XHOST(1)            UNIX Programmer's Manual             XHOST(1)



NAME
     xhost - server access control program for X

SYNOPSIS
     xhost [[+-]name ...]

DESCRIPTION
     The xhost program is used to add and 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 which 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.

     Hostnames that are followed by two colons (::) are used in
     checking DECnet connections; all other hostnames are used
     for TCP/IP connections.

     User names contain an at-sign (@).  When Secure RPC is being
     used, the network independent netname (e.g.,
     "unix.uid@domainname") can be specified, or a local user can
     be specified with just the username and a trailing at-sign
     (e.g., "joe@").

OPTIONS
     Xhost accepts the following command line options described
     below.  For security, the options that effect access control
     may only be run from the "controlling host".  For worksta-
     tions, this is the same machine as the server.  For X termi-
     nals, it is the login host.

     [+]name The given name (the plus sign is optional) is added
             to the list allowed to connect to the X server.  The
             name can be a host name or a user name.

     -name   The given name is removed from the list of allowed
             to connect to the server.  The name can be a host
             name or a user name.  Existing connections are not
             broken, but new connection attempts will be denied.
             Note that the current machine is allowed to be
             removed; however, further connections (including
             attempts to add it back) will not be permitted.
             Resetting the server (thereby breaking all connec-
             tions) is the only way to allow local connections
             again.

     +       Access is granted to everyone, even if they aren't
             on the list (i.e., access control is turned off).




HP-UX 9.0 August 1992       Release 5                           1

XHOST(1)            UNIX Programmer's Manual             XHOST(1)



     -       Access is restricted to only those on the list
             (i.e., access control is turned on).

     nothing If no command line arguments are given, a message
             indicating whether or not access control is
             currently enabled is printed, followed by the list
             of those allowed to connect.  This is the only
             option that may be used from machines other than the
             controlling host.

DIAGNOSTICS
     For each name added to the access control list, a line of
     the form "name being added to access contro list" is
     printed.  For each name removed from the access control
     list, a line of the form "name being removed from access
     contro list" is printed.

FILES
     /etc/X*.hosts

SEE ALSO
     X(1), Xserver(1)

ENVIRONMENT
     DISPLAY to get the default host and display to use.

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

     This is not really a bug, but the X server stores network
     addresses, not host names.  If somehow you change a host's
     network address while the server is still running, xhost
     must be used to add the new address and/or remove the old
     address.

COPYRIGHT
     Copyright 1988, Massachusetts Institute of Technology.
     See X(1) for a full statement of rights and permissions.

AUTHORS
     Bob Scheifler, MIT Laboratory for Computer Science,
     Jim Gettys, MIT Project Athena (DEC).










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