From owner-freebsd-virtualization@freebsd.org Tue Jul 7 15:04:53 2015 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A78909956BC; Tue, 7 Jul 2015 15:04:53 +0000 (UTC) (envelope-from timp87@gmail.com) Received: from mail-wi0-x229.google.com (mail-wi0-x229.google.com [IPv6:2a00:1450:400c:c05::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 433D713DD; Tue, 7 Jul 2015 15:04:53 +0000 (UTC) (envelope-from timp87@gmail.com) Received: by wifm2 with SMTP id m2so62499075wif.1; Tue, 07 Jul 2015 08:04:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=oVWz4GUQ11mx+XZIDxb74Hc25EjyzqtUWUV2oPflpng=; b=NA+dTsKVKJviyW6VuSshgXZiILa0Z1v+cgq6O5gV/xR9m6zvtKFCiYeBWrrBGZT2RN 7f326VnMww3WnqwuyZNptTw8HN5tQ/ygUzTlEPat+98ufAEPde9XskxE0NvuwEwjHZah Ni1uZrHUrvEv2/EnM5iQfMlt8uIP/yofSiY1kQ09kwqDge1f6R9tDYyYRtVjtvWnxtIf OpvXN3tkqR4itbR28j9dJzXntNUafcc9Ut2Xt+PKVQp4KzDsGgE6u1Pb6HS4hJDqXUJA B8ivIWhdrv++LGPzK2CPOafJ86e7JLZ0Ftd3SqYxR18oUVeN/CdSlfYzXVHCSjseiQ6b KyJQ== MIME-Version: 1.0 X-Received: by 10.194.7.97 with SMTP id i1mr9461703wja.107.1436281486760; Tue, 07 Jul 2015 08:04:46 -0700 (PDT) Received: by 10.28.48.207 with HTTP; Tue, 7 Jul 2015 08:04:46 -0700 (PDT) In-Reply-To: <20150707130902.GA41189@zxy.spb.ru> References: <20150707130902.GA41189@zxy.spb.ru> Date: Tue, 7 Jul 2015 18:04:46 +0300 Message-ID: Subject: Re: MS DNS doesn't answer to CURRENT under Hyper-V From: Pavel Timofeev To: Slawa Olhovchenkov Cc: freebsd-current@freebsd.org, "freebsd-virtualization@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Jul 2015 15:04:53 -0000 Well, turning off checksum offloading by `ifconfig hn0 -txcsum -rxcsum` definitely helps. As for tcpdump I'm not completely sure if I did it right, but I see "bad udp cksum" phrase: # tcpdump -i hn0 -vvv -nn udp dst port 53 tcpdump: listening on hn0, link-type EN10MB (Ethernet), capture size 262144 bytes 18:01:19.139994 IP (tos 0x0, ttl 64, id 61218, offset 0, flags [none], proto UDP (17), length 51) 192.168.25.26.45683 > 192.168.25.3.53: [bad udp cksum 0xb39e -> 0xf210!] 52886+ A? ya.ru. (23) 18:01:24.140544 IP (tos 0x0, ttl 64, id 17293, offset 0, flags [none], proto UDP (17), length 51) 192.168.25.26.12575 > 192.168.25.3.53: [bad udp cksum 0xb39e -> 0x7365!] 52886+ A? ya.ru. (23) 2015-07-07 16:09 GMT+03:00 Slawa Olhovchenkov : > On Tue, Jul 07, 2015 at 02:50:49PM +0300, Pavel Timofeev wrote: > >> Hi! >> I have a test virtual machine which runs CURRENT under Hyper-V. It's >> amd64 r285198 now. >> It can't get any response from MS DNS server. Well, it could two or >> three weeks ago, but after upgrade it's not able to do it anymore. >> Google DNS answers without problems meanwhile (sic!). >> >> What I do: >> # host google.ru 192.168.25.3 >> I see that MS DNS (192.168.25.3) server receives these packets, but >> ignores them. >> And no matter how my system asks MS DNS. Every daemon can't get response too. >> >> I know that nothing was changed in MS DNS server. No doubt. >> Then I tried different available CURRENT snapshot ISOs. >> >> FreeBSD-11.0-CURRENT-amd64-20150630-r284969-disc1.iso - MS DNS does not answer. >> >> FreeBSD-11.0-CURRENT-amd64-20150625-r284814-disc1.iso - MS DNS does not answer. >> >> FreeBSD-11.0-CURRENT-amd64-20150618-r284544-disc1.iso - MS DNS answers! >> >> So something was committed to CURRENT between 20150618 and 20150625. >> This something ruins communication with MS DNS. >> >> Then I tried latest >> FreeBSD-11.0-CURRENT-amd64-20150630-r284969-disc1.iso on bare metal - >> MS DNS answered! >> >> Looks like that something is related to Hyper-V code. >> >> Maybe it changes packets somehow? I can gather and provide more info >> (tcpdump?) if you ask, it's not a problem! > > Author: whu > Date: Wed Jun 24 06:01:29 2015 > New Revision: 284746 > URL: https://svnweb.freebsd.org/changeset/base/284746 > > Log: > TSO and checksum offloading support for Netvsc driver on Hyper-V. > > ===== > > Try tcpdump/wireshark on FreeBSD and MS DNS host. > Check validating IP/UDP checksums. > Try off checksum offloading on network interface > (ifconfig ifname -txcsum -rxcsum)