iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -m comment --comment "Already approved traffic"
iptables -A INPUT -p tcp -i eth0 -m state --state NEW -s 0.0.0.0/0 -m multiport --dports 22,80,443 -j ACCEPT -m comment --comment "Let in the good stuff"
iptables -A INPUT -j DROP
iptables-save > /etc/iptables.rules
vi /etc/network/if-pre-up.d/iptables