From owner-freebsd-hackers@FreeBSD.ORG Tue May 27 14:00:19 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 62C9237B401 for ; Tue, 27 May 2003 14:00:19 -0700 (PDT) Received: from symonds.net (ca1.symonds.net [66.92.42.136]) by mx1.FreeBSD.org (Postfix) with ESMTP id A495743F75 for ; Tue, 27 May 2003 14:00:18 -0700 (PDT) (envelope-from ashish@symonds.net) Received: from localhost (symonds.net) [127.0.0.1] by symonds.net with smtp (Exim 3.35 #1 (Debian)) id 19KlYO-000209-00; Tue, 27 May 2003 14:00:16 -0700 Received: from 203.192.199.30 (SquirrelMail authenticated user ashish) by secure.symonds.net with HTTP; Wed, 28 May 2003 02:30:16 +0530 (IST) Message-ID: <1392.203.192.199.30.1054069216.squirrel@secure.symonds.net> Date: Wed, 28 May 2003 02:30:16 +0530 (IST) From: "Ashish Kulkarni" To: Importance: Normal MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit cc: ashish@symonds.net Subject: Re: changing the ToS in IP Header X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ashish@symonds.net List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 May 2003 21:00:19 -0000 Kenjiro Cho wrote: > Tell your ISP not to use 0x02; it violates the standard. > You may modify the upper 6 bits for an arbitrary value, though. Well, my cable ISP provides a 3rd party Windows-only client that enables forwarding of packets only when logged in. I've reverse engineering that protocol sucessfully, and it requires the TOS to be 0x02 ... I imagine this TOS is only valid uptil the gateway, after which a different TOS is used. Anyway, all this is unofficial so I can't really go to my ISP and mention it ;-) > The lower 2 bits of the (now deprecated) TOS field are officially > assigned to ECN (RFC3168). 0x02, ECT(0), is used to indicate that the > sender is ECN-capable. > > ALTQ supports diffserv and is capable of rewriting the upper 6 bits of > the TOS field. > http://www.csl.sony.co.jp/~kjc/software.html I have one question: as you said, I can use ALTQ to reset all the upper 6 bits to zero, so as to get the pattern 0x02 (using the kernel patch by Terry Lambert). Will this have any implications for its working and for ECN? I need this because several protocols (ssh, etc) use a modified TOS, which I want to be reset to default value. Thanks, Ashish