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1 perry 1 ----
2 __NAME__
3
4
5 ssh-agent - authentication agent
6 __SYNOPSIS__
7
8
9 ssh-agent [[-c | -s] [[-d] [[command [[args ...]]
10
11
12 ssh-agent [[-c | -s] -k
13 __DESCRIPTION__
14
15
16 ssh-agent is a program to hold private keys used for public
17 key authentication (RSA, DSA). The idea is that ssh-agent is
18 started in the beginning of an X-session or a login ses-
19 sion, and all other windows or programs are started as
20 clients to the ssh-agent program. Through use of environ-
21 ment variables the agent can be located and automatically
22 used for authentication when logging in to other machines
23 using ssh(1).
24
25
26 The options are as follows:
27 -c Generate C-shell commands on stdout
28 . This is the default if SHELL looks like it's
29 a csh style of shell.
30
31
32 -s
33 Generate Bourne shell commands on stdout. This is the default if SHELL does not look like it's a csh style of shell.
34
35
36 -k
37 Kill the current agent (given by the SSH_AGENT_PID
38 environment variable).
39
40
41 -d
42 Debug mode. When this option is specified ssh-agent will not
43 fork.
44
45
46 If a commandline is given, this is executed as a subprocess
47 of the agent. When the command dies, so does the
48 agent.
49
50
51 The agent initially does not have any private keys. Keys are
52 added using ssh-add(1). When executed without argu-
53 ments, ssh-add(1) adds the
54 $HOME/.ssh/identity file. If the identity has a
55 passphrase, ssh-add(1) asks for the passphrase
56 (using a small X11 application if running under X11, or from
57 the terminal if running without X). It then sends the
58 identity to the agent. Several identities can be stored in
59 the agent; the agent can automatically use any of these
60 identities. ssh-add -l displays the identities cur- rently
61 held by the agent.
62
63
64 The idea is that the agent is run in the user's local PC,
65 laptop, or terminal. Authentication data need not be stored
66 on any other machine, and authentication passphrases never
67 go over the network. However, the connection to the agent is
68 forwarded over SSH remote logins, and the user can thus use
69 the privileges given by the identities anywhere in the
70 network in a secure way.
71
72
73 There are two main ways to get an agent setup: Either the
74 agent starts a new subcommand into which some environment
75 variables are exported, or the agent prints the needed shell
76 commands (either sh(1) or csh(1) syntax
77 can be generated) which can be evalled in the calling shell.
78 Later ssh(1) looks at these variables and uses them
79 to establish a con- nection to the agent.
80
81
82 A unix-domain socket is created
83 (/tmp/ssh-XXXXXXXX/agent.), and the name
84 of this socket is stored in the SSH_AUTH_SOCK
85 environment variable. The socket is made accessible only to
86 the current user. This method is easily abused by root or
87 another instance of the same user.
88
89
90 The SSH_AGENT_PID environment variable holds the
91 agent's PID.
92
93
94 The agent exits automatically when the command given on the
95 command line terminates.
96
97
98 __FILES__
99 $HOME/.ssh/identity
100
101
102 Contains the protocol version 1 RSA authentication identity
103 of the user. This file should not be read- able by anyone
104 but the user. It is possible to spec- ify a passphrase when
105 generating the key; that passphrase will be used to encrypt
106 the private part of this file. This file is not used by
107 ssh-agent but is normally added to the agent using
108 ssh-add(1) at login time.
109
110
111 $HOME/.ssh/id_dsa
112 Contains the protocol version 2 DSA authentication identity
113 of the user.
114
115
116 $HOME/.ssh/id_rsa
117 Contains the protocol version 2 RSA authentication identity
118 of the user.
119
120
121 /tmp/ssh-XXXXXXXX/agent.
122 Unix-domain sockets used to contain the connection to the
123 authentication agent. These sockets should only be readable
124 by the owner. The sockets should get automatically removed
125 when the agent exits.
126
127
128 __AUTHORS__
129
130
131 OpenSSH is a derivative of the original and free ssh 1.2.12
132 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus
133 Friedl, Niels Provos, Theo de Raadt and Dug Song removed
134 many bugs, re-added newer features and created OpenSSH.
135 Markus Friedl contributed the support for SSH protocol ver-
136 sions 1.5 and 2.0.
137 __SEE ALSO__
138
139
140 ssh(1), ssh-add(1),
141 ssh-keygen(1), sshd(8)
142
143
144 BSD September 25, 1999 1
145 ----
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