FWIW, I do get that it is its own method and I understand the intent of the specification (and thereby why it "wouldn't matter" in that worldview), but it feels weirdly non-HTTP for this functionality to not be treated as a resource... but like, I guess "fair enough" in that (looking at it again) the existing old-school proxy CONNECT method also has this flaw :/. I just feel like people should be able to easily "mount" functionality onto their website into a folder, and by and large most HTTP methods support this, with the ability to then take that sub folder and internal-proxy it to some separate backend origin server (as like, I would want to take the flows for anything under /secret/folder/--whether GET or PUT or PROPPATCH or CONNECT-IP--and have my front-end http terminator be able to transparently proxy them, without having to understand the semantics of the method; it could very well be that I am just living in a dream of trying way too hard to be fully-regular in a world dominated by protocols that prefer to define arbitrary per-feature semantics ;P).

I guess I am also very curious why you aren't defining this over WebTransport (which would allow it to be usable from websites--verified by systems like IPFS--to build e2e-encrypted raw socket-like applications, as I imagine CONNECT-IP won't be something web pages will be able to use). (For anyone who reads this and finds this thought process "cool", talk to me about Orchid some time, where I do e2e multi-hop VPN over WebRTC ;P.)

The Great Firewall does probing for ages now. It pauses the connection and sends its own request, checking what kind of protocol the server returns. Nothing stops these firewalls from trying ‘connect-ip’. The path could be used as a secret ‘key’ to thwart too-curious firewalls (though the protocol probably won't do much against DPI anyway).

Why not just require authentication?

The goal is to look like normal boring traffic.

The parent is talking about having the firewall attempt its own request, not some kind of sniffing (which shouldn't be possible with TLS)

It would then be weirdly important that a mis-authenticated CONNECT-IP then look the same as if CONNECT-IP were not implemented, as opposed to returning an authorization error of some kind (which seems weirder than hiding the method via the path).

True. But the path method has issues too, like, how would you implement that with HTTP 1.1? The "path" field is actually part of the target, so you would have to send the request like `CONNECT-IP https://remote-server/mount-point` which seems backwards. (EDIT: and also you still need to make sure you don't give the wrong kind of error if the path is wrong, like a 404 instead of a 501 not implemented or whatever)

As a possible solution for the discovery by authorization error problem, maybe a convention could be established where an authorization error is returned by default if CONNECT-* isn't configured.

Huh. It is possible that I simply didn't understand the spec, as I was (and am...) pretty sure that CONNECT-IP (at least at the HTTP semantics level) just takes a path (and only /)--like GET--without an associated "extra" authority, as it is creating an IP tunnel: there is no remote host (as there would be with an old-school CONNECT); like, what is the "target" here? I am just talking to the server and asking it to give me an IP bridge, right? What does "remote-server" represent to an IP tunnel?

You're right, I misunderstood the usage. That does make the possibility of using the path more compelling

I guess authentication via https before ‘connect-ip’ would work. Or, authenticating with headers in the same first ‘connect-ip’ request, if the server responds with ‘invalid method’ when not authenticated.

By the way, probing at connection time, that I mentioned in my original comment, isn't actually necessary. The GFW will just scan known popular-ish hosts, trying ‘connect-ip’ and banning everything that works as a proxy. (Connection-time probing would just make it easier to discover the hosts, such that collecting the IPs and stats separately is not needed.)