On Jan 9, 2017, at 10:14 AM, Paul Wouters <p...@nohats.ca> wrote:
> Apple is getting ready to drop port 80 support. unsigned/unencrypted
> transports are dying. I hope we are moving to a word where DNS without
> DNSSEC will also be seen as bad. So yes, I am assuming in the future,
> attackers will have to sign DNS and that domains without DNSSEC are seen
> as "rogue domains that don't have clear audit trails".

It remains the case that most service providers at present appear to believe 
that PKI is enough, and they don't think DNSSEC is worth the trouble.   Like 
you, I look forward to the day when this is no longer true, although I don't 
look forward to the attack that changes peoples' minds about this.

>> I think this is actually not true: why is a DS record any more of an audit 
>> train than an NS record?
> 
> Because it proves ownership of the domain. My nohats.ca DS record cannot
> be modified by the UK ISPs forced to filter my domain. But they can
> spoof NS records. See the recent discovery that Heathrow Airport runs a
> MITM TLS server on torproject.org. Do we want them to run RPZ where they
> can disappear torproject.org alltogether? No. Do we want them to run RPZ
> to prevent travelers from getting malware installed? Yes.

We are talking at cross purposes.   We agree that the DS record proves 
ownership of the zone.   But it doesn't provide any more of an audit trail in 
terms of zone setup than does an NS record.   In terms of accurately 
identifying who set up the zone, it is completely useless.

>> Your point here, that in order for RPZ to function in the presence of 
>> widespread DNSSEC signing, there has to be some mechanism for authenticating 
>> RPZ answers _as_ RPZ answers, doesn't seem clearly true.   It
>> may be perfectly functional for RPZ answers to look like an attack.   But 
>> it's certainly worth considering, and has been talked about earlier in this 
>> thread.   The question is, does it make sense to add code
>> to the validating resolver to detect and validate an RPZ block, so the user 
>> can be informed that a block occurred, and who did it?   Would people 
>> actually code this up?   Would it be better or worse?
> 
> To me that is quite obvious "yes". If we allow the DNS protocol to
> randomly rewrite DNS, then why _do_ we have DNSSEC?

Again, not the point I was making.   Of course we want the resolver to do 
validation.   The question is, do we want the resolver to have code in it to 
validate who did the RPZ block.   I think this would be a really bad idea, and 
would be seriously damaging to human rights.

> Excellent! It means if the RPZ/DNS provider screws up, they are
> accountable. And they will properly maintain such systems that
> are golden opportunity for hackers to compromise. Also, the
> danger you are describing "I can make an attack look like protection to
> the end user" is exactly what the current RPZ spec already allows!
> I guess you really meant to say "a compromised RPZ system can unblock
> a malicious and previously blocked side". Well yes. You are describing
> a weakness, not a strength, of the RPZ solution.

You are thinking like a IETF geek.   The average end user will know nothing of 
this.   To them, it will simply be the case that their computer says "this is a 
malware site."   They will not see the audit trail.   It doesn't matter if the 
ACLU can detect the attack: they could have detected the attack without the 
signature, and most likely had a clear idea of who did it.

What matters is that we have no provided a way for malicious site operators to 
lie to end users, who will not be able to detect the lie.  To be clear, the lie 
is "I am authorized to block zones on your behalf."

> Just blocking the domain is "too much". And in my view that _is_ the
> human rights issue.

We disagree here.   I have seen way too many people screwed over by malware to 
think that preserving a perfect uncensored view of the DNS is more important 
than blocking malware.   As long as we can tell that we have been given a 
filtered response, I think we have the best possible compromise, and if sites 
are not willing to put in the effort to sign their zones, that is their problem.

> If we change this discussion and replace DNS and DNSSEC with BGP and
> RPKI, would you still think it is fine to allow random parties to
> change BGP announcements in a world of secure BGP so that users can
> be prevented to go to certain IP ranges?

If that IP range is being operated by a malware site or for example is going to 
redirect all of my traffic through a country that is sniffing my packets for 
intelligence purposes, then yes, it should be possible for the infrastructure 
to prevent the broken route from being installed, regardless of whether or not 
it has been signed.   This is the distinction between authentication and 
authorization that we all know so well: just because something is _authentic_ 
does not mean that it is authorized.

Taking that very clear distinction and turning it political is not helping 
anyone.

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