Starting from Terminal Service Plus version 6.60, you can block/disable any attempt to connect using mstsc.exe (or any RDP clients) over the open/redirected port (80 or 443).

This feature only allows accesses from the Terminal Service Plus Web Portal and disables any other RDP connection on port 80/443.

To activate this feature on a server, edit the file C:\Program Files (x86)\TSplus\UserDesktop\files\AppControl.ini and add/modify the following variable:

[Security]
Block_rdp_splitter=yes