Service Banner Fingerprinting in C – This paper is a supplement to modular’s tcpscan series. It covers how to write C programs that will perform banner fingerprinting using various standard servers as examples.
You can download it from the following link: https://packetstormsecurity.com/files/download/30981/sbfprint.txt
Source: https://packetstormsecurity.com/files/30981/sbfprint.txt.html