Secure Tunneling

Cygwin also lets you set up a remote desktop session through a secure SSH tunnel. First type X & at the Cygwin console to open a local X server. (The & sends the service into the background and ensures that you can continue using the console.) This command calls the X binary directly. The X server starts in a large window, with no terminal for setting up an SSH session. This approach helps you avoid closing the wrong window in the desktop environment and thus terminating all open applications. After opening the X window, go back to the Cygwin window and run the following command to launch a KDE desktop environment remotely:

DISPLAY=:0.0; ssh -Y -f \
  <IP-of-Linux-PC>; startkde

After setting DISPLAY, you need to run an SSH call that again releases the console after executing a command on the remote host (-f option). The -Y parameter initiates X forwarding in trusted mode, so the window manager can use the X instance remotely.

For Xfce, replace startkde with startxfce4; and for LXDE, use startlxde. Gnome 3 proved problematic in our lab with the gnome-session startup command: The desktop environment failed because of the lack of 3D support. A general method to enforce fallback mode over the network does not seem to exist.

Native Everything

Another option is to install a ported desktop environment (or at least a window manager) locally in the Cygwin environment. The desktop offers the look and feel of Linux – for remote applications, but also for locally installed ports. The standard Cygwin repository lets you install Windowmaker and the FWM and Twm window managers. Gnome, KDE, LXDE, Mate, ROX, Xfce, and the Sugar desktop environment are all available as Cygwin ports [5].

I tried to install KDE, and the libqt4 dependency turned up missing. Although libqt4 is available in the normal repositories, it is not provided in the Cygwin Ports version. To resolve the problem, I needed to restart the installer and integrate the appropriate package. After this step, I managed to launch a KDE desktop in the Cygwin environment (Figure 5), but only after a relatively long startup time.

Figure 5: Ported, not remotely executed: a full KDE desktop running in the Cygwin environment.

The Gnome shell was not available on the server, so I was unable to launch the Gnome desktop. The spartan Windowmaker environment (Figure 6) worked out of the box, however. The download volume is fairly small, and Windowmaker is included in the standard Cygwin repository.

Figure 6: The still experimental -mwextwm parameter lets you launch a transparent local Windowmaker environment.

The startx startup script is also used in the Cygwin environment to launch X plus a display manager. The following command opens a KDE session:

$ startx /usr/bin/startkde -- \
  -nodecoration

The start scripts for the other desktop environments are the same as for the remote calls. Before you launch any other programs, you need to set DISPLAY manually. The "Starting the Cygwin X Server" box gives more details. The Cygwin Installer also offers a graphical user interface named XLaunch, which removes the need for users to enter the command lines described in the box to users (Figure 7).

ssh -X <IP-of-Linux-PC>

Figure 7: The XLaunch program lets you launch without starting the Cygwin X server at the command line.

XWin.exe or X

A call to X only starts the X server; you launch programs that access the server at the Cygwin console after setting the DISPLAY=:0.0 shell variable. The Cygwin X server parameters differ in part from those of the Linux version and are described in the man page [9].