xhost(X)                 X Version 11 (Release 4)                   xhost(X)



 Name

    xhost - server access control program for X

 Syntax

    xhost [[+-]hostname ...]

 Description

    xhost modifies the list of machines that are allowed to make connections
    to the X server.  This provides a rudimentary form of privacy control and
    security.  It is only sufficient for a workstation (single user) environ-
    ment, although it does limit the worst abuses. Environments that require
    more sophisticated measures should use the hooks in the protocol for
    passing authentication data to the server.

    The server initially allows network connections only from programs run-
    ning on the same machine or from machines listed in the file
    /etc/X*.hosts (where * is the display number of the server).  The xhost
    program is usually run either from a startup file or interactively to
    give access to other users.

 Options

    xhost accepts the command line options described below.  For security,
    the options that affect access control may only be run from the same ma-
    chine as the server.

    [+]hostname
            adds hostname (the plus sign is optional) to the list of machines
            that are allowed to connect to the X server

    -hostname
            removes hostname from the list of machines that are allowed to
            connect to the server.  Existing connections are not broken, but
            new connection attempts are denied.  Note that the current ma-
            chine is allowed to be removed; however, further connections
            (including attempts to add it back) will not be permitted.
            Resetting the server (thereby breaking all connections) is the
            only way to allow local connections again.

    +       grants access to everyone, even if they aren't on the list of
            allowed hosts (that is, access control is turned off)

    -       restricts access to only those machines on the list of allowed
            hosts (that is, access control is turned on)

    If no command line arguments are given, xhosts prints to standard output
    the list of hosts that are allowed to connect along with a message indi-
    cating whether or not access control is currently enabled. If the DISPLAY
    variable specifies a remote server, you can use this option to obtain a
    list of machines that are allowed to connect with the remote server.
    This is the only option that does not have to be executed from the ma-
    chine running the server.

 Files

    /etc/X*.hosts

 See also

    X(X), Xsco(X)

 Environment


    DISPLAY specifies the default host and display to use.

 Limitations

    You can't specify a display on the command line because ``-display'' is a
    valid command line argument that indicates that you want to remove the
    machine named ``display'' from the access list.

 Copyright

    Copyright 1988, Massachusetts Institute of Technology.
    See X(X) for a full statement of rights and permissions.