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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: ``ssh-rsa,ssh-dss''.
+
+ 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 RSA or DSA authentication
+ identity is read. The default is ~/.ssh/identity for protocol
+ version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa 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.
+
+ 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''.
+
+ 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 libary 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 4.8 August 4, 2010 OpenBSD 4.8