Got bad packet: bad label type

Kevin Darcy kcd at chrysler.com
Wed Oct 22 02:44:07 UTC 2008


Linux Addict wrote:
> On Tue, Oct 21, 2008 at 6:24 PM, Mark Andrews <Mark_Andrews at isc.org> wrote:
>   
>> In message <707abafb0810211024m2d1a3e55j5d495433db242217 at mail.gmail.com>,
>> "Linu
>> x Addict" writes:
>>     
>>> I get this error when I try resolve some specific records. Anyone know
>>>       
>> what
>>     
>>> it means and how to resolve it.
>>>       
>>         You got a malformed packet.
>>
>>     
>>> ;; Got bad packet: bad label type
>>> 160 bytes
>>> 2b 3c 81 80 00 01 00 04 00 00 00 00 09 5f 6b 65
>>>       
>>   id=11068
>>              questions=1
>>                    answers=4
>>                          authorityu=0
>>                                additional=0
>>                                         _kerberos.
>>     
>>> 72 62 65 72 6f 73 04 5f 75 64 70 05 49 54 57 45
>>>       
>>                        _tcp.          ITWEB.
>>     
>>> 42 05 57 45 42 4d 44 03 4e 45 54 00 00 21 00 01
>>>       
>>         WEBMD.            CET.        SRV   IN
>>     
>>> c0 0c 00 21 00 01 00 00 00 77 00 10 00 00 00 64 <------------------\
>>>       
>>  compression point to offset 0x0c (_tcp.ITWEB.WEBMD.CET.)           |
>>        SRV   IN    119         16    0     100                      |
>>     
>>> 00 58 07 64 6e 79 64 63 30 32 c0 3f c0 0c 00 21                    |
>>>       
>>   88       dnydc02.             compression pointer to offset 3f ----/
>>                         (which is 0x64, which is not a valid label).
>>     
>>> 00 01 00 00 00 77 00 10 00 00 00 64 00 58 07 64
>>> 6e 79 64 63 30 31 c0 3f c0 0c 00 21 00 01 00 00
>>> 00 77 00 10 00 00 00 64 00 58 07 64 6e 6a 64 63
>>> 30 32 c0 3f c0 0c 00 21 00 01 00 00 00 77 00 10
>>> 00 00 00 64 00 58 07 64 6e 6a 64 63 30 31 c0 3f
>>>
>>> Thanks
>>> LA
>>>
>>>
>>>
>>>       
>> --
>> Mark Andrews, ISC
>> 1 Seymour St., Dundas Valley, NSW 2117, Australia
>> PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org
>>
>>     
>
>
> This is awesome!! How did you decode it? Now How do I fix it?
>
>   
Well, the Message Format and Resource Record format are described in RFC 
1035, and ASCII is, well, ASCII.

How do you fix it?

Are you seeing this from a BIND nameserver?

If so, then there is presumably something in the middle corrupting the 
packet (not that I think BIND is perfect, but if it had a problem with 
basic packet construction I think we would have heard about it by now). 
Find out what that middlebox is and complain to the administrator/vendor.

If it's from some non-BIND nameserver, then go complain to the implementor.

                                                                         
                     - Kevin



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