Nagios Core

Nagios

Nagios is an open source software light-weight designed to monitor system, networks and infrastructure, its light weight allow us to install it in a raspberry.

There are several version but in this tutorial we go for the Nagios Core

1. Prepare Raspberry¶

Update the system.

sudo apt updates
sudo apt full-upgrade

2. Install the packages need it for Nagios

sudo apt install -y autoconf build-essential wget unzip apache2 apache2-utils php libgd-dev snmp libnet-snmp-perl gettext libssl-dev wget bc gawk dc libmcrypt-dev

2. Download and compiling Nagios¶

1. Move to a temporal directory `/tmp` were wi later will download the Nagios source code.¶

cd /tmp

2. Download the Nagios source code¶

wget -O nagios.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.6.tar.gz

I had an issue with SSL those i download it normally and i move it to the directory manually

3. Extract the files¶

1	`tar xzf nagios.tar.gz`

4. Move to the directory and prepare for compilation¶

cd /tmp/nagioscore-nagios-4.4.6/
./configure --with-httpd-conf=/etc/apache2/sites-enabled

5. Compile Nagios¶

1	`make all`

3. Settings up Nagios on the Raspberry¶

1. Create users and groups with the `make` command¶

sudo make install-groups-users
sudo usermod -a -G nagios www-data

2. Installed the binaries to the system using the command bellow¶

1	`sudo make install`

3. With the `make` command we install the Nagios service and make it start at boot¶

this command install the Nagios core deamon

1	`sudo make install-daemoninit`

4. we set up the external command directory¶

1	`sudo make install-commandmode`

5. Copy a sample configuration file using `make`¶

this file is important without it the software wont run

1	`sudo make install-config`

6. now configure the apache server or to install the configuration for the apache¶

sudo make install-webconf
sudo a2enmod rewrite
sudo a2enmod cgi

7. Now we create an apache user that we will use to access the Nagios interface¶

The following command will create a user called nagiosadmin. You will be asked to specify a password for this user.

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

The user must be called nagiosadmin to satisfy the default configuration of Nagios.

4. Starting Nagios on Raspberry¶

1. Restart the Apache server¶

sudo systemctl restart apache2

2. Enable NAgios service and start it up by running the following two commands¶

sudo systemctl enable nagios
sudo systemctl start nagios

By enabling the service, we will be allowing Nagios to start up at boot on your Raspberry Pi.

3. Verify that Nagios has started on your Raspberry Pi by running the following command.¶

sudo systemctl status nagios

If everything is working as intended, you should see the following text be outputted to the terminal.

Active: active (running)

This text tells us that the service is active and is currently running.

5. Installing the Nagios Plug-ins¶

In this section, we will be showing you how to install these Nagios plugins on your Raspberry Pi.

1. First change into our /tmp directory.¶

cd /tmp

2. Now that we are in the /tmp directory, we can download the Nagios plugins by running the command below.¶

wget -O nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/releases/download/release-2.3.3/nagios-plugins-2.3.3.tar.gz

3. Now extract the plugin source code to our current directory by using the following command.¶

1	`tar zxf nagios-plugins.tar.gz`

4. Our next step is to change into our newly created directory and configure the plugins for compilation.¶

1 2	`cd /tmp/nagios-plugins-2.3.3 ./configure`

4. Once the configuration process has completed, we can compile the Nagios plugins by running the following command.¶

make

Depending on your Raspberry Pi, this process can take some time. However, it should be a lot faster than compiling the base Nagios code.

5. Finish up this process by installing the Nagios plugins by running the following command.¶

1	`sudo make install`

6. To make sure Nagios loads in the new plugins, restart the software by running the command below.¶

sudo systemctl restart nagios

6. Connecting the Nagios Web interface¶

We can access the UI by

1	`http://[IPADDRESS]/nagios`

You can retrieve your Raspberry Pi’s local IP address by running the following command.

1	`hostname -I`

7. Adding Devices to Nagios¶

To add host we will need to create a configuration file that later Nagios will read.

1. Navigate to `object` configuration folder for Nagios¶

this is a default folder that contain sample configuration files we can check the file to get an idea

1	`cd /usr/local/nagios/etc/objects`

2. Now lets create a configuration file¶

We can use a name pimylifeuphost.cfg

1	`sudo nano pimylifeuphost.cfg`

3. within the file we can enter the following¶

define host {
    use                     linux-server            ; Host group to use
    host_name               Pi My Life Up Host      ; Name of this host
    alias                   pimylifeuphost          ; Alias
    address                 [YOURHOSTIPADDRESS]     ; IP Address
}

to save ctrl + x follow by y and enter

4. We need to modify the Nagios file to be able to read the new host¶

1	`sudo nano /usr/local/nagios/etc/nagios.cfg`

5. within the file we need to do changes¶

Find

1	`cfg_file=/usr/local/nagios/etc/objects/templates.cf`

add Bellow

1	`cfg_file=/usr/local/nagios/etc/objects/pimylifeuphost.cfg`

Restart Nagios

sudo systemctl restart nagios

For now we are making a ping check and nothing else, for more specialties test we need to configure the services

8. Adding Service to Nagios¶

This example we will add check_http and Check_ssh

1. We need to modify the host configuration created earlier¶

define service {
    use                     local-service
    host_name               Pi My Life Up Host
    service_description     SSH
    check_command           check_ssh
}

define service {
    use                     local-service
    host_name               Pi My Life Up Host
    service_description     HTTP
    check_command           check_http
}

2. We need to check if the configuration made is correct¶

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

If everything is okay we will see Things look okay

Navios

Now we restart Nagios

sudo systemctl restart nagios