Backtrack 5: Information Gathering: Network Analysis: OS Fingerprinting: xprobe2
The xprobe2 application was built specifically for OS Fingerprinting or being able to accurately guess a servers Operating System. The unfortunate part about xprobe2 is that is extremely outdated and doesn’t even include Windows 7 in its list of OS’s that it can identify. Even though nmap is pretty much the staple for people to use it is still worth discussing xprobe2 because the items it can guess it does a great job at doing so. It may also be possible that you are assessing a network with some really old servers and updated apps don’t include those operating systems anymore so you may get lucky and find the old operating system using xprobe2.