control flag field
The control flag field is a data field in the TCP header that follows the header length data field.
The control flag field contains six bit indicators that control the connection state, i.e. connection establishment, connection maintenance and connection termination. In addition, the flags handle the processing of data and their urgencies.
The Control flag field includes six flags: Urgent flag( URG), Acknowledge flag( ACK), Push flag( PSH), Reset flag ( RST), Synchronization flag ( SYN) and Final flag ( FIN).