XAUTH(1) UNIX Programmer's Manual XAUTH(1)
xauth - X authority file utility
xauth [ -f authfile ] [ -vqibn ] [ command arg ... ]
The xauth program is used to edit and display the authoriza-
tion information used in connecting to the X server. This
program is usually used to extract authorization records
from one machine and merge them in on another (as is the
case when using remote logins or granting access to other
users). Commands (described below) may be entered interac-
tively, on the xauth command line, or in scripts. Note that
this program does not contact the X server except when the
generate command is used. Normally xauth is not used to
create the authority file entry in the first place; xdm does
that.
The following options may be used with xauth. They may be
given individually (e.g., -q -i) or may combined (e.g.,
-qi).
-f authfile
This option specifies the name of the authority file
to use. By default, xauth will use the file speci-
fied by the XAUTHORITY environment variable or .Xau-
thority in the user's home directory.
-q This option indicates that xauth should operate
quietly and not print unsolicited status messages.
This is the default if an xauth command is given on
the command line or if the standard output is not
directed to a terminal.
-v This option indicates that xauth should operate ver-
bosely and print status messages indicating the
results of various operations (e.g., how many
records have been read in or written out). This is
the default if xauth is reading commands from its
standard input and its standard output is directed
to a terminal.
-i This option indicates that xauth should ignore any
authority file locks. Normally, xauth will refuse
to read or edit any authority files that have been
locked by other programs (usually xdm or another
xauth).
-b This option indicates that xauth should attempt to
break any authority file locks before proceeding.
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Use this option only to clean up stale locks.
-n This option indicates that xauth should not attempt
to resolve any hostnames, but should simply always
print the host address as stored in the authority
file.
The following commands may be used to manipulate authority
files:
add displayname protocolname hexkey
An authorization entry for the indicated display
using the given protocol and key data is added to
the authorization file. The data is specified as an
even-lengthed string of hexadecimal digits, each
pair representing one octet. The first digit of
each pair gives the most significant 4 bits of the
octet, and the second digit of the pair gives the
least significant 4 bits. For example, a 32 charac-
ter hexkey would represent a 128-bit value. A proto-
col name consisting of just a single period is
treated as an abbreviation for MIT-MAGIC-COOKIE-1.
generate displayname protocolname [trusted|untrusted]
[timeout seconds] [group group-id] [data hexdata]
This command is similar to add. The main difference
is that instead of requiring the user to supply the
key data, it connects to the server specified in
displayname and uses the SECURITY extension in order
to get the key data to store in the authorization
file. If the server cannot be contacted or if it
does not support the SECURITY extension, the command
fails. Otherwise, an authorization entry for the
indicated display using the given protocol is added
to the authorization file. A protocol name consist-
ing of just a single period is treated as an abbre-
viation for MIT-MAGIC-COOKIE-1.
If the trusted option is used, clients that connect
using this authorization will have full run of the
display, as usual. If untrusted is used, clients
that connect using this authorization will be con-
sidered untrusted and prevented from stealing or
tampering with data belonging to trusted clients.
See the SECURITY extension specification for full
details on the restrictions imposed on untrusted
clients. The default is untrusted.
The timeout option specifies how long in seconds
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this authorization will be valid. If the authoriza-
tion remains unused (no clients are connected with
it) for longer than this time period, the server
purges the authorization, and future attempts to
connect using it will fail. Note that the purging
done by the server does not delete the authorization
entry from the authorization file. The default
timeout is 60 seconds.
The group option specifies the application group
that clients connecting with this authorization
should belong to. See the application group exten-
sion specification for more details. The default is
to not belong to an application group.
The data option specifies data that the server
should use to generate the authorization. Note that
this is not the same data that gets written to the
authorization file. The interpretation of this data
depends on the authorization protocol. The hexdata
is in the same format as the hexkey described in the
add command. The default is to send no data.
[n]extract filename displayname...
Authorization entries for each of the specified
displays are written to the indicated file. If the
nextract command is used, the entries are written in
a numeric format suitable for non-binary transmis-
sion (such as secure electronic mail). The
extracted entries can be read back in using the
merge and nmerge commands. If the filename consists
of just a single dash, the entries will be written
to the standard output.
[n]list [displayname...]
Authorization entries for each of the specified
displays (or all if no displays are named) are
printed on the standard output. If the nlist com-
mand is used, entries will be shown in the numeric
format used by the nextract command; otherwise, they
are shown in a textual format. Key data is always
displayed in the hexadecimal format given in the
description of the add command.
[n]merge [filename...]
Authorization entries are read from the specified
files and are merged into the authorization data-
base, superceding any matching existing entries. If
the nmerge command is used, the numeric format given
in the description of the extract command is used.
If a filename consists of just a single dash, the
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standard input will be read if it hasn't been read
before.
remove displayname...
Authorization entries matching the specified
displays are removed from the authority file.
source filename
The specified file is treated as a script containing
xauth commands to execute. Blank lines and lines
beginning with a sharp sign (#) are ignored. A sin-
gle dash may be used to indicate the standard input,
if it hasn't already been read.
info Information describing the authorization file,
whether or not any changes have been made, and from
where xauth commands are being read is printed on
the standard output.
exit If any modifications have been made, the authority
file is written out (if allowed), and the program
exits. An end of file is treated as an implicit
exit command.
quit The program exits, ignoring any modifications. This
may also be accomplished by pressing the interrupt
character.
help [string]
A description of all commands that begin with the
given string (or all commands if no string is given)
is printed on the standard output.
? A short list of the valid commands is printed on the
standard output.
Display names for the add, [n]extract, [n]list, [n]merge,
and remove commands use the same format as the DISPLAY
environment variable and the common -display command line
argument. Display-specific information (such as the screen
number) is unnecessary and will be ignored. Same-machine
connections (such as local-host sockets, shared memory, and
the Internet Protocol hostname localhost) are referred to as
hostname/unix:displaynumber so that local entries for dif-
ferent machines may be stored in one authority file.
The most common use for xauth is to extract the entry for
the current display, copy it to another machine, and merge
it into the user's authority file on the remote machine:
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% xauth extract - $DISPLAY | rsh otherhost xauth merge -
The following command contacts the server :0 to create an
authorization using the MIT-MAGIC-COOKIE-1 protocol.
Clients that connect with this authorization will be
untrusted.
% xauth generate :0 .
This xauth program uses the following environment variables:
XAUTHORITY
to get the name of the authority file to use if the
-f option isn't used.
HOME to get the user's home directory if XAUTHORITY isn't
defined.
$HOME/.Xauthority
default authority file if XAUTHORITY isn't defined.
Users that have unsecure networks should take care to use
encrypted file transfer mechanisms to copy authorization
entries between machines. Similarly, the MIT-MAGIC-COOKIE-1
protocol is not very useful in unsecure environments. Sites
that are interested in additional security may need to use
encrypted authorization mechanisms such as Kerberos.
Spaces are currently not allowed in the protocol name.
Quoting could be added for the truly perverse.
Jim Fulton, MIT X Consortium
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