Fyodor (Gordon Lyon) and Nmap
termsecuritynetworking
The author of Nmap, published in Phrack in 1997 and still the standard port scanner and host-discovery tool - the program that taught the industry what its own networks actually expose.
Nmap's contribution goes beyond scanning: OS fingerprinting by TCP/IP stack quirks, service and version detection, and a scripting engine that turned it into a small vulnerability scanner. It is also a rare piece of security software with cultural reach - it appears on screen in The Matrix Reloaded, which Fyodor documents proudly on the project's Movies page. He also maintains the seclists archives, where much of the field's public discussion has been preserved for decades.
Also known as: gordon lyon, nmap, insecure.org, network mapper