Access to Unix Systems using X Windows
The methods you can use to login to CUS and Thor depend on what type of terminal you are using; specifically, whether you are running an X-server program such as eXceed, XWin etc. If you are not running an X-server, then you need a text-based login method as described in "Access to Unix systems from text terminals"If you are using an X server on your own machine, please see "X Server Configuration" and ensure that your system is configured correctly; many X servers are supplied with a configuration which is inherently insecure.
X Servers
On the PWF, eXceed is provided for logging onto CUS and Thor. See Leaflet M521: "An Introduction to Vista-eXceed - a DIY course".For personal Linux boxes, the simplest way to log on using XFree86 is to use X -query hostname on the command line, or to configure xdm to automatically start the X server.
Running X-clients on other machines
There are two things you need to do to display X-clients from other machines on one display.- Firstly, you must give the machine on which you wish to run the
X-client the 'key' to the X-server. That will allow the client to
prove that it has the authority to connect to the X-server.
Note that you should not use the xhost command to communicate this authority;
the xauth command should be used instead, as described below.
Copying the key across is done using xauth:
xauth extract - $DISPLAY | rsh otherhost.cam.ac.uk xauth merge -
- Secondly, you need to tell the X-client which X-server to display
on. This is done by setting DISPLAY on the remote machine. The
following are equivalent:
rsh otherhost.cam.ac.uk DISPLAY=$DISPLAY Mosaic xon otherhost.cam.ac.uk Mosaic
If you happen to be using a Linux machine, life is much easier: use the Computing Service's replacement for xon: xcmd. It contains both xauth and xon in one program, sets the DISPLAY correctly and gives better help when errors happen. See Access to Thor from Personal Linux Boxes or view the xcmd source.
xhost
It's worth putting in a section about xhost, to explain why it is such a bad thing.- xhost +hostname allows access to all users on that host, and
- xhost + (without a hostname) allows access to all users throughout the entire Internet.
Last updated by Peter Benie <pjb1008@cam.ac.uk>
unix-support@ucs.cam.ac.uk
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The title of this document is:
Access to the CUS and Thor using X Windows
URL:
http://www-uxsup.csx.cam.ac.uk/doc/remote_access/xwindows.html