Re: Filtering spam from dialup accounts

[Sebastian Taralunga <]

On Wed, 13 May 1998, Scott A. Marlin wrote:

> laitinen@localhost wrote:
> > 
> > Hi!
> > 
> > Good that you're taking action ;-)
> > 
> > First of all, if the spammer uses your smtp server (or not), you should turn
> > your mail relay function off, ie. you shouldn't relay mail that just passes
> > your system and doesn't originate from your domain and isn't addressed to your
> > domain. Otherwise anybody could abuse your system, and it is only a matter of
> > time that somebody does it.
> > 
> 
> I think you have misunderstood the problem. Our mail servers are using
> anti-spam techniques like those you describe.
> 
> In this precise case, the "customer" is logging into a diap-up (modem)
> account and is using his *own* mail server to spam from his home or
> office. What I am looking for are filtering techniques like "no SMTP
> packets can leave InterNeXT if they are from a certain range of IP
> addresses" - I was thinking of a solution on a BGP level.
> 
> Another way of solving the problem would be for *all* other SMTP servers
> to reject mail coming from unresolved hosts. That would help get the
> reverse ARPA up to date. I may just start responding to spam complaints
> in this manner :-)
> 
> > Then you might want to consider legal action against this spammer, if possible.
> 
> This will certainly be considered if we get our hands on him. It is too
> easy to get a POP account these days : no proof of identity is needed in
> France.
> 
> In any case, thank you for your time.

Try using a Linux server with ipfwadm as a filter for all
your outgoing traffic. You can tell ipfwadm to filter all
out-going packets on port 25. 

Ipfwadm is available from 
ftp://ftp.xos.nl/pub/linux/ipfwadm/ipfwadm-1.2.tar.gz
see for reference http://www.xos.nl. 

Best Regards, 

Sebastian 
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