How To Install and Configure Nagios in Debian

Nagios is a monitoring solution for complex IT infrastructures, Nagios is easy to implement and can be extended by custom-modules, called plugins. In this howto I explain howto install Nagios on a CentOS host and make the configuration for it. 


Installing Package


root@atik:~# apt-get install nagios3

Confirmation password for user “nagiosadmin”

 

Adding Host Template


root@atik:~# cd /etc/nagios3/conf.d/
root@atik:/etc/nagios3/conf.d# cp generic-host_nagios2.cfg linux-server.cfg


Edit linux-server.cfg below

root@atik:/etc/nagios3/conf.d# vim linux-server.cfg

define host{

name     linux-server 

notifications_enabled  1

event_handler_enabled  1

flap_detection_enabled  1

failure_prediction_enabled 1

process_perf_data  1

retain_status_information 1

retain_nonstatus_information 1

check_command     example-host-check ; the script to be used while checkingcheck_interval                  3   ; the interval between consecutive checksmax_check_attempts              3   ; number of rechecking before generating email alertsnotification_interval           0

notification_period             24×7

notification_options  d,u,r

contact_groups   admins ; the group where emails will be sentregister                        0

}

Adding Host below

root@atik:/etc/nagios3/conf.d# cp localhost_nagios2.cfg example.cfg

root@atik:/etc/nagios3/conf.d# vim example.cfg

# Host 1

define host{

use   linux-server     ; Name of host template to use

host_name               our-server  ; The hostname to be used by nagios

alias                   our-server

address                 10.10.101.23  ; The IP address of the host

}

Host Group Definition

root@atik:/etc/nagios3/conf.d# vim hostgroups_nagios2.cfg

definehostgroup {

hostgroup_name  linux-server    ; the name of the host group

alias   Linux Servers

members   our-server      ; comma separated list of members

}

Finally, a dry run is initiated to check whether there are any configuration errors. If there are no errors, Nagios can be (re)started safely.

root@atik:~# nagios –v /etc/nagios3/nagios.cfg

root@atik:~# service nagios3 restart

Access Nagios after Configuration

Now you are ready to use Nagios.

Nagios can be accessed by opening the URL http://IP/nagios3 in case of Ubuntu/Debian.

e.g. http://10.10.101.23/nagios3

The user “nagiosadmin” needs to be authenticated to access the page.

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