iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP

iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT

iptables -A INPUT -i eth0 -p tcp -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

iptables -A INPUT -i eth0 -p tcp -m multiport --sports 22,80,443 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp -m multiport --dports 22,53,80,443 -m conntrack —ctstate NEW,ESTABLISHED -j ACCEPT

iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP