setting up a linux pc as a router

please tell me the steps to make linux system as a router..

i have two networks and i want to setup a linux router so that both network can communicate with each other.i have a system with 2 nic's in the network .
i am just confused what ip's to give to the 2 NICs on the router system.

now please tell me the steps.and how to make the routes permanent.
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I've done the same thing before using the following guide:

Worked like a charm!
A little more info would make this easier, such as what subnet masks you need to use?

If you are you trying to use two class C subnets such as and, you'll have to assign to have an IP address of to eth1 and alias to eth1/1.

Then, each client host on the subnet would use as its gateway and each client host on the subnet would use as its gateway respectively.

Personally, I would use two Class B subnets such as and and the client hosts on both subnets would use the eth1 gateway device on the Linux router; Granted everything is actually on a single subnet of 65535 hosts, but at least no aliasing of eth1 would be necessary

Also, IP forwarding should be setup on the linux router /etc/sysconfig/network FORWARD_IPV4="1" to load the default route at boot time.


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