Maintained by: NLnet Labs

[Unbound-users] allowing cache queries but not doing recursion for "foreign" networks

Greg A. Woods; Planix, Inc.
Sun Feb 15 03:49:36 CET 2009


On 14-Feb-2009, at 3:59 PM, I wrote:
>   I prefer to leave the public data in the cache publicly accessible  
> even if that also gives the bad guys a bit more of an edge  
> (debugging is still more important to me).  However without per-zone  
> ACLs that won't be possible.

A first step towards what I really would like best I think would be  
the ability to control whether or not recursion is allowed for queries  
coming from specified addresses while still allowing answers to be  
given from the cache.  Such answers would have the recursion allowed  
bit turned off too of course.

That way I could configure my cache servers such that recursion would  
only be done for my own known networks, and I would still allow any  
other site to query the cache for debugging purposes.

Perhaps the next step would be to never return any records for any  
domain names containing RFC 1918 data (A RRs or PTR RRs or any other  
RRs associated with RRs containing A or PTR RRs referring to RFC 1918  
data) whenever recursion is not allowed for the query.  Some private  
data might still leak with such a rule, but never enough to give away  
internal network topology.  Alternately maybe all RRs returned in  
answer to queries sent to private addresses should be flagged to  
remain private.

I.e. anyone can see anything in my cache except my private data, but  
they wouldn't be able to force me to try to load anything into my  
cache.  Only clients sending queries from locally "trusted" networks  
would get full recursion and caching services.

Personally I also think this should be the only way any DNS cache  
should work -- i.e. it should be the only mode of operation.  Public  
(DNS) data should remain public no matter where it is stored.

Does this all make sense to anyone?  Does anyone else want such  
functionality too?

-- 
					Greg A. Woods; Planix, Inc.
					<woods at planix.ca>

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