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6. Common Configurations

6.1. Linux to Linux

6.1.2. X Terminal and Application Server

XDM runs on the application server:

  • Xserver: Contains no entries

  • Xaccess: Must permit the X terminal to connect

X terminal runs X using a direct query to the application server:

          /usr/X11R6/bin/X -query the.application.server
          

6.1.3. Group of Managed X Terminals

XDM runs on an application server:

  • Xserver: Lists each X terminal to be managed

  • Xaccess: Must permit each X terminal to connect

Each X terminal, just runs X, with suitable access control to permit XDM to connect to it.

          /usr/X11R6/bin/X -ac
        

6.2. Linux to Other Systems

It is possible to use a Linux X terminal to connect to another system running XDM. The same principles as above apply, but the specifics of configuring XDM (or its equivalent) will be specific to that system.

6.2.1. Linux and Solaris

You can run X on a Linux box, instructing it to query a Solaris machine as previously described:

          /usr/X11R6/bin/X -query the.solaris.server
         

Note that you may have to configure X on the Linux machine to use the font server from the Solaris box. Although my Linux box connected and logged in fine without doing this, the fonts used by CDE were not displayed correctly.

I have not got this to work yet, as I don't have a Solaris box that I have any control over - but I am told that a font entry in /etc/XF86config similar to the following should work - you may have to change the port number from 7200 to something else (7100 has been quoted at me before). Can anyone confirm that this works?

           FontPath "tcp/solaris.box:7200/all"
         

6.2.2. Linux and Windows

It is not possible to use X to remotely display Windows applications on a Windows box. It is possible to use X to display Windows versions of X applications on a Linux box, using a Windows X Server and Windows X applications (for example the XFree86 Win32 port - see Section 7)

It is possible to view Windows applications remotely on a Linux box using one of the following applications (which don't rely on X or XDM):

  • Windows Terminal Services (WTS). RDesktop is a Linux application that understands the 'RDP' protocol used by WTS. This enables Linux to act as a client to WTS (see Section 7).

  • Vitual Network Computing (VNC). This is an excellent platform independent remote desktop system that provides a bi-directional 'Windows or Linux' to 'Windows or Linux' networked desktop. It can be a bit slow, but works well (see Section 7).

    You can actually do quite strange things with VNC, such has having multiple machines connect and 'control' the desktop (and consequently 'fight' over control of the mouse :). It also doesn't maintain any state in the client, so you can leave your client, shutdown, bootup again, reconnect and carry on from where you left off. There is even a version of the viewer implemented as a Java applet, usable from any Java-enabled web browser.

6.3. Other Systems to Linux

If you have an X server for your system, it should be able to connect to a Linux XDM application server.

6.3.2. Windows and Linux

If you have an X server for windows that supports XDMCP queries, then it should be possible to configure it to query the Linux box. You should just run XDM on the Linux box as usual.

There are many commercial X Server implementations for Windows, and I will not list them all here. There is also a port of XFree86 to Windows, that makes use of the cygwin libraries (used to port many GNU/Linux tools to Windows - see Section 7). This works well.

The following batch file would start the cygwin XFree86 X server on Windows and connect to a Linux box (or any OS/machine running XDM), assuming a default installation of cygwin and XFree86 in c:\cygwin (save it as xdm.bat):

           @echo off
           if "%1"=="" goto noserver
           goto allok
           :noserver
           echo Usage: xdm servername
           goto end

           :allok
           set path=%PATH%;\cygwin\bin;\cygwin\usr\X11R6\bin
           c:
           chdir \cygwin\usr\X11R6\bin
           XWin -query %1

           :end