Installing nagios on linux

Installing nagios on linux

This guide is intended to provide you with simple instructions on how to install Nagios from source (code) on Ubuntu and have it monitoring your local machine inside of 20 minutes. No advanced installation options are discussed here — just the basics that will work for 95% of users who want to get started.

These instructions were written based on an Ubuntu 14.04 — Server installation. They should work with most recent vesrions of Ubuntu with minor changes on some versions.

What You’ll End Up With

If you follow these instructions, here’s what you’ll end up with:

• Nagios and the plugins will be installed underneath /usr/local/nagios
• Nagios will be configured to monitor a few aspects of your local system (CPU load, disk usage, etc.)
• The Nagios web interface will be accessible at http://localhost/nagios/

Required Packages

Make sure you’ve installed the following packages on your Ubuntu installation before continuing.

• Apache 2
• PHP
• GCC compiler and development libraries
• GD development libraries

You can use apt-get to install these packages by running the following commands:

sudo apt-get install apache2 libapache2-mod-php5 build-essential libgd-dev

1) Create Account Information

Create a new nagios user account and give it a password.

/usr/sbin/useradd -m -s /bin/bash nagios passwd nagios

You will need to also add a nagios group (if it’s not created by default).

/usr/sbin/groupadd nagios /usr/sbin/usermod -G nagios nagios

Create a new nagcmd group for allowing external commands to be submitted through the web interface. Add both the nagios user and the apache user to the group.

/usr/sbin/groupadd nagcmd /usr/sbin/usermod -a -G nagcmd nagios /usr/sbin/usermod -a -G nagcmd www-data

2) Download Nagios and the Plugins

Create a directory for storing the downloads.

mkdir ~/downloads cd ~/downloads

Download the source code tarballs of both Nagios Core and the Nagios plugins (visit https://www.nagios.org/download/ for links to the latest versions). These directions were tested with Nagios 4.2.1 and Nagios Plugins 2.1.3.

wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-4.2.1.tar.gz wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-2.1.3.tar.gz

3) Compile and Install Nagios Core

Extract the Nagios Core source code tarball.

cd ~/downloads tar xzf nagios-4.2.1.tar.gz cd nagios-4.2.1

Run the Nagios configure script, passing the name of the group you created earlier like so:

./configure --with-command-group=nagcmd

Compile the Nagios Core source code.

Install binaries, init script, sample config files and set permissions on the external command directory.

make install make install-init make install-config make install-commandmode

Don’t start Nagios Core yet — there’s still more that needs to be done.

4) Customize Configuration

Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios Core. You’ll need to make just one change before you proceed .

Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor and change the email address associated with the nagiosadmin contact definition to the address you’d like to use for receiving alerts.

vi /usr/local/nagios/etc/objects/contacts.cfg

5) Configure the Web Interface

Install the Nagios Core web config file in the Apache conf.d directory.

Create a nagiosadmin account for logging into the Nagios Core web interface. Remember the password you assign to this account — you’ll need it later.

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

Restart Apache to make the new settings take effect.

Note: Consider implementing the ehanced CGI security measures described here to ensure that your web authentication credentials are not compromised.

6) Compile and Install the Nagios Plugins

Extract the Nagios plugins source code tarball.

cd ~/downloads tar xzf nagios-plugins-2.1.3.tar.gz cd nagios-plugins-2.1.3

Compile and install the plugins.

./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install

7) Start Nagios Core

Configure Nagios Core to automatically start when the system boots.

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

Verify the sample Nagios Core configuration files.

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

If there are no errors, start Nagios Core.

8) Login to the Web Interface

You should now be able to access the Nagios Core web interface at the URL below. You’ll be prompted for the username (nagiosadmin) and password you specified earlier.

Click on the «Service Detail» navbar link to see details of what’s being monitored on your local machine. It will take a few minutes for Nagios Core to check all the services associated with your machine, as the checks are spread out over time.

9) Other Modifications

If you want to receive email notifications for Nagios Core alerts, you need to install the mailx (Postfix) package.

sudo apt-get install mailx sudo apt-get install postfix

You’ll have to edit the Nagios Core email notification commands found in /usr/local/nagios/etc/objects/commands.cfg and change any ‘/bin/mail’ references to ‘/usr/bin/mail’. Once you do that you’ll need to restart Nagios Core to make the configuration changes live.

sudo /etc/init.d/nagios restart

Configuring email notifications is outside the scope of this documentation. Refer to your system documentation, search the web, or look to the Nagios Support Portal or Nagios Community Wiki for specific instructions on configuring your Ubuntu system to send email messages to external addresses.

10) You’re Done

Congratulations! You sucessfully installed Nagios Core. Your journey into monitoring is just beginning. You’ll no doubt want to monitor more than just your local machine, so check out the following docs .

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How to Install Nagios Server on Ubuntu Linux

This brief tutorial shows students and new users how to install and configure the Nagios monitoring server on Ubuntu 16.04 | 17.10 | 18.04 LTS servers.

For those who don’t know about Nagios, it’s software that monitors networks, hardware, servers, and other devices connected to the web. A complete enterprise-grade network, server, and log monitoring system.

This post will show you how to perform a basic configuration after installation. You can also log on to the Nagios server once installed.

For more about Nagios, please visit its homepage.

When you’re ready, continue below with the steps:

Install Apache2

Before installing Nagios server packages, ensure the Apache2 HTTP server is installed. To do that on Ubuntu, run the commands below.

sudo apt update sudo apt install apache2

Install PHP Packages

Nagios server also requires that PHP and related modules be installed. If you don’t have these, it will automatically install them when you run the commands to install Nagios. For example, the commands below install PHP and related packages.

sudo apt install php php-cgi libapache2-mod-php php-common php-pear php-mbstring

Install Nagios Server Packages

To get Nagios on Ubuntu systems, run the commands below. The commands also include an essential plugin to monitor the Nagios server itself.

sudo apt install nagios3 nagios-plugins-basic

When you run the above command, you’ll be prompted to create a password for nagiosadmin account.

┌─────────────────────────────────────────────────┤ Configuring nagios3-cgi ├─────────────────────────────────────────────────┐ │ Please provide the password to be created with the "nagiosadmin" user. │ │ │ │ This is the username and password you will use to log in to your nagios installation after configuration is complete. If │ │ you do not provide a password, you will have to configure access to nagios yourself. │ │ │ │ Nagios web administration password: │ │ │ │ ___________________________________________________________________________________________________________________________ │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

Configure Nagios Server

Once the Nagios server is installed, run the commands below to open its default configuration file.

sudo nano /etc/nagios3/nagios.cfg

Then make the highlighted changes below and save the file.

# EXTERNAL COMMAND OPTION # This option allows you to specify whether or not Nagios should check # for external commands (in the command file defined below). By default # Nagios will *not* check for external commands, just to be on the # cautious side. If you want to be able to use the CGI command interface # you will have to enable this. # Values: 0 = disable commands, 1 = enable commands check_external_commands=1 

Next, run the commands below to open Nagios Apache2 config file.

sudo nano /etc/nagios3/apache2.conf

Then limit access from the localhost and local subnet only.

# nagios 1.x: #Alias /nagios /usr/share/nagios3/htdocs Options FollowSymLinks DirectoryIndex index.php index.html AllowOverride AuthConfig Order Allow,Deny Allow From localhost 10.0.0.0/24  

Save the file and continue below.

Next, run the commands below to adjust the Nagios folder permissions.

sudo chgrp -R www-data /var/lib/nagios3 sudo root@dlp:~# chmod 750 /var/lib/nagios3/rw

After that, restart Nagios2 and Apache2.

sudo systemctl restart nagios3.service sudo systemctl restart apache2.service

Finally, open your browser, browse the server hostname or IP address, and log on to the Nagios server.

With username: nagiosadmin and the password you created above.

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Richard W

I love computers; maybe way too much. What I learned I try to share at geekrewind.com.

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