1XHOST(1) General Commands Manual XHOST(1)
2
6 xhost - server access control program for X
7
9 xhost [[+-]name ...]
10
12 The xhost program is used to add and delete host names or user names to
13 the list allowed to make connections to the X server. In the case of
14 hosts, this provides a rudimentary form of privacy control and secu‐
15 rity. It is only sufficient for a workstation (single user) environ‐
16 ment, although it does limit the worst abuses. Environments which re‐
17 quire more sophisticated measures should implement the user-based mech‐
18 anism or use the hooks in the protocol for passing other authentication
19 data to the server.
20
22 Xhost accepts the following command line options described below. For
23 security, the options that affect access control may only be run from
24 the "controlling host". For workstations, this is the same machine as
25 the server. For X terminals, it is the login host.
26 -help Prints a usage message.
28 [+]name The given name (the plus sign is optional) is added to the list
30 allowed to connect to the X server. The name can be a host
31 name or a complete name (See NAMES for more details).
32 -name The given name is removed from the list of allowed to connect
34 to the server. The name can be a host name or a complete name
35 (See NAMES for more details). Existing connections are not
36 broken, but new connection attempts will be denied. Note that
37 the current machine is allowed to be removed; however, further
38 connections (including attempts to add it back) will not be
39 permitted. Resetting the server (thereby breaking all connec‐
40 tions) is the only way to allow local connections again.
41 + Access is granted to everyone, even if they aren't on the list
43 (i.e., access control is turned off).
44 - Access is restricted to only those on the list (i.e., access
46 control is turned on).
47 nothing If no command line arguments are given, a message indicating
49 whether or not access control is currently enabled is printed,
50 followed by the list of those allowed to connect. This is the
51 only option that may be used from machines other than the con‐
52 trolling host.
53
55 A complete name has the syntax ``family:name'' where the families are
56 as follows:
57 inet Internet host (IPv4)
59 inet6 Internet host (IPv6)
60 dnet DECnet host
61 nis Secure RPC network name
62 krb Kerberos V5 principal
63 local contains only one name, the empty string
64 si Server Interpreted
65 The family is case insensitive. The format of the name varies with the
67 family.
68 When Secure RPC is being used, the network independent netname (e.g.,
70 "nis:unix.uid@domainname") can be specified, or a local user can be
71 specified with just the username and a trailing at-sign (e.g.,
72 "nis:pat@").
73 For backward compatibility with pre-R6 xhost, names that contain an at-
75 sign (@) are assumed to be in the nis family. Otherwise they are as‐
76 sumed to be Internet addresses. If compiled to support IPv6, then all
77 IPv4 and IPv6 addresses returned by getaddrinfo(3) are added to the ac‐
78 cess list in the appropriate inet or inet6 family.
79 The local family specifies all the local connections at once. However,
81 the server interpreted address "si:localuser:username" can be used to
82 specify a single local user. (See the Xsecurity(7) manual page for more
83 details.)
84 Server interpreted addresses consist of a case-sensitive type tag and a
86 string representing a given value, separated by a colon. For example,
87 "si:hostname:almas" is a server interpreted address of type hostname,
88 with a value of almas. For more information on the available forms of
89 server interpreted addresses, see the Xsecurity(7) manual page.
90 The initial access control list for display number n may be set by the
92 file /etc/Xn.hosts, where n is the display number of the server. See
93 Xserver(1) for details.
94
96 For each name added to the access control list, a line of the form
97 "name being added to access control list" is printed. For each name
98 removed from the access control list, a line of the form "name being
99 removed from access control list" is printed.
100
102 X(7), Xsecurity(7), Xserver(1), xdm(1), xauth(1), getaddrinfo(3)
103
105 DISPLAY to get the default host and display to use.
106
108 You can't specify a display on the command line because -display is a
109 valid command line argument (indicating that you want to remove the ma‐
110 chine named ``display'' from the access list).
111 The X server stores network addresses, not host names, unless you use
113 the server-interpreted hostname type address. If somehow you change a
114 host's network address while the server is still running, and you are
115 using a network-address based form of authentication, xhost must be
116 used to add the new address and/or remove the old address.
117
119 Bob Scheifler, MIT Laboratory for Computer Science,
120 Jim Gettys, MIT Project Athena (DEC).
121X Version 11 xhost 1.0.9 XHOST(1)