Introduction

Such complicated names for something quite simple (though very practical).

  • Exporting a display allows one user to transfer GUI applications to another user
  • Forwarding an X11 connection allows transferring GUI applications from one user to another

In short, you might think they’re the same thing! But not exactly.

Exporting the Display

Let’s say I’m connected as the user “deimos” and I launch a shell with the user “hostin”. I want to access the GUI of hostin. First, I authorize my deimos user to accept connections from any user:

  $ xhost +
access control disabled, clients can connect from any host

Now I want to know what my current display is:

  $ echo $DISPLAY
:0.0

Then I connect as hostin and export my display to deimos:

  $ su - hostin
$ export DISPLAY=:0.0

Now I just need to test with the hostin user:

  $ xclock

Ta-da! The clock appears in my deimos session even though it’s launched by hostin :-)

You can also do this with a remote machine by specifying the host (here are the lines to replace for the host deimos.fr):

  deimos: $ xhost + deimos.fr
hostin:$ export DISPLAY=deimos.fr:0.0

Forwarding X

We can forward our little X window through SSH. For this, on the SSH server (/etc/ssh/sshd_config):

  X11Forwarding yes

This line must be set to yes.

Then, for the client to receive the window, you must connect with the -X argument:

  $ ssh -X xxx@mycompany.com
$ xclock

Once again, ta-da! :-)

References

Create an X terminal

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Last updated 31 Aug 2008, 12:00 CEST. history