How to install and configure Nagios Monitoring tool in redhat linux rhel5 or centos

This article will help you to install and configure Nagios monitoring tool in redhat linux or other redhat distributions like fedora, centos etc.

Nagios Installation :
Installing packages. Apache, PHP, GCC & GD


Installing Apache web server:
#yum -y install httpd*
set hostname in FQDN
#service httpd on


Installing PHP, GCC and GD:
#yum -y install php*
#yum -y install gcc*
#yum -y install gd*

Getting the package:
Get the latest packages from net. Mov it to some directory and untar them.

#wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.0.tar.gz
#mv nagios-3.2.0.tar.gz  /usr/local/src
#tar xvf nagios-3.2.0.tar.gz

#wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.14.tar.gz
#mv nagios-plugins-1.4.14.tar.gz/usr/local/src
#tar xvf nagios-plugins-1.4.14.tar.gz

Adding nagios user and setting password for that user:
#useradd nagios
#passwd nagios
usermod -a -G nagios apache              //To permit the commands through web interface.

Configuration of Nagios:
cd /usr/local/src/nagios-3.2.0

./configure
make all
make install
make install-init
make install-config
make install-commandmode
make install-webconf

Admin account setting for nagios:
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin          /passwd  for web interface
give passwd
service httpd restart

Nagios Plugin installation:
install nagios - pluggin

cd /usr/local/src/nagios-plugins-1.4.14
./configure
make
make install

Creating entry in /etc/init.d/:
chkconfig --add nagios
chkconfig nagios on

Checking the configuration:
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Nagios Alert Plugin - Mozilla Addon:
Name : Nagios Checker
[give name and url]

Configuring remotehost in nagios:
cp /usr/local/nagios/etc/objects/localhost.cfg  /usr/local/nagios/etc/objects/remotehost.cfg
[comment the hostgroup entries in order to prevent duplicate entries]
[change the localhost entries to the remote machine hostname and IP address.]