Re: fixing insecure email infrastructure (was: Re: [eweek article]

[Mark Andrews <Mark_Andrews () isc org>]

> On Fri, Jan 14, 2005 at 10:05:05AM +1100, Mark Andrews wrote:
> > > What is wrong with MTAMARK?
> >     As currently described it doesn't fit well with RFC 2317
> >     style delegations.  They would need to be converted to use
> >     DNAME instead of CNAME which requires all the delegating
> >     servers to be upgraded to support DNAME.
>
> How many legit mailservers get their revDNS from RFC 2317 style
> delegations?

        Lots.  I'm sure that there are lots of ISPs/IAPs on NANOG
        that do RFC 2317 style delegations for their customers.
        Every one of them would need to upgrade their servers to
        support DNAME.  Their clients would also need to upgrade
        their servers to support DNAME as they should be stealth
        servers of the parent zone, to allow local lookups to work
        when the external link is down.

        If you hace a RFC 2317 style delegation then you are almost
        certainly doing your own mail support in addition to your own
        DNS support.

> Marking hosts "MTA=no" is an addon for an explicit block.
>
> I'd assume most ISPs cannot simply mark their revDNS with "MTA=no"
> without changing contracts, but even adding "MTA=yes" would be of
> a lot of help.
>
> And it is really easy and doesn't have any negative side effects ;-)
>
>       \Maex
>
> -- 
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--
Mark Andrews, ISC
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PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews () isc org