In this tutorial we will learn about how to install nagios 4.0.2 in Linux using tarball.Nagios is one of the famous and very robust Monitoring Server.The installation has been done in minimal installed CentOS 6.4.Recently Nagios team has released its much awaited 4.x version.The installation steps is applicable to other Nagios version also.

Details of Server:

Operating System : CentOS 6.4
Arch : x86_64
Nagios Version: 4.0.2
My Server IP address: 192.168.1.6

IPtables is stopped /etc/init.d/iptables stop
SELINUX is disabled

Follow the given below steps to install Nagios 4.x

Login to your Server by using root user

Step 1 : Install wget package for downloading the Nagios package through command line.

yum install wget

Step 2: Download Nagios package. You will get the Nagios package in tar format.

wget http://nchc.dl.sourceforge.net/project/nagios/nagios-4.x/nagios-4.0.2/nagios-4.0.2.tar.gz

Step 3: Install the dependencies and apache server (httpd)

yum install   httpd php  gd gd-devel gcc glibc glibc-common openssl perl perl-devel make

Step 4: Now create the user and group for Nagios installation

useradd nagios
groupadd nagcmd
usermod -a -G nagcmd nagios

Step 5: Now extract the downloaded file. Here I downloaded the file called nagios-4.0.2.tar.gz (see in Step 2)

tar -xvzf nagios-4.0.2.tar.gz

Step 6: After extracting the downloaded nagios package.It will extract out the Nagios directory. Here we downloaded the package nagios-4.0.2.tar.gz, after extraction I got directory called nagios-4.0.2 .

Now change to extracted out Nagios directory . On using ls -la command you will see many files inside nagios-4.0.2 directory,these all files and directory will be used in installation. So we are going to compile the Nagios package.

cd nagios-4.0.2

./configure --with-command-group=nagcmd
make all
make install
make install-init
make install-config
make install-commandmode
make install-webconf

After running all above commands if you find no error now move to next step.

Now copy the eventhandlers directory into /usr/local/nagios/libexec/ as well as change ownership and group of this copied directory

cp -rvf contrib/eventhandlers/ /usr/local/nagios/libexec/

chown -R nagios:nagios /usr/local/nagios/libexec/eventhandlers

Step 7: Now we will check nagios.cfg file configuration. Use the given below command for it. It should not show any error otherwise nagios service can not be started. You can use this command whenever you do any configuration change in nagios.cfg file.

Syntax: /usr/local/nagios/bin/nagios -v

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

Step 8: Now we set the htpasswd apache authentication for user nagiosadmin. This same username and password will be used when you will try to open nagios dashboard.

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

Step 9: Start the apache and nagios service

/etc/init.d/nagios start
/etc/init.d/httpd start

to bydefault service run in runlevel 3,4,5 use below given command

chkconfig nagios on
chkconfig httpd on

Step 10: Change the permission of file /usr/local/nagios/var/rw/nagios.cmd .(reference from this troubleshooting post)

chmod 666 /usr/local/nagios/var/rw/nagios.cmd

Install Nagios plugin from source

Now in this section we will install nagios plugin.Later you can also add some more nagios as per your requirement. I downloaded the plugin from this link

Follow the given below steps for nagios plugin installation

cd ~

wget https://www.nagios-plugins.org/download/nagios-plugins-1.5.tar.gz

tar -xvzf nagios-plugins-1.5.tar.gz

cd nagios-plugins-1.5

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

make

make install 

Step 11: Now time to go to Nagios dashboard. Open the web browser in address link type your server ip address appending /nagios.
Now give username nagiosadmin password which you have set in Step 9

My Nagios server ip address is 192.168.1.6 hence replace the ip address with your server ip

http://192.168.1.6/nagios

After login you will get your Nagios dashboard (See the screenshot)