Back in the day, I wrote a tool which used to display server list with active players and their scores so you could hop on a server when you see a friend is on. This was before steam existed (no such feature was available at the time).

While writing this tool, I sent a bad packet to a server I was testing with, and the server went down. I still have the source code (wrote it in delphi), I wonder if this thing can still crash servers, given that decade-old bugs exist :D