From owner-freebsd-net Thu Jul 26 10:24:25 2001 Delivered-To: freebsd-net@freebsd.org Received: from falcon.mail.pas.earthlink.net (falcon.mail.pas.earthlink.net [207.217.120.74]) by hub.freebsd.org (Postfix) with ESMTP id BD91737B408; Thu, 26 Jul 2001 10:24:17 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from mindspring.com (dialup-209.245.129.59.Dial1.SanJose1.Level3.net [209.245.129.59]) by falcon.mail.pas.earthlink.net (EL-8_9_3_3/8.9.3) with ESMTP id KAA16960; Thu, 26 Jul 2001 10:24:02 -0700 (PDT) Message-ID: <3B605255.EDBA1D3C@mindspring.com> Date: Thu, 26 Jul 2001 10:24:37 -0700 From: Terry Lambert Reply-To: tlambert2@mindspring.com X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Barney Wolff Cc: Sean Chittenden , Mike Silbersack , arch@FreeBSD.ORG, net@FreeBSD.ORG Subject: Re: TCP sequence numbers: RFC1948 patch ready for testing References: <20010725032805.A21133@tp.databus.com> <20010725185434.V35719-100000@achilles.silby.com> <20010725173859.C65546@rand.tgd.net> <20010725213812.A28964@tp.databus.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Barney Wolff wrote: > Existing sessions would not be broken by rekeying. The risk is that > some new session might fail - and this can happen any time a new > session with the same tuple starts shortly after an old session which > spans the rekeying event ends. > > If it becomes possible to brute-force (or smart-sneak) reverse MD5 > in less time than the life of the Universe, the right answer is to > change the hash, not to rekey. > > You guys don't seem to want to believe RFC1948: > > Note that the secret cannot easily be changed on a live machine. > Doing so would change the initial sequence numbers used for > reincarnated connections; to maintain safety, either dead connection > state must be kept or a quiet time observed for two maximum segment > lifetimes after such a change. > > Have you asked Steve Bellovin whether he still > stands by those words? He's not that unapproachable, despite being > one of the most prominent folks in computer networking and security > around. But he earned that reputation by being right, pretty close > to 100% of the time. Consider that sequence number rollover is faster than you think on a Gigabit system. 200,000 packets a second on unoptimized firmware is not impossible, and the theoretical maximum is closer to 1/2 million a second... -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message