mirror of git://anongit.mindrot.org/openssh.git
228 lines
6.9 KiB
Groff
228 lines
6.9 KiB
Groff
.\" $OpenBSD: ssh-agent.1,v 1.69 2019/11/30 07:07:59 jmc 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 $Mdocdate: November 30 2019 $
|
|
.Dt SSH-AGENT 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ssh-agent
|
|
.Nd OpenSSH authentication agent
|
|
.Sh SYNOPSIS
|
|
.Nm ssh-agent
|
|
.Op Fl c | s
|
|
.Op Fl \&Dd
|
|
.Op Fl a Ar bind_address
|
|
.Op Fl E Ar fingerprint_hash
|
|
.Op Fl P Ar provider_whitelist
|
|
.Op Fl t Ar life
|
|
.Op Ar command Op Ar arg ...
|
|
.Nm ssh-agent
|
|
.Op Fl c | s
|
|
.Fl k
|
|
.Sh DESCRIPTION
|
|
.Nm
|
|
is a program to hold private keys used for public key authentication.
|
|
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
|
|
.Ux Ns -domain
|
|
socket
|
|
.Ar bind_address .
|
|
The default is
|
|
.Pa $TMPDIR/ssh-XXXXXXXXXX/agent.\*(Ltppid\*(Gt .
|
|
.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 D
|
|
Foreground mode.
|
|
When this option is specified
|
|
.Nm
|
|
will not fork.
|
|
.It Fl d
|
|
Debug mode.
|
|
When this option is specified
|
|
.Nm
|
|
will not fork and will write debug information to standard error.
|
|
.It Fl E Ar fingerprint_hash
|
|
Specifies the hash algorithm used when displaying key fingerprints.
|
|
Valid options are:
|
|
.Dq md5
|
|
and
|
|
.Dq sha256 .
|
|
The default is
|
|
.Dq sha256 .
|
|
.It Fl k
|
|
Kill the current agent (given by the
|
|
.Ev SSH_AGENT_PID
|
|
environment variable).
|
|
.It Fl P Ar provider_whitelist
|
|
Specify a pattern-list of acceptable paths for PKCS#11 and security key shared
|
|
libraries that may be used with the
|
|
.Fl S
|
|
or
|
|
.Fl s
|
|
options to
|
|
.Xr ssh-add 1 .
|
|
Libraries that do not match the whitelist will be refused.
|
|
See PATTERNS in
|
|
.Xr ssh_config 5
|
|
for a description of pattern-list syntax.
|
|
The default whitelist is
|
|
.Dq /usr/lib/*,/usr/local/lib/* .
|
|
.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 t Ar life
|
|
Set a default value for the maximum lifetime of identities added to the agent.
|
|
The lifetime may be specified in seconds or in a time format specified in
|
|
.Xr sshd_config 5 .
|
|
A lifetime specified for an identity with
|
|
.Xr ssh-add 1
|
|
overrides this value.
|
|
Without this option the default maximum lifetime is forever.
|
|
.It Ar command Op Ar arg ...
|
|
If a command (and optional arguments) is given,
|
|
this is executed as a subprocess of the agent.
|
|
The agent exits automatically when the command given on the command
|
|
line terminates.
|
|
.El
|
|
.Pp
|
|
There are two main ways to get an agent set up.
|
|
The first is at the start of an X session,
|
|
where all other windows or programs are started as children of the
|
|
.Nm
|
|
program.
|
|
The agent starts a command under which its environment
|
|
variables are exported, for example
|
|
.Cm ssh-agent xterm & .
|
|
When the command terminates, so does the agent.
|
|
.Pp
|
|
The second method is used for a login session.
|
|
When
|
|
.Nm
|
|
is started,
|
|
it prints the shell commands required to set its environment variables,
|
|
which in turn can be evaluated in the calling shell, for example
|
|
.Cm eval `ssh-agent -s` .
|
|
.Pp
|
|
In both cases,
|
|
.Xr ssh 1
|
|
looks at these environment variables and uses them to establish a connection to the agent.
|
|
.Pp
|
|
The agent initially does not have any private keys.
|
|
Keys are added using
|
|
.Xr ssh-add 1
|
|
or by
|
|
.Xr ssh 1
|
|
when
|
|
.Cm AddKeysToAgent
|
|
is set in
|
|
.Xr ssh_config 5 .
|
|
Multiple identities may be stored in
|
|
.Nm
|
|
concurrently and
|
|
.Xr ssh 1
|
|
will automatically use them if present.
|
|
.Xr ssh-add 1
|
|
is also used to remove keys from
|
|
.Nm
|
|
and to query the keys that are held in one.
|
|
.Pp
|
|
Connections to
|
|
.Nm
|
|
may be forwarded from further remote hosts using the
|
|
.Fl A
|
|
option to
|
|
.Xr ssh 1
|
|
(but see the caveats documented therein),
|
|
avoiding the need for authentication data to be stored on other machines.
|
|
Authentication passphrases and private keys never go over the network:
|
|
the connection to the agent is forwarded over SSH remote connections
|
|
and the result is returned to the requester,
|
|
allowing the user access to their identities anywhere in the network
|
|
in a secure fashion.
|
|
.Sh ENVIRONMENT
|
|
.Bl -tag -width "SSH_AGENT_PID"
|
|
.It Ev SSH_AGENT_PID
|
|
When
|
|
.Nm
|
|
starts, it stores the name of the agent's process ID (PID) in this variable.
|
|
.It Ev SSH_AUTH_SOCK
|
|
When
|
|
.Nm
|
|
starts, it creates a
|
|
.Ux Ns -domain
|
|
socket and stores its pathname in this variable.
|
|
It is accessible only to the current user,
|
|
but is easily abused by root or another instance of the same user.
|
|
.El
|
|
.Sh FILES
|
|
.Bl -tag -width Ds
|
|
.It Pa $TMPDIR/ssh-XXXXXXXXXX/agent.<ppid>
|
|
.Ux Ns -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 SEE ALSO
|
|
.Xr ssh 1 ,
|
|
.Xr ssh-add 1 ,
|
|
.Xr ssh-keygen 1 ,
|
|
.Xr ssh_config 5 ,
|
|
.Xr sshd 8
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
OpenSSH is a derivative of the original and free ssh 1.2.12 release by
|
|
.An Tatu Ylonen .
|
|
.An Aaron Campbell , Bob Beck , Markus Friedl , Niels Provos , Theo de Raadt
|
|
and
|
|
.An Dug Song
|
|
removed many bugs, re-added newer features and created OpenSSH.
|
|
.An Markus Friedl
|
|
contributed the support for SSH protocol versions 1.5 and 2.0.
|