1 .\" $OpenBSD: ssh-agent.1,v 1.17 2000/11/10 05:10:40 aaron Exp $
3 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 .\" All rights reserved
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".
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.
17 .\" Redistribution and use in source and binary forms, with or without
18 .\" modification, are permitted provided that the following conditions
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.
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.
37 .Dd September 25, 1999
42 .Nd authentication agent
53 is a program to hold private keys used for public key authentication
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
60 Through use of environment variables the agent can be located
61 and automatically used for authentication when logging in to other
65 The options are as follows:
68 Generate C-shell commands on
70 This is the default if
72 looks like it's a csh style of shell.
74 Generate Bourne shell commands on
76 This is the default if
78 does not look like it's a csh style of shell.
80 Kill the current agent (given by the
82 environment variable).
85 If a commandline is given, this is executed as a subprocess of the agent.
86 When the command dies, so does the agent.
88 The agent initially does not have any private keys.
91 When executed without arguments,
94 .Pa $HOME/.ssh/identity
96 If the identity has a passphrase,
98 asks for the passphrase (using a small X11 application if running
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
102 agent; the agent can automatically use any of these identities.
104 displays the identities currently held by the agent.
106 The idea is that the agent is run in the user's local PC, laptop, or
108 Authentication data need not be stored on any other
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.
114 There are two main ways to get an agent setup:
115 Either you let the agent
116 start a new subcommand into which some environment variables are exported, or
117 you let the agent print the needed shell commands (either
121 syntax can be generated) which can be evalled in the calling shell.
124 look at these variables and use them to establish a connection to the agent.
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
132 The socket is made accessible only to the current user.
133 This method is easily abused by root or another instance of the same
138 environment variable holds the agent's PID.
140 The agent exits automatically when the command given on the command
144 .It Pa $HOME/.ssh/identity
145 Contains the RSA authentication identity of the user.
146 This file should not be readable by anyone but the user.
148 specify a passphrase when generating the key; that passphrase will be
149 used to encrypt the private part of this file.
150 This file is not used by
152 but is normally added to the agent using
155 .It Pa $HOME/.ssh/id_dsa
156 Contains the DSA authentication identity of the user.
157 .Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> ,
158 Unix-domain sockets used to contain the connection to the
159 authentication agent.
160 These sockets should only be readable by the owner.
161 The sockets should get automatically removed when the agent exits.
164 Tatu Ylonen <ylo@cs.hut.fi>
167 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
168 removed and newer features re-added.
169 Rapidly after the 1.2.12 release,
170 newer versions bore successively more restrictive licenses.
171 This version of OpenSSH
174 has all components of a restrictive nature (i.e., patents, see
176 directly removed from the source code; any licensed or patented components
180 has been updated to support ssh protocol 1.5.
182 contains added support for
184 authentication and ticket passing.
186 supports one-time password authentication with