comcast ipv6 PTR
Barry Shein
bzs at world.std.com
Thu Oct 10 05:09:39 UTC 2013
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.
> 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 the rest is fluff, often out-of-date, uselessly auto-generated, etc.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
The World | bzs at TheWorld.com | http://www.TheWorld.com
Purveyors to the Trade | Voice: 800-THE-WRLD | Dial-Up: US, PR, Canada
Software Tool & Die | Public Access Internet | SINCE 1989 *oo*
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