The following was downloaded and some changes were made, particularly in the documentation, but the basic structure is the same as contributed by Mr. Andreasson.

#!/bin/sh
#
# rc.DMZ.firewall - DMZ IP Firewall script for Linux 2.4.x
#
# Author: Oskar Andreasson <blueflux@koffein.net>
# (c) of BoingWorld.com, use at your own risk, do whatever you please with
# it as long as you don't distribute this without due credits to
# BoingWorld.com
#

###########
# Configuration options, these will speed you up getting this script to
# work with your own setup.

#
# your LAN's IP range and localhost IP. /24 means to only use the first 24 
# bits of the 32 bit IP adress. the same as netmask 255.255.255.0
#
# STATIC_IP is used by me to allow myself to do anything to myself, might
# be a security risc but sometimes I want this. If you don't have a static
# IP, I suggest not using this option at all for now but it's stil
# enabled per default and will add some really nifty security bugs for all
# those who skips reading the documentation=)

LAN_IP="192.168.0.2"
LAN_BCAST_ADRESS="192.168.0.255"
LAN_IFACE="eth1"

INET_IP="194.236.50.152"
INET_IFACE="eth0"

HTTP_IP="194.236.50.153"
DNS_IP="194.236.50.154"
DMZ_HTTP_IP="192.168.1.2"
DMZ_DNS_IP="192.168.1.3"
DMZ_IP="192.168.1.1"
DMZ_IFACE="eth2"

LO_IP="127.0.0.1"
LO_IFACE="lo"


IPTABLES="/usr/local/sbin/iptables"

###########################################
#
# Load all required IPTables modules unless compiled into the kernel
#

#
# Needed to initially load modules
#

/sbin/depmod -a

#
# Adds some iptables targets like LOG, REJECT and MASQUARADE.
#

/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_MASQUERADE

#
# Support for connection tracking of FTP and IRC.
#
#/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc


#CRITICAL:  Enable IP forwarding since it is disabled by default.
#

echo "1" > /proc/sys/net/ipv4/ip_forward

#
# Dynamic IP users:
#
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr

###########################################
#
# Chain Policies gets set up before any bad packets gets through
#

$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP

#
# the allowed chain for TCP connections, utilized in the FORWARD chain
#

$IPTABLES -N allowed
$IPTABLES -A allowed -p TCP --syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP

#
# ICMP rules, utilized in the FORWARD chain
#


$IPTABLES -N icmp_packets
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 0 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 3 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 5 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT


###########################################
# POSTROUTING chain in the nat table
#
# Enable IP SNAT for all internal networks trying to get out on the Internet
#

$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP



###########################################
# PREROUTING chain in the nat table
#
# Do some checks for obviously spoofed IP's 
#

$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 192.168.0.0/16 -j DROP
$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 10.0.0.0/8 -j DROP
$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s 172.16.0.0/12 -j DROP
$IPTABLES -t nat -A PREROUTING -i $INET_IFACE -s $INET_IP -j DROP

#
# Enable IP Destination NAT for DMZ zone
#

$IPTABLES -t nat -A PREROUTING -p TCP -i $INET_IFACE -d $HTTP_IP --dport 80 \
-j DNAT --to-destination $DMZ_HTTP_IP
$IPTABLES -t nat -A PREROUTING -p TCP -i $INET_IFACE -d $DNS_IP --dport 53 \
-j DNAT --to-destination $DMZ_DNS_IP
$IPTABLES -t nat -A PREROUTING -p UDP -i $INET_IFACE -d $DNS_IP --dport 53 \
-j DNAT --to-destination $DMZ_DNS_IP

###########################################
#
# FORWARD chain
#
# Get rid of bad TCP packets
#

$IPTABLES -A FORWARD -p tcp ! --syn -m state --state NEW -j LOG \
--log-prefix "New not syn:"
$IPTABLES -A FORWARD -p tcp ! --syn -m state --state NEW -j DROP

#
# DMZ section
#
# General rules
#

$IPTABLES -A FORWARD -i $DMZ_IFACE -o $INET_IFACE -j ACCEPT
$IPTABLES -A FORWARD -i $INET_IFACE -o $DMZ_IFACE -m state \
--state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $LAN_IFACE -o $DMZ_IFAC

&nbps