Re: [DNSOP] New Version Notification for draft-bellis-dnsop-xpf-00.txt

"Peter van Dijk" <> Fri, 10 February 2017 12:52 UTC

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From: Peter van Dijk <>
Date: Fri, 10 Feb 2017 13:52:16 +0100
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Subject: Re: [DNSOP] New Version Notification for draft-bellis-dnsop-xpf-00.txt
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Hello Ray,

On 6 Jan 2017, at 23:02, Ray Bellis wrote:

> On 06/01/2017 18:43, Wessels, Duane wrote:
>> The idea of "X-Forwarded-For" for DNS makes me nervous, but it is
>> probably inevitable.
>> It is of course quite similar to EDNS client subnet, except that
>> there is no masking and the client cannot opt-out.  Might be worth
>> saying in your document why EDNS client subnet wouldn't work for this
>> purpose.
> I believe that dnsdist / PowerDNS is already (ab)using the ECS option
> for this purpose.
> The intent in part is to provide a separate option so that "real" ECS
> can pass unhindered.  [ not that I think ECS is a good idea, but some
> folks want it, c'est la vie ]

Indeed, dnsdist uses ECS to pass the actual client IP to the real 
backend DNS server. And indeed, this gets confusing when there is also 
‘real’ ECS. So thank you for writing this draft, it will be very 

However, both in ECS, and now in XPF, we do not get client’s port 
number. With increasing CGNAT deployment, this makes it impossible to 
distinguish clients once a request has passed through a proxy, like 
dnsdist or a TLS frontend.

Can you please consider adding a port number field?

Kind regards,
Peter van Dijk