Ethereal-dev: Re: [Ethereal-dev] NetXray / Sniffer Time Codes [Fwd: NetXRay timing base]

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From: Chris Jepeway <thai-dragon@xxxxxxxxxxxx>
Date: Thu, 15 Feb 2001 17:51:46 -0500
> Shortly after discovering some timing problems with Ethereal and
> NetXray, I tried to verify the timing factors listed.  Unfortunately,
> the supplied correction factors were still off by about 10 seconds per
> day.  Calculations yielded a value of 0.8382229.
Odd.  I did something similar and got a value of 0.8380951
from (what I believe to be) Sniffer Pro 4.0 software running
on NT.

Your .cap file has a version of 2.002, while the ones I based
my calcs on is version 2.001.  It doesn't seem likely that the
two would differ in the way that they do, but, well, they do.

Could you send any more short .cap files?  Perhaps with
corresponding .enc files built from the same capture?

> Jason House
Chris.

> > There are two candidate bases in the mailings sent out.
> > A numerical based estimate is 88/105 (=.8380952...) correction factor.
> > Another guess is .838096.  That number is based on similarity to
> > something else...
> >
> > J. House
Actually, I banged out a (stupid) Perl script to go search for
proper fractions that were near the .8380951 value calculated
using the .cap files I had.  Clearly, the excerpt Guy provided
of the ISA System Architecture doc is the real deal, and 88/105
should be dropped from consideration.