diff options
author | Colin Watson <cjwatson@debian.org> | 2014-02-09 16:10:18 +0000 |
---|---|---|
committer | Colin Watson <cjwatson@debian.org> | 2019-10-09 23:07:49 +0100 |
commit | 7abde40896668ce9debfe056c7dabc6a70ef7da4 (patch) | |
tree | 56e57f3b57350a1a18cf9798e728af6c12d4a3c7 | |
parent | ab765b2bd55062a704f09da8f8c1c4ad1d6630a7 (diff) |
Various Debian-specific configuration changes
ssh: Enable ForwardX11Trusted, returning to earlier semantics which cause
fewer problems with existing setups (http://bugs.debian.org/237021).
ssh: Set 'SendEnv LANG LC_*' by default (http://bugs.debian.org/264024).
ssh: Enable HashKnownHosts by default to try to limit the spread of ssh
worms.
ssh: Enable GSSAPIAuthentication by default.
sshd: Enable PAM, disable ChallengeResponseAuthentication, and disable
PrintMotd.
sshd: Enable X11Forwarding.
sshd: Set 'AcceptEnv LANG LC_*' by default.
sshd: Change sftp subsystem path to /usr/lib/openssh/sftp-server.
Document all of this.
Author: Russ Allbery <rra@debian.org>
Forwarded: not-needed
Last-Update: 2017-10-04
Patch-Name: debian-config.patch
-rw-r--r-- | readconf.c | 2 | ||||
-rw-r--r-- | ssh.1 | 21 | ||||
-rw-r--r-- | ssh_config | 6 | ||||
-rw-r--r-- | ssh_config.5 | 19 | ||||
-rw-r--r-- | sshd_config | 16 | ||||
-rw-r--r-- | sshd_config.5 | 22 |
6 files changed, 77 insertions, 9 deletions
diff --git a/readconf.c b/readconf.c index 16d2729dd..253574ce0 100644 --- a/readconf.c +++ b/readconf.c @@ -2037,7 +2037,7 @@ fill_default_options(Options * options) if (options->forward_x11 == -1) options->forward_x11 = 0; if (options->forward_x11_trusted == -1) - options->forward_x11_trusted = 0; + options->forward_x11_trusted = 1; if (options->forward_x11_timeout == -1) options->forward_x11_timeout = 1200; /* @@ -795,6 +795,16 @@ directive in .Xr ssh_config 5 for more information. .Pp +(Debian-specific: X11 forwarding is not subjected to X11 SECURITY extension +restrictions by default, because too many programs currently crash in this +mode. +Set the +.Cm ForwardX11Trusted +option to +.Dq no +to restore the upstream behaviour. +This may change in future depending on client-side improvements.) +.Pp .It Fl x Disables X11 forwarding. .Pp @@ -803,6 +813,17 @@ Enables trusted X11 forwarding. Trusted X11 forwardings are not subjected to the X11 SECURITY extension controls. .Pp +(Debian-specific: This option does nothing in the default configuration: it +is equivalent to +.Dq Cm ForwardX11Trusted No yes , +which is the default as described above. +Set the +.Cm ForwardX11Trusted +option to +.Dq no +to restore the upstream behaviour. +This may change in future depending on client-side improvements.) +.Pp .It Fl y Send log information using the .Xr syslog 3 diff --git a/ssh_config b/ssh_config index 1ff999b68..6dd6ecf87 100644 --- a/ssh_config +++ b/ssh_config @@ -17,9 +17,10 @@ # list of available options, their meanings and defaults, please see the # ssh_config(5) man page. -# Host * +Host * # ForwardAgent no # ForwardX11 no +# ForwardX11Trusted yes # PasswordAuthentication yes # HostbasedAuthentication no # GSSAPIAuthentication no @@ -45,3 +46,6 @@ # VisualHostKey no # ProxyCommand ssh -q -W %h:%p gateway.example.com # RekeyLimit 1G 1h + SendEnv LANG LC_* + HashKnownHosts yes + GSSAPIAuthentication yes diff --git a/ssh_config.5 b/ssh_config.5 index 4b42aab9d..d27655e15 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -71,6 +71,22 @@ Since the first obtained value for each parameter is used, more host-specific declarations should be given near the beginning of the file, and general defaults at the end. .Pp +Note that the Debian +.Ic openssh-client +package sets several options as standard in +.Pa /etc/ssh/ssh_config +which are not the default in +.Xr ssh 1 : +.Pp +.Bl -bullet -offset indent -compact +.It +.Cm SendEnv No LANG LC_* +.It +.Cm HashKnownHosts No yes +.It +.Cm GSSAPIAuthentication No yes +.El +.Pp The file contains keyword-argument pairs, one per line. Lines starting with .Ql # @@ -721,11 +737,12 @@ elapsed. .It Cm ForwardX11Trusted If this option is set to .Cm yes , +(the Debian-specific default), remote X11 clients will have full access to the original X11 display. .Pp If this option is set to .Cm no -(the default), +(the upstream default), remote X11 clients will be considered untrusted and prevented from stealing or tampering with data belonging to trusted X11 clients. diff --git a/sshd_config b/sshd_config index 2c48105f8..ed8272f6d 100644 --- a/sshd_config +++ b/sshd_config @@ -57,8 +57,9 @@ AuthorizedKeysFile .ssh/authorized_keys #PasswordAuthentication yes #PermitEmptyPasswords no -# Change to no to disable s/key passwords -#ChallengeResponseAuthentication yes +# Change to yes to enable challenge-response passwords (beware issues with +# some PAM modules and threads) +ChallengeResponseAuthentication no # Kerberos options #KerberosAuthentication no @@ -81,16 +82,16 @@ AuthorizedKeysFile .ssh/authorized_keys # If you just want the PAM account and session checks to run without # PAM authentication, then enable this but set PasswordAuthentication # and ChallengeResponseAuthentication to 'no'. -#UsePAM no +UsePAM yes #AllowAgentForwarding yes #AllowTcpForwarding yes #GatewayPorts no -#X11Forwarding no +X11Forwarding yes #X11DisplayOffset 10 #X11UseLocalhost yes #PermitTTY yes -#PrintMotd yes +PrintMotd no #PrintLastLog yes #TCPKeepAlive yes #PermitUserEnvironment no @@ -107,8 +108,11 @@ AuthorizedKeysFile .ssh/authorized_keys # no default banner path #Banner none +# Allow client to pass locale environment variables +AcceptEnv LANG LC_* + # override default of no subsystems -Subsystem sftp /usr/libexec/sftp-server +Subsystem sftp /usr/lib/openssh/sftp-server # Example of overriding settings on a per-user basis #Match User anoncvs diff --git a/sshd_config.5 b/sshd_config.5 index 270805060..02e29cb6f 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -56,6 +56,28 @@ Arguments may optionally be enclosed in double quotes .Pq \&" in order to represent arguments containing spaces. .Pp +Note that the Debian +.Ic openssh-server +package sets several options as standard in +.Pa /etc/ssh/sshd_config +which are not the default in +.Xr sshd 8 : +.Pp +.Bl -bullet -offset indent -compact +.It +.Cm ChallengeResponseAuthentication No no +.It +.Cm X11Forwarding No yes +.It +.Cm PrintMotd No no +.It +.Cm AcceptEnv No LANG LC_* +.It +.Cm Subsystem No sftp /usr/lib/openssh/sftp-server +.It +.Cm UsePAM No yes +.El +.Pp The possible keywords and their meanings are as follows (note that keywords are case-insensitive and arguments are case-sensitive): |