Net/IPv4/tcp. c
* Description of states:
*
* Tcp_syn_sent a connection request, waiting for ACK
*
* Tcp_syn_recv received a connection request, sent ACK,
* Waiting for final ack in three-way handshake.
*
* Tcp_established connection established
*
* Tcp_fin_wait1 our side has shutdown, waiting to complete
* Transmission of remaining buffered data
*
* Tcp_fin_wait2 all buffered data sent, waiting for remote
* To Shutdown
*
* Tcp_closing both sides have shutdown but we still have
* Data we have to finish sending
*
* Tcp_time_wait timeout to catch resent junk before entering
* Closed, can only be entered from fin_wait2
* Or closing. required because the other end
* May not have gotten our last ack causing it
* To retransmit the data packet (which we ignore)
*
* Tcp_close_wait remote side has shutdown and is waiting
* Us to finish writing our data and to shutdown
* (We have to close () to move on to last_ack)
*
* Tcp_last_ack out side has shutdown after remote has
* Shutdown. There may still be data in our
* Buffer that we have to finish sending
*
* Tcp_close socket is finished
*/