Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended-error-07.txt
Shane Kerr <shane@time-travellers.org> Mon, 26 August 2019 20:34 UTC
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From: Shane Kerr <shane@time-travellers.org>
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Date: Mon, 26 Aug 2019 22:34:03 +0200
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Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended-error-07.txt
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Loganaden & all, On 10/08/2019 07.37, Loganaden Velvindron wrote: > On Sat, Aug 10, 2019 at 9:14 AM <internet-drafts@ietf.org> wrote: >> >> >> A New Internet-Draft is available from the on-line Internet-Drafts directories. >> This draft is a work item of the Domain Name System Operations WG of the IETF. >> >> Title : Extended DNS Errors >> Authors : Warren Kumari >> Evan Hunt >> Roy Arends >> Wes Hardaker >> David C Lawrence >> Filename : draft-ietf-dnsop-extended-error-07.txt >> Pages : 13 >> Date : 2019-08-09 >> >> Abstract: >> This document defines an extensible method to return additional >> information about the cause of DNS errors. Though created primarily >> to extend SERVFAIL to provide additional information about the cause >> of DNS and DNSSEC failures, the Extended DNS Errors option defined in >> this document allows all response types to contain extended error >> information. >> >> > I went to talk to quad9. Here is the reply they sent. > > Fwd: > > 1) I see at least one more model that needs to be supported, which is > how to handle edns extended codes that are generated by a remote > server, i.e. passthrough. Layering multiple forwarding resolvers > behind each other is common, and some way to notify the end user that > the originating message was not generated by the first resolver would > be important. I don't know if there needs to be some way to indicate > how "deep" the error was away from the end user; it seems just two > levels (locally generated or non-locally generated) would be > sufficient with only minor thought on it. > > > Re: 1) This is a good point, but implementation will likely run afoul > of existing standards or else require duplicative response codes or > use of an additional flag in the INFO-CODES section. > Perhaps a new flag type, similar to AA, which can be used to say that > this recursor will return this result reliably/deterministically. > Attempting to provide depth is perhaps unlikely, but flags for > stub/forwarder/recursive/intermediate recursive or a subset of those > might make sense. > Perhaps a non-descript flag such as 'DR' for Deterministic Response. > Obviously INFO-CODES can support many different flags, of which IR > (Intermediate Resolver) or such could be included > at the point of response generation, with the last server providing > actual data in the chain being the one to authoritatively set the > flag, which then must not be modified by further > downstream resolvers in the process of returning the response. Yeah. In principle EDNS0 is hop-by-hop, so getting more information like this doesn't really fit in the protocol. Maybe EDNS1 should include information indicating which hop is responsible for any particular bit of EDNS? 😊 > 3) Really, I'd like to see a definition of some of the EXTRA TEXT > strings here, since that will be almost immediately an issue that > would need to be sorted out before this could be useful. There have > been some discussions (sorry, don't know if it's a draft or just > talking) about browsers consuming "extra" data in DNS responses that > can do a number of things. As an example that is important to Quad9 > (or any blocking-based DNS service) it might be the case that upon > receiving a request for a "blocked" qname/qtype, we would hand back a > forged answer that leads to a splash page as the default result. > However, if the request was made from a resolver stack that had the > EDNS extensions, we might include the "real" result in the EXTRA TEXT > field, as well as a URL that points the user to an explanation of why > that particular qname/qtype was blocked. Or we might add a risk > factor, or type of risk ("risk=100, risktype=phishing") or the like. > This allows a single query to be digestable by "dumb" stacks that we > want to have do the most safe thing, but also allow "smart" resolver > stacks to present a set of options to the end user. > > Re: 3) Seems reasonable. I think this sort of structured information can and probably should be included today using the private EDNS option space. Rather than embedding parsable information in the EDE equivalent of a TXT record, why not just add a new option with this data, which can be defined and structured? Cheers, -- Shane
- [DNSOP] I-D Action: draft-ietf-dnsop-extended-err… internet-drafts
- Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended… Loganaden Velvindron
- Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended… Shane Kerr
- Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended… Wes Hardaker
- Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended… Loganaden Velvindron
- Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended… Wes Hardaker