How to Install Nagios?

Nagios Installation

• In this series we will be installing nagios on ubuntu. The versions used in this series are
  • Nagios: 4.4.5
  • Nagios Plugin: 2.2.1
  • Ubuntu: 18.04
• The installation used in this series will be from the link over here
• The nagios recommends installing the core version by downloading, compling and installing the code
• Following are the steps which we will follow
• Update Ubuntu packages and ensure the following softwares are installed

sudo apt-get update
sudo apt-get install -y autoconf gcc libc6 make wget unzip apache2 php libapache2-mod-php7.2 libgd-dev

sudo apt-get install -y libmcrypt-dev libssl-dev bc gawk dc build-essential snmp libnet-snmp-perl gettext

• Download the source of nagios and untar

cd /tmp
wget -O nagioscore.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.5.tar.gz
tar xzf nagioscore.tar.gz

• Compile the code

cd /tmp/nagioscore-nagios-4.4.5/
sudo ./configure --with-httpd-conf=/etc/apache2/sites-enabled
sudo make all

• Create user and group

sudo make install-groups-users
sudo usermod -a -G nagios www-data

• Install Binaries

sudo make install

• Install Service / Daemon

sudo make install-daemoninit

• Install Command mode

sudo make install-commandmode

• Install Apache Configuration Files

sudo make install-webconf
sudo a2enmod rewrite
sudo a2enmod cgi

• Create nagiosadmin User Account

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin 
# Enter password on prompt

• Download the Nagios Plugin source code

cd /tmp
wget --no-check-certificate -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.2.1.tar.gz
tar zxf nagios-plugins.tar.gz

• Compile and Install

cd /tmp/nagios-plugins-release-2.2.1/
sudo ./tools/setup
sudo ./configure
sudo make
sudo make install

• Restart Nagios and apache

sudo systemctl start nagios.service
sudo systemctl stop nagios.service
sudo systemctl restart nagios.service
sudo systemctl status nagios.service

• Now navigate to http://<ipaddress>/nagios

Nagios Important Paths

Configuration Item	Path
Configuration Directory	/usr/local/nagios
Nagios Configuration File	/usr/local/nagios/nagios.cfg
Nagios local state directory	/usr/local/nagios/var/
Nagios current state file	usr/local/nagios/var/status.dat