Note that once an application binds itself to a particular port, that port can not be used by any other application. It is first come, first served. This all probably still feels confusing to you, and there is nothing wrong with that, as this is a complicated concept to grasp. Therefore, I will give you an example of how this works in real life so you can have a better understanding.
We will use web servers in our example as you all know that a web server is a computer running an application that allows other computers to connect to it and retrieve the web pages stored there. In order for a web server to accept connections from remote computers, such as yourself, it must bind the web server application to a local port. It will then use this port to listen for and accept connections from remote computers.
Web servers typically bind to the TCP port 80, which is what the http protocol uses by default, and then will wait and listen for connections from remote devices. Once a device is connected, it will send the requested web pages to the remote device, and when done disconnect the connection.
On the other hand, if you are the remote user connecting to a web server it would work in reverse. Your web browser would pick a random TCP port from a certain range of port numbers, and attempt to connect to port 80 on the IP address of the web server. When the connection is established, the web browser will send the request for a particular web page and receive it from the web server.
Then both computers will disconnect the connection. Now, what if you wanted to run an FTP server, which is a server that allows you to transfer and receive files from remote computers, on the same web server.
Therefore, the FTP server application when it starts will bind itself to TCP ports 20 and 21, and wait for connections in order to send and receive data. Most major applications have a specific port that they listen on and they register this information with an organization called IANA.
With developers registering the ports their applications use with IANA, the chances of two programs attempting to use the same port, and therefore causing a conflict, will be diminished. Every machine on the the Internet has a unique number assigned to it, called an IP address. Without a unique IP address on your machine, you will not be able to communicate with other devices, users, and computers on the Internet.
You can look at your IP address as if it were a telephone number, each one being unique and used to identify a way to reach you and only you. Have you ever been connected to your computer when something strange happens? A CD drive opens on its own, your mouse moves by itself, programs close without any errors, or your printer starts printing out of nowhere?
When this happens, one of the first thoughts that may pop into your head is that someone has hacked your computer and is playing around with you.
Then you start feeling anger tinged The Internet is a scary place. Recommended Reading. A must buy for anyone looking to get good at networking. Reserved; do not use but is a permissible source port value if the sending process does not expect messages in response. BGP Border Gateway Protocol - an exterior gateway routing protocol that enables groups of routers to share routing information to ensure efficient and loop-free routes can be established.
Well explained! Then this IP address will also be converted to binary digits bits. All this process of converting the domain name to an IP address helps the computer to understand as we all know that computers only understands 0 s and 1s.
ICMP is a network layer protocol. The key difference between Telnet and SSH is that SSH uses encryption, which means that all data transmitted over a network is secure from eavesdropping. This site uses Akismet to reduce spam. Learn how your comment data is processed. By ICANN there are three categories for ports: From 0 to — well known ports assigned to common protocols and services From to — registered ports assigned by ICANN to a specific service From to 65 — dynamic private, high ports range from 49, to 65, Can be used by any service on an ad hoc basis.
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