Beginner’s guide to Installing & Configuring NAGIOS server

Hello Linux-fanatics, in this tutorial we will learn to install and configure Nagios Monitoring tool.

Nagios server (AKA nagios core) is a very useful, open-source monitoring tool. With the help of Nagios server, we can monitor stats like ram usage, cpu usage, hdd usage along with other parameters of a number of machines/servers on single screen. If something goes wrong , its sends us warning by using sound or sending a mailto configured users or we can even configure Nagios to send a sms to a phone number.


Before we can install Nagios , we need some packages like httpd, php, gcc, glibc, glibc-comman & GD on our system.

To install all these packages, run following

$ yum install –y httpd php gcc glibc glibc-comman gd gd-devel make net-snmp

After all the packages are installed, we will now download the Nagios & its plugins source file. As of writing of this tutorial, Nagios 4.2.4  & Plugins 2.1.4 are the latest. You can directly download the files using link below or you can use wget also to get these files

$ wget

$ wget

Now we will start with installation of Nagios….


Step 1 – Create  a user & group for Nagios

We will add a user nagios & a group nagcmd

$ useradd nagios
$ passwd nagios             (enter a password)
$ groupadd nagcmd

Now, we will add nagios & apache to nagcmd group

$ usermod –G nagcmd nagios
$ usermod –G nagcmd apache

Step2- Extracting Nagios files

We will now extract the nagios & plugins files on our system

$ tar -xvf nagios-4.2.4.tar.gz
$ tar -xvf nagios-plugins-2.1.4.tar.gz

Step 3- Configuring Nagios-core

Now that we have extracted the Nagios file, we will now go to the extracted folder & compile those files to install Nagios server

$ cd nagios-4.2.4
$ ./configure – -with-command-group=nagcmd

after it’s completed, we will now run make & make install to complete our installation

$ make
$ make install

once these steps are done, we need to install init –scripts, commandmode & also need to install some sample  Nagios files

$ make install-init
$ make install-comandmode
$ make install-config

Step4 – Configuring Web-Interface

Once all the above installations are complete, we can now configure web-interface where we will do all the monitoring. To install web-interface, run the following command

$ make install-webconf

Our web-interface is now installed and a default user “nagiosadmin” has been created. We will now assign password to user “nagiosadmin

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

Step 5- Setting an email for sending alerts

To set an email to receive alerts , open

$ vi /usr/local/nagios/etc/objects/contacts.cfg

and enter an email address.

Step6- Installing the Nagios Plugins

Now, it’s time to install Nagios plugins

$ cd nagios-plugins-2.1.4/
$ ./configure – -with-nagios-user=nagios –with-nagios-group=nagios
$ make
$ make install

Step 7 – Verify Nagios files

In the last step of Nagios server installation, we will verify Nagios configuration file against a sample configuration file to make sure all the settings are Okay

$ /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

If all the settings made are correct you should not receive any error.

Now restart nagios server & httpd server

$ service nagios restart
$ chkconfig nagios on
$service httpd restart
$ chkconfig httpd on

Step 8- Logging into Web-interface

Open your browser & enter http://localhost/Nagios or http://IP-address/Nagios  in your address bar & you will be asked to enter the username & password. Upon entering the credentials, you can now see your Nagios Web-interface.

nagios server

nagios server

When you see service overview page, we can only see services of our localhost . That is because we have not added other host services on Nagios. In our next tutorial, we will discuss how can we add Windows & Linux hosts to Nagios server. Please share your queries/comments down below in the comment box.


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