Re: [Sidrops] nlnet rp and rsync

[Randy Bush <[e-mail]>]

turning a private discussion public, with consent of course

it turns out that, to quote tim

> Routinator has had support for RRDP since version 0.6.0, released in
> September 2019.
> 
> If it finds an RRDP SIA and successfully synchronizes the publication
> point once, it will whitelist the RRDP SIA URI and it will no longer
> fall back to rsync where this URI occurs on CA certificates. As long
> as the synchronization has not been successful it will fall back to
> rsync.

to which i then said

> that seem a potential violation of spec.  if the PP RRDP service then
> fails, it really MUST fall back to the mandatory to implement rsync.
> 
>> As long as the synchronization has not been successful it will fall
>> back to rsync.
> 
> s/As long as/If/

to which martin said

> Can you point me to where it says that? Section 3.4.5 of RFC 8182 is
> pretty indifferent about it.

to which i said

> among other places, 6481 s3
> 
>      *  The publication repository MUST be available using rsync
>         [RFC5781] [RSYNC].  Support of additional retrieval mechanisms
>         is the choice of the repository operator.  The supported
>         retrieval mechanisms MUST be consistent with the accessMethod
>         element value(s) specified in the SIA of the associated CA or
>         EE certificate.

to which martin responded

> This talks about what the publication point has to offer, not what a
> cache has to use. In particular, it says that the publication point
> musn’t advertise RRDP unless it actually offers RRDP. Which means that
> as a cache I can rely on RRDP being available.
> 
> Forcing a cache to use rsync instead of RRDP is a downgrade attack and
> should be handled accordingly.

at which point i said it is time to take this to the wg.  so here we go.

imiho, 6481 makes it very clear that rsync is currently the mandatory to
implement protocol (yes i am a coauthor of a draft trying to eventially
change that).  i contend that this is MTI by both the publisher and by
the client.

randy