Directory index forbidden by Options directive error for when displaying nagios

When you are unable to display the Nagios web after installation but encounter "Directory index forbidden by Options directive: .........." error. You need to set Apache to serve the file when the directory is requested.

To resolve the problem above. Go to

# vim /etc/httpd/conf/httpd.conf

Type the following into http.conf and restart apache and nagios

# service htpd restart
# service nagios restart