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NOTE: CentOS Enterprise Linux 5 is built from the Red Hat Enterprise Linux source code. Other than logo and name changes CentOS Enterprise Linux 5 is compatible with the equivalent Red Hat version. This document applies equally to both Red Hat and CentOS Enterprise Linux 5.

21.3. Problems After Installation

21.3.1. Remote Graphical Desktops and XDMCP

If you have installed the X Window System and would like to log in to your Red Hat Enterprise Linux system using a graphical login manager, enable the X Display Manager Control Protocol (XDMCP). This protocol allows users to remotely log in to a desktop environment from any X Window System compatible client (such as a network-connected workstation or X terminal). To enable remote login using XDMCP, edit the following line in the /etc/X11/gdm/gdm-config file on the Red Hat Enterprise Linux system with a text editor such as vi or nano:



Edit the line to read Enable=true, save the file, and exit the text editor. Switch to runlevel 5 to start the X server:

/sbin/init 5

From the client machine, start remote X session using X. For example:

X :1 -query

The command connects to the remote X server via XDMCP (replace with the hostname of the remote X server) and displays the remote graphical login screen on display :1 of the client system (usually accessible by using the Ctrl-Alt-F8 key combination).

You may also access remote desktop sessions using a nested X server, which opens the remote desktop as a window in your current X session. Xnest allows users to open a remote desktop nested within their local X session. For example, run Xnest using the following command, replacing with the hostname of the remote X server:

Xnest :1 -query

21.3.2. Problems When You Try to Log In

If you did not create a user account in the Setup Agent, log in as root and use the password you assigned to root.

If you cannot remember your root password, boot your system as linux single.

Once you have booted into single user mode and have access to the # prompt, you must type passwd root, which allows you to enter a new password for root. At this point you can type shutdown -r now to reboot the system with the new root password.

If you cannot remember your user account password, you must become root. To become root, type su - and enter your root password when prompted. Then, type passwd <username>. This allows you to enter a new password for the specified user account.

If the graphical login screen does not appear, check your hardware for compatibility issues. The Hardware Compatibility List can be found at:

21.3.3. Your Printer Does Not Work

If you are not sure how to set up your printer or are having trouble getting it to work properly, try using the Printer Configuration Tool.

Type the system-config-printer command at a shell prompt to launch the Printer Configuration Tool. If you are not root, it prompts you for the root password to continue.

21.3.4. Apache-based httpd service/Sendmail Hangs During Startup

If you are having trouble with the Apache-based httpd service or Sendmail hanging at startup, make sure the following line is in the /etc/hosts file:  localhost.localdomain  localhost

  Published under the terms of the GNU General Public License Design by Interspire