Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 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 | .\" |
Damien Miller | 5059d8d | 2010-03-05 21:31:11 +1100 | [diff] [blame] | 37 | .\" $OpenBSD: ssh_config.5,v 1.129 2010/03/05 10:28:21 djm Exp $ |
| 38 | .Dd $Mdocdate: March 5 2010 $ |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 39 | .Dt SSH_CONFIG 5 |
| 40 | .Os |
| 41 | .Sh NAME |
| 42 | .Nm ssh_config |
| 43 | .Nd OpenSSH SSH client configuration files |
| 44 | .Sh SYNOPSIS |
Darren Tucker | bf6b328 | 2007-02-19 22:08:17 +1100 | [diff] [blame] | 45 | .Nm ~/.ssh/config |
| 46 | .Nm /etc/ssh/ssh_config |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 47 | .Sh DESCRIPTION |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 48 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 49 | obtains configuration data from the following sources in |
| 50 | the following order: |
Damien Miller | 5c853b5 | 2006-03-15 11:37:02 +1100 | [diff] [blame] | 51 | .Pp |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 52 | .Bl -enum -offset indent -compact |
| 53 | .It |
| 54 | command-line options |
| 55 | .It |
| 56 | user's configuration file |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 57 | .Pq Pa ~/.ssh/config |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 58 | .It |
| 59 | system-wide configuration file |
| 60 | .Pq Pa /etc/ssh/ssh_config |
| 61 | .El |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 62 | .Pp |
| 63 | For each parameter, the first obtained value |
| 64 | will be used. |
Darren Tucker | 43d8e28 | 2005-02-09 09:51:08 +1100 | [diff] [blame] | 65 | The configuration files contain sections separated by |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 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. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 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 , |
Damien Miller | 4aea974 | 2006-03-15 11:59:39 +1100 | [diff] [blame] | 88 | .Nm scp , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 89 | and |
| 90 | .Nm sftp |
| 91 | .Fl o |
| 92 | option. |
Damien Miller | 306d118 | 2006-03-15 12:05:59 +1100 | [diff] [blame] | 93 | Arguments may optionally be enclosed in double quotes |
| 94 | .Pq \&" |
| 95 | in order to represent arguments containing spaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 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. |
Damien Miller | fa51b16 | 2008-11-03 19:17:33 +1100 | [diff] [blame] | 106 | If more than one pattern is provided, they should be separated by whitespace. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 107 | A single |
Damien Miller | 208f1ed | 2006-03-15 11:56:03 +1100 | [diff] [blame] | 108 | .Ql * |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 109 | as a pattern can be used to provide global |
| 110 | defaults for all hosts. |
| 111 | The host is the |
| 112 | .Ar hostname |
Damien Miller | 208f1ed | 2006-03-15 11:56:03 +1100 | [diff] [blame] | 113 | argument given on the command line (i.e. the name is not converted to |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 114 | a canonicalized host name before matching). |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 115 | .Pp |
| 116 | See |
| 117 | .Sx PATTERNS |
| 118 | for more information on patterns. |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 119 | .It Cm AddressFamily |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 120 | Specifies which address family to use when connecting. |
| 121 | Valid arguments are |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 122 | .Dq any , |
| 123 | .Dq inet |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 124 | (use IPv4 only), or |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 125 | .Dq inet6 |
Darren Tucker | 79a7acf | 2005-02-09 09:48:57 +1100 | [diff] [blame] | 126 | (use IPv6 only). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 127 | .It Cm BatchMode |
| 128 | If set to |
| 129 | .Dq yes , |
| 130 | passphrase/password querying will be disabled. |
| 131 | This option is useful in scripts and other batch jobs where no user |
| 132 | is present to supply the password. |
| 133 | The argument must be |
| 134 | .Dq yes |
| 135 | or |
| 136 | .Dq no . |
| 137 | The default is |
| 138 | .Dq no . |
| 139 | .It Cm BindAddress |
Darren Tucker | 89f4d47 | 2005-07-14 17:06:21 +1000 | [diff] [blame] | 140 | Use the specified address on the local machine as the source address of |
Darren Tucker | 6c71d20 | 2005-07-14 17:06:50 +1000 | [diff] [blame] | 141 | the connection. |
| 142 | Only useful on systems with more than one address. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 143 | Note that this option does not work if |
| 144 | .Cm UsePrivilegedPort |
| 145 | is set to |
| 146 | .Dq yes . |
| 147 | .It Cm ChallengeResponseAuthentication |
Damien Miller | 1faa713 | 2006-03-15 11:55:31 +1100 | [diff] [blame] | 148 | Specifies whether to use challenge-response authentication. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 149 | The argument to this keyword must be |
| 150 | .Dq yes |
| 151 | or |
| 152 | .Dq no . |
| 153 | The default is |
| 154 | .Dq yes . |
| 155 | .It Cm CheckHostIP |
| 156 | If this flag is set to |
| 157 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 158 | .Xr ssh 1 |
| 159 | will additionally check the host IP address in the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 160 | .Pa known_hosts |
| 161 | file. |
| 162 | This allows ssh to detect if a host key changed due to DNS spoofing. |
| 163 | If the option is set to |
| 164 | .Dq no , |
| 165 | the check will not be executed. |
| 166 | The default is |
| 167 | .Dq yes . |
| 168 | .It Cm Cipher |
| 169 | Specifies the cipher to use for encrypting the session |
| 170 | in protocol version 1. |
| 171 | Currently, |
| 172 | .Dq blowfish , |
| 173 | .Dq 3des , |
| 174 | and |
| 175 | .Dq des |
| 176 | are supported. |
| 177 | .Ar des |
| 178 | is only supported in the |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 179 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 180 | client for interoperability with legacy protocol 1 implementations |
| 181 | that do not support the |
| 182 | .Ar 3des |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 183 | cipher. |
| 184 | Its use is strongly discouraged due to cryptographic weaknesses. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 185 | The default is |
| 186 | .Dq 3des . |
| 187 | .It Cm Ciphers |
| 188 | Specifies the ciphers allowed for protocol version 2 |
| 189 | in order of preference. |
| 190 | Multiple ciphers must be comma-separated. |
Damien Miller | 05202ff | 2004-06-15 10:30:39 +1000 | [diff] [blame] | 191 | The supported ciphers are |
| 192 | .Dq 3des-cbc , |
| 193 | .Dq aes128-cbc , |
| 194 | .Dq aes192-cbc , |
| 195 | .Dq aes256-cbc , |
| 196 | .Dq aes128-ctr , |
| 197 | .Dq aes192-ctr , |
| 198 | .Dq aes256-ctr , |
Damien Miller | 3710f27 | 2005-05-26 12:19:17 +1000 | [diff] [blame] | 199 | .Dq arcfour128 , |
| 200 | .Dq arcfour256 , |
Damien Miller | 05202ff | 2004-06-15 10:30:39 +1000 | [diff] [blame] | 201 | .Dq arcfour , |
| 202 | .Dq blowfish-cbc , |
| 203 | and |
| 204 | .Dq cast128-cbc . |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 205 | The default is: |
| 206 | .Bd -literal -offset 3n |
Damien Miller | 9aa72ba | 2009-01-28 16:34:00 +1100 | [diff] [blame] | 207 | aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128, |
| 208 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc, |
| 209 | aes256-cbc,arcfour |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 210 | .Ed |
| 211 | .It Cm ClearAllForwardings |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 212 | Specifies that all local, remote, and dynamic port forwardings |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 213 | specified in the configuration files or on the command line be |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 214 | cleared. |
| 215 | This option is primarily useful when used from the |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 216 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 217 | command line to clear port forwardings set in |
| 218 | configuration files, and is automatically set by |
| 219 | .Xr scp 1 |
| 220 | and |
| 221 | .Xr sftp 1 . |
| 222 | The argument must be |
| 223 | .Dq yes |
| 224 | or |
| 225 | .Dq no . |
| 226 | The default is |
| 227 | .Dq no . |
| 228 | .It Cm Compression |
| 229 | Specifies whether to use compression. |
| 230 | The argument must be |
| 231 | .Dq yes |
| 232 | or |
| 233 | .Dq no . |
| 234 | The default is |
| 235 | .Dq no . |
| 236 | .It Cm CompressionLevel |
| 237 | Specifies the compression level to use if compression is enabled. |
| 238 | The argument must be an integer from 1 (fast) to 9 (slow, best). |
| 239 | The default level is 6, which is good for most applications. |
| 240 | The meaning of the values is the same as in |
| 241 | .Xr gzip 1 . |
| 242 | Note that this option applies to protocol version 1 only. |
| 243 | .It Cm ConnectionAttempts |
| 244 | Specifies the number of tries (one per second) to make before exiting. |
| 245 | The argument must be an integer. |
| 246 | This may be useful in scripts if the connection sometimes fails. |
| 247 | The default is 1. |
Damien Miller | b78d5eb | 2003-05-16 11:39:04 +1000 | [diff] [blame] | 248 | .It Cm ConnectTimeout |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 249 | Specifies the timeout (in seconds) used when connecting to the |
| 250 | SSH server, instead of using the default system TCP timeout. |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 251 | This value is used only when the target is down or really unreachable, |
| 252 | not when it refuses the connection. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 253 | .It Cm ControlMaster |
| 254 | Enables the sharing of multiple sessions over a single network connection. |
| 255 | When set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 256 | .Dq yes , |
| 257 | .Xr ssh 1 |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 258 | will listen for connections on a control socket specified using the |
| 259 | .Cm ControlPath |
| 260 | argument. |
| 261 | Additional sessions can connect to this socket using the same |
| 262 | .Cm ControlPath |
| 263 | with |
| 264 | .Cm ControlMaster |
| 265 | set to |
| 266 | .Dq no |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 267 | (the default). |
Damien Miller | 713de76 | 2005-11-05 15:13:49 +1100 | [diff] [blame] | 268 | These sessions will try to reuse the master instance's network connection |
Damien Miller | b3bfbb7 | 2005-11-05 15:11:48 +1100 | [diff] [blame] | 269 | rather than initiating new ones, but will fall back to connecting normally |
| 270 | if the control socket does not exist, or is not listening. |
| 271 | .Pp |
Damien Miller | 23f0770 | 2004-06-18 01:19:03 +1000 | [diff] [blame] | 272 | Setting this to |
| 273 | .Dq ask |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 274 | will cause ssh |
Damien Miller | 23f0770 | 2004-06-18 01:19:03 +1000 | [diff] [blame] | 275 | to listen for control connections, but require confirmation using the |
| 276 | .Ev SSH_ASKPASS |
| 277 | program before they are accepted (see |
| 278 | .Xr ssh-add 1 |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 279 | for details). |
Damien Miller | dadfd4d | 2005-05-26 12:07:13 +1000 | [diff] [blame] | 280 | If the |
| 281 | .Cm ControlPath |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 282 | cannot be opened, |
| 283 | ssh will continue without connecting to a master instance. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 284 | .Pp |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 285 | X11 and |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 286 | .Xr ssh-agent 1 |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 287 | forwarding is supported over these multiplexed connections, however the |
Darren Tucker | 6355187 | 2005-12-20 16:14:15 +1100 | [diff] [blame] | 288 | display and agent forwarded will be the one belonging to the master |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 289 | connection i.e. it is not possible to forward multiple displays or agents. |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 290 | .Pp |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 291 | Two additional options allow for opportunistic multiplexing: try to use a |
| 292 | master connection but fall back to creating a new one if one does not already |
| 293 | exist. |
| 294 | These options are: |
| 295 | .Dq auto |
| 296 | and |
| 297 | .Dq autoask . |
| 298 | The latter requires confirmation like the |
| 299 | .Dq ask |
| 300 | option. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 301 | .It Cm ControlPath |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 302 | Specify the path to the control socket used for connection sharing as described |
| 303 | in the |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 304 | .Cm ControlMaster |
Damien Miller | 8f74c8f | 2005-06-26 08:56:03 +1000 | [diff] [blame] | 305 | section above or the string |
| 306 | .Dq none |
| 307 | to disable connection sharing. |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 308 | In the path, |
Damien Miller | 3ec54c7 | 2006-03-15 11:30:13 +1100 | [diff] [blame] | 309 | .Ql %l |
| 310 | will be substituted by the local host name, |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 311 | .Ql %h |
| 312 | will be substituted by the target host name, |
| 313 | .Ql %p |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 314 | the port, and |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 315 | .Ql %r |
| 316 | by the remote login username. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 317 | It is recommended that any |
| 318 | .Cm ControlPath |
| 319 | used for opportunistic connection sharing include |
Damien Miller | 20c2ec4 | 2006-03-15 11:31:01 +1100 | [diff] [blame] | 320 | at least %h, %p, and %r. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 321 | This ensures that shared connections are uniquely identified. |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 322 | .It Cm DynamicForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 323 | Specifies that a TCP port on the local machine be forwarded |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 324 | over the secure channel, and the application |
| 325 | protocol is then used to determine where to connect to from the |
| 326 | remote machine. |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 327 | .Pp |
| 328 | The argument must be |
| 329 | .Sm off |
| 330 | .Oo Ar bind_address : Oc Ar port . |
| 331 | .Sm on |
| 332 | IPv6 addresses can be specified by enclosing addresses in square brackets or |
| 333 | by using an alternative syntax: |
| 334 | .Oo Ar bind_address Ns / Oc Ns Ar port . |
| 335 | By default, the local port is bound in accordance with the |
| 336 | .Cm GatewayPorts |
| 337 | setting. |
| 338 | However, an explicit |
| 339 | .Ar bind_address |
| 340 | may be used to bind the connection to a specific address. |
| 341 | The |
| 342 | .Ar bind_address |
| 343 | of |
| 344 | .Dq localhost |
| 345 | indicates that the listening port be bound for local use only, while an |
| 346 | empty address or |
| 347 | .Sq * |
| 348 | indicates that the port should be available from all interfaces. |
| 349 | .Pp |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 350 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 351 | .Xr ssh 1 |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 352 | will act as a SOCKS server. |
| 353 | Multiple forwardings may be specified, and |
| 354 | additional forwardings can be given on the command line. |
| 355 | Only the superuser can forward privileged ports. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 356 | .It Cm EnableSSHKeysign |
| 357 | Setting this option to |
| 358 | .Dq yes |
| 359 | in the global client configuration file |
| 360 | .Pa /etc/ssh/ssh_config |
| 361 | enables the use of the helper program |
| 362 | .Xr ssh-keysign 8 |
| 363 | during |
| 364 | .Cm HostbasedAuthentication . |
| 365 | The argument must be |
| 366 | .Dq yes |
| 367 | or |
| 368 | .Dq no . |
| 369 | The default is |
| 370 | .Dq no . |
Darren Tucker | f132c67 | 2003-10-15 15:58:18 +1000 | [diff] [blame] | 371 | This option should be placed in the non-hostspecific section. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 372 | See |
| 373 | .Xr ssh-keysign 8 |
| 374 | for more information. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 375 | .It Cm EscapeChar |
| 376 | Sets the escape character (default: |
| 377 | .Ql ~ ) . |
| 378 | The escape character can also |
| 379 | be set on the command line. |
| 380 | The argument should be a single character, |
| 381 | .Ql ^ |
| 382 | followed by a letter, or |
| 383 | .Dq none |
| 384 | to disable the escape |
| 385 | character entirely (making the connection transparent for binary |
| 386 | data). |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 387 | .It Cm ExitOnForwardFailure |
| 388 | Specifies whether |
| 389 | .Xr ssh 1 |
| 390 | should terminate the connection if it cannot set up all requested |
Darren Tucker | fc5d188 | 2007-08-15 22:20:22 +1000 | [diff] [blame] | 391 | dynamic, tunnel, local, and remote port forwardings. |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 392 | The argument must be |
| 393 | .Dq yes |
| 394 | or |
| 395 | .Dq no . |
| 396 | The default is |
| 397 | .Dq no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 398 | .It Cm ForwardAgent |
| 399 | Specifies whether the connection to the authentication agent (if any) |
| 400 | will be forwarded to the remote machine. |
| 401 | The argument must be |
| 402 | .Dq yes |
| 403 | or |
| 404 | .Dq no . |
| 405 | The default is |
| 406 | .Dq no . |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 407 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 408 | Agent forwarding should be enabled with caution. |
| 409 | Users with the ability to bypass file permissions on the remote host |
| 410 | (for the agent's Unix-domain socket) |
| 411 | can access the local agent through the forwarded connection. |
| 412 | An attacker cannot obtain key material from the agent, |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 413 | however they can perform operations on the keys that enable them to |
| 414 | authenticate using the identities loaded into the agent. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 415 | .It Cm ForwardX11 |
| 416 | Specifies whether X11 connections will be automatically redirected |
| 417 | over the secure channel and |
| 418 | .Ev DISPLAY |
| 419 | set. |
| 420 | The argument must be |
| 421 | .Dq yes |
| 422 | or |
| 423 | .Dq no . |
| 424 | The default is |
| 425 | .Dq no . |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 426 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 427 | X11 forwarding should be enabled with caution. |
| 428 | Users with the ability to bypass file permissions on the remote host |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 429 | (for the user's X11 authorization database) |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 430 | can access the local X11 display through the forwarded connection. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 431 | An attacker may then be able to perform activities such as keystroke monitoring |
| 432 | if the |
| 433 | .Cm ForwardX11Trusted |
| 434 | option is also enabled. |
| 435 | .It Cm ForwardX11Trusted |
Darren Tucker | dcf6ec4 | 2004-05-13 13:03:56 +1000 | [diff] [blame] | 436 | If this option is set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 437 | .Dq yes , |
| 438 | remote X11 clients will have full access to the original X11 display. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 439 | .Pp |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 440 | If this option is set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 441 | .Dq no , |
| 442 | remote X11 clients will be considered untrusted and prevented |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 443 | from stealing or tampering with data belonging to trusted X11 |
| 444 | clients. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 445 | Furthermore, the |
| 446 | .Xr xauth 1 |
| 447 | token used for the session will be set to expire after 20 minutes. |
| 448 | Remote clients will be refused access after this time. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 449 | .Pp |
| 450 | The default is |
| 451 | .Dq no . |
| 452 | .Pp |
| 453 | See the X11 SECURITY extension specification for full details on |
| 454 | the restrictions imposed on untrusted clients. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 455 | .It Cm GatewayPorts |
| 456 | Specifies whether remote hosts are allowed to connect to local |
| 457 | forwarded ports. |
| 458 | By default, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 459 | .Xr ssh 1 |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 460 | binds local port forwardings to the loopback address. |
| 461 | This prevents other remote hosts from connecting to forwarded ports. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 462 | .Cm GatewayPorts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 463 | can be used to specify that ssh |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 464 | should bind local port forwardings to the wildcard address, |
| 465 | thus allowing remote hosts to connect to forwarded ports. |
| 466 | The argument must be |
| 467 | .Dq yes |
| 468 | or |
| 469 | .Dq no . |
| 470 | The default is |
| 471 | .Dq no . |
| 472 | .It Cm GlobalKnownHostsFile |
| 473 | Specifies a file to use for the global |
| 474 | host key database instead of |
| 475 | .Pa /etc/ssh/ssh_known_hosts . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 476 | .It Cm GSSAPIAuthentication |
Damien Miller | baafb98 | 2003-12-17 16:32:23 +1100 | [diff] [blame] | 477 | Specifies whether user authentication based on GSSAPI is allowed. |
Damien Miller | c2b9827 | 2003-09-03 12:13:30 +1000 | [diff] [blame] | 478 | The default is |
Darren Tucker | a044f47 | 2003-10-15 15:52:03 +1000 | [diff] [blame] | 479 | .Dq no . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 480 | Note that this option applies to protocol version 2 only. |
| 481 | .It Cm GSSAPIDelegateCredentials |
| 482 | Forward (delegate) credentials to the server. |
| 483 | The default is |
| 484 | .Dq no . |
| 485 | Note that this option applies to protocol version 2 only. |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 486 | .It Cm HashKnownHosts |
| 487 | Indicates that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 488 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 489 | should hash host names and addresses when they are added to |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 490 | .Pa ~/.ssh/known_hosts . |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 491 | These hashed names may be used normally by |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 492 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 493 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 494 | .Xr sshd 8 , |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 495 | but they do not reveal identifying information should the file's contents |
| 496 | be disclosed. |
| 497 | The default is |
| 498 | .Dq no . |
Damien Miller | 858bb7d | 2006-08-05 11:34:51 +1000 | [diff] [blame] | 499 | Note that existing names and addresses in known hosts files |
| 500 | will not be converted automatically, |
| 501 | but may be manually hashed using |
Damien Miller | 4b42d7f | 2005-03-01 21:48:35 +1100 | [diff] [blame] | 502 | .Xr ssh-keygen 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 503 | .It Cm HostbasedAuthentication |
| 504 | Specifies whether to try rhosts based authentication with public key |
| 505 | authentication. |
| 506 | The argument must be |
| 507 | .Dq yes |
| 508 | or |
| 509 | .Dq no . |
| 510 | The default is |
| 511 | .Dq no . |
| 512 | This option applies to protocol version 2 only and |
| 513 | is similar to |
| 514 | .Cm RhostsRSAAuthentication . |
| 515 | .It Cm HostKeyAlgorithms |
| 516 | Specifies the protocol version 2 host key algorithms |
| 517 | that the client wants to use in order of preference. |
| 518 | The default for this option is: |
| 519 | .Dq ssh-rsa,ssh-dss . |
| 520 | .It Cm HostKeyAlias |
| 521 | Specifies an alias that should be used instead of the |
| 522 | real host name when looking up or saving the host key |
| 523 | in the host key database files. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 524 | This option is useful for tunneling SSH connections |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 525 | or for multiple servers running on a single host. |
| 526 | .It Cm HostName |
| 527 | Specifies the real host name to log into. |
| 528 | This can be used to specify nicknames or abbreviations for hosts. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 529 | The default is the name given on the command line. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 530 | Numeric IP addresses are also permitted (both on the command line and in |
| 531 | .Cm HostName |
| 532 | specifications). |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 533 | .It Cm IdentitiesOnly |
| 534 | Specifies that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 535 | .Xr ssh 1 |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 536 | should only use the authentication identity files configured in the |
Damien Miller | 1a81258 | 2004-04-20 20:13:32 +1000 | [diff] [blame] | 537 | .Nm |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 538 | files, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 539 | even if |
| 540 | .Xr ssh-agent 1 |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 541 | offers more identities. |
| 542 | The argument to this keyword must be |
| 543 | .Dq yes |
| 544 | or |
| 545 | .Dq no . |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 546 | This option is intended for situations where ssh-agent |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 547 | offers many different identities. |
| 548 | The default is |
| 549 | .Dq no . |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 550 | .It Cm IdentityFile |
| 551 | Specifies a file from which the user's RSA or DSA authentication identity |
| 552 | is read. |
| 553 | The default is |
| 554 | .Pa ~/.ssh/identity |
| 555 | for protocol version 1, and |
| 556 | .Pa ~/.ssh/id_rsa |
| 557 | and |
| 558 | .Pa ~/.ssh/id_dsa |
| 559 | for protocol version 2. |
| 560 | Additionally, any identities represented by the authentication agent |
| 561 | will be used for authentication. |
Damien Miller | 5059d8d | 2010-03-05 21:31:11 +1100 | [diff] [blame] | 562 | .Xr ssh 1 |
| 563 | will try to load certificate information from the filename obtained by |
| 564 | appending |
| 565 | .Pa -cert.pub |
| 566 | to the path of a specified |
| 567 | .Cm IdentityFile . |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 568 | .Pp |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 569 | The file name may use the tilde |
Damien Miller | c6437cf | 2006-03-31 23:14:41 +1100 | [diff] [blame] | 570 | syntax to refer to a user's home directory or one of the following |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 571 | escape characters: |
| 572 | .Ql %d |
| 573 | (local user's home directory), |
| 574 | .Ql %u |
| 575 | (local user name), |
| 576 | .Ql %l |
| 577 | (local host name), |
| 578 | .Ql %h |
| 579 | (remote host name) or |
Damien Miller | dfc6183 | 2006-03-31 23:14:57 +1100 | [diff] [blame] | 580 | .Ql %r |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 581 | (remote user name). |
| 582 | .Pp |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 583 | It is possible to have |
| 584 | multiple identity files specified in configuration files; all these |
| 585 | identities will be tried in sequence. |
Damien Miller | cfb606c | 2007-10-26 14:24:48 +1000 | [diff] [blame] | 586 | .It Cm KbdInteractiveAuthentication |
| 587 | Specifies whether to use keyboard-interactive authentication. |
| 588 | The argument to this keyword must be |
| 589 | .Dq yes |
| 590 | or |
| 591 | .Dq no . |
| 592 | The default is |
| 593 | .Dq yes . |
Darren Tucker | 636ca90 | 2004-11-05 20:22:00 +1100 | [diff] [blame] | 594 | .It Cm KbdInteractiveDevices |
| 595 | Specifies the list of methods to use in keyboard-interactive authentication. |
| 596 | Multiple method names must be comma-separated. |
| 597 | The default is to use the server specified list. |
Damien Miller | 9cfbaec | 2006-03-15 11:57:55 +1100 | [diff] [blame] | 598 | The methods available vary depending on what the server supports. |
| 599 | For an OpenSSH server, |
| 600 | it may be zero or more of: |
| 601 | .Dq bsdauth , |
| 602 | .Dq pam , |
| 603 | and |
| 604 | .Dq skey . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 605 | .It Cm LocalCommand |
| 606 | Specifies a command to execute on the local machine after successfully |
| 607 | connecting to the server. |
| 608 | The command string extends to the end of the line, and is executed with |
Darren Tucker | 63b31cb | 2007-12-02 23:09:30 +1100 | [diff] [blame] | 609 | the user's shell. |
Darren Tucker | f6b01b7 | 2008-06-13 04:56:37 +1000 | [diff] [blame] | 610 | The following escape character substitutions will be performed: |
| 611 | .Ql %d |
| 612 | (local user's home directory), |
| 613 | .Ql %h |
| 614 | (remote host name), |
| 615 | .Ql %l |
| 616 | (local host name), |
| 617 | .Ql %n |
| 618 | (host name as provided on the command line), |
| 619 | .Ql %p |
| 620 | (remote port), |
| 621 | .Ql %r |
| 622 | (remote user name) or |
| 623 | .Ql %u |
| 624 | (local user name). |
Darren Tucker | 78be8c5 | 2010-01-08 17:05:59 +1100 | [diff] [blame] | 625 | .Pp |
| 626 | The command is run synchronously and does not have access to the |
| 627 | session of the |
| 628 | .Xr ssh 1 |
| 629 | that spawned it. |
| 630 | It should not be used for interactive commands. |
| 631 | .Pp |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 632 | This directive is ignored unless |
| 633 | .Cm PermitLocalCommand |
| 634 | has been enabled. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 635 | .It Cm LocalForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 636 | Specifies that a TCP port on the local machine be forwarded over |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 637 | the secure channel to the specified host and port from the remote machine. |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 638 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 639 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 640 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 641 | .Sm on |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 642 | and the second argument must be |
| 643 | .Ar host : Ns Ar hostport . |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 644 | IPv6 addresses can be specified by enclosing addresses in square brackets or |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 645 | by using an alternative syntax: |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 646 | .Oo Ar bind_address Ns / Oc Ns Ar port |
| 647 | and |
| 648 | .Ar host Ns / Ns Ar hostport . |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 649 | Multiple forwardings may be specified, and additional forwardings can be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 650 | given on the command line. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 651 | Only the superuser can forward privileged ports. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 652 | By default, the local port is bound in accordance with the |
| 653 | .Cm GatewayPorts |
| 654 | setting. |
| 655 | However, an explicit |
| 656 | .Ar bind_address |
| 657 | may be used to bind the connection to a specific address. |
| 658 | The |
| 659 | .Ar bind_address |
| 660 | of |
| 661 | .Dq localhost |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 662 | indicates that the listening port be bound for local use only, while an |
| 663 | empty address or |
| 664 | .Sq * |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 665 | indicates that the port should be available from all interfaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 666 | .It Cm LogLevel |
| 667 | Gives the verbosity level that is used when logging messages from |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 668 | .Xr ssh 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 669 | The possible values are: |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 670 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 671 | The default is INFO. |
| 672 | DEBUG and DEBUG1 are equivalent. |
| 673 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 674 | .It Cm MACs |
| 675 | Specifies the MAC (message authentication code) algorithms |
| 676 | in order of preference. |
| 677 | The MAC algorithm is used in protocol version 2 |
| 678 | for data integrity protection. |
| 679 | Multiple algorithms must be comma-separated. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 680 | The default is: |
Damien Miller | 5e7c30b | 2007-06-11 14:06:32 +1000 | [diff] [blame] | 681 | .Bd -literal -offset indent |
| 682 | hmac-md5,hmac-sha1,umac-64@openssh.com, |
| 683 | hmac-ripemd160,hmac-sha1-96,hmac-md5-96 |
| 684 | .Ed |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 685 | .It Cm NoHostAuthenticationForLocalhost |
| 686 | This option can be used if the home directory is shared across machines. |
| 687 | In this case localhost will refer to a different machine on each of |
| 688 | the machines and the user will get many warnings about changed host keys. |
| 689 | However, this option disables host authentication for localhost. |
| 690 | The argument to this keyword must be |
| 691 | .Dq yes |
| 692 | or |
| 693 | .Dq no . |
| 694 | The default is to check the host key for localhost. |
| 695 | .It Cm NumberOfPasswordPrompts |
| 696 | Specifies the number of password prompts before giving up. |
| 697 | The argument to this keyword must be an integer. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 698 | The default is 3. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 699 | .It Cm PasswordAuthentication |
| 700 | Specifies whether to use password authentication. |
| 701 | The argument to this keyword must be |
| 702 | .Dq yes |
| 703 | or |
| 704 | .Dq no . |
| 705 | The default is |
| 706 | .Dq yes . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 707 | .It Cm PermitLocalCommand |
| 708 | Allow local command execution via the |
| 709 | .Ic LocalCommand |
| 710 | option or using the |
Damien Miller | 4b2319f | 2005-12-13 19:30:27 +1100 | [diff] [blame] | 711 | .Ic !\& Ns Ar command |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 712 | escape sequence in |
| 713 | .Xr ssh 1 . |
| 714 | The argument must be |
| 715 | .Dq yes |
| 716 | or |
| 717 | .Dq no . |
| 718 | The default is |
| 719 | .Dq no . |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 720 | .It Cm PKCS11Provider |
| 721 | Specifies which PKCS#11 provider to use. |
| 722 | The argument to this keyword is the PKCS#11 shared libary |
| 723 | .Xr ssh 1 |
Damien Miller | a761844 | 2010-02-12 09:26:02 +1100 | [diff] [blame] | 724 | should use to communicate with a PKCS#11 token providing the user's |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 725 | private RSA key. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 726 | .It Cm Port |
| 727 | Specifies the port number to connect on the remote host. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 728 | The default is 22. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 729 | .It Cm PreferredAuthentications |
| 730 | Specifies the order in which the client should try protocol 2 |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 731 | authentication methods. |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 732 | This allows a client to prefer one method (e.g.\& |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 733 | .Cm keyboard-interactive ) |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 734 | over another method (e.g.\& |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 735 | .Cm password ) |
| 736 | The default for this option is: |
Damien Miller | 3c6ed7b | 2006-06-13 13:01:41 +1000 | [diff] [blame] | 737 | .Do gssapi-with-mic , |
| 738 | hostbased, |
| 739 | publickey, |
| 740 | keyboard-interactive, |
| 741 | password |
| 742 | .Dc . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 743 | .It Cm Protocol |
| 744 | Specifies the protocol versions |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 745 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 746 | should support in order of preference. |
| 747 | The possible values are |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 748 | .Sq 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 749 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 750 | .Sq 2 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 751 | Multiple versions must be comma-separated. |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 752 | When this option is set to |
Darren Tucker | 7a4a765 | 2009-10-11 21:51:40 +1100 | [diff] [blame] | 753 | .Dq 2,1 |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 754 | .Nm ssh |
| 755 | will try version 2 and fall back to version 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 756 | if version 2 is not available. |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 757 | The default is |
Darren Tucker | 7a4a765 | 2009-10-11 21:51:40 +1100 | [diff] [blame] | 758 | .Sq 2 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 759 | .It Cm ProxyCommand |
| 760 | Specifies the command to use to connect to the server. |
| 761 | The command |
| 762 | string extends to the end of the line, and is executed with |
Darren Tucker | 63b31cb | 2007-12-02 23:09:30 +1100 | [diff] [blame] | 763 | the user's shell. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 764 | In the command string, |
| 765 | .Ql %h |
| 766 | will be substituted by the host name to |
| 767 | connect and |
| 768 | .Ql %p |
| 769 | by the port. |
| 770 | The command can be basically anything, |
| 771 | and should read from its standard input and write to its standard output. |
| 772 | It should eventually connect an |
| 773 | .Xr sshd 8 |
| 774 | server running on some machine, or execute |
| 775 | .Ic sshd -i |
| 776 | somewhere. |
| 777 | Host key management will be done using the |
| 778 | HostName of the host being connected (defaulting to the name typed by |
| 779 | the user). |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 780 | Setting the command to |
| 781 | .Dq none |
Damien Miller | 9f1e33a | 2003-02-24 11:57:32 +1100 | [diff] [blame] | 782 | disables this option entirely. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 783 | Note that |
| 784 | .Cm CheckHostIP |
| 785 | is not available for connects with a proxy command. |
| 786 | .Pp |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 787 | This directive is useful in conjunction with |
| 788 | .Xr nc 1 |
| 789 | and its proxy support. |
Damien Miller | dfec294 | 2005-05-26 12:14:32 +1000 | [diff] [blame] | 790 | For example, the following directive would connect via an HTTP proxy at |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 791 | 192.0.2.0: |
| 792 | .Bd -literal -offset 3n |
| 793 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p |
| 794 | .Ed |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 795 | .It Cm PubkeyAuthentication |
| 796 | Specifies whether to try public key authentication. |
| 797 | The argument to this keyword must be |
| 798 | .Dq yes |
| 799 | or |
| 800 | .Dq no . |
| 801 | The default is |
| 802 | .Dq yes . |
| 803 | This option applies to protocol version 2 only. |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 804 | .It Cm RekeyLimit |
| 805 | Specifies the maximum amount of data that may be transmitted before the |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 806 | session key is renegotiated. |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 807 | The argument is the number of bytes, with an optional suffix of |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 808 | .Sq K , |
| 809 | .Sq M , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 810 | or |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 811 | .Sq G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 812 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. |
| 813 | The default is between |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 814 | .Sq 1G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 815 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 816 | .Sq 4G , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 817 | depending on the cipher. |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 818 | This option applies to protocol version 2 only. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 819 | .It Cm RemoteForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 820 | Specifies that a TCP port on the remote machine be forwarded over |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 821 | the secure channel to the specified host and port from the local machine. |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 822 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 823 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 824 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 825 | .Sm on |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 826 | and the second argument must be |
| 827 | .Ar host : Ns Ar hostport . |
| 828 | IPv6 addresses can be specified by enclosing addresses in square brackets |
| 829 | or by using an alternative syntax: |
| 830 | .Oo Ar bind_address Ns / Oc Ns Ar port |
| 831 | and |
| 832 | .Ar host Ns / Ns Ar hostport . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 833 | Multiple forwardings may be specified, and additional |
| 834 | forwardings can be given on the command line. |
Damien Miller | de7532e | 2008-11-03 19:24:45 +1100 | [diff] [blame] | 835 | Privileged ports can be forwarded only when |
| 836 | logging in as root on the remote machine. |
Damien Miller | e379e10 | 2009-02-14 16:34:39 +1100 | [diff] [blame] | 837 | .Pp |
Damien Miller | 85c6d8a | 2009-02-14 16:34:21 +1100 | [diff] [blame] | 838 | If the |
| 839 | .Ar port |
| 840 | argument is |
| 841 | .Ql 0 , |
| 842 | the listen port will be dynamically allocated on the server and reported |
| 843 | to the client at run time. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 844 | .Pp |
| 845 | If the |
| 846 | .Ar bind_address |
| 847 | is not specified, the default is to only bind to loopback addresses. |
| 848 | If the |
| 849 | .Ar bind_address |
| 850 | is |
| 851 | .Ql * |
| 852 | or an empty string, then the forwarding is requested to listen on all |
| 853 | interfaces. |
| 854 | Specifying a remote |
| 855 | .Ar bind_address |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 856 | will only succeed if the server's |
| 857 | .Cm GatewayPorts |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 858 | option is enabled (see |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 859 | .Xr sshd_config 5 ) . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 860 | .It Cm RhostsRSAAuthentication |
| 861 | Specifies whether to try rhosts based authentication with RSA host |
| 862 | authentication. |
| 863 | The argument must be |
| 864 | .Dq yes |
| 865 | or |
| 866 | .Dq no . |
| 867 | The default is |
| 868 | .Dq no . |
| 869 | This option applies to protocol version 1 only and requires |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 870 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 871 | to be setuid root. |
| 872 | .It Cm RSAAuthentication |
| 873 | Specifies whether to try RSA authentication. |
| 874 | The argument to this keyword must be |
| 875 | .Dq yes |
| 876 | or |
| 877 | .Dq no . |
| 878 | RSA authentication will only be |
| 879 | attempted if the identity file exists, or an authentication agent is |
| 880 | running. |
| 881 | The default is |
| 882 | .Dq yes . |
| 883 | Note that this option applies to protocol version 1 only. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 884 | .It Cm SendEnv |
| 885 | Specifies what variables from the local |
| 886 | .Xr environ 7 |
| 887 | should be sent to the server. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 888 | Note that environment passing is only supported for protocol 2. |
| 889 | The server must also support it, and the server must be configured to |
Darren Tucker | 1e0c9bf | 2004-05-02 22:12:48 +1000 | [diff] [blame] | 890 | accept these environment variables. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 891 | Refer to |
| 892 | .Cm AcceptEnv |
| 893 | in |
| 894 | .Xr sshd_config 5 |
| 895 | for how to configure the server. |
Damien Miller | 6def551 | 2006-03-15 11:54:05 +1100 | [diff] [blame] | 896 | Variables are specified by name, which may contain wildcard characters. |
Darren Tucker | 1e0c9bf | 2004-05-02 22:12:48 +1000 | [diff] [blame] | 897 | Multiple environment variables may be separated by whitespace or spread |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 898 | across multiple |
| 899 | .Cm SendEnv |
| 900 | directives. |
| 901 | The default is not to send any environment variables. |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 902 | .Pp |
| 903 | See |
| 904 | .Sx PATTERNS |
| 905 | for more information on patterns. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 906 | .It Cm ServerAliveCountMax |
Damien Miller | b797770 | 2006-01-03 18:47:31 +1100 | [diff] [blame] | 907 | Sets the number of server alive messages (see below) which may be |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 908 | sent without |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 909 | .Xr ssh 1 |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 910 | receiving any messages back from the server. |
| 911 | If this threshold is reached while server alive messages are being sent, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 912 | ssh will disconnect from the server, terminating the session. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 913 | It is important to note that the use of server alive messages is very |
| 914 | different from |
| 915 | .Cm TCPKeepAlive |
| 916 | (below). |
| 917 | The server alive messages are sent through the encrypted channel |
| 918 | and therefore will not be spoofable. |
| 919 | The TCP keepalive option enabled by |
| 920 | .Cm TCPKeepAlive |
| 921 | is spoofable. |
| 922 | The server alive mechanism is valuable when the client or |
| 923 | server depend on knowing when a connection has become inactive. |
| 924 | .Pp |
| 925 | The default value is 3. |
| 926 | If, for example, |
| 927 | .Cm ServerAliveInterval |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 928 | (see below) is set to 15 and |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 929 | .Cm ServerAliveCountMax |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 930 | is left at the default, if the server becomes unresponsive, |
| 931 | ssh will disconnect after approximately 45 seconds. |
Damien Miller | cc3e8ba | 2006-03-15 12:06:55 +1100 | [diff] [blame] | 932 | This option applies to protocol version 2 only. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 933 | .It Cm ServerAliveInterval |
| 934 | Sets a timeout interval in seconds after which if no data has been received |
| 935 | from the server, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 936 | .Xr ssh 1 |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 937 | will send a message through the encrypted |
| 938 | channel to request a response from the server. |
| 939 | The default |
| 940 | is 0, indicating that these messages will not be sent to the server. |
| 941 | This option applies to protocol version 2 only. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 942 | .It Cm StrictHostKeyChecking |
| 943 | If this flag is set to |
| 944 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 945 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 946 | will never automatically add host keys to the |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 947 | .Pa ~/.ssh/known_hosts |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 948 | file, and refuses to connect to hosts whose host key has changed. |
| 949 | This provides maximum protection against trojan horse attacks, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 950 | though it can be annoying when the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 951 | .Pa /etc/ssh/ssh_known_hosts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 952 | file is poorly maintained or when connections to new hosts are |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 953 | frequently made. |
| 954 | This option forces the user to manually |
| 955 | add all new hosts. |
| 956 | If this flag is set to |
| 957 | .Dq no , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 958 | ssh will automatically add new host keys to the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 959 | user known hosts files. |
| 960 | If this flag is set to |
| 961 | .Dq ask , |
| 962 | new host keys |
| 963 | will be added to the user known host files only after the user |
| 964 | has confirmed that is what they really want to do, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 965 | ssh will refuse to connect to hosts whose host key has changed. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 966 | The host keys of |
| 967 | known hosts will be verified automatically in all cases. |
| 968 | The argument must be |
| 969 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 970 | .Dq no , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 971 | or |
| 972 | .Dq ask . |
| 973 | The default is |
| 974 | .Dq ask . |
Damien Miller | 12c150e | 2003-12-17 16:31:10 +1100 | [diff] [blame] | 975 | .It Cm TCPKeepAlive |
| 976 | Specifies whether the system should send TCP keepalive messages to the |
| 977 | other side. |
| 978 | If they are sent, death of the connection or crash of one |
| 979 | of the machines will be properly noticed. |
| 980 | However, this means that |
| 981 | connections will die if the route is down temporarily, and some people |
| 982 | find it annoying. |
| 983 | .Pp |
| 984 | The default is |
| 985 | .Dq yes |
| 986 | (to send TCP keepalive messages), and the client will notice |
| 987 | if the network goes down or the remote host dies. |
| 988 | This is important in scripts, and many users want it too. |
| 989 | .Pp |
| 990 | To disable TCP keepalive messages, the value should be set to |
| 991 | .Dq no . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 992 | .It Cm Tunnel |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 993 | Request |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 994 | .Xr tun 4 |
Damien Miller | 7746c39 | 2005-12-13 19:33:37 +1100 | [diff] [blame] | 995 | device forwarding between the client and the server. |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 996 | The argument must be |
Damien Miller | 7b58e80 | 2005-12-13 19:33:19 +1100 | [diff] [blame] | 997 | .Dq yes , |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 998 | .Dq point-to-point |
| 999 | (layer 3), |
| 1000 | .Dq ethernet |
| 1001 | (layer 2), |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1002 | or |
| 1003 | .Dq no . |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1004 | Specifying |
| 1005 | .Dq yes |
| 1006 | requests the default tunnel mode, which is |
| 1007 | .Dq point-to-point . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1008 | The default is |
| 1009 | .Dq no . |
| 1010 | .It Cm TunnelDevice |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1011 | Specifies the |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1012 | .Xr tun 4 |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1013 | devices to open on the client |
| 1014 | .Pq Ar local_tun |
| 1015 | and the server |
| 1016 | .Pq Ar remote_tun . |
| 1017 | .Pp |
| 1018 | The argument must be |
| 1019 | .Sm off |
| 1020 | .Ar local_tun Op : Ar remote_tun . |
| 1021 | .Sm on |
| 1022 | The devices may be specified by numerical ID or the keyword |
| 1023 | .Dq any , |
| 1024 | which uses the next available tunnel device. |
| 1025 | If |
| 1026 | .Ar remote_tun |
| 1027 | is not specified, it defaults to |
| 1028 | .Dq any . |
| 1029 | The default is |
| 1030 | .Dq any:any . |
Damien Miller | e8cd741 | 2005-12-24 14:55:47 +1100 | [diff] [blame] | 1031 | .It Cm UsePrivilegedPort |
| 1032 | Specifies whether to use a privileged port for outgoing connections. |
| 1033 | The argument must be |
| 1034 | .Dq yes |
| 1035 | or |
| 1036 | .Dq no . |
| 1037 | The default is |
| 1038 | .Dq no . |
| 1039 | If set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1040 | .Dq yes , |
| 1041 | .Xr ssh 1 |
Damien Miller | e8cd741 | 2005-12-24 14:55:47 +1100 | [diff] [blame] | 1042 | must be setuid root. |
| 1043 | Note that this option must be set to |
| 1044 | .Dq yes |
| 1045 | for |
| 1046 | .Cm RhostsRSAAuthentication |
| 1047 | with older servers. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1048 | .It Cm User |
| 1049 | Specifies the user to log in as. |
| 1050 | This can be useful when a different user name is used on different machines. |
| 1051 | This saves the trouble of |
| 1052 | having to remember to give the user name on the command line. |
| 1053 | .It Cm UserKnownHostsFile |
| 1054 | Specifies a file to use for the user |
| 1055 | host key database instead of |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1056 | .Pa ~/.ssh/known_hosts . |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1057 | .It Cm VerifyHostKeyDNS |
| 1058 | Specifies whether to verify the remote key using DNS and SSHFP resource |
| 1059 | records. |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1060 | If this option is set to |
| 1061 | .Dq yes , |
Damien Miller | fe44847 | 2003-11-17 21:19:49 +1100 | [diff] [blame] | 1062 | the client will implicitly trust keys that match a secure fingerprint |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1063 | from DNS. |
| 1064 | Insecure fingerprints will be handled as if this option was set to |
| 1065 | .Dq ask . |
| 1066 | If this option is set to |
| 1067 | .Dq ask , |
| 1068 | information on fingerprint match will be displayed, but the user will still |
| 1069 | need to confirm new host keys according to the |
| 1070 | .Cm StrictHostKeyChecking |
| 1071 | option. |
| 1072 | The argument must be |
| 1073 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1074 | .Dq no , |
Damien Miller | fe44847 | 2003-11-17 21:19:49 +1100 | [diff] [blame] | 1075 | or |
| 1076 | .Dq ask . |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1077 | The default is |
| 1078 | .Dq no . |
Damien Miller | eacbb4f | 2003-06-02 19:10:41 +1000 | [diff] [blame] | 1079 | Note that this option applies to protocol version 2 only. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1080 | .Pp |
| 1081 | See also |
| 1082 | .Sx VERIFYING HOST KEYS |
| 1083 | in |
| 1084 | .Xr ssh 1 . |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1085 | .It Cm VisualHostKey |
| 1086 | If this flag is set to |
| 1087 | .Dq yes , |
| 1088 | an ASCII art representation of the remote host key fingerprint is |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1089 | printed in addition to the hex fingerprint string at login and |
| 1090 | for unknown host keys. |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1091 | If this flag is set to |
| 1092 | .Dq no , |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1093 | no fingerprint strings are printed at login and |
| 1094 | only the hex fingerprint string will be printed for unknown host keys. |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1095 | The default is |
| 1096 | .Dq no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1097 | .It Cm XAuthLocation |
Damien Miller | 05913ba | 2002-09-04 16:51:03 +1000 | [diff] [blame] | 1098 | Specifies the full pathname of the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1099 | .Xr xauth 1 |
| 1100 | program. |
| 1101 | The default is |
| 1102 | .Pa /usr/X11R6/bin/xauth . |
| 1103 | .El |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1104 | .Sh PATTERNS |
| 1105 | A |
| 1106 | .Em pattern |
| 1107 | consists of zero or more non-whitespace characters, |
| 1108 | .Sq * |
| 1109 | (a wildcard that matches zero or more characters), |
| 1110 | or |
| 1111 | .Sq ?\& |
| 1112 | (a wildcard that matches exactly one character). |
| 1113 | For example, to specify a set of declarations for any host in the |
| 1114 | .Dq .co.uk |
| 1115 | set of domains, |
| 1116 | the following pattern could be used: |
| 1117 | .Pp |
| 1118 | .Dl Host *.co.uk |
| 1119 | .Pp |
| 1120 | The following pattern |
| 1121 | would match any host in the 192.168.0.[0-9] network range: |
| 1122 | .Pp |
| 1123 | .Dl Host 192.168.0.? |
| 1124 | .Pp |
| 1125 | A |
| 1126 | .Em pattern-list |
| 1127 | is a comma-separated list of patterns. |
| 1128 | Patterns within pattern-lists may be negated |
| 1129 | by preceding them with an exclamation mark |
| 1130 | .Pq Sq !\& . |
| 1131 | For example, |
| 1132 | to allow a key to be used from anywhere within an organisation |
| 1133 | except from the |
| 1134 | .Dq dialup |
| 1135 | pool, |
| 1136 | the following entry (in authorized_keys) could be used: |
| 1137 | .Pp |
| 1138 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1139 | .Sh FILES |
| 1140 | .Bl -tag -width Ds |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1141 | .It Pa ~/.ssh/config |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1142 | This is the per-user configuration file. |
| 1143 | The format of this file is described above. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1144 | This file is used by the SSH client. |
Damien Miller | c970cb9 | 2004-04-20 20:12:53 +1000 | [diff] [blame] | 1145 | Because of the potential for abuse, this file must have strict permissions: |
| 1146 | read/write for the user, and not accessible by others. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1147 | .It Pa /etc/ssh/ssh_config |
| 1148 | Systemwide configuration file. |
| 1149 | This file provides defaults for those |
| 1150 | values that are not specified in the user's configuration file, and |
| 1151 | for those users who do not have a configuration file. |
| 1152 | This file must be world-readable. |
| 1153 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 1154 | .Sh SEE ALSO |
| 1155 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1156 | .Sh AUTHORS |
| 1157 | OpenSSH is a derivative of the original and free |
| 1158 | ssh 1.2.12 release by Tatu Ylonen. |
| 1159 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, |
| 1160 | Theo de Raadt and Dug Song |
| 1161 | removed many bugs, re-added newer features and |
| 1162 | created OpenSSH. |
| 1163 | Markus Friedl contributed the support for SSH |
| 1164 | protocol versions 1.5 and 2.0. |