xauth [ -f authfile ] [ -vqibn ] [ command arg ... ]
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 interactively, 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.
The following options may be used with xauth. They may be given individually (e.g., -q -i) or may combined (e.g., -qi).
The following commands may be used to manipulate authority files:
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 display, as usual. If untrusted is used, clients that connect using this authorization will be considered 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 this authorization will be valid. If the authorization 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 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.
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 different 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:
% 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 .
This xauth program uses the following environment variables:
X(7), Xsecurity(7), xhost(1), Xserver(1), xdm(1), startx(1), Xau(3).
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