[Planetlab-users] question on tcpdump on new system

[Sapan Bhatia]

> One more thing, when I change the TCP packet to UDP packet (all using
> raw socket to send), I can get the reply packet.

Ok, this limits the issue to TCP then, as has been previously reported.

Sapan


> thanks!
> Ning
>
> On Mon, Jul 7, 2008 at 2:03 PM, Ning Qu <quning at ymail.com> wrote:
>> Hi Sapan,
>> Thanks a lot for your reply. My actual problem is like this: I have a
>> TCP-based customized ping program. The program uses raw socket to
>> create a TCP packet and sends to the high port of the destination. It
>> worked fine previously in the old system. But after upgrade, it cannot
>> receive the returned packets. I am certain there is replied packets
>> sent back from the other end. But the program receives nothing. Have
>> you seen this problem before? Is there any difference I should be
>> aware of for using the raw socket  in the new system?
>>
>> thanks!
>> Ning
>>
>>
>> On Mon, Jul 7, 2008 at 1:21 PM, Sapan Bhatia <sapanb at cs.princeton.edu> wrote:
>>> Hi Ning,
>>>
>>> Your slice only sees packets that belong to it. If you ping another
>>> host from within your slice, then the packets will appear in tcpdump.
>>> In this case, the packets belong to the administrative context of the
>>> system (and not your slice), so they are not reported via tcpdump.
>>>
>>> Sapan
>>>
>>> On 7/7/08, Ning Qu <quning at ymail.com> wrote:
>>>> Hi, I have problems receiving packets using raw socket recently (after
>>>>  system upgrade). The packets are sent back based on tcpdump on the
>>>>  sender site, but no packets captured on planetlab's tcpdump. For
>>>>  example, I am pinging one plnode from my own machine, and I do see the
>>>>  reply:
>>>>
>>>>  64 bytes from planetlab-9.CS.Princeton.EDU (128.112.139.108):
>>>>  icmp_seq=1 ttl=53 time=32.1 ms
>>>>  64 bytes from planetlab-9.CS.Princeton.EDU (128.112.139.108):
>>>>  icmp_seq=2 ttl=53 time=32.6 ms
>>>>
>>>>
>>>>  but on planetlab node I received nothing from tcpdump:
>>>>
>>>>  @planetlab-9 ~]$ sudo /usr/sbin/tcpdump
>>>>  tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
>>>>  listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
>>>>
>>>>  0 packets captured
>>>>  0 packets received by filter
>>>>  0 packets dropped by kernel
>>>>
>>>>  Can anyone help me on that?
>>>>  thanks
>>>>
>>>>  _______________________________________________
>>>>  Users mailing list: Users at lists.planet-lab.org
>>>>  https://lists.planet-lab.org/mailman/listinfo/users
>>>>
>>>
>>
>