TCP - State

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Process - LifeCycle (Entity State) (Status) in TCP.

During the lifetime of a TCP connection the local end-point undergoes a series of state changes.

Management

Visualization

List

State names vary with UNIX dialects, so it's not possible to provide a complete list. Some common TCP state names are: CLOSED, IDLE, BOUND, LISTEN, ESTABLISHED, SYN_SENT, SYN_RCDV, ESTABLISHED, CLOSE_WAIT, FIN_WAIT1, CLOSING, LAST_ACK, FIN_WAIT_2, and TIME_WAIT.

Rfc 793 Description:

State Description
CLOSE WAIT represents waiting for a connection termination request from the local user.
CLOSED represents no connection state at all.
CLOSING represents waiting for a connection termination request acknowledgment from the remote TCP.
ESTAB represents an open connection, data received can be delivered to the user. The normal state for the data transfer phase of the connection.
FINWAIT-1 represents waiting for a connection termination request from the remote TCP, or an acknowledgment of the connection termination request previously sent.
FINWAIT-2 represents waiting for a connection termination request from the remote TCP.
LAST-ACK represents waiting for an acknowledgment of the connection termination request previously sent to the remote TCP (which includes an acknowledgment of its connection termination request).
LISTEN represents waiting for a connection request from any remote TCP and port.
SYN RCVD represents waiting for a confirming connection request acknowledgment after having both received and sent a connection request.
SYN SENT represents waiting for a matching connection request after having sent a connection request.
TIME WAIT represents waiting for enough time to pass to be sure the remote TCP received the acknowledgment of its connection termination request.

Documentation / Reference


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