Comment by Sakura-sx

First of all, thanks!

I imagine any big CDN implementing something like this could keep a database of all of this, combined with the old kind of IP intelligence and collecting not only RTT on other protocols like TLS, HTTP, IP (aka ping, and traceroutes too), TCP fingerprint, TLS fingerprint, HTTP fingerprint...

And with algorithms that combine and compare all these data points, I think very accurate models of the proxy could be made. And for things like credit card fraud this could be quite useful.