Thanx All,
> Are they all packets being sent by the machine running Ethereal?
Yes and...
>
> Does your network interface support TCP checksum offloading? (Windows
> 2000 can support checksum offloading on network interfaces.)
Yes!
I think I'll just ignore checksums from my PC.
Brett Wheeler
Network Administrator
Daramalan College
Dickson ACT 2602
Australia
Mob (+61) 0417 228 714
email brett.wheelerATdaramalanc.act.edu.au
****************************
* Only the good die young, *
* I love my immortality. *
****************************
> -----Original Message-----
> From: ethereal-users-admin@xxxxxxxxxxxx
> [mailto:ethereal-users-admin@xxxxxxxxxxxx]On Behalf Of Guy Harris
> Sent: Wednesday, 26 February 2003 9:33 AM
> To: Brett Wheeler
> Cc: ethereal-users@xxxxxxxxxxxx
> Subject: Re: [Ethereal-users] TCP Checksum Incorrect
>
>
> On Wed, Feb 26, 2003 at 09:19:30AM +1100, Brett Wheeler wrote:
> > Running Ethereal 0.9.3 on Win 2k with WinPcap 2.3 over a Netware 6.0
> > Network.
> >
> > I have been noticing lately there have been quite a few (appx 30%) TCP
> > packets showing an incorrect checksum.
>
> Are they all packets being sent by the machine running Ethereal?
>
> Does your network interface support TCP checksum offloading? (Windows
> 2000 can support checksum offloading on network interfaces.)
>
> If both are the case, this is probably normal - for outgoing packets
> sent on an interface that does checksum offloading, the TCP code in the
> OS will *not* compute a checksum for the packet, and will *not* set the
> checksum in the packet, before it's sent to the network interface, which
> means it will also not set it before it's handed to the WinPcap driver.
>
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>