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SSH_CONFIG(5)		    BSD	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 usually the one
     given on the command line (see the	CanonicalizeHostname option for	excep-
     tions.)

     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 sepa-
     rated by whitespace or optional whitespace	and exactly one	`='; the lat-
     ter format	is useful to avoid the need to quote whitespace	when specify-
     ing configuration options using the ssh, scp, and sftp -o option.	Argu-
     ments may optionally be enclosed in double	quotes (") in order to repre-
     sent 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 or
	     Match keyword) 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 pattern can be used to provide global	defaults for all
	     hosts.  The host is usually the hostname argument given on	the
	     command line (see the CanonicalizeHostname	option for excep-
	     tions.)

	     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 ex-
	     ceptions for wildcard matches.

	     See PATTERNS for more information on patterns.

     Match   Restricts the following declarations (up to the next Host or
	     Match keyword) to be used only when the conditions	following the
	     Match keyword are satisfied.  Match conditions are	specified us-
	     ing one or	more criteria or the single token all which always
	     matches.  The available criteria keywords are: canonical, exec,
	     host, originalhost, user, and localuser.  The all criteria	must
	     appear alone or immediately after canonical.  Other criteria may
	     be	combined arbitrarily.  All criteria but	all and	canonical re-
	     quire an argument.	 Criteria may be negated by prepending an ex-
	     clamation mark (`!').

	     The canonical keyword matches only	when the configuration file is
	     being re-parsed after hostname canonicalization (see the
	     CanonicalizeHostname option.)  This may be	useful to specify con-
	     ditions that work with canonical host names only.	The exec key-
	     word executes the specified command under the user's shell.  If
	     the command returns a zero	exit status then the condition is con-
	     sidered true.  Commands containing	whitespace characters must be
	     quoted.  The following character sequences	in the command will be
	     expanded prior to execution: `%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 specified on	the command-line, `%p'
	     the destination port, `%r'	by the remote login username, and `%u'
	     by	the username of	the user running ssh(1).

	     The other keywords' criteria must be single entries or comma-sep-
	     arated lists and may use the wildcard and negation	operators de-
	     scribed in	the PATTERNS section.  The criteria for	the host key-
	     word are matched against the target hostname, after any substitu-
	     tion by the Hostname or CanonicalizeHostname options.  The
	     originalhost keyword matches against the hostname as it was spec-
	     ified on the command-line.	 The user keyword matches against the
	     target username on	the remote host.  The localuser	keyword
	     matches against the name of the local user	running	ssh(1) (this
	     keyword may be useful in system-wide ssh_config files).

     AddKeysToAgent
	     Specifies whether keys should be automatically added to a running
	     ssh-agent(1).  If this option is set to "yes" and a key is	loaded
	     from a file, the key and its passphrase are added to the agent
	     with the default lifetime,	as if by ssh-add(1).  If this option
	     is	set to "ask", ssh will require confirmation using the
	     SSH_ASKPASS program before	adding a key (see ssh-add(1) for de-
	     tails).  If this option is	set to "confirm", each use of the key
	     must be confirmed,	as if the -c option was	specified to
	     ssh-add(1).  If this option is set	to "no", no keys are added to
	     the agent.	 The argument must be "yes", "confirm",	"ask", or
	     "no".  The	default	is "no".

     AddressFamily
	     Specifies which address family to use when	connecting.  Valid ar-
	     guments are "any",	"inet" (use IPv4 only),	or "inet6" (use	IPv6
	     only).  The default is "any".

     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 ad-
	     dress 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".

     CanonicalDomains
	     When CanonicalizeHostname is enabled, this	option specifies the
	     list of domain suffixes in	which to search	for the	specified des-
	     tination host.

     CanonicalizeFallbackLocal
	     Specifies whether to fail with an error when hostname canonical-
	     ization fails.  The default, "yes", will attempt to look up the
	     unqualified hostname using	the system resolver's search rules.  A
	     value of "no" will	cause ssh(1) to	fail instantly if
	     CanonicalizeHostname is enabled and the target hostname cannot be
	     found in any of the domains specified by CanonicalDomains.

     CanonicalizeHostname
	     Controls whether explicit hostname	canonicalization is performed.
	     The default, "no",	is not to perform any name rewriting and let
	     the system	resolver handle	all hostname lookups.  If set to "yes"
	     then, for connections that	do not use a ProxyCommand, ssh(1) will
	     attempt to	canonicalize the hostname specified on the command
	     line using	the CanonicalDomains suffixes and
	     CanonicalizePermittedCNAMEs rules.	 If CanonicalizeHostname is
	     set to "always", then canonicalization is applied to proxied con-
	     nections too.

	     If	this option is enabled,	then the configuration files are pro-
	     cessed again using	the new	target name to pick up any new config-
	     uration in	matching Host and Match	stanzas.

     CanonicalizeMaxDots
	     Specifies the maximum number of dot characters in a hostname be-
	     fore canonicalization is disabled.	 The default, "1", allows a
	     single dot	(i.e. hostname.subdomain).

     CanonicalizePermittedCNAMEs
	     Specifies rules to	determine whether CNAMEs should	be followed
	     when canonicalizing hostnames.  The rules consist of one or more
	     arguments of source_domain_list:target_domain_list, where
	     source_domain_list	is a pattern-list of domains that may follow
	     CNAMEs in canonicalization, and target_domain_list	is a pattern-
	     list of domains that they may resolve to.

	     For example, "*.a.example.com:*.b.example.com,*.c.example.com"
	     will allow	hostnames matching "*.a.example.com" to	be canonical-
	     ized to names in the "*.b.example.com" or "*.c.example.com" do-
	     mains.

     CertificateFile
	     Specifies a file from which the user's certificate	is read.  A
	     corresponding private key must be provided	separately in order to
	     use this certificate either from an IdentityFile directive	or -i
	     flag to ssh(1), via ssh-agent(1), or via a	PKCS11Provider.

	     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 certificate files specified in
	     configuration files; these	certificates will be tried in se-
	     quence.  Multiple CertificateFile directives will add to the list
	     of	certificates used for authentication.

     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 de-
	     tect if a host key	changed	due to DNS spoofing and	will add ad-
	     dresses of	destination hosts to ~/.ssh/known_hosts	in the
	     process, regardless of the	setting	of StrictHostKeyChecking.  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 sup-
	     ported.  des is only supported in the ssh(1) client for interop-
	     erability with legacy protocol 1 implementations that do not sup-
	     port 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.  If	the
	     specified value begins with a `+' character, then the specified
	     ciphers will be appended to the default set instead of replacing
	     them.

	     The supported ciphers are:

		   3des-cbc
		   aes128-cbc
		   aes192-cbc
		   aes256-cbc
		   aes128-ctr
		   aes192-ctr
		   aes256-ctr
		   aes128-gcm@openssh.com
		   aes256-gcm@openssh.com
		   arcfour
		   arcfour128
		   arcfour256
		   blowfish-cbc
		   cast128-cbc
		   chacha20-poly1305@openssh.com

	     The default is:

		   chacha20-poly1305@openssh.com,
		   aes128-ctr,aes192-ctr,aes256-ctr,
		   aes128-gcm@openssh.com,aes256-gcm@openssh.com,
		   aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc

	     The list of available ciphers may also be obtained	using the -Q
	     option of ssh(1) with an argument of "cipher".

     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 ex-
	     iting.  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 un-
	     reachable,	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 ssh-askpass(1).  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" op-
	     tion.

     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 specified on
	     the command line, `%p' the	destination port, `%r' by the remote
	     login username, `%u' by the username and `%i' by the numeric user
	     ID	(uid) of the user running ssh(1), and `%C' by a	hash of	the
	     concatenation: %l%h%p%r.  It is recommended that any ControlPath
	     used for opportunistic connection sharing include at least	%h,
	     %p, and %r	(or alternatively %C) and be placed in a directory
	     that is not writable by other users.  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 connection
	     will not be placed	into the background, and will close as soon as
	     the initial client	connection is closed.  If set to "yes" or "0",
	     then the master connection	will remain in the background indefi-
	     nitely (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 back-
	     grounded master connection	will automatically terminate after it
	     has remained idle (with no	client connections) for	the specified
	     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 disable
	     the escape	character entirely (making the connection transparent
	     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, (e.g. if	either end is unable to	bind and lis-
	     ten on a specified	port).	Note that ExitOnForwardFailure does
	     not apply to connections made over	port forwardings and will not,
	     for example, cause	ssh(1) to exit if TCP connections to the ulti-
	     mate forwarding destination fail.	The argument must be "yes" or
	     "no".  The	default	is "no".

     FingerprintHash
	     Specifies the hash	algorithm used when displaying key finger-
	     prints.  Valid options are: "md5" and "sha256".  The default is
	     "sha256".

     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 consid-
	     ered untrusted and	prevented from stealing	or tampering with data
	     belonging to trusted X11 clients.	Furthermore, the xauth(1) to-
	     ken used for the session will be set to expire after 20 minutes.
	     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".

     GSSAPIDelegateCredentials
	     Forward (delegate)	credentials to the server.  The	default	is
	     "no".

     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 manu-
	     ally 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 de-
	     fault is "no".

     HostbasedKeyTypes
	     Specifies the key types that will be used for hostbased authenti-
	     cation as a comma-separated pattern list.	Alternately if the
	     specified value begins with a `+' character, then the specified
	     key types will be appended	to the default set instead of replac-
	     ing them.	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-ed25519-cert-v01@openssh.com,
		ssh-rsa-cert-v01@openssh.com,
		ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
		ssh-ed25519,ssh-rsa

	     The -Q option of ssh(1) may be used to list supported key types.

     HostKeyAlgorithms
	     Specifies the host	key algorithms that the	client wants to	use in
	     order of preference.  Alternately if the specified	value begins
	     with a `+'	character, then	the specified key types	will be	ap-
	     pended to the default set instead of replacing them.  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-ed25519-cert-v01@openssh.com,
		ssh-rsa-cert-v01@openssh.com,
		ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
		ssh-ed25519,ssh-rsa

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

	     The list of available key types may also be obtained using	the -Q
	     option of ssh(1) with an argument of "key".

     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 character sequence `%%'
	     will be replaced by a single `%' character, which may be used
	     when specifying IPv6 link-local addresses.

	     The default is the	name given on the command line.	 Numeric IP
	     addresses are also	permitted (both	on the command line and	in
	     HostName specifications).

     IdentitiesOnly
	     Specifies that ssh(1) should only use the authentication identity
	     and certificate files explicitly configured in the	ssh_config
	     files or passed on	the ssh(1) command-line, 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 situ-
	     ations where ssh-agent offers many	different identities.  The de-
	     fault is "no".

     IdentityFile
	     Specifies a file from which the user's DSA, ECDSA,	Ed25519	or RSA
	     authentication identity is	read.  The default is ~/.ssh/identity
	     for protocol version 1, and ~/.ssh/id_dsa,	~/.ssh/id_ecdsa,
	     ~/.ssh/id_ed25519 and ~/.ssh/id_rsa for protocol version 2.  Ad-
	     ditionally, any identities	represented by the authentication
	     agent will	be used	for authentication unless IdentitiesOnly is
	     set.  If no certificates have been	explicitly specified by
	     CertificateFile, 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).

	     IdentityFile may be used in conjunction with IdentitiesOnly to
	     select which identities in	an agent are offered during authenti-
	     cation.  IdentityFile may also be used in conjunction with
	     CertificateFile in	order to provide any certificate also needed
	     for authentication	with the identity.

     IgnoreUnknown
	     Specifies a pattern-list of unknown options to be ignored if they
	     are encountered in	configuration parsing.	This may be used to
	     suppress errors if	ssh_config contains options that are unrecog-
	     nised by ssh(1).  It is recommended that IgnoreUnknown be listed
	     early in the configuration	file as	it will	not be applied to un-
	     known options that	appear before it.

     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 white-
	     space.  If	one argument is	specified, 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 in-
	     teractive 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 au-
	     thentication.  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.  Alternately if the specified
	     value begins with a `+' character,	then the specified methods
	     will be appended to the default set instead of replacing them.
	     The default is:

		   curve25519-sha256@libssh.org,
		   ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
		   diffie-hellman-group-exchange-sha256,
		   diffie-hellman-group-exchange-sha1,
		   diffie-hellman-group14-sha1

	     The list of available key exchange	algorithms may also be ob-
	     tained using the -Q option	of ssh(1) with an argument of "kex".

     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)	or `%C'	by a hash of the concatenation:	%l%h%p%r.

	     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 en-
	     abled.

     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 `*' indicates
	     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 or-
	     der of preference.	 The MAC algorithm is used for data integrity
	     protection.  Multiple algorithms must be comma-separated.	If the
	     specified value begins with a `+' character, then the specified
	     algorithms	will be	appended to the	default	set instead of replac-
	     ing them.

	     The algorithms that contain "-etm"	calculate the MAC after	en-
	     cryption (encrypt-then-mac).  These are considered	safer and
	     their use recommended.

	     The default is:

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

	     The list of available MAC algorithms may also be obtained using
	     the -Q option of ssh(1) with an argument of "mac".

     NoHostAuthenticationForLocalhost
	     This option can be	used if	the home directory is shared across
	     machines.	In this	case localhost will refer to a different ma-
	     chine on each of the machines and the user	will get many warnings
	     about changed host	keys.  However,	this option disables host au-
	     thentication for localhost.  The argument to this keyword must be
	     "yes" or "no".  The default is to check the host key for local-
	     host.

     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 us-
	     ing 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 de-
	     fault is 22.

     PreferredAuthentications
	     Specifies the order in which the client should try	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 version 2 is
	     not available.  The default is `2'.  Protocol 1 suffers from a
	     number of cryptographic weaknesses	and should not be used.	 It is
	     only offered to support legacy devices.

     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 using
	     the user's	shell `exec' directive to avoid	a lingering shell
	     process.

	     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 basically 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 manage-
	     ment will be done using the HostName of the host being connected
	     (defaulting to the	name typed by the user).  Setting the command
	     to	"none" disables	this option entirely.  Note that CheckHostIP
	     is	not available for connects with	a proxy	command.

	     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

     ProxyUseFdpass
	     Specifies that ProxyCommand will pass a connected file descriptor
	     back to ssh(1) instead of continuing to execute and pass data.
	     The default is "no".

     PubkeyAcceptedKeyTypes
	     Specifies the key types that will be used for public key authen-
	     tication as a comma-separated pattern list.  Alternately if the
	     specified value begins with a `+' character, then the key types
	     after it will be appended to the default instead of replacing it.
	     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-ed25519-cert-v01@openssh.com,
		ssh-rsa-cert-v01@openssh.com,
		ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
		ssh-ed25519,ssh-rsa

	     The -Q option of ssh(1) may be used to list supported key types.

     PubkeyAuthentication
	     Specifies whether to try public key authentication.  The argument
	     to	this keyword must be "yes" or "no".  The default is "yes".

     RekeyLimit
	     Specifies the maximum amount of data that may be transmitted be-
	     fore the session key is renegotiated, optionally followed a maxi-
	     mum amount	of time	that may pass before the session key is	rene-
	     gotiated.	The first argument is specified	in bytes and may have
	     a suffix of `K', `M', or `G' to indicate Kilobytes, Megabytes, or
	     Gigabytes,	respectively.  The default is between `1G' and `4G',
	     depending on the cipher.  The optional second value is specified
	     in	seconds	and may	use any	of the units documented	in the TIME
	     FORMATS section of	sshd_config(5).	 The default value for
	     RekeyLimit	is "default none", which means that rekeying is	per-
	     formed after the cipher's default amount of data has been sent or
	     received and no time based	rekeying is done.

     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 re-
	     quest a TTY) or "auto" (request a TTY when	opening	a login	ses-
	     sion).  This option mirrors the -t	and -T flags for ssh(1).

     RevokedHostKeys
	     Specifies revoked host public keys.  Keys listed in this file
	     will be refused for host authentication.  Note that if this file
	     does not exist or is not readable,	then host authentication will
	     be	refused	for all	hosts.	Keys may be specified as a text	file,
	     listing one public	key per	line, or as an OpenSSH Key Revocation
	     List (KRL)	as generated by	ssh-keygen(1).	For more information
	     on	KRLs, see the KEY REVOCATION LISTS section in ssh-keygen(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 authentication
	     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.  The server	must also support it, and the server
	     must be configured	to accept these	environment variables.	Note
	     that the TERM environment variable	is always sent whenever	a
	     pseudo-terminal is	requested as it	is required by the protocol.
	     Refer to AcceptEnv	in sshd_config(5) for how to configure the
	     server.  Variables	are specified by name, which may contain wild-
	     card characters.  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 be-
	     ing 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.

     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.

     StreamLocalBindMask
	     Sets the octal file creation mode mask (umask) used when creating
	     a Unix-domain socket file for local or remote port	forwarding.
	     This option is only used for port forwarding to a Unix-domain
	     socket file.

	     The default value is 0177,	which creates a	Unix-domain socket
	     file that is readable and writable	only by	the owner.  Note that
	     not all operating systems honor the file mode on Unix-domain
	     socket files.

     StreamLocalBindUnlink
	     Specifies whether to remove an existing Unix-domain socket	file
	     for local or remote port forwarding before	creating a new one.
	     If	the socket file	already	exists and StreamLocalBindUnlink is
	     not enabled, ssh will be unable to	forward	the port to the	Unix-
	     domain socket file.  This option is only used for port forwarding
	     to	a Unix-domain socket file.

	     The argument must be "yes"	or "no".  The default is "no".

     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 connect
	     to	hosts whose host key has changed.  This	provides maximum pro-
	     tection against trojan horse attacks, though it can be annoying
	     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 automatically	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 de-
	     fault 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".

     UpdateHostKeys
	     Specifies whether ssh(1) should accept notifications of addi-
	     tional hostkeys from the server sent after	authentication has
	     completed and add them to UserKnownHostsFile.  The	argument must
	     be	"yes", "no" (the default) or "ask".  Enabling this option al-
	     lows learning alternate hostkeys for a server and supports	grace-
	     ful key rotation by allowing a server to send replacement public
	     keys before old ones are removed.	Additional hostkeys are	only
	     accepted if the key used to authenticate the host was already
	     trusted or	explicitly accepted by the user.  If UpdateHostKeys is
	     set to "ask", then	the user is asked to confirm the modifications
	     to	the known_hosts	file.  Confirmation is currently incompatible
	     with ControlPersist, and will be disabled if it is	enabled.

	     Presently,	only sshd(8) from OpenSSH 6.8 and greater support the
	     "hostkeys@openssh.com" protocol extension used to inform the
	     client of all the server's	hostkeys.

     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 op-
	     tion 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	"yes" if compiled with LDNS and	"no" otherwise.

	     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-20161230".  The value "none" may be used to disable
	     this.

     VisualHostKey
	     If	this flag is set to "yes", an ASCII art	representation of the
	     remote host key fingerprint is printed in addition	to the finger-
	     print 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 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
     organization except from the "dialup" pool, the following entry (in au-
     thorized_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.	Be-
	     cause of the potential for	abuse, this file must have strict per-
	     missions: read/write for the user,	and not	accessible by others.

     /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.

BSD			       February	20, 2016			   BSD

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

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