what is port & port number?

Answer 1

All the computers in the world have a unique public I.P address . Therefore suppose my computer wants to communicate with yours , i can always do it via the I.P address.

However you will be using some program or a software for the communication. Now the software on my comp sends a message to your comp saying

"Hi my I.P is 192.168.123.26" and i want to talk to u via port 80. This means that a special socket or a number is assigned to that specific communication. Now the software on your comp may reply. "Sorry i have port 80 open for some other application. "

These lead to a lot of confusion at first and ultimately lead to the standardisation of port numbers. This means that standard software always use a definite port number.

Thus port number is nothing but a software entity which provides a special means of communication over the network.

As i already mentioned all the public I.P address are unique. Hence we can conclude that there will be only one entity which sends out or receives msg through an I.P address + port combination.

That is to say my comp 192.168.123.26:80 is a unique entity in the whole world.

Answer 2

Where port numbers are concerned, consider an analogy between the computer and the telephone. Port numbers and their associated network addresses work something like telephone numbers and associated extensions...

One can think of a network address - say, an IP address - like a telephone number. The IP address gives a unique number for reaching someone on the Internet, just as a telephone number allows you to reach a specific destination on the public telephone network.

(Note that telephone numbers have additional features that IP addresses do not have, such as area codes that provide some geographic information about a location.)

Many larger organizations set up their telephone networks to use phone extensions. These extensions are typically 2-5 digit numbers that identify an individual phone within the organization. But from the outside, all of these extensions are associated with a single telephone number (in the USA, often a 1-800 or 1-888 number).

A network port number functions similarly to a telephone extension. Taken together with a network address, a port number identifies both a computer and also a "channel" within that computer where network communication will take place. Just as different organizations may use the same extension numbers "inside" their primary phone number, different computers use the same set of port numbers.

Answer 3

Port is a virtual entity that is used in communication over a network. It lies at the Transport layer in the nertwork protocol stack and is used to establish end to end communication. All the applications running at the application layer use a port number at transport layer to communicate with another application at other end.A port number plus IP address form what is called a socket. It can be taken as a pipe for communication over a network.A port is identified by a port number and it is always unique. Port numbers upto 1024 are well known ports and are used for some well known applications.
eg. Telnet has a port number 23.

Answer 4

When two computers need to talk to each other, they have to decide how they will communicate. A port is simple a place in memory that will be used to send and receive messages between the two computers. As it has to be identified somehow, it is assigned a number. Two computers can decide to use any port or port number to communicate.

But to make it easier to write software, it was agreed years ago that certain ports (port numbers) would be used for specific functions. For example, port 80 could be used for e-mail. By agreeing that all e-mail will come in marked with the number "80", it is easy to determine e-mail traffic, direct it to the proper servers, filter it, or block it if desired.

If you are asking about information for a specific port, or what port to use for a specific application, or something, you will need to edit with more detail....

Answer 5

when a client want to receive any data(http) or any file(ftp) means it first request server.the server then send a responce to client in which it specify the port number through that only that particular client can listen for the server respouce.if the server do not specify it means the client take any one anonemous port ie.port 0.
for each portocol there is some specific port number.based on that the server select the port.

Answer 6

Port is the place where data would arive n leave the network. iEach port is identified with a unique port no. The data packets will have the IP address n the port no to reach it's destination.

Answer 7

1.A port is an interface on a computer to which you can connect a device.
2.A port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server.