Information Density: Nagios – Signal Evidence & AI Readability

[H2] Popular Open Source Projects
Production-ready monitoring trusted by thousands of organizations worldwide.
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[H3] Nagios Core
The monitoring engine that started it all. Monitor websites, servers, switches, routers, firewalls, ports, applications, metrics, and more.
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[H3] NCPA (Nagios Cross-Platform Agent)
Monitor Windows, Linux, and Mac in real time. NCPA is a cross-platform agent for servers, system metrics, applications, and networks.
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[H3] Nagios Plugins
50+ ready-made checks packaged with Nagios including check_ping, check_ssh, check_cpu, check_memory, check_linux, and more.
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[H3] Nagios Mod-Gearman
Adds scalability and performance to Nagios Core, enabling users of Nagios Core and XI to effectively monitor large environments.
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[H3] Nagios Configuration Tools
Web UIs, auto-discovery scripts & change management interfaces to simplify Nagios configuration without manual file editing.
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[H3] Nagios Visualization Add-ons
Transform Nagios data into dashboards, network maps & performance graphs for intuitive monitoring and business insights.
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[H1] Nagios Cross-Platform Agent
The Nagios Cross-Platform Agent (NCPA) is an open-source monitoring tool that delivers comprehensive monitoring for Windows, Linux, and Mac OS X. It offers active/passive checks, real-time metrics, and custom plugin support through an intuitive web interface.
Download NCPA

Explore NCPA Documentation
NCPA Checks - Nagios Cross-Platform Agent Monitoring
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[H2] All-in-One Monitoring with NCPA
Analyze real-time metrics, test API functionality, identify resource-heavy processes, and utilize custom plugins —all from one intuitive platform.
Live Stats
API Browser
Top Processes
Integrated Docs
[H3] Real-Time Metrics for Complete System Visibility
Instant insights into CPU, memory, disk, and network usage with real-time graphs. Identify and resolve performance issues quickly to maintain optimal system health.
[IMG: Screenshot of the NCPA Live Stats tab showcasing real-time graphing API with dynamic graphs for CPU, memory, disk, and interface metrics, powered by WebSocket technology. Ideal for integration with Nagios XI or standalone API calls.]
[H3] Customizable Monitoring with API Testing
Develop and test custom plugins directly in the web interface. The built-in API browser makes extending NCPA’s capabilities simple and efficient.
[IMG: Screenshot of the NCPA API browser, accessible through the web GUI, designed for learning and testing API calls. Includes tool-tip guidance, custom plugin testing, and check examples for streamlined production use.]
[H3] Easily Track Resource-Intensive Processes
Monitor active processes across operating systems to pinpoint resource-hungry applications. Stay informed and take action to optimize performance.
[IMG: Screenshot of the NCPA web GUI displaying real-time top processes, similar to the Linux]
[H2] Comprehensive Guidance at Your Fingertips
Access detailed documentation directly within the interface. Configure, troubleshoot, and maximize NCPA’s features with step-by-step guidance.
[IMG: Screenshot of the integrated help documentation in the NCPA web GUI, providing comprehensive guidance on using NCPA features and sections with detailed explanations and ongoing updates.]
[H2] Why Choose NCPA for IT Monitoring?

[H2] Cross-Platform Monitoring
NCPA is developed in Python, enabling it to operate seamlessly on various operating systems. Official binaries are available for Windows, Mac OS X, and multiple Linux distributions.
[H2] Active & Passive Checks
Utilize the check_ncpa.py plugin for active checks or configure passive checks to send data to any NRDP server, providing flexibility to meet your organization’s monitoring requirements.
[H2] Real-time Graphing API
Leverage real-time graphing capabilities to monitor server statistics such as CPU, memory, disk, and network usage, facilitating immediate insights into system performance.
[H2] Custom Plugin Support
Easily integrate your own Nagios-compatible plugins with NCPA. Execute custom plugins via the API, as active checks, or as passive checks, tailoring the monitoring system to your specific needs.
[H2] Extensive Web GUI
The integrated web GUI allows you to browse the API, access comprehensive documentation, view system information, configure settings, and generate real-time graphs, all within an intuitive interface.
[H2] Bundled Dependencies
NCPA packages all necessary dependencies, including Python and required modules, into a single installable agent, simplifying setup and eliminating compatibility concerns.
[H2] Download NCPA
View the changelog to see a list of all features and bug fixes.
Don’t see your version of OS on this list? Visit our GitHub to build it for your own distribution!
Platform Compatibility Table
Platform
Compatibility
Installation Method
Windows
Windows 10+, Windows Server 2016+
EXE Installer - 64-bit
RPM Linux
EL8+, SuSE 15+
Install Using Nagios Repo - RPM
Download RPM 64-bit
DEB Linux
Debian 11+, Ubuntu 22+
Install Using Nagios Repo - DEB
Download DEB - 64-bit
MacOS X
MacOS 13+
DMG Installer - 64-bit
Solaris
11.4 SRU81
Download PKG - x86
Download PKG - SPARC
AIX
AIX 7.3 TL4
Download RPM - AIX
NOTE: before upgrading to NCPA 3 from NCPA 2 on Linux, you must upgrade your GPG key as can be seen at repo.nagios.com.
[H2] Other Downloads
[H2] Nagios Plugins
For active checks. Version: 1.2.4: Download check_ncpa.py
[H2] Archived Versions
Download the older versions of NCPA. Go to download archive.
[H2] Development Builds
Access the latest dev builds. These builds are not meant for production.
[H2] Documentation
[H2] Getting Started Guide
Want to see NCPA in action? Start using NCPA to monitor your own environment with these quick-start guides. Get started with:
Windows  ·    Linux  ·   Mac  ·  Solaris  ·  AIX
[H2] Other Documents
Here are some links to documents that relate to NCPA that are more in-depth than the getting started guide.
Setting up NCPA Development EnvironmentBuilding NCPA Binaries
[H2] Help Reference
Read the help documentation that comes standard in the NCPA. You can also view this in any NCPA GUI by clicking the Help tab.
View latest help reference
[H2] FAQ

Can I use NCPA with Nagios Core?
Of course! While we built NCPA with Nagios XI in mind (due to some awesome integration via the NCPA config wizard) but the agent can send passive checks to Nagios Core or use our check_ncpa.py plugin to run active checks from Nagios Core.
Why did you choose Python?
Python is a very flexible language. It can be used on most operating systems and when we wanted to be able to run our binaries without any requirements, it's modular layout pairs perfectly with it's small footprint. Python also has a large community and is a very popular language.
I read your license, can I fork the NCPA GitHub repo to make a pull request?
While the Nagios Open Source Software License may seem rather restricting, we want to work together by collaborating with the community. You may fork the NCPA GitHub repository to contribute to the development of NCPA. However, you cannot fork the code to create a competing product.
Where should I report bugs?
The quickest way to get in contact with the developers is by creating an issue on the project's GitHub issues page. Try to be as descriptive as possible so we can reproduce the bug and fix it.
It's been a while since the last update, is the project still being developed?
Yes, it is. You may have noticed that NCPA has periods of active daily development and periods where there may be hardly any development from the Nagios developers. This is a true open source project for the Nagios developers and we don't normally work on it during the business work day. We are normally busy making cool new features and squashing bugs in the variety of enterprise monitoring products that Nagios Enterprises offers. This means 95% of all NCPA development is done on the developer's own time. With that said, we will try to respond to any issues on GitHub as quickly as possible, so don't be shy.
[H2] Project
The origins of NCPA can be traced back to the 2012 Nagios World Conference, where a network admin stated, “I have no idea why agents are so difficult”. After reflecting on the statement, we had no answer. The idea for NCPA to be a single monitoring agent that was secure, simple, and easy to manage was formed.In 2014, the first version of NCPA was released with the basic features that are core to the project such as the cross-platform API.
Today, NCPA has come a long way from the initial idea back in 2014. It includes countless extra features with many more under development.
If you’d like to get involved with development, check out the contributing guide on GitHub. If you’re not a developer, but would like to help in other ways, feel free to give your feedback and comments in the issues section of the project.

[H2] The #1 Open Source Monitoring Solution For IT
Nagios Core has been downloaded  millions of times for good reason – it’s the industry standard in open source monitoring for all environments, large and small.
[H3] Websites & Web Applications
Monitor uptime, response time, SSL certificates, content changes
[H3] Servers & Workstations
Track CPU, memory, disk usage, running processes, system health
[H3] Network Infrastructure
Monitor switches, routers, firewalls, ports, bandwidth, traffic
[H3] Applications & Services
Database servers, email systems, DNS, DHCP, custom applications
[H3] Cloud Infrastructure
AWS, Azure, Google Cloud, and other cloud platforms
[H3] Custom Metrics
Anything you can measure with a script or plugin

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[H1] Making the Switch to a Better Monitoring Solution
Enjoying the power of Nagios Core? Upgrade to Nagios XI.
Nagios XI is built on Core, but automates the work you’re doing manually—like configurations, alerts, and reporting. Get more done in less time, without needing to dig into command lines every day.
Switch to Nagios XI
[IMG: xi dashboard no head 1]
Why Switch?
How To Migrate
Resources
[H2] Why Switch?
[H3] Wizards Make Setup Faster and Easier.
You’ve mastered Nagios Core and scripting is second nature. But what if you could spend less time setting things up and more time focusing on what matters? Nagios XI goes far beyond Core. Nagios XI offers a fully integrated platform with easy-to-use Configuration Wizards, pre-installed integrations, and an intuitive dashboard, all designed to take the hassle out of monitoring so you can get more done, faster.
[H3] Effortless Setup
No need to dive into manual configurations— Nagios Configuration Wizards handle the setup for you, but you still have the flexibility to tweak things your way.
Learn More About Nagios XI
[H3] Custom Dashboards & Insights
Get a complete view of your environment with highly customizable dashboards and built-in performance graphs—no extra steps required.
Learn More About Nagios XI
[H3] Smarter Reporting
Access powerful reports and visualizations that give you deeper insights, without manual effort.
Learn More About Nagios XI
[H2] How to Migrate
Migrating from Nagios Core to  XI involves a few key steps to get you up and running. We’ve outlined the main steps here to help guide you through the process.For a deeper dive into the migration, check out our Roadmap for Making the Upgrade From Core to XI , and if you need more detailed instructions, be sure to visit our full guide to Migrating From Core to XI.
For advanced setups, like distributed monitoring environments, additional configuration may be needed. Please refer to our documentation for more details.
[IMG: info]
You can now automatically migrate Nagios Core data to Nagios XI. See Automatic Nagios Core Migration to Nagios XI for more information.
[H3] 1. Deploy a New Nagios XI instance
In order to migrate from Nagios Core to Nagios XI, you should deploy a clean installation of Nagios XI to a different physical server or virtual machine than what is used for your existing Nagios Core installation. This allows you to migrate settings to XI and test the new monitoring setup before decommissioning your old server.
[H3] 2. Upload Plugins and Scripts to Nagios XI
To use your custom plugins and scripts in Nagios XI, you’ll need to upload them to the /usr/local/nagios/libexec directory. You can do this easily through the XI web interface under the Admin menu. For more details, check out the Managing Plugins in Nagios XI guide. Custom event handlers or notification scripts should also be placed in the same directory or in a subfolder like /eventhandlers.
[H3] 3. Import Nagios Core Configuration Files to Nagios XI
When migrating to Nagios XI, you can bring over your Nagios Core configuration files, including hosts, services, commands, and more. You have two options: manually maintain the configuration files or import them into the Core Config Manager (CCM) database. You can also mix and match—starting with manual files and importing later, or importing some files while keeping others manually maintained.
[H4] Option 1: Manually Maintained Config Files
Manually-maintained configuration files should be stored in the /usr/local/nagios/etc/static directory on your Nagios XI server. If you prefer to maintain your configuration files manually instead of importing them into the web configuration database, refer to the related documentation for more details.
[H4] Option 2: Importing Config Files
[H4] Prepare Import
Before importing, use the Nagios Config Import Prep Tool.
[H4] Import Configuration Files
Navigate to the Core Config Manager (CCM), then go to Tools > Import Config Files. Import in the correct order, ensuring all required objects exist.
[H4] Validate and Adjust
After importing, validate your configuration files before applying changes.
[H4] Apply Configuration
Once verified, use the Apply Configuration option to restart Nagios Core with the new setup.
[H3] 4. Add User Accounts To The Nagios XI Server
After migrating your Nagios Core configurations to Nagios XI, you’ll need to add user accounts for access to the XI web interface. You can create new users through Admin > Users > Manage Users. Nagios XI allows users to manage their notification preferences, but if you have custom or advanced schedules from Nagios Core, you can retain those settings. For more details, check out the Understanding Nagios XI Users and Contacts documentation.
[H4] Option 1: Controlling Contact Preferences With Nagios XI
Let users manage notifications in XI by matching the username to the Nagios Core contact and selecting “Create as Monitoring Contact.”
[H4] Option 2: Controlling Contact Preferences Outside Nagios XI
Retain advanced notification settings by matching the username but unchecking the “Create as Monitoring Contact” option to prevent XI from overwriting Core settings.
[H3] 5. Test the XI Server
Make sure you test your new XI server to ensure it is operating effectively. Items you should check include:
• Host and service checks are operating properly and returning the expected results
• Notifications are functioning properly
[H3] 6. De-commission the old Nagios Core Server
Once you have migrated the plugins, scripts, and configuration files from your old Nagios Core installation and have successfully verified Nagios XI’s operation, you may decommission the old Nagios Core server. Before doing so, it is recommended that you retain a backup of the server and its Nagios Core configuration in case you need them in the future.
[H2] Additional Resources
Need help getting started? Here’s a collection of resources to guide you through the switch:
[H3] Important To Know Before Migrating
Understanding The XI Directory Structure
Understanding The Relationship Between XI Users And Core Contacts
[H3] Where To Start
Roadmap for Making the Upgrade From Core to XI
Manual Migration From Core to XI
Automatic Core Migration to XI
[H3] Support
Community Support Forum
CSP Forum
FAQ
[H3] Upgrade Options
Nagios XI For Enterprise
Nagios Enterprise Solutions
[H2] Ready to Start Monitoring?
Join thousands of organizations who trust Nagios for their infrastructure monitoring.
Download Nagios Core
Learn About Nagios XI