[Justin Walker <justin@xxxxxxx>]

On Tuesday, March 2, 2004, at 08:43 AM, Ahmed, Munaf (RDI) wrote:

> I am using Ethereal version 0.10.1(C) with WinPcap 3.0.
> When I capture network traffic Ethereal every alternate packet
> has IP and TCP checksum errors (bad checksum).
>
> I believe this is either a Pcap or Ethereal bug. I also tried
> with WinPcap 3.1 beta but still the same.
>
> Does anyone know what the fix is?

Don't know for sure about Windoze drivers, but on other systems, 
certain network interfaces with on-board IP support will handle the 
checksumming, offloading the host (at least, that's the theory).  
Therefore, when pcap/ethereal finally gets the packet, either inbound 
or outbound, the checksum is not valid.  If the transfers appear to be 
working, the packets are fine.

If you check the archives, you should see plenty of discussion on this 
subject.

Regards,

Justin

--
Justin C. Walker, Curmudgeon-At-Large  *
Institute for General Semantics        | "Weaseling out of things is 
what
                                       |  separates us from the animals.
                                       |  Well, except the weasel."
                                       |        - Homer J Simpson
*--------------------------------------*-------------------------------*