- djm@cvs.openbsd.org 2010/01/30 02:54:53

[openssh.git] / ssh_config.5

diff --git a/ssh_config.5 b/ssh_config.5
index 40fef73cfc3fca56b7c6fc9e644bf3f6e59e0235..7d577360dc0b0c41ae424e284d6f4b7e3313c657 100644 (file)
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -34,18 +34,16 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"

-.\" $OpenBSD: ssh_config.5,v 1.84 2006/02/24 23:20:07 jmc Exp $
-.Dd September 25, 1999
+.\" $OpenBSD: ssh_config.5,v 1.126 2010/01/09 23:04:13 dtucker Exp $
+.Dd $Mdocdate$

 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
 .Nm ssh_config
 .Nd OpenSSH SSH client configuration files
 .Sh SYNOPSIS
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
 .Nm ssh_config
 .Nd OpenSSH SSH client configuration files
 .Sh SYNOPSIS

-.Bl -tag -width Ds -compact
-.It Pa ~/.ssh/config
-.It Pa /etc/ssh/ssh_config
-.El
+.Nm ~/.ssh/config
+.Nm /etc/ssh/ssh_config

 .Sh DESCRIPTION
 .Xr ssh 1
 obtains configuration data from the following sources in
 .Sh DESCRIPTION
 .Xr ssh 1
 obtains configuration data from the following sources in


@@ -73,42 +71,7 @@ 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.
 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.

-.Sh PATTERNS
-A
-.Em pattern
-consists of zero or more non-whitespace characters,
-.Sq *
-(a wildcard that matches zero or more characters),
-or
-.Sq ?\&
-(a wildcard that matches exactly one character).
-For example, to specify a set of declarations for any host in the
-.Dq .co.uk
-set of domains,
-the following pattern could be used:
-.Pp
-.Dl Host *.co.uk
-.Pp
-The following pattern
-would match any host in the 192.168.0.[0-9] network range:
-.Pp
-.Dl Host 192.168.0.?
-.Pp
-A
-.Em pattern-list
-is a comma-separated list of patterns.
-Patterns within pattern-lists may be negated
-by preceding them with an exclamation mark
-.Pq Sq !\& .
-For example,
-to allow a key to be used from anywhere within an organisation
-except from the
-.Dq dialup
-pool,
-the following entry (in authorized_keys) could be used:

 .Pp
 .Pp

-.Dl from=\&"!*.dialup.example.com,*.example.com\&"
-.Sh FILE FORMAT

 The configuration file has the following format:
 .Pp
 Empty lines and lines starting with
 The configuration file has the following format:
 .Pp
 Empty lines and lines starting with


@@ -122,11 +85,14 @@ optional whitespace and exactly one
 the latter format is useful to avoid the need to quote whitespace
 when specifying configuration options using the
 .Nm ssh ,
 the latter format is useful to avoid the need to quote whitespace
 when specifying configuration options using the
 .Nm ssh ,

-.Nm scp
+.Nm scp ,

 and
 .Nm sftp
 .Fl o
 option.
 and
 .Nm sftp
 .Fl o
 option.

+Arguments may optionally be enclosed in double quotes
+.Pq \&"
+in order to represent arguments containing spaces.

 .Pp
 The possible
 keywords and their meanings are as follows (note that
 .Pp
 The possible
 keywords and their meanings are as follows (note that


@@ -137,6 +103,7 @@ Restricts the following declarations (up to the next
 .Cm Host
 keyword) to be only for those hosts that match one of the patterns
 given after the keyword.
 .Cm 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
 .Ql *
 as a pattern can be used to provide global
 A single
 .Ql *
 as a pattern can be used to provide global


@@ -237,9 +204,9 @@ and
 .Dq cast128-cbc .
 The default is:
 .Bd -literal -offset 3n
 .Dq cast128-cbc .
 The default is:
 .Bd -literal -offset 3n

-aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,
-arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr,
-aes192-ctr,aes256-ctr
+aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
+aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
+aes256-cbc,arcfour

 .Ed
 .It Cm ClearAllForwardings
 Specifies that all local, remote, and dynamic port forwardings
 .Ed
 .It Cm ClearAllForwardings
 Specifies that all local, remote, and dynamic port forwardings


@@ -417,6 +384,17 @@ followed by a letter, or
 to disable the escape
 character entirely (making the connection transparent for binary
 data).
 to disable the escape
 character entirely (making the connection transparent for binary
 data).

+.It Cm ExitOnForwardFailure
+Specifies whether
+.Xr ssh 1
+should terminate the connection if it cannot set up all requested
+dynamic, tunnel, local, and remote port forwardings.
+The argument must be
+.Dq yes
+or
+.Dq no .
+The default is
+.Dq no .

 .It Cm ForwardAgent
 Specifies whether the connection to the authentication agent (if any)
 will be forwarded to the remote machine.
 .It Cm ForwardAgent
 Specifies whether the connection to the authentication agent (if any)
 will be forwarded to the remote machine.


@@ -518,8 +496,9 @@ but they do not reveal identifying information should the file's contents
 be disclosed.
 The default is
 .Dq no .
 be disclosed.
 The default is
 .Dq no .

-Note that hashing of names and addresses will not be retrospectively applied
-to existing known hosts files, but these may be manually hashed using
+Note that existing names and addresses in known hosts files
+will not be converted automatically,
+but may be manually hashed using

 .Xr ssh-keygen 1 .
 .It Cm HostbasedAuthentication
 Specifies whether to try rhosts based authentication with public key
 .Xr ssh-keygen 1 .
 .It Cm HostbasedAuthentication
 Specifies whether to try rhosts based authentication with public key


@@ -580,20 +559,70 @@ and
 for protocol version 2.
 Additionally, any identities represented by the authentication agent
 will be used for authentication.
 for protocol version 2.
 Additionally, any identities represented by the authentication agent
 will be used for authentication.

+.Pp

 The file name may use the tilde
 The file name may use the tilde

-syntax to refer to a user's home directory.
+syntax to refer to a user's home directory or one of the following
+escape characters:
+.Ql %d
+(local user's home directory),
+.Ql %u
+(local user name),
+.Ql %l
+(local host name),
+.Ql %h
+(remote host name) or
+.Ql %r
+(remote user name).
+.Pp

 It is possible to have
 multiple identity files specified in configuration files; all these
 identities will be tried in sequence.
 It is possible to have
 multiple identity files specified in configuration files; all these
 identities will be tried in sequence.

+.It Cm KbdInteractiveAuthentication
+Specifies whether to use keyboard-interactive authentication.
+The argument to this keyword must be
+.Dq yes
+or
+.Dq no .
+The default is
+.Dq yes .

 .It Cm 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.
 .It Cm 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:
+.Dq bsdauth ,
+.Dq pam ,
+and
+.Dq skey .

 .It Cm 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
 .It Cm 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

-.Pa /bin/sh .
+the user's shell.
+The following escape character substitutions will be performed:
+.Ql %d
+(local user's home directory),
+.Ql %h
+(remote host name),
+.Ql %l
+(local host name),
+.Ql %n
+(host name as provided on the command line),
+.Ql %p
+(remote port),
+.Ql %r
+(remote user name) or
+.Ql %u
+(local user name).
+.Pp
+The command is run synchronously and does not have access to the
+session of the
+.Xr ssh 1
+that spawned it.
+It should not be used for interactive commands.
+.Pp

 This directive is ignored unless
 .Cm PermitLocalCommand
 has been enabled.
 This directive is ignored unless
 .Cm PermitLocalCommand
 has been enabled.


@@ -643,7 +672,10 @@ The MAC algorithm is used in protocol version 2
 for data integrity protection.
 Multiple algorithms must be comma-separated.
 The default is:
 for data integrity protection.
 Multiple algorithms must be comma-separated.
 The default is:

-.Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
+.Bd -literal -offset indent
+hmac-md5,hmac-sha1,umac-64@openssh.com,
+hmac-ripemd160,hmac-sha1-96,hmac-md5-96
+.Ed

 .It Cm 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
 .It Cm 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


@@ -690,7 +722,12 @@ This allows a client to prefer one method (e.g.\&
 over another method (e.g.\&
 .Cm password )
 The default for this option is:
 over another method (e.g.\&
 .Cm password )
 The default for this option is:

-.Dq hostbased,publickey,keyboard-interactive,password .
+.Do gssapi-with-mic ,
+hostbased,
+publickey,
+keyboard-interactive,
+password
+.Dc .

 .It Cm Protocol
 Specifies the protocol versions
 .Xr ssh 1
 .It Cm Protocol
 Specifies the protocol versions
 .Xr ssh 1


@@ -700,16 +737,18 @@ The possible values are
 and
 .Sq 2 .
 Multiple versions must be comma-separated.
 and
 .Sq 2 .
 Multiple versions must be comma-separated.

-The default is
-.Dq 2,1 .
-This means that ssh
-tries version 2 and falls back to version 1
+When this option is set to
+.Dq 2,1
+.Nm ssh
+will try version 2 and fall back to version 1

 if version 2 is not available.
 if version 2 is not available.

+The default is
+.Sq 2 .

 .It Cm 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
 .It Cm 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

-.Pa /bin/sh .
+the user's shell.

 In the command string,
 .Ql %h
 will be substituted by the host name to
 In the command string,
 .Ql %h
 will be substituted by the host name to


@@ -781,7 +820,15 @@ and
 .Ar host Ns / Ns Ar hostport .
 Multiple forwardings may be specified, and additional
 forwardings can be given on the command line.
 .Ar host Ns / Ns Ar hostport .
 Multiple forwardings may be specified, and additional
 forwardings can be given on the command line.

-Only the superuser can forward privileged ports.
+Privileged ports can be forwarded only when
+logging in as root on the remote machine.
+.Pp
+If the
+.Ar port
+argument is
+.Ql 0 ,
+the listen port will be dynamically allocated on the server and reported
+to the client at run time.

 .Pp
 If the
 .Ar bind_address
 .Pp
 If the
 .Ar bind_address


@@ -870,6 +917,7 @@ If, for example,
 .Cm ServerAliveCountMax
 is left at the default, if the server becomes unresponsive,
 ssh will disconnect after approximately 45 seconds.
 .Cm 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.

 .It Cm ServerAliveInterval
 Sets a timeout interval in seconds after which if no data has been received
 from the server,
 .It Cm ServerAliveInterval
 Sets a timeout interval in seconds after which if no data has been received
 from the server,


@@ -937,24 +985,44 @@ This is important in scripts, and many users want it too.
 To disable TCP keepalive messages, the value should be set to
 .Dq no .
 .It Cm Tunnel
 To disable TCP keepalive messages, the value should be set to
 .Dq no .
 .It Cm Tunnel

-Request starting
+Request

 .Xr tun 4
 device forwarding between the client and the server.
 .Xr tun 4
 device forwarding between the client and the server.

-This option also allows requesting layer 2 (ethernet)
-instead of layer 3 (point-to-point) tunneling from the server.

 The argument must be
 .Dq yes ,
 The argument must be
 .Dq yes ,

-.Dq point-to-point ,
-.Dq ethernet ,
+.Dq point-to-point
+(layer 3),
+.Dq ethernet
+(layer 2),

 or
 .Dq no .
 or
 .Dq no .

+Specifying
+.Dq yes
+requests the default tunnel mode, which is
+.Dq point-to-point .

 The default is
 .Dq no .
 .It Cm TunnelDevice
 The default is
 .Dq no .
 .It Cm TunnelDevice

-Force a specified
+Specifies the

 .Xr tun 4
 .Xr tun 4

-device on the client.
-Without this option, the next available device will be used.
+devices to open on the client
+.Pq Ar local_tun
+and the server
+.Pq Ar remote_tun .
+.Pp
+The argument must be
+.Sm off
+.Ar local_tun Op : Ar remote_tun .
+.Sm on
+The devices may be specified by numerical ID or the keyword
+.Dq any ,
+which uses the next available tunnel device.
+If
+.Ar remote_tun
+is not specified, it defaults to
+.Dq any .
+The default is
+.Dq any:any .

 .It Cm UsePrivilegedPort
 Specifies whether to use a privileged port for outgoing connections.
 The argument must be
 .It Cm UsePrivilegedPort
 Specifies whether to use a privileged port for outgoing connections.
 The argument must be


@@ -1009,6 +1077,18 @@ See also
 .Sx VERIFYING HOST KEYS
 in
 .Xr ssh 1 .
 .Sx VERIFYING HOST KEYS
 in
 .Xr ssh 1 .

+.It Cm VisualHostKey
+If this flag is set to
+.Dq 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
+.Dq no ,
+no fingerprint strings are printed at login and
+only the hex fingerprint string will be printed for unknown host keys.
+The default is
+.Dq no .

 .It Cm XAuthLocation
 Specifies the full pathname of the
 .Xr xauth 1
 .It Cm XAuthLocation
 Specifies the full pathname of the
 .Xr xauth 1


@@ -1016,6 +1096,41 @@ program.
 The default is
 .Pa /usr/X11R6/bin/xauth .
 .El
 The default is
 .Pa /usr/X11R6/bin/xauth .
 .El

+.Sh PATTERNS
+A
+.Em pattern
+consists of zero or more non-whitespace characters,
+.Sq *
+(a wildcard that matches zero or more characters),
+or
+.Sq ?\&
+(a wildcard that matches exactly one character).
+For example, to specify a set of declarations for any host in the
+.Dq .co.uk
+set of domains,
+the following pattern could be used:
+.Pp
+.Dl Host *.co.uk
+.Pp
+The following pattern
+would match any host in the 192.168.0.[0-9] network range:
+.Pp
+.Dl Host 192.168.0.?
+.Pp
+A
+.Em pattern-list
+is a comma-separated list of patterns.
+Patterns within pattern-lists may be negated
+by preceding them with an exclamation mark
+.Pq Sq !\& .
+For example,
+to allow a key to be used from anywhere within an organisation
+except from the
+.Dq dialup
+pool,
+the following entry (in authorized_keys) could be used:
+.Pp
+.Dl from=\&"!*.dialup.example.com,*.example.com\&"

 .Sh FILES
 .Bl -tag -width Ds
 .It Pa ~/.ssh/config
 .Sh FILES
 .Bl -tag -width Ds
 .It Pa ~/.ssh/config