TCP State Machine (TCP/IP Illustrated vol. 1) W. Richard Stevens

CLOSED

LISTEN

SYN_SENT

SYN_RCVD

ESTABLISHED

CLOSE_WAIT

LAST_ACK

CLOSING

FIN_WAIT_1

TIME_WAIT

FIN_WAIT_2

Starting point

Appl: passive open

send: <nothing.

Appl: active open

send: SYN

Appl: close

Or timeout

App: send data

Send:SYN

Recv:RST

Recv:SYN; send:SYN-ACK

Recv: SYN; send:SYN-ACK

simultaneous open

Recv:ACK; send:<nothing.

Recv:SYN,ACK

Send:ACK

Data transfer state

Appl : close

Send:

FIN

passive close

Recv:ACK

Send:

nothing

Appl:

close

Close:

FIN

Appl: close

Send:FIN

Recv:FIN

send: ACK

Recv:FIN,ACK;

send:ACK

Recv:FIN

send:ACK

Recv: ACK

send:

<nothing>

Recv: ACK

send: nothing

Simultaneous close

2MSL timeout

Active close

Client transitions

Server transitions

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