#!/bin/bash
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT

# Gotta allow loop back
iptables -A INPUT -i lo -j ACCEPT

# Allow related or established connections
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# Allow desited ports
iptables -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT

# Deny SYN,ACK bullshit
iptables -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j DROP
iptables -A INPUT -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j DROP
iptables -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG FIN,SYN,RST,PSH,ACK,URG -j DROP
iptables -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP

# Deny Reserved Address ranges that may be spoofed
iptables -A INPUT -s 0.0.0.0/8 -i venet0:0 -j DROP
iptables -A INPUT -s 127.0.0.0/8 -i venet0:0 -j DROP
iptables -A INPUT -s 10.0.0.0/8 -i venet0:0 -j DROP
iptables -A INPUT -s 172.16.0.0/12 -i venet0:0 -j DROP
iptables -A INPUT -s 192.168.0.0/16 -i venet0:0 -j DROP
iptables -A INPUT -s 224.0.0.0/3 -i venet0:0 -j DROP

# Drop all udp traffic
iptables -A INPUT -p udp -j DROP

# Doesnt match any rules above, drop by default
iptables -A INPUT -f -j DROP

# Deny pings
iptables -A OUTPUT -p icmp -m icmp --icmp-type any -j DROP