[MLUG - DISCUSSION] IPTABLES - Router help

[Brandon West <EMAIL:PROTECTED>]

A re-send. I don't think it went through the first times. Sorry in advance 
for a duplicate.

I knew how to configure a router via ipchains, but haven't used iptables in the 
same manner to do this.

This is my setup: eth0 192.168.0.1
		  eth1 192.168.1.1

I have comptuers on the "0" subnet as well as the "1" subnet. So I need to get 
linux to route the packets to/from the client 192.168.1.10 to the server on 
192.168.0.10.

For example what I'd do in the past is this:
ipchains -I forward -j ACCEPT -s 192.168.1.0/24 -d  192.168.0.0/24 -b

That would allow the linux box to then allow data to be moved across the two 
different subnets.

While this is a simple example of what I need to do, in reality, I have 4 
subnets that need to be routed, say 192.168.0.0, 192.168.1.0, 192.168.2.0 and 
192.168.3.0.

So my ipchains commands to route this network would be:
#routes from 0 to 1
ipchains -I forward -j ACCEPT -s 192.168.0.0/24 -d  192.168.1.0/24 -b
#routes from 0 to 2
ipchains -I forward -j ACCEPT -s 192.168.0.0/24 -d  192.168.2.0/24 -b
#routes from 0 to 3
ipchains -I forward -j ACCEPT -s 192.168.0.0/24 -d  192.168.3.0/24 -b
#routes from 1 to 2
ipchains -I forward -j ACCEPT -s 192.168.1.0/24 -d  192.168.2.0/24 -b
#routes from 1 to 3
ipchains -I forward -j ACCEPT -s 192.168.1.0/24 -d  192.168.3.0/24 -b
#routes from 2 to 3
ipchains -I forward -j ACCEPT -s 192.168.2.0/24 -d  192.168.3.0/24 -b

Thus the above example allows all the subnets to talk to eachother.

Then back in the day of ipchains I used to setup a script of some sort with the 
above info in it, so that when you rebooted your router would work. Is there a 
way to write this to the default table upon boot?


Thanks in advance,

Brandon


PS, I only need to know how to use iptables in the first example, I can figure 
out everything else from there.



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