How is the interaction between the client and the proxy server at a low level?

Question

Computer networks

Good time!
Interested in the question, how does the proxy find out information about which address I need to go to? Where is this information contained? At what point is it created and specializes in a proxy? At what OSI level are frames with proxy fields?
I feel a fundamental misunderstanding in this topic and I want to understand.
Thanks to all!

Answer 1

When you have direct interaction configured, your browser resolves google.com to 188.43.61.182 and sends a fully formed HTTP request to its port 80.
When you have configured interaction through a proxy (7.7.7.7:3128) the same HTTP request (almost unchanged, see below) will be sent by the browser to port 3128 of address 7.7.7.7 . If there is a proxy and he agrees to serve you, he will redirect your request from his IP and dynamic port to the true 188.43.61.182 . This is the first approximation.
The nuances are
1) who - the client or the proxy - will resolve
2) additional HTTP client authorization fields before the proxy
3) additional HTTP client information fields that the proxy will insert into the request
, etc. etc.

Answer 2

Takes the client's request and passes it to the destination server on its own behalf, receives the server's response and returns it to the client.
For the client, this is actually transparent, since the proxy receives the answer, it can do anything with it and give it to the client in the form that you decide.

Answer 3

See how to filter. By ip on the 3rd, by ports on the 4th, etc.