1XHOST(1) General Commands Manual XHOST(1)
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6 xhost - server access control program for X
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9 xhost [[+-]name ...]
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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
17 require more sophisticated measures should implement the user-based
18 mechanism or use the hooks in the protocol for passing other authenti‐
19 cation 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 user name.
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 user name.
35 Existing connections are not broken, but new connection
36 attempts will be denied. Note that the current machine is
37 allowed to be removed; however, further connections (including
38 attempts to add it back) will not be permitted. Resetting the
39 server (thereby breaking all connections) is the only way to
40 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
76 assumed to be Internet addresses. If compiled to support IPv6, then all
77 IPv4 and IPv6 addresses returned by getaddrinfo(3) are added to the
78 access list in the appropriate inet or inet6 family.
79 Server interpreted addresses consist of a case-sensitive type tag and a
81 string representing a given value, separated by a colon. For example,
82 "si:hostname:almas" is a server interpreted address of type hostname,
83 with a value of almas. For more information on the available forms of
84 server interpreted addresses, see the Xsecurity(7) manual page.
85 The initial access control list for display number n may be set by the
87 file /etc/Xn.hosts, where n is the display number of the server. See
88 Xserver(1) for details.
89
91 For each name added to the access control list, a line of the form
92 "name being added to access control list" is printed. For each name
93 removed from the access control list, a line of the form "name being
94 removed from access control list" is printed.
95
97 X(7), Xsecurity(7), Xserver(1), xdm(1), xauth(1), getaddrinfo(3)
98
100 DISPLAY to get the default host and display to use.
101
103 You can't specify a display on the command line because -display is a
104 valid command line argument (indicating that you want to remove the
105 machine named ``display'' from the access list).
106 The X server stores network addresses, not host names, unless you use
108 the server-interpreted hostname type address. If somehow you change a
109 host's network address while the server is still running, and you are
110 using a network-address based form of authentication, xhost must be
111 used to add the new address and/or remove the old address.
112
114 Bob Scheifler, MIT Laboratory for Computer Science,
115 Jim Gettys, MIT Project Athena (DEC).
116X Version 11 xhost 1.0.4 XHOST(1)