NSClient++ (nscp)
NSClient++ (nscp) aims to be a simple yet powerful and secure monitoring daemon. It was built for Nagios/Icinga, but nothing in the daemon is Nagios/Icinga specific and it can be used in many other scenarios where you want to receive/distribute check metrics.
The daemon has 3 main functions:
- Allow a remote machine (monitoring server) to request commands to be run on this machine (the monitored machine) which return the status of the machine.
- Submit the same results to a remote (monitoring server).
- Take action and perform tasks.
NSClient++ can be found at: http://nsclient.org
Documentation can be found at: http://docs.nsclient.org
Extending NSClient++
NSClient++ is designed to be open ended and allow you to customize it in any way you design thus extensibility is a core feature.
- ExternalScripts responds to queries and are executed by the operating system and the results are returned as-is. This is generally the simplest way to extend NSClient++ as you can utilize whatever infrastructure or skill set you already have.
- LuaScripts are internal scripts which runs inside NSClient++ and performs various tasks and/or responds to queries. This is the best option if you want to allow the script to run on any platform with as little infrastructure as possible.
- PythonScripts are internal scripts which runs inside NSClient++ and performs various tasks and/or responds to queries. Python is an easy and powerful language but it requires you to also install python which is often not possible on server hardware.
- .Net modules similar to Native modules below but written on the dot-net platform. This allows you to write components on top of the large dot-net ecosystem.
- Modules are native plugins which can extend NSClient++ in pretty much any way possible. This is probably the most complicated way but gives you the most power and control.
Talking to NSClient++
Since NSClient++ is meaningless by itself it also supports a lot of protocols to allow it to be used by a lot of monitoring solutions.
- NRPE (Nagios Remote plugin Executor) is a Nagios centric protocol to collect remote metrics.
- NSCA (Nagios Service Check Acceptor) is a Nagios centric protocol for submitting results.
- NSCP is the native NSClient++ protocol (still under development)
- dNSCP is a high performance distributed version of NSCP for high volume traffic.
- NRDP is a replacement for NSCA.
- check_mk is a protocol utilized by the check_mk monitoring system.
- Syslog is a protocol primarily designed for submitting log records.
- Graphite allows you do real-time graphing.
- SMTP is more of a toy currently.
Supported OS/Platform
NSClient++ should run on the following operating systems:
- Windows: In theory from Windows XP with lots of service back (verified Windows 2008 R2 and later)
- Linux: Debian, Centos and Ubuntu (and possibly others as well)
Which package to download
The following packages are produced by the official build pipelines. Pick the one that matches your operating system and architecture:
| Operating system | Version | Architecture | Package / artifact name | Notes |
|---|---|---|---|---|
| Windows (modern) | Windows 10 / 11, Server 2016 / 2019 / 2022 / 2025 | x64 (64-bit) | NSCP--x64.msi |
Recommended for all modern Windows systems. Built with MSVC 2022. |
| Windows (modern) | Windows 10 / 11, Server 2016 / 2019 / 2022 / 2025 | x86 (32-bit) | NSCP--Win32.msi |
Use only on 32-bit Windows installations. Built with MSVC 2022. |
| Windows (modern) | Windows 11 ARM, Server 2025 ARM | ARM64 | NSCP--ARM64.msi |
Native ARM64 build, cross-compiled with the v143 toolset. Use this on Windows-on-ARM devices (e.g. Surface Pro X / Copilot+ PCs, ARM-based Azure VMs). |
| Windows (legacy) | Windows XP and above | x86 (32-bit) | NSCP--Win32-legacy-xp.msi |
Statically linked, built with the v141_xp toolset. Use this on any Windows older than Windows 10 / Server 2016. Works on x64 versions of these older OSes too. |
| Ubuntu | 24.04 LTS (Noble) | x64 (amd64) | NSCP--ubuntu-24.04-amd64.deb |
Should also install on recent Debian/Ubuntu derivatives with compatible glibc and Lua 5.4. |
| Ubuntu | 24.04 LTS (Noble) | ARM64 (aarch64) | NSCP--ubuntu-24.04-arm64.deb |
For 64-bit ARM hosts (e.g. AWS Graviton, Ampere Altra, Raspberry Pi 4/5 running Ubuntu 24.04 arm64). |
| Rocky Linux / RHEL / AlmaLinux | 9 | x64 (x86_64) | NSCP--rocky-9-x86_64.rpm |
Compatible with RHEL 9 and other RHEL 9 rebuilds (AlmaLinux 9, Oracle Linux 9, CentOS Stream 9). |
| Rocky Linux / RHEL / AlmaLinux | 9 | ARM64 (aarch64) | NSCP--rocky-9-aarch64.rpm |
64-bit ARM build for RHEL 9-family distributions. |
| Rocky Linux / RHEL / AlmaLinux | 10 | x64 (x86_64) | NSCP--rocky-10-x86_64.rpm |
Compatible with RHEL 10 and other RHEL 10 rebuilds. |
| Rocky Linux / RHEL / AlmaLinux | 10 | ARM64 (aarch64) | NSCP--rocky-10-aarch64.rpm |
64-bit ARM build for RHEL 10-family distributions. |
In addition, a stand-alone check_nsclient binary is published alongside each Linux package for use as a Nagios/Icinga check plugin.
> Note: On unsupported distributions you can build from source — see build.md.
Building NSClient++
NSClient++ is built using CMake and Visual Studio 2022. You can find detailed instructions for building locally in the build.md file.
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