Re: [9fans] DNS problem

[Sergey Zhilkin <szhilkin@gmail.com>]

Hi ! Seems like that is an old google dns issue, look at
http://9fans.net/archive/2008/10/37

On Tue, Nov 23, 2010 at 12:48 PM, Pavel Klinkovsky
<pavel.klinkovsky@gmail.com> wrote:
>
> Hi all,
>
> I am using Plan9 server as my home server (ip=192.168.15.20)
> controlling DNS names in my LAN and relaying other requests to the
> public DNS server (ip=88.146.135.10).
> Up to now everything worked fine.
>
>
> I discovered a problem with SRV request type from my Linux workstation
> (ip=192.168.15.207):
>
> $ nslookup -type=srv _xmpp-server._tcp.google.com
> ;; Warning: Message parser reports malformed message packet.
> Server:         192.168.15.20
> Address:        192.168.15.20#53
>
> *** Can't find _xmpp-server._tcp.google.com: No answer
>
>
> I monitored DNS traffic on my server using 'snoopy':
>
> 091714 ms
>        ether(s=6cf0490d4ac0 d=00270e03ef27 pr=0800 ln=88)
>        ip(s=192.168.15.207 d=192.168.15.20 id=5a54 frag=0000 ttl= 64 pr=17
> ln=74)
>        udp(s=44912 d=53 ck=a748 ln=  54)
>        dns(id=49429 flags=0x100)
>        dns.qd(srv name=_xmpp-server._tcp.google.com ttl=0)
> 091730 ms
>        ether(s=00270e03ef27 d=0013101df6b6 pr=0800 ln=88)
>        ip(s=192.168.15.20 d=88.146.135.10 id=f122 frag=0000 ttl=255 pr=17
> ln=74)
>        udp(s=40364 d=53 ck=6987 ln=  54)
>        dns(id=374 flags=0x100)
>        dns.qd(srv name=_xmpp-server._tcp.google.com ttl=0)
> 091755 ms
>        ether(s=0013101df6b6 d=00270e03ef27 pr=0800 ln=458)
>        ip(s=88.146.135.10 d=192.168.15.20 id=ad4c frag=0000 ttl=126 pr=17
> ln=444)
>        udp(s=53 d=40364 ck=6873 ln= 424)
>        dns(id=374 flags=0x8500)
>        dns.qd(srv name=_xmpp-server._tcp.google.com ttl=0)
>        dns.an(srv name=_xmpp-server._tcp.google.com ttl=900)
>        dns.an(srv name=_xmpp-server._tcp.google.com ttl=900)
>        dns.an(srv name=_xmpp-server._tcp.google.com ttl=900)
>        dns.an(srv name=_xmpp-server._tcp.google.com ttl=900)
>        dns.an(srv name=_xmpp-server._tcp.google.com ttl=900)
>        dns.ar(ip name=xmpp-server1.l.google.com ttl=1800)
>        dns.ar(ip name=xmpp-server4.l.google.com ttl=1800)
>        dns.ar(ip name=xmpp-server.l.google.com ttl=300)
>        dns.ar(ip name=xmpp-server2.l.google.com ttl=1800)
>        dns.ar(ip name=xmpp-server3.l.google.com ttl=1800)
> <after several seconds 'snoopy' inexplicably ends!>
>
>
> You can see that:
> - request is delivered from Linux to the server,
> - relayed to the public server,
> - answer is received from the public server,
> - nothing is sent to the Linux.
>
> This is not fully true, I monitored the IP traffic on Linux using
> 'wireshark'.
> Linux received an answer, but as a malformed (cut) packet.
> (Just note: This 'wireshark' dump does not match preciselly since the
> the 'snoopy' dump was from different test.
> But the behavior is always the same.)
>
> 0000  6c f0 49 0d 4a c0 00 27  0e 03 ef 27 08 00 45 00
> l.I.J..' ...'..E.
> 0010  01 25 53 db 00 00 ff 11  c6 b8 c0 a8 0f 14 c0 a8   .
> %S..... ........
> 0020  0f cf 00 35 cd c2 01 11  8f a0 53 4e 84 80 00 01   ...
> 5.... ..SN....
> 0030  00 05 00 00 00 00 0c 5f  78 6d 70 70 2d 73 65 72   ......._ xmpp-
> ser
> 0040  76 65 72 04 5f 74 63 70  06 67 6f 6f 67 6c 65 03
> ver._tcp .google.
> 0050  63 6f 6d 00 00 21 00 01  c0 0c 00 21 00 01 00 00
> com..!.. ...!....
> 0060  01 0a 00 20 00 14 00 00  14 95 19 78 6d 70 70
> 2d   ... .... ...xmpp-
> 0070  73 65 72 76 65 72 32 2e  6c 2e 67 6f 6f 67 6c 65   server2.
> l.google
> 0080  2e 63 6f 6d c0 0c 00 21  00 01 00 00 01 0a 00
> 20   .com...! .......
> 0090  00 14 00 00 14 95 19 78  6d 70 70 2d 73 65 72 76   .......x mpp-
> serv
> 00a0  65 72 33 2e 6c 2e 67 6f  6f 67 6c 65 2e 63 6f 6d   er3.l.go
> ogle.com
> 00b0  c0 0c 00 21 00 01 00 00  01 0a 00 20 00 14 00
> 00   ...!.... ... ....
> 00c0  14 95 19 78 6d 70 70 2d  73 65 72 76 65 72 34 2e   ...xmpp-
> server4.
> 00d0  6c 2e 67 6f 6f 67 6c 65  2e 63 6f 6d c0 0c 00 21
> l.google .com...!
> 00e0  00 01 00 00 01 0a 00 20  00 14 00 00 14 95 19
> 78   .......  .......x
> 00f0  6d 70 70 2d 73 65 72 76  65 72 31 2e 6c 2e 67 6f   mpp-serv
> er1.l.go
> 0100  6f 67 6c 65 2e 63 6f 6d  c0 0c 00 21 00 01 00 00
> ogle.com ...!....
> 0110  01 0a 00 1f 00 05 00 00  14 95 18 78 6d 70 70
> 2d   ........ ...xmpp-
> 0120  73 65 72 76 65 72 2e 6c  2e 67 6f 6f 67 6c 65 2e
> server.l .google.
> 0130  63 6f 6d
> com
>
>
> It seems to me the DNS in Plan9 has a problem... ;-)
>
> Can anyone help me?
>
> Thanks in advance.
>
> Pavel
>
>



-- 
С наилучшими пожеланиями
Жилкин Сергей
With best regards
Zhilkin Sergey