An attacker engages in ICMP stack fingerprinting techniques to determine
						the operating system type and version of a remote target. The role of ICMP
						as an ubiquitous diagnostic messaging protocol means that ICMP
						fingerprinting techniques are applicable to almost any internet host in a
						similar manner as TCP. ICMP fingerprinting techniques involve the generation
						of ICMP messages and analyzing the responses. This method is limited in that
						most firewalls are configured to block ICMP messages for security reasons,
						so it is most effective when used on an internal network segment. OS
						fingerprints using ICMP usually involve multiple different probes as the
						information returned from any one probe is usually insufficient to support a
						reliable OS inference.