[76133] in North American Network Operators' Group
RE: is reverse dns required? (policy question)
daemon@ATHENA.MIT.EDU (cjosephes@ibsys.com)
Thu Dec 2 10:35:41 2004
From: cjosephes@ibsys.com
To: schampeo@hesketh.com, nanog@merit.edu
Date: Thu, 2 Dec 2004 09:33:41 -0600
Errors-To: owner-nanog-outgoing@merit.edu
> Quick example, though: of 6936 patterns currently in my list, if you
> just run a cut on \\ (which catches either '.' or '-' as the
> next char,
> for the most part) you get (matches of 20 or more):
>
> count first left-hand pattern part
> ----- ----------------------------
> 1572 ^[0-9]+
> 206 ^.+
> 200 ^host[0-9]+
> 179 ^host
Exceedingly long list cut....
Just to throw in my own 2 cents: I find it really ironic that we rely on
reverse DNS data that potentially comes from a spammer in order to determine
whether or not someone is a spammer. It probably works for the zombies.
But in the long run, ip based filtering is quicker, since there's no DNS
check and you have a better idea of the size of the netblock you're
filtering.
I'll be a lot happier once the smtp-submission port (587) catches on. It
will make filtering a lot simpler.
