Examining Advanced Remote OS Detection Methods/Concepts using Perl – This paper discusses the theory and practice behind OS detection with a specific focus on the practice related to the PERL programming language. Methods and concepts for remote operating system detection are closely examined and implemented into Perl code.
You can download it from the following link: https://packetstormsecurity.com/files/download/24280/osdetect-perl.txt
Source: https://packetstormsecurity.com/files/24280/osdetect-perl.txt.html