TCP header flags

PUSH flag: When you type "ls\n", client want to send package immediately even only has three bytes data. this flag help you to do that

SYN flag, ACK flag: for tcp 3 way handshake.
SYN->
               <-SYN ACK
SYN->

FIN flag, ACK flag: for tcp termination
FIN->
              <-not FIN ACK
              <- FIN ACK
ACK->