#!/bin/sh

ipfw -q -f flush

cmd="ipfw -q add"
nic="em0"

$cmd 00010 pass all from any to any via lo0

$cmd 00011 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions mss,window,sack,ts \
  tcpwin 1
$cmd 00012 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions mss,window,sack,ts \
  tcpwin 63
$cmd 00013 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions mss,window,ts \
  tcpwin 4
$cmd 00014 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions window,sack,ts \
  tcpwin 4
$cmd 00015 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions mss,window,sack,ts \
  tcpwin 16
$cmd 00016 drop log ip4 from any to any in via $nic \
  tcpdatalen 0 \
  tcpflags syn,!fin,!rst,!psh,!ack,!urg \
  tcpoptions mss,sack,ts \
  tcpwin 512

$cmd 00020 pass  all from any to any via $nic