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c0ecc314 | 1 | .\" $OpenBSD: ssh-agent.1,v 1.24 2001/04/10 09:13:21 itojun Exp $ |
bf740959 | 2 | .\" |
3 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
bf740959 | 4 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
5 | .\" All rights reserved | |
6 | .\" | |
bcbf86ec | 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 | .\" | |
f3c7c613 | 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. | |
bcbf86ec | 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. | |
bf740959 | 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 | |
f54651ce | 44 | .Nm ssh-agent |
bf740959 | 45 | .Ar command |
d343d900 | 46 | .Ar args ... |
47 | .Nm ssh-agent | |
48 | .Op Fl c Li | Fl s | |
49 | .Nm ssh-agent | |
50 | .Fl k | |
f54651ce | 51 | .Sh DESCRIPTION |
bf740959 | 52 | .Nm |
2e73a022 | 53 | is a program to hold private keys used for public key authentication |
54 | (RSA, DSA). | |
4fe2af09 | 55 | The idea is that |
bf740959 | 56 | .Nm |
57 | is started in the beginning of an X-session or a login session, and | |
58 | all other windows or programs are started as clients to the ssh-agent | |
4fe2af09 | 59 | program. |
60 | Through use of environment variables the agent can be located | |
2e73a022 | 61 | and automatically used for authentication when logging in to other |
bf740959 | 62 | machines using |
63 | .Xr ssh 1 . | |
64 | .Pp | |
65 | The options are as follows: | |
66 | .Bl -tag -width Ds | |
67 | .It Fl c | |
68 | Generate C-shell commands on | |
69 | .Dv stdout . | |
70 | This is the default if | |
71 | .Ev SHELL | |
72 | looks like it's a csh style of shell. | |
73 | .It Fl s | |
74 | Generate Bourne shell commands on | |
75 | .Dv stdout . | |
76 | This is the default if | |
77 | .Ev SHELL | |
78 | does not look like it's a csh style of shell. | |
79 | .It Fl k | |
80 | Kill the current agent (given by the | |
81 | .Ev SSH_AGENT_PID | |
82 | environment variable). | |
83 | .El | |
84 | .Pp | |
85 | If a commandline is given, this is executed as a subprocess of the agent. | |
86 | When the command dies, so does the agent. | |
87 | .Pp | |
4fe2af09 | 88 | The agent initially does not have any private keys. |
89 | Keys are added using | |
bf740959 | 90 | .Xr ssh-add 1 . |
f54651ce | 91 | When executed without arguments, |
bf740959 | 92 | .Xr ssh-add 1 |
f54651ce | 93 | adds the |
bf740959 | 94 | .Pa $HOME/.ssh/identity |
4fe2af09 | 95 | file. |
f54651ce | 96 | If the identity has a passphrase, |
bf740959 | 97 | .Xr ssh-add 1 |
98 | asks for the passphrase (using a small X11 application if running | |
4fe2af09 | 99 | under X11, or from the terminal if running without X). |
100 | It then sends the identity to the agent. | |
101 | Several identities can be stored in the | |
bf740959 | 102 | agent; the agent can automatically use any of these identities. |
103 | .Ic ssh-add -l | |
104 | displays the identities currently held by the agent. | |
105 | .Pp | |
106 | The idea is that the agent is run in the user's local PC, laptop, or | |
4fe2af09 | 107 | terminal. |
108 | Authentication data need not be stored on any other | |
bf740959 | 109 | machine, and authentication passphrases never go over the network. |
110 | However, the connection to the agent is forwarded over SSH | |
111 | remote logins, and the user can thus use the privileges given by the | |
112 | identities anywhere in the network in a secure way. | |
113 | .Pp | |
4fe2af09 | 114 | There are two main ways to get an agent setup: |
115 | Either you let the agent | |
bf740959 | 116 | start a new subcommand into which some environment variables are exported, or |
117 | you let the agent print the needed shell commands (either | |
118 | .Xr sh 1 | |
119 | or | |
120 | .Xr csh 1 | |
121 | syntax can be generated) which can be evalled in the calling shell. | |
122 | Later | |
123 | .Xr ssh 1 | |
9d451c5a | 124 | looks at these variables and uses them to establish a connection to the agent. |
bf740959 | 125 | .Pp |
126 | A unix-domain socket is created | |
127 | .Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> , | |
128 | and the name of this socket is stored in the | |
129 | .Ev SSH_AUTH_SOCK | |
130 | environment | |
4fe2af09 | 131 | variable. |
132 | The socket is made accessible only to the current user. | |
bf740959 | 133 | This method is easily abused by root or another instance of the same |
134 | user. | |
135 | .Pp | |
136 | The | |
137 | .Ev SSH_AGENT_PID | |
138 | environment variable holds the agent's PID. | |
139 | .Pp | |
140 | The agent exits automatically when the command given on the command | |
141 | line terminates. | |
142 | .Sh FILES | |
143 | .Bl -tag -width Ds | |
144 | .It Pa $HOME/.ssh/identity | |
c0ecc314 | 145 | Contains the protocol version 1 RSA authentication identity of the user. |
4fe2af09 | 146 | This file should not be readable by anyone but the user. |
147 | It is possible to | |
bf740959 | 148 | specify a passphrase when generating the key; that passphrase will be |
4fe2af09 | 149 | used to encrypt the private part of this file. |
150 | This file is not used by | |
bf740959 | 151 | .Nm |
152 | but is normally added to the agent using | |
153 | .Xr ssh-add 1 | |
154 | at login time. | |
2e73a022 | 155 | .It Pa $HOME/.ssh/id_dsa |
c0ecc314 | 156 | Contains the protocol version 2 DSA authentication identity of the user. |
157 | .It Pa $HOME/.ssh/id_rsa | |
158 | Contains the protocol version 2 RSA authentication identity of the user. | |
d343d900 | 159 | .It Pa /tmp/ssh-XXXXXXXX/agent.<pid> |
bf740959 | 160 | Unix-domain sockets used to contain the connection to the |
4fe2af09 | 161 | authentication agent. |
162 | These sockets should only be readable by the owner. | |
163 | The sockets should get automatically removed when the agent exits. | |
089fbbd2 | 164 | .El |
fa08c86b | 165 | .Sh AUTHORS |
5fb622e4 | 166 | OpenSSH is a derivative of the original and free |
167 | ssh 1.2.12 release by Tatu Ylonen. | |
168 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
169 | Theo de Raadt and Dug Song | |
170 | removed many bugs, re-added newer features and | |
171 | created OpenSSH. | |
172 | Markus Friedl contributed the support for SSH | |
173 | protocol versions 1.5 and 2.0. | |
bf740959 | 174 | .Sh SEE ALSO |
175 | .Xr ssh 1 , | |
176 | .Xr ssh-add 1 , | |
177 | .Xr ssh-keygen 1 , | |
f98d56f0 | 178 | .Xr sshd 8 |