Chapter 13. Network Monitoring with Nagios

13.0. Introduction

In this chapter, you’ll learn how to install and configure Nagios to monitor network services, host processes, and hardware. Nagios is so flexible it would take a couple of books to detail everything it can do, so we’re going to focus on the most common functions to build a good foundation that will let Nagios grow as your network grows.

In this chapter, you will learn how to:

  • Monitor services like HTTP, SSH, name services, and mail services

  • Monitor system processes and hardware usage

  • Receive alerts when there are problems

Why Nagios, when the FOSS world offers a multitude of good network monitors? You could probably choose one with a coin toss and be happy with it. Nagios’ strength is its modular design, which permits the greatest flexibility and room for growth. The grunt work is done with plug-ins. You may use or modify the official Nagios plug-ins, try some of the many third-party plug-ins, or write your own. Plug-ins make Nagions future-proof; for example, as more devices become SNMP-aware, you may wish to add or write SNMP plug-ins.

One caveat about plug-ins: Nagios is Free Software, licensed under GPL2. Third-party plug-ins are released under all manner of licenses, so you’ll want to be careful and not assume they are also GPL.

Nagios sees your network as hosts or services. Host checks are simple pings. Service checks encompass everything, including the usual services such as HTTP, DNS, SSH, as well as processes such as ...

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