From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757537Ab2EVQ6y (ORCPT ); Tue, 22 May 2012 12:58:54 -0400 Received: from g5t0006.atlanta.hp.com ([15.192.0.43]:17061 "EHLO g5t0006.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751892Ab2EVQ6x (ORCPT ); Tue, 22 May 2012 12:58:53 -0400 Message-ID: <4FBBC5CB.20201@hp.com> Date: Tue, 22 May 2012 09:58:51 -0700 From: Rick Jones User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Miklos Szeredi CC: Eric Dumazet , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: tcp timestamp issues with google servers References: <87r4ujno34.fsf@tucsk.pomaz.szeredi.hu> <1337278363.3403.39.camel@edumazet-glaptop> <87zk90s0em.fsf@tucsk.pomaz.szeredi.hu> <1337701259.3361.208.camel@edumazet-glaptop> <87mx50rz34.fsf@tucsk.pomaz.szeredi.hu> In-Reply-To: <87mx50rz34.fsf@tucsk.pomaz.szeredi.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/22/2012 08:54 AM, Miklos Szeredi wrote: > Eric Dumazet writes: > >> On Tue, 2012-05-22 at 17:25 +0200, Miklos Szeredi wrote: >> >>> So it appears. The IP address is certainly registered to Google. >> >> Good, but you could have a middlebox doing transparent proxying. >> >> The SYNACK could be send by this box. > > Okay. Is there a way to find out whether there is a middlebox or not? The source IP in the trace was a 192.168 IP - is it possible/desirable to reproduce the problem without the device doing NAT in the path? What is your "public" IP address? Given that, and the IP address to which you are connecting, it should be possible to validate the RTT you are seeing. If the geographic/topological location of the destination Google IP address is far enough from your public source IP that would show whether the RTT you are seeing is even physically possible and so could suggest there is a middlebox (other than your NAT), though it couldn't show there was not a middlebox. rick jones