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f5799ae1 | 1 | .\" -*- nroff -*- |
2 | .\" | |
3 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | .\" All rights reserved | |
6 | .\" | |
7 | .\" As far as I am concerned, the code I have written for this software | |
8 | .\" can be used freely for any purpose. Any derived versions of this | |
9 | .\" software must be clearly marked as such, and if the derived work is | |
10 | .\" incompatible with the protocol description in the RFC file, it must be | |
11 | .\" called by a name other than "ssh" or "Secure Shell". | |
12 | .\" | |
13 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. | |
14 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. | |
15 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. | |
16 | .\" | |
17 | .\" Redistribution and use in source and binary forms, with or without | |
18 | .\" modification, are permitted provided that the following conditions | |
19 | .\" are met: | |
20 | .\" 1. Redistributions of source code must retain the above copyright | |
21 | .\" notice, this list of conditions and the following disclaimer. | |
22 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
23 | .\" notice, this list of conditions and the following disclaimer in the | |
24 | .\" documentation and/or other materials provided with the distribution. | |
25 | .\" | |
26 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
27 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
28 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
29 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
30 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
31 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
32 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
33 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
34 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
35 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
36 | .\" | |
91d9cdd3 | 37 | .\" $OpenBSD: sshd_config.5,v 1.102 2009/02/22 23:59:25 djm Exp $ |
38 | .Dd $Mdocdate: February 22 2009 $ | |
f5799ae1 | 39 | .Dt SSHD_CONFIG 5 |
40 | .Os | |
41 | .Sh NAME | |
42 | .Nm sshd_config | |
43 | .Nd OpenSSH SSH daemon configuration file | |
44 | .Sh SYNOPSIS | |
799ae497 | 45 | .Nm /etc/ssh/sshd_config |
f5799ae1 | 46 | .Sh DESCRIPTION |
9108f8d9 | 47 | .Xr sshd 8 |
f5799ae1 | 48 | reads configuration data from |
49 | .Pa /etc/ssh/sshd_config | |
50 | (or the file specified with | |
51 | .Fl f | |
52 | on the command line). | |
53 | The file contains keyword-argument pairs, one per line. | |
54 | Lines starting with | |
55 | .Ql # | |
56 | and empty lines are interpreted as comments. | |
9108f8d9 | 57 | Arguments may optionally be enclosed in double quotes |
58 | .Pq \&" | |
59 | in order to represent arguments containing spaces. | |
f5799ae1 | 60 | .Pp |
61 | The possible | |
62 | keywords and their meanings are as follows (note that | |
63 | keywords are case-insensitive and arguments are case-sensitive): | |
64 | .Bl -tag -width Ds | |
c9f39d2c | 65 | .It Cm AcceptEnv |
66 | Specifies what environment variables sent by the client will be copied into | |
67 | the session's | |
68 | .Xr environ 7 . | |
69 | See | |
70 | .Cm SendEnv | |
71 | in | |
72 | .Xr ssh_config 5 | |
73 | for how to configure the client. | |
74 | Note that environment passing is only supported for protocol 2. | |
75 | Variables are specified by name, which may contain the wildcard characters | |
9108f8d9 | 76 | .Ql * |
c9f39d2c | 77 | and |
78 | .Ql \&? . | |
79 | Multiple environment variables may be separated by whitespace or spread | |
80 | across multiple | |
81 | .Cm AcceptEnv | |
82 | directives. | |
83 | Be warned that some environment variables could be used to bypass restricted | |
84 | user environments. | |
85 | For this reason, care should be taken in the use of this directive. | |
86 | The default is not to accept any environment variables. | |
996d5e62 | 87 | .It Cm AddressFamily |
88 | Specifies which address family should be used by | |
9108f8d9 | 89 | .Xr sshd 8 . |
996d5e62 | 90 | Valid arguments are |
91 | .Dq any , | |
92 | .Dq inet | |
9108f8d9 | 93 | (use IPv4 only), or |
996d5e62 | 94 | .Dq inet6 |
95 | (use IPv6 only). | |
96 | The default is | |
97 | .Dq any . | |
22616013 | 98 | .It Cm AllowAgentForwarding |
99 | Specifies whether | |
100 | .Xr ssh-agent 1 | |
101 | forwarding is permitted. | |
102 | The default is | |
103 | .Dq yes . | |
104 | Note that disabling agent forwarding does not improve security | |
105 | unless users are also denied shell access, as they can always install | |
106 | their own forwarders. | |
f5799ae1 | 107 | .It Cm AllowGroups |
108 | This keyword can be followed by a list of group name patterns, separated | |
109 | by spaces. | |
110 | If specified, login is allowed only for users whose primary | |
111 | group or supplementary group list matches one of the patterns. | |
f5799ae1 | 112 | Only group names are valid; a numerical group ID is not recognized. |
113 | By default, login is allowed for all groups. | |
9108f8d9 | 114 | The allow/deny directives are processed in the following order: |
115 | .Cm DenyUsers , | |
116 | .Cm AllowUsers , | |
117 | .Cm DenyGroups , | |
118 | and finally | |
119 | .Cm AllowGroups . | |
120 | .Pp | |
121 | See | |
122 | .Sx PATTERNS | |
123 | in | |
124 | .Xr ssh_config 5 | |
125 | for more information on patterns. | |
f5799ae1 | 126 | .It Cm AllowTcpForwarding |
127 | Specifies whether TCP forwarding is permitted. | |
128 | The default is | |
129 | .Dq yes . | |
130 | Note that disabling TCP forwarding does not improve security unless | |
131 | users are also denied shell access, as they can always install their | |
132 | own forwarders. | |
f5799ae1 | 133 | .It Cm AllowUsers |
134 | This keyword can be followed by a list of user name patterns, separated | |
135 | by spaces. | |
6a9b3198 | 136 | If specified, login is allowed only for user names that |
f5799ae1 | 137 | match one of the patterns. |
f5799ae1 | 138 | Only user names are valid; a numerical user ID is not recognized. |
139 | By default, login is allowed for all users. | |
140 | If the pattern takes the form USER@HOST then USER and HOST | |
141 | are separately checked, restricting logins to particular | |
142 | users from particular hosts. | |
9108f8d9 | 143 | The allow/deny directives are processed in the following order: |
144 | .Cm DenyUsers , | |
145 | .Cm AllowUsers , | |
146 | .Cm DenyGroups , | |
147 | and finally | |
148 | .Cm AllowGroups . | |
149 | .Pp | |
150 | See | |
151 | .Sx PATTERNS | |
152 | in | |
153 | .Xr ssh_config 5 | |
154 | for more information on patterns. | |
f5799ae1 | 155 | .It Cm AuthorizedKeysFile |
156 | Specifies the file that contains the public keys that can be used | |
157 | for user authentication. | |
158 | .Cm AuthorizedKeysFile | |
159 | may contain tokens of the form %T which are substituted during connection | |
9108f8d9 | 160 | setup. |
0fff78ff | 161 | The following tokens are defined: %% is replaced by a literal '%', |
9108f8d9 | 162 | %h is replaced by the home directory of the user being authenticated, and |
f5799ae1 | 163 | %u is replaced by the username of that user. |
164 | After expansion, | |
165 | .Cm AuthorizedKeysFile | |
166 | is taken to be an absolute path or one relative to the user's home | |
167 | directory. | |
168 | The default is | |
169 | .Dq .ssh/authorized_keys . | |
170 | .It Cm Banner | |
f5799ae1 | 171 | The contents of the specified file are sent to the remote user before |
172 | authentication is allowed. | |
47686178 | 173 | If the argument is |
174 | .Dq none | |
175 | then no banner is displayed. | |
f5799ae1 | 176 | This option is only available for protocol version 2. |
177 | By default, no banner is displayed. | |
f5799ae1 | 178 | .It Cm ChallengeResponseAuthentication |
9108f8d9 | 179 | Specifies whether challenge-response authentication is allowed. |
f5799ae1 | 180 | All authentication styles from |
181 | .Xr login.conf 5 | |
182 | are supported. | |
183 | The default is | |
184 | .Dq yes . | |
47686178 | 185 | .It Cm ChrootDirectory |
186 | Specifies a path to | |
187 | .Xr chroot 2 | |
188 | to after authentication. | |
189 | This path, and all its components, must be root-owned directories that are | |
190 | not writable by any other user or group. | |
191 | .Pp | |
192 | The path may contain the following tokens that are expanded at runtime once | |
193 | the connecting user has been authenticated: %% is replaced by a literal '%', | |
194 | %h is replaced by the home directory of the user being authenticated, and | |
195 | %u is replaced by the username of that user. | |
196 | .Pp | |
197 | The | |
198 | .Cm ChrootDirectory | |
199 | must contain the necessary files and directories to support the | |
200 | users' session. | |
201 | For an interactive session this requires at least a shell, typically | |
202 | .Xr sh 1 , | |
203 | and basic | |
204 | .Pa /dev | |
205 | nodes such as | |
206 | .Xr null 4 , | |
207 | .Xr zero 4 , | |
208 | .Xr stdin 4 , | |
209 | .Xr stdout 4 , | |
210 | .Xr stderr 4 , | |
211 | .Xr arandom 4 | |
212 | and | |
213 | .Xr tty 4 | |
214 | devices. | |
215 | For file transfer sessions using | |
216 | .Dq sftp , | |
217 | no additional configuration of the environment is necessary if the | |
218 | in-process sftp server is used (see | |
219 | .Cm Subsystem | |
220 | for details). | |
221 | .Pp | |
222 | The default is not to | |
223 | .Xr chroot 2 . | |
f5799ae1 | 224 | .It Cm Ciphers |
225 | Specifies the ciphers allowed for protocol version 2. | |
226 | Multiple ciphers must be comma-separated. | |
c9f39d2c | 227 | The supported ciphers are |
228 | .Dq 3des-cbc , | |
229 | .Dq aes128-cbc , | |
230 | .Dq aes192-cbc , | |
231 | .Dq aes256-cbc , | |
232 | .Dq aes128-ctr , | |
233 | .Dq aes192-ctr , | |
234 | .Dq aes256-ctr , | |
665a873d | 235 | .Dq arcfour128 , |
236 | .Dq arcfour256 , | |
c9f39d2c | 237 | .Dq arcfour , |
238 | .Dq blowfish-cbc , | |
239 | and | |
240 | .Dq cast128-cbc . | |
9108f8d9 | 241 | The default is: |
242 | .Bd -literal -offset 3n | |
91d9cdd3 | 243 | aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, |
244 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc, | |
245 | aes256-cbc,arcfour | |
f5799ae1 | 246 | .Ed |
f5799ae1 | 247 | .It Cm ClientAliveCountMax |
2c06c99b | 248 | Sets the number of client alive messages (see below) which may be |
f5799ae1 | 249 | sent without |
9108f8d9 | 250 | .Xr sshd 8 |
0fff78ff | 251 | receiving any messages back from the client. |
252 | If this threshold is reached while client alive messages are being sent, | |
9108f8d9 | 253 | sshd will disconnect the client, terminating the session. |
0fff78ff | 254 | It is important to note that the use of client alive messages is very |
255 | different from | |
cdd66111 | 256 | .Cm TCPKeepAlive |
0fff78ff | 257 | (below). |
258 | The client alive messages are sent through the encrypted channel | |
259 | and therefore will not be spoofable. | |
260 | The TCP keepalive option enabled by | |
cdd66111 | 261 | .Cm TCPKeepAlive |
0fff78ff | 262 | is spoofable. |
263 | The client alive mechanism is valuable when the client or | |
f5799ae1 | 264 | server depend on knowing when a connection has become inactive. |
265 | .Pp | |
0fff78ff | 266 | The default value is 3. |
267 | If | |
f5799ae1 | 268 | .Cm ClientAliveInterval |
2c06c99b | 269 | (see below) is set to 15, and |
f5799ae1 | 270 | .Cm ClientAliveCountMax |
9108f8d9 | 271 | is left at the default, unresponsive SSH clients |
f5799ae1 | 272 | will be disconnected after approximately 45 seconds. |
9108f8d9 | 273 | This option applies to protocol version 2 only. |
665a873d | 274 | .It Cm ClientAliveInterval |
275 | Sets a timeout interval in seconds after which if no data has been received | |
276 | from the client, | |
9108f8d9 | 277 | .Xr sshd 8 |
665a873d | 278 | will send a message through the encrypted |
279 | channel to request a response from the client. | |
280 | The default | |
281 | is 0, indicating that these messages will not be sent to the client. | |
282 | This option applies to protocol version 2 only. | |
f5799ae1 | 283 | .It Cm Compression |
665a873d | 284 | Specifies whether compression is allowed, or delayed until |
285 | the user has authenticated successfully. | |
f5799ae1 | 286 | The argument must be |
665a873d | 287 | .Dq yes , |
288 | .Dq delayed , | |
f5799ae1 | 289 | or |
290 | .Dq no . | |
291 | The default is | |
665a873d | 292 | .Dq delayed . |
f5799ae1 | 293 | .It Cm DenyGroups |
294 | This keyword can be followed by a list of group name patterns, separated | |
295 | by spaces. | |
296 | Login is disallowed for users whose primary group or supplementary | |
297 | group list matches one of the patterns. | |
f5799ae1 | 298 | Only group names are valid; a numerical group ID is not recognized. |
299 | By default, login is allowed for all groups. | |
9108f8d9 | 300 | The allow/deny directives are processed in the following order: |
301 | .Cm DenyUsers , | |
302 | .Cm AllowUsers , | |
303 | .Cm DenyGroups , | |
304 | and finally | |
305 | .Cm AllowGroups . | |
306 | .Pp | |
307 | See | |
308 | .Sx PATTERNS | |
309 | in | |
310 | .Xr ssh_config 5 | |
311 | for more information on patterns. | |
f5799ae1 | 312 | .It Cm DenyUsers |
313 | This keyword can be followed by a list of user name patterns, separated | |
314 | by spaces. | |
315 | Login is disallowed for user names that match one of the patterns. | |
f5799ae1 | 316 | Only user names are valid; a numerical user ID is not recognized. |
317 | By default, login is allowed for all users. | |
318 | If the pattern takes the form USER@HOST then USER and HOST | |
319 | are separately checked, restricting logins to particular | |
320 | users from particular hosts. | |
9108f8d9 | 321 | The allow/deny directives are processed in the following order: |
322 | .Cm DenyUsers , | |
323 | .Cm AllowUsers , | |
324 | .Cm DenyGroups , | |
325 | and finally | |
326 | .Cm AllowGroups . | |
327 | .Pp | |
328 | See | |
329 | .Sx PATTERNS | |
330 | in | |
331 | .Xr ssh_config 5 | |
332 | for more information on patterns. | |
333 | .It Cm ForceCommand | |
334 | Forces the execution of the command specified by | |
335 | .Cm ForceCommand , | |
47686178 | 336 | ignoring any command supplied by the client and |
337 | .Pa ~/.ssh/rc | |
338 | if present. | |
9108f8d9 | 339 | The command is invoked by using the user's login shell with the -c option. |
340 | This applies to shell, command, or subsystem execution. | |
341 | It is most useful inside a | |
342 | .Cm Match | |
343 | block. | |
344 | The command originally supplied by the client is available in the | |
345 | .Ev SSH_ORIGINAL_COMMAND | |
346 | environment variable. | |
47686178 | 347 | Specifying a command of |
348 | .Dq internal-sftp | |
349 | will force the use of an in-process sftp server that requires no support | |
350 | files when used with | |
351 | .Cm ChrootDirectory . | |
f5799ae1 | 352 | .It Cm GatewayPorts |
353 | Specifies whether remote hosts are allowed to connect to ports | |
354 | forwarded for the client. | |
355 | By default, | |
9108f8d9 | 356 | .Xr sshd 8 |
6a9b3198 | 357 | binds remote port forwardings to the loopback address. |
358 | This prevents other remote hosts from connecting to forwarded ports. | |
f5799ae1 | 359 | .Cm GatewayPorts |
9108f8d9 | 360 | can be used to specify that sshd |
996d5e62 | 361 | should allow remote port forwardings to bind to non-loopback addresses, thus |
362 | allowing other hosts to connect. | |
363 | The argument may be | |
364 | .Dq no | |
365 | to force remote port forwardings to be available to the local host only, | |
f5799ae1 | 366 | .Dq yes |
996d5e62 | 367 | to force remote port forwardings to bind to the wildcard address, or |
368 | .Dq clientspecified | |
369 | to allow the client to select the address to which the forwarding is bound. | |
f5799ae1 | 370 | The default is |
371 | .Dq no . | |
0fff78ff | 372 | .It Cm GSSAPIAuthentication |
373 | Specifies whether user authentication based on GSSAPI is allowed. | |
cdd66111 | 374 | The default is |
0fff78ff | 375 | .Dq no . |
376 | Note that this option applies to protocol version 2 only. | |
f97edba6 | 377 | .It Cm GSSAPIKeyExchange |
378 | Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange | |
379 | doesn't rely on ssh keys to verify host identity. | |
380 | The default is | |
381 | .Dq no . | |
382 | Note that this option applies to protocol version 2 only. | |
0fff78ff | 383 | .It Cm GSSAPICleanupCredentials |
384 | Specifies whether to automatically destroy the user's credentials cache | |
385 | on logout. | |
386 | The default is | |
387 | .Dq yes . | |
388 | Note that this option applies to protocol version 2 only. | |
f97edba6 | 389 | .It Cm GSSAPIStrictAcceptorCheck |
390 | Determines whether to be strict about the identity of the GSSAPI acceptor | |
391 | a client authenticates against. If | |
392 | .Dq yes | |
393 | then the client must authenticate against the | |
394 | .Pa host | |
395 | service on the current hostname. If | |
396 | .Dq no | |
397 | then the client may authenticate against any service key stored in the | |
398 | machine's default store. This facility is provided to assist with operation | |
399 | on multi homed machines. | |
400 | The default is | |
401 | .Dq yes . | |
402 | Note that this option applies only to protocol version 2 GSSAPI connections, | |
403 | and setting it to | |
404 | .Dq no | |
405 | may only work with recent Kerberos GSSAPI libraries. | |
406 | .It Cm GSSAPIStoreCredentialsOnRekey | |
407 | Controls whether the user's GSSAPI credentials should be updated following a | |
408 | successful connection rekeying. This option can be used to accepted renewed | |
409 | or updated credentials from a compatible client. The default is | |
410 | .Dq no . | |
f5799ae1 | 411 | .It Cm HostbasedAuthentication |
412 | Specifies whether rhosts or /etc/hosts.equiv authentication together | |
413 | with successful public key client host authentication is allowed | |
9108f8d9 | 414 | (host-based authentication). |
f5799ae1 | 415 | This option is similar to |
416 | .Cm RhostsRSAAuthentication | |
417 | and applies to protocol version 2 only. | |
418 | The default is | |
419 | .Dq no . | |
9108f8d9 | 420 | .It Cm HostbasedUsesNameFromPacketOnly |
421 | Specifies whether or not the server will attempt to perform a reverse | |
422 | name lookup when matching the name in the | |
423 | .Pa ~/.shosts , | |
424 | .Pa ~/.rhosts , | |
425 | and | |
426 | .Pa /etc/hosts.equiv | |
427 | files during | |
428 | .Cm HostbasedAuthentication . | |
429 | A setting of | |
430 | .Dq yes | |
431 | means that | |
432 | .Xr sshd 8 | |
433 | uses the name supplied by the client rather than | |
434 | attempting to resolve the name from the TCP connection itself. | |
435 | The default is | |
436 | .Dq no . | |
f5799ae1 | 437 | .It Cm HostKey |
438 | Specifies a file containing a private host key | |
439 | used by SSH. | |
440 | The default is | |
441 | .Pa /etc/ssh/ssh_host_key | |
442 | for protocol version 1, and | |
443 | .Pa /etc/ssh/ssh_host_rsa_key | |
444 | and | |
445 | .Pa /etc/ssh/ssh_host_dsa_key | |
446 | for protocol version 2. | |
447 | Note that | |
9108f8d9 | 448 | .Xr sshd 8 |
f5799ae1 | 449 | will refuse to use a file if it is group/world-accessible. |
450 | It is possible to have multiple host key files. | |
451 | .Dq rsa1 | |
452 | keys are used for version 1 and | |
453 | .Dq dsa | |
454 | or | |
455 | .Dq rsa | |
456 | are used for version 2 of the SSH protocol. | |
457 | .It Cm IgnoreRhosts | |
458 | Specifies that | |
459 | .Pa .rhosts | |
460 | and | |
461 | .Pa .shosts | |
462 | files will not be used in | |
f5799ae1 | 463 | .Cm RhostsRSAAuthentication |
464 | or | |
465 | .Cm HostbasedAuthentication . | |
466 | .Pp | |
467 | .Pa /etc/hosts.equiv | |
468 | and | |
469 | .Pa /etc/shosts.equiv | |
470 | are still used. | |
471 | The default is | |
472 | .Dq yes . | |
473 | .It Cm IgnoreUserKnownHosts | |
474 | Specifies whether | |
9108f8d9 | 475 | .Xr sshd 8 |
f5799ae1 | 476 | should ignore the user's |
665a873d | 477 | .Pa ~/.ssh/known_hosts |
f5799ae1 | 478 | during |
479 | .Cm RhostsRSAAuthentication | |
480 | or | |
481 | .Cm HostbasedAuthentication . | |
482 | The default is | |
483 | .Dq no . | |
f5799ae1 | 484 | .It Cm KerberosAuthentication |
0fff78ff | 485 | Specifies whether the password provided by the user for |
f5799ae1 | 486 | .Cm PasswordAuthentication |
0fff78ff | 487 | will be validated through the Kerberos KDC. |
f5799ae1 | 488 | To use this option, the server needs a |
489 | Kerberos servtab which allows the verification of the KDC's identity. | |
9108f8d9 | 490 | The default is |
f5799ae1 | 491 | .Dq no . |
99be0775 | 492 | .It Cm KerberosGetAFSToken |
2c06c99b | 493 | If AFS is active and the user has a Kerberos 5 TGT, attempt to acquire |
99be0775 | 494 | an AFS token before accessing the user's home directory. |
9108f8d9 | 495 | The default is |
99be0775 | 496 | .Dq no . |
f5799ae1 | 497 | .It Cm KerberosOrLocalPasswd |
9108f8d9 | 498 | If password authentication through Kerberos fails then |
f5799ae1 | 499 | the password will be validated via any additional local mechanism |
500 | such as | |
501 | .Pa /etc/passwd . | |
9108f8d9 | 502 | The default is |
f5799ae1 | 503 | .Dq yes . |
f5799ae1 | 504 | .It Cm KerberosTicketCleanup |
505 | Specifies whether to automatically destroy the user's ticket cache | |
506 | file on logout. | |
9108f8d9 | 507 | The default is |
f5799ae1 | 508 | .Dq yes . |
509 | .It Cm KeyRegenerationInterval | |
510 | In protocol version 1, the ephemeral server key is automatically regenerated | |
511 | after this many seconds (if it has been used). | |
512 | The purpose of regeneration is to prevent | |
513 | decrypting captured sessions by later breaking into the machine and | |
514 | stealing the keys. | |
515 | The key is never stored anywhere. | |
516 | If the value is 0, the key is never regenerated. | |
517 | The default is 3600 (seconds). | |
518 | .It Cm ListenAddress | |
519 | Specifies the local addresses | |
9108f8d9 | 520 | .Xr sshd 8 |
f5799ae1 | 521 | should listen on. |
522 | The following forms may be used: | |
523 | .Pp | |
524 | .Bl -item -offset indent -compact | |
525 | .It | |
526 | .Cm ListenAddress | |
527 | .Sm off | |
528 | .Ar host No | Ar IPv4_addr No | Ar IPv6_addr | |
529 | .Sm on | |
530 | .It | |
531 | .Cm ListenAddress | |
532 | .Sm off | |
533 | .Ar host No | Ar IPv4_addr No : Ar port | |
534 | .Sm on | |
535 | .It | |
536 | .Cm ListenAddress | |
537 | .Sm off | |
538 | .Oo | |
539 | .Ar host No | Ar IPv6_addr Oc : Ar port | |
540 | .Sm on | |
541 | .El | |
542 | .Pp | |
543 | If | |
544 | .Ar port | |
545 | is not specified, | |
9108f8d9 | 546 | sshd will listen on the address and all prior |
f5799ae1 | 547 | .Cm Port |
0fff78ff | 548 | options specified. |
549 | The default is to listen on all local addresses. | |
6a9b3198 | 550 | Multiple |
f5799ae1 | 551 | .Cm ListenAddress |
0fff78ff | 552 | options are permitted. |
553 | Additionally, any | |
f5799ae1 | 554 | .Cm Port |
9108f8d9 | 555 | options must precede this option for non-port qualified addresses. |
f5799ae1 | 556 | .It Cm LoginGraceTime |
557 | The server disconnects after this time if the user has not | |
558 | successfully logged in. | |
559 | If the value is 0, there is no time limit. | |
41b2f314 | 560 | The default is 120 seconds. |
f5799ae1 | 561 | .It Cm LogLevel |
562 | Gives the verbosity level that is used when logging messages from | |
9108f8d9 | 563 | .Xr sshd 8 . |
f5799ae1 | 564 | The possible values are: |
9108f8d9 | 565 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
6a9b3198 | 566 | The default is INFO. |
567 | DEBUG and DEBUG1 are equivalent. | |
568 | DEBUG2 and DEBUG3 each specify higher levels of debugging output. | |
569 | Logging with a DEBUG level violates the privacy of users and is not recommended. | |
f5799ae1 | 570 | .It Cm MACs |
571 | Specifies the available MAC (message authentication code) algorithms. | |
572 | The MAC algorithm is used in protocol version 2 | |
573 | for data integrity protection. | |
574 | Multiple algorithms must be comma-separated. | |
9108f8d9 | 575 | The default is: |
d4487008 | 576 | .Bd -literal -offset indent |
577 | hmac-md5,hmac-sha1,umac-64@openssh.com, | |
578 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 | |
579 | .Ed | |
9108f8d9 | 580 | .It Cm Match |
581 | Introduces a conditional block. | |
582 | If all of the criteria on the | |
583 | .Cm Match | |
584 | line are satisfied, the keywords on the following lines override those | |
585 | set in the global section of the config file, until either another | |
586 | .Cm Match | |
587 | line or the end of the file. | |
22616013 | 588 | .Pp |
9108f8d9 | 589 | The arguments to |
590 | .Cm Match | |
591 | are one or more criteria-pattern pairs. | |
592 | The available criteria are | |
593 | .Cm User , | |
594 | .Cm Group , | |
595 | .Cm Host , | |
596 | and | |
597 | .Cm Address . | |
22616013 | 598 | The match patterns may consist of single entries or comma-separated |
599 | lists and may use the wildcard and negation operators described in the | |
600 | .Sx PATTERNS | |
601 | section of | |
602 | .Xr ssh_config 5 . | |
603 | .Pp | |
604 | The patterns in an | |
605 | .Cm Address | |
606 | criteria may additionally contain addresses to match in CIDR | |
607 | address/masklen format, e.g.\& | |
608 | .Dq 192.0.2.0/24 | |
609 | or | |
610 | .Dq 3ffe:ffff::/32 . | |
611 | Note that the mask length provided must be consistent with the address - | |
612 | it is an error to specify a mask length that is too long for the address | |
613 | or one with bits set in this host portion of the address. | |
614 | For example, | |
615 | .Dq 192.0.2.0/33 | |
616 | and | |
617 | .Dq 192.0.2.0/8 | |
618 | respectively. | |
619 | .Pp | |
9108f8d9 | 620 | Only a subset of keywords may be used on the lines following a |
621 | .Cm Match | |
622 | keyword. | |
623 | Available keywords are | |
91d9cdd3 | 624 | .Cm AllowAgentForwarding , |
9108f8d9 | 625 | .Cm AllowTcpForwarding , |
799ae497 | 626 | .Cm Banner , |
22616013 | 627 | .Cm ChrootDirectory , |
9108f8d9 | 628 | .Cm ForceCommand , |
629 | .Cm GatewayPorts , | |
22616013 | 630 | .Cm GSSAPIAuthentication , |
631 | .Cm HostbasedAuthentication , | |
799ae497 | 632 | .Cm KbdInteractiveAuthentication , |
633 | .Cm KerberosAuthentication , | |
22616013 | 634 | .Cm MaxAuthTries , |
635 | .Cm MaxSessions , | |
799ae497 | 636 | .Cm PasswordAuthentication , |
91d9cdd3 | 637 | .Cm PermitEmptyPasswords , |
9108f8d9 | 638 | .Cm PermitOpen , |
47686178 | 639 | .Cm PermitRootLogin , |
799ae497 | 640 | .Cm RhostsRSAAuthentication , |
641 | .Cm RSAAuthentication , | |
9108f8d9 | 642 | .Cm X11DisplayOffset , |
91d9cdd3 | 643 | .Cm X11Forwarding |
9108f8d9 | 644 | and |
645 | .Cm X11UseLocalHost . | |
c9f39d2c | 646 | .It Cm MaxAuthTries |
647 | Specifies the maximum number of authentication attempts permitted per | |
648 | connection. | |
649 | Once the number of failures reaches half this value, | |
650 | additional failures are logged. | |
651 | The default is 6. | |
22616013 | 652 | .It Cm MaxSessions |
653 | Specifies the maximum number of open sessions permitted per network connection. | |
654 | The default is 10. | |
f5799ae1 | 655 | .It Cm MaxStartups |
656 | Specifies the maximum number of concurrent unauthenticated connections to the | |
9108f8d9 | 657 | SSH daemon. |
f5799ae1 | 658 | Additional connections will be dropped until authentication succeeds or the |
659 | .Cm LoginGraceTime | |
660 | expires for a connection. | |
661 | The default is 10. | |
662 | .Pp | |
663 | Alternatively, random early drop can be enabled by specifying | |
664 | the three colon separated values | |
665 | .Dq start:rate:full | |
9108f8d9 | 666 | (e.g. "10:30:60"). |
667 | .Xr sshd 8 | |
f5799ae1 | 668 | will refuse connection attempts with a probability of |
669 | .Dq rate/100 | |
670 | (30%) | |
671 | if there are currently | |
672 | .Dq start | |
673 | (10) | |
674 | unauthenticated connections. | |
675 | The probability increases linearly and all connection attempts | |
676 | are refused if the number of unauthenticated connections reaches | |
677 | .Dq full | |
678 | (60). | |
679 | .It Cm PasswordAuthentication | |
680 | Specifies whether password authentication is allowed. | |
681 | The default is | |
682 | .Dq yes . | |
683 | .It Cm PermitEmptyPasswords | |
684 | When password authentication is allowed, it specifies whether the | |
685 | server allows login to accounts with empty password strings. | |
686 | The default is | |
687 | .Dq no . | |
9108f8d9 | 688 | .It Cm PermitOpen |
689 | Specifies the destinations to which TCP port forwarding is permitted. | |
690 | The forwarding specification must be one of the following forms: | |
691 | .Pp | |
692 | .Bl -item -offset indent -compact | |
693 | .It | |
694 | .Cm PermitOpen | |
695 | .Sm off | |
696 | .Ar host : port | |
697 | .Sm on | |
698 | .It | |
699 | .Cm PermitOpen | |
700 | .Sm off | |
701 | .Ar IPv4_addr : port | |
702 | .Sm on | |
703 | .It | |
704 | .Cm PermitOpen | |
705 | .Sm off | |
706 | .Ar \&[ IPv6_addr \&] : port | |
707 | .Sm on | |
708 | .El | |
709 | .Pp | |
710 | Multiple forwards may be specified by separating them with whitespace. | |
711 | An argument of | |
712 | .Dq any | |
713 | can be used to remove all restrictions and permit any forwarding requests. | |
714 | By default all port forwarding requests are permitted. | |
f5799ae1 | 715 | .It Cm PermitRootLogin |
996d5e62 | 716 | Specifies whether root can log in using |
f5799ae1 | 717 | .Xr ssh 1 . |
718 | The argument must be | |
719 | .Dq yes , | |
720 | .Dq without-password , | |
9108f8d9 | 721 | .Dq forced-commands-only , |
f5799ae1 | 722 | or |
723 | .Dq no . | |
724 | The default is | |
725 | .Dq yes . | |
726 | .Pp | |
727 | If this option is set to | |
9108f8d9 | 728 | .Dq without-password , |
996d5e62 | 729 | password authentication is disabled for root. |
f5799ae1 | 730 | .Pp |
731 | If this option is set to | |
9108f8d9 | 732 | .Dq forced-commands-only , |
f5799ae1 | 733 | root login with public key authentication will be allowed, |
734 | but only if the | |
735 | .Ar command | |
736 | option has been specified | |
737 | (which may be useful for taking remote backups even if root login is | |
0fff78ff | 738 | normally not allowed). |
739 | All other authentication methods are disabled for root. | |
f5799ae1 | 740 | .Pp |
741 | If this option is set to | |
9108f8d9 | 742 | .Dq no , |
996d5e62 | 743 | root is not allowed to log in. |
2c06c99b | 744 | .It Cm PermitTunnel |
745 | Specifies whether | |
746 | .Xr tun 4 | |
747 | device forwarding is allowed. | |
748 | The argument must be | |
749 | .Dq yes , | |
9108f8d9 | 750 | .Dq point-to-point |
751 | (layer 3), | |
2c06c99b | 752 | .Dq ethernet |
9108f8d9 | 753 | (layer 2), or |
2c06c99b | 754 | .Dq no . |
9108f8d9 | 755 | Specifying |
756 | .Dq yes | |
757 | permits both | |
758 | .Dq point-to-point | |
759 | and | |
760 | .Dq ethernet . | |
2c06c99b | 761 | The default is |
762 | .Dq no . | |
41b2f314 | 763 | .It Cm PermitUserEnvironment |
764 | Specifies whether | |
765 | .Pa ~/.ssh/environment | |
766 | and | |
767 | .Cm environment= | |
768 | options in | |
769 | .Pa ~/.ssh/authorized_keys | |
770 | are processed by | |
9108f8d9 | 771 | .Xr sshd 8 . |
41b2f314 | 772 | The default is |
773 | .Dq no . | |
774 | Enabling environment processing may enable users to bypass access | |
775 | restrictions in some configurations using mechanisms such as | |
776 | .Ev LD_PRELOAD . | |
f5799ae1 | 777 | .It Cm PidFile |
680cee3b | 778 | Specifies the file that contains the process ID of the |
9108f8d9 | 779 | SSH daemon. |
f5799ae1 | 780 | The default is |
781 | .Pa /var/run/sshd.pid . | |
782 | .It Cm Port | |
783 | Specifies the port number that | |
9108f8d9 | 784 | .Xr sshd 8 |
f5799ae1 | 785 | listens on. |
786 | The default is 22. | |
787 | Multiple options of this type are permitted. | |
788 | See also | |
789 | .Cm ListenAddress . | |
790 | .It Cm PrintLastLog | |
791 | Specifies whether | |
9108f8d9 | 792 | .Xr sshd 8 |
996d5e62 | 793 | should print the date and time of the last user login when a user logs |
794 | in interactively. | |
f5799ae1 | 795 | The default is |
796 | .Dq yes . | |
797 | .It Cm PrintMotd | |
798 | Specifies whether | |
9108f8d9 | 799 | .Xr sshd 8 |
f5799ae1 | 800 | should print |
801 | .Pa /etc/motd | |
802 | when a user logs in interactively. | |
803 | (On some systems it is also printed by the shell, | |
804 | .Pa /etc/profile , | |
805 | or equivalent.) | |
806 | The default is | |
807 | .Dq yes . | |
808 | .It Cm Protocol | |
809 | Specifies the protocol versions | |
9108f8d9 | 810 | .Xr sshd 8 |
41b2f314 | 811 | supports. |
f5799ae1 | 812 | The possible values are |
9108f8d9 | 813 | .Sq 1 |
f5799ae1 | 814 | and |
9108f8d9 | 815 | .Sq 2 . |
f5799ae1 | 816 | Multiple versions must be comma-separated. |
817 | The default is | |
818 | .Dq 2,1 . | |
41b2f314 | 819 | Note that the order of the protocol list does not indicate preference, |
820 | because the client selects among multiple protocol versions offered | |
821 | by the server. | |
822 | Specifying | |
823 | .Dq 2,1 | |
824 | is identical to | |
825 | .Dq 1,2 . | |
f5799ae1 | 826 | .It Cm PubkeyAuthentication |
827 | Specifies whether public key authentication is allowed. | |
828 | The default is | |
829 | .Dq yes . | |
830 | Note that this option applies to protocol version 2 only. | |
f5799ae1 | 831 | .It Cm RhostsRSAAuthentication |
832 | Specifies whether rhosts or /etc/hosts.equiv authentication together | |
833 | with successful RSA host authentication is allowed. | |
834 | The default is | |
835 | .Dq no . | |
836 | This option applies to protocol version 1 only. | |
837 | .It Cm RSAAuthentication | |
838 | Specifies whether pure RSA authentication is allowed. | |
839 | The default is | |
840 | .Dq yes . | |
841 | This option applies to protocol version 1 only. | |
842 | .It Cm ServerKeyBits | |
843 | Defines the number of bits in the ephemeral protocol version 1 server key. | |
22616013 | 844 | The minimum value is 512, and the default is 1024. |
f5799ae1 | 845 | .It Cm StrictModes |
846 | Specifies whether | |
9108f8d9 | 847 | .Xr sshd 8 |
f5799ae1 | 848 | should check file modes and ownership of the |
849 | user's files and home directory before accepting login. | |
850 | This is normally desirable because novices sometimes accidentally leave their | |
851 | directory or files world-writable. | |
852 | The default is | |
853 | .Dq yes . | |
854 | .It Cm Subsystem | |
9108f8d9 | 855 | Configures an external subsystem (e.g. file transfer daemon). |
856 | Arguments should be a subsystem name and a command (with optional arguments) | |
857 | to execute upon subsystem request. | |
47686178 | 858 | .Pp |
f5799ae1 | 859 | The command |
860 | .Xr sftp-server 8 | |
861 | implements the | |
862 | .Dq sftp | |
863 | file transfer subsystem. | |
47686178 | 864 | .Pp |
865 | Alternately the name | |
866 | .Dq internal-sftp | |
867 | implements an in-process | |
868 | .Dq sftp | |
869 | server. | |
870 | This may simplify configurations using | |
871 | .Cm ChrootDirectory | |
872 | to force a different filesystem root on clients. | |
873 | .Pp | |
f5799ae1 | 874 | By default no subsystems are defined. |
875 | Note that this option applies to protocol version 2 only. | |
876 | .It Cm SyslogFacility | |
877 | Gives the facility code that is used when logging messages from | |
9108f8d9 | 878 | .Xr sshd 8 . |
f5799ae1 | 879 | The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, |
880 | LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. | |
881 | The default is AUTH. | |
cdd66111 | 882 | .It Cm TCPKeepAlive |
883 | Specifies whether the system should send TCP keepalive messages to the | |
884 | other side. | |
885 | If they are sent, death of the connection or crash of one | |
886 | of the machines will be properly noticed. | |
887 | However, this means that | |
888 | connections will die if the route is down temporarily, and some people | |
889 | find it annoying. | |
890 | On the other hand, if TCP keepalives are not sent, | |
891 | sessions may hang indefinitely on the server, leaving | |
892 | .Dq ghost | |
893 | users and consuming server resources. | |
894 | .Pp | |
895 | The default is | |
896 | .Dq yes | |
897 | (to send TCP keepalive messages), and the server will notice | |
898 | if the network goes down or the client host crashes. | |
899 | This avoids infinitely hanging sessions. | |
900 | .Pp | |
901 | To disable TCP keepalive messages, the value should be set to | |
902 | .Dq no . | |
0fff78ff | 903 | .It Cm UseDNS |
904 | Specifies whether | |
9108f8d9 | 905 | .Xr sshd 8 |
dec6d9fe | 906 | should look up the remote host name and check that |
0fff78ff | 907 | the resolved host name for the remote IP address maps back to the |
908 | very same IP address. | |
909 | The default is | |
910 | .Dq yes . | |
f5799ae1 | 911 | .It Cm UseLogin |
912 | Specifies whether | |
913 | .Xr login 1 | |
914 | is used for interactive login sessions. | |
915 | The default is | |
916 | .Dq no . | |
917 | Note that | |
918 | .Xr login 1 | |
919 | is never used for remote command execution. | |
920 | Note also, that if this is enabled, | |
921 | .Cm X11Forwarding | |
922 | will be disabled because | |
923 | .Xr login 1 | |
924 | does not know how to handle | |
925 | .Xr xauth 1 | |
6a9b3198 | 926 | cookies. |
927 | If | |
f5799ae1 | 928 | .Cm UsePrivilegeSeparation |
929 | is specified, it will be disabled after authentication. | |
0fff78ff | 930 | .It Cm UsePAM |
c9f39d2c | 931 | Enables the Pluggable Authentication Module interface. |
932 | If set to | |
933 | .Dq yes | |
934 | this will enable PAM authentication using | |
935 | .Cm ChallengeResponseAuthentication | |
9108f8d9 | 936 | and |
937 | .Cm PasswordAuthentication | |
938 | in addition to PAM account and session module processing for all | |
939 | authentication types. | |
c9f39d2c | 940 | .Pp |
941 | Because PAM challenge-response authentication usually serves an equivalent | |
942 | role to password authentication, you should disable either | |
943 | .Cm PasswordAuthentication | |
944 | or | |
945 | .Cm ChallengeResponseAuthentication. | |
946 | .Pp | |
947 | If | |
948 | .Cm UsePAM | |
949 | is enabled, you will not be able to run | |
950 | .Xr sshd 8 | |
951 | as a non-root user. | |
952 | The default is | |
cdd66111 | 953 | .Dq no . |
f5799ae1 | 954 | .It Cm UsePrivilegeSeparation |
955 | Specifies whether | |
9108f8d9 | 956 | .Xr sshd 8 |
f5799ae1 | 957 | separates privileges by creating an unprivileged child process |
6a9b3198 | 958 | to deal with incoming network traffic. |
959 | After successful authentication, another process will be created that has | |
960 | the privilege of the authenticated user. | |
961 | The goal of privilege separation is to prevent privilege | |
f5799ae1 | 962 | escalation by containing any corruption within the unprivileged processes. |
963 | The default is | |
964 | .Dq yes . | |
f5799ae1 | 965 | .It Cm X11DisplayOffset |
966 | Specifies the first display number available for | |
9108f8d9 | 967 | .Xr sshd 8 Ns 's |
f5799ae1 | 968 | X11 forwarding. |
9108f8d9 | 969 | This prevents sshd from interfering with real X11 servers. |
f5799ae1 | 970 | The default is 10. |
971 | .It Cm X11Forwarding | |
972 | Specifies whether X11 forwarding is permitted. | |
41b2f314 | 973 | The argument must be |
974 | .Dq yes | |
975 | or | |
976 | .Dq no . | |
f5799ae1 | 977 | The default is |
978 | .Dq no . | |
41b2f314 | 979 | .Pp |
980 | When X11 forwarding is enabled, there may be additional exposure to | |
981 | the server and to client displays if the | |
9108f8d9 | 982 | .Xr sshd 8 |
41b2f314 | 983 | proxy display is configured to listen on the wildcard address (see |
984 | .Cm X11UseLocalhost | |
9108f8d9 | 985 | below), though this is not the default. |
41b2f314 | 986 | Additionally, the authentication spoofing and authentication data |
987 | verification and substitution occur on the client side. | |
988 | The security risk of using X11 forwarding is that the client's X11 | |
9108f8d9 | 989 | display server may be exposed to attack when the SSH client requests |
41b2f314 | 990 | forwarding (see the warnings for |
991 | .Cm ForwardX11 | |
992 | in | |
0fff78ff | 993 | .Xr ssh_config 5 ) . |
41b2f314 | 994 | A system administrator may have a stance in which they want to |
995 | protect clients that may expose themselves to attack by unwittingly | |
996 | requesting X11 forwarding, which can warrant a | |
997 | .Dq no | |
998 | setting. | |
999 | .Pp | |
1000 | Note that disabling X11 forwarding does not prevent users from | |
1001 | forwarding X11 traffic, as users can always install their own forwarders. | |
f5799ae1 | 1002 | X11 forwarding is automatically disabled if |
1003 | .Cm UseLogin | |
1004 | is enabled. | |
1005 | .It Cm X11UseLocalhost | |
1006 | Specifies whether | |
9108f8d9 | 1007 | .Xr sshd 8 |
f5799ae1 | 1008 | should bind the X11 forwarding server to the loopback address or to |
6a9b3198 | 1009 | the wildcard address. |
1010 | By default, | |
9108f8d9 | 1011 | sshd binds the forwarding server to the loopback address and sets the |
f5799ae1 | 1012 | hostname part of the |
1013 | .Ev DISPLAY | |
1014 | environment variable to | |
1015 | .Dq localhost . | |
41b2f314 | 1016 | This prevents remote hosts from connecting to the proxy display. |
f5799ae1 | 1017 | However, some older X11 clients may not function with this |
1018 | configuration. | |
1019 | .Cm X11UseLocalhost | |
1020 | may be set to | |
1021 | .Dq no | |
1022 | to specify that the forwarding server should be bound to the wildcard | |
1023 | address. | |
1024 | The argument must be | |
1025 | .Dq yes | |
1026 | or | |
1027 | .Dq no . | |
1028 | The default is | |
1029 | .Dq yes . | |
1030 | .It Cm XAuthLocation | |
41b2f314 | 1031 | Specifies the full pathname of the |
f5799ae1 | 1032 | .Xr xauth 1 |
1033 | program. | |
1034 | The default is | |
1035 | .Pa /usr/X11R6/bin/xauth . | |
1036 | .El | |
9108f8d9 | 1037 | .Sh TIME FORMATS |
1038 | .Xr sshd 8 | |
f5799ae1 | 1039 | command-line arguments and configuration file options that specify time |
1040 | may be expressed using a sequence of the form: | |
1041 | .Sm off | |
41b2f314 | 1042 | .Ar time Op Ar qualifier , |
f5799ae1 | 1043 | .Sm on |
1044 | where | |
1045 | .Ar time | |
1046 | is a positive integer value and | |
1047 | .Ar qualifier | |
1048 | is one of the following: | |
1049 | .Pp | |
1050 | .Bl -tag -width Ds -compact -offset indent | |
9108f8d9 | 1051 | .It Aq Cm none |
f5799ae1 | 1052 | seconds |
1053 | .It Cm s | Cm S | |
1054 | seconds | |
1055 | .It Cm m | Cm M | |
1056 | minutes | |
1057 | .It Cm h | Cm H | |
1058 | hours | |
1059 | .It Cm d | Cm D | |
1060 | days | |
1061 | .It Cm w | Cm W | |
1062 | weeks | |
1063 | .El | |
1064 | .Pp | |
1065 | Each member of the sequence is added together to calculate | |
1066 | the total time value. | |
1067 | .Pp | |
1068 | Time format examples: | |
1069 | .Pp | |
1070 | .Bl -tag -width Ds -compact -offset indent | |
1071 | .It 600 | |
1072 | 600 seconds (10 minutes) | |
1073 | .It 10m | |
1074 | 10 minutes | |
1075 | .It 1h30m | |
1076 | 1 hour 30 minutes (90 minutes) | |
1077 | .El | |
1078 | .Sh FILES | |
1079 | .Bl -tag -width Ds | |
1080 | .It Pa /etc/ssh/sshd_config | |
1081 | Contains configuration data for | |
9108f8d9 | 1082 | .Xr sshd 8 . |
f5799ae1 | 1083 | This file should be writable by root only, but it is recommended |
1084 | (though not necessary) that it be world-readable. | |
1085 | .El | |
0fff78ff | 1086 | .Sh SEE ALSO |
1087 | .Xr sshd 8 | |
f5799ae1 | 1088 | .Sh AUTHORS |
1089 | OpenSSH is a derivative of the original and free | |
1090 | ssh 1.2.12 release by Tatu Ylonen. | |
1091 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
1092 | Theo de Raadt and Dug Song | |
1093 | removed many bugs, re-added newer features and | |
1094 | created OpenSSH. | |
1095 | Markus Friedl contributed the support for SSH | |
1096 | protocol versions 1.5 and 2.0. | |
1097 | Niels Provos and Markus Friedl contributed support | |
1098 | for privilege separation. |