#!/bin/bash
#First we flush our current rules
iptables -F
iptables -t nat -F

#Setup default policies to handle unmatched traffic
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD DROP

export LAN=venet0
#export LAN=pdummy0
#export LAN=vif1.0
#export LAN=dummy0
export WAN=eth0

#Then we lock our services so they only work from the LAN
iptables -I INPUT 1 -i ${LAN} -j ACCEPT
iptables -I INPUT 1 -i lo -j ACCEPT
iptables -A INPUT -p UDP --dport bootps -i ! ${LAN} -j REJECT
iptables -A INPUT -p UDP --dport domain -i ! ${LAN} -j REJECT

#(Optional) Allow access to our ssh server from the WAN
iptables -A INPUT -p TCP --dport ssh -i ${WAN} -j ACCEPT
#Allow access to our vmware server from the WAN
iptables -A INPUT -p TCP --dport 902 -i ${WAN} -j ACCEPT
iptables -A INPUT -p TCP --dport 903 -i ${WAN} -j ACCEPT

#Drop TCP / UDP packets to privileged ports
iptables -A INPUT -p TCP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP
iptables -A INPUT -p UDP -i ! ${LAN} -d 0/0 --dport 0:1023 -j DROP

#Finally we add the rules for NAT
iptables -I FORWARD -i ${LAN} -d 192.168.2.0/255.255.255.0 -j DROP
iptables -A FORWARD -i ${LAN} -s 192.168.2.0/255.255.255.0 -j ACCEPT
iptables -A FORWARD -i ${WAN} -d 192.168.2.0/255.255.255.0 -j ACCEPT
iptables -t nat -A POSTROUTING -o ${WAN} -j MASQUERADE
#Tell the kernel that ip forwarding is OK
echo 1 > /proc/sys/net/ipv4/ip_forward
for f in /proc/sys/net/ipv4/conf/*/rp_filter ; do echo 1 > $f ; done

#This is so when we boot we don't have to run the rules by hand
/etc/init.d/iptables save