Annotation of src/usr.bin/ssh/ssh_config.5, Revision 1.168
1.1 stevesk 1: .\"
2: .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
3: .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: .\" All rights reserved
5: .\"
6: .\" As far as I am concerned, the code I have written for this software
7: .\" can be used freely for any purpose. Any derived versions of this
8: .\" software must be clearly marked as such, and if the derived work is
9: .\" incompatible with the protocol description in the RFC file, it must be
10: .\" called by a name other than "ssh" or "Secure Shell".
11: .\"
12: .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
13: .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
14: .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
15: .\"
16: .\" Redistribution and use in source and binary forms, with or without
17: .\" modification, are permitted provided that the following conditions
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19: .\" 1. Redistributions of source code must retain the above copyright
20: .\" notice, this list of conditions and the following disclaimer.
21: .\" 2. Redistributions in binary form must reproduce the above copyright
22: .\" notice, this list of conditions and the following disclaimer in the
23: .\" documentation and/or other materials provided with the distribution.
24: .\"
25: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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1.168 ! jmc 36: .\" $OpenBSD: ssh_config.5,v 1.167 2013/08/20 00:11:38 djm Exp $
! 37: .Dd $Mdocdate: August 20 2013 $
1.1 stevesk 38: .Dt SSH_CONFIG 5
39: .Os
40: .Sh NAME
41: .Nm ssh_config
42: .Nd OpenSSH SSH client configuration files
43: .Sh SYNOPSIS
1.98 jmc 44: .Nm ~/.ssh/config
45: .Nm /etc/ssh/ssh_config
1.1 stevesk 46: .Sh DESCRIPTION
1.84 jmc 47: .Xr ssh 1
1.1 stevesk 48: obtains configuration data from the following sources in
49: the following order:
1.79 jmc 50: .Pp
1.2 stevesk 51: .Bl -enum -offset indent -compact
52: .It
53: command-line options
54: .It
55: user's configuration file
1.50 djm 56: .Pq Pa ~/.ssh/config
1.2 stevesk 57: .It
58: system-wide configuration file
59: .Pq Pa /etc/ssh/ssh_config
60: .El
1.1 stevesk 61: .Pp
62: For each parameter, the first obtained value
63: will be used.
1.41 jmc 64: The configuration files contain sections separated by
1.1 stevesk 65: .Dq Host
66: specifications, and that section is only applied for hosts that
67: match one of the patterns given in the specification.
68: The matched host name is the one given on the command line.
69: .Pp
70: Since the first obtained value for each parameter is used, more
71: host-specific declarations should be given near the beginning of the
72: file, and general defaults at the end.
1.80 jmc 73: .Pp
1.1 stevesk 74: The configuration file has the following format:
75: .Pp
76: Empty lines and lines starting with
77: .Ql #
78: are comments.
79: Otherwise a line is of the format
80: .Dq keyword arguments .
81: Configuration options may be separated by whitespace or
82: optional whitespace and exactly one
83: .Ql = ;
84: the latter format is useful to avoid the need to quote whitespace
85: when specifying configuration options using the
86: .Nm ssh ,
1.87 jmc 87: .Nm scp ,
1.1 stevesk 88: and
89: .Nm sftp
90: .Fl o
91: option.
1.88 dtucker 92: Arguments may optionally be enclosed in double quotes
93: .Pq \&"
94: in order to represent arguments containing spaces.
1.1 stevesk 95: .Pp
96: The possible
97: keywords and their meanings are as follows (note that
98: keywords are case-insensitive and arguments are case-sensitive):
99: .Bl -tag -width Ds
100: .It Cm Host
101: Restricts the following declarations (up to the next
102: .Cm Host
103: keyword) to be only for those hosts that match one of the patterns
104: given after the keyword.
1.112 krw 105: If more than one pattern is provided, they should be separated by whitespace.
1.1 stevesk 106: A single
1.83 jmc 107: .Ql *
1.1 stevesk 108: as a pattern can be used to provide global
109: defaults for all hosts.
110: The host is the
111: .Ar hostname
1.83 jmc 112: argument given on the command line (i.e. the name is not converted to
1.1 stevesk 113: a canonicalized host name before matching).
1.148 djm 114: .Pp
115: A pattern entry may be negated by prefixing it with an exclamation mark
116: .Pq Sq !\& .
117: If a negated entry is matched, then the
118: .Cm Host
119: entry is ignored, regardless of whether any other patterns on the line
120: match.
121: Negated matches are therefore useful to provide exceptions for wildcard
122: matches.
1.81 jmc 123: .Pp
124: See
125: .Sx PATTERNS
126: for more information on patterns.
1.10 djm 127: .It Cm AddressFamily
1.11 jmc 128: Specifies which address family to use when connecting.
129: Valid arguments are
1.10 djm 130: .Dq any ,
131: .Dq inet
1.84 jmc 132: (use IPv4 only), or
1.10 djm 133: .Dq inet6
1.40 jmc 134: (use IPv6 only).
1.1 stevesk 135: .It Cm BatchMode
136: If set to
137: .Dq yes ,
138: passphrase/password querying will be disabled.
139: This option is useful in scripts and other batch jobs where no user
140: is present to supply the password.
141: The argument must be
142: .Dq yes
143: or
144: .Dq no .
145: The default is
146: .Dq no .
147: .It Cm BindAddress
1.60 dtucker 148: Use the specified address on the local machine as the source address of
1.61 jmc 149: the connection.
150: Only useful on systems with more than one address.
1.1 stevesk 151: Note that this option does not work if
152: .Cm UsePrivilegedPort
153: is set to
154: .Dq yes .
155: .It Cm ChallengeResponseAuthentication
1.82 jmc 156: Specifies whether to use challenge-response authentication.
1.1 stevesk 157: The argument to this keyword must be
158: .Dq yes
159: or
160: .Dq no .
161: The default is
162: .Dq yes .
163: .It Cm CheckHostIP
164: If this flag is set to
165: .Dq yes ,
1.84 jmc 166: .Xr ssh 1
167: will additionally check the host IP address in the
1.1 stevesk 168: .Pa known_hosts
169: file.
170: This allows ssh to detect if a host key changed due to DNS spoofing.
1.107 grunk 171: If the option is set to
1.1 stevesk 172: .Dq no ,
173: the check will not be executed.
174: The default is
175: .Dq yes .
176: .It Cm Cipher
177: Specifies the cipher to use for encrypting the session
178: in protocol version 1.
179: Currently,
180: .Dq blowfish ,
181: .Dq 3des ,
182: and
183: .Dq des
184: are supported.
185: .Ar des
186: is only supported in the
1.84 jmc 187: .Xr ssh 1
1.1 stevesk 188: client for interoperability with legacy protocol 1 implementations
189: that do not support the
190: .Ar 3des
1.7 jmc 191: cipher.
192: Its use is strongly discouraged due to cryptographic weaknesses.
1.1 stevesk 193: The default is
194: .Dq 3des .
195: .It Cm Ciphers
196: Specifies the ciphers allowed for protocol version 2
197: in order of preference.
198: Multiple ciphers must be comma-separated.
1.35 dtucker 199: The supported ciphers are
200: .Dq 3des-cbc ,
201: .Dq aes128-cbc ,
202: .Dq aes192-cbc ,
203: .Dq aes256-cbc ,
204: .Dq aes128-ctr ,
205: .Dq aes192-ctr ,
206: .Dq aes256-ctr ,
1.161 markus 207: .Dq aes128-gcm@openssh.com ,
208: .Dq aes256-gcm@openssh.com ,
1.54 djm 209: .Dq arcfour128 ,
210: .Dq arcfour256 ,
1.35 dtucker 211: .Dq arcfour ,
212: .Dq blowfish-cbc ,
213: and
214: .Dq cast128-cbc .
1.84 jmc 215: The default is:
216: .Bd -literal -offset 3n
1.116 naddy 217: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
1.161 markus 218: aes128-gcm@openssh.com,aes256-gcm@openssh.com,
1.116 naddy 219: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
220: aes256-cbc,arcfour
1.1 stevesk 221: .Ed
222: .It Cm ClearAllForwardings
1.84 jmc 223: Specifies that all local, remote, and dynamic port forwardings
1.1 stevesk 224: specified in the configuration files or on the command line be
1.7 jmc 225: cleared.
226: This option is primarily useful when used from the
1.84 jmc 227: .Xr ssh 1
1.1 stevesk 228: command line to clear port forwardings set in
229: configuration files, and is automatically set by
230: .Xr scp 1
231: and
232: .Xr sftp 1 .
233: The argument must be
234: .Dq yes
235: or
236: .Dq no .
237: The default is
238: .Dq no .
239: .It Cm Compression
240: Specifies whether to use compression.
241: The argument must be
242: .Dq yes
243: or
244: .Dq no .
245: The default is
246: .Dq no .
247: .It Cm CompressionLevel
248: Specifies the compression level to use if compression is enabled.
249: The argument must be an integer from 1 (fast) to 9 (slow, best).
250: The default level is 6, which is good for most applications.
251: The meaning of the values is the same as in
252: .Xr gzip 1 .
253: Note that this option applies to protocol version 1 only.
254: .It Cm ConnectionAttempts
255: Specifies the number of tries (one per second) to make before exiting.
256: The argument must be an integer.
257: This may be useful in scripts if the connection sometimes fails.
258: The default is 1.
1.9 djm 259: .It Cm ConnectTimeout
1.84 jmc 260: Specifies the timeout (in seconds) used when connecting to the
261: SSH server, instead of using the default system TCP timeout.
1.11 jmc 262: This value is used only when the target is down or really unreachable,
263: not when it refuses the connection.
1.36 djm 264: .It Cm ControlMaster
265: Enables the sharing of multiple sessions over a single network connection.
266: When set to
1.84 jmc 267: .Dq yes ,
268: .Xr ssh 1
1.36 djm 269: will listen for connections on a control socket specified using the
270: .Cm ControlPath
271: argument.
272: Additional sessions can connect to this socket using the same
273: .Cm ControlPath
274: with
275: .Cm ControlMaster
276: set to
277: .Dq no
1.38 jmc 278: (the default).
1.64 jmc 279: These sessions will try to reuse the master instance's network connection
1.63 djm 280: rather than initiating new ones, but will fall back to connecting normally
281: if the control socket does not exist, or is not listening.
282: .Pp
1.37 djm 283: Setting this to
284: .Dq ask
1.84 jmc 285: will cause ssh
1.37 djm 286: to listen for control connections, but require confirmation using the
287: .Ev SSH_ASKPASS
288: program before they are accepted (see
289: .Xr ssh-add 1
1.38 jmc 290: for details).
1.51 jakob 291: If the
292: .Cm ControlPath
1.84 jmc 293: cannot be opened,
294: ssh will continue without connecting to a master instance.
1.58 djm 295: .Pp
296: X11 and
1.59 jmc 297: .Xr ssh-agent 1
1.58 djm 298: forwarding is supported over these multiplexed connections, however the
1.70 stevesk 299: display and agent forwarded will be the one belonging to the master
1.59 jmc 300: connection i.e. it is not possible to forward multiple displays or agents.
1.56 djm 301: .Pp
302: Two additional options allow for opportunistic multiplexing: try to use a
303: master connection but fall back to creating a new one if one does not already
304: exist.
305: These options are:
306: .Dq auto
307: and
308: .Dq autoask .
309: The latter requires confirmation like the
310: .Dq ask
311: option.
1.36 djm 312: .It Cm ControlPath
1.55 djm 313: Specify the path to the control socket used for connection sharing as described
314: in the
1.36 djm 315: .Cm ControlMaster
1.57 djm 316: section above or the string
317: .Dq none
318: to disable connection sharing.
1.55 djm 319: In the path,
1.147 djm 320: .Ql %L
321: will be substituted by the first component of the local host name,
1.77 djm 322: .Ql %l
1.147 djm 323: will be substituted by the local host name (including any domain name),
1.55 djm 324: .Ql %h
325: will be substituted by the target host name,
1.150 jmc 326: .Ql %n
327: will be substituted by the original target host name
328: specified on the command line,
1.55 djm 329: .Ql %p
1.147 djm 330: the port,
1.55 djm 331: .Ql %r
1.147 djm 332: by the remote login username, and
333: .Ql %u
334: by the username of the user running
335: .Xr ssh 1 .
1.56 djm 336: It is recommended that any
337: .Cm ControlPath
338: used for opportunistic connection sharing include
1.78 jmc 339: at least %h, %p, and %r.
1.56 djm 340: This ensures that shared connections are uniquely identified.
1.137 djm 341: .It Cm ControlPersist
342: When used in conjunction with
343: .Cm ControlMaster ,
344: specifies that the master connection should remain open
345: in the background (waiting for future client connections)
346: after the initial client connection has been closed.
347: If set to
348: .Dq no ,
349: then the master connection will not be placed into the background,
350: and will close as soon as the initial client connection is closed.
351: If set to
352: .Dq yes ,
353: then the master connection will remain in the background indefinitely
354: (until killed or closed via a mechanism such as the
355: .Xr ssh 1
356: .Dq Fl O No exit
357: option).
358: If set to a time in seconds, or a time in any of the formats documented in
359: .Xr sshd_config 5 ,
360: then the backgrounded master connection will automatically terminate
361: after it has remained idle (with no client connections) for the
362: specified time.
1.38 jmc 363: .It Cm DynamicForward
1.74 jmc 364: Specifies that a TCP port on the local machine be forwarded
1.38 jmc 365: over the secure channel, and the application
366: protocol is then used to determine where to connect to from the
367: remote machine.
1.62 djm 368: .Pp
369: The argument must be
370: .Sm off
371: .Oo Ar bind_address : Oc Ar port .
372: .Sm on
1.138 djm 373: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.62 djm 374: By default, the local port is bound in accordance with the
375: .Cm GatewayPorts
376: setting.
377: However, an explicit
378: .Ar bind_address
379: may be used to bind the connection to a specific address.
380: The
381: .Ar bind_address
382: of
383: .Dq localhost
384: indicates that the listening port be bound for local use only, while an
385: empty address or
386: .Sq *
387: indicates that the port should be available from all interfaces.
388: .Pp
1.38 jmc 389: Currently the SOCKS4 and SOCKS5 protocols are supported, and
1.84 jmc 390: .Xr ssh 1
1.38 jmc 391: will act as a SOCKS server.
392: Multiple forwardings may be specified, and
393: additional forwardings can be given on the command line.
394: Only the superuser can forward privileged ports.
1.14 markus 395: .It Cm EnableSSHKeysign
396: Setting this option to
397: .Dq yes
398: in the global client configuration file
399: .Pa /etc/ssh/ssh_config
400: enables the use of the helper program
401: .Xr ssh-keysign 8
402: during
403: .Cm HostbasedAuthentication .
404: The argument must be
405: .Dq yes
406: or
407: .Dq no .
408: The default is
409: .Dq no .
1.23 jmc 410: This option should be placed in the non-hostspecific section.
1.14 markus 411: See
412: .Xr ssh-keysign 8
413: for more information.
1.1 stevesk 414: .It Cm EscapeChar
415: Sets the escape character (default:
416: .Ql ~ ) .
417: The escape character can also
418: be set on the command line.
419: The argument should be a single character,
420: .Ql ^
421: followed by a letter, or
422: .Dq none
423: to disable the escape
424: character entirely (making the connection transparent for binary
425: data).
1.96 markus 426: .It Cm ExitOnForwardFailure
427: Specifies whether
428: .Xr ssh 1
429: should terminate the connection if it cannot set up all requested
1.102 stevesk 430: dynamic, tunnel, local, and remote port forwardings.
1.96 markus 431: The argument must be
432: .Dq yes
433: or
434: .Dq no .
435: The default is
436: .Dq no .
1.1 stevesk 437: .It Cm ForwardAgent
438: Specifies whether the connection to the authentication agent (if any)
439: will be forwarded to the remote machine.
440: The argument must be
441: .Dq yes
442: or
443: .Dq no .
444: The default is
445: .Dq no .
1.3 stevesk 446: .Pp
1.7 jmc 447: Agent forwarding should be enabled with caution.
448: Users with the ability to bypass file permissions on the remote host
449: (for the agent's Unix-domain socket)
450: can access the local agent through the forwarded connection.
451: An attacker cannot obtain key material from the agent,
1.3 stevesk 452: however they can perform operations on the keys that enable them to
453: authenticate using the identities loaded into the agent.
1.1 stevesk 454: .It Cm ForwardX11
455: Specifies whether X11 connections will be automatically redirected
456: over the secure channel and
457: .Ev DISPLAY
458: set.
459: The argument must be
460: .Dq yes
461: or
462: .Dq no .
463: The default is
464: .Dq no .
1.3 stevesk 465: .Pp
1.7 jmc 466: X11 forwarding should be enabled with caution.
467: Users with the ability to bypass file permissions on the remote host
1.22 markus 468: (for the user's X11 authorization database)
1.7 jmc 469: can access the local X11 display through the forwarded connection.
1.22 markus 470: An attacker may then be able to perform activities such as keystroke monitoring
471: if the
472: .Cm ForwardX11Trusted
473: option is also enabled.
1.134 djm 474: .It Cm ForwardX11Timeout
1.135 jmc 475: Specify a timeout for untrusted X11 forwarding
476: using the format described in the
1.166 jmc 477: TIME FORMATS section of
1.134 djm 478: .Xr sshd_config 5 .
479: X11 connections received by
480: .Xr ssh 1
481: after this time will be refused.
482: The default is to disable untrusted X11 forwarding after twenty minutes has
483: elapsed.
1.22 markus 484: .It Cm ForwardX11Trusted
1.34 jmc 485: If this option is set to
1.84 jmc 486: .Dq yes ,
487: remote X11 clients will have full access to the original X11 display.
1.42 djm 488: .Pp
1.22 markus 489: If this option is set to
1.84 jmc 490: .Dq no ,
491: remote X11 clients will be considered untrusted and prevented
1.22 markus 492: from stealing or tampering with data belonging to trusted X11
493: clients.
1.42 djm 494: Furthermore, the
495: .Xr xauth 1
496: token used for the session will be set to expire after 20 minutes.
497: Remote clients will be refused access after this time.
1.22 markus 498: .Pp
499: The default is
500: .Dq no .
501: .Pp
502: See the X11 SECURITY extension specification for full details on
503: the restrictions imposed on untrusted clients.
1.1 stevesk 504: .It Cm GatewayPorts
505: Specifies whether remote hosts are allowed to connect to local
506: forwarded ports.
507: By default,
1.84 jmc 508: .Xr ssh 1
1.7 jmc 509: binds local port forwardings to the loopback address.
510: This prevents other remote hosts from connecting to forwarded ports.
1.1 stevesk 511: .Cm GatewayPorts
1.84 jmc 512: can be used to specify that ssh
1.1 stevesk 513: should bind local port forwardings to the wildcard address,
514: thus allowing remote hosts to connect to forwarded ports.
515: The argument must be
516: .Dq yes
517: or
518: .Dq no .
519: The default is
520: .Dq no .
521: .It Cm GlobalKnownHostsFile
1.151 djm 522: Specifies one or more files to use for the global
523: host key database, separated by whitespace.
524: The default is
525: .Pa /etc/ssh/ssh_known_hosts ,
526: .Pa /etc/ssh/ssh_known_hosts2 .
1.18 markus 527: .It Cm GSSAPIAuthentication
1.27 markus 528: Specifies whether user authentication based on GSSAPI is allowed.
1.20 jmc 529: The default is
1.21 markus 530: .Dq no .
1.18 markus 531: Note that this option applies to protocol version 2 only.
532: .It Cm GSSAPIDelegateCredentials
533: Forward (delegate) credentials to the server.
534: The default is
535: .Dq no .
536: Note that this option applies to protocol version 2 only.
1.44 djm 537: .It Cm HashKnownHosts
538: Indicates that
1.84 jmc 539: .Xr ssh 1
1.44 djm 540: should hash host names and addresses when they are added to
1.50 djm 541: .Pa ~/.ssh/known_hosts .
1.44 djm 542: These hashed names may be used normally by
1.84 jmc 543: .Xr ssh 1
1.44 djm 544: and
1.84 jmc 545: .Xr sshd 8 ,
1.44 djm 546: but they do not reveal identifying information should the file's contents
547: be disclosed.
548: The default is
549: .Dq no .
1.97 jmc 550: Note that existing names and addresses in known hosts files
551: will not be converted automatically,
552: but may be manually hashed using
1.45 djm 553: .Xr ssh-keygen 1 .
1.1 stevesk 554: .It Cm HostbasedAuthentication
555: Specifies whether to try rhosts based authentication with public key
556: authentication.
557: The argument must be
558: .Dq yes
559: or
560: .Dq no .
561: The default is
562: .Dq no .
563: This option applies to protocol version 2 only and
564: is similar to
565: .Cm RhostsRSAAuthentication .
566: .It Cm HostKeyAlgorithms
567: Specifies the protocol version 2 host key algorithms
568: that the client wants to use in order of preference.
569: The default for this option is:
1.139 djm 570: .Bd -literal -offset 3n
571: ecdsa-sha2-nistp256-cert-v01@openssh.com,
572: ecdsa-sha2-nistp384-cert-v01@openssh.com,
573: ecdsa-sha2-nistp521-cert-v01@openssh.com,
574: ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,
575: ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,
576: ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
577: ssh-rsa,ssh-dss
578: .Ed
1.145 djm 579: .Pp
580: If hostkeys are known for the destination host then this default is modified
581: to prefer their algorithms.
1.1 stevesk 582: .It Cm HostKeyAlias
583: Specifies an alias that should be used instead of the
584: real host name when looking up or saving the host key
585: in the host key database files.
1.84 jmc 586: This option is useful for tunneling SSH connections
1.1 stevesk 587: or for multiple servers running on a single host.
588: .It Cm HostName
589: Specifies the real host name to log into.
590: This can be used to specify nicknames or abbreviations for hosts.
1.136 djm 591: If the hostname contains the character sequence
592: .Ql %h ,
1.150 jmc 593: then this will be replaced with the host name specified on the command line
1.136 djm 594: (this is useful for manipulating unqualified names).
1.84 jmc 595: The default is the name given on the command line.
1.1 stevesk 596: Numeric IP addresses are also permitted (both on the command line and in
597: .Cm HostName
598: specifications).
1.29 markus 599: .It Cm IdentitiesOnly
600: Specifies that
1.84 jmc 601: .Xr ssh 1
1.29 markus 602: should only use the authentication identity files configured in the
1.31 jmc 603: .Nm
1.29 markus 604: files,
1.84 jmc 605: even if
606: .Xr ssh-agent 1
1.159 djm 607: or a
608: .Cm PKCS11Provider
1.29 markus 609: offers more identities.
610: The argument to this keyword must be
611: .Dq yes
612: or
613: .Dq no .
1.84 jmc 614: This option is intended for situations where ssh-agent
1.29 markus 615: offers many different identities.
616: The default is
617: .Dq no .
1.67 jmc 618: .It Cm IdentityFile
1.155 dtucker 619: Specifies a file from which the user's DSA, ECDSA or RSA authentication
1.139 djm 620: identity is read.
1.67 jmc 621: The default is
622: .Pa ~/.ssh/identity
623: for protocol version 1, and
1.139 djm 624: .Pa ~/.ssh/id_dsa ,
625: .Pa ~/.ssh/id_ecdsa
626: and
1.67 jmc 627: .Pa ~/.ssh/id_rsa
628: for protocol version 2.
629: Additionally, any identities represented by the authentication agent
1.165 djm 630: will be used for authentication unless
631: .Cm IdentitiesOnly
632: is set.
1.129 djm 633: .Xr ssh 1
634: will try to load certificate information from the filename obtained by
635: appending
636: .Pa -cert.pub
637: to the path of a specified
638: .Cm IdentityFile .
1.90 djm 639: .Pp
1.67 jmc 640: The file name may use the tilde
1.91 jmc 641: syntax to refer to a user's home directory or one of the following
1.90 djm 642: escape characters:
643: .Ql %d
644: (local user's home directory),
645: .Ql %u
646: (local user name),
647: .Ql %l
648: (local host name),
649: .Ql %h
650: (remote host name) or
1.92 djm 651: .Ql %r
1.90 djm 652: (remote user name).
653: .Pp
1.67 jmc 654: It is possible to have
655: multiple identity files specified in configuration files; all these
656: identities will be tried in sequence.
1.152 djm 657: Multiple
658: .Cm IdentityFile
659: directives will add to the list of identities tried (this behaviour
660: differs from that of other configuration directives).
1.165 djm 661: .Pp
662: .Cm IdentityFile
663: may be used in conjunction with
664: .Cm IdentitiesOnly
665: to select which identities in an agent are offered during authentication.
1.164 jmc 666: .It Cm IgnoreUnknown
667: Specifies a pattern-list of unknown options to be ignored if they are
668: encountered in configuration parsing.
669: This may be used to suppress errors if
670: .Nm
671: contains options that are unrecognised by
672: .Xr ssh 1 .
673: It is recommended that
674: .Cm IgnoreUnknown
675: be listed early in the configuration file as it will not be applied
676: to unknown options that appear before it.
1.143 djm 677: .It Cm IPQoS
678: Specifies the IPv4 type-of-service or DSCP class for connections.
679: Accepted values are
680: .Dq af11 ,
681: .Dq af12 ,
682: .Dq af13 ,
1.154 djm 683: .Dq af21 ,
1.143 djm 684: .Dq af22 ,
685: .Dq af23 ,
686: .Dq af31 ,
687: .Dq af32 ,
688: .Dq af33 ,
689: .Dq af41 ,
690: .Dq af42 ,
691: .Dq af43 ,
692: .Dq cs0 ,
693: .Dq cs1 ,
694: .Dq cs2 ,
695: .Dq cs3 ,
696: .Dq cs4 ,
697: .Dq cs5 ,
698: .Dq cs6 ,
699: .Dq cs7 ,
700: .Dq ef ,
701: .Dq lowdelay ,
702: .Dq throughput ,
703: .Dq reliability ,
704: or a numeric value.
1.146 djm 705: This option may take one or two arguments, separated by whitespace.
1.143 djm 706: If one argument is specified, it is used as the packet class unconditionally.
707: If two values are specified, the first is automatically selected for
708: interactive sessions and the second for non-interactive sessions.
709: The default is
710: .Dq lowdelay
711: for interactive sessions and
712: .Dq throughput
713: for non-interactive sessions.
1.103 djm 714: .It Cm KbdInteractiveAuthentication
715: Specifies whether to use keyboard-interactive authentication.
716: The argument to this keyword must be
717: .Dq yes
718: or
719: .Dq no .
720: The default is
721: .Dq yes .
1.39 djm 722: .It Cm KbdInteractiveDevices
723: Specifies the list of methods to use in keyboard-interactive authentication.
724: Multiple method names must be comma-separated.
725: The default is to use the server specified list.
1.85 jmc 726: The methods available vary depending on what the server supports.
727: For an OpenSSH server,
728: it may be zero or more of:
729: .Dq bsdauth ,
730: .Dq pam ,
731: and
732: .Dq skey .
1.140 djm 733: .It Cm KexAlgorithms
734: Specifies the available KEX (Key Exchange) algorithms.
735: Multiple algorithms must be comma-separated.
1.141 jmc 736: The default is:
737: .Bd -literal -offset indent
738: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
739: diffie-hellman-group-exchange-sha256,
740: diffie-hellman-group-exchange-sha1,
741: diffie-hellman-group14-sha1,
742: diffie-hellman-group1-sha1
743: .Ed
1.65 reyk 744: .It Cm LocalCommand
745: Specifies a command to execute on the local machine after successfully
746: connecting to the server.
747: The command string extends to the end of the line, and is executed with
1.105 jmc 748: the user's shell.
1.109 dtucker 749: The following escape character substitutions will be performed:
750: .Ql %d
751: (local user's home directory),
752: .Ql %h
753: (remote host name),
754: .Ql %l
755: (local host name),
756: .Ql %n
757: (host name as provided on the command line),
758: .Ql %p
759: (remote port),
760: .Ql %r
761: (remote user name) or
762: .Ql %u
763: (local user name).
1.123 djm 764: .Pp
765: The command is run synchronously and does not have access to the
766: session of the
767: .Xr ssh 1
768: that spawned it.
769: It should not be used for interactive commands.
770: .Pp
1.65 reyk 771: This directive is ignored unless
772: .Cm PermitLocalCommand
773: has been enabled.
1.1 stevesk 774: .It Cm LocalForward
1.74 jmc 775: Specifies that a TCP port on the local machine be forwarded over
1.1 stevesk 776: the secure channel to the specified host and port from the remote machine.
1.49 jmc 777: The first argument must be
1.43 djm 778: .Sm off
1.49 jmc 779: .Oo Ar bind_address : Oc Ar port
1.43 djm 780: .Sm on
1.49 jmc 781: and the second argument must be
782: .Ar host : Ns Ar hostport .
1.138 djm 783: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.46 jmc 784: Multiple forwardings may be specified, and additional forwardings can be
1.43 djm 785: given on the command line.
1.1 stevesk 786: Only the superuser can forward privileged ports.
1.43 djm 787: By default, the local port is bound in accordance with the
788: .Cm GatewayPorts
789: setting.
790: However, an explicit
791: .Ar bind_address
792: may be used to bind the connection to a specific address.
793: The
794: .Ar bind_address
795: of
796: .Dq localhost
1.46 jmc 797: indicates that the listening port be bound for local use only, while an
798: empty address or
799: .Sq *
1.43 djm 800: indicates that the port should be available from all interfaces.
1.1 stevesk 801: .It Cm LogLevel
802: Gives the verbosity level that is used when logging messages from
1.84 jmc 803: .Xr ssh 1 .
1.1 stevesk 804: The possible values are:
1.84 jmc 805: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.
1.7 jmc 806: The default is INFO.
807: DEBUG and DEBUG1 are equivalent.
808: DEBUG2 and DEBUG3 each specify higher levels of verbose output.
1.1 stevesk 809: .It Cm MACs
810: Specifies the MAC (message authentication code) algorithms
811: in order of preference.
812: The MAC algorithm is used in protocol version 2
813: for data integrity protection.
814: Multiple algorithms must be comma-separated.
1.160 markus 815: The algorithms that contain
816: .Dq -etm
817: calculate the MAC after encryption (encrypt-then-mac).
818: These are considered safer and their use recommended.
1.84 jmc 819: The default is:
1.101 jmc 820: .Bd -literal -offset indent
1.160 markus 821: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,
822: umac-64-etm@openssh.com,umac-128-etm@openssh.com,
823: hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,
824: hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,
825: hmac-md5-96-etm@openssh.com,
1.158 markus 826: hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,
1.157 naddy 827: hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,
828: hmac-sha1-96,hmac-md5-96
1.101 jmc 829: .Ed
1.1 stevesk 830: .It Cm NoHostAuthenticationForLocalhost
831: This option can be used if the home directory is shared across machines.
832: In this case localhost will refer to a different machine on each of
833: the machines and the user will get many warnings about changed host keys.
834: However, this option disables host authentication for localhost.
835: The argument to this keyword must be
836: .Dq yes
837: or
838: .Dq no .
839: The default is to check the host key for localhost.
840: .It Cm NumberOfPasswordPrompts
841: Specifies the number of password prompts before giving up.
842: The argument to this keyword must be an integer.
1.84 jmc 843: The default is 3.
1.1 stevesk 844: .It Cm PasswordAuthentication
845: Specifies whether to use password authentication.
846: The argument to this keyword must be
847: .Dq yes
848: or
849: .Dq no .
850: The default is
851: .Dq yes .
1.65 reyk 852: .It Cm PermitLocalCommand
853: Allow local command execution via the
854: .Ic LocalCommand
855: option or using the
1.66 jmc 856: .Ic !\& Ns Ar command
1.65 reyk 857: escape sequence in
858: .Xr ssh 1 .
859: The argument must be
860: .Dq yes
861: or
862: .Dq no .
863: The default is
864: .Dq no .
1.127 markus 865: .It Cm PKCS11Provider
866: Specifies which PKCS#11 provider to use.
1.144 jmc 867: The argument to this keyword is the PKCS#11 shared library
1.127 markus 868: .Xr ssh 1
1.128 markus 869: should use to communicate with a PKCS#11 token providing the user's
1.127 markus 870: private RSA key.
1.67 jmc 871: .It Cm Port
872: Specifies the port number to connect on the remote host.
1.84 jmc 873: The default is 22.
1.1 stevesk 874: .It Cm PreferredAuthentications
875: Specifies the order in which the client should try protocol 2
1.11 jmc 876: authentication methods.
1.48 jmc 877: This allows a client to prefer one method (e.g.\&
1.1 stevesk 878: .Cm keyboard-interactive )
1.48 jmc 879: over another method (e.g.\&
1.131 jmc 880: .Cm password ) .
881: The default is:
882: .Bd -literal -offset indent
883: gssapi-with-mic,hostbased,publickey,
884: keyboard-interactive,password
885: .Ed
1.1 stevesk 886: .It Cm Protocol
887: Specifies the protocol versions
1.84 jmc 888: .Xr ssh 1
1.1 stevesk 889: should support in order of preference.
890: The possible values are
1.84 jmc 891: .Sq 1
1.1 stevesk 892: and
1.84 jmc 893: .Sq 2 .
1.1 stevesk 894: Multiple versions must be comma-separated.
1.120 markus 895: When this option is set to
1.121 jmc 896: .Dq 2,1
1.120 markus 897: .Nm ssh
898: will try version 2 and fall back to version 1
899: if version 2 is not available.
1.1 stevesk 900: The default is
1.121 jmc 901: .Sq 2 .
1.1 stevesk 902: .It Cm ProxyCommand
903: Specifies the command to use to connect to the server.
904: The command
905: string extends to the end of the line, and is executed with
1.105 jmc 906: the user's shell.
1.133 jmc 907: In the command string, any occurrence of
1.1 stevesk 908: .Ql %h
909: will be substituted by the host name to
1.132 djm 910: connect,
1.1 stevesk 911: .Ql %p
1.133 jmc 912: by the port, and
913: .Ql %r
1.132 djm 914: by the remote user name.
1.1 stevesk 915: The command can be basically anything,
916: and should read from its standard input and write to its standard output.
917: It should eventually connect an
918: .Xr sshd 8
919: server running on some machine, or execute
920: .Ic sshd -i
921: somewhere.
922: Host key management will be done using the
923: HostName of the host being connected (defaulting to the name typed by
924: the user).
1.7 jmc 925: Setting the command to
926: .Dq none
1.6 markus 927: disables this option entirely.
1.1 stevesk 928: Note that
929: .Cm CheckHostIP
930: is not available for connects with a proxy command.
1.52 djm 931: .Pp
932: This directive is useful in conjunction with
933: .Xr nc 1
934: and its proxy support.
1.53 jmc 935: For example, the following directive would connect via an HTTP proxy at
1.52 djm 936: 192.0.2.0:
937: .Bd -literal -offset 3n
938: ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p
939: .Ed
1.167 djm 940: .It Cm ProxyUseFdpass
1.168 ! jmc 941: Specifies that
1.167 djm 942: .Cm ProxyCommand
943: will pass a connected file descriptor back to
1.168 ! jmc 944: .Xr ssh 1
1.167 djm 945: instead of continuing to execute and pass data.
946: The default is
947: .Dq no .
1.1 stevesk 948: .It Cm PubkeyAuthentication
949: Specifies whether to try public key authentication.
950: The argument to this keyword must be
951: .Dq yes
952: or
953: .Dq no .
954: The default is
955: .Dq yes .
956: This option applies to protocol version 2 only.
1.75 dtucker 957: .It Cm RekeyLimit
958: Specifies the maximum amount of data that may be transmitted before the
1.162 dtucker 959: session key is renegotiated, optionally followed a maximum amount of
960: time that may pass before the session key is renegotiated.
961: The first argument is specified in bytes and may have a suffix of
1.76 jmc 962: .Sq K ,
963: .Sq M ,
1.75 dtucker 964: or
1.76 jmc 965: .Sq G
1.75 dtucker 966: to indicate Kilobytes, Megabytes, or Gigabytes, respectively.
967: The default is between
1.84 jmc 968: .Sq 1G
1.75 dtucker 969: and
1.84 jmc 970: .Sq 4G ,
1.75 dtucker 971: depending on the cipher.
1.162 dtucker 972: The optional second value is specified in seconds and may use any of the
973: units documented in the
1.166 jmc 974: TIME FORMATS section of
1.162 dtucker 975: .Xr sshd_config 5 .
976: The default value for
977: .Cm RekeyLimit
978: is
979: .Dq default none ,
980: which means that rekeying is performed after the cipher's default amount
981: of data has been sent or received and no time based rekeying is done.
1.76 jmc 982: This option applies to protocol version 2 only.
1.1 stevesk 983: .It Cm RemoteForward
1.74 jmc 984: Specifies that a TCP port on the remote machine be forwarded over
1.1 stevesk 985: the secure channel to the specified host and port from the local machine.
1.49 jmc 986: The first argument must be
1.43 djm 987: .Sm off
1.49 jmc 988: .Oo Ar bind_address : Oc Ar port
1.43 djm 989: .Sm on
1.49 jmc 990: and the second argument must be
991: .Ar host : Ns Ar hostport .
1.138 djm 992: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.1 stevesk 993: Multiple forwardings may be specified, and additional
994: forwardings can be given on the command line.
1.113 stevesk 995: Privileged ports can be forwarded only when
996: logging in as root on the remote machine.
1.118 jmc 997: .Pp
1.117 djm 998: If the
999: .Ar port
1000: argument is
1001: .Ql 0 ,
1002: the listen port will be dynamically allocated on the server and reported
1003: to the client at run time.
1.43 djm 1004: .Pp
1005: If the
1006: .Ar bind_address
1007: is not specified, the default is to only bind to loopback addresses.
1008: If the
1009: .Ar bind_address
1010: is
1011: .Ql *
1012: or an empty string, then the forwarding is requested to listen on all
1013: interfaces.
1014: Specifying a remote
1015: .Ar bind_address
1.46 jmc 1016: will only succeed if the server's
1017: .Cm GatewayPorts
1.43 djm 1018: option is enabled (see
1.46 jmc 1019: .Xr sshd_config 5 ) .
1.149 djm 1020: .It Cm RequestTTY
1021: Specifies whether to request a pseudo-tty for the session.
1022: The argument may be one of:
1023: .Dq no
1024: (never request a TTY),
1025: .Dq yes
1026: (always request a TTY when standard input is a TTY),
1027: .Dq force
1028: (always request a TTY) or
1029: .Dq auto
1030: (request a TTY when opening a login session).
1031: This option mirrors the
1032: .Fl t
1033: and
1034: .Fl T
1035: flags for
1036: .Xr ssh 1 .
1.1 stevesk 1037: .It Cm RhostsRSAAuthentication
1038: Specifies whether to try rhosts based authentication with RSA host
1039: authentication.
1040: The argument must be
1041: .Dq yes
1042: or
1043: .Dq no .
1044: The default is
1045: .Dq no .
1046: This option applies to protocol version 1 only and requires
1.84 jmc 1047: .Xr ssh 1
1.1 stevesk 1048: to be setuid root.
1049: .It Cm RSAAuthentication
1050: Specifies whether to try RSA authentication.
1051: The argument to this keyword must be
1052: .Dq yes
1053: or
1054: .Dq no .
1055: RSA authentication will only be
1056: attempted if the identity file exists, or an authentication agent is
1057: running.
1058: The default is
1059: .Dq yes .
1060: Note that this option applies to protocol version 1 only.
1.32 djm 1061: .It Cm SendEnv
1062: Specifies what variables from the local
1063: .Xr environ 7
1064: should be sent to the server.
1.84 jmc 1065: Note that environment passing is only supported for protocol 2.
1066: The server must also support it, and the server must be configured to
1.33 djm 1067: accept these environment variables.
1.32 djm 1068: Refer to
1069: .Cm AcceptEnv
1070: in
1071: .Xr sshd_config 5
1072: for how to configure the server.
1.80 jmc 1073: Variables are specified by name, which may contain wildcard characters.
1.33 djm 1074: Multiple environment variables may be separated by whitespace or spread
1.32 djm 1075: across multiple
1076: .Cm SendEnv
1077: directives.
1078: The default is not to send any environment variables.
1.81 jmc 1079: .Pp
1080: See
1081: .Sx PATTERNS
1082: for more information on patterns.
1.28 markus 1083: .It Cm ServerAliveCountMax
1.73 jmc 1084: Sets the number of server alive messages (see below) which may be
1.28 markus 1085: sent without
1.84 jmc 1086: .Xr ssh 1
1.28 markus 1087: receiving any messages back from the server.
1088: If this threshold is reached while server alive messages are being sent,
1.84 jmc 1089: ssh will disconnect from the server, terminating the session.
1.28 markus 1090: It is important to note that the use of server alive messages is very
1091: different from
1092: .Cm TCPKeepAlive
1093: (below).
1094: The server alive messages are sent through the encrypted channel
1095: and therefore will not be spoofable.
1096: The TCP keepalive option enabled by
1097: .Cm TCPKeepAlive
1098: is spoofable.
1099: The server alive mechanism is valuable when the client or
1100: server depend on knowing when a connection has become inactive.
1101: .Pp
1102: The default value is 3.
1103: If, for example,
1104: .Cm ServerAliveInterval
1.84 jmc 1105: (see below) is set to 15 and
1.28 markus 1106: .Cm ServerAliveCountMax
1.84 jmc 1107: is left at the default, if the server becomes unresponsive,
1108: ssh will disconnect after approximately 45 seconds.
1.89 markus 1109: This option applies to protocol version 2 only.
1.67 jmc 1110: .It Cm ServerAliveInterval
1111: Sets a timeout interval in seconds after which if no data has been received
1112: from the server,
1.84 jmc 1113: .Xr ssh 1
1.67 jmc 1114: will send a message through the encrypted
1115: channel to request a response from the server.
1116: The default
1117: is 0, indicating that these messages will not be sent to the server.
1118: This option applies to protocol version 2 only.
1.1 stevesk 1119: .It Cm StrictHostKeyChecking
1120: If this flag is set to
1121: .Dq yes ,
1.84 jmc 1122: .Xr ssh 1
1.1 stevesk 1123: will never automatically add host keys to the
1.50 djm 1124: .Pa ~/.ssh/known_hosts
1.1 stevesk 1125: file, and refuses to connect to hosts whose host key has changed.
1126: This provides maximum protection against trojan horse attacks,
1.84 jmc 1127: though it can be annoying when the
1.1 stevesk 1128: .Pa /etc/ssh/ssh_known_hosts
1.84 jmc 1129: file is poorly maintained or when connections to new hosts are
1.1 stevesk 1130: frequently made.
1131: This option forces the user to manually
1132: add all new hosts.
1133: If this flag is set to
1134: .Dq no ,
1.84 jmc 1135: ssh will automatically add new host keys to the
1.1 stevesk 1136: user known hosts files.
1137: If this flag is set to
1138: .Dq ask ,
1139: new host keys
1140: will be added to the user known host files only after the user
1141: has confirmed that is what they really want to do, and
1.84 jmc 1142: ssh will refuse to connect to hosts whose host key has changed.
1.1 stevesk 1143: The host keys of
1144: known hosts will be verified automatically in all cases.
1145: The argument must be
1146: .Dq yes ,
1.84 jmc 1147: .Dq no ,
1.1 stevesk 1148: or
1149: .Dq ask .
1150: The default is
1151: .Dq ask .
1.26 markus 1152: .It Cm TCPKeepAlive
1153: Specifies whether the system should send TCP keepalive messages to the
1154: other side.
1155: If they are sent, death of the connection or crash of one
1156: of the machines will be properly noticed.
1157: However, this means that
1158: connections will die if the route is down temporarily, and some people
1159: find it annoying.
1160: .Pp
1161: The default is
1162: .Dq yes
1163: (to send TCP keepalive messages), and the client will notice
1164: if the network goes down or the remote host dies.
1165: This is important in scripts, and many users want it too.
1166: .Pp
1167: To disable TCP keepalive messages, the value should be set to
1168: .Dq no .
1.65 reyk 1169: .It Cm Tunnel
1.95 stevesk 1170: Request
1.65 reyk 1171: .Xr tun 4
1.69 jmc 1172: device forwarding between the client and the server.
1.65 reyk 1173: The argument must be
1.68 reyk 1174: .Dq yes ,
1.95 stevesk 1175: .Dq point-to-point
1176: (layer 3),
1177: .Dq ethernet
1178: (layer 2),
1.65 reyk 1179: or
1180: .Dq no .
1.95 stevesk 1181: Specifying
1182: .Dq yes
1183: requests the default tunnel mode, which is
1184: .Dq point-to-point .
1.65 reyk 1185: The default is
1186: .Dq no .
1187: .It Cm TunnelDevice
1.95 stevesk 1188: Specifies the
1.65 reyk 1189: .Xr tun 4
1.95 stevesk 1190: devices to open on the client
1191: .Pq Ar local_tun
1192: and the server
1193: .Pq Ar remote_tun .
1194: .Pp
1195: The argument must be
1196: .Sm off
1197: .Ar local_tun Op : Ar remote_tun .
1198: .Sm on
1199: The devices may be specified by numerical ID or the keyword
1200: .Dq any ,
1201: which uses the next available tunnel device.
1202: If
1203: .Ar remote_tun
1204: is not specified, it defaults to
1205: .Dq any .
1206: The default is
1207: .Dq any:any .
1.72 jmc 1208: .It Cm UsePrivilegedPort
1209: Specifies whether to use a privileged port for outgoing connections.
1210: The argument must be
1211: .Dq yes
1212: or
1213: .Dq no .
1214: The default is
1215: .Dq no .
1216: If set to
1.84 jmc 1217: .Dq yes ,
1218: .Xr ssh 1
1.72 jmc 1219: must be setuid root.
1220: Note that this option must be set to
1221: .Dq yes
1222: for
1223: .Cm RhostsRSAAuthentication
1224: with older servers.
1.1 stevesk 1225: .It Cm User
1226: Specifies the user to log in as.
1227: This can be useful when a different user name is used on different machines.
1228: This saves the trouble of
1229: having to remember to give the user name on the command line.
1230: .It Cm UserKnownHostsFile
1.151 djm 1231: Specifies one or more files to use for the user
1232: host key database, separated by whitespace.
1233: The default is
1234: .Pa ~/.ssh/known_hosts ,
1235: .Pa ~/.ssh/known_hosts2 .
1.8 jakob 1236: .It Cm VerifyHostKeyDNS
1237: Specifies whether to verify the remote key using DNS and SSHFP resource
1238: records.
1.24 jakob 1239: If this option is set to
1240: .Dq yes ,
1.25 jmc 1241: the client will implicitly trust keys that match a secure fingerprint
1.24 jakob 1242: from DNS.
1243: Insecure fingerprints will be handled as if this option was set to
1244: .Dq ask .
1245: If this option is set to
1246: .Dq ask ,
1247: information on fingerprint match will be displayed, but the user will still
1248: need to confirm new host keys according to the
1249: .Cm StrictHostKeyChecking
1250: option.
1251: The argument must be
1252: .Dq yes ,
1.84 jmc 1253: .Dq no ,
1.25 jmc 1254: or
1255: .Dq ask .
1.8 jakob 1256: The default is
1257: .Dq no .
1.12 jakob 1258: Note that this option applies to protocol version 2 only.
1.84 jmc 1259: .Pp
1.166 jmc 1260: See also VERIFYING HOST KEYS in
1.84 jmc 1261: .Xr ssh 1 .
1.111 grunk 1262: .It Cm VisualHostKey
1263: If this flag is set to
1264: .Dq yes ,
1265: an ASCII art representation of the remote host key fingerprint is
1.114 stevesk 1266: printed in addition to the hex fingerprint string at login and
1267: for unknown host keys.
1.111 grunk 1268: If this flag is set to
1269: .Dq no ,
1.114 stevesk 1270: no fingerprint strings are printed at login and
1271: only the hex fingerprint string will be printed for unknown host keys.
1.111 grunk 1272: The default is
1273: .Dq no .
1.1 stevesk 1274: .It Cm XAuthLocation
1.5 stevesk 1275: Specifies the full pathname of the
1.1 stevesk 1276: .Xr xauth 1
1277: program.
1278: The default is
1279: .Pa /usr/X11R6/bin/xauth .
1280: .El
1.86 jmc 1281: .Sh PATTERNS
1282: A
1283: .Em pattern
1284: consists of zero or more non-whitespace characters,
1285: .Sq *
1286: (a wildcard that matches zero or more characters),
1287: or
1288: .Sq ?\&
1289: (a wildcard that matches exactly one character).
1290: For example, to specify a set of declarations for any host in the
1291: .Dq .co.uk
1292: set of domains,
1293: the following pattern could be used:
1294: .Pp
1295: .Dl Host *.co.uk
1296: .Pp
1297: The following pattern
1298: would match any host in the 192.168.0.[0-9] network range:
1299: .Pp
1300: .Dl Host 192.168.0.?
1301: .Pp
1302: A
1303: .Em pattern-list
1304: is a comma-separated list of patterns.
1305: Patterns within pattern-lists may be negated
1306: by preceding them with an exclamation mark
1307: .Pq Sq !\& .
1308: For example,
1309: to allow a key to be used from anywhere within an organisation
1310: except from the
1311: .Dq dialup
1312: pool,
1313: the following entry (in authorized_keys) could be used:
1314: .Pp
1315: .Dl from=\&"!*.dialup.example.com,*.example.com\&"
1.1 stevesk 1316: .Sh FILES
1317: .Bl -tag -width Ds
1.50 djm 1318: .It Pa ~/.ssh/config
1.1 stevesk 1319: This is the per-user configuration file.
1320: The format of this file is described above.
1.84 jmc 1321: This file is used by the SSH client.
1.30 djm 1322: Because of the potential for abuse, this file must have strict permissions:
1323: read/write for the user, and not accessible by others.
1.1 stevesk 1324: .It Pa /etc/ssh/ssh_config
1325: Systemwide configuration file.
1326: This file provides defaults for those
1327: values that are not specified in the user's configuration file, and
1328: for those users who do not have a configuration file.
1329: This file must be world-readable.
1330: .El
1.13 jmc 1331: .Sh SEE ALSO
1332: .Xr ssh 1
1.1 stevesk 1333: .Sh AUTHORS
1334: OpenSSH is a derivative of the original and free
1335: ssh 1.2.12 release by Tatu Ylonen.
1336: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1337: Theo de Raadt and Dug Song
1338: removed many bugs, re-added newer features and
1339: created OpenSSH.
1340: Markus Friedl contributed the support for SSH
1341: protocol versions 1.5 and 2.0.
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