Hi all, we actually have two lines connecting us and our services to the Internet, a 2 mbit payed on a per traffic base, and a 512K flat payed. We have 32 IPs on the 2 mbit and 64 IPs on the second line. We cannot reconfigure or access the router. We would like to setup a linux box to create a "bridge" between the two networks so that the traffic that goes from one network to the other does not pass to the internet (i.e. we have a backup mail server and a backup dns server for net2 in net1. I would like that the messages being handled by the backup mail server pass through the linux box and not through the 2mbit line, once they arrived to the backup mail server, to avoid paying twice the traffic. The same goes for data backup, even if in this case i can put two NICs, one on each net) I know it's as easy as putting a static route on the router, pointing to the linux box. But we cannot access the routers =( I also thought about putting the route into the routing table of the mail servers. This solves the problem, but we have to put the route pointing from net1 to net2 and vice versa in each server, and we have a couple of server which are not ours and i cannot access and modify they're routes. I also thought about using the linux box as default gateway for each server in each net, and it works, but it work this way:
Net1--------------Linux----------------Net2 | Router1-------------+------------------Router2 Net1 and Net2 can share the traffic between them without accessing the Internet. If linux box has router 1 as default gateway all the traffic to the internet is routed through router1, same goes for router2 if router2 is the default gateway for the linux box. This is correct and works. What i would like to know is: Is it possible to configure the Linux box to route all the traffic originated from net1 and destined to the Internet through router1 only, and route all the traffic originated from net2 through router2 only? We also need traffic shaping and accounting, but as i see once we set up the linux box to handle the traffic, we can also account and manage it! I thought about various setup, a possible one would be using the bridging function of linux, but i understand it would work and solve the problem of firewalling and managing traffic for each net without reconfiguring the routers, not the "routing" problem. One last question: since we have two lines we would like to be able to use them each one as backup (i.e. if line1 goes down traffic is rerouted through line2) As i understand we need to be an Autonomous System to do this, and the two routers must be configured using BGP or some other dinamic routing protocol, is this correct? Thank you very much if any of you could help, or point to some links and documentation we can study and apply! Riccardo