If you are trying to make iptables survive a reboot in Debian Squeeze or Wheezy, you may find the following of use. After you get your iptables all squared away, save them to a text file with the incredibly handy /sbin/iptables-save command:
/sbin/iptables-save > /root/iptables.saved
This will create a text file in the /root directory containing lines that will be parsed by iptables when used with the iptables-restore command.
Next, add the following script to your system: