PC-BSD uses OpenBSD's PF (Packet Filter) tool to filter incoming and outgoing traffic through network interfaces. Configuring the firewall requires learning the basics of PF. To change the rules of your firewall, you need to edit the configuration file of the firewall. In your terminal, issue the following command:
$ kdesu kwrite /etc/rc.d/pf_rules
At the prompt, type your root password. A text editor will display the firewall configuration file. Make your changes and save. Reboot PC-BSD. PF should use your new set of rules.