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author | Colin Watson <cjwatson@debian.org> | 2010-08-23 22:50:14 +0100 |
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committer | Colin Watson <cjwatson@debian.org> | 2010-08-23 22:50:14 +0100 |
commit | 43094ebf14c9b16f1ea398bc5b65a7335e947288 (patch) | |
tree | 10f5da5fe4f61992d238da7a71692157a609c819 /ssh-agent.0 | |
parent | 4b8ebe7e3647d3078fd4d025f4325b8cc1ac20d6 (diff) | |
parent | ff0095389ba9a9e4599e6051c8d5bae6777c4d64 (diff) |
Import 5.6p1 tarball
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-rw-r--r-- | ssh-agent.0 | 118 |
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1 | SSH-AGENT(1) OpenBSD Reference Manual SSH-AGENT(1) | ||
2 | |||
3 | NAME | ||
4 | ssh-agent - authentication agent | ||
5 | |||
6 | SYNOPSIS | ||
7 | ssh-agent [-c | -s] [-d] [-a bind_address] [-t life] [command [arg ...]] | ||
8 | ssh-agent [-c | -s] -k | ||
9 | |||
10 | DESCRIPTION | ||
11 | ssh-agent is a program to hold private keys used for public key | ||
12 | authentication (RSA, DSA). The idea is that ssh-agent is started in the | ||
13 | beginning of an X-session or a login session, and all other windows or | ||
14 | programs are started as clients to the ssh-agent program. Through use of | ||
15 | environment variables the agent can be located and automatically used for | ||
16 | authentication when logging in to other machines using ssh(1). | ||
17 | |||
18 | The options are as follows: | ||
19 | |||
20 | -a bind_address | ||
21 | Bind the agent to the UNIX-domain socket bind_address. The | ||
22 | default is /tmp/ssh-XXXXXXXXXX/agent.<ppid>. | ||
23 | |||
24 | -c Generate C-shell commands on stdout. This is the default if | ||
25 | SHELL looks like it's a csh style of shell. | ||
26 | |||
27 | -d Debug mode. When this option is specified ssh-agent will not | ||
28 | fork. | ||
29 | |||
30 | -k Kill the current agent (given by the SSH_AGENT_PID environment | ||
31 | variable). | ||
32 | |||
33 | -s Generate Bourne shell commands on stdout. This is the default if | ||
34 | SHELL does not look like it's a csh style of shell. | ||
35 | |||
36 | -t life | ||
37 | Set a default value for the maximum lifetime of identities added | ||
38 | to the agent. The lifetime may be specified in seconds or in a | ||
39 | time format specified in sshd_config(5). A lifetime specified | ||
40 | for an identity with ssh-add(1) overrides this value. Without | ||
41 | this option the default maximum lifetime is forever. | ||
42 | |||
43 | If a commandline is given, this is executed as a subprocess of the agent. | ||
44 | When the command dies, so does the agent. | ||
45 | |||
46 | The agent initially does not have any private keys. Keys are added using | ||
47 | ssh-add(1). When executed without arguments, ssh-add(1) adds the files | ||
48 | ~/.ssh/id_rsa, ~/.ssh/id_dsa and ~/.ssh/identity. If the identity has a | ||
49 | passphrase, ssh-add(1) asks for the passphrase on the terminal if it has | ||
50 | one or from a small X11 program if running under X11. If neither of | ||
51 | these is the case then the authentication will fail. It then sends the | ||
52 | identity to the agent. Several identities can be stored in the agent; | ||
53 | the agent can automatically use any of these identities. ssh-add -l | ||
54 | displays the identities currently held by the agent. | ||
55 | |||
56 | The idea is that the agent is run in the user's local PC, laptop, or | ||
57 | terminal. Authentication data need not be stored on any other machine, | ||
58 | and authentication passphrases never go over the network. However, the | ||
59 | connection to the agent is forwarded over SSH remote logins, and the user | ||
60 | can thus use the privileges given by the identities anywhere in the | ||
61 | network in a secure way. | ||
62 | |||
63 | There are two main ways to get an agent set up: The first is that the | ||
64 | agent starts a new subcommand into which some environment variables are | ||
65 | exported, eg ssh-agent xterm &. The second is that the agent prints the | ||
66 | needed shell commands (either sh(1) or csh(1) syntax can be generated) | ||
67 | which can be evaluated in the calling shell, eg eval `ssh-agent -s` for | ||
68 | Bourne-type shells such as sh(1) or ksh(1) and eval `ssh-agent -c` for | ||
69 | csh(1) and derivatives. | ||
70 | |||
71 | Later ssh(1) looks at these variables and uses them to establish a | ||
72 | connection to the agent. | ||
73 | |||
74 | The agent will never send a private key over its request channel. | ||
75 | Instead, operations that require a private key will be performed by the | ||
76 | agent, and the result will be returned to the requester. This way, | ||
77 | private keys are not exposed to clients using the agent. | ||
78 | |||
79 | A UNIX-domain socket is created and the name of this socket is stored in | ||
80 | the SSH_AUTH_SOCK environment variable. The socket is made accessible | ||
81 | only to the current user. This method is easily abused by root or | ||
82 | another instance of the same user. | ||
83 | |||
84 | The SSH_AGENT_PID environment variable holds the agent's process ID. | ||
85 | |||
86 | The agent exits automatically when the command given on the command line | ||
87 | terminates. | ||
88 | |||
89 | FILES | ||
90 | ~/.ssh/identity | ||
91 | Contains the protocol version 1 RSA authentication identity of | ||
92 | the user. | ||
93 | |||
94 | ~/.ssh/id_dsa | ||
95 | Contains the protocol version 2 DSA authentication identity of | ||
96 | the user. | ||
97 | |||
98 | ~/.ssh/id_rsa | ||
99 | Contains the protocol version 2 RSA authentication identity of | ||
100 | the user. | ||
101 | |||
102 | /tmp/ssh-XXXXXXXXXX/agent.<ppid> | ||
103 | UNIX-domain sockets used to contain the connection to the | ||
104 | authentication agent. These sockets should only be readable by | ||
105 | the owner. The sockets should get automatically removed when the | ||
106 | agent exits. | ||
107 | |||
108 | SEE ALSO | ||
109 | ssh(1), ssh-add(1), ssh-keygen(1), sshd(8) | ||
110 | |||
111 | AUTHORS | ||
112 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
113 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
114 | de Raadt and Dug Song removed many bugs, re-added newer features and | ||
115 | created OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
116 | versions 1.5 and 2.0. | ||
117 | |||
118 | OpenBSD 4.8 January 17, 2010 OpenBSD 4.8 | ||