Nagios is my favorite open source server and network monitoring application software. It watches hosts and services that you specify, alerting you when things go bad and again when they get better.
If you're planning on installing Nagios, check out this installation guide from Rainer Brunold that gives you step-by-step instructions on how to set it up:
Nagios is a popular host and service monitoring tool used by many administrators to keep an eye on their systems.
Since I wrote a basic installation guide in Jan 2006 on Cool Solutions many new versions were published and many Nagios plugins are now available. Because of that I think it's time to write a series of articles here that show you some very interesting solutions. I hope that you find them helpful and that you can use them in your environment. If you are not yet and nagios user I hope that I can inspire you and you give it a try.
I don't want to write here a full documentation about Nagios, I prefer to give you a basic installation guide so you can set it up very easy and play with it yourself. The installation guide will show you how to install Nagios as well as some interesting extensions and how they integrate into each other. During this installation you will make many modifications to the installation that will help to understand how it works, how you can integrate systems and different services. I will also provide some articles about monitoring special services where I describe what they do and what configuration changes are needed. All together should give you a very good overview and documentation on how you can enhance the Nagios installation yourself.