1.SYN - a connection
2.FIN - close the connection
3.ACK - corresponding
4.PSH - urging flag (PSH = 1 TCP packets transmitted immediately created, the receiving end will be submitted directly to the buffer to the application data, without waiting for the buffer area full before delivery)
5.RST - connection reset
6.URG - urgent flag (URG = 1 emergency messages, priority transmission, the receiver priority, the priority return)
