Re: comcast ipv6 PTR

[Barry Shein <bzs () world std com>]

On October 9, 2013 at 20:18 cma () cmadams net (Chris Adams) wrote:
> Once upon a time, Barry Shein <bzs () 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.

> I only see a use for reverse DNS for router interfaces (for useful
> traceroute info) and servers (and only really SMTP servers).  Most of
> the rest is fluff, often out-of-date, uselessly auto-generated, etc.

It's pretty amazing how much spam comes from hosts with names a lot
like ns1.example.com, their name servers. Not sure why they're so
easily abused but maybe it doesn't occur to them to lock down MTAs on
their name servers.

-- 
        -Barry Shein

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