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SSH-AGENT(1)		FreeBSD	General	Commands Manual		  SSH-AGENT(1)

NAME
     ssh-agent -- authentication agent

SYNOPSIS
     ssh-agent [-c | -s] [-dx] [-a bind_address] [-t life] [command [arg ...]]
     ssh-agent [-c | -s] -k

DESCRIPTION
     ssh-agent is a program to hold private keys used for public key authenti-
     cation (RSA, DSA, ECDSA).	The idea is that ssh-agent 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 ssh(1).

     The options are as	follows:

     -a	bind_address
	     Bind the agent to the UNIX-domain socket bind_address.  The
	     default is	$TMPDIR/ssh-XXXXXXXXXX/agent._ppid_.

     -c	     Generate C-shell commands on stdout.  This	is the default if
	     SHELL looks like it's a csh style of shell.

     -d	     Debug mode.  When this option is specified	ssh-agent will not
	     fork.

     -k	     Kill the current agent (given by the SSH_AGENT_PID	environment
	     variable).

     -s	     Generate Bourne shell commands on stdout.	This is	the default if
	     SHELL does	not look like it's a csh style of shell.

     -t	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 sshd_config(5).  A lifetime specified
	     for an identity with ssh-add(1) overrides this value.  Without
	     this option the default maximum lifetime is forever.

     -x	     Exit after	the last client	has disconnected.

     If	a commandline is given,	this is	executed as a subprocess of the	agent.
     When the command dies, so does the	agent.

     The agent initially does not have any private keys.  Keys are added using
     ssh-add(1).  When executed	without	arguments, ssh-add(1) adds the files
     ~/.ssh/id_rsa, ~/.ssh/id_dsa, ~/.ssh/id_ecdsa and ~/.ssh/identity.	 If
     the identity has a	passphrase, ssh-add(1) asks for	the passphrase on the
     terminal if it has	one or from a small X11	program	if running under X11.
     If	neither	of these is the	case then the authentication will fail.	 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.
     ssh-add -l	displays the identities	currently held by the agent.

     The idea is that the agent	is run in the user's local PC, laptop, or ter-
     minal.  Authentication data need not be stored on any other machine, and
     authentication passphrases	never go over the network.  However, the con-
     nection to	the agent is forwarded over SSH	remote logins, and the user
     can thus use the privileges given by the identities anywhere in the net-
     work in a secure way.

     There are two main	ways to	get an agent set up: The first is that the
     agent starts a new	subcommand into	which some environment variables are
     exported, eg ssh-agent xterm &.  The second is that the agent prints the
     needed shell commands (either sh(1) or csh(1) syntax can be generated)
     which can be evaluated in the calling shell, eg eval `ssh-agent -s` for
     Bourne-type shells	such as	sh(1) or ksh(1)	and eval `ssh-agent -c`	for
     csh(1) and	derivatives.

     Later ssh(1) looks	at these variables and uses them to establish a	con-
     nection to	the agent.

     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, pri-
     vate keys are not exposed to clients using	the agent.

     A UNIX-domain socket is created and the name of this socket is stored in
     the 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.

     The SSH_AGENT_PID environment variable holds the agent's process ID.

     The agent exits automatically when	the command given on the command line
     terminates.

FILES
     ~/.ssh/identity
	     Contains the protocol version 1 RSA authentication	identity of
	     the user.

     ~/.ssh/id_dsa
	     Contains the protocol version 2 DSA authentication	identity of
	     the user.

     ~/.ssh/id_ecdsa
	     Contains the protocol version 2 ECDSA authentication identity of
	     the user.

     ~/.ssh/id_rsa
	     Contains the protocol version 2 RSA authentication	identity of
	     the user.

     $TMPDIR/ssh-XXXXXXXXXX/agent.<ppid>
	     UNIX-domain sockets used to contain the connection	to the authen-
	     tication agent.  These sockets should only	be readable by the
	     owner.  The sockets should	get automatically removed when the
	     agent exits.

SEE ALSO
     ssh(1), ssh-add(1), ssh-keygen(1),	sshd(8)

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 cre-
     ated OpenSSH.  Markus Friedl contributed the support for SSH protocol
     versions 1.5 and 2.0.

FreeBSD	9.3		       November	21, 2010		   FreeBSD 9.3

NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | AUTHORS

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