iptables

iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -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 -i lo -j ACCEPT &&
iptables -D INPUT -p tcp -m tcp --dport 21 -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --dport 443 -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --dport 1989 -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --dport 1500 -j ACCEPT &&
iptables -A INPUT -p tcp -m tcp --dport 18080 -j ACCEPT &&
iptables -A INPUT -j DROP

from http://hosterlab.net

iptables-save > /etc/iptables.up.rules
vim /etc/network/if-up.d/iptables

``

!/bin/sh

/sbin/iptables-restore < /etc/iptables.up.rules
``

chmod +x /etc/network/if-up.d/iptables

iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
allow PING