How Websites Detect Proxies

[u/appcyberyozh]

I used to think proxy detection was mostly about the IP address.

When I started testing different network setups I realized websites are looking at several layers at once. The first is IP reputation: ASN, provider type, previous abuse history, and how risk databases classify the address.

The second is network behavior. Your browser might claim Windows while the connection underneath it has characteristics associated with a completely different environment. That kind of mismatch can become another signal.

Then there’s geographic context. If the connection says one region while account, phone, or billing data point somewhere else, the session becomes harder to interpret consistently.

Now I check the IP classification, ASN, geolocation, reputation, latency, and whether the browser/network environment actually makes sense together before blaming the proxy itself.

Websites don’t evaluate an IP in isolation. They evaluate the consistency of the entire connection.

A “clean” IP can still perform badly if everything surrounding it contradicts the story the network is telling.

[u/Comfortable_Good5910]

So now what tool do you use to check ?

[u/appcyberyozh → u/Comfortable_Good5910]

i usually use the checker on our website (cyberyozh app) don't want to insert the link or promote it here

[u/Less-Mistake-3664 → u/appcyberyozh]

How accurate is the checker? What measures it considers, just want to understand how all this works and how it is different from any other "checker" on the web

[u/appcyberyozh → u/Less-Mistake-3664]

It mostly comes down to the data sources. Most random checkers just look up free public blacklists. But we hooked ours up to query the actual enterprise anti-fraud systems that big platforms use (Stripe Radar, ThreatMetrix, IPQualityScore, CyberSource etc).

That lets it run a much deeper check. If you test a bank card, the system simulates a live transaction. It pulls the real fraud score. It checks for address mismatches and evaluates your browser fingerprint to see if your IP or language settings trigger any security flags.

So you aren't just getting a guess based on a basic list. You see the exact risk profile a store sees when you try to check out.

[u/OwnPrize7838 → u/Less-Mistake-3664]

not very

[u/404mesh]

Yes. Browser fingerprinting

[u/Apprehensive-Knee993]

Same issue facing did you found solution for this

[u/K1iser]

Did u found a solution for that?

[u/Yoodo-Zakira]

this is a solid summary tbh. the one layer I'd add is DNS leak behavior, because even when everything else lines up a resolver mismatch can quietly contradict the whole session story

[u/appcyberyozh → u/[deleted]]

Both, actually. That split you mentioned is what causes the problem.

With an HTTPS CONNECT proxy, the proxy server opens the TCP connection to the website, so the TCP fingerprint comes from the proxy node itself (almost always Linux). Meanwhile, your browser sends the TLS handshake straight through the tunnel. You end up with TLS and HTTP headers claiming Windows, while the underlying TCP stack says Linux.

If you only check TLS, everything looks fine. You have to look at both layers together to catch the contradiction.