ignore my ignorace, I don't know the correct name:
when a tcp/ip stack receives a connection request, which is not assigned
(no server listening on it), it sends a SYN (correct??) so that the other
host will get a "connection refused".
as of at least 1.3.63, this mechanism seems not to be working anymore,
e.g. "telnet localhost 4444" (4444=not bound) ends with a timeout.
note that this also happens with non-local (not loopback) connections.
regards, herp