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What does last ACK mean?
LAST_ACK means your end has received a FIN from the peer, sent an ACK, sent a FIN, and is waiting for the final ACK from the peer. At this point there is nothing further the application can do: the socket is closed.
Why is ACK needed?
The ACK allows the receiver to “slide the window,” allowing the sender to send more data. Without the ACK, TCP/IP will not send more unacknowledged data than the window size allows.
How do TCP sessions work?
The TCP session is sending packets as fast as possible, so when the client sends the FIN and closes its part, the server is still sending lots of data for a moment. In this case, the client sends RST packets until the server stops sending data.
What does FIN_WAIT_2 mean?
FIN_WAIT_2 seems to occur when the server has an active connection with a client and wants to shut down the TCP connection (probably in response to a normal application layer “exit”). The server sends the client a packet with a “FIN” bit set. When the server gets that packet, it goes into FIN_WAIT_2 state.
Why is the last ack needed In TCP four way?
It seems only if the scenario described above happens reasonably frequently, will the last ACK (4) have a significant impact. The ACK to a FIN is required because the end sending the FIN will retransmit it until it receives an ACK.
How does the termination of a TCP connection work?
The common way of terminating a TCP connection is by using the TCP header’s FIN flag. This mechanism allows each host to release its own side of the connection individually. How mechanism works In TCP : Suppose that the client application decides it wants to close the connection. (Note that the server could also choose to close the connection).
What’s the difference between fin, RST and ack in TCP?
For example, a TCP end receives a packet for which there is no connection. The receiving side will send a TCP RST to the remote, to close the connection and again set up if required. The other ends send the TCP RST Ack. In contrast to the FIN, RST, and RST Ack closes the connection in both directions immediately.
When to use abrupt connection release in TCP?
In Abrupt connection release, either one TCP entity is forced to close the connection or one user closes both directions of data transfer. An abrupt connection release is carried out when a RST segment is sent.