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Comment by Reason077 | Hacker News Reader

Interesting. UK ISPs have had a similar block/filter list for many years (mostly covering copyright-infringing torrent websites and the like). But it’s more robust than a simple DNS block. A VPN can bypass the block, but changing DNS providers will not.

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What / how do they do it then? SNI inspection?

The ISP's blackhole the IP for some blocked domains. So changing your DNS to 8.8.8.8 will resolve the domain, but the IP won't work. A VPN avoids this, since the traffic goes via the VPN IP.

How would that work with cloudflare and similar though?

Cloudflare works with the UK government to facilitate blocks within their infra, I assume in exchange for being allowed to access UK network infrastructure.

In the case that a blocked site resolved to a Cloudflare IP, it would likely be kicked off of Cloudflare, or geo-blocked for UK users (by Cloudflare).

https://www.ispreview.co.uk/index.php/2025/07/cloudflare-blo...

Ironically that url is forbidden for me, I was under the impression that CF were fairly anti censorship, or at least they inferred that they should not be the one calling the shots (in reference to kiwifarms)

Wow that’s intense.

I remember hearing someone complain on HN of their site getting blocked because it shared an IP with an illegal soccer livestream. I can’t imagine they’re doing this to IP blocks owned by CDNs like Fastly, CloudFlare, or CloudFront though. Or are they? Does this regularly break most of the internet for UK customers?

Spain ISPs block CloudFlare IPs during La Liga matches.

Do you have a source for this claim?

TBH it is not ALL cloudFlare IPs but a significant quantity of sites using and not using CF CDNs. You cannot imagine what a pest that is even for legit users of legit collateral damage pages. CloudFlare is in the courts appealing/countering initial court allowance to blockade and ISPs are bound to comply to blackout requests. You can look at https://hayahora.futbol (traslation: is there soccer match now?) to see affected domains.

https://protonvpn.com/blog/spain-laliga

While I am not some reputable source per-se, I have some tailscale presence over there and can corroborate my exit nodes find cloudflare sites blanket blocked on weekends.

In that case it like someone controlling the DNS records for a banned site could cause some mischief

I've never hit one. Flipping DNS works for (for example) Anna's Archive. Have you got an example?

Transparent DNS proxies on ISP side. Easy thing for them.

DNS over HTTP is a thing also, though.

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