Showing posts from August, 2020

Data transmission over TCP

Data transmission over TCPIn the first article we discussed how the TCP connection initiation and termination is performed and how we can see this in Wireshark. In this article, we will discuss the actual TCP data transmission procedure.TCP analysis articlesTCP connection establishment and terminationData transmission over TCPThe happy scenarioTCP is using the cumulative acknowledgement approach, in which the TCP receiver is normally sending an ACK that represents the amount of contiguous data it got. The procedure of TCP transmission is as followsAt the connection start, each side of the connection picks some random number called initial sequence number ISN. This number represents the number of the first byte this side will send to the other side. To make analysis easier, Wireshark will show this field starting from 0 but you can get the actual sequence number from the raw sequence number field on the Wireshark expert view.For each byte sent, the transmitting side will increase the s…