Ubuntu – reload iptables rules during boot

Steps to load iptable rules automatically on Ubuntu Linux using package iptables-persistent.

1. Install iptables-persistent

   $ sudo apt-get install iptables-persistent
   

2. When asked during installation should it save current iptables to /etc/iptables/rules.v4 and /etc/iptables/rules.v6, enter yes.
   

3. In case you make any changes to iptables, run the following to persist these. Note that rules won’t get persisted automatically.

   $ sudo /etc/init.d/iptables-persistent save 
   

4. Do a diff of changes made to ip tables with persisted values in /etc/iptables/rules.v4

   $ sudo iptables-save > unsaved_rules
   $ diff unsaved_rules /etc/iptables/rules.v4
   

   Similarly we can diff v6 rules using ip6tables-save

5. To reload iptables rules (v4 and v6 both) using /etc/init.d/iptables-persistent

   $ sudo /etc/init.d/iptables-persistent reload
   

   Note that this will override current loaded rules in iptables.

6. On reboot /etc/init.d/iptables-persistent will load saved rules automatically.