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SSH_CONFIG(5)							 SSH_CONFIG(5)

NAME
       ssh_config - OpenSSH SSH client configuration files

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

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

       1.     command-line options

       2.     user's configuration file (~/.ssh/config)

       3.     system-wide configuration file (/usr/pkg/etc/ssh/ssh_config)

	      For each parameter, the first obtained value will be used.   The
	      configuration files contain sections separated by ``Host'' spec‐
	      ifications, 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-specific 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 specifying	configuration  options
	      using  the  ssh, scp, and sftp -o option.	 Arguments may option‐
	      ally be enclosed in double quotes	 (")  in  order	 to  represent
	      arguments containing spaces.

	      The  possible  keywords  and their meanings are as follows (note
	      that keywords are case-insensitive and arguments are case-sensi‐
	      tive):

       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
	      matching).

	      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  dis‐
	      abled.   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 ``yes''.

       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'',
	      ``arcfour128'',  ``arcfour256'',	``arcfour'', ``blowfish-cbc'',
	      and ``cast128-cbc''.  The default is:

	      aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
	      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
	      connections, but require confirmation using the SSH_ASKPASS pro‐
	      gram before they are accepted (see ssh-add(1) for details).   If
	      the ControlPath cannot be opened, ssh will continue without con‐
	      necting 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
	      possible 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 local host name,	`%h'  will  be
	      substituted  by the target host name, `%p' the port, and `%r' by
	      the remote login username.  It is recommended that any  Control‐
	      Path  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 back‐
	      ground indefinitely (until killed or closed via a mechanism such
	      as  the  ssh(1)  ``Fl  O No exit'' option).  If set to a time in
	      seconds, or a time in any of the formats documented in sshd_con‐
	      fig(5),  then  the backgrounded master connection will automati‐
	      cally terminate after it has remained idle (with no client  con‐
	      nections) 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 Gateway‐
	      Ports 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.

	      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  com‐
	      mand line.  Only the superuser can forward privileged ports.

       EnableSSHKeysign
	      Setting  this  option to ``yes'' in the global client configura‐
	      tion file /usr/pkg/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  charac‐
	      ter 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.	 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	 mate‐
	      rial  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  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  forward‐
	      ings  to the loopback address.  This prevents other remote hosts
	      from connecting to forwarded ports.  GatewayPorts can be used to
	      specify that ssh should bind local port forwardings to the wild‐
	      card address, thus allowing remote hosts to connect to forwarded
	      ports.   The argument must be ``yes'' or ``no''.	The default is
	      ``no''.

       GlobalKnownHostsFile
	      Specifies a file to use for the global host key database instead
	      of /usr/pkg/etc/ssh/ssh_known_hosts.

       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
	      identifying 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
	      database files.  This option is useful for tunneling SSH connec‐
	      tions 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 commandline (this is useful
	      for manipulating unqualified names).  The default	 is  the  name
	      given  on	 the command line.  Numeric IP addresses are also per‐
	      mitted (both on the command  line	 and  in  HostName  specifica‐
	      tions).

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

       IdentityFile
	      Specifies a file from which the user's DSA, ECDSA or DSA 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.

       IPQoS  Specifies the IPv4 type-of-service or  DSCP  class  for  connec‐
	      tions.	Accepted  values  are  ``af11'',  ``af12'',  ``af13'',
	      ``af14'',	 ``af22'',  ``af23'',  ``af31'',  ``af32'',  ``af33'',
	      ``af41'',	  ``af42'',   ``af43'',	  ``cs0'',  ``cs1'',  ``cs2'',
	      ``cs3'', ``cs4'', ``cs5'', ``cs6'',  ``cs7'',  ``ef'',  ``lowde‐
	      lay'',  ``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 sec‐
	      ond 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 com‐
	      mand 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 forward‐
	      ings can be given on the command line.  Only the	superuser  can
	      forward  privileged  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,  VERBOSE,  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 default is:

	      hmac-md5,hmac-sha1,umac-64@openssh.com,
	      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 ! Ns 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  com‐
	      municate	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
	      versions 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'.

       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
	      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 some‐
	      where.  Host key management 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

       PubkeyAuthentication
	      Specifies whether to try public key authentication.   The	 argu‐
	      ment  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
	      number 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  forward‐
	      ings  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
	      interfaces.  Specifying a remote bind_address will only  succeed
	      if  the  server's	 GatewayPorts option is enabled (see sshd_con‐
	      fig(5)) .

       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  sup‐
	      ported 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 characters.  Multiple environment variables may be sep‐
	      arated by whitespace or spread across  multiple  SendEnv	direc‐
	      tives.  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 mes‐
	      sages are being sent, ssh will disconnect from the server,  ter‐
	      minating	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 therefore will not be spoofable.  The  TCP
	      keepalive	 option	 enabled  by  TCPKeepAlive  is spoofable.  The
	      server alive mechanism is valuable when  the  client  or	server
	      depend on knowing when a connection 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 ver‐
	      sion 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
	      connect to hosts whose host key has changed.  This provides max‐
	      imum  protection	against trojan horse attacks, though it can be
	      annoying	when  the  /usr/pkg/etc/ssh/ssh_known_hosts  file   is
	      poorly  maintained  or  when  connections	 to new hosts are fre‐
	      quently made.  This option forces the user to manually  add  all
	      new  hosts.   If	this flag is set to ``no'', ssh will automati‐
	      cally 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 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 RhostsRSAAuthentica‐
	      tion 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 a file to use for the user host key  database  instead
	      of ~/.ssh/known_hosts.

       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'', informa‐
	      tion on fingerprint match will be displayed, but the  user  will
	      still  need  to  confirm	new  host keys according to the Stric‐
	      tHostKeyChecking 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).

       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/pkg/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  dec‐
       larations  for any host in the ``.co.uk'' set of domains, the following
       pattern could be used:

       Dl Host *.co.uk

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

       Dl 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:

       Dl 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.

       /usr/pkg/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  created  OpenSSH.	Markus	Friedl contributed the support for SSH
       protocol versions 1.5 and 2.0.

			       December 8 2010			 SSH_CONFIG(5)
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