How to install Nagios on CentOS 6+

INSTALLATION OF NAGIOS-CORE

1. # yum install gd gd-devel httpd php gcc glibc glibc-common

2. # mkdir /root/nagios

3.  # cd /root/nagios

4. # wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.4.4.tar.gz 
    # wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.16.tar.gz

5. tar xvzf nagios-3.4.4.tar.gz

6. # cd nagios

7. # ./configure

8. make all, make install, make install-init, make install-commandmode, make install-config, make install-webconf

9. # htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

10. # chkconfig nagios on
      # service nagios start

INSTALLATION OF NAGIOS PLUGIN

# cd ..
# tar xvzf nagios-plugins-1.4.15.tar.gz
# cd nagios-plugins-1.4.15
# ./configure
# make
# make install

# service httpd start
# chkconfig httpd on

Now Login your-ip/nagios, user: nagiosadmin password:your-password