CentOS - Mar 2011 - centos home router-gateway network setup

Hello,

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 (192.168.1.1)
? ? ? \
? ? ???\
???_____\______________
? |? ? 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 192.168.1.1
eth2: static at 192.168.3.1

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.

-- 
Mark

I typically use one bridge per network card. I've never thought about
assigning all nics to one bridge, but I guess it can work if you managed it.


You typically only need one nic to connect to the wan, and one to the lan.

Eth2 can certainly have an IP address that's in the same range as your eth1
card. One address can be used as the gateway and the other can be used for
file sharing to keep the traffic apart, for example.

I'm not sure what you use your centos box for, but it's possible you
don't
need an eth2 at all...