Is it possible to access the proxy "manually"? && How?

Question

proxy

Is it possible somehow from PHP to access the proxy, and not to the site through it? So that the request should be sent to the proxy address and pass the site address in some parameters?

Answer 1

If we are talking about an HTTP proxy, then there are two options:
1. As an HTTP proxy, while a regular HTTP request is made to the proxy with the only difference: not a relative path is passed as an argument, like GET / HTTP/1.0, but a full URI with indication of the protocol

GET http://example.com/ HTTP/1.1
Host: example.com

2. As a CONNECT proxy, a request is made

CONNECT example.com:80 HTTP/1.1
Host: example.com:80

after which the server response is read, if the response is successful, then further data transmitted through the connection will be proxied to the server port specified in CONNECT.
The second method is usually used for HTTPS, some proxies do not allow CONNECT on ports other than 443.