1 .\" $OpenBSD: ssh-agent.1,v 1.13 2000/07/06 04:06:56 aaron Exp $
7 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
9 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 .\" All rights reserved
12 .\" Created: Sat Apr 23 20:10:43 1995 ylo
14 .Dd September 25, 1999
19 .Nd authentication agent
30 is a program to hold private keys used for RSA authentication.
33 is started in the beginning of an X-session or a login session, and
34 all other windows or programs are started as clients to the ssh-agent
36 Through use of environment variables the agent can be located
37 and automatically used for RSA authentication when logging in to other
41 The options are as follows:
44 Generate C-shell commands on
46 This is the default if
48 looks like it's a csh style of shell.
50 Generate Bourne shell commands on
52 This is the default if
54 does not look like it's a csh style of shell.
56 Kill the current agent (given by the
58 environment variable).
61 If a commandline is given, this is executed as a subprocess of the agent.
62 When the command dies, so does the agent.
64 The agent initially does not have any private keys.
67 When executed without arguments,
70 .Pa $HOME/.ssh/identity
72 If the identity has a passphrase,
74 asks for the passphrase (using a small X11 application if running
75 under X11, or from the terminal if running without X).
76 It then sends the identity to the agent.
77 Several identities can be stored in the
78 agent; the agent can automatically use any of these identities.
80 displays the identities currently held by the agent.
82 The idea is that the agent is run in the user's local PC, laptop, or
84 Authentication data need not be stored on any other
85 machine, and authentication passphrases never go over the network.
86 However, the connection to the agent is forwarded over SSH
87 remote logins, and the user can thus use the privileges given by the
88 identities anywhere in the network in a secure way.
90 There are two main ways to get an agent setup:
91 Either you let the agent
92 start a new subcommand into which some environment variables are exported, or
93 you let the agent print the needed shell commands (either
97 syntax can be generated) which can be evalled in the calling shell.
100 look at these variables and use them to establish a connection to the agent.
102 A unix-domain socket is created
103 .Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> ,
104 and the name of this socket is stored in the
108 The socket is made accessible only to the current user.
109 This method is easily abused by root or another instance of the same
114 environment variable holds the agent's PID.
116 The agent exits automatically when the command given on the command
120 .It Pa $HOME/.ssh/identity
121 Contains the RSA authentication identity of the user.
122 This file should not be readable by anyone but the user.
124 specify a passphrase when generating the key; that passphrase will be
125 used to encrypt the private part of this file.
126 This file is not used by
128 but is normally added to the agent using
131 .It Pa /tmp/ssh-XXXX/agent.<pid> ,
132 Unix-domain sockets used to contain the connection to the
133 authentication agent.
134 These sockets should only be readable by the owner.
135 The sockets should get automatically removed when the agent exits.
138 Tatu Ylonen <ylo@cs.hut.fi>
141 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
142 removed and newer features re-added.
143 Rapidly after the 1.2.12 release,
144 newer versions bore successively more restrictive licenses.
145 This version of OpenSSH
148 has all components of a restrictive nature (i.e., patents)
149 directly removed from the source code; any licensed or patented components
153 has been updated to support ssh protocol 1.5.
155 contains added support for
157 authentication and ticket passing.
159 supports one-time password authentication with