How to Install Nagios on Ubuntu 16.04 LTS

https://github.com/rkidambi11/Docker-Nagios.git

docker pull jasonrivers/nagios:latest

Running

Run with the example configuration with the following:

docker run --name nagios4 -p 0.0.0.0:8080:80 jasonrivers/nagios:latest

alternatively you can use external Nagios configuration & log data with the following:

docker run --name nagios4  \

  -v /path-to-nagios/etc/:/opt/nagios/etc/ \

  -v /path-to-nagios/var:/opt/nagios/var/ \

  -v /path-to-custom-plugins:/opt/Custom-Nagios-Plugins \

  -v /path-to-nagiosgraph-var:/opt/nagiosgraph/var \

  -v /path-to-nagiosgraph-etc:/opt/nagiosgraph/etc \

  -p 0.0.0.0:8080:80 jasonrivers/nagios:latest

Note: The path for the custom plugins will be /opt/Custom-Nagios-Plugins, you will need to reference this directory in your configuration scripts.

Credentials:

The default credentials for the web interface is nagiosadmin / nagios

Step 1– Configure Nagios (Server and Remote HOST)

Now login into your Nagios Monitoring Server. Here you will need to do following things:

docker exec -it nagios4 /bin/bash
Install the check_nrpe plugin.
Create a Nagios command definition using the check_nrpe plugin.
Create Nagios host and add service definitions for monitoring the remote Linux host.

Step 1: Install NRPE Plugin

docker exec -it nagios4 /bin/bash

# [root@nagiosserver] sudo apt-get update

[root@nagiosserver] sudo apt-get install nagios-nrpe-server nagios-plugins

OR

[root@nagiosserver] sudo ap-get update

[root@nagiosserver] wget https://www.nagios-plugins.org/download/nagios-plugins-2.1.2.tar.gz

[root@nagiosserver] tar -xvf nagios-plugins-2.1.2.tar.gz

[root@nagiosserver]  ls -ltr

[root@nagiosserver] cd nagios-plugins-2.1.2

[root@nagiosserver] ls -ltr

[root@nagiosserver] ./configure

[root@nagiosserver] make all

[root@nagiosserver] find / -name check_nrpe

Step 2–Configure NRPE (Only on remote host)

In NRPE configuration, first we need to nrpe to which nagios servers it accepts requests, For example your nagios server ip is 192.168.1.100, then add this ip to allowed hosts list. Edit NRPE configuration file /etc/nagios/nrpe.cfg and make changes like

/etc/nagios/nrpe.cfg -- vi to this file.

 allowed_hosts=127.0.0.1, 192.168.1.100  --->> ### It should be in client machine and allow nagios server ip.

we can add more Nagios servers in allowed hosts by comma separated list.

Now restart NRPE service. Now its ready to listen to requests from Nagios server

sudo /etc/init.d/nagios-nrpe-server restart

Step 3 – Verify Connection from Nagios Server

Let’s verify the connection between the Nagios server and NRPE client machine. Login to your Nagios server and check the Nagios server can communicate with NRPE service properly.

Use check_nrpe command on Nagios server under plugins directory. The command will be like as below here 192.168.1.11 is the IP address of client machine.

/opt/nagios/libexec/check_nrpe -H 10.128.0.15  ## client IP

NRPE v2.15   #### You will get this response from client.

The output “NRPE v2.15” shows that the Nagios server successfully communicated with NRPE.

Step 4 – Add Check Commands in NRPE

All the services check commands with the nagios plugins packages, which is by default installed in /usr/lib/nagios/plugins/ for 32 bit systems. Default installation adds few commands in configuration file. Add more commands as per your requirements like below

vim /etc/nagios/nrpe.cfg  ### this is from master.

/etc/nagios/nrpe.cfg

command[check_users]=/usr/lib/nagios/plugins/check_users -w 5 -c 10

command[check_load]=/usr/lib/nagios/plugins/check_load -w 15,10,5 -c 30,25,20

command[check_hda1]=/usr/lib/nagios/plugins/check_disk -w 20% -c 10% -p /dev/hda1

command[check_zombie_procs]=/usr/lib/nagios/plugins/check_procs -w 5 -c 10 -s Z

command[check_total_procs]=/usr/lib/nagios/plugins/check_procs -w 150 -c 200

Step 5 – Start/Stop NRPE Service (On Nagios)

Use following commands to start, stop or restart NRPE service. Each time we make any changes in configuration file required to restart service

sudo /etc/init.d/nagios-nrpe-server stop

sudo /etc/init.d/nagios-nrpe-server start

sudo /etc/init.d/nagios-nrpe-server restart

Note : If you are not able to see the hosts and service stop and start the nexus container. Also please allow 5666 port from AWS security group or GCP firewall group.

STEP6-

Adding Remote Linux Host to Nagios Monitoring Server

To add a remote host you need to create a two new files “hosts.cfg” and “services.cfg” under “/opt/nagios/etc/” location.

[root@nagiosserver]# touch hosts.cfg

[root@nagiosserver]# touch services.cfg

STEP7:-

Now add these two files to main Nagios configuration file. Open nagios.cfg file with any editor.

[root@nagiosserver]# vi /opt/nagios/etc/nagios.cfg

# You can specify individual object config files as shown below:

cfg_file=/opt/nagios/etc/hosts.cfg

cfg_file=/opt/nagios/etc/services.cfg

STEP8:-

Now open hosts.cfg file and add the default host template name and define remote hosts as shown below. Make sure to replace host_name, alias and address with your remote host server details.

[root@nagiosserver]# vi /opt/nagios/etc/hosts.cfg

## Default Linux Host Template ##

define host{

name                            linux-box               ; Name of this template

use                             generic-host            ; Inherit default values

check_period                    24x7

check_interval                  5

retry_interval                  1

max_check_attempts              10

check_command                   check-host-alive

notification_period             24x7

notification_interval           30

notification_options            d,r

contact_groups                  admins

register                        0                       ; DONT REGISTER THIS - ITS A TEMPLATE

## Default

define host{

use                             linux-box               ; Inherit default values from a template

host_name                       tecmint            ; The name we're giving to this server

alias                           CentOS 6                ; A longer name for the server

address                         5.175.142.66            ; IP address of Remote Linux host

STEP9:-

Next open services.cfg file add the following services to be monitored.

define service{

        use                     generic-service

        host_name               tecmint

        service_description     CPU Load

        check_command           check_nrpe!check_load

define service{

        use                     generic-service

        host_name               tecmint

        service_description     Total Processes

        check_command           check_nrpe!check_total_procs

define service{

        use                     generic-service

        host_name               tecmint

        service_description     Current Users

        check_command           check_nrpe!check_users

define service{

        use                     generic-service

        host_name               tecmint

        service_description     SSH Monitoring

        check_command           check_nrpe!check_ssh

define service{

        use                     generic-service

        host_name               tecmint

        service_description     FTP Monitoring

        check_command           check_nrpe!check_ftp

STEP10 :-

Now NRPE command definition needs to be created in commands.cfg file.

[root@nagiosserver]# vi /opt/nagios/etc/objects/commands.cfg

STEP11:-

Add the following NRPE command definition at the bottom of the file

###############################################################################

# NRPE CHECK COMMAND

# Command to use NRPE to check remote host systems

###############################################################################

define command{

        command_name check_nrpe

        command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

Finally, verify Nagios Configuration files for any errors.

/opt/nagios/bin/nagios -v /opt/nagios/etc/nagios.cfg

URL Details : https://www.tecmint.com/how-to-add-linux-host-to-nagios-monitoring-server/

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