Annotation of src/usr.bin/ssh/ssh_config.5, Revision 1.157
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
18: .\" are met:
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.
28: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35: .\"
1.157 ! naddy 36: .\" $OpenBSD: ssh_config.5,v 1.156 2012/06/28 05:07:45 dtucker Exp $
! 37: .Dd $Mdocdate: June 28 2012 $
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 ,
1.54 djm 207: .Dq arcfour128 ,
208: .Dq arcfour256 ,
1.35 dtucker 209: .Dq arcfour ,
210: .Dq blowfish-cbc ,
211: and
212: .Dq cast128-cbc .
1.84 jmc 213: The default is:
214: .Bd -literal -offset 3n
1.116 naddy 215: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
216: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
217: aes256-cbc,arcfour
1.1 stevesk 218: .Ed
219: .It Cm ClearAllForwardings
1.84 jmc 220: Specifies that all local, remote, and dynamic port forwardings
1.1 stevesk 221: specified in the configuration files or on the command line be
1.7 jmc 222: cleared.
223: This option is primarily useful when used from the
1.84 jmc 224: .Xr ssh 1
1.1 stevesk 225: command line to clear port forwardings set in
226: configuration files, and is automatically set by
227: .Xr scp 1
228: and
229: .Xr sftp 1 .
230: The argument must be
231: .Dq yes
232: or
233: .Dq no .
234: The default is
235: .Dq no .
236: .It Cm Compression
237: Specifies whether to use compression.
238: The argument must be
239: .Dq yes
240: or
241: .Dq no .
242: The default is
243: .Dq no .
244: .It Cm CompressionLevel
245: Specifies the compression level to use if compression is enabled.
246: The argument must be an integer from 1 (fast) to 9 (slow, best).
247: The default level is 6, which is good for most applications.
248: The meaning of the values is the same as in
249: .Xr gzip 1 .
250: Note that this option applies to protocol version 1 only.
251: .It Cm ConnectionAttempts
252: Specifies the number of tries (one per second) to make before exiting.
253: The argument must be an integer.
254: This may be useful in scripts if the connection sometimes fails.
255: The default is 1.
1.9 djm 256: .It Cm ConnectTimeout
1.84 jmc 257: Specifies the timeout (in seconds) used when connecting to the
258: SSH server, instead of using the default system TCP timeout.
1.11 jmc 259: This value is used only when the target is down or really unreachable,
260: not when it refuses the connection.
1.36 djm 261: .It Cm ControlMaster
262: Enables the sharing of multiple sessions over a single network connection.
263: When set to
1.84 jmc 264: .Dq yes ,
265: .Xr ssh 1
1.36 djm 266: will listen for connections on a control socket specified using the
267: .Cm ControlPath
268: argument.
269: Additional sessions can connect to this socket using the same
270: .Cm ControlPath
271: with
272: .Cm ControlMaster
273: set to
274: .Dq no
1.38 jmc 275: (the default).
1.64 jmc 276: These sessions will try to reuse the master instance's network connection
1.63 djm 277: rather than initiating new ones, but will fall back to connecting normally
278: if the control socket does not exist, or is not listening.
279: .Pp
1.37 djm 280: Setting this to
281: .Dq ask
1.84 jmc 282: will cause ssh
1.37 djm 283: to listen for control connections, but require confirmation using the
284: .Ev SSH_ASKPASS
285: program before they are accepted (see
286: .Xr ssh-add 1
1.38 jmc 287: for details).
1.51 jakob 288: If the
289: .Cm ControlPath
1.84 jmc 290: cannot be opened,
291: ssh will continue without connecting to a master instance.
1.58 djm 292: .Pp
293: X11 and
1.59 jmc 294: .Xr ssh-agent 1
1.58 djm 295: forwarding is supported over these multiplexed connections, however the
1.70 stevesk 296: display and agent forwarded will be the one belonging to the master
1.59 jmc 297: connection i.e. it is not possible to forward multiple displays or agents.
1.56 djm 298: .Pp
299: Two additional options allow for opportunistic multiplexing: try to use a
300: master connection but fall back to creating a new one if one does not already
301: exist.
302: These options are:
303: .Dq auto
304: and
305: .Dq autoask .
306: The latter requires confirmation like the
307: .Dq ask
308: option.
1.36 djm 309: .It Cm ControlPath
1.55 djm 310: Specify the path to the control socket used for connection sharing as described
311: in the
1.36 djm 312: .Cm ControlMaster
1.57 djm 313: section above or the string
314: .Dq none
315: to disable connection sharing.
1.55 djm 316: In the path,
1.147 djm 317: .Ql %L
318: will be substituted by the first component of the local host name,
1.77 djm 319: .Ql %l
1.147 djm 320: will be substituted by the local host name (including any domain name),
1.55 djm 321: .Ql %h
322: will be substituted by the target host name,
1.150 jmc 323: .Ql %n
324: will be substituted by the original target host name
325: specified on the command line,
1.55 djm 326: .Ql %p
1.147 djm 327: the port,
1.55 djm 328: .Ql %r
1.147 djm 329: by the remote login username, and
330: .Ql %u
331: by the username of the user running
332: .Xr ssh 1 .
1.56 djm 333: It is recommended that any
334: .Cm ControlPath
335: used for opportunistic connection sharing include
1.78 jmc 336: at least %h, %p, and %r.
1.56 djm 337: This ensures that shared connections are uniquely identified.
1.137 djm 338: .It Cm ControlPersist
339: When used in conjunction with
340: .Cm ControlMaster ,
341: specifies that the master connection should remain open
342: in the background (waiting for future client connections)
343: after the initial client connection has been closed.
344: If set to
345: .Dq no ,
346: then the master connection will not be placed into the background,
347: and will close as soon as the initial client connection is closed.
348: If set to
349: .Dq yes ,
350: then the master connection will remain in the background indefinitely
351: (until killed or closed via a mechanism such as the
352: .Xr ssh 1
353: .Dq Fl O No exit
354: option).
355: If set to a time in seconds, or a time in any of the formats documented in
356: .Xr sshd_config 5 ,
357: then the backgrounded master connection will automatically terminate
358: after it has remained idle (with no client connections) for the
359: specified time.
1.38 jmc 360: .It Cm DynamicForward
1.74 jmc 361: Specifies that a TCP port on the local machine be forwarded
1.38 jmc 362: over the secure channel, and the application
363: protocol is then used to determine where to connect to from the
364: remote machine.
1.62 djm 365: .Pp
366: The argument must be
367: .Sm off
368: .Oo Ar bind_address : Oc Ar port .
369: .Sm on
1.138 djm 370: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.62 djm 371: By default, the local port is bound in accordance with the
372: .Cm GatewayPorts
373: setting.
374: However, an explicit
375: .Ar bind_address
376: may be used to bind the connection to a specific address.
377: The
378: .Ar bind_address
379: of
380: .Dq localhost
381: indicates that the listening port be bound for local use only, while an
382: empty address or
383: .Sq *
384: indicates that the port should be available from all interfaces.
385: .Pp
1.38 jmc 386: Currently the SOCKS4 and SOCKS5 protocols are supported, and
1.84 jmc 387: .Xr ssh 1
1.38 jmc 388: will act as a SOCKS server.
389: Multiple forwardings may be specified, and
390: additional forwardings can be given on the command line.
391: Only the superuser can forward privileged ports.
1.14 markus 392: .It Cm EnableSSHKeysign
393: Setting this option to
394: .Dq yes
395: in the global client configuration file
396: .Pa /etc/ssh/ssh_config
397: enables the use of the helper program
398: .Xr ssh-keysign 8
399: during
400: .Cm HostbasedAuthentication .
401: The argument must be
402: .Dq yes
403: or
404: .Dq no .
405: The default is
406: .Dq no .
1.23 jmc 407: This option should be placed in the non-hostspecific section.
1.14 markus 408: See
409: .Xr ssh-keysign 8
410: for more information.
1.1 stevesk 411: .It Cm EscapeChar
412: Sets the escape character (default:
413: .Ql ~ ) .
414: The escape character can also
415: be set on the command line.
416: The argument should be a single character,
417: .Ql ^
418: followed by a letter, or
419: .Dq none
420: to disable the escape
421: character entirely (making the connection transparent for binary
422: data).
1.96 markus 423: .It Cm ExitOnForwardFailure
424: Specifies whether
425: .Xr ssh 1
426: should terminate the connection if it cannot set up all requested
1.102 stevesk 427: dynamic, tunnel, local, and remote port forwardings.
1.96 markus 428: The argument must be
429: .Dq yes
430: or
431: .Dq no .
432: The default is
433: .Dq no .
1.1 stevesk 434: .It Cm ForwardAgent
435: Specifies whether the connection to the authentication agent (if any)
436: will be forwarded to the remote machine.
437: The argument must be
438: .Dq yes
439: or
440: .Dq no .
441: The default is
442: .Dq no .
1.3 stevesk 443: .Pp
1.7 jmc 444: Agent forwarding should be enabled with caution.
445: Users with the ability to bypass file permissions on the remote host
446: (for the agent's Unix-domain socket)
447: can access the local agent through the forwarded connection.
448: An attacker cannot obtain key material from the agent,
1.3 stevesk 449: however they can perform operations on the keys that enable them to
450: authenticate using the identities loaded into the agent.
1.1 stevesk 451: .It Cm ForwardX11
452: Specifies whether X11 connections will be automatically redirected
453: over the secure channel and
454: .Ev DISPLAY
455: set.
456: The argument must be
457: .Dq yes
458: or
459: .Dq no .
460: The default is
461: .Dq no .
1.3 stevesk 462: .Pp
1.7 jmc 463: X11 forwarding should be enabled with caution.
464: Users with the ability to bypass file permissions on the remote host
1.22 markus 465: (for the user's X11 authorization database)
1.7 jmc 466: can access the local X11 display through the forwarded connection.
1.22 markus 467: An attacker may then be able to perform activities such as keystroke monitoring
468: if the
469: .Cm ForwardX11Trusted
470: option is also enabled.
1.134 djm 471: .It Cm ForwardX11Timeout
1.135 jmc 472: Specify a timeout for untrusted X11 forwarding
473: using the format described in the
1.134 djm 474: .Sx TIME FORMATS
475: section of
476: .Xr sshd_config 5 .
477: X11 connections received by
478: .Xr ssh 1
479: after this time will be refused.
480: The default is to disable untrusted X11 forwarding after twenty minutes has
481: elapsed.
1.22 markus 482: .It Cm ForwardX11Trusted
1.34 jmc 483: If this option is set to
1.84 jmc 484: .Dq yes ,
485: remote X11 clients will have full access to the original X11 display.
1.42 djm 486: .Pp
1.22 markus 487: If this option is set to
1.84 jmc 488: .Dq no ,
489: remote X11 clients will be considered untrusted and prevented
1.22 markus 490: from stealing or tampering with data belonging to trusted X11
491: clients.
1.42 djm 492: Furthermore, the
493: .Xr xauth 1
494: token used for the session will be set to expire after 20 minutes.
495: Remote clients will be refused access after this time.
1.22 markus 496: .Pp
497: The default is
498: .Dq no .
499: .Pp
500: See the X11 SECURITY extension specification for full details on
501: the restrictions imposed on untrusted clients.
1.1 stevesk 502: .It Cm GatewayPorts
503: Specifies whether remote hosts are allowed to connect to local
504: forwarded ports.
505: By default,
1.84 jmc 506: .Xr ssh 1
1.7 jmc 507: binds local port forwardings to the loopback address.
508: This prevents other remote hosts from connecting to forwarded ports.
1.1 stevesk 509: .Cm GatewayPorts
1.84 jmc 510: can be used to specify that ssh
1.1 stevesk 511: should bind local port forwardings to the wildcard address,
512: thus allowing remote hosts to connect to forwarded ports.
513: The argument must be
514: .Dq yes
515: or
516: .Dq no .
517: The default is
518: .Dq no .
519: .It Cm GlobalKnownHostsFile
1.151 djm 520: Specifies one or more files to use for the global
521: host key database, separated by whitespace.
522: The default is
523: .Pa /etc/ssh/ssh_known_hosts ,
524: .Pa /etc/ssh/ssh_known_hosts2 .
1.18 markus 525: .It Cm GSSAPIAuthentication
1.27 markus 526: Specifies whether user authentication based on GSSAPI is allowed.
1.20 jmc 527: The default is
1.21 markus 528: .Dq no .
1.18 markus 529: Note that this option applies to protocol version 2 only.
530: .It Cm GSSAPIDelegateCredentials
531: Forward (delegate) credentials to the server.
532: The default is
533: .Dq no .
534: Note that this option applies to protocol version 2 only.
1.44 djm 535: .It Cm HashKnownHosts
536: Indicates that
1.84 jmc 537: .Xr ssh 1
1.44 djm 538: should hash host names and addresses when they are added to
1.50 djm 539: .Pa ~/.ssh/known_hosts .
1.44 djm 540: These hashed names may be used normally by
1.84 jmc 541: .Xr ssh 1
1.44 djm 542: and
1.84 jmc 543: .Xr sshd 8 ,
1.44 djm 544: but they do not reveal identifying information should the file's contents
545: be disclosed.
546: The default is
547: .Dq no .
1.97 jmc 548: Note that existing names and addresses in known hosts files
549: will not be converted automatically,
550: but may be manually hashed using
1.45 djm 551: .Xr ssh-keygen 1 .
1.1 stevesk 552: .It Cm HostbasedAuthentication
553: Specifies whether to try rhosts based authentication with public key
554: authentication.
555: The argument must be
556: .Dq yes
557: or
558: .Dq no .
559: The default is
560: .Dq no .
561: This option applies to protocol version 2 only and
562: is similar to
563: .Cm RhostsRSAAuthentication .
564: .It Cm HostKeyAlgorithms
565: Specifies the protocol version 2 host key algorithms
566: that the client wants to use in order of preference.
567: The default for this option is:
1.139 djm 568: .Bd -literal -offset 3n
569: ecdsa-sha2-nistp256-cert-v01@openssh.com,
570: ecdsa-sha2-nistp384-cert-v01@openssh.com,
571: ecdsa-sha2-nistp521-cert-v01@openssh.com,
572: ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,
573: ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,
574: ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
575: ssh-rsa,ssh-dss
576: .Ed
1.145 djm 577: .Pp
578: If hostkeys are known for the destination host then this default is modified
579: to prefer their algorithms.
1.1 stevesk 580: .It Cm HostKeyAlias
581: Specifies an alias that should be used instead of the
582: real host name when looking up or saving the host key
583: in the host key database files.
1.84 jmc 584: This option is useful for tunneling SSH connections
1.1 stevesk 585: or for multiple servers running on a single host.
586: .It Cm HostName
587: Specifies the real host name to log into.
588: This can be used to specify nicknames or abbreviations for hosts.
1.136 djm 589: If the hostname contains the character sequence
590: .Ql %h ,
1.150 jmc 591: then this will be replaced with the host name specified on the command line
1.136 djm 592: (this is useful for manipulating unqualified names).
1.84 jmc 593: The default is the name given on the command line.
1.1 stevesk 594: Numeric IP addresses are also permitted (both on the command line and in
595: .Cm HostName
596: specifications).
1.29 markus 597: .It Cm IdentitiesOnly
598: Specifies that
1.84 jmc 599: .Xr ssh 1
1.29 markus 600: should only use the authentication identity files configured in the
1.31 jmc 601: .Nm
1.29 markus 602: files,
1.84 jmc 603: even if
604: .Xr ssh-agent 1
1.29 markus 605: offers more identities.
606: The argument to this keyword must be
607: .Dq yes
608: or
609: .Dq no .
1.84 jmc 610: This option is intended for situations where ssh-agent
1.29 markus 611: offers many different identities.
612: The default is
613: .Dq no .
1.67 jmc 614: .It Cm IdentityFile
1.155 dtucker 615: Specifies a file from which the user's DSA, ECDSA or RSA authentication
1.139 djm 616: identity is read.
1.67 jmc 617: The default is
618: .Pa ~/.ssh/identity
619: for protocol version 1, and
1.139 djm 620: .Pa ~/.ssh/id_dsa ,
621: .Pa ~/.ssh/id_ecdsa
622: and
1.67 jmc 623: .Pa ~/.ssh/id_rsa
624: for protocol version 2.
625: Additionally, any identities represented by the authentication agent
626: will be used for authentication.
1.129 djm 627: .Xr ssh 1
628: will try to load certificate information from the filename obtained by
629: appending
630: .Pa -cert.pub
631: to the path of a specified
632: .Cm IdentityFile .
1.90 djm 633: .Pp
1.67 jmc 634: The file name may use the tilde
1.91 jmc 635: syntax to refer to a user's home directory or one of the following
1.90 djm 636: escape characters:
637: .Ql %d
638: (local user's home directory),
639: .Ql %u
640: (local user name),
641: .Ql %l
642: (local host name),
643: .Ql %h
644: (remote host name) or
1.92 djm 645: .Ql %r
1.90 djm 646: (remote user name).
647: .Pp
1.67 jmc 648: It is possible to have
649: multiple identity files specified in configuration files; all these
650: identities will be tried in sequence.
1.152 djm 651: Multiple
652: .Cm IdentityFile
653: directives will add to the list of identities tried (this behaviour
654: differs from that of other configuration directives).
1.143 djm 655: .It Cm IPQoS
656: Specifies the IPv4 type-of-service or DSCP class for connections.
657: Accepted values are
658: .Dq af11 ,
659: .Dq af12 ,
660: .Dq af13 ,
1.154 djm 661: .Dq af21 ,
1.143 djm 662: .Dq af22 ,
663: .Dq af23 ,
664: .Dq af31 ,
665: .Dq af32 ,
666: .Dq af33 ,
667: .Dq af41 ,
668: .Dq af42 ,
669: .Dq af43 ,
670: .Dq cs0 ,
671: .Dq cs1 ,
672: .Dq cs2 ,
673: .Dq cs3 ,
674: .Dq cs4 ,
675: .Dq cs5 ,
676: .Dq cs6 ,
677: .Dq cs7 ,
678: .Dq ef ,
679: .Dq lowdelay ,
680: .Dq throughput ,
681: .Dq reliability ,
682: or a numeric value.
1.146 djm 683: This option may take one or two arguments, separated by whitespace.
1.143 djm 684: If one argument is specified, it is used as the packet class unconditionally.
685: If two values are specified, the first is automatically selected for
686: interactive sessions and the second for non-interactive sessions.
687: The default is
688: .Dq lowdelay
689: for interactive sessions and
690: .Dq throughput
691: for non-interactive sessions.
1.103 djm 692: .It Cm KbdInteractiveAuthentication
693: Specifies whether to use keyboard-interactive authentication.
694: The argument to this keyword must be
695: .Dq yes
696: or
697: .Dq no .
698: The default is
699: .Dq yes .
1.39 djm 700: .It Cm KbdInteractiveDevices
701: Specifies the list of methods to use in keyboard-interactive authentication.
702: Multiple method names must be comma-separated.
703: The default is to use the server specified list.
1.85 jmc 704: The methods available vary depending on what the server supports.
705: For an OpenSSH server,
706: it may be zero or more of:
707: .Dq bsdauth ,
708: .Dq pam ,
709: and
710: .Dq skey .
1.140 djm 711: .It Cm KexAlgorithms
712: Specifies the available KEX (Key Exchange) algorithms.
713: Multiple algorithms must be comma-separated.
1.141 jmc 714: The default is:
715: .Bd -literal -offset indent
716: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
717: diffie-hellman-group-exchange-sha256,
718: diffie-hellman-group-exchange-sha1,
719: diffie-hellman-group14-sha1,
720: diffie-hellman-group1-sha1
721: .Ed
1.65 reyk 722: .It Cm LocalCommand
723: Specifies a command to execute on the local machine after successfully
724: connecting to the server.
725: The command string extends to the end of the line, and is executed with
1.105 jmc 726: the user's shell.
1.109 dtucker 727: The following escape character substitutions will be performed:
728: .Ql %d
729: (local user's home directory),
730: .Ql %h
731: (remote host name),
732: .Ql %l
733: (local host name),
734: .Ql %n
735: (host name as provided on the command line),
736: .Ql %p
737: (remote port),
738: .Ql %r
739: (remote user name) or
740: .Ql %u
741: (local user name).
1.123 djm 742: .Pp
743: The command is run synchronously and does not have access to the
744: session of the
745: .Xr ssh 1
746: that spawned it.
747: It should not be used for interactive commands.
748: .Pp
1.65 reyk 749: This directive is ignored unless
750: .Cm PermitLocalCommand
751: has been enabled.
1.1 stevesk 752: .It Cm LocalForward
1.74 jmc 753: Specifies that a TCP port on the local machine be forwarded over
1.1 stevesk 754: the secure channel to the specified host and port from the remote machine.
1.49 jmc 755: The first argument must be
1.43 djm 756: .Sm off
1.49 jmc 757: .Oo Ar bind_address : Oc Ar port
1.43 djm 758: .Sm on
1.49 jmc 759: and the second argument must be
760: .Ar host : Ns Ar hostport .
1.138 djm 761: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.46 jmc 762: Multiple forwardings may be specified, and additional forwardings can be
1.43 djm 763: given on the command line.
1.1 stevesk 764: Only the superuser can forward privileged ports.
1.43 djm 765: By default, the local port is bound in accordance with the
766: .Cm GatewayPorts
767: setting.
768: However, an explicit
769: .Ar bind_address
770: may be used to bind the connection to a specific address.
771: The
772: .Ar bind_address
773: of
774: .Dq localhost
1.46 jmc 775: indicates that the listening port be bound for local use only, while an
776: empty address or
777: .Sq *
1.43 djm 778: indicates that the port should be available from all interfaces.
1.1 stevesk 779: .It Cm LogLevel
780: Gives the verbosity level that is used when logging messages from
1.84 jmc 781: .Xr ssh 1 .
1.1 stevesk 782: The possible values are:
1.84 jmc 783: QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.
1.7 jmc 784: The default is INFO.
785: DEBUG and DEBUG1 are equivalent.
786: DEBUG2 and DEBUG3 each specify higher levels of verbose output.
1.1 stevesk 787: .It Cm MACs
788: Specifies the MAC (message authentication code) algorithms
789: in order of preference.
790: The MAC algorithm is used in protocol version 2
791: for data integrity protection.
792: Multiple algorithms must be comma-separated.
1.84 jmc 793: The default is:
1.101 jmc 794: .Bd -literal -offset indent
795: hmac-md5,hmac-sha1,umac-64@openssh.com,
1.157 ! naddy 796: hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,
! 797: hmac-sha1-96,hmac-md5-96
1.101 jmc 798: .Ed
1.1 stevesk 799: .It Cm NoHostAuthenticationForLocalhost
800: This option can be used if the home directory is shared across machines.
801: In this case localhost will refer to a different machine on each of
802: the machines and the user will get many warnings about changed host keys.
803: However, this option disables host authentication for localhost.
804: The argument to this keyword must be
805: .Dq yes
806: or
807: .Dq no .
808: The default is to check the host key for localhost.
809: .It Cm NumberOfPasswordPrompts
810: Specifies the number of password prompts before giving up.
811: The argument to this keyword must be an integer.
1.84 jmc 812: The default is 3.
1.1 stevesk 813: .It Cm PasswordAuthentication
814: Specifies whether to use password authentication.
815: The argument to this keyword must be
816: .Dq yes
817: or
818: .Dq no .
819: The default is
820: .Dq yes .
1.65 reyk 821: .It Cm PermitLocalCommand
822: Allow local command execution via the
823: .Ic LocalCommand
824: option or using the
1.66 jmc 825: .Ic !\& Ns Ar command
1.65 reyk 826: escape sequence in
827: .Xr ssh 1 .
828: The argument must be
829: .Dq yes
830: or
831: .Dq no .
832: The default is
833: .Dq no .
1.127 markus 834: .It Cm PKCS11Provider
835: Specifies which PKCS#11 provider to use.
1.144 jmc 836: The argument to this keyword is the PKCS#11 shared library
1.127 markus 837: .Xr ssh 1
1.128 markus 838: should use to communicate with a PKCS#11 token providing the user's
1.127 markus 839: private RSA key.
1.67 jmc 840: .It Cm Port
841: Specifies the port number to connect on the remote host.
1.84 jmc 842: The default is 22.
1.1 stevesk 843: .It Cm PreferredAuthentications
844: Specifies the order in which the client should try protocol 2
1.11 jmc 845: authentication methods.
1.48 jmc 846: This allows a client to prefer one method (e.g.\&
1.1 stevesk 847: .Cm keyboard-interactive )
1.48 jmc 848: over another method (e.g.\&
1.131 jmc 849: .Cm password ) .
850: The default is:
851: .Bd -literal -offset indent
852: gssapi-with-mic,hostbased,publickey,
853: keyboard-interactive,password
854: .Ed
1.1 stevesk 855: .It Cm Protocol
856: Specifies the protocol versions
1.84 jmc 857: .Xr ssh 1
1.1 stevesk 858: should support in order of preference.
859: The possible values are
1.84 jmc 860: .Sq 1
1.1 stevesk 861: and
1.84 jmc 862: .Sq 2 .
1.1 stevesk 863: Multiple versions must be comma-separated.
1.120 markus 864: When this option is set to
1.121 jmc 865: .Dq 2,1
1.120 markus 866: .Nm ssh
867: will try version 2 and fall back to version 1
868: if version 2 is not available.
1.1 stevesk 869: The default is
1.121 jmc 870: .Sq 2 .
1.1 stevesk 871: .It Cm ProxyCommand
872: Specifies the command to use to connect to the server.
873: The command
874: string extends to the end of the line, and is executed with
1.105 jmc 875: the user's shell.
1.133 jmc 876: In the command string, any occurrence of
1.1 stevesk 877: .Ql %h
878: will be substituted by the host name to
1.132 djm 879: connect,
1.1 stevesk 880: .Ql %p
1.133 jmc 881: by the port, and
882: .Ql %r
1.132 djm 883: by the remote user name.
1.1 stevesk 884: The command can be basically anything,
885: and should read from its standard input and write to its standard output.
886: It should eventually connect an
887: .Xr sshd 8
888: server running on some machine, or execute
889: .Ic sshd -i
890: somewhere.
891: Host key management will be done using the
892: HostName of the host being connected (defaulting to the name typed by
893: the user).
1.7 jmc 894: Setting the command to
895: .Dq none
1.6 markus 896: disables this option entirely.
1.1 stevesk 897: Note that
898: .Cm CheckHostIP
899: is not available for connects with a proxy command.
1.52 djm 900: .Pp
901: This directive is useful in conjunction with
902: .Xr nc 1
903: and its proxy support.
1.53 jmc 904: For example, the following directive would connect via an HTTP proxy at
1.52 djm 905: 192.0.2.0:
906: .Bd -literal -offset 3n
907: ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p
908: .Ed
1.1 stevesk 909: .It Cm PubkeyAuthentication
910: Specifies whether to try public key authentication.
911: The argument to this keyword must be
912: .Dq yes
913: or
914: .Dq no .
915: The default is
916: .Dq yes .
917: This option applies to protocol version 2 only.
1.75 dtucker 918: .It Cm RekeyLimit
919: Specifies the maximum amount of data that may be transmitted before the
1.76 jmc 920: session key is renegotiated.
1.75 dtucker 921: The argument is the number of bytes, with an optional suffix of
1.76 jmc 922: .Sq K ,
923: .Sq M ,
1.75 dtucker 924: or
1.76 jmc 925: .Sq G
1.75 dtucker 926: to indicate Kilobytes, Megabytes, or Gigabytes, respectively.
927: The default is between
1.84 jmc 928: .Sq 1G
1.75 dtucker 929: and
1.84 jmc 930: .Sq 4G ,
1.75 dtucker 931: depending on the cipher.
1.76 jmc 932: This option applies to protocol version 2 only.
1.1 stevesk 933: .It Cm RemoteForward
1.74 jmc 934: Specifies that a TCP port on the remote machine be forwarded over
1.1 stevesk 935: the secure channel to the specified host and port from the local machine.
1.49 jmc 936: The first argument must be
1.43 djm 937: .Sm off
1.49 jmc 938: .Oo Ar bind_address : Oc Ar port
1.43 djm 939: .Sm on
1.49 jmc 940: and the second argument must be
941: .Ar host : Ns Ar hostport .
1.138 djm 942: IPv6 addresses can be specified by enclosing addresses in square brackets.
1.1 stevesk 943: Multiple forwardings may be specified, and additional
944: forwardings can be given on the command line.
1.113 stevesk 945: Privileged ports can be forwarded only when
946: logging in as root on the remote machine.
1.118 jmc 947: .Pp
1.117 djm 948: If the
949: .Ar port
950: argument is
951: .Ql 0 ,
952: the listen port will be dynamically allocated on the server and reported
953: to the client at run time.
1.43 djm 954: .Pp
955: If the
956: .Ar bind_address
957: is not specified, the default is to only bind to loopback addresses.
958: If the
959: .Ar bind_address
960: is
961: .Ql *
962: or an empty string, then the forwarding is requested to listen on all
963: interfaces.
964: Specifying a remote
965: .Ar bind_address
1.46 jmc 966: will only succeed if the server's
967: .Cm GatewayPorts
1.43 djm 968: option is enabled (see
1.46 jmc 969: .Xr sshd_config 5 ) .
1.149 djm 970: .It Cm RequestTTY
971: Specifies whether to request a pseudo-tty for the session.
972: The argument may be one of:
973: .Dq no
974: (never request a TTY),
975: .Dq yes
976: (always request a TTY when standard input is a TTY),
977: .Dq force
978: (always request a TTY) or
979: .Dq auto
980: (request a TTY when opening a login session).
981: This option mirrors the
982: .Fl t
983: and
984: .Fl T
985: flags for
986: .Xr ssh 1 .
1.1 stevesk 987: .It Cm RhostsRSAAuthentication
988: Specifies whether to try rhosts based authentication with RSA host
989: authentication.
990: The argument must be
991: .Dq yes
992: or
993: .Dq no .
994: The default is
995: .Dq no .
996: This option applies to protocol version 1 only and requires
1.84 jmc 997: .Xr ssh 1
1.1 stevesk 998: to be setuid root.
999: .It Cm RSAAuthentication
1000: Specifies whether to try RSA authentication.
1001: The argument to this keyword must be
1002: .Dq yes
1003: or
1004: .Dq no .
1005: RSA authentication will only be
1006: attempted if the identity file exists, or an authentication agent is
1007: running.
1008: The default is
1009: .Dq yes .
1010: Note that this option applies to protocol version 1 only.
1.32 djm 1011: .It Cm SendEnv
1012: Specifies what variables from the local
1013: .Xr environ 7
1014: should be sent to the server.
1.84 jmc 1015: Note that environment passing is only supported for protocol 2.
1016: The server must also support it, and the server must be configured to
1.33 djm 1017: accept these environment variables.
1.32 djm 1018: Refer to
1019: .Cm AcceptEnv
1020: in
1021: .Xr sshd_config 5
1022: for how to configure the server.
1.80 jmc 1023: Variables are specified by name, which may contain wildcard characters.
1.33 djm 1024: Multiple environment variables may be separated by whitespace or spread
1.32 djm 1025: across multiple
1026: .Cm SendEnv
1027: directives.
1028: The default is not to send any environment variables.
1.81 jmc 1029: .Pp
1030: See
1031: .Sx PATTERNS
1032: for more information on patterns.
1.28 markus 1033: .It Cm ServerAliveCountMax
1.73 jmc 1034: Sets the number of server alive messages (see below) which may be
1.28 markus 1035: sent without
1.84 jmc 1036: .Xr ssh 1
1.28 markus 1037: receiving any messages back from the server.
1038: If this threshold is reached while server alive messages are being sent,
1.84 jmc 1039: ssh will disconnect from the server, terminating the session.
1.28 markus 1040: It is important to note that the use of server alive messages is very
1041: different from
1042: .Cm TCPKeepAlive
1043: (below).
1044: The server alive messages are sent through the encrypted channel
1045: and therefore will not be spoofable.
1046: The TCP keepalive option enabled by
1047: .Cm TCPKeepAlive
1048: is spoofable.
1049: The server alive mechanism is valuable when the client or
1050: server depend on knowing when a connection has become inactive.
1051: .Pp
1052: The default value is 3.
1053: If, for example,
1054: .Cm ServerAliveInterval
1.84 jmc 1055: (see below) is set to 15 and
1.28 markus 1056: .Cm ServerAliveCountMax
1.84 jmc 1057: is left at the default, if the server becomes unresponsive,
1058: ssh will disconnect after approximately 45 seconds.
1.89 markus 1059: This option applies to protocol version 2 only.
1.67 jmc 1060: .It Cm ServerAliveInterval
1061: Sets a timeout interval in seconds after which if no data has been received
1062: from the server,
1.84 jmc 1063: .Xr ssh 1
1.67 jmc 1064: will send a message through the encrypted
1065: channel to request a response from the server.
1066: The default
1067: is 0, indicating that these messages will not be sent to the server.
1068: This option applies to protocol version 2 only.
1.1 stevesk 1069: .It Cm StrictHostKeyChecking
1070: If this flag is set to
1071: .Dq yes ,
1.84 jmc 1072: .Xr ssh 1
1.1 stevesk 1073: will never automatically add host keys to the
1.50 djm 1074: .Pa ~/.ssh/known_hosts
1.1 stevesk 1075: file, and refuses to connect to hosts whose host key has changed.
1076: This provides maximum protection against trojan horse attacks,
1.84 jmc 1077: though it can be annoying when the
1.1 stevesk 1078: .Pa /etc/ssh/ssh_known_hosts
1.84 jmc 1079: file is poorly maintained or when connections to new hosts are
1.1 stevesk 1080: frequently made.
1081: This option forces the user to manually
1082: add all new hosts.
1083: If this flag is set to
1084: .Dq no ,
1.84 jmc 1085: ssh will automatically add new host keys to the
1.1 stevesk 1086: user known hosts files.
1087: If this flag is set to
1088: .Dq ask ,
1089: new host keys
1090: will be added to the user known host files only after the user
1091: has confirmed that is what they really want to do, and
1.84 jmc 1092: ssh will refuse to connect to hosts whose host key has changed.
1.1 stevesk 1093: The host keys of
1094: known hosts will be verified automatically in all cases.
1095: The argument must be
1096: .Dq yes ,
1.84 jmc 1097: .Dq no ,
1.1 stevesk 1098: or
1099: .Dq ask .
1100: The default is
1101: .Dq ask .
1.26 markus 1102: .It Cm TCPKeepAlive
1103: Specifies whether the system should send TCP keepalive messages to the
1104: other side.
1105: If they are sent, death of the connection or crash of one
1106: of the machines will be properly noticed.
1107: However, this means that
1108: connections will die if the route is down temporarily, and some people
1109: find it annoying.
1110: .Pp
1111: The default is
1112: .Dq yes
1113: (to send TCP keepalive messages), and the client will notice
1114: if the network goes down or the remote host dies.
1115: This is important in scripts, and many users want it too.
1116: .Pp
1117: To disable TCP keepalive messages, the value should be set to
1118: .Dq no .
1.65 reyk 1119: .It Cm Tunnel
1.95 stevesk 1120: Request
1.65 reyk 1121: .Xr tun 4
1.69 jmc 1122: device forwarding between the client and the server.
1.65 reyk 1123: The argument must be
1.68 reyk 1124: .Dq yes ,
1.95 stevesk 1125: .Dq point-to-point
1126: (layer 3),
1127: .Dq ethernet
1128: (layer 2),
1.65 reyk 1129: or
1130: .Dq no .
1.95 stevesk 1131: Specifying
1132: .Dq yes
1133: requests the default tunnel mode, which is
1134: .Dq point-to-point .
1.65 reyk 1135: The default is
1136: .Dq no .
1137: .It Cm TunnelDevice
1.95 stevesk 1138: Specifies the
1.65 reyk 1139: .Xr tun 4
1.95 stevesk 1140: devices to open on the client
1141: .Pq Ar local_tun
1142: and the server
1143: .Pq Ar remote_tun .
1144: .Pp
1145: The argument must be
1146: .Sm off
1147: .Ar local_tun Op : Ar remote_tun .
1148: .Sm on
1149: The devices may be specified by numerical ID or the keyword
1150: .Dq any ,
1151: which uses the next available tunnel device.
1152: If
1153: .Ar remote_tun
1154: is not specified, it defaults to
1155: .Dq any .
1156: The default is
1157: .Dq any:any .
1.72 jmc 1158: .It Cm UsePrivilegedPort
1159: Specifies whether to use a privileged port for outgoing connections.
1160: The argument must be
1161: .Dq yes
1162: or
1163: .Dq no .
1164: The default is
1165: .Dq no .
1166: If set to
1.84 jmc 1167: .Dq yes ,
1168: .Xr ssh 1
1.72 jmc 1169: must be setuid root.
1170: Note that this option must be set to
1171: .Dq yes
1172: for
1173: .Cm RhostsRSAAuthentication
1174: with older servers.
1.1 stevesk 1175: .It Cm User
1176: Specifies the user to log in as.
1177: This can be useful when a different user name is used on different machines.
1178: This saves the trouble of
1179: having to remember to give the user name on the command line.
1180: .It Cm UserKnownHostsFile
1.151 djm 1181: Specifies one or more files to use for the user
1182: host key database, separated by whitespace.
1183: The default is
1184: .Pa ~/.ssh/known_hosts ,
1185: .Pa ~/.ssh/known_hosts2 .
1.8 jakob 1186: .It Cm VerifyHostKeyDNS
1187: Specifies whether to verify the remote key using DNS and SSHFP resource
1188: records.
1.24 jakob 1189: If this option is set to
1190: .Dq yes ,
1.25 jmc 1191: the client will implicitly trust keys that match a secure fingerprint
1.24 jakob 1192: from DNS.
1193: Insecure fingerprints will be handled as if this option was set to
1194: .Dq ask .
1195: If this option is set to
1196: .Dq ask ,
1197: information on fingerprint match will be displayed, but the user will still
1198: need to confirm new host keys according to the
1199: .Cm StrictHostKeyChecking
1200: option.
1201: The argument must be
1202: .Dq yes ,
1.84 jmc 1203: .Dq no ,
1.25 jmc 1204: or
1205: .Dq ask .
1.8 jakob 1206: The default is
1207: .Dq no .
1.12 jakob 1208: Note that this option applies to protocol version 2 only.
1.84 jmc 1209: .Pp
1210: See also
1211: .Sx VERIFYING HOST KEYS
1212: in
1213: .Xr ssh 1 .
1.111 grunk 1214: .It Cm VisualHostKey
1215: If this flag is set to
1216: .Dq yes ,
1217: an ASCII art representation of the remote host key fingerprint is
1.114 stevesk 1218: printed in addition to the hex fingerprint string at login and
1219: for unknown host keys.
1.111 grunk 1220: If this flag is set to
1221: .Dq no ,
1.114 stevesk 1222: no fingerprint strings are printed at login and
1223: only the hex fingerprint string will be printed for unknown host keys.
1.111 grunk 1224: The default is
1225: .Dq no .
1.1 stevesk 1226: .It Cm XAuthLocation
1.5 stevesk 1227: Specifies the full pathname of the
1.1 stevesk 1228: .Xr xauth 1
1229: program.
1230: The default is
1231: .Pa /usr/X11R6/bin/xauth .
1232: .El
1.86 jmc 1233: .Sh PATTERNS
1234: A
1235: .Em pattern
1236: consists of zero or more non-whitespace characters,
1237: .Sq *
1238: (a wildcard that matches zero or more characters),
1239: or
1240: .Sq ?\&
1241: (a wildcard that matches exactly one character).
1242: For example, to specify a set of declarations for any host in the
1243: .Dq .co.uk
1244: set of domains,
1245: the following pattern could be used:
1246: .Pp
1247: .Dl Host *.co.uk
1248: .Pp
1249: The following pattern
1250: would match any host in the 192.168.0.[0-9] network range:
1251: .Pp
1252: .Dl Host 192.168.0.?
1253: .Pp
1254: A
1255: .Em pattern-list
1256: is a comma-separated list of patterns.
1257: Patterns within pattern-lists may be negated
1258: by preceding them with an exclamation mark
1259: .Pq Sq !\& .
1260: For example,
1261: to allow a key to be used from anywhere within an organisation
1262: except from the
1263: .Dq dialup
1264: pool,
1265: the following entry (in authorized_keys) could be used:
1266: .Pp
1267: .Dl from=\&"!*.dialup.example.com,*.example.com\&"
1.1 stevesk 1268: .Sh FILES
1269: .Bl -tag -width Ds
1.50 djm 1270: .It Pa ~/.ssh/config
1.1 stevesk 1271: This is the per-user configuration file.
1272: The format of this file is described above.
1.84 jmc 1273: This file is used by the SSH client.
1.30 djm 1274: Because of the potential for abuse, this file must have strict permissions:
1275: read/write for the user, and not accessible by others.
1.1 stevesk 1276: .It Pa /etc/ssh/ssh_config
1277: Systemwide configuration file.
1278: This file provides defaults for those
1279: values that are not specified in the user's configuration file, and
1280: for those users who do not have a configuration file.
1281: This file must be world-readable.
1282: .El
1.13 jmc 1283: .Sh SEE ALSO
1284: .Xr ssh 1
1.1 stevesk 1285: .Sh AUTHORS
1286: OpenSSH is a derivative of the original and free
1287: ssh 1.2.12 release by Tatu Ylonen.
1288: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1289: Theo de Raadt and Dug Song
1290: removed many bugs, re-added newer features and
1291: created OpenSSH.
1292: Markus Friedl contributed the support for SSH
1293: protocol versions 1.5 and 2.0.
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh_config.5 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh