Nagios® Version 1.0 Documentation Copyright © 1999-2002 Ethan Galstad Email: [email protected] Last Updated: 08-28-2002 [ Table of Contents ] Nagios and the Nagios logo are registered trademarks of Ethan Galstad. All other trademarks, servicemarks, registered trademarks, and registered servicemarks mentioned herein may be the property of their respective owner(s). The information contained herein is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE WARRANTY OF DESIGN, MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE. Version 1.0 Documentation Table of Contents About What is Nagios? System requirements Licensing Downloading the latest version Other monitoring utilities Release Notes What's new in this version Change log Support Frequently Asked Questions (FAQs) Mailing lists Contract help Getting Started Advice for beginners Installing Nagios Compiling and installing Nagios Setting up the web interface Configuring Nagios Configuration overview Main configuration file options Object configuration file options CGI configuration file options Configuring authorization for the CGIs Extended information configuration Running Nagios Verifying the configuration Starting Nagios Stopping and restarting Nagios Nagios Plugins Standard plugins Writing your own plugins Nagios Addons nrpe- Daemon and plugin for executing plugins on remote hosts nsca- Daemon and client program for sending passive check results across the network Theory Of Operation Determing status and reachability of network hosts Network outages Notifications Plugin theory Service check scheduling State types Time periods Advanced Topics Event handlers External commands Indirect host and service checks Passive service checks Volatile services Service result freshness checks Distributed monitoring Redundant and failover monitoring Detection and handling of state flapping Service check parallelization Notification escalations Monitoring service and host clusters Host and service dependencies State stalking Performance data Scheduled host and service downtime Database support Using the embedded Perl interpreter Object inheritence using template-based config data Time-saving tips for templated-based object definitions Integration With Other Software Portsentry SNMP Traps TCP Wrappers Miscellaneous Securing Nagios Tuning Nagios for maximum performance Using macros in commands Information on the CGIs Custom CGI headers and footers About NagiosTM What Is This? NagiosTM is a system and network monitoring application. It watches hosts and services that you specify, alerting you when things go bad and when they get better. NagiosTM was originally designed to run under Linux, although it should work under most other unices as well. For more information on what operating systems Nagios will and will not run under, see the OS ports page at http://www.nagios.org/ports.shtml. Some of the many features of NagiosTM include: ● Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.) ● Monitoring of host resources (processor load, disk usage, etc.) ● Simple plugin design that allows users to easily develop their own service checks ● Parallelized service checks ● Ability to define network host hierarchy using "parent" hosts, allowing detection of and distinction between hosts that are down and those that are unreachable ● Contact notifications when service or host problems occur and get resolved (via email, pager, or user- defined method) ● Ability to define event handlers to be run during service or host events for proactive problem resolution ● Automatic log file rotation ● Support for implementing redundant monitoring hosts ● Optional web interface for viewing current network status, notification and problem history, log file, etc. System Requirements The only requirement of running Nagios is a machine running Linux (or UNIX variant) and a C compiler. You will probably also want to have TCP/IP configured, as most service checks will be performed over the network. You are not required to use the CGIs included with Nagios. However, if you do decide to use them, you will need to have the following software installed... 1. A web server (preferrably Apache) 2. Thomas Boutell's gd library version 1.6.3 or higher (required by the statusmap and trends CGIs) Licensing NagiosTM is licensed under the terms of the GNU General Public License Version 2 as published by the Free Software Foundation. This gives you legal permission to copy, distribute and/or modify Nagios under certain conditions. Read the 'LICENSE' file in the Nagios distribution or read the online version of the license for more details. NagiosTM is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE WARRANTY OF DESIGN, MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE. Acknowledgements Several people have contributed to Nagios by either reporting bugs, suggesting improvements, writing plugins, etc. A list of some of the many contributors to the development of Nagios can be found at http://www.nagios.org. Downloading The Latest Version You can check for new versions of Nagios at http://www.nagios.org. Other Monitoring Utilities In case you weren't aware, there are other network monitoring utilities available besides Nagios. I think Nagios is a pretty good contender, but I'm obviously biased. Here are links to a few other free monitoring utilities. There are many others that are not listed here - search the net (or Freshmeat) and you'll find them. ● Angel Network Monitor ● Autostatus ● Big Brother ● HiWAyS ● MARS ● Mon ● Netup (French) ● NocMonitor ● NodeWatch ● Penemo ● PIKT ● RITW ● Scotty ● Spong ● Sysmon Nagios and the Nagios logo are trademarks of Ethan Galstad. All other trademarks, servicemarks, registered trademarks, and registered servicemarks may be the property of their respective owner(s). What's New in Version 1.0 Important: Make sure you read through the documentation (especially the FAQs) before sending a question to the mailing lists. Many of the changes described below are the direct result of this project being renamed from NetSaint. Transitioning from NetSaint to Nagios will undoubtedly take some time, but it'll be well worth it. Change Log The change log for Nagios can be found online at http://www.nagios.org or in the Changelog file in the root directory of the source code distribution. Changes 1. User/Group Change. The default user/group that Nagios runs under is now nagios/nagios. 2. Directory Change. The default directory that Nagios gets installed in is now /usr/local/nagios. 3. URL Changes. The base URLs for accessing the HTML files and CGIs through the web interface are now /nagios/ and /nagios/cgi-bin/, respectively. 4. Config File Changes. The main config file is now nagios.cfg and the CGI config file is now cgi.cfg. 5. Process Check Command Changes. The old process_check_command variable in the CGI config file has been renamed to nagios_check_command. Also, if you do not specify a check command, the CGIs will assume the Nagios process is running properly. 6. Archive Changes. Archived log files from Netsaint must be renamed from "netsaint-date.log" format to "nagios-date.log" format if you want to make them available to the Nagios CGIs. You can rename all your archived log files with the following command (assuming you've already moved them to their new directory location): rename netsaint nagios netsaint*.log 7. Retention File Format Change. The format of the retention file (or database, if that's what you were using) has changed to support more variables. No conversion utility is yet available, which means you'll either have to find a way to manually convert your retention data, or lose it when you make the changeover. 8. Database Schema Changes. The database schema for status, retention, comment, and extended information data has changed. If you were using database support previously, you'll either have to recreate the databases using the sample scripts provided in the contrib/database directory just alter your existing tables (an exercise which will be left to you). Also note that the default database name is now nagios. New Features 1. Template-Based Object Config File. This is probably the biggest feature which has been added. Use of the template-based object config file format is optional, but highly recommended. Note that the older config file format is still supported if you really want it. The template-based config file is much easier to read, modify, and expand upon compared to the older format. It also allows you to specify host- and service-specific values for things like flap detection thresholds, flap detection and performance data processing options, etc. If you're interested in trying out the new template-based config file format, check out the convertcfg utility in the contrib/ directory of the distribution - it can be used to quickly convert your old config files to the template-based format. More information on the template-based object config file can be found here. 2. Template-Based Extended Info Config File. This is similar to the template-based object configuration file format mentioned above. You can now store extended host and service information in a template- based config file. More information on doing this can be found here. If you wish, you can still use the older style of defining extended information directives in the CGI configuration file as described here. 3. Host Dependencies. You can now define optional host dependencies which will prevent notifications from being sent out for a host if one or more criteria fail. In the past there have been implicit dependencies between hosts that are related through "parenting", but this now allows you to create explicit dependencies between unrelated hosts. More information on dependencies can be found here. 4. Host Escalations. You can now define optional notification escalations for specific hosts. In the past you were only able to define escalations for entire hostgroups. While this was closely matched to non- escalated notification logic, it didn't provide much flexibility. Note that hostgroup escalations are still supported and can be used in conjunction with host escalations. More information on notification escalations can be found here. 5. Freshness Checking.