Basic iptables config

README

https://help.ubuntu.com/community/IptablesHowTo

Place the scripts in 
/etc/network/if-pre-up.d and /etc/network/if-post-down.d

iptables.rules

*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
[0:0] -A INPUT -i lo -j ACCEPT 
[0:0] -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT 
[0:0] -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT 
[0:0] -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT 
[0:0] -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT 
[0:0] -A INPUT -j DROP 
COMMIT

iptablesload

#!/bin/sh
iptables-restore < /etc/iptables.rules
exit 0

iptablessave

#!/bin/sh
iptables-save -c > /etc/iptables.rules
exit 0