How are sites actually detecting proxy/VPN traffic now?

DICloak Browser said:

403 is just the loud version. More CAPTCHAs, forced logins, missing results, or sudden rate limits can all be soft flags. Compare the same action on a normal connection or a fresh browser profile. If only the proxy setup gets treated differently, that’s usually the clue.

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1. same profile, new IP → still flagged = it's not the IP
2. new profile, same IP → clean = confirmed, its the profile

CanProxies said:

Youre right that its not reputation lists, or at least thats not the part thats getting you. If clean residentials burn in a day or two, the IP isnt the signal — it's just what gets attributed after something else fires.

TLS: yes, but JA3 specifically is less useful than people think now. Chrome permutes its ClientHello extension order and pads with GREASE, so a naive JA3 hash isn't even stable across connections from the same browser. Detectors moved to JA4 and, more importantly, to coherence: the giveaway usually isn't "your JA3 is on a list", it's "your TLS handshake says Go/Python but your User-Agent says Chrome 128". Contradiction, not identity.

I tested exactly this. TLS-impersonation library against an Akamai-protected target, with a warm session and 13 cookies in the jar — still 403. Same proxy, same IP, real headful Chrome — straight through. So it wasnt session state and it wasnt the address. It was the client stack.

WebRTC is a real leak but usually not your main problem — it doesn't route through an HTTP/SOCKS proxy by default so STUN can expose your actual address. Worth checking once, it's a quick fix, then stop thinking about it.

Timing/behaviour matters more than most people accept. Not just mouse movement — the shape of your request sequence. Humans don't hit endpoints in perfect order at regular intervals.

And to your actual question: no, rotating the IP does not clear a burned fingerprint. Cookies, localStorage, IndexedDB, service workers, canvas/audio/font entropy and your TLS stack all follow the profile, not the address. New IP + same profile = same entity. And the reverse is telling — new profile on the same IP often works fine, which shows you where the weight actually sits.

Cheapest way to find out which layer is leaking, seperately, two runs:

1. same profile, new IP → still flagged = it's not the IP
2. new profile, same IP → clean = confirmed, its the profile

That isolates it in an afternoon instead of months of buying "cleaner" proxies.

The general principle — a mobile IP in one country with a mismatched locale, a timezone from somewhere else, and a datacenter-shaped TLS stack is a set of contradictions. Any one alone is unremarkable. Together theyre a signature.

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caeleccae said:

With my own observations and what I have experience so far I think sites use multiple factors to detect proxy or VPN traffic these include
* Ip reputation
* Behavior Patterns
* Geolocation mismatches

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Daniel-Brooks said:

From what I've seen, it's not just the IP anymore. Many sites also look at browser fingerprint, device details, and unusual behavior patterns, so changing only the IP doesn't always solve the problem.

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