Rules, Interfaces, and DHCP

All PF rules are set at the time the rules are parsed. This can be a problem if you're using DHCP or PPP, where your IP address will change frequently enough to cause annoyance. Your computer may be up for some time and change IP addresses several times. By putting the interface name in parentheses, you tell PF to adjust the rules whenever the IP address changes.

 block in on (fxp0) from any to any