Hi Guys,

This is my first post and need your help to implement the following scenerio :

I have Centos 4.1 installed on my machine and have three nic cards working on this machine.

eth0 - the inbuild lan card
eth1 & eth2 - externally attached nic cards.

I have two ISP connections, say ABC and XYZ.
Now what I wish to do is configure the linux machine as a server such that both the connections come in the above machine and from this machine they leave for the working bays (workstations).

I wish to establish the above working model such that if the internet connection of ABC ISP provider is down because of any reason, then on my workstation, I can shift to the XYZ connection only by changing the gateway.
Just to remind you, I wish to have XYZ connection to be coming from the same above machine.

So I need your help to know how would it be possible to configure above architecture such that one machine will act as the central server. How will I configure gateways such that on workstation end, if I change the gateway (coming from the same machine) it should change the connection.

Please help me and let me know if above scenerio can be implemented.

Thanks in advance.

what do you mean by sayign that you change the gateway? your default gateway on each node will still be the same, i.e. that routing server is still doing the routing. Is this something you explicitly want to do, or jsut your perception of how it would work? if you check chapter 4 of lartc.org there are simple configs for dual ISP solutions where it would failover automatically, and a change wouldn't be needed. but if a change were needed, it'd be on the server, not every single node anyway. having two internal addresses for two external connections is pretty horrible really, you'd presumably need to do some form of iptables rule to keep two otherwise identical streams of traffic seperate for no apparent benefit.