TCP uses datagram sockets or ports to establish a host-to-host communication. The standard body, called Internet Assigned Numbers Authority (IANA) designates well-known ports to indicate certain services, such as port 80 for HTTP (web) and port 25 for SMTP (mail). The server in the client-server model typically listens on one of these well-known ports in order to receive communication requests from the client. The TCP connection is managed by the operating system by the socket that represents the local endpoint for connection.
The protocol operation consists of a state machine, where the machine needs to keep track of when it is listening for an incoming connection, during the communication session, as ...
