linux-kernel - Re: TCP_MD5 and Intel e1000

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Message-Id: <20070522.031432.08079709.davem@davemloft.net>
Date:	Tue, 22 May 2007 03:14:32 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	yoshfuji@...ux-ipv6.org
Cc:	dada1@...mosbay.com, webmaster@...eraudio.de,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: TCP_MD5 and Intel e1000

From: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@...ux-ipv6.org>
Date: Tue, 22 May 2007 18:36:47 +0900 (JST)

> In article <20070522105738.f03cb83b.dada1@...mosbay.com> (at Tue, 22 May 2007 10:57:38 +0200), Eric Dumazet <dada1@...mosbay.com> says:
> 
> > > I have tried to set up quagga with tcp-md5 support from kernel. All seems ok
> > > with a intel e100 NIC, but as i testetd with a intel e1000 NIC the tcp
> > > packets have an invalid md5 digest.
> > > If i run tcpdump on the mashine the packets are generated, it shows on the
> > > outgoing interface invalid md5 digests.
> > > Are there known issues about tcp-md5 and e1000 NICs?
> :
> > You could try "ethtool -K tx off", and/or other ethtool -K settings
> 
> Disabling offloading should help; currently tcp-md5 stack
> blindly copy md5-signature from the first segment
> which is not appropriate for rest of segments.

It is clear we should disable TSO for sockets making use of TCP-MD5.
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