From owner-freebsd-net@FreeBSD.ORG Sat May 14 14:52:32 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2A1EC1065673; Sat, 14 May 2011 14:52:32 +0000 (UTC) (envelope-from to.my.trociny@gmail.com) Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com [209.85.214.54]) by mx1.freebsd.org (Postfix) with ESMTP id 781188FC19; Sat, 14 May 2011 14:52:30 +0000 (UTC) Received: by bwz12 with SMTP id 12so4057236bwz.13 for ; Sat, 14 May 2011 07:52:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:from:to:cc:subject:references:x-comment-to :sender:date:in-reply-to:message-id:user-agent:mime-version :content-type; bh=6xrLNn5Bh+NIZZVtpY3+ByFrwxFdw9qWWOWnjeSmqrA=; b=V7+dUom4DebxlJr97i1LcHVN8OUlGOeEvmUqd/5x6oop//cfjccA12RekGuekQx0a7 mZAQ7pZ7d8LdMQ/N64/1iHff7MEFChsKjhNpfCpr79yzBlubLuc2SVWIY2ekHchh9Ey+ bm/DHgIVXxIJf2SBfejmYbLim8i7A6lv0WI3w= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:references:x-comment-to:sender:date:in-reply-to :message-id:user-agent:mime-version:content-type; b=Ci+SDcZECA+aM4lefOY3n7d9u1B9UeTFw7T/DrxD8mIP+y1TgUGh0zaGCqUem9+Eig xSe3eIvJXAU/hVRhKIQf+muAKYkGGLpGCJ2aOF2vWeWoNamKsYJshPak4e6DpGABTP3m OcxQZ7X9gCU/AhMUdCJAxFEd4TfrboCQnwuSQ= Received: by 10.204.151.204 with SMTP id d12mr1868841bkw.127.1305384749258; Sat, 14 May 2011 07:52:29 -0700 (PDT) Received: from localhost ([95.69.172.154]) by mx.google.com with ESMTPS id d10sm1590806bkw.23.2011.05.14.07.52.27 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 14 May 2011 07:52:28 -0700 (PDT) From: Mikolaj Golub To: Chuck Swiger References: <5BD73B66-9A84-4640-A43F-4970BDC584BA@mac.com> X-Comment-To: Chuck Swiger Sender: Mikolaj Golub Date: Sat, 14 May 2011 17:52:25 +0300 In-Reply-To: <5BD73B66-9A84-4640-A43F-4970BDC584BA@mac.com> (Chuck Swiger's message of "Fri, 13 May 2011 14:38:34 -0700") Message-ID: <86zkmpl4gm.fsf@kopusha.home.net> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: freebsd-net@freebsd.org, Ivan Voras , John Baldwin Subject: Re: Spurious ACKs, ICMP unreachable? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 14 May 2011 14:52:32 -0000 On Fri, 13 May 2011 14:38:34 -0700 Chuck Swiger wrote: CS> On May 13, 2011, at 1:07 PM, Ivan Voras wrote: >> I'm seeing an an unusual problem at a remote machine; this machine is >> the FreeBSD server, and the client is a probably Windows machine (but I >> don't know the details yet). Something happens which causes FreeBSD to >> send ACKs to the client, and the client to send ICMP unreachable >> messages to the server. It is most likely a configuration error at the >> remote site but I have no idea how to verify this. CS> Let's look at just one connection: CS> 18:56:02.711942 IP server.http > client.4732: Flags [.], ack 2110905191, win 0, length 0 CS> 18:56:02.713155 IP server.http > client.4732: Flags [.], ack 1, win 65535, length 0 CS> The packet is FreeBSD webserver sending ACKs with zero window size; CS> that's a sign of congestion that the client should not be sending more CS> data and instead doing periodic window probes until the local box opens CS> the window again. The next packet on the same connection then ACK's CS> something outside of the window with a 64K window size. That's wrong; CS> the other side probably sends an RST and the ICMP error. If you have TSO CS> enabled, try turning it off. Might be this the thing that jhb@ was fixing in r221346? -- Mikolaj Golub