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Date:      26 Apr 2002 06:33:28 -0400
From:      Dan Pelleg <dpelleg+bsd@cs.cmu.edu>
To:        "Crist J. Clark" <cjc@FreeBSD.ORG>
Cc:        Gregory Neil Shapiro <gshapiro@FreeBSD.ORG>, "Rex A. Roof" <rex@gunjin.wccnet.org>, freebsd-ipfw@FreeBSD.ORG
Subject:   Re: Putting in place an incoming sendmail limit
Message-ID:  <u2s1yd2iwav.fsf@gs166.sp.cs.cmu.edu>
In-Reply-To: <20020425232444.B34367@blossom.cjclark.org>
References:  <200204252052.g3PKqrj0090391@gunjin.wccnet.org> <15560.29198.657946.738003@horsey.gshapiro.net> <20020425232444.B34367@blossom.cjclark.org>

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"Crist J. Clark" <cjc@FreeBSD.ORG> writes:

> On Thu, Apr 25, 2002 at 02:15:58PM -0700, Gregory Neil Shapiro wrote:
> > rex> In order to prevent incoming DoS attacks via multiple sendmail
> > rex> connections, I've tried adding the following ipfw rule:
> > 
> > rex> allow tcp from any to any smtp limit src-addr 1
> > 
> > rex> This works great, except that when it's triggered I get A LOT
> > rex> of messages like this:
> > 
> > rex> OUCH! cannot remove rule, count 1
> > rex> drop session, too many entries
> > 
> > Perhaps it is because that rule matches every packet into of just the TCP
> > setup packet.  You might try using the 'setup' keyword.  (Just a guess).
> 
> That's probably not the problem. Remember 'limit' rules are dynamic
> rules.
> 
> What version of FreeBSD are you running? I believe the 'OUCH!' is
> luigi's way of saying that you shouldn't be seeing that error. It
> indicates an internal error.

It is, and it's been discussed on this mailing list before. I have a patch
for this, which I've discussed with luigi in the past. For some reason, I
never heard back from him after posting it. This way or the other,
it's here if you want to apply it yourself:

http://www.freebsd.org/cgi/query-pr.cgi?pr=32600


-- 

  Dan Pelleg

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