Persistent firewall in Ubuntu

Use of normal iptables command in Ubuntu would cause firewall rules to not persist after reboot. For persistent firewall rules in Ubuntu use:

sudo apt-get update
sudo apt-get install iptables-persistent
Then to save current firewall rules to persist after reboot use:
```
sudo invoke-rc.d iptables-persistent save
```
The persistent files are saved in /etc/iptables/rules.v4 and /etc/iptables/rules.v6

Refer:

Anonymous