IPTables rules being applied multiple times at startup

Question

Specifically talking about an Ubuntu 10.04 LTS server (Lucid Lynx), although its probably applicable to other Linux versions.

I was trawling through the logs for a few websites, doing some spring cleaning so to speak and noticed a few IP addresses that have been acting dodgy so I wanted to add them to the blacklist.

Basically I got playing around with IPtables, the blacklist of IP's is just a text file. I then created a shell script to loop through the text file and block each IP address in IPtables.

This worked fine when the shell script was run manually. But obviously I wanted it to run automatically at start up, for whenever the server may be rebooted. So I included the shell script into

Code:

/etc/network/if-pre-up.d/iptables

So it now looks like

Code:

#!/bin/sh 
/sbin/iptables-restore < /etc/iptables.up.rules
sh /etc/addBlacklist.sh

So I rebooted the server and the blacklist rules where applied, but it seems like they have been applied multiple times. As in duplicate lines appearing when iptables -L is run.

Just wondering if anyone would know the reason for this?

I suppose it doesn't really matter in the grand scheme of things but I'm curious.

Answer 1

Never did find out why they where being applied multiple times but I just removed the separate blacklist file and amalgamated it into the iptables.up.rules file.

Not as pretty but stops the duplication.

Answer 2

Just add the iptables -F at the start of the script so when the script starts, it automatically flushes the old entry and then blocks the ip's again.