nanog mailing list archives

Re: best practices for PTR naming and whois (was, sadly, Re: Arrogant RBL list maintainers)


From: Mark Andrews <marka () isc org>
Date: Fri, 11 Dec 2009 03:38:00 +1100


In message <4B211DA6.9000203 () mtcc com>, Michael Thomas writes:
On 12/10/2009 07:54 AM, Steven Champeon wrote:
In a nutshell, if you're not clearly indicating mail sources as mail
sources, don't expect great deliverability. If you're running a Web
hosting shop and don't have rate-limited outbound smarthosts, expect all
your clients' mail to be suspected of being phishing scams. If you run a
corporate network that allows unsecured outbound port 25 via NAT, you
lose. If you run a university network (or part of one) without clearly
distinguishing between server infrastructure and student-use end nodes,
you really might want to rethink that. And if you're a consumer ISP that
allows both static and dynamic assignments or serves both residential
and commercial under the same useless generic naming convention, you are
Making It Harder for the rest of us, which is an automatic upgrade path
to reflexive blocking of all traffic. Oh, and if it's out of your control
or what you consider your responsibility, SWIP it and label it clearly
so we can figure out what it is and decide whether we want it as part
of our view of the Internet. Keep your whois up to date and indicate
if nothing else whether a given block is static or dynamically assigned,
residential or corporate.

I'd say that Mikael Abrahamsson's sentiment (or at least the way I read
it) would be a better start: take a step back and ask what the problem is.
Naming conventions blah, blah, blah all started from the _lack_ of a
standard and trying to educe knowledge from chaos. In other words, a
bunch of hacks. Which doesn't work especially well, especially when
every RBL has its own hack.

If IETF can do something here, which seems plausible, it would be to actually
define the problem and _then_ write a protocol to fit the needs of the
problem. Maybe it's using DNS, maybe it's not. Maybe it uses naming conventions
(ick), probably it does not. But if it were standardized, it would at least
be predictable which the current situation manifestly is not.

To Crocker's point though: if IETF came up with a way to publish your network's
dynamic space (assuming that's The Problem!), would operators do that? Or is
this another case where the energy barrier is too high?

Mike
 
The way to do this is to put other data in the ip6.arpa/in-addr.arpa and
stop trying to infer things from the PTR records.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka () isc org


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