====== Ubuntu - iptables - Save IPTable rules ======

===== Save and Restore iptables =====

This will save initial copies of the firewall rules.

<code bash>
sudo iptables-save > /etc/iptables/rules.v4
sudo ip6tables-save > /etc/iptables/rules.v6
</code>

----

In **/etc/network/if-pre-up.d/iptables** enter the following:

<file bash /etc/network/if-pre-up.d/iptables>
#!/bin/sh
iptables-restore < /etc/iptables/rules.v4
ip6tables-restore < /etc/iptables/rules.v6
exit 0
</file>


In **/etc/network/if-post-down.d/iptables** enter the following:

<file bash /etc/network/if-post-down.d/iptables>
#!/bin/sh
iptables-save -c > /etc/iptables/rules.v4
if [ -f /etc/iptables/rules.v4 ]; then
  iptables-restore < /etc/iptables/rules.v4
fi
ip6tables-save -c > /etc/iptables/rules.v6
if [ -f /etc/iptables/rules.v6 ]; then
  ip6tables-restore < /etc/iptables/rules.v6
fi
exit 0
</file>

Give permission to the scripts:

<code bash>
sudo chmod +x /etc/network/if-post-down.d/iptables
sudo chmod +x /etc/network/if-pre-up.d/iptables
</code>

----

===== IPv4 vs IPv6 =====

There are slightly different commands used depending on IPv4 or IPv6.

For IPv4 the commands are **iptables-save** and **iptables-restore**.

For IPv6 the commands are **ip6tables-save** and **ip6tables-restore**.

----

===== Example Usage =====

==== Save the iptables rules ====

The generic method of saving iptables rules is to use the command **iptables-save**, which writes to stdout.

<code bash>
iptables-save > /etc/network/iptables.rules.v4
ip6tables-save > /etc/network/iptables.rules.v6
</code>

----

==== Restore the iptables rules ====

For IPv4, the output created by **iptables-save** can then by read on stdin by **iptables-restore**. Similarly, for IPv6, the output created by **ip6tables-save** can then by read on stdin by **ip6tables-restore**. 

If on a server, without NetworkManager, a common approach is then to use a **pre-up** command in /etc/network/interfaces.

<file bash /etc/network/interfaces>
iface eth0 inet static
        ....
        pre-up iptables-restore < /etc/network/iptables.rules.v4
        pre-up ip6tables-restore < /etc/network/iptables.rules.v6        
</file>