>I think you want a system like this layout.
> eth0 eth1
> <Internet>---<ISDN router>-----<Linux Machine>-----<Hub/Switch>----<Machine1>
> (Firewall) I
>The ISDN router should just forward any data sent to it to the machine its
Thanks for the reply, Robert. I think my problem is a bit different than the
answer you described (unless I missed something). I already have the network
up and running with a block of 32 static IP addresses. I see how what you're
suggesting would work if I were routing to a single IP and then using
masquerading, but I'm not -- I have three servers on the network, as well as a
bunch of PCs (which could be using masquerading, but are currently using
DCHP-assigned addresses from the 32 host subnet. For reasons I won't go into
here, I want to put the servers behind the firewall (rather than in a DMZ) to
provide them with some protection.
My problem is convincing the router to use the firewall machine as a gateway
for the 32 host subnet. Since the router supports RIP-2, I'm wondering if I
can use that capability to have the firewall box advertise itself as the
gateway, and have the router pick up the proper route that way. The problem
is that I've never used RIP, so I don't know if this is doable, or if it is,
how to configure it.
>The Linux machine needs two network cards setup with private IP's say
>for eth0 and 192.168.1.2 for eth1. The internal machine should all be given a
>private ip say machine1 could be given 192.168.1.5 and machine2 given
>You need to set the default gateway on the Linux machine to the IP of the
>This mean that any traffic sent here that is not for a local network machine
>be forwarded to the ISDN router which will dial out and connect and send data
>onto the Internet to it's destination.
>Now setup IP masquerading on the Linux for the internal host. On the other
>setup the DNS entries and the default gateway to the IP address of the Linux
>If you provider gives you one IP for the router and one for you actual machine.
>the number given for you machine for network adapter eth0.
>This is a simple explanation of the steps needed. If you need help on setting
> up IP
>masquerading or any other area do ask?