Nagios on Ubuntu
A comprehensive step-by-step guide to installing and configuring Nagios Core from source on Ubuntu, including dependency setup and web interface configuration.
Nagios is a powerful monitoring system that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes. In this post, I will walk through the basic steps to get Nagios up and running on an Ubuntu system.
Prerequisites
Before starting, ensure your package database is up to date:
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sudo apt-get update
Install Required Packages You will need to install several dependencies, including Apache, PHP, and build libraries:
sudo apt-get install build-essential apache2 php5-gd wget libgd2-xpm libgd2-xpm-dev libapache2-mod-php5 libssl-dev
Create User and Group Create a nagios user and a group for allowing external commands to be passed through the web interface:
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sudo useradd -m -s /bin/bash nagios
sudo passwd nagios
sudo groupadd nagcmd
sudo usermod -a -G nagcmd nagios
sudo usermod -a -G nagcmd www-data
Download and Extract Nagios Download the Nagios Core and Plugins source code (adjust version numbers as necessary):
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mkdir ~/downloads
cd ~/downloads
wget [http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.3.1.tar.gz](http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.3.1.tar.gz)
wget [http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz](http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz)
tar xzf nagios-3.3.1.tar.gz
cd nagios
Compile and Install Run the configuration script and compile the binaries:
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./configure --with-command-group=nagcmd
make all
sudo make install
sudo make install-init
sudo make install-config
sudo make install-commandmode
Configure the Web Interface Install the Nagios web config file in the Apache conf.d directory:
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sudo make install-webconf
Create a nagiosadmin account for logging into the Nagios web interface:
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sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Restart Apache to make the new settings take effect:
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sudo /etc/init.d/apache2 reload
Install Nagios Plugins Now, compile and install the plugins:
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cd ~/downloads
tar xzf nagios-plugins-1.4.15.tar.gz
cd nagios-plugins-1.4.15
./configure --with-nagios-user=nagios --with-nagios-group=nagios
make
sudo make install
Start Nagios
Verify the configuration and start the service:
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sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
sudo service nagios start
You can now access the Nagios web interface by navigating to http://localhost/nagios/ and logging in with the nagiosadmin credentials you created earlier.