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Searching in: Articles & FAQs
ID: AR07M00851
Applies to: NoMachine Server
Added on: 2015-07-06
Last update: 2019-06-11
How to enable the blanking of the remote physical screen when somebody is connected

This feature is available with NoMachine servers version 5 or later.

When the screen blanking is active, the local user will see a black screen on the physical monitor while somebody is connected from remote.

Operations made on the physical screen are not shown and the local user cannot interact with the desktop until the remote user logs-out.

See also:

How to blank the physical screen of the remote machine when somebody is logged in from remote

i) The screen blanking of the NoMachine (server) host can be activated from the User Interface in the 'Server preferences' Area.

To open the User Interface, click on the !M icon in the system tray to open the context menu and choose 'Show the service status' -> 'Security' panel.

Select the 'Lock the physical screen when somebody connects' option.

Note for server version 5 or 4:
the item in the !M context menu is 'Show the connection status' or 'Show the server status' if you are not using NoMachine free.


ii) You can reach 'Server preferences' also in this way: open the NoMachine User Interface from Programs menu or Application, click on 'Settings' and click on the 'Server preferences' link at the bottom of the panel.

iii) Administrators may also activate the screen blank feature by editing the server configuration file (server.cfg). Uncomment and set the following key:

EnableScreenLock 1

To disable the screen blanking, set EnableScreenLock 0.



- For multi-node environments
Enabling or disabling screen blanking has to be configured on each of the remote nodes by editing the corresponding server.cfg.

- For Linux hosts
On some Linux distributions, gamma adjustments applied to blank the screen do not affect the cursor which remains visible. The local user, however, cannot control it with the physical mouse.

- For Mac OS X 10.7/10.8/10.9/10.10/10.11 and macOS 10.12/10.13
Mouse will be locked, but keyboard lock is not available on Mac.
This limitation is no longer present on macOS 10.14 or later.

- For macOS 10.12.6
The screen cannot be blanked reliably only on this specific macOS version. Previous OS X versions and macOS 10.13 do not exhibit this behavior.

- For virtual hosts
Screen blanking is available for physical hosts, it is not supported on virtual machines since it has effect on the physical monitor.

- Monitor brightness is automatically adjusted
The physical display is obscured as expected, but screen flickers and flashes making the desktop content to be shown intermittently. See also: