RE: reverse DNS; RE: [Asrg] RMX proposals and Nash Equilibrium

["Eric D. Williams" <eric@infobro.com>]

I think we concur fully (e.g. incremental).

-e

On Monday, May 05, 2003 6:19 PM, Bob Atkinson 
[SMTP:bobatk@Exchange.Microsoft.com] wrote:
> Reverse DNS has two quite important situations in which it does not
> easily (if ever) give appropriate answers for use in spam deterrence.
>
> 1) If I host my own DNS servers, and have no DNS relationship with my
> ISP, then (typically, if not mostly) the rDNS lookup will ultimately go
> to him but have no means by which it can connect to my DNS servers and
> thus give a meaningful response. As a result, the rDNS lookup yields
> answers like
>
> 	dsl-209-123-212-68.myisp.com
>
> rather than something related to the email domains that I actually send
> from.
>
> 2) If, for one of possibly many reasons, I legitimately relay my
> outbound mail through some other domain, then it becomes
> administratively very cumbersome (if not logistically impossible,
> pragmatically speaking) to have the rDNS lookup resolve to something in
> my domain (in addition to the one through which I am relaying, and all
> the others he relays for).
>
> RMX-style proposals, which start their lookup at the domain purportedly
> responsible for a message, don't suffer from these shortcomings.
> (indeed, they can nicely leverage the existing administrative
> infrastructure that I necessarily have to mange my MX records). This is
> an important advantage.
>
> Ultimately, these approaches yield the same information, namely an
> answer to the question: "is this IP address authorized by the admin of
> this domain to transmit mail on behalf of that domain". While the
> spoofing that this prevents is VERY interesting and useful, it is, in
> and of itself, of course not something that will eliminate spam.
> Additional infrastructure is needed above and beyond RMX.
>
> 	Bob
>
>
> -----Original Message-----
> From: asrg-admin@ietf.org [mailto:asrg-admin@ietf.org] On Behalf Of Eric
> D. Williams
> Sent: Saturday, May 03, 2003 6:16 PM
> To: 'Daniel Feenberg'; asrg@ietf.org
> Subject: RE: [Asrg] RMX proposals and Nash Equilibrium
>
> All of these are valid points to argue, but without addressing a
> fundemental
> point (not described in most) RMX proposals from my understanding.  That
> is,
> DNS can also be used to validate an IP reverse map so that not only the
> domain
> is checked but also the IP.  In that case, IMHO, one could argue that an
>
> additional check for IP origination or relay of delivery would mitigate
> the
> concerns.
>
> I could definitely be wrong but that always sticks out to me as a
> mis-understanding of that type of proposed solution/strategy.  I don't
> think
> the forwarder of mail has to be penalized for forwarding if they are
> properly
> registered in the forwarding path (open-relays are another matter in my
> opinion) and are no longer used in the historical context (helping a
> brother/sister system out).

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