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SSH_CONFIG(5)		  FreeBSD File Formats Manual		 SSH_CONFIG(5)

NAME
     ssh_config	-- OpenSSH SSH client configuration files

SYNOPSIS
     ~/.ssh/config
     /etc/ssh/ssh_config

DESCRIPTION
     ssh(1) obtains configuration data from the	following sources in the fol-
     lowing order:

	   1.	command-line options
	   2.	user's configuration file (~/.ssh/config)
	   3.	system-wide configuration file (/etc/ssh/ssh_config)

     For each parameter, the first obtained value will be used.	 The configu-
     ration files contain sections separated by	``Host'' specifications, and
     that section is only applied for hosts that match one of the patterns
     given in the specification.  The matched host name	is the one given on
     the command line.

     Since the first obtained value for	each parameter is used,	more host-spe-
     cific declarations	should be given	near the beginning of the file,	and
     general defaults at the end.

     The configuration file has	the following format:

     Empty lines and lines starting with `#' are comments.  Otherwise a	line
     is	of the format ``keyword	arguments''.  Configuration options may	be
     separated by whitespace or	optional whitespace and	exactly	one `='; the
     latter format is useful to	avoid the need to quote	whitespace when	speci-
     fying configuration options using the ssh,	scp, and sftp -o option.
     Arguments may optionally be enclosed in double quotes (") in order	to
     represent arguments containing spaces.

     The possible keywords and their meanings are as follows (note that	key-
     words are case-insensitive	and arguments are case-sensitive):

     Host    Restricts the following declarations (up to the next Host key-
	     word) to be only for those	hosts that match one of	the patterns
	     given after the keyword.  If more than one	pattern	is provided,
	     they should be separated by whitespace.  A	single `*' as a	pat-
	     tern can be used to provide global	defaults for all hosts.	 The
	     host is the hostname argument given on the	command	line (i.e. the
	     name is not converted to a	canonicalized host name	before match-
	     ing).

	     A pattern entry may be negated by prefixing it with an exclama-
	     tion mark (`!').  If a negated entry is matched, then the Host
	     entry is ignored, regardless of whether any other patterns	on the
	     line match.  Negated matches are therefore	useful to provide
	     exceptions	for wildcard matches.

	     See PATTERNS for more information on patterns.

     AddressFamily
	     Specifies which address family to use when	connecting.  Valid
	     arguments are ``any'', ``inet'' (use IPv4 only), or ``inet6''
	     (use IPv6 only).

     BatchMode
	     If	set to ``yes'',	passphrase/password querying will be disabled.
	     This option is useful in scripts and other	batch jobs where no
	     user is present to	supply the password.  The argument must	be
	     ``yes'' or	``no''.	 The default is	``no''.

     BindAddress
	     Use the specified address on the local machine as the source
	     address of	the connection.	 Only useful on	systems	with more than
	     one address.  Note	that this option does not work if
	     UsePrivilegedPort is set to ``yes''.

     ChallengeResponseAuthentication
	     Specifies whether to use challenge-response authentication.  The
	     argument to this keyword must be ``yes'' or ``no''.  The default
	     is	``yes''.

     CheckHostIP
	     If	this flag is set to ``yes'', ssh(1) will additionally check
	     the host IP address in the	known_hosts file.  This	allows ssh to
	     detect if a host key changed due to DNS spoofing.	If the option
	     is	set to ``no'', the check will not be executed.	The default is
	     ``no''.

     Cipher  Specifies the cipher to use for encrypting	the session in proto-
	     col version 1.  Currently,	``blowfish'', ``3des'',	and ``des''
	     are supported.  des is only supported in the ssh(1) client	for
	     interoperability with legacy protocol 1 implementations that do
	     not support the 3des cipher.  Its use is strongly discouraged due
	     to	cryptographic weaknesses.  The default is ``3des''.

     Ciphers
	     Specifies the ciphers allowed for protocol	version	2 in order of
	     preference.  Multiple ciphers must	be comma-separated.  The sup-
	     ported ciphers are	``3des-cbc'', ``aes128-cbc'', ``aes192-cbc'',
	     ``aes256-cbc'', ``aes128-ctr'', ``aes192-ctr'', ``aes256-ctr'',
	     ``aes128-gcm@openssh.com'', ``aes256-gcm@openssh.com'',
	     ``arcfour128'', ``arcfour256'', ``arcfour'', ``blowfish-cbc'',
	     and ``cast128-cbc''.  The default is:

		aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
		aes128-gcm@openssh.com,aes256-gcm@openssh.com,
		aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
		aes256-cbc,arcfour

     ClearAllForwardings
	     Specifies that all	local, remote, and dynamic port	forwardings
	     specified in the configuration files or on	the command line be
	     cleared.  This option is primarily	useful when used from the
	     ssh(1) command line to clear port forwardings set in configura-
	     tion files, and is	automatically set by scp(1) and	sftp(1).  The
	     argument must be ``yes'' or ``no''.  The default is ``no''.

     Compression
	     Specifies whether to use compression.  The	argument must be
	     ``yes'' or	``no''.	 The default is	``no''.

     CompressionLevel
	     Specifies the compression level to	use if compression is enabled.
	     The argument must be an integer from 1 (fast) to 9	(slow, best).
	     The default level is 6, which is good for most applications.  The
	     meaning of	the values is the same as in gzip(1).  Note that this
	     option applies to protocol	version	1 only.

     ConnectionAttempts
	     Specifies the number of tries (one	per second) to make before
	     exiting.  The argument must be an integer.	 This may be useful in
	     scripts if	the connection sometimes fails.	 The default is	1.

     ConnectTimeout
	     Specifies the timeout (in seconds)	used when connecting to	the
	     SSH server, instead of using the default system TCP timeout.
	     This value	is used	only when the target is	down or	really
	     unreachable, not when it refuses the connection.

     ControlMaster
	     Enables the sharing of multiple sessions over a single network
	     connection.  When set to ``yes'', ssh(1) will listen for connec-
	     tions on a	control	socket specified using the ControlPath argu-
	     ment.  Additional sessions	can connect to this socket using the
	     same ControlPath with ControlMaster set to	``no'' (the default).
	     These sessions will try to	reuse the master instance's network
	     connection	rather than initiating new ones, but will fall back to
	     connecting	normally if the	control	socket does not	exist, or is
	     not listening.

	     Setting this to ``ask'' will cause	ssh to listen for control con-
	     nections, but require confirmation	using the SSH_ASKPASS program
	     before they are accepted (see ssh-add(1) for details).  If	the
	     ControlPath cannot	be opened, ssh will continue without connect-
	     ing to a master instance.

	     X11 and ssh-agent(1) forwarding is	supported over these multi-
	     plexed connections, however the display and agent forwarded will
	     be	the one	belonging to the master	connection i.e.	it is not pos-
	     sible to forward multiple displays	or agents.

	     Two additional options allow for opportunistic multiplexing: try
	     to	use a master connection	but fall back to creating a new	one if
	     one does not already exist.  These	options	are: ``auto'' and
	     ``autoask''.  The latter requires confirmation like the ``ask''
	     option.

     ControlPath
	     Specify the path to the control socket used for connection	shar-
	     ing as described in the ControlMaster section above or the	string
	     ``none'' to disable connection sharing.  In the path, `%L'	will
	     be	substituted by the first component of the local	host name,
	     `%l' will be substituted by the local host	name (including	any
	     domain name), `%h'	will be	substituted by the target host name,
	     `%n' will be substituted by the original target host name speci-
	     fied on the command line, `%p' the	port, `%r' by the remote login
	     username, and `%u'	by the username	of the user running ssh(1).
	     It	is recommended that any	ControlPath used for opportunistic
	     connection	sharing	include	at least %h, %p, and %r.  This ensures
	     that shared connections are uniquely identified.

     ControlPersist
	     When used in conjunction with ControlMaster, specifies that the
	     master connection should remain open in the background (waiting
	     for future	client connections) after the initial client connec-
	     tion has been closed.  If set to ``no'', then the master connec-
	     tion will not be placed into the background, and will close as
	     soon as the initial client	connection is closed.  If set to
	     ``yes'', then the master connection will remain in	the background
	     indefinitely (until killed	or closed via a	mechanism such as the
	     ssh(1) ``-O exit''	option).  If set to a time in seconds, or a
	     time in any of the	formats	documented in sshd_config(5), then the
	     backgrounded master connection will automatically terminate after
	     it	has remained idle (with	no client connections) for the speci-
	     fied time.

     DynamicForward
	     Specifies that a TCP port on the local machine be forwarded over
	     the secure	channel, and the application protocol is then used to
	     determine where to	connect	to from	the remote machine.

	     The argument must be [bind_address:]port.	IPv6 addresses can be
	     specified by enclosing addresses in square	brackets.  By default,
	     the local port is bound in	accordance with	the GatewayPorts set-
	     ting.  However, an	explicit bind_address may be used to bind the
	     connection	to a specific address.	The bind_address of
	     ``localhost'' indicates that the listening	port be	bound for
	     local use only, while an empty address or `*' indicates that the
	     port should be available from all interfaces.

	     Currently the SOCKS4 and SOCKS5 protocols are supported, and
	     ssh(1) will act as	a SOCKS	server.	 Multiple forwardings may be
	     specified,	and additional forwardings can be given	on the command
	     line.  Only the superuser can forward privileged ports.

     EnableSSHKeysign
	     Setting this option to ``yes'' in the global client configuration
	     file /etc/ssh/ssh_config enables the use of the helper program
	     ssh-keysign(8) during HostbasedAuthentication.  The argument must
	     be	``yes''	or ``no''.  The	default	is ``no''.  This option	should
	     be	placed in the non-hostspecific section.	 See ssh-keysign(8)
	     for more information.

     EscapeChar
	     Sets the escape character (default: `~').	The escape character
	     can also be set on	the command line.  The argument	should be a
	     single character, `^' followed by a letter, or ``none'' to	dis-
	     able the escape character entirely	(making	the connection trans-
	     parent for	binary data).

     ExitOnForwardFailure
	     Specifies whether ssh(1) should terminate the connection if it
	     cannot set	up all requested dynamic, tunnel, local, and remote
	     port forwardings.	The argument must be ``yes'' or	``no''.	 The
	     default is	``no''.

     ForwardAgent
	     Specifies whether the connection to the authentication agent (if
	     any) will be forwarded to the remote machine.  The	argument must
	     be	``yes''	or ``no''.  The	default	is ``no''.

	     Agent forwarding should be	enabled	with caution.  Users with the
	     ability to	bypass file permissions	on the remote host (for	the
	     agent's Unix-domain socket) can access the	local agent through
	     the forwarded connection.	An attacker cannot obtain key material
	     from the agent, however they can perform operations on the	keys
	     that enable them to authenticate using the	identities loaded into
	     the agent.

     ForwardX11
	     Specifies whether X11 connections will be automatically redi-
	     rected over the secure channel and	DISPLAY	set.  The argument
	     must be ``yes'' or	``no''.	 The default is	``no''.

	     X11 forwarding should be enabled with caution.  Users with	the
	     ability to	bypass file permissions	on the remote host (for	the
	     user's X11	authorization database)	can access the local X11 dis-
	     play through the forwarded	connection.  An	attacker may then be
	     able to perform activities	such as	keystroke monitoring if	the
	     ForwardX11Trusted option is also enabled.

     ForwardX11Timeout
	     Specify a timeout for untrusted X11 forwarding using the format
	     described in the TIME FORMATS section of sshd_config(5).  X11
	     connections received by ssh(1) after this time will be refused.
	     The default is to disable untrusted X11 forwarding	after twenty
	     minutes has elapsed.

     ForwardX11Trusted
	     If	this option is set to ``yes'', remote X11 clients will have
	     full access to the	original X11 display.

	     If	this option is set to ``no'', remote X11 clients will be con-
	     sidered untrusted and prevented from stealing or tampering	with
	     data belonging to trusted X11 clients.  Furthermore, the xauth(1)
	     token used	for the	session	will be	set to expire after 20 min-
	     utes.  Remote clients will	be refused access after	this time.

	     The default is ``no''.

	     See the X11 SECURITY extension specification for full details on
	     the restrictions imposed on untrusted clients.

     GatewayPorts
	     Specifies whether remote hosts are	allowed	to connect to local
	     forwarded ports.  By default, ssh(1) binds	local port forwardings
	     to	the loopback address.  This prevents other remote hosts	from
	     connecting	to forwarded ports.  GatewayPorts can be used to spec-
	     ify that ssh should bind local port forwardings to	the wildcard
	     address, thus allowing remote hosts to connect to forwarded
	     ports.  The argument must be ``yes'' or ``no''.  The default is
	     ``no''.

     GlobalKnownHostsFile
	     Specifies one or more files to use	for the	global host key	data-
	     base, separated by	whitespace.  The default is
	     /etc/ssh/ssh_known_hosts, /etc/ssh/ssh_known_hosts2.

     GSSAPIAuthentication
	     Specifies whether user authentication based on GSSAPI is allowed.
	     The default is ``no''.  Note that this option applies to protocol
	     version 2 only.

     GSSAPIDelegateCredentials
	     Forward (delegate)	credentials to the server.  The	default	is
	     ``no''.  Note that	this option applies to protocol	version	2
	     only.

     HashKnownHosts
	     Indicates that ssh(1) should hash host names and addresses	when
	     they are added to ~/.ssh/known_hosts.  These hashed names may be
	     used normally by ssh(1) and sshd(8), but they do not reveal iden-
	     tifying information should	the file's contents be disclosed.  The
	     default is	``no''.	 Note that existing names and addresses	in
	     known hosts files will not	be converted automatically, but	may be
	     manually hashed using ssh-keygen(1).

     HostbasedAuthentication
	     Specifies whether to try rhosts based authentication with public
	     key authentication.  The argument must be ``yes'' or ``no''.  The
	     default is	``no''.	 This option applies to	protocol version 2
	     only and is similar to RhostsRSAAuthentication.

     HostKeyAlgorithms
	     Specifies the protocol version 2 host key algorithms that the
	     client wants to use in order of preference.  The default for this
	     option is:

		ecdsa-sha2-nistp256-cert-v01@openssh.com,
		ecdsa-sha2-nistp384-cert-v01@openssh.com,
		ecdsa-sha2-nistp521-cert-v01@openssh.com,
		ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,
		ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,
		ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
		ssh-rsa,ssh-dss

	     If	hostkeys are known for the destination host then this default
	     is	modified to prefer their algorithms.

     HostKeyAlias
	     Specifies an alias	that should be used instead of the real	host
	     name when looking up or saving the	host key in the	host key data-
	     base files.  This option is useful	for tunneling SSH connections
	     or	for multiple servers running on	a single host.

     HostName
	     Specifies the real	host name to log into.	This can be used to
	     specify nicknames or abbreviations	for hosts.  If the hostname
	     contains the character sequence `%h', then	this will be replaced
	     with the host name	specified on the command line (this is useful
	     for manipulating unqualified names).  The default is the name
	     given on the command line.	 Numeric IP addresses are also permit-
	     ted (both on the command line and in HostName specifications).

     IdentitiesOnly
	     Specifies that ssh(1) should only use the authentication identity
	     files configured in the ssh_config	files, even if ssh-agent(1) or
	     a PKCS11Provider offers more identities.  The argument to this
	     keyword must be ``yes'' or	``no''.	 This option is	intended for
	     situations	where ssh-agent	offers many different identities.  The
	     default is	``no''.

     IdentityFile
	     Specifies a file from which the user's DSA, ECDSA or RSA authen-
	     tication identity is read.	 The default is	~/.ssh/identity	for
	     protocol version 1, and ~/.ssh/id_dsa, ~/.ssh/id_ecdsa and
	     ~/.ssh/id_rsa for protocol	version	2.  Additionally, any identi-
	     ties represented by the authentication agent will be used for
	     authentication.  ssh(1) will try to load certificate information
	     from the filename obtained	by appending -cert.pub to the path of
	     a specified IdentityFile.

	     The file name may use the tilde syntax to refer to	a user's home
	     directory or one of the following escape characters: `%d' (local
	     user's home directory), `%u' (local user name), `%l' (local host
	     name), `%h' (remote host name) or `%r' (remote user name).

	     It	is possible to have multiple identity files specified in con-
	     figuration	files; all these identities will be tried in sequence.
	     Multiple IdentityFile directives will add to the list of identi-
	     ties tried	(this behaviour	differs	from that of other configura-
	     tion directives).

     IPQoS   Specifies the IPv4	type-of-service	or DSCP	class for connections.
	     Accepted values are ``af11'', ``af12'', ``af13'', ``af21'',
	     ``af22'', ``af23'', ``af31'', ``af32'', ``af33'', ``af41'',
	     ``af42'', ``af43'', ``cs0'', ``cs1'', ``cs2'', ``cs3'', ``cs4'',
	     ``cs5'', ``cs6'', ``cs7'',	``ef'',	``lowdelay'', ``throughput'',
	     ``reliability'', or a numeric value.  This	option may take	one or
	     two arguments, separated by whitespace.  If one argument is spec-
	     ified, it is used as the packet class unconditionally.  If	two
	     values are	specified, the first is	automatically selected for
	     interactive sessions and the second for non-interactive sessions.
	     The default is ``lowdelay'' for interactive sessions and
	     ``throughput'' for	non-interactive	sessions.

     KbdInteractiveAuthentication
	     Specifies whether to use keyboard-interactive authentication.
	     The argument to this keyword must be ``yes'' or ``no''.  The
	     default is	``yes''.

     KbdInteractiveDevices
	     Specifies the list	of methods to use in keyboard-interactive
	     authentication.  Multiple method names must be comma-separated.
	     The default is to use the server specified	list.  The methods
	     available vary depending on what the server supports.  For	an
	     OpenSSH server, it	may be zero or more of:	``bsdauth'', ``pam'',
	     and ``skey''.

     KexAlgorithms
	     Specifies the available KEX (Key Exchange)	algorithms.  Multiple
	     algorithms	must be	comma-separated.  The default is:

		   ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
		   diffie-hellman-group-exchange-sha256,
		   diffie-hellman-group-exchange-sha1,
		   diffie-hellman-group14-sha1,
		   diffie-hellman-group1-sha1

     LocalCommand
	     Specifies a command to execute on the local machine after suc-
	     cessfully connecting to the server.  The command string extends
	     to	the end	of the line, and is executed with the user's shell.
	     The following escape character substitutions will be performed:
	     `%d' (local user's	home directory), `%h' (remote host name), `%l'
	     (local host name),	`%n' (host name	as provided on the command
	     line), `%p' (remote port),	`%r' (remote user name)	or `%u'	(local
	     user name).

	     The command is run	synchronously and does not have	access to the
	     session of	the ssh(1) that	spawned	it.  It	should not be used for
	     interactive commands.

	     This directive is ignored unless PermitLocalCommand has been
	     enabled.

     LocalForward
	     Specifies that a TCP port on the local machine be forwarded over
	     the secure	channel	to the specified host and port from the	remote
	     machine.  The first argument must be [bind_address:]port and the
	     second argument must be host:hostport.  IPv6 addresses can	be
	     specified by enclosing addresses in square	brackets.  Multiple
	     forwardings may be	specified, and additional forwardings can be
	     given on the command line.	 Only the superuser can	forward	privi-
	     leged ports.  By default, the local port is bound in accordance
	     with the GatewayPorts setting.  However, an explicit bind_address
	     may be used to bind the connection	to a specific address.	The
	     bind_address of ``localhost'' indicates that the listening	port
	     be	bound for local	use only, while	an empty address or `*'	indi-
	     cates that	the port should	be available from all interfaces.

     LogLevel
	     Gives the verbosity level that is used when logging messages from
	     ssh(1).  The possible values are: QUIET, FATAL, ERROR, INFO, VER-
	     BOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3.  The default is INFO.
	     DEBUG and DEBUG1 are equivalent.  DEBUG2 and DEBUG3 each specify
	     higher levels of verbose output.

     MACs    Specifies the MAC (message	authentication code) algorithms	in
	     order of preference.  The MAC algorithm is	used in	protocol ver-
	     sion 2 for	data integrity protection.  Multiple algorithms	must
	     be	comma-separated.  The algorithms that contain ``-etm'' calcu-
	     late the MAC after	encryption (encrypt-then-mac).	These are con-
	     sidered safer and their use recommended.  The default is:

		   hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,
		   umac-64-etm@openssh.com,umac-128-etm@openssh.com,
		   hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,
		   hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,
		   hmac-md5-96-etm@openssh.com,
		   hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,
		   hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,
		   hmac-sha1-96,hmac-md5-96

     NoHostAuthenticationForLocalhost
	     This option can be	used if	the home directory is shared across
	     machines.	In this	case localhost will refer to a different
	     machine on	each of	the machines and the user will get many	warn-
	     ings about	changed	host keys.  However, this option disables host
	     authentication for	localhost.  The	argument to this keyword must
	     be	``yes''	or ``no''.  The	default	is to check the	host key for
	     localhost.

     NumberOfPasswordPrompts
	     Specifies the number of password prompts before giving up.	 The
	     argument to this keyword must be an integer.  The default is 3.

     PasswordAuthentication
	     Specifies whether to use password authentication.	The argument
	     to	this keyword must be ``yes'' or	``no''.	 The default is
	     ``yes''.

     PermitLocalCommand
	     Allow local command execution via the LocalCommand	option or
	     using the !command	escape sequence	in ssh(1).  The	argument must
	     be	``yes''	or ``no''.  The	default	is ``no''.

     PKCS11Provider
	     Specifies which PKCS#11 provider to use.  The argument to this
	     keyword is	the PKCS#11 shared library ssh(1) should use to	commu-
	     nicate with a PKCS#11 token providing the user's private RSA key.

     Port    Specifies the port	number to connect on the remote	host.  The
	     default is	22.

     PreferredAuthentications
	     Specifies the order in which the client should try	protocol 2
	     authentication methods.  This allows a client to prefer one
	     method (e.g. keyboard-interactive)	over another method (e.g.
	     password).	 The default is:

		   gssapi-with-mic,hostbased,publickey,
		   keyboard-interactive,password

     Protocol
	     Specifies the protocol versions ssh(1) should support in order of
	     preference.  The possible values are `1' and `2'.	Multiple ver-
	     sions must	be comma-separated.  When this option is set to
	     ``2,1'' ssh will try version 2 and	fall back to version 1 if ver-
	     sion 2 is not available.  The default is `2'.

     ProxyCommand
	     Specifies the command to use to connect to	the server.  The com-
	     mand string extends to the	end of the line, and is	executed with
	     the user's	shell.	In the command string, any occurrence of `%h'
	     will be substituted by the	host name to connect, `%p' by the
	     port, and `%r' by the remote user name.  The command can be basi-
	     cally anything, and should	read from its standard input and write
	     to	its standard output.  It should	eventually connect an sshd(8)
	     server running on some machine, or	execute	sshd -i	somewhere.
	     Host key management will be done using the	HostName of the	host
	     being connected (defaulting to the	name typed by the user).  Set-
	     ting the command to ``none'' disables this	option entirely.  Note
	     that CheckHostIP is not available for connects with a proxy com-
	     mand.

	     This directive is useful in conjunction with nc(1)	and its	proxy
	     support.  For example, the	following directive would connect via
	     an	HTTP proxy at 192.0.2.0:

		ProxyCommand /usr/bin/nc -X connect -x 192.0.2.0:8080 %h %p

     PubkeyAuthentication
	     Specifies whether to try public key authentication.  The argument
	     to	this keyword must be ``yes'' or	``no''.	 The default is
	     ``yes''.  This option applies to protocol version 2 only.

     RekeyLimit
	     Specifies the maximum amount of data that may be transmitted
	     before the	session	key is renegotiated.  The argument is the num-
	     ber of bytes, with	an optional suffix of `K', `M',	or `G' to
	     indicate Kilobytes, Megabytes, or Gigabytes, respectively.	 The
	     default is	between	`1G' and `4G', depending on the	cipher.	 This
	     option applies to protocol	version	2 only.

     RemoteForward
	     Specifies that a TCP port on the remote machine be	forwarded over
	     the secure	channel	to the specified host and port from the	local
	     machine.  The first argument must be [bind_address:]port and the
	     second argument must be host:hostport.  IPv6 addresses can	be
	     specified by enclosing addresses in square	brackets.  Multiple
	     forwardings may be	specified, and additional forwardings can be
	     given on the command line.	 Privileged ports can be forwarded
	     only when logging in as root on the remote	machine.

	     If	the port argument is `0', the listen port will be dynamically
	     allocated on the server and reported to the client	at run time.

	     If	the bind_address is not	specified, the default is to only bind
	     to	loopback addresses.  If	the bind_address is `*'	or an empty
	     string, then the forwarding is requested to listen	on all inter-
	     faces.  Specifying	a remote bind_address will only	succeed	if the
	     server's GatewayPorts option is enabled (see sshd_config(5)).

     RequestTTY
	     Specifies whether to request a pseudo-tty for the session.	 The
	     argument may be one of: ``no'' (never request a TTY), ``yes''
	     (always request a TTY when	standard input is a TTY), ``force''
	     (always request a TTY) or ``auto''	(request a TTY when opening a
	     login session).  This option mirrors the -t and -T	flags for
	     ssh(1).

     RhostsRSAAuthentication
	     Specifies whether to try rhosts based authentication with RSA
	     host authentication.  The argument	must be	``yes''	or ``no''.
	     The default is ``no''.  This option applies to protocol version 1
	     only and requires ssh(1) to be setuid root.

     RSAAuthentication
	     Specifies whether to try RSA authentication.  The argument	to
	     this keyword must be ``yes'' or ``no''.  RSA authentication will
	     only be attempted if the identity file exists, or an authentica-
	     tion agent	is running.  The default is ``yes''.  Note that	this
	     option applies to protocol	version	1 only.

     SendEnv
	     Specifies what variables from the local environ(7)	should be sent
	     to	the server.  Note that environment passing is only supported
	     for protocol 2.  The server must also support it, and the server
	     must be configured	to accept these	environment variables.	Refer
	     to	AcceptEnv in sshd_config(5) for	how to configure the server.
	     Variables are specified by	name, which may	contain	wildcard char-
	     acters.  Multiple environment variables may be separated by
	     whitespace	or spread across multiple SendEnv directives.  The
	     default is	not to send any	environment variables.

	     See PATTERNS for more information on patterns.

     ServerAliveCountMax
	     Sets the number of	server alive messages (see below) which	may be
	     sent without ssh(1) receiving any messages	back from the server.
	     If	this threshold is reached while	server alive messages are
	     being sent, ssh will disconnect from the server, terminating the
	     session.  It is important to note that the	use of server alive
	     messages is very different	from TCPKeepAlive (below).  The	server
	     alive messages are	sent through the encrypted channel and there-
	     fore will not be spoofable.  The TCP keepalive option enabled by
	     TCPKeepAlive is spoofable.	 The server alive mechanism is valu-
	     able when the client or server depend on knowing when a connec-
	     tion has become inactive.

	     The default value is 3.  If, for example, ServerAliveInterval
	     (see below) is set	to 15 and ServerAliveCountMax is left at the
	     default, if the server becomes unresponsive, ssh will disconnect
	     after approximately 45 seconds.  This option applies to protocol
	     version 2 only.

     ServerAliveInterval
	     Sets a timeout interval in	seconds	after which if no data has
	     been received from	the server, ssh(1) will	send a message through
	     the encrypted channel to request a	response from the server.  The
	     default is	0, indicating that these messages will not be sent to
	     the server.  This option applies to protocol version 2 only.

     StrictHostKeyChecking
	     If	this flag is set to ``yes'', ssh(1) will never automatically
	     add host keys to the ~/.ssh/known_hosts file, and refuses to con-
	     nect to hosts whose host key has changed.	This provides maximum
	     protection	against	trojan horse attacks, though it	can be annoy-
	     ing when the /etc/ssh/ssh_known_hosts file	is poorly maintained
	     or	when connections to new	hosts are frequently made.  This
	     option forces the user to manually	add all	new hosts.  If this
	     flag is set to ``no'', ssh	will automatically add new host	keys
	     to	the user known hosts files.  If	this flag is set to ``ask'',
	     new host keys will	be added to the	user known host	files only
	     after the user has	confirmed that is what they really want	to do,
	     and ssh will refuse to connect to hosts whose host	key has
	     changed.  The host	keys of	known hosts will be verified automati-
	     cally in all cases.  The argument must be ``yes'',	``no'',	or
	     ``ask''.  The default is ``ask''.

     TCPKeepAlive
	     Specifies whether the system should send TCP keepalive messages
	     to	the other side.	 If they are sent, death of the	connection or
	     crash of one of the machines will be properly noticed.  However,
	     this means	that connections will die if the route is down tempo-
	     rarily, and some people find it annoying.

	     The default is ``yes'' (to	send TCP keepalive messages), and the
	     client will notice	if the network goes down or the	remote host
	     dies.  This is important in scripts, and many users want it too.

	     To	disable	TCP keepalive messages,	the value should be set	to
	     ``no''.

     Tunnel  Request tun(4) device forwarding between the client and the
	     server.  The argument must	be ``yes'', ``point-to-point'' (layer
	     3), ``ethernet'' (layer 2), or ``no''.  Specifying	``yes''
	     requests the default tunnel mode, which is	``point-to-point''.
	     The default is ``no''.

     TunnelDevice
	     Specifies the tun(4) devices to open on the client	(local_tun)
	     and the server (remote_tun).

	     The argument must be local_tun[:remote_tun].  The devices may be
	     specified by numerical ID or the keyword ``any'', which uses the
	     next available tunnel device.  If remote_tun is not specified, it
	     defaults to ``any''.  The default is ``any:any''.

     UsePrivilegedPort
	     Specifies whether to use a	privileged port	for outgoing connec-
	     tions.  The argument must be ``yes'' or ``no''.  The default is
	     ``no''.  If set to	``yes'', ssh(1)	must be	setuid root.  Note
	     that this option must be set to ``yes'' for
	     RhostsRSAAuthentication with older	servers.

     User    Specifies the user	to log in as.  This can	be useful when a dif-
	     ferent user name is used on different machines.  This saves the
	     trouble of	having to remember to give the user name on the	com-
	     mand line.

     UserKnownHostsFile
	     Specifies one or more files to use	for the	user host key data-
	     base, separated by	whitespace.  The default is
	     ~/.ssh/known_hosts, ~/.ssh/known_hosts2.

     VerifyHostKeyDNS
	     Specifies whether to verify the remote key	using DNS and SSHFP
	     resource records.	If this	option is set to ``yes'', the client
	     will implicitly trust keys	that match a secure fingerprint	from
	     DNS.  Insecure fingerprints will be handled as if this option was
	     set to ``ask''.  If this option is	set to ``ask'',	information on
	     fingerprint match will be displayed, but the user will still need
	     to	confirm	new host keys according	to the StrictHostKeyChecking
	     option.  The argument must	be ``yes'', ``no'', or ``ask''.	 The
	     default is	``no''.	 Note that this	option applies to protocol
	     version 2 only.

	     See also VERIFYING	HOST KEYS in ssh(1).

     VersionAddendum
	     Specifies a string	to append to the regular version string	to
	     identify OS- or site-specific modifications.  The default is
	     ``FreeBSD-20130515''.

     VisualHostKey
	     If	this flag is set to ``yes'', an	ASCII art representation of
	     the remote	host key fingerprint is	printed	in addition to the hex
	     fingerprint string	at login and for unknown host keys.  If	this
	     flag is set to ``no'', no fingerprint strings are printed at
	     login and only the	hex fingerprint	string will be printed for
	     unknown host keys.	 The default is	``no''.

     XAuthLocation
	     Specifies the full	pathname of the	xauth(1) program.  The default
	     is	/usr/local/bin/xauth.

PATTERNS
     A pattern consists	of zero	or more	non-whitespace characters, `*' (a
     wildcard that matches zero	or more	characters), or	`?' (a wildcard	that
     matches exactly one character).  For example, to specify a	set of decla-
     rations for any host in the ``.co.uk'' set	of domains, the	following pat-
     tern could	be used:

	   Host	*.co.uk

     The following pattern would match any host	in the 192.168.0.[0-9] network
     range:

	   Host	192.168.0.?

     A pattern-list is a comma-separated list of patterns.  Patterns within
     pattern-lists may be negated by preceding them with an exclamation	mark
     (`!').  For example, to allow a key to be used from anywhere within an
     organisation except from the ``dialup'' pool, the following entry (in
     authorized_keys) could be used:

	   from="!*.dialup.example.com,*.example.com"

FILES
     ~/.ssh/config
	     This is the per-user configuration	file.  The format of this file
	     is	described above.  This file is used by the SSH client.
	     Because of	the potential for abuse, this file must	have strict
	     permissions: read/write for the user, and not accessible by oth-
	     ers.

     /etc/ssh/ssh_config
	     Systemwide	configuration file.  This file provides	defaults for
	     those values that are not specified in the	user's configuration
	     file, and for those users who do not have a configuration file.
	     This file must be world-readable.

SEE ALSO
     ssh(1)

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	9.2			January	8, 2013			   FreeBSD 9.2

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

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