On Dec 9, 2008, at 2:42 PM, Keith Moore wrote:
when the reputation is based on something (like an address or
address block) that isn't sufficiently fine-grained to reliably
distinguish spam from ham, as compared to a site filter which has
access to more criteria and can use the larger set of criteria to
filter more accurately.
Email systems resources must be defended when confronting millions of
compromised systems and infiltrated providers slow at removing abusive
accounts. Resources are best preserved when acceptance is decided
prior to the exchange of message data. Mapping regions known to host
compromised systems or having been frequently hijacked is typically
done by IP address. As Ned mentioned, some systems block ranges that
span across announced routes. Although there is no reason for this,
the growing size of the problem and the address space requires
negative assessments be done by CIDR.
Rather than depending upon knowing the location of specific abusive
sources, the Internet needs a registry of legitimate sources which
includes contacts and IP address ranges. Such a list should reduce
the scale of the problem, and allow safer exclusions. Normal defenses
using Turing tests fail as the state of the art advances. Even if
there was a registry, what egalitarian identifier can be used to
defend the registration process? Receipt of text messages or faxes?
Postal mail? What can replace the typical Turing test?
-Doug
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