$IPT -F
$IPT -X
$IPT -A INPUT -m state --state ESTABLISHED -j ACCEPT #do not block any outgoing connection from this server

$IPT -t nat -A POSTROUTING -o WAN -j MASQUERADE

$IPT -I INPUT -i WAN -p tcp --dport 80 -j ACCEPT #http
$IPT -I INPUT -i WAN -p tcp --dport 81 -j ACCEPT #lsws admin
$IPT -I INPUT -i WAN -p tcp --dport 22 -j ACCEPT #ssh
$IPT -I INPUT -i WAN -p tcp --dport 3306 -j ACCEPT #mysql

#Fwd some ports for VoIP
$IPT -I FORWARD -s 11.12.13.99 -p tcp --dport 5060 -j ACCEPT
$IPT -A PREROUTING -t nat -i WAN -p tcp -m tcp --dport 5060 -j DNAT --to-destination 11.12.13.99 #SIP
$IPT -A PREROUTING -t nat -i WAN -p udp -m udp --dport 5060 -j DNAT --to-destination 11.12.13.99 #SIP

$IPT -I FORWARD -s 11.12.13.99 -p udp --dport 10000:20000 -j ACCEPT #RTP
$IPT -A PREROUTING -t nat -i WAN -p udp --dport 10000:20000 -j DNAT --to-destination 11.12.13.99 #RTP