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f5799ae1 | 1 | .\" -*- nroff -*- |
2 | .\" | |
3 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | .\" All rights reserved | |
6 | .\" | |
7 | .\" As far as I am concerned, the code I have written for this software | |
8 | .\" can be used freely for any purpose. Any derived versions of this | |
9 | .\" software must be clearly marked as such, and if the derived work is | |
10 | .\" incompatible with the protocol description in the RFC file, it must be | |
11 | .\" called by a name other than "ssh" or "Secure Shell". | |
12 | .\" | |
13 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. | |
14 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. | |
15 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. | |
16 | .\" | |
17 | .\" Redistribution and use in source and binary forms, with or without | |
18 | .\" modification, are permitted provided that the following conditions | |
19 | .\" are met: | |
20 | .\" 1. Redistributions of source code must retain the above copyright | |
21 | .\" notice, this list of conditions and the following disclaimer. | |
22 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
23 | .\" notice, this list of conditions and the following disclaimer in the | |
24 | .\" documentation and/or other materials provided with the distribution. | |
25 | .\" | |
26 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
27 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
28 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
29 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
30 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
31 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
32 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
33 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
34 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
35 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
36 | .\" | |
91d9cdd3 | 37 | .\" $OpenBSD: ssh_config.5,v 1.119 2009/02/22 23:50:57 djm Exp $ |
38 | .Dd $Mdocdate: February 22 2009 $ | |
f5799ae1 | 39 | .Dt SSH_CONFIG 5 |
40 | .Os | |
41 | .Sh NAME | |
42 | .Nm ssh_config | |
43 | .Nd OpenSSH SSH client configuration files | |
44 | .Sh SYNOPSIS | |
799ae497 | 45 | .Nm ~/.ssh/config |
46 | .Nm /etc/ssh/ssh_config | |
f5799ae1 | 47 | .Sh DESCRIPTION |
9108f8d9 | 48 | .Xr ssh 1 |
f5799ae1 | 49 | obtains configuration data from the following sources in |
50 | the following order: | |
9108f8d9 | 51 | .Pp |
41b2f314 | 52 | .Bl -enum -offset indent -compact |
53 | .It | |
54 | command-line options | |
55 | .It | |
56 | user's configuration file | |
665a873d | 57 | .Pq Pa ~/.ssh/config |
41b2f314 | 58 | .It |
59 | system-wide configuration file | |
60 | .Pq Pa /etc/ssh/ssh_config | |
61 | .El | |
f5799ae1 | 62 | .Pp |
63 | For each parameter, the first obtained value | |
64 | will be used. | |
996d5e62 | 65 | The configuration files contain sections separated by |
f5799ae1 | 66 | .Dq Host |
67 | specifications, and that section is only applied for hosts that | |
68 | match one of the patterns given in the specification. | |
69 | The matched host name is the one given on the command line. | |
70 | .Pp | |
71 | Since the first obtained value for each parameter is used, more | |
72 | host-specific declarations should be given near the beginning of the | |
73 | file, and general defaults at the end. | |
74 | .Pp | |
75 | The configuration file has the following format: | |
76 | .Pp | |
77 | Empty lines and lines starting with | |
78 | .Ql # | |
79 | are comments. | |
f5799ae1 | 80 | Otherwise a line is of the format |
81 | .Dq keyword arguments . | |
82 | Configuration options may be separated by whitespace or | |
83 | optional whitespace and exactly one | |
84 | .Ql = ; | |
85 | the latter format is useful to avoid the need to quote whitespace | |
86 | when specifying configuration options using the | |
87 | .Nm ssh , | |
9108f8d9 | 88 | .Nm scp , |
f5799ae1 | 89 | and |
90 | .Nm sftp | |
91 | .Fl o | |
92 | option. | |
9108f8d9 | 93 | Arguments may optionally be enclosed in double quotes |
94 | .Pq \&" | |
95 | in order to represent arguments containing spaces. | |
f5799ae1 | 96 | .Pp |
97 | The possible | |
98 | keywords and their meanings are as follows (note that | |
99 | keywords are case-insensitive and arguments are case-sensitive): | |
100 | .Bl -tag -width Ds | |
101 | .It Cm Host | |
102 | Restricts the following declarations (up to the next | |
103 | .Cm Host | |
104 | keyword) to be only for those hosts that match one of the patterns | |
105 | given after the keyword. | |
91d9cdd3 | 106 | If more than one pattern is provided, they should be separated by whitespace. |
f5799ae1 | 107 | A single |
9108f8d9 | 108 | .Ql * |
f5799ae1 | 109 | as a pattern can be used to provide global |
110 | defaults for all hosts. | |
111 | The host is the | |
112 | .Ar hostname | |
9108f8d9 | 113 | argument given on the command line (i.e. the name is not converted to |
f5799ae1 | 114 | a canonicalized host name before matching). |
9108f8d9 | 115 | .Pp |
116 | See | |
117 | .Sx PATTERNS | |
118 | for more information on patterns. | |
0fff78ff | 119 | .It Cm AddressFamily |
120 | Specifies which address family to use when connecting. | |
121 | Valid arguments are | |
122 | .Dq any , | |
123 | .Dq inet | |
9108f8d9 | 124 | (use IPv4 only), or |
0fff78ff | 125 | .Dq inet6 |
996d5e62 | 126 | (use IPv6 only). |
f5799ae1 | 127 | .It Cm BatchMode |
128 | If set to | |
129 | .Dq yes , | |
130 | passphrase/password querying will be disabled. | |
131 | This option is useful in scripts and other batch jobs where no user | |
132 | is present to supply the password. | |
133 | The argument must be | |
134 | .Dq yes | |
135 | or | |
136 | .Dq no . | |
137 | The default is | |
138 | .Dq no . | |
139 | .It Cm BindAddress | |
665a873d | 140 | Use the specified address on the local machine as the source address of |
141 | the connection. | |
142 | Only useful on systems with more than one address. | |
f5799ae1 | 143 | Note that this option does not work if |
144 | .Cm UsePrivilegedPort | |
145 | is set to | |
146 | .Dq yes . | |
147 | .It Cm ChallengeResponseAuthentication | |
9108f8d9 | 148 | Specifies whether to use challenge-response authentication. |
f5799ae1 | 149 | The argument to this keyword must be |
150 | .Dq yes | |
151 | or | |
152 | .Dq no . | |
153 | The default is | |
154 | .Dq yes . | |
155 | .It Cm CheckHostIP | |
156 | If this flag is set to | |
157 | .Dq yes , | |
9108f8d9 | 158 | .Xr ssh 1 |
159 | will additionally check the host IP address in the | |
f5799ae1 | 160 | .Pa known_hosts |
161 | file. | |
162 | This allows ssh to detect if a host key changed due to DNS spoofing. | |
163 | If the option is set to | |
164 | .Dq no , | |
165 | the check will not be executed. | |
166 | The default is | |
167 | .Dq yes . | |
168 | .It Cm Cipher | |
169 | Specifies the cipher to use for encrypting the session | |
170 | in protocol version 1. | |
171 | Currently, | |
172 | .Dq blowfish , | |
173 | .Dq 3des , | |
174 | and | |
175 | .Dq des | |
176 | are supported. | |
177 | .Ar des | |
178 | is only supported in the | |
9108f8d9 | 179 | .Xr ssh 1 |
f5799ae1 | 180 | client for interoperability with legacy protocol 1 implementations |
181 | that do not support the | |
182 | .Ar 3des | |
6a9b3198 | 183 | cipher. |
184 | Its use is strongly discouraged due to cryptographic weaknesses. | |
f5799ae1 | 185 | The default is |
186 | .Dq 3des . | |
187 | .It Cm Ciphers | |
188 | Specifies the ciphers allowed for protocol version 2 | |
189 | in order of preference. | |
190 | Multiple ciphers must be comma-separated. | |
c9f39d2c | 191 | The supported ciphers are |
192 | .Dq 3des-cbc , | |
193 | .Dq aes128-cbc , | |
194 | .Dq aes192-cbc , | |
195 | .Dq aes256-cbc , | |
196 | .Dq aes128-ctr , | |
197 | .Dq aes192-ctr , | |
198 | .Dq aes256-ctr , | |
665a873d | 199 | .Dq arcfour128 , |
200 | .Dq arcfour256 , | |
c9f39d2c | 201 | .Dq arcfour , |
202 | .Dq blowfish-cbc , | |
203 | and | |
204 | .Dq cast128-cbc . | |
9108f8d9 | 205 | The default is: |
206 | .Bd -literal -offset 3n | |
91d9cdd3 | 207 | aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, |
208 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc, | |
209 | aes256-cbc,arcfour | |
f5799ae1 | 210 | .Ed |
211 | .It Cm ClearAllForwardings | |
9108f8d9 | 212 | Specifies that all local, remote, and dynamic port forwardings |
f5799ae1 | 213 | specified in the configuration files or on the command line be |
6a9b3198 | 214 | cleared. |
215 | This option is primarily useful when used from the | |
9108f8d9 | 216 | .Xr ssh 1 |
f5799ae1 | 217 | command line to clear port forwardings set in |
218 | configuration files, and is automatically set by | |
219 | .Xr scp 1 | |
220 | and | |
221 | .Xr sftp 1 . | |
222 | The argument must be | |
223 | .Dq yes | |
224 | or | |
225 | .Dq no . | |
226 | The default is | |
227 | .Dq no . | |
228 | .It Cm Compression | |
229 | Specifies whether to use compression. | |
230 | The argument must be | |
231 | .Dq yes | |
232 | or | |
233 | .Dq no . | |
234 | The default is | |
235 | .Dq no . | |
236 | .It Cm CompressionLevel | |
237 | Specifies the compression level to use if compression is enabled. | |
238 | The argument must be an integer from 1 (fast) to 9 (slow, best). | |
239 | The default level is 6, which is good for most applications. | |
240 | The meaning of the values is the same as in | |
241 | .Xr gzip 1 . | |
242 | Note that this option applies to protocol version 1 only. | |
243 | .It Cm ConnectionAttempts | |
244 | Specifies the number of tries (one per second) to make before exiting. | |
245 | The argument must be an integer. | |
246 | This may be useful in scripts if the connection sometimes fails. | |
247 | The default is 1. | |
0fff78ff | 248 | .It Cm ConnectTimeout |
9108f8d9 | 249 | Specifies the timeout (in seconds) used when connecting to the |
250 | SSH server, instead of using the default system TCP timeout. | |
0fff78ff | 251 | This value is used only when the target is down or really unreachable, |
252 | not when it refuses the connection. | |
c9f39d2c | 253 | .It Cm ControlMaster |
254 | Enables the sharing of multiple sessions over a single network connection. | |
255 | When set to | |
9108f8d9 | 256 | .Dq yes , |
257 | .Xr ssh 1 | |
c9f39d2c | 258 | will listen for connections on a control socket specified using the |
259 | .Cm ControlPath | |
260 | argument. | |
261 | Additional sessions can connect to this socket using the same | |
262 | .Cm ControlPath | |
263 | with | |
264 | .Cm ControlMaster | |
265 | set to | |
266 | .Dq no | |
267 | (the default). | |
2c06c99b | 268 | These sessions will try to reuse the master instance's network connection |
269 | rather than initiating new ones, but will fall back to connecting normally | |
270 | if the control socket does not exist, or is not listening. | |
271 | .Pp | |
c9f39d2c | 272 | Setting this to |
273 | .Dq ask | |
9108f8d9 | 274 | will cause ssh |
c9f39d2c | 275 | to listen for control connections, but require confirmation using the |
276 | .Ev SSH_ASKPASS | |
277 | program before they are accepted (see | |
278 | .Xr ssh-add 1 | |
279 | for details). | |
665a873d | 280 | If the |
281 | .Cm ControlPath | |
9108f8d9 | 282 | cannot be opened, |
283 | ssh will continue without connecting to a master instance. | |
665a873d | 284 | .Pp |
285 | X11 and | |
286 | .Xr ssh-agent 1 | |
287 | forwarding is supported over these multiplexed connections, however the | |
2c06c99b | 288 | display and agent forwarded will be the one belonging to the master |
665a873d | 289 | connection i.e. it is not possible to forward multiple displays or agents. |
290 | .Pp | |
291 | Two additional options allow for opportunistic multiplexing: try to use a | |
292 | master connection but fall back to creating a new one if one does not already | |
293 | exist. | |
294 | These options are: | |
295 | .Dq auto | |
296 | and | |
297 | .Dq autoask . | |
298 | The latter requires confirmation like the | |
299 | .Dq ask | |
300 | option. | |
c9f39d2c | 301 | .It Cm ControlPath |
665a873d | 302 | Specify the path to the control socket used for connection sharing as described |
303 | in the | |
c9f39d2c | 304 | .Cm ControlMaster |
665a873d | 305 | section above or the string |
306 | .Dq none | |
307 | to disable connection sharing. | |
308 | In the path, | |
9108f8d9 | 309 | .Ql %l |
310 | will be substituted by the local host name, | |
665a873d | 311 | .Ql %h |
312 | will be substituted by the target host name, | |
313 | .Ql %p | |
9108f8d9 | 314 | the port, and |
665a873d | 315 | .Ql %r |
316 | by the remote login username. | |
317 | It is recommended that any | |
318 | .Cm ControlPath | |
319 | used for opportunistic connection sharing include | |
9108f8d9 | 320 | at least %h, %p, and %r. |
665a873d | 321 | This ensures that shared connections are uniquely identified. |
f5799ae1 | 322 | .It Cm DynamicForward |
2c06c99b | 323 | Specifies that a TCP port on the local machine be forwarded |
f5799ae1 | 324 | over the secure channel, and the application |
325 | protocol is then used to determine where to connect to from the | |
6a9b3198 | 326 | remote machine. |
2c06c99b | 327 | .Pp |
328 | The argument must be | |
329 | .Sm off | |
330 | .Oo Ar bind_address : Oc Ar port . | |
331 | .Sm on | |
332 | IPv6 addresses can be specified by enclosing addresses in square brackets or | |
333 | by using an alternative syntax: | |
334 | .Oo Ar bind_address Ns / Oc Ns Ar port . | |
335 | By default, the local port is bound in accordance with the | |
336 | .Cm GatewayPorts | |
337 | setting. | |
338 | However, an explicit | |
339 | .Ar bind_address | |
340 | may be used to bind the connection to a specific address. | |
341 | The | |
342 | .Ar bind_address | |
343 | of | |
344 | .Dq localhost | |
345 | indicates that the listening port be bound for local use only, while an | |
346 | empty address or | |
347 | .Sq * | |
348 | indicates that the port should be available from all interfaces. | |
349 | .Pp | |
0fff78ff | 350 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
9108f8d9 | 351 | .Xr ssh 1 |
0fff78ff | 352 | will act as a SOCKS server. |
f5799ae1 | 353 | Multiple forwardings may be specified, and |
6a9b3198 | 354 | additional forwardings can be given on the command line. |
355 | Only the superuser can forward privileged ports. | |
0fff78ff | 356 | .It Cm EnableSSHKeysign |
357 | Setting this option to | |
358 | .Dq yes | |
359 | in the global client configuration file | |
360 | .Pa /etc/ssh/ssh_config | |
361 | enables the use of the helper program | |
362 | .Xr ssh-keysign 8 | |
363 | during | |
364 | .Cm HostbasedAuthentication . | |
365 | The argument must be | |
366 | .Dq yes | |
367 | or | |
368 | .Dq no . | |
369 | The default is | |
370 | .Dq no . | |
cdd66111 | 371 | This option should be placed in the non-hostspecific section. |
0fff78ff | 372 | See |
373 | .Xr ssh-keysign 8 | |
374 | for more information. | |
f5799ae1 | 375 | .It Cm EscapeChar |
376 | Sets the escape character (default: | |
377 | .Ql ~ ) . | |
378 | The escape character can also | |
379 | be set on the command line. | |
380 | The argument should be a single character, | |
381 | .Ql ^ | |
382 | followed by a letter, or | |
383 | .Dq none | |
384 | to disable the escape | |
385 | character entirely (making the connection transparent for binary | |
386 | data). | |
9108f8d9 | 387 | .It Cm ExitOnForwardFailure |
388 | Specifies whether | |
389 | .Xr ssh 1 | |
390 | should terminate the connection if it cannot set up all requested | |
d4487008 | 391 | dynamic, tunnel, local, and remote port forwardings. |
9108f8d9 | 392 | The argument must be |
393 | .Dq yes | |
394 | or | |
395 | .Dq no . | |
396 | The default is | |
397 | .Dq no . | |
f5799ae1 | 398 | .It Cm ForwardAgent |
399 | Specifies whether the connection to the authentication agent (if any) | |
400 | will be forwarded to the remote machine. | |
401 | The argument must be | |
402 | .Dq yes | |
403 | or | |
404 | .Dq no . | |
405 | The default is | |
406 | .Dq no . | |
41b2f314 | 407 | .Pp |
6a9b3198 | 408 | Agent forwarding should be enabled with caution. |
409 | Users with the ability to bypass file permissions on the remote host | |
410 | (for the agent's Unix-domain socket) | |
411 | can access the local agent through the forwarded connection. | |
412 | An attacker cannot obtain key material from the agent, | |
41b2f314 | 413 | however they can perform operations on the keys that enable them to |
414 | authenticate using the identities loaded into the agent. | |
f5799ae1 | 415 | .It Cm ForwardX11 |
416 | Specifies whether X11 connections will be automatically redirected | |
417 | over the secure channel and | |
418 | .Ev DISPLAY | |
419 | set. | |
420 | The argument must be | |
421 | .Dq yes | |
422 | or | |
423 | .Dq no . | |
424 | The default is | |
425 | .Dq no . | |
41b2f314 | 426 | .Pp |
6a9b3198 | 427 | X11 forwarding should be enabled with caution. |
428 | Users with the ability to bypass file permissions on the remote host | |
cdd66111 | 429 | (for the user's X11 authorization database) |
6a9b3198 | 430 | can access the local X11 display through the forwarded connection. |
cdd66111 | 431 | An attacker may then be able to perform activities such as keystroke monitoring |
432 | if the | |
433 | .Cm ForwardX11Trusted | |
434 | option is also enabled. | |
435 | .It Cm ForwardX11Trusted | |
c9f39d2c | 436 | If this option is set to |
9108f8d9 | 437 | .Dq yes , |
438 | remote X11 clients will have full access to the original X11 display. | |
996d5e62 | 439 | .Pp |
cdd66111 | 440 | If this option is set to |
9108f8d9 | 441 | .Dq no , |
442 | remote X11 clients will be considered untrusted and prevented | |
cdd66111 | 443 | from stealing or tampering with data belonging to trusted X11 |
444 | clients. | |
996d5e62 | 445 | Furthermore, the |
446 | .Xr xauth 1 | |
447 | token used for the session will be set to expire after 20 minutes. | |
448 | Remote clients will be refused access after this time. | |
cdd66111 | 449 | .Pp |
450 | The default is | |
451 | .Dq no . | |
452 | .Pp | |
453 | See the X11 SECURITY extension specification for full details on | |
454 | the restrictions imposed on untrusted clients. | |
f5799ae1 | 455 | .It Cm GatewayPorts |
456 | Specifies whether remote hosts are allowed to connect to local | |
457 | forwarded ports. | |
458 | By default, | |
9108f8d9 | 459 | .Xr ssh 1 |
6a9b3198 | 460 | binds local port forwardings to the loopback address. |
461 | This prevents other remote hosts from connecting to forwarded ports. | |
f5799ae1 | 462 | .Cm GatewayPorts |
9108f8d9 | 463 | can be used to specify that ssh |
f5799ae1 | 464 | should bind local port forwardings to the wildcard address, |
465 | thus allowing remote hosts to connect to forwarded ports. | |
466 | The argument must be | |
467 | .Dq yes | |
468 | or | |
469 | .Dq no . | |
470 | The default is | |
471 | .Dq no . | |
472 | .It Cm GlobalKnownHostsFile | |
473 | Specifies a file to use for the global | |
474 | host key database instead of | |
475 | .Pa /etc/ssh/ssh_known_hosts . | |
0fff78ff | 476 | .It Cm GSSAPIAuthentication |
cdd66111 | 477 | Specifies whether user authentication based on GSSAPI is allowed. |
0fff78ff | 478 | The default is |
cdd66111 | 479 | .Dq no . |
0fff78ff | 480 | Note that this option applies to protocol version 2 only. |
f97edba6 | 481 | .It Cm GSSAPIKeyExchange |
482 | Specifies whether key exchange based on GSSAPI may be used. When using | |
483 | GSSAPI key exchange the server need not have a host key. | |
484 | The default is | |
485 | .Dq no . | |
486 | Note that this option applies to protocol version 2 only. | |
487 | .It Cm GSSAPIClientIdentity | |
488 | If set, specifies the GSSAPI client identity that ssh should use when | |
489 | connecting to the server. The default is unset, which means that the default | |
490 | identity will be used. | |
0fff78ff | 491 | .It Cm GSSAPIDelegateCredentials |
492 | Forward (delegate) credentials to the server. | |
493 | The default is | |
494 | .Dq no . | |
f97edba6 | 495 | Note that this option applies to protocol version 2 connections using GSSAPI. |
496 | .It Cm GSSAPIRenewalForcesRekey | |
497 | If set to | |
498 | .Dq yes | |
499 | then renewal of the client's GSSAPI credentials will force the rekeying of the | |
500 | ssh connection. With a compatible server, this can delegate the renewed | |
501 | credentials to a session on the server. | |
502 | The default is | |
503 | .Dq no . | |
504 | .It Cm GSSAPITrustDns | |
505 | Set to | |
506 | .Dq yes to indicate that the DNS is trusted to securely canonicalize | |
507 | the name of the host being connected to. If | |
508 | .Dq no, the hostname entered on the | |
509 | command line will be passed untouched to the GSSAPI library. | |
510 | The default is | |
511 | .Dq no . | |
512 | This option only applies to protocol version 2 connections using GSSAPI. | |
996d5e62 | 513 | .It Cm HashKnownHosts |
514 | Indicates that | |
9108f8d9 | 515 | .Xr ssh 1 |
996d5e62 | 516 | should hash host names and addresses when they are added to |
665a873d | 517 | .Pa ~/.ssh/known_hosts . |
996d5e62 | 518 | These hashed names may be used normally by |
9108f8d9 | 519 | .Xr ssh 1 |
996d5e62 | 520 | and |
9108f8d9 | 521 | .Xr sshd 8 , |
996d5e62 | 522 | but they do not reveal identifying information should the file's contents |
523 | be disclosed. | |
524 | The default is | |
525 | .Dq no . | |
9108f8d9 | 526 | Note that existing names and addresses in known hosts files |
527 | will not be converted automatically, | |
528 | but may be manually hashed using | |
996d5e62 | 529 | .Xr ssh-keygen 1 . |
f5799ae1 | 530 | .It Cm HostbasedAuthentication |
531 | Specifies whether to try rhosts based authentication with public key | |
532 | authentication. | |
533 | The argument must be | |
534 | .Dq yes | |
535 | or | |
536 | .Dq no . | |
537 | The default is | |
538 | .Dq no . | |
539 | This option applies to protocol version 2 only and | |
540 | is similar to | |
541 | .Cm RhostsRSAAuthentication . | |
542 | .It Cm HostKeyAlgorithms | |
543 | Specifies the protocol version 2 host key algorithms | |
544 | that the client wants to use in order of preference. | |
545 | The default for this option is: | |
546 | .Dq ssh-rsa,ssh-dss . | |
547 | .It Cm HostKeyAlias | |
548 | Specifies an alias that should be used instead of the | |
549 | real host name when looking up or saving the host key | |
550 | in the host key database files. | |
9108f8d9 | 551 | This option is useful for tunneling SSH connections |
f5799ae1 | 552 | or for multiple servers running on a single host. |
553 | .It Cm HostName | |
554 | Specifies the real host name to log into. | |
555 | This can be used to specify nicknames or abbreviations for hosts. | |
9108f8d9 | 556 | The default is the name given on the command line. |
f5799ae1 | 557 | Numeric IP addresses are also permitted (both on the command line and in |
558 | .Cm HostName | |
559 | specifications). | |
99be0775 | 560 | .It Cm IdentitiesOnly |
561 | Specifies that | |
9108f8d9 | 562 | .Xr ssh 1 |
99be0775 | 563 | should only use the authentication identity files configured in the |
c9f39d2c | 564 | .Nm |
99be0775 | 565 | files, |
9108f8d9 | 566 | even if |
567 | .Xr ssh-agent 1 | |
99be0775 | 568 | offers more identities. |
569 | The argument to this keyword must be | |
570 | .Dq yes | |
571 | or | |
572 | .Dq no . | |
9108f8d9 | 573 | This option is intended for situations where ssh-agent |
99be0775 | 574 | offers many different identities. |
575 | The default is | |
576 | .Dq no . | |
2c06c99b | 577 | .It Cm IdentityFile |
578 | Specifies a file from which the user's RSA or DSA authentication identity | |
579 | is read. | |
580 | The default is | |
581 | .Pa ~/.ssh/identity | |
582 | for protocol version 1, and | |
583 | .Pa ~/.ssh/id_rsa | |
584 | and | |
585 | .Pa ~/.ssh/id_dsa | |
586 | for protocol version 2. | |
587 | Additionally, any identities represented by the authentication agent | |
588 | will be used for authentication. | |
9108f8d9 | 589 | .Pp |
2c06c99b | 590 | The file name may use the tilde |
9108f8d9 | 591 | syntax to refer to a user's home directory or one of the following |
592 | escape characters: | |
593 | .Ql %d | |
594 | (local user's home directory), | |
595 | .Ql %u | |
596 | (local user name), | |
597 | .Ql %l | |
598 | (local host name), | |
599 | .Ql %h | |
600 | (remote host name) or | |
601 | .Ql %r | |
602 | (remote user name). | |
603 | .Pp | |
2c06c99b | 604 | It is possible to have |
605 | multiple identity files specified in configuration files; all these | |
606 | identities will be tried in sequence. | |
47686178 | 607 | .It Cm KbdInteractiveAuthentication |
608 | Specifies whether to use keyboard-interactive authentication. | |
609 | The argument to this keyword must be | |
610 | .Dq yes | |
611 | or | |
612 | .Dq no . | |
613 | The default is | |
614 | .Dq yes . | |
996d5e62 | 615 | .It Cm KbdInteractiveDevices |
616 | Specifies the list of methods to use in keyboard-interactive authentication. | |
617 | Multiple method names must be comma-separated. | |
618 | The default is to use the server specified list. | |
9108f8d9 | 619 | The methods available vary depending on what the server supports. |
620 | For an OpenSSH server, | |
621 | it may be zero or more of: | |
622 | .Dq bsdauth , | |
623 | .Dq pam , | |
624 | and | |
625 | .Dq skey . | |
2c06c99b | 626 | .It Cm LocalCommand |
627 | Specifies a command to execute on the local machine after successfully | |
628 | connecting to the server. | |
629 | The command string extends to the end of the line, and is executed with | |
47686178 | 630 | the user's shell. |
22616013 | 631 | The following escape character substitutions will be performed: |
632 | .Ql %d | |
633 | (local user's home directory), | |
634 | .Ql %h | |
635 | (remote host name), | |
636 | .Ql %l | |
637 | (local host name), | |
638 | .Ql %n | |
639 | (host name as provided on the command line), | |
640 | .Ql %p | |
641 | (remote port), | |
642 | .Ql %r | |
643 | (remote user name) or | |
644 | .Ql %u | |
645 | (local user name). | |
2c06c99b | 646 | This directive is ignored unless |
647 | .Cm PermitLocalCommand | |
648 | has been enabled. | |
f5799ae1 | 649 | .It Cm LocalForward |
2c06c99b | 650 | Specifies that a TCP port on the local machine be forwarded over |
f5799ae1 | 651 | the secure channel to the specified host and port from the remote machine. |
dec6d9fe | 652 | The first argument must be |
996d5e62 | 653 | .Sm off |
dec6d9fe | 654 | .Oo Ar bind_address : Oc Ar port |
996d5e62 | 655 | .Sm on |
dec6d9fe | 656 | and the second argument must be |
657 | .Ar host : Ns Ar hostport . | |
996d5e62 | 658 | IPv6 addresses can be specified by enclosing addresses in square brackets or |
659 | by using an alternative syntax: | |
dec6d9fe | 660 | .Oo Ar bind_address Ns / Oc Ns Ar port |
661 | and | |
662 | .Ar host Ns / Ns Ar hostport . | |
996d5e62 | 663 | Multiple forwardings may be specified, and additional forwardings can be |
664 | given on the command line. | |
f5799ae1 | 665 | Only the superuser can forward privileged ports. |
996d5e62 | 666 | By default, the local port is bound in accordance with the |
667 | .Cm GatewayPorts | |
668 | setting. | |
669 | However, an explicit | |
670 | .Ar bind_address | |
671 | may be used to bind the connection to a specific address. | |
672 | The | |
673 | .Ar bind_address | |
674 | of | |
675 | .Dq localhost | |
676 | indicates that the listening port be bound for local use only, while an | |
677 | empty address or | |
678 | .Sq * | |
679 | indicates that the port should be available from all interfaces. | |
f5799ae1 | 680 | .It Cm LogLevel |
681 | Gives the verbosity level that is used when logging messages from | |
9108f8d9 | 682 | .Xr ssh 1 . |
f5799ae1 | 683 | The possible values are: |
9108f8d9 | 684 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
6a9b3198 | 685 | The default is INFO. |
686 | DEBUG and DEBUG1 are equivalent. | |
687 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. | |
f5799ae1 | 688 | .It Cm MACs |
689 | Specifies the MAC (message authentication code) algorithms | |
690 | in order of preference. | |
691 | The MAC algorithm is used in protocol version 2 | |
692 | for data integrity protection. | |
693 | Multiple algorithms must be comma-separated. | |
9108f8d9 | 694 | The default is: |
d4487008 | 695 | .Bd -literal -offset indent |
696 | hmac-md5,hmac-sha1,umac-64@openssh.com, | |
697 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 | |
698 | .Ed | |
f5799ae1 | 699 | .It Cm NoHostAuthenticationForLocalhost |
700 | This option can be used if the home directory is shared across machines. | |
701 | In this case localhost will refer to a different machine on each of | |
702 | the machines and the user will get many warnings about changed host keys. | |
703 | However, this option disables host authentication for localhost. | |
704 | The argument to this keyword must be | |
705 | .Dq yes | |
706 | or | |
707 | .Dq no . | |
708 | The default is to check the host key for localhost. | |
709 | .It Cm NumberOfPasswordPrompts | |
710 | Specifies the number of password prompts before giving up. | |
711 | The argument to this keyword must be an integer. | |
9108f8d9 | 712 | The default is 3. |
f5799ae1 | 713 | .It Cm PasswordAuthentication |
714 | Specifies whether to use password authentication. | |
715 | The argument to this keyword must be | |
716 | .Dq yes | |
717 | or | |
718 | .Dq no . | |
719 | The default is | |
720 | .Dq yes . | |
2c06c99b | 721 | .It Cm PermitLocalCommand |
722 | Allow local command execution via the | |
723 | .Ic LocalCommand | |
724 | option or using the | |
725 | .Ic !\& Ns Ar command | |
726 | escape sequence in | |
727 | .Xr ssh 1 . | |
728 | The argument must be | |
729 | .Dq yes | |
730 | or | |
731 | .Dq no . | |
732 | The default is | |
733 | .Dq no . | |
f5799ae1 | 734 | .It Cm Port |
735 | Specifies the port number to connect on the remote host. | |
9108f8d9 | 736 | The default is 22. |
f5799ae1 | 737 | .It Cm PreferredAuthentications |
738 | Specifies the order in which the client should try protocol 2 | |
0fff78ff | 739 | authentication methods. |
dec6d9fe | 740 | This allows a client to prefer one method (e.g.\& |
f5799ae1 | 741 | .Cm keyboard-interactive ) |
dec6d9fe | 742 | over another method (e.g.\& |
f5799ae1 | 743 | .Cm password ) |
744 | The default for this option is: | |
9108f8d9 | 745 | .Do gssapi-with-mic , |
746 | hostbased, | |
747 | publickey, | |
748 | keyboard-interactive, | |
749 | password | |
750 | .Dc . | |
f5799ae1 | 751 | .It Cm Protocol |
752 | Specifies the protocol versions | |
9108f8d9 | 753 | .Xr ssh 1 |
f5799ae1 | 754 | should support in order of preference. |
755 | The possible values are | |
9108f8d9 | 756 | .Sq 1 |
f5799ae1 | 757 | and |
9108f8d9 | 758 | .Sq 2 . |
f5799ae1 | 759 | Multiple versions must be comma-separated. |
760 | The default is | |
761 | .Dq 2,1 . | |
9108f8d9 | 762 | This means that ssh |
f5799ae1 | 763 | tries version 2 and falls back to version 1 |
764 | if version 2 is not available. | |
765 | .It Cm ProxyCommand | |
766 | Specifies the command to use to connect to the server. | |
767 | The command | |
768 | string extends to the end of the line, and is executed with | |
47686178 | 769 | the user's shell. |
f5799ae1 | 770 | In the command string, |
771 | .Ql %h | |
772 | will be substituted by the host name to | |
773 | connect and | |
774 | .Ql %p | |
775 | by the port. | |
776 | The command can be basically anything, | |
777 | and should read from its standard input and write to its standard output. | |
778 | It should eventually connect an | |
779 | .Xr sshd 8 | |
780 | server running on some machine, or execute | |
781 | .Ic sshd -i | |
782 | somewhere. | |
783 | Host key management will be done using the | |
784 | HostName of the host being connected (defaulting to the name typed by | |
785 | the user). | |
6a9b3198 | 786 | Setting the command to |
787 | .Dq none | |
788 | disables this option entirely. | |
f5799ae1 | 789 | Note that |
790 | .Cm CheckHostIP | |
791 | is not available for connects with a proxy command. | |
792 | .Pp | |
665a873d | 793 | This directive is useful in conjunction with |
794 | .Xr nc 1 | |
795 | and its proxy support. | |
796 | For example, the following directive would connect via an HTTP proxy at | |
797 | 192.0.2.0: | |
798 | .Bd -literal -offset 3n | |
799 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p | |
800 | .Ed | |
f5799ae1 | 801 | .It Cm PubkeyAuthentication |
802 | Specifies whether to try public key authentication. | |
803 | The argument to this keyword must be | |
804 | .Dq yes | |
805 | or | |
806 | .Dq no . | |
807 | The default is | |
808 | .Dq yes . | |
809 | This option applies to protocol version 2 only. | |
2c06c99b | 810 | .It Cm RekeyLimit |
811 | Specifies the maximum amount of data that may be transmitted before the | |
812 | session key is renegotiated. | |
813 | The argument is the number of bytes, with an optional suffix of | |
814 | .Sq K , | |
815 | .Sq M , | |
816 | or | |
817 | .Sq G | |
818 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. | |
819 | The default is between | |
9108f8d9 | 820 | .Sq 1G |
2c06c99b | 821 | and |
9108f8d9 | 822 | .Sq 4G , |
2c06c99b | 823 | depending on the cipher. |
824 | This option applies to protocol version 2 only. | |
f5799ae1 | 825 | .It Cm RemoteForward |
2c06c99b | 826 | Specifies that a TCP port on the remote machine be forwarded over |
f5799ae1 | 827 | the secure channel to the specified host and port from the local machine. |
dec6d9fe | 828 | The first argument must be |
996d5e62 | 829 | .Sm off |
dec6d9fe | 830 | .Oo Ar bind_address : Oc Ar port |
996d5e62 | 831 | .Sm on |
dec6d9fe | 832 | and the second argument must be |
833 | .Ar host : Ns Ar hostport . | |
834 | IPv6 addresses can be specified by enclosing addresses in square brackets | |
835 | or by using an alternative syntax: | |
836 | .Oo Ar bind_address Ns / Oc Ns Ar port | |
837 | and | |
838 | .Ar host Ns / Ns Ar hostport . | |
f5799ae1 | 839 | Multiple forwardings may be specified, and additional |
840 | forwardings can be given on the command line. | |
91d9cdd3 | 841 | Privileged ports can be forwarded only when |
842 | logging in as root on the remote machine. | |
843 | .Pp | |
844 | If the | |
845 | .Ar port | |
846 | argument is | |
847 | .Ql 0 , | |
848 | the listen port will be dynamically allocated on the server and reported | |
849 | to the client at run time. | |
996d5e62 | 850 | .Pp |
851 | If the | |
852 | .Ar bind_address | |
853 | is not specified, the default is to only bind to loopback addresses. | |
854 | If the | |
855 | .Ar bind_address | |
856 | is | |
857 | .Ql * | |
858 | or an empty string, then the forwarding is requested to listen on all | |
859 | interfaces. | |
860 | Specifying a remote | |
861 | .Ar bind_address | |
862 | will only succeed if the server's | |
863 | .Cm GatewayPorts | |
864 | option is enabled (see | |
865 | .Xr sshd_config 5 ) . | |
f5799ae1 | 866 | .It Cm RhostsRSAAuthentication |
867 | Specifies whether to try rhosts based authentication with RSA host | |
868 | authentication. | |
869 | The argument must be | |
870 | .Dq yes | |
871 | or | |
872 | .Dq no . | |
873 | The default is | |
874 | .Dq no . | |
875 | This option applies to protocol version 1 only and requires | |
9108f8d9 | 876 | .Xr ssh 1 |
f5799ae1 | 877 | to be setuid root. |
878 | .It Cm RSAAuthentication | |
879 | Specifies whether to try RSA authentication. | |
880 | The argument to this keyword must be | |
881 | .Dq yes | |
882 | or | |
883 | .Dq no . | |
884 | RSA authentication will only be | |
885 | attempted if the identity file exists, or an authentication agent is | |
886 | running. | |
887 | The default is | |
888 | .Dq yes . | |
889 | Note that this option applies to protocol version 1 only. | |
c9f39d2c | 890 | .It Cm SendEnv |
891 | Specifies what variables from the local | |
892 | .Xr environ 7 | |
893 | should be sent to the server. | |
9108f8d9 | 894 | Note that environment passing is only supported for protocol 2. |
895 | The server must also support it, and the server must be configured to | |
c9f39d2c | 896 | accept these environment variables. |
897 | Refer to | |
898 | .Cm AcceptEnv | |
899 | in | |
900 | .Xr sshd_config 5 | |
901 | for how to configure the server. | |
9108f8d9 | 902 | Variables are specified by name, which may contain wildcard characters. |
c9f39d2c | 903 | Multiple environment variables may be separated by whitespace or spread |
904 | across multiple | |
905 | .Cm SendEnv | |
906 | directives. | |
907 | The default is not to send any environment variables. | |
9108f8d9 | 908 | .Pp |
909 | See | |
910 | .Sx PATTERNS | |
911 | for more information on patterns. | |
cdd66111 | 912 | .It Cm ServerAliveCountMax |
2c06c99b | 913 | Sets the number of server alive messages (see below) which may be |
cdd66111 | 914 | sent without |
9108f8d9 | 915 | .Xr ssh 1 |
cdd66111 | 916 | receiving any messages back from the server. |
917 | If this threshold is reached while server alive messages are being sent, | |
9108f8d9 | 918 | ssh will disconnect from the server, terminating the session. |
cdd66111 | 919 | It is important to note that the use of server alive messages is very |
920 | different from | |
921 | .Cm TCPKeepAlive | |
922 | (below). | |
923 | The server alive messages are sent through the encrypted channel | |
924 | and therefore will not be spoofable. | |
925 | The TCP keepalive option enabled by | |
926 | .Cm TCPKeepAlive | |
927 | is spoofable. | |
928 | The server alive mechanism is valuable when the client or | |
929 | server depend on knowing when a connection has become inactive. | |
930 | .Pp | |
931 | The default value is 3. | |
932 | If, for example, | |
933 | .Cm ServerAliveInterval | |
9108f8d9 | 934 | (see below) is set to 15 and |
cdd66111 | 935 | .Cm ServerAliveCountMax |
9108f8d9 | 936 | is left at the default, if the server becomes unresponsive, |
937 | ssh will disconnect after approximately 45 seconds. | |
938 | This option applies to protocol version 2 only. | |
2c06c99b | 939 | .It Cm ServerAliveInterval |
940 | Sets a timeout interval in seconds after which if no data has been received | |
941 | from the server, | |
9108f8d9 | 942 | .Xr ssh 1 |
2c06c99b | 943 | will send a message through the encrypted |
944 | channel to request a response from the server. | |
945 | The default | |
946 | is 0, indicating that these messages will not be sent to the server. | |
947 | This option applies to protocol version 2 only. | |
f5799ae1 | 948 | .It Cm SmartcardDevice |
0fff78ff | 949 | Specifies which smartcard device to use. |
950 | The argument to this keyword is the device | |
9108f8d9 | 951 | .Xr ssh 1 |
f5799ae1 | 952 | should use to communicate with a smartcard used for storing the user's |
0fff78ff | 953 | private RSA key. |
954 | By default, no device is specified and smartcard support is not activated. | |
f5799ae1 | 955 | .It Cm StrictHostKeyChecking |
956 | If this flag is set to | |
957 | .Dq yes , | |
9108f8d9 | 958 | .Xr ssh 1 |
f5799ae1 | 959 | will never automatically add host keys to the |
665a873d | 960 | .Pa ~/.ssh/known_hosts |
f5799ae1 | 961 | file, and refuses to connect to hosts whose host key has changed. |
962 | This provides maximum protection against trojan horse attacks, | |
9108f8d9 | 963 | though it can be annoying when the |
f5799ae1 | 964 | .Pa /etc/ssh/ssh_known_hosts |
9108f8d9 | 965 | file is poorly maintained or when connections to new hosts are |
f5799ae1 | 966 | frequently made. |
967 | This option forces the user to manually | |
968 | add all new hosts. | |
969 | If this flag is set to | |
970 | .Dq no , | |
9108f8d9 | 971 | ssh will automatically add new host keys to the |
f5799ae1 | 972 | user known hosts files. |
973 | If this flag is set to | |
974 | .Dq ask , | |
975 | new host keys | |
976 | will be added to the user known host files only after the user | |
977 | has confirmed that is what they really want to do, and | |
9108f8d9 | 978 | ssh will refuse to connect to hosts whose host key has changed. |
f5799ae1 | 979 | The host keys of |
980 | known hosts will be verified automatically in all cases. | |
981 | The argument must be | |
982 | .Dq yes , | |
9108f8d9 | 983 | .Dq no , |
f5799ae1 | 984 | or |
985 | .Dq ask . | |
986 | The default is | |
987 | .Dq ask . | |
cdd66111 | 988 | .It Cm TCPKeepAlive |
989 | Specifies whether the system should send TCP keepalive messages to the | |
990 | other side. | |
991 | If they are sent, death of the connection or crash of one | |
992 | of the machines will be properly noticed. | |
993 | However, this means that | |
994 | connections will die if the route is down temporarily, and some people | |
995 | find it annoying. | |
996 | .Pp | |
997 | The default is | |
998 | .Dq yes | |
999 | (to send TCP keepalive messages), and the client will notice | |
1000 | if the network goes down or the remote host dies. | |
1001 | This is important in scripts, and many users want it too. | |
1002 | .Pp | |
1003 | To disable TCP keepalive messages, the value should be set to | |
1004 | .Dq no . | |
2c06c99b | 1005 | .It Cm Tunnel |
9108f8d9 | 1006 | Request |
2c06c99b | 1007 | .Xr tun 4 |
1008 | device forwarding between the client and the server. | |
2c06c99b | 1009 | The argument must be |
1010 | .Dq yes , | |
9108f8d9 | 1011 | .Dq point-to-point |
1012 | (layer 3), | |
2c06c99b | 1013 | .Dq ethernet |
9108f8d9 | 1014 | (layer 2), |
2c06c99b | 1015 | or |
1016 | .Dq no . | |
9108f8d9 | 1017 | Specifying |
1018 | .Dq yes | |
1019 | requests the default tunnel mode, which is | |
1020 | .Dq point-to-point . | |
2c06c99b | 1021 | The default is |
1022 | .Dq no . | |
1023 | .It Cm TunnelDevice | |
9108f8d9 | 1024 | Specifies the |
2c06c99b | 1025 | .Xr tun 4 |
9108f8d9 | 1026 | devices to open on the client |
1027 | .Pq Ar local_tun | |
1028 | and the server | |
1029 | .Pq Ar remote_tun . | |
1030 | .Pp | |
1031 | The argument must be | |
1032 | .Sm off | |
1033 | .Ar local_tun Op : Ar remote_tun . | |
1034 | .Sm on | |
1035 | The devices may be specified by numerical ID or the keyword | |
1036 | .Dq any , | |
1037 | which uses the next available tunnel device. | |
1038 | If | |
1039 | .Ar remote_tun | |
1040 | is not specified, it defaults to | |
1041 | .Dq any . | |
1042 | The default is | |
1043 | .Dq any:any . | |
f5799ae1 | 1044 | .It Cm UsePrivilegedPort |
1045 | Specifies whether to use a privileged port for outgoing connections. | |
1046 | The argument must be | |
1047 | .Dq yes | |
1048 | or | |
1049 | .Dq no . | |
1050 | The default is | |
1051 | .Dq no . | |
41b2f314 | 1052 | If set to |
9108f8d9 | 1053 | .Dq yes , |
1054 | .Xr ssh 1 | |
41b2f314 | 1055 | must be setuid root. |
f5799ae1 | 1056 | Note that this option must be set to |
1057 | .Dq yes | |
0fff78ff | 1058 | for |
f5799ae1 | 1059 | .Cm RhostsRSAAuthentication |
0fff78ff | 1060 | with older servers. |
f5799ae1 | 1061 | .It Cm User |
1062 | Specifies the user to log in as. | |
1063 | This can be useful when a different user name is used on different machines. | |
1064 | This saves the trouble of | |
1065 | having to remember to give the user name on the command line. | |
1066 | .It Cm UserKnownHostsFile | |
1067 | Specifies a file to use for the user | |
1068 | host key database instead of | |
665a873d | 1069 | .Pa ~/.ssh/known_hosts . |
0fff78ff | 1070 | .It Cm VerifyHostKeyDNS |
1071 | Specifies whether to verify the remote key using DNS and SSHFP resource | |
1072 | records. | |
cdd66111 | 1073 | If this option is set to |
1074 | .Dq yes , | |
1075 | the client will implicitly trust keys that match a secure fingerprint | |
1076 | from DNS. | |
1077 | Insecure fingerprints will be handled as if this option was set to | |
1078 | .Dq ask . | |
1079 | If this option is set to | |
1080 | .Dq ask , | |
1081 | information on fingerprint match will be displayed, but the user will still | |
1082 | need to confirm new host keys according to the | |
1083 | .Cm StrictHostKeyChecking | |
1084 | option. | |
1085 | The argument must be | |
1086 | .Dq yes , | |
9108f8d9 | 1087 | .Dq no , |
cdd66111 | 1088 | or |
1089 | .Dq ask . | |
0fff78ff | 1090 | The default is |
1091 | .Dq no . | |
1092 | Note that this option applies to protocol version 2 only. | |
9108f8d9 | 1093 | .Pp |
1094 | See also | |
1095 | .Sx VERIFYING HOST KEYS | |
1096 | in | |
1097 | .Xr ssh 1 . | |
22616013 | 1098 | .It Cm VisualHostKey |
1099 | If this flag is set to | |
1100 | .Dq yes , | |
1101 | an ASCII art representation of the remote host key fingerprint is | |
91d9cdd3 | 1102 | printed in addition to the hex fingerprint string at login and |
1103 | for unknown host keys. | |
22616013 | 1104 | If this flag is set to |
1105 | .Dq no , | |
91d9cdd3 | 1106 | no fingerprint strings are printed at login and |
1107 | only the hex fingerprint string will be printed for unknown host keys. | |
22616013 | 1108 | The default is |
1109 | .Dq no . | |
f5799ae1 | 1110 | .It Cm XAuthLocation |
41b2f314 | 1111 | Specifies the full pathname of the |
f5799ae1 | 1112 | .Xr xauth 1 |
1113 | program. | |
1114 | The default is | |
1115 | .Pa /usr/X11R6/bin/xauth . | |
1116 | .El | |
9108f8d9 | 1117 | .Sh PATTERNS |
1118 | A | |
1119 | .Em pattern | |
1120 | consists of zero or more non-whitespace characters, | |
1121 | .Sq * | |
1122 | (a wildcard that matches zero or more characters), | |
1123 | or | |
1124 | .Sq ?\& | |
1125 | (a wildcard that matches exactly one character). | |
1126 | For example, to specify a set of declarations for any host in the | |
1127 | .Dq .co.uk | |
1128 | set of domains, | |
1129 | the following pattern could be used: | |
1130 | .Pp | |
1131 | .Dl Host *.co.uk | |
1132 | .Pp | |
1133 | The following pattern | |
1134 | would match any host in the 192.168.0.[0-9] network range: | |
1135 | .Pp | |
1136 | .Dl Host 192.168.0.? | |
1137 | .Pp | |
1138 | A | |
1139 | .Em pattern-list | |
1140 | is a comma-separated list of patterns. | |
1141 | Patterns within pattern-lists may be negated | |
1142 | by preceding them with an exclamation mark | |
1143 | .Pq Sq !\& . | |
1144 | For example, | |
1145 | to allow a key to be used from anywhere within an organisation | |
1146 | except from the | |
1147 | .Dq dialup | |
1148 | pool, | |
1149 | the following entry (in authorized_keys) could be used: | |
1150 | .Pp | |
1151 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" | |
f5799ae1 | 1152 | .Sh FILES |
1153 | .Bl -tag -width Ds | |
665a873d | 1154 | .It Pa ~/.ssh/config |
f5799ae1 | 1155 | This is the per-user configuration file. |
1156 | The format of this file is described above. | |
9108f8d9 | 1157 | This file is used by the SSH client. |
c9f39d2c | 1158 | Because of the potential for abuse, this file must have strict permissions: |
1159 | read/write for the user, and not accessible by others. | |
f5799ae1 | 1160 | .It Pa /etc/ssh/ssh_config |
1161 | Systemwide configuration file. | |
1162 | This file provides defaults for those | |
1163 | values that are not specified in the user's configuration file, and | |
1164 | for those users who do not have a configuration file. | |
1165 | This file must be world-readable. | |
1166 | .El | |
0fff78ff | 1167 | .Sh SEE ALSO |
1168 | .Xr ssh 1 | |
f5799ae1 | 1169 | .Sh AUTHORS |
1170 | OpenSSH is a derivative of the original and free | |
1171 | ssh 1.2.12 release by Tatu Ylonen. | |
1172 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
1173 | Theo de Raadt and Dug Song | |
1174 | removed many bugs, re-added newer features and | |
1175 | created OpenSSH. | |
1176 | Markus Friedl contributed the support for SSH | |
1177 | protocol versions 1.5 and 2.0. |