Are 4 IPFW rules enough?

[Kevin Curran]

I have a cable modem and I'm using 4.9 as a NAT router for my home
network.  I have 4 rules in my ipfw config.  The first enables NAT and
the last is 65000 allow any to any.

In between I ha 2 rules to deny access to ports 53 and 110 on the
Internet side.  That's all.  

Here's my thinking: I use inetd.conf to enable only the services I want,
therefore the ports on which those services are listening I would want
open.  The two other ports I want to filter on the WAN side are filtered
by the rules above.  All the other ports are closed, anyway, so why
spend time debugging an elaborate rule set?