Iptables

To create persistent rules with iptables you could use the Debian/Ubuntu package: iptables-persistent

apt-get update
apt-get install iptables-persistent -y

To export and save current rules:

iptables-save > /etc/iptables/rules.v4
ip6tables-save > /etc/iptables/rules.v6

After each reboot all rules will be restored automatically through an init-script.

NB: The initscript is called: /etc/init.d/netfilter-persistent