Port: It is a software vulnerability in operating systems and the number of these vulnerabilities ranges between 0 – 65,536 software vulnerabilities, and each vulnerability works on a different protocol from the other.
Software vulnerability: a slot or gateway in all operating systems to organize the entry and exit of “data”. Each device has several ports for crossing and exchanging data and communicating between you and other computers and servers.
Each protocol has its own port number that is pre-assigned by the IANA, port numbers from 0 to 65535. For example, web servers that we connect to to browse websites via HTTP usually use port 80, FTP uses port. 21, SMTP usually uses port 25 …
Every server or application has a specific port that it uses to send and receive data on it, so when data comes to the device on a specific port, the device will know which application this data belongs to and sends it to the application that processes it.
When you browse the Internet using Opera, Google Chrome, or any other browser, you are using Port: 80
When you upload a file then you use Port: 21.
The browser:
When we browse the internet using any browser such as Google Chrome, Firefox, Opera and others. This means that we are located at the top of the OSI Layers, which is the Application Layer, where we deal with a protocol such as HTTP, which is one of the protocols used in the communication process between the Browser and the different web servers, this protocol makes a request for the page you want from the web server, which is waiting for a connection or connections from your browser on Port 80.
When we connect using the browser, our “local port” carries a random number higher than 1023, and the server waits for the connection on its port .. and its number (80).
We call it “Remote Port”.
If our machine is the Server .. then the “Local Port” is (80) and the “Remote Port” is 1024 or more.
Sockets:
We also know that each device connected on the network has its own IP address, which is what distinguishes it from other devices, however, the IP address alone is not sufficient to work on the network, as the computer can run more than one application or protocol at the same time, such as browsing the Internet, watching video streaming and Playing on the “Online gaming” network, so we need another title that distinguishes each application from other applications.
Just as the IP address distinguishes a computer from the rest of the network devices, so the Port number distinguishes applications or services from one another.
That is why the use of ports allows computers to run multiple applications at the same time “that is, on the same operating system”.
Every connection between two devices on the network needs what is known as a socket or socket for each device separately, as:
Socket = IP address + Port number
Imagine with me that you are using your personal computer at home, and you have two windows open in your browser, one for Google, and the other for Yahoo.
For the Google window. The connection will be as follows:
Your PC: IP1 + port: 60200 – Google server: IP2 + port: 80 (standard port)
Where IP1 + port: 60200 represents the socket of your device, “Client Socket”, while IP2 + port: 80 represents the socket of your device.
For the Yahoo site window. The connection will be as follows:
your PC: IP1 + port: 60401 —Yahoo server: IP3 + port: 80 (standard port)
Where IP1 + port: 60401 represents the socket of your device, “Client Socket”, while IP3 + port: 80 represents the socket of your device.
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