[Winpcap-users] winpcap captures packet, but winsock doesn't see it

[Coleman Brumley]

Hello all.

I have a strange problem and I was hoping someone could point me in the
right direction.

I have an issue where 2 IP endpoints are configured as 138.67.19.10 and
138.67.19.37 with subnet masks of 255.255.192.0.  They are connected via a
switch.  I'm not sure of the switch manufacturer.

Device A (a WinXP PC running a Winsock application) sends a UDP broadcast to
138.67.63.255.  Device B (an embedded device) replies to that broadcast with
another broadcast to 138.67.63.255.  Wireshark/Winpcap is running on the PC.
Wireshark captures the reply, but the reply doesn't get to the Winsock app
running on Device A.  It's like the app just never received the packet (i.e.
recvfrom doesn't indicate that any data has been received).  

I'm unable to duplicate this behavior in my similar environment, so
something tells me it's the PC in question or some other hardware issue
(something with the NIC driver?).  

Regards,
Coleman