The Siphon Project is designed to be a portable passive network mapping suite. Siphon currently does passive mapping of TCP ports and passive OS identification.
You can download it from the following link: https://packetstormsecurity.com/files/download/17783/siphon-v.666.tar.gz
Source: https://packetstormsecurity.com/files/17783/siphon-v.666.tar.gz.html