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authorColin Watson <cjwatson@debian.org>2003-09-01 18:33:32 +0000
committerColin Watson <cjwatson@debian.org>2003-09-01 18:33:32 +0000
commit58bfa257481a1c6938ada9bbd38801cc45633fb0 (patch)
tree385160ff5c19376a1e1bfd34fcf5c91cff42908e /ssh.0
parentae225aa5594655e3fa5685b4dd7f2ae0e1a5e2d7 (diff)
parent58657d96514cd6f16d82add8d6f4adbb36765758 (diff)
Import OpenSSH 3.6p1.
Diffstat (limited to 'ssh.0')
-rw-r--r--ssh.0614
1 files changed, 614 insertions, 0 deletions
diff --git a/ssh.0 b/ssh.0
new file mode 100644
index 000000000..8fcd2a3d0
--- /dev/null
+++ b/ssh.0
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+SSH(1) BSD General Commands Manual SSH(1)
+
+^[[1mNAME^[[0m
+ ^[[1mssh ^[[22mM-bMM-^R OpenSSH SSH client (remote login program)
+
+^[[1mSYNOPSIS^[[0m
+ ^[[1mssh ^[[22m[^[[1mM-bMM-^Rl ^[[4m^[[22mlogin_name^[[24m] ^[[4mhostname^[[24m | ^[[4muser@hostname^[[24m [^[[4mcommand^[[24m]
+
+ ^[[1mssh ^[[22m[^[[1mM-bMM-^RafgknqstvxACNTX1246^[[22m] [^[[1mM-bMM-^Rb ^[[4m^[[22mbind_address^[[24m] [^[[1mM-bMM-^Rc ^[[4m^[[22mcipher_spec^[[24m]
+ [^[[1mM-bMM-^Re ^[[4m^[[22mescape_char^[[24m] [^[[1mM-bMM-^Ri ^[[4m^[[22midentity_file^[[24m] [^[[1mM-bMM-^Rl ^[[4m^[[22mlogin_name^[[24m] [^[[1mM-bMM-^Rm ^[[4m^[[22mmac_spec^[[24m]
+ [^[[1mM-bMM-^Ro ^[[4m^[[22moption^[[24m] [^[[1mM-bMM-^Rp ^[[4m^[[22mport^[[24m] [^[[1mM-bMM-^RF ^[[4m^[[22mconfigfile^[[24m] [^[[1mM-bMM-^RL ^[[4m^[[22mport^[[24m:^[[4mhost^[[24m:^[[4mhostport^[[24m] [^[[1mM-bMM-^RR^[[0m
+ ^[[4mport^[[24m:^[[4mhost^[[24m:^[[4mhostport^[[24m] [^[[1mM-bMM-^RD ^[[4m^[[22mport^[[24m] ^[[4mhostname^[[24m | ^[[4muser@hostname^[[24m [^[[4mcommand^[[24m]
+
+^[[1mDESCRIPTION^[[0m
+ ^[[1mssh ^[[22m(SSH client) is a program for logging into a remote machine and for
+ executing commands on a remote machine. It is intended to replace rlogin
+ and rsh, and provide secure encrypted communications between two
+ untrusted hosts over an insecure network. X11 connections and arbitrary
+ TCP/IP ports can also be forwarded over the secure channel.
+
+ ^[[1mssh ^[[22mconnects and logs into the specified ^[[4mhostname^[[24m. The user must prove
+ his/her identity to the remote machine using one of several methods
+ depending on the protocol version used:
+
+ ^[[1mSSH protocol version 1^[[0m
+
+ First, if the machine the user logs in from is listed in ^[[4m/etc/hosts.equiv^[[0m
+ or ^[[4m/etc/shosts.equiv^[[24m on the remote machine, and the user names are the
+ same on both sides, the user is immediately permitted to log in. Second,
+ if ^[[4m.rhosts^[[24m or ^[[4m.shosts^[[24m exists in the userM-bM-^@M-^Ys home directory on the remote
+ machine and contains a line containing the name of the client machine and
+ the name of the user on that machine, the user is permitted to log in.
+ This form of authentication alone is normally not allowed by the server
+ because it is not secure.
+
+ The second authentication method is the ^[[4mrhosts^[[24m or ^[[4mhosts.equiv^[[24m method comM-bM-^@M-^P
+ bined with RSAM-bM-^@M-^Pbased host authentication. It means that if the login
+ would be permitted by ^[[4m$HOME/.rhosts^[[24m, ^[[4m$HOME/.shosts^[[24m, ^[[4m/etc/hosts.equiv^[[24m, or
+ ^[[4m/etc/shosts.equiv^[[24m, and if additionally the server can verify the clientM-bM-^@M-^Ys
+ host key (see ^[[4m/etc/ssh/ssh_known_hosts^[[24m and ^[[4m$HOME/.ssh/known_hosts^[[24m in the
+ ^[[4mFILES^[[24m section), only then login is permitted. This authentication method
+ closes security holes due to IP spoofing, DNS spoofing and routing spoofM-bM-^@M-^P
+ ing. [Note to the administrator: ^[[4m/etc/hosts.equiv^[[24m, ^[[4m$HOME/.rhosts^[[24m, and
+ the rlogin/rsh protocol in general, are inherently insecure and should be
+ disabled if security is desired.]
+
+ As a third authentication method, ^[[1mssh ^[[22msupports RSA based authentication.
+ The scheme is based on publicM-bM-^@M-^Pkey cryptography: there are cryptosystems
+ where encryption and decryption are done using separate keys, and it is
+ not possible to derive the decryption key from the encryption key. RSA
+ is one such system. The idea is that each user creates a public/private
+ key pair for authentication purposes. The server knows the public key,
+ and only the user knows the private key. The file
+ ^[[4m$HOME/.ssh/authorized_keys^[[24m lists the public keys that are permitted for
+ logging in. When the user logs in, the ^[[1mssh ^[[22mprogram tells the server
+ which key pair it would like to use for authentication. The server
+ checks if this key is permitted, and if so, sends the user (actually the
+ ^[[1mssh ^[[22mprogram running on behalf of the user) a challenge, a random number,
+ encrypted by the userM-bM-^@M-^Ys public key. The challenge can only be decrypted
+ using the proper private key. The userM-bM-^@M-^Ys client then decrypts the chalM-bM-^@M-^P
+ lenge using the private key, proving that he/she knows the private key
+ but without disclosing it to the server.
+
+ ^[[1mssh ^[[22mimplements the RSA authentication protocol automatically. The user
+ creates his/her RSA key pair by running sshM-bM-^@M-^Pkeygen(1). This stores the
+ private key in ^[[4m$HOME/.ssh/identity^[[24m and the public key in
+ ^[[4m$HOME/.ssh/identity.pub^[[24m in the userM-bM-^@M-^Ys home directory. The user should
+ then copy the ^[[4midentity.pub^[[24m to ^[[4m$HOME/.ssh/authorized_keys^[[24m in his/her home
+ directory on the remote machine (the ^[[4mauthorized_keys^[[24m file corresponds to
+ the conventional ^[[4m$HOME/.rhosts^[[24m file, and has one key per line, though the
+ lines can be very long). After this, the user can log in without giving
+ the password. RSA authentication is much more secure than rhosts authenM-bM-^@M-^P
+ tication.
+
+ The most convenient way to use RSA authentication may be with an authenM-bM-^@M-^P
+ tication agent. See sshM-bM-^@M-^Pagent(1) for more information.
+
+ If other authentication methods fail, ^[[1mssh ^[[22mprompts the user for a passM-bM-^@M-^P
+ word. The password is sent to the remote host for checking; however,
+ since all communications are encrypted, the password cannot be seen by
+ someone listening on the network.
+
+ ^[[1mSSH protocol version 2^[[0m
+
+ When a user connects using protocol version 2 similar authentication
+ methods are available. Using the default values for
+ ^[[1mPreferredAuthentications^[[22m, the client will try to authenticate first using
+ the hostbased method; if this method fails public key authentication is
+ attempted, and finally if this method fails keyboardM-bM-^@M-^Pinteractive and
+ password authentication are tried.
+
+ The public key method is similar to RSA authentication described in the
+ previous section and allows the RSA or DSA algorithm to be used: The
+ client uses his private key, ^[[4m$HOME/.ssh/id_dsa^[[24m or ^[[4m$HOME/.ssh/id_rsa^[[24m, to
+ sign the session identifier and sends the result to the server. The
+ server checks whether the matching public key is listed in
+ ^[[4m$HOME/.ssh/authorized_keys^[[24m and grants access if both the key is found and
+ the signature is correct. The session identifier is derived from a
+ shared DiffieM-bM-^@M-^PHellman value and is only known to the client and the
+ server.
+
+ If public key authentication fails or is not available a password can be
+ sent encrypted to the remote host for proving the userM-bM-^@M-^Ys identity.
+
+ Additionally, ^[[1mssh ^[[22msupports hostbased or challenge response authenticaM-bM-^@M-^P
+ tion.
+
+ Protocol 2 provides additional mechanisms for confidentiality (the trafM-bM-^@M-^P
+ fic is encrypted using 3DES, Blowfish, CAST128 or Arcfour) and integrity
+ (hmacM-bM-^@M-^Pmd5, hmacM-bM-^@M-^Psha1). Note that protocol 1 lacks a strong mechanism for
+ ensuring the integrity of the connection.
+
+ ^[[1mLogin session and remote execution^[[0m
+
+ When the userM-bM-^@M-^Ys identity has been accepted by the server, the server
+ either executes the given command, or logs into the machine and gives the
+ user a normal shell on the remote machine. All communication with the
+ remote command or shell will be automatically encrypted.
+
+ If a pseudoM-bM-^@M-^Pterminal has been allocated (normal login session), the user
+ may use the escape characters noted below.
+
+ If no pseudo tty has been allocated, the session is transparent and can
+ be used to reliably transfer binary data. On most systems, setting the
+ escape character to M-bM-^@M-^\noneM-bM-^@M-^] will also make the session transparent even if
+ a tty is used.
+
+ The session terminates when the command or shell on the remote machine
+ exits and all X11 and TCP/IP connections have been closed. The exit staM-bM-^@M-^P
+ tus of the remote program is returned as the exit status of ^[[1mssh^[[22m.
+
+ ^[[1mEscape Characters^[[0m
+
+ When a pseudo terminal has been requested, ssh supports a number of funcM-bM-^@M-^P
+ tions through the use of an escape character.
+
+ A single tilde character can be sent as ^[[1m~~ ^[[22mor by following the tilde by a
+ character other than those described below. The escape character must
+ always follow a newline to be interpreted as special. The escape characM-bM-^@M-^P
+ ter can be changed in configuration files using the ^[[1mEscapeChar ^[[22mconfiguraM-bM-^@M-^P
+ tion directive or on the command line by the ^[[1mM-bMM-^Re ^[[22moption.
+
+ The supported escapes (assuming the default M-bM-^@M-^X~M-bM-^@M-^Y) are:
+
+ ^[[1m~. ^[[22mDisconnect
+
+ ^[[1m~^Z ^[[22mBackground ssh
+
+ ^[[1m~# ^[[22mList forwarded connections
+
+ ^[[1m~& ^[[22mBackground ssh at logout when waiting for forwarded connection /
+ X11 sessions to terminate
+
+ ^[[1m~? ^[[22mDisplay a list of escape characters
+
+ ^[[1m~C ^[[22mOpen command line (only useful for adding port forwardings using
+ the ^[[1mM-bMM-^RL ^[[22mand ^[[1mM-bMM-^RR ^[[22moptions)
+
+ ^[[1m~R ^[[22mRequest rekeying of the connection (only useful for SSH protocol
+ version 2 and if the peer supports it)
+
+ ^[[1mX11 and TCP forwarding^[[0m
+
+ If the ^[[1mForwardX11 ^[[22mvariable is set to M-bM-^@M-^\yesM-bM-^@M-^] (or, see the description of
+ the ^[[1mM-bMM-^RX ^[[22mand ^[[1mM-bMM-^Rx ^[[22moptions described later) and the user is using X11 (the
+ DISPLAY environment variable is set), the connection to the X11 display
+ is automatically forwarded to the remote side in such a way that any X11
+ programs started from the shell (or command) will go through the
+ encrypted channel, and the connection to the real X server will be made
+ from the local machine. The user should not manually set DISPLAY. ForM-bM-^@M-^P
+ warding of X11 connections can be configured on the command line or in
+ configuration files.
+
+ The DISPLAY value set by ^[[1mssh ^[[22mwill point to the server machine, but with a
+ display number greater than zero. This is normal, and happens because
+ ^[[1mssh ^[[22mcreates a M-bM-^@M-^\proxyM-bM-^@M-^] X server on the server machine for forwarding the
+ connections over the encrypted channel.
+
+ ^[[1mssh ^[[22mwill also automatically set up Xauthority data on the server machine.
+ For this purpose, it will generate a random authorization cookie, store
+ it in Xauthority on the server, and verify that any forwarded connections
+ carry this cookie and replace it by the real cookie when the connection
+ is opened. The real authentication cookie is never sent to the server
+ machine (and no cookies are sent in the plain).
+
+ If the ^[[1mForwardAgent ^[[22mvariable is set to M-bM-^@M-^\yesM-bM-^@M-^] (or, see the description of
+ the ^[[1mM-bMM-^RA ^[[22mand ^[[1mM-bMM-^Ra ^[[22moptions described later) and the user is using an authentiM-bM-^@M-^P
+ cation agent, the connection to the agent is automatically forwarded to
+ the remote side.
+
+ Forwarding of arbitrary TCP/IP connections over the secure channel can be
+ specified either on the command line or in a configuration file. One
+ possible application of TCP/IP forwarding is a secure connection to an
+ electronic purse; another is going through firewalls.
+
+ ^[[1mServer authentication^[[0m
+
+ ^[[1mssh ^[[22mautomatically maintains and checks a database containing identificaM-bM-^@M-^P
+ tions for all hosts it has ever been used with. Host keys are stored in
+ ^[[4m$HOME/.ssh/known_hosts^[[24m in the userM-bM-^@M-^Ys home directory. Additionally, the
+ file ^[[4m/etc/ssh/ssh_known_hosts^[[24m is automatically checked for known hosts.
+ Any new hosts are automatically added to the userM-bM-^@M-^Ys file. If a hostM-bM-^@M-^Ys
+ identification ever changes, ^[[1mssh ^[[22mwarns about this and disables password
+ authentication to prevent a trojan horse from getting the userM-bM-^@M-^Ys passM-bM-^@M-^P
+ word. Another purpose of this mechanism is to prevent manM-bM-^@M-^PinM-bM-^@M-^PtheM-bM-^@M-^Pmiddle
+ attacks which could otherwise be used to circumvent the encryption. The
+ ^[[1mStrictHostKeyChecking ^[[22moption can be used to prevent logins to machines
+ whose host key is not known or has changed.
+
+ The options are as follows:
+
+ ^[[1mM-bMM-^Ra ^[[22mDisables forwarding of the authentication agent connection.
+
+ ^[[1mM-bMM-^RA ^[[22mEnables forwarding of the authentication agent connection. This
+ can also be specified on a perM-bM-^@M-^Phost basis in a configuration
+ file.
+
+ Agent forwarding should be enabled with caution. Users with the
+ ability to bypass file permissions on the remote host (for the
+ agentM-bM-^@M-^Ys UnixM-bM-^@M-^Pdomain socket) can access the local agent through
+ the forwarded connection. An attacker cannot obtain key material
+ from the agent, however they can perform operations on the keys
+ that enable them to authenticate using the identities loaded into
+ the agent.
+
+ ^[[1mM-bMM-^Rb ^[[4m^[[22mbind_address^[[0m
+ Specify the interface to transmit from on machines with multiple
+ interfaces or aliased addresses.
+
+ ^[[1mM-bMM-^Rc ^[[4m^[[22mblowfish|3des|des^[[0m
+ Selects the cipher to use for encrypting the session. ^[[4m3des^[[24m is
+ used by default. It is believed to be secure. ^[[4m3des^[[24m (tripleM-bM-^@M-^Pdes)
+ is an encryptM-bM-^@M-^PdecryptM-bM-^@M-^Pencrypt triple with three different keys.
+ ^[[4mblowfish^[[24m is a fast block cipher, it appears very secure and is
+ much faster than ^[[4m3des^[[24m. ^[[4mdes^[[24m is only supported in the ^[[1mssh ^[[22mclient
+ for interoperability with legacy protocol 1 implementations that
+ do not support the ^[[4m3des^[[24m cipher. Its use is strongly discouraged
+ due to cryptographic weaknesses.
+
+ ^[[1mM-bMM-^Rc ^[[4m^[[22mcipher_spec^[[0m
+ Additionally, for protocol version 2 a commaM-bM-^@M-^Pseparated list of
+ ciphers can be specified in order of preference. See ^[[1mCiphers ^[[22mfor
+ more information.
+
+ ^[[1mM-bMM-^Re ^[[4m^[[22mch|^ch|none^[[0m
+ Sets the escape character for sessions with a pty (default: M-bM-^@M-^X~M-bM-^@M-^Y).
+ The escape character is only recognized at the beginning of a
+ line. The escape character followed by a dot (M-bM-^@M-^X.M-bM-^@M-^Y) closes the
+ connection, followed by controlM-bM-^@M-^PZ suspends the connection, and
+ followed by itself sends the escape character once. Setting the
+ character to M-bM-^@M-^\noneM-bM-^@M-^] disables any escapes and makes the session
+ fully transparent.
+
+ ^[[1mM-bMM-^Rf ^[[22mRequests ^[[1mssh ^[[22mto go to background just before command execution.
+ This is useful if ^[[1mssh ^[[22mis going to ask for passwords or
+ passphrases, but the user wants it in the background. This
+ implies ^[[1mM-bMM-^Rn^[[22m. The recommended way to start X11 programs at a
+ remote site is with something like ^[[1mssh M-bM-^@M-^Pf host xterm^[[22m.
+
+ ^[[1mM-bMM-^Rg ^[[22mAllows remote hosts to connect to local forwarded ports.
+
+ ^[[1mM-bMM-^Ri ^[[4m^[[22midentity_file^[[0m
+ Selects a file from which the identity (private key) for RSA or
+ DSA authentication is read. The default is ^[[4m$HOME/.ssh/identity^[[0m
+ for protocol version 1, and ^[[4m$HOME/.ssh/id_rsa^[[24m and
+ ^[[4m$HOME/.ssh/id_dsa^[[24m for protocol version 2. Identity files may
+ also be specified on a perM-bM-^@M-^Phost basis in the configuration file.
+ It is possible to have multiple ^[[1mM-bMM-^Ri ^[[22moptions (and multiple identiM-bM-^@M-^P
+ ties specified in configuration files).
+
+ ^[[1mM-bMM-^RI ^[[4m^[[22msmartcard_device^[[0m
+ Specifies which smartcard device to use. The argument is the
+ device ^[[1mssh ^[[22mshould use to communicate with a smartcard used for
+ storing the userM-bM-^@M-^Ys private RSA key.
+
+ ^[[1mM-bMM-^Rk ^[[22mDisables forwarding of Kerberos tickets and AFS tokens. This may
+ also be specified on a perM-bM-^@M-^Phost basis in the configuration file.
+
+ ^[[1mM-bMM-^Rl ^[[4m^[[22mlogin_name^[[0m
+ Specifies the user to log in as on the remote machine. This also
+ may be specified on a perM-bM-^@M-^Phost basis in the configuration file.
+
+ ^[[1mM-bMM-^Rm ^[[4m^[[22mmac_spec^[[0m
+ Additionally, for protocol version 2 a commaM-bM-^@M-^Pseparated list of
+ MAC (message authentication code) algorithms can be specified in
+ order of preference. See the ^[[1mMACs ^[[22mkeyword for more information.
+
+ ^[[1mM-bMM-^Rn ^[[22mRedirects stdin from ^[[4m/dev/null^[[24m (actually, prevents reading from
+ stdin). This must be used when ^[[1mssh ^[[22mis run in the background. A
+ common trick is to use this to run X11 programs on a remote
+ machine. For example, ^[[1mssh M-bM-^@M-^Pn shadows.cs.hut.fi emacs & ^[[22mwill
+ start an emacs on shadows.cs.hut.fi, and the X11 connection will
+ be automatically forwarded over an encrypted channel. The ^[[1mssh^[[0m
+ program will be put in the background. (This does not work if
+ ^[[1mssh ^[[22mneeds to ask for a password or passphrase; see also the ^[[1mM-bMM-^Rf^[[0m
+ option.)
+
+ ^[[1mM-bMM-^RN ^[[22mDo not execute a remote command. This is useful for just forM-bM-^@M-^P
+ warding ports (protocol version 2 only).
+
+ ^[[1mM-bMM-^Ro ^[[4m^[[22moption^[[0m
+ Can be used to give options in the format used in the configuraM-bM-^@M-^P
+ tion file. This is useful for specifying options for which there
+ is no separate commandM-bM-^@M-^Pline flag.
+
+ ^[[1mM-bMM-^Rp ^[[4m^[[22mport^[[0m
+ Port to connect to on the remote host. This can be specified on
+ a perM-bM-^@M-^Phost basis in the configuration file.
+
+ ^[[1mM-bMM-^Rq ^[[22mQuiet mode. Causes all warning and diagnostic messages to be
+ suppressed.
+
+ ^[[1mM-bMM-^Rs ^[[22mMay be used to request invocation of a subsystem on the remote
+ system. Subsystems are a feature of the SSH2 protocol which
+ facilitate the use of SSH as a secure transport for other appliM-bM-^@M-^P
+ cations (eg. sftp). The subsystem is specified as the remote comM-bM-^@M-^P
+ mand.
+
+ ^[[1mM-bMM-^Rt ^[[22mForce pseudoM-bM-^@M-^Ptty allocation. This can be used to execute arbiM-bM-^@M-^P
+ trary screenM-bM-^@M-^Pbased programs on a remote machine, which can be
+ very useful, e.g., when implementing menu services. Multiple ^[[1mM-bMM-^Rt^[[0m
+ options force tty allocation, even if ^[[1mssh ^[[22mhas no local tty.
+
+ ^[[1mM-bMM-^RT ^[[22mDisable pseudoM-bM-^@M-^Ptty allocation.
+
+ ^[[1mM-bMM-^Rv ^[[22mVerbose mode. Causes ^[[1mssh ^[[22mto print debugging messages about its
+ progress. This is helpful in debugging connection, authenticaM-bM-^@M-^P
+ tion, and configuration problems. Multiple ^[[1mM-bMM-^Rv ^[[22moptions increases
+ the verbosity. Maximum is 3.
+
+ ^[[1mM-bMM-^Rx ^[[22mDisables X11 forwarding.
+
+ ^[[1mM-bMM-^RX ^[[22mEnables X11 forwarding. This can also be specified on a perM-bM-^@M-^Phost
+ basis in a configuration file.
+
+ X11 forwarding should be enabled with caution. Users with the
+ ability to bypass file permissions on the remote host (for the
+ userM-bM-^@M-^Ys X authorization database) can access the local X11 display
+ through the forwarded connection. An attacker may then be able
+ to perform activities such as keystroke monitoring.
+
+ ^[[1mM-bMM-^RC ^[[22mRequests compression of all data (including stdin, stdout,
+ stderr, and data for forwarded X11 and TCP/IP connections). The
+ compression algorithm is the same used by gzip(1), and the
+ M-bM-^@M-^\levelM-bM-^@M-^] can be controlled by the ^[[1mCompressionLevel ^[[22moption for proM-bM-^@M-^P
+ tocol version 1. Compression is desirable on modem lines and
+ other slow connections, but will only slow down things on fast
+ networks. The default value can be set on a hostM-bM-^@M-^PbyM-bM-^@M-^Phost basis
+ in the configuration files; see the ^[[1mCompression ^[[22moption.
+
+ ^[[1mM-bMM-^RF ^[[4m^[[22mconfigfile^[[0m
+ Specifies an alternative perM-bM-^@M-^Puser configuration file. If a conM-bM-^@M-^P
+ figuration file is given on the command line, the systemM-bM-^@M-^Pwide
+ configuration file (^[[4m/etc/ssh/ssh_config^[[24m) will be ignored. The
+ default for the perM-bM-^@M-^Puser configuration file is ^[[4m$HOME/.ssh/config^[[24m.
+
+ ^[[1mM-bMM-^RL ^[[4m^[[22mport:host:hostport^[[0m
+ Specifies that the given port on the local (client) host is to be
+ forwarded to the given host and port on the remote side. This
+ works by allocating a socket to listen to ^[[4mport^[[24m on the local side,
+ and whenever a connection is made to this port, the connection is
+ forwarded over the secure channel, and a connection is made to
+ ^[[4mhost^[[24m port ^[[4mhostport^[[24m from the remote machine. Port forwardings can
+ also be specified in the configuration file. Only root can forM-bM-^@M-^P
+ ward privileged ports. IPv6 addresses can be specified with an
+ alternative syntax: ^[[4mport/host/hostport^[[0m
+
+ ^[[1mM-bMM-^RR ^[[4m^[[22mport:host:hostport^[[0m
+ Specifies that the given port on the remote (server) host is to
+ be forwarded to the given host and port on the local side. This
+ works by allocating a socket to listen to ^[[4mport^[[24m on the remote
+ side, and whenever a connection is made to this port, the connecM-bM-^@M-^P
+ tion is forwarded over the secure channel, and a connection is
+ made to ^[[4mhost^[[24m port ^[[4mhostport^[[24m from the local machine. Port forwardM-bM-^@M-^P
+ ings can also be specified in the configuration file. Privileged
+ ports can be forwarded only when logging in as root on the remote
+ machine. IPv6 addresses can be specified with an alternative
+ syntax: ^[[4mport/host/hostport^[[0m
+
+ ^[[1mM-bMM-^RD ^[[4m^[[22mport^[[0m
+ Specifies a local M-bM-^@M-^\dynamicM-bM-^@M-^] applicationM-bM-^@M-^Plevel port forwarding.
+ This works by allocating a socket to listen to ^[[4mport^[[24m on the local
+ side, and whenever a connection is made to this port, the connecM-bM-^@M-^P
+ tion is forwarded over the secure channel, and the application
+ protocol is then used to determine where to connect to from the
+ remote machine. Currently the SOCKS4 protocol is supported, and
+ ^[[1mssh ^[[22mwill act as a SOCKS4 server. Only root can forward priviM-bM-^@M-^P
+ leged ports. Dynamic port forwardings can also be specified in
+ the configuration file.
+
+ ^[[1mM-bMM-^R1 ^[[22mForces ^[[1mssh ^[[22mto try protocol version 1 only.
+
+ ^[[1mM-bMM-^R2 ^[[22mForces ^[[1mssh ^[[22mto try protocol version 2 only.
+
+ ^[[1mM-bMM-^R4 ^[[22mForces ^[[1mssh ^[[22mto use IPv4 addresses only.
+
+ ^[[1mM-bMM-^R6 ^[[22mForces ^[[1mssh ^[[22mto use IPv6 addresses only.
+
+^[[1mCONFIGURATION FILES^[[0m
+ ^[[1mssh ^[[22mmay additionally obtain configuration data from a perM-bM-^@M-^Puser configuraM-bM-^@M-^P
+ tion file and a systemM-bM-^@M-^Pwide configuration file. The file format and conM-bM-^@M-^P
+ figuration options are described in ssh_config(5).
+
+^[[1mENVIRONMENT^[[0m
+ ^[[1mssh ^[[22mwill normally set the following environment variables:
+
+ DISPLAY
+ The DISPLAY variable indicates the location of the X11 server.
+ It is automatically set by ^[[1mssh ^[[22mto point to a value of the form
+ M-bM-^@M-^\hostname:nM-bM-^@M-^] where hostname indicates the host where the shell
+ runs, and n is an integer >= 1. ^[[1mssh ^[[22muses this special value to
+ forward X11 connections over the secure channel. The user should
+ normally not set DISPLAY explicitly, as that will render the X11
+ connection insecure (and will require the user to manually copy
+ any required authorization cookies).
+
+ HOME Set to the path of the userM-bM-^@M-^Ys home directory.
+
+ LOGNAME
+ Synonym for USER; set for compatibility with systems that use
+ this variable.
+
+ MAIL Set to the path of the userM-bM-^@M-^Ys mailbox.
+
+ PATH Set to the default PATH, as specified when compiling ^[[1mssh^[[22m.
+
+ SSH_ASKPASS
+ If ^[[1mssh ^[[22mneeds a passphrase, it will read the passphrase from the
+ current terminal if it was run from a terminal. If ^[[1mssh ^[[22mdoes not
+ have a terminal associated with it but DISPLAY and SSH_ASKPASS
+ are set, it will execute the program specified by SSH_ASKPASS and
+ open an X11 window to read the passphrase. This is particularly
+ useful when calling ^[[1mssh ^[[22mfrom a ^[[4m.Xsession^[[24m or related script.
+ (Note that on some machines it may be necessary to redirect the
+ input from ^[[4m/dev/null^[[24m to make this work.)
+
+ SSH_AUTH_SOCK
+ Identifies the path of a unixM-bM-^@M-^Pdomain socket used to communicate
+ with the agent.
+
+ SSH_CONNECTION
+ Identifies the client and server ends of the connection. The
+ variable contains four spaceM-bM-^@M-^Pseparated values: client ipM-bM-^@M-^Paddress,
+ client port number, server ipM-bM-^@M-^Paddress and server port number.
+
+ SSH_ORIGINAL_COMMAND
+ The variable contains the original command line if a forced comM-bM-^@M-^P
+ mand is executed. It can be used to extract the original arguM-bM-^@M-^P
+ ments.
+
+ SSH_TTY
+ This is set to the name of the tty (path to the device) associM-bM-^@M-^P
+ ated with the current shell or command. If the current session
+ has no tty, this variable is not set.
+
+ TZ The timezone variable is set to indicate the present timezone if
+ it was set when the daemon was started (i.e., the daemon passes
+ the value on to new connections).
+
+ USER Set to the name of the user logging in.
+
+ Additionally, ^[[1mssh ^[[22mreads ^[[4m$HOME/.ssh/environment^[[24m, and adds lines of the
+ format M-bM-^@M-^\VARNAME=valueM-bM-^@M-^] to the environment if the file exists and if users
+ are allowed to change their environment. See the ^[[1mPermitUserEnvironment^[[0m
+ option in sshd_config(5).
+
+^[[1mFILES^[[0m
+ $HOME/.ssh/known_hosts
+ Records host keys for all hosts the user has logged into that are
+ not in ^[[4m/etc/ssh/ssh_known_hosts^[[24m. See sshd(8).
+
+ $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
+ Contains the authentication identity of the user. They are for
+ protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
+ These files contain sensitive data and should be readable by the
+ user but not accessible by others (read/write/execute). Note
+ that ^[[1mssh ^[[22mignores a private key file if it is accessible by othM-bM-^@M-^P
+ ers. It is possible to specify a passphrase when generating the
+ key; the passphrase will be used to encrypt the sensitive part of
+ this file using 3DES.
+
+ $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
+ Contains the public key for authentication (public part of the
+ identity file in humanM-bM-^@M-^Preadable form). The contents of the
+ ^[[4m$HOME/.ssh/identity.pub^[[24m file should be added to
+ ^[[4m$HOME/.ssh/authorized_keys^[[24m on all machines where the user wishes
+ to log in using protocol version 1 RSA authentication. The conM-bM-^@M-^P
+ tents of the ^[[4m$HOME/.ssh/id_dsa.pub^[[24m and ^[[4m$HOME/.ssh/id_rsa.pub^[[24m file
+ should be added to ^[[4m$HOME/.ssh/authorized_keys^[[24m on all machines
+ where the user wishes to log in using protocol version 2 DSA/RSA
+ authentication. These files are not sensitive and can (but need
+ not) be readable by anyone. These files are never used automatiM-bM-^@M-^P
+ cally and are not necessary; they are only provided for the conM-bM-^@M-^P
+ venience of the user.
+
+ $HOME/.ssh/config
+ This is the perM-bM-^@M-^Puser configuration file. The file format and
+ configuration options are described in ssh_config(5).
+
+ $HOME/.ssh/authorized_keys
+ Lists the public keys (RSA/DSA) that can be used for logging in
+ as this user. The format of this file is described in the
+ sshd(8) manual page. In the simplest form the format is the same
+ as the .pub identity files. This file is not highly sensitive,
+ but the recommended permissions are read/write for the user, and
+ not accessible by others.
+
+ /etc/ssh/ssh_known_hosts
+ Systemwide list of known host keys. This file should be prepared
+ by the system administrator to contain the public host keys of
+ all machines in the organization. This file should be worldM-bM-^@M-^P
+ readable. This file contains public keys, one per line, in the
+ following format (fields separated by spaces): system name, pubM-bM-^@M-^P
+ lic key and optional comment field. When different names are
+ used for the same machine, all such names should be listed, sepaM-bM-^@M-^P
+ rated by commas. The format is described on the sshd(8) manual
+ page.
+
+ The canonical system name (as returned by name servers) is used
+ by sshd(8) to verify the client host when logging in; other names
+ are needed because ^[[1mssh ^[[22mdoes not convert the userM-bM-^@M-^Psupplied name to
+ a canonical name before checking the key, because someone with
+ access to the name servers would then be able to fool host
+ authentication.
+
+ /etc/ssh/ssh_config
+ Systemwide configuration file. The file format and configuration
+ options are described in ssh_config(5).
+
+ /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key,
+ /etc/ssh/ssh_host_rsa_key
+ These three files contain the private parts of the host keys and
+ are used for ^[[1mRhostsRSAAuthentication ^[[22mand ^[[1mHostbasedAuthentication^[[22m.
+ If the protocol version 1 ^[[1mRhostsRSAAuthentication ^[[22mmethod is used,
+ ^[[1mssh ^[[22mmust be setuid root, since the host key is readable only by
+ root. For protocol version 2, ^[[1mssh ^[[22muses sshM-bM-^@M-^Pkeysign(8) to access
+ the host keys for ^[[1mHostbasedAuthentication^[[22m. This eliminates the
+ requirement that ^[[1mssh ^[[22mbe setuid root when that authentication
+ method is used. By default ^[[1mssh ^[[22mis not setuid root.
+
+ $HOME/.rhosts
+ This file is used in ^[[4m.rhosts^[[24m authentication to list the host/user
+ pairs that are permitted to log in. (Note that this file is also
+ used by rlogin and rsh, which makes using this file insecure.)
+ Each line of the file contains a host name (in the canonical form
+ returned by name servers), and then a user name on that host,
+ separated by a space. On some machines this file may need to be
+ worldM-bM-^@M-^Preadable if the userM-bM-^@M-^Ys home directory is on a NFS partiM-bM-^@M-^P
+ tion, because sshd(8) reads it as root. Additionally, this file
+ must be owned by the user, and must not have write permissions
+ for anyone else. The recommended permission for most machines is
+ read/write for the user, and not accessible by others.
+
+ Note that by default sshd(8) will be installed so that it
+ requires successful RSA host authentication before permitting
+ .rhosts authentication. If the server machine does not have the
+ clientM-bM-^@M-^Ys host key in ^[[4m/etc/ssh/ssh_known_hosts^[[24m, it can be stored
+ in ^[[4m$HOME/.ssh/known_hosts^[[24m. The easiest way to do this is to conM-bM-^@M-^P
+ nect back to the client from the server machine using ssh; this
+ will automatically add the host key to ^[[4m$HOME/.ssh/known_hosts^[[24m.
+
+ $HOME/.shosts
+ This file is used exactly the same way as ^[[4m.rhosts^[[24m. The purpose
+ for having this file is to be able to use rhosts authentication
+ with ^[[1mssh ^[[22mwithout permitting login with ^[[1mrlogin ^[[22mor rsh(1).
+
+ /etc/hosts.equiv
+ This file is used during ^[[4m.rhosts^[[24m ^[[4mauthentication.^[[24m It contains
+ canonical hosts names, one per line (the full format is described
+ on the sshd(8) manual page). If the client host is found in this
+ file, login is automatically permitted provided client and server
+ user names are the same. Additionally, successful RSA host
+ authentication is normally required. This file should only be
+ writable by root.
+
+ /etc/shosts.equiv
+ This file is processed exactly as ^[[4m/etc/hosts.equiv^[[24m. This file
+ may be useful to permit logins using ^[[1mssh ^[[22mbut not using
+ rsh/rlogin.
+
+ /etc/ssh/sshrc
+ Commands in this file are executed by ^[[1mssh ^[[22mwhen the user logs in
+ just before the userM-bM-^@M-^Ys shell (or command) is started. See the
+ sshd(8) manual page for more information.
+
+ $HOME/.ssh/rc
+ Commands in this file are executed by ^[[1mssh ^[[22mwhen the user logs in
+ just before the userM-bM-^@M-^Ys shell (or command) is started. See the
+ sshd(8) manual page for more information.
+
+ $HOME/.ssh/environment
+ Contains additional definitions for environment variables, see
+ section ^[[4mENVIRONMENT^[[24m above.
+
+^[[1mDIAGNOSTICS^[[0m
+ ^[[1mssh ^[[22mexits with the exit status of the remote command or with 255 if an
+ error occurred.
+
+^[[1mAUTHORS^[[0m
+ OpenSSH is a derivative of the original and free ssh 1.2.12 release by
+ Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
+ de Raadt and Dug Song removed many bugs, reM-bM-^@M-^Padded newer features and creM-bM-^@M-^P
+ ated OpenSSH. Markus Friedl contributed the support for SSH protocol
+ versions 1.5 and 2.0.
+
+^[[1mSEE ALSO^[[0m
+ rsh(1), scp(1), sftp(1), sshM-bM-^@M-^Padd(1), sshM-bM-^@M-^Pagent(1), sshM-bM-^@M-^Pkeygen(1),
+ telnet(1), ssh_config(5), sshM-bM-^@M-^Pkeysign(8), sshd(8)
+
+ T. Ylonen, T. Kivinen, M. Saarinen, T. Rinne, and S. Lehtinen, ^[[4mSSH^[[0m
+ ^[[4mProtocol^[[24m ^[[4mArchitecture^[[24m, draftM-bM-^@M-^PietfM-bM-^@M-^PsecshM-bM-^@M-^ParchitectureM-bM-^@M-^P12.txt, January
+ 2002, work in progress material.
+
+BSD September 25, 1999 BSD