Half close, Half open, Reset
Possible for one end to close while the other end sends data. Used in “rsh” command. Fig 18.10, 18.11
Half-open: one side crashed and lost memory of connection while other side thinks connection is open. Usually connection is reset upon communication.
Reset => used to abort connection. Queued data (if any) is dumped.
Orderly release => FIN sent after queued data transmitted.