If you want your iptables rules automatically loaded every time your networking comes up on your Debian or Ubuntu server, you can follow these easy steps.
// First save your firewall rules
iptables-save > /etc/iptables/iptables.rules
// Edit startup file at
nano /etc/network/if-up.d/iptables
// Fill in the correct iptables path
#!/bin/sh
iptables-restore < /etc/iptables/iptables.rulesNow, the rules will be restored each time your networking scripts start (or restart).