malicious hackers on the server

[Festus1965]

date: 25.04.2018

time: about 11:30 Thailand UTC+7

server Ubuntu, minetestserver 0.4.16

What happened:

A normal well known gamer joined and started bad language via chat, ingame mail ...

I needed some of his new joins with several names, to separate his IPs from the ones the normal user has.
So there was Germany (real and ok) and then new India (the bad one 137.97.89.x)

However, "it" got into that normal login, and changes several things:
* admin password didn't work anymore
* normal gamers accounts works, just was back, but her iron door doesn't open on her own will
* not found ...

stopped server,
reactivated old admin account via other player
separated the good and the bad IPs and used nicks in the xban file, to clear up, and ban
and closed firewall for IPs from 137.97.89.x

So far, someone similar story ?