[TriLUG] Linux Routing - why isn't it working?

[Brian Blater]

Hi all,

I know this has got to be something simple, but I just can't figure out
what is wrong.

I have an Ubuntu 12.04 server that has two nics. Eth0 connects to the main
network and Eth1 connects to a small/private network. Eth0 is on the inside
network of a PIX 515e and has internet access. Here's a simple pic:

internet --- PIX --- (192.168.9.0/24) --- Ubuntu --- (192.168.8.0/24)

The PIX is the default gateway for ubuntu eth0 as well as all the host on
the .9 network. I have added a route on the PIX to send traffic from the .9
network to the IP of the ubuntu box. From the PIX I can ping eth1 of the
ubuntu box, but not a device on that .8 network.

I've enable routing on the ubuntu box (ip_forward is set to 1).

No other boxes on the .9 network can even ping eth1 on the ubuntu box.

What in the world am I missing here? I've done several google searches and
all of them point to enabling ip_forward and make sure iptables is not
blocking anything. IP tables is currently off on the ubuntu box.

Anyone have any ideas?

Thanks,
Brian