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Re: [DNSOP] DNS cookies and multi-vendor anycast incompatibility

Paul Wouters <paul@nohats.ca> Wed, 20 June 2018 14:10 UTC

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Date: Wed, 20 Jun 2018 10:10:03 -0400
From: Paul Wouters <paul@nohats.ca>
To: Petr Špaček <petr.spacek@nic.cz>
cc: "dnsop@ietf.org WG" <dnsop@ietf.org>, Daniel Salzman <daniel.salzman@nic.cz>
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Subject: Re: [DNSOP] DNS cookies and multi-vendor anycast incompatibility
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On Wed, 20 Jun 2018, Petr Špaček wrote:

> it seems that current specification of DNS cookies in RFC 7873 is not 
> detailed enough to allow deployment of DNS cookies in multi-vendor anycast 
> setup, i.e. a setup where one IP address is backed by multiple DNS servers.
>
> The problem is lack of standardized algorithm to generate server cookie from 
> a shared secret. In practice, even if users manually configure the same 
> shared secret, Knot DNS and BIND will use diffrent algorithm to generate 
> server cookie and as consequence these two cannot reliably back the same IP 
> address and have DNS cookies enabled.
>
> One of root server operators told me that they are not going to enable DNS 
> cookies until it can work with multi-vendor anycast, and I think this is very 
> reasonable position.
>
> So, vendors, would you be willing to standardize on small number of server 
> cookie algorithms to enable multi-vendor deployments?

I think this is a good idea but there are already two examples in RFC
7873 for cookie generation. Is there a problem with those examples, or
is there only a lack of options in the implementation to configure
these? If the latter, than no new IETF work would be needed.

Paul

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