[9fans] DNS problem

[9fans] DNS problem

[Pavel Klinkovsky]

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

Re: [9fans] DNS problem

[Sergey Zhilkin]

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

Re: [9fans] DNS problem

[Pavel Klinkovsky]

On 23 lis, 10:48, Pavel Klinkovsky <pavel.klinkov...@gmail.com> wrote:
>         dns.ar(ip name=xmpp-server2.l.google.com ttl\x1800)
>         dns.ar(ip name=xmpp-server3.l.google.com ttl\x1800)
> <after several seconds 'snoopy' inexplicably ends!>

Interesting, I checked the 'status' after the 'snoopy' failure:
snoopy 28077: Killed: Insufficient physical memory

Pavel

Re: [9fans] DNS problem

[erik quanstrom]

On Tue Nov 23 12:33:37 EST 2010, pavel.klinkovsky@gmail.com wrote:
> > i can't replicate this now.  not saying you don't have
> > a problem, just that i can't replicate this right now.
> Interesting.
> Some mistake in my NDB configuration?

i think it's a real data-dependent bug in dns, not
a configuration error.  i'm sure google's srv records
are not static.

- erik

Re: [9fans] DNS problem

[Pavel Klinkovsky]

> i can't replicate this now.  not saying you don't have
> a problem, just that i can't replicate this right now.
Interesting.
Some mistake in my NDB configuration?

Pavel

Re: [9fans] DNS problem

[erik quanstrom]

> 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 can't replicate this now.  not saying you don't have
a problem, just that i can't replicate this right now.

- erik