Date: Thu, 26 Jul 2001 10:24:37 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Barney Wolff <barney@databus.com> Cc: Sean Chittenden <sean-freebsd-arch@chittenden.org>, Mike Silbersack <silby@silby.com>, arch@FreeBSD.ORG, net@FreeBSD.ORG Subject: Re: TCP sequence numbers: RFC1948 patch ready for testing Message-ID: <3B605255.EDBA1D3C@mindspring.com> References: <20010725032805.A21133@tp.databus.com> <20010725185434.V35719-100000@achilles.silby.com> <20010725173859.C65546@rand.tgd.net> <20010725213812.A28964@tp.databus.com>
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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 <smb@research.att.com> 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
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