Gordon Lyon is a popular, successful and charismatic open-source software maker. Right now, he's not a happy man.
You probably know him better by his nickname, Fyodor (after Fyodor Dostoyevsky, author of Notes From Undergound). He is the creator and maintainer of the widely-used network auditing and penetration-testing tool Nmap.
You probably know Nmap. If you've ever done any network troubleshooting or security assessment, you've probably used it. It can help you locate rogue PCs and servers, spot services which shouldn't be running, identify firewalls and routers on your network, and much more.