I posted this question on wireshark site but the more I think about it (since 
results are the same with wireshark and windump) the more I think it is winpcap 
related.


Wireshark 1.10.2 (64 bit) on Windows 7, Wireshark 1.10 on Ubuntu 13.04 
(compiled from source), WinPcap 4.1.3

I have been troubleshooting a network that contains several Windows Embedded 
Std 7 POS systems and a back office PC that runs Win 7 Pro. When I first looked 
at the network I was amazed at the volume of errors (dup ack, retrans, tcp out 
of order). My initial look was with the back office PC on a hub with a laptop 
running Win 7 Pro and wireshark. Wondering if I had an interface issue, I put a 
netoptics tap on the back office PC connection. My windows laptop only has one 
wired ethernet interface so I put a Ubuntu Linux box with two wired interfaces 
and when I captured with it the errors magically 'disappeared'. I then bought a 
USB -> wired ethernet dongle for my laptop and ran wireshark on both interfaces 
(still on the tap) and the errors show again. I have never seen this situation 
before and don't know where to turn next - I can't trust any captures done on 
my Windows 7 laptop now and can't take my Linux desktop PC with me on the road!

Why would Wireshark on windows be showing that the network has errors 
(thousands of them per minute) but on Linux it is clean?

If I run a tcpdump (or dumpcap) capture on the Linux box then copy the file to 
the Windows machine, it does not have the errors showing.

Maybe pertinent as well.... I used an Ubuntu Live CD in the laptop that 
normally runs Windows and captured via tcpdump (using built in interface and 
USB->ethernet dongle) and came up with a clean capture that way as well. I then 
used windump and captured two separate files (one from each interface) and 
merged them. That was even worse.

This is definitely a difference between windows and linux and how they capture 
but I can't fathom how there can be such a difference.

Any insight would be muchly appreciated!
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