D-Link DSL-6740U User Manual page 55

Section 3 - Configuration
Select a name from the Select a Service drop-down menu for a
pre-configured application or type a name in the Custom Server
input box to define your own application.
Type an IP address in the Server IP address input box to appoint
the PC to receive the forwarded packets.
The External Port shows the ports opened for remote users in
the WAN side of the router. The TCP/UDP means the protocol
type of the opened ports.
The Internal Port shows the ports opened in the PC with the
appointed IP Address. The TCP/UDP means the protocol type of
the opened ports.
D-Link DSL-6740U User Manual 55