tcpdump mailing list archives
Re: incorrect tcp checksum on Linux tun interfaces?
From: Rick Jones <rick.jones2 () hp com>
Date: Tue, 04 Dec 2012 14:34:24 -0800
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.
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Current thread:
- incorrect tcp checksum on Linux tun interfaces? Gert Doering (Dec 04)
- Re: incorrect tcp checksum on Linux tun interfaces? Michael Richardson (Dec 04)
- Re: incorrect tcp checksum on Linux tun interfaces? Gert Doering (Dec 04)
- Re: incorrect tcp checksum on Linux tun interfaces? Rick Jones (Dec 10)
- Re: incorrect tcp checksum on Linux tun interfaces? Gert Doering (Dec 04)
- Re: incorrect tcp checksum on Linux tun interfaces? Michael Richardson (Dec 04)