What is the difference between a port number and a protocol number? [closed]

Answer 1

Protocol = how to communicate, Port = where to communicate

Answer 2

ports = ears, mouth, eyeball, touch
protocols = English, Spanish, Sign Language, Braille

Answer 3

A protocol is a specification for how two devices should exchange data in a way that they can both understand. A port is kind of a numbered 'tag' that helps a computer decide who should receive an incoming piece of data.

Many protocols have a port that they run on by default; this makes it easier to discover them or configure applications that use them. But that's not a hard rule; they could always listen on a different port, as long as anyone contacting them knew about the change.

Answer 4

A protocol is an agreement on how to interpret data and how to respond to messages. They generally specify message formats and legal messages. Examples of protocols include:

• TCP/IP
• HTTP
• SSH

A port is part of socket end point in TCP and UDP. They allow the operating system to distinguish which TCP or UDP service on the host should receive incoming messages.

The confusion generally arises because, a number of ports are reserved (eg. port 80) and are generally listened to by severs expecting a particular protocol (HTTP in the case of port 80). While messages send to port 80 are generally expected to be HTTP messages, there is nothing stopping an non-HTTP server from listening on port 80 or an HTTP server from listening on an alternative port (for example 8080 or 8088).

Answer 5

In IP terms, a protocol number is the value assigned to the Layer 4 protocol carried within IP, e.g. 6 for TCP, 17 for UDP, as often found in the /etc/protocols file on most UNIX systems.

A port number is used within the UDP and TCP headers to represent different higher level protocols carried within those protocols, e.g. 25 for SMTP, 80 for HTTP, etc, per /etc/services.

Answer 6

Port = Place where ships come in
Protocol = How the cargo is loaded on the ship