Better desciption of Unix domain socket forwarding.

bz#2423; ok jmc@

1 files changed, 107 insertions, 21 deletions

diff --git a/usr.bin/ssh/ssh.1 b/usr.bin/ssh/ssh.1
index fa87c279598..85a2d8734b5 100644
--- a/usr.bin/ssh/ssh.1
+++ b/usr.bin/ssh/ssh.1
@@ -33,8 +33,8 @@
 .\" (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.1,v 1.359 2015/07/10 06:21:53 markus Exp $
-.Dd $Mdocdate: July 10 2015 $
+.\" $OpenBSD: ssh.1,v 1.360 2015/07/20 15:39:52 millert Exp $
+.Dd $Mdocdate: July 20 2015 $
 .Dt SSH 1
 .Os
 .Sh NAME
@@ -52,14 +52,14 @@
 .Op Fl F Ar configfile
 .Op Fl I Ar pkcs11
 .Op Fl i Ar identity_file
-.Op Fl L Oo Ar bind_address : Oc Ns Ar port : Ns Ar host : Ns Ar hostport
+.Op Fl L Ar address
 .Op Fl l Ar login_name
 .Op Fl m Ar mac_spec
 .Op Fl O Ar ctl_cmd
 .Op Fl o Ar option
 .Op Fl p Ar port
 .Op Fl Q Cm cipher | cipher-auth | mac | kex | key | protocol-version
-.Op Fl R Oo Ar bind_address : Oc Ns Ar port : Ns Ar host : Ns Ar hostport
+.Op Fl R Ar address
 .Op Fl S Ar ctl_path
 .Op Fl W Ar host : Ns Ar port
 .Op Fl w Ar local_tun Ns Op : Ns Ar remote_tun
@@ -93,23 +93,28 @@ is specified,
 it is executed on the remote host instead of a login shell.
 .Pp
 The options are as follows:
-.Bl -tag -width Ds
+.Bl -tag -width Ds -compact
+.Pp
 .It Fl 1
 Forces
 .Nm
 to try protocol version 1 only.
+.Pp
 .It Fl 2
 Forces
 .Nm
 to try protocol version 2 only.
+.Pp
 .It Fl 4
 Forces
 .Nm
 to use IPv4 addresses only.
+.Pp
 .It Fl 6
 Forces
 .Nm
 to use IPv6 addresses only.
+.Pp
 .It Fl A
 Enables forwarding of the authentication agent connection.
 This can also be specified on a per-host basis in a configuration file.
@@ -122,14 +127,17 @@ 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.
+.Pp
 .It Fl a
 Disables forwarding of the authentication agent connection.
+.Pp
 .It Fl b Ar bind_address
 Use
 .Ar bind_address
 on the local machine as the source address
 of the connection.
 Only useful on systems with more than one address.
+.Pp
 .It Fl C
 Requests compression of all data (including stdin, stdout, stderr, and
 data for forwarded X11, TCP and
@@ -148,6 +156,7 @@ The default value can be set on a host-by-host basis in the
 configuration files; see the
 .Cm Compression
 option.
+.Pp
 .It Fl c Ar cipher_spec
 Selects the cipher specification for encrypting the session.
 .Pp
@@ -166,6 +175,7 @@ See the
 keyword in
 .Xr ssh_config 5
 for more information.
+.Pp
 .It Fl D Xo
 .Sm off
 .Oo Ar bind_address : Oc
@@ -205,10 +215,12 @@ indicates that the listening port be bound for local use only, while an
 empty address or
 .Sq *
 indicates that the port should be available from all interfaces.
+.Pp
 .It Fl E Ar log_file
 Append debug logs to
 .Ar log_file
 instead of standard error.
+.Pp
 .It Fl e Ar escape_char
 Sets the escape character for sessions with a pty (default:
 .Ql ~ ) .
@@ -221,6 +233,7 @@ and followed by itself sends the escape character once.
 Setting the character to
 .Dq none
 disables any escapes and makes the session fully transparent.
+.Pp
 .It Fl F Ar configfile
 Specifies an alternative per-user configuration file.
 If a configuration file is given on the command line,
@@ -229,6 +242,7 @@ the system-wide configuration file
 will be ignored.
 The default for the per-user configuration file is
 .Pa ~/.ssh/config .
+.Pp
 .It Fl f
 Requests
 .Nm
@@ -251,6 +265,7 @@ then a client started with
 .Fl f
 will wait for all remote port forwards to be successfully established
 before placing itself in the background.
+.Pp
 .It Fl G
 Causes
 .Nm
@@ -259,15 +274,18 @@ to print its configuration after evaluating
 and
 .Cm Match
 blocks and exit.
+.Pp
 .It Fl g
 Allows remote hosts to connect to local forwarded ports.
 If used on a multiplexed connection, then this option must be specified
 on the master process.
+.Pp
 .It Fl I Ar pkcs11
 Specify the PKCS#11 shared library
 .Nm
 should use to communicate with a PKCS#11 token providing the user's
 private RSA key.
+.Pp
 .It Fl i Ar identity_file
 Selects a file from which the identity (private key) for
 public key authentication is read.
@@ -291,33 +309,58 @@ will also try to load certificate information from the filename obtained
 by appending
 .Pa -cert.pub
 to identity filenames.
+.Pp
 .It Fl K
 Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI
 credentials to the server.
+.Pp
 .It Fl k
 Disables forwarding (delegation) of GSSAPI credentials to the server.
+.Pp
 .It Fl L Xo
 .Sm off
 .Oo Ar bind_address : Oc
 .Ar port : host : hostport
 .Sm on
 .Xc
-Specifies that the given port on the local (client) host is to be
-forwarded to the given host and port on the remote side.
-This works by allocating a socket to listen to
+.It Fl L Xo
+.Sm off
+.Oo Ar bind_address : Oc
+.Ar port : remote_socket
+.Sm on
+.Xc
+.It Fl L Xo
+.Sm off
+.Ar local_socket : host : hostport
+.Sm on
+.Xc
+.It Fl L Xo
+.Sm off
+.Ar local_socket : remote_socket
+.Sm on
+.Xc
+Specifies that connections to the given TCP port or Unix socket on the local
+(client) host are to be forwarded to the given host and port, or Unix socket,
+on the remote side.
+This works by allocating a socket to listen to either a TCP
 .Ar port
 on the local side, optionally bound to the specified
-.Ar bind_address .
-Whenever a connection is made to this port, the
+.Ar bind_address ,
+or to a Unix socket.
+Whenever a connection is made to the local port or socket, the
 connection is forwarded over the secure channel, and a connection is
-made to
+made to either
 .Ar host
 port
-.Ar hostport
+.Ar hostport ,
+or the Unix socket
+.Ar remote_socket ,
 from the remote machine.
+.Pp
 Port forwardings can also be specified in the configuration file.
-IPv6 addresses can be specified by enclosing the address in square brackets.
 Only the superuser can forward privileged ports.
+IPv6 addresses can be specified by enclosing the address in square brackets.
+.Pp
 By default, the local port is bound in accordance with the
 .Cm GatewayPorts
 setting.
@@ -332,9 +375,11 @@ indicates that the listening port be bound for local use only, while an
 empty address or
 .Sq *
 indicates that the port should be available from all interfaces.
+.Pp
 .It Fl l Ar login_name
 Specifies the user to log in as on the remote machine.
 This also may be specified on a per-host basis in the configuration file.
+.Pp
 .It Fl M
 Places the
 .Nm
@@ -353,6 +398,7 @@ Refer to the description of
 in
 .Xr ssh_config 5
 for details.
+.Pp
 .It Fl m Ar mac_spec
 Additionally, for protocol version 2 a comma-separated list of MAC
 (message authentication code) algorithms can
@@ -360,10 +406,12 @@ be specified in order of preference.
 See the
 .Cm MACs
 keyword for more information.
+.Pp
 .It Fl N
 Do not execute a remote command.
 This is useful for just forwarding ports
 (protocol version 2 only).
+.Pp
 .It Fl n
 Redirects stdin from
 .Pa /dev/null
@@ -384,6 +432,7 @@ program will be put in the background.
 needs to ask for a password or passphrase; see also the
 .Fl f
 option.)
+.Pp
 .It Fl O Ar ctl_cmd
 Control an active connection multiplexing master process.
 When the
@@ -402,6 +451,7 @@ Valid commands are:
 (request the master to exit), and
 .Dq stop
 (request the master to stop accepting further multiplexing requests).
+.Pp
 .It Fl o Ar option
 Can be used to give options in the format used in the configuration file.
 This is useful for specifying options for which there is no separate
@@ -494,10 +544,12 @@ For full details of the options listed below, and their possible values, see
 .It VisualHostKey
 .It XAuthLocation
 .El
+.Pp
 .It Fl p Ar port
 Port to connect to on the remote host.
 This can be specified on a
 per-host basis in the configuration file.
+.Pp
 .It Fl Q Cm cipher | cipher-auth | mac | kex | key | protocol-version
 Queries
 .Nm
@@ -515,25 +567,47 @@ The available features are:
 (key types) and
 .Ar protocol-version
 (supported SSH protocol versions).
+.Pp
 .It Fl q
 Quiet mode.
 Causes most warning and diagnostic messages to be suppressed.
+.Pp
 .It Fl R Xo
 .Sm off
 .Oo Ar bind_address : Oc
 .Ar port : host : hostport
 .Sm on
 .Xc
-Specifies that the given port on the remote (server) host is to be
-forwarded to the given host and port on the local side.
-This works by allocating a socket to listen to
+.It Fl R Xo
+.Sm off
+.Oo Ar bind_address : Oc
+.Ar port : local_socket
+.Sm on
+.Xc
+.It Fl R Xo
+.Sm off
+.Ar remote_socket : host : hostport
+.Sm on
+.Xc
+.It Fl R Xo
+.Sm off
+.Ar remote_socket : local_socket
+.Sm on
+.Xc
+Specifies that connections to the given TCP port or Unix socket on the remote
+(server) host are to be forwarded to the given host and port, or Unix socket,
+on the local side.
+This works by allocating a socket to listen to either a TCP
 .Ar port
-on the remote side, and whenever a connection is made to this port, the
-connection is forwarded over the secure channel, and a connection is
-made to
+or to a Unix socket on the remote side.
+Whenever a connection is made to this port or Unix socket, the
+connection is forwarded over the secure channel, and a connection
+is made to either
 .Ar host
 port
-.Ar hostport
+.Ar hostport ,
+or
+.Ar local_socket ,
 from the local machine.
 .Pp
 Port forwardings can also be specified in the configuration file.
@@ -541,7 +615,7 @@ Privileged ports can be forwarded only when
 logging in as root on the remote machine.
 IPv6 addresses can be specified by enclosing the address in square brackets.
 .Pp
-By default, the listening socket on the server will be bound to the loopback
+By default, TCP listening sockets on the server will be bound to the loopback
 interface only.
 This may be overridden by specifying a
 .Ar bind_address .
@@ -566,6 +640,7 @@ to the client at run time.
 When used together with
 .Ic -O forward
 the allocated port will be printed to the standard output.
+.Pp
 .It Fl S Ar ctl_path
 Specifies the location of a control socket for connection sharing,
 or the string
@@ -578,14 +653,17 @@ and
 in
 .Xr ssh_config 5
 for details.
+.Pp
 .It Fl s
 May be used to request invocation of a subsystem on the remote system.
 Subsystems are a feature of the SSH2 protocol which facilitate the use
 of SSH as a secure transport for other applications (eg.\&
 .Xr sftp 1 ) .
 The subsystem is specified as the remote command.
+.Pp
 .It Fl T
 Disable pseudo-terminal allocation.
+.Pp
 .It Fl t
 Force pseudo-terminal allocation.
 This can be used to execute arbitrary
@@ -596,8 +674,10 @@ Multiple
 options force tty allocation, even if
 .Nm
 has no local tty.
+.Pp
 .It Fl V
 Display the version number and exit.
+.Pp
 .It Fl v
 Verbose mode.
 Causes
@@ -609,6 +689,7 @@ Multiple
 .Fl v
 options increase the verbosity.
 The maximum is 3.
+.Pp
 .It Fl W Ar host : Ns Ar port
 Requests that standard input and output on the client be forwarded to
 .Ar host
@@ -622,6 +703,7 @@ Implies
 and
 .Cm ClearAllForwardings .
 Works with Protocol version 2 only.
+.Pp
 .It Fl w Xo
 .Ar local_tun Ns Op : Ns Ar remote_tun
 .Xc
@@ -651,6 +733,7 @@ If the
 .Cm Tunnel
 directive is unset, it is set to the default tunnel mode, which is
 .Dq point-to-point .
+.Pp
 .It Fl X
 Enables X11 forwarding.
 This can also be specified on a per-host basis in a configuration file.
@@ -671,12 +754,15 @@ option and the
 directive in
 .Xr ssh_config 5
 for more information.
+.Pp
 .It Fl x
 Disables X11 forwarding.
+.Pp
 .It Fl Y
 Enables trusted X11 forwarding.
 Trusted X11 forwardings are not subjected to the X11 SECURITY extension
 controls.
+.Pp
 .It Fl y
 Send log information using the
 .Xr syslog 3