What inspired you to write Nmap, and what were your early expectations? Nmap was mostly written during the summer of 1997, which I spent in Baltimore working as a teaching assistant at Johns Hopkins University. They set me up in a dorm room with Ethernet connectivity, giving me a new network to explore. At the time, I had a directory full of port scanners, such as Strobe for connect scanning, Reflscan for SYN scanning, and the UDP scanner from SATAN. I hacked them all to add options and features, but still found them frustrating to use. So I decided to write my own dream port scanner which would be faster, and support all the scan types and options I wanted.

After months of work and testing, Nmap replaced my other port scanners. At first I kept it to myself, but then I realized that other people might be interested.