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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Rick Jones <rick.jones2@hp.com>
Cc: "David Miller" <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	"Perry Lorier" <perryl@google.com>,
	"Matt Mathis" <mattmathis@google.com>,
	"Yuchung Cheng" <ycheng@google.com>,
	"Neal Cardwell" <ncardwell@google.com>,
	"Tom Herbert" <therbert@google.com>,
	"Wilmer van der Gaast" <wilmer@google.com>,
	"Dave Täht" <dave.taht@bufferbloat.net>,
	"Ankur Jain" <jankur@google.com>
Subject: Re: [PATCH net-next] tcp: be more strict before accepting ECN negociation
Date: Fri, 04 May 2012 23:14:17 +0200	[thread overview]
Message-ID: <1336166057.3752.468.camel@edumazet-glaptop> (raw)
In-Reply-To: <4FA443B6.9010106@hp.com>

On Fri, 2012-05-04 at 14:01 -0700, Rick Jones wrote:
> >
> > Interesting indeed ;)
> >
> > Did you check if it was spoofed ?
> >
> > (did the 3WHS really completed)
> 
> 
> Well, the tcpdump command was still:
> 
> 
> tcpdump -i eth0 -vvv '(tcp[tcpflags]&  tcp-syn != 0)&&  (ip[1] != 0x0)'
> 
> I didn't see any SYN|ACKs go out, but netperf.org would have had to set 
> ECT for me to see a SYN|ACK going out.   FWIW, this is on a 2.6.31-15 
> (Ubuntu) kernel with net.ipv4.tcp_ecn = 2 and I don't think the SYNs 
> themselves were negotiating ECN:
> 
> 13:26:16.866007 IP (tos 0x3,CE, ttl 41, id 28850, offset 0, flags [DF], 
> proto TCP (6), length 64)
>      somesystemin.de.55363 > www.netperf.org.www: Flags [S], cksum 
> 0x4cfc (correct), seq 304457158, win 65535, options [mss 1460,nop,wscale

Probably not, or else you would see :

13:26:16.866007 IP (tos 0x3,CE, ttl 41, id 28850, offset 0, flags
[DF],proto TCP (6), length 64)
    somesystemin.de.55363 > www.netperf.org.www: Flags [SEW], cksum ...

      reply	other threads:[~2012-05-04 21:14 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-04 15:14 [PATCH net-next] tcp: be more strict before accepting ECN negociation Eric Dumazet
2012-05-04 15:54 ` Neal Cardwell
2012-05-04 16:06 ` David Miller
2012-05-04 18:09 ` Rick Jones
2012-05-04 18:23   ` Eric Dumazet
2012-05-04 18:48     ` Rick Jones
2012-05-04 19:05       ` Eric Dumazet
2012-05-04 20:20         ` Rick Jones
2012-05-04 20:36           ` Rick Jones
2012-05-04 20:49             ` Eric Dumazet
2012-05-04 21:01               ` Rick Jones
2012-05-04 21:14                 ` Eric Dumazet [this message]

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