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Socket and ports

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In common language we can say that the socket is one of the most primal technologies of computer networking.

Socket and ports

     

In common language we can say that the socket is one of the most primal technologies of computer networking. Sockets are just like an end-point of two-way communication, which allow applications to communicate using network hardware and operating systems. However in case of java never get confused with a socket. Socket classes are used to establish a connection between client program and a server program. In java there is a java.net package, which provides two types of classes- first is ordinary socket, which implement the client side connection and second is server socket, which implement the server side connection.

The main purpose of the server socket is to listen an incoming connection request and ordinary socket is used to ask to server for the connection. Once a connection between client and server established, both the connected socket can communicate with each other.  
 
In other hand we can consider the work of port in connection-based communication is like a medium through which, an application establish a connection with another application by binding a socket by a port number. Addressing the information and the port no., accompanied the data transfer over the network. The Ports are used by TCP and UDP to deliver the data to the right application, are identified by a 16-bit number.

 
It will take effect of registering the application with the system to receive all data bound for that port. There is a limitation for the port that no port can be bound by two applications at the same time.

Introduction of networking Ports

In computer networking of connection-based communication port is like a medium through which, an application establish a connection with another application by binding a socket by a port number. Addressing the information and the port no., accompanied the data transfer over the network. The Ports are used by TCP and UDP to deliver the data to the right application, are identified by a 16-bit number present in the header of a data packet. Ports are typically used to map data to a particular process running on a client. If we consider a letter (data packet) sent to a particular apartment (IP) with house no. (port no), at this time the port no. is the most important part for the delivery of the letter. In order for the delivery to work, the sender needs to include an house number along with the address to ensure the letter gets to the right destination. 

If we consider the client-server architecture, a server application binds a socket to a specific port number in connection-based communication. It registered the server with the system where all the data destined for that port.

Now we are aware of the importance of the port number. In the same order there are some ports which are predefine and called reserved ports. Some of them are given below :-

Reserved port numbers.
Service Port no.
echo 7
daytime 13
ftp 21
telnet 23
smtp 25
finger 79
http 80
pop3 110
       
If we consider the range of the port numbers, there are 0 to 65,535 ports available. The port numbers ranging from 0 - 1023 are reserved ports or we can say that are restricted ports. All the 0 to 1023 ports are reserved for use by well-known services such as FTP, telnet and http and other system services. These ports are called well-known ports.

   

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Posted on: June 16, 2009

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Comments
Sidra Riaz
September 20, 2011
Computer science

Everything is well defined here
chandra shekhar swain
February 15, 2012
need of port in socket programming

it is better.not best level document it should be focused on why we use port.if not use port in socket then what problem we will face
good answer......
April 7, 2012
socket and port

godd reply....
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