University Observatory Munich

Faculty of Physics at the Ludwig-Maximilians-University

Using the Cygwin X server and ssh

When working on a remote machine through ssh it may sometimes be useful to display a remotely generated plot on your local machine. This is possible when you have a local X server running, and your ssh connection can forward graphics display commands from the remote machine to your local machine. The easiest way to achieve this on Windows is by using the Cygwin tools.

To set this up, first download the Cygwin installer from https://www.cygwin.com/. Run the installer to set up the base system. This will add the Cygwin terminal to your start menu. Make sure you can start this and run simple commands such as ls in the terminal.

Then, run the installer again and select packages openssh, xorg-server, and (for testing) xeyes (select Full in the drop-down list at the top left, enter search terms in the Search field, and for each package you want to install choose the version number from the associated drop-down list instead of Skip).

To start the X server, open a Cygwin terminal and type

X -multiwindow

You can minimize the terminal window but don’t close it, otherwise the X server will terminate.

To verify that the X server is running correctly, open a second Cygwin terminal and type

export DISPLAY=:0
xeyes

This should open a follow-the-mouse demo in a separate window. If this works, you can terminate xeyes again (either by closing its window or by pressing Control-C in the terminal window). Now you can connect to a remote machine from the second terminal, using ssh with the -Y option (X11 forwarding), for example

ssh -4 -Y user@ltsp05.usm.uni-muenchen.de

Once you have authenticated with the correct password you can check that the graphics forwarding works, by entering xeyes at the remote prompt. This should open the follow-the-mouse demo on your screen just like it did for your locally installed version.