xhost
(1)
Name
xhost - server access control program for X
Synopsis
/usr/bin/xhost [[+-]name ...]
Description
User Commands XHOST(1)
NAME
xhost - server access control program for X
SYNOPSIS
/usr/bin/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 affect 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 complete name (See
NAMES for more details).
-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 complete name (See NAMES for more
details). Existing connections are not broken, but
new connection attempts will be denied. Note that
the current machine is allowed to be removed; how-
ever, 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 cur-
rently enabled is printed, followed by the list of
those allowed to connect. This is the only option
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User Commands XHOST(1)
that may be used from machines other than the con-
trolling 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 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.
The local family specifies all the local connections at
once. However, the server interpreted address
"si:localuser:username" can be used to specify a single
local user. (See the Xsecurity(5) manual page for more
details.)
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.
For more information on the available forms of server inter-
preted addresses, see the Xsecurity(5) manual page.
The initial access control list for display number n may be
set by the file /etc/Xn.hosts, where n is the display number
of the server. See Xserver(1) for details.
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
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User Commands XHOST(1)
control list" is printed.
SEE ALSO
X(5), Xsecurity(5), Xserver(1), xdm(1), xauth(1), netser-
vices(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,
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.
WARNINGS
Oracle Solaris is secure by default. See Xserver(1) which
details how to re-enable remote connections to the X server
as in previous releases.
AUTHORS
Bob Scheifler, MIT Laboratory for Computer Science,
Jim Gettys, MIT Project Athena (DEC).
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |x11/x11-server-utilities |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
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