To have reached this question, you should need a software for remote monitoring of electrical or non-electrical quantities, networks, services, etc.
According to Wikipedia – “Nagios, now known as Nagios Core, is a free and open source computer software application that monitors systems, networks, and infrastructure. Nagios offers to monitor and alerting services for servers, switches, applications, and services. It alerts users when things go wrong and alert them a second time when the problem has been resolved.”
In this article will be described how to install Nagios local server – step by step. In the document, the following packages are used – Nagios 4.2.1, Nagios Plugins2.1.2, and Ubuntu 16.04.
It is assumed, that the user is familiar with Linux and already has a workstation with Ubuntu 16.04.
You can continue reading this article or just switch to the updated one “How to install Nagios 4.3.4 local server on Ubuntu 18.04“
1. How to install Nagios local server – initial settings
1.1. Run terminal as root to install Nagios local server necessary packages
Installation and configuration of the required packages require administrator rights, so before downloading and installing the following packages put the following command in the console:
You will be asked for a password, then the console goes into the root mode.
1.2. Packages installation
The following packages should be installed:
sudo apt-get install apache2
sudo apt-get install php7.0-gd
sudo apt-get install libapache2-mod-php7.0
sudo apt-get install build-essential
sudo apt-get install libgd2-xpm-dev
1.3. Creating a new user
It is necessary to create a new user and group to which it belongs. Use the following commands:
usermod -G nagcmd nagios
usermod -a -G nagcmd www-data
1.4. Creating a directory for downloading Nagios packages
2. Compiling and installing Nagios
tar zxvf nagios-4.2.1.tar.gz
./configure –with-nagios-group=nagios –with-command-group=nagcmd
Depending on system configuration, it is possible to be displayed following error:
This error is caused by Nagios process. It tries to create a configuration file in the directory /etc/httpd.conf/.
But in Ubuntu, this configuration file should be placed in the directory /etc/apache2/sites-enabled/.
The following command should be used:
sudo /usr/bin/install -c -m 644 sample-config/httpd.conf /etc/apache2/sites-enabled/nagios.conf
sudo ls -l /etc/apache2/sites-enabled/
The result will be as follows:
3. Changing the e-mail address
The address nagios@localhost should be replaced with the desired email address. To save changes, use a keyboard shortcut Ctrl+X. After this choose Y and press Enter. The document remains with the same my name.
4. Configuring the Web interface, creating a user
After the execution of the following commands, a password for user nagiosadmin will be required.
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
sudo service apache2 restart
5. Compiling and installing of Nagios plugins
tar zxvf nagios-plugins-2.1.2.tar.gz
./configure –with-nagios-user=nagios –with-nagios-group=nagios
6. Start Nagios
ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Depending on the configuration of the system, it is possible Nagios process, not to start. In this case, perform the following steps in the terminal:
6.1. nagios.service file creation
sudo nano nagios.service
In this file, following rows should be inserted:
To save changes, use a keyboard shortcut Ctrl+X. After this choose Y and press Enter.
6.2. Copy the following configuration file
cp /etc/init.d/skeleton /etc/init.d/nagios
6.3. Edit the configuration file
sudo nano /etc/init.d/nagios
In the end of the file, following rows should be inserted:
6.4. Saving the file, changing the conditions of access to it
sudo chmod +x /etc/init.d/nagios
6.5. Edit apache2 configuration file
sudo nano /etc/apache2/sites-enabled/nagios.conf
Delete the # character from the row “Allow from 127.0.0.1”. This will allow Nagios process to be accessed at 127.0.0.1/nagios or localhost/nagios.
6.6. Start Nagios service
sudo service nagios start
7. Login into the Nagios via a WEB browser
The user interface is available at:
The username: nagiosadmin
The password: as set in step 4
8. Adding host to Nagios
To be added a host to the system, several configuration files should be changed. Changes are made through an editor in the console. It is recommended to stop Nagios during the changes:
sudo service nagios stop
It is recommended after any change in a file of the system to verify configuration using the following command:
– /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
So if there is a configuration error, only the last changed file should be checked.
8.1. Change of the main configuration file
The base installation of the system allows monitoring only of the local host (computer). It is necessary to allow to Nagios process access to other hosts – switches, routers or other servers.
sudo nano /usr/local/nagios/etc/nagios.cfg
After this command, an editor will be open.
From the last line #cfg_file=/usr/local/nagios/etc/objects/switch.cfg the character # should be removed.
This will allow Nagios process to access configuration file, where the host data are written.
8.2. Adding an information for the new host in the following configuration file
sudo nano /usr/local/nagios/etc/objects/switch.cfg
In the end of the file, details of the new host (TCW220) should be added
alias Teracom Ethernet Controller TCW220
After saving changes in the configuration file, you need to restart Nagios process.
sudo service nagios restart
The new host is now available through a WEB interface.
The basic installation of Nagios includes service for monitoring the host only. To add additional services should be available a plugin, which performs the service and posts the results in the user interface.
We hope that this article was helpful enough to learn how to install Nagios local server and use it with different hosts.