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884dc78b | 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 | .\" | |
5262cbfb | 37 | .\" $OpenBSD: ssh_config.5,v 1.119 2009/02/22 23:50:57 djm Exp $ |
38 | .Dd $Mdocdate: February 22 2009 $ | |
884dc78b | 39 | .Dt SSH_CONFIG 5 |
40 | .Os | |
41 | .Sh NAME | |
42 | .Nm ssh_config | |
43 | .Nd OpenSSH SSH client configuration files | |
44 | .Sh SYNOPSIS | |
0b90ac93 | 45 | .Nm ~/.ssh/config |
46 | .Nm /etc/ssh/ssh_config | |
884dc78b | 47 | .Sh DESCRIPTION |
30460aeb | 48 | .Xr ssh 1 |
884dc78b | 49 | obtains configuration data from the following sources in |
50 | the following order: | |
30460aeb | 51 | .Pp |
d03f4262 | 52 | .Bl -enum -offset indent -compact |
53 | .It | |
54 | command-line options | |
55 | .It | |
44a053a3 | 56 | user's configuration file |
2ce0bfe4 | 57 | .Pq Pa ~/.ssh/config |
d03f4262 | 58 | .It |
d6862c36 | 59 | GSSAPI configuration file |
d03f4262 | 60 | .Pq Pa $HOME/.ssh/config.gssapi |
61 | .It | |
d6862c36 | 62 | Kerberos configuration file |
d03f4262 | 63 | .Pq Pa $HOME/.ssh/config.krb |
64 | .It | |
d03f4262 | 65 | system-wide configuration file |
66 | .Pq Pa /etc/ssh/ssh_config | |
44a053a3 | 67 | .El |
884dc78b | 68 | .Pp |
69 | For each parameter, the first obtained value | |
70 | will be used. | |
dfddba3d | 71 | The configuration files contain sections separated by |
884dc78b | 72 | .Dq Host |
73 | specifications, and that section is only applied for hosts that | |
74 | match one of the patterns given in the specification. | |
75 | The matched host name is the one given on the command line. | |
76 | .Pp | |
77 | Since the first obtained value for each parameter is used, more | |
78 | host-specific declarations should be given near the beginning of the | |
79 | file, and general defaults at the end. | |
80 | .Pp | |
81 | The configuration file has the following format: | |
82 | .Pp | |
83 | Empty lines and lines starting with | |
84 | .Ql # | |
85 | are comments. | |
884dc78b | 86 | Otherwise a line is of the format |
87 | .Dq keyword arguments . | |
88 | Configuration options may be separated by whitespace or | |
89 | optional whitespace and exactly one | |
90 | .Ql = ; | |
91 | the latter format is useful to avoid the need to quote whitespace | |
92 | when specifying configuration options using the | |
93 | .Nm ssh , | |
30460aeb | 94 | .Nm scp , |
884dc78b | 95 | and |
96 | .Nm sftp | |
97 | .Fl o | |
98 | option. | |
30460aeb | 99 | Arguments may optionally be enclosed in double quotes |
100 | .Pq \&" | |
101 | in order to represent arguments containing spaces. | |
884dc78b | 102 | .Pp |
103 | The possible | |
104 | keywords and their meanings are as follows (note that | |
105 | keywords are case-insensitive and arguments are case-sensitive): | |
106 | .Bl -tag -width Ds | |
107 | .It Cm Host | |
108 | Restricts the following declarations (up to the next | |
109 | .Cm Host | |
110 | keyword) to be only for those hosts that match one of the patterns | |
111 | given after the keyword. | |
5262cbfb | 112 | If more than one pattern is provided, they should be separated by whitespace. |
884dc78b | 113 | A single |
30460aeb | 114 | .Ql * |
884dc78b | 115 | as a pattern can be used to provide global |
116 | defaults for all hosts. | |
117 | The host is the | |
118 | .Ar hostname | |
30460aeb | 119 | argument given on the command line (i.e. the name is not converted to |
884dc78b | 120 | a canonicalized host name before matching). |
30460aeb | 121 | .Pp |
122 | See | |
123 | .Sx PATTERNS | |
124 | for more information on patterns. | |
7cac2b65 | 125 | .It Cm AddressFamily |
126 | Specifies which address family to use when connecting. | |
127 | Valid arguments are | |
128 | .Dq any , | |
129 | .Dq inet | |
30460aeb | 130 | (use IPv4 only), or |
7cac2b65 | 131 | .Dq inet6 |
dfddba3d | 132 | (use IPv6 only). |
884dc78b | 133 | .It Cm BatchMode |
134 | If set to | |
135 | .Dq yes , | |
136 | passphrase/password querying will be disabled. | |
137 | This option is useful in scripts and other batch jobs where no user | |
138 | is present to supply the password. | |
139 | The argument must be | |
140 | .Dq yes | |
141 | or | |
142 | .Dq no . | |
143 | The default is | |
144 | .Dq no . | |
145 | .It Cm BindAddress | |
2ce0bfe4 | 146 | Use the specified address on the local machine as the source address of |
147 | the connection. | |
148 | Only useful on systems with more than one address. | |
884dc78b | 149 | Note that this option does not work if |
150 | .Cm UsePrivilegedPort | |
151 | is set to | |
152 | .Dq yes . | |
153 | .It Cm ChallengeResponseAuthentication | |
30460aeb | 154 | Specifies whether to use challenge-response authentication. |
884dc78b | 155 | The argument to this keyword must be |
156 | .Dq yes | |
157 | or | |
158 | .Dq no . | |
159 | The default is | |
160 | .Dq yes . | |
161 | .It Cm CheckHostIP | |
162 | If this flag is set to | |
163 | .Dq yes , | |
30460aeb | 164 | .Xr ssh 1 |
165 | will additionally check the host IP address in the | |
884dc78b | 166 | .Pa known_hosts |
167 | file. | |
168 | This allows ssh to detect if a host key changed due to DNS spoofing. | |
169 | If the option is set to | |
170 | .Dq no , | |
171 | the check will not be executed. | |
172 | The default is | |
173 | .Dq yes . | |
174 | .It Cm Cipher | |
175 | Specifies the cipher to use for encrypting the session | |
176 | in protocol version 1. | |
177 | Currently, | |
178 | .Dq blowfish , | |
179 | .Dq 3des , | |
180 | and | |
181 | .Dq des | |
182 | are supported. | |
183 | .Ar des | |
184 | is only supported in the | |
30460aeb | 185 | .Xr ssh 1 |
884dc78b | 186 | client for interoperability with legacy protocol 1 implementations |
187 | that do not support the | |
188 | .Ar 3des | |
bfe49944 | 189 | cipher. |
190 | Its use is strongly discouraged due to cryptographic weaknesses. | |
884dc78b | 191 | The default is |
192 | .Dq 3des . | |
193 | .It Cm Ciphers | |
194 | Specifies the ciphers allowed for protocol version 2 | |
195 | in order of preference. | |
196 | Multiple ciphers must be comma-separated. | |
7e82606e | 197 | The supported ciphers are |
198 | .Dq 3des-cbc , | |
199 | .Dq aes128-cbc , | |
200 | .Dq aes192-cbc , | |
201 | .Dq aes256-cbc , | |
202 | .Dq aes128-ctr , | |
203 | .Dq aes192-ctr , | |
204 | .Dq aes256-ctr , | |
2ce0bfe4 | 205 | .Dq arcfour128 , |
206 | .Dq arcfour256 , | |
7e82606e | 207 | .Dq arcfour , |
208 | .Dq blowfish-cbc , | |
209 | and | |
210 | .Dq cast128-cbc . | |
30460aeb | 211 | The default is: |
212 | .Bd -literal -offset 3n | |
5262cbfb | 213 | aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, |
214 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc, | |
215 | aes256-cbc,arcfour | |
884dc78b | 216 | .Ed |
217 | .It Cm ClearAllForwardings | |
30460aeb | 218 | Specifies that all local, remote, and dynamic port forwardings |
884dc78b | 219 | specified in the configuration files or on the command line be |
bfe49944 | 220 | cleared. |
221 | This option is primarily useful when used from the | |
30460aeb | 222 | .Xr ssh 1 |
884dc78b | 223 | command line to clear port forwardings set in |
224 | configuration files, and is automatically set by | |
225 | .Xr scp 1 | |
226 | and | |
227 | .Xr sftp 1 . | |
228 | The argument must be | |
229 | .Dq yes | |
230 | or | |
231 | .Dq no . | |
232 | The default is | |
233 | .Dq no . | |
234 | .It Cm Compression | |
235 | Specifies whether to use compression. | |
236 | The argument must be | |
237 | .Dq yes | |
238 | or | |
239 | .Dq no . | |
240 | The default is | |
241 | .Dq no . | |
242 | .It Cm CompressionLevel | |
243 | Specifies the compression level to use if compression is enabled. | |
244 | The argument must be an integer from 1 (fast) to 9 (slow, best). | |
245 | The default level is 6, which is good for most applications. | |
246 | The meaning of the values is the same as in | |
247 | .Xr gzip 1 . | |
248 | Note that this option applies to protocol version 1 only. | |
249 | .It Cm ConnectionAttempts | |
250 | Specifies the number of tries (one per second) to make before exiting. | |
251 | The argument must be an integer. | |
252 | This may be useful in scripts if the connection sometimes fails. | |
253 | The default is 1. | |
7cac2b65 | 254 | .It Cm ConnectTimeout |
30460aeb | 255 | Specifies the timeout (in seconds) used when connecting to the |
256 | SSH server, instead of using the default system TCP timeout. | |
7cac2b65 | 257 | This value is used only when the target is down or really unreachable, |
258 | not when it refuses the connection. | |
7e82606e | 259 | .It Cm ControlMaster |
260 | Enables the sharing of multiple sessions over a single network connection. | |
261 | When set to | |
30460aeb | 262 | .Dq yes , |
263 | .Xr ssh 1 | |
7e82606e | 264 | will listen for connections on a control socket specified using the |
265 | .Cm ControlPath | |
266 | argument. | |
267 | Additional sessions can connect to this socket using the same | |
268 | .Cm ControlPath | |
269 | with | |
270 | .Cm ControlMaster | |
271 | set to | |
272 | .Dq no | |
273 | (the default). | |
08822d99 | 274 | These sessions will try to reuse the master instance's network connection |
275 | rather than initiating new ones, but will fall back to connecting normally | |
276 | if the control socket does not exist, or is not listening. | |
277 | .Pp | |
7e82606e | 278 | Setting this to |
279 | .Dq ask | |
30460aeb | 280 | will cause ssh |
7e82606e | 281 | to listen for control connections, but require confirmation using the |
282 | .Ev SSH_ASKPASS | |
283 | program before they are accepted (see | |
284 | .Xr ssh-add 1 | |
285 | for details). | |
2ce0bfe4 | 286 | If the |
287 | .Cm ControlPath | |
30460aeb | 288 | cannot be opened, |
289 | ssh will continue without connecting to a master instance. | |
2ce0bfe4 | 290 | .Pp |
291 | X11 and | |
292 | .Xr ssh-agent 1 | |
293 | forwarding is supported over these multiplexed connections, however the | |
08822d99 | 294 | display and agent forwarded will be the one belonging to the master |
2ce0bfe4 | 295 | connection i.e. it is not possible to forward multiple displays or agents. |
296 | .Pp | |
297 | Two additional options allow for opportunistic multiplexing: try to use a | |
298 | master connection but fall back to creating a new one if one does not already | |
299 | exist. | |
300 | These options are: | |
301 | .Dq auto | |
302 | and | |
303 | .Dq autoask . | |
304 | The latter requires confirmation like the | |
305 | .Dq ask | |
306 | option. | |
7e82606e | 307 | .It Cm ControlPath |
2ce0bfe4 | 308 | Specify the path to the control socket used for connection sharing as described |
309 | in the | |
7e82606e | 310 | .Cm ControlMaster |
2ce0bfe4 | 311 | section above or the string |
312 | .Dq none | |
313 | to disable connection sharing. | |
314 | In the path, | |
30460aeb | 315 | .Ql %l |
316 | will be substituted by the local host name, | |
2ce0bfe4 | 317 | .Ql %h |
318 | will be substituted by the target host name, | |
319 | .Ql %p | |
30460aeb | 320 | the port, and |
2ce0bfe4 | 321 | .Ql %r |
322 | by the remote login username. | |
323 | It is recommended that any | |
324 | .Cm ControlPath | |
325 | used for opportunistic connection sharing include | |
30460aeb | 326 | at least %h, %p, and %r. |
2ce0bfe4 | 327 | This ensures that shared connections are uniquely identified. |
884dc78b | 328 | .It Cm DynamicForward |
08822d99 | 329 | Specifies that a TCP port on the local machine be forwarded |
884dc78b | 330 | over the secure channel, and the application |
331 | protocol is then used to determine where to connect to from the | |
bfe49944 | 332 | remote machine. |
08822d99 | 333 | .Pp |
334 | The argument must be | |
335 | .Sm off | |
336 | .Oo Ar bind_address : Oc Ar port . | |
337 | .Sm on | |
338 | IPv6 addresses can be specified by enclosing addresses in square brackets or | |
339 | by using an alternative syntax: | |
340 | .Oo Ar bind_address Ns / Oc Ns Ar port . | |
341 | By default, the local port is bound in accordance with the | |
342 | .Cm GatewayPorts | |
343 | setting. | |
344 | However, an explicit | |
345 | .Ar bind_address | |
346 | may be used to bind the connection to a specific address. | |
347 | The | |
348 | .Ar bind_address | |
349 | of | |
350 | .Dq localhost | |
351 | indicates that the listening port be bound for local use only, while an | |
352 | empty address or | |
353 | .Sq * | |
354 | indicates that the port should be available from all interfaces. | |
355 | .Pp | |
7cac2b65 | 356 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
30460aeb | 357 | .Xr ssh 1 |
7cac2b65 | 358 | will act as a SOCKS server. |
884dc78b | 359 | Multiple forwardings may be specified, and |
bfe49944 | 360 | additional forwardings can be given on the command line. |
361 | Only the superuser can forward privileged ports. | |
7cac2b65 | 362 | .It Cm EnableSSHKeysign |
363 | Setting this option to | |
364 | .Dq yes | |
365 | in the global client configuration file | |
366 | .Pa /etc/ssh/ssh_config | |
367 | enables the use of the helper program | |
368 | .Xr ssh-keysign 8 | |
369 | during | |
370 | .Cm HostbasedAuthentication . | |
371 | The argument must be | |
372 | .Dq yes | |
373 | or | |
374 | .Dq no . | |
375 | The default is | |
376 | .Dq no . | |
540d72c3 | 377 | This option should be placed in the non-hostspecific section. |
7cac2b65 | 378 | See |
379 | .Xr ssh-keysign 8 | |
380 | for more information. | |
884dc78b | 381 | .It Cm EscapeChar |
382 | Sets the escape character (default: | |
383 | .Ql ~ ) . | |
384 | The escape character can also | |
385 | be set on the command line. | |
386 | The argument should be a single character, | |
387 | .Ql ^ | |
388 | followed by a letter, or | |
389 | .Dq none | |
390 | to disable the escape | |
391 | character entirely (making the connection transparent for binary | |
392 | data). | |
30460aeb | 393 | .It Cm ExitOnForwardFailure |
394 | Specifies whether | |
395 | .Xr ssh 1 | |
396 | should terminate the connection if it cannot set up all requested | |
fa0f0f45 | 397 | dynamic, tunnel, local, and remote port forwardings. |
30460aeb | 398 | The argument must be |
399 | .Dq yes | |
400 | or | |
401 | .Dq no . | |
402 | The default is | |
403 | .Dq no . | |
884dc78b | 404 | .It Cm ForwardAgent |
405 | Specifies whether the connection to the authentication agent (if any) | |
406 | will be forwarded to the remote machine. | |
407 | The argument must be | |
408 | .Dq yes | |
409 | or | |
410 | .Dq no . | |
411 | The default is | |
412 | .Dq no . | |
d03f4262 | 413 | .Pp |
bfe49944 | 414 | Agent forwarding should be enabled with caution. |
415 | Users with the ability to bypass file permissions on the remote host | |
416 | (for the agent's Unix-domain socket) | |
417 | can access the local agent through the forwarded connection. | |
418 | An attacker cannot obtain key material from the agent, | |
d03f4262 | 419 | however they can perform operations on the keys that enable them to |
420 | authenticate using the identities loaded into the agent. | |
884dc78b | 421 | .It Cm ForwardX11 |
422 | Specifies whether X11 connections will be automatically redirected | |
423 | over the secure channel and | |
424 | .Ev DISPLAY | |
425 | set. | |
426 | The argument must be | |
427 | .Dq yes | |
428 | or | |
429 | .Dq no . | |
430 | The default is | |
431 | .Dq no . | |
d03f4262 | 432 | .Pp |
bfe49944 | 433 | X11 forwarding should be enabled with caution. |
434 | Users with the ability to bypass file permissions on the remote host | |
540d72c3 | 435 | (for the user's X11 authorization database) |
bfe49944 | 436 | can access the local X11 display through the forwarded connection. |
540d72c3 | 437 | An attacker may then be able to perform activities such as keystroke monitoring |
438 | if the | |
439 | .Cm ForwardX11Trusted | |
440 | option is also enabled. | |
441 | .It Cm ForwardX11Trusted | |
7e82606e | 442 | If this option is set to |
30460aeb | 443 | .Dq yes , |
444 | remote X11 clients will have full access to the original X11 display. | |
dfddba3d | 445 | .Pp |
540d72c3 | 446 | If this option is set to |
30460aeb | 447 | .Dq no , |
448 | remote X11 clients will be considered untrusted and prevented | |
540d72c3 | 449 | from stealing or tampering with data belonging to trusted X11 |
450 | clients. | |
dfddba3d | 451 | Furthermore, the |
452 | .Xr xauth 1 | |
453 | token used for the session will be set to expire after 20 minutes. | |
454 | Remote clients will be refused access after this time. | |
540d72c3 | 455 | .Pp |
456 | The default is | |
457 | .Dq no . | |
458 | .Pp | |
459 | See the X11 SECURITY extension specification for full details on | |
460 | the restrictions imposed on untrusted clients. | |
884dc78b | 461 | .It Cm GatewayPorts |
462 | Specifies whether remote hosts are allowed to connect to local | |
463 | forwarded ports. | |
464 | By default, | |
30460aeb | 465 | .Xr ssh 1 |
bfe49944 | 466 | binds local port forwardings to the loopback address. |
467 | This prevents other remote hosts from connecting to forwarded ports. | |
884dc78b | 468 | .Cm GatewayPorts |
30460aeb | 469 | can be used to specify that ssh |
884dc78b | 470 | should bind local port forwardings to the wildcard address, |
471 | thus allowing remote hosts to connect to forwarded ports. | |
472 | The argument must be | |
473 | .Dq yes | |
474 | or | |
475 | .Dq no . | |
476 | The default is | |
477 | .Dq no . | |
478 | .It Cm GlobalKnownHostsFile | |
479 | Specifies a file to use for the global | |
480 | host key database instead of | |
481 | .Pa /etc/ssh/ssh_known_hosts . | |
7cac2b65 | 482 | .It Cm GSSAPIAuthentication |
540d72c3 | 483 | Specifies whether user authentication based on GSSAPI is allowed. |
f713db99 | 484 | The default is |
44a053a3 | 485 | .Dq yes . |
85740ad2 | 486 | Note that this option applies to protocol version 2 only. |
7cac2b65 | 487 | .It Cm GSSAPIKeyExchange |
7a056ed1 | 488 | Specifies whether key exchange based on GSSAPI may be used. When using |
489 | GSSAPI key exchange the server need not have a host key. | |
490 | The default is | |
491 | .Dq yes . | |
85740ad2 | 492 | Note that this option applies to protocol version 2 only. |
7cac2b65 | 493 | .It Cm GSSAPIDelegateCredentials |
85740ad2 | 494 | Forward (delegate) credentials to the server. |
44a053a3 | 495 | The default is |
496 | .Dq yes . | |
85740ad2 | 497 | Note that this option applies to protocol version 2 only. |
fe4ad273 | 498 | .It Cm GSSAPITrustDns |
499 | Set to | |
f713db99 | 500 | .Dq yes |
501 | to indicate that the DNS is trusted to securely canonicalize | |
fe4ad273 | 502 | the name of the host being connected to. If |
9c0efabd | 503 | .Dq no , |
f713db99 | 504 | the hostname entered on the |
fe4ad273 | 505 | command line will be passed untouched to the GSSAPI library. |
506 | The default is | |
507 | .Dq yes . | |
f713db99 | 508 | This option only applies to protocol version 2 connections using GSSAPI. |
dfddba3d | 509 | .It Cm HashKnownHosts |
510 | Indicates that | |
30460aeb | 511 | .Xr ssh 1 |
dfddba3d | 512 | should hash host names and addresses when they are added to |
2ce0bfe4 | 513 | .Pa ~/.ssh/known_hosts . |
dfddba3d | 514 | These hashed names may be used normally by |
30460aeb | 515 | .Xr ssh 1 |
dfddba3d | 516 | and |
30460aeb | 517 | .Xr sshd 8 , |
dfddba3d | 518 | but they do not reveal identifying information should the file's contents |
519 | be disclosed. | |
520 | The default is | |
521 | .Dq no . | |
30460aeb | 522 | Note that existing names and addresses in known hosts files |
523 | will not be converted automatically, | |
524 | but may be manually hashed using | |
dfddba3d | 525 | .Xr ssh-keygen 1 . |
884dc78b | 526 | .It Cm HostbasedAuthentication |
527 | Specifies whether to try rhosts based authentication with public key | |
528 | authentication. | |
529 | The argument must be | |
530 | .Dq yes | |
531 | or | |
532 | .Dq no . | |
533 | The default is | |
534 | .Dq no . | |
535 | This option applies to protocol version 2 only and | |
536 | is similar to | |
537 | .Cm RhostsRSAAuthentication . | |
538 | .It Cm HostKeyAlgorithms | |
539 | Specifies the protocol version 2 host key algorithms | |
540 | that the client wants to use in order of preference. | |
541 | The default for this option is: | |
542 | .Dq ssh-rsa,ssh-dss . | |
543 | .It Cm HostKeyAlias | |
544 | Specifies an alias that should be used instead of the | |
545 | real host name when looking up or saving the host key | |
546 | in the host key database files. | |
30460aeb | 547 | This option is useful for tunneling SSH connections |
884dc78b | 548 | or for multiple servers running on a single host. |
549 | .It Cm HostName | |
550 | Specifies the real host name to log into. | |
551 | This can be used to specify nicknames or abbreviations for hosts. | |
30460aeb | 552 | The default is the name given on the command line. |
884dc78b | 553 | Numeric IP addresses are also permitted (both on the command line and in |
554 | .Cm HostName | |
555 | specifications). | |
12a403af | 556 | .It Cm IdentitiesOnly |
557 | Specifies that | |
30460aeb | 558 | .Xr ssh 1 |
12a403af | 559 | should only use the authentication identity files configured in the |
7e82606e | 560 | .Nm |
12a403af | 561 | files, |
30460aeb | 562 | even if |
563 | .Xr ssh-agent 1 | |
12a403af | 564 | offers more identities. |
565 | The argument to this keyword must be | |
566 | .Dq yes | |
567 | or | |
568 | .Dq no . | |
30460aeb | 569 | This option is intended for situations where ssh-agent |
12a403af | 570 | offers many different identities. |
571 | The default is | |
572 | .Dq no . | |
08822d99 | 573 | .It Cm IdentityFile |
574 | Specifies a file from which the user's RSA or DSA authentication identity | |
575 | is read. | |
576 | The default is | |
577 | .Pa ~/.ssh/identity | |
578 | for protocol version 1, and | |
579 | .Pa ~/.ssh/id_rsa | |
580 | and | |
581 | .Pa ~/.ssh/id_dsa | |
582 | for protocol version 2. | |
583 | Additionally, any identities represented by the authentication agent | |
584 | will be used for authentication. | |
30460aeb | 585 | .Pp |
08822d99 | 586 | The file name may use the tilde |
30460aeb | 587 | syntax to refer to a user's home directory or one of the following |
588 | escape characters: | |
589 | .Ql %d | |
590 | (local user's home directory), | |
591 | .Ql %u | |
592 | (local user name), | |
593 | .Ql %l | |
594 | (local host name), | |
595 | .Ql %h | |
596 | (remote host name) or | |
597 | .Ql %r | |
598 | (remote user name). | |
599 | .Pp | |
08822d99 | 600 | It is possible to have |
601 | multiple identity files specified in configuration files; all these | |
602 | identities will be tried in sequence. | |
e74dc197 | 603 | .It Cm KbdInteractiveAuthentication |
604 | Specifies whether to use keyboard-interactive authentication. | |
605 | The argument to this keyword must be | |
606 | .Dq yes | |
607 | or | |
608 | .Dq no . | |
609 | The default is | |
610 | .Dq yes . | |
dfddba3d | 611 | .It Cm KbdInteractiveDevices |
612 | Specifies the list of methods to use in keyboard-interactive authentication. | |
613 | Multiple method names must be comma-separated. | |
614 | The default is to use the server specified list. | |
30460aeb | 615 | The methods available vary depending on what the server supports. |
616 | For an OpenSSH server, | |
617 | it may be zero or more of: | |
618 | .Dq bsdauth , | |
619 | .Dq pam , | |
620 | and | |
621 | .Dq skey . | |
08822d99 | 622 | .It Cm LocalCommand |
623 | Specifies a command to execute on the local machine after successfully | |
624 | connecting to the server. | |
625 | The command string extends to the end of the line, and is executed with | |
e74dc197 | 626 | the user's shell. |
5156b1a1 | 627 | The following escape character substitutions will be performed: |
628 | .Ql %d | |
629 | (local user's home directory), | |
630 | .Ql %h | |
631 | (remote host name), | |
632 | .Ql %l | |
633 | (local host name), | |
634 | .Ql %n | |
635 | (host name as provided on the command line), | |
636 | .Ql %p | |
637 | (remote port), | |
638 | .Ql %r | |
639 | (remote user name) or | |
640 | .Ql %u | |
641 | (local user name). | |
08822d99 | 642 | This directive is ignored unless |
643 | .Cm PermitLocalCommand | |
644 | has been enabled. | |
884dc78b | 645 | .It Cm LocalForward |
08822d99 | 646 | Specifies that a TCP port on the local machine be forwarded over |
884dc78b | 647 | the secure channel to the specified host and port from the remote machine. |
8b32eddc | 648 | The first argument must be |
dfddba3d | 649 | .Sm off |
8b32eddc | 650 | .Oo Ar bind_address : Oc Ar port |
dfddba3d | 651 | .Sm on |
8b32eddc | 652 | and the second argument must be |
653 | .Ar host : Ns Ar hostport . | |
dfddba3d | 654 | IPv6 addresses can be specified by enclosing addresses in square brackets or |
655 | by using an alternative syntax: | |
8b32eddc | 656 | .Oo Ar bind_address Ns / Oc Ns Ar port |
657 | and | |
658 | .Ar host Ns / Ns Ar hostport . | |
dfddba3d | 659 | Multiple forwardings may be specified, and additional forwardings can be |
660 | given on the command line. | |
884dc78b | 661 | Only the superuser can forward privileged ports. |
dfddba3d | 662 | By default, the local port is bound in accordance with the |
663 | .Cm GatewayPorts | |
664 | setting. | |
665 | However, an explicit | |
666 | .Ar bind_address | |
667 | may be used to bind the connection to a specific address. | |
668 | The | |
669 | .Ar bind_address | |
670 | of | |
671 | .Dq localhost | |
672 | indicates that the listening port be bound for local use only, while an | |
673 | empty address or | |
674 | .Sq * | |
675 | indicates that the port should be available from all interfaces. | |
884dc78b | 676 | .It Cm LogLevel |
677 | Gives the verbosity level that is used when logging messages from | |
30460aeb | 678 | .Xr ssh 1 . |
884dc78b | 679 | The possible values are: |
30460aeb | 680 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
bfe49944 | 681 | The default is INFO. |
682 | DEBUG and DEBUG1 are equivalent. | |
683 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. | |
884dc78b | 684 | .It Cm MACs |
685 | Specifies the MAC (message authentication code) algorithms | |
686 | in order of preference. | |
687 | The MAC algorithm is used in protocol version 2 | |
688 | for data integrity protection. | |
689 | Multiple algorithms must be comma-separated. | |
30460aeb | 690 | The default is: |
fa0f0f45 | 691 | .Bd -literal -offset indent |
692 | hmac-md5,hmac-sha1,umac-64@openssh.com, | |
693 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 | |
694 | .Ed | |
884dc78b | 695 | .It Cm NoHostAuthenticationForLocalhost |
696 | This option can be used if the home directory is shared across machines. | |
697 | In this case localhost will refer to a different machine on each of | |
698 | the machines and the user will get many warnings about changed host keys. | |
699 | However, this option disables host authentication for localhost. | |
700 | The argument to this keyword must be | |
701 | .Dq yes | |
702 | or | |
703 | .Dq no . | |
704 | The default is to check the host key for localhost. | |
705 | .It Cm NumberOfPasswordPrompts | |
706 | Specifies the number of password prompts before giving up. | |
707 | The argument to this keyword must be an integer. | |
30460aeb | 708 | The default is 3. |
884dc78b | 709 | .It Cm PasswordAuthentication |
710 | Specifies whether to use password authentication. | |
711 | The argument to this keyword must be | |
712 | .Dq yes | |
713 | or | |
714 | .Dq no . | |
715 | The default is | |
716 | .Dq yes . | |
08822d99 | 717 | .It Cm PermitLocalCommand |
718 | Allow local command execution via the | |
719 | .Ic LocalCommand | |
720 | option or using the | |
721 | .Ic !\& Ns Ar command | |
722 | escape sequence in | |
723 | .Xr ssh 1 . | |
724 | The argument must be | |
725 | .Dq yes | |
726 | or | |
727 | .Dq no . | |
728 | The default is | |
729 | .Dq no . | |
884dc78b | 730 | .It Cm Port |
731 | Specifies the port number to connect on the remote host. | |
30460aeb | 732 | The default is 22. |
884dc78b | 733 | .It Cm PreferredAuthentications |
734 | Specifies the order in which the client should try protocol 2 | |
7cac2b65 | 735 | authentication methods. |
8b32eddc | 736 | This allows a client to prefer one method (e.g.\& |
884dc78b | 737 | .Cm keyboard-interactive ) |
8b32eddc | 738 | over another method (e.g.\& |
884dc78b | 739 | .Cm password ) |
740 | The default for this option is: | |
30460aeb | 741 | .Do gssapi-keyex , |
742 | external-keyx, | |
743 | gssapi-with-mic, | |
744 | hostbased, | |
745 | publickey, | |
746 | keyboard-interactive, | |
747 | password | |
748 | .Dc . | |
884dc78b | 749 | .It Cm Protocol |
750 | Specifies the protocol versions | |
30460aeb | 751 | .Xr ssh 1 |
884dc78b | 752 | should support in order of preference. |
753 | The possible values are | |
30460aeb | 754 | .Sq 1 |
884dc78b | 755 | and |
30460aeb | 756 | .Sq 2 . |
884dc78b | 757 | Multiple versions must be comma-separated. |
758 | The default is | |
759 | .Dq 2,1 . | |
30460aeb | 760 | This means that ssh |
884dc78b | 761 | tries version 2 and falls back to version 1 |
762 | if version 2 is not available. | |
763 | .It Cm ProxyCommand | |
764 | Specifies the command to use to connect to the server. | |
765 | The command | |
766 | string extends to the end of the line, and is executed with | |
e74dc197 | 767 | the user's shell. |
884dc78b | 768 | In the command string, |
769 | .Ql %h | |
770 | will be substituted by the host name to | |
771 | connect and | |
772 | .Ql %p | |
773 | by the port. | |
774 | The command can be basically anything, | |
775 | and should read from its standard input and write to its standard output. | |
776 | It should eventually connect an | |
777 | .Xr sshd 8 | |
778 | server running on some machine, or execute | |
779 | .Ic sshd -i | |
780 | somewhere. | |
781 | Host key management will be done using the | |
782 | HostName of the host being connected (defaulting to the name typed by | |
783 | the user). | |
bfe49944 | 784 | Setting the command to |
785 | .Dq none | |
786 | disables this option entirely. | |
884dc78b | 787 | Note that |
788 | .Cm CheckHostIP | |
789 | is not available for connects with a proxy command. | |
790 | .Pp | |
2ce0bfe4 | 791 | This directive is useful in conjunction with |
792 | .Xr nc 1 | |
793 | and its proxy support. | |
794 | For example, the following directive would connect via an HTTP proxy at | |
795 | 192.0.2.0: | |
796 | .Bd -literal -offset 3n | |
797 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p | |
798 | .Ed | |
884dc78b | 799 | .It Cm PubkeyAuthentication |
800 | Specifies whether to try public key authentication. | |
801 | The argument to this keyword must be | |
802 | .Dq yes | |
803 | or | |
804 | .Dq no . | |
805 | The default is | |
806 | .Dq yes . | |
807 | This option applies to protocol version 2 only. | |
08822d99 | 808 | .It Cm RekeyLimit |
809 | Specifies the maximum amount of data that may be transmitted before the | |
810 | session key is renegotiated. | |
811 | The argument is the number of bytes, with an optional suffix of | |
812 | .Sq K , | |
813 | .Sq M , | |
814 | or | |
815 | .Sq G | |
816 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. | |
817 | The default is between | |
30460aeb | 818 | .Sq 1G |
08822d99 | 819 | and |
30460aeb | 820 | .Sq 4G , |
08822d99 | 821 | depending on the cipher. |
822 | This option applies to protocol version 2 only. | |
884dc78b | 823 | .It Cm RemoteForward |
08822d99 | 824 | Specifies that a TCP port on the remote machine be forwarded over |
884dc78b | 825 | the secure channel to the specified host and port from the local machine. |
8b32eddc | 826 | The first argument must be |
dfddba3d | 827 | .Sm off |
8b32eddc | 828 | .Oo Ar bind_address : Oc Ar port |
dfddba3d | 829 | .Sm on |
8b32eddc | 830 | and the second argument must be |
831 | .Ar host : Ns Ar hostport . | |
832 | IPv6 addresses can be specified by enclosing addresses in square brackets | |
833 | or by using an alternative syntax: | |
834 | .Oo Ar bind_address Ns / Oc Ns Ar port | |
835 | and | |
836 | .Ar host Ns / Ns Ar hostport . | |
884dc78b | 837 | Multiple forwardings may be specified, and additional |
838 | forwardings can be given on the command line. | |
5262cbfb | 839 | Privileged ports can be forwarded only when |
840 | logging in as root on the remote machine. | |
841 | .Pp | |
842 | If the | |
843 | .Ar port | |
844 | argument is | |
845 | .Ql 0 , | |
846 | the listen port will be dynamically allocated on the server and reported | |
847 | to the client at run time. | |
dfddba3d | 848 | .Pp |
849 | If the | |
850 | .Ar bind_address | |
851 | is not specified, the default is to only bind to loopback addresses. | |
852 | If the | |
853 | .Ar bind_address | |
854 | is | |
855 | .Ql * | |
856 | or an empty string, then the forwarding is requested to listen on all | |
857 | interfaces. | |
858 | Specifying a remote | |
859 | .Ar bind_address | |
860 | will only succeed if the server's | |
861 | .Cm GatewayPorts | |
862 | option is enabled (see | |
863 | .Xr sshd_config 5 ) . | |
884dc78b | 864 | .It Cm RhostsRSAAuthentication |
865 | Specifies whether to try rhosts based authentication with RSA host | |
866 | authentication. | |
867 | The argument must be | |
868 | .Dq yes | |
869 | or | |
870 | .Dq no . | |
871 | The default is | |
872 | .Dq no . | |
873 | This option applies to protocol version 1 only and requires | |
30460aeb | 874 | .Xr ssh 1 |
884dc78b | 875 | to be setuid root. |
876 | .It Cm RSAAuthentication | |
877 | Specifies whether to try RSA authentication. | |
878 | The argument to this keyword must be | |
879 | .Dq yes | |
880 | or | |
881 | .Dq no . | |
882 | RSA authentication will only be | |
883 | attempted if the identity file exists, or an authentication agent is | |
884 | running. | |
885 | The default is | |
886 | .Dq yes . | |
887 | Note that this option applies to protocol version 1 only. | |
7e82606e | 888 | .It Cm SendEnv |
889 | Specifies what variables from the local | |
890 | .Xr environ 7 | |
891 | should be sent to the server. | |
30460aeb | 892 | Note that environment passing is only supported for protocol 2. |
893 | The server must also support it, and the server must be configured to | |
7e82606e | 894 | accept these environment variables. |
895 | Refer to | |
896 | .Cm AcceptEnv | |
897 | in | |
898 | .Xr sshd_config 5 | |
899 | for how to configure the server. | |
30460aeb | 900 | Variables are specified by name, which may contain wildcard characters. |
7e82606e | 901 | Multiple environment variables may be separated by whitespace or spread |
902 | across multiple | |
903 | .Cm SendEnv | |
904 | directives. | |
905 | The default is not to send any environment variables. | |
30460aeb | 906 | .Pp |
907 | See | |
908 | .Sx PATTERNS | |
909 | for more information on patterns. | |
540d72c3 | 910 | .It Cm ServerAliveCountMax |
08822d99 | 911 | Sets the number of server alive messages (see below) which may be |
540d72c3 | 912 | sent without |
30460aeb | 913 | .Xr ssh 1 |
540d72c3 | 914 | receiving any messages back from the server. |
915 | If this threshold is reached while server alive messages are being sent, | |
30460aeb | 916 | ssh will disconnect from the server, terminating the session. |
540d72c3 | 917 | It is important to note that the use of server alive messages is very |
918 | different from | |
919 | .Cm TCPKeepAlive | |
920 | (below). | |
921 | The server alive messages are sent through the encrypted channel | |
922 | and therefore will not be spoofable. | |
923 | The TCP keepalive option enabled by | |
924 | .Cm TCPKeepAlive | |
925 | is spoofable. | |
926 | The server alive mechanism is valuable when the client or | |
927 | server depend on knowing when a connection has become inactive. | |
928 | .Pp | |
929 | The default value is 3. | |
930 | If, for example, | |
931 | .Cm ServerAliveInterval | |
30460aeb | 932 | (see below) is set to 15 and |
540d72c3 | 933 | .Cm ServerAliveCountMax |
30460aeb | 934 | is left at the default, if the server becomes unresponsive, |
935 | ssh will disconnect after approximately 45 seconds. | |
936 | This option applies to protocol version 2 only. | |
08822d99 | 937 | .It Cm ServerAliveInterval |
938 | Sets a timeout interval in seconds after which if no data has been received | |
939 | from the server, | |
30460aeb | 940 | .Xr ssh 1 |
08822d99 | 941 | will send a message through the encrypted |
942 | channel to request a response from the server. | |
943 | The default | |
944 | is 0, indicating that these messages will not be sent to the server. | |
945 | This option applies to protocol version 2 only. | |
884dc78b | 946 | .It Cm SmartcardDevice |
7cac2b65 | 947 | Specifies which smartcard device to use. |
948 | The argument to this keyword is the device | |
30460aeb | 949 | .Xr ssh 1 |
884dc78b | 950 | should use to communicate with a smartcard used for storing the user's |
7cac2b65 | 951 | private RSA key. |
952 | By default, no device is specified and smartcard support is not activated. | |
884dc78b | 953 | .It Cm StrictHostKeyChecking |
954 | If this flag is set to | |
955 | .Dq yes , | |
30460aeb | 956 | .Xr ssh 1 |
884dc78b | 957 | will never automatically add host keys to the |
2ce0bfe4 | 958 | .Pa ~/.ssh/known_hosts |
884dc78b | 959 | file, and refuses to connect to hosts whose host key has changed. |
960 | This provides maximum protection against trojan horse attacks, | |
30460aeb | 961 | though it can be annoying when the |
884dc78b | 962 | .Pa /etc/ssh/ssh_known_hosts |
30460aeb | 963 | file is poorly maintained or when connections to new hosts are |
884dc78b | 964 | frequently made. |
965 | This option forces the user to manually | |
966 | add all new hosts. | |
967 | If this flag is set to | |
968 | .Dq no , | |
30460aeb | 969 | ssh will automatically add new host keys to the |
884dc78b | 970 | user known hosts files. |
971 | If this flag is set to | |
972 | .Dq ask , | |
973 | new host keys | |
974 | will be added to the user known host files only after the user | |
975 | has confirmed that is what they really want to do, and | |
30460aeb | 976 | ssh will refuse to connect to hosts whose host key has changed. |
884dc78b | 977 | The host keys of |
978 | known hosts will be verified automatically in all cases. | |
979 | The argument must be | |
980 | .Dq yes , | |
30460aeb | 981 | .Dq no , |
884dc78b | 982 | or |
983 | .Dq ask . | |
984 | The default is | |
985 | .Dq ask . | |
540d72c3 | 986 | .It Cm TCPKeepAlive |
987 | Specifies whether the system should send TCP keepalive messages to the | |
988 | other side. | |
989 | If they are sent, death of the connection or crash of one | |
990 | of the machines will be properly noticed. | |
991 | However, this means that | |
992 | connections will die if the route is down temporarily, and some people | |
993 | find it annoying. | |
994 | .Pp | |
995 | The default is | |
996 | .Dq yes | |
997 | (to send TCP keepalive messages), and the client will notice | |
998 | if the network goes down or the remote host dies. | |
999 | This is important in scripts, and many users want it too. | |
1000 | .Pp | |
1001 | To disable TCP keepalive messages, the value should be set to | |
1002 | .Dq no . | |
08822d99 | 1003 | .It Cm Tunnel |
30460aeb | 1004 | Request |
08822d99 | 1005 | .Xr tun 4 |
1006 | device forwarding between the client and the server. | |
08822d99 | 1007 | The argument must be |
1008 | .Dq yes , | |
30460aeb | 1009 | .Dq point-to-point |
1010 | (layer 3), | |
08822d99 | 1011 | .Dq ethernet |
30460aeb | 1012 | (layer 2), |
08822d99 | 1013 | or |
1014 | .Dq no . | |
30460aeb | 1015 | Specifying |
1016 | .Dq yes | |
1017 | requests the default tunnel mode, which is | |
1018 | .Dq point-to-point . | |
08822d99 | 1019 | The default is |
1020 | .Dq no . | |
1021 | .It Cm TunnelDevice | |
30460aeb | 1022 | Specifies the |
08822d99 | 1023 | .Xr tun 4 |
30460aeb | 1024 | devices to open on the client |
1025 | .Pq Ar local_tun | |
1026 | and the server | |
1027 | .Pq Ar remote_tun . | |
1028 | .Pp | |
1029 | The argument must be | |
1030 | .Sm off | |
1031 | .Ar local_tun Op : Ar remote_tun . | |
1032 | .Sm on | |
1033 | The devices may be specified by numerical ID or the keyword | |
1034 | .Dq any , | |
1035 | which uses the next available tunnel device. | |
1036 | If | |
1037 | .Ar remote_tun | |
1038 | is not specified, it defaults to | |
1039 | .Dq any . | |
1040 | The default is | |
1041 | .Dq any:any . | |
884dc78b | 1042 | .It Cm UsePrivilegedPort |
1043 | Specifies whether to use a privileged port for outgoing connections. | |
1044 | The argument must be | |
1045 | .Dq yes | |
1046 | or | |
1047 | .Dq no . | |
1048 | The default is | |
1049 | .Dq no . | |
d03f4262 | 1050 | If set to |
30460aeb | 1051 | .Dq yes , |
1052 | .Xr ssh 1 | |
d03f4262 | 1053 | must be setuid root. |
884dc78b | 1054 | Note that this option must be set to |
1055 | .Dq yes | |
7cac2b65 | 1056 | for |
884dc78b | 1057 | .Cm RhostsRSAAuthentication |
7cac2b65 | 1058 | with older servers. |
884dc78b | 1059 | .It Cm User |
1060 | Specifies the user to log in as. | |
1061 | This can be useful when a different user name is used on different machines. | |
1062 | This saves the trouble of | |
1063 | having to remember to give the user name on the command line. | |
1064 | .It Cm UserKnownHostsFile | |
1065 | Specifies a file to use for the user | |
1066 | host key database instead of | |
2ce0bfe4 | 1067 | .Pa ~/.ssh/known_hosts . |
7cac2b65 | 1068 | .It Cm VerifyHostKeyDNS |
1069 | Specifies whether to verify the remote key using DNS and SSHFP resource | |
1070 | records. | |
540d72c3 | 1071 | If this option is set to |
1072 | .Dq yes , | |
1073 | the client will implicitly trust keys that match a secure fingerprint | |
1074 | from DNS. | |
1075 | Insecure fingerprints will be handled as if this option was set to | |
1076 | .Dq ask . | |
1077 | If this option is set to | |
1078 | .Dq ask , | |
1079 | information on fingerprint match will be displayed, but the user will still | |
1080 | need to confirm new host keys according to the | |
1081 | .Cm StrictHostKeyChecking | |
1082 | option. | |
1083 | The argument must be | |
1084 | .Dq yes , | |
30460aeb | 1085 | .Dq no , |
540d72c3 | 1086 | or |
1087 | .Dq ask . | |
7cac2b65 | 1088 | The default is |
1089 | .Dq no . | |
1090 | Note that this option applies to protocol version 2 only. | |
30460aeb | 1091 | .Pp |
1092 | See also | |
1093 | .Sx VERIFYING HOST KEYS | |
1094 | in | |
1095 | .Xr ssh 1 . | |
5156b1a1 | 1096 | .It Cm VisualHostKey |
1097 | If this flag is set to | |
1098 | .Dq yes , | |
1099 | an ASCII art representation of the remote host key fingerprint is | |
5262cbfb | 1100 | printed in addition to the hex fingerprint string at login and |
1101 | for unknown host keys. | |
5156b1a1 | 1102 | If this flag is set to |
1103 | .Dq no , | |
5262cbfb | 1104 | no fingerprint strings are printed at login and |
1105 | only the hex fingerprint string will be printed for unknown host keys. | |
5156b1a1 | 1106 | The default is |
1107 | .Dq no . | |
884dc78b | 1108 | .It Cm XAuthLocation |
d03f4262 | 1109 | Specifies the full pathname of the |
884dc78b | 1110 | .Xr xauth 1 |
1111 | program. | |
1112 | The default is | |
1113 | .Pa /usr/X11R6/bin/xauth . | |
1114 | .El | |
30460aeb | 1115 | .Sh PATTERNS |
1116 | A | |
1117 | .Em pattern | |
1118 | consists of zero or more non-whitespace characters, | |
1119 | .Sq * | |
1120 | (a wildcard that matches zero or more characters), | |
1121 | or | |
1122 | .Sq ?\& | |
1123 | (a wildcard that matches exactly one character). | |
1124 | For example, to specify a set of declarations for any host in the | |
1125 | .Dq .co.uk | |
1126 | set of domains, | |
1127 | the following pattern could be used: | |
1128 | .Pp | |
1129 | .Dl Host *.co.uk | |
1130 | .Pp | |
1131 | The following pattern | |
1132 | would match any host in the 192.168.0.[0-9] network range: | |
1133 | .Pp | |
1134 | .Dl Host 192.168.0.? | |
1135 | .Pp | |
1136 | A | |
1137 | .Em pattern-list | |
1138 | is a comma-separated list of patterns. | |
1139 | Patterns within pattern-lists may be negated | |
1140 | by preceding them with an exclamation mark | |
1141 | .Pq Sq !\& . | |
1142 | For example, | |
1143 | to allow a key to be used from anywhere within an organisation | |
1144 | except from the | |
1145 | .Dq dialup | |
1146 | pool, | |
1147 | the following entry (in authorized_keys) could be used: | |
1148 | .Pp | |
1149 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" | |
884dc78b | 1150 | .Sh FILES |
1151 | .Bl -tag -width Ds | |
2ce0bfe4 | 1152 | .It Pa ~/.ssh/config |
884dc78b | 1153 | This is the per-user configuration file. |
1154 | The format of this file is described above. | |
30460aeb | 1155 | This file is used by the SSH client. |
7e82606e | 1156 | Because of the potential for abuse, this file must have strict permissions: |
1157 | read/write for the user, and not accessible by others. | |
884dc78b | 1158 | .It Pa /etc/ssh/ssh_config |
1159 | Systemwide configuration file. | |
1160 | This file provides defaults for those | |
1161 | values that are not specified in the user's configuration file, and | |
1162 | for those users who do not have a configuration file. | |
1163 | This file must be world-readable. | |
1164 | .El | |
7cac2b65 | 1165 | .Sh SEE ALSO |
1166 | .Xr ssh 1 | |
884dc78b | 1167 | .Sh AUTHORS |
1168 | OpenSSH is a derivative of the original and free | |
1169 | ssh 1.2.12 release by Tatu Ylonen. | |
1170 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
1171 | Theo de Raadt and Dug Song | |
1172 | removed many bugs, re-added newer features and | |
1173 | created OpenSSH. | |
1174 | Markus Friedl contributed the support for SSH | |
1175 | protocol versions 1.5 and 2.0. |