Chapter 4: Nagios Basics

Chapter 4 - from the book Nagios: System and Network Monitoring by Wolfgang Barth -- Reprinted by permission from No Starch Press and Open Source Press.  Available at booksellers now.  Full book details are at the bottom of the article.

1 The parameter name parents can be explained by the fact that there are scenarios--such as in high availability environments--in which a host has two upstream routers that guarantee the Internet connection, for example.

Book Summary

Good system administrators know about network or service problems long before anyone asks, â

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Suggestion for the book

Anonymous's picture

You might consider a quickstart guide in the book. Most people who purchase a book like this are interested in getting up and running, even in a minimal configuration, first... not memorizing a plethora of detail beforehand.

While manually going through the book, following step-by-step to configure nagios, the daemon complained because there were missing pieces such as defining 24x7 "somewhere" - that's not clearly explained. details like that which can throw a new reader off very easily.

Quote: Although the

Anonymous's picture

Quote: Although the check_interval parameter provides a way of forcing regular host checks, there is no real reason to do this.

This is not true. Example: Mail Server serving up IMAP on port 143 goes DOWN due to having the power go out. When the machine gets turned back on the IMAP service is not turned on by default (or insert whatever scenario that would make the IMAP service non-functional now, iptables, hosts.deny, etc.). Nagios continues to check for port 143 listening on this server and NOT whether the machine responds or not. This machine will continue to show as DOWN as long as the service is non-responsive.

There are only two fixes that I have found for this. 1: Turn on aggressive_host_checking which will kill any machine with more than 1000 active service checks. 2. Use a host checking mechanism as a service. Preferably a quick one icmp packet check.

nice nagios tutorials

prem's picture

this is very easy installation and configuration for Nagios hope this will help more people installing nagios plugins and examples of how to use plugins

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