Re: Question about tcp hash function tcp_hashfn()

Brian F. G. Bidulock
2006-06-01T07:11:28Z

Evgeniy,

On Thu, 01 Jun 2006, Evgeniy Polyakov wrote:

> On Thu, Jun 01, 2006 at 12:46:08AM -0600, Brian F. G. Bidulock (bidulock@openss7.org) wrote:
> > > Since pseudo-randomness affects both folded and not folded hash
> > > distribution, it can not end up in different results.
> >
> > Yes it would, so to rule out pseudo-random effects the pseudo-
> > random number generator must be removed.
> >
> > >
> > > You are right that having test with 2^48 values is really interesting,
> > > but it will take ages on my test machine :)
> >
> > Try a usable subset; no pseudo-random number generator.
>
> I've run it for 2^30 - the same result: folded and not folded Jenkins
> hash behave the same and still both results produce exactly the same
> artifacts compared to XOR hash.

But not without the pseudo-random number generation... ?

>
> Btw, XOR hash, as completely stateless, can be used to show how
> Linux pseudo-random generator works for given subset - it's average of
> distribution is very good.

But its distribution might auto-correlate with the Jenkins function.
The only way to be sure is to remove the pseudo-random number generator.

Just try incrementing from, say, 10.0.0.0:10000 up, resetting port number
to 10000 at 16000, and just incrementing the IP address when the port
number wraps, instead of pseudo-random, through 2^30 loops for both.
If the same artifacts emerge, I give in.

Can you show the same artifacts for jenkins_3word?