blob: 00c19921caa4356f40e5c38b89a1fdaf8beb94b5 [file] [log] [blame]
Ben Lindstrom594e2032001-09-12 18:35:30 +00001.\" $OpenBSD: ssh-agent.1,v 1.28 2001/09/05 06:23:07 deraadt Exp $
Damien Miller32aa1441999-10-29 09:15:49 +10002.\"
3.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller32aa1441999-10-29 09:15:49 +10004.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5.\" All rights reserved
6.\"
Damien Millere4340be2000-09-16 13:29:08 +11007.\" 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".
12.\"
Ben Lindstrom92a2e382001-03-05 06:59:27 +000013.\" 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.
Damien Millere4340be2000-09-16 13:29:08 +110016.\"
17.\" Redistribution and use in source and binary forms, with or without
18.\" modification, are permitted provided that the following conditions
19.\" are met:
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.
25.\"
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.
Damien Miller32aa1441999-10-29 09:15:49 +100036.\"
37.Dd September 25, 1999
38.Dt SSH-AGENT 1
39.Os
40.Sh NAME
41.Nm ssh-agent
42.Nd authentication agent
43.Sh SYNOPSIS
Damien Miller22c77262000-04-13 12:26:34 +100044.Nm ssh-agent
Ben Lindstromba1fa1d2001-09-12 17:02:49 +000045.Op Fl c Li | Fl s
46.Op Fl d
47.Op Ar command Op Ar args ...
Ben Lindstrom14920292000-11-21 21:24:55 +000048.Nm ssh-agent
49.Op Fl c Li | Fl s
Ben Lindstrom14920292000-11-21 21:24:55 +000050.Fl k
Damien Miller22c77262000-04-13 12:26:34 +100051.Sh DESCRIPTION
Damien Miller32aa1441999-10-29 09:15:49 +100052.Nm
Damien Millerad833b32000-08-23 10:46:23 +100053is a program to hold private keys used for public key authentication
54(RSA, DSA).
Damien Miller450a7a12000-03-26 13:04:51 +100055The idea is that
Damien Miller32aa1441999-10-29 09:15:49 +100056.Nm
57is started in the beginning of an X-session or a login session, and
58all other windows or programs are started as clients to the ssh-agent
Damien Miller450a7a12000-03-26 13:04:51 +100059program.
60Through use of environment variables the agent can be located
Damien Millerad833b32000-08-23 10:46:23 +100061and automatically used for authentication when logging in to other
Damien Miller32aa1441999-10-29 09:15:49 +100062machines using
63.Xr ssh 1 .
64.Pp
65The options are as follows:
66.Bl -tag -width Ds
67.It Fl c
68Generate C-shell commands on
69.Dv stdout .
70This is the default if
71.Ev SHELL
72looks like it's a csh style of shell.
73.It Fl s
74Generate Bourne shell commands on
75.Dv stdout .
76This is the default if
77.Ev SHELL
78does not look like it's a csh style of shell.
79.It Fl k
80Kill the current agent (given by the
81.Ev SSH_AGENT_PID
82environment variable).
Ben Lindstromd94580c2001-07-04 03:48:02 +000083.It Fl d
84Debug mode. When this option is specified
85.Nm
Ben Lindstroma4a53232001-07-18 15:51:00 +000086will not fork.
Damien Miller32aa1441999-10-29 09:15:49 +100087.El
88.Pp
89If a commandline is given, this is executed as a subprocess of the agent.
90When the command dies, so does the agent.
91.Pp
Damien Miller450a7a12000-03-26 13:04:51 +100092The agent initially does not have any private keys.
93Keys are added using
Damien Miller32aa1441999-10-29 09:15:49 +100094.Xr ssh-add 1 .
Damien Miller22c77262000-04-13 12:26:34 +100095When executed without arguments,
Damien Miller32aa1441999-10-29 09:15:49 +100096.Xr ssh-add 1
Damien Miller22c77262000-04-13 12:26:34 +100097adds the
Damien Miller32aa1441999-10-29 09:15:49 +100098.Pa $HOME/.ssh/identity
Damien Miller450a7a12000-03-26 13:04:51 +100099file.
Damien Miller22c77262000-04-13 12:26:34 +1000100If the identity has a passphrase,
Damien Miller32aa1441999-10-29 09:15:49 +1000101.Xr ssh-add 1
102asks for the passphrase (using a small X11 application if running
Damien Miller450a7a12000-03-26 13:04:51 +1000103under X11, or from the terminal if running without X).
104It then sends the identity to the agent.
105Several identities can be stored in the
Damien Miller32aa1441999-10-29 09:15:49 +1000106agent; the agent can automatically use any of these identities.
107.Ic ssh-add -l
108displays the identities currently held by the agent.
109.Pp
110The idea is that the agent is run in the user's local PC, laptop, or
Damien Miller450a7a12000-03-26 13:04:51 +1000111terminal.
112Authentication data need not be stored on any other
Damien Miller32aa1441999-10-29 09:15:49 +1000113machine, and authentication passphrases never go over the network.
114However, the connection to the agent is forwarded over SSH
115remote logins, and the user can thus use the privileges given by the
116identities anywhere in the network in a secure way.
117.Pp
Damien Miller450a7a12000-03-26 13:04:51 +1000118There are two main ways to get an agent setup:
Ben Lindstrom594e2032001-09-12 18:35:30 +0000119Either the agent starts a new subcommand into which some environment
120variables are exported, or the agent prints the needed shell commands
121(either
Damien Miller32aa1441999-10-29 09:15:49 +1000122.Xr sh 1
123or
124.Xr csh 1
125syntax can be generated) which can be evalled in the calling shell.
126Later
127.Xr ssh 1
Ben Lindstrom0d3e8fa2001-04-04 01:51:25 +0000128looks at these variables and uses them to establish a connection to the agent.
Damien Miller32aa1441999-10-29 09:15:49 +1000129.Pp
130A unix-domain socket is created
131.Pq Pa /tmp/ssh-XXXXXXXX/agent.<pid> ,
132and the name of this socket is stored in the
133.Ev SSH_AUTH_SOCK
134environment
Damien Miller450a7a12000-03-26 13:04:51 +1000135variable.
136The socket is made accessible only to the current user.
Damien Miller32aa1441999-10-29 09:15:49 +1000137This method is easily abused by root or another instance of the same
138user.
139.Pp
140The
141.Ev SSH_AGENT_PID
142environment variable holds the agent's PID.
143.Pp
144The agent exits automatically when the command given on the command
145line terminates.
Damien Miller32aa1441999-10-29 09:15:49 +1000146.Sh FILES
147.Bl -tag -width Ds
148.It Pa $HOME/.ssh/identity
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000149Contains the protocol version 1 RSA authentication identity of the user.
Damien Miller450a7a12000-03-26 13:04:51 +1000150This file should not be readable by anyone but the user.
151It is possible to
Damien Miller32aa1441999-10-29 09:15:49 +1000152specify a passphrase when generating the key; that passphrase will be
Damien Miller450a7a12000-03-26 13:04:51 +1000153used to encrypt the private part of this file.
154This file is not used by
Damien Miller32aa1441999-10-29 09:15:49 +1000155.Nm
156but is normally added to the agent using
157.Xr ssh-add 1
158at login time.
Damien Millerad833b32000-08-23 10:46:23 +1000159.It Pa $HOME/.ssh/id_dsa
Ben Lindstrom18a82ac2001-04-11 15:59:35 +0000160Contains the protocol version 2 DSA authentication identity of the user.
161.It Pa $HOME/.ssh/id_rsa
162Contains the protocol version 2 RSA authentication identity of the user.
Ben Lindstrom14920292000-11-21 21:24:55 +0000163.It Pa /tmp/ssh-XXXXXXXX/agent.<pid>
Damien Miller32aa1441999-10-29 09:15:49 +1000164Unix-domain sockets used to contain the connection to the
Damien Miller450a7a12000-03-26 13:04:51 +1000165authentication agent.
166These sockets should only be readable by the owner.
167The sockets should get automatically removed when the agent exits.
Damien Miller37023962000-07-11 17:31:38 +1000168.El
Damien Miller0bc1bd82000-11-13 22:57:25 +1100169.Sh AUTHORS
Ben Lindstrom035782e2001-01-29 08:34:16 +0000170OpenSSH is a derivative of the original and free
171ssh 1.2.12 release by Tatu Ylonen.
172Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
173Theo de Raadt and Dug Song
174removed many bugs, re-added newer features and
175created OpenSSH.
176Markus Friedl contributed the support for SSH
177protocol versions 1.5 and 2.0.
Damien Miller32aa1441999-10-29 09:15:49 +1000178.Sh SEE ALSO
179.Xr ssh 1 ,
180.Xr ssh-add 1 ,
181.Xr ssh-keygen 1 ,
Ben Lindstrome5b3fb32001-02-10 23:56:35 +0000182.Xr sshd 8