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 | .\" |
jmc@openbsd.org | 296ef05 | 2014-12-22 09:24:59 +0000 | [diff] [blame] | 36 | .\" $OpenBSD: ssh_config.5,v 1.199 2014/12/22 09:24:59 jmc Exp $ |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 37 | .Dd $Mdocdate: December 22 2014 $ |
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 |
| 42 | .Nd OpenSSH SSH client configuration files |
| 43 | .Sh SYNOPSIS |
Darren Tucker | bf6b328 | 2007-02-19 22:08:17 +1100 | [diff] [blame] | 44 | .Nm ~/.ssh/config |
| 45 | .Nm /etc/ssh/ssh_config |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 46 | .Sh DESCRIPTION |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 47 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 48 | obtains configuration data from the following sources in |
| 49 | the following order: |
Damien Miller | 5c853b5 | 2006-03-15 11:37:02 +1100 | [diff] [blame] | 50 | .Pp |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 51 | .Bl -enum -offset indent -compact |
| 52 | .It |
| 53 | command-line options |
| 54 | .It |
| 55 | user's configuration file |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 56 | .Pq Pa ~/.ssh/config |
Ben Lindstrom | 479b476 | 2002-08-20 19:04:51 +0000 | [diff] [blame] | 57 | .It |
| 58 | system-wide configuration file |
| 59 | .Pq Pa /etc/ssh/ssh_config |
| 60 | .El |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 61 | .Pp |
| 62 | For each parameter, the first obtained value |
| 63 | will be used. |
Darren Tucker | 43d8e28 | 2005-02-09 09:51:08 +1100 | [diff] [blame] | 64 | The configuration files contain sections separated by |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 65 | .Dq Host |
| 66 | specifications, and that section is only applied for hosts that |
| 67 | match one of the patterns given in the specification. |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 68 | The matched host name is usually the one given on the command line |
| 69 | (see the |
| 70 | .Cm CanonicalizeHostname |
| 71 | option for exceptions.) |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 72 | .Pp |
| 73 | Since the first obtained value for each parameter is used, more |
| 74 | host-specific declarations should be given near the beginning of the |
| 75 | file, and general defaults at the end. |
| 76 | .Pp |
| 77 | The configuration file has the following format: |
| 78 | .Pp |
| 79 | Empty lines and lines starting with |
| 80 | .Ql # |
| 81 | are comments. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 82 | Otherwise a line is of the format |
| 83 | .Dq keyword arguments . |
| 84 | Configuration options may be separated by whitespace or |
| 85 | optional whitespace and exactly one |
| 86 | .Ql = ; |
| 87 | the latter format is useful to avoid the need to quote whitespace |
| 88 | when specifying configuration options using the |
| 89 | .Nm ssh , |
Damien Miller | 4aea974 | 2006-03-15 11:59:39 +1100 | [diff] [blame] | 90 | .Nm scp , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 91 | and |
| 92 | .Nm sftp |
| 93 | .Fl o |
| 94 | option. |
Damien Miller | 306d118 | 2006-03-15 12:05:59 +1100 | [diff] [blame] | 95 | Arguments may optionally be enclosed in double quotes |
| 96 | .Pq \&" |
| 97 | in order to represent arguments containing spaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 98 | .Pp |
| 99 | The possible |
| 100 | keywords and their meanings are as follows (note that |
| 101 | keywords are case-insensitive and arguments are case-sensitive): |
| 102 | .Bl -tag -width Ds |
| 103 | .It Cm Host |
| 104 | Restricts the following declarations (up to the next |
| 105 | .Cm Host |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 106 | or |
| 107 | .Cm Match |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 108 | keyword) to be only for those hosts that match one of the patterns |
| 109 | given after the keyword. |
Damien Miller | fa51b16 | 2008-11-03 19:17:33 +1100 | [diff] [blame] | 110 | 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] | 111 | A single |
Damien Miller | 208f1ed | 2006-03-15 11:56:03 +1100 | [diff] [blame] | 112 | .Ql * |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 113 | as a pattern can be used to provide global |
| 114 | defaults for all hosts. |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 115 | The host is usually the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 116 | .Ar hostname |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 117 | argument given on the command line |
| 118 | (see the |
| 119 | .Cm CanonicalizeHostname |
| 120 | option for exceptions.) |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 121 | .Pp |
Damien Miller | fe92421 | 2011-05-15 08:44:45 +1000 | [diff] [blame] | 122 | A pattern entry may be negated by prefixing it with an exclamation mark |
| 123 | .Pq Sq !\& . |
| 124 | If a negated entry is matched, then the |
| 125 | .Cm Host |
| 126 | entry is ignored, regardless of whether any other patterns on the line |
| 127 | match. |
| 128 | Negated matches are therefore useful to provide exceptions for wildcard |
| 129 | matches. |
| 130 | .Pp |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 131 | See |
| 132 | .Sx PATTERNS |
| 133 | for more information on patterns. |
Damien Miller | d77b81f | 2013-10-17 11:39:00 +1100 | [diff] [blame] | 134 | .It Cm Match |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 135 | Restricts the following declarations (up to the next |
| 136 | .Cm Host |
| 137 | or |
| 138 | .Cm Match |
| 139 | keyword) to be used only when the conditions following the |
| 140 | .Cm Match |
| 141 | keyword are satisfied. |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 142 | Match conditions are specified using one or more critera |
Damien Miller | cf31f38 | 2013-10-24 21:02:56 +1100 | [diff] [blame] | 143 | or the single token |
| 144 | .Cm all |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 145 | which always matches. |
| 146 | The available criteria keywords are: |
| 147 | .Cm canonical , |
Damien Miller | 8a04be7 | 2013-10-23 16:29:40 +1100 | [diff] [blame] | 148 | .Cm exec , |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 149 | .Cm host , |
| 150 | .Cm originalhost , |
| 151 | .Cm user , |
| 152 | and |
| 153 | .Cm localuser . |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 154 | The |
| 155 | .Cm all |
| 156 | criteria must appear alone or immediately after |
jmc@openbsd.org | b1ba15f | 2014-10-09 06:21:31 +0000 | [diff] [blame] | 157 | .Cm canonical . |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 158 | Other criteria may be combined arbitrarily. |
| 159 | All criteria but |
| 160 | .Cm all |
| 161 | and |
| 162 | .Cm canonical |
| 163 | require an argument. |
| 164 | Criteria may be negated by prepending an exclamation mark |
| 165 | .Pq Sq !\& . |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 166 | .Pp |
Damien Miller | 8e5a67f | 2013-10-23 16:30:25 +1100 | [diff] [blame] | 167 | The |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 168 | .Cm canonical |
| 169 | keywork matches only when the configuration file is being re-parsed |
| 170 | after hostname canonicalization (see the |
| 171 | .Cm CanonicalizeHostname |
| 172 | option.) |
| 173 | This may be useful to specify conditions that work with canonical host |
| 174 | names only. |
| 175 | The |
Damien Miller | 8a04be7 | 2013-10-23 16:29:40 +1100 | [diff] [blame] | 176 | .Cm exec |
Damien Miller | 8e5a67f | 2013-10-23 16:30:25 +1100 | [diff] [blame] | 177 | keyword executes the specified command under the user's shell. |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 178 | If the command returns a zero exit status then the condition is considered true. |
| 179 | Commands containing whitespace characters must be quoted. |
Damien Miller | 5c86ebd | 2013-10-23 16:29:12 +1100 | [diff] [blame] | 180 | The following character sequences in the command will be expanded prior to |
| 181 | execution: |
| 182 | .Ql %L |
| 183 | will be substituted by the first component of the local host name, |
| 184 | .Ql %l |
| 185 | will be substituted by the local host name (including any domain name), |
| 186 | .Ql %h |
| 187 | will be substituted by the target host name, |
| 188 | .Ql %n |
| 189 | will be substituted by the original target host name |
Damien Miller | 8a04be7 | 2013-10-23 16:29:40 +1100 | [diff] [blame] | 190 | specified on the command-line, |
Damien Miller | 5c86ebd | 2013-10-23 16:29:12 +1100 | [diff] [blame] | 191 | .Ql %p |
| 192 | the destination port, |
| 193 | .Ql %r |
| 194 | by the remote login username, and |
| 195 | .Ql %u |
| 196 | by the username of the user running |
| 197 | .Xr ssh 1 . |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 198 | .Pp |
| 199 | The other keywords' criteria must be single entries or comma-separated |
| 200 | lists and may use the wildcard and negation operators described in the |
| 201 | .Sx PATTERNS |
| 202 | section. |
| 203 | The criteria for the |
| 204 | .Cm host |
| 205 | keyword are matched against the target hostname, after any substitution |
| 206 | by the |
| 207 | .Cm Hostname |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 208 | or |
| 209 | .Cm CanonicalizeHostname |
| 210 | options. |
Damien Miller | 194fd90 | 2013-10-15 12:13:05 +1100 | [diff] [blame] | 211 | The |
| 212 | .Cm originalhost |
| 213 | keyword matches against the hostname as it was specified on the command-line. |
| 214 | The |
| 215 | .Cm user |
| 216 | keyword matches against the target username on the remote host. |
| 217 | The |
| 218 | .Cm localuser |
| 219 | keyword matches against the name of the local user running |
| 220 | .Xr ssh 1 |
| 221 | (this keyword may be useful in system-wide |
| 222 | .Nm |
| 223 | files). |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 224 | .It Cm AddressFamily |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 225 | Specifies which address family to use when connecting. |
| 226 | Valid arguments are |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 227 | .Dq any , |
| 228 | .Dq inet |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 229 | (use IPv4 only), or |
Damien Miller | 20a8f97 | 2003-05-18 20:50:30 +1000 | [diff] [blame] | 230 | .Dq inet6 |
Darren Tucker | 79a7acf | 2005-02-09 09:48:57 +1100 | [diff] [blame] | 231 | (use IPv6 only). |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 232 | .It Cm BatchMode |
| 233 | If set to |
| 234 | .Dq yes , |
| 235 | passphrase/password querying will be disabled. |
| 236 | This option is useful in scripts and other batch jobs where no user |
| 237 | is present to supply the password. |
| 238 | The argument must be |
| 239 | .Dq yes |
| 240 | or |
| 241 | .Dq no . |
| 242 | The default is |
| 243 | .Dq no . |
| 244 | .It Cm BindAddress |
Darren Tucker | 89f4d47 | 2005-07-14 17:06:21 +1000 | [diff] [blame] | 245 | 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] | 246 | the connection. |
| 247 | Only useful on systems with more than one address. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 248 | Note that this option does not work if |
| 249 | .Cm UsePrivilegedPort |
| 250 | is set to |
| 251 | .Dq yes . |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 252 | .It Cm CanonicalDomains |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 253 | When |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 254 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 255 | is enabled, this option specifies the list of domain suffixes in which to |
| 256 | search for the specified destination host. |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 257 | .It Cm CanonicalizeFallbackLocal |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 258 | Specifies whether to fail with an error when hostname canonicalization fails. |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 259 | The default, |
Darren Tucker | b7e01c0 | 2014-01-19 22:36:13 +1100 | [diff] [blame] | 260 | .Dq yes , |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 261 | 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] | 262 | search rules. |
| 263 | A value of |
Darren Tucker | b7e01c0 | 2014-01-19 22:36:13 +1100 | [diff] [blame] | 264 | .Dq no |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 265 | will cause |
| 266 | .Xr ssh 1 |
| 267 | to fail instantly if |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 268 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 269 | is enabled and the target hostname cannot be found in any of the domains |
| 270 | specified by |
| 271 | .Cm CanonicalDomains . |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 272 | .It Cm CanonicalizeHostname |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 273 | Controls whether explicit hostname canonicalization is performed. |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 274 | The default, |
| 275 | .Dq no , |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 276 | is not to perform any name rewriting and let the system resolver handle all |
| 277 | hostname lookups. |
| 278 | If set to |
| 279 | .Dq yes |
| 280 | then, for connections that do not use a |
| 281 | .Cm ProxyCommand , |
| 282 | .Xr ssh 1 |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 283 | will attempt to canonicalize the hostname specified on the command line |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 284 | using the |
| 285 | .Cm CanonicalDomains |
| 286 | suffixes and |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 287 | .Cm CanonicalizePermittedCNAMEs |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 288 | rules. |
| 289 | If |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 290 | .Cm CanonicalizeHostname |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 291 | is set to |
| 292 | .Dq always , |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 293 | then canonicalization is applied to proxied connections too. |
Damien Miller | 13f97b2 | 2014-02-24 15:57:55 +1100 | [diff] [blame] | 294 | .Pp |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 295 | If this option is enabled, then the configuration files are processed |
| 296 | 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] | 297 | .Cm Host |
djm@openbsd.org | 957fbce | 2014-10-08 22:20:25 +0000 | [diff] [blame] | 298 | and |
| 299 | .Cm Match |
Damien Miller | 13f97b2 | 2014-02-24 15:57:55 +1100 | [diff] [blame] | 300 | stanzas. |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 301 | .It Cm CanonicalizeMaxDots |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 302 | Specifies the maximum number of dot characters in a hostname before |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 303 | canonicalization is disabled. |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 304 | The default, |
| 305 | .Dq 1 , |
| 306 | allows a single dot (i.e. hostname.subdomain). |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 307 | .It Cm CanonicalizePermittedCNAMEs |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 308 | Specifies rules to determine whether CNAMEs should be followed when |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 309 | canonicalizing hostnames. |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 310 | The rules consist of one or more arguments of |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 311 | .Ar source_domain_list : Ns Ar target_domain_list , |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 312 | where |
| 313 | .Ar source_domain_list |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 314 | is a pattern-list of domains that may follow CNAMEs in canonicalization, |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 315 | and |
| 316 | .Ar target_domain_list |
Damien Miller | 607af34 | 2013-10-17 11:47:51 +1100 | [diff] [blame] | 317 | is a pattern-list of domains that they may resolve to. |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 318 | .Pp |
| 319 | For example, |
| 320 | .Dq *.a.example.com:*.b.example.com,*.c.example.com |
| 321 | will allow hostnames matching |
| 322 | .Dq *.a.example.com |
Damien Miller | 3850559 | 2013-10-17 11:48:13 +1100 | [diff] [blame] | 323 | to be canonicalized to names in the |
Damien Miller | 0faf747 | 2013-10-17 11:47:23 +1100 | [diff] [blame] | 324 | .Dq *.b.example.com |
| 325 | or |
| 326 | .Dq *.c.example.com |
| 327 | domains. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 328 | .It Cm ChallengeResponseAuthentication |
Damien Miller | 1faa713 | 2006-03-15 11:55:31 +1100 | [diff] [blame] | 329 | Specifies whether to use challenge-response authentication. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 330 | The argument to this keyword must be |
| 331 | .Dq yes |
| 332 | or |
| 333 | .Dq no . |
| 334 | The default is |
| 335 | .Dq yes . |
| 336 | .It Cm CheckHostIP |
| 337 | If this flag is set to |
| 338 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 339 | .Xr ssh 1 |
| 340 | will additionally check the host IP address in the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 341 | .Pa known_hosts |
| 342 | file. |
| 343 | This allows ssh to detect if a host key changed due to DNS spoofing. |
| 344 | If the option is set to |
| 345 | .Dq no , |
| 346 | the check will not be executed. |
| 347 | The default is |
| 348 | .Dq yes . |
| 349 | .It Cm Cipher |
| 350 | Specifies the cipher to use for encrypting the session |
| 351 | in protocol version 1. |
| 352 | Currently, |
| 353 | .Dq blowfish , |
| 354 | .Dq 3des , |
| 355 | and |
| 356 | .Dq des |
| 357 | are supported. |
| 358 | .Ar des |
| 359 | is only supported in the |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 360 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 361 | client for interoperability with legacy protocol 1 implementations |
| 362 | that do not support the |
| 363 | .Ar 3des |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 364 | cipher. |
| 365 | Its use is strongly discouraged due to cryptographic weaknesses. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 366 | The default is |
| 367 | .Dq 3des . |
| 368 | .It Cm Ciphers |
| 369 | Specifies the ciphers allowed for protocol version 2 |
| 370 | in order of preference. |
| 371 | Multiple ciphers must be comma-separated. |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 372 | The supported ciphers are: |
| 373 | .Pp |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 374 | .Bl -item -compact -offset indent |
| 375 | .It |
| 376 | 3des-cbc |
| 377 | .It |
| 378 | aes128-cbc |
| 379 | .It |
| 380 | aes192-cbc |
| 381 | .It |
| 382 | aes256-cbc |
| 383 | .It |
| 384 | aes128-ctr |
| 385 | .It |
| 386 | aes192-ctr |
| 387 | .It |
| 388 | aes256-ctr |
| 389 | .It |
| 390 | aes128-gcm@openssh.com |
| 391 | .It |
| 392 | aes256-gcm@openssh.com |
| 393 | .It |
| 394 | arcfour |
| 395 | .It |
| 396 | arcfour128 |
| 397 | .It |
| 398 | arcfour256 |
| 399 | .It |
| 400 | blowfish-cbc |
| 401 | .It |
| 402 | cast128-cbc |
| 403 | .It |
| 404 | chacha20-poly1305@openssh.com |
| 405 | .El |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 406 | .Pp |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 407 | The default is: |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 408 | .Bd -literal -offset indent |
| 409 | aes128-ctr,aes192-ctr,aes256-ctr, |
Damien Miller | 1d75abf | 2013-01-09 16:12:19 +1100 | [diff] [blame] | 410 | aes128-gcm@openssh.com,aes256-gcm@openssh.com, |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 411 | chacha20-poly1305@openssh.com, |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 412 | arcfour256,arcfour128, |
| 413 | aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc, |
| 414 | aes192-cbc,aes256-cbc,arcfour |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 415 | .Ed |
Damien Miller | 0fde8ac | 2013-11-21 14:12:23 +1100 | [diff] [blame] | 416 | .Pp |
| 417 | The list of available ciphers may also be obtained using the |
| 418 | .Fl Q |
| 419 | option of |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 420 | .Xr ssh 1 |
| 421 | with an argument of |
| 422 | .Dq cipher . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 423 | .It Cm ClearAllForwardings |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 424 | Specifies that all local, remote, and dynamic port forwardings |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 425 | specified in the configuration files or on the command line be |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 426 | cleared. |
| 427 | This option is primarily useful when used from the |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 428 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 429 | command line to clear port forwardings set in |
| 430 | configuration files, and is automatically set by |
| 431 | .Xr scp 1 |
| 432 | and |
| 433 | .Xr sftp 1 . |
| 434 | The argument must be |
| 435 | .Dq yes |
| 436 | or |
| 437 | .Dq no . |
| 438 | The default is |
| 439 | .Dq no . |
| 440 | .It Cm Compression |
| 441 | Specifies whether to use compression. |
| 442 | The argument must be |
| 443 | .Dq yes |
| 444 | or |
| 445 | .Dq no . |
| 446 | The default is |
| 447 | .Dq no . |
| 448 | .It Cm CompressionLevel |
| 449 | Specifies the compression level to use if compression is enabled. |
| 450 | The argument must be an integer from 1 (fast) to 9 (slow, best). |
| 451 | The default level is 6, which is good for most applications. |
| 452 | The meaning of the values is the same as in |
| 453 | .Xr gzip 1 . |
| 454 | Note that this option applies to protocol version 1 only. |
| 455 | .It Cm ConnectionAttempts |
| 456 | Specifies the number of tries (one per second) to make before exiting. |
| 457 | The argument must be an integer. |
| 458 | This may be useful in scripts if the connection sometimes fails. |
| 459 | The default is 1. |
Damien Miller | b78d5eb | 2003-05-16 11:39:04 +1000 | [diff] [blame] | 460 | .It Cm ConnectTimeout |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 461 | Specifies the timeout (in seconds) used when connecting to the |
| 462 | SSH server, instead of using the default system TCP timeout. |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 463 | This value is used only when the target is down or really unreachable, |
| 464 | not when it refuses the connection. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 465 | .It Cm ControlMaster |
| 466 | Enables the sharing of multiple sessions over a single network connection. |
| 467 | When set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 468 | .Dq yes , |
| 469 | .Xr ssh 1 |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 470 | will listen for connections on a control socket specified using the |
| 471 | .Cm ControlPath |
| 472 | argument. |
| 473 | Additional sessions can connect to this socket using the same |
| 474 | .Cm ControlPath |
| 475 | with |
| 476 | .Cm ControlMaster |
| 477 | set to |
| 478 | .Dq no |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 479 | (the default). |
Damien Miller | 713de76 | 2005-11-05 15:13:49 +1100 | [diff] [blame] | 480 | These sessions will try to reuse the master instance's network connection |
Damien Miller | b3bfbb7 | 2005-11-05 15:11:48 +1100 | [diff] [blame] | 481 | rather than initiating new ones, but will fall back to connecting normally |
| 482 | if the control socket does not exist, or is not listening. |
| 483 | .Pp |
Damien Miller | 23f0770 | 2004-06-18 01:19:03 +1000 | [diff] [blame] | 484 | Setting this to |
| 485 | .Dq ask |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 486 | will cause ssh |
Damien Miller | 23f0770 | 2004-06-18 01:19:03 +1000 | [diff] [blame] | 487 | to listen for control connections, but require confirmation using the |
| 488 | .Ev SSH_ASKPASS |
| 489 | program before they are accepted (see |
| 490 | .Xr ssh-add 1 |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 491 | for details). |
Damien Miller | dadfd4d | 2005-05-26 12:07:13 +1000 | [diff] [blame] | 492 | If the |
| 493 | .Cm ControlPath |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 494 | cannot be opened, |
| 495 | ssh will continue without connecting to a master instance. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 496 | .Pp |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 497 | X11 and |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 498 | .Xr ssh-agent 1 |
Damien Miller | 1339002 | 2005-07-06 09:44:19 +1000 | [diff] [blame] | 499 | forwarding is supported over these multiplexed connections, however the |
Darren Tucker | 6355187 | 2005-12-20 16:14:15 +1100 | [diff] [blame] | 500 | display and agent forwarded will be the one belonging to the master |
Damien Miller | fd94fba | 2005-07-06 09:44:59 +1000 | [diff] [blame] | 501 | 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] | 502 | .Pp |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 503 | Two additional options allow for opportunistic multiplexing: try to use a |
| 504 | master connection but fall back to creating a new one if one does not already |
| 505 | exist. |
| 506 | These options are: |
| 507 | .Dq auto |
| 508 | and |
| 509 | .Dq autoask . |
| 510 | The latter requires confirmation like the |
| 511 | .Dq ask |
| 512 | option. |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 513 | .It Cm ControlPath |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 514 | Specify the path to the control socket used for connection sharing as described |
| 515 | in the |
Damien Miller | 0e220db | 2004-06-15 10:34:08 +1000 | [diff] [blame] | 516 | .Cm ControlMaster |
Damien Miller | 8f74c8f | 2005-06-26 08:56:03 +1000 | [diff] [blame] | 517 | section above or the string |
| 518 | .Dq none |
| 519 | to disable connection sharing. |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 520 | In the path, |
Damien Miller | dfc85fa | 2011-05-15 08:44:02 +1000 | [diff] [blame] | 521 | .Ql %L |
| 522 | will be substituted by the first component of the local host name, |
Damien Miller | 3ec54c7 | 2006-03-15 11:30:13 +1100 | [diff] [blame] | 523 | .Ql %l |
Damien Miller | dfc85fa | 2011-05-15 08:44:02 +1000 | [diff] [blame] | 524 | will be substituted by the local host name (including any domain name), |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 525 | .Ql %h |
| 526 | will be substituted by the target host name, |
Damien Miller | 486dd2e | 2011-05-15 08:47:18 +1000 | [diff] [blame] | 527 | .Ql %n |
| 528 | will be substituted by the original target host name |
| 529 | specified on the command line, |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 530 | .Ql %p |
Damien Miller | 5c86ebd | 2013-10-23 16:29:12 +1100 | [diff] [blame] | 531 | the destination port, |
Damien Miller | 6476cad | 2005-06-16 13:18:34 +1000 | [diff] [blame] | 532 | .Ql %r |
Damien Miller | 9c38643 | 2014-07-03 21:27:46 +1000 | [diff] [blame] | 533 | by the remote login username, |
Damien Miller | dfc85fa | 2011-05-15 08:44:02 +1000 | [diff] [blame] | 534 | .Ql %u |
| 535 | by the username of the user running |
Damien Miller | 9c38643 | 2014-07-03 21:27:46 +1000 | [diff] [blame] | 536 | .Xr ssh 1 , and |
Damien Miller | 0f12341 | 2014-07-03 21:28:09 +1000 | [diff] [blame] | 537 | .Ql \&%C |
Damien Miller | 9c38643 | 2014-07-03 21:27:46 +1000 | [diff] [blame] | 538 | by a hash of the concatenation: %l%h%p%r. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 539 | It is recommended that any |
| 540 | .Cm ControlPath |
| 541 | used for opportunistic connection sharing include |
djm@openbsd.org | fc30256 | 2014-11-10 22:25:49 +0000 | [diff] [blame] | 542 | at least %h, %p, and %r (or alternatively %C) and be placed in a directory |
| 543 | that is not writable by other users. |
Damien Miller | d14b1e7 | 2005-06-16 13:19:41 +1000 | [diff] [blame] | 544 | This ensures that shared connections are uniquely identified. |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 545 | .It Cm ControlPersist |
| 546 | When used in conjunction with |
| 547 | .Cm ControlMaster , |
| 548 | specifies that the master connection should remain open |
| 549 | in the background (waiting for future client connections) |
| 550 | after the initial client connection has been closed. |
| 551 | If set to |
| 552 | .Dq no , |
| 553 | then the master connection will not be placed into the background, |
| 554 | and will close as soon as the initial client connection is closed. |
| 555 | If set to |
djm@openbsd.org | fc30256 | 2014-11-10 22:25:49 +0000 | [diff] [blame] | 556 | .Dq yes |
| 557 | or |
| 558 | .Dq 0 , |
Damien Miller | e11e1ea | 2010-08-03 16:04:46 +1000 | [diff] [blame] | 559 | then the master connection will remain in the background indefinitely |
| 560 | (until killed or closed via a mechanism such as the |
| 561 | .Xr ssh 1 |
| 562 | .Dq Fl O No exit |
| 563 | option). |
| 564 | If set to a time in seconds, or a time in any of the formats documented in |
| 565 | .Xr sshd_config 5 , |
| 566 | then the backgrounded master connection will automatically terminate |
| 567 | after it has remained idle (with no client connections) for the |
| 568 | specified time. |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 569 | .It Cm DynamicForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 570 | Specifies that a TCP port on the local machine be forwarded |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 571 | over the secure channel, and the application |
| 572 | protocol is then used to determine where to connect to from the |
| 573 | remote machine. |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 574 | .Pp |
| 575 | The argument must be |
| 576 | .Sm off |
| 577 | .Oo Ar bind_address : Oc Ar port . |
| 578 | .Sm on |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 579 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Darren Tucker | c8d6421 | 2005-10-03 18:13:42 +1000 | [diff] [blame] | 580 | By default, the local port is bound in accordance with the |
| 581 | .Cm GatewayPorts |
| 582 | setting. |
| 583 | However, an explicit |
| 584 | .Ar bind_address |
| 585 | may be used to bind the connection to a specific address. |
| 586 | The |
| 587 | .Ar bind_address |
| 588 | of |
| 589 | .Dq localhost |
| 590 | indicates that the listening port be bound for local use only, while an |
| 591 | empty address or |
| 592 | .Sq * |
| 593 | indicates that the port should be available from all interfaces. |
| 594 | .Pp |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 595 | Currently the SOCKS4 and SOCKS5 protocols are supported, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 596 | .Xr ssh 1 |
Damien Miller | 2234bac | 2004-06-30 22:38:52 +1000 | [diff] [blame] | 597 | will act as a SOCKS server. |
| 598 | Multiple forwardings may be specified, and |
| 599 | additional forwardings can be given on the command line. |
| 600 | Only the superuser can forward privileged ports. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 601 | .It Cm EnableSSHKeysign |
| 602 | Setting this option to |
| 603 | .Dq yes |
| 604 | in the global client configuration file |
| 605 | .Pa /etc/ssh/ssh_config |
| 606 | enables the use of the helper program |
| 607 | .Xr ssh-keysign 8 |
| 608 | during |
| 609 | .Cm HostbasedAuthentication . |
| 610 | The argument must be |
| 611 | .Dq yes |
| 612 | or |
| 613 | .Dq no . |
| 614 | The default is |
| 615 | .Dq no . |
Darren Tucker | f132c67 | 2003-10-15 15:58:18 +1000 | [diff] [blame] | 616 | This option should be placed in the non-hostspecific section. |
Darren Tucker | 674f71d | 2003-06-28 12:33:12 +1000 | [diff] [blame] | 617 | See |
| 618 | .Xr ssh-keysign 8 |
| 619 | for more information. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 620 | .It Cm EscapeChar |
| 621 | Sets the escape character (default: |
| 622 | .Ql ~ ) . |
| 623 | The escape character can also |
| 624 | be set on the command line. |
| 625 | The argument should be a single character, |
| 626 | .Ql ^ |
| 627 | followed by a letter, or |
| 628 | .Dq none |
| 629 | to disable the escape |
| 630 | character entirely (making the connection transparent for binary |
| 631 | data). |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 632 | .It Cm ExitOnForwardFailure |
| 633 | Specifies whether |
| 634 | .Xr ssh 1 |
| 635 | should terminate the connection if it cannot set up all requested |
Darren Tucker | fc5d188 | 2007-08-15 22:20:22 +1000 | [diff] [blame] | 636 | dynamic, tunnel, local, and remote port forwardings. |
Darren Tucker | e7d4b19 | 2006-07-12 22:17:10 +1000 | [diff] [blame] | 637 | The argument must be |
| 638 | .Dq yes |
| 639 | or |
| 640 | .Dq no . |
| 641 | The default is |
| 642 | .Dq no . |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 643 | .It Cm FingerprintHash |
| 644 | Specifies the hash algorithm used when displaying key fingerprints. |
| 645 | Valid options are: |
| 646 | .Dq md5 |
| 647 | and |
| 648 | .Dq sha256 . |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 649 | The default is |
| 650 | .Dq sha256 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 651 | .It Cm ForwardAgent |
| 652 | Specifies whether the connection to the authentication agent (if any) |
| 653 | will be forwarded to the remote machine. |
| 654 | The argument must be |
| 655 | .Dq yes |
| 656 | or |
| 657 | .Dq no . |
| 658 | The default is |
| 659 | .Dq no . |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 660 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 661 | Agent forwarding should be enabled with caution. |
| 662 | Users with the ability to bypass file permissions on the remote host |
| 663 | (for the agent's Unix-domain socket) |
| 664 | can access the local agent through the forwarded connection. |
| 665 | An attacker cannot obtain key material from the agent, |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 666 | however they can perform operations on the keys that enable them to |
| 667 | authenticate using the identities loaded into the agent. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 668 | .It Cm ForwardX11 |
| 669 | Specifies whether X11 connections will be automatically redirected |
| 670 | over the secure channel and |
| 671 | .Ev DISPLAY |
| 672 | set. |
| 673 | The argument must be |
| 674 | .Dq yes |
| 675 | or |
| 676 | .Dq no . |
| 677 | The default is |
| 678 | .Dq no . |
Damien Miller | af65304 | 2002-09-04 16:40:37 +1000 | [diff] [blame] | 679 | .Pp |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 680 | X11 forwarding should be enabled with caution. |
| 681 | Users with the ability to bypass file permissions on the remote host |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 682 | (for the user's X11 authorization database) |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 683 | can access the local X11 display through the forwarded connection. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 684 | An attacker may then be able to perform activities such as keystroke monitoring |
| 685 | if the |
| 686 | .Cm ForwardX11Trusted |
| 687 | option is also enabled. |
Damien Miller | 1ab6a51 | 2010-06-26 10:02:24 +1000 | [diff] [blame] | 688 | .It Cm ForwardX11Timeout |
Damien Miller | cede1db | 2010-07-02 13:33:48 +1000 | [diff] [blame] | 689 | Specify a timeout for untrusted X11 forwarding |
| 690 | using the format described in the |
Damien Miller | fecfd11 | 2013-07-18 16:11:50 +1000 | [diff] [blame] | 691 | TIME FORMATS section of |
Damien Miller | 1ab6a51 | 2010-06-26 10:02:24 +1000 | [diff] [blame] | 692 | .Xr sshd_config 5 . |
| 693 | X11 connections received by |
| 694 | .Xr ssh 1 |
| 695 | after this time will be refused. |
| 696 | The default is to disable untrusted X11 forwarding after twenty minutes has |
| 697 | elapsed. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 698 | .It Cm ForwardX11Trusted |
Darren Tucker | dcf6ec4 | 2004-05-13 13:03:56 +1000 | [diff] [blame] | 699 | If this option is set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 700 | .Dq yes , |
| 701 | remote X11 clients will have full access to the original X11 display. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 702 | .Pp |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 703 | If this option is set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 704 | .Dq no , |
| 705 | remote X11 clients will be considered untrusted and prevented |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 706 | from stealing or tampering with data belonging to trusted X11 |
| 707 | clients. |
Damien Miller | 1717fd4 | 2005-03-01 21:17:31 +1100 | [diff] [blame] | 708 | Furthermore, the |
| 709 | .Xr xauth 1 |
| 710 | token used for the session will be set to expire after 20 minutes. |
| 711 | Remote clients will be refused access after this time. |
Darren Tucker | 0a118da | 2003-10-15 15:54:32 +1000 | [diff] [blame] | 712 | .Pp |
| 713 | The default is |
| 714 | .Dq no . |
| 715 | .Pp |
| 716 | See the X11 SECURITY extension specification for full details on |
| 717 | the restrictions imposed on untrusted clients. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 718 | .It Cm GatewayPorts |
| 719 | Specifies whether remote hosts are allowed to connect to local |
| 720 | forwarded ports. |
| 721 | By default, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 722 | .Xr ssh 1 |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 723 | binds local port forwardings to the loopback address. |
| 724 | This prevents other remote hosts from connecting to forwarded ports. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 725 | .Cm GatewayPorts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 726 | can be used to specify that ssh |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 727 | should bind local port forwardings to the wildcard address, |
| 728 | thus allowing remote hosts to connect to forwarded ports. |
| 729 | The argument must be |
| 730 | .Dq yes |
| 731 | or |
| 732 | .Dq no . |
| 733 | The default is |
| 734 | .Dq no . |
| 735 | .It Cm GlobalKnownHostsFile |
Damien Miller | 295ee63 | 2011-05-29 21:42:31 +1000 | [diff] [blame] | 736 | Specifies one or more files to use for the global |
| 737 | host key database, separated by whitespace. |
| 738 | The default is |
| 739 | .Pa /etc/ssh/ssh_known_hosts , |
| 740 | .Pa /etc/ssh/ssh_known_hosts2 . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 741 | .It Cm GSSAPIAuthentication |
Damien Miller | baafb98 | 2003-12-17 16:32:23 +1100 | [diff] [blame] | 742 | Specifies whether user authentication based on GSSAPI is allowed. |
Damien Miller | c2b9827 | 2003-09-03 12:13:30 +1000 | [diff] [blame] | 743 | The default is |
Darren Tucker | a044f47 | 2003-10-15 15:52:03 +1000 | [diff] [blame] | 744 | .Dq no . |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 745 | Note that this option applies to protocol version 2 only. |
| 746 | .It Cm GSSAPIDelegateCredentials |
| 747 | Forward (delegate) credentials to the server. |
| 748 | The default is |
| 749 | .Dq no . |
| 750 | Note that this option applies to protocol version 2 only. |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 751 | .It Cm HashKnownHosts |
| 752 | Indicates that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 753 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 754 | should hash host names and addresses when they are added to |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 755 | .Pa ~/.ssh/known_hosts . |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 756 | These hashed names may be used normally by |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 757 | .Xr ssh 1 |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 758 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 759 | .Xr sshd 8 , |
Damien Miller | e177615 | 2005-03-01 21:47:37 +1100 | [diff] [blame] | 760 | but they do not reveal identifying information should the file's contents |
| 761 | be disclosed. |
| 762 | The default is |
| 763 | .Dq no . |
Damien Miller | 858bb7d | 2006-08-05 11:34:51 +1000 | [diff] [blame] | 764 | Note that existing names and addresses in known hosts files |
| 765 | will not be converted automatically, |
| 766 | but may be manually hashed using |
Damien Miller | 4b42d7f | 2005-03-01 21:48:35 +1100 | [diff] [blame] | 767 | .Xr ssh-keygen 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 768 | .It Cm HostbasedAuthentication |
| 769 | Specifies whether to try rhosts based authentication with public key |
| 770 | authentication. |
| 771 | The argument must be |
| 772 | .Dq yes |
| 773 | or |
| 774 | .Dq no . |
| 775 | The default is |
| 776 | .Dq no . |
| 777 | This option applies to protocol version 2 only and |
| 778 | is similar to |
| 779 | .Cm RhostsRSAAuthentication . |
| 780 | .It Cm HostKeyAlgorithms |
| 781 | Specifies the protocol version 2 host key algorithms |
| 782 | that the client wants to use in order of preference. |
| 783 | The default for this option is: |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 784 | .Bd -literal -offset 3n |
| 785 | ecdsa-sha2-nistp256-cert-v01@openssh.com, |
| 786 | ecdsa-sha2-nistp384-cert-v01@openssh.com, |
| 787 | ecdsa-sha2-nistp521-cert-v01@openssh.com, |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame] | 788 | ssh-ed25519-cert-v01@openssh.com, |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 789 | ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com, |
| 790 | ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com, |
| 791 | ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, |
Damien Miller | 5be9d9e | 2013-12-07 11:24:01 +1100 | [diff] [blame] | 792 | ssh-ed25519,ssh-rsa,ssh-dss |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 793 | .Ed |
Damien Miller | d925dcd | 2010-12-01 12:21:51 +1100 | [diff] [blame] | 794 | .Pp |
| 795 | If hostkeys are known for the destination host then this default is modified |
| 796 | to prefer their algorithms. |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 797 | .Pp |
| 798 | The list of available key types may also be obtained using the |
| 799 | .Fl Q |
| 800 | option of |
| 801 | .Xr ssh 1 |
| 802 | with an argument of |
| 803 | .Dq key . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 804 | .It Cm HostKeyAlias |
| 805 | Specifies an alias that should be used instead of the |
| 806 | real host name when looking up or saving the host key |
| 807 | in the host key database files. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 808 | This option is useful for tunneling SSH connections |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 809 | or for multiple servers running on a single host. |
| 810 | .It Cm HostName |
| 811 | Specifies the real host name to log into. |
| 812 | This can be used to specify nicknames or abbreviations for hosts. |
Damien Miller | d0244d4 | 2010-07-16 13:56:43 +1000 | [diff] [blame] | 813 | If the hostname contains the character sequence |
| 814 | .Ql %h , |
Damien Miller | 486dd2e | 2011-05-15 08:47:18 +1000 | [diff] [blame] | 815 | then this will be replaced with the host name specified on the command line |
Damien Miller | d0244d4 | 2010-07-16 13:56:43 +1000 | [diff] [blame] | 816 | (this is useful for manipulating unqualified names). |
Damien Miller | ef9f13b | 2014-07-03 21:26:21 +1000 | [diff] [blame] | 817 | The character sequence |
| 818 | .Ql %% |
| 819 | will be replaced by a single |
| 820 | .Ql % |
| 821 | character, which may be used when specifying IPv6 link-local addresses. |
| 822 | .Pp |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 823 | The default is the name given on the command line. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 824 | Numeric IP addresses are also permitted (both on the command line and in |
| 825 | .Cm HostName |
| 826 | specifications). |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 827 | .It Cm IdentitiesOnly |
| 828 | Specifies that |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 829 | .Xr ssh 1 |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 830 | should only use the authentication identity files configured in the |
Damien Miller | 1a81258 | 2004-04-20 20:13:32 +1000 | [diff] [blame] | 831 | .Nm |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 832 | files, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 833 | even if |
| 834 | .Xr ssh-agent 1 |
Damien Miller | cb6b68b | 2012-12-03 09:49:52 +1100 | [diff] [blame] | 835 | or a |
| 836 | .Cm PKCS11Provider |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 837 | offers more identities. |
| 838 | The argument to this keyword must be |
| 839 | .Dq yes |
| 840 | or |
| 841 | .Dq no . |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 842 | This option is intended for situations where ssh-agent |
Damien Miller | bd394c3 | 2004-03-08 23:12:36 +1100 | [diff] [blame] | 843 | offers many different identities. |
| 844 | The default is |
| 845 | .Dq no . |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 846 | .It Cm IdentityFile |
sobrado@openbsd.org | f70b22b | 2014-08-30 15:33:50 +0000 | [diff] [blame] | 847 | Specifies a file from which the user's DSA, ECDSA, Ed25519 or RSA authentication |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 848 | identity is read. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 849 | The default is |
| 850 | .Pa ~/.ssh/identity |
| 851 | for protocol version 1, and |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 852 | .Pa ~/.ssh/id_dsa , |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame] | 853 | .Pa ~/.ssh/id_ecdsa , |
| 854 | .Pa ~/.ssh/id_ed25519 |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 855 | and |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 856 | .Pa ~/.ssh/id_rsa |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 857 | for protocol version 2. |
| 858 | Additionally, any identities represented by the authentication agent |
Damien Miller | 7f2b438 | 2013-07-18 16:10:29 +1000 | [diff] [blame] | 859 | will be used for authentication unless |
| 860 | .Cm IdentitiesOnly |
| 861 | is set. |
Damien Miller | 5059d8d | 2010-03-05 21:31:11 +1100 | [diff] [blame] | 862 | .Xr ssh 1 |
| 863 | will try to load certificate information from the filename obtained by |
| 864 | appending |
| 865 | .Pa -cert.pub |
| 866 | to the path of a specified |
| 867 | .Cm IdentityFile . |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 868 | .Pp |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 869 | The file name may use the tilde |
Damien Miller | c6437cf | 2006-03-31 23:14:41 +1100 | [diff] [blame] | 870 | syntax to refer to a user's home directory or one of the following |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 871 | escape characters: |
| 872 | .Ql %d |
| 873 | (local user's home directory), |
| 874 | .Ql %u |
| 875 | (local user name), |
| 876 | .Ql %l |
| 877 | (local host name), |
| 878 | .Ql %h |
| 879 | (remote host name) or |
Damien Miller | dfc6183 | 2006-03-31 23:14:57 +1100 | [diff] [blame] | 880 | .Ql %r |
Damien Miller | 6b1d53c | 2006-03-31 23:13:21 +1100 | [diff] [blame] | 881 | (remote user name). |
| 882 | .Pp |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 883 | It is possible to have |
| 884 | multiple identity files specified in configuration files; all these |
| 885 | identities will be tried in sequence. |
Damien Miller | 6029e07 | 2011-06-20 14:22:49 +1000 | [diff] [blame] | 886 | Multiple |
| 887 | .Cm IdentityFile |
| 888 | directives will add to the list of identities tried (this behaviour |
| 889 | differs from that of other configuration directives). |
Damien Miller | 7f2b438 | 2013-07-18 16:10:29 +1000 | [diff] [blame] | 890 | .Pp |
| 891 | .Cm IdentityFile |
| 892 | may be used in conjunction with |
| 893 | .Cm IdentitiesOnly |
| 894 | to select which identities in an agent are offered during authentication. |
Darren Tucker | 63e0df2 | 2013-05-16 20:30:31 +1000 | [diff] [blame] | 895 | .It Cm IgnoreUnknown |
| 896 | Specifies a pattern-list of unknown options to be ignored if they are |
| 897 | encountered in configuration parsing. |
| 898 | This may be used to suppress errors if |
| 899 | .Nm |
| 900 | contains options that are unrecognised by |
| 901 | .Xr ssh 1 . |
| 902 | It is recommended that |
| 903 | .Cm IgnoreUnknown |
| 904 | be listed early in the configuration file as it will not be applied |
| 905 | to unknown options that appear before it. |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 906 | .It Cm IPQoS |
| 907 | Specifies the IPv4 type-of-service or DSCP class for connections. |
| 908 | Accepted values are |
| 909 | .Dq af11 , |
| 910 | .Dq af12 , |
| 911 | .Dq af13 , |
Damien Miller | f6e758c | 2011-09-22 21:37:13 +1000 | [diff] [blame] | 912 | .Dq af21 , |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 913 | .Dq af22 , |
| 914 | .Dq af23 , |
| 915 | .Dq af31 , |
| 916 | .Dq af32 , |
| 917 | .Dq af33 , |
| 918 | .Dq af41 , |
| 919 | .Dq af42 , |
| 920 | .Dq af43 , |
| 921 | .Dq cs0 , |
| 922 | .Dq cs1 , |
| 923 | .Dq cs2 , |
| 924 | .Dq cs3 , |
| 925 | .Dq cs4 , |
| 926 | .Dq cs5 , |
| 927 | .Dq cs6 , |
| 928 | .Dq cs7 , |
| 929 | .Dq ef , |
| 930 | .Dq lowdelay , |
| 931 | .Dq throughput , |
| 932 | .Dq reliability , |
| 933 | or a numeric value. |
Damien Miller | 928362d | 2010-12-26 14:26:45 +1100 | [diff] [blame] | 934 | This option may take one or two arguments, separated by whitespace. |
Damien Miller | 0dac6fb | 2010-11-20 15:19:38 +1100 | [diff] [blame] | 935 | If one argument is specified, it is used as the packet class unconditionally. |
| 936 | If two values are specified, the first is automatically selected for |
| 937 | interactive sessions and the second for non-interactive sessions. |
| 938 | The default is |
| 939 | .Dq lowdelay |
| 940 | for interactive sessions and |
| 941 | .Dq throughput |
| 942 | for non-interactive sessions. |
Damien Miller | cfb606c | 2007-10-26 14:24:48 +1000 | [diff] [blame] | 943 | .It Cm KbdInteractiveAuthentication |
| 944 | Specifies whether to use keyboard-interactive authentication. |
| 945 | The argument to this keyword must be |
| 946 | .Dq yes |
| 947 | or |
| 948 | .Dq no . |
| 949 | The default is |
| 950 | .Dq yes . |
Darren Tucker | 636ca90 | 2004-11-05 20:22:00 +1100 | [diff] [blame] | 951 | .It Cm KbdInteractiveDevices |
| 952 | Specifies the list of methods to use in keyboard-interactive authentication. |
| 953 | Multiple method names must be comma-separated. |
| 954 | The default is to use the server specified list. |
Damien Miller | 9cfbaec | 2006-03-15 11:57:55 +1100 | [diff] [blame] | 955 | The methods available vary depending on what the server supports. |
| 956 | For an OpenSSH server, |
| 957 | it may be zero or more of: |
| 958 | .Dq bsdauth , |
| 959 | .Dq pam , |
| 960 | and |
| 961 | .Dq skey . |
Damien Miller | d5f62bf | 2010-09-24 22:11:14 +1000 | [diff] [blame] | 962 | .It Cm KexAlgorithms |
| 963 | Specifies the available KEX (Key Exchange) algorithms. |
| 964 | Multiple algorithms must be comma-separated. |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 965 | The default is: |
| 966 | .Bd -literal -offset indent |
Damien Miller | 0bd8f15 | 2013-11-04 08:55:43 +1100 | [diff] [blame] | 967 | curve25519-sha256@libssh.org, |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 968 | ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521, |
| 969 | diffie-hellman-group-exchange-sha256, |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 970 | diffie-hellman-group14-sha1, |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 971 | diffie-hellman-group-exchange-sha1, |
Damien Miller | 7fe2b1f | 2010-09-24 22:11:53 +1000 | [diff] [blame] | 972 | diffie-hellman-group1-sha1 |
| 973 | .Ed |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 974 | .Pp |
| 975 | The list of available key exchange algorithms may also be obtained using the |
| 976 | .Fl Q |
| 977 | option of |
| 978 | .Xr ssh 1 |
| 979 | with an argument of |
| 980 | .Dq kex . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 981 | .It Cm LocalCommand |
| 982 | Specifies a command to execute on the local machine after successfully |
| 983 | connecting to the server. |
| 984 | 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] | 985 | the user's shell. |
Darren Tucker | f6b01b7 | 2008-06-13 04:56:37 +1000 | [diff] [blame] | 986 | The following escape character substitutions will be performed: |
| 987 | .Ql %d |
| 988 | (local user's home directory), |
| 989 | .Ql %h |
| 990 | (remote host name), |
| 991 | .Ql %l |
| 992 | (local host name), |
| 993 | .Ql %n |
| 994 | (host name as provided on the command line), |
| 995 | .Ql %p |
| 996 | (remote port), |
| 997 | .Ql %r |
| 998 | (remote user name) or |
| 999 | .Ql %u |
Damien Miller | 9c38643 | 2014-07-03 21:27:46 +1000 | [diff] [blame] | 1000 | (local user name) or |
Damien Miller | 0f12341 | 2014-07-03 21:28:09 +1000 | [diff] [blame] | 1001 | .Ql \&%C |
Damien Miller | 9c38643 | 2014-07-03 21:27:46 +1000 | [diff] [blame] | 1002 | by a hash of the concatenation: %l%h%p%r. |
Darren Tucker | 78be8c5 | 2010-01-08 17:05:59 +1100 | [diff] [blame] | 1003 | .Pp |
| 1004 | The command is run synchronously and does not have access to the |
| 1005 | session of the |
| 1006 | .Xr ssh 1 |
| 1007 | that spawned it. |
| 1008 | It should not be used for interactive commands. |
| 1009 | .Pp |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1010 | This directive is ignored unless |
| 1011 | .Cm PermitLocalCommand |
| 1012 | has been enabled. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1013 | .It Cm LocalForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 1014 | Specifies that a TCP port on the local machine be forwarded over |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1015 | 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] | 1016 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1017 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1018 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1019 | .Sm on |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1020 | and the second argument must be |
| 1021 | .Ar host : Ns Ar hostport . |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 1022 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1023 | Multiple forwardings may be specified, and additional forwardings can be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1024 | given on the command line. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1025 | Only the superuser can forward privileged ports. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1026 | By default, the local port is bound in accordance with the |
| 1027 | .Cm GatewayPorts |
| 1028 | setting. |
| 1029 | However, an explicit |
| 1030 | .Ar bind_address |
| 1031 | may be used to bind the connection to a specific address. |
| 1032 | The |
| 1033 | .Ar bind_address |
| 1034 | of |
| 1035 | .Dq localhost |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1036 | indicates that the listening port be bound for local use only, while an |
| 1037 | empty address or |
| 1038 | .Sq * |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1039 | indicates that the port should be available from all interfaces. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1040 | .It Cm LogLevel |
| 1041 | Gives the verbosity level that is used when logging messages from |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1042 | .Xr ssh 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1043 | The possible values are: |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1044 | QUIET, FATAL, ERROR, INFO, VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 1045 | The default is INFO. |
| 1046 | DEBUG and DEBUG1 are equivalent. |
| 1047 | DEBUG2 and DEBUG3 each specify higher levels of verbose output. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1048 | .It Cm MACs |
| 1049 | Specifies the MAC (message authentication code) algorithms |
| 1050 | in order of preference. |
| 1051 | The MAC algorithm is used in protocol version 2 |
| 1052 | for data integrity protection. |
| 1053 | Multiple algorithms must be comma-separated. |
Damien Miller | af43a7a | 2012-12-12 10:46:31 +1100 | [diff] [blame] | 1054 | The algorithms that contain |
| 1055 | .Dq -etm |
| 1056 | calculate the MAC after encryption (encrypt-then-mac). |
| 1057 | These are considered safer and their use recommended. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1058 | The default is: |
Damien Miller | 5e7c30b | 2007-06-11 14:06:32 +1000 | [diff] [blame] | 1059 | .Bd -literal -offset indent |
Damien Miller | af43a7a | 2012-12-12 10:46:31 +1100 | [diff] [blame] | 1060 | umac-64-etm@openssh.com,umac-128-etm@openssh.com, |
| 1061 | hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com, |
Damien Miller | c1621c8 | 2014-04-20 13:22:46 +1000 | [diff] [blame] | 1062 | umac-64@openssh.com,umac-128@openssh.com, |
| 1063 | hmac-sha2-256,hmac-sha2-512, |
| 1064 | hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com, |
| 1065 | hmac-ripemd160-etm@openssh.com, |
| 1066 | hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com, |
| 1067 | hmac-md5,hmac-sha1,hmac-ripemd160, |
Darren Tucker | ecbf14a | 2012-07-02 18:53:37 +1000 | [diff] [blame] | 1068 | hmac-sha1-96,hmac-md5-96 |
Damien Miller | 5e7c30b | 2007-06-11 14:06:32 +1000 | [diff] [blame] | 1069 | .Ed |
djm@openbsd.org | 8f6784f | 2014-12-22 09:05:17 +0000 | [diff] [blame] | 1070 | .Pp |
| 1071 | The list of available MAC algorithms may also be obtained using the |
| 1072 | .Fl Q |
| 1073 | option of |
| 1074 | .Xr ssh 1 |
| 1075 | with an argument of |
| 1076 | .Dq mac . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1077 | .It Cm NoHostAuthenticationForLocalhost |
| 1078 | This option can be used if the home directory is shared across machines. |
| 1079 | In this case localhost will refer to a different machine on each of |
| 1080 | the machines and the user will get many warnings about changed host keys. |
| 1081 | However, this option disables host authentication for localhost. |
| 1082 | The argument to this keyword must be |
| 1083 | .Dq yes |
| 1084 | or |
| 1085 | .Dq no . |
| 1086 | The default is to check the host key for localhost. |
| 1087 | .It Cm NumberOfPasswordPrompts |
| 1088 | Specifies the number of password prompts before giving up. |
| 1089 | The argument to this keyword must be an integer. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1090 | The default is 3. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1091 | .It Cm PasswordAuthentication |
| 1092 | Specifies whether to use password authentication. |
| 1093 | The argument to this keyword must be |
| 1094 | .Dq yes |
| 1095 | or |
| 1096 | .Dq no . |
| 1097 | The default is |
| 1098 | .Dq yes . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1099 | .It Cm PermitLocalCommand |
| 1100 | Allow local command execution via the |
| 1101 | .Ic LocalCommand |
| 1102 | option or using the |
Damien Miller | 4b2319f | 2005-12-13 19:30:27 +1100 | [diff] [blame] | 1103 | .Ic !\& Ns Ar command |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1104 | escape sequence in |
| 1105 | .Xr ssh 1 . |
| 1106 | The argument must be |
| 1107 | .Dq yes |
| 1108 | or |
| 1109 | .Dq no . |
| 1110 | The default is |
| 1111 | .Dq no . |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 1112 | .It Cm PKCS11Provider |
| 1113 | Specifies which PKCS#11 provider to use. |
Damien Miller | 8e1ea4e | 2010-11-20 15:20:10 +1100 | [diff] [blame] | 1114 | The argument to this keyword is the PKCS#11 shared library |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 1115 | .Xr ssh 1 |
Damien Miller | a761844 | 2010-02-12 09:26:02 +1100 | [diff] [blame] | 1116 | should use to communicate with a PKCS#11 token providing the user's |
Damien Miller | 7ea845e | 2010-02-12 09:21:02 +1100 | [diff] [blame] | 1117 | private RSA key. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1118 | .It Cm Port |
| 1119 | Specifies the port number to connect on the remote host. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1120 | The default is 22. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1121 | .It Cm PreferredAuthentications |
| 1122 | Specifies the order in which the client should try protocol 2 |
Damien Miller | fbf486b | 2003-05-23 18:44:23 +1000 | [diff] [blame] | 1123 | authentication methods. |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 1124 | This allows a client to prefer one method (e.g.\& |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1125 | .Cm keyboard-interactive ) |
Darren Tucker | 1adc2bd | 2005-03-14 23:14:20 +1100 | [diff] [blame] | 1126 | over another method (e.g.\& |
Damien Miller | 544378d | 2010-04-16 15:52:24 +1000 | [diff] [blame] | 1127 | .Cm password ) . |
| 1128 | The default is: |
| 1129 | .Bd -literal -offset indent |
| 1130 | gssapi-with-mic,hostbased,publickey, |
| 1131 | keyboard-interactive,password |
| 1132 | .Ed |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1133 | .It Cm Protocol |
| 1134 | Specifies the protocol versions |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1135 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1136 | should support in order of preference. |
| 1137 | The possible values are |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1138 | .Sq 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1139 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1140 | .Sq 2 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1141 | Multiple versions must be comma-separated. |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 1142 | When this option is set to |
Darren Tucker | 7a4a765 | 2009-10-11 21:51:40 +1100 | [diff] [blame] | 1143 | .Dq 2,1 |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 1144 | .Nm ssh |
| 1145 | will try version 2 and fall back to version 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1146 | if version 2 is not available. |
Darren Tucker | bad5076 | 2009-10-11 21:51:08 +1100 | [diff] [blame] | 1147 | The default is |
Darren Tucker | 7a4a765 | 2009-10-11 21:51:40 +1100 | [diff] [blame] | 1148 | .Sq 2 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1149 | .It Cm ProxyCommand |
| 1150 | Specifies the command to use to connect to the server. |
| 1151 | The command |
Damien Miller | 079bac2 | 2014-07-09 13:06:25 +1000 | [diff] [blame] | 1152 | string extends to the end of the line, and is executed |
| 1153 | using the user's shell |
| 1154 | .Ql exec |
| 1155 | directive to avoid a lingering shell process. |
| 1156 | .Pp |
Damien Miller | c4eddee | 2010-04-18 08:07:43 +1000 | [diff] [blame] | 1157 | In the command string, any occurrence of |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1158 | .Ql %h |
| 1159 | will be substituted by the host name to |
Damien Miller | b1b1704 | 2010-04-16 15:54:19 +1000 | [diff] [blame] | 1160 | connect, |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1161 | .Ql %p |
Damien Miller | c4eddee | 2010-04-18 08:07:43 +1000 | [diff] [blame] | 1162 | by the port, and |
| 1163 | .Ql %r |
Damien Miller | b1b1704 | 2010-04-16 15:54:19 +1000 | [diff] [blame] | 1164 | by the remote user name. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1165 | The command can be basically anything, |
| 1166 | and should read from its standard input and write to its standard output. |
| 1167 | It should eventually connect an |
| 1168 | .Xr sshd 8 |
| 1169 | server running on some machine, or execute |
| 1170 | .Ic sshd -i |
| 1171 | somewhere. |
| 1172 | Host key management will be done using the |
| 1173 | HostName of the host being connected (defaulting to the name typed by |
| 1174 | the user). |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 1175 | Setting the command to |
| 1176 | .Dq none |
Damien Miller | 9f1e33a | 2003-02-24 11:57:32 +1100 | [diff] [blame] | 1177 | disables this option entirely. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1178 | Note that |
| 1179 | .Cm CheckHostIP |
| 1180 | is not available for connects with a proxy command. |
| 1181 | .Pp |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 1182 | This directive is useful in conjunction with |
| 1183 | .Xr nc 1 |
| 1184 | and its proxy support. |
Damien Miller | dfec294 | 2005-05-26 12:14:32 +1000 | [diff] [blame] | 1185 | For example, the following directive would connect via an HTTP proxy at |
Damien Miller | ebcfedc | 2005-05-26 12:13:56 +1000 | [diff] [blame] | 1186 | 192.0.2.0: |
| 1187 | .Bd -literal -offset 3n |
| 1188 | ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p |
| 1189 | .Ed |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1190 | .It Cm ProxyUseFdpass |
Damien Miller | f2f6c31 | 2013-08-21 02:44:58 +1000 | [diff] [blame] | 1191 | Specifies that |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1192 | .Cm ProxyCommand |
| 1193 | will pass a connected file descriptor back to |
Damien Miller | f2f6c31 | 2013-08-21 02:44:58 +1000 | [diff] [blame] | 1194 | .Xr ssh 1 |
Damien Miller | 1262b66 | 2013-08-21 02:44:24 +1000 | [diff] [blame] | 1195 | instead of continuing to execute and pass data. |
| 1196 | The default is |
| 1197 | .Dq no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1198 | .It Cm PubkeyAuthentication |
| 1199 | Specifies whether to try public key authentication. |
| 1200 | The argument to this keyword must be |
| 1201 | .Dq yes |
| 1202 | or |
| 1203 | .Dq no . |
| 1204 | The default is |
| 1205 | .Dq yes . |
| 1206 | This option applies to protocol version 2 only. |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1207 | .It Cm RekeyLimit |
| 1208 | Specifies the maximum amount of data that may be transmitted before the |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1209 | session key is renegotiated, optionally followed a maximum amount of |
| 1210 | time that may pass before the session key is renegotiated. |
| 1211 | 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] | 1212 | .Sq K , |
| 1213 | .Sq M , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1214 | or |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 1215 | .Sq G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1216 | to indicate Kilobytes, Megabytes, or Gigabytes, respectively. |
| 1217 | The default is between |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1218 | .Sq 1G |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1219 | and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1220 | .Sq 4G , |
Darren Tucker | 62388b2 | 2006-01-20 11:31:47 +1100 | [diff] [blame] | 1221 | depending on the cipher. |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1222 | The optional second value is specified in seconds and may use any of the |
| 1223 | units documented in the |
Damien Miller | fecfd11 | 2013-07-18 16:11:50 +1000 | [diff] [blame] | 1224 | TIME FORMATS section of |
Darren Tucker | c53c2af | 2013-05-16 20:28:16 +1000 | [diff] [blame] | 1225 | .Xr sshd_config 5 . |
| 1226 | The default value for |
| 1227 | .Cm RekeyLimit |
| 1228 | is |
| 1229 | .Dq default none , |
| 1230 | which means that rekeying is performed after the cipher's default amount |
| 1231 | of data has been sent or received and no time based rekeying is done. |
Damien Miller | ddfddf1 | 2006-01-31 21:39:03 +1100 | [diff] [blame] | 1232 | This option applies to protocol version 2 only. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1233 | .It Cm RemoteForward |
Damien Miller | e9d001e | 2006-01-14 10:10:17 +1100 | [diff] [blame] | 1234 | Specifies that a TCP port on the remote machine be forwarded over |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1235 | the secure channel to the specified host and port from the local machine. |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1236 | The first argument must be |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1237 | .Sm off |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1238 | .Oo Ar bind_address : Oc Ar port |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1239 | .Sm on |
Darren Tucker | 5ede2ad | 2005-03-31 21:31:10 +1000 | [diff] [blame] | 1240 | and the second argument must be |
| 1241 | .Ar host : Ns Ar hostport . |
Damien Miller | 7fa9660 | 2010-08-05 13:03:13 +1000 | [diff] [blame] | 1242 | IPv6 addresses can be specified by enclosing addresses in square brackets. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1243 | Multiple forwardings may be specified, and additional |
| 1244 | forwardings can be given on the command line. |
Damien Miller | de7532e | 2008-11-03 19:24:45 +1100 | [diff] [blame] | 1245 | Privileged ports can be forwarded only when |
| 1246 | logging in as root on the remote machine. |
Damien Miller | e379e10 | 2009-02-14 16:34:39 +1100 | [diff] [blame] | 1247 | .Pp |
Damien Miller | 85c6d8a | 2009-02-14 16:34:21 +1100 | [diff] [blame] | 1248 | If the |
| 1249 | .Ar port |
| 1250 | argument is |
| 1251 | .Ql 0 , |
| 1252 | the listen port will be dynamically allocated on the server and reported |
| 1253 | to the client at run time. |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1254 | .Pp |
| 1255 | If the |
| 1256 | .Ar bind_address |
| 1257 | is not specified, the default is to only bind to loopback addresses. |
| 1258 | If the |
| 1259 | .Ar bind_address |
| 1260 | is |
| 1261 | .Ql * |
| 1262 | or an empty string, then the forwarding is requested to listen on all |
| 1263 | interfaces. |
| 1264 | Specifying a remote |
| 1265 | .Ar bind_address |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1266 | will only succeed if the server's |
| 1267 | .Cm GatewayPorts |
Damien Miller | f91ee4c | 2005-03-01 21:24:33 +1100 | [diff] [blame] | 1268 | option is enabled (see |
Damien Miller | f8c5546 | 2005-03-02 12:03:05 +1100 | [diff] [blame] | 1269 | .Xr sshd_config 5 ) . |
Damien Miller | 21771e2 | 2011-05-15 08:45:50 +1000 | [diff] [blame] | 1270 | .It Cm RequestTTY |
| 1271 | Specifies whether to request a pseudo-tty for the session. |
| 1272 | The argument may be one of: |
| 1273 | .Dq no |
| 1274 | (never request a TTY), |
| 1275 | .Dq yes |
| 1276 | (always request a TTY when standard input is a TTY), |
| 1277 | .Dq force |
| 1278 | (always request a TTY) or |
| 1279 | .Dq auto |
| 1280 | (request a TTY when opening a login session). |
| 1281 | This option mirrors the |
| 1282 | .Fl t |
| 1283 | and |
| 1284 | .Fl T |
| 1285 | flags for |
| 1286 | .Xr ssh 1 . |
djm@openbsd.org | 5e39a49 | 2014-12-04 02:24:32 +0000 | [diff] [blame] | 1287 | .It Cm RevokedHostKeys |
| 1288 | Specifies revoked host public keys. |
| 1289 | Keys listed in this file will be refused for host authentication. |
| 1290 | Note that if this file does not exist or is not readable, |
| 1291 | then host authentication will be refused for all hosts. |
| 1292 | Keys may be specified as a text file, listing one public key per line, or as |
| 1293 | an OpenSSH Key Revocation List (KRL) as generated by |
| 1294 | .Xr ssh-keygen 1 . |
| 1295 | For more information on KRLs, see the KEY REVOCATION LISTS section in |
| 1296 | .Xr ssh-keygen 1 . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1297 | .It Cm RhostsRSAAuthentication |
| 1298 | Specifies whether to try rhosts based authentication with RSA host |
| 1299 | authentication. |
| 1300 | The argument must be |
| 1301 | .Dq yes |
| 1302 | or |
| 1303 | .Dq no . |
| 1304 | The default is |
| 1305 | .Dq no . |
| 1306 | This option applies to protocol version 1 only and requires |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1307 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1308 | to be setuid root. |
| 1309 | .It Cm RSAAuthentication |
| 1310 | Specifies whether to try RSA authentication. |
| 1311 | The argument to this keyword must be |
| 1312 | .Dq yes |
| 1313 | or |
| 1314 | .Dq no . |
| 1315 | RSA authentication will only be |
| 1316 | attempted if the identity file exists, or an authentication agent is |
| 1317 | running. |
| 1318 | The default is |
| 1319 | .Dq yes . |
| 1320 | Note that this option applies to protocol version 1 only. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1321 | .It Cm SendEnv |
| 1322 | Specifies what variables from the local |
| 1323 | .Xr environ 7 |
| 1324 | should be sent to the server. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1325 | Note that environment passing is only supported for protocol 2. |
| 1326 | 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] | 1327 | accept these environment variables. |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1328 | Refer to |
| 1329 | .Cm AcceptEnv |
| 1330 | in |
| 1331 | .Xr sshd_config 5 |
| 1332 | for how to configure the server. |
Damien Miller | 6def551 | 2006-03-15 11:54:05 +1100 | [diff] [blame] | 1333 | Variables are specified by name, which may contain wildcard characters. |
Darren Tucker | 1e0c9bf | 2004-05-02 22:12:48 +1000 | [diff] [blame] | 1334 | Multiple environment variables may be separated by whitespace or spread |
Darren Tucker | 46bc075 | 2004-05-02 22:11:30 +1000 | [diff] [blame] | 1335 | across multiple |
| 1336 | .Cm SendEnv |
| 1337 | directives. |
| 1338 | The default is not to send any environment variables. |
Damien Miller | f54a4b9 | 2006-03-15 11:54:36 +1100 | [diff] [blame] | 1339 | .Pp |
| 1340 | See |
| 1341 | .Sx PATTERNS |
| 1342 | for more information on patterns. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1343 | .It Cm ServerAliveCountMax |
Damien Miller | b797770 | 2006-01-03 18:47:31 +1100 | [diff] [blame] | 1344 | Sets the number of server alive messages (see below) which may be |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1345 | sent without |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1346 | .Xr ssh 1 |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1347 | receiving any messages back from the server. |
| 1348 | If this threshold is reached while server alive messages are being sent, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1349 | ssh will disconnect from the server, terminating the session. |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1350 | It is important to note that the use of server alive messages is very |
| 1351 | different from |
| 1352 | .Cm TCPKeepAlive |
| 1353 | (below). |
| 1354 | The server alive messages are sent through the encrypted channel |
| 1355 | and therefore will not be spoofable. |
| 1356 | The TCP keepalive option enabled by |
| 1357 | .Cm TCPKeepAlive |
| 1358 | is spoofable. |
| 1359 | The server alive mechanism is valuable when the client or |
| 1360 | server depend on knowing when a connection has become inactive. |
| 1361 | .Pp |
| 1362 | The default value is 3. |
| 1363 | If, for example, |
| 1364 | .Cm ServerAliveInterval |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1365 | (see below) is set to 15 and |
Damien Miller | 509b010 | 2003-12-17 16:33:10 +1100 | [diff] [blame] | 1366 | .Cm ServerAliveCountMax |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1367 | is left at the default, if the server becomes unresponsive, |
| 1368 | ssh will disconnect after approximately 45 seconds. |
Damien Miller | cc3e8ba | 2006-03-15 12:06:55 +1100 | [diff] [blame] | 1369 | This option applies to protocol version 2 only. |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1370 | .It Cm ServerAliveInterval |
| 1371 | Sets a timeout interval in seconds after which if no data has been received |
| 1372 | from the server, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1373 | .Xr ssh 1 |
Damien Miller | 957d4e4 | 2005-12-13 19:30:45 +1100 | [diff] [blame] | 1374 | will send a message through the encrypted |
| 1375 | channel to request a response from the server. |
| 1376 | The default |
| 1377 | is 0, indicating that these messages will not be sent to the server. |
| 1378 | This option applies to protocol version 2 only. |
Damien Miller | 7acefbb | 2014-07-18 14:11:24 +1000 | [diff] [blame] | 1379 | .It Cm StreamLocalBindMask |
| 1380 | Sets the octal file creation mode mask |
| 1381 | .Pq umask |
| 1382 | used when creating a Unix-domain socket file for local or remote |
| 1383 | port forwarding. |
| 1384 | This option is only used for port forwarding to a Unix-domain socket file. |
| 1385 | .Pp |
| 1386 | The default value is 0177, which creates a Unix-domain socket file that is |
| 1387 | readable and writable only by the owner. |
| 1388 | Note that not all operating systems honor the file mode on Unix-domain |
| 1389 | socket files. |
| 1390 | .It Cm StreamLocalBindUnlink |
| 1391 | Specifies whether to remove an existing Unix-domain socket file for local |
| 1392 | or remote port forwarding before creating a new one. |
| 1393 | If the socket file already exists and |
| 1394 | .Cm StreamLocalBindUnlink |
| 1395 | is not enabled, |
| 1396 | .Nm ssh |
| 1397 | will be unable to forward the port to the Unix-domain socket file. |
| 1398 | This option is only used for port forwarding to a Unix-domain socket file. |
| 1399 | .Pp |
| 1400 | The argument must be |
| 1401 | .Dq yes |
| 1402 | or |
| 1403 | .Dq no . |
| 1404 | The default is |
| 1405 | .Dq no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1406 | .It Cm StrictHostKeyChecking |
| 1407 | If this flag is set to |
| 1408 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1409 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1410 | will never automatically add host keys to the |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1411 | .Pa ~/.ssh/known_hosts |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1412 | file, and refuses to connect to hosts whose host key has changed. |
| 1413 | This provides maximum protection against trojan horse attacks, |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1414 | though it can be annoying when the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1415 | .Pa /etc/ssh/ssh_known_hosts |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1416 | file is poorly maintained or when connections to new hosts are |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1417 | frequently made. |
| 1418 | This option forces the user to manually |
| 1419 | add all new hosts. |
| 1420 | If this flag is set to |
| 1421 | .Dq no , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1422 | ssh will automatically add new host keys to the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1423 | user known hosts files. |
| 1424 | If this flag is set to |
| 1425 | .Dq ask , |
| 1426 | new host keys |
| 1427 | will be added to the user known host files only after the user |
| 1428 | has confirmed that is what they really want to do, and |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1429 | ssh will refuse to connect to hosts whose host key has changed. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1430 | The host keys of |
| 1431 | known hosts will be verified automatically in all cases. |
| 1432 | The argument must be |
| 1433 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1434 | .Dq no , |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1435 | or |
| 1436 | .Dq ask . |
| 1437 | The default is |
| 1438 | .Dq ask . |
Damien Miller | 12c150e | 2003-12-17 16:31:10 +1100 | [diff] [blame] | 1439 | .It Cm TCPKeepAlive |
| 1440 | Specifies whether the system should send TCP keepalive messages to the |
| 1441 | other side. |
| 1442 | If they are sent, death of the connection or crash of one |
| 1443 | of the machines will be properly noticed. |
| 1444 | However, this means that |
| 1445 | connections will die if the route is down temporarily, and some people |
| 1446 | find it annoying. |
| 1447 | .Pp |
| 1448 | The default is |
| 1449 | .Dq yes |
| 1450 | (to send TCP keepalive messages), and the client will notice |
| 1451 | if the network goes down or the remote host dies. |
| 1452 | This is important in scripts, and many users want it too. |
| 1453 | .Pp |
| 1454 | To disable TCP keepalive messages, the value should be set to |
| 1455 | .Dq no . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1456 | .It Cm Tunnel |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1457 | Request |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1458 | .Xr tun 4 |
Damien Miller | 7746c39 | 2005-12-13 19:33:37 +1100 | [diff] [blame] | 1459 | device forwarding between the client and the server. |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1460 | The argument must be |
Damien Miller | 7b58e80 | 2005-12-13 19:33:19 +1100 | [diff] [blame] | 1461 | .Dq yes , |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1462 | .Dq point-to-point |
| 1463 | (layer 3), |
| 1464 | .Dq ethernet |
| 1465 | (layer 2), |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1466 | or |
| 1467 | .Dq no . |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1468 | Specifying |
| 1469 | .Dq yes |
| 1470 | requests the default tunnel mode, which is |
| 1471 | .Dq point-to-point . |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1472 | The default is |
| 1473 | .Dq no . |
| 1474 | .It Cm TunnelDevice |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1475 | Specifies the |
Damien Miller | d27b947 | 2005-12-13 19:29:02 +1100 | [diff] [blame] | 1476 | .Xr tun 4 |
Damien Miller | 991dba4 | 2006-07-10 20:16:27 +1000 | [diff] [blame] | 1477 | devices to open on the client |
| 1478 | .Pq Ar local_tun |
| 1479 | and the server |
| 1480 | .Pq Ar remote_tun . |
| 1481 | .Pp |
| 1482 | The argument must be |
| 1483 | .Sm off |
| 1484 | .Ar local_tun Op : Ar remote_tun . |
| 1485 | .Sm on |
| 1486 | The devices may be specified by numerical ID or the keyword |
| 1487 | .Dq any , |
| 1488 | which uses the next available tunnel device. |
| 1489 | If |
| 1490 | .Ar remote_tun |
| 1491 | is not specified, it defaults to |
| 1492 | .Dq any . |
| 1493 | The default is |
| 1494 | .Dq any:any . |
Damien Miller | e8cd741 | 2005-12-24 14:55:47 +1100 | [diff] [blame] | 1495 | .It Cm UsePrivilegedPort |
| 1496 | Specifies whether to use a privileged port for outgoing connections. |
| 1497 | The argument must be |
| 1498 | .Dq yes |
| 1499 | or |
| 1500 | .Dq no . |
| 1501 | The default is |
| 1502 | .Dq no . |
| 1503 | If set to |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1504 | .Dq yes , |
| 1505 | .Xr ssh 1 |
Damien Miller | e8cd741 | 2005-12-24 14:55:47 +1100 | [diff] [blame] | 1506 | must be setuid root. |
| 1507 | Note that this option must be set to |
| 1508 | .Dq yes |
| 1509 | for |
| 1510 | .Cm RhostsRSAAuthentication |
| 1511 | with older servers. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1512 | .It Cm User |
| 1513 | Specifies the user to log in as. |
| 1514 | This can be useful when a different user name is used on different machines. |
| 1515 | This saves the trouble of |
| 1516 | having to remember to give the user name on the command line. |
| 1517 | .It Cm UserKnownHostsFile |
Damien Miller | 295ee63 | 2011-05-29 21:42:31 +1000 | [diff] [blame] | 1518 | Specifies one or more files to use for the user |
| 1519 | host key database, separated by whitespace. |
| 1520 | The default is |
| 1521 | .Pa ~/.ssh/known_hosts , |
| 1522 | .Pa ~/.ssh/known_hosts2 . |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1523 | .It Cm VerifyHostKeyDNS |
| 1524 | Specifies whether to verify the remote key using DNS and SSHFP resource |
| 1525 | records. |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1526 | If this option is set to |
| 1527 | .Dq yes , |
Damien Miller | fe44847 | 2003-11-17 21:19:49 +1100 | [diff] [blame] | 1528 | the client will implicitly trust keys that match a secure fingerprint |
Damien Miller | 150b557 | 2003-11-17 21:19:29 +1100 | [diff] [blame] | 1529 | from DNS. |
| 1530 | Insecure fingerprints will be handled as if this option was set to |
| 1531 | .Dq ask . |
| 1532 | If this option is set to |
| 1533 | .Dq ask , |
| 1534 | information on fingerprint match will be displayed, but the user will still |
| 1535 | need to confirm new host keys according to the |
| 1536 | .Cm StrictHostKeyChecking |
| 1537 | option. |
| 1538 | The argument must be |
| 1539 | .Dq yes , |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1540 | .Dq no , |
Damien Miller | fe44847 | 2003-11-17 21:19:49 +1100 | [diff] [blame] | 1541 | or |
| 1542 | .Dq ask . |
Damien Miller | 37876e9 | 2003-05-15 10:19:46 +1000 | [diff] [blame] | 1543 | The default is |
| 1544 | .Dq no . |
Damien Miller | eacbb4f | 2003-06-02 19:10:41 +1000 | [diff] [blame] | 1545 | Note that this option applies to protocol version 2 only. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1546 | .Pp |
Damien Miller | fecfd11 | 2013-07-18 16:11:50 +1000 | [diff] [blame] | 1547 | See also VERIFYING HOST KEYS in |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1548 | .Xr ssh 1 . |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1549 | .It Cm VisualHostKey |
| 1550 | If this flag is set to |
| 1551 | .Dq yes , |
| 1552 | an ASCII art representation of the remote host key fingerprint is |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 1553 | printed in addition to the fingerprint string at login and |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1554 | for unknown host keys. |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1555 | If this flag is set to |
| 1556 | .Dq no , |
Damien Miller | a414cd3 | 2008-11-03 19:25:21 +1100 | [diff] [blame] | 1557 | no fingerprint strings are printed at login and |
djm@openbsd.org | b79efde | 2014-12-21 23:12:42 +0000 | [diff] [blame] | 1558 | only the fingerprint string will be printed for unknown host keys. |
Damien Miller | 1028824 | 2008-06-30 00:04:03 +1000 | [diff] [blame] | 1559 | The default is |
| 1560 | .Dq no . |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1561 | .It Cm XAuthLocation |
Damien Miller | 05913ba | 2002-09-04 16:51:03 +1000 | [diff] [blame] | 1562 | Specifies the full pathname of the |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1563 | .Xr xauth 1 |
| 1564 | program. |
| 1565 | The default is |
| 1566 | .Pa /usr/X11R6/bin/xauth . |
| 1567 | .El |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1568 | .Sh PATTERNS |
| 1569 | A |
| 1570 | .Em pattern |
| 1571 | consists of zero or more non-whitespace characters, |
| 1572 | .Sq * |
| 1573 | (a wildcard that matches zero or more characters), |
| 1574 | or |
| 1575 | .Sq ?\& |
| 1576 | (a wildcard that matches exactly one character). |
| 1577 | For example, to specify a set of declarations for any host in the |
| 1578 | .Dq .co.uk |
| 1579 | set of domains, |
| 1580 | the following pattern could be used: |
| 1581 | .Pp |
| 1582 | .Dl Host *.co.uk |
| 1583 | .Pp |
| 1584 | The following pattern |
| 1585 | would match any host in the 192.168.0.[0-9] network range: |
| 1586 | .Pp |
| 1587 | .Dl Host 192.168.0.? |
| 1588 | .Pp |
| 1589 | A |
| 1590 | .Em pattern-list |
| 1591 | is a comma-separated list of patterns. |
| 1592 | Patterns within pattern-lists may be negated |
| 1593 | by preceding them with an exclamation mark |
| 1594 | .Pq Sq !\& . |
| 1595 | For example, |
Damien Miller | 51682fa | 2013-10-17 11:48:31 +1100 | [diff] [blame] | 1596 | to allow a key to be used from anywhere within an organization |
Damien Miller | b5282c2 | 2006-03-15 11:59:08 +1100 | [diff] [blame] | 1597 | except from the |
| 1598 | .Dq dialup |
| 1599 | pool, |
| 1600 | the following entry (in authorized_keys) could be used: |
| 1601 | .Pp |
| 1602 | .Dl from=\&"!*.dialup.example.com,*.example.com\&" |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1603 | .Sh FILES |
| 1604 | .Bl -tag -width Ds |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 1605 | .It Pa ~/.ssh/config |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1606 | This is the per-user configuration file. |
| 1607 | The format of this file is described above. |
Damien Miller | 45ee2b9 | 2006-03-15 11:56:18 +1100 | [diff] [blame] | 1608 | This file is used by the SSH client. |
Damien Miller | c970cb9 | 2004-04-20 20:12:53 +1000 | [diff] [blame] | 1609 | Because of the potential for abuse, this file must have strict permissions: |
| 1610 | read/write for the user, and not accessible by others. |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1611 | .It Pa /etc/ssh/ssh_config |
| 1612 | Systemwide configuration file. |
| 1613 | This file provides defaults for those |
| 1614 | values that are not specified in the user's configuration file, and |
| 1615 | for those users who do not have a configuration file. |
| 1616 | This file must be world-readable. |
| 1617 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 1618 | .Sh SEE ALSO |
| 1619 | .Xr ssh 1 |
Ben Lindstrom | 9f04903 | 2002-06-21 00:59:05 +0000 | [diff] [blame] | 1620 | .Sh AUTHORS |
| 1621 | OpenSSH is a derivative of the original and free |
| 1622 | ssh 1.2.12 release by Tatu Ylonen. |
| 1623 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, |
| 1624 | Theo de Raadt and Dug Song |
| 1625 | removed many bugs, re-added newer features and |
| 1626 | created OpenSSH. |
| 1627 | Markus Friedl contributed the support for SSH |
| 1628 | protocol versions 1.5 and 2.0. |