TCP

The Transmission Control Protocol provides reliable, connection-oriented communication using features like error checking, flow control, and validation. It is used in applications requiring data integrity, like web browsing, emails, and file transfers.

It uses a method called Three-way Handshake to establish a connection between devices. It works as follows:

• A request is sent with a bit named SYN (Synchronize) to make the first contact with the server

• If SYN is sent to a closed port, the target server will respond with a TCP packet called RST (Reset), which is returned to the client, and the connection will be rejected

• If it reaches an open port, the server will then respond with a packet containing the SYN bit, as well as another bit, called the ACK (Acknowledgment)

• The initial device will send a packet that contains the ACK bit by itself, confirming that the connection has been set up successfully

• Then, the connection can be established using TCP