Hello,
we have come up with the similar problem once, but I need you to answer the following question to see if it's really the same situation:
Are MAC address in the ICMP packet really present in your network or are they something like DigitalEquipment_00-02-01 (one such is the source and one is the destination)?
Petr Vacha
> -----Original Message-----
> From: wireshark-users-bounces@xxxxxxxxxxxxx
> [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Jim Young
> Sent: Monday, August 28, 2006 5:25 PM
> To: wireshark-users@xxxxxxxxxxxxx
> Subject: Re: [Wireshark-users] Ping Replys without Request
>
> Hello Michael,
>
> >>> "STEINECKE Michael SD-G (AREVA NP GmbH)"
> <Michael.Steinecke@xxxxxxxxx> 08/28/06 4:33 AM >>>
> > Hello folks,
> >
> > i've a bit strange issue in the communication between a Server and
> his
> > client (a microcontroler).
> > The controler send "Echo Reply" packets without a corresponding
> ICMP
> > requests. Is there another way how this can happen then an program
> or
> > firmware error? Something like an TCP packet that requests a ICMP
> Echo
> > par example?
> >
> > Best Regards
> > Michael Steinecke
>
> Does you controller have multiple NIC interfaces? If so, then
> depending on how you've set up your route statements on
> the controller (assuming that you can) it's possible that replies
> received on one NIC interface will be returned out a different
> NIC interface. IP addresses more than one hop away could
> be taking a "default" route (out the NIC interface towards
> your server).
>
> Take a look at the destination IP address (where the ping reply
> is supposed to go to) and the destination MAC address for the
> ping reply. This should give you a clue on who/what might be
> generating the original request.
>
> Then again if it's some type of specialized controller, then I
> wouldn't be surprised to see the vendor doing something
> non-conventual like using ICMP echo replies to send signalling
> information to some other station(s).
>
> I've also seen some devices that use an an undocumented
> private NIC setup internally. I've had a few occasions where
> these back-end packets have leaked out the one public NIC.
>
> I hope this find this useful.
>
> Jim Young
>
>
>
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