3 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 .\" All rights reserved
7 .\" As far as I am concerned, the code I have written for this software
8 .\" can be used freely for any purpose. Any derived versions of this
9 .\" software must be clearly marked as such, and if the derived work is
10 .\" incompatible with the protocol description in the RFC file, it must be
11 .\" called by a name other than "ssh" or "Secure Shell".
13 .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
14 .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
15 .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
17 .\" Redistribution and use in source and binary forms, with or without
18 .\" modification, are permitted provided that the following conditions
20 .\" 1. Redistributions of source code must retain the above copyright
21 .\" notice, this list of conditions and the following disclaimer.
22 .\" 2. Redistributions in binary form must reproduce the above copyright
23 .\" notice, this list of conditions and the following disclaimer in the
24 .\" documentation and/or other materials provided with the distribution.
26 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 .\" $OpenBSD: ssh.1,v 1.168 2003/03/28 10:11:43 jmc Exp $
38 .Dd September 25, 1999
43 .Nd OpenSSH SSH client (remote login program)
46 .Op Fl l Ar login_name
47 .Ar hostname | user@hostname
52 .Op Fl afgknqstvxACNTX1246
53 .Op Fl b Ar bind_address
54 .Op Fl c Ar cipher_spec
55 .Op Fl e Ar escape_char
56 .Op Fl i Ar identity_file
57 .Op Fl l Ar login_name
61 .Op Fl F Ar configfile
81 .Ar hostname | user@hostname
86 (SSH client) is a program for logging into a remote machine and for
87 executing commands on a remote machine.
88 It is intended to replace
89 rlogin and rsh, and provide secure encrypted communications between
90 two untrusted hosts over an insecure network.
92 arbitrary TCP/IP ports can also be forwarded over the secure channel.
95 connects and logs into the specified
98 his/her identity to the remote machine using one of several methods
99 depending on the protocol version used:
101 .Ss SSH protocol version 1
103 First, if the machine the user logs in from is listed in
106 .Pa /etc/shosts.equiv
107 on the remote machine, and the user names are
108 the same on both sides, the user is immediately permitted to log in.
113 exists in the user's home directory on the
114 remote machine and contains a line containing the name of the client
115 machine and the name of the user on that machine, the user is
117 This form of authentication alone is normally not
118 allowed by the server because it is not secure.
120 The second authentication method is the
124 method combined with RSA-based host authentication.
125 It means that if the login would be permitted by
128 .Pa /etc/hosts.equiv ,
130 .Pa /etc/shosts.equiv ,
131 and if additionally the server can verify the client's
133 .Pa /etc/ssh/ssh_known_hosts
135 .Pa $HOME/.ssh/known_hosts
138 section), only then login is permitted.
139 This authentication method closes security holes due to IP
140 spoofing, DNS spoofing and routing spoofing.
141 [Note to the administrator:
142 .Pa /etc/hosts.equiv ,
144 and the rlogin/rsh protocol in general, are inherently insecure and should be
145 disabled if security is desired.]
147 As a third authentication method,
149 supports RSA based authentication.
150 The scheme is based on public-key cryptography: there are cryptosystems
151 where encryption and decryption are done using separate keys, and it
152 is not possible to derive the decryption key from the encryption key.
153 RSA is one such system.
154 The idea is that each user creates a public/private
155 key pair for authentication purposes.
156 The server knows the public key, and only the user knows the private key.
158 .Pa $HOME/.ssh/authorized_keys
159 lists the public keys that are permitted for logging
161 When the user logs in, the
163 program tells the server which key pair it would like to use for
165 The server checks if this key is permitted, and if
166 so, sends the user (actually the
168 program running on behalf of the user) a challenge, a random number,
169 encrypted by the user's public key.
170 The challenge can only be
171 decrypted using the proper private key.
172 The user's client then decrypts the
173 challenge using the private key, proving that he/she knows the private
174 key but without disclosing it to the server.
177 implements the RSA authentication protocol automatically.
178 The user creates his/her RSA key pair by running
180 This stores the private key in
181 .Pa $HOME/.ssh/identity
182 and the public key in
183 .Pa $HOME/.ssh/identity.pub
184 in the user's home directory.
185 The user should then copy the
188 .Pa $HOME/.ssh/authorized_keys
189 in his/her home directory on the remote machine (the
191 file corresponds to the conventional
193 file, and has one key
194 per line, though the lines can be very long).
195 After this, the user can log in without giving the password.
196 RSA authentication is much
197 more secure than rhosts authentication.
199 The most convenient way to use RSA authentication may be with an
200 authentication agent.
203 for more information.
205 If other authentication methods fail,
207 prompts the user for a password.
208 The password is sent to the remote
209 host for checking; however, since all communications are encrypted,
210 the password cannot be seen by someone listening on the network.
212 .Ss SSH protocol version 2
214 When a user connects using protocol version 2
215 similar authentication methods are available.
216 Using the default values for
217 .Cm PreferredAuthentications ,
218 the client will try to authenticate first using the hostbased method;
219 if this method fails public key authentication is attempted,
220 and finally if this method fails keyboard-interactive and
221 password authentication are tried.
223 The public key method is similar to RSA authentication described
224 in the previous section and allows the RSA or DSA algorithm to be used:
225 The client uses his private key,
226 .Pa $HOME/.ssh/id_dsa
228 .Pa $HOME/.ssh/id_rsa ,
229 to sign the session identifier and sends the result to the server.
230 The server checks whether the matching public key is listed in
231 .Pa $HOME/.ssh/authorized_keys
232 and grants access if both the key is found and the signature is correct.
233 The session identifier is derived from a shared Diffie-Hellman value
234 and is only known to the client and the server.
236 If public key authentication fails or is not available a password
237 can be sent encrypted to the remote host for proving the user's identity.
241 supports hostbased or challenge response authentication.
243 Protocol 2 provides additional mechanisms for confidentiality
244 (the traffic is encrypted using 3DES, Blowfish, CAST128 or Arcfour)
245 and integrity (hmac-md5, hmac-sha1).
246 Note that protocol 1 lacks a strong mechanism for ensuring the
247 integrity of the connection.
249 .Ss Login session and remote execution
251 When the user's identity has been accepted by the server, the server
252 either executes the given command, or logs into the machine and gives
253 the user a normal shell on the remote machine.
254 All communication with
255 the remote command or shell will be automatically encrypted.
257 If a pseudo-terminal has been allocated (normal login session), the
258 user may use the escape characters noted below.
260 If no pseudo tty has been allocated, the
261 session is transparent and can be used to reliably transfer binary
263 On most systems, setting the escape character to
265 will also make the session transparent even if a tty is used.
267 The session terminates when the command or shell on the remote
268 machine exits and all X11 and TCP/IP connections have been closed.
269 The exit status of the remote program is returned as the exit status
273 .Ss Escape Characters
275 When a pseudo terminal has been requested, ssh supports a number of functions
276 through the use of an escape character.
278 A single tilde character can be sent as
280 or by following the tilde by a character other than those described below.
281 The escape character must always follow a newline to be interpreted as
283 The escape character can be changed in configuration files using the
285 configuration directive or on the command line by the
289 The supported escapes (assuming the default
298 List forwarded connections
300 Background ssh at logout when waiting for forwarded connection / X11 sessions
303 Display a list of escape characters
305 Open command line (only useful for adding port forwardings using the
311 Request rekeying of the connection (only useful for SSH protocol version 2
312 and if the peer supports it)
315 .Ss X11 and TCP forwarding
321 (or, see the description of the
325 options described later)
326 and the user is using X11 (the
328 environment variable is set), the connection to the X11 display is
329 automatically forwarded to the remote side in such a way that any X11
330 programs started from the shell (or command) will go through the
331 encrypted channel, and the connection to the real X server will be made
332 from the local machine.
333 The user should not manually set
335 Forwarding of X11 connections can be
336 configured on the command line or in configuration files.
342 will point to the server machine, but with a display number greater
344 This is normal, and happens because
348 X server on the server machine for forwarding the
349 connections over the encrypted channel.
352 will also automatically set up Xauthority data on the server machine.
353 For this purpose, it will generate a random authorization cookie,
354 store it in Xauthority on the server, and verify that any forwarded
355 connections carry this cookie and replace it by the real cookie when
356 the connection is opened.
357 The real authentication cookie is never
358 sent to the server machine (and no cookies are sent in the plain).
364 (or, see the description of the
368 options described later) and
369 the user is using an authentication agent, the connection to the agent
370 is automatically forwarded to the remote side.
372 Forwarding of arbitrary TCP/IP connections over the secure channel can
373 be specified either on the command line or in a configuration file.
374 One possible application of TCP/IP forwarding is a secure connection to an
375 electronic purse; another is going through firewalls.
377 .Ss Server authentication
380 automatically maintains and checks a database containing
381 identifications for all hosts it has ever been used with.
382 Host keys are stored in
383 .Pa $HOME/.ssh/known_hosts
384 in the user's home directory.
385 Additionally, the file
386 .Pa /etc/ssh/ssh_known_hosts
387 is automatically checked for known hosts.
388 Any new hosts are automatically added to the user's file.
389 If a host's identification
392 warns about this and disables password authentication to prevent a
393 trojan horse from getting the user's password.
395 this mechanism is to prevent man-in-the-middle attacks which could
396 otherwise be used to circumvent the encryption.
398 .Cm StrictHostKeyChecking
399 option can be used to prevent logins to machines whose
400 host key is not known or has changed.
402 The options are as follows:
405 Disables forwarding of the authentication agent connection.
407 Enables forwarding of the authentication agent connection.
408 This can also be specified on a per-host basis in a configuration file.
410 Agent forwarding should be enabled with caution.
411 Users with the ability to bypass file permissions on the remote host
412 (for the agent's Unix-domain socket)
413 can access the local agent through the forwarded connection.
414 An attacker cannot obtain key material from the agent,
415 however they can perform operations on the keys that enable them to
416 authenticate using the identities loaded into the agent.
417 .It Fl b Ar bind_address
418 Specify the interface to transmit from on machines with multiple
419 interfaces or aliased addresses.
420 .It Fl c Ar blowfish|3des|des
421 Selects the cipher to use for encrypting the session.
424 It is believed to be secure.
426 (triple-des) is an encrypt-decrypt-encrypt triple with three different keys.
428 is a fast block cipher, it appears very secure and is much faster than
431 is only supported in the
433 client for interoperability with legacy protocol 1 implementations
434 that do not support the
437 Its use is strongly discouraged due to cryptographic weaknesses.
438 .It Fl c Ar cipher_spec
439 Additionally, for protocol version 2 a comma-separated list of ciphers can
440 be specified in order of preference.
443 for more information.
444 .It Fl e Ar ch|^ch|none
445 Sets the escape character for sessions with a pty (default:
447 The escape character is only recognized at the beginning of a line.
448 The escape character followed by a dot
450 closes the connection, followed
451 by control-Z suspends the connection, and followed by itself sends the
452 escape character once.
453 Setting the character to
455 disables any escapes and makes the session fully transparent.
459 to go to background just before command execution.
462 is going to ask for passwords or passphrases, but the user
463 wants it in the background.
466 The recommended way to start X11 programs at a remote site is with
468 .Ic ssh -f host xterm .
470 Allows remote hosts to connect to local forwarded ports.
471 .It Fl i Ar identity_file
472 Selects a file from which the identity (private key) for
473 RSA or DSA authentication is read.
475 .Pa $HOME/.ssh/identity
476 for protocol version 1, and
477 .Pa $HOME/.ssh/id_rsa
479 .Pa $HOME/.ssh/id_dsa
480 for protocol version 2.
481 Identity files may also be specified on
482 a per-host basis in the configuration file.
483 It is possible to have multiple
485 options (and multiple identities specified in
486 configuration files).
487 .It Fl I Ar smartcard_device
488 Specifies which smartcard device to use. The argument is
491 should use to communicate with a smartcard used for storing the user's
494 Disables forwarding of Kerberos tickets and AFS tokens.
495 This may also be specified on a per-host basis in the configuration file.
496 .It Fl l Ar login_name
497 Specifies the user to log in as on the remote machine.
498 This also may be specified on a per-host basis in the configuration file.
500 Additionally, for protocol version 2 a comma-separated list of MAC
501 (message authentication code) algorithms can
502 be specified in order of preference.
505 keyword for more information.
509 (actually, prevents reading from stdin).
510 This must be used when
512 is run in the background.
513 A common trick is to use this to run X11 programs on a remote machine.
515 .Ic ssh -n shadows.cs.hut.fi emacs &
516 will start an emacs on shadows.cs.hut.fi, and the X11
517 connection will be automatically forwarded over an encrypted channel.
520 program will be put in the background.
521 (This does not work if
523 needs to ask for a password or passphrase; see also the
527 Do not execute a remote command.
528 This is useful for just forwarding ports
529 (protocol version 2 only).
531 Can be used to give options in the format used in the configuration file.
532 This is useful for specifying options for which there is no separate
535 Port to connect to on the remote host.
536 This can be specified on a
537 per-host basis in the configuration file.
540 Causes all warning and diagnostic messages to be suppressed.
542 May be used to request invocation of a subsystem on the remote system. Subsystems are a feature of the SSH2 protocol which facilitate the use
543 of SSH as a secure transport for other applications (eg. sftp). The
544 subsystem is specified as the remote command.
546 Force pseudo-tty allocation.
547 This can be used to execute arbitrary
548 screen-based programs on a remote machine, which can be very useful,
549 e.g., when implementing menu services.
552 options force tty allocation, even if
556 Disable pseudo-tty allocation.
561 to print debugging messages about its progress.
563 debugging connection, authentication, and configuration problems.
566 options increases the verbosity.
569 Disables X11 forwarding.
571 Enables X11 forwarding.
572 This can also be specified on a per-host basis in a configuration file.
574 X11 forwarding should be enabled with caution.
575 Users with the ability to bypass file permissions on the remote host
576 (for the user's X authorization database)
577 can access the local X11 display through the forwarded connection.
578 An attacker may then be able to perform activities such as keystroke monitoring.
580 Requests compression of all data (including stdin, stdout, stderr, and
581 data for forwarded X11 and TCP/IP connections).
582 The compression algorithm is the same used by
586 can be controlled by the
588 option for protocol version 1.
589 Compression is desirable on modem lines and other
590 slow connections, but will only slow down things on fast networks.
591 The default value can be set on a host-by-host basis in the
592 configuration files; see the
595 .It Fl F Ar configfile
596 Specifies an alternative per-user configuration file.
597 If a configuration file is given on the command line,
598 the system-wide configuration file
599 .Pq Pa /etc/ssh/ssh_config
601 The default for the per-user configuration file is
602 .Pa $HOME/.ssh/config .
603 .It Fl L Ar port:host:hostport
604 Specifies that the given port on the local (client) host is to be
605 forwarded to the given host and port on the remote side.
606 This works by allocating a socket to listen to
608 on the local side, and whenever a connection is made to this port, the
609 connection is forwarded over the secure channel, and a connection is
614 from the remote machine.
615 Port forwardings can also be specified in the configuration file.
616 Only root can forward privileged ports.
617 IPv6 addresses can be specified with an alternative syntax:
618 .Ar port/host/hostport
619 .It Fl R Ar port:host:hostport
620 Specifies that the given port on the remote (server) host is to be
621 forwarded to the given host and port on the local side.
622 This works by allocating a socket to listen to
624 on the remote side, and whenever a connection is made to this port, the
625 connection is forwarded over the secure channel, and a connection is
630 from the local machine.
631 Port forwardings can also be specified in the configuration file.
632 Privileged ports can be forwarded only when
633 logging in as root on the remote machine.
634 IPv6 addresses can be specified with an alternative syntax:
635 .Ar port/host/hostport
639 application-level port forwarding.
640 This works by allocating a socket to listen to
642 on the local side, and whenever a connection is made to this port, the
643 connection is forwarded over the secure channel, and the application
644 protocol is then used to determine where to connect to from the
646 Currently the SOCKS4 protocol is supported, and
648 will act as a SOCKS4 server.
649 Only root can forward privileged ports.
650 Dynamic port forwardings can also be specified in the configuration file.
654 to try protocol version 1 only.
658 to try protocol version 2 only.
662 to use IPv4 addresses only.
666 to use IPv6 addresses only.
668 .Sh CONFIGURATION FILES
670 may additionally obtain configuration data from
671 a per-user configuration file and a system-wide configuration file.
672 The file format and configuration options are described in
676 will normally set the following environment variables:
681 variable indicates the location of the X11 server.
682 It is automatically set by
684 to point to a value of the form
686 where hostname indicates
687 the host where the shell runs, and n is an integer >= 1.
689 uses this special value to forward X11 connections over the secure
691 The user should normally not set
694 will render the X11 connection insecure (and will require the user to
695 manually copy any required authorization cookies).
697 Set to the path of the user's home directory.
701 set for compatibility with systems that use this variable.
703 Set to the path of the user's mailbox.
707 as specified when compiling
712 needs a passphrase, it will read the passphrase from the current
713 terminal if it was run from a terminal.
716 does not have a terminal associated with it but
720 are set, it will execute the program specified by
722 and open an X11 window to read the passphrase.
723 This is particularly useful when calling
728 (Note that on some machines it
729 may be necessary to redirect the input from
733 Identifies the path of a unix-domain socket used to communicate with the
735 .It Ev SSH_CONNECTION
736 Identifies the client and server ends of the connection.
737 The variable contains
738 four space-separated values: client ip-address, client port number,
739 server ip-address and server port number.
740 .It Ev SSH_ORIGINAL_COMMAND
741 The variable contains the original command line if a forced command
743 It can be used to extract the original arguments.
745 This is set to the name of the tty (path to the device) associated
746 with the current shell or command.
747 If the current session has no tty,
748 this variable is not set.
750 The timezone variable is set to indicate the present timezone if it
751 was set when the daemon was started (i.e., the daemon passes the value
752 on to new connections).
754 Set to the name of the user logging in.
760 .Pa $HOME/.ssh/environment ,
761 and adds lines of the format
763 to the environment if the file exists and if users are allowed to
764 change their environment.
766 .Cm PermitUserEnvironment
771 .It Pa $HOME/.ssh/known_hosts
772 Records host keys for all hosts the user has logged into that are not
774 .Pa /etc/ssh/ssh_known_hosts .
777 .It Pa $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
778 Contains the authentication identity of the user.
779 They are for protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
781 contain sensitive data and should be readable by the user but not
782 accessible by others (read/write/execute).
785 ignores a private key file if it is accessible by others.
786 It is possible to specify a passphrase when
787 generating the key; the passphrase will be used to encrypt the
788 sensitive part of this file using 3DES.
789 .It Pa $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
790 Contains the public key for authentication (public part of the
791 identity file in human-readable form).
793 .Pa $HOME/.ssh/identity.pub
794 file should be added to
795 .Pa $HOME/.ssh/authorized_keys
797 where the user wishes to log in using protocol version 1 RSA authentication.
799 .Pa $HOME/.ssh/id_dsa.pub
801 .Pa $HOME/.ssh/id_rsa.pub
802 file should be added to
803 .Pa $HOME/.ssh/authorized_keys
805 where the user wishes to log in using protocol version 2 DSA/RSA authentication.
807 sensitive and can (but need not) be readable by anyone.
809 never used automatically and are not necessary; they are only provided for
810 the convenience of the user.
811 .It Pa $HOME/.ssh/config
812 This is the per-user configuration file.
813 The file format and configuration options are described in
815 .It Pa $HOME/.ssh/authorized_keys
816 Lists the public keys (RSA/DSA) that can be used for logging in as this user.
817 The format of this file is described in the
820 In the simplest form the format is the same as the .pub
822 This file is not highly sensitive, but the recommended
823 permissions are read/write for the user, and not accessible by others.
824 .It Pa /etc/ssh/ssh_known_hosts
825 Systemwide list of known host keys.
826 This file should be prepared by the
827 system administrator to contain the public host keys of all machines in the
829 This file should be world-readable.
831 public keys, one per line, in the following format (fields separated
832 by spaces): system name, public key and optional comment field.
833 When different names are used
834 for the same machine, all such names should be listed, separated by
836 The format is described on the
840 The canonical system name (as returned by name servers) is used by
842 to verify the client host when logging in; other names are needed because
844 does not convert the user-supplied name to a canonical name before
845 checking the key, because someone with access to the name servers
846 would then be able to fool host authentication.
847 .It Pa /etc/ssh/ssh_config
848 Systemwide configuration file.
849 The file format and configuration options are described in
851 .It Pa /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
852 These three files contain the private parts of the host keys
854 .Cm RhostsRSAAuthentication
856 .Cm HostbasedAuthentication .
857 If the protocol version 1
858 .Cm RhostsRSAAuthentication
861 must be setuid root, since the host key is readable only by root.
862 For protocol version 2,
866 to access the host keys for
867 .Cm HostbasedAuthentication .
868 This eliminates the requirement that
870 be setuid root when that authentication method is used.
877 authentication to list the
878 host/user pairs that are permitted to log in.
879 (Note that this file is
880 also used by rlogin and rsh, which makes using this file insecure.)
881 Each line of the file contains a host name (in the canonical form
882 returned by name servers), and then a user name on that host,
883 separated by a space.
884 On some machines this file may need to be
885 world-readable if the user's home directory is on a NFS partition,
889 Additionally, this file must be owned by the user,
890 and must not have write permissions for anyone else.
892 permission for most machines is read/write for the user, and not
893 accessible by others.
897 will be installed so that it requires successful RSA host
898 authentication before permitting \s+2.\s0rhosts authentication.
899 If the server machine does not have the client's host key in
900 .Pa /etc/ssh/ssh_known_hosts ,
902 .Pa $HOME/.ssh/known_hosts .
903 The easiest way to do this is to
904 connect back to the client from the server machine using ssh; this
905 will automatically add the host key to
906 .Pa $HOME/.ssh/known_hosts .
908 This file is used exactly the same way as
911 having this file is to be able to use rhosts authentication with
913 without permitting login with
917 .It Pa /etc/hosts.equiv
918 This file is used during
919 .Pa \&.rhosts authentication.
921 canonical hosts names, one per line (the full format is described on
925 If the client host is found in this file, login is
926 automatically permitted provided client and server user names are the
928 Additionally, successful RSA host authentication is normally
930 This file should only be writable by root.
931 .It Pa /etc/shosts.equiv
932 This file is processed exactly as
933 .Pa /etc/hosts.equiv .
934 This file may be useful to permit logins using
936 but not using rsh/rlogin.
937 .It Pa /etc/ssh/sshrc
938 Commands in this file are executed by
940 when the user logs in just before the user's shell (or command) is started.
943 manual page for more information.
945 Commands in this file are executed by
947 when the user logs in just before the user's shell (or command) is
951 manual page for more information.
952 .It Pa $HOME/.ssh/environment
953 Contains additional definitions for environment variables, see section
959 exits with the exit status of the remote command or with 255
960 if an error occurred.
962 OpenSSH is a derivative of the original and free
963 ssh 1.2.12 release by Tatu Ylonen.
964 Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
965 Theo de Raadt and Dug Song
966 removed many bugs, re-added newer features and
968 Markus Friedl contributed the support for SSH
969 protocol versions 1.5 and 2.0.
987 .%T "SSH Protocol Architecture"
988 .%N draft-ietf-secsh-architecture-12.txt
990 .%O work in progress material
andersk / gssapi-openssh.git / blob