Some of you have not completed Networking module yet, and thus may not familiar with the role of port numbers in a client-server connection and communication. A service offered by a server can be accessed via some predefined port number. For instance, consider a SMTP email server, which listens to port number 25. If a client wants to communicate with the server for a SMTP communication, the client sends packets to the server’s IP address at port number 25. The server responses by sending packets to the client’s IP address at another port number selected by the client, which is greater than …