Monitoring Nagios
Team: Sheela Raj, Ilja Shustov
Group : Cyber Security Engineering (C21)
Page Created: 10 November 2016
Last modified:
Introduction
In this article, we will cover the installation of Nagios, a very popular open source monitoring system, on Ubuntu. We will cover some basic configuration, so you will be able to monitor host resources via the web interface. We will also utilize the Nagios Remote Plugin Executor (NRPE), that will be installed as an agent on remote hosts, to monitor their local resources.
Monitoring
Before You Begin
Check your current Ubuntu version & Upgrade
You can check your current ubuntu version by the following command:
lsb_release -a
If your machine is already running Ubuntu 16.04.1 LTS or higher than that, There is no need for you to upgrade the OS.
Otherwise you need to upgrade the OS by the following command:
sudo apt-get update && sudo apt-get upgrade
Note:
This article is written for a non-root user. Commands that require elevated privileges are prefixed with sudo. If you’re not familiar with the sudo command, you can check the Users and Groups guide.
Install the required package
As a prerequisite, Nagios requires the gcc compiler and build-essentials for the compilation, LAMP (Apache, PHP, MySQL) for the Nagios web interface and Sendmail to send alerts from the server.
To install all those packages, run the following command (it's just 1 line):
sudo apt-get install wget build-essential apache2 php apache2-mod-php7.0 php-gd libgd-dev sendmail unzip
Create Users and Groups
Create a user nagios, and a distinct group nagcmd.
Add nagios and the Apache user www-data, to the nagcmd group in order to run external commands on Nagios through the web interface
Use the following command to create:
To create user:
sudo useradd nagios
To create group:
sudo groupadd nagcmd
To add user to the group:
sudo usermod -a -G nagcmd nagios && sudo usermod -a -G nagcmd www-data
Installing Nagios
Download and extract Nagios
In your web browser, go to the Nagios Core DIY download page.It will ask you to register, If you prefer not to register for updates, click Skip to download.
Under Nagios Core, find the release that says Latest stable release under Notes, then copy the download link to your clipboard.
Now using wget and tar, download the Nagios and extract it.
To download, paste the copied link after wget:
wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.2.0.tar.gz
Command to extract:
tar -xzf nagios*.tar.gz
Now move to the newly created directory, by using the following command:
cd nagios-4.2.0
Compile Nagios
Before you build Nagios, you will have to configure it with the user and the group you have created earlier.
command to configure:
./configure --with-nagios-group=nagios --with-command-group=nagcmd
For more information please use: ./configure --help
Now compile Nagios with this command:
make all
To install Nagios
Now we can run these make commands to install Nagios, init scripts, and sample configuration files:
sudo make install
sudo make install-commandmode
sudo make install-init
sudo make install-config
/usr/bin/install -c -m 644 sample-config/httpd.conf /etc/apache2/sites-available/nagios.conf
And copy evenhandler directory to the nagios directory:
cp -R contrib/eventhandlers/ /usr/local/nagios/libexec/
chown -R nagios:nagios /usr/local/nagios/libexec/eventhandlers
Nagios Plugins
Nagios Plugins allow you to monitor services like DHCP, FTP, HTTP and NTP.
Download and extract the Nagios plugins
To use Nagios Plugins, go to Nagios Plugins downloads page and copy the download link for the current stable release.
Now using wget and tar, download and extract Nagios plugin.
Use the following command to move back into user's home directory:
cd ~
To download, paste the copied link after wget:
wget https://nagios-plugins.org/download/nagios-plugins-2.1.2.tar.gz
Command to extract:
tar -xzf nagios-plugins*.tar.gz
Now Change to the newly created directory by the following command:
cd nagios-plugins-2.1.2/
Install Nagios plugins
Install the Nagios plugin's with the following commands:
./configure --with-nagios-user=nagios --with-nagios-group=nagios --with-openssl
make
make install
