Date: Wed, 8 Jul 2015 11:22:24 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Pavel Timofeev <timp87@gmail.com> Cc: freebsd-current@freebsd.org, "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: MS DNS doesn't answer to CURRENT under Hyper-V Message-ID: <20150708082224.GB44094@zxy.spb.ru> In-Reply-To: <CAAoTqft_u1YEOGf6pThhHd-JuYoGnxzQxFpo-57SCUJ0OksWGw@mail.gmail.com> References: <CAAoTqftvtQunx%2BWCL4%2BBz-mYSgqCTcGx1aAyemfaz%2B=0ogZuWw@mail.gmail.com> <20150707130902.GA41189@zxy.spb.ru> <CAAoTqfsUfdAP1G=U4eDg3hfmuHtoosgGjOd9gMrehX%2BrcxaiJw@mail.gmail.com> <20150707154906.GA44094@zxy.spb.ru> <CAAoTqft_u1YEOGf6pThhHd-JuYoGnxzQxFpo-57SCUJ0OksWGw@mail.gmail.com>
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On Wed, Jul 08, 2015 at 11:05:39AM +0300, Pavel Timofeev wrote: > Ok, r284746 is the root of the problem. MS DNS works under r284745 and > doesn't work under r284746. > Slawa, what should I look at in wireshark output? I think developers can want look at same packet before entering in NIC and after receiving MS DNS server. I.e. hexdump of all packet. FreeBSD's tcpdump do this by `tcpdump -X` for IPv4 payload and `tcpdump -XX` for IPv4 and Ethernet payload (wireshark by default include ethernet, for easy comparasion do same). wireshar do same by 'Export Packet Dissections' 'as plain text' with checked 'Packet Deatils - All expanded' and 'Packet Bytes'. This is will be very verbose output. > 2015-07-07 18:49 GMT+03:00 Slawa Olhovchenkov <slw@zxy.spb.ru>: > > On Tue, Jul 07, 2015 at 06:04:46PM +0300, Pavel Timofeev wrote: > > > >> 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) > > > > tcpdump "bad udp cksum" is normal on FreeBSD host in case checksum > > offload (and may be need only for help finding issuse in code). Need > > wireshark capturing from MS DNS host (or from mirroring port).
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