Single WAN with multiple port to different LAN internal IPs

Hi guys, 

I’m trying to NAT (or DNAT) Single WAN with multiple ports to Internal LAN IPs. Just wondering what’s the best way to do it.

Example:

WAN 40.12.34.56:1000 to 192.168.1.5

WAN 40.12.34.56:2000 to 192.168.1.6

WAN 40.12.34.56:3000 to 192.168.1.7