Install epel repo if doesn’t already exist

Install nagios, nagios plugins and nrpe client on server

yum -y install nagios nagios-plugins-all nrpe

create “nagiosadmin” user and set a password for it

htpasswd -c /etc/nagios/passwd nagiosadmin

make nrpe start at boot and start nrpe service

/sbin/chkconfig nrpe on
/etc/init.d/nrpe start

Create a simple index.html so webserver responds and is up

echo "hello world" >> /var/www/html/index.html

Set nagios for boot and start nagios

/sbin/chkconfig nagios on
/etc/init.d/nagios start

# browse to server /nagios in my case http://puppet/nagios and login with nagiosadmin and the password you set above.

That will bring you to a page that looks like this…

Nagios Interface Screenshot