Petr, sorry for delayed response, > On Feb 11, 2015, at 11:24 AM, Petr Spacek <pspa...@redhat.com> wrote: > > Hello dnsop, > > draft-ietf-dnsop-dnssec-roadblock-avoidance is a nice idea in general but > current version of "Roadblock Avoidance", section 5, version 01 has a > significant drawback: > > Else if the resolver is labeled "Not a DNS Resolver" or > "Non-DNSSEC capable" > > Mark it as unusable and try next resolver > > This effectively cuts off the client from local DNS view, which can > effectively mean that internal resources on the network will be unavailable. > You are correct we ignore split-DNS completely and that is on purpose. It is unfortunately badly/not defined. But in your case there is in many cases simple solution “when running SPLIT-DNS make sure internal DNSSEC resolvers are DNSSEC capable and sign inside and outside if there is overlap in names.”
> On public networks it may be perfectly fine to sacrifice local names to get > DNSSEC validation. > > However, on internal networks it is a big problem for practical usability of > the system. I personally experienced this when using dnssec-trigger on > networks where DHCP does not send complete list of local DNS domains. (Also, I > have to say that the fact that dnssec-trigger disables DNSSEC validation for > list of domains supplied DHCP effectively takes all the security away …) This is side effect of the badly specified nature of SPLIT-DNS, > > Generally my concern is about practical usability of the proposed solution: > Imagine that I'm road-warrior/consultant who is traveling all the time and is > working for different companies. When I arrive to a customer I should not need > to spend time fiddling with network configuration to get connected to local > network before I can start working on customer's problem. > > > Few guys in Red Hat proposed "hacky but almost-reliable automatic" way how to > improve usability without sacrificing security. > > > Disclaimer > ========== > Method described below is covered by US patent application named "USING DOMAIN > NAME SYSTEM SECURITY EXTENSIONS IN A MIXED-MODE ENVIRONMENT". > > See Red Hat, Inc. Statement of Position and Our Promise on Software Patents: > http://www.redhat.com/legal/patent_policy.html > > I reject the below text as I do not want any IPR on anything in this informational document. Olafur > The Hack > ======== > Fundamental assumption: > Internal & external DNS view are both signed with the same keys or both > unsigned. This assumption allows the method to work without explicit > configuration on every client and removes dependency on reliable/secure > network-detection logic. > > > The main idea can re-phrased as amendment to section 5 of the draft: > > The general fallback approach can be described by the following > sequence: > > If the resolver is labeled as "Validator" or "DNSSEC aware" > Send query through this resolver and perform local > validation on the results. > > If validation fails, try the next resolver > > Else if the resolver is labeled "Not a DNS Resolver" or > "Non-DNSSEC capable" > Mark it as unusable and try next resolver > > --- amended text begins here --- > > Else if no more resolvers are configured and if direct queries > are supported > 1. Try iterating from Root > > 2. If the answer is SECURE/BOGUS > Return the result of iteration. > > 3. If the answer is INSECURE > Re-query "Non-DNSSEC capable" servers and get answer > from "Non-DNSSEC capable" servers. > Set AD bit to 0 before returning the answer to client. > > Else return a useful error code > > > This method covers DNS split-views with internal unsigned views pretty > nicely as long as the fundamental assumption holds. (Naturally it works only > for cases where fallback to iteration is possible.) > > We wanted to write Unbound module for this but it is harder than it seems. > (Proof-of-concept with stand-alone DNS proxy works fine, we have problem with > Unbound module architecture - not with the described method.) > > Feel free to incorporate the idea to the draft if you wish. > > -- > Petr Spacek @ Red Hat > > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www.ietf.org/mailman/listinfo/dnsop _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
