Once a service is running on a certain port, you can't run other services on it. Developers use file transfer protocols (FTPs) or SSH to run encrypted tunnels across computers to share information between hosts. Services that rely on the Internet (like web browsers, web pages, and file transfer services) rely on specific ports to receive and transmit information. Every IP address contains two kinds of ports, UDP and TCP ports, and there are up to 65,535 of each for any given IP address.
All communication over the Internet is exchanged via ports. Ports are an integral part of the Internet's communication model. In contrast, a port that rejects connections or ignores all packets is a closed port. In cybersecurity, the term open port refers to a TCP or UDP port number that is configured to accept packets.
