From owner-freebsd-hackers Tue May 28 18:15:29 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from InterJet.dellroad.org (adsl-63-194-81-26.dsl.snfc21.pacbell.net [63.194.81.26]) by hub.freebsd.org (Postfix) with ESMTP id EE00837B40F; Tue, 28 May 2002 18:15:15 -0700 (PDT) Received: from arch20m.dellroad.org (arch20m.dellroad.org [10.1.1.20]) by InterJet.dellroad.org (8.9.1a/8.9.1) with ESMTP id SAA35559; Tue, 28 May 2002 18:01:14 -0700 (PDT) Received: (from archie@localhost) by arch20m.dellroad.org (8.11.6/8.11.6) id g4T10MX89078; Tue, 28 May 2002 18:00:22 -0700 (PDT) (envelope-from archie) From: Archie Cobbs Message-Id: <200205290100.g4T10MX89078@arch20m.dellroad.org> Subject: Re: Bad TCP checksum In-Reply-To: <20020523081803.GA1730@torment.storming.org> "from Fred Souza at May 23, 2002 11:18:03 am" To: cseg@storming.org Date: Tue, 28 May 2002 18:00:22 -0700 (PDT) Cc: stable@FreeBSD.ORG, hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL88 (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Fred Souza writes: > I'm experiencing something weird with my 4.6-RC box (compile of May 18). > What happens is that for some hosts it just won't calculate the > checksum properly, and thus my box is unable to start TCP connections > to those hosts. Here's a piece of the output of tcpdump: > > 19:16:55.759657 me.50441 > somehost.http: S [bad tcp cksum fffe!] > 2079216431:2079216431(0) win 65535 timestamp 797082 0> (DF) [tos 0x10] (ttl 96, id 41580, len 60) > > Additional info that might help: The default route goes through the > tun0 interface, my ADSL service uses PPPoE and therefore I cannot > think of any other way to work it out on FreeBSD. ppp(8) was compiled > in the same day as the kernel, and I tried unloading firewalling and > nothing different occured (at least apparently). NAT is disabled here. Sounds like it might be the delayed checksum code. What Ethernet device driver are you using? -Archie __________________________________________________________________________ Archie Cobbs * Packet Design * http://www.packetdesign.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message