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 connec-
       tions 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.

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 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 break-
               ing 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
       A complete name has the syntax ''family:name'' where the families are as follows:

       inet      Internet host (IPv4)
       inet6     Internet host (IPv6)
       dnet      DECnet host
       nis       Secure RPC network name
       krb       Kerberos V5 principal
       local     contains only one name, the empty string
       si        Server Interpreted

       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 inet6 family.

       Server interpreted addresses consist of a case-sensitive type tag and  a  string  representing  a  given
       value,  separated  by a colon.  For example, "si:hostname:almas" is a server interpreted address of type
       hostname, with a value of almas.


DIAGNOSTICS
       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
       /etc/X*.hosts

SEE ALSO
       X(7), Xsecurity(7), Xserver(1), xdm(1), xauth(1), getaddrinfo(3)

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 (indi-
       cating that you want to remove the machine named ''display'' from the access list).

       The  X  server  stores network addresses, not host names, unless you use the server-interpreted hostname
       type address.  If somehow you change a host's network address while the server is still running, and you
       are  using  a  network-address  based  form of authentication, xhost must be used to add the new address
       and/or remove the old address.

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

X Version 11                      xhost 1.0.1                         XHOST(1)

http://bashconsole.org/man.1x.xhost