Manual: xauth
XAUTH(1) General Commands Manual XAUTH(1)
NAME
xauth - X authority file utility
SYNOPSIS
xauth [ -f authfile ] [ -vqibn ] [ command arg ... ]
DESCRIPTION
The xauth program is used to edit and display the authorization 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; the
program that starts the X server (often xdm or startx) does that.
OPTIONS
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 specified
by the XAUTHORITY environment variable or .Xauthority 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 verbosely 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. 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.
-V This option shows the version number of the xauth executable.
COMMANDS
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 autho‐
rization file. The data is specified as an even-lengthed string of hexadecimal digits, each pair represent‐
ing 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 character hexkey would represent a
128-bit value. A protocol 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 consisting of just a single period is
treated as an abbreviation for MIT-MAGIC-COOKIE-1.
If the trusted option is used, clients that connect using this authorization will have full run of the dis‐
play, as usual. If untrusted is used, clients that connect using this authorization will be considered un‐
trusted 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 this authorization will be valid. If the authorization re‐
mains unused (no clients are connected with it) for longer than this time period, the server purges the au‐
thorization, 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 be‐
long to. See the application group extension 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 transmission (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 command is used, entries will be shown in the numeric format used by the nex‐
tract command; otherwise, they are shown in a textual format. Key data is always displayed in the hexadeci‐
mal 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 database, su‐
perseding any matching existing entries. If the nmerge command is used, the numeric format given in the de‐
scription of the extract command is used. If a filename consists of just a single dash, the 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 begin‐
ning with a sharp sign (#) are ignored. A single 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 char‐
acter.
version This command shows the version number of the xauth executable.
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
Display names for the add, [n]extract, [n]list, [n]merge, and remove commands use the same format as the DISPLAY en‐
vironment 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
different machines may be stored in one authority file.
EXAMPLE
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:
% xauth extract - $DISPLAY | ssh 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 .
ENVIRONMENT
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.
FILES
$HOME/.Xauthority
default authority file if XAUTHORITY isn't defined.
SEE ALSO
X(7), Xsecurity(7), xhost(1), Xserver(1), xdm(1), startx(1), Xau(3).
BUGS
Users that have insecure 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 insecure 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.
AUTHOR
Jim Fulton, MIT X Consortium
X Version 11 xauth 1.1.2 XAUTH(1)