book

Nagios, 2nd Edition

Name: Nagios, 2nd Edition
Author: Wolfgang Barth
ISBN: 9781593271794

by Wolfgang Barth

October 2008

Intermediate to advanced

720 pages

16h 7m

English

No Starch Press

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Nagios: System and Network Monitoring, 2nd Edition
Foreword to the second edition
What's New in the Second Edition?
Information Sources on the Internet
Introduction
The tests
The suppliers of information
Keeping admins up-to-date
Taking in information from outside
Other tools for network monitoring
About This Book
Further notes on the book

Note of Thanks
I. From Source Code to a Running Installation
1. Installation
1.1 Preparations1.1.1 Determining and setting up the required users
1.2 Compiling Source Code
1.3 Starting Nagios Automatically
1.4 Installing and Testing Plugins
1.4.1 Installation1.4.2 Plugin test
1.5 Configuration of the Web Interface
1.5.1 Setting up Apache1.5.2 SELinux1.5.3 User authentication
2. Nagios Configuration
2.1 The Main Configuration File nagios.cfgSimple structureSimple structureA larger locationLarge installations with several different locationsSetting the European date format
2.2 Objects—an Overview
Notes on the object examples belowNotes on the object examples below
2.3 Defining the Machines to Be Monitored, with host
2.4 Grouping Computers Together with hostgroup
2.5 Defining Services to Be Monitored with service
2.6 Grouping Services Together with servicegroup
2.7 Defining Addressees for Error Messages: contact
2.8 The Message Recipient: contactgroup
2.9 When Nagios Needs to Do Something: The command Object
2.10 Defining a Time Period with timeperiod
2.11 Templates
2.12 Configuration Aids for Those Too Lazy to Type
2.12.1 Defining services for several computers2.12.2 One host group for all computers2.12.3 Other configuration aids
2.13 CGI Configuration in cgi.cfg
2.14 The Resources File resource.cfg
3. Startup
3.1 Checking the Configuration
3.2 Getting Monitoring Started
3.2.1 Manual start3.2.2 Making configuration changes come into effect
3.3 Overview of the Web Interface
II. In More Detail...
4. Nagios Basics
4.1 Taking into Account the Network Topology
4.2 On-Demand Host Checks vs. Periodic Reachability Tests
4.3 States of Hosts and Services
5. Service Checks and How They Are Performed
5.1 Testing Network Services Directly
5.2 Running Plugins via Secure Shell on the Remote Computer
5.3 The Nagios Remote Plugin Executor
5.4 Monitoring via SNMP
5.5 The Nagios Service Check Acceptor
6. Plugins for Network Services
6.1 Standard Options
6.2 Reachability Test with Ping
6.2.1 check_icmp as a Service Check6.2.2 check_icmp as a Host Check
6.3 Monitoring Mail Servers
6.3.1 Monitoring SMTP with check_smtp6.3.2 POP and IMAP
6.4 Monitoring FTP and Web Servers
6.4.1 FTP services6.4.2 Web server control via HTTP6.4.3 Monitoring Web proxiesProxy test with check_httpProxy test with check_squid
6.5 Domain Name Server Under Control
6.5.1 DNS check with nslookup
6.5.2 Monitoring the name server with dig
6.6 Querying the Secure Shell Server
6.7 Generic Network Plugins
6.7.1 Testing TCP ports
6.7.2 Monitoring UDP ports
6.8 Monitoring Databases
6.8.1 PostgreSQLConfiguring a monitor-friendly DBMSThe test plugin check_pgsql6.8.2 MySQLMySQL configurationThe test plugin check_mysql
6.9 Monitoring LDAP Directory Services
6.10 Checking a DHCP Server
Granting the plugin root permissionsGranting the plugin root permissionsApplying the plugin
6.11 Monitoring UPS with the Network UPS Tools
The Network UPS ToolsThe Network UPS ToolsThe check_ups plugin
6.12 Health Check of an NTP Server with check_ntp_peer
7. Testing Local Resources
7.1 Free Hard Drive Capacity
7.2 Utilization of the Swap Space
7.3 Testing the System Load
7.4 Monitoring Processes
7.5 Checking Log Files
7.5.1 The standard plugin check.log7.5.2 The modern variation: check_logs.pl7.5.3 The Swiss Army knife: check_logfilesConfiguration Files
7.6 Keeping Tabs on the Number of Logged-In Users
7.7 Checking the System Time
7.7.1 Checking the system time via NTP7.7.2 Checking system time with the time protocol
7.8 Regularly Checking the Status of the Mail Queue
7.9 Keeping an Eye on the Modification Date of a File
7.10 Monitoring UPSs with apcupsd
7.11 Nagios Monitors Itself
7.11.1 Running the plugin manually with a script
7.12 Hardware Checks with LM Sensors
8. Plugins for Special Tasks
8.1 The Dummy Plugin for Tests
8.2 Negating Plugin Results
8.3 Inserting Hyperlinks with urlize
8.4 Checking Host or Service Clusters as an Entity
8.5 Summarizing Checks with check_multi
8.5.1 Multiple-line plugin output8.5.2 Installation requirementsAdjusting buffer sizes for NRPEAdjusting buffer sizes for check_by_ssh8.5.3 Installation and testing8.5.4 Configuration file8.5.5 Command-line parameters8.5.6 Performance data and PNP8.5.7 Simple business process monitoring
9. Executing Plugins via SSH
9.1 The check_by_ssh Plugin
9.2 Configuring SSH
9.2.1 Generating SSH key pairs on the Nagios server9.2.2 Setting up the user nagios on the target host9.2.3 Checking the SSH connection and check_by_ssh
9.3 Nagios Configuration
10. The Nagios Remote Plugin Executor (NRPE)
10.1 Installation10.1.1 Distribution-specific packages10.1.2 Installation from the source code
10.2 Starting via the inet Daemon
10.2.1 xinetd configuration10.2.2 inetd configurationt10.2.3 Is the Inet daemon watching on the NRPE port?
10.3 NRPE Configuration on the Computer to Be Monitored
10.3.1 Passing parameters on to local plugins
10.4 NRPE Function Test
10.5 Nagios Configuration
10.5.1 NRPE without passing parameters on10.5.2 Passing parameters on in NRPE10.5.3 Optimizing the configuration
10.6 Indirect Checks
11. Collecting Information Relevant for Monitoring with SNMP
11.1 Introduction to SNMP11.1.1 The Management Information BaseMIB-II11.1.2 SNMP protocol versions
11.2 NET-SNMP
11.2.1 Tools for SNMP requestsTaking a graphic walk with mbrowse11.2.2 The NET-SNMP daemonSupported Mangement Information BasesThe configuration file snmpd.conf
11.3 Nagios's Own SNMP Plugins
11.3.1 The generic SNMP plugin check_snmpTesting hard drive capacity via SNMPMeasuring temperature via lm-sensorsRegular expressions and comparing fixed stringsMonitoring network interfaces11.3.2 Checking several interfaces simultaneously11.3.3 Testing the operating status of individual interfaces
11.4 Other SNMP-based Plugins
11.4.1 Monitoring hard drive space and processes with nagios-snmp-plugins11.4.2 Observing the load on network interfaces with check-iftraffic11.4.3 The manubulon.com plugins for special application purposesKeeping checks on storage media with check_snmp_storageTesting system load with check_snmp_load
12. The Nagios Notification System
12.1 Who Should be Informed of What, When?
12.2 When Does a Message Occur?
12.3 The Message Filter
12.3.1 Switching messages on and off systemwide12.3.2 Enabling and suppressing computer and service-related messagesTaking downtimes into accountWhat states and changes of state are worth a notification?When should Nagios send messages?Whose concern is the message?12.3.3 Person-related filter optionsWhat should Nagios inform you about?When do messages reach the recipient?12.3.4 Case examplesLetting you know once, but doing this reliablyInforming different admins at different times
12.4 External Notification Programs
12.4.1 Notification via e-mail12.4.2 Notification via SMSSetting up smsclientGetting Nagios to work together with smsclient
12.5 Escalation Management
12.6 Accounting for Dependencies between Hosts and Services
12.6.1 The standard case: service dependenciesInheritanceOther application casesAdditional functions in Nagios 3.012.6.2 Only in exceptional cases: host dependencies
13. Passive Tests with the External Command File
13.1 The Interface for External Commands
13.2 Passive Service Checks
13.3 Passive Host Checks
13.4 Reacting to Out-of-Date Information of Passive Checks
14. The Nagios Service Check Acceptor (NSCA)
14.1 Installation
14.2 Configuring the Nagios Server
14.2.1 The configuration file nsca.cfg14.2.2 Configuring the inet daemonxinetd configurationinetd configuration
14.3 Client-side Configuration
14.4 Sending Test Results to the Server
14.5 Application Example I: Integrating syslog and Nagios
14.5.1 Preparing syslog-ng for use with Nagios14.5.2 Nagios configuration: volatile services14.5.3 Resetting error states manually
14.6 Application Example II: Processing SNMP Traps
14.6.1 Receiving traps with snmptrapd14.6.2 Passing on traps to NSCA14.6.3 The matching service definition
15. Distributed Monitoring
15.1 Switching On the OCSP/OCHP Mechanism
15.2 Defining OCSP/OCHP Commands
15.3 Practical Scenarios
15.3.1 Avoiding redundancy in configuration files15.3.2 Defining templates
III. The Web Interface and Other Ways to Visualize Nagios Data
16. The Classical Web Interface
16.1 Recognizing and Acting On Problems16.1.1 Comments on problematic hosts16.1.2 Taking responsibility for problems
16.2 An Overview of the Individual CGI Programs
16.2.1 Variations in status display: status.cgi16.2.2 Additional information and control center: extinfo.cgi16.2.3 Interface for external commands: cmd.cgi16.2.4 The most important things at a glance: tac.cgi16.2.5 The topological map of the network: statusmap.cgi16.2.6 Navigation in 3D: statuswrl.cgi16.2.7 Querying the status with a cell phone: statuswml.cgi16.2.8 Analyzing disrupted partial networks: outages.cgi16.2.9 Querying the object definition with config.cgi16.2.10 Availability statistics: avail.cgi16.2.11 What events occur, how often?—histogram.Cgi16.2.12 Filtering log entries after specific states: history.cgi16.2.13 Who was told what, when?— notifications.Cgi16.2.14 Showing all log file entries: showlog.cgi16.2.15 Evaluating whatever you want: summary.cgi16.2.16 Following states graphically over time: trends.Cgi
16.3 Planning Downtimes
16.3.1 Maintenance periods for hosts16.3.2 Downtime for services
16.4 Additional Information on Hosts and Services
16.4.1 Extended host information16.4.2 Extended service information
16.5 Configuration Changes through the Web Interfaces: the Restart Problem
16.6 Modern Layout with the Nuvola Style
17. Flexible Web Interface with the NDOUtils
17.1 The Event Broker
17.2 The Database Interface
17.3 The Installation
17.3.1 Compiling the source code17.3.2 Preparing the MySQL database17.3.3 Upgrading the database design
17.4 Configuration
17.4.1 Adjusting the Event Broker configuration17.4.2 Configuring database access17.4.3 Starting the ndo2db daemon17.4.4 Loading the Event Broker module in Nagios
18. NagVis
18.1 Installation18.1.1 Installing the source code18.1.2 Initial configuration18.1.3 User authentication
18.2 Creating NagVis Maps
18.2.1 Editing the configuration in text form18.2.2 Adding NagVis maps to the Nagios Web interface
19. Graphic Display of Performance Data
19.1 Processing Plugin Performance Data with Nagios19.1.1 The template mechanism19.1.2 Using external commands to process performance data
19.2 Graphs for the Web with Nagiosgraph
19.2.1 Basic installation19.2.2 ConfigurationThe configuration file nagiosgraph.confNagios configurationApache configurationAdjustments to the map
19.3 Preparing Performance Data for Evaluation with Perf2rrd
19.3.1 Installation19.3.2 Nagios configuration19.3.3 Perf2rrd in practicePerf2rrd in permanent operation
19.4 The Graphics Specialist drraw
19.4.1 Installation19.4.2 Configuration19.4.3 Practical application
19.5 Automated to a Large Extent: NagiosGrapher
19.5.1 Installation19.5.2 ConfigurationThe configuration file ngraph.ncfgConfiguring the graphics—the basic principleAdvanced options of graphic reprocessingNagios configuration
19.6 Smooth Plotting with PNP
19.6.1 Installation19.6.2 The standard configurationAdjusting the Nagios configuration19.6.3 The PNP Web interfaceIntegrating PNP into the Nagios Web interface19.6.4 Bulk processing of performance data19.6.5 How should the graphic appear?Custom Templates
19.7 Other Tools and the Limits of Graphic Evaluation
IV. Part IV Special Applications
20. Monitoring Windows Servers
20.1 Agent-less Checks via WMI
20.2 Installing and Configuring the Additional Services
20.2.1 NSClient20.2.2 NC_Net20.2.3 NSClient++InstallationConfiguration20.2.4 OpMon Agent20.2.5 Rectifying problems with port 1248
20.3 The check_nt Plugin
20.3.1 Generally supported commandsQuerying the client versionCPU loadMain memory usageHard drive capacityUptimeStatus of servicesStatus of processesAge of filesQuerying Windows counters and instances20.3.2 Advanced functions of NC_Net20.3.3 Installing the check_ncnet pluginWindows Performance CounterListing processes and servicesQuerying the Windows event logDisplaying and manipulating the NC_Net configurationOther functions
20.4 NRPE for Windows
20.4.1 NRPE_NT, the classic toolFunction test20.4.2 Plugins for NRPE in WindowsThe Cygwin pluginsPerl plugins in Windows20.4.3 NRPE with NSClient++20.4.4 Internal NSClient++ functionsChecking file sizes with CheckFileSizeChecking how full drives are with CheckDriveSizeChecking CPU load with CheckCPUDetermining the uptime with CheckUpTimeActivity check with CheckServiceStateMonitoring processes with CheckProcStateChecking memory load with CheckMemChecking the performance counter with CheckCounterEvaluating log entries with CheckEventLogThe debug functions CheckAlwaysOK, CheckAlwaysWARNING, and CheckAlwaysCRITICALSummarizing several checks with CheckMultiple
21. Monitoring Room Temperature and Humidity
21.1 Sensors and Software21.1.1 The PCMeasure software for Linux21.1.2 The query protocol
21.2 The Nagios Plugin check_pcmeasure2.pl
22. Monitoring SAP Systems
22.1 Checking without a Login: sapinfo22.1.1 Installation22.1.2 First test22.1.3 The plugin check_sap.sh22.1.4 More up to date and written in Perl: check_sap.pl
22.2 Monitoring with SAP's Own Monitoring System CCMS
22.2.1 A short overview over the alert monitor22.2.2 Obtaining the necessary SAP usage permissions for Nagios22.2.3 Monitors and templates22.2.4 The CCMS pluginsFirst steps with check_sap_consChecking multiple values with check_sap_mult_no_thr22.2.5 Performance optimization
23. Processing Events with the EventDB
23.1 How the EventDB Works
23.2 Installation
23.2.1 Installation requirements23.2.2 Preparing the MySQL database23.2.3 Sending events to the database with syslog-ng
23.3 Using the Web Interface
23.3.1 Preselection of the filter with URL parameters23.4 The Nagios Plugin for the EventDB
23.5 Maintenance
23.6 Sending Windows Events to Syslog
23.7 Making the Incomprehensible Legible with SNMPTT
23.7.1 The configuration file snmptt.ini23.7.2 Converting MIBs
V. Part V Development
24. Writing Your Own Plugins
24.1 Programming Guidelines for Plugins24.1.1 Return values24.1.2 Information for the administrator on the standard output24.1.3 Onboard online help?24.1.4 Reserved options24.1.5 Specifying thresholds24.1.6 Timeout24.1.7 Performance data24.1.8 Copyright
24.2 The Perl Module Nagios::Plugin
24.2.1 InstallationThe method using the CPANTogether with the core plugins
25. Determining File and Directory Sizes
25.1 Splitting up the Command Line With Getopt::Long
25.2 The Perl Online Documentation
25.2.1 The module Pod::Usage
25.3 Determining Thresholds
25.4 Implementing Timeouts
25.5 Displaying Performance Data
25.6 Configuration Files for Plugins
26. Monitoring Oracle with the Instant Client
26.1 Installing the Oracle Instant Client
26.2 Establishing a Connection to the Oracle Database
26.3 A Wrapper Plugin for sqlplus
26.3.1 How the wrapper works26.3.2 The Perl plugin in detail
VI. Part VI Appendixes
A. An Overview of the Nagios Configuration Parameters
A.1 The Main Configuration File nagios.cfg
A.2 CGI Configuration in cgi.cfg
A.2.1 Authentication parametersA.2.2 Other Parameters
B. Rapidly Alternating States: Flapping
B.1 Flap Detection with ServicesB.1.1 Nagios configurationB.1.2 The history memory and the chronological progression of the changes in stateB.1.3 Representation in the Web interface
B.2 Flap Detection for Hosts
C. Event Handlers
C.1 Execution Times for the Event Handler
C.2 Defining the Event Handler in the Service Definition
C.3 The Handler Script
C.4 Things to Note When Using Event Handlers
D. Macros
D.1 Standard MacrosD.1.1 Host macrosD.1.2 Service macrosD.1.3 Group macrosD.1.4 Contact macrosD.1.5 Notification macrosD.1.6 Macros to specify time and dateD.1.7 Statistics macrosD.1.8 Using standard macros about the environment
D.2 On-Demand Macros
D.3 Macros for User-defined Variables
D.4 Macro Contents: Not Everything Is Allowed
E. Single Sign-On for the Nagios Web Interface
E.1 HTTP Authentication for Single Sign-On
E.2 Kerberos Authentication with mod_auth_kerb
E.2.1 InstallationE.2.2 Creating a service ticket for ApacheE.2.3 Kerberos configurationE.2.4 Apache configurationE.2.5 Definition of a Nagios contact
E.3 Single Sign-On with mod_auth_ntlm_winbind
E.3.1 InstallationE.3.2 Preparing SambaE.3.3 Apache configurationE.3.4 Defining a Nagios contact
E.4 Mozilla Firefox as a Web Client
E.4.1 Firefox and NTLM
E.5 Microsoft Internet Explorer as a Web Client
F. Tips on Optimizing Performance
F.1 Internal Statistics of NagiosF.1.1 The command-line tool nagiostatsDetermining single valuesF.1.2 Showing Nagios performance graphicallyF.1.3 A plugin to monitor latency
F.2 Measures for Improving Performance
F.2.1 Service checks: as often as necessary, as few as possibleF.2.2 Processing performance data intelligentlyF.2.3 Avoiding plugins in interpreted languagesF.2.4 Optimizing host checksF.2.5 The matter of the Reaper
F.2.6 Preferring passive checks
F.2.7 Optimizing large Nagios environmentsF.2.8 Optimizing the NDOUtils database
G. The Embedded Perl Interpreter
G.1 Requirements of an ePN-capable Plugin
G.2 Using ePN
G.2.1 Compiling ePNG.2.2 Interpreter-specific parameters in nagios.cfgG.2.3 Disabling ePN on a per-plugin basis
G.3 The Testing Tool new_mini_epn
H. What's New in Nagios 3.0?
H.1 Changes in Object DefinitionsH.1.1 The host objectExtended host informationH.1.2 The service objectH.1.3 Group objectsH.1.4 The contact objectH.1.5 Time definitionsH.1.6 Dependency descriptionsH.1.7 Escalation objectsH.1.8 Inheritance
H.2 Variable and Macros
H.3 Downtime, Comments, and Acknowledgments
H.4 Rapidly Changing States
H.5 External Commands
H.6 Embedded Perl
H.7 A New Logic for Host Checks
H.8 Restart
H.9 Performance Optimization
H.10 Extended Plugin Output
H.11 CGI
H.12 Miscellaneous
H.13 Upgrade from Nagios 2.x to 3.0

Content preview from Nagios, 2nd Edition

8.4 Checking Host or Service Clusters as an Entity

Plugins normally check an individual host or service, compare the result with the specified thresholds, and then return an appropriate result. On systems with redundant designs (such as in clusters) you can also check the respective host or service individually. In addition, a check of the virtual host or service provides a clue as to whether or not the virtual system as a whole is reachable. The plugin check_cluster allows more complex values to be queried.

As an example, we will take a host cluster consisting of five identical single systems. One of these hosts may fail without any problem, but if a second one fails, the plugin should issue a WARNING. If a third host should fail, a CRITICAL should ...

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Nagios, 2nd Edition

by Wolfgang Barth

8.4 Checking Host or Service Clusters as an Entity

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