By default Windows Remote
Desktop listens for connection on port 3389. Two valid reasons for wanting to
change this number are for security concerns and/or multiple RDP network
configurations.
Why not use 3389?
Security Concern:
Using simple network ping sweeping software can pull your external IP up as one that has the default port 3389 open. Intruding into your network could be as easy as entering in the logon password.
RDP configurations:
Say you have three computers behind a firewalled router and you want all three to be accessible via RDP. This is only possible by changing the default port on at least two out of three of the machines.
