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	Sat, 24 Apr 2004 08:43:28 PDT
Date: Sat, 24 Apr 2004 08:43:28 -0700 (PDT)
From: Alan Evans <evans.alan@sbcglobal.net>
To: Andre Oppermann <andre@freebsd.org>,
	Chuck Swiger <cswiger@mac.com>
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cc: Alan Evans <evans.alan@sbcglobal.net>
cc: net@freebsd.org
Subject: Re: TCP vulnerability
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I agree, but what's most important is to maintain
backward compatibility. If one breaks it, it's a DoS
is some sense. I also saw some postings on NetBSD
which does ratelimiting of ACKs (in response to SYNs),
and ACKs RST. IMHO, the latter is bogus - why ACK a
RST? And, the former may impose an artificial limit
of some sort.

Alan Evans

--- Andre Oppermann <andre@freebsd.org> wrote:
> Chuck Swiger wrote:
> > 
> > Alan Evans wrote:
> > > I'm sure FreeBSD is vulnerable.
> > >
> > >
> http://www.us-cert.gov/cas/techalerts/TA04-111A.html
> > >
> > > There's a draft that (sort of) addresses this.
> Should
> > > we adopt it?
> > 
> > This issue is being discussed on freebsd-security
> now, and Mike Silbersack
> > <silby@silby.com> has some patches available for
> review and testing.
> 
> There has been an additional problem in some BSD
> stacks with RST's
> which has been fixed in FreeBSD about six years ago.
>  The remaining
> things which are addressed in that paper are
> hardening measures to
> reduce the chances of a brute force blind attack. 
> There *no* vulner-
> ablility in the sense of "send packet x" and
> everything breaks.
> 
> -- 
> Andre