TCP Session Setup-Threeway Handshake

A three-way handshake is also known as TCP handshake. It is a method used in TCP/IP network to create a connection between a local host/client and server. It is a three-step method that requires both client and server to exchange SYN and ACK packets before actual data communication begins.

Transmission Control Protocol (TCP) is a connection-oriented, end-to-end reliable protocol. In typical TCP connection, each device maintains its state and the corresponding sequence number to track the incoming sequence of packets. When an end-host device receives a new packet, it will send back and ACK (Acknowledgement) packet, containing an acknowledgement number, which means the device has successfully received the data and is waiting further incoming data as the number indicates.