[Sussex] Having fun with routing

[John Crowhurst]

> Hi Guys
>
> I know that there are a few of you out there with some good network
> admin skills and I need to tap into that knowledge base. :-)
>
> I've just got myself a nice little box with 3 NIC interfaces that is now
> to be my firewall.  As a result I'm re-vamping my network.  The new
> design looks like this:

If you are not using RIP to broadcast your dynamic routing table around
your network, switch it off as its extra noise on your network.

For static routing:

Laptop should use 192.168.1.1 as its default gw
Hub should use 194.222.168.155 as its default gw (change to 192.168.0.1
w/DSL)
Firewall should use 192.168.0.2 as its default gw (change to DSL router IP)

At this point, the laptop, the 10.x IP range and firewall can reach the
internet. However, the hub will think that 10.x will be available via ppp,
so we will have to add a static route for 10.x from the hub. The same will
be true when you go DSL.

I guess that you don't want to run multihomed (DSL and dialup at the same
time to connect to the internet) as routing will become mega confusing.

The static route on the hub will look like this:

~# route add -net 10.0.0.0 netmask 255.0.0.0 gw 192.168.0.1 metric 1

On the firewall (when you enable DSL):

~# route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.0.2 metric 1

Quick recap:

Laptop sees the internet via its default gw, Hub sees internet via default
gw, and same with Firewall (and everything attached to it) via default gw.

Laptop sees the Firewall via the default gw, then from the hub's static
route to the Firewall (then to everything behind it)

The Firewall sees the Laptop via the static route to the hub.

I think thats it :)
--
John