#! /bin/bash

IPT="/sbin/iptables"


#Flush all rules and remove chains

$IPT -F
$IPT -X

#Block access by default

$IPT -P INPUT DROP
$IPT -P FORWARD DROP
$IPT -P OUTPUT DROP

#List of ports

TCP_PORTS="47,1723,2121"

#Allow packets for loopback interface

$IPT -A INPUT -i lo -j ACCEPT
$IPT -A OUTPUT -o lo -j ACCEPT

#Allow packets for established connection

$IPT -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

#Allow packets for outgoing connections

#$IPT -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$IPT -A OUTPUT -j ACCEPT

#Allow ports
$IPT -A INPUT -p tcp -m multiport --dport $TCP_PORTS -j ACCEPT
$IPT -A INPUT -i eth0 -p gre -j ACCEPT
$IPT -t nat -A POSTROUTING -o eth0 -j MASQUERADE

#Allow outgoing ping
$IPT -A INPUT -p icmp -m icmp --icmp-type echo-reply -j ACCEPT