Nagios

Nagios is an open-source software for the continuous monitoring of systems, networks and infrastructure. It runs plugins stored on a server that is connected with a host or another server on your network or the internet. In case of any failure, Nagios alerts about the issues so that the technical team can perform the recovery process immediately.

History of Nagios:

➢ In the year 1999, Ethan Galstad developed it as a part of netsaint distribution. ➢ 2002, Ethan renames the project to “Nagios” because of trademark issues with the name “netsaint”.

➢ 2009, Nagios releases its first commercial version, Nagios XI. ➢ In 2012, Nagios was again renamed Nagios Core.

➢ It uses port numbers 5666, 5667 and 5668 to monitor its client. Why Nagios? ➢ Detect all types of network or server issues.

➢ Helps to find the root cause of the problem which allows you to get the permanent solution to the problem.

➢ Reduce downtime.

➢ Active monitoring of the entire infrastructure.

➢ Allow you to monitor and troubleshoot server performance issues.

➢ Automatically fix problems.

Features of Nagios:

➢ Oldest and latest.

➢ Good log and database system.

➢ Informative and attractive web interface.

➢ Automatically send alerts if the condition changes.

➢ Helps you to detect network errors or server crashes.

➢ You can monitor the entire business process and IT infrastructure with a single pass.

➢ Monitor network services like http, smtp, snmp, ftp, ssh, pop, DNS, LDAP, IPMI etc.

Phases of Continuous Monitoring:

1. Define: develop a monitoring strategy

2. Establish: how frequently you are going to monitor it.

3. Implement

4. Analyze data and report finding

5. Respond

6. Review and update

   Nagios Architecture:

   Nagios is a client-server architecture. Usually on a network, a Nagios server is running on a host and plugins are running on all the remote hosts which should you monitor. How does Nagios work?

   ➢ Mention all details in configuration files.

   ➢ Daemon read those details of what data to be collected.

   ➢ Daemon uses NRPE plugins to collect data from nodes and store it in its database.

   ➢ Finally shows everything in the dashboard.

   Pre-requisites:

   • Httpd (browser)

   • Php (dashboard)

   • Gcc and gd (compiler)

   • Makefile (to build)

   • Perl (script)

   Main configuration file:

   /usr/local/Nagios/etc.Nagios.cfg All monitoring things called as service. For e.g: 5 servers – 4 checks each Then you have to monitor 5*4= 20 services

   Dashboard overview:

   In the dashboard, you can see Host: down, unreachable, up, recovery, none Service: warning, unknown, critical, recovery, pending Installation of Nagios on Linux: To start Nagios core installation, you must have your EC2 instance up and run and have already configured SSH access to the instance. Step-1: install pre-requisites software on your EC2 machine prior to Nagios installation like apache, php, gcc compiler and gd development libraries.

#sudo su

#yum install httpd php

#yum install gcc glibc glibc-common

#yum install gd gd-devel

Step-2: create account information you need to setup a Nagios user, run the following commands,

#adduser -m Nagios

#passwd Nagios

#Now it will ask to enter new password give ‘12345’ as password.

#groupadd Nagioscmd

#usermod -a -G Nagioscmd Nagios

#usermod -a -G Nagioscmd apache

Step-3:

download Nagios core and the plugins. Create a directory for storing the downloads.

#mkdir ~/downloads

#cd ~/downloads

Download the source code tarballs of both Nagios and the Nagios plugins.

#wget http://prdownloads.sourceforge.net/sourceforge/Nagios/Nagios-4.0.8.tar.gz

#wget http://Nagios-plugins.org/download/Nagios-plugins-2.0.3.tar.gz Step-4: complete and install Nagios extract the Nagios source code tarball

#tar zxvf Nagios-4.0.8.tar.gz

#cd Nagios-4.0.8

Run the configuration script with the name of the group which you have create in the above step.

#./configure –with-command-grouo=Nagioscmd

Compile the Nagios source code

#make all

Install binaries, init script, sample config files and set permissions on the external command directly.

#make install

#make install-init

#make install-config

#make install-commandmode

Setp-5:

configure the web interface

#make install-webconf

Step-6:

create a ‘Nagiosadmin’ account for login into Nagios web interface, set password as well.

#htpasswd -c /usr/local/Nagios/etc/htpasswd.users Nagiosadmin

Asking for a password, set a new pwd

#service httpd restart

Step-7:

compile and install the Nagios plugins. Extract the Nagios plugins source code tarball.

#cd ~/downloads tar zxvf Nagios-plugins-2.0.3.tar.gz

#cd Nagios-plugins-2.0.3

Compile and install the plugins

#../configure --with-Nagiosuser=Nagios --with-Nagios-group=Nagios

#make

#make install

Step-8:

start Nagios. Add Nagios to the list of system services and have it automatically start when the system boots.

#chkconfig --add Nagios

#chkconfig Nagios on

Verify the sample Nagios configuration files

#/usr/local/Nagios/bin/Nagios -v

#usr/local/Nagios/etc/Nagios.cfg

If there are no errors, start Nagios

#service Nagios start

#service httpd restart

Step-9:

copy public ip of EC2 instance and paste in google chrome, in given way

For e.g 20.1.1.1/Nagios/Nagios

Ask for username- Nagiosadmin

Password-