MirOS Manual: xhost(1)


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.

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.

     -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 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).

     -       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

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             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

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

     When Secure RPC is being used, the network independent net-
     name (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 com-
     piled 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.

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), 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 (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

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     address while the server is still running, 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).

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