- iptables -A INPUT -i \! $WAN -j ACCEPT # allow from lan/wifi interfaces
- iptables -A INPUT -p icmp -j ACCEPT # allow ICMP
- iptables -A INPUT -p 47 -j ACCEPT # allow GRE
- iptables -A INPUT -p tcp --syn --tcp-option \! 2 -j DROP
+ iptables -A INPUT -i \! $WAN -j ACCEPT # allow from lan/wifi interfaces
+ iptables -A INPUT -p icmp -j ACCEPT # allow ICMP
+ iptables -A INPUT -p gre -j ACCEPT # allow GRE