I have iptables acting as a NAT gateway for a home LAN on a single cable connection. A gateway script is run from the /etc/rc.d/init.d/iptables script that sets up the iptables rules that i need.

I think for some reason or another the rules applied by the gateway script are being flushed soon after they're applied. This only happens during startup though, so I'm guessing something else run afterwards is flushing the iptables rules.

I can manually run /etc/rc.d/init.d/iptables or even just the gateway script /etc/iptables/eth1-gateway.sh and everything works as I expect it to.

I know that the script is being run because I put a line in the gateway script /etc/iptables/eth1-gateway.sh that creates a file in my home directory. This file is created every time with the correect contents so I know the line (and therefore the gateway script) are being run at startup.

Anyone have any idea why this is happening?

If RedHat, do you have Lokkit installed?

1. Run your iptables scripts.
2. iptables -L ==> will show the current rules
3. repeat until they get flushed.
4. look at the cron log to see a list of suspects.
Of course, the following could be placed in cron.
* * * * * /sbin/iptables -L >> /tmp/iptables.tmp.log
It'll grow rapidly, so don't leave it running too long!