djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 1 | .\" $OpenBSD: ssh-agent.1,v 1.65 2019/10/31 21:22:01 djm Exp $ |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 2 | .\" |
| 3 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 4 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 5 | .\" All rights reserved |
| 6 | .\" |
Damien Miller | e4340be | 2000-09-16 13:29:08 +1100 | [diff] [blame] | 7 | .\" As far as I am concerned, the code I have written for this software |
| 8 | .\" can be used freely for any purpose. Any derived versions of this |
| 9 | .\" software must be clearly marked as such, and if the derived work is |
| 10 | .\" incompatible with the protocol description in the RFC file, it must be |
| 11 | .\" called by a name other than "ssh" or "Secure Shell". |
| 12 | .\" |
Ben Lindstrom | 92a2e38 | 2001-03-05 06:59:27 +0000 | [diff] [blame] | 13 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. |
| 14 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. |
| 15 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. |
Damien Miller | e4340be | 2000-09-16 13:29:08 +1100 | [diff] [blame] | 16 | .\" |
| 17 | .\" Redistribution and use in source and binary forms, with or without |
| 18 | .\" modification, are permitted provided that the following conditions |
| 19 | .\" are met: |
| 20 | .\" 1. Redistributions of source code must retain the above copyright |
| 21 | .\" notice, this list of conditions and the following disclaimer. |
| 22 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| 23 | .\" notice, this list of conditions and the following disclaimer in the |
| 24 | .\" documentation and/or other materials provided with the distribution. |
| 25 | .\" |
| 26 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 27 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 28 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 29 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 30 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 31 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 32 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 33 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 34 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 35 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 36 | .\" |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 37 | .Dd $Mdocdate: October 31 2019 $ |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 38 | .Dt SSH-AGENT 1 |
| 39 | .Os |
| 40 | .Sh NAME |
| 41 | .Nm ssh-agent |
| 42 | .Nd authentication agent |
| 43 | .Sh SYNOPSIS |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 44 | .Nm ssh-agent |
Damien Miller | de735ea | 2010-09-10 11:12:38 +1000 | [diff] [blame] | 45 | .Op Fl c | s |
jmc@openbsd.org | 1a11670 | 2015-11-15 23:54:15 +0000 | [diff] [blame] | 46 | .Op Fl \&Dd |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 47 | .Op Fl a Ar bind_address |
djm@openbsd.org | 56d1c83 | 2014-12-21 22:27:55 +0000 | [diff] [blame] | 48 | .Op Fl E Ar fingerprint_hash |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 49 | .Op Fl P Ar provider_whitelist |
jmc@openbsd.org | 5d33313 | 2016-11-30 06:54:26 +0000 | [diff] [blame] | 50 | .Op Fl t Ar life |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 51 | .Op Ar command Op Ar arg ... |
Ben Lindstrom | 1492029 | 2000-11-21 21:24:55 +0000 | [diff] [blame] | 52 | .Nm ssh-agent |
Damien Miller | de735ea | 2010-09-10 11:12:38 +1000 | [diff] [blame] | 53 | .Op Fl c | s |
Ben Lindstrom | 1492029 | 2000-11-21 21:24:55 +0000 | [diff] [blame] | 54 | .Fl k |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 55 | .Sh DESCRIPTION |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 56 | .Nm |
Damien Miller | ad833b3 | 2000-08-23 10:46:23 +1000 | [diff] [blame] | 57 | is a program to hold private keys used for public key authentication |
sobrado@openbsd.org | f70b22b | 2014-08-30 15:33:50 +0000 | [diff] [blame] | 58 | (RSA, DSA, ECDSA, Ed25519). |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 59 | .Nm |
Damien Miller | 8c492da | 2014-04-20 13:25:09 +1000 | [diff] [blame] | 60 | is usually started in the beginning of an X-session or a login session, and |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 61 | all other windows or programs are started as clients to the ssh-agent |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 62 | program. |
| 63 | Through use of environment variables the agent can be located |
Damien Miller | ad833b3 | 2000-08-23 10:46:23 +1000 | [diff] [blame] | 64 | and automatically used for authentication when logging in to other |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 65 | machines using |
| 66 | .Xr ssh 1 . |
| 67 | .Pp |
Damien Miller | 8c492da | 2014-04-20 13:25:09 +1000 | [diff] [blame] | 68 | The agent initially does not have any private keys. |
| 69 | Keys are added using |
jcs@openbsd.org | f361df4 | 2015-11-15 22:26:49 +0000 | [diff] [blame] | 70 | .Xr ssh 1 |
| 71 | (see |
| 72 | .Cm AddKeysToAgent |
| 73 | in |
| 74 | .Xr ssh_config 5 |
| 75 | for details) |
| 76 | or |
Damien Miller | 8c492da | 2014-04-20 13:25:09 +1000 | [diff] [blame] | 77 | .Xr ssh-add 1 . |
| 78 | Multiple identities may be stored in |
| 79 | .Nm |
| 80 | concurrently and |
| 81 | .Xr ssh 1 |
| 82 | will automatically use them if present. |
| 83 | .Xr ssh-add 1 |
| 84 | is also used to remove keys from |
| 85 | .Nm |
| 86 | and to query the keys that are held in one. |
| 87 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 88 | The options are as follows: |
| 89 | .Bl -tag -width Ds |
Ben Lindstrom | b7788f3 | 2002-06-06 21:46:08 +0000 | [diff] [blame] | 90 | .It Fl a Ar bind_address |
Darren Tucker | ae69e1d | 2009-10-24 11:41:34 +1100 | [diff] [blame] | 91 | Bind the agent to the |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 92 | .Ux Ns -domain |
| 93 | socket |
Ben Lindstrom | b7788f3 | 2002-06-06 21:46:08 +0000 | [diff] [blame] | 94 | .Ar bind_address . |
| 95 | The default is |
Damien Miller | 2cd6293 | 2010-12-01 11:50:35 +1100 | [diff] [blame] | 96 | .Pa $TMPDIR/ssh-XXXXXXXXXX/agent.\*(Ltppid\*(Gt . |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 97 | .It Fl c |
| 98 | Generate C-shell commands on |
| 99 | .Dv stdout . |
| 100 | This is the default if |
| 101 | .Ev SHELL |
| 102 | looks like it's a csh style of shell. |
djm@openbsd.org | 2ea9746 | 2015-04-24 05:26:44 +0000 | [diff] [blame] | 103 | .It Fl D |
| 104 | Foreground mode. |
| 105 | When this option is specified |
| 106 | .Nm |
| 107 | will not fork. |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 108 | .It Fl d |
| 109 | Debug mode. |
| 110 | When this option is specified |
| 111 | .Nm |
djm@openbsd.org | 2ea9746 | 2015-04-24 05:26:44 +0000 | [diff] [blame] | 112 | will not fork and will write debug information to standard error. |
djm@openbsd.org | 56d1c83 | 2014-12-21 22:27:55 +0000 | [diff] [blame] | 113 | .It Fl E Ar fingerprint_hash |
| 114 | Specifies the hash algorithm used when displaying key fingerprints. |
| 115 | Valid options are: |
| 116 | .Dq md5 |
| 117 | and |
| 118 | .Dq sha256 . |
| 119 | The default is |
| 120 | .Dq sha256 . |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 121 | .It Fl k |
| 122 | Kill the current agent (given by the |
| 123 | .Ev SSH_AGENT_PID |
| 124 | environment variable). |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 125 | .It Fl P Ar provider_whitelist |
| 126 | Specify a pattern-list of acceptable paths for PKCS#11 and security key shared |
| 127 | libraries that may be used with the |
djm@openbsd.org | 786d599 | 2016-11-30 03:07:37 +0000 | [diff] [blame] | 128 | .Fl s |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 129 | or |
| 130 | .Fl S |
| 131 | options to |
djm@openbsd.org | 786d599 | 2016-11-30 03:07:37 +0000 | [diff] [blame] | 132 | .Xr ssh-add 1 . |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 133 | The default is to allow loading libraries from |
djm@openbsd.org | 786d599 | 2016-11-30 03:07:37 +0000 | [diff] [blame] | 134 | .Dq /usr/lib/*,/usr/local/lib/* . |
djm@openbsd.org | 07da39f | 2019-10-31 21:22:01 +0000 | [diff] [blame] | 135 | Libraries that do not match the whitelist will be refused. |
djm@openbsd.org | 786d599 | 2016-11-30 03:07:37 +0000 | [diff] [blame] | 136 | See PATTERNS in |
| 137 | .Xr ssh_config 5 |
| 138 | for a description of pattern-list syntax. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 139 | .It Fl s |
| 140 | Generate Bourne shell commands on |
| 141 | .Dv stdout . |
| 142 | This is the default if |
| 143 | .Ev SHELL |
| 144 | does not look like it's a csh style of shell. |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 145 | .It Fl t Ar life |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 146 | Set a default value for the maximum lifetime of identities added to the agent. |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 147 | The lifetime may be specified in seconds or in a time format specified in |
Darren Tucker | 3a4634f | 2005-11-28 17:05:40 +1100 | [diff] [blame] | 148 | .Xr sshd_config 5 . |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 149 | A lifetime specified for an identity with |
| 150 | .Xr ssh-add 1 |
| 151 | overrides this value. |
| 152 | Without this option the default maximum lifetime is forever. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 153 | .El |
| 154 | .Pp |
jmc@openbsd.org | 8b29008 | 2015-11-05 09:48:05 +0000 | [diff] [blame] | 155 | If a command line is given, this is executed as a subprocess of the agent. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 156 | When the command dies, so does the agent. |
| 157 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 158 | The idea is that the agent is run in the user's local PC, laptop, or |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 159 | terminal. |
| 160 | Authentication data need not be stored on any other |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 161 | machine, and authentication passphrases never go over the network. |
| 162 | However, the connection to the agent is forwarded over SSH |
| 163 | remote logins, and the user can thus use the privileges given by the |
| 164 | identities anywhere in the network in a secure way. |
| 165 | .Pp |
Damien Miller | abbae98 | 2003-05-15 10:16:21 +1000 | [diff] [blame] | 166 | There are two main ways to get an agent set up: |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 167 | The first is that the agent starts a new subcommand into which some environment |
| 168 | variables are exported, eg |
| 169 | .Cm ssh-agent xterm & . |
| 170 | The second is that the agent prints the needed shell commands (either |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 171 | .Xr sh 1 |
| 172 | or |
| 173 | .Xr csh 1 |
Darren Tucker | 5837b51 | 2009-06-21 17:52:27 +1000 | [diff] [blame] | 174 | syntax can be generated) which can be evaluated in the calling shell, eg |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 175 | .Cm eval `ssh-agent -s` |
| 176 | for Bourne-type shells such as |
| 177 | .Xr sh 1 |
| 178 | or |
| 179 | .Xr ksh 1 |
| 180 | and |
Darren Tucker | fc95970 | 2004-07-17 16:12:08 +1000 | [diff] [blame] | 181 | .Cm eval `ssh-agent -c` |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 182 | for |
| 183 | .Xr csh 1 |
| 184 | and derivatives. |
| 185 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 186 | Later |
| 187 | .Xr ssh 1 |
Ben Lindstrom | 0d3e8fa | 2001-04-04 01:51:25 +0000 | [diff] [blame] | 188 | looks at these variables and uses them to establish a connection to the agent. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 189 | .Pp |
Ben Lindstrom | 11f790b | 2001-12-06 16:37:51 +0000 | [diff] [blame] | 190 | The agent will never send a private key over its request channel. |
| 191 | Instead, operations that require a private key will be performed |
| 192 | by the agent, and the result will be returned to the requester. |
| 193 | This way, private keys are not exposed to clients using the agent. |
| 194 | .Pp |
Darren Tucker | ae69e1d | 2009-10-24 11:41:34 +1100 | [diff] [blame] | 195 | A |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 196 | .Ux Ns -domain |
| 197 | socket is created and the name of this socket is stored in the |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 198 | .Ev SSH_AUTH_SOCK |
| 199 | environment |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 200 | variable. |
| 201 | The socket is made accessible only to the current user. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 202 | This method is easily abused by root or another instance of the same |
| 203 | user. |
| 204 | .Pp |
| 205 | The |
| 206 | .Ev SSH_AGENT_PID |
Ben Lindstrom | 959de99 | 2002-06-23 00:35:25 +0000 | [diff] [blame] | 207 | environment variable holds the agent's process ID. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 208 | .Pp |
| 209 | The agent exits automatically when the command given on the command |
| 210 | line terminates. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 211 | .Sh FILES |
| 212 | .Bl -tag -width Ds |
jmc@openbsd.org | 5d33313 | 2016-11-30 06:54:26 +0000 | [diff] [blame] | 213 | .It Pa $TMPDIR/ssh-XXXXXXXXXX/agent.<ppid> |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 214 | .Ux Ns -domain |
| 215 | sockets used to contain the connection to the authentication agent. |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 216 | These sockets should only be readable by the owner. |
| 217 | The sockets should get automatically removed when the agent exits. |
Damien Miller | 3702396 | 2000-07-11 17:31:38 +1000 | [diff] [blame] | 218 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 219 | .Sh SEE ALSO |
| 220 | .Xr ssh 1 , |
| 221 | .Xr ssh-add 1 , |
| 222 | .Xr ssh-keygen 1 , |
| 223 | .Xr sshd 8 |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 224 | .Sh AUTHORS |
jmc@openbsd.org | 5d33313 | 2016-11-30 06:54:26 +0000 | [diff] [blame] | 225 | .An -nosplit |
| 226 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by |
| 227 | .An Tatu Ylonen . |
| 228 | .An Aaron Campbell , Bob Beck , Markus Friedl , Niels Provos , Theo de Raadt |
| 229 | and |
| 230 | .An Dug Song |
| 231 | removed many bugs, re-added newer features and created OpenSSH. |
| 232 | .An Markus Friedl |
| 233 | contributed the support for SSH protocol versions 1.5 and 2.0. |