How to use Raspberry Pi to monitor network? (Nagios)


Today I wanted to use my Raspberry Pi to monitor my network with Nagios.
But I was lost trying to find out what was the best option to do this.
I saw many how-to guides about NEMS, Nagios3 but nothing perfect with the latest Nagios version.
I’ll explain here what I found and how to do the same step by step.

How to install Nagios on the Raspberry Pi?

  • Install the prerequisites: Raspberry Pi OS, Apache, PHP.
  • Download Nagios Core and Plugins source code from the official website.
  • Install and configure them with Apache.
  • Add your hosts, services and command in the Nagios configuration files.

Yes, Nagios from source is the best way to monitor your network on Raspberry Pi.
Nagios is like a failure detector, it will check one thing regularly (like every 5 minutes) and alert you when this check doesn’t work as expected.

In this post I’ll explain how to install Nagios on your Raspberry Pi to check your network status.
But I’ll start by listing all the ways to get Nagios I found on Internet and to show you why most of them are useless or unsuitable.

What is the best way to get Nagios on Pi?

I’ll start this post by explaining to you what I found to get Nagios quickly on the Raspberry Pi, and why they are bad options for you.

NagiosPi?

My first search showed me “NagiosPi”.
I was excited to see that Nagios created a specific version for the Raspberry Pi.
This is the main reason that led me to install it on my Pi.
But I was quickly cooled, seeing this is a side project, with no update since 2013.

This was not suitable for me, I know that Nagios releases new updates at least once a year, so I want something recent.

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APT?

Next step, I looked into apt repository what I could get.
Did the guy from NagiosPi stopped his project because Raspbian added the Nagios package in apt?
Maybe, but I only find Nagios 3 in the apt sources, the latest version when I wrote this line was Nagios 4.4.6.

It could be the easiest way to get Nagios, but I want the latest version or not too far from it.

NEMS?

Next search, I found a pre-configured SD card with Nagios and a lot of monitoring tools.
This is the NEMS Linux project, NEMS stands for Nagios Enterprise Monitoring Server.
Seems interesting no?

Yes, I tried it, but this was not suitable for Raspberry Pi.
Even when doing nothing, I have a lot of load, and couldn’t do anything without lag.
Maybe too many tools for the Raspberry Pi.

load average on nems

From sources?

The last option I was thinking about was to install Nagios manually from the sources.
But I thought this will be difficult and time-consuming to compile everything.

Hum … not so long finally, maybe 30min to get everything working with the latest version.
So for me, it’s really the best option I found, and I’ll now explain to you how to install it on your Raspberry Pi.

How to install Nagios on your Raspberry Pi?

Install Raspbian

First thing you need, is an operating system 🙂
Start with Raspbian, I think Raspbian Lite is perfect for this goal, but take the Desktop version if you prefer.

Here are the first steps you need to complete before going further:

That’s it, we are ready to start.

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Downloads and prerequisites

Nagios is a web interface, so we need to install Apache and PHP:
sudo apt install apache2 libapache2-mod-php

Then there are two things we need to download and install:

  • Nagios Core: It’s the main part of the Nagios system.
  • Nagios Plugins:  This will add basic check commands to Nagios, so you’ll not have to create all the scripts yourself.

We need to download sources for them, check their websites for the latest version:
Nagios Core downloads
Nagios Plugins downloads

Finally, download archives with wget:
mkdir /home/pi/Downloads
cd /home/pi/Downloads
wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.6.tar.gz
wget http://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz

Now we are ready to move to the installation process.

Install Nagios

Create Nagios user and group

We need to create a specific user for Nagios, and a group for Nagios and Apache users (nagcmd):
sudo useradd -m -s /bin/bash nagios
sudo groupadd nagcmd
sudo usermod -a -G nagcmd nagios
sudo usermod -a -G nagcmd www-data

Compile and install nagios

Now we have to extract files from the archive, compile the sources and install Nagios on the Raspberry Pi:

  • Move to the “Downloads” directory:
    cd /home/pi/Downloads
  • Extract files from the archive downloaded before:
    tar zxvf nagios-4.4.6.tar.gz
  • Don’t forget to change the version number if you download another one.
  • Compile :
    cd nagios-4.4.6/
    ./configure – with-command-group=nagcmd
    make all

    This could take a few minutes.
  • Install:
    sudo make install
    sudo make install-init
    sudo make install-config
    sudo make install-commandmode

This is the end of the Nagios core installation.
We now need to configure the Apache part to allow access to the Nagios page.

Apache configuration for Nagios

  • Enable the CGI module for Apache:
    sudo a2enmod cgi
  • Copy the Apache configuration to the Apache folder:
    sudo cp sample-config/httpd.conf /etc/apache2/sites-enabled/nagios.conf
  • Create the first user for the web interface:
    sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
  • Restart Apache:
    sudo service apache2 restart
  • Check if you have access to Nagios:
    Go to http://<RASPBERRY IP>/nagios
    (check this tutorial if you don’t know how to find the current IP address).
    You should get something like this:

    It’s normal, we’ll fix that now.

The Nagios installation is almost done, we just need to run the Nagios service.

Start the Nagios service

Nagios has a service running in background to launch a check at a predefined frequency (every 5min for example).
We need to start it to finish the installation:
sudo service nagios start

And to start Nagios automatically on boot:
sudo ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios

If you refresh the web interface, you should now see “Daemon running with PID XXX”.
Everything is fine with Nagios, we just want to add plugins now.

Install Nagios Plugins

Follow this procedure to install the Nagios plugins:

  • Get back to the Downloads folder:
    cd /home/pi/Downloads
  • Extract files from the archive:
    tar zxvf nagios-plugins-2.3.3.tar.gz
  • Compile and install:
    cd nagios-plugins-2.3.3/
    ./configure – with-nagios-user=nagios – with-nagios-group=nagios
    make
    sudo make install

All plugins are now available in the /usr/local/nagios/libexec/ folder and ready to use in Nagios.

You may need to restart Nagios to apply changes:
sudo service nagios restart

How to configure Nagios to fit your needs?

Nagios vocabulary

Nagios uses a specific vocabulary to define each object in the configuration
So first, I have to be sure you know it:

  • Command: a command is basically a script from the Nagios plugins folder, we define it in Nagios to use it later with parameters (ex: check_load is a command).
  • Service: a service is a check that applies to one or more computers, and that uses a command to run a particular verification (ex: check if the load is above 10 on Raspberry Pi is a service).
  • Host: a host is a computer, a server, anything with an IP address.
  • Hostgroup: you can define a host group, like “Raspberry Pi”, and apply the same services to all the hosts inside this group.

We’ll now see how to configure each one in the Nagios configuration file.
For the example I’ll monitor my Raspberry Pi Zero from the Raspberry Pi where Nagios is installed.

Prepare the host

Nagios uses mainly SNMP to connect to other hosts and get all the information.
So we need to install SNMP on every new host before adding it in the configuration file.

This is not mandatory, it depends on which services you’ll create for this host.
Anyway, I’ll show you how to do it, so you have a complete tutorial.

In my case, I followed these steps on the Raspberry Pi Zero:

  • Connect to the host via SSH.
  • Install snmpd:
    sudo apt install snmpd
  • Move to the configuration folder:
    cd /etc/snmp
  • Remove (or backup) the snmpd.conf file:
    sudo rm snmpd.conf
  • Create a new snmpd.conf file:
    sudo nano snmpd.conf
  • Paste these lines into:
    com2sec readonly default RASPBERRYTIPS
    group MyROGroup v1 readonly
    group MyROGroup v2c readonly
    view all included .1 80
    access MyROGroup "" any noauth exact all none none
    sysName Pi Zero

    Replace RASPBERRYTIPS by the community you want to use.
    Replace sysName by your host name or description.
    There are many options available in snmpd.conf, but for this test we don’t need more than that.
  • Save and exit (CTRL+O, CTRL+X)

  • Restart snmpd


    sudo service snmpd restart

We can now add this host in Nagios.

Add a host

  • Go back to the Raspberry Pi hosting Nagios.
  • Move to the objects configuration folder of Nagios:
    cd /usr/local/nagios/etc/objects
  • Create a new file for your host, like pizero.cfg:
    sudo nano pizero.cfg
  • Paste these lines into:
    define host {
    use linux-server  ; Host group to use
    host_name Pi Zero  ; Name of this host
    alias pizero  ; Alias
    address 192.168.1.18  ; IP Address
    }

    This is really a basic host definition, with the host name, alias and IP address.
    We also add it to the Linux servers host group to inherit group-defined services if you add some later

  • Save and exit (CTRL+O, CTRL+X).
  • Now we need to tell Nagios that we added a new file.
    Add this line in /usr/local/nagios/etc/nagios.cfg (just under localhost.cfg will be perfect) .
    cfg_file=/usr/local/nagios/etc/objects/pizero.cfg
  • Restart Nagios:
    sudo service nagios restart
  • Go back to the Nagios web interface, in the Hosts menu.
    You should have a new line like this:
    nagios add host

Nagios already monitors the ping response for our new host, but we want more.
So we need to add a service inside, but first we need to define the command to use.

Add a command

Previously in this tutorial you downloaded and installed Nagios plugins
Nagios plugins provide many commands to check the local host, but not so much for remote hosts.
You can also download many other commands on this website (specifically look for SNMP plugins).

For this example, I’ll monitor the time synchronization between my two Raspberry Pi.

To add a command in Nagios, follow these steps:

  • Move to the plugins folders:
    cd /usr/local/nagios/libexec
  • Run the command without parameters:
    ./check_ntp
  • Note the help message, and parameters you need to pass.
    In my case, I got this error message:
    Usage: check_ntp -H <host> [-w <warn>] [-c <crit>] [-j <warn>] [-k <crit>] [-4|-6] [-v verbose]

    So, I know I have to specify the host IP in the -H argument.
    And maybe a warning and critical threshold with -w and -c
    Other options don’t seem relevant for me

  • Open the commands configuration file:
    sudo nano /usr/local/nagios/etc/objects/commands.cfg
  • Check if your command is already inside and if not, you have to add it like this:
    define command {
    command_name check_ntp
    command_line $USER1$/check_ntp -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$
    }
  • Save, exit and restart Nagios:
    sudo service nagios restart
  • Check that your command is now available in Nagios.
    • Go to the web interface.
    • Click on “Configuration” in the left menu.
    • Choose “Commands” is the list and click “Continue”.
    • You should now see “check-ntp” in the list (or any command you add) .

The command is now ready to be used for your host, but we need to create a new service to apply it.

Add a service

To create a new service, follow these steps:

  • Open your host configuration file:
    sudo nano /usr/local/nagios/etc/objects/pizero.cfg
    Adapt the filename to what you have created before
  • Paste these lines:
    define service {
    use local-service  ; Name of service template to use
    host_name Pi Zero
    service_description Time synchronization
    check_command check-ntp!1!5
    }

    Don’t forget to adapt these lines to your previous configuration.
    On the check_command line, we define all arguments, separated by exclamation points

  • Save and exit.
  • Check your configuration:
    sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
    This could be useful to know if you have configuration errors before restarting Nagios.
    In my case, I wrote check_ntp instead of check-ntp 🙂
  • Restart Nagios:
    sudo service nagios restart

Now in the status detail from your host you should see the new service.

nagios service detail

If you understood how to create a host, a command and a service, you are now ready to do anything in Nagios.
Feel free to download new plugins on Internet, or even code your plugins (it’s nothing more than a basic script to check something).

Video

Network monitor with Nagios on Raspberry Pi

Related questions

Is it possible to create the configuration from the web interface?  Unfortunately no, Nagios doesn’t provide a configuration tool in the Core version. But there are several configuration tools you could install. The one I often use is Thruk, I didn’t try it yet on Raspberry Pi, but you can download it here if you want.

Is it possible to monitor Windows or other hosts? Yes. You could monitor anything on the network. SNMP is also available for Windows and most of the network equipments (router, switch, home automation device, …).  As you can create your check commands, everything is possible.

Conclusion

That’s it, you know how to install and configure a Nagios server on your Raspberry Pi to monitor your network or anything you want.
With this tutorial, you get the latest Nagios version, with no excessive load average (currently 0.00 on my Pi ^^).

Once Nagios is installed, it’s not really different from any Nagios server on Linux.
So feel free to check Linux tutorials for advanced configuration.


Patrick Fromaget

I'm the lead author and owner of RaspberryTips.com. My goal is to help you with your Raspberry Pi problems using detailed guides and tutorials. In real life, I'm a Linux system administrator with a web developer experience.

43 thoughts on “How to use Raspberry Pi to monitor network? (Nagios)

  1. Getting the following error while opening http:///nagios

    Nagios Core

    <frame src="” name=”main” frameborder=”0″ style=””>


    Nagios Core

    www.nagios.org
    Copyright © 2010- Nagios Core Development Team and Community Contributors.
    Copyright © 1999-2010 Ethan Galstad

    Note: These pages require a browser which supports frames

  2. Hi dabance,

    This message doesn’t help
    Can you paste the exact error message? Or a screenshot maybe?

    Thanks

  3. Thank you for the excellent guide.
    Sadly, I’m having trouble installing the nagios plugins because a whole bunch of pre-requisites are missing.
    From the nagios install webpage, there are a bunch of yum packages (which the raspberry pi doesn’t have):

    https://support.nagios.com/kb/article/nagios-core-installing-nagios-core-from-source-96.html#Debian

    eg.
    yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils
    yum install -y perl-Net-SNMP

    Looks like I need to find some equivalents for apt-get…

  4. Hi,

    When attempting to do the following step:

    sudo cp sample-config/httpd.conf /etc/apache2/sites-enabled/nagios.conf

    I get the following error:

    cp: cannot stat ‘sample-config/httpd.conf’: No such file or directory

    Which step creates this file? Or should it have been on my system already? I am on a Raspberry Pi 3 B+

    1. Hi Tommie,

      I don’t know exactly, I think it should be in the Nagios package or archive
      But not a big deal, if it’s not working directly without configuration, you can use this one as an example : https://github.com/ageric/nagios/blob/master/sample-config/httpd.conf.in

  5. Hello Thank you for the guide,
    I am having trouble runnning Nagios.

    I don’t have installed plug-in because before that, when I am accessing to my Nagios web page.
    It says : Nagios Core Not running,
    I check the status of nagios service and nothing special appears :

    ● nagios4.service – LSB: nagios host/service/network monitoring and management system
    Loaded: loaded (/etc/init.d/nagios4; generated)
    Active: active (running) since Mon 2019-07-29 19:15:26 CEST; 13min ago
    Docs: man:systemd-sysv-generator(8)
    Process: 2388 ExecStart=/etc/init.d/nagios4 start (code=exited, status=0/SUCCESS)
    Tasks: 8 (limit: 2200)
    Memory: 3.1M
    CGroup: /system.slice/nagios4.service
    ├─2418 /usr/sbin/nagios4 -d /etc/nagios4/nagios.cfg
    ├─2419 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    ├─2420 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    ├─2421 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    ├─2422 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    ├─2423 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    ├─2424 /usr/sbin/nagios4 –worker /var/lib/nagios4/rw/nagios.qh
    └─2428 /usr/sbin/nagios4 -d /etc/nagios4/nagios.cfg

    Thanks for the help

    1. Hello,

      Do you have an error when you start the service?

      Or can you check the log file?
      I think it’s in /var/log/syslog

  6. Hello,

    Thanks for the fast reply,
    I have find this in the log file regarding Nagios :
    Jul 29 21:19:09 raspberrypi nagios4[4410]: Starting nagios4 monitoring daemon: nagios4.
    Jul 29 21:19:09 raspberrypi nagios4: Nagios 4.3.4 starting… (PID=4440)
    Jul 29 21:19:09 raspberrypi nagios4: Local time is Mon Jul 29 21:19:09 CEST 2019
    Jul 29 21:19:09 raspberrypi nagios4: LOG VERSION: 2.0
    Jul 29 21:19:09 raspberrypi nagios4: qh: Socket ‘/var/lib/nagios4/rw/nagios.qh’ successfully initialized
    Jul 29 21:19:09 raspberrypi nagios4: qh: core query handler registered
    Jul 29 21:19:09 raspberrypi nagios4: nerd: Channel hostchecks registered successfully
    Jul 29 21:19:09 raspberrypi nagios4: nerd: Channel servicechecks registered successfully
    Jul 29 21:19:09 raspberrypi nagios4: nerd: Channel opathchecks registered successfully
    Jul 29 21:19:09 raspberrypi nagios4: nerd: Fully initialized and ready to rock!
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Successfully registered manager as @wproc with query handler
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4442;pid=4442
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4443;pid=4443
    Jul 29 21:19:09 raspberrypi systemd[1]: Started LSB: nagios host/service/network monitoring and management system.
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4446;pid=4446
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4441;pid=4441
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4444;pid=4444
    Jul 29 21:19:09 raspberrypi nagios4: wproc: Registry request: name=Core Worker 4445;pid=4445
    Jul 29 21:19:09 raspberrypi nagios4: Successfully launched command file worker with pid 4450

    I also tried this :
    sudo nagios4 restart
    output :
    Nagios Core 4.3.4
    Copyright (c) 2009-present Nagios Core Development Team and Community Contributors
    Copyright (c) 1999-2009 Ethan Galstad
    Last Modified: 2017-08-24
    License: GPL

    Website: https://www.nagios.org
    Error: Cannot open main configuration file ‘/usr/local/nagios/etc/objects/restart

    But I think that’s normal, there is no “restart” file in this folder

    1. Hi,

      There is no error in your log file, so I don’t know what the problem could be

      Good commands to manage the nagios service are:

      • sudo service nagios start
      • sudo service nagios stop
      • sudo service nagios restart

      You can also try sudo journalctl -xe to see the last errors

  7. The step to make the Nagios service start automatically did not work for me.

    sudo ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios

    It creates the link, but nagios does not start on boot.

    This nagios support article worked for me:
    https://support.nagios.com/forum/viewtopic.php?f=7&t=34604

  8. Hello, I followed you tutorial and it is really good. Had some problems but figured it out. Can you help me with installing Nagios network analyzer on raspbian? Nagios server is already up and working. Can I manually put NAA or not?

    1. Hi Zvonimir,

      Thanks for your feedback

      I’m sorry I didn’t test it, I don’t know if it can work on Raspbian
      But you can try the official documentation here : https://assets.nagios.com/downloads/nagios-network-analyzer/docs/Network_Analyzer_Manual_Installation_Instructions.pdf

      Let us know if you have an answer 🙂
      Good luck

      1. Hello again, NNA is not working on Raspbian.. Tried few different releases and none work. It is not officially supported. Really don’t know how to get this done. Maybe any other way to get nagios analyze some network data? Wrote alot of stuff about Nagios and this project and don’t want to abandon it but thinking about shifting to wireshark

  9. This was an incredible walkthrough! I did have one issue which I figured out. I was attempting to install Nagios Core 4.4.5 and “sudo ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios” didn’t work for me because there was nothing in init.d at all! I googled it a bit and figured out that I needed to instead run “sudo systemctl enable nagios.service” and now my device successfully loads the nagios service at startup. Thanks so much.

  10. Hi, I got to the section to add a host to monitor and both the localhost and my host that I was adding are showing as down.

    I get this error status when I dig a little further:
    (No output on stdout) stderr: execvp(/usr/local/nagios/libexec/check_ping, …) failed. errno is 2: No such file or directory

    Any ideas?

    1. Hello,

      Make sure that the script you try to use exist in this folder (check_ping in libexec)
      But I think it’s one of the default scripts

  11. Used an old Pi2 that I had set up as a LAMP server using Ubuntu 18.04. I had to add sudo make install-daemoninit during install to get the service to start at bootup. Other than that, instructions worked great. Thank you Patrick!

  12. Hi, I am having an issue with adding the host. Everything is fine until I type “sudo service nagios restart” as it throws up the following error:

    “Job for nagios.service failed because the control process exited with error code.
    See “systemctl status nagios.service” and “journalctl -xe” for details.”

    Once I’ve typed “systemctl status nagios.service”

    It shows the following:

    ● nagios.service – Nagios Core 4.4.5
    Loaded: loaded (/lib/systemd/system/nagios.service; enabled; vendor preset: enabled)
    Active: failed (Result: exit-code) since Tue 2020-03-31 16:40:19 BST; 55s ago
    Docs: https://www.nagios.org/documentation
    Process: 26901 ExecStartPre=/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg (code=exited, status=1/FAILURE)
    Process: 26902 ExecStopPost=/bin/rm -f /usr/local/nagios/var/rw/nagios.cmd (code=exited, status=0/SUCCESS)

    Mar 31 16:40:19 raspberrypi nagios[26901]: ***> One or more problems was encountered while processing the config files…
    Mar 31 16:40:19 raspberrypi nagios[26901]: Check your configuration file(s) to ensure that they contain valid
    Mar 31 16:40:19 raspberrypi nagios[26901]: directives and data definitions. If you are upgrading from a previous
    Mar 31 16:40:19 raspberrypi nagios[26901]: version of Nagios, you should be aware that some variables/definitions
    Mar 31 16:40:19 raspberrypi nagios[26901]: may have been removed or modified in this version. Make sure to read
    Mar 31 16:40:19 raspberrypi nagios[26901]: the HTML documentation regarding the config files, as well as the
    Mar 31 16:40:19 raspberrypi nagios[26901]: ‘Whats New’ section to find out what has changed.
    Mar 31 16:40:19 raspberrypi systemd[1]: nagios.service: Control process exited, code=exited, status=1/FAILURE
    Mar 31 16:40:19 raspberrypi systemd[1]: nagios.service: Failed with result ‘exit-code’.
    Mar 31 16:40:19 raspberrypi systemd[1]: Failed to start Nagios Core 4.4.5.

    1. Hi Philip,

      Yes, it’s common as soon as there is a little issue with your configuration

      You can get more details with:
      sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

  13. For anyone doing this in 2020, the latest version as of Aug 2019 is 4.4.5

    https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.5.tar.gz
    https://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz

    Change Log: https://www.nagios.org/projects/nagios-core/history/4x/

  14. Hi, this all worked great until i tried to add a host. No errors at all came up, but still only the local host showing
    Could it be because the Pi Zero is connected wireless through mesh access point and the Pi 3 running Nagios is wired?
    I’ve tries restarting both services but still not being registered
    Thanks

    1. I’m having the same issue. I followed the walkthrough and added hosts but I only get localhost. Not sure what I’m doing wrong.

      1. I’ve actually resolved this issue. The problem was that I had renamed the template/group named from linux_server to something else and Nagios was getting confused. Not sure how to add new group named…

        I am having a different issue however – when I reboot by Pi, Nagios will not startup automatically.

  15. New to Linux. During the Apache Configuration I get “htpasswd: cannot create file /usr/local/nagios/etc/htpasswd.users” at the command:

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

    I don’t think I’ve missed anything?

  16. Hi I have a problem in the configuration of the apache in this step
    sudo cp sample-config/httpd.conf /etc/apache2/sites-enabled/nagios.conf
    after that it appears:
    cp: cannot start ‘sample-config/httpd.conf’ :no such file or directory

    1. HI,

      Do you have this error on starting Apache? or when you try to copy the file?
      Are your sure to be in the correct folder? (does the file exists?)

      1. Using this tutorial (with a few modifications) I’ve successfully installed Nagios 4.4.6 on PiZero with DietPi (since I don’t have the “w” version I’ve used a USB network card for LAN) connection.
        Install and configure DietPi – DietPi instruction on official website
        Connect to Pi using SSH (root user will be used during install so there is no need for “sudo” if connecting with other user you must add sudo or use “sudo su”) :
        [code]
        apt update && apt upgrade
        apt install apache2 libapache2-mod-php gettext build-essential
        mkdir DW_Nagios && cd DW_Nagios
        wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.6.tar.gz && wget https://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz
        useradd -m -s /bin/bash nagios && groupadd nagcmd && sudo usermod -a -G nagcmd nagios && sudo usermod -a -G nagcmd www-data
        tar zxvf nagios-4.4.6.tar.gz
        cd nagios-4.4.6/
        ./configure –with-command-group=nagcmd
        make all
        make install
        make install-init
        make install-config
        make install-commandmode
        a2enmod cgi
        cp sample-config/httpd.conf /etc/apache2/sites-enabled/nagios.conf
        htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
        service apache2 restart
        service nagios start
        ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios
        cd ..
        tar zxvf nagios-plugins-2.3.3.tar.gz
        cd nagios-plugins-2.3.3
        ./configure –with-nagios-user=nagios –with-nagios-group=nagios
        make
        make install
        [/code]

        After that had some issue with nagios service, the following resolve it:
        [code]
        Create this nagios.service file

        # vi /etc/systemd/system/nagios.service
        [Unit]
        Description=Nagios
        BindTo=network.target

        [Install]
        WantedBy=multi-user.target

        [Service]
        User=nagios
        Group=nagios
        Type=simple
        ExecStart=/usr/local/nagios/bin/nagios /usr/local/nagios/etc/nagios.cfg
        # systemctl enable /etc/systemd/system/nagios.service
        # systemctl start nagios
        # systemctl status nagios
        After that you need to restart the Nagios Service.

        # /etc/init.d/nagios restart
        That’s it you should now be able to access Nagios WEBUI.
        [/code]

        Everything worked without issues (usually i had to search for some dependency that was missing from DietPi due to it being such a slimmed down OS).
        Thanks for the article and all the useful comments.
        P.S. Although I had issues posting this comment, getting message : ERROR: Sorry, human verification failed. but no chaptcha was displayed

      2. Wow, dunno what happened to the formatting of my previous message.
        Anyway, if someone is using DietPy and wonder why mail notifications are not working is because you need to install some packages :
        – apt install mailutils sendmail

        After installing them you can run a simple test from terminal using :
        mail -s “This is the subject” email@domain.com <<< 'This is the message'

        Now i still had a small issue since the binary were installed in /usr/bin and nagios was looking for them in /bin, there are two solutions :
        – modify the commands in commands.cfg file
        – make a sim-link using : ln -s /usr/bin/mail /bin/

  17. Hi, when attempting to Check if I have access to Nagios using http:///nagios), it says “No such file or directory”. Do I need to run this on a web browser using the rapsberry pi or in the command line terminal?

  18. Hello Patrick,

    This is a great tutorial did you do a youtube video for this yet? If not you should, this is a great tutorial for nagios on a Raspberry Pi. I believe you covered everythign except how to configure notifications. I have been trying to find an excellent tutorial for that and I cannot. Do you have any experience with notifications? If so please share with us. I actually have nagios working in a Docker Container and it works great just trying to figure out 2 things before I release the tutorial on my website. Thank you so much for your hard work I do appreciate it so much.

    1. Hi Michael,

      Yes, there is a YouTube video (one of my first so not the best one, but it should work).
      I’ve added it in this article.

      For the notifications, I’m just using the default email notifications, and I also have some of them configured with Pushbullet (to get them on my phone).
      It should work easily once the system email configured.

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