XHOST(1)                       X Version 11                        XHOST(1)
                                 Release 6.1



 NAME    [Toc]    [Back]
      xhost - server access control program for X

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

 DESCRIPTION    [Toc]    [Back]
      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 userbased
 mechanism or use the hooks in the protocol for passing other
      authentication data to the server.

 OPTIONS    [Toc]    [Back]
      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 workstations, this is the same machine as
      the server.  For X terminals, it is the login host.

      -help   Prints a usage message.

      [+]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 connections) 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).

      -       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.

 NAMES    [Toc]    [Back]
      A complete name has the syntax ``family:name'' where the families are



 Hewlett-Packard Company            - 1 -             HP-UX 11.23 March 2003






 XHOST(1)                       X Version 11                        XHOST(1)
                                 Release 6.1



      as follows:

      inet    Internet host (IPv4)
      inetv6  Internet host (IPv6)
      dnet    DECnet host
      nis     Secure RPC network name
      krb     Kerberos V5 principal
      local   contains only one name, the empty string

      The family is case insensitive.  The format of the name varies with
      the family.

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

      For backward compatibility with pre-R6 xhost, names that contain an
      at-sign (@) are assumed to be in the nis family.  Otherwise they are
      assumed to be Internet addresses. If compiled to support IPv6, then
      all IPv4 and IPv6 addresses returned by getaddrinfo(3) are added to
      the access list in the appropriate inet or inetv6 family.

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

 FILES    [Toc]    [Back]
      /etc/X*.hosts

 SEE ALSO    [Toc]    [Back]
      X(1), Xsecurity(1), Xserver(1), xdm(1), getaddrinfo(3)

 ENVIRONMENT    [Toc]    [Back]
      DISPLAY to get the default host and display to use.

 BUGS    [Toc]    [Back]
      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).

      The X server stores network addresses, not host names.  This is not
      really a bug.  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.

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


 Hewlett-Packard Company            - 2 -             HP-UX 11.23 March 2003