTPv4 packets in order to enable deterministic
+     parsing. */
+  if (packet_length - start <= NTP_MAX_V4_MAC_LENGTH)
+    return 0;
+
+  if (!NEF_ParseSingleField((unsigned char *)packet, packet_length, start,
+                            &ef_length, type, body, body_length))
+    return 0;
+
+  if (ef_length < NTP_MIN_EF_LENGTH)
+    return 0;
+
+  if (length)
+    *length = ef_length;
+
+  return 1;
+}
diff --git a/ntp_ext.h b/ntp_ext.h
new file mode 100644
index 0000000..7405be8
--- /dev/null
+++ b/ntp_ext.h
@@ -0,0 +1,43 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NTP extension fields
+  */
+
+#ifndef GOT_NTP_EXT_H
+#define GOT_NTP_EXT_H
+
+#include "ntp.h"
+
+extern int NEF_SetField(unsigned char *buffer, int buffer_length, int start,
+                        int type, void *body, int body_length, int *length);
+extern int NEF_AddBlankField(NTP_Packet *packet, NTP_PacketInfo *info, int type,
+                             int body_length, void **body);
+extern int NEF_AddField(NTP_Packet *packet, NTP_PacketInfo *info,
+                        int type, void *body, int body_length);
+extern int NEF_ParseSingleField(unsigned char *buffer, int buffer_length, int start,
+                                int *length, int *type, void **body, int *body_length);
+extern int NEF_ParseField(NTP_Packet *packet, int packet_length, int start,
+                          int *length, int *type, void **body, int *body_length);
+
+#endif
diff --git a/ntp_io.c b/ntp_io.c
new file mode 100644
index 0000000..fce7b17
--- /dev/null
+++ b/ntp_io.c
@@ -0,0 +1,623 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Timo Teras  2009
+ * Copyright (C) Miroslav Lichvar  2009, 2013-2016, 2018-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file deals with the IO aspects of reading and writing NTP packets
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "memory.h"
+#include "ntp_io.h"
+#include "ntp_core.h"
+#include "ntp_sources.h"
+#include "ptp.h"
+#include "sched.h"
+#include "socket.h"
+#include "local.h"
+#include "logging.h"
+#include "conf.h"
+#include "privops.h"
+#include "util.h"
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include "ntp_io_linux.h"
+#endif
+
+#define INVALID_SOCK_FD -1
+
+/* The server/peer and client sockets for IPv4 and IPv6 */
+static int server_sock_fd4;
+static int server_sock_fd6;
+static int client_sock_fd4;
+static int client_sock_fd6;
+
+/* Reference counters for server sockets to keep them open only when needed */
+static int server_sock_ref4;
+static int server_sock_ref6;
+
+/* Flag indicating we create a new connected client socket for each
+   server instead of sharing client_sock_fd4 and client_sock_fd6 */
+static int separate_client_sockets;
+
+/* Flag indicating the server sockets are not created dynamically when needed,
+   either to have a socket for client requests when separate client sockets
+   are disabled and client port is equal to server port, or the server port is
+   disabled */
+static int permanent_server_sockets;
+
+/* Flag indicating the server IPv4 socket is bound to an address */
+static int bound_server_sock_fd4;
+
+/* PTP event port, or 0 if disabled */
+static int ptp_port;
+
+/* Shared server/client sockets for NTP-over-PTP */
+static int ptp_sock_fd4;
+static int ptp_sock_fd6;
+
+/* Buffer for transmitted NTP-over-PTP messages */
+static PTP_NtpMessage *ptp_message;
+
+/* Flag indicating that we have been initialised */
+static int initialised=0;
+
+/* ================================================== */
+
+/* Forward prototypes */
+static void read_from_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static int
+open_socket(int family, int local_port, int client_only, IPSockAddr *remote_addr)
+{
+  int sock_fd, sock_flags, dscp, events = SCH_FILE_INPUT;
+  IPSockAddr local_addr;
+  char *iface;
+
+  if (!SCK_IsIpFamilyEnabled(family))
+    return INVALID_SOCK_FD;
+
+  if (!client_only) {
+    CNF_GetBindAddress(family, &local_addr.ip_addr);
+    iface = CNF_GetBindNtpInterface();
+  } else {
+    CNF_GetBindAcquisitionAddress(family, &local_addr.ip_addr);
+    iface = CNF_GetBindAcquisitionInterface();
+  }
+
+  local_addr.port = local_port;
+
+  sock_flags = SCK_FLAG_RX_DEST_ADDR | SCK_FLAG_PRIV_BIND;
+  if (!client_only)
+    sock_flags |= SCK_FLAG_BROADCAST;
+
+  sock_fd = SCK_OpenUdpSocket(remote_addr, &local_addr, iface, sock_flags);
+  if (sock_fd < 0) {
+    if (!client_only)
+      LOG(LOGS_ERR, "Could not open NTP socket on %s", UTI_IPSockAddrToString(&local_addr));
+    return INVALID_SOCK_FD;
+  }
+
+  dscp = CNF_GetNtpDscp();
+  if (dscp > 0 && dscp < 64) {
+#ifdef IP_TOS
+    if (family == IPADDR_INET4)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_TOS, dscp << 2))
+        ;
+#endif
+#if defined(FEAT_IPV6) && defined(IPV6_TCLASS)
+    if (family == IPADDR_INET6)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_TCLASS, dscp << 2))
+        ;
+#endif
+  }
+
+  if (!client_only && family == IPADDR_INET4 && local_addr.port > 0)
+    bound_server_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;
+
+  /* Enable kernel/HW timestamping of packets */
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (!NIO_Linux_SetTimestampSocketOptions(sock_fd, client_only, &events))
+#endif
+    if (!SCK_EnableKernelRxTimestamping(sock_fd))
+      ;
+
+  /* Register handler for read and possibly exception events on the socket */
+  SCH_AddFileHandler(sock_fd, events, read_from_socket, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+open_separate_client_socket(IPSockAddr *remote_addr)
+{
+  return open_socket(remote_addr->ip_addr.family, 0, 1, remote_addr);
+}
+
+/* ================================================== */
+
+static void
+close_socket(int sock_fd)
+{
+  if (sock_fd == INVALID_SOCK_FD)
+    return;
+
+  SCH_RemoveFileHandler(sock_fd);
+  SCK_CloseSocket(sock_fd);
+}
+
+/* ================================================== */
+
+void
+NIO_Initialise(void)
+{
+  int server_port, client_port;
+
+  assert(!initialised);
+  initialised = 1;
+
+#ifdef PRIVOPS_BINDSOCKET
+  SCK_SetPrivBind(PRV_BindSocket);
+#endif
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  NIO_Linux_Initialise();
+#else
+  if (1) {
+    CNF_HwTsInterface *conf_iface;
+    if (CNF_GetHwTsInterface(0, &conf_iface))
+      LOG_FATAL("HW timestamping not supported");
+  }
+#endif
+
+  server_port = CNF_GetNTPPort();
+  client_port = CNF_GetAcquisitionPort();
+
+  /* Use separate connected sockets if client port is negative */
+  separate_client_sockets = client_port < 0;
+  if (client_port < 0)
+    client_port = 0;
+
+  permanent_server_sockets = !server_port || (!separate_client_sockets &&
+                                              client_port == server_port);
+
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+  client_sock_fd4 = INVALID_SOCK_FD;
+  client_sock_fd6 = INVALID_SOCK_FD;
+  server_sock_ref4 = 0;
+  server_sock_ref6 = 0;
+
+  if (permanent_server_sockets && server_port) {
+    server_sock_fd4 = open_socket(IPADDR_INET4, server_port, 0, NULL);
+    server_sock_fd6 = open_socket(IPADDR_INET6, server_port, 0, NULL);
+  }
+
+  if (!separate_client_sockets) {
+    if (client_port != server_port || !server_port) {
+      client_sock_fd4 = open_socket(IPADDR_INET4, client_port, 1, NULL);
+      client_sock_fd6 = open_socket(IPADDR_INET6, client_port, 1, NULL);
+    } else {
+      client_sock_fd4 = server_sock_fd4;
+      client_sock_fd6 = server_sock_fd6;
+    }
+  }
+
+  if ((server_port && permanent_server_sockets &&
+       server_sock_fd4 == INVALID_SOCK_FD && server_sock_fd6 == INVALID_SOCK_FD) ||
+      (!separate_client_sockets &&
+       client_sock_fd4 == INVALID_SOCK_FD && client_sock_fd6 == INVALID_SOCK_FD)) {
+    LOG_FATAL("Could not open NTP sockets");
+  }
+
+  ptp_port = CNF_GetPtpPort();
+  ptp_sock_fd4 = INVALID_SOCK_FD;
+  ptp_sock_fd6 = INVALID_SOCK_FD;
+  ptp_message = NULL;
+
+  if (ptp_port > 0) {
+    ptp_sock_fd4 = open_socket(IPADDR_INET4, ptp_port, 0, NULL);
+    ptp_sock_fd6 = open_socket(IPADDR_INET6, ptp_port, 0, NULL);
+    ptp_message = MallocNew(PTP_NtpMessage);
+  }
+}
+
+/* ================================================== */
+
+void
+NIO_Finalise(void)
+{
+  if (server_sock_fd4 != client_sock_fd4)
+    close_socket(client_sock_fd4);
+  close_socket(server_sock_fd4);
+  server_sock_fd4 = client_sock_fd4 = INVALID_SOCK_FD;
+
+  if (server_sock_fd6 != client_sock_fd6)
+    close_socket(client_sock_fd6);
+  close_socket(server_sock_fd6);
+  server_sock_fd6 = client_sock_fd6 = INVALID_SOCK_FD;
+
+  close_socket(ptp_sock_fd4);
+  close_socket(ptp_sock_fd6);
+  ptp_sock_fd4 = ptp_sock_fd6 = INVALID_SOCK_FD;
+  Free(ptp_message);
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  NIO_Linux_Finalise();
+#endif
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+int
+NIO_IsHwTsEnabled(void)
+{
+#ifdef HAVE_LINUX_TIMESTAMPING
+  return NIO_Linux_IsHwTsEnabled();
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+int
+NIO_OpenClientSocket(NTP_Remote_Address *remote_addr)
+{
+  switch (remote_addr->ip_addr.family) {
+    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd4;
+    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd6;
+    default:
+      return INVALID_SOCK_FD;
+  }
+}
+
+/* ================================================== */
+
+int
+NIO_OpenServerSocket(NTP_Remote_Address *remote_addr)
+{
+  switch (remote_addr->ip_addr.family) {
+    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
+      if (permanent_server_sockets)
+        return server_sock_fd4;
+      if (server_sock_fd4 == INVALID_SOCK_FD)
+        server_sock_fd4 = open_socket(IPADDR_INET4, CNF_GetNTPPort(), 0, NULL);
+      if (server_sock_fd4 != INVALID_SOCK_FD)
+        server_sock_ref4++;
+      return server_sock_fd4;
+    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
+      if (permanent_server_sockets)
+        return server_sock_fd6;
+      if (server_sock_fd6 == INVALID_SOCK_FD)
+        server_sock_fd6 = open_socket(IPADDR_INET6, CNF_GetNTPPort(), 0, NULL);
+      if (server_sock_fd6 != INVALID_SOCK_FD)
+        server_sock_ref6++;
+      return server_sock_fd6;
+    default:
+      return INVALID_SOCK_FD;
+  }
+}
+
+/* ================================================== */
+
+static int
+is_ptp_socket(int sock_fd)
+{
+  return ptp_port > 0 && sock_fd != INVALID_SOCK_FD &&
+    (sock_fd == ptp_sock_fd4 || sock_fd == ptp_sock_fd6);
+}
+
+/* ================================================== */
+
+void
+NIO_CloseClientSocket(int sock_fd)
+{
+  if (is_ptp_socket(sock_fd))
+    return;
+
+  if (separate_client_sockets)
+    close_socket(sock_fd);
+}
+
+/* ================================================== */
+
+void
+NIO_CloseServerSocket(int sock_fd)
+{
+  if (permanent_server_sockets || sock_fd == INVALID_SOCK_FD || is_ptp_socket(sock_fd))
+    return;
+
+  if (sock_fd == server_sock_fd4) {
+    if (--server_sock_ref4 <= 0) {
+      close_socket(server_sock_fd4);
+      server_sock_fd4 = INVALID_SOCK_FD;
+    }
+  } else if (sock_fd == server_sock_fd6) {
+    if (--server_sock_ref6 <= 0) {
+      close_socket(server_sock_fd6);
+      server_sock_fd6 = INVALID_SOCK_FD;
+    }
+  } else {
+    assert(0);
+  }
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerSocket(int sock_fd)
+{
+  return sock_fd != INVALID_SOCK_FD &&
+    (sock_fd == server_sock_fd4 || sock_fd == server_sock_fd6 || is_ptp_socket(sock_fd));
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerSocketOpen(void)
+{
+  return server_sock_fd4 != INVALID_SOCK_FD || server_sock_fd6 != INVALID_SOCK_FD ||
+    ptp_sock_fd4 != INVALID_SOCK_FD || ptp_sock_fd6 != INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+int
+NIO_IsServerConnectable(NTP_Remote_Address *remote_addr)
+{
+  int sock_fd;
+
+  sock_fd = open_separate_client_socket(remote_addr);
+  if (sock_fd == INVALID_SOCK_FD)
+    return 0;
+
+  close_socket(sock_fd);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_message(SCK_Message *message, int sock_fd, int event)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  struct timespec sched_ts;
+
+  SCH_GetLastEventTime(&local_ts.ts, &local_ts.err, NULL);
+  local_ts.source = NTP_TS_DAEMON;
+  sched_ts = local_ts.ts;
+
+  if (message->addr_type != SCK_ADDR_IP) {
+    DEBUG_LOG("Unexpected address type");
+    return;
+  }
+
+  local_addr.ip_addr = message->local_addr.ip;
+  local_addr.if_index = message->if_index;;
+  local_addr.sock_fd = sock_fd;
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (NIO_Linux_ProcessMessage(message, &local_addr, &local_ts, event))
+    return;
+#else
+  if (!UTI_IsZeroTimespec(&message->timestamp.kernel)) {
+    LCL_CookTime(&message->timestamp.kernel, &local_ts.ts, &local_ts.err);
+    local_ts.source = NTP_TS_KERNEL;
+  }
+#endif
+
+  if (local_ts.source != NTP_TS_DAEMON)
+    DEBUG_LOG("Updated RX timestamp delay=%.9f tss=%u",
+              UTI_DiffTimespecsToDouble(&sched_ts, &local_ts.ts), local_ts.source);
+
+  if (!NIO_UnwrapMessage(message, sock_fd))
+    return;
+
+  /* Just ignore the packet if it's not of a recognized length */
+  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet)) {
+    DEBUG_LOG("Unexpected length");
+    return;
+  }
+
+  NSR_ProcessRx(&message->remote_addr.ip, &local_addr, &local_ts, message->data, message->length);
+}
+
+/* ================================================== */
+
+static void
+read_from_socket(int sock_fd, int event, void *anything)
+{
+  SCK_Message *messages;
+  int i, received, flags = 0;
+
+  if (event == SCH_FILE_EXCEPTION) {
+#ifdef HAVE_LINUX_TIMESTAMPING
+    flags |= SCK_FLAG_MSG_ERRQUEUE;
+#else
+    assert(0);
+#endif
+  }
+
+  messages = SCK_ReceiveMessages(sock_fd, flags, &received);
+  if (!messages)
+    return;
+
+  for (i = 0; i < received; i++)
+    process_message(&messages[i], sock_fd, event);
+}
+
+/* ================================================== */
+
+int
+NIO_UnwrapMessage(SCK_Message *message, int sock_fd)
+{
+  PTP_NtpMessage *msg;
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (message->length <= PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  msg = message->data;
+
+  if (msg->header.type != PTP_TYPE_DELAY_REQ || msg->header.version != PTP_VERSION ||
+      ntohs(msg->header.length) != message->length ||
+      msg->header.domain != PTP_DOMAIN_NTP ||
+      ntohs(msg->header.flags) != PTP_FLAG_UNICAST ||
+      ntohs(msg->tlv_header.type) != PTP_TLV_NTP ||
+      ntohs(msg->tlv_header.length) != message->length - PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected PTP message");
+    return 0;
+  }
+
+  message->data = (char *)message->data + PTP_NTP_PREFIX_LENGTH;
+  message->length -= PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Unwrapped PTP->NTP len=%d", message->length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+wrap_message(SCK_Message *message, int sock_fd)
+{
+  static uint16_t sequence_id = 0;
+
+  assert(PTP_NTP_PREFIX_LENGTH == 48);
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (!ptp_message)
+    return 0;
+
+  if (message->length < NTP_HEADER_LENGTH ||
+      message->length + PTP_NTP_PREFIX_LENGTH > sizeof (*ptp_message)) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  memset(ptp_message, 0, PTP_NTP_PREFIX_LENGTH);
+  ptp_message->header.type = PTP_TYPE_DELAY_REQ;
+  ptp_message->header.version = PTP_VERSION;
+  ptp_message->header.length = htons(PTP_NTP_PREFIX_LENGTH + message->length);
+  ptp_message->header.domain = PTP_DOMAIN_NTP;
+  ptp_message->header.flags = htons(PTP_FLAG_UNICAST);
+  ptp_message->header.sequence_id = htons(sequence_id++);
+  ptp_message->tlv_header.type = htons(PTP_TLV_NTP);
+  ptp_message->tlv_header.length = htons(message->length);
+  memcpy((char *)ptp_message + PTP_NTP_PREFIX_LENGTH, message->data, message->length);
+
+  message->data = ptp_message;
+  message->length += PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Wrapped NTP->PTP len=%d", message->length - PTP_NTP_PREFIX_LENGTH);
+
+  return 1;
+}
+
+/* ================================================== */
+/* Send a packet to remote address from local address */
+
+int
+NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
+               NTP_Local_Address *local_addr, int length, int process_tx)
+{
+  SCK_Message message;
+
+  assert(initialised);
+
+  if (local_addr->sock_fd == INVALID_SOCK_FD) {
+    DEBUG_LOG("No socket to send to %s", UTI_IPSockAddrToString(remote_addr));
+    return 0;
+  }
+
+  SCK_InitMessage(&message, SCK_ADDR_IP);
+
+  message.data = packet;
+  message.length = length;
+
+  if (!wrap_message(&message, local_addr->sock_fd))
+    return 0;
+
+  /* Specify remote address if the socket is not connected */
+  if (NIO_IsServerSocket(local_addr->sock_fd) || !separate_client_sockets) {
+    message.remote_addr.ip.ip_addr = remote_addr->ip_addr;
+    message.remote_addr.ip.port = remote_addr->port;
+  }
+
+  message.local_addr.ip = local_addr->ip_addr;
+
+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  message.if_index = SCK_IsLinkLocalIPAddress(&message.remote_addr.ip.ip_addr) ?
+                       local_addr->if_index : INVALID_IF_INDEX;
+
+#if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
+  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
+  if (message.local_addr.ip.family == IPADDR_INET4 &&
+      (bound_server_sock_fd4 || !NIO_IsServerSocket(local_addr->sock_fd)))
+    message.local_addr.ip.family = IPADDR_UNSPEC;
+#endif
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (process_tx)
+    NIO_Linux_RequestTxTimestamp(&message, local_addr->sock_fd);
+#endif
+
+  if (!SCK_SendMessage(local_addr->sock_fd, &message, 0))
+    return 0;
+
+  return 1;
+}
diff --git a/ntp_io.h b/ntp_io.h
new file mode 100644
index 0000000..427bd96
--- /dev/null
+++ b/ntp_io.h
@@ -0,0 +1,73 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the NTP socket I/O bits.
+
+  */
+
+#ifndef GOT_NTP_IO_H
+#define GOT_NTP_IO_H
+
+#include "ntp.h"
+#include "addressing.h"
+#include "socket.h"
+
+/* Function to initialise the module. */
+extern void NIO_Initialise(void);
+
+/* Function to finalise the module */
+extern void NIO_Finalise(void);
+
+/* Function to check if HW timestamping is enabled on any interface */
+extern int NIO_IsHwTsEnabled(void);
+
+/* Function to obtain a socket for sending client packets */
+extern int NIO_OpenClientSocket(NTP_Remote_Address *remote_addr);
+
+/* Function to obtain a socket for sending server/peer packets */
+extern int NIO_OpenServerSocket(NTP_Remote_Address *remote_addr);
+
+/* Function to close a socket returned by NIO_OpenClientSocket() */
+extern void NIO_CloseClientSocket(int sock_fd);
+
+/* Function to close a socket returned by NIO_OpenServerSocket() */
+extern void NIO_CloseServerSocket(int sock_fd);
+
+/* Function to check if socket is a server socket */
+extern int NIO_IsServerSocket(int sock_fd);
+
+/* Function to check if a server socket is currently open */
+extern int NIO_IsServerSocketOpen(void);
+
+/* Function to check if client packets can be sent to a server */
+extern int NIO_IsServerConnectable(NTP_Remote_Address *remote_addr);
+
+/* Function to unwrap an NTP message from non-native transport (e.g. PTP) */
+extern int NIO_UnwrapMessage(SCK_Message *message, int sock_fd);
+
+/* Function to transmit a packet */
+extern int NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
+                          NTP_Local_Address *local_addr, int length, int process_tx);
+
+#endif /* GOT_NTP_IO_H */
diff --git a/ntp_io_linux.c b/ntp_io_linux.c
new file mode 100644
index 0000000..8f93f59
--- /dev/null
+++ b/ntp_io_linux.c
@@ -0,0 +1,810 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2019, 2021-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions for NTP I/O specific to Linux
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <ifaddrs.h>
+#include <linux/ethtool.h>
+#include <linux/net_tstamp.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+
+#include "array.h"
+#include "conf.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "ntp_io_linux.h"
+#include "ntp_sources.h"
+#include "sched.h"
+#include "socket.h"
+#include "sys_linux.h"
+#include "util.h"
+
+struct Interface {
+  char name[IF_NAMESIZE];
+  int if_index;
+  int phc_fd;
+  int phc_mode;
+  int phc_nocrossts;
+  /* Link speed in mbit/s */
+  int link_speed;
+  /* Start of UDP data at layer 2 for IPv4 and IPv6 */
+  int l2_udp4_ntp_start;
+  int l2_udp6_ntp_start;
+  /* Compensation of errors in TX and RX timestamping */
+  double tx_comp;
+  double rx_comp;
+  HCL_Instance clock;
+  int maxpoll;
+  SCH_TimeoutID poll_timeout_id;
+};
+
+/* Number of PHC readings per HW clock sample */
+#define PHC_READINGS 25
+
+/* Minimum and maximum interval between PHC readings */
+#define MIN_PHC_POLL -6
+#define MAX_PHC_POLL 20
+
+/* Maximum acceptable offset between SW/HW and daemon timestamp */
+#define MAX_TS_DELAY 1.0
+
+/* Array of Interfaces */
+static ARR_Instance interfaces;
+
+/* RX/TX and TX-specific timestamping socket options */
+static int ts_flags;
+static int ts_tx_flags;
+
+/* Flag indicating the socket options can't be changed in control messages */
+static int permanent_ts_options;
+
+/* Unbound socket keeping the kernel RX timestamping permanently enabled
+   in order to avoid a race condition between receiving a server response
+   and the kernel actually starting to timestamp received packets after
+   enabling the timestamping and sending a request */
+static int dummy_rxts_socket;
+
+#define INVALID_SOCK_FD -3
+
+/* ================================================== */
+
+static void poll_phc(struct Interface *iface, struct timespec *now);
+
+/* ================================================== */
+
+static int
+add_interface(CNF_HwTsInterface *conf_iface)
+{
+  int sock_fd, if_index, minpoll, phc_fd, req_hwts_flags, rx_filter;
+  struct ethtool_ts_info ts_info;
+  struct hwtstamp_config ts_config;
+  struct ifreq req;
+  unsigned int i;
+  struct Interface *iface;
+
+  /* Check if the interface was not already added */
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    if (!strcmp(conf_iface->name, ((struct Interface *)ARR_GetElement(interfaces, i))->name))
+      return 1;
+  }
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  memset(&req, 0, sizeof (req));
+  memset(&ts_info, 0, sizeof (ts_info));
+
+  if (snprintf(req.ifr_name, sizeof (req.ifr_name), "%s", conf_iface->name) >=
+      sizeof (req.ifr_name)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if (ioctl(sock_fd, SIOCGIFINDEX, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCGIFINDEX", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if_index = req.ifr_ifindex;
+
+  ts_info.cmd = ETHTOOL_GET_TS_INFO;
+  req.ifr_data = (char *)&ts_info;
+
+  if (ioctl(sock_fd, SIOCETHTOOL, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCETHTOOL", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  req_hwts_flags = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_TX_HARDWARE |
+                   SOF_TIMESTAMPING_RAW_HARDWARE;
+  if ((ts_info.so_timestamping & req_hwts_flags) != req_hwts_flags) {
+    DEBUG_LOG("HW timestamping not supported on %s", req.ifr_name);
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  if (ts_info.phc_index < 0) {
+    DEBUG_LOG("PHC missing on %s", req.ifr_name);
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  switch (conf_iface->rxfilter) {
+    case CNF_HWTS_RXFILTER_ANY:
+#ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_NTP_ALL))
+        rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+      else
+#endif
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))
+        rx_filter = HWTSTAMP_FILTER_ALL;
+      else
+        rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+    case CNF_HWTS_RXFILTER_NONE:
+      rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+#ifdef HAVE_LINUX_TIMESTAMPING_RXFILTER_NTP
+    case CNF_HWTS_RXFILTER_NTP:
+      rx_filter = HWTSTAMP_FILTER_NTP_ALL;
+      break;
+#endif
+    case CNF_HWTS_RXFILTER_PTP:
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_L4_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_L4_EVENT;
+      else if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_EVENT;
+      else
+        rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
+    default:
+      rx_filter = HWTSTAMP_FILTER_ALL;
+      break;
+  }
+
+  ts_config.flags = 0;
+  ts_config.tx_type = HWTSTAMP_TX_ON;
+  ts_config.rx_filter = rx_filter;
+  req.ifr_data = (char *)&ts_config;
+
+  if (ioctl(sock_fd, SIOCSHWTSTAMP, &req)) {
+    LOG(errno == EPERM ? LOGS_ERR : LOGS_DEBUG,
+        "ioctl(%s) failed : %s", "SIOCSHWTSTAMP", strerror(errno));
+
+    /* Check the current timestamping configuration in case this interface
+       allows only reading of the configuration and it was already configured
+       as requested */
+    req.ifr_data = (char *)&ts_config;
+#ifdef SIOCGHWTSTAMP
+    if (ioctl(sock_fd, SIOCGHWTSTAMP, &req) ||
+        ts_config.tx_type != HWTSTAMP_TX_ON || ts_config.rx_filter != rx_filter)
+#endif
+    {
+      SCK_CloseSocket(sock_fd);
+      return 0;
+    }
+  }
+
+  SCK_CloseSocket(sock_fd);
+
+  phc_fd = SYS_Linux_OpenPHC(NULL, ts_info.phc_index);
+  if (phc_fd < 0)
+    return 0;
+
+  iface = ARR_GetNewElement(interfaces);
+
+  snprintf(iface->name, sizeof (iface->name), "%s", conf_iface->name);
+  iface->if_index = if_index;
+  iface->phc_fd = phc_fd;
+  iface->phc_mode = 0;
+  iface->phc_nocrossts = conf_iface->nocrossts;
+
+  /* Start with 1 gbit and no VLANs or IPv4/IPv6 options */
+  iface->link_speed = 1000;
+  iface->l2_udp4_ntp_start = 42;
+  iface->l2_udp6_ntp_start = 62;
+
+  iface->tx_comp = conf_iface->tx_comp;
+  iface->rx_comp = conf_iface->rx_comp;
+
+  minpoll = CLAMP(MIN_PHC_POLL, conf_iface->minpoll, MAX_PHC_POLL);
+  iface->clock = HCL_CreateInstance(conf_iface->min_samples, conf_iface->max_samples,
+                                    UTI_Log2ToDouble(minpoll), conf_iface->precision);
+
+  iface->maxpoll = CLAMP(minpoll, conf_iface->maxpoll, MAX_PHC_POLL);
+
+  /* Do not schedule the first poll timeout here!  The argument (interface) can
+     move until all interfaces are added.  Wait for the first HW timestamp. */
+  iface->poll_timeout_id = 0;
+
+  LOG(LOGS_INFO, "Enabled HW timestamping %son %s",
+      ts_config.rx_filter == HWTSTAMP_FILTER_NONE ? "(TX only) " : "", iface->name);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+add_all_interfaces(CNF_HwTsInterface *conf_iface_all)
+{
+  CNF_HwTsInterface conf_iface;
+  struct ifaddrs *ifaddr, *ifa;
+  int r;
+
+  conf_iface = *conf_iface_all;
+
+  if (getifaddrs(&ifaddr)) {
+    DEBUG_LOG("getifaddrs() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  for (r = 0, ifa = ifaddr; ifa; ifa = ifa->ifa_next) {
+    conf_iface.name = ifa->ifa_name;
+    if (add_interface(&conf_iface))
+      r = 1;
+  }
+  
+  freeifaddrs(ifaddr);
+
+  /* Return success if at least one interface was added */
+  return r;
+}
+
+/* ================================================== */
+
+static void
+update_interface_speed(struct Interface *iface)
+{
+  struct ethtool_cmd cmd;
+  struct ifreq req;
+  int sock_fd, link_speed;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return;
+
+  memset(&req, 0, sizeof (req));
+  memset(&cmd, 0, sizeof (cmd));
+
+  snprintf(req.ifr_name, sizeof (req.ifr_name), "%s", iface->name);
+  cmd.cmd = ETHTOOL_GSET;
+  req.ifr_data = (char *)&cmd;
+
+  if (ioctl(sock_fd, SIOCETHTOOL, &req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCETHTOOL", strerror(errno));
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  SCK_CloseSocket(sock_fd);
+
+  link_speed = ethtool_cmd_speed(&cmd);
+
+  if (iface->link_speed != link_speed) {
+    iface->link_speed = link_speed;
+    DEBUG_LOG("Updated speed of %s to %d Mb/s", iface->name, link_speed);
+  }
+}
+
+/* ================================================== */
+
+#if defined(HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO) || defined(HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW)
+static int
+check_timestamping_option(int option)
+{
+  int sock_fd;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPING, option)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  SCK_CloseSocket(sock_fd);
+  return 1;
+}
+#endif
+
+/* ================================================== */
+
+static int
+open_dummy_socket(void)
+{
+  int sock_fd, events = 0;
+
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!NIO_Linux_SetTimestampSocketOptions(sock_fd, 1, &events)) {
+    SCK_CloseSocket(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_Initialise(void)
+{
+  CNF_HwTsInterface *conf_iface;
+  unsigned int i;
+  int hwts;
+
+  interfaces = ARR_CreateInstance(sizeof (struct Interface));
+
+  /* Enable HW timestamping on specified interfaces.  If "*" was specified, try
+     all interfaces.  If no interface was specified, enable SW timestamping. */
+
+  for (i = hwts = 0; CNF_GetHwTsInterface(i, &conf_iface); i++) {
+    if (!strcmp("*", conf_iface->name))
+      continue;
+    if (!add_interface(conf_iface))
+      LOG_FATAL("Could not enable HW timestamping on %s", conf_iface->name);
+    hwts = 1;
+  }
+
+  for (i = 0; CNF_GetHwTsInterface(i, &conf_iface); i++) {
+    if (strcmp("*", conf_iface->name))
+      continue;
+    if (add_all_interfaces(conf_iface))
+      hwts = 1;
+    break;
+  }
+
+  ts_flags = SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_RX_SOFTWARE;
+  ts_tx_flags = SOF_TIMESTAMPING_TX_SOFTWARE;
+
+  if (hwts) {
+    ts_flags |= SOF_TIMESTAMPING_RAW_HARDWARE | SOF_TIMESTAMPING_RX_HARDWARE;
+    ts_tx_flags |= SOF_TIMESTAMPING_TX_HARDWARE;
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO
+    if (check_timestamping_option(SOF_TIMESTAMPING_OPT_PKTINFO))
+      ts_flags |= SOF_TIMESTAMPING_OPT_PKTINFO;
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_TX_SWHW
+    if (check_timestamping_option(SOF_TIMESTAMPING_OPT_TX_SWHW))
+      ts_flags |= SOF_TIMESTAMPING_OPT_TX_SWHW;
+#endif
+  }
+
+  /* Enable IP_PKTINFO in messages looped back to the error queue */
+  ts_flags |= SOF_TIMESTAMPING_OPT_CMSG;
+
+  /* Kernels before 4.7 ignore timestamping flags set in control messages */
+  permanent_ts_options = !SYS_Linux_CheckKernelVersion(4, 7);
+
+  dummy_rxts_socket = INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_Finalise(void)
+{
+  struct Interface *iface;
+  unsigned int i;
+
+  if (dummy_rxts_socket != INVALID_SOCK_FD)
+    SCK_CloseSocket(dummy_rxts_socket);
+
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    iface = ARR_GetElement(interfaces, i);
+    SCH_RemoveTimeout(iface->poll_timeout_id);
+    HCL_DestroyInstance(iface->clock);
+    close(iface->phc_fd);
+  }
+
+  ARR_DestroyInstance(interfaces);
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_IsHwTsEnabled(void)
+{
+  return ARR_GetSize(interfaces) > 0;
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events)
+{
+  int val, flags;
+
+  if (!ts_flags)
+    return 0;
+
+  /* Enable SCM_TIMESTAMPING control messages and the socket's error queue in
+     order to receive our transmitted packets with more accurate timestamps */
+
+  val = 1;
+  flags = ts_flags;
+
+  if (client_only || permanent_ts_options)
+    flags |= ts_tx_flags;
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_SELECT_ERR_QUEUE, val)) {
+    ts_flags = 0;
+    return 0;
+  }
+
+  if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPING, flags)) {
+    ts_flags = 0;
+    return 0;
+  }
+
+  *events |= SCH_FILE_EXCEPTION;
+  return 1;
+}
+
+/* ================================================== */
+
+static struct Interface *
+get_interface(int if_index)
+{
+  struct Interface *iface;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(interfaces); i++) {
+    iface = ARR_GetElement(interfaces, i);
+    if (iface->if_index != if_index)
+      continue;
+
+    return iface;
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+poll_timeout(void *arg)
+{
+  struct Interface *iface = arg;
+  struct timespec now;
+
+  iface->poll_timeout_id = 0;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  poll_phc(iface, &now);
+}
+
+/* ================================================== */
+
+static void
+poll_phc(struct Interface *iface, struct timespec *now)
+{
+  struct timespec sample_phc_ts, sample_sys_ts, sample_local_ts;
+  struct timespec phc_readings[PHC_READINGS][3];
+  double phc_err, local_err, interval;
+  int n_readings;
+
+  if (!HCL_NeedsNewSample(iface->clock, now))
+    return;
+
+  DEBUG_LOG("Polling PHC on %s%s",
+            iface->name, iface->poll_timeout_id != 0 ? " before timeout" : "");
+
+  n_readings = SYS_Linux_GetPHCReadings(iface->phc_fd, iface->phc_nocrossts,
+                                        &iface->phc_mode, PHC_READINGS, phc_readings);
+
+  /* Add timeout for the next poll in case no HW timestamp will be captured
+     between the minpoll and maxpoll.  Separate reading of different PHCs to
+     avoid long intervals between handling I/O events. */
+  SCH_RemoveTimeout(iface->poll_timeout_id);
+  interval = UTI_Log2ToDouble(iface->maxpoll);
+  iface->poll_timeout_id = SCH_AddTimeoutInClass(interval, interval /
+                                                   ARR_GetSize(interfaces) / 4, 0.1,
+                                                 SCH_PhcPollClass, poll_timeout, iface);
+
+  if (n_readings <= 0)
+    return;
+
+  if (!HCL_ProcessReadings(iface->clock, n_readings, phc_readings,
+                           &sample_phc_ts, &sample_sys_ts, &phc_err))
+    return;
+
+  LCL_CookTime(&sample_sys_ts, &sample_local_ts, &local_err);
+  HCL_AccumulateSample(iface->clock, &sample_phc_ts, &sample_local_ts, phc_err + local_err);
+
+  update_interface_speed(iface);
+}
+
+/* ================================================== */
+
+static void
+process_hw_timestamp(struct Interface *iface, struct timespec *hw_ts,
+                     NTP_Local_Timestamp *local_ts, int rx_ntp_length, int family,
+                     int l2_length)
+{
+  double rx_correction, ts_delay, local_err;
+  struct timespec ts;
+
+  poll_phc(iface, &local_ts->ts);
+
+  /* We need to transpose RX timestamps as hardware timestamps are normally
+     preamble timestamps and RX timestamps in NTP are supposed to be trailer
+     timestamps.  If we don't know the length of the packet at layer 2, we
+     make an assumption that UDP data start at the same position as in the
+     last transmitted packet which had a HW TX timestamp. */
+  if (rx_ntp_length && iface->link_speed) {
+    if (!l2_length)
+      l2_length = (family == IPADDR_INET4 ? iface->l2_udp4_ntp_start :
+                   iface->l2_udp6_ntp_start) + rx_ntp_length;
+
+    /* Include the frame check sequence (FCS) */
+    l2_length += 4;
+
+    rx_correction = l2_length / (1.0e6 / 8 * iface->link_speed);
+
+    UTI_AddDoubleToTimespec(hw_ts, rx_correction, hw_ts);
+  }
+
+  if (!HCL_CookTime(iface->clock, hw_ts, &ts, &local_err))
+    return;
+
+  if (!rx_ntp_length && iface->tx_comp)
+    UTI_AddDoubleToTimespec(&ts, iface->tx_comp, &ts);
+  else if (rx_ntp_length && iface->rx_comp)
+    UTI_AddDoubleToTimespec(&ts, -iface->rx_comp, &ts);
+
+  ts_delay = UTI_DiffTimespecsToDouble(&local_ts->ts, &ts);
+
+  if (fabs(ts_delay) > MAX_TS_DELAY) {
+    DEBUG_LOG("Unacceptable timestamp delay %.9f", ts_delay);
+    return;
+  }
+
+  local_ts->ts = ts;
+  local_ts->err = local_err;
+  local_ts->source = NTP_TS_HARDWARE;
+}
+
+/* ================================================== */
+
+static void
+process_sw_timestamp(struct timespec *sw_ts, NTP_Local_Timestamp *local_ts)
+{
+  double ts_delay, local_err;
+  struct timespec ts;
+
+  LCL_CookTime(sw_ts, &ts, &local_err);
+
+  ts_delay = UTI_DiffTimespecsToDouble(&local_ts->ts, &ts);
+
+  if (fabs(ts_delay) > MAX_TS_DELAY) {
+    DEBUG_LOG("Unacceptable timestamp delay %.9f", ts_delay);
+    return;
+  }
+
+  local_ts->ts = ts;
+  local_ts->err = local_err;
+  local_ts->source = NTP_TS_KERNEL;
+}
+
+/* ================================================== */
+/* Extract UDP data from a layer 2 message.  Supported is Ethernet
+   with optional VLAN tags. */
+
+static int
+extract_udp_data(unsigned char *msg, NTP_Remote_Address *remote_addr, int len)
+{
+  unsigned char *msg_start = msg;
+
+  remote_addr->ip_addr.family = IPADDR_UNSPEC;
+  remote_addr->port = 0;
+
+  /* Skip MACs */
+  if (len < 12)
+    return 0;
+  len -= 12, msg += 12;
+
+  /* Skip VLAN tag(s) if present */
+  while (len >= 4 && msg[0] == 0x81 && msg[1] == 0x00)
+    len -= 4, msg += 4;
+
+  /* Skip IPv4 or IPv6 ethertype */
+  if (len < 2 || !((msg[0] == 0x08 && msg[1] == 0x00) ||
+                   (msg[0] == 0x86 && msg[1] == 0xdd)))
+    return 0;
+  len -= 2, msg += 2;
+
+  /* Parse destination address and port from IPv4/IPv6 and UDP headers */
+  if (len >= 20 && msg[0] >> 4 == 4) {
+    int ihl = (msg[0] & 0xf) * 4;
+    uint32_t addr;
+
+    if (len < ihl + 8 || msg[9] != 17)
+      return 0;
+
+    memcpy(&addr, msg + 16, sizeof (addr));
+    remote_addr->ip_addr.addr.in4 = ntohl(addr);
+    remote_addr->port = ntohs(*(uint16_t *)(msg + ihl + 2));
+    remote_addr->ip_addr.family = IPADDR_INET4;
+    len -= ihl + 8, msg += ihl + 8;
+#ifdef FEAT_IPV6
+  } else if (len >= 48 && msg[0] >> 4 == 6) {
+    int eh_len, next_header = msg[6];
+
+    memcpy(&remote_addr->ip_addr.addr.in6, msg + 24, sizeof (remote_addr->ip_addr.addr.in6));
+    len -= 40, msg += 40;
+
+    /* Skip IPv6 extension headers if present */
+    while (next_header != 17) {
+      switch (next_header) {
+        case 44:  /* Fragment Header */
+          /* Process only the first fragment */
+          if (ntohs(*(uint16_t *)(msg + 2)) >> 3 != 0)
+            return 0;
+          eh_len = 8;
+          break;
+        case 0:   /* Hop-by-Hop Options */
+        case 43:  /* Routing Header */
+        case 60:  /* Destination Options */
+        case 135: /* Mobility Header */
+          eh_len = 8 * (msg[1] + 1);
+          break;
+        case 51:  /* Authentication Header */
+          eh_len = 4 * (msg[1] + 2);
+          break;
+        default:
+          return 0;
+      }
+
+      if (eh_len < 8 || len < eh_len + 8)
+        return 0;
+
+      next_header = msg[0];
+      len -= eh_len, msg += eh_len;
+    }
+
+    remote_addr->port = ntohs(*(uint16_t *)(msg + 2));
+    remote_addr->ip_addr.family = IPADDR_INET6;
+    len -= 8, msg += 8;
+#endif
+  } else {
+    return 0;
+  }
+
+  /* Move the message to fix alignment of its fields */
+  if (len > 0)
+    memmove(msg_start, msg, len);
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
+                         NTP_Local_Timestamp *local_ts, int event)
+{
+  struct Interface *iface;
+  int is_tx, ts_if_index, l2_length;
+
+  is_tx = event == SCH_FILE_EXCEPTION;
+  iface = NULL;
+
+  ts_if_index = message->timestamp.if_index;
+  if (ts_if_index == INVALID_IF_INDEX)
+    ts_if_index = message->if_index;
+  l2_length = message->timestamp.l2_length;
+
+  if (!UTI_IsZeroTimespec(&message->timestamp.hw)) {
+    iface = get_interface(ts_if_index);
+    if (iface) {
+      process_hw_timestamp(iface, &message->timestamp.hw, local_ts, !is_tx ? message->length : 0,
+                           message->remote_addr.ip.ip_addr.family, l2_length);
+    } else {
+      DEBUG_LOG("HW clock not found for interface %d", ts_if_index);
+    }
+  }
+
+  if (local_ts->source == NTP_TS_DAEMON && !UTI_IsZeroTimespec(&message->timestamp.kernel) &&
+      (!is_tx || UTI_IsZeroTimespec(&message->timestamp.hw))) {
+    process_sw_timestamp(&message->timestamp.kernel, local_ts);
+  }
+
+  /* If the kernel is slow with enabling RX timestamping, open a dummy
+     socket to keep the kernel RX timestamping permanently enabled */
+  if (!is_tx && local_ts->source == NTP_TS_DAEMON && ts_flags) {
+    DEBUG_LOG("Missing kernel RX timestamp");
+    if (dummy_rxts_socket == INVALID_SOCK_FD)
+      dummy_rxts_socket = open_dummy_socket();
+  }
+
+  /* Return the message if it's not received from the error queue */
+  if (!is_tx)
+    return 0;
+
+  /* The data from the error queue includes all layers up to UDP.  We have to
+     extract the UDP data and also the destination address with port as there
+     currently doesn't seem to be a better way to get them both. */
+  l2_length = message->length;
+  message->length = extract_udp_data(message->data, &message->remote_addr.ip, message->length);
+
+  DEBUG_LOG("Extracted message for %s fd=%d len=%d",
+            UTI_IPSockAddrToString(&message->remote_addr.ip),
+            local_addr->sock_fd, message->length);
+
+  /* Update assumed position of UDP data at layer 2 for next received packet */
+  if (iface && message->length) {
+    if (message->remote_addr.ip.ip_addr.family == IPADDR_INET4)
+      iface->l2_udp4_ntp_start = l2_length - message->length;
+    else if (message->remote_addr.ip.ip_addr.family == IPADDR_INET6)
+      iface->l2_udp6_ntp_start = l2_length - message->length;
+  }
+
+  /* Drop the message if it has no timestamp or its processing failed */
+  if (local_ts->source == NTP_TS_DAEMON) {
+    DEBUG_LOG("Missing TX timestamp");
+    return 1;
+  }
+
+  if (!NIO_UnwrapMessage(message, local_addr->sock_fd))
+    return 1;
+
+  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet))
+    return 1;
+
+  NSR_ProcessTx(&message->remote_addr.ip, local_addr, local_ts, message->data, message->length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd)
+{
+  if (!ts_flags)
+    return;
+
+  /* Check if TX timestamping is disabled on this socket */
+  if (permanent_ts_options || !NIO_IsServerSocket(sock_fd))
+    return;
+
+  message->timestamp.tx_flags = ts_tx_flags;
+}
diff --git a/ntp_io_linux.h b/ntp_io_linux.h
new file mode 100644
index 0000000..7978889
--- /dev/null
+++ b/ntp_io_linux.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the Linux-specific NTP socket I/O bits.
+  */
+
+#ifndef GOT_NTP_IO_LINUX_H
+#define GOT_NTP_IO_LINUX_H
+
+#include "socket.h"
+
+extern void NIO_Linux_Initialise(void);
+
+extern void NIO_Linux_Finalise(void);
+
+extern int NIO_Linux_IsHwTsEnabled(void);
+
+extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);
+
+extern int NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
+                                    NTP_Local_Timestamp *local_ts, int event);
+
+extern void NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd);
+
+#endif
diff --git a/ntp_signd.c b/ntp_signd.c
new file mode 100644
index 0000000..77b3249
--- /dev/null
+++ b/ntp_signd.c
@@ -0,0 +1,341 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Support for MS-SNTP authentication in Samba (ntp_signd)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "conf.h"
+#include "logging.h"
+#include "ntp_io.h"
+#include "ntp_signd.h"
+#include "sched.h"
+#include "socket.h"
+#include "util.h"
+
+/* Declarations per samba/source4/librpc/idl/ntp_signd.idl */
+
+#define SIGND_VERSION 0
+
+typedef enum {
+  SIGN_TO_CLIENT = 0,
+  ASK_SERVER_TO_SIGN = 1,
+  CHECK_SERVER_SIGNATURE = 2,
+  SIGNING_SUCCESS = 3,
+  SIGNING_FAILURE = 4,
+} SigndOp;
+
+typedef struct {
+  uint32_t length;
+  uint32_t version;
+  uint32_t op;
+  uint16_t packet_id;
+  uint16_t _pad;
+  uint32_t key_id;
+  NTP_Packet packet_to_sign;
+} SigndRequest;
+
+typedef struct {
+  uint32_t length;
+  uint32_t version;
+  uint32_t op;
+  uint32_t packet_id;
+  NTP_Packet signed_packet;
+} SigndResponse;
+
+typedef struct {
+  NTP_Remote_Address remote_addr;
+  NTP_Local_Address local_addr;
+
+  int sent;
+  int received;
+  int request_length;
+  struct timespec request_ts;
+  SigndRequest request;
+  SigndResponse response;
+} SignInstance;
+
+/* As the communication with ntp_signd is asynchronous, incoming packets are
+   saved in a queue in order to avoid loss when they come in bursts */
+
+#define MAX_QUEUE_LENGTH 16U
+#define NEXT_QUEUE_INDEX(index) (((index) + 1) % MAX_QUEUE_LENGTH)
+#define IS_QUEUE_EMPTY() (queue_head == queue_tail)
+
+/* Fixed-size array of SignInstance */
+static ARR_Instance queue;
+static unsigned int queue_head;
+static unsigned int queue_tail;
+
+#define INVALID_SOCK_FD (-6)
+
+/* Unix domain socket connected to ntp_signd */
+static int sock_fd;
+
+/* Flag indicating if the MS-SNTP authentication is enabled */
+static int enabled;
+
+/* ================================================== */
+
+static void read_write_socket(int sock_fd, int event, void *anything);
+
+/* ================================================== */
+
+static void
+close_socket(void)
+{
+  SCH_RemoveFileHandler(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  sock_fd = INVALID_SOCK_FD;
+
+  /* Empty the queue */
+  queue_head = queue_tail = 0;
+}
+
+/* ================================================== */
+
+static int
+open_socket(void)
+{
+  char path[PATH_MAX];
+
+  if (sock_fd != INVALID_SOCK_FD)
+    return 1;
+
+  if (snprintf(path, sizeof (path), "%s/socket", CNF_GetNtpSigndSocket()) >= sizeof (path)) {
+    DEBUG_LOG("signd socket path too long");
+    return 0;
+  }
+
+  sock_fd = SCK_OpenUnixStreamSocket(path, NULL, 0);
+  if (sock_fd < 0) {
+    sock_fd = INVALID_SOCK_FD;
+    return 0;
+  }
+
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_write_socket, NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_response(SignInstance *inst)
+{
+  struct timespec ts;
+  double delay;
+
+  if (ntohs(inst->request.packet_id) != ntohl(inst->response.packet_id)) {
+    DEBUG_LOG("Invalid response ID");
+    return;
+  }
+
+  if (ntohl(inst->response.op) != SIGNING_SUCCESS) {
+    DEBUG_LOG("Signing failed");
+    return;
+  }
+
+  /* Check if the file descriptor is still valid */
+  if (!NIO_IsServerSocket(inst->local_addr.sock_fd)) {
+    DEBUG_LOG("Invalid NTP socket");
+    return;
+  }
+
+  SCH_GetLastEventTime(NULL, NULL, &ts);
+  delay = UTI_DiffTimespecsToDouble(&ts, &inst->request_ts);
+
+  DEBUG_LOG("Signing succeeded (delay %f)", delay);
+
+  /* Send the signed NTP packet */
+  NIO_SendPacket(&inst->response.signed_packet, &inst->remote_addr, &inst->local_addr,
+                 ntohl(inst->response.length) + sizeof (inst->response.length) -
+                 offsetof(SigndResponse, signed_packet), 0);
+}
+
+/* ================================================== */
+
+static void
+read_write_socket(int sock_fd, int event, void *anything)
+{
+  SignInstance *inst;
+  uint32_t response_length;
+  int s;
+
+  inst = ARR_GetElement(queue, queue_head);
+
+  if (event == SCH_FILE_OUTPUT) {
+    assert(!IS_QUEUE_EMPTY());
+    assert(inst->sent < inst->request_length);
+
+    if (!inst->sent)
+      SCH_GetLastEventTime(NULL, NULL, &inst->request_ts);
+
+    s = SCK_Send(sock_fd, (char *)&inst->request + inst->sent,
+                 inst->request_length - inst->sent, 0);
+
+    if (s < 0) {
+      close_socket();
+      return;
+    }
+
+    inst->sent += s;
+
+    /* Try again later if the request is not complete yet */
+    if (inst->sent < inst->request_length)
+      return;
+
+    /* Disable output and wait for a response */
+    SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 0);
+  }
+
+  if (event == SCH_FILE_INPUT) {
+    if (IS_QUEUE_EMPTY()) {
+        DEBUG_LOG("Unexpected signd response");
+        close_socket();
+        return;
+    }
+
+    assert(inst->received < sizeof (inst->response));
+    s = SCK_Receive(sock_fd, (char *)&inst->response + inst->received,
+                    sizeof (inst->response) - inst->received, 0);
+
+    if (s <= 0) {
+      close_socket();
+      return;
+    }
+
+    inst->received += s;
+
+    if (inst->received < sizeof (inst->response.length))
+      return;
+
+    response_length = ntohl(inst->response.length) + sizeof (inst->response.length);
+
+    if (response_length < offsetof(SigndResponse, signed_packet) ||
+        response_length > sizeof (SigndResponse)) {
+      DEBUG_LOG("Invalid response length");
+      close_socket();
+      return;
+    }
+
+    /* Wait for more data if not complete yet */
+    if (inst->received < response_length)
+      return;
+
+    process_response(inst);
+
+    /* Move the head and enable output for the next packet */
+    queue_head = NEXT_QUEUE_INDEX(queue_head);
+    if (!IS_QUEUE_EMPTY())
+      SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 1);
+  }
+}
+
+/* ================================================== */
+
+void
+NSD_Initialise()
+{
+  sock_fd = INVALID_SOCK_FD;
+  enabled = CNF_GetNtpSigndSocket() && CNF_GetNtpSigndSocket()[0];
+
+  if (!enabled)
+    return;
+
+  queue = ARR_CreateInstance(sizeof (SignInstance));
+  ARR_SetSize(queue, MAX_QUEUE_LENGTH);
+  queue_head = queue_tail = 0;
+
+  LOG(LOGS_INFO, "MS-SNTP authentication enabled");
+}
+
+/* ================================================== */
+
+void
+NSD_Finalise()
+{
+  if (!enabled)
+    return;
+  if (sock_fd != INVALID_SOCK_FD)
+    close_socket();
+  ARR_DestroyInstance(queue);
+}
+
+/* ================================================== */
+
+int
+NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                      NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
+{
+  SignInstance *inst;
+
+  if (!enabled) {
+    DEBUG_LOG("signd disabled");
+    return 0;
+  }
+
+  if (queue_head == NEXT_QUEUE_INDEX(queue_tail)) {
+    DEBUG_LOG("signd queue full");
+    return 0;
+  }
+
+  if (info->length != NTP_HEADER_LENGTH) {
+    DEBUG_LOG("Invalid packet length");
+    return 0;
+  }
+
+  if (!open_socket())
+    return 0;
+
+  inst = ARR_GetElement(queue, queue_tail);
+  inst->remote_addr = *remote_addr;
+  inst->local_addr = *local_addr;
+  inst->sent = 0;
+  inst->received = 0;
+  inst->request_length = offsetof(SigndRequest, packet_to_sign) + info->length;
+
+  /* The length field doesn't include itself */
+  inst->request.length = htonl(inst->request_length - sizeof (inst->request.length));
+  inst->request.version = htonl(SIGND_VERSION);
+  inst->request.op = htonl(SIGN_TO_CLIENT);
+  inst->request.packet_id = htons(queue_tail);
+  inst->request._pad = 0;
+  inst->request.key_id = htonl(key_id);
+
+  memcpy(&inst->request.packet_to_sign, packet, info->length);
+
+  /* Enable output if there was no pending request */
+  if (IS_QUEUE_EMPTY())
+    SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_OUTPUT, 1);
+
+  queue_tail = NEXT_QUEUE_INDEX(queue_tail);
+
+  DEBUG_LOG("Packet added to signd queue (%u:%u)", queue_head, queue_tail);
+
+  return 1;
+}
diff --git a/ntp_signd.h b/ntp_signd.h
new file mode 100644
index 0000000..d333c9a
--- /dev/null
+++ b/ntp_signd.h
@@ -0,0 +1,42 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for MS-SNTP authentication via Samba (ntp_signd) */
+
+#ifndef GOT_NTP_SIGND_H
+#define GOT_NTP_SIGND_H
+
+#include "addressing.h"
+#include "ntp.h"
+
+/* Initialisation function */
+extern void NSD_Initialise(void);
+
+/* Finalisation function */
+extern void NSD_Finalise(void);
+
+/* Function to sign an NTP packet and send it */
+extern int NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                                 NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr);
+
+#endif
diff --git a/ntp_sources.c b/ntp_sources.c
new file mode 100644
index 0000000..28af1c1
--- /dev/null
+++ b/ntp_sources.c
@@ -0,0 +1,1536 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2012, 2014, 2016, 2020-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Functions which manage the pool of NTP sources that we are currently
+  a client of or peering with.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "conf.h"
+#include "ntp_sources.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "util.h"
+#include "logging.h"
+#include "local.h"
+#include "memory.h"
+#include "nameserv_async.h"
+#include "privops.h"
+#include "sched.h"
+
+/* ================================================== */
+
+/* Maximum number of sources */
+#define MAX_SOURCES 65536
+
+/* Record type private to this file, used to store information about
+   particular sources */
+typedef struct {
+  NTP_Remote_Address *remote_addr; /* The address of this source, non-NULL
+                                      means this slot in table is in use
+                                      (an IPADDR_ID address means the address
+                                      is not resolved yet) */
+  NCR_Instance data;            /* Data for the protocol engine for this source */
+  char *name;                   /* Name of the source as it was specified
+                                   (may be an IP address) */
+  IPAddr resolved_addr;         /* Address resolved from the name, which can be
+                                   different from remote_addr (e.g. NTS-KE) */
+  int pool_id;                  /* ID of the pool from which was this source
+                                   added or INVALID_POOL */
+  int tentative;                /* Flag indicating there was no valid response
+                                   received from the source yet */
+  uint32_t conf_id;             /* Configuration ID, which can be shared with
+                                   different sources in case of a pool */
+  double last_resolving;        /* Time of last name resolving (monotonic) */
+} SourceRecord;
+
+/* Hash table of SourceRecord, its size is a power of two and it's never
+   more than half full */
+static ARR_Instance records;
+
+/* Number of sources in the hash table */
+static int n_sources;
+
+/* Flag indicating new sources will be started automatically when added */
+static int auto_start_sources = 0;
+
+/* Flag indicating a record is currently being modified */
+static int record_lock;
+
+/* Last assigned address ID */
+static uint32_t last_address_id = 0;
+
+/* Last assigned configuration ID */
+static uint32_t last_conf_id = 0;
+
+/* Source scheduled for name resolving (first resolving or replacement) */
+struct UnresolvedSource {
+  /* Current address of the source (IPADDR_ID is used for a single source
+     with unknown address and IPADDR_UNSPEC for a pool of sources) */
+  NTP_Remote_Address address;
+  /* ID of the pool if not a single source */
+  int pool_id;
+  /* Name to be resolved */
+  char *name;
+  /* Flag indicating addresses should be used in a random order */
+  int random_order;
+  /* Flag indicating current address should be replaced only if it is
+     no longer returned by the resolver */
+  int refreshment;
+  /* Next unresolved source in the list */
+  struct UnresolvedSource *next;
+};
+
+#define RESOLVE_INTERVAL_UNIT 7
+#define MIN_RESOLVE_INTERVAL 2
+#define MAX_RESOLVE_INTERVAL 9
+#define MAX_REPLACEMENT_INTERVAL 9
+
+static struct UnresolvedSource *unresolved_sources = NULL;
+static int resolving_interval = 0;
+static int resolving_restart = 0;
+static SCH_TimeoutID resolving_id;
+static struct UnresolvedSource *resolving_source = NULL;
+static NSR_SourceResolvingEndHandler resolving_end_handler = NULL;
+
+#define MAX_POOL_SOURCES 16
+#define INVALID_POOL (-1)
+
+/* Pool of sources with the same name */
+struct SourcePool {
+  /* Number of all sources from the pool */
+  int sources;
+  /* Number of sources with unresolved address */
+  int unresolved_sources;
+  /* Number of non-tentative sources */
+  int confirmed_sources;
+  /* Maximum number of confirmed sources */
+  int max_sources;
+};
+
+/* Array of SourcePool (indexed by their ID) */
+static ARR_Instance pools;
+
+/* Requested update of a source's address */
+struct AddressUpdate {
+  NTP_Remote_Address old_address;
+  NTP_Remote_Address new_address;
+};
+
+/* Update saved when record_lock is true */
+static struct AddressUpdate saved_address_update;
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void resolve_sources(void);
+static void rehash_records(void);
+static void handle_saved_address_update(void);
+static void clean_source_record(SourceRecord *record);
+static void remove_pool_sources(int pool_id, int tentative, int unresolved);
+static void remove_unresolved_source(struct UnresolvedSource *us);
+
+static void
+slew_sources(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *anything);
+
+/* ================================================== */
+
+/* Flag indicating whether module is initialised */
+static int initialised = 0;
+
+/* ================================================== */
+
+static SourceRecord *
+get_record(unsigned index)
+{
+  return (SourceRecord *)ARR_GetElement(records, index);
+}
+
+/* ================================================== */
+
+static struct SourcePool *
+get_pool(unsigned index)
+{
+  return (struct SourcePool *)ARR_GetElement(pools, index);
+}
+
+/* ================================================== */
+
+void
+NSR_Initialise(void)
+{
+  n_sources = 0;
+  resolving_id = 0;
+  initialised = 1;
+
+  records = ARR_CreateInstance(sizeof (SourceRecord));
+  rehash_records();
+
+  pools = ARR_CreateInstance(sizeof (struct SourcePool));
+
+  LCL_AddParameterChangeHandler(slew_sources, NULL);
+}
+
+/* ================================================== */
+
+void
+NSR_Finalise(void)
+{
+  NSR_RemoveAllSources();
+
+  LCL_RemoveParameterChangeHandler(slew_sources, NULL);
+
+  ARR_DestroyInstance(records);
+  ARR_DestroyInstance(pools);
+
+  SCH_RemoveTimeout(resolving_id);
+  while (unresolved_sources)
+    remove_unresolved_source(unresolved_sources);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+/* Find a slot matching an IP address.  It is assumed that there can
+   only ever be one record for a particular IP address. */
+
+static int
+find_slot(IPAddr *ip_addr, int *slot)
+{
+  SourceRecord *record;
+  uint32_t hash;
+  unsigned int i, size;
+
+  size = ARR_GetSize(records);
+
+  *slot = 0;
+  
+  switch (ip_addr->family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+    case IPADDR_ID:
+      break;
+    default:
+      return 0;
+  }
+
+  hash = UTI_IPToHash(ip_addr);
+
+  for (i = 0; i < size / 2; i++) {
+    /* Use quadratic probing */
+    *slot = (hash + (i + i * i) / 2) % size;
+    record = get_record(*slot);
+
+    if (!record->remote_addr)
+      break;
+
+    if (UTI_CompareIPs(&record->remote_addr->ip_addr, ip_addr, NULL) == 0)
+      return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+/* Find a slot matching an IP address and port. The function returns:
+   0 => IP not matched, empty slot returned if a valid address was provided
+   1 => Only IP matched, port doesn't match
+   2 => Both IP and port matched. */
+
+static int
+find_slot2(NTP_Remote_Address *remote_addr, int *slot)
+{
+  if (!find_slot(&remote_addr->ip_addr, slot))
+    return 0;
+
+  return get_record(*slot)->remote_addr->port == remote_addr->port ? 2 : 1;
+}
+
+/* ================================================== */
+/* Check if hash table of given size is sufficient to contain sources */
+
+static int
+check_hashtable_size(unsigned int sources, unsigned int size)
+{
+  return sources * 2 <= size;
+}
+
+/* ================================================== */
+
+static void
+rehash_records(void)
+{
+  SourceRecord *temp_records;
+  unsigned int i, old_size, new_size;
+  int slot;
+
+  assert(!record_lock);
+
+  old_size = ARR_GetSize(records);
+
+  temp_records = MallocArray(SourceRecord, old_size);
+  memcpy(temp_records, ARR_GetElements(records), old_size * sizeof (SourceRecord));
+
+  /* The size of the hash table is always a power of two */
+  for (new_size = 1; !check_hashtable_size(n_sources, new_size); new_size *= 2)
+    ;
+
+  ARR_SetSize(records, new_size);
+
+  for (i = 0; i < new_size; i++)
+    get_record(i)->remote_addr = NULL;
+
+  for (i = 0; i < old_size; i++) {
+    if (!temp_records[i].remote_addr)
+      continue;
+
+    if (find_slot2(temp_records[i].remote_addr, &slot) != 0)
+      assert(0);
+
+    *get_record(slot) = temp_records[i];
+  }
+
+  Free(temp_records);
+}
+
+/* ================================================== */
+
+static void
+log_source(SourceRecord *record, int addition, int once_per_pool)
+{
+  int pool, log_addr;
+  char *ip_str;
+
+  if (once_per_pool && record->pool_id != INVALID_POOL) {
+    if (get_pool(record->pool_id)->sources > 1)
+      return;
+    pool = 1;
+    log_addr = 0;
+  } else {
+    ip_str = UTI_IPToString(&record->remote_addr->ip_addr);
+    pool = 0;
+    log_addr = strcmp(record->name, ip_str) != 0;
+  }
+
+  LOG(LOG_GetContextSeverity(LOGC_Command | LOGC_SourceFile), "%s %s %s%s%s%s",
+      addition ? "Added" : "Removed", pool ? "pool" : "source",
+      log_addr ? ip_str : record->name,
+      log_addr ? " (" : "", log_addr ? record->name : "", log_addr ? ")" : "");
+}
+
+/* ================================================== */
+
+/* Procedure to add a new source */
+static NSR_Status
+add_source(NTP_Remote_Address *remote_addr, char *name, NTP_Source_Type type,
+           SourceParameters *params, int pool_id, uint32_t conf_id)
+{
+  SourceRecord *record;
+  int slot;
+
+  assert(initialised);
+
+  /* Find empty bin & check that we don't have the address already */
+  if (find_slot2(remote_addr, &slot) != 0) {
+    return NSR_AlreadyInUse;
+  } else if (!name && !UTI_IsIPReal(&remote_addr->ip_addr)) {
+    /* Name is required for non-real addresses */
+    return NSR_InvalidName;
+  } else if (n_sources >= MAX_SOURCES) {
+    return NSR_TooManySources;
+  } else {
+    if (remote_addr->ip_addr.family != IPADDR_INET4 &&
+        remote_addr->ip_addr.family != IPADDR_INET6 &&
+        remote_addr->ip_addr.family != IPADDR_ID) {
+      return NSR_InvalidAF;
+    } else {
+      n_sources++;
+
+      if (!check_hashtable_size(n_sources, ARR_GetSize(records))) {
+        rehash_records();
+        if (find_slot2(remote_addr, &slot) != 0)
+          assert(0);
+      }
+
+      assert(!record_lock);
+      record_lock = 1;
+
+      record = get_record(slot);
+      record->name = Strdup(name ? name : UTI_IPToString(&remote_addr->ip_addr));
+      record->data = NCR_CreateInstance(remote_addr, type, params, record->name);
+      record->remote_addr = NCR_GetRemoteAddress(record->data);
+      record->resolved_addr = remote_addr->ip_addr;
+      record->pool_id = pool_id;
+      record->tentative = 1;
+      record->conf_id = conf_id;
+      record->last_resolving = SCH_GetLastEventMonoTime();
+
+      record_lock = 0;
+
+      if (record->pool_id != INVALID_POOL) {
+        get_pool(record->pool_id)->sources++;
+        if (!UTI_IsIPReal(&remote_addr->ip_addr))
+          get_pool(record->pool_id)->unresolved_sources++;
+      }
+
+      if (auto_start_sources && UTI_IsIPReal(&remote_addr->ip_addr))
+        NCR_StartInstance(record->data);
+
+      log_source(record, 1, 1);
+
+      /* The new instance is allowed to change its address immediately */
+      handle_saved_address_update();
+
+      return NSR_Success;
+    }
+  }
+}
+
+/* ================================================== */
+
+static NSR_Status
+change_source_address(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr,
+                      int replacement)
+{
+  int slot1, slot2, found;
+  SourceRecord *record;
+  LOG_Severity severity;
+  char *name;
+
+  found = find_slot2(old_addr, &slot1);
+  if (found != 2)
+    return NSR_NoSuchSource;
+
+  /* Make sure there is no other source using the new address (with the same
+     or different port), but allow a source to have its port changed */
+  found = find_slot2(new_addr, &slot2);
+  if (found == 2 || (found != 0 && slot1 != slot2))
+    return NSR_AlreadyInUse;
+
+  assert(!record_lock);
+  record_lock = 1;
+
+  record = get_record(slot1);
+  NCR_ChangeRemoteAddress(record->data, new_addr, !replacement);
+  if (replacement)
+    record->resolved_addr = new_addr->ip_addr;
+
+  if (record->remote_addr != NCR_GetRemoteAddress(record->data) ||
+      UTI_CompareIPs(&record->remote_addr->ip_addr, &new_addr->ip_addr, NULL) != 0)
+    assert(0);
+
+  if (!UTI_IsIPReal(&old_addr->ip_addr) && UTI_IsIPReal(&new_addr->ip_addr)) {
+    if (auto_start_sources)
+      NCR_StartInstance(record->data);
+    if (record->pool_id != INVALID_POOL)
+      get_pool(record->pool_id)->unresolved_sources--;
+  }
+
+  if (!record->tentative) {
+    record->tentative = 1;
+
+    if (record->pool_id != INVALID_POOL)
+      get_pool(record->pool_id)->confirmed_sources--;
+  }
+
+  record_lock = 0;
+
+  name = record->name;
+  severity = UTI_IsIPReal(&old_addr->ip_addr) ? LOGS_INFO : LOGS_DEBUG;
+
+  if (found == 0) {
+    /* The hash table must be rebuilt for the changed address */
+    rehash_records();
+
+    LOG(severity, "Source %s %s %s (%s)", UTI_IPToString(&old_addr->ip_addr),
+        replacement ? "replaced with" : "changed to",
+        UTI_IPToString(&new_addr->ip_addr), name);
+  } else {
+    LOG(severity, "Source %s (%s) changed port to %d",
+        UTI_IPToString(&new_addr->ip_addr), name, new_addr->port);
+  }
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+static void
+handle_saved_address_update(void)
+{
+  if (!UTI_IsIPReal(&saved_address_update.old_address.ip_addr))
+    return;
+
+  if (change_source_address(&saved_address_update.old_address,
+                            &saved_address_update.new_address, 0) != NSR_Success)
+    /* This is expected to happen only if the old address is wrong */
+    LOG(LOGS_ERR, "Could not change %s to %s",
+        UTI_IPSockAddrToString(&saved_address_update.old_address),
+        UTI_IPSockAddrToString(&saved_address_update.new_address));
+
+  saved_address_update.old_address.ip_addr.family = IPADDR_UNSPEC;
+}
+
+/* ================================================== */
+
+static int
+replace_source_connectable(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr)
+{
+  if (!NIO_IsServerConnectable(new_addr)) {
+    DEBUG_LOG("%s not connectable", UTI_IPToString(&new_addr->ip_addr));
+    return 0;
+  }
+
+  if (change_source_address(old_addr, new_addr, 1) == NSR_AlreadyInUse)
+    return 0;
+
+  handle_saved_address_update();
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+process_resolved_name(struct UnresolvedSource *us, IPAddr *ip_addrs, int n_addrs)
+{
+  NTP_Remote_Address old_addr, new_addr;
+  SourceRecord *record;
+  unsigned short first = 0;
+  int i, j, slot;
+
+  /* Keep using the current address if it is being refreshed and it is
+     still included in the resolved addresses */
+  if (us->refreshment) {
+    assert(us->pool_id == INVALID_POOL);
+
+    for (i = 0; i < n_addrs; i++) {
+      if (find_slot2(&us->address, &slot) == 2 &&
+          UTI_CompareIPs(&get_record(slot)->resolved_addr, &ip_addrs[i], NULL) == 0) {
+        DEBUG_LOG("%s still fresh", UTI_IPToString(&us->address.ip_addr));
+        return;
+      }
+    }
+  }
+
+  if (us->random_order)
+    UTI_GetRandomBytes(&first, sizeof (first));
+
+  for (i = 0; i < n_addrs; i++) {
+    new_addr.ip_addr = ip_addrs[((unsigned int)i + first) % n_addrs];
+
+    DEBUG_LOG("(%d) %s", i + 1, UTI_IPToString(&new_addr.ip_addr));
+
+    if (us->pool_id != INVALID_POOL) {
+      /* In the pool resolving mode, try to replace a source from
+         the pool which does not have a real address yet */
+      for (j = 0; j < ARR_GetSize(records); j++) {
+        record = get_record(j);
+        if (!record->remote_addr || record->pool_id != us->pool_id ||
+            UTI_IsIPReal(&record->remote_addr->ip_addr))
+          continue;
+        old_addr = *record->remote_addr;
+        new_addr.port = old_addr.port;
+        if (replace_source_connectable(&old_addr, &new_addr))
+          ;
+        break;
+      }
+    } else {
+      new_addr.port = us->address.port;
+      if (replace_source_connectable(&us->address, &new_addr))
+        break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+is_resolved(struct UnresolvedSource *us)
+{
+  int slot;
+
+  if (us->pool_id != INVALID_POOL) {
+    return get_pool(us->pool_id)->unresolved_sources <= 0;
+  } else {
+    /* If the address is no longer present, it was removed or replaced
+       (i.e. resolved) */
+    return find_slot2(&us->address, &slot) == 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+resolve_sources_timeout(void *arg)
+{
+  resolving_id = 0;
+  resolve_sources();
+}
+
+/* ================================================== */
+
+static void
+name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *anything)
+{
+  struct UnresolvedSource *us, *next;
+
+  us = (struct UnresolvedSource *)anything;
+
+  assert(us == resolving_source);
+  assert(resolving_id == 0);
+
+  DEBUG_LOG("%s resolved to %d addrs", us->name, n_addrs);
+
+  switch (status) {
+    case DNS_TryAgain:
+      break;
+    case DNS_Success:
+      process_resolved_name(us, ip_addrs, n_addrs);
+      break;
+    case DNS_Failure:
+      LOG(LOGS_WARN, "Invalid host %s", us->name);
+      break;
+    default:
+      assert(0);
+  }
+
+  next = us->next;
+
+  /* Don't repeat the resolving if it (permanently) failed, it was a
+     replacement of a real address, or all addresses are already resolved */
+  if (status == DNS_Failure || UTI_IsIPReal(&us->address.ip_addr) || is_resolved(us))
+    remove_unresolved_source(us);
+
+  /* If a restart was requested and this was the last source in the list,
+     start with the first source again (if there still is one) */
+  if (!next && resolving_restart) {
+    next = unresolved_sources;
+    resolving_restart = 0;
+  }
+
+  resolving_source = next;
+
+  if (next) {
+    /* Continue with the next source in the list */
+    DEBUG_LOG("resolving %s", next->name);
+    DNS_Name2IPAddressAsync(next->name, name_resolve_handler, next);
+  } else {
+    /* This was the last source in the list. If some sources couldn't
+       be resolved, try again in exponentially increasing interval. */
+    if (unresolved_sources) {
+      resolving_interval = CLAMP(MIN_RESOLVE_INTERVAL, resolving_interval + 1,
+                                 MAX_RESOLVE_INTERVAL);
+      resolving_id = SCH_AddTimeoutByDelay(RESOLVE_INTERVAL_UNIT * (1 << resolving_interval),
+                                           resolve_sources_timeout, NULL);
+    } else {
+      resolving_interval = 0;
+    }
+
+    /* This round of resolving is done */
+    if (resolving_end_handler)
+      (resolving_end_handler)();
+  }
+}
+
+/* ================================================== */
+
+static void
+resolve_sources(void)
+{
+  struct UnresolvedSource *us, *next, *i;
+
+  assert(!resolving_source);
+
+  /* Remove sources that don't need to be resolved anymore */
+  for (i = unresolved_sources; i; i = next) {
+    next = i->next;
+    if (is_resolved(i))
+      remove_unresolved_source(i);
+  }
+
+  if (!unresolved_sources)
+    return;
+
+  PRV_ReloadDNS();
+
+  /* Start with the first source in the list, name_resolve_handler
+     will iterate over the rest */
+  us = unresolved_sources;
+
+  resolving_source = us;
+  DEBUG_LOG("resolving %s", us->name);
+  DNS_Name2IPAddressAsync(us->name, name_resolve_handler, us);
+}
+
+/* ================================================== */
+
+static void
+append_unresolved_source(struct UnresolvedSource *us)
+{
+  struct UnresolvedSource **i;
+
+  for (i = &unresolved_sources; *i; i = &(*i)->next)
+    ;
+  *i = us;
+  us->next = NULL;
+}
+
+/* ================================================== */
+
+static void
+remove_unresolved_source(struct UnresolvedSource *us)
+{
+  struct UnresolvedSource **i;
+
+  for (i = &unresolved_sources; *i; i = &(*i)->next) {
+    if (*i == us) {
+      *i = us->next;
+      Free(us->name);
+      Free(us);
+      break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int get_unused_pool_id(void)
+{
+  struct UnresolvedSource *us;
+  int i;
+
+  for (i = 0; i < ARR_GetSize(pools); i++) {
+    if (get_pool(i)->sources > 0)
+      continue;
+
+    /* Make sure there is no name waiting to be resolved using this pool */
+    for (us = unresolved_sources; us; us = us->next) {
+      if (us->pool_id == i)
+        break;
+    }
+    if (us)
+      continue;
+
+    return i;
+  }
+
+  return INVALID_POOL;
+}
+
+/* ================================================== */
+
+static uint32_t
+get_next_conf_id(uint32_t *conf_id)
+{
+  last_conf_id++;
+
+  if (conf_id)
+    *conf_id = last_conf_id;
+
+  return last_conf_id;
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+              SourceParameters *params, uint32_t *conf_id)
+{
+  return add_source(remote_addr, NULL, type, params, INVALID_POOL,
+                    get_next_conf_id(conf_id));
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                    SourceParameters *params, uint32_t *conf_id)
+{
+  struct UnresolvedSource *us;
+  struct SourcePool *sp;
+  NTP_Remote_Address remote_addr;
+  int i, new_sources, pool_id;
+  uint32_t cid;
+
+  /* If the name is an IP address, add the source with the address directly */
+  if (UTI_StringToIP(name, &remote_addr.ip_addr)) {
+    remote_addr.port = port;
+    return add_source(&remote_addr, name, type, params, INVALID_POOL,
+                      get_next_conf_id(conf_id));
+  }
+
+  /* Make sure the name is at least printable and has no spaces */
+  for (i = 0; name[i] != '\0'; i++) {
+    if (!isgraph((unsigned char)name[i]))
+      return NSR_InvalidName;
+  }
+
+  us = MallocNew(struct UnresolvedSource);
+  us->name = Strdup(name);
+  us->random_order = 0;
+  us->refreshment = 0;
+
+  remote_addr.ip_addr.family = IPADDR_ID;
+  remote_addr.ip_addr.addr.id = ++last_address_id;
+  remote_addr.port = port;
+
+  if (!pool) {
+    us->pool_id = INVALID_POOL;
+    us->address = remote_addr;
+    new_sources = 1;
+  } else {
+    pool_id = get_unused_pool_id();
+    if (pool_id != INVALID_POOL) {
+      sp = get_pool(pool_id);
+    } else {
+      sp = ARR_GetNewElement(pools);
+      pool_id = ARR_GetSize(pools) - 1;
+    }
+
+    sp->sources = 0;
+    sp->unresolved_sources = 0;
+    sp->confirmed_sources = 0;
+    sp->max_sources = CLAMP(1, params->max_sources, MAX_POOL_SOURCES);
+    us->pool_id = pool_id;
+    us->address.ip_addr.family = IPADDR_UNSPEC;
+    new_sources = MIN(2 * sp->max_sources, MAX_POOL_SOURCES);
+  }
+
+  append_unresolved_source(us);
+
+  cid = get_next_conf_id(conf_id);
+
+  for (i = 0; i < new_sources; i++) {
+    if (i > 0)
+      remote_addr.ip_addr.addr.id = ++last_address_id;
+    if (add_source(&remote_addr, name, type, params, us->pool_id, cid) != NSR_Success)
+      return NSR_TooManySources;
+  }
+
+  return NSR_UnresolvedName;
+}
+
+/* ================================================== */
+
+void
+NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler)
+{
+  resolving_end_handler = handler;
+}
+
+/* ================================================== */
+
+void
+NSR_ResolveSources(void)
+{
+  /* Try to resolve unresolved sources now */
+  if (unresolved_sources) {
+    /* Allow only one resolving to be running at a time */
+    if (!resolving_source) {
+      if (resolving_id != 0) {
+        SCH_RemoveTimeout(resolving_id);
+        resolving_id = 0;
+        resolving_interval--;
+      }
+      resolve_sources();
+    } else {
+      /* Try again as soon as the current resolving ends */
+      resolving_restart = 1;
+    }
+  } else {
+    /* No unresolved sources, we are done */
+    if (resolving_end_handler)
+      (resolving_end_handler)();
+  }
+}
+
+/* ================================================== */
+
+void NSR_StartSources(void)
+{
+  NTP_Remote_Address *addr;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    addr = get_record(i)->remote_addr;
+    if (!addr || !UTI_IsIPReal(&addr->ip_addr))
+      continue;
+    NCR_StartInstance(get_record(i)->data);
+  }
+}
+
+/* ================================================== */
+
+void NSR_AutoStartSources(void)
+{
+  auto_start_sources = 1;
+}
+
+/* ================================================== */
+
+static void
+clean_source_record(SourceRecord *record)
+{
+  assert(record->remote_addr);
+
+  if (record->pool_id != INVALID_POOL) {
+    struct SourcePool *pool = get_pool(record->pool_id);
+
+    pool->sources--;
+    if (!UTI_IsIPReal(&record->remote_addr->ip_addr))
+      pool->unresolved_sources--;
+    if (!record->tentative)
+      pool->confirmed_sources--;
+    if (pool->max_sources > pool->sources)
+      pool->max_sources = pool->sources;
+  }
+
+  record->remote_addr = NULL;
+  NCR_DestroyInstance(record->data);
+  Free(record->name);
+
+  n_sources--;
+}
+
+/* ================================================== */
+
+/* Procedure to remove a source.  We don't bother whether the port
+   address is matched - we're only interested in removing a record for
+   the right IP address. */
+NSR_Status
+NSR_RemoveSource(IPAddr *address)
+{
+  int slot;
+
+  assert(initialised);
+
+  if (find_slot(address, &slot) == 0)
+    return NSR_NoSuchSource;
+
+  log_source(get_record(slot), 0, 0);
+  clean_source_record(get_record(slot));
+
+  /* Rehash the table to make sure there are no broken probe sequences.
+     This is costly, but it's not expected to happen frequently. */
+
+  rehash_records();
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+void
+NSR_RemoveSourcesById(uint32_t conf_id)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr || record->conf_id != conf_id)
+      continue;
+    log_source(record, 0, 1);
+    clean_source_record(record);
+  }
+
+  rehash_records();
+}
+
+/* ================================================== */
+
+void
+NSR_RemoveAllSources(void)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+    clean_source_record(record);
+  }
+
+  rehash_records();
+}
+
+/* ================================================== */
+
+static void
+resolve_source_replacement(SourceRecord *record, int refreshment)
+{
+  struct UnresolvedSource *us;
+
+  DEBUG_LOG("%s %s (%s)", refreshment ? "refreshing" : "trying to replace",
+            UTI_IPToString(&record->remote_addr->ip_addr), record->name);
+
+  record->last_resolving = SCH_GetLastEventMonoTime();
+
+  us = MallocNew(struct UnresolvedSource);
+  us->name = Strdup(record->name);
+  /* Ignore the order of addresses from the resolver to not get
+     stuck with a pair of unreachable or otherwise unusable servers
+     (e.g. falsetickers) in case the order doesn't change, or a group
+     of servers if they are ordered by IP family */
+  us->random_order = 1;
+  us->refreshment = refreshment;
+  us->pool_id = INVALID_POOL;
+  us->address = *record->remote_addr;
+
+  append_unresolved_source(us);
+  NSR_ResolveSources();
+}
+
+/* ================================================== */
+
+void
+NSR_HandleBadSource(IPAddr *address)
+{
+  static double next_replacement = 0.0;
+  SourceRecord *record;
+  IPAddr ip_addr;
+  uint32_t rnd;
+  double now;
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return;
+
+  record = get_record(slot);
+
+  /* Don't try to replace a source specified by an IP address unless the
+     address changed since the source was added (e.g. by NTS-KE) */
+  if (UTI_StringToIP(record->name, &ip_addr) &&
+      UTI_CompareIPs(&record->remote_addr->ip_addr, &ip_addr, NULL) == 0)
+    return;
+
+  /* Don't resolve names too frequently */
+  now = SCH_GetLastEventMonoTime();
+  if (now < next_replacement) {
+    DEBUG_LOG("replacement postponed");
+    return;
+  }
+
+  UTI_GetRandomBytes(&rnd, sizeof (rnd));
+  next_replacement = now + ((double)rnd / (uint32_t)-1) *
+                     (RESOLVE_INTERVAL_UNIT * (1 << MAX_REPLACEMENT_INTERVAL));
+
+  resolve_source_replacement(record, 0);
+}
+
+/* ================================================== */
+
+static void
+maybe_refresh_source(void)
+{
+  static double last_refreshment = 0.0;
+  SourceRecord *record, *oldest_record;
+  int i, min_interval;
+  double now;
+
+  min_interval = CNF_GetRefresh();
+
+  now = SCH_GetLastEventMonoTime();
+  if (min_interval <= 0 || now < last_refreshment + min_interval)
+    return;
+
+  last_refreshment = now;
+
+  for (i = 0, oldest_record = NULL; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr || UTI_IsStringIP(record->name))
+      continue;
+
+    if (!oldest_record || oldest_record->last_resolving > record->last_resolving)
+      oldest_record = record;
+  }
+
+  if (!oldest_record)
+    return;
+
+  /* Check if the name wasn't already resolved in the last interval */
+  if (now < oldest_record->last_resolving + min_interval) {
+    last_refreshment = oldest_record->last_resolving;
+    return;
+  }
+
+  resolve_source_replacement(oldest_record, 1);
+}
+
+/* ================================================== */
+
+void
+NSR_RefreshAddresses(void)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+
+    resolve_source_replacement(record, 1);
+  }
+}
+
+/* ================================================== */
+
+NSR_Status
+NSR_UpdateSourceNtpAddress(NTP_Remote_Address *old_addr, NTP_Remote_Address *new_addr)
+{
+  int slot;
+
+  if (!UTI_IsIPReal(&old_addr->ip_addr) || !UTI_IsIPReal(&new_addr->ip_addr))
+    return NSR_InvalidAF;
+
+  if (UTI_CompareIPs(&old_addr->ip_addr, &new_addr->ip_addr, NULL) != 0 &&
+      find_slot(&new_addr->ip_addr, &slot))
+    return NSR_AlreadyInUse;
+
+  /* If a record is being modified (e.g. by change_source_address(), or the
+     source is just being created), postpone the change to avoid corruption */
+
+  if (!record_lock)
+    return change_source_address(old_addr, new_addr, 0);
+
+  if (UTI_IsIPReal(&saved_address_update.old_address.ip_addr))
+    return NSR_TooManySources;
+
+  saved_address_update.old_address = *old_addr;
+  saved_address_update.new_address = *new_addr;
+
+  return NSR_Success;
+}
+
+/* ================================================== */
+
+static void remove_pool_sources(int pool_id, int tentative, int unresolved)
+{
+  SourceRecord *record;
+  unsigned int i, removed;
+
+  for (i = removed = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+
+    if (!record->remote_addr || record->pool_id != pool_id)
+      continue;
+
+    if ((tentative && !record->tentative) ||
+        (unresolved && UTI_IsIPReal(&record->remote_addr->ip_addr)))
+      continue;
+
+    DEBUG_LOG("removing %ssource %s", tentative ? "tentative " : "",
+              UTI_IPToString(&record->remote_addr->ip_addr));
+
+    clean_source_record(record);
+    removed++;
+  }
+
+  if (removed)
+    rehash_records();
+}
+
+/* ================================================== */
+
+uint32_t
+NSR_GetLocalRefid(IPAddr *address)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  return NCR_GetLocalRefid(get_record(slot)->data);
+}
+
+/* ================================================== */
+
+char *
+NSR_GetName(IPAddr *address)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return NULL;
+
+  return get_record(slot)->name;
+}
+
+/* ================================================== */
+
+/* This routine is called by ntp_io when a new packet arrives off the network,
+   possibly with an authentication tail */
+void
+NSR_ProcessRx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+              NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length)
+{
+  SourceRecord *record;
+  struct SourcePool *pool;
+  int slot;
+
+  assert(initialised);
+
+  /* Avoid unnecessary lookup if the packet cannot be a response from our
+     source.  Otherwise, it must match both IP address and port number. */
+  if (NTP_LVM_TO_MODE(message->lvm) != MODE_CLIENT &&
+      find_slot2(remote_addr, &slot) == 2) {
+    record = get_record(slot);
+
+    if (!NCR_ProcessRxKnown(record->data, local_addr, rx_ts, message, length))
+      return;
+
+    if (record->tentative) {
+      /* This was the first good reply from the source */
+      record->tentative = 0;
+
+      if (record->pool_id != INVALID_POOL) {
+        pool = get_pool(record->pool_id);
+        pool->confirmed_sources++;
+
+        DEBUG_LOG("pool %s has %d confirmed sources", record->name, pool->confirmed_sources);
+
+        /* If the number of sources from the pool reached the configured
+           maximum, remove the remaining tentative sources */
+        if (pool->confirmed_sources >= pool->max_sources)
+          remove_pool_sources(record->pool_id, 1, 0);
+      }
+    }
+
+    maybe_refresh_source();
+  } else {
+    NCR_ProcessRxUnknown(remote_addr, local_addr, rx_ts, message, length);
+  }
+}
+
+/* ================================================== */
+
+void
+NSR_ProcessTx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+              NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
+{
+  SourceRecord *record;
+  int slot;
+
+  /* Avoid unnecessary lookup if the packet cannot be a request to our
+     source.  Otherwise, it must match both IP address and port number. */
+  if (NTP_LVM_TO_MODE(message->lvm) != MODE_SERVER &&
+      find_slot2(remote_addr, &slot) == 2) {
+    record = get_record(slot);
+    NCR_ProcessTxKnown(record->data, local_addr, tx_ts, message, length);
+  } else {
+    NCR_ProcessTxUnknown(remote_addr, local_addr, tx_ts, message, length);
+  }
+}
+
+/* ================================================== */
+
+static void
+slew_sources(struct timespec *raw,
+             struct timespec *cooked,
+             double dfreq,
+             double doffset,
+             LCL_ChangeType change_type,
+             void *anything)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      if (change_type == LCL_ChangeUnknownStep) {
+        NCR_ResetInstance(record->data);
+        NCR_ResetPoll(record->data);
+      } else {
+        NCR_SlewTimes(record->data, cooked, dfreq, doffset);
+      }
+    }
+  }
+}
+
+/* ================================================== */
+
+int
+NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity)
+{
+  SourceRecord *record, *syncpeer;
+  unsigned int i, any;
+
+  if (connectivity != SRC_OFFLINE)
+    NSR_ResolveSources();
+
+  any = 0;
+  syncpeer = NULL;
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      /* Ignore SRC_MAYBE_ONLINE connectivity change for unspecified unresolved
+         sources as they would always end up in the offline state */
+      if ((address->family == IPADDR_UNSPEC &&
+           (connectivity != SRC_MAYBE_ONLINE || UTI_IsIPReal(&record->remote_addr->ip_addr))) ||
+          !UTI_CompareIPs(&record->remote_addr->ip_addr, address, mask)) {
+        any = 1;
+        if (NCR_IsSyncPeer(record->data)) {
+          syncpeer = record;
+          continue;
+        }
+        NCR_SetConnectivity(record->data, connectivity);
+      }
+    }
+  }
+
+  /* Set the sync peer last to avoid unnecessary reference switching */
+  if (syncpeer)
+    NCR_SetConnectivity(syncpeer->data, connectivity);
+
+  return any;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMinpoll(IPAddr *address, int new_minpoll)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMinpoll(get_record(slot)->data, new_minpoll);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxpoll(get_record(slot)->data, new_maxpoll);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelay(get_record(slot)->data, new_max_delay);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelayratio(get_record(slot)->data, new_max_delay_ratio);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_dev_ratio)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMaxdelaydevratio(get_record(slot)->data, new_max_delay_dev_ratio);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyMinstratum(get_record(slot)->data, new_min_stratum);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_ModifyPolltarget(IPAddr *address, int new_poll_target)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_ModifyPolltarget(get_record(slot)->data, new_poll_target);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples,
+                        IPAddr *mask, IPAddr *address)
+{
+  SourceRecord *record;
+  unsigned int i;
+  int any;
+
+  any = 0;
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (record->remote_addr) {
+      if (address->family == IPADDR_UNSPEC ||
+          !UTI_CompareIPs(&record->remote_addr->ip_addr, address, mask)) {
+        any = 1;
+        NCR_InitiateSampleBurst(record->data, n_good_samples, n_total_samples);
+      }
+    }
+  }
+
+  return any;
+
+}
+
+/* ================================================== */
+/* The ip address is assumed to be completed on input, that is how we
+   identify the source record. */
+
+void
+NSR_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  int slot;
+
+  if (find_slot(&report->ip_addr, &slot)) {
+    NCR_ReportSource(get_record(slot)->data, report, now);
+  } else {
+    report->poll = 0;
+    report->latest_meas_ago = 0;
+  }
+}
+
+/* ================================================== */
+
+int
+NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report)
+{
+  int slot;
+
+  if (!find_slot(address, &slot))
+    return 0;
+
+  NCR_GetAuthReport(get_record(slot)->data, report);
+  return 1;
+}
+
+/* ================================================== */
+/* The ip address is assumed to be completed on input, that is how we
+   identify the source record. */
+
+int
+NSR_GetNTPReport(RPT_NTPReport *report)
+{
+  int slot;
+
+  if (!find_slot(&report->remote_addr, &slot))
+    return 0;
+
+  NCR_GetNTPReport(get_record(slot)->data, report);
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NSR_GetActivityReport(RPT_ActivityReport *report)
+{
+  SourceRecord *record;
+  unsigned int i;
+
+  report->online = 0;
+  report->offline = 0;
+  report->burst_online = 0;
+  report->burst_offline = 0;
+  report->unresolved = 0;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+
+    if (!UTI_IsIPReal(&record->remote_addr->ip_addr)) {
+      report->unresolved++;
+    } else {
+      NCR_IncrementActivityCounters(record->data, &report->online, &report->offline,
+                                    &report->burst_online, &report->burst_offline);
+    }
+  }
+}
+
+/* ================================================== */
+
+void
+NSR_DumpAuthData(void)
+{
+  SourceRecord *record;
+  int i;
+
+  for (i = 0; i < ARR_GetSize(records); i++) {
+    record = get_record(i);
+    if (!record->remote_addr)
+      continue;
+    NCR_DumpAuthData(record->data);
+  }
+}
diff --git a/ntp_sources.h b/ntp_sources.h
new file mode 100644
index 0000000..ba3b9c4
--- /dev/null
+++ b/ntp_sources.h
@@ -0,0 +1,152 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for the part of the software that deals with the set of
+  current NTP servers and peers, which can resolve an IP address into
+  a source record for further processing.
+
+  */
+
+#ifndef GOT_NTP_SOURCES_H
+#define GOT_NTP_SOURCES_H
+
+#include "ntp.h"
+#include "addressing.h"
+#include "srcparams.h"
+#include "ntp_core.h"
+#include "reports.h"
+
+/* Status values returned by operations that indirectly result from user
+   input. */
+typedef enum {
+  NSR_Success, /* Operation successful */
+  NSR_NoSuchSource, /* Remove - attempt to remove a source that is not known */
+  NSR_AlreadyInUse, /* AddSource - attempt to add a source that is already known */ 
+  NSR_TooManySources, /* AddSource - too many sources already present */
+  NSR_InvalidAF, /* AddSource - attempt to add a source with invalid address family */
+  NSR_InvalidName, /* AddSourceByName - attempt to add a source with invalid name */
+  NSR_UnresolvedName, /* AddSourceByName - name will be resolved later */
+} NSR_Status;
+
+/* Procedure to add a new server or peer source. */
+extern NSR_Status NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                                SourceParameters *params, uint32_t *conf_id);
+
+/* Procedure to add a new server, peer source, or pool of servers specified by
+   name instead of address.  The name is resolved in exponentially increasing
+   intervals until it succeeds or fails with a non-temporary error.  If the
+   name is an address, it is equivalent to NSR_AddSource(). */
+extern NSR_Status NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                                      SourceParameters *params, uint32_t *conf_id);
+
+/* Function type for handlers to be called back when an attempt
+ * (possibly unsuccessful) to resolve unresolved sources ends */
+typedef void (*NSR_SourceResolvingEndHandler)(void);
+
+/* Set the handler, or NULL to disable the notification */
+extern void NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler);
+
+/* Procedure to start resolving unresolved sources */
+extern void NSR_ResolveSources(void);
+
+/* Procedure to start all sources */
+extern void NSR_StartSources(void);
+
+/* Start new sources automatically */
+extern void NSR_AutoStartSources(void);
+
+/* Procedure to remove a source */
+extern NSR_Status NSR_RemoveSource(IPAddr *address);
+
+/* Procedure to remove all sources matching a configuration ID */
+extern void NSR_RemoveSourcesById(uint32_t conf_id);
+
+/* Procedure to remove all sources */
+extern void NSR_RemoveAllSources(void);
+
+/* Procedure to try to find a replacement for a bad source */
+extern void NSR_HandleBadSource(IPAddr *address);
+
+/* Procedure to resolve all names again */
+extern void NSR_RefreshAddresses(void);
+
+/* Procedure to update the address of a source.  The update may be
+   postponed. */
+extern NSR_Status NSR_UpdateSourceNtpAddress(NTP_Remote_Address *old_addr,
+                                             NTP_Remote_Address *new_addr);
+
+/* Procedure to get local reference ID corresponding to a source */
+extern uint32_t NSR_GetLocalRefid(IPAddr *address);
+
+/* Procedure to get the name of a source as it was specified (it may be
+   an IP address) */
+extern char *NSR_GetName(IPAddr *address);
+
+/* This routine is called by ntp_io when a new packet arrives off the network */
+extern void NSR_ProcessRx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                          NTP_Local_Timestamp *rx_ts, NTP_Packet *message, int length);
+
+/* This routine is called by ntp_io when a packet was sent to the network and
+   an accurate transmit timestamp was captured */
+extern void NSR_ProcessTx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
+                          NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length);
+
+/* Initialisation function */
+extern void NSR_Initialise(void);
+
+/* Finalisation function */
+extern void NSR_Finalise(void);
+
+/* This routine is used to indicate that sources whose IP addresses
+   match a particular subnet should be set online or offline.  It returns
+   a flag indicating whether any hosts matched the address. */
+extern int NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity);
+
+extern int NSR_ModifyMinpoll(IPAddr *address, int new_minpoll);
+
+extern int NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll);
+
+extern int NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay);
+
+extern int NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio);
+
+extern int NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_ratio);
+
+extern int NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum);
+
+extern int NSR_ModifyPolltarget(IPAddr *address, int new_poll_target);
+
+extern int NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples, IPAddr *mask, IPAddr *address);
+
+extern void NSR_ReportSource(RPT_SourceReport *report, struct timespec *now);
+
+extern int NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report);
+
+extern int NSR_GetNTPReport(RPT_NTPReport *report);
+
+extern void NSR_GetActivityReport(RPT_ActivityReport *report);
+
+extern void NSR_DumpAuthData(void);
+
+#endif /* GOT_NTP_SOURCES_H */
diff --git a/nts_ke.h b/nts_ke.h
new file mode 100644
index 0000000..e7497af
--- /dev/null
+++ b/nts_ke.h
@@ -0,0 +1,81 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS Key Establishment protocol
+  */
+
+#ifndef GOT_NTS_KE_H
+#define GOT_NTS_KE_H
+
+#include "siv.h"
+
+#define NKE_PORT                        4460
+
+#define NKE_RECORD_CRITICAL_BIT         (1U << 15)
+#define NKE_RECORD_END_OF_MESSAGE       0
+#define NKE_RECORD_NEXT_PROTOCOL        1
+#define NKE_RECORD_ERROR                2
+#define NKE_RECORD_WARNING              3
+#define NKE_RECORD_AEAD_ALGORITHM       4
+#define NKE_RECORD_COOKIE               5
+#define NKE_RECORD_NTPV4_SERVER_NEGOTIATION 6
+#define NKE_RECORD_NTPV4_PORT_NEGOTIATION 7
+
+#define NKE_NEXT_PROTOCOL_NTPV4         0
+
+#define NKE_ERROR_UNRECOGNIZED_CRITICAL_RECORD 0
+#define NKE_ERROR_BAD_REQUEST           1
+#define NKE_ERROR_INTERNAL_SERVER_ERROR 2
+
+#define NKE_ALPN_NAME                   "ntske/1"
+#define NKE_EXPORTER_LABEL              "EXPORTER-network-time-security"
+#define NKE_EXPORTER_CONTEXT_C2S        "\x0\x0\x0\xf\x0"
+#define NKE_EXPORTER_CONTEXT_S2C        "\x0\x0\x0\xf\x1"
+
+#define NKE_MAX_MESSAGE_LENGTH          16384
+#define NKE_MAX_RECORD_BODY_LENGTH      256
+#define NKE_MAX_COOKIE_LENGTH           256
+#define NKE_MAX_COOKIES                 8
+#define NKE_MAX_KEY_LENGTH SIV_MAX_KEY_LENGTH
+
+#define NKE_RETRY_FACTOR2_CONNECT       4
+#define NKE_RETRY_FACTOR2_TLS           10
+#define NKE_MAX_RETRY_INTERVAL2         19
+
+typedef struct {
+  int length;
+  unsigned char key[NKE_MAX_KEY_LENGTH];
+} NKE_Key;
+
+typedef struct {
+  SIV_Algorithm algorithm;
+  NKE_Key c2s;
+  NKE_Key s2c;
+} NKE_Context;
+
+typedef struct {
+  int length;
+  unsigned char cookie[NKE_MAX_COOKIE_LENGTH];
+} NKE_Cookie;
+
+#endif
diff --git a/nts_ke_client.c b/nts_ke_client.c
new file mode 100644
index 0000000..3891f71
--- /dev/null
+++ b/nts_ke_client.c
@@ -0,0 +1,457 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE client
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_client.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "nameserv_async.h"
+#include "nts_ke_session.h"
+#include "siv.h"
+#include "socket.h"
+#include "util.h"
+
+#define CLIENT_TIMEOUT 16.0
+
+struct NKC_Instance_Record {
+  char *name;
+  IPSockAddr address;
+  NKSN_Credentials credentials;
+  NKSN_Instance session;
+  int destroying;
+  int got_response;
+  int resolving_name;
+
+  NKE_Context context;
+  NKE_Cookie cookies[NKE_MAX_COOKIES];
+  int num_cookies;
+  char server_name[NKE_MAX_RECORD_BODY_LENGTH + 2];
+  IPSockAddr ntp_address;
+};
+
+/* ================================================== */
+
+static NKSN_Credentials default_credentials = NULL;
+static int default_credentials_refs = 0;
+
+/* ================================================== */
+
+static void
+name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *arg)
+{
+  NKC_Instance inst = arg;
+  int i;
+
+  inst->resolving_name = 0;
+
+  if (inst->destroying) {
+    Free(inst);
+    return;
+  }
+
+  if (status != DNS_Success || n_addrs < 1) {
+    LOG(LOGS_ERR, "Could not resolve NTP server %s from %s", inst->server_name, inst->name);
+    /* Force restart */
+    inst->got_response = 0;
+    return;
+  }
+
+  inst->ntp_address.ip_addr = ip_addrs[0];
+
+  /* Prefer an address in the same family as the NTS-KE server */
+  for (i = 0; i < n_addrs; i++) {
+    DEBUG_LOG("%s resolved to %s", inst->server_name, UTI_IPToString(&ip_addrs[i]));
+    if (ip_addrs[i].family == inst->address.ip_addr.family) {
+      inst->ntp_address.ip_addr = ip_addrs[i];
+      break;
+    }
+  }
+}
+
+/* ================================================== */
+
+static int
+prepare_request(NKC_Instance inst)
+{
+  NKSN_Instance session = inst->session;
+  uint16_t data[2];
+  int length;
+
+  NKSN_BeginMessage(session);
+
+  data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, sizeof (data[0])))
+    return 0;
+
+  length = 0;
+  if (SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0)
+    data[length++] = htons(AEAD_AES_128_GCM_SIV);
+  if (SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) > 0)
+    data[length++] = htons(AEAD_AES_SIV_CMAC_256);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data,
+                      length * sizeof (data[0])))
+    return 0;
+
+  if (!NKSN_EndMessage(session))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_response(NKC_Instance inst)
+{
+  int next_protocol = -1, aead_algorithm = -1, error = 0;
+  int i, critical, type, length;
+  uint16_t data[NKE_MAX_RECORD_BODY_LENGTH / sizeof (uint16_t)];
+
+  assert(NKE_MAX_COOKIE_LENGTH <= NKE_MAX_RECORD_BODY_LENGTH);
+  assert(sizeof (data) % sizeof (uint16_t) == 0);
+  assert(sizeof (uint16_t) == 2);
+
+  inst->num_cookies = 0;
+  inst->ntp_address.ip_addr.family = IPADDR_UNSPEC;
+  inst->ntp_address.port = 0;
+  inst->server_name[0] = '\0';
+
+  while (!error) {
+    if (!NKSN_GetRecord(inst->session, &critical, &type, &length, &data, sizeof (data)))
+      break;
+
+    if (length > sizeof (data)) {
+      DEBUG_LOG("Record too long type=%d length=%d critical=%d", type, length, critical);
+      if (critical)
+        error = 1;
+      continue;
+    }
+
+    switch (type) {
+      case NKE_RECORD_NEXT_PROTOCOL:
+        if (!critical || length != 2 || ntohs(data[0]) != NKE_NEXT_PROTOCOL_NTPV4) {
+          DEBUG_LOG("Unexpected NTS-KE next protocol");
+          error = 1;
+          break;
+        }
+        next_protocol = NKE_NEXT_PROTOCOL_NTPV4;
+        break;
+      case NKE_RECORD_AEAD_ALGORITHM:
+        if (length != 2 || (ntohs(data[0]) != AEAD_AES_SIV_CMAC_256 &&
+                            ntohs(data[0]) != AEAD_AES_128_GCM_SIV) ||
+            SIV_GetKeyLength(ntohs(data[0])) <= 0) {
+          DEBUG_LOG("Unexpected NTS-KE AEAD algorithm");
+          error = 1;
+          break;
+        }
+        aead_algorithm = ntohs(data[0]);
+        inst->context.algorithm = aead_algorithm;
+        break;
+      case NKE_RECORD_ERROR:
+        if (length == 2)
+          DEBUG_LOG("NTS-KE error %d", ntohs(data[0]));
+        error = 1;
+        break;
+      case NKE_RECORD_WARNING:
+        if (length == 2)
+          DEBUG_LOG("NTS-KE warning %d", ntohs(data[0]));
+        error = 1;
+        break;
+      case NKE_RECORD_COOKIE:
+        DEBUG_LOG("Got cookie length=%d", length);
+
+        if (length < 1 || length > NKE_MAX_COOKIE_LENGTH || length % 4 != 0 ||
+            inst->num_cookies >= NKE_MAX_COOKIES) {
+          DEBUG_LOG("Unexpected length/cookie");
+          break;
+        }
+
+        assert(NKE_MAX_COOKIE_LENGTH == sizeof (inst->cookies[inst->num_cookies].cookie));
+        assert(NKE_MAX_COOKIES == sizeof (inst->cookies) /
+                                  sizeof (inst->cookies[inst->num_cookies]));
+        inst->cookies[inst->num_cookies].length = length;
+        memcpy(inst->cookies[inst->num_cookies].cookie, data, length);
+
+        inst->num_cookies++;
+        break;
+      case NKE_RECORD_NTPV4_SERVER_NEGOTIATION:
+        if (length < 1 || length >= sizeof (inst->server_name)) {
+          DEBUG_LOG("Invalid server name");
+          error = 1;
+          break;
+        }
+
+        memcpy(inst->server_name, data, length);
+        inst->server_name[length] = '\0';
+
+        /* Make sure the name is printable and has no spaces */
+        for (i = 0; i < length && isgraph((unsigned char)inst->server_name[i]); i++)
+          ;
+        if (i != length) {
+          DEBUG_LOG("Invalid server name");
+          error = 1;
+          break;
+        }
+
+        DEBUG_LOG("Negotiated server %s", inst->server_name);
+        break;
+      case NKE_RECORD_NTPV4_PORT_NEGOTIATION:
+        if (length != 2) {
+          DEBUG_LOG("Invalid port");
+          error = 1;
+          break;
+        }
+        inst->ntp_address.port = ntohs(data[0]);
+        DEBUG_LOG("Negotiated port %d", inst->ntp_address.port);
+        break;
+      default:
+        DEBUG_LOG("Unknown record type=%d length=%d critical=%d", type, length, critical);
+        if (critical)
+          error = 1;
+    }
+  }
+
+  DEBUG_LOG("NTS-KE response: error=%d next=%d aead=%d",
+            error, next_protocol, aead_algorithm);
+
+  if (error || inst->num_cookies == 0 ||
+      next_protocol != NKE_NEXT_PROTOCOL_NTPV4 ||
+      aead_algorithm < 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+handle_message(void *arg)
+{
+  NKC_Instance inst = arg;
+
+  if (!process_response(inst)) {
+    LOG(LOGS_ERR, "Received invalid NTS-KE response from %s", inst->name);
+    return 0;
+  }
+
+  if (!NKSN_GetKeys(inst->session, inst->context.algorithm,
+                    &inst->context.c2s, &inst->context.s2c))
+    return 0;
+
+  if (inst->server_name[0] != '\0') {
+    if (inst->resolving_name)
+      return 0;
+    if (!UTI_StringToIP(inst->server_name, &inst->ntp_address.ip_addr)) {
+      int length = strlen(inst->server_name);
+
+      /* Add a trailing dot if not present to force the name to be
+         resolved as a fully qualified domain name */
+      if (length < 1 || length + 1 >= sizeof (inst->server_name))
+        return 0;
+      if (inst->server_name[length - 1] != '.') {
+        inst->server_name[length] = '.';
+        inst->server_name[length + 1] = '\0';
+      }
+
+      DNS_Name2IPAddressAsync(inst->server_name, name_resolve_handler, inst);
+      inst->resolving_name = 1;
+    }
+  }
+
+  inst->got_response = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+NKC_Instance
+NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set)
+{
+  const char **trusted_certs;
+  uint32_t *certs_ids;
+  NKC_Instance inst;
+  int n_certs;
+
+  inst = MallocNew(struct NKC_Instance_Record);
+
+  inst->address = *address;
+  inst->name = Strdup(name);
+  inst->session = NKSN_CreateInstance(0, inst->name, handle_message, inst);
+  inst->resolving_name = 0;
+  inst->destroying = 0;
+  inst->got_response = 0;
+
+  n_certs = CNF_GetNtsTrustedCertsPaths(&trusted_certs, &certs_ids);
+
+  /* Share the credentials among clients using the default set of trusted
+     certificates, which likely contains most certificates */
+  if (cert_set == 0) {
+    if (!default_credentials)
+      default_credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                             n_certs, cert_set);
+    inst->credentials = default_credentials;
+    if (default_credentials)
+      default_credentials_refs++;
+  } else {
+    inst->credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                         n_certs, cert_set);
+  }
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NKC_DestroyInstance(NKC_Instance inst)
+{
+  NKSN_DestroyInstance(inst->session);
+
+  Free(inst->name);
+
+  if (inst->credentials) {
+    if (inst->credentials == default_credentials) {
+      default_credentials_refs--;
+      if (default_credentials_refs <= 0) {
+        NKSN_DestroyCertCredentials(default_credentials);
+        default_credentials = NULL;
+      }
+    } else {
+      NKSN_DestroyCertCredentials(inst->credentials);
+    }
+  }
+
+  /* If the asynchronous resolver is running, let the handler free
+     the instance later */
+  if (inst->resolving_name) {
+    inst->destroying = 1;
+    return;
+  }
+
+  Free(inst);
+}
+
+/* ================================================== */
+
+int
+NKC_Start(NKC_Instance inst)
+{
+  IPSockAddr local_addr;
+  char label[512], *iface;
+  int sock_fd;
+
+  assert(!NKC_IsActive(inst));
+
+  inst->got_response = 0;
+
+  if (!inst->credentials) {
+    DEBUG_LOG("Missing client credentials");
+    return 0;
+  }
+
+  /* Don't try to connect if missing the algorithm which all servers
+     are required to support */
+  if (SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) <= 0) {
+    LOG(LOGS_ERR, "Missing AES-SIV-CMAC-256");
+    return 0;
+  }
+
+  /* Follow the bindacqaddress and bindacqdevice settings */
+  CNF_GetBindAcquisitionAddress(inst->address.ip_addr.family, &local_addr.ip_addr);
+  local_addr.port = 0;
+  iface = CNF_GetBindAcquisitionInterface();
+
+  /* Make a label containing both the address and name of the server */
+  if (snprintf(label, sizeof (label), "%s (%s)",
+               UTI_IPSockAddrToString(&inst->address), inst->name) >= sizeof (label))
+    ;
+
+  sock_fd = SCK_OpenTcpSocket(&inst->address, &local_addr, iface, 0);
+  if (sock_fd < 0) {
+    LOG(LOGS_ERR, "Could not connect to %s", label);
+    return 0;
+  }
+
+  /* Start an NTS-KE session */
+  if (!NKSN_StartSession(inst->session, sock_fd, label, inst->credentials, CLIENT_TIMEOUT)) {
+    SCK_CloseSocket(sock_fd);
+    return 0;
+  }
+
+  /* Send a request */
+  if (!prepare_request(inst)) {
+    DEBUG_LOG("Could not prepare NTS-KE request");
+    NKSN_StopSession(inst->session);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKC_IsActive(NKC_Instance inst)
+{
+  return !NKSN_IsStopped(inst->session) || inst->resolving_name;
+}
+
+/* ================================================== */
+
+int
+NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
+               NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+               IPSockAddr *ntp_address)
+{
+  int i;
+
+  if (!inst->got_response || inst->resolving_name)
+    return 0;
+
+  *context = inst->context;
+
+  for (i = 0; i < inst->num_cookies && i < max_cookies; i++)
+    cookies[i] = inst->cookies[i];
+  *num_cookies = i;
+
+  *ntp_address = inst->ntp_address;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKC_GetRetryFactor(NKC_Instance inst)
+{
+  return NKSN_GetRetryFactor(inst->session);
+}
diff --git a/nts_ke_client.h b/nts_ke_client.h
new file mode 100644
index 0000000..a1bedb6
--- /dev/null
+++ b/nts_ke_client.h
@@ -0,0 +1,56 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE client
+  */
+
+#ifndef GOT_NTS_KE_CLIENT_H
+#define GOT_NTS_KE_CLIENT_H
+
+#include "addressing.h"
+#include "nts_ke.h"
+
+typedef struct NKC_Instance_Record *NKC_Instance;
+
+/* Create a client NTS-KE instance */
+extern NKC_Instance NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set);
+
+/* Destroy an instance */
+extern void NKC_DestroyInstance(NKC_Instance inst);
+
+/* Connect to the server, start an NTS-KE session, send an NTS-KE request, and
+   process the response (asynchronously) */
+extern int NKC_Start(NKC_Instance inst);
+
+/* Check if the client is still running */
+extern int NKC_IsActive(NKC_Instance inst);
+
+/* Get the NTS data if the session was successful */
+extern int NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
+                          NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+                          IPSockAddr *ntp_address);
+
+/* Get a factor to calculate retry interval (in log2 seconds) */
+extern int NKC_GetRetryFactor(NKC_Instance inst);
+
+#endif
diff --git a/nts_ke_server.c b/nts_ke_server.c
new file mode 100644
index 0000000..5e25c50
--- /dev/null
+++ b/nts_ke_server.c
@@ -0,0 +1,1034 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE server
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_server.h"
+
+#include "array.h"
+#include "conf.h"
+#include "clientlog.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp_core.h"
+#include "nts_ke_session.h"
+#include "privops.h"
+#include "siv.h"
+#include "socket.h"
+#include "sched.h"
+#include "sys.h"
+#include "util.h"
+
+#define SERVER_TIMEOUT 2.0
+
+#define MAX_COOKIE_NONCE_LENGTH 16
+
+#define KEY_ID_INDEX_BITS 2
+#define MAX_SERVER_KEYS (1U << KEY_ID_INDEX_BITS)
+#define FUTURE_KEYS 1
+
+#define DUMP_FILENAME "ntskeys"
+#define DUMP_IDENTIFIER "NKS1\n"
+#define OLD_DUMP_IDENTIFIER "NKS0\n"
+
+#define INVALID_SOCK_FD (-7)
+
+typedef struct {
+  uint32_t key_id;
+} ServerCookieHeader;
+
+typedef struct {
+  uint32_t id;
+  unsigned char key[SIV_MAX_KEY_LENGTH];
+  SIV_Algorithm siv_algorithm;
+  SIV_Instance siv;
+  int nonce_length;
+} ServerKey;
+
+typedef struct {
+  uint32_t key_id;
+  uint32_t siv_algorithm;
+  unsigned char key[SIV_MAX_KEY_LENGTH];
+  IPAddr client_addr;
+  uint16_t client_port;
+  uint16_t _pad;
+} HelperRequest;
+
+/* ================================================== */
+
+static ServerKey server_keys[MAX_SERVER_KEYS];
+static int current_server_key;
+static double last_server_key_ts;
+static int key_rotation_interval;
+
+static int server_sock_fd4;
+static int server_sock_fd6;
+
+static int helper_sock_fd;
+static int is_helper;
+
+static int initialised = 0;
+
+/* Array of NKSN instances */
+static ARR_Instance sessions;
+static NKSN_Credentials server_credentials;
+
+/* ================================================== */
+
+static int handle_message(void *arg);
+
+/* ================================================== */
+
+static int
+handle_client(int sock_fd, IPSockAddr *addr)
+{
+  NKSN_Instance inst, *instp;
+  int i;
+
+  /* Leave at least half of the descriptors which can handled by select()
+     to other use */
+  if (sock_fd > FD_SETSIZE / 2) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(addr), "too many descriptors");
+    return 0;
+  }
+
+  /* Find an unused server slot or one with an already stopped session */
+  for (i = 0, inst = NULL; i < ARR_GetSize(sessions); i++) {
+    instp = ARR_GetElement(sessions, i);
+    if (!*instp) {
+      /* NULL handler arg will be replaced with the session instance */
+      inst = NKSN_CreateInstance(1, NULL, handle_message, NULL);
+      *instp = inst;
+      break;
+    } else if (NKSN_IsStopped(*instp)) {
+      inst = *instp;
+      break;
+    }
+  }
+
+  if (!inst) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(addr), "too many connections");
+    return 0;
+  }
+
+  assert(server_credentials);
+
+  if (!NKSN_StartSession(inst, sock_fd, UTI_IPSockAddrToString(addr),
+                         server_credentials, SERVER_TIMEOUT))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+update_key_siv(ServerKey *key, SIV_Algorithm algorithm)
+{
+  if (!key->siv || key->siv_algorithm != algorithm) {
+    if (key->siv)
+      SIV_DestroyInstance(key->siv);
+    key->siv_algorithm = algorithm;
+    key->siv = SIV_CreateInstance(algorithm);
+    key->nonce_length = MIN(SIV_GetMaxNonceLength(key->siv), MAX_COOKIE_NONCE_LENGTH);
+  }
+
+  if (!key->siv || !SIV_SetKey(key->siv, key->key, SIV_GetKeyLength(key->siv_algorithm)))
+    LOG_FATAL("Could not set SIV key");
+}
+
+/* ================================================== */
+
+static void
+handle_helper_request(int fd, int event, void *arg)
+{
+  SCK_Message *message;
+  HelperRequest *req;
+  IPSockAddr client_addr;
+  ServerKey *key;
+  int sock_fd;
+
+  /* Receive the helper request with the NTS-KE session socket.
+     With multiple helpers EAGAIN errors are expected here. */
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message)
+    return;
+
+  sock_fd = message->descriptor;
+  if (sock_fd < 0) {
+    /* Message with no descriptor is a shutdown command */
+    SCH_QuitProgram();
+    return;
+  }
+
+  if (!initialised) {
+    DEBUG_LOG("Uninitialised helper");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  if (message->length != sizeof (HelperRequest))
+    LOG_FATAL("Invalid helper request");
+
+  req = message->data;
+
+  /* Extract the current server key and client address from the request */
+  key = &server_keys[current_server_key];
+  key->id = ntohl(req->key_id);
+  assert(sizeof (key->key) == sizeof (req->key));
+  memcpy(key->key, req->key, sizeof (key->key));
+  UTI_IPNetworkToHost(&req->client_addr, &client_addr.ip_addr);
+  client_addr.port = ntohs(req->client_port);
+
+  update_key_siv(key, ntohl(req->siv_algorithm));
+
+  if (!handle_client(sock_fd, &client_addr)) {
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  DEBUG_LOG("Accepted helper request fd=%d", sock_fd);
+}
+
+/* ================================================== */
+
+static void
+accept_connection(int listening_fd, int event, void *arg)
+{
+  SCK_Message message;
+  IPSockAddr addr;
+  int log_index, sock_fd;
+  struct timespec now;
+
+  sock_fd = SCK_AcceptConnection(listening_fd, &addr);
+  if (sock_fd < 0)
+    return;
+
+  if (!NCR_CheckAccessRestriction(&addr.ip_addr)) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(&addr), "access denied");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  log_index = CLG_LogServiceAccess(CLG_NTSKE, &addr.ip_addr, &now);
+  if (log_index >= 0 && CLG_LimitServiceRate(CLG_NTSKE, log_index)) {
+    DEBUG_LOG("Rejected connection from %s (%s)",
+              UTI_IPSockAddrToString(&addr), "rate limit");
+    SCK_CloseSocket(sock_fd);
+    return;
+  }
+
+  /* Pass the socket to a helper process if enabled.  Otherwise, handle the
+     client in the main process. */
+  if (helper_sock_fd != INVALID_SOCK_FD) {
+    HelperRequest req;
+
+    memset(&req, 0, sizeof (req));
+
+    /* Include the current server key and client address in the request */
+    req.key_id = htonl(server_keys[current_server_key].id);
+    req.siv_algorithm = htonl(server_keys[current_server_key].siv_algorithm);
+    assert(sizeof (req.key) == sizeof (server_keys[current_server_key].key));
+    memcpy(req.key, server_keys[current_server_key].key, sizeof (req.key));
+    UTI_IPHostToNetwork(&addr.ip_addr, &req.client_addr);
+    req.client_port = htons(addr.port);
+
+    SCK_InitMessage(&message, SCK_ADDR_UNSPEC);
+    message.data = &req;
+    message.length = sizeof (req);
+    message.descriptor = sock_fd;
+
+    errno = 0;
+    if (!SCK_SendMessage(helper_sock_fd, &message, SCK_FLAG_MSG_DESCRIPTOR)) {
+      /* If sending failed with EPIPE, it means all helpers closed their end of
+         the socket (e.g. due to a fatal error) */
+      if (errno == EPIPE)
+        LOG_FATAL("NTS-KE helpers failed");
+      SCK_CloseSocket(sock_fd);
+      return;
+    }
+
+    SCK_CloseSocket(sock_fd);
+  } else {
+    if (!handle_client(sock_fd, &addr)) {
+      SCK_CloseSocket(sock_fd);
+      return;
+    }
+  }
+
+  DEBUG_LOG("Accepted connection from %s fd=%d", UTI_IPSockAddrToString(&addr), sock_fd);
+}
+
+/* ================================================== */
+
+static int
+open_socket(int family)
+{
+  IPSockAddr local_addr;
+  int backlog, sock_fd;
+  char *iface;
+
+  if (!SCK_IsIpFamilyEnabled(family))
+    return INVALID_SOCK_FD;
+
+  CNF_GetBindAddress(family, &local_addr.ip_addr);
+  local_addr.port = CNF_GetNtsServerPort();
+  iface = CNF_GetBindNtpInterface();
+
+  sock_fd = SCK_OpenTcpSocket(NULL, &local_addr, iface, 0);
+  if (sock_fd < 0) {
+    LOG(LOGS_ERR, "Could not open NTS-KE socket on %s", UTI_IPSockAddrToString(&local_addr));
+    return INVALID_SOCK_FD;
+  }
+
+  /* Set the maximum number of waiting connections on the socket to the maximum
+     number of concurrent sessions */
+  backlog = MAX(CNF_GetNtsServerProcesses(), 1) * CNF_GetNtsServerConnections();
+
+  if (!SCK_ListenOnSocket(sock_fd, backlog)) {
+    SCK_CloseSocket(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, accept_connection, NULL);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static void
+helper_signal(int x)
+{
+  SCH_QuitProgram();
+}
+
+/* ================================================== */
+
+static int
+prepare_response(NKSN_Instance session, int error, int next_protocol, int aead_algorithm)
+{
+  NKE_Context context;
+  NKE_Cookie cookie;
+  char *ntp_server;
+  uint16_t datum;
+  int i;
+
+  DEBUG_LOG("NTS KE response: error=%d next=%d aead=%d", error, next_protocol, aead_algorithm);
+
+  NKSN_BeginMessage(session);
+
+  if (error >= 0) {
+    datum = htons(error);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_ERROR, &datum, sizeof (datum)))
+      return 0;
+  } else if (next_protocol < 0) {
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, NULL, 0))
+      return 0;
+  } else if (aead_algorithm < 0) {
+    datum = htons(next_protocol);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+      return 0;
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, NULL, 0))
+      return 0;
+  } else {
+    datum = htons(next_protocol);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+      return 0;
+
+    datum = htons(aead_algorithm);
+    if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, &datum, sizeof (datum)))
+      return 0;
+
+    if (CNF_GetNTPPort() != NTP_PORT) {
+      datum = htons(CNF_GetNTPPort());
+      if (!NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_PORT_NEGOTIATION, &datum, sizeof (datum)))
+        return 0;
+    }
+
+    ntp_server = CNF_GetNtsNtpServer();
+    if (ntp_server) {
+      if (!NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                          ntp_server, strlen(ntp_server)))
+        return 0;
+    }
+
+    context.algorithm = aead_algorithm;
+
+    if (!NKSN_GetKeys(session, aead_algorithm, &context.c2s, &context.s2c))
+      return 0;
+
+    for (i = 0; i < NKE_MAX_COOKIES; i++) {
+      if (!NKS_GenerateCookie(&context, &cookie))
+        return 0;
+      if (!NKSN_AddRecord(session, 0, NKE_RECORD_COOKIE, cookie.cookie, cookie.length))
+        return 0;
+    }
+  }
+
+  if (!NKSN_EndMessage(session))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+process_request(NKSN_Instance session)
+{
+  int next_protocol_records = 0, aead_algorithm_records = 0;
+  int next_protocol_values = 0, aead_algorithm_values = 0;
+  int next_protocol = -1, aead_algorithm = -1, error = -1;
+  int i, critical, type, length;
+  uint16_t data[NKE_MAX_RECORD_BODY_LENGTH / sizeof (uint16_t)];
+
+  assert(NKE_MAX_RECORD_BODY_LENGTH % sizeof (uint16_t) == 0);
+  assert(sizeof (uint16_t) == 2);
+
+  while (error < 0) {
+    if (!NKSN_GetRecord(session, &critical, &type, &length, &data, sizeof (data)))
+      break;
+
+    switch (type) {
+      case NKE_RECORD_NEXT_PROTOCOL:
+        if (!critical || length < 2 || length % 2 != 0) {
+          error = NKE_ERROR_BAD_REQUEST;
+          break;
+        }
+
+        next_protocol_records++;
+
+        for (i = 0; i < MIN(length, sizeof (data)) / 2; i++) {
+          next_protocol_values++;
+          if (ntohs(data[i]) == NKE_NEXT_PROTOCOL_NTPV4)
+            next_protocol = NKE_NEXT_PROTOCOL_NTPV4;
+        }
+        break;
+      case NKE_RECORD_AEAD_ALGORITHM:
+        if (length < 2 || length % 2 != 0) {
+          error = NKE_ERROR_BAD_REQUEST;
+          break;
+        }
+
+        aead_algorithm_records++;
+
+        for (i = 0; i < MIN(length, sizeof (data)) / 2; i++) {
+          aead_algorithm_values++;
+          /* Use the first supported algorithm */
+          if (aead_algorithm < 0 && SIV_GetKeyLength(ntohs(data[i])) > 0)
+            aead_algorithm = ntohs(data[i]);
+        }
+        break;
+      case NKE_RECORD_ERROR:
+      case NKE_RECORD_WARNING:
+      case NKE_RECORD_COOKIE:
+        error = NKE_ERROR_BAD_REQUEST;
+        break;
+      default:
+        if (critical)
+          error = NKE_ERROR_UNRECOGNIZED_CRITICAL_RECORD;
+    }
+  }
+
+  if (error < 0) {
+    if (next_protocol_records != 1 || next_protocol_values < 1 ||
+        (next_protocol == NKE_NEXT_PROTOCOL_NTPV4 &&
+         (aead_algorithm_records != 1 || aead_algorithm_values < 1)))
+      error = NKE_ERROR_BAD_REQUEST;
+  }
+
+  if (!prepare_response(session, error, next_protocol, aead_algorithm))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+handle_message(void *arg)
+{
+  NKSN_Instance session = arg;
+
+  return process_request(session);
+}
+
+/* ================================================== */
+
+static void
+generate_key(int index)
+{
+  SIV_Algorithm algorithm;
+  ServerKey *key;
+  int key_length;
+
+  if (index < 0 || index >= MAX_SERVER_KEYS)
+    assert(0);
+
+  /* Prefer AES-128-GCM-SIV if available.  Note that if older keys loaded
+     from ntsdumpdir use a different algorithm, responding to NTP requests
+     with cookies encrypted with those keys will not work if the new algorithm
+     produces longer cookies (i.e. response would be longer than request).
+     Switching from AES-SIV-CMAC-256 to AES-128-GCM-SIV is ok. */
+  algorithm = SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0 ?
+              AEAD_AES_128_GCM_SIV : AEAD_AES_SIV_CMAC_256;
+
+  key = &server_keys[index];
+
+  key_length = SIV_GetKeyLength(algorithm);
+  if (key_length > sizeof (key->key))
+    assert(0);
+
+  UTI_GetRandomBytesUrandom(key->key, key_length);
+  memset(key->key + key_length, 0, sizeof (key->key) - key_length);
+  UTI_GetRandomBytes(&key->id, sizeof (key->id));
+
+  /* Encode the index in the lowest bits of the ID */
+  key->id &= -1U << KEY_ID_INDEX_BITS;
+  key->id |= index;
+
+  update_key_siv(key, algorithm);
+
+  DEBUG_LOG("Generated key %08"PRIX32" (%d)", key->id, (int)key->siv_algorithm);
+
+  last_server_key_ts = SCH_GetLastEventMonoTime();
+}
+
+/* ================================================== */
+
+static void
+save_keys(void)
+{
+  char buf[SIV_MAX_KEY_LENGTH * 2 + 1], *dump_dir;
+  int i, index, key_length;
+  double last_key_age;
+  FILE *f;
+
+  /* Don't save the keys if rotation is disabled to enable an external
+     management of the keys (e.g. share them with another server) */
+  if (key_rotation_interval == 0)
+    return;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  f = UTI_OpenFile(dump_dir, DUMP_FILENAME, ".tmp", 'w', 0600);
+  if (!f)
+    return;
+
+  last_key_age = SCH_GetLastEventMonoTime() - last_server_key_ts;
+
+  if (fprintf(f, "%s%.1f\n", DUMP_IDENTIFIER, last_key_age) < 0)
+    goto error;
+
+  for (i = 0; i < MAX_SERVER_KEYS; i++) {
+    index = (current_server_key + i + 1 + FUTURE_KEYS) % MAX_SERVER_KEYS;
+    key_length = SIV_GetKeyLength(server_keys[index].siv_algorithm);
+
+    if (key_length > sizeof (server_keys[index].key) ||
+        !UTI_BytesToHex(server_keys[index].key, key_length, buf, sizeof (buf)) ||
+        fprintf(f, "%08"PRIX32" %s %d\n", server_keys[index].id, buf,
+                (int)server_keys[index].siv_algorithm) < 0)
+      goto error;
+  }
+
+  fclose(f);
+
+  /* Rename the temporary file, or remove it if that fails */
+  if (!UTI_RenameTempFile(dump_dir, DUMP_FILENAME, ".tmp", NULL)) {
+    if (!UTI_RemoveFile(dump_dir, DUMP_FILENAME, ".tmp"))
+      ;
+  }
+
+  return;
+
+error:
+  LOG(LOGS_ERR, "Could not %s %s", "save", "server NTS keys");
+  fclose(f);
+
+  if (!UTI_RemoveFile(dump_dir, DUMP_FILENAME, NULL))
+    ;
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 3
+
+static int
+load_keys(void)
+{
+  int i, index, key_length, algorithm = 0, old_ver;
+  char *dump_dir, line[1024], *words[MAX_WORDS];
+  ServerKey new_keys[MAX_SERVER_KEYS];
+  double key_age;
+  FILE *f;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return 0;
+
+  f = UTI_OpenFile(dump_dir, DUMP_FILENAME, NULL, 'r', 0);
+  if (!f)
+    return 0;
+
+  if (!fgets(line, sizeof (line), f) ||
+      (strcmp(line, DUMP_IDENTIFIER) != 0 && strcmp(line, OLD_DUMP_IDENTIFIER) != 0))
+    goto error;
+
+  old_ver = strcmp(line, DUMP_IDENTIFIER) != 0;
+
+  if (!fgets(line, sizeof (line), f) ||
+      UTI_SplitString(line, words, MAX_WORDS) != (old_ver ? 2 : 1) ||
+      (old_ver && sscanf(words[0], "%d", &algorithm) != 1) ||
+      sscanf(words[old_ver ? 1 : 0], "%lf", &key_age) != 1)
+    goto error;
+
+  for (i = 0; i < MAX_SERVER_KEYS && fgets(line, sizeof (line), f); i++) {
+    if (UTI_SplitString(line, words, MAX_WORDS) != (old_ver ? 2 : 3) ||
+        sscanf(words[0], "%"PRIX32, &new_keys[i].id) != 1 ||
+        (!old_ver && sscanf(words[2], "%d", &algorithm) != 1))
+      goto error;
+
+    new_keys[i].siv_algorithm = algorithm;
+    key_length = SIV_GetKeyLength(algorithm);
+
+    if ((i > 0 && (new_keys[i].id - new_keys[i - 1].id) % MAX_SERVER_KEYS != 1) ||
+        key_length <= 0 ||
+        UTI_HexToBytes(words[1], new_keys[i].key, sizeof (new_keys[i].key)) != key_length)
+      goto error;
+    memset(new_keys[i].key + key_length, 0, sizeof (new_keys[i].key) - key_length);
+  }
+
+  if (i < MAX_SERVER_KEYS)
+    goto error;
+
+  for (i = 0; i < MAX_SERVER_KEYS; i++) {
+    index = new_keys[i].id % MAX_SERVER_KEYS;
+    server_keys[index].id = new_keys[i].id;
+    memcpy(server_keys[index].key, new_keys[i].key, sizeof (server_keys[index].key));
+
+    update_key_siv(&server_keys[index], new_keys[i].siv_algorithm);
+
+    DEBUG_LOG("Loaded key %08"PRIX32" (%d)",
+              server_keys[index].id, (int)server_keys[index].siv_algorithm);
+  }
+
+  current_server_key = (index + MAX_SERVER_KEYS - FUTURE_KEYS) % MAX_SERVER_KEYS;
+  last_server_key_ts = SCH_GetLastEventMonoTime() - MAX(key_age, 0.0);
+
+  fclose(f);
+
+  LOG(LOGS_INFO, "Loaded %s", "server NTS keys");
+  return 1;
+
+error:
+  LOG(LOGS_ERR, "Could not %s %s", "load", "server NTS keys");
+  fclose(f);
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+key_timeout(void *arg)
+{
+  current_server_key = (current_server_key + 1) % MAX_SERVER_KEYS;
+  generate_key((current_server_key + FUTURE_KEYS) % MAX_SERVER_KEYS);
+  save_keys();
+
+  SCH_AddTimeoutByDelay(key_rotation_interval, key_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+run_helper(uid_t uid, gid_t gid, int scfilter_level)
+{
+  LOG_Severity log_severity;
+
+  /* Finish minimal initialisation and run using the scheduler loop
+     similarly to the main process */
+
+  DEBUG_LOG("Helper started");
+
+  /* Suppress a log message about disabled clock control */
+  log_severity = LOG_GetMinSeverity();
+  LOG_SetMinSeverity(LOGS_ERR);
+
+  SYS_Initialise(0);
+  LOG_SetMinSeverity(log_severity);
+
+  if (!geteuid() && (uid || gid))
+    SYS_DropRoot(uid, gid, SYS_NTSKE_HELPER);
+
+  NKS_Initialise();
+
+  UTI_SetQuitSignalsHandler(helper_signal, 1);
+  if (scfilter_level != 0)
+    SYS_EnableSystemCallFilter(scfilter_level, SYS_NTSKE_HELPER);
+
+  SCH_MainLoop();
+
+  DEBUG_LOG("Helper exiting");
+
+  NKS_Finalise();
+  SCK_Finalise();
+  SYS_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+  CNF_Finalise();
+  LOG_Finalise();
+
+  UTI_ResetGetRandomFunctions();
+
+  exit(0);
+}
+
+/* ================================================== */
+
+void
+NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level)
+{
+  int i, processes, sock_fd1, sock_fd2;
+  const char **certs, **keys;
+  char prefix[16];
+  pid_t pid;
+
+  helper_sock_fd = INVALID_SOCK_FD;
+  is_helper = 0;
+
+  if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0)
+    return;
+
+  processes = CNF_GetNtsServerProcesses();
+  if (processes <= 0)
+    return;
+
+  /* Start helper processes to perform (computationally expensive) NTS-KE
+     sessions with clients on sockets forwarded from the main process */
+
+  sock_fd1 = SCK_OpenUnixSocketPair(0, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");
+
+  for (i = 0; i < processes; i++) {
+    pid = fork();
+
+    if (pid < 0)
+      LOG_FATAL("fork() failed : %s", strerror(errno));
+
+    if (pid > 0)
+      continue;
+
+    is_helper = 1;
+
+    UTI_ResetGetRandomFunctions();
+
+    snprintf(prefix, sizeof (prefix), "nks#%d:", i + 1);
+    LOG_SetDebugPrefix(prefix);
+    LOG_CloseParentFd();
+
+    SCK_CloseSocket(sock_fd1);
+    SCH_AddFileHandler(sock_fd2, SCH_FILE_INPUT, handle_helper_request, NULL);
+
+    run_helper(uid, gid, scfilter_level);
+  }
+
+  SCK_CloseSocket(sock_fd2);
+  helper_sock_fd = sock_fd1;
+}
+
+/* ================================================== */
+
+void
+NKS_Initialise(void)
+{
+  const char **certs, **keys;
+  int i, n_certs_keys;
+  double key_delay;
+
+  server_sock_fd4 = INVALID_SOCK_FD;
+  server_sock_fd6 = INVALID_SOCK_FD;
+
+  n_certs_keys = CNF_GetNtsServerCertAndKeyFiles(&certs, &keys);
+  if (n_certs_keys <= 0)
+    return;
+
+  if (helper_sock_fd == INVALID_SOCK_FD) {
+    server_credentials = NKSN_CreateServerCertCredentials(certs, keys, n_certs_keys);
+    if (!server_credentials)
+      return;
+  } else {
+    server_credentials = NULL;
+  }
+
+  sessions = ARR_CreateInstance(sizeof (NKSN_Instance));
+  for (i = 0; i < CNF_GetNtsServerConnections(); i++)
+    *(NKSN_Instance *)ARR_GetNewElement(sessions) = NULL;
+
+  /* Generate random keys, even if they will be replaced by reloaded keys,
+     or unused (in the helper) */
+  for (i = 0; i < MAX_SERVER_KEYS; i++) {
+    server_keys[i].siv = NULL;
+    generate_key(i);
+  }
+
+  current_server_key = MAX_SERVER_KEYS - 1;
+
+  if (!is_helper) {
+    server_sock_fd4 = open_socket(IPADDR_INET4);
+    server_sock_fd6 = open_socket(IPADDR_INET6);
+
+    key_rotation_interval = MAX(CNF_GetNtsRotate(), 0);
+
+    /* Reload saved keys, or save the new keys */
+    if (!load_keys())
+      save_keys();
+
+    if (key_rotation_interval > 0) {
+      key_delay = key_rotation_interval - (SCH_GetLastEventMonoTime() - last_server_key_ts);
+      SCH_AddTimeoutByDelay(MAX(key_delay, 0.0), key_timeout, NULL);
+    }
+
+    /* Warn if keys are not saved, which can cause a flood of requests
+       after server restart */
+    if (!CNF_GetNtsDumpDir())
+      LOG(LOGS_WARN, "No ntsdumpdir to save server keys");
+  }
+
+  initialised = 1;
+}
+
+/* ================================================== */
+
+void
+NKS_Finalise(void)
+{
+  int i;
+
+  if (!initialised)
+    return;
+
+  if (helper_sock_fd != INVALID_SOCK_FD) {
+    /* Send the helpers a request to exit */
+    for (i = 0; i < CNF_GetNtsServerProcesses(); i++) {
+      if (!SCK_Send(helper_sock_fd, "", 1, 0))
+        ;
+    }
+    SCK_CloseSocket(helper_sock_fd);
+  }
+  if (server_sock_fd4 != INVALID_SOCK_FD)
+    SCK_CloseSocket(server_sock_fd4);
+  if (server_sock_fd6 != INVALID_SOCK_FD)
+    SCK_CloseSocket(server_sock_fd6);
+
+  if (!is_helper)
+    save_keys();
+
+  for (i = 0; i < MAX_SERVER_KEYS; i++)
+    SIV_DestroyInstance(server_keys[i].siv);
+
+  for (i = 0; i < ARR_GetSize(sessions); i++) {
+    NKSN_Instance session = *(NKSN_Instance *)ARR_GetElement(sessions, i);
+    if (session)
+      NKSN_DestroyInstance(session);
+  }
+  ARR_DestroyInstance(sessions);
+
+  if (server_credentials)
+    NKSN_DestroyCertCredentials(server_credentials);
+}
+
+/* ================================================== */
+
+void
+NKS_DumpKeys(void)
+{
+  save_keys();
+}
+
+/* ================================================== */
+
+void
+NKS_ReloadKeys(void)
+{
+  /* Don't load the keys if they are expected to be generated by this server
+     instance (i.e. they are already loaded) to not delay the next rotation */
+  if (key_rotation_interval > 0)
+    return;
+
+  load_keys();
+}
+
+/* ================================================== */
+
+/* A server cookie consists of key ID, nonce, and encrypted C2S+S2C keys */
+
+int
+NKS_GenerateCookie(NKE_Context *context, NKE_Cookie *cookie)
+{
+  unsigned char *nonce, plaintext[2 * NKE_MAX_KEY_LENGTH], *ciphertext;
+  int plaintext_length, tag_length;
+  ServerCookieHeader *header;
+  ServerKey *key;
+
+  if (!initialised) {
+    DEBUG_LOG("NTS server disabled");
+    return 0;
+  }
+
+  /* The AEAD ID is not encoded in the cookie.  It is implied from the key
+     length (as long as only algorithms with different key lengths are
+     supported). */
+
+  if (context->c2s.length < 0 || context->c2s.length > NKE_MAX_KEY_LENGTH ||
+      context->s2c.length != context->c2s.length) {
+    DEBUG_LOG("Invalid key length");
+    return 0;
+  }
+
+  key = &server_keys[current_server_key];
+
+  header = (ServerCookieHeader *)cookie->cookie;
+
+  header->key_id = htonl(key->id);
+
+  nonce = cookie->cookie + sizeof (*header);
+  if (key->nonce_length > sizeof (cookie->cookie) - sizeof (*header))
+    assert(0);
+  UTI_GetRandomBytes(nonce, key->nonce_length);
+
+  plaintext_length = context->c2s.length + context->s2c.length;
+  assert(plaintext_length <= sizeof (plaintext));
+  memcpy(plaintext, context->c2s.key, context->c2s.length);
+  memcpy(plaintext + context->c2s.length, context->s2c.key, context->s2c.length);
+
+  tag_length = SIV_GetTagLength(key->siv);
+  cookie->length = sizeof (*header) + key->nonce_length + plaintext_length + tag_length;
+  assert(cookie->length <= sizeof (cookie->cookie));
+  ciphertext = cookie->cookie + sizeof (*header) + key->nonce_length;
+
+  if (!SIV_Encrypt(key->siv, nonce, key->nonce_length,
+                   "", 0,
+                   plaintext, plaintext_length,
+                   ciphertext, plaintext_length + tag_length)) {
+    DEBUG_LOG("Could not encrypt cookie");
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Context *context)
+{
+  unsigned char *nonce, plaintext[2 * NKE_MAX_KEY_LENGTH], *ciphertext;
+  int ciphertext_length, plaintext_length, tag_length;
+  ServerCookieHeader *header;
+  ServerKey *key;
+  uint32_t key_id;
+
+  if (!initialised) {
+    DEBUG_LOG("NTS server disabled");
+    return 0;
+  }
+
+  if (cookie->length <= (int)sizeof (*header)) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  header = (ServerCookieHeader *)cookie->cookie;
+
+  key_id = ntohl(header->key_id);
+  key = &server_keys[key_id % MAX_SERVER_KEYS];
+  if (key_id != key->id) {
+    DEBUG_LOG("Unknown key %"PRIX32, key_id);
+    return 0;
+  }
+
+  tag_length = SIV_GetTagLength(key->siv);
+
+  if (cookie->length <= (int)sizeof (*header) + key->nonce_length + tag_length) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  nonce = cookie->cookie + sizeof (*header);
+  ciphertext = cookie->cookie + sizeof (*header) + key->nonce_length;
+  ciphertext_length = cookie->length - sizeof (*header) - key->nonce_length;
+  plaintext_length = ciphertext_length - tag_length;
+
+  if (plaintext_length > sizeof (plaintext) || plaintext_length % 2 != 0) {
+    DEBUG_LOG("Invalid cookie length");
+    return 0;
+  }
+
+  if (!SIV_Decrypt(key->siv, nonce, key->nonce_length,
+                   "", 0,
+                   ciphertext, ciphertext_length,
+                   plaintext, plaintext_length)) {
+    DEBUG_LOG("Could not decrypt cookie");
+    return 0;
+  }
+
+  /* Select a supported algorithm corresponding to the key length, avoiding
+     potentially slow SIV_GetKeyLength() */
+  switch (plaintext_length / 2) {
+    case 16:
+      context->algorithm = AEAD_AES_128_GCM_SIV;
+      break;
+    case 32:
+      context->algorithm = AEAD_AES_SIV_CMAC_256;
+      break;
+    default:
+      DEBUG_LOG("Unknown key length");
+      return 0;
+  }
+
+  context->c2s.length = plaintext_length / 2;
+  context->s2c.length = plaintext_length / 2;
+  assert(context->c2s.length <= sizeof (context->c2s.key));
+
+  memcpy(context->c2s.key, plaintext, context->c2s.length);
+  memcpy(context->s2c.key, plaintext + context->c2s.length, context->s2c.length);
+
+  return 1;
+}
diff --git a/nts_ke_server.h b/nts_ke_server.h
new file mode 100644
index 0000000..4d8a92a
--- /dev/null
+++ b/nts_ke_server.h
@@ -0,0 +1,49 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE server
+  */
+
+#ifndef GOT_NTS_KE_SERVER_H
+#define GOT_NTS_KE_SERVER_H
+
+#include "nts_ke.h"
+
+/* Init and fini functions */
+extern void NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level);
+extern void NKS_Initialise(void);
+extern void NKS_Finalise(void);
+
+/* Save the current server keys */
+extern void NKS_DumpKeys(void);
+
+/* Reload the keys */
+extern void NKS_ReloadKeys(void);
+
+/* Generate an NTS cookie with a given context */
+extern int NKS_GenerateCookie(NKE_Context *context, NKE_Cookie *cookie);
+
+/* Validate a cookie and decode the context */
+extern int NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Context *context);
+
+#endif
diff --git a/nts_ke_session.c b/nts_ke_session.c
new file mode 100644
index 0000000..2ae1e91
--- /dev/null
+++ b/nts_ke_session.c
@@ -0,0 +1,929 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020-2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS-KE session used by server and client
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ke_session.h"
+
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "siv.h"
+#include "socket.h"
+#include "sched.h"
+#include "util.h"
+
+#include <gnutls/gnutls.h>
+#include <gnutls/x509.h>
+
+#define INVALID_SOCK_FD (-8)
+
+struct RecordHeader {
+  uint16_t type;
+  uint16_t body_length;
+};
+
+struct Message {
+  int length;
+  int sent;
+  int parsed;
+  int complete;
+  unsigned char data[NKE_MAX_MESSAGE_LENGTH];
+};
+
+typedef enum {
+  KE_WAIT_CONNECT,
+  KE_HANDSHAKE,
+  KE_SEND,
+  KE_RECEIVE,
+  KE_SHUTDOWN,
+  KE_STOPPED,
+} KeState;
+
+struct NKSN_Instance_Record {
+  int server;
+  char *server_name;
+  NKSN_MessageHandler handler;
+  void *handler_arg;
+
+  KeState state;
+  int sock_fd;
+  char *label;
+  gnutls_session_t tls_session;
+  SCH_TimeoutID timeout_id;
+  int retry_factor;
+
+  struct Message message;
+  int new_message;
+};
+
+/* ================================================== */
+
+static gnutls_priority_t priority_cache;
+
+static int credentials_counter = 0;
+
+static int clock_updates = 0;
+
+/* ================================================== */
+
+static void
+reset_message(struct Message *message)
+{
+  message->length = 0;
+  message->sent = 0;
+  message->parsed = 0;
+  message->complete = 0;
+}
+
+/* ================================================== */
+
+static int
+add_record(struct Message *message, int critical, int type, const void *body, int body_length)
+{
+  struct RecordHeader header;
+
+  assert(message->length <= sizeof (message->data));
+
+  if (body_length < 0 || body_length > 0xffff || type < 0 || type > 0x7fff ||
+      message->length + sizeof (header) + body_length > sizeof (message->data))
+    return 0;
+
+  header.type = htons(!!critical * NKE_RECORD_CRITICAL_BIT | type);
+  header.body_length = htons(body_length);
+
+  memcpy(&message->data[message->length], &header, sizeof (header));
+  message->length += sizeof (header);
+
+  if (body_length > 0) {
+    memcpy(&message->data[message->length], body, body_length);
+    message->length += body_length;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+reset_message_parsing(struct Message *message)
+{
+  message->parsed = 0;
+}
+
+/* ================================================== */
+
+static int
+get_record(struct Message *message, int *critical, int *type, int *body_length,
+           void *body, int buffer_length)
+{
+  struct RecordHeader header;
+  int blen, rlen;
+
+  if (message->length < message->parsed + sizeof (header) ||
+      buffer_length < 0)
+    return 0;
+
+  memcpy(&header, &message->data[message->parsed], sizeof (header));
+
+  blen = ntohs(header.body_length);
+  rlen = sizeof (header) + blen;
+  assert(blen >= 0 && rlen > 0);
+
+  if (message->length < message->parsed + rlen)
+    return 0;
+
+  if (critical)
+    *critical = !!(ntohs(header.type) & NKE_RECORD_CRITICAL_BIT);
+  if (type)
+    *type = ntohs(header.type) & ~NKE_RECORD_CRITICAL_BIT;
+  if (body)
+    memcpy(body, &message->data[message->parsed + sizeof (header)], MIN(buffer_length, blen));
+  if (body_length)
+    *body_length = blen;
+
+  message->parsed += rlen;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+check_message_format(struct Message *message, int eof)
+{
+  int critical = 0, type = -1, length = -1, ends = 0;
+
+  reset_message_parsing(message);
+  message->complete = 0;
+
+  while (get_record(message, &critical, &type, &length, NULL, 0)) {
+    if (type == NKE_RECORD_END_OF_MESSAGE) {
+      if (!critical || length != 0 || ends > 0)
+        return 0;
+      ends++;
+    }
+  }
+
+  /* If the message cannot be fully parsed, but more data may be coming,
+     consider the format to be ok */
+  if (message->length == 0 || message->parsed < message->length)
+    return !eof;
+
+  if (type != NKE_RECORD_END_OF_MESSAGE)
+    return !eof;
+
+  message->complete = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static gnutls_session_t
+create_tls_session(int server_mode, int sock_fd, const char *server_name,
+                   gnutls_certificate_credentials_t credentials,
+                   gnutls_priority_t priority)
+{
+  unsigned char alpn_name[sizeof (NKE_ALPN_NAME)];
+  gnutls_session_t session;
+  gnutls_datum_t alpn;
+  unsigned int flags;
+  int r;
+
+  r = gnutls_init(&session, GNUTLS_NONBLOCK | GNUTLS_NO_TICKETS |
+                  (server_mode ? GNUTLS_SERVER : GNUTLS_CLIENT));
+  if (r < 0) {
+    LOG(LOGS_ERR, "Could not %s TLS session : %s", "create", gnutls_strerror(r));
+    return NULL;
+  }
+
+  if (!server_mode) {
+    assert(server_name);
+
+    if (!UTI_IsStringIP(server_name)) {
+      r = gnutls_server_name_set(session, GNUTLS_NAME_DNS, server_name, strlen(server_name));
+      if (r < 0)
+        goto error;
+    }
+
+    flags = 0;
+
+    if (clock_updates < CNF_GetNoCertTimeCheck()) {
+      flags |= GNUTLS_VERIFY_DISABLE_TIME_CHECKS | GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS;
+      DEBUG_LOG("Disabled time checks");
+    }
+
+    gnutls_session_set_verify_cert(session, server_name, flags);
+  }
+
+  r = gnutls_priority_set(session, priority);
+  if (r < 0)
+    goto error;
+
+  r = gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, credentials);
+  if (r < 0)
+    goto error;
+
+  memcpy(alpn_name, NKE_ALPN_NAME, sizeof (alpn_name));
+  alpn.data = alpn_name;
+  alpn.size = sizeof (alpn_name) - 1;
+
+  r = gnutls_alpn_set_protocols(session, &alpn, 1, 0);
+  if (r < 0)
+    goto error;
+
+  gnutls_transport_set_int(session, sock_fd);
+
+  return session;
+
+error:
+  LOG(LOGS_ERR, "Could not %s TLS session : %s", "set", gnutls_strerror(r));
+  gnutls_deinit(session);
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+stop_session(NKSN_Instance inst)
+{
+  if (inst->state == KE_STOPPED)
+    return;
+
+  inst->state = KE_STOPPED;
+
+  SCH_RemoveFileHandler(inst->sock_fd);
+  SCK_CloseSocket(inst->sock_fd);
+  inst->sock_fd = INVALID_SOCK_FD;
+
+  Free(inst->label);
+  inst->label = NULL;
+
+  gnutls_deinit(inst->tls_session);
+  inst->tls_session = NULL;
+
+  SCH_RemoveTimeout(inst->timeout_id);
+  inst->timeout_id = 0;
+}
+
+/* ================================================== */
+
+static void
+session_timeout(void *arg)
+{
+  NKSN_Instance inst = arg;
+
+  LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE session with %s timed out", inst->label);
+
+  inst->timeout_id = 0;
+  stop_session(inst);
+}
+
+/* ================================================== */
+
+static int
+check_alpn(NKSN_Instance inst)
+{
+  gnutls_datum_t alpn;
+
+  if (gnutls_alpn_get_selected_protocol(inst->tls_session, &alpn) < 0 ||
+      alpn.size != sizeof (NKE_ALPN_NAME) - 1 ||
+      memcmp(alpn.data, NKE_ALPN_NAME, sizeof (NKE_ALPN_NAME) - 1) != 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_input_output(NKSN_Instance inst, int output)
+{
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_INPUT, !output);
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT, output);
+}
+
+/* ================================================== */
+
+static void
+change_state(NKSN_Instance inst, KeState state)
+{
+  int output;
+
+  switch (state) {
+    case KE_HANDSHAKE:
+      output = !inst->server;
+      break;
+    case KE_WAIT_CONNECT:
+    case KE_SEND:
+    case KE_SHUTDOWN:
+      output = 1;
+      break;
+    case KE_RECEIVE:
+      output = 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  set_input_output(inst, output);
+
+  inst->state = state;
+}
+
+/* ================================================== */
+
+static int
+handle_event(NKSN_Instance inst, int event)
+{
+  struct Message *message = &inst->message;
+  int r;
+
+  DEBUG_LOG("Session event %d fd=%d state=%d", event, inst->sock_fd, (int)inst->state);
+
+  switch (inst->state) {
+    case KE_WAIT_CONNECT:
+      /* Check if connect() succeeded */
+      if (event != SCH_FILE_OUTPUT)
+        return 0;
+
+      /* Get the socket error */
+      if (!SCK_GetIntOption(inst->sock_fd, SOL_SOCKET, SO_ERROR, &r))
+        r = EINVAL;
+
+      if (r != 0) {
+        LOG(LOGS_ERR, "Could not connect to %s : %s", inst->label, strerror(r));
+        stop_session(inst);
+        return 0;
+      }
+
+      DEBUG_LOG("Connected to %s", inst->label);
+
+      change_state(inst, KE_HANDSHAKE);
+      return 0;
+
+    case KE_HANDSHAKE:
+      r = gnutls_handshake(inst->tls_session);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          gnutls_datum_t cert_error;
+
+          /* Get a description of verification errors */
+          if (r != GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR ||
+              gnutls_certificate_verification_status_print(
+                          gnutls_session_get_verify_cert_status(inst->tls_session),
+                          gnutls_certificate_type_get(inst->tls_session), &cert_error, 0) < 0)
+            cert_error.data = NULL;
+
+          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+              "TLS handshake with %s failed : %s%s%s", inst->label, gnutls_strerror(r),
+              cert_error.data ? " " : "", cert_error.data ? (const char *)cert_error.data : "");
+
+          if (cert_error.data)
+            gnutls_free(cert_error.data);
+
+          stop_session(inst);
+
+          /* Increase the retry interval if the handshake did not fail due
+             to the other end closing the connection */
+          if (r != GNUTLS_E_PULL_ERROR && r != GNUTLS_E_PREMATURE_TERMINATION)
+            inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
+          return 0;
+        }
+
+        /* Disable output when the handshake is trying to receive data */
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
+        return 0;
+      }
+
+      inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
+      if (DEBUG) {
+        char *description = gnutls_session_get_desc(inst->tls_session);
+        DEBUG_LOG("Handshake with %s completed %s",
+                  inst->label, description ? description : "");
+        gnutls_free(description);
+      }
+
+      if (!check_alpn(inst)) {
+        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE not supported by %s", inst->label);
+        stop_session(inst);
+        return 0;
+      }
+
+      /* Client will send a request to the server */
+      change_state(inst, inst->server ? KE_RECEIVE : KE_SEND);
+      return 0;
+
+    case KE_SEND:
+      assert(inst->new_message && message->complete);
+      assert(message->length <= sizeof (message->data) && message->length > message->sent);
+
+      r = gnutls_record_send(inst->tls_session, &message->data[message->sent],
+                             message->length - message->sent);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+              "Could not send NTS-KE message to %s : %s", inst->label, gnutls_strerror(r));
+          stop_session(inst);
+        }
+        return 0;
+      }
+
+      DEBUG_LOG("Sent %d bytes to %s", r, inst->label);
+
+      message->sent += r;
+      if (message->sent < message->length)
+        return 0;
+
+      /* Client will receive a response */
+      change_state(inst, inst->server ? KE_SHUTDOWN : KE_RECEIVE);
+      reset_message(&inst->message);
+      inst->new_message = 0;
+      return 0;
+
+    case KE_RECEIVE:
+      do {
+        if (message->length >= sizeof (message->data)) {
+          DEBUG_LOG("Message is too long");
+          stop_session(inst);
+          return 0;
+        }
+
+        r = gnutls_record_recv(inst->tls_session, &message->data[message->length],
+                               sizeof (message->data) - message->length);
+
+        if (r < 0) {
+          /* Handle a renegotiation request on both client and server as
+             a protocol error */
+          if (gnutls_error_is_fatal(r) || r == GNUTLS_E_REHANDSHAKE) {
+            LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+                "Could not receive NTS-KE message from %s : %s",
+                inst->label, gnutls_strerror(r));
+            stop_session(inst);
+          }
+          return 0;
+        }
+
+        DEBUG_LOG("Received %d bytes from %s", r, inst->label);
+
+        message->length += r;
+
+      } while (gnutls_record_check_pending(inst->tls_session) > 0);
+
+      if (!check_message_format(message, r == 0)) {
+        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
+            "Received invalid NTS-KE message from %s", inst->label);
+        stop_session(inst);
+        return 0;
+      }
+
+      /* Wait for more data if the message is not complete yet */
+      if (!message->complete)
+        return 0;
+
+      /* Server will send a response to the client */
+      change_state(inst, inst->server ? KE_SEND : KE_SHUTDOWN);
+
+      /* Return success to process the received message */
+      return 1;
+
+    case KE_SHUTDOWN:
+      r = gnutls_bye(inst->tls_session, GNUTLS_SHUT_RDWR);
+
+      if (r < 0) {
+        if (gnutls_error_is_fatal(r)) {
+          DEBUG_LOG("Shutdown with %s failed : %s", inst->label, gnutls_strerror(r));
+          stop_session(inst);
+          return 0;
+        }
+
+        /* Disable output when the TLS shutdown is trying to receive data */
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
+        return 0;
+      }
+
+      SCK_ShutdownConnection(inst->sock_fd);
+      stop_session(inst);
+
+      DEBUG_LOG("Shutdown completed");
+      return 0;
+
+    default:
+      assert(0);
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+static void
+read_write_socket(int fd, int event, void *arg)
+{
+  NKSN_Instance inst = arg;
+
+  if (!handle_event(inst, event))
+    return;
+
+  /* A valid message was received.  Call the handler to process the message,
+     and prepare a response if it is a server. */
+
+  reset_message_parsing(&inst->message);
+
+  if (!(inst->handler)(inst->handler_arg)) {
+    stop_session(inst);
+    return;
+  }
+}
+
+/* ================================================== */
+
+static time_t
+get_time(time_t *t)
+{
+  struct timespec now;
+
+  LCL_ReadCookedTime(&now, NULL);
+  if (t)
+    *t = now.tv_sec;
+
+  return now.tv_sec;
+}
+
+/* ================================================== */
+
+static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type != LCL_ChangeUnknownStep && clock_updates < INT_MAX)
+    clock_updates++;
+}
+
+/* ================================================== */
+
+static int gnutls_initialised = 0;
+
+static int
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return 1;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  /* Prepare a priority cache for server and client NTS-KE sessions
+     (the NTS specification requires TLS1.3 or later) */
+  r = gnutls_priority_init2(&priority_cache,
+                            "-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-TLS1.2:-VERS-DTLS-ALL",
+                            NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND);
+  if (r < 0) {
+    LOG(LOGS_ERR, "Could not initialise %s : %s",
+        "priority cache for TLS", gnutls_strerror(r));
+    gnutls_global_deinit();
+    return 0;
+  }
+
+  /* Use our clock instead of the system clock in certificate verification */
+  gnutls_global_set_time_function(get_time);
+
+  gnutls_initialised = 1;
+  DEBUG_LOG("Initialised");
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  if (!gnutls_initialised || credentials_counter > 0)
+    return;
+
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);
+
+  gnutls_priority_deinit(priority_cache);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static NKSN_Credentials
+create_credentials(const char **certs, const char **keys, int n_certs_keys,
+                   const char **trusted_certs, uint32_t *trusted_certs_ids,
+                   int n_trusted_certs, uint32_t trusted_cert_set)
+{
+  gnutls_certificate_credentials_t credentials = NULL;
+  int i, r;
+
+  if (!init_gnutls())
+    return NULL;
+
+  r = gnutls_certificate_allocate_credentials(&credentials);
+  if (r < 0)
+    goto error;
+
+  if (certs && keys) {
+    if (trusted_certs || trusted_certs_ids)
+      assert(0);
+
+    for (i = 0; i < n_certs_keys; i++) {
+      if (!UTI_CheckFilePermissions(keys[i], 0771))
+        ;
+      r = gnutls_certificate_set_x509_key_file(credentials, certs[i], keys[i],
+                                               GNUTLS_X509_FMT_PEM);
+      if (r < 0)
+        goto error;
+    }
+  } else {
+    if (certs || keys || n_certs_keys > 0)
+      assert(0);
+
+    if (trusted_cert_set == 0 && !CNF_GetNoSystemCert()) {
+      r = gnutls_certificate_set_x509_system_trust(credentials);
+      if (r < 0)
+        goto error;
+    }
+
+    if (trusted_certs && trusted_certs_ids) {
+      for (i = 0; i < n_trusted_certs; i++) {
+        struct stat buf;
+
+        if (trusted_certs_ids[i] != trusted_cert_set)
+          continue;
+
+        if (stat(trusted_certs[i], &buf) == 0 && S_ISDIR(buf.st_mode))
+          r = gnutls_certificate_set_x509_trust_dir(credentials, trusted_certs[i],
+                                                    GNUTLS_X509_FMT_PEM);
+        else
+          r = gnutls_certificate_set_x509_trust_file(credentials, trusted_certs[i],
+                                                     GNUTLS_X509_FMT_PEM);
+        if (r < 0)
+          goto error;
+
+        DEBUG_LOG("Added %d trusted certs from %s", r, trusted_certs[i]);
+      }
+    }
+  }
+
+  credentials_counter++;
+
+  return (NKSN_Credentials)credentials;
+
+error:
+  LOG(LOGS_ERR, "Could not set credentials : %s", gnutls_strerror(r));
+  if (credentials)
+    gnutls_certificate_free_credentials(credentials);
+  deinit_gnutls();
+  return NULL;
+}
+
+/* ================================================== */
+
+NKSN_Credentials
+NKSN_CreateServerCertCredentials(const char **certs, const char **keys, int n_certs_keys)
+{
+  return create_credentials(certs, keys, n_certs_keys, NULL, NULL, 0, 0);
+}
+
+/* ================================================== */
+
+NKSN_Credentials
+NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                 int n_certs_ids, uint32_t trusted_cert_set)
+{
+  return create_credentials(NULL, NULL, 0, certs, ids, n_certs_ids, trusted_cert_set);
+}
+
+/* ================================================== */
+
+void
+NKSN_DestroyCertCredentials(NKSN_Credentials credentials)
+{
+  gnutls_certificate_free_credentials((gnutls_certificate_credentials_t)credentials);
+  credentials_counter--;
+  deinit_gnutls();
+}
+
+/* ================================================== */
+
+NKSN_Instance
+NKSN_CreateInstance(int server_mode, const char *server_name,
+                    NKSN_MessageHandler handler, void *handler_arg)
+{
+  NKSN_Instance inst;
+
+  inst = MallocNew(struct NKSN_Instance_Record);
+
+  inst->server = server_mode;
+  inst->server_name = server_name ? Strdup(server_name) : NULL;
+  inst->handler = handler;
+  inst->handler_arg = handler_arg;
+  /* Replace a NULL argument with the session itself */
+  if (!inst->handler_arg)
+    inst->handler_arg = inst;
+
+  inst->state = KE_STOPPED;
+  inst->sock_fd = INVALID_SOCK_FD;
+  inst->label = NULL;
+  inst->tls_session = NULL;
+  inst->timeout_id = 0;
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NKSN_DestroyInstance(NKSN_Instance inst)
+{
+  stop_session(inst);
+
+  Free(inst->server_name);
+  Free(inst);
+}
+
+/* ================================================== */
+
+int
+NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                  NKSN_Credentials credentials, double timeout)
+{
+  assert(inst->state == KE_STOPPED);
+
+  inst->tls_session = create_tls_session(inst->server, sock_fd, inst->server_name,
+                                         (gnutls_certificate_credentials_t)credentials,
+                                         priority_cache);
+  if (!inst->tls_session)
+    return 0;
+
+  inst->sock_fd = sock_fd;
+  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_write_socket, inst);
+
+  inst->label = Strdup(label);
+  inst->timeout_id = SCH_AddTimeoutByDelay(timeout, session_timeout, inst);
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;
+
+  reset_message(&inst->message);
+  inst->new_message = 0;
+
+  change_state(inst, inst->server ? KE_HANDSHAKE : KE_WAIT_CONNECT);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NKSN_BeginMessage(NKSN_Instance inst)
+{
+  reset_message(&inst->message);
+  inst->new_message = 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_AddRecord(NKSN_Instance inst, int critical, int type, const void *body, int body_length)
+{
+  assert(inst->new_message && !inst->message.complete);
+  assert(type != NKE_RECORD_END_OF_MESSAGE);
+
+  return add_record(&inst->message, critical, type, body, body_length);
+}
+
+/* ================================================== */
+
+int
+NKSN_EndMessage(NKSN_Instance inst)
+{
+  assert(!inst->message.complete);
+
+  /* Terminate the message */
+  if (!add_record(&inst->message, 1, NKE_RECORD_END_OF_MESSAGE, NULL, 0))
+    return 0;
+
+  inst->message.complete = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
+               void *body, int buffer_length)
+{
+  int type2;
+
+  assert(inst->message.complete);
+
+  if (body_length)
+    *body_length = 0;
+
+  if (!get_record(&inst->message, critical, &type2, body_length, body, buffer_length))
+    return 0;
+
+  /* Hide the end-of-message record */
+  if (type2 == NKE_RECORD_END_OF_MESSAGE)
+    return 0;
+
+  if (type)
+    *type = type2;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c)
+{
+  int length = SIV_GetKeyLength(siv);
+
+  if (length <= 0 || length > sizeof (c2s->key) || length > sizeof (s2c->key)) {
+    DEBUG_LOG("Invalid algorithm");
+    return 0;
+  }
+
+  if (gnutls_prf_rfc5705(inst->tls_session,
+                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
+                         sizeof (NKE_EXPORTER_CONTEXT_C2S) - 1, NKE_EXPORTER_CONTEXT_C2S,
+                         length, (char *)c2s->key) < 0 ||
+      gnutls_prf_rfc5705(inst->tls_session,
+                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
+                         sizeof (NKE_EXPORTER_CONTEXT_S2C) - 1, NKE_EXPORTER_CONTEXT_S2C,
+                         length, (char *)s2c->key) < 0) {
+    DEBUG_LOG("Could not export key");
+    return 0;
+  }
+
+  c2s->length = length;
+  s2c->length = length;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKSN_IsStopped(NKSN_Instance inst)
+{
+  return inst->state == KE_STOPPED;
+}
+
+/* ================================================== */
+
+void
+NKSN_StopSession(NKSN_Instance inst)
+{
+  stop_session(inst);
+}
+
+/* ================================================== */
+
+int
+NKSN_GetRetryFactor(NKSN_Instance inst)
+{
+  return inst->retry_factor;
+}
diff --git a/nts_ke_session.h b/nts_ke_session.h
new file mode 100644
index 0000000..2735e04
--- /dev/null
+++ b/nts_ke_session.h
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-KE session
+  */
+
+#ifndef GOT_NTS_KE_SESSION_H
+#define GOT_NTS_KE_SESSION_H
+
+#include "nts_ke.h"
+#include "siv.h"
+
+typedef struct NKSN_Credentials_Record *NKSN_Credentials;
+
+typedef struct NKSN_Instance_Record *NKSN_Instance;
+
+/* Handler for received NTS-KE messages.  A zero return code stops
+   the session. */
+typedef int (*NKSN_MessageHandler)(void *arg);
+
+/* Get server or client credentials using a server certificate and key,
+   or certificates of trusted CAs.  The credentials may be shared between
+   different clients or servers. */
+extern NKSN_Credentials NKSN_CreateServerCertCredentials(const char **certs, const char **keys,
+                                                         int n_certs_keys);
+extern NKSN_Credentials NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                                         int n_certs_ids,
+                                                         uint32_t trusted_cert_set);
+
+/* Destroy the credentials */
+extern void NKSN_DestroyCertCredentials(NKSN_Credentials credentials);
+
+/* Create an instance */
+extern NKSN_Instance NKSN_CreateInstance(int server_mode, const char *server_name,
+                                         NKSN_MessageHandler handler, void *handler_arg);
+
+/* Destroy an instance */
+extern void NKSN_DestroyInstance(NKSN_Instance inst);
+
+/* Start a new NTS-KE session */
+extern int NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                             NKSN_Credentials credentials, double timeout);
+
+/* Begin an NTS-KE message.  A request should be made right after starting
+   the session and response should be made in the message handler. */
+extern void NKSN_BeginMessage(NKSN_Instance inst);
+
+/* Add a record to the message */
+extern int NKSN_AddRecord(NKSN_Instance inst, int critical, int type,
+                          const void *body, int body_length);
+
+/* Terminate the message */
+extern int NKSN_EndMessage(NKSN_Instance inst);
+
+/* Get the next record from the received message.  This function should be
+   called from the message handler. */
+extern int NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
+                          void *body, int buffer_length);
+
+/* Export NTS keys for a specified algorithm */
+extern int NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c);
+
+/* Check if the session has stopped */
+extern int NKSN_IsStopped(NKSN_Instance inst);
+
+/* Stop the session */
+extern void NKSN_StopSession(NKSN_Instance inst);
+
+/* Get a factor to calculate retry interval (in log2 seconds)
+   based on the session state or how it was terminated */
+extern int NKSN_GetRetryFactor(NKSN_Instance inst);
+
+#endif
diff --git a/nts_ntp.h b/nts_ntp.h
new file mode 100644
index 0000000..e39def2
--- /dev/null
+++ b/nts_ntp.h
@@ -0,0 +1,36 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for the NTS-NTP protocol
+  */
+
+#ifndef GOT_NTS_NTP_H
+#define GOT_NTS_NTP_H
+
+#define NTP_KOD_NTS_NAK                 0x4e54534e
+
+#define NTS_MIN_UNIQ_ID_LENGTH          32
+#define NTS_MIN_UNPADDED_NONCE_LENGTH   16
+#define NTS_MAX_COOKIES                 8
+
+#endif
diff --git a/nts_ntp_auth.c b/nts_ntp_auth.c
new file mode 100644
index 0000000..b92c406
--- /dev/null
+++ b/nts_ntp_auth.c
@@ -0,0 +1,187 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  NTS Authenticator and Encrypted Extension Fields extension field
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_auth.h"
+
+#include "logging.h"
+#include "ntp_ext.h"
+#include "nts_ntp.h"
+#include "siv.h"
+#include "util.h"
+
+struct AuthHeader {
+  uint16_t nonce_length;
+  uint16_t ciphertext_length;
+};
+
+/* ================================================== */
+
+static int
+get_padding_length(int length)
+{
+  return length % 4U ? 4 - length % 4U : 0;
+}
+
+/* ================================================== */
+
+static int
+get_padded_length(int length)
+{
+  return length + get_padding_length(length);
+}
+
+/* ================================================== */
+
+int
+NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                   const unsigned char *nonce, int max_nonce_length,
+                   const unsigned char *plaintext, int plaintext_length,
+                   int min_ef_length)
+{
+  int auth_length, ciphertext_length, assoc_length, nonce_length, max_siv_nonce_length;
+  int nonce_padding, ciphertext_padding, additional_padding;
+  unsigned char *ciphertext, *body;
+  struct AuthHeader *header;
+
+  assert(sizeof (*header) == 4);
+
+  if (max_nonce_length <= 0 || plaintext_length < 0) {
+    DEBUG_LOG("Invalid nonce/plaintext length");
+    return 0;
+  }
+
+  assoc_length = info->length;
+  max_siv_nonce_length = SIV_GetMaxNonceLength(siv);
+  nonce_length = MIN(max_nonce_length, max_siv_nonce_length);
+  ciphertext_length = SIV_GetTagLength(siv) + plaintext_length;
+  nonce_padding = get_padding_length(nonce_length);
+  ciphertext_padding = get_padding_length(ciphertext_length);
+  min_ef_length = get_padded_length(min_ef_length);
+
+  auth_length = sizeof (*header) + nonce_length + nonce_padding +
+                ciphertext_length + ciphertext_padding;
+  additional_padding = MAX(min_ef_length - auth_length - 4, 0);
+  additional_padding = MAX(MIN(NTS_MIN_UNPADDED_NONCE_LENGTH, max_siv_nonce_length) -
+                           nonce_length - nonce_padding, additional_padding);
+  auth_length += additional_padding;
+
+  if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, auth_length,
+                         (void **)&header)) {
+    DEBUG_LOG("Could not add EF");
+    return 0;
+  }
+
+  header->nonce_length = htons(nonce_length);
+  header->ciphertext_length = htons(ciphertext_length);
+
+  body = (unsigned char *)(header + 1);
+  ciphertext = body + nonce_length + nonce_padding;
+
+  if ((unsigned char *)header + auth_length !=
+      ciphertext + ciphertext_length + ciphertext_padding + additional_padding)
+    assert(0);
+
+  memcpy(body, nonce, nonce_length);
+  memset(body + nonce_length, 0, nonce_padding);
+
+  if (!SIV_Encrypt(siv, nonce, nonce_length, packet, assoc_length,
+                   plaintext, plaintext_length, ciphertext, ciphertext_length)) {
+    DEBUG_LOG("SIV encrypt failed");
+    info->length = assoc_length;
+    info->ext_fields--;
+    return 0;
+  }
+
+  memset(ciphertext + ciphertext_length, 0, ciphertext_padding + additional_padding);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv, int ef_start,
+                  unsigned char *plaintext, int buffer_length, int *plaintext_length)
+{
+  int siv_tag_length, max_siv_nonce_length, nonce_length, ciphertext_length;
+  unsigned char *nonce, *ciphertext;
+  int ef_type, ef_body_length;
+  void *ef_body;
+  struct AuthHeader *header;
+
+  if (buffer_length < 0)
+    return 0;
+
+  if (!NEF_ParseField(packet, info->length, ef_start,
+                      NULL, &ef_type, &ef_body, &ef_body_length))
+    return 0;
+
+  if (ef_type != NTP_EF_NTS_AUTH_AND_EEF || ef_body_length < sizeof (*header))
+    return 0;
+
+  header = ef_body;
+
+  nonce_length = ntohs(header->nonce_length);
+  ciphertext_length = ntohs(header->ciphertext_length);
+
+  if (get_padded_length(nonce_length) +
+      get_padded_length(ciphertext_length) > ef_body_length)
+    return 0;
+
+  nonce = (unsigned char *)(header + 1);
+  ciphertext = nonce + get_padded_length(nonce_length);
+
+  max_siv_nonce_length = SIV_GetMaxNonceLength(siv);
+  siv_tag_length = SIV_GetTagLength(siv);
+
+  if (nonce_length < 1 ||
+      ciphertext_length < siv_tag_length ||
+      ciphertext_length - siv_tag_length > buffer_length) {
+    DEBUG_LOG("Unexpected nonce/ciphertext length");
+    return 0;
+  }
+
+  if (sizeof (*header) + MIN(NTS_MIN_UNPADDED_NONCE_LENGTH, max_siv_nonce_length) +
+      get_padded_length(ciphertext_length) > ef_body_length) {
+    DEBUG_LOG("Missing padding");
+    return 0;
+  }
+
+  *plaintext_length = ciphertext_length - siv_tag_length;
+  assert(*plaintext_length >= 0);
+
+  if (!SIV_Decrypt(siv, nonce, nonce_length, packet, ef_start,
+                   ciphertext, ciphertext_length, plaintext, *plaintext_length)) {
+    DEBUG_LOG("SIV decrypt failed");
+    return 0;
+  }
+
+  return 1;
+}
diff --git a/nts_ntp_auth.h b/nts_ntp_auth.h
new file mode 100644
index 0000000..19d04bf
--- /dev/null
+++ b/nts_ntp_auth.h
@@ -0,0 +1,43 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for NTS Authenticator and Encrypted Extension Fields
+  extension field
+  */
+
+#ifndef GOT_NTS_NTP_AUTH_H
+#define GOT_NTS_NTP_AUTH_H
+
+#include "ntp.h"
+#include "siv.h"
+
+extern int NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                              const unsigned char *nonce, int max_nonce_length,
+                              const unsigned char *plaintext, int plaintext_length,
+                              int min_ef_length);
+
+extern int NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
+                             int ef_start, unsigned char *plaintext, int buffer_length,
+                             int *plaintext_length);
+
+#endif
diff --git a/nts_ntp_client.c b/nts_ntp_client.c
new file mode 100644
index 0000000..2f4b728
--- /dev/null
+++ b/nts_ntp_client.c
@@ -0,0 +1,717 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Client NTS-NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_client.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp.h"
+#include "ntp_ext.h"
+#include "ntp_sources.h"
+#include "nts_ke_client.h"
+#include "nts_ntp.h"
+#include "nts_ntp_auth.h"
+#include "sched.h"
+#include "siv.h"
+#include "util.h"
+
+/* Maximum length of all cookies to avoid IP fragmentation */
+#define MAX_TOTAL_COOKIE_LENGTH (8 * 108)
+
+/* Retry interval for NTS-KE start (which doesn't generate network traffic) */
+#define RETRY_INTERVAL_KE_START 2.0
+
+/* Magic string of files containing keys and cookies */
+#define DUMP_IDENTIFIER "NNC0\n"
+
+struct NNC_Instance_Record {
+  /* Address of NTS-KE server */
+  IPSockAddr nts_address;
+  /* Hostname or IP address for certificate verification */
+  char *name;
+  /* ID of trusted certificates */
+  uint32_t cert_set;
+  /* Configured NTP port */
+  uint16_t default_ntp_port;
+  /* Address of NTP server (can be negotiated in NTS-KE) */
+  IPSockAddr ntp_address;
+
+  NKC_Instance nke;
+  SIV_Instance siv;
+
+  int nke_attempts;
+  double next_nke_attempt;
+  double last_nke_success;
+
+  NKE_Context context;
+  unsigned int context_id;
+  NKE_Cookie cookies[NTS_MAX_COOKIES];
+  int num_cookies;
+  int cookie_index;
+  int auth_ready;
+  int nak_response;
+  int ok_response;
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  unsigned char uniq_id[NTS_MIN_UNIQ_ID_LENGTH];
+};
+
+/* ================================================== */
+
+static void save_cookies(NNC_Instance inst);
+static void load_cookies(NNC_Instance inst);
+
+/* ================================================== */
+
+static void
+reset_instance(NNC_Instance inst)
+{
+  if (inst->nke)
+    NKC_DestroyInstance(inst->nke);
+  inst->nke = NULL;
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;
+  inst->last_nke_success = 0.0;
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->context_id = 0;
+  memset(inst->cookies, 0, sizeof (inst->cookies));
+  inst->num_cookies = 0;
+  inst->cookie_index = 0;
+  inst->auth_ready = 0;
+  inst->nak_response = 0;
+  inst->ok_response = 1;
+  memset(inst->nonce, 0, sizeof (inst->nonce));
+  memset(inst->uniq_id, 0, sizeof (inst->uniq_id));
+}
+
+/* ================================================== */
+
+NNC_Instance
+NNC_CreateInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set, uint16_t ntp_port)
+{
+  NNC_Instance inst;
+
+  inst = MallocNew(struct NNC_Instance_Record);
+
+  inst->nts_address = *nts_address;
+  inst->name = Strdup(name);
+  inst->cert_set = cert_set;
+  inst->default_ntp_port = ntp_port;
+  inst->ntp_address.ip_addr = nts_address->ip_addr;
+  inst->ntp_address.port = ntp_port;
+  inst->siv = NULL;
+  inst->nke = NULL;
+
+  reset_instance(inst);
+
+  /* Try to reload saved keys and cookies */
+  load_cookies(inst);
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+NNC_DestroyInstance(NNC_Instance inst)
+{
+  save_cookies(inst);
+
+  reset_instance(inst);
+
+  Free(inst->name);
+  Free(inst);
+}
+
+/* ================================================== */
+
+static int
+check_cookies(NNC_Instance inst)
+{
+  /* Force a new NTS-KE session if a NAK was received without a valid response,
+     or the keys encrypting the cookies need to be refreshed */
+  if (inst->num_cookies > 0 &&
+      ((inst->nak_response && !inst->ok_response) ||
+       SCH_GetLastEventMonoTime() - inst->last_nke_success > CNF_GetNtsRefresh())) {
+    inst->num_cookies = 0;
+    DEBUG_LOG("Dropped cookies");
+  }
+
+  return inst->num_cookies > 0;
+}
+
+/* ================================================== */
+
+static int
+set_ntp_address(NNC_Instance inst, NTP_Remote_Address *negotiated_address)
+{
+  NTP_Remote_Address old_address, new_address;
+
+  old_address = inst->ntp_address;
+  new_address = *negotiated_address;
+
+  if (new_address.ip_addr.family == IPADDR_UNSPEC)
+    new_address.ip_addr = inst->nts_address.ip_addr;
+  if (new_address.port == 0)
+    new_address.port = inst->default_ntp_port;
+
+  if (UTI_CompareIPs(&old_address.ip_addr, &new_address.ip_addr, NULL) == 0 &&
+      old_address.port == new_address.port)
+    /* Nothing to do */
+    return 1;
+
+  if (NSR_UpdateSourceNtpAddress(&old_address, &new_address) != NSR_Success) {
+    LOG(LOGS_ERR, "Could not change %s to negotiated address %s",
+        UTI_IPToString(&old_address.ip_addr), UTI_IPToString(&new_address.ip_addr));
+    return 0;
+  }
+
+  inst->ntp_address = new_address;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+update_next_nke_attempt(NNC_Instance inst, int failed_start, double now)
+{
+  int factor, interval;
+
+  if (failed_start) {
+    inst->next_nke_attempt = now + RETRY_INTERVAL_KE_START;
+    return;
+  }
+
+  if (!inst->nke)
+    return;
+
+  factor = NKC_GetRetryFactor(inst->nke);
+  interval = MIN(factor + inst->nke_attempts - 1, NKE_MAX_RETRY_INTERVAL2);
+  inst->next_nke_attempt = now + UTI_Log2ToDouble(interval);
+}
+
+/* ================================================== */
+
+static int
+get_cookies(NNC_Instance inst)
+{
+  NTP_Remote_Address ntp_address;
+  int got_data, failed_start = 0;
+  double now;
+
+  assert(inst->num_cookies == 0);
+
+  now = SCH_GetLastEventMonoTime();
+
+  /* Create and start a new NTS-KE session if not already present */
+  if (!inst->nke) {
+    if (now < inst->next_nke_attempt) {
+      DEBUG_LOG("Limiting NTS-KE request rate (%f seconds)",
+                inst->next_nke_attempt - now);
+      return 0;
+    }
+
+    inst->nke = NKC_CreateInstance(&inst->nts_address, inst->name, inst->cert_set);
+
+    inst->nke_attempts++;
+
+    if (!NKC_Start(inst->nke))
+      failed_start = 1;
+  }
+
+  update_next_nke_attempt(inst, failed_start, now);
+
+  /* Wait until the session stops */
+  if (NKC_IsActive(inst->nke))
+    return 0;
+
+  assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
+  /* Get the new keys, cookies and NTP address if the session was successful */
+  got_data = NKC_GetNtsData(inst->nke, &inst->context,
+                            inst->cookies, &inst->num_cookies, NTS_MAX_COOKIES,
+                            &ntp_address);
+
+  NKC_DestroyInstance(inst->nke);
+  inst->nke = NULL;
+
+  if (!got_data)
+    return 0;
+
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->context_id++;
+
+  /* Force a new session if the NTP address is used by another source, with
+     an expectation that it will eventually get a non-conflicting address */
+  if (!set_ntp_address(inst, &ntp_address)) {
+    inst->num_cookies = 0;
+    return 0;
+  }
+
+  inst->last_nke_success = now;
+  inst->cookie_index = 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNC_PrepareForAuth(NNC_Instance inst)
+{
+  inst->auth_ready = 0;
+
+  /* Prepare data for the next request and invalidate any responses to the
+     previous request */
+  UTI_GetRandomBytes(inst->uniq_id, sizeof (inst->uniq_id));
+  UTI_GetRandomBytes(inst->nonce, sizeof (inst->nonce));
+
+  /* Get new cookies if there are not any, or they are no longer usable */
+  if (!check_cookies(inst)) {
+    if (!get_cookies(inst))
+      return 0;
+  }
+
+  inst->nak_response = 0;
+
+  if (!inst->siv)
+    inst->siv = SIV_CreateInstance(inst->context.algorithm);
+
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.c2s.key, inst->context.c2s.length)) {
+    DEBUG_LOG("Could not set SIV key");
+    return 0;
+  }
+
+  inst->auth_ready = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
+                        NTP_PacketInfo *info)
+{
+  NKE_Cookie *cookie;
+  int i, req_cookies;
+  void *ef_body;
+
+  if (!inst->auth_ready)
+    return 0;
+
+  inst->auth_ready = 0;
+
+  if (inst->num_cookies <= 0 || !inst->siv)
+    return 0;
+
+  if (info->mode != MODE_CLIENT)
+    return 0;
+
+  cookie = &inst->cookies[inst->cookie_index];
+  inst->num_cookies--;
+  inst->cookie_index = (inst->cookie_index + 1) % NTS_MAX_COOKIES;
+
+  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies,
+                    MAX_TOTAL_COOKIE_LENGTH / (cookie->length + 4));
+
+  if (!NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER,
+                    inst->uniq_id, sizeof (inst->uniq_id)))
+    return 0;
+
+  if (!NEF_AddField(packet, info, NTP_EF_NTS_COOKIE,
+                    cookie->cookie, cookie->length))
+    return 0;
+
+  for (i = 0; i < req_cookies - 1; i++) {
+    if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
+                           cookie->length, &ef_body))
+      return 0;
+    memset(ef_body, 0, cookie->length);
+  }
+
+  if (!NNA_GenerateAuthEF(packet, info, inst->siv, inst->nonce, sizeof (inst->nonce),
+                          (const unsigned char *)"", 0, NTP_MAX_V4_MAC_LENGTH + 4))
+    return 0;
+
+  inst->ok_response = 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+parse_encrypted_efs(NNC_Instance inst, unsigned char *plaintext, int length)
+{
+  int ef_length, parsed;
+
+  for (parsed = 0; parsed < length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, length, parsed, &ef_length, NULL, NULL, NULL)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+extract_cookies(NNC_Instance inst, unsigned char *plaintext, int length)
+{
+  int ef_type, ef_body_length, ef_length, parsed, index, acceptable, saved;
+  void *ef_body;
+
+  acceptable = saved = 0;
+
+  for (parsed = 0; parsed < length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, length, parsed,
+                              &ef_length, &ef_type, &ef_body, &ef_body_length))
+      return 0;
+
+    if (ef_type != NTP_EF_NTS_COOKIE)
+      continue;
+
+    if (ef_length < NTP_MIN_EF_LENGTH || ef_body_length > sizeof (inst->cookies[0].cookie)) {
+      DEBUG_LOG("Unexpected cookie length %d", ef_body_length);
+      continue;
+    }
+
+    acceptable++;
+
+    if (inst->num_cookies >= NTS_MAX_COOKIES)
+      continue;
+
+    index = (inst->cookie_index + inst->num_cookies) % NTS_MAX_COOKIES;
+    assert(index >= 0 && index < NTS_MAX_COOKIES);
+    assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
+    memcpy(inst->cookies[index].cookie, ef_body, ef_body_length);
+    inst->cookies[index].length = ef_body_length;
+    inst->num_cookies++;
+
+    saved++;
+  }
+
+  DEBUG_LOG("Extracted %d cookies (saved %d)", acceptable, saved);
+
+  return acceptable > 0;
+}
+
+/* ================================================== */
+
+int
+NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
+                      NTP_PacketInfo *info)
+{
+  int ef_type, ef_body_length, ef_length, parsed, plaintext_length;
+  int has_valid_uniq_id = 0, has_valid_auth = 0;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  void *ef_body;
+
+  if (info->ext_fields == 0 || info->mode != MODE_SERVER)
+    return 0;
+
+  /* Accept at most one response per request */
+  if (inst->ok_response || inst->auth_ready)
+    return 0;
+
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.s2c.key, inst->context.s2c.length)) {
+    DEBUG_LOG("Could not set SIV key");
+    return 0;
+  }
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed parsing */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        if (ef_body_length != sizeof (inst->uniq_id) ||
+            memcmp(ef_body, inst->uniq_id, sizeof (inst->uniq_id)) != 0) {
+          DEBUG_LOG("Invalid uniq id");
+          return 0;
+        }
+        has_valid_uniq_id = 1;
+        break;
+      case NTP_EF_NTS_COOKIE:
+        DEBUG_LOG("Unencrypted cookie");
+        break;
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        if (parsed + ef_length != info->length) {
+          DEBUG_LOG("Auth not last EF");
+          return 0;
+        }
+
+        if (!NNA_DecryptAuthEF(packet, info, inst->siv, parsed,
+                               plaintext, sizeof (plaintext), &plaintext_length))
+          return 0;
+
+        if (!parse_encrypted_efs(inst, plaintext, plaintext_length))
+          return 0;
+
+        has_valid_auth = 1;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!has_valid_uniq_id || !has_valid_auth) {
+    if (has_valid_uniq_id && packet->stratum == NTP_INVALID_STRATUM &&
+        ntohl(packet->reference_id) == NTP_KOD_NTS_NAK) {
+      DEBUG_LOG("NTS NAK");
+      inst->nak_response = 1;
+      return 0;
+    }
+
+    DEBUG_LOG("Missing NTS EF");
+    return 0;
+  }
+
+  if (!extract_cookies(inst, plaintext, plaintext_length))
+    return 0;
+
+  inst->ok_response = 1;
+
+  /* At this point we know the client interoperates with the server.  Allow a
+     new NTS-KE session to be started as soon as the cookies run out. */
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+NNC_ChangeAddress(NNC_Instance inst, IPAddr *address)
+{
+  save_cookies(inst);
+
+  inst->nts_address.ip_addr = *address;
+  inst->ntp_address.ip_addr = *address;
+
+  reset_instance(inst);
+
+  DEBUG_LOG("NTS reset");
+
+  load_cookies(inst);
+}
+
+/* ================================================== */
+
+static void
+save_cookies(NNC_Instance inst)
+{
+  char buf[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename;
+  struct timespec now;
+  double context_time;
+  FILE *f;
+  int i;
+
+  if (inst->num_cookies < 1 || !UTI_IsIPReal(&inst->nts_address.ip_addr))
+    return;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".tmp", 'w', 0600);
+  if (!f)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time = inst->last_nke_success - SCH_GetLastEventMonoTime();
+  context_time += UTI_TimespecToDouble(&now);
+
+  if (fprintf(f, "%s%s\n%.1f\n%s %d\n%u %d ",
+              DUMP_IDENTIFIER, inst->name, context_time,
+              UTI_IPToString(&inst->ntp_address.ip_addr), inst->ntp_address.port,
+              inst->context_id, (int)inst->context.algorithm) < 0 ||
+      !UTI_BytesToHex(inst->context.s2c.key, inst->context.s2c.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s ", buf) < 0 ||
+      !UTI_BytesToHex(inst->context.c2s.key, inst->context.c2s.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s\n", buf) < 0)
+    goto error;
+
+  for (i = 0; i < inst->num_cookies; i++) {
+    if (!UTI_BytesToHex(inst->cookies[i].cookie, inst->cookies[i].length, buf, sizeof (buf)) ||
+        fprintf(f, "%s\n", buf) < 0)
+      goto error;
+  }
+
+  fclose(f);
+
+  if (!UTI_RenameTempFile(dump_dir, filename, ".tmp", ".nts"))
+    ;
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "save", filename);
+  fclose(f);
+
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 4
+
+static void
+load_cookies(NNC_Instance inst)
+{
+  char line[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename, *words[MAX_WORDS];
+  unsigned int context_id;
+  int i, algorithm, port;
+  double context_time;
+  struct timespec now;
+  IPSockAddr ntp_addr;
+  FILE *f;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".nts", 'r', 0);
+  if (!f)
+    return;
+
+  /* Don't load this file again */
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        strcmp(words[0], inst->name) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        sscanf(words[0], "%lf", &context_time) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 2 ||
+        !UTI_StringToIP(words[0], &ntp_addr.ip_addr) || sscanf(words[1], "%d", &port) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 4 ||
+        sscanf(words[0], "%u", &context_id) != 1 || sscanf(words[1], "%d", &algorithm) != 1)
+    goto error;
+
+  inst->context.algorithm = algorithm;
+  inst->context.s2c.length = UTI_HexToBytes(words[2], inst->context.s2c.key,
+                                            sizeof (inst->context.s2c.key));
+  inst->context.c2s.length = UTI_HexToBytes(words[3], inst->context.c2s.key,
+                                            sizeof (inst->context.c2s.key));
+
+  if (inst->context.s2c.length != SIV_GetKeyLength(algorithm) ||
+      inst->context.s2c.length <= 0 ||
+      inst->context.c2s.length != inst->context.s2c.length)
+    goto error;
+
+  for (i = 0; i < NTS_MAX_COOKIES && fgets(line, sizeof (line), f); i++) {
+    if (UTI_SplitString(line, words, MAX_WORDS) != 1)
+      goto error;
+
+    inst->cookies[i].length = UTI_HexToBytes(words[0], inst->cookies[i].cookie,
+                                             sizeof (inst->cookies[i].cookie));
+    if (inst->cookies[i].length == 0)
+      goto error;
+  }
+
+  inst->num_cookies = i;
+
+  ntp_addr.port = port;
+  if (!set_ntp_address(inst, &ntp_addr))
+    goto error;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time -= UTI_TimespecToDouble(&now);
+  if (context_time > 0)
+    context_time = 0;
+  inst->last_nke_success = context_time + SCH_GetLastEventMonoTime();
+  inst->context_id = context_id;
+
+  fclose(f);
+
+  DEBUG_LOG("Loaded %d cookies for %s", i, filename);
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "load", filename);
+  fclose(f);
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->num_cookies = 0;
+}
+
+/* ================================================== */
+
+void
+NNC_DumpData(NNC_Instance inst)
+{
+  save_cookies(inst);
+}
+
+/* ================================================== */
+
+void
+NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report)
+{
+  report->key_id = inst->context_id;
+  report->key_type = inst->context.algorithm;
+  report->key_length = 8 * inst->context.s2c.length;
+  report->ke_attempts = inst->nke_attempts;
+  if (report->key_length > 0)
+    report->last_ke_ago = SCH_GetLastEventMonoTime() - inst->last_nke_success;
+  else
+    report->last_ke_ago = -1;
+  report->cookies = inst->num_cookies;
+  report->cookie_length = inst->num_cookies > 0 ? inst->cookies[inst->cookie_index].length : 0;
+  report->nak = inst->nak_response;
+}
diff --git a/nts_ntp_client.h b/nts_ntp_client.h
new file mode 100644
index 0000000..2c314cc
--- /dev/null
+++ b/nts_ntp_client.h
@@ -0,0 +1,51 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for client NTS-NTP authentication
+  */
+
+#ifndef GOT_NTS_NTP_CLIENT_H
+#define GOT_NTS_NTP_CLIENT_H
+
+#include "addressing.h"
+#include "ntp.h"
+#include "reports.h"
+
+typedef struct NNC_Instance_Record *NNC_Instance;
+
+extern NNC_Instance NNC_CreateInstance(IPSockAddr *nts_address, const char *name,
+                                       uint32_t cert_set, uint16_t ntp_port);
+extern void NNC_DestroyInstance(NNC_Instance inst);
+extern int NNC_PrepareForAuth(NNC_Instance inst);
+extern int NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
+                                   NTP_PacketInfo *info);
+extern int NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
+                                 NTP_PacketInfo *info);
+
+extern void NNC_ChangeAddress(NNC_Instance inst, IPAddr *address);
+
+extern void NNC_DumpData(NNC_Instance inst);
+
+extern void NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report);
+
+#endif
diff --git a/nts_ntp_server.c b/nts_ntp_server.c
new file mode 100644
index 0000000..be69a2b
--- /dev/null
+++ b/nts_ntp_server.c
@@ -0,0 +1,309 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Server NTS-NTP authentication
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "nts_ntp_server.h"
+
+#include "conf.h"
+#include "logging.h"
+#include "memory.h"
+#include "ntp.h"
+#include "ntp_ext.h"
+#include "nts_ke_server.h"
+#include "nts_ntp.h"
+#include "nts_ntp_auth.h"
+#include "siv.h"
+#include "util.h"
+
+#define MAX_SERVER_SIVS 2
+
+struct NtsServer {
+  SIV_Instance sivs[MAX_SERVER_SIVS];
+  SIV_Algorithm siv_algorithms[MAX_SERVER_SIVS];
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  NKE_Cookie cookies[NTS_MAX_COOKIES];
+  int num_cookies;
+  int siv_index;
+  NTP_int64 req_tx;
+};
+
+/* The server instance handling all requests */
+struct NtsServer *server;
+
+/* ================================================== */
+
+void
+NNS_Initialise(void)
+{
+  const char **certs, **keys;
+  int i;
+
+  /* Create an NTS-NTP server instance only if NTS-KE server is enabled */
+  if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0) {
+    server = NULL;
+    return;
+  }
+
+  server = Malloc(sizeof (struct NtsServer));
+
+  server->siv_algorithms[0] = AEAD_AES_SIV_CMAC_256;
+  server->siv_algorithms[1] = AEAD_AES_128_GCM_SIV;
+  assert(MAX_SERVER_SIVS == 2);
+
+  for (i = 0; i < 2; i++)
+    server->sivs[i] = SIV_CreateInstance(server->siv_algorithms[i]);
+
+  /* AES-SIV-CMAC-256 is required on servers */
+  if (!server->sivs[0])
+    LOG_FATAL("Missing AES-SIV-CMAC-256");
+}
+
+/* ================================================== */
+
+void
+NNS_Finalise(void)
+{
+  int i;
+
+  if (!server)
+    return;
+
+  for (i = 0; i < MAX_SERVER_SIVS; i++) {
+    if (server->sivs[i])
+      SIV_DestroyInstance(server->sivs[i]);
+  }
+  Free(server);
+  server = NULL;
+}
+
+/* ================================================== */
+
+int
+NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
+{
+  int ef_type, ef_body_length, ef_length, has_uniq_id = 0, has_auth = 0, has_cookie = 0;
+  int i, plaintext_length, parsed, requested_cookies, cookie_length = -1, auth_start = 0;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  NKE_Context context;
+  NKE_Cookie cookie;
+  SIV_Instance siv;
+  void *ef_body;
+
+  *kod = 0;
+
+  if (!server)
+    return 0;
+
+  server->num_cookies = 0;
+  server->siv_index = -1;
+  server->req_tx = packet->transmit_ts;
+
+  if (info->ext_fields == 0 || info->mode != MODE_CLIENT)
+    return 0;
+
+  requested_cookies = 0;
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
+    if (!NEF_ParseField(packet, info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed NAU_ParsePacket() */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        has_uniq_id = 1;
+        break;
+      case NTP_EF_NTS_COOKIE:
+        if (has_cookie || ef_body_length > sizeof (cookie.cookie)) {
+          DEBUG_LOG("Unexpected cookie/length");
+          return 0;
+        }
+        cookie.length = ef_body_length;
+        memcpy(cookie.cookie, ef_body, ef_body_length);
+        has_cookie = 1;
+        /* Fall through */
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+        requested_cookies++;
+
+        if (cookie_length >= 0 && cookie_length != ef_body_length) {
+          DEBUG_LOG("Invalid cookie/placeholder length");
+          return 0;
+        }
+        cookie_length = ef_body_length;
+        break;
+      case NTP_EF_NTS_AUTH_AND_EEF:
+        if (parsed + ef_length != info->length) {
+          DEBUG_LOG("Auth not last EF");
+          return 0;
+        }
+
+        auth_start = parsed;
+        has_auth = 1;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!has_uniq_id || !has_cookie || !has_auth) {
+    DEBUG_LOG("Missing an NTS EF");
+    return 0;
+  }
+
+  if (!NKS_DecodeCookie(&cookie, &context)) {
+    *kod = NTP_KOD_NTS_NAK;
+    return 0;
+  }
+
+  /* Find the SIV instance needed for authentication */
+  for (i = 0; i < MAX_SERVER_SIVS && context.algorithm != server->siv_algorithms[i]; i++)
+    ;
+  if (i == MAX_SERVER_SIVS || !server->sivs[i]) {
+    DEBUG_LOG("Unexpected SIV");
+    return 0;
+  }
+  server->siv_index = i;
+  siv = server->sivs[i];
+
+  if (!SIV_SetKey(siv, context.c2s.key, context.c2s.length)) {
+    DEBUG_LOG("Could not set C2S key");
+    return 0;
+  }
+
+  if (!NNA_DecryptAuthEF(packet, info, siv, auth_start,
+                         plaintext, sizeof (plaintext), &plaintext_length)) {
+    *kod = NTP_KOD_NTS_NAK;
+    return 0;
+  }
+
+  for (parsed = 0; parsed < plaintext_length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, plaintext_length, parsed,
+                              &ef_length, &ef_type, &ef_body, &ef_body_length)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }
+
+    switch (ef_type) {
+      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
+        if (cookie_length != ef_body_length) {
+          DEBUG_LOG("Invalid cookie/placeholder length");
+          return 0;
+        }
+        requested_cookies++;
+        break;
+      default:
+        break;
+    }
+  }
+
+  if (!SIV_SetKey(siv, context.s2c.key, context.s2c.length)) {
+    DEBUG_LOG("Could not set S2C key");
+    return 0;
+  }
+
+  /* Prepare data for NNS_GenerateResponseAuth() to minimise the time spent
+     there (when the TX timestamp is already set) */
+
+  UTI_GetRandomBytes(server->nonce, sizeof (server->nonce));
+
+  assert(sizeof (server->cookies) / sizeof (server->cookies[0]) == NTS_MAX_COOKIES);
+  for (i = 0; i < NTS_MAX_COOKIES && i < requested_cookies; i++)
+    if (!NKS_GenerateCookie(&context, &server->cookies[i]))
+      return 0;
+
+  server->num_cookies = i;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                         NTP_Packet *response, NTP_PacketInfo *res_info,
+                         uint32_t kod)
+{
+  int i, ef_type, ef_body_length, ef_length, parsed;
+  void *ef_body;
+  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  int plaintext_length;
+
+  if (!server || req_info->mode != MODE_CLIENT || res_info->mode != MODE_SERVER)
+    return 0;
+
+  /* Make sure this is a response to the request from the last call
+     of NNS_CheckRequestAuth() */
+  if (UTI_CompareNtp64(&server->req_tx, &request->transmit_ts) != 0)
+    assert(0);
+
+  for (parsed = NTP_HEADER_LENGTH; parsed < req_info->length; parsed += ef_length) {
+    if (!NEF_ParseField(request, req_info->length, parsed,
+                        &ef_length, &ef_type, &ef_body, &ef_body_length))
+      /* This is not expected as the packet already passed parsing */
+      return 0;
+
+    switch (ef_type) {
+      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
+        /* Copy the ID from the request */
+        if (!NEF_AddField(response, res_info, ef_type, ef_body, ef_body_length))
+          return 0;
+      default:
+        break;
+    }
+  }
+
+  /* NTS NAK response does not have any other fields */
+  if (kod)
+    return 1;
+
+  for (i = 0, plaintext_length = 0; i < server->num_cookies; i++) {
+    if (!NEF_SetField(plaintext, sizeof (plaintext), plaintext_length,
+                      NTP_EF_NTS_COOKIE, server->cookies[i].cookie,
+                      server->cookies[i].length, &ef_length))
+      return 0;
+
+    plaintext_length += ef_length;
+    assert(plaintext_length <= sizeof (plaintext));
+  }
+
+  server->num_cookies = 0;
+
+  if (server->siv_index < 0)
+    return 0;
+
+  /* Generate an authenticator field which will make the length
+     of the response equal to the length of the request */
+  if (!NNA_GenerateAuthEF(response, res_info, server->sivs[server->siv_index],
+                          server->nonce, sizeof (server->nonce),
+                          plaintext, plaintext_length,
+                          req_info->length - res_info->length))
+    return 0;
+
+  return 1;
+}
diff --git a/nts_ntp_server.h b/nts_ntp_server.h
new file mode 100644
index 0000000..fea28f2
--- /dev/null
+++ b/nts_ntp_server.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for server NTS-NTP authentication
+  */
+
+#ifndef GOT_NTS_NTP_SERVER_H
+#define GOT_NTS_NTP_SERVER_H
+
+#include "ntp.h"
+
+extern void NNS_Initialise(void);
+extern void NNS_Finalise(void);
+
+extern int NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod);
+extern int NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                                    NTP_Packet *response, NTP_PacketInfo *res_info,
+                                    uint32_t kod);
+
+#endif
diff --git a/pktlength.c b/pktlength.c
new file mode 100644
index 0000000..d7ed272
--- /dev/null
+++ b/pktlength.c
@@ -0,0 +1,222 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines to compute the expected length of a command or reply packet.
+  These operate on the RAW NETWORK packets, from the point of view of
+  integer endianness within the structures.
+
+  */
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "util.h"
+#include "pktlength.h"
+
+#define PADDING_LENGTH_(request_length, reply_length) \
+  (uint16_t)((request_length) < (reply_length) ? (reply_length) - (request_length) : 0)
+
+#define PADDING_LENGTH(request_data, reply_data) \
+  PADDING_LENGTH_(offsetof(CMD_Request, request_data), offsetof(CMD_Reply, reply_data))
+
+#define REQ_LENGTH_ENTRY(request_data_field, reply_data_field) \
+  { offsetof(CMD_Request, data.request_data_field.EOR), \
+    PADDING_LENGTH(data.request_data_field.EOR, data.reply_data_field.EOR) }
+
+#define RPY_LENGTH_ENTRY(reply_data_field) \
+  offsetof(CMD_Reply, data.reply_data_field.EOR)
+
+/* ================================================== */
+
+struct request_length {
+  uint16_t command;
+  uint16_t padding;
+};
+
+static const struct request_length request_lengths[] = {
+  REQ_LENGTH_ENTRY(null, null),                 /* NULL */
+  REQ_LENGTH_ENTRY(online, null),               /* ONLINE */
+  REQ_LENGTH_ENTRY(offline, null),              /* OFFLINE */
+  REQ_LENGTH_ENTRY(burst, null),                /* BURST */
+  REQ_LENGTH_ENTRY(modify_minpoll, null),       /* MODIFY_MINPOLL */
+  REQ_LENGTH_ENTRY(modify_maxpoll, null),       /* MODIFY_MAXPOLL */
+  REQ_LENGTH_ENTRY(dump, null),                 /* DUMP */
+  REQ_LENGTH_ENTRY(modify_maxdelay, null),      /* MODIFY_MAXDELAY */
+  REQ_LENGTH_ENTRY(modify_maxdelayratio, null), /* MODIFY_MAXDELAYRATIO */
+  REQ_LENGTH_ENTRY(modify_maxupdateskew, null), /* MODIFY_MAXUPDATESKEW */
+  REQ_LENGTH_ENTRY(logon, null),                /* LOGON */
+  REQ_LENGTH_ENTRY(settime, manual_timestamp),  /* SETTIME */
+  { 0, 0 },                                     /* LOCAL */
+  REQ_LENGTH_ENTRY(manual, null),               /* MANUAL */
+  REQ_LENGTH_ENTRY(null, n_sources),            /* N_SOURCES */
+  REQ_LENGTH_ENTRY(source_data, source_data),   /* SOURCE_DATA */
+  REQ_LENGTH_ENTRY(null, null),                 /* REKEY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* ALLOW */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* ALLOWALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* DENY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* DENYALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDALLOW */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDALLOWALL */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDDENY */
+  REQ_LENGTH_ENTRY(allow_deny, null),           /* CMDDENYALL */
+  REQ_LENGTH_ENTRY(ac_check, null),             /* ACCHECK */
+  REQ_LENGTH_ENTRY(ac_check, null),             /* CMDACCHECK */
+  { 0, 0 },                                     /* ADD_SERVER */
+  { 0, 0 },                                     /* ADD_PEER */
+  REQ_LENGTH_ENTRY(del_source, null),           /* DEL_SOURCE */
+  REQ_LENGTH_ENTRY(null, null),                 /* WRITERTC */
+  REQ_LENGTH_ENTRY(dfreq, null),                /* DFREQ */
+  { 0, 0 },                                     /* DOFFSET - not supported */
+  REQ_LENGTH_ENTRY(null, tracking),             /* TRACKING */
+  REQ_LENGTH_ENTRY(sourcestats, sourcestats),   /* SOURCESTATS */
+  REQ_LENGTH_ENTRY(null, rtc),                  /* RTCREPORT */
+  REQ_LENGTH_ENTRY(null, null),                 /* TRIMRTC */
+  REQ_LENGTH_ENTRY(null, null),                 /* CYCLELOGS */
+  { 0, 0 },                                     /* SUBNETS_ACCESSED - not supported */
+  { 0, 0 },                                     /* CLIENT_ACCESSES - not supported */
+  { 0, 0 },                                     /* CLIENT_ACCESSES_BY_INDEX - not supported */
+  REQ_LENGTH_ENTRY(null, manual_list),          /* MANUAL_LIST */
+  REQ_LENGTH_ENTRY(manual_delete, null),        /* MANUAL_DELETE */
+  REQ_LENGTH_ENTRY(null, null),                 /* MAKESTEP */
+  REQ_LENGTH_ENTRY(null, activity),             /* ACTIVITY */
+  REQ_LENGTH_ENTRY(modify_minstratum, null),    /* MODIFY_MINSTRATUM */
+  REQ_LENGTH_ENTRY(modify_polltarget, null),    /* MODIFY_POLLTARGET */
+  REQ_LENGTH_ENTRY(modify_maxdelaydevratio, null), /* MODIFY_MAXDELAYDEVRATIO */
+  REQ_LENGTH_ENTRY(null, null),                 /* RESELECT */
+  REQ_LENGTH_ENTRY(reselect_distance, null),    /* RESELECTDISTANCE */
+  REQ_LENGTH_ENTRY(modify_makestep, null),      /* MODIFY_MAKESTEP */
+  REQ_LENGTH_ENTRY(null, smoothing),            /* SMOOTHING */
+  REQ_LENGTH_ENTRY(smoothtime, null),           /* SMOOTHTIME */
+  REQ_LENGTH_ENTRY(null, null),                 /* REFRESH */
+  REQ_LENGTH_ENTRY(null, server_stats),         /* SERVER_STATS */
+  { 0, 0 },                                     /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
+  REQ_LENGTH_ENTRY(local, null),                /* LOCAL2 */
+  REQ_LENGTH_ENTRY(ntp_data, ntp_data),         /* NTP_DATA */
+  { 0, 0 },                                     /* ADD_SERVER2 */
+  { 0, 0 },                                     /* ADD_PEER2 */
+  { 0, 0 },                                     /* ADD_SERVER3 */
+  { 0, 0 },                                     /* ADD_PEER3 */
+  REQ_LENGTH_ENTRY(null, null),                 /* SHUTDOWN */
+  REQ_LENGTH_ENTRY(null, null),                 /* ONOFFLINE */
+  REQ_LENGTH_ENTRY(ntp_source, null),           /* ADD_SOURCE */
+  REQ_LENGTH_ENTRY(ntp_source_name,
+                   ntp_source_name),            /* NTP_SOURCE_NAME */
+  REQ_LENGTH_ENTRY(null, null),                 /* RESET_SOURCES */
+  REQ_LENGTH_ENTRY(auth_data, auth_data),       /* AUTH_DATA */
+  REQ_LENGTH_ENTRY(client_accesses_by_index,
+                   client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  REQ_LENGTH_ENTRY(select_data, select_data),   /* SELECT_DATA */
+  REQ_LENGTH_ENTRY(null, null),                 /* RELOAD_SOURCES */
+  REQ_LENGTH_ENTRY(doffset, null),              /* DOFFSET2 */
+  REQ_LENGTH_ENTRY(modify_select_opts, null),   /* MODIFY_SELECTOPTS */
+};
+
+static const uint16_t reply_lengths[] = {
+  0,                                            /* empty slot */
+  RPY_LENGTH_ENTRY(null),                       /* NULL */
+  RPY_LENGTH_ENTRY(n_sources),                  /* N_SOURCES */
+  RPY_LENGTH_ENTRY(source_data),                /* SOURCE_DATA */
+  0,                                            /* MANUAL_TIMESTAMP */
+  RPY_LENGTH_ENTRY(tracking),                   /* TRACKING */
+  RPY_LENGTH_ENTRY(sourcestats),                /* SOURCESTATS */
+  RPY_LENGTH_ENTRY(rtc),                        /* RTC */
+  0,                                            /* SUBNETS_ACCESSED - not supported */
+  0,                                            /* CLIENT_ACCESSES - not supported */
+  0,                                            /* CLIENT_ACCESSES_BY_INDEX - not supported */
+  0,                                            /* MANUAL_LIST - not supported */
+  RPY_LENGTH_ENTRY(activity),                   /* ACTIVITY */
+  RPY_LENGTH_ENTRY(smoothing),                  /* SMOOTHING */
+  0,                                            /* SERVER_STATS - not supported */
+  0,                                            /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
+  RPY_LENGTH_ENTRY(ntp_data),                   /* NTP_DATA */
+  RPY_LENGTH_ENTRY(manual_timestamp),           /* MANUAL_TIMESTAMP2 */
+  RPY_LENGTH_ENTRY(manual_list),                /* MANUAL_LIST2 */
+  RPY_LENGTH_ENTRY(ntp_source_name),            /* NTP_SOURCE_NAME */
+  RPY_LENGTH_ENTRY(auth_data),                  /* AUTH_DATA */
+  RPY_LENGTH_ENTRY(client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  0,                                            /* SERVER_STATS2 - not supported */
+  RPY_LENGTH_ENTRY(select_data),                /* SELECT_DATA */
+  0,                                            /* SERVER_STATS3 - not supported */
+  RPY_LENGTH_ENTRY(server_stats),               /* SERVER_STATS4 */
+};
+
+/* ================================================== */
+
+int
+PKL_CommandLength(CMD_Request *r)
+{
+  uint32_t type;
+  int command_length;
+
+  assert(sizeof (request_lengths) / sizeof (request_lengths[0]) == N_REQUEST_TYPES);
+
+  type = ntohs(r->command);
+  if (type >= N_REQUEST_TYPES)
+    return 0;
+
+  command_length = request_lengths[type].command;
+  if (!command_length)
+    return 0;
+
+  return command_length + PKL_CommandPaddingLength(r);
+}
+
+/* ================================================== */
+
+int
+PKL_CommandPaddingLength(CMD_Request *r)
+{
+  uint32_t type;
+
+  if (r->version < PROTO_VERSION_PADDING)
+    return 0;
+
+  type = ntohs(r->command);
+
+  if (type >= N_REQUEST_TYPES)
+    return 0;
+
+  return request_lengths[ntohs(r->command)].padding;
+}
+
+/* ================================================== */
+
+int
+PKL_ReplyLength(CMD_Reply *r)
+{
+  uint32_t type;
+
+  assert(sizeof (reply_lengths) / sizeof (reply_lengths[0]) == N_REPLY_TYPES);
+
+  type = ntohs(r->reply);
+
+  /* Note that reply type codes start from 1, not 0 */
+  if (type < 1 || type >= N_REPLY_TYPES)
+    return 0;
+
+  return reply_lengths[type];
+}
+
+/* ================================================== */
+
diff --git a/pktlength.h b/pktlength.h
new file mode 100644
index 0000000..fad4c30
--- /dev/null
+++ b/pktlength.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header for pktlength.c, routines for working out the expected length
+  of a network command/reply packet.
+
+  */
+
+#ifndef GOT_PKTLENGTH_H
+#define GOT_PKTLENGTH_H
+
+#include "candm.h"
+
+extern int PKL_CommandLength(CMD_Request *r);
+
+extern int PKL_CommandPaddingLength(CMD_Request *r);
+
+extern int PKL_ReplyLength(CMD_Reply *r);
+
+#endif /* GOT_PKTLENGTH_H */
diff --git a/privops.c b/privops.c
new file mode 100644
index 0000000..3fb5cbd
--- /dev/null
+++ b/privops.c
@@ -0,0 +1,696 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ * Copyright (C) Miroslav Lichvar  2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "nameserv.h"
+#include "logging.h"
+#include "privops.h"
+#include "socket.h"
+#include "util.h"
+
+#define OP_ADJUSTTIME     1024
+#define OP_ADJUSTTIMEX    1025
+#define OP_SETTIME        1026
+#define OP_BINDSOCKET     1027
+#define OP_NAME2IPADDRESS 1028
+#define OP_RELOADDNS      1029
+#define OP_QUIT           1099
+
+union sockaddr_in46 {
+  struct sockaddr_in in4;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 in6;
+#endif
+  struct sockaddr u;
+};
+
+/* daemon request structs */
+
+typedef struct {
+  struct timeval tv;
+} ReqAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ReqAdjustTimex;
+#endif
+
+typedef struct {
+  struct timeval tv;
+} ReqSetTime;
+
+typedef struct {
+  int sock;
+  socklen_t sa_len;
+  union sockaddr_in46 sa;
+} ReqBindSocket;
+
+typedef struct {
+  char name[256];
+} ReqName2IPAddress;
+
+typedef struct {
+  int op;
+  union {
+    ReqAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ReqAdjustTimex adjust_timex;
+#endif
+    ReqSetTime set_time;
+    ReqBindSocket bind_socket;
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ReqName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvRequest;
+
+/* helper response structs */
+
+typedef struct {
+  struct timeval tv;
+} ResAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ResAdjustTimex;
+#endif
+
+typedef struct {
+  IPAddr addresses[DNS_MAX_ADDRESSES];
+} ResName2IPAddress;
+
+typedef struct {
+  char msg[256];
+} ResFatalMsg;
+
+typedef struct {
+  int fatal_error;
+  int rc;
+  int res_errno;
+  union {
+    ResFatalMsg fatal_msg;
+    ResAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ResAdjustTimex adjust_timex;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ResName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvResponse;
+
+static int helper_fd;
+static pid_t helper_pid;
+
+static int
+have_helper(void)
+{
+  return helper_fd >= 0;
+}
+
+/* ======================================================================= */
+
+/* HELPER - prepare fatal error for daemon */
+static void
+res_fatal(PrvResponse *res, const char *fmt, ...)
+{
+  va_list ap;
+
+  res->fatal_error = 1;
+  va_start(ap, fmt);
+  vsnprintf(res->data.fatal_msg.msg, sizeof (res->data.fatal_msg.msg), fmt, ap);
+  va_end(ap);
+}
+
+/* ======================================================================= */
+
+/* HELPER - send response to the fd */
+
+static int
+send_response(int fd, const PrvResponse *res)
+{
+  if (SCK_Send(fd, res, sizeof (*res), 0) != sizeof (*res))
+    return 0;
+
+  return 1;
+}
+
+/* ======================================================================= */
+/* receive daemon request plus optional file descriptor over a unix socket */
+
+static int
+receive_from_daemon(int fd, PrvRequest *req)
+{
+  SCK_Message *message;
+
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message || message->length != sizeof (*req))
+    return 0;
+
+  memcpy(req, message->data, sizeof (*req));
+
+  if (req->op == OP_BINDSOCKET) {
+    req->data.bind_socket.sock = message->descriptor;
+
+    /* return error if valid descriptor not found */
+    if (req->data.bind_socket.sock < 0)
+      return 0;
+  } else if (message->descriptor >= 0) {
+    SCK_CloseSocket(message->descriptor);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ======================================================================= */
+
+/* HELPER - perform adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+static void
+do_adjust_time(const ReqAdjustTime *req, PrvResponse *res)
+{
+  res->rc = adjtime(&req->tv, &res->data.adjust_time.tv);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+static void
+do_adjust_timex(const ReqAdjustTimex *req, PrvResponse *res)
+{
+  res->data.adjust_timex.tmx = req->tmx;
+  res->rc = ntp_adjtime(&res->data.adjust_timex.tmx);
+  if (res->rc < 0)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+static void
+do_set_time(const ReqSetTime *req, PrvResponse *res)
+{
+  res->rc = settimeofday(&req->tv, NULL);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+static void
+do_bind_socket(ReqBindSocket *req, PrvResponse *res)
+{
+  IPSockAddr ip_saddr;
+  int sock_fd;
+  struct sockaddr *sa;
+  socklen_t sa_len;
+
+  sa = &req->sa.u;
+  sa_len = req->sa_len;
+  sock_fd = req->sock;
+
+  SCK_SockaddrToIPSockAddr(sa, sa_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort()) {
+    SCK_CloseSocket(sock_fd);
+    res_fatal(res, "Invalid port %d", ip_saddr.port);
+    return;
+  }
+
+  res->rc = bind(sock_fd, sa, sa_len);
+  if (res->rc)
+    res->res_errno = errno;
+
+  /* sock is still open on daemon side, but we're done with it in the helper */
+  SCK_CloseSocket(sock_fd);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+static void
+do_name_to_ipaddress(ReqName2IPAddress *req, PrvResponse *res)
+{
+  /* make sure the string is terminated */
+  req->name[sizeof (req->name) - 1] = '\0';
+
+  res->rc = DNS_Name2IPAddress(req->name, res->data.name_to_ipaddress.addresses,
+                               DNS_MAX_ADDRESSES);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Reload() */
+
+#ifdef PRIVOPS_RELOADDNS
+static void
+do_reload_dns(PrvResponse *res)
+{
+  DNS_Reload();
+  res->rc = 0;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - main loop - action requests from the daemon */
+
+static void
+helper_main(int fd)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int quit = 0;
+
+  while (!quit) {
+    if (!receive_from_daemon(fd, &req))
+      /* read error or closed input - we cannot recover - give up */
+      break;
+
+    memset(&res, 0, sizeof (res));
+
+    switch (req.op) {
+#ifdef PRIVOPS_ADJUSTTIME
+      case OP_ADJUSTTIME:
+        do_adjust_time(&req.data.adjust_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_ADJUSTTIMEX
+      case OP_ADJUSTTIMEX:
+        do_adjust_timex(&req.data.adjust_timex, &res);
+        break;
+#endif
+#ifdef PRIVOPS_SETTIME
+      case OP_SETTIME:
+        do_set_time(&req.data.set_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_BINDSOCKET
+      case OP_BINDSOCKET:
+        do_bind_socket(&req.data.bind_socket, &res);
+        break;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+      case OP_NAME2IPADDRESS:
+        do_name_to_ipaddress(&req.data.name_to_ipaddress, &res);
+        break;
+#endif
+#ifdef PRIVOPS_RELOADDNS
+      case OP_RELOADDNS:
+        do_reload_dns(&res);
+        break;
+#endif
+      case OP_QUIT:
+        quit = 1;
+        continue;
+
+      default:
+        res_fatal(&res, "Unexpected operator %d", req.op);
+        break;
+    }
+
+    send_response(fd, &res);
+  }
+
+  SCK_CloseSocket(fd);
+  exit(0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - receive helper response */
+
+static void
+receive_response(PrvResponse *res)
+{
+  int resp_len;
+
+  resp_len = SCK_Receive(helper_fd, res, sizeof (*res), 0);
+  if (resp_len < 0)
+    LOG_FATAL("Could not read from helper : %s", strerror(errno));
+  if (resp_len != sizeof (*res))
+    LOG_FATAL("Invalid helper response");
+
+  if (res->fatal_error)
+    LOG_FATAL("Error in helper : %s", res->data.fatal_msg.msg);
+
+  DEBUG_LOG("Received response rc=%d", res->rc);
+
+  /* if operation failed in the helper, set errno so daemon can print log message */
+  if (res->res_errno)
+    errno = res->res_errno;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request to the helper */
+
+static void
+send_request(PrvRequest *req)
+{
+  SCK_Message message;
+  int flags;
+
+  SCK_InitMessage(&message, SCK_ADDR_UNSPEC);
+
+  message.data = req;
+  message.length = sizeof (*req);
+  flags = 0;
+
+  if (req->op == OP_BINDSOCKET) {
+    /* send file descriptor as a control message */
+    message.descriptor = req->data.bind_socket.sock;
+    flags |= SCK_FLAG_MSG_DESCRIPTOR;
+  }
+
+  if (!SCK_SendMessage(helper_fd, &message, flags)) {
+    /* don't try to send another request from exit() */
+    helper_fd = -1;
+    LOG_FATAL("Could not send to helper : %s", strerror(errno));
+  }
+
+  DEBUG_LOG("Sent request op=%d", req->op);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request and wait for response */
+
+static void
+submit_request(PrvRequest *req, PrvResponse *res)
+{
+  send_request(req);
+  receive_response(res);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send the helper a request to exit and wait until it exits */
+
+static void
+stop_helper(void)
+{
+  PrvRequest req;
+  int status;
+
+  if (!have_helper())
+    return;
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_QUIT;
+  send_request(&req);
+
+  waitpid(helper_pid, &status, 0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - request adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+int
+PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper() || delta == NULL)
+    /* helper is not running or read adjustment call */
+    return adjtime(delta, olddelta);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIME;
+  req.data.adjust_time.tv = *delta;
+
+  submit_request(&req, &res);
+
+  if (olddelta)
+    *olddelta = res.data.adjust_time.tv;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+int
+PRV_AdjustTimex(struct timex *tmx)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper())
+    return ntp_adjtime(tmx);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIMEX;
+  req.data.adjust_timex.tmx = *tmx;
+
+  submit_request(&req, &res);
+
+  *tmx = res.data.adjust_timex.tmx;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+int
+PRV_SetTime(const struct timeval *tp, const struct timezone *tzp)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  /* only support setting the time */
+  assert(tp != NULL);
+  assert(tzp == NULL);
+
+  if (!have_helper())
+    return settimeofday(tp, NULL);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_SETTIME;
+  req.data.set_time.tv = *tp;
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+int
+PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len)
+{
+  IPSockAddr ip_saddr;
+  PrvRequest req;
+  PrvResponse res;
+
+  SCK_SockaddrToIPSockAddr(address, address_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort())
+    assert(0);
+
+  if (!have_helper())
+    return bind(sock, address, address_len);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_BINDSOCKET;
+  req.data.bind_socket.sock = sock;
+  req.data.bind_socket.sa_len = address_len;
+  assert(address_len <= sizeof (req.data.bind_socket.sa));
+  memcpy(&req.data.bind_socket.sa.u, address, address_len);
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+int
+PRV_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int i;
+
+  if (!have_helper())
+    return DNS_Name2IPAddress(name, ip_addrs, max_addrs);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_NAME2IPADDRESS;
+  if (snprintf(req.data.name_to_ipaddress.name, sizeof (req.data.name_to_ipaddress.name),
+               "%s", name) >= sizeof (req.data.name_to_ipaddress.name)) {
+    return DNS_Failure;
+  }
+
+  submit_request(&req, &res);
+
+  for (i = 0; i < max_addrs && i < DNS_MAX_ADDRESSES; i++)
+    ip_addrs[i] = res.data.name_to_ipaddress.addresses[i];
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request res_init() */
+
+#ifdef PRIVOPS_RELOADDNS
+void
+PRV_ReloadDNS(void)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper()) {
+    DNS_Reload();
+    return;
+  }
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_RELOADDNS;
+
+  submit_request(&req, &res);
+  assert(!res.rc);
+}
+#endif
+
+/* ======================================================================= */
+
+void
+PRV_Initialise(void)
+{
+  helper_fd = -1;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - setup socket(s) then fork to run the helper */
+/* must be called before privileges are dropped */
+
+void
+PRV_StartHelper(void)
+{
+  pid_t pid;
+  int fd, sock_fd1, sock_fd2;
+
+  if (have_helper())
+    LOG_FATAL("Helper already running");
+
+  sock_fd1 = SCK_OpenUnixSocketPair(SCK_FLAG_BLOCK, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");
+
+  pid = fork();
+  if (pid < 0)
+    LOG_FATAL("fork() failed : %s", strerror(errno));
+
+  if (pid == 0) {
+    /* child process */
+    SCK_CloseSocket(sock_fd1);
+
+    /* close other descriptors inherited from the parent process, except
+       stdin, stdout, and stderr */
+    for (fd = STDERR_FILENO + 1; fd < 1024; fd++) {
+      if (fd != sock_fd2)
+        close(fd);
+    }
+
+    UTI_ResetGetRandomFunctions();
+
+    /* ignore signals, the process will exit on OP_QUIT request */
+    UTI_SetQuitSignalsHandler(SIG_IGN, 1);
+
+    helper_main(sock_fd2);
+
+  } else {
+    /* parent process */
+    SCK_CloseSocket(sock_fd2);
+    helper_fd = sock_fd1;
+    helper_pid = pid;
+
+    /* stop the helper even when not exiting cleanly from the main function */
+    atexit(stop_helper);
+  }
+}
+
+/* ======================================================================= */
+
+/* DAEMON - graceful shutdown of the helper */
+
+void
+PRV_Finalise(void)
+{
+  if (!have_helper())
+    return;
+
+  stop_helper();
+  close(helper_fd);
+  helper_fd = -1;
+}
diff --git a/privops.h b/privops.h
new file mode 100644
index 0000000..146580b
--- /dev/null
+++ b/privops.h
@@ -0,0 +1,77 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+
+*/
+
+#ifndef GOT_PRIVOPS_H
+#define GOT_PRIVOPS_H
+
+#ifdef PRIVOPS_ADJUSTTIME
+int PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta);
+#else
+#define PRV_AdjustTime adjtime
+#endif
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+int PRV_AdjustTimex(struct timex *txc);
+#else
+#define PRV_AdjustTimex ntp_adjtime
+#endif
+
+#ifdef PRIVOPS_SETTIME
+int PRV_SetTime(const struct timeval *tp, const struct timezone *tzp);
+#else
+#define PRV_SetTime settimeofday
+#endif
+
+#ifdef PRIVOPS_BINDSOCKET
+int PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len);
+#else
+#define PRV_BindSocket bind
+#endif
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+int PRV_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs);
+#else
+#define PRV_Name2IPAddress DNS_Name2IPAddress
+#endif
+
+#ifdef PRIVOPS_RELOADDNS
+void PRV_ReloadDNS(void);
+#else
+#define PRV_ReloadDNS DNS_Reload
+#endif
+
+#ifdef PRIVOPS_HELPER
+void PRV_Initialise(void);
+void PRV_StartHelper(void);
+void PRV_Finalise(void);
+#else
+#define PRV_Initialise()
+#define PRV_StartHelper()
+#define PRV_Finalise()
+#endif
+
+#endif
diff --git a/ptp.h b/ptp.h
new file mode 100644
index 0000000..8034a2c
--- /dev/null
+++ b/ptp.h
@@ -0,0 +1,69 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the Precision Time Protocol (PTP).
+
+  */
+#ifndef GOT_PTP_H
+#define GOT_PTP_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+
+#define PTP_VERSION 2
+#define PTP_TYPE_DELAY_REQ 1
+#define PTP_DOMAIN_NTP 123
+#define PTP_FLAG_UNICAST (1 << (2 + 8))
+#define PTP_TLV_NTP 0x2023
+
+typedef struct {
+  uint8_t type;
+  uint8_t version;
+  uint16_t length;
+  uint8_t domain;
+  uint8_t min_sdoid;
+  uint16_t flags;
+  uint8_t correction[8];
+  uint8_t msg_specific[4];
+  uint8_t port_id[10];
+  uint16_t sequence_id;
+  uint8_t control;
+  int8_t interval;
+} PTP_Header;
+
+typedef struct {
+  uint16_t type;
+  uint16_t length;
+} PTP_TlvHeader;
+
+typedef struct {
+  PTP_Header header;
+  uint8_t origin_ts[10];
+  PTP_TlvHeader tlv_header;
+  NTP_Packet ntp_msg;
+} PTP_NtpMessage;
+
+#define PTP_NTP_PREFIX_LENGTH (int)offsetof(PTP_NtpMessage, ntp_msg)
+
+#endif
diff --git a/quantiles.c b/quantiles.c
new file mode 100644
index 0000000..52953db
--- /dev/null
+++ b/quantiles.c
@@ -0,0 +1,209 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Estimation of quantiles using the Frugal-2U streaming algorithm
+  (https://arxiv.org/pdf/1407.1121v1.pdf)
+  */
+
+#include "config.h"
+
+#include "logging.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "regress.h"
+#include "util.h"
+
+/* Maximum number of repeated estimates for stabilisation */
+#define MAX_REPEAT 64
+
+struct Quantile {
+  double est;
+  double step;
+  int sign;
+};
+
+struct QNT_Instance_Record {
+  struct Quantile *quants;
+  int n_quants;
+  int repeat;
+  int q;
+  int min_k;
+  double min_step;
+  int n_set;
+};
+
+/* ================================================== */
+
+QNT_Instance
+QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step)
+{
+  QNT_Instance inst;
+  long seed;
+
+  if (q < 2 || min_k > max_k || min_k < 1 || max_k >= q ||
+      repeat < 1 || repeat > MAX_REPEAT || min_step <= 0.0)
+    assert(0);
+
+  inst = MallocNew(struct QNT_Instance_Record);
+  inst->n_quants = (max_k - min_k + 1) * repeat;
+  inst->quants = MallocArray(struct Quantile, inst->n_quants);
+  inst->repeat = repeat;
+  inst->q = q;
+  inst->min_k = min_k;
+  inst->min_step = min_step;
+
+  QNT_Reset(inst);
+
+  /* Seed the random number generator, which will not be isolated from
+     other instances and other random() users */
+  UTI_GetRandomBytes(&seed, sizeof (seed));
+  srandom(seed);
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+QNT_DestroyInstance(QNT_Instance inst)
+{
+  Free(inst->quants);
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+QNT_Reset(QNT_Instance inst)
+{
+  int i;
+
+  inst->n_set = 0;
+
+  for (i = 0; i < inst->n_quants; i++) {
+    inst->quants[i].est = 0.0;
+    inst->quants[i].step = inst->min_step;
+    inst->quants[i].sign = 1;
+  }
+}
+
+/* ================================================== */
+
+static void
+insert_initial_value(QNT_Instance inst, double value)
+{
+  int i, j, r = inst->repeat;
+
+  if (inst->n_set * r >= inst->n_quants)
+    assert(0);
+
+  /* Keep the initial estimates repeated and ordered */
+  for (i = inst->n_set; i > 0 && inst->quants[(i - 1) * r].est > value; i--) {
+    for (j = 0; j < r; j++)
+      inst->quants[i * r + j].est = inst->quants[(i - 1) * r].est;
+  }
+
+  for (j = 0; j < r; j++)
+    inst->quants[i * r + j].est = value;
+  inst->n_set++;
+
+  /* Duplicate the largest value in unset quantiles */
+  for (i = inst->n_set * r; i < inst->n_quants; i++)
+    inst->quants[i].est = inst->quants[i - 1].est;
+}
+
+/* ================================================== */
+
+static void
+update_estimate(struct Quantile *quantile, double value, double p, double rand,
+                double min_step)
+{
+  if (value > quantile->est && rand > (1.0 - p)) {
+    quantile->step += quantile->sign > 0 ? min_step : -min_step;
+    quantile->est += quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est > value) {
+      quantile->step += value - quantile->est;
+      quantile->est = value;
+    }
+    if (quantile->sign < 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = 1;
+  } else if (value < quantile->est && rand > p) {
+    quantile->step += quantile->sign < 0 ? min_step : -min_step;
+    quantile->est -= quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est < value) {
+      quantile->step += quantile->est - value;
+      quantile->est = value;
+    }
+    if (quantile->sign > 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = -1;
+  }
+}
+
+/* ================================================== */
+
+void
+QNT_Accumulate(QNT_Instance inst, double value)
+{
+  double p, rand;
+  int i;
+
+  /* Initialise the estimates with first received values */
+  if (inst->n_set * inst->repeat < inst->n_quants) {
+    insert_initial_value(inst, value);
+    return;
+  }
+
+  for (i = 0; i < inst->n_quants; i++) {
+    p = (double)(i / inst->repeat + inst->min_k) / inst->q;
+    rand = (double)random() / ((1U << 31) - 1);
+
+    update_estimate(&inst->quants[i], value, p, rand, inst->min_step);
+  }
+}
+
+/* ================================================== */
+
+int
+QNT_GetMinK(QNT_Instance inst)
+{
+  return inst->min_k;
+}
+
+/* ================================================== */
+
+double
+QNT_GetQuantile(QNT_Instance inst, int k)
+{
+  double estimates[MAX_REPEAT];
+  int i;
+
+  if (k < inst->min_k || k - inst->min_k >= inst->n_quants)
+    assert(0);
+
+  for (i = 0; i < inst->repeat; i++)
+    estimates[i] = inst->quants[(k - inst->min_k) * inst->repeat + i].est;
+
+  return RGR_FindMedian(estimates, inst->repeat);
+}
diff --git a/quantiles.h b/quantiles.h
new file mode 100644
index 0000000..1788544
--- /dev/null
+++ b/quantiles.h
@@ -0,0 +1,41 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for estimation of quantiles.
+
+  */
+
+#ifndef GOT_QUANTILES_H
+#define GOT_QUANTILES_H
+
+typedef struct QNT_Instance_Record *QNT_Instance;
+
+extern QNT_Instance QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step);
+extern void QNT_DestroyInstance(QNT_Instance inst);
+
+extern void QNT_Reset(QNT_Instance inst);
+extern void QNT_Accumulate(QNT_Instance inst, double value);
+extern int QNT_GetMinK(QNT_Instance inst);
+extern double QNT_GetQuantile(QNT_Instance inst, int k);
+
+#endif
diff --git a/refclock.c b/refclock.c
new file mode 100644
index 0000000..84f7439
--- /dev/null
+++ b/refclock.c
@@ -0,0 +1,862 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009-2011, 2013-2014, 2016-2019, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing reference clocks.
+
+  */
+
+#include "config.h"
+
+#include "array.h"
+#include "refclock.h"
+#include "reference.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "util.h"
+#include "sources.h"
+#include "logging.h"
+#include "regress.h"
+#include "samplefilt.h"
+#include "sched.h"
+
+/* Maximum offset of locked reference as a fraction of the PPS interval */
+#define PPS_LOCK_LIMIT 0.4
+
+/* list of refclock drivers */
+extern RefclockDriver RCL_SHM_driver;
+extern RefclockDriver RCL_SOCK_driver;
+extern RefclockDriver RCL_PPS_driver;
+extern RefclockDriver RCL_PHC_driver;
+
+struct FilterSample {
+  double offset;
+  double dispersion;
+  struct timespec sample_time;
+};
+
+struct RCL_Instance_Record {
+  RefclockDriver *driver;
+  void *data;
+  char *driver_parameter;
+  int driver_parameter_length;
+  int driver_poll;
+  int driver_polled;
+  int poll;
+  int leap_status;
+  int local;
+  int pps_forced;
+  int pps_rate;
+  int pps_active;
+  int max_lock_age;
+  int stratum;
+  int tai;
+  uint32_t ref_id;
+  uint32_t lock_ref;
+  double offset;
+  double delay;
+  double precision;
+  double pulse_width;
+  SPF_Instance filter;
+  SCH_TimeoutID timeout_id;
+  SRC_Instance source;
+};
+
+/* Array of pointers to RCL_Instance_Record */
+static ARR_Instance refclocks;
+
+static LOG_FileID logfileid;
+
+static int valid_sample_time(RCL_Instance instance, struct timespec *sample_time);
+static int pps_stratum(RCL_Instance instance, struct timespec *ts);
+static void poll_timeout(void *arg);
+static void slew_samples(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything);
+static void add_dispersion(double dispersion, void *anything);
+static void log_sample(RCL_Instance instance, struct timespec *sample_time, int filtered, int pulse, double raw_offset, double cooked_offset, double dispersion);
+
+static RCL_Instance
+get_refclock(unsigned int index)
+{
+  return *(RCL_Instance *)ARR_GetElement(refclocks, index);
+}
+
+void
+RCL_Initialise(void)
+{
+  refclocks = ARR_CreateInstance(sizeof (RCL_Instance));
+
+  CNF_AddRefclocks();
+
+  if (ARR_GetSize(refclocks) > 0) {
+    LCL_AddParameterChangeHandler(slew_samples, NULL);
+    LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
+  }
+
+  logfileid = CNF_GetLogRefclocks() ? LOG_FileOpen("refclocks",
+      "   Date (UTC) Time         Refid  DP L P  Raw offset   Cooked offset      Disp.")
+    : -1;
+}
+
+void
+RCL_Finalise(void)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    RCL_Instance inst = get_refclock(i);
+
+    if (inst->driver->fini)
+      inst->driver->fini(inst);
+
+    SPF_DestroyInstance(inst->filter);
+    Free(inst->driver_parameter);
+    SRC_DestroyInstance(inst->source);
+    Free(inst);
+  }
+
+  if (ARR_GetSize(refclocks) > 0) {
+    LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+    LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
+  }
+
+  ARR_DestroyInstance(refclocks);
+}
+
+int
+RCL_AddRefclock(RefclockParameters *params)
+{
+  RCL_Instance inst;
+
+  inst = MallocNew(struct RCL_Instance_Record);
+  *(RCL_Instance *)ARR_GetNewElement(refclocks) = inst;
+
+  if (strcmp(params->driver_name, "SHM") == 0) {
+    inst->driver = &RCL_SHM_driver;
+  } else if (strcmp(params->driver_name, "SOCK") == 0) {
+    inst->driver = &RCL_SOCK_driver;
+  } else if (strcmp(params->driver_name, "PPS") == 0) {
+    inst->driver = &RCL_PPS_driver;
+  } else if (strcmp(params->driver_name, "PHC") == 0) {
+    inst->driver = &RCL_PHC_driver;
+  } else {
+    LOG_FATAL("unknown refclock driver %s", params->driver_name);
+  }
+
+  if (!inst->driver->init && !inst->driver->poll)
+    LOG_FATAL("refclock driver %s is not compiled in", params->driver_name);
+
+  if (params->tai && !CNF_GetLeapSecTimezone())
+    LOG_FATAL("refclock tai option requires leapsectz");
+
+  inst->data = NULL;
+  inst->driver_parameter = Strdup(params->driver_parameter);
+  inst->driver_parameter_length = 0;
+  inst->driver_poll = params->driver_poll;
+  inst->poll = params->poll;
+  inst->driver_polled = 0;
+  inst->leap_status = LEAP_Normal;
+  inst->local = params->local;
+  inst->pps_forced = params->pps_forced;
+  inst->pps_rate = params->pps_rate;
+  inst->pps_active = 0;
+  inst->max_lock_age = params->max_lock_age;
+  inst->stratum = params->stratum;
+  inst->tai = params->tai;
+  inst->lock_ref = params->lock_ref_id;
+  inst->offset = params->offset;
+  inst->delay = params->delay;
+  inst->precision = LCL_GetSysPrecisionAsQuantum();
+  inst->precision = MAX(inst->precision, params->precision);
+  inst->pulse_width = params->pulse_width;
+  inst->timeout_id = -1;
+  inst->source = NULL;
+
+  if (inst->driver_parameter) {
+    int i;
+
+    inst->driver_parameter_length = strlen(inst->driver_parameter);
+    for (i = 0; i < inst->driver_parameter_length; i++)
+      if (inst->driver_parameter[i] == ':')
+        inst->driver_parameter[i] = '\0';
+  }
+
+  if (inst->pps_rate < 1)
+    inst->pps_rate = 1;
+
+  if (params->ref_id)
+    inst->ref_id = params->ref_id;
+  else {
+    unsigned char ref[5] = { 0, 0, 0, 0, 0 };
+    unsigned int index = ARR_GetSize(refclocks) - 1;
+
+    snprintf((char *)ref, sizeof (ref), "%3.3s", params->driver_name);
+    ref[3] = index % 10 + '0';
+    if (index >= 10)
+      ref[2] = (index / 10) % 10 + '0';
+
+    inst->ref_id = (uint32_t)ref[0] << 24 | ref[1] << 16 | ref[2] << 8 | ref[3];
+  }
+
+  if (inst->local) {
+    inst->pps_forced = 1;
+    inst->lock_ref = inst->ref_id;
+    inst->leap_status = LEAP_Unsynchronised;
+    inst->max_lock_age = MAX(inst->max_lock_age, 3);
+  }
+
+  if (inst->driver->poll) {
+    int max_samples;
+
+    if (inst->driver_poll > inst->poll)
+      inst->driver_poll = inst->poll;
+
+    max_samples = 1 << (inst->poll - inst->driver_poll);
+    if (max_samples < params->filter_length) {
+      if (max_samples < 4) {
+        LOG(LOGS_WARN, "Setting filter length for %s to %d",
+            UTI_RefidToString(inst->ref_id), max_samples);
+      }
+      params->filter_length = max_samples;
+    }
+  }
+
+  if (inst->driver->init && !inst->driver->init(inst))
+    LOG_FATAL("refclock %s initialisation failed", params->driver_name);
+
+  /* Require the filter to have at least 4 samples to produce a filtered
+     sample, or be full for shorter lengths, and combine 60% of samples
+     closest to the median */
+  inst->filter = SPF_CreateInstance(MIN(params->filter_length, 4), params->filter_length,
+                                    params->max_dispersion, 0.6);
+
+  inst->source = SRC_CreateNewInstance(inst->ref_id, SRC_REFCLOCK, 0, params->sel_options,
+                                       NULL, params->min_samples, params->max_samples,
+                                       0.0, 0.0);
+
+  DEBUG_LOG("refclock %s refid=%s poll=%d dpoll=%d filter=%d",
+      params->driver_name, UTI_RefidToString(inst->ref_id),
+      inst->poll, inst->driver_poll, params->filter_length);
+
+  return 1;
+}
+
+void
+RCL_StartRefclocks(void)
+{
+  unsigned int i, j, n, lock_index;
+
+  n = ARR_GetSize(refclocks);
+
+  for (i = 0; i < n; i++) {
+    RCL_Instance inst = get_refclock(i);
+
+    SRC_SetActive(inst->source);
+    inst->timeout_id = SCH_AddTimeoutByDelay(0.0, poll_timeout, (void *)inst);
+
+    /* Replace lock refid with the refclock's index, or -1 if not valid */
+
+    lock_index = -1;
+
+    if (inst->lock_ref != 0) {
+      for (j = 0; j < n; j++) {
+        RCL_Instance inst2 = get_refclock(j);
+
+        if (inst->lock_ref != inst2->ref_id)
+          continue;
+
+        if (inst->driver->poll && inst2->driver->poll &&
+            (double)inst->max_lock_age / inst->pps_rate < UTI_Log2ToDouble(inst2->driver_poll))
+          LOG(LOGS_WARN, "%s maxlockage too small for %s",
+              UTI_RefidToString(inst->ref_id), UTI_RefidToString(inst2->ref_id));
+
+        lock_index = j;
+        break;
+      }
+
+      if (lock_index == -1 || (lock_index == i && !inst->local))
+        LOG(LOGS_WARN, "Invalid lock refid %s", UTI_RefidToString(inst->lock_ref));
+    }
+
+    inst->lock_ref = lock_index;
+  }
+}
+
+void
+RCL_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  unsigned int i;
+  uint32_t ref_id;
+
+  assert(report->ip_addr.family == IPADDR_INET4);
+  ref_id = report->ip_addr.addr.in4;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    RCL_Instance inst = get_refclock(i);
+    if (inst->ref_id == ref_id) {
+      report->poll = inst->poll;
+      report->mode = RPT_LOCAL_REFERENCE;
+      break;
+    }
+  }
+}
+
+void
+RCL_SetDriverData(RCL_Instance instance, void *data)
+{
+  instance->data = data;
+}
+
+void *
+RCL_GetDriverData(RCL_Instance instance)
+{
+  return instance->data;
+}
+
+char *
+RCL_GetDriverParameter(RCL_Instance instance)
+{
+  return instance->driver_parameter;
+}
+
+static char *
+get_next_driver_option(RCL_Instance instance, char *option)
+{
+  if (option == NULL)
+    option = instance->driver_parameter;
+
+  option += strlen(option) + 1;
+
+  if (option >= instance->driver_parameter + instance->driver_parameter_length)
+    return NULL;
+
+  return option;
+}
+
+void
+RCL_CheckDriverOptions(RCL_Instance instance, const char **options)
+{
+  char *option;
+  int i, len;
+
+  for (option = get_next_driver_option(instance, NULL);
+       option;
+       option = get_next_driver_option(instance, option)) {
+    for (i = 0; options && options[i]; i++) {
+      len = strlen(options[i]);
+      if (!strncmp(options[i], option, len) &&
+          (option[len] == '=' || option[len] == '\0'))
+        break;
+    }
+
+    if (!options || !options[i])
+      LOG_FATAL("Invalid refclock driver option %s", option);
+  }
+}
+
+char *
+RCL_GetDriverOption(RCL_Instance instance, char *name)
+{
+  char *option;
+  int len;
+
+  len = strlen(name);
+
+  for (option = get_next_driver_option(instance, NULL);
+       option;
+       option = get_next_driver_option(instance, option)) {
+    if (!strncmp(name, option, len)) {
+      if (option[len] == '=')
+        return option + len + 1;
+      if (option[len] == '\0')
+        return option + len;
+    }
+  }
+
+  return NULL;
+}
+
+static int
+convert_tai_offset(struct timespec *sample_time, double *offset)
+{
+  struct timespec tai_ts, utc_ts;
+  int tai_offset;
+
+  /* Get approximate TAI-UTC offset for the reference time in TAI */
+  UTI_AddDoubleToTimespec(sample_time, *offset, &tai_ts);
+  tai_offset = REF_GetTaiOffset(&tai_ts);
+
+  /* Get TAI-UTC offset for the reference time in UTC +/- 1 second */
+  UTI_AddDoubleToTimespec(&tai_ts, -tai_offset, &utc_ts);
+  tai_offset = REF_GetTaiOffset(&utc_ts);
+
+  if (!tai_offset)
+    return 0;
+
+  *offset -= tai_offset;
+
+  return 1;
+}
+
+static int
+accumulate_sample(RCL_Instance instance, struct timespec *sample_time, double offset, double dispersion)
+{
+  NTP_Sample sample;
+
+  sample.time = *sample_time;
+  sample.offset = offset;
+  sample.peer_delay = instance->delay;
+  sample.root_delay = instance->delay;
+  sample.peer_dispersion = dispersion;
+  sample.root_dispersion = dispersion;
+
+  return SPF_AccumulateSample(instance->filter, &sample);
+}
+
+int
+RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+              struct timespec *ref_time, int leap)
+{
+  double correction, dispersion, raw_offset, offset;
+  struct timespec cooked_time;
+
+  if (instance->pps_forced)
+    return RCL_AddPulse(instance, sample_time,
+                        1.0e-9 * (sample_time->tv_nsec - ref_time->tv_nsec));
+
+  raw_offset = UTI_DiffTimespecsToDouble(ref_time, sample_time);
+
+  LCL_GetOffsetCorrection(sample_time, &correction, &dispersion);
+  UTI_AddDoubleToTimespec(sample_time, correction, &cooked_time);
+  dispersion += instance->precision;
+
+  /* Make sure the timestamp and offset provided by the driver are sane */
+  if (!UTI_IsTimeOffsetSane(sample_time, raw_offset) ||
+      !valid_sample_time(instance, &cooked_time))
+    return 0;
+
+  switch (leap) {
+    case LEAP_Normal:
+    case LEAP_InsertSecond:
+    case LEAP_DeleteSecond:
+      instance->leap_status = leap;
+      break;
+    default:
+      DEBUG_LOG("refclock sample ignored bad leap %d", leap);
+      return 0;
+  }
+
+  /* Calculate offset = raw_offset - correction + instance->offset
+     in parts to avoid loss of precision if there are large differences */
+  offset = ref_time->tv_sec - sample_time->tv_sec -
+           (time_t)correction + (time_t)instance->offset;
+  offset += 1.0e-9 * (ref_time->tv_nsec - sample_time->tv_nsec) -
+            (correction - (time_t)correction) + (instance->offset - (time_t)instance->offset);
+
+  if (instance->tai && !convert_tai_offset(sample_time, &offset)) {
+    DEBUG_LOG("refclock sample ignored unknown TAI offset");
+    return 0;
+  }
+
+  if (!accumulate_sample(instance, &cooked_time, offset, dispersion))
+    return 0;
+
+  instance->pps_active = 0;
+
+  log_sample(instance, &cooked_time, 0, 0, raw_offset, offset, dispersion);
+
+  /* for logging purposes */
+  if (!instance->driver->poll)
+    instance->driver_polled++;
+
+  return 1;
+}
+
+int
+RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second)
+{
+  double correction, dispersion;
+  struct timespec cooked_time;
+
+  LCL_GetOffsetCorrection(pulse_time, &correction, &dispersion);
+  UTI_AddDoubleToTimespec(pulse_time, correction, &cooked_time);
+  second += correction;
+
+  if (!UTI_IsTimeOffsetSane(pulse_time, 0.0))
+    return 0;
+
+  return RCL_AddCookedPulse(instance, &cooked_time, second, dispersion, correction);
+}
+
+static int
+check_pulse_edge(RCL_Instance instance, double offset, double distance)
+{
+  double max_error;
+
+  if (instance->pulse_width <= 0.0)
+    return 1;
+
+  max_error = 1.0 / instance->pps_rate - instance->pulse_width;
+  max_error = MIN(instance->pulse_width, max_error);
+  max_error *= 0.5;
+
+  if (fabs(offset) > max_error || distance > max_error) {
+      DEBUG_LOG("refclock pulse ignored offset=%.9f distance=%.9f max_error=%.9f",
+                offset, distance, max_error);
+      return 0;
+  }
+
+  return 1;
+}
+
+int
+RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
+                   double second, double dispersion, double raw_correction)
+{
+  double offset;
+  int rate;
+  NTP_Leap leap;
+
+  if (!UTI_IsTimeOffsetSane(cooked_time, second) ||
+      !valid_sample_time(instance, cooked_time))
+    return 0;
+
+  leap = LEAP_Normal;
+  dispersion += instance->precision;
+  rate = instance->pps_rate;
+
+  offset = -second + instance->offset;
+
+  /* Adjust the offset to [-0.5/rate, 0.5/rate) interval */
+  offset -= (long)(offset * rate) / (double)rate;
+  if (offset < -0.5 / rate)
+    offset += 1.0 / rate;
+  else if (offset >= 0.5 / rate)
+    offset -= 1.0 / rate;
+
+  if (instance->lock_ref != -1) {
+    RCL_Instance lock_refclock;
+    NTP_Sample ref_sample;
+    double sample_diff, shift;
+
+    lock_refclock = get_refclock(instance->lock_ref);
+
+    if (!SPF_GetLastSample(lock_refclock->filter, &ref_sample)) {
+      if (instance->local) {
+        /* Make the first sample in order to lock to itself */
+        ref_sample.time = *cooked_time;
+        ref_sample.offset = offset;
+        ref_sample.peer_delay = ref_sample.peer_dispersion = 0;
+        ref_sample.root_delay = ref_sample.root_dispersion = 0;
+      } else {
+        DEBUG_LOG("refclock pulse ignored no ref sample");
+        return 0;
+      }
+    }
+
+    ref_sample.root_dispersion += SPF_GetAvgSampleDispersion(lock_refclock->filter);
+
+    sample_diff = UTI_DiffTimespecsToDouble(cooked_time, &ref_sample.time);
+    if (fabs(sample_diff) >= (double)instance->max_lock_age / rate) {
+      DEBUG_LOG("refclock pulse ignored samplediff=%.9f", sample_diff);
+
+      /* Restart the local mode */
+      if (instance->local) {
+        LOG(LOGS_WARN, "Local refclock lost lock");
+        SPF_DropSamples(instance->filter);
+        SRC_ResetInstance(instance->source);
+      }
+      return 0;
+    }
+
+    /* Align the offset to the reference sample */
+    shift = round((ref_sample.offset - offset) * rate) / rate;
+
+    offset += shift;
+
+    if (fabs(ref_sample.offset - offset) +
+        ref_sample.root_dispersion + dispersion > PPS_LOCK_LIMIT / rate) {
+      DEBUG_LOG("refclock pulse ignored offdiff=%.9f refdisp=%.9f disp=%.9f",
+                ref_sample.offset - offset, ref_sample.root_dispersion, dispersion);
+      return 0;
+    }
+
+    if (!check_pulse_edge(instance, ref_sample.offset - offset, 0.0))
+      return 0;
+
+    leap = lock_refclock->leap_status;
+
+    DEBUG_LOG("refclock pulse offset=%.9f offdiff=%.9f samplediff=%.9f",
+              offset, ref_sample.offset - offset, sample_diff);
+  } else {
+    struct timespec ref_time;
+    int is_synchronised, stratum;
+    double root_delay, root_dispersion, distance;
+    uint32_t ref_id;
+
+    /* Ignore the pulse if we are not well synchronized and the local
+       reference is not active */
+
+    REF_GetReferenceParams(cooked_time, &is_synchronised, &leap, &stratum,
+        &ref_id, &ref_time, &root_delay, &root_dispersion);
+    distance = fabs(root_delay) / 2 + root_dispersion;
+
+    if (leap == LEAP_Unsynchronised || distance >= 0.5 / rate) {
+      DEBUG_LOG("refclock pulse ignored offset=%.9f sync=%d dist=%.9f",
+                offset, leap != LEAP_Unsynchronised, distance);
+      /* Drop also all stored samples */
+      SPF_DropSamples(instance->filter);
+      return 0;
+    }
+
+    if (!check_pulse_edge(instance, offset, distance))
+      return 0;
+  }
+
+  if (!accumulate_sample(instance, cooked_time, offset, dispersion))
+    return 0;
+
+  instance->leap_status = leap;
+  instance->pps_active = 1;
+
+  log_sample(instance, cooked_time, 0, 1, offset + raw_correction - instance->offset,
+             offset, dispersion);
+
+  /* for logging purposes */
+  if (!instance->driver->poll)
+    instance->driver_polled++;
+
+  return 1;
+}
+
+double
+RCL_GetPrecision(RCL_Instance instance)
+{
+  return instance->precision;
+}
+
+int
+RCL_GetDriverPoll(RCL_Instance instance)
+{
+  return instance->driver_poll;
+}
+
+static int
+valid_sample_time(RCL_Instance instance, struct timespec *sample_time)
+{
+  struct timespec now;
+  double diff;
+
+  LCL_ReadCookedTime(&now, NULL);
+  diff = UTI_DiffTimespecsToDouble(&now, sample_time);
+
+  if (diff < 0.0 || diff > UTI_Log2ToDouble(instance->poll + 1)) {
+    DEBUG_LOG("%s refclock sample time %s not valid age=%.6f",
+              UTI_RefidToString(instance->ref_id),
+              UTI_TimespecToString(sample_time), diff);
+    return 0;
+  }
+
+  return 1;
+}
+
+static int
+pps_stratum(RCL_Instance instance, struct timespec *ts)
+{
+  struct timespec ref_time;
+  int is_synchronised, stratum;
+  unsigned int i;
+  double root_delay, root_dispersion;
+  NTP_Leap leap;
+  uint32_t ref_id;
+  RCL_Instance refclock;
+
+  REF_GetReferenceParams(ts, &is_synchronised, &leap, &stratum,
+      &ref_id, &ref_time, &root_delay, &root_dispersion);
+
+  /* Don't change our stratum if the local reference is active
+     or this is the current source */
+  if (ref_id == instance->ref_id ||
+      (!is_synchronised && leap != LEAP_Unsynchronised))
+    return stratum - 1;
+
+  /* Or the current source is another PPS refclock */ 
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    refclock = get_refclock(i);
+    if (refclock->ref_id == ref_id &&
+        refclock->pps_active && refclock->lock_ref == -1)
+      return stratum - 1;
+  }
+
+  return 0;
+}
+
+static void
+get_local_stats(RCL_Instance inst, struct timespec *ref, double *freq, double *offset)
+{
+  double offset_sd, freq_sd, skew, root_delay, root_disp;
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+
+  if (SST_Samples(stats) < SST_GetMinSamples(stats)) {
+    UTI_ZeroTimespec(ref);
+    return;
+  }
+
+  SST_GetTrackingData(stats, ref, offset, &offset_sd, freq, &freq_sd,
+                      &skew, &root_delay, &root_disp);
+}
+
+static void
+follow_local(RCL_Instance inst, struct timespec *prev_ref_time, double prev_freq,
+             double prev_offset)
+{
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+  double freq, dfreq, offset, doffset, elapsed;
+  struct timespec now, ref_time;
+
+  get_local_stats(inst, &ref_time, &freq, &offset);
+
+  if (UTI_IsZeroTimespec(prev_ref_time) || UTI_IsZeroTimespec(&ref_time))
+    return;
+
+  dfreq = (freq - prev_freq) / (1.0 - prev_freq);
+  elapsed = UTI_DiffTimespecsToDouble(&ref_time, prev_ref_time);
+  doffset = offset - elapsed * prev_freq - prev_offset;
+
+  if (!REF_AdjustReference(doffset, dfreq))
+    return;
+
+  LCL_ReadCookedTime(&now, NULL);
+  SST_SlewSamples(stats, &now, dfreq, doffset);
+  SPF_SlewSamples(inst->filter, &now, dfreq, doffset);
+
+  /* Keep the offset close to zero to not lose precision */
+  if (fabs(offset) >= 1.0) {
+    SST_CorrectOffset(stats, -round(offset));
+    SPF_CorrectOffset(inst->filter, -round(offset));
+  }
+}
+
+static void
+poll_timeout(void *arg)
+{
+  NTP_Sample sample;
+  int poll, stratum;
+
+  RCL_Instance inst = (RCL_Instance)arg;
+
+  poll = inst->poll;
+
+  if (inst->driver->poll) {
+    poll = inst->driver_poll;
+    inst->driver->poll(inst);
+    inst->driver_polled++;
+  }
+  
+  if (!(inst->driver->poll && inst->driver_polled < (1 << (inst->poll - inst->driver_poll)))) {
+    inst->driver_polled = 0;
+
+    if (SPF_GetFilteredSample(inst->filter, &sample)) {
+      double local_freq, local_offset;
+      struct timespec local_ref_time;
+
+      /* Handle special case when PPS is used with the local reference */
+      if (inst->pps_active && inst->lock_ref == -1)
+        stratum = pps_stratum(inst, &sample.time);
+      else
+        stratum = inst->stratum;
+
+      if (inst->local) {
+        get_local_stats(inst, &local_ref_time, &local_freq, &local_offset);
+        inst->leap_status = LEAP_Unsynchronised;
+      }
+
+      SRC_UpdateReachability(inst->source, 1);
+      SRC_UpdateStatus(inst->source, stratum, inst->leap_status);
+      SRC_AccumulateSample(inst->source, &sample);
+      SRC_SelectSource(inst->source);
+
+      if (inst->local)
+        follow_local(inst, &local_ref_time, local_freq, local_offset);
+
+      log_sample(inst, &sample.time, 1, 0, 0.0, sample.offset, sample.peer_dispersion);
+    } else {
+      SRC_UpdateReachability(inst->source, 0);
+    }
+  }
+
+  inst->timeout_id = SCH_AddTimeoutByDelay(UTI_Log2ToDouble(poll), poll_timeout, arg);
+}
+
+static void
+slew_samples(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++) {
+    if (change_type == LCL_ChangeUnknownStep)
+      SPF_DropSamples(get_refclock(i)->filter);
+    else
+      SPF_SlewSamples(get_refclock(i)->filter, cooked, dfreq, doffset);
+  }
+}
+
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  unsigned int i;
+
+  for (i = 0; i < ARR_GetSize(refclocks); i++)
+    SPF_AddDispersion(get_refclock(i)->filter, dispersion);
+}
+
+static void
+log_sample(RCL_Instance instance, struct timespec *sample_time, int filtered, int pulse, double raw_offset, double cooked_offset, double dispersion)
+{
+  char sync_stats[4] = {'N', '+', '-', '?'};
+
+  if (logfileid == -1)
+    return;
+
+  if (!filtered) {
+    LOG_FileWrite(logfileid, "%s.%06d %-5s %3d %1c %1d %13.6e %13.6e %10.3e",
+      UTI_TimeToLogForm(sample_time->tv_sec),
+      (int)sample_time->tv_nsec / 1000,
+      UTI_RefidToString(instance->ref_id),
+      instance->driver_polled,
+      sync_stats[instance->leap_status],
+      pulse,
+      raw_offset,
+      cooked_offset,
+      dispersion);
+  } else {
+    LOG_FileWrite(logfileid, "%s.%06d %-5s   - %1c -       -       %13.6e %10.3e",
+      UTI_TimeToLogForm(sample_time->tv_sec),
+      (int)sample_time->tv_nsec / 1000,
+      UTI_RefidToString(instance->ref_id),
+      sync_stats[instance->leap_status],
+      cooked_offset,
+      dispersion);
+  }
+}
diff --git a/refclock.h b/refclock.h
new file mode 100644
index 0000000..7947b62
--- /dev/null
+++ b/refclock.h
@@ -0,0 +1,86 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for refclocks.
+
+  */
+
+#ifndef GOT_REFCLOCK_H
+#define GOT_REFCLOCK_H
+
+#include "srcparams.h"
+#include "sources.h"
+
+typedef struct {
+  char *driver_name;
+  char *driver_parameter;
+  int driver_poll;
+  int poll;
+  int filter_length;
+  int local;
+  int pps_forced;
+  int pps_rate;
+  int min_samples;
+  int max_samples;
+  int sel_options;
+  int max_lock_age;
+  int stratum;
+  int tai;
+  uint32_t ref_id;
+  uint32_t lock_ref_id;
+  double offset;
+  double delay;
+  double precision;
+  double max_dispersion;
+  double pulse_width;
+} RefclockParameters;
+
+typedef struct RCL_Instance_Record *RCL_Instance;
+
+typedef struct {
+  int (*init)(RCL_Instance instance);
+  void (*fini)(RCL_Instance instance);
+  int (*poll)(RCL_Instance instance);
+} RefclockDriver;
+
+extern void RCL_Initialise(void);
+extern void RCL_Finalise(void);
+extern int RCL_AddRefclock(RefclockParameters *params);
+extern void RCL_StartRefclocks(void);
+extern void RCL_ReportSource(RPT_SourceReport *report, struct timespec *now);
+
+/* functions used by drivers */
+extern void RCL_SetDriverData(RCL_Instance instance, void *data);
+extern void *RCL_GetDriverData(RCL_Instance instance);
+extern char *RCL_GetDriverParameter(RCL_Instance instance);
+extern void RCL_CheckDriverOptions(RCL_Instance instance, const char **options);
+extern char *RCL_GetDriverOption(RCL_Instance instance, char *name);
+extern int RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+                         struct timespec *ref_time, int leap);
+extern int RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second);
+extern int RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
+                              double second, double dispersion, double raw_correction);
+extern double RCL_GetPrecision(RCL_Instance instance);
+extern int RCL_GetDriverPoll(RCL_Instance instance);
+
+#endif
diff --git a/refclock_phc.c b/refclock_phc.c
new file mode 100644
index 0000000..abda2e8
--- /dev/null
+++ b/refclock_phc.c
@@ -0,0 +1,232 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2013, 2017, 2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  PTP hardware clock (PHC) refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "refclock.h"
+
+#ifdef FEAT_PHC
+
+#include "sysincl.h"
+
+#include <sys/sysmacros.h>
+
+#include "array.h"
+#include "refclock.h"
+#include "hwclock.h"
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+#include "sched.h"
+#include "sys_linux.h"
+
+struct phc_instance {
+  int fd;
+  int dev_index;
+  int mode;
+  int nocrossts;
+  int extpps;
+  int pin;
+  int channel;
+  struct timespec last_extts;
+  HCL_Instance clock;
+};
+
+/* Array of RCL_Instance with enabled extpps */
+static ARR_Instance extts_phcs = NULL;
+
+static void read_ext_pulse(int sockfd, int event, void *anything);
+
+static int phc_initialise(RCL_Instance instance)
+{
+  const char *options[] = {"nocrossts", "extpps", "pin", "channel", "clear", NULL};
+  struct phc_instance *phc;
+  int phc_fd, rising_edge;
+  struct stat st;
+  char *path, *s;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  path = RCL_GetDriverParameter(instance);
+ 
+  phc_fd = SYS_Linux_OpenPHC(path, 0);
+  if (phc_fd < 0)
+    LOG_FATAL("Could not open PHC");
+
+  phc = MallocNew(struct phc_instance);
+  phc->fd = phc_fd;
+  if (fstat(phc_fd, &st) < 0 || !S_ISCHR(st.st_mode))
+    LOG_FATAL("Could not get PHC index");
+  phc->dev_index = minor(st.st_rdev);
+  phc->mode = 0;
+  phc->nocrossts = RCL_GetDriverOption(instance, "nocrossts") ? 1 : 0;
+  phc->extpps = RCL_GetDriverOption(instance, "extpps") ? 1 : 0;
+  UTI_ZeroTimespec(&phc->last_extts);
+  phc->clock = HCL_CreateInstance(0, 16, UTI_Log2ToDouble(RCL_GetDriverPoll(instance)),
+                                  RCL_GetPrecision(instance));
+
+  if (phc->extpps) {
+    s = RCL_GetDriverOption(instance, "pin");
+    phc->pin = s ? atoi(s) : 0;
+    s = RCL_GetDriverOption(instance, "channel");
+    phc->channel = s ? atoi(s) : 0;
+    rising_edge = RCL_GetDriverOption(instance, "clear") ? 0 : 1;
+
+    if (!SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel,
+                                         rising_edge, !rising_edge, 1))
+      LOG_FATAL("Could not enable external PHC timestamping");
+
+    SCH_AddFileHandler(phc->fd, SCH_FILE_INPUT, read_ext_pulse, instance);
+
+    if (!extts_phcs)
+      extts_phcs = ARR_CreateInstance(sizeof (RCL_Instance));
+    ARR_AppendElement(extts_phcs, &instance);
+  } else {
+    phc->pin = phc->channel = 0;
+  }
+
+  RCL_SetDriverData(instance, phc);
+  return 1;
+}
+
+static void phc_finalise(RCL_Instance instance)
+{
+  struct phc_instance *phc;
+  unsigned int i;
+
+  phc = (struct phc_instance *)RCL_GetDriverData(instance);
+
+  if (phc->extpps) {
+    SCH_RemoveFileHandler(phc->fd);
+    SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel, 0, 0, 0);
+
+    for (i = 0; i < ARR_GetSize(extts_phcs); i++) {
+      if ((*(RCL_Instance *)ARR_GetElement(extts_phcs, i)) == instance)
+        ARR_RemoveElement(extts_phcs, i--);
+    }
+    if (ARR_GetSize(extts_phcs) == 0) {
+      ARR_DestroyInstance(extts_phcs);
+      extts_phcs = NULL;
+    }
+  }
+
+  HCL_DestroyInstance(phc->clock);
+  close(phc->fd);
+  Free(phc);
+}
+
+static void process_ext_pulse(RCL_Instance instance, struct timespec *phc_ts)
+{
+  struct phc_instance *phc;
+  struct timespec local_ts;
+  double local_err;
+
+  phc = RCL_GetDriverData(instance);
+
+  if (UTI_CompareTimespecs(&phc->last_extts, phc_ts) == 0) {
+    DEBUG_LOG("Ignoring duplicated PHC timestamp");
+    return;
+  }
+  phc->last_extts = *phc_ts;
+
+  if (!HCL_CookTime(phc->clock, phc_ts, &local_ts, &local_err))
+    return;
+
+  RCL_AddCookedPulse(instance, &local_ts, 1.0e-9 * local_ts.tv_nsec, local_err,
+                     UTI_DiffTimespecsToDouble(phc_ts, &local_ts));
+}
+
+static void read_ext_pulse(int fd, int event, void *anything)
+{
+  RCL_Instance instance;
+  struct phc_instance *phc1, *phc2;
+  struct timespec phc_ts;
+  unsigned int i;
+  int channel;
+
+  if (!SYS_Linux_ReadPHCExtTimestamp(fd, &phc_ts, &channel))
+    return;
+
+  instance = anything;
+  phc1 = RCL_GetDriverData(instance);
+
+  /* The Linux kernel (as of 6.2) has one shared queue of timestamps for all
+     descriptors of the same PHC.  Search for all refclocks that expect
+     the timestamp. */
+
+  for (i = 0; i < ARR_GetSize(extts_phcs); i++) {
+    instance = *(RCL_Instance *)ARR_GetElement(extts_phcs, i);
+    phc2 = RCL_GetDriverData(instance);
+    if (!phc2->extpps || phc2->dev_index != phc1->dev_index || phc2->channel != channel)
+      continue;
+    process_ext_pulse(instance, &phc_ts);
+  }
+}
+
+#define PHC_READINGS 25
+
+static int phc_poll(RCL_Instance instance)
+{
+  struct timespec phc_ts, sys_ts, local_ts, readings[PHC_READINGS][3];
+  struct phc_instance *phc;
+  double phc_err, local_err;
+  int n_readings;
+
+  phc = (struct phc_instance *)RCL_GetDriverData(instance);
+
+  n_readings = SYS_Linux_GetPHCReadings(phc->fd, phc->nocrossts, &phc->mode,
+                                        PHC_READINGS, readings);
+  if (n_readings < 1)
+    return 0;
+
+  if (!HCL_ProcessReadings(phc->clock, n_readings, readings, &phc_ts, &sys_ts, &phc_err))
+    return 0;
+
+  LCL_CookTime(&sys_ts, &local_ts, &local_err);
+  HCL_AccumulateSample(phc->clock, &phc_ts, &local_ts, phc_err + local_err);
+
+  if (phc->extpps)
+    return 0;
+
+  DEBUG_LOG("PHC offset: %+.9f err: %.9f",
+            UTI_DiffTimespecsToDouble(&phc_ts, &sys_ts), phc_err);
+
+  return RCL_AddSample(instance, &sys_ts, &phc_ts, LEAP_Normal);
+}
+
+RefclockDriver RCL_PHC_driver = {
+  phc_initialise,
+  phc_finalise,
+  phc_poll
+};
+
+#else
+
+RefclockDriver RCL_PHC_driver = { NULL, NULL, NULL };
+
+#endif
diff --git a/refclock_pps.c b/refclock_pps.c
new file mode 100644
index 0000000..880c13f
--- /dev/null
+++ b/refclock_pps.c
@@ -0,0 +1,159 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  PPSAPI refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "refclock.h"
+
+#if FEAT_PPS
+
+#if defined(HAVE_SYS_TIMEPPS_H)
+#include <sys/timepps.h>
+#elif defined(HAVE_TIMEPPS_H)
+#include <timepps.h>
+#endif
+
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+
+struct pps_instance {
+  pps_handle_t handle;
+  pps_seq_t last_seq;
+  int edge_clear;
+};
+
+static int pps_initialise(RCL_Instance instance) {
+  const char *options[] = {"clear", NULL};
+  pps_handle_t handle;
+  pps_params_t params;
+  struct pps_instance *pps;
+  int fd, edge_clear, mode;
+  char *path;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  path = RCL_GetDriverParameter(instance);
+  edge_clear = RCL_GetDriverOption(instance, "clear") ? 1 : 0;
+
+  fd = open(path, O_RDWR);
+  if (fd < 0)
+    LOG_FATAL("Could not open %s : %s", path, strerror(errno));
+
+  UTI_FdSetCloexec(fd);
+
+  if (time_pps_create(fd, &handle) < 0)
+    LOG_FATAL("time_pps_create() failed on %s : %s", path, strerror(errno));
+
+  if (time_pps_getcap(handle, &mode) < 0)
+    LOG_FATAL("time_pps_getcap() failed on %s : %s", path, strerror(errno));
+
+  if (time_pps_getparams(handle, &params) < 0)
+    LOG_FATAL("time_pps_getparams() failed on %s : %s", path, strerror(errno));
+
+  if (!edge_clear) {
+    if (!(mode & PPS_CAPTUREASSERT))
+      LOG_FATAL("CAPTUREASSERT not supported on %s", path);
+
+    params.mode |= PPS_CAPTUREASSERT;
+    params.mode &= ~PPS_CAPTURECLEAR;
+  } else {
+    if (!(mode & PPS_CAPTURECLEAR))
+      LOG_FATAL("CAPTURECLEAR not supported on %s", path);
+
+    params.mode |= PPS_CAPTURECLEAR;
+    params.mode &= ~PPS_CAPTUREASSERT;
+  }
+
+  if (time_pps_setparams(handle, &params) < 0)
+    LOG_FATAL("time_pps_setparams() failed on %s : %s", path, strerror(errno));
+
+  pps = MallocNew(struct pps_instance);
+  pps->handle = handle;
+  pps->last_seq = 0;
+  pps->edge_clear = edge_clear;
+
+  RCL_SetDriverData(instance, pps);
+  return 1;
+}
+
+static void pps_finalise(RCL_Instance instance)
+{
+  struct pps_instance *pps; 
+
+  pps = (struct pps_instance *)RCL_GetDriverData(instance);
+  time_pps_destroy(pps->handle);
+  Free(pps);
+}
+
+static int pps_poll(RCL_Instance instance)
+{
+  struct pps_instance *pps; 
+  struct timespec ts;
+  pps_info_t pps_info;
+  pps_seq_t seq;
+
+  pps = (struct pps_instance *)RCL_GetDriverData(instance);
+
+  ts.tv_sec = 0;
+  ts.tv_nsec = 0;
+
+  if (time_pps_fetch(pps->handle, PPS_TSFMT_TSPEC, &pps_info, &ts) < 0) {
+    LOG(LOGS_ERR, "time_pps_fetch() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  if (!pps->edge_clear) {
+    seq = pps_info.assert_sequence;
+    ts = pps_info.assert_timestamp;
+  } else {
+    seq = pps_info.clear_sequence;
+    ts = pps_info.clear_timestamp;
+  }
+
+  if (seq == pps->last_seq || UTI_IsZeroTimespec(&ts)) {
+    DEBUG_LOG("PPS sample ignored seq=%lu ts=%s",
+              (unsigned long)seq, UTI_TimespecToString(&ts));
+    return 0;
+  }
+
+  pps->last_seq = seq;
+
+  return RCL_AddPulse(instance, &ts, 1.0e-9 * ts.tv_nsec);
+}
+
+RefclockDriver RCL_PPS_driver = {
+  pps_initialise,
+  pps_finalise,
+  pps_poll
+};
+
+#else
+
+RefclockDriver RCL_PPS_driver = { NULL, NULL, NULL };
+
+#endif
diff --git a/refclock_shm.c b/refclock_shm.c
new file mode 100644
index 0000000..ee13e87
--- /dev/null
+++ b/refclock_shm.c
@@ -0,0 +1,134 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  SHM refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "refclock.h"
+#include "logging.h"
+#include "util.h"
+
+#define SHMKEY 0x4e545030
+
+struct shmTime {
+  int    mode; /* 0 - if valid set
+                *       use values, 
+                *       clear valid
+                * 1 - if valid set 
+                *       if count before and after read of values is equal,
+                *         use values 
+                *       clear valid
+                */
+  volatile int count;
+  time_t clockTimeStampSec;
+  int    clockTimeStampUSec;
+  time_t receiveTimeStampSec;
+  int    receiveTimeStampUSec;
+  int    leap;
+  int    precision;
+  int    nsamples;
+  volatile int valid;
+  int    clockTimeStampNSec;
+  int    receiveTimeStampNSec;
+  int    dummy[8]; 
+};
+
+static int shm_initialise(RCL_Instance instance) {
+  const char *options[] = {"perm", NULL};
+  int id, param, perm;
+  char *s;
+  struct shmTime *shm;
+
+  RCL_CheckDriverOptions(instance, options);
+
+  param = atoi(RCL_GetDriverParameter(instance));
+  s = RCL_GetDriverOption(instance, "perm");
+  perm = s ? strtol(s, NULL, 8) & 0777 : 0600;
+
+  id = shmget(SHMKEY + param, sizeof (struct shmTime), IPC_CREAT | perm);
+  if (id == -1) {
+    LOG_FATAL("shmget() failed : %s", strerror(errno));
+    return 0;
+  }
+   
+  shm = (struct shmTime *)shmat(id, 0, 0);
+  if ((long)shm == -1) {
+    LOG_FATAL("shmat() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  RCL_SetDriverData(instance, shm);
+  return 1;
+}
+
+static void shm_finalise(RCL_Instance instance)
+{
+  shmdt(RCL_GetDriverData(instance));
+}
+
+static int shm_poll(RCL_Instance instance)
+{
+  struct timespec receive_ts, clock_ts;
+  struct shmTime t, *shm;
+
+  shm = (struct shmTime *)RCL_GetDriverData(instance);
+
+  t = *shm;
+  
+  if ((t.mode == 1 && t.count != shm->count) ||
+    !(t.mode == 0 || t.mode == 1) || !t.valid) {
+    DEBUG_LOG("SHM sample ignored mode=%d count=%d valid=%d",
+        t.mode, t.count, t.valid);
+    return 0;
+  }
+
+  shm->valid = 0;
+
+  receive_ts.tv_sec = t.receiveTimeStampSec;
+  clock_ts.tv_sec = t.clockTimeStampSec;
+
+  if (t.clockTimeStampNSec / 1000 == t.clockTimeStampUSec &&
+      t.receiveTimeStampNSec / 1000 == t.receiveTimeStampUSec) {
+    receive_ts.tv_nsec = t.receiveTimeStampNSec;
+    clock_ts.tv_nsec = t.clockTimeStampNSec;
+  } else {
+    receive_ts.tv_nsec = 1000 * t.receiveTimeStampUSec;
+    clock_ts.tv_nsec = 1000 * t.clockTimeStampUSec;
+  }
+
+  UTI_NormaliseTimespec(&clock_ts);
+  UTI_NormaliseTimespec(&receive_ts);
+
+  return RCL_AddSample(instance, &receive_ts, &clock_ts, t.leap);
+}
+
+RefclockDriver RCL_SHM_driver = {
+  shm_initialise,
+  shm_finalise,
+  shm_poll
+};
diff --git a/refclock_sock.c b/refclock_sock.c
new file mode 100644
index 0000000..2da57ef
--- /dev/null
+++ b/refclock_sock.c
@@ -0,0 +1,176 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Unix domain socket refclock driver.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "refclock.h"
+#include "logging.h"
+#include "util.h"
+#include "sched.h"
+#include "socket.h"
+
+#define SOCK_MAGIC 0x534f434b
+
+struct sock_sample {
+  /* Time of the measurement (system time) */
+  struct timeval tv;
+
+  /* Offset between the true time and the system time (in seconds) */
+  double offset;
+
+  /* Non-zero if the sample is from a PPS signal, i.e. another source
+     is needed to obtain seconds */
+  int pulse;
+
+  /* 0 - normal, 1 - insert leap second, 2 - delete leap second */
+  int leap;
+
+  /* Padding, ignored */
+  int _pad;
+
+  /* Protocol identifier (0x534f434b) */
+  int magic;
+};
+
+/* On 32-bit glibc-based systems enable conversion between timevals using
+   32-bit and 64-bit time_t to support SOCK clients compiled with different
+   time_t size than chrony */
+#ifdef __GLIBC_PREREQ
+#if __GLIBC_PREREQ(2, 34) && __TIMESIZE == 32
+#define CONVERT_TIMEVAL 1
+#if defined(_TIME_BITS) && _TIME_BITS == 64
+typedef int32_t alt_time_t;
+typedef int32_t alt_suseconds_t;
+#else
+typedef int64_t alt_time_t;
+typedef int64_t alt_suseconds_t;
+#endif
+struct alt_timeval {
+  alt_time_t tv_sec;
+  alt_suseconds_t tv_usec;
+};
+#endif
+#endif
+
+static void read_sample(int sockfd, int event, void *anything)
+{
+  char buf[sizeof (struct sock_sample) + 16];
+  struct timespec sys_ts, ref_ts;
+  struct sock_sample sample;
+  RCL_Instance instance;
+  int s;
+
+  instance = (RCL_Instance)anything;
+
+  s = recv(sockfd, buf, sizeof (buf), 0);
+
+  if (s < 0) {
+    DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
+    return;
+  }
+
+  if (s == sizeof (sample)) {
+    memcpy(&sample, buf, sizeof (sample));
+#ifdef CONVERT_TIMEVAL
+  } else if (s == sizeof (sample) - sizeof (struct timeval) + sizeof (struct alt_timeval)) {
+    struct alt_timeval atv;
+    memcpy(&atv, buf, sizeof (atv));
+#ifndef HAVE_LONG_TIME_T
+    if (atv.tv_sec > INT32_MAX || atv.tv_sec < INT32_MIN ||
+        atv.tv_usec > INT32_MAX || atv.tv_usec < INT32_MIN) {
+      DEBUG_LOG("Could not convert 64-bit timeval");
+      return;
+    }
+#endif
+    sample.tv.tv_sec = atv.tv_sec;
+    sample.tv.tv_usec = atv.tv_usec;
+    DEBUG_LOG("Converted %d-bit timeval", 8 * (int)sizeof (alt_time_t));
+    memcpy((char *)&sample + sizeof (struct timeval), buf + sizeof (struct alt_timeval),
+           sizeof (sample) - sizeof (struct timeval));
+#endif
+  } else {
+    DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
+              s, (long)sizeof (sample));
+    return;
+  }
+
+  if (sample.magic != SOCK_MAGIC) {
+    DEBUG_LOG("Unexpected magic number in SOCK sample : %x != %x",
+              (unsigned int)sample.magic, (unsigned int)SOCK_MAGIC);
+    return;
+  }
+
+  UTI_TimevalToTimespec(&sample.tv, &sys_ts);
+  UTI_NormaliseTimespec(&sys_ts);
+
+  if (!UTI_IsTimeOffsetSane(&sys_ts, sample.offset))
+    return;
+
+  UTI_AddDoubleToTimespec(&sys_ts, sample.offset, &ref_ts);
+
+  if (sample.pulse) {
+    RCL_AddPulse(instance, &sys_ts, sample.offset);
+  } else {
+    RCL_AddSample(instance, &sys_ts, &ref_ts, sample.leap);
+  }
+}
+
+static int sock_initialise(RCL_Instance instance)
+{
+  int sockfd;
+  char *path;
+
+  RCL_CheckDriverOptions(instance, NULL);
+
+  path = RCL_GetDriverParameter(instance);
+ 
+  sockfd = SCK_OpenUnixDatagramSocket(NULL, path, 0);
+  if (sockfd < 0)
+    LOG_FATAL("Could not open socket %s", path);
+
+  RCL_SetDriverData(instance, (void *)(long)sockfd);
+  SCH_AddFileHandler(sockfd, SCH_FILE_INPUT, read_sample, instance);
+  return 1;
+}
+
+static void sock_finalise(RCL_Instance instance)
+{
+  int sockfd;
+
+  sockfd = (long)RCL_GetDriverData(instance);
+  SCH_RemoveFileHandler(sockfd);
+  SCK_RemoveSocket(sockfd);
+  SCK_CloseSocket(sockfd);
+}
+
+RefclockDriver RCL_SOCK_driver = {
+  sock_initialise,
+  sock_finalise,
+  NULL
+};
diff --git a/reference.c b/reference.c
new file mode 100644
index 0000000..97dfbe9
--- /dev/null
+++ b/reference.c
@@ -0,0 +1,1441 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2018, 2020, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module keeps track of the source which we are claiming to be
+  our reference, for the purposes of generating outgoing NTP packets */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "memory.h"
+#include "reference.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "local.h"
+#include "sched.h"
+
+/* ================================================== */
+
+/* The minimum allowed skew */
+#define MIN_SKEW 1.0e-12
+
+/* The update interval of the reference in the local reference mode */
+#define LOCAL_REF_UPDATE_INTERVAL 64.0
+
+/* Interval between updates of the drift file */
+#define MAX_DRIFTFILE_AGE 3600.0
+
+static int are_we_synchronised;
+static int enable_local_stratum;
+static int local_stratum;
+static int local_orphan;
+static double local_distance;
+static struct timespec local_ref_time;
+static NTP_Leap our_leap_status;
+static int our_leap_sec;
+static int our_tai_offset;
+static int our_stratum;
+static uint32_t our_ref_id;
+static IPAddr our_ref_ip;
+static struct timespec our_ref_time;
+static double our_skew;
+static double our_residual_freq;
+static double our_root_delay;
+static double our_root_dispersion;
+static double our_offset_sd;
+static double our_frequency_sd;
+
+static double max_update_skew;
+
+static double last_offset;
+static double avg2_offset;
+static int avg2_moving;
+
+static double correction_time_ratio;
+
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* Current operating mode */
+static REF_Mode mode;
+
+/* Threshold and update limit for stepping clock */
+static int make_step_limit;
+static double make_step_threshold;
+
+/* Number of updates before offset checking, number of ignored updates
+   before exiting and the maximum allowed offset */
+static int max_offset_delay;
+static int max_offset_ignore;
+static double max_offset;
+
+/* Threshold for logging clock changes to syslog */
+static double log_change_threshold;
+
+/* Flag, threshold and user for sending mail notification on large clock changes */
+static int do_mail_change;
+static double mail_change_threshold;
+static char *mail_change_user;
+
+/* Handler for mode ending */
+static REF_ModeEndHandler mode_end_handler = NULL;
+
+/* Filename of the drift file. */
+static char *drift_file=NULL;
+static double drift_file_age;
+
+static void update_drift_file(double, double);
+
+/* Leap second handling mode */
+static REF_LeapMode leap_mode;
+
+/* Time of UTC midnight of the upcoming or previous leap second */
+static time_t leap_when;
+
+/* Flag indicating the clock was recently corrected for leap second and it may
+   not have correct time yet (missing 23:59:60 in the UTC time scale) */
+static int leap_in_progress;
+
+/* Timer for the leap second handler */
+static SCH_TimeoutID leap_timeout_id;
+
+/* Name of a system timezone containing leap seconds occuring at midnight */
+static char *leap_tzname;
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+
+/* Exponential moving averages of absolute clock frequencies
+   used as a fallback when synchronisation is lost. */
+
+struct fb_drift {
+  double freq;
+  double secs;
+};
+
+static int fb_drift_min;
+static int fb_drift_max;
+
+static struct fb_drift *fb_drifts = NULL;
+static int next_fb_drift;
+static SCH_TimeoutID fb_drift_timeout_id;
+
+/* Monotonic timestamp of the last reference update */
+static double last_ref_update;
+static double last_ref_update_interval;
+
+static double last_ref_adjustment;
+static int ref_adjustments;
+
+/* ================================================== */
+
+static NTP_Leap get_tz_leap(time_t when, int *tai_offset);
+static void update_leap_status(NTP_Leap leap, time_t now, int reset);
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything)
+{
+  double delta;
+  struct timespec now;
+
+  if (!UTI_IsZeroTimespec(&our_ref_time))
+    UTI_AdjustTimespec(&our_ref_time, cooked, &our_ref_time, &delta, dfreq, doffset);
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    last_ref_update = 0.0;
+    REF_SetUnsynchronised();
+  }
+
+  /* When the clock was stepped, check if that doesn't change our leap status
+     and also reset the leap timeout to undo the shift in the scheduler */
+  if (change_type != LCL_ChangeAdjust && our_leap_sec && !leap_in_progress) {
+    LCL_ReadRawTime(&now);
+    update_leap_status(our_leap_status, now.tv_sec, 1);
+  }
+}
+
+/* ================================================== */
+
+void
+REF_Initialise(void)
+{
+  FILE *in;
+  double file_freq_ppm, file_skew_ppm;
+  double our_frequency_ppm;
+  int tai_offset;
+
+  mode = REF_ModeNormal;
+  are_we_synchronised = 0;
+  our_leap_status = LEAP_Unsynchronised;
+  our_leap_sec = 0;
+  our_tai_offset = 0;
+  initialised = 1;
+  our_root_dispersion = 1.0;
+  our_root_delay = 1.0;
+  our_frequency_ppm = 0.0;
+  our_skew = 1.0; /* i.e. rather bad */
+  our_residual_freq = 0.0;
+  our_frequency_sd = 0.0;
+  our_offset_sd = 0.0;
+  drift_file_age = 0.0;
+
+  /* Now see if we can get the drift file opened */
+  drift_file = CNF_GetDriftFile();
+  if (drift_file) {
+    in = UTI_OpenFile(NULL, drift_file, NULL, 'r', 0);
+    if (in) {
+      if (fscanf(in, "%lf%lf", &file_freq_ppm, &file_skew_ppm) == 2) {
+        /* We have read valid data */
+        our_frequency_ppm = file_freq_ppm;
+        our_skew = 1.0e-6 * file_skew_ppm;
+        if (our_skew < MIN_SKEW)
+          our_skew = MIN_SKEW;
+        LOG(LOGS_INFO, "Frequency %.3f +/- %.3f ppm read from %s",
+            file_freq_ppm, file_skew_ppm, drift_file);
+        LCL_SetAbsoluteFrequency(our_frequency_ppm);
+      } else {
+        LOG(LOGS_WARN, "Could not read valid frequency and skew from driftfile %s",
+            drift_file);
+      }
+      fclose(in);
+    }
+  }
+    
+  if (our_frequency_ppm == 0.0) {
+    our_frequency_ppm = LCL_ReadAbsoluteFrequency();
+    if (our_frequency_ppm != 0.0) {
+      LOG(LOGS_INFO, "Initial frequency %.3f ppm", our_frequency_ppm);
+    }
+  }
+
+  logfileid = CNF_GetLogTracking() ? LOG_FileOpen("tracking",
+      "   Date (UTC) Time     IP Address   St   Freq ppm   Skew ppm     Offset L Co  Offset sd Rem. corr. Root delay Root disp. Max. error")
+    : -1;
+
+  max_update_skew = fabs(CNF_GetMaxUpdateSkew()) * 1.0e-6;
+
+  correction_time_ratio = CNF_GetCorrectionTimeRatio();
+
+  enable_local_stratum = CNF_AllowLocalReference(&local_stratum, &local_orphan, &local_distance);
+  UTI_ZeroTimespec(&local_ref_time);
+
+  leap_when = 0;
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+  leap_mode = CNF_GetLeapSecMode();
+  /* Switch to step mode if the system driver doesn't support leap */
+  if (leap_mode == REF_LeapModeSystem && !LCL_CanSystemLeap())
+    leap_mode = REF_LeapModeStep;
+
+  leap_tzname = CNF_GetLeapSecTimezone();
+  if (leap_tzname) {
+    /* Check that the timezone has good data for Jun 30 2012 and Dec 31 2012 */
+    if (get_tz_leap(1341014400, &tai_offset) == LEAP_InsertSecond && tai_offset == 34 &&
+        get_tz_leap(1356912000, &tai_offset) == LEAP_Normal && tai_offset == 35) {
+      LOG(LOGS_INFO, "Using %s timezone to obtain leap second data", leap_tzname);
+    } else {
+      LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring", leap_tzname);
+      leap_tzname = NULL;
+    }
+  }
+
+  CNF_GetMakeStep(&make_step_limit, &make_step_threshold);
+  CNF_GetMaxChange(&max_offset_delay, &max_offset_ignore, &max_offset);
+  CNF_GetMailOnChange(&do_mail_change, &mail_change_threshold, &mail_change_user);
+  log_change_threshold = CNF_GetLogChange();
+
+  CNF_GetFallbackDrifts(&fb_drift_min, &fb_drift_max);
+
+  if (fb_drift_max >= fb_drift_min && fb_drift_min > 0) {
+    fb_drifts = MallocArray(struct fb_drift, fb_drift_max - fb_drift_min + 1);
+    memset(fb_drifts, 0, sizeof (struct fb_drift) * (fb_drift_max - fb_drift_min + 1));
+    next_fb_drift = 0;
+    fb_drift_timeout_id = 0;
+  }
+
+  UTI_ZeroTimespec(&our_ref_time);
+  last_ref_update = 0.0;
+  last_ref_update_interval = 0.0;
+  last_ref_adjustment = 0.0;
+  ref_adjustments = 0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+
+  /* Make first entry in tracking log */
+  REF_SetUnsynchronised();
+}
+
+/* ================================================== */
+
+void
+REF_Finalise(void)
+{
+  update_leap_status(LEAP_Unsynchronised, 0, 0);
+
+  if (drift_file) {
+    update_drift_file(LCL_ReadAbsoluteFrequency(), our_skew);
+  }
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  Free(fb_drifts);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void REF_SetMode(REF_Mode new_mode)
+{
+  mode = new_mode;
+}
+
+/* ================================================== */
+
+REF_Mode
+REF_GetMode(void)
+{
+  return mode;
+}
+
+/* ================================================== */
+
+void
+REF_SetModeEndHandler(REF_ModeEndHandler handler)
+{
+  mode_end_handler = handler;
+}
+
+/* ================================================== */
+
+REF_LeapMode
+REF_GetLeapMode(void)
+{
+  return leap_mode;
+}
+
+/* ================================================== */
+/* Update the drift coefficients to the file. */
+
+static void
+update_drift_file(double freq_ppm, double skew)
+{
+  FILE *out;
+
+  /* Create a temporary file with a '.tmp' extension. */
+  out = UTI_OpenFile(NULL, drift_file, ".tmp", 'w', 0644);
+  if (!out)
+    return;
+
+  /* Write the frequency and skew parameters in ppm */
+  fprintf(out, "%20.6f %20.6f\n", freq_ppm, 1.0e6 * skew);
+  fclose(out);
+
+  /* Rename the temporary file to the correct location */
+  if (!UTI_RenameTempFile(NULL, drift_file, ".tmp", NULL))
+    ;
+}
+
+/* ================================================== */
+
+static void
+update_fb_drifts(double freq_ppm, double update_interval)
+{
+  int i, secs;
+
+  assert(are_we_synchronised);
+
+  if (next_fb_drift > 0) {
+#if 0
+    /* Reset drifts that were used when we were unsynchronised */
+    for (i = 0; i < next_fb_drift - fb_drift_min; i++)
+      fb_drifts[i].secs = 0.0;
+#endif
+    next_fb_drift = 0;
+  }
+
+  SCH_RemoveTimeout(fb_drift_timeout_id);
+  fb_drift_timeout_id = 0;
+
+  if (update_interval < 1.0 || update_interval > last_ref_update_interval * 4.0)
+    return;
+
+  for (i = 0; i < fb_drift_max - fb_drift_min + 1; i++) {
+    secs = 1 << (i + fb_drift_min);
+    if (fb_drifts[i].secs < secs) {
+      /* Calculate average over 2 * secs interval before switching to
+         exponential updating */
+      fb_drifts[i].freq = (fb_drifts[i].freq * fb_drifts[i].secs +
+          update_interval * 0.5 * freq_ppm) / (update_interval * 0.5 + fb_drifts[i].secs);
+      fb_drifts[i].secs += update_interval * 0.5;
+    } else {
+      /* Update exponential moving average. The smoothing factor for update
+         interval equal to secs is about 0.63, for half interval about 0.39,
+         for double interval about 0.86. */
+      fb_drifts[i].freq += (1 - 1.0 / exp(update_interval / secs)) *
+        (freq_ppm - fb_drifts[i].freq);
+    }
+
+    DEBUG_LOG("Fallback drift %d updated: %f ppm %f seconds",
+              i + fb_drift_min, fb_drifts[i].freq, fb_drifts[i].secs);
+  }
+}
+
+/* ================================================== */
+
+static void
+fb_drift_timeout(void *arg)
+{
+  assert(next_fb_drift >= fb_drift_min && next_fb_drift <= fb_drift_max);
+
+  fb_drift_timeout_id = 0;
+
+  DEBUG_LOG("Fallback drift %d active: %f ppm",
+            next_fb_drift, fb_drifts[next_fb_drift - fb_drift_min].freq);
+  LCL_SetAbsoluteFrequency(fb_drifts[next_fb_drift - fb_drift_min].freq);
+  REF_SetUnsynchronised();
+}
+
+/* ================================================== */
+
+static void
+schedule_fb_drift(void)
+{
+  int i, c, secs;
+  double unsynchronised, now;
+
+  if (fb_drift_timeout_id)
+    return; /* already scheduled */
+
+  now = SCH_GetLastEventMonoTime();
+  unsynchronised = now - last_ref_update;
+
+  for (c = secs = 0, i = fb_drift_min; i <= fb_drift_max; i++) {
+    secs = 1 << i;
+
+    if (fb_drifts[i - fb_drift_min].secs < secs)
+      continue;
+
+    if (unsynchronised < secs && i > next_fb_drift)
+      break;
+
+    c = i;
+  }
+
+  if (c > next_fb_drift) {
+    LCL_SetAbsoluteFrequency(fb_drifts[c - fb_drift_min].freq);
+    next_fb_drift = c;
+    DEBUG_LOG("Fallback drift %d set", c);
+  }
+
+  if (i <= fb_drift_max) {
+    next_fb_drift = i;
+    fb_drift_timeout_id = SCH_AddTimeoutByDelay(secs - unsynchronised, fb_drift_timeout, NULL);
+    DEBUG_LOG("Fallback drift %d scheduled", i);
+  }
+}
+
+/* ================================================== */
+
+static void
+end_ref_mode(int result)
+{
+  mode = REF_ModeIgnore;
+
+  /* Dispatch the handler */
+  if (mode_end_handler)
+    (mode_end_handler)(result);
+}
+
+/* ================================================== */
+
+#define BUFLEN 255
+#define S_MAX_USER_LEN "128"
+
+static void
+maybe_log_offset(double offset, time_t now)
+{
+  double abs_offset;
+  FILE *p;
+  char buffer[BUFLEN], host[BUFLEN];
+  struct tm *tm;
+
+  abs_offset = fabs(offset);
+
+  if (abs_offset > log_change_threshold) {
+    LOG(LOGS_WARN, "System clock wrong by %.6f seconds", -offset);
+  }
+
+  if (do_mail_change &&
+      (abs_offset > mail_change_threshold)) {
+    snprintf(buffer, sizeof (buffer), "%s -t", MAIL_PROGRAM);
+    p = popen(buffer, "w");
+    if (p) {
+      if (gethostname(host, sizeof(host)) < 0) {
+        strcpy(host, "<UNKNOWN>");
+      }
+      host[sizeof (host) - 1] = '\0';
+
+      fprintf(p, "To: %s\n", mail_change_user);
+      fprintf(p, "Subject: chronyd reports change to system clock on node [%s]\n", host);
+      fputs("\n", p);
+
+      tm = localtime(&now);
+      if (tm) {
+        strftime(buffer, sizeof (buffer),
+                 "On %A, %d %B %Y\n  with the system clock reading %H:%M:%S (%Z)", tm);
+        fputs(buffer, p);
+      }
+
+      /* If offset < 0 the local clock is slow, so we are applying a
+         positive change to it to bring it into line, hence the
+         negation of 'offset' in the next statement (and earlier) */
+      fprintf(p,
+              "\n\nchronyd started to apply an adjustment of %.3f seconds to it,\n"
+              "  which exceeded the reporting threshold of %.3f seconds\n\n",
+              -offset, mail_change_threshold);
+      pclose(p);
+    } else {
+      LOG(LOGS_ERR, "Could not send mail notification to user %s\n",
+          mail_change_user);
+    }
+  }
+
+}
+
+/* ================================================== */
+
+static int
+is_step_limit_reached(double offset, double offset_correction)
+{
+  if (make_step_limit == 0) {
+    return 0;
+  } else if (make_step_limit > 0) {
+    make_step_limit--;
+  }
+  return fabs(offset - offset_correction) > make_step_threshold;
+}
+
+/* ================================================== */
+
+static int
+is_offset_ok(double offset)
+{
+  if (max_offset_delay < 0)
+    return 1;
+
+  if (max_offset_delay > 0) {
+    max_offset_delay--;
+    return 1;
+  }
+
+  if (fabs(offset) > max_offset) {
+    LOG(LOGS_WARN, 
+        "Adjustment of %.3f seconds exceeds the allowed maximum of %.3f seconds (%s) ",
+        -offset, max_offset, !max_offset_ignore ? "exiting" : "ignored");
+    if (!max_offset_ignore)
+      end_ref_mode(0);
+    else if (max_offset_ignore > 0)
+      max_offset_ignore--;
+    return 0;
+  }
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+is_leap_second_day(time_t when)
+{
+  struct tm *stm;
+
+  stm = gmtime(&when);
+  if (!stm)
+    return 0;
+
+  /* Allow leap second only on the last day of June and December */
+  return (stm->tm_mon == 5 && stm->tm_mday == 30) ||
+         (stm->tm_mon == 11 && stm->tm_mday == 31);
+}
+
+/* ================================================== */
+
+static NTP_Leap
+get_tz_leap(time_t when, int *tai_offset)
+{
+  static time_t last_tz_leap_check;
+  static NTP_Leap tz_leap;
+  static int tz_tai_offset;
+
+  struct tm stm, *tm;
+  time_t t;
+  char *tz_env, tz_orig[128];
+
+  *tai_offset = tz_tai_offset;
+
+  /* Do this check at most twice a day */
+  when = when / (12 * 3600) * (12 * 3600);
+  if (last_tz_leap_check == when)
+      return tz_leap;
+
+  last_tz_leap_check = when;
+  tz_leap = LEAP_Normal;
+  tz_tai_offset = 0;
+
+  tm = gmtime(&when);
+  if (!tm)
+    return tz_leap;
+
+  stm = *tm;
+
+  /* Temporarily switch to the timezone containing leap seconds */
+  tz_env = getenv("TZ");
+  if (tz_env) {
+    if (strlen(tz_env) >= sizeof (tz_orig))
+      return tz_leap;
+    strcpy(tz_orig, tz_env);
+  }
+  setenv("TZ", leap_tzname, 1);
+  tzset();
+
+  /* Get the TAI-UTC offset, which started at the epoch at 10 seconds */
+  t = mktime(&stm);
+  if (t != -1)
+    tz_tai_offset = t - when + 10;
+
+  /* Set the time to 23:59:60 and see how it overflows in mktime() */
+  stm.tm_sec = 60;
+  stm.tm_min = 59;
+  stm.tm_hour = 23;
+
+  t = mktime(&stm);
+
+  if (tz_env)
+    setenv("TZ", tz_orig, 1);
+  else
+    unsetenv("TZ");
+  tzset();
+
+  if (t == -1)
+    return tz_leap;
+
+  if (stm.tm_sec == 60)
+    tz_leap = LEAP_InsertSecond;
+  else if (stm.tm_sec == 1)
+    tz_leap = LEAP_DeleteSecond;
+
+  *tai_offset = tz_tai_offset;
+
+  return tz_leap;
+}
+
+/* ================================================== */
+
+static void
+leap_end_timeout(void *arg)
+{
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+
+  if (our_tai_offset)
+    our_tai_offset += our_leap_sec;
+  our_leap_sec = 0;
+
+  if (leap_mode == REF_LeapModeSystem)
+    LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
+
+  if (our_leap_status == LEAP_InsertSecond ||
+      our_leap_status == LEAP_DeleteSecond)
+    our_leap_status = LEAP_Normal;
+}
+
+/* ================================================== */
+
+static void
+leap_start_timeout(void *arg)
+{
+  leap_in_progress = 1;
+
+  switch (leap_mode) {
+    case REF_LeapModeSystem:
+      DEBUG_LOG("Waiting for system clock leap second correction");
+      break;
+    case REF_LeapModeSlew:
+      LCL_NotifyLeap(our_leap_sec);
+      LCL_AccumulateOffset(our_leap_sec, 0.0);
+      LOG(LOGS_WARN, "Adjusting system clock for leap second");
+      break;
+    case REF_LeapModeStep:
+      LCL_NotifyLeap(our_leap_sec);
+      LCL_ApplyStepOffset(our_leap_sec);
+      LOG(LOGS_WARN, "System clock was stepped for leap second");
+      break;
+    case REF_LeapModeIgnore:
+      LOG(LOGS_WARN, "Ignoring leap second");
+      break;
+    default:
+      break;
+  }
+
+  /* Wait until the leap second is over with some extra room to be safe */
+  leap_timeout_id = SCH_AddTimeoutByDelay(2.0, leap_end_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+set_leap_timeout(time_t now)
+{
+  struct timespec when;
+
+  /* Stop old timer if there is one */
+  SCH_RemoveTimeout(leap_timeout_id);
+  leap_timeout_id = 0;
+  leap_in_progress = 0;
+
+  if (!our_leap_sec)
+    return;
+
+  leap_when = (now / (24 * 3600) + 1) * (24 * 3600);
+
+  /* Insert leap second at 0:00:00 UTC, delete at 23:59:59 UTC.  If the clock
+     will be corrected by the system, timeout slightly sooner to be sure it
+     will happen before the system correction. */
+  when.tv_sec = leap_when;
+  when.tv_nsec = 0;
+  if (our_leap_sec < 0)
+    when.tv_sec--;
+  if (leap_mode == REF_LeapModeSystem) {
+    when.tv_sec--;
+    when.tv_nsec = 500000000;
+  }
+
+  leap_timeout_id = SCH_AddTimeout(&when, leap_start_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+update_leap_status(NTP_Leap leap, time_t now, int reset)
+{
+  NTP_Leap tz_leap;
+  int leap_sec, tai_offset;
+
+  leap_sec = 0;
+  tai_offset = 0;
+
+  if (leap_tzname && now) {
+    tz_leap = get_tz_leap(now, &tai_offset);
+    if (leap == LEAP_Normal)
+      leap = tz_leap;
+  }
+
+  if (leap == LEAP_InsertSecond || leap == LEAP_DeleteSecond) {
+    /* Check that leap second is allowed today */
+
+    if (is_leap_second_day(now)) {
+      if (leap == LEAP_InsertSecond) {
+        leap_sec = 1;
+      } else {
+        leap_sec = -1;
+      }
+    } else {
+      leap = LEAP_Normal;
+    }
+  }
+  
+  if ((leap_sec != our_leap_sec || tai_offset != our_tai_offset)
+      && !REF_IsLeapSecondClose(NULL, 0.0)) {
+    our_leap_sec = leap_sec;
+    our_tai_offset = tai_offset;
+
+    switch (leap_mode) {
+      case REF_LeapModeSystem:
+        LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
+        /* Fall through */
+      case REF_LeapModeSlew:
+      case REF_LeapModeStep:
+      case REF_LeapModeIgnore:
+        set_leap_timeout(now);
+        break;
+      default:
+        assert(0);
+        break;
+    }
+  } else if (reset) {
+    set_leap_timeout(now);
+  }
+
+  our_leap_status = leap;
+}
+
+/* ================================================== */
+
+static double
+get_root_dispersion(struct timespec *ts)
+{
+  if (UTI_IsZeroTimespec(&our_ref_time))
+    return 1.0;
+
+  return our_root_dispersion +
+         fabs(UTI_DiffTimespecsToDouble(ts, &our_ref_time)) *
+         (our_skew + fabs(our_residual_freq) + LCL_GetMaxClockError());
+}
+
+/* ================================================== */
+
+static void
+update_sync_status(struct timespec *now)
+{
+  double elapsed;
+
+  elapsed = fabs(UTI_DiffTimespecsToDouble(now, &our_ref_time));
+
+  LCL_SetSyncStatus(are_we_synchronised,
+                    our_offset_sd + elapsed * our_frequency_sd,
+                    our_root_delay / 2.0 + get_root_dispersion(now));
+}
+
+/* ================================================== */
+
+static void
+write_log(struct timespec *now, int combined_sources, double freq,
+          double offset, double offset_sd, double uncorrected_offset,
+          double orig_root_distance)
+{
+  const char leap_codes[4] = {'N', '+', '-', '?'};
+  double root_dispersion, max_error;
+  static double last_sys_offset = 0.0;
+
+  if (logfileid == -1)
+    return;
+
+  max_error = orig_root_distance + fabs(last_sys_offset);
+  root_dispersion = get_root_dispersion(now);
+  last_sys_offset = offset - uncorrected_offset;
+
+  LOG_FileWrite(logfileid,
+                "%s %-15s %2d %10.3f %10.3f %10.3e %1c %2d %10.3e %10.3e %10.3e %10.3e %10.3e",
+                UTI_TimeToLogForm(now->tv_sec),
+                our_ref_ip.family != IPADDR_UNSPEC ?
+                  UTI_IPToString(&our_ref_ip) : UTI_RefidToString(our_ref_id),
+                our_stratum, freq, 1.0e6 * our_skew, offset,
+                leap_codes[our_leap_status], combined_sources, offset_sd,
+                uncorrected_offset, our_root_delay, root_dispersion, max_error);
+}
+
+/* ================================================== */
+
+static void
+special_mode_sync(int valid, double offset)
+{
+  int step;
+
+  switch (mode) {
+    case REF_ModeInitStepSlew:
+      if (!valid) {
+        LOG(LOGS_WARN, "No suitable source for initstepslew");
+        end_ref_mode(0);
+        break;
+      }
+
+      step = fabs(offset) >= CNF_GetInitStepThreshold();
+
+      LOG(LOGS_INFO, "System's initial offset : %.6f seconds %s of true (%s)",
+          fabs(offset), offset >= 0 ? "fast" : "slow", step ? "step" : "slew");
+
+      if (step)
+        LCL_ApplyStepOffset(offset);
+      else
+        LCL_AccumulateOffset(offset, 0.0);
+
+      end_ref_mode(1);
+
+      break;
+    case REF_ModeUpdateOnce:
+    case REF_ModePrintOnce:
+      if (!valid) {
+        LOG(LOGS_WARN, "No suitable source for synchronisation");
+        end_ref_mode(0);
+        break;
+      }
+
+      step = mode == REF_ModeUpdateOnce;
+
+      LOG(LOGS_INFO, "System clock wrong by %.6f seconds (%s)",
+          -offset, step ? "step" : "ignored");
+
+      if (step)
+        LCL_ApplyStepOffset(offset);
+
+      end_ref_mode(1);
+
+      break;
+    case REF_ModeIgnore:
+      /* Do nothing until the mode is changed */
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+get_clock_estimates(int manual,
+                    double measured_freq, double measured_skew,
+                    double *estimated_freq, double *estimated_skew,
+                    double *residual_freq)
+{
+  double gain, expected_freq, expected_skew, extra_skew;
+
+  /* We assume that the local clock is running according to our previously
+     determined value */
+  expected_freq = 0.0;
+  expected_skew = our_skew;
+
+  /* Set new frequency based on weighted average of the expected and measured
+     skew.  Disable updates that are based on totally unreliable frequency
+     information unless it is a manual reference. */
+  if (manual) {
+    gain = 1.0;
+  } else if (fabs(measured_skew) > max_update_skew) {
+    DEBUG_LOG("Skew %f too large to track", measured_skew);
+    gain = 0.0;
+  } else {
+    gain = 3.0 * SQUARE(expected_skew) /
+           (3.0 * SQUARE(expected_skew) + SQUARE(measured_skew));
+  }
+
+  gain = CLAMP(0.0, gain, 1.0);
+
+  *estimated_freq = expected_freq + gain * (measured_freq - expected_freq);
+  *residual_freq = measured_freq - *estimated_freq;
+
+  extra_skew = sqrt(SQUARE(expected_freq - *estimated_freq) * (1.0 - gain) +
+                    SQUARE(measured_freq - *estimated_freq) * gain);
+
+  *estimated_skew = expected_skew + gain * (measured_skew - expected_skew) + extra_skew;
+}
+
+/* ================================================== */
+
+static void
+fuzz_ref_time(struct timespec *ts)
+{
+  uint32_t rnd;
+
+  /* Add a random value from interval [-1.0, 0.0] */
+  UTI_GetRandomBytes(&rnd, sizeof (rnd));
+  UTI_AddDoubleToTimespec(ts, -(double)rnd / (uint32_t)-1, ts);
+}
+
+/* ================================================== */
+
+static double
+get_correction_rate(double offset_sd, double update_interval)
+{
+  /* We want to correct the offset quickly, but we also want to keep the
+     frequency error caused by the correction itself low.
+
+     Define correction rate as the area of the region bounded by the graph of
+     offset corrected in time.  Set the rate so that the time needed to correct
+     an offset equal to the current sourcestats stddev will be equal to the
+     update interval multiplied by the correction time ratio (assuming linear
+     adjustment).  The offset and the time needed to make the correction are
+     inversely proportional.
+
+     This is only a suggestion and it's up to the system driver how the
+     adjustment will be executed. */
+
+  return correction_time_ratio * 0.5 * offset_sd * update_interval;
+}
+
+/* ================================================== */
+
+void
+REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
+                 uint32_t ref_id, IPAddr *ref_ip, struct timespec *ref_time,
+                 double offset, double offset_sd,
+                 double frequency, double frequency_sd, double skew,
+                 double root_delay, double root_dispersion)
+{
+  double uncorrected_offset, accumulate_offset, step_offset;
+  double residual_frequency, local_abs_frequency;
+  double elapsed, mono_now, update_interval, orig_root_distance;
+  struct timespec now, raw_now;
+  int manual;
+
+  assert(initialised);
+
+  /* Special modes are implemented elsewhere */
+  if (mode != REF_ModeNormal) {
+    special_mode_sync(1, offset);
+    return;
+  }
+
+  manual = leap == LEAP_Unsynchronised;
+
+  mono_now = SCH_GetLastEventMonoTime();
+  LCL_ReadRawTime(&raw_now);
+  LCL_GetOffsetCorrection(&raw_now, &uncorrected_offset, NULL);
+  UTI_AddDoubleToTimespec(&raw_now, uncorrected_offset, &now);
+
+  elapsed = UTI_DiffTimespecsToDouble(&now, ref_time);
+  offset += elapsed * frequency;
+
+  if (last_ref_update != 0.0) {
+    update_interval = mono_now - last_ref_update;
+  } else {
+    update_interval = 0.0;
+  }
+
+  /* Get new estimates of the frequency and skew including the new data */
+  get_clock_estimates(manual, frequency, skew,
+                      &frequency, &skew, &residual_frequency);
+
+  if (!is_offset_ok(offset))
+    return;
+
+  orig_root_distance = our_root_delay / 2.0 + get_root_dispersion(&now);
+
+  are_we_synchronised = leap != LEAP_Unsynchronised;
+  our_stratum = stratum + 1;
+  our_ref_id = ref_id;
+  if (ref_ip)
+    our_ref_ip = *ref_ip;
+  else
+    our_ref_ip.family = IPADDR_UNSPEC;
+  our_ref_time = *ref_time;
+  our_skew = skew;
+  our_residual_freq = residual_frequency;
+  our_root_delay = root_delay;
+  our_root_dispersion = root_dispersion;
+  our_frequency_sd = frequency_sd;
+  our_offset_sd = offset_sd;
+  last_ref_update = mono_now;
+  last_ref_update_interval = update_interval;
+  last_offset = offset;
+
+  /* Check if the clock should be stepped */
+  if (is_step_limit_reached(offset, uncorrected_offset)) {
+    /* Cancel the uncorrected offset and correct the total offset by step */
+    accumulate_offset = uncorrected_offset;
+    step_offset = offset - uncorrected_offset;
+  } else {
+    accumulate_offset = offset;
+    step_offset = 0.0;
+  }
+
+  /* Adjust the clock */
+  LCL_AccumulateFrequencyAndOffset(frequency, accumulate_offset,
+                                   get_correction_rate(offset_sd, update_interval));
+    
+  maybe_log_offset(offset, raw_now.tv_sec);
+
+  if (step_offset != 0.0) {
+    if (LCL_ApplyStepOffset(step_offset))
+      LOG(LOGS_WARN, "System clock was stepped by %.6f seconds", -step_offset);
+  }
+
+  update_leap_status(leap, raw_now.tv_sec, 0);
+  update_sync_status(&now);
+
+  /* Add a random error of up to one second to the reference time to make it
+     less useful when disclosed to NTP and cmdmon clients for estimating
+     receive timestamps in the interleaved symmetric NTP mode */
+  fuzz_ref_time(&our_ref_time);
+
+  local_abs_frequency = LCL_ReadAbsoluteFrequency();
+
+  write_log(&now, combined_sources, local_abs_frequency,
+            offset, offset_sd, uncorrected_offset, orig_root_distance);
+
+  if (drift_file) {
+    /* Update drift file at most once per hour */
+    drift_file_age += update_interval;
+    if (drift_file_age >= MAX_DRIFTFILE_AGE) {
+      update_drift_file(local_abs_frequency, our_skew);
+      drift_file_age = 0.0;
+    }
+  }
+
+  /* Update fallback drifts */
+  if (fb_drifts && are_we_synchronised) {
+    update_fb_drifts(local_abs_frequency, update_interval);
+    schedule_fb_drift();
+  }
+
+  /* Update the moving average of squares of offset, quickly on start */
+  if (avg2_moving) {
+    avg2_offset += 0.1 * (SQUARE(offset) - avg2_offset);
+  } else {
+    if (avg2_offset > 0.0 && avg2_offset < SQUARE(offset))
+      avg2_moving = 1;
+    avg2_offset = SQUARE(offset);
+  }
+
+  ref_adjustments = 0;
+}
+
+/* ================================================== */
+
+int
+REF_AdjustReference(double offset, double frequency)
+{
+  double adj_corr_rate, ref_corr_rate, mono_now;
+
+  mono_now = SCH_GetLastEventMonoTime();
+  ref_adjustments++;
+
+  adj_corr_rate = get_correction_rate(fabs(offset), mono_now - last_ref_adjustment);
+  ref_corr_rate = get_correction_rate(our_offset_sd, last_ref_update_interval) /
+                  ref_adjustments;
+  last_ref_adjustment = mono_now;
+
+  return LCL_AccumulateFrequencyAndOffsetNoHandlers(frequency, offset,
+                                                    MAX(adj_corr_rate, ref_corr_rate));
+}
+
+/* ================================================== */
+
+void
+REF_SetManualReference
+(
+ struct timespec *ref_time,
+ double offset,
+ double frequency,
+ double skew
+)
+{
+  /* We are not synchronised to an external source, as such.  This is
+     only supposed to be used with the local source option, really.
+     Log as MANU in the tracking log, packets will have NTP_REFID_LOCAL. */
+  REF_SetReference(0, LEAP_Unsynchronised, 1, 0x4D414E55UL, NULL,
+                   ref_time, offset, 0.0, frequency, skew, skew, 0.0, 0.0);
+}
+
+/* ================================================== */
+
+void
+REF_SetUnsynchronised(void)
+{
+  /* Variables required for logging to statistics log */
+  struct timespec now, now_raw;
+  double uncorrected_offset;
+
+  assert(initialised);
+
+  /* Special modes are implemented elsewhere */
+  if (mode != REF_ModeNormal) {
+    special_mode_sync(0, 0.0);
+    return;
+  }
+
+  LCL_ReadRawTime(&now_raw);
+  LCL_GetOffsetCorrection(&now_raw, &uncorrected_offset, NULL);
+  UTI_AddDoubleToTimespec(&now_raw, uncorrected_offset, &now);
+
+  if (fb_drifts) {
+    schedule_fb_drift();
+  }
+
+  update_leap_status(LEAP_Unsynchronised, 0, 0);
+  our_ref_ip.family = IPADDR_INET4;
+  our_ref_ip.addr.in4 = 0;
+  our_stratum = 0;
+  are_we_synchronised = 0;
+
+  LCL_SetSyncStatus(0, 0.0, 0.0);
+
+  write_log(&now, 0, LCL_ReadAbsoluteFrequency(), 0.0, 0.0, uncorrected_offset,
+            our_root_delay / 2.0 + get_root_dispersion(&now));
+}
+
+/* ================================================== */
+
+void
+REF_UpdateLeapStatus(NTP_Leap leap)
+{
+  struct timespec raw_now, now;
+
+  /* Wait for a full reference update if not already synchronised */
+  if (!are_we_synchronised)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, &raw_now);
+
+  update_leap_status(leap, raw_now.tv_sec, 0);
+
+  /* Update also the synchronisation status */
+  update_sync_status(&now);
+}
+
+/* ================================================== */
+
+void
+REF_GetReferenceParams
+(
+ struct timespec *local_time,
+ int *is_synchronised,
+ NTP_Leap *leap_status,
+ int *stratum,
+ uint32_t *ref_id,
+ struct timespec *ref_time,
+ double *root_delay,
+ double *root_dispersion
+)
+{
+  double dispersion, delta;
+
+  assert(initialised);
+
+  if (are_we_synchronised) {
+    dispersion = get_root_dispersion(local_time);
+  } else {
+    dispersion = 0.0;
+  }
+
+  /* Local reference is active when enabled and the clock is not synchronised
+     or the root distance exceeds the threshold */
+
+  if (are_we_synchronised &&
+      !(enable_local_stratum && our_root_delay / 2 + dispersion > local_distance)) {
+
+    *is_synchronised = 1;
+
+    *stratum = our_stratum;
+
+    *leap_status = !leap_in_progress ? our_leap_status : LEAP_Unsynchronised;
+    *ref_id = our_ref_id;
+    *ref_time = our_ref_time;
+    *root_delay = our_root_delay;
+    *root_dispersion = dispersion;
+
+  } else if (enable_local_stratum) {
+
+    *is_synchronised = 0;
+
+    *stratum = local_stratum;
+    *ref_id = NTP_REFID_LOCAL;
+
+    /* Keep the reference timestamp up to date.  Adjust the timestamp to make
+       sure that the transmit timestamp cannot come before this (which might
+       fail a test of an NTP client). */
+    delta = UTI_DiffTimespecsToDouble(local_time, &local_ref_time);
+    if (delta > LOCAL_REF_UPDATE_INTERVAL || delta < 1.0) {
+      UTI_AddDoubleToTimespec(local_time, -1.0, &local_ref_time);
+      fuzz_ref_time(&local_ref_time);
+    }
+
+    *ref_time = local_ref_time;
+
+    /* Not much else we can do for leap second bits - maybe need to
+       have a way for the administrator to feed leap bits in */
+    *leap_status = LEAP_Normal;
+    
+    *root_delay = 0.0;
+    *root_dispersion = 0.0;
+    
+  } else {
+
+    *is_synchronised = 0;
+
+    *leap_status = LEAP_Unsynchronised;
+    *stratum = NTP_MAX_STRATUM;
+    *ref_id = NTP_REFID_UNSYNC;
+    UTI_ZeroTimespec(ref_time);
+    /* These values seem to be standard for a client, and
+       any peer or client of ours will ignore them anyway because
+       we don't claim to be synchronised */
+    *root_dispersion = 1.0;
+    *root_delay = 1.0;
+
+  }
+}
+
+/* ================================================== */
+
+int
+REF_GetOurStratum(void)
+{
+  struct timespec now_cooked, ref_time;
+  int synchronised, stratum;
+  NTP_Leap leap_status;
+  uint32_t ref_id;
+  double root_delay, root_dispersion;
+
+  SCH_GetLastEventTime(&now_cooked, NULL, NULL);
+  REF_GetReferenceParams(&now_cooked, &synchronised, &leap_status, &stratum,
+                         &ref_id, &ref_time, &root_delay, &root_dispersion);
+
+  return stratum;
+}
+
+/* ================================================== */
+
+int
+REF_GetOrphanStratum(void)
+{
+  if (!enable_local_stratum || !local_orphan || mode != REF_ModeNormal)
+    return NTP_MAX_STRATUM;
+  return local_stratum;
+}
+
+/* ================================================== */
+
+double
+REF_GetSkew(void)
+{
+  return our_skew;
+}
+
+/* ================================================== */
+
+void
+REF_ModifyMaxupdateskew(double new_max_update_skew)
+{
+  max_update_skew = new_max_update_skew * 1.0e-6;
+  LOG(LOGS_INFO, "New maxupdateskew %f ppm", new_max_update_skew);
+}
+
+/* ================================================== */
+
+void
+REF_ModifyMakestep(int limit, double threshold)
+{
+  make_step_limit = limit;
+  make_step_threshold = threshold;
+  LOG(LOGS_INFO, "New makestep %f %d", threshold, limit);
+}
+
+/* ================================================== */
+
+void
+REF_EnableLocal(int stratum, double distance, int orphan)
+{
+  enable_local_stratum = 1;
+  local_stratum = CLAMP(1, stratum, NTP_MAX_STRATUM - 1);
+  local_distance = distance;
+  local_orphan = !!orphan;
+  LOG(LOGS_INFO, "%s local reference mode", "Enabled");
+}
+
+/* ================================================== */
+
+void
+REF_DisableLocal(void)
+{
+  enable_local_stratum = 0;
+  LOG(LOGS_INFO, "%s local reference mode", "Disabled");
+}
+
+/* ================================================== */
+
+#define LEAP_SECOND_CLOSE 5
+
+static int
+is_leap_close(time_t t)
+{
+  return leap_when != 0 &&
+         t >= leap_when - LEAP_SECOND_CLOSE && t < leap_when + LEAP_SECOND_CLOSE;
+}
+
+/* ================================================== */
+
+int REF_IsLeapSecondClose(struct timespec *ts, double offset)
+{
+  struct timespec now, now_raw;
+
+  SCH_GetLastEventTime(&now, NULL, &now_raw);
+
+  if (is_leap_close(now.tv_sec) || is_leap_close(now_raw.tv_sec))
+    return 1;
+
+  if (ts && (is_leap_close(ts->tv_sec) || is_leap_close(ts->tv_sec + offset)))
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+REF_GetTaiOffset(struct timespec *ts)
+{
+  int tai_offset;
+
+  get_tz_leap(ts->tv_sec, &tai_offset);
+
+  return tai_offset;
+}
+
+/* ================================================== */
+
+void
+REF_GetTrackingReport(RPT_TrackingReport *rep)
+{
+  struct timespec now_raw, now_cooked;
+  double correction;
+  int synchronised;
+
+  LCL_ReadRawTime(&now_raw);
+  LCL_GetOffsetCorrection(&now_raw, &correction, NULL);
+  UTI_AddDoubleToTimespec(&now_raw, correction, &now_cooked);
+
+  REF_GetReferenceParams(&now_cooked, &synchronised,
+                         &rep->leap_status, &rep->stratum,
+                         &rep->ref_id, &rep->ref_time,
+                         &rep->root_delay, &rep->root_dispersion);
+
+  if (rep->stratum == NTP_MAX_STRATUM && !synchronised)
+    rep->stratum = 0;
+
+  rep->ip_addr.family = IPADDR_UNSPEC;
+  rep->current_correction = correction;
+  rep->freq_ppm = LCL_ReadAbsoluteFrequency();
+  rep->resid_freq_ppm = 0.0;
+  rep->skew_ppm = 0.0;
+  rep->last_update_interval = last_ref_update_interval;
+  rep->last_offset = last_offset;
+  rep->rms_offset = sqrt(avg2_offset);
+
+  if (synchronised) {
+    rep->ip_addr = our_ref_ip;
+    rep->resid_freq_ppm = 1.0e6 * our_residual_freq;
+    rep->skew_ppm = 1.0e6 * our_skew;
+  }
+}
diff --git a/reference.h b/reference.h
new file mode 100644
index 0000000..73454d4
--- /dev/null
+++ b/reference.h
@@ -0,0 +1,200 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the module that keeps track of the current
+  reference.
+
+  */
+
+#ifndef GOT_REFERENCE_H
+#define GOT_REFERENCE_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+#include "reports.h"
+
+/* Leap second handling modes */
+typedef enum {
+  REF_LeapModeSystem,
+  REF_LeapModeSlew,
+  REF_LeapModeStep,
+  REF_LeapModeIgnore,
+} REF_LeapMode;
+
+/* Init function */
+extern void REF_Initialise(void);
+
+/* Fini function */
+extern void REF_Finalise(void);
+
+typedef enum {
+  REF_ModeNormal,
+  REF_ModeInitStepSlew,
+  REF_ModeUpdateOnce,
+  REF_ModePrintOnce,
+  REF_ModeIgnore,
+} REF_Mode;
+
+/* Set reference update mode */
+extern void REF_SetMode(REF_Mode mode);
+
+/* Get reference update mode */
+extern REF_Mode REF_GetMode(void);
+
+/* Function type for handlers to be called back when mode ends */
+typedef void (*REF_ModeEndHandler)(int result);
+
+/* Set the handler for being notified of mode ending */
+extern void REF_SetModeEndHandler(REF_ModeEndHandler handler);
+
+/* Get leap second handling mode */
+extern REF_LeapMode REF_GetLeapMode(void);
+
+/* Function which takes a local cooked time and returns the estimated
+   time of the reference.  It also returns the other parameters
+   required for forming the outgoing NTP packet.
+
+   local_time is the cooked local time returned by the LCL module
+
+   is_synchronised indicates whether we are synchronised to anything
+   at the moment.
+
+   leap indicates the current leap status
+
+   stratum is the stratum of this machine, when considered to be sync'd to the
+   reference
+   
+   ref_id is the reference_id of the source
+
+   ref_time is the time at which the we last set the reference source up
+
+   root_delay is the root delay of the sample we are using
+
+   root_dispersion is the root dispersion of the sample we are using, with all the
+   skew etc added on.
+
+   */
+
+extern void REF_GetReferenceParams
+(
+ struct timespec *local_time,
+ int *is_synchronised,
+ NTP_Leap *leap,
+ int *stratum,
+ uint32_t *ref_id,
+ struct timespec *ref_time,
+ double *root_delay,
+ double *root_dispersion
+);
+
+/* Function called by the clock selection process to register a new
+   reference source and its parameters
+
+   stratum is the stratum of the reference
+
+   leap is the leap status read from the source
+
+   ref_id is the reference id of the reference
+
+   ref_time is the time at which the parameters are assumed to be
+   correct, in terms of local time
+
+   frequency is the amount of local clock gain relative to the
+   reference per unit time interval of the local clock
+
+   skew is the maximum estimated frequency error (so we are within
+   [frequency+-skew])
+
+   root_delay is the root delay of the sample we are using
+
+   root_dispersion is the root dispersion of the sample we are using
+
+   */
+
+extern void REF_SetReference
+(
+ int stratum,
+ NTP_Leap leap,
+ int combined_sources,
+ uint32_t ref_id,
+ IPAddr *ref_ip,
+ struct timespec *ref_time,
+ double offset,
+ double offset_sd,
+ double frequency,
+ double frequency_sd,
+ double skew,
+ double root_delay,
+ double root_dispersion
+);
+
+extern void REF_SetManualReference
+(
+ struct timespec *ref_time,
+ double offset,
+ double frequency,
+ double skew
+);
+
+/* Mark the local clock as unsynchronised */
+extern void
+REF_SetUnsynchronised(void);
+
+/* Make a small correction of the clock without updating the reference
+   parameters and calling the clock change handlers */
+extern int REF_AdjustReference(double offset, double frequency);
+
+/* Announce a leap second before the full reference update */
+extern void REF_UpdateLeapStatus(NTP_Leap leap);
+
+/* Return the current stratum of this host or 16 if the host is not
+   synchronised */
+extern int REF_GetOurStratum(void);
+
+/* Return stratum of the local reference if orphan mode is enabled */
+extern int REF_GetOrphanStratum(void);
+
+/* Return the current skew */
+extern double REF_GetSkew(void);
+
+/* Modify the setting for the maximum skew we are prepared to allow updates on (in ppm). */
+extern void REF_ModifyMaxupdateskew(double new_max_update_skew);
+
+/* Modify makestep settings */
+extern void REF_ModifyMakestep(int limit, double threshold);
+
+extern void REF_EnableLocal(int stratum, double distance, int orphan);
+extern void REF_DisableLocal(void);
+
+/* Check if either of the current raw and cooked time, and optionally a
+   provided timestamp with an offset, is close to a leap second */
+extern int REF_IsLeapSecondClose(struct timespec *ts, double offset);
+
+/* Return TAI-UTC offset corresponding to a time in UTC if available */
+extern int REF_GetTaiOffset(struct timespec *ts);
+
+extern void REF_GetTrackingReport(RPT_TrackingReport *rep);
+
+#endif /* GOT_REFERENCE_H */
diff --git a/regress.c b/regress.c
new file mode 100644
index 0000000..e767e2f
--- /dev/null
+++ b/regress.c
@@ -0,0 +1,704 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2016-2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Regression algorithms.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "regress.h"
+#include "logging.h"
+#include "util.h"
+
+#define MAX_POINTS 64
+
+void
+RGR_WeightedRegression
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1                    /* estimated standard deviation of
+                                   slope */
+
+ /* Could add correlation stuff later if required */
+)
+{
+  double P, Q, U, V, W;
+  double diff;
+  double u, ui, aa;
+  int i;
+
+  assert(n >= 3);
+
+  W = U = 0;
+  for (i=0; i<n; i++) {
+    U += x[i]        / w[i];
+    W += 1.0         / w[i];
+  }
+
+  u = U / W;
+
+  /* Calculate statistics from data */
+  P = Q = V = 0.0;
+  for (i=0; i<n; i++) {
+    ui = x[i] - u;
+    P += y[i]        / w[i];
+    Q += y[i] * ui   / w[i];
+    V += ui   * ui   / w[i];
+  }
+
+  *b1 = Q / V;
+  *b0 = (P / W) - (*b1) * u;
+
+  *s2 = 0.0;
+  for (i=0; i<n; i++) {
+    diff = y[i] - *b0 - *b1*x[i];
+    *s2 += diff*diff / w[i];
+  }
+
+  *s2 /= (double)(n-2);
+
+  *sb1 = sqrt(*s2 / V);
+  aa = u * (*sb1);
+  *sb0 = sqrt(*s2 / W + aa * aa);
+
+  *s2 *= (n / W); /* Giving weighted average of variances */
+}
+
+/* ================================================== */
+/* Get the coefficient to multiply the standard deviation by, to get a
+   particular size of confidence interval (assuming a t-distribution) */
+  
+double
+RGR_GetTCoef(int dof)
+{
+  /* Assuming now the 99.95% quantile */
+  static const float coefs[] =
+  { 636.6, 31.6, 12.92, 8.61, 6.869,
+    5.959, 5.408, 5.041, 4.781, 4.587,
+    4.437, 4.318, 4.221, 4.140, 4.073,
+    4.015, 3.965, 3.922, 3.883, 3.850,
+    3.819, 3.792, 3.768, 3.745, 3.725,
+    3.707, 3.690, 3.674, 3.659, 3.646,
+    3.633, 3.622, 3.611, 3.601, 3.591,
+    3.582, 3.574, 3.566, 3.558, 3.551};
+
+  if (dof <= 40) {
+    return coefs[dof-1];
+  } else {
+    return 3.5; /* Until I can be bothered to do something better */
+  }
+}
+
+/* ================================================== */
+/* Get 90% quantile of chi-square distribution */
+
+double
+RGR_GetChi2Coef(int dof)
+{
+  static const float coefs[] = {
+    2.706, 4.605, 6.251, 7.779, 9.236, 10.645, 12.017, 13.362,
+    14.684, 15.987, 17.275, 18.549, 19.812, 21.064, 22.307, 23.542,
+    24.769, 25.989, 27.204, 28.412, 29.615, 30.813, 32.007, 33.196,
+    34.382, 35.563, 36.741, 37.916, 39.087, 40.256, 41.422, 42.585,
+    43.745, 44.903, 46.059, 47.212, 48.363, 49.513, 50.660, 51.805,
+    52.949, 54.090, 55.230, 56.369, 57.505, 58.641, 59.774, 60.907,
+    62.038, 63.167, 64.295, 65.422, 66.548, 67.673, 68.796, 69.919,
+    71.040, 72.160, 73.279, 74.397, 75.514, 76.630, 77.745, 78.860
+  };
+
+  if (dof <= 64) {
+    return coefs[dof-1];
+  } else {
+    return 1.2 * dof; /* Until I can be bothered to do something better */
+  }
+}
+
+/* ================================================== */
+/* Critical value for number of runs of residuals with same sign.
+   5% critical region for now. */
+
+static char critical_runs[] = {
+  0,  0,  0,  0,  0,  0,  0,  0,  2,  3,
+  3,  3,  4,  4,  5,  5,  5,  6,  6,  7,
+  7,  7,  8,  8,  9,  9,  9, 10, 10, 11,
+ 11, 11, 12, 12, 13, 13, 14, 14, 14, 15,
+ 15, 16, 16, 17, 17, 18, 18, 18, 19, 19,
+ 20, 20, 21, 21, 21, 22, 22, 23, 23, 24,
+ 24, 25, 25, 26, 26, 26, 27, 27, 28, 28,
+ 29, 29, 30, 30, 30, 31, 31, 32, 32, 33,
+ 33, 34, 34, 35, 35, 35, 36, 36, 37, 37,
+ 38, 38, 39, 39, 40, 40, 40, 41, 41, 42,
+ 42, 43, 43, 44, 44, 45, 45, 46, 46, 46,
+ 47, 47, 48, 48, 49, 49, 50, 50, 51, 51,
+ 52, 52, 52, 53, 53, 54, 54, 55, 55, 56
+};
+
+/* ================================================== */
+
+static int
+n_runs_from_residuals(double *resid, int n)
+{
+  int nruns;
+  int i;
+  
+  nruns = 1;
+  for (i=1; i<n; i++) {
+    if (((resid[i-1] < 0.0) && (resid[i] < 0.0)) ||
+        ((resid[i-1] > 0.0) && (resid[i] > 0.0))) {
+      /* Nothing to do */
+    } else {
+      nruns++;
+    }
+  }
+  
+  return nruns;
+}
+
+/* ================================================== */
+/* Return a boolean indicating whether we had enough points for
+   regression */
+
+int
+RGR_FindBestRegression 
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+ int m,                         /* number of extra samples in x and y arrays
+                                   (negative index) which can be used to
+                                   extend runs test */
+ int min_samples,               /* minimum number of samples to be kept after
+                                   changing the starting index to pass the runs
+                                   test */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1,                   /* estimated standard deviation of
+                                   slope */
+
+ int *new_start,                /* the new starting index to make the
+                                   residuals pass the two tests */
+ 
+ int *n_runs,                   /* number of runs amongst the residuals */
+
+ int *dof                       /* degrees of freedom in statistics (needed
+                                   to get confidence intervals later) */
+
+)
+{
+  double P, Q, U, V, W; /* total */
+  double resid[MAX_POINTS * REGRESS_RUNS_RATIO];
+  double ss;
+  double a, b, u, ui, aa;
+
+  int start, resid_start, nruns, npoints;
+  int i;
+
+  assert(n <= MAX_POINTS && m >= 0);
+  assert(n * REGRESS_RUNS_RATIO < sizeof (critical_runs) / sizeof (critical_runs[0]));
+
+  if (n < MIN_SAMPLES_FOR_REGRESS) {
+    return 0;
+  }
+
+  start = 0;
+  do {
+
+    W = U = 0;
+    for (i=start; i<n; i++) {
+      U += x[i]        / w[i];
+      W += 1.0         / w[i];
+    }
+
+    u = U / W;
+
+    P = Q = V = 0.0;
+    for (i=start; i<n; i++) {
+      ui = x[i] - u;
+      P += y[i]        / w[i];
+      Q += y[i] * ui   / w[i];
+      V += ui   * ui   / w[i];
+    }
+
+    b = Q / V;
+    a = (P / W) - (b * u);
+
+    /* Get residuals also for the extra samples before start */
+    resid_start = n - (n - start) * REGRESS_RUNS_RATIO;
+    if (resid_start < -m)
+      resid_start = -m;
+
+    for (i=resid_start; i<n; i++) {
+      resid[i - resid_start] = y[i] - a - b*x[i];
+    }
+
+    /* Count number of runs */
+    nruns = n_runs_from_residuals(resid, n - resid_start); 
+
+    if (nruns > critical_runs[n - resid_start] ||
+        n - start <= MIN_SAMPLES_FOR_REGRESS ||
+        n - start <= min_samples) {
+      if (start != resid_start) {
+        /* Ignore extra samples in returned nruns */
+        nruns = n_runs_from_residuals(resid + (start - resid_start), n - start);
+      }
+      break;
+    } else {
+      /* Try dropping one sample at a time until the runs test passes. */
+      ++start;
+    }
+
+  } while (1);
+
+  /* Work out statistics from full dataset */
+  *b1 = b;
+  *b0 = a;
+
+  ss = 0.0;
+  for (i=start; i<n; i++) {
+    ss += resid[i - resid_start]*resid[i - resid_start] / w[i];
+  }
+
+  npoints = n - start;
+  ss /= (double)(npoints - 2);
+  *sb1 = sqrt(ss / V);
+  aa = u * (*sb1);
+  *sb0 = sqrt((ss / W) + (aa * aa));
+  *s2 = ss * (double) npoints / W;
+
+  *new_start = start;
+  *dof = npoints - 2;
+  *n_runs = nruns;
+
+  return 1;
+
+}
+
+/* ================================================== */
+
+#define EXCH(a,b) temp=(a); (a)=(b); (b)=temp
+
+/* ================================================== */
+/* Find the index'th biggest element in the array x of n elements.
+   flags is an array where a 1 indicates that the corresponding entry
+   in x is known to be sorted into its correct position and a 0
+   indicates that the corresponding entry is not sorted.  However, if
+   flags[m] = flags[n] = 1 with m<n, then x[m] must be <= x[n] and for
+   all i with m<i<n, x[m] <= x[i] <= x[n].  In practice, this means
+   flags[] has to be the result of a previous call to this routine
+   with the same array x, and is used to remember which parts of the
+   x[] array we have already sorted.
+
+   The approach used is a cut-down quicksort, where we only bother to
+   keep sorting the partition that contains the index we are after.
+   The approach comes from Numerical Recipes in C (ISBN
+   0-521-43108-5). */
+
+static double
+find_ordered_entry_with_flags(double *x, int n, int index, char *flags)
+{
+  int u, v, l, r;
+  double temp;
+  double piv;
+  int pivind;
+
+  assert(index >= 0);
+
+  /* If this bit of the array is already sorted, simple! */
+  if (flags[index]) {
+    return x[index];
+  }
+  
+  /* Find subrange to look at */
+  u = v = index;
+  while (u > 0 && !flags[u]) u--;
+  if (flags[u]) u++;
+
+  while (v < (n-1) && !flags[v]) v++;
+  if (flags[v]) v--;
+
+  do {
+    if (v - u < 2) {
+      if (x[v] < x[u]) {
+        EXCH(x[v], x[u]);
+      }
+      flags[v] = flags[u] = 1;
+      return x[index];
+    } else { 
+      pivind = (u + v) >> 1;
+      EXCH(x[u], x[pivind]);
+      piv = x[u]; /* New value */
+      l = u + 1;
+      r = v;
+      do {
+        while (l < v && x[l] < piv) l++;
+        while (x[r] > piv) r--;
+        if (r <= l) break;
+        EXCH(x[l], x[r]);
+        l++;
+        r--;
+      } while (1);
+      EXCH(x[u], x[r]);
+      flags[r] = 1; /* Pivot now in correct place */
+      if (index == r) {
+        return x[r];
+      } else if (index < r) {
+        v = r - 1;
+      } else if (index > r) {
+        u = l;
+      }
+    }
+  } while (1);
+}
+
+/* ================================================== */
+
+#if 0
+/* Not used, but this is how it can be done */
+static double
+find_ordered_entry(double *x, int n, int index)
+{
+  char flags[MAX_POINTS];
+
+  memset(flags, 0, n * sizeof (flags[0]));
+  return find_ordered_entry_with_flags(x, n, index, flags);
+}
+#endif
+
+/* ================================================== */
+/* Find the median entry of an array x[] with n elements. */
+
+static double
+find_median(double *x, int n)
+{
+  int k;
+  char flags[MAX_POINTS];
+
+  memset(flags, 0, n * sizeof (flags[0]));
+  k = n>>1;
+  if (n&1) {
+    return find_ordered_entry_with_flags(x, n, k, flags);
+  } else {
+    return 0.5 * (find_ordered_entry_with_flags(x, n, k, flags) +
+                  find_ordered_entry_with_flags(x, n, k-1, flags));
+  }
+}
+
+/* ================================================== */
+
+double
+RGR_FindMedian(double *x, int n)
+{
+  double tmp[MAX_POINTS];
+
+  assert(n > 0 && n <= MAX_POINTS);
+  memcpy(tmp, x, n * sizeof (tmp[0]));
+
+  return find_median(tmp, n);
+}
+
+/* ================================================== */
+/* This function evaluates the equation
+
+   \sum_{i=0}^{n-1} x_i sign(y_i - a - b x_i)
+
+   and chooses the value of a that minimises the absolute value of the
+   result.  (See pp703-704 of Numerical Recipes in C). */
+
+static void
+eval_robust_residual
+(double *x,                     /* The independent points */
+ double *y,                     /* The dependent points */
+ int n,                         /* Number of points */
+ double b,                      /* Slope */
+ double *aa,                    /* Intercept giving smallest absolute
+                                   value for the above equation */
+ double *rr                     /* Corresponding value of equation */
+)
+{
+  int i;
+  double a, res, del;
+  double d[MAX_POINTS];
+
+  for (i=0; i<n; i++) {
+    d[i] = y[i] - b * x[i];
+  }
+  
+  a = find_median(d, n);
+
+  res = 0.0;
+  for (i=0; i<n; i++) {
+    del = y[i] - a - b * x[i];
+    if (del > 0.0) {
+      res += x[i];
+    } else if (del < 0.0) {
+      res -= x[i];
+    }
+  }
+
+  *aa = a;
+  *rr = res;
+}
+
+/* ================================================== */
+/* This routine performs a 'robust' regression, i.e. one which has low
+   susceptibility to outliers amongst the data.  If one thinks of a
+   normal (least squares) linear regression in 2D being analogous to
+   the arithmetic mean in 1D, this algorithm in 2D is roughly
+   analogous to the median in 1D.  This algorithm seems to work quite
+   well until the number of outliers is approximately half the number
+   of data points.
+
+   The return value is a status indicating whether there were enough
+   data points to run the routine or not. */
+
+int
+RGR_FindBestRobustRegression
+(double *x,                     /* The independent axis points */
+ double *y,                     /* The dependent axis points (which
+                                   may contain outliers). */
+ int n,                         /* The number of points */
+ double tol,                    /* The tolerance required in
+                                   determining the value of b1 */
+ double *b0,                    /* The estimated Y-axis intercept */
+ double *b1,                    /* The estimated slope */
+ int *n_runs,                   /* The number of runs of residuals */
+ int *best_start                /* The best starting index */
+)
+{
+  int i;
+  int start;
+  int n_points;
+  double a, b;
+  double P, U, V, W, X;
+  double resid, resids[MAX_POINTS];
+  double blo, bhi, bmid, rlo, rhi, rmid;
+  double s2, sb, incr;
+  double mx, dx, my, dy;
+  int nruns = 0;
+
+  assert(n <= MAX_POINTS);
+
+  if (n < 2) {
+    return 0;
+  } else if (n == 2) {
+    /* Just a straight line fit (we need this for the manual mode) */
+    *b1 = (y[1] - y[0]) / (x[1] - x[0]);
+    *b0 = y[0] - (*b1) * x[0];
+    *n_runs = 0;
+    *best_start = 0;
+    return 1;
+  }
+
+  /* else at least 3 points, apply normal algorithm */
+
+  start = 0;
+
+  /* Loop to strip oldest points that cause the regression residuals
+     to fail the number of runs test */
+  do {
+
+    n_points = n - start;
+
+    /* Use standard least squares regression to get starting estimate */
+
+    P = U = 0.0;
+    for (i=start; i<n; i++) {
+      P += y[i];
+      U += x[i];
+    }
+
+    W = (double) n_points;
+
+    my = P/W;
+    mx = U/W;
+
+    X = V = 0.0;
+    for (i=start; i<n; i++) {
+      dy = y[i] - my;
+      dx = x[i] - mx;
+      X += dy * dx;
+      V += dx * dx;
+    }
+
+    b = X / V;
+    a = my - b*mx;
+
+    s2 = 0.0;
+    for (i=start; i<n; i++) {
+      resid = y[i] - a - b * x[i];
+      s2 += resid * resid;
+    }
+
+    /* Need to expand range of b to get a root in the interval.
+       Estimate standard deviation of b and expand range about b based
+       on that. */
+    sb = sqrt(s2 * W/V);
+    incr = MAX(sb, tol);
+  
+    do {
+      incr *= 2.0;
+
+      /* Give up if the interval is too large */
+      if (incr > 100.0)
+        return 0;
+
+      blo = b - incr;
+      bhi = b + incr;
+
+      /* We don't want 'a' yet */
+      eval_robust_residual(x + start, y + start, n_points, blo, &a, &rlo);
+      eval_robust_residual(x + start, y + start, n_points, bhi, &a, &rhi);
+
+    } while (rlo * rhi >= 0.0); /* fn vals have same sign or one is zero,
+                                   i.e. root not in interval (rlo, rhi). */
+
+    /* OK, so the root for b lies in (blo, bhi). Start bisecting */
+    do {
+      bmid = 0.5 * (blo + bhi);
+      if (!(blo < bmid && bmid < bhi))
+        break;
+      eval_robust_residual(x + start, y + start, n_points, bmid, &a, &rmid);
+      if (rmid == 0.0) {
+        break;
+      } else if (rmid * rlo > 0.0) {
+        blo = bmid;
+        rlo = rmid;
+      } else if (rmid * rhi > 0.0) {
+        bhi = bmid;
+        rhi = rmid;
+      } else {
+        assert(0);
+      }
+    } while (bhi - blo > tol);
+
+    *b0 = a;
+    *b1 = bmid;
+
+    /* Number of runs test, but not if we're already down to the
+       minimum number of points */
+    if (n_points == MIN_SAMPLES_FOR_REGRESS) {
+      break;
+    }
+
+    for (i=start; i<n; i++) {
+      resids[i] = y[i] - a - bmid * x[i];
+    }
+
+    nruns = n_runs_from_residuals(resids + start, n_points);
+
+    if (nruns > critical_runs[n_points]) {
+      break;
+    } else {
+      start++;
+    }
+
+  } while (1);
+
+  *n_runs = nruns;
+  *best_start = start;
+
+  return 1;
+
+}
+
+/* ================================================== */
+/* This routine performs linear regression with two independent variables.
+   It returns non-zero status if there were enough data points and there
+   was a solution. */
+
+int
+RGR_MultipleRegress
+(double *x1,                    /* first independent variable */
+ double *x2,                    /* second independent variable */
+ double *y,                     /* measured data */
+
+ int n,                         /* number of data points */
+
+ /* The results */
+ double *b2                     /* estimated second slope */
+                                /* other values are not needed yet */
+)
+{
+  double Sx1, Sx2, Sx1x1, Sx1x2, Sx2x2, Sx1y, Sx2y, Sy;
+  double U, V, V1, V2, V3;
+  int i;
+
+  if (n < 4)
+    return 0;
+
+  Sx1 = Sx2 = Sx1x1 = Sx1x2 = Sx2x2 = Sx1y = Sx2y = Sy = 0.0;
+
+  for (i = 0; i < n; i++) {
+    Sx1 += x1[i];
+    Sx2 += x2[i];
+    Sx1x1 += x1[i] * x1[i];
+    Sx1x2 += x1[i] * x2[i];
+    Sx2x2 += x2[i] * x2[i];
+    Sx1y += x1[i] * y[i];
+    Sx2y += x2[i] * y[i];
+    Sy += y[i];
+  }
+
+  U = n * (Sx1x2 * Sx1y - Sx1x1 * Sx2y) +
+      Sx1 * Sx1 * Sx2y - Sx1 * Sx2 * Sx1y +
+      Sy * (Sx2 * Sx1x1 - Sx1 * Sx1x2);
+
+  V1 = n * (Sx1x2 * Sx1x2 - Sx1x1 * Sx2x2);
+  V2 = Sx1 * Sx1 * Sx2x2 + Sx2 * Sx2 * Sx1x1;
+  V3 = -2.0 * Sx1 * Sx2 * Sx1x2;
+  V = V1 + V2 + V3;
+
+  /* Check if there is a (numerically stable) solution */
+  if (fabs(V) * 1.0e10 <= -V1 + V2 + fabs(V3))
+    return 0;
+
+  *b2 = U / V;
+
+  return 1;
+}
diff --git a/regress.h b/regress.h
new file mode 100644
index 0000000..90055da
--- /dev/null
+++ b/regress.h
@@ -0,0 +1,137 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for regression routine(s)
+
+  */
+
+#ifndef GOT_REGRESS_H
+#define GOT_REGRESS_H
+
+extern void
+RGR_WeightedRegression
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance (weighted) of
+                                   data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1                    /* estimated standard deviation of
+                                   slope */
+
+ /* Could add correlation stuff later if required */
+);
+
+/* Return the weighting to apply to the standard deviation to get a
+   given size of confidence interval assuming a T distribution */
+
+extern double RGR_GetTCoef(int dof);
+
+/* Return the value to apply to the variance to make an upper one-sided
+   test assuming a chi-square distribution. */
+
+extern double RGR_GetChi2Coef(int dof);
+
+/* Maximum ratio of number of points used for runs test to number of regression
+   points */
+#define REGRESS_RUNS_RATIO 2
+
+/* Minimum number of samples for regression */
+#define MIN_SAMPLES_FOR_REGRESS 3
+
+/* Return a status indicating whether there were enough points to
+   carry out the regression */
+
+extern int
+RGR_FindBestRegression 
+(double *x,                     /* independent variable */
+ double *y,                     /* measured data */
+ double *w,                     /* weightings (large => data
+                                   less reliable) */
+ 
+ int n,                         /* number of data points */
+ int m,                         /* number of extra samples in x and y arrays
+                                   (negative index) which can be used to
+                                   extend runs test */
+ int min_samples,               /* minimum number of samples to be kept after
+                                   changing the starting index to pass the runs
+                                   test */
+
+ /* And now the results */
+
+ double *b0,                    /* estimated y axis intercept */
+ double *b1,                    /* estimated slope */
+ double *s2,                    /* estimated variance of data points */
+ 
+ double *sb0,                   /* estimated standard deviation of
+                                   intercept */
+ double *sb1,                   /* estimated standard deviation of
+                                   slope */
+
+ int *new_start,                /* the new starting index to make the
+                                   residuals pass the two tests */
+
+ int *n_runs,                   /* number of runs amongst the residuals */
+
+ int *dof                       /* degrees of freedom in statistics (needed
+                                   to get confidence intervals later) */
+
+);
+
+int
+RGR_FindBestRobustRegression
+(double *x,
+ double *y,
+ int n,
+ double tol,
+ double *b0,
+ double *b1,
+ int *n_runs,
+ int *best_start);
+
+int
+RGR_MultipleRegress
+(double *x1,                    /* first independent variable */
+ double *x2,                    /* second independent variable */
+ double *y,                     /* measured data */
+
+ int n,                         /* number of data points */
+
+ /* The results */
+ double *b2                     /* estimated second slope */
+);
+
+/* Return the median value from an array */
+extern double RGR_FindMedian(double *x, int n);
+
+#endif /* GOT_REGRESS_H */
diff --git a/reports.h b/reports.h
new file mode 100644
index 0000000..0150fc6
--- /dev/null
+++ b/reports.h
@@ -0,0 +1,212 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Data structure definitions within the daemon for various reports that
+  can be generated */
+
+#ifndef GOT_REPORTS_H
+#define GOT_REPORTS_H
+
+#include "sysincl.h"
+#include "addressing.h"
+#include "ntp.h"
+
+typedef struct {
+  IPAddr ip_addr;
+  int stratum;
+  int poll;
+  enum {RPT_NTP_CLIENT, RPT_NTP_PEER, RPT_LOCAL_REFERENCE} mode;
+  enum {
+    RPT_NONSELECTABLE,
+    RPT_FALSETICKER,
+    RPT_JITTERY,
+    RPT_SELECTABLE,
+    RPT_UNSELECTED,
+    RPT_SELECTED,
+  } state;
+
+  int reachability;
+  unsigned long latest_meas_ago; /* seconds */
+  double orig_latest_meas; /* seconds */
+  double latest_meas; /* seconds */
+  double latest_meas_err; /* seconds */
+} RPT_SourceReport ;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  int stratum;
+  NTP_Leap leap_status;
+  struct timespec ref_time;
+  double current_correction;
+  double last_offset;
+  double rms_offset;
+  double freq_ppm;
+  double resid_freq_ppm;
+  double skew_ppm;
+  double root_delay;
+  double root_dispersion;
+  double last_update_interval;
+} RPT_TrackingReport;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  unsigned long n_samples;
+  unsigned long n_runs;
+  unsigned long span_seconds;
+  double resid_freq_ppm;
+  double skew_ppm;
+  double sd;
+  double est_offset;
+  double est_offset_err;
+} RPT_SourcestatsReport;
+
+typedef struct {
+  struct timespec ref_time;
+  unsigned long n_samples;
+  unsigned long n_runs;
+  unsigned long span_seconds;
+  double rtc_seconds_fast;
+  double rtc_gain_rate_ppm;
+} RPT_RTC_Report;
+
+typedef struct {
+  IPAddr ip_addr;
+  uint32_t ntp_hits;
+  uint32_t nke_hits;
+  uint32_t cmd_hits;
+  uint16_t ntp_drops;
+  uint16_t nke_drops;
+  uint16_t cmd_drops;
+  int8_t ntp_interval;
+  int8_t nke_interval;
+  int8_t cmd_interval;
+  int8_t ntp_timeout_interval;
+  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
+  uint32_t last_cmd_hit_ago;
+} RPT_ClientAccessByIndex_Report;
+
+typedef struct {
+  uint64_t ntp_hits;
+  uint64_t nke_hits;
+  uint64_t cmd_hits;
+  uint64_t ntp_drops;
+  uint64_t nke_drops;
+  uint64_t cmd_drops;
+  uint64_t log_drops;
+  uint64_t ntp_auth_hits;
+  uint64_t ntp_interleaved_hits;
+  uint64_t ntp_timestamps;
+  uint64_t ntp_span_seconds;
+  uint64_t ntp_daemon_rx_timestamps;
+  uint64_t ntp_daemon_tx_timestamps;
+  uint64_t ntp_kernel_rx_timestamps;
+  uint64_t ntp_kernel_tx_timestamps;
+  uint64_t ntp_hw_rx_timestamps;
+  uint64_t ntp_hw_tx_timestamps;
+} RPT_ServerStatsReport;
+
+typedef struct {
+  struct timespec when;
+  double slewed_offset;
+  double orig_offset;
+  double residual;
+} RPT_ManualSamplesReport;
+
+typedef struct {
+  int online;
+  int offline;
+  int burst_online;
+  int burst_offline;
+  int unresolved;
+} RPT_ActivityReport;
+
+typedef struct {
+  int active;
+  int leap_only;
+  double offset;
+  double freq_ppm;
+  double wander_ppm;
+  double last_update_ago;
+  double remaining_time;
+} RPT_SmoothingReport;
+
+typedef struct {
+  IPAddr remote_addr;
+  IPAddr local_addr;
+  uint16_t remote_port;
+  uint8_t leap;
+  uint8_t version;
+  uint8_t mode;
+  uint8_t stratum;
+  int8_t poll;
+  int8_t precision;
+  double root_delay;
+  double root_dispersion;
+  uint32_t ref_id;
+  struct timespec ref_time;
+  double offset;
+  double peer_delay;
+  double peer_dispersion;
+  double response_time;
+  double jitter_asymmetry;
+  uint16_t tests;
+  int interleaved;
+  int authenticated;
+  char tx_tss_char;
+  char rx_tss_char;
+  uint32_t total_tx_count;
+  uint32_t total_rx_count;
+  uint32_t total_valid_count;
+  uint32_t total_good_count;
+} RPT_NTPReport;
+
+typedef struct {
+  NTP_AuthMode mode;
+  uint32_t key_id;
+  int key_type;
+  int key_length;
+  int ke_attempts;
+  uint32_t last_ke_ago;
+  int cookies;
+  int cookie_length;
+  int nak;
+} RPT_AuthReport;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  char state_char;
+  int authentication;
+  NTP_Leap leap;
+  int conf_options;
+  int eff_options;
+  uint32_t last_sample_ago;
+  double score;
+  double lo_limit;
+  double hi_limit;
+} RPT_SelectReport;
+
+#endif /* GOT_REPORTS_H */
diff --git a/rtc.c b/rtc.c
new file mode 100644
index 0000000..d946541
--- /dev/null
+++ b/rtc.c
@@ -0,0 +1,242 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "rtc.h"
+#include "local.h"
+#include "logging.h"
+#include "conf.h"
+
+#if defined LINUX && defined FEAT_RTC
+#include "rtc_linux.h"
+#endif /* defined LINUX */
+
+/* ================================================== */
+
+static int driver_initialised = 0;
+static int driver_preinit_ok = 0;
+
+static struct {
+  int  (*init)(void);
+  void (*fini)(void);
+  int  (*time_pre_init)(time_t driftfile_time);
+  void (*time_init)(void (*after_hook)(void*), void *anything);
+  void (*start_measurements)(void);
+  int  (*write_parameters)(void);
+  int  (*get_report)(RPT_RTC_Report *report);
+  int  (*trim)(void);
+} driver =
+{
+#if defined LINUX && defined FEAT_RTC
+  RTC_Linux_Initialise,
+  RTC_Linux_Finalise,
+  RTC_Linux_TimePreInit,
+  RTC_Linux_TimeInit,
+  RTC_Linux_StartMeasurements,
+  RTC_Linux_WriteParameters,
+  RTC_Linux_GetReport,
+  RTC_Linux_Trim
+#else
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL,
+  NULL
+#endif 
+};
+     
+/* ================================================== */
+/* Get the last modification time of the driftfile */
+
+static time_t
+get_driftfile_time(void)
+{
+  struct stat buf;
+  char *drift_file;
+
+  drift_file = CNF_GetDriftFile();
+  if (!drift_file)
+    return 0;
+
+  if (stat(drift_file, &buf))
+    return 0;
+
+  return buf.st_mtime;
+}
+
+/* ================================================== */
+/* Set the system time to the driftfile time if it's in the future */
+
+static void
+apply_driftfile_time(time_t t)
+{
+  struct timespec now;
+
+  LCL_ReadCookedTime(&now, NULL);
+
+  if (now.tv_sec < t) {
+    if (LCL_ApplyStepOffset(now.tv_sec - t))
+      LOG(LOGS_INFO, "System time restored from driftfile");
+  }
+}
+
+/* ================================================== */
+
+void
+RTC_Initialise(int initial_set)
+{
+  time_t driftfile_time;
+  char *file_name;
+
+  /* If the -s option was specified, try to do an initial read of the RTC and
+     set the system time to it.  Also, read the last modification time of the
+     driftfile (i.e. system time when chronyd was previously stopped) and set
+     the system time to it if it's in the future to bring the clock closer to
+     the true time when the RTC is broken (e.g. it has no battery), is missing,
+     or there is no RTC driver. */
+  if (initial_set) {
+    driftfile_time = get_driftfile_time();
+
+    if (driver.time_pre_init && driver.time_pre_init(driftfile_time)) {
+      driver_preinit_ok = 1;
+    } else {
+      driver_preinit_ok = 0;
+      if (driftfile_time)
+        apply_driftfile_time(driftfile_time);
+    }
+  }
+
+  driver_initialised = 0;
+
+  /* This is how we tell whether the user wants to load the RTC
+     driver, if he is on a machine where it is an option. */
+  file_name = CNF_GetRtcFile();
+
+  if (file_name) {
+    if (CNF_GetRtcSync()) {
+      LOG_FATAL("rtcfile directive cannot be used with rtcsync");
+    }
+
+    if (driver.init) {
+      if ((driver.init)()) {
+        driver_initialised = 1;
+      } else {
+        LOG(LOGS_ERR, "RTC driver could not be initialised");
+      }
+    } else {
+      LOG(LOGS_ERR, "RTC not supported on this operating system");
+    }
+  }
+}
+
+/* ================================================== */
+
+void
+RTC_Finalise(void)
+{
+  if (driver_initialised) {
+    (driver.fini)();
+  }
+}
+
+/* ================================================== */
+/* Start the processing to get a single measurement from the real time
+   clock, and use it to trim the system time, based on knowing the
+   drift rate of the RTC and the error the last time we set it.  If the
+   TimePreInit routine has succeeded, we can be sure that the trim required
+   is not *too* large.
+
+   We are called with a hook to a function to be called after the
+   initialisation is complete.  We also call this if we cannot do the
+   initialisation. */
+
+void
+RTC_TimeInit(void (*after_hook)(void *), void *anything)
+{
+  if (driver_initialised && driver_preinit_ok) {
+    (driver.time_init)(after_hook, anything);
+  } else {
+    (after_hook)(anything);
+  }
+}
+
+/* ================================================== */
+/* Start the RTC measurement process */
+
+void
+RTC_StartMeasurements(void)
+{
+  if (driver_initialised) {
+    (driver.start_measurements)();
+  }
+  /* Benign if driver not present */
+}
+
+/* ================================================== */
+/* Write RTC information out to RTC file.  Return 0 for success, 1 if
+   RTC driver not running, or 2 if the file cannot be written. */
+
+int
+RTC_WriteParameters(void)
+{
+  if (driver_initialised) {
+    return (driver.write_parameters)();
+  } else {
+    return RTC_ST_NODRV;
+  }
+}
+
+/* ================================================== */
+
+int
+RTC_GetReport(RPT_RTC_Report *report)
+{
+  if (driver_initialised) {
+    return (driver.get_report)(report);
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+RTC_Trim(void)
+{
+  if (driver_initialised) {
+    return (driver.trim)();
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
diff --git a/rtc.h b/rtc.h
new file mode 100644
index 0000000..8fd677b
--- /dev/null
+++ b/rtc.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  */
+
+#ifndef GOT_RTC_H
+#define GOT_RTC_H
+
+#include "reports.h"
+
+extern void RTC_Initialise(int initial_set);
+extern void RTC_Finalise(void);
+extern void RTC_TimeInit(void (*after_hook)(void *), void *anything);
+extern void RTC_StartMeasurements(void);
+extern int  RTC_GetReport(RPT_RTC_Report *report);
+
+#define RTC_ST_OK 0
+#define RTC_ST_NODRV 1
+#define RTC_ST_BADFILE 2
+
+extern int RTC_WriteParameters(void);
+
+extern int RTC_Trim(void);
+
+#endif /* GOT_RTC_H */
diff --git a/rtc_linux.c b/rtc_linux.c
new file mode 100644
index 0000000..58b625b
--- /dev/null
+++ b/rtc_linux.c
@@ -0,0 +1,1072 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2012-2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Real-time clock driver for linux.  This interfaces the program with
+  the clock that keeps time when the machine is turned off.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <linux/rtc.h>
+
+#include "logging.h"
+#include "sched.h"
+#include "local.h"
+#include "util.h"
+#include "sys_linux.h"
+#include "reference.h"
+#include "regress.h"
+#include "rtc.h"
+#include "rtc_linux.h"
+#include "conf.h"
+#include "memory.h"
+
+/* ================================================== */
+/* Forward prototypes */
+
+static void measurement_timeout(void *any);
+
+static void read_from_device(int fd_, int event, void *any);
+
+/* ================================================== */
+
+typedef enum {
+  OM_NORMAL,
+  OM_INITIAL,
+  OM_AFTERTRIM
+} OperatingMode;
+
+static OperatingMode operating_mode = OM_NORMAL;
+
+/* ================================================== */
+
+static int fd;
+
+#define LOWEST_MEASUREMENT_PERIOD 15
+#define HIGHEST_MEASUREMENT_PERIOD 480
+#define N_SAMPLES_PER_REGRESSION 1
+
+static int measurement_period = LOWEST_MEASUREMENT_PERIOD;
+
+static SCH_TimeoutID timeout_id = 0;
+
+static int skip_interrupts;
+
+/* ================================================== */
+
+/* Maximum number of samples held */
+#define MAX_SAMPLES 64
+
+/* Real time clock samples.  We store the seconds count as originally
+   measured. */
+static time_t *rtc_sec = NULL;
+
+/* Reference time, against which delta times on the RTC scale are measured */
+static time_t rtc_ref;
+
+/* System clock samples associated with the above samples. */
+static struct timespec *system_times = NULL;
+
+/* Number of samples currently stored. */
+static int n_samples;   
+
+/* Number of new samples since last regression */
+static int n_samples_since_regression;
+
+/* Number of runs of residuals in last regression (for logging) */
+static int n_runs;
+
+/* Coefficients */
+/* Whether they are valid */
+static int coefs_valid;
+
+/* Reference time */
+static time_t coef_ref_time;
+/* Number of seconds by which RTC was fast of the system time at coef_ref_time */
+static double coef_seconds_fast;
+
+/* Estimated number of seconds that RTC gains relative to system time
+   for each second of ITS OWN time */
+static double coef_gain_rate;
+
+/* Gain rate saved just before we step the RTC to correct it to the
+   nearest second, so that we can write a useful set of coefs to the
+   RTC data file once we have reacquired its offset after the step */
+static double saved_coef_gain_rate;
+
+/* Threshold for automatic RTC trimming in seconds, zero when disabled */
+static double autotrim_threshold;
+
+/* Filename supplied by config file where RTC coefficients are
+   stored. */
+static char *coefs_file_name;
+
+/* ================================================== */
+/* Coefficients read from file at start of run. */
+
+/* Whether we have tried to load the coefficients */
+static int tried_to_load_coefs = 0;
+
+/* Whether valid coefficients were read */
+static int valid_coefs_from_file = 0;
+
+/* Coefs read in */
+static time_t file_ref_time;
+static double file_ref_offset, file_rate_ppm;
+
+/* ================================================== */
+
+/* Flag to remember whether to assume the RTC is running on UTC */
+static int rtc_on_utc;
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+
+static void (*after_init_hook)(void *) = NULL;
+static void *after_init_hook_arg = NULL;
+
+/* ================================================== */
+
+static void
+discard_samples(int new_first)
+{
+  int n_to_save;
+
+  assert(new_first >= 0 && new_first < n_samples);
+
+  n_to_save = n_samples - new_first;
+
+  memmove(rtc_sec, rtc_sec + new_first, n_to_save * sizeof(time_t));
+  memmove(system_times, system_times + new_first, n_to_save * sizeof(struct timespec));
+
+  n_samples = n_to_save;
+}
+
+/* ================================================== */
+
+#define NEW_FIRST_WHEN_FULL 4
+
+static void
+accumulate_sample(time_t rtc, struct timespec *sys)
+{
+
+  if (n_samples == MAX_SAMPLES) {
+    /* Discard oldest samples */
+    discard_samples(NEW_FIRST_WHEN_FULL);
+  }
+
+  /* Discard all samples if the RTC was stepped back (not our trim) */
+  if (n_samples > 0 && rtc_sec[n_samples - 1] >= rtc) {
+    DEBUG_LOG("RTC samples discarded");
+    n_samples = 0;
+  }
+
+  /* Always use most recent sample as reference */
+  rtc_ref = rtc;
+  rtc_sec[n_samples] = rtc;
+  system_times[n_samples] = *sys;
+  ++n_samples_since_regression;
+  ++n_samples;
+}
+
+/* ================================================== */
+/* The new_sample flag is to indicate whether to adjust the
+   measurement period depending on the behaviour of the standard
+   deviation. */
+
+static void
+run_regression(int new_sample,
+               int *valid,
+               time_t *ref,
+               double *fast,
+               double *slope)
+{
+  double rtc_rel[MAX_SAMPLES]; /* Relative times on RTC axis */
+  double offsets[MAX_SAMPLES]; /* How much the RTC is fast of the system clock */
+  int i;
+  double est_intercept, est_slope;
+  int best_new_start;
+
+  if (n_samples > 0) {
+
+    for (i=0; i<n_samples; i++) {
+      rtc_rel[i] = (double)(rtc_sec[i] - rtc_ref);
+      offsets[i] = ((double) (rtc_ref - system_times[i].tv_sec) -
+                    (1.0e-9 * system_times[i].tv_nsec) +
+                    rtc_rel[i]);
+
+    }
+
+    if (RGR_FindBestRobustRegression
+        (rtc_rel, offsets,
+         n_samples, 1.0e-9,
+         &est_intercept, &est_slope,
+         &n_runs,
+         &best_new_start)) {
+
+      /* Calculate and store coefficients.  We don't do any error
+         bounds processing on any of these. */
+      *valid = 1;
+      *ref = rtc_ref;
+      *fast = est_intercept;
+      *slope = est_slope;
+
+      if (best_new_start > 0) {
+        discard_samples(best_new_start);
+      }
+
+
+    } else {
+      /* Keep existing coefficients. */
+    }
+  } else {
+    /* Keep existing coefficients. */
+  }
+
+}
+
+/* ================================================== */
+
+static void
+slew_samples
+(struct timespec *raw, struct timespec *cooked,
+ double dfreq,
+ double doffset,
+ LCL_ChangeType change_type,
+ void *anything)
+{
+  int i;
+  double delta_time;
+  double old_seconds_fast, old_gain_rate;
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    /* Drop all samples. */
+    n_samples = 0;
+  }
+
+  for (i=0; i<n_samples; i++) {
+    UTI_AdjustTimespec(system_times + i, cooked, system_times + i, &delta_time,
+        dfreq, doffset);
+  }
+
+  old_seconds_fast = coef_seconds_fast;
+  old_gain_rate = coef_gain_rate;
+
+  if (coefs_valid) {
+    coef_seconds_fast += doffset;
+    coef_gain_rate += dfreq * (1.0 - coef_gain_rate);
+  }
+
+  DEBUG_LOG("dfreq=%.8f doffset=%.6f old_fast=%.6f old_rate=%.3f new_fast=%.6f new_rate=%.3f",
+      dfreq, doffset,
+      old_seconds_fast, 1.0e6 * old_gain_rate,
+      coef_seconds_fast, 1.0e6 * coef_gain_rate);
+}
+
+/* ================================================== */
+
+/* Function to convert from a time_t value represenging UTC to the
+   corresponding real time clock 'DMY HMS' form, taking account of
+   whether the user runs his RTC on the local time zone or UTC */
+
+static struct tm *
+rtc_from_t(const time_t *t)
+{
+  if (rtc_on_utc) {
+    return gmtime(t);
+  } else {
+    return localtime(t);
+  }
+}
+
+/* ================================================== */
+
+/* Inverse function to get back from RTC 'DMY HMS' form to time_t UTC
+   form.  This essentially uses mktime(), but involves some awful
+   complexity to cope with timezones.  The problem is that mktime's
+   behaviour with regard to the daylight saving flag in the 'struct
+   tm' does not seem to be reliable across all systems, unless that
+   flag is set to zero. 
+
+   tm_isdst = -1 does not seem to work with all libc's - it is treated
+   as meaning there is DST, or fails completely.  (It is supposed to
+   use the timezone info to work out whether summer time is active at
+   the specified epoch).
+
+   tm_isdst = 1 fails if the local timezone has no summer time defined.
+
+   The approach taken is as follows.  Suppose the RTC is on localtime.
+   We perform all mktime calls with the tm_isdst field set to zero.
+
+   Let y be the RTC reading in 'DMY HMS' form.  Let M be the mktime
+   function with tm_isdst=0 and L be the localtime function.
+
+   We seek x such that y = L(x).  Now there will exist a value Z(t)
+   such that M(L(t)) = t + Z(t) for all t, where Z(t) depends on
+   whether daylight saving is active at time t.
+
+   We want L(x) = y.  Therefore M(L(x)) = x + Z = M(y).  But
+   M(L(M(y))) = M(y) + Z.  Therefore x = M(y) - Z = M(y) - (M(L(M(y)))
+   - M(y)).
+
+   The case for the RTC running on UTC is identical but without the
+   potential complication that Z depends on t.
+*/
+
+static time_t
+t_from_rtc(struct tm *stm) {
+  struct tm temp1, temp2, *tm;
+  long diff;
+  time_t t1, t2;
+
+  temp1 = *stm;
+  temp1.tm_isdst = 0;
+  
+  t1 = mktime(&temp1);
+
+  tm = rtc_on_utc ? gmtime(&t1) : localtime(&t1);
+  if (!tm) {
+    DEBUG_LOG("gmtime()/localtime() failed");
+    return -1;
+  }
+
+  temp2 = *tm;
+  temp2.tm_isdst = 0;
+  t2 = mktime(&temp2);
+  diff = t2 - t1;
+
+  if (t1 - diff == -1)
+    DEBUG_LOG("Could not convert RTC time");
+
+  return t1 - diff;
+}
+
+/* ================================================== */
+
+static void
+read_hwclock_file(const char *hwclock_file)
+{
+  FILE *in;
+  char line[256];
+  int i;
+
+  if (!hwclock_file || !hwclock_file[0])
+    return;
+
+  in = UTI_OpenFile(NULL, hwclock_file, NULL, 'r', 0);
+  if (!in)
+    return;
+
+  /* Read third line from the file. */
+  for (i = 0; i < 3; i++) {
+    if (!fgets(line, sizeof(line), in))
+      break;
+  }
+
+  fclose(in);
+
+  if (i == 3 && !strncmp(line, "LOCAL", 5)) {
+    rtc_on_utc = 0;
+  } else if (i == 3 && !strncmp(line, "UTC", 3)) {
+    rtc_on_utc = 1;
+  } else {
+    LOG(LOGS_WARN, "Could not read RTC LOCAL/UTC setting from %s", hwclock_file);
+  }
+}
+
+/* ================================================== */
+
+static void
+setup_config(void)
+{
+  if (CNF_GetRtcOnUtc()) {
+    rtc_on_utc = 1;
+  } else {
+    rtc_on_utc = 0;
+  }
+
+  read_hwclock_file(CNF_GetHwclockFile());
+
+  autotrim_threshold = CNF_GetRtcAutotrim();
+}
+
+/* ================================================== */
+/* Read the coefficients from the file where they were saved
+   the last time the program was run. */
+
+static void
+read_coefs_from_file(void)
+{
+  double ref_time;
+  FILE *in;
+
+  if (!tried_to_load_coefs) {
+
+    valid_coefs_from_file = 0; /* only gets set true if we succeed */
+
+    tried_to_load_coefs = 1;
+
+    if (coefs_file_name &&
+        (in = UTI_OpenFile(NULL, coefs_file_name, NULL, 'r', 0))) {
+      if (fscanf(in, "%d%lf%lf%lf",
+                 &valid_coefs_from_file,
+                 &ref_time,
+                 &file_ref_offset,
+                 &file_rate_ppm) == 4) {
+        file_ref_time = ref_time;
+      } else {
+        LOG(LOGS_WARN, "Could not read coefficients from %s", coefs_file_name);
+      }
+      fclose(in);
+    }
+  }
+}
+
+/* ================================================== */
+/* Write the coefficients to the file where they will be read
+   the next time the program is run. */
+
+static int
+write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
+{
+  FILE *out;
+
+  /* Create a temporary file with a '.tmp' extension. */
+  out = UTI_OpenFile(NULL, coefs_file_name, ".tmp", 'w', 0644);
+  if (!out)
+    return RTC_ST_BADFILE;
+
+  /* Gain rate is written out in ppm */
+  fprintf(out, "%1d %.0f %.6f %.3f\n", valid, (double)ref_time, offset, 1.0e6 * rate);
+  fclose(out);
+
+  /* Rename the temporary file to the correct location */
+  if (!UTI_RenameTempFile(NULL, coefs_file_name, ".tmp", NULL))
+    return RTC_ST_BADFILE;
+
+  return RTC_ST_OK;
+}
+
+/* ================================================== */
+
+static int
+switch_interrupts(int on_off)
+{
+  if (ioctl(fd, on_off ? RTC_UIE_ON : RTC_UIE_OFF, 0) < 0) {
+    LOG(LOGS_ERR, "Could not %s RTC interrupt : %s",
+        on_off ? "enable" : "disable", strerror(errno));
+    return 0;
+  }
+
+  if (on_off)
+    skip_interrupts = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+/* file_name is the name of the file where we save the RTC params
+   between executions.  Return status is whether we could initialise
+   on this version of the system. */
+
+int
+RTC_Linux_Initialise(void)
+{
+  /* Try to open the device */
+  fd = open(CNF_GetRtcDevice(), O_RDWR);
+  if (fd < 0) {
+    LOG(LOGS_ERR, "Could not open RTC device %s : %s",
+        CNF_GetRtcDevice(), strerror(errno));
+    return 0;
+  }
+
+  /* Make sure the RTC supports interrupts */
+  if (!switch_interrupts(1) || !switch_interrupts(0)) {
+    close(fd);
+    return 0;
+  }
+
+  /* Close on exec */
+  UTI_FdSetCloexec(fd);
+
+  rtc_sec = MallocArray(time_t, MAX_SAMPLES);
+  system_times = MallocArray(struct timespec, MAX_SAMPLES);
+
+  /* Setup details depending on configuration options */
+  setup_config();
+
+  /* In case it didn't get done by pre-init */
+  coefs_file_name = CNF_GetRtcFile();
+
+  n_samples = 0;
+  n_samples_since_regression = 0;
+  n_runs = 0;
+  coefs_valid = 0;
+
+  measurement_period = LOWEST_MEASUREMENT_PERIOD;
+
+  operating_mode = OM_NORMAL;
+
+  /* Register file handler */
+  SCH_AddFileHandler(fd, SCH_FILE_INPUT, read_from_device, NULL);
+
+  /* Register slew handler */
+  LCL_AddParameterChangeHandler(slew_samples, NULL);
+
+  logfileid = CNF_GetLogRtc() ? LOG_FileOpen("rtc",
+      "   Date (UTC) Time   RTC fast (s) Val   Est fast (s)   Slope (ppm)  Ns  Nr Meas")
+    : -1;
+  return 1;
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_Finalise(void)
+{
+  SCH_RemoveTimeout(timeout_id);
+  timeout_id = 0;
+
+  /* Remove input file handler */
+  if (fd >= 0) {
+    SCH_RemoveFileHandler(fd);
+    switch_interrupts(0);
+    close(fd);
+
+    /* Save the RTC data */
+    (void) RTC_Linux_WriteParameters();
+
+  }
+
+  if (rtc_sec)
+    LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+
+  Free(rtc_sec);
+  Free(system_times);
+}
+
+/* ================================================== */
+
+static void
+measurement_timeout(void *any)
+{
+  timeout_id = 0;
+  switch_interrupts(1);
+}
+
+/* ================================================== */
+
+static void
+set_rtc(time_t new_rtc_time)
+{
+  struct tm rtc_tm;
+  struct rtc_time rtc_raw;
+  int status;
+
+  rtc_tm = *rtc_from_t(&new_rtc_time);
+
+  rtc_raw.tm_sec = rtc_tm.tm_sec;
+  rtc_raw.tm_min = rtc_tm.tm_min;
+  rtc_raw.tm_hour = rtc_tm.tm_hour;
+  rtc_raw.tm_mday = rtc_tm.tm_mday;
+  rtc_raw.tm_mon = rtc_tm.tm_mon;
+  rtc_raw.tm_year = rtc_tm.tm_year;
+  rtc_raw.tm_wday = rtc_tm.tm_wday;
+  rtc_raw.tm_yday = rtc_tm.tm_yday;
+  rtc_raw.tm_isdst = rtc_tm.tm_isdst;
+
+  status = ioctl(fd, RTC_SET_TIME, &rtc_raw);
+  if (status < 0) {
+    LOG(LOGS_ERR, "Could not set RTC time");
+  }
+
+}
+
+/* ================================================== */
+
+static void
+handle_initial_trim(void)
+{
+  double rate;
+  long delta_time;
+  double rtc_error_now, sys_error_now;
+
+    /* The idea is to accumulate some number of samples at 1 second
+       intervals, then do a robust regression fit to this.  This
+       should give a good fix on the intercept (=system clock error
+       rel to RTC) at a particular time, removing risk of any
+       particular sample being an outlier.  We can then look at the
+       elapsed interval since the epoch recorded in the RTC file,
+       and correct the system time accordingly. */
+    
+  run_regression(1, &coefs_valid, &coef_ref_time, &coef_seconds_fast, &coef_gain_rate);
+
+  n_samples_since_regression = 0;
+  n_samples = 0;
+
+  read_coefs_from_file();
+
+  if (valid_coefs_from_file) {
+    /* Can process data */
+    delta_time = coef_ref_time - file_ref_time;
+    rate = 1.0e-6 * file_rate_ppm;
+    rtc_error_now = file_ref_offset + rate * (double) delta_time;
+          
+    /* sys_error_now is positive if the system clock is fast */
+    sys_error_now = rtc_error_now - coef_seconds_fast;
+          
+    LCL_AccumulateOffset(sys_error_now, 0.0);
+    LOG(LOGS_INFO, "System clock off from RTC by %f seconds (slew)",
+        sys_error_now);
+  } else {
+    LOG(LOGS_WARN, "No valid rtcfile coefficients");
+  }
+  
+  coefs_valid = 0;
+  
+  (after_init_hook)(after_init_hook_arg);
+  
+  operating_mode = OM_NORMAL;
+}
+
+/* ================================================== */
+
+static void
+handle_relock_after_trim(void)
+{
+  int valid;
+  time_t ref;
+  double fast, slope;
+
+  valid = 0;
+  run_regression(1, &valid, &ref, &fast, &slope);
+
+  if (valid) {
+    write_coefs_to_file(1,ref,fast,saved_coef_gain_rate);
+  } else {
+    DEBUG_LOG("Could not do regression after trim");
+  }
+
+  coefs_valid = 0;
+  n_samples = 0;
+  n_samples_since_regression = 0;
+  operating_mode = OM_NORMAL;
+  measurement_period = LOWEST_MEASUREMENT_PERIOD;
+}
+
+/* ================================================== */
+
+static void
+maybe_autotrim(void)
+{
+  /* Trim only when in normal mode, the coefficients are fresh, the current
+     offset is above the threshold and the system clock is synchronized */
+
+  if (operating_mode != OM_NORMAL || !coefs_valid || n_samples_since_regression)
+    return;
+  
+  if (autotrim_threshold <= 0.0 || fabs(coef_seconds_fast) < autotrim_threshold)
+    return;
+
+  if (REF_GetOurStratum() >= 16)
+    return;
+
+  RTC_Linux_Trim();
+}
+
+/* ================================================== */
+
+static void
+process_reading(time_t rtc_time, struct timespec *system_time)
+{
+  double rtc_fast;
+
+  accumulate_sample(rtc_time, system_time);
+
+  switch (operating_mode) {
+    case OM_NORMAL:
+
+      if (n_samples_since_regression >= N_SAMPLES_PER_REGRESSION) {
+        run_regression(1, &coefs_valid, &coef_ref_time, &coef_seconds_fast, &coef_gain_rate);
+        n_samples_since_regression = 0;
+        maybe_autotrim();
+      }
+      
+      break;
+    case OM_INITIAL:
+      if (n_samples_since_regression >= 8) {
+        handle_initial_trim();
+      }
+      break;
+    case OM_AFTERTRIM:
+      if (n_samples_since_regression >= 8) {
+        handle_relock_after_trim();
+      }
+      break;
+    default:
+      assert(0);
+      break;
+  }  
+
+
+  if (logfileid != -1) {
+    rtc_fast = (rtc_time - system_time->tv_sec) - 1.0e-9 * system_time->tv_nsec;
+
+    LOG_FileWrite(logfileid, "%s %14.6f %1d  %14.6f  %12.3f  %2d  %2d %4d",
+            UTI_TimeToLogForm(system_time->tv_sec),
+            rtc_fast,
+            coefs_valid,
+            coef_seconds_fast, coef_gain_rate * 1.0e6, n_samples, n_runs, measurement_period);
+  }    
+
+}
+
+/* ================================================== */
+
+static void
+read_from_device(int fd_, int event, void *any)
+{
+  int status;
+  unsigned long data;
+  struct timespec sys_time;
+  struct rtc_time rtc_raw;
+  struct tm rtc_tm;
+  time_t rtc_t;
+  int error = 0;
+
+  status = read(fd, &data, sizeof(data));
+
+  if (status < 0) {
+    /* This looks like a bad error : the file descriptor was indicating it was
+     * ready to read but we couldn't read anything.  Give up. */
+    LOG(LOGS_ERR, "Could not read flags %s : %s", CNF_GetRtcDevice(), strerror(errno));
+    SCH_RemoveFileHandler(fd);
+    switch_interrupts(0); /* Likely to raise error too, but just to be sure... */
+    close(fd);
+    fd = -1;
+    return;
+  }    
+
+  if (skip_interrupts > 0) {
+    /* Wait for the next interrupt, this one may be bogus */
+    skip_interrupts--;
+    return;
+  }
+
+  if ((data & RTC_UF) == RTC_UF) {
+    /* Update interrupt detected */
+    
+    /* Read RTC time, sandwiched between two polls of the system clock
+       so we can bound any error. */
+
+    SCH_GetLastEventTime(&sys_time, NULL, NULL);
+
+    status = ioctl(fd, RTC_RD_TIME, &rtc_raw);
+    if (status < 0) {
+      LOG(LOGS_ERR, "Could not read time from %s : %s", CNF_GetRtcDevice(), strerror(errno));
+      error = 1;
+      goto turn_off_interrupt;
+    }
+
+    /* Convert RTC time into a struct timespec */
+    rtc_tm.tm_sec = rtc_raw.tm_sec;
+    rtc_tm.tm_min = rtc_raw.tm_min;
+    rtc_tm.tm_hour = rtc_raw.tm_hour;
+    rtc_tm.tm_mday = rtc_raw.tm_mday;
+    rtc_tm.tm_mon = rtc_raw.tm_mon;
+    rtc_tm.tm_year = rtc_raw.tm_year;
+
+    rtc_t = t_from_rtc(&rtc_tm);
+
+    if (rtc_t == (time_t)(-1)) {
+      error = 1;
+      goto turn_off_interrupt;
+    }      
+
+    process_reading(rtc_t, &sys_time);
+
+    if (n_samples < 4) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD;
+    } else if (n_samples < 6) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 1;
+    } else if (n_samples < 10) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 2;
+    } else if (n_samples < 14) {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 3;
+    } else {
+      measurement_period = LOWEST_MEASUREMENT_PERIOD << 4;
+    }
+
+  }
+
+turn_off_interrupt:
+
+  switch (operating_mode) {
+    case OM_INITIAL:
+      if (error) {
+        DEBUG_LOG("Could not complete initial step due to errors");
+        operating_mode = OM_NORMAL;
+        (after_init_hook)(after_init_hook_arg);
+
+        switch_interrupts(0);
+    
+        timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+      }
+
+      break;
+
+    case OM_AFTERTRIM:
+      if (error) {
+        DEBUG_LOG("Could not complete after trim relock due to errors");
+        operating_mode = OM_NORMAL;
+
+        switch_interrupts(0);
+    
+        timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+      }
+      
+      break;
+
+    case OM_NORMAL:
+      switch_interrupts(0);
+    
+      timeout_id = SCH_AddTimeoutByDelay((double) measurement_period, measurement_timeout, NULL);
+
+      break;
+    default:
+      assert(0);
+      break;
+  }
+
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_TimeInit(void (*after_hook)(void *), void *anything)
+{
+  after_init_hook = after_hook;
+  after_init_hook_arg = anything;
+
+  operating_mode = OM_INITIAL;
+  timeout_id = 0;
+  switch_interrupts(1);
+}
+
+/* ================================================== */
+
+void
+RTC_Linux_StartMeasurements(void)
+{
+  measurement_timeout(NULL);
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_WriteParameters(void)
+{
+  int retval;
+
+  if (fd < 0) {
+    return RTC_ST_NODRV;
+  }
+  
+  if (coefs_valid) {
+    retval = write_coefs_to_file(1,coef_ref_time, coef_seconds_fast, coef_gain_rate);
+  } else {
+   /* Don't change the existing file, it may not be 100% valid but is our
+      current best guess. */
+    retval = RTC_ST_OK; /*write_coefs_to_file(0,0,0.0,0.0); */
+  }
+
+  return(retval);
+}
+
+/* ================================================== */
+/* Try to set the system clock from the RTC, in the same manner as
+   /sbin/hwclock -s would do.  We're not as picky about OS version
+   etc in this case, since we have fewer requirements regarding the
+   RTC behaviour than we do for the rest of the module. */
+
+int
+RTC_Linux_TimePreInit(time_t driftfile_time)
+{
+  int fd, status;
+  struct rtc_time rtc_raw, rtc_raw_retry;
+  struct tm rtc_tm;
+  time_t rtc_t;
+  double accumulated_error, sys_offset;
+  struct timespec new_sys_time, old_sys_time;
+
+  coefs_file_name = CNF_GetRtcFile();
+
+  setup_config();
+  read_coefs_from_file();
+
+  fd = open(CNF_GetRtcDevice(), O_RDONLY);
+
+  if (fd < 0) {
+    return 0; /* Can't open it, and won't be able to later */
+  }
+
+  /* Retry reading the rtc until both read attempts give the same sec value.
+     This way the race condition is prevented that the RTC has updated itself
+     during the first read operation. */
+  do {
+    status = ioctl(fd, RTC_RD_TIME, &rtc_raw);
+    if (status >= 0) {
+      status = ioctl(fd, RTC_RD_TIME, &rtc_raw_retry);
+    }
+  } while (status >= 0 && rtc_raw.tm_sec != rtc_raw_retry.tm_sec);
+
+  /* Read system clock */
+  LCL_ReadCookedTime(&old_sys_time, NULL);
+
+  close(fd);
+
+  if (status >= 0) {
+    /* Convert to seconds since 1970 */
+    rtc_tm.tm_sec = rtc_raw.tm_sec;
+    rtc_tm.tm_min = rtc_raw.tm_min;
+    rtc_tm.tm_hour = rtc_raw.tm_hour;
+    rtc_tm.tm_mday = rtc_raw.tm_mday;
+    rtc_tm.tm_mon = rtc_raw.tm_mon;
+    rtc_tm.tm_year = rtc_raw.tm_year;
+    
+    rtc_t = t_from_rtc(&rtc_tm);
+
+    if (rtc_t != (time_t)(-1)) {
+
+      /* Work out approximatation to correct time (to about the
+         nearest second) */
+      if (valid_coefs_from_file) {
+        accumulated_error = file_ref_offset +
+          (rtc_t - file_ref_time) * 1.0e-6 * file_rate_ppm;
+      } else {
+        accumulated_error = 0.0;
+      }
+
+      /* Correct time */
+
+      new_sys_time.tv_sec = rtc_t;
+      /* Average error in the RTC reading */
+      new_sys_time.tv_nsec = 500000000;
+
+      UTI_AddDoubleToTimespec(&new_sys_time, -accumulated_error, &new_sys_time);
+
+      if (new_sys_time.tv_sec < driftfile_time) {
+        LOG(LOGS_WARN, "RTC time before last driftfile modification (ignored)");
+        return 0;
+      }
+
+      sys_offset = UTI_DiffTimespecsToDouble(&old_sys_time, &new_sys_time);
+
+      /* Set system time only if the step is larger than 1 second */
+      if (fabs(sys_offset) >= 1.0) {
+        if (LCL_ApplyStepOffset(sys_offset))
+          LOG(LOGS_INFO, "System time set from RTC");
+      }
+    } else {
+      return 0;
+    }
+  } else {
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_GetReport(RPT_RTC_Report *report)
+{
+  report->ref_time.tv_sec = coef_ref_time;
+  report->ref_time.tv_nsec = 0;
+  report->n_samples = n_samples;
+  report->n_runs = n_runs;
+  if (n_samples > 1) {
+    report->span_seconds = rtc_sec[n_samples - 1] - rtc_sec[0];
+  } else {
+    report->span_seconds = 0;
+  }
+  report->rtc_seconds_fast = coef_seconds_fast;
+  report->rtc_gain_rate_ppm = 1.0e6 * coef_gain_rate;
+  return 1;
+}
+
+/* ================================================== */
+
+int
+RTC_Linux_Trim(void)
+{
+  struct timespec now;
+
+  /* Remember the slope coefficient - we won't be able to determine a
+     good one in a few seconds when we determine the new offset! */
+  saved_coef_gain_rate = coef_gain_rate;
+
+  if (fabs(coef_seconds_fast) > 1.0) {
+
+    LOG(LOGS_INFO, "RTC wrong by %.3f seconds (step)",
+        coef_seconds_fast);
+
+    /* Do processing to set clock.  Let R be the value we set the
+       RTC to, then in 500ms the RTC ticks (R+1) (see comments in
+       arch/i386/kernel/time.c about the behaviour of the real time
+       clock chip).  If S is the system time now, the error at the
+       next RTC tick is given by E = (R+1) - (S+0.5).  Ideally we
+       want |E| <= 0.5, which implies R <= S <= R+1, i.e. R is just
+       the rounded down part of S, i.e. the seconds part. */
+
+    LCL_ReadCookedTime(&now, NULL);
+    
+    set_rtc(now.tv_sec);
+
+    /* All old samples will now look bogus under the new
+           regime. */
+    n_samples = 0;
+    operating_mode = OM_AFTERTRIM;
+
+    /* Estimate the offset in case writertc is called or chronyd
+       is terminated during rapid sampling */
+    coef_seconds_fast = -now.tv_nsec / 1.0e9 + 0.5;
+    coef_ref_time = now.tv_sec;
+
+    /* And start rapid sampling, interrupts on now */
+    SCH_RemoveTimeout(timeout_id);
+    timeout_id = 0;
+    switch_interrupts(1);
+  }
+
+  return 1;
+  
+}
diff --git a/rtc_linux.h b/rtc_linux.h
new file mode 100644
index 0000000..fa33ef1
--- /dev/null
+++ b/rtc_linux.h
@@ -0,0 +1,45 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  ======================================================================
+
+  */
+
+#ifndef _GOT_RTC_LINUX_H
+#define _GOT_RTC_LINUX_H
+
+#include "reports.h"
+
+extern int RTC_Linux_Initialise(void);
+extern void RTC_Linux_Finalise(void);
+extern int RTC_Linux_TimePreInit(time_t driftile_time);
+extern void RTC_Linux_TimeInit(void (*after_hook)(void *), void *anything);
+extern void RTC_Linux_StartMeasurements(void);
+
+/* 0=success, 1=no driver, 2=can't write file */
+extern int RTC_Linux_WriteParameters(void);
+
+extern int RTC_Linux_GetReport(RPT_RTC_Report *report);
+extern int RTC_Linux_Trim(void);
+
+extern void RTC_Linux_CycleLogFile(void);
+
+#endif /* _GOT_RTC_LINUX_H */
diff --git a/samplefilt.c b/samplefilt.c
new file mode 100644
index 0000000..9b81a76
--- /dev/null
+++ b/samplefilt.c
@@ -0,0 +1,497 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2009-2011, 2014, 2016, 2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing a median sample filter.
+
+  */
+
+#include "config.h"
+
+#include "local.h"
+#include "logging.h"
+#include "memory.h"
+#include "regress.h"
+#include "samplefilt.h"
+#include "util.h"
+
+#define MIN_SAMPLES 1
+#define MAX_SAMPLES 256
+
+struct SPF_Instance_Record {
+  int min_samples;
+  int max_samples;
+  int index;
+  int used;
+  int last;
+  int avg_var_n;
+  double avg_var;
+  double max_var;
+  double combine_ratio;
+  NTP_Sample *samples;
+  int *selected;
+  double *x_data;
+  double *y_data;
+  double *w_data;
+};
+
+/* ================================================== */
+
+SPF_Instance
+SPF_CreateInstance(int min_samples, int max_samples, double max_dispersion, double combine_ratio)
+{
+  SPF_Instance filter;
+
+  filter = MallocNew(struct SPF_Instance_Record);
+
+  min_samples = CLAMP(MIN_SAMPLES, min_samples, MAX_SAMPLES);
+  max_samples = CLAMP(MIN_SAMPLES, max_samples, MAX_SAMPLES);
+  max_samples = MAX(min_samples, max_samples);
+  combine_ratio = CLAMP(0.0, combine_ratio, 1.0);
+
+  filter->min_samples = min_samples;
+  filter->max_samples = max_samples;
+  filter->index = -1;
+  filter->used = 0;
+  filter->last = -1;
+  /* Set the first estimate to the system precision */
+  filter->avg_var_n = 0;
+  filter->avg_var = SQUARE(LCL_GetSysPrecisionAsQuantum());
+  filter->max_var = SQUARE(max_dispersion);
+  filter->combine_ratio = combine_ratio;
+  filter->samples = MallocArray(NTP_Sample, filter->max_samples);
+  filter->selected = MallocArray(int, filter->max_samples);
+  filter->x_data = MallocArray(double, filter->max_samples);
+  filter->y_data = MallocArray(double, filter->max_samples);
+  filter->w_data = MallocArray(double, filter->max_samples);
+
+  return filter;
+}
+
+/* ================================================== */
+
+void
+SPF_DestroyInstance(SPF_Instance filter)
+{
+  Free(filter->samples);
+  Free(filter->selected);
+  Free(filter->x_data);
+  Free(filter->y_data);
+  Free(filter->w_data);
+  Free(filter);
+}
+
+/* ================================================== */
+
+/* Check that samples times are strictly increasing */
+
+static int
+check_sample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (filter->used <= 0)
+    return 1;
+
+  if (UTI_CompareTimespecs(&filter->samples[filter->last].time, &sample->time) >= 0) {
+    DEBUG_LOG("filter non-increasing sample time %s", UTI_TimespecToString(&sample->time));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_AccumulateSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (!check_sample(filter, sample))
+      return 0;
+
+  filter->index++;
+  filter->index %= filter->max_samples;
+  filter->last = filter->index;
+  if (filter->used < filter->max_samples)
+    filter->used++;
+
+  filter->samples[filter->index] = *sample;
+
+  DEBUG_LOG("filter sample %d t=%s offset=%.9f peer_disp=%.9f",
+            filter->index, UTI_TimespecToString(&sample->time),
+            sample->offset, sample->peer_dispersion);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetLastSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  if (filter->last < 0)
+    return 0;
+
+  *sample = filter->samples[filter->last];
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetNumberOfSamples(SPF_Instance filter)
+{
+  return filter->used;
+}
+
+/* ================================================== */
+
+int
+SPF_GetMaxSamples(SPF_Instance filter)
+{
+  return filter->max_samples;
+}
+
+/* ================================================== */
+
+double
+SPF_GetAvgSampleDispersion(SPF_Instance filter)
+{
+  return sqrt(filter->avg_var);
+}
+
+/* ================================================== */
+
+static void
+drop_samples(SPF_Instance filter, int keep_last)
+{
+  filter->index = -1;
+  filter->used = 0;
+  if (!keep_last)
+    filter->last = -1;
+}
+
+/* ================================================== */
+
+void
+SPF_DropSamples(SPF_Instance filter)
+{
+  drop_samples(filter, 0);
+}
+
+/* ================================================== */
+
+static const NTP_Sample *tmp_sort_samples;
+
+static int
+compare_samples(const void *a, const void *b)
+{
+  const NTP_Sample *s1, *s2;
+
+  s1 = &tmp_sort_samples[*(int *)a];
+  s2 = &tmp_sort_samples[*(int *)b];
+
+  if (s1->offset < s2->offset)
+    return -1;
+  else if (s1->offset > s2->offset)
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+select_samples(SPF_Instance filter)
+{
+  int i, j, k, o, from, to, *selected;
+  double min_dispersion;
+
+  if (filter->used < filter->min_samples)
+    return 0;
+
+  selected = filter->selected;
+
+  /* With 4 or more samples, select those that have peer dispersion smaller
+     than 1.5x of the minimum dispersion */
+  if (filter->used > 4) {
+    for (i = 1, min_dispersion = filter->samples[0].peer_dispersion; i < filter->used; i++) {
+      if (min_dispersion > filter->samples[i].peer_dispersion)
+        min_dispersion = filter->samples[i].peer_dispersion;
+    }
+
+    for (i = j = 0; i < filter->used; i++) {
+      if (filter->samples[i].peer_dispersion <= 1.5 * min_dispersion)
+        selected[j++] = i;
+    }
+  } else {
+    j = 0;
+  }
+
+  if (j < 4) {
+    /* Select all samples */
+
+    for (j = 0; j < filter->used; j++)
+      selected[j] = j;
+  }
+
+  /* And sort their indices by offset */
+  tmp_sort_samples = filter->samples;
+  qsort(selected, j, sizeof (int), compare_samples);
+
+  /* Select samples closest to the median */
+  if (j > 2) {
+    from = j * (1.0 - filter->combine_ratio) / 2.0;
+    from = CLAMP(1, from, (j - 1) / 2);
+  } else {
+    from = 0;
+  }
+
+  to = j - from;
+
+  /* Mark unused samples and sort the rest by their time */
+
+  o = filter->used - filter->index - 1;
+
+  for (i = 0; i < from; i++)
+    selected[i] = -1;
+  for (; i < to; i++)
+    selected[i] = (selected[i] + o) % filter->used;
+  for (; i < filter->used; i++)
+    selected[i] = -1;
+
+  for (i = from; i < to; i++) {
+    j = selected[i];
+    selected[i] = -1;
+    while (j != -1 && selected[j] != j) {
+      k = selected[j];
+      selected[j] = j;
+      j = k;
+    }
+  }
+
+  for (i = j = 0; i < filter->used; i++) {
+    if (selected[i] != -1)
+      selected[j++] = (selected[i] + filter->used - o) % filter->used;
+  }
+
+  assert(j > 0 && j <= filter->max_samples);
+
+  return j;
+}
+
+/* ================================================== */
+
+static int
+combine_selected_samples(SPF_Instance filter, int n, NTP_Sample *result)
+{
+  double mean_peer_dispersion, mean_root_dispersion, mean_peer_delay, mean_root_delay;
+  double mean_x, mean_y, disp, var, prev_avg_var;
+  NTP_Sample *sample, *last_sample;
+  int i, dof;
+
+  last_sample = &filter->samples[filter->selected[n - 1]];
+
+  /* Prepare data */
+  for (i = 0; i < n; i++) {
+    sample = &filter->samples[filter->selected[i]];
+
+    filter->x_data[i] = UTI_DiffTimespecsToDouble(&sample->time, &last_sample->time);
+    filter->y_data[i] = sample->offset;
+    filter->w_data[i] = sample->peer_dispersion;
+  }
+
+  /* Calculate mean offset and interval since the last sample */
+  for (i = 0, mean_x = mean_y = 0.0; i < n; i++) {
+    mean_x += filter->x_data[i];
+    mean_y += filter->y_data[i];
+  }
+  mean_x /= n;
+  mean_y /= n;
+
+  if (n >= 4) {
+    double b0, b1, s2, sb0, sb1;
+
+    /* Set y axis to the mean sample time */
+    for (i = 0; i < n; i++)
+      filter->x_data[i] -= mean_x;
+
+    /* Make a linear fit and use the estimated standard deviation of the
+       intercept as dispersion */
+    RGR_WeightedRegression(filter->x_data, filter->y_data, filter->w_data, n,
+                           &b0, &b1, &s2, &sb0, &sb1);
+    var = s2;
+    disp = sb0;
+    dof = n - 2;
+  } else if (n >= 2) {
+    for (i = 0, disp = 0.0; i < n; i++)
+      disp += (filter->y_data[i] - mean_y) * (filter->y_data[i] - mean_y);
+    var = disp / (n - 1);
+    disp = sqrt(var);
+    dof = n - 1;
+  } else {
+    var = filter->avg_var;
+    disp = sqrt(var);
+    dof = 1;
+  }
+
+  /* Avoid working with zero dispersion */
+  if (var < 1e-20) {
+    var = 1e-20;
+    disp = sqrt(var);
+  }
+
+  /* Drop the sample if the variance is larger than the maximum */
+  if (filter->max_var > 0.0 && var > filter->max_var) {
+    DEBUG_LOG("filter dispersion too large disp=%.9f max=%.9f",
+              sqrt(var), sqrt(filter->max_var));
+    return 0;
+  }
+
+  prev_avg_var = filter->avg_var;
+
+  /* Update the exponential moving average of the variance */
+  if (filter->avg_var_n > 50) {
+    filter->avg_var += dof / (dof + 50.0) * (var - filter->avg_var);
+  } else {
+    filter->avg_var = (filter->avg_var * filter->avg_var_n + var * dof) /
+      (dof + filter->avg_var_n);
+    if (filter->avg_var_n == 0)
+      prev_avg_var = filter->avg_var;
+    filter->avg_var_n += dof;
+  }
+
+  /* Use the long-term average of variance instead of the estimated value
+     unless it is significantly smaller in order to reduce the noise in
+     sourcestats weights */
+  if (var * dof / RGR_GetChi2Coef(dof) < prev_avg_var)
+    disp = sqrt(filter->avg_var) * disp / sqrt(var);
+
+  mean_peer_dispersion = mean_root_dispersion = mean_peer_delay = mean_root_delay = 0.0;
+
+  for (i = 0; i < n; i++) {
+    sample = &filter->samples[filter->selected[i]];
+
+    mean_peer_dispersion += sample->peer_dispersion;
+    mean_root_dispersion += sample->root_dispersion;
+    mean_peer_delay += sample->peer_delay;
+    mean_root_delay += sample->root_delay;
+  }
+
+  mean_peer_dispersion /= n;
+  mean_root_dispersion /= n;
+  mean_peer_delay /= n;
+  mean_root_delay /= n;
+
+  UTI_AddDoubleToTimespec(&last_sample->time, mean_x, &result->time);
+  result->offset = mean_y;
+  result->peer_dispersion = MAX(disp, mean_peer_dispersion);
+  result->root_dispersion = MAX(disp, mean_root_dispersion);
+  result->peer_delay = mean_peer_delay;
+  result->root_delay = mean_root_delay;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SPF_GetFilteredSample(SPF_Instance filter, NTP_Sample *sample)
+{
+  int n;
+
+  n = select_samples(filter);
+
+  DEBUG_LOG("selected %d from %d samples", n, filter->used);
+
+  if (n < 1)
+    return 0;
+
+  if (!combine_selected_samples(filter, n, sample))
+    return 0;
+
+  drop_samples(filter, 1);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+get_first_last(SPF_Instance filter, int *first, int *last)
+{
+  if (filter->last < 0)
+    return 0;
+
+  /* Always slew the last sample as it may be returned even if no new
+     samples were accumulated */
+  if (filter->used > 0) {
+    *first = 0;
+    *last = filter->used - 1;
+  } else {
+    *first = *last = filter->last;
+  }
+
+  return 1;
+}
+
+
+/* ================================================== */
+
+void
+SPF_SlewSamples(SPF_Instance filter, struct timespec *when, double dfreq, double doffset)
+{
+  int i, first, last;
+  double delta_time;
+
+  if (!get_first_last(filter, &first, &last))
+    return;
+
+  for (i = first; i <= last; i++) {
+    UTI_AdjustTimespec(&filter->samples[i].time, when, &filter->samples[i].time,
+                       &delta_time, dfreq, doffset);
+    filter->samples[i].offset -= delta_time;
+  }
+}
+
+/* ================================================== */
+
+void
+SPF_CorrectOffset(SPF_Instance filter, double doffset)
+{
+  int i, first, last;
+
+  if (!get_first_last(filter, &first, &last))
+    return;
+
+  for (i = first; i <= last; i++)
+    filter->samples[i].offset -= doffset;
+}
+
+/* ================================================== */
+
+void
+SPF_AddDispersion(SPF_Instance filter, double dispersion)
+{
+  int i;
+
+  for (i = 0; i < filter->used; i++) {
+    filter->samples[i].peer_dispersion += dispersion;
+    filter->samples[i].root_dispersion += dispersion;
+  }
+}
diff --git a/samplefilt.h b/samplefilt.h
new file mode 100644
index 0000000..8d72b85
--- /dev/null
+++ b/samplefilt.h
@@ -0,0 +1,51 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for sample filter.
+
+  */
+
+#ifndef GOT_SAMPLEFILT_H
+#define GOT_SAMPLEFILT_H
+
+#include "ntp.h"
+
+typedef struct SPF_Instance_Record *SPF_Instance;
+
+extern SPF_Instance SPF_CreateInstance(int min_samples, int max_samples,
+                                       double max_dispersion, double combine_ratio);
+extern void SPF_DestroyInstance(SPF_Instance filter);
+
+extern int SPF_AccumulateSample(SPF_Instance filter, NTP_Sample *sample);
+extern int SPF_GetLastSample(SPF_Instance filter, NTP_Sample *sample);
+extern int SPF_GetNumberOfSamples(SPF_Instance filter);
+extern int SPF_GetMaxSamples(SPF_Instance filter);
+extern double SPF_GetAvgSampleDispersion(SPF_Instance filter);
+extern void SPF_DropSamples(SPF_Instance filter);
+extern int SPF_GetFilteredSample(SPF_Instance filter, NTP_Sample *sample);
+extern void SPF_SlewSamples(SPF_Instance filter, struct timespec *when,
+                            double dfreq, double doffset);
+extern void SPF_CorrectOffset(SPF_Instance filter, double doffset);
+extern void SPF_AddDispersion(SPF_Instance filter, double dispersion);
+
+#endif
diff --git a/sched.c b/sched.c
new file mode 100644
index 0000000..676866e
--- /dev/null
+++ b/sched.c
@@ -0,0 +1,866 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011, 2013-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains the scheduling loop and the timeout queue.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "array.h"
+#include "sched.h"
+#include "memory.h"
+#include "util.h"
+#include "local.h"
+#include "logging.h"
+
+/* ================================================== */
+
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* ================================================== */
+
+/* One more than the highest file descriptor that is registered */
+static unsigned int one_highest_fd;
+
+#ifndef FD_SETSIZE
+/* If FD_SETSIZE is not defined, assume that fd_set is implemented
+   as a fixed size array of bits, possibly embedded inside a record */
+#define FD_SETSIZE (sizeof(fd_set) * 8)
+#endif
+
+typedef struct {
+  SCH_FileHandler       handler;
+  SCH_ArbitraryArgument arg;
+  int                   events;
+} FileHandlerEntry;
+
+static ARR_Instance file_handlers;
+
+/* Timestamp when last select() returned */
+static struct timespec last_select_ts, last_select_ts_raw;
+static double last_select_ts_err;
+
+#define TS_MONO_PRECISION_NS 10000000U
+
+/* Monotonic low-precision timestamp measuring interval since the start */
+static double last_select_ts_mono;
+static uint32_t last_select_ts_mono_ns;
+
+/* ================================================== */
+
+/* Variables to handler the timer queue */
+
+typedef struct _TimerQueueEntry
+{
+  struct _TimerQueueEntry *next; /* Forward and back links in the list */
+  struct _TimerQueueEntry *prev;
+  struct timespec ts;           /* Local system time at which the
+                                   timeout is to expire.  Clearly this
+                                   must be in terms of what the
+                                   operating system thinks of as
+                                   system time, because it will be an
+                                   argument to select().  Therefore,
+                                   any fudges etc that our local time
+                                   driver module would apply to time
+                                   that we pass to clients etc doesn't
+                                   apply to this. */
+  SCH_TimeoutID id;             /* ID to allow client to delete
+                                   timeout */
+  SCH_TimeoutClass class;       /* The class that the epoch is in */
+  SCH_TimeoutHandler handler;   /* The handler routine to use */
+  SCH_ArbitraryArgument arg;    /* The argument to pass to the handler */
+
+} TimerQueueEntry;
+
+/* The timer queue.  We only use the next and prev entries of this
+   record, these chain to the real entries. */
+static TimerQueueEntry timer_queue;
+static unsigned long n_timer_queue_entries;
+static SCH_TimeoutID next_tqe_id;
+
+/* Pointer to head of free list */
+static TimerQueueEntry *tqe_free_list;
+
+/* Array of all allocated tqe blocks to be freed in finalisation */
+static ARR_Instance tqe_blocks;
+
+/* Timestamp when was last timeout dispatched for each class */
+static struct timespec last_class_dispatch[SCH_NumberOfClasses];
+
+/* ================================================== */
+
+/* Flag terminating the main loop, which can be set from a signal handler */
+static volatile int need_to_exit;
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything);
+
+/* ================================================== */
+
+void
+SCH_Initialise(void)
+{
+  file_handlers = ARR_CreateInstance(sizeof (FileHandlerEntry));
+
+  n_timer_queue_entries = 0;
+  next_tqe_id = 0;
+  tqe_free_list = NULL;
+  tqe_blocks = ARR_CreateInstance(sizeof (TimerQueueEntry *));
+
+  timer_queue.next = &timer_queue;
+  timer_queue.prev = &timer_queue;
+
+  need_to_exit = 0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+
+  LCL_ReadRawTime(&last_select_ts_raw);
+  last_select_ts = last_select_ts_raw;
+  last_select_ts_mono = 0.0;
+  last_select_ts_mono_ns = 0;
+
+  initialised = 1;
+}
+
+
+/* ================================================== */
+
+void
+SCH_Finalise(void) {
+  unsigned int i;
+
+  ARR_DestroyInstance(file_handlers);
+
+  timer_queue.next = &timer_queue;
+  timer_queue.prev = &timer_queue;
+  for (i = 0; i < ARR_GetSize(tqe_blocks); i++)
+    Free(*(TimerQueueEntry **)ARR_GetElement(tqe_blocks, i));
+  ARR_DestroyInstance(tqe_blocks);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+void
+SCH_AddFileHandler
+(int fd, int events, SCH_FileHandler handler, SCH_ArbitraryArgument arg)
+{
+  FileHandlerEntry *ptr;
+
+  assert(initialised);
+  assert(events);
+  assert(fd >= 0);
+  
+  if (fd >= FD_SETSIZE)
+    LOG_FATAL("Too many file descriptors");
+
+  /* Resize the array if the descriptor is highest so far */
+  while (ARR_GetSize(file_handlers) <= fd) {
+    ptr = ARR_GetNewElement(file_handlers);
+    ptr->handler = NULL;
+    ptr->arg = NULL;
+    ptr->events = 0;
+  }
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  /* Don't want to allow the same fd to register a handler more than
+     once without deleting a previous association - this suggests
+     a bug somewhere else in the program. */
+  assert(!ptr->handler);
+
+  ptr->handler = handler;
+  ptr->arg = arg;
+  ptr->events = events;
+
+  if (one_highest_fd < fd + 1)
+    one_highest_fd = fd + 1;
+}
+
+
+/* ================================================== */
+
+void
+SCH_RemoveFileHandler(int fd)
+{
+  FileHandlerEntry *ptr;
+
+  assert(initialised);
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  /* Check that a handler was registered for the fd in question */
+  assert(ptr->handler);
+
+  ptr->handler = NULL;
+  ptr->arg = NULL;
+  ptr->events = 0;
+
+  /* Find new highest file descriptor */
+  while (one_highest_fd > 0) {
+    ptr = ARR_GetElement(file_handlers, one_highest_fd - 1);
+    if (ptr->handler)
+      break;
+    one_highest_fd--;
+  }
+}
+
+/* ================================================== */
+
+void
+SCH_SetFileHandlerEvent(int fd, int event, int enable)
+{
+  FileHandlerEntry *ptr;
+
+  ptr = ARR_GetElement(file_handlers, fd);
+
+  if (enable)
+    ptr->events |= event;
+  else
+    ptr->events &= ~event;
+}
+
+/* ================================================== */
+
+void
+SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw)
+{
+  if (cooked) {
+    *cooked = last_select_ts;
+    if (err)
+      *err = last_select_ts_err;
+  }
+  if (raw)
+    *raw = last_select_ts_raw;
+}
+
+/* ================================================== */
+
+double
+SCH_GetLastEventMonoTime(void)
+{
+  return last_select_ts_mono;
+}
+
+/* ================================================== */
+
+#define TQE_ALLOC_QUANTUM 32
+
+static TimerQueueEntry *
+allocate_tqe(void)
+{
+  TimerQueueEntry *new_block;
+  TimerQueueEntry *result;
+  int i;
+  if (tqe_free_list == NULL) {
+    new_block = MallocArray(TimerQueueEntry, TQE_ALLOC_QUANTUM);
+    for (i=1; i<TQE_ALLOC_QUANTUM; i++) {
+      new_block[i].next = &(new_block[i-1]);
+    }
+    new_block[0].next = NULL;
+    tqe_free_list = &(new_block[TQE_ALLOC_QUANTUM - 1]);
+    ARR_AppendElement(tqe_blocks, &new_block);
+  }
+
+  result = tqe_free_list;
+  tqe_free_list = tqe_free_list->next;
+  return result;
+}
+
+/* ================================================== */
+
+static void
+release_tqe(TimerQueueEntry *node)
+{
+  node->next = tqe_free_list;
+  tqe_free_list = node;
+}
+
+/* ================================================== */
+
+static SCH_TimeoutID
+get_new_tqe_id(void)
+{
+  TimerQueueEntry *ptr;
+
+try_again:
+  next_tqe_id++;
+  if (!next_tqe_id)
+    goto try_again;
+
+  /* Make sure the ID isn't already used */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next)
+    if (ptr->id == next_tqe_id)
+      goto try_again;
+
+  return next_tqe_id;
+}
+
+/* ================================================== */
+
+SCH_TimeoutID
+SCH_AddTimeout(struct timespec *ts, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  TimerQueueEntry *new_tqe;
+  TimerQueueEntry *ptr;
+
+  assert(initialised);
+
+  new_tqe = allocate_tqe();
+
+  new_tqe->id = get_new_tqe_id();
+  new_tqe->handler = handler;
+  new_tqe->arg = arg;
+  new_tqe->ts = *ts;
+  new_tqe->class = SCH_ReservedTimeoutValue;
+
+  /* Now work out where to insert the new entry in the list */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    if (UTI_CompareTimespecs(&new_tqe->ts, &ptr->ts) == -1) {
+      /* If the new entry comes before the current pointer location in
+         the list, we want to insert the new entry just before ptr. */
+      break;
+    }
+  }
+
+  /* At this stage, we want to insert the new entry immediately before
+     the entry identified by 'ptr' */
+
+  new_tqe->next = ptr;
+  new_tqe->prev = ptr->prev;
+  ptr->prev->next = new_tqe;
+  ptr->prev = new_tqe;
+
+  n_timer_queue_entries++;
+
+  return new_tqe->id;
+}
+
+/* ================================================== */
+/* This queues a timeout to elapse at a given delta time relative to
+   the current (raw) time */
+
+SCH_TimeoutID
+SCH_AddTimeoutByDelay(double delay, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  struct timespec now, then;
+
+  assert(initialised);
+  assert(delay >= 0.0);
+
+  LCL_ReadRawTime(&now);
+  UTI_AddDoubleToTimespec(&now, delay, &then);
+  if (UTI_CompareTimespecs(&now, &then) > 0) {
+    LOG_FATAL("Timeout overflow");
+  }
+
+  return SCH_AddTimeout(&then, handler, arg);
+
+}
+
+/* ================================================== */
+
+SCH_TimeoutID
+SCH_AddTimeoutInClass(double min_delay, double separation, double randomness,
+                      SCH_TimeoutClass class,
+                      SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  TimerQueueEntry *new_tqe;
+  TimerQueueEntry *ptr;
+  struct timespec now;
+  double diff, r;
+  double new_min_delay;
+
+  assert(initialised);
+  assert(min_delay >= 0.0);
+  assert(class < SCH_NumberOfClasses);
+
+  if (randomness > 0.0) {
+    uint32_t rnd;
+
+    UTI_GetRandomBytes(&rnd, sizeof (rnd));
+    r = rnd * (randomness / (uint32_t)-1) + 1.0;
+    min_delay *= r;
+    separation *= r;
+  }
+  
+  LCL_ReadRawTime(&now);
+  new_min_delay = min_delay;
+
+  /* Check the separation from the last dispatched timeout */
+  diff = UTI_DiffTimespecsToDouble(&now, &last_class_dispatch[class]);
+  if (diff < separation && diff >= 0.0 && diff + new_min_delay < separation) {
+    new_min_delay = separation - diff;
+  }
+
+  /* Scan through list for entries in the same class and increase min_delay
+     if necessary to keep at least the separation away */
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    if (ptr->class == class) {
+      diff = UTI_DiffTimespecsToDouble(&ptr->ts, &now);
+      if (new_min_delay > diff) {
+        if (new_min_delay - diff < separation) {
+          new_min_delay = diff + separation;
+        }
+      } else {
+        if (diff - new_min_delay < separation) {
+          new_min_delay = diff + separation;
+        }
+      }
+    }
+  }
+
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+    diff = UTI_DiffTimespecsToDouble(&ptr->ts, &now);
+    if (diff > new_min_delay) {
+      break;
+    }
+  }
+
+  /* We have located the insertion point */
+  new_tqe = allocate_tqe();
+
+  new_tqe->id = get_new_tqe_id();
+  new_tqe->handler = handler;
+  new_tqe->arg = arg;
+  UTI_AddDoubleToTimespec(&now, new_min_delay, &new_tqe->ts);
+  new_tqe->class = class;
+
+  new_tqe->next = ptr;
+  new_tqe->prev = ptr->prev;
+  ptr->prev->next = new_tqe;
+  ptr->prev = new_tqe;
+  n_timer_queue_entries++;
+
+  return new_tqe->id;
+}
+
+/* ================================================== */
+
+void
+SCH_RemoveTimeout(SCH_TimeoutID id)
+{
+  TimerQueueEntry *ptr;
+
+  assert(initialised);
+
+  if (!id)
+    return;
+
+  for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+
+    if (ptr->id == id) {
+      /* Found the required entry */
+      
+      /* Unlink from the queue */
+      ptr->next->prev = ptr->prev;
+      ptr->prev->next = ptr->next;
+      
+      /* Decrement entry count */
+      --n_timer_queue_entries;
+      
+      /* Release memory back to the operating system */
+      release_tqe(ptr);
+
+      return;
+    }
+  }
+
+  /* Catch calls with invalid non-zero ID */
+  assert(0);
+}
+
+/* ================================================== */
+/* Try to dispatch any timeouts that have already gone by, and
+   keep going until all are done.  (The earlier ones may take so
+   long to do that the later ones come around by the time they are
+   completed). */
+
+static void
+dispatch_timeouts(struct timespec *now) {
+  unsigned long n_done, n_entries_on_start;
+  TimerQueueEntry *ptr;
+  SCH_TimeoutHandler handler;
+  SCH_ArbitraryArgument arg;
+
+  n_entries_on_start = n_timer_queue_entries;
+  n_done = 0;
+
+  do {
+    LCL_ReadRawTime(now);
+
+    if (!(n_timer_queue_entries > 0 &&
+          UTI_CompareTimespecs(now, &timer_queue.next->ts) >= 0)) {
+      break;
+    }
+
+    ptr = timer_queue.next;
+
+    last_class_dispatch[ptr->class] = *now;
+
+    handler = ptr->handler;
+    arg = ptr->arg;
+
+    SCH_RemoveTimeout(ptr->id);
+
+    /* Dispatch the handler */
+    (handler)(arg);
+
+    /* Increment count of timeouts handled */
+    ++n_done;
+
+    /* If the number of dispatched timeouts is significantly larger than the
+       length of the queue on start and now, assume there is a bug causing
+       an infinite loop by constantly adding a timeout with a zero or negative
+       delay.  Check the actual rate of timeouts to avoid false positives in
+       case the execution slowed down so much (e.g. due to memory thrashing)
+       that it repeatedly takes more time to handle the timeout than is its
+       delay.  This is a safety mechanism intended to stop a full-speed flood
+       of NTP requests due to a bug in the NTP polling. */
+
+    if (n_done > 20 &&
+        n_done > 4 * MAX(n_timer_queue_entries, n_entries_on_start) &&
+        fabs(UTI_DiffTimespecsToDouble(now, &last_select_ts_raw)) / n_done < 0.01)
+      LOG_FATAL("Possible infinite loop in scheduling");
+
+  } while (!need_to_exit);
+}
+
+/* ================================================== */
+
+/* nfd is the number of bits set in all fd_sets */
+
+static void
+dispatch_filehandlers(int nfd, fd_set *read_fds, fd_set *write_fds, fd_set *except_fds)
+{
+  FileHandlerEntry *ptr;
+  int fd;
+  
+  for (fd = 0; nfd && fd < one_highest_fd; fd++) {
+    if (except_fds && FD_ISSET(fd, except_fds)) {
+      /* This descriptor has an exception, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_EXCEPTION, ptr->arg);
+      nfd--;
+
+      /* Don't try to read from it now */
+      if (read_fds && FD_ISSET(fd, read_fds)) {
+        FD_CLR(fd, read_fds);
+        nfd--;
+      }
+    }
+
+    if (read_fds && FD_ISSET(fd, read_fds)) {
+      /* This descriptor can be read from, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_INPUT, ptr->arg);
+      nfd--;
+    }
+
+    if (write_fds && FD_ISSET(fd, write_fds)) {
+      /* This descriptor can be written to, dispatch its handler */
+      ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
+      if (ptr->handler)
+        (ptr->handler)(fd, SCH_FILE_OUTPUT, ptr->arg);
+      nfd--;
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw,
+            struct timespec *cooked,
+            double dfreq,
+            double doffset,
+            LCL_ChangeType change_type,
+            void *anything)
+{
+  TimerQueueEntry *ptr;
+  double delta;
+  int i;
+
+  if (change_type != LCL_ChangeAdjust) {
+    /* Make sure this handler is invoked first in order to not shift new timers
+       added from other handlers */
+    assert(LCL_IsFirstParameterChangeHandler(handle_slew));
+
+    /* If a step change occurs, just shift all raw time stamps by the offset */
+    
+    for (ptr = timer_queue.next; ptr != &timer_queue; ptr = ptr->next) {
+      UTI_AddDoubleToTimespec(&ptr->ts, -doffset, &ptr->ts);
+    }
+
+    for (i = 0; i < SCH_NumberOfClasses; i++) {
+      UTI_AddDoubleToTimespec(&last_class_dispatch[i], -doffset, &last_class_dispatch[i]);
+    }
+
+    UTI_AddDoubleToTimespec(&last_select_ts_raw, -doffset, &last_select_ts_raw);
+  }
+
+  UTI_AdjustTimespec(&last_select_ts, cooked, &last_select_ts, &delta, dfreq, doffset);
+}
+
+/* ================================================== */
+
+static void
+fill_fd_sets(fd_set **read_fds, fd_set **write_fds, fd_set **except_fds)
+{
+  FileHandlerEntry *handlers;
+  fd_set *rd, *wr, *ex;
+  int i, n, events;
+
+  n = ARR_GetSize(file_handlers);
+  handlers = ARR_GetElements(file_handlers);
+  rd = wr = ex = NULL;
+
+  for (i = 0; i < n; i++) {
+    events = handlers[i].events;
+
+    if (!events)
+      continue;
+
+    if (events & SCH_FILE_INPUT) {
+      if (!rd) {
+        rd = *read_fds;
+        FD_ZERO(rd);
+      }
+      FD_SET(i, rd);
+    }
+
+    if (events & SCH_FILE_OUTPUT) {
+      if (!wr) {
+        wr = *write_fds;
+        FD_ZERO(wr);
+      }
+      FD_SET(i, wr);
+    }
+
+    if (events & SCH_FILE_EXCEPTION) {
+      if (!ex) {
+        ex = *except_fds;
+        FD_ZERO(ex);
+      }
+      FD_SET(i, ex);
+    }
+  }
+
+  if (!rd)
+    *read_fds = NULL;
+  if (!wr)
+    *write_fds = NULL;
+  if (!ex)
+    *except_fds = NULL;
+}
+
+/* ================================================== */
+
+#define JUMP_DETECT_THRESHOLD 10
+
+static int
+check_current_time(struct timespec *prev_raw, struct timespec *raw, int timeout,
+                   struct timeval *orig_select_tv,
+                   struct timeval *rem_select_tv)
+{
+  struct timespec elapsed_min, elapsed_max, orig_select_ts, rem_select_ts;
+  double step, elapsed;
+
+  UTI_TimevalToTimespec(orig_select_tv, &orig_select_ts);
+
+  /* Get an estimate of the time spent waiting in the select() call. On some
+     systems (e.g. Linux) the timeout timeval is modified to return the
+     remaining time, use that information. */
+  if (timeout) {
+    elapsed_max = elapsed_min = orig_select_ts;
+  } else if (rem_select_tv && rem_select_tv->tv_sec >= 0 &&
+             rem_select_tv->tv_sec <= orig_select_tv->tv_sec &&
+             (rem_select_tv->tv_sec != orig_select_tv->tv_sec ||
+              rem_select_tv->tv_usec != orig_select_tv->tv_usec)) {
+    UTI_TimevalToTimespec(rem_select_tv, &rem_select_ts);
+    UTI_DiffTimespecs(&elapsed_min, &orig_select_ts, &rem_select_ts);
+    elapsed_max = elapsed_min;
+  } else {
+    if (rem_select_tv)
+      elapsed_max = orig_select_ts;
+    else
+      UTI_DiffTimespecs(&elapsed_max, raw, prev_raw);
+    UTI_ZeroTimespec(&elapsed_min);
+  }
+
+  if (last_select_ts_raw.tv_sec + elapsed_min.tv_sec >
+      raw->tv_sec + JUMP_DETECT_THRESHOLD) {
+    LOG(LOGS_WARN, "Backward time jump detected!");
+  } else if (prev_raw->tv_sec + elapsed_max.tv_sec + JUMP_DETECT_THRESHOLD <
+             raw->tv_sec) {
+    LOG(LOGS_WARN, "Forward time jump detected!");
+  } else {
+    return 1;
+  }
+
+  step = UTI_DiffTimespecsToDouble(&last_select_ts_raw, raw);
+  elapsed = UTI_TimespecToDouble(&elapsed_min);
+  step += elapsed;
+
+  /* Cooked time may no longer be valid after dispatching the handlers */
+  LCL_NotifyExternalTimeStep(raw, raw, step, fabs(step));
+
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+update_monotonic_time(struct timespec *now, struct timespec *before)
+{
+  struct timespec diff;
+
+  /* Avoid frequent floating-point operations and handle small
+     increments to a large value */
+
+  UTI_DiffTimespecs(&diff, now, before);
+  if (diff.tv_sec == 0) {
+    last_select_ts_mono_ns += diff.tv_nsec;
+  } else {
+    last_select_ts_mono += fabs(UTI_TimespecToDouble(&diff) +
+                                last_select_ts_mono_ns / 1.0e9);
+    last_select_ts_mono_ns = 0;
+  }
+
+  if (last_select_ts_mono_ns > TS_MONO_PRECISION_NS) {
+    last_select_ts_mono += last_select_ts_mono_ns / 1.0e9;
+    last_select_ts_mono_ns = 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCH_MainLoop(void)
+{
+  fd_set read_fds, write_fds, except_fds;
+  fd_set *p_read_fds, *p_write_fds, *p_except_fds;
+  int status, errsv;
+  struct timeval tv, saved_tv, *ptv;
+  struct timespec ts, now, saved_now, cooked;
+  double err;
+
+  assert(initialised);
+
+  while (!need_to_exit) {
+    /* Dispatch timeouts and fill now with current raw time */
+    dispatch_timeouts(&now);
+    saved_now = now;
+    
+    /* The timeout handlers may request quit */
+    if (need_to_exit)
+      break;
+
+    /* Check whether there is a timeout and set it up */
+    if (n_timer_queue_entries > 0) {
+      UTI_DiffTimespecs(&ts, &timer_queue.next->ts, &now);
+      assert(ts.tv_sec > 0 || ts.tv_nsec > 0);
+
+      UTI_TimespecToTimeval(&ts, &tv);
+      ptv = &tv;
+      saved_tv = tv;
+    } else {
+      ptv = NULL;
+      saved_tv.tv_sec = saved_tv.tv_usec = 0;
+    }
+
+    p_read_fds = &read_fds;
+    p_write_fds = &write_fds;
+    p_except_fds = &except_fds;
+    fill_fd_sets(&p_read_fds, &p_write_fds, &p_except_fds);
+
+    /* if there are no file descriptors being waited on and no
+       timeout set, this is clearly ridiculous, so stop the run */
+    if (!ptv && !p_read_fds && !p_write_fds)
+      LOG_FATAL("Nothing to do");
+
+    status = select(one_highest_fd, p_read_fds, p_write_fds, p_except_fds, ptv);
+    errsv = errno;
+
+    LCL_ReadRawTime(&now);
+    LCL_CookTime(&now, &cooked, &err);
+
+    update_monotonic_time(&now, &last_select_ts_raw);
+
+    /* Check if the time didn't jump unexpectedly */
+    if (!check_current_time(&saved_now, &now, status == 0, &saved_tv, ptv)) {
+      /* Cook the time again after handling the step */
+      LCL_CookTime(&now, &cooked, &err);
+    }
+
+    last_select_ts_raw = now;
+    last_select_ts = cooked;
+    last_select_ts_err = err;
+
+    if (status < 0) {
+      if (!need_to_exit && errsv != EINTR) {
+        LOG_FATAL("select() failed : %s", strerror(errsv));
+      }
+    } else if (status > 0) {
+      /* A file descriptor is ready for input or output */
+      dispatch_filehandlers(status, p_read_fds, p_write_fds, p_except_fds);
+    } else {
+      /* No descriptors readable, timeout must have elapsed.
+       Therefore, tv must be non-null */
+      assert(ptv);
+
+      /* There's nothing to do here, since the timeouts
+         will be dispatched at the top of the next loop
+         cycle */
+
+    }
+  }         
+}
+
+/* ================================================== */
+
+void
+SCH_QuitProgram(void)
+{
+  need_to_exit = 1;
+}
+
+/* ================================================== */
+
diff --git a/sched.h b/sched.h
new file mode 100644
index 0000000..90d757f
--- /dev/null
+++ b/sched.h
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Exported header file for sched.c
+  */
+
+#ifndef GOT_SCHED_H
+#define GOT_SCHED_H
+
+#include "sysincl.h"
+
+/* Type for timeout IDs, valid IDs are always greater than zero */
+typedef unsigned int SCH_TimeoutID;
+
+typedef enum {
+  SCH_ReservedTimeoutValue = 0,
+  SCH_NtpClientClass,
+  SCH_NtpPeerClass,
+  SCH_NtpBroadcastClass,
+  SCH_PhcPollClass,
+  SCH_NumberOfClasses /* needs to be last */
+} SCH_TimeoutClass;
+
+typedef void* SCH_ArbitraryArgument;
+typedef void (*SCH_FileHandler)(int fd, int event, SCH_ArbitraryArgument);
+typedef void (*SCH_TimeoutHandler)(SCH_ArbitraryArgument);
+
+/* Exported functions */
+
+/* Initialisation function for the module */
+extern void SCH_Initialise(void);
+
+/* Finalisation function for the module */
+extern void SCH_Finalise(void);
+
+/* File events */
+#define SCH_FILE_INPUT 1
+#define SCH_FILE_OUTPUT 2
+#define SCH_FILE_EXCEPTION 4
+
+/* Register a handler for when select goes true on a file descriptor */
+extern void SCH_AddFileHandler(int fd, int events, SCH_FileHandler handler, SCH_ArbitraryArgument arg);
+extern void SCH_RemoveFileHandler(int fd);
+extern void SCH_SetFileHandlerEvent(int fd, int event, int enable);
+
+/* Get the time stamp taken after a file descriptor became ready or a timeout expired */
+extern void SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw);
+
+/* Get a low-precision monotonic timestamp (starting at 0.0) */
+extern double SCH_GetLastEventMonoTime(void);
+
+/* This queues a timeout to elapse at a given (raw) local time */
+extern SCH_TimeoutID SCH_AddTimeout(struct timespec *ts, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg);
+
+/* This queues a timeout to elapse at a given delta time relative to the current (raw) time */
+extern SCH_TimeoutID SCH_AddTimeoutByDelay(double delay, SCH_TimeoutHandler, SCH_ArbitraryArgument);
+
+/* This queues a timeout in a particular class, ensuring that the
+   expiry time is at least a given separation away from any other
+   timeout in the same class, given randomness is added to the delay
+   and separation */
+extern SCH_TimeoutID SCH_AddTimeoutInClass(double min_delay, double separation, double randomness,
+                                           SCH_TimeoutClass class,
+                                           SCH_TimeoutHandler handler, SCH_ArbitraryArgument);
+
+/* The next one probably ought to return a status code */
+extern void SCH_RemoveTimeout(SCH_TimeoutID);
+
+extern void SCH_MainLoop(void);
+
+extern void SCH_QuitProgram(void);
+
+#endif /* GOT_SCHED_H */
diff --git a/siv.h b/siv.h
new file mode 100644
index 0000000..868edbd
--- /dev/null
+++ b/siv.h
@@ -0,0 +1,74 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for Synthetic Initialization Vector (SIV) ciphers.
+
+  */
+
+#ifndef GOT_SIV_H
+#define GOT_SIV_H
+
+/* Maximum key length of all supported SIVs */
+#define SIV_MAX_KEY_LENGTH 32
+
+/* Maximum difference between lengths of ciphertext and plaintext */
+#define SIV_MAX_TAG_LENGTH 16
+
+/* Identifiers of SIV algorithms following the IANA AEAD registry */
+typedef enum {
+  AEAD_AES_SIV_CMAC_256 = 15,
+  AEAD_AES_SIV_CMAC_384 = 16,
+  AEAD_AES_SIV_CMAC_512 = 17,
+  AEAD_AES_128_GCM_SIV = 30,
+  AEAD_AES_256_GCM_SIV = 31,
+} SIV_Algorithm;
+
+typedef struct SIV_Instance_Record *SIV_Instance;
+
+extern SIV_Instance SIV_CreateInstance(SIV_Algorithm algorithm);
+
+extern void SIV_DestroyInstance(SIV_Instance instance);
+
+extern int SIV_GetKeyLength(SIV_Algorithm algorithm);
+
+extern int SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length);
+
+extern int SIV_GetMinNonceLength(SIV_Instance instance);
+
+extern int SIV_GetMaxNonceLength(SIV_Instance instance);
+
+extern int SIV_GetTagLength(SIV_Instance instance);
+
+extern int SIV_Encrypt(SIV_Instance instance,
+                       const unsigned char *nonce, int nonce_length,
+                       const void *assoc, int assoc_length,
+                       const void *plaintext, int plaintext_length,
+                       unsigned char *ciphertext, int ciphertext_length);
+
+extern int SIV_Decrypt(SIV_Instance instance,
+                       const unsigned char *nonce, int nonce_length,
+                       const void *assoc, int assoc_length,
+                       const unsigned char *ciphertext, int ciphertext_length,
+                       void *plaintext, int plaintext_length);
+
+#endif
diff --git a/siv_gnutls.c b/siv_gnutls.c
new file mode 100644
index 0000000..95387f0
--- /dev/null
+++ b/siv_gnutls.c
@@ -0,0 +1,287 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  SIV ciphers using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "logging.h"
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+  gnutls_cipher_algorithm_t algorithm;
+  gnutls_aead_cipher_hd_t cipher;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  DEBUG_LOG("Initialised");
+  gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  assert(gnutls_initialised);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_cipher_algorithm_t
+get_cipher_algorithm(SIV_Algorithm algorithm)
+{
+  switch (algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      return GNUTLS_CIPHER_AES_128_SIV;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+  gnutls_cipher_algorithm_t calgo;
+  SIV_Instance instance;
+
+  calgo = get_cipher_algorithm(algorithm);
+  if (calgo == 0)
+    return NULL;
+
+  if (instance_counter == 0)
+    init_gnutls();
+
+  /* Check if the cipher is actually supported */
+  if (gnutls_cipher_get_tag_size(calgo) == 0) {
+    if (instance_counter == 0)
+      deinit_gnutls();
+    return NULL;
+  }
+
+  instance = MallocNew(struct SIV_Instance_Record);
+  instance->algorithm = calgo;
+  instance->cipher = NULL;
+
+  instance_counter++;
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+  if (instance->cipher)
+    gnutls_aead_cipher_deinit(instance->cipher);
+  Free(instance);
+
+  instance_counter--;
+  if (instance_counter == 0)
+    deinit_gnutls();
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+  gnutls_cipher_algorithm_t calgo = get_cipher_algorithm(algorithm);
+  int len;
+
+  if (calgo == 0)
+    return 0;
+
+  len = gnutls_cipher_get_key_size(calgo);
+
+  if (len < 1 || len > SIV_MAX_KEY_LENGTH)
+    LOG_FATAL("Invalid key length");
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+  gnutls_aead_cipher_hd_t cipher;
+  gnutls_datum_t datum;
+  int r;
+
+  if (length <= 0 || length != gnutls_cipher_get_key_size(instance->algorithm))
+    return 0;
+
+  datum.data = (unsigned char *)key;
+  datum.size = length;
+
+#ifdef HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+  if (instance->cipher) {
+    r = gnutls_aead_cipher_set_key(instance->cipher, &datum);
+    if (r < 0) {
+      DEBUG_LOG("Could not set cipher key : %s", gnutls_strerror(r));
+      return 0;
+    }
+
+    return 1;
+  }
+#endif
+
+  /* Initialise a new cipher with the provided key */
+  r = gnutls_aead_cipher_init(&cipher, instance->algorithm, &datum);
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "cipher", gnutls_strerror(r));
+    return 0;
+  }
+
+  /* Destroy the previous cipher (if its key could not be changed directly) */
+  if (instance->cipher)
+    gnutls_aead_cipher_deinit(instance->cipher);
+
+  instance->cipher = cipher;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetMinNonceLength(SIV_Instance instance)
+{
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetMaxNonceLength(SIV_Instance instance)
+{
+  return INT_MAX;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+  int len;
+
+  len = gnutls_cipher_get_tag_size(instance->algorithm);
+
+  if (len < 1 || len > SIV_MAX_TAG_LENGTH)
+    LOG_FATAL("Invalid tag length");
+
+  return len;
+}
+
+/* ================================================== */
+
+int
+SIV_Encrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const void *plaintext, int plaintext_length,
+            unsigned char *ciphertext, int ciphertext_length)
+{
+  size_t clen = ciphertext_length;
+
+  if (!instance->cipher)
+    return 0;
+
+  if (nonce_length < 1 || assoc_length < 0 ||
+      plaintext_length < 0 || ciphertext_length < 0)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (gnutls_aead_cipher_encrypt(instance->cipher,
+                                 nonce, nonce_length, assoc, assoc_length, 0,
+                                 plaintext, plaintext_length, ciphertext, &clen) < 0)
+    return 0;
+
+  if (clen != ciphertext_length)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_Decrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const unsigned char *ciphertext, int ciphertext_length,
+            void *plaintext, int plaintext_length)
+{
+  size_t plen = plaintext_length;
+
+  if (!instance->cipher)
+    return 0;
+
+  if (nonce_length < 1 || assoc_length < 0 ||
+      plaintext_length < 0 || ciphertext_length < 0)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (gnutls_aead_cipher_decrypt(instance->cipher,
+                                 nonce, nonce_length, assoc, assoc_length, 0,
+                                 ciphertext, ciphertext_length, plaintext, &plen) < 0)
+    return 0;
+
+  if (plen != plaintext_length)
+    return 0;
+
+  return 1;
+}
diff --git a/siv_nettle.c b/siv_nettle.c
new file mode 100644
index 0000000..a8cba49
--- /dev/null
+++ b/siv_nettle.c
@@ -0,0 +1,251 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  SIV ciphers using the Nettle library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#ifdef HAVE_NETTLE_SIV_CMAC
+#include <nettle/siv-cmac.h>
+#else
+#include "siv_nettle_int.c"
+#endif
+
+#ifdef HAVE_NETTLE_SIV_GCM
+#include <nettle/siv-gcm.h>
+#endif
+
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+  SIV_Algorithm algorithm;
+  int key_set;
+  int min_nonce_length;
+  int max_nonce_length;
+  int tag_length;
+  union {
+    struct siv_cmac_aes128_ctx cmac_aes128;
+#ifdef HAVE_NETTLE_SIV_GCM
+    struct aes128_ctx aes128;
+#endif
+  } ctx;
+};
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+  SIV_Instance instance;
+
+  if (SIV_GetKeyLength(algorithm) <= 0)
+    return NULL;
+
+  instance = MallocNew(struct SIV_Instance_Record);
+  instance->algorithm = algorithm;
+  instance->key_set = 0;
+
+  switch (algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      instance->min_nonce_length = SIV_MIN_NONCE_SIZE;
+      instance->max_nonce_length = INT_MAX;
+      instance->tag_length = SIV_DIGEST_SIZE;
+      break;
+#ifdef HAVE_NETTLE_SIV_GCM
+    case AEAD_AES_128_GCM_SIV:
+      instance->min_nonce_length = SIV_GCM_NONCE_SIZE;
+      instance->max_nonce_length = SIV_GCM_NONCE_SIZE;
+      instance->tag_length = SIV_GCM_DIGEST_SIZE;
+      break;
+#endif
+    default:
+      assert(0);
+  }
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+  Free(instance);
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+  assert(2 * AES128_KEY_SIZE <= SIV_MAX_KEY_LENGTH);
+
+  switch (algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      return 2 * AES128_KEY_SIZE;
+#ifdef HAVE_NETTLE_SIV_GCM
+    case AEAD_AES_128_GCM_SIV:
+      return AES128_KEY_SIZE;
+#endif
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+  if (length != SIV_GetKeyLength(instance->algorithm))
+    return 0;
+
+  switch (instance->algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      siv_cmac_aes128_set_key(&instance->ctx.cmac_aes128, key);
+      break;
+#ifdef HAVE_NETTLE_SIV_GCM
+    case AEAD_AES_128_GCM_SIV:
+      aes128_set_encrypt_key(&instance->ctx.aes128, key);
+      break;
+#endif
+    default:
+      assert(0);
+  }
+
+  instance->key_set = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetMinNonceLength(SIV_Instance instance)
+{
+  return instance->min_nonce_length;
+}
+
+/* ================================================== */
+
+int
+SIV_GetMaxNonceLength(SIV_Instance instance)
+{
+  return instance->max_nonce_length;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+  if (instance->tag_length < 1 || instance->tag_length > SIV_MAX_TAG_LENGTH)
+    assert(0);
+  return instance->tag_length;
+}
+
+/* ================================================== */
+
+int
+SIV_Encrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const void *plaintext, int plaintext_length,
+            unsigned char *ciphertext, int ciphertext_length)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < instance->min_nonce_length ||
+      nonce_length > instance->max_nonce_length || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_GetTagLength(instance) != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  switch (instance->algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      siv_cmac_aes128_encrypt_message(&instance->ctx.cmac_aes128,
+                                      nonce_length, nonce, assoc_length, assoc,
+                                      ciphertext_length, ciphertext, plaintext);
+      break;
+#ifdef HAVE_NETTLE_SIV_GCM
+    case AEAD_AES_128_GCM_SIV:
+      siv_gcm_aes128_encrypt_message(&instance->ctx.aes128,
+                                     nonce_length, nonce, assoc_length, assoc,
+                                     ciphertext_length, ciphertext, plaintext);
+      break;
+#endif
+    default:
+      assert(0);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_Decrypt(SIV_Instance instance,
+            const unsigned char *nonce, int nonce_length,
+            const void *assoc, int assoc_length,
+            const unsigned char *ciphertext, int ciphertext_length,
+            void *plaintext, int plaintext_length)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < instance->min_nonce_length ||
+      nonce_length > instance->max_nonce_length || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_GetTagLength(instance) != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  switch (instance->algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      if (!siv_cmac_aes128_decrypt_message(&instance->ctx.cmac_aes128,
+                                           nonce_length, nonce, assoc_length, assoc,
+                                           plaintext_length, plaintext, ciphertext))
+        return 0;
+      break;
+#ifdef HAVE_NETTLE_SIV_GCM
+    case AEAD_AES_128_GCM_SIV:
+      if (!siv_gcm_aes128_decrypt_message(&instance->ctx.aes128,
+                                          nonce_length, nonce, assoc_length, assoc,
+                                          plaintext_length, plaintext, ciphertext))
+        return 0;
+      break;
+#endif
+    default:
+      assert(0);
+  }
+
+  return 1;
+}
diff --git a/siv_nettle_int.c b/siv_nettle_int.c
new file mode 100644
index 0000000..714eff6
--- /dev/null
+++ b/siv_nettle_int.c
@@ -0,0 +1,452 @@
+/* This is a single-file implementation of AES-SIV-CMAC-256 based on
+   a patch for GNU Nettle by Nikos Mavrogiannopoulos */
+
+/*
+   AES-CMAC-128 (rfc 4493)
+   Copyright (C) Stefan Metzmacher 2012
+   Copyright (C) Jeremy Allison 2012
+   Copyright (C) Michael Adam 2012
+   Copyright (C) 2017, Red Hat Inc.
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+/* siv-aes128.c, siv-cmac.c, siv.h
+
+   AES-SIV, RFC5297
+   SIV-CMAC, RFC5297
+
+   Copyright (C) 2017 Nikos Mavrogiannopoulos
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+/* cmac.h, siv-cmac.h, cmac-aes128.c
+
+   CMAC mode, as specified in RFC4493
+   SIV-CMAC mode, as specified in RFC5297
+   CMAC using AES128 as the underlying cipher.
+
+   Copyright (C) 2017 Red Hat, Inc.
+
+   Contributed by Nikos Mavrogiannopoulos
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+
+# include "config.h"
+
+#include <assert.h>
+#include <string.h>
+
+#include "nettle/aes.h"
+#include "nettle/ctr.h"
+#include "nettle/macros.h"
+#include "nettle/memxor.h"
+#include "nettle/memops.h"
+
+#include "nettle/nettle-types.h"
+
+/* For SIV, the block size of the block cipher shall be 128 bits. */
+#define SIV_BLOCK_SIZE  16
+#define SIV_DIGEST_SIZE 16
+#define SIV_MIN_NONCE_SIZE 1
+
+/*
+ * SIV mode requires the aad and plaintext when building the IV, which
+ * prevents streaming processing and it incompatible with the AEAD API.
+ */
+
+/* AES_SIV_CMAC_256 */
+struct siv_cmac_aes128_ctx {
+    struct aes128_ctx         cipher;
+    uint8_t s2vk[AES128_KEY_SIZE];
+};
+
+struct cmac128_ctx
+{
+  /* Key */
+  union nettle_block16 K1;
+  union nettle_block16 K2;
+
+  /* MAC state */
+  union nettle_block16 X;
+
+  /* Block buffer */
+  union nettle_block16 block;
+  size_t index;
+};
+
+/* shift one and XOR with 0x87. */
+static void
+_cmac128_block_mulx(union nettle_block16 *dst,
+	   const union nettle_block16 *src)
+{
+  uint64_t b1 = READ_UINT64(src->b);
+  uint64_t b2 = READ_UINT64(src->b+8);
+
+  b1 = (b1 << 1) | (b2 >> 63);
+  b2 <<= 1;
+
+  if (src->b[0] & 0x80)
+    b2 ^= 0x87;
+
+  WRITE_UINT64(dst->b, b1);
+  WRITE_UINT64(dst->b+8, b2);
+}
+
+static void
+cmac128_set_key(struct cmac128_ctx *ctx, const void *cipher,
+		nettle_cipher_func *encrypt)
+{
+  static const uint8_t const_zero[] = {
+    0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00
+  };
+  union nettle_block16 *L = &ctx->block;
+  memset(ctx, 0, sizeof(*ctx));
+
+  /* step 1 - generate subkeys k1 and k2 */
+  encrypt(cipher, 16, L->b, const_zero);
+
+  _cmac128_block_mulx(&ctx->K1, L);
+  _cmac128_block_mulx(&ctx->K2, &ctx->K1);
+}
+
+#define MIN(x,y) ((x)<(y)?(x):(y))
+
+static void
+cmac128_update(struct cmac128_ctx *ctx, const void *cipher,
+	       nettle_cipher_func *encrypt,
+	       size_t msg_len, const uint8_t *msg)
+{
+  union nettle_block16 Y;
+  /*
+   * check if we expand the block
+   */
+  if (ctx->index < 16)
+    {
+      size_t len = MIN(16 - ctx->index, msg_len);
+      memcpy(&ctx->block.b[ctx->index], msg, len);
+      msg += len;
+      msg_len -= len;
+      ctx->index += len;
+    }
+
+  if (msg_len == 0) {
+    /* if it is still the last block, we are done */
+    return;
+  }
+
+  /*
+   * now checksum everything but the last block
+   */
+  memxor3(Y.b, ctx->X.b, ctx->block.b, 16);
+  encrypt(cipher, 16, ctx->X.b, Y.b);
+
+  while (msg_len > 16)
+    {
+      memxor3(Y.b, ctx->X.b, msg, 16);
+      encrypt(cipher, 16, ctx->X.b, Y.b);
+      msg += 16;
+      msg_len -= 16;
+    }
+
+  /*
+   * copy the last block, it will be processed in
+   * cmac128_digest().
+   */
+  memcpy(ctx->block.b, msg, msg_len);
+  ctx->index = msg_len;
+}
+
+static void
+cmac128_digest(struct cmac128_ctx *ctx, const void *cipher,
+	       nettle_cipher_func *encrypt,
+	       unsigned length,
+	       uint8_t *dst)
+{
+  union nettle_block16 Y;
+
+  memset(ctx->block.b+ctx->index, 0, sizeof(ctx->block.b)-ctx->index);
+
+  /* re-use ctx->block for memxor output */
+  if (ctx->index < 16)
+    {
+      ctx->block.b[ctx->index] = 0x80;
+      memxor(ctx->block.b, ctx->K2.b, 16);
+    }
+  else
+    {
+      memxor(ctx->block.b, ctx->K1.b, 16);
+    }
+
+  memxor3(Y.b, ctx->block.b, ctx->X.b, 16);
+
+  assert(length <= 16);
+  if (length == 16)
+    {
+      encrypt(cipher, 16, dst, Y.b);
+    }
+  else
+    {
+      encrypt(cipher, 16, ctx->block.b, Y.b);
+      memcpy(dst, ctx->block.b, length);
+    }
+
+  /* reset state for re-use */
+  memset(&ctx->X, 0, sizeof(ctx->X));
+  ctx->index = 0;
+}
+
+
+#define CMAC128_CTX(type) \
+  { struct cmac128_ctx ctx; type cipher; }
+
+/* NOTE: Avoid using NULL, as we don't include anything defining it. */
+#define CMAC128_SET_KEY(self, set_key, encrypt, cmac_key)	\
+  do {								\
+    (set_key)(&(self)->cipher, (cmac_key));			\
+    if (0) (encrypt)(&(self)->cipher, ~(size_t) 0,		\
+		     (uint8_t *) 0, (const uint8_t *) 0);	\
+    cmac128_set_key(&(self)->ctx, &(self)->cipher,		\
+		(nettle_cipher_func *) (encrypt));		\
+  } while (0)
+
+#define CMAC128_UPDATE(self, encrypt, length, src)		\
+  cmac128_update(&(self)->ctx, &(self)->cipher,			\
+	      (nettle_cipher_func *)encrypt, (length), (src))
+
+#define CMAC128_DIGEST(self, encrypt, length, digest)		\
+  (0 ? (encrypt)(&(self)->cipher, ~(size_t) 0,			\
+		 (uint8_t *) 0, (const uint8_t *) 0)		\
+     : cmac128_digest(&(self)->ctx, &(self)->cipher,		\
+		  (nettle_cipher_func *) (encrypt),		\
+		  (length), (digest)))
+
+struct cmac_aes128_ctx CMAC128_CTX(struct aes128_ctx);
+
+static void
+cmac_aes128_set_key(struct cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+  CMAC128_SET_KEY(ctx, aes128_set_encrypt_key, aes128_encrypt, key);
+}
+
+static void
+cmac_aes128_update (struct cmac_aes128_ctx *ctx,
+		   size_t length, const uint8_t *data)
+{
+  CMAC128_UPDATE (ctx, aes128_encrypt, length, data);
+}
+
+static void
+cmac_aes128_digest(struct cmac_aes128_ctx *ctx,
+		  size_t length, uint8_t *digest)
+{
+  CMAC128_DIGEST(ctx, aes128_encrypt, length, digest);
+}
+
+static const uint8_t const_one[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x01
+};
+
+static const uint8_t const_zero[] = {
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00
+};
+
+static
+void _siv_s2v(nettle_set_key_func *cmac_set_key,
+	      nettle_hash_update_func *cmac_update,
+	      nettle_hash_digest_func *cmac_digest,
+	      size_t cmac_ctx_size,
+	      const uint8_t *s2vk, size_t alength, const uint8_t *adata,
+              size_t nlength, const uint8_t *nonce,
+              size_t plength, const uint8_t *pdata,
+              uint8_t *v)
+{
+  uint8_t ctx[sizeof(struct cmac128_ctx)+sizeof(struct aes_ctx)];
+  union nettle_block16 D, S, T;
+
+  assert(cmac_ctx_size <= sizeof (ctx));
+
+  cmac_set_key(ctx, s2vk);
+
+  if (nlength == 0 && alength == 0) {
+    cmac_update(ctx, 16, const_one);
+    cmac_digest(ctx, 16, v);
+    return;
+  }
+
+  cmac_update(ctx, 16, const_zero);
+  cmac_digest(ctx, 16, D.b);
+
+  if (1) {
+    _cmac128_block_mulx(&D, &D);
+    cmac_update(ctx, alength, adata);
+    cmac_digest(ctx, 16, S.b);
+
+    memxor(D.b, S.b, 16);
+  }
+
+  if (nlength > 0) {
+    _cmac128_block_mulx(&D, &D);
+    cmac_update(ctx, nlength, nonce);
+    cmac_digest(ctx, 16, S.b);
+
+    memxor(D.b, S.b, 16);
+  }
+
+  /* Sn */
+  if (plength >= 16) {
+    cmac_update(ctx, plength-16, pdata);
+
+    pdata += plength-16;
+
+    memxor3(T.b, pdata, D.b, 16);
+  } else {
+    union nettle_block16 pad;
+
+    _cmac128_block_mulx(&T, &D);
+    memcpy(pad.b, pdata, plength);
+    pad.b[plength] = 0x80;
+    if (plength+1 < 16)
+      memset(&pad.b[plength+1], 0, 16-plength-1);
+
+    memxor(T.b, pad.b, 16);
+  }
+
+  cmac_update(ctx, 16, T.b);
+  cmac_digest(ctx, 16, v);
+}
+
+static void
+siv_cmac_aes128_set_key(struct siv_cmac_aes128_ctx *ctx, const uint8_t *key)
+{
+  memcpy(ctx->s2vk, key, 16);
+  aes128_set_encrypt_key(&ctx->cipher, key+16);
+}
+
+static void
+siv_cmac_aes128_encrypt_message(struct siv_cmac_aes128_ctx *ctx,
+				size_t nlength, const uint8_t *nonce,
+				size_t alength, const uint8_t *adata,
+				size_t clength, uint8_t *dst, const uint8_t *src)
+{
+  union nettle_block16 siv;
+  size_t slength;
+
+  assert (clength >= SIV_DIGEST_SIZE);
+  slength = clength - SIV_DIGEST_SIZE;
+
+  /* create CTR nonce */
+  _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+	   (nettle_hash_update_func*)cmac_aes128_update,
+	   (nettle_hash_digest_func*)cmac_aes128_digest,
+	   sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+	   nlength, nonce, slength, src, siv.b);
+  memcpy(dst, siv.b, SIV_DIGEST_SIZE);
+  siv.b[8] &= ~0x80;
+  siv.b[12] &= ~0x80;
+
+  ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+            siv.b, slength, dst+SIV_DIGEST_SIZE, src);
+}
+
+static int
+siv_cmac_aes128_decrypt_message(struct siv_cmac_aes128_ctx *ctx,
+				size_t nlength, const uint8_t *nonce,
+				size_t alength, const uint8_t *adata,
+				size_t mlength, uint8_t *dst, const uint8_t *src)
+{
+  union nettle_block16 siv;
+  union nettle_block16 ctr;
+
+  memcpy(ctr.b, src, SIV_DIGEST_SIZE);
+  ctr.b[8] &= ~0x80;
+  ctr.b[12] &= ~0x80;
+
+  ctr_crypt(&ctx->cipher, (nettle_cipher_func *)aes128_encrypt, AES_BLOCK_SIZE,
+            ctr.b, mlength, dst, src+SIV_DIGEST_SIZE);
+
+  /* create CTR nonce */
+  _siv_s2v((nettle_set_key_func*)cmac_aes128_set_key,
+	   (nettle_hash_update_func*)cmac_aes128_update,
+	   (nettle_hash_digest_func*)cmac_aes128_digest,
+	   sizeof(struct cmac_aes128_ctx), ctx->s2vk, alength, adata,
+	   nlength, nonce, mlength, dst, siv.b);
+
+  return memeql_sec(siv.b, src, SIV_DIGEST_SIZE);
+}
+
diff --git a/smooth.c b/smooth.c
new file mode 100644
index 0000000..ee7094e
--- /dev/null
+++ b/smooth.c
@@ -0,0 +1,370 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing time smoothing.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "reference.h"
+#include "smooth.h"
+#include "util.h"
+
+/*
+  Time smoothing determines an offset that needs to be applied to the cooked
+  time to make it smooth for external observers.  Observed offset and frequency
+  change slowly and there are no discontinuities.  This can be used on an NTP
+  server to make it easier for the clients to track the time and keep their
+  clocks close together even when large offset or frequency corrections are
+  applied to the server's clock (e.g. after being offline for longer time).
+
+  Accumulated offset and frequency are smoothed out in three stages.  In the
+  first stage, the frequency is changed at a constant rate (wander) up to a
+  maximum, in the second stage the frequency stays at the maximum for as long
+  as needed and in the third stage the frequency is brought back to zero.
+
+              |
+    max_freq  +-------/--------\-------------
+              |      /|        |\
+        freq  |     / |        | \
+              |    /  |        |  \
+              |   /   |        |   \
+           0  +--/----+--------+----\--------
+              | /     |        |    |    time
+              |/      |        |    |
+
+        stage     1       2      3
+
+  Integral of this function is the smoothed out offset.  It's a continuous
+  piecewise polynomial with two quadratic parts and one linear.
+*/
+
+struct stage {
+  double wander;
+  double length;
+};
+
+#define NUM_STAGES 3
+
+static struct stage stages[NUM_STAGES];
+
+/* Enabled/disabled smoothing */
+static int enabled;
+
+/* Enabled/disabled mode where only leap seconds are smoothed out and normal
+   offset/frequency changes are ignored */
+static int leap_only_mode;
+
+/* Maximum skew/max_wander ratio to start updating offset and frequency */
+#define UNLOCK_SKEW_WANDER_RATIO 10000
+
+static int locked;
+
+/* Maximum wander and frequency offset */
+static double max_wander;
+static double max_freq;
+
+/* Frequency offset, time offset and the time of the last smoothing update */
+static double smooth_freq;
+static double smooth_offset;
+static struct timespec last_update;
+
+
+static void
+get_smoothing(struct timespec *now, double *poffset, double *pfreq,
+              double *pwander)
+{
+  double elapsed, length, offset, freq, wander;
+  int i;
+
+  elapsed = UTI_DiffTimespecsToDouble(now, &last_update);
+
+  offset = smooth_offset;
+  freq = smooth_freq;
+  wander = 0.0;
+
+  for (i = 0; i < NUM_STAGES; i++) {
+    if (elapsed <= 0.0)
+      break;
+
+    length = stages[i].length;
+    if (length >= elapsed)
+      length = elapsed;
+
+    wander = stages[i].wander;
+    offset -= length * (2.0 * freq + wander * length) / 2.0;
+    freq += wander * length;
+    elapsed -= length;
+  }
+
+  if (elapsed > 0.0) {
+    wander = 0.0;
+    offset -= elapsed * freq;
+  }
+
+  *poffset = offset;
+  *pfreq = freq;
+  if (pwander)
+    *pwander = wander;
+}
+
+static void
+update_stages(void)
+{
+  double s1, s2, s, l1, l2, l3, lc, f, f2, l1t[2], l3t[2], err[2];
+  int i, dir;
+
+  /* Prepare the three stages so that the integral of the frequency offset
+     is equal to the offset that should be smoothed out */
+
+  s1 = smooth_offset / max_wander;
+  s2 = SQUARE(smooth_freq) / (2.0 * SQUARE(max_wander));
+  
+  /* Calculate the lengths of the 1st and 3rd stage assuming there is no
+     frequency limit.  The direction of the 1st stage is selected so that
+     the lengths will not be negative.  With extremely small offsets both
+     directions may give a negative length due to numerical errors, so select
+     the one which gives a smaller error. */
+
+  for (i = 0, dir = -1; i <= 1; i++, dir += 2) {
+    err[i] = 0.0;
+    s = dir * s1 + s2;
+
+    if (s < 0.0) {
+      err[i] += -s;
+      s = 0.0;
+    }
+
+    l3t[i] = sqrt(s);
+    l1t[i] = l3t[i] - dir * smooth_freq / max_wander;
+
+    if (l1t[i] < 0.0) {
+      err[i] += l1t[i] * l1t[i];
+      l1t[i] = 0.0;
+    }
+  }
+
+  if (err[0] < err[1]) {
+    l1 = l1t[0];
+    l3 = l3t[0];
+    dir = -1;
+  } else {
+    l1 = l1t[1];
+    l3 = l3t[1];
+    dir = 1;
+  }
+
+  l2 = 0.0;
+
+  /* If the limit was reached, shorten 1st+3rd stages and set a 2nd stage */
+  f = dir * smooth_freq + l1 * max_wander - max_freq;
+  if (f > 0.0) {
+    lc = f / max_wander;
+
+    /* No 1st stage if the frequency is already above the maximum */
+    if (lc > l1) {
+      lc = l1;
+      f2 = dir * smooth_freq;
+    } else {
+      f2 = max_freq;
+    }
+
+    l2 = lc * (2.0 + f / f2);
+    l1 -= lc;
+    l3 -= lc;
+  }
+
+  stages[0].wander = dir * max_wander;
+  stages[0].length = l1;
+  stages[1].wander = 0.0;
+  stages[1].length = l2;
+  stages[2].wander = -dir * max_wander;
+  stages[2].length = l3;
+
+  for (i = 0; i < NUM_STAGES; i++) {
+    DEBUG_LOG("Smooth stage %d wander %e length %f",
+              i + 1, stages[i].wander, stages[i].length);
+  }
+}
+
+static void
+update_smoothing(struct timespec *now, double offset, double freq)
+{
+  /* Don't accept offset/frequency until the clock has stabilized */
+  if (locked) {
+    if (REF_GetSkew() / max_wander < UNLOCK_SKEW_WANDER_RATIO || leap_only_mode)
+      SMT_Activate(now);
+    return;
+  }
+
+  get_smoothing(now, &smooth_offset, &smooth_freq, NULL);
+  smooth_offset += offset;
+  smooth_freq = (smooth_freq - freq) / (1.0 - freq);
+  last_update = *now;
+
+  update_stages();
+
+  DEBUG_LOG("Smooth offset %e freq %e", smooth_offset, smooth_freq);
+}
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  double delta;
+
+  if (change_type == LCL_ChangeAdjust) {
+    if (leap_only_mode)
+      update_smoothing(cooked, 0.0, 0.0);
+    else
+      update_smoothing(cooked, doffset, dfreq);
+  }
+
+  if (!UTI_IsZeroTimespec(&last_update))
+    UTI_AdjustTimespec(&last_update, cooked, &last_update, &delta, dfreq, doffset);
+}
+
+void SMT_Initialise(void)
+{
+  CNF_GetSmooth(&max_freq, &max_wander, &leap_only_mode);
+  if (max_freq <= 0.0 || max_wander <= 0.0) {
+      enabled = 0;
+      return;
+  }
+
+  enabled = 1;
+  locked = 1;
+
+  /* Convert from ppm */
+  max_freq *= 1e-6;
+  max_wander *= 1e-6;
+
+  UTI_ZeroTimespec(&last_update);
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
+}
+
+void SMT_Finalise(void)
+{
+  if (!enabled)
+    return;
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+}
+
+int SMT_IsEnabled(void)
+{
+  return enabled;
+}
+
+double
+SMT_GetOffset(struct timespec *now)
+{
+  double offset, freq;
+
+  if (!enabled)
+    return 0.0;
+  
+  get_smoothing(now, &offset, &freq, NULL);
+
+  return offset;
+}
+
+void
+SMT_Activate(struct timespec *now)
+{
+  if (!enabled || !locked)
+    return;
+
+  LOG(LOGS_INFO, "Activated %s%s", "time smoothing", leap_only_mode ?
+      " (leap seconds only)" : "");
+  locked = 0;
+  last_update = *now;
+}
+
+void
+SMT_Reset(struct timespec *now)
+{
+  int i;
+
+  if (!enabled)
+    return;
+
+  smooth_offset = 0.0;
+  smooth_freq = 0.0;
+  last_update = *now;
+
+  for (i = 0; i < NUM_STAGES; i++)
+    stages[i].wander = stages[i].length = 0.0;
+
+  LOG(LOGS_INFO, "Reset %s", "time smoothing");
+}
+
+void
+SMT_Leap(struct timespec *now, int leap)
+{
+  /* When the leap-only mode is disabled, the leap second will be accumulated
+     in handle_slew() as a normal offset */
+  if (!enabled || !leap_only_mode)
+    return;
+
+  update_smoothing(now, leap, 0.0);
+}
+
+int
+SMT_GetSmoothingReport(RPT_SmoothingReport *report, struct timespec *now)
+{
+  double length, elapsed;
+  int i;
+
+  if (!enabled)
+    return 0;
+
+  report->active = !locked;
+  report->leap_only = leap_only_mode;
+
+  get_smoothing(now, &report->offset, &report->freq_ppm, &report->wander_ppm);
+
+  /* Convert to ppm and negate (positive values mean faster/speeding up) */
+  report->freq_ppm *= -1.0e6;
+  report->wander_ppm *= -1.0e6;
+
+  elapsed = UTI_DiffTimespecsToDouble(now, &last_update);
+  if (!locked && elapsed >= 0.0) {
+    for (i = 0, length = 0.0; i < NUM_STAGES; i++)
+      length += stages[i].length;
+    report->last_update_ago = elapsed;
+    report->remaining_time = elapsed < length ? length - elapsed : 0.0;
+  } else {
+    report->last_update_ago = 0.0;
+    report->remaining_time = 0.0;
+  }
+
+  return 1;
+}
diff --git a/smooth.h b/smooth.h
new file mode 100644
index 0000000..4e84504
--- /dev/null
+++ b/smooth.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This module implements time smoothing.
+  */
+
+#ifndef GOT_SMOOTH_H
+#define GOT_SMOOTH_H
+
+#include "reports.h"
+
+extern void SMT_Initialise(void);
+
+extern void SMT_Finalise(void);
+
+extern int SMT_IsEnabled(void);
+
+extern double SMT_GetOffset(struct timespec *now);
+
+extern void SMT_Activate(struct timespec *now);
+
+extern void SMT_Reset(struct timespec *now);
+
+extern void SMT_Leap(struct timespec *now, int leap);
+
+extern int SMT_GetSmoothingReport(RPT_SmoothingReport *report, struct timespec *now);
+
+#endif
diff --git a/socket.c b/socket.c
new file mode 100644
index 0000000..aa060a8
--- /dev/null
+++ b/socket.c
@@ -0,0 +1,1648 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Timo Teras  2009
+ * Copyright (C) Miroslav Lichvar  2009, 2013-2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file implements socket operations.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include <linux/errqueue.h>
+#include <linux/net_tstamp.h>
+#endif
+
+#include "socket.h"
+#include "array.h"
+#include "logging.h"
+#include "privops.h"
+#include "ptp.h"
+#include "util.h"
+
+#define INVALID_SOCK_FD (-4)
+#define CMSG_BUF_SIZE 256
+
+union sockaddr_all {
+  struct sockaddr_in in4;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 in6;
+#endif
+  struct sockaddr_un un;
+  struct sockaddr sa;
+};
+
+struct Message {
+  union sockaddr_all name;
+  struct iovec iov;
+  /* Buffer of sufficient length for all expected messages */
+  struct {
+    /* Extra space for Ethernet, IPv4/IPv6, and UDP headers in
+       timestamped messages received from the Linux error queue */
+    uint8_t l234_headers[64];
+    union {
+      NTP_Packet ntp_msg;
+      PTP_NtpMessage ptp_msg;
+      CMD_Request cmd_request;
+      CMD_Reply cmd_reply;
+    } msg;
+  } msg_buf;
+  /* Aligned buffer for control messages */
+  struct cmsghdr cmsg_buf[CMSG_BUF_SIZE / sizeof (struct cmsghdr)];
+};
+
+#ifdef HAVE_RECVMMSG
+#define MAX_RECV_MESSAGES 16
+#define MessageHeader mmsghdr
+#else
+/* Compatible with mmsghdr */
+struct MessageHeader {
+  struct msghdr msg_hdr;
+  unsigned int msg_len;
+};
+
+#define MAX_RECV_MESSAGES 1
+#endif
+
+static int initialised;
+
+/* Flags indicating in which IP families sockets can be requested */
+static int ip4_enabled;
+static int ip6_enabled;
+
+/* Flags supported by socket() */
+static int supported_socket_flags;
+
+/* Arrays of Message, MessageHeader, and SCK_Message */
+static ARR_Instance recv_messages;
+static ARR_Instance recv_headers;
+static ARR_Instance recv_sck_messages;
+
+static unsigned int received_messages;
+
+static int (*priv_bind_function)(int sock_fd, struct sockaddr *address,
+                                 socklen_t address_len);
+
+/* ================================================== */
+
+static void
+prepare_buffers(unsigned int n)
+{
+  struct MessageHeader *hdr;
+  struct Message *msg;
+  unsigned int i;
+
+  for (i = 0; i < n; i++) {
+    msg = ARR_GetElement(recv_messages, i);
+    hdr = ARR_GetElement(recv_headers, i);
+
+    msg->iov.iov_base = &msg->msg_buf;
+    msg->iov.iov_len = sizeof (msg->msg_buf);
+    hdr->msg_hdr.msg_name = &msg->name;
+    hdr->msg_hdr.msg_namelen = sizeof (msg->name);
+    hdr->msg_hdr.msg_iov = &msg->iov;
+    hdr->msg_hdr.msg_iovlen = 1;
+    hdr->msg_hdr.msg_control = msg->cmsg_buf;
+    hdr->msg_hdr.msg_controllen = sizeof (msg->cmsg_buf);
+    hdr->msg_hdr.msg_flags = 0;
+    hdr->msg_len = 0;
+  }
+}
+
+/* ================================================== */
+
+static const char *
+domain_to_string(int domain)
+{
+  switch (domain) {
+    case AF_INET:
+      return "IPv4";
+#ifdef AF_INET6
+    case AF_INET6:
+      return "IPv6";
+#endif
+    case AF_UNIX:
+      return "Unix";
+    case AF_UNSPEC:
+      return "UNSPEC";
+    default:
+      return "?";
+  }
+}
+
+/* ================================================== */
+
+#if defined(SOCK_CLOEXEC) || defined(SOCK_NONBLOCK)
+static int
+check_socket_flag(int sock_flag, int fd_flag, int fs_flag)
+{
+  int sock_fd, fd_flags, fs_flags;
+
+  sock_fd = socket(AF_INET, SOCK_DGRAM | sock_flag, 0);
+  if (sock_fd < 0)
+    return 0;
+
+  fd_flags = fcntl(sock_fd, F_GETFD);
+  fs_flags = fcntl(sock_fd, F_GETFL);
+
+  close(sock_fd);
+
+  if (fd_flags == -1 || (fd_flags & fd_flag) != fd_flag ||
+      fs_flags == -1 || (fs_flags & fs_flag) != fs_flag)
+    return 0;
+
+  return 1;
+}
+#endif
+
+/* ================================================== */
+
+static int
+set_socket_nonblock(int sock_fd)
+{
+  if (fcntl(sock_fd, F_SETFL, O_NONBLOCK) < 0) {
+    DEBUG_LOG("Could not set O_NONBLOCK : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+get_open_flags(int flags)
+{
+  int r = supported_socket_flags;
+
+#ifdef SOCK_NONBLOCK
+  if (flags & SCK_FLAG_BLOCK)
+    r &= ~SOCK_NONBLOCK;
+#endif
+
+  return r;
+}
+
+/* ================================================== */
+
+static int
+set_socket_flags(int sock_fd, int flags)
+{
+  /* Close the socket automatically on exec */
+  if (
+#ifdef SOCK_CLOEXEC
+      (supported_socket_flags & SOCK_CLOEXEC) == 0 &&
+#endif
+      !UTI_FdSetCloexec(sock_fd))
+    return 0;
+
+  /* Enable non-blocking mode */
+  if ((flags & SCK_FLAG_BLOCK) == 0 &&
+#ifdef SOCK_NONBLOCK
+      (supported_socket_flags & SOCK_NONBLOCK) == 0 &&
+#endif
+      !set_socket_nonblock(sock_fd))
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_socket(int domain, int type, int flags)
+{
+  int sock_fd;
+
+  sock_fd = socket(domain, type | get_open_flags(flags), 0);
+
+  if (sock_fd < 0) {
+    DEBUG_LOG("Could not open %s socket : %s",
+              domain_to_string(domain), strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!set_socket_flags(sock_fd, flags)) {
+    close(sock_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+open_socket_pair(int domain, int type, int flags, int *other_fd)
+{
+  int sock_fds[2];
+
+  if (socketpair(domain, type | get_open_flags(flags), 0, sock_fds) < 0) {
+    DEBUG_LOG("Could not open %s socket : %s",
+              domain_to_string(domain), strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!set_socket_flags(sock_fds[0], flags) || !set_socket_flags(sock_fds[1], flags)) {
+    close(sock_fds[0]);
+    close(sock_fds[1]);
+    return INVALID_SOCK_FD;
+  }
+
+  *other_fd = sock_fds[1];
+
+  return sock_fds[0];
+}
+
+/* ================================================== */
+
+static int
+set_socket_options(int sock_fd, int flags)
+{
+  /* Make the socket capable of sending broadcast packets if requested */
+  if (flags & SCK_FLAG_BROADCAST && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_BROADCAST, 1))
+    ;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+set_ip_options(int sock_fd, int family, int flags)
+{
+#if defined(FEAT_IPV6) && defined(IPV6_V6ONLY)
+  /* Receive only IPv6 packets on an IPv6 socket */
+  if (family == IPADDR_INET6 && !SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_V6ONLY, 1))
+    return 0;
+#endif
+
+  /* Provide destination address of received packets if requested */
+  if (flags & SCK_FLAG_RX_DEST_ADDR) {
+    if (family == IPADDR_INET4) {
+#ifdef HAVE_IN_PKTINFO
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_PKTINFO, 1))
+        ;
+#elif defined(IP_RECVDSTADDR)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_RECVDSTADDR, 1))
+        ;
+#endif
+    }
+#ifdef FEAT_IPV6
+    else if (family == IPADDR_INET6) {
+#ifdef HAVE_IN6_PKTINFO
+#ifdef IPV6_RECVPKTINFO
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, 1))
+        ;
+#else
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_PKTINFO, 1))
+        ;
+#endif
+#endif
+    }
+#endif
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+is_any_address(IPAddr *addr)
+{
+  IPAddr any_addr;
+
+  SCK_GetAnyLocalIPAddress(addr->family, &any_addr);
+
+  return UTI_CompareIPs(&any_addr, addr, NULL) == 0;
+}
+
+/* ================================================== */
+
+static int
+bind_device(int sock_fd, const char *iface)
+{
+#ifdef SO_BINDTODEVICE
+  if (setsockopt(sock_fd, SOL_SOCKET, SO_BINDTODEVICE, iface, strlen(iface) + 1) < 0) {
+    DEBUG_LOG("Could not bind socket to %s : %s", iface, strerror(errno));
+    return 0;
+  }
+  return 1;
+#else
+  DEBUG_LOG("Could not bind socket to %s : %s", iface, "Not supported");
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+bind_ip_address(int sock_fd, IPSockAddr *addr, int flags)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+  int s;
+
+  /* Make the socket capable of re-using an old address if binding to a specific port */
+  if (addr->port > 0 && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_REUSEADDR, 1))
+    ;
+
+#if defined(LINUX) && defined(SO_REUSEPORT)
+  /* Allow multiple instances to bind to the same port in order to enable load
+     balancing.  Don't enable this option on non-Linux systems as it has
+     a slightly different meaning there (with some important implications). */
+  if (addr->port > 0 && !SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_REUSEPORT, 1))
+    ;
+#endif
+
+#ifdef IP_FREEBIND
+  /* Allow binding to an address that doesn't exist yet */
+  if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_FREEBIND, 1))
+    ;
+#endif
+
+  saddr_len = SCK_IPSockAddrToSockaddr(addr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (saddr_len == 0)
+    return 0;
+
+  if (flags & SCK_FLAG_PRIV_BIND && priv_bind_function)
+    s = priv_bind_function(sock_fd, &saddr.sa, saddr_len);
+  else
+    s = bind(sock_fd, &saddr.sa, saddr_len);
+
+  if (s < 0) {
+    DEBUG_LOG("Could not bind socket to %s : %s",
+              UTI_IPSockAddrToString(addr), strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+connect_ip_address(int sock_fd, IPSockAddr *addr)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+
+  saddr_len = SCK_IPSockAddrToSockaddr(addr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (saddr_len == 0)
+    return 0;
+
+  if (connect(sock_fd, &saddr.sa, saddr_len) < 0 && errno != EINPROGRESS) {
+    DEBUG_LOG("Could not connect socket to %s : %s",
+              UTI_IPSockAddrToString(addr), strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_ip_socket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface,
+               int type, int flags)
+{
+  int domain, family, sock_fd;
+
+  if (local_addr)
+    family = local_addr->ip_addr.family;
+  else if (remote_addr)
+    family = remote_addr->ip_addr.family;
+  else
+    family = IPADDR_INET4;
+
+  switch (family) {
+    case IPADDR_INET4:
+      if (!ip4_enabled)
+        return INVALID_SOCK_FD;
+      domain = AF_INET;
+      break;
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      if (!ip6_enabled)
+        return INVALID_SOCK_FD;
+      domain = AF_INET6;
+      break;
+#endif
+    default:
+      DEBUG_LOG("Unspecified family");
+      return INVALID_SOCK_FD;
+  }
+
+  sock_fd = open_socket(domain, type, flags);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!set_socket_options(sock_fd, flags))
+    goto error;
+
+  if (!set_ip_options(sock_fd, family, flags))
+    goto error;
+
+  if (iface && !bind_device(sock_fd, iface))
+    goto error;
+
+  /* Bind the socket if a non-any local address/port was specified */
+  if (local_addr && local_addr->ip_addr.family != IPADDR_UNSPEC &&
+      (local_addr->port != 0 || !is_any_address(&local_addr->ip_addr)) &&
+      !bind_ip_address(sock_fd, local_addr, flags))
+    goto error;
+
+  /* Connect the socket if a remote address was specified */
+  if (remote_addr && remote_addr->ip_addr.family != IPADDR_UNSPEC &&
+      !connect_ip_address(sock_fd, remote_addr))
+    goto error;
+
+  if (remote_addr || local_addr)
+    DEBUG_LOG("Opened %s%s socket fd=%d%s%s%s%s",
+              type == SOCK_DGRAM ? "UDP" : type == SOCK_STREAM ? "TCP" : "?",
+              family == IPADDR_INET4 ? "v4" : "v6",
+              sock_fd,
+              remote_addr ? " remote=" : "",
+              remote_addr ? UTI_IPSockAddrToString(remote_addr) : "",
+              local_addr ? " local=" : "",
+              local_addr ? UTI_IPSockAddrToString(local_addr) : "");
+
+  return sock_fd;
+
+error:
+  SCK_CloseSocket(sock_fd);
+  return INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+bind_unix_address(int sock_fd, const char *addr, int flags)
+{
+  union sockaddr_all saddr;
+
+  memset(&saddr, 0, sizeof (saddr));
+
+  if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s", addr) >=
+      sizeof (saddr.un.sun_path)) {
+    DEBUG_LOG("Unix socket path %s too long", addr);
+    return 0;
+  }
+  saddr.un.sun_family = AF_UNIX;
+
+  if (unlink(addr) < 0)
+    DEBUG_LOG("Could not remove %s : %s", addr, strerror(errno));
+
+  /* PRV_BindSocket() doesn't support Unix sockets yet */
+  if (bind(sock_fd, &saddr.sa, sizeof (saddr.un)) < 0) {
+    DEBUG_LOG("Could not bind Unix socket to %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  /* Allow access to everyone with access to the directory if requested */
+  if (flags & SCK_FLAG_ALL_PERMISSIONS && chmod(addr, 0666) < 0) {
+    DEBUG_LOG("Could not change permissions of %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+connect_unix_address(int sock_fd, const char *addr)
+{
+  union sockaddr_all saddr;
+
+  memset(&saddr, 0, sizeof (saddr));
+
+  if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s", addr) >=
+      sizeof (saddr.un.sun_path)) {
+    DEBUG_LOG("Unix socket path %s too long", addr);
+    return 0;
+  }
+  saddr.un.sun_family = AF_UNIX;
+
+  if (connect(sock_fd, &saddr.sa, sizeof (saddr.un)) < 0) {
+    DEBUG_LOG("Could not connect Unix socket to %s : %s", addr, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+open_unix_socket(const char *remote_addr, const char *local_addr, int type, int flags)
+{
+  int sock_fd;
+
+  sock_fd = open_socket(AF_UNIX, type, flags);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  if (!set_socket_options(sock_fd, flags))
+    goto error;
+
+  /* Bind the socket if a local address was specified */
+  if (local_addr && !bind_unix_address(sock_fd, local_addr, flags))
+    goto error;
+
+  /* Connect the socket if a remote address was specified */
+  if (remote_addr && !connect_unix_address(sock_fd, remote_addr))
+    goto error;
+
+  DEBUG_LOG("Opened Unix socket fd=%d%s%s%s%s",
+            sock_fd,
+            remote_addr ? " remote=" : "", remote_addr ? remote_addr : "",
+            local_addr ? " local=" : "", local_addr ? local_addr : "");
+
+  return sock_fd;
+
+error:
+  SCK_RemoveSocket(sock_fd);
+  SCK_CloseSocket(sock_fd);
+  return INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+open_unix_socket_pair(int type, int flags, int *other_fd)
+{
+  int sock_fd;
+
+  sock_fd = open_socket_pair(AF_UNIX, type, flags, other_fd);
+  if (sock_fd < 0)
+    return INVALID_SOCK_FD;
+
+  DEBUG_LOG("Opened Unix socket pair fd1=%d fd2=%d", sock_fd, *other_fd);
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+static int
+get_recv_flags(int flags)
+{
+  int recv_flags = 0;
+
+  if (flags & SCK_FLAG_MSG_ERRQUEUE) {
+#ifdef MSG_ERRQUEUE
+    recv_flags |= MSG_ERRQUEUE;
+#else
+    assert(0);
+#endif
+  }
+
+  return recv_flags;
+}
+
+/* ================================================== */
+
+static void
+handle_recv_error(int sock_fd, int flags)
+{
+#ifdef MSG_ERRQUEUE
+  /* If reading from the error queue failed, the select() exception should
+     be for a socket error.  Clear the error to avoid a busy loop. */
+  if (flags & SCK_FLAG_MSG_ERRQUEUE) {
+    int error = 0;
+
+    if (SCK_GetIntOption(sock_fd, SOL_SOCKET, SO_ERROR, &error))
+      errno = error;
+  }
+#endif
+
+  DEBUG_LOG("Could not receive message fd=%d : %s", sock_fd, strerror(errno));
+}
+
+/* ================================================== */
+
+static void
+log_message(int sock_fd, int direction, SCK_Message *message, const char *prefix,
+            const char *error)
+{
+  const char *local_addr, *remote_addr;
+  char if_index[20], tss[10], tsif[20], tslen[20];
+
+  if (DEBUG <= 0 || log_min_severity > LOGS_DEBUG)
+    return;
+
+  remote_addr = NULL;
+  local_addr = NULL;
+  if_index[0] = '\0';
+  tss[0] = '\0';
+  tsif[0] = '\0';
+  tslen[0] = '\0';
+
+  switch (message->addr_type) {
+    case SCK_ADDR_IP:
+      if (message->remote_addr.ip.ip_addr.family != IPADDR_UNSPEC)
+        remote_addr = UTI_IPSockAddrToString(&message->remote_addr.ip);
+      if (message->local_addr.ip.family != IPADDR_UNSPEC)
+        local_addr = UTI_IPToString(&message->local_addr.ip);
+      break;
+    case SCK_ADDR_UNIX:
+      remote_addr = message->remote_addr.path;
+      break;
+    default:
+      break;
+  }
+
+  if (message->if_index != INVALID_IF_INDEX)
+    snprintf(if_index, sizeof (if_index), " if=%d", message->if_index);
+
+  if (direction > 0) {
+    if (!UTI_IsZeroTimespec(&message->timestamp.kernel) ||
+        !UTI_IsZeroTimespec(&message->timestamp.hw))
+      snprintf(tss, sizeof (tss), " tss=%s%s",
+               !UTI_IsZeroTimespec(&message->timestamp.kernel) ? "K" : "",
+               !UTI_IsZeroTimespec(&message->timestamp.hw) ? "H" : "");
+
+    if (message->timestamp.if_index != INVALID_IF_INDEX)
+      snprintf(tsif, sizeof (tsif), " tsif=%d", message->timestamp.if_index);
+
+    if (message->timestamp.l2_length != 0)
+      snprintf(tslen, sizeof (tslen), " tslen=%d", message->timestamp.l2_length);
+  }
+
+  DEBUG_LOG("%s message%s%s%s%s fd=%d len=%d%s%s%s%s%s%s",
+            prefix,
+            remote_addr ? (direction > 0 ? " from " : " to ") : "",
+            remote_addr ? remote_addr : "",
+            local_addr ? (direction > 0 ? " to " : " from ") : "",
+            local_addr ? local_addr : "",
+            sock_fd, message->length, if_index,
+            tss, tsif, tslen,
+            error ? " : " : "", error ? error : "");
+}
+
+/* ================================================== */
+
+static void
+init_message_addresses(SCK_Message *message, SCK_AddressType addr_type)
+{
+  message->addr_type = addr_type;
+
+  switch (addr_type) {
+    case SCK_ADDR_UNSPEC:
+      break;
+    case SCK_ADDR_IP:
+      message->remote_addr.ip.ip_addr.family = IPADDR_UNSPEC;
+      message->remote_addr.ip.port = 0;
+      message->local_addr.ip.family = IPADDR_UNSPEC;
+      break;
+    case SCK_ADDR_UNIX:
+      message->remote_addr.path = NULL;
+      break;
+    default:
+      assert(0);
+  }
+}
+
+/* ================================================== */
+
+static void
+init_message_nonaddress(SCK_Message *message)
+{
+  message->data = NULL;
+  message->length = 0;
+  message->if_index = INVALID_IF_INDEX;
+
+  UTI_ZeroTimespec(&message->timestamp.kernel);
+  UTI_ZeroTimespec(&message->timestamp.hw);
+  message->timestamp.if_index = INVALID_IF_INDEX;
+  message->timestamp.l2_length = 0;
+  message->timestamp.tx_flags = 0;
+
+  message->descriptor = INVALID_SOCK_FD;
+}
+
+/* ================================================== */
+
+static int
+match_cmsg(struct cmsghdr *cmsg, int level, int type, size_t length)
+{
+  if (cmsg->cmsg_type == type && cmsg->cmsg_level == level &&
+      (length == 0 || cmsg->cmsg_len == CMSG_LEN(length)))
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+process_header(struct msghdr *msg, int msg_length, int sock_fd, int flags,
+               SCK_Message *message)
+{
+  struct cmsghdr *cmsg;
+  int r = 1;
+
+  if (msg->msg_namelen <= sizeof (union sockaddr_all) &&
+      msg->msg_namelen > sizeof (((struct sockaddr *)msg->msg_name)->sa_family)) {
+    switch (((struct sockaddr *)msg->msg_name)->sa_family) {
+      case AF_INET:
+#ifdef FEAT_IPV6
+      case AF_INET6:
+#endif
+        init_message_addresses(message, SCK_ADDR_IP);
+        SCK_SockaddrToIPSockAddr(msg->msg_name, msg->msg_namelen, &message->remote_addr.ip);
+        break;
+      case AF_UNIX:
+        init_message_addresses(message, SCK_ADDR_UNIX);
+        message->remote_addr.path = ((struct sockaddr_un *)msg->msg_name)->sun_path;
+        break;
+      default:
+        init_message_addresses(message, SCK_ADDR_UNSPEC);
+        DEBUG_LOG("Unexpected address");
+        r = 0;
+        break;
+    }
+  } else {
+    init_message_addresses(message, SCK_ADDR_UNSPEC);
+
+    if (msg->msg_namelen > sizeof (union sockaddr_all)) {
+      DEBUG_LOG("Truncated source address");
+      r = 0;
+    }
+  }
+
+  init_message_nonaddress(message);
+
+  if (msg->msg_iovlen == 1) {
+    message->data = msg->msg_iov[0].iov_base;
+    message->length = msg_length;
+  } else {
+    DEBUG_LOG("Unexpected iovlen");
+    r = 0;
+  }
+
+  if (msg->msg_flags & MSG_TRUNC) {
+    log_message(sock_fd, 1, message, "Truncated", NULL);
+    r = 0;
+  }
+
+  if (msg->msg_flags & MSG_CTRUNC) {
+    log_message(sock_fd, 1, message, "Truncated cmsg in", NULL);
+    r = 0;
+  }
+
+  for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+    if (0) {
+    }
+#ifdef HAVE_IN_PKTINFO
+    else if (match_cmsg(cmsg, IPPROTO_IP, IP_PKTINFO, sizeof (struct in_pktinfo))) {
+      struct in_pktinfo ipi;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&ipi, CMSG_DATA(cmsg), sizeof (ipi));
+      message->local_addr.ip.addr.in4 = ntohl(ipi.ipi_addr.s_addr);
+      message->local_addr.ip.family = IPADDR_INET4;
+      message->if_index = ipi.ipi_ifindex;
+    }
+#elif defined(IP_RECVDSTADDR)
+    else if (match_cmsg(cmsg, IPPROTO_IP, IP_RECVDSTADDR, sizeof (struct in_addr))) {
+      struct in_addr addr;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&addr, CMSG_DATA(cmsg), sizeof (addr));
+      message->local_addr.ip.addr.in4 = ntohl(addr.s_addr);
+      message->local_addr.ip.family = IPADDR_INET4;
+    }
+#endif
+#ifdef HAVE_IN6_PKTINFO
+    else if (match_cmsg(cmsg, IPPROTO_IPV6, IPV6_PKTINFO, sizeof (struct in6_pktinfo))) {
+      struct in6_pktinfo ipi;
+
+      if (message->addr_type != SCK_ADDR_IP)
+        init_message_addresses(message, SCK_ADDR_IP);
+
+      memcpy(&ipi, CMSG_DATA(cmsg), sizeof (ipi));
+      memcpy(&message->local_addr.ip.addr.in6, &ipi.ipi6_addr.s6_addr,
+             sizeof (message->local_addr.ip.addr.in6));
+      message->local_addr.ip.family = IPADDR_INET6;
+      message->if_index = ipi.ipi6_ifindex;
+    }
+#endif
+#ifdef SCM_TIMESTAMP
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMP, sizeof (struct timeval))) {
+      struct timeval tv;
+
+      memcpy(&tv, CMSG_DATA(cmsg), sizeof (tv));
+      UTI_TimevalToTimespec(&tv, &message->timestamp.kernel);
+    }
+#endif
+#ifdef SCM_TIMESTAMPNS
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPNS, sizeof (message->timestamp.kernel))) {
+      memcpy(&message->timestamp.kernel, CMSG_DATA(cmsg), sizeof (message->timestamp.kernel));
+    }
+#endif
+#ifdef SCM_REALTIME
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_REALTIME, sizeof (message->timestamp.kernel))) {
+      memcpy(&message->timestamp.kernel, CMSG_DATA(cmsg), sizeof (message->timestamp.kernel));
+    }
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+#ifdef HAVE_LINUX_TIMESTAMPING_OPT_PKTINFO
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPING_PKTINFO,
+                        sizeof (struct scm_ts_pktinfo))) {
+      struct scm_ts_pktinfo ts_pktinfo;
+
+      memcpy(&ts_pktinfo, CMSG_DATA(cmsg), sizeof (ts_pktinfo));
+      message->timestamp.if_index = ts_pktinfo.if_index;
+      message->timestamp.l2_length = ts_pktinfo.pkt_length;
+    }
+#endif
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_TIMESTAMPING,
+                        sizeof (struct scm_timestamping))) {
+      struct scm_timestamping ts3;
+
+      memcpy(&ts3, CMSG_DATA(cmsg), sizeof (ts3));
+      message->timestamp.kernel = ts3.ts[0];
+      message->timestamp.hw = ts3.ts[2];
+    }
+    else if ((match_cmsg(cmsg, SOL_IP, IP_RECVERR, 0) ||
+              match_cmsg(cmsg, SOL_IPV6, IPV6_RECVERR, 0)) &&
+             cmsg->cmsg_len >= CMSG_LEN(sizeof (struct sock_extended_err))) {
+      struct sock_extended_err err;
+
+      memcpy(&err, CMSG_DATA(cmsg), sizeof (err));
+
+      if (err.ee_errno != ENOMSG || err.ee_info != SCM_TSTAMP_SND ||
+          err.ee_origin != SO_EE_ORIGIN_TIMESTAMPING) {
+        log_message(sock_fd, 1, message, "Unexpected extended error in", NULL);
+        r = 0;
+      }
+    }
+#endif
+    else if (match_cmsg(cmsg, SOL_SOCKET, SCM_RIGHTS, 0)) {
+      if (!(flags & SCK_FLAG_MSG_DESCRIPTOR) || cmsg->cmsg_len != CMSG_LEN(sizeof (int))) {
+        int i, fd;
+
+        DEBUG_LOG("Unexpected SCM_RIGHTS");
+        for (i = 0; CMSG_LEN((i + 1) * sizeof (int)) <= cmsg->cmsg_len; i++) {
+          memcpy(&fd, (char *)CMSG_DATA(cmsg) + i * sizeof (int), sizeof (fd));
+          close(fd);
+        }
+        r = 0;
+      } else {
+        memcpy(&message->descriptor, CMSG_DATA(cmsg), sizeof (message->descriptor));
+      }
+    }
+    else {
+      DEBUG_LOG("Unexpected control message level=%d type=%d len=%d",
+                cmsg->cmsg_level, cmsg->cmsg_type, (int)cmsg->cmsg_len);
+    }
+  }
+
+  if (!r && message->descriptor != INVALID_SOCK_FD)
+    close(message->descriptor);
+
+  return r;
+}
+
+/* ================================================== */
+
+static SCK_Message *
+receive_messages(int sock_fd, int flags, int max_messages, int *num_messages)
+{
+  struct MessageHeader *hdr;
+  SCK_Message *messages;
+  unsigned int i, n, n_ok;
+  int ret, recv_flags = 0;
+
+  assert(initialised);
+
+  *num_messages = 0;
+
+  if (max_messages < 1)
+    return NULL;
+
+  /* Prepare used buffers for new messages */
+  prepare_buffers(received_messages);
+  received_messages = 0;
+
+  messages = ARR_GetElements(recv_sck_messages);
+
+  hdr = ARR_GetElements(recv_headers);
+  n = ARR_GetSize(recv_headers);
+  n = MIN(n, max_messages);
+
+  if (n < 1 || n > MAX_RECV_MESSAGES ||
+      n > ARR_GetSize(recv_messages) || n > ARR_GetSize(recv_sck_messages))
+    assert(0);
+
+  recv_flags = get_recv_flags(flags);
+
+#ifdef HAVE_RECVMMSG
+  ret = recvmmsg(sock_fd, hdr, n, recv_flags, NULL);
+  if (ret >= 0)
+    n = ret;
+#else
+  n = 1;
+  ret = recvmsg(sock_fd, &hdr[0].msg_hdr, recv_flags);
+  if (ret >= 0)
+    hdr[0].msg_len = ret;
+#endif
+
+  if (ret < 0) {
+    handle_recv_error(sock_fd, flags);
+    return NULL;
+  }
+
+  received_messages = n;
+
+  for (i = n_ok = 0; i < n; i++) {
+    hdr = ARR_GetElement(recv_headers, i);
+    if (!process_header(&hdr->msg_hdr, hdr->msg_len, sock_fd, flags, &messages[n_ok]))
+      continue;
+
+    log_message(sock_fd, 1, &messages[n_ok],
+                flags & SCK_FLAG_MSG_ERRQUEUE ? "Received error" : "Received", NULL);
+
+    n_ok++;
+  }
+
+  *num_messages = n_ok;
+
+  return n_ok > 0 ? messages : NULL;
+}
+
+/* ================================================== */
+
+static void *
+add_control_message(struct msghdr *msg, int level, int type, size_t length, size_t buf_length)
+{
+  struct cmsghdr *cmsg;
+  size_t cmsg_space;
+
+  /* Avoid using CMSG_NXTHDR as the one in glibc does not support adding
+     control messages: https://sourceware.org/bugzilla/show_bug.cgi?id=13500 */
+
+  cmsg = msg->msg_control;
+  cmsg_space = CMSG_SPACE(length);
+
+  if (!cmsg || length > buf_length || msg->msg_controllen + cmsg_space > buf_length) {
+    DEBUG_LOG("Could not add control message level=%d type=%d", level, type);
+    return NULL;
+  }
+
+  cmsg = (struct cmsghdr *)((char *)cmsg + msg->msg_controllen);
+
+  memset(cmsg, 0, cmsg_space);
+
+  cmsg->cmsg_level = level;
+  cmsg->cmsg_type = type;
+  cmsg->cmsg_len = CMSG_LEN(length);
+
+  msg->msg_controllen += cmsg_space;
+
+  return CMSG_DATA(cmsg);
+}
+
+/* ================================================== */
+
+static int
+send_message(int sock_fd, SCK_Message *message, int flags)
+{
+  struct cmsghdr cmsg_buf[CMSG_BUF_SIZE / sizeof (struct cmsghdr)];
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+  struct msghdr msg;
+  struct iovec iov;
+
+  switch (message->addr_type) {
+    case SCK_ADDR_UNSPEC:
+      saddr_len = 0;
+      break;
+    case SCK_ADDR_IP:
+      saddr_len = SCK_IPSockAddrToSockaddr(&message->remote_addr.ip,
+                                           (struct sockaddr *)&saddr, sizeof (saddr));
+      break;
+    case SCK_ADDR_UNIX:
+      memset(&saddr, 0, sizeof (saddr));
+      if (snprintf(saddr.un.sun_path, sizeof (saddr.un.sun_path), "%s",
+                   message->remote_addr.path) >= sizeof (saddr.un.sun_path)) {
+        DEBUG_LOG("Unix socket path %s too long", message->remote_addr.path);
+        return 0;
+      }
+      saddr.un.sun_family = AF_UNIX;
+      saddr_len = sizeof (saddr.un);
+      break;
+    default:
+      assert(0);
+  }
+
+  if (saddr_len) {
+    msg.msg_name = &saddr.un;
+    msg.msg_namelen = saddr_len;
+  } else {
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+  }
+
+  if (message->length < 0) {
+    DEBUG_LOG("Invalid length %d", message->length);
+    return 0;
+  }
+
+  iov.iov_base = message->data;
+  iov.iov_len = message->length;
+  msg.msg_iov = &iov;
+  msg.msg_iovlen = 1;
+  msg.msg_control = cmsg_buf;
+  msg.msg_controllen = 0;
+  msg.msg_flags = 0;
+
+  if (message->addr_type == SCK_ADDR_IP) {
+    if (message->local_addr.ip.family == IPADDR_INET4) {
+#ifdef HAVE_IN_PKTINFO
+      struct in_pktinfo *ipi;
+
+      ipi = add_control_message(&msg, IPPROTO_IP, IP_PKTINFO, sizeof (*ipi),
+                                sizeof (cmsg_buf));
+      if (!ipi)
+        return 0;
+
+      ipi->ipi_spec_dst.s_addr = htonl(message->local_addr.ip.addr.in4);
+      if (message->if_index != INVALID_IF_INDEX)
+        ipi->ipi_ifindex = message->if_index;
+
+#elif defined(IP_SENDSRCADDR)
+      struct in_addr *addr;
+
+      addr = add_control_message(&msg, IPPROTO_IP, IP_SENDSRCADDR, sizeof (*addr),
+                                 sizeof (cmsg_buf));
+      if (!addr)
+        return 0;
+
+      addr->s_addr = htonl(message->local_addr.ip.addr.in4);
+#endif
+    }
+
+#ifdef HAVE_IN6_PKTINFO
+    if (message->local_addr.ip.family == IPADDR_INET6) {
+      struct in6_pktinfo *ipi;
+
+      ipi = add_control_message(&msg, IPPROTO_IPV6, IPV6_PKTINFO, sizeof (*ipi),
+                                sizeof (cmsg_buf));
+      if (!ipi)
+        return 0;
+
+      memcpy(&ipi->ipi6_addr.s6_addr, &message->local_addr.ip.addr.in6,
+             sizeof(ipi->ipi6_addr.s6_addr));
+      if (message->if_index != INVALID_IF_INDEX)
+        ipi->ipi6_ifindex = message->if_index;
+    }
+#endif
+  }
+
+#ifdef HAVE_LINUX_TIMESTAMPING
+  if (message->timestamp.tx_flags) {
+    int *ts_tx_flags;
+
+    /* Set timestamping flags for this message */
+
+    ts_tx_flags = add_control_message(&msg, SOL_SOCKET, SO_TIMESTAMPING,
+                                      sizeof (*ts_tx_flags), sizeof (cmsg_buf));
+    if (!ts_tx_flags)
+      return 0;
+
+    *ts_tx_flags = message->timestamp.tx_flags;
+  }
+#endif
+
+  if (flags & SCK_FLAG_MSG_DESCRIPTOR) {
+    int *fd;
+
+    fd = add_control_message(&msg, SOL_SOCKET, SCM_RIGHTS, sizeof (*fd), sizeof (cmsg_buf));
+    if (!fd)
+      return 0;
+
+    *fd = message->descriptor;
+  }
+
+  /* This is apparently required on some systems */
+  if (msg.msg_controllen == 0)
+    msg.msg_control = NULL;
+
+  if (sendmsg(sock_fd, &msg, 0) < 0) {
+    log_message(sock_fd, -1, message, "Could not send", strerror(errno));
+    return 0;
+  }
+
+  log_message(sock_fd, -1, message, "Sent", NULL);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SCK_Initialise(int family)
+{
+  ip4_enabled = family == IPADDR_INET4 || family == IPADDR_UNSPEC;
+#ifdef FEAT_IPV6
+  ip6_enabled = family == IPADDR_INET6 || family == IPADDR_UNSPEC;
+#else
+  ip6_enabled = 0;
+#endif
+
+  recv_messages = ARR_CreateInstance(sizeof (struct Message));
+  ARR_SetSize(recv_messages, MAX_RECV_MESSAGES);
+  recv_headers = ARR_CreateInstance(sizeof (struct MessageHeader));
+  ARR_SetSize(recv_headers, MAX_RECV_MESSAGES);
+  recv_sck_messages = ARR_CreateInstance(sizeof (SCK_Message));
+  ARR_SetSize(recv_sck_messages, MAX_RECV_MESSAGES);
+
+  received_messages = MAX_RECV_MESSAGES;
+
+  priv_bind_function = NULL;
+
+  supported_socket_flags = 0;
+#ifdef SOCK_CLOEXEC
+  if (check_socket_flag(SOCK_CLOEXEC, FD_CLOEXEC, 0))
+    supported_socket_flags |= SOCK_CLOEXEC;
+#endif
+#ifdef SOCK_NONBLOCK
+  if (check_socket_flag(SOCK_NONBLOCK, 0, O_NONBLOCK))
+    supported_socket_flags |= SOCK_NONBLOCK;
+#endif
+
+  initialised = 1;
+}
+
+/* ================================================== */
+
+void
+SCK_Finalise(void)
+{
+  ARR_DestroyInstance(recv_sck_messages);
+  ARR_DestroyInstance(recv_headers);
+  ARR_DestroyInstance(recv_messages);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+
+int
+SCK_IsIpFamilyEnabled(int family)
+{
+  switch (family) {
+    case IPADDR_INET4:
+      return ip4_enabled;
+    case IPADDR_INET6:
+      return ip6_enabled;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_GetAnyLocalIPAddress(int family, IPAddr *local_addr)
+{
+  local_addr->family = family;
+
+  switch (family) {
+    case IPADDR_INET4:
+      local_addr->addr.in4 = INADDR_ANY;
+      break;
+    case IPADDR_INET6:
+#ifdef FEAT_IPV6
+      memcpy(&local_addr->addr.in6, &in6addr_any, sizeof (local_addr->addr.in6));
+#else
+      memset(&local_addr->addr.in6, 0, sizeof (local_addr->addr.in6));
+#endif
+      break;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_GetLoopbackIPAddress(int family, IPAddr *local_addr)
+{
+  local_addr->family = family;
+
+  switch (family) {
+    case IPADDR_INET4:
+      local_addr->addr.in4 = INADDR_LOOPBACK;
+      break;
+    case IPADDR_INET6:
+#ifdef FEAT_IPV6
+      memcpy(&local_addr->addr.in6, &in6addr_loopback, sizeof (local_addr->addr.in6));
+#else
+      memset(&local_addr->addr.in6, 0, sizeof (local_addr->addr.in6));
+      local_addr->addr.in6[15] = 1;
+#endif
+      break;
+  }
+}
+
+/* ================================================== */
+
+int
+SCK_IsLinkLocalIPAddress(IPAddr *addr)
+{
+  switch (addr->family) {
+    case IPADDR_INET4:
+      /* 169.254.0.0/16 */
+      return (addr->addr.in4 & 0xffff0000) == 0xa9fe0000;
+    case IPADDR_INET6:
+      /* fe80::/10 */
+      return addr->addr.in6[0] == 0xfe && (addr->addr.in6[1] & 0xc0) == 0x80;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+void
+SCK_SetPrivBind(int (*function)(int sock_fd, struct sockaddr *address,
+                                socklen_t address_len))
+{
+  priv_bind_function = function;
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUdpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface, int flags)
+{
+  return open_ip_socket(remote_addr, local_addr, iface, SOCK_DGRAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenTcpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr, const char *iface, int flags)
+{
+  return open_ip_socket(remote_addr, local_addr, iface, SOCK_STREAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixDatagramSocket(const char *remote_addr, const char *local_addr, int flags)
+{
+  return open_unix_socket(remote_addr, local_addr, SOCK_DGRAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixStreamSocket(const char *remote_addr, const char *local_addr, int flags)
+{
+  return open_unix_socket(remote_addr, local_addr, SOCK_STREAM, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_OpenUnixSocketPair(int flags, int *other_fd)
+{
+  int sock_fd;
+
+  /* Prefer SEQPACKET sockets over DGRAM in order to receive a zero-length
+     message (end of file) when the other end is unexpectedly closed */
+  if (
+#ifdef SOCK_SEQPACKET
+      (sock_fd = open_unix_socket_pair(SOCK_SEQPACKET, flags, other_fd)) < 0 &&
+#endif
+      (sock_fd = open_unix_socket_pair(SOCK_DGRAM, flags, other_fd)) < 0)
+    return INVALID_SOCK_FD;
+
+  return sock_fd;
+}
+
+/* ================================================== */
+
+int
+SCK_SetIntOption(int sock_fd, int level, int name, int value)
+{
+  if (setsockopt(sock_fd, level, name, &value, sizeof (value)) < 0) {
+    DEBUG_LOG("setsockopt() failed fd=%d level=%d name=%d value=%d : %s",
+              sock_fd, level, name, value, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_GetIntOption(int sock_fd, int level, int name, int *value)
+{
+  socklen_t len = sizeof (*value);
+
+  if (getsockopt(sock_fd, level, name, value, &len) < 0) {
+    DEBUG_LOG("getsockopt() failed fd=%d level=%d name=%d : %s",
+              sock_fd, level, name, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_EnableKernelRxTimestamping(int sock_fd)
+{
+#ifdef SO_TIMESTAMPNS
+  if (SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, 1))
+    return 1;
+#endif
+#ifdef SO_TIMESTAMP
+  if (SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TIMESTAMP, 1)) {
+#if defined(SO_TS_CLOCK) && defined(SO_TS_REALTIME)
+    /* We don't care about the return value - we'll get either a
+       SCM_REALTIME (if we succeded) or a SCM_TIMESTAMP (if we failed) */
+    if (!SCK_SetIntOption(sock_fd, SOL_SOCKET, SO_TS_CLOCK, SO_TS_REALTIME))
+      ;
+#endif
+    return 1;
+  }
+#endif
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+SCK_ListenOnSocket(int sock_fd, int backlog)
+{
+  if (listen(sock_fd, backlog) < 0) {
+    DEBUG_LOG("listen() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_AcceptConnection(int sock_fd, IPSockAddr *remote_addr)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len = sizeof (saddr);
+  int conn_fd;
+
+  conn_fd = accept(sock_fd, &saddr.sa, &saddr_len);
+  if (conn_fd < 0) {
+    DEBUG_LOG("accept() failed : %s", strerror(errno));
+    return INVALID_SOCK_FD;
+  }
+
+  if (!UTI_FdSetCloexec(conn_fd) || !set_socket_nonblock(conn_fd)) {
+    close(conn_fd);
+    return INVALID_SOCK_FD;
+  }
+
+  SCK_SockaddrToIPSockAddr(&saddr.sa, saddr_len, remote_addr);
+
+  return conn_fd;
+}
+
+/* ================================================== */
+
+int
+SCK_ShutdownConnection(int sock_fd)
+{
+  if (shutdown(sock_fd, SHUT_RDWR) < 0) {
+    DEBUG_LOG("shutdown() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SCK_Receive(int sock_fd, void *buffer, int length, int flags)
+{
+  int r;
+
+  if (length < 0) {
+    DEBUG_LOG("Invalid length %d", length);
+    return -1;
+  }
+
+  r = recv(sock_fd, buffer, length, get_recv_flags(flags));
+
+  if (r < 0) {
+    handle_recv_error(sock_fd, flags);
+    return r;
+  }
+
+  DEBUG_LOG("Received data fd=%d len=%d", sock_fd, r);
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+SCK_Send(int sock_fd, const void *buffer, int length, int flags)
+{
+  int r;
+
+  assert(flags == 0);
+
+  if (length < 0) {
+    DEBUG_LOG("Invalid length %d", length);
+    return -1;
+  }
+
+  r = send(sock_fd, buffer, length, 0);
+
+  if (r < 0) {
+    DEBUG_LOG("Could not send data fd=%d len=%d : %s", sock_fd, length, strerror(errno));
+    return r;
+  }
+
+  DEBUG_LOG("Sent data fd=%d len=%d", sock_fd, r);
+
+  return r;
+}
+
+/* ================================================== */
+
+SCK_Message *
+SCK_ReceiveMessage(int sock_fd, int flags)
+{
+  int num_messages;
+
+  return receive_messages(sock_fd, flags, 1, &num_messages);
+}
+
+/* ================================================== */
+
+SCK_Message *
+SCK_ReceiveMessages(int sock_fd, int flags, int *num_messages)
+{
+  return receive_messages(sock_fd, flags, MAX_RECV_MESSAGES, num_messages);
+}
+
+/* ================================================== */
+
+void
+SCK_InitMessage(SCK_Message *message, SCK_AddressType addr_type)
+{
+  init_message_addresses(message, addr_type);
+  init_message_nonaddress(message);
+}
+
+/* ================================================== */
+
+int
+SCK_SendMessage(int sock_fd, SCK_Message *message, int flags)
+{
+  return send_message(sock_fd, message, flags);
+}
+
+/* ================================================== */
+
+int
+SCK_RemoveSocket(int sock_fd)
+{
+  union sockaddr_all saddr;
+  socklen_t saddr_len;
+
+  saddr_len = sizeof (saddr);
+
+  if (getsockname(sock_fd, &saddr.sa, &saddr_len) < 0) {
+    DEBUG_LOG("getsockname() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  if (saddr_len > sizeof (saddr) || saddr_len <= sizeof (saddr.sa.sa_family) ||
+      saddr.sa.sa_family != AF_UNIX)
+    return 0;
+
+  if (unlink(saddr.un.sun_path) < 0) {
+    DEBUG_LOG("Could not remove %s : %s", saddr.un.sun_path, strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SCK_CloseSocket(int sock_fd)
+{
+  close(sock_fd);
+}
+
+/* ================================================== */
+
+void
+SCK_SockaddrToIPSockAddr(struct sockaddr *sa, int sa_length, IPSockAddr *ip_sa)
+{
+  ip_sa->ip_addr.family = IPADDR_UNSPEC;
+  ip_sa->port = 0;
+
+  switch (sa->sa_family) {
+    case AF_INET:
+      if (sa_length < (int)sizeof (struct sockaddr_in))
+        return;
+      ip_sa->ip_addr.family = IPADDR_INET4;
+      ip_sa->ip_addr.addr.in4 = ntohl(((struct sockaddr_in *)sa)->sin_addr.s_addr);
+      ip_sa->port = ntohs(((struct sockaddr_in *)sa)->sin_port);
+      break;
+#ifdef FEAT_IPV6
+    case AF_INET6:
+      if (sa_length < (int)sizeof (struct sockaddr_in6))
+        return;
+      ip_sa->ip_addr.family = IPADDR_INET6;
+      memcpy(&ip_sa->ip_addr.addr.in6, ((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr,
+             sizeof (ip_sa->ip_addr.addr.in6));
+      ip_sa->port = ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
+      break;
+#endif
+    default:
+      break;
+  }
+}
+
+/* ================================================== */
+
+int
+SCK_IPSockAddrToSockaddr(IPSockAddr *ip_sa, struct sockaddr *sa, int sa_length)
+{
+  switch (ip_sa->ip_addr.family) {
+    case IPADDR_INET4:
+      if (sa_length < (int)sizeof (struct sockaddr_in))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr_in));
+      sa->sa_family = AF_INET;
+      ((struct sockaddr_in *)sa)->sin_addr.s_addr = htonl(ip_sa->ip_addr.addr.in4);
+      ((struct sockaddr_in *)sa)->sin_port = htons(ip_sa->port);
+#ifdef SIN6_LEN
+      ((struct sockaddr_in *)sa)->sin_len = sizeof (struct sockaddr_in);
+#endif
+      return sizeof (struct sockaddr_in);
+#ifdef FEAT_IPV6
+    case IPADDR_INET6:
+      if (sa_length < (int)sizeof (struct sockaddr_in6))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr_in6));
+      sa->sa_family = AF_INET6;
+      memcpy(&((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr, ip_sa->ip_addr.addr.in6,
+             sizeof (((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr));
+      ((struct sockaddr_in6 *)sa)->sin6_port = htons(ip_sa->port);
+#ifdef SIN6_LEN
+      ((struct sockaddr_in6 *)sa)->sin6_len = sizeof (struct sockaddr_in6);
+#endif
+      return sizeof (struct sockaddr_in6);
+#endif
+    default:
+      if (sa_length < (int)sizeof (struct sockaddr))
+        return 0;
+      memset(sa, 0, sizeof (struct sockaddr));
+      sa->sa_family = AF_UNSPEC;
+      return 0;
+  }
+}
diff --git a/socket.h b/socket.h
new file mode 100644
index 0000000..cdbae2d
--- /dev/null
+++ b/socket.h
@@ -0,0 +1,147 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for socket operations.
+
+  */
+
+#ifndef GOT_SOCKET_H
+#define GOT_SOCKET_H
+
+#include "addressing.h"
+
+/* Flags for opening sockets */
+#define SCK_FLAG_BLOCK 1
+#define SCK_FLAG_BROADCAST 2
+#define SCK_FLAG_RX_DEST_ADDR 4
+#define SCK_FLAG_ALL_PERMISSIONS 8
+#define SCK_FLAG_PRIV_BIND 16
+
+/* Flags for receiving and sending messages */
+#define SCK_FLAG_MSG_ERRQUEUE 1
+#define SCK_FLAG_MSG_DESCRIPTOR 2
+
+typedef enum {
+  SCK_ADDR_UNSPEC = 0,
+  SCK_ADDR_IP,
+  SCK_ADDR_UNIX
+} SCK_AddressType;
+
+typedef struct {
+  void *data;
+  int length;
+  SCK_AddressType addr_type;
+  int if_index;
+
+  union {
+    IPSockAddr ip;
+    const char *path;
+  } remote_addr;
+
+  union {
+    IPAddr ip;
+  } local_addr;
+
+  struct {
+    struct timespec kernel;
+    struct timespec hw;
+    int if_index;
+    int l2_length;
+    int tx_flags;
+  } timestamp;
+
+  int descriptor;
+} SCK_Message;
+
+/* Initialisation function (the specified IP family is enabled,
+   or all if IPADDR_UNSPEC) */
+extern void SCK_Initialise(int family);
+
+/* Finalisation function */
+extern void SCK_Finalise(void);
+
+/* Check if support for the IP family is enabled */
+extern int SCK_IsIpFamilyEnabled(int family);
+
+/* Get the 0.0.0.0/::0 or 127.0.0.1/::1 address */
+extern void SCK_GetAnyLocalIPAddress(int family, IPAddr *local_addr);
+extern void SCK_GetLoopbackIPAddress(int family, IPAddr *local_addr);
+
+/* Check if an IP address is a link-local address */
+extern int SCK_IsLinkLocalIPAddress(IPAddr *addr);
+
+/* Specify a bind()-like function for binding sockets to privileged ports when
+   running in a restricted process (e.g. after dropping root privileges) */
+extern void SCK_SetPrivBind(int (*function)(int sock_fd, struct sockaddr *address,
+                                            socklen_t address_len));
+
+/* Open a socket (addresses and iface may be NULL) */
+extern int SCK_OpenUdpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr,
+                             const char *iface, int flags);
+extern int SCK_OpenTcpSocket(IPSockAddr *remote_addr, IPSockAddr *local_addr,
+                             const char *iface, int flags);
+extern int SCK_OpenUnixDatagramSocket(const char *remote_addr, const char *local_addr,
+                                      int flags);
+extern int SCK_OpenUnixStreamSocket(const char *remote_addr, const char *local_addr,
+                                    int flags);
+extern int SCK_OpenUnixSocketPair(int flags, int *other_fd);
+
+/* Set and get a socket option of int size */
+extern int SCK_SetIntOption(int sock_fd, int level, int name, int value);
+extern int SCK_GetIntOption(int sock_fd, int level, int name, int *value);
+
+/* Enable RX timestamping socket option */
+extern int SCK_EnableKernelRxTimestamping(int sock_fd);
+
+/* Operate on a stream socket - listen()/accept()/shutdown() wrappers */
+extern int SCK_ListenOnSocket(int sock_fd, int backlog);
+extern int SCK_AcceptConnection(int sock_fd, IPSockAddr *remote_addr);
+extern int SCK_ShutdownConnection(int sock_fd);
+
+/* Receive and send data on connected sockets - recv()/send() wrappers */
+extern int SCK_Receive(int sock_fd, void *buffer, int length, int flags);
+extern int SCK_Send(int sock_fd, const void *buffer, int length, int flags);
+
+/* Receive a single message or multiple messages.  The functions return
+   a pointer to static buffers, or NULL on error.  The buffers are valid until
+   another call of the functions and can be reused for sending messages. */
+extern SCK_Message *SCK_ReceiveMessage(int sock_fd, int flags);
+extern SCK_Message *SCK_ReceiveMessages(int sock_fd, int flags, int *num_messages);
+
+/* Initialise a new message (e.g. before sending) */
+extern void SCK_InitMessage(SCK_Message *message, SCK_AddressType addr_type);
+
+/* Send a message */
+extern int SCK_SendMessage(int sock_fd, SCK_Message *message, int flags);
+
+/* Remove bound Unix socket */
+extern int SCK_RemoveSocket(int sock_fd);
+
+/* Close the socket */
+extern void SCK_CloseSocket(int sock_fd);
+
+/* Convert between IPSockAddr and sockaddr_in/in6 */
+extern void SCK_SockaddrToIPSockAddr(struct sockaddr *sa, int sa_length, IPSockAddr *ip_sa);
+extern int SCK_IPSockAddrToSockaddr(IPSockAddr *ip_sa, struct sockaddr *sa, int sa_length);
+
+#endif
diff --git a/sources.c b/sources.c
new file mode 100644
index 0000000..e8e9705
--- /dev/null
+++ b/sources.c
@@ -0,0 +1,1854 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2016, 2018, 2020-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The routines in this file manage the complete pool of sources that
+  we might be synchronizing to.  This includes NTP sources and others
+  (e.g. local reference clocks, eyeball + wristwatch etc).
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sources.h"
+#include "sourcestats.h"
+#include "memory.h"
+#include "ntp.h" /* For NTP_Leap */
+#include "ntp_sources.h"
+#include "local.h"
+#include "reference.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "reports.h"
+#include "nameserv.h"
+#include "sched.h"
+#include "regress.h"
+
+/* ================================================== */
+/* Flag indicating that we are initialised */
+static int initialised = 0;
+
+/* ================================================== */
+/* Structure used to hold info for selecting between sources */
+struct SelectInfo {
+  int select_ok;
+  double std_dev;
+  double root_distance;
+  double lo_limit;
+  double hi_limit;
+  double last_sample_ago;
+};
+
+/* ================================================== */
+/* This enum contains the flag values that are used to label
+   each source */
+typedef enum {
+  SRC_OK,               /* OK so far, not a final status! */
+  SRC_UNSELECTABLE,     /* Has noselect option set */
+  SRC_UNSYNCHRONISED,   /* Provides samples but not unsynchronised */
+  SRC_BAD_STATS,        /* Doesn't have valid stats data */
+  SRC_BAD_DISTANCE,     /* Has root distance longer than allowed maximum */
+  SRC_JITTERY,          /* Had std dev larger than allowed maximum */
+  SRC_WAITS_STATS,      /* Others have bad stats, selection postponed */
+  SRC_STALE,            /* Has older samples than others */
+  SRC_ORPHAN,           /* Has stratum equal or larger than orphan stratum */
+  SRC_UNTRUSTED,        /* Overlaps trusted sources */
+  SRC_FALSETICKER,      /* Doesn't agree with others */
+  SRC_WAITS_SOURCES,    /* Not enough sources, selection postponed */
+  SRC_NONPREFERRED,     /* Others have prefer option */
+  SRC_WAITS_UPDATE,     /* No updates, selection postponed */
+  SRC_DISTANT,          /* Others have shorter root distance */
+  SRC_OUTLIER,          /* Outlier in clustering (not used yet) */
+  SRC_UNSELECTED,       /* Used for synchronisation, not system peer */
+  SRC_SELECTED,         /* Used for synchronisation, selected as system peer */
+} SRC_Status;
+
+/* ================================================== */
+/* Define the instance structure used to hold information about each
+   source */
+struct SRC_Instance_Record {
+  SST_Stats stats;
+  int index;                    /* Index back into the array of source */
+  uint32_t ref_id;              /* The reference ID of this source
+                                   (i.e. from its IP address, NOT the
+                                   reference _it_ is sync'd to) */
+  IPAddr *ip_addr;              /* Its IP address if NTP source */
+
+  /* Flag indicating that the source is updating reachability */
+  int active;
+
+  /* Reachability register */
+  int reachability;
+
+  /* Number of set bits in the reachability register */
+  int reachability_size;
+
+  /* Updates since last reference update */
+  int updates;
+
+  /* Updates left before allowing combining */
+  int distant;
+
+  /* Updates with a status requiring source replacement */
+  int bad;
+
+  /* Flag indicating the status of the source */
+  SRC_Status status;
+
+  /* Type of the source */
+  SRC_Type type;
+
+  /* Flag indicating that the source is authenticated */
+  int authenticated;
+
+  /* Configured selection options */
+  int conf_sel_options;
+
+  /* Effective selection options */
+  int sel_options;
+
+  /* Score against currently selected source */
+  double sel_score;
+
+  struct SelectInfo sel_info;
+
+  /* Current stratum */
+  int stratum;
+
+  /* Current leap status */
+  NTP_Leap leap;
+
+  /* Flag indicating the source has a leap second vote */
+  int leap_vote;
+
+  /* Flag indicating the source was already reported as
+     a falseticker since the last selection change */
+  int reported_falseticker;
+};
+
+/* ================================================== */
+/* Structure used to build the sort list for finding falsetickers */
+struct Sort_Element {
+  int index;
+  double offset;
+  enum {
+    LOW = -1,
+    HIGH = 1
+  } tag;
+};
+
+/* ================================================== */
+/* Table of sources */
+static struct SRC_Instance_Record **sources;
+static struct Sort_Element *sort_list;
+static int *sel_sources;
+static int n_sources; /* Number of sources currently in the table */
+static int max_n_sources; /* Capacity of the table */
+
+#define INVALID_SOURCE (-1)
+static int selected_source_index; /* Which source index is currently
+                                     selected (set to INVALID_SOURCE
+                                     if no current valid reference) */
+static int reported_no_majority;  /* Flag to avoid repeated log message
+                                     about no majority */
+
+/* Score needed to replace the currently selected source */
+#define SCORE_LIMIT 10.0
+
+/* Number of updates needed to reset the distant status */
+#define DISTANT_PENALTY 32
+
+/* Number of updates needed to trigger handling of bad sources */
+#define BAD_HANDLE_THRESHOLD 4
+
+static double max_distance;
+static double max_jitter;
+static double reselect_distance;
+static double stratum_weight;
+static double combine_limit;
+
+static SRC_Instance last_updated_inst;
+
+static LOG_FileID logfileid;
+
+/* Identifier of the dump file */
+#define DUMP_IDENTIFIER "SRC0\n"
+
+/* ================================================== */
+/* Forward prototype */
+
+static void update_sel_options(void);
+static void slew_sources(struct timespec *raw, struct timespec *cooked, double dfreq,
+                         double doffset, LCL_ChangeType change_type, void *anything);
+static void add_dispersion(double dispersion, void *anything);
+static char *source_to_string(SRC_Instance inst);
+static char get_status_char(SRC_Status status);
+
+/* ================================================== */
+/* Initialisation function */
+void SRC_Initialise(void) {
+  sources = NULL;
+  sort_list = NULL;
+  sel_sources = NULL;
+  n_sources = 0;
+  max_n_sources = 0;
+  selected_source_index = INVALID_SOURCE;
+  max_distance = CNF_GetMaxDistance();
+  max_jitter = CNF_GetMaxJitter();
+  reselect_distance = CNF_GetReselectDistance();
+  stratum_weight = CNF_GetStratumWeight();
+  combine_limit = CNF_GetCombineLimit();
+  initialised = 1;
+
+  LCL_AddParameterChangeHandler(slew_sources, NULL);
+  LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
+
+  last_updated_inst = NULL;
+
+  logfileid = CNF_GetLogSelection() ? LOG_FileOpen("selection",
+              "   Date (UTC) Time     IP Address   S EOpts Reach Score Last sample  Low end   High end")
+              : -1;
+}
+
+/* ================================================== */
+/* Finalisation function */
+void SRC_Finalise(void)
+{
+  LCL_RemoveParameterChangeHandler(slew_sources, NULL);
+  LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
+
+  Free(sources);
+  Free(sort_list);
+  Free(sel_sources);
+
+  initialised = 0;
+}
+
+/* ================================================== */
+/* Function to create a new instance.  This would be called by one of
+   the individual source-type instance creation routines. */
+
+SRC_Instance SRC_CreateNewInstance(uint32_t ref_id, SRC_Type type, int authenticated,
+                                   int sel_options, IPAddr *addr, int min_samples,
+                                   int max_samples, double min_delay, double asymmetry)
+{
+  SRC_Instance result;
+
+  assert(initialised);
+
+  if (min_samples == SRC_DEFAULT_MINSAMPLES)
+    min_samples = CNF_GetMinSamples();
+  if (max_samples == SRC_DEFAULT_MAXSAMPLES)
+    max_samples = CNF_GetMaxSamples();
+
+  result = MallocNew(struct SRC_Instance_Record);
+  result->stats = SST_CreateInstance(ref_id, addr, min_samples, max_samples,
+                                     min_delay, asymmetry);
+
+  if (n_sources == max_n_sources) {
+    /* Reallocate memory */
+    max_n_sources = max_n_sources > 0 ? 2 * max_n_sources : 4;
+    if (sources) {
+      sources = ReallocArray(struct SRC_Instance_Record *, max_n_sources, sources);
+      sort_list = ReallocArray(struct Sort_Element, 3*max_n_sources, sort_list);
+      sel_sources = ReallocArray(int, max_n_sources, sel_sources);
+    } else {
+      sources = MallocArray(struct SRC_Instance_Record *, max_n_sources);
+      sort_list = MallocArray(struct Sort_Element, 3*max_n_sources);
+      sel_sources = MallocArray(int, max_n_sources);
+    }
+  }
+
+  sources[n_sources] = result;
+
+  result->index = n_sources;
+  result->type = type;
+  result->authenticated = authenticated;
+  result->conf_sel_options = sel_options;
+  result->sel_options = sel_options;
+  result->active = 0;
+
+  SRC_SetRefid(result, ref_id, addr);
+  SRC_ResetInstance(result);
+
+  n_sources++;
+
+  update_sel_options();
+
+  return result;
+}
+
+/* ================================================== */
+/* Function to get rid of a source when it is being unconfigured.
+   This may cause the current reference source to be reselected, if this
+   was the reference source or contributed significantly to a
+   falseticker decision. */
+
+void SRC_DestroyInstance(SRC_Instance instance)
+{
+  int dead_index, i;
+
+  if (last_updated_inst == instance)
+    last_updated_inst = NULL;
+
+  assert(initialised);
+  if (instance->index < 0 || instance->index >= n_sources ||
+      instance != sources[instance->index])
+    assert(0);
+
+  SST_DeleteInstance(instance->stats);
+  dead_index = instance->index;
+  for (i=dead_index; i<n_sources-1; i++) {
+    sources[i] = sources[i+1];
+    sources[i]->index = i;
+  }
+  --n_sources;
+  Free(instance);
+
+  update_sel_options();
+
+  /* If this was the previous reference source, we have to reselect! */
+  if (selected_source_index == dead_index)
+    SRC_ReselectSource();
+  else if (selected_source_index > dead_index)
+    --selected_source_index;
+}
+
+/* ================================================== */
+
+void
+SRC_ResetInstance(SRC_Instance instance)
+{
+  instance->updates = 0;
+  instance->reachability = 0;
+  instance->reachability_size = 0;
+  instance->distant = 0;
+  instance->bad = 0;
+  instance->status = SRC_BAD_STATS;
+  instance->sel_score = 1.0;
+  instance->stratum = 0;
+  instance->leap = LEAP_Unsynchronised;
+  instance->leap_vote = 0;
+  instance->reported_falseticker = 0;
+
+  memset(&instance->sel_info, 0, sizeof (instance->sel_info));
+
+  SST_ResetInstance(instance->stats);
+}
+
+/* ================================================== */
+
+void
+SRC_SetRefid(SRC_Instance instance, uint32_t ref_id, IPAddr *addr)
+{
+  instance->ref_id = ref_id;
+  instance->ip_addr = addr;
+  SST_SetRefid(instance->stats, ref_id, addr);
+}
+
+/* ================================================== */
+
+SST_Stats
+SRC_GetSourcestats(SRC_Instance instance)
+{
+  assert(initialised);
+  return instance->stats;
+}
+
+/* ================================================== */
+
+static NTP_Leap
+get_leap_status(void)
+{
+  int i, leap_votes, leap_ins, leap_del;
+
+  /* Accept a leap second if more than half of the sources with a vote agree */
+
+  for (i = leap_ins = leap_del = leap_votes = 0; i < n_sources; i++) {
+    if (!sources[i]->leap_vote)
+      continue;
+
+    leap_votes++;
+    if (sources[i]->leap == LEAP_InsertSecond)
+      leap_ins++;
+    else if (sources[i]->leap == LEAP_DeleteSecond)
+      leap_del++;
+  }
+
+  if (leap_ins > leap_votes / 2)
+    return LEAP_InsertSecond;
+  else if (leap_del > leap_votes / 2)
+    return LEAP_DeleteSecond;
+  else
+    return LEAP_Normal;
+}
+
+/* ================================================== */
+
+void
+SRC_UpdateStatus(SRC_Instance inst, int stratum, NTP_Leap leap)
+{
+  inst->stratum = stratum;
+
+  if (REF_IsLeapSecondClose(NULL, 0.0))
+    return;
+
+  inst->leap = leap;
+
+  if (inst->leap_vote)
+    REF_UpdateLeapStatus(get_leap_status());
+}
+
+/* ================================================== */
+
+/* This function is called by one of the source drivers when it has
+   a new sample that is to be accumulated.
+
+   This function causes the frequency estimation to be re-run for the
+   designated source, and the clock selection procedure to be re-run
+   afterwards.
+   */
+
+void
+SRC_AccumulateSample(SRC_Instance inst, NTP_Sample *sample)
+{
+
+  assert(initialised);
+
+  DEBUG_LOG("src=%s ts=%s offset=%e delay=%e disp=%e",
+            source_to_string(inst), UTI_TimespecToString(&sample->time), -sample->offset,
+            sample->root_delay, sample->root_dispersion);
+
+  if (REF_IsLeapSecondClose(&sample->time, sample->offset)) {
+    LOG(LOGS_INFO, "Dropping sample around leap second");
+    return;
+  }
+
+  SST_AccumulateSample(inst->stats, sample);
+  SST_DoNewRegression(inst->stats);
+}
+
+/* ================================================== */
+
+void
+SRC_SetActive(SRC_Instance inst)
+{
+  inst->active = 1;
+}
+
+/* ================================================== */
+
+void
+SRC_UnsetActive(SRC_Instance inst)
+{
+  inst->active = 0;
+}
+
+/* ================================================== */
+
+static int
+special_mode_end(void)
+{
+    int i;
+
+    for (i = 0; i < n_sources; i++) {
+      /* No updates from inactive sources */
+      if (!sources[i]->active)
+        continue;
+
+      /* Don't expect more updates than the initial burst of an NTP source */
+      if (sources[i]->reachability_size >= SOURCE_REACH_BITS - 1)
+        continue;
+
+      /* Check if the source could still have enough samples to be selectable */
+      if (SOURCE_REACH_BITS - 1 - sources[i]->reachability_size +
+            SST_Samples(sources[i]->stats) >= MIN_SAMPLES_FOR_REGRESS)
+        return 0;
+    }
+
+    return 1;
+}
+
+/* ================================================== */
+
+static void
+handle_bad_source(SRC_Instance inst)
+{
+  if (inst->type == SRC_NTP) {
+    DEBUG_LOG("Bad source status=%c", get_status_char(inst->status));
+    NSR_HandleBadSource(inst->ip_addr);
+  }
+}
+
+/* ================================================== */
+
+void
+SRC_UpdateReachability(SRC_Instance inst, int reachable)
+{
+  inst->reachability <<= 1;
+  inst->reachability |= !!reachable;
+  inst->reachability %= 1U << SOURCE_REACH_BITS;
+
+  if (inst->reachability_size < SOURCE_REACH_BITS)
+      inst->reachability_size++;
+
+  if (!reachable && inst->index == selected_source_index) {
+    /* Try to select a better source */
+    SRC_SelectSource(NULL);
+  }
+
+  /* Check if special reference update mode failed */
+  if (REF_GetMode() != REF_ModeNormal && special_mode_end()) {
+    REF_SetUnsynchronised();
+  }
+
+  /* Try to replace unreachable NTP sources */
+  if (inst->reachability == 0 && inst->reachability_size == SOURCE_REACH_BITS)
+    handle_bad_source(inst);
+}
+
+/* ================================================== */
+
+void
+SRC_ResetReachability(SRC_Instance inst)
+{
+  inst->reachability = 0;
+  inst->reachability_size = 0;
+  SRC_UpdateReachability(inst, 0);
+}
+
+/* ================================================== */
+
+static void
+update_sel_options(void)
+{
+  int options, auth_ntp_options, unauth_ntp_options, refclk_options;
+  int i, auth_ntp_sources, unauth_ntp_sources;
+
+  auth_ntp_sources = unauth_ntp_sources = 0;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->conf_sel_options & SRC_SELECT_NOSELECT)
+      continue;
+    if (sources[i]->type != SRC_NTP)
+      continue;
+    if (sources[i]->authenticated)
+      auth_ntp_sources++;
+    else
+      unauth_ntp_sources++;
+  }
+
+  auth_ntp_options = unauth_ntp_options = refclk_options = 0;
+
+  /* Determine which selection options need to be added to authenticated NTP
+     sources, unauthenticated NTP sources, and refclocks, to follow the
+     configured selection mode */
+  switch (CNF_GetAuthSelectMode()) {
+    case SRC_AUTHSELECT_IGNORE:
+      break;
+    case SRC_AUTHSELECT_MIX:
+      if (auth_ntp_sources > 0 && unauth_ntp_sources > 0)
+        auth_ntp_options = refclk_options = SRC_SELECT_REQUIRE | SRC_SELECT_TRUST;
+      break;
+    case SRC_AUTHSELECT_PREFER:
+      if (auth_ntp_sources > 0)
+        unauth_ntp_options = SRC_SELECT_NOSELECT;
+      break;
+    case SRC_AUTHSELECT_REQUIRE:
+      unauth_ntp_options = SRC_SELECT_NOSELECT;
+      break;
+    default:
+      assert(0);
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    options = sources[i]->conf_sel_options;
+
+    if (!(options & SRC_SELECT_NOSELECT)) {
+      switch (sources[i]->type) {
+        case SRC_NTP:
+          options |= sources[i]->authenticated ? auth_ntp_options : unauth_ntp_options;
+          break;
+        case SRC_REFCLOCK:
+          options |= refclk_options;
+          break;
+        default:
+          assert(0);
+      }
+    }
+
+    if (sources[i]->sel_options != options) {
+      DEBUG_LOG("changing %s from %x to %x", source_to_string(sources[i]),
+                (unsigned int)sources[i]->sel_options, (unsigned int)options);
+      sources[i]->sel_options = options;
+    }
+  }
+}
+
+/* ================================================== */
+
+static void
+log_selection_message(LOG_Severity severity, const char *format, const char *arg)
+{
+  if (REF_GetMode() != REF_ModeNormal)
+    return;
+  LOG(severity, format, arg);
+}
+
+/* ================================================== */
+
+static void
+log_selection_source(LOG_Severity severity, const char *format, SRC_Instance inst)
+{
+  char buf[320], *name, *ntp_name;
+
+  name = source_to_string(inst);
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : NULL;
+
+  if (ntp_name && strcmp(name, ntp_name) != 0)
+    snprintf(buf, sizeof (buf), "%s (%s)", name, ntp_name);
+  else
+    snprintf(buf, sizeof (buf), "%s", name);
+
+  log_selection_message(severity, format, buf);
+}
+
+/* ================================================== */
+
+static int
+compare_sort_elements(const void *a, const void *b)
+{
+  const struct Sort_Element *u = (const struct Sort_Element *) a;
+  const struct Sort_Element *v = (const struct Sort_Element *) b;
+
+  if (u->offset < v->offset) {
+    return -1;
+  } else if (u->offset > v->offset) {
+    return +1;
+  } else if (u->tag < v->tag) {
+    return -1;
+  } else if (u->tag > v->tag) {
+    return +1;
+  } else {
+    return 0;
+  }
+}
+
+/* ================================================== */
+
+static char *
+source_to_string(SRC_Instance inst)
+{
+  switch (inst->type) {
+    case SRC_NTP:
+      return UTI_IPToString(inst->ip_addr);
+    case SRC_REFCLOCK:
+      return UTI_RefidToString(inst->ref_id);
+    default:
+      assert(0);
+  }
+  return NULL;
+}
+
+/* ================================================== */
+
+static void
+mark_source(SRC_Instance inst, SRC_Status status)
+{
+  struct timespec now;
+
+  inst->status = status;
+
+  /* Try to replace NTP sources that are falsetickers, or have a root
+     distance or jitter larger than the allowed maximums */
+  if (inst == last_updated_inst) {
+    if (inst->bad < INT_MAX &&
+        (status == SRC_FALSETICKER || status == SRC_BAD_DISTANCE || status == SRC_JITTERY))
+      inst->bad++;
+    else
+      inst->bad = 0;
+    if (inst->bad >= BAD_HANDLE_THRESHOLD)
+      handle_bad_source(inst);
+  }
+
+  DEBUG_LOG("%s status=%c options=%x reach=%o/%d updates=%d distant=%d bad=%d leap=%d vote=%d lo=%f hi=%f",
+            source_to_string(inst), get_status_char(inst->status),
+            (unsigned int)inst->sel_options, (unsigned int)inst->reachability,
+            inst->reachability_size, inst->updates,
+            inst->distant, inst->bad, (int)inst->leap, inst->leap_vote,
+            inst->sel_info.lo_limit, inst->sel_info.hi_limit);
+
+  if (logfileid == -1)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  LOG_FileWrite(logfileid,
+                "%s %-15s %c -%c%c%c%c %4o %5.2f %10.3e %10.3e %10.3e",
+                UTI_TimeToLogForm(now.tv_sec), source_to_string(inst),
+                get_status_char(inst->status),
+                inst->sel_options & SRC_SELECT_NOSELECT ? 'N' : '-',
+                inst->sel_options & SRC_SELECT_PREFER ? 'P' : '-',
+                inst->sel_options & SRC_SELECT_TRUST ? 'T' : '-',
+                inst->sel_options & SRC_SELECT_REQUIRE ? 'R' : '-',
+                (unsigned int)inst->reachability, inst->sel_score,
+                inst->sel_info.last_sample_ago,
+                inst->sel_info.lo_limit, inst->sel_info.hi_limit);
+}
+
+/* ================================================== */
+
+static void
+mark_ok_sources(SRC_Status status)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+    mark_source(sources[i], status);
+  }
+}
+
+/* ================================================== */
+
+static int
+combine_sources(int n_sel_sources, struct timespec *ref_time, double *offset,
+                double *offset_sd, double *frequency, double *frequency_sd, double *skew)
+{
+  struct timespec src_ref_time;
+  double src_offset, src_offset_sd, src_frequency, src_frequency_sd, src_skew;
+  double src_root_delay, src_root_dispersion, sel_src_distance, elapsed;
+  double offset_weight, sum_offset_weight, sum_offset, sum2_offset_sd;
+  double frequency_weight, sum_frequency_weight, sum_frequency;
+  double inv_sum2_frequency_sd, inv_sum2_skew;
+  int i, index, combined;
+
+  if (n_sel_sources == 1)
+    return 1;
+
+  sum_offset_weight = sum_offset = sum2_offset_sd = 0.0;
+  sum_frequency_weight = sum_frequency = inv_sum2_frequency_sd = inv_sum2_skew = 0.0;
+
+  sel_src_distance = sources[selected_source_index]->sel_info.root_distance;
+  if (sources[selected_source_index]->type == SRC_NTP)
+    sel_src_distance += reselect_distance;
+
+  for (i = combined = 0; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    SST_GetTrackingData(sources[index]->stats, &src_ref_time,
+                        &src_offset, &src_offset_sd,
+                        &src_frequency, &src_frequency_sd, &src_skew,
+                        &src_root_delay, &src_root_dispersion);
+
+    /* Don't include this source if its distance is longer than the distance of
+       the selected source multiplied by the limit, their estimated frequencies
+       are not close, or it was recently marked as distant */
+
+    if (index != selected_source_index &&
+        (sources[index]->sel_info.root_distance > combine_limit * sel_src_distance ||
+         fabs(*frequency - src_frequency) >
+           combine_limit * (*skew + src_skew + LCL_GetMaxClockError()))) {
+      /* Use a smaller penalty in first few updates */
+      sources[index]->distant = sources[index]->reachability_size >= SOURCE_REACH_BITS ?
+                                DISTANT_PENALTY : 1;
+    } else if (sources[index]->distant) {
+      sources[index]->distant--;
+    }
+
+    if (sources[index]->distant) {
+      mark_source(sources[index], SRC_DISTANT);
+      continue;
+    }
+
+    if (sources[index]->status == SRC_OK)
+      mark_source(sources[index], SRC_UNSELECTED);
+
+    elapsed = UTI_DiffTimespecsToDouble(ref_time, &src_ref_time);
+    src_offset += elapsed * src_frequency;
+    src_offset_sd += elapsed * src_frequency_sd;
+    offset_weight = 1.0 / sources[index]->sel_info.root_distance;
+    frequency_weight = 1.0 / SQUARE(src_frequency_sd);
+
+    DEBUG_LOG("combining %s oweight=%e offset=%e osd=%e fweight=%e freq=%e fsd=%e skew=%e",
+              source_to_string(sources[index]), offset_weight, src_offset, src_offset_sd,
+              frequency_weight, src_frequency, src_frequency_sd, src_skew);
+
+    sum_offset_weight += offset_weight;
+    sum_offset += offset_weight * src_offset;
+    sum2_offset_sd += offset_weight * (SQUARE(src_offset_sd) +
+                                       SQUARE(src_offset - *offset));
+
+    sum_frequency_weight += frequency_weight;
+    sum_frequency += frequency_weight * src_frequency;
+    inv_sum2_frequency_sd += 1.0 / SQUARE(src_frequency_sd);
+    inv_sum2_skew += 1.0 / SQUARE(src_skew);
+
+    combined++;
+  }
+
+  assert(combined);
+  *offset = sum_offset / sum_offset_weight;
+  *offset_sd = sqrt(sum2_offset_sd / sum_offset_weight);
+  *frequency = sum_frequency / sum_frequency_weight;
+  *frequency_sd = 1.0 / sqrt(inv_sum2_frequency_sd);
+  *skew = 1.0 / sqrt(inv_sum2_skew);
+
+  DEBUG_LOG("combined result offset=%e osd=%e freq=%e fsd=%e skew=%e",
+            *offset, *offset_sd, *frequency, *frequency_sd, *skew);
+
+  return combined;
+}
+
+/* ================================================== */
+/* This function selects the current reference from amongst the pool
+   of sources we are holding and updates the local reference */
+
+void
+SRC_SelectSource(SRC_Instance updated_inst)
+{
+  struct SelectInfo *si;
+  struct timespec now, ref_time;
+  int i, j, j1, j2, index, sel_prefer, n_endpoints, n_sel_sources, sel_req_source;
+  int n_badstats_sources, max_sel_reach, max_sel_reach_size, max_badstat_reach;
+  int depth, best_depth, trust_depth, best_trust_depth, n_sel_trust_sources;
+  int combined, stratum, min_stratum, max_score_index;
+  int orphan_stratum, orphan_source;
+  double src_offset, src_offset_sd, src_frequency, src_frequency_sd, src_skew;
+  double src_root_delay, src_root_dispersion;
+  double best_lo, best_hi, distance, sel_src_distance, max_score;
+  double best_trust_lo, best_trust_hi;
+  double first_sample_ago, max_reach_sample_ago;
+  NTP_Leap leap_status;
+
+  if (updated_inst) {
+    updated_inst->updates++;
+    last_updated_inst = updated_inst;
+  }
+
+  if (n_sources == 0) {
+    /* In this case, we clearly cannot synchronise to anything */
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message(LOGS_INFO, "Can't synchronise: no sources", NULL);
+      selected_source_index = INVALID_SOURCE;
+    }
+    return;
+  }
+
+  /* This is accurate enough and cheaper than calling LCL_ReadCookedTime */
+  SCH_GetLastEventTime(&now, NULL, NULL);
+
+  /* Step 1 - build intervals about each source */
+
+  n_endpoints = 0;
+  n_sel_sources = n_sel_trust_sources = 0;
+  n_badstats_sources = 0;
+  sel_req_source = 0;
+  max_sel_reach = max_badstat_reach = 0;
+  max_sel_reach_size = 0;
+  max_reach_sample_ago = 0.0;
+
+  for (i = 0; i < n_sources; i++) {
+    assert(sources[i]->status != SRC_OK);
+
+    /* Don't allow the source to vote on leap seconds unless it's selectable */
+    sources[i]->leap_vote = 0;
+
+    /* If some sources are specified with the require option, at least one
+       of them will have to be selectable in order to update the clock */
+    if (sources[i]->sel_options & SRC_SELECT_REQUIRE)
+      sel_req_source = 1;
+
+    /* Ignore sources which were added with the noselect option */
+    if (sources[i]->sel_options & SRC_SELECT_NOSELECT) {
+      mark_source(sources[i], SRC_UNSELECTABLE);
+      continue;
+    }
+
+    /* Ignore sources which are not synchronised */
+    if (sources[i]->leap == LEAP_Unsynchronised) {
+      mark_source(sources[i], SRC_UNSYNCHRONISED);
+      continue;
+    }
+
+    si = &sources[i]->sel_info;
+    SST_GetSelectionData(sources[i]->stats, &now,
+                         &si->lo_limit, &si->hi_limit, &si->root_distance,
+                         &si->std_dev, &first_sample_ago,
+                         &si->last_sample_ago, &si->select_ok);
+
+    if (!si->select_ok) {
+      ++n_badstats_sources;
+      mark_source(sources[i], SRC_BAD_STATS);
+      if (max_badstat_reach < sources[i]->reachability)
+        max_badstat_reach = sources[i]->reachability;
+      continue;
+    }
+
+    /* Include extra dispersion in the root distance of sources that don't
+       have new samples (the last sample is older than span of all samples) */
+    if (first_sample_ago < 2.0 * si->last_sample_ago) {
+      double extra_disp = LCL_GetMaxClockError() *
+                          (2.0 * si->last_sample_ago - first_sample_ago);
+      si->root_distance += extra_disp;
+      si->lo_limit -= extra_disp;
+      si->hi_limit += extra_disp;
+    }
+
+    /* Require the root distance to be below the allowed maximum and the
+       endpoints to be in the right order (i.e. a non-negative distance) */
+    if (!(si->root_distance <= max_distance && si->lo_limit <= si->hi_limit)) {
+      mark_source(sources[i], SRC_BAD_DISTANCE);
+      continue;
+    }
+
+    /* And the same applies for the estimated standard deviation */
+    if (si->std_dev > max_jitter) {
+      mark_source(sources[i], SRC_JITTERY);
+      continue;
+    }
+
+    sources[i]->status = SRC_OK; /* For now */
+
+    if (sources[i]->reachability && max_reach_sample_ago < first_sample_ago)
+      max_reach_sample_ago = first_sample_ago;
+
+    if (max_sel_reach < sources[i]->reachability)
+      max_sel_reach = sources[i]->reachability;
+
+    if (max_sel_reach_size < sources[i]->reachability_size)
+      max_sel_reach_size = sources[i]->reachability_size;
+  }
+
+  orphan_stratum = REF_GetOrphanStratum();
+  orphan_source = INVALID_SOURCE;
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    si = &sources[i]->sel_info;
+
+    /* Reachability is not a requirement for selection.  An unreachable source
+       can still be selected if its newest sample is not older than the oldest
+       sample from reachable sources. */
+    if (!sources[i]->reachability && max_reach_sample_ago < si->last_sample_ago) {
+      mark_source(sources[i], SRC_STALE);
+      continue;
+    }
+
+    /* When the local reference is configured with the orphan option, NTP
+       sources that have stratum equal to the configured local stratum are
+       considered to be orphans (i.e. serving local time while not being
+       synchronised with real time) and are excluded from the normal source
+       selection.  Sources with stratum larger than the local stratum are
+       considered to be directly on indirectly synchronised to an orphan and
+       are always ignored.
+
+       If no selectable source is available and all orphan sources have
+       reference IDs larger than the local ID, no source will be selected and
+       the local reference mode will be activated at some point, i.e. this host
+       will become an orphan.  Otherwise, the orphan source with the smallest
+       reference ID will be selected.  This ensures a group of servers polling
+       each other (with the same orphan configuration) which have no external
+       source can settle down to a state where only one server is serving its
+       local unsychronised time and others are synchronised to it. */
+
+    if (sources[i]->stratum >= orphan_stratum && sources[i]->type == SRC_NTP) {
+      mark_source(sources[i], SRC_ORPHAN);
+
+      if (sources[i]->stratum == orphan_stratum && sources[i]->reachability &&
+          (orphan_source == INVALID_SOURCE ||
+           sources[i]->ref_id < sources[orphan_source]->ref_id))
+        orphan_source = i;
+
+      continue;
+    }
+
+    ++n_sel_sources;
+  }
+
+  /* If no selectable source is available, consider the orphan source */
+  if (!n_sel_sources && orphan_source != INVALID_SOURCE) {
+    uint32_t local_ref_id = NSR_GetLocalRefid(sources[orphan_source]->ip_addr);
+
+    if (!local_ref_id) {
+      LOG(LOGS_ERR, "Unknown local refid in orphan mode");
+    } else if (sources[orphan_source]->ref_id < local_ref_id) {
+      sources[orphan_source]->status = SRC_OK;
+      n_sel_sources = 1;
+      DEBUG_LOG("selecting orphan refid=%"PRIx32, sources[orphan_source]->ref_id);
+    }
+  }
+
+  for (i = 0; i < n_sources; i++) {
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    if (sources[i]->sel_options & SRC_SELECT_TRUST)
+      n_sel_trust_sources++;
+
+    si = &sources[i]->sel_info;
+
+    j1 = n_endpoints;
+    j2 = j1 + 1;
+
+    sort_list[j1].index = i;
+    sort_list[j1].offset = si->lo_limit;
+    sort_list[j1].tag = LOW;
+
+    sort_list[j2].index = i;
+    sort_list[j2].offset = si->hi_limit;
+    sort_list[j2].tag = HIGH;
+
+    n_endpoints += 2;
+  }
+
+  DEBUG_LOG("badstat=%d sel=%d badstat_reach=%o sel_reach=%o size=%d max_reach_ago=%f",
+            n_badstats_sources, n_sel_sources, (unsigned int)max_badstat_reach,
+            (unsigned int)max_sel_reach, max_sel_reach_size, max_reach_sample_ago);
+
+  /* Wait for the next call if we have no source selected and there is
+     a source with bad stats (has less than 3 samples) with reachability
+     equal to shifted maximum reachability of sources with valid stats.
+     This delays selecting source on start with servers using the same
+     polling interval until they all have valid stats. */
+  if (n_badstats_sources && n_sel_sources && selected_source_index == INVALID_SOURCE &&
+      max_sel_reach_size < SOURCE_REACH_BITS && max_sel_reach >> 1 == max_badstat_reach) {
+    mark_ok_sources(SRC_WAITS_STATS);
+    return;
+  }
+
+  if (n_endpoints == 0) {
+    /* No sources provided valid endpoints */
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message(LOGS_INFO, "Can't synchronise: no selectable sources", NULL);
+      selected_source_index = INVALID_SOURCE;
+    }
+    return;
+  }
+
+  /* Now sort the endpoint list */
+  qsort((void *) sort_list, n_endpoints, sizeof(struct Sort_Element), compare_sort_elements);
+
+  /* Now search for the interval which is contained in the most
+     individual source intervals.  Any source which overlaps this
+     will be a candidate.
+
+     If we get a case like
+
+     <----------------------->
+         <-->
+                  <-->
+         <===========>
+
+     we will build the interval as shown with '=', whereas with an extra source we get
+
+     <----------------------->
+        <------->
+         <-->
+                  <-->
+         <==>
+
+     The first case is just bad luck - we need extra sources to
+     detect the falseticker, so just make an arbitrary choice based
+     on stratum & stability etc.
+
+     Intervals from sources specified with the trust option have higher
+     priority in the search.
+     */
+
+  trust_depth = best_trust_depth = 0;
+  depth = best_depth = 0;
+  best_lo = best_hi = best_trust_lo = best_trust_hi = 0.0;
+
+  for (i = 0; i < n_endpoints; i++) {
+    switch (sort_list[i].tag) {
+      case LOW:
+        depth++;
+        if (sources[sort_list[i].index]->sel_options & SRC_SELECT_TRUST)
+          trust_depth++;
+        if (trust_depth > best_trust_depth ||
+            (trust_depth == best_trust_depth && depth > best_depth)) {
+          if (trust_depth > best_trust_depth) {
+            best_trust_depth = trust_depth;
+            best_trust_lo = sort_list[i].offset;
+          }
+          best_depth = depth;
+          best_lo = sort_list[i].offset;
+        }
+        break;
+      case HIGH:
+        if (trust_depth == best_trust_depth) {
+          if (depth == best_depth)
+            best_hi = sort_list[i].offset;
+          best_trust_hi = sort_list[i].offset;
+        }
+        if (sources[sort_list[i].index]->sel_options & SRC_SELECT_TRUST)
+          trust_depth--;
+        depth--;
+        break;
+      default:
+        assert(0);
+    }
+    assert(trust_depth <= depth);
+    assert(trust_depth >= 0);
+  }
+
+  assert(depth == 0 && trust_depth == 0);
+  assert(2 * n_sel_sources == n_endpoints);
+
+  if ((best_trust_depth == 0 && best_depth <= n_sel_sources / 2) ||
+      (best_trust_depth > 0 && best_trust_depth <= n_sel_trust_sources / 2)) {
+    /* Could not even get half the reachable (trusted) sources to agree */
+
+    if (!reported_no_majority) {
+      log_selection_message(LOGS_WARN, "Can't synchronise: no majority", NULL);
+      reported_no_majority = 1;
+    }
+
+    if (selected_source_index != INVALID_SOURCE) {
+      REF_SetUnsynchronised();
+      selected_source_index = INVALID_SOURCE;
+    }
+
+    /* .. and mark all sources as falsetickers (so they appear thus
+       on the outputs from the command client) */
+    mark_ok_sources(SRC_FALSETICKER);
+
+    return;
+  }
+
+  /* We have our interval, now work out which source are in it,
+     i.e. build list of admissible sources. */
+
+  n_sel_sources = 0;
+
+  for (i = 0; i < n_sources; i++) {
+    /* This should be the same condition to get into the endpoint
+       list */
+    if (sources[i]->status != SRC_OK)
+      continue;
+
+    /* Check if source's interval contains the best interval, or is wholly
+       contained within it.  If there are any trusted sources, other sources
+       are required to be wholly contained within the best interval of the
+       trusted sources to not allow non-trusted sources to move the final
+       offset outside the trusted interval. */
+    if ((sources[i]->sel_info.lo_limit <= best_lo &&
+         sources[i]->sel_info.hi_limit >= best_hi) ||
+        (sources[i]->sel_info.lo_limit >= best_lo &&
+         sources[i]->sel_info.hi_limit <= best_hi)) {
+
+      if (!(best_trust_depth == 0 || (sources[i]->sel_options & SRC_SELECT_TRUST) ||
+            (sources[i]->sel_info.lo_limit >= best_trust_lo &&
+             sources[i]->sel_info.hi_limit <= best_trust_hi))) {
+        mark_source(sources[i], SRC_UNTRUSTED);
+        continue;
+      }
+
+      sel_sources[n_sel_sources++] = i;
+
+      if (sources[i]->sel_options & SRC_SELECT_REQUIRE)
+        sel_req_source = 0;
+    } else {
+      mark_source(sources[i], SRC_FALSETICKER);
+      if (!sources[i]->reported_falseticker) {
+        log_selection_source(LOGS_WARN, "Detected falseticker %s", sources[i]);
+        sources[i]->reported_falseticker = 1;
+      }
+    }
+  }
+
+  if (!n_sel_sources || sel_req_source || n_sel_sources < CNF_GetMinSources()) {
+    if (selected_source_index != INVALID_SOURCE) {
+      log_selection_message(LOGS_INFO, "Can't synchronise: %s selectable sources",
+                            !n_sel_sources ? "no" :
+                            sel_req_source ? "no required source in" : "not enough");
+      selected_source_index = INVALID_SOURCE;
+    }
+    mark_ok_sources(SRC_WAITS_SOURCES);
+    return;
+  }
+
+  /* Enable the selectable sources (and trusted if there are any) to
+     vote on leap seconds */
+  for (i = 0; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    if (best_trust_depth && !(sources[index]->sel_options & SRC_SELECT_TRUST))
+      continue;
+    sources[index]->leap_vote = 1;
+  }
+
+  /* If there are any sources with prefer option, reduce the list again
+     only to the preferred sources */
+  for (i = 0; i < n_sel_sources; i++) {
+    if (sources[sel_sources[i]]->sel_options & SRC_SELECT_PREFER)
+      break;
+  }
+  if (i < n_sel_sources) {
+    for (i = j = 0; i < n_sel_sources; i++) {
+      if (!(sources[sel_sources[i]]->sel_options & SRC_SELECT_PREFER))
+        mark_source(sources[sel_sources[i]], SRC_NONPREFERRED);
+      else
+        sel_sources[j++] = sel_sources[i];
+    }
+    assert(j > 0);
+    n_sel_sources = j;
+    sel_prefer = 1;
+  } else {
+    sel_prefer = 0;
+  }
+
+  /* Find minimum stratum */
+
+  index = sel_sources[0];
+  min_stratum = sources[index]->stratum;
+  for (i = 1; i < n_sel_sources; i++) {
+    index = sel_sources[i];
+    stratum = sources[index]->stratum;
+    if (stratum < min_stratum)
+      min_stratum = stratum;
+  }
+
+  /* Update scores and find the source with maximum score */
+
+  max_score_index = INVALID_SOURCE;
+  max_score = 0.0;
+  sel_src_distance = 0.0;
+
+  if (selected_source_index != INVALID_SOURCE)
+    sel_src_distance = sources[selected_source_index]->sel_info.root_distance +
+      (sources[selected_source_index]->stratum - min_stratum) * stratum_weight;
+
+  for (i = 0; i < n_sources; i++) {
+    /* Reset score for non-selectable sources */
+    if (sources[i]->status != SRC_OK ||
+        (sel_prefer && !(sources[i]->sel_options & SRC_SELECT_PREFER))) {
+      sources[i]->sel_score = 1.0;
+      sources[i]->distant = DISTANT_PENALTY;
+      continue;
+    }
+
+    distance = sources[i]->sel_info.root_distance +
+      (sources[i]->stratum - min_stratum) * stratum_weight;
+    if (sources[i]->type == SRC_NTP)
+      distance += reselect_distance;
+
+    if (selected_source_index != INVALID_SOURCE) {
+      /* Update score, but only for source pairs where one source
+         has a new sample */
+      if (sources[i] == updated_inst ||
+          sources[selected_source_index] == updated_inst) {
+
+        sources[i]->sel_score *= sel_src_distance / distance;
+
+        if (sources[i]->sel_score < 1.0)
+          sources[i]->sel_score = 1.0;
+      }
+    } else {
+      /* When there is no selected source yet, assign scores so that the
+         source with minimum distance will have maximum score.  The scores
+         will be reset when the source is selected later in this function. */
+      sources[i]->sel_score = 1.0 / distance;
+    }
+
+    DEBUG_LOG("%s score=%f dist=%f",
+              source_to_string(sources[i]), sources[i]->sel_score, distance);
+
+    if (max_score < sources[i]->sel_score) {
+      max_score = sources[i]->sel_score;
+      max_score_index = i;
+    }
+  }
+
+  assert(max_score_index != INVALID_SOURCE);
+
+  /* Is the current source still a survivor and no other source has reached
+     the score limit? */
+  if (selected_source_index == INVALID_SOURCE ||
+      sources[selected_source_index]->status != SRC_OK ||
+      (max_score_index != selected_source_index && max_score > SCORE_LIMIT)) {
+
+    /* Before selecting the new synchronisation source wait until the reference
+       can be updated */
+    if (sources[max_score_index]->updates == 0) {
+      selected_source_index = INVALID_SOURCE;
+      mark_ok_sources(SRC_WAITS_UPDATE);
+      return;
+    }
+
+    selected_source_index = max_score_index;
+    log_selection_source(LOGS_INFO, "Selected source %s", sources[selected_source_index]);
+
+    /* New source has been selected, reset all scores */
+    for (i = 0; i < n_sources; i++) {
+      sources[i]->sel_score = 1.0;
+      sources[i]->distant = 0;
+      sources[i]->reported_falseticker = 0;
+    }
+
+    reported_no_majority = 0;
+  }
+
+  mark_source(sources[selected_source_index], SRC_SELECTED);
+
+  /* Don't update reference when the selected source has no new samples */
+
+  if (sources[selected_source_index]->updates == 0) {
+    /* Mark the remaining sources as last combine_sources() call */
+
+    for (i = 0; i < n_sel_sources; i++) {
+      index = sel_sources[i];
+      if (sources[index]->status == SRC_OK)
+        mark_source(sources[index], sources[index]->distant ? SRC_DISTANT : SRC_UNSELECTED);
+    }
+    return;
+  }
+
+  for (i = 0; i < n_sources; i++)
+    sources[i]->updates = 0;
+
+  leap_status = get_leap_status();
+
+  /* Now just use the statistics of the selected source combined with
+     the other selectable sources for trimming the local clock */
+
+  SST_GetTrackingData(sources[selected_source_index]->stats, &ref_time,
+                      &src_offset, &src_offset_sd,
+                      &src_frequency, &src_frequency_sd, &src_skew,
+                      &src_root_delay, &src_root_dispersion);
+
+  combined = combine_sources(n_sel_sources, &ref_time, &src_offset, &src_offset_sd,
+                             &src_frequency, &src_frequency_sd, &src_skew);
+
+  REF_SetReference(sources[selected_source_index]->stratum,
+                   leap_status, combined,
+                   sources[selected_source_index]->ref_id,
+                   sources[selected_source_index]->ip_addr,
+                   &ref_time, src_offset, src_offset_sd,
+                   src_frequency, src_frequency_sd, src_skew,
+                   src_root_delay, src_root_dispersion);
+}
+
+/* ================================================== */
+/* Force reselecting the best source */
+
+void
+SRC_ReselectSource(void)
+{
+  selected_source_index = INVALID_SOURCE;
+  SRC_SelectSource(NULL);
+}
+
+/* ================================================== */
+
+void
+SRC_SetReselectDistance(double distance)
+{
+  if (reselect_distance != distance) {
+    reselect_distance = distance;
+    LOG(LOGS_INFO, "New reselect distance %f", distance);
+  }
+}
+
+/* ================================================== */
+/* This routine is registered as a callback with the local clock
+   module, to be called whenever the local clock changes frequency or
+   is slewed.  It runs through all the existing source statistics, and
+   adjusts them to make them look as though they were sampled under
+   the new regime. */
+
+static void
+slew_sources(struct timespec *raw, struct timespec *cooked, double dfreq,
+             double doffset, LCL_ChangeType change_type, void *anything)
+{
+  int i;
+
+  for (i=0; i<n_sources; i++) {
+    if (change_type == LCL_ChangeUnknownStep) {
+      SST_ResetInstance(sources[i]->stats);
+    } else {
+      SST_SlewSamples(sources[i]->stats, cooked, dfreq, doffset);
+    }
+  }
+
+  if (change_type == LCL_ChangeUnknownStep) {
+    /* Update selection status */
+    SRC_SelectSource(NULL);
+  }
+}
+
+/* ================================================== */
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    SST_AddDispersion(sources[i]->stats, dispersion);
+  }
+}
+
+/* ================================================== */
+
+static int
+get_dumpfile(SRC_Instance inst, char *filename, size_t len)
+{
+  /* Use the IP address, or reference ID with reference clocks */
+  switch (inst->type) {
+    case SRC_NTP:
+      if (!UTI_IsIPReal(inst->ip_addr) ||
+          snprintf(filename, len, "%s", source_to_string(inst)) >= len)
+        return 0;
+      break;
+    case SRC_REFCLOCK:
+      if (snprintf(filename, len, "refid:%08"PRIx32, inst->ref_id) >= len)
+        return 0;
+      break;
+    default:
+      assert(0);
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+save_source(SRC_Instance inst)
+{
+  char filename[64], *dumpdir, *ntp_name;
+  FILE *f;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir)
+    return;
+
+  if (!get_dumpfile(inst, filename, sizeof (filename)))
+    return;
+
+  f = UTI_OpenFile(dumpdir, filename, ".dat", 'w', 0644);
+  if (!f)
+    return;
+
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : ".";
+
+  if (fprintf(f, "%s%s\n%d %o %d %d %d\n",
+              DUMP_IDENTIFIER, ntp_name, inst->authenticated,
+              (unsigned int)inst->reachability, inst->reachability_size,
+              inst->stratum, (int)inst->leap) < 0 ||
+      !SST_SaveToFile(inst->stats, f)) {
+    fclose(f);
+    if (!UTI_RemoveFile(dumpdir, filename, ".dat"))
+      ;
+    return;
+  }
+
+  fclose(f);
+}
+
+/* ================================================== */
+/* This is called to dump out the source measurement registers */
+
+void
+SRC_DumpSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++)
+    save_source(sources[i]);
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 1
+
+static void
+load_source(SRC_Instance inst)
+{
+  char filename[64], line[256], *dumpdir, *ntp_name, *words[MAX_WORDS];
+  int auth, leap, reach_size, stratum;
+  unsigned int reach;
+  FILE *f;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir)
+    return;
+
+  if (!get_dumpfile(inst, filename, sizeof (filename)))
+    return;
+
+  f = UTI_OpenFile(dumpdir, filename, ".dat", 'r', 0);
+  if (!f)
+    return;
+
+  ntp_name = inst->type == SRC_NTP ? NSR_GetName(inst->ip_addr) : NULL;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        (inst->type == SRC_NTP && (!ntp_name || strcmp(words[0], ntp_name) != 0)) ||
+      !fgets(line, sizeof (line), f) ||
+        sscanf(words[0], "%d %o %d %d %d",
+               &auth, &reach, &reach_size, &stratum, &leap) != 5 ||
+        (!auth && inst->authenticated) ||
+        stratum < 0 || stratum >= NTP_MAX_STRATUM ||
+        leap < LEAP_Normal || leap >= LEAP_Unsynchronised ||
+      !SST_LoadFromFile(inst->stats, f)) {
+    LOG(LOGS_WARN, "Could not load dump file for %s", source_to_string(inst));
+    fclose(f);
+    return;
+  }
+
+  inst->reachability = reach & ((1U << SOURCE_REACH_BITS) - 1);
+  inst->reachability_size = CLAMP(0, reach_size, SOURCE_REACH_BITS);
+  inst->stratum = stratum;
+  inst->leap = leap;
+
+  LOG(LOGS_INFO, "Loaded dump file for %s", source_to_string(inst));
+
+  fclose(f);
+}
+
+/* ================================================== */
+
+void
+SRC_ReloadSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    load_source(sources[i]);
+
+    /* Allow an immediate update of the reference */
+    sources[i]->updates++;
+  }
+
+  /* Select sources and set the reference */
+  SRC_SelectSource(NULL);
+}
+
+/* ================================================== */
+
+void
+SRC_RemoveDumpFiles(void)
+{
+  char pattern[PATH_MAX], name[64], *dumpdir, *s;
+  IPAddr ip_addr;
+  glob_t gl;
+  size_t i;
+
+  dumpdir = CNF_GetDumpDir();
+  if (!dumpdir ||
+      snprintf(pattern, sizeof (pattern), "%s/*.dat", dumpdir) >= sizeof (pattern))
+    return;
+
+  if (glob(pattern, 0, NULL, &gl))
+    return;
+
+  for (i = 0; i < gl.gl_pathc; i++) {
+    s = strrchr(gl.gl_pathv[i], '/');
+    if (!s || snprintf(name, sizeof (name), "%s", s + 1) >= sizeof (name))
+      continue;
+
+    /* Remove .dat extension */
+    if (strlen(name) < 4)
+      continue;
+    name[strlen(name) - 4] = '\0';
+
+    /* Check if it looks like name of an actual dump file */
+    if (strncmp(name, "refid:", 6) && !UTI_StringToIP(name, &ip_addr))
+      continue;
+
+    if (!UTI_RemoveFile(NULL, gl.gl_pathv[i], NULL))
+      ;
+  }
+
+  globfree(&gl);
+}
+
+/* ================================================== */
+
+void
+SRC_ResetSources(void)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++)
+    SRC_ResetInstance(sources[i]);
+
+  LOG(LOGS_INFO, "Reset all sources");
+}
+
+/* ================================================== */
+
+int
+SRC_IsSyncPeer(SRC_Instance inst)
+{
+  if (inst->index == selected_source_index) {
+    return 1;
+  } else {
+    return 0;
+  }
+
+}
+
+/* ================================================== */
+
+int
+SRC_IsReachable(SRC_Instance inst)
+{
+  return inst->reachability != 0;
+}
+
+/* ================================================== */
+
+int
+SRC_ReadNumberOfSources(void)
+{
+  return n_sources;
+}
+
+/* ================================================== */
+
+int
+SRC_ActiveSources(void)
+{
+  int i, r;
+
+  for (i = r = 0; i < n_sources; i++)
+    if (sources[i]->active)
+      r++;
+
+  return r;
+}
+
+/* ================================================== */
+
+static SRC_Instance
+find_source(IPAddr *ip, uint32_t ref_id)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    if ((ip->family != IPADDR_UNSPEC && sources[i]->type == SRC_NTP &&
+         UTI_CompareIPs(ip, sources[i]->ip_addr, NULL) == 0) ||
+        (ip->family == IPADDR_UNSPEC && sources[i]->type == SRC_REFCLOCK &&
+         ref_id == sources[i]->ref_id))
+      return sources[i];
+  }
+
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+SRC_ModifySelectOptions(IPAddr *ip, uint32_t ref_id, int options, int mask)
+{
+  SRC_Instance inst;
+
+  inst = find_source(ip, ref_id);
+  if (!inst)
+    return 0;
+
+  if ((inst->conf_sel_options & mask) == options)
+    return 1;
+
+  inst->conf_sel_options = (inst->conf_sel_options & ~mask) | options;
+  LOG(LOGS_INFO, "Source %s selection options modified", source_to_string(inst));
+
+  update_sel_options();
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SRC_ReportSource(int index, RPT_SourceReport *report, struct timespec *now)
+{
+  SRC_Instance src;
+  if ((index >= n_sources) || (index < 0)) {
+    return 0;
+  } else {
+    src = sources[index];
+
+    if (src->ip_addr)
+      report->ip_addr = *src->ip_addr;
+    else {
+      /* Use refid as an address */
+      report->ip_addr.addr.in4 = src->ref_id;
+      report->ip_addr.family = IPADDR_INET4;
+    }
+
+    report->stratum = src->stratum;
+
+    switch (src->status) {
+      case SRC_FALSETICKER:
+        report->state = RPT_FALSETICKER;
+        break;
+      case SRC_JITTERY:
+        report->state = RPT_JITTERY;
+        break;
+      case SRC_WAITS_SOURCES:
+      case SRC_NONPREFERRED:
+      case SRC_WAITS_UPDATE:
+      case SRC_DISTANT:
+      case SRC_OUTLIER:
+        report->state = RPT_SELECTABLE;
+        break;
+      case SRC_UNSELECTED:
+        report->state = RPT_UNSELECTED;
+        break;
+      case SRC_SELECTED:
+        report->state = RPT_SELECTED;
+        break;
+      default:
+        report->state = RPT_NONSELECTABLE;
+        break;
+    }
+
+    report->reachability = src->reachability;
+
+    /* Call stats module to fill out estimates */
+    SST_DoSourceReport(src->stats, report, now);
+
+    return 1;
+  }
+
+}
+
+/* ================================================== */
+
+int
+SRC_ReportSourcestats(int index, RPT_SourcestatsReport *report, struct timespec *now)
+{ 
+  SRC_Instance src;
+
+  if ((index >= n_sources) || (index < 0)) {
+    return 0;
+  } else {
+    src = sources[index];
+    report->ref_id = src->ref_id;
+    if (src->ip_addr)
+      report->ip_addr = *src->ip_addr;
+    else
+      report->ip_addr.family = IPADDR_UNSPEC; 
+    SST_DoSourcestatsReport(src->stats, report, now);
+    return 1;
+  }
+}
+
+/* ================================================== */
+
+static char
+get_status_char(SRC_Status status)
+{
+  switch (status) {
+    case SRC_UNSELECTABLE:
+      return 'N';
+    case SRC_UNSYNCHRONISED:
+      return 's';
+    case SRC_BAD_STATS:
+      return 'M';
+    case SRC_BAD_DISTANCE:
+      return 'd';
+    case SRC_JITTERY:
+      return '~';
+    case SRC_WAITS_STATS:
+      return 'w';
+    case SRC_STALE:
+      return 'S';
+    case SRC_ORPHAN:
+      return 'O';
+    case SRC_UNTRUSTED:
+      return 'T';
+    case SRC_FALSETICKER:
+      return 'x';
+    case SRC_WAITS_SOURCES:
+      return 'W';
+    case SRC_NONPREFERRED:
+      return 'P';
+    case SRC_WAITS_UPDATE:
+      return 'U';
+    case SRC_DISTANT:
+      return 'D';
+    case SRC_OUTLIER:
+      return 'L';
+    case SRC_UNSELECTED:
+      return '+';
+    case SRC_SELECTED:
+      return '*';
+    default:
+      return '?';
+  }
+}
+
+/* ================================================== */
+
+int
+SRC_GetSelectReport(int index, RPT_SelectReport *report)
+{
+  SRC_Instance inst;
+
+  if (index >= n_sources || index < 0)
+    return 0;
+
+  inst = sources[index];
+
+  report->ref_id = inst->ref_id;
+  if (inst->ip_addr)
+    report->ip_addr = *inst->ip_addr;
+  else
+    report->ip_addr.family = IPADDR_UNSPEC;
+  report->state_char = get_status_char(inst->status);
+  report->authentication = inst->authenticated;
+  report->leap = inst->leap;
+  report->conf_options = inst->conf_sel_options;
+  report->eff_options = inst->sel_options;
+  report->last_sample_ago = inst->sel_info.last_sample_ago;
+  report->score = inst->sel_score;
+  report->lo_limit = inst->sel_info.lo_limit;
+  report->hi_limit = inst->sel_info.hi_limit;
+
+  return 1;
+}
+
+/* ================================================== */
+
+SRC_Type
+SRC_GetType(int index)
+{
+  if ((index >= n_sources) || (index < 0))
+    return -1;
+  return sources[index]->type;
+}
+
+/* ================================================== */
diff --git a/sources.h b/sources.h
new file mode 100644
index 0000000..da3a533
--- /dev/null
+++ b/sources.h
@@ -0,0 +1,144 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header for the module that manages the collection of all
+  sources that we are making measurements from.  This include all NTP
+  servers & peers, locally connected reference sources, eye/wristwatch
+  drivers etc */
+
+#ifndef GOT_SOURCES_H
+#define GOT_SOURCES_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+#include "reports.h"
+#include "sourcestats.h"
+
+/* Size of the source reachability register */
+#define SOURCE_REACH_BITS 8
+
+/* This datatype is used to hold information about sources.  The
+   instance must be passed when calling many of the interface
+   functions */
+
+typedef struct SRC_Instance_Record *SRC_Instance;
+
+/* Initialisation function */
+extern void SRC_Initialise(void);
+
+/* Finalisation function */
+extern void SRC_Finalise(void);
+
+/* Modes for selecting NTP sources based on their authentication status */
+typedef enum {
+  SRC_AUTHSELECT_IGNORE,
+  SRC_AUTHSELECT_MIX,
+  SRC_AUTHSELECT_PREFER,
+  SRC_AUTHSELECT_REQUIRE,
+} SRC_AuthSelectMode;
+
+typedef enum {
+  SRC_NTP,                      /* NTP client/peer */
+  SRC_REFCLOCK                  /* Rerefence clock */
+} SRC_Type;
+
+/* Function to create a new instance.  This would be called by one of
+   the individual source-type instance creation routines. */
+
+extern SRC_Instance SRC_CreateNewInstance(uint32_t ref_id, SRC_Type type, int authenticated,
+                                          int sel_options, IPAddr *addr, int min_samples,
+                                          int max_samples, double min_delay, double asymmetry);
+
+/* Function to get rid of a source when it is being unconfigured.
+   This may cause the current reference source to be reselected, if this
+   was the reference source or contributed significantly to a
+   falseticker decision. */
+
+extern void SRC_DestroyInstance(SRC_Instance instance);
+
+/* Function to reset a source */
+extern void SRC_ResetInstance(SRC_Instance instance);
+
+/* Function to change the sources's reference ID and IP address */
+extern void SRC_SetRefid(SRC_Instance instance, uint32_t ref_id, IPAddr *addr);
+
+/* Function to get access to the sourcestats instance */
+extern SST_Stats SRC_GetSourcestats(SRC_Instance instance);
+
+/* Function to update the stratum and leap status of the source */
+extern void SRC_UpdateStatus(SRC_Instance instance, int stratum, NTP_Leap leap);
+
+/* Function to accumulate a new sample from the source */
+extern void SRC_AccumulateSample(SRC_Instance instance, NTP_Sample *sample);
+
+/* This routine sets the source as receiving reachability updates */
+extern void SRC_SetActive(SRC_Instance inst);
+
+/* This routine sets the source as not receiving reachability updates */
+extern void SRC_UnsetActive(SRC_Instance inst);
+
+/* This routine updates the reachability register */
+extern void SRC_UpdateReachability(SRC_Instance inst, int reachable);
+
+/* This routine marks the source unreachable */
+extern void SRC_ResetReachability(SRC_Instance inst);
+
+/* This routine is used to select the best source from amongst those
+   we currently have valid data on, and use it as the tracking base
+   for the local time.  Updates are made to the local reference only
+   when the selected source was updated (set as updated_inst) since
+   the last reference update.  This avoids updating the frequency
+   tracking for every sample from other sources - only the ones from
+   the selected reference make a difference. */
+extern void SRC_SelectSource(SRC_Instance updated_inst);
+
+/* Force reselecting the best source */
+extern void SRC_ReselectSource(void);
+
+/* Set reselect distance */
+extern void SRC_SetReselectDistance(double distance);
+
+extern void SRC_DumpSources(void);
+extern void SRC_ReloadSources(void);
+extern void SRC_RemoveDumpFiles(void);
+
+extern void SRC_ResetSources(void);
+
+extern int SRC_IsSyncPeer(SRC_Instance inst);
+extern int SRC_IsReachable(SRC_Instance inst);
+extern int SRC_ReadNumberOfSources(void);
+extern int SRC_ActiveSources(void);
+
+/* Modify selection options of an NTP source specified by address, or
+   refclock specified by its reference ID */
+extern int SRC_ModifySelectOptions(IPAddr *ip, uint32_t ref_id, int options, int mask);
+
+extern int SRC_ReportSource(int index, RPT_SourceReport *report, struct timespec *now);
+extern int SRC_ReportSourcestats(int index, RPT_SourcestatsReport *report, struct timespec *now);
+extern int SRC_GetSelectReport(int index, RPT_SelectReport *report);
+
+extern SRC_Type SRC_GetType(int index);
+
+#endif /* GOT_SOURCES_H */
diff --git a/sourcestats.c b/sourcestats.c
new file mode 100644
index 0000000..ce326e9
--- /dev/null
+++ b/sourcestats.c
@@ -0,0 +1,1041 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2011-2014, 2016-2018, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains the routines that do the statistical
+  analysis on the samples obtained from the sources,
+  to determined frequencies and error bounds. */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sourcestats.h"
+#include "memory.h"
+#include "regress.h"
+#include "util.h"
+#include "conf.h"
+#include "logging.h"
+#include "local.h"
+
+/* ================================================== */
+/* Define the maxumum number of samples that we want
+   to store per source */
+#define MAX_SAMPLES 64
+
+/* This is the assumed worst case bound on an unknown frequency,
+   2000ppm, which would be pretty bad */
+#define WORST_CASE_FREQ_BOUND (2000.0/1.0e6)
+
+/* The minimum and maximum assumed skew */
+#define MIN_SKEW 1.0e-12
+#define MAX_SKEW 1.0e+02
+
+/* The minimum standard deviation */
+#define MIN_STDDEV 1.0e-9
+
+/* The worst case bound on an unknown standard deviation of the offset */
+#define WORST_CASE_STDDEV_BOUND 4.0
+
+/* The asymmetry of network jitter when all jitter is in one direction */
+#define MAX_ASYMMETRY 0.5
+
+/* The minimum estimated asymmetry that can activate the offset correction */
+#define MIN_ASYMMETRY 0.45
+
+/* The minimum number of consecutive asymmetries with the same sign needed
+   to activate the offset correction */
+#define MIN_ASYMMETRY_RUN 10
+
+/* The maximum value of the counter */
+#define MAX_ASYMMETRY_RUN 1000
+
+/* ================================================== */
+
+static LOG_FileID logfileid;
+
+/* ================================================== */
+/* This data structure is used to hold the history of data from the
+   source */
+
+struct SST_Stats_Record {
+
+  /* Reference ID and IP address (NULL if not an NTP source) */
+  uint32_t refid;
+  IPAddr *ip_addr;
+
+  /* User defined minimum and maximum number of samples */
+  int min_samples;
+  int max_samples;
+
+  /* User defined minimum delay */
+  double fixed_min_delay;
+
+  /* User defined asymmetry of network jitter */
+  double fixed_asymmetry;
+
+  /* Number of samples currently stored.  The samples are stored in circular
+     buffer. */
+  int n_samples;
+
+  /* Number of extra samples stored in sample_times, offsets and peer_delays
+     arrays that are used to extend the runs test */
+  int runs_samples;
+
+  /* The index of the newest sample */
+  int last_sample;
+
+  /* Flag indicating whether last regression was successful */
+  int regression_ok;
+
+  /* The best individual sample that we are holding, in terms of the minimum
+     root distance at the present time */
+  int best_single_sample;
+
+  /* The index of the sample with minimum delay in peer_delays */
+  int min_delay_sample;
+
+  /* This is the estimated offset (+ve => local fast) at a particular time */
+  double estimated_offset;
+  double estimated_offset_sd;
+  struct timespec offset_time;
+
+  /* Number of runs of the same sign amongst the residuals */
+  int nruns;
+
+  /* Number of consecutive estimated asymmetries with the same sign.
+     The sign of the number encodes the sign of the asymmetry. */
+  int asymmetry_run;
+
+  /* This is the latest estimated asymmetry of network jitter */
+  double asymmetry;
+
+  /* This value contains the estimated frequency.  This is the number
+     of seconds that the local clock gains relative to the reference
+     source per unit local time.  (Positive => local clock fast,
+     negative => local clock slow) */
+  double estimated_frequency;
+  double estimated_frequency_sd;
+
+  /* This is the assumed worst case bounds on the estimated frequency.
+     We assume that the true frequency lies within +/- half this much
+     about estimated_frequency */
+  double skew;
+
+  /* This is the estimated standard deviation of the data points */
+  double std_dev;
+
+  /* This array contains the sample epochs, in terms of the local
+     clock. */
+  struct timespec sample_times[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of offsets, in seconds, corresponding to the
+     sample times.  In this module, we use the convention that
+     positive means the local clock is FAST of the source and negative
+     means it is SLOW.  This is contrary to the convention in the NTP
+     stuff. */
+  double offsets[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of the offsets as originally measured.  Local
+     clock fast of real time is indicated by positive values.  This
+     array is not slewed to adjust the readings when we apply
+     adjustments to the local clock, as is done for the array
+     'offset'. */
+  double orig_offsets[MAX_SAMPLES];
+
+  /* This is an array of peer delays, in seconds, being the roundtrip
+     measurement delay to the peer */
+  double peer_delays[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+
+  /* This is an array of peer dispersions, being the skew and local
+     precision dispersion terms from sampling the peer */
+  double peer_dispersions[MAX_SAMPLES];
+
+  /* This array contains the root delays of each sample, in seconds */
+  double root_delays[MAX_SAMPLES];
+
+  /* This array contains the root dispersions of each sample at the
+     time of the measurements */
+  double root_dispersions[MAX_SAMPLES];
+};
+
+/* ================================================== */
+
+static void find_min_delay_sample(SST_Stats inst);
+static int get_buf_index(SST_Stats inst, int i);
+
+/* ================================================== */
+
+void
+SST_Initialise(void)
+{
+  logfileid = CNF_GetLogStatistics() ? LOG_FileOpen("statistics",
+      "   Date (UTC) Time     IP Address    Std dev'n Est offset  Offset sd  Diff freq   Est skew  Stress  Ns  Bs  Nr  Asym")
+    : -1;
+}
+
+/* ================================================== */
+
+void
+SST_Finalise(void)
+{
+}
+
+/* ================================================== */
+/* This function creates a new instance of the statistics handler */
+
+SST_Stats
+SST_CreateInstance(uint32_t refid, IPAddr *addr, int min_samples, int max_samples,
+                   double min_delay, double asymmetry)
+{
+  SST_Stats inst;
+  inst = MallocNew(struct SST_Stats_Record);
+
+  inst->max_samples = max_samples > 0 ? CLAMP(1, max_samples, MAX_SAMPLES) : MAX_SAMPLES;
+  inst->min_samples = CLAMP(1, min_samples, inst->max_samples);
+  inst->fixed_min_delay = min_delay;
+  inst->fixed_asymmetry = asymmetry;
+
+  SST_SetRefid(inst, refid, addr);
+  SST_ResetInstance(inst);
+
+  return inst;
+}
+
+/* ================================================== */
+/* This function deletes an instance of the statistics handler. */
+
+void
+SST_DeleteInstance(SST_Stats inst)
+{
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+SST_ResetInstance(SST_Stats inst)
+{
+  inst->n_samples = 0;
+  inst->runs_samples = 0;
+  inst->last_sample = 0;
+  inst->regression_ok = 0;
+  inst->best_single_sample = 0;
+  inst->min_delay_sample = 0;
+  inst->estimated_frequency = 0;
+  inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
+  inst->skew = WORST_CASE_FREQ_BOUND;
+  inst->estimated_offset = 0.0;
+  inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
+  UTI_ZeroTimespec(&inst->offset_time);
+  inst->std_dev = WORST_CASE_STDDEV_BOUND;
+  inst->nruns = 0;
+  inst->asymmetry_run = 0;
+  inst->asymmetry = 0.0;
+}
+
+/* ================================================== */
+
+void
+SST_SetRefid(SST_Stats inst, uint32_t refid, IPAddr *addr)
+{
+  inst->refid = refid;
+  inst->ip_addr = addr;
+}
+
+/* ================================================== */
+/* This function is called to prune the register down when it is full.
+   For now, just discard the oldest sample.  */
+
+static void
+prune_register(SST_Stats inst, int new_oldest)
+{
+  if (!new_oldest)
+    return;
+
+  assert(inst->n_samples >= new_oldest);
+  inst->n_samples -= new_oldest;
+  inst->runs_samples += new_oldest;
+  if (inst->runs_samples > inst->n_samples * (REGRESS_RUNS_RATIO - 1))
+    inst->runs_samples = inst->n_samples * (REGRESS_RUNS_RATIO - 1);
+  
+  assert(inst->n_samples + inst->runs_samples <= MAX_SAMPLES * REGRESS_RUNS_RATIO);
+
+  find_min_delay_sample(inst);
+}
+
+/* ================================================== */
+
+void
+SST_AccumulateSample(SST_Stats inst, NTP_Sample *sample)
+{
+  int n, m;
+
+  /* Make room for the new sample */
+  if (inst->n_samples > 0 &&
+      (inst->n_samples == MAX_SAMPLES || inst->n_samples == inst->max_samples)) {
+    prune_register(inst, 1);
+  }
+
+  /* Make sure it's newer than the last sample */
+  if (inst->n_samples &&
+      UTI_CompareTimespecs(&inst->sample_times[inst->last_sample], &sample->time) >= 0) {
+    LOG(LOGS_WARN, "Out of order sample detected, discarding history for %s",
+        inst->ip_addr ? UTI_IPToString(inst->ip_addr) : UTI_RefidToString(inst->refid));
+    SST_ResetInstance(inst);
+  }
+
+  n = inst->last_sample = (inst->last_sample + 1) %
+    (MAX_SAMPLES * REGRESS_RUNS_RATIO);
+  m = n % MAX_SAMPLES;
+
+  /* WE HAVE TO NEGATE OFFSET IN THIS CALL, IT IS HERE THAT THE SENSE OF OFFSET
+     IS FLIPPED */
+  inst->sample_times[n] = sample->time;
+  inst->offsets[n] = -sample->offset;
+  inst->orig_offsets[m] = -sample->offset;
+  inst->peer_delays[n] = sample->peer_delay;
+  inst->peer_dispersions[m] = sample->peer_dispersion;
+  inst->root_delays[m] = sample->root_delay;
+  inst->root_dispersions[m] = sample->root_dispersion;
+ 
+  if (inst->peer_delays[n] < inst->fixed_min_delay)
+    inst->peer_delays[n] = 2.0 * inst->fixed_min_delay - inst->peer_delays[n];
+
+  if (!inst->n_samples || inst->peer_delays[n] < inst->peer_delays[inst->min_delay_sample])
+    inst->min_delay_sample = n;
+
+  ++inst->n_samples;
+}
+
+/* ================================================== */
+/* Return index of the i-th sample in the sample_times and offset buffers,
+   i can be negative down to -runs_samples */
+
+static int
+get_runsbuf_index(SST_Stats inst, int i)
+{
+  return (unsigned int)(inst->last_sample + 2 * MAX_SAMPLES * REGRESS_RUNS_RATIO -
+      inst->n_samples + i + 1) % (MAX_SAMPLES * REGRESS_RUNS_RATIO);
+}
+
+/* ================================================== */
+/* Return index of the i-th sample in the other buffers */
+
+static int
+get_buf_index(SST_Stats inst, int i)
+{
+  return (unsigned int)(inst->last_sample + MAX_SAMPLES * REGRESS_RUNS_RATIO -
+      inst->n_samples + i + 1) % MAX_SAMPLES;
+}
+
+/* ================================================== */
+/* This function is used by both the regression routines to find the
+   time interval between each historical sample and the most recent
+   one */
+
+static void
+convert_to_intervals(SST_Stats inst, double *times_back)
+{
+  struct timespec *ts;
+  int i;
+
+  ts = &inst->sample_times[inst->last_sample];
+  for (i = -inst->runs_samples; i < inst->n_samples; i++) {
+    /* The entries in times_back[] should end up negative */
+    times_back[i] = UTI_DiffTimespecsToDouble(&inst->sample_times[get_runsbuf_index(inst, i)], ts);
+  }
+}
+
+/* ================================================== */
+
+static void
+find_best_sample_index(SST_Stats inst, double *times_back)
+{
+  /* With the value of skew that has been computed, see which of the
+     samples offers the tightest bound on root distance */
+
+  double root_distance, best_root_distance;
+  double elapsed;
+  int i, j, best_index;
+
+  if (!inst->n_samples)
+    return;
+
+  best_index = -1;
+  best_root_distance = DBL_MAX;
+
+  for (i = 0; i < inst->n_samples; i++) {
+    j = get_buf_index(inst, i);
+
+    elapsed = -times_back[i];
+    assert(elapsed >= 0.0);
+
+    root_distance = inst->root_dispersions[j] + elapsed * inst->skew + 0.5 * inst->root_delays[j];
+    if (root_distance < best_root_distance) {
+      best_root_distance = root_distance;
+      best_index = i;
+    }
+  }
+
+  assert(best_index >= 0);
+  inst->best_single_sample = best_index;
+}
+
+/* ================================================== */
+
+static void
+find_min_delay_sample(SST_Stats inst)
+{
+  int i, index;
+
+  inst->min_delay_sample = get_runsbuf_index(inst, -inst->runs_samples);
+
+  for (i = -inst->runs_samples + 1; i < inst->n_samples; i++) {
+    index = get_runsbuf_index(inst, i);
+    if (inst->peer_delays[index] < inst->peer_delays[inst->min_delay_sample])
+      inst->min_delay_sample = index;
+  }
+}
+
+/* ================================================== */
+/* This function estimates asymmetry of network jitter on the path to the
+   source as a slope of offset against network delay in multiple linear
+   regression.  If the asymmetry is significant and its sign doesn't change
+   frequently, the measured offsets (which are used later to estimate the
+   offset and frequency of the clock) are corrected to correspond to the
+   minimum network delay.  This can significantly improve the accuracy and
+   stability of the estimated offset and frequency. */
+
+static int
+estimate_asymmetry(double *times_back, double *offsets, double *delays, int n,
+                   double *asymmetry, int *asymmetry_run)
+{
+  double a;
+
+  /* Reset the counter when the regression fails or the sign changes */
+  if (!RGR_MultipleRegress(times_back, delays, offsets, n, &a) ||
+      a * *asymmetry_run < 0.0) {
+    *asymmetry = 0;
+    *asymmetry_run = 0.0;
+    return 0;
+  }
+
+  if (a <= -MIN_ASYMMETRY && *asymmetry_run > -MAX_ASYMMETRY_RUN)
+    (*asymmetry_run)--;
+  else if (a >= MIN_ASYMMETRY && *asymmetry_run < MAX_ASYMMETRY_RUN)
+    (*asymmetry_run)++;
+
+  if (abs(*asymmetry_run) < MIN_ASYMMETRY_RUN)
+    return 0;
+
+  *asymmetry = CLAMP(-MAX_ASYMMETRY, a, MAX_ASYMMETRY);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+correct_asymmetry(SST_Stats inst, double *times_back, double *offsets)
+{
+  double min_delay, delays[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  int i, n;
+
+  /* Check if the asymmetry was not specified to be zero */
+  if (inst->fixed_asymmetry == 0.0)
+    return;
+
+  min_delay = SST_MinRoundTripDelay(inst);
+  n = inst->runs_samples + inst->n_samples;
+
+  for (i = 0; i < n; i++)
+    delays[i] = inst->peer_delays[get_runsbuf_index(inst, i - inst->runs_samples)] -
+                min_delay;
+
+  if (fabs(inst->fixed_asymmetry) <= MAX_ASYMMETRY) {
+    inst->asymmetry = inst->fixed_asymmetry;
+  } else {
+    if (!estimate_asymmetry(times_back, offsets, delays, n,
+                            &inst->asymmetry, &inst->asymmetry_run))
+      return;
+  }
+
+  /* Correct the offsets */
+  for (i = 0; i < n; i++)
+    offsets[i] -= inst->asymmetry * delays[i];
+}
+
+/* ================================================== */
+
+/* This defines the assumed ratio between the standard deviation of
+   the samples and the peer distance as measured from the round trip
+   time.  E.g. a value of 4 means that we think the standard deviation
+   is four times the fluctuation  of the peer distance */
+
+#define SD_TO_DIST_RATIO 0.7
+
+/* ================================================== */
+/* This function runs the linear regression operation on the data.  It
+   finds the set of most recent samples that give the tightest
+   confidence interval for the frequency, and truncates the register
+   down to that number of samples */
+
+void
+SST_DoNewRegression(SST_Stats inst)
+{
+  double times_back[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  double offsets[MAX_SAMPLES * REGRESS_RUNS_RATIO];
+  double peer_distances[MAX_SAMPLES];
+  double weights[MAX_SAMPLES];
+
+  int degrees_of_freedom;
+  int best_start, times_back_start;
+  double est_intercept, est_slope, est_var, est_intercept_sd, est_slope_sd;
+  int i, j, nruns;
+  double min_distance, median_distance;
+  double sd_weight, sd;
+  double old_skew, old_freq, stress;
+  double precision;
+
+  convert_to_intervals(inst, times_back + inst->runs_samples);
+
+  if (inst->n_samples > 0) {
+    for (i = -inst->runs_samples; i < inst->n_samples; i++) {
+      offsets[i + inst->runs_samples] = inst->offsets[get_runsbuf_index(inst, i)];
+    }
+  
+    for (i = 0, min_distance = DBL_MAX; i < inst->n_samples; i++) {
+      j = get_buf_index(inst, i);
+      peer_distances[i] = 0.5 * inst->peer_delays[get_runsbuf_index(inst, i)] +
+                          inst->peer_dispersions[j];
+      if (peer_distances[i] < min_distance) {
+        min_distance = peer_distances[i];
+      }
+    }
+
+    /* And now, work out the weight vector */
+
+    precision = LCL_GetSysPrecisionAsQuantum();
+    median_distance = RGR_FindMedian(peer_distances, inst->n_samples);
+
+    sd = (median_distance - min_distance) / SD_TO_DIST_RATIO;
+    sd = CLAMP(precision, sd, min_distance);
+    min_distance += precision;
+
+    for (i=0; i<inst->n_samples; i++) {
+      sd_weight = 1.0;
+      if (peer_distances[i] > min_distance)
+        sd_weight += (peer_distances[i] - min_distance) / sd;
+      weights[i] = SQUARE(sd_weight);
+    }
+  }
+
+  correct_asymmetry(inst, times_back, offsets);
+
+  inst->regression_ok = RGR_FindBestRegression(times_back + inst->runs_samples,
+                                         offsets + inst->runs_samples, weights,
+                                         inst->n_samples, inst->runs_samples,
+                                         inst->min_samples,
+                                         &est_intercept, &est_slope, &est_var,
+                                         &est_intercept_sd, &est_slope_sd,
+                                         &best_start, &nruns, &degrees_of_freedom);
+
+  if (inst->regression_ok) {
+
+    old_skew = inst->skew;
+    old_freq = inst->estimated_frequency;
+  
+    inst->estimated_frequency = est_slope;
+    inst->estimated_frequency_sd = CLAMP(MIN_SKEW, est_slope_sd, MAX_SKEW);
+    inst->skew = est_slope_sd * RGR_GetTCoef(degrees_of_freedom);
+    inst->estimated_offset = est_intercept;
+    inst->offset_time = inst->sample_times[inst->last_sample];
+    inst->estimated_offset_sd = est_intercept_sd;
+    inst->std_dev = MAX(MIN_STDDEV, sqrt(est_var));
+    inst->nruns = nruns;
+
+    inst->skew = CLAMP(MIN_SKEW, inst->skew, MAX_SKEW);
+    stress = fabs(old_freq - inst->estimated_frequency) / old_skew;
+
+    DEBUG_LOG("off=%e freq=%e skew=%e n=%d bs=%d runs=%d asym=%f arun=%d",
+              inst->estimated_offset, inst->estimated_frequency, inst->skew,
+              inst->n_samples, best_start, inst->nruns,
+              inst->asymmetry, inst->asymmetry_run);
+
+    if (logfileid != -1) {
+      LOG_FileWrite(logfileid, "%s %-15s %10.3e %10.3e %10.3e %10.3e %10.3e %7.1e %3d %3d %3d %5.2f",
+              UTI_TimeToLogForm(inst->offset_time.tv_sec),
+              inst->ip_addr ? UTI_IPToString(inst->ip_addr) : UTI_RefidToString(inst->refid),
+              inst->std_dev,
+              inst->estimated_offset, inst->estimated_offset_sd,
+              inst->estimated_frequency, inst->skew, stress,
+              inst->n_samples, best_start, inst->nruns,
+              inst->asymmetry);
+    }
+
+    times_back_start = inst->runs_samples + best_start;
+    prune_register(inst, best_start);
+  } else {
+    inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
+    inst->skew = WORST_CASE_FREQ_BOUND;
+    inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
+    inst->std_dev = WORST_CASE_STDDEV_BOUND;
+    inst->nruns = 0;
+
+    if (inst->n_samples > 0) {
+      inst->estimated_offset = inst->offsets[inst->last_sample];
+      inst->offset_time = inst->sample_times[inst->last_sample];
+    } else {
+      inst->estimated_offset = 0.0;
+      UTI_ZeroTimespec(&inst->offset_time);
+    }
+
+    times_back_start = 0;
+  }
+
+  find_best_sample_index(inst, times_back + times_back_start);
+
+}
+
+/* ================================================== */
+/* Return the assumed worst case range of values that this source's
+   frequency lies within.  Frequency is defined as the amount of time
+   the local clock gains relative to the source per unit local clock
+   time. */
+void
+SST_GetFrequencyRange(SST_Stats inst,
+                      double *lo, double *hi)
+{
+  double freq, skew;
+  freq = inst->estimated_frequency;
+  skew = inst->skew;
+  *lo = freq - skew;
+  *hi = freq + skew;
+
+  /* This function is currently used only to determine the values of delta
+     and epsilon in the ntp_core module. Limit the skew to a reasonable maximum
+     to avoid failing the dispersion test too easily. */
+  if (skew > WORST_CASE_FREQ_BOUND) {
+    *lo = -WORST_CASE_FREQ_BOUND;
+    *hi = WORST_CASE_FREQ_BOUND;
+  }
+}
+
+/* ================================================== */
+
+void
+SST_GetSelectionData(SST_Stats inst, struct timespec *now,
+                     double *offset_lo_limit,
+                     double *offset_hi_limit,
+                     double *root_distance,
+                     double *std_dev,
+                     double *first_sample_ago,
+                     double *last_sample_ago,
+                     int *select_ok)
+{
+  double offset, sample_elapsed;
+  int i, j;
+  
+  if (!inst->n_samples) {
+    *select_ok = 0;
+    return;
+  }
+
+  i = get_runsbuf_index(inst, inst->best_single_sample);
+  j = get_buf_index(inst, inst->best_single_sample);
+
+  *std_dev = inst->std_dev;
+
+  sample_elapsed = fabs(UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]));
+  offset = inst->offsets[i] + sample_elapsed * inst->estimated_frequency;
+  *root_distance = 0.5 * inst->root_delays[j] +
+    inst->root_dispersions[j] + sample_elapsed * inst->skew;
+
+  *offset_lo_limit = offset - *root_distance;
+  *offset_hi_limit = offset + *root_distance;
+
+#if 0
+  double average_offset, elapsed;
+  int average_ok;
+  /* average_ok ignored for now */
+  elapsed = UTI_DiffTimespecsToDouble(now, &inst->offset_time);
+  average_offset = inst->estimated_offset + inst->estimated_frequency * elapsed;
+  if (fabs(average_offset - offset) <=
+      inst->peer_dispersions[j] + 0.5 * inst->peer_delays[i]) {
+    average_ok = 1;
+  } else {
+    average_ok = 0;
+  }
+#endif
+
+  i = get_runsbuf_index(inst, 0);
+  *first_sample_ago = UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]);
+  i = get_runsbuf_index(inst, inst->n_samples - 1);
+  *last_sample_ago = UTI_DiffTimespecsToDouble(now, &inst->sample_times[i]);
+
+  *select_ok = inst->regression_ok;
+
+  /* If maxsamples is too small to have a successful regression, enable the
+     selection as a special case for a fast update/print-once reference mode */
+  if (!*select_ok && inst->n_samples < MIN_SAMPLES_FOR_REGRESS &&
+      inst->n_samples == inst->max_samples) {
+    *std_dev = CNF_GetMaxJitter();
+    *select_ok = 1;
+  }
+
+  DEBUG_LOG("n=%d off=%f dist=%f sd=%f first_ago=%f last_ago=%f selok=%d",
+            inst->n_samples, offset, *root_distance, *std_dev,
+            *first_sample_ago, *last_sample_ago, *select_ok);
+}
+
+/* ================================================== */
+
+void
+SST_GetTrackingData(SST_Stats inst, struct timespec *ref_time,
+                    double *average_offset, double *offset_sd,
+                    double *frequency, double *frequency_sd, double *skew,
+                    double *root_delay, double *root_dispersion)
+{
+  int i, j;
+  double elapsed_sample;
+
+  assert(inst->n_samples > 0);
+
+  i = get_runsbuf_index(inst, inst->best_single_sample);
+  j = get_buf_index(inst, inst->best_single_sample);
+
+  *ref_time = inst->offset_time;
+  *average_offset = inst->estimated_offset;
+  *offset_sd = inst->estimated_offset_sd;
+  *frequency = inst->estimated_frequency;
+  *frequency_sd = inst->estimated_frequency_sd;
+  *skew = inst->skew;
+  *root_delay = inst->root_delays[j];
+
+  elapsed_sample = UTI_DiffTimespecsToDouble(&inst->offset_time, &inst->sample_times[i]);
+  *root_dispersion = inst->root_dispersions[j] + inst->skew * elapsed_sample + *offset_sd;
+
+  DEBUG_LOG("n=%d off=%f offsd=%f freq=%e freqsd=%e skew=%e delay=%f disp=%f",
+            inst->n_samples, *average_offset, *offset_sd,
+            *frequency, *frequency_sd, *skew, *root_delay, *root_dispersion);
+}
+
+/* ================================================== */
+
+void
+SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doffset)
+{
+  int m, i;
+  double delta_time;
+  struct timespec *sample, prev;
+  double prev_offset, prev_freq;
+
+  if (!inst->n_samples)
+    return;
+
+  for (m = -inst->runs_samples; m < inst->n_samples; m++) {
+    i = get_runsbuf_index(inst, m);
+    sample = &inst->sample_times[i];
+    prev = *sample;
+    UTI_AdjustTimespec(sample, when, sample, &delta_time, dfreq, doffset);
+    inst->offsets[i] += delta_time;
+  }
+
+  /* Update the regression estimates */
+  prev = inst->offset_time;
+  prev_offset = inst->estimated_offset;
+  prev_freq = inst->estimated_frequency;
+  UTI_AdjustTimespec(&inst->offset_time, when, &inst->offset_time,
+      &delta_time, dfreq, doffset);
+  inst->estimated_offset += delta_time;
+  inst->estimated_frequency = (inst->estimated_frequency - dfreq) / (1.0 - dfreq);
+
+  DEBUG_LOG("n=%d m=%d old_off_time=%s new=%s old_off=%f new_off=%f old_freq=%.3f new_freq=%.3f",
+            inst->n_samples, inst->runs_samples,
+            UTI_TimespecToString(&prev), UTI_TimespecToString(&inst->offset_time),
+            prev_offset, inst->estimated_offset,
+            1.0e6 * prev_freq, 1.0e6 * inst->estimated_frequency);
+}
+
+/* ================================================== */
+
+void
+SST_CorrectOffset(SST_Stats inst, double doffset)
+{
+  int i;
+
+  if (!inst->n_samples)
+    return;
+
+  for (i = -inst->runs_samples; i < inst->n_samples; i++)
+    inst->offsets[get_runsbuf_index(inst, i)] += doffset;
+
+  inst->estimated_offset += doffset;
+}
+
+/* ================================================== */
+
+void 
+SST_AddDispersion(SST_Stats inst, double dispersion)
+{
+  int m, i;
+
+  for (m = 0; m < inst->n_samples; m++) {
+    i = get_buf_index(inst, m);
+    inst->root_dispersions[i] += dispersion;
+    inst->peer_dispersions[i] += dispersion;
+  }
+}
+
+/* ================================================== */
+
+double
+SST_PredictOffset(SST_Stats inst, struct timespec *when)
+{
+  double elapsed;
+  
+  if (inst->n_samples < MIN_SAMPLES_FOR_REGRESS) {
+    /* We don't have any useful statistics, and presumably the poll
+       interval is minimal.  We can't do any useful prediction other
+       than use the latest sample or zero if we don't have any samples */
+    if (inst->n_samples > 0) {
+      return inst->offsets[inst->last_sample];
+    } else {
+      return 0.0;
+    }
+  } else {
+    elapsed = UTI_DiffTimespecsToDouble(when, &inst->offset_time);
+    return inst->estimated_offset + elapsed * inst->estimated_frequency;
+  }
+
+}
+
+/* ================================================== */
+
+double
+SST_MinRoundTripDelay(SST_Stats inst)
+{
+  if (inst->fixed_min_delay > 0.0)
+    return inst->fixed_min_delay;
+
+  if (!inst->n_samples)
+    return DBL_MAX;
+
+  return inst->peer_delays[inst->min_delay_sample];
+}
+
+/* ================================================== */
+
+int
+SST_GetDelayTestData(SST_Stats inst, struct timespec *sample_time,
+                     double *last_sample_ago, double *predicted_offset,
+                     double *min_delay, double *skew, double *std_dev)
+{
+  if (inst->n_samples < 6)
+    return 0;
+
+  *last_sample_ago = UTI_DiffTimespecsToDouble(sample_time, &inst->offset_time);
+  *predicted_offset = inst->estimated_offset +
+                      *last_sample_ago * inst->estimated_frequency;
+  *min_delay = SST_MinRoundTripDelay(inst);
+  *skew = inst->skew;
+  *std_dev = inst->std_dev;
+
+  return 1;
+}
+
+/* ================================================== */
+/* This is used to save the register to a file, so that we can reload
+   it after restarting the daemon */
+
+int
+SST_SaveToFile(SST_Stats inst, FILE *out)
+{
+  int m, i, j;
+
+  if (inst->n_samples < 1)
+    return 0;
+
+  if (fprintf(out, "%d %d\n", inst->n_samples, inst->asymmetry_run) < 0)
+    return 0;
+
+  for(m = 0; m < inst->n_samples; m++) {
+    i = get_runsbuf_index(inst, m);
+    j = get_buf_index(inst, m);
+
+    if (fprintf(out, "%s %.6e %.6e %.6e %.6e %.6e %.6e\n",
+                UTI_TimespecToString(&inst->sample_times[i]),
+                inst->offsets[i], inst->orig_offsets[j],
+                inst->peer_delays[i], inst->peer_dispersions[j],
+                inst->root_delays[j], inst->root_dispersions[j]) < 0)
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+/* This is used to reload samples from a file */
+
+int
+SST_LoadFromFile(SST_Stats inst, FILE *in)
+{
+  int i, n_samples, arun;
+  struct timespec now;
+  double sample_time;
+  char line[256];
+
+  if (!fgets(line, sizeof (line), in) ||
+      sscanf(line, "%d %d", &n_samples, &arun) != 2 ||
+      n_samples < 1 || n_samples > MAX_SAMPLES)
+    return 0;
+
+  SST_ResetInstance(inst);
+
+  LCL_ReadCookedTime(&now, NULL);
+
+  for (i = 0; i < n_samples; i++) {
+    if (!fgets(line, sizeof (line), in) ||
+        sscanf(line, "%lf %lf %lf %lf %lf %lf %lf",
+               &sample_time, &inst->offsets[i], &inst->orig_offsets[i],
+               &inst->peer_delays[i], &inst->peer_dispersions[i],
+               &inst->root_delays[i], &inst->root_dispersions[i]) != 7)
+      return 0;
+
+    if (!UTI_IsTimeOffsetSane(&now, sample_time - UTI_TimespecToDouble(&now)))
+      return 0;
+
+    /* Some resolution is lost in the double format, but that's ok */
+    UTI_DoubleToTimespec(sample_time, &inst->sample_times[i]);
+
+    /* Make sure the samples are sane and they are in order */
+    if (!UTI_IsTimeOffsetSane(&inst->sample_times[i], -inst->offsets[i]) ||
+        UTI_CompareTimespecs(&now, &inst->sample_times[i]) < 0 ||
+        !(fabs(inst->peer_delays[i]) < 1.0e6 && fabs(inst->peer_dispersions[i]) < 1.0e6 &&
+          fabs(inst->root_delays[i]) < 1.0e6 && fabs(inst->root_dispersions[i]) < 1.0e6) ||
+        (i > 0 && UTI_CompareTimespecs(&inst->sample_times[i],
+                                       &inst->sample_times[i - 1]) <= 0))
+      return 0;
+  }
+
+  inst->n_samples = n_samples;
+  inst->last_sample = inst->n_samples - 1;
+  inst->asymmetry_run = CLAMP(-MAX_ASYMMETRY_RUN, arun, MAX_ASYMMETRY_RUN);
+
+  find_min_delay_sample(inst);
+  SST_DoNewRegression(inst);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+SST_DoSourceReport(SST_Stats inst, RPT_SourceReport *report, struct timespec *now)
+{
+  int i, j;
+  struct timespec last_sample_time;
+
+  if (inst->n_samples > 0) {
+    i = get_runsbuf_index(inst, inst->n_samples - 1);
+    j = get_buf_index(inst, inst->n_samples - 1);
+    report->orig_latest_meas = inst->orig_offsets[j];
+    report->latest_meas = inst->offsets[i];
+    report->latest_meas_err = 0.5*inst->root_delays[j] + inst->root_dispersions[j];
+
+    /* Align the sample time to reduce the leak of the NTP receive timestamp */
+    last_sample_time = inst->sample_times[i];
+    if (inst->ip_addr)
+      last_sample_time.tv_nsec = 0;
+    report->latest_meas_ago = UTI_DiffTimespecsToDouble(now, &last_sample_time);
+  } else {
+    report->latest_meas_ago = (uint32_t)-1;
+    report->orig_latest_meas = 0;
+    report->latest_meas = 0;
+    report->latest_meas_err = 0;
+    report->stratum = 0;
+  }
+}
+
+/* ================================================== */
+
+int
+SST_Samples(SST_Stats inst)
+{
+  return inst->n_samples;
+}
+
+/* ================================================== */
+
+int
+SST_GetMinSamples(SST_Stats inst)
+{
+  return inst->min_samples;
+}
+
+/* ================================================== */
+
+void
+SST_DoSourcestatsReport(SST_Stats inst, RPT_SourcestatsReport *report, struct timespec *now)
+{
+  double dspan;
+  double elapsed, sample_elapsed;
+  int bi, bj;
+
+  report->n_samples = inst->n_samples;
+  report->n_runs = inst->nruns;
+
+  if (inst->n_samples > 0) {
+    bi = get_runsbuf_index(inst, inst->best_single_sample);
+    bj = get_buf_index(inst, inst->best_single_sample);
+
+    dspan = UTI_DiffTimespecsToDouble(&inst->sample_times[inst->last_sample],
+                                      &inst->sample_times[get_runsbuf_index(inst, 0)]);
+    elapsed = UTI_DiffTimespecsToDouble(now, &inst->offset_time);
+    sample_elapsed = UTI_DiffTimespecsToDouble(now, &inst->sample_times[bi]);
+
+    report->span_seconds = round(dspan);
+    report->est_offset = inst->estimated_offset + elapsed * inst->estimated_frequency;
+    report->est_offset_err = inst->estimated_offset_sd + sample_elapsed * inst->skew +
+                             (0.5 * inst->root_delays[bj] + inst->root_dispersions[bj]);
+  } else {
+    report->span_seconds = 0;
+    report->est_offset = 0;
+    report->est_offset_err = 0;
+  }
+
+  report->resid_freq_ppm = 1.0e6 * inst->estimated_frequency;
+  report->skew_ppm = 1.0e6 * inst->skew;
+  report->sd = inst->std_dev;
+}
+
+/* ================================================== */
+
+double
+SST_GetJitterAsymmetry(SST_Stats inst)
+{
+  return inst->asymmetry;
+}
+
+/* ================================================== */
diff --git a/sourcestats.h b/sourcestats.h
new file mode 100644
index 0000000..e10f425
--- /dev/null
+++ b/sourcestats.h
@@ -0,0 +1,141 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for module that deals with the measurements and statistics of
+  each of the sources. */
+
+#ifndef GOT_SOURCESTATS_H
+#define GOT_SOURCESTATS_H
+
+#include "sysincl.h"
+
+#include "reports.h"
+
+typedef struct SST_Stats_Record *SST_Stats;
+
+/* Init and fini functions */
+extern void SST_Initialise(void);
+extern void SST_Finalise(void);
+
+/* This function creates a new instance of the statistics handler */
+extern SST_Stats SST_CreateInstance(uint32_t refid, IPAddr *addr,
+                                    int min_samples, int max_samples,
+                                    double min_delay, double asymmetry);
+
+/* This function deletes an instance of the statistics handler. */
+extern void SST_DeleteInstance(SST_Stats inst);
+
+/* This function resets an instance */
+extern void SST_ResetInstance(SST_Stats inst);
+
+/* This function changes the reference ID and IP address */
+extern void SST_SetRefid(SST_Stats inst, uint32_t refid, IPAddr *addr);
+
+/* This function accumulates a single sample into the statistics handler */
+extern void SST_AccumulateSample(SST_Stats inst, NTP_Sample *sample);
+
+/* This function runs the linear regression operation on the data.  It
+   finds the set of most recent samples that give the tightest
+   confidence interval for the frequency, and truncates the register
+   down to that number of samples. */
+extern void SST_DoNewRegression(SST_Stats inst);
+
+/* Return the assumed worst case range of values that this source's
+   frequency lies within.  Frequency is defined as the amount of time
+   the local clock gains relative to the source per unit local clock
+   time. */
+extern void SST_GetFrequencyRange(SST_Stats inst, double *lo, double *hi);
+
+/* Get data needed for selection */
+extern void
+SST_GetSelectionData(SST_Stats inst, struct timespec *now,
+                     double *offset_lo_limit,
+                     double *offset_hi_limit,
+                     double *root_distance,
+                     double *variance,
+                     double *first_sample_ago,
+                     double *last_sample_ago,
+                     int *select_ok);
+
+/* Get data needed when setting up tracking on this source */
+extern void
+SST_GetTrackingData(SST_Stats inst, struct timespec *ref_time,
+                    double *average_offset, double *offset_sd,
+                    double *frequency, double *frequency_sd, double *skew,
+                    double *root_delay, double *root_dispersion);
+
+/* This routine is called when the local machine clock parameters are
+   changed.  It adjusts all existing samples that we are holding for
+   each peer so that it looks like they were made under the new clock
+   regime rather than the old one.
+
+   when = cooked local time when the change occurs
+
+   dfreq = delta frequency. positive means the clock has been adjusted
+   because it was previously gaining time relative to the external
+   reference(s).
+
+   doffset = offset slewed onto local clock.  positive => local clock
+   has been made fast by that amount.
+
+*/
+
+extern void SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doffset);
+
+/* This routine corrects already accumulated samples to improve the
+   frequency estimate when a new sample is accumulated */
+extern void SST_CorrectOffset(SST_Stats inst, double doffset);
+
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+extern void SST_AddDispersion(SST_Stats inst, double dispersion);
+
+/* Predict the offset of the local clock relative to a given source at
+   a given local cooked time. Positive indicates local clock is FAST
+   relative to reference. */
+extern double SST_PredictOffset(SST_Stats inst, struct timespec *when);
+
+/* Find the minimum round trip delay in the register */
+extern double SST_MinRoundTripDelay(SST_Stats inst);
+
+/* Get data needed for testing NTP delay */
+extern int SST_GetDelayTestData(SST_Stats inst, struct timespec *sample_time,
+                                double *last_sample_ago, double *predicted_offset,
+                                double *min_delay, double *skew, double *std_dev);
+
+extern int SST_SaveToFile(SST_Stats inst, FILE *out);
+
+extern int SST_LoadFromFile(SST_Stats inst, FILE *in);
+
+extern void SST_DoSourceReport(SST_Stats inst, RPT_SourceReport *report, struct timespec *now);
+
+extern void SST_DoSourcestatsReport(SST_Stats inst, RPT_SourcestatsReport *report, struct timespec *now);
+
+extern int SST_Samples(SST_Stats inst);
+
+extern int SST_GetMinSamples(SST_Stats inst);
+
+extern double SST_GetJitterAsymmetry(SST_Stats inst);
+
+#endif /* GOT_SOURCESTATS_H */
+
diff --git a/srcparams.h b/srcparams.h
new file mode 100644
index 0000000..31baed7
--- /dev/null
+++ b/srcparams.h
@@ -0,0 +1,93 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file defining parameters that can be set on a per source basis
+  */
+
+#ifndef GOT_SRCPARAMS_H
+#define GOT_SRCPARAMS_H
+
+#include "sources.h"
+
+typedef enum {
+  SRC_OFFLINE,
+  SRC_ONLINE,
+  SRC_MAYBE_ONLINE,
+} SRC_Connectivity;
+
+typedef struct {
+  int minpoll;
+  int maxpoll;
+  SRC_Connectivity connectivity;
+  int auto_offline;
+  int presend_minpoll;
+  int burst;
+  int iburst;
+  int min_stratum;
+  int poll_target;
+  int version;
+  int max_sources;
+  int min_samples;
+  int max_samples;
+  int filter_length;
+  int interleaved;
+  int sel_options;
+  int nts;
+  int nts_port;
+  int copy;
+  int ext_fields;
+  uint32_t authkey;
+  uint32_t cert_set;
+  double max_delay;
+  double max_delay_ratio;
+  double max_delay_dev_ratio;
+  double max_delay_quant;
+  double min_delay;
+  double asymmetry;
+  double offset;
+} SourceParameters;
+
+#define SRC_DEFAULT_PORT 123
+#define SRC_DEFAULT_MINPOLL 6
+#define SRC_DEFAULT_MAXPOLL 10
+#define SRC_DEFAULT_PRESEND_MINPOLL 100
+#define SRC_DEFAULT_MAXDELAY 3.0
+#define SRC_DEFAULT_MAXDELAYRATIO 0.0
+#define SRC_DEFAULT_MAXDELAYDEVRATIO 10.0
+#define SRC_DEFAULT_MINSTRATUM 0
+#define SRC_DEFAULT_POLLTARGET 8
+#define SRC_DEFAULT_MAXSOURCES 4
+#define SRC_DEFAULT_MINSAMPLES (-1)
+#define SRC_DEFAULT_MAXSAMPLES (-1)
+#define SRC_DEFAULT_ASYMMETRY 1.0
+#define SRC_DEFAULT_NTSPORT 4460
+#define SRC_DEFAULT_CERTSET 0
+#define INACTIVE_AUTHKEY 0
+
+/* Flags for source selection */
+#define SRC_SELECT_NOSELECT 0x1
+#define SRC_SELECT_PREFER 0x2
+#define SRC_SELECT_TRUST 0x4
+#define SRC_SELECT_REQUIRE 0x8
+
+#endif /* GOT_SRCPARAMS_H */
diff --git a/stubs.c b/stubs.c
new file mode 100644
index 0000000..cb7b9a6
--- /dev/null
+++ b/stubs.c
@@ -0,0 +1,567 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014-2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Function replacements needed when optional features are disabled.
+
+  */
+
+#include "config.h"
+
+#include "clientlog.h"
+#include "cmac.h"
+#include "cmdmon.h"
+#include "keys.h"
+#include "logging.h"
+#include "manual.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "nameserv_async.h"
+#include "ntp_core.h"
+#include "ntp_io.h"
+#include "ntp_sources.h"
+#include "ntp_signd.h"
+#include "nts_ke_client.h"
+#include "nts_ke_server.h"
+#include "nts_ntp_client.h"
+#include "nts_ntp_server.h"
+#include "privops.h"
+#include "refclock.h"
+#include "sched.h"
+#include "util.h"
+
+#if defined(FEAT_NTP) && !defined(FEAT_ASYNCDNS)
+
+/* This is a blocking implementation used when asynchronous resolving is not available */
+
+struct DNS_Async_Instance {
+  const char *name;
+  DNS_NameResolveHandler handler;
+  void *arg;
+  int pipe[2];
+};
+
+static void
+resolve_name(int fd, int event, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+  IPAddr addrs[DNS_MAX_ADDRESSES];
+  DNS_Status status;
+  int i;
+
+  inst = (struct DNS_Async_Instance *)anything;
+
+  SCH_RemoveFileHandler(inst->pipe[0]);
+  close(inst->pipe[0]);
+  close(inst->pipe[1]);
+
+  status = PRV_Name2IPAddress(inst->name, addrs, DNS_MAX_ADDRESSES);
+
+  for (i = 0; status == DNS_Success && i < DNS_MAX_ADDRESSES &&
+       addrs[i].family != IPADDR_UNSPEC; i++)
+    ;
+
+  (inst->handler)(status, i, addrs, inst->arg);
+
+  Free(inst);
+}
+
+void
+DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
+{
+  struct DNS_Async_Instance *inst;
+
+  inst = MallocNew(struct DNS_Async_Instance);
+  inst->name = name;
+  inst->handler = handler;
+  inst->arg = anything;
+
+  if (pipe(inst->pipe))
+    LOG_FATAL("pipe() failed");
+
+  UTI_FdSetCloexec(inst->pipe[0]);
+  UTI_FdSetCloexec(inst->pipe[1]);
+
+  SCH_AddFileHandler(inst->pipe[0], SCH_FILE_INPUT, resolve_name, inst);
+
+  if (write(inst->pipe[1], "", 1) < 0)
+    ;
+}
+
+#endif /* !FEAT_ASYNCDNS */
+
+#ifndef FEAT_CMDMON
+
+void
+CAM_Initialise(void)
+{
+}
+
+void
+CAM_Finalise(void)
+{
+}
+
+void
+CAM_OpenUnixSocket(void)
+{
+}
+
+int
+CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+{
+  return 1;
+}
+
+void
+MNL_Initialise(void)
+{
+}
+
+void
+MNL_Finalise(void)
+{
+}
+
+#endif /* !FEAT_CMDMON */
+
+#ifndef FEAT_NTP
+
+void
+NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval)
+{
+}
+
+void
+NCR_Initialise(void)
+{
+}
+
+void
+NCR_Finalise(void)
+{
+}
+
+int
+NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
+{
+  return 1;
+}
+
+int
+NCR_CheckAccessRestriction(IPAddr *ip_addr)
+{
+  return 0;
+}
+
+void
+NIO_Initialise(void)
+{
+}
+
+void
+NIO_Finalise(void)
+{
+}
+
+void
+NSR_Initialise(void)
+{
+}
+
+void
+NSR_Finalise(void)
+{
+}
+
+NSR_Status
+NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+              SourceParameters *params, uint32_t *conf_id)
+{
+  return NSR_TooManySources;
+}
+
+NSR_Status
+NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
+                    SourceParameters *params, uint32_t *conf_id)
+{
+  return NSR_TooManySources;
+}
+
+NSR_Status
+NSR_RemoveSource(IPAddr *address)
+{
+  return NSR_NoSuchSource;
+}
+
+void
+NSR_RemoveSourcesById(uint32_t conf_id)
+{
+}
+
+void
+NSR_RemoveAllSources(void)
+{
+}
+
+void
+NSR_HandleBadSource(IPAddr *address)
+{
+}
+
+void
+NSR_RefreshAddresses(void)
+{
+}
+
+char *
+NSR_GetName(IPAddr *address)
+{
+  return NULL;
+}
+
+void
+NSR_SetSourceResolvingEndHandler(NSR_SourceResolvingEndHandler handler)
+{
+  if (handler)
+    (handler)();
+}
+
+void
+NSR_ResolveSources(void)
+{
+}
+
+void NSR_StartSources(void)
+{
+}
+
+void NSR_AutoStartSources(void)
+{
+}
+
+int
+NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples,
+                        IPAddr *mask, IPAddr *address)
+{
+  return 0;
+}
+
+uint32_t
+NSR_GetLocalRefid(IPAddr *address)
+{
+  return 0;
+}
+
+int
+NSR_SetConnectivity(IPAddr *mask, IPAddr *address, SRC_Connectivity connectivity)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMinpoll(IPAddr *address, int new_minpoll)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxpoll(IPAddr *address, int new_maxpoll)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelay(IPAddr *address, double new_max_delay)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelayratio(IPAddr *address, double new_max_delay_ratio)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMaxdelaydevratio(IPAddr *address, double new_max_delay_dev_ratio)
+{
+  return 0;
+}
+
+int
+NSR_ModifyMinstratum(IPAddr *address, int new_min_stratum)
+{
+  return 0;
+}
+
+int
+NSR_ModifyPolltarget(IPAddr *address, int new_poll_target)
+{
+  return 0;
+}
+
+void
+NSR_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  memset(report, 0, sizeof (*report));
+}
+  
+int
+NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report)
+{
+  return 0;
+}
+
+int
+NSR_GetNTPReport(RPT_NTPReport *report)
+{
+  return 0;
+}
+
+void
+NSR_GetActivityReport(RPT_ActivityReport *report)
+{
+  memset(report, 0, sizeof (*report));
+}
+
+void
+NSR_DumpAuthData(void)
+{
+}
+
+#ifndef FEAT_CMDMON
+
+void
+CLG_Initialise(void)
+{
+}
+
+void
+CLG_Finalise(void)
+{
+}
+
+void
+DNS_SetAddressFamily(int family)
+{
+}
+
+DNS_Status
+DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  return DNS_Failure;
+}
+
+void
+KEY_Initialise(void)
+{
+}
+
+void
+KEY_Finalise(void)
+{
+}
+
+#endif /* !FEAT_CMDMON */
+#endif /* !FEAT_NTP */
+
+#ifndef FEAT_REFCLOCK
+void
+RCL_Initialise(void)
+{
+}
+
+void
+RCL_Finalise(void)
+{
+}
+
+int
+RCL_AddRefclock(RefclockParameters *params)
+{
+  return 0;
+}
+
+void
+RCL_StartRefclocks(void)
+{
+}
+
+void
+RCL_ReportSource(RPT_SourceReport *report, struct timespec *now)
+{
+  memset(report, 0, sizeof (*report));
+}
+
+#endif /* !FEAT_REFCLOCK */
+
+#ifndef FEAT_SIGND
+
+void
+NSD_Initialise(void)
+{
+}
+
+void
+NSD_Finalise(void)
+{
+}
+
+int
+NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
+                      NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
+{
+  return 0;
+}
+
+#endif /* !FEAT_SIGND */
+
+#ifndef HAVE_CMAC
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  return 0;
+}
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  return NULL;
+}
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  return 0;
+}
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+}
+
+#endif /* !HAVE_CMAC */
+
+#ifndef FEAT_NTS
+
+void
+NNS_Initialise(void)
+{
+}
+
+void
+NNS_Finalise(void)
+{
+}
+
+int
+NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
+{
+  *kod = 0;
+  return 0;
+}
+
+int
+NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
+                         NTP_Packet *response, NTP_PacketInfo *res_info,
+                         uint32_t kod)
+{
+  return 0;
+}
+
+NNC_Instance
+NNC_CreateInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set,
+                   uint16_t ntp_port)
+{
+  return NULL;
+}
+
+void
+NNC_DestroyInstance(NNC_Instance inst)
+{
+}
+
+int
+NNC_PrepareForAuth(NNC_Instance inst)
+{
+  return 1;
+}
+
+int
+NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  static int logged = 0;
+
+  LOG(logged ? LOGS_DEBUG : LOGS_WARN, "Missing NTS support");
+  logged = 1;
+  return 0;
+}
+
+int
+NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  return 0;
+}
+
+void
+NNC_ChangeAddress(NNC_Instance inst, IPAddr *address)
+{
+}
+
+void
+NNC_DumpData(NNC_Instance inst)
+{
+}
+
+void
+NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report)
+{
+}
+
+void
+NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level)
+{
+}
+
+void
+NKS_Initialise(void)
+{
+}
+
+void
+NKS_Finalise(void)
+{
+}
+
+void
+NKS_DumpKeys(void)
+{
+}
+
+void
+NKS_ReloadKeys(void)
+{
+}
+
+#endif /* !FEAT_NTS */
diff --git a/sys.c b/sys.c
new file mode 100644
index 0000000..1a1a432
--- /dev/null
+++ b/sys.c
@@ -0,0 +1,150 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file contains all the conditionally compiled bits that pull
+  in the various operating-system specific modules
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys.h"
+#include "sys_null.h"
+#include "logging.h"
+
+#if defined(LINUX)
+#include "sys_linux.h"
+#include "sys_posix.h"
+#elif defined(SOLARIS)
+#include "sys_solaris.h"
+#include "sys_posix.h"
+#elif defined(NETBSD) || defined(FREEBSD)
+#include "sys_netbsd.h"
+#include "sys_posix.h"
+#elif defined(MACOSX)
+#include "sys_macosx.h"
+#endif
+
+/* ================================================== */
+
+static int null_driver;
+
+/* ================================================== */
+
+void
+SYS_Initialise(int clock_control)
+{
+  null_driver = !clock_control;
+  if (null_driver) {
+    SYS_Null_Initialise();
+    return;
+  }
+#if defined(LINUX)
+  SYS_Linux_Initialise();
+#elif defined(SOLARIS)
+  SYS_Solaris_Initialise();
+#elif defined(NETBSD) || defined(FREEBSD)
+  SYS_NetBSD_Initialise();
+#elif defined(MACOSX)
+  SYS_MacOSX_Initialise();
+#else
+#error Unknown system
+#endif
+}
+
+/* ================================================== */
+
+void
+SYS_Finalise(void)
+{
+  if (null_driver) {
+    SYS_Null_Finalise();
+    return;
+  }
+#if defined(LINUX)
+  SYS_Linux_Finalise();
+#elif defined(SOLARIS)
+  SYS_Solaris_Finalise();
+#elif defined(NETBSD) || defined(FREEBSD)
+  SYS_NetBSD_Finalise();
+#elif defined(MACOSX)
+  SYS_MacOSX_Finalise();
+#else
+#error Unknown system
+#endif
+}
+
+/* ================================================== */
+
+void SYS_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+#if defined(LINUX) && defined (FEAT_PRIVDROP)
+  SYS_Linux_DropRoot(uid, gid, context, !null_driver);
+#elif defined(SOLARIS) && defined(FEAT_PRIVDROP)
+  SYS_Solaris_DropRoot(uid, gid, context);
+#elif (defined(NETBSD) || defined(FREEBSD)) && defined(FEAT_PRIVDROP)
+  SYS_NetBSD_DropRoot(uid, gid, context, !null_driver);
+#elif defined(MACOSX) && defined(FEAT_PRIVDROP)
+  SYS_MacOSX_DropRoot(uid, gid, context);
+#else
+  LOG_FATAL("dropping root privileges not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_EnableSystemCallFilter(int level, SYS_ProcessContext context)
+{
+#if defined(LINUX) && defined(FEAT_SCFILTER)
+  SYS_Linux_EnableSystemCallFilter(level, context);
+#else
+  LOG_FATAL("system call filter not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_SetScheduler(int SchedPriority)
+{
+#if defined(MACOSX)
+  SYS_MacOSX_SetScheduler(SchedPriority);
+#elif defined(HAVE_PTHREAD_SETSCHEDPARAM)
+  SYS_Posix_SetScheduler(SchedPriority);
+#else
+  LOG_FATAL("scheduler priority setting not supported");
+#endif
+}
+
+/* ================================================== */
+
+void SYS_LockMemory(void)
+{
+#if defined(HAVE_MLOCKALL)
+  SYS_Posix_MemLockAll();
+#else
+  LOG_FATAL("memory locking not supported");
+#endif
+}
+
+/* ================================================== */
diff --git a/sys.h b/sys.h
new file mode 100644
index 0000000..9272daf
--- /dev/null
+++ b/sys.h
@@ -0,0 +1,53 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header for the file that links in the operating system-
+  specific parts of the software
+
+*/
+
+#ifndef GOT_SYS_H
+#define GOT_SYS_H
+
+/* Called at the start of the run to do initialisation */
+extern void SYS_Initialise(int clock_control);
+
+/* Called at the end of the run to do final clean-up */
+extern void SYS_Finalise(void);
+
+typedef enum {
+  SYS_MAIN_PROCESS,
+  SYS_NTSKE_HELPER,
+} SYS_ProcessContext;
+
+/* Switch to the specified user and group in given context */
+extern void SYS_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+
+/* Enable a system call filter to allow only system calls
+   which chronyd normally needs after initialization */
+extern void SYS_EnableSystemCallFilter(int level, SYS_ProcessContext context);
+
+extern void SYS_SetScheduler(int SchedPriority);
+extern void SYS_LockMemory(void);
+
+#endif /* GOT_SYS_H */
diff --git a/sys_generic.c b/sys_generic.c
new file mode 100644
index 0000000..5c42df1
--- /dev/null
+++ b/sys_generic.c
@@ -0,0 +1,449 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014-2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Generic driver functions to complete system-specific drivers
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_generic.h"
+
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "privops.h"
+#include "sched.h"
+#include "util.h"
+
+/* ================================================== */
+
+/* System clock drivers */
+static lcl_ReadFrequencyDriver drv_read_freq;
+static lcl_SetFrequencyDriver drv_set_freq;
+static lcl_SetSyncStatusDriver drv_set_sync_status;
+static lcl_AccrueOffsetDriver drv_accrue_offset;
+static lcl_OffsetCorrectionDriver drv_get_offset_correction;
+
+/* Current frequency as requested by the local module (in ppm) */
+static double base_freq;
+
+/* Maximum frequency that can be set by drv_set_freq (in ppm) */
+static double max_freq;
+
+/* Maximum expected delay in the actual frequency change (e.g. kernel ticks)
+   in local time */
+static double max_freq_change_delay;
+
+/* Maximum allowed frequency offset relative to the base frequency */
+static double max_corr_freq;
+
+/* Amount of outstanding offset to process */
+static double offset_register;
+
+/* Minimum offset to correct */
+#define MIN_OFFSET_CORRECTION 1.0e-9
+
+/* Current frequency offset between base_freq and the real clock frequency
+   as set by drv_set_freq (not in ppm) */
+static double slew_freq;
+
+/* Time (raw) of last update of slewing frequency and offset */
+static struct timespec slew_start;
+
+/* Limits for the slew length */
+#define MIN_SLEW_DURATION 1.0
+#define MAX_SLEW_DURATION 1.0e4
+
+/* Scheduler timeout ID for ending of the currently running slew */
+static SCH_TimeoutID slew_timeout_id;
+
+/* Scheduled duration of the currently running slew */
+static double slew_duration;
+
+/* Expected delay in ending of the slew due to process scheduling and
+   execution time, tracked as a decaying maximum value */
+static double slew_excess_duration;
+
+/* Maximum accepted excess duration to ignore large jumps after resuming
+   suspended system and other reasons (which should be handled in the
+   scheduler), a constant to determine the minimum slew duration to avoid
+   oscillations due to the excess, and the decay constant */
+#define MAX_SLEW_EXCESS_DURATION 100.0
+#define MIN_SLEW_DURATION_EXCESS_RATIO 5.0
+#define SLEW_EXCESS_DURATION_DECAY 0.9
+
+/* Suggested offset correction rate (correction time * offset) */
+static double correction_rate;
+
+/* Maximum expected offset correction error caused by delayed change in the
+   real frequency of the clock */
+static double slew_error;
+
+/* Minimum offset that the system driver can slew faster than the maximum
+   frequency offset that it allows to be set directly */
+static double fastslew_min_offset;
+
+/* Maximum slew rate of the system driver */
+static double fastslew_max_rate;
+
+/* Flag indicating that the system driver is currently slewing */
+static int fastslew_active;
+
+/* ================================================== */
+
+static void handle_end_of_slew(void *anything);
+static void update_slew(void);
+
+/* ================================================== */
+/* Adjust slew_start on clock step */
+
+static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type == LCL_ChangeStep) {
+    UTI_AddDoubleToTimespec(&slew_start, -doffset, &slew_start);
+  }
+}
+
+/* ================================================== */
+
+static void
+start_fastslew(void)
+{
+  if (!drv_accrue_offset)
+    return;
+
+  drv_accrue_offset(offset_register, 0.0);
+
+  DEBUG_LOG("fastslew offset=%e", offset_register);
+
+  offset_register = 0.0;
+  fastslew_active = 1;
+}
+
+/* ================================================== */
+
+static void
+stop_fastslew(struct timespec *now)
+{
+  double corr;
+
+  if (!drv_get_offset_correction || !fastslew_active)
+    return;
+
+  /* Cancel the remaining offset */
+  drv_get_offset_correction(now, &corr, NULL);
+  drv_accrue_offset(corr, 0.0);
+  offset_register -= corr;
+}
+
+/* ================================================== */
+
+static double
+clamp_freq(double freq)
+{
+  if (freq > max_freq)
+    return max_freq;
+  if (freq < -max_freq)
+    return -max_freq;
+  return freq;
+}
+
+/* ================================================== */
+/* End currently running slew and start a new one */
+
+static void
+update_slew(void)
+{
+  double old_slew_freq, total_freq, corr_freq, duration, excess_duration;
+  struct timespec now, end_of_slew;
+
+  /* Remove currently running timeout */
+  SCH_RemoveTimeout(slew_timeout_id);
+
+  LCL_ReadRawTime(&now);
+
+  /* Adjust the offset register by achieved slew */
+  duration = UTI_DiffTimespecsToDouble(&now, &slew_start);
+  offset_register -= slew_freq * duration;
+
+  stop_fastslew(&now);
+
+  /* Update the maximum excess duration, decaying even when the slew did
+     not time out (i.e. frequency was set or offset accrued), but add a small
+     value to avoid denormals */
+  slew_excess_duration = (slew_excess_duration + 1.0e-9) * SLEW_EXCESS_DURATION_DECAY;
+  excess_duration = duration - slew_duration;
+  if (slew_excess_duration < excess_duration &&
+      excess_duration <= MAX_SLEW_EXCESS_DURATION)
+    slew_excess_duration = excess_duration;
+
+  /* Calculate the duration of the new slew, considering the current correction
+     rate and previous delays in stopping of the slew */
+  if (fabs(offset_register) < MIN_OFFSET_CORRECTION) {
+    duration = MAX_SLEW_DURATION;
+  } else {
+    duration = correction_rate / fabs(offset_register);
+    if (duration < MIN_SLEW_DURATION)
+      duration = MIN_SLEW_DURATION;
+    if (duration < MIN_SLEW_DURATION_EXCESS_RATIO * slew_excess_duration)
+      duration = MIN_SLEW_DURATION_EXCESS_RATIO * slew_excess_duration;
+  }
+
+  /* Get frequency offset needed to slew the offset in the duration
+     and clamp it to the allowed maximum */
+  corr_freq = offset_register / duration;
+  if (corr_freq < -max_corr_freq)
+    corr_freq = -max_corr_freq;
+  else if (corr_freq > max_corr_freq)
+    corr_freq = max_corr_freq;
+
+  /* Let the system driver perform the slew if the requested frequency
+     offset is too large for the frequency driver */
+  if (drv_accrue_offset && fabs(corr_freq) >= fastslew_max_rate &&
+      fabs(offset_register) > fastslew_min_offset) {
+    start_fastslew();
+    corr_freq = 0.0;
+  }
+
+  /* Get the new real frequency and clamp it */
+  total_freq = clamp_freq(base_freq + corr_freq * (1.0e6 - base_freq));
+
+  /* Set the new frequency (the actual frequency returned by the call may be
+     slightly different from the requested frequency due to rounding) */
+  total_freq = (*drv_set_freq)(total_freq);
+
+  /* Compute the new slewing frequency, it's relative to the real frequency to
+     make the calculation in offset_convert() cheaper */
+  old_slew_freq = slew_freq;
+  slew_freq = (total_freq - base_freq) / (1.0e6 - total_freq);
+
+  /* Compute the dispersion introduced by changing frequency and add it
+     to all statistics held at higher levels in the system */
+  slew_error = fabs((old_slew_freq - slew_freq) * max_freq_change_delay);
+  if (slew_error >= MIN_OFFSET_CORRECTION)
+    lcl_InvokeDispersionNotifyHandlers(slew_error);
+
+  /* Compute the duration of the slew and clamp it.  If the slewing frequency
+     is zero or has wrong sign (e.g. due to rounding in the frequency driver or
+     when base_freq is larger than max_freq, or fast slew is active), use the
+     maximum timeout and try again on the next update. */
+  if (fabs(offset_register) < MIN_OFFSET_CORRECTION ||
+      offset_register * slew_freq <= 0.0) {
+    duration = MAX_SLEW_DURATION;
+  } else {
+    duration = offset_register / slew_freq;
+    if (duration < MIN_SLEW_DURATION)
+      duration = MIN_SLEW_DURATION;
+    else if (duration > MAX_SLEW_DURATION)
+      duration = MAX_SLEW_DURATION;
+  }
+
+  /* Restart timer for the next update */
+  UTI_AddDoubleToTimespec(&now, duration, &end_of_slew);
+  slew_timeout_id = SCH_AddTimeout(&end_of_slew, handle_end_of_slew, NULL);
+  slew_start = now;
+  slew_duration = duration;
+
+  DEBUG_LOG("slew offset=%e corr_rate=%e base_freq=%f total_freq=%f slew_freq=%e"
+            " duration=%f excess=%f slew_error=%e",
+            offset_register, correction_rate, base_freq, total_freq, slew_freq,
+            slew_duration, slew_excess_duration, slew_error);
+}
+
+/* ================================================== */
+
+static void
+handle_end_of_slew(void *anything)
+{
+  slew_timeout_id = 0;
+  update_slew();
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return base_freq;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  base_freq = freq_ppm;
+  update_slew();
+
+  return base_freq;
+}
+
+/* ================================================== */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  offset_register += offset;
+  correction_rate = corr_rate;
+
+  update_slew();
+}
+
+/* ================================================== */
+/* Determine the correction to generate the cooked time for given raw time */
+
+static void
+offset_convert(struct timespec *raw,
+               double *corr, double *err)
+{
+  double duration, fastslew_corr, fastslew_err;
+
+  duration = UTI_DiffTimespecsToDouble(raw, &slew_start);
+
+  if (drv_get_offset_correction && fastslew_active) {
+    drv_get_offset_correction(raw, &fastslew_corr, &fastslew_err);
+    if (fastslew_corr == 0.0 && fastslew_err == 0.0)
+      fastslew_active = 0;
+  } else {
+    fastslew_corr = fastslew_err = 0.0;
+  }
+
+  *corr = slew_freq * duration + fastslew_corr - offset_register;
+
+  if (err) {
+    *err = fastslew_err;
+    if (fabs(duration) <= max_freq_change_delay)
+      *err += slew_error;
+  }
+}
+
+/* ================================================== */
+/* Positive means currently fast of true time, i.e. jump backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timespec old_time, new_time;
+  struct timeval new_time_tv;
+  double err;
+
+  LCL_ReadRawTime(&old_time);
+  UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
+  UTI_TimespecToTimeval(&new_time, &new_time_tv);
+
+  if (PRV_SetTime(&new_time_tv, NULL) < 0) {
+    DEBUG_LOG("settimeofday() failed");
+    return 0;
+  }
+
+  LCL_ReadRawTime(&old_time);
+  err = UTI_DiffTimespecsToDouble(&old_time, &new_time);
+
+  lcl_InvokeDispersionNotifyHandlers(fabs(err));
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double offset;
+
+  offset = fabs(offset_register);
+  if (est_error < offset)
+    est_error = offset;
+  max_error += offset;
+
+  if (drv_set_sync_status)
+    drv_set_sync_status(synchronised, est_error, max_error);
+}
+
+/* ================================================== */
+
+void
+SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
+                               lcl_ReadFrequencyDriver sys_read_freq,
+                               lcl_SetFrequencyDriver sys_set_freq,
+                               lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                               double min_fastslew_offset, double max_fastslew_rate,
+                               lcl_AccrueOffsetDriver sys_accrue_offset,
+                               lcl_OffsetCorrectionDriver sys_get_offset_correction,
+                               lcl_SetLeapDriver sys_set_leap,
+                               lcl_SetSyncStatusDriver sys_set_sync_status)
+{
+  max_freq = max_set_freq_ppm;
+  max_freq_change_delay = max_set_freq_delay * (1.0 + max_freq / 1.0e6);
+  drv_read_freq = sys_read_freq;
+  drv_set_freq = sys_set_freq;
+  drv_accrue_offset = sys_accrue_offset;
+  drv_get_offset_correction = sys_get_offset_correction;
+  drv_set_sync_status = sys_set_sync_status;
+
+  base_freq = (*drv_read_freq)();
+  slew_freq = 0.0;
+  offset_register = 0.0;
+  slew_excess_duration = 0.0;
+
+  max_corr_freq = CNF_GetMaxSlewRate() / 1.0e6;
+
+  fastslew_min_offset = min_fastslew_offset;
+  fastslew_max_rate = max_fastslew_rate / 1.0e6;
+  fastslew_active = 0;
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency,
+                            accrue_offset, sys_apply_step_offset ?
+                              sys_apply_step_offset : apply_step_offset,
+                            offset_convert, sys_set_leap, set_sync_status);
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Generic_Finalise(void)
+{
+  struct timespec now;
+
+  /* Must *NOT* leave a slew running - clock could drift way off
+     if the daemon is not restarted */
+
+  SCH_RemoveTimeout(slew_timeout_id);
+  slew_timeout_id = 0;
+
+  (*drv_set_freq)(clamp_freq(base_freq));
+
+  LCL_ReadRawTime(&now);
+  stop_fastslew(&now);
+
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);
+}
+
+/* ================================================== */
diff --git a/sys_generic.h b/sys_generic.h
new file mode 100644
index 0000000..d9b252e
--- /dev/null
+++ b/sys_generic.h
@@ -0,0 +1,46 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for generic driver
+  */
+
+#ifndef GOT_SYS_GENERIC_H
+#define GOT_SYS_GENERIC_H
+
+#include "localp.h"
+
+/* Register a completed driver that implements offset functions on top of
+   provided frequency functions */
+extern void SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
+                                           lcl_ReadFrequencyDriver sys_read_freq,
+                                           lcl_SetFrequencyDriver sys_set_freq,
+                                           lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                           double min_fastslew_offset, double max_fastslew_rate,
+                                           lcl_AccrueOffsetDriver sys_accrue_offset,
+                                           lcl_OffsetCorrectionDriver sys_get_offset_correction,
+                                           lcl_SetLeapDriver sys_set_leap,
+                                           lcl_SetSyncStatusDriver sys_set_sync_status);
+
+extern void SYS_Generic_Finalise(void);
+
+#endif  /* GOT_SYS_GENERIC_H */
diff --git a/sys_linux.c b/sys_linux.c
new file mode 100644
index 0000000..6849637
--- /dev/null
+++ b/sys_linux.c
@@ -0,0 +1,1025 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This is the module specific to the Linux operating system.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <sys/utsname.h>
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+#include <linux/ptp_clock.h>
+#include <poll.h>
+#endif
+
+#ifdef FEAT_SCFILTER
+#include <sys/prctl.h>
+#include <seccomp.h>
+#include <termios.h>
+#ifdef FEAT_PPS
+#include <linux/pps.h>
+#endif
+#ifdef FEAT_RTC
+#include <linux/rtc.h>
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+#include <linux/sockios.h>
+#endif
+#endif
+
+#ifdef FEAT_PRIVDROP
+#include <sys/prctl.h>
+#include <sys/capability.h>
+#endif
+
+#include "sys_linux.h"
+#include "sys_timex.h"
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "privops.h"
+#include "util.h"
+
+/* Frequency scale to convert from ppm to the timex freq */
+#define FREQ_SCALE (double)(1 << 16)
+
+/* Definitions used if missed in the system headers */
+#ifndef ADJ_SETOFFSET
+#define ADJ_SETOFFSET           0x0100  /* add 'time' to current time */
+#endif
+#ifndef ADJ_NANO
+#define ADJ_NANO                0x2000  /* select nanosecond resolution */
+#endif
+
+/* This is the uncompensated system tick value */
+static int nominal_tick;
+
+/* Current tick value */
+static int current_delta_tick;
+
+/* The maximum amount by which 'tick' can be biased away from 'nominal_tick'
+   (sys_adjtimex() in the kernel bounds this to 10%) */
+static int max_tick_bias;
+
+/* The kernel USER_HZ constant */
+static int hz;
+static double dhz; /* And dbl prec version of same for arithmetic */
+
+/* Flag indicating whether adjtimex() can step the clock */
+static int have_setoffset;
+
+/* The assumed rate at which the effective frequency and tick values are
+   updated in the kernel */
+static int tick_update_hz;
+
+/* ================================================== */
+/* Positive means currently fast of true time, i.e. jump backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timex txc;
+
+  txc.modes = ADJ_SETOFFSET | ADJ_NANO;
+  txc.time.tv_sec = -offset;
+  txc.time.tv_usec = 1.0e9 * (-offset - txc.time.tv_sec);
+  if (txc.time.tv_usec < 0) {
+    txc.time.tv_sec--;
+    txc.time.tv_usec += 1000000000;
+  }
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+/* This call sets the Linux kernel frequency to a given value in parts
+   per million relative to the nominal running frequency.  Nominal is taken to
+   be tick=10000, freq=0 (for a USER_HZ==100 system, other values otherwise).
+   The convention is that this is called with a positive argument if the local
+   clock runs fast when uncompensated.  */
+
+static double
+set_frequency(double freq_ppm)
+{
+  struct timex txc;
+  long required_tick;
+  double required_freq;
+  int required_delta_tick;
+
+  required_delta_tick = round(freq_ppm / dhz);
+
+  /* Older kernels (pre-2.6.18) don't apply the frequency offset exactly as
+     set by adjtimex() and a scaling constant (that depends on the internal
+     kernel HZ constant) would be needed to compensate for the error. Because
+     chronyd is closed loop it doesn't matter much if we don't scale the
+     required frequency, but we want to prevent thrashing between two states
+     when the system's frequency error is close to a multiple of USER_HZ.  With
+     USER_HZ <= 250, the maximum frequency adjustment of 500 ppm overlaps at
+     least two ticks and we can stick to the current tick if it's next to the
+     required tick. */
+  if (hz <= 250 && (required_delta_tick + 1 == current_delta_tick ||
+                    required_delta_tick - 1 == current_delta_tick)) {
+    required_delta_tick = current_delta_tick;
+  }
+
+  required_freq = -(freq_ppm - dhz * required_delta_tick);
+  required_tick = nominal_tick - required_delta_tick;
+
+  txc.modes = ADJ_TICK | ADJ_FREQUENCY;
+  txc.freq = required_freq * FREQ_SCALE;
+  txc.tick = required_tick;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  current_delta_tick = required_delta_tick;
+
+  return dhz * current_delta_tick - txc.freq / FREQ_SCALE;
+}
+
+/* ================================================== */
+/* Read the ppm frequency from the kernel */
+
+static double
+read_frequency(void)
+{
+  struct timex txc;
+
+  txc.modes = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  current_delta_tick = nominal_tick - txc.tick;
+
+  return dhz * current_delta_tick - txc.freq / FREQ_SCALE;
+}
+
+/* ================================================== */
+
+/* Estimate the value of USER_HZ given the value of txc.tick that chronyd finds when
+ * it starts.  The only credible values are 100 (Linux/x86) or powers of 2.
+ * Also, the bounds checking inside the kernel's adjtimex system call enforces
+ * a +/- 10% movement of tick away from the nominal value 1e6/USER_HZ. */
+
+static int
+guess_hz(void)
+{
+  struct timex txc;
+  int i, tick, tick_lo, tick_hi, ihz;
+  double tick_nominal;
+
+  txc.modes = 0;
+  SYS_Timex_Adjust(&txc, 0);
+  tick = txc.tick;
+
+  /* Pick off the hz=100 case first */
+  if (tick >= 9000 && tick <= 11000) {
+    return 100;
+  }
+
+  for (i=4; i<16; i++) { /* surely 16 .. 32768 is a wide enough range? */
+    ihz = 1 << i;
+    tick_nominal = 1.0e6 / (double) ihz;
+    tick_lo = (int)(0.5 + tick_nominal*2.0/3.0);
+    tick_hi = (int)(0.5 + tick_nominal*4.0/3.0);
+    
+    if (tick_lo < tick && tick <= tick_hi) {
+      return ihz;
+    }
+  }
+
+  /* oh dear.  doomed. */
+  LOG_FATAL("Can't determine hz from tick %d", tick);
+
+  return 0;
+}
+
+/* ================================================== */
+
+static int
+get_hz(void)
+{
+#ifdef _SC_CLK_TCK
+  int hz;
+
+  if ((hz = sysconf(_SC_CLK_TCK)) < 1)
+    return 0;
+
+  return hz;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+kernelvercmp(int major1, int minor1, int patch1,
+    int major2, int minor2, int patch2)
+{
+  if (major1 != major2)
+    return major1 - major2;
+  if (minor1 != minor2)
+    return minor1 - minor2;
+  return patch1 - patch2;
+}
+
+/* ================================================== */
+
+static void
+get_kernel_version(int *major, int *minor, int *patch)
+{
+  struct utsname uts;
+
+  if (uname(&uts) < 0)
+    LOG_FATAL("uname() failed");
+
+  *patch = 0;
+  if (sscanf(uts.release, "%d.%d.%d", major, minor, patch) < 2)
+    LOG_FATAL("Could not parse kernel version");
+}
+
+/* ================================================== */
+
+/* Compute the scaling to use on any frequency we set, according to
+   the vintage of the Linux kernel being used. */
+
+static void
+get_version_specific_details(void)
+{
+  int major, minor, patch;
+  
+  hz = get_hz();
+
+  if (!hz)
+    hz = guess_hz();
+
+  dhz = (double) hz;
+  nominal_tick = (1000000L + (hz/2))/hz; /* Mirror declaration in kernel */
+  max_tick_bias = nominal_tick / 10;
+
+  /* In modern kernels the frequency of the clock is updated immediately in the
+     adjtimex() system call.  Assume a maximum delay of 10 microseconds. */
+  tick_update_hz = 100000;
+
+  get_kernel_version(&major, &minor, &patch);
+  DEBUG_LOG("Linux kernel major=%d minor=%d patch=%d", major, minor, patch);
+
+  if (kernelvercmp(major, minor, patch, 2, 2, 0) < 0) {
+    LOG_FATAL("Kernel version not supported, sorry.");
+  }
+
+  if (kernelvercmp(major, minor, patch, 2, 6, 27) >= 0 &&
+      kernelvercmp(major, minor, patch, 2, 6, 33) < 0) {
+    /* In tickless kernels before 2.6.33 the frequency is updated in
+       a half-second interval */
+    tick_update_hz = 2;
+  } else if (kernelvercmp(major, minor, patch, 4, 19, 0) < 0) {
+    /* In kernels before 4.19 the frequency is updated only on internal ticks
+       (CONFIG_HZ).  As their rate cannot be reliably detected from the user
+       space, and it may not even be constant (CONFIG_NO_HZ - aka tickless),
+       assume the lowest commonly used constant rate */
+    tick_update_hz = 100;
+  }
+
+  /* ADJ_SETOFFSET support */
+  if (kernelvercmp(major, minor, patch, 2, 6, 39) < 0) {
+    have_setoffset = 0;
+  } else {
+    have_setoffset = 1;
+  }
+
+  DEBUG_LOG("hz=%d nominal_tick=%d max_tick_bias=%d tick_update_hz=%d",
+            hz, nominal_tick, max_tick_bias, tick_update_hz);
+}
+
+/* ================================================== */
+
+static void
+reset_adjtime_offset(void)
+{
+  struct timex txc;
+
+  /* Reset adjtime() offset */
+  txc.modes = ADJ_OFFSET_SINGLESHOT;
+  txc.offset = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+}
+
+/* ================================================== */
+
+static int
+test_step_offset(void)
+{
+  struct timex txc;
+
+  /* Zero maxerror and check it's reset to a maximum after ADJ_SETOFFSET.
+     This seems to be the only way how to verify that the kernel really
+     supports the ADJ_SETOFFSET mode as it doesn't return an error on unknown
+     mode. */
+
+  txc.modes = MOD_MAXERROR;
+  txc.maxerror = 0;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0 || txc.maxerror != 0)
+    return 0;
+
+  txc.modes = ADJ_SETOFFSET | ADJ_NANO;
+  txc.time.tv_sec = 0;
+  txc.time.tv_usec = 0;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0 || txc.maxerror < 100000)
+    return 0;
+
+  return 1;
+}
+
+/* ================================================== */
+
+static void
+report_time_adjust_blockers(void)
+{
+#if defined(FEAT_PRIVDROP) && defined(CAP_IS_SUPPORTED)
+  if (CAP_IS_SUPPORTED(CAP_SYS_TIME) && cap_get_bound(CAP_SYS_TIME))
+    return;
+  LOG(LOGS_WARN, "CAP_SYS_TIME not present");
+#endif
+}
+
+/* ================================================== */
+/* Initialisation code for this module */
+
+void
+SYS_Linux_Initialise(void)
+{
+  get_version_specific_details();
+
+  report_time_adjust_blockers();
+
+  reset_adjtime_offset();
+
+  if (have_setoffset && !test_step_offset()) {
+    LOG(LOGS_INFO, "adjtimex() doesn't support ADJ_SETOFFSET");
+    have_setoffset = 0;
+  }
+
+  SYS_Timex_InitialiseWithFunctions(1.0e6 * max_tick_bias / nominal_tick,
+                                    1.0 / tick_update_hz,
+                                    read_frequency, set_frequency,
+                                    have_setoffset ? apply_step_offset : NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+/* Finalisation code for this module */
+
+void
+SYS_Linux_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_Linux_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control)
+{
+  char cap_text[256];
+  cap_t cap;
+
+  if (prctl(PR_SET_KEEPCAPS, 1)) {
+    LOG_FATAL("prctl() failed");
+  }
+  
+  UTI_DropRoot(uid, gid);
+
+  /* Keep CAP_NET_BIND_SERVICE if the NTP server sockets may need to be bound
+     to a privileged port.
+     Keep CAP_NET_RAW if an NTP socket may need to be bound to a device on
+     kernels before 5.7.
+     Keep CAP_SYS_TIME if the clock control is enabled. */
+  if (snprintf(cap_text, sizeof (cap_text), "%s %s %s",
+               (CNF_GetNTPPort() > 0 && CNF_GetNTPPort() < 1024) ?
+                 "cap_net_bind_service=ep" : "",
+               (CNF_GetBindNtpInterface() || CNF_GetBindAcquisitionInterface()) &&
+                 !SYS_Linux_CheckKernelVersion(5, 7) ? "cap_net_raw=ep" : "",
+               clock_control ? "cap_sys_time=ep" : "") >= sizeof (cap_text))
+    assert(0);
+
+  /* Helpers don't need any capabilities */
+  if (context != SYS_MAIN_PROCESS)
+    cap_text[0] = '\0';
+
+  if ((cap = cap_from_text(cap_text)) == NULL) {
+    LOG_FATAL("cap_from_text() failed");
+  }
+
+  if (cap_set_proc(cap)) {
+    LOG_FATAL("cap_set_proc() failed");
+  }
+
+  cap_free(cap);
+}
+#endif
+
+/* ================================================== */
+
+#ifdef FEAT_SCFILTER
+static
+void check_seccomp_applicability(void)
+{
+  int mail_enabled;
+  double mail_threshold;
+  char *mail_user;
+
+  CNF_GetMailOnChange(&mail_enabled, &mail_threshold, &mail_user);
+  if (mail_enabled)
+    LOG_FATAL("mailonchange directive cannot be used with -F enabled");
+}
+
+/* ================================================== */
+
+void
+SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context)
+{
+  const int allowed[] = {
+    /* Clock */
+    SCMP_SYS(adjtimex),
+    SCMP_SYS(clock_adjtime),
+#ifdef __NR_clock_adjtime64
+    SCMP_SYS(clock_adjtime64),
+#endif
+    SCMP_SYS(clock_gettime),
+#ifdef __NR_clock_gettime64
+    SCMP_SYS(clock_gettime64),
+#endif
+    SCMP_SYS(gettimeofday),
+    SCMP_SYS(settimeofday),
+    SCMP_SYS(time),
+
+    /* Process */
+    SCMP_SYS(clone),
+#ifdef __NR_clone3
+    SCMP_SYS(clone3),
+#endif
+    SCMP_SYS(exit),
+    SCMP_SYS(exit_group),
+    SCMP_SYS(getpid),
+    SCMP_SYS(getrlimit),
+    SCMP_SYS(getuid),
+    SCMP_SYS(getuid32),
+#ifdef __NR_membarrier
+    SCMP_SYS(membarrier),
+#endif
+#ifdef __NR_rseq
+    SCMP_SYS(rseq),
+#endif
+    SCMP_SYS(rt_sigaction),
+    SCMP_SYS(rt_sigreturn),
+    SCMP_SYS(rt_sigprocmask),
+    SCMP_SYS(set_tid_address),
+    SCMP_SYS(sigreturn),
+    SCMP_SYS(wait4),
+    SCMP_SYS(waitpid),
+
+    /* Memory */
+    SCMP_SYS(brk),
+    SCMP_SYS(madvise),
+    SCMP_SYS(mmap),
+    SCMP_SYS(mmap2),
+    SCMP_SYS(mprotect),
+    SCMP_SYS(mremap),
+    SCMP_SYS(munmap),
+    SCMP_SYS(shmdt),
+
+    /* Filesystem */
+    SCMP_SYS(_llseek),
+    SCMP_SYS(access),
+    SCMP_SYS(chmod),
+    SCMP_SYS(chown),
+    SCMP_SYS(chown32),
+    SCMP_SYS(faccessat),
+    SCMP_SYS(fchmodat),
+    SCMP_SYS(fchownat),
+    SCMP_SYS(fstat),
+    SCMP_SYS(fstat64),
+    SCMP_SYS(fstatat64),
+    SCMP_SYS(getdents),
+    SCMP_SYS(getdents64),
+    SCMP_SYS(lseek),
+    SCMP_SYS(lstat),
+    SCMP_SYS(lstat64),
+    SCMP_SYS(newfstatat),
+    SCMP_SYS(readlink),
+    SCMP_SYS(readlinkat),
+    SCMP_SYS(rename),
+    SCMP_SYS(renameat),
+#ifdef __NR_renameat2
+    SCMP_SYS(renameat2),
+#endif
+    SCMP_SYS(stat),
+    SCMP_SYS(stat64),
+    SCMP_SYS(statfs),
+    SCMP_SYS(statfs64),
+#ifdef __NR_statx
+    SCMP_SYS(statx),
+#endif
+    SCMP_SYS(unlink),
+    SCMP_SYS(unlinkat),
+
+    /* Socket */
+    SCMP_SYS(accept),
+    SCMP_SYS(bind),
+    SCMP_SYS(connect),
+    SCMP_SYS(getsockname),
+    SCMP_SYS(getsockopt),
+    SCMP_SYS(recv),
+    SCMP_SYS(recvfrom),
+    SCMP_SYS(recvmmsg),
+#ifdef __NR_recvmmsg_time64
+    SCMP_SYS(recvmmsg_time64),
+#endif
+    SCMP_SYS(recvmsg),
+    SCMP_SYS(send),
+    SCMP_SYS(sendmmsg),
+    SCMP_SYS(sendmsg),
+    SCMP_SYS(sendto),
+    SCMP_SYS(shutdown),
+    /* TODO: check socketcall arguments */
+    SCMP_SYS(socketcall),
+
+    /* General I/O */
+    SCMP_SYS(_newselect),
+    SCMP_SYS(close),
+    SCMP_SYS(open),
+    SCMP_SYS(openat),
+    SCMP_SYS(pipe),
+    SCMP_SYS(pipe2),
+    SCMP_SYS(poll),
+    SCMP_SYS(ppoll),
+#ifdef __NR_ppoll_time64
+    SCMP_SYS(ppoll_time64),
+#endif
+    SCMP_SYS(pread64),
+    SCMP_SYS(pselect6),
+#ifdef __NR_pselect6_time64
+    SCMP_SYS(pselect6_time64),
+#endif
+    SCMP_SYS(read),
+    SCMP_SYS(futex),
+#ifdef __NR_futex_time64
+    SCMP_SYS(futex_time64),
+#endif
+    SCMP_SYS(select),
+    SCMP_SYS(set_robust_list),
+    SCMP_SYS(write),
+    SCMP_SYS(writev),
+
+    /* Miscellaneous */
+    SCMP_SYS(getrandom),
+    SCMP_SYS(sysinfo),
+    SCMP_SYS(uname),
+  };
+
+  const int denied_any[] = {
+    SCMP_SYS(execve),
+#ifdef __NR_execveat
+    SCMP_SYS(execveat),
+#endif
+    SCMP_SYS(fork),
+    SCMP_SYS(ptrace),
+    SCMP_SYS(vfork),
+  };
+
+  const int denied_ntske[] = {
+    SCMP_SYS(ioctl),
+    SCMP_SYS(setsockopt),
+    SCMP_SYS(socket),
+  };
+
+  const int socket_domains[] = {
+    AF_NETLINK, AF_UNIX, AF_INET,
+#ifdef FEAT_IPV6
+    AF_INET6,
+#endif
+  };
+
+  const static int socket_options[][2] = {
+    { SOL_IP, IP_PKTINFO }, { SOL_IP, IP_FREEBIND }, { SOL_IP, IP_TOS },
+#ifdef FEAT_IPV6
+    { SOL_IPV6, IPV6_V6ONLY }, { SOL_IPV6, IPV6_RECVPKTINFO },
+#ifdef IPV6_TCLASS
+    { SOL_IPV6, IPV6_TCLASS },
+#endif
+#endif
+#ifdef SO_BINDTODEVICE
+    { SOL_SOCKET, SO_BINDTODEVICE },
+#endif
+    { SOL_SOCKET, SO_BROADCAST }, { SOL_SOCKET, SO_REUSEADDR },
+#ifdef SO_REUSEPORT
+    { SOL_SOCKET, SO_REUSEPORT },
+#endif
+    { SOL_SOCKET, SO_TIMESTAMP }, { SOL_SOCKET, SO_TIMESTAMPNS },
+#ifdef HAVE_LINUX_TIMESTAMPING
+    { SOL_SOCKET, SO_SELECT_ERR_QUEUE }, { SOL_SOCKET, SO_TIMESTAMPING },
+#endif
+  };
+
+  const static int fcntls[] = { F_GETFD, F_SETFD, F_GETFL, F_SETFL };
+
+  const static unsigned long ioctls[] = {
+    FIONREAD, TCGETS, TIOCGWINSZ,
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+    PTP_EXTTS_REQUEST, PTP_SYS_OFFSET,
+#ifdef PTP_PIN_SETFUNC
+    PTP_PIN_SETFUNC,
+#endif
+#ifdef PTP_SYS_OFFSET_EXTENDED
+    PTP_SYS_OFFSET_EXTENDED,
+#endif
+#ifdef PTP_SYS_OFFSET_PRECISE
+    PTP_SYS_OFFSET_PRECISE,
+#endif
+#endif
+#ifdef FEAT_PPS
+    PPS_FETCH,
+#endif
+#ifdef FEAT_RTC
+    RTC_RD_TIME, RTC_SET_TIME, RTC_UIE_ON, RTC_UIE_OFF,
+#endif
+#ifdef HAVE_LINUX_TIMESTAMPING
+    SIOCETHTOOL,
+#endif
+  };
+
+  unsigned int default_action, deny_action;
+  scmp_filter_ctx *ctx;
+  int i;
+
+  /* Sign of the level determines the deny action (kill or SIGSYS).
+     At level 1, selected syscalls are allowed, others are denied.
+     At level 2, selected syscalls are denied, others are allowed. */
+
+  deny_action = level > 0 ? SCMP_ACT_KILL : SCMP_ACT_TRAP;
+  if (level < 0)
+    level = -level;
+
+  switch (level) {
+    case 1:
+      default_action = deny_action;
+      break;
+    case 2:
+      default_action = SCMP_ACT_ALLOW;
+      break;
+    default:
+      LOG_FATAL("Unsupported filter level");
+  }
+
+  if (context == SYS_MAIN_PROCESS) {
+    /* Check if the chronyd configuration is supported */
+    check_seccomp_applicability();
+
+    /* At level 1, start a helper process which will not have a seccomp filter.
+       It will be used for getaddrinfo(), for which it is difficult to maintain
+       a list of required system calls (with glibc it depends on what NSS
+       modules are installed and enabled on the system). */
+    if (default_action != SCMP_ACT_ALLOW)
+      PRV_StartHelper();
+  }
+
+  ctx = seccomp_init(default_action);
+  if (ctx == NULL)
+      LOG_FATAL("Failed to initialize seccomp");
+
+  if (default_action != SCMP_ACT_ALLOW) {
+    for (i = 0; i < sizeof (allowed) / sizeof (*allowed); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, allowed[i], 0) < 0)
+        goto add_failed;
+    }
+  } else {
+    for (i = 0; i < sizeof (denied_any) / sizeof (*denied_any); i++) {
+      if (seccomp_rule_add(ctx, deny_action, denied_any[i], 0) < 0)
+        goto add_failed;
+    }
+
+    if (context == SYS_NTSKE_HELPER) {
+      for (i = 0; i < sizeof (denied_ntske) / sizeof (*denied_ntske); i++) {
+        if (seccomp_rule_add(ctx, deny_action, denied_ntske[i], 0) < 0)
+          goto add_failed;
+      }
+    }
+  }
+
+  if (default_action != SCMP_ACT_ALLOW && context == SYS_MAIN_PROCESS) {
+    /* Allow opening sockets in selected domains */
+    for (i = 0; i < sizeof (socket_domains) / sizeof (*socket_domains); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
+                           SCMP_A0(SCMP_CMP_EQ, socket_domains[i])) < 0)
+        goto add_failed;
+    }
+
+    /* Allow selected socket options */
+    for (i = 0; i < sizeof (socket_options) / sizeof (*socket_options); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), 2,
+                           SCMP_A1(SCMP_CMP_EQ, socket_options[i][0]),
+                           SCMP_A2(SCMP_CMP_EQ, socket_options[i][1])))
+        goto add_failed;
+    }
+
+    /* Allow selected fcntl calls */
+    for (i = 0; i < sizeof (fcntls) / sizeof (*fcntls); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl), 1,
+                           SCMP_A1(SCMP_CMP_EQ, fcntls[i])) < 0 ||
+          seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), 1,
+                           SCMP_A1(SCMP_CMP_EQ, fcntls[i])) < 0)
+        goto add_failed;
+    }
+
+    /* Allow selected ioctls */
+    for (i = 0; i < sizeof (ioctls) / sizeof (*ioctls); i++) {
+      if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(ioctl), 1,
+                           SCMP_A1(SCMP_CMP_EQ, ioctls[i])) < 0)
+        goto add_failed;
+    }
+  }
+
+  if (seccomp_load(ctx) < 0)
+    LOG_FATAL("Failed to load seccomp rules");
+
+  LOG(context == SYS_MAIN_PROCESS ? LOGS_INFO : LOGS_DEBUG,
+      "Loaded seccomp filter (level %d)", level);
+  seccomp_release(ctx);
+  return;
+
+add_failed:
+  LOG_FATAL("Failed to add seccomp rules");
+}
+#endif
+
+/* ================================================== */
+
+int
+SYS_Linux_CheckKernelVersion(int req_major, int req_minor)
+{
+  int major, minor, patch;
+
+  get_kernel_version(&major, &minor, &patch);
+
+  return kernelvercmp(req_major, req_minor, 0, major, minor, patch) <= 0;
+}
+
+/* ================================================== */
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+
+static int
+get_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+  struct ptp_sys_offset sys_off;
+  int i;
+
+  max_samples = CLAMP(0, max_samples, PTP_MAX_SAMPLES);
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  sys_off.n_samples = max_samples;
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET", strerror(errno));
+    return 0;
+  }
+
+  for (i = 0; i < max_samples; i++) {
+    ts[i][0].tv_sec = sys_off.ts[i * 2].sec;
+    ts[i][0].tv_nsec = sys_off.ts[i * 2].nsec;
+    ts[i][1].tv_sec = sys_off.ts[i * 2 + 1].sec;
+    ts[i][1].tv_nsec = sys_off.ts[i * 2 + 1].nsec;
+    ts[i][2].tv_sec = sys_off.ts[i * 2 + 2].sec;
+    ts[i][2].tv_nsec = sys_off.ts[i * 2 + 2].nsec;
+  }
+
+  return max_samples;
+}
+
+/* ================================================== */
+
+static int
+get_extended_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+#ifdef PTP_SYS_OFFSET_EXTENDED
+  struct ptp_sys_offset_extended sys_off;
+  int i;
+
+  max_samples = CLAMP(0, max_samples, PTP_MAX_SAMPLES);
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  sys_off.n_samples = max_samples;
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET_EXTENDED, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET_EXTENDED", strerror(errno));
+    return 0;
+  }
+
+  for (i = 0; i < max_samples; i++) {
+    ts[i][0].tv_sec = sys_off.ts[i][0].sec;
+    ts[i][0].tv_nsec = sys_off.ts[i][0].nsec;
+    ts[i][1].tv_sec = sys_off.ts[i][1].sec;
+    ts[i][1].tv_nsec = sys_off.ts[i][1].nsec;
+    ts[i][2].tv_sec = sys_off.ts[i][2].sec;
+    ts[i][2].tv_nsec = sys_off.ts[i][2].nsec;
+  }
+
+  return max_samples;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+static int
+get_precise_phc_readings(int phc_fd, int max_samples, struct timespec ts[][3])
+{
+#ifdef PTP_SYS_OFFSET_PRECISE
+  struct ptp_sys_offset_precise sys_off;
+
+  if (max_samples < 1)
+    return 0;
+
+  /* Silence valgrind */
+  memset(&sys_off, 0, sizeof (sys_off));
+
+  if (ioctl(phc_fd, PTP_SYS_OFFSET_PRECISE, &sys_off)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_SYS_OFFSET_PRECISE",
+              strerror(errno));
+    return 0;
+  }
+
+  ts[0][0].tv_sec = sys_off.sys_realtime.sec;
+  ts[0][0].tv_nsec = sys_off.sys_realtime.nsec;
+  ts[0][1].tv_sec = sys_off.device.sec;
+  ts[0][1].tv_nsec = sys_off.device.nsec;
+  ts[0][2] = ts[0][0];
+
+  return 1;
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_OpenPHC(const char *path, int phc_index)
+{
+  struct ptp_clock_caps caps;
+  char phc_path[64];
+  int phc_fd;
+
+  if (!path) {
+    if (snprintf(phc_path, sizeof (phc_path), "/dev/ptp%d", phc_index) >= sizeof (phc_path))
+      return -1;
+    path = phc_path;
+  }
+
+  phc_fd = open(path, O_RDONLY);
+  if (phc_fd < 0) {
+    LOG(LOGS_ERR, "Could not open %s : %s", path, strerror(errno));
+    return -1;
+  }
+
+  /* Make sure it is a PHC */
+  if (ioctl(phc_fd, PTP_CLOCK_GETCAPS, &caps)) {
+    LOG(LOGS_ERR, "ioctl(%s) failed : %s", "PTP_CLOCK_GETCAPS", strerror(errno));
+    close(phc_fd);
+    return -1;
+  }
+
+  UTI_FdSetCloexec(phc_fd);
+
+  return phc_fd;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_GetPHCReadings(int fd, int nocrossts, int *reading_mode, int max_readings,
+                         struct timespec tss[][3])
+{
+  int r = 0;
+
+  if ((*reading_mode == 2 || *reading_mode == 0) && !nocrossts &&
+      (r = get_precise_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 2;
+  } else if ((*reading_mode == 3 || *reading_mode == 0) &&
+             (r = get_extended_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 3;
+  } else if ((*reading_mode == 1 || *reading_mode == 0) &&
+             (r = get_phc_readings(fd, max_readings, tss)) > 0) {
+    *reading_mode = 1;
+  }
+
+  return r;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_SetPHCExtTimestamping(int fd, int pin, int channel,
+                                int rising, int falling, int enable)
+{
+  struct ptp_extts_request extts_req;
+#ifdef PTP_PIN_SETFUNC
+  struct ptp_pin_desc pin_desc;
+
+  memset(&pin_desc, 0, sizeof (pin_desc));
+  pin_desc.index = pin;
+  pin_desc.func = enable ? PTP_PF_EXTTS : PTP_PF_NONE;
+  pin_desc.chan = channel;
+
+  if (pin >= 0 && ioctl(fd, PTP_PIN_SETFUNC, &pin_desc)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_PIN_SETFUNC", strerror(errno));
+    return 0;
+  }
+#else
+  DEBUG_LOG("Missing PTP_PIN_SETFUNC");
+  return 0;
+#endif
+
+  memset(&extts_req, 0, sizeof (extts_req));
+  extts_req.index = channel;
+  extts_req.flags = (enable ? PTP_ENABLE_FEATURE : 0) |
+                    (rising ? PTP_RISING_EDGE : 0) |
+                    (falling ? PTP_FALLING_EDGE : 0);
+
+  if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_req)) {
+    DEBUG_LOG("ioctl(%s) failed : %s", "PTP_EXTTS_REQUEST", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SYS_Linux_ReadPHCExtTimestamp(int fd, struct timespec *phc_ts, int *channel)
+{
+  struct ptp_extts_event extts_event;
+  struct pollfd pfd;
+
+  /* Make sure the read will not block in case we have multiple
+     descriptors of the same PHC (O_NONBLOCK does not work) */
+  pfd.fd = fd;
+  pfd.events = POLLIN;
+  if (poll(&pfd, 1, 0) != 1 || pfd.revents != POLLIN) {
+    DEBUG_LOG("Missing PHC extts event");
+    return 0;
+  }
+
+  if (read(fd, &extts_event, sizeof (extts_event)) != sizeof (extts_event)) {
+    DEBUG_LOG("Could not read PHC extts event");
+    return 0;
+  }
+
+  phc_ts->tv_sec = extts_event.t.sec;
+  phc_ts->tv_nsec = extts_event.t.nsec;
+  *channel = extts_event.index;
+
+  return 1;
+}
+
+#endif
diff --git a/sys_linux.h b/sys_linux.h
new file mode 100644
index 0000000..4741624
--- /dev/null
+++ b/sys_linux.h
@@ -0,0 +1,52 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  The header file for the linux driver
+  */
+
+#ifndef GOT_SYS_LINUX_H
+#define GOT_SYS_LINUX_H
+
+#include "sys.h"
+
+extern void SYS_Linux_Initialise(void);
+
+extern void SYS_Linux_Finalise(void);
+
+extern void SYS_Linux_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control);
+
+extern void SYS_Linux_EnableSystemCallFilter(int level, SYS_ProcessContext context);
+
+extern int SYS_Linux_CheckKernelVersion(int req_major, int req_minor);
+
+extern int SYS_Linux_OpenPHC(const char *path, int phc_index);
+
+extern int SYS_Linux_GetPHCReadings(int fd, int nocrossts, int *reading_mode, int max_readings,
+                                    struct timespec tss[][3]);
+
+extern int SYS_Linux_SetPHCExtTimestamping(int fd, int pin, int channel,
+                                           int rising, int falling, int enable);
+
+extern int SYS_Linux_ReadPHCExtTimestamp(int fd, struct timespec *phc_ts, int *channel);
+
+#endif  /* GOT_SYS_LINUX_H */
diff --git a/sys_macosx.c b/sys_macosx.c
new file mode 100644
index 0000000..e3a38ed
--- /dev/null
+++ b/sys_macosx.c
@@ -0,0 +1,516 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Bryan Christianson  2015, 2017, 2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for the macOS operating system.
+
+  */
+
+#include "config.h"
+
+#ifdef MACOSX
+
+#include "sysincl.h"
+
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <pthread.h>
+
+#include "sys_macosx.h"
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "sched.h"
+#include "privops.h"
+#include "util.h"
+
+#include <dlfcn.h>
+
+#ifdef HAVE_MACOS_SYS_TIMEX
+#include "sys_netbsd.h"
+
+static int have_ntp_adjtime = 0;
+#endif
+
+/* ================================================== */
+
+/* This register contains the number of seconds by which the local
+   clock was estimated to be fast of reference time at the epoch when
+   LCL_ReadRawTime() returned T0 */
+
+static double offset_register;
+
+/* This register contains the epoch to which the offset is referenced */
+
+static struct timespec T0;
+
+/* This register contains the current estimate of the system
+   frequency, in absolute (NOT ppm) */
+
+static double current_freq;
+
+/* This register contains the number of seconds of adjustment that
+   were passed to adjtime last time it was called. */
+
+static double adjustment_requested;
+
+/* Interval in seconds between adjustments to cancel systematic drift */
+
+#define DRIFT_REMOVAL_INTERVAL (4.0)
+#define DRIFT_REMOVAL_INTERVAL_MIN (0.5)
+
+/* If current_drift_removal_interval / drift_removal_interval exceeds this
+   ratio, then restart the drift removal timer */
+
+#define DRIFT_REMOVAL_RESTART_RATIO (8.0)
+
+static double drift_removal_interval;
+static double current_drift_removal_interval;
+static struct timespec Tdrift;
+
+/* weighting applied to error in calculating drift_removal_interval */
+#define ERROR_WEIGHT (0.5)
+
+/* minimum resolution of current_frequency */
+#define FREQUENCY_RES (1.0e-9)
+
+#define NANOS_PER_MSEC (1000000ULL)
+
+/* RTC synchronisation - once an hour */
+
+static struct timespec last_rtc_sync;
+#define RTC_SYNC_INTERVAL (60 * 60.0)
+
+/* ================================================== */
+
+static void
+clock_initialise(void)
+{
+  struct timeval newadj, oldadj;
+
+  offset_register = 0.0;
+  adjustment_requested = 0.0;
+  current_freq = 0.0;
+  drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+  current_drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+
+  LCL_ReadRawTime(&T0);
+  Tdrift = T0;
+  last_rtc_sync = T0;
+
+  newadj.tv_sec = 0;
+  newadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+}
+
+/* ================================================== */
+
+static void
+clock_finalise(void)
+{
+  /* Nothing to do yet */
+}
+
+/* ================================================== */
+
+static void
+start_adjust(void)
+{
+  struct timeval newadj, oldadj;
+  struct timespec T1;
+  double elapsed, accrued_error, predicted_error, drift_removal_elapsed;
+  double adjust_required;
+  double rounding_error;
+  double old_adjust_remaining;
+
+  /* Determine the amount of error built up since the last adjustment */
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  accrued_error = elapsed * current_freq;
+
+  drift_removal_elapsed = UTI_DiffTimespecsToDouble(&T1, &Tdrift);
+
+  /* To allow for the clock being stepped either forward or backwards, clamp
+     the elapsed time to bounds [ 0.0, current_drift_removal_interval ] */
+  drift_removal_elapsed = MIN(MAX(0.0, drift_removal_elapsed), current_drift_removal_interval);
+
+  predicted_error = (current_drift_removal_interval - drift_removal_elapsed) / 2.0 * current_freq;
+
+  DEBUG_LOG("drift_removal_elapsed: %.3f current_drift_removal_interval: %.3f predicted_error: %.3f",
+            1.0e6 * drift_removal_elapsed, 1.0e6 * current_drift_removal_interval,
+            1.0e6 * predicted_error);
+
+  adjust_required = - (accrued_error + offset_register + predicted_error);
+
+  UTI_DoubleToTimeval(adjust_required, &newadj);
+  adjustment_requested = UTI_TimevalToDouble(&newadj);
+  rounding_error = adjust_required - adjustment_requested;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  old_adjust_remaining = UTI_TimevalToDouble(&oldadj);
+
+  offset_register = rounding_error - old_adjust_remaining - predicted_error;
+
+  T0 = T1;
+}
+
+/* ================================================== */
+
+static void
+stop_adjust(void)
+{
+  struct timespec T1;
+  struct timeval zeroadj, remadj;
+  double adjustment_remaining, adjustment_achieved;
+  double elapsed, elapsed_plus_adjust;
+
+  zeroadj.tv_sec = 0;
+  zeroadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&zeroadj, &remadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  adjustment_remaining = UTI_TimevalToDouble(&remadj);
+
+  adjustment_achieved = adjustment_requested - adjustment_remaining;
+  elapsed_plus_adjust = elapsed - adjustment_achieved;
+
+  offset_register += current_freq * elapsed_plus_adjust - adjustment_remaining;
+
+  adjustment_requested = 0.0;
+  T0 = T1;
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   slew backwards */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  stop_adjust();
+  offset_register += offset;
+  start_adjust();
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   step backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timespec old_time, new_time, T1;
+  struct timeval new_time_tv;
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&old_time);
+
+  UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
+  UTI_TimespecToTimeval(&new_time, &new_time_tv);
+
+  if (PRV_SetTime(&new_time_tv, NULL) < 0) {
+    DEBUG_LOG("settimeofday() failed");
+    return 0;
+  }
+
+  UTI_AddDoubleToTimespec(&T0, -offset, &T1);
+  T0 = T1;
+
+  start_adjust();
+
+  return 1;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double new_freq_ppm)
+{
+  stop_adjust();
+  current_freq = new_freq_ppm * 1.0e-6;
+  start_adjust();
+
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static void
+get_offset_correction(struct timespec *raw,
+                      double *corr, double *err)
+{
+  stop_adjust();
+  *corr = -offset_register;
+  start_adjust();
+  if (err)
+    *err = 0.0;
+}
+
+/* ================================================== */
+
+/* Cancel systematic drift */
+
+static SCH_TimeoutID drift_removal_id;
+
+/* ================================================== */
+/* This is the timer callback routine which is called periodically to
+ invoke a time adjustment to take out the machine's drift.
+ Otherwise, times reported through this software (e.g. by running
+ ntpdate from another machine) show the machine being correct (since
+ they correct for drift build-up), but any program on this machine
+ that reads the system time will be given an erroneous value, the
+ degree of error depending on how long it is since
+ get_offset_correction was last called. */
+
+static void
+drift_removal_timeout(SCH_ArbitraryArgument not_used)
+{
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&Tdrift);
+
+  current_drift_removal_interval = drift_removal_interval;
+
+  start_adjust();
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+/* use est_error to calculate the drift_removal_interval and
+   update the RTC */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double interval;
+
+  if (!synchronised) {
+    drift_removal_interval = MAX(drift_removal_interval, DRIFT_REMOVAL_INTERVAL);
+  } else {
+    if (CNF_GetRtcSync()) {
+      struct timespec now;
+      double rtc_sync_elapsed;
+
+      SCH_GetLastEventTime(NULL, NULL, &now);
+      rtc_sync_elapsed = UTI_DiffTimespecsToDouble(&now, &last_rtc_sync);
+      if (fabs(rtc_sync_elapsed) >= RTC_SYNC_INTERVAL) {
+        /* update the RTC by applying a step of 0.0 secs */
+        apply_step_offset(0.0);
+        last_rtc_sync = now;
+        DEBUG_LOG("rtc synchronised");
+      }
+    }
+
+    interval = ERROR_WEIGHT * est_error / (fabs(current_freq) + FREQUENCY_RES);
+    drift_removal_interval = MAX(interval, DRIFT_REMOVAL_INTERVAL_MIN);
+
+    DEBUG_LOG("est_error: %.3f current_freq: %.3f est drift_removal_interval: %.3f act drift_removal_interval: %.3f",
+                est_error * 1.0e6, current_freq * 1.0e6, interval, drift_removal_interval);
+  }
+
+  if (current_drift_removal_interval / drift_removal_interval > DRIFT_REMOVAL_RESTART_RATIO) {
+    /* recover from a large est_error by resetting the timer */
+    SCH_ArbitraryArgument unused;
+    SCH_RemoveTimeout(drift_removal_id);
+    unused = NULL;
+    drift_removal_timeout(unused);
+  }
+}
+
+/* ================================================== */
+/*
+  Give chronyd real time priority so that time critical calculations
+  are not pre-empted by the kernel.
+*/
+
+static int
+set_realtime(void)
+{
+  /* https://developer.apple.com/library/ios/technotes/tn2169/_index.html */
+
+  mach_timebase_info_data_t timebase_info;
+  double clock2abs;
+  thread_time_constraint_policy_data_t policy;
+  int kr;
+
+  mach_timebase_info(&timebase_info);
+  clock2abs = ((double)timebase_info.denom / (double)timebase_info.numer) * NANOS_PER_MSEC;
+
+  policy.period = 0;
+  policy.computation = (uint32_t)(5 * clock2abs); /* 5 ms of work */
+  policy.constraint = (uint32_t)(10 * clock2abs);
+  policy.preemptible = 0;
+
+  kr = thread_policy_set(
+          pthread_mach_thread_np(pthread_self()),
+          THREAD_TIME_CONSTRAINT_POLICY,
+          (thread_policy_t)&policy,
+          THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+
+  if (kr != KERN_SUCCESS) {
+    LOG(LOGS_WARN, "Cannot set real-time priority: %d", kr);
+    return -1;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_SetScheduler(int SchedPriority)
+{
+  if (SchedPriority) {
+    set_realtime();
+  }
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void SYS_MacOSX_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+
+  UTI_DropRoot(uid, gid);
+}
+#endif
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Initialise(void)
+{
+  clock_initialise();
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency,
+                            accrue_offset, apply_step_offset,
+                            get_offset_correction,
+                            NULL /* set_leap */,
+                            set_sync_status);
+
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Finalise(void)
+{
+  SCH_RemoveTimeout(drift_removal_id);
+
+  clock_finalise();
+}
+
+/* ================================================== */
+
+#if HAVE_CLOCK_GETTIME
+int
+clock_gettime(clockid_t clock_id, struct timespec *ts)
+{
+  /* Check that the system clock_gettime symbol is actually present before
+     attempting to call it. The symbol is available in macOS 10.12
+     and later. */
+
+  static int init = 0;
+  static int (*sys_clock_gettime)(clockid_t, struct timespec *) = NULL;
+  int ret = 0;
+
+  if (!init) {
+    sys_clock_gettime = dlsym(RTLD_NEXT, "clock_gettime");
+    init = 1;
+  }
+
+  if (sys_clock_gettime != NULL) {
+    ret = sys_clock_gettime(clock_id, ts);
+  } else {
+    struct timeval tv;
+
+    if (gettimeofday(&tv, NULL) < 0)
+      LOG_FATAL("gettimeofday() failed : %s", strerror(errno));
+
+    UTI_TimevalToTimespec(&tv, ts);
+  }
+  return ret;
+}
+#endif
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Initialise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  have_ntp_adjtime = (dlsym(RTLD_NEXT, "ntp_adjtime") != NULL);
+  if (have_ntp_adjtime) {
+    SYS_NetBSD_Initialise();
+    return;
+  }
+#endif
+  legacy_MacOSX_Initialise();
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Finalise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  if (have_ntp_adjtime) {
+    SYS_NetBSD_Finalise();
+    return;
+  }
+#endif
+  legacy_MacOSX_Finalise();
+}
+
+#endif
diff --git a/sys_macosx.h b/sys_macosx.h
new file mode 100644
index 0000000..09f0beb
--- /dev/null
+++ b/sys_macosx.h
@@ -0,0 +1,40 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Bryan Christianson 2015
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for macOS driver
+
+  */
+
+#ifndef GOT_SYS_MACOSX_H
+#define GOT_SYS_MACOSX_H
+
+#include "sys.h"
+
+void SYS_MacOSX_SetScheduler(int SchedPriority);
+void SYS_MacOSX_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+void SYS_MacOSX_Initialise(void);
+void SYS_MacOSX_Finalise(void);
+
+#endif
diff --git a/sys_netbsd.c b/sys_netbsd.c
new file mode 100644
index 0000000..e1b99bb
--- /dev/null
+++ b/sys_netbsd.c
@@ -0,0 +1,158 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for the NetBSD and FreeBSD operating system.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_netbsd.h"
+#include "sys_timex.h"
+#include "logging.h"
+#include "privops.h"
+#include "util.h"
+
+/* Maximum frequency offset accepted by the kernel (in ppm) */
+#define MAX_FREQ 500.0
+
+/* Minimum assumed rate at which the kernel updates the clock frequency */
+#define MIN_TICK_RATE 100
+
+/* Interval between kernel updates of the adjtime() offset */
+#define ADJTIME_UPDATE_INTERVAL 1.0
+
+/* Maximum adjtime() slew rate (in ppm) */
+#define MAX_ADJTIME_SLEWRATE 5000.0
+
+/* Minimum offset adjtime() slews faster than MAX_FREQ */
+#define MIN_FASTSLEW_OFFSET 1.0
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   slew backwards */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  struct timeval newadj, oldadj;
+  double doldadj;
+
+  UTI_DoubleToTimeval(-offset, &newadj);
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0)
+    LOG_FATAL("adjtime() failed");
+
+  /* Add the old remaining adjustment if not zero */
+  doldadj = UTI_TimevalToDouble(&oldadj);
+  if (doldadj != 0.0) {
+    UTI_DoubleToTimeval(-offset + doldadj, &newadj);
+    if (PRV_AdjustTime(&newadj, NULL) < 0)
+      LOG_FATAL("adjtime() failed");
+  }
+}
+
+/* ================================================== */
+
+static void
+get_offset_correction(struct timespec *raw,
+                      double *corr, double *err)
+{
+  struct timeval remadj;
+  double adjustment_remaining;
+#ifdef MACOSX
+  struct timeval tv = {0, 0};
+
+  if (PRV_AdjustTime(&tv, &remadj) < 0)
+    LOG_FATAL("adjtime() failed");
+
+  if (PRV_AdjustTime(&remadj, NULL) < 0)
+    LOG_FATAL("adjtime() failed");
+#else
+  if (PRV_AdjustTime(NULL, &remadj) < 0)
+    LOG_FATAL("adjtime() failed");
+#endif
+
+  adjustment_remaining = UTI_TimevalToDouble(&remadj);
+
+  *corr = adjustment_remaining;
+  if (err) {
+    if (*corr != 0.0)
+      *err = 1.0e-6 * MAX_ADJTIME_SLEWRATE / ADJTIME_UPDATE_INTERVAL;
+    else
+      *err = 0.0;
+  }
+}
+
+/* ================================================== */
+
+void
+SYS_NetBSD_Initialise(void)
+{
+  SYS_Timex_InitialiseWithFunctions(MAX_FREQ, 1.0 / MIN_TICK_RATE,
+                                    NULL, NULL, NULL,
+                                    MIN_FASTSLEW_OFFSET, MAX_ADJTIME_SLEWRATE,
+                                    accrue_offset, get_offset_correction);
+}
+
+/* ================================================== */
+
+void
+SYS_NetBSD_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_NetBSD_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control)
+{
+#ifdef NETBSD
+  int fd;
+#endif
+
+  /* On NetBSD the helper is used only for socket binding, but on FreeBSD
+     it's used also for setting and adjusting the system clock */
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+
+  UTI_DropRoot(uid, gid);
+
+#ifdef NETBSD
+  if (!clock_control)
+    return;
+
+  /* Check if we have write access to /dev/clockctl */
+  fd = open("/dev/clockctl", O_WRONLY);
+  if (fd < 0)
+    LOG_FATAL("Can't write to /dev/clockctl");
+  close(fd);
+#endif
+}
+#endif
diff --git a/sys_netbsd.h b/sys_netbsd.h
new file mode 100644
index 0000000..7a05e6c
--- /dev/null
+++ b/sys_netbsd.h
@@ -0,0 +1,39 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NetBSD driver
+  */
+
+#ifndef GOT_SYS_NETBSD_H
+#define GOT_SYS_NETBSD_H
+
+#include "sys.h"
+
+void SYS_NetBSD_Initialise(void);
+
+void SYS_NetBSD_Finalise(void);
+
+void SYS_NetBSD_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context, int clock_control);
+
+#endif
diff --git a/sys_null.c b/sys_null.c
new file mode 100644
index 0000000..3a0d5f6
--- /dev/null
+++ b/sys_null.c
@@ -0,0 +1,140 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Null clock driver for operation with no clock control.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "sys_null.h"
+
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "util.h"
+
+/* Current frequency offset of the system clock (in ppm) */
+static double freq;
+
+/* Offset of the system clock at the last update */
+static double offset_register;
+
+/* Time of the last update */
+static struct timespec last_update;
+
+/* Minimum interval between updates when frequency is constant */
+#define MIN_UPDATE_INTERVAL 1000.0
+
+/* ================================================== */
+
+static void
+update_offset(void)
+{
+  struct timespec now;
+  double duration;
+
+  LCL_ReadRawTime(&now);
+  duration = UTI_DiffTimespecsToDouble(&now, &last_update);
+  offset_register += 1.0e-6 * freq * duration;
+  last_update = now;
+
+  DEBUG_LOG("System clock offset=%e freq=%f", offset_register, freq);
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return freq;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  update_offset();
+  freq = freq_ppm;
+
+  return freq;
+}
+
+/* ================================================== */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  offset_register += offset;
+}
+
+/* ================================================== */
+
+static int
+apply_step_offset(double offset)
+{
+  return 0;
+}
+
+/* ================================================== */
+
+static void
+offset_convert(struct timespec *raw, double *corr, double *err)
+{
+  double duration;
+
+  duration = UTI_DiffTimespecsToDouble(raw, &last_update);
+
+  if (duration > MIN_UPDATE_INTERVAL) {
+    update_offset();
+    duration = 0.0;
+  }
+
+  *corr = -1.0e-6 * freq * duration - offset_register;
+
+  if (err)
+    *err = 0.0;
+}
+
+/* ================================================== */
+
+void
+SYS_Null_Initialise(void)
+{
+  offset_register = 0.0;
+  LCL_ReadRawTime(&last_update);
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency, accrue_offset,
+                            apply_step_offset, offset_convert, NULL, NULL);
+
+  LOG(LOGS_INFO, "Disabled control of system clock");
+}
+
+/* ================================================== */
+
+void
+SYS_Null_Finalise(void)
+{
+}
diff --git a/sys_null.h b/sys_null.h
new file mode 100644
index 0000000..0fbf077
--- /dev/null
+++ b/sys_null.h
@@ -0,0 +1,34 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for null clock driver
+  */
+
+#ifndef GOT_SYS_NULL_H
+#define GOT_SYS_NULL_H
+
+extern void SYS_Null_Initialise(void);
+
+extern void SYS_Null_Finalise(void);
+
+#endif
diff --git a/sys_posix.c b/sys_posix.c
new file mode 100644
index 0000000..356e86a
--- /dev/null
+++ b/sys_posix.c
@@ -0,0 +1,109 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  This module is for POSIX compliant operating systems.
+
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <sys/utsname.h>
+
+#if defined(HAVE_PTHREAD_SETSCHEDPARAM)
+#include <pthread.h>
+#include <sched.h>
+#endif
+
+#if defined(HAVE_MLOCKALL)
+#include <sys/mman.h>
+#endif
+#if defined(HAVE_SETRLIMIT_MEMLOCK)
+#include <sys/resource.h>
+#endif
+
+#include "sys_posix.h"
+#include "conf.h"
+#include "local.h"
+#include "logging.h"
+#include "util.h"
+
+/* ================================================== */
+
+#if defined(HAVE_PTHREAD_SETSCHEDPARAM)
+/* Install SCHED_FIFO real-time scheduler with specified priority */
+void
+SYS_Posix_SetScheduler(int priority)
+{
+  struct sched_param sched;
+  int pmax, pmin;
+
+  if (priority < 1 || priority > 99)
+    LOG_FATAL("Bad scheduler priority: %d", priority);
+
+  sched.sched_priority = priority;
+  pmax = sched_get_priority_max(SCHED_FIFO);
+  pmin = sched_get_priority_min(SCHED_FIFO);
+  if (priority > pmax) {
+    sched.sched_priority = pmax;
+  } else if (priority < pmin) {
+    sched.sched_priority = pmin;
+  }
+
+  if (pthread_setschedparam(pthread_self(), SCHED_FIFO, &sched) < 0) {
+    LOG(LOGS_ERR, "pthread_setschedparam() failed");
+  } else {
+    DEBUG_LOG("Enabled SCHED_FIFO with priority %d", sched.sched_priority);
+  }
+}
+#endif /* HAVE_PTHREAD_SETSCHEDPARAM  */
+
+/* ================================================== */
+
+#if defined(HAVE_MLOCKALL)
+/* Lock the process into RAM so that it will never be swapped out */
+void
+SYS_Posix_MemLockAll(void)
+{
+#if defined(HAVE_SETRLIMIT_MEMLOCK)
+  struct rlimit rlim;
+
+  /* Ensure we can reserve as much as we need */
+  rlim.rlim_max = RLIM_INFINITY;
+  rlim.rlim_cur = RLIM_INFINITY;
+  if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
+    LOG(LOGS_ERR, "setrlimit() failed");
+    return;
+  }
+#endif
+
+  if (mlockall(MCL_CURRENT|MCL_FUTURE) < 0) {
+    LOG(LOGS_ERR, "mlockall() failed");
+  } else {
+    DEBUG_LOG("Successfully locked into RAM");
+  }
+}
+#endif /* HAVE_MLOCKALL */
diff --git a/sys_posix.h b/sys_posix.h
new file mode 100644
index 0000000..bb34b80
--- /dev/null
+++ b/sys_posix.h
@@ -0,0 +1,36 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) John G. Hasler  2009
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2018
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  The header file for shared Posix functionality
+  */
+
+#ifndef GOT_SYS_POSIX_H
+#define GOT_SYS_POSIX_H
+
+extern void SYS_Posix_MemLockAll(void);
+
+extern void SYS_Posix_SetScheduler(int priority);
+
+#endif  /* GOT_SYS_POSIX_H */
diff --git a/sys_solaris.c b/sys_solaris.c
new file mode 100644
index 0000000..3210ef0
--- /dev/null
+++ b/sys_solaris.c
@@ -0,0 +1,95 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for illumos operating system (previously Solaris)
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "logging.h"
+#include "privops.h"
+#include "sys_solaris.h"
+#include "sys_timex.h"
+#include "util.h"
+
+#include <kvm.h>
+#include <nlist.h>
+
+/* ================================================== */
+
+static void
+set_dosynctodr(int on_off)
+{
+  struct nlist nl[] = { {"dosynctodr"}, {NULL} };
+  kvm_t *kt;
+
+  kt = kvm_open(NULL, NULL, NULL, O_RDWR, NULL);
+  if (!kt)
+    LOG_FATAL("Could not open kvm");
+
+  if (kvm_nlist(kt, nl) < 0 || !nl[0].n_value)
+    LOG_FATAL("Could not get dosynctodr address");
+
+  if (kvm_kwrite(kt, nl[0].n_value, &on_off, sizeof (on_off)) < 0)
+    LOG_FATAL("Could not write to dosynctodr");
+
+  kvm_close(kt);
+}
+
+/* ================================================== */
+
+void
+SYS_Solaris_Initialise(void)
+{
+  /* The kernel keeps the system clock and hardware clock synchronised to each
+     other.  The dosynctodr variable needs to be set to zero to prevent the
+     the system clock from following the hardware clock when the system clock
+     is not adjusted by adjtime() or ntp_adjtime(modes=MOD_OFFSET). */
+  set_dosynctodr(0);
+
+  /* The kernel allows the frequency to be set in the full range off int32_t */
+  SYS_Timex_InitialiseWithFunctions(32500, 1.0 / 100, NULL, NULL, NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Solaris_Finalise(void)
+{
+  SYS_Timex_Finalise();
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void
+SYS_Solaris_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
+{
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
+  UTI_DropRoot(uid, gid);
+}
+#endif
diff --git a/sys_solaris.h b/sys_solaris.h
new file mode 100644
index 0000000..5979232
--- /dev/null
+++ b/sys_solaris.h
@@ -0,0 +1,38 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2002
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for Solaris driver
+  */
+
+#ifndef GOT_SYS_SOLARIS_H
+#define GOT_SYS_SOLARIS_H
+
+#include "sys.h"
+
+void SYS_Solaris_Initialise(void);
+
+void SYS_Solaris_Finalise(void);
+
+void SYS_Solaris_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context);
+
+#endif
diff --git a/sys_timex.c b/sys_timex.c
new file mode 100644
index 0000000..0ee6c8e
--- /dev/null
+++ b/sys_timex.c
@@ -0,0 +1,276 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009-2012, 2014-2015, 2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Driver for systems that implement the adjtimex()/ntp_adjtime() system call
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "privops.h"
+#include "sys_generic.h"
+#include "sys_timex.h"
+#include "logging.h"
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+#define NTP_ADJTIME PRV_AdjustTimex
+#define NTP_ADJTIME_NAME "ntp_adjtime"
+#else
+#ifdef LINUX
+#define NTP_ADJTIME adjtimex
+#define NTP_ADJTIME_NAME "adjtimex"
+#else
+#define NTP_ADJTIME ntp_adjtime
+#define NTP_ADJTIME_NAME "ntp_adjtime"
+#endif
+#endif
+
+/* Maximum frequency offset accepted by the kernel (in ppm) */
+#define MAX_FREQ 500.0
+
+/* Frequency scale to convert from ppm to the timex freq */
+#define FREQ_SCALE (double)(1 << 16)
+
+/* Threshold for the timex maxerror when the kernel sets the UNSYNC flag */
+#define MAX_SYNC_ERROR 16.0
+
+/* Minimum assumed rate at which the kernel updates the clock frequency */
+#define MIN_TICK_RATE 100
+
+/* Saved timex status */
+static int sys_status;
+
+/* Saved TAI-UTC offset */
+static int sys_tai_offset;
+
+/* ================================================== */
+
+static double
+convert_timex_frequency(const struct timex *txc)
+{
+  double freq_ppm;
+
+  freq_ppm = txc->freq / FREQ_SCALE;
+
+  return -freq_ppm;
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  struct timex txc;
+
+  txc.modes = 0;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  return convert_timex_frequency(&txc);
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double freq_ppm)
+{
+  struct timex txc;
+
+  txc.modes = MOD_FREQUENCY;
+  txc.freq = freq_ppm * -FREQ_SCALE;
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  return convert_timex_frequency(&txc);
+}
+
+/* ================================================== */
+
+static void
+set_leap(int leap, int tai_offset)
+{
+  struct timex txc;
+  int applied, prev_status;
+
+  txc.modes = 0;
+  applied = SYS_Timex_Adjust(&txc, 0) == TIME_WAIT;
+
+  prev_status = sys_status;
+  sys_status &= ~(STA_INS | STA_DEL);
+
+  if (leap > 0)
+    sys_status |= STA_INS;
+  else if (leap < 0)
+    sys_status |= STA_DEL;
+
+  txc.modes = MOD_STATUS;
+  txc.status = sys_status;
+
+#ifdef MOD_TAI
+  if (tai_offset) {
+    txc.modes |= MOD_TAI;
+    txc.constant = tai_offset;
+
+    if (applied && !(sys_status & (STA_INS | STA_DEL)))
+      sys_tai_offset += prev_status & STA_INS ? 1 : -1;
+
+    if (sys_tai_offset != tai_offset) {
+      sys_tai_offset = tai_offset;
+      LOG(LOGS_INFO, "System clock TAI offset set to %d seconds", tai_offset);
+    }
+  }
+#endif
+
+  SYS_Timex_Adjust(&txc, 0);
+
+  if (prev_status != sys_status) {
+    LOG(LOGS_INFO, "System clock status %s leap second",
+        leap ? (leap > 0 ? "set to insert" : "set to delete") :
+        (applied ? "reset after" : "set to not insert/delete"));
+  }
+}
+
+/* ================================================== */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  struct timex txc;
+
+  if (synchronised) {
+    if (est_error > MAX_SYNC_ERROR)
+      est_error = MAX_SYNC_ERROR;
+    if (max_error >= MAX_SYNC_ERROR) {
+      max_error = MAX_SYNC_ERROR;
+      synchronised = 0;
+    }
+  } else {
+    est_error = max_error = MAX_SYNC_ERROR;
+  }
+
+#ifdef LINUX
+  /* On Linux clear the UNSYNC flag only if rtcsync is enabled */
+  if (!CNF_GetRtcSync())
+    synchronised = 0;
+#endif
+
+  if (synchronised)
+    sys_status &= ~STA_UNSYNC;
+  else
+    sys_status |= STA_UNSYNC;
+
+  txc.modes = MOD_STATUS | MOD_ESTERROR | MOD_MAXERROR;
+  txc.status = sys_status;
+  txc.esterror = est_error * 1.0e6;
+  txc.maxerror = max_error * 1.0e6;
+
+  if (SYS_Timex_Adjust(&txc, 1) < 0)
+    ;
+}
+
+/* ================================================== */
+
+static void
+initialise_timex(void)
+{
+  struct timex txc;
+
+  sys_status = STA_UNSYNC;
+  sys_tai_offset = 0;
+
+  /* Reset PLL offset */
+  txc.modes = MOD_OFFSET | MOD_STATUS;
+  txc.status = STA_PLL | sys_status;
+  txc.offset = 0;
+  SYS_Timex_Adjust(&txc, 0);
+
+  /* Turn PLL off */
+  txc.modes = MOD_STATUS;
+  txc.status = sys_status;
+  SYS_Timex_Adjust(&txc, 0);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_Initialise(void)
+{
+  SYS_Timex_InitialiseWithFunctions(MAX_FREQ, 1.0 / MIN_TICK_RATE, NULL, NULL, NULL,
+                                    0.0, 0.0, NULL, NULL);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_InitialiseWithFunctions(double max_set_freq_ppm, double max_set_freq_delay,
+                                  lcl_ReadFrequencyDriver sys_read_freq,
+                                  lcl_SetFrequencyDriver sys_set_freq,
+                                  lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                  double min_fastslew_offset, double max_fastslew_rate,
+                                  lcl_AccrueOffsetDriver sys_accrue_offset,
+                                  lcl_OffsetCorrectionDriver sys_get_offset_correction)
+{
+  initialise_timex();
+
+  SYS_Generic_CompleteFreqDriver(max_set_freq_ppm, max_set_freq_delay,
+                                 sys_read_freq ? sys_read_freq : read_frequency,
+                                 sys_set_freq ? sys_set_freq : set_frequency,
+                                 sys_apply_step_offset,
+                                 min_fastslew_offset, max_fastslew_rate,
+                                 sys_accrue_offset, sys_get_offset_correction,
+                                 set_leap, set_sync_status);
+}
+
+/* ================================================== */
+
+void
+SYS_Timex_Finalise(void)
+{
+  SYS_Generic_Finalise();
+}
+
+/* ================================================== */
+
+int
+SYS_Timex_Adjust(struct timex *txc, int ignore_error)
+{
+  int state;
+
+#ifdef SOLARIS
+  /* The kernel seems to check the constant even when it's not being set */
+  if (!(txc->modes & MOD_TIMECONST))
+    txc->constant = 10;
+#endif
+
+  state = NTP_ADJTIME(txc);
+
+  if (state < 0) {
+    LOG(ignore_error ? LOGS_DEBUG : LOGS_FATAL,
+        NTP_ADJTIME_NAME"(0x%x) failed : %s", txc->modes, strerror(errno));
+  }
+
+  return state;
+}
diff --git a/sys_timex.h b/sys_timex.h
new file mode 100644
index 0000000..b8617a2
--- /dev/null
+++ b/sys_timex.h
@@ -0,0 +1,48 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for a driver based on the adjtimex()/ntp_adjtime() function
+  */
+
+#ifndef GOT_SYS_TIMEX_H
+#define GOT_SYS_TIMEX_H
+
+#include "localp.h"
+
+extern void SYS_Timex_Initialise(void);
+
+/* Initialise with some driver functions replaced with special versions */
+extern void SYS_Timex_InitialiseWithFunctions(double max_set_freq_ppm, double max_set_freq_delay,
+                                              lcl_ReadFrequencyDriver sys_read_freq,
+                                              lcl_SetFrequencyDriver sys_set_freq,
+                                              lcl_ApplyStepOffsetDriver sys_apply_step_offset,
+                                              double min_fastslew_offset, double max_fastslew_rate,
+                                              lcl_AccrueOffsetDriver sys_accrue_offset,
+                                              lcl_OffsetCorrectionDriver sys_get_offset_correction);
+
+extern void SYS_Timex_Finalise(void);
+
+/* Wrapper for adjtimex()/ntp_adjtime() */
+extern int SYS_Timex_Adjust(struct timex *txc, int ignore_error);
+
+#endif  /* GOT_SYS_GENERIC_H */
diff --git a/sysincl.h b/sysincl.h
new file mode 100644
index 0000000..e26b236
--- /dev/null
+++ b/sysincl.h
@@ -0,0 +1,69 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  This file includes most system header files that the software
+  requires to better isolate system dependencies.
+  */
+
+#ifndef GOT_SYSINCL_H
+#define GOT_SYSINCL_H
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <float.h>
+#include <glob.h>
+#include <grp.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <math.h>
+#include <netinet/in.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/shm.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#if defined(LINUX) || defined(FREEBSD) || defined(NETBSD) || defined(SOLARIS) || defined(HAVE_MACOS_SYS_TIMEX)
+#include <sys/timex.h>
+#endif
+
+#ifdef HAVE_GETRANDOM
+#include <sys/random.h>
+#endif
+
+#endif /* GOT_SYSINCL_H */
diff --git a/tempcomp.c b/tempcomp.c
new file mode 100644
index 0000000..a468e33
--- /dev/null
+++ b/tempcomp.c
@@ -0,0 +1,176 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2011, 2014
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Routines implementing temperature compensation.
+
+  */
+
+#include "config.h"
+
+#include "array.h"
+#include "conf.h"
+#include "local.h"
+#include "memory.h"
+#include "util.h"
+#include "logging.h"
+#include "sched.h"
+#include "tempcomp.h"
+
+/* Sanity limit (in ppm) */
+#define MAX_COMP 10.0
+
+static SCH_TimeoutID timeout_id;
+
+static LOG_FileID logfileid;
+
+static char *filename;
+static double update_interval;
+static double T0, k0, k1, k2;
+
+struct Point {
+  double temp;
+  double comp;
+};
+
+static ARR_Instance points;
+
+static double
+get_tempcomp(double temp)
+{
+  unsigned int i;
+  struct Point *p1 = NULL, *p2 = NULL;
+
+  /* If not configured with points, calculate the compensation from the
+     specified quadratic function */
+  if (!points)
+    return k0 + (temp - T0) * k1 + (temp - T0) * (temp - T0) * k2;
+
+  /* Otherwise interpolate/extrapolate between two nearest points */
+
+  for (i = 1; i < ARR_GetSize(points); i++) {
+    p2 = (struct Point *)ARR_GetElement(points, i);
+    if (p2->temp >= temp)
+      break;
+  }
+  p1 = p2 - 1;
+
+  return (temp - p1->temp) / (p2->temp - p1->temp) *
+         (p2->comp - p1->comp) + p1->comp;
+}
+
+static void
+read_timeout(void *arg)
+{
+  FILE *f;
+  double temp, comp;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'r', 0);
+
+  if (f && fscanf(f, "%lf", &temp) == 1) {
+    comp = get_tempcomp(temp);
+
+    if (fabs(comp) <= MAX_COMP) {
+      comp = LCL_SetTempComp(comp);
+
+      DEBUG_LOG("tempcomp updated to %f for %f", comp, temp);
+
+      if (logfileid != -1) {
+        struct timespec now;
+
+        LCL_ReadCookedTime(&now, NULL);
+        LOG_FileWrite(logfileid, "%s %11.4e %11.4e",
+            UTI_TimeToLogForm(now.tv_sec), temp, comp);
+      }
+    } else {
+      LOG(LOGS_WARN, "Temperature compensation of %.3f ppm exceeds sanity limit of %.1f",
+          comp, MAX_COMP);
+    }
+  } else {
+    LOG(LOGS_WARN, "Could not read temperature from %s", filename);
+  }
+
+  if (f)
+    fclose(f);
+
+  timeout_id = SCH_AddTimeoutByDelay(update_interval, read_timeout, NULL);
+}
+
+static void
+read_points(const char *filename)
+{
+  FILE *f;
+  char line[256];
+  struct Point *p;
+
+  f = UTI_OpenFile(NULL, filename, NULL, 'R', 0);
+
+  points = ARR_CreateInstance(sizeof (struct Point));
+
+  while (fgets(line, sizeof (line), f)) {
+    p = (struct Point *)ARR_GetNewElement(points);
+    if (sscanf(line, "%lf %lf", &p->temp, &p->comp) != 2) {
+      LOG_FATAL("Could not read tempcomp point from %s", filename);
+      break;
+    }
+  }
+
+  fclose(f);
+
+  if (ARR_GetSize(points) < 2)
+    LOG_FATAL("Not enough points in %s", filename);
+}
+
+void
+TMC_Initialise(void)
+{
+  char *point_file;
+
+  CNF_GetTempComp(&filename, &update_interval, &point_file, &T0, &k0, &k1, &k2);
+
+  if (filename == NULL)
+    return;
+
+  if (update_interval <= 0.0)
+    update_interval = 1.0;
+
+  if (point_file)
+    read_points(point_file);
+
+  logfileid = CNF_GetLogTempComp() ? LOG_FileOpen("tempcomp",
+      "   Date (UTC) Time        Temp.       Comp.")
+    : -1;
+
+  read_timeout(NULL);
+}
+
+void
+TMC_Finalise(void)
+{
+  if (filename == NULL)
+    return;
+
+  if (points)
+    ARR_DestroyInstance(points);
+
+  SCH_RemoveTimeout(timeout_id);
+}
diff --git a/tempcomp.h b/tempcomp.h
new file mode 100644
index 0000000..b876f90
--- /dev/null
+++ b/tempcomp.h
@@ -0,0 +1,29 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2011
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for temperature compensation.
+
+  */
+
+extern void TMC_Initialise(void);
+extern void TMC_Finalise(void);
diff --git a/test/compilation/001-features b/test/compilation/001-features
new file mode 100755
index 0000000..9bd340f
--- /dev/null
+++ b/test/compilation/001-features
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+# Try to compile chrony in various combinations of disabled features
+
+cd ../..
+
+export CFLAGS="-O2 -Werror -Wpointer-arith -Wformat-signedness -Wno-unknown-warning-option -D_FORTIFY_SOURCE=2"
+
+for opts in \
+	"--enable-debug" \
+	"--enable-ntp-signd" \
+	"--enable-scfilter" \
+	"--disable-asyncdns" \
+	"--disable-ipv6" \
+	"--disable-privdrop" \
+	"--disable-readline" \
+	"--disable-rtc" \
+	"--disable-sechash" \
+	"--disable-cmdmon" \
+	"--disable-cmdmon --enable-scfilter" \
+	"--disable-ntp" \
+	"--disable-ntp --enable-scfilter" \
+	"--disable-nts" \
+	"--disable-refclock" \
+	"--disable-timestamping" \
+	"--disable-timestamping --disable-ntp" \
+	"--disable-cmdmon --disable-ntp" \
+	"--disable-cmdmon --disable-ntp --enable-scfilter" \
+	"--disable-cmdmon --disable-refclock" \
+	"--disable-cmdmon --disable-ntp --disable-refclock"
+do
+	./configure $opts || exit 1
+	make clean
+	make "$@" || exit 1
+	make -C test/unit check || exit 1
+done
diff --git a/test/compilation/002-scanbuild b/test/compilation/002-scanbuild
new file mode 100755
index 0000000..35a3faf
--- /dev/null
+++ b/test/compilation/002-scanbuild
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+cd ../..
+
+for opts in \
+	"--host-system=Linux" \
+	"--host-system=NetBSD" \
+	"--host-system=FreeBSD" \
+	"--without-nettle" \
+	"--without-nettle --without-nss" \
+	"--without-nettle --without-nss --without-tomcrypt" \
+	"--without-nettle --without-nss --without-tomcrypt --without-gnutls"
+do
+	./configure $opts
+	scan-build make "$@" || exit 1
+done
diff --git a/test/compilation/003-sanitizers b/test/compilation/003-sanitizers
new file mode 100755
index 0000000..2edd6e6
--- /dev/null
+++ b/test/compilation/003-sanitizers
@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+# Run the unit and simulation tests with different compiler sanitizers
+# and under valgrind
+
+valgrind_opts="--leak-check=full --errors-for-leak-kinds=definite"
+
+cd ../..
+
+if [ "$(uname -sm)" != "Linux x86_64" ]; then
+  echo Test supported on Linux x86_64 only
+  exit 1
+fi
+
+[ -f /etc/os-release ] && . /etc/os-release
+
+if [ "$ID" = "fedora" ]; then
+  echo Checking test dependencies:
+  rpm -q {gcc,clang}.x86_64 {valgrind,libgcc,clang-libs}.{x86_64,i686} || exit 1
+  rpm -q {libseccomp,nettle,nss-softokn-freebl,libtomcrypt,gnutls}-devel.{x86_64,i686} || exit 1
+  echo
+fi
+
+touch Makefile
+
+for extra_config_opts in \
+  "--all-privops" \
+  "--disable-ipv6" \
+  "--disable-scfilter" \
+  "--without-aes-gcm-siv" \
+  "--without-gnutls" \
+  "--without-nettle" \
+  "--without-nettle --without-nss" \
+  "--without-nettle --without-nss --without-tomcrypt" \
+  "--without-nettle --without-nss --without-tomcrypt --without-gnutls"; \
+do
+  for arch_opts in "-m32" ""; do
+    pushd test/simulation/clknetsim || exit 1
+    make clean > /dev/null 2>&1
+    CFLAGS="$arch_opts -DCLKNETSIM_DISABLE_SYSCALL" make "$@" || exit 1
+    echo
+
+    popd
+
+    for CC in gcc clang; do
+      export CC
+
+      for san_options in "" "-fsanitize=address" "-fsanitize=memory"; do
+        export CFLAGS="-O2 -g -fsanitize=undefined -fsanitize=float-divide-by-zero -fsanitize=float-cast-overflow -fno-sanitize-recover=all $san_options $arch_opts"
+
+        # clang msan doesn't work on i686 and otherwise requires patches
+        echo $CFLAGS | grep -q 'sanitize=memory' && continue
+
+        [ -n "$TEST_NO_M32_CLANG" -a "$arch_opts" = "-m32" -a "$CC" = "clang" ] && continue
+
+        [ -n "$TEST_GCC_STATIC_ASAN" -a "$CC" = "gcc" ] &&
+                echo $CFLAGS | grep -q 'sanitize=address' && CFLAGS="$CFLAGS -static-libasan"
+
+        config_opts="--with-user=chrony --with-ntp-era=1000000000 --enable-debug --enable-scfilter --enable-ntp-signd $extra_config_opts"
+
+        echo -----------------------------------------------------------------------------
+        echo CC=\"$CC\" CFLAGS=\"$CFLAGS\" ./configure $config_opts
+
+        make distclean > /dev/null 2>&1
+
+        ./configure $config_opts || exit 1
+
+        if echo "$config_opts" | grep -q all-privops; then
+          for op in ADJUSTTIME ADJUSTTIMEX SETTIME BINDSOCKET; do
+            echo "#define PRIVOPS_$op 1" >> config.h
+          done
+        fi
+
+        make "$@" || exit 1
+
+        [ -n "$TEST_BUILD_ONLY" ] && continue
+
+        echo
+        pushd test/unit || exit 1
+        make "$@" || exit 1
+        if [ "$san_options" = "" ]; then
+          make check TEST_WRAPPER="valgrind $valgrind_opts --error-exitcode=1" || exit 1
+        else
+          make check || exit 1
+        fi
+        popd
+
+        [ -n "$TEST_UNIT_ONLY" ] && continue
+
+        echo
+        pushd test/simulation || exit 1
+        export CLKNETSIM_RANDOM_SEED=101
+        if [ "$arch_opts" = "" -a "$san_options" = "" ]; then
+          CLKNETSIM_CLIENT_WRAPPER="valgrind $valgrind_opts" ./run -i 1 || exit 1
+        elif [ "$CC" = "gcc" ] && ! echo $CFLAGS | grep -q "-static-libasan"; then
+          libasan=$(ldd ../../chronyd | grep -o '/.*lib.*/libasan.so.[0-9]')
+          CLKNETSIM_PRELOAD=$libasan ./run -i 1 || exit 1
+        else
+          ./run -i 1 || exit 1
+        fi
+        popd
+      done
+    done
+  done
+done
diff --git a/test/kernel/Makefile b/test/kernel/Makefile
new file mode 100644
index 0000000..6ec8341
--- /dev/null
+++ b/test/kernel/Makefile
@@ -0,0 +1,7 @@
+CFLAGS=-O2 -Wall
+PROGS=adjtime ntpadjtime
+
+all: $(PROGS)
+
+clean:
+	rm -f $(PROGS)
diff --git a/test/kernel/adjtime.c b/test/kernel/adjtime.c
new file mode 100644
index 0000000..0ca8ff2
--- /dev/null
+++ b/test/kernel/adjtime.c
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+/* Test the system adjtime() function. Check the range of supported offset,
+   support for readonly operation, and slew rate with different update
+   intervals and offsets. */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+static int
+diff_tv(struct timeval *tv1, struct timeval *tv2)
+{
+  return 1000000 * (tv1->tv_sec - tv2->tv_sec) + (tv1->tv_usec - tv2->tv_usec);
+}
+
+static struct timeval
+usec_to_tv(int usec)
+{
+  struct timeval tv;
+
+  tv.tv_sec = usec / 1000000;
+  tv.tv_usec = usec % 1000000;
+
+  return tv;
+}
+
+static int
+try_adjtime(struct timeval *new, struct timeval *old)
+{
+  int r;
+
+  r = adjtime(new, old);
+  if (r)
+    printf("adjtime() failed : %s ", strerror(errno));
+  return r;
+}
+
+static void
+reset_adjtime(void)
+{
+  struct timeval tv;
+
+  tv = usec_to_tv(0);
+  try_adjtime(&tv, NULL);
+}
+
+static void
+test_range(void)
+{
+  struct timeval tv;
+  int i;
+
+  printf("range:\n");
+
+  for (i = 0; i < sizeof (time_t) * 8; i++) {
+    tv.tv_usec = 0;
+    tv.tv_sec = (1ULL << i) - 1;
+    printf("%20lld s : ", (long long)tv.tv_sec);
+    printf("%s\n", !try_adjtime(&tv, NULL) ? "ok" : "");
+    tv.tv_sec = ~tv.tv_sec;
+    printf("%20lld s : ", (long long)tv.tv_sec);
+    printf("%s\n", !try_adjtime(&tv, NULL) ? "ok" : "");
+  }
+}
+
+static void
+test_readonly(void)
+{
+  struct timeval tv1, tv2;
+  int i, r;
+
+  printf("readonly:\n");
+
+  for (i = 0; i <= 20; i++) {
+    tv1 = usec_to_tv(1 << i);
+
+    printf("%9d us : ", 1 << i);
+    try_adjtime(&tv1, NULL);
+    r = !try_adjtime(NULL, &tv2) && !diff_tv(&tv1, &tv2);
+    printf("%s\n", r ? "ok" : "fail");
+  }
+}
+
+static void
+test_readwrite(void)
+{
+  struct timeval tv1, tv2, tv3;
+  int i, r;
+
+  printf("readwrite:\n");
+
+  for (i = 0; i <= 20; i++) {
+    tv1 = usec_to_tv(1 << i);
+    tv3 = usec_to_tv(0);
+
+    printf("%9d us : ", 1 << i);
+    try_adjtime(&tv1, NULL);
+    r = !try_adjtime(&tv3, &tv2) && !diff_tv(&tv1, &tv2);
+    printf("%s\n", r ? "ok" : "fail");
+  }
+}
+
+static void
+xusleep(int usec)
+{
+  struct timeval tv;
+
+  tv = usec_to_tv(usec);
+  select(0, NULL, NULL, NULL, &tv);
+}
+
+static void
+test_slew(void)
+{
+  struct timeval tv1, tv2, tv3;
+  int i, j, k, diff, min, has_min;
+
+  printf("slew:\n");
+
+  for (i = 9; i <= 20; i++) {
+    printf("%9d us : ", 1 << i);
+    for (j = 4; j <= 20; j += 4) {
+      for (min = has_min = 0, k = 4; k < 16; k += 2) {
+
+        tv1 = usec_to_tv(1 << j);
+        tv3 = usec_to_tv(0);
+
+        xusleep(1 << i);
+        reset_adjtime();
+
+        xusleep(1 << i);
+        if (try_adjtime(&tv1, NULL))
+          continue;
+
+        xusleep(1 << i);
+        if (try_adjtime(&tv3, &tv2))
+          continue;
+
+        diff = diff_tv(&tv1, &tv2);
+        if (!has_min || min > diff) {
+          min = diff;
+          has_min = 1;
+        }
+      }
+
+      if (!has_min)
+        continue;
+
+      printf(" %5d (%d)", min, 1 << j);
+      fflush(stdout);
+    }
+    printf("\n");
+  }
+}
+
+int
+main()
+{
+  test_range();
+  test_readonly();
+  test_readwrite();
+  test_slew();
+
+  reset_adjtime();
+
+  return 0;
+}
diff --git a/test/kernel/ntpadjtime.c b/test/kernel/ntpadjtime.c
new file mode 100644
index 0000000..4af96b4
--- /dev/null
+++ b/test/kernel/ntpadjtime.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) Miroslav Lichvar  2015
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+/* Check the frequency range of the system ntp_adjtime() implementation */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+
+static int
+try_ntpadjtime(struct timex *t)
+{
+  int r;
+  r = ntp_adjtime(t);
+  if (r < 0)
+    printf("ntp_adjtime() failed : %s ", strerror(errno));
+  return r;
+}
+
+static void
+reset_ntpadjtime(void)
+{
+  struct timex t;
+
+  t.modes = MOD_OFFSET | MOD_FREQUENCY;
+  t.offset = 0;
+  t.freq = 0;
+  try_ntpadjtime(&t);
+}
+
+static void
+test_freqrange(void)
+{
+  struct timex t;
+  int i;
+
+  printf("freq range:\n");
+
+  for (i = -1000; i <= 1000; i += 50) {
+    t.modes = MOD_FREQUENCY;
+    t.freq = i * (1 << 16);
+    printf("%4d ppm => ", i);
+    if (try_ntpadjtime(&t) < 0)
+      continue;
+
+    printf("%4ld ppm : ", t.freq / (1 << 16));
+    printf("%s\n", t.freq == i * (1 << 16) ? "ok" : "fail");
+  }
+}
+
+int
+main()
+{
+  test_freqrange();
+
+  reset_ntpadjtime();
+
+  return 0;
+}
diff --git a/test/simulation/001-defaults b/test/simulation/001-defaults
new file mode 100755
index 0000000..b39d95c
--- /dev/null
+++ b/test/simulation/001-defaults
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "default test settings"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/002-largenetwork b/test/simulation/002-largenetwork
new file mode 100755
index 0000000..a9e0ad8
--- /dev/null
+++ b/test/simulation/002-largenetwork
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large network"
+
+time_rms_limit=5e-4
+
+server_strata=3
+servers=4
+clients=5
+
+client_start=2000
+min_sync_time=2100
+max_sync_time=2300
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/003-largefreqoffset b/test/simulation/003-largefreqoffset
new file mode 100755
index 0000000..9381b1a
--- /dev/null
+++ b/test/simulation/003-largefreqoffset
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large frequency offset"
+
+max_sync_time=1000
+
+for freq_offset in -5e-2 -5e-3 5e-3 5e-2; do
+	# Adjust offset so it's close to 0 on first clock update
+	time_offset=$(awk "BEGIN {print -($freq_offset * 130)}")
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/004-largetimeoffset b/test/simulation/004-largetimeoffset
new file mode 100755
index 0000000..4aebdd3
--- /dev/null
+++ b/test/simulation/004-largetimeoffset
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large time offset"
+
+min_sync_time=1300
+max_sync_time=1400
+
+for time_offset in -1e2 1e2; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/005-externalstep b/test/simulation/005-externalstep
new file mode 100755
index 0000000..e6fff26
--- /dev/null
+++ b/test/simulation/005-externalstep
@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "external time step"
+
+min_sync_time=1500
+max_sync_time=1550
+
+for step in -1e2 1e2; do
+	# Make one step in 150th second
+	client_step="(* $step (equal 0.1 (sum 1.0) 150))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=5120
+max_sync_time=6200
+client_conf="makestep 1 -1"
+
+for step in -1e8 -1e5 1e5 1e8; do
+	# Make one step in 5000th second
+	client_step="(* $step (equal 0.1 (sum 1.0) 5000))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+time_max_limit=2e4
+time_rms_limit=8e3
+
+for step in -1e4 1e4; do
+	# Make a step every 500 seconds
+	client_step="(* $step (equal 0.1 (% (sum 1.0) 500) 0))"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/006-largejitter b/test/simulation/006-largejitter
new file mode 100755
index 0000000..36ae5e2
--- /dev/null
+++ b/test/simulation/006-largejitter
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large jitter"
+
+time_offset=1e0
+jitter=1e-1
+
+time_max_limit=5e-1
+freq_max_limit=2e-1
+time_rms_limit=1e-1
+freq_rms_limit=5e-3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/007-largewander b/test/simulation/007-largewander
new file mode 100755
index 0000000..af0c599
--- /dev/null
+++ b/test/simulation/007-largewander
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "large wander"
+
+wander=1e-7
+
+time_max_limit=5e-3
+freq_max_limit=5e-3
+time_rms_limit=1e-3
+freq_rms_limit=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/008-ntpera b/test/simulation/008-ntpera
new file mode 100755
index 0000000..2eea63b
--- /dev/null
+++ b/test/simulation/008-ntpera
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "NTP eras"
+
+if check_config_h 'HAVE_LONG_TIME_T 1'; then
+	ntp_start=$(awk "BEGIN {print $(grep NTP_ERA_SPLIT ../../config.h | tr -dc '0-9*+-')}")
+else
+	ntp_start="-2147483648"
+fi
+
+# Set the starting test date to 500 seconds before the second NTP era.
+# This should work with 32-bit time_t and also with 64-bit time_t if the
+# configured NTP interval covers the test interval.
+export CLKNETSIM_START_DATE=$(date -d 'Feb  7 06:19:56 UTC 2036' +'%s')
+
+if awk "BEGIN {exit !($ntp_start <= $CLKNETSIM_START_DATE && \
+		$CLKNETSIM_START_DATE + $limit < $ntp_start + 2^32)}"; then
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+fi
+
+# The following tests need 64-bit time_t and ntp_start not before 1970
+check_config_h 'HAVE_LONG_TIME_T 1' || test_skip
+echo "$ntp_start" | grep -q '-' && test_skip
+
+for time_offset in -1e-1 1e-1; do
+	for start_offset in 0 "2^32 - $limit"; do
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync || test_fail
+	done
+
+	for start_offset in -$limit "2^32"; do
+		export CLKNETSIM_START_DATE=$(awk "BEGIN {printf \"%.0f\", $ntp_start + $start_offset}")
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync && test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/009-sourceselection b/test/simulation/009-sourceselection
new file mode 100755
index 0000000..547c376
--- /dev/null
+++ b/test/simulation/009-sourceselection
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "source selection"
+
+# Falsetickers should be detected if their number is less than half of all
+
+base_delay=1e-3
+servers=5
+
+for falsetickers in 1 2; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+for falsetickers in 3 4; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	# These check are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+# Sources with large asymmetric delay should be excluded
+
+servers=3
+falsetickers=0
+base_delay="(+ 1e-3 (equal 0.1 to 2) (equal 0.1 to 3))"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/010-multrecv b/test/simulation/010-multrecv
new file mode 100755
index 0000000..36e7476
--- /dev/null
+++ b/test/simulation/010-multrecv
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+export CLKNETSIM_RECV_MULTIPLY=4
+
+test_start "multiple received packets"
+
+limit=50000
+client_server_options="minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/011-asymjitter b/test/simulation/011-asymjitter
new file mode 100755
index 0000000..9fb5567
--- /dev/null
+++ b/test/simulation/011-asymjitter
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "asymmetric jitter"
+
+jitter=5e-4
+jitter_asymmetry=0.47
+limit=100000
+max_sync_time=2000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/012-daemonts b/test/simulation/012-daemonts
new file mode 100755
index 0000000..a1b90e3
--- /dev/null
+++ b/test/simulation/012-daemonts
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "daemon timestamping"
+
+export CLKNETSIM_TIMESTAMPING=0
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/013-nameserv b/test/simulation/013-nameserv
new file mode 100755
index 0000000..941026b
--- /dev/null
+++ b/test/simulation/013-nameserv
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "name resolving"
+
+dns=1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/101-poll b/test/simulation/101-poll
new file mode 100755
index 0000000..1416b22
--- /dev/null
+++ b/test/simulation/101-poll
@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "minpoll/maxpoll options"
+
+wander=0.0
+jitter=1e-6
+
+time_max_limit=1e-5
+freq_max_limit=1e-5
+time_rms_limit=5e-6
+freq_rms_limit=5e-6
+client_conf="makestep 1e-2 1"
+
+for poll in $(seq 1 14); do
+	client_server_options="minpoll $poll maxpoll $poll"
+	limit=$[2**$poll * 10]
+	min_sync_time=$[2**$poll * 2]
+	max_sync_time=$[2**$poll * 21 / 10 + 1]
+	client_max_min_out_interval=$(awk "BEGIN {print 2^$poll * 1.1}")
+	client_min_mean_out_interval=$(awk "BEGIN {print 2^$poll * 0.99}")
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+client_max_min_out_interval=$default_client_max_min_out_interval
+client_min_mean_out_interval=$default_client_min_mean_out_interval
+
+limit=10
+
+for poll in $(seq -7 2 -1); do
+	client_server_options="minpoll $poll maxpoll $poll"
+
+	base_delay=1e-4
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_file_messages "	2	1	" \
+		$[2**-poll * limit * 9 / 10] $[2**-poll * limit] log.packets || test_fail
+
+	base_delay=2e-2
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_file_messages "	2	1	" $[limit * 9 / 10] $limit log.packets || test_fail
+done
+
+test_pass
diff --git a/test/simulation/102-iburst b/test/simulation/102-iburst
new file mode 100755
index 0000000..9936572
--- /dev/null
+++ b/test/simulation/102-iburst
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "iburst option"
+
+freq_offset=1e-4
+
+client_conf="makestep 1e-2 1
+driftfile tmp/drift"
+client_server_options="iburst"
+
+min_sync_time=4
+max_sync_time=6
+
+echo "100 1.0" > tmp/drift
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/103-initstepslew b/test/simulation/103-initstepslew
new file mode 100755
index 0000000..fe47b68
--- /dev/null
+++ b/test/simulation/103-initstepslew
@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "initstepslew directive"
+
+freq_offset=0.0
+wander=0.0
+time_rms_limit=1e-3
+limit=100
+
+client_conf="initstepslew 5 192.168.123.1"
+client_server_conf="#"
+
+min_sync_time=6
+max_sync_time=35
+
+for time_offset in -2.0 -0.2 0.2 2.0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	check_log_messages "00:00:0.Z System's initial.*slew" 1 1 || test_fail
+done
+
+min_sync_time=5
+max_sync_time=5
+
+for time_offset in -1e8 -1e2 1e2 1e8; do
+	run_test || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	check_log_messages "System's initial.*step" 1 1 || test_fail
+done
+
+time_offset=3
+limit=500
+servers=2
+falsetickers=1
+client_conf="initstepslew 5 192.168.123.1 192.168.123.2"
+client_server_conf="server 192.168.123.2"
+
+min_sync_time=360
+max_sync_time=450
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_log_messages "00:03:2.Z No suitable source for initstepslew" 1 1 || test_fail
+
+client_conf="initstepslew 5 192.168.123.1 192.168.123.2"
+
+min_sync_time=1
+max_sync_time=500
+server_conf="deny all"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync && test_fail
+check_log_messages "00:00:1.Z No suitable source for initstepslew" 1 1 || test_fail
+
+test_pass
diff --git a/test/simulation/104-driftfile b/test/simulation/104-driftfile
new file mode 100755
index 0000000..93d4363
--- /dev/null
+++ b/test/simulation/104-driftfile
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "driftfile directive"
+
+servers=0
+time_offset=0.0
+wander=0.0
+limit=10
+freq_max_limit=1e-9
+min_sync_time=1
+max_sync_time=1
+client_conf="driftfile tmp/drift"
+
+for freq_offset in -5e-2 -5e-4 -5e-6 5e-6 5e-4 5e-2; do
+	awk "BEGIN {printf \"%.9e 1\", 1e6 - 1 / (1 + $freq_offset) * 1e6}" > tmp/drift
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/105-ntpauth b/test/simulation/105-ntpauth
new file mode 100755
index 0000000..1f228f5
--- /dev/null
+++ b/test/simulation/105-ntpauth
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP authentication"
+
+server_conf="keyfile tmp/server.keys"
+client_conf="keyfile tmp/client.keys"
+
+cat > tmp/server.keys <<-EOF
+1 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+2 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+3 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+4 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+EOF
+
+cat > tmp/client.keys <<-EOF
+1 k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+2 ASCII:k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+3 MD5 ASCII:k]<j.Jtw^Oo;z5E>n\_0-x=)yP\f<)Z^
+4 MD5 HEX:6B5D3C6A2E4A74775E4F6F3B7A35453E6E5C5F302D783D2979505C663C295A5E
+EOF
+
+keys=4
+
+types="MD5"
+check_config_h 'FEAT_SECHASH 1' && types="$types SHA1 SHA256 SHA384 SHA512"
+check_config_h 'HAVE_CMAC 1' && types="$types AES128 AES256"
+
+for type in $types; do
+	keys=$[$keys + 1]
+	case $type in
+		AES128)	length=16;;
+		AES256)	length=32;;
+		*)	length=$[$RANDOM % 32 + 1];;
+	esac
+
+	key=$(echo $keys $type HEX:$(tr -c -d '0-9A-F' < /dev/urandom 2> /dev/null | \
+		head -c $[$length * 2]))
+	echo "$key" >> tmp/server.keys
+	echo "$key" >> tmp/client.keys
+done
+
+for version in 3 4; do
+	for key in $(seq $keys); do
+		client_server_options="version $version key $key"
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_packet_interval || test_fail
+		check_sync || test_fail
+	done
+done
+
+server_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the server doesn't know the key
+check_sync && test_fail
+check_packet_interval || test_fail
+
+server_conf="keyfile tmp/server.keys"
+client_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the client doesn't know the key
+check_sync && test_fail
+check_packet_interval || test_fail
+
+client_conf="keyfile tmp/client.keys"
+clients=2
+peers=2
+max_sync_time=500
+base_delay="$default_base_delay (* -1 (equal 0.1 from 3) (equal 0.1 to 1))"
+
+for versions in "3 3" "3 4" "4 3" "4 4"; do
+	for key in 1 $keys; do
+		client_lpeer_options="version ${versions% *} key $key"
+		client_rpeer_options="version ${versions#* } key $key"
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_sync || test_fail
+	done
+done
+
+client_lpeer_options="key 1"
+client_rpeer_options="key 2"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# This check must fail as the peers are using different keys"
+check_sync && test_fail
+
+test_pass
diff --git a/test/simulation/106-refclock b/test/simulation/106-refclock
new file mode 100755
index 0000000..ba7c482
--- /dev/null
+++ b/test/simulation/106-refclock
@@ -0,0 +1,143 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "reference clocks"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+check_config_h 'FEAT_PHC 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+export CLKNETSIM_PHC_DELAY=1e-6
+export CLKNETSIM_PHC_JITTER=1e-7
+
+servers=0
+limit=1000
+refclock_jitter=$jitter
+min_sync_time=45
+max_sync_time=70
+chronyc_start=70
+chronyc_conf="tracking"
+
+for refclock in "SHM 0" "PHC /dev/ptp0" "PHC /dev/ptp0:nocrossts"; do
+	client_conf="refclock $refclock stratum 3 delay 1e-3 refid GPS
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*47505300 \(GPS\)
+Stratum.*: 4
+.*
+Root delay      : 0.001000000 seconds
+.*
+Update interval : 16\.. seconds
+.*$" || test_fail
+
+	if echo "$refclock" | grep -q 'PHC.*nocrossts'; then
+		check_file_messages "20.* GPS.*[0-9] N " 650 750 refclocks.log || test_fail
+	else
+		check_file_messages "20.* GPS.*[0-9] N " 997 1001 refclocks.log || test_fail
+	fi
+	check_file_messages "20.* GPS.*- N " 61 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+done
+
+if check_config_h 'FEAT_PPS 1'; then
+	refclock_offset=0.35
+	refclock_jitter=0.05
+
+	client_conf="
+refclock SHM 0 refid NMEA noselect
+refclock PPS /dev/pps0 lock NMEA
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 1
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 620 740 refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 60 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+
+	client_conf="
+refclock SHM 0 noselect
+refclock PPS /dev/pps0
+local
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 10
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 997 1001 refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 60 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+
+	min_sync_time=100
+	max_sync_time=220
+	chronyc_start=220
+	client_conf="
+refclock SHM 0 refid NMEA offset 0.35 delay 0.1
+refclock PPS /dev/pps0
+logdir tmp
+log refclocks"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+	check_chronyc_output "^Reference ID.*50505331 \(PPS1\)
+Stratum.*: 1
+.*
+Root delay      : 0\.000000001 seconds
+.*$" || test_fail
+
+	check_file_messages "20.* PPS1.*[0-9] N " 800 940  refclocks.log || test_fail
+	check_file_messages "20.* PPS1.*- N " 50 63 refclocks.log || test_fail
+	rm -f tmp/refclocks.log
+fi
+
+refclock_offset="(+ 0.399 (sum 1e-3))"
+refclock_jitter=1e-6
+servers=1
+freq_offset="(* 1e-4 (sine 1000))"
+base_delay="(* -1.0 (equal 0.1 (min time 5000) 5000))"
+client_server_options="minpoll 4 maxpoll 4 filter 5 minsamples 64"
+client_conf="
+refclock PHC /dev/ptp0 local poll 2
+logdir tmp
+log refclocks tracking"
+chronyc_conf=""
+limit=10000
+max_sync_time=5000
+time_max_limit=1e-3
+time_rms_limit=5e-4
+freq_max_limit=2e-5
+freq_rms_limit=5e-6
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+check_file_messages "20.* PHC0 .* [0-9] ? " 9999 10001 refclocks.log || test_fail
+check_file_messages "20.* PHC0 .* - ? " 2499 2501 refclocks.log || test_fail
+check_file_messages "20.* PHC0 " 0 0 tracking.log || test_fail
+rm -f tmp/refclocks.log tmp/tracking.log
+
+test_pass
diff --git a/test/simulation/107-allowdeny b/test/simulation/107-allowdeny
new file mode 100755
index 0000000..4665337
--- /dev/null
+++ b/test/simulation/107-allowdeny
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "allow/deny directives"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=500
+
+# Note that start_client in clknetsim.bash always adds allow to the config
+
+for server_conf in \
+	"deny" \
+	"deny all" \
+	"deny 192.168.0.0/16" \
+	"deny 192.168.123" \
+	"deny 192.168.123.2" \
+	"deny all
+allow 192.168.124.0/24"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	# These checks are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+for server_conf in \
+	"deny all
+allow" \
+	"deny all
+allow all" \
+	"deny all
+allow 192.168.123" \
+	"deny all
+allow 192.168.123/24" \
+	"deny 192.168.124.0/24"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/108-peer b/test/simulation/108-peer
new file mode 100755
index 0000000..906de17
--- /dev/null
+++ b/test/simulation/108-peer
@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP peers"
+
+# Allow and drop packets to the server in 1000 second intervals, so only one
+# client has access to it and the other is forced to switch to the peer.
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (% time 2000) 1000) 1000))
+     (* -1
+        (equal 0.1 from 3)
+        (equal 0.1 to 1)
+	(equal 0.1 (max (% time 2000) 1000) 1000)))
+EOF
+)
+
+clients=2
+peers=2
+max_sync_time=1000
+client_server_options="minpoll 6 maxpoll 6"
+client_peer_options="minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))"
+client_peer_options=""
+
+while read lminpoll lmaxpoll rminpoll rmaxpoll max_sync_time; do
+	client_lpeer_options="minpoll $lminpoll maxpoll $lmaxpoll"
+	client_rpeer_options="minpoll $rminpoll maxpoll $rmaxpoll"
+	limit=$[$max_sync_time * 10]
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_sync || test_fail
+done <<-EOF
+	3 6 3 6 400
+	3 3 6 6 450
+	6 6 3 3 450
+	3 6 6 6 450
+	6 6 3 6 450
+	-2 -2 2 2 220
+	2 2 -2 -2 220
+EOF
+
+test_pass
diff --git a/test/simulation/109-makestep b/test/simulation/109-makestep
new file mode 100755
index 0000000..78d8d59
--- /dev/null
+++ b/test/simulation/109-makestep
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "makestep directive"
+
+client_conf="makestep 0 -1
+corrtimeratio 1e10"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+limit=200
+jitter=1e-5
+client_conf="makestep 2 1"
+
+min_sync_time=130
+max_sync_time=150
+
+for time_offset in -1.0 -0.1 0.1 1.0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+min_sync_time=120
+max_sync_time=140
+
+for time_offset in -1e8 -1e2 1e2 1e8; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/110-chronyc b/test/simulation/110-chronyc
new file mode 100755
index 0000000..97abc21
--- /dev/null
+++ b/test/simulation/110-chronyc
@@ -0,0 +1,529 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "chronyc"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+refclock_jitter=$jitter
+client_server_conf="
+server node1.net1.clk
+server 192.168.123.2"
+client_conf="
+refclock SHM 0 noselect
+smoothtime 400 0.001 leaponly"
+cmdmon_unix=0
+
+chronyc_conf="activity
+tracking
+sourcename 192.168.123.1
+sourcename 192.168.123.2
+sources
+sourcestats
+manual list
+smoothing
+waitsync
+rtcdata"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+2 sources online
+0 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address
+Reference ID    : C0A87B01 \(192\.168\.123\.1\)
+Stratum         : 2
+Ref time \(UTC\)  : Fri Jan 01 00:1.:.. 2010
+System time     : 0\.0000..... seconds (slow|fast) of NTP time
+Last offset     : [+-]0\.000...... seconds
+RMS offset      : 0\.000...... seconds
+Frequency       : (99|100)\.... ppm fast
+Residual freq   : [+-][0-9]\.... ppm
+Skew            : [0-9]\.... ppm
+Root delay      : 0\.000...... seconds
+Root dispersion : 0\.000...... seconds
+Update interval : [0-9]+\.. seconds
+Leap status     : Normal
+node1\.net1\.clk
+192\.168\.123\.2
+MS Name/IP address         Stratum Poll Reach LastRx Last sample               
+===============================================================================
+#\? SHM0                          0   4   377    [0-9]+ [0-9 +-]+[un]s\[[0-9 +-]+[un]s\] \+/-[ 0-9]+[un]s
+\^\* 192\.168\.123\.1                 1   [67]   377    [0-9]+ [0-9 +-]+[un]s\[[0-9 +-]+[un]s\] \+/-[ 0-9]+[un]s
+\^\? 192\.168\.123\.2                 0   [0-9]+     0     -     \+0ns\[   \+0ns\] \+/-    0ns
+Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
+==============================================================================
+SHM0                       [0-9 ]+ [0-9 ]+ [0-9 ]+ [ +-][01]\.... [0-9 ]+\....  [0-9 +-]+[un]s [0-9 ]+[un]s
+192\.168\.123\.1              [0-9 ]+ [0-9 ]+ [0-9 ]+ [ +-][01]\.... [0-9 ]+\....  [0-9 +-]+[un]s [0-9 ]+[un]s
+192\.168\.123\.2               0   0     0     \+0\.000   2000\.000     \+0ns  4000ms
+210 n_samples = 0
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+Active         : Yes \(leap second only\)
+Offset         : \+0\.000000000 seconds
+Frequency      : \+0\.000000 ppm
+Wander         : \+0\.000000 ppm per second
+Last update    : [0-9]+\.. seconds ago
+Remaining time : 0\.0 seconds
+try: 1, refid: C0A87B01, correction: 0\.000......, skew: .\....
+513 RTC driver not running$" \
+|| test_fail
+
+chronyc_conf="tracking"
+dns=1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^Reference ID    : C0A87B01 \(node1\.net1\.clk\)" \
+	|| test_fail
+
+chronyc_options="-c"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^C0A87B01,192\.168\.123\.1,2,12623049..\..........,-?0\.0000.....,-?0\.000......,0\.000......,(99|100)\....,-?[0-9]\....,[0-9]\....,0\.000......,0\.000......,[0-9]+\..,Normal$" \
+	|| test_fail
+
+chronyc_options="-c -e"
+chronyc_conf="sources"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^#,.,SHM0.*
+\^,.,192\.168\.123\.1.*
+\^,.,192\.168\.123\.2.*
+\.$" \
+	|| test_fail
+
+chronyc_options=""
+server_strata=0
+chronyc_start=0.5
+client_server_conf=""
+client_conf=""
+server_conf="server 192.168.123.1"
+limit=1
+
+for chronyc_conf in \
+	"accheck 1.2.3.4" \
+	"add peer 10.0.0.0 minpoll 2 maxpoll 6" \
+	"add server 10.0.0.0 minpoll 6 maxpoll 10 iburst burst key 1 certset 2 maxdelay 1e-3 maxdelayratio 10.0 maxdelaydevratio 10.0 maxdelayquant 0.5 mindelay 1e-4 asymmetry 0.5 offset 1e-5 minsamples 6 maxsamples 6 filter 3 offline auto_offline prefer noselect trust require xleave polltarget 20 port 123 presend 7 minstratum 3 version 4 nts ntsport 4460 copy extfield F323" \
+	"add server node1.net1.clk" \
+	"allow 1.2.3.4" \
+	"allow 1.2" \
+	"allow 3.4.5" \
+	"allow 6.7.8/22" \
+	"allow 6.7.8.9/22" \
+	"allow 0/0" \
+	"allow" \
+	"allow all 10/24" \
+	"authdata" \
+	"burst 5/10" \
+	"burst 3/5 255.255.255.0/1.2.3.0" \
+	"burst 1/2 1.2.3.0/24" \
+	"clients" \
+	"clients -k" \
+	"clients -p 100" \
+	"clients -r" \
+	"cmdaccheck 1.2.3.4" \
+	"cmdallow 1.2.3.4" \
+	"cmdallow all 1.2.3.0/24" \
+	"cmddeny 1.2.3.4" \
+	"cmddeny all 1.2.3.0/24" \
+	"cyclelogs" \
+	"delete 10.0.0.0" \
+	"delete ID#0000000001" \
+	"deny 1.2.3.4" \
+	"deny all 1.2.3.0/24" \
+	"dfreq 1.0e-3" \
+	"doffset -1.0" \
+	"dump" \
+	"local stratum 5 distance 1.0 orphan" \
+	"local off" \
+	"makestep 10.0 3" \
+	"makestep" \
+	"manual delete 0" \
+	"manual off" \
+	"manual on" \
+	"manual reset" \
+	"maxdelay 1.2.3.4 1e-2" \
+	"maxdelaydevratio 1.2.3.4 5.0" \
+	"maxdelayratio 1.2.3.4 3.0" \
+	"maxpoll 1.2.3.4 5" \
+	"maxupdateskew 1.2.3.4 10.0" \
+	"minpoll 1.2.3.4 3" \
+	"minstratum 1.2.3.4 1" \
+	"minstratum ID#0000000001 1" \
+	"ntpdata 1.2.3.4" \
+	"offline" \
+	"offline 255.255.255.0/1.2.3.0" \
+	"offline 1.2.3.0/24" \
+	"online" \
+	"online 1.2.3.0/24" \
+	"onoffline" \
+	"polltarget 1.2.3.4 10" \
+	"refresh" \
+	"rekey" \
+	"reload sources" \
+	"reselect" \
+	"reselectdist 1e-3" \
+	"reset sources" \
+	"selectdata" \
+	"selectopts 1.2.3.4 -noselect +trust +require +prefer" \
+	"selectopts ID#0000000001 +prefer" \
+	"selectopts PPS0 +prefer" \
+	"settime 16:30" \
+	"settime 16:30:05" \
+	"settime Nov 21, 2015 16:30:05" \
+	"serverstats" \
+	"shutdown" \
+	"smoothtime reset" \
+	"smoothtime activate" \
+	"trimrtc" \
+	"writertc"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "501 Not authorised$" || test_fail
+done
+
+cmdmon_unix=1
+
+chronyc_conf="
+authdata
+clients -k -p 2
+clients -r
+clients
+ntpdata
+selectdata
+serverstats"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+node1\.net1\.clk                 -     0    0    0    -    0    0    0    0
+Hostname                      NTP   Drop Int IntL Last  NTS-KE   Drop Int  Last
+===============================================================================
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+node1\.net1\.clk                  1      0   -   -     0       0      0   -     -
+Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+node1\.net1\.clk                  0      0   -   -     0       0      0   -     -
+
+Remote address  : 192\.168\.123\.1 \(C0A87B01\)
+Remote port     : 123
+Local address   : 192\.168\.123\.1 \(C0A87B01\)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 1
+Poll interval   : 6 \(64 seconds\)
+Precision       : -23 \(0\.000000119 seconds\)
+Root delay      : 0\.000000 seconds
+Root dispersion : 0\.000000 seconds
+Reference ID    : 7F7F0101 \(\)
+Reference time  : Thu Dec 31 23:59:5[89] 2009
+Offset          : [-+]0\.000...... seconds
+Peer delay      : 0\.00....... seconds
+Peer dispersion : 0\.00000.... seconds
+Response time   : 0\.000000... seconds
+Jitter asymmetry: \+0\.00
+NTP tests       : 111 111 1110
+Interleaved     : No
+Authenticated   : No
+TX timestamping : Kernel
+RX timestamping : Kernel
+Total TX        : 1
+Total RX        : 1
+Total valid RX  : 1
+Total good RX   : 0
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+M node1\.net1\.clk            N ----- -----    0   1\.0    \+0ns    \+0ns  N
+NTP packets received       : 1
+NTP packets dropped        : 0
+Command packets received   : 12
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 0
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 0
+Interleaved NTP packets    : 0
+NTP timestamps held        : 0
+NTP timestamp span         : 0
+NTP daemon RX timestamps   : 0
+NTP daemon TX timestamps   : 1
+NTP kernel RX timestamps   : 1
+NTP kernel TX timestamps   : 0
+NTP hardware RX timestamps : 0
+NTP hardware TX timestamps : 0$" || test_fail
+
+chronyc_conf="
+deny all
+cmdallow all
+allow 1.2.3.4
+allow 1.2.3.0/28
+deny 1.2.3.0/27
+allow 1.2.4.5
+deny all 1.2.4.0/27
+cmddeny 5.6.7.8
+cmdallow all 5.6.7.0/28
+accheck 1.2.3.4
+accheck 1.2.3.5
+accheck 1.2.4.5
+cmdaccheck 5.6.7.8"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+208 Access allowed
+209 Access denied
+209 Access denied
+208 Access allowed$" || test_fail
+
+if check_config_h 'FEAT_IPV6 1'; then
+	chronyc_conf="
+	deny all
+	cmdallow all
+	allow 2001:db8::1
+	allow 2001:db8::/64
+	deny 2001:db8::/63
+	allow 2001:db8:1::1
+	deny all 2001:db8:1::/63
+	cmddeny 2001:db9::1
+	cmdallow all 2001:db9::/64
+	accheck 2001:db8::1
+	accheck 2001:db8::2
+	accheck 2001:db8:1::1
+	cmdaccheck 2001:db9::1"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+
+	check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+208 Access allowed
+209 Access denied
+209 Access denied
+208 Access allowed$" || test_fail
+fi
+
+chronyc_conf="
+delete 192.168.123.1
+add server node1.net1.clk minpoll 6 maxpoll 10 iburst
+offline 192.168.123.1
+burst 1/1 192.168.123.1
+online 192.168.123.1
+maxdelay 192.168.123.1 1e-2
+maxdelaydevratio 192.168.123.1 5.0
+maxdelayratio 192.168.123.1 3.0
+maxpoll 192.168.123.1 5
+maxupdateskew 192.168.123.1 10.0
+minpoll 192.168.123.1 3
+minstratum 192.168.123.1 1
+polltarget 192.168.123.1 10
+selectopts 192.168.123.1 +trust +prefer -require
+selectdata
+selectopts 192.168.123.1 +noselect -prefer -trust +require
+selectdata
+delete 192.168.123.1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+M node1\.net1\.clk            N \-PT\-\- \-PT\-\-    0   1\.0    \+0ns    \+0ns  \?
+200 OK
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+M node1\.net1\.clk            N N\-\-R\- N\-\-R\-    0   1\.0    \+0ns    \+0ns  \?
+200 OK$" || test_fail
+
+chronyc_conf="
+cyclelogs
+dump
+dfreq 1.0e-3
+doffset -0.01
+local stratum 5 distance 1.0 orphan
+local off
+makestep 10.0 3
+makestep
+manual on
+settime now
+manual delete 0
+manual reset
+manual off
+onoffline
+refresh
+rekey
+reload sources
+reselect
+reselectdist 1e-3
+reset sources
+shutdown"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_chronyc_output "^200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+Clock was .\... seconds fast.  Frequency change = 0.00ppm, new frequency = 0.00ppm
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK
+200 OK$" || test_fail
+
+server_conf="
+server 192.168.123.1
+noclientlog"
+
+commands=(
+	"add server nosuchnode.net1.clk" "^Invalid host/IP address$"
+	"allow nosuchnode.net1.clk" "^Could not read address$"
+	"allow 192.168.123.0/2 4" "^Could not read address$"
+	"allow 192.168.123.0/2e" "^Could not read address$"
+	"allow 192.168.12e" "^Could not read address$"
+	"allow 192.168123" "^Could not read address$"
+	"allow 192.168.123.2/33" "^507 Bad subnet$"
+	"clients" "Hostname.*519 Client logging is not active in the daemon$"
+	"delete 192.168.123.2" "^503 No such source$"
+	"minpoll 192.168.123.2 5" "^503 No such source$"
+	"ntpdata 192.168.123.2" "^503 No such source$"
+	"settime now" "^505 Facility not enabled in daemon$"
+	"smoothing" "^505 Facility not enabled in daemon$"
+	"smoothtime activate" "^505 Facility not enabled in daemon$"
+	"smoothtime reset" "^505 Facility not enabled in daemon$"
+	"sourcename 192.168.123.2" "^503 No such source$"
+	"trimrtc" "^513 RTC driver not running$"
+	"writertc" "^513 RTC driver not running$"
+)
+
+for i in $(seq 0 $[${#commands[*]} / 2]); do
+	chronyc_conf=${commands[$[i * 2]]}
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "${commands[$[i * 2 + 1]]}" || test_fail
+done
+
+cmdmon_unix=0
+server_conf="server 192.168.123.1"
+
+chronyc_conf="dns -n
+dns +n
+dns -4
+dns -6
+dns -46
+timeout 200
+retries 1
+keygen
+keygen 10 MD5 128
+keygen 11 MD5 40
+help
+quit
+nosuchcommand"
+
+run_test || test_fail
+
+check_chronyc_output "^1 (MD5|SHA1) HEX:........................................
+10 MD5 HEX:................................
+11 MD5 HEX:....................
+System clock:.*this help
+ *$" || test_fail
+
+chronyc_conf="keygen 10 NOSUCHTYPE 128
+help"
+run_test || test_fail
+check_chronyc_output "^Unknown hash function or cipher NOSUCHTYPE\$" || test_fail
+
+if check_config_h 'FEAT_SECHASH 1'; then
+	for hash in MD5 SHA1 SHA256 SHA384 SHA512; do
+		chronyc_conf="keygen 5 $hash"
+		run_test || test_fail
+		check_chronyc_output "^5 $hash HEX:........................................\$" || test_fail
+	done
+fi
+
+if check_config_h 'HAVE_CMAC 1'; then
+	chronyc_conf="keygen 6 AES128
+keygen 7 AES256"
+	run_test || test_fail
+	check_chronyc_output "^6 AES128 HEX:................................
+7 AES256 HEX:................................................................\$" || test_fail
+fi
+
+# Pass every fourth request
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 (min (% (sum 1) 4) 1) 1)))
+EOF
+)
+limit=15
+
+chronyc_conf="sources"
+run_test || test_fail
+check_chronyc_output "^506 Cannot talk to daemon$" || test_fail
+
+chronyc_conf="retries 3
+sources"
+run_test || test_fail
+check_chronyc_output "^MS.*0ns$" || test_fail
+
+test_pass
diff --git a/test/simulation/111-knownclient b/test/simulation/111-knownclient
new file mode 100755
index 0000000..92bad54
--- /dev/null
+++ b/test/simulation/111-knownclient
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "reply to client configured as server"
+
+server_conf="server 192.168.123.2 noselect
+acquisitionport 123"
+client_conf="acquisitionport 123"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_port || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/112-port b/test/simulation/112-port
new file mode 100755
index 0000000..2f10eed
--- /dev/null
+++ b/test/simulation/112-port
@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "port and acquisitionport directives"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+# This check is expected to fail
+check_packet_port && test_fail
+
+client_conf="acquisitionport 123"
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_port || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_conf=""
+for server_conf in \
+	"port 0" \
+	"acquisitionport 123
+port 0"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_port || test_fail
+	check_packet_interval || test_fail
+	# These checks are expected to fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+done
+
+server_conf="port 124
+acquisitionport 123"
+client_server_options="port 124"
+for client_conf in \
+	"acquisitionport 0" \
+	"acquisitionport 123" \
+	"acquisitionport 124"
+do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+	# This check is expected to fail
+	check_packet_port && test_fail
+done
+
+test_pass
diff --git a/test/simulation/113-leapsecond b/test/simulation/113-leapsecond
new file mode 100755
index 0000000..394440b
--- /dev/null
+++ b/test/simulation/113-leapsecond
@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "leap second"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Dec 30 2008 0:00:00' +'%s')
+
+leap=$[2 * 24 * 3600]
+limit=$[4 * 24 * 3600]
+client_start=$[2 * 3600]
+server_conf="refclock SHM 0 dpoll 10 poll 10
+leapsectz right/UTC"
+refclock_jitter=1e-9
+refclock_offset="(* -1.0 (equal 0.1 (max (sum 1.0) $leap) $leap))"
+
+for leapmode in system step slew; do
+	client_conf="leapsecmode $leapmode"
+	if [ $leapmode = slew ]; then
+		max_sync_time=$[$leap + 12]
+	else
+		max_sync_time=$[$leap]
+	fi
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+client_server_options="trust"
+client_conf="refclock SHM 0 dpoll 10 poll 10 delay 1e-3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_server_options=""
+client_conf="leapsecmode system"
+min_sync_time=230000
+max_sync_time=240000
+
+for smoothmode in "" "leaponly"; do
+	server_conf="refclock SHM 0 dpoll 10 poll 10
+	leapsectz right/UTC
+	leapsecmode slew
+	smoothtime 400 0.001 $smoothmode"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/114-presend b/test/simulation/114-presend
new file mode 100755
index 0000000..19400ab
--- /dev/null
+++ b/test/simulation/114-presend
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "presend option"
+
+limit=9900
+min_sync_time=136
+max_sync_time=260
+client_server_options="presend 6 maxdelay 16"
+client_conf="maxdistance 10"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+base_delay=5
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/115-cmdmontime b/test/simulation/115-cmdmontime
new file mode 100755
index 0000000..525062d
--- /dev/null
+++ b/test/simulation/115-cmdmontime
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "cmdmon timestamps"
+
+# The following tests need 64-bit time_t
+check_config_h 'HAVE_LONG_TIME_T 1' || test_skip
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=2
+client_server_options="noselect"
+client_conf="local stratum 1"
+chronyc_start="1.5"
+chronyc_conf="tracking"
+
+for year in `seq 1850 100 2300`; do
+	export CLKNETSIM_START_DATE=$(date -d "Jan 01 00:00:05 $year UTC" +'%s')
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_chronyc_output "^.*Ref time \(UTC\).*Jan 01 00:00:0. $year.*$" || test_fail
+done
+
+test_pass
diff --git a/test/simulation/116-minsources b/test/simulation/116-minsources
new file mode 100755
index 0000000..f576423
--- /dev/null
+++ b/test/simulation/116-minsources
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "minsources directive"
+
+client_conf="minsources 3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+# These check are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+servers=3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/117-fallbackdrift b/test/simulation/117-fallbackdrift
new file mode 100755
index 0000000..21f6963
--- /dev/null
+++ b/test/simulation/117-fallbackdrift
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "fallback drift"
+
+limit=100000
+wander=0.0
+jitter=1e-6
+time_offset=10
+freq_offset="(* 1e-4 (sine 1000))"
+base_delay="(* -1.0 (equal 0.1 (min time 4250) 4250))"
+client_server_options="minpoll 4 maxpoll 4"
+client_conf="fallbackdrift 6 10"
+max_sync_time=4500
+time_max_limit=1e0
+time_rms_limit=1e0
+freq_max_limit=2e-4
+freq_rms_limit=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/118-maxdelay b/test/simulation/118-maxdelay
new file mode 100755
index 0000000..117b170
--- /dev/null
+++ b/test/simulation/118-maxdelay
@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "maxdelay options"
+
+max_sync_time=2000
+base_delay=1e-5
+jitter=1e-5
+wander=0.0
+freq_offset="(sum 1e-10)"
+time_rms_limit=2e-4
+
+client_server_options="maxpoll 6 maxdelay 3e-5 maxdelayratio 2.0 maxdelaydevratio 2.0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+for client_server_options in "maxpoll 6 maxdelay 2e-5"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_packet_interval || test_fail
+	check_sync && test_fail
+done
+
+min_sync_time=10
+client_conf="
+logdir tmp
+log rawmeasurements"
+client_server_options="minpoll 2 maxpoll 2 maxdelayquant 0.1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 200 500 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1101" 2000 2300 measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/119-smoothtime b/test/simulation/119-smoothtime
new file mode 100755
index 0000000..7f5114c
--- /dev/null
+++ b/test/simulation/119-smoothtime
@@ -0,0 +1,82 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "smoothtime option"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+server_strata=2
+server_conf="smoothtime 400 0.001"
+server_server_options="minpoll 8"
+min_sync_time=600
+max_sync_time=800
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+limit=10000
+refclock_jitter=1e-4
+refclock_offset="(* 10.0 (equal 0.1 (max (sum 1.0) 1000) 1000))"
+server_step="(* -10.0 (equal 0.1 (sum 1.0) 1))"
+server_strata=1
+server_conf="refclock SHM 0 dpoll 4 poll 6
+smoothtime 2000 1
+maxjitter 10.0"
+time_offset=-10
+server_server_options=""
+client_server_options="minpoll 6 maxpoll 6"
+client_conf="corrtimeratio 100"
+min_sync_time=8000
+max_sync_time=9000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_options="minpoll 6 maxpoll 6 xleave maxdelay 1e-1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_options="minpoll 6 maxpoll 6"
+min_sync_time=$default_min_sync_time
+max_sync_time=$default_max_sync_time
+time_max_limit=11
+time_rms_limit=11
+freq_max_limit=1e-2
+freq_rms_limit=2e-3
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+refclock_jitter=1e-9
+refclock_offset="(* 1e-1 (triangle 1000) (+ -1.0 (pulse 1000 10000)))"
+server_step=""
+server_conf="refclock SHM 0 dpoll 4 poll 6 minsamples 4 maxsamples 4
+smoothtime 1e4 1e-6"
+client_server_options="minpoll 4 maxpoll 4"
+time_offset=0.1
+jitter=1e-6
+wander=0.0
+min_sync_time=30
+max_sync_time=40
+time_max_limit=1e-5
+time_rms_limit=5e-6
+freq_max_limit=1e-6
+freq_rms_limit=1e-7
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/120-selectoptions b/test/simulation/120-selectoptions
new file mode 100755
index 0000000..611815e
--- /dev/null
+++ b/test/simulation/120-selectoptions
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "source selection options"
+
+servers=3
+falsetickers=2
+
+base_delay=0.6
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 trust"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 prefer"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+# This check is expected to fail
+check_sync && test_fail
+
+base_delay=1.1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+base_delay=1e-3
+falsetickers=1
+
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 require"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+client_server_conf="
+server 192.168.123.1 require
+server 192.168.123.2
+server 192.168.123.3"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+# These checks are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+cat > tmp/keys <<-EOF
+1 MD5 HEX:1B81CBF88D4A73F2E8CE59647F6E5C1719B6CAF5
+EOF
+
+server_conf="keyfile tmp/keys"
+client_server_conf="
+server 192.168.123.1 key 1
+server 192.168.123.2
+server 192.168.123.3"
+
+for authselectmode in require prefer mix ignore; do
+	client_conf="keyfile tmp/keys
+		     authselectmode $authselectmode"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	if [ $authselectmode = ignore ]; then
+		check_sync || test_fail
+	else
+		check_sync && test_fail
+	fi
+done
+
+test_pass
diff --git a/test/simulation/121-orphan b/test/simulation/121-orphan
new file mode 100755
index 0000000..7579997
--- /dev/null
+++ b/test/simulation/121-orphan
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "orphan option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+server_strata=3
+server_conf="local stratum 5 orphan
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3"
+max_sync_time=900
+client_start=140
+chronyc_start=700
+chronyc_conf="tracking"
+time_rms_limit=5e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^.*Stratum *: 7.*$" || test_fail
+
+test_pass
diff --git a/test/simulation/122-xleave b/test/simulation/122-xleave
new file mode 100755
index 0000000..c19063a
--- /dev/null
+++ b/test/simulation/122-xleave
@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "interleaved mode"
+
+client_server_options="xleave"
+client_conf="
+logdir tmp
+log rawmeasurements"
+
+server_conf="noclientlog"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 .111.* 4I [DKH] [DKH]\$" 0 0 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+server_conf=""
+max_sync_time=270
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 1111.* 4B [DKH] [DKH]\$" 2 2 measurements.log || test_fail
+check_file_messages "111 111 1111.* 4I [DKH] [DKH]\$" 30 200 measurements.log || test_fail
+check_file_messages "111 111 0111.* 4I [DKH] [DKH]\$" 1 1 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+clients=2
+peers=2
+max_sync_time=500
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 2) (equal 0.1 to 1)))"
+
+client_lpeer_options="xleave minpoll 5 maxpoll 5"
+client_rpeer_options="minpoll 5 maxpoll 5"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+# These checks are expected to fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+rm -f tmp/measurements.log
+
+for rpoll in 4 5 6; do
+	client_rpeer_options="xleave minpoll $rpoll maxpoll $rpoll"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	if [ $rpoll -le 5 ]; then
+		check_file_messages "111 111 1111.* 1B [DKH] [DKH]\$" 0 0 measurements.log || test_fail
+		check_file_messages "111 111 1111.* 1I [DKH] [DKH]\$" 200 310 measurements.log || test_fail
+	else
+		check_file_messages "111 111 1111.* 1B [DKH] [DKH]\$" 125 135 measurements.log || test_fail
+		check_file_messages "111 111 1111.* 1I [DKH] [DKH]\$" 20 30 measurements.log || test_fail
+	fi
+	rm -f tmp/measurements.log
+done
+
+if check_config_h 'FEAT_CMDMON 1'; then
+	# test client timestamp selection and server timestamp correction
+	base_delay="(+ 1.25e-6 (* -1 (equal 0.1 from 5)))"
+	jitter=1e-9
+	wander=1e-12
+	client_lpeer_options="xleave minpoll 5 maxpoll 5 noselect"
+	client_rpeer_options="xleave minpoll 5 maxpoll 5 noselect"
+	chronyc_conf="doffset -0.1"
+	chronyc_start=7200
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync && test_fail
+
+	check_file_messages "\.2   N  2 111 111 ....   5  5 .\... ..\....e-..  2\....e-06" \
+		290 310 measurements.log || test_fail
+	check_file_messages "\.2   N  2 111 111 ....   5  5 .\... ..\....e-..  .\....e-0[0123]" \
+		0 0 measurements.log || test_fail
+	rm -f tmp/measurements.log
+fi
+
+test_pass
diff --git a/test/simulation/123-mindelay b/test/simulation/123-mindelay
new file mode 100755
index 0000000..89a9f33
--- /dev/null
+++ b/test/simulation/123-mindelay
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "mindelay and asymmetry options"
+
+jitter_asymmetry=0.499
+time_rms_limit=1e-6
+time_freq_limit=1e-9
+wander=1e-12
+
+for client_server_options in "mindelay 2e-4 asymmetry 0.499"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_packet_interval || test_fail
+	check_sync || test_fail
+done
+
+for client_server_options in "mindelay 1e-4 asymmetry 0.499" "mindelay 2e-4 asymmetry 0.0"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync && test_fail
+done
+
+test_pass
diff --git a/test/simulation/124-tai b/test/simulation/124-tai
new file mode 100755
index 0000000..97064f7
--- /dev/null
+++ b/test/simulation/124-tai
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "tai option"
+
+check_config_h 'FEAT_REFCLOCK 1' || test_skip
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Dec 31 2008 23:50:00' +'%s')
+
+leap=$[10 * 60]
+limit=$[20 * 60]
+min_sync_time=2
+max_sync_time=15
+refclock_jitter=1e-6
+servers=0
+
+refclock_offset="(+ -34 (equal 0.1 (max (sum 1.0) $leap) $leap))"
+client_conf="
+refclock SHM 0 dpoll 0 poll 0 tai
+leapsectz right/UTC
+leapsecmode ignore
+maxchange 1e-3 1 0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+export CLKNETSIM_START_DATE=$(TZ=UTC date -d 'Jan 01 2009 00:10:00' +'%s')
+
+time_offset=-1000
+refclock_offset="(+ -34)"
+client_conf="
+refclock SHM 0 dpoll 0 poll 0 tai
+leapsectz right/UTC
+makestep 1 1
+maxchange 1e-3 1 0"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/125-packetloss b/test/simulation/125-packetloss
new file mode 100755
index 0000000..505e4fa
--- /dev/null
+++ b/test/simulation/125-packetloss
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "packet loss"
+
+# Drop 33% of packets by default and 100% on the 3->1 path
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1 (equal 0.33 (uniform) 1.0))
+     (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))
+EOF
+)
+clients=2
+peers=2
+jitter=1e-5
+limit=20000
+max_sync_time=10000
+
+for options in "maxpoll 8" "maxpoll 8 xleave"; do
+	client_server_options=$options
+	client_peer_options=$options
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_sync || test_fail
+done
+
+test_pass
diff --git a/test/simulation/126-burst b/test/simulation/126-burst
new file mode 100755
index 0000000..1cb6f9c
--- /dev/null
+++ b/test/simulation/126-burst
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "burst option"
+
+# Pass every fourth packet on the 2->1 path
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* -1
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (% (sum 1) 4) 1) 1)))
+EOF
+)
+
+client_server_options="burst polltarget 1"
+min_sync_time=700
+max_sync_time=730
+client_max_min_out_interval=2.2
+client_min_mean_out_interval=150.0
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+# Add a significant delay to 70% of packets on the 2->1 path after 6th packet
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4
+     (* 0.15
+        (equal 0.1 from 2)
+        (equal 0.1 to 1)
+        (equal 0.1 (min (sum 1) 7) 7)
+        (equal 0.7 (uniform) 0.0)))
+EOF
+)
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+
+test_pass
diff --git a/test/simulation/127-filter b/test/simulation/127-filter
new file mode 100755
index 0000000..739dd91
--- /dev/null
+++ b/test/simulation/127-filter
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "filter option"
+
+client_server_options="minpoll 4 maxpoll 4 filter 15 maxdelay 3.5e-4"
+min_sync_time=710
+max_sync_time=720
+client_max_min_out_interval=16.1
+client_min_mean_out_interval=15.9
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+base_delay="(+ 1e-4 (* -1 (equal 0.3 (uniform) 0.0)))"
+client_server_options="minpoll 4 maxpoll 4 filter 3"
+min_sync_time=130
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+limit=10
+client_server_options="minpoll -6 maxpoll -6 filter 1"
+
+base_delay=1e-4
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_file_messages "	2	1	" 590 640 log.packets || test_fail
+
+base_delay=2e-2
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_file_messages "	2	1	" 9 10 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/128-nocontrol b/test/simulation/128-nocontrol
new file mode 100755
index 0000000..3f0d18d
--- /dev/null
+++ b/test/simulation/128-nocontrol
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-x option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+wander=0.0
+time_offset=0.0
+freq_offset=0.0
+time_max_limit=1e-6
+freq_max_limit=1e-9
+min_sync_time=0
+max_sync_time=0
+client_chronyd_options="-x"
+chronyc_start=300
+chronyc_conf="tracking"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_chronyc_output "^.*Stratum *: 2.*$" || test_fail
+
+test_pass
diff --git a/test/simulation/129-reload b/test/simulation/129-reload
new file mode 100755
index 0000000..56bc3da
--- /dev/null
+++ b/test/simulation/129-reload
@@ -0,0 +1,109 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-r option"
+
+wander=0.0
+limit=100
+min_sync_time=100
+max_sync_time=104
+client_chronyd_options="-r"
+client_conf="dumpdir tmp
+maxupdateskew 10000"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_log_messages "Loaded dump file" 0 0 || test_fail
+check_file_messages "." 6 6 192.168.123.1.dat || test_fail
+
+client_start=$limit
+limit=1000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Loaded dump file" 1 1 || test_fail
+check_file_messages "." 10 30 192.168.123.1.dat || test_fail
+
+rm -f tmp/*.dat
+
+client_start=0
+limit=200
+jitter=1e-6
+client_conf="dumpdir tmp
+maxupdateskew 1e-6
+maxslewrate 1e-6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+
+check_log_messages "Loaded dump file" 0 0 || test_fail
+check_file_messages "." 8 8 192.168.123.1.dat || test_fail
+cp tmp/192.168.123.1.dat tmp/backup.dat
+
+client_start=$limit
+limit=1000
+min_sync_time=201
+max_sync_time=203
+client_server_options="offline"
+client_conf="dumpdir tmp"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Loaded dump file" 1 1 || test_fail
+check_file_messages "." 8 8 192.168.123.1.dat || test_fail
+
+cp -f tmp/backup.dat tmp/192.168.123.1.dat
+
+client_server_options="key 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync && test_fail
+
+check_log_messages "Could not load dump file" 1 1 || test_fail
+check_log_messages "Loaded dump file" 0 0 || test_fail
+
+client_server_options=""
+
+if check_config_h 'FEAT_REFCLOCK 1'; then
+	refclock_jitter=1e-6
+	servers=0
+	client_start=0
+	limit=40
+	min_sync_time=56
+	max_sync_time=58
+	client_chronyd_options="-r"
+	client_conf="dumpdir tmp
+	refclock SHM 0"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+
+	check_log_messages "Loaded dump file" 0 0 || test_fail
+	check_file_messages "." 6 6 refid:53484d30.dat || test_fail
+
+	client_start=$limit
+	limit=300
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_log_messages "Loaded dump file" 1 1 || test_fail
+	check_file_messages "." 6 23 refid:53484d30.dat || test_fail
+
+	rm -f tmp/*.dat
+fi
+
+test_pass
diff --git a/test/simulation/130-quit b/test/simulation/130-quit
new file mode 100755
index 0000000..da2b8cf
--- /dev/null
+++ b/test/simulation/130-quit
@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "-q/-Q option"
+
+wander=0.0
+freq_offset=0.0
+min_sync_time=5
+max_sync_time=10
+client_chronyd_options="-q"
+client_server_options="iburst"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+min_sync_time=1
+max_sync_time=1
+client_server_options="iburst maxsamples 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+client_chronyd_options="-Q"
+run_test || test_fail
+check_sync && test_fail
+
+test_pass
diff --git a/test/simulation/131-maxchange b/test/simulation/131-maxchange
new file mode 100755
index 0000000..59cc0c1
--- /dev/null
+++ b/test/simulation/131-maxchange
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "maxchange directive"
+
+time_offset=2
+max_sync_time=5000
+client_conf="maxchange 0.1 1 3"
+client_step="(* $step (equal 0.1 (sum 1.0) 300))"
+
+run_test || test_fail
+check_chronyd_exit && test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync && test_fail
+check_log_messages "seconds exceeds.*ignored" 3 3 || test_fail
+check_log_messages "seconds exceeds.*exiting" 1 1 || test_fail
+
+test_pass
diff --git a/test/simulation/132-logchange b/test/simulation/132-logchange
new file mode 100755
index 0000000..8ef570e
--- /dev/null
+++ b/test/simulation/132-logchange
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "logchange directive"
+
+time_offset=2
+min_sync_time=590
+max_sync_time=700
+client_server_options="maxsamples 6"
+client_conf="logchange 0.1"
+client_step="(* $step (equal 0.1 (sum 1.0) 300))"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+check_log_messages "clock wrong by" 3 8 || test_fail
+
+test_pass
diff --git a/test/simulation/133-hwtimestamp b/test/simulation/133-hwtimestamp
new file mode 100755
index 0000000..f02a010
--- /dev/null
+++ b/test/simulation/133-hwtimestamp
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "hwtimestamp directive"
+
+check_config_h 'HAVE_LINUX_TIMESTAMPING 1' || test_skip
+
+export CLKNETSIM_TIMESTAMPING=2
+export CLKNETSIM_PHC_DELAY=1e-6
+export CLKNETSIM_PHC_JITTER=1e-7
+export CLKNETSIM_PHC_JITTER_ASYM=0.4
+
+refclock_jitter=1e-8
+refclock_offset=10.0
+min_sync_time=4
+max_sync_time=20
+time_rms_limit=1e-7
+freq_rms_limit=3e-8
+jitter=1e-8
+freq_offset=1e-5
+limit=200
+server_conf="
+clockprecision 1e-9
+hwtimestamp eth0"
+client_server_options="minpoll 0 maxpoll 0 xleave"
+client_chronyd_options="-d"
+
+for client_conf in \
+		"hwtimestamp eth0 nocrossts
+		clockprecision 1e-9" \
+		"hwtimestamp eth0
+		clockprecision 1e-9
+		acquisitionport 123"; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	if check_config_h 'FEAT_DEBUG 1'; then
+		check_log_messages "Accepted reading" 0 2 || test_fail
+		check_log_messages "Combined .* readings" 190 220 || test_fail
+		check_log_messages "HW clock samples" 190 200 || test_fail
+		check_log_messages "HW clock reset" 0 0 || test_fail
+		check_log_messages "Missing TX timestamp" 1 1 || test_fail
+		check_log_messages "Received message.*tss=KH" 195 200 || test_fail
+		check_log_messages "Received error.*message.*tss=KH" 195 200 || test_fail
+		check_log_messages "Updated RX timestamp.*tss=1" 1 1 || test_fail
+		check_log_messages "Updated RX timestamp.*tss=2" 195 200 || test_fail
+		check_log_messages "Polling PHC" 195 220 || test_fail
+		if echo "$client_conf" | grep -q nocrossts; then
+			check_log_messages "update_tx_timestamp.*Updated" 180 200 || test_fail
+			check_log_messages "update_tx_timestamp.*Unacceptable" 0 13 || test_fail
+		else
+			check_log_messages "update_tx_timestamp.*Updated" 50 140 || test_fail
+			check_log_messages "update_tx_timestamp.*Unacceptable" 50 140 || test_fail
+		fi
+	fi
+done
+
+server_conf+="
+server 192.168.123.2 minpoll 1 maxpoll 1 noselect"
+
+for maxpoll in -1 0 1; do
+	client_conf="hwtimestamp eth0 minpoll -1 maxpoll $maxpoll nocrossts"
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	if check_config_h 'FEAT_DEBUG 1'; then
+		case $maxpoll in
+			-1)
+				check_log_messages "Polling PHC on eth0$" 360 380 || test_fail
+				check_log_messages "Polling PHC.*before" 3 25 || test_fail
+				;;
+			0)
+				check_log_messages "Polling PHC on eth0$" 8 45 || test_fail
+				check_log_messages "Polling PHC.*before" 150 190 || test_fail
+				;;
+			1)
+				check_log_messages "Polling PHC on eth0$" 1 1 || test_fail
+				check_log_messages "Polling PHC.*before" 194 199 || test_fail
+				;;
+		esac
+	fi
+done
+
+test_pass
diff --git a/test/simulation/134-log b/test/simulation/134-log
new file mode 100755
index 0000000..ab1ced2
--- /dev/null
+++ b/test/simulation/134-log
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "log directive"
+
+check_config_h 'FEAT_PHC 1' || test_skip
+
+refclock_jitter=$jitter
+client_server_options="maxpoll 6"
+client_conf="refclock PHC /dev/ptp0 dpoll 4 poll 6 noselect
+logbanner 10
+logdir tmp
+log tracking rawmeasurements measurements selection statistics rtc refclocks tempcomp
+tempcomp tmp/tempcomp 64 0.0 0.0 0.0 0.0"
+
+echo 0.0 > tmp/tempcomp
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "=============" 31 33 \
+	tracking.log measurements.log tempcomp.log || test_fail
+check_file_messages "20.*192\.168\.123\.1" 150 160 \
+	tracking.log measurements.log statistics.log || test_fail
+check_file_messages "20.*PHC0 * N " 300 320 selection.log || test_fail
+check_file_messages "20.*192\.168\.123\.1 *[M*]" 300 320 selection.log || test_fail
+check_file_messages "20.*PHC0" 150 160 statistics.log || test_fail
+check_file_messages "20.*PHC0" 750 800 refclocks.log || test_fail
+check_file_messages "20.* 0\.0000" 150 160 tempcomp.log || test_fail
+
+test_pass
diff --git a/test/simulation/135-ratelimit b/test/simulation/135-ratelimit
new file mode 100755
index 0000000..86c435d
--- /dev/null
+++ b/test/simulation/135-ratelimit
@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "ratelimit directive"
+
+server_conf="ratelimit interval 6 burst 2 leak 4"
+client_server_options="minpoll 3 maxpoll 3"
+min_sync_time=16
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "	2	1	" 1200 1300 log.packets || test_fail
+check_file_messages "	1	2	" 180 220 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/136-broadcast b/test/simulation/136-broadcast
new file mode 100755
index 0000000..1488c53
--- /dev/null
+++ b/test/simulation/136-broadcast
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "broadcast directive"
+
+server_conf="broadcast 64 192.168.123.255"
+client_server_options="offline"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval && test_fail
+
+check_file_messages "	1	2	" 150 160 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/137-pool b/test/simulation/137-pool
new file mode 100755
index 0000000..de8d77d
--- /dev/null
+++ b/test/simulation/137-pool
@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "pool directive"
+
+limit=500
+client_conf="logdir tmp
+log measurements"
+
+servers=3
+client_server_conf="pool nodes-1-2-3.net1.clk"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.1" 5 10 measurements.log || test_fail
+check_file_messages "20.*192.168.123.2" 5 10 measurements.log || test_fail
+check_file_messages "20.*192.168.123.3" 5 10 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+servers=6
+client_server_conf="pool nodes-1-2-3-4-5-6.net1.clk minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.*" 30 35 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+servers=6
+client_server_conf="pool nodes-1-2-3-4-5-6.net1.clk maxsources 2 minpoll 6 maxpoll 6"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.*" 15 17 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+test_pass
diff --git a/test/simulation/138-syncloop b/test/simulation/138-syncloop
new file mode 100755
index 0000000..2d3999e
--- /dev/null
+++ b/test/simulation/138-syncloop
@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "loop prevention"
+
+mkdir tmp/logdir1 tmp/logdir2
+
+server_conf="
+server 192.168.123.1
+server 192.168.123.2
+logdir tmp/logdir1
+log measurements"
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+logdir tmp/logdir2
+log measurements
+allow"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1110" 30 200 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1110" 30 200 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\...* 111 111 1111" 0 0 logdir1/measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1111" 30 200 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 111 1110" 0 0 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1110" 30 200 logdir2/measurements.log || test_fail
+check_file_messages "20.*123\.2.* 111 111 1111" 0 0 logdir1/measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/139-nts b/test/simulation/139-nts
new file mode 100755
index 0000000..f1d2de3
--- /dev/null
+++ b/test/simulation/139-nts
@@ -0,0 +1,316 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "NTP authentication with NTS"
+
+check_config_h 'FEAT_NTS 1' || test_skip
+certtool --help &> /dev/null || test_skip
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010' +'%s')
+
+for i in 1 2; do
+	cat > tmp/cert$i.cfg <<-EOF
+	cn = "node$i.net1.clk"
+	dns_name = "node$i.net1.clk"
+	ip_address = "192.168.123.$i"
+	serial = 001
+	activation_date = "2010-01-01 00:00:00 UTC"
+	expiration_date = "2010-01-02 00:00:00 UTC"
+	signing_key
+	encryption_key
+	EOF
+
+	certtool --generate-privkey --key-type=ed25519 --outfile tmp/server$i.key &> \
+		tmp/log.certtool$i
+	certtool --generate-self-signed --load-privkey tmp/server$i.key \
+		--template tmp/cert$i.cfg --outfile tmp/server$i.crt &>> tmp/log.certtool$i
+done
+
+max_sync_time=400
+dns=1
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 66
+ntsdumpdir tmp
+"
+client_server_options="minpoll 6 maxpoll 6 nts"
+client_conf="
+nosystemcert
+ntstrustedcerts /dev/null
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts /dev/null
+logdir tmp
+log rawmeasurements"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 75 80 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 37 39 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 260 300 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+rm -f tmp/measurements.log
+
+client_conf+="
+ntsrefresh 120
+ntsdumpdir tmp"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 99 103 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 0 0 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 350 390 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+check_file_messages "." 12 13 192.168.123.1.nts || test_fail
+rm -f tmp/measurements.log
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010 + 40000 sec' +'%s')
+
+server_conf+="
+ntsrotate 100000"
+client_conf+="
+ntsrefresh 39500"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*123\.1.* 111 111 1111" 150 160 measurements.log || test_fail
+check_file_messages "20.*123\.1.* 111 001 0000" 0 0 measurements.log || test_fail
+check_file_messages "	2	1	.*	4460	" 6 10 log.packets || test_fail
+check_file_messages "^9\.......e+03	2	1	.*	4460	" 6 10 log.packets || test_fail
+check_file_messages "." 6 6 ntskeys || test_fail
+check_file_messages "." 12 13 192.168.123.1.nts || test_fail
+rm -f tmp/measurements.log
+
+client_conf="
+nosystemcert"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	2	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	2	1	.*	4460	" 10 20 log.packets || test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  2 00:00:01 UTC 2010' +'%s')
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	2	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	2	1	.*	4460	" 10 20 log.packets || test_fail
+check_log_messages "expired certificate" 4 4 || test_fail
+
+client_conf+="
+nocerttimecheck 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010' +'%s')
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntsrefresh 500"
+
+for dns in 1 0; do
+	server_conf="
+	ntsserverkey tmp/server1.key
+	ntsservercert tmp/server1.crt
+	ntsprocesses 0
+	ntsrotate 0
+	ntsdumpdir tmp"
+
+	if [ $dns != 0 ]; then
+		server_conf+="
+		ntsntpserver node2.net1.clk"
+		client_server_conf="server node1.net1.clk $client_server_options"
+	else
+		server_conf+="
+		ntsntpserver 192.168.123.2"
+		client_server_conf="server 192.168.123.1 $client_server_options"
+	fi
+
+	servers=1
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection && test_fail
+	check_sync && test_fail
+
+	check_file_messages "	2	1	.*	4460	" 45 100 log.packets || test_fail
+	check_file_messages "	2	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 4 10 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 3 10 || test_fail
+
+	servers=2
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_file_messages "	3	1	.*	4460	" 100 150 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 1 1 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 0 0 || test_fail
+
+	server_conf+="
+	ntsratelimit interval 12 burst 1 leak 4"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection && test_fail
+
+	check_file_messages "	3	1	.*	4460	1	0	2" 25 50 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+	check_log_messages "Source 192.168.123.1 changed to 192.168.123.2" 2 6 || test_fail
+	check_log_messages "Source 192.168.123.2 replaced with 192.168.123.1" 1 6 || test_fail
+done
+
+servers=2
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 0
+ntsntpserver node2.net1.clk
+port 11123
+ntsdumpdir tmp"
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntsdumpdir tmp"
+client_server_conf="server 192.168.123.1 $client_server_options"
+
+rm -f tmp/*.nts
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_log_messages "Could not change" 0 0 || test_fail
+check_file_messages "	3	1	.*	4460	1	0	2" 1 1 log.packets || test_fail
+check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+
+for dns in 1 0; do
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+
+	check_log_messages "Could not change" 0 0 || test_fail
+	check_file_messages "	3	1	.*	4460	1	0	2" 0 0 log.packets || test_fail
+	check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+done
+
+min_sync_time=$[default_min_sync_time + 200]
+max_sync_time=600
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsprocesses 0
+ntsrotate 0
+ntsdumpdir tmp"
+
+head -n 8 tmp/192.168.123.1.nts > tmp/192.168.123.1.nts_
+mv tmp/192.168.123.1.nts_ tmp/192.168.123.1.nts
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_log_messages "Could not change" 0 0 || test_fail
+check_file_messages "	3	1	.*	4460	1	0	2" 1 1 log.packets || test_fail
+check_file_messages "	3	2	.*	4460	" 0 0 log.packets || test_fail
+check_file_messages "	3	1	.*	11123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	11123	" 3 3 log.packets || test_fail
+
+dns=1
+min_sync_time=$default_min_sync_time
+max_sync_time=400
+server_conf="
+ntsserverkey tmp/server1.key
+ntsservercert tmp/server1.crt
+ntsserverkey tmp/server2.key
+ntsservercert tmp/server2.crt
+ntsprocesses 0"
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts tmp/server2.crt
+minsources 2"
+client_server_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/server1.crt
+ntstrustedcerts 1 tmp/server1.crt
+ntstrustedcerts 2 tmp/server2.crt
+ntstrustedcerts 3 tmp/server2.crt"
+client_server_conf="
+server node1.net1.clk $client_server_options certset 0
+server node2.net1.clk $client_server_options certset 2"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "	3	1	.*	123	" 100 200 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 100 200 log.packets || test_fail
+
+client_server_conf="
+server node1.net1.clk $client_server_options certset 2
+server node2.net1.clk $client_server_options"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	3	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+
+client_conf="
+nosystemcert
+ntstrustedcerts tmp/nosuch.crt
+ntstrustedcerts 2 tmp/nosuch.crt"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_sync && test_fail
+
+check_file_messages "	3	1	.*	123	" 0 0 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/140-noclientlog b/test/simulation/140-noclientlog
new file mode 100755
index 0000000..502398f
--- /dev/null
+++ b/test/simulation/140-noclientlog
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "noclientlog option"
+
+server_conf="noclientlog"
+client_server_options="xleave"
+client_conf="
+logdir tmp
+log rawmeasurements"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "111 111 1111.* 4B " 30 200 measurements.log || test_fail
+check_file_messages "111 111 1111.* 4I " 0 0 measurements.log || test_fail
+
+test_pass
diff --git a/test/simulation/141-copy b/test/simulation/141-copy
new file mode 100755
index 0000000..80e56bc
--- /dev/null
+++ b/test/simulation/141-copy
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "copy option"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+client_server_options="copy"
+chronyc_conf="tracking"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^Reference ID *: 7F7F0101 \(192\.168\.123\.1\)
+Stratum *: 1" || test_fail
+
+test_pass
diff --git a/test/simulation/142-ptpport b/test/simulation/142-ptpport
new file mode 100755
index 0000000..060932c
--- /dev/null
+++ b/test/simulation/142-ptpport
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "PTP port"
+
+# Block communication between 3 and 1
+base_delay="(+ 1e-4 (* -1 (equal 0.1 from 3) (equal 0.1 to 1)))"
+
+cat > tmp/peer.keys <<-EOF
+1 MD5 1234567890
+EOF
+
+clients=2
+peers=2
+max_sync_time=420
+
+server_conf="
+ptpport 319"
+client_conf="
+ptpport 319
+authselectmode ignore
+keyfile tmp/peer.keys"
+client_server_options="minpoll 6 maxpoll 6 port 319"
+client_peer_options="minpoll 6 maxpoll 6 port 319 key 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+check_file_messages "	2	1	.*	319	319	1	96	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	1	2	.*	319	319	1	96	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	2	3	.*	319	319	1	116	" 150 160 \
+	log.packets || test_fail
+check_file_messages "	3	2	.*	319	319	1	116	" 150 160 \
+	log.packets || test_fail
+
+test_pass
diff --git a/test/simulation/143-manual b/test/simulation/143-manual
new file mode 100755
index 0000000..618cee6
--- /dev/null
+++ b/test/simulation/143-manual
@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+export TZ=UTC
+
+test_start "manual input"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+limit=$[12 * 3600]
+client_server_conf=" "
+client_conf="manual"
+chronyc_conf="timeout 4000000
+settime 1:00:00
+settime 2:00:00
+settime 3:00:00
+settime 4:00:00
+manual delete 2
+settime 6:00:00
+manual list
+settime 8:00:00
+manual reset
+settime 10:00:00
+manual list"
+chronyc_start=1800
+base_delay=1800
+jitter=1e-6
+
+time_max_limit=4e-3
+freq_max_limit=4e-3
+time_rms_limit=2e-3
+freq_rms_limit=2e-5
+min_sync_time=7204
+max_sync_time=7206
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_sync || test_fail
+
+check_chronyc_output "^200 OK
+Clock was 0\.4. seconds fast\.  Frequency change = 0\.00ppm, new frequency = 0\.00ppm
+200 OK
+Clock was 0\.3. seconds fast\.  Frequency change = (99|100)\...ppm, new frequency = (99|100)\...ppm
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[01].ppm, new frequency = (99|100)\...ppm
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[01].ppm, new frequency = (99|100)\...ppm
+200 OK
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[012].ppm, new frequency = (99|100)\...ppm
+210 n_samples = 4
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0 2010-01-01 (00:59:59|01:00:00)      [- ]0\.00       0\.46      [- ]0\.00
+ 1 2010-01-01 (01:59:59|02:00:00)      [- ]0\.00       0\.36      [- ]0\.00
+ 2 2010-01-01 (03:59:59|04:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00
+ 3 2010-01-01 (05:59:59|06:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.[012].ppm, new frequency = (99|100)\...ppm
+200 OK
+200 OK
+Clock was \-?0\.0. seconds fast\.  Frequency change = \-?0\.00ppm, new frequency = (99|100)\...ppm
+210 n_samples = 1
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0 2010-01-01 (09:59:59|10:00:00)      [- ]0\.00      [- ]0\.00      [- ]0\.00$" \
+	|| test_fail
+
+test_pass
diff --git a/test/simulation/144-exp1 b/test/simulation/144-exp1
new file mode 100755
index 0000000..4a2042d
--- /dev/null
+++ b/test/simulation/144-exp1
@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "experimental extension field"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+primary_time_offset=0.1
+server_strata=4
+min_sync_time=2000
+max_sync_time=2300
+chronyc_conf="doffset 0.1"
+chronyc_options="-h /clknetsim/unix/1:1"
+chronyc_start=2000
+
+for options in "extfield F323" "xleave extfield F323"; do
+	client_server_options="minpoll 6 maxpoll 6 $options"
+	server_server_options="$client_server_options"
+
+	run_test || test_fail
+	check_chronyd_exit || test_fail
+	check_source_selection || test_fail
+	check_sync || test_fail
+done
+
+server_server_options=""
+server_strata=1
+clients=4
+peers=4
+max_sync_time=2400
+# chain of peers and one enabled chronyc
+base_delay=$(cat <<-EOF | tr -d '\n'
+  (+ 1e-4 -1
+     (equal 0.1 from (+ to 1))
+     (equal 0.1 from (+ to -1))
+     (equal 0.1 from 6)
+     (equal 0.1 to 6))
+EOF
+)
+
+for lpoll in 5 6 7; do
+	for options in "minsamples 16 extfield F323" "minsamples 16 xleave extfield F323"; do
+		client_lpeer_options="minpoll $lpoll maxpoll $lpoll $options"
+		client_rpeer_options="minpoll 6 maxpoll 6 $options"
+		client_server_options="$client_rpeer_options"
+
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_source_selection || test_fail
+		check_sync || test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/145-rtc b/test/simulation/145-rtc
new file mode 100755
index 0000000..22b62d9
--- /dev/null
+++ b/test/simulation/145-rtc
@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+
+. ./test.common
+test_start "RTC tracking"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+check_config_h 'FEAT_RTC 1' || test_skip
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  1 00:00:00 UTC 2010' +'%s')
+export CLKNETSIM_RTC_OFFSET=-10.0
+
+time_offset=$(awk "BEGIN {print -($freq_offset * $limit)}")
+wander=0.0
+chronyc_start=9900
+chronyc_conf="rtcdata"
+client_chronyd_options="-x"
+
+client_conf="
+hwclockfile /dev/null
+driftfile tmp/drift
+rtcfile tmp/rtc
+rtconutc"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_chronyc_output "^RTC ref time \(UTC\) : Fri Jan 01 02:4[34]:.. 2010
+Number of samples  : [0-9]+
+Number of runs     : [0-9]+
+Sample span period : [ 0-9]+
+RTC is fast by     :    -9\.01.... seconds
+RTC gains time at  :    99\.9[98]. ppm$" \
+|| test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan  5 00:00:00 UTC 2010' +'%s')
+export CLKNETSIM_RTC_OFFSET=$(awk "BEGIN {print -(10.0 - 4 * 86400 * $freq_offset)}")
+touch -d 'Jan  1 00:00:00 UTC 2010' tmp/drift
+
+time_offset=10
+min_sync_time=2
+max_sync_time=12
+time_max_limit=1e-2
+freq_max_limit=1e-1
+time_rms_limit=1e-3
+freq_rms_limit=1e-3
+client_chronyd_options="-s"
+client_conf+="
+rtcautotrim 1"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+check_chronyc_output "^RTC ref time \(UTC\) : Tue Jan 05 02:4[34]:.. 2010
+Number of samples  : [0-9]+
+Number of runs     : [0-9]+
+Sample span period : [ 0-9]+
+RTC is fast by     :     0\.1..... seconds
+RTC gains time at  :    [- ]0\.0.. ppm$" \
+|| test_fail
+
+export CLKNETSIM_START_DATE=$(date -d 'Jan 10 00:00:00 UTC 2010' +'%s')
+export CLKNETSIM_RTC_OFFSET=-10.0
+touch -d 'Jan 10 00:00:00 UTC 2010' tmp/drift
+
+time_offset=-10000
+min_sync_time=1
+max_sync_time=1
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/146-offline b/test/simulation/146-offline
new file mode 100755
index 0000000..f110a12
--- /dev/null
+++ b/test/simulation/146-offline
@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "online/offline switching"
+
+check_config_h 'FEAT_CMDMON 1' || test_skip
+
+servers=2
+limit=$[10 * 1800]
+client_server_conf="
+server 192.168.123.1 offline iburst
+server 192.168.123.2 polltarget 64"
+chronyc_conf="timeout 4000000
+activity
+offline
+activity
+onoffline 192.168.123.1
+online 192.168.123.2
+activity
+offline
+activity
+"
+chronyc_start=1
+base_delay="(+ 1e-4 (* 1800 (equal 0.1 from 4)))"
+jitter=1e-6
+
+time_max_limit=2e-2
+freq_max_limit=1e-3
+time_rms_limit=2e-2
+freq_rms_limit=1e-5
+min_sync_time=120
+max_sync_time=140
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "	3	1	.*	123	" 30 90 log.packets || test_fail
+check_file_messages "	3	2	.*	123	" 130 150 log.packets || test_fail
+
+check_chronyc_output "^200 OK
+1 sources online
+1 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address
+200 OK
+200 OK
+0 sources online
+2 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address
+200 OK
+200 OK
+200 OK
+2 sources online
+0 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address
+200 OK
+200 OK
+0 sources online
+2 sources offline
+0 sources doing burst \(return to online\)
+0 sources doing burst \(return to offline\)
+0 sources with unknown address" \
+	|| test_fail
+
+test_pass
diff --git a/test/simulation/147-refresh b/test/simulation/147-refresh
new file mode 100755
index 0000000..ea091e6
--- /dev/null
+++ b/test/simulation/147-refresh
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "address refreshment"
+
+limit=1000
+servers=5
+client_conf="logdir tmp
+log measurements"
+client_server_conf="server nodes-1-2.net1.clk maxpoll 6
+pool nodes-3-4-5.net1.clk maxpoll 6 maxsources 2"
+client_chronyd_options="-d"
+chronyc_conf="refresh"
+chronyc_start=500
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.1" 0 0 measurements.log || test_fail
+check_file_messages "20.*192.168.123.2" 15 17 measurements.log || test_fail
+check_file_messages "20.*192.168.123.[345]" 31 33 measurements.log || test_fail
+rm -f tmp/measurements.log
+if check_config_h 'FEAT_DEBUG 1'; then
+	check_log_messages "refreshing 192.168.123" 3 3 || test_fail
+	check_log_messages "resolved_name.*still fresh" 3 3 || test_fail
+fi
+
+limit=1100
+client_server_conf="
+server nodes-1-2.net1.clk maxpoll 6
+pool nodes-3-4-5.net1.clk maxpoll 6 maxsources 3"
+client_conf+="
+refresh 128"
+chronyc_conf=""
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_file_messages "20.*192.168.123.1" 0 0 measurements.log || test_fail
+check_file_messages "20.*192.168.123.2" 16 18 measurements.log || test_fail
+check_file_messages "20.*192.168.123.[345]" 50 55 measurements.log || test_fail
+rm -f tmp/measurements.log
+if check_config_h 'FEAT_DEBUG 1'; then
+	check_log_messages "refreshing 192.168.123" 8 8 || test_fail
+	check_log_messages "resolved_name.*still fresh" 8 8 || test_fail
+	check_log_messages "refreshing 192.168.123.2" 2 2 || test_fail
+	check_log_messages "refreshing 192.168.123.3" 2 2 || test_fail
+	check_log_messages "refreshing 192.168.123.4" 2 2 || test_fail
+	check_log_messages "refreshing 192.168.123.5" 2 2 || test_fail
+fi
+
+test_pass
diff --git a/test/simulation/148-replacement b/test/simulation/148-replacement
new file mode 100755
index 0000000..f15fc4d
--- /dev/null
+++ b/test/simulation/148-replacement
@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "source replacement"
+
+limit=5000
+client_conf="logdir tmp
+log measurements"
+
+servers=6
+falsetickers=2
+client_server_conf="pool nodes-1-2-3-4-5-6.net1.clk maxsources 5 polltarget 1 iburst"
+wander=1e-12
+jitter=1e-6
+min_sync_time=7
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Detected falseticker" 2 10 || test_fail
+check_log_messages "Source 192.168.123.. replaced with" 1 3 || test_fail
+check_file_messages "20.*192.168.123.* 11.1   6  6 " 15 18 measurements.log || test_fail
+check_file_messages "20.*00:[1-5].:.. 192.168.123.* 11.1   6  6 " 1 4 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+# 1 unreplaceable falseticker against 2 replaceable unreachable servers
+servers=5
+falsetickers=1
+limit=200000
+base_delay="(+ 1e-4 (* -1 (equal 0.6 to 4.5)))"
+client_conf+="
+minsources 2"
+client_server_conf="
+server 192.168.123.1
+server nodes-2-4.net1.clk
+server nodes-3-5.net1.clk"
+max_sync_time=150000
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Detected falseticker" 2 10 || test_fail
+check_log_messages "Source 192.168.123.. replaced with" 2 70 || test_fail
+check_log_messages "2010-01-01T0[0-4]:.*Source 192.168.123.. replaced with" 2 15 || test_fail
+check_log_messages "2010-01-01T0[5-9]:.*Source 192.168.123.. replaced with" 0 15 || test_fail
+check_file_messages "20.*192.168.123.* 11.1   6  6 " 20 500 measurements.log || test_fail
+rm -f tmp/measurements.log
+
+test_pass
diff --git a/test/simulation/201-freqaccumulation b/test/simulation/201-freqaccumulation
new file mode 100755
index 0000000..6f14246
--- /dev/null
+++ b/test/simulation/201-freqaccumulation
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+# Test fix in commit 60d0fa299307076143da94d36deb7b908fa9bdb7
+
+test_start "frequency accumulation"
+
+time_offset=100.0
+jitter=1e-6
+base_delay=1e-6
+wander=0.0
+
+limit=180
+time_max_limit=1e-5
+freq_max_limit=1e-7
+time_rms_limit=1e-5
+freq_rms_limit=1e-7
+min_sync_time=120
+max_sync_time=140
+
+client_server_options="minpoll 6 maxpoll 6"
+client_conf="driftfile tmp/drift
+makestep 1 1"
+
+for freq_offset in -5e-2 -5e-4 5e-4 5e-2; do
+	for drift in -1e+4 -1e+2 1e+2 1e+4; do
+		echo "$drift 100000" > tmp/drift
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		check_sync || test_fail
+	done
+done
+
+test_pass
diff --git a/test/simulation/202-prefer b/test/simulation/202-prefer
new file mode 100755
index 0000000..207c800
--- /dev/null
+++ b/test/simulation/202-prefer
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+# Test fix in commit 4253075a97141edfa62043ab71bd0673587e6629
+
+test_start "prefer option"
+
+servers=3
+client_server_conf="
+server 192.168.123.1
+server 192.168.123.2
+server 192.168.123.3 prefer"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection || test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+test_pass
diff --git a/test/simulation/README b/test/simulation/README
new file mode 100644
index 0000000..e174500
--- /dev/null
+++ b/test/simulation/README
@@ -0,0 +1,11 @@
+This is a collection of simulation tests using the clknetsim simulator
+(supported on Linux only).
+
+https://github.com/mlichvar/clknetsim
+
+The CLKNETSIM_PATH environment variable should point to the directory where
+clknetsim was downloaded and compiled. If the variable is not set, the tests
+will look for clknetsim in ./clknetsim in the current directory.
+
+The tests are written in bash and they can be run directly. The ./run script
+runs all tests.
diff --git a/test/simulation/run b/test/simulation/run
new file mode 100755
index 0000000..0954438
--- /dev/null
+++ b/test/simulation/run
@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+
+print_help() {
+	echo "$1 [-a] [-i ITERATIONS] [-m MAXFAILS] [-s SEED] [TEST]..."
+}
+
+run_test() {
+	local result name=$1 seed=$2
+
+	CLKNETSIM_RANDOM_SEED=$seed ./$name
+	result=$?
+
+	if [ $result -ne 0 -a $result -ne 9 ]; then
+		if [ $abort_on_fail -ne 0 ]; then
+			echo 1>&2
+			echo Failed with random seed $seed 1>&2
+			exit 1
+		fi
+		failed_seeds=(${failed_seeds[@]} $seed)
+	fi
+
+	return $result
+}
+
+abort_on_fail=0
+iterations=1
+max_fails=0
+random_seed=${CLKNETSIM_RANDOM_SEED:-$RANDOM}
+
+while getopts ":ai:m:s:" opt; do
+	case $opt in
+		a) abort_on_fail=1;;
+		i) iterations=$OPTARG;;
+		m) max_fails=$OPTARG;;
+		s) random_seed=$OPTARG;;
+		*) print_help "$0"; exit 3;;
+	esac
+done
+
+shift $[$OPTIND - 1]
+
+passed=() failed=() skipped=() failed_seeds=()
+
+[ $# -gt 0 ] && tests=($@) || tests=([0-9]*-*[^_])
+
+for test in "${tests[@]}"; do
+	if [ $iterations -gt 1 ]; then
+		printf "%-30s" "$test"
+		fails=0
+		for i in $(seq 1 $iterations); do
+			run_test $test $[$random_seed + $i - 1] > /dev/null
+			case $? in
+				0) echo -n ".";;
+				9) break;;
+				*) echo -n "x"; fails=$[$fails + 1];;
+			esac
+		done
+		if [ $i -lt $iterations ]; then
+			printf "%${iterations}s" ""
+			echo " SKIP"
+			result=9
+		elif [ $fails -gt $max_fails ]; then
+			echo " FAIL"
+			result=1
+		else
+			echo " PASS"
+			result=0
+		fi
+	else
+		printf "%s   " "$test"
+		run_test $test $random_seed
+		result=$?
+		echo
+	fi
+
+	case $result in
+		0) passed=(${passed[@]} $test);;
+		9) skipped=(${skipped[@]} $test);;
+		*) failed=(${failed[@]} $test);;
+	esac
+done
+
+echo
+echo "SUMMARY:"
+echo "  TOTAL  $[${#passed[@]} + ${#failed[@]} + ${#skipped[@]}]"
+echo "  PASSED ${#passed[@]}"
+echo "  FAILED ${#failed[@]}    (${failed[@]}) (${failed_seeds[@]})"
+echo "  SKIPPED ${#skipped[@]}   (${skipped[@]})"
+
+[ ${#failed[@]} -eq 0 ]
diff --git a/test/simulation/test.common b/test/simulation/test.common
new file mode 100644
index 0000000..3f6e80b
--- /dev/null
+++ b/test/simulation/test.common
@@ -0,0 +1,534 @@
+# Copyright (C) 2013-2014  Miroslav Lichvar <mlichvar@redhat.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+export LC_ALL=C
+export PATH=../../:$PATH
+export CLKNETSIM_PATH=${CLKNETSIM_PATH:-clknetsim}
+
+if [ ! -x $CLKNETSIM_PATH/clknetsim ]; then
+	echo "SKIP (clknetsim not found)"
+	exit 9
+fi
+
+. $CLKNETSIM_PATH/clknetsim.bash
+
+# Default test testings
+
+default_limit=10000
+default_primary_time_offset=0.0
+default_time_offset=1e-1
+default_freq_offset=1e-4
+default_base_delay=1e-4
+default_jitter=1e-4
+default_jitter_asymmetry=0.0
+default_wander=1e-9
+default_refclock_jitter=""
+default_refclock_offset=0.0
+
+default_update_interval=0
+default_shift_pll=2
+
+default_server_strata=1
+default_servers=1
+default_clients=1
+default_peers=0
+default_falsetickers=0
+default_server_start=0.0
+default_client_start=0.0
+default_chronyc_start=1000.0
+default_server_step=""
+default_client_step=""
+
+default_client_server_conf=""
+default_server_server_options=""
+default_client_server_options=""
+default_server_peer_options=""
+default_server_lpeer_options=""
+default_server_rpeer_options=""
+default_client_peer_options=""
+default_client_lpeer_options=""
+default_client_rpeer_options=""
+default_server_conf=""
+default_client_conf=""
+default_chronyc_conf=""
+default_server_chronyd_options=""
+default_client_chronyd_options=""
+default_chronyc_options=""
+
+default_time_max_limit=1e-3
+default_freq_max_limit=5e-4
+default_time_rms_limit=3e-4
+default_freq_rms_limit=1e-5
+default_min_sync_time=120
+default_max_sync_time=210
+
+default_client_min_mean_out_interval=0.0
+default_client_max_min_out_interval=inf
+
+default_cmdmon_unix=1
+default_pcap_dumps=0
+default_dns=0
+
+# Initialize test settings from their defaults
+for defoptname in ${!default_*}; do
+	optname=${defoptname#default_}
+	[ -z "${!optname}" ] && declare "$optname"="${!defoptname}"
+done
+
+test_start() {
+	rm -rf tmp/*
+	echo "Testing $@:"
+
+	check_config_h 'FEAT_NTP 1' || test_skip
+}
+
+test_pass() {
+	echo "PASS"
+	exit 0
+}
+
+test_fail() {
+	echo "FAIL"
+	exit 1
+}
+
+test_skip() {
+	echo "SKIP"
+	exit 9
+}
+
+test_ok() {
+	pad_line
+	echo -e "\tOK"
+	return 0
+}
+
+test_bad() {
+	pad_line
+	echo -e "\tBAD"
+	return 1
+}
+
+test_error() {
+	pad_line
+	echo -e "\tERROR"
+	return 1
+}
+
+msg_length=0
+pad_line() {
+	local line_length=56
+	[ $msg_length -lt $line_length ] && \
+		printf "%$[$line_length - $msg_length]s" ""
+	msg_length=0
+}
+
+# Print aligned message
+test_message() {
+	local level=$1 eol=$2
+	shift 2
+	local msg="$*"
+
+	while [ $level -gt 0 ]; do
+		echo -n "  "
+		level=$[$level - 1]
+		msg_length=$[$msg_length + 2]
+	done
+	echo -n "$msg"
+
+	msg_length=$[$msg_length + ${#msg}]
+	if [ $eol -ne 0 ]; then
+		echo
+		msg_length=0
+	fi
+}
+
+get_wander_expr() {
+	local scaled_wander
+
+	scaled_wander=$(awk "BEGIN {print $wander / \
+		sqrt($update_interval < 0 ? 2^-($update_interval) : 1)}")
+
+	echo "(+ $freq_offset (sum (* $scaled_wander (normal))))"
+}
+
+
+get_delay_expr() {
+	local direction=$1 asym
+
+	if [ $jitter_asymmetry == "0.0" ]; then
+		asym=""
+	elif [ $direction = "up" ]; then
+		asym=$(awk "BEGIN {print 1 - 2 * $jitter_asymmetry}")
+	elif [ $direction = "down" ]; then
+		asym=$(awk "BEGIN {print 1 + 2 * $jitter_asymmetry}")
+	fi
+	echo "(+ $base_delay (* $asym $jitter (exponential)))"
+}
+
+get_refclock_expr() {
+	echo "(+ $refclock_offset (* $refclock_jitter (normal)))"
+}
+
+get_chronyd_nodes() {
+	echo $[$servers * $server_strata + $clients]
+}
+
+get_node_name() {
+	local index=$1
+
+	if [ $dns -ne 0 ]; then
+		echo "node$index.net1.clk"
+	else
+		echo "192.168.123.$index"
+	fi
+}
+
+get_chronyd_conf() {
+	local i stratum=$1 peer=$2
+
+	if [ $stratum -eq 1 ]; then
+		echo "local stratum 1"
+		echo "$server_conf"
+	elif [ $stratum -le $server_strata ]; then
+		for i in $(seq 1 $servers); do
+			echo "server $(get_node_name $[$servers * ($stratum - 2) + $i]) $server_server_options"
+		done
+		for i in $(seq 1 $peers); do
+			[ $i -eq $peer -o $i -gt $servers ] && continue
+			echo -n "peer $(get_node_name $[$servers * ($stratum - 1) + $i]) $server_peer_options "
+			[ $i -lt $peer ] && echo "$server_lpeer_options" || echo "$server_rpeer_options"
+		done
+		echo "$server_conf"
+	else
+		echo "deny"
+		if [ -n "$client_server_conf" ]; then
+			echo "$client_server_conf"
+		else
+			for i in $(seq 1 $servers); do
+				echo "server $(get_node_name $[$servers * ($stratum - 2) + $i]) $client_server_options"
+			done
+		fi
+		for i in $(seq 1 $peers); do
+			[ $i -eq $peer -o $i -gt $clients ] && continue
+			echo -n "peer $(get_node_name $[$servers * ($stratum - 1) + $i]) $client_peer_options "
+			[ $i -lt $peer ] && echo "$client_lpeer_options" || echo "$client_rpeer_options"
+		done
+		echo "$client_conf"
+	fi
+}
+
+# Check if chrony was built with specified option in config.h
+check_config_h() {
+	local pattern=$1
+	grep -q "^#define $pattern" ../../config.h
+}
+
+# Check if the clock was well synchronized
+check_sync() {
+	local i sync_time max_time_error max_freq_error ret=0
+	local rms_time_error rms_freq_error
+
+	test_message 2 1 "checking clock sync time, max/rms time/freq error:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		[ $i -gt $[$servers * $server_strata] ] || continue
+
+		sync_time=$(find_sync tmp/log.offset tmp/log.freq $i \
+			$time_max_limit $freq_max_limit 1.0)
+		max_time_error=$(get_stat 'Maximum absolute offset' $i)
+		max_freq_error=$(get_stat 'Maximum absolute frequency' $i)
+		rms_time_error=$(get_stat 'RMS offset' $i)
+		rms_freq_error=$(get_stat 'RMS frequency' $i)
+
+		test_message 3 0 "node $i: $sync_time $(printf '%.2e %.2e %.2e %.2e' \
+			$max_time_error $max_freq_error $rms_time_error $rms_freq_error)"
+
+		check_stat $sync_time $min_sync_time $max_sync_time && \
+			check_stat $max_time_error 0.0 $time_max_limit && \
+			check_stat $max_freq_error 0.0 $freq_max_limit && \
+			check_stat $rms_time_error 0.0 $time_rms_limit && \
+			check_stat $rms_freq_error 0.0 $freq_rms_limit && \
+			test_ok || test_bad
+
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if chronyd exited properly
+check_chronyd_exit() {
+	local i ret=0
+
+	test_message 2 1 "checking chronyd exit:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		grep -q 'chronyd exiting' tmp/log.$i && \
+			! grep -q 'Adjustment.*exceeds.*exiting' tmp/log.$i && \
+			! grep -q 'Assertion.*failed' tmp/log.$i && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check for problems in source selection
+check_source_selection() {
+	local i ret=0
+
+	test_message 2 1 "checking source selection:"
+
+	for i in $(seq $[$servers * $server_strata + 1] $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		! grep -q 'no majority\|no selectable sources' tmp/log.$i && \
+			grep -q 'Selected source' tmp/log.$i && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if incoming and outgoing packet intervals are sane
+check_packet_interval() {
+	local i ret=0 mean_in_interval mean_out_interval min_in_interval min_out_interval
+
+	test_message 2 1 "checking mean/min incoming/outgoing packet interval:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		mean_in_interval=$(get_stat 'Mean incoming packet interval' $i)
+		mean_out_interval=$(get_stat 'Mean outgoing packet interval' $i)
+		min_in_interval=$(get_stat 'Minimum incoming packet interval' $i)
+		min_out_interval=$(get_stat 'Minimum outgoing packet interval' $i)
+
+		test_message 3 0 "node $i: $(printf '%.2e %.2e %.2e %.2e' \
+			$mean_in_interval $mean_out_interval $min_in_interval $min_out_interval)"
+
+		# Check that the mean intervals are non-zero and shorter than
+		# limit, incoming is not longer than outgoing for stratum 1
+		# servers, outgoing is not longer than incoming for clients,
+		# and the minimum outgoing interval is not shorter than the NTP
+		# sampling separation or iburst interval for clients
+		nodes=$[$servers * $server_strata + $clients]
+		check_stat $mean_in_interval 0.1 inf && \
+			check_stat $mean_out_interval 0.1 inf && \
+			([ $i -gt $servers ] || \
+				check_stat $mean_in_interval 0.0 $mean_out_interval 10*$jitter) && \
+			([ $i -le $[$servers * $server_strata] ] || \
+				check_stat $mean_out_interval $client_min_mean_out_interval \
+					$mean_in_interval 10*$jitter) && \
+			([ $i -le $[$servers * $server_strata] ] || \
+				check_stat $min_out_interval \
+					$([ $servers -gt 1 ] && echo 0.18 || echo 1.8) \
+					$client_max_min_out_interval) && \
+			test_ok || test_bad
+
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Compare chronyc output with specified pattern
+check_chronyc_output() {
+	local i ret=0 pattern=$1
+
+	test_message 2 1 "checking chronyc output:"
+
+	for i in $(seq $[$(get_chronyd_nodes) + 1] $[$(get_chronyd_nodes) + $clients]); do
+		test_message 3 0 "node $i:"
+
+		[[ "$(cat tmp/log.$i)" =~ $pattern ]] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check the number of messages matching a pattern in the client logs
+check_log_messages() {
+	local i count ret=0 pattern=$1 min=$2 max=$3
+
+	test_message 2 1 "checking number of messages \"$pattern\":"
+
+	for i in $(seq $[$servers * $server_strata + 1] $(get_chronyd_nodes)); do
+		count=$(grep "$pattern" tmp/log.$i | wc -l)
+		test_message 3 0 "node $i: $count"
+
+		[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check the number of messages matching a pattern in a specified file
+check_file_messages() {
+	local i count ret=0 pattern=$1 min=$2 max=$3
+	shift 3
+
+	test_message 2 1 "checking number of messages \"$pattern\":"
+
+	for i; do
+		count=$(grep "$pattern" tmp/$i | wc -l)
+		test_message 3 0 "$i: $count"
+
+		[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Check if only NTP port (123) was used
+check_packet_port() {
+	local i ret=0 port=123
+
+	test_message 2 1 "checking port numbers in packet log:"
+
+	for i in $(seq 1 $(get_chronyd_nodes)); do
+		test_message 3 0 "node $i:"
+
+		grep -E -q "^([0-9e.+-]+	){5}$port	" tmp/log.packets && \
+			! grep -E "^[0-9e.+-]+	$i	" tmp/log.packets | \
+			grep -E -q -v "^([0-9e.+-]+	){5}$port	" && \
+			test_ok || test_bad
+		[ $? -eq 0 ] || ret=1
+	done
+
+	return $ret
+}
+
+# Print test settings which differ from default value
+print_nondefaults() {
+	local defoptname optname
+
+	test_message 2 1 "non-default settings:"
+	for defoptname in ${!default_*}; do
+		optname=${defoptname#default_}
+		[ "${!defoptname}" = "${!optname}" ] || \
+			test_message 3 1 $optname=${!optname}
+	done
+}
+
+run_simulation() {
+	local nodes=$1
+
+	test_message 2 0 "running simulation:"
+
+	start_server $nodes \
+		-n 2 \
+		-o tmp/log.offset -f tmp/log.freq -p tmp/log.packets \
+		-R $(awk "BEGIN {print $update_interval < 0 ? 2^-($update_interval) : 1}") \
+		-r $(awk "BEGIN {print $max_sync_time * 2^$update_interval}") \
+		-l $(awk "BEGIN {print $limit * 2^$update_interval}") && test_ok || test_error
+}
+
+run_test() {
+	local i j n stratum node nodes step start freq offset conf options
+
+	test_message 1 1 "network with $servers*$server_strata servers and $clients clients:"
+	print_nondefaults
+
+	nodes=$(get_chronyd_nodes)
+	[ -n "$chronyc_conf" ] && nodes=$[$nodes + $clients]
+
+	export CLKNETSIM_UNIX_SUBNET=$[$cmdmon_unix != 0 ? 2 : 0]
+
+	for i in $(seq 1 $nodes); do
+		echo "node${i}_shift_pll = $shift_pll"
+		for j in $(seq 1 $nodes); do
+			echo "node${i}_delay${j} = $(get_delay_expr up)"
+			echo "node${j}_delay${i} = $(get_delay_expr down)"
+		done
+	done > tmp/conf
+
+	node=1
+
+	for stratum in $(seq 1 $[$server_strata + 1]); do
+		[ $stratum -le $server_strata ] && n=$servers || n=$clients
+
+		for i in $(seq 1 $n); do
+			test_message 2 0 "starting node $node:"
+
+			[ $pcap_dumps -ne 0 ] && export CLKNETSIM_PCAP_DUMP=tmp/pcap.$node
+
+			if [ $stratum -eq 1 ]; then
+				step=$server_step
+				start=$server_start
+				freq=""
+				[ $i -le $falsetickers ] &&
+					offset=$i.0 || offset=$primary_time_offset
+				options=$server_chronyd_options
+			elif [ $stratum -le $server_strata ]; then
+				step=$server_step
+				start=$server_start
+				freq=$(get_wander_expr)
+				offset=0.0
+				options=$server_chronyd_options
+			else
+				step=$client_step
+				start=$client_start
+				freq=$(get_wander_expr)
+				offset=$time_offset
+				options=$client_chronyd_options
+			fi
+
+			conf=$(get_chronyd_conf $stratum $i $n)
+
+			[ -z "$freq" ] || echo "node${node}_freq = $freq" >> tmp/conf
+			[ -z "$step" ] || echo "node${node}_step = $step" >> tmp/conf
+			[ -z "$refclock_jitter" ] || \
+				echo "node${node}_refclock = $(get_refclock_expr)" >> tmp/conf
+			echo "node${node}_offset = $offset" >> tmp/conf
+			echo "node${node}_start = $start" >> tmp/conf
+			start_client $node chronyd "$conf" "" "$options" && \
+				test_ok || test_error
+
+			[ $? -ne 0 ] && return 1
+			node=$[$node + 1]
+		done
+	done
+
+	for i in $(seq 1 $[$nodes - $node + 1]); do
+		test_message 2 0 "starting node $node:"
+
+		[ $pcap_dumps -ne 0 ] && export CLKNETSIM_PCAP_DUMP=tmp/pcap.$node
+
+		options=$([ $dns -eq 0 ] && printf "%s" "-n")
+		if [ $cmdmon_unix -ne 0 ]; then
+			options+=" -h /clknetsim/unix/$[$node - $clients]:1"
+		else
+			options+=" -h $(get_node_name $[$node - $clients])"
+		fi
+
+		echo "node${node}_start = $chronyc_start" >> tmp/conf
+		start_client $node chronyc "$chronyc_conf" "" "$options $chronyc_options" && \
+			test_ok || test_error
+
+		[ $? -ne 0 ] && return 1
+		node=$[$node + 1]
+	done
+
+	run_simulation $nodes
+}
diff --git a/test/system/001-minimal b/test/system/001-minimal
new file mode 100755
index 0000000..107fa3f
--- /dev/null
+++ b/test/system/001-minimal
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "minimal configuration"
+
+minimal_config=1
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+
+test_pass
diff --git a/test/system/002-extended b/test/system/002-extended
new file mode 100755
index 0000000..7a6734f
--- /dev/null
+++ b/test/system/002-extended
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "extended configuration"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/003-memlock b/test/system/003-memlock
new file mode 100755
index 0000000..e4ab1bf
--- /dev/null
+++ b/test/system/003-memlock
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "memory locking"
+
+extra_chronyd_options="-m"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/004-priority b/test/system/004-priority
new file mode 100755
index 0000000..bf8a04b
--- /dev/null
+++ b/test/system/004-priority
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "process priority"
+
+extra_chronyd_options="-P 1"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/006-privdrop b/test/system/006-privdrop
new file mode 100755
index 0000000..6d7b0c9
--- /dev/null
+++ b/test/system/006-privdrop
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features PRIVDROP || test_skip "PRIVDROP support disabled"
+
+user="nobody"
+
+test_start "dropping of root privileges"
+
+minimal_config=1
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+
+test_pass
diff --git a/test/system/007-cmdmon b/test/system/007-cmdmon
new file mode 100755
index 0000000..f9541d3
--- /dev/null
+++ b/test/system/007-cmdmon
@@ -0,0 +1,188 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "chronyc commands"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+has_ipv6=$(check_chronyd_features IPV6 && ping6 -c 1 ::1 > /dev/null 2>&1 && echo 1 || echo 0)
+
+for command in \
+	"allow 1.2.3.4" \
+	"deny 1.2.3.4" \
+	"cmddeny" \
+	"cmdallow" \
+	"cmddeny 1.2.3.4" \
+	"cmdallow 1.2.3.4" \
+	"add server 127.123.1.1" \
+	"delete 127.123.1.1" \
+	"burst 1/1" \
+	"cyclelogs" \
+	"dfreq 1.0e-3" \
+	"doffset -0.1" \
+	"dump" \
+	"offline" \
+	"local off" \
+	"local" \
+	"online" \
+	"onoffline" \
+	"maxdelay $server 1e-1" \
+	"maxdelaydevratio $server 5.0" \
+	"maxdelayratio $server 3.0" \
+	"maxpoll $server 12" \
+	"maxupdateskew $server 10.0" \
+	"minpoll $server 10" \
+	"minstratum $server 1" \
+	"polltarget $server 10" \
+	"refresh" \
+	"rekey" \
+	"reload sources" \
+	"reselect" \
+	"reselectdist 1e-3" \
+	"reset sources" \
+	"selectopts $server -noselect +trust +prefer +require" \
+	"smoothtime reset" \
+	"smoothtime activate" \
+; do
+	run_chronyc "$command" || test_fail
+	check_chronyc_output "^200 OK$" || test_fail
+done
+
+run_chronyc "accheck $server" || test_fail
+check_chronyc_output "^208 Access allowed$" || test_fail
+run_chronyc "accheck 1.2.3.4" || test_fail
+check_chronyc_output "^209 Access denied$" || test_fail
+
+run_chronyc "cmdaccheck 1.2.3.4" || test_fail
+check_chronyc_output "^208 Access allowed$" || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                      -     0    0    0    -    0    0    0    0$" \
+	|| test_chronyc
+
+run_chronyc "clients" || test_fail
+check_chronyc_output "^Hostname                      NTP   Drop Int IntL Last     Cmd   Drop Int  Last
+===============================================================================
+127\.0\.0\.1               [0-9 ]+    0 [-0-9 ]+   -  [ 0-9]+       0      0   -     -$" \
+	|| test_fail
+
+run_chronyc "ntpdata $server" || test_fail
+check_chronyc_output "^Remote address  : 127\.0\.0\.1 \(7F000001\)
+Remote port     : [0-9]+
+Local address   : 127\.0\.0\.1 \(7F000001\)
+Leap status     : Normal
+Version         : 4
+Mode            : Server
+Stratum         : 10
+Poll interval   : (-6|[0-9]+) \([0-9]+ seconds\)
+Precision       : [0-9 +-]+ \(0\.[0-9]+ seconds\)
+Root delay      : 0\.000000 seconds
+Root dispersion : 0\.000000 seconds
+Reference ID    : 7F7F0101 \(\)
+Reference time  : [A-Za-z0-9: ]+
+Offset          : [+-]0\.......... seconds
+Peer delay      : 0\.......... seconds
+Peer dispersion : 0\.......... seconds
+Response time   : 0\.......... seconds
+Jitter asymmetry: \+0\.00
+NTP tests       : 111 111 1110
+Interleaved     : No
+Authenticated   : No
+TX timestamping : (Daemon|Kernel)
+RX timestamping : (Daemon|Kernel)
+Total TX        : [0-9]+
+Total RX        : [0-9]+
+Total valid RX  : [0-9]+
+Total good RX   : [0-9]+$" || test_fail
+
+run_chronyc "selectdata" || test_fail
+check_chronyc_output "^S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+s 127\.0\.0\.1                 N -PTR- -PTR-    0   1\.0    \+0ns    \+0ns  \?$" || test_fail
+
+run_chronyc "serverstats" || test_fail
+check_chronyc_output "^NTP packets received       : [0-9]+
+NTP packets dropped        : 0
+Command packets received   : [0-9]+
+Command packets dropped    : 0
+Client log records dropped : 0
+NTS-KE connections accepted: 0
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 0
+Interleaved NTP packets    : 0
+NTP timestamps held        : 0
+NTP timestamp span         : 0
+NTP daemon RX timestamps   : 0
+NTP daemon TX timestamps   : [0-9]+
+NTP kernel RX timestamps   : [0-9]+
+NTP kernel TX timestamps   : 0
+NTP hardware RX timestamps : 0
+NTP hardware TX timestamps : 0$"|| test_fail
+
+run_chronyc "manual on" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "settime now" || test_fail
+check_chronyc_output "^200 OK
+Clock was.*$" || test_fail
+
+run_chronyc "manual delete 0" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "settime now" || test_fail
+check_chronyc_output "^200 OK
+Clock was.*$" || test_fail
+
+run_chronyc "manual list" || test_fail
+check_chronyc_output "^210 n_samples = 1
+#    Date     Time\(UTC\)    Slewed   Original   Residual
+=======================================================
+ 0.*$" || test_fail
+
+run_chronyc "manual reset" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "manual off" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+run_chronyc "shutdown" || test_fail
+check_chronyc_output "^200 OK$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+start_chronyd || test_fail
+
+run_chronyc "makestep" && test_fail
+check_chronyc_output "500 Failure" || test_fail
+
+run_chronyc "trimrtc" && test_fail
+check_chronyc_output "513 RTC driver not running" || test_fail
+
+run_chronyc "writertc" && test_fail
+check_chronyc_output "513 RTC driver not running" || test_fail
+
+chronyc_host=127.0.0.1
+
+run_chronyc "tracking" || test_fail
+check_chronyc_output "^Reference ID" || test_fail
+
+run_chronyc "makestep" && test_fail
+check_chronyc_output "^501 Not authorised$" || test_fail
+
+if [ "$has_ipv6" = "1" ]; then
+	chronyc_host=::1
+
+	run_chronyc "tracking" || test_fail
+	check_chronyc_output "^Reference ID" || test_fail
+
+	run_chronyc "makestep" && test_fail
+	check_chronyc_output "^501 Not authorised$" || test_fail
+fi
+
+stop_chronyd || test_fail
+
+test_pass
diff --git a/test/system/008-confload b/test/system/008-confload
new file mode 100755
index 0000000..a7fc1d5
--- /dev/null
+++ b/test/system/008-confload
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "loading of configuration"
+
+minimal_config=1
+extra_chronyd_directives="
+include $TEST_DIR/conf1.d/conf.1
+confdir $TEST_DIR/conf1.d
+confdir $TEST_DIR/conf2.d $TEST_DIR/conf3.d $TEST_DIR/conf4.d
+sourcedir $TEST_DIR/conf5.d
+include $TEST_DIR/conf1.d/conf.2"
+
+mkdir $TEST_DIR/conf{1,2,3,4,5}.d
+
+echo "server 127.123.1.1" > $TEST_DIR/conf1.d/conf.1
+echo "server 127.123.1.2" > $TEST_DIR/conf1.d/conf.2
+echo "server 127.123.1.3" > $TEST_DIR/conf1.d/3.conf
+echo "server 127.123.1.4" > $TEST_DIR/conf1.d/4.conf
+echo "server 127.123.2.2" > $TEST_DIR/conf2.d/2.conf
+echo "server 127.123.2.3" > $TEST_DIR/conf2.d/3.conf
+echo "server 127.123.3.1" > $TEST_DIR/conf3.d/1.conf
+echo "server 127.123.3.2" > $TEST_DIR/conf3.d/2.conf
+echo "server 127.123.3.3" > $TEST_DIR/conf3.d/3.conf
+echo "server 127.123.4.1" > $TEST_DIR/conf4.d/1.conf
+echo "server 127.123.4.2" > $TEST_DIR/conf4.d/2.conf
+echo "server 127.123.4.3" > $TEST_DIR/conf4.d/3.conf
+echo "server 127.123.4.4" > $TEST_DIR/conf4.d/4.conf
+echo "server 127.123.5.1" > $TEST_DIR/conf5.d/1.sources
+echo "server 127.123.5.2" > $TEST_DIR/conf5.d/2.sources
+echo "server 127.123.5.3" > $TEST_DIR/conf5.d/3.sources
+
+start_chronyd || test_fail
+
+run_chronyc "sources" || test_fail
+check_chronyc_output "^[^=]*
+=*
+.. 127\.123\.1\.1 [^^]*
+.. 127\.123\.1\.3 [^^]*
+.. 127\.123\.1\.4 [^^]*
+.. 127\.123\.3\.1 [^^]*
+.. 127\.123\.2\.2 [^^]*
+.. 127\.123\.2\.3 [^^]*
+.. 127\.123\.4\.4 [^^]*
+.. 127\.123\.1\.2 [^^]*
+.. 127\.123\.5\.1 [^^]*
+.. 127\.123\.5\.2 [^^]*
+.. 127\.123\.5\.3 [^^]*$" || test_fail
+
+rm $TEST_DIR/conf5.d/1.sources
+echo "server 127.123.5.2 minpoll 7" > $TEST_DIR/conf5.d/2.sources
+echo > $TEST_DIR/conf5.d/3.sources
+echo "server 127.123.5.4" > $TEST_DIR/conf5.d/4.sources
+
+run_chronyc "reload sources" || test_fail
+
+run_chronyc "sources" || test_fail
+check_chronyc_output "^[^=]*
+=*
+.. 127\.123\.1\.1 [^^]*
+.. 127\.123\.1\.3 [^^]*
+.. 127\.123\.1\.4 [^^]*
+.. 127\.123\.3\.1 [^^]*
+.. 127\.123\.2\.2 [^^]*
+.. 127\.123\.2\.3 [^^]*
+.. 127\.123\.4\.4 [^^]*
+.. 127\.123\.1\.2 *[05]   6 [^^]*
+.. 127\.123\.5\.2 *[05]   7 [^^]*
+.. 127\.123\.5\.4 [^^]*$" || test_fail
+
+stop_chronyd || test_fail
+
+test_pass
diff --git a/test/system/009-binddevice b/test/system/009-binddevice
new file mode 100755
index 0000000..fc64ae2
--- /dev/null
+++ b/test/system/009-binddevice
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+[ "$(uname -s)" = "Linux" ] || test_skip "non-Linux system"
+
+test_start "binddevice directives"
+
+extra_chronyd_directives="
+binddevice lo
+bindacqdevice lo
+bindcmddevice lo"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "ntpdata $server" || test_fail
+check_chronyc_output "^Remote address" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/010-nts b/test/system/010-nts
new file mode 100755
index 0000000..8d92bbc
--- /dev/null
+++ b/test/system/010-nts
@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features NTS || test_skip "NTS support disabled"
+certtool --help &> /dev/null || test_skip "certtool missing"
+
+test_start "NTS authentication"
+
+cat > $TEST_DIR/cert.cfg <<EOF
+cn = "chrony-nts-test"
+dns_name = "chrony-nts-test"
+ip_address = "$server"
+serial = 001
+activation_date = "$[$(date '+%Y') - 1]-01-01 00:00:00 UTC"
+expiration_date = "$[$(date '+%Y') + 2]-01-01 00:00:00 UTC"
+signing_key
+encryption_key
+EOF
+
+certtool --generate-privkey --key-type=ed25519 --outfile $TEST_DIR/server.key \
+	&> $TEST_DIR/certtool.log
+certtool --generate-self-signed --load-privkey $TEST_DIR/server.key \
+	--template $TEST_DIR/cert.cfg --outfile $TEST_DIR/server.crt &>> $TEST_DIR/certtool.log
+chown $user $TEST_DIR/server.*
+
+ntpport=$(get_free_port)
+ntsport=$(get_free_port)
+
+server_options="port $ntpport nts ntsport $ntsport"
+extra_chronyd_directives="
+port $ntpport
+ntsport $ntsport
+ntsserverkey $TEST_DIR/server.key
+ntsservercert $TEST_DIR/server.crt
+ntstrustedcerts $TEST_DIR/server.crt
+ntsdumpdir $TEST_LIBDIR
+ntsprocesses 3"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                    NTS     1   (30|15)  (128|256)    [0-9]    0    0    [78]  ( 64|100)$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+server_options="port $ntpport nts ntsport $((ntsport + 1))"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+
+run_chronyc "authdata" || test_fail
+check_chronyc_output "^Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+127\.0\.0\.1                    NTS     1   (30|15)  (128|256)    [0-9]    0    0    [78]  ( 64|100)$" || test_fail
+
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/099-scfilter b/test/system/099-scfilter
new file mode 100755
index 0000000..7be02bd
--- /dev/null
+++ b/test/system/099-scfilter
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features SCFILTER || test_skip "SCFILTER support disabled"
+
+test_start "system call filter in non-destructive tests"
+
+for level in 1 2 -1 -2; do
+	test_message 1 1 "level $level:"
+	for test in 0[0-8][0-9]-*[^_]; do
+		test_message 2 0 "$test"
+		TEST_SCFILTER=$level "./$test" > /dev/null 2> /dev/null
+		result=$?
+
+		if [ $result != 0 ] && [ $result != 9 ] ; then
+			test_bad
+			test_fail
+		fi
+		test_ok
+	done
+done
+
+test_pass
diff --git a/test/system/100-clockupdate b/test/system/100-clockupdate
new file mode 100755
index 0000000..191e461
--- /dev/null
+++ b/test/system/100-clockupdate
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+test_start "update of system clock"
+
+clock_control=1
+minimal_config=1
+
+start_chronyd || test_fail
+run_chronyc "dfreq 1e-3" || test_fail
+check_chronyc_output "200 OK" || test_fail
+
+before=$(date '+%s')
+run_chronyc "doffset -1.0" || test_fail
+check_chronyc_output "200 OK" || test_fail
+run_chronyc "makestep" || test_fail
+check_chronyc_output "200 OK" || test_fail
+after=$(date '+%s')
+
+test_message 1 0 "checking system clock"
+[ "$before" -lt "$after" ] && test_ok || test_bad || test_fail
+
+run_chronyc "doffset 1.0" || test_fail
+run_chronyc "makestep" || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_message_count "System clock was stepped by" 2 2 || test_fail
+
+test_pass
diff --git a/test/system/101-rtc b/test/system/101-rtc
new file mode 100755
index 0000000..68bce68
--- /dev/null
+++ b/test/system/101-rtc
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features RTC || test_skip "RTC support disabled"
+[ -c "/dev/rtc" ] || test_skip "missing /dev/rtc"
+
+test_start "real-time clock"
+
+minimal_config=1
+extra_chronyd_options="-s"
+extra_chronyd_directives="rtcfile $TEST_DIR/rtcfile"
+echo "1 $(date +%s) 0.0 0.0" > "$TEST_DIR/rtcfile"
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_message_count "\(clock off from RTC\|RTC time before last\|Could not \(enable\|disable\) RTC interrupt\)" 1 1 || test_fail
+
+test_pass
diff --git a/test/system/102-hwtimestamp b/test/system/102-hwtimestamp
new file mode 100755
index 0000000..6b86d20
--- /dev/null
+++ b/test/system/102-hwtimestamp
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+[ "$(uname -s)" = "Linux" ] || test_skip "non-Linux system"
+
+hwts_iface=""
+for iface_path in /sys/class/net/*; do
+	iface=$(basename "$iface_path")
+	if ethtool -T "$iface" 2> /dev/null | grep -q '	all\($\| \)'; then
+		hwts_iface="$iface"
+		break
+	fi
+done
+
+[ -n "$hwts_iface" ] || test_skip "no HW timestamping interface found"
+
+test_start "hardware timestamping"
+
+minimal_config=1
+extra_chronyd_directives="hwtimestamp $hwts_iface"
+
+start_chronyd || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_message_count "Enabled HW timestamping on $hwts_iface" 1 1 || test_fail
+
+test_pass
diff --git a/test/system/103-refclock b/test/system/103-refclock
new file mode 100755
index 0000000..e5b74e0
--- /dev/null
+++ b/test/system/103-refclock
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features REFCLOCK || test_skip "refclock support disabled"
+
+test_start "reference clocks"
+
+extra_chronyd_directives="
+refclock SOCK $TEST_DIR/refclock.sock
+refclock SHM 100"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/104-systemdirs b/test/system/104-systemdirs
new file mode 100755
index 0000000..15508dc
--- /dev/null
+++ b/test/system/104-systemdirs
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+TEST_LIBDIR=${CHRONY_LIBDIR:-/var/lib/chrony}
+TEST_LOGDIR=${CHRONY_LOGDIR:-/var/log/chrony}
+TEST_RUNDIR=${CHRONY_RUNDIR:-/var/run/chrony}
+
+. ./test.common
+
+user=$(ls -ld "$TEST_RUNDIR" 2> /dev/null | awk '{print $3}')
+
+test_start "system directories"
+
+start_chronyd || test_fail
+wait_for_sync || test_fail
+stop_chronyd || test_fail
+check_chronyd_messages || test_fail
+check_chronyd_files || test_fail
+
+test_pass
diff --git a/test/system/199-scfilter b/test/system/199-scfilter
new file mode 100755
index 0000000..40441b7
--- /dev/null
+++ b/test/system/199-scfilter
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+. ./test.common
+
+check_chronyd_features SCFILTER || test_skip "SCFILTER support disabled"
+
+test_start "system call filter in destructive tests"
+
+for level in 1 2 -1 -2; do
+	test_message 1 1 "level $level:"
+	for test in 1[0-8][0-9]-*[^_]; do
+		test_message 2 0 "$test"
+		TEST_SCFILTER=$level "./$test" > /dev/null 2> /dev/null
+		result=$?
+
+		if [ $result != 0 ] && [ $result != 9 ] ; then
+			test_bad
+			test_fail
+		fi
+		test_ok
+	done
+done
+
+test_pass
diff --git a/test/system/run b/test/system/run
new file mode 100755
index 0000000..5516ed4
--- /dev/null
+++ b/test/system/run
@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+
+print_help() {
+	echo "$1 [-a] [-d] [TEST]..."
+}
+
+run_test() {
+	local result name=$1
+
+	if [ $destructive -ne 1 ] && [[ "$name" == 1[0-9][0-9]-* ]]; then
+		echo "SKIP (destructive test)"
+		return 9
+	fi
+
+	./$name
+	result=$?
+
+	if [ $result -ne 0 -a $result -ne 9 ]; then
+		if [ $abort_on_fail -ne 0 ]; then
+			exit 1
+		fi
+	fi
+
+	return $result
+}
+
+passed=() failed=() skipped=()
+
+abort_on_fail=0
+destructive=0
+
+while getopts ":ad" opt; do
+	case $opt in
+		a) abort_on_fail=1;;
+		d) destructive=1;;
+		*) print_help "$0"; exit 3;;
+	esac
+done
+
+shift $[$OPTIND - 1]
+
+[ $# -gt 0 ] && tests=($@) || tests=([0-9]*-*[^_])
+
+for test in "${tests[@]}"; do
+	printf "%s   " "$test"
+	run_test $test
+	result=$?
+	echo
+
+	case $result in
+		0) passed=(${passed[@]} $test);;
+		9) skipped=(${skipped[@]} $test);;
+		*) failed=(${failed[@]} $test);;
+	esac
+done
+
+echo
+echo "SUMMARY:"
+echo "  TOTAL  $[${#passed[@]} + ${#failed[@]} + ${#skipped[@]}]"
+echo "  PASSED ${#passed[@]}"
+echo "  FAILED ${#failed[@]}    (${failed[@]})"
+echo "  SKIPPED ${#skipped[@]}   (${skipped[@]})"
+
+[ ${#failed[@]} -eq 0 ]
diff --git a/test/system/test.common b/test/system/test.common
new file mode 100644
index 0000000..aa48ac6
--- /dev/null
+++ b/test/system/test.common
@@ -0,0 +1,375 @@
+# Copyright (C) Miroslav Lichvar  2009
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of version 2 of the GNU General Public License as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+export LC_ALL=C
+export PATH=${CHRONY_PATH:-../..}:$PATH
+
+TEST_DIR=${TEST_DIR:-$(pwd)/tmp}
+TEST_LIBDIR=${TEST_LIBDIR:-$TEST_DIR}
+TEST_LOGDIR=${TEST_LOGDIR:-$TEST_DIR}
+TEST_RUNDIR=${TEST_RUNDIR:-$TEST_DIR}
+TEST_SCFILTER=${TEST_SCFILTER:-0}
+
+test_start() {
+	check_chronyd_features NTP CMDMON || test_skip "NTP/CMDMON support disabled"
+
+	[ "${#TEST_DIR}" -ge 5 ] || test_skip "invalid TEST_DIR"
+
+	rm -rf "$TEST_DIR"
+	mkdir -p "$TEST_DIR" && chmod 700 "$TEST_DIR" || test_skip "could not create $TEST_DIR"
+
+	[ -d "$TEST_LIBDIR" ] || test_skip "missing $TEST_LIBDIR"
+	[ -d "$TEST_LOGDIR" ] || test_skip "missing $TEST_LOGDIR"
+	[ -d "$TEST_RUNDIR" ] || test_skip "missing $TEST_RUNDIR"
+
+	rm -f "$TEST_LIBDIR"/* "$TEST_LOGDIR"/* "$TEST_RUNDIR"/*
+
+	if [ "$user" != "root" ]; then
+		id -u "$user" > /dev/null 2> /dev/null || test_skip "missing user $user"
+		chown "$user:$(id -g "$user")" "$TEST_DIR" || test_skip "could not chown $TEST_DIR"
+		su "$user" -s /bin/sh -c "touch $TEST_DIR/test" 2> /dev/null || \
+			test_skip "$user cannot access $TEST_DIR"
+		rm "$TEST_DIR/test"
+	else
+		chown 0:0 "$TEST_DIR" || test_skip "could not chown $TEST_DIR"
+	fi
+
+	echo "Testing $*:"
+}
+
+test_pass() {
+	echo "PASS"
+	exit 0
+}
+
+test_fail() {
+	echo "FAIL"
+	exit 1
+}
+
+test_skip() {
+	local msg=$1
+
+	[ -n "$msg" ] && echo "SKIP ($msg)" || echo "SKIP"
+	exit 9
+}
+
+test_ok() {
+	pad_line
+	echo -e "\tOK"
+	return 0
+}
+
+test_bad() {
+	pad_line
+	echo -e "\tBAD"
+	return 1
+}
+
+test_error() {
+	pad_line
+	echo -e "\tERROR"
+	return 1
+}
+
+chronyd=$(command -v chronyd)
+chronyc=$(command -v chronyc)
+
+[ $EUID -eq 0 ] || test_skip "not root"
+
+[ -x "$chronyd" ] || test_skip "chronyd not found"
+[ -x "$chronyc" ] || test_skip "chronyc not found"
+
+if netstat -aln > /dev/null 2> /dev/null; then
+	port_list_command="netstat -aln"
+elif ss -atun > /dev/null 2> /dev/null; then
+	port_list_command="ss -atun"
+else
+	test_skip "missing netstat or ss"
+fi
+
+# Default test testings
+default_minimal_config=0
+default_extra_chronyd_directives=""
+default_extra_chronyd_options=""
+default_clock_control=0
+default_server=127.0.0.1
+default_server_name=127.0.0.1
+default_server_options=""
+default_user=root
+
+# Initialize test settings from their defaults
+for defoptname in ${!default_*}; do
+	optname=${defoptname#default_}
+	[ -z "${!optname}" ] && declare "$optname"="${!defoptname}"
+done
+
+msg_length=0
+pad_line() {
+	local line_length=56
+	[ $msg_length -lt $line_length ] && \
+		printf "%$((line_length - msg_length))s" ""
+	msg_length=0
+}
+
+# Print aligned message
+test_message() {
+	local level=$1 eol=$2
+	shift 2
+	local msg="$*"
+
+	while [ "$level" -gt 0 ]; do
+		echo -n "  "
+		level=$((level - 1))
+		msg_length=$((msg_length + 2))
+	done
+	echo -n "$msg"
+
+	msg_length=$((msg_length + ${#msg}))
+	if [ "$eol" -ne 0 ]; then
+		echo
+		msg_length=0
+	fi
+}
+
+# Check if chronyd has specified features
+check_chronyd_features() {
+	local feature features
+
+	features=$($chronyd -v | sed 's/.*(\(.*\)).*/\1/')
+
+	for feature; do
+		echo "$features" | grep -q "+$feature" || return 1
+	done
+}
+
+# Print test settings which differ from default value
+print_nondefaults() {
+	local defoptname optname
+
+	test_message 1 1 "non-default settings:"
+	for defoptname in ${!default_*}; do
+		optname=${defoptname#default_}
+		[ "${!defoptname}" = "${!optname}" ] || \
+			test_message 2 1 "$optname"=${!optname}
+	done
+}
+
+get_conffile() {
+	echo "$TEST_DIR/chronyd.conf"
+}
+
+get_pidfile() {
+	echo "$TEST_RUNDIR/chronyd.pid"
+}
+
+get_logfile() {
+	echo "$TEST_LOGDIR/chronyd.log"
+}
+
+get_cmdsocket() {
+	echo "$TEST_RUNDIR/chronyd.sock"
+}
+
+# Find a free port in the 10000-20000 range (their use is racy)
+get_free_port() {
+	local port
+
+	while true; do
+		port=$((RANDOM % 10000 + 10000))
+		$port_list_command | grep -q '^\(tcp\|udp\).*[:.]'"$port " && continue
+		break
+	done
+
+	echo $port
+}
+
+generate_chrony_conf() {
+	local ntpport cmdport
+
+	ntpport=$(get_free_port)
+	cmdport=$(get_free_port)
+
+	echo "0.0 10000" > "$TEST_LIBDIR/driftfile"
+	echo "1 MD5 abcdefghijklmnopq" > "$TEST_DIR/keys"
+	chown "$user:$(id -g "$user")" "$TEST_LIBDIR/driftfile" "$TEST_DIR/keys"
+	echo "0.0" > "$TEST_DIR/tempcomp"
+
+	(
+		echo "pidfile $(get_pidfile)"
+		echo "bindcmdaddress $(get_cmdsocket)"
+		echo "port $ntpport"
+		echo "cmdport $cmdport"
+
+		echo "$extra_chronyd_directives"
+
+		[ "$minimal_config" -ne 0 ] && exit 0
+
+		echo "allow"
+		echo "cmdallow"
+		echo "local"
+
+		echo "server $server_name port $ntpport minpoll -6 maxpoll -6 $server_options"
+
+		[ "$server" = "127.0.0.1" ] && echo "bindacqaddress $server"
+		echo "bindaddress 127.0.0.1"
+		echo "bindcmdaddress 127.0.0.1"
+		echo "dumpdir $TEST_RUNDIR"
+		echo "logdir $TEST_LOGDIR"
+		echo "log tempcomp rawmeasurements refclocks statistics tracking rtc"
+		echo "logbanner 0"
+		echo "smoothtime 100.0 0.001"
+		echo "leapsectz right/UTC"
+		echo "dscp 46"
+
+		echo "include /dev/null"
+		echo "keyfile $TEST_DIR/keys"
+		echo "driftfile $TEST_LIBDIR/driftfile"
+		echo "tempcomp $TEST_DIR/tempcomp 0.1 0 0 0 0"
+
+	) > "$(get_conffile)"
+}
+
+get_chronyd_options() {
+	[ "$clock_control" -eq 0 ] && echo "-x"
+	echo "-l $(get_logfile)"
+	echo "-f $(get_conffile)"
+	echo "-u $user"
+	echo "-F $TEST_SCFILTER"
+	echo "$extra_chronyd_options"
+}
+
+# Start a chronyd instance
+start_chronyd() {
+	local pid pidfile=$(get_pidfile)
+
+	print_nondefaults
+	test_message 1 0 "starting chronyd"
+
+	generate_chrony_conf
+
+	trap stop_chronyd EXIT
+
+	rm -f "$TEST_LOGDIR"/*.log
+
+	$CHRONYD_WRAPPER "$chronyd" $(get_chronyd_options) > "$TEST_DIR/chronyd.out" 2>&1
+
+	[ $? -eq 0 ] && [ -f "$pidfile" ] && ps -p "$(cat "$pidfile")" > /dev/null && test_ok || test_error
+}
+
+wait_for_sync() {
+	local prev_length
+
+	test_message 1 0 "waiting for synchronization"
+	prev_length=$msg_length
+
+	for i in $(seq 1 10); do
+		run_chronyc "ntpdata $server" > /dev/null 2>&1 || break
+		if check_chronyc_output "Total RX +: [1-9]" > /dev/null 2>&1; then
+			msg_length=$prev_length
+			test_ok
+			return
+		fi
+		sleep 1
+	done
+
+	msg_length=$prev_length
+	test_error
+}
+
+# Stop the chronyd instance
+stop_chronyd() {
+	local pid pidfile
+
+	pidfile=$(get_pidfile)
+	[ -f "$pidfile" ] || return 0
+
+	pid=$(cat "$pidfile")
+
+	test_message 1 0 "stopping chronyd"
+
+	if ! kill "$pid" 2> /dev/null; then
+		test_error
+		return
+	fi
+
+	# Wait for the process to terminate (we cannot use "wait")
+	while ps -p "$pid" > /dev/null; do
+		sleep 0.1
+	done
+
+	test_ok
+}
+
+# Check chronyd log for expected and unexpected messages
+check_chronyd_messages() {
+	local logfile=$(get_logfile)
+
+	test_message 1 0 "checking chronyd messages"
+
+	grep -q 'chronyd exiting' "$logfile" && \
+		([ "$clock_control" -eq 0 ] || ! grep -q 'Disabled control of system clock' "$logfile") && \
+		([ "$clock_control" -ne 0 ] || grep -q 'Disabled control of system clock' "$logfile") && \
+		([ "$minimal_config" -ne 0 ] || grep -q 'Frequency .* read from' "$logfile") && \
+		grep -q 'chronyd exiting' "$logfile" && \
+		! grep -q 'Could not' "$logfile" && \
+		! grep -q 'Disabled command socket' "$logfile" && \
+		test_ok || test_bad
+}
+
+# Check the number of messages matching a pattern in a specified file
+check_chronyd_message_count() {
+	local count pattern=$1 min=$2 max=$3 logfile=$(get_logfile)
+
+	test_message 1 0 "checking message \"$pattern\""
+
+	count=$(grep "$pattern" "$(get_logfile)" | wc -l)
+
+	[ "$min" -le "$count" ] && [ "$count" -le "$max" ] && test_ok || test_bad
+}
+
+# Check the logs and dump file for measurements and a clock update
+check_chronyd_files() {
+	test_message 1 0 "checking chronyd files"
+
+	grep -q " $server .* 111 111 1110 " "$TEST_LOGDIR/measurements.log" && \
+		[ -f "$TEST_LOGDIR/tempcomp.log" ] && [ "$(wc -l < "$TEST_LOGDIR/tempcomp.log")" -ge 2 ] && \
+		test_ok || test_bad
+}
+
+# Run a chronyc command
+run_chronyc() {
+	local host=$chronyc_host options="-n -m"
+
+	test_message 1 0 "running chronyc $([ -n "$host" ] && echo "@$host ")$*"
+
+	if [ -z "$host" ]; then
+		host="$(get_cmdsocket)"
+	else
+		options="$options -p $(grep cmdport "$(get_conffile)" | awk '{print $2}')"
+	fi
+
+	$CHRONYC_WRAPPER "$chronyc" -h "$host" $options "$@" > "$TEST_DIR/chronyc.out" && \
+		test_ok || test_error
+}
+
+# Compare chronyc output with specified pattern
+check_chronyc_output() {
+	local pattern=$1
+
+	test_message 1 0 "checking chronyc output"
+
+	[[ "$(cat "$TEST_DIR/chronyc.out")" =~ $pattern ]] && test_ok || test_bad
+}
diff --git a/test/unit/Makefile.in b/test/unit/Makefile.in
new file mode 100644
index 0000000..9979840
--- /dev/null
+++ b/test/unit/Makefile.in
@@ -0,0 +1,48 @@
+TEST_WRAPPER =
+CHRONY_SRCDIR = ../..
+
+CC = @CC@
+CFLAGS = @CFLAGS@
+CPPFLAGS = -I$(CHRONY_SRCDIR) @CPPFLAGS@
+LDFLAGS = @LDFLAGS@ @LIBS@ @EXTRA_LIBS@
+
+SHARED_OBJS = test.o
+
+TEST_OBJS := $(sort $(patsubst %.c,%.o,$(wildcard *.c)))
+TESTS := $(patsubst %.o,%.test,$(filter-out $(SHARED_OBJS),$(TEST_OBJS)))
+
+CHRONYD_OBJS := $(patsubst %.o,$(CHRONY_SRCDIR)/%.o,$(filter-out main.o,\
+		  $(filter %.o,$(shell $(MAKE) -f $(CHRONY_SRCDIR)/Makefile \
+					print-chronyd-objects NODEPS=1))))
+
+all: $(TESTS)
+
+$(CHRONYD_OBJS): ;
+
+%.test: %.o $(SHARED_OBJS) $(CHRONYD_OBJS)
+	$(CC) $(CFLAGS) -o $@ $(filter-out $(CHRONY_SRCDIR)/$<,$^) $(LDFLAGS)
+
+%.o: %.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) -c $<
+
+check: $(TESTS)
+	@ret=0; \
+	for t in $^; do \
+	  $(TEST_WRAPPER) ./$$t || ret=1; \
+	done; \
+	exit $$ret
+
+clean:
+	rm -f *.o *.gcda *.gcno core.* $(TESTS)
+	rm -rf .deps
+
+distclean: clean
+	rm -f Makefile
+
+.deps:
+	@mkdir .deps
+
+.deps/%.d: %.c | .deps
+	@$(CC) -MM $(CPPFLAGS) -MT '$(<:%.c=%.o) $@' $< -o $@
+
+-include $(TEST_OBJS:%.o=.deps/%.d)
diff --git a/test/unit/addrfilt.c b/test/unit/addrfilt.c
new file mode 100644
index 0000000..b236073
--- /dev/null
+++ b/test/unit/addrfilt.c
@@ -0,0 +1,83 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <addrfilt.c>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+void
+test_unit(void)
+{
+  int i, j, sub, maxsub;
+  IPAddr ip;
+  ADF_AuthTable table;
+
+  table = ADF_CreateTable();
+
+  for (i = 0; i < 100; i++) {
+    for (j = 0; j < 1000; j++) {
+      if (j % 2) {
+        maxsub = 32;
+        TST_GetRandomAddress(&ip, IPADDR_INET4, -1);
+      } else {
+        maxsub = 128;
+        TST_GetRandomAddress(&ip, IPADDR_INET6, -1);
+      }
+
+      DEBUG_LOG("address %s", UTI_IPToString(&ip));
+
+      sub = random() % (maxsub + 1);
+
+      TEST_CHECK(!ADF_IsAllowed(table, &ip));
+      ADF_Allow(table, &ip, sub);
+      TEST_CHECK(ADF_IsAllowed(table, &ip));
+
+      if (sub < maxsub) {
+        TST_SwapAddressBit(&ip, sub);
+        TEST_CHECK(ADF_IsAllowed(table, &ip));
+      }
+
+      if (sub > 0) {
+        TST_SwapAddressBit(&ip, sub - 1);
+        TEST_CHECK(!ADF_IsAllowed(table, &ip));
+        if (sub % 4 != 1) {
+          ADF_Deny(table, &ip, sub - 1);
+          TST_SwapAddressBit(&ip, sub - 1);
+          TEST_CHECK(!ADF_IsAllowed(table, &ip));
+        }
+      }
+
+      if (sub > 4) {
+        ADF_AllowAll(table, &ip, sub - 4);
+        TEST_CHECK(ADF_IsAllowed(table, &ip));
+      }
+
+      ADF_DenyAll(table, &ip, 0);
+    }
+
+    ip.family = IPADDR_INET4;
+    ADF_DenyAll(table, &ip, 0);
+    ip.family = IPADDR_INET6;
+    ADF_DenyAll(table, &ip, 0);
+  }
+
+  ADF_DestroyTable(table);
+}
diff --git a/test/unit/array.c b/test/unit/array.c
new file mode 100644
index 0000000..65ad1d8
--- /dev/null
+++ b/test/unit/array.c
@@ -0,0 +1,97 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <array.c>
+#include <util.h>
+#include "test.h"
+
+void
+test_unit(void)
+{
+  unsigned int i, j, k, k2, l, es, s;
+  unsigned char *el1, el2[20];
+  ARR_Instance a;
+
+  for (i = 0; i < 1000; i++) {
+    es = random() % sizeof (el2) + 1;
+
+    a = ARR_CreateInstance(es);
+
+    TEST_CHECK(ARR_GetSize(a) == 0);
+
+    for (j = 0; j < 100; j++) {
+      s = ARR_GetSize(a);
+
+      switch (random() % 6) {
+        case 0:
+          el1 = ARR_GetNewElement(a);
+          TEST_CHECK(ARR_GetSize(a) == s + 1);
+          memset(el1, s % 256, es);
+          TEST_CHECK(ARR_GetElement(a, s) == el1);
+          break;
+        case 1:
+          for (k = 0; k < s; k++) {
+            el1 = ARR_GetElement(a, k);
+            for (l = 0; l < es; l++)
+              TEST_CHECK(el1[l] == k % 256);
+          }
+          break;
+        case 2:
+          if (s == 0)
+            break;
+          TEST_CHECK(ARR_GetElements(a) == ARR_GetElement(a, 0));
+          break;
+        case 3:
+          memset(el2, s % 256, es);
+          ARR_AppendElement(a, el2);
+          TEST_CHECK(ARR_GetSize(a) == s + 1);
+          break;
+        case 4:
+          if (s == 0)
+            break;
+          k2 = random() % s;
+          ARR_RemoveElement(a, k2);
+          TEST_CHECK(ARR_GetSize(a) == s - 1);
+          for (k = k2; k < s - 1; k++) {
+            el1 = ARR_GetElement(a, k);
+            for (l = 0; l < es; l++) {
+              TEST_CHECK(el1[l] == (k + 1) % 256);
+              el1[l] = k % 256;
+            }
+          }
+          break;
+        case 5:
+          k2 = random() % 1000;
+          ARR_SetSize(a, k2);
+          TEST_CHECK(ARR_GetSize(a) == k2);
+          for (k = s; k < k2; k++) {
+            el1 = ARR_GetElement(a, k);
+            for (l = 0; l < es; l++)
+              el1[l] = k % 256;
+          }
+          break;
+        default:
+          assert(0);
+      }
+    }
+
+    ARR_DestroyInstance(a);
+  }
+}
diff --git a/test/unit/clientlog.c b/test/unit/clientlog.c
new file mode 100644
index 0000000..e5bf1f4
--- /dev/null
+++ b/test/unit/clientlog.c
@@ -0,0 +1,298 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_NTP) || defined(FEAT_CMDMON)
+
+#include <clientlog.c>
+
+static uint64_t
+get_random64(void)
+{
+  return ((uint64_t)random() << 40) ^ ((uint64_t)random() << 20) ^ random();
+}
+
+void
+test_unit(void)
+{
+  uint64_t ts64, prev_first_ts64, prev_last_ts64, max_step;
+  uint32_t index2, prev_first, prev_size;
+  NTP_Timestamp_Source ts_src, ts_src2;
+  struct timespec ts, ts2;
+  int i, j, k, index, shift;
+  CLG_Service s;
+  NTP_int64 ntp_ts;
+  IPAddr ip;
+  char conf[][100] = {
+    "clientloglimit 20000",
+    "ratelimit interval 3 burst 4 leak 3",
+    "cmdratelimit interval 3 burst 4 leak 3",
+    "ntsratelimit interval 6 burst 8 leak 3",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  CLG_Initialise();
+
+  TEST_CHECK(ARR_GetSize(records) == 16);
+
+  for (i = 0; i < 500; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    ts.tv_sec = (time_t)random() & 0x0fffffff;
+    ts.tv_nsec = 0;
+
+    for (j = 0; j < 1000; j++) {
+      TST_GetRandomAddress(&ip, IPADDR_UNSPEC, i % 8 ? -1 : i / 8 % 9);
+      DEBUG_LOG("address %s", UTI_IPToString(&ip));
+
+      s = random() % MAX_SERVICES;
+      index = CLG_LogServiceAccess(s, &ip, &ts);
+      TEST_CHECK(index >= 0);
+      CLG_LimitServiceRate(s, index);
+
+      UTI_AddDoubleToTimespec(&ts, (1 << random() % 14) / 100.0, &ts);
+    }
+  }
+
+  DEBUG_LOG("records %u", ARR_GetSize(records));
+  TEST_CHECK(ARR_GetSize(records) == 128);
+
+  s = CLG_NTP;
+
+  for (i = j = 0; i < 10000; i++) {
+    ts.tv_sec += 1;
+    index = CLG_LogServiceAccess(s, &ip, &ts);
+    TEST_CHECK(index >= 0);
+    if (!CLG_LimitServiceRate(s, index))
+      j++;
+  }
+
+  DEBUG_LOG("requests %d responses %d", i, j);
+  TEST_CHECK(j * 4 < i && j * 6 > i);
+
+  TEST_CHECK(!ntp_ts_map.timestamps);
+
+  UTI_ZeroNtp64(&ntp_ts);
+  CLG_SaveNtpTimestamps(&ntp_ts, NULL, 0);
+  TEST_CHECK(ntp_ts_map.timestamps);
+  TEST_CHECK(ntp_ts_map.first == 0);
+  TEST_CHECK(ntp_ts_map.size == 0);
+  TEST_CHECK(ntp_ts_map.max_size == 128);
+  TEST_CHECK(ARR_GetSize(ntp_ts_map.timestamps) == ntp_ts_map.max_size);
+
+  TEST_CHECK(ntp_ts_map.max_size > NTPTS_INSERT_LIMIT);
+
+  for (i = 0; i < 200; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    max_step = (1ULL << (i % 50));
+    ts64 = 0ULL - 100 * max_step;
+
+    if (i > 150)
+      ntp_ts_map.max_size = 1U << (i % 8);
+    assert(ntp_ts_map.max_size <= 128);
+    ntp_ts_map.first = i % ntp_ts_map.max_size;
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+    ntp_ts_map.slew_epoch = i * 400;
+
+    for (j = 0; j < 500; j++) {
+      do {
+        ts64 += get_random64() % max_step + 1;
+      } while (ts64 == 0ULL);
+
+      int64_to_ntp64(ts64, &ntp_ts);
+
+      if (random() % 10) {
+        UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+        UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
+      } else {
+        UTI_ZeroTimespec(&ts);
+      }
+
+      ts_src = random() % (MAX_NTP_TS + 1);
+      CLG_SaveNtpTimestamps(&ntp_ts,
+                            UTI_IsZeroTimespec(&ts) ? (random() % 2 ? &ts : NULL) : &ts,
+                            ts_src);
+
+      if (j < ntp_ts_map.max_size) {
+        TEST_CHECK(ntp_ts_map.size == j + 1);
+        TEST_CHECK(ntp_ts_map.first == i % ntp_ts_map.max_size);
+      } else {
+        TEST_CHECK(ntp_ts_map.size == ntp_ts_map.max_size);
+        TEST_CHECK(ntp_ts_map.first == (i + j + ntp_ts_map.size + 1) % ntp_ts_map.max_size);
+      }
+      TEST_CHECK(ntp_ts_map.cached_index == ntp_ts_map.size - 1);
+      TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->slew_epoch == ntp_ts_map.slew_epoch);
+      TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2, &ts_src2));
+      TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+      TEST_CHECK(UTI_IsZeroTimespec(&ts) || ts_src == ts_src2);
+
+      for (k = random() % 4; k > 0; k--) {
+        index2 = random() % ntp_ts_map.size;
+        int64_to_ntp64(get_ntp_tss(index2)->rx_ts, &ntp_ts);
+        if (random() % 2)
+          TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+
+        UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+        UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
+
+        ts2 = ts;
+        CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+        if ((get_ntp_tss(index2)->slew_epoch + 1) % (1U << 16) != ntp_ts_map.slew_epoch) {
+          TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+        } else {
+          TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - ntp_ts_map.slew_offset) <
+                     1.0e-9);
+        }
+
+        ts_src = random() % (MAX_NTP_TS + 1);
+        CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts, ts_src);
+
+        TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2, &ts_src2));
+        TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+        TEST_CHECK(ts_src == ts_src2);
+
+        if (random() % 2) {
+          uint16_t prev_epoch = ntp_ts_map.slew_epoch;
+          handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e-5, 1.0e-5),
+                      LCL_ChangeAdjust, NULL);
+          TEST_CHECK((prev_epoch + 1) % (1U << 16) == ntp_ts_map.slew_epoch);
+        }
+
+        if (ntp_ts_map.size > 1) {
+          index = random() % (ntp_ts_map.size - 1);
+          if (get_ntp_tss(index)->rx_ts + 1 != get_ntp_tss(index + 1)->rx_ts) {
+            int64_to_ntp64(get_ntp_tss(index)->rx_ts + 1, &ntp_ts);
+            TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+            int64_to_ntp64(get_ntp_tss(index + 1)->rx_ts - 1, &ntp_ts);
+            TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+            CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts, ts_src);
+            CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+          }
+        }
+
+        if (random() % 2) {
+          int64_to_ntp64(get_ntp_tss(0)->rx_ts - 1, &ntp_ts);
+          TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+          int64_to_ntp64(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts + 1, &ntp_ts);
+          TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+          CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts, ts_src);
+          CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+        }
+      }
+    }
+
+    for (j = 0; j < 500; j++) {
+      shift = (i % 3) * 26;
+
+      if (i % 7 == 0) {
+        while (ntp_ts_map.size < ntp_ts_map.max_size) {
+          ts64 += get_random64() >> (shift + 8);
+          int64_to_ntp64(ts64, &ntp_ts);
+          CLG_SaveNtpTimestamps(&ntp_ts, NULL, 0);
+          if (ntp_ts_map.cached_index + NTPTS_INSERT_LIMIT < ntp_ts_map.size)
+            ts64 = get_ntp_tss(ntp_ts_map.size - 1)->rx_ts;
+        }
+      }
+      do {
+        if (ntp_ts_map.size > 1 && random() % 2) {
+          k = random() % (ntp_ts_map.size - 1);
+          ts64 = get_ntp_tss(k)->rx_ts +
+                 (get_ntp_tss(k + 1)->rx_ts - get_ntp_tss(k)->rx_ts) / 2;
+        } else {
+          ts64 = get_random64() >> shift;
+        }
+      } while (ts64 == 0ULL);
+
+      int64_to_ntp64(ts64, &ntp_ts);
+
+      prev_first = ntp_ts_map.first;
+      prev_size = ntp_ts_map.size;
+      prev_first_ts64 = get_ntp_tss(0)->rx_ts;
+      prev_last_ts64 = get_ntp_tss(prev_size - 1)->rx_ts;
+      CLG_SaveNtpTimestamps(&ntp_ts, NULL, 0);
+
+      TEST_CHECK(find_ntp_rx_ts(ts64, &index2));
+
+      if (ntp_ts_map.size > 1) {
+        TEST_CHECK(ntp_ts_map.size > 0 && ntp_ts_map.size <= ntp_ts_map.max_size);
+        if (get_ntp_tss(index2)->flags & NTPTS_DISABLED)
+          continue;
+
+        TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts - ts64 <= NTPTS_FUTURE_LIMIT);
+
+        if ((int64_t)(prev_last_ts64 - ts64) <= NTPTS_FUTURE_LIMIT) {
+          TEST_CHECK(prev_size + 1 >= ntp_ts_map.size);
+          if (index2 + NTPTS_INSERT_LIMIT + 1 >= ntp_ts_map.size &&
+              !(index2 == 0 && NTPTS_INSERT_LIMIT < ntp_ts_map.max_size &&
+                ((NTPTS_INSERT_LIMIT == prev_size && (int64_t)(ts64 - prev_first_ts64) > 0) ||
+                 (NTPTS_INSERT_LIMIT + 1 == prev_size && (int64_t)(ts64 - prev_first_ts64) < 0))))
+            TEST_CHECK((prev_first + prev_size + 1) % ntp_ts_map.max_size ==
+                       (ntp_ts_map.first + ntp_ts_map.size) % ntp_ts_map.max_size);
+          else
+            TEST_CHECK(prev_first + prev_size == ntp_ts_map.first + ntp_ts_map.size);
+        }
+
+        TEST_CHECK((int64_t)(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts -
+                             get_ntp_tss(0)->rx_ts) > 0);
+        for (k = 0; k + 1 < ntp_ts_map.size; k++)
+          TEST_CHECK((int64_t)(get_ntp_tss(k + 1)->rx_ts - get_ntp_tss(k)->rx_ts) > 0);
+      }
+
+      if (random() % 10 == 0) {
+        CLG_DisableNtpTimestamps(&ntp_ts);
+        TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+      }
+
+      for (k = random() % 10; k > 0; k--) {
+        ts64 = get_random64() >> shift;
+        int64_to_ntp64(ts64, &ntp_ts);
+        CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2);
+      }
+    }
+
+    if (random() % 2) {
+      handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e9, 1.0e9),
+                  LCL_ChangeUnknownStep, NULL);
+      TEST_CHECK(ntp_ts_map.size == 0);
+      TEST_CHECK(ntp_ts_map.cached_rx_ts == 0ULL);
+      TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts, &ts_src2));
+      CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts, ts_src);
+    }
+  }
+
+  CLG_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/cmac.c b/test/unit/cmac.c
new file mode 100644
index 0000000..be4ffbb
--- /dev/null
+++ b/test/unit/cmac.c
@@ -0,0 +1,109 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <cmac.h>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+#define MAX_KEY_LENGTH 64
+#define MAX_HASH_LENGTH 64
+
+struct cmac_test {
+  const char *name;
+  const unsigned char key[MAX_KEY_LENGTH];
+  int key_length;
+  const unsigned char hash[MAX_HASH_LENGTH];
+  int hash_length;
+};
+
+void
+test_unit(void)
+{
+  unsigned char data[] = "abcdefghijklmnopqrstuvwxyz0123456789";
+  unsigned char hash[MAX_HASH_LENGTH];
+  struct cmac_test tests[] = {
+    { "AES128", "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16,
+                "\xaf\x3c\xfe\xc2\x66\x71\x08\x04\xd4\xaf\x5b\x16\x2b\x11\xf4\x85", 16 },
+    { "AES256", "\x14\x02\x8e\x7d\x17\x3c\x2f\x4e\x17\x0f\x37\x96\xc3\x2c\xc5\x99"
+                "\x18\xdd\x55\x23\xb7\xd7\x9b\xc5\x76\x36\x88\x3f\xc5\x82\xb5\x83", 32,
+                "\xfe\xf7\x94\x96\x14\x04\x11\x0b\x87\xe4\xd4\x3f\x81\xb3\xb2\x2d", 16 },
+    { "", "", 0, "", 0 }
+  };
+
+  CMC_Algorithm algorithm;
+  CMC_Instance inst;
+  int i, j, length;
+
+#ifndef HAVE_CMAC
+  TEST_REQUIRE(0);
+#endif
+
+  TEST_CHECK(CMC_INVALID == 0);
+
+  for (i = 0; tests[i].name[0] != '\0'; i++) {
+    algorithm = UTI_CmacNameToAlgorithm(tests[i].name);
+    TEST_CHECK(algorithm != 0);
+    TEST_CHECK(CMC_GetKeyLength(algorithm) == tests[i].key_length);
+
+    DEBUG_LOG("testing %s", tests[i].name);
+
+    for (j = -1; j <= 128; j++) {
+      if (j == tests[i].key_length)
+        continue;
+      TEST_CHECK(!CMC_CreateInstance(algorithm, tests[i].key, j));
+    }
+
+    inst = CMC_CreateInstance(algorithm, tests[i].key, tests[i].key_length);
+    TEST_CHECK(inst);
+
+    TEST_CHECK(!CMC_CreateInstance(0, tests[i].key, tests[i].key_length));
+
+    TEST_CHECK(CMC_Hash(inst, data, -1, hash, sizeof (hash)) == 0);
+    TEST_CHECK(CMC_Hash(inst, data, sizeof (data) - 1, hash, -1) == 0);
+
+    for (j = 0; j <= sizeof (hash); j++) {
+      memset(hash, 0, sizeof (hash));
+      length = CMC_Hash(inst, data, sizeof (data) - 1, hash, j);
+
+#if 0
+      for (int k = 0; k < length; k++)
+        printf("\\x%02x", hash[k]);
+      printf("\n");
+#endif
+
+      if (j >= tests[i].hash_length)
+        TEST_CHECK(length == tests[i].hash_length);
+      else
+        TEST_CHECK(length == j);
+
+      TEST_CHECK(!memcmp(hash, tests[i].hash, length));
+    }
+
+    for (j = 0; j < sizeof (data); j++) {
+      length = CMC_Hash(inst, data, j, hash, sizeof (hash));
+      TEST_CHECK(length == tests[i].hash_length);
+    }
+
+    CMC_DestroyInstance(inst);
+  }
+}
diff --git a/test/unit/hash.c b/test/unit/hash.c
new file mode 100644
index 0000000..2f9ffef
--- /dev/null
+++ b/test/unit/hash.c
@@ -0,0 +1,131 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <hash.h>
+#include <logging.h>
+#include <util.h>
+#include "test.h"
+
+struct hash_test {
+  const char *name;
+  const unsigned char out[MAX_HASH_LENGTH];
+  int length;
+};
+
+void
+test_unit(void)
+{
+  unsigned char data1[] = "abcdefghijklmnopqrstuvwxyz";
+  unsigned char data2[] = "12345678910";
+  unsigned char out[MAX_HASH_LENGTH];
+  struct hash_test tests[] = {
+    { "MD5-NC",    "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16 },
+    { "MD5",       "\xfc\x24\x97\x1b\x52\x66\xdc\x46\xef\xe0\xe8\x08\x46\x89\xb6\x88", 16 },
+    { "SHA1",      "\xd8\x85\xb3\x86\xce\xea\x93\xeb\x92\xcd\x7b\x94\xb9\x8d\xc2\x8e"
+                   "\x3e\x31\x13\xdd", 20},
+    { "SHA256",    "\x0e\x35\x14\xe7\x15\x7a\x1d\xdd\xea\x11\x78\xd3\x41\xf6\xb9\x3e"
+                   "\xa0\x42\x96\x73\x3c\x54\x74\x0b\xfa\x6b\x9e\x29\x59\xad\x69\xd3", 32 },
+    { "SHA384",    "\x2c\xeb\xbd\x4d\x95\xed\xad\x03\xed\x80\xc4\xf3\xa6\x10\x21\xde"
+                   "\x40\x69\x54\xed\x42\x70\xb8\x95\xb0\x6f\x01\x1d\x04\xdf\x57\xbc"
+                   "\x1d\xb5\x85\xbf\x4f\x03\x88\xd5\x83\x93\xbc\x81\x90\xb0\xa9\x9b", 48 },
+    { "SHA512",    "\x20\xba\xec\xcb\x68\x98\x33\x5b\x70\x26\x63\x13\xe2\xf7\x0e\x67"
+                   "\x08\xf3\x77\x4f\xbd\xeb\xc4\xa8\xc5\x94\xe2\x39\x40\x7e\xed\x0b"
+                   "\x69\x0e\x18\xa5\xa2\x03\x73\xe7\x1d\x20\x7d\x3f\xc8\x70\x2d\x64"
+                   "\x9e\x89\x6d\x20\x6a\x4a\x5a\x46\xe7\x4f\x2c\xf9\x0f\x0a\x54\xdc", 64 },
+    { "SHA3-224",  "\x3b\xa2\x22\x28\xdd\x26\x18\xec\x3b\xb9\x25\x39\x5e\xbd\x94\x25"
+                   "\xd4\x20\x8a\x76\x76\xc0\x3c\x5d\x9e\x0a\x06\x46", 28},
+    { "SHA3-256",  "\x26\xd1\x19\xb2\xc1\x64\xc8\xb8\x10\xd8\xa8\x1c\xb6\xa4\x0d\x29"
+                   "\x09\xc9\x8e\x2e\x2d\xde\x7a\x74\x8c\x43\x70\xb8\xaa\x0f\x09\x17", 32 },
+    { "SHA3-384",  "\x6a\x64\xb9\x89\x08\x29\xd0\xa7\x4b\x84\xba\xa6\x65\xf5\xe7\x54"
+                   "\xe2\x18\x12\xc3\x63\x34\xc6\xba\x26\xf5\x6e\x99\xe2\x54\xcc\x9d"
+                   "\x01\x10\x9d\xee\x35\x38\x04\x83\xe5\x71\x70\xd8\xc8\x99\x96\xd8", 48 },
+    { "SHA3-512",  "\xa8\xe3\x2b\x65\x1f\x87\x90\x73\x19\xc8\xa0\x3f\xe3\x85\x60\x3c"
+                   "\x39\xfc\xcb\xc1\x29\xe1\x23\x7d\x8b\x56\x54\xe3\x08\x9d\xf9\x74"
+                   "\x78\x69\x2e\x3c\x7e\x51\x1e\x9d\xab\x09\xbe\xe7\x6b\x1a\xa1\x22"
+                   "\x93\xb1\x2b\x82\x9d\x1e\xcf\xa8\x99\xc5\xec\x7b\x1d\x89\x07\x2b", 64 },
+    { "TIGER",     "\x1c\xcd\x68\x74\xca\xd6\xd5\x17\xba\x3e\x82\xaf\xbd\x70\xdc\x66"
+                   "\x99\xaa\xae\x16\x72\x59\xd1\x64", 24},
+    { "WHIRLPOOL", "\xe3\xcd\xe6\xbf\xe1\x8c\xe4\x4d\xc8\xb4\xa5\x7c\x36\x8d\xc8\x8a"
+                   "\x8b\xad\x52\x24\xc0\x4e\x99\x5b\x7e\x86\x94\x2d\x10\x56\x12\xa3"
+                   "\x29\x2a\x65\x0f\x9e\x07\xbc\x15\x21\x14\xe6\x07\xfc\xe6\xb9\x2f"
+                   "\x13\xe2\x57\xe9\x0a\xb0\xd2\xf4\xa3\x20\x36\x9c\x88\x92\x8e\xc9", 64 },
+    { "", "", 0 }
+  };
+
+  HSH_Algorithm algorithm;
+  int i, j, hash_id, length;
+
+  TEST_CHECK(HSH_INVALID == 0);
+
+  for (i = 0; tests[i].name[0] != '\0'; i++) {
+    algorithm = UTI_HashNameToAlgorithm(tests[i].name);
+    if (strcmp(tests[i].name, "MD5-NC") == 0) {
+      TEST_CHECK(algorithm == 0);
+      algorithm = HSH_MD5_NONCRYPTO;
+    } else {
+      TEST_CHECK(algorithm != 0);
+    }
+    hash_id = HSH_GetHashId(algorithm);
+    if (hash_id < 0) {
+      TEST_CHECK(algorithm != HSH_MD5_NONCRYPTO);
+      TEST_CHECK(algorithm != HSH_MD5);
+#ifdef FEAT_SECHASH
+      TEST_CHECK(algorithm != HSH_SHA1);
+      TEST_CHECK(algorithm != HSH_SHA256);
+      TEST_CHECK(algorithm != HSH_SHA384);
+      TEST_CHECK(algorithm != HSH_SHA512);
+#endif
+      continue;
+    }
+
+    DEBUG_LOG("testing %s", tests[i].name);
+
+    TEST_CHECK(HSH_Hash(hash_id, data1, -1, NULL, 0, out, sizeof (out)) == 0);
+    TEST_CHECK(HSH_Hash(hash_id, data1, sizeof (data1) - 1, data2, -1, out, sizeof (out)) == 0);
+    TEST_CHECK(HSH_Hash(hash_id, data1, sizeof (data1) - 1, NULL, 0, out, -1) == 0);
+
+    for (j = 0; j <= sizeof (out); j++) {
+      TEST_CHECK(HSH_GetHashId(algorithm) == hash_id);
+      TEST_CHECK(HSH_GetHashId(0) < 0);
+
+      memset(out, 0, sizeof (out));
+      length = HSH_Hash(hash_id, data1, sizeof (data1) - 1, data2, sizeof (data2) - 1,
+                        out, j);
+
+      if (j >= tests[i].length)
+        TEST_CHECK(length == tests[i].length);
+      else
+        TEST_CHECK(length == j);
+
+      TEST_CHECK(!memcmp(out, tests[i].out, length));
+    }
+
+    for (j = 0; j < 10000; j++) {
+      length = HSH_Hash(hash_id, data1, random() % sizeof (data1),
+                        random() % 2 ? data2 : NULL, random() % sizeof (data2),
+                        out, sizeof (out));
+      TEST_CHECK(length == tests[i].length);
+    }
+  }
+
+  HSH_Finalise();
+}
diff --git a/test/unit/hwclock.c b/test/unit/hwclock.c
new file mode 100644
index 0000000..79c0879
--- /dev/null
+++ b/test/unit/hwclock.c
@@ -0,0 +1,117 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016-2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_PHC) || defined(HAVE_LINUX_TIMESTAMPING)
+
+#include <hwclock.c>
+
+#define MAX_READINGS 20
+
+void
+test_unit(void)
+{
+  struct timespec start_hw_ts, start_local_ts, hw_ts, local_ts, ts;
+  struct timespec readings[MAX_READINGS][3];
+  HCL_Instance clock;
+  double freq, jitter, interval, dj, err, sum;
+  int i, j, k, l, new_sample, n_readings, count;
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+
+  for (i = 1; i <= 8; i++) {
+    clock = HCL_CreateInstance(random() % (1 << i), 1 << i, 1.0, 1e-9);
+
+    for (j = 0, count = 0, sum = 0.0; j < 100; j++) {
+      UTI_ZeroTimespec(&start_hw_ts);
+      UTI_ZeroTimespec(&start_local_ts);
+      UTI_AddDoubleToTimespec(&start_hw_ts, TST_GetRandomDouble(0.0, 1e9), &start_hw_ts);
+      UTI_AddDoubleToTimespec(&start_local_ts, TST_GetRandomDouble(0.0, 1e9), &start_local_ts);
+
+      DEBUG_LOG("iteration %d", j);
+
+      freq = TST_GetRandomDouble(0.9, 1.1);
+      jitter = TST_GetRandomDouble(10.0e-9, 1000.0e-9);
+      interval = TST_GetRandomDouble(0.1, 10.0);
+
+      clock->n_samples = 0;
+      clock->valid_coefs = 0;
+      QNT_Reset(clock->delay_quants);
+
+      new_sample = 0;
+
+      for (k = 0; k < 100; k++) {
+        UTI_AddDoubleToTimespec(&start_hw_ts, k * interval * freq, &hw_ts);
+        UTI_AddDoubleToTimespec(&start_local_ts, k * interval, &local_ts);
+        if (HCL_CookTime(clock, &hw_ts, &ts, NULL) && new_sample) {
+          dj = fabs(UTI_DiffTimespecsToDouble(&ts, &local_ts) / jitter);
+          DEBUG_LOG("delta/jitter %f", dj);
+          if (clock->n_samples >= clock->max_samples / 2)
+            sum += dj, count++;
+          TEST_CHECK(clock->n_samples < 4 || dj <= 4.0);
+          TEST_CHECK(clock->n_samples < 8 || dj <= 3.0);
+        }
+
+        UTI_AddDoubleToTimespec(&start_hw_ts, k * interval * freq + TST_GetRandomDouble(-jitter, jitter), &hw_ts);
+
+        if (HCL_NeedsNewSample(clock, &local_ts)) {
+          n_readings = random() % MAX_READINGS + 1;
+          for (l = 0; l < n_readings; l++) {
+            UTI_AddDoubleToTimespec(&local_ts, -TST_GetRandomDouble(0.0, jitter / 10.0), &readings[l][0]);
+            readings[l][1] = hw_ts;
+            UTI_AddDoubleToTimespec(&local_ts, TST_GetRandomDouble(0.0, jitter / 10.0), &readings[l][2]);
+          }
+
+          UTI_ZeroTimespec(&hw_ts);
+          UTI_ZeroTimespec(&local_ts);
+          if (HCL_ProcessReadings(clock, n_readings, readings, &hw_ts, &local_ts, &err)) {
+            HCL_AccumulateSample(clock, &hw_ts, &local_ts, 2.0 * jitter);
+            new_sample = 1;
+          } else {
+            new_sample = 0;
+          }
+        }
+
+        TEST_CHECK(clock->valid_coefs == (clock->n_samples >= 2));
+
+        if (!clock->valid_coefs)
+          continue;
+
+        TEST_CHECK(fabs(clock->offset) <= 2.0 * jitter);
+      }
+    }
+
+    TEST_CHECK(sum / count < 2.4 / sqrt(clock->max_samples));
+
+    HCL_DestroyInstance(clock);
+  }
+
+  LCL_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/keys.c b/test/unit/keys.c
new file mode 100644
index 0000000..aa5e649
--- /dev/null
+++ b/test/unit/keys.c
@@ -0,0 +1,173 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#if defined(FEAT_NTP) || defined(FEAT_CMDMON)
+
+#include <keys.c>
+
+#define KEYS 100
+#define KEYFILE "keys.test-keys"
+
+static
+uint32_t write_random_key(FILE *f)
+{
+  const char *type, *prefix;
+  char key[128];
+  uint32_t id;
+  int i, length;
+
+  length = random() % sizeof (key) + 1;
+  length = MAX(length, 4);
+  prefix = random() % 2 ? "HEX:" : "";
+
+  switch (random() % 8) {
+#ifdef FEAT_SECHASH
+    case 0:
+      type = "SHA1";
+      break;
+    case 1:
+      type = "SHA256";
+      break;
+    case 2:
+      type = "SHA384";
+      break;
+    case 3:
+      type = "SHA512";
+      break;
+#endif
+#ifdef HAVE_CMAC
+    case 4:
+      type = "AES128";
+      length = prefix[0] == '\0' ? 8 : 16;
+      break;
+    case 5:
+      type = "AES256";
+      length = prefix[0] == '\0' ? 16 : 32;
+      break;
+#endif
+    case 6:
+      type = "MD5";
+      break;
+    default:
+      type = "";
+  }
+
+  UTI_GetRandomBytes(&id, sizeof (id));
+  UTI_GetRandomBytes(key, length);
+
+  fprintf(f, "%u %s %s", id, type, prefix);
+  for (i = 0; i < length; i++)
+    fprintf(f, "%02hhX", key[i]);
+  fprintf(f, "\n");
+
+  return id;
+}
+
+static void
+generate_key_file(const char *name, uint32_t *keys)
+{
+  FILE *f;
+  int i;
+
+  f = fopen(name, "w");
+  TEST_CHECK(f);
+  for (i = 0; i < KEYS; i++)
+    keys[i] = write_random_key(f);
+  fclose(f);
+}
+
+void
+test_unit(void)
+{
+  int i, j, data_len, auth_len, type, bits;
+  uint32_t keys[KEYS], key;
+  unsigned char data[100], auth[MAX_HASH_LENGTH];
+  char conf[][100] = {
+    "keyfile "KEYFILE
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  generate_key_file(KEYFILE, keys);
+  KEY_Initialise();
+
+  for (i = 0; i < 100; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    if (i) {
+      generate_key_file(KEYFILE, keys);
+      KEY_Reload();
+    }
+
+    UTI_GetRandomBytes(data, sizeof (data));
+
+    for (j = 0; j < KEYS; j++) {
+      TEST_CHECK(KEY_KeyKnown(keys[j]));
+      TEST_CHECK(KEY_GetAuthLength(keys[j]) >= 16);
+
+      data_len = random() % (sizeof (data) + 1);
+      auth_len = KEY_GenerateAuth(keys[j], data, data_len, auth, sizeof (auth));
+      TEST_CHECK(auth_len >= 16);
+
+      TEST_CHECK(KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      if (j > 0 && keys[j - 1] != keys[j])
+        TEST_CHECK(!KEY_CheckAuth(keys[j - 1], data, data_len, auth, auth_len, auth_len));
+
+      auth_len = random() % auth_len + 1;
+      if (auth_len < MAX_HASH_LENGTH)
+        auth[auth_len]++;
+      TEST_CHECK(KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      auth[auth_len - 1]++;
+      TEST_CHECK(!KEY_CheckAuth(keys[j], data, data_len, auth, auth_len, auth_len));
+
+      TEST_CHECK(KEY_GetKeyInfo(keys[j], &type, &bits));
+      TEST_CHECK(type > 0 && bits > 0);
+    }
+
+    for (j = 0; j < 1000; j++) {
+      UTI_GetRandomBytes(&key, sizeof (key));
+      if (KEY_KeyKnown(key))
+        continue;
+      TEST_CHECK(!KEY_GetKeyInfo(key, &type, &bits));
+      TEST_CHECK(!KEY_GenerateAuth(key, data, data_len, auth, sizeof (auth)));
+      TEST_CHECK(!KEY_CheckAuth(key, data, data_len, auth, auth_len, auth_len));
+    }
+  }
+
+  unlink(KEYFILE);
+
+  KEY_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_auth.c b/test/unit/ntp_auth.c
new file mode 100644
index 0000000..5f2a9bc
--- /dev/null
+++ b/test/unit/ntp_auth.c
@@ -0,0 +1,289 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <conf.h>
+#include <keys.h>
+#include <local.h>
+#include <ntp_ext.h>
+#include <ntp_signd.h>
+#include <nts_ntp_server.h>
+#include <socket.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <ntp_auth.c>
+
+static void
+prepare_packet(NTP_AuthMode auth_mode, NTP_Packet *packet, NTP_PacketInfo *info, int req)
+{
+  unsigned char buf[64];
+  int i, version;
+  NTP_Mode mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      version = 3;
+      mode = random() % 2 ? (req ? MODE_CLIENT : MODE_SERVER) :
+                            (req ? MODE_ACTIVE : MODE_PASSIVE);
+      break;
+    case NTP_AUTH_NTS:
+      version = 4;
+      mode = req ? MODE_CLIENT : MODE_SERVER;
+      break;
+    default:
+      version = 3 + random() % 2;
+      mode = random() % 2 ? (req ? MODE_CLIENT : MODE_SERVER) :
+                            (req ? MODE_ACTIVE : MODE_PASSIVE);
+      break;
+  }
+
+  memset(packet, 0, sizeof (*packet));
+  memset(info, 0, sizeof (*info));
+  packet->lvm = NTP_LVM(LEAP_Normal, version, mode);
+  info->length = NTP_HEADER_LENGTH;
+  info->version = version;
+  info->mode = mode;
+
+  if (version == 4) {
+    memset(buf, 0, sizeof (buf));
+    for (i = random() % 5; i > 0; i--)
+      TEST_CHECK(NEF_AddField(packet, info, 0, buf, sizeof (buf)));
+  }
+}
+
+static void
+add_dummy_auth(NTP_AuthMode auth_mode, uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  unsigned char buf[64];
+  int len, fill;
+
+  info->auth.mode = auth_mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      switch (auth_mode) {
+        case NTP_AUTH_SYMMETRIC:
+          len = 16 + random() % 2 * 4;
+          fill = 1 + random() % 255;
+          break;
+        case NTP_AUTH_MSSNTP:
+          len = 16;
+          fill = 0;
+          break;
+        case NTP_AUTH_MSSNTP_EXT:
+          len = 68;
+          fill = 0;
+          break;
+        default:
+          assert(0);
+      }
+
+      assert(info->length + 4 + len <= sizeof (*packet));
+
+      *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+      info->auth.mac.key_id = key_id;
+      info->length += 4;
+
+      memset((unsigned char *)packet + info->length, fill, len);
+      info->length += len;
+      break;
+    case NTP_AUTH_NTS:
+      memset(buf, 0, sizeof (buf));
+      TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, buf, sizeof (buf)));
+      break;
+    default:
+      assert(0);
+  }
+}
+
+void
+test_unit(void)
+{
+  int i, j, can_auth_req, can_auth_res;
+  NTP_PacketInfo req_info, res_info;
+  NTP_Packet req, res;
+  NAU_Instance inst;
+  RPT_AuthReport report;
+  NTP_AuthMode mode;
+  IPSockAddr nts_addr;
+  uint32_t key_id, kod;
+  char conf[][100] = {
+    "keyfile ntp_core.keys"
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  KEY_Initialise();
+  NSD_Initialise();
+  NNS_Initialise();
+
+  SCK_GetAnyLocalIPAddress(IPADDR_INET4, &nts_addr.ip_addr);
+  nts_addr.port = 0;
+
+  for (i = 0; i < 1000; i++) {
+    key_id = INACTIVE_AUTHKEY;
+
+    switch (i % 5) {
+      case 0:
+        inst = NAU_CreateNoneInstance();
+        TEST_CHECK(!NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) == 4);
+        mode = NTP_AUTH_NONE;
+        can_auth_req = 1;
+        can_auth_res = 1;
+        break;
+      case 1:
+        key_id = random() % 7 + 2;
+        inst = NAU_CreateSymmetricInstance(key_id);
+        TEST_CHECK(NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) ==
+                   (KEY_KeyKnown(inst->key_id) && KEY_GetAuthLength(inst->key_id) > 20 ? 3 : 4));
+        mode = NTP_AUTH_SYMMETRIC;
+        can_auth_req = KEY_KeyKnown(key_id);
+        can_auth_res = can_auth_req;
+        break;
+      case 2:
+        inst = NAU_CreateNtsInstance(&nts_addr, "test", 0, 0);
+        TEST_CHECK(NAU_IsAuthEnabled(inst));
+        TEST_CHECK(NAU_GetSuggestedNtpVersion(inst) == 4);
+        mode = NTP_AUTH_NTS;
+        can_auth_req = 0;
+        can_auth_res = 0;
+        break;
+      case 3:
+        key_id = 1 + random() % 100;
+        inst = NULL;
+        mode = NTP_AUTH_MSSNTP;
+        can_auth_req = 1;
+        can_auth_res = 0;
+        break;
+      case 4:
+        key_id = 1 + random() % 100;
+        inst = NULL;
+        mode = NTP_AUTH_MSSNTP_EXT;
+        can_auth_req = 0;
+        can_auth_res = 0;
+        break;
+      default:
+        assert(0);
+    }
+
+    DEBUG_LOG("iteration %d auth=%d key_id=%d", i, (int)mode, (int)key_id);
+
+    prepare_packet(mode, &req, &req_info, 1);
+
+    if (inst) {
+      TEST_CHECK(inst->mode == mode);
+      TEST_CHECK(inst->key_id == key_id);
+
+      NAU_DumpData(inst);
+      NAU_GetReport(inst, &report);
+      if (random() % 2)
+        NAU_ChangeAddress(inst, &nts_addr.ip_addr);
+
+      if (inst->mode == NTP_AUTH_NTS) {
+        for (j = random() % 5; j > 0; j--)
+#ifdef FEAT_NTS
+          TEST_CHECK(!NAU_PrepareRequestAuth(inst));
+#else
+          TEST_CHECK(NAU_PrepareRequestAuth(inst));
+#endif
+        TEST_CHECK(!NAU_GenerateRequestAuth(inst, &req, &req_info));
+      } else if (can_auth_req) {
+        TEST_CHECK(NAU_PrepareRequestAuth(inst));
+        TEST_CHECK(NAU_GenerateRequestAuth(inst, &req, &req_info));
+      } else {
+        TEST_CHECK(NAU_PrepareRequestAuth(inst));
+        TEST_CHECK(!NAU_GenerateRequestAuth(inst, &req, &req_info));
+      }
+    }
+
+    if (!inst || !can_auth_req)
+      add_dummy_auth(mode, key_id, &req, &req_info);
+
+    assert(req_info.auth.mode == mode);
+    assert(req_info.auth.mac.key_id == key_id);
+
+    kod = 1;
+    TEST_CHECK(NAU_CheckRequestAuth(&req, &req_info, &kod) == can_auth_req);
+    TEST_CHECK(kod == 0);
+
+    if (inst) {
+      for (j = NTP_AUTH_NONE; j <= NTP_AUTH_NTS; j++) {
+        if (j == mode && j == NTP_AUTH_NONE)
+          continue;
+
+        prepare_packet(j, &res, &res_info, 0);
+        add_dummy_auth(j, key_id ? key_id : 1, &res, &res_info);
+
+        TEST_CHECK(res_info.auth.mode == j);
+        TEST_CHECK(!NAU_CheckResponseAuth(inst, &res, &res_info));
+      }
+    }
+
+    prepare_packet(mode, &res, &res_info, 0);
+    TEST_CHECK(NAU_GenerateResponseAuth(&req, &req_info, &res, &res_info, NULL, NULL, kod) ==
+               can_auth_res);
+    if (!can_auth_res)
+      add_dummy_auth(mode, key_id, &res, &res_info);
+
+    assert(res_info.auth.mode == mode);
+    assert(res_info.auth.mac.key_id == key_id);
+
+    if (inst) {
+      if (mode == NTP_AUTH_SYMMETRIC) {
+        res_info.auth.mac.key_id ^= 1;
+        TEST_CHECK(!NAU_CheckResponseAuth(inst, &res, &res_info));
+        res_info.auth.mac.key_id ^= 1;
+      }
+
+      TEST_CHECK(NAU_CheckResponseAuth(inst, &res, &res_info) == can_auth_res);
+
+      NAU_GetReport(inst, &report);
+      NAU_DestroyInstance(inst);
+    }
+  }
+
+  NNS_Finalise();
+  NSD_Finalise();
+  KEY_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_core.c b/test/unit/ntp_core.c
new file mode 100644
index 0000000..08a1532
--- /dev/null
+++ b/test/unit/ntp_core.c
@@ -0,0 +1,648 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017-2018, 2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <cmdparse.h>
+#include <conf.h>
+#include <keys.h>
+#include <ntp_ext.h>
+#include <ntp_io.h>
+#include <sched.h>
+#include <local.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+static struct timespec current_time;
+static NTP_Packet req_buffer, res_buffer;
+static int req_length, res_length;
+
+#define NIO_IsHwTsEnabled() 1
+#define NIO_OpenServerSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 100 : 0)
+#define NIO_CloseServerSocket(fd) assert(fd == 100)
+#define NIO_OpenClientSocket(addr) ((addr)->ip_addr.family != IPADDR_UNSPEC ? 101 : 0)
+#define NIO_CloseClientSocket(fd) assert(fd == 101)
+#define NIO_IsServerSocket(fd) (fd == 100)
+#define NIO_IsServerSocketOpen() 1
+#define NIO_SendPacket(msg, to, from, len, process_tx) (memcpy(&req_buffer, msg, len), req_length = len, 1)
+#define SCH_AddTimeoutByDelay(delay, handler, arg) (1 ? 102 : (handler(arg), 1))
+#define SCH_AddTimeoutInClass(delay, separation, randomness, class, handler, arg) \
+  add_timeout_in_class(delay, separation, randomness, class, handler, arg)
+#define SCH_RemoveTimeout(id) assert(!id || id == 102)
+#define LCL_ReadRawTime(ts) (*ts = current_time)
+#define LCL_ReadCookedTime(ts, err) do {double *p = err; *ts = current_time; if (p) *p = 0.0;} while (0)
+#define LCL_GetSysPrecisionAsLog() (random() % 10 - 30)
+#define SRC_UpdateReachability(inst, reach)
+#define SRC_ResetReachability(inst)
+
+static SCH_TimeoutID
+add_timeout_in_class(double min_delay, double separation, double randomness,
+                     SCH_TimeoutClass class, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg)
+{
+  return 102;
+}
+
+#include <ntp_core.c>
+
+static void
+advance_time(double x)
+{
+  UTI_AddDoubleToTimespec(&current_time, x, &current_time);
+}
+
+static uint32_t
+get_random_key_id(void)
+{
+  uint32_t id;
+
+  do {
+    id = random() % 8 + 2;
+  } while (!KEY_KeyKnown(id));
+
+  return id;
+}
+
+static void
+send_request(NCR_Instance inst, int late_hwts)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  uint32_t prev_tx_count;
+
+  prev_tx_count = inst->report.total_tx_count;
+
+  transmit_timeout(inst);
+  TEST_CHECK(!inst->valid_rx);
+  TEST_CHECK(prev_tx_count + 1 == inst->report.total_tx_count);
+
+  advance_time(1e-5);
+
+  if (random() % 2) {
+    local_addr.ip_addr.family = IPADDR_UNSPEC;
+    local_addr.if_index = INVALID_IF_INDEX;
+    local_addr.sock_fd = 101;
+    local_ts.ts = current_time;
+    local_ts.err = 0.0;
+    local_ts.source = NTP_TS_KERNEL;
+
+    NCR_ProcessTxKnown(inst, &local_addr, &local_ts, &req_buffer, req_length);
+  }
+
+  if (late_hwts) {
+    inst->report.total_good_count++;
+  } else {
+    inst->report.total_good_count = 0;
+  }
+}
+
+static void
+process_request(NTP_Remote_Address *remote_addr)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = 100;
+  local_ts.ts = current_time;
+  local_ts.err = 0.0;
+  local_ts.source = NTP_TS_KERNEL;
+
+  res_length = 0;
+  NCR_ProcessRxUnknown(remote_addr, &local_addr, &local_ts,
+                       &req_buffer, req_length);
+  res_length = req_length;
+  res_buffer = req_buffer;
+
+  advance_time(1e-5);
+
+  if (random() % 2) {
+    local_ts.ts = current_time;
+    NCR_ProcessTxUnknown(remote_addr, &local_addr, &local_ts,
+                         &res_buffer, res_length);
+  }
+}
+
+static void
+send_response(int interleaved, int authenticated, int allow_update, int valid_ts, int valid_auth)
+{
+  NTP_Packet *req, *res;
+  uint32_t key_id = 0;
+  int i, auth_len = 0, ef_len, efs;
+
+  req = &req_buffer;
+  res = &res_buffer;
+
+  TEST_CHECK(req_length >= NTP_HEADER_LENGTH);
+
+  res->lvm = NTP_LVM(LEAP_Normal, NTP_LVM_TO_VERSION(req->lvm),
+                     NTP_LVM_TO_MODE(req->lvm) == MODE_CLIENT ? MODE_SERVER : MODE_ACTIVE);
+  res->stratum = 1;
+  res->poll = req->poll;
+  res->precision = -20;
+  res->root_delay = UTI_DoubleToNtp32(0.1);
+  res->root_dispersion = UTI_DoubleToNtp32(0.1);
+  res->reference_id = 0;
+  UTI_ZeroNtp64(&res->reference_ts);
+  res->originate_ts = interleaved ? req->receive_ts : req->transmit_ts;
+
+  advance_time(TST_GetRandomDouble(1e-4, 1e-2));
+  UTI_TimespecToNtp64(&current_time, &res->receive_ts, NULL);
+  advance_time(TST_GetRandomDouble(-1e-4, 1e-3));
+  UTI_TimespecToNtp64(&current_time, &res->transmit_ts, NULL);
+  advance_time(TST_GetRandomDouble(1e-4, 1e-2));
+
+  if (!valid_ts) {
+    switch (random() % (allow_update ? 4 : 5)) {
+      case 0:
+        res->originate_ts.hi = random();
+        break;
+      case 1:
+        res->originate_ts.lo = random();
+        break;
+      case 2:
+        UTI_ZeroNtp64(&res->originate_ts);
+        break;
+      case 3:
+        UTI_ZeroNtp64(&res->receive_ts);
+        break;
+      case 4:
+        UTI_ZeroNtp64(&res->transmit_ts);
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  res_length = NTP_HEADER_LENGTH;
+
+  if (NTP_LVM_TO_VERSION(res->lvm) == 4 && random() % 2) {
+    unsigned char buf[128];
+
+    memset(buf, 0, sizeof (buf));
+    efs = random() % 5;
+
+    for (i = 0; i < efs; i++) {
+      ef_len = (i + 1 == efs ? NTP_MAX_V4_MAC_LENGTH + 4 : NTP_MIN_EF_LENGTH) +
+               4 * (random() % 10);
+      TEST_CHECK(NEF_SetField((unsigned char *)res, sizeof (*res), res_length, 0,
+                              buf, ef_len - 4, &ef_len));
+      res_length += ef_len;
+    }
+  }
+
+  if (authenticated) {
+    key_id = ntohl(*(uint32_t *)req->extensions);
+    if (key_id == 0)
+      key_id = get_random_key_id();
+    auth_len = KEY_GetAuthLength(key_id);
+    assert(auth_len);
+    if (NTP_LVM_TO_VERSION(res->lvm) == 4)
+      auth_len = MIN(auth_len, NTP_MAX_V4_MAC_LENGTH - 4);
+
+    if (KEY_GenerateAuth(key_id, res, res_length,
+                         (unsigned char *)res + res_length + 4, auth_len) != auth_len)
+      assert(0);
+    res_length += 4 + auth_len;
+  }
+
+  if (!valid_auth && authenticated) {
+    assert(auth_len);
+
+    switch (random() % 5) {
+      case 0:
+        key_id++;
+        break;
+      case 1:
+        key_id ^= 1;
+        if (KEY_GenerateAuth(key_id, res, res_length - auth_len - 4,
+                             (unsigned char *)res + res_length - auth_len, auth_len) != auth_len)
+          assert(0);
+        break;
+      case 2:
+        ((unsigned char *)res)[res_length - auth_len + random() % auth_len]++;
+        break;
+      case 3:
+        res_length -= 4 + auth_len;
+        auth_len = 4 * (random() % (auth_len / 4));
+        res_length += 4 + auth_len;
+        break;
+      case 4:
+        if (NTP_LVM_TO_VERSION(res->lvm) == 4 && random() % 2 &&
+            KEY_GetAuthLength(key_id) > NTP_MAX_V4_MAC_LENGTH - 4) {
+          res_length -= 4 + auth_len;
+          auth_len += 4 + 4 * (random() %
+                               ((KEY_GetAuthLength(key_id) - NTP_MAX_V4_MAC_LENGTH - 4) / 4));
+          if (KEY_GenerateAuth(key_id, res, res_length,
+                               (unsigned char *)res + res_length + 4, auth_len) != auth_len)
+              assert(0);
+          res_length += 4 + auth_len;
+        } else {
+          memset((unsigned char *)res + res_length, 0, 4);
+          auth_len += 4;
+          res_length += 4;
+        }
+        break;
+      default:
+        assert(0);
+    }
+  }
+
+  assert(res_length <= sizeof (*res));
+  assert(res_length >= NTP_HEADER_LENGTH + auth_len);
+
+  if (authenticated)
+    *(uint32_t *)((unsigned char *)res + res_length - auth_len - 4) = htonl(key_id);
+}
+
+static void
+proc_response(NCR_Instance inst, int good, int valid, int updated_sync,
+              int updated_init, int save)
+{
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  NTP_Packet *res;
+  uint32_t prev_rx_count, prev_valid_count;
+  struct timespec prev_rx_ts, prev_init_rx_ts;
+  int ret;
+
+  res = &res_buffer;
+
+  local_addr.ip_addr.family = IPADDR_UNSPEC;
+  local_addr.if_index = INVALID_IF_INDEX;
+  local_addr.sock_fd = NTP_LVM_TO_MODE(res->lvm) != MODE_SERVER ? 100 : 101;
+  local_ts.ts = current_time;
+  local_ts.err = 0.0;
+  local_ts.source = NTP_TS_KERNEL;
+
+  prev_rx_count = inst->report.total_rx_count;
+  prev_valid_count = inst->report.total_valid_count;
+  prev_rx_ts = inst->local_rx.ts;
+  prev_init_rx_ts = inst->init_local_rx.ts;
+
+  ret = NCR_ProcessRxKnown(inst, &local_addr, &local_ts, res, res_length);
+
+  if (save) {
+    TEST_CHECK(ret);
+    TEST_CHECK(inst->saved_response);
+    TEST_CHECK(inst->saved_response->timeout_id != 0);
+    TEST_CHECK(has_saved_response(inst));
+    if (random() % 2)
+      saved_response_timeout(inst);
+    else
+      transmit_timeout(inst);
+    TEST_CHECK(inst->saved_response->timeout_id == 0);
+    TEST_CHECK(!has_saved_response(inst));
+  }
+
+  if (good > 0)
+    TEST_CHECK(ret);
+  else if (!good)
+    TEST_CHECK(!ret);
+
+  TEST_CHECK(prev_rx_count + 1 == inst->report.total_rx_count);
+
+  if (valid)
+    TEST_CHECK(prev_valid_count + 1 == inst->report.total_valid_count);
+  else
+    TEST_CHECK(prev_valid_count == inst->report.total_valid_count);
+
+  if (updated_sync)
+    TEST_CHECK(UTI_CompareTimespecs(&inst->local_rx.ts, &prev_rx_ts));
+  else
+    TEST_CHECK(!UTI_CompareTimespecs(&inst->local_rx.ts, &prev_rx_ts));
+
+  if (updated_init > 0)
+    TEST_CHECK(UTI_CompareTimespecs(&inst->init_local_rx.ts, &prev_init_rx_ts));
+  else if (!updated_init)
+    TEST_CHECK(!UTI_CompareTimespecs(&inst->init_local_rx.ts, &prev_init_rx_ts));
+
+  if (valid) {
+    TEST_CHECK(UTI_IsZeroTimespec(&inst->init_local_rx.ts));
+    TEST_CHECK(UTI_IsZeroNtp64(&inst->init_remote_ntp_tx));
+  }
+}
+
+static void
+process_replay(NCR_Instance inst, NTP_Packet *packet_queue,
+               int queue_length, int updated_init)
+{
+  do {
+    res_buffer = packet_queue[random() % queue_length];
+  } while (!UTI_CompareNtp64(&res_buffer.transmit_ts, &inst->remote_ntp_tx));
+  proc_response(inst, 0, 0, 0, updated_init, 0);
+  advance_time(1e-6);
+}
+
+static void
+add_dummy_auth(NTP_AuthMode auth_mode, uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  unsigned char buf[64];
+  int len, fill;
+
+  info->auth.mode = auth_mode;
+
+  switch (auth_mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+    case NTP_AUTH_MSSNTP:
+    case NTP_AUTH_MSSNTP_EXT:
+      switch (auth_mode) {
+        case NTP_AUTH_SYMMETRIC:
+          len = 16 + random() % 2 * 4;
+          fill = 1 + random() % 255;
+          break;
+        case NTP_AUTH_MSSNTP:
+          len = 16;
+          fill = 0;
+          break;
+        case NTP_AUTH_MSSNTP_EXT:
+          len = 68;
+          fill = 0;
+          break;
+        default:
+          assert(0);
+      }
+
+      assert(info->length + 4 + len <= sizeof (*packet));
+
+      *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
+      info->auth.mac.key_id = key_id;
+      info->length += 4;
+
+      memset((unsigned char *)packet + info->length, fill, len);
+      info->length += len;
+      break;
+    case NTP_AUTH_NTS:
+      memset(buf, 0, sizeof (buf));
+      TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, buf, sizeof (buf)));
+      break;
+    default:
+      assert(0);
+  }
+}
+
+#define PACKET_QUEUE_LENGTH 10
+
+void
+test_unit(void)
+{
+  char source_line[] = "127.0.0.1 maxdelaydevratio 1e6 noselect";
+  char conf[][100] = {
+    "allow",
+    "port 0",
+    "local",
+    "keyfile ntp_core.keys"
+  };
+  int i, j, k, interleaved, authenticated, valid, updated, has_updated, late_hwts;
+  CPS_NTP_Source source;
+  NTP_Remote_Address remote_addr;
+  NCR_Instance inst1, inst2;
+  NTP_Packet packet_queue[PACKET_QUEUE_LENGTH], packet;
+  NTP_PacketInfo info;
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  REF_Initialise();
+  KEY_Initialise();
+  CLG_Initialise();
+
+  CNF_SetupAccessRestrictions();
+
+  CPS_ParseNTPSourceAdd(source_line, &source);
+
+  for (i = 0; i < 1000; i++) {
+    source.params.interleaved = random() % 2;
+    source.params.authkey = random() % 2 ? get_random_key_id() : INACTIVE_AUTHKEY;
+    source.params.version = random() % 4 + 1;
+
+    UTI_ZeroTimespec(&current_time);
+#if HAVE_LONG_TIME_T
+    advance_time(NTP_ERA_SPLIT);
+#endif
+    advance_time(TST_GetRandomDouble(1.0, 1e9));
+
+    TST_GetRandomAddress(&remote_addr.ip_addr, IPADDR_UNSPEC, -1);
+    remote_addr.port = 123;
+
+    inst1 = NCR_CreateInstance(&remote_addr, random() % 2 ? NTP_SERVER : NTP_PEER,
+                               &source.params, NULL);
+    NCR_StartInstance(inst1);
+    has_updated = 0;
+
+    for (j = 0; j < 50; j++) {
+      DEBUG_LOG("client/peer test iteration %d/%d", i, j);
+
+      late_hwts = random() % 2;
+      authenticated = random() % 2;
+      interleaved = random() % 2 && (inst1->mode != MODE_CLIENT ||
+                                     inst1->tx_count < MAX_CLIENT_INTERLEAVED_TX);
+      authenticated = random() % 2;
+      valid = (!interleaved || (source.params.interleaved && has_updated)) &&
+              ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
+      updated = (valid || inst1->mode == MODE_ACTIVE) &&
+                ((source.params.authkey == INACTIVE_AUTHKEY) == !authenticated);
+      has_updated = has_updated || updated;
+      if (inst1->mode == MODE_CLIENT)
+        updated = 0;
+
+      DEBUG_LOG("authkey=%d version=%d interleaved=%d authenticated=%d valid=%d updated=%d has_updated=%d",
+                (int)source.params.authkey, source.params.version,
+                interleaved, authenticated, valid, updated, has_updated);
+
+      send_request(inst1, late_hwts);
+
+      send_response(interleaved, authenticated, 1, 0, 1);
+      DEBUG_LOG("response 1");
+      proc_response(inst1, 0, 0, 0, updated, 0);
+
+      if (source.params.authkey) {
+        send_response(interleaved, authenticated, 1, 1, 0);
+        DEBUG_LOG("response 2");
+        proc_response(inst1, 0, 0, 0, 0, 0);
+      }
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 3");
+      proc_response(inst1, -1, valid, valid, updated, valid && late_hwts);
+      DEBUG_LOG("response 4");
+      proc_response(inst1, 0, 0, 0, 0, 0);
+
+      advance_time(-1.0);
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 5");
+      proc_response(inst1, 0, 0, 0, updated && valid, 0);
+
+      advance_time(1.0);
+
+      send_response(interleaved, authenticated, 1, 1, 1);
+      DEBUG_LOG("response 6");
+      proc_response(inst1, 0, 0, valid && updated, updated, 0);
+    }
+
+    NCR_DestroyInstance(inst1);
+
+    inst1 = NCR_CreateInstance(&remote_addr, random() % 2 ? NTP_SERVER : NTP_PEER,
+                               &source.params, NULL);
+    NCR_StartInstance(inst1);
+
+    for (j = 0; j < 20; j++) {
+      DEBUG_LOG("server test iteration %d/%d", i, j);
+
+      send_request(inst1, 0);
+      process_request(&remote_addr);
+      proc_response(inst1,
+                    !source.params.interleaved || source.params.version != 4 ||
+                      inst1->mode == MODE_ACTIVE || j != 2,
+                    1, 1, 0, 0);
+      advance_time(1 << inst1->local_poll);
+    }
+
+    NCR_DestroyInstance(inst1);
+
+    inst1 = NCR_CreateInstance(&remote_addr, NTP_PEER, &source.params, NULL);
+    NCR_StartInstance(inst1);
+    inst2 = NCR_CreateInstance(&remote_addr, NTP_PEER, &source.params, NULL);
+    NCR_StartInstance(inst2);
+
+    res_length = req_length = 0;
+
+    for (j = 0; j < 20; j++) {
+      DEBUG_LOG("peer replay test iteration %d/%d", i, j);
+
+      late_hwts = random() % 2;
+
+      send_request(inst1, late_hwts);
+      res_buffer = req_buffer;
+      assert(!res_length || res_length == req_length);
+      res_length = req_length;
+
+      TEST_CHECK(inst1->valid_timestamps == (j > 0));
+
+      DEBUG_LOG("response 1->2");
+      proc_response(inst2, j > source.params.interleaved, j > 0, j > 0, 1, 0);
+
+      packet_queue[(j * 2) % PACKET_QUEUE_LENGTH] = res_buffer;
+
+      for (k = 0; k < j % 4 + 1; k++) {
+        DEBUG_LOG("replay ?->1 %d", k);
+        process_replay(inst1, packet_queue, MIN(j * 2 + 1, PACKET_QUEUE_LENGTH), k ? -1 : 1);
+        DEBUG_LOG("replay ?->2 %d", k);
+        process_replay(inst2, packet_queue, MIN(j * 2 + 1, PACKET_QUEUE_LENGTH), -1);
+      }
+
+      advance_time(1 << (source.params.minpoll - 1));
+
+      send_request(inst2, 0);
+      res_buffer = req_buffer;
+      assert(res_length == req_length);
+
+      TEST_CHECK(inst2->valid_timestamps == (j > 0));
+
+      DEBUG_LOG("response 2->1");
+      proc_response(inst1, 1, 1, 1, 1, late_hwts);
+
+      packet_queue[(j * 2 + 1) % PACKET_QUEUE_LENGTH] = res_buffer;
+
+      for (k = 0; k < j % 4 + 1; k++) {
+        DEBUG_LOG("replay ?->1 %d", k);
+        process_replay(inst1, packet_queue, MIN(j * 2 + 2, PACKET_QUEUE_LENGTH), k ? -1 : 1);
+        DEBUG_LOG("replay ?->2 %d", k);
+        process_replay(inst2, packet_queue, MIN(j * 2 + 2, PACKET_QUEUE_LENGTH), -1);
+      }
+
+      advance_time(1 << (source.params.minpoll - 1));
+    }
+
+    NCR_DestroyInstance(inst1);
+    NCR_DestroyInstance(inst2);
+  }
+
+  memset(&packet, 0, sizeof (packet));
+  packet.lvm = NTP_LVM(LEAP_Normal, NTP_VERSION, MODE_CLIENT);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_NONE);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_SYMMETRIC, 100, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_SYMMETRIC);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == info.length - NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.key_id == 100);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_NTS, 0, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_NTS);
+
+  packet.lvm = NTP_LVM(LEAP_Normal, 3, MODE_CLIENT);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_MSSNTP, 200, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_MSSNTP);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == 20);
+  TEST_CHECK(info.auth.mac.key_id == 200);
+
+  TEST_CHECK(parse_packet(&packet, NTP_HEADER_LENGTH, &info));
+  add_dummy_auth(NTP_AUTH_MSSNTP_EXT, 300, &packet, &info);
+  memset(&info.auth, 0, sizeof (info.auth));
+  TEST_CHECK(parse_packet(&packet, info.length, &info));
+  TEST_CHECK(info.auth.mode == NTP_AUTH_MSSNTP_EXT);
+  TEST_CHECK(info.auth.mac.start == NTP_HEADER_LENGTH);
+  TEST_CHECK(info.auth.mac.length == 72);
+  TEST_CHECK(info.auth.mac.key_id == 300);
+
+  CLG_Finalise();
+  KEY_Finalise();
+  REF_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_core.keys b/test/unit/ntp_core.keys
new file mode 100644
index 0000000..a3e4f6c
--- /dev/null
+++ b/test/unit/ntp_core.keys
@@ -0,0 +1,8 @@
+2 MD5 HEX:38979C567358C0896F4D9D459A3C8B8478654579
+3 MD5 HEX:38979C567358C0896F4D9D459A3C8B8478654579
+4 SHA1 HEX:B71744EA01FBF01CA30D173ECDDF901952AE356A
+5 SHA1 HEX:B71744EA01FBF01CA30D173ECDDF901952AE356A
+6 SHA512 HEX:DE027482F22B201FC20863F58C74095E7906089F
+7 SHA512 HEX:DE027482F22B201FC20863F58C74095E7906089F
+8 AES128 HEX:5D5E8A31D4B459A66D445259E147CFB5
+9 AES128 HEX:5D5E8A31D4B459A66D445259E147CFB5
diff --git a/test/unit/ntp_ext.c b/test/unit/ntp_ext.c
new file mode 100644
index 0000000..c37e702
--- /dev/null
+++ b/test/unit/ntp_ext.c
@@ -0,0 +1,167 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <util.h>
+#include <logging.h>
+
+#include <ntp_ext.c>
+
+void
+test_unit(void)
+{
+  unsigned char *buffer, body[NTP_MAX_EXTENSIONS_LENGTH];
+  void *bodyp;
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  int i, j, start, length, type, type2, body_length, body_length2;
+
+  assert(sizeof (uint16_t) == 2);
+  assert(sizeof (body) == sizeof (packet.extensions));
+
+  buffer = (unsigned char *)packet.extensions;
+
+  for (i = 0; i < 10000; i++) {
+    body_length = random() % (sizeof (body) - 4 + 1) / 4 * 4;
+    start = random() % (sizeof (packet.extensions) - body_length - 4 + 1) / 4 * 4;
+    type = random() % 0x10000;
+
+    DEBUG_LOG("body_length=%d start=%d type=%d", body_length, start, type);
+    assert(body_length + start <= sizeof (packet.extensions));
+
+    UTI_GetRandomBytes(body, body_length);
+
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length + 4, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start + 4,
+                             type, body, body_length, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 1, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 2, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 4, start,
+                             type, body, body_length - 3, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 3, start,
+                             type, body, body_length, &length));
+    TEST_CHECK(!NEF_SetField(buffer, body_length + start + 5, start + 1,
+                             type, body, body_length, &length));
+
+    TEST_CHECK(NEF_SetField(buffer, body_length + start + 4, start,
+                            type, body, body_length, &length));
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(memcmp(buffer + start + 4, body, body_length) == 0);
+
+    memset(&packet, 0, sizeof (packet));
+    packet.lvm = NTP_LVM(0, 4, MODE_CLIENT);
+    memset(&info, 0, sizeof (info));
+
+    info.version = 3;
+    info.length = NTP_HEADER_LENGTH;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.version = 4;
+    info.length = NTP_HEADER_LENGTH - 4;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.length = sizeof (packet) - body_length;
+    TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+
+    info.length = NTP_HEADER_LENGTH + start;
+
+    if (body_length < 12) {
+      TEST_CHECK(!NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+      continue;
+    }
+
+    TEST_CHECK(NEF_AddBlankField(&packet, &info, type, body_length, &bodyp));
+    TEST_CHECK(info.length == NTP_HEADER_LENGTH + start + body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(info.ext_fields == 1);
+
+    memset(buffer, 0, sizeof (packet.extensions));
+    info.length = NTP_HEADER_LENGTH + start;
+    info.ext_fields = 0;
+
+    TEST_CHECK(NEF_AddField(&packet, &info, type, body, body_length));
+    TEST_CHECK(info.length == NTP_HEADER_LENGTH + start + body_length + 4);
+    TEST_CHECK(((uint16_t *)buffer)[start / 2] == htons(type));
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] == htons(length));
+    TEST_CHECK(memcmp(buffer + start + 4, body, body_length) == 0);
+    TEST_CHECK(info.ext_fields == 1);
+
+    for (j = 1; j <= 4; j++) {
+      TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] = htons(length + j));
+      TEST_CHECK(!NEF_ParseSingleField(buffer, start + body_length + 4, start,
+                                       &length, &type2, &bodyp, &body_length2));
+    }
+
+    TEST_CHECK(((uint16_t *)buffer)[start / 2 + 1] = htons(length));
+
+    TEST_CHECK(NEF_ParseSingleField(buffer, sizeof (packet.extensions), start,
+                                    &length, &type2, &bodyp, &body_length2));
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(type2 == type);
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(body_length2 == body_length);
+
+    TEST_CHECK(!NEF_ParseField(&packet, sizeof (packet) + 4,
+                               NTP_HEADER_LENGTH + start,
+                               &length, &type2, &bodyp, &body_length2));
+
+    if (body_length < 24) {
+      TEST_CHECK(!NEF_ParseField(&packet, NTP_HEADER_LENGTH + start + length, 
+                                 NTP_HEADER_LENGTH + start,
+                                 &length, &type2, &bodyp, &body_length2));
+      if (sizeof (packet.extensions) - start <= 24) {
+        TEST_CHECK(!NEF_ParseField(&packet, sizeof (packet), NTP_HEADER_LENGTH + start,
+                                   &length, &type2, &bodyp, &body_length2));
+        continue;
+      } else {
+        TEST_CHECK(NEF_ParseField(&packet, sizeof (packet), NTP_HEADER_LENGTH + start,
+                                  &length, &type2, &bodyp, &body_length2));
+      }
+    } else {
+      TEST_CHECK(NEF_ParseField(&packet, NTP_HEADER_LENGTH + start + length, 
+                                NTP_HEADER_LENGTH + start,
+                                &length, &type2, &bodyp, &body_length2));
+    }
+    TEST_CHECK(length == body_length + 4);
+    TEST_CHECK(type2 == type);
+    TEST_CHECK(bodyp == buffer + start + 4);
+    TEST_CHECK(body_length2 == body_length);
+
+  }
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/ntp_sources.c b/test/unit/ntp_sources.c
new file mode 100644
index 0000000..1626552
--- /dev/null
+++ b/test/unit/ntp_sources.c
@@ -0,0 +1,376 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTP
+
+#include <conf.h>
+#include <cmdparse.h>
+#include <nameserv_async.h>
+#include <ntp_core.h>
+#include <ntp_io.h>
+#include <sched.h>
+
+static char *requested_name = NULL;
+static DNS_NameResolveHandler resolve_handler = NULL;
+static void *resolve_handler_arg = NULL;
+
+#define DNS_Name2IPAddressAsync(name, handler, arg) \
+  requested_name = (name), \
+  resolve_handler = (handler), \
+  resolve_handler_arg = (arg)
+#define NCR_ChangeRemoteAddress(inst, remote_addr, ntp_only) \
+  change_remote_address(inst, remote_addr, ntp_only)
+#define NCR_ProcessRxKnown(remote_addr, local_addr, ts, msg, len) (random() % 2)
+#define NIO_IsServerConnectable(addr) (random() % 2)
+#define SCH_GetLastEventMonoTime() get_mono_time()
+
+static void change_remote_address(NCR_Instance inst, NTP_Remote_Address *remote_addr,
+                                  int ntp_only);
+static double get_mono_time(void);
+
+#include <ntp_sources.c>
+
+#undef NCR_ChangeRemoteAddress
+
+static void
+resolve_random_address(DNS_Status status, int rand_bits)
+{
+  IPAddr ip_addrs[DNS_MAX_ADDRESSES];
+  int i, n_addrs;
+
+  TEST_CHECK(requested_name);
+  requested_name = NULL;
+
+  if (status == DNS_Success) {
+    n_addrs = random() % DNS_MAX_ADDRESSES + 1;
+    for (i = 0; i < n_addrs; i++)
+      TST_GetRandomAddress(&ip_addrs[i], IPADDR_UNSPEC, rand_bits);
+  } else {
+    n_addrs = 0;
+  }
+
+  (resolve_handler)(status, n_addrs, ip_addrs, resolve_handler_arg);
+}
+
+static int
+update_random_address(NTP_Remote_Address *addr, int rand_bits)
+{
+  NTP_Remote_Address new_addr;
+  NSR_Status status;
+
+  TST_GetRandomAddress(&new_addr.ip_addr, IPADDR_UNSPEC, rand_bits);
+  new_addr.port = random() % 1024;
+
+  status = NSR_UpdateSourceNtpAddress(addr, &new_addr);
+  if (status == NSR_InvalidAF) {
+    TEST_CHECK(!UTI_IsIPReal(&addr->ip_addr));
+  } else {
+    TEST_CHECK(status == NSR_Success || status == NSR_AlreadyInUse);
+  }
+
+  return status == NSR_Success;
+}
+
+static void
+change_remote_address(NCR_Instance inst, NTP_Remote_Address *remote_addr, int ntp_only)
+{
+  int update = !ntp_only && random() % 4 == 0, update_pos = random() % 2, r = 0;
+
+  TEST_CHECK(record_lock);
+
+  if (update && update_pos == 0)
+    r = update_random_address(random() % 2 ? remote_addr : NCR_GetRemoteAddress(inst), 4);
+
+  NCR_ChangeRemoteAddress(inst, remote_addr, ntp_only);
+
+  if (update && update_pos == 1)
+    r = update_random_address(random() % 2 ? remote_addr : NCR_GetRemoteAddress(inst), 4);
+
+  if (r)
+    TEST_CHECK(UTI_IsIPReal(&saved_address_update.old_address.ip_addr));
+}
+
+static double get_mono_time(void) {
+  static double t = 0.0;
+
+  if (random() % 2)
+    t += TST_GetRandomDouble(0.0, 100.0);
+
+  return t;
+}
+
+void
+test_unit(void)
+{
+  char source_line[] = "127.0.0.1 offline", conf[] = "port 0", name[64];
+  int i, j, k, slot, found, pool, prev_n;
+  uint32_t hash = 0, conf_id;
+  NTP_Remote_Address addrs[256], addr;
+  NTP_Local_Address local_addr;
+  NTP_Local_Timestamp local_ts;
+  struct UnresolvedSource *us;
+  RPT_ActivityReport report;
+  CPS_NTP_Source source;
+  NSR_Status status;
+  NTP_Packet msg;
+
+  CNF_Initialise(0, 0);
+  CNF_ParseLine(NULL, 1, conf);
+
+  PRV_Initialise();
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  NIO_Initialise();
+  NCR_Initialise();
+  REF_Initialise();
+  NSR_Initialise();
+
+  CPS_ParseNTPSourceAdd(source_line, &source);
+
+  TEST_CHECK(n_sources == 0);
+
+  for (i = 0; i < 6; i++) {
+    TEST_CHECK(ARR_GetSize(records) == 1);
+
+    DEBUG_LOG("collision mod %u", 1U << i);
+
+    for (j = 0; j < sizeof (addrs) / sizeof (addrs[0]); j++) {
+      while (1) {
+        do {
+          TST_GetRandomAddress(&addrs[j].ip_addr, IPADDR_UNSPEC, -1);
+        } while (UTI_IPToHash(&addrs[j].ip_addr) % (1U << i) != hash % (1U << i));
+
+        for (k = 0; k < j; k++)
+          if (UTI_CompareIPs(&addrs[k].ip_addr, &addrs[j].ip_addr, NULL) == 0)
+            break;
+        if (k == j)
+          break;
+      }
+
+      addrs[j].port = random() % 1024;
+
+      if (!j)
+        hash = UTI_IPToHash(&addrs[j].ip_addr);
+
+      DEBUG_LOG("adding source %s hash %"PRIu32, UTI_IPToString(&addrs[j].ip_addr),
+                UTI_IPToHash(&addrs[j].ip_addr) % (1U << i));
+
+      status = NSR_AddSource(&addrs[j], random() % 2 ? NTP_SERVER : NTP_PEER,
+                             &source.params, NULL);
+      TEST_CHECK(status == NSR_Success);
+      TEST_CHECK(n_sources == j + 1);
+
+      TEST_CHECK(strcmp(NSR_GetName(&addrs[j].ip_addr), UTI_IPToString(&addrs[j].ip_addr)) == 0);
+
+      for (k = 0; k <= j; k++) {
+        addr = addrs[k];
+        found = find_slot2(&addr, &slot);
+        TEST_CHECK(found == 2);
+        TEST_CHECK(!UTI_CompareIPs(&get_record(slot)->remote_addr->ip_addr,
+                                   &addr.ip_addr, NULL));
+        addr.port++;
+        found = find_slot2(&addr, &slot);
+        TEST_CHECK(found == 1);
+        TEST_CHECK(!UTI_CompareIPs(&get_record(slot)->remote_addr->ip_addr,
+                                   &addr.ip_addr, NULL));
+      }
+
+      status = NSR_AddSource(&addrs[j], NTP_SERVER, &source.params, &conf_id);
+      TEST_CHECK(status == NSR_AlreadyInUse);
+    }
+
+    for (j = 0; j < sizeof (addrs) / sizeof (addrs[0]); j++) {
+      DEBUG_LOG("removing source %s", UTI_IPToString(&addrs[j].ip_addr));
+      NSR_RemoveSource(&addrs[j].ip_addr);
+
+      for (k = 0; k < sizeof (addrs) / sizeof (addrs[0]); k++) {
+        found = find_slot2(&addrs[k], &slot);
+        TEST_CHECK(found == (k <= j ? 0 : 2));
+      }
+    }
+  }
+
+  TEST_CHECK(n_sources == 0);
+
+  status = NSR_AddSourceByName("a b", 0, 0, 0, &source.params, &conf_id);
+  TEST_CHECK(status == NSR_InvalidName);
+
+  local_addr.ip_addr.family = IPADDR_INET4;
+  local_addr.ip_addr.addr.in4 = 0;
+  local_addr.if_index = -1;
+  local_addr.sock_fd = 0;
+  memset(&local_ts, 0, sizeof (local_ts));
+
+  for (i = 0; i < 500; i++) {
+    for (j = 0; j < 20; j++) {
+      snprintf(name, sizeof (name), "ntp%d.example.net", (int)(random() % 10));
+      pool = random() % 2;
+      prev_n = n_sources;
+
+      DEBUG_LOG("%d/%d adding source %s pool=%d", i, j, name, pool);
+      status = NSR_AddSourceByName(name, 0, pool, random() % 2 ? NTP_SERVER : NTP_PEER,
+                                   &source.params, &conf_id);
+      TEST_CHECK(status == NSR_UnresolvedName);
+
+      TEST_CHECK(n_sources == prev_n + (pool ? source.params.max_sources * 2 : 1));
+      TEST_CHECK(unresolved_sources);
+
+      for (us = unresolved_sources; us->next; us = us->next)
+        ;
+      TEST_CHECK(strcmp(us->name, name) == 0);
+      if (pool) {
+        TEST_CHECK(us->address.ip_addr.family == IPADDR_UNSPEC && us->pool_id >= 0);
+      } else {
+        TEST_CHECK(strcmp(NSR_GetName(&us->address.ip_addr), name) == 0);
+        TEST_CHECK(find_slot2(&us->address, &slot) == 2);
+      }
+
+      if (random() % 2) {
+        if (!resolving_id || random() % 2) {
+          NSR_ResolveSources();
+        } else {
+          SCH_RemoveTimeout(resolving_id);
+          resolve_sources_timeout(NULL);
+          TEST_CHECK(resolving_id == 0);
+          TEST_CHECK(requested_name);
+        }
+
+        TEST_CHECK(!!unresolved_sources == (resolving_id != 0) || requested_name);
+      }
+
+      while (requested_name && random() % 2) {
+        TEST_CHECK(resolving_source);
+        TEST_CHECK(strcmp(requested_name, resolving_source->name) == 0);
+        TEST_CHECK(!record_lock);
+
+        switch (random() % 3) {
+          case 0:
+            resolve_random_address(DNS_Success, 4);
+            break;
+          case 1:
+            resolve_random_address(DNS_TryAgain, 0);
+            break;
+          case 2:
+            resolve_random_address(DNS_Failure, 0);
+            break;
+        }
+      }
+
+      while (random() % 8 > 0) {
+        slot = random() % ARR_GetSize(records);
+        if (!get_record(slot)->remote_addr)
+          continue;
+
+        switch (random() % 5) {
+          case 0:
+            msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
+            NSR_ProcessTx(get_record(slot)->remote_addr, &local_addr,
+                          &local_ts, &msg, 0);
+            break;
+          case 1:
+            msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
+            NSR_ProcessRx(get_record(slot)->remote_addr, &local_addr,
+                          &local_ts, &msg, 0);
+            break;
+          case 2:
+            NSR_HandleBadSource(&get_record(slot)->remote_addr->ip_addr);
+            break;
+          case 3:
+            NSR_SetConnectivity(NULL, &get_record(slot)->remote_addr->ip_addr, SRC_OFFLINE);
+            break;
+          case 4:
+            update_random_address(get_record(slot)->remote_addr, 4);
+            TEST_CHECK(!UTI_IsIPReal(&saved_address_update.old_address.ip_addr));
+            break;
+        }
+
+        TEST_CHECK(!record_lock);
+      }
+
+      NSR_GetActivityReport(&report);
+      TEST_CHECK(report.online == 0);
+      TEST_CHECK(report.offline >= 0);
+      TEST_CHECK(report.burst_online == 0);
+      TEST_CHECK(report.burst_offline == 0);
+      TEST_CHECK(report.unresolved >= 0);
+
+      if (random() % 4 == 0) {
+        NSR_RemoveSourcesById(conf_id);
+        TEST_CHECK(n_sources <= prev_n);
+      } else if (random() % 8 == 0) {
+        NSR_RefreshAddresses();
+        TEST_CHECK(unresolved_sources);
+      }
+    }
+
+    NSR_RemoveAllSources();
+    TEST_CHECK(n_sources == 0);
+
+    for (j = 0; j < ARR_GetSize(pools); j++) {
+      TEST_CHECK(get_pool(j)->sources == 0);
+      TEST_CHECK(get_pool(j)->unresolved_sources == 0);
+      TEST_CHECK(get_pool(j)->confirmed_sources == 0);
+      TEST_CHECK(get_pool(j)->max_sources == 0);
+    }
+
+    while (requested_name) {
+      TEST_CHECK(resolving_source);
+      resolve_random_address(random() % 2 ? DNS_Success : DNS_TryAgain, 4);
+    }
+
+    if (unresolved_sources && resolving_id == 0)
+      NSR_ResolveSources();
+
+    TEST_CHECK(!!unresolved_sources == (resolving_id != 0));
+
+    if (resolving_id) {
+      SCH_RemoveTimeout(resolving_id);
+      resolve_sources_timeout(NULL);
+    }
+
+    TEST_CHECK(resolving_id == 0);
+    TEST_CHECK(!requested_name);
+    TEST_CHECK(!unresolved_sources);
+  }
+
+  NSR_Finalise();
+  REF_Finalise();
+  NCR_Finalise();
+  NIO_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  PRV_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
+
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke.crt b/test/unit/nts_ke.crt
new file mode 100644
index 0000000..8165287
--- /dev/null
+++ b/test/unit/nts_ke.crt
@@ -0,0 +1,8 @@
+-----BEGIN CERTIFICATE-----
+MIIBDjCBwaADAgECAgEBMAUGAytlcDAPMQ0wCwYDVQQDEwR0ZXN0MCAXDTcwMDEw
+MTAwMDAwMFoYDzIxMDAwMTAyMDAwMDAwWjAPMQ0wCwYDVQQDEwR0ZXN0MCowBQYD
+K2VwAyEA3oh/FZeOxRYvJVLfCDEwGI6Oe23gTgLHx8a87tvwgfyjQDA+MAwGA1Ud
+EwEB/wQCMAAwDwYDVR0PAQH/BAUDAweAADAdBgNVHQ4EFgQUYwAqF9q3jxUk68m1
+cuz8DueOHeMwBQYDK2VwA0EAne0dCRXb0dW8bn2v3RhVTqeTJWXfl74x8MTQMTM7
+/uGTqoYOA0YJffypd+p27pvx2BEoNQWRYM6pqBg55KbwDw==
+-----END CERTIFICATE-----
diff --git a/test/unit/nts_ke.key b/test/unit/nts_ke.key
new file mode 100644
index 0000000..6414c64
--- /dev/null
+++ b/test/unit/nts_ke.key
@@ -0,0 +1,25 @@
+Public Key Info:
+	Public Key Algorithm: EdDSA (Ed25519)
+	Key Security Level: High (256 bits)
+
+curve:	Ed25519
+private key:
+	01:d9:75:42:7c:52:cc:29:9e:90:01:f3:da:26:f6:d7
+	ad:af:a5:2a:82:36:1d:86:c6:57:a7:b4:99:9b:6c:6d
+	
+
+x:
+	de:88:7f:15:97:8e:c5:16:2f:25:52:df:08:31:30:18
+	8e:8e:7b:6d:e0:4e:02:c7:c7:c6:bc:ee:db:f0:81:fc
+	
+
+
+Public Key PIN:
+	pin-sha256:C4LBJP2cRxvLcZ6pjowcOEQhcW3ZPMVTpLgRGsBDeMw=
+Public Key ID:
+	sha256:0b82c124fd9c471bcb719ea98e8c1c384421716dd93cc553a4b8111ac04378cc
+	sha1:63002a17dab78f1524ebc9b572ecfc0ee78e1de3
+
+-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIAHZdUJ8UswpnpAB89om9tetr6UqgjYdhsZXp7SZm2xt
+-----END PRIVATE KEY-----
diff --git a/test/unit/nts_ke_client.c b/test/unit/nts_ke_client.c
new file mode 100644
index 0000000..3100d1d
--- /dev/null
+++ b/test/unit/nts_ke_client.c
@@ -0,0 +1,147 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ke_client.c>
+#include <local.h>
+
+static void
+prepare_response(NKSN_Instance session, int valid)
+{
+  uint16_t data[16];
+  int i, index, length;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 10;
+  DEBUG_LOG("index=%d", index);
+
+  NKSN_BeginMessage(session);
+
+  memset(data, 0, sizeof (data));
+  length = 2;
+  assert(sizeof (data[0]) == 2);
+
+  if (index == 0) {
+    data[0] = htons(random() % 100);
+    TEST_CHECK(NKSN_AddRecord(session, 1, random() % 2 ? NKE_RECORD_ERROR : NKE_RECORD_WARNING,
+                              data, length));
+  } else if (index == 1) {
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_ERROR + 1000, data, length));
+  }
+
+  if (index != 2) {
+    if (index == 3)
+      data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4 + random() % 10 + 1);
+    else
+      data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+    if (index == 4)
+      length = 3 + random() % 10;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+  }
+
+  if (index != 5) {
+    if (index == 6)
+      do {
+        data[0] = htons(random() % 100);
+      } while (SIV_GetKeyLength(ntohs(data[0])) > 0);
+    else
+      data[0] = htons(random() % 2 && SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0 ?
+                                      AEAD_AES_128_GCM_SIV : AEAD_AES_SIV_CMAC_256);
+    if (index == 7)
+      length = 3 + random() % 10;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+  }
+
+  if (random() % 2) {
+    const char server[] = "127.0.0.1";
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                              server, sizeof (server) - 1));
+  }
+
+  if (random() % 2) {
+    data[0] = htons(123);
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NTPV4_PORT_NEGOTIATION, data, length));
+  }
+
+  if (random() % 2) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 0, 1000 + random() % 1000, data, length));
+  }
+
+  if (index != 8) {
+    for (i = 0; i < NKE_MAX_COOKIES; i++) {
+      length = (random() % sizeof (data) + 1) / 4 * 4;
+      if (index == 9)
+        length += (length < sizeof (data) ? 1 : -1) * (random() % 3 + 1);
+      TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_COOKIE, data, length));
+    }
+  }
+
+  TEST_CHECK(NKSN_EndMessage(session));
+}
+
+void
+test_unit(void)
+{
+  NKC_Instance inst;
+  IPSockAddr addr;
+  int i, r, valid;
+
+  char conf[][100] = {
+    "nosystemcert",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+
+  SCK_GetLoopbackIPAddress(AF_INET, &addr.ip_addr);
+  addr.port = 0;
+
+  inst = NKC_CreateInstance(&addr, "test", 0);
+  TEST_CHECK(inst);
+
+  for (i = 0; i < 10000; i++) {
+    valid = random() % 2;
+    prepare_response(inst->session, valid);
+    r = process_response(inst);
+    TEST_CHECK(r == valid);
+  }
+
+  NKC_DestroyInstance(inst);
+
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke_server.c b/test/unit/nts_ke_server.c
new file mode 100644
index 0000000..3d2f295
--- /dev/null
+++ b/test/unit/nts_ke_server.c
@@ -0,0 +1,235 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <local.h>
+#include <nts_ke_session.h>
+#include <util.h>
+
+#define NKSN_GetKeys get_keys
+
+static int
+get_keys(NKSN_Instance session, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c)
+{
+  c2s->length = SIV_GetKeyLength(siv);
+  UTI_GetRandomBytes(c2s->key, c2s->length);
+  s2c->length = SIV_GetKeyLength(siv);
+  UTI_GetRandomBytes(s2c->key, s2c->length);
+  return 1;
+}
+
+#include <nts_ke_server.c>
+
+static void
+prepare_request(NKSN_Instance session, int valid)
+{
+  uint16_t data[16];
+  int index, length;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 9;
+  DEBUG_LOG("index=%d", index);
+
+  NKSN_BeginMessage(session);
+
+  memset(data, 0, sizeof (data));
+  length = 2;
+  assert(sizeof (data[0]) == 2);
+
+  if (index != 0) {
+    memset(data, NKE_NEXT_PROTOCOL_NTPV4 + 1, sizeof (data));
+    data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+    if (index == 1)
+      length = 0;
+    else if (index == 2)
+      length = 3 + random() % 15 * 2;
+    else
+      length = 2 + random() % 16 * 2;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+  }
+
+  if (index == 3)
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, length));
+
+  if (index != 4) {
+    data[0] = htons(random() % 2 && SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0 ?
+                    AEAD_AES_128_GCM_SIV : AEAD_AES_SIV_CMAC_256);
+    if (index == 5)
+      length = 0;
+    else if (index == 6)
+      length = 3 + random() % 15 * 2;
+    else
+      length = 2 + random() % 16 * 2;
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+  }
+
+  if (index == 7)
+    TEST_CHECK(NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data, length));
+
+  if (index == 8) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 1, 1000 + random() % 1000, data, length));
+  }
+
+  if (random() % 2) {
+    const char server[] = "127.0.0.1";
+    TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_NTPV4_SERVER_NEGOTIATION,
+                              server, sizeof (server) - 1));
+  }
+
+  if (random() % 2) {
+    data[0] = htons(123);
+    TEST_CHECK(NKSN_AddRecord(session, 0, NKE_RECORD_NTPV4_PORT_NEGOTIATION, data, length));
+  }
+
+  if (random() % 2) {
+    length = random() % (sizeof (data) + 1);
+    TEST_CHECK(NKSN_AddRecord(session, 0, 1000 + random() % 1000, data, length));
+  }
+
+  TEST_CHECK(NKSN_EndMessage(session));
+}
+
+static void
+process_response(NKSN_Instance session, int valid)
+{
+  int records, errors, critical, type, length;
+
+  for (records = errors = 0; ; records++) {
+    if (!NKSN_GetRecord(session, &critical, &type, &length, NULL, 0))
+      break;
+    if (type == NKE_RECORD_ERROR)
+      errors++;
+  }
+
+  if (valid) {
+    TEST_CHECK(records >= 2);
+  } else {
+    TEST_CHECK(records == 1);
+    TEST_CHECK(errors == 1);
+  }
+}
+
+void
+test_unit(void)
+{
+  NKSN_Instance session;
+  NKE_Context context, context2;
+  NKE_Cookie cookie;
+  int i, j, valid, l;
+  uint32_t sum, sum2;
+
+  char conf[][100] = {
+    "ntsdumpdir .",
+    "ntsport 0",
+    "ntsprocesses 0",
+    "ntsserverkey nts_ke.key",
+    "ntsservercert nts_ke.crt",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+
+  unlink("ntskeys");
+  NKS_PreInitialise(0, 0, 0);
+  NKS_Initialise();
+
+  session = NKSN_CreateInstance(1, NULL, handle_message, NULL);
+
+  for (i = 0; i < 10000; i++) {
+    valid = random() % 2;
+    prepare_request(session, valid);
+    TEST_CHECK(process_request(session));
+    process_response(session, valid);
+  }
+
+
+  for (i = 0; i < 10000; i++) {
+    context.algorithm = AEAD_AES_SIV_CMAC_256;
+    get_keys(session, context.algorithm, &context.c2s, &context.s2c);
+    memset(&cookie, 0, sizeof (cookie));
+    TEST_CHECK(NKS_GenerateCookie(&context, &cookie));
+    TEST_CHECK(NKS_DecodeCookie(&cookie, &context2));
+    TEST_CHECK(context.algorithm == context2.algorithm);
+    TEST_CHECK(context.c2s.length == context2.c2s.length);
+    TEST_CHECK(context.s2c.length == context2.s2c.length);
+    TEST_CHECK(memcmp(context.c2s.key, context2.c2s.key, context.c2s.length) == 0);
+    TEST_CHECK(memcmp(context.s2c.key, context2.s2c.key, context.s2c.length) == 0);
+
+    if (random() % 4) {
+      cookie.cookie[random() % (cookie.length)]++;
+    } else if (random() % 4) {
+      generate_key(current_server_key);
+    } else {
+      l = cookie.length;
+      while (l == cookie.length)
+        cookie.length = random() % (sizeof (cookie.cookie) + 1);
+    }
+    TEST_CHECK(!NKS_DecodeCookie(&cookie, &context2));
+  }
+
+  unlink("ntskeys");
+  save_keys();
+
+  for (i = 0, sum = 0; i < MAX_SERVER_KEYS; i++) {
+    sum += server_keys[i].id;
+    for (j = 0; j < sizeof (server_keys[i].key); j++)
+      sum += server_keys[i].key[j];
+    generate_key(i);
+  }
+
+  load_keys();
+  TEST_CHECK(unlink("ntskeys") == 0);
+
+  for (i = 0, sum2 = 0; i < MAX_SERVER_KEYS; i++) {
+    sum2 += server_keys[i].id;
+    for (j = 0; j < sizeof (server_keys[i].key); j++)
+      sum2 += server_keys[i].key[j];
+  }
+
+  TEST_CHECK(sum == sum2);
+
+  NKSN_DestroyInstance(session);
+
+  NKS_Finalise();
+  TEST_CHECK(unlink("ntskeys") == 0);
+
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ke_session.c b/test/unit/nts_ke_session.c
new file mode 100644
index 0000000..d0e72c7
--- /dev/null
+++ b/test/unit/nts_ke_session.c
@@ -0,0 +1,224 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ke_session.c>
+
+#include <local.h>
+#include <socket.h>
+#include <sched.h>
+
+static NKSN_Instance client, server;
+static unsigned char record[NKE_MAX_MESSAGE_LENGTH];
+static int record_length, critical, type_start, records;
+static int request_received;
+static int response_received;
+
+static void
+send_message(NKSN_Instance inst)
+{
+  int i;
+
+  record_length = random() % (NKE_MAX_MESSAGE_LENGTH - 4 + 1);
+  for (i = 0; i < record_length; i++)
+    record[i] = random() % 256;
+  critical = random() % 2;
+  type_start = random() % 30000 + 1;
+  assert(sizeof (struct RecordHeader) == 4);
+  records = random() % ((NKE_MAX_MESSAGE_LENGTH - 4) / (4 + record_length) + 1);
+
+  DEBUG_LOG("critical=%d type_start=%d records=%d*%d",
+            critical, type_start, records, record_length);
+
+  NKSN_BeginMessage(inst);
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(!check_message_format(&inst->message, 1));
+
+  TEST_CHECK(!NKSN_AddRecord(inst, 0, 1, record, NKE_MAX_MESSAGE_LENGTH - 4 + 1));
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(!check_message_format(&inst->message, 1));
+
+  for (i = 0; i < records; i++) {
+    TEST_CHECK(NKSN_AddRecord(inst, critical, type_start + i, record, record_length));
+    TEST_CHECK(!NKSN_AddRecord(inst, 0, 1, &record,
+                               NKE_MAX_MESSAGE_LENGTH - inst->message.length - 4 + 1));
+
+    TEST_CHECK(check_message_format(&inst->message, 0));
+    TEST_CHECK(!check_message_format(&inst->message, 1));
+  }
+
+  TEST_CHECK(NKSN_EndMessage(inst));
+
+  TEST_CHECK(check_message_format(&inst->message, 0));
+  TEST_CHECK(check_message_format(&inst->message, 1));
+}
+
+static void
+verify_message(NKSN_Instance inst)
+{
+  unsigned char buffer[NKE_MAX_MESSAGE_LENGTH];
+  int i, c, t, length, buffer_length, msg_length, prev_parsed;
+  NKE_Key c2s, s2c;
+
+  for (i = 0; i < records; i++) {
+    memset(buffer, 0, sizeof (buffer));
+    buffer_length = random() % (record_length + 1);
+    assert(buffer_length <= sizeof (buffer));
+
+    prev_parsed = inst->message.parsed;
+    msg_length = inst->message.length;
+
+    TEST_CHECK(NKSN_GetRecord(inst, &c, &t, &length, buffer, buffer_length));
+    TEST_CHECK(c == critical);
+    TEST_CHECK(t == type_start + i);
+    TEST_CHECK(length == record_length);
+    TEST_CHECK(memcmp(record, buffer, buffer_length) == 0);
+    if (buffer_length < record_length)
+      TEST_CHECK(buffer[buffer_length] == 0);
+
+    inst->message.length = inst->message.parsed - 1;
+    inst->message.parsed = prev_parsed;
+    TEST_CHECK(!get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+    TEST_CHECK(inst->message.parsed == prev_parsed);
+    inst->message.length = msg_length;
+    if (msg_length < 0x8000) {
+      inst->message.data[prev_parsed + 2] ^= 0x80;
+      TEST_CHECK(!get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+      TEST_CHECK(inst->message.parsed == prev_parsed);
+      inst->message.data[prev_parsed + 2] ^= 0x80;
+    }
+    TEST_CHECK(get_record(&inst->message, NULL, NULL, NULL, buffer, buffer_length));
+    TEST_CHECK(inst->message.parsed > prev_parsed);
+  }
+
+  TEST_CHECK(!NKSN_GetRecord(inst, &critical, &t, &length, buffer, sizeof (buffer)));
+
+  TEST_CHECK(NKSN_GetKeys(inst, AEAD_AES_SIV_CMAC_256, &c2s, &s2c));
+  TEST_CHECK(c2s.length == SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256));
+  TEST_CHECK(s2c.length == SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256));
+}
+
+static int
+handle_request(void *arg)
+{
+  NKSN_Instance server = arg;
+
+  verify_message(server);
+
+  request_received = 1;
+
+  send_message(server);
+
+  return 1;
+}
+
+static int
+handle_response(void *arg)
+{
+  NKSN_Instance client = arg;
+
+  response_received = 1;
+
+  verify_message(client);
+
+  return 1;
+}
+
+static void
+check_finished(void *arg)
+{
+  DEBUG_LOG("checking for stopped sessions");
+  if (!NKSN_IsStopped(server) || !NKSN_IsStopped(client)) {
+    SCH_AddTimeoutByDelay(0.001, check_finished, NULL);
+    return;
+  }
+
+  SCH_QuitProgram();
+}
+
+void
+test_unit(void)
+{
+  NKSN_Credentials client_cred, server_cred;
+  const char *cert, *key;
+  int sock_fds[2], i;
+  uint32_t cert_id;
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+
+  cert = "nts_ke.crt";
+  key = "nts_ke.key";
+  cert_id = 0;
+
+  for (i = 0; i < 50; i++) {
+    SCH_Initialise();
+
+    server = NKSN_CreateInstance(1, NULL, handle_request, NULL);
+    client = NKSN_CreateInstance(0, "test", handle_response, NULL);
+
+    server_cred = NKSN_CreateServerCertCredentials(&cert, &key, 1);
+    client_cred = NKSN_CreateClientCertCredentials(&cert, &cert_id, 1, 0);
+
+    TEST_CHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, sock_fds) == 0);
+    TEST_CHECK(fcntl(sock_fds[0], F_SETFL, O_NONBLOCK) == 0);
+    TEST_CHECK(fcntl(sock_fds[1], F_SETFL, O_NONBLOCK) == 0);
+
+    TEST_CHECK(NKSN_StartSession(server, sock_fds[0], "client", server_cred, 4.0));
+    TEST_CHECK(NKSN_StartSession(client, sock_fds[1], "server", client_cred, 4.0));
+
+    send_message(client);
+
+    request_received = response_received = 0;
+
+    check_finished(NULL);
+
+    SCH_MainLoop();
+
+    TEST_CHECK(NKSN_IsStopped(server));
+    TEST_CHECK(NKSN_IsStopped(client));
+
+    TEST_CHECK(request_received);
+    TEST_CHECK(response_received);
+
+    NKSN_DestroyInstance(server);
+    NKSN_DestroyInstance(client);
+
+    NKSN_DestroyCertCredentials(server_cred);
+    NKSN_DestroyCertCredentials(client_cred);
+
+    SCH_Finalise();
+  }
+
+  LCL_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_auth.c b/test/unit/nts_ntp_auth.c
new file mode 100644
index 0000000..c3a7432
--- /dev/null
+++ b/test/unit/nts_ntp_auth.c
@@ -0,0 +1,135 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <nts_ntp_auth.c>
+
+#include "ntp_ext.h"
+#include "siv.h"
+
+void
+test_unit(void)
+{
+  unsigned char key[SIV_MAX_KEY_LENGTH], nonce[256], plaintext[256], plaintext2[256];
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  SIV_Algorithm algo;
+  SIV_Instance siv;
+  int i, j, r, packet_length, nonce_length, key_length;
+  int plaintext_length, plaintext2_length, min_ef_length;
+
+  for (algo = 1; algo < 100; algo++) {
+    siv = SIV_CreateInstance(algo);
+    if (!siv) {
+      TEST_CHECK(algo != AEAD_AES_SIV_CMAC_256);
+      continue;
+    }
+
+    DEBUG_LOG("algo=%d", (int)algo);
+
+    for (i = 0; i < 10000; i++) {
+      key_length = SIV_GetKeyLength(algo);
+      for (j = 0; j < key_length; j++)
+        key[j] = random() % 256;
+      TEST_CHECK(SIV_SetKey(siv, key, key_length));
+
+      assert(sizeof (nonce) >= SIV_GetMinNonceLength(siv));
+      nonce_length = SIV_GetMinNonceLength(siv) +
+                     random() % (MIN(sizeof (nonce), SIV_GetMaxNonceLength(siv)) -
+                                 SIV_GetMinNonceLength(siv) + 1);
+      for (j = 0; j < nonce_length; j++)
+        nonce[j] = random() % 256;
+
+      plaintext_length = random() % (sizeof (plaintext) + 1);
+      for (j = 0; j < plaintext_length; j++)
+        plaintext[j] = random() % 256;
+
+      packet_length = NTP_HEADER_LENGTH + random() % 100 * 4;
+      min_ef_length = random() % (sizeof (packet) - packet_length);
+
+      memset(&packet, 0, sizeof (packet));
+      packet.lvm = NTP_LVM(0, 4, 0);
+      memset(&info, 0, sizeof (info));
+      info.version = 4;
+      info.length = packet_length;
+
+      DEBUG_LOG("packet_length=%d nonce_length=%d plaintext_length=%d min_ef_length=%d",
+                packet_length, nonce_length, plaintext_length, min_ef_length);
+
+      r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                             -1, 0);
+      TEST_CHECK(!r);
+      r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, 0, plaintext,
+                             plaintext_length, 0);
+      TEST_CHECK(!r);
+      if (SIV_GetMinNonceLength(siv) > 1) {
+        r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, SIV_GetMinNonceLength(siv) - 1,
+                               plaintext, plaintext_length, 0);
+        TEST_CHECK(!r);
+        TEST_CHECK(info.ext_fields == 0);
+      }
+      if (SIV_GetMaxNonceLength(siv) <= sizeof (nonce)) {
+        r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, SIV_GetMaxNonceLength(siv) - 1,
+                               plaintext, plaintext_length, 0);
+        TEST_CHECK(!r);
+        TEST_CHECK(info.ext_fields == 0);
+      }
+      r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                             plaintext_length, sizeof (packet) - info.length + 1);
+      TEST_CHECK(!r);
+
+      r = NNA_GenerateAuthEF(&packet, &info, siv, nonce, nonce_length, plaintext,
+                             plaintext_length, min_ef_length);
+      TEST_CHECK(r);
+      TEST_CHECK(info.length - packet_length >= min_ef_length);
+
+      r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                            -1, &plaintext2_length);
+      TEST_CHECK(!r);
+
+      r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                            sizeof (plaintext2), &plaintext2_length);
+      TEST_CHECK(r);
+      TEST_CHECK(plaintext_length == plaintext2_length);
+      TEST_CHECK(memcmp(plaintext, plaintext2, plaintext_length) == 0);
+
+      j = random() % (packet_length + plaintext_length +
+                      nonce_length + SIV_GetTagLength(siv) + 8) / 4 * 4;
+      ((unsigned char *)&packet)[j]++;
+      r = NNA_DecryptAuthEF(&packet, &info, siv, packet_length, plaintext2,
+                            sizeof (plaintext2), &plaintext2_length);
+      TEST_CHECK(!r);
+      ((unsigned char *)&packet)[j]--;
+    }
+
+    SIV_DestroyInstance(siv);
+  }
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_client.c b/test/unit/nts_ntp_client.c
new file mode 100644
index 0000000..7953413
--- /dev/null
+++ b/test/unit/nts_ntp_client.c
@@ -0,0 +1,302 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include "socket.h"
+#include "ntp.h"
+#include "nts_ke_client.h"
+
+#define NKC_CreateInstance(address, name, cert_set) Malloc(1)
+#define NKC_DestroyInstance(inst) Free(inst)
+#define NKC_Start(inst) (random() % 2)
+#define NKC_IsActive(inst) (random() % 2)
+#define NKC_GetRetryFactor(inst) (1)
+
+static int get_nts_data(NKC_Instance inst, NKE_Context *context,
+                        NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+                        IPSockAddr *ntp_address);
+#define NKC_GetNtsData get_nts_data
+
+#include <nts_ntp_client.c>
+
+static int
+get_nts_data(NKC_Instance inst, NKE_Context *context,
+             NKE_Cookie *cookies, int *num_cookies, int max_cookies,
+             IPSockAddr *ntp_address)
+{
+  int i;
+
+  if (random() % 2)
+    return 0;
+
+  do {
+    context->algorithm = AEAD_AES_SIV_CMAC_256 + random() %
+                         (AEAD_AES_256_GCM_SIV - AEAD_AES_SIV_CMAC_256 + 10);
+  } while (SIV_GetKeyLength(context->algorithm) <= 0);
+
+  context->c2s.length = SIV_GetKeyLength(context->algorithm);
+  UTI_GetRandomBytes(context->c2s.key, context->c2s.length);
+  context->s2c.length = SIV_GetKeyLength(context->algorithm);
+  UTI_GetRandomBytes(context->s2c.key, context->s2c.length);
+
+  *num_cookies = random() % max_cookies + 1;
+  for (i = 0; i < *num_cookies; i++) {
+    cookies[i].length = random() % (sizeof (cookies[i].cookie) + 1);
+    if (random() % 4 != 0)
+      cookies[i].length = cookies[i].length / 4 * 4;
+    memset(cookies[i].cookie, random(), cookies[i].length);
+  }
+
+  ntp_address->ip_addr.family = IPADDR_UNSPEC;
+  ntp_address->port = 0;
+
+  return 1;
+}
+
+static int
+get_request(NNC_Instance inst)
+{
+  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH], uniq_id[NTS_MIN_UNIQ_ID_LENGTH];
+  int nonce_length, expected_length, req_cookies;
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+
+  memset(&packet, 0, sizeof (packet));
+  memset(&info, 0, sizeof (info));
+  info.version = 4;
+  info.mode = MODE_CLIENT;
+  info.length = random() % (sizeof (packet) + 1);
+  if (random() % 4 != 0)
+    info.length = info.length / 4 * 4;
+
+  if (inst->num_cookies > 0 && random() % 2) {
+    inst->num_cookies = 0;
+
+    TEST_CHECK(!NNC_GenerateRequestAuth(inst, &packet, &info));
+  }
+
+  while (!NNC_PrepareForAuth(inst)) {
+    inst->next_nke_attempt = SCH_GetLastEventMonoTime() + random() % 10 - 7;
+  }
+
+  TEST_CHECK(inst->num_cookies > 0);
+  TEST_CHECK(inst->siv);
+
+  switch (inst->context.algorithm) {
+    case AEAD_AES_SIV_CMAC_256:
+      nonce_length = 16;
+      break;
+    case AEAD_AES_128_GCM_SIV:
+      nonce_length = 12;
+      break;
+    default:
+      assert(0);
+  }
+
+  memcpy(nonce, inst->nonce, sizeof (nonce));
+  memcpy(uniq_id, inst->uniq_id, sizeof (uniq_id));
+  TEST_CHECK(NNC_PrepareForAuth(inst));
+  TEST_CHECK(memcmp(nonce, inst->nonce, sizeof (nonce)) != 0);
+  TEST_CHECK(memcmp(uniq_id, inst->uniq_id, sizeof (uniq_id)) != 0);
+
+  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies + 1,
+                    MAX_TOTAL_COOKIE_LENGTH /
+                      (inst->cookies[inst->cookie_index].length + 4));
+  expected_length = info.length + 4 + sizeof (inst->uniq_id) +
+                    req_cookies * (4 + inst->cookies[inst->cookie_index].length) +
+                    4 + 4 + nonce_length + SIV_GetTagLength(inst->siv);
+  DEBUG_LOG("algo=%d length=%d cookie_length=%d expected_length=%d",
+            (int)inst->context.algorithm, info.length,
+            inst->cookies[inst->cookie_index].length, expected_length);
+
+  if (info.length % 4 == 0 && info.length >= NTP_HEADER_LENGTH &&
+      inst->cookies[inst->cookie_index].length % 4 == 0 &&
+      inst->cookies[inst->cookie_index].length >= (NTP_MIN_EF_LENGTH - 4) &&
+      expected_length <= sizeof (packet)) {
+    TEST_CHECK(NNC_GenerateRequestAuth(inst, &packet, &info));
+    TEST_CHECK(info.length == expected_length);
+    return 1;
+  } else {
+    TEST_CHECK(!NNC_GenerateRequestAuth(inst, &packet, &info));
+    return 0;
+  }
+}
+
+static void
+prepare_response(NNC_Instance inst, NTP_Packet *packet, NTP_PacketInfo *info, int valid, int nak)
+{
+  unsigned char cookie[508], plaintext[528], nonce[448];
+  int nonce_length, ef_length, cookie_length, plaintext_length, min_auth_length;
+  int i, index, auth_start;
+  SIV_Instance siv;
+
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_SERVER);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_SERVER;
+  info->length = NTP_HEADER_LENGTH;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % (nak ? 2 : 8);
+
+  DEBUG_LOG("index=%d nak=%d", index, nak);
+
+  if (index != 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER, inst->uniq_id,
+                            sizeof (inst->uniq_id)));
+  if (index == 1)
+    ((unsigned char *)packet)[NTP_HEADER_LENGTH + 4]++;
+
+  if (nak) {
+    packet->stratum = NTP_INVALID_STRATUM;
+    packet->reference_id = htonl(NTP_KOD_NTS_NAK);
+    return;
+  }
+
+  nonce_length = SIV_GetMinNonceLength(inst->siv) + random() %
+                 (MIN(SIV_GetMaxNonceLength(inst->siv), sizeof (nonce)) -
+                  SIV_GetMinNonceLength(inst->siv) + 1);
+  assert(nonce_length >= 1 && nonce_length <= sizeof (nonce));
+
+  do {
+    cookie_length = random() % (sizeof (cookie) + 1);
+  } while (cookie_length % 4 != 0 ||
+           ((index != 2) == (cookie_length < NTP_MIN_EF_LENGTH - 4 ||
+                             cookie_length > NKE_MAX_COOKIE_LENGTH)));
+
+  min_auth_length = random() % (512 + 1);
+
+  DEBUG_LOG("nonce_length=%d cookie_length=%d min_auth_length=%d",
+            nonce_length, cookie_length, min_auth_length);
+
+  UTI_GetRandomBytes(nonce, nonce_length);
+  UTI_GetRandomBytes(cookie, cookie_length);
+
+  if (cookie_length >= 12 && cookie_length <= 32 && random() % 2 == 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE, cookie, cookie_length));
+
+  plaintext_length = 0;
+  if (index != 3) {
+    for (i = random() % ((sizeof (plaintext) - 16) / (cookie_length + 4)); i >= 0; i--) {
+      TEST_CHECK(NEF_SetField(plaintext, sizeof (plaintext), plaintext_length,
+                              NTP_EF_NTS_COOKIE, cookie,
+                              i == 0 ? cookie_length : random() % (cookie_length + 1) / 4 * 4,
+                              &ef_length));
+      plaintext_length += ef_length;
+    }
+  }
+  auth_start = info->length;
+  if (index != 4) {
+    if (index == 5) {
+      assert(plaintext_length + 16 <= sizeof (plaintext));
+      memset(plaintext + plaintext_length, 0, 16);
+      plaintext_length += 16;
+    }
+    siv = SIV_CreateInstance(inst->context.algorithm);
+    TEST_CHECK(siv);
+    TEST_CHECK(SIV_SetKey(siv, inst->context.s2c.key, inst->context.s2c.length));
+    TEST_CHECK(NNA_GenerateAuthEF(packet, info, siv,
+                                  nonce, nonce_length, plaintext, plaintext_length,
+                                  min_auth_length));
+    SIV_DestroyInstance(siv);
+  }
+  if (index == 6)
+    ((unsigned char *)packet)[auth_start + 8]++;
+  if (index == 7)
+    TEST_CHECK(NEF_AddField(packet, info, 0x7000, inst->uniq_id, sizeof (inst->uniq_id)));
+}
+
+void
+test_unit(void)
+{
+  NNC_Instance inst;
+  NTP_PacketInfo info;
+  NTP_Packet packet;
+  IPSockAddr addr;
+  IPAddr ip_addr;
+  int i, j, prev_num_cookies, valid;
+
+  TEST_CHECK(SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) > 0);
+
+  SCK_GetLoopbackIPAddress(AF_INET, &addr.ip_addr);
+  addr.port = 0;
+
+  inst = NNC_CreateInstance(&addr, "test", 0, 0);
+  TEST_CHECK(inst);
+
+  for (i = 0; i < 100000; i++) {
+    if (!get_request(inst))
+      continue;
+
+    valid = random() % 2;
+
+    TEST_CHECK(!inst->nak_response);
+    TEST_CHECK(!inst->ok_response);
+
+    if (random() % 2) {
+      prepare_response(inst, &packet, &info, 0, 1);
+      TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+      TEST_CHECK(!inst->nak_response);
+      TEST_CHECK(!inst->ok_response);
+      for (j = random() % 3; j > 0; j--) {
+        prepare_response(inst, &packet, &info, 1, 1);
+        TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+        TEST_CHECK(inst->nak_response);
+        TEST_CHECK(!inst->ok_response);
+      }
+    }
+
+    prev_num_cookies = inst->num_cookies;
+    prepare_response(inst, &packet, &info, valid, 0);
+
+    if (valid) {
+      TEST_CHECK(NNC_CheckResponseAuth(inst, &packet, &info));
+      TEST_CHECK(inst->num_cookies >= MIN(NTS_MAX_COOKIES, prev_num_cookies + 1));
+      TEST_CHECK(inst->ok_response);
+    }
+
+    prev_num_cookies = inst->num_cookies;
+    TEST_CHECK(!NNC_CheckResponseAuth(inst, &packet, &info));
+    TEST_CHECK(inst->num_cookies == prev_num_cookies);
+    TEST_CHECK(inst->ok_response == valid);
+
+    if (random() % 10 == 0) {
+      TST_GetRandomAddress(&ip_addr, IPADDR_INET4, 32);
+      NNC_ChangeAddress(inst, &ip_addr);
+      TEST_CHECK(UTI_CompareIPs(&inst->nts_address.ip_addr, &ip_addr, NULL) == 0);
+    }
+  }
+
+  NNC_DestroyInstance(inst);
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/nts_ntp_server.c b/test/unit/nts_ntp_server.c
new file mode 100644
index 0000000..2777942
--- /dev/null
+++ b/test/unit/nts_ntp_server.c
@@ -0,0 +1,180 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2020
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include "test.h"
+
+#ifdef FEAT_NTS
+
+#include <local.h>
+#include <sched.h>
+
+#include <nts_ntp_server.c>
+
+static void
+prepare_request(NTP_Packet *packet, NTP_PacketInfo *info, int valid, int nak)
+{
+  unsigned char uniq_id[NTS_MIN_UNIQ_ID_LENGTH], nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
+  SIV_Instance siv;
+  NKE_Context context;
+  NKE_Cookie cookie;
+  int i, index, cookie_start, auth_start;
+
+  context.algorithm = random() % 2 && SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0 ?
+                      AEAD_AES_128_GCM_SIV : AEAD_AES_SIV_CMAC_256;
+  context.c2s.length = SIV_GetKeyLength(context.algorithm);
+  assert(context.c2s.length <= sizeof (context.c2s.key));
+  UTI_GetRandomBytes(&context.c2s.key, context.c2s.length);
+  context.s2c.length = SIV_GetKeyLength(context.algorithm);
+  assert(context.s2c.length <= sizeof (context.s2c.key));
+  UTI_GetRandomBytes(&context.s2c.key, context.s2c.length);
+
+  TEST_CHECK(NKS_GenerateCookie(&context, &cookie));
+
+  UTI_GetRandomBytes(uniq_id, sizeof (uniq_id));
+  UTI_GetRandomBytes(nonce, sizeof (nonce));
+
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_CLIENT);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_CLIENT;
+  info->length = NTP_HEADER_LENGTH;
+
+  if (valid)
+    index = -1;
+  else
+    index = random() % 3;
+
+  DEBUG_LOG("valid=%d nak=%d index=%d", valid, nak, index);
+
+  if (index != 0)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER,
+                            uniq_id, sizeof (uniq_id)));
+
+  cookie_start = info->length;
+
+  if (index != 1)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE,
+                            cookie.cookie, cookie.length));
+
+  for (i = random() % 4; i > 0; i--)
+    TEST_CHECK(NEF_AddField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
+                            cookie.cookie, cookie.length));
+
+  auth_start = info->length;
+
+  if (index != 2) {
+    siv = SIV_CreateInstance(context.algorithm);
+    TEST_CHECK(siv);
+    TEST_CHECK(SIV_SetKey(siv, context.c2s.key, context.c2s.length));
+    TEST_CHECK(NNA_GenerateAuthEF(packet, info, siv, nonce, sizeof (nonce),
+                                  (const unsigned char *)"", 0, 0));
+    SIV_DestroyInstance(siv);
+  }
+
+  if (nak)
+    ((unsigned char *)packet)[(index == 2 ? cookie_start :
+                               (index == 1 ? auth_start :
+                                (random() % 2 ? cookie_start : auth_start))) +
+                              4 + random() % 16]++;
+}
+
+static void
+init_response(NTP_Packet *packet, NTP_PacketInfo *info)
+{
+  memset(packet, 0, sizeof (*packet));
+  packet->lvm = NTP_LVM(0, 4, MODE_SERVER);
+  memset(info, 0, sizeof (*info));
+  info->version = 4;
+  info->mode = MODE_SERVER;
+  info->length = NTP_HEADER_LENGTH;
+}
+
+void
+test_unit(void)
+{
+  NTP_PacketInfo req_info, res_info;
+  NTP_Packet request, response;
+  int i, valid, nak;
+  uint32_t kod;
+
+  char conf[][100] = {
+    "ntsport 0",
+    "ntsprocesses 0",
+    "ntsserverkey nts_ke.key",
+    "ntsservercert nts_ke.crt",
+  };
+
+  CNF_Initialise(0, 0);
+  for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
+    CNF_ParseLine(NULL, i + 1, conf[i]);
+
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  NKS_PreInitialise(0, 0, 0);
+  NKS_Initialise();
+  NNS_Initialise();
+
+  for (i = 0; i < 50000; i++) {
+    valid = random() % 2;
+    nak = random() % 2;
+    prepare_request(&request, &req_info, valid, nak);
+
+    TEST_CHECK(NNS_CheckRequestAuth(&request, &req_info, &kod) == (valid && !nak));
+
+    if (valid && !nak) {
+      TEST_CHECK(kod == 0);
+      TEST_CHECK(server->num_cookies > 0);
+
+      init_response(&response, &res_info);
+      TEST_CHECK(NNS_GenerateResponseAuth(&request, &req_info, &response, &res_info, kod));
+
+      TEST_CHECK(res_info.ext_fields == 2);
+      TEST_CHECK(server->num_cookies == 0);
+    } else if (valid && nak) {
+      TEST_CHECK(kod == NTP_KOD_NTS_NAK);
+      TEST_CHECK(server->num_cookies == 0);
+
+      init_response(&response, &res_info);
+      TEST_CHECK(NNS_GenerateResponseAuth(&request, &req_info, &response, &res_info, kod));
+
+      TEST_CHECK(res_info.ext_fields == 1);
+      TEST_CHECK(server->num_cookies == 0);
+    } else {
+      TEST_CHECK(kod == 0);
+      TEST_CHECK(server->num_cookies == 0);
+    }
+  }
+
+  NNS_Finalise();
+  NKS_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/quantiles.c b/test/unit/quantiles.c
new file mode 100644
index 0000000..5d97df6
--- /dev/null
+++ b/test/unit/quantiles.c
@@ -0,0 +1,68 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+ */
+
+#include <local.h>
+#include "test.h"
+
+#include <quantiles.c>
+
+void
+test_unit(void)
+{
+  int i, j, k, min_k, max_k, q, r, in_order, out_order;
+  QNT_Instance inst;
+  double x;
+
+  in_order = out_order = 0;
+
+  for (i = 0; i < 100; i++) {
+    r = random() % 10 + 1;
+    q = random() % 20 + 2;
+    do {
+      min_k = random() % (q - 1) + 1;
+      max_k = random() % (q - 1) + 1;
+    } while (min_k > max_k);
+
+    inst = QNT_CreateInstance(min_k, max_k, q, r, 1e-9);
+
+    TEST_CHECK(min_k == QNT_GetMinK(inst));
+
+    for (j = 0; j < 3000; j++) {
+      x = TST_GetRandomDouble(0.0, 2e-6);
+      QNT_Accumulate(inst, x);
+      for (k = min_k; k < max_k; k++)
+        if (j < max_k - min_k) {
+          TEST_CHECK(QNT_GetQuantile(inst, k) <= QNT_GetQuantile(inst, k + 1));
+        } else if (j > 1000) {
+          if (QNT_GetQuantile(inst, k) <= QNT_GetQuantile(inst, k + 1))
+            in_order++;
+          else
+            out_order++;
+        }
+    }
+
+    QNT_Reset(inst);
+    TEST_CHECK(inst->n_set == 0);
+
+    QNT_DestroyInstance(inst);
+  }
+
+  TEST_CHECK(in_order > 100 * out_order);
+}
diff --git a/test/unit/regress.c b/test/unit/regress.c
new file mode 100644
index 0000000..f47d1c4
--- /dev/null
+++ b/test/unit/regress.c
@@ -0,0 +1,119 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+#include <regress.c>
+#include "test.h"
+
+#define POINTS 64
+
+void
+test_unit(void)
+{
+  double x[POINTS], x2[POINTS], y[POINTS], w[POINTS];
+  double b0, b1, b2, s2, sb0, sb1, slope, slope2, intercept, sd, median;
+  double xrange, yrange, wrange, x2range;
+  int i, j, n, m, c1, c2, c3, runs, best_start, dof;
+
+  for (n = 3; n <= POINTS; n++) {
+    for (i = 0; i < 200; i++) {
+      slope = TST_GetRandomDouble(-0.1, 0.1);
+      intercept = TST_GetRandomDouble(-1.0, 1.0);
+      sd = TST_GetRandomDouble(1e-6, 1e-4);
+      slope2 = (random() % 2 ? 1 : -1) * TST_GetRandomDouble(0.1, 0.5);
+
+      DEBUG_LOG("iteration %d n=%d intercept=%e slope=%e sd=%e",
+                i, n, intercept, slope, sd);
+
+      for (j = 0; j < n; j++) {
+        x[j] = -j;
+        y[j] = intercept + slope * x[j] + (j % 2 ? 1 : -1) * TST_GetRandomDouble(1e-6, sd);
+        w[j] = TST_GetRandomDouble(1.0, 2.0);
+        x2[j] = (y[j] - intercept - slope * x[j]) / slope2;
+      }
+
+      RGR_WeightedRegression(x, y, w, n, &b0, &b1, &s2, &sb0, &sb1);
+      DEBUG_LOG("WR b0=%e b1=%e s2=%e sb0=%e sb1=%e", b0, b1, s2, sb0, sb1);
+      TEST_CHECK(fabs(b0 - intercept) < sd + 1e-3);
+      TEST_CHECK(fabs(b1 - slope) < sd);
+
+      if (RGR_FindBestRegression(x, y, w, n, 0, 3, &b0, &b1, &s2, &sb0, &sb1,
+                                 &best_start, &runs, &dof)) {
+        DEBUG_LOG("BR b0=%e b1=%e s2=%e sb0=%e sb1=%e runs=%d bs=%d dof=%d",
+                  b0, b1, s2, sb0, sb1, runs, best_start, dof);
+
+        TEST_CHECK(fabs(b0 - intercept) < sd + 1e-3);
+        TEST_CHECK(fabs(b1 - slope) < sd);
+      }
+
+      if (RGR_MultipleRegress(x, x2, y, n, &b2)) {
+        DEBUG_LOG("MR b2=%e", b2);
+        TEST_CHECK(fabs(b2 - slope2) < 1e-6);
+      }
+
+      for (j = 0; j < n / 7; j++)
+        y[random() % n] += 100 * sd;
+
+      if (RGR_FindBestRobustRegression(x, y, n, 1e-8, &b0, &b1, &runs, &best_start)) {
+        DEBUG_LOG("BRR b0=%e b1=%e runs=%d bs=%d", b0, b1, runs, best_start);
+
+        TEST_CHECK(fabs(b0 - intercept) < sd + 1e-2);
+        TEST_CHECK(fabs(b1 - slope) < 5.0 * sd);
+      }
+
+      for (j = 0; j < n; j++)
+        x[j] = random() % 4 * TST_GetRandomDouble(-1000, 1000);
+
+      median = RGR_FindMedian(x, n);
+
+      for (j = c1 = c2 = c3 = 0; j < n; j++) {
+        if (x[j] < median)
+          c1++;
+        if (x[j] > median)
+          c3++;
+        else
+          c2++;
+      }
+
+      TEST_CHECK(c1 + c2 >= c3 && c1 <= c2 + c3);
+
+      xrange = TST_GetRandomDouble(1e-6, pow(10.0, random() % 10));
+      yrange = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      wrange = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      x2range = random() % 3 * TST_GetRandomDouble(0.0, pow(10.0, random() % 10));
+      m = random() % n;
+
+      for (j = 0; j < n; j++) {
+        x[j] = (j ? x[j - 1] : 0.0) + TST_GetRandomDouble(1e-6, xrange);
+        y[j] = TST_GetRandomDouble(-yrange, yrange);
+        w[j] = 1.0 + TST_GetRandomDouble(0.0, wrange);
+        x2[j] = TST_GetRandomDouble(-x2range, x2range);
+      }
+
+      RGR_WeightedRegression(x, y, w, n, &b0, &b1, &s2, &sb0, &sb1);
+
+      if (RGR_FindBestRegression(x + m, y + m, w, n - m, m, 3, &b0, &b1, &s2, &sb0, &sb1,
+                                 &best_start, &runs, &dof))
+        ;
+      if (RGR_MultipleRegress(x, x2, y, n, &b2))
+        ;
+      if (RGR_FindBestRobustRegression(x, y, n, 1e-8, &b0, &b1, &runs, &best_start))
+        ;
+    }
+  }
+}
diff --git a/test/unit/samplefilt.c b/test/unit/samplefilt.c
new file mode 100644
index 0000000..19d2f70
--- /dev/null
+++ b/test/unit/samplefilt.c
@@ -0,0 +1,120 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2018
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <local.h>
+#include "test.h"
+
+#define LCL_GetSysPrecisionAsQuantum() (1.0e-6)
+
+#include <samplefilt.c>
+
+void
+test_unit(void)
+{
+  NTP_Sample sample_in, sample_out;
+  SPF_Instance filter;
+  int i, j, k, sum_count, min_samples, max_samples;
+  double mean, combine_ratio, sum_err;
+
+  LCL_Initialise();
+
+  memset(&sample_in, 0, sizeof (sample_in));
+  memset(&sample_out, 0, sizeof (sample_out));
+
+  for (i = 0; i <= 100; i++) {
+    max_samples = random() % 20 + 1;
+    min_samples = random() % (max_samples) + 1;
+    combine_ratio = TST_GetRandomDouble(0.0, 1.0);
+
+    filter = SPF_CreateInstance(min_samples, max_samples, 2.0, combine_ratio);
+
+    TEST_CHECK(max_samples == SPF_GetMaxSamples(filter));
+
+    for (j = 0, sum_count = 0, sum_err = 0.0; j < 100; j++) {
+      DEBUG_LOG("iteration %d/%d", i, j);
+
+      mean = TST_GetRandomDouble(-1.0e3, 1.0e3);
+      UTI_ZeroTimespec(&sample_in.time);
+
+      for (k = 0; k < 100; k++) {
+        UTI_AddDoubleToTimespec(&sample_in.time, TST_GetRandomDouble(1.0e-1, 1.0e2),
+                                &sample_in.time);
+        sample_in.offset = mean + TST_GetRandomDouble(-1.0, 1.0);
+        sample_in.peer_dispersion = TST_GetRandomDouble(1.0e-4, 2.0e-4);
+        sample_in.root_dispersion = TST_GetRandomDouble(1.0e-3, 2.0e-3);
+        sample_in.peer_delay = TST_GetRandomDouble(1.0e-2, 2.0e-2);
+        sample_in.root_delay = TST_GetRandomDouble(1.0e-1, 2.0e-1);
+
+        TEST_CHECK(SPF_AccumulateSample(filter, &sample_in));
+        TEST_CHECK(!SPF_AccumulateSample(filter, &sample_in));
+
+        TEST_CHECK(SPF_GetNumberOfSamples(filter) == MIN(k + 1, max_samples));
+
+        SPF_GetLastSample(filter, &sample_out);
+        TEST_CHECK(!memcmp(&sample_in, &sample_out, sizeof (sample_in)));
+
+        SPF_SlewSamples(filter, &sample_in.time, 0.0, 0.0);
+        SPF_CorrectOffset(filter, 0.0);
+        SPF_AddDispersion(filter, 0.0);
+
+        if (k + 1 < min_samples)
+          TEST_CHECK(!SPF_GetFilteredSample(filter, &sample_out));
+
+        TEST_CHECK(SPF_GetNumberOfSamples(filter) == MIN(k + 1, max_samples));
+      }
+
+      if (random() % 10) {
+        TEST_CHECK(SPF_GetFilteredSample(filter, &sample_out));
+
+        TEST_CHECK(SPF_GetAvgSampleDispersion(filter) <= 2.0);
+
+        sum_err += sample_out.offset - mean;
+        sum_count++;
+
+        TEST_CHECK(UTI_CompareTimespecs(&sample_out.time, &sample_in.time) <= 0 &&
+                   sample_out.time.tv_sec >= 0);
+        TEST_CHECK(fabs(sample_out.offset - mean) <= 1.0);
+        TEST_CHECK(sample_out.peer_dispersion >= 1.0e-4 &&
+                   (sample_out.peer_dispersion <= 2.0e-4 || filter->max_samples > 1));
+        TEST_CHECK(sample_out.root_dispersion >= 1.0e-3 &&
+                   (sample_out.root_dispersion <= 2.0e-3 || filter->max_samples > 1));
+        TEST_CHECK(sample_out.peer_delay >= 1.0e-2 &&
+                   sample_out.peer_delay <= 2.0e-2);
+        TEST_CHECK(sample_out.root_delay >= 1.0e-1 &&
+                   sample_out.root_delay <= 2.0e-1);
+
+        if (max_samples == 1)
+          TEST_CHECK(!memcmp(&sample_in, &sample_out, sizeof (sample_in)));
+
+      } else {
+        SPF_DropSamples(filter);
+        TEST_CHECK(filter->last < 0);
+      }
+
+      TEST_CHECK(SPF_GetNumberOfSamples(filter) == 0);
+    }
+
+    TEST_CHECK(fabs(sum_err / sum_count) < 0.3);
+
+    SPF_DestroyInstance(filter);
+  }
+
+  LCL_Finalise();
+}
diff --git a/test/unit/siv.c b/test/unit/siv.c
new file mode 100644
index 0000000..54f435d
--- /dev/null
+++ b/test/unit/siv.c
@@ -0,0 +1,423 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <logging.h>
+#include <siv.h>
+#include "test.h"
+
+#ifdef HAVE_SIV
+
+struct siv_test {
+  SIV_Algorithm algorithm;
+  const unsigned char key[64];
+  int key_length;
+  const unsigned char nonce[128];
+  int nonce_length;
+  const unsigned char assoc[128];
+  int assoc_length;
+  const unsigned char plaintext[128];
+  int plaintext_length;
+  const unsigned char ciphertext[128];
+  int ciphertext_length;
+};
+
+void
+test_unit(void)
+{
+  struct siv_test tests[] = {
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "", 0,
+      "", 0,
+      "\x22\x3e\xb5\x94\xe0\xe0\x25\x4b\x00\x25\x8e\x21\x9a\x1c\xa4\x21", 16
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "", 0,
+      "\xd7\x20\x19\x89\xc6\xdb\xc6\xd6\x61\xfc\x62\xbc\x86\x5e\xee\xef", 16
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "", 0,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "\xb6\xc1\x60\xe9\xc2\xfd\x2a\xe8\xde\xc5\x36\x8b\x2a\x33\xed\xe1"
+      "\x14\xff\xb3\x97\x34\x5c\xcb\xe4\x4a\xa4\xde\xac\xd9\x36\x90\x46", 32
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e", 15,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c", 15,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4", 15,
+      "\x03\x8c\x41\x51\xba\x7a\x8f\x77\x6e\x56\x31\x99\x42\x0b\xc7\x03"
+      "\xe7\x6c\x67\xc9\xda\xb7\x0d\x5b\x44\x06\x26\x5a\xd0\xd2\x3b", 31
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f", 16,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7", 16,
+      "\x5c\x05\x23\x65\xf4\x57\x0a\xa0\xfb\x38\x3e\xce\x9b\x75\x85\xeb"
+      "\x68\x85\x19\x36\x0c\x7c\x48\x11\x40\xcb\x9b\x57\x9a\x0e\x65\x32", 32
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
+      "\xd5", 17,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b"
+      "\xa0", 17,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7"
+      "\x08", 17,
+      "\xaf\x58\x4b\xe7\x82\x1e\x96\x19\x29\x91\x25\xe0\xdd\x80\x3b\x49"
+      "\xa5\x11\xcd\xb6\x08\xf3\x76\xa0\xb6\xfa\x15\x82\xf3\x95\xe1\xeb"
+      "\xbd", 33
+    },
+    { AEAD_AES_SIV_CMAC_256,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde"
+      "\xef\x01\x23\x45\x67\x89\xab\xcd\xde\xf0\x12\x34\x56\x78\x9a\xbc", 32,
+      "\xb0\x5a\x1b\xc7\x56\xe7\xb6\x2c\xb4\x85\xe5\x56\xa5\x28\xc0\x6c"
+      "\x2f\x3b\x0b\x9d\x1a\x0c\xdf\x69\x47\xe0\xcc\xc0\x87\xaa\x5c\x09"
+      "\x98\x48\x8d\x6a\x8e\x1e\x05\xd7\x8b\x68\x74\x83\xb5\x1d\xf1\x2c", 48,
+      "\xe5\x8b\xd2\x6a\x30\xc5\xc5\x61\xcc\xbd\x7c\x27\xbf\xfe\xf9\x06"
+      "\x00\x5b\xd7\xfc\x11\x0b\xcf\x16\x61\xef\xac\x05\xa7\xaf\xec\x27"
+      "\x41\xc8\x5e\x9e\x0d\xf9\x2f\xaf\x20\x79\x17\xe5\x17\x91\x2a\x27"
+      "\x34\x1c\xbc\xaf\xeb\xef\x7f\x52\xe7\x1e\x4c\x2a\xca\xbd\x2b\xbe"
+      "\x34\xd6\xfb\x69\xd3\x3e\x49\x59\x60\xb4\x26\xc9\xb8\xce\xba", 79,
+      "\x6c\xe7\xcf\x7e\xab\x7b\xa0\xe1\xa7\x22\xcb\x88\xde\x5e\x42\xd2"
+      "\xec\x79\xe0\xa2\xcf\x5f\x0f\x6f\x6b\x89\x57\xcd\xae\x17\xd4\xc2"
+      "\xf3\x1b\xa2\xa8\x13\x78\x23\x2f\x83\xa8\xd4\x0c\xc0\xd2\xf3\x99"
+      "\xae\x81\xa1\xca\x5b\x5f\x45\xa6\x6f\x0c\x8a\xf3\xd4\x67\x40\x81"
+      "\x26\xe2\x01\x86\xe8\x5a\xd5\xf8\x58\x80\x9f\x56\xaa\x76\x96\xbf"
+      "\x31", 81,
+      "\x9a\x06\x33\xe0\xee\x00\x6a\x9b\xc8\x20\xd5\xe2\xc2\xed\xb5\x75"
+      "\xfa\x9e\x42\x2a\x31\x6b\xda\xca\xaa\x7d\x31\x8b\x84\x7a\xb8\xd7"
+      "\x8a\x81\x25\x64\xed\x41\x9b\xa9\x77\x10\xbd\x05\x0c\x4e\xc5\x31"
+      "\x0c\xa2\x86\xec\x8a\x94\xc8\x24\x23\x3c\x13\xee\xa5\x51\xc9\xdf"
+      "\x48\xc9\x55\xc5\x2f\x40\x73\x3f\x98\xbb\x8d\x69\x78\x46\x64\x17"
+      "\x8d\x49\x2f\x14\x62\xa4\x7c\x2a\x57\x38\x87\xce\xc6\x72\xd3\x5c"
+      "\xa1", 97
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "", 0,
+      "", 0,
+      "\xba\x05\x1c\x40\xeb\x7e\x5f\xa2\x3f\x6c\xe5\xbe\xfe\x5b\x04\xad", 16
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "", 0,
+      "\x8f\x47\xfe\x1f\x26\x4e\xe2\x99\x5f\x35\x3d\x26\x74\x14\xd4\x3b", 16
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "", 0,
+      "\xba\x05\x1c\x40\xeb\x7e\x5f\xa2\x3f\x6c\xe5\xbe\xfe\x5b\x04\xad", 16,
+      "\xa1\xc6\x1b\xf7\x32\x39\x93\x0e\x10\xf8\xa6\x21\x6c\x6e\x26\x83"
+      "\x5c\xa9\xb0\xdd\x91\x0f\x81\xa6\xf0\x3b\x45\xda\xa6\x9a\x2b\x24", 32,
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c", 15,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4", 15,
+      "\x7a\x23\xa7\x35\x8d\x34\x5b\xf6\x0d\xa7\x6d\x3b\x58\x8c\x4c\x65"
+      "\xd9\x85\x4e\x17\xb7\x52\x48\xf7\x91\xb4\xdd\xd6\x8b\xec\x02", 31
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b", 16,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7", 16,
+      "\xa3\x10\xae\x5f\x26\xd9\x90\xfa\xab\x30\x29\x80\x7f\x93\x62\x23"
+      "\x83\x8f\xc9\x57\x90\xbb\x05\x87\x02\x11\x57\xd6\x13\x9b\x82\x4d", 32
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b", 12,
+      "\x4c\x9d\x4f\xca\xed\x8a\xe2\xba\xad\x3f\x3e\xa6\xe9\x3c\x8c\x8b"
+      "\xa0", 17,
+      "\xba\x99\x79\x31\x23\x7e\x3c\x53\x58\x7e\xd4\x93\x02\xab\xe4\xa7"
+      "\x08", 17,
+      "\x4c\x48\x67\x48\xce\x8b\x14\x7b\x70\xac\x71\xe8\x7b\x4e\x4a\x6a"
+      "\xb4\x3d\xb5\x8e\x58\x81\xfc\x3e\x97\xcd\xdf\xef\x67\x1e\xf4\x4f"
+      "\x0d", 33
+    },
+    { AEAD_AES_128_GCM_SIV,
+      "\x01\x23\x45\x67\x89\xab\xcd\xef\xf0\x12\x34\x56\x78\x9a\xbc\xde", 16,
+      "\xb0\x5a\x1b\xc7\x56\xe7\xb6\x2c\xb4\x85\xe5\x56", 12,
+      "\xe5\x8b\xd2\x6a\x30\xc5\xc5\x61\xcc\xbd\x7c\x27\xbf\xfe\xf9\x06"
+      "\x00\x5b\xd7\xfc\x11\x0b\xcf\x16\x61\xef\xac\x05\xa7\xaf\xec\x27"
+      "\x41\xc8\x5e\x9e\x0d\xf9\x2f\xaf\x20\x79\x17\xe5\x17\x91\x2a\x27"
+      "\x34\x1c\xbc\xaf\xeb\xef\x7f\x52\xe7\x1e\x4c\x2a\xca\xbd\x2b\xbe"
+      "\x34\xd6\xfb\x69\xd3\x3e\x49\x59\x60\xb4\x26\xc9\xb8\xce\xba", 79,
+      "\x6c\xe7\xcf\x7e\xab\x7b\xa0\xe1\xa7\x22\xcb\x88\xde\x5e\x42\xd2"
+      "\xec\x79\xe0\xa2\xcf\x5f\x0f\x6f\x6b\x89\x57\xcd\xae\x17\xd4\xc2"
+      "\xf3\x1b\xa2\xa8\x13\x78\x23\x2f\x83\xa8\xd4\x0c\xc0\xd2\xf3\x99"
+      "\xae\x81\xa1\xca\x5b\x5f\x45\xa6\x6f\x0c\x8a\xf3\xd4\x67\x40\x81"
+      "\x26\xe2\x01\x86\xe8\x5a\xd5\xf8\x58\x80\x9f\x56\xaa\x76\x96\xbf"
+      "\x31", 81,
+      "\xf6\xa0\x1a\xf3\x4f\xe9\x36\xde\x5c\xbd\xb6\x0a\x26\x9d\x60\x1d"
+      "\xe6\xc9\x6d\xb8\xf2\x5f\xcd\xce\x26\xf4\x0d\x86\xec\xdd\x84\x25"
+      "\xaf\xec\x72\x10\x2d\x74\x2d\xde\x95\x84\xac\xce\xbf\x8a\x52\x9f"
+      "\x10\x6f\xc2\xa8\x1f\xed\x47\xff\xeb\x28\x57\x54\xb3\x45\x45\x56"
+      "\xbb\xcf\x7d\x9b\x99\x68\xbd\x36\x75\xe3\xf7\x8c\x09\x25\x01\xbe"
+      "\xe1\xe2\x3d\x19\x4f\x15\x64\x12\x6e\xea\x67\x6c\x42\x2f\xc1\x91"
+      "\xff", 97
+    },
+    { 0, "", 0 }
+  };
+
+  unsigned char plaintext[sizeof (((struct siv_test *)NULL)->plaintext)];
+  unsigned char ciphertext[sizeof (((struct siv_test *)NULL)->ciphertext)];
+  SIV_Instance siv;
+  int i, j, r, fixed_nonce_length;
+
+  for (i = 0; i < AEAD_AES_256_GCM_SIV + 10; i++) {
+    switch (i) {
+      case AEAD_AES_SIV_CMAC_256:
+      case AEAD_AES_128_GCM_SIV:
+        continue;
+    }
+    TEST_CHECK(SIV_GetKeyLength(i) == 0);
+    TEST_CHECK(SIV_CreateInstance(i) == NULL);
+  }
+
+  for (i = 0; tests[i].algorithm != 0; i++) {
+    DEBUG_LOG("testing %d (%d)", (int)tests[i].algorithm, i);
+
+    assert(tests[i].key_length <= sizeof (tests[i].key));
+    assert(tests[i].nonce_length <= sizeof (tests[i].nonce));
+    assert(tests[i].assoc_length <= sizeof (tests[i].assoc));
+    assert(tests[i].plaintext_length <= sizeof (tests[i].plaintext));
+    assert(tests[i].ciphertext_length <= sizeof (tests[i].ciphertext));
+
+    siv = SIV_CreateInstance(tests[i].algorithm);
+
+    switch (tests[i].algorithm) {
+      case AEAD_AES_SIV_CMAC_256:
+        TEST_CHECK(siv != NULL);
+        fixed_nonce_length = 0;
+        break;
+      case AEAD_AES_128_GCM_SIV:
+        fixed_nonce_length = 1;
+        break;
+      default:
+        assert(0);
+    }
+
+    if (!siv) {
+      DEBUG_LOG("missing %d support", (int)tests[i].algorithm);
+      TEST_CHECK(SIV_GetKeyLength(tests[i].algorithm) == 0);
+      continue;
+    }
+
+    TEST_CHECK(SIV_GetKeyLength(tests[i].algorithm) == tests[i].key_length);
+    TEST_CHECK(SIV_GetMinNonceLength(siv) >= 1);
+    TEST_CHECK(SIV_GetMinNonceLength(siv) <= 12);
+    TEST_CHECK(SIV_GetMaxNonceLength(siv) >= 12);
+    TEST_CHECK(SIV_GetMinNonceLength(siv) <= SIV_GetMaxNonceLength(siv));
+    if (fixed_nonce_length)
+      TEST_CHECK(SIV_GetMinNonceLength(siv) == SIV_GetMaxNonceLength(siv));
+
+    r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].plaintext, tests[i].plaintext_length,
+                    ciphertext, tests[i].ciphertext_length);
+    TEST_CHECK(!r);
+    r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].ciphertext, tests[i].ciphertext_length,
+                    plaintext, tests[i].plaintext_length);
+    TEST_CHECK(!r);
+
+    for (j = -1; j < 1024; j++) {
+      r = SIV_SetKey(siv, tests[i].key, j);
+      TEST_CHECK(r == (j == tests[i].key_length));
+    }
+
+    TEST_CHECK(SIV_GetTagLength(siv) == tests[i].ciphertext_length - tests[i].plaintext_length);
+
+    r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].plaintext, tests[i].plaintext_length,
+                    ciphertext, tests[i].ciphertext_length);
+    TEST_CHECK(r);
+
+#if 0
+    for (j = 0; j < tests[i].ciphertext_length; j++) {
+      printf("\\x%02x", ciphertext[j]);
+      if (j % 16 == 15)
+        printf("\n");
+    }
+    printf("\n");
+#endif
+    TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) == 0);
+
+    for (j = -1; j < tests[i].nonce_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, j,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, tests[i].ciphertext_length);
+      if (j > 0 && (j == tests[i].nonce_length || !fixed_nonce_length)) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < tests[i].assoc_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, j,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, tests[i].ciphertext_length);
+      if (j >= 0) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, tests[i].ciphertext_length) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < tests[i].plaintext_length; j++) {
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, j,
+                      ciphertext, j + SIV_GetTagLength(siv));
+      if (j >= 0) {
+        TEST_CHECK(r);
+        TEST_CHECK(memcmp(ciphertext, tests[i].ciphertext, j + SIV_GetTagLength(siv)) != 0);
+      } else {
+        TEST_CHECK(!r);
+      }
+    }
+
+    for (j = -1; j < 2 * tests[i].plaintext_length; j++) {
+      if (j == tests[i].plaintext_length)
+        continue;
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, j,
+                      ciphertext, tests[i].ciphertext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < 2 * tests[i].ciphertext_length; j++) {
+      if (j == tests[i].ciphertext_length)
+        continue;
+      r = SIV_Encrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].plaintext, tests[i].plaintext_length,
+                      ciphertext, j);
+      TEST_CHECK(!r);
+    }
+
+    r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                    tests[i].assoc, tests[i].assoc_length,
+                    tests[i].ciphertext, tests[i].ciphertext_length,
+                    plaintext, tests[i].plaintext_length);
+    TEST_CHECK(r);
+    TEST_CHECK(memcmp(plaintext, tests[i].plaintext, tests[i].plaintext_length) == 0);
+
+    for (j = -1; j < tests[i].nonce_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, j,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < tests[i].assoc_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, j,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < 2 * tests[i].ciphertext_length; j++) {
+      if (j == tests[i].ciphertext_length)
+        continue;
+
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, j,
+                      plaintext, tests[i].plaintext_length);
+      TEST_CHECK(!r);
+    }
+
+    for (j = -1; j < tests[i].plaintext_length; j++) {
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, tests[i].ciphertext_length,
+                      plaintext, j);
+      TEST_CHECK(!r);
+
+      r = SIV_Decrypt(siv, tests[i].nonce, tests[i].nonce_length,
+                      tests[i].assoc, tests[i].assoc_length,
+                      tests[i].ciphertext, j + SIV_GetTagLength(siv),
+                      plaintext, j);
+      TEST_CHECK(!r);
+    }
+
+    SIV_DestroyInstance(siv);
+  }
+
+  siv = SIV_CreateInstance(tests[0].algorithm);
+  for (i = 0; i < 1000; i++) {
+    for (j = 0; tests[j].algorithm == tests[0].algorithm; j++) {
+      r = SIV_SetKey(siv, tests[j].key, tests[j].key_length);
+      TEST_CHECK(r);
+      r = SIV_Encrypt(siv, tests[j].nonce, tests[j].nonce_length,
+                      tests[j].assoc, tests[j].assoc_length,
+                      tests[j].plaintext, tests[j].plaintext_length,
+                      ciphertext, tests[j].ciphertext_length);
+      TEST_CHECK(r);
+      r = SIV_Decrypt(siv, tests[j].nonce, tests[j].nonce_length,
+                      tests[j].assoc, tests[j].assoc_length,
+                      tests[j].ciphertext, tests[j].ciphertext_length,
+                      plaintext, tests[j].plaintext_length);
+      TEST_CHECK(r);
+    }
+  }
+  SIV_DestroyInstance(siv);
+}
+#else
+void
+test_unit(void)
+{
+  TEST_REQUIRE(0);
+}
+#endif
diff --git a/test/unit/smooth.c b/test/unit/smooth.c
new file mode 100644
index 0000000..998a4d1
--- /dev/null
+++ b/test/unit/smooth.c
@@ -0,0 +1,63 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <smooth.c>
+#include "test.h"
+
+void
+test_unit(void)
+{
+  int i, j;
+  struct timespec ts;
+  double offset, freq, wander;
+  char conf[] = "smoothtime 300 0.01";
+
+  CNF_Initialise(0, 0);
+  CNF_ParseLine(NULL, 1, conf);
+
+  LCL_Initialise();
+  SMT_Initialise();
+  locked = 0;
+
+  for (i = 0; i < 500; i++) {
+    UTI_ZeroTimespec(&ts);
+    SMT_Reset(&ts);
+
+    DEBUG_LOG("iteration %d", i);
+
+    offset = (random() % 1000000 - 500000) / 1.0e6;
+    freq = (random() % 1000000 - 500000) / 1.0e9;
+    update_smoothing(&ts, offset, freq);
+
+    for (j = 0; j < 10000; j++) {
+      update_smoothing(&ts, 0.0, 0.0);
+      UTI_AddDoubleToTimespec(&ts, 16.0, &ts);
+      get_smoothing(&ts, &offset, &freq, &wander);
+    }
+
+    TEST_CHECK(fabs(offset) < 1e-12);
+    TEST_CHECK(fabs(freq) < 1e-12);
+    TEST_CHECK(fabs(wander) < 1e-12);
+  }
+
+  SMT_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+}
diff --git a/test/unit/sources.c b/test/unit/sources.c
new file mode 100644
index 0000000..155e819
--- /dev/null
+++ b/test/unit/sources.c
@@ -0,0 +1,289 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016, 2018, 2022
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <sources.c>
+#include "test.h"
+
+static SRC_Instance
+create_source(SRC_Type type, IPAddr *addr, int authenticated, int sel_options)
+{
+  TST_GetRandomAddress(addr, IPADDR_UNSPEC, -1);
+
+  return SRC_CreateNewInstance(UTI_IPToRefid(addr), type, authenticated, sel_options,
+                               type == SRC_NTP ? addr : NULL,
+                               SRC_DEFAULT_MINSAMPLES, SRC_DEFAULT_MAXSAMPLES, 0.0, 1.0);
+}
+
+void
+test_unit(void)
+{
+  SRC_AuthSelectMode sel_mode;
+  SRC_Instance srcs[16];
+  IPAddr addrs[16];
+  RPT_SourceReport report;
+  NTP_Sample sample;
+  int i, j, k, l, n1, n2, n3, n4, samples, sel_options;
+  char conf[128];
+
+  CNF_Initialise(0, 0);
+  LCL_Initialise();
+  TST_RegisterDummyDrivers();
+  SCH_Initialise();
+  SRC_Initialise();
+  REF_Initialise();
+  NSR_Initialise();
+
+  REF_SetMode(REF_ModeIgnore);
+
+  for (i = 0; i < 1000; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      TEST_CHECK(n_sources == j);
+
+      sel_options = i & random() & (SRC_SELECT_NOSELECT | SRC_SELECT_PREFER |
+                                    SRC_SELECT_TRUST | SRC_SELECT_REQUIRE);
+
+      DEBUG_LOG("added source %d options %d", j, sel_options);
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, sel_options);
+      SRC_UpdateReachability(srcs[j], 1);
+
+      samples = (i + j) % 5 + 3;
+
+      sample.offset = TST_GetRandomDouble(-1.0, 1.0);
+
+      for (k = 0; k < samples; k++) {
+        SCH_GetLastEventTime(&sample.time, NULL, NULL);
+        UTI_AddDoubleToTimespec(&sample.time, TST_GetRandomDouble(k - samples, k - samples + 1),
+                                &sample.time);
+
+        sample.offset += TST_GetRandomDouble(-1.0e-2, 1.0e-2);
+        sample.peer_delay = TST_GetRandomDouble(1.0e-6, 1.0e-1);
+        sample.peer_dispersion = TST_GetRandomDouble(1.0e-6, 1.0e-1);
+        sample.root_delay = sample.peer_delay;
+        sample.root_dispersion = sample.peer_dispersion;
+
+        if (random() % 2)
+          SRC_UpdateStatus(srcs[j], 1, random() % 4);
+
+        DEBUG_LOG("source %d sample %d offset %f delay %f disp %f", j, k,
+                  sample.offset, sample.peer_delay, sample.peer_dispersion);
+
+        SRC_AccumulateSample(srcs[j], &sample);
+      }
+
+      for (k = 0; k <= j; k++) {
+        int passed = 0, trusted = 0, trusted_passed = 0, required = 0, required_passed = 0;
+        double trusted_lo = DBL_MAX, trusted_hi = DBL_MIN;
+        double passed_lo = DBL_MAX, passed_hi = DBL_MIN;
+
+        SRC_SelectSource(srcs[k]);
+        DEBUG_LOG("source %d status %c", k, get_status_char(sources[k]->status));
+
+        for (l = 0; l <= j; l++) {
+          TEST_CHECK(sources[l]->status > SRC_OK && sources[l]->status <= SRC_SELECTED);
+          if (sources[l]->sel_options & SRC_SELECT_NOSELECT) {
+            TEST_CHECK(sources[l]->status == SRC_UNSELECTABLE);
+          } else if (sources[l]->leap == LEAP_Unsynchronised) {
+            TEST_CHECK(sources[l]->status == SRC_UNSYNCHRONISED);
+          } else if (sources[l]->status != SRC_BAD_DISTANCE) {
+            if (sources[l]->status >= SRC_NONPREFERRED) {
+              passed++;
+              if (passed_lo > sources[l]->sel_info.lo_limit)
+                passed_lo = sources[l]->sel_info.lo_limit;
+              if (passed_hi < sources[l]->sel_info.hi_limit)
+                passed_hi = sources[l]->sel_info.hi_limit;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_TRUST) {
+              trusted++;
+              if (trusted_lo > sources[l]->sel_info.lo_limit)
+                trusted_lo = sources[l]->sel_info.lo_limit;
+              if (trusted_hi < sources[l]->sel_info.hi_limit)
+                trusted_hi = sources[l]->sel_info.hi_limit;
+              if (sources[l]->status >= SRC_NONPREFERRED)
+                trusted_passed++;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_REQUIRE) {
+              required++;
+              if (sources[l]->status >= SRC_NONPREFERRED)
+                required_passed++;
+            }
+            if (sources[l]->sel_options & SRC_SELECT_PREFER)
+              TEST_CHECK(sources[l]->status != SRC_NONPREFERRED);
+          }
+        }
+
+        DEBUG_LOG("sources %d passed %d trusted %d/%d required %d/%d", j + 1, passed,
+                  trusted_passed, trusted, required_passed, required);
+
+        TEST_CHECK(!trusted || !passed || (passed_lo >= trusted_lo && passed_hi <= trusted_hi));
+        TEST_CHECK(!passed || !trusted || trusted_passed >= 1);
+        TEST_CHECK(!passed || !required || required_passed > 0);
+
+        for (l = 0; l <= j; l++) {
+          TEST_CHECK(sources[l]->leap_vote ==
+                     (sources[l]->status >= SRC_NONPREFERRED &&
+                      (!trusted || sources[l]->sel_options & SRC_SELECT_TRUST)));
+        }
+      }
+    }
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      SRC_ReportSource(j, &report, &sample.time);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  for (i = 0; i < 16; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      TEST_CHECK(n_sources == j);
+
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, 0);
+      SRC_UpdateReachability(srcs[j], 1);
+
+      samples = 8;
+      for (k = 0; k < samples; k++) {
+        SCH_GetLastEventTime(&sample.time, NULL, NULL);
+        UTI_AddDoubleToTimespec(&sample.time, k - samples, &sample.time);
+        if (j != 0)
+          UTI_AddDoubleToTimespec(&sample.time, -i * (1.0e-3 / LCL_GetMaxClockError()), &sample.time);
+
+        sample.offset = (k % 2) * 1e-8;
+        sample.peer_delay = sample.root_delay = 2.0e-3 * (j + 1);
+        sample.peer_dispersion = sample.root_dispersion = 4.0e-3;
+
+        SRC_AccumulateSample(srcs[j], &sample);
+        SRC_UpdateStatus(srcs[j], 1, LEAP_Normal);
+      }
+    }
+
+    SRC_SelectSource(srcs[0]);
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      DEBUG_LOG("%d %c %f", j, get_status_char(srcs[j]->status),
+                srcs[j]->sel_info.root_distance);
+      if (j == 0)
+        TEST_CHECK(sources[j]->status == SRC_SELECTED);
+      else if (j < 11 - i)
+        TEST_CHECK(sources[j]->status == SRC_UNSELECTED);
+      else
+        TEST_CHECK(sources[j]->status == SRC_DISTANT);
+    }
+
+    for (j = 0; j < sizeof (srcs) / sizeof (srcs[0]); j++) {
+      SCH_GetLastEventTime(&sample.time, NULL, NULL);
+      SRC_ReportSource(j, &report, &sample.time);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  TEST_CHECK(CNF_GetAuthSelectMode() == SRC_AUTHSELECT_MIX);
+
+  for (i = 0; i < 1000; i++) {
+    DEBUG_LOG("iteration %d", i);
+
+    switch (i % 4) {
+      case 0:
+        snprintf(conf, sizeof (conf), "authselectmode require");
+        sel_mode = SRC_AUTHSELECT_REQUIRE;
+        break;
+      case 1:
+        snprintf(conf, sizeof (conf), "authselectmode prefer");
+        sel_mode = SRC_AUTHSELECT_PREFER;
+        break;
+      case 2:
+        snprintf(conf, sizeof (conf), "authselectmode mix");
+        sel_mode = SRC_AUTHSELECT_MIX;
+        break;
+      case 3:
+        snprintf(conf, sizeof (conf), "authselectmode ignore");
+        sel_mode = SRC_AUTHSELECT_IGNORE;
+        break;
+    }
+
+    CNF_ParseLine(NULL, 0, conf);
+    TEST_CHECK(CNF_GetAuthSelectMode() == sel_mode);
+
+    sel_options = random() & (SRC_SELECT_PREFER | SRC_SELECT_TRUST | SRC_SELECT_REQUIRE);
+
+    n1 = random() % 3;
+    n2 = random() % 3;
+    n3 = random() % 3;
+    n4 = random() % 3;
+    assert(n1 + n2 + n3 < sizeof (srcs) / sizeof (srcs[0]));
+
+    for (j = 0; j < n1; j++)
+      srcs[j] = create_source(SRC_REFCLOCK, &addrs[j], random() % 2, sel_options);
+    for (; j < n1 + n2; j++)
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 1, sel_options);
+    for (; j < n1 + n2 + n3; j++)
+      srcs[j] = create_source(SRC_NTP, &addrs[j], 0, sel_options);
+    for (; j < n1 + n2 + n3 + n4; j++)
+      srcs[j] = create_source(random() % 2 ? SRC_REFCLOCK : SRC_NTP, &addrs[j],
+                              random() % 2, sel_options | SRC_SELECT_NOSELECT);
+
+    switch (sel_mode) {
+      case SRC_AUTHSELECT_IGNORE:
+        for (j = 0; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        break;
+      case SRC_AUTHSELECT_MIX:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options ==
+                     (sel_options | (n2 > 0 && n3 > 0 ? SRC_SELECT_REQUIRE | SRC_SELECT_TRUST : 0)));
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        break;
+      case SRC_AUTHSELECT_PREFER:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == (sel_options | (n2 > 0 ? SRC_SELECT_NOSELECT : 0)));
+        break;
+      case SRC_AUTHSELECT_REQUIRE:
+        for (j = 0; j < n1 + n2; j++)
+          TEST_CHECK(srcs[j]->sel_options == sel_options);
+        for (; j < n1 + n2 + n3; j++)
+          TEST_CHECK(srcs[j]->sel_options == (sel_options | SRC_SELECT_NOSELECT));
+        break;
+      default:
+        assert(0);
+    }
+
+    for (j = n1 + n2 + n3; j < n1 + n2 + n3 + n4; j++)
+      TEST_CHECK(srcs[j]->sel_options == (sel_options | SRC_SELECT_NOSELECT));
+
+    for (j = n1 + n2 + n3 + n4 - 1; j >= 0; j--) {
+      if (j < n1 + n2)
+        TEST_CHECK(srcs[j]->sel_options == sel_options);
+      SRC_DestroyInstance(srcs[j]);
+    }
+  }
+
+  NSR_Finalise();
+  REF_Finalise();
+  SRC_Finalise();
+  SCH_Finalise();
+  LCL_Finalise();
+  CNF_Finalise();
+  HSH_Finalise();
+}
diff --git a/test/unit/test.c b/test/unit/test.c
new file mode 100644
index 0000000..1ebb11a
--- /dev/null
+++ b/test/unit/test.c
@@ -0,0 +1,182 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <config.h>
+#include <sysincl.h>
+#include <logging.h>
+#include <localp.h>
+#include <util.h>
+
+#include "test.h"
+
+void
+TST_Fail(int line)
+{
+  printf("FAIL (on line %d)\n", line);
+  exit(1);
+}
+
+void
+TST_Skip(int line)
+{
+  printf("SKIP (on line %d)\n", line);
+  exit(0);
+}
+
+int
+main(int argc, char **argv)
+{
+  LOG_Severity log_severity;
+  char *test_name, *s;
+  int i, seed = 0;
+  struct timeval tv;
+
+  test_name = argv[0];
+  s = strrchr(test_name, '.');
+  if (s)
+    *s = '\0';
+  s = strrchr(test_name, '/');
+  if (s)
+    test_name = s + 1;
+
+  log_severity = LOGS_FATAL;
+
+  for (i = 1; i < argc; i++) {
+    if (!strcmp(argv[i], "-d")) {
+      log_severity = LOGS_DEBUG;
+    } else if (!strcmp(argv[i], "-s") && i + 1 < argc) {
+      seed = atoi(argv[++i]);
+    } else {
+      fprintf(stderr, "Unknown option\n");
+      exit(1);
+    }
+  }
+
+  gettimeofday(&tv, NULL);
+  srandom(seed ? seed : tv.tv_sec ^ (tv.tv_usec << 10));
+
+  printf("Testing %-30s ", test_name);
+  fflush(stdout);
+
+  LOG_Initialise();
+  LOG_SetMinSeverity(log_severity);
+
+  test_unit();
+
+  UTI_ResetGetRandomFunctions();
+  LOG_Finalise();
+
+  printf("PASS\n");
+
+  return 0;
+}
+
+double
+TST_GetRandomDouble(double min, double max)
+{
+  return min + random() / 2147483647.0 * (max - min);
+}
+
+void
+TST_GetRandomAddress(IPAddr *ip, int family, int bits)
+{
+  if (family != IPADDR_INET4 && family != IPADDR_INET6)
+    family = random() % 2 ? IPADDR_INET4 : IPADDR_INET6;
+
+  ip->family = family;
+
+  if (family == IPADDR_INET4) {
+    if (bits < 0)
+      bits = 32;
+    assert(bits <= 32);
+
+    if (bits > 16)
+      ip->addr.in4 = (uint32_t)random() % (1U << (bits - 16)) << 16 |
+                     (uint32_t)random() % (1U << 16);
+    else
+      ip->addr.in4 = (uint32_t)random() % (1U << bits);
+  } else {
+    int i, b;
+
+    if (bits < 0)
+      bits = 128;
+    assert(bits <= 128);
+
+    for (i = 0, b = 120; i < 16; i++, b -= 8) {
+      if (b >= bits) {
+        ip->addr.in6[i] = 0;
+      } else {
+        ip->addr.in6[i] = random() % (1U << MIN(bits - b, 8));
+      }
+    }
+  }
+}
+
+void
+TST_SwapAddressBit(IPAddr *ip, unsigned int b)
+{
+  if (ip->family == IPADDR_INET4) {
+    assert(b < 32);
+    ip->addr.in4 ^= 1U << (31 - b);
+  } else if (ip->family == IPADDR_INET6) {
+    assert(b < 128);
+    ip->addr.in6[b / 8] ^= 1U << (7 - b % 8);
+  } else {
+    assert(0);
+  }
+}
+
+static double
+read_frequency(void)
+{
+  return 0.0;
+}
+
+static double
+set_frequency(double freq_ppm)
+{
+  return 0.0;
+}
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+}
+
+static int
+apply_step_offset(double offset)
+{
+  return 0;
+}
+
+static void
+offset_convert(struct timespec *raw, double *corr, double *err)
+{
+  *corr = 0.0;
+  if (err)
+    *err = 0.0;
+}
+
+void
+TST_RegisterDummyDrivers(void)
+{
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency, accrue_offset,
+                            apply_step_offset, offset_convert, NULL, NULL);
+}
diff --git a/test/unit/test.h b/test/unit/test.h
new file mode 100644
index 0000000..00d261d
--- /dev/null
+++ b/test/unit/test.h
@@ -0,0 +1,52 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2016
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#ifndef GOT_TEST_H
+#define GOT_TEST_H
+
+#include <addressing.h>
+
+extern void test_unit(void);
+
+#define TEST_CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      TST_Fail(__LINE__); \
+      exit(1); \
+    } \
+  } while (0)
+
+#define TEST_REQUIRE(expr) \
+  do { \
+    if (!(expr)) { \
+      TST_Skip(__LINE__); \
+      exit(0); \
+    } \
+  } while (0)
+
+extern void TST_Fail(int line);
+extern void TST_Skip(int line);
+
+extern double TST_GetRandomDouble(double min, double max);
+extern void TST_GetRandomAddress(IPAddr *ip, int family, int bits);
+extern void TST_SwapAddressBit(IPAddr *ip, unsigned int b);
+extern void TST_RegisterDummyDrivers(void);
+
+#endif
diff --git a/test/unit/util.c b/test/unit/util.c
new file mode 100644
index 0000000..fa294c4
--- /dev/null
+++ b/test/unit/util.c
@@ -0,0 +1,760 @@
+/*
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2017-2018, 2021
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+ */
+
+#include <util.c>
+#include "test.h"
+
+static volatile int handled_signal = 0;
+
+static void
+handle_signal(int signal)
+{
+  handled_signal = signal;
+}
+
+void
+test_unit(void)
+{
+  struct timespec ts, ts2, ts3, ts4;
+  char buf[16], *s, *s2, *words[3];
+  NTP_int64 ntp_ts, ntp_ts2, ntp_fuzz;
+  NTP_int32 ntp32_ts;
+  struct timeval tv;
+  double x, y, nan, inf;
+  IPAddr ip, ip2, ip3;
+  IPSockAddr ip_saddr;
+  Integer64 integer64;
+  Timespec tspec;
+  Float f;
+  int i, j, c;
+  uid_t uid;
+  gid_t gid;
+  struct stat st;
+  FILE *file;
+
+  for (i = -31; i < 31; i++) {
+    x = pow(2.0, i);
+    y = UTI_Log2ToDouble(i);
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+  }
+
+  for (i = -89; i < 63; i++) {
+    x = pow(2.0, i);
+    y = UTI_FloatNetworkToHost(UTI_FloatHostToNetwork(x));
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+  }
+
+  for (i = 0; i < 100000; i++) {
+    x = TST_GetRandomDouble(-1000.0, 1000.0);
+    y = UTI_FloatNetworkToHost(UTI_FloatHostToNetwork(x));
+    TEST_CHECK(y / x > 0.99999 && y / x < 1.00001);
+
+    UTI_GetRandomBytes(&f, sizeof (f));
+    x = UTI_FloatNetworkToHost(f);
+    TEST_CHECK(x > 0.0 || x <= 0.0);
+  }
+
+  TEST_CHECK(UTI_DoubleToNtp32(1.0) == htonl(65536));
+  TEST_CHECK(UTI_DoubleToNtp32(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(1.0 / (65536.0)) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32(1.000001 / (65536.0)) == htonl(2));
+  TEST_CHECK(UTI_DoubleToNtp32(1.000001) == htonl(65537));
+  TEST_CHECK(UTI_DoubleToNtp32(1000000) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32(-1.0) == htonl(0));
+
+  UTI_DoubleToTimeval(0.4e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 0);
+  UTI_DoubleToTimeval(-0.4e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 0);
+  UTI_DoubleToTimeval(0.5e-6, &tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 1);
+  UTI_DoubleToTimeval(-0.5e-6, &tv);
+  TEST_CHECK(tv.tv_sec == -1);
+  TEST_CHECK(tv.tv_usec == 999999);
+
+  UTI_DoubleToTimespec(0.9e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  UTI_DoubleToTimespec(1.0e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 1);
+  UTI_DoubleToTimespec(-0.9e-9, &ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  UTI_DoubleToTimespec(-1.0e-9, &ts);
+  TEST_CHECK(ts.tv_sec == -1);
+  TEST_CHECK(ts.tv_nsec == 999999999);
+
+  ntp_ts.hi = htonl(JAN_1970);
+  ntp_ts.lo = 0xffffffff;
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+#if defined(HAVE_LONG_TIME_T) && NTP_ERA_SPLIT > 0
+  TEST_CHECK(ts.tv_sec == 0x100000000LL * (1 + (NTP_ERA_SPLIT - 1) / 0x100000000LL));
+#else
+  TEST_CHECK(ts.tv_sec == 0);
+#endif
+  TEST_CHECK(ts.tv_nsec == 999999999);
+
+  ntp_ts.hi = htonl(JAN_1970 - 1);
+  ntp_ts.lo = htonl(0xffffffff);
+  ntp_ts2.hi = htonl(JAN_1970 + 1);
+  ntp_ts2.lo = htonl(0x80000000);
+  TEST_CHECK(fabs(UTI_DiffNtp64ToDouble(&ntp_ts, &ntp_ts2) + 1.5) < 1e-9);
+  TEST_CHECK(fabs(UTI_DiffNtp64ToDouble(&ntp_ts2, &ntp_ts) - 1.5) < 1e-9);
+
+  UTI_AddDoubleToTimespec(&ts, 1e-9, &ts);
+#if defined(HAVE_LONG_TIME_T) && NTP_ERA_SPLIT > 0
+  TEST_CHECK(ts.tv_sec == 1 + 0x100000000LL * (1 + (NTP_ERA_SPLIT - 1) / 0x100000000LL));
+#else
+  TEST_CHECK(ts.tv_sec == 1);
+#endif
+  TEST_CHECK(ts.tv_nsec == 0);
+
+  ntp_fuzz.hi = 0;
+  ntp_fuzz.lo = htonl(0xff1234ff);
+
+  UTI_TimespecToNtp64(&ts, &ntp_ts, &ntp_fuzz);
+  TEST_CHECK(ntp_ts.hi == htonl(JAN_1970 + 1));
+  TEST_CHECK(ntp_ts.lo == ntp_fuzz.lo);
+
+  ts.tv_sec = ts.tv_nsec = 1;
+  UTI_ZeroTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 0);
+  TEST_CHECK(UTI_IsZeroTimespec(&ts));
+
+  ntp_ts.hi = ntp_ts.lo == 1;
+  UTI_ZeroNtp64(&ntp_ts);
+  TEST_CHECK(ntp_ts.hi == 0);
+  TEST_CHECK(ntp_ts.lo == 0);
+
+  tv.tv_sec = tv.tv_usec = 1;
+  UTI_TimevalToTimespec(&tv, &ts);
+  TEST_CHECK(ts.tv_sec == 1);
+  TEST_CHECK(ts.tv_nsec == 1000);
+
+  UTI_TimespecToTimeval(&ts, &tv);
+  TEST_CHECK(tv.tv_sec == 1);
+  TEST_CHECK(tv.tv_usec == 1);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 500000000;
+  TEST_CHECK(fabs(UTI_TimespecToDouble(&ts) - 1.5) < 1.0e-15);
+
+  UTI_DoubleToTimespec(2.75, &ts);
+  TEST_CHECK(ts.tv_sec == 2);
+  TEST_CHECK(ts.tv_nsec == 750000000);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 1200000000;
+  UTI_NormaliseTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 2);
+  TEST_CHECK(ts.tv_nsec == 200000000);
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = -200000000;
+  UTI_NormaliseTimespec(&ts);
+  TEST_CHECK(ts.tv_sec == 0);
+  TEST_CHECK(ts.tv_nsec == 800000000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = 500000;
+  TEST_CHECK(fabs(UTI_TimevalToDouble(&tv) - 1.5) < 1.0e-15);
+
+  UTI_DoubleToTimeval(2.75, &tv);
+  TEST_CHECK(tv.tv_sec == 2);
+  TEST_CHECK(tv.tv_usec == 750000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = 1200000;
+  UTI_NormaliseTimeval(&tv);
+  TEST_CHECK(tv.tv_sec == 2);
+  TEST_CHECK(tv.tv_usec == 200000);
+
+  tv.tv_sec = 1;
+  tv.tv_usec = -200000;
+  UTI_NormaliseTimeval(&tv);
+  TEST_CHECK(tv.tv_sec == 0);
+  TEST_CHECK(tv.tv_usec == 800000);
+
+  UTI_ZeroTimespec(&ts);
+  UTI_TimespecToNtp64(&ts, &ntp_ts, &ntp_fuzz);
+  TEST_CHECK(ntp_ts.hi == 0);
+  TEST_CHECK(ntp_ts.lo == 0);
+
+  TEST_CHECK(UTI_IsZeroNtp64(&ntp_ts));
+
+  ts.tv_sec = 1;
+  ntp_ts.hi = htonl(1);
+
+  TEST_CHECK(!UTI_IsZeroTimespec(&ts));
+  TEST_CHECK(!UTI_IsZeroNtp64(&ntp_ts));
+
+  ts.tv_sec = 0;
+  ntp_ts.hi = 0;
+  ts.tv_nsec = 1;
+  ntp_ts.lo = htonl(1);
+
+  TEST_CHECK(!UTI_IsZeroTimespec(&ts));
+  TEST_CHECK(!UTI_IsZeroNtp64(&ntp_ts));
+
+  ntp_ts.hi = 0;
+  ntp_ts.lo = 0;
+
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+  TEST_CHECK(UTI_IsZeroTimespec(&ts));
+  UTI_TimespecToNtp64(&ts, &ntp_ts, NULL);
+  TEST_CHECK(UTI_IsZeroNtp64(&ntp_ts));
+
+  ntp_fuzz.hi = htonl(1);
+  ntp_fuzz.lo = htonl(3);
+  ntp_ts.hi = htonl(1);
+  ntp_ts.lo = htonl(2);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  ntp_ts.hi = htonl(0x80000002);
+  ntp_ts.lo = htonl(2);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  ntp_fuzz.hi = htonl(0x90000001);
+
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_ts) == 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_ts, &ntp_fuzz) < 0);
+  TEST_CHECK(UTI_CompareNtp64(&ntp_fuzz, &ntp_ts) > 0);
+
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, &ntp_ts, NULL, NULL));
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, NULL, &ntp_ts, NULL));
+  TEST_CHECK(UTI_IsEqualAnyNtp64(&ntp_ts, NULL, NULL, &ntp_ts));
+  TEST_CHECK(!UTI_IsEqualAnyNtp64(&ntp_ts, &ntp_fuzz, &ntp_fuzz, &ntp_fuzz));
+
+  ts.tv_sec = 1;
+  ts.tv_nsec = 2;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 3;
+
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts) == 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) < 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts2, &ts) > 0);
+
+  ts2.tv_sec = 2;
+
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts) == 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) < 0);
+  TEST_CHECK(UTI_CompareTimespecs(&ts2, &ts) > 0);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  UTI_DiffTimespecs(&ts3, &ts, &ts2);
+  TEST_CHECK(ts3.tv_sec == 0);
+  TEST_CHECK(ts3.tv_nsec == 500000000);
+  TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - 0.5) < 1.0e-15);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  ts2.tv_sec = 3;
+  ts2.tv_nsec = 750000000;
+  UTI_DiffTimespecs(&ts3, &ts, &ts2);
+  TEST_CHECK(ts3.tv_sec == -2);
+  TEST_CHECK(ts3.tv_nsec == 500000000);
+  TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - -1.5) < 1.0e-15);
+
+  ts.tv_sec = 2;
+  ts.tv_nsec = 250000000;
+  UTI_AddDoubleToTimespec(&ts, 2.5, &ts2);
+  TEST_CHECK(ts2.tv_sec == 4);
+  TEST_CHECK(ts2.tv_nsec == 750000000);
+
+  ts.tv_sec = 4;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  UTI_AverageDiffTimespecs(&ts, &ts2, &ts3, &x);
+  TEST_CHECK(ts3.tv_sec == 3);
+  TEST_CHECK(ts3.tv_nsec == 125000000);
+  TEST_CHECK(x == -2.75);
+
+  ts.tv_sec = 4;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 1;
+  ts2.tv_nsec = 750000000;
+  ts3.tv_sec = 5;
+  ts3.tv_nsec = 250000000;
+  UTI_AddDiffToTimespec(&ts, &ts2, &ts3, &ts4);
+  TEST_CHECK(ts4.tv_sec == 8);
+  TEST_CHECK(ts4.tv_nsec == 0);
+
+  ts.tv_sec = 1600000000;
+  ts.tv_nsec = 123;
+  s = UTI_TimespecToString(&ts);
+  TEST_CHECK(strcmp(s, "1600000000.000000123") == 0);
+
+  ntp_ts.hi = 1;
+  ntp_ts.hi = 2;
+  UTI_Ntp64ToTimespec(&ntp_ts, &ts);
+  s = UTI_Ntp64ToString(&ntp_ts);
+  s2 = UTI_TimespecToString(&ts);
+  TEST_CHECK(strcmp(s, s2) == 0);
+
+  s = UTI_RefidToString(0x41424344);
+  TEST_CHECK(strcmp(s, "ABCD") == 0);
+
+  ip.family = IPADDR_UNSPEC;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "[UNSPEC]") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_INET4;
+  ip.addr.in4 = 0x7f010203;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "127.1.2.3") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0x7f010203);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_INET6;
+  memset(&ip.addr.in6, 0, sizeof (ip.addr.in6));
+  ip.addr.in6[0] = 0xab;
+  ip.addr.in6[15] = 0xcd;
+  s = UTI_IPToString(&ip);
+#ifdef FEAT_IPV6
+  TEST_CHECK(strcmp(s, "ab00::cd") == 0);
+#else
+  TEST_CHECK(strcmp(s, "ab00:0000:0000:0000:0000:0000:0000:00cd") == 0);
+#endif
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0x5f9aa602);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_ID;
+  ip.addr.id = 12345;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "ID#0000012345") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  ip.family = IPADDR_UNSPEC + 10;
+  s = UTI_IPToString(&ip);
+  TEST_CHECK(strcmp(s, "[UNKNOWN]") == 0);
+  TEST_CHECK(UTI_IPToRefid(&ip) == 0);
+  TEST_CHECK(UTI_IPToHash(&ip) == UTI_IPToHash(&ip));
+
+  TEST_CHECK(UTI_StringToIP("200.4.5.6", &ip));
+  TEST_CHECK(ip.family == IPADDR_INET4);
+  TEST_CHECK(ip.addr.in4 == 0xc8040506);
+
+#ifdef FEAT_IPV6
+  TEST_CHECK(UTI_StringToIP("1234::7890", &ip));
+  TEST_CHECK(ip.family == IPADDR_INET6);
+  TEST_CHECK(ip.addr.in6[0] == 0x12 && ip.addr.in6[1] == 0x34);
+  TEST_CHECK(ip.addr.in6[2] == 0x00 && ip.addr.in6[13] == 0x00);
+  TEST_CHECK(ip.addr.in6[14] == 0x78 && ip.addr.in6[15] == 0x90);
+#else
+  TEST_CHECK(!UTI_StringToIP("1234::7890", &ip));
+#endif
+
+  TEST_CHECK(!UTI_StringToIP("ID#0000012345", &ip));
+
+  TEST_CHECK(UTI_IsStringIP("1.2.3.4"));
+  TEST_CHECK(!UTI_IsStringIP("127.3.3"));
+  TEST_CHECK(!UTI_IsStringIP("127.3"));
+  TEST_CHECK(!UTI_IsStringIP("127"));
+#ifdef FEAT_IPV6
+  TEST_CHECK(UTI_IsStringIP("1234:5678::aaaa"));
+#else
+  TEST_CHECK(!UTI_IsStringIP("1234:5678::aaaa"));
+#endif
+  TEST_CHECK(!UTI_StringToIP("ID#0000012345", &ip));
+
+  TEST_CHECK(!UTI_StringToIdIP("1.2.3.4", &ip));
+  TEST_CHECK(UTI_StringToIdIP("ID#0000056789", &ip));
+  TEST_CHECK(ip.family == IPADDR_ID);
+  TEST_CHECK(ip.addr.id == 56789);
+
+  for (i = IPADDR_UNSPEC; i <= IPADDR_ID + 1; i++) {
+    ip.family = i;
+    TEST_CHECK(UTI_IsIPReal(&ip) == (i == IPADDR_INET4 || i == IPADDR_INET6));
+  }
+
+  ip.family = IPADDR_UNSPEC;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_UNSPEC));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_UNSPEC);
+
+  ip.family = IPADDR_INET4;
+  ip.addr.in4 = 0x12345678;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_INET4));
+  TEST_CHECK(ip2.addr.in4 == htonl(0x12345678));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_INET4);
+  TEST_CHECK(ip3.addr.in4 == 0x12345678);
+
+  ip.family = IPADDR_INET6;
+  for (i = 0; i < 16; i++)
+    ip.addr.in6[i] = i;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_INET6));
+  for (i = 0; i < 16; i++)
+    TEST_CHECK(ip.addr.in6[i] == i);
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_INET6);
+  for (i = 0; i < 16; i++)
+    TEST_CHECK(ip.addr.in6[i] == i);
+
+  ip.family = IPADDR_ID;
+  ip.addr.in4 = 0x87654321;
+  UTI_IPHostToNetwork(&ip, &ip2);
+  TEST_CHECK(ip2.family == htons(IPADDR_ID));
+  TEST_CHECK(ip2.addr.in4 == htonl(0x87654321));
+  UTI_IPNetworkToHost(&ip2, &ip3);
+  TEST_CHECK(ip3.family == IPADDR_ID);
+  TEST_CHECK(ip3.addr.in4 == 0x87654321);
+
+  for (i = 0; i < 16; i++)
+    ip.addr.in6[i] = 0x80;
+  ip2 = ip;
+
+  for (i = IPADDR_UNSPEC; i <= IPADDR_ID; i++) {
+    ip.family = i;
+    ip2.family = i + 1;
+    TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) < 0);
+    TEST_CHECK(UTI_CompareIPs(&ip2, &ip, NULL) > 0);
+    ip2 = ip;
+    ip2.addr.in4++;
+    if (i == IPADDR_UNSPEC) {
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) == 0);
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) == 0);
+    } else {
+      TEST_CHECK(UTI_CompareIPs(&ip, &ip2, NULL) < 0);
+      TEST_CHECK(UTI_CompareIPs(&ip2, &ip, NULL) > 0);
+      if (i == IPADDR_ID) {
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) < 0);
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip2) < 0);
+      } else {
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip) == 0);
+        TEST_CHECK(UTI_CompareIPs(&ip, &ip2, &ip2) < 0);
+      }
+    }
+  }
+
+  ip_saddr.ip_addr.family = IPADDR_INET4;
+  ip_saddr.ip_addr.addr.in4 = 0x01020304;
+  ip_saddr.port = 12345;
+  s = UTI_IPSockAddrToString(&ip_saddr);
+  TEST_CHECK(strcmp(s, "1.2.3.4:12345") == 0);
+
+  ip = ip_saddr.ip_addr;
+  s = UTI_IPSubnetToString(&ip, 10);
+  TEST_CHECK(strcmp(s, "1.2.3.4/10") == 0);
+  s = UTI_IPSubnetToString(&ip, 32);
+  TEST_CHECK(strcmp(s, "1.2.3.4") == 0);
+  ip.family = IPADDR_UNSPEC;
+  s = UTI_IPSubnetToString(&ip, 0);
+  TEST_CHECK(strcmp(s, "any address") == 0);
+
+  s = UTI_TimeToLogForm(2000000000);
+  TEST_CHECK(strcmp(s, "2033-05-18 03:33:20") == 0);
+
+  ts.tv_sec = 3;
+  ts.tv_nsec = 500000000;
+  ts2.tv_sec = 4;
+  ts2.tv_nsec = 250000000;
+  UTI_AdjustTimespec(&ts, &ts2, &ts3, &x, 2.0, -5.0);
+  TEST_CHECK(fabs(x - 6.5) < 1.0e-15);
+  TEST_CHECK((ts3.tv_sec == 10 && ts3.tv_nsec == 0) ||
+             (ts3.tv_sec == 9 && ts3.tv_nsec == 999999999));
+
+  for (i = -32; i <= 32; i++) {
+    for (j = c = 0; j < 1000; j++) {
+      UTI_GetNtp64Fuzz(&ntp_fuzz, i);
+      if (i <= 0)
+        TEST_CHECK(ntp_fuzz.hi == 0);
+      if (i < 0)
+        TEST_CHECK(ntohl(ntp_fuzz.lo) < 1U << (32 + i));
+      else if (i < 32)
+        TEST_CHECK(ntohl(ntp_fuzz.hi) < 1U << i);
+      if (ntohl(ntp_fuzz.lo) >= 1U << (31 + CLAMP(-31, i, 0)))
+        c++;
+    }
+
+    if (i == -32)
+      TEST_CHECK(c == 0);
+    else
+      TEST_CHECK(c > 400 && c < 600);
+  }
+
+  TEST_CHECK(UTI_DoubleToNtp32(-1.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32(1e-9) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32(32768.0) == htonl(0x80000000));
+  TEST_CHECK(UTI_DoubleToNtp32(65536.0) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32(65537.0) == htonl(0xffffffff));
+
+  TEST_CHECK(UTI_DoubleToNtp32f28(-1.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32f28(0.0) == htonl(0));
+  TEST_CHECK(UTI_DoubleToNtp32f28(1e-9) == htonl(1));
+  TEST_CHECK(UTI_DoubleToNtp32f28(4e-9) == htonl(2));
+  TEST_CHECK(UTI_DoubleToNtp32f28(8.0) == htonl(0x80000000));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.0) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.1) == htonl(0xffffffff));
+  TEST_CHECK(UTI_DoubleToNtp32f28(16.1) == htonl(0xffffffff));
+
+  TEST_CHECK(UTI_Ntp32f28ToDouble(htonl(0xffffffff)) >= 65535.999);
+  for (i = 0; i < 100000; i++) {
+    UTI_GetRandomBytes(&ntp32_ts, sizeof (ntp32_ts));
+    TEST_CHECK(UTI_DoubleToNtp32(UTI_Ntp32ToDouble(ntp32_ts)) == ntp32_ts);
+    TEST_CHECK(UTI_DoubleToNtp32f28(UTI_Ntp32f28ToDouble(ntp32_ts)) == ntp32_ts);
+  }
+
+  ts.tv_nsec = 0;
+
+  ts.tv_sec = 10;
+  TEST_CHECK(!UTI_IsTimeOffsetSane(&ts, -20.0));
+
+#ifdef HAVE_LONG_TIME_T
+  ts.tv_sec = NTP_ERA_SPLIT + (1LL << 32);
+#else
+  ts.tv_sec = 0x7fffffff - MIN_ENDOFTIME_DISTANCE;
+#endif
+  TEST_CHECK(!UTI_IsTimeOffsetSane(&ts, 10.0));
+  TEST_CHECK(UTI_IsTimeOffsetSane(&ts, -20.0));
+
+  TEST_CHECK(UTI_Log2ToDouble(-1) == 0.5);
+  TEST_CHECK(UTI_Log2ToDouble(0) == 1.0);
+  TEST_CHECK(UTI_Log2ToDouble(1) == 2.0);
+  TEST_CHECK(UTI_Log2ToDouble(-31) < UTI_Log2ToDouble(-30));
+  TEST_CHECK(UTI_Log2ToDouble(-32) == UTI_Log2ToDouble(-31));
+  TEST_CHECK(UTI_Log2ToDouble(30) < UTI_Log2ToDouble(32));
+  TEST_CHECK(UTI_Log2ToDouble(31) == UTI_Log2ToDouble(32));
+
+  UTI_TimespecHostToNetwork(&ts, &tspec);
+#ifdef HAVE_LONG_TIME_T
+  TEST_CHECK(tspec.tv_sec_high == htonl(ts.tv_sec >> 32));
+#else
+  TEST_CHECK(tspec.tv_sec_high == htonl(TV_NOHIGHSEC));
+#endif
+  TEST_CHECK(tspec.tv_sec_low == htonl(ts.tv_sec));
+  TEST_CHECK(tspec.tv_nsec == htonl(ts.tv_nsec));
+  UTI_TimespecNetworkToHost(&tspec, &ts2);
+  TEST_CHECK(!UTI_CompareTimespecs(&ts, &ts2));
+
+  integer64 = UTI_Integer64HostToNetwork(0x1234567890ABCDEFULL);
+  TEST_CHECK(memcmp(&integer64, "\x12\x34\x56\x78\x90\xab\xcd\xef", 8) == 0);
+  TEST_CHECK(UTI_Integer64NetworkToHost(integer64) == 0x1234567890ABCDEFULL);
+
+  TEST_CHECK(UTI_CmacNameToAlgorithm("AES128") == CMC_AES128);
+  TEST_CHECK(UTI_CmacNameToAlgorithm("AES256") == CMC_AES256);
+  TEST_CHECK(UTI_CmacNameToAlgorithm("NOSUCHCMAC") == CMC_INVALID);
+
+  TEST_CHECK(UTI_HashNameToAlgorithm("MD5") == HSH_MD5);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA1") == HSH_SHA1);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA256") == HSH_SHA256);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA384") == HSH_SHA384);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA512") == HSH_SHA512);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-224") == HSH_SHA3_224);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-256") == HSH_SHA3_256);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-384") == HSH_SHA3_384);
+  TEST_CHECK(UTI_HashNameToAlgorithm("SHA3-512") == HSH_SHA3_512);
+  TEST_CHECK(UTI_HashNameToAlgorithm("TIGER") == HSH_TIGER);
+  TEST_CHECK(UTI_HashNameToAlgorithm("WHIRLPOOL") == HSH_WHIRLPOOL);
+  TEST_CHECK(UTI_HashNameToAlgorithm("NOSUCHHASH") == HSH_INVALID);
+
+  i = open("/dev/null", 0);
+  TEST_CHECK(UTI_FdSetCloexec(i));
+  j = fcntl(i, F_GETFD);
+  TEST_CHECK(j & F_GETFD);
+  close(i);
+
+  UTI_SetQuitSignalsHandler(handle_signal, 0);
+  TEST_CHECK(handled_signal == 0);
+  kill(getpid(), SIGPIPE);
+  while (handled_signal == 0)
+    ;
+  TEST_CHECK(handled_signal == SIGPIPE);
+
+  s = UTI_PathToDir("/aaa/bbb/ccc/ddd");
+  TEST_CHECK(!strcmp(s, "/aaa/bbb/ccc"));
+  Free(s);
+  s = UTI_PathToDir("aaa");
+  TEST_CHECK(!strcmp(s, "."));
+  Free(s);
+  s = UTI_PathToDir("/aaaa");
+  TEST_CHECK(!strcmp(s, "/"));
+  Free(s);
+
+  nan = strtod("nan", NULL);
+  inf = strtod("inf", NULL);
+
+  TEST_CHECK(MIN(2.0, -1.0) == -1.0);
+  TEST_CHECK(MIN(-1.0, 2.0) == -1.0);
+  TEST_CHECK(MIN(inf, 2.0) == 2.0);
+
+  TEST_CHECK(MAX(2.0, -1.0) == 2.0);
+  TEST_CHECK(MAX(-1.0, 2.0) == 2.0);
+  TEST_CHECK(MAX(inf, 2.0) == inf);
+
+  TEST_CHECK(CLAMP(1.0, -1.0, 2.0) == 1.0);
+  TEST_CHECK(CLAMP(1.0, 3.0, 2.0) == 2.0);
+  TEST_CHECK(CLAMP(1.0, inf, 2.0) == 2.0);
+  TEST_CHECK(CLAMP(1.0, nan, 2.0) == 2.0);
+
+  TEST_CHECK(SQUARE(3.0) == 3.0 * 3.0);
+
+  rmdir("testdir");
+
+  uid = geteuid();
+  gid = getegid();
+
+  TEST_CHECK(UTI_CreateDirAndParents("testdir", 0700, uid, gid));
+
+  TEST_CHECK(UTI_CheckDirPermissions("testdir", 0700, uid, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0300, uid, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0700, uid + 1, gid));
+  TEST_CHECK(!UTI_CheckDirPermissions("testdir", 0700, uid, gid + 1));
+
+  umask(0);
+
+  unlink("testfile");
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'r', 0);
+  TEST_CHECK(!file);
+  TEST_CHECK(stat("testfile", &st) < 0);
+
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'w', 0644);
+  TEST_CHECK(file);
+  TEST_CHECK(stat("testfile", &st) == 0);
+  TEST_CHECK((st.st_mode & 0777) == 0644);
+  fclose(file);
+
+  file = UTI_OpenFile(".", "test", "file", 'W', 0640);
+  TEST_CHECK(file);
+  TEST_CHECK(stat("testfile", &st) == 0);
+  TEST_CHECK((st.st_mode & 0777) == 0640);
+  fclose(file);
+
+  file = UTI_OpenFile(NULL, "test", "file", 'r', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RenameTempFile(NULL, "testfil", "e", NULL));
+  TEST_CHECK(stat("testfil", &st) == 0);
+  file = UTI_OpenFile(NULL, "testfil", NULL, 'R', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RenameTempFile(NULL, "test", "fil", "file"));
+  TEST_CHECK(stat("testfile", &st) == 0);
+  file = UTI_OpenFile(NULL, "testfile", NULL, 'R', 0);
+  TEST_CHECK(file);
+  fclose(file);
+
+  TEST_CHECK(UTI_RemoveFile(NULL, "testfile", NULL));
+  TEST_CHECK(stat("testfile", &st) < 0);
+  TEST_CHECK(!UTI_RemoveFile(NULL, "testfile", NULL));
+
+  for (i = c = 0; i < 100000; i++) {
+    j = random() % (sizeof (buf) + 1);
+    UTI_GetRandomBytesUrandom(buf, j);
+    if (j && buf[j - 1] % 2)
+      c++;
+    if (random() % 10000 == 0) {
+      UTI_ResetGetRandomFunctions();
+      TEST_CHECK(!urandom_file);
+    }
+  }
+  TEST_CHECK(c > 46000 && c < 48000);
+
+  for (i = c = 0; i < 100000; i++) {
+    j = random() % (sizeof (buf) + 1);
+    UTI_GetRandomBytes(buf, j);
+    if (j && buf[j - 1] % 2)
+      c++;
+    if (random() % 10000 == 0) {
+      UTI_ResetGetRandomFunctions();
+#if HAVE_GETRANDOM
+      TEST_CHECK(getrandom_buf_available == 0);
+#endif
+    }
+  }
+  TEST_CHECK(c > 46000 && c < 48000);
+
+  assert(sizeof (buf) >= 16);
+  TEST_CHECK(UTI_HexToBytes("", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("0", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF", buf, sizeof (buf)) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, 8) == 0);
+  TEST_CHECK(UTI_HexToBytes("00123456789ABCDEF0", buf, sizeof (buf)) == 9);
+  TEST_CHECK(memcmp(buf, "\x00\x12\x34\x56\x78\x9A\xBC\xDE\xF0", 9) == 0);
+  memcpy(buf, "AB123456780001", 15);
+  TEST_CHECK(UTI_HexToBytes(buf, buf, sizeof (buf)) == 7);
+  TEST_CHECK(memcmp(buf, "\xAB\x12\x34\x56\x78\x00\x01", 7) == 0);
+
+  TEST_CHECK(UTI_BytesToHex("", 0, buf, 0) == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 14) == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 7, buf, 15) == 1);
+  TEST_CHECK(strcmp(buf, "AB123456780001") == 0);
+  TEST_CHECK(UTI_BytesToHex("\xAB\x12\x34\x56\x78\x00\x01", 0, buf, 15) == 1);
+  TEST_CHECK(strcmp(buf, "") == 0);
+
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 0);
+  TEST_CHECK(!words[0]);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "     ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 0);
+  TEST_CHECK(!words[0]);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a  \n ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 0);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "  a  ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 2);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", " \n  a") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 1);
+  TEST_CHECK(words[0] == buf + 4);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a   b") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 1) == 2);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", "a   b") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 2) == 2);
+  TEST_CHECK(words[0] == buf + 0);
+  TEST_CHECK(words[1] == buf + 4);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(strcmp(words[1], "b") == 0);
+  TEST_CHECK(snprintf(buf, sizeof (buf), "%s", " a b ") < sizeof (buf));
+  TEST_CHECK(UTI_SplitString(buf, words, 3) == 2);
+  TEST_CHECK(words[0] == buf + 1);
+  TEST_CHECK(words[1] == buf + 3);
+  TEST_CHECK(strcmp(words[0], "a") == 0);
+  TEST_CHECK(strcmp(words[1], "b") == 0);
+
+  HSH_Finalise();
+}
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..a240e3e
--- /dev/null
+++ b/util.c
@@ -0,0 +1,1623 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * Copyright (C) Miroslav Lichvar  2009, 2012-2023
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Various utility functions
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "logging.h"
+#include "memory.h"
+#include "util.h"
+#include "hash.h"
+
+#define NSEC_PER_SEC 1000000000
+
+/* ================================================== */
+
+void
+UTI_ZeroTimespec(struct timespec *ts)
+{
+  ts->tv_sec = 0;
+  ts->tv_nsec = 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsZeroTimespec(struct timespec *ts)
+{
+  return !ts->tv_sec && !ts->tv_nsec;
+}
+
+/* ================================================== */
+
+void
+UTI_TimevalToTimespec(const struct timeval *tv, struct timespec *ts)
+{
+  ts->tv_sec = tv->tv_sec;
+  ts->tv_nsec = 1000 * tv->tv_usec;
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecToTimeval(const struct timespec *ts, struct timeval *tv)
+{
+  tv->tv_sec = ts->tv_sec;
+  tv->tv_usec = ts->tv_nsec / 1000;
+}
+
+/* ================================================== */
+
+double
+UTI_TimespecToDouble(const struct timespec *ts)
+{
+  return ts->tv_sec + 1.0e-9 * ts->tv_nsec;
+}
+
+/* ================================================== */
+
+void
+UTI_DoubleToTimespec(double d, struct timespec *ts)
+{
+  ts->tv_sec = d;
+  ts->tv_nsec = 1.0e9 * (d - ts->tv_sec);
+  UTI_NormaliseTimespec(ts);
+}
+
+/* ================================================== */
+
+void
+UTI_NormaliseTimespec(struct timespec *ts)
+{
+  if (ts->tv_nsec >= NSEC_PER_SEC || ts->tv_nsec < 0) {
+    ts->tv_sec += ts->tv_nsec / NSEC_PER_SEC;
+    ts->tv_nsec = ts->tv_nsec % NSEC_PER_SEC;
+
+    /* If seconds are negative nanoseconds would end up negative too */
+    if (ts->tv_nsec < 0) {
+      ts->tv_sec--;
+      ts->tv_nsec += NSEC_PER_SEC;
+    }
+  }
+}
+
+/* ================================================== */
+
+double
+UTI_TimevalToDouble(const struct timeval *tv)
+{
+  return tv->tv_sec + 1.0e-6 * tv->tv_usec;
+}
+
+/* ================================================== */
+
+void
+UTI_DoubleToTimeval(double a, struct timeval *b)
+{
+  double frac_part;
+
+  b->tv_sec = a;
+  frac_part = 1.0e6 * (a - b->tv_sec);
+  b->tv_usec = round(frac_part);
+  UTI_NormaliseTimeval(b);
+}
+
+/* ================================================== */
+
+void
+UTI_NormaliseTimeval(struct timeval *x)
+{
+  /* Reduce tv_usec to within +-1000000 of zero. JGH */
+  if ((x->tv_usec >= 1000000) || (x->tv_usec <= -1000000)) {
+    x->tv_sec += x->tv_usec/1000000;
+    x->tv_usec = x->tv_usec%1000000;
+  }
+
+  /* Make tv_usec positive. JGH */
+   if (x->tv_usec < 0) {
+    --x->tv_sec;
+    x->tv_usec += 1000000;
+ }
+
+}
+
+/* ================================================== */
+
+int
+UTI_CompareTimespecs(const struct timespec *a, const struct timespec *b)
+{
+  if (a->tv_sec < b->tv_sec)
+    return -1;
+  if (a->tv_sec > b->tv_sec)
+    return 1;
+  if (a->tv_nsec < b->tv_nsec)
+    return -1;
+  if (a->tv_nsec > b->tv_nsec)
+    return 1;
+  return 0;
+}
+
+/* ================================================== */
+
+void
+UTI_DiffTimespecs(struct timespec *result, const struct timespec *a, const struct timespec *b)
+{
+  result->tv_sec = a->tv_sec - b->tv_sec;
+  result->tv_nsec = a->tv_nsec - b->tv_nsec;
+  UTI_NormaliseTimespec(result);
+}
+
+/* ================================================== */
+
+/* Calculate result = a - b and return as a double */
+double
+UTI_DiffTimespecsToDouble(const struct timespec *a, const struct timespec *b)
+{
+  return ((double)a->tv_sec - (double)b->tv_sec) + 1.0e-9 * (a->tv_nsec - b->tv_nsec);
+}
+
+/* ================================================== */
+
+void
+UTI_AddDoubleToTimespec(const struct timespec *start, double increment, struct timespec *end)
+{
+  time_t int_part;
+
+  int_part = increment;
+  end->tv_sec = start->tv_sec + int_part;
+  end->tv_nsec = start->tv_nsec + 1.0e9 * (increment - int_part);
+  UTI_NormaliseTimespec(end);
+}
+
+/* ================================================== */
+
+/* Calculate the average and difference (as a double) of two timespecs */
+void
+UTI_AverageDiffTimespecs(const struct timespec *earlier, const struct timespec *later,
+                         struct timespec *average, double *diff)
+{
+  *diff = UTI_DiffTimespecsToDouble(later, earlier);
+  UTI_AddDoubleToTimespec(earlier, *diff / 2.0, average);
+}
+
+/* ================================================== */
+
+void
+UTI_AddDiffToTimespec(const struct timespec *a, const struct timespec *b,
+                      const struct timespec *c, struct timespec *result)
+{
+  double diff;
+
+  diff = UTI_DiffTimespecsToDouble(a, b);
+  UTI_AddDoubleToTimespec(c, diff, result);
+}
+
+/* ================================================== */
+
+#define POOL_ENTRIES 16
+#define BUFFER_LENGTH 64
+static char buffer_pool[POOL_ENTRIES][BUFFER_LENGTH];
+static int  pool_ptr = 0;
+
+#define NEXT_BUFFER (buffer_pool[pool_ptr = ((pool_ptr + 1) % POOL_ENTRIES)])
+
+/* ================================================== */
+/* Convert a timespec into a temporary string, largely for diagnostic display */
+
+char *
+UTI_TimespecToString(const struct timespec *ts)
+{
+  char *result;
+
+  result = NEXT_BUFFER;
+#ifdef HAVE_LONG_TIME_T
+  snprintf(result, BUFFER_LENGTH, "%"PRId64".%09lu",
+           (int64_t)ts->tv_sec, (unsigned long)ts->tv_nsec);
+#else
+  snprintf(result, BUFFER_LENGTH, "%ld.%09lu",
+           (long)ts->tv_sec, (unsigned long)ts->tv_nsec);
+#endif
+  return result;
+}
+
+/* ================================================== */
+/* Convert an NTP timestamp into a temporary string, largely
+   for diagnostic display */
+
+char *
+UTI_Ntp64ToString(const NTP_int64 *ntp_ts)
+{
+  struct timespec ts;
+  UTI_Ntp64ToTimespec(ntp_ts, &ts);
+  return UTI_TimespecToString(&ts);
+}
+
+/* ================================================== */
+
+char *
+UTI_RefidToString(uint32_t ref_id)
+{
+  unsigned int i, j, c;
+  char *result;
+
+  result = NEXT_BUFFER;
+
+  for (i = j = 0; i < 4 && i < BUFFER_LENGTH - 1; i++) {
+    c = (ref_id >> (24 - i * 8)) & 0xff;
+    if (isprint(c))
+      result[j++] = c;
+  }
+
+  result[j] = '\0';
+
+  return result;
+}
+
+/* ================================================== */
+
+char *
+UTI_IPToString(const IPAddr *addr)
+{
+  unsigned long a, b, c, d, ip;
+  const uint8_t *ip6;
+  char *result;
+
+  result = NEXT_BUFFER;
+  switch (addr->family) {
+    case IPADDR_UNSPEC:
+      snprintf(result, BUFFER_LENGTH, "[UNSPEC]");
+      break;
+    case IPADDR_INET4:
+      ip = addr->addr.in4;
+      a = (ip>>24) & 0xff;
+      b = (ip>>16) & 0xff;
+      c = (ip>> 8) & 0xff;
+      d = (ip>> 0) & 0xff;
+      snprintf(result, BUFFER_LENGTH, "%lu.%lu.%lu.%lu", a, b, c, d);
+      break;
+    case IPADDR_INET6:
+      ip6 = addr->addr.in6;
+#ifdef FEAT_IPV6
+      inet_ntop(AF_INET6, ip6, result, BUFFER_LENGTH);
+#else
+      assert(BUFFER_LENGTH >= 40);
+      for (a = 0; a < 8; a++)
+        snprintf(result + a * 5, 40 - a * 5, "%04x:",
+                 (unsigned int)(ip6[2 * a] << 8 | ip6[2 * a + 1]));
+#endif
+      break;
+    case IPADDR_ID:
+      snprintf(result, BUFFER_LENGTH, "ID#%010"PRIu32, addr->addr.id);
+      break;
+    default:
+      snprintf(result, BUFFER_LENGTH, "[UNKNOWN]");
+  }
+  return result;
+}
+
+/* ================================================== */
+
+int
+UTI_StringToIP(const char *addr, IPAddr *ip)
+{
+  struct in_addr in4;
+#ifdef FEAT_IPV6
+  struct in6_addr in6;
+#endif
+
+  if (inet_pton(AF_INET, addr, &in4) > 0) {
+    ip->family = IPADDR_INET4;
+    ip->_pad = 0;
+    ip->addr.in4 = ntohl(in4.s_addr);
+    return 1;
+  }
+
+#ifdef FEAT_IPV6
+  if (inet_pton(AF_INET6, addr, &in6) > 0) {
+    ip->family = IPADDR_INET6;
+    ip->_pad = 0;
+    memcpy(ip->addr.in6, in6.s6_addr, sizeof (ip->addr.in6));
+    return 1;
+  }
+#endif
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsStringIP(const char *string)
+{
+  IPAddr ip;
+
+  return UTI_StringToIP(string, &ip);
+}
+
+/* ================================================== */
+
+int
+UTI_StringToIdIP(const char *addr, IPAddr *ip)
+{
+  if (sscanf(addr, "ID#%"SCNu32, &ip->addr.id) == 1) {
+    ip->family = IPADDR_ID;
+    ip->_pad = 0;
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_IsIPReal(const IPAddr *ip)
+{
+  switch (ip->family) {
+    case IPADDR_INET4:
+    case IPADDR_INET6:
+      return 1;
+    default:
+      return 0;
+  }
+}
+
+/* ================================================== */
+
+uint32_t
+UTI_IPToRefid(const IPAddr *ip)
+{
+  static int MD5_hash = -1;
+  unsigned char buf[16];
+
+  switch (ip->family) {
+    case IPADDR_INET4:
+      return ip->addr.in4;
+    case IPADDR_INET6:
+      if (MD5_hash < 0)
+        MD5_hash = HSH_GetHashId(HSH_MD5_NONCRYPTO);
+
+      if (MD5_hash < 0 ||
+          HSH_Hash(MD5_hash, (const unsigned char *)ip->addr.in6, sizeof (ip->addr.in6),
+                   NULL, 0, buf, sizeof (buf)) != sizeof (buf))
+        LOG_FATAL("Could not get MD5");
+
+      return (uint32_t)buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+uint32_t
+UTI_IPToHash(const IPAddr *ip)
+{
+  static uint32_t seed = 0;
+  const unsigned char *addr;
+  unsigned int i, len;
+  uint32_t hash;
+
+  switch (ip->family) {
+    case IPADDR_INET4:
+      addr = (unsigned char *)&ip->addr.in4;
+      len = sizeof (ip->addr.in4);
+      break;
+    case IPADDR_INET6:
+      addr = ip->addr.in6;
+      len = sizeof (ip->addr.in6);
+      break;
+    case IPADDR_ID:
+      addr = (unsigned char *)&ip->addr.id;
+      len = sizeof (ip->addr.id);
+      break;
+    default:
+      return 0;
+  }
+
+  /* Include a random seed in the hash to randomize collisions
+     and order of addresses in hash tables */
+  while (!seed)
+    UTI_GetRandomBytes(&seed, sizeof (seed));
+
+  for (i = 0, hash = seed; i < len; i++)
+    hash = 71 * hash + addr[i];
+
+  return hash + seed;
+}
+
+/* ================================================== */
+
+void
+UTI_IPHostToNetwork(const IPAddr *src, IPAddr *dest)
+{
+  /* Don't send uninitialized bytes over network */
+  memset(dest, 0, sizeof (IPAddr));
+
+  dest->family = htons(src->family);
+
+  switch (src->family) {
+    case IPADDR_INET4:
+      dest->addr.in4 = htonl(src->addr.in4);
+      break;
+    case IPADDR_INET6:
+      memcpy(dest->addr.in6, src->addr.in6, sizeof (dest->addr.in6));
+      break;
+    case IPADDR_ID:
+      dest->addr.id = htonl(src->addr.id);
+      break;
+    default:
+      dest->family = htons(IPADDR_UNSPEC);
+  }
+}
+
+/* ================================================== */
+
+void
+UTI_IPNetworkToHost(const IPAddr *src, IPAddr *dest)
+{
+  dest->family = ntohs(src->family);
+  dest->_pad = 0;
+
+  switch (dest->family) {
+    case IPADDR_INET4:
+      dest->addr.in4 = ntohl(src->addr.in4);
+      break;
+    case IPADDR_INET6:
+      memcpy(dest->addr.in6, src->addr.in6, sizeof (dest->addr.in6));
+      break;
+    case IPADDR_ID:
+      dest->addr.id = ntohl(src->addr.id);
+      break;
+    default:
+      dest->family = IPADDR_UNSPEC;
+  }
+}
+
+/* ================================================== */
+
+int
+UTI_CompareIPs(const IPAddr *a, const IPAddr *b, const IPAddr *mask)
+{
+  int i, d;
+
+  if (a->family != b->family)
+    return a->family - b->family;
+
+  if (mask && mask->family != b->family)
+    mask = NULL;
+
+  switch (a->family) {
+    case IPADDR_UNSPEC:
+      return 0;
+    case IPADDR_INET4:
+      if (mask)
+        return (a->addr.in4 & mask->addr.in4) - (b->addr.in4 & mask->addr.in4);
+      else
+        return a->addr.in4 - b->addr.in4;
+    case IPADDR_INET6:
+      for (i = 0, d = 0; !d && i < 16; i++) {
+        if (mask)
+          d = (a->addr.in6[i] & mask->addr.in6[i]) -
+              (b->addr.in6[i] & mask->addr.in6[i]);
+        else
+          d = a->addr.in6[i] - b->addr.in6[i];
+      }
+      return d;
+    case IPADDR_ID:
+      return a->addr.id - b->addr.id;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+char *
+UTI_IPSockAddrToString(const IPSockAddr *sa)
+{
+  char *result;
+
+  result = NEXT_BUFFER;
+  snprintf(result, BUFFER_LENGTH,
+           sa->ip_addr.family != IPADDR_INET6 ? "%s:%hu" : "[%s]:%hu",
+           UTI_IPToString(&sa->ip_addr), sa->port);
+
+  return result;
+}
+
+/* ================================================== */
+
+char *
+UTI_IPSubnetToString(IPAddr *subnet, int bits)
+{
+  char *result;
+
+  result = NEXT_BUFFER;
+
+  if (subnet->family == IPADDR_UNSPEC)
+    snprintf(result, BUFFER_LENGTH, "%s", "any address");
+  else if ((subnet->family == IPADDR_INET4 && bits == 32) ||
+           (subnet->family == IPADDR_INET6 && bits == 128))
+    snprintf(result, BUFFER_LENGTH, "%s", UTI_IPToString(subnet));
+  else
+    snprintf(result, BUFFER_LENGTH, "%s/%d", UTI_IPToString(subnet), bits);
+
+  return result;
+}
+
+/* ================================================== */
+
+char *
+UTI_TimeToLogForm(time_t t)
+{
+  struct tm *stm;
+  char *result;
+
+  result = NEXT_BUFFER;
+
+  stm = gmtime(&t);
+
+  if (stm)
+    strftime(result, BUFFER_LENGTH, "%Y-%m-%d %H:%M:%S", stm);
+  else
+    snprintf(result, BUFFER_LENGTH, "INVALID    INVALID ");
+
+  return result;
+}
+
+/* ================================================== */
+
+void
+UTI_AdjustTimespec(const struct timespec *old_ts, const struct timespec *when,
+                   struct timespec *new_ts, double *delta_time, double dfreq, double doffset)
+{
+  double elapsed;
+
+  elapsed = UTI_DiffTimespecsToDouble(when, old_ts);
+  *delta_time = elapsed * dfreq - doffset;
+  UTI_AddDoubleToTimespec(old_ts, *delta_time, new_ts);
+}
+
+/* ================================================== */
+
+void
+UTI_GetNtp64Fuzz(NTP_int64 *ts, int precision)
+{
+  int start, bits;
+
+  assert(precision >= -32 && precision <= 32);
+  assert(sizeof (*ts) == 8);
+
+  start = sizeof (*ts) - (precision + 32 + 7) / 8;
+  ts->hi = ts->lo = 0;
+
+  UTI_GetRandomBytes((unsigned char *)ts + start, sizeof (*ts) - start);
+
+  bits = (precision + 32) % 8;
+  if (bits)
+    ((unsigned char *)ts)[start] %= 1U << bits;
+}
+
+/* ================================================== */
+
+double
+UTI_Ntp32ToDouble(NTP_int32 x)
+{
+  return (double) ntohl(x) / 65536.0;
+}
+
+/* ================================================== */
+
+#define MAX_NTP_INT32 (4294967295.0 / 65536.0)
+
+NTP_int32
+UTI_DoubleToNtp32(double x)
+{
+  NTP_int32 r;
+
+  if (x >= MAX_NTP_INT32) {
+    r = 0xffffffff;
+  } else if (x <= 0.0) {
+    r = 0;
+  } else {
+    x *= 65536.0;
+    r = x;
+
+    /* Round up */
+    if (r < x)
+      r++;
+  }
+
+  return htonl(r);
+}
+
+/* ================================================== */
+
+double
+UTI_Ntp32f28ToDouble(NTP_int32 x)
+{
+  uint32_t r = ntohl(x);
+
+  /* Maximum value is special */
+  if (r == 0xffffffff)
+    return MAX_NTP_INT32;
+
+  return r / (double)(1U << 28);
+}
+
+/* ================================================== */
+
+NTP_int32
+UTI_DoubleToNtp32f28(double x)
+{
+  NTP_int32 r;
+
+  if (x >= 4294967295.0 / (1U << 28)) {
+    r = 0xffffffff;
+  } else if (x <= 0.0) {
+    r = 0;
+  } else {
+    x *= 1U << 28;
+    r = x;
+
+    /* Round up */
+    if (r < x)
+      r++;
+  }
+
+  return htonl(r);
+}
+
+/* ================================================== */
+
+void
+UTI_ZeroNtp64(NTP_int64 *ts)
+{
+  ts->hi = ts->lo = htonl(0);
+}
+
+/* ================================================== */
+
+int
+UTI_IsZeroNtp64(const NTP_int64 *ts)
+{
+  return !ts->hi && !ts->lo;
+}
+
+/* ================================================== */
+
+int
+UTI_CompareNtp64(const NTP_int64 *a, const NTP_int64 *b)
+{
+  int32_t diff;
+
+  if (a->hi == b->hi && a->lo == b->lo)
+    return 0;
+
+  diff = ntohl(a->hi) - ntohl(b->hi);
+
+  if (diff < 0)
+    return -1;
+  if (diff > 0)
+    return 1;
+
+  return ntohl(a->lo) < ntohl(b->lo) ? -1 : 1;
+}
+
+/* ================================================== */
+
+int
+UTI_IsEqualAnyNtp64(const NTP_int64 *a, const NTP_int64 *b1, const NTP_int64 *b2,
+                    const NTP_int64 *b3)
+{
+  if (b1 && a->lo == b1->lo && a->hi == b1->hi)
+    return 1;
+
+  if (b2 && a->lo == b2->lo && a->hi == b2->hi)
+    return 1;
+
+  if (b3 && a->lo == b3->lo && a->hi == b3->hi)
+    return 1;
+
+  return 0;
+}
+
+/* ================================================== */
+
+/* Seconds part of NTP timestamp correponding to the origin of the time_t format */
+#define JAN_1970 0x83aa7e80UL
+
+#define NSEC_PER_NTP64 4.294967296
+
+void
+UTI_TimespecToNtp64(const struct timespec *src, NTP_int64 *dest, const NTP_int64 *fuzz)
+{
+  uint32_t hi, lo, sec, nsec;
+
+  sec = (uint32_t)src->tv_sec;
+  nsec = (uint32_t)src->tv_nsec;
+
+  /* Recognize zero as a special case - it always signifies
+     an 'unknown' value */
+  if (!nsec && !sec) {
+    hi = lo = 0;
+  } else {
+    hi = htonl(sec + JAN_1970);
+    lo = htonl(NSEC_PER_NTP64 * nsec);
+
+    /* Add the fuzz */
+    if (fuzz) {
+      hi ^= fuzz->hi;
+      lo ^= fuzz->lo;
+    }
+  }
+
+  dest->hi = hi;
+  dest->lo = lo;
+}
+
+/* ================================================== */
+
+void
+UTI_Ntp64ToTimespec(const NTP_int64 *src, struct timespec *dest)
+{
+  uint32_t ntp_sec, ntp_frac;
+
+  /* Zero is a special value */
+  if (UTI_IsZeroNtp64(src)) {
+    UTI_ZeroTimespec(dest);
+    return;
+  }
+
+  ntp_sec = ntohl(src->hi);
+  ntp_frac = ntohl(src->lo);
+
+#ifdef HAVE_LONG_TIME_T
+  dest->tv_sec = ntp_sec - (uint32_t)(NTP_ERA_SPLIT + JAN_1970) +
+                 (time_t)NTP_ERA_SPLIT;
+#else
+  dest->tv_sec = ntp_sec - JAN_1970;
+#endif
+
+  dest->tv_nsec = ntp_frac / NSEC_PER_NTP64;
+}
+
+/* ================================================== */
+
+double
+UTI_DiffNtp64ToDouble(const NTP_int64 *a, const NTP_int64 *b)
+{
+  /* Don't convert to timespec to allow any epoch */
+  return (int32_t)(ntohl(a->hi) - ntohl(b->hi)) +
+         ((double)ntohl(a->lo) - (double)ntohl(b->lo)) / (1.0e9 * NSEC_PER_NTP64);
+}
+
+/* ================================================== */
+
+/* Maximum offset between two sane times */
+#define MAX_OFFSET 4294967296.0
+
+/* Minimum allowed distance from maximum 32-bit time_t */
+#define MIN_ENDOFTIME_DISTANCE (365 * 24 * 3600)
+
+int
+UTI_IsTimeOffsetSane(const struct timespec *ts, double offset)
+{
+  double t;
+
+  /* Handle nan correctly here */
+  if (!(offset > -MAX_OFFSET && offset < MAX_OFFSET))
+    return 0;
+
+  t = UTI_TimespecToDouble(ts) + offset;
+
+  /* Time before 1970 is not considered valid */
+  if (t < 0.0)
+    return 0;
+
+#ifdef HAVE_LONG_TIME_T
+  /* Check if it's in the interval to which NTP time is mapped */
+  if (t < (double)NTP_ERA_SPLIT || t > (double)(NTP_ERA_SPLIT + (1LL << 32)))
+    return 0;
+#else
+  /* Don't get too close to 32-bit time_t overflow */
+  if (t > (double)(0x7fffffff - MIN_ENDOFTIME_DISTANCE))
+    return 0;
+#endif
+
+  return 1;
+}
+
+/* ================================================== */
+
+double
+UTI_Log2ToDouble(int l)
+{
+  if (l >= 0) {
+    if (l > 31)
+      l = 31;
+    return (uint32_t)1 << l;
+  } else {
+    if (l < -31)
+      l = -31;
+    return 1.0 / ((uint32_t)1 << -l);
+  }
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecNetworkToHost(const Timespec *src, struct timespec *dest)
+{
+  uint32_t sec_low, nsec;
+#ifdef HAVE_LONG_TIME_T
+  uint32_t sec_high;
+#endif
+
+  sec_low = ntohl(src->tv_sec_low);
+#ifdef HAVE_LONG_TIME_T
+  sec_high = ntohl(src->tv_sec_high);
+  if (sec_high == TV_NOHIGHSEC)
+    sec_high = 0;
+
+  dest->tv_sec = (uint64_t)sec_high << 32 | sec_low;
+#else
+  dest->tv_sec = sec_low;
+#endif
+
+  nsec = ntohl(src->tv_nsec);
+  dest->tv_nsec = MIN(nsec, 999999999U);
+}
+
+/* ================================================== */
+
+void
+UTI_TimespecHostToNetwork(const struct timespec *src, Timespec *dest)
+{
+  dest->tv_nsec = htonl(src->tv_nsec);
+#ifdef HAVE_LONG_TIME_T
+  dest->tv_sec_high = htonl((uint64_t)src->tv_sec >> 32);
+#else
+  dest->tv_sec_high = htonl(TV_NOHIGHSEC);
+#endif
+  dest->tv_sec_low = htonl(src->tv_sec);
+}
+
+/* ================================================== */
+
+uint64_t
+UTI_Integer64NetworkToHost(Integer64 i)
+{
+  return (uint64_t)ntohl(i.high) << 32 | ntohl(i.low);
+}
+
+/* ================================================== */
+
+Integer64
+UTI_Integer64HostToNetwork(uint64_t i)
+{
+  Integer64 r;
+  r.high = htonl(i >> 32);
+  r.low = htonl(i);
+  return r;
+}
+
+/* ================================================== */
+
+#define FLOAT_EXP_BITS 7
+#define FLOAT_EXP_MIN (-(1 << (FLOAT_EXP_BITS - 1)))
+#define FLOAT_EXP_MAX (-FLOAT_EXP_MIN - 1)
+#define FLOAT_COEF_BITS ((int)sizeof (int32_t) * 8 - FLOAT_EXP_BITS)
+#define FLOAT_COEF_MIN (-(1 << (FLOAT_COEF_BITS - 1)))
+#define FLOAT_COEF_MAX (-FLOAT_COEF_MIN - 1)
+
+double
+UTI_FloatNetworkToHost(Float f)
+{
+  int32_t exp, coef;
+  uint32_t x;
+
+  x = ntohl(f.f);
+
+  exp = x >> FLOAT_COEF_BITS;
+  if (exp >= 1 << (FLOAT_EXP_BITS - 1))
+      exp -= 1 << FLOAT_EXP_BITS;
+  exp -= FLOAT_COEF_BITS;
+
+  coef = x % (1U << FLOAT_COEF_BITS);
+  if (coef >= 1 << (FLOAT_COEF_BITS - 1))
+      coef -= 1 << FLOAT_COEF_BITS;
+
+  return coef * pow(2.0, exp);
+}
+
+Float
+UTI_FloatHostToNetwork(double x)
+{
+  int32_t exp, coef, neg;
+  Float f;
+
+  if (x < 0.0) {
+    x = -x;
+    neg = 1;
+  } else if (x >= 0.0) {
+    neg = 0;
+  } else {
+    /* Save NaN as zero */
+    x = 0.0;
+    neg = 0;
+  }
+
+  if (x < 1.0e-100) {
+    exp = coef = 0;
+  } else if (x > 1.0e100) {
+    exp = FLOAT_EXP_MAX;
+    coef = FLOAT_COEF_MAX + neg;
+  } else {
+    exp = log(x) / log(2) + 1;
+    coef = x * pow(2.0, -exp + FLOAT_COEF_BITS) + 0.5;
+
+    assert(coef > 0);
+
+    /* we may need to shift up to two bits down */
+    while (coef > FLOAT_COEF_MAX + neg) {
+      coef >>= 1;
+      exp++;
+    }
+
+    if (exp > FLOAT_EXP_MAX) {
+      /* overflow */
+      exp = FLOAT_EXP_MAX;
+      coef = FLOAT_COEF_MAX + neg;
+    } else if (exp < FLOAT_EXP_MIN) {
+      /* underflow */
+      if (exp + FLOAT_COEF_BITS >= FLOAT_EXP_MIN) {
+        coef >>= FLOAT_EXP_MIN - exp;
+        exp = FLOAT_EXP_MIN;
+      } else {
+        exp = coef = 0;
+      }
+    }
+  }
+
+  /* negate back */
+  if (neg)
+    coef = (uint32_t)-coef << FLOAT_EXP_BITS >> FLOAT_EXP_BITS;
+
+  f.f = htonl((uint32_t)exp << FLOAT_COEF_BITS | coef);
+  return f;
+}
+
+/* ================================================== */
+
+CMC_Algorithm
+UTI_CmacNameToAlgorithm(const char *name)
+{
+  if (strcmp(name, "AES128") == 0)
+    return CMC_AES128;
+  else if (strcmp(name, "AES256") == 0)
+    return CMC_AES256;
+  return CMC_INVALID;
+}
+
+/* ================================================== */
+
+HSH_Algorithm
+UTI_HashNameToAlgorithm(const char *name)
+{
+  if (strcmp(name, "MD5") == 0)
+    return HSH_MD5;
+  else if (strcmp(name, "SHA1") == 0)
+    return HSH_SHA1;
+  else if (strcmp(name, "SHA256") == 0)
+    return HSH_SHA256;
+  else if (strcmp(name, "SHA384") == 0)
+    return HSH_SHA384;
+  else if (strcmp(name, "SHA512") == 0)
+    return HSH_SHA512;
+  else if (strcmp(name, "SHA3-224") == 0)
+    return HSH_SHA3_224;
+  else if (strcmp(name, "SHA3-256") == 0)
+    return HSH_SHA3_256;
+  else if (strcmp(name, "SHA3-384") == 0)
+    return HSH_SHA3_384;
+  else if (strcmp(name, "SHA3-512") == 0)
+    return HSH_SHA3_512;
+  else if (strcmp(name, "TIGER") == 0)
+    return HSH_TIGER;
+  else if (strcmp(name, "WHIRLPOOL") == 0)
+    return HSH_WHIRLPOOL;
+  return HSH_INVALID;
+}
+
+/* ================================================== */
+
+int
+UTI_FdSetCloexec(int fd)
+{
+  int flags;
+
+  flags = fcntl(fd, F_GETFD);
+  if (flags == -1) {
+    DEBUG_LOG("fcntl() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  flags |= FD_CLOEXEC;
+
+  if (fcntl(fd, F_SETFD, flags) < 0) {
+    DEBUG_LOG("fcntl() failed : %s", strerror(errno));
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+UTI_SetQuitSignalsHandler(void (*handler)(int), int ignore_sigpipe)
+{
+  struct sigaction sa;
+
+  sa.sa_handler = handler;
+  sa.sa_flags = SA_RESTART;
+  if (sigemptyset(&sa.sa_mask) < 0)
+    LOG_FATAL("sigemptyset() failed");
+
+#ifdef SIGINT
+  if (sigaction(SIGINT, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGINT);
+#endif
+#ifdef SIGTERM
+  if (sigaction(SIGTERM, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGTERM);
+#endif
+#ifdef SIGQUIT
+  if (sigaction(SIGQUIT, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGQUIT);
+#endif
+#ifdef SIGHUP
+  if (sigaction(SIGHUP, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGHUP);
+#endif
+
+  if (ignore_sigpipe)
+    sa.sa_handler = SIG_IGN;
+
+  if (sigaction(SIGPIPE, &sa, NULL) < 0)
+    LOG_FATAL("sigaction(%d) failed", SIGPIPE);
+}
+
+/* ================================================== */
+
+char *
+UTI_PathToDir(const char *path)
+{
+  char *dir, *slash;
+  size_t dir_len;
+
+  slash = strrchr(path, '/');
+
+  if (!slash)
+    return Strdup(".");
+
+  if (slash == path)
+    return Strdup("/");
+
+  dir_len = slash - path;
+
+  dir = Malloc(dir_len + 1);
+  memcpy(dir, path, dir_len);
+  dir[dir_len] = '\0';
+
+  return dir;
+}
+
+/* ================================================== */
+
+static int
+create_dir(char *p, mode_t mode, uid_t uid, gid_t gid)
+{
+  int status;
+  struct stat buf;
+
+  /* See if directory exists */
+  status = stat(p, &buf);
+
+  if (status < 0) {
+    if (errno != ENOENT) {
+      LOG(LOGS_ERR, "Could not access %s : %s", p, strerror(errno));
+      return 0;
+    }
+  } else {
+    if (S_ISDIR(buf.st_mode))
+      return 1;
+    LOG(LOGS_ERR, "%s is not directory", p);
+    return 0;
+  }
+
+  /* Create the directory */
+  if (mkdir(p, mode) < 0) {
+    LOG(LOGS_ERR, "Could not create directory %s : %s", p, strerror(errno));
+    return 0;
+  }
+
+  /* Set its owner */
+  if (chown(p, uid, gid) < 0) {
+    LOG(LOGS_ERR, "Could not change ownership of %s : %s", p, strerror(errno));
+    /* Don't leave it there with incorrect ownership */
+    rmdir(p);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+/* Return 0 if the directory couldn't be created, 1 if it could (or
+   already existed) */
+int
+UTI_CreateDirAndParents(const char *path, mode_t mode, uid_t uid, gid_t gid)
+{
+  char *p;
+  int i, j, k, last;
+
+  /* Don't try to create current directory */
+  if (!strcmp(path, "."))
+    return 1;
+
+  p = (char *)Malloc(1 + strlen(path));
+
+  i = k = 0;
+  while (1) {
+    p[i++] = path[k++];
+
+    if (path[k] == '/' || !path[k]) {
+      /* Check whether its end of string, a trailing / or group of / */
+      last = 1;
+      j = k;
+      while (path[j]) {
+        if (path[j] != '/') {
+          /* Pick up a / into p[] thru the assignment at the top of the loop */
+          k = j - 1;
+          last = 0;
+          break;
+        }
+        j++;
+      }
+
+      p[i] = 0;
+
+      if (!create_dir(p, last ? mode : 0755, last ? uid : 0, last ? gid : 0)) {
+        Free(p);
+        return 0;
+      }
+
+      if (last)
+        break;
+    }
+
+    if (!path[k])
+      break;
+  }
+
+  Free(p);
+  return 1;
+}
+
+/* ================================================== */
+
+int
+UTI_CheckDirPermissions(const char *path, mode_t perm, uid_t uid, gid_t gid)
+{
+  struct stat buf;
+
+  if (stat(path, &buf)) {
+    LOG(LOGS_ERR, "Could not access %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  if (!S_ISDIR(buf.st_mode)) {
+    LOG(LOGS_ERR, "%s is not directory", path);
+    return 0;
+  }
+
+  if ((buf.st_mode & 0777) & ~perm) {
+    LOG(LOGS_ERR, "Wrong permissions on %s", path);
+    return 0;
+  }
+
+  if (buf.st_uid != uid) {
+    LOG(LOGS_ERR, "Wrong owner of %s (%s != %u)", path, "UID", uid);
+    return 0;
+  }
+
+  if (buf.st_gid != gid) {
+    LOG(LOGS_ERR, "Wrong owner of %s (%s != %u)", path, "GID", gid);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+UTI_CheckFilePermissions(const char *path, mode_t perm)
+{
+  mode_t extra_perm;
+  struct stat buf;
+
+  if (stat(path, &buf) < 0 || !S_ISREG(buf.st_mode)) {
+    /* Not considered an error */
+    return 1;
+  }
+
+  extra_perm = (buf.st_mode & 0777) & ~perm;
+  if (extra_perm != 0) {
+    LOG(LOGS_WARN, "%s permissions on %s", extra_perm & 0006 ?
+        (extra_perm & 0004 ? "World-readable" : "World-writable") : "Wrong", path);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+UTI_CheckReadOnlyAccess(const char *path)
+{
+  if (access(path, R_OK) != 0 && errno != ENOENT)
+    LOG(LOGS_WARN, "Missing read access to %s : %s", path, strerror(errno));
+  if (access(path, W_OK) == 0)
+    LOG(LOGS_WARN, "Having write access to %s", path);
+}
+
+/* ================================================== */
+
+static int
+join_path(const char *basedir, const char *name, const char *suffix,
+          char *buffer, size_t length, LOG_Severity severity)
+{
+  const char *sep;
+
+  if (!basedir) {
+    basedir = "";
+    sep = "";
+  } else {
+    sep = "/";
+  }
+
+  if (!suffix)
+    suffix = "";
+
+  if (snprintf(buffer, length, "%s%s%s%s", basedir, sep, name, suffix) >= length) {
+    LOG(severity, "File path %s%s%s%s too long", basedir, sep, name, suffix);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+FILE *
+UTI_OpenFile(const char *basedir, const char *name, const char *suffix,
+             char mode, mode_t perm)
+{
+  const char *file_mode;
+  char path[PATH_MAX];
+  LOG_Severity severity;
+  int fd, flags;
+  FILE *file;
+
+  severity = mode >= 'A' && mode <= 'Z' ? LOGS_FATAL : LOGS_ERR;
+
+  if (!join_path(basedir, name, suffix, path, sizeof (path), severity))
+    return NULL;
+
+  switch (mode) {
+    case 'r':
+    case 'R':
+      flags = O_RDONLY;
+      file_mode = "r";
+      if (severity != LOGS_FATAL)
+        severity = LOGS_DEBUG;
+      break;
+    case 'w':
+    case 'W':
+      flags = O_WRONLY | O_CREAT | O_EXCL;
+      file_mode = "w";
+      break;
+    case 'a':
+    case 'A':
+      flags = O_WRONLY | O_CREAT | O_APPEND | O_NOFOLLOW;
+      file_mode = "a";
+      break;
+    default:
+      assert(0);
+      return NULL;
+  }
+
+try_again:
+  fd = open(path, flags, perm);
+  if (fd < 0) {
+    if (errno == EEXIST) {
+      if (unlink(path) < 0) {
+        LOG(severity, "Could not remove %s : %s", path, strerror(errno));
+        return NULL;
+      }
+      DEBUG_LOG("Removed %s", path);
+      goto try_again;
+    }
+    LOG(severity, "Could not open %s : %s", path, strerror(errno));
+    return NULL;
+  }
+
+  UTI_FdSetCloexec(fd);
+
+  file = fdopen(fd, file_mode);
+  if (!file) {
+    LOG(severity, "Could not open %s : %s", path, strerror(errno));
+    close(fd);
+    return NULL;
+  }
+
+  DEBUG_LOG("Opened %s fd=%d mode=%c", path, fd, mode);
+
+  return file;
+}
+
+/* ================================================== */
+
+int
+UTI_RenameTempFile(const char *basedir, const char *name,
+                   const char *old_suffix, const char *new_suffix)
+{
+  char old_path[PATH_MAX], new_path[PATH_MAX];
+
+  if (!join_path(basedir, name, old_suffix, old_path, sizeof (old_path), LOGS_ERR))
+    return 0;
+
+  if (!join_path(basedir, name, new_suffix, new_path, sizeof (new_path), LOGS_ERR))
+    goto error;
+
+  if (rename(old_path, new_path) < 0) {
+    LOG(LOGS_ERR, "Could not replace %s with %s : %s", new_path, old_path, strerror(errno));
+    goto error;
+  }
+
+  DEBUG_LOG("Renamed %s to %s", old_path, new_path);
+
+  return 1;
+
+error:
+  if (unlink(old_path) < 0)
+    LOG(LOGS_ERR, "Could not remove %s : %s", old_path, strerror(errno));
+
+  return 0;
+}
+
+/* ================================================== */
+
+int
+UTI_RemoveFile(const char *basedir, const char *name, const char *suffix)
+{
+  char path[PATH_MAX];
+  struct stat buf;
+
+  if (!join_path(basedir, name, suffix, path, sizeof (path), LOGS_ERR))
+    return 0;
+
+  /* Avoid logging an error message if the file is not accessible */
+  if (stat(path, &buf) < 0) {
+    DEBUG_LOG("Could not remove %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  if (unlink(path) < 0) {
+    LOG(LOGS_ERR, "Could not remove %s : %s", path, strerror(errno));
+    return 0;
+  }
+
+  DEBUG_LOG("Removed %s", path);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+UTI_DropRoot(uid_t uid, gid_t gid)
+{
+  /* Drop supplementary groups */
+  if (setgroups(0, NULL))
+    LOG_FATAL("setgroups() failed : %s", strerror(errno));
+
+  /* Set effective, saved and real group ID */
+  if (setgid(gid))
+    LOG_FATAL("setgid(%u) failed : %s", gid, strerror(errno));
+
+  /* Set effective, saved and real user ID */
+  if (setuid(uid))
+    LOG_FATAL("setuid(%u) failed : %s", uid, strerror(errno));
+
+  DEBUG_LOG("Dropped root privileges: UID %u GID %u", uid, gid);
+}
+
+/* ================================================== */
+
+#define DEV_URANDOM "/dev/urandom"
+
+static FILE *urandom_file = NULL;
+
+void
+UTI_GetRandomBytesUrandom(void *buf, unsigned int len)
+{
+  if (!urandom_file)
+    urandom_file = UTI_OpenFile(NULL, DEV_URANDOM, NULL, 'R', 0);
+  if (fread(buf, 1, len, urandom_file) != len)
+    LOG_FATAL("Can't read from %s", DEV_URANDOM);
+}
+
+/* ================================================== */
+
+#ifdef HAVE_GETRANDOM
+
+static unsigned int getrandom_buf_available = 0;
+
+static void
+get_random_bytes_getrandom(char *buf, unsigned int len)
+{
+  static char rand_buf[256];
+  static unsigned int disabled = 0;
+  unsigned int i;
+
+  for (i = 0; i < len; i++) {
+    if (getrandom_buf_available == 0) {
+      if (disabled)
+        break;
+
+      if (getrandom(rand_buf, sizeof (rand_buf), GRND_NONBLOCK) != sizeof (rand_buf)) {
+        disabled = 1;
+        break;
+      }
+
+      getrandom_buf_available = sizeof (rand_buf);
+    }
+
+    buf[i] = rand_buf[--getrandom_buf_available];
+  }
+
+  if (i < len)
+    UTI_GetRandomBytesUrandom(buf, len);
+}
+#endif
+
+/* ================================================== */
+
+void
+UTI_GetRandomBytes(void *buf, unsigned int len)
+{
+#ifdef HAVE_ARC4RANDOM
+  arc4random_buf(buf, len);
+#elif defined(HAVE_GETRANDOM)
+  get_random_bytes_getrandom(buf, len);
+#else
+  UTI_GetRandomBytesUrandom(buf, len);
+#endif
+}
+
+/* ================================================== */
+
+void
+UTI_ResetGetRandomFunctions(void)
+{
+  if (urandom_file) {
+    fclose(urandom_file);
+    urandom_file = NULL;
+  }
+#ifdef HAVE_GETRANDOM
+  getrandom_buf_available = 0;
+#endif
+}
+
+/* ================================================== */
+
+int
+UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len)
+{
+  unsigned int i, l;
+
+  if (hex_len < 1)
+    return 0;
+
+  hex[0] = '\0';
+
+  for (i = l = 0; i < buf_len; i++, l += 2) {
+    if (l + 2 >= hex_len ||
+        snprintf(hex + l, hex_len - l, "%02hhX", ((const char *)buf)[i]) != 2)
+      return 0;
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
+unsigned int
+UTI_HexToBytes(const char *hex, void *buf, unsigned int len)
+{
+  char *p, byte[3];
+  unsigned int i;
+
+  for (i = 0; i < len && *hex != '\0'; i++) {
+    byte[0] = *hex++;
+    if (*hex == '\0')
+      return 0;
+    byte[1] = *hex++;
+    byte[2] = '\0';
+    ((char *)buf)[i] = strtol(byte, &p, 16);
+
+    if (p != byte + 2)
+      return 0;
+  }
+
+  return *hex == '\0' ? i : 0;
+}
+
+/* ================================================== */
+
+int
+UTI_SplitString(char *string, char **words, int max_saved_words)
+{
+  char *s = string;
+  int i;
+
+  for (i = 0; i < max_saved_words; i++)
+    words[i] = NULL;
+
+  for (i = 0; ; i++) {
+    /* Zero white-space characters before the word */
+    while (*s != '\0' && isspace((unsigned char)*s))
+      *s++ = '\0';
+
+    if (*s == '\0')
+      break;
+
+    if (i < max_saved_words)
+      words[i] = s;
+
+    /* Find the next word */
+    while (*s != '\0' && !isspace((unsigned char)*s))
+      s++;
+  }
+
+  return i;
+}
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..d38abf0
--- /dev/null
+++ b/util.h
@@ -0,0 +1,271 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2003
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Various utility functions
+  */
+
+#ifndef GOT_UTIL_H
+#define GOT_UTIL_H
+
+#include "sysincl.h"
+
+#include "addressing.h"
+#include "ntp.h"
+#include "candm.h"
+#include "cmac.h"
+#include "hash.h"
+
+/* Zero a timespec */
+extern void UTI_ZeroTimespec(struct timespec *ts);
+
+/* Check if a timespec is zero */
+extern int UTI_IsZeroTimespec(struct timespec *ts);
+
+/* Convert a timeval into a timespec */
+extern void UTI_TimevalToTimespec(const struct timeval *tv, struct timespec *ts);
+
+/* Convert a timespec into a timeval */
+extern void UTI_TimespecToTimeval(const struct timespec *ts, struct timeval *tv);
+
+/* Convert a timespec into a floating point number of seconds */
+extern double UTI_TimespecToDouble(const struct timespec *ts);
+
+/* Convert a number of seconds expressed in floating point into a
+   timespec */
+extern void UTI_DoubleToTimespec(double d, struct timespec *ts);
+
+/* Normalise a timespec, by adding or subtracting seconds to bring
+   its nanosecond field into range */
+extern void UTI_NormaliseTimespec(struct timespec *ts);
+
+/* Convert a timeval into a floating point number of seconds */
+extern double UTI_TimevalToDouble(const struct timeval *tv);
+
+/* Convert a number of seconds expressed in floating point into a
+   timeval */
+extern void UTI_DoubleToTimeval(double a, struct timeval *b);
+
+/* Normalise a struct timeval, by adding or subtracting seconds to bring
+   its microseconds field into range */
+extern void UTI_NormaliseTimeval(struct timeval *x);
+
+/* Returns -1 if a comes earlier than b, 0 if a is the same time as b,
+   and +1 if a comes after b */
+extern int UTI_CompareTimespecs(const struct timespec *a, const struct timespec *b);
+
+/* Calculate result = a - b */
+extern void UTI_DiffTimespecs(struct timespec *result,
+                              const struct timespec *a, const struct timespec *b);
+
+/* Calculate result = a - b and return as a double */
+extern double UTI_DiffTimespecsToDouble(const struct timespec *a, const struct timespec *b);
+
+/* Add a double increment to a timespec to get a new one. 'start' is
+   the starting time, 'end' is the result that we return.  This is
+   safe to use if start and end are the same */
+extern void UTI_AddDoubleToTimespec(const struct timespec *start, double increment,
+                                    struct timespec *end);
+
+/* Calculate the average and difference (as a double) of two timespecs */
+extern void UTI_AverageDiffTimespecs(const struct timespec *earlier, const struct timespec *later,
+                                     struct timespec *average, double *diff);
+
+/* Calculate result = a - b + c */
+extern void UTI_AddDiffToTimespec(const struct timespec *a, const struct timespec *b,
+                                  const struct timespec *c, struct timespec *result);
+
+/* Convert a timespec into a temporary string, largely for diagnostic
+   display */
+extern char *UTI_TimespecToString(const struct timespec *ts);
+
+/* Convert an NTP timestamp into a temporary string, largely for
+   diagnostic display */
+extern char *UTI_Ntp64ToString(const NTP_int64 *ts);
+
+/* Convert ref_id into a temporary string, for diagnostics */
+extern char *UTI_RefidToString(uint32_t ref_id);
+
+/* Convert an IP address to string, for diagnostics */
+extern char *UTI_IPToString(const IPAddr *ip);
+
+extern int UTI_StringToIP(const char *addr, IPAddr *ip);
+extern int UTI_IsStringIP(const char *string);
+extern int UTI_StringToIdIP(const char *addr, IPAddr *ip);
+extern int UTI_IsIPReal(const IPAddr *ip);
+extern uint32_t UTI_IPToRefid(const IPAddr *ip);
+extern uint32_t UTI_IPToHash(const IPAddr *ip);
+extern void UTI_IPHostToNetwork(const IPAddr *src, IPAddr *dest);
+extern void UTI_IPNetworkToHost(const IPAddr *src, IPAddr *dest);
+extern int UTI_CompareIPs(const IPAddr *a, const IPAddr *b, const IPAddr *mask);
+
+extern char *UTI_IPSockAddrToString(const IPSockAddr *sa);
+
+extern char *UTI_IPSubnetToString(IPAddr *subnet, int bits);
+
+extern char *UTI_TimeToLogForm(time_t t);
+
+/* Adjust time following a frequency/offset change */
+extern void UTI_AdjustTimespec(const struct timespec *old_ts, const struct timespec *when,
+                               struct timespec *new_ts, double *delta_time,
+                               double dfreq, double doffset);
+
+/* Get zero NTP timestamp with random bits below precision */
+extern void UTI_GetNtp64Fuzz(NTP_int64 *ts, int precision);
+
+extern double UTI_Ntp32ToDouble(NTP_int32 x);
+extern NTP_int32 UTI_DoubleToNtp32(double x);
+
+extern double UTI_Ntp32f28ToDouble(NTP_int32 x);
+extern NTP_int32 UTI_DoubleToNtp32f28(double x);
+
+/* Zero an NTP timestamp */
+extern void UTI_ZeroNtp64(NTP_int64 *ts);
+
+/* Check if an NTP timestamp is zero */
+extern int UTI_IsZeroNtp64(const NTP_int64 *ts);
+
+/* Compare two NTP timestamps.  Returns -1 if a is before b, 0 if a is equal to
+   b, and 1 if a is after b. */
+extern int UTI_CompareNtp64(const NTP_int64 *a, const NTP_int64 *b);
+
+/* Compare an NTP timestamp with up to three other timestamps.  Returns 0
+   if a is not equal to any of b1, b2, and b3, 1 otherwise. */
+extern int UTI_IsEqualAnyNtp64(const NTP_int64 *a, const NTP_int64 *b1,
+                               const NTP_int64 *b2, const NTP_int64 *b3);
+
+/* Convert a timespec into an NTP timestamp */
+extern void UTI_TimespecToNtp64(const struct timespec *src, NTP_int64 *dest,
+                                const NTP_int64 *fuzz);
+
+/* Convert an NTP timestamp into a timespec */
+extern void UTI_Ntp64ToTimespec(const NTP_int64 *src, struct timespec *dest);
+
+/* Calculate a - b in any epoch */
+extern double UTI_DiffNtp64ToDouble(const NTP_int64 *a, const NTP_int64 *b);
+
+/* Check if time + offset is sane */
+extern int UTI_IsTimeOffsetSane(const struct timespec *ts, double offset);
+
+/* Get 2 raised to power of a signed integer */
+extern double UTI_Log2ToDouble(int l);
+
+extern void UTI_TimespecNetworkToHost(const Timespec *src, struct timespec *dest);
+extern void UTI_TimespecHostToNetwork(const struct timespec *src, Timespec *dest);
+
+uint64_t UTI_Integer64NetworkToHost(Integer64 i);
+Integer64 UTI_Integer64HostToNetwork(uint64_t i);
+
+extern double UTI_FloatNetworkToHost(Float x);
+extern Float UTI_FloatHostToNetwork(double x);
+
+extern CMC_Algorithm UTI_CmacNameToAlgorithm(const char *name);
+extern HSH_Algorithm UTI_HashNameToAlgorithm(const char *name);
+
+/* Set FD_CLOEXEC on descriptor */
+extern int UTI_FdSetCloexec(int fd);
+
+extern void UTI_SetQuitSignalsHandler(void (*handler)(int), int ignore_sigpipe);
+
+/* Get directory (as an allocated string) for a path */
+extern char *UTI_PathToDir(const char *path);
+
+/* Create a directory with a specified mode (umasked) and set its uid/gid.
+   Create also any parent directories that don't exist with mode 755 and
+   default uid/gid.  Returns 1 if created or already exists (even with
+   different mode/uid/gid), 0 otherwise. */
+extern int UTI_CreateDirAndParents(const char *path, mode_t mode, uid_t uid, gid_t gid);
+
+/* Check if a directory is secure.  It must not have other than the specified
+   permissions and its uid/gid must match the specified values. */
+extern int UTI_CheckDirPermissions(const char *path, mode_t perm, uid_t uid, gid_t gid);
+
+/* Check and log a warning message if a file has more permissions than
+   specified.  It does not return error if it is not an accessible file. */
+extern int UTI_CheckFilePermissions(const char *path, mode_t perm);
+
+/* Log a warning message if not having read access or having write access
+   to a file/directory */
+extern void UTI_CheckReadOnlyAccess(const char *path);
+
+/* Open a file.  The full path of the file is constructed from the basedir
+   (may be NULL), '/' (if basedir is not NULL), name, and suffix (may be NULL).
+   Created files have specified permissions (umasked).  Returns NULL on error.
+   The following modes are supported (if the mode is an uppercase character,
+   errors are fatal):
+   r/R - open an existing file for reading
+   w/W - open a new file for writing (remove existing file)
+   a/A - open an existing file for appending (create if does not exist) */
+extern FILE *UTI_OpenFile(const char *basedir, const char *name, const char *suffix,
+                          char mode, mode_t perm);
+
+/* Rename a temporary file by changing its suffix.  The paths are constructed as
+   in UTI_OpenFile().  If the renaming fails, the file will be removed. */
+extern int UTI_RenameTempFile(const char *basedir, const char *name,
+                              const char *old_suffix, const char *new_suffix);
+
+/* Remove a file.  The path is constructed as in UTI_OpenFile(). */
+extern int UTI_RemoveFile(const char *basedir, const char *name, const char *suffix);
+
+/* Set process user/group IDs and drop supplementary groups */
+extern void UTI_DropRoot(uid_t uid, gid_t gid);
+
+/* Fill buffer with random bytes from /dev/urandom */
+extern void UTI_GetRandomBytesUrandom(void *buf, unsigned int len);
+
+/* Fill buffer with random bytes from /dev/urandom or a faster source if it's
+   available (e.g. arc4random()), which may not necessarily be suitable for
+   generating long-term keys */
+extern void UTI_GetRandomBytes(void *buf, unsigned int len);
+
+/* Close /dev/urandom and drop any cached data used by the GetRandom functions
+   to prevent forked processes getting the same sequence of random numbers */
+extern void UTI_ResetGetRandomFunctions(void);
+
+/* Print data in hexadecimal format */
+extern int UTI_BytesToHex(const void *buf, unsigned int buf_len, char *hex, unsigned int hex_len);
+
+/* Parse a string containing data in hexadecimal format.  In-place conversion
+   is supported. */
+extern unsigned int UTI_HexToBytes(const char *hex, void *buf, unsigned int len);
+
+/* Split a string into words separated by whitespace characters.  It returns
+   the number of words found in the string, but saves only up to the specified
+   number of pointers to the words. */
+extern int UTI_SplitString(char *string, char **words, int max_saved_words);
+
+/* Macros to get maximum and minimum of two values */
+#ifdef MAX
+#undef MAX
+#endif
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+#ifdef MIN
+#undef MIN
+#endif
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+
+/* Macro to clamp a value between two values */
+#define CLAMP(min, x, max) (MAX((min), MIN((x), (max))))
+
+#define SQUARE(x) ((x) * (x))
+
+#endif /* GOT_UTIL_H */
diff --git a/version.txt b/version.txt
new file mode 100644
index 0000000..515be8f
--- /dev/null
+++ b/version.txt
@@ -0,0 +1 @@
+4.4
-- 
cgit v1.2.3


From 5c6b1c522db965b71c2f3646d205d4dfd15b864a Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 9 Aug 2023 17:50:42 +0200
Subject: Debianize chronyd-restricted.service

Forwarded: not-needed
Last-Update: 2023-08-09

Last-Update: 2023-08-09
Gbp-Pq: Name debianize-chronyd-restricted-unit-file.patch
---
 examples/chronyd-restricted.service | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/examples/chronyd-restricted.service b/examples/chronyd-restricted.service
index 30ba7d9..d89f9d3 100644
--- a/examples/chronyd-restricted.service
+++ b/examples/chronyd-restricted.service
@@ -14,10 +14,10 @@ ConditionCapability=CAP_SYS_TIME
 [Service]
 Type=forking
 PIDFile=/run/chrony/chronyd.pid
-EnvironmentFile=-/etc/sysconfig/chronyd
-ExecStart=/usr/sbin/chronyd -U $OPTIONS
+EnvironmentFile=-/etc/default/chrony
+ExecStart=/usr/sbin/chronyd -U $DAEMON_OPTS
 
-User=chrony
+User=_chrony
 LogsDirectory=chrony
 LogsDirectoryMode=0750
 RuntimeDirectory=chrony
-- 
cgit v1.2.3


From 77cd01702c32413316b6947e2aac1e341b504aee Mon Sep 17 00:00:00 2001
From: Vincent Blut <vincent.debian@free.fr>
Date: Wed, 9 Aug 2023 17:50:42 +0200
Subject: Move server_dir path to /run

Forwarded: no
Last-Update: 2020-09-16

Last-Update: 2020-09-16
Gbp-Pq: Name nm-dispatcher-dhcp_Move-server_dir-to-run.patch
---
 examples/chrony.nm-dispatcher.dhcp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/chrony.nm-dispatcher.dhcp b/examples/chrony.nm-dispatcher.dhcp
index 547ce83..203c102 100644
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -10,7 +10,7 @@ action=$2
 
 chronyc=/usr/bin/chronyc
 server_options=iburst
-server_dir=/var/run/chrony-dhcp
+server_dir=/run/chrony-dhcp
 
 dhcp_server_file=$server_dir/$interface.sources
 dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
-- 
cgit v1.2.3