TCP closure process (fourth wave):
The ESTABLISHED : The current state of a connection
CLOSE_WAIT : the Server-Client receives FIN packet from the terminal, sends an ACK back to the Client-side into CLOSE_WAIT state.
LAST_ACK : Server-side at the same time inform the upper application client to close the message, send a FIN packet back to the Client side, and then enter LAST_ACK stage, wait for the client ACK.
CLOSED : the Client-Server receives the Ack end, into the CLOSED state, the connection is closed.
FIN_WAIT1 : Client sends FIN packet, and then enters FIN_WAIT1 state, waiting for the end Server ACK.
FIN_WAIT2 : the Client-Server receives the ACK terminal, enter FIN_WAIT2 state, waiting for the end Server FIN packet.
TIME_WAIT : the Client-Server receives the FIN terminal, sends an ACK back to the Server side, and then enters the TIME_WAIT state, waiting (2 * MSL) Server ACK after receiving end, TCP connection is closed.
Examples of monitoring:
