On Thu, 9 Oct 1997, Greg A. Woods wrote:
> [ On Wed, October 8, 1997 at 23:07:38 (-0700), tom@??? wrote: ]
> > Subject: Re: Spam Filter
> >
> > I don't particularly like TCP wrappers, especially big ones, because of
> > the constant re-parsing of the same config file. But I guess it could be
> > converted for Exim's "sender_net_reject".
>
> TCP Wrappers are a whole lot easier to implement (trivial really) than
> trying to get BGP running, esp. if you don't already have BGP running,
> and esp. if you're on the end of a very narrow pipe!
Larger sites will have it for other reasons. Since it is there, you
might as well use it.
> TCP Wrappers are nice and general too -- you can go nearly instantly
> from rejecting just SMTP connections to rejecting every type of
> connection they might think to bomb you with. Not quite as nice as an
Not really an issue for larger sites, because I don't think large sites
would run non-dedicated mail servers.
> IP filter in your router or firewall, but given the nature of SMTP
The router will check each packet if it matches a filter, but if you do
it at the application protocol level, you only need to check at session
startup. Depends which is more powerful, your mail server or your router,
and what kind of "pressure" is being applied.
> they're a lot nicer on the poor remote user who might not know he's
> sharing bandwidth with known perpetrators of e-mail abuse. THis way the
> mailer can send back a nice 500 message explaining that his connection
> has been administratively refused for local policy reasons.
See Exim sender_net_reject
> --
> Greg A. Woods
>
> +1 416 443-1734 VE3TCP <gwoods@???> <robohack!woods>
> Planix, Inc. <woods@???>; Secrets of the Weird <woods@???>
>
>
Tom
Systems Support
SDF
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