By default, users connecting to a host where a NoMachine Terminal Server for Linux product has been installed can share their NoMachine virtual desktop with other users.

To connect to another user's desktop and 'shadow' the virtual desktop:

1) Log-in to the NoMachine server.

2) Be sure to have the 'All desktops' view mode selected, so that you will be able to see also other users' sessions.

3) Select the virtual desktop where you want to connect and right mouse click on its icon.

4) It will open a menu with the 'Connect to session' item.

5) Click on 'Connect to session': the owner of this session will need to authorize your connection.

He/she will be prompted with a dialog showing your request to connect and the possibility to Deny your request, Accept it or Accept it in view mode only.

- For administrators -

a) To disable connections to virtual desktops set in the server configuration file: VirtualDesktopSharing 0. This setting also disables the listing of other users' virtual sessions in the client UI.

b) To forbid users to interact with the desktop once connected set in the server configuration: VirtualDesktopMode 0

c) To allow users connecting to the virtual desktop without explicit permissions, set: VirtualDesktopAuthorization 0

d) To define a pool user who can connect without explicit permissions, keep the authorization request on (VirtualDesktopAuthorization 1) and give to the user 'trusted' permissions: /etc/NX/nxserver --useradd USERNAME --trusted virtual

e) When the system account is the same, NoMachine assumes by default that the connecting user is also the same and performs the automatic migration of the session from one device to the other.  E.g. user A runs a virtual desktop. User B logs in from a different device but with the same usename and credentials of user A: session closes on the device of user A and it's re-opened on the device of user B.

To disable automigration, set in the server configuration in the ConnectPolicy key: automigrate=0 for example

ConnectPolicy autocreate=0,autoconnect=0,automigrate=0,desktop=0,dialog=0

For more detailed instructions, please refer to the Installation and configuration guide of your NoMachine server product, available in the Installation section at: https://www.nomachine.com/all-documents

b) and c) can be set also via the Server preferences interface:

- click on the !M icon in the system tray to open it, choose 'Show main window' and access the Settings -> Server  -> Security panel:

They correspond to the 'Require permission to let remote users connect' and 'Require permission to let the remote user interact with the desktop' options respectively.

More about the server interface is available in the Guide to the NoMachine Server UI in the Configuration section here: https://www.nomachine.com/all-documents