Installation Nagios on EC2 Ami instance and monitor a generic host on Internet.

Installation

Install Nagios core package

sudo yum install nagios

Install plugins. Without the plugins you will not be able to monitor even localhost.

sudo yum install nagios nagios-plugins-all

Install SNMP

yum install net-snmp-utils net-snmp

Post installation configuration

Set up user name and password. A default username is nagiosadmin

sudo htpasswd -c -b  /etc/nagios/passwd nagiosadmin nagiospassword