Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1 | .\" |
| 2 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 3 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 4 | .\" All rights reserved |
| 5 | .\" |
| 6 | .\" As far as I am concerned, the code I have written for this software |
| 7 | .\" can be used freely for any purpose. Any derived versions of this |
| 8 | .\" software must be clearly marked as such, and if the derived work is |
| 9 | .\" incompatible with the protocol description in the RFC file, it must be |
| 10 | .\" called by a name other than "ssh" or "Secure Shell". |
| 11 | .\" |
| 12 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. |
| 13 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. |
| 14 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. |
| 15 | .\" |
| 16 | .\" Redistribution and use in source and binary forms, with or without |
| 17 | .\" modification, are permitted provided that the following conditions |
| 18 | .\" are met: |
| 19 | .\" 1. Redistributions of source code must retain the above copyright |
| 20 | .\" notice, this list of conditions and the following disclaimer. |
| 21 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| 22 | .\" notice, this list of conditions and the following disclaimer in the |
| 23 | .\" documentation and/or other materials provided with the distribution. |
| 24 | .\" |
| 25 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 26 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 27 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 28 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 29 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 30 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 31 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 32 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 33 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 34 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 35 | .\" |
dtucker@openbsd.org | ed833da | 2020-04-03 02:27:12 +0000 | [diff] [blame^] | 36 | .\" $OpenBSD: ssh_config.5,v 1.323 2020/04/03 02:27:12 dtucker Exp $ |
| 37 | .Dd $Mdocdate: April 3 2020 $ |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 38 | .Dt SSH_CONFIG 5 |
| 39 | .Os |
| 40 | .Sh NAME |
| 41 | .Nm ssh_config |
jmc@openbsd.org | 483cc72 | 2019-11-30 07:07:59 +0000 | [diff] [blame] | 42 | .Nd OpenSSH client configuration file |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 43 | .Sh DESCRIPTION |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 44 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 45 | obtains configuration data from the following sources in |
| 46 | the following order: |
Damien Miller | 5c853b5 | 2006-03-15 11:37:02 +1100 | [diff] [blame] | 47 | .Pp |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 48 | .Bl -enum -offset indent -compact |
| 49 | .It |
| 50 | command-line options |
| 51 | .It |
| 52 | user's configuration file |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 53 | .Pq Pa ~/.ssh/config |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 54 | .It |
| 55 | system-wide configuration file |
| 56 | .Pq Pa /etc/ssh/ssh_config |
| 57 | .El |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 58 | .Pp |
| 59 | For each parameter, the first obtained value |
| 60 | will be used. |
Darren Tucker | 43d8e28 | 2005-02-09 09:51:08 +1100 | [diff] [blame] | 61 | The configuration files contain sections separated by |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 62 | .Cm Host |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 63 | specifications, and that section is only applied for hosts that |
| 64 | match one of the patterns given in the specification. |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 65 | The matched host name is usually the one given on the command line |
| 66 | (see the |
| 67 | .Cm CanonicalizeHostname |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 68 | option for exceptions). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 69 | .Pp |
| 70 | Since the first obtained value for each parameter is used, more |
| 71 | host-specific declarations should be given near the beginning of the |
| 72 | file, and general defaults at the end. |
| 73 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 74 | The file contains keyword-argument pairs, one per line. |
| 75 | Lines starting with |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 76 | .Ql # |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 77 | and empty lines are interpreted as comments. |
| 78 | Arguments may optionally be enclosed in double quotes |
| 79 | .Pq \&" |
| 80 | in order to represent arguments containing spaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 81 | Configuration options may be separated by whitespace or |
| 82 | optional whitespace and exactly one |
| 83 | .Ql = ; |
| 84 | the latter format is useful to avoid the need to quote whitespace |
| 85 | when specifying configuration options using the |
| 86 | .Nm ssh , |
Damien Miller | 4aea974 | 2006-03-15 11:59:39 +1100 | [diff] [blame] | 87 | .Nm scp , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 88 | and |
| 89 | .Nm sftp |
| 90 | .Fl o |
| 91 | option. |
| 92 | .Pp |
| 93 | The possible |
| 94 | keywords and their meanings are as follows (note that |
| 95 | keywords are case-insensitive and arguments are case-sensitive): |
| 96 | .Bl -tag -width Ds |
| 97 | .It Cm Host |
| 98 | Restricts the following declarations (up to the next |
| 99 | .Cm Host |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 100 | or |
| 101 | .Cm Match |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 102 | keyword) to be only for those hosts that match one of the patterns |
| 103 | given after the keyword. |
Damien Miller | fa51b16 | 2008-11-03 19:17:33 +1100 | [diff] [blame] | 104 | 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] | 105 | A single |
Damien Miller | 208f1ed | 2006-03-15 11:56:03 +1100 | [diff] [blame] | 106 | .Ql * |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 107 | as a pattern can be used to provide global |
| 108 | defaults for all hosts. |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 109 | The host is usually the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 110 | .Ar hostname |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 111 | argument given on the command line |
| 112 | (see the |
| 113 | .Cm CanonicalizeHostname |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 114 | keyword for exceptions). |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 115 | .Pp |
Damien Miller | fe92421 | 2011-05-15 08:44:45 +1000 | [diff] [blame] | 116 | A pattern entry may be negated by prefixing it with an exclamation mark |
| 117 | .Pq Sq !\& . |
| 118 | If a negated entry is matched, then the |
| 119 | .Cm Host |
| 120 | entry is ignored, regardless of whether any other patterns on the line |
| 121 | match. |
| 122 | Negated matches are therefore useful to provide exceptions for wildcard |
| 123 | matches. |
| 124 | .Pp |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 125 | See |
| 126 | .Sx PATTERNS |
| 127 | for more information on patterns. |
Damien Miller | d77b81f | 2013-10-17 11:39:00 +1100 | [diff] [blame] | 128 | .It Cm Match |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 129 | Restricts the following declarations (up to the next |
| 130 | .Cm Host |
| 131 | or |
| 132 | .Cm Match |
| 133 | keyword) to be used only when the conditions following the |
| 134 | .Cm Match |
| 135 | keyword are satisfied. |
sobrado@openbsd.org | e3cbb06 | 2015-09-22 08:33:23 +0000 | [diff] [blame] | 136 | Match conditions are specified using one or more criteria |
Damien Miller | cf31f38 | 2013-10-24 21:02:56 +1100 | [diff] [blame] | 137 | or the single token |
| 138 | .Cm all |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 139 | which always matches. |
| 140 | The available criteria keywords are: |
| 141 | .Cm canonical , |
djm@openbsd.org | 9e34e0c | 2018-11-23 05:08:07 +0000 | [diff] [blame] | 142 | .Cm final , |
Damien Miller | 8a04be7 | 2013-10-23 16:29:40 +1100 | [diff] [blame] | 143 | .Cm exec , |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 144 | .Cm host , |
| 145 | .Cm originalhost , |
| 146 | .Cm user , |
| 147 | and |
| 148 | .Cm localuser . |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 149 | The |
| 150 | .Cm all |
| 151 | criteria must appear alone or immediately after |
djm@openbsd.org | 9e34e0c | 2018-11-23 05:08:07 +0000 | [diff] [blame] | 152 | .Cm canonical |
| 153 | or |
| 154 | .Cm final . |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 155 | Other criteria may be combined arbitrarily. |
| 156 | All criteria but |
jmc@openbsd.org | dd0cf63 | 2018-11-23 06:58:28 +0000 | [diff] [blame] | 157 | .Cm all , |
| 158 | .Cm canonical , |
djm@openbsd.org | 9e34e0c | 2018-11-23 05:08:07 +0000 | [diff] [blame] | 159 | and |
| 160 | .Cm final |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 161 | require an argument. |
| 162 | Criteria may be negated by prepending an exclamation mark |
| 163 | .Pq Sq !\& . |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 164 | .Pp |
Damien Miller | 8e5a67f | 2013-10-23 16:30:25 +1100 | [diff] [blame] | 165 | The |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 166 | .Cm canonical |
dtucker@openbsd.org | dd2cfeb | 2015-05-28 05:09:45 +0000 | [diff] [blame] | 167 | keyword matches only when the configuration file is being re-parsed |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 168 | after hostname canonicalization (see the |
| 169 | .Cm CanonicalizeHostname |
jmc@openbsd.org | dd0cf63 | 2018-11-23 06:58:28 +0000 | [diff] [blame] | 170 | option). |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 171 | This may be useful to specify conditions that work with canonical host |
| 172 | names only. |
djm@openbsd.org | 9e34e0c | 2018-11-23 05:08:07 +0000 | [diff] [blame] | 173 | .Pp |
| 174 | The |
| 175 | .Cm final |
| 176 | keyword requests that the configuration be re-parsed (regardless of whether |
| 177 | .Cm CanonicalizeHostname |
| 178 | is enabled), and matches only during this final pass. |
| 179 | If |
| 180 | .Cm CanonicalizeHostname |
| 181 | is enabled, then |
| 182 | .Cm canonical |
| 183 | and |
| 184 | .Cm final |
| 185 | match during the same pass. |
| 186 | .Pp |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 187 | The |
Damien Miller | 8a04be7 | 2013-10-23 16:29:40 +1100 | [diff] [blame] | 188 | .Cm exec |
Damien Miller | 8e5a67f | 2013-10-23 16:30:25 +1100 | [diff] [blame] | 189 | keyword executes the specified command under the user's shell. |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 190 | If the command returns a zero exit status then the condition is considered true. |
| 191 | Commands containing whitespace characters must be quoted. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 192 | Arguments to |
| 193 | .Cm exec |
| 194 | accept the tokens described in the |
| 195 | .Sx TOKENS |
| 196 | section. |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 197 | .Pp |
| 198 | The other keywords' criteria must be single entries or comma-separated |
| 199 | lists and may use the wildcard and negation operators described in the |
| 200 | .Sx PATTERNS |
| 201 | section. |
| 202 | The criteria for the |
| 203 | .Cm host |
| 204 | keyword are matched against the target hostname, after any substitution |
| 205 | by the |
jmc@openbsd.org | 76af9c5 | 2019-06-12 05:53:21 +0000 | [diff] [blame] | 206 | .Cm Hostname |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 207 | or |
| 208 | .Cm CanonicalizeHostname |
| 209 | options. |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 210 | The |
| 211 | .Cm originalhost |
| 212 | keyword matches against the hostname as it was specified on the command-line. |
| 213 | The |
| 214 | .Cm user |
| 215 | keyword matches against the target username on the remote host. |
| 216 | The |
| 217 | .Cm localuser |
| 218 | keyword matches against the name of the local user running |
| 219 | .Xr ssh 1 |
| 220 | (this keyword may be useful in system-wide |
| 221 | .Nm |
| 222 | files). |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 223 | .It Cm AddKeysToAgent |
| 224 | Specifies whether keys should be automatically added to a running |
jmc@openbsd.org | e41a071 | 2015-11-15 23:58:04 +0000 | [diff] [blame] | 225 | .Xr ssh-agent 1 . |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 226 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 227 | .Cm yes |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 228 | and a key is loaded from a file, the key and its passphrase are added to |
| 229 | the agent with the default lifetime, as if by |
| 230 | .Xr ssh-add 1 . |
| 231 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 232 | .Cm ask , |
| 233 | .Xr ssh 1 |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 234 | will require confirmation using the |
| 235 | .Ev SSH_ASKPASS |
| 236 | program before adding a key (see |
| 237 | .Xr ssh-add 1 |
| 238 | for details). |
| 239 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 240 | .Cm confirm , |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 241 | each use of the key must be confirmed, as if the |
| 242 | .Fl c |
| 243 | option was specified to |
| 244 | .Xr ssh-add 1 . |
| 245 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 246 | .Cm no , |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 247 | no keys are added to the agent. |
| 248 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 249 | .Cm yes , |
| 250 | .Cm confirm , |
| 251 | .Cm ask , |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 252 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 253 | .Cm no |
| 254 | (the default). |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 255 | .It Cm AddressFamily |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 256 | Specifies which address family to use when connecting. |
| 257 | Valid arguments are |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 258 | .Cm any |
| 259 | (the default), |
| 260 | .Cm inet |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 261 | (use IPv4 only), or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 262 | .Cm inet6 |
Darren Tucker | 79a7acf | 2005-02-09 09:48:57 +1100 | [diff] [blame] | 263 | (use IPv6 only). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 264 | .It Cm BatchMode |
| 265 | If set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 266 | .Cm yes , |
djm@openbsd.org | 469df61 | 2020-01-25 23:33:27 +0000 | [diff] [blame] | 267 | user interaction such as password prompts and host key confirmation requests |
| 268 | will be disabled. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 269 | This option is useful in scripts and other batch jobs where no user |
djm@openbsd.org | 469df61 | 2020-01-25 23:33:27 +0000 | [diff] [blame] | 270 | is present to interact with |
| 271 | .Xr ssh 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 272 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 273 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 274 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 275 | .Cm no |
| 276 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 277 | .It Cm BindAddress |
Darren Tucker | 89f4d47 | 2005-07-14 17:06:21 +1000 | [diff] [blame] | 278 | 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] | 279 | the connection. |
| 280 | Only useful on systems with more than one address. |
jmc@openbsd.org | 7d330a1 | 2018-02-23 07:38:09 +0000 | [diff] [blame] | 281 | .It Cm BindInterface |
| 282 | Use the address of the specified interface on the local machine as the |
| 283 | source address of the connection. |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 284 | .It Cm CanonicalDomains |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 285 | When |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 286 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 287 | is enabled, this option specifies the list of domain suffixes in which to |
| 288 | search for the specified destination host. |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 289 | .It Cm CanonicalizeFallbackLocal |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 290 | Specifies whether to fail with an error when hostname canonicalization fails. |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 291 | The default, |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 292 | .Cm yes , |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 293 | will attempt to look up the unqualified hostname using the system resolver's |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 294 | search rules. |
| 295 | A value of |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 296 | .Cm no |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 297 | will cause |
| 298 | .Xr ssh 1 |
| 299 | to fail instantly if |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 300 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 301 | is enabled and the target hostname cannot be found in any of the domains |
| 302 | specified by |
| 303 | .Cm CanonicalDomains . |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 304 | .It Cm CanonicalizeHostname |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 305 | Controls whether explicit hostname canonicalization is performed. |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 306 | The default, |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 307 | .Cm no , |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 308 | is not to perform any name rewriting and let the system resolver handle all |
| 309 | hostname lookups. |
| 310 | If set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 311 | .Cm yes |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 312 | then, for connections that do not use a |
djm@openbsd.org | 383a33d | 2018-09-21 03:11:36 +0000 | [diff] [blame] | 313 | .Cm ProxyCommand |
| 314 | or |
| 315 | .Cm ProxyJump , |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 316 | .Xr ssh 1 |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 317 | will attempt to canonicalize the hostname specified on the command line |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 318 | using the |
| 319 | .Cm CanonicalDomains |
| 320 | suffixes and |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 321 | .Cm CanonicalizePermittedCNAMEs |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 322 | rules. |
| 323 | If |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 324 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 325 | is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 326 | .Cm always , |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 327 | then canonicalization is applied to proxied connections too. |
Damien Miller | 13f97b2 | 2014-02-24 15:57:55 +1100 | [diff] [blame] | 328 | .Pp |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 329 | If this option is enabled, then the configuration files are processed |
| 330 | again using the new target name to pick up any new configuration in matching |
Damien Miller | 13f97b2 | 2014-02-24 15:57:55 +1100 | [diff] [blame] | 331 | .Cm Host |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 332 | and |
| 333 | .Cm Match |
Damien Miller | 13f97b2 | 2014-02-24 15:57:55 +1100 | [diff] [blame] | 334 | stanzas. |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 335 | .It Cm CanonicalizeMaxDots |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 336 | Specifies the maximum number of dot characters in a hostname before |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 337 | canonicalization is disabled. |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 338 | The default, 1, |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 339 | allows a single dot (i.e. hostname.subdomain). |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 340 | .It Cm CanonicalizePermittedCNAMEs |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 341 | Specifies rules to determine whether CNAMEs should be followed when |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 342 | canonicalizing hostnames. |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 343 | The rules consist of one or more arguments of |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 344 | .Ar source_domain_list : Ns Ar target_domain_list , |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 345 | where |
| 346 | .Ar source_domain_list |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 347 | is a pattern-list of domains that may follow CNAMEs in canonicalization, |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 348 | and |
| 349 | .Ar target_domain_list |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 350 | is a pattern-list of domains that they may resolve to. |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 351 | .Pp |
| 352 | For example, |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 353 | .Qq *.a.example.com:*.b.example.com,*.c.example.com |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 354 | will allow hostnames matching |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 355 | .Qq *.a.example.com |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 356 | to be canonicalized to names in the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 357 | .Qq *.b.example.com |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 358 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 359 | .Qq *.c.example.com |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 360 | domains. |
jmc@openbsd.org | e6933a2 | 2018-09-20 06:58:48 +0000 | [diff] [blame] | 361 | .It Cm CASignatureAlgorithms |
| 362 | Specifies which algorithms are allowed for signing of certificates |
| 363 | by certificate authorities (CAs). |
| 364 | The default is: |
| 365 | .Bd -literal -offset indent |
djm@openbsd.org | 6e76e69 | 2019-08-02 01:23:19 +0000 | [diff] [blame] | 366 | ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, |
jmc@openbsd.org | e6933a2 | 2018-09-20 06:58:48 +0000 | [diff] [blame] | 367 | ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa |
| 368 | .Ed |
| 369 | .Pp |
| 370 | .Xr ssh 1 |
| 371 | will not accept host certificates signed using algorithms other than those |
| 372 | specified. |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 373 | .It Cm CertificateFile |
| 374 | Specifies a file from which the user's certificate is read. |
| 375 | A corresponding private key must be provided separately in order |
| 376 | to use this certificate either |
| 377 | from an |
| 378 | .Cm IdentityFile |
| 379 | directive or |
| 380 | .Fl i |
| 381 | flag to |
| 382 | .Xr ssh 1 , |
| 383 | via |
| 384 | .Xr ssh-agent 1 , |
| 385 | or via a |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 386 | .Cm PKCS11Provider |
| 387 | or |
| 388 | .Cm SecurityKeyProvider . |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 389 | .Pp |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 390 | Arguments to |
| 391 | .Cm CertificateFile |
| 392 | may use the tilde syntax to refer to a user's home directory |
| 393 | or the tokens described in the |
| 394 | .Sx TOKENS |
| 395 | section. |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 396 | .Pp |
| 397 | It is possible to have multiple certificate files specified in |
| 398 | configuration files; these certificates will be tried in sequence. |
| 399 | Multiple |
| 400 | .Cm CertificateFile |
| 401 | directives will add to the list of certificates used for |
| 402 | authentication. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 403 | .It Cm ChallengeResponseAuthentication |
Damien Miller | 1faa713 | 2006-03-15 11:55:31 +1100 | [diff] [blame] | 404 | Specifies whether to use challenge-response authentication. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 405 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 406 | .Cm yes |
| 407 | (the default) |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 408 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 409 | .Cm no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 410 | .It Cm CheckHostIP |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 411 | If set to |
| 412 | .Cm yes |
| 413 | (the default), |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 414 | .Xr ssh 1 |
| 415 | will additionally check the host IP address in the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 416 | .Pa known_hosts |
| 417 | file. |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 418 | This allows it to detect if a host key changed due to DNS spoofing |
djm@openbsd.org | 5e67859 | 2015-06-02 09:10:40 +0000 | [diff] [blame] | 419 | and will add addresses of destination hosts to |
| 420 | .Pa ~/.ssh/known_hosts |
| 421 | in the process, regardless of the setting of |
| 422 | .Cm StrictHostKeyChecking . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 423 | If the option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 424 | .Cm no , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 425 | the check will not be executed. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 426 | .It Cm Ciphers |
djm@openbsd.org | 788ac79 | 2017-04-30 23:18:22 +0000 | [diff] [blame] | 427 | Specifies the ciphers allowed and their order of preference. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 428 | Multiple ciphers must be comma-separated. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 429 | If the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 430 | .Sq + |
| 431 | character, then the specified ciphers will be appended to the default set |
| 432 | instead of replacing them. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 433 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 434 | .Sq - |
| 435 | character, then the specified ciphers (including wildcards) will be removed |
| 436 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 437 | If the specified list begins with a |
| 438 | .Sq ^ |
| 439 | character, then the specified ciphers will be placed at the head of the |
| 440 | default set. |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 441 | .Pp |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 442 | The supported ciphers are: |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 443 | .Bd -literal -offset indent |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 444 | 3des-cbc |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 445 | aes128-cbc |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 446 | aes192-cbc |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 447 | aes256-cbc |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 448 | aes128-ctr |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 449 | aes192-ctr |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 450 | aes256-ctr |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 451 | aes128-gcm@openssh.com |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 452 | aes256-gcm@openssh.com |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 453 | chacha20-poly1305@openssh.com |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 454 | .Ed |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 455 | .Pp |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 456 | The default is: |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 457 | .Bd -literal -offset indent |
jmc@openbsd.org | 1f8d3d6 | 2015-08-14 15:32:41 +0000 | [diff] [blame] | 458 | chacha20-poly1305@openssh.com, |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 459 | aes128-ctr,aes192-ctr,aes256-ctr, |
djm@openbsd.org | 00c5222 | 2018-04-05 22:54:28 +0000 | [diff] [blame] | 460 | aes128-gcm@openssh.com,aes256-gcm@openssh.com |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 461 | .Ed |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 462 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 463 | The list of available ciphers may also be obtained using |
| 464 | .Qq ssh -Q cipher . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 465 | .It Cm ClearAllForwardings |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 466 | Specifies that all local, remote, and dynamic port forwardings |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 467 | specified in the configuration files or on the command line be |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 468 | cleared. |
| 469 | This option is primarily useful when used from the |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 470 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 471 | command line to clear port forwardings set in |
| 472 | configuration files, and is automatically set by |
| 473 | .Xr scp 1 |
| 474 | and |
| 475 | .Xr sftp 1 . |
| 476 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 477 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 478 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 479 | .Cm no |
| 480 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 481 | .It Cm Compression |
| 482 | Specifies whether to use compression. |
| 483 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 484 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 485 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 486 | .Cm no |
| 487 | (the default). |
naddy@openbsd.org | 9a82e24 | 2017-05-03 21:49:18 +0000 | [diff] [blame] | 488 | .It Cm ConnectionAttempts |
| 489 | Specifies the number of tries (one per second) to make before exiting. |
| 490 | The argument must be an integer. |
| 491 | This may be useful in scripts if the connection sometimes fails. |
| 492 | The default is 1. |
Damien Miller | b78d5eb | 2003-05-16 11:39:04 +1000 | [diff] [blame] | 493 | .It Cm ConnectTimeout |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 494 | Specifies the timeout (in seconds) used when connecting to the |
| 495 | SSH server, instead of using the default system TCP timeout. |
djm@openbsd.org | 2ce1d11 | 2019-09-13 04:07:42 +0000 | [diff] [blame] | 496 | This timeout is applied both to establishing the connection and to performing |
| 497 | the initial SSH protocol handshake and key exchange. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 498 | .It Cm ControlMaster |
| 499 | Enables the sharing of multiple sessions over a single network connection. |
| 500 | When set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 501 | .Cm yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 502 | .Xr ssh 1 |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 503 | will listen for connections on a control socket specified using the |
| 504 | .Cm ControlPath |
| 505 | argument. |
| 506 | Additional sessions can connect to this socket using the same |
| 507 | .Cm ControlPath |
| 508 | with |
| 509 | .Cm ControlMaster |
| 510 | set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 511 | .Cm no |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 512 | (the default). |
Damien Miller | 713de76 | 2005-11-05 15:13:49 +1100 | [diff] [blame] | 513 | These sessions will try to reuse the master instance's network connection |
Damien Miller | b3bfbb7 | 2005-11-05 15:11:48 +1100 | [diff] [blame] | 514 | rather than initiating new ones, but will fall back to connecting normally |
| 515 | if the control socket does not exist, or is not listening. |
| 516 | .Pp |
Damien Miller | 23f0770 | 2004-06-18 01:19:03 +1000 | [diff] [blame] | 517 | Setting this to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 518 | .Cm ask |
| 519 | will cause |
| 520 | .Xr ssh 1 |
jmc@openbsd.org | 78de167 | 2015-03-30 18:28:37 +0000 | [diff] [blame] | 521 | to listen for control connections, but require confirmation using |
| 522 | .Xr ssh-askpass 1 . |
Damien Miller | dadfd4d | 2005-05-26 12:07:13 +1000 | [diff] [blame] | 523 | If the |
| 524 | .Cm ControlPath |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 525 | cannot be opened, |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 526 | .Xr ssh 1 |
| 527 | will continue without connecting to a master instance. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 528 | .Pp |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 529 | X11 and |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 530 | .Xr ssh-agent 1 |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 531 | forwarding is supported over these multiplexed connections, however the |
Darren Tucker | 6355187 | 2005-12-20 16:14:15 +1100 | [diff] [blame] | 532 | display and agent forwarded will be the one belonging to the master |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 533 | 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] | 534 | .Pp |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 535 | Two additional options allow for opportunistic multiplexing: try to use a |
| 536 | master connection but fall back to creating a new one if one does not already |
| 537 | exist. |
| 538 | These options are: |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 539 | .Cm auto |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 540 | and |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 541 | .Cm autoask . |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 542 | The latter requires confirmation like the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 543 | .Cm ask |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 544 | option. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 545 | .It Cm ControlPath |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 546 | Specify the path to the control socket used for connection sharing as described |
| 547 | in the |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 548 | .Cm ControlMaster |
Damien Miller | 8f74c8f | 2005-06-26 08:56:03 +1000 | [diff] [blame] | 549 | section above or the string |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 550 | .Cm none |
Damien Miller | 8f74c8f | 2005-06-26 08:56:03 +1000 | [diff] [blame] | 551 | to disable connection sharing. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 552 | Arguments to |
| 553 | .Cm ControlPath |
| 554 | may use the tilde syntax to refer to a user's home directory |
| 555 | or the tokens described in the |
| 556 | .Sx TOKENS |
| 557 | section. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 558 | It is recommended that any |
| 559 | .Cm ControlPath |
| 560 | used for opportunistic connection sharing include |
djm@openbsd.org | fc30256 | 2014-11-10 22:25:49 +0000 | [diff] [blame] | 561 | at least %h, %p, and %r (or alternatively %C) and be placed in a directory |
| 562 | that is not writable by other users. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 563 | This ensures that shared connections are uniquely identified. |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 564 | .It Cm ControlPersist |
| 565 | When used in conjunction with |
| 566 | .Cm ControlMaster , |
| 567 | specifies that the master connection should remain open |
| 568 | in the background (waiting for future client connections) |
| 569 | after the initial client connection has been closed. |
| 570 | If set to |
naddy@openbsd.org | a78c66d | 2020-01-21 12:40:04 +0000 | [diff] [blame] | 571 | .Cm no |
| 572 | (the default), |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 573 | then the master connection will not be placed into the background, |
| 574 | and will close as soon as the initial client connection is closed. |
| 575 | If set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 576 | .Cm yes |
| 577 | or 0, |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 578 | then the master connection will remain in the background indefinitely |
| 579 | (until killed or closed via a mechanism such as the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 580 | .Qq ssh -O exit ) . |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 581 | If set to a time in seconds, or a time in any of the formats documented in |
| 582 | .Xr sshd_config 5 , |
| 583 | then the backgrounded master connection will automatically terminate |
| 584 | after it has remained idle (with no client connections) for the |
| 585 | specified time. |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 586 | .It Cm DynamicForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 587 | Specifies that a TCP port on the local machine be forwarded |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 588 | over the secure channel, and the application |
| 589 | protocol is then used to determine where to connect to from the |
| 590 | remote machine. |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 591 | .Pp |
| 592 | The argument must be |
| 593 | .Sm off |
| 594 | .Oo Ar bind_address : Oc Ar port . |
| 595 | .Sm on |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 596 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 597 | By default, the local port is bound in accordance with the |
| 598 | .Cm GatewayPorts |
| 599 | setting. |
| 600 | However, an explicit |
| 601 | .Ar bind_address |
| 602 | may be used to bind the connection to a specific address. |
| 603 | The |
| 604 | .Ar bind_address |
| 605 | of |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 606 | .Cm localhost |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 607 | indicates that the listening port be bound for local use only, while an |
| 608 | empty address or |
| 609 | .Sq * |
| 610 | indicates that the port should be available from all interfaces. |
| 611 | .Pp |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 612 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 613 | .Xr ssh 1 |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 614 | will act as a SOCKS server. |
| 615 | Multiple forwardings may be specified, and |
| 616 | additional forwardings can be given on the command line. |
| 617 | Only the superuser can forward privileged ports. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 618 | .It Cm EnableSSHKeysign |
| 619 | Setting this option to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 620 | .Cm yes |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 621 | in the global client configuration file |
| 622 | .Pa /etc/ssh/ssh_config |
| 623 | enables the use of the helper program |
| 624 | .Xr ssh-keysign 8 |
| 625 | during |
| 626 | .Cm HostbasedAuthentication . |
| 627 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 628 | .Cm yes |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 629 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 630 | .Cm no |
| 631 | (the default). |
Darren Tucker | f132c67 | 2003-10-15 15:58:18 +1000 | [diff] [blame] | 632 | This option should be placed in the non-hostspecific section. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 633 | See |
| 634 | .Xr ssh-keysign 8 |
| 635 | for more information. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 636 | .It Cm EscapeChar |
| 637 | Sets the escape character (default: |
| 638 | .Ql ~ ) . |
| 639 | The escape character can also |
| 640 | be set on the command line. |
| 641 | The argument should be a single character, |
| 642 | .Ql ^ |
| 643 | followed by a letter, or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 644 | .Cm none |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 645 | to disable the escape |
| 646 | character entirely (making the connection transparent for binary |
| 647 | data). |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 648 | .It Cm ExitOnForwardFailure |
| 649 | Specifies whether |
| 650 | .Xr ssh 1 |
| 651 | should terminate the connection if it cannot set up all requested |
djm@openbsd.org | a954cdb | 2015-09-04 04:47:50 +0000 | [diff] [blame] | 652 | dynamic, tunnel, local, and remote port forwardings, (e.g.\& |
jmc@openbsd.org | 5245bc1 | 2015-09-04 06:40:45 +0000 | [diff] [blame] | 653 | if either end is unable to bind and listen on a specified port). |
djm@openbsd.org | a954cdb | 2015-09-04 04:47:50 +0000 | [diff] [blame] | 654 | Note that |
| 655 | .Cm ExitOnForwardFailure |
| 656 | does not apply to connections made over port forwardings and will not, |
| 657 | for example, cause |
| 658 | .Xr ssh 1 |
| 659 | to exit if TCP connections to the ultimate forwarding destination fail. |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 660 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 661 | .Cm yes |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 662 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 663 | .Cm no |
| 664 | (the default). |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 665 | .It Cm FingerprintHash |
| 666 | Specifies the hash algorithm used when displaying key fingerprints. |
| 667 | Valid options are: |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 668 | .Cm md5 |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 669 | and |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 670 | .Cm sha256 |
| 671 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 672 | .It Cm ForwardAgent |
| 673 | Specifies whether the connection to the authentication agent (if any) |
| 674 | will be forwarded to the remote machine. |
djm@openbsd.org | 40be78f | 2019-12-21 02:19:13 +0000 | [diff] [blame] | 675 | The argument may be |
| 676 | .Cm yes , |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 677 | .Cm no |
djm@openbsd.org | 40be78f | 2019-12-21 02:19:13 +0000 | [diff] [blame] | 678 | (the default), |
| 679 | an explicit path to an agent socket or the name of an environment variable |
| 680 | (beginning with |
| 681 | .Sq $ ) |
| 682 | in which to find the path. |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 683 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 684 | Agent forwarding should be enabled with caution. |
| 685 | Users with the ability to bypass file permissions on the remote host |
| 686 | (for the agent's Unix-domain socket) |
| 687 | can access the local agent through the forwarded connection. |
| 688 | An attacker cannot obtain key material from the agent, |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 689 | however they can perform operations on the keys that enable them to |
| 690 | authenticate using the identities loaded into the agent. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 691 | .It Cm ForwardX11 |
| 692 | Specifies whether X11 connections will be automatically redirected |
| 693 | over the secure channel and |
| 694 | .Ev DISPLAY |
| 695 | set. |
| 696 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 697 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 698 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 699 | .Cm no |
| 700 | (the default). |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 701 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 702 | X11 forwarding should be enabled with caution. |
| 703 | Users with the ability to bypass file permissions on the remote host |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 704 | (for the user's X11 authorization database) |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 705 | can access the local X11 display through the forwarded connection. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 706 | An attacker may then be able to perform activities such as keystroke monitoring |
| 707 | if the |
| 708 | .Cm ForwardX11Trusted |
| 709 | option is also enabled. |
Damien Miller | 1ab6a51 | 2010-06-26 10:02:24 +1000 | [diff] [blame] | 710 | .It Cm ForwardX11Timeout |
Damien Miller | cede1db | 2010-07-02 13:33:48 +1000 | [diff] [blame] | 711 | Specify a timeout for untrusted X11 forwarding |
| 712 | using the format described in the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 713 | .Sx TIME FORMATS |
| 714 | section of |
Damien Miller | 1ab6a51 | 2010-06-26 10:02:24 +1000 | [diff] [blame] | 715 | .Xr sshd_config 5 . |
| 716 | X11 connections received by |
| 717 | .Xr ssh 1 |
| 718 | after this time will be refused. |
djm@openbsd.org | b5e412a | 2018-09-21 12:46:22 +0000 | [diff] [blame] | 719 | Setting |
| 720 | .Cm ForwardX11Timeout |
| 721 | to zero will disable the timeout and permit X11 forwarding for the life |
| 722 | of the connection. |
Damien Miller | 1ab6a51 | 2010-06-26 10:02:24 +1000 | [diff] [blame] | 723 | The default is to disable untrusted X11 forwarding after twenty minutes has |
| 724 | elapsed. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 725 | .It Cm ForwardX11Trusted |
Darren Tucker | dcf6ec4 | 2004-05-13 13:03:56 +1000 | [diff] [blame] | 726 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 727 | .Cm yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 728 | remote X11 clients will have full access to the original X11 display. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 729 | .Pp |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 730 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 731 | .Cm no |
| 732 | (the default), |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 733 | remote X11 clients will be considered untrusted and prevented |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 734 | from stealing or tampering with data belonging to trusted X11 |
| 735 | clients. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 736 | Furthermore, the |
| 737 | .Xr xauth 1 |
| 738 | token used for the session will be set to expire after 20 minutes. |
| 739 | Remote clients will be refused access after this time. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 740 | .Pp |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 741 | See the X11 SECURITY extension specification for full details on |
| 742 | the restrictions imposed on untrusted clients. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 743 | .It Cm GatewayPorts |
| 744 | Specifies whether remote hosts are allowed to connect to local |
| 745 | forwarded ports. |
| 746 | By default, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 747 | .Xr ssh 1 |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 748 | binds local port forwardings to the loopback address. |
| 749 | This prevents other remote hosts from connecting to forwarded ports. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 750 | .Cm GatewayPorts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 751 | can be used to specify that ssh |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 752 | should bind local port forwardings to the wildcard address, |
| 753 | thus allowing remote hosts to connect to forwarded ports. |
| 754 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 755 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 756 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 757 | .Cm no |
| 758 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 759 | .It Cm GlobalKnownHostsFile |
Damien Miller | 295ee63 | 2011-05-29 21:42:31 +1000 | [diff] [blame] | 760 | Specifies one or more files to use for the global |
| 761 | host key database, separated by whitespace. |
| 762 | The default is |
| 763 | .Pa /etc/ssh/ssh_known_hosts , |
| 764 | .Pa /etc/ssh/ssh_known_hosts2 . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 765 | .It Cm GSSAPIAuthentication |
Damien Miller | baafb98 | 2003-12-17 16:32:23 +1100 | [diff] [blame] | 766 | Specifies whether user authentication based on GSSAPI is allowed. |
Damien Miller | c2b9827 | 2003-09-03 12:13:30 +1000 | [diff] [blame] | 767 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 768 | .Cm no . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 769 | .It Cm GSSAPIDelegateCredentials |
| 770 | Forward (delegate) credentials to the server. |
| 771 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 772 | .Cm no . |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 773 | .It Cm HashKnownHosts |
| 774 | Indicates that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 775 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 776 | should hash host names and addresses when they are added to |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 777 | .Pa ~/.ssh/known_hosts . |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 778 | These hashed names may be used normally by |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 779 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 780 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 781 | .Xr sshd 8 , |
djm@openbsd.org | 3432b6e | 2020-01-25 07:02:51 +0000 | [diff] [blame] | 782 | but they do not visually reveal identifying information if the |
| 783 | file's contents are disclosed. |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 784 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 785 | .Cm no . |
Damien Miller | 858bb7d | 2006-08-05 11:34:51 +1000 | [diff] [blame] | 786 | Note that existing names and addresses in known hosts files |
| 787 | will not be converted automatically, |
| 788 | but may be manually hashed using |
Damien Miller | 4b42d7f | 2005-03-01 21:48:35 +1100 | [diff] [blame] | 789 | .Xr ssh-keygen 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 790 | .It Cm HostbasedAuthentication |
| 791 | Specifies whether to try rhosts based authentication with public key |
| 792 | authentication. |
| 793 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 794 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 795 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 796 | .Cm no |
| 797 | (the default). |
djm@openbsd.org | 46347ed | 2015-01-30 11:43:14 +0000 | [diff] [blame] | 798 | .It Cm HostbasedKeyTypes |
| 799 | Specifies the key types that will be used for hostbased authentication |
djm@openbsd.org | 312d2f2 | 2018-07-04 13:49:31 +0000 | [diff] [blame] | 800 | as a comma-separated list of patterns. |
naddy@openbsd.org | 4f9d75f | 2019-09-04 20:31:15 +0000 | [diff] [blame] | 801 | Alternately if the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 802 | .Sq + |
| 803 | character, then the specified key types will be appended to the default set |
| 804 | instead of replacing them. |
naddy@openbsd.org | 4f9d75f | 2019-09-04 20:31:15 +0000 | [diff] [blame] | 805 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 806 | .Sq - |
| 807 | character, then the specified key types (including wildcards) will be removed |
| 808 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 809 | If the specified list begins with a |
| 810 | .Sq ^ |
| 811 | character, then the specified key types will be placed at the head of the |
| 812 | default set. |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 813 | The default for this option is: |
| 814 | .Bd -literal -offset 3n |
| 815 | ecdsa-sha2-nistp256-cert-v01@openssh.com, |
| 816 | ecdsa-sha2-nistp384-cert-v01@openssh.com, |
| 817 | ecdsa-sha2-nistp521-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 818 | sk-ecdsa-sha2-nistp256-cert-v01@openssh.com, |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 819 | ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 820 | sk-ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 821 | rsa-sha2-512-cert-v01@openssh.com, |
| 822 | rsa-sha2-256-cert-v01@openssh.com, |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 823 | ssh-rsa-cert-v01@openssh.com, |
| 824 | ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 825 | sk-ecdsa-sha2-nistp256@openssh.com, |
| 826 | ssh-ed25519,sk-ssh-ed25519@openssh.com, |
| 827 | rsa-sha2-512,rsa-sha2-256,ssh-rsa |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 828 | .Ed |
| 829 | .Pp |
djm@openbsd.org | 46347ed | 2015-01-30 11:43:14 +0000 | [diff] [blame] | 830 | The |
| 831 | .Fl Q |
| 832 | option of |
| 833 | .Xr ssh 1 |
| 834 | may be used to list supported key types. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 835 | .It Cm HostKeyAlgorithms |
jmc@openbsd.org | a685ae8 | 2016-02-17 07:38:19 +0000 | [diff] [blame] | 836 | Specifies the host key algorithms |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 837 | that the client wants to use in order of preference. |
naddy@openbsd.org | 4f9d75f | 2019-09-04 20:31:15 +0000 | [diff] [blame] | 838 | Alternately if the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 839 | .Sq + |
| 840 | character, then the specified key types will be appended to the default set |
| 841 | instead of replacing them. |
naddy@openbsd.org | 4f9d75f | 2019-09-04 20:31:15 +0000 | [diff] [blame] | 842 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 843 | .Sq - |
| 844 | character, then the specified key types (including wildcards) will be removed |
| 845 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 846 | If the specified list begins with a |
| 847 | .Sq ^ |
| 848 | character, then the specified key types will be placed at the head of the |
| 849 | default set. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 850 | The default for this option is: |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 851 | .Bd -literal -offset 3n |
| 852 | ecdsa-sha2-nistp256-cert-v01@openssh.com, |
| 853 | ecdsa-sha2-nistp384-cert-v01@openssh.com, |
| 854 | ecdsa-sha2-nistp521-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 855 | sk-ecdsa-sha2-nistp256-cert-v01@openssh.com, |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame] | 856 | ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 857 | sk-ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 858 | rsa-sha2-512-cert-v01@openssh.com, |
| 859 | rsa-sha2-256-cert-v01@openssh.com, |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 860 | ssh-rsa-cert-v01@openssh.com, |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 861 | ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 862 | sk-ecdsa-sha2-nistp256@openssh.com, |
| 863 | ssh-ed25519,sk-ssh-ed25519@openssh.com, |
| 864 | rsa-sha2-512,rsa-sha2-256,ssh-rsa |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 865 | .Ed |
Damien Miller | d925dcd | 2010-12-01 12:21:51 +1100 | [diff] [blame] | 866 | .Pp |
| 867 | If hostkeys are known for the destination host then this default is modified |
| 868 | to prefer their algorithms. |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 869 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 870 | The list of available key types may also be obtained using |
dtucker@openbsd.org | d4d9e1d | 2020-02-07 03:54:44 +0000 | [diff] [blame] | 871 | .Qq ssh -Q HostKeyAlgorithms . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 872 | .It Cm HostKeyAlias |
| 873 | Specifies an alias that should be used instead of the |
| 874 | real host name when looking up or saving the host key |
djm@openbsd.org | 6f8ca3b | 2017-06-24 05:35:05 +0000 | [diff] [blame] | 875 | in the host key database files and when validating host certificates. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 876 | This option is useful for tunneling SSH connections |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 877 | or for multiple servers running on a single host. |
jmc@openbsd.org | 76af9c5 | 2019-06-12 05:53:21 +0000 | [diff] [blame] | 878 | .It Cm Hostname |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 879 | Specifies the real host name to log into. |
| 880 | This can be used to specify nicknames or abbreviations for hosts. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 881 | Arguments to |
jmc@openbsd.org | 76af9c5 | 2019-06-12 05:53:21 +0000 | [diff] [blame] | 882 | .Cm Hostname |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 883 | accept the tokens described in the |
| 884 | .Sx TOKENS |
| 885 | section. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 886 | Numeric IP addresses are also permitted (both on the command line and in |
jmc@openbsd.org | 76af9c5 | 2019-06-12 05:53:21 +0000 | [diff] [blame] | 887 | .Cm Hostname |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 888 | specifications). |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 889 | The default is the name given on the command line. |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 890 | .It Cm IdentitiesOnly |
| 891 | Specifies that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 892 | .Xr ssh 1 |
djm@openbsd.org | 7047d5a | 2019-09-13 04:52:34 +0000 | [diff] [blame] | 893 | should only use the configured authentication identity and certificate files |
| 894 | (either the default files, or those explicitly configured in the |
Damien Miller | 1a81258 | 2004-04-20 20:13:32 +1000 | [diff] [blame] | 895 | .Nm |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 896 | files |
| 897 | or passed on the |
| 898 | .Xr ssh 1 |
djm@openbsd.org | 7047d5a | 2019-09-13 04:52:34 +0000 | [diff] [blame] | 899 | command-line), |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 900 | even if |
| 901 | .Xr ssh-agent 1 |
Damien Miller | cb6b68b | 2012-12-03 09:49:52 +1100 | [diff] [blame] | 902 | or a |
| 903 | .Cm PKCS11Provider |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 904 | or |
| 905 | .Cm SecurityKeyProvider |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 906 | offers more identities. |
| 907 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 908 | .Cm yes |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 909 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 910 | .Cm no |
| 911 | (the default). |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 912 | This option is intended for situations where ssh-agent |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 913 | offers many different identities. |
markus@openbsd.org | b02ad1c | 2016-05-04 12:21:53 +0000 | [diff] [blame] | 914 | .It Cm IdentityAgent |
| 915 | Specifies the |
| 916 | .Ux Ns -domain |
| 917 | socket used to communicate with the authentication agent. |
| 918 | .Pp |
| 919 | This option overrides the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 920 | .Ev SSH_AUTH_SOCK |
markus@openbsd.org | b02ad1c | 2016-05-04 12:21:53 +0000 | [diff] [blame] | 921 | environment variable and can be used to select a specific agent. |
| 922 | Setting the socket name to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 923 | .Cm none |
markus@openbsd.org | b02ad1c | 2016-05-04 12:21:53 +0000 | [diff] [blame] | 924 | disables the use of an authentication agent. |
markus@openbsd.org | 1a75d14 | 2016-05-04 14:29:58 +0000 | [diff] [blame] | 925 | If the string |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 926 | .Qq SSH_AUTH_SOCK |
markus@openbsd.org | 1a75d14 | 2016-05-04 14:29:58 +0000 | [diff] [blame] | 927 | is specified, the location of the socket will be read from the |
| 928 | .Ev SSH_AUTH_SOCK |
| 929 | environment variable. |
djm@openbsd.org | 5eff5b8 | 2018-10-03 06:38:35 +0000 | [diff] [blame] | 930 | Otherwise if the specified value begins with a |
| 931 | .Sq $ |
| 932 | character, then it will be treated as an environment variable containing |
| 933 | the location of the socket. |
markus@openbsd.org | b02ad1c | 2016-05-04 12:21:53 +0000 | [diff] [blame] | 934 | .Pp |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 935 | Arguments to |
| 936 | .Cm IdentityAgent |
| 937 | may use the tilde syntax to refer to a user's home directory |
| 938 | or the tokens described in the |
| 939 | .Sx TOKENS |
| 940 | section. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 941 | .It Cm IdentityFile |
naddy@openbsd.org | 141df48 | 2019-12-21 20:22:34 +0000 | [diff] [blame] | 942 | Specifies a file from which the user's DSA, ECDSA, authenticator-hosted ECDSA, |
| 943 | Ed25519, authenticator-hosted Ed25519 or RSA authentication identity is read. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 944 | The default is |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 945 | .Pa ~/.ssh/id_dsa , |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame] | 946 | .Pa ~/.ssh/id_ecdsa , |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 947 | .Pa ~/.ssh/id_ecdsa_sk , |
naddy@openbsd.org | f0edda8 | 2019-11-18 23:16:49 +0000 | [diff] [blame] | 948 | .Pa ~/.ssh/id_ed25519 , |
| 949 | .Pa ~/.ssh/id_ed25519_sk |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 950 | and |
djm@openbsd.org | 788ac79 | 2017-04-30 23:18:22 +0000 | [diff] [blame] | 951 | .Pa ~/.ssh/id_rsa . |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 952 | Additionally, any identities represented by the authentication agent |
Damien Miller | 7f2b438 | 2013-07-18 16:10:29 +1000 | [diff] [blame] | 953 | will be used for authentication unless |
| 954 | .Cm IdentitiesOnly |
| 955 | is set. |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 956 | If no certificates have been explicitly specified by |
| 957 | .Cm CertificateFile , |
Damien Miller | 5059d8d | 2010-03-05 21:31:11 +1100 | [diff] [blame] | 958 | .Xr ssh 1 |
| 959 | will try to load certificate information from the filename obtained by |
| 960 | appending |
| 961 | .Pa -cert.pub |
| 962 | to the path of a specified |
| 963 | .Cm IdentityFile . |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 964 | .Pp |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 965 | Arguments to |
| 966 | .Cm IdentityFile |
| 967 | may use the tilde syntax to refer to a user's home directory |
| 968 | or the tokens described in the |
| 969 | .Sx TOKENS |
| 970 | section. |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 971 | .Pp |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 972 | It is possible to have |
| 973 | multiple identity files specified in configuration files; all these |
| 974 | identities will be tried in sequence. |
Damien Miller | 6029e07 | 2011-06-20 14:22:49 +1000 | [diff] [blame] | 975 | Multiple |
| 976 | .Cm IdentityFile |
| 977 | directives will add to the list of identities tried (this behaviour |
| 978 | differs from that of other configuration directives). |
Damien Miller | 7f2b438 | 2013-07-18 16:10:29 +1000 | [diff] [blame] | 979 | .Pp |
| 980 | .Cm IdentityFile |
| 981 | may be used in conjunction with |
| 982 | .Cm IdentitiesOnly |
| 983 | to select which identities in an agent are offered during authentication. |
djm@openbsd.org | 4e44a79 | 2015-09-24 06:15:11 +0000 | [diff] [blame] | 984 | .Cm IdentityFile |
| 985 | may also be used in conjunction with |
| 986 | .Cm CertificateFile |
| 987 | in order to provide any certificate also needed for authentication with |
| 988 | the identity. |
Darren Tucker | 63e0df2 | 2013-05-16 20:30:31 +1000 | [diff] [blame] | 989 | .It Cm IgnoreUnknown |
| 990 | Specifies a pattern-list of unknown options to be ignored if they are |
| 991 | encountered in configuration parsing. |
| 992 | This may be used to suppress errors if |
| 993 | .Nm |
| 994 | contains options that are unrecognised by |
| 995 | .Xr ssh 1 . |
| 996 | It is recommended that |
| 997 | .Cm IgnoreUnknown |
| 998 | be listed early in the configuration file as it will not be applied |
| 999 | to unknown options that appear before it. |
djm@openbsd.org | dc7990b | 2016-04-15 00:30:19 +0000 | [diff] [blame] | 1000 | .It Cm Include |
| 1001 | Include the specified configuration file(s). |
jmc@openbsd.org | 6aaabc2 | 2016-04-17 14:34:46 +0000 | [diff] [blame] | 1002 | Multiple pathnames may be specified and each pathname may contain |
kn@openbsd.org | ddf1b79 | 2018-07-23 19:02:49 +0000 | [diff] [blame] | 1003 | .Xr glob 7 |
djm@openbsd.org | dc7990b | 2016-04-15 00:30:19 +0000 | [diff] [blame] | 1004 | wildcards and, for user configurations, shell-like |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1005 | .Sq ~ |
djm@openbsd.org | dc7990b | 2016-04-15 00:30:19 +0000 | [diff] [blame] | 1006 | references to user home directories. |
| 1007 | Files without absolute paths are assumed to be in |
| 1008 | .Pa ~/.ssh |
jmc@openbsd.org | 6aaabc2 | 2016-04-17 14:34:46 +0000 | [diff] [blame] | 1009 | if included in a user configuration file or |
djm@openbsd.org | dc7990b | 2016-04-15 00:30:19 +0000 | [diff] [blame] | 1010 | .Pa /etc/ssh |
| 1011 | if included from the system configuration file. |
| 1012 | .Cm Include |
| 1013 | directive may appear inside a |
| 1014 | .Cm Match |
| 1015 | or |
| 1016 | .Cm Host |
| 1017 | block |
| 1018 | to perform conditional inclusion. |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 1019 | .It Cm IPQoS |
| 1020 | Specifies the IPv4 type-of-service or DSCP class for connections. |
| 1021 | Accepted values are |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1022 | .Cm af11 , |
| 1023 | .Cm af12 , |
| 1024 | .Cm af13 , |
| 1025 | .Cm af21 , |
| 1026 | .Cm af22 , |
| 1027 | .Cm af23 , |
| 1028 | .Cm af31 , |
| 1029 | .Cm af32 , |
| 1030 | .Cm af33 , |
| 1031 | .Cm af41 , |
| 1032 | .Cm af42 , |
| 1033 | .Cm af43 , |
| 1034 | .Cm cs0 , |
| 1035 | .Cm cs1 , |
| 1036 | .Cm cs2 , |
| 1037 | .Cm cs3 , |
| 1038 | .Cm cs4 , |
| 1039 | .Cm cs5 , |
| 1040 | .Cm cs6 , |
| 1041 | .Cm cs7 , |
| 1042 | .Cm ef , |
djm@openbsd.org | 4594c76 | 2020-01-28 01:49:36 +0000 | [diff] [blame] | 1043 | .Cm le , |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1044 | .Cm lowdelay , |
| 1045 | .Cm throughput , |
| 1046 | .Cm reliability , |
djm@openbsd.org | 51676ec | 2017-07-23 23:37:02 +0000 | [diff] [blame] | 1047 | a numeric value, or |
| 1048 | .Cm none |
| 1049 | to use the operating system default. |
Damien Miller | 928362d | 2010-12-26 14:26:45 +1100 | [diff] [blame] | 1050 | This option may take one or two arguments, separated by whitespace. |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 1051 | If one argument is specified, it is used as the packet class unconditionally. |
| 1052 | If two values are specified, the first is automatically selected for |
| 1053 | interactive sessions and the second for non-interactive sessions. |
| 1054 | The default is |
job@openbsd.org | 5ee8448 | 2018-04-04 15:12:17 +0000 | [diff] [blame] | 1055 | .Cm af21 |
jmc@openbsd.org | 8368571 | 2018-04-07 13:50:10 +0000 | [diff] [blame] | 1056 | (Low-Latency Data) |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 1057 | for interactive sessions and |
job@openbsd.org | 5ee8448 | 2018-04-04 15:12:17 +0000 | [diff] [blame] | 1058 | .Cm cs1 |
jmc@openbsd.org | 8368571 | 2018-04-07 13:50:10 +0000 | [diff] [blame] | 1059 | (Lower Effort) |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 1060 | for non-interactive sessions. |
Damien Miller | cfb606c | 2007-10-26 14:24:48 +1000 | [diff] [blame] | 1061 | .It Cm KbdInteractiveAuthentication |
| 1062 | Specifies whether to use keyboard-interactive authentication. |
| 1063 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1064 | .Cm yes |
| 1065 | (the default) |
Damien Miller | cfb606c | 2007-10-26 14:24:48 +1000 | [diff] [blame] | 1066 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1067 | .Cm no . |
Darren Tucker | 636ca90 | 2004-11-05 20:22:00 +1100 | [diff] [blame] | 1068 | .It Cm KbdInteractiveDevices |
| 1069 | Specifies the list of methods to use in keyboard-interactive authentication. |
| 1070 | Multiple method names must be comma-separated. |
| 1071 | The default is to use the server specified list. |
Damien Miller | 9cfbaec | 2006-03-15 11:57:55 +1100 | [diff] [blame] | 1072 | The methods available vary depending on what the server supports. |
| 1073 | For an OpenSSH server, |
| 1074 | it may be zero or more of: |
Damien Miller | 87f08be | 2018-07-20 13:18:28 +1000 | [diff] [blame] | 1075 | .Cm bsdauth |
Damien Miller | 9cfbaec | 2006-03-15 11:57:55 +1100 | [diff] [blame] | 1076 | and |
Damien Miller | 87f08be | 2018-07-20 13:18:28 +1000 | [diff] [blame] | 1077 | .Cm pam . |
Damien Miller | d5f62bf | 2010-09-24 22:11:14 +1000 | [diff] [blame] | 1078 | .It Cm KexAlgorithms |
| 1079 | Specifies the available KEX (Key Exchange) algorithms. |
| 1080 | Multiple algorithms must be comma-separated. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1081 | If the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 1082 | .Sq + |
| 1083 | character, then the specified methods will be appended to the default set |
| 1084 | instead of replacing them. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1085 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 1086 | .Sq - |
| 1087 | character, then the specified methods (including wildcards) will be removed |
| 1088 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 1089 | If the specified list begins with a |
| 1090 | .Sq ^ |
| 1091 | character, then the specified methods will be placed at the head of the |
| 1092 | default set. |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 1093 | The default is: |
| 1094 | .Bd -literal -offset indent |
djm@openbsd.org | 16277fc | 2016-09-22 17:55:13 +0000 | [diff] [blame] | 1095 | curve25519-sha256,curve25519-sha256@libssh.org, |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 1096 | ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521, |
| 1097 | diffie-hellman-group-exchange-sha256, |
djm@openbsd.org | 680321f | 2018-02-16 02:40:45 +0000 | [diff] [blame] | 1098 | diffie-hellman-group16-sha512, |
| 1099 | diffie-hellman-group18-sha512, |
tedu@openbsd.org | 0b81343 | 2020-01-25 07:09:14 +0000 | [diff] [blame] | 1100 | diffie-hellman-group14-sha256 |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 1101 | .Ed |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 1102 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1103 | The list of available key exchange algorithms may also be obtained using |
| 1104 | .Qq ssh -Q kex . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1105 | .It Cm LocalCommand |
| 1106 | Specifies a command to execute on the local machine after successfully |
| 1107 | connecting to the server. |
| 1108 | 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] | 1109 | the user's shell. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1110 | Arguments to |
| 1111 | .Cm LocalCommand |
| 1112 | accept the tokens described in the |
| 1113 | .Sx TOKENS |
| 1114 | section. |
Darren Tucker | 78be8c5 | 2010-01-08 17:05:59 +1100 | [diff] [blame] | 1115 | .Pp |
| 1116 | The command is run synchronously and does not have access to the |
| 1117 | session of the |
| 1118 | .Xr ssh 1 |
| 1119 | that spawned it. |
| 1120 | It should not be used for interactive commands. |
| 1121 | .Pp |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1122 | This directive is ignored unless |
| 1123 | .Cm PermitLocalCommand |
| 1124 | has been enabled. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1125 | .It Cm LocalForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 1126 | Specifies that a TCP port on the local machine be forwarded over |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1127 | 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] | 1128 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1129 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1130 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1131 | .Sm on |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1132 | and the second argument must be |
| 1133 | .Ar host : Ns Ar hostport . |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 1134 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1135 | Multiple forwardings may be specified, and additional forwardings can be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1136 | given on the command line. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1137 | Only the superuser can forward privileged ports. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1138 | By default, the local port is bound in accordance with the |
| 1139 | .Cm GatewayPorts |
| 1140 | setting. |
| 1141 | However, an explicit |
| 1142 | .Ar bind_address |
| 1143 | may be used to bind the connection to a specific address. |
| 1144 | The |
| 1145 | .Ar bind_address |
| 1146 | of |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1147 | .Cm localhost |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1148 | indicates that the listening port be bound for local use only, while an |
| 1149 | empty address or |
| 1150 | .Sq * |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1151 | indicates that the port should be available from all interfaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1152 | .It Cm LogLevel |
| 1153 | Gives the verbosity level that is used when logging messages from |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1154 | .Xr ssh 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1155 | The possible values are: |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1156 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 1157 | The default is INFO. |
| 1158 | DEBUG and DEBUG1 are equivalent. |
| 1159 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1160 | .It Cm MACs |
| 1161 | Specifies the MAC (message authentication code) algorithms |
| 1162 | in order of preference. |
jmc@openbsd.org | a685ae8 | 2016-02-17 07:38:19 +0000 | [diff] [blame] | 1163 | The MAC algorithm is used for data integrity protection. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1164 | Multiple algorithms must be comma-separated. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1165 | If the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 1166 | .Sq + |
| 1167 | character, then the specified algorithms will be appended to the default set |
| 1168 | instead of replacing them. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1169 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 1170 | .Sq - |
| 1171 | character, then the specified algorithms (including wildcards) will be removed |
| 1172 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 1173 | If the specified list begins with a |
| 1174 | .Sq ^ |
| 1175 | character, then the specified algorithms will be placed at the head of the |
| 1176 | default set. |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 1177 | .Pp |
Damien Miller | af43a7a | 2012-12-12 10:46:31 +1100 | [diff] [blame] | 1178 | The algorithms that contain |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1179 | .Qq -etm |
Damien Miller | af43a7a | 2012-12-12 10:46:31 +1100 | [diff] [blame] | 1180 | calculate the MAC after encryption (encrypt-then-mac). |
| 1181 | These are considered safer and their use recommended. |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 1182 | .Pp |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1183 | The default is: |
Damien Miller | 5e7c30b | 2007-06-11 14:06:32 +1000 | [diff] [blame] | 1184 | .Bd -literal -offset indent |
Damien Miller | af43a7a | 2012-12-12 10:46:31 +1100 | [diff] [blame] | 1185 | umac-64-etm@openssh.com,umac-128-etm@openssh.com, |
| 1186 | hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com, |
djm@openbsd.org | e4c918a | 2016-02-11 02:56:32 +0000 | [diff] [blame] | 1187 | hmac-sha1-etm@openssh.com, |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 1188 | umac-64@openssh.com,umac-128@openssh.com, |
djm@openbsd.org | e4c918a | 2016-02-11 02:56:32 +0000 | [diff] [blame] | 1189 | hmac-sha2-256,hmac-sha2-512,hmac-sha1 |
Damien Miller | 5e7c30b | 2007-06-11 14:06:32 +1000 | [diff] [blame] | 1190 | .Ed |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 1191 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1192 | The list of available MAC algorithms may also be obtained using |
| 1193 | .Qq ssh -Q mac . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1194 | .It Cm NoHostAuthenticationForLocalhost |
djm@openbsd.org | 4f011da | 2018-02-10 06:40:28 +0000 | [diff] [blame] | 1195 | Disable host authentication for localhost (loopback addresses). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1196 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1197 | .Cm yes |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1198 | or |
jmc@openbsd.org | 78142e3 | 2017-02-27 14:30:33 +0000 | [diff] [blame] | 1199 | .Cm no |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1200 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1201 | .It Cm NumberOfPasswordPrompts |
| 1202 | Specifies the number of password prompts before giving up. |
| 1203 | The argument to this keyword must be an integer. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1204 | The default is 3. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1205 | .It Cm PasswordAuthentication |
| 1206 | Specifies whether to use password authentication. |
| 1207 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1208 | .Cm yes |
| 1209 | (the default) |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1210 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1211 | .Cm no . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1212 | .It Cm PermitLocalCommand |
| 1213 | Allow local command execution via the |
| 1214 | .Ic LocalCommand |
| 1215 | option or using the |
Damien Miller | 4b2319f | 2005-12-13 19:30:27 +1100 | [diff] [blame] | 1216 | .Ic !\& Ns Ar command |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1217 | escape sequence in |
| 1218 | .Xr ssh 1 . |
| 1219 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1220 | .Cm yes |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1221 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1222 | .Cm no |
| 1223 | (the default). |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 1224 | .It Cm PKCS11Provider |
djm@openbsd.org | de817e9 | 2019-03-01 02:16:47 +0000 | [diff] [blame] | 1225 | Specifies which PKCS#11 provider to use or |
| 1226 | .Cm none |
| 1227 | to indicate that no provider should be used (the default). |
| 1228 | The argument to this keyword is a path to the PKCS#11 shared library |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 1229 | .Xr ssh 1 |
djm@openbsd.org | de817e9 | 2019-03-01 02:16:47 +0000 | [diff] [blame] | 1230 | should use to communicate with a PKCS#11 token providing keys for user |
| 1231 | authentication. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1232 | .It Cm Port |
| 1233 | Specifies the port number to connect on the remote host. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1234 | The default is 22. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1235 | .It Cm PreferredAuthentications |
jmc@openbsd.org | a685ae8 | 2016-02-17 07:38:19 +0000 | [diff] [blame] | 1236 | Specifies the order in which the client should try authentication methods. |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 1237 | This allows a client to prefer one method (e.g.\& |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1238 | .Cm keyboard-interactive ) |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 1239 | over another method (e.g.\& |
Damien Miller | 544378d | 2010-04-16 15:52:24 +1000 | [diff] [blame] | 1240 | .Cm password ) . |
| 1241 | The default is: |
| 1242 | .Bd -literal -offset indent |
| 1243 | gssapi-with-mic,hostbased,publickey, |
| 1244 | keyboard-interactive,password |
| 1245 | .Ed |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1246 | .It Cm ProxyCommand |
| 1247 | Specifies the command to use to connect to the server. |
| 1248 | The command |
Damien Miller | 079bac2 | 2014-07-09 13:06:25 +1000 | [diff] [blame] | 1249 | string extends to the end of the line, and is executed |
| 1250 | using the user's shell |
| 1251 | .Ql exec |
| 1252 | directive to avoid a lingering shell process. |
| 1253 | .Pp |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1254 | Arguments to |
| 1255 | .Cm ProxyCommand |
| 1256 | accept the tokens described in the |
| 1257 | .Sx TOKENS |
| 1258 | section. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1259 | The command can be basically anything, |
| 1260 | and should read from its standard input and write to its standard output. |
| 1261 | It should eventually connect an |
| 1262 | .Xr sshd 8 |
| 1263 | server running on some machine, or execute |
| 1264 | .Ic sshd -i |
| 1265 | somewhere. |
| 1266 | Host key management will be done using the |
jmc@openbsd.org | 7349149 | 2019-06-12 11:31:50 +0000 | [diff] [blame] | 1267 | .Cm Hostname |
| 1268 | of the host being connected (defaulting to the name typed by the user). |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 1269 | Setting the command to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1270 | .Cm none |
Damien Miller | 9f1e33a | 2003-02-24 11:57:32 +1100 | [diff] [blame] | 1271 | disables this option entirely. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1272 | Note that |
| 1273 | .Cm CheckHostIP |
| 1274 | is not available for connects with a proxy command. |
| 1275 | .Pp |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 1276 | This directive is useful in conjunction with |
| 1277 | .Xr nc 1 |
| 1278 | and its proxy support. |
Damien Miller | dfec294 | 2005-05-26 12:14:32 +1000 | [diff] [blame] | 1279 | For example, the following directive would connect via an HTTP proxy at |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 1280 | 192.0.2.0: |
| 1281 | .Bd -literal -offset 3n |
| 1282 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p |
| 1283 | .Ed |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1284 | .It Cm ProxyJump |
millert@openbsd.org | 887669e | 2017-10-21 23:06:24 +0000 | [diff] [blame] | 1285 | Specifies one or more jump proxies as either |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1286 | .Xo |
| 1287 | .Sm off |
jmc@openbsd.org | e4eb7d9 | 2016-07-16 06:57:55 +0000 | [diff] [blame] | 1288 | .Op Ar user No @ |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1289 | .Ar host |
jmc@openbsd.org | e4eb7d9 | 2016-07-16 06:57:55 +0000 | [diff] [blame] | 1290 | .Op : Ns Ar port |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1291 | .Sm on |
millert@openbsd.org | 887669e | 2017-10-21 23:06:24 +0000 | [diff] [blame] | 1292 | or an ssh URI |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1293 | .Xc . |
djm@openbsd.org | 286f5a7 | 2016-07-22 03:35:11 +0000 | [diff] [blame] | 1294 | Multiple proxies may be separated by comma characters and will be visited |
djm@openbsd.org | f00211e | 2016-07-22 07:00:46 +0000 | [diff] [blame] | 1295 | sequentially. |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1296 | Setting this option will cause |
| 1297 | .Xr ssh 1 |
| 1298 | to connect to the target host by first making a |
| 1299 | .Xr ssh 1 |
| 1300 | connection to the specified |
| 1301 | .Cm ProxyJump |
| 1302 | host and then establishing a |
jmc@openbsd.org | e4eb7d9 | 2016-07-16 06:57:55 +0000 | [diff] [blame] | 1303 | TCP forwarding to the ultimate target from there. |
djm@openbsd.org | ed877ef | 2016-07-15 00:24:30 +0000 | [diff] [blame] | 1304 | .Pp |
| 1305 | Note that this option will compete with the |
| 1306 | .Cm ProxyCommand |
| 1307 | option - whichever is specified first will prevent later instances of the |
| 1308 | other from taking effect. |
djm@openbsd.org | 7a2cb18 | 2019-01-22 11:51:25 +0000 | [diff] [blame] | 1309 | .Pp |
| 1310 | Note also that the configuration for the destination host (either supplied |
| 1311 | via the command-line or the configuration file) is not generally applied |
| 1312 | to jump hosts. |
| 1313 | .Pa ~/.ssh/config |
| 1314 | should be used if specific configuration is required for jump hosts. |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1315 | .It Cm ProxyUseFdpass |
Damien Miller | f2f6c31 | 2013-08-21 02:44:58 +1000 | [diff] [blame] | 1316 | Specifies that |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1317 | .Cm ProxyCommand |
| 1318 | will pass a connected file descriptor back to |
Damien Miller | f2f6c31 | 2013-08-21 02:44:58 +1000 | [diff] [blame] | 1319 | .Xr ssh 1 |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1320 | instead of continuing to execute and pass data. |
| 1321 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1322 | .Cm no . |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 1323 | .It Cm PubkeyAcceptedKeyTypes |
| 1324 | Specifies the key types that will be used for public key authentication |
djm@openbsd.org | 312d2f2 | 2018-07-04 13:49:31 +0000 | [diff] [blame] | 1325 | as a comma-separated list of patterns. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1326 | If the specified list begins with a |
djm@openbsd.org | f9eca24 | 2015-07-30 00:01:34 +0000 | [diff] [blame] | 1327 | .Sq + |
| 1328 | character, then the key types after it will be appended to the default |
| 1329 | instead of replacing it. |
kn@openbsd.org | dc2ca58 | 2019-08-16 11:16:32 +0000 | [diff] [blame] | 1330 | If the specified list begins with a |
djm@openbsd.org | 68bc8cf | 2017-02-03 23:01:19 +0000 | [diff] [blame] | 1331 | .Sq - |
| 1332 | character, then the specified key types (including wildcards) will be removed |
| 1333 | from the default set instead of replacing them. |
naddy@openbsd.org | 91a2135 | 2019-09-06 14:45:34 +0000 | [diff] [blame] | 1334 | If the specified list begins with a |
| 1335 | .Sq ^ |
| 1336 | character, then the specified key types will be placed at the head of the |
| 1337 | default set. |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 1338 | The default for this option is: |
| 1339 | .Bd -literal -offset 3n |
| 1340 | ecdsa-sha2-nistp256-cert-v01@openssh.com, |
| 1341 | ecdsa-sha2-nistp384-cert-v01@openssh.com, |
| 1342 | ecdsa-sha2-nistp521-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 1343 | sk-ecdsa-sha2-nistp256-cert-v01@openssh.com, |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 1344 | ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 1345 | sk-ssh-ed25519-cert-v01@openssh.com, |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 1346 | rsa-sha2-512-cert-v01@openssh.com, |
| 1347 | rsa-sha2-256-cert-v01@openssh.com, |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 1348 | ssh-rsa-cert-v01@openssh.com, |
| 1349 | ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, |
naddy@openbsd.org | ae024b2 | 2019-12-19 15:09:30 +0000 | [diff] [blame] | 1350 | sk-ecdsa-sha2-nistp256@openssh.com, |
| 1351 | ssh-ed25519,sk-ssh-ed25519@openssh.com, |
| 1352 | rsa-sha2-512,rsa-sha2-256,ssh-rsa |
markus@openbsd.org | 3a1638d | 2015-07-10 06:21:53 +0000 | [diff] [blame] | 1353 | .Ed |
| 1354 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1355 | The list of available key types may also be obtained using |
dtucker@openbsd.org | d4d9e1d | 2020-02-07 03:54:44 +0000 | [diff] [blame] | 1356 | .Qq ssh -Q PubkeyAcceptedKeyTypes . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1357 | .It Cm PubkeyAuthentication |
| 1358 | Specifies whether to try public key authentication. |
| 1359 | The argument to this keyword must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1360 | .Cm yes |
| 1361 | (the default) |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1362 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1363 | .Cm no . |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1364 | .It Cm RekeyLimit |
| 1365 | Specifies the maximum amount of data that may be transmitted before the |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1366 | session key is renegotiated, optionally followed a maximum amount of |
| 1367 | time that may pass before the session key is renegotiated. |
| 1368 | The first argument is specified in bytes and may have a suffix of |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 1369 | .Sq K , |
| 1370 | .Sq M , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1371 | or |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 1372 | .Sq G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1373 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. |
| 1374 | The default is between |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1375 | .Sq 1G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1376 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1377 | .Sq 4G , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1378 | depending on the cipher. |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1379 | The optional second value is specified in seconds and may use any of the |
schwarze@openbsd.org | db7606d | 2019-05-14 12:47:17 +0000 | [diff] [blame] | 1380 | units documented in the TIME FORMATS section of |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1381 | .Xr sshd_config 5 . |
| 1382 | The default value for |
| 1383 | .Cm RekeyLimit |
| 1384 | is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1385 | .Cm default none , |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1386 | which means that rekeying is performed after the cipher's default amount |
| 1387 | of data has been sent or received and no time based rekeying is done. |
bluhm@openbsd.org | 1112b53 | 2017-05-30 18:58:37 +0000 | [diff] [blame] | 1388 | .It Cm RemoteCommand |
| 1389 | Specifies a command to execute on the remote machine after successfully |
| 1390 | connecting to the server. |
| 1391 | The command string extends to the end of the line, and is executed with |
| 1392 | the user's shell. |
jmc@openbsd.org | a3bb250 | 2017-05-30 19:38:17 +0000 | [diff] [blame] | 1393 | Arguments to |
| 1394 | .Cm RemoteCommand |
| 1395 | accept the tokens described in the |
| 1396 | .Sx TOKENS |
| 1397 | section. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1398 | .It Cm RemoteForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 1399 | Specifies that a TCP port on the remote machine be forwarded over |
markus@openbsd.org | 609d7a6 | 2017-09-21 19:16:53 +0000 | [diff] [blame] | 1400 | the secure channel. |
djm@openbsd.org | 001aa55 | 2018-04-10 00:10:49 +0000 | [diff] [blame] | 1401 | The remote port may either be forwarded to a specified host and port |
markus@openbsd.org | 609d7a6 | 2017-09-21 19:16:53 +0000 | [diff] [blame] | 1402 | from the local machine, or may act as a SOCKS 4/5 proxy that allows a remote |
| 1403 | client to connect to arbitrary destinations from the local machine. |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1404 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1405 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1406 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1407 | .Sm on |
markus@openbsd.org | 609d7a6 | 2017-09-21 19:16:53 +0000 | [diff] [blame] | 1408 | If forwarding to a specific destination then the second argument must be |
| 1409 | .Ar host : Ns Ar hostport , |
| 1410 | otherwise if no destination argument is specified then the remote forwarding |
| 1411 | will be established as a SOCKS proxy. |
| 1412 | .Pp |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 1413 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1414 | Multiple forwardings may be specified, and additional |
| 1415 | forwardings can be given on the command line. |
Damien Miller | de7532e | 2008-11-03 19:24:45 +1100 | [diff] [blame] | 1416 | Privileged ports can be forwarded only when |
| 1417 | logging in as root on the remote machine. |
Damien Miller | e379e10 | 2009-02-14 16:34:39 +1100 | [diff] [blame] | 1418 | .Pp |
Damien Miller | 85c6d8a | 2009-02-14 16:34:21 +1100 | [diff] [blame] | 1419 | If the |
| 1420 | .Ar port |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1421 | argument is 0, |
Damien Miller | 85c6d8a | 2009-02-14 16:34:21 +1100 | [diff] [blame] | 1422 | the listen port will be dynamically allocated on the server and reported |
| 1423 | to the client at run time. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1424 | .Pp |
| 1425 | If the |
| 1426 | .Ar bind_address |
| 1427 | is not specified, the default is to only bind to loopback addresses. |
| 1428 | If the |
| 1429 | .Ar bind_address |
| 1430 | is |
| 1431 | .Ql * |
| 1432 | or an empty string, then the forwarding is requested to listen on all |
| 1433 | interfaces. |
| 1434 | Specifying a remote |
| 1435 | .Ar bind_address |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1436 | will only succeed if the server's |
| 1437 | .Cm GatewayPorts |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1438 | option is enabled (see |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1439 | .Xr sshd_config 5 ) . |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1440 | .It Cm RequestTTY |
| 1441 | Specifies whether to request a pseudo-tty for the session. |
| 1442 | The argument may be one of: |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1443 | .Cm no |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1444 | (never request a TTY), |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1445 | .Cm yes |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1446 | (always request a TTY when standard input is a TTY), |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1447 | .Cm force |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1448 | (always request a TTY) or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1449 | .Cm auto |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1450 | (request a TTY when opening a login session). |
| 1451 | This option mirrors the |
| 1452 | .Fl t |
| 1453 | and |
| 1454 | .Fl T |
| 1455 | flags for |
| 1456 | .Xr ssh 1 . |
djm@openbsd.org | 5e39a49 | 2014-12-04 02:24:32 +0000 | [diff] [blame] | 1457 | .It Cm RevokedHostKeys |
| 1458 | Specifies revoked host public keys. |
| 1459 | Keys listed in this file will be refused for host authentication. |
| 1460 | Note that if this file does not exist or is not readable, |
| 1461 | then host authentication will be refused for all hosts. |
| 1462 | Keys may be specified as a text file, listing one public key per line, or as |
| 1463 | an OpenSSH Key Revocation List (KRL) as generated by |
| 1464 | .Xr ssh-keygen 1 . |
| 1465 | For more information on KRLs, see the KEY REVOCATION LISTS section in |
| 1466 | .Xr ssh-keygen 1 . |
naddy@openbsd.org | aa4c640 | 2019-11-07 08:38:38 +0000 | [diff] [blame] | 1467 | .It Cm SecurityKeyProvider |
naddy@openbsd.org | 141df48 | 2019-12-21 20:22:34 +0000 | [diff] [blame] | 1468 | Specifies a path to a library that will be used when loading any |
| 1469 | FIDO authenticator-hosted keys, overriding the default of using |
| 1470 | the built-in USB HID support. |
naddy@openbsd.org | 2cf262c | 2019-11-18 23:17:48 +0000 | [diff] [blame] | 1471 | .Pp |
| 1472 | If the specified value begins with a |
| 1473 | .Sq $ |
| 1474 | character, then it will be treated as an environment variable containing |
| 1475 | the path to the library. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1476 | .It Cm SendEnv |
| 1477 | Specifies what variables from the local |
| 1478 | .Xr environ 7 |
| 1479 | should be sent to the server. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1480 | 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] | 1481 | accept these environment variables. |
dtucker@openbsd.org | 85b96ef | 2015-04-28 10:17:58 +0000 | [diff] [blame] | 1482 | Note that the |
| 1483 | .Ev TERM |
jmc@openbsd.org | c1d5bcf | 2015-04-28 13:47:38 +0000 | [diff] [blame] | 1484 | environment variable is always sent whenever a |
dtucker@openbsd.org | 85b96ef | 2015-04-28 10:17:58 +0000 | [diff] [blame] | 1485 | pseudo-terminal is requested as it is required by the protocol. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1486 | Refer to |
| 1487 | .Cm AcceptEnv |
| 1488 | in |
| 1489 | .Xr sshd_config 5 |
| 1490 | for how to configure the server. |
Damien Miller | 6def551 | 2006-03-15 11:54:05 +1100 | [diff] [blame] | 1491 | Variables are specified by name, which may contain wildcard characters. |
Darren Tucker | 1e0c9bf | 2004-05-02 22:12:48 +1000 | [diff] [blame] | 1492 | Multiple environment variables may be separated by whitespace or spread |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1493 | across multiple |
| 1494 | .Cm SendEnv |
| 1495 | directives. |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 1496 | .Pp |
| 1497 | See |
| 1498 | .Sx PATTERNS |
| 1499 | for more information on patterns. |
djm@openbsd.org | 555294a | 2018-04-06 13:02:39 +0000 | [diff] [blame] | 1500 | .Pp |
jmc@openbsd.org | 8368571 | 2018-04-07 13:50:10 +0000 | [diff] [blame] | 1501 | It is possible to clear previously set |
djm@openbsd.org | 555294a | 2018-04-06 13:02:39 +0000 | [diff] [blame] | 1502 | .Cm SendEnv |
| 1503 | variable names by prefixing patterns with |
| 1504 | .Pa - . |
| 1505 | The default is not to send any environment variables. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1506 | .It Cm ServerAliveCountMax |
Damien Miller | b797770 | 2006-01-03 18:47:31 +1100 | [diff] [blame] | 1507 | Sets the number of server alive messages (see below) which may be |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1508 | sent without |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1509 | .Xr ssh 1 |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1510 | receiving any messages back from the server. |
| 1511 | If this threshold is reached while server alive messages are being sent, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1512 | ssh will disconnect from the server, terminating the session. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1513 | It is important to note that the use of server alive messages is very |
| 1514 | different from |
| 1515 | .Cm TCPKeepAlive |
| 1516 | (below). |
| 1517 | The server alive messages are sent through the encrypted channel |
| 1518 | and therefore will not be spoofable. |
| 1519 | The TCP keepalive option enabled by |
| 1520 | .Cm TCPKeepAlive |
| 1521 | is spoofable. |
| 1522 | The server alive mechanism is valuable when the client or |
dtucker@openbsd.org | 8fdbc72 | 2019-08-09 04:24:03 +0000 | [diff] [blame] | 1523 | server depend on knowing when a connection has become unresponsive. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1524 | .Pp |
| 1525 | The default value is 3. |
| 1526 | If, for example, |
| 1527 | .Cm ServerAliveInterval |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1528 | (see below) is set to 15 and |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1529 | .Cm ServerAliveCountMax |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1530 | is left at the default, if the server becomes unresponsive, |
| 1531 | ssh will disconnect after approximately 45 seconds. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1532 | .It Cm ServerAliveInterval |
| 1533 | Sets a timeout interval in seconds after which if no data has been received |
| 1534 | from the server, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1535 | .Xr ssh 1 |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1536 | will send a message through the encrypted |
| 1537 | channel to request a response from the server. |
| 1538 | The default |
| 1539 | is 0, indicating that these messages will not be sent to the server. |
jmc@openbsd.org | acf4260 | 2018-06-09 06:36:31 +0000 | [diff] [blame] | 1540 | .It Cm SetEnv |
| 1541 | Directly specify one or more environment variables and their contents to |
| 1542 | be sent to the server. |
| 1543 | Similarly to |
| 1544 | .Cm SendEnv , |
| 1545 | the server must be prepared to accept the environment variable. |
Damien Miller | 7acefbb | 2014-07-18 14:11:24 +1000 | [diff] [blame] | 1546 | .It Cm StreamLocalBindMask |
| 1547 | Sets the octal file creation mode mask |
| 1548 | .Pq umask |
| 1549 | used when creating a Unix-domain socket file for local or remote |
| 1550 | port forwarding. |
| 1551 | This option is only used for port forwarding to a Unix-domain socket file. |
| 1552 | .Pp |
| 1553 | The default value is 0177, which creates a Unix-domain socket file that is |
| 1554 | readable and writable only by the owner. |
| 1555 | Note that not all operating systems honor the file mode on Unix-domain |
| 1556 | socket files. |
| 1557 | .It Cm StreamLocalBindUnlink |
| 1558 | Specifies whether to remove an existing Unix-domain socket file for local |
| 1559 | or remote port forwarding before creating a new one. |
| 1560 | If the socket file already exists and |
| 1561 | .Cm StreamLocalBindUnlink |
| 1562 | is not enabled, |
| 1563 | .Nm ssh |
| 1564 | will be unable to forward the port to the Unix-domain socket file. |
| 1565 | This option is only used for port forwarding to a Unix-domain socket file. |
| 1566 | .Pp |
| 1567 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1568 | .Cm yes |
Damien Miller | 7acefbb | 2014-07-18 14:11:24 +1000 | [diff] [blame] | 1569 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1570 | .Cm no |
| 1571 | (the default). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1572 | .It Cm StrictHostKeyChecking |
| 1573 | If this flag is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1574 | .Cm yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1575 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1576 | will never automatically add host keys to the |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1577 | .Pa ~/.ssh/known_hosts |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1578 | file, and refuses to connect to hosts whose host key has changed. |
dtucker@openbsd.org | 3e61509 | 2018-02-06 06:01:54 +0000 | [diff] [blame] | 1579 | This provides maximum protection against man-in-the-middle (MITM) attacks, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1580 | though it can be annoying when the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1581 | .Pa /etc/ssh/ssh_known_hosts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1582 | file is poorly maintained or when connections to new hosts are |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1583 | frequently made. |
| 1584 | This option forces the user to manually |
| 1585 | add all new hosts. |
jmc@openbsd.org | 149a8cd | 2017-09-04 06:34:43 +0000 | [diff] [blame] | 1586 | .Pp |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1587 | If this flag is set to |
djm@openbsd.org | 22376d2 | 2017-09-03 23:33:13 +0000 | [diff] [blame] | 1588 | .Dq accept-new |
jmc@openbsd.org | 149a8cd | 2017-09-04 06:34:43 +0000 | [diff] [blame] | 1589 | then ssh will automatically add new host keys to the user |
djm@openbsd.org | 22376d2 | 2017-09-03 23:33:13 +0000 | [diff] [blame] | 1590 | known hosts files, but will not permit connections to hosts with |
| 1591 | changed host keys. |
| 1592 | If this flag is set to |
| 1593 | .Dq no |
| 1594 | or |
| 1595 | .Dq off , |
jmc@openbsd.org | 149a8cd | 2017-09-04 06:34:43 +0000 | [diff] [blame] | 1596 | ssh will automatically add new host keys to the user known hosts files |
| 1597 | and allow connections to hosts with changed hostkeys to proceed, |
| 1598 | subject to some restrictions. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1599 | If this flag is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1600 | .Cm ask |
| 1601 | (the default), |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1602 | new host keys |
| 1603 | will be added to the user known host files only after the user |
| 1604 | has confirmed that is what they really want to do, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1605 | ssh will refuse to connect to hosts whose host key has changed. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1606 | The host keys of |
| 1607 | known hosts will be verified automatically in all cases. |
jmc@openbsd.org | 47a287b | 2017-04-28 06:15:03 +0000 | [diff] [blame] | 1608 | .It Cm SyslogFacility |
| 1609 | Gives the facility code that is used when logging messages from |
| 1610 | .Xr ssh 1 . |
| 1611 | The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, |
| 1612 | LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. |
| 1613 | The default is USER. |
Damien Miller | 12c150e | 2003-12-17 16:31:10 +1100 | [diff] [blame] | 1614 | .It Cm TCPKeepAlive |
| 1615 | Specifies whether the system should send TCP keepalive messages to the |
| 1616 | other side. |
| 1617 | If they are sent, death of the connection or crash of one |
| 1618 | of the machines will be properly noticed. |
| 1619 | However, this means that |
| 1620 | connections will die if the route is down temporarily, and some people |
| 1621 | find it annoying. |
| 1622 | .Pp |
| 1623 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1624 | .Cm yes |
Damien Miller | 12c150e | 2003-12-17 16:31:10 +1100 | [diff] [blame] | 1625 | (to send TCP keepalive messages), and the client will notice |
| 1626 | if the network goes down or the remote host dies. |
| 1627 | This is important in scripts, and many users want it too. |
| 1628 | .Pp |
| 1629 | To disable TCP keepalive messages, the value should be set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1630 | .Cm no . |
djm@openbsd.org | a7c3821 | 2018-02-10 09:03:54 +0000 | [diff] [blame] | 1631 | See also |
| 1632 | .Cm ServerAliveInterval |
| 1633 | for protocol-level keepalives. |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1634 | .It Cm Tunnel |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1635 | Request |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1636 | .Xr tun 4 |
Damien Miller | 7746c39 | 2005-12-13 19:33:37 +1100 | [diff] [blame] | 1637 | device forwarding between the client and the server. |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1638 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1639 | .Cm yes , |
| 1640 | .Cm point-to-point |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1641 | (layer 3), |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1642 | .Cm ethernet |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1643 | (layer 2), |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1644 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1645 | .Cm no |
| 1646 | (the default). |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1647 | Specifying |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1648 | .Cm yes |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1649 | requests the default tunnel mode, which is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1650 | .Cm point-to-point . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1651 | .It Cm TunnelDevice |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1652 | Specifies the |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1653 | .Xr tun 4 |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1654 | devices to open on the client |
| 1655 | .Pq Ar local_tun |
| 1656 | and the server |
| 1657 | .Pq Ar remote_tun . |
| 1658 | .Pp |
| 1659 | The argument must be |
| 1660 | .Sm off |
| 1661 | .Ar local_tun Op : Ar remote_tun . |
| 1662 | .Sm on |
| 1663 | The devices may be specified by numerical ID or the keyword |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1664 | .Cm any , |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1665 | which uses the next available tunnel device. |
| 1666 | If |
| 1667 | .Ar remote_tun |
| 1668 | is not specified, it defaults to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1669 | .Cm any . |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1670 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1671 | .Cm any:any . |
djm@openbsd.org | 1d1092b | 2015-01-26 12:16:36 +0000 | [diff] [blame] | 1672 | .It Cm UpdateHostKeys |
djm@openbsd.org | 8d4f872 | 2015-01-26 03:04:45 +0000 | [diff] [blame] | 1673 | Specifies whether |
| 1674 | .Xr ssh 1 |
| 1675 | should accept notifications of additional hostkeys from the server sent |
| 1676 | after authentication has completed and add them to |
| 1677 | .Cm UserKnownHostsFile . |
| 1678 | The argument must be |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1679 | .Cm yes , |
| 1680 | .Cm no |
djm@openbsd.org | 771891a | 2020-01-30 22:25:34 +0000 | [diff] [blame] | 1681 | or |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1682 | .Cm ask . |
djm@openbsd.org | 771891a | 2020-01-30 22:25:34 +0000 | [diff] [blame] | 1683 | This option allows learning alternate hostkeys for a server |
djm@openbsd.org | 1d1092b | 2015-01-26 12:16:36 +0000 | [diff] [blame] | 1684 | and supports graceful key rotation by allowing a server to send replacement |
| 1685 | public keys before old ones are removed. |
djm@openbsd.org | 8d4f872 | 2015-01-26 03:04:45 +0000 | [diff] [blame] | 1686 | Additional hostkeys are only accepted if the key used to authenticate the |
sobrado@openbsd.org | e3cbb06 | 2015-09-22 08:33:23 +0000 | [diff] [blame] | 1687 | host was already trusted or explicitly accepted by the user. |
djm@openbsd.org | 771891a | 2020-01-30 22:25:34 +0000 | [diff] [blame] | 1688 | .Pp |
| 1689 | .Cm UpdateHostKeys |
jmc@openbsd.org | ba261a1 | 2020-01-31 22:25:59 +0000 | [diff] [blame] | 1690 | is enabled by default if the user has not overridden the default |
djm@openbsd.org | 771891a | 2020-01-30 22:25:34 +0000 | [diff] [blame] | 1691 | .Cm UserKnownHostsFile |
| 1692 | setting, otherwise |
| 1693 | .Cm UpdateHostKeys |
| 1694 | will be set to |
| 1695 | .Cm ask . |
| 1696 | .Pp |
djm@openbsd.org | 523463a | 2015-02-16 22:13:32 +0000 | [diff] [blame] | 1697 | If |
| 1698 | .Cm UpdateHostKeys |
| 1699 | is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1700 | .Cm ask , |
djm@openbsd.org | 523463a | 2015-02-16 22:13:32 +0000 | [diff] [blame] | 1701 | then the user is asked to confirm the modifications to the known_hosts file. |
djm@openbsd.org | 44732de | 2015-02-20 22:17:21 +0000 | [diff] [blame] | 1702 | Confirmation is currently incompatible with |
| 1703 | .Cm ControlPersist , |
| 1704 | and will be disabled if it is enabled. |
djm@openbsd.org | 8d4f872 | 2015-01-26 03:04:45 +0000 | [diff] [blame] | 1705 | .Pp |
| 1706 | Presently, only |
| 1707 | .Xr sshd 8 |
| 1708 | from OpenSSH 6.8 and greater support the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1709 | .Qq hostkeys@openssh.com |
djm@openbsd.org | 8d4f872 | 2015-01-26 03:04:45 +0000 | [diff] [blame] | 1710 | protocol extension used to inform the client of all the server's hostkeys. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1711 | .It Cm User |
| 1712 | Specifies the user to log in as. |
| 1713 | This can be useful when a different user name is used on different machines. |
| 1714 | This saves the trouble of |
| 1715 | having to remember to give the user name on the command line. |
| 1716 | .It Cm UserKnownHostsFile |
Damien Miller | 295ee63 | 2011-05-29 21:42:31 +1000 | [diff] [blame] | 1717 | Specifies one or more files to use for the user |
| 1718 | host key database, separated by whitespace. |
| 1719 | The default is |
| 1720 | .Pa ~/.ssh/known_hosts , |
| 1721 | .Pa ~/.ssh/known_hosts2 . |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1722 | .It Cm VerifyHostKeyDNS |
| 1723 | Specifies whether to verify the remote key using DNS and SSHFP resource |
| 1724 | records. |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1725 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1726 | .Cm yes , |
Damien Miller | fe44847 | 2003-11-17 21:19:49 +1100 | [diff] [blame] | 1727 | the client will implicitly trust keys that match a secure fingerprint |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1728 | from DNS. |
| 1729 | Insecure fingerprints will be handled as if this option was set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1730 | .Cm ask . |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1731 | If this option is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1732 | .Cm ask , |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1733 | information on fingerprint match will be displayed, but the user will still |
| 1734 | need to confirm new host keys according to the |
| 1735 | .Cm StrictHostKeyChecking |
| 1736 | option. |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1737 | The default is |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1738 | .Cm no . |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1739 | .Pp |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1740 | See also |
| 1741 | .Sx VERIFYING HOST KEYS |
| 1742 | in |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1743 | .Xr ssh 1 . |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1744 | .It Cm VisualHostKey |
| 1745 | If this flag is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1746 | .Cm yes , |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1747 | an ASCII art representation of the remote host key fingerprint is |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 1748 | printed in addition to the fingerprint string at login and |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1749 | for unknown host keys. |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1750 | If this flag is set to |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1751 | .Cm no |
| 1752 | (the default), |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1753 | no fingerprint strings are printed at login and |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 1754 | only the fingerprint string will be printed for unknown host keys. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1755 | .It Cm XAuthLocation |
Damien Miller | 05913ba | 2002-09-04 16:51:03 +1000 | [diff] [blame] | 1756 | Specifies the full pathname of the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1757 | .Xr xauth 1 |
| 1758 | program. |
| 1759 | The default is |
| 1760 | .Pa /usr/X11R6/bin/xauth . |
| 1761 | .El |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1762 | .Sh PATTERNS |
| 1763 | A |
| 1764 | .Em pattern |
| 1765 | consists of zero or more non-whitespace characters, |
| 1766 | .Sq * |
| 1767 | (a wildcard that matches zero or more characters), |
| 1768 | or |
| 1769 | .Sq ?\& |
| 1770 | (a wildcard that matches exactly one character). |
| 1771 | For example, to specify a set of declarations for any host in the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1772 | .Qq .co.uk |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1773 | set of domains, |
| 1774 | the following pattern could be used: |
| 1775 | .Pp |
| 1776 | .Dl Host *.co.uk |
| 1777 | .Pp |
| 1778 | The following pattern |
| 1779 | would match any host in the 192.168.0.[0-9] network range: |
| 1780 | .Pp |
| 1781 | .Dl Host 192.168.0.? |
| 1782 | .Pp |
| 1783 | A |
| 1784 | .Em pattern-list |
| 1785 | is a comma-separated list of patterns. |
| 1786 | Patterns within pattern-lists may be negated |
| 1787 | by preceding them with an exclamation mark |
| 1788 | .Pq Sq !\& . |
| 1789 | For example, |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 1790 | to allow a key to be used from anywhere within an organization |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1791 | except from the |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1792 | .Qq dialup |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1793 | pool, |
| 1794 | the following entry (in authorized_keys) could be used: |
| 1795 | .Pp |
| 1796 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" |
djm@openbsd.org | 05b69e9 | 2017-10-18 02:49:44 +0000 | [diff] [blame] | 1797 | .Pp |
| 1798 | Note that a negated match will never produce a positive result by itself. |
| 1799 | For example, attempting to match |
| 1800 | .Qq host3 |
| 1801 | against the following pattern-list will fail: |
| 1802 | .Pp |
| 1803 | .Dl from=\&"!host1,!host2\&" |
| 1804 | .Pp |
| 1805 | The solution here is to include a term that will yield a positive match, |
| 1806 | such as a wildcard: |
| 1807 | .Pp |
| 1808 | .Dl from=\&"!host1,!host2,*\&" |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1809 | .Sh TOKENS |
| 1810 | Arguments to some keywords can make use of tokens, |
| 1811 | which are expanded at runtime: |
| 1812 | .Pp |
| 1813 | .Bl -tag -width XXXX -offset indent -compact |
| 1814 | .It %% |
| 1815 | A literal |
| 1816 | .Sq % . |
| 1817 | .It \&%C |
jmc@openbsd.org | 2b4f3ab | 2017-10-05 12:56:50 +0000 | [diff] [blame] | 1818 | Hash of %l%h%p%r. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1819 | .It %d |
| 1820 | Local user's home directory. |
| 1821 | .It %h |
| 1822 | The remote hostname. |
| 1823 | .It %i |
| 1824 | The local user ID. |
| 1825 | .It %L |
| 1826 | The local hostname. |
| 1827 | .It %l |
| 1828 | The local hostname, including the domain name. |
| 1829 | .It %n |
| 1830 | The original remote hostname, as given on the command line. |
| 1831 | .It %p |
| 1832 | The remote port. |
| 1833 | .It %r |
| 1834 | The remote username. |
djm@openbsd.org | b7548b1 | 2017-10-23 05:08:00 +0000 | [diff] [blame] | 1835 | .It \&%T |
| 1836 | The local |
| 1837 | .Xr tun 4 |
| 1838 | or |
| 1839 | .Xr tap 4 |
| 1840 | network interface assigned if |
jmc@openbsd.org | 0869627 | 2017-10-24 06:27:42 +0000 | [diff] [blame] | 1841 | tunnel forwarding was requested, or |
| 1842 | .Qq NONE |
djm@openbsd.org | b7548b1 | 2017-10-23 05:08:00 +0000 | [diff] [blame] | 1843 | otherwise. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1844 | .It %u |
| 1845 | The local username. |
| 1846 | .El |
| 1847 | .Pp |
dtucker@openbsd.org | ed833da | 2020-04-03 02:27:12 +0000 | [diff] [blame^] | 1848 | .Cm Match exec , |
| 1849 | .Cm CertificateFile , |
| 1850 | .Cm ControlPath , |
| 1851 | .Cm IdentityAgent , |
| 1852 | .Cm IdentityFile , |
| 1853 | and |
| 1854 | .Cm RemoteCommand |
| 1855 | accept the tokens %%, %C, %d, %h, %i, %L, %l, %n, %p, %r, and %u. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1856 | .Pp |
jmc@openbsd.org | 76af9c5 | 2019-06-12 05:53:21 +0000 | [diff] [blame] | 1857 | .Cm Hostname |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1858 | accepts the tokens %% and %h. |
| 1859 | .Pp |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1860 | .Cm LocalCommand |
dtucker@openbsd.org | ed833da | 2020-04-03 02:27:12 +0000 | [diff] [blame^] | 1861 | accepts all tokens. |
jmc@openbsd.org | 80d1c96 | 2016-09-28 17:59:22 +0000 | [diff] [blame] | 1862 | .Pp |
| 1863 | .Cm ProxyCommand |
djm@openbsd.org | fbe24b1 | 2019-09-13 04:27:35 +0000 | [diff] [blame] | 1864 | accepts the tokens %%, %h, %n, %p, and %r. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1865 | .Sh FILES |
| 1866 | .Bl -tag -width Ds |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1867 | .It Pa ~/.ssh/config |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1868 | This is the per-user configuration file. |
| 1869 | The format of this file is described above. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1870 | This file is used by the SSH client. |
Damien Miller | c970cb9 | 2004-04-20 20:12:53 +1000 | [diff] [blame] | 1871 | Because of the potential for abuse, this file must have strict permissions: |
jmc@openbsd.org | d9ecfab | 2019-02-18 07:02:34 +0000 | [diff] [blame] | 1872 | read/write for the user, and not writable by others. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1873 | .It Pa /etc/ssh/ssh_config |
| 1874 | Systemwide configuration file. |
| 1875 | This file provides defaults for those |
| 1876 | values that are not specified in the user's configuration file, and |
| 1877 | for those users who do not have a configuration file. |
| 1878 | This file must be world-readable. |
| 1879 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 1880 | .Sh SEE ALSO |
| 1881 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1882 | .Sh AUTHORS |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1883 | .An -nosplit |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1884 | OpenSSH is a derivative of the original and free |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1885 | ssh 1.2.12 release by |
| 1886 | .An Tatu Ylonen . |
| 1887 | .An Aaron Campbell , Bob Beck , Markus Friedl , |
| 1888 | .An Niels Provos , Theo de Raadt |
| 1889 | and |
| 1890 | .An Dug Song |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1891 | removed many bugs, re-added newer features and |
| 1892 | created OpenSSH. |
jmc@openbsd.org | fd2a8f1 | 2016-10-15 19:56:25 +0000 | [diff] [blame] | 1893 | .An Markus Friedl |
| 1894 | contributed the support for SSH protocol versions 1.5 and 2.0. |