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/gdm/custom.conf file on the Red Hat Enterprise Linux system with a text editor such as vi or nano:

Add the line 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 
s390vm.example.com

The command connects to the remote X server via XDMCP (replace s390vm.example.com 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 s390vm.example.com with the hostname of the remote X server:

Xnest :1 -query 
s390vm.example.com