mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-16 10:20:30 +00:00
186 lines
6.3 KiB
Groff
186 lines
6.3 KiB
Groff
.\" $OpenBSD: ssh-agent.1,v 1.33 2002/06/19 00:27:55 deraadt Exp $
|
|
.\"
|
|
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
.\" All rights reserved
|
|
.\"
|
|
.\" As far as I am concerned, the code I have written for this software
|
|
.\" can be used freely for any purpose. Any derived versions of this
|
|
.\" software must be clearly marked as such, and if the derived work is
|
|
.\" incompatible with the protocol description in the RFC file, it must be
|
|
.\" called by a name other than "ssh" or "Secure Shell".
|
|
.\"
|
|
.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
|
|
.\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
|
|
.\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd September 25, 1999
|
|
.Dt SSH-AGENT 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ssh-agent
|
|
.Nd authentication agent
|
|
.Sh SYNOPSIS
|
|
.Nm ssh-agent
|
|
.Op Fl a Ar bind_address
|
|
.Op Fl c Li | Fl s
|
|
.Op Fl d
|
|
.Op Ar command Op Ar args ...
|
|
.Nm ssh-agent
|
|
.Op Fl c Li | Fl s
|
|
.Fl k
|
|
.Sh DESCRIPTION
|
|
.Nm
|
|
is a program to hold private keys used for public key authentication
|
|
(RSA, DSA).
|
|
The idea is that
|
|
.Nm
|
|
is started in the beginning of an X-session or a login session, and
|
|
all other windows or programs are started as clients to the ssh-agent
|
|
program.
|
|
Through use of environment variables the agent can be located
|
|
and automatically used for authentication when logging in to other
|
|
machines using
|
|
.Xr ssh 1 .
|
|
.Pp
|
|
The options are as follows:
|
|
.Bl -tag -width Ds
|
|
.It Fl a Ar bind_address
|
|
Bind the agent to the unix-domain socket
|
|
.Ar bind_address .
|
|
The default is
|
|
.Pa /tmp/ssh-XXXXXXXX/agent.<pid> .
|
|
.It Fl c
|
|
Generate C-shell commands on
|
|
.Dv stdout .
|
|
This is the default if
|
|
.Ev SHELL
|
|
looks like it's a csh style of shell.
|
|
.It Fl s
|
|
Generate Bourne shell commands on
|
|
.Dv stdout .
|
|
This is the default if
|
|
.Ev SHELL
|
|
does not look like it's a csh style of shell.
|
|
.It Fl k
|
|
Kill the current agent (given by the
|
|
.Ev SSH_AGENT_PID
|
|
environment variable).
|
|
.It Fl d
|
|
Debug mode. When this option is specified
|
|
.Nm
|
|
will not fork.
|
|
.El
|
|
.Pp
|
|
If a commandline is given, this is executed as a subprocess of the agent.
|
|
When the command dies, so does the agent.
|
|
.Pp
|
|
The agent initially does not have any private keys.
|
|
Keys are added using
|
|
.Xr ssh-add 1 .
|
|
When executed without arguments,
|
|
.Xr ssh-add 1
|
|
adds the files
|
|
.Pa $HOME/.ssh/id_rsa ,
|
|
.Pa $HOME/.ssh/id_dsa
|
|
and
|
|
.Pa $HOME/.ssh/identity .
|
|
If the identity has a passphrase,
|
|
.Xr ssh-add 1
|
|
asks for the passphrase (using a small X11 application if running
|
|
under X11, or from the terminal if running without X).
|
|
It then sends the identity to the agent.
|
|
Several identities can be stored in the
|
|
agent; the agent can automatically use any of these identities.
|
|
.Ic ssh-add -l
|
|
displays the identities currently held by the agent.
|
|
.Pp
|
|
The idea is that the agent is run in the user's local PC, laptop, or
|
|
terminal.
|
|
Authentication data need not be stored on any other
|
|
machine, and authentication passphrases never go over the network.
|
|
However, the connection to the agent is forwarded over SSH
|
|
remote logins, and the user can thus use the privileges given by the
|
|
identities anywhere in the network in a secure way.
|
|
.Pp
|
|
There are two main ways to get an agent setup:
|
|
Either the agent starts a new subcommand into which some environment
|
|
variables are exported, or the agent prints the needed shell commands
|
|
(either
|
|
.Xr sh 1
|
|
or
|
|
.Xr csh 1
|
|
syntax can be generated) which can be evalled in the calling shell.
|
|
Later
|
|
.Xr ssh 1
|
|
looks at these variables and uses them to establish a connection to the agent.
|
|
.Pp
|
|
The agent will never send a private key over its request channel.
|
|
Instead, operations that require a private key will be performed
|
|
by the agent, and the result will be returned to the requester.
|
|
This way, private keys are not exposed to clients using the agent.
|
|
.Pp
|
|
A unix-domain socket is created
|
|
and the name of this socket is stored in the
|
|
.Ev SSH_AUTH_SOCK
|
|
environment
|
|
variable.
|
|
The socket is made accessible only to the current user.
|
|
This method is easily abused by root or another instance of the same
|
|
user.
|
|
.Pp
|
|
The
|
|
.Ev SSH_AGENT_PID
|
|
environment variable holds the agent's PID.
|
|
.Pp
|
|
The agent exits automatically when the command given on the command
|
|
line terminates.
|
|
.Sh FILES
|
|
.Bl -tag -width Ds
|
|
.It Pa $HOME/.ssh/identity
|
|
Contains the protocol version 1 RSA authentication identity of the user.
|
|
.It Pa $HOME/.ssh/id_dsa
|
|
Contains the protocol version 2 DSA authentication identity of the user.
|
|
.It Pa $HOME/.ssh/id_rsa
|
|
Contains the protocol version 2 RSA authentication identity of the user.
|
|
.It Pa /tmp/ssh-XXXXXXXX/agent.<pid>
|
|
Unix-domain sockets used to contain the connection to the
|
|
authentication agent.
|
|
These sockets should only be readable by the owner.
|
|
The sockets should get automatically removed when the agent exits.
|
|
.El
|
|
.Sh AUTHORS
|
|
OpenSSH is a derivative of the original and free
|
|
ssh 1.2.12 release by Tatu Ylonen.
|
|
Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
|
|
Theo de Raadt and Dug Song
|
|
removed many bugs, re-added newer features and
|
|
created OpenSSH.
|
|
Markus Friedl contributed the support for SSH
|
|
protocol versions 1.5 and 2.0.
|
|
.Sh SEE ALSO
|
|
.Xr ssh 1 ,
|
|
.Xr ssh-add 1 ,
|
|
.Xr ssh-keygen 1 ,
|
|
.Xr sshd 8
|