How to Install Nagios 3.x on Centos 6.7 final release

What Is Nagios Core:-

Nagios Core is an Open Source system and network monitoring application. It watches hosts and services that you specify, alerting you when things go bad and when they get better.

System Requirments:-

1- Linux machine (In my case I am using Centos 6.7)
2- HTTPd, PHP with gd and CGI.

Nagios Installation:-

 Step 1- 

Add repository first to install Nagios

[root@odoo ~]# rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
Retrieving http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
warning: /var/tmp/rpm-tmp.2nIBRS: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing...                ########################################### [100%]
   1:epel-release           ########################################### [100%]
[root@odoo ~]#

[root@odoo ~]# rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
Retrieving http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
warning: /var/tmp/rpm-tmp.f5McIF: Header V4 DSA/SHA1 Signature, key ID 00f97f56: NOKEY
Preparing...                ########################################### [100%]
   1:remi-release           ########################################### [100%]

 Step 2- Complete installation & configuration part:

Run yum update

[root@odoo ~]# yum update

Install HTTPd server

[root@odoo ~]# yum install httpd

Install PHP

[root@odoo ~]# yum install php php-cli php-gh php-common

Install Nagios

[root@odoo ~]# yum install nagios nagios-plugins-all nagios-plugins-nrpe nrpe

Check Nagios version

[root@odoo ~]# nagios -v

Enable httpd and Nagios service to start auto during system boot or restart

[root@odoo ~]# chkconfig httpd on && chkconfig nagios on

Start httpd & Nagios service

[root@odoo ~]# service httpd start && service nagios start

Open Port 80 through iptables

[root@odoo ~]# vi /etc/sysconfig/iptables

Modify config file like below

# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

Save and exit from file & restart iptables service

[root@odoo ~]# service iptables restart

 Step 3- Setup Nagios login details

 Set Nagios user name and password

[root@odoo ~]# htpasswd -c /etc/nagios/passwd nagiosadmin
New password: *******
Re-type new password:  ******
Adding password for user nagiosadmin

 Step 4- Validate authentication & installation.

Check Nagios login using URL below

http://192.168.102.10/nagios/

After successful authentication, you will get the window like below.

!!!!!!!! Installation of Nagios completed successfully !!!!!!!!