From owner-freebsd-net Fri Jul 12 6: 6:23 2002 Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8F6F437B400 for ; Fri, 12 Jul 2002 06:06:20 -0700 (PDT) Received: from rerun.avayactc.com (rerun.avayactc.com [199.93.237.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id C916E43E58 for ; Fri, 12 Jul 2002 06:06:19 -0700 (PDT) (envelope-from mcambria@avaya.com) Received: by rerun.avayactc.com with Internet Mail Service (5.5.2653.19) id <3YWRQQQX>; Fri, 12 Jul 2002 09:06:13 -0400 Message-ID: <3A6D367EA1EFD4118C9B00A0C9DD99D7065A34@rerun.avayactc.com> From: "Cambria, Mike" To: 'Jonathan Lemon' , cambria@world.std.com, net@freebsd.org Subject: RE: xl checksum and dsniff Date: Fri, 12 Jul 2002 09:06:13 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset="iso-8859-1" Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org > -----Original Message----- > From: Jonathan Lemon [mailto:jlemon@flugsvamp.com] >> > > >My guess is that doing hw checksum by the nic could be the > issue. This is > >the only real difference I can see at present. > > > >Any ideas? > > Test your theory. Turn off hardware checksums with 'ifconfig > xl0 -txcsum' When I do 'ifconfig xl0 -txcsum', a subsequent 'ifconfig' reads as if the command had no effect. In other words, ifconfig shows options=3 still. Using tcpdump, it also still reports 'bad checksum' even though everything works fine. The man page for xl also doesn't show these commands. Perhaps they are not turned on yet? On a similar machine, running OpenBSD 3.0, dsniff works just fine. This machine doesn't have support for checksum offload (or at least, ifconfig xl0 doesn't indicate it.) MikeC To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message