Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 1 | .\" $OpenBSD: ssh-agent.1,v 1.40 2004/05/13 02:47:50 dtucker 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 | .\" |
| 37 | .Dd September 25, 1999 |
| 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 |
Ben Lindstrom | b7788f3 | 2002-06-06 21:46:08 +0000 | [diff] [blame] | 45 | .Op Fl a Ar bind_address |
Ben Lindstrom | ba1fa1d | 2001-09-12 17:02:49 +0000 | [diff] [blame] | 46 | .Op Fl c Li | Fl s |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 47 | .Op Fl t Ar life |
Ben Lindstrom | ba1fa1d | 2001-09-12 17:02:49 +0000 | [diff] [blame] | 48 | .Op Fl d |
| 49 | .Op Ar command Op Ar args ... |
Ben Lindstrom | 1492029 | 2000-11-21 21:24:55 +0000 | [diff] [blame] | 50 | .Nm ssh-agent |
| 51 | .Op Fl c Li | Fl 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 |
| 56 | (RSA, DSA). |
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 |
| 70 | Bind the agent to the unix-domain socket |
| 71 | .Ar bind_address . |
| 72 | The default is |
Ben Lindstrom | b48057b | 2002-06-25 23:16:31 +0000 | [diff] [blame] | 73 | .Pa /tmp/ssh-XXXXXXXX/agent.<ppid> . |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 74 | .It Fl c |
| 75 | Generate C-shell commands on |
| 76 | .Dv stdout . |
| 77 | This is the default if |
| 78 | .Ev SHELL |
| 79 | looks like it's a csh style of shell. |
| 80 | .It Fl s |
| 81 | Generate Bourne shell commands on |
| 82 | .Dv stdout . |
| 83 | This is the default if |
| 84 | .Ev SHELL |
| 85 | does not look like it's a csh style of shell. |
| 86 | .It Fl k |
| 87 | Kill the current agent (given by the |
| 88 | .Ev SSH_AGENT_PID |
| 89 | environment variable). |
Damien Miller | 53d8148 | 2003-01-22 11:47:19 +1100 | [diff] [blame] | 90 | .It Fl t Ar life |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 91 | 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] | 92 | The lifetime may be specified in seconds or in a time format specified in |
| 93 | .Xr sshd 8 . |
| 94 | A lifetime specified for an identity with |
| 95 | .Xr ssh-add 1 |
| 96 | overrides this value. |
| 97 | Without this option the default maximum lifetime is forever. |
Ben Lindstrom | d94580c | 2001-07-04 03:48:02 +0000 | [diff] [blame] | 98 | .It Fl d |
Damien Miller | 495dca3 | 2003-04-01 21:42:14 +1000 | [diff] [blame] | 99 | Debug mode. |
| 100 | When this option is specified |
Ben Lindstrom | d94580c | 2001-07-04 03:48:02 +0000 | [diff] [blame] | 101 | .Nm |
Ben Lindstrom | a4a5323 | 2001-07-18 15:51:00 +0000 | [diff] [blame] | 102 | will not fork. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 103 | .El |
| 104 | .Pp |
| 105 | If a commandline is given, this is executed as a subprocess of the agent. |
| 106 | When the command dies, so does the agent. |
| 107 | .Pp |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 108 | The agent initially does not have any private keys. |
| 109 | Keys are added using |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 110 | .Xr ssh-add 1 . |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 111 | When executed without arguments, |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 112 | .Xr ssh-add 1 |
Damien Miller | d2b8f16 | 2002-02-05 12:24:19 +1100 | [diff] [blame] | 113 | adds the files |
| 114 | .Pa $HOME/.ssh/id_rsa , |
Ben Lindstrom | cb72e4f | 2002-06-21 00:41:51 +0000 | [diff] [blame] | 115 | .Pa $HOME/.ssh/id_dsa |
Damien Miller | d2b8f16 | 2002-02-05 12:24:19 +1100 | [diff] [blame] | 116 | and |
| 117 | .Pa $HOME/.ssh/identity . |
Damien Miller | 22c7726 | 2000-04-13 12:26:34 +1000 | [diff] [blame] | 118 | If the identity has a passphrase, |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 119 | .Xr ssh-add 1 |
| 120 | asks for the passphrase (using a small X11 application if running |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 121 | under X11, or from the terminal if running without X). |
| 122 | It then sends the identity to the agent. |
| 123 | Several identities can be stored in the |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 124 | agent; the agent can automatically use any of these identities. |
| 125 | .Ic ssh-add -l |
| 126 | displays the identities currently held by the agent. |
| 127 | .Pp |
| 128 | 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] | 129 | terminal. |
| 130 | Authentication data need not be stored on any other |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 131 | machine, and authentication passphrases never go over the network. |
| 132 | However, the connection to the agent is forwarded over SSH |
| 133 | remote logins, and the user can thus use the privileges given by the |
| 134 | identities anywhere in the network in a secure way. |
| 135 | .Pp |
Damien Miller | abbae98 | 2003-05-15 10:16:21 +1000 | [diff] [blame] | 136 | There are two main ways to get an agent set up: |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 137 | The first is that the agent starts a new subcommand into which some environment |
| 138 | variables are exported, eg |
| 139 | .Cm ssh-agent xterm & . |
| 140 | The second is that the agent prints the needed shell commands (either |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 141 | .Xr sh 1 |
| 142 | or |
| 143 | .Xr csh 1 |
Darren Tucker | a86b453 | 2004-05-13 16:45:46 +1000 | [diff] [blame] | 144 | syntax can be generated) which can be evalled in the calling shell, eg |
| 145 | .Cm eval `ssh-agent -s` |
| 146 | for Bourne-type shells such as |
| 147 | .Xr sh 1 |
| 148 | or |
| 149 | .Xr ksh 1 |
| 150 | and |
| 151 | .Cm eval `ssh-agent -c` |
| 152 | for |
| 153 | .Xr csh 1 |
| 154 | and derivatives. |
| 155 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 156 | Later |
| 157 | .Xr ssh 1 |
Ben Lindstrom | 0d3e8fa | 2001-04-04 01:51:25 +0000 | [diff] [blame] | 158 | 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] | 159 | .Pp |
Ben Lindstrom | 11f790b | 2001-12-06 16:37:51 +0000 | [diff] [blame] | 160 | The agent will never send a private key over its request channel. |
| 161 | Instead, operations that require a private key will be performed |
| 162 | by the agent, and the result will be returned to the requester. |
| 163 | This way, private keys are not exposed to clients using the agent. |
| 164 | .Pp |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 165 | A unix-domain socket is created |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 166 | and the name of this socket is stored in the |
| 167 | .Ev SSH_AUTH_SOCK |
| 168 | environment |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 169 | variable. |
| 170 | The socket is made accessible only to the current user. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 171 | This method is easily abused by root or another instance of the same |
| 172 | user. |
| 173 | .Pp |
| 174 | The |
| 175 | .Ev SSH_AGENT_PID |
Ben Lindstrom | 959de99 | 2002-06-23 00:35:25 +0000 | [diff] [blame] | 176 | environment variable holds the agent's process ID. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 177 | .Pp |
| 178 | The agent exits automatically when the command given on the command |
| 179 | line terminates. |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 180 | .Sh FILES |
| 181 | .Bl -tag -width Ds |
| 182 | .It Pa $HOME/.ssh/identity |
Ben Lindstrom | 18a82ac | 2001-04-11 15:59:35 +0000 | [diff] [blame] | 183 | Contains the protocol version 1 RSA authentication identity of the user. |
Damien Miller | ad833b3 | 2000-08-23 10:46:23 +1000 | [diff] [blame] | 184 | .It Pa $HOME/.ssh/id_dsa |
Ben Lindstrom | 18a82ac | 2001-04-11 15:59:35 +0000 | [diff] [blame] | 185 | Contains the protocol version 2 DSA authentication identity of the user. |
| 186 | .It Pa $HOME/.ssh/id_rsa |
| 187 | Contains the protocol version 2 RSA authentication identity of the user. |
Ben Lindstrom | b48057b | 2002-06-25 23:16:31 +0000 | [diff] [blame] | 188 | .It Pa /tmp/ssh-XXXXXXXX/agent.<ppid> |
Damien Miller | 32aa144 | 1999-10-29 09:15:49 +1000 | [diff] [blame] | 189 | Unix-domain sockets used to contain the connection to the |
Damien Miller | 450a7a1 | 2000-03-26 13:04:51 +1000 | [diff] [blame] | 190 | authentication agent. |
| 191 | These sockets should only be readable by the owner. |
| 192 | The sockets should get automatically removed when the agent exits. |
Damien Miller | 3702396 | 2000-07-11 17:31:38 +1000 | [diff] [blame] | 193 | .El |
Damien Miller | f1ce505 | 2003-06-11 22:04:39 +1000 | [diff] [blame] | 194 | .Sh SEE ALSO |
| 195 | .Xr ssh 1 , |
| 196 | .Xr ssh-add 1 , |
| 197 | .Xr ssh-keygen 1 , |
| 198 | .Xr sshd 8 |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 199 | .Sh AUTHORS |
Ben Lindstrom | 035782e | 2001-01-29 08:34:16 +0000 | [diff] [blame] | 200 | OpenSSH is a derivative of the original and free |
| 201 | ssh 1.2.12 release by Tatu Ylonen. |
| 202 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, |
| 203 | Theo de Raadt and Dug Song |
| 204 | removed many bugs, re-added newer features and |
| 205 | created OpenSSH. |
| 206 | Markus Friedl contributed the support for SSH |
| 207 | protocol versions 1.5 and 2.0. |