Firewall Iptables CentOS 6.x (Script de inicio)

firewall_rules_start.sh

#!/bin/bash

# Open port 53 on firewall (iptables) Only for CentOS 6.X
sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
sudo iptables -A INPUT -p icmp -j ACCEPT # (Ping)
sudo iptables -A INPUT -i lo -j ACCEPT # (localhost)

sudo iptables -A INPUT -p tcp --dport ssh -j ACCEPT # SSH-Acceso

sudo iptables -I INPUT -p tcp -m tcp --dport 53 -j ACCEPT # DNS
sudo iptables -I INPUT -p udp -m udp --dport 53 -j ACCEPT # DNS

iptables -A INPUT -m state --state NEW -p tcp --dport 53 -j ACCEPT # DNS
iptables -A INPUT -m state --state NEW -p udp --dport 53 -j ACCEPT # DNS

sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT # httpd24-httpd (Apache Web)
sudo iptables -A INPUT -p tcp --dport 3306 -j ACCEPT # MySQL

sudo iptables -P INPUT DROP # DROP ALL

sudo service iptables save # guardamos las reglas