netdev - Re: UDP checksum broken since 2.6.18?

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Message-ID: <4654186C.8050505@openpma.org>
Date:	Wed, 23 May 2007 10:33:16 +0000
From:	"Thomas B. Rücker" <dm8tbr@...npma.org>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	shemminger@...ux-foundation.org, pg@...ureware.at,
	netdev@...r.kernel.org
Subject: Re: UDP checksum broken since 2.6.18?

Herbert Xu wrote:
> "Thomas B. R??cker" <dm8tbr@...npma.org> wrote:
>   
>> Stephen Hemminger wrote:
>>     
>>> The packet passed to packet capture programs may not have a valid checksum
>>> if you have checksum offload configured on the device.  What kind of hardware
>>> do you have on sender and receiver? 
>>>       
>> The c-snippet uses 127.x.x.x --> loopback
>>     
>
> We never compute the complete checksum for loopback so that explains
> the bogus checksum.
>   
Does this also explain why wireshark thinks the checksum is right when
tested on <=2.6.17?

Cheers

Thomas
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