Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame^] | 1 | .\" $OpenBSD: ssh-agent.1,v 1.54 2013/12/07 11:58:46 naddy 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 | .\" |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame^] | 37 | .Dd $Mdocdate: December 7 2013 $ |
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 |
Ben Lindstrom | ba1fa1d | 2001-09-12 17:02:49 +0000 | [diff] [blame] | 46 | .Op Fl d |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 47 | .Op Fl a Ar bind_address |
| 48 | .Op Fl t Ar life |
| 49 | .Op Ar command Op Ar arg ... |
Ben Lindstrom | 1492029 | 2000-11-21 21:24:55 +0000 | [diff] [blame] | 50 | .Nm ssh-agent |
Damien Miller | de735ea | 2010-09-10 11:12:38 +1000 | [diff] [blame] | 51 | .Op Fl c | s |
Ben Lindstrom | 1492029 | 2000-11-21 21:24:55 +0000 | [diff] [blame] | 52 | .Fl k |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 53 | .Sh DESCRIPTION |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 54 | .Nm |
Damien Miller | ad833b3 | 2000-08-23 10:46:23 +1000 | [diff] [blame] | 55 | is a program to hold private keys used for public key authentication |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame^] | 56 | (RSA, DSA, ECDSA, ED25519). |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 57 | The idea is that |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 58 | .Nm |
| 59 | is started in the beginning of an X-session or a login session, and |
| 60 | 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] | 61 | program. |
| 62 | Through use of environment variables the agent can be located |
Damien Miller | ad833b3 | 2000-08-23 10:46:23 +1000 | [diff] [blame] | 63 | and automatically used for authentication when logging in to other |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 64 | machines using |
| 65 | .Xr ssh 1 . |
| 66 | .Pp |
| 67 | The options are as follows: |
| 68 | .Bl -tag -width Ds |
Ben Lindstrom | b7788f3 | 2002-06-06 21:46:08 +0000 | [diff] [blame] | 69 | .It Fl a Ar bind_address |
Darren Tucker | ae69e1d | 2009-10-24 11:41:34 +1100 | [diff] [blame] | 70 | Bind the agent to the |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 71 | .Ux Ns -domain |
| 72 | socket |
Ben Lindstrom | b7788f3 | 2002-06-06 21:46:08 +0000 | [diff] [blame] | 73 | .Ar bind_address . |
| 74 | The default is |
Damien Miller | 2cd6293 | 2010-12-01 11:50:35 +1100 | [diff] [blame] | 75 | .Pa $TMPDIR/ssh-XXXXXXXXXX/agent.\*(Ltppid\*(Gt . |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 76 | .It Fl c |
| 77 | Generate C-shell commands on |
| 78 | .Dv stdout . |
| 79 | This is the default if |
| 80 | .Ev SHELL |
| 81 | looks like it's a csh style of shell. |
Damien Miller | 5cbe7ca | 2007-09-17 16:05:50 +1000 | [diff] [blame] | 82 | .It Fl d |
| 83 | Debug mode. |
| 84 | When this option is specified |
| 85 | .Nm |
| 86 | will not fork. |
| 87 | .It Fl k |
| 88 | Kill the current agent (given by the |
| 89 | .Ev SSH_AGENT_PID |
| 90 | environment variable). |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 91 | .It Fl s |
| 92 | Generate Bourne shell commands on |
| 93 | .Dv stdout . |
| 94 | This is the default if |
| 95 | .Ev SHELL |
| 96 | does not look like it's a csh style of shell. |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 97 | .It Fl t Ar life |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 98 | 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] | 99 | 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] | 100 | .Xr sshd_config 5 . |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 101 | A lifetime specified for an identity with |
| 102 | .Xr ssh-add 1 |
| 103 | overrides this value. |
| 104 | Without this option the default maximum lifetime is forever. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 105 | .El |
| 106 | .Pp |
| 107 | If a commandline is given, this is executed as a subprocess of the agent. |
| 108 | When the command dies, so does the agent. |
| 109 | .Pp |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 110 | The agent initially does not have any private keys. |
| 111 | Keys are added using |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 112 | .Xr ssh-add 1 . |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 113 | When executed without arguments, |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 114 | .Xr ssh-add 1 |
Damien Miller | d2b8f16 | 2002-02-05 12:24:19 +1100 | [diff] [blame] | 115 | adds the files |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 116 | .Pa ~/.ssh/id_rsa , |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 117 | .Pa ~/.ssh/id_dsa , |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame^] | 118 | .Pa ~/.ssh/id_ecdsa , |
| 119 | .Pa ~/.ssh/id_ed25519 |
Damien Miller | d2b8f16 | 2002-02-05 12:24:19 +1100 | [diff] [blame] | 120 | and |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 121 | .Pa ~/.ssh/identity . |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 122 | If the identity has a passphrase, |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 123 | .Xr ssh-add 1 |
Damien Miller | 2e68d79 | 2010-01-26 12:51:13 +1100 | [diff] [blame] | 124 | asks for the passphrase on the terminal if it has one or from a small X11 |
| 125 | program if running under X11. |
| 126 | If neither of these is the case then the authentication will fail. |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 127 | It then sends the identity to the agent. |
| 128 | Several identities can be stored in the |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 129 | agent; the agent can automatically use any of these identities. |
| 130 | .Ic ssh-add -l |
| 131 | displays the identities currently held by the agent. |
| 132 | .Pp |
| 133 | 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] | 134 | terminal. |
| 135 | Authentication data need not be stored on any other |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 136 | machine, and authentication passphrases never go over the network. |
| 137 | However, the connection to the agent is forwarded over SSH |
| 138 | remote logins, and the user can thus use the privileges given by the |
| 139 | identities anywhere in the network in a secure way. |
| 140 | .Pp |
Damien Miller | abbae98 | 2003-05-15 10:16:21 +1000 | [diff] [blame] | 141 | There are two main ways to get an agent set up: |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 142 | The first is that the agent starts a new subcommand into which some environment |
| 143 | variables are exported, eg |
| 144 | .Cm ssh-agent xterm & . |
| 145 | The second is that the agent prints the needed shell commands (either |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 146 | .Xr sh 1 |
| 147 | or |
| 148 | .Xr csh 1 |
Darren Tucker | 5837b51 | 2009-06-21 17:52:27 +1000 | [diff] [blame] | 149 | 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] | 150 | .Cm eval `ssh-agent -s` |
| 151 | for Bourne-type shells such as |
| 152 | .Xr sh 1 |
| 153 | or |
| 154 | .Xr ksh 1 |
| 155 | and |
Darren Tucker | fc95970 | 2004-07-17 16:12:08 +1000 | [diff] [blame] | 156 | .Cm eval `ssh-agent -c` |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 157 | for |
| 158 | .Xr csh 1 |
| 159 | and derivatives. |
| 160 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 161 | Later |
| 162 | .Xr ssh 1 |
Ben Lindstrom | 0d3e8fa | 2001-04-04 01:51:25 +0000 | [diff] [blame] | 163 | 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] | 164 | .Pp |
Ben Lindstrom | 11f790b | 2001-12-06 16:37:51 +0000 | [diff] [blame] | 165 | The agent will never send a private key over its request channel. |
| 166 | Instead, operations that require a private key will be performed |
| 167 | by the agent, and the result will be returned to the requester. |
| 168 | This way, private keys are not exposed to clients using the agent. |
| 169 | .Pp |
Darren Tucker | ae69e1d | 2009-10-24 11:41:34 +1100 | [diff] [blame] | 170 | A |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 171 | .Ux Ns -domain |
| 172 | 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] | 173 | .Ev SSH_AUTH_SOCK |
| 174 | environment |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 175 | variable. |
| 176 | The socket is made accessible only to the current user. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 177 | This method is easily abused by root or another instance of the same |
| 178 | user. |
| 179 | .Pp |
| 180 | The |
| 181 | .Ev SSH_AGENT_PID |
Ben Lindstrom | 959de99 | 2002-06-23 00:35:25 +0000 | [diff] [blame] | 182 | environment variable holds the agent's process ID. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 183 | .Pp |
| 184 | The agent exits automatically when the command given on the command |
| 185 | line terminates. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 186 | .Sh FILES |
| 187 | .Bl -tag -width Ds |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 188 | .It Pa ~/.ssh/identity |
Ben Lindstrom | 18a82ac | 2001-04-11 15:59:35 +0000 | [diff] [blame] | 189 | Contains the protocol version 1 RSA authentication identity of the user. |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 190 | .It Pa ~/.ssh/id_dsa |
Ben Lindstrom | 18a82ac | 2001-04-11 15:59:35 +0000 | [diff] [blame] | 191 | Contains the protocol version 2 DSA authentication identity of the user. |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 192 | .It Pa ~/.ssh/id_ecdsa |
| 193 | Contains the protocol version 2 ECDSA authentication identity of the user. |
Damien Miller | 8ba0ead | 2013-12-18 17:46:27 +1100 | [diff] [blame^] | 194 | .It Pa ~/.ssh/id_ed25519 |
| 195 | Contains the protocol version 2 ED25519 authentication identity of the user. |
Damien Miller | 167ea5d | 2005-05-26 12:04:02 +1000 | [diff] [blame] | 196 | .It Pa ~/.ssh/id_rsa |
Ben Lindstrom | 18a82ac | 2001-04-11 15:59:35 +0000 | [diff] [blame] | 197 | Contains the protocol version 2 RSA authentication identity of the user. |
Damien Miller | 2cd6293 | 2010-12-01 11:50:35 +1100 | [diff] [blame] | 198 | .It Pa $TMPDIR/ssh-XXXXXXXXXX/agent.\*(Ltppid\*(Gt |
Darren Tucker | 98c9aec | 2009-10-24 11:42:44 +1100 | [diff] [blame] | 199 | .Ux Ns -domain |
| 200 | sockets used to contain the connection to the authentication agent. |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 201 | These sockets should only be readable by the owner. |
| 202 | The sockets should get automatically removed when the agent exits. |
Damien Miller | 3702396 | 2000-07-11 17:31:38 +1000 | [diff] [blame] | 203 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 204 | .Sh SEE ALSO |
| 205 | .Xr ssh 1 , |
| 206 | .Xr ssh-add 1 , |
| 207 | .Xr ssh-keygen 1 , |
| 208 | .Xr sshd 8 |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 209 | .Sh AUTHORS |
Ben Lindstrom | 035782e | 2001-01-29 08:34:16 +0000 | [diff] [blame] | 210 | OpenSSH is a derivative of the original and free |
| 211 | ssh 1.2.12 release by Tatu Ylonen. |
| 212 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, |
| 213 | Theo de Raadt and Dug Song |
| 214 | removed many bugs, re-added newer features and |
| 215 | created OpenSSH. |
| 216 | Markus Friedl contributed the support for SSH |
| 217 | protocol versions 1.5 and 2.0. |