P18 --Forwarding a port to an internal IP using Mikrotik

This example will show you how to forward port (tcp 5900) to an internal IP using destination NAT. 69.69.69.69 is the example wan IP, 192.168.1.101 is the desired internal destination.

/ip firewall nat add chain=dstnat dst-address=69.69.69.69 protocol=tcp dst-port=5900 \
    action=dst-nat to-addresses=192.168.1.101 to-ports=5900