[Udpcast] updcast packet capture issue

Jayen jayenashar at gmail.com
Sun Oct 6 02:03:44 CEST 2013


Do you have a switching loop?  (I guess if you found it, you'd have already
addressed it.)
On Oct 6, 2013 10:34 AM, "Chris Healy" <cphealy at gmail.com> wrote:

> No, it's a wired network with a known flaw that leads to temporary packet
> storms of up to a second or so.  (We are working on addressing this network
> flaw, but it seems to have exposed a vulnerability within this application.)
>
>
> On Sat, Oct 5, 2013 at 4:27 PM, Jayen <jayenashar at gmail.com> wrote:
>
>> is it over Wi-Fi? There may be retransmissions, but they haven't caused
>> me any issues.
>> On Oct 6, 2013 10:06 AM, "Chris Healy" <cphealy at gmail.com> wrote:
>>
>>> Jayen,
>>>
>>> Thank you.  You were correct.  I no longer have this problem.  I also
>>> deduced that there is a sequence number in the multicast frame.
>>>
>>> I'm digging into this utility as I currently have a scenario where I get
>>> a bunch of duplicate frames hitting the udp-receiver (network issue, not
>>> application issue) and the application does not gracefully handle it.  I
>>> figured that the application did not have a sequence number.  As it does,
>>> there must be some other problem.  More to come.
>>>
>>> Chris
>>>
>>>
>>> On Sat, Oct 5, 2013 at 3:55 PM, Jayen <jayenashar at gmail.com> wrote:
>>>
>>>> I believe wireshark is trying to decode it as a different protocol
>>>> which encapsulates IP in UDP.  Try disabling it.
>>>> On Oct 6, 2013 6:02 AM, "Chris Healy" <cphealy at gmail.com> wrote:
>>>>
>>>>>  Alain,
>>>>>
>>>>> I'm trying to perform a packet capture of the data transmitted by
>>>>> udp-sender using Wireshark and am running into the exact same problem
>>>>> encountered by Lance 8 years ago.  (posting listed below.)
>>>>>
>>>>> What information can I provide to help debug this issue?
>>>>>
>>>>> Also, can you tell me if the multicast data sent includes a sequence
>>>>> number and does the receiver have the ability to filter out duplicate
>>>>> multicast frames?
>>>>>
>>>>> Regards,
>>>>>
>>>>> Chris
>>>>>
>>>>>
>>>>>
>>>>> On Mon 8/15/2005 10:25 AM, Alain Knaff wrote:
>>>>> >*Try upgrading to a newer version of ethereal.*>**>*I just tried it
>>>>> here: version 0.10.9 has the problem, but 0.10.12*>*works fine.*>**>*Or use
>>>>> tcpdump...*
>>>>>
>>>>> I have used the lattest version of udpcast (udpcast-20050226.tar.gz)
>>>>> as well as used ethereal version 0.10.12 and
>>>>> I still get the "Bogus IP header length (0, must be at least 20)" I
>>>>> will continue to try this on different Platforms with different
>>>>> network switches and see what I get.
>>>>>
>>>>> -Lance
>>>>> _______________________________________________
>>>>> Udpcast mailing list
>>>>> Udpcast at udpcast.linux.lu
>>>>> https://www.udpcast.linux.lu/cgi-bin/mailman/listinfo/udpcast
>>>>>
>>>>
>>>
>



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