From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/3] Support arbitrary initial TCP timestamps Date: Sun, 17 Feb 2008 23:33:30 -0800 (PST) Message-ID: <20080217.233330.157255657.davem@davemloft.net> References: <1203097630-13237-1-git-send-email-ggriffin.kernel@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: ggriffin.kernel@gmail.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:33518 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753795AbYBRHcx (ORCPT ); Mon, 18 Feb 2008 02:32:53 -0500 In-Reply-To: <1203097630-13237-1-git-send-email-ggriffin.kernel@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Glenn Griffin Date: Fri, 15 Feb 2008 09:47:08 -0800 > Introduce the ability to send arbitrary initial tcp timestamps that are not > tied directly to jiffies. The basic conecpt is every tcp_request_sock and > tcp_sock now has a ts_off offset that represents the difference between > tcp_time_stamp and the timestamp we send and expect to > receive. > > This has the advantage of not divulging system information (uptime) > depending on the policy chosen for the initial timestamps. > > A policy where ts_off is always set to zero should produce no change in > behavior. The policy implemented is not intended for real use, but just as > a simple example. A realistic example would probably be similar to the tcp > init sequence generator. > > Signed-off-by: Glenn Griffin Adding yet another member to the already bloated tcp_sock structure to implement this is too high a cost. I would instead prefer that there be some global random number calculated when the first TCP socket is created, and use that as a global offset. You can even recompute it every few hours if you like. We do similar things already elsewhere.