I started reading this book
http://www.amazon.com/gp/product/0321194438/sr=8-6/qid=1153240615/ref=sr_1_6/002-0766688-0380035?ie=UTF8
and in the firewall chapter the author gives you a sample iptables script to start with for a firewall, it's something like this:
#! /bin/bash
#flush any existing rules
iptables -F FORWARD
iptables -F INPUT
iptables -F OUTPUT
#drop all traffic
iptables -P FORWARD DROP
iptables -A INPUT DROP
#accept fragmented packets
iptables -A FORWARD -f -j ACCEPT
#accept http traffic from pre-existing connections
iptables -A FORWARD -p tcp -i eth0 -d 192.168.0.0/24 --dport 80 --tcp-flags SYN,ACK SYN,ACK -j ACCEPT
iptables -A FORWARD -p tcp -i eth0 -d 192.168.0.0/24 --sport 80 --tcp-flags SYN,ACK SYN,ACK -j ACCEPT
#allow outgoing http connections
iptables -A FORWARD -m multiport -p tcp -i eth0 -d 0.0.0.0 --dport 80 --syn -j ACCEPT
#allow incoming udp for dns resolution and allow outbound connections
iptables -A FORWARD -m multiport -p udp -i eth0 -d 192.168.0.0/24 --dport 53 -j ACCEPT
iptables -A FORWARD -m multiport -p udp -i eth0 -d 192.168.0.0/24 --sport 53 -j ACCEPT
iptables -A FORWARD -m multiport -p udp -i eth0 -d 0.0.0.0 --dport 53 -j ACCEPT
iptables -A FORWARD -m multiport -p udp -i eth0 -d 0.0.0.0 --sport 53 -j ACCEPT
Does this seem correct to anyone? All other info I've read suggests putting your deny rules and the end or else nothing will get through. I realize iptables is a complex tool and things can be accomplish in different ways but is this just totally wrong or what?
