iptables -A PREROUTING  -p tcp -m tcp -d <yours_wan_ip> --dport 8001 -j DNAT --to-destination 192.168.1.200:8080

iptables -A FORWARD -m state -p tcp -d 192.168.1.200 --dport 8080 --state NEW,ESTABLISHED,RELATED -j ACCEPT

iptables -A POSTROUTING -p tcp -m tcp -s 192.168.1.200 --sport 8080 -j SNAT --to-source <yours_wan_ip>