Question about licencing (GPL with closed source modules)

[TheDushan]

Hello

My name is Du?an and I author of OpenWolf (OWEngine - GitHub link) video game engine what is based on idTech3 technology.
I would like to have new anti-cheat module what I would like to link dynamically into my game engine.
For oblivious reasons I would like to keep that part of source closed, and because of that my questions have more legal character because my entire code is released under GPL v2/v3.

My question is this, am I allowed to keep that part (anti-cheat module) into closed source and to distribute it dynamically with rest of binary files?

Thanks

[Svartalf]

Pure and simple, NO. If it's linked against a GPL binary, you have to give it *ALL* out or be in license non-compliance. You don't want to face off against ZeniMax on that one.

[Svartalf]

(Now, if you can convince them and all the other rights holders that've contributed to the core to sign off on a proprietary license there, yeah...but...best of luck on THAT. >;-D)

[TheDushan]

Thanks for reply
ye, I thought that, but it doesn't harm anyone if I ask for the second opinion

[Svartalf]

Thanks for reply
ye, I thought that, but it doesn't harm anyone if I ask for the second opinion

Nary a problem there- and you'd be right on that score.

[CapsAdmin]

Can you explain why you'd need an anti cheat in the first place? There might be other solutions to what you want to do.

I don't see how it can violate GPL if developed externally as an addon to your engine though. For example there exists proprietary software on Linux.

[Svartalf]

Can you explain why you'd need an anti cheat in the first place? There might be other solutions to what you want to do.

I don't see how it can violate GPL if developed externally as an addon to your engine though. For example there exists proprietary software on Linux.

Depends on how it's integrated. Standalone app? No violation. Linked in a' la plugin, violates the license four ways from Sunday (Magic word, "linked in"- you can't dlopen the thing, etc. If you can find a way to RPC the whole thing (which then can be circumvented...heh...) then you've no problems...)

Just because it's externally developed does **NOT** make it magically proof against GPL requirements.

[smalltalker]

If we only rely on the text of GPLv2, the only thing you can't do is distribute a derivative work of the licensed code without giving the source for the derivative work too. Linking is relevant only in the sense that affects distribution. For example, if you download a GPL piece of software, being it a library, an engine, or a full program, and then dynamically link or statically link it with code that is not a derivative work of the downloaded GPLd code, then no clause in the GPL was broken and that is perfectly legal.
So the main question here is: Is your anti-cheat code a derivative work of the game engine? If it is, then you can't distribute it without source code regardless the linking mechanism.
A workaround could be making your anti-cheat module work to an API you define which is not related to your game engine. Then do at least two plugins: one that adapts that API to your game engine and other that adapts your API to an unrelated game engine, like Unreal or something like that. Then make those two plugin adapters public domain. Now your anti cheat module is completely unrelated to your game engine, so it can't possibly be a derivative work. You are free to distribute it as you please, i.e., closed source.