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benno helped me clean up the tcp forwarding section;

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This commit is contained in:
jmc 2019-03-16 19:14:21 +00:00
parent 8e497f9e69
commit ce0bce58c0
1 changed files with 18 additions and 32 deletions
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50
usr.bin/ssh/ssh.1
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@ -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 1.401 2019/03/05 16:17:12 naddy Exp $
.Dd $Mdocdate: March 5 2019 $
.\" $OpenBSD: ssh.1,v 1.402 2019/03/16 19:14:21 jmc Exp $
.Dd $Mdocdate: March 16 2019 $
.Dt SSH 1
.Os
.Sh NAME
@ -1090,49 +1090,35 @@ Increase the verbosity
when errors are being written to stderr.
.El
.Sh TCP FORWARDING
Forwarding of arbitrary TCP connections over the secure channel can
be specified either on the command line or in a configuration file.
Forwarding of arbitrary TCP connections over a secure channel
can be specified either on the command line or in a configuration file.
One possible application of TCP forwarding is a secure connection to a
mail server; another is going through firewalls.
.Pp
In the example below, we look at encrypting communication between
an IRC client and server, even though the IRC server does not directly
support encrypted communications.
In the example below, we look at encrypting communication for an IRC client,
even though the IRC server it connects to does not directly
support encrypted communication.
This works as follows:
the user connects to the remote host using
.Nm ,
specifying a port to be used to forward connections
to the remote server.
After that it is possible to start the service which is to be encrypted
on the client machine,
connecting to the same local port,
specifying the ports to be used to forward the connection.
After that it is possible to start the program locally,
and
.Nm
will encrypt and forward the connection.
will encrypt and forward the connection to the remote server.
.Pp
The following example tunnels an IRC session from client machine
.Dq 127.0.0.1
(localhost)
to remote server
.Dq server.example.com :
.Bd -literal -offset 4n
$ ssh -f -L 1234:localhost:6667 server.example.com sleep 10
$ irc -c '#users' -p 1234 pinky 127.0.0.1
.Ed
.Pp
This tunnels a connection to IRC server
The following example tunnels an IRC session from the client
to an IRC server at
.Dq server.example.com ,
joining channel
.Dq #users ,
nickname
.Dq pinky ,
using port 1234.
It doesn't matter which port is used,
as long as it's greater than 1023
(remember, only root can open sockets on privileged ports)
and doesn't conflict with any ports already in use.
The connection is forwarded to port 6667 on the remote server,
since that's the standard port for IRC services.
using the standard IRC port, 6667:
.Bd -literal -offset 4n
$ ssh -f -L 6667:localhost:6667 server.example.com sleep 10
$ irc -c '#users' pinky IRC/127.0.0.1
.Ed
.Pp
The
.Fl f
@ -1142,7 +1128,7 @@ and the remote command
.Dq sleep 10
is specified to allow an amount of time
(10 seconds, in the example)
to start the service which is to be tunnelled.
to start the program which is going to use the tunnel.
If no connections are made within the time specified,
.Nm
will exit.