comcast ipv6 PTR

Mon Oct 14 23:28:16 UTC 2013

On 10/10/13 1:09 AM, "Barry Shein" <bzs at world.std.com> wrote:

>
>On October 9, 2013 at 20:18 cma at cmadams.net (Chris Adams) wrote:
> > Once upon a time, Barry Shein <bzs at world.std.com> said:
> > > It's very useful for blocking spammers and other miscreants -- no
> > > reason at all to accept SMTP connections from troublesome
> > > *.rev.domain.net at all, no matter what the preceding NNN-NNN-NNN-NNN
> > > is.
> > 
> > If you are going to block like that, just block anybody without valid
> > reverse DNS.  If you don't trust provider foo.net to police their
>users,
> > why trust them to put valid and consistent xx-xx-xx-xx.dyn.foo.net
> > reverse?
>
>Because they do, they just do. This isn't a math proof, it's mostly
>social engineering. The providers aren't trying to fool anyone, in
>general, it's just that clients and websites get botted.

Except the point of this thread is that they don't.

Is it easier to block inbound mail from hosts with certain high-level
domain
names in their PTRs than to block ranges of IP(v6) addresses?  Easier for
whom?

Lee