Tcp状态变迁详解

   A connection progresses through a series of states during its  lifetime.  The states are:  LISTEN, SYN-SENT, SYN-RECEIVED,
  ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK,  TIME-WAIT, and the fictional state CLOSED.  CLOSED is fictional
  because it represents the state when there is no TCB, and therefore,  no connection.  Briefly the meanings of the states are:
    LISTEN - represents waiting for a connection request from any remote    TCP and port.
    SYN-SENT - represents waiting for a matching connection request    after having sent a connection request.
    SYN-RECEIVED - represents waiting for a confirming connection    request acknowledgment after having both received and sent a    connection request.
    ESTABLISHED - represents an open connection, data received can be    delivered to the user.  The normal state for the data transfer phase    of the connection.
    FIN-WAIT-1 - represents waiting for a connection termination request    from the remote TCP, or an acknowledgment of the connection    termination request previously sent.
    FIN-WAIT-2 - represents waiting for a connection termination request    from the remote TCP.
    CLOSE-WAIT - represents waiting for a connection termination request    from the local user.
    CLOSING - represents waiting for a connection termination request    acknowledgment from the remote TCP.
    LAST-ACK - represents waiting for an acknowledgment of the
    connection termination request previously sent to the remote TCP    (which includes an acknowledgment of its connection termination    request).
未完待续