So, you want to tunnel your xwindows session?  No problem.  The first step is to determine what type of machine you will be connecting from.  If it is a Windows machine, continue here.  If it is a Unix/Linux machine, head for the *nix section.

Tunneling from a Windows Machine

Program Requirements: 

  • PuTTY
  • Xming X Server

 If you don't have Xming, you can download it from Software Licensing (U of A Login Required).  You will be redirected to SourceForge, where you can download the Xming installer (the 'Download' link).  You will also need the  additional fonts, which are available under the 'Files' link.  Install both with the default settings.

 You'll also an SSH client; we recommend PuTTY, available here.

 Now that we have both of the necessary programs, the first thing you need to do is start up your Xwindows server (Xming or you own personal X Server).  NOTE: Xming doesn't bring up a window on your screen, just an entry in your system tray (across from the start menu).  Next, fire up PuTTY.  This will bring up a window just like figure A.

 Figure A 

First, in the box labeled 'Host Name', enter the name of the server you're trying to connect to.  For most College of Engineering services, this will be either (for basic services like checking e-mail or editing your website) or (for computationally-intensive programs).  Then, on the left side of the window, click the plus sign (+) next to 'SSH' to expand that section, and then select 'X11'.  Make sure that the option 'Enable X11 forwarding' is checked (Figure B).

 Figure B 

At this point, you are all set.  To start your SSH session, click "Open". If this is your first time connecting, you may receive a warning that the RSA key is not recognized.  This is normal, but only if it's your first time connecting.  Accept the warning, and enter your username and password when prompted.  When you receive a login prompt, you can test the X forwarding by entering the command "xclock".  If you see a window containing a clock pop up, you are now tunneling xwindows correctly!  Not showing up?  Open a support ticket with us at

Tunneling from another Unix/Linux Machine

On the client, simply type the command "ssh -X username@server".  The "-X" tells ssh to tunnel your X11 windows.  To test the connectivity, try the command "xclock".  If you see a clock appear, you are all set.