Re: linux-kernel-digest V1 #174

Alan Cox (
Fri, 29 Sep 1995 16:17:11 +0100 (BST)

> From: (Bas V. de Bakker)
> Date: Wed, 27 Sep 1995 15:43:13 +0100
> Subject: Random TCP sequence numbers?
> Hi,
> Although I haven't seen it mentioned on this list yet, I happened to
> see patch 1.3.30 and was just browsing it. It adds a hardware random
> number generator. The comments already mention the obvious
> application of using it for TCP initial sequence numbers.
> Is this actually going to be used? Are there any disadvantages that
> I'm unaware of? I suppose one has to make sure that the numbers are
> not too close to previous ones.

The Linux tcp sequence numbers are based on a microsecond timer, not on the
BSD sequencing scheme which is vulnerable (and now fixed). You can't just
do random sequences without being in breach of the RFC which states how
the sequence numbers shoulf work.