6 ms·

The ISP can just check which IP you contact, so I don't see this increasing privacy.

by im3w1l 7y ago

jeltz 7y ago
And until ESNI gets high adoption they can also just look at the SNI header. I do not see how DoH gives any significant amount of extra privacy.
- Someone1234 7y ago
  DoH doesn't need to provide extra privacy to make sense (although it is a mandatory stepping stone to good privacy). It also provides a difficult to block security upgrade (as opposed to DoT, which is easy to block). We've seen regular US ISPs hijack unencrypted DNS to insert content or replace sites entirely. We've also seen bad actors do far worse on public WiFi. So acting like DoH is a waste of time unless every part of the privacy puzzle is online is wrong-headed. It is a huge step in the right direction for privacy, increase their costs, and will be much needed when eSNI is online. In the meantime "all" we get is a huge security improvement.
  - corford 7y ago
    Except, not really. If you're worried about DNS tampering, DNSSEC already exists all the way up to the root servers. If you're worried about ISPs snooping on what sites you visit, they'll continue to be able to do this even with widespread DoH/DoT and ESNI adoption. You still need to connect to an IP and TLS certs still have unique serials (most of which appear on public CT logs). Correlated over a large user population, that's more than enough to get a pretty decent, aggregate view of what sites you're browsing (certainly enough to tailor ads/marketing towards you). As for random third party networks (e.g. Starbucks wifi), if you're not using a VPN then I don't see what expectation of privacy/security you had in the first place. Ultimately, if you don't trust your ISP (or whatever network you happen to be connected to), the only meaningful option is a VPN. Encrypting your DNS traffic to a resolver (whether with DoH or DoT) is, at best, a very incremental improvement in the arms race. It protects users against some of the most egregious ISP abuses (assuming said ISP doesn't also spoof the cert...) at the expense of potentially misleading them into thinking they have more privacy than they actually do. In the case of DoH it will also likely inadvertently end up centralising a huge chunk of DNS lookups in to the hands of a few large corporations thanks to it being opt-out rather than opt-in. At least DoT avoids that (and offers server-to-server encryption). Much better for users who want unfettered internet access and privacy to encrypt the whole lot with a VPN and use a resolver that validates DNSSEC. If the chain of resolvers were all DoT enabled that would definitely be a nice extra but hardly essential. Alternatively, if you're in a country with a healthy ISP market (and government you're not afraid of), there's always the option to simply move to a provider that doesn't tamper with and monetise user traffic.
    - tialaramex 7y ago
      > TLS certs still have unique serials In TLS 1.3 everything sent by the server, including its certificate, is encrypted. This is possible because of a re-ordering of considerations. It used to be that the conversation starts like this: Client: "Hi, I want to talk to Server?" Server: "Here's a certificate for Server, which is me" Client: [ "Secret is 123456" encrypted using the Public Key from the certificate for Server ] Server: [ "See, it's me" encrypted using the secret 123456 ] But in TLS 1.3 it starts like this: Client: "Hi, I want to talk to Server and I used ECDHE to pick this number 123" Server: "I used ECDHE and I picked 456..." [ "I am Server, here's a Certificate for Server, and here's a signature proving the conversation we're having right now is with me, Server, which you can verify using the Public Key in that Certificate" encrypted using the secret 987654 ] ECDHE allows Client and Server to agree the secret key 987654 even though the information they publish to agree on it (123 and 456) is public for anyone to see. Its predecessor Diffie Hellman is easier to understand if you never got past high school mathematics, so research that if you've never seen this trick before. You'll notice this is also less round trips (so better performance over high latency links) as well as being more secure and more future-proof.
      - corford 7y ago
        This is very cool. Thanks for the great explanation!
ekimekim 7y ago
This is addressed in TFA: The fact that there are multiple problems and solving any one of them doesn't help much until they're all solved, should not be an excuse to refuse to solve any of them.
- im3w1l 7y ago
  So you have a "solution" that doesn't really solve the problem, and also create a new privacy problem (now cloudflare has your data too). Hence it's actually a privacy loss.
hunter2_ 7y ago
For some (large, especially) sites, the IP address maps to the entity you're trying to contact. For others (small, especially) sites, the IP address is shared among many entities... not just shared origin hosts but also the massive reverse proxies of the world (Cloudflare, etc.).
- zzzcpan 7y ago
  There is an actual research on this. More than 90% of alexa's top 1 million websites (more like 95% or so) are uniquely identifiable just by IP addresses you connect to when you visit them. This is not a single IP address per website, but multiple, because websites include subresources with other IP addresses to connect to. On top of that, there is a pressure on CDNs and clouds to make websites stick to specific IP addresses and make them blockable by IP addresses without affecting other customers. So far they have proven to not go against this pressure and even made technical solutions to aid governments to identify websites by IP addresses, in particular by fixing L7 routing layer to block domain fronting (which is important, because ESNI is basically domain fronting, but crappy, and the pressure didn't go anywhere, so there is the same pressure to make sure ESNI doesn't interfere with identification of websites you are visiting).
  - wolco 7y ago
    How would they force cloud providers customers to host on an ip? Do you envision restrictig new instances with manual approvals required?
- judge2020 7y ago
  Also, Cloudflare does give Business and Enterprise customers their own IP addresses (although often rotated) so that these sites work with old non-SNI browsers.
mantap 7y ago
That doesn't work anymore. ISPs are not going to block AWS IP ranges or Azure IP ranges, etc. The cloud killed IP blocking. The pirate bay is supposed to be blocked in UK by court order, but because they use cloudflare it's still accessible and only DNS blocked.
- throw0101a 7y ago
  > ISPs are not going to block AWS IP ranges or Azure IP ranges, etc. Tell that to China, Iran, Turkey (?), etc.
  - ru552 7y ago
    Ok, authoritarian regimes not included
    - throw0101a 7y ago
      > Ok, authoritarian regimes not included And yet this was/is one of the justifications for implementing this. They're not doing it in the EU because (a) there are decent privacy laws, and (b) IP addresses are (IIRC) considered personal information and so Cloudflare DoH would be responsible for keep a whole bunch of data safe. They may not want that responsibility. This seems to (currently) be US-only because of the sucky US privacy laws.
      - mantap 7y ago
        No the justification is to make it harder for non-authoritarian countries to block websites. If China or North Korea want to block the IP range of AWS+Azure+Google that's up to their respective autocrats. Most democratic or even hybrid regimes are not prepared for that level of absolute chaos and consequent protest if half the Internet is shut down. You can only pull that shit in a dictatorship.
- gsich 7y ago
  Blocking wasn't the point in the post above.

The ISP can just check which IP you contact, so I don't see this increasing privacy.

by im3w1l 7y ago

The ISP can just check which IP you contact, so I don't see this increasing privacy.

And until ESNI gets high adoption they can also just look at the SNI header. I do not see how DoH gives any significant amount of extra privacy.

Someone1234 7y ago
DoH doesn't need to provide extra privacy to make sense (although it is a mandatory stepping stone to good privacy). It also provides a difficult to block security upgrade (as opposed to DoT, which is easy to block). We've seen regular US ISPs hijack unencrypted DNS to insert content or replace sites entirely. We've also seen bad actors do far worse on public WiFi. So acting like DoH is a waste of time unless every part of the privacy puzzle is online is wrong-headed. It is a huge step in the right direction for privacy, increase their costs, and will be much needed when eSNI is online. In the meantime "all" we get is a huge security improvement.
- corford 7y ago
  Except, not really. If you're worried about DNS tampering, DNSSEC already exists all the way up to the root servers. If you're worried about ISPs snooping on what sites you visit, they'll continue to be able to do this even with widespread DoH/DoT and ESNI adoption. You still need to connect to an IP and TLS certs still have unique serials (most of which appear on public CT logs). Correlated over a large user population, that's more than enough to get a pretty decent, aggregate view of what sites you're browsing (certainly enough to tailor ads/marketing towards you). As for random third party networks (e.g. Starbucks wifi), if you're not using a VPN then I don't see what expectation of privacy/security you had in the first place. Ultimately, if you don't trust your ISP (or whatever network you happen to be connected to), the only meaningful option is a VPN. Encrypting your DNS traffic to a resolver (whether with DoH or DoT) is, at best, a very incremental improvement in the arms race. It protects users against some of the most egregious ISP abuses (assuming said ISP doesn't also spoof the cert...) at the expense of potentially misleading them into thinking they have more privacy than they actually do. In the case of DoH it will also likely inadvertently end up centralising a huge chunk of DNS lookups in to the hands of a few large corporations thanks to it being opt-out rather than opt-in. At least DoT avoids that (and offers server-to-server encryption). Much better for users who want unfettered internet access and privacy to encrypt the whole lot with a VPN and use a resolver that validates DNSSEC. If the chain of resolvers were all DoT enabled that would definitely be a nice extra but hardly essential. Alternatively, if you're in a country with a healthy ISP market (and government you're not afraid of), there's always the option to simply move to a provider that doesn't tamper with and monetise user traffic.
  - tialaramex 7y ago
    > TLS certs still have unique serials In TLS 1.3 everything sent by the server, including its certificate, is encrypted. This is possible because of a re-ordering of considerations. It used to be that the conversation starts like this: Client: "Hi, I want to talk to Server?" Server: "Here's a certificate for Server, which is me" Client: [ "Secret is 123456" encrypted using the Public Key from the certificate for Server ] Server: [ "See, it's me" encrypted using the secret 123456 ] But in TLS 1.3 it starts like this: Client: "Hi, I want to talk to Server and I used ECDHE to pick this number 123" Server: "I used ECDHE and I picked 456..." [ "I am Server, here's a Certificate for Server, and here's a signature proving the conversation we're having right now is with me, Server, which you can verify using the Public Key in that Certificate" encrypted using the secret 987654 ] ECDHE allows Client and Server to agree the secret key 987654 even though the information they publish to agree on it (123 and 456) is public for anyone to see. Its predecessor Diffie Hellman is easier to understand if you never got past high school mathematics, so research that if you've never seen this trick before. You'll notice this is also less round trips (so better performance over high latency links) as well as being more secure and more future-proof.
    - corford 7y ago
      This is very cool. Thanks for the great explanation!

ekimekim 7y ago

This is addressed in TFA: The fact that there are multiple problems and solving any one of them doesn't help much until they're all solved, should not be an excuse to refuse to solve any of them.

im3w1l 7y ago
So you have a "solution" that doesn't really solve the problem, and also create a new privacy problem (now cloudflare has your data too). Hence it's actually a privacy loss.

hunter2_ 7y ago

For some (large, especially) sites, the IP address maps to the entity you're trying to contact. For others (small, especially) sites, the IP address is shared among many entities... not just shared origin hosts but also the massive reverse proxies of the world (Cloudflare, etc.).

zzzcpan 7y ago
There is an actual research on this. More than 90% of alexa's top 1 million websites (more like 95% or so) are uniquely identifiable just by IP addresses you connect to when you visit them. This is not a single IP address per website, but multiple, because websites include subresources with other IP addresses to connect to. On top of that, there is a pressure on CDNs and clouds to make websites stick to specific IP addresses and make them blockable by IP addresses without affecting other customers. So far they have proven to not go against this pressure and even made technical solutions to aid governments to identify websites by IP addresses, in particular by fixing L7 routing layer to block domain fronting (which is important, because ESNI is basically domain fronting, but crappy, and the pressure didn't go anywhere, so there is the same pressure to make sure ESNI doesn't interfere with identification of websites you are visiting).
- wolco 7y ago
  How would they force cloud providers customers to host on an ip? Do you envision restrictig new instances with manual approvals required?
judge2020 7y ago
Also, Cloudflare does give Business and Enterprise customers their own IP addresses (although often rotated) so that these sites work with old non-SNI browsers.

mantap 7y ago

That doesn't work anymore. ISPs are not going to block AWS IP ranges or Azure IP ranges, etc. The cloud killed IP blocking. The pirate bay is supposed to be blocked in UK by court order, but because they use cloudflare it's still accessible and only DNS blocked.

throw0101a 7y ago
> ISPs are not going to block AWS IP ranges or Azure IP ranges, etc. Tell that to China, Iran, Turkey (?), etc.
- ru552 7y ago
  Ok, authoritarian regimes not included
  - throw0101a 7y ago
    > Ok, authoritarian regimes not included And yet this was/is one of the justifications for implementing this. They're not doing it in the EU because (a) there are decent privacy laws, and (b) IP addresses are (IIRC) considered personal information and so Cloudflare DoH would be responsible for keep a whole bunch of data safe. They may not want that responsibility. This seems to (currently) be US-only because of the sucky US privacy laws.
    - mantap 7y ago
      No the justification is to make it harder for non-authoritarian countries to block websites. If China or North Korea want to block the IP range of AWS+Azure+Google that's up to their respective autocrats. Most democratic or even hybrid regimes are not prepared for that level of absolute chaos and consequent protest if half the Internet is shut down. You can only pull that shit in a dictatorship.
gsich 7y ago
Blocking wasn't the point in the post above.