It has its own location and is stationary. A socket does not have a number and moves around, connecting computers and then severing when the connection is finished. A port is only capable of listening, while the socket is able to make both computers hear each other. Another difference between a socket and a port is that a socket is only software related, while a port has both a software and hardware definition. On the hardware side, a port is used to connect other devices to the computer.
When a user connects a mouse to his or her computer, a wire is docked into a port, and the electronic connection is established. These ports are called the well-known ports. Higher-numbered ports are available for general use by applications and are known as ephemeral ports.
It is used to identify both a machine and a service within the machine. The same port number can be used in different computer running on same software. Attention reader! Previous Difference between Physical and Logical Topology.
Recommended Articles. Yes you can filter incoming traffic on port, ip address and protocol even on basic firewalls. Restricting ports is for security reasons Rgds Steve. I want to read a data from a machine which supports open protocol if the machine is in network and if I know IP address and port number socket how can I read a data from it I know it send and receive data in packet format. Thank you, Steve! Hi Not quite sure of what you mean exactly but load balancing is quite common.
Question: When a program on your computer sends or receives data over the Internet it sends that data to an ip address and a specific port on the remote computer. How does my computer know what port a specific application is working on another computer to populate the TCP Header? When Machine A connects to machine B. The source ip and port are contained in the connection packet as well as the destination port and IP address. Hi You need to use DNS. Most devices have MDNS enabled. Great site.
I have a quick question. And it must also include its own IP address and port number. But it is not required to include its own IP address and port number. TCP is a connection orientated protocol and so the destination device needs to know who to send a reply to. Can Server and client share the port number, eg : Server is listening at port num : and client also listens on the same port num : Yes providing they are on different hardware.
Machines use 16bits for the port numbers hence the limitation of 64, Good job Steve. I have a question, and it goes like this: if i have 2 browsers from my PC connecting to the same service, for example both browsers are connecting to google.
Meaning can more than one socket connect to a socket at the same time? Yes they use the same IP and port on the Google server but different ports on the client.
Hi, Thanks for this information sharing. It is very well explained. I have following doubt, What I understand is TCP protocol takes care of data transmission error that duplication of packets or packet in true form delivered to other end. This is not done in UDP protocol. Could you please clear my doubt. Answer will help me alot. Google and Yaoo have different IP addresses. Does that make sense? The IP address of google and yahoo is different.
The port number 80 is the open port of server. If I want to connect Google server,I will open a new port,for example I will open port , at the same time I will open another port to connect with Yahoo server.
I have few doubts though, hope you can clear them: 1. Can you tell if a server uses a single port 80 on all of its connections to clients? Or is it used only by the Welcoming socket? Can port 80 handle multiple connections simultaneously? A port e. The last six lines of the output contain two examples of the fact that address and port are not enough to uniquely identify a socket.
There are two distinct connections between I think Hagrawal's misunderstanding arises from my very careful use of the word "identifies". I mean "completely, unambiguously and uniquely identifies". If all you have is address and port, you don't have enough information to tell these sockets apart.
It's not enough information to identify a socket. A connection is fully specified by the pair of sockets at the ends. A local socket may participate in many connections to different foreign sockets. This definition of socket is not helpful from a programming perspective because it is not the same as a socket object , which is the endpoint of a particular connection. To a programmer, and most of this question's audience are programmers, this is a vital functional difference.
The fundamental problem is that the TCP RFC definition of socket is in conflict with the defintion of socket used by all major operating systems and libraries.
By definition the RFC is correct. When a library misuses terminology, this does not supersede the RFC. Instead, it imposes a burden of responsibility on users of that library to understand both interpretations and to be careful with words and context.
Winett, Lincoln Laboratory. A port is a number between 1 and inclusive that signifies a logical gate in a device. Every connection between a client and server requires a unique socket. A socket represents a single connection between two network applications. These two applications nominally run on different computers, but sockets can also be used for interprocess communication on a single computer.
Applications can create multiple sockets for communicating with each other. Sockets are bidirectional, meaning that either side of the connection is capable of both sending and receiving data. Therefore a socket can be created theoretically at any level of the OSI model from 2 upwards. Programmers often use sockets in network programming, albeit indirectly.
Programming libraries like Winsock hide many of the low-level details of socket programming. Sockets have been in widespread use since the early s. A port represents an endpoint or "channel" for network communications.
Port numbers allow different applications on the same computer to utilize network resources without interfering with each other. Port numbers most commonly appear in network programming, particularly socket programming. Sometimes, though, port numbers are made visible to the casual user.
Normally, a Web site uses port number 80 and this number need not be included with the URL although it can be. In IP networking, port numbers can theoretically range from 0 to Most popular network applications, though, use port numbers at the low end of the range such as 80 for HTTP. Note: The term port also refers to several other aspects of network technology. A port can refer to a physical connection point for peripheral devices such as serial, parallel, and USB ports.
The term port also refers to certain Ethernet connection points, such as those on a hub, switch, or router. Although a lot technical stuff is already given above for sockets I would like to add my answer, just in case , if somebody still could not feel the difference between ip, port and sockets.
Firsty, I think we should start with a little understanding of what constitutes getting a packet from A to B. A common definition for a network is the use of the OSI Model which separates a network out into a number of layers according to purpose.
There are a few important ones, which we'll cover here:. TCP contains, amongst other things, the concept of ports. As it happens, so too does UDP , and other transport layer protocols. They don't technically need to feature ports, but these ports do provide a way for multiple applications in the layers above to use the same computer to receive and indeed make outgoing connections.
Each features a source port and address, and a target port and address. This is so that in any given session, the target application can respond, as well as receive, from the source.
So ports are essentially a specification-mandated way of allowing multiple concurrent connections sharing the same address. Now, we need to take a look at how you communicate from an application point of view to the outside world. To do this, you need to kindly ask your operating system and since most OSes support the Berkeley Sockets way of doing things, we see we can create sockets involving ports from an application like this:.
So in the sockaddr structures, we'll specify our port and bam! Job done! Well, almost, except:. So really a port is a subset of the requirements for forming an internet socket. Unfortunately, it just so happens that the meaning of the word socket has been applied to several different ideas.
So I heartily advise you name your next project socket, just to add to the confusion ;. Did I just flunk network ? Generally, you will get a lot of theoretical but one of the easiest ways to differentiate these two concepts is as follows:. In order to get a service, you need a service number. This service number is called a port. Simple as that. Now, many people can request the service and a connection from client-server has established.
There will be a lot of connections. Each connection represent a client. In order to maintain each connection, the server creates a socket per connection to maintain its client. There seems to be a lot of answers equating socket with the connection between 2 PC's.. The important part is that it's addressable and active. Sending a message to 1. IPX socket numbers are equivalent to IP ports.
But, they all offer a unique addressable endpoint. Since IP has become the dominant protocol, a port in networking terms has become synonomous with either a UDP or TCP port number - which is a portion of the socket address. UDP is connection-less - meaning no virtual circuit between the 2 endpoints is ever created. However, we still refer to UDP sockets as the endpoint. This makes it possible to have other protocols eg. These are basic networking concepts so I will explain them in an easy yet a comprehensive way to understand in details.
A port can be described as an internal address within a host that identifies a program or process. A socket can be described as a programming interface allowing a program to communicate with other programs or processes, on the internet, or locally. A 'socket' is made in code by taking a port and a hostname or network adapter and combining them into a data structure that you can use to send or receive data.
After reading the excellent up-voted answers, I found that the following point needed emphasis for me, a newcomer to network programming:. TCP-IP connections are bi-directional pathways connecting one address:port combination with another address:port combination. Therefore, whenever you open a connection from your local machine to a port on a remote server say www. It can be helpful to use netstat to look at your machine's connections:. A socket is a special type of file handle which is used by a process to request network services from the operating system.
A conversation is the communication link between two processes thus depicting an association between two. The half-association is also called a socket or a transport address.
That is, a socket is an end point for communication that can be named and addressed in a network. The socket interface is one of several application programming interfaces APIs to the communication protocols. Designed to be a generic communication programming interface, it was first introduced by the 4. Although it has not been standardized, it has become a de facto industry standard. A socket is a communication endpoint.
The C socket API expects you to first get a blank socket object from the system that you can then either bind to a local socket address to directly retrieve incoming traffic for connection-less protocols or to accept incoming connection requests for connection-oriented protocols or that you can connect to a remote socket address for either kind of protocol.
You can even do both if you want to control both, the local socket address a socket is bound to and the remote socket address a socket is connected to. For connection-less protocols connecting a socket is even optional but if you don't do that, you'll have to also pass the destination address with every packet you want to send over the socket as how else would the socket know where to send this data to?
Advantage is that you can use a single socket to send packets to different socket addresses. Once you have your socket configured and maybe even connected, consider it to be a bi-directional communication pipe. You can use it to pass data to some destination and some destination can use it to pass data back to you. What you write to a socket is send out and what has been received is available for reading.
A port is just a simple number. The combination of source port and destination port identify a communication channel between two hosts. Also the packet has a source port since without such a source port, a server could only have one connection to one IP address at a time. The source port makes it possible for a server to distinguish otherwise identical connections: they all have the same destination port, e. And when the server sends back replies, it will do so to the port the request came from, that way the client can also distinguish different replies it receives from the same server.
The port was the easiest part, it is just a unique identifier for a socket. A socket is something processes can use to establish connections and to communicate with each other. Tall Jeff had a great telephone analogy which was not perfect, so I decided to fix it:.
An application consists of pair of processes which communicate over the network client-server pair. These processes send and receive messages, into and from the network through a software interface called socket.
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