From owner-freebsd-ipfw@FreeBSD.ORG Fri Feb 6 17:11:35 2004 Return-Path: Delivered-To: freebsd-ipfw@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4DB1C16A4CE for ; Fri, 6 Feb 2004 17:11:35 -0800 (PST) Received: from whizzo.transsys.com (whizzo.TransSys.COM [144.202.42.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0758F43D1F for ; Fri, 6 Feb 2004 17:11:34 -0800 (PST) (envelope-from louie@whizzo.transsys.com) Received: from whizzo.transsys.com (#6@localhost [127.0.0.1]) by whizzo.transsys.com (8.12.10/8.12.10) with ESMTP id i171BX0R019173; Fri, 6 Feb 2004 20:11:33 -0500 (EST) (envelope-from louie@whizzo.transsys.com) Message-Id: <200402070111.i171BX0R019173@whizzo.transsys.com> X-Mailer: exmh version 2.6.3 04/04/2003 with nmh-1.0.4 To: Thomas Vogt X-Image-URL: http://www.transsys.com/louie/images/louie-mail.jpg From: "Louis A. Mamakos" References: <40243129.7060400@gmx.net> In-reply-to: Your message of "Sat, 07 Feb 2004 01:28:25 +0100." <40243129.7060400@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 06 Feb 2004 20:11:33 -0500 Sender: louie@TransSys.COM cc: freebsd-ipfw@freebsd.org Subject: Re: ipfw2/dummynet set new mss on thy fly X-BeenThere: freebsd-ipfw@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: IPFW Technical Discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 07 Feb 2004 01:11:35 -0000 Can't you write a rule that only diverts packets with the SYN bit set? It's the only time a TCP MSS option is allowed to be set. It doesn't seem like there's any reason to send all the traffic through tcpmssd. (And the problem isn't a "wrong" windows implementation, it's broken Path MTU discovery due to overzelous filtering of ICMP.) louie > Hi > > Is it possible to modify the mss with ipfw2/dummynet? This is necessary > to fix wrong window implementations for example for adsl providers. > > Something like "modify mss=1452 tcp from any to any out recv em0 xmit > em1 tcpflags syn". (Of course this string is wrong, it's just to give > you an impression). > > I know there is tcpmssd port but it uses divert. I've to modify every > packet on gigabit lan (at least 200mb/s traffic). So tcpmssd is a bit to > slow. > > We already have a ipfw1 patch and It's not that difficult to port it to > ipfw2. But I'm not sure if ipfw2/dummynet already have something similar > implemented by default. > Any hints? > > cheers, > Thomas > _______________________________________________ > freebsd-ipfw@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw > To unsubscribe, send any mail to "freebsd-ipfw-unsubscribe@freebsd.org"