As far as I know, breaking the law online in Germany (such as sharing copyrighted content) often results in a fine from a private law firm which gets your personal data from your provider by sending them some sort of "cease and desist" letter mentioning the violation. I understand that this process doesn't involve an actual lawsuit. I wonder what kind of proof of the client's wrong-doing is actually required for the ISP to disclose their personal data.
For instance, I have an open SSH port in my home network, and there are regular attempts to login using default usernames/passwords, which AFAIK is just as illegal as sharing copyrighted files. If I see a German IP in the logs, what kind of proof do I have to send to the ISP in order to get the offender's identity from them?