[Nfd-dev] tcpdump rejecting ndn packets

[Ishita Dasgupta]

I am trying to investigate into the NDN interest/data packets. Seeing the
UDP tunnel packets on tcpdumpp doesn't really tell me anything other than
IP and packet size whereas on ndndump, I can see the interest msg+nonce
number+segment number, etc. Then, is it safe to assume that tcpdump will
not really tell me anything here?

Regards,
Ishita Dasgupta

*Graduate Student**College of Information and Computer Sciences*
*,UMass Amherst*


On Fri, Oct 4, 2019 at 1:31 PM Davide Pesavento <davidepesa at gmail.com>
wrote:

> 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
> >
> > _______________________________________________
> > Nfd-dev mailing list
> > Nfd-dev at lists.cs.ucla.edu
> > http://www.lists.cs.ucla.edu/mailman/listinfo/nfd-dev
>
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