Glossary · Detection & reputation
X-Forwarded-For
An HTTP header a proxy can add to name the original client's IP, and the single biggest tell that separates an anonymous proxy from a transparent one.
X-Forwarded-For is a header that carries the address of the client a request was forwarded on behalf of. It exists for a legitimate reason: a server sitting behind a load balancer needs some way to recover the real visitor's IP. But when a forward proxy adds it, the header quietly hands the destination the very address the proxy was supposed to hide.
This is what proxy anonymity grades actually measure. A transparent proxy passes your real IP straight through in X-Forwarded-For or a related header, so it changes your route but not your identity. An anonymous proxy hides your IP but still announces that a proxy is in use. An elite proxy sends neither tell, so the request looks like an ordinary direct connection.
For anyone choosing a proxy, this header is the difference between privacy and the illusion of it. An address can change where traffic appears to come from and still leak who is behind it in one header, which is why the anonymity grade matters as much as the IP itself.
How HProxy handles it
Our checker inspects exactly these headers on every free proxy and grades it elite, anonymous or transparent from what it actually sends, rather than trusting the label a source attached to it.
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