[Nfd-dev] tcpdump rejecting ndn packets

[Davide Pesavento]

0x8624 is the NDN ethertype. If you're using UDP tunnels (i.e. NDN
over UDP/IP) then you're not going to see 0x8624, but you will see
0x0800, the IPv4 ethertype.

Davide

On Fri, Oct 4, 2019 at 1:24 PM Ishita Dasgupta via Nfd-dev
<nfd-dev at lists.cs.ucla.edu> wrote:
>
> tcpdump -i eth1 host 173.16.1.2 and port 6363 and ether proto 0x8624 -vvv
> OUTPUT: tcpdump expression rejects all packets
> WHEREAS
> tcpdump -i eth1 host 173.16.1.2 and port 6363 and ether proto 0x0800 -vvv
> OUTPUT: I do see UDP packets of type 0x0800 (only thing running on the eth1 interface at this point are ndnping pings)
>
> Any other tcpdump on eth1 shows ONLY the udp traces and no ndn traces (with or without above filters).
>
> Regards,
> Ishita Dasgupta
>
>
>
> On Fri, Oct 4, 2019 at 1:17 PM Junxiao Shi <shijunxiao at email.arizona.edu> wrote:
>>
>> Hi Ishita
>>
>> What's exact tcpdump command line you are trying to use?
>>
>> Yours, Junxiao
>>
>> On Thu, Oct 3, 2019 at 4:29 PM Ishita Dasgupta via Nfd-dev <nfd-dev at lists.cs.ucla.edu> wrote:
>>>
>>> Hi All,
>>> I have a docker that runs nfd 0.6.1 and has a route to its host over UDP and ethernet interface, say, eth1.
>>> I am trying to capture tcpdump (version 4.9.2) packets hoping to see NDN packets while ndnping runs in background. I can only see 0x0800 type packets but no 0x8624 packets.
>>> If I explicitly add filter to tcpdump to look for UDP port 6363 packets over eth1 and type 0x8624, I see: tcpdump: expression rejects all packets
>>> Interestingly if I am performing the same thing on the host machine, I can observe packets of type 0x8624.
>>> Has anybody come across this or has an idea why this happens?
>>>
>>> Regards,
>>> Ishita Dasgupta
>
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