This OS fingerprinting probe tests to determine if the remote host echoes
						back the IP 'ID' value from the probe packet. An attacker sends a UDP
						datagram with an arbitrary IP 'ID' value to a closed port on the remote host
						to observe the manner in which this bit is echoed back in the ICMP error
						message. The identification field (ID) is typically utilized for
						reassembling a fragmented packet. Some operating systems or router firmware
						reverse the bit order of the ID field when echoing the IP Header portion of
						the original datagram within an ICMP error message.