$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 -o $WAN -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
$IPT -t nat -A POSTROUTING -o $WAN -j MASQUERADE