Assignment 1 – Nagios_Nagios_Devops BC = 2330070508

Nagios Assignment - 1

To Be Performed:

1. Create a Nagios Master-Slave architecture and add 2 hosts

I used Ubuntu 22.04 and opened port 80.

EC2s used and Private IPs

nagios 10.0.1.146 my-linux-host1 10.0.1.164 my-linux-host2 10.0.1.228

^aa7b48

Installing Nagios Core From Source §

Documentation

#===== Ubuntu 20.x =====
#Prerequisites
#Perform these steps to install the pre-requisite packages.
sudo apt-get update -y
sudo apt-get install -y autoconf gcc libc6 make wget unzip apache2 php libapache2-mod-php7.4 libgd-dev
sudo apt-get install openssl libssl-dev -y
 
#Downloading the Source
cd /tmp
sudo wget -O nagioscore.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.14.tar.gz
tar xzf nagioscore.tar.gz
 
#Compile
cd /tmp/nagioscore-nagios-4.4.14/
sudo ./configure --with-httpd-conf=/etc/apache2/sites-enabled
sudo make all
 
#Create User And Group
#This creates the nagios user and group. The www-data user is also added to the nagios group.
sudo make install-groups-users
sudo usermod -a -G nagios www-data
 
#Install Binaries
#This step installs the binary files, CGIs, and HTML files.
sudo make install
 
#Install Service / Daemon
#This installs the service or daemon files and also configures them to start on boot.
sudo make install-daemoninit
 
#Install Command Mode
#This installs and configures the external command file.
sudo make install-commandmode
 
#Install Configuration Files
#This installs the *SAMPLE* configuration files. These are required as Nagios needs some configuration files to allow it to start.
sudo make install-config
 
 
#Install Apache Config Files
#This installs the Apache web server configuration files and configures Apache settings.
sudo make install-webconf
sudo a2enmod rewrite
sudo a2enmod cgi
 
#Configure Firewall
#You need to allow port 80 inbound traffic on the local firewall so you can reach the Nagios Core web interface.
sudo ufw allow Apache
sudo ufw reload
 
 
#Create nagiosadmin User Account
#You'll need to create an Apache user account to be able to log into Nagios.
#The following command will create a user account called nagiosadmin and you will be prompted to provide a password for the account.
sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
 
#Start Apache Web Server
#Need to restart it because it is already running.
sudo systemctl restart apache2.service
 
#Start Service / Daemon
#This command starts Nagios Core.
sudo systemctl start nagios.service

I verify that the Nagios server is up and running by accessing its GUI from the browser using the following URL: <Public IP>/nagios.
![[Pasted image 20231121194952.png|]] We login with the nagiosadmin we previously created

Since we haven’t installed Nagios Plugins yet, An error is displayed in the ‘Status Information’ of Hosts and Services.

Installing The Nagios Plugins §

Nagios Core needs plugins to operate properly. The following steps will walk you through installing Nagios Plugins 2.4.6.

Prerequisites §

Make sure that you have the following packages installed.

sudo apt-get install -y autoconf gcc libc6 libmcrypt-dev make libssl-dev wget bc gawk dc build-essential snmp libnet-snmp-perl gettext

Downloading The Source §

cd /tmp  
wget --no-check-certificate -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.4.6.tar.gz  
tar zxf nagios-plugins.tar.gz

Compile + Install §

cd /tmp/nagios-plugins-release-2.4.6/  
sudo ./tools/setup  
sudo ./configure  
sudo make  
sudo make install

Now the previous error disappears

Success

We are all set with the Nagios installation on Master

---

Adding 2 hosts §

To install prerequisites on Nagios agents, I chose to use pre-compiled packages instead of building from source. This approach is simpler and faster, as it involves installing packages directly from a package manager like apt-get, eliminating the need for manual source code compilation and installation.

sudo apt-get update
sudo apt-get install nagios-nrpe-server nagios-plugins
sudo nano /etc/nagios/nrpe.cfg
sudo /etc/init.d/nagios-nrpe-server restart

I edited the file /etc/nagios/nrpe.cfg to add the Nagios (master) private IP address.

Now, on the Nagios server, I need to configure it to interact with that client. To facilitate this, I will add a host file for each host. Consequently, I created host1.cfg and host2.cfg.”

vi /usr/local/nagios/etc/objects/host1.cfg

define host {
  use linux-server
  host_name my-linux-host1
  alias My Linux Host1
  address 10.0.1.164
}

vi /usr/local/nagios/etc/objects/host2.cfg

define host {
  use linux-server
  host_name my-linux-host2
  alias My Linux Host2
  address 10.0.1.228
}

Now, I will modify the main configuration file, nagios.cfg, to include the configuration files I just created, host1.cfg and host2.cfg.

sudo vi /usr/local/nagios/etc/nagios.cfg

I restart Nagios service

sudo systemctl restart nagios

In Nagios GUI I navigate to Current Status > Hosts and confirm newly added hosts

Success