On Tue, Oct 14, 2003 at 05:48:27PM -0400, Eric S. Raymond wrote:
| Justin Mason <jm(_at_)jmason(_dot_)org>:
| > A DNSBL of "spammer domains".
|
| Wouldn't this just replicate the known problems with blocklists?
SPF was always intended to operate together with some sort of RHSBL-type
database. After all, spammers can publish SPF records too.
SPF tells you the domain is validated; then an RHSBL tells you if the
domain is good or evil. See the bottom of
http://www.sdsc.edu/~jeff/spam/cbc.html
Today RHSBLs have two response types; UNKNOWN and EVIL. A reputation
scheme would add more response types:
UNKNOWN vs KNOWN
RATING: number from -100 to 100
REPORT-SIZE: xx
BEEN-AROUND-SINCE: date
Other response types have been suggested:
ACCOUNTABILITY-LEVEL: whether registrar stores some kind of real-world ID, etc
AOL, Hotmail, Yahoo, Earthlink etc get a very good sample of the total
Internet mailstream. They would be a good source of reputation data.
ISPs aside, schemes like Vipul's Razor collect a tremendous amount of
data about incoming domains. Vipul suggested that he could modify the
Razor client to indicate whether the domain had been SPF-verified; if
so, the reputation scheme would acquire another datapoint.
But this sort of centralized reputation scheme is merely the first thing
that came to mind.
I am sure many more devilishly clever schemes will emerge from the P2P world.
For example, small ISPs can greylist or hold-for-review messages that
meet a spam profile of not coming from a previously whitelisted sender.
If a content filter decides the message looks like spam, the ISP can
forward that decision to a local reputation hub; that hub, once it sees
decisions from enough members, can submit the decision into an
internet-wide RHSBL. Think of it as a distributed hierarchy like the
DNS, only information flows both ways.
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