[CentOS] centos home router-gateway network setup

Wed Mar 9 00:19:32 UTC 2011
Mark Pryor <tlviewer at yahoo.com>


In the last 3 days I setup my SOHO in 2 ways

(1) attempt using a retail wifi/router by Netgear. The wifi is not
part of this question.

WAN (TW Cable modem)
Netgear (
  |    eth0            |
  |      \             |
  |       \--br0--eth2 |
  |           |        |
  | C5.5     eth1      |
  |         /          |
  |_______ /___________| 
       LAN (switch upstairs)

above is my first setup for SOHO network. Only br0 had an IP (dynamic). All of the nics had proto None and were slaved to br0. This is a very easy setup.

The whole network, from Netgear to LAN and beyond, is one subnet.

(2) attempt - permanently remove the Netgear and have C5.5 do all the services- gateway, router, dhcp, and firewall.

The only way I could get this to work was with no bridging at all. Each nic needed an IP and all on different subnets.

eth0: dynamic from TW WAN
eth1: static at
eth2: static at

Using the lokkit firewall tool and adding NAT/Masquerade to eth0 this worked. 

My question is: is there a way avoid a wasted IP at eth2 and somehow bridge it to or with eth1 so only one subnet is possible inside the LAN?

I know I need at least one static IP on one of the nics for the gateway.