Re: incorrect tcp checksum on Linux tun interfaces?

[Rick Jones <rick.jones2 () hp com>]

On 12/04/2012 02:24 PM, Gert Doering wrote:
> Hi,
>
> On Tue, Dec 04, 2012 at 11:09:43AM -0500, Michael Richardson wrote:
> > What's curious to me is that the chsum is not zero. If it was being
> > "offloaded" into a step after the PF_PACKET interface, it would be zero,
> > right?
>
> I'm not sure.  I find this highly irritating, and I'm fairly sure that
> *here* are the folks that have seen all the funnies when tcpdumping on
> specific interfaces...

If I recall correctly, the TCP checksum is "seeded" with the 
pseudo-header checksum.  That could be passed-down separately but I 
suspect it is still functionally correct if that is simply shoved into 
the TCP checksum field.

rick jones
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