Installation of Nagios Server on Centos

Nagios is one of the open source computer system and network monitoring software application.

Installation of Nagios server

Create nagios user account and set password

            [root@st-web manivel]# useradd -m nagios

            [root@st-web manivel]# passwd nagios

Changing password for user nagios.
New password:
BAD PASSWORD: it is based on a dictionary word
Retype new password:
passwd: all authentication tokens updated successfully.
[root@st-web manivel]#

Create a new group "nagcmd"

           [root@localhost html]# groupadd nagcmd

Add the "nagios" user and "apache" user to the "nagcmd" group

          [root@localhost html]# usermod -a  -G nagcmd nagios

          [root@localhost html]# usermod -a  -G nagcmd apache

Download Nagios and Nagios Plugins

Create a directory "nagios-store" for store downloads

         [root@localhost ~]# mkdir nagios-store

         [root@localhost ~]# cd  nagios-store

Download the Nagios and Nagios Plugins using "wget" command

 [root@localhost nagios-store]# wget http://sourceforge.net/projects/nagios/files/nagios-3.x/nagios-3.5.0/nagios-3.5.0.tar.gz/download

[root@localhost nagios-store]# wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.16.tar.gz

Extract, Compile and install the "Nagios"

[root@localhost nagios]# tar -xzf nagios-3.5.0.tar.gz

[root@localhost nagios]# cd nagios

[root@localhost nagios]# ./configure 

[root@localhost nagios]# make all

[root@localhost nagios]# make install

[root@localhost nagios]# make install-init

make install-init

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

[root@localhost nagios]# make install-commandmode

  make install-commandmode

     - This installs and configures permissions on the

       directory for holding the external command file

[root@localhost nagios]# make install-webconf

   make install-webconf

          - This installs the web interface

Extract, Compile and install the "Nagios Plugins"

[root@localhost nagios-store]#  tar -xzf nagios-plugins-1.4.16.tar.gz 

[root@localhost nagios-store]#  cd nagios-plugins-1.4.16

[root@localhost nagios-plugins-1.4.16]#  ./configure 

[root@localhost nagios-store]#  make && make install

Start the Nagios service

[root@localhost nagios-plugins-1.4.16]#  /etc/init.d/nagios  start

Starting nagios: done.

Nagios service automatically start when the system boots

[root@localhost nagios-plugins-1.4.16]# chkconfig nagios on

Verify the sample nagios configuration files

[root@localhost nagios-plugins-1.4.16]# /usr/local/nagios/bin/nagios  -v  /usr/local/nagios/etc/nagios.cfg

It should display without error like this

Nagios Core 3.5.0

Copyright (c) 2009-2011 Nagios Core Development Team and Community Contributors

Copyright (c) 1999-2009 Ethan Galstad

Last Modified: 03-15-2013

License: GPL

Website: http://www.nagios.org

Reading configuration data...

   Read main config file okay...

Processing object config file '/usr/local/nagios/etc/objects/commands.cfg'...

Processing object config file '/usr/local/nagios/etc/objects/contacts.cfg'...

Processing object config file '/usr/local/nagios/etc/objects/timeperiods.cfg'...

Processing object config file '/usr/local/nagios/etc/objects/templates.cfg'...

Processing object config file '/usr/local/nagios/etc/objects/localhost.cfg'...

   Read object config files okay...

Running pre-flight check on configuration data...

Checking services...

Checked 8 services.

Checking hosts...

Checked 1 hosts.

Checking host groups...

Checked 1 host groups.

Checking service groups...

Checked 0 service groups.

Checking contacts...

Checked 1 contacts.

Checking contact groups...

Checked 1 contact groups.

Checking service escalations...

Checked 0 service escalations.

Checking service dependencies...

Checked 0 service dependencies.

Checking host escalations...

Checked 0 host escalations.

Checking host dependencies...

Checked 0 host dependencies.

Checking commands...

Checked 24 commands.

Checking time periods...

Checked 5 time periods.

Checking for circular paths between hosts...

Checking for circular host and service dependencies...

Checking global event handlers...

Checking obsessive compulsive processor commands...

Checking misc settings...

Total Warnings: 0

Total Errors:   0

Things look okay - No serious problems were detected during the pre-flight check

[root@localhost nagios-plugins-1.4.16]# 

Modify SELinux and Firewall Settings

[root@localhost nagios-plugins-1.4.16]# getenforce 

Enforcing

[root@localhost nagios-plugins-1.4.16]# service iptables status

iptables: Firewall is not running.

Once firewall running then stop that

[root@localhost nagios-plugins-1.4.16]# service iptables stop

Change SELinux mode Enforcing to Permissive mode

[root@localhost nagios-plugins-1.4.16]# setenforce 0

If you want to permanently change this, then you need to change below configuration file and reboot your machine.

[root@localhost nagios-plugins-1.4.16]# vim /etc/selinux/config 

# This file controls the state of SELinux on the system.

# SELINUX= can take one of these three values:

#     enforcing - SELinux security policy is enforced.

#     permissive - SELinux prints warnings instead of enforcing.

#     disabled - No SELinux policy is loaded.

SELINUX=disabled

# SELINUXTYPE= can take one of these two values:

#     targeted - Targeted processes are protected,

#     mls - Multi Level Security protection.

SELINUXTYPE=targeted


Now restart the nagios service

[root@localhost nagios-plugins-1.4.16]#  /etc/init.d/nagios  restart

Web interface configuration

     [root@localhost nagios]# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
      New password: 
      Re-type new password: 
     Adding password for user nagiosadmin

     [root@localhost nagios]#

                username: nagiosadmin

Now restart the httpd service

       [root@localhost nagios]#  /etc/init.d/httpd  restart 
          

You can able to access nagios monitoring system through url with username and password

  http://10.118.248.52/nagios/   or   http://localhost/nagios/