Russia blocked it for Cloudflare because the outer SNI was obviously just for ECH but that won't stop anyone from using generic or throw-away domains as the outer SNI. As for reasonable I don't quite follow. Only censorious countries or ISP's would do such a thing.
I can foresee Firewall vendors possibly adding a category for known outer-SNI domains used for ECH but at some point that list would be quite cumbersome and may run into the same problems as blocking CDN IP addresses.
They were wrong then, of course, and they're still wrong now.
Because I can ping almost any public server on the internet and they will reply. I can ping your website just fine and it replies to me!
But for example, our firewall at work responds to ICMP but all of the endpoints which aren't meant for public use do not. That is less because ICMP is a problem and more because everything works fine without it and least privilege is good design.
ICMP is also more than just ping, and some parts of ICMP are considered a vulnerability if exposed to the public internet by some scanning services.
I could be convinced to block inbound pings. Anything past that and I'd want solid evidence that it wouldn't break anything, with the expectation that it would.
In the snooping-mandatory scenario, either you have a mandatory outbound PAC with SSL-terminating proxy that either refuses CONNECT traffic or only allows that which it can root CA mitm, or you have a self-signed root CA mitm’ing all encrypted connections it recognizes. The former will continue functioning just fine with no issues at providing that; the latter will likely already be having issues with certificate-pinned apps and operating system components, not to mention likely being completely unaware of 80/udp, and should be scheduled for replacement by a solution that’s actually effective during your next capital budgeting interval.
Eventually these blocks won't be viable when big sites only support ECH. It's a stopgap solution that's delaying the inevitable death of SNI filtering.
Big sites care about money more than your privacy, and forcing ECH is bad business.
And sure, kill SNI filtering, most places that block ECH will be happy to require DPI instead, while you're busy shooting yourself in the foot. I don't want to see all of the data you transmit to every web provider over my networks, but if you remove SNI, I really don't have another option.
> require DPI
Enterprises own the device that I'm connected to the network with, I don't see how you can get any more invasive than that.
> countries with laws
1) what countries do national-level SNI filtering, and 2) why are you using a hyptothetical authoritarian, privacy invading state actor as a good reason to keep plaintext SNI?
> Big sites care about money
Yes, and you could say that overbearing, antiquated network operators stop them from making more money with things like SNI filtering.