How is a socket different from a port

Each client connected to the server will have either a unique IP address or port number or both. These two articles may help clear up some confusion. Usually the main-socket resided in a folder called 0. In MCP, the port is described as a range of protocol-enabled connections, that are available through the Port Handler.

It holds the back-end security of the network. Additionally, the socket can can also be designated by a port range number, and it is initiated when any back-end secure channel is established. Or, 1 to ? I know I am being picky, but given the complexity and detail of the rest of the information, which my old fart brain would have to go back and spent hours to study, I would want to be sure I was not shooting arrows into a forest and hoping to kill a deer.

I mean, what with all those fancy-pancy certifications I never got. The source and destination fields in the headers are 2 bytes long. However, I believe that port 0 is not supposed to be use, so the actual range should be You would be surprised how old I felt when I found out my old farmer friends, where I grew up, knew everything about Facebook and I knew nothing about it! No Account? Sign up. By signing in, you agree to our Terms of Use and Privacy Policy. Already have an account? Sign in.

By signing up, you agree to our Terms of Use and Privacy Policy. Enter the email address associated with your account. Connection states — if you are wondering what established and listening and the other state descriptions mean. Online port tester Collection of tools for port scanning and web server testing. I have a problem with an application that uses fixed source ports in the communication with the server.

If the communication ends for some reason the clients tries to put the communication up again using the same source port. I have a software which creates 4 sockets with apparently random numbers the person who developed left no documentation.

Is there a way to interconnect those random number sockets and port so the client is able to connect to the software? Hi It sounds like the software is supposed to be a server which usually has fixed ports. What does the software do?

It receives video data, connects to a MariaDB server, and serves as an API to it, receiving calls from a mobile app and sending customer data back. I wonder if the reason why it opens 4 sockets is to receive and send video data and receive and send customer data. Either way, the problem is that it creates sockets of random numbers instead of a port which is what the android app uses. When you say it receives video data I assume that that is coming in on a port.

The database would need another. The mobile app is used to view the video I assume. Is any part of it working. Where is the mobile App located internet or same network. Is this a standard kit or is it put together by yourself?

Rgds Steve. The software creates 4 sockets with random port numbers but none of them are the port which the APP uses. The mobile App is on the internet. The software connects to a tunnel connection I tried to use ssh -D Does it have any setup instructions. Is it off the shelf software and does it have a website that I can take a look at. It is a bespoke software made by a person who left the company and never left any documentation.

Hi, I have a question, is it possible for me to run 2 applications and connect to different ip but using same port number example ? Yes you are doing that when you connect to two different websites as they both use port 80 rgds steve. So I have a question. Can server A somehow restrict me and only allow connections to the port on the remote server B and not allow me to connect me to any other port on remote server B?

Have you seen such a restriction before and if yes then what would be the reason behind such a restriction? Thank you.

Not quite sure exactly what restriction you mean but you can restrict on destination port and ip and source port and IP if that helps rgds steve. Hi Steve, So here is the scenario. The webserver A has the port open for any incoming requests. The webserver A hosts a website and one of the pages of that website has C code which makes API calls to a remote server B. So my questions are:- 1.

Is it possible for the network admin to disallow API calls to ports other than ? What could be the reason for such a restriction? After all, how can restricting a destination port give you any sort of advantage?

Port is just a number on which the server listens. Please help. 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. 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. There is a house that wants to communicate with other house. Here, house is analogous to a process, and door to a socket. Sending process assumes that there is a infrastructure on the other side of the door that will transport the data to the destination.

Once the message is arrived on the other side, it passes through receiver's door socket into the house process. This illustration from the same book can help you: Sockets are part of transport layer, which provides logical communication to applications. Thus a socket is not a connection itself, it's the end point of the connection.

Transport layer protocols are implemented only on hosts, and not on intermediate routers. Ports provide means of internal addressing to a machine.

The primary purpose it to allow multiple processes to send and receive data over the network without interfering with other processes their data.

All sockets are provided with a port number. When a segment arrives to a host, the transport layer examines the destination port number of the segment. It then forwards the segment to the corresponding socket.

This job of delivering the data in a transport layer segment to the correct socket is called de-multiplexing. The segment's data is then forwarded to the process attached to the socket. A socket is one endpoint of a two-way communication link between two programs running on the network.

A socket is bound to a port number so that the TCP layer can identify the application that data is destined to be sent to. The building number of the "Bank" is analogous to IP address. A bank has got different sections like:. So 1 savings account department , 2 personal loan department , 3 home loan department and 4 grievance department are ports. Now let us say you go to open a savings account, you go to the bank IP address , then you go to "savings account department" port number 1 , then you meet one of the employees working under "savings account department".

These are all socket descriptors. Likewise, other departments will be having employess working under them and they are analogous to socket. A socket is a structure in your software. It's more-or-less a file; it has operations like read and write. It isn't a physical thing; it's a way for your software to refer to physical things. A port is a device-like thing. Each host has one or more networks those are physical ; a host has an address on each network.

Each address can have thousands of ports. One socket only may be using a port at an address. Once the port is allocated, no other socket can connect to that port. The port will be freed when the socket is closed. The term port also refers to certain Ethernet connection points, s uch as those on a hub, switch, or router. In layman's terms:. A PORT is like the telephone number of a particular house in a particular zip code. The ZIP code of the town could be thought of as the IP address of the town and all the houses in that town.

A SOCKET on the other hand is more like an established phone call between telephones of a pair of houses talking to each other. Those calls can be established between houses in the same town or two houses in different towns. In a broad sense, Socket - is just that, a socket, just like your electrical, cable or telephone socket.

A point where "requisite stuff" power, signal, information can go out and come in from. It hides a lot of detailed stuff, which is not required for the use of the "requisite stuff". A Port is an endpoint discriminator. It differentiates one endpoint from another.