Technical Notes

XDMCP Connections to Red Hat Linux 6.2
Technical Note 1523
Last Reviewed 30-Jun-2005
Applies To
Reflection X 2008
Reflection X version 12.0 through 14.x
Red Hat Linux version 6.2
Summary

Red Hat Linux version 6.2 includes default security features that prevent Reflection X from establishing an XDMCP connection to the Red Hat linux host. This technical note details the steps required to configure Red Hat Linux 6.2 to allow Reflection X XDMCP connections.

Note: For information about configuring Red Hat Linux 7.0 - 9.0 for remote XDMCP, see Technical Note 1680.

About the X Display Manager

The X Display Manager provides a graphical replacement for the host's command line login prompt when users connect over the X Display Manager Protocol (XDMCP). Red Hat provides support for the Gnome Display Manager (gdm), the KDE Display Manager (kdm), and the X Display Manager (xdm). Each of these display managers can be configured to automatically start the GNOME or KDE X Windows System graphical desktop environment.

Modifying Red Hat Linux 6.2 for XDMCP Connections

The following sections provide steps for configuring Red Hat Linux 6.2 for XDMCP connections using gdm, kdm, or xdm:

• Using GNOME's GDM X Display Manager
• Using KDE's KDM X Display Manager
• Using the Xdm X Display Manager

Note: You must be logged into your Red Hat Linux host as root to make these edits.

You can log on at either the host console or from your PC using the linux template (for Reflection version 10.x and earlier use the linux.rxc template) provided with Reflection X. (Most linux hosts do not allow you to log on as root remotely, therefore, if you use the linux or linux.rxc template, first log on using a normal user account, and then use the su command at the xterm command prompt to log in as root.)

Note: GNOME and KDE must be installed on your system prior to following these configuration steps. Red Hat 6.2 comes with GNOME 1.0.55 and KDE 1.1.2.

Using GNOME's GDM X Display Manager

To configure Red Hat Linux 6.2 to use gdm, follow the steps below.

1. Edit the /etc/sysconfig/desktop file to define which X desktop environment loads on connection.
   1. Open the /etc/sysconfig/desktop file.
   2. Add the following new line. Note: This entry is case sensitive.

3. Save the file.
2. Edit the /etc/X11/gdm/gdm.conf file.
   1. Open the /etc/X11/gdm/gdm.conf file.
   2. Under the "[xdmcp]" heading, change the default entry of Enable=0 to Enable=1.
   3. Save the file.

You should now be able to establish an XDMCP connection using Reflection X.

Using KDE's KDM X Display Manager

To configure Red Hat Linux 6.2 to use kdm, follow the steps below.

1. Edit the /etc/sysconfig/desktop file to define which X desktop environment loads on connection.
   1. Open the /etc/sysconfig/desktop file.
   2. Add the following new line. Note: This entry is case sensitive.

3. Save the file.
2. Edit the /etc/X11/xdm/Xaccess file.
   1. Open the /etc/X11/xdm/Xaccess file.
   2. Verify that the following lines appear as shown below.

3. Save the file.
3. Edit the /etc/X11/xdm/xdm-config file.
   1. Open the /etc/X11/xdm/xdm-config file.
   2. Comment out the requestPort command by inserting an exclamation point (!) in front of the command line, as shown below:

3. Save the file.

You should now be able to establish an XDMCP connection using Reflection X.

Using the XDM X Display Manager

To configure Red Hat Linux 6.2 to use xdm, follow the steps below.

1. Edit the /etc/sysconfig/desktop file to define which X desktop environment loads on connection.
   1. Open the /etc/sysconfig/desktop file.
   2. Add a new line for the X desktop you wish to use. Note: This entry is case sensitive.

3. Save the file.
2. Edit the /etc/inittab file.
   1. In the editor of your choice, open the /etc/inittab file.
   2. Under the heading "# Default runlevel", change the default to:

3. Under the heading "# Run xdm in runlevel", insert a pound (#) at the beginning of the entry to comment out the current command. For example, the edit line should appear as follows

4. Under the heading "#Run xdm in runlevel", add the following command line:

5. Save the file.
3. Initialize the /inittab changes.

4. Edit the /etc/X11/xdm/Xaccess file.
   1. Open the /etc/X11/xdm/Xaccess file.
   2. Under the heading "# Default runlevel", verify that the following lines appear as shown below.

3. Save the file.
5. Edit the /etc/X11/xdm/xdm-config file.
   1. Open the /etc/X11/xdm/xdm-config text file.
   2. Comment out the requestPort command by inserting an exclamation point (!) in front of the command line, as shown below:

3. Save the file.

You should now be able to establish an XDMCP connection using Reflection X.

Related Technical Notes

1229	Troubleshooting XDMCP Connections to UNIX and Linux Hosts
1680	XDMCP Connections to Red Hat Linux 7.0 or Higher
9992	Reflection X Technical Notes