1 .\" $OpenBSD: ssh-agent.1,v 1.14 2000/08/19 21:34:43 markus 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 public key authentication
34 is started in the beginning of an X-session or a login session, and
35 all other windows or programs are started as clients to the ssh-agent
37 Through use of environment variables the agent can be located
38 and automatically used for authentication when logging in to other
42 The options are as follows:
45 Generate C-shell commands on
47 This is the default if
49 looks like it's a csh style of shell.
51 Generate Bourne shell commands on
53 This is the default if
55 does not look like it's a csh style of shell.
57 Kill the current agent (given by the
59 environment variable).
62 If a commandline is given, this is executed as a subprocess of the agent.
63 When the command dies, so does the agent.
65 The agent initially does not have any private keys.
68 When executed without arguments,
71 .Pa $HOME/.ssh/identity
73 If the identity has a passphrase,
75 asks for the passphrase (using a small X11 application if running
76 under X11, or from the terminal if running without X).
77 It then sends the identity to the agent.
78 Several identities can be stored in the
79 agent; the agent can automatically use any of these identities.
81 displays the identities currently held by the agent.
83 The idea is that the agent is run in the user's local PC, laptop, or
85 Authentication data need not be stored on any other
86 machine, and authentication passphrases never go over the network.
87 However, the connection to the agent is forwarded over SSH
88 remote logins, and the user can thus use the privileges given by the
89 identities anywhere in the network in a secure way.
91 There are two main ways to get an agent setup:
92 Either you let the agent
93 start a new subcommand into which some environment variables are exported, or
94 you let the agent print the needed shell commands (either
98 syntax can be generated) which can be evalled in the calling shell.
101 look at these variables and use them to establish a connection to the agent.
103 A unix-domain socket is created
104 .Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> ,
105 and the name of this socket is stored in the
109 The socket is made accessible only to the current user.
110 This method is easily abused by root or another instance of the same
115 environment variable holds the agent's PID.
117 The agent exits automatically when the command given on the command
121 .It Pa $HOME/.ssh/identity
122 Contains the RSA authentication identity of the user.
123 This file should not be readable by anyone but the user.
125 specify a passphrase when generating the key; that passphrase will be
126 used to encrypt the private part of this file.
127 This file is not used by
129 but is normally added to the agent using
132 .It Pa $HOME/.ssh/id_dsa
133 Contains the DSA authentication identity of the user.
134 .Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> ,
135 Unix-domain sockets used to contain the connection to the
136 authentication agent.
137 These sockets should only be readable by the owner.
138 The sockets should get automatically removed when the agent exits.
141 Tatu Ylonen <ylo@cs.hut.fi>
144 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
145 removed and newer features re-added.
146 Rapidly after the 1.2.12 release,
147 newer versions bore successively more restrictive licenses.
148 This version of OpenSSH
151 has all components of a restrictive nature (i.e., patents)
152 directly removed from the source code; any licensed or patented components
156 has been updated to support ssh protocol 1.5.
158 contains added support for
160 authentication and ticket passing.
162 supports one-time password authentication with