[Planetlab-users] question on tcpdump on new system

[Sapan Bhatia]

Hi Ning,

This is a known issue. You are the first person to report a blocked
application because if it. I'll look into this.

Which ICMP type are you using for the probes? Destination-port unreachable?

This behavior seems to have changed in the mainline kernel, because we
don't see these packets appear even with the PlanetLab extensions
turned off. If you know of any configuration changes you can make to
get these packets to show up, then please let us know. I'll look
around too.

Sapan

On Mon, Jul 7, 2008 at 5:03 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
>>>
>>
>