What is Nagios? Nagios Configure & Install Tutorial Guide for Beginner

Introduction

As you browse sites for Nagios, there are only a few websites that have given information on this wonderful monitoring tool. So, I believe that this blog post for “Nagios Tutorial” would be a clear idea of what Nagios is, its configuration, installation, and continuous monitoring with Nagios. The Nagios Monitoring tool keeps a close eye on your entire IT infrastructure, services, business processes, and the servers, etc.

Let us give a quick start to this blog “Nagios Core Tutorial” by discussing the continuous monitoring concept and why we need it. Then we will discuss what is Nagios, Nagios installation & configuration tutorial guide for beginners.

Nagios Monitoring Tool Tutorial: What is Continuous Monitoring?

Once the application is deployed to the server, the role of continuous monitoring comes into existence. The process is all about taking care of Company infrastructure and responding immediately as soon as some error occurs. The concept is not new but it is around for a long time.

The technique you must have heard about is the static analysis that is responsible to detect, respond or report the logs but the analysis is not so much accurate as expected by the organizations. With continuous monitoring, you can perform and respond to each of the activities in the best possible way.

When we discuss continuous monitoring, it is necessary that all pieces of information should be connected well like database, warehouse, security tools, security management system, AI (Artificial Intelligence), security intelligence, data analytics, etc. Connecting different pieces together in a well-organized manner is the crux of the process that makes continuous monitoring a more successful and useful requirement by the organizations.

Further, the process is performed on a continuous (on-going) basis that reports immediately about the risks that can be faced by the Company for its poor infrastructure. You can also check the behavior of networks and data analytics reports when required. According to a saying, if you cannot ‘measure’ risks how will you ‘manage’ them and continuous monitoring is the solution that works best here.

Nagios Monitoring Tool Tutorial: Why do we need Continuous Monitoring?

Continuous Monitoring has the capability to detect system errors before they could have negative impacts on your business productivity. Here, is a quick list of features that explain to you why continuous monitoring is useful –

• The process helps in detecting network errors or server crashes.
• With CM, you can detect or report any type of infrastructure issues quickly.
• It also helps in maintaining security issues and service availability.
• You can troubleshoot or monitor the performance issues of the server.
• The process gives you a perfect idea of infrastructure upgrades, how can you make it even better that suits Company needs.
• The process has the capability of reporting issues at first glance only.
• The issues can be fixed automatically as soon as they are identified during the monitoring process.
• On successful completion of continuous monitoring, it makes sure that it does not have any negative impact on your Company infrastructure and business operations.
• The entire business process and IT infrastructure can be monitored in a single pass only.

What is Nagios?

Nagios is useful for continuous monitoring of applications, servers, or business processes, etc. inside a DevOps culture. It gives information to the technical staff about any performance issues or drawbacks in the system. When you use Nagios, you don’t have to give much explanation of how an unseen defect in the infrastructure can affect your organizational health badly.

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Consider the diagram given above to get a clear idea of Nagios working – Nagios is running on a server where plug-ins are installed and running automatically. They further contact the hosts/servers on your network and give you the status message in two different forms – one is Web Interface and the other is SMS or Email. Further, Nagios Server as shown in the diagram earlier works as a scheduler and runs selected scripts after a repeated time interval. As soon as the requirement changes, the previous scripts will be stored and new scripts will run based on needs. In brief, the working of Nagios is based on Plug-ins that give the confirm status of server, application, or infrastructure issues.

Nagios Monitoring Tutorial: Why do we Need Nagios?

  Here are some best reasons why you need Nagios DevOps Tool for your organization.

• It can identify all possible networks and server problems.
• It can identify the root cause of the server problem.
• It can actively monitor the entire infrastructure and business processes as needed.
• It can troubleshoot tough server issues.
• It helps in infrastructure updates before it results in system failures.
• It maintains the security issues and the availability of the service.
• It can automate the problem fixes as needed.

Nagios Monitoring Tutorial: History of Nagios DevOps tool

  The foundation of the tool was kept in 1996 that can run under Linux OS.

• In 1999, a separate Nagios Plugin project was started by the team.
• It was named Ethan earlier and renamed to Nagios DevOps tool in 2002.
• In 2005, it became the project of SourceForge.net during the month of June.
• In 2009, Nagios Enterprises released its first commercial version with the name Nagios XI
•  In 2012, Nagios name was changes to Nagios Core
• In 2016, The usage of the tool was on the top and it was able to cross more than 7,500,000 downloads directly from SourceForge.net.

Nagios Tutorial for Beginners: Features of Nagios

  Here are some considerable benefits of the tool, you should consider before start using it.

• It is highly scalable, secure, and manageable.
• It can store the data well with an excellent log management system.
• The tool has amazing web interfaces.
• It can send alerts automatically as soon as some changes are noticed.
• When services are going well, you don’t have to check the status of the host again and again.
•  It can identify network errors and server issues quickly.
• It can monitor the entire Infrastructure and business process in a single pass.

It can define or manage event handlers for resolving problems proactively.

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Nagios Tutorial for Beginners: Infrastructure

The Nagios platform is based on server-agent architecture. Take an example where Nagios is usually running over a host and plugins are designed to interact with the local network that should be monitored. Further, plug-ins send useful information to the scheduler that will be displayed over GUI.  

You also need to understand the working of NRPE – Nagios Remote plug-in Executor. With the NRPE, the plug-ins are executed over local servers or Linux machines. The objective of NRPE is to closely monitor the local resources over a remote resource.

As per the rule, these resources should not be exposed to the external machines. This is the reason why NRPE is needed along with other important components. You can better understand the working of NRPE by looking at the diagram below –

• Check_NRPE is a plugin that is available on the local monitoring machine.
• The NRPE daemon runs over the remote machine or Linux server and further monitors the resources and services for local and other hosts.
• As you can see, there is one secure SSL connection between the monitoring host and the remote/Linux host that is shown by the yellow arrow in the diagram.
• Let us have some hands-on practice by this quick tutorial i.e. Nagios Installation and Configuration.

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Let us have some hands-on practice by this quick tutorial i.e. Nagios Installation and Configuration.

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Nagios Installation and Configuration Tutorial Guide

Step 1 – Pre-requisites

Visit the URL - http://dl.fedoraproject.org/pub/epel/6/. As you soon, you browse the link, the following web page will display in front of you. Here, you can have to click on i386 and you will be redirected to the following page. Here you can see the link “epel-release-6-8.noarch.rpm”, now open the terminal and copy the location of the link over the terminal. This is the way you can download the repository on your system. So, you are done with the first step that was pre-requisites. Let us move to the second step now.

Step 2 – Installing Nagios, Nagios Plugins, and NRPE

Execute the following command on the terminal to install, Nagios plug-ins and NRPE (Nagios Resource Plug-in Executor), Apache and PHP. Apache is needed to monitor the recent web server status and PHP is required to process the dynamic content on your website. In the next step, you should enable the Apache server with the ‘chkconfig’ command as shown below in the screenshot. And once it is enabled start the Nagios and the Apache server with the ‘service’ command given below. Now create the swap file and avail minimum 1 GB space with the ‘dd’ command as given below – With the swap file, you can free up the necessary space and shift it somewhere else to the hard drive. You can use the “mkwsap” command to create the swap partitions and prepare the remote host for a swap area. The final command should be written like this as shown below – With the above command, only a temporary swap file is created. You can make the swap area permanent by adding it to the fstab file. With this command, we are done with the second step. Now let us move to the third step i.e. how to configure Nagios to access the Web interface.

Step 3 – Configure Nagios to access the Web Interface

At this step, you need to first set the password for the web interface by typing the following command over the terminal. Retype the password to confirm it. Now open the web browser and type the local hostname in the address bar.  Here, you need to enter the username and the password that is just given by you. By default, the username is Nagios admin. You can change the username in the advanced settings option. The password would be the same that we set earlier. In the end, press OK. It will show the Nagios dashboard in front of you as shown below. With these steps, you can monitor the localhost only. If you are interested in monitoring the remote host then you need to install the NRPE.

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Final Words:

With this Nagios Tutorial, we got a basic understanding of what is Nagios, about continuous monitoring, Nagios architecture, Nagios setup, installation, and its configuration. I am sure you must have enjoyed reading this blog and got something really new that was needed by you.

To know more about Nagios monitoring tool, you should join the DevOps certification program at JanBask Training and prepare yourself for a better future and wider job opportunities across the global marketplace.

Read: Best 37 DevOps Tools To Learn And Master In 2024: Docker, Git & More

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