gistfile1.txt

#!/bin/bash
#Clear old iptables and nat rules  (flush)
 iptables -F
 iptables -t nat -F

#Create Input, Output, and Forward Chains
 iptables -P INPUT ACCEPT
 iptables -P OUTPUT ACCEPT
 iptables -P FORWARD DROP

#Set variables for the local interfaces
 export LAN=eth1
 export WAN=eth0

#Accept traffic from the LAN/WAN and Loopback interface
 iptables -I INPUT 1 -i ${LAN} -j ACCEPT
 iptables -I INPUT 1 -i ${WAN} -j ACCEPT
 iptables -I INPUT 1 -i lo -j ACCEPT

#NAT RULES
iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE
iptables -A FORWARD -i ${WAN} -o ${LAN} -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i ${LAN} -o ${WAN} -j ACCEPT

# Forward port 8888 on WAN to port 80 on 192.168.
iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j DNAT --to 192.168.56.101:8080
iptables -A FORWARD -p tcp -d 192.168.56.101 --dport 8080 -j ACCEPT

#Enable Forwarding
 echo 1 > /proc/sys/net/ipv4/ip_forward
 for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done

#Save the rules so this script doesn't have to be ran each time 
 /etc/init.d/iptables save