[lug] Routing with Linux

PC Drew drewpc at colorado.edu
Thu Jun 29 16:22:05 MDT 2000

On Thu, 29 Jun 2000, Stephen G. Smith wrote:

> Network 1 is a 35 node public static IP network
> Network 2 is an 8 node public static IP network

Make sure everything is subnetted correctly:

Network 1: (
Network 2: (

> Each network is in the same building.
> Each network needs to stay in their own address space.
> Each network would like to use resources on the others network.

That's how the Internet works!

> Can a Linux based router be used to allow (through some sort of NAT)
> packets from network 1 to network 2 or network 2 to network 1 to be
> passed and still keep the same functionality of each independent network?

If you want a linux based solution, use the person who responded before me's
response.  The better solution would be to add a static route to your default
gateway.  As long as both of you share an internet connection, this'll be a 
cheap and easy way.  If you don't, you would need to buy a router.

When a user in network 1 wants to reach network 2, the host sees that the
IP address is outside what it knows about and sends the packet to its default
gateway.  When it gets to the default gateway, the router will say "oh, that
network is on this interface!" and send it out that other interface.  Then the
packet will get there.  It'll do the same thing going the other way.

> I have drawn this scenario in many different ways. I see a few ways
> to maybe complete the task. I am looking for comments on
> a best choice.
> What are the potential pitfalls?

This is the perferred way to do it because a router is doing the routing.  If you
plan on only having a small amount of traffic, then using a Linux box to do this
would be okay (in my opinion).

More information about the LUG mailing list