I am trying to setup ip masquerading on my home network but am having some troubles!

My first machine (router) has two interfaces eth0,eth1. eth0 is on the internet, eth1 internal. I have tried to setup masquerading with the following rules.

iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

I have setup up another machine with this machine as it's gateway and tried to ping a server. I get:

Redirect Host(New nexthop: 10.255.255.254)
Destination Host unreachable

The routers IP is 10.116.0.1 (internal) which makes me wonder about the ip given for nexthop.

Sorry if this is messy or doesn't make much sense but i'm writing this using lynx on a console (due to this problem!)

Any help would be greatly appreciated!
Chris

What is the total output for 'ifconfig' on both machines?

or better yet, what does /etc/sysconfig/network-scripts/ifcfg-eth0 and /etc/sysconfig/network-scripts/ifcfg-eth1 show on both machines?

What does 'route' show on both machines?

I have looked at the output of route on the router machine and it appears that the IP address given for nexthop is the default gateway for eth1 (the internal interface).

Within 'ifcfg-eth1' no gateway is set up. Does this need to be done?

To my mind this seems to mean that iptables is trying to pass the masqueraded packets through the wrong interface, even though the '-o' option is set to eth0 (external interface).

Any idea why?

Cheers,

Chris

Here is how I usually set it up:

I configure the external NIC with the gateway and IP addy that my ISP provides. I configure the internal NIC with an internal IP but I use the external NIC as the gateway. All of that shows up in the ifcfg-eth? scripts.

I make sure that I have ip_forward on and I set the MASQ up in IPCHAINS. Restart your network after doing all that and you shouuld be good to go.

The routing should be set up correctly automatically once you get the other IP info correct for each NIC.

Thanks for your help kevin. It turned out in the end to be a spurious entry in /etc/sysconfig/network. I believe this was caused by the use of the 'netconfig' program. I had originally configured everything by hand, and when it didn't work I used this program! Guess that'll teach me for trying to do things the quick way!!!!

Cheers,

Chris