On Wed, Aug 29, 2001 at 06:07:21PM -0600, Charles Cazabon wrote:
> Nicolas Noble <[EMAIL PROTECTED]> wrote:
> >
> > If somebody use a wrong local user during an SMTP connection to qmail,
> > qmail won't say a "550 unknow user" but will later send a mail back to the
> > sender. This is very annoying because anybody can use my smtp server to do
> > mailbombing to somebody else like:
> [snip]
>
> Well known attack against any MTA that does/can not do local-part
> verification during the initial SMTP conversation.
For example, any sendmail machine that is being secondary MX for a
domain (just to point out it's not qmail-specific).
> Nobody uses this attack -- for each message they inject, they can
> provoke at most one bounce. It's quicker and easier for them to exploit
> an open relay and amplify their attack a hundredfold.
Correct, open relays allow easy and massive amplification.
Greetz, Peter
--
Monopoly http://www.dataloss.nl/monopoly.html
