The TCP/IP model divides the communication space into:
- Physical layer (wires)
- Channel layer (data link)
- Transport layer (routing)
- Application layer (programs)
The first 2 levels are related to physical wires (fiber optics/coaxial cable) and methods of transmission of electrical impulses inside. All information is coded as 0 or 1. Conversion of electrical signal into digital occurs at the channel level.
The transport layer is related to the hardware that supports information systems. If you are into DevOps, you will understand and be interested in this. Everything you see on the screen/web pages is related to the last, application layer.
Let's see what we see when we scan ports for specific addresses (IP):
In addition to the TCP/IP model, there is the OSI Model. In it, you will find more levels of abstraction, which I personally find tedious. The entire programming community is still located in the Application Layer (present in both models).
As you can see on the scanner in the picture, there are other protocol levels. For example, HTTP/HTTPS work on top of TCP/IP. DNS exists as an internal DB for routing. Everything is important and spins in its place. Conventional scanners will not show you the lower levels of the model, because their level of detail covers only the application level.
At the bottom of the screen are bytes of information containing values 0-f (0-15). This is how information is encoded in files and transmitted via communication means. Also, in the case of HTTPS, there may be additional encryption (CRC code) with a distorted bit sequence to make it impossible to intercept traffic. A very convenient, but complex structure.
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