[SHAME] Spam Rats

Fri Jan 11 12:32:30 UTC 2013

John Levine <johnl at iecc.com> wrote:

> >*.4.4.3.0.5.a.0.0.8.b.d.0.1.0.0.2.ip6.arpa. PTR a.node.on.vlan344.namn.se.
> >...will work just fine, for instance.
>
> Since there is no AAAA record for a.node.on.vlan344.namn.se., this
> won't work fine in any rDNS check I'm aware of.

I believe it's relatively common for mail servers to just check the
existence of a PTR record without any further sanity checking, e.g.
Postfix's reject_unknown_reverse_client_hostname smtpd_client_restrictions
option.

Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
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