The UFW application is not the firewall but an interface to simplify creation of the iptables firewall, There are various other applications that you can use to build your firewall including doing it directly from the command line and scripts. You can find more about the various option my searching the software center for firewall of searching google for "linux firewall software" http://lmgtfy.com/?q=linux+firewall+software . My personal preference is to build shell script to control iptables directly.