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To: "Jonathan M. Bresler" <jmb@FreeBSD.ORG>
cc: brian@Awfulhak.org (Brian Somers), kuku@gilberto.physik.RWTH-Aachen.DE,
        dwhite@resnet.uoregon.edu, freebsd-questions@freefall.FreeBSD.org
Subject: Re: /etc/mail - anti spam measures 
In-reply-to: Your message of "Thu, 04 Dec 1997 17:59:46 PST."
             <199712050159.RAA26466@hub.freebsd.org> 
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Date: Fri, 23 Jan 1998 04:09:32 +0000
From: Brian Somers <brian@Awfulhak.org>
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[following up from a month and a half ago - that O'Reilly book is thick]

> Brian Somers wrote:
> > 
> > I've attached my version - altered to deal with machine names too.  
> 
> 	on further reflection, no reason to limit this to 
> 	three part hostnames.
> 
> > # called with host.tld and IP address of connecting host.
> > # ip address must NOT be in the "denyip" database
> > Scheck_relay
> > R$* $| [$+		$1 $| $2			should not be needed
> > R$* $| $+]		$1 $| $2			same (bat 2nd ed p510)
> > R$* $| $*		$: $1 $| $(denyip $2 $)
> > R$* $| $*.REJECT	$#error $: 521 blocked. contact postmaster@FreeBSD.ORG ($2)
> > # host must *not* be in the "spamsites" database
> > 
> > # jmb suggests for hosts as well as domains:
> > R$+.$+.$+ $| $*		$: $(spamsites $1.$2.$3 $) $1.$2.$3 $| $4
> 
> 	replcae the rule above with the rulse below:
> 
> R$+.$+.$* $| $*			$(spamsites $1.$2.$3 $) $1.$2 $| $4
> 
> 	this will iterate, allowing you to check for
> 
> 	host.foo.bar.baz.com
> 	foo.bar.baz.com
> 	bar.baz.com
> 	baz.com

Well, now I know a little more about sendmail, I figure that this 
doesn't quite work.  If I feed this rule `a.b.c $| 1.2.3.4', I'll get

in:  a.b.c $| 1.2.3.4
out: a.b.c a.b $| 1.2.3.4
in:  a.b.c a.b $| 1.2.3.4
out: a.b.c a.b a.b $| 1.2.3.4

etc.  Your rule seems to assume that $( ... $) will eat the string if 
it doesn't match....

Perhaps, what we really want is:

# host must *not* be in the "spamsites" database
R$* $| $*                       $: <$1> <$1 $| $2>
R<$+.$+> $* <$+>                <$2> $| $(spamsites $1 $2 $) $3 <$4>
R<$*> $* $| $*.REJECT $*        <$1> $3.REJECT $4
R<$*> $*.REJECT $* <$*$|$*>     $#error $: 521 $4: $2
R<$*> $* <$+>                   $3

Here, we grab the text from spamsites.db and display it after the 
failed host/domain name :-)

> > #jmb also suggests these two:
> > R$+.$+.$+		$: $(spamsites $1.$2.$3 $) $1.$2.$3
> 
> 	do the same here.

And assuming a "user@domain" input,

# host must *not* be in the "spamsites" database
R$* @ $*                        $: <$2> <$1 @ $2>
R<$+.$+> $* <$+>                <$2> $| $(spamsites $1 $2 $) $3 <$4>
R<$*> $* $| $*.REJECT $*        <$1> $3.REJECT $4
R<$*> $*.REJECT $* <$*@$*>      $#error $: 521 $5: $2
R<$*> $* <$+>                   $3

> jmb

I'd like to commit this to src/etc/mail/sendmail.cf.additions.  Does 
this make sense ?

Cheers.

-- 
Brian <brian@Awfulhak.org>, <brian@FreeBSD.org>, <brian@OpenBSD.org>
      <http://www.Awfulhak.org>
Don't _EVER_ lose your sense of humour....