From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: TCP keepalives ignored by kernel when the contain timestamps Date: Fri, 10 Jun 2011 20:41:06 +0200 Message-ID: <1307731266.2872.4.camel@edumazet-laptop> References: <4DF0E638.2010506@uth.tmc.edu> <1307714177.4044.4.camel@edumazet-laptop> <4DF233CE.5020000@uth.tmc.edu> <4DF24154.3060505@uth.tmc.edu> <1307722621.4044.17.camel@edumazet-laptop> <4DF248C5.9050004@uth.tmc.edu> <1307724870.4044.20.camel@edumazet-laptop> <4DF25BA2.4040200@uth.tmc.edu> <1307729054.2872.0.camel@edumazet-laptop> <4DF25EE2.6020803@uth.tmc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: Charles Bearden Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:34064 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757770Ab1FJSlL (ORCPT ); Fri, 10 Jun 2011 14:41:11 -0400 Received: by wwa36 with SMTP id 36so3068517wwa.1 for ; Fri, 10 Jun 2011 11:41:10 -0700 (PDT) In-Reply-To: <4DF25EE2.6020803@uth.tmc.edu> Sender: netdev-owner@vger.kernel.org List-ID: Le vendredi 10 juin 2011 =C3=A0 13:13 -0500, Charles Bearden a =C3=A9cr= it : > On 06/10/2011 01:04 PM, Eric Dumazet wrote: > > Le vendredi 10 juin 2011 =C3=A0 13:00 -0500, Charles Bearden a =C3=A9= crit : > > > >> Each keepalive from the Win2008 machine has a 1-byte payload 0x00.= The last byte > >> of the last packet with a payload before that from the Win2008 hos= t (at > >> 14:40:18.166394 in the paste) is also 0x00. Is that what you were = asking about? > >> > > > > Yes, thats fine, thanks :) >=20 > One other thing: when tcp timestamps are disabled on the Linux (recei= ving) end,=20 > so that the Win2008 host sends keepalives without timestamps, the che= cksums in=20 > the keepalives are correct. It's only when the keepalives also contai= n=20 > timestamps that the checksums are broken. >=20 > If you think this might be a Linux kernel issue, I'll be glad to keep= working=20 > with you, but I don't want to spam this list if my problem isn't rele= vant. Thank=20 > you for your help in any case. >=20 Well, if your linux machine receives frames with a bad checksum, linux is working well : These frames must be dropped. It is a bug in the sender (Win2008 in this case).=20 I am not that surprised, given timestamps were disabled in microsoft products until very last releases (Windows Seven, and apparently winserver 2008)