Date: Wed, 17 Jul 2002 10:49:19 -0700 From: "Crist J. Clark" <crist.clark@attbi.com> To: Luigi Rizzo <rizzo@icir.org> Cc: ipfw@FreeBSD.ORG Subject: Re: Ouch! ipfw log and DoS Message-ID: <20020717174919.GB25404@blossom.cjclark.org> In-Reply-To: <20020717102119.A12639@iguana.icir.org> References: <20020716124059.A2635@iguana.icir.org> <20020717064647.GC22967@blossom.cjclark.org> <20020717022619.A8351@iguana.icir.org> <20020717165807.GA25404@blossom.cjclark.org> <20020717102119.A12639@iguana.icir.org>
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On Wed, Jul 17, 2002 at 10:21:19AM -0700, Luigi Rizzo wrote:
> On Wed, Jul 17, 2002 at 09:58:08AM -0700, Crist J. Clark wrote:
> ...
> > I just really do not think that this is the right place for such a
> > limit. I don't like the idea that the firewall code just starts
> > dropping notifications without way to know about it. Think about what
> > happens for your example, a packet comes in that gets logged which
> > triggers a syslog cascade until we hit the limit. What we end up with
> > is only logging a small windows separated by at least a second, and
> > the logs are still almost entirely filled with the syslog feedback.
>
> the alternative being having your box hung until you hard-reset it,
> i know what i would choose :)
There's still IPFIREWALL_VERBOSE_LIMIT and 'logamount' to save you
from such a fate.
If you disable log limiting AND misconfigure your rules to create
feedback loops, I would have no sympathy for you.
(Does the kernel really spend enough time generating messages that you
get a real hang (the console hangs, not just remote sessions)?)
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
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