NAGIOS

Nagios is one of the well-knows tools for monitoring servers and services in a network. It works on a client-server structure that means there is a server regularly connects to Nagios clients and obtain the latest state of the servers and services.

In Nagios we define hosts, and services and we can group them together for ease of management.

A Host is an actual machine. e.g. a physical server or a work station.

We define a host as below:

define host {

        use                     generic-host

        host_name               ns1.ksa.com

        alias                   NameServer

        address                 10.10.0.4

        }

A service is an actual UDP, TCP, or ICMP that does specific job such as HTTP service. We define a service as below:

define service {     

        use                     generic-service

        host_name             ns1.ksa.com

        service_description   PING

        check_command               check_ping!100.0,20%!500.0,60%

        }

Nagios comes with a bunch of plugins and each of which does a specific job. As shown above, a PING service was defined to regularly check the state of the target (a Nagios client).

On each client a nagios-nrpe-server should be installed. This component allows the Nagios server to send the service/server health-check commands to the clients. It is installed with the following command.

sudo apt-get –y install nagios-nrpe-server

It should be configured that to which server the Nagios client should listen to.

allowed_hosts=10.10.0.5     //IP address of the nagios server

So far, we have deployed a Nagios Server on a raspberry pi and a Nagios client on the KSA’s main server. We have configured the Nagios to check the following services:

·            Number of running processes

·            * Disk usage

·           * Number of logged in users

·           *HTTP service monitoring

·         *  And MySql service monitoring

One of the functionalities of the Nagios is to notify network administrators when incidents happen. For example a server goes down or a service stops working. We will configure the Nagios to send us email when a service/server fails using our email server.