Monitoring the Linux Server Using Nagios

 How to" install, configure and secure your monitoring server the most simply possible.

• Download the nagios and plugins
• Take care of the prerequisites
• Create user and group for nagios
• Install nagios
• Configure the web interface
• Compile and install nagios plugins
• Start Nagios
• Login to web interface

Download the nagios and plugins

from the website : http://www.nagios.org/download/core/thanks/

Take care of the prerequisites

yum install gcc gd

Create user and group for nagios

useradd nagios

groupadd nagios

usermod -G nagios nagios

usermod -G nagios apache

Install nagios

tar xvf nagios-3.x.x.tar.gz

cd nagios

/configure --with-command-group=nagios

make all

make install

make install-config

make install-commandmode

Configure the web interface.

make install-webconf

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

Compile and install nagios plugins

tar xvf nagios-plugins-1.4.xx.tar.gz

cd nagios-plugins

./configure --with-nagios-user=nagios --with-nagios-group=nagios

make

make install

Start Nagios

chkconfig --add nagios

chkconfig nagios on

command line

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

service nagios start

Login to web interface

http://localhost/nagios/

Configuration File located at /usr/local/nagios/etc/

• nagios.cfg – This is the primary Nagios configuration file where lot of global parameters that controls the nagios can be defined.
• cgi.cfg - This files has configuration information for nagios web interface.
• resource.cfg – If you have to pass some sensitive information (username, password etc.) to a plugin to monitor a specific service, you can define them here. This file is readable only by nagios user and group.

Following are the other configuration files under /usr/local/nagios/etc/objects directory:

• contacts.cfg: All the contacts who needs to be notified should be defined here. You can specify name, email address, what type of notifications they need to receive and what is the time period this particular contact should be receiving notifications etc.
• commands.cfg – All the commands to check services are defined here. You can use $HOSTNAME$ and $HOSTADDRESS$ macro on the command execution that will substitute the corresponding hostname or host ip-address automatically.
• timeperiods.cfg – Define the timeperiods. for e.g. if you want a service to be monitored only during the business hours, define a time period called businesshours and specify the hours that you would like to monitor.
• templates.cfg – Multiple host or service definition that has similar characteristics can use a template, where all the common characteristics can be defined. Use template is a time saver.
• localhost.cfg – Defines the monitoring for the local host. This is a sample configuration file that comes with nagios installation that you can use as a baseline to define other hosts that you would like to monitor.
• printer.cfg – Sample config file for printer
• switch.cfg – Sample config file for switch
• windows.cfg – Sample config file for a windows machine