The xhost program is used to add and to delete host names or user names to the list allowed to make connections to the X server. In the case of hosts, this provides a rudimentary form of privacy control and security. It is only sufficient for a workstation (single user) environment, although it does limit the worst abuses. Environments that require more sophisticated measures should implement the user-based mechanism or use the hooks in the protocol for passing other authentication data to the server.
The xhost(1) man page is available at http://www.uni-bayreuth.de/cgi-bin/manpages/xhost/1 or http://www.bsdi.com/bsdi-man?proto=1.1&apropos=0&msection=ALL&query=xhost.