port forwarding

#!/bin/bash -xIPFRDCTL=/proc/sys/net/ipv4/ip_forwardWANNIC=eth1#LANNIC=tun0LANNIC=eth0if [[ -f "${IPFRDCTL}" ]]	then	echo 1 > "${IPFRDCTL}"	else	echo "need ip_forward in kernel"	exit 0fiDAEMON=iptables	${DAEMON} -F	${DAEMON} -I INPUT -i ${LANNIC} -j ACCEPT	${DAEMON} -I INPUT -i ${WANNIC} -p tcp --dport 22 -j ACCEPT	${DAEMON} -I INPUT -i ${WANNIC} -p tcp --dport 5000 -j ACCEPT	${DAEMON} -I INPUT -i ${WANNIC} -p all -m state --state RELATED,ESTABLISHED -j ACCEPT	${DAEMON} -t nat -A POSTROUTING -o ${WANNIC} -j MASQUERADE	${DAEMON} -A FORWARD -i ${WANNIC} -o ${LANNIC} -m state --state RELATED,ESTABLISHED -j ACCEPT	${DAEMON} -A FORWARD -i ${LANNIC} -o ${WANNIC} -j ACCEPT	${DAEMON} -A FORWARD -i ${WANNIC} -o ${LANNIC} -j DROP	#${DAEMON} -A INPUT -i ${WANNIC} -p tcp --dport ! 22 -j DROPecho "NAT from private:${LANNIC} to public:${WANNIC}"