Nagios Version : Nagios Core 4.0.8
OS Version : Red Hat Enterprise Linux Server release 6.2 (Santiago)
Installation document referred from following link :
http://www.tecmint.com/install-nagios-in-linux/
[root@server1 ~]# service httpd status
httpd (pid 13020) is running...
[root@server1 ~]# sestatus
SELinux status: disabled
[root@server1 ~]# netstat -an|grep 80
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:28002 0.0.0.0:* LISTEN
udp 0 0 0.0.0.0:52780 0.0.0.0:*
udp 0 0 127.0.0.1:58081 0.0.0.0:*
unix 2 [ ACC ] STREAM LISTENING 25180 /var/tmp/.oracle/sEXTPROC1529
unix 3 [ ] STREAM CONNECTED 41957880 /usr/local/nagios/var/rw/nagios.qh
[root@server1 ~]# tail -f /var/log/httpd/error_log
[Tue May 31 10:15:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:20:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:25:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:30:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:35:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:40:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:45:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:50:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/
[Tue May 31 10:55:31 2016] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/