$IPT -t filter -A FORWARD -m state --state INVALID -j DROP
$IPT -t filter -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
$IPT -t filter -A FORWARD -i $WAN -m state --state NEW,INVALID -j DROP
$IPT -t filter -A FORWARD -m state --state INVALID -j DROP
$IPT -t filter -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
$IPT -t filter -A FORWARD -i $WAN -m state --state NEW,INVALID -j DROP