Bugtraq mailing list archives
Re: Random Sequence Numbers
From: smb () RESEARCH ATT COM (Steven M. Bellovin)
Date: Thu, 10 Feb 2000 17:35:03 -0500
In message <00Feb10.090608est.115219 () border alcanet com au>, Peter Jeremy write s:
On 2000-Feb-09 20:27:08 +1100, Omachonu Ogali <oogali () intranova net> wrote:I don't know if anyone else attempted, but I whipped up a little patch for FreeBSD that randomizes the sequence/acknowledgment numbers sent by TCP instead of incrementing it by one each time. Apply using 'patch'.Note that the patch is using libkern/random(). This function is a simple, multiplicative PNRG with 32-bits of state (all of which is `leaked' via its return value. Whilst the change might be better than a simple increment/decrement, I don't believe it provides any real security (especially in view of the %=2 operations).
I never saw the original posting to this; let me suggest that folks read RFC 1948 before doing sequence number randomization. --Steve Bellovin
Current thread:
- Re: Random Sequence Numbers Peter Jeremy (Feb 09)
- <Possible follow-ups>
- Re: Random Sequence Numbers Steven M. Bellovin (Feb 10)