Feeny, Michael (TD&DS, Applications Infrastructure Svcs.) wrote:
> Hi all…
>
>
>
> I posted this to the Winpcap-users forum, but I have not gotten a
> response yet. Perhaps someone here has some experience or insight…
>
>
>
> I used Ethereal (0.10.14) to capture packets yesterday (Winpcap version
> 3.1). When I open the resultant Ethereal file, I notice that about
> every 5 or 10 packets, the timestamp is roughly 13 seconds earlier than
> that of the previous packet.
The questions I would be asking are:
What could be fiddling with the system clock?
Are these happening at consistent intervals throughout the trace? (e.g
every 0.05 secs)
What else is running on the box?
> Looking more closely, I see a clump of packets with timestamps that
> increase normally, then a clump that are 13 seconds earlier (but whose
> timestamps also increase normally), then a clump that are 13 seconds
> later (lining up with the 1^st clump), then a 13-seconds-earlier clump,
> etc., etc., etc.
>
>
>
> I’m probably not explaining this well L. Here is a sample of the
> timestamps – this should make it clearer…
>
>
>
> 14:26:35.475498
>
> 14:26:35.475604
>
> 14:26:35.475632
>
> 14:26:49.087976 (Jumps ahead ~13.5 seconds)
>
> 14:26:49.132457
>
> 14:26:49.132573
>
> 14:26:49.132604
>
> 14:26:49.134084
>
> 14:26:35.525248 (Jumps back ~13.5 seconds)
>
> 14:26:35.525376
>
> 14:26:35.525567
>
> 14:26:49.283965 (Jumps ahead ~13.5 seconds)
>
> 14:26:49.882512
>
> 14:26:49.882613
>
> 14:26:49.882645
>
> … this pattern continues forever and ever (or, at least for the 35
> minutes of the capture)
>
>
>
> Has anyone seen this? Any ideas?
>
>
>
> If I understand how Winpcap works (that’s a big “IF”), Winpcap grabs the
> packet, applies a timestamp using the system clock, passes it to
> Ethereal, who gives it the next frame number and adds it to the packet
> set, and waits for the next packet. So, how these timestamps are
> showing this behavior has got me good and puzzled J.
>
>
>
> ADDITIONAL INFO
>
> OS: MS Windows 2000 SP2
>
> Proc: x86 Family 6 Model 8 Stepping 3
>
> NIC: Compaq NC3163 Fast Ethernet NIC
>
> Thx much,
>
--
There's no point in being grown up if you can't be childish sometimes.
-- Dr. Who
