Ethereal-dev: Re: [Ethereal-dev] reassembling TCP even if checksums are incorrect

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Thu, 21 Jul 2005 08:29:10 -0700
LEGO wrote:

I have some captures made on a sun in which TCP checksums are
incorrect for every packet (They are probably calculated after they
are passed to snoop, the service works OK so on the wire I assume
those are correct).


Yes, this is

	http://www.ethereal.com/faq#q5.14

Ultimately, what would be nice would be to
1) get, from the capture mechanism, an indication of what packets are being sent by the machine 

and
2) get, from the interface enumeration mechanism, an indication of whether the interface does checksum offloading 

and turn off the checksum check on outgoing packets on those interfaces.


The TCP dissector does not reassemble
[Unreassembled Packet [incorrect TCP checksum]: GIOP]

Is it OK if we add a prefererence to TCP so it can ignore checksums
when reassembling in that condition?
There's already a preference to turn off checksum checking, which is useful if you're capturing traffic to and from a machine with checksum offloading.