Need to know the RDP port number to open on your firewall? You’ll need to open up TCP 3389 to enable RDP or Remote Desktop services to pass through a firewall. By default most firewalls block the RDP port 3389 so if you are trying to RDP to a workstation or server on the other side of a firewall, make sure that the RDP port TCP 3389 is open.
If you want to start Remote Desktop from a command line or run prompt you want to use the Remote Desktop Command MSTSC or MSTSC.EXE which starts the Microsoft Remote Desktop client. You can find the remote desktop client under the accessories folder in all programs however it is much faster to start Remote Desktop with the command mstsc. I just click start and if on Windows XP I type mstsc and hit enter or ok. On Windows Vista or Windows 7 you just click the start button and type mstsc in the run blank and hit enter to start Remote Desktop.
The firewall port used by the Remote Desktop service is TCP 3389 otherwise known as the RDP port. Most firewalls including personal firewalls used in Windows and by third party applications block TCP 3389 by default. So to get Remote Desktop working through firewalls you or your firewall administrator will need open port TCP 3389.
If you want to use Remote Desktop to connect to a server or Windows PC you may need to open a port in your router or firewall to get it to work. The port to open that allows the use of Remote Desktop is port TCP 3389 also known as RDP or the RDP Protocol. You may also need to alter the settings on your Windows firewall or other personal firewall to allow TCP 3389 to pass through.