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I use Zip Bombs to Protect my Server
(idiallo.com)
This is a most excellent place for technology news and articles.
For research purposes you could make it password protected, which would make it legal, though. Like i said having one is a gray area, because the law is made extremly vague. Like i said i dont know of any judgements about it, but it is still a possibility. If you life in germany and are inclined for an archive bomb and care about your legal safety contact a lawyer beforehand