#!/bin/bash
#
# LEARNING IPTABLES SCRIPT
#
## Variables ##
EXTERNAL_NET="eth0"
DMZ_NET="eth1"
INTERNAL_NET="eth2"
#
INTERNAL="192.168.1.0/24"
DMZ="172.16.1.0/24"
EXTERNAL="192.168.2.0/24"
#
## Acquiring the ip address for the devices ##
INT_IP=`ifconfig $INTERNAL_NET | grep "inet addr" | cut -d ":" -f 2 | cut -d " " -f 1`
DMZ_IP=`ifconfig $DMZ_NET | grep "inet addr" | cut -d ":" -f 2 | cut -d " " -f 1`
EXT_IP=`ifconfig $EXTERNAL_NET | grep "inet addr" | cut -d ":" -f 2 | cut -d " " -f 1`

## Flush the chains ##
iptables -F
iptables -F INPUT
iptables -F OUTPUT
iptables -F FORWARD
#
## Setting policies
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
#
## Enable routing ##
echo "1" > /proc/sys/net/ipv4/ip_forward
#
## Logging ##
LOG_LEVEL="notice"
#
## FORWARD traffic between INTERNAL and DMZ
iptables -A FORWARD -i $INTERNAL_NET -o $DMZ_NET -j ACCEPT
iptables -A FORWARD -i $DMZ_NET -o $INTERNAL_NET -j ACCEPT
#