9.4.7 Connecting to a remote X server – xhost

xhost allows access based on hostnames. This is very insecure. The following will disable host checking and allow connections from anywhere if a TCP/IP socket connection is allowed (see Using X over TCP/IP, Section 9.4.6):

     $ xhost +

You can re-enable host checking with:

     $ xhost -

xhost does not distinguish between different users on the remote host. Also, hostnames (addresses actually) can be spoofed.

This method must be avoided even with more restrictive host criteria if you're on an untrusted network (for instance with dial-up PPP access to the Internet). See xhost(1x).