OpenBSD's spamd.

[JoaoBR]

On Tuesday 19 December 2006 15:46, Christopher Hilton wrote:
> JoaoBR wrote:
> > why the spam daemon should introduce an artificial delay
> > (tarpit) if this can be done already before like Oliver
> > said, it would only eat up and slow down threads  between
> > both daemons (smtp + spamd) and overall spamd doesn't even
> > talk directly to the remote smtp
>
> Spamd does talk to the remote smtp. It does this until it determines
> that the remote smtp is RFC compliant in the area of retrying mail. On
> the first delivery attempt it sets up a time window for the delivery
> tuple: (server, sender, recipient). If it receives another delivery
> attempt within this time window it modifies a PF table which allows
> further delivery attempts to bypass spamd and talk directly to your
> actual smtp daemon. Without this entry remote smtp daemons talk to your
> spamd.
>
> The tarpitting features of spamd are handy. Bob Beck, the author IIRC,
> watched connections to his spamd and noticed that the when tarpitted,
> the spammers and only the spammers were disconnecting from his machine
> and giving up on delivering the spam at all after ever shorter
> intervals. When the spammers got down to 3 seconds of tarpitting before
> they disconnected he added a feature to spamd that allows you to tarpit
> all inbound smtp connections for a configurable period of time (default:
> 10 seconds).
>
> So imagine being able to eliminate a portion of the spam that you get.
> This is spam that never gets to your MTA. It doesn't cost you CPU cycles
> in SpamAssassin and procmail or clamav. And all you pay is three seconds
> of the your firewall's time.
>

opss, so your spamd must be ports/mail/spamd then, thank's for clarification

I dont know if it is a good solution even if it works. I am completly 
satisfied using sendmails ClientRate and greeting delay features and I do not 
need an additional software to take care of.


-- 

João







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