iptables -t nat -A PREROUTING -i eth0 -p tcp -m tcp --dport 8080 -j DNAT --to-destination 216.34.181.45:80
to see port inside of your LAN remove -i eth0 and it will be for all Lan connections.
Redirect just Ports
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-ports 8080