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Date:      Tue, 17 Jul 2001 20:29:02 -0700
From:      Kris Kennaway <kris@obsecurity.org>
To:        Mike Silbersack <silby@silby.com>
Cc:        freebsd-arch@FreeBSD.ORG
Subject:   Re: TCP Initial Sequence Numbers: We need to talk
Message-ID:  <20010717202901.A89611@xor.obsecurity.org>
In-Reply-To: <20010717212424.X3382-100000@achilles.silby.com>; from silby@silby.com on Tue, Jul 17, 2001 at 09:49:03PM -0500
References:  <20010717212424.X3382-100000@achilles.silby.com>

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On Tue, Jul 17, 2001 at 09:49:03PM -0500, Mike Silbersack wrote:

> In order to meet these requirements, I propose that we use the following
> system:
>=20
> For SYN-ACKs:  Use the value of arc4random() as our ISN.
>=20
> For SYNs:  Use the value generated by the rfc1948 scheme, with the
> modification that the secret used in the hash be changed on a weekly
> basis.  (This will break recycling for perhaps a minute a week, but it
> will ensure that the hash can not be bruteforced and also make sure that
> the system's uptime cannot be easily tracked.)
>=20
> Comments are appreciated.

If you're going to implement RFC 1948, why not just implement RFC
1948? :-)

Kris

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