The shadowing feature is enabled by default when installing ThinLinc. You can disable this feature if required, using the following command.
# sudo tl-config /shadowing/shadowing_mode=reject
When the shadowing feature is disabled, all requests to shadow a user session is activly rejected. Details about this configuration parameter is described in /shadowing/shadowing_mode .
The above command should be run on all of the ThinLinc servers in your cluster.