[members-discuss] New (silent) reverse dns checks

Dear Jonas,

We have denied reverse DNS delegation to open recursive resolvers for 
over a decade now. There has not been any recent change to our DNS check 
software or policy.

Open recursive resolvers (as opposed to managed public resolvers like 
Google or Cloudflare DNS) are generally considered to be a security 
risk. They are vulnerable to cache poisoning or may be used to launch 
DNS response amplification attacks against other servers.

Almost all cases of open recursive resolvers are due to misconfiguration 
of a name server, and users are usually not aware of the security risks. 
Our reverse DNS checks help users to improve their configuration and 
security practices, and generally contribute to a safer Internet.

We are not alone in enforcing this check. IANA does the same for 
delegations to name servers of ccTLDs, for example.

If you feel this check is too stringent, we invite you to start a 
discussion in the RIPE DNS Working Group. We will be happy to adjust our 
policy for reverse DNS checks based on input from the working group.

Regards

Anand Buddhdev
Senior System Engineer
RIPE NCC


On 2019-06-07 12:20, Jonas Frey wrote:
> Hi all,
> 
> we just found out that RIPE seems to have silently integrated new
> checks for reverse delegation of zones.
> Its no longer possible to add or even change a zone if the nameservers
> used by them are open recursors. The update will fail.
> Yes - open recursors are (sometimes) bad. But there are legitimate
> reasons to run them (freedom of speech, filtered resources etc). Once
> properly configured (i.e. querys rate limited) they wont pose a threat.
> 
> I wasnt able to find any information on when this was implemented or if
> this was even voted for (please someone supply me with links if
> possible).
> 
> I dont know of any NIC/registrar that will deny the creation/update of
> a domain name if the nameservers are recursors. I know that some will
> warn but none will refuse it. Please fix me if there are some which
> will indeed deny.
> 
> Of course i have created a ticket about this but it all went like "fix
> the dns or we wont delegate".
> 
> So basically this is about 2 things: silently changing checks (if it
> was indeed silent) and if those checks are really usefull or should
> rather be dropped/changed to warnings.
> 
> 
> Regards,
> Jonas
> 
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