this post was submitted on 05 Oct 2023
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If a packet is traversing an ISP's network the ISP should have to know where it is coming from and where it is going, right? So even if you "encrypt the first hello" packet, the ISP would still know where it was routed, right?
I'll freely admit I have only a very basic (and likely outdated) understanding of IP networking, but I don't see how this protects my browsing habits from my ISP. Even if they can't understand my "hello" to lemmy.ml, they still know I'm talking to lemmy.ml's IP address about something.
What am I missing?
Your ISP is mostly going to be seeing AWS, Azure, GCP, Cloudflare, etc IP addresses.
They would know you’re talking to that IP, not necessarily lemmy.ml. It is very common for multiple sites to be hosted on the same ip. The reason SNI exists is so the browser can tell the server which site it was looking for in an encrypted session. If it is 1:1 then it would be true.
When you type in www.example.com, you request the IP of the server for that site using a DNS server. The DNS server sends you the IP and then you connect to it. If they are using https for DNS it means that your ISP or onlookers have to reverse which domain you're accessing from that IP to know that you're accessing www.example.com.
At least I think that's what is happening.
The problem doesn’t involve DNS, it’s after that step.
SNI is when your browser connects to the server. A server may host multiple sites on the same IP, so your browser says “I would like to open an encrypted session to lemmy.ml”. It does this in the clear. If it was an unencrypted http site it would be in headers, but in https those headers aren’t passed until after the encrypted session is set up, so there has to be some way for the server to know the specific site. Anybody listening to SNI traffic knows the exact site you connected to, even if there are hundreds at that ip.
This adds a public key to the DNS record, so your browser is able to encrypt that initial hello message before the https session is encrypted. Someone listening might see something like “ECH: randomgibberish” but the server can decrypt it.
If I understand correctly, someone other than your ISP could see the name of the website, since it isn't encrypted. I think it would bounce through several servers that could possibly read the data.
This makes it so that your ISP doesn't see the actual name of the server/site you're communicating with, only the IP address. Without Encrypted Hello they're able to see both.
I would think that an IP address tells you the domain name by doing a simple DNS lookup.
In many cases you can, but there's never a guarantee that a given IP address will have reverse DNS records configured for resolve it into. On top of that, if it's a major site it's likely hosted behind a content delivery network that may a share a single IP address across thousands or even millions of completely unrelated servers. Cloudflare does some pretty interesting stuff with that approach: https://blog.cloudflare.com/cloudflare-servers-dont-own-ips-anymore/ edit: bad at typing
Cloudflare fronts much of the internet, so all your ISP would see is that you connect to cloudflare, not which site you actually connect to.
In fact this was a big reason cloudflare and Amazon were angry with the signal foundation, for using domain front running, using the same trick in fascist countries to still be able to talk to signal servers
Yeah I think it has the same limitations that pretty much anything not through a vpn has because you still have to tell your isp where to send the data. Your isp will still see some things, even if it’s encrypted (metadata, DPI, habits, and things beyond my knowledge). This sounds like a step in the right direction for the majority of people though, even if it’s minor.
I kind of see it like differentiating between them seeing lemmy.ml via this vs lemmy.ml/thing-i-want-private/peronal.html without it, but I could be wrong about that.
HTTPS already prevents them from knowing exactly what content you’re looking at. Hiding SNI prevents them from knowing exactly what site you are connecting to via HTTPS.
They can still figure that out if you’re using unencrypted DNS or if there is a 1:1 IP to rDNS mapping though.