Nagios Core Documentation

10.11.12.13.More information about these new options can be found here.Adaptive Monitoring:The check timeperiod for hosts and services can now be modified on-the-fly with theappropriate external command (CHANGE HOST CHECK TIMEPERIOD orCHANGE SVC CHECK TIMEPERIOD). Look here for available adaptive monitoringcommands.Notifications:A first notification delay option has been added to host and service definitions to (what else)introduce a delay between when a host/service problem first occurs and when the firstproblem notification goes out. In previous versions you had to use some mighty config-fu withescalations to accomplish this. Now this feature is available to normal mortals.Notifications are now sent out for hosts/services that are flapping when flap detection isdisabled on a host- or service-specific basis or on a program-wide basis. The NOTIFICATIONTYPE macro will be set to "FLAPPINGDISABLED" in this situation.Notifications can now be sent out when scheduled downtime start, ends, and is cancelled forhosts and services. The NOTIFICATIONTYPE macro will be set to "DOWNTIMESTART","DOWNTIMEEND", or "DOWNTIMECANCELLED", respectively. In order to receivenotifications on scheduled downtime events, specify "s" or "downtime" in your contact, host,and/or service notification options.More information on notifications can be found here.Object Definitions:Service dependencies can now be created to easily define "same host" dependencies fordifferent services on one or more hosts. (Read more)Extended host and service definitions (hostextinfo and serviceextinfo, respectively) have beendeprecated. All values that from extended definitions have been merged with host or servicedefinitions, as appropriate. Nagios 3 will continue to read and process older extendedinformation definitions, but will log a warning. Future versions of Nagios (4.x and later) willnot support separate extended info definitions.New hostgroup members, servicegroup members, and contactgroup members directives have beenadded to hostgroup, servicegroup, and contactgroups definitions, respectively. This allows youto include hosts, services, or contacts from sub-groups in your group definitions.New notes, notes url, and action url have been added to hostgroup and servicegroup definition.Contact definitions have the new host notifications enabled, service notifications enabled, andcan submit commands directives to better control notifications and determine whether or notthey can submit commands through the web interface.Host and service dependencies now support an optional dependency period directive. Thisallows you to limit the times during which dependencies are valid.The parallelize directive in service definitions is now deprecated and no longer used. All servicechecks are run in parallel in Nagios 3.There are no longer any inherent limitations on the length of host names or servicedescriptions.Extended regular expressions are now used if you enable the use regexp matching configoption. Regular expression matching is only used in certain object definition directives thatcontain *, ?, , or \.A new initial state directive has been added to host and service definitions, so you can tellNagios that a host/service should default to a specific state when Nagios starts, rather than UPor OK (which is still the default).Object Inheritance:You can now inherit object variables/values from multiple templates by specifying more thanone template name in the use directive of object definitions. This can allow for some verypowerful (and complex) inheritance setups. (Read more)Services now inherit contact groups, notification interval, and notification period from their8

14.15.16.17.associated host if not otherwise specified. (Read more)Host and service escalations now inherit contact groups, notification interval, and escalationtimeperiod from their associated host or service if not otherwise specified. (Read more)String variables in host, service, and contact definitions can now be prevented from beinginherited by specifying a value of "null" (without quotes) for the value of the variable. (Readmore)Most string variables in local object definitions can now be appended to the string values thatare inherited. This is quite handy in large configurations. (Read more)Performance Improvements:Add ability to precache object config files and exclude circular path detection checks fromverification process. This can speed up Nagios start time immensely in large environments!Read more here.A new use large installation tweaks option has been added that should improve performancein large Nagios installations. Read more about this here.A number of internal improvements have been made with regards to how Nagios deals withinternal data structures and object (e.g. host and service) relationships. These improvementsshould result in a speedup for larger installations.New external command buffer slots option has been added to allow you to more easily scaleNagios in large environments. For best results you should consider using MRTG to graphNagios’ usage of buffer slots over time.Plugin Output:Multiline plugin output is now supported for host and service checks. Hooray! The plugin APIhas been updated to support multiple lines of output in a manner that retains backwardcompatability with older plugins. Additional lines of output (aside from the first line) are nowstored in new LONGHOSTOUTPUT and LONGSERVICEOUTPUT macros.The maximum length of plugin output has been increased to 4K (from around 350 bytes inprevious versions). This 4K limit has been arbitrarily chosen to protect again runaway pluginsthat dump back too much data to Nagios.More information on the plugins, multiline output, and max plugin output length can be foundhere.Service Checks:Nagios now checks for orphaned service checks by default.Added a new enable predictive service dependency checks option to control whether or notNagios will initiate predictive check of service that are being depended upon (in dependencydefinitions). Predictive checks help ensure that the dependency logic is as accurate as possible.(Read more)A new cached service check feature has been implemented that can significantly improveperformance for many people Instead of executing a plugin to check the status of a service,Nagios can often use a cached service check result instead. More information on this can befound here.Host Checks:Host checks are now run in parallel! Host checks used to be run in a serial fashion, whichmeant they were a major holdup in terms of performance. No longer! (Read more)Host check retries are now performed like service check retries. That is to say, host definitionsnow have a new retry interval that specifies how much time to wait before trying the host checkagain. :-)Regularly scheduled host checks now longer hinder performance. In fact, they can help toincrease performance with the new cached check logic (see below).Added a new check for orphaned hosts option to enable checks of orphaned host checks. Thisis need now that host checks are run in parallel.Added a new enable predictive host dependency checks option to control whether or notNagios will initiate predictive check of hosts that are being depended upon (in dependency9

definitions). Predictive checks help ensure that the dependency logic is as accurate as possible.(Read more)A new cached host check feature has been implemented that can significantly improveperformance for many people Instead of executing a plugin to check the status of a host, Nagios canoften use a cached host check result instead. More information on this can be found here.Passive host checks that have a DOWN or UNREACHABLE result can now be automaticallytranslated to their proper state from the point of view of the Nagios instance that receives them. This isvery useful in failover and distributed monitoring setups. More information on passive host check state18.19.20.21.22.23.translation can be found here.Passive host checks normally put a host into a HARD state. This can now be changed byenabling the passive host checks are soft option.Freshness checks:A new freshness threshold latency option has been added to allow to you specify the numberof seconds that should be added to any host or service freshness threshold that is automaticallycalculated by Nagios.IPC:The IPC mechanism that is used to transfer host/service check results back to the Nagiosdaemon from (grand)child processes has changed! This should help to reduce load/latencyissues related to processing large numbers of passive checks in distributed monitoringenvironments.Check results are now transferred by writing check results to files in directory specified by thecheck result path option. Files that are older than the max check result file age option will bemercilessly deleted without further processing.Timeperiods:Timeperiods were overdue for a major overhaul and have finally been extended to allow fordate exceptions, skip dates (every 3 days), etc! This should help you out when definingnotification timeperiods for pager rotations.More information on the new timeperiod directives can be found here and here.Event Broker:Updated NEB API versionModified callback for adaptive program status dataAdded callback for adaptive contact status dataAdded precheck callbacks for hosts and services to allow modules to cancel/override internalhost/service checks.Web Interface:The main splash pages of the web interface are now PHP pages. This will require that youinstall/enable PHP support on your system if it isn’t already.Hostgroup and servicegroup summaries now show important/unimportant problembreakdowns like the TAC CGI.Minor layout changes to host and service detail views in extinfo CGI.New check statistics and have been added to the "Performance Info" screen.Added Splunk integration options to various CGIs. Integration is controlled by theenable splunk integration and splunk url options in the CGI config file.Added new notes url target and action url target options to control what frame notes andaction URLs are opened in.Added new lock author names option to prevent alteration of author names when userssubmit comments, acknowledgements, and scheduled downtime.Debugging Info:The DEBUGx compile options available in the configure script have been removed.Debugging information can now be written to a separate debug file, which is automaticallyrotated when it reaches a user-defined size. This should make debugging problems mucheasier, as you don’t need to recompile Nagios. Full support for writing debugging information10

to file is being added during the alpha development phase, so it may not be complete when youtry it.Variables that affect the debug log are debug file, debug level, debug verbosity, andmax debug file size.24. Update Checks:Nagios will now check approximately once a day to see if a new version is available. This isuseful to keep on top of security patches and new releases. Update notices will appear in theweb interface.Variables that affect the update check are check for updates and bare update check.25. Misc:Temp path variable - A new temp path variable has been added to specify a scratch directorythat Nagios can use for temporary scratch space.Unique notification and event ID numbers - A unique ID number is now assigned to eachhost and service notification. Another unique ID is now assigned to all host and service statechanges as well. The unique IDs can be accessed using the following respective macros: HOSTNOTIFICATIONID , SERVICENOTIFICATIONID , HOSTEVENTID , SERVICEEVENTID , LASTHOSTEVENTID , LASTSERVICEEVENTID .New macros - A few new macros (other than those already mentioned elsewhere above) havebeenadded.Theyinclude HOSTGROUPNAMES , SERVICEGROUPNAMES , HOSTACKAUTHORNAME , HOSTACKAUTHORALIAS , SERVICEACKAUTHORNAME , and SERVICEACKAUTHORALIAS .Reaper frequency - The old service reaper frequency variable has been renamed tocheck result reaper frequency, as it is now also used to process host check results.Max reaper time - A new max check result reaper time variable has been added to limit theamount of time a single reaper event is allowed to run.Fractional intervals - Fractional notification and check intervals (e.g. "3.5" minutes) are nowsupported in host, service, host escalation, and service escalation definitions.Escaped command arguments - You can now pass bang (!) characters in your commandarguments by escaping them with a backslash (\). If you need to include backslashes in yourcommand arguments, they should also be escaped with a backslash.Multiline system command output - Nagios will now read multiple lines out output fromsystem commands it runs (notification scripts, etc.), up to 4K. This matches the limits on pluginoutput mentioned earliar. Output from system commands is not directly processed by Nagios,but support for it is there nonetheless.Better scheduling information - More detailed information is given when Nagios is executedwith the -s command line option. This information can be used to help reduce the time it takesto start/restart Nagios.Aggregated status file updates - The old aggregate status updates option has been removed. Allstatus file updates are now aggregated at a minimum interval of 1 second.New performance data file mode - A new "p" option has been added to thehost perfdata file mode and service perfdata file mode options. This new mode will openthe file in non-blocking read/write mode, which is useful for pipes.Timezone offset - A new use timezone option has been added to allow you to run differentinstances of Nagios in timezones different from the local zone.11

Known IssuesUp To: ContentsSee Also: What’s NewKnown Issues1. Timeperiods:Exclusions and Host/Service Checks - There is a bug in the service/host check scheduling logicthat rears its head when you use timeperiod definitions that use the exclude directive. Theproblem occurs when Nagios Core tries to re-schedule the next check. In this case, thescheduling logic may incorrectly schedule the next check further out in the future than itshould. In essence, it skips over the (missing) logic where it could determine an earlier possibletime using the exception times. Imperfect Solution: Don’t use timeperiod definitions thatexclude other timeperods for your host/service check periods. A fix is being worked on, andwill hopefully make it into a 3.4.x release.12

Advice for BeginnersUp To: ContentsSee Also: Quickstart Installation GuideCongratulations on choosing Nagios! Nagios is quite powerful and flexible, but it can take a lot of workto get it configured just the way you’d like. Once you become familiar with how it works and what it cando for you, you’ll never want to be without it. :-) Here are some important things to keep in mind forfirst-time Nagios users:1. Relax - it’s going to take some time. Don’t expect to be able to get things working exactly the wayyou want them right off the bat. it’s not that easy. Setting up Nagios can involve a bit of work partly because of the options that Nagios offers, partly because you need to know what to monitoron your network (and how best to do it).2. Use the quickstart instructions. The quickstart installation guide is designed to get most new usersup and running with a basic Nagios setup fairly quickly. Within 20 minutes you can have Nagiosinstalled and monitoring your local system. Once that’s complete, you can move on to learning howto configure Nagios to do more.3. Read the documentation. Nagios can be tricky to configure when you’ve got a good grasp of what’sgoing on, and nearly impossible if you don’t. Make sure you read the documentation (particularlythe sections on "Configuring Nagios" and "The Basics"). Save the advanced topics for when you’vegot a good understanding of the basics.4. Seek the help of others. If you’ve read the documentation, reviewed the sample config files, and arestill having problems, send an email message describing your problems to the nagios-users mailinglist. Due to the amount of work that I have to do for this project, I am unable to answer most of thequestions that get sent directly to me, so your best source of help is going to be the mailing list. Ifyou’ve done some background reading and you provide a good problem description, odds are thatsomeone will give you some pointers on getting things working properly. More information onsubscribing to the mailing lists or searching the list archives can be found athttp://www.nagios.org/support/.13

Nagios Quickstart Installation GuidesUp To: ContentsSee Also: Upgrading Nagios, Configuration Overview, Security ConsiderationsAbout NagiosVisit www.nagios.org/about/ for more information on Nagios - including features, capabilities, andtechnical specifications.Installation IntroductionThese quickstart guides are intended to provide you with simple instructions on how to install Nagiosfrom source (code) and have it monitoring your local machine inside of 20 minutes. No advancedinstallation options are discussed here - just the basics that will work for 95% of users who want to getstarted.Installation GuidesQuickstart installation guides are currently available for the following Linux distributions:Fedora QuickstartopenSUSE QuickstartUbuntu QuickstartYou can also find additional quickstart guides on the Nagios Community Wiki. Can’t find a quickstartfor your particular OS? Write one and post it to the wiki for others!If you are installing Nagios on an operating system or Linux distribution that isn’t listed above, read theFedora quickstart for an overview of what you’ll need to do. Command names, paths, etc. vary widelyacross different OSes/distributions, so you’ll likely need to tweak the installation docs a bit to work foryour particular case.Post-Installation ModificationsOnce you get Nagios installed and running properly, you’ll no doubt want to start monitoring morethan just your local machine. Check out the following docs for how to go about monitoring otherthings.Monitoring Windows machinesMonitoring Linux/Unix machinesMonitoring Netware serversMonitoring routers/switchesMonitoring network printersMonitoring publicly available services (HTTP, FTP, SSH, etc.)14

Enhance Nagios With Community Addo

Embedded Perl: Added new enable_embedded_perl and use_embedded_perl_implicitly variables to control use of the embedded Perl interpreter. Perl scripts/plugins can now explicitly tell Nagios whether or not they should be run under the embedded Pel interpreter. This is useful if you have troublesome scripts that don't function well under the ePN. 7