Requirements for fwctrl to work:

- Netfilter needs to be enabled in Linux kernel and IPTables firewall needs to be installed
- The user that runs the commands must have access to iptables-save and iptables-restore:
    $ chmod u+s /sbin/iptables-save
    $ chmod u+s /sbin/iptables-restore
- For some reason iptables-save doesn't work if iptables itself was never run.
    $ iptables -L (as root)