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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 | .\" | |
47686178 | 37 | .\" $OpenBSD: ssh_config.5,v 1.105 2007/10/29 07:48:19 jmc Exp $ |
38 | .Dd $Mdocdate: December 2 2007 $ | |
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. | |
f5799ae1 | 106 | A single |
9108f8d9 | 107 | .Ql * |
f5799ae1 | 108 | as a pattern can be used to provide global |
109 | defaults for all hosts. | |
110 | The host is the | |
111 | .Ar hostname | |
9108f8d9 | 112 | argument given on the command line (i.e. the name is not converted to |
f5799ae1 | 113 | a canonicalized host name before matching). |
9108f8d9 | 114 | .Pp |
115 | See | |
116 | .Sx PATTERNS | |
117 | for more information on patterns. | |
0fff78ff | 118 | .It Cm AddressFamily |
119 | Specifies which address family to use when connecting. | |
120 | Valid arguments are | |
121 | .Dq any , | |
122 | .Dq inet | |
9108f8d9 | 123 | (use IPv4 only), or |
0fff78ff | 124 | .Dq inet6 |
996d5e62 | 125 | (use IPv6 only). |
f5799ae1 | 126 | .It Cm BatchMode |
127 | If set to | |
128 | .Dq yes , | |
129 | passphrase/password querying will be disabled. | |
130 | This option is useful in scripts and other batch jobs where no user | |
131 | is present to supply the password. | |
132 | The argument must be | |
133 | .Dq yes | |
134 | or | |
135 | .Dq no . | |
136 | The default is | |
137 | .Dq no . | |
138 | .It Cm BindAddress | |
665a873d | 139 | Use the specified address on the local machine as the source address of |
140 | the connection. | |
141 | Only useful on systems with more than one address. | |
f5799ae1 | 142 | Note that this option does not work if |
143 | .Cm UsePrivilegedPort | |
144 | is set to | |
145 | .Dq yes . | |
146 | .It Cm ChallengeResponseAuthentication | |
9108f8d9 | 147 | Specifies whether to use challenge-response authentication. |
f5799ae1 | 148 | The argument to this keyword must be |
149 | .Dq yes | |
150 | or | |
151 | .Dq no . | |
152 | The default is | |
153 | .Dq yes . | |
154 | .It Cm CheckHostIP | |
155 | If this flag is set to | |
156 | .Dq yes , | |
9108f8d9 | 157 | .Xr ssh 1 |
158 | will additionally check the host IP address in the | |
f5799ae1 | 159 | .Pa known_hosts |
160 | file. | |
161 | This allows ssh to detect if a host key changed due to DNS spoofing. | |
162 | If the option is set to | |
163 | .Dq no , | |
164 | the check will not be executed. | |
165 | The default is | |
166 | .Dq yes . | |
167 | .It Cm Cipher | |
168 | Specifies the cipher to use for encrypting the session | |
169 | in protocol version 1. | |
170 | Currently, | |
171 | .Dq blowfish , | |
172 | .Dq 3des , | |
173 | and | |
174 | .Dq des | |
175 | are supported. | |
176 | .Ar des | |
177 | is only supported in the | |
9108f8d9 | 178 | .Xr ssh 1 |
f5799ae1 | 179 | client for interoperability with legacy protocol 1 implementations |
180 | that do not support the | |
181 | .Ar 3des | |
6a9b3198 | 182 | cipher. |
183 | Its use is strongly discouraged due to cryptographic weaknesses. | |
f5799ae1 | 184 | The default is |
185 | .Dq 3des . | |
186 | .It Cm Ciphers | |
187 | Specifies the ciphers allowed for protocol version 2 | |
188 | in order of preference. | |
189 | Multiple ciphers must be comma-separated. | |
c9f39d2c | 190 | The supported ciphers are |
191 | .Dq 3des-cbc , | |
192 | .Dq aes128-cbc , | |
193 | .Dq aes192-cbc , | |
194 | .Dq aes256-cbc , | |
195 | .Dq aes128-ctr , | |
196 | .Dq aes192-ctr , | |
197 | .Dq aes256-ctr , | |
665a873d | 198 | .Dq arcfour128 , |
199 | .Dq arcfour256 , | |
c9f39d2c | 200 | .Dq arcfour , |
201 | .Dq blowfish-cbc , | |
202 | and | |
203 | .Dq cast128-cbc . | |
9108f8d9 | 204 | The default is: |
205 | .Bd -literal -offset 3n | |
206 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128, | |
207 | arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr, | |
208 | aes192-ctr,aes256-ctr | |
f5799ae1 | 209 | .Ed |
210 | .It Cm ClearAllForwardings | |
9108f8d9 | 211 | Specifies that all local, remote, and dynamic port forwardings |
f5799ae1 | 212 | specified in the configuration files or on the command line be |
6a9b3198 | 213 | cleared. |
214 | This option is primarily useful when used from the | |
9108f8d9 | 215 | .Xr ssh 1 |
f5799ae1 | 216 | command line to clear port forwardings set in |
217 | configuration files, and is automatically set by | |
218 | .Xr scp 1 | |
219 | and | |
220 | .Xr sftp 1 . | |
221 | The argument must be | |
222 | .Dq yes | |
223 | or | |
224 | .Dq no . | |
225 | The default is | |
226 | .Dq no . | |
227 | .It Cm Compression | |
228 | Specifies whether to use compression. | |
229 | The argument must be | |
230 | .Dq yes | |
231 | or | |
232 | .Dq no . | |
233 | The default is | |
234 | .Dq no . | |
235 | .It Cm CompressionLevel | |
236 | Specifies the compression level to use if compression is enabled. | |
237 | The argument must be an integer from 1 (fast) to 9 (slow, best). | |
238 | The default level is 6, which is good for most applications. | |
239 | The meaning of the values is the same as in | |
240 | .Xr gzip 1 . | |
241 | Note that this option applies to protocol version 1 only. | |
242 | .It Cm ConnectionAttempts | |
243 | Specifies the number of tries (one per second) to make before exiting. | |
244 | The argument must be an integer. | |
245 | This may be useful in scripts if the connection sometimes fails. | |
246 | The default is 1. | |
0fff78ff | 247 | .It Cm ConnectTimeout |
9108f8d9 | 248 | Specifies the timeout (in seconds) used when connecting to the |
249 | SSH server, instead of using the default system TCP timeout. | |
0fff78ff | 250 | This value is used only when the target is down or really unreachable, |
251 | not when it refuses the connection. | |
c9f39d2c | 252 | .It Cm ControlMaster |
253 | Enables the sharing of multiple sessions over a single network connection. | |
254 | When set to | |
9108f8d9 | 255 | .Dq yes , |
256 | .Xr ssh 1 | |
c9f39d2c | 257 | will listen for connections on a control socket specified using the |
258 | .Cm ControlPath | |
259 | argument. | |
260 | Additional sessions can connect to this socket using the same | |
261 | .Cm ControlPath | |
262 | with | |
263 | .Cm ControlMaster | |
264 | set to | |
265 | .Dq no | |
266 | (the default). | |
2c06c99b | 267 | These sessions will try to reuse the master instance's network connection |
268 | rather than initiating new ones, but will fall back to connecting normally | |
269 | if the control socket does not exist, or is not listening. | |
270 | .Pp | |
c9f39d2c | 271 | Setting this to |
272 | .Dq ask | |
9108f8d9 | 273 | will cause ssh |
c9f39d2c | 274 | to listen for control connections, but require confirmation using the |
275 | .Ev SSH_ASKPASS | |
276 | program before they are accepted (see | |
277 | .Xr ssh-add 1 | |
278 | for details). | |
665a873d | 279 | If the |
280 | .Cm ControlPath | |
9108f8d9 | 281 | cannot be opened, |
282 | ssh will continue without connecting to a master instance. | |
665a873d | 283 | .Pp |
284 | X11 and | |
285 | .Xr ssh-agent 1 | |
286 | forwarding is supported over these multiplexed connections, however the | |
2c06c99b | 287 | display and agent forwarded will be the one belonging to the master |
665a873d | 288 | connection i.e. it is not possible to forward multiple displays or agents. |
289 | .Pp | |
290 | Two additional options allow for opportunistic multiplexing: try to use a | |
291 | master connection but fall back to creating a new one if one does not already | |
292 | exist. | |
293 | These options are: | |
294 | .Dq auto | |
295 | and | |
296 | .Dq autoask . | |
297 | The latter requires confirmation like the | |
298 | .Dq ask | |
299 | option. | |
c9f39d2c | 300 | .It Cm ControlPath |
665a873d | 301 | Specify the path to the control socket used for connection sharing as described |
302 | in the | |
c9f39d2c | 303 | .Cm ControlMaster |
665a873d | 304 | section above or the string |
305 | .Dq none | |
306 | to disable connection sharing. | |
307 | In the path, | |
9108f8d9 | 308 | .Ql %l |
309 | will be substituted by the local host name, | |
665a873d | 310 | .Ql %h |
311 | will be substituted by the target host name, | |
312 | .Ql %p | |
9108f8d9 | 313 | the port, and |
665a873d | 314 | .Ql %r |
315 | by the remote login username. | |
316 | It is recommended that any | |
317 | .Cm ControlPath | |
318 | used for opportunistic connection sharing include | |
9108f8d9 | 319 | at least %h, %p, and %r. |
665a873d | 320 | This ensures that shared connections are uniquely identified. |
f5799ae1 | 321 | .It Cm DynamicForward |
2c06c99b | 322 | Specifies that a TCP port on the local machine be forwarded |
f5799ae1 | 323 | over the secure channel, and the application |
324 | protocol is then used to determine where to connect to from the | |
6a9b3198 | 325 | remote machine. |
2c06c99b | 326 | .Pp |
327 | The argument must be | |
328 | .Sm off | |
329 | .Oo Ar bind_address : Oc Ar port . | |
330 | .Sm on | |
331 | IPv6 addresses can be specified by enclosing addresses in square brackets or | |
332 | by using an alternative syntax: | |
333 | .Oo Ar bind_address Ns / Oc Ns Ar port . | |
334 | By default, the local port is bound in accordance with the | |
335 | .Cm GatewayPorts | |
336 | setting. | |
337 | However, an explicit | |
338 | .Ar bind_address | |
339 | may be used to bind the connection to a specific address. | |
340 | The | |
341 | .Ar bind_address | |
342 | of | |
343 | .Dq localhost | |
344 | indicates that the listening port be bound for local use only, while an | |
345 | empty address or | |
346 | .Sq * | |
347 | indicates that the port should be available from all interfaces. | |
348 | .Pp | |
0fff78ff | 349 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
9108f8d9 | 350 | .Xr ssh 1 |
0fff78ff | 351 | will act as a SOCKS server. |
f5799ae1 | 352 | Multiple forwardings may be specified, and |
6a9b3198 | 353 | additional forwardings can be given on the command line. |
354 | Only the superuser can forward privileged ports. | |
0fff78ff | 355 | .It Cm EnableSSHKeysign |
356 | Setting this option to | |
357 | .Dq yes | |
358 | in the global client configuration file | |
359 | .Pa /etc/ssh/ssh_config | |
360 | enables the use of the helper program | |
361 | .Xr ssh-keysign 8 | |
362 | during | |
363 | .Cm HostbasedAuthentication . | |
364 | The argument must be | |
365 | .Dq yes | |
366 | or | |
367 | .Dq no . | |
368 | The default is | |
369 | .Dq no . | |
cdd66111 | 370 | This option should be placed in the non-hostspecific section. |
0fff78ff | 371 | See |
372 | .Xr ssh-keysign 8 | |
373 | for more information. | |
f5799ae1 | 374 | .It Cm EscapeChar |
375 | Sets the escape character (default: | |
376 | .Ql ~ ) . | |
377 | The escape character can also | |
378 | be set on the command line. | |
379 | The argument should be a single character, | |
380 | .Ql ^ | |
381 | followed by a letter, or | |
382 | .Dq none | |
383 | to disable the escape | |
384 | character entirely (making the connection transparent for binary | |
385 | data). | |
9108f8d9 | 386 | .It Cm ExitOnForwardFailure |
387 | Specifies whether | |
388 | .Xr ssh 1 | |
389 | should terminate the connection if it cannot set up all requested | |
d4487008 | 390 | dynamic, tunnel, local, and remote port forwardings. |
9108f8d9 | 391 | The argument must be |
392 | .Dq yes | |
393 | or | |
394 | .Dq no . | |
395 | The default is | |
396 | .Dq no . | |
f5799ae1 | 397 | .It Cm ForwardAgent |
398 | Specifies whether the connection to the authentication agent (if any) | |
399 | will be forwarded to the remote machine. | |
400 | The argument must be | |
401 | .Dq yes | |
402 | or | |
403 | .Dq no . | |
404 | The default is | |
405 | .Dq no . | |
41b2f314 | 406 | .Pp |
6a9b3198 | 407 | Agent forwarding should be enabled with caution. |
408 | Users with the ability to bypass file permissions on the remote host | |
409 | (for the agent's Unix-domain socket) | |
410 | can access the local agent through the forwarded connection. | |
411 | An attacker cannot obtain key material from the agent, | |
41b2f314 | 412 | however they can perform operations on the keys that enable them to |
413 | authenticate using the identities loaded into the agent. | |
f5799ae1 | 414 | .It Cm ForwardX11 |
415 | Specifies whether X11 connections will be automatically redirected | |
416 | over the secure channel and | |
417 | .Ev DISPLAY | |
418 | set. | |
419 | The argument must be | |
420 | .Dq yes | |
421 | or | |
422 | .Dq no . | |
423 | The default is | |
424 | .Dq no . | |
41b2f314 | 425 | .Pp |
6a9b3198 | 426 | X11 forwarding should be enabled with caution. |
427 | Users with the ability to bypass file permissions on the remote host | |
cdd66111 | 428 | (for the user's X11 authorization database) |
6a9b3198 | 429 | can access the local X11 display through the forwarded connection. |
cdd66111 | 430 | An attacker may then be able to perform activities such as keystroke monitoring |
431 | if the | |
432 | .Cm ForwardX11Trusted | |
433 | option is also enabled. | |
434 | .It Cm ForwardX11Trusted | |
c9f39d2c | 435 | If this option is set to |
9108f8d9 | 436 | .Dq yes , |
437 | remote X11 clients will have full access to the original X11 display. | |
996d5e62 | 438 | .Pp |
cdd66111 | 439 | If this option is set to |
9108f8d9 | 440 | .Dq no , |
441 | remote X11 clients will be considered untrusted and prevented | |
cdd66111 | 442 | from stealing or tampering with data belonging to trusted X11 |
443 | clients. | |
996d5e62 | 444 | Furthermore, the |
445 | .Xr xauth 1 | |
446 | token used for the session will be set to expire after 20 minutes. | |
447 | Remote clients will be refused access after this time. | |
cdd66111 | 448 | .Pp |
449 | The default is | |
450 | .Dq no . | |
451 | .Pp | |
452 | See the X11 SECURITY extension specification for full details on | |
453 | the restrictions imposed on untrusted clients. | |
f5799ae1 | 454 | .It Cm GatewayPorts |
455 | Specifies whether remote hosts are allowed to connect to local | |
456 | forwarded ports. | |
457 | By default, | |
9108f8d9 | 458 | .Xr ssh 1 |
6a9b3198 | 459 | binds local port forwardings to the loopback address. |
460 | This prevents other remote hosts from connecting to forwarded ports. | |
f5799ae1 | 461 | .Cm GatewayPorts |
9108f8d9 | 462 | can be used to specify that ssh |
f5799ae1 | 463 | should bind local port forwardings to the wildcard address, |
464 | thus allowing remote hosts to connect to forwarded ports. | |
465 | The argument must be | |
466 | .Dq yes | |
467 | or | |
468 | .Dq no . | |
469 | The default is | |
470 | .Dq no . | |
471 | .It Cm GlobalKnownHostsFile | |
472 | Specifies a file to use for the global | |
473 | host key database instead of | |
474 | .Pa /etc/ssh/ssh_known_hosts . | |
0fff78ff | 475 | .It Cm GSSAPIAuthentication |
cdd66111 | 476 | Specifies whether user authentication based on GSSAPI is allowed. |
0fff78ff | 477 | The default is |
cdd66111 | 478 | .Dq no . |
0fff78ff | 479 | Note that this option applies to protocol version 2 only. |
480 | .It Cm GSSAPIDelegateCredentials | |
481 | Forward (delegate) credentials to the server. | |
482 | The default is | |
483 | .Dq no . | |
484 | Note that this option applies to protocol version 2 only. | |
996d5e62 | 485 | .It Cm HashKnownHosts |
486 | Indicates that | |
9108f8d9 | 487 | .Xr ssh 1 |
996d5e62 | 488 | should hash host names and addresses when they are added to |
665a873d | 489 | .Pa ~/.ssh/known_hosts . |
996d5e62 | 490 | These hashed names may be used normally by |
9108f8d9 | 491 | .Xr ssh 1 |
996d5e62 | 492 | and |
9108f8d9 | 493 | .Xr sshd 8 , |
996d5e62 | 494 | but they do not reveal identifying information should the file's contents |
495 | be disclosed. | |
496 | The default is | |
497 | .Dq no . | |
9108f8d9 | 498 | Note that existing names and addresses in known hosts files |
499 | will not be converted automatically, | |
500 | but may be manually hashed using | |
996d5e62 | 501 | .Xr ssh-keygen 1 . |
f5799ae1 | 502 | .It Cm HostbasedAuthentication |
503 | Specifies whether to try rhosts based authentication with public key | |
504 | authentication. | |
505 | The argument must be | |
506 | .Dq yes | |
507 | or | |
508 | .Dq no . | |
509 | The default is | |
510 | .Dq no . | |
511 | This option applies to protocol version 2 only and | |
512 | is similar to | |
513 | .Cm RhostsRSAAuthentication . | |
514 | .It Cm HostKeyAlgorithms | |
515 | Specifies the protocol version 2 host key algorithms | |
516 | that the client wants to use in order of preference. | |
517 | The default for this option is: | |
518 | .Dq ssh-rsa,ssh-dss . | |
519 | .It Cm HostKeyAlias | |
520 | Specifies an alias that should be used instead of the | |
521 | real host name when looking up or saving the host key | |
522 | in the host key database files. | |
9108f8d9 | 523 | This option is useful for tunneling SSH connections |
f5799ae1 | 524 | or for multiple servers running on a single host. |
525 | .It Cm HostName | |
526 | Specifies the real host name to log into. | |
527 | This can be used to specify nicknames or abbreviations for hosts. | |
9108f8d9 | 528 | The default is the name given on the command line. |
f5799ae1 | 529 | Numeric IP addresses are also permitted (both on the command line and in |
530 | .Cm HostName | |
531 | specifications). | |
99be0775 | 532 | .It Cm IdentitiesOnly |
533 | Specifies that | |
9108f8d9 | 534 | .Xr ssh 1 |
99be0775 | 535 | should only use the authentication identity files configured in the |
c9f39d2c | 536 | .Nm |
99be0775 | 537 | files, |
9108f8d9 | 538 | even if |
539 | .Xr ssh-agent 1 | |
99be0775 | 540 | offers more identities. |
541 | The argument to this keyword must be | |
542 | .Dq yes | |
543 | or | |
544 | .Dq no . | |
9108f8d9 | 545 | This option is intended for situations where ssh-agent |
99be0775 | 546 | offers many different identities. |
547 | The default is | |
548 | .Dq no . | |
2c06c99b | 549 | .It Cm IdentityFile |
550 | Specifies a file from which the user's RSA or DSA authentication identity | |
551 | is read. | |
552 | The default is | |
553 | .Pa ~/.ssh/identity | |
554 | for protocol version 1, and | |
555 | .Pa ~/.ssh/id_rsa | |
556 | and | |
557 | .Pa ~/.ssh/id_dsa | |
558 | for protocol version 2. | |
559 | Additionally, any identities represented by the authentication agent | |
560 | will be used for authentication. | |
9108f8d9 | 561 | .Pp |
2c06c99b | 562 | The file name may use the tilde |
9108f8d9 | 563 | syntax to refer to a user's home directory or one of the following |
564 | escape characters: | |
565 | .Ql %d | |
566 | (local user's home directory), | |
567 | .Ql %u | |
568 | (local user name), | |
569 | .Ql %l | |
570 | (local host name), | |
571 | .Ql %h | |
572 | (remote host name) or | |
573 | .Ql %r | |
574 | (remote user name). | |
575 | .Pp | |
2c06c99b | 576 | It is possible to have |
577 | multiple identity files specified in configuration files; all these | |
578 | identities will be tried in sequence. | |
47686178 | 579 | .It Cm KbdInteractiveAuthentication |
580 | Specifies whether to use keyboard-interactive authentication. | |
581 | The argument to this keyword must be | |
582 | .Dq yes | |
583 | or | |
584 | .Dq no . | |
585 | The default is | |
586 | .Dq yes . | |
996d5e62 | 587 | .It Cm KbdInteractiveDevices |
588 | Specifies the list of methods to use in keyboard-interactive authentication. | |
589 | Multiple method names must be comma-separated. | |
590 | The default is to use the server specified list. | |
9108f8d9 | 591 | The methods available vary depending on what the server supports. |
592 | For an OpenSSH server, | |
593 | it may be zero or more of: | |
594 | .Dq bsdauth , | |
595 | .Dq pam , | |
596 | and | |
597 | .Dq skey . | |
2c06c99b | 598 | .It Cm LocalCommand |
599 | Specifies a command to execute on the local machine after successfully | |
600 | connecting to the server. | |
601 | The command string extends to the end of the line, and is executed with | |
47686178 | 602 | the user's shell. |
2c06c99b | 603 | This directive is ignored unless |
604 | .Cm PermitLocalCommand | |
605 | has been enabled. | |
f5799ae1 | 606 | .It Cm LocalForward |
2c06c99b | 607 | Specifies that a TCP port on the local machine be forwarded over |
f5799ae1 | 608 | the secure channel to the specified host and port from the remote machine. |
dec6d9fe | 609 | The first argument must be |
996d5e62 | 610 | .Sm off |
dec6d9fe | 611 | .Oo Ar bind_address : Oc Ar port |
996d5e62 | 612 | .Sm on |
dec6d9fe | 613 | and the second argument must be |
614 | .Ar host : Ns Ar hostport . | |
996d5e62 | 615 | IPv6 addresses can be specified by enclosing addresses in square brackets or |
616 | by using an alternative syntax: | |
dec6d9fe | 617 | .Oo Ar bind_address Ns / Oc Ns Ar port |
618 | and | |
619 | .Ar host Ns / Ns Ar hostport . | |
996d5e62 | 620 | Multiple forwardings may be specified, and additional forwardings can be |
621 | given on the command line. | |
f5799ae1 | 622 | Only the superuser can forward privileged ports. |
996d5e62 | 623 | By default, the local port is bound in accordance with the |
624 | .Cm GatewayPorts | |
625 | setting. | |
626 | However, an explicit | |
627 | .Ar bind_address | |
628 | may be used to bind the connection to a specific address. | |
629 | The | |
630 | .Ar bind_address | |
631 | of | |
632 | .Dq localhost | |
633 | indicates that the listening port be bound for local use only, while an | |
634 | empty address or | |
635 | .Sq * | |
636 | indicates that the port should be available from all interfaces. | |
f5799ae1 | 637 | .It Cm LogLevel |
638 | Gives the verbosity level that is used when logging messages from | |
9108f8d9 | 639 | .Xr ssh 1 . |
f5799ae1 | 640 | The possible values are: |
9108f8d9 | 641 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
6a9b3198 | 642 | The default is INFO. |
643 | DEBUG and DEBUG1 are equivalent. | |
644 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. | |
f5799ae1 | 645 | .It Cm MACs |
646 | Specifies the MAC (message authentication code) algorithms | |
647 | in order of preference. | |
648 | The MAC algorithm is used in protocol version 2 | |
649 | for data integrity protection. | |
650 | Multiple algorithms must be comma-separated. | |
9108f8d9 | 651 | The default is: |
d4487008 | 652 | .Bd -literal -offset indent |
653 | hmac-md5,hmac-sha1,umac-64@openssh.com, | |
654 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 | |
655 | .Ed | |
f5799ae1 | 656 | .It Cm NoHostAuthenticationForLocalhost |
657 | This option can be used if the home directory is shared across machines. | |
658 | In this case localhost will refer to a different machine on each of | |
659 | the machines and the user will get many warnings about changed host keys. | |
660 | However, this option disables host authentication for localhost. | |
661 | The argument to this keyword must be | |
662 | .Dq yes | |
663 | or | |
664 | .Dq no . | |
665 | The default is to check the host key for localhost. | |
666 | .It Cm NumberOfPasswordPrompts | |
667 | Specifies the number of password prompts before giving up. | |
668 | The argument to this keyword must be an integer. | |
9108f8d9 | 669 | The default is 3. |
f5799ae1 | 670 | .It Cm PasswordAuthentication |
671 | Specifies whether to use password authentication. | |
672 | The argument to this keyword must be | |
673 | .Dq yes | |
674 | or | |
675 | .Dq no . | |
676 | The default is | |
677 | .Dq yes . | |
2c06c99b | 678 | .It Cm PermitLocalCommand |
679 | Allow local command execution via the | |
680 | .Ic LocalCommand | |
681 | option or using the | |
682 | .Ic !\& Ns Ar command | |
683 | escape sequence in | |
684 | .Xr ssh 1 . | |
685 | The argument must be | |
686 | .Dq yes | |
687 | or | |
688 | .Dq no . | |
689 | The default is | |
690 | .Dq no . | |
f5799ae1 | 691 | .It Cm Port |
692 | Specifies the port number to connect on the remote host. | |
9108f8d9 | 693 | The default is 22. |
f5799ae1 | 694 | .It Cm PreferredAuthentications |
695 | Specifies the order in which the client should try protocol 2 | |
0fff78ff | 696 | authentication methods. |
dec6d9fe | 697 | This allows a client to prefer one method (e.g.\& |
f5799ae1 | 698 | .Cm keyboard-interactive ) |
dec6d9fe | 699 | over another method (e.g.\& |
f5799ae1 | 700 | .Cm password ) |
701 | The default for this option is: | |
9108f8d9 | 702 | .Do gssapi-with-mic , |
703 | hostbased, | |
704 | publickey, | |
705 | keyboard-interactive, | |
706 | password | |
707 | .Dc . | |
f5799ae1 | 708 | .It Cm Protocol |
709 | Specifies the protocol versions | |
9108f8d9 | 710 | .Xr ssh 1 |
f5799ae1 | 711 | should support in order of preference. |
712 | The possible values are | |
9108f8d9 | 713 | .Sq 1 |
f5799ae1 | 714 | and |
9108f8d9 | 715 | .Sq 2 . |
f5799ae1 | 716 | Multiple versions must be comma-separated. |
717 | The default is | |
718 | .Dq 2,1 . | |
9108f8d9 | 719 | This means that ssh |
f5799ae1 | 720 | tries version 2 and falls back to version 1 |
721 | if version 2 is not available. | |
722 | .It Cm ProxyCommand | |
723 | Specifies the command to use to connect to the server. | |
724 | The command | |
725 | string extends to the end of the line, and is executed with | |
47686178 | 726 | the user's shell. |
f5799ae1 | 727 | In the command string, |
728 | .Ql %h | |
729 | will be substituted by the host name to | |
730 | connect and | |
731 | .Ql %p | |
732 | by the port. | |
733 | The command can be basically anything, | |
734 | and should read from its standard input and write to its standard output. | |
735 | It should eventually connect an | |
736 | .Xr sshd 8 | |
737 | server running on some machine, or execute | |
738 | .Ic sshd -i | |
739 | somewhere. | |
740 | Host key management will be done using the | |
741 | HostName of the host being connected (defaulting to the name typed by | |
742 | the user). | |
6a9b3198 | 743 | Setting the command to |
744 | .Dq none | |
745 | disables this option entirely. | |
f5799ae1 | 746 | Note that |
747 | .Cm CheckHostIP | |
748 | is not available for connects with a proxy command. | |
749 | .Pp | |
665a873d | 750 | This directive is useful in conjunction with |
751 | .Xr nc 1 | |
752 | and its proxy support. | |
753 | For example, the following directive would connect via an HTTP proxy at | |
754 | 192.0.2.0: | |
755 | .Bd -literal -offset 3n | |
756 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p | |
757 | .Ed | |
f5799ae1 | 758 | .It Cm PubkeyAuthentication |
759 | Specifies whether to try public key authentication. | |
760 | The argument to this keyword must be | |
761 | .Dq yes | |
762 | or | |
763 | .Dq no . | |
764 | The default is | |
765 | .Dq yes . | |
766 | This option applies to protocol version 2 only. | |
2c06c99b | 767 | .It Cm RekeyLimit |
768 | Specifies the maximum amount of data that may be transmitted before the | |
769 | session key is renegotiated. | |
770 | The argument is the number of bytes, with an optional suffix of | |
771 | .Sq K , | |
772 | .Sq M , | |
773 | or | |
774 | .Sq G | |
775 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. | |
776 | The default is between | |
9108f8d9 | 777 | .Sq 1G |
2c06c99b | 778 | and |
9108f8d9 | 779 | .Sq 4G , |
2c06c99b | 780 | depending on the cipher. |
781 | This option applies to protocol version 2 only. | |
f5799ae1 | 782 | .It Cm RemoteForward |
2c06c99b | 783 | Specifies that a TCP port on the remote machine be forwarded over |
f5799ae1 | 784 | the secure channel to the specified host and port from the local machine. |
dec6d9fe | 785 | The first argument must be |
996d5e62 | 786 | .Sm off |
dec6d9fe | 787 | .Oo Ar bind_address : Oc Ar port |
996d5e62 | 788 | .Sm on |
dec6d9fe | 789 | and the second argument must be |
790 | .Ar host : Ns Ar hostport . | |
791 | IPv6 addresses can be specified by enclosing addresses in square brackets | |
792 | or by using an alternative syntax: | |
793 | .Oo Ar bind_address Ns / Oc Ns Ar port | |
794 | and | |
795 | .Ar host Ns / Ns Ar hostport . | |
f5799ae1 | 796 | Multiple forwardings may be specified, and additional |
797 | forwardings can be given on the command line. | |
798 | Only the superuser can forward privileged ports. | |
996d5e62 | 799 | .Pp |
800 | If the | |
801 | .Ar bind_address | |
802 | is not specified, the default is to only bind to loopback addresses. | |
803 | If the | |
804 | .Ar bind_address | |
805 | is | |
806 | .Ql * | |
807 | or an empty string, then the forwarding is requested to listen on all | |
808 | interfaces. | |
809 | Specifying a remote | |
810 | .Ar bind_address | |
811 | will only succeed if the server's | |
812 | .Cm GatewayPorts | |
813 | option is enabled (see | |
814 | .Xr sshd_config 5 ) . | |
f5799ae1 | 815 | .It Cm RhostsRSAAuthentication |
816 | Specifies whether to try rhosts based authentication with RSA host | |
817 | authentication. | |
818 | The argument must be | |
819 | .Dq yes | |
820 | or | |
821 | .Dq no . | |
822 | The default is | |
823 | .Dq no . | |
824 | This option applies to protocol version 1 only and requires | |
9108f8d9 | 825 | .Xr ssh 1 |
f5799ae1 | 826 | to be setuid root. |
827 | .It Cm RSAAuthentication | |
828 | Specifies whether to try RSA authentication. | |
829 | The argument to this keyword must be | |
830 | .Dq yes | |
831 | or | |
832 | .Dq no . | |
833 | RSA authentication will only be | |
834 | attempted if the identity file exists, or an authentication agent is | |
835 | running. | |
836 | The default is | |
837 | .Dq yes . | |
838 | Note that this option applies to protocol version 1 only. | |
c9f39d2c | 839 | .It Cm SendEnv |
840 | Specifies what variables from the local | |
841 | .Xr environ 7 | |
842 | should be sent to the server. | |
9108f8d9 | 843 | Note that environment passing is only supported for protocol 2. |
844 | The server must also support it, and the server must be configured to | |
c9f39d2c | 845 | accept these environment variables. |
846 | Refer to | |
847 | .Cm AcceptEnv | |
848 | in | |
849 | .Xr sshd_config 5 | |
850 | for how to configure the server. | |
9108f8d9 | 851 | Variables are specified by name, which may contain wildcard characters. |
c9f39d2c | 852 | Multiple environment variables may be separated by whitespace or spread |
853 | across multiple | |
854 | .Cm SendEnv | |
855 | directives. | |
856 | The default is not to send any environment variables. | |
9108f8d9 | 857 | .Pp |
858 | See | |
859 | .Sx PATTERNS | |
860 | for more information on patterns. | |
cdd66111 | 861 | .It Cm ServerAliveCountMax |
2c06c99b | 862 | Sets the number of server alive messages (see below) which may be |
cdd66111 | 863 | sent without |
9108f8d9 | 864 | .Xr ssh 1 |
cdd66111 | 865 | receiving any messages back from the server. |
866 | If this threshold is reached while server alive messages are being sent, | |
9108f8d9 | 867 | ssh will disconnect from the server, terminating the session. |
cdd66111 | 868 | It is important to note that the use of server alive messages is very |
869 | different from | |
870 | .Cm TCPKeepAlive | |
871 | (below). | |
872 | The server alive messages are sent through the encrypted channel | |
873 | and therefore will not be spoofable. | |
874 | The TCP keepalive option enabled by | |
875 | .Cm TCPKeepAlive | |
876 | is spoofable. | |
877 | The server alive mechanism is valuable when the client or | |
878 | server depend on knowing when a connection has become inactive. | |
879 | .Pp | |
880 | The default value is 3. | |
881 | If, for example, | |
882 | .Cm ServerAliveInterval | |
9108f8d9 | 883 | (see below) is set to 15 and |
cdd66111 | 884 | .Cm ServerAliveCountMax |
9108f8d9 | 885 | is left at the default, if the server becomes unresponsive, |
886 | ssh will disconnect after approximately 45 seconds. | |
887 | This option applies to protocol version 2 only. | |
2c06c99b | 888 | .It Cm ServerAliveInterval |
889 | Sets a timeout interval in seconds after which if no data has been received | |
890 | from the server, | |
9108f8d9 | 891 | .Xr ssh 1 |
2c06c99b | 892 | will send a message through the encrypted |
893 | channel to request a response from the server. | |
894 | The default | |
895 | is 0, indicating that these messages will not be sent to the server. | |
896 | This option applies to protocol version 2 only. | |
f5799ae1 | 897 | .It Cm SmartcardDevice |
0fff78ff | 898 | Specifies which smartcard device to use. |
899 | The argument to this keyword is the device | |
9108f8d9 | 900 | .Xr ssh 1 |
f5799ae1 | 901 | should use to communicate with a smartcard used for storing the user's |
0fff78ff | 902 | private RSA key. |
903 | By default, no device is specified and smartcard support is not activated. | |
f5799ae1 | 904 | .It Cm StrictHostKeyChecking |
905 | If this flag is set to | |
906 | .Dq yes , | |
9108f8d9 | 907 | .Xr ssh 1 |
f5799ae1 | 908 | will never automatically add host keys to the |
665a873d | 909 | .Pa ~/.ssh/known_hosts |
f5799ae1 | 910 | file, and refuses to connect to hosts whose host key has changed. |
911 | This provides maximum protection against trojan horse attacks, | |
9108f8d9 | 912 | though it can be annoying when the |
f5799ae1 | 913 | .Pa /etc/ssh/ssh_known_hosts |
9108f8d9 | 914 | file is poorly maintained or when connections to new hosts are |
f5799ae1 | 915 | frequently made. |
916 | This option forces the user to manually | |
917 | add all new hosts. | |
918 | If this flag is set to | |
919 | .Dq no , | |
9108f8d9 | 920 | ssh will automatically add new host keys to the |
f5799ae1 | 921 | user known hosts files. |
922 | If this flag is set to | |
923 | .Dq ask , | |
924 | new host keys | |
925 | will be added to the user known host files only after the user | |
926 | has confirmed that is what they really want to do, and | |
9108f8d9 | 927 | ssh will refuse to connect to hosts whose host key has changed. |
f5799ae1 | 928 | The host keys of |
929 | known hosts will be verified automatically in all cases. | |
930 | The argument must be | |
931 | .Dq yes , | |
9108f8d9 | 932 | .Dq no , |
f5799ae1 | 933 | or |
934 | .Dq ask . | |
935 | The default is | |
936 | .Dq ask . | |
cdd66111 | 937 | .It Cm TCPKeepAlive |
938 | Specifies whether the system should send TCP keepalive messages to the | |
939 | other side. | |
940 | If they are sent, death of the connection or crash of one | |
941 | of the machines will be properly noticed. | |
942 | However, this means that | |
943 | connections will die if the route is down temporarily, and some people | |
944 | find it annoying. | |
945 | .Pp | |
946 | The default is | |
947 | .Dq yes | |
948 | (to send TCP keepalive messages), and the client will notice | |
949 | if the network goes down or the remote host dies. | |
950 | This is important in scripts, and many users want it too. | |
951 | .Pp | |
952 | To disable TCP keepalive messages, the value should be set to | |
953 | .Dq no . | |
2c06c99b | 954 | .It Cm Tunnel |
9108f8d9 | 955 | Request |
2c06c99b | 956 | .Xr tun 4 |
957 | device forwarding between the client and the server. | |
2c06c99b | 958 | The argument must be |
959 | .Dq yes , | |
9108f8d9 | 960 | .Dq point-to-point |
961 | (layer 3), | |
2c06c99b | 962 | .Dq ethernet |
9108f8d9 | 963 | (layer 2), |
2c06c99b | 964 | or |
965 | .Dq no . | |
9108f8d9 | 966 | Specifying |
967 | .Dq yes | |
968 | requests the default tunnel mode, which is | |
969 | .Dq point-to-point . | |
2c06c99b | 970 | The default is |
971 | .Dq no . | |
972 | .It Cm TunnelDevice | |
9108f8d9 | 973 | Specifies the |
2c06c99b | 974 | .Xr tun 4 |
9108f8d9 | 975 | devices to open on the client |
976 | .Pq Ar local_tun | |
977 | and the server | |
978 | .Pq Ar remote_tun . | |
979 | .Pp | |
980 | The argument must be | |
981 | .Sm off | |
982 | .Ar local_tun Op : Ar remote_tun . | |
983 | .Sm on | |
984 | The devices may be specified by numerical ID or the keyword | |
985 | .Dq any , | |
986 | which uses the next available tunnel device. | |
987 | If | |
988 | .Ar remote_tun | |
989 | is not specified, it defaults to | |
990 | .Dq any . | |
991 | The default is | |
992 | .Dq any:any . | |
f5799ae1 | 993 | .It Cm UsePrivilegedPort |
994 | Specifies whether to use a privileged port for outgoing connections. | |
995 | The argument must be | |
996 | .Dq yes | |
997 | or | |
998 | .Dq no . | |
999 | The default is | |
1000 | .Dq no . | |
41b2f314 | 1001 | If set to |
9108f8d9 | 1002 | .Dq yes , |
1003 | .Xr ssh 1 | |
41b2f314 | 1004 | must be setuid root. |
f5799ae1 | 1005 | Note that this option must be set to |
1006 | .Dq yes | |
0fff78ff | 1007 | for |
f5799ae1 | 1008 | .Cm RhostsRSAAuthentication |
0fff78ff | 1009 | with older servers. |
f5799ae1 | 1010 | .It Cm User |
1011 | Specifies the user to log in as. | |
1012 | This can be useful when a different user name is used on different machines. | |
1013 | This saves the trouble of | |
1014 | having to remember to give the user name on the command line. | |
1015 | .It Cm UserKnownHostsFile | |
1016 | Specifies a file to use for the user | |
1017 | host key database instead of | |
665a873d | 1018 | .Pa ~/.ssh/known_hosts . |
0fff78ff | 1019 | .It Cm VerifyHostKeyDNS |
1020 | Specifies whether to verify the remote key using DNS and SSHFP resource | |
1021 | records. | |
cdd66111 | 1022 | If this option is set to |
1023 | .Dq yes , | |
1024 | the client will implicitly trust keys that match a secure fingerprint | |
1025 | from DNS. | |
1026 | Insecure fingerprints will be handled as if this option was set to | |
1027 | .Dq ask . | |
1028 | If this option is set to | |
1029 | .Dq ask , | |
1030 | information on fingerprint match will be displayed, but the user will still | |
1031 | need to confirm new host keys according to the | |
1032 | .Cm StrictHostKeyChecking | |
1033 | option. | |
1034 | The argument must be | |
1035 | .Dq yes , | |
9108f8d9 | 1036 | .Dq no , |
cdd66111 | 1037 | or |
1038 | .Dq ask . | |
0fff78ff | 1039 | The default is |
1040 | .Dq no . | |
1041 | Note that this option applies to protocol version 2 only. | |
9108f8d9 | 1042 | .Pp |
1043 | See also | |
1044 | .Sx VERIFYING HOST KEYS | |
1045 | in | |
1046 | .Xr ssh 1 . | |
f5799ae1 | 1047 | .It Cm XAuthLocation |
41b2f314 | 1048 | Specifies the full pathname of the |
f5799ae1 | 1049 | .Xr xauth 1 |
1050 | program. | |
1051 | The default is | |
1052 | .Pa /usr/X11R6/bin/xauth . | |
1053 | .El | |
9108f8d9 | 1054 | .Sh PATTERNS |
1055 | A | |
1056 | .Em pattern | |
1057 | consists of zero or more non-whitespace characters, | |
1058 | .Sq * | |
1059 | (a wildcard that matches zero or more characters), | |
1060 | or | |
1061 | .Sq ?\& | |
1062 | (a wildcard that matches exactly one character). | |
1063 | For example, to specify a set of declarations for any host in the | |
1064 | .Dq .co.uk | |
1065 | set of domains, | |
1066 | the following pattern could be used: | |
1067 | .Pp | |
1068 | .Dl Host *.co.uk | |
1069 | .Pp | |
1070 | The following pattern | |
1071 | would match any host in the 192.168.0.[0-9] network range: | |
1072 | .Pp | |
1073 | .Dl Host 192.168.0.? | |
1074 | .Pp | |
1075 | A | |
1076 | .Em pattern-list | |
1077 | is a comma-separated list of patterns. | |
1078 | Patterns within pattern-lists may be negated | |
1079 | by preceding them with an exclamation mark | |
1080 | .Pq Sq !\& . | |
1081 | For example, | |
1082 | to allow a key to be used from anywhere within an organisation | |
1083 | except from the | |
1084 | .Dq dialup | |
1085 | pool, | |
1086 | the following entry (in authorized_keys) could be used: | |
1087 | .Pp | |
1088 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" | |
f5799ae1 | 1089 | .Sh FILES |
1090 | .Bl -tag -width Ds | |
665a873d | 1091 | .It Pa ~/.ssh/config |
f5799ae1 | 1092 | This is the per-user configuration file. |
1093 | The format of this file is described above. | |
9108f8d9 | 1094 | This file is used by the SSH client. |
c9f39d2c | 1095 | Because of the potential for abuse, this file must have strict permissions: |
1096 | read/write for the user, and not accessible by others. | |
f5799ae1 | 1097 | .It Pa /etc/ssh/ssh_config |
1098 | Systemwide configuration file. | |
1099 | This file provides defaults for those | |
1100 | values that are not specified in the user's configuration file, and | |
1101 | for those users who do not have a configuration file. | |
1102 | This file must be world-readable. | |
1103 | .El | |
0fff78ff | 1104 | .Sh SEE ALSO |
1105 | .Xr ssh 1 | |
f5799ae1 | 1106 | .Sh AUTHORS |
1107 | OpenSSH is a derivative of the original and free | |
1108 | ssh 1.2.12 release by Tatu Ylonen. | |
1109 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
1110 | Theo de Raadt and Dug Song | |
1111 | removed many bugs, re-added newer features and | |
1112 | created OpenSSH. | |
1113 | Markus Friedl contributed the support for SSH | |
1114 | protocol versions 1.5 and 2.0. |