Xprobe2 is a fuzzy remote OS fingerprinting tool with functionality that is heavily based on Xprobe, but also uses other OS fingerprinting techniques.
You can download it from the following link: https://packetstormsecurity.com/files/download/31534/xprobe2-0.2rc1.tar.gz
Source: https://packetstormsecurity.com/files/31534/xprobe2-0.2rc1.tar.gz.html