From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick McHardy <kaber@trash.net>
Subject: Re: sky2 hw csum failure [was Re: sky2 large MTU problems]
Date: Thu, 25 May 2006 13:15:39 +0200
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Cc: Stephen Hemminger <shemminger@osdl.org>, netdev@vger.kernel.org,
	Netfilter Developer <netfilter-devel@lists.netfilter.org>
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To: Daniel J Blueman <daniel.blueman@gmail.com>
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Daniel J Blueman wrote:
> On 25/05/06, Patrick McHardy <kaber@trash.net> wrote:
> 
>> Daniel, is there an easy way to reproduce the checksum failure?
> 
> 
> In short, no. This was seen when packets may have been truncated by
> large MTU (eg 9000) problems in the sky2 driver transmit path.
> 
> There is a small chance that this could relate to transmitting with an
> MTU of 9000 (possibly with receiving with an MTU of 1500 too)

Unfortunately I can't test this myself because my other NICs don't
support MTUs > 1500.

> On that interface, the only rules that were being exercised were:
> 
> iptables -t filter -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
> iptables -t filter -A INPUT -p tcp -m tcp --dport 445 --syn -j ACCEPT # SMB
> iptables -t filter -A INPUT -j DROP

That shouldn't cause any packet modifications. Can you trigger the
checksum failures without netfilter?