Nagios - Network Management & Monitoring

Course Overview

This practical guide focuses on deploying, configuring, and operating Nagios to achieve reliable network monitoring and actionable alerting. It emphasizes repeatable configuration patterns, clear notification workflows, and pragmatic performance tuning so teams can maintain visibility across mixed infrastructure while reducing false alarms and repair time. Examples and recommendations are presented with production-ready clarity, helping administrators move from basic installation to scalable, maintainable monitoring setups.

What you will learn

• How Nagios core elements (scheduler, broker, check commands, and plugins) interact to report host and service health and trigger notifications.
• Practical configuration patterns for hosts, services, hostgroups, templates, contacts, and notification rules that reduce duplication and improve consistency.
• Which configuration directives influence check intervals, timeouts, and parallelism, and how to structure include files for safer reloads.
• Alerting best practices: mapping contacts and contactgroups, composing notification commands, and sequencing escalations so alerts reach the right responders.
• Strategies for scaling Nagios: passive checks, event handlers, resource planning, and approaches for distributed or proxy-based monitoring.

Topics and practical coverage

The guide progresses from installation and core concepts into concrete, copy-ready configuration examples. It shows how to declare hosts and services using define host and define service blocks, apply templates for inheritance, and group hosts to simplify policy changes. Example checks span standard network services (HTTP, SSH, FTP) and demonstrate how to register custom plugins so you can monitor proprietary systems or application-specific metrics.

Operational sections cover reliable alerting: contact and contactgroup mapping, notification command definitions, and escalation chains are explained with examples that make on-call routing predictable and actionable. Event handlers and automated recovery actions are presented as ways to reduce manual work and lower mean time to repair, with guidance on when to automate versus when to notify humans.

Performance tuning and scale

Actionable tuning advice targets medium-to-large environments: tune check intervals and parallel check limits, migrate appropriate checks from active to passive mode, and organize configuration includes to minimize reload impact. The text recommends ways to measure system load, prioritize checks by importance, and plan for distributed architectures to preserve responsiveness as monitoring footprint grows.

Hands-on projects and exercises

Exercises reinforce core concepts through a sequence of practical labs: deploy a basic Nagios instance, create reusable templates and command definitions, write and register a custom plugin script, and implement escalation-based notifications. Labs emphasize repeatability and safe testing practices so you can validate changes before applying them to production.

Who should use this guide

Designed for system administrators, network engineers, and DevOps practitioners, this resource suits those new to Nagios as well as intermediate users seeking performance and alerting improvements. It is most useful for teams that require clear operational guidance, reproducible configuration patterns, and practical scaling strategies.

How to use the guide effectively

Reproduce the initial examples in an isolated test environment, adapt templates and command definitions to your naming conventions, and apply tuning changes incrementally while observing load and check latency. Use the guide's glossary-style explanations to standardize terminology and avoid configuration mistakes across your team.

Quick FAQ

How are hosts and services defined?

Use define host and define service blocks in configuration files. Key attributes include host_name, address, templates for inheritance, and check commands that invoke plugins.

When should I write a custom plugin?

Create a custom plugin when built-in checks don’t cover your application or when you need bespoke metrics. Place executable scripts in the plugins directory and register them with a define command so Nagios can execute and interpret their results.

Overall, this guide delivers example-rich, operationally focused instruction to help teams build and maintain reliable Nagios monitoring—prioritizing clear alerting, reusable configuration practices, and scalable performance techniques.