nagios configuration in Linux step by step

Question: how to configure Nagios in Linux?

Question : step by step nagios configuration in centos ?

Question: Linux monitoring tool

Nagios is an awesome Open Source monitoring tool, it provides you more comprehensive monitoring environment to always keep an eye on your all machines/networks whether you are in your data center or just your small labs.With Nagios, you can monitor your remote hosts and their services remotely in a single window. It shows warnings and indicates if something goes wrong on your servers which eventually helps us to detect some problems before they occur. It helps us to reduce downtime and business losses.

OS - CentOS 7 64 bit

IP  - 172.17.20.100

Hostname - nagiosserver.linuxtopic.com

Step 1:

## Install  Dependencies

    yum install -y httpd php gcc glibc glibc-common gd gd-devel make net-snmp

Step 2:

## Create Nagios user & group:

useradd nagios

groupadd nagiosgroup

## Add Nagios and apache user to the nagcmd group

usermod -G nagiosgroup nagios

usermod -G nagiosgroup apache

Step 3:

## Download Nagios 4.3 from Offical site "https://www.nagios.org/downloads/" and unpack any directory "or" Download sourceforge.net

mkdir /tmp/nagios

cd /tmp/nagios

wget https://excellmedia.dl.sourceforge.net/project/nagios/nagios-4.x/nagios-4.3.1/nagios-4.3.1.tar.gz

wget https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz

tar xvf nagios-4.3.1.tar.gz

tar xvf nagios-plugins-2.2.1.tar.gz

Step 4:

## Configure Nagios & Compile 

./configure --with-command-group=nagiosgroup

##  Compile and install all the binaries with make command and make install command

make all

make install

Step 5:

## Install the init scripts for Nagios:

   make install-init

## install command-mode.

   make install-commandmode

## Install sample nagios files

   make install-config

## Install & Configure Web Interface for Nagios

   make install-webconf

Step 6:

## --- Install Nagios Plugins

cd ..
cd nagios-plugins-*
./configure --with-nagios-user=nagios --with-nagios-group=nagiosgroup

   

make

make install

Step 7:

##------ Customize nagios configuration:

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

## Now find an uncomment this line by deleting the #:

   #cfg_dir=/usr/local/nagios/etc/servers

   cfg_dir=/usr/local/nagios/etc/servers

## Create Directory

mkdir /usr/local/nagios/etc/servers

chown nagios:nagios /usr/local/nagios/etc/servers

## Configure Nagios Contacts

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

   email                           nagios@linuxtopic.com        ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******

Step 8:

## Configure check_nrpe Command

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

## Add the following to the end of the file:

define command{

       command_name check_nrpe

       command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

}

Step 9:

## Verify nagios configuration file :

   /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Step 10:

   

## --- Configure Apache

    sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

   >Enter a password at the prompt & Remember it as you will need it to access the Nagios web interface.

## Note: Add user name in "/usr/local/nagios/etc/cgi.cfg" if your user not a nagiosadmin

Step 11:

## Restart Service

/etc/init.d/nagios restart

systemctl start nagios.service

systemctl restart httpd.service

Step 12:

Access Nagios on Web Browser

http://172.17.20.100/nagios

Dashboard Window

Hosts Window

Services Windows

Part 1: Nagios Core 4.X configuration in Linux

Part 2: Add Remote hosts and service in Nagios

Part 3: Monitor MySQL/MariaDB Using check_mysql Plugin

Part 4: Monitor Tomcat using check_tomcat Plugin