Re: port forwarding question

Thanks, but I'd like to get a solid understanding of packet handling /
port forwarding before I replace the gateway for all the users.

On 8/5/06, Joshua D. Drake <[email protected]> wrote:
> Seth Wegner wrote:
> > I have a limited gateway that can only hold a few port forward
> > entries. I have a debian sarge box on my internal network. I have no
> > DMZ. I would like to forward a range of ports from the gateway to the
> > debian box (say 5900-5999) and then forward those ports to various
> > users on the network so they can use Ultravnc Single Click, in order
> > to work around the limitation of the gateway. I would eventually like
> > to replace the gateway with a debian box, but I thought I'd learn more
> > about how this works first. I think I'm missing a fundamental concept
> > around the traffic coming in and going out on the same network.
>
> You may want to see if your gateway can specify a dmz host. That way all
> packets are automatically directed to Debian and you use Debian to
> control everything.
>
> Joshua D. Drake
>
>
> >
> > I tried forwarding one port to the debian box, then telling the debian
> > box to forward to a workstation with the following commands, trying to
> > ultravnc single click connect from outside (a dial up connection) to
> > the listening workstation after each command. The traffic was never
> > seen on the workstation.
> >
> > $iptables -A FORWARD -i eth0 -o eth0 -p tcp --dport 5904 -m state
> > --state NEW,ESTABLISHED,RELATED -j ACCEPT
> >
> > $iptables -A PREROUTING -t nat -p tcp -d [ip of debian box] --dport
> > 5904 -m state  --state NEW,ESTABLISHED,RELATED -j DNAT --to [ip of
> > workstation]:5904
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