[SURBL-Discuss] Re: Bill Stearns' sa-blacklist available as SURBL: ws.surbl.org

[David B Funk]

On Tue, 20 Apr 2004, Jeff Chan wrote:

> On Tuesday, April 20, 2004, 7:12:25 PM, Scott Truman wrote:
> >  On Tuesday, April 20, 2004, 6:10:30 PM, Bill Landry wrote:
>
> >  > 127.0.0.2 = Spamcop
> >  > 127.0.0.3 = WS List
> >  > 127.0.0.4 = BigEvil List
> >  > 127.0.0.5 = etc...
>
> >  > Same thing multi-test RBLs like AHBL, Sorbs, Blars,
> >  FiveTen, NJABL and
> >  > others do.
>
> > One could even extend that as such (if they don't already):
>
> >  127.0.0.2 = SC List
> >  127.0.0.4 = WS List
> >  127.0.0.8 = BigEvil List
> >  127.0.0.16 = Someother List
> >  etc....
>
> >  Multiple hits for the same lookup could be returned by combining the last octet i.e. a result of 127.0.0.10 would indicate the URI was found in both the SC and BigEvil lists. If one was only
> > interested in what SC found, then one would AND the result with 127.0.0.2
>
> Nice.  We probably will do an "all" list, so this is good to
> think about.
>
> Does anyone have any comments about either approach?  Bill seems
> to indicate there was a precedent in other "combining" RBLs, but
> Scott's suggestion is also clever.

Both two encodings are used by other DSBLs. The first one is an
enumeration (used by Sorbs, NJABL, etc), the second one a bit-field
("set") (used by MAPS RBL+).

The enumeration has the advantage of being simpler and covering
more posibilities but is only single valued. (IE the match is for
only one possible list).

The bit-field has the advantage of being able to represent membership
in multiple lists at the cost of represinting fewer lists (7 as opposed
to 254 possible groups). IE you can say that a particular entry
is in both SC list & WS list.

SA already has functions for picking apart either kind of representation.

Given the nature of the proposed blackist (IE a compilation of different
sources of information), I'd suggest the bit-field format to best handle
the case of a given host being in more than one list.


-- 
Dave Funk                                  University of Iowa
<dbfunk (at) engineering.uiowa.edu>        College of Engineering
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