Nagios

Table of Contents

Basic
Advanced
Even more advanced

This is the definitive Quickstart Beginners Guide to Nagios in 24 hours for Dummies.

Why this guide ?

Everybody knows Nagios is the definitive open source network monitoring solution. It can be used from simply checking to see if a network host is still up, all the way up to monitoring specific services on remote hosts, and even to trigger corrective action if a problem is detected. And tell you about all that by mail, phone, fax, pager, sirenes and flashing lights, and possibly also by carrier pigeon.

Setting up Nagios isn't really all that hard. What's hard is

  1. Deciding what to monitor, and how, then
  2. Configuring Nagios to do ecaxtly that
  3. Keeping your configuration files managable, and
  4. Organizing your configuration in such a way that you don't have to start from scratch for every new host or service you want to add.

When you search the web, you'll find lots of reference manuals and howtos for Nagios - detailing every available option, keyword and parameter Nagios knows about. What the usually don't tell you is how you compile all that together into a working system. In that respect, Nagios is a typical open source framework : it can do anything (within the realm of its goals), but it expects you to tell it what to do - it hardly does anything 'by default'.

What this guide will do for you

One of the risks you run is that you get busy with Nagios and figure out how to make it do a few simple checks, then add some more, and some more, and something a little more complex, and before you know it your swamped in a configuration where you don't know what's where and why, even if you put it there yourself. Adding to or modifying your Nagios config then becomes a mjor pain in the you know where.

What we'll do in stead is indeed start small and simple, but in an organized way, so we can effortessly scale up to more, bigger, more complex, ... without loosing oversight and managability. This means we put in a little extra work in the beginning, and reap the benefits as we expand.

In the end, you'll have a rather simple yet elaborate nagios configuration, enough insight in how Nagios works and what sort of thing Nagios can do to further tweak it to your needs, and a solid base for scaling up if you'd need or want to.

Alternative

This is a write-up about how I set up Nagios in the organization where I work. It monitors routers and switches, our Windows and Linux servers (10-15 hosts) and some of the services and daemons they run, over a number of different networks. It also monitors hardware (such as disk SMART status, RAID status, ...) and system health (load, ...), and monitors the availability of a couple of external servers that provide web applications and web services we need.

I imagine such a setup would be quite sufficient for a small or medium sized business or organization, and that it already has most of what you need to make it scale to larger environments.

Alternatively, you could also get professional support and consultancy from Nagios Enterprises http://www.nagios.com/contact/.


Koen Noens
Februari 2012

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The Definitive Quickstart Beginners Guide to Nagios in 24 hours for Dummies by Koen Noens is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.