Running OUI fails with Xlib: No protocol specified

Problem Description
Using VNC Viewer (a software which is used to show GUI in the unix server from any windows machine) whenever you run runInstaller as oracle database user it fails with below message.
$ ./runInstaller
Starting Oracle Universal Installer...

Checking installer requirements...

Checking operating system version: must be redhat-3, SuSE-9, redhat-4, UnitedLinux-1.0, asianux-1 or asianux-2
Passed


All installer requirements met.

Preparing to launch Oracle Universal Installer from /tmp/OraInstall2009-03-03_12-34-07AM. Please wait ...[oracle@localhost database]$ Xlib: connection to ":1.0" refused by server
Xlib: No protocol specified

Exception in thread "main" java.lang.InternalError: Can't connect to X11 window server using ':1.0' as the value of the DISPLAY variable.
at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
at sun.awt.X11GraphicsEnvironment.<clinit>(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(Unknown Source)
at java.awt.Window.init(Unknown Source)
at java.awt.Window.<init>(Unknown Source)
at java.awt.Frame.<init>(Unknown Source)
at oracle.ewt.popup.PopupFrame.<init>(Unknown Source)
at oracle.ewt.lwAWT.BufferedFrame.<init>(Unknown Source)
at oracle.sysman.oio.oioc.OiocOneClickInstaller.<init>(OiocOneClickInstaller.java:378)
at oracle.sysman.oio.oioc.OiocOneClickInstaller.main(OiocOneClickInstaller.java:2091)

Cause of the problem
The client users are not authorized to connect to the X Server.

This is by default settings that access control is enabled and client users will not be access the X server.

Solution of the Problem
In order to enable client users to access the X Server as a root user issue "xhost +".
[oracle@localhost database]$ su - root
Password:
[root@localhost ~]# xhost +
access control disabled, clients can connect from any host

Now as oracle user you will be able to run runInstaller successfully.
[root@localhost ~]# su - oracle
[oracle@localhost ~]$ ./runInstaller

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