Messages in this thread | | | Date | Wed, 21 Apr 2004 20:45:42 -0400 (EDT) | From | James Morris <> | Subject | Re: tcp vulnerability? haven't seen anything on it here... |
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On Wed, 21 Apr 2004, David S. Miller wrote:
> On Wed, 21 Apr 2004 19:03:40 +0200 > Jörn Engel <joern@wohnheim.fh-wedel.de> wrote: > > > Heise.de made it appear, as if the only news was that with tcp > > windows, the propability of guessing the right sequence number is not > > 1:2^32 but something smaller. They said that 64k packets would be > > enough, so guess what the window will be. > > Yes, that is their major discovery. You need to guess the ports > and source/destination addresses as well, which is why I don't > consider this such a serious issue personally. > > It is mitigated if timestamps are enabled, because that becomes > another number you have to guess. > > It is mitigated also by randomized ephemeral port selection, which > OpenBSD implements and we could easily implement as well.
What about the techniques mentioned in http://www.ietf.org/internet-drafts/draft-ietf-tcpm-tcpsecure-00.txt ?
Curiously there is no mention of port guessing or timestamps there.
- James -- James Morris <jmorris@redhat.com>
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