Re: [gentoo-user] [OT] SSH port forwards behind restrictive firewall

[Etaoin Shrdlu]

On Tuesday 19 February 2008, Mick wrote:

> > Does your mail server at home have a real ip address? You can do
> >
> > ssh -l <username> -p 443 -N ssh.server.address -L
> > localport:mail.server.address:remoteport
> >
> > And you don't need to worry about setting up forwarding rules on the
> > router.
>
> The mail server is on the Internet, not accessible by ssh.  I intended
> to use the router to bounce the ssh connection and forward it to the
> mail server.
>
> laptop --> |firewall| --> router --> mailserver
>        ssh            ssh        ssl
>
> Essentially, thinking of using the router as a proxy server.

Ok, then Willie's command will work just fine, provided that *ssh* 
connections to port 443 or 80 of your router work (and of course, that 
your router can in turn reach the mail server on the necessary ports).

ssh -p 443 -L 1234:mail.server:25 -L 5678:mail.server:110 you@router

Would open ports 1234 and 5678 on localhost for sending and receiving 
mail respectively. If your mail server uses SSL, the use the 
corresponding ports (995 and/or 587 or whatever).

What you send to port 1234 on localhost will be forwarded by ssh to your 
router, and the router will forward the data to the mail server, port 
25. The same for port 5678.

Note that the connection between your computer and the router is through 
ssh, to port 443 of the router. This is the only connection you'll pass 
through the firewall, and through which all the forwarded ports will 
flow.
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