The Transmission Control Protocol (TCP) is one of the main protocols used on the internet today. If you have opened a web page or have sent an e-mail, you have come across the TCP protocol. The protocol sits at layer 4 of the OSI model, and it is responsible for delivering the data segment between two nodes in a reliable and error-checked manner. The TCP consists of a 128-bit header consists of, among others, source and destination port, sequence number, acknowledgment number, control flags, and checksum: