Zetetic combines knowledge of various application protocols with probabilistic
automata to perform protocol analysis independent of "well-known port numbers."
Given a stream (and, optionally, lower-level information), it will calculate a
vector of real numbers between 0 and 1 (inclusive), indicating conformance to
various protocols. For many protocols, the first few datagrams exchanged will
suffice for clear determination of session protocol. Zetetic examines both sides
of a session, and can determine protocol mismatches (attempts to speak, for
example, SMTP to an HTTP server).