🌃Add a New Host For Monitoring Nagios (DB-Instance)

Configuration

DB-Instance

Install Prerequirement

apt update
apt install -y autoconf gcc libmcrypt-dev make libssl-dev dc build-essential gettext libdbd-mysql-perl

Download Source

cd /tmp
wget --no-check-certificate -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.4.6.tar.gz
tar zxf nagios-plugins.tar.gz

Install and compile

cd nagios-plugins-release-2.4.6/
./tools/setup
./configure
make
make install

Install NRPE Daemon on Agent

apt install -y autoconf automake gcc libc6 libmcrypt-dev make libssl-dev

Download NRPE (nrpe-4.1.0)

cd /tmp
wget --no-check-certificate -O nagios-nrpe.tar.gz  https://github.com/NagiosEnterprises/nrpe/releases/download/nrpe-4.1.0/nrpe-4.1.0.tar.gz
tar zxf nagios-nrpe.tar.gz 

Configure script and compile NRPE

cd nrpe-4.1.0/
./configure --enable-command-args
sudo make all
sudo make install-groups-users
sudo make install
sudo make install-config
sudo make install-init

Update Agent NRPE Configuration\

nano /usr/local/nagios/etc/nrpe.cfg

line 61 : add ip 0.0.0.0 line 106 : add the NMS Nagios private server ip line 306 : add the script

## check_nrpe script for DB-Instance

command[check_root]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /
command[check_ping]=/usr/local/nagios/libexec/check_ping -H <ip-private-host> -w 100.0,20% -c 500.0,60% -p 5
command[check_ssh]=/usr/local/nagios/libexec/check_ssh -4 <ip-private-host> 
#command[check_http]=/usr/local/nagios/libexec/check_http <ip-private-host> 
command[check_apt]=/usr/local/nagios/libexec/check_apt

Start service NRPE

systemctl start nrpe.service
systemctl enable nrpe.service
systemctl status nrpe.service

Install mysql_health Plugin

cd
wget https://labs.consol.de/assets/downloads/nagios/check_mysql_health-2.2.2.tar.gz
tar xzf check_mysql_health-2.2.2.tar.gz
cd check_mysql_health-2.2.2/
./configure
make
cp plugins-scripts/check_mysql_health /usr/local/nagios/libexec

Create Database

mysql -u root -p

create user 'nagiosrizwan'@'%' identified by 'pass123';
GRANT SELECT, PROCESS, SUPER ON  *.* to 'nagiosrizwan'@'%';
flush privileges;

NMS-Nagios

Install pre-requisites package

apt -y install libdbd-mysql-perl

Install mysql_health Plugin

cd
wget https://labs.consol.de/assets/downloads/nagios/check_mysql_health-2.2.2.tar.gz
tar xzf check_mysql_health-2.2.2.tar.gz
cd check_mysql_health-2.2.2/
./configure
make
cp plugins-scripts/check_mysql_health /usr/local/nagios/libexec

Test the check_mysql_health plugin

cd plugins-scripts/
./check_mysql_health -H <ip-private-DB> --user <db-user> --password <db-pass> --mode uptime

Edit File commands.cfg

nano /usr/local/nagios/etc/objects/commands.cfg

define command{
     command_name check_mysql_health
     command_line $USER1$/check_mysql_health -H $ARG1$ --port $ARG2$ --username $ARG3$ --password $ARG4$ --mode $ARG5$
}

Add the following script to the bottom line.

Edit file hosts.cfg

nano /usr/local/nagios/etc/hosts.cfg

## Define Host - DB Instance
define host {
     use linux-server ; Name of host template to use
; This host definition will inherit all variables that are defined
; in (or inherited by) the linux-server host template definition.
     host_name <linux-host2>
     alias mysql_server
     address <ip-private-db>
     notification_interval 1
     notification_options d,u,r,f,s
     check_interval 1
     retry_interval 1
     contact_groups admins
     notifications_enabled 1
     notification_period 24x7
}

<linux-host2> = db-instance
<ip-private-db> = 10.10.2.196

Edit File services.cfg

nano /usr/local/nagios/etc/services.cfg

define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     Root
        check_command           check_nrpe!check_root
        }

define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     APT
        check_command           check_nrpe!check_apt
        }



define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     CPU Load
        check_command           check_nrpe!check_load
        }

define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     Total Processes
        check_command           check_nrpe!check_total_procs
        }

define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     Current Users
        check_command           check_nrpe!check_users
        }

define service{
        use                     generic-service
        host_name               host-linux1, host-linux2
        service_description     SSH Monitoring
        check_command           check_nrpe!check_ssh
        }

add the db-instance host_name next to the web server hostname so that check_nrpe is carried out simultaneously on two linux_hosts.

host-linux1 = webserver host-linux2 = db-instance

define service { 
 host_name <linux-host2>
 service_description MySQL Connections
 check_command check_mysql_health!<ipadd-db>!3306!<user-db>!<pass-db>!threads-connected
 notification_interval 1
 notification_options w,u,c,r,f,s
 check_interval 1
 retry_interval 1
 contact_groups admins
 notifications_enabled 1
 notification_period 24x7
 max_check_attempts 3
 check_period 24x7
 }

define service { 
 host_name <host_name-db>
 service_description MySQL Uptime
 check_command check_mysql_health!<ipadd-db>!3306!<user-db>!<pass-db>!uptime
 check_interval 1
 retry_interval 1
 contact_groups admins
 notifications_enabled 1
 notification_period 24x7
 notification_options w,u,c,r,f,s
 notification_interval 1
 max_check_attempts 3
 check_period 24x7
}

host-name-db = db-instance

ip-addr-db = 10.10.2.196

user-db = nagiosrizwan

pass-db = pass123

Check the Nagios configuration

Check the Nagios configuration file to see if there are errors.

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

Restart Service Nagios

systemctl restart nagios.service

---

Configuration is Completed

Open Browser

http://<ip-addr-pub-nagios>/nagios

username : nagiosadmin
password : nagiosadmin