rc.conf
firewall_enable="YES"
firewall_script="/etc/ipfw.rules"
/etc/ipfw.rules
#!/bin/sh
# Flush out the list before we begin.
ipfw -q -f flush
# Set rules command prefix
wan="re0"
lan="re1"
# Change xl0 to LAN NIC interface name
ipfw -q add 00005 allow all from any to any via $lan
ipfw -q add 00005 allow all from any to any via $wan
# No restrictions on Loopback Interface
ipfw -q add 00010 allow all from any to any via lo0
ipfw -q add 00101 check-state
ipfw -q add 00102 allow tcp from any to any established
ipfw -q add 00102 allow tcp from any to any established
ipfw -q add 00103 allow icmp from any to any
links