Re: TCP_MD5 and Intel e1000

From: Marc Donner
Date: Tue May 22 2007 - 06:56:43 EST


On Tuesday 22 May 2007, David Miller wrote:
> From: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@xxxxxxxxxxxxxx>
> Date: Tue, 22 May 2007 18:36:47 +0900 (JST)
>
> > In article <20070522105738.f03cb83b.dada1@xxxxxxxxxxxxx> (at Tue, 22 May
2007 10:57:38 +0200), Eric Dumazet <dada1@xxxxxxxxxxxxx> 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.

disabling tso works. thanks
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