[moreati]

Why would one want this? Are there particular situation(s) that it's desirable to detect a TCP proxy? Does presence of a TCP proxy indicate some adverserial behaviour? E.g. surveillance, censorship, a particular attack?

[userbinator]

Surveillance, on the part of those who want to do this fingerprinting.

[dlenski]

Came here to ask the same thing. Why do I _care_ if connections to my server come from a TCP proxy? Particularly when a VPN is _not_ observable in a similar way?

Is there some class of bad actors who extensively use TCP proxies and not only _don't_ use VPNs, but would incur large costs in switching to them?

[JDye]

Web scrapers maybe aren't "bad actors", but many sites dont want them. They'll use tons of TCP proxies which route them through a rotating pool of end user devices (mobiles, routers, etc...). Its not really possible to block these IPs as you'd also be blocking legitimate customers so other ways to detect and block are required.