Can I use the Nagios Plugins in my own project?

Firstly, there is a distinction between a Nagios plugin and plugins from the Nagios Plugins project.

Although Nagios (the system) is licenced under the GPL, plugins are executed in their own environment so does not fall under the viral aspect of the GPL. Therefore, any plugin written for use by Nagios can be under any licence the copyright holder selects.

However, the plugins contained within the Nagios Plugins project are distributed under the GPL. If you distribute an application that includes the Nagios Plugins (modified or not), you are required to distribute a copy of the source code for the plugins under the terms of the GPL, regardless of the licensing for the rest of the application.

If you write a plugin which is a derivative work from code of the Nagios Plugins project, then your plugin must also be licenced under the GPL, although you own thecopyright for your modified portions.

Derivative work usually includes:

• modified versions of the plugins
• other software that contains code (modified or not) copied from the plugins
• other software that #includes header files from the plugins
• other software that has linked against library files from the plugins

and does not usually include:

• other software that parses the output of a plugin run from the cmdline, exit status, etc
• software that provides a "wrapper" for cmdline execution of the plugin
• software that uses status codes and other values which are in the header files, but also described in the documentation (though not including or linking to the source)