David Fifield has been working with GNU/Linux and free software for about 10 years. He has a degree in mathematics and computer science from the Metropolitan State College of Denver. He lives in Denver, Colorado, USA. David has worked full-time on the Nmap security scanner and its associated tools for about two years. He wrote the Ndiff scan comparison utility and has been active in the maintenance and enhancement of the Ncat network tool and the Zenmap GUI, as well as certain subsystems of Nmap such as the scripting engine. Much of his time has been spent improving Nmap's performance and accuracy.