I'd like to know the safest way to load iptables using Debian. Of course, I can use a script that uses iptables-restore :

#!/bin/sh
iptables-restore < /etc/firewall.conf

but : 1) where is the safest place to have it loaded ? /etc/network/if-up.d ? I'm concerned about the script being loaded early enough at boot time, and reliably enough when plugging/unplugging interfaces ...

2) is this script method using iptables-restore the most secure way ?

3) additionnally, how much does the answer validity stretch to other Linux distros ( Ubuntu, Fedora, CentOS ) ?

Thanks ^^