Tcp/ip state

TCP/IP State Transition Diagram (RFC793)
Gordon McKinney (10 Feb 2004)

starting point CLOSED

A connection progresses through a series of states during its lifetime (listed below). CLOSED isfictional because it represents the state when there is no TCB, and therefore, no connection. Briefly the meanings of the states are:

appl: passive open send:
ap en op ve cti SYN :a pl nd: setimeout send: RST

LISTEN

represents waiting for a connection request from any remote TCP and port. represents waiting for a matching connection request after having sent a connection request.represents waiting for a confirming connection request acknowledgment after having both received and sent a connection request. represents an open connection, data received can be delivered to the user. Thenormal state for the data transfer phase of the connection. represents waiting for a connection termination request from the remote TCP, or an acknowledgment of the connection termination requestpreviously sent. represents waiting for a connection termination request from the remote TCP. represents waiting for a connection termination request from the local user. represents waiting for a connectiontermination request acknowledgment from the remote TCP. represents waiting for an acknowledgment of the connection termination request previously sent to the remote TCP (which includes anacknowledgment of its connection termination request). represents waiting for enough time to pass to be sure the remote TCP received the acknowledgment of its connection termination request. represents noconnection state at all.
FIN_WAIT_1

SYN-SENT

v rec

Y :S

N;

s

d: en

S

, YN

K AC

LISTEN passive open

v rec

:R

ST

ap pl se : se nd nd :S d YN ata

SYN_RCVDSYN-RECEIVED

recv: SYN send: SYN, ACK simultaneous open

SYN_SENT

se

ESTABLISHED

r nd ecv :< :A no CK th in g>
ESTABLISHED data transfer state

CK ,A N CK Y :S :A cv d re sen
recv:...