Yes, NX does (normally) ask. However, to work from remote i have configured the NX-Server that it dont ask for permission. Because if it asks, and i sit remote, a cannot click on the button “ok” 😉
It would be very helpfull to have a list, e.g. in the NX-Database, where permitted users to connect can be stored. The idea is, in this case there are many system users (UsersX), which can connect to a machine (e.g. via active directory). However, there is only one “owner” of the machine (User1), which normally sits in front of the screen (session :0) and in this case he is the only one who should be able to connect via NX to that session. For that i need a kind of a white-list to allow only User1 to connect.