real routing under nat routing
I have a network of about 6 computers, going in and out.
They are currently nat'd by a broadband 'router'.
I have an old pmac 6100 i'm using for various tasks (nagios, nessus, bind replication, etc), so it's not too busy. I want to use it as a router for the network, which simply throttles and shapes network traffic, before handing it to the nat router for transport.
The linux box has one nic, and i don't think it's desireable to route back through it, but rather have all data comming from the nat router go directly to the hosts who need it.
This works if i set the linux box as the default route on various hosts (mainly MacOS X), but only partially - the boxes will discover the broadband router at some point, and use it instead.
How can I make my scenario work?
Setting up a second NIC will be a complex operation, and theoretically doesn't seem necessary. Am I right?
Thanks in advaance!