Working on a remote Linux machine like tara usually involves connecting
through SSH and entering commands into a terminal. Sometimes it's useful
to work with GUI-based applications on the remote machine as well. This
page will provide an overview for Linux and Windows users to accomplish
this. For the rest of this page, we'll refer to the machine at your desk
as the "local" machine, and the one you're SSHing to as the "remote" machine.
Imagine the following scenario. We're producing some
PDF graphics on tara, and we want
to view them (say with the acroread program) without having to transfer
them to our local computer first. Let's see how to do this through SSH.
You can download the sample PDF to your account on tara if you'd like to
Note that the examples on this page show our older cluster hpc as the remote
host, but the process is exactly the same for tara.
If your local computer is a Linux machine, it probably doesn't need additional
software. The screenshots below are from Ubuntu 9.04, but any Linux distribution
with OpenSSH should behave similarly. If you start a regular SSH session and then
try to run acroread, you'll probably get an error.
Let's start a new SSH session, by using the following command
Now if we run acroread, a new window will appear on our desktop.
Note that a "-X" may be used instead of "-Y" to make an X connection. There
are subtle differences between the two, where use of "-Y" implies a higher
level of trust in the remote machine, but may not always be available.
You may use both flags together to ensure an X connection is made.
There are other options as well such as different encryption
schemes, and adding compression. If you're interested, you might want to check
the OpenSSH website.
For Windows users, there are two basic programs you'll need: a terminal program
and an X-server. We illustrate Windows Vista here, but XP should work similarly.
You probably already have a terminal program to make basic SSH connections to
tara. But for this section, we'll show how to use:
freely available terminal client
Xming an X-server; public
domain version is freely available (get the one called "Xming", not "mesa" or "fonts",
if you just want to get started quickly).
Download and install both programs to your local machine. Once that's
done, we'll set up a PuTTY session and enable X11 forwarding.
Make sure to specify "localhost:0" as the X display location, as shown above.
If you leave it blank, your performance will suffer noticeably.
If we try to run acroread on our PDF file, we get an error. (And if you haven't
enabled X11 forwarding in the PuTTY session, you'll get a different error).
Now we need to run our X Windows server. Start Xming - you'll know that
it's running when a black "X" icon shows up in your task area.
Now let's try to launch acroread in the terminal once again. This time a
window should pop up with our plot. If your network connection to tara isn't
so great, your X11 window might be slow to update.
If the SSH connection is broken or the X-Server is stopped, any open remote
X11 windows will close. Also, you might have some trouble logging out of PuTTY
until you've closed your X windows.
To see the setup in complete detail, here's a video walkthrough posted by a
Youtube user (or follow this
Also see the
for Xming for many more possibilities.
We've seen how to run acroread remotely to view graphics on the server from a
local Windows or Linux machine. There are many other uses for X11 forwarding
such as: using a graphical text editor like gvim or xemacs, running Matlab
or similar tools in a graphical environment, or previewing a LaTeX paper after
making some edits.