On 2004-11-22 07:57:44 -0500, John Peacock wrote:
> David Nicol wrote:
> ><mode aspect="visionary" mood="frustrated">
> >
> >DNS would work better for this since it has well-defined caching,
> >unlike VRFY, but adding a local cache would also work well,  and
> >nobody wants to muck with custom DNS servers that much
> >
> ></mode>
> 
> I have to say that this is completely daft (IMNSHO).  This is yet another 
> precarious layer to the house of cards that people have made DNS

I won't debate that, but ...

> In addition, using DNS for user validation would make dictionary attacks 
> practical again, since DNS is a public service by default.  Both my 
> implementation of VRFY and my finger server specifically were designed to 
> allow only specified hosts to access the data.  Yes, I know you could run a 
> second authoritative DNS server, but that immediately loses what little 
> benefit to using an existing framework by having to provide parallel 
> services.

You don't need a second authoritative DNS server, just ACLs on the zone
with the email addresses:

zone "_vrfy.example.com" {
    allow-query {
        mx1;
        mx2;
    }
}

in bind. for <[EMAIL PROTECTED]>, an RR for joe._vrfy.example.com would
then be queried.

        hp

-- 
   _  | Peter J. Holzer    | Je h�her der Norden, desto weniger wird
|_|_) | Sysadmin WSR       | �berhaupt gesprochen, also auch kein Dialekt.
| |   | [EMAIL PROTECTED]         | Hallig Gr�de ist fast g�nzlich dialektfrei.
__/   | http://www.hjp.at/ |   -- Hannes Petersen in desd

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