How to install Nagios Core 4.0.0. on CentOS 6

[vinayakk]

Nagios is an open source computer system monitoring, network monitoring and infrastructure monitoring software application. Nagios offers monitoring and alerting services for servers, switches, applications, and services. It alerts the users when things go wrong and alerts them a second time when the problem has been resolved.

Installing Nagios 4.0.1 and Nagios Plugin 1.5

Step 1: Install Required Dependencies

We need to install Apache, PHP and some libraries like gcc, glibc, glibc-common and GD libraries and its development libraries before installing Nagios 4.0.1 with source. And to do so we can use yum default package installer.

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# yum install -y httpd php gcc glibc glibc-common gd gd-devel make net-snmp
Step 2: Create Nagios User and Group

Create a new nagios user and nagcmd group account and set a password.

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# useradd nagios
# groupadd nagcmd
Next, add both the nagios user and the apache user to the nagcmd group.

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# usermod -G nagcmd nagios
# usermod -G nagcmd apache
Step 3: Download Nagios Core 4.0.1 and Nagios Plugin 1.5

Create a directory for your Nagios installation and all its future downloads.

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# mkdir /root/nagios
# cd /root/nagios
Now download latest Nagios Core 4.0.1 and Nagios plugins 1.5 packages with wget command.

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# wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-4.0.1.tar.gz
# wget https://www.nagios-plugins.org/download/nagios-plugins-1.5.tar.gz
Step 4: Extract Nagios Core and its Plugins

We need to extract downloaded package with tar command as follows.

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# tar –xvf nagios-4.0.1.tar.gz
# tar –xvf nagios-plugins-1.5.tar.gz
When you extract these tarballs with tar command, two new folders will appear in that directory.

Configure Nagios Core

Now, first we will configure Nagios Core and to do so we need to go to Nagios directory and run configure file and if everything goes fine, it will show the output in the end as sample output. Please see below.

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# cd nagios-4.0.1
# ./configure --with-command-group=nagcmd
Sample output:

Nagios executable:  nagios
        Nagios user/group:  nagios,nagios
       Command user/group:  nagios,nagcmd
             Event Broker:  yes
        Install ${prefix}:  /usr/local/nagios
    Install ${includedir}:  /usr/local/nagios/include/nagios
                Lock file:  ${prefix}/var/nagios.lock
   Check result directory:  ${prefix}/var/spool/checkresults
           Init directory:  /etc/rc.d/init.d
  Apache conf.d directory:  /etc/httpd/conf.d
             Mail program:  /bin/mail
                  Host OS:  linux-gnu

 Web Interface Options:
 ------------------------
                 HTML URL:  http://localhost/nagios/
                  CGI URL:  http://localhost/nagios/cgi-bin/
 Traceroute (used by WAP):  /bin/traceroute


Review the options above for accuracy.  If they look okay,
type 'make all' to compile the main program and CGIs.

Now, after configuring we need to Compile and install all the binaries with make command and make install command will install all the needed libraries in your machine and we can proceed further.

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# make all
# make install
Sample output:

*** Main program, CGIs and HTML files installed ***

You can continue with installing Nagios as follows (type 'make'
without any arguments for a list of all possible options):

  make install-init
     - This installs the init script in /etc/rc.d/init.d

  make install-commandmode
     - This installs and configures permissions on the
       directory for holding the external command file

  make install-config
     - This installs sample config files in /usr/local/nagios/etc

Following command will install the init scripts for Nagios.

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# make install-init
To make nagios work from command line we need to install command-mode.

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# make install-commandmode
Next, install sample nagios files, please run following command.

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# make install-config
Sample output:

/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/etc
/usr/bin/install -c -m 775 -o nagios -g nagios -d /usr/local/nagios/etc/objects
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/nagios.cfg /usr/local/nagios/etc/nagios.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/cgi.cfg /usr/local/nagios/etc/cgi.cfg
/usr/bin/install -c -b -m 660 -o nagios -g nagios sample-config/resource.cfg /usr/local/nagios/etc/resource.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/templates.cfg /usr/local/nagios/etc/objects/templates.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/commands.cfg /usr/local/nagios/etc/objects/commands.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/contacts.cfg /usr/local/nagios/etc/objects/contacts.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/timeperiods.cfg /usr/local/nagios/etc/objects/timeperiods.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/localhost.cfg /usr/local/nagios/etc/objects/localhost.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/windows.cfg /usr/local/nagios/etc/objects/windows.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/printer.cfg /usr/local/nagios/etc/objects/printer.cfg
/usr/bin/install -c -b -m 664 -o nagios -g nagios sample-config/template-object/switch.cfg /usr/local/nagios/etc/objects/switch.cfg

*** Config files installed ***

Remember, these are *SAMPLE* config files.  You'll need to read
the documentation for more information on how to actually define
services, hosts, etc. to fit your particular needs.


Step 5: Customizing Nagios Configuration

Open the “contacts.cfg” file with your choice of editor and set the email address associated with the nagiosadmin contact definition to receiving email alerts.

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# vi /usr/local/nagios/etc/objects/contacts.cfg
Sample Output

###############################################################################
###############################################################################
#
# CONTACTS
#
###############################################################################
###############################################################################

# Just one contact defined by default - the Nagios admin (that's you)
# This contact definition inherits a lot of default values from the 'generic-contact'
# template which is defined elsewhere.

define contact{
       contact_name                    nagiosadmin             ; Short name of user
       use                             generic-contact         ; Inherit default values from generic-contact template (defined above)
       alias                           Nagios Admin            ; Full name of user

       email                           tecmint@tecmint.com     ; *** CHANGE THIS TO YOUR EMAIL ADDRESS ****
       }


Step 6: Install and Configure Web Interface for Nagios

We are done with all configuration in the backend, now we will configure Web Interface For Nagios with following command. The below command will Configure Web interface for Nagios and a web admin user will be created “nagiosadmin”.

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# make install-webconf
In this step, we will be creating a password for “nagiosadmin”. After executing this command, please provide a password twice and keep it remember because this password will be used when you login in the Nagios Web interface.

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# htpasswd -s -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
New password:
Re-type new password:
Adding password for user nagiosadmin
Restart Apache to make the new settings take effect.

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# service httpd start

Step 7: Compile and Install Nagios Plugin

We have downloaded nagios plugins in /root/nagios, Go there and configure and install it as directed below.

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# cd /root/nagios
# cd nagios-plugins-1.5
# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
# make
# make install

Step 8: Verify Nagios Configuration Files

Now we are all done with Nagios configuration and its time to verify it and to do so please insert following command. If everything goes smooth it will show up similar to below output.

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# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Sample Output

/usr/bin/install -c -m 644 sample-config/httpd.conf /etc/httpd/conf.d/nagios.conf

*** Nagios/Apache conf file installed ***

 /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
...
...
Total Warnings: 0
Total Errors:   0


Step 9: Add Nagios Services to System Startup

To make Nagios work across reboots, we need to add nagios and httpd with chkconfig command.

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# chkconfig --add nagios
# chkconfig --level 35 nagios on
# chkconfig --add httpd
# chkconfig --level 35 httpd on
Restart Nagios to make the new settings take effect.

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# service nagios start
Step 10: Login to the Nagios Web Interface

Your nagios is ready to work, please open it in your browser with “http://Your-server-IP-address/nagios” or “http://FQDN/nagios” and Provide the username “nagiosadmin” and password.