Nmap NSE 6.01: x11-access

Checks if you're allowed to connect to the X server. If the X server is listening on TCP port 6000+n (where n is the display number), it is possible to check if you're able to get connected to the remote display by sending a X11 initial connection request. In reply, the success byte (0x00 or 0x01) will determine if you are in the 'xhost +' list. In this case, script will display the message: 'X server access is granted'.