Anyone who has dissected a packet off a network should be familiar with the concept of operating system fingerprinting. Essentially, operating systems have little nuances in how they construct packets to send over the network. These nuances are useful as signatures, giving us a good idea of the operating system that sent the packet. We're preparing to spoof the stack of a chosen OS as previously explained, so let's cover a tool in Kali that will come in handy for a variety of recon situations: Passive Operating system Fingerprinter (p0f).
Its power is in its simplicity: it watches for packets, matches signatures according to a signature database of known systems, and gives you the results. Of course, ...
