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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 | .\" | ||
37 | .\" $OpenBSD: ssh_config.5,v 1.1 2002/06/20 19:56:07 stevesk Exp $ | ||
38 | .Dd September 25, 1999 | ||
39 | .Dt SSH_CONFIG 5 | ||
40 | .Os | ||
41 | .Sh NAME | ||
42 | .Nm ssh_config | ||
43 | .Nd OpenSSH SSH client configuration files | ||
44 | .Sh SYNOPSIS | ||
45 | .Bl -tag -width Ds -compact | ||
46 | .It Pa $HOME/.ssh/config | ||
47 | .It Pa /etc/ssh/ssh_config | ||
48 | .El | ||
49 | .Sh DESCRIPTION | ||
50 | .Nm ssh | ||
51 | obtains configuration data from the following sources in | ||
52 | the following order: | ||
53 | command line options, user's configuration file | ||
54 | .Pq Pa $HOME/.ssh/config , | ||
55 | and system-wide configuration file | ||
56 | .Pq Pa /etc/ssh/ssh_config . | ||
57 | .Pp | ||
58 | For each parameter, the first obtained value | ||
59 | will be used. | ||
60 | The configuration files contain sections bracketed by | ||
61 | .Dq Host | ||
62 | specifications, and that section is only applied for hosts that | ||
63 | match one of the patterns given in the specification. | ||
64 | The matched host name is the one given on the command line. | ||
65 | .Pp | ||
66 | Since the first obtained value for each parameter is used, more | ||
67 | host-specific declarations should be given near the beginning of the | ||
68 | file, and general defaults at the end. | ||
69 | .Pp | ||
70 | The configuration file has the following format: | ||
71 | .Pp | ||
72 | Empty lines and lines starting with | ||
73 | .Ql # | ||
74 | are comments. | ||
75 | .Pp | ||
76 | Otherwise a line is of the format | ||
77 | .Dq keyword arguments . | ||
78 | Configuration options may be separated by whitespace or | ||
79 | optional whitespace and exactly one | ||
80 | .Ql = ; | ||
81 | the latter format is useful to avoid the need to quote whitespace | ||
82 | when specifying configuration options using the | ||
83 | .Nm ssh , | ||
84 | .Nm scp | ||
85 | and | ||
86 | .Nm sftp | ||
87 | .Fl o | ||
88 | option. | ||
89 | .Pp | ||
90 | The possible | ||
91 | keywords and their meanings are as follows (note that | ||
92 | keywords are case-insensitive and arguments are case-sensitive): | ||
93 | .Bl -tag -width Ds | ||
94 | .It Cm Host | ||
95 | Restricts the following declarations (up to the next | ||
96 | .Cm Host | ||
97 | keyword) to be only for those hosts that match one of the patterns | ||
98 | given after the keyword. | ||
99 | .Ql \&* | ||
100 | and | ||
101 | .Ql ? | ||
102 | can be used as wildcards in the | ||
103 | patterns. | ||
104 | A single | ||
105 | .Ql \&* | ||
106 | as a pattern can be used to provide global | ||
107 | defaults for all hosts. | ||
108 | The host is the | ||
109 | .Ar hostname | ||
110 | argument given on the command line (i.e., the name is not converted to | ||
111 | a canonicalized host name before matching). | ||
112 | .It Cm AFSTokenPassing | ||
113 | Specifies whether to pass AFS tokens to remote host. | ||
114 | The argument to this keyword must be | ||
115 | .Dq yes | ||
116 | or | ||
117 | .Dq no . | ||
118 | This option applies to protocol version 1 only. | ||
119 | .It Cm BatchMode | ||
120 | If set to | ||
121 | .Dq yes , | ||
122 | passphrase/password querying will be disabled. | ||
123 | This option is useful in scripts and other batch jobs where no user | ||
124 | is present to supply the password. | ||
125 | The argument must be | ||
126 | .Dq yes | ||
127 | or | ||
128 | .Dq no . | ||
129 | The default is | ||
130 | .Dq no . | ||
131 | .It Cm BindAddress | ||
132 | Specify the interface to transmit from on machines with multiple | ||
133 | interfaces or aliased addresses. | ||
134 | Note that this option does not work if | ||
135 | .Cm UsePrivilegedPort | ||
136 | is set to | ||
137 | .Dq yes . | ||
138 | .It Cm ChallengeResponseAuthentication | ||
139 | Specifies whether to use challenge response authentication. | ||
140 | The argument to this keyword must be | ||
141 | .Dq yes | ||
142 | or | ||
143 | .Dq no . | ||
144 | The default is | ||
145 | .Dq yes . | ||
146 | .It Cm CheckHostIP | ||
147 | If this flag is set to | ||
148 | .Dq yes , | ||
149 | ssh will additionally check the host IP address in the | ||
150 | .Pa known_hosts | ||
151 | file. | ||
152 | This allows ssh to detect if a host key changed due to DNS spoofing. | ||
153 | If the option is set to | ||
154 | .Dq no , | ||
155 | the check will not be executed. | ||
156 | The default is | ||
157 | .Dq yes . | ||
158 | .It Cm Cipher | ||
159 | Specifies the cipher to use for encrypting the session | ||
160 | in protocol version 1. | ||
161 | Currently, | ||
162 | .Dq blowfish , | ||
163 | .Dq 3des , | ||
164 | and | ||
165 | .Dq des | ||
166 | are supported. | ||
167 | .Ar des | ||
168 | is only supported in the | ||
169 | .Nm ssh | ||
170 | client for interoperability with legacy protocol 1 implementations | ||
171 | that do not support the | ||
172 | .Ar 3des | ||
173 | cipher. Its use is strongly discouraged due to cryptographic | ||
174 | weaknesses. | ||
175 | The default is | ||
176 | .Dq 3des . | ||
177 | .It Cm Ciphers | ||
178 | Specifies the ciphers allowed for protocol version 2 | ||
179 | in order of preference. | ||
180 | Multiple ciphers must be comma-separated. | ||
181 | The default is | ||
182 | .Pp | ||
183 | .Bd -literal | ||
184 | ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour, | ||
185 | aes192-cbc,aes256-cbc'' | ||
186 | .Ed | ||
187 | .It Cm ClearAllForwardings | ||
188 | Specifies that all local, remote and dynamic port forwardings | ||
189 | specified in the configuration files or on the command line be | ||
190 | cleared. This option is primarily useful when used from the | ||
191 | .Nm ssh | ||
192 | command line to clear port forwardings set in | ||
193 | configuration files, and is automatically set by | ||
194 | .Xr scp 1 | ||
195 | and | ||
196 | .Xr sftp 1 . | ||
197 | The argument must be | ||
198 | .Dq yes | ||
199 | or | ||
200 | .Dq no . | ||
201 | The default is | ||
202 | .Dq no . | ||
203 | .It Cm Compression | ||
204 | Specifies whether to use compression. | ||
205 | The argument must be | ||
206 | .Dq yes | ||
207 | or | ||
208 | .Dq no . | ||
209 | The default is | ||
210 | .Dq no . | ||
211 | .It Cm CompressionLevel | ||
212 | Specifies the compression level to use if compression is enabled. | ||
213 | The argument must be an integer from 1 (fast) to 9 (slow, best). | ||
214 | The default level is 6, which is good for most applications. | ||
215 | The meaning of the values is the same as in | ||
216 | .Xr gzip 1 . | ||
217 | Note that this option applies to protocol version 1 only. | ||
218 | .It Cm ConnectionAttempts | ||
219 | Specifies the number of tries (one per second) to make before exiting. | ||
220 | The argument must be an integer. | ||
221 | This may be useful in scripts if the connection sometimes fails. | ||
222 | The default is 1. | ||
223 | .It Cm DynamicForward | ||
224 | Specifies that a TCP/IP port on the local machine be forwarded | ||
225 | over the secure channel, and the application | ||
226 | protocol is then used to determine where to connect to from the | ||
227 | remote machine. The argument must be a port number. | ||
228 | Currently the SOCKS4 protocol is supported, and | ||
229 | .Nm ssh | ||
230 | will act as a SOCKS4 server. | ||
231 | Multiple forwardings may be specified, and | ||
232 | additional forwardings can be given on the command line. Only | ||
233 | the superuser can forward privileged ports. | ||
234 | .It Cm EscapeChar | ||
235 | Sets the escape character (default: | ||
236 | .Ql ~ ) . | ||
237 | The escape character can also | ||
238 | be set on the command line. | ||
239 | The argument should be a single character, | ||
240 | .Ql ^ | ||
241 | followed by a letter, or | ||
242 | .Dq none | ||
243 | to disable the escape | ||
244 | character entirely (making the connection transparent for binary | ||
245 | data). | ||
246 | .It Cm ForwardAgent | ||
247 | Specifies whether the connection to the authentication agent (if any) | ||
248 | will be forwarded to the remote machine. | ||
249 | The argument must be | ||
250 | .Dq yes | ||
251 | or | ||
252 | .Dq no . | ||
253 | The default is | ||
254 | .Dq no . | ||
255 | .It Cm ForwardX11 | ||
256 | Specifies whether X11 connections will be automatically redirected | ||
257 | over the secure channel and | ||
258 | .Ev DISPLAY | ||
259 | set. | ||
260 | The argument must be | ||
261 | .Dq yes | ||
262 | or | ||
263 | .Dq no . | ||
264 | The default is | ||
265 | .Dq no . | ||
266 | .It Cm GatewayPorts | ||
267 | Specifies whether remote hosts are allowed to connect to local | ||
268 | forwarded ports. | ||
269 | By default, | ||
270 | .Nm ssh | ||
271 | binds local port forwardings to the loopback address. This | ||
272 | prevents other remote hosts from connecting to forwarded ports. | ||
273 | .Cm GatewayPorts | ||
274 | can be used to specify that | ||
275 | .Nm ssh | ||
276 | should bind local port forwardings to the wildcard address, | ||
277 | thus allowing remote hosts to connect to forwarded ports. | ||
278 | The argument must be | ||
279 | .Dq yes | ||
280 | or | ||
281 | .Dq no . | ||
282 | The default is | ||
283 | .Dq no . | ||
284 | .It Cm GlobalKnownHostsFile | ||
285 | Specifies a file to use for the global | ||
286 | host key database instead of | ||
287 | .Pa /etc/ssh/ssh_known_hosts . | ||
288 | .It Cm HostbasedAuthentication | ||
289 | Specifies whether to try rhosts based authentication with public key | ||
290 | authentication. | ||
291 | The argument must be | ||
292 | .Dq yes | ||
293 | or | ||
294 | .Dq no . | ||
295 | The default is | ||
296 | .Dq no . | ||
297 | This option applies to protocol version 2 only and | ||
298 | is similar to | ||
299 | .Cm RhostsRSAAuthentication . | ||
300 | .It Cm HostKeyAlgorithms | ||
301 | Specifies the protocol version 2 host key algorithms | ||
302 | that the client wants to use in order of preference. | ||
303 | The default for this option is: | ||
304 | .Dq ssh-rsa,ssh-dss . | ||
305 | .It Cm HostKeyAlias | ||
306 | Specifies an alias that should be used instead of the | ||
307 | real host name when looking up or saving the host key | ||
308 | in the host key database files. | ||
309 | This option is useful for tunneling ssh connections | ||
310 | or for multiple servers running on a single host. | ||
311 | .It Cm HostName | ||
312 | Specifies the real host name to log into. | ||
313 | This can be used to specify nicknames or abbreviations for hosts. | ||
314 | Default is the name given on the command line. | ||
315 | Numeric IP addresses are also permitted (both on the command line and in | ||
316 | .Cm HostName | ||
317 | specifications). | ||
318 | .It Cm IdentityFile | ||
319 | Specifies a file from which the user's RSA or DSA authentication identity | ||
320 | is read. The default is | ||
321 | .Pa $HOME/.ssh/identity | ||
322 | for protocol version 1, and | ||
323 | .Pa $HOME/.ssh/id_rsa | ||
324 | and | ||
325 | .Pa $HOME/.ssh/id_dsa | ||
326 | for protocol version 2. | ||
327 | Additionally, any identities represented by the authentication agent | ||
328 | will be used for authentication. | ||
329 | The file name may use the tilde | ||
330 | syntax to refer to a user's home directory. | ||
331 | It is possible to have | ||
332 | multiple identity files specified in configuration files; all these | ||
333 | identities will be tried in sequence. | ||
334 | .It Cm KeepAlive | ||
335 | Specifies whether the system should send TCP keepalive messages to the | ||
336 | other side. | ||
337 | If they are sent, death of the connection or crash of one | ||
338 | of the machines will be properly noticed. | ||
339 | However, this means that | ||
340 | connections will die if the route is down temporarily, and some people | ||
341 | find it annoying. | ||
342 | .Pp | ||
343 | The default is | ||
344 | .Dq yes | ||
345 | (to send keepalives), and the client will notice | ||
346 | if the network goes down or the remote host dies. | ||
347 | This is important in scripts, and many users want it too. | ||
348 | .Pp | ||
349 | To disable keepalives, the value should be set to | ||
350 | .Dq no . | ||
351 | .It Cm KerberosAuthentication | ||
352 | Specifies whether Kerberos authentication will be used. | ||
353 | The argument to this keyword must be | ||
354 | .Dq yes | ||
355 | or | ||
356 | .Dq no . | ||
357 | .It Cm KerberosTgtPassing | ||
358 | Specifies whether a Kerberos TGT will be forwarded to the server. | ||
359 | This will only work if the Kerberos server is actually an AFS kaserver. | ||
360 | The argument to this keyword must be | ||
361 | .Dq yes | ||
362 | or | ||
363 | .Dq no . | ||
364 | .It Cm LocalForward | ||
365 | Specifies that a TCP/IP port on the local machine be forwarded over | ||
366 | the secure channel to the specified host and port from the remote machine. | ||
367 | The first argument must be a port number, and the second must be | ||
368 | .Ar host:port . | ||
369 | IPv6 addresses can be specified with an alternative syntax: | ||
370 | .Ar host/port . | ||
371 | Multiple forwardings may be specified, and additional | ||
372 | forwardings can be given on the command line. | ||
373 | Only the superuser can forward privileged ports. | ||
374 | .It Cm LogLevel | ||
375 | Gives the verbosity level that is used when logging messages from | ||
376 | .Nm ssh . | ||
377 | The possible values are: | ||
378 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3. | ||
379 | The default is INFO. DEBUG and DEBUG1 are equivalent. DEBUG2 | ||
380 | and DEBUG3 each specify higher levels of verbose output. | ||
381 | .It Cm MACs | ||
382 | Specifies the MAC (message authentication code) algorithms | ||
383 | in order of preference. | ||
384 | The MAC algorithm is used in protocol version 2 | ||
385 | for data integrity protection. | ||
386 | Multiple algorithms must be comma-separated. | ||
387 | The default is | ||
388 | .Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 . | ||
389 | .It Cm NoHostAuthenticationForLocalhost | ||
390 | This option can be used if the home directory is shared across machines. | ||
391 | In this case localhost will refer to a different machine on each of | ||
392 | the machines and the user will get many warnings about changed host keys. | ||
393 | However, this option disables host authentication for localhost. | ||
394 | The argument to this keyword must be | ||
395 | .Dq yes | ||
396 | or | ||
397 | .Dq no . | ||
398 | The default is to check the host key for localhost. | ||
399 | .It Cm NumberOfPasswordPrompts | ||
400 | Specifies the number of password prompts before giving up. | ||
401 | The argument to this keyword must be an integer. | ||
402 | Default is 3. | ||
403 | .It Cm PasswordAuthentication | ||
404 | Specifies whether to use password authentication. | ||
405 | The argument to this keyword must be | ||
406 | .Dq yes | ||
407 | or | ||
408 | .Dq no . | ||
409 | The default is | ||
410 | .Dq yes . | ||
411 | .It Cm Port | ||
412 | Specifies the port number to connect on the remote host. | ||
413 | Default is 22. | ||
414 | .It Cm PreferredAuthentications | ||
415 | Specifies the order in which the client should try protocol 2 | ||
416 | authentication methods. This allows a client to prefer one method (e.g. | ||
417 | .Cm keyboard-interactive ) | ||
418 | over another method (e.g. | ||
419 | .Cm password ) | ||
420 | The default for this option is: | ||
421 | .Dq hostbased,publickey,keyboard-interactive,password . | ||
422 | .It Cm Protocol | ||
423 | Specifies the protocol versions | ||
424 | .Nm ssh | ||
425 | should support in order of preference. | ||
426 | The possible values are | ||
427 | .Dq 1 | ||
428 | and | ||
429 | .Dq 2 . | ||
430 | Multiple versions must be comma-separated. | ||
431 | The default is | ||
432 | .Dq 2,1 . | ||
433 | This means that | ||
434 | .Nm ssh | ||
435 | tries version 2 and falls back to version 1 | ||
436 | if version 2 is not available. | ||
437 | .It Cm ProxyCommand | ||
438 | Specifies the command to use to connect to the server. | ||
439 | The command | ||
440 | string extends to the end of the line, and is executed with | ||
441 | .Pa /bin/sh . | ||
442 | In the command string, | ||
443 | .Ql %h | ||
444 | will be substituted by the host name to | ||
445 | connect and | ||
446 | .Ql %p | ||
447 | by the port. | ||
448 | The command can be basically anything, | ||
449 | and should read from its standard input and write to its standard output. | ||
450 | It should eventually connect an | ||
451 | .Xr sshd 8 | ||
452 | server running on some machine, or execute | ||
453 | .Ic sshd -i | ||
454 | somewhere. | ||
455 | Host key management will be done using the | ||
456 | HostName of the host being connected (defaulting to the name typed by | ||
457 | the user). | ||
458 | Note that | ||
459 | .Cm CheckHostIP | ||
460 | is not available for connects with a proxy command. | ||
461 | .Pp | ||
462 | .It Cm PubkeyAuthentication | ||
463 | Specifies whether to try public key authentication. | ||
464 | The argument to this keyword must be | ||
465 | .Dq yes | ||
466 | or | ||
467 | .Dq no . | ||
468 | The default is | ||
469 | .Dq yes . | ||
470 | This option applies to protocol version 2 only. | ||
471 | .It Cm RemoteForward | ||
472 | Specifies that a TCP/IP port on the remote machine be forwarded over | ||
473 | the secure channel to the specified host and port from the local machine. | ||
474 | The first argument must be a port number, and the second must be | ||
475 | .Ar host:port . | ||
476 | IPv6 addresses can be specified with an alternative syntax: | ||
477 | .Ar host/port . | ||
478 | Multiple forwardings may be specified, and additional | ||
479 | forwardings can be given on the command line. | ||
480 | Only the superuser can forward privileged ports. | ||
481 | .It Cm RhostsAuthentication | ||
482 | Specifies whether to try rhosts based authentication. | ||
483 | Note that this | ||
484 | declaration only affects the client side and has no effect whatsoever | ||
485 | on security. | ||
486 | Most servers do not permit RhostsAuthentication because it | ||
487 | is not secure (see | ||
488 | .Cm RhostsRSAAuthentication ) . | ||
489 | The argument to this keyword must be | ||
490 | .Dq yes | ||
491 | or | ||
492 | .Dq no . | ||
493 | The default is | ||
494 | .Dq no . | ||
495 | This option applies to protocol version 1 only. | ||
496 | .It Cm RhostsRSAAuthentication | ||
497 | Specifies whether to try rhosts based authentication with RSA host | ||
498 | authentication. | ||
499 | The argument must be | ||
500 | .Dq yes | ||
501 | or | ||
502 | .Dq no . | ||
503 | The default is | ||
504 | .Dq no . | ||
505 | This option applies to protocol version 1 only and requires | ||
506 | .Nm ssh | ||
507 | to be setuid root. | ||
508 | .It Cm RSAAuthentication | ||
509 | Specifies whether to try RSA authentication. | ||
510 | The argument to this keyword must be | ||
511 | .Dq yes | ||
512 | or | ||
513 | .Dq no . | ||
514 | RSA authentication will only be | ||
515 | attempted if the identity file exists, or an authentication agent is | ||
516 | running. | ||
517 | The default is | ||
518 | .Dq yes . | ||
519 | Note that this option applies to protocol version 1 only. | ||
520 | .It Cm SmartcardDevice | ||
521 | Specifies which smartcard device to use. The argument to this keyword is | ||
522 | the device | ||
523 | .Nm ssh | ||
524 | should use to communicate with a smartcard used for storing the user's | ||
525 | private RSA key. By default, no device is specified and smartcard support | ||
526 | is not activated. | ||
527 | .It Cm StrictHostKeyChecking | ||
528 | If this flag is set to | ||
529 | .Dq yes , | ||
530 | .Nm ssh | ||
531 | will never automatically add host keys to the | ||
532 | .Pa $HOME/.ssh/known_hosts | ||
533 | file, and refuses to connect to hosts whose host key has changed. | ||
534 | This provides maximum protection against trojan horse attacks, | ||
535 | however, can be annoying when the | ||
536 | .Pa /etc/ssh/ssh_known_hosts | ||
537 | file is poorly maintained, or connections to new hosts are | ||
538 | frequently made. | ||
539 | This option forces the user to manually | ||
540 | add all new hosts. | ||
541 | If this flag is set to | ||
542 | .Dq no , | ||
543 | .Nm ssh | ||
544 | will automatically add new host keys to the | ||
545 | user known hosts files. | ||
546 | If this flag is set to | ||
547 | .Dq ask , | ||
548 | new host keys | ||
549 | will be added to the user known host files only after the user | ||
550 | has confirmed that is what they really want to do, and | ||
551 | .Nm ssh | ||
552 | will refuse to connect to hosts whose host key has changed. | ||
553 | The host keys of | ||
554 | known hosts will be verified automatically in all cases. | ||
555 | The argument must be | ||
556 | .Dq yes , | ||
557 | .Dq no | ||
558 | or | ||
559 | .Dq ask . | ||
560 | The default is | ||
561 | .Dq ask . | ||
562 | .It Cm UsePrivilegedPort | ||
563 | Specifies whether to use a privileged port for outgoing connections. | ||
564 | The argument must be | ||
565 | .Dq yes | ||
566 | or | ||
567 | .Dq no . | ||
568 | The default is | ||
569 | .Dq no . | ||
570 | Note that this option must be set to | ||
571 | .Dq yes | ||
572 | if | ||
573 | .Cm RhostsAuthentication | ||
574 | and | ||
575 | .Cm RhostsRSAAuthentication | ||
576 | authentications are needed with older servers. | ||
577 | .It Cm User | ||
578 | Specifies the user to log in as. | ||
579 | This can be useful when a different user name is used on different machines. | ||
580 | This saves the trouble of | ||
581 | having to remember to give the user name on the command line. | ||
582 | .It Cm UserKnownHostsFile | ||
583 | Specifies a file to use for the user | ||
584 | host key database instead of | ||
585 | .Pa $HOME/.ssh/known_hosts . | ||
586 | .It Cm XAuthLocation | ||
587 | Specifies the location of the | ||
588 | .Xr xauth 1 | ||
589 | program. | ||
590 | The default is | ||
591 | .Pa /usr/X11R6/bin/xauth . | ||
592 | .El | ||
593 | .Sh FILES | ||
594 | .Bl -tag -width Ds | ||
595 | .It Pa $HOME/.ssh/config | ||
596 | This is the per-user configuration file. | ||
597 | The format of this file is described above. | ||
598 | This file is used by the | ||
599 | .Nm ssh | ||
600 | client. | ||
601 | This file does not usually contain any sensitive information, | ||
602 | but the recommended permissions are read/write for the user, and not | ||
603 | accessible by others. | ||
604 | .It Pa /etc/ssh/ssh_config | ||
605 | Systemwide configuration file. | ||
606 | This file provides defaults for those | ||
607 | values that are not specified in the user's configuration file, and | ||
608 | for those users who do not have a configuration file. | ||
609 | This file must be world-readable. | ||
610 | .El | ||
611 | .Sh AUTHORS | ||
612 | OpenSSH is a derivative of the original and free | ||
613 | ssh 1.2.12 release by Tatu Ylonen. | ||
614 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | ||
615 | Theo de Raadt and Dug Song | ||
616 | removed many bugs, re-added newer features and | ||
617 | created OpenSSH. | ||
618 | Markus Friedl contributed the support for SSH | ||
619 | protocol versions 1.5 and 2.0. | ||
620 | .Sh SEE ALSO | ||
621 | .Xr ssh 1 | ||