#!/bin/bash

# Setup very restrictive eth1 firewall for Mess Office
# Allow mess office through internet chain so that doesn't get dropped later
$IPTABLES -t nat -I internet -i eth1 -j ACCEPT
# The following rules allow a restricted set of protocols
# Allow DNS lookups
$IPTABLES -A INPUT -i eth1 -m udp -p udp --dport 53 -j ACCEPT
$IPTABLES -A OUTPUT -o eth1 -m udp -p udp --sport 53 -j ACCEPT
# Accept port 80 traffic (HTTP)
$IPTABLES -A FORWARD -i eth1 -o ppp0 -p tcp --dport 80 -j ACCEPT
$IPTABLES -A FORWARD -i ppp0 -o eth1 -p tcp --sport 80 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Accept port 443 traffic (HTTPS)
$IPTABLES -A FORWARD -i eth1 -o ppp0 -p tcp --dport 443 -j ACCEPT
$IPTABLES -A FORWARD -i ppp0 -o eth1 -p tcp --sport 443 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Accept 993 (secure server email)
$IPTABLES -A FORWARD -i eth1 -o ppp0 -p tcp --dport 993 -j ACCEPT
$IPTABLES -A FORWARD -i ppp0 -o eth1 -p tcp --sport 993 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Accept SSH
$IPTABLES -A INPUT -i eth1 -p tcp --dport 22 -j ACCEPT
$IPTABLES -A OUTPUT -o eth1 -p tcp --sport 22 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Allow port 25 (SMTP)
$IPTABLES -A INPUT -i eth1 -p tcp --dport 25 -j ACCEPT
$IPTABLES -A OUTPUT -o eth1 -p tcp --sport 25 -m state --state ESTABLISHED,RELATED -j ACCEPT
# Allow all ICMP traffic
$IPTABLES -A INPUT -i eth1 -p icmp -j ACCEPT
$IPTABLES -A FORWARD -i eth1 -p icmp -j ACCEPT
$IPTABLES -A FORWARD -o eth1 -p icmp -j ACCEPT
$IPTABLES -A OUTPUT -o eth1 -p icmp -j ACCEPT
# Log all dropped internet traffic
#$IPTABLES -A INPUT -i eth1 -j LOG
# Drop all local traffic
$IPTABLES -A INPUT -i eth1 -j DROP
$IPTABLES -A OUTPUT -o eth1 -j DROP
# All other forwarded traffic is dropped by default