rpki vs. secure dns?

Shane Amante shane at castlepoint.net
Wed May 30 04:24:28 UTC 2012


On May 29, 2012, at 8:44 PM, Paul Vixie wrote:
> On 2012-05-29 5:37 PM, Richard Barnes wrote:
>>>> I agree with the person higher up the thread that ROVER seems like
>>>> just another distribution mechanism for what is essentially RPKI data.
> noting, that up-thread person also said "i havn't studied this in detail
> so i'm probably wrong."
>>> But does that distribution method easily allow you to get the full set of available data?
>>> From what little I know, it seems to me that ROVER is optimized for
>> point queries, rather than bulk data access.  Which is the opposite of
>> making it easy to get full data :)
> that's close to the problem but it is not the problem.
> RPKI is a catalogue. it's possible to fetch all of the data you could
> need, before starting what's basically the "batch job" of computing the
> filters you will use at BGP-reception-time to either accept or ignore an
> incoming route. if your "fetch and recompute" steps don't work, then
> you'll have to continue filtering using stale data. if that data becomes
> too stale you're likely to have to turn off the filtering until you can
> resynchronize.
> ROVER is not a catalogue. it's impossible to know what data you could
> need to precompute any route filters, and it's impossible to know what
> 'all possible rover data' is -- in fact that would be a nonsequitur. you
> could i suppose query for every possible netblock (of every possible
> size) but that's an awful lot of queries and you'd have to do it every
> day in order to see new stuff or to know when to forget old stuff.
> the problem is in time domain bounding of data validity and data
> reachability. ROVER expects you to be able to query for the information
> about a route at the time you receive that route. that's point-in-time
> validity and reachability, which you might not have depending on where
> the DNS servers are and what order you're receiving routes in. RPKI+ROA
> expects you to have periodic but complete access to a catalogue, and
> then your future use of the data you fetched has only the risk of
> staleness or invalidity, but never reachability.
> as others have stated, there is no reference collection of bad ideas.
> otherwise we would have written this one up in 1996 when a couple of dns
> people looked at the routing system and said 'hey what about something
> like [ROVER]?' and the routing people explained in detail why it
> wouldn't work.

Just one correction to the above.  As pointed out in Section 4 of draft-gersch-grow-revdns-bgp-00 "near-real-time route origin verification" is merely one instantiation of the "ROVER concept".  Please refer to that section for other potential uses of such published data.

I would also ask people to expand their minds beyond the "it must have a (near-)real-time mechanism" directly coupled to the Control Plane" for a variety of reasons.  Such a tight coupling of /any/ two systems inevitably, and unfortunately, will only fail at scale in ways that likely would never have been predicted a priori[1] -- unfortunately, you only learn this lesson afterward.  Question is: how quickly can you detect and react to unwind the specific problem w/out having to turn it off completely, (i.e.: "shields down")?  Alternatively, is it more prudent to engineer some 'sanity' safeguards, (i.e.: back away from the 'real-time' aspect), to avoid this from happening at all or at least extremely rarely?


[1] FWIW, Dave Meyer has been doing some thinking about "complexity" for a while now, drawing analogies from outside of networking/computing, and has some fascinating insight.  I'm sure if there's enough interest, he'd be willing to discuss it.  Who knows, we may even learn something.  :-)

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