Implement nat forwarding

FORWARD.tcp

@@ -0,0 +1,2 @@
+#dest-ip public-port private-port
+192.168.1.105 2222 22

FORWARD.udp

@@ -0,0 +1 @@
+#dest-ip public-port private-port

e-router

@@ -59,6 +59,24 @@ setup_nat() {
 setup_forward() {
     iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
     iptables -A FORWARD -i ${eth0} -o ${wan} -j ACCEPT
+    while read -r ip public private ; do
+        [[ "$ip" =~ ^[0-9]{1,}.[0-9]{1,}.[0-9]{1,}.[0-9]{1,}$ ]] || continue
+        [[ "$public" =~ ^[0-9]{1,}$ ]] || continue
+        [[ "$private" =~ ^[0-9]{1,}$ ]] || continue
+        iptables -A PREROUTING -t nat -i ${wan} -p tcp --dport ${public} -j DNAT --to ${ip}:${private}
+        #iptables -A FORWARD -i ${wan} -p tcp --syn --dport ${private} -m conntrack --ctstate NEW --ctproto TCP -j ACCEPT
+        iptables -A FORWARD -i ${wan} -p tcp --syn -d ${ip} --dport ${private} -m conntrack --ctstate NEW --ctproto TCP -j ACCEPT
+    done < $confd/FORWARD.tcp
+
+    while read -r ip public private ; do
+        [[ "$ip" =~ ^[0-9]{1,}.[0-9]{1,}.[0-9]{1,}.[0-9]{1,}$ ]] || continue
+        [[ "$public" =~ ^[0-9]{1,}$ ]] || continue
+        [[ "$private" =~ ^[0-9]{1,}$ ]] || continue
+        iptables -A PREROUTING -t nat -i ${wan} -p udp --dport ${public} -j DNAT --to ${ip}:${private}
+        #iptables -A FORWARD -i ${wan} -p udp --dport ${private} -m conntrack --ctstate NEW --ctproto UDP -j ACCEPT
+        iptables -A FORWARD -i ${wan} -p udp -d ${ip} --dport ${private} -m conntrack --ctstate NEW --ctproto UDP -j ACCEPT
+    done < $confd/FORWARD.udp
+
     if $logforward ; then
         setup_fordroplog
         iptables -A FORWARD -j FORWARD-LOG-DROP