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_config.5,v 1.122 2009/10/28 16:38:18 reyk Exp $
43 .Nd OpenSSH SSH client configuration files
46 .Nm /etc/ssh/ssh_config
49 obtains configuration data from the following sources in
52 .Bl -enum -offset indent -compact
56 user's configuration file
59 system-wide configuration file
60 .Pq Pa /etc/ssh/ssh_config
63 For each parameter, the first obtained value
65 The configuration files contain sections separated by
67 specifications, and that section is only applied for hosts that
68 match one of the patterns given in the specification.
69 The matched host name is the one given on the command line.
71 Since the first obtained value for each parameter is used, more
72 host-specific declarations should be given near the beginning of the
73 file, and general defaults at the end.
75 The configuration file has the following format:
77 Empty lines and lines starting with
80 Otherwise a line is of the format
81 .Dq keyword arguments .
82 Configuration options may be separated by whitespace or
83 optional whitespace and exactly one
85 the latter format is useful to avoid the need to quote whitespace
86 when specifying configuration options using the
93 Arguments may optionally be enclosed in double quotes
95 in order to represent arguments containing spaces.
98 keywords and their meanings are as follows (note that
99 keywords are case-insensitive and arguments are case-sensitive):
102 Restricts the following declarations (up to the next
104 keyword) to be only for those hosts that match one of the patterns
105 given after the keyword.
106 If more than one pattern is provided, they should be separated by whitespace.
109 as a pattern can be used to provide global
110 defaults for all hosts.
113 argument given on the command line (i.e. the name is not converted to
114 a canonicalized host name before matching).
118 for more information on patterns.
120 Specifies which address family to use when connecting.
130 passphrase/password querying will be disabled.
131 This option is useful in scripts and other batch jobs where no user
132 is present to supply the password.
140 Use the specified address on the local machine as the source address of
142 Only useful on systems with more than one address.
143 Note that this option does not work if
144 .Cm UsePrivilegedPort
147 .It Cm ChallengeResponseAuthentication
148 Specifies whether to use challenge-response authentication.
149 The argument to this keyword must be
156 If this flag is set to
159 will additionally check the host IP address in the
162 This allows ssh to detect if a host key changed due to DNS spoofing.
163 If the option is set to
165 the check will not be executed.
169 Specifies the cipher to use for encrypting the session
170 in protocol version 1.
178 is only supported in the
180 client for interoperability with legacy protocol 1 implementations
181 that do not support the
184 Its use is strongly discouraged due to cryptographic weaknesses.
188 Specifies the ciphers allowed for protocol version 2
189 in order of preference.
190 Multiple ciphers must be comma-separated.
191 The supported ciphers are
206 .Bd -literal -offset 3n
207 aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
208 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
211 .It Cm ClearAllForwardings
212 Specifies that all local, remote, and dynamic port forwardings
213 specified in the configuration files or on the command line be
215 This option is primarily useful when used from the
217 command line to clear port forwardings set in
218 configuration files, and is automatically set by
229 Specifies whether to use compression.
236 .It Cm CompressionLevel
237 Specifies the compression level to use if compression is enabled.
238 The argument must be an integer from 1 (fast) to 9 (slow, best).
239 The default level is 6, which is good for most applications.
240 The meaning of the values is the same as in
242 Note that this option applies to protocol version 1 only.
243 .It Cm ConnectionAttempts
244 Specifies the number of tries (one per second) to make before exiting.
245 The argument must be an integer.
246 This may be useful in scripts if the connection sometimes fails.
248 .It Cm ConnectTimeout
249 Specifies the timeout (in seconds) used when connecting to the
250 SSH server, instead of using the default system TCP timeout.
251 This value is used only when the target is down or really unreachable,
252 not when it refuses the connection.
254 Enables the sharing of multiple sessions over a single network connection.
258 will listen for connections on a control socket specified using the
261 Additional sessions can connect to this socket using the same
268 These sessions will try to reuse the master instance's network connection
269 rather than initiating new ones, but will fall back to connecting normally
270 if the control socket does not exist, or is not listening.
275 to listen for control connections, but require confirmation using the
277 program before they are accepted (see
283 ssh will continue without connecting to a master instance.
287 forwarding is supported over these multiplexed connections, however the
288 display and agent forwarded will be the one belonging to the master
289 connection i.e. it is not possible to forward multiple displays or agents.
291 Two additional options allow for opportunistic multiplexing: try to use a
292 master connection but fall back to creating a new one if one does not already
298 The latter requires confirmation like the
302 Specify the path to the control socket used for connection sharing as described
305 section above or the string
307 to disable connection sharing.
310 will be substituted by the local host name,
312 will be substituted by the target host name,
316 by the remote login username.
317 It is recommended that any
319 used for opportunistic connection sharing include
320 at least %h, %p, and %r.
321 This ensures that shared connections are uniquely identified.
322 .It Cm DynamicForward
323 Specifies that a TCP port on the local machine be forwarded
324 over the secure channel, and the application
325 protocol is then used to determine where to connect to from the
330 .Oo Ar bind_address : Oc Ar port .
332 IPv6 addresses can be specified by enclosing addresses in square brackets or
333 by using an alternative syntax:
334 .Oo Ar bind_address Ns / Oc Ns Ar port .
335 By default, the local port is bound in accordance with the
340 may be used to bind the connection to a specific address.
345 indicates that the listening port be bound for local use only, while an
348 indicates that the port should be available from all interfaces.
350 Currently the SOCKS4 and SOCKS5 protocols are supported, and
352 will act as a SOCKS server.
353 Multiple forwardings may be specified, and
354 additional forwardings can be given on the command line.
355 Only the superuser can forward privileged ports.
356 .It Cm EnableSSHKeysign
357 Setting this option to
359 in the global client configuration file
360 .Pa /etc/ssh/ssh_config
361 enables the use of the helper program
364 .Cm HostbasedAuthentication .
371 This option should be placed in the non-hostspecific section.
374 for more information.
376 Sets the escape character (default:
378 The escape character can also
379 be set on the command line.
380 The argument should be a single character,
382 followed by a letter, or
384 to disable the escape
385 character entirely (making the connection transparent for binary
387 .It Cm ExitOnForwardFailure
390 should terminate the connection if it cannot set up all requested
391 dynamic, tunnel, local, and remote port forwardings.
399 Specifies whether the connection to the authentication agent (if any)
400 will be forwarded to the remote machine.
408 Agent forwarding should be enabled with caution.
409 Users with the ability to bypass file permissions on the remote host
410 (for the agent's Unix-domain socket)
411 can access the local agent through the forwarded connection.
412 An attacker cannot obtain key material from the agent,
413 however they can perform operations on the keys that enable them to
414 authenticate using the identities loaded into the agent.
416 Specifies whether X11 connections will be automatically redirected
417 over the secure channel and
427 X11 forwarding should be enabled with caution.
428 Users with the ability to bypass file permissions on the remote host
429 (for the user's X11 authorization database)
430 can access the local X11 display through the forwarded connection.
431 An attacker may then be able to perform activities such as keystroke monitoring
433 .Cm ForwardX11Trusted
434 option is also enabled.
435 .It Cm ForwardX11Trusted
436 If this option is set to
438 remote X11 clients will have full access to the original X11 display.
440 If this option is set to
442 remote X11 clients will be considered untrusted and prevented
443 from stealing or tampering with data belonging to trusted X11
447 token used for the session will be set to expire after 20 minutes.
448 Remote clients will be refused access after this time.
453 See the X11 SECURITY extension specification for full details on
454 the restrictions imposed on untrusted clients.
456 Specifies whether remote hosts are allowed to connect to local
460 binds local port forwardings to the loopback address.
461 This prevents other remote hosts from connecting to forwarded ports.
463 can be used to specify that ssh
464 should bind local port forwardings to the wildcard address,
465 thus allowing remote hosts to connect to forwarded ports.
472 .It Cm GlobalKnownHostsFile
473 Specifies a file to use for the global
474 host key database instead of
475 .Pa /etc/ssh/ssh_known_hosts .
476 .It Cm GSSAPIAuthentication
477 Specifies whether user authentication based on GSSAPI is allowed.
480 Note that this option applies to protocol version 2 only.
481 .It Cm GSSAPIDelegateCredentials
482 Forward (delegate) credentials to the server.
485 Note that this option applies to protocol version 2 only.
486 .It Cm HashKnownHosts
489 should hash host names and addresses when they are added to
490 .Pa ~/.ssh/known_hosts .
491 These hashed names may be used normally by
495 but they do not reveal identifying information should the file's contents
499 Note that existing names and addresses in known hosts files
500 will not be converted automatically,
501 but may be manually hashed using
503 .It Cm HostbasedAuthentication
504 Specifies whether to try rhosts based authentication with public key
512 This option applies to protocol version 2 only and
514 .Cm RhostsRSAAuthentication .
515 .It Cm HostKeyAlgorithms
516 Specifies the protocol version 2 host key algorithms
517 that the client wants to use in order of preference.
518 The default for this option is:
519 .Dq ssh-rsa,ssh-dss .
521 Specifies an alias that should be used instead of the
522 real host name when looking up or saving the host key
523 in the host key database files.
524 This option is useful for tunneling SSH connections
525 or for multiple servers running on a single host.
527 Specifies the real host name to log into.
528 This can be used to specify nicknames or abbreviations for hosts.
529 The default is the name given on the command line.
530 Numeric IP addresses are also permitted (both on the command line and in
533 .It Cm IdentitiesOnly
536 should only use the authentication identity files configured in the
541 offers more identities.
542 The argument to this keyword must be
546 This option is intended for situations where ssh-agent
547 offers many different identities.
551 Specifies a file from which the user's RSA or DSA authentication identity
555 for protocol version 1, and
559 for protocol version 2.
560 Additionally, any identities represented by the authentication agent
561 will be used for authentication.
563 The file name may use the tilde
564 syntax to refer to a user's home directory or one of the following
567 (local user's home directory),
573 (remote host name) or
577 It is possible to have
578 multiple identity files specified in configuration files; all these
579 identities will be tried in sequence.
580 .It Cm KbdInteractiveAuthentication
581 Specifies whether to use keyboard-interactive authentication.
582 The argument to this keyword must be
588 .It Cm KbdInteractiveDevices
589 Specifies the list of methods to use in keyboard-interactive authentication.
590 Multiple method names must be comma-separated.
591 The default is to use the server specified list.
592 The methods available vary depending on what the server supports.
593 For an OpenSSH server,
594 it may be zero or more of:
600 Specifies a command to execute on the local machine after successfully
601 connecting to the server.
602 The command string extends to the end of the line, and is executed with
604 The following escape character substitutions will be performed:
606 (local user's home directory),
612 (host name as provided on the command line),
616 (remote user name) or
619 This directive is ignored unless
620 .Cm PermitLocalCommand
623 Specifies that a TCP port on the local machine be forwarded over
624 the secure channel to the specified host and port from the remote machine.
625 The first argument must be
627 .Oo Ar bind_address : Oc Ar port
629 and the second argument must be
630 .Ar host : Ns Ar hostport .
631 IPv6 addresses can be specified by enclosing addresses in square brackets or
632 by using an alternative syntax:
633 .Oo Ar bind_address Ns / Oc Ns Ar port
635 .Ar host Ns / Ns Ar hostport .
636 Multiple forwardings may be specified, and additional forwardings can be
637 given on the command line.
638 Only the superuser can forward privileged ports.
639 By default, the local port is bound in accordance with the
644 may be used to bind the connection to a specific address.
649 indicates that the listening port be bound for local use only, while an
652 indicates that the port should be available from all interfaces.
654 Gives the verbosity level that is used when logging messages from
656 The possible values are:
657 QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.
659 DEBUG and DEBUG1 are equivalent.
660 DEBUG2 and DEBUG3 each specify higher levels of verbose output.
662 Specifies the MAC (message authentication code) algorithms
663 in order of preference.
664 The MAC algorithm is used in protocol version 2
665 for data integrity protection.
666 Multiple algorithms must be comma-separated.
668 .Bd -literal -offset indent
669 hmac-md5,hmac-sha1,umac-64@openssh.com,
670 hmac-ripemd160,hmac-sha1-96,hmac-md5-96
672 .It Cm NoHostAuthenticationForLocalhost
673 This option can be used if the home directory is shared across machines.
674 In this case localhost will refer to a different machine on each of
675 the machines and the user will get many warnings about changed host keys.
676 However, this option disables host authentication for localhost.
677 The argument to this keyword must be
681 The default is to check the host key for localhost.
682 .It Cm NumberOfPasswordPrompts
683 Specifies the number of password prompts before giving up.
684 The argument to this keyword must be an integer.
686 .It Cm PasswordAuthentication
687 Specifies whether to use password authentication.
688 The argument to this keyword must be
694 .It Cm PermitLocalCommand
695 Allow local command execution via the
698 .Ic !\& Ns Ar command
708 Specifies the port number to connect on the remote host.
710 .It Cm PreferredAuthentications
711 Specifies the order in which the client should try protocol 2
712 authentication methods.
713 This allows a client to prefer one method (e.g.\&
714 .Cm keyboard-interactive )
715 over another method (e.g.\&
717 The default for this option is:
718 .Do gssapi-with-mic ,
721 keyboard-interactive,
725 Specifies the protocol versions
727 should support in order of preference.
728 The possible values are
732 Multiple versions must be comma-separated.
733 When this option is set to
736 will try version 2 and fall back to version 1
737 if version 2 is not available.
741 Specifies the command to use to connect to the server.
743 string extends to the end of the line, and is executed with
745 In the command string,
747 will be substituted by the host name to
751 The command can be basically anything,
752 and should read from its standard input and write to its standard output.
753 It should eventually connect an
755 server running on some machine, or execute
758 Host key management will be done using the
759 HostName of the host being connected (defaulting to the name typed by
761 Setting the command to
763 disables this option entirely.
766 is not available for connects with a proxy command.
768 This directive is useful in conjunction with
770 and its proxy support.
771 For example, the following directive would connect via an HTTP proxy at
773 .Bd -literal -offset 3n
774 ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p
776 .It Cm PubkeyAuthentication
777 Specifies whether to try public key authentication.
778 The argument to this keyword must be
784 This option applies to protocol version 2 only.
786 Set the routing domain number.
787 The default routing domain is set by the system.
789 Specifies the maximum amount of data that may be transmitted before the
790 session key is renegotiated.
791 The argument is the number of bytes, with an optional suffix of
796 to indicate Kilobytes, Megabytes, or Gigabytes, respectively.
797 The default is between
801 depending on the cipher.
802 This option applies to protocol version 2 only.
804 Specifies that a TCP port on the remote machine be forwarded over
805 the secure channel to the specified host and port from the local machine.
806 The first argument must be
808 .Oo Ar bind_address : Oc Ar port
810 and the second argument must be
811 .Ar host : Ns Ar hostport .
812 IPv6 addresses can be specified by enclosing addresses in square brackets
813 or by using an alternative syntax:
814 .Oo Ar bind_address Ns / Oc Ns Ar port
816 .Ar host Ns / Ns Ar hostport .
817 Multiple forwardings may be specified, and additional
818 forwardings can be given on the command line.
819 Privileged ports can be forwarded only when
820 logging in as root on the remote machine.
826 the listen port will be dynamically allocated on the server and reported
827 to the client at run time.
831 is not specified, the default is to only bind to loopback addresses.
836 or an empty string, then the forwarding is requested to listen on all
840 will only succeed if the server's
842 option is enabled (see
843 .Xr sshd_config 5 ) .
844 .It Cm RhostsRSAAuthentication
845 Specifies whether to try rhosts based authentication with RSA host
853 This option applies to protocol version 1 only and requires
856 .It Cm RSAAuthentication
857 Specifies whether to try RSA authentication.
858 The argument to this keyword must be
862 RSA authentication will only be
863 attempted if the identity file exists, or an authentication agent is
867 Note that this option applies to protocol version 1 only.
869 Specifies what variables from the local
871 should be sent to the server.
872 Note that environment passing is only supported for protocol 2.
873 The server must also support it, and the server must be configured to
874 accept these environment variables.
879 for how to configure the server.
880 Variables are specified by name, which may contain wildcard characters.
881 Multiple environment variables may be separated by whitespace or spread
885 The default is not to send any environment variables.
889 for more information on patterns.
890 .It Cm ServerAliveCountMax
891 Sets the number of server alive messages (see below) which may be
894 receiving any messages back from the server.
895 If this threshold is reached while server alive messages are being sent,
896 ssh will disconnect from the server, terminating the session.
897 It is important to note that the use of server alive messages is very
901 The server alive messages are sent through the encrypted channel
902 and therefore will not be spoofable.
903 The TCP keepalive option enabled by
906 The server alive mechanism is valuable when the client or
907 server depend on knowing when a connection has become inactive.
909 The default value is 3.
911 .Cm ServerAliveInterval
912 (see below) is set to 15 and
913 .Cm ServerAliveCountMax
914 is left at the default, if the server becomes unresponsive,
915 ssh will disconnect after approximately 45 seconds.
916 This option applies to protocol version 2 only.
917 .It Cm ServerAliveInterval
918 Sets a timeout interval in seconds after which if no data has been received
921 will send a message through the encrypted
922 channel to request a response from the server.
924 is 0, indicating that these messages will not be sent to the server.
925 This option applies to protocol version 2 only.
926 .It Cm SmartcardDevice
927 Specifies which smartcard device to use.
928 The argument to this keyword is the device
930 should use to communicate with a smartcard used for storing the user's
932 By default, no device is specified and smartcard support is not activated.
933 .It Cm StrictHostKeyChecking
934 If this flag is set to
937 will never automatically add host keys to the
938 .Pa ~/.ssh/known_hosts
939 file, and refuses to connect to hosts whose host key has changed.
940 This provides maximum protection against trojan horse attacks,
941 though it can be annoying when the
942 .Pa /etc/ssh/ssh_known_hosts
943 file is poorly maintained or when connections to new hosts are
945 This option forces the user to manually
947 If this flag is set to
949 ssh will automatically add new host keys to the
950 user known hosts files.
951 If this flag is set to
954 will be added to the user known host files only after the user
955 has confirmed that is what they really want to do, and
956 ssh will refuse to connect to hosts whose host key has changed.
958 known hosts will be verified automatically in all cases.
967 Specifies whether the system should send TCP keepalive messages to the
969 If they are sent, death of the connection or crash of one
970 of the machines will be properly noticed.
971 However, this means that
972 connections will die if the route is down temporarily, and some people
977 (to send TCP keepalive messages), and the client will notice
978 if the network goes down or the remote host dies.
979 This is important in scripts, and many users want it too.
981 To disable TCP keepalive messages, the value should be set to
986 device forwarding between the client and the server.
997 requests the default tunnel mode, which is
1004 devices to open on the client
1009 The argument must be
1011 .Ar local_tun Op : Ar remote_tun .
1013 The devices may be specified by numerical ID or the keyword
1015 which uses the next available tunnel device.
1018 is not specified, it defaults to
1022 .It Cm UsePrivilegedPort
1023 Specifies whether to use a privileged port for outgoing connections.
1024 The argument must be
1033 must be setuid root.
1034 Note that this option must be set to
1037 .Cm RhostsRSAAuthentication
1040 Specifies the user to log in as.
1041 This can be useful when a different user name is used on different machines.
1042 This saves the trouble of
1043 having to remember to give the user name on the command line.
1044 .It Cm UserKnownHostsFile
1045 Specifies a file to use for the user
1046 host key database instead of
1047 .Pa ~/.ssh/known_hosts .
1048 .It Cm VerifyHostKeyDNS
1049 Specifies whether to verify the remote key using DNS and SSHFP resource
1051 If this option is set to
1053 the client will implicitly trust keys that match a secure fingerprint
1055 Insecure fingerprints will be handled as if this option was set to
1057 If this option is set to
1059 information on fingerprint match will be displayed, but the user will still
1060 need to confirm new host keys according to the
1061 .Cm StrictHostKeyChecking
1063 The argument must be
1070 Note that this option applies to protocol version 2 only.
1073 .Sx VERIFYING HOST KEYS
1076 .It Cm VisualHostKey
1077 If this flag is set to
1079 an ASCII art representation of the remote host key fingerprint is
1080 printed in addition to the hex fingerprint string at login and
1081 for unknown host keys.
1082 If this flag is set to
1084 no fingerprint strings are printed at login and
1085 only the hex fingerprint string will be printed for unknown host keys.
1088 .It Cm XAuthLocation
1089 Specifies the full pathname of the
1093 .Pa /usr/X11R6/bin/xauth .
1098 consists of zero or more non-whitespace characters,
1100 (a wildcard that matches zero or more characters),
1103 (a wildcard that matches exactly one character).
1104 For example, to specify a set of declarations for any host in the
1107 the following pattern could be used:
1111 The following pattern
1112 would match any host in the 192.168.0.[0-9] network range:
1114 .Dl Host 192.168.0.?
1118 is a comma-separated list of patterns.
1119 Patterns within pattern-lists may be negated
1120 by preceding them with an exclamation mark
1123 to allow a key to be used from anywhere within an organisation
1127 the following entry (in authorized_keys) could be used:
1129 .Dl from=\&"!*.dialup.example.com,*.example.com\&"
1132 .It Pa ~/.ssh/config
1133 This is the per-user configuration file.
1134 The format of this file is described above.
1135 This file is used by the SSH client.
1136 Because of the potential for abuse, this file must have strict permissions:
1137 read/write for the user, and not accessible by others.
1138 .It Pa /etc/ssh/ssh_config
1139 Systemwide configuration file.
1140 This file provides defaults for those
1141 values that are not specified in the user's configuration file, and
1142 for those users who do not have a configuration file.
1143 This file must be world-readable.
1148 OpenSSH is a derivative of the original and free
1149 ssh 1.2.12 release by Tatu Ylonen.
1150 Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1151 Theo de Raadt and Dug Song
1152 removed many bugs, re-added newer features and
1154 Markus Friedl contributed the support for SSH
1155 protocol versions 1.5 and 2.0.
andersk / openssh.git / blob