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Nagios 4 + Nagiosgraph (latest) installation on Ubuntu 12.04 & 14.04

Published: 11-09-2016 | Author: Remy van Elst | Text only version of this article

Table of Contents

Nagios 4

This is a guide on installing the latest Nagios Core (4.2.1) on Ubuntu 12.04 and14.04. Nagios is an open source computer system monitoring, network monitoringand infrastructure monitoring software application. Nagios offers monitoring andalerting services for servers, switches, applications, and services. It alertsthe users when things go wrong and alerts them a second time when the problemhas been resolved. The version in the Ubuntu 12.04 repositories is quite old, itis still the in the 3 branch. This guide helps to fix that by using the latestNagios version. We also install Nagiosgraph, a plugin for Nagios which gives yougraps of the metrics.

If you like this article, consider sponsoring me by trying out a Digital OceanVPS. With this link you'll get $100 credit for 60 days). (referral link)

You can find more information about Nagios on the official website:

The description of Nagios Core from their website:

Nagios Core is the monitoring and alerting engine that serves as theprimary application around which hundreds of Nagios projects are built. Itserves as the basic event scheduler, event processor, and alert managerfor elements that are monitored. It features several APIs that are used toextend its capabilities to perform additional tasks, is implemented as adaemon written in C for performance reasons, and is designed to run nativeon Linux/*nix systems.


We are going to do the following:

At the end of this tutorial you will have a fully up to date Nagios Coreinstallation, with the latest plugins, the latest NRPE, the webinterface set upwith authentication and ssl, Nagios Graph integrated and MRTG installed tomonitor the health of Nagios.

This was written and tested on Ubuntu 12.04 and 14.04, both 32 and 64 bit.

Whats new in Nagios Core 4?

Major performance increases :

Other nice changes :

No more embedded perl :

See this page for the full listing of new stuff in Nagios 4

Note about currently installed Nagios versions

Make sure you remove all currently installed Nagios versions and packages.Better yet, start on a new empty server/vm.

Note about the plugins and NRPE

We are compiling the latest version of the plugins and NRPE on the NagiosServer. On the Nagios clients, you do not have to do this. The version ofNRPE in the Ubuntu repositories works with this newer Nagios version. The samegoes for the plugins.

Note about packages and checkinstall

We are using checkinstall here to create a debian package of the source wecompile. I do this because it gives more flexibility in managing the softwareafterwards. Upgrading or uninstalling the packages is easier than removing allthe things make install placed. Furthermore, it makes it more clear for otheradministrators which software is installed.

If you for example want to upgrade Nagios when it was installed via thistutorial with checkinstall, repeat the tutorial with only the version numberchanged.

Install required packages

Install the packages required for compilation, apache and mail functionality:

apt-get install apache2 libapache2-mod-php5 build-essential libgd2-xpm-devlibssl-dev sendmail-bin sendmail heirloom-mailx wget apache2-utils curldaemon apt-file libnet-snmp-perl libperl5.14 libpq5 libradius1 libsensors4libsnmp-base libtalloc2 libtdb1 libwbclient0 samba-common samba-common-binsmbclient snmp whois mrtg libmysqlclient15-dev libcgi-pm-perl librrds-perllibgd-gd2-perl

Create the Nagios user

Nagios runs as its own user and has its own groups. We need to create this userand groups. We also make sure the user Apache runs as can access the Nagiosfiles by adding the www-data user to the nagios groups.

groupadd -g 3000 nagiosgroupadd -g 3001 nagcmduseradd -u 3000 -g nagios -G nagcmd -d /usr/local/nagios -c 'Nagios Admin' nagiosadduser www-data nagcmd

Download and Compile Nagios Core

If necessary, create /usr/local/src/nagios4:

mkdir -p /usr/local/src/nagios4

cd into /usr/local/src/nagios4:

cd /usr/local/src/nagios4

(I like to keep my source code and compilation files in one place).

Use wget to download the latest Nagios Core from sourceforge:


Extract it:

tar xf nagios-4.2.1.tar.gzcd nagios-4.2.1

Create a few folders:

mkdir -p /usr/local/nagios/share/{stylesheets,images}

Now start the compilation process. First configure:

./configure --prefix=/usr/local/nagios --with-nagios-user=nagios --with-./nagios-group=nagios --with-command-user=nagios --with-command-./group=nagcmd

Output should look like this:

 General Options: -------------------------        Nagios executable:  nagios        Nagios user/group:  nagios,nagios       Command user/group:  nagios,nagcmd             Event Broker:  yes        Install ${prefix}:  /usr/local/nagios    Install ${includedir}:  /usr/local/nagios/include/nagios                Lock file:  ${prefix}/var/nagios.lock   Check result directory:  ${prefix}/var/spool/checkresults           Init directory:  /etc/init.d  Apache conf.d directory:  /etc/apache2/conf.d             Mail program:  /usr/bin/mail                  Host OS:  linux-gnu Web Interface Options: ------------------------                 HTML URL:  http://localhost/nagios/                  CGI URL:  http://localhost/nagios/cgi-bin/ Traceroute (used by WAP):  /usr/sbin/tracerouteReview the options above for accuracy.  If they look okay,type 'make all' to compile the main program and CGIs.

Then the make process:

make all

Then the use checkinstall, for all the parts:

# This installs the main program, CGIs, and HTML filescheckinstall

In the depends section of the package, make sure to add libc6, perl. Name thepackage nagios4 and give it the correct version, namely 4.2.1. Repeat forall following packages created.

# This installs the init script in /etc/init.dcheckinstall --pkgname=nagios-init make install-init# This installs *SAMPLE* config files in /usr/local/nagios/etccheckinstall --pkgname=nagios-config make install-config#This installs and configures permissions on the directory for holding the external command filecheckinstall --pkgname=nagios-commandmode make install-commandmode# This installs the Apache config file for the Nagios web interfacecheckinstall --pkgname=nagios-webconf make install-webconf

The above command fails on Ubuntu 14.04:

/usr/bin/install -c -m 644 sample-config/httpd.conf /etc/httpd/conf.d/nagios.conf/usr/bin/install: cannot create regular file '/etc/httpd/conf.d/nagios.conf': No such file or directorymake: *** [install-webconf] Error 1

Execute it manually with the correct paths:

/usr/bin/install -c -m 644 sample-config/httpd.conf /etc/apache2/conf-available/nagios.confln -s /etc/apache2/conf-available/nagios.conf /etc/apache2/conf-enabled/nagios.conf

Continue on:

# This installs the Exfoliation theme for the Nagios web interfacecheckinstall --install=no --pkgname=nagios-exfoliation make install-exfoliationdpkg --force-overwrite -i nagios-exfoliation*.deb

If this all goes well, we can continue to the next part.

Download and Compile the Nagios Plugins

Same as above. First create the right folders:

mkdir -p /usr/local/src/nagios-pluginscd /usr/local/src/nagios-plugins

Download the files and untar them:

wget -xf nagios-plugins-2.1.2.tar.gzcd nagios-plugins-2.1.2

Start the compile process:

./configure --with-nagios-user=nagios --with-nagios-group=nagios --with-openssl=/usr/bin/openssl --enable-perl-modules --enable-libtap

Then the make and make install:


Here again, make sure to set libc6, perl as dependencies, name it nagios-plugins and give it the correct version (2.1.2).

This should also go fine. Continue on to NRPE.

Download and Compile NRPE

NRPE allows you to remotely execute Nagios plugins on other Linux/Unix machines. This allows you to monitor remote machine metrics (disk usage, CPU load, etc.). NRPE can also communicate with some of the Windows agent addons, so you can execute scripts and check metrics on remote Windows machines as well.

Same steps as above. First create the right folders:

mkdir -p /usr/local/src/nrpecd /usr/local/src/nrpe

Download the files and extract:

wget -xf nrpe-2.15.tar.gzcd nrpe-2.15

Because of an issue with the openssl library folder we need to use anotherpath than /usr/lib:

./configure --with-ssl=/usr/bin/openssl --with-ssl-lib=/usr/lib/x86_64-linux-gnu

(If you run a 32 bit installation of Ubuntu you can find the right path using(this command: apt-file search libssl | grep libssl-dev. You might need to(install apt-file.)

Now make and make install:

make allcheckinstall

Same thing as above, require libc6, perl in the dependencies, name itcorrectly (nrpe) and give it the right version in checkinstall (2.15).

That part also finished. Continue on.

Setup the upstart script

The current init script which comes with Nagios Core 4.2.1 does not work withUbuntu 12.1.24. See this stackoverflow topic:

The fixes in that topic and on the Nagios forum did not work for me, so I wrotea very simple upstart script.

Place it in /etc/init/nagios.conf:

# nagios - monitoriong system# by https://raymii.orgdescription     "nagios monitoring system"start on virtual-filesystemsstop on runlevel [06]respawnrespawn limit 5 30limit nofile 65550 65550chdir /usr/local/nagios/setuid nagiossetgid nagiosconsole logscript        exec bin/nagios etc/nagios.cfgend script

Don't forget to remove the init script:

mv /etc/init.d/nagios /var/backups/nagios.init

Set up Apache

First we set up a user account for the new nagios user:

htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadminchown nagios:nagcmd /usr/local/nagios/etc/htpasswd.users

Then we create a certificate. This is a self signed one, you can also request acertificate at a provider such as Digicert or Verisign.

mkdir /etc/apache2/sslcd /etc/apache2/ssla2enmod sslopenssl req -x509 -nodes -days 365 -newkey rsa:4096 -out nagios.pem -keyout nagios.key

We also create a folder for nagios under /var/www:

mkdir -p /var/www/nagios4/chown www-data:www-data /var/www/nagios4

Create some symlinks:

ln -s /usr/local/src/nagios4/nagios-4.2.1/contrib/exfoliation/images/favicon.ico /var/www/favicon.ico

Set up a vhost for Nagios. The below file can be used on Ubuntu 12.04. Place itin /etc/apache2/sites-available/nagios.conf:

<VirtualHost *:443>    ServerAdmin    ServerName    DocumentRoot /var/www/nagios    <Directory />        Options FollowSymLinks        AllowOverride None    </Directory>    <Directory /var/www/nagios>        Options -Indexes FollowSymLinks MultiViews        AllowOverride All        Order allow,deny        allow from all    </Directory>     SSLEngine On     SSLCertificateFile /etc/apache2/ssl/nagios.pem     SSLCertificateKeyFile /etc/apache2/ssl/nagios.key</VirtualHost>

On Ubuntu 14.04 the apache version was changed from 2.2 to 2.4 so we need adifferent config file:

<VirtualHost *:443>    ServerAdmin    ServerName    DocumentRoot /var/www/nagios    <Directory />        Options +FollowSymLinks        AllowOverride None    </Directory>    <Directory /var/www/nagios>        Options -Indexes +FollowSymLinks +MultiViews        AllowOverride All        Require all granted    </Directory>     SSLEngine On     SSLCertificateFile /etc/apache2/ssl/nagios.pem     SSLCertificateKeyFile /etc/apache2/ssl/nagios.key</VirtualHost>

Remember to replace with your domain.

On Ubuntu 14.04 we also need to enable the cgi module, otherwise Nagios will saythe process is not running, and viewing cgi files results in downloading them:

a2enmod cgi

Disable the default vhost:

a2dissite default

It might be named 000-default instead of default.

Enable the vhost:

a2ensite nagios # or nagios.conf

Restart apache:

/etc/init.d/apache2 restart

Now we are finished with the installation. Read on for some tweaks I like tomake.


I like to have my config files in /etc/nagios4/conf.d. To do that, we create asymlink first:

ln -s /usr/local/nagios/etc/ /etc/nagios4

Then the conf.d folder:

mkdir /etc/nagios4/conf.d

Then add this to /etc/nagios4/nagios.cfg


I also like to separate my config in directories like so:


/etc/nagios4/conf.d   .   |-contacts   |-hostgroups   |-hosts   |-servicegroups   |-services   |-templates   |-timeperiods

Create it like this:

mkdir -p /etc/nagios4/conf.d/{hosts,services,timeperiods,templates,hostgroups,servicegroups,contacts}

Remember to restart Nagios when you are finished:

service nagios restart

And the nagios is accessible at, with usernamenagiosadmin and your chosen password.

Nagios Graph

Create a folder for the source:

mkdir -p /usr/local/src/nagiosgraph/cd /usr/local/src/nagiosgraph/

Download the latest version:


Extract it:

tar -xf nagiosgraph-1.5.2.tar.gz

Move in to the folder:

cd nagiosgraph-1.5.2

Check that we have all the dependencies installed:

./ --check-prereq

Example output:

checking required PERL modules  Carp...1.29  CGI...3.64  Data::Dumper...2.145  Digest::MD5...2.52  File::Basename...2.84  File::Find...1.23  MIME::Base64...3.13  POSIX...1.32  RRDs...1.4007  Time::HiRes...1.9725checking optional PERL modules  GD...2.46checking nagios installation  found nagios exectuable at /usr/local/nagios/bin/nagioschecking web server installation  found apache executable at /usr/sbin/apache2  found apache init script at /etc/init.d/apache2

Start the installation:

./ --layout standalone --prefix /usr/local/nagiosgraph

Give the default answer to all the questions except the below one:

Modify the Nagios configuration? [n] yPath of Nagios commands file? /usr/local/nagios/etc/objects/commands.cfgModify the Apache configuration? [n] y

If you are on Ubuntu 14.04, change the Apache configuration because the defaultis for Apache 2.2:

Edit the following file:

vim /usr/local/nagiosgraph/etc/nagiosgraph-apache.conf

Change it to:

# enable nagiosgraph CGI scriptsScriptAlias /nagiosgraph/cgi-bin "/usr/local/nagiosgraph/cgi"<Directory "/usr/local/nagiosgraph/cgi">   Options ExecCGI   AllowOverride None   Require all granted</Directory># enable nagiosgraph CSS and JavaScriptAlias /nagiosgraph "/usr/local/nagiosgraph/share"<Directory "/usr/local/nagiosgraph/share">   Options None   AllowOverride None   Require all granted</Directory>

Restart Nagios and Apache:

service nagios restartservice apache2 restart

You can now view the graphs at

We can integrate these graphs into Nagios with a little hack. Nagios supportsnotes_url and action_url. These can be put per host/service in the Nagiosconfig and allow for a link to a internal knowledge base article or a procedurepage or whatever for that host.

We can also place a javascript url to the graphs there. Place this inside aservice check:

action_url      /nagiosgraph/cgi-bin/show.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&geom=1000x200' onMouseOver='showGraphPopup(this)' onMouseOut='hideGraphPopup()' rel='/nagiosgraph/cgi-bin/showgraph.cgi?host=$HOSTNAME$&service=$SERVICEDESC$

For example, the Load of the system:

define service {        use                     local-service        host_name               localhost        service_description     Load        check_command           check_local_load!5.0,4.0,3.0!10.0,6.0,4.0        action_url              /nagiosgraph/cgi-bin/show.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&geom=1000x200' onMouseOver='showGraphPopup(this)' onMouseOut='hideGraphPopup()' rel='/nagiosgraph/cgi-bin/showgraph.cgi?host=$HOSTNAME$&service=$SERVICEDESC$}

For the ping check you can show both RTA and packet loss:

define service {        use                     local-service        host_name               localhost        service_description     PING        check_command           check_ping!100.0,20%!500.0,60%        action_url              /nagiosgraph/cgi-bin/show.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&db=pl,data&db=pl,warn&db=pl,crit&geom=1000x200' onMouseOver='showGraphPopup(this)' onMouseOut='hideGraphPopup()' rel='/nagiosgraph/cgi-bin/showgraph.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&db=pl,data&db=pl,warn&db=pl,crit        notes_url               /nagiosgraph/cgi-bin/show.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&db=rta,data&db=rta,warn&db=rta,crit&geom=1000x200' onMouseOver='showGraphPopup(this)' onMouseOut='hideGraphPopup()' rel='/nagiosgraph/cgi-bin/showgraph.cgi?host=$HOSTNAME$&service=$SERVICEDESC$&db=rta,data&db=rta,warn&db=rta,crit}

We need to include the Nagios Graph Javascript in Nagios to make sure themouseover works. Edit or create the following file:

vim /usr/local/nagios/share/ssi/common-header.ssi

Place the following in there:

script type="text/javascript" src="/nagiosgraph/nagiosgraph.js"></script

Now save and reload Nagios:

service nagios restart

We are going to add a link to here to the menu, but first we'll configure MRTG.


We are going to use MRTG to create some information about how Nagios is running.It shows you stats about how many check run and how long they take. This givesyou insight in your monitoring system.

Copy the included configuration from Nagios:

cp /usr/local/src/nagios4/nagios-4.2.1/sample-config/mrtg.cfg /usr/local/nagios/etc/

Create a folder for the graphs and files:

mkdir -p /usr/local/nagios/share/stats

Configure MRTG to use this folder:

vim /usr/local/nagios/etc/mrtg.cfg

Add the following at the top of the file:

WorkDir: /usr/local/nagios/share/stats

Do the initial run:

env LANG=C /usr/bin/mrtg /usr/local/nagios/etc/mrtg.cfg

Create the HTML pages:

/usr/bin/indexmaker /usr/local/nagios/etc/mrtg.cfg --output=/usr/local/nagios/share/stats/index.html

Finally create a cron job to run MRTG every 5 minutes:

vim /etc/cron.d/mrtg-nagios

Add the following:

*/5 * * * *  root  env LANG=C /usr/bin/mrtg /usr/local/nagios/etc/mrtg.cfg

You can now navigate to to see the graphs.


Last but not least we'll add two links to the Nagios menu to these new tools.

Edit the sidebar file:

vim /usr/local/nagios/share/side.php

And add the following somewhere in the menu:

<div class="navsection">    <div class="navsectiontitle">Extra Tools</div>        <div class="navsectionlinks">            <ul class="navsectionlinks">                <li><a href="/nagios/stats" target="<?php echo $link_target;?>">MRTG stats</a></li>                <li><a href="/nagiosgraph/cgi-bin/show.cgi" target="<?php echo $link_target;?>">Nagios Graph</a></li>            </ul>        </div>    </div></div>

Save and reload Nagios. You can now start to configure the clients and enjoyyour awesome Nagios.

Tags: apache, monitoring, nagios, nagios-core, nrpe, tutorials, ubuntu