[plug] RE: Setup of Router

[The Thought Assassin]

On Mon, 2 Jul 2001, NVT Australia wrote:
> Can you help on an issue with firewalls/routers? I am using a Red Hat 7.1
> system (very nice) to set it up as a firewall and router. I can get to the
> internet ok going thru a hub which goes into a netgear router and then to an
> ADSL model. What I am trying to do is use the Red Hat 7.1 Linux machine as
> the router an illuminate the netgear router.

I am guessing you meant eliminate, not illuminate? In that case, you want
the Linux box in that position on the network where the router used to be.

Assuming you had the typical setup where everything was connected to the
hub except for the modem, and the modem is connected to a second ethernet
socket on the router, then you want to recreate that:

Connect everything on your network to the hub, except for the modem. (this
should already be the case, I imagine) Put a second ethernet card in your
router (which is now your linux box) and connect that to the modem with a
crossover cable. (probably the cable previously between netgear and modem)

Now create two networks, one for everything connected to the hub, and a
one for the second ethernet card and the modem. The chances are your old
setup was like this anyway, in which case just give your Linux machine the
same IP on each network as the netgear used to have.

Add appropriate routes so that your Linux box can see both networks, and
uses the modem as a default gateway. Turn forwarding or masquerading on,
and whatever packets come to the Linux box from the LAN should be
forwarded to the modem and out onto the 'net.

If that doesn't work, or I made an incorrect assumption about your setup,
then post some more details on the list for us to dissect.

> Greg (newbyish)

-Greg(who has been newbyish for a bit longer :)