Blanking of the Host screen is now possible on Windows 10 build 2004 or newer. This feature requires PC-Duo Master v13.4 or later, Host v13.4 or later (P2P Edition or RAS Edition). If connecting to Hosts through the PC-Duo Web Console (RAS Edition) then the server should be upgraded to v13.4 or newer.
Use cases are:
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For a work-from-home user with a dedicated desktop in the office, to be able to remote control their office machine without worrying about users in the office being able to see (potentially confidential) information on the screen. This use case assumes that the people in the office who may be viewing the screen do not have rights to log into the system or access any data on the system – the risk that the Blank Screen feature addresses is that an unauthorized user sees confidential information on the screen while the computer is being used remotely.
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For an administrator or technician performing maintenance or configuration on a desktop used primarily by someone else (who presumably does not have rights/access to do that maintenance or configuration). The normal user of the machine may be at the console when this activity is going on, and if the admin/technician does not want the console user to know what was done, or see potentially sensitive information (like plain-text passwords or license keys), the Blank Screen feature can be used to hide that.
Please be aware of the following:
• The keyboard and mouse will also be suppressed while the screen is blanked. This is necessary so that a console user cannot interfere with the remote control session by using the keyboard.
• The UI for configuring Screen Blanking is on the Host Control Panel -> Options tab and allows you to set it to never allow or to permit it if the Master requests it. We purposely did not allow for this option to be set on system startup as that could render the computer inoperable from the console.
• When the screen is blanked, a helpful and informative message will be displayed on the console that is not visible to the remote control user. The built-in message reads “An administrator is controlling this system remotely using PC-Duo Host”.
• The screen blanking technique employed is not effective on the “WinLogon” desktop, only the “Default” desktop (that represents the logged-in user’s desktop). The “WinLogon” desktop is used for the Ctrl+Alt+Del screen, for login prompts (including switch user), and before any user logs into the screen. Because we cannot blank the screen in these contexts, the Host will instead present a watermark-style message on the screen to alert the Remote Control user that although screen blanking is requested, the current screen is visible on the console. (The message displayed is “Screen Blanking has been requested but is not in effect on this screen”.)
• As a security measure, the PC-Duo Host locks the desktop if a remote control connection drops while Screen Blanking is in effect.
• Our input suppression cannot be block the console user from triggering the Ctrl+Alt+Del sequence. From a logged-in desktop, this brings the user to a system screen of choices Lock, Switch User, Sign Out, etc. However, all other mouse and keyboard input remains suppressed on all screens and circumstances, so a console user that hits Ctrl+Alt+Del cannot actually disrupt the remote control user beyond than that. The Master user is prioritized over the console user in this case and the only recourse for the console user would be to hit the power button on their machine.
• If the Master loses network connectivity to the Host, or drops unexpectedly in any way while screen blanking is in effect, the console user will remain blocked for up to 45 seconds while the network connection times out and then be put into the lock screen where they can then enter credentials to get back to their desktop.
