Infrastructure Monitoring Using Nagios

Sourabh Deshmukh | Oct 26, 2020 min read


What is Nagios?

Nagios is a Monitoring tool used for IT Infrastructure Monitoring to maintain zero downtime for your Applications, Services, Systems, Databases and Business Processes etc. Nagios helps to detect failures and can be configured to alert technical staff so that the failures gets detected early and remediation process can be carried out before it affects entire Infrastructure or Customers.

Nagios Products

Nagios has four product according to your needs.

  • Nagios XI
  • Nagios Fusion
  • Nagios Core
  • Nagios Network Analyzer
  • Nagios Log Server

You can find Demo of all this tools provides by official Nagios Website.

You can get Download this tools from here.

Nagios Core


Nagios core is free whereas other products of Nagios are paid tools. Nagios Core comes with less features compared with paid version of Nagios XI.


The benefits you get from using Nagios Core are

  • Monitoring
  • Alerting
  • Reporting
  • Maintenace
  • Planning


  • Visibility
  • Reporting
  • Proactive Planning
  • Awareness
  • Problem Remediation
  • Comprehensive Monitoring
  • Multi-Tenant Capabilities
  • Extendable Architecture

If you want to know more visit Benefits and Features of Nagios Core.

Nagios Core Installation on Centos

I will be using Centos 8 minimal image for demonstration. For other distributions or OS refer to the following documetation.


Disable SELinux as we dont need it for demonstration. You can configure it according to your needs.

sed -i 's/SELINUX=.*/SELINUX=disabled/g' /etc/selinux/config
setenforce 0

Check the current status of your SELinux mode using following command.


The following dependencies are required for building and running nagios on you system.

dnf install -y gcc glibc glibc-common perl httpd php wget gd gd-devel

Instalation from Source -

Here I am using latest release version Nagios 4.4.6.

tar -zxvf nagios-4.4.6.tar.gz

Now we have the source code on system lets compile it.

./configure && make all

We have now compiled the source code. Lets add the users to manage config files required for Nagios. The following make file creates nagios user and adds apache user in nagios group.

make install -groups-users
usermod -a -G nagios apache

Now, lets install HTML, CGI snf binary files and install Daemon or service.

make install
$ make install-daemoninit

We are ready with our service. You can enable service using

systemctl enable httpd.service

Lets install command mode and configuration files.

make install-commandmode
make install-config
make install-webconf

Now we need to update our firewall rules to access nagios dashboard on browser.

firewall-cmd --zone=public --add-port=80/tcp
firewall-cmd --zone=public --add-port=80/tcp --permanent

This will add rules to firewall config. make sure to use a correct port while configuring firewall. It’s time add authentication for accessing nagios dashboard in browser. I will be using Simple HTTP authentication here. Our nagios authentication will be stored in htpasswd.users file in encrypted format. The followed word nagiosadmin is our username for accessing dashboaed.

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

This will prompt you for entering your password. Enter you password. It will again prompt you for confirmation of password just enter again the same password. We will now add httpd config file. You can get sample httpd file from sample-config folder inside extracted tar file. Copy that config file into httpd configuration.

cp sample-config/httpd.conf /etc/httpd/conf.d/

Now we will start both the services.

systemctl start nagios && systemctl start httpd

Open your browser and try to access nagios dashboard by http:///nagios My system assigned IP is so In my case I will access using when I access it in browser the browser will ask for username and password. Just enter the same username and password we created above.

nagios auth

After entering credentials press enter and you will be presented with following Nagios Dashboard.

nagios dashboard

We have configured nagios successfully. In next posts I will demonstrate about installation of plugins and configuration of nagios for monitoring.

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