From owner-freebsd-questions@FreeBSD.ORG Fri Mar 23 17:17:00 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5DCE916A404 for ; Fri, 23 Mar 2007 17:17:00 +0000 (UTC) (envelope-from tg@swox.com) Received: from king.swox.se (king.swox.se [195.198.203.150]) by mx1.freebsd.org (Postfix) with ESMTP id C097313C4CE for ; Fri, 23 Mar 2007 17:16:59 +0000 (UTC) (envelope-from tg@swox.com) Received: by king.swox.se (Postfix, from userid 1001) id 0F9277DB8; Fri, 23 Mar 2007 18:16:59 +0100 (CET) To: Chuck Swiger References: <868xdqnnzd.fsf@king.swox.se> <86odmlhzn8.fsf@king.swox.se> <4A2495E9-3060-4D05-A7B4-7CCC019AFEB8@mac.com> From: Torbjorn Granlund Sender: tege@king.swox.se Original-Sender: tg@swox.com Date: 23 Mar 2007 18:16:59 +0100 In-Reply-To: <4A2495E9-3060-4D05-A7B4-7CCC019AFEB8@mac.com> Message-ID: <861wjfev78.fsf@king.swox.se> Lines: 34 User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: freebsd-questions@freebsd.org Subject: Re: TCP conection problems IBM VM -> FreeBSD X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Mar 2007 17:17:00 -0000 Chuck Swiger writes: On Mar 22, 2007, at 12:00 PM, Torbjorn Granlund wrote: >> The second line should have been smtp.swox.se.smtp SYN+ACK'ing the >> ISN of 27523124. vm is sending a RST to that because the sequence >> #'s don't match. It's also odd that the set of options being >> listed >> don't correspond at all...if you run the tcpdump for several >> minutes, >> can you track down other SYN requests which do correspond? > > These are the ones the correspond. They come in bursts like that. If > I let it run a little longer, I get output like this: > > 19:45:56.939958 IP vm.se.lsoft.com.58679 > bang.swox.se.smtp: S > 678305700:678305700(0) win 8192 0,nop,nop,nop,timestamp 2317060084 0> > 19:45:56.940154 IP bang.swox.se.smtp > vm.se.lsoft.com.58679: S > 3183232720:3183232720(0) ack 678305701 win 57344 1460,nop,wscale 0,nop,nop,timestamp 24588210 2317060084> Notice the ACK from vm.se.lsoft.com is off by one, but the timestamp option corresponds. Looks to be a bug with the vm machine, the bang machine is behaving properly per the TCP requirements. Now you're confusing me. (1) There is no ACK sent from vm.se.lsoft.com. The only ACKs sent are i the other directions, as per the tcpdumps above. (2) The ACKs are not off by one, or if you prefer, ACKs on TCP are always off by one. They are one higher than one would expect. -- Torbjörn