-$IPT -t filter -A INPUT -m state --state INVALID -j DROP
-$IPT -t filter -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-$IPT -t filter -A INPUT -p icmp -j ACCEPT
-$IPT -t filter -A INPUT -p 47 -j ACCEPT # allow GRE
-$IPT -t filter -A INPUT -i $WAN -p tcp -j REJECT --reject-with tcp-reset
-$IPT -t filter -A INPUT -i $WAN -j REJECT --reject-with icmp-port-unreachable
-$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
+iptables -N input_rule
+iptables -N output_rule
+iptables -N forwarding_rule
+
+iptables -t nat -N prerouting_rule
+iptables -t nat -N postrouting_rule
+
+### Allow SSH from WAN
+# iptables -t nat -A prerouting_rule -i $WAN -p tcp --dport 22 -j ACCEPT
+# iptables -A input_rule -i $WAN -p tcp --dport 22 -j ACCEPT
+
+### Port forwarding
+# iptables -t nat -A prerouting_rule -i $WAN -p tcp --dport 22 -j DNAT --to 192.168.1.2
+# iptables -A forwarding_rule -i $WAN -p tcp --dport 22 -d 192.168.1.2 -j ACCEPT
+
+### DMZ (should be placed after port forwarding / accept rules)
+# iptables -t nat -A prerouting_rule -i $WAN -j DNAT --to 192.168.1.2
+# iptables -A forwarding_rule -i $WAN -d 192.168.1.2 -j ACCEPT
+
+### INPUT
+### (connections with the router as destination)
+
+ # base case
+ iptables -P INPUT DROP
+ iptables -A INPUT -m state --state INVALID -j DROP
+ iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
+ iptables -A INPUT -p tcp --syn --tcp-option \! 2 -j DROP
+
+ # allow
+ 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
+ #
+ # insert accept rule or to jump to new accept-check table here
+ #
+ iptables -A INPUT -j input_rule
+
+ # reject (what to do with anything not allowed earlier)
+ iptables -A INPUT -p tcp -j REJECT --reject-with tcp-reset
+ iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable
+
+### OUTPUT
+### (connections with the router as source)
+
+ # base case
+ iptables -P OUTPUT DROP
+ iptables -A OUTPUT -m state --state INVALID -j DROP
+ iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
+
+ # allow
+ iptables -A OUTPUT -j ACCEPT #allow everything out
+ #
+ # insert accept rule or to jump to new accept-check table here
+ #
+ iptables -A OUTPUT -j output_rule
+
+ # reject (what to do with anything not allowed earlier)
+ iptables -A OUTPUT -p tcp -j REJECT --reject-with tcp-reset
+ iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable
+
+### FORWARDING
+### (connections routed through the router)
+
+ # base case
+ iptables -P FORWARD DROP
+ iptables -A FORWARD -m state --state INVALID -j DROP
+ iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
+ iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
+
+ # allow
+ iptables -A FORWARD -i br0 -o br0 -j ACCEPT
+ iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT
+ #
+ # insert accept rule or to jump to new accept-check table here
+ #
+ iptables -A FORWARD -j forwarding_rule
+
+ # reject (what to do with anything not allowed earlier)
+ # uses the default -P DROP
+
+### MASQ
+ iptables -t nat -A PREROUTING -j prerouting_rule
+ iptables -t nat -A POSTROUTING -j postrouting_rule
+ iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE