Re: TCP_MD5 and Intel e1000

On Tuesday 22 May 2007, David Miller wrote:

From: YOSHIFUJI Hideaki / 吉藤英明 <redacted>
Date: Tue, 22 May 2007 18:36:47 +0900 (JST)

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In article [ref] (at Tue, 22 May 

2007 10:57:38 +0200), Eric Dumazet [off-list ref] says:

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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