You can adjust how administrators will be able to "shadow" a Terminal Services session. You can restrict a user to viewing a session only, or allow him to have full control of the keyboard and mouse. To adjust these settings through Terminal Services Configuration, follow these steps:
Open the Terminal Services Configuration applet within Server Manager.
In the middle pane, select the applicable connection, right-click it, and choose Properties.
Navigate to the Remote Control tab.
Click "Use Remote Control with the Following Settings" to configure remote control for the connection. Or, to disallow remote control, click Do Not Allow Remote Control.
To display a message on the client asking permission to view or take part in the session, check the "Require user's permission" checkbox.
Under "Level of Control," click "View the Session" to specify that the user's session can be viewed only, or click "Interact with the Session" to specify that the user's session can be actively controlled with your keyboard and mouse.
Click OK to complete the procedure.