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+SSH_CONFIG(5)             OpenBSD Programmer's 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
+     following 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
+     configuration 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-
+     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 optionally 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-sensitive):
+
+     Host    Restricts the following declarations (up to the next Host
+             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 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 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
+             ``yes''.
+
+     Cipher  Specifies the cipher to use for encrypting the session in
+             protocol 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
+             supported 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
+             configuration 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
+             connections on a control socket specified using the ControlPath
+             argument.  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
+             program before they are accepted (see ssh-add(1) for details).
+             If the ControlPath cannot be opened, ssh will continue without
+             connecting to a master instance.
+
+             X11 and ssh-agent(1) forwarding is supported over these
+             multiplexed 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
+             sharing 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
+             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
+             connection 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'', 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
+             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
+             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 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.  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
+             redirected 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
+             display 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
+             considered 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 forwardings
+             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
+             wildcard 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 /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
+             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 commandline (this is useful
+             for manipulating unqualified names).  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
+             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 situations where
+             ssh-agent offers many different identities.  The default is
+             ``no''.
+
+     IdentityFile
+             Specifies a file from which the user's DSA, ECDSA or DSA
+             authentication 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
+             identities 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
+             configuration files; all these identities will be tried in
+             sequence.
+
+     IPQoS   Specifies the IPv4 type-of-service or DSCP class for connections.
+             Accepted values are ``af11'', ``af12'', ``af13'', ``af14'',
+             ``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
+             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 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
+             successfully 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
+             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
+             version 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
+             warnings 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
+             communicate 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
+             command 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
+             somewhere.  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 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
+             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 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
+             interfaces.  Specifying a remote bind_address will only succeed
+             if the server's GatewayPorts option is enabled (see
+             sshd_config(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
+             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.  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
+             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
+             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
+             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 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
+             connect to hosts whose host key has changed.  This provides
+             maximum protection 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
+             temporarily, 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
+             connections.  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
+             different user name is used on different machines.  This saves
+             the trouble of having to remember to give the user name on the
+             command 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'', 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).
+
+     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/X11R6/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
+     declarations for any host in the ``.co.uk'' set of domains, the following
+     pattern 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
+             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
+     created OpenSSH.  Markus Friedl contributed the support for SSH protocol
+     versions 1.5 and 2.0.
+
+OpenBSD 4.9                    December 8, 2010                    OpenBSD 4.9