From owner-freebsd-questions@FreeBSD.ORG Fri Mar 23 17:30:27 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 3075A16A40F for ; Fri, 23 Mar 2007 17:30:27 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from mail-out4.apple.com (mail-out4.apple.com [17.254.13.23]) by mx1.freebsd.org (Postfix) with ESMTP id B213813C4E1 for ; Fri, 23 Mar 2007 17:30:25 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from relay8.apple.com (relay8.apple.com [17.128.113.38]) by mail-out4.apple.com (8.13.8/8.13.8) with ESMTP id l2NHUOKX014344; Fri, 23 Mar 2007 10:30:24 -0700 (PDT) Received: from relay8.apple.com (unknown [127.0.0.1]) by relay8.apple.com (Symantec Mail Security) with ESMTP id A78C340492; Fri, 23 Mar 2007 10:30:24 -0700 (PDT) X-AuditID: 11807126-adf2dbb00000669a-a7-46040eb08821 Received: from [17.214.13.96] (cswiger1.apple.com [17.214.13.96]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by relay8.apple.com (Apple SCV relay) with ESMTP id 9655940523; Fri, 23 Mar 2007 10:30:24 -0700 (PDT) In-Reply-To: <861wjfev78.fsf@king.swox.se> References: <868xdqnnzd.fsf@king.swox.se> <86odmlhzn8.fsf@king.swox.se> <4A2495E9-3060-4D05-A7B4-7CCC019AFEB8@mac.com> <861wjfev78.fsf@king.swox.se> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Chuck Swiger Date: Fri, 23 Mar 2007 10:30:23 -0700 To: Torbjorn Granlund X-Mailer: Apple Mail (2.752.2) X-Brightmail-Tracker: AAAAAA== 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 17:30:27 -0000 On Mar 23, 2007, at 10:16 AM, Torbjorn Granlund wrote: >>> 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. It's not intentional. I might be confusing us both. :-) > (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. Uh, yes. I meant this packet: bang.swox.se.smtp > vm.se.lsoft.com.58679: S 3183232720:3183232720 (0) ack 678305701 > (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. You're right-- the SYN+ACK reply to a connection open (bare SYN) should reply with SEQ = ISS + 1 to acknowledge the SYN (which counts as a byte). -- -Chuck