---
title: Configuring a Nagios monitoring system on Scaleway
description: How to deploy Nagios monitoring on Scaleway.
tags: Nagios monitoring Apache
products:
  - instances
  - elastic-metal
dates:
  validation: 2025-04-01
  posted: 2018-06-19
  validation_frequency: 12
difficulty: beginner
usecase:
  - monitoring
ecosystem:
  - third-party
---
import Requirements from '@macros/iam/requirements.mdx'


Monitoring your resources is an indispensable building block for the success of your SaaS or e-commerce application. An unnoticed system failure can have serious financial consequences and negatively impact your image.
Therefore, you will learn by following this tutorial how to install and configure a [Nagios](https://www.nagios.org/) monitoring application with an Apache web server to monitor your servers.
It is an open-source monitoring system that can automatically alert you in case of a server dysfunction.

<Requirements />

- A Scaleway account logged into the [console](https://console.scaleway.com)
- [Owner](/iam/concepts/#owner) status or [IAM permissions](/iam/concepts/#permission) allowing you to perform actions in the intended Organization
- An [SSH key](/organizations-and-projects/how-to/create-ssh-key/)
- At least 2 [Instances](/instances/how-to/create-an-instance/) or 2 [Elastic Metal servers](/elastic-metal/how-to/create-server/)

<Message type="note">
  The commands in this guide are intended for a Debian-based system. Adjust package manager commands accordingly if you're using a different Linux distribution.
</Message>

## Installing Nagios Core

1. Update the system and install required packages:
   ```bash
   sudo apt update && sudo apt upgrade -y
   sudo apt install -y wget build-essential apache2 php libapache2-mod-php php-gd libgd-dev unzip
   ```

2. Create a user and group for Nagios:
   ```bash
   sudo useradd nagios
   sudo groupadd nagcmd
   sudo usermod -a -G nagcmd nagios
   sudo usermod -a -G nagcmd www-data
   ```

3. Download and extract Nagios Core:
   ```bash
   cd /tmp
   wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.5.9.tar.gz
   tar -xzf nagios-4.5.9.tar.gz
   cd nagios-4.5.9
   ```

4. Compile and install Nagios Core:
   ```bash
   ./configure --with-nagios-group=nagios --with-command-group=nagcmd
   make all
   sudo make install
   sudo make install-commandmode
   sudo make install-init
   sudo make install-config
   ```

## Installing Nagios plugins

Nagios plugins are essential for monitoring various services.

1. Install dependencies:
   ```bash
   sudo apt install -y libssl-dev
   ```

2. Download and extract Nagios plugins:
   ```bash
   cd /tmp
   wget https://nagios-plugins.org/download/nagios-plugins-2.4.11.tar.gz
   tar -xzf nagios-plugins-2.4.11.tar.gz
   cd nagios-plugins-2.4.11
   ```


3. Compile and install the plugins:
   ```bash
   ./configure --with-nagios-user=nagios --with-nagios-group=nagios
   make
   sudo make install
   ```

## Configuring Nagios

1. Configure the Nagios web interface:
   ```bash
   sudo make install-webconf
   sudo a2enmod rewrite
   sudo a2enmod cgi
   ```

2. Create an administrative user for the web interface:
   ```bash
   sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
   ```

   You will be prompted to set a password for the `nagiosadmin` user.

3. Restart Apache to apply changes:
   ```bash
   sudo systemctl restart apache2
   ```

4. Verify the Nagios configuration:
   ```bash
   sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
   ```

   Ensure there are no errors before proceeding.

5. Enable and start Nagios service:
   ```bash
   sudo systemctl enable nagios
   sudo systemctl start nagios
   ```


## Accessing the Nagios web interface

You can now access the Nagios web interface by navigating to `http://your.server.ip.address/nagios` in your web browser. Log in with the `nagiosadmin` user and the password you set earlier.

## Monitoring remote servers with NCPA

The Nagios Cross-Platform Agent (NCPA) is a versatile agent that allows you to monitor remote systems. It's a modern alternative to NRPE and supports various platforms.

On the remote server:

1. Download and install NCPA:
   ```bash
   cd /tmp
   wget https://assets.nagios.com/downloads/ncpa3/ncpa-latest-1.amd64.deb
   sudo dpkg -i ncpa-latest-1.amd64.deb
   ```

   Adjust the download link and installation command based on your operating system. Refer to the [NCPA documentation](https://www.nagios.org/ncpa/getting-started.php) for details.

2. Edit the NCPA configuration file (typically located at `/usr/local/ncpa/etc/ncpa.cfg`) to set the `api_token` and configure allowed hosts.

3. Start and enable NCPA service:
   ```bash
   sudo systemctl enable ncpa_listener
   sudo systemctl start ncpa_listener
   ```


### On the Nagios server

1. Download and install the NCPA plugin:
   ```bash
   cd /tmp
   wget https://github.com/NagiosEnterprises/ncpa/archive/v3.1.3

2. Extract the plugin and move it to the plugins directory:
   ```bash
   tar -xzf v3.1.3.tar.gz
   cd ncpa-3.1.3/plugins
   sudo cp check_ncpa.py /usr/local/nagios/libexec/

3. Modify permissions:
   ```bash
   sudo chmod +x /usr/local/nagios/libexec/check_ncpa.py
   ```

4. Define a new command in Nagios to use the NCPA plugin.
   Open the Nagios command configuration file:
   ```bash
   sudo nano /usr/local/nagios/etc/objects/commands.cfg
   ```
   Add the following definition:
   ```bash
   define command {
       command_name    check_ncpa
       command_line    $USER1$/check_ncpa.py -H $HOSTADDRESS$ -t '<API_TOKEN>' -M $ARG1$
   }
   ```
   Replace `<API_TOKEN>` with the actual API token configured in the NCPA agent on the remote server.

5. Create a host definition for the remote server.
   Open the Nagios host configuration file:
   ```bash
   sudo nano /usr/local/nagios/etc/servers/remote_host.cfg
   ```
   Add the following:
   ```bash
   define host {
       use         linux-server
       host_name   remote_host
       alias       Remote Host
       address     <REMOTE_SERVER_IP>
       max_check_attempts 5
       check_period 24x7
       notification_interval 30
       notification_period 24x7
   }
   ```
   Replace `<REMOTE_SERVER_IP>` with the actual IP address of the remote server.

6. Define a service to monitor CPU usage on the remote server using NCPA.
   In the same `remote_host.cfg` file, add:
   ```bash
   define service {
       use                 generic-service
       host_name           remote_host
       service_description CPU Usage
       check_command       check_ncpa!cpu/percent
   }
   ```
   You can add more services like memory usage (`memory/virtual`), disk usage (`disk/logical/|/percent`), etc.

7. Restart Nagios to apply the changes
   ```bash
   sudo systemctl restart nagios
   ```

### Verify the setup
- Go to the Nagios web interface (`http://your.server.ip.address/nagios`)
- Check under Hosts to see if the remote server is listed.
- Check under Services to verify if CPU usage monitoring is working.