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

[Coleman Brumley]

Thank you for your response.  

It turns out it was a software firewall issue.  Very strange since the
firewall claimed to "block UDP broadcasts", but *only* blocked them on the
255.255.192.0 subnet.  If we changed the mask to 255.255.255.0, then it
wasn't being blocked.  

- Coleman


> -----Original Message-----
> From: Gianluca Varenni [mailto:gianluca.varenni at cacetech.com]
> Sent: Wednesday, January 07, 2009 2:42 PM
> To: coleman.brumley at jandasoft.biz; winpcap-users at winpcap.org
> Subject: Re: [Winpcap-users] winpcap captures packet, but winsock
> doesn't see it
> 
> It's definitely not a NIC issue. The TCP/IP protocol driver is
> rejecting
> that packet for some reason that doesn't come to my mind at the moment.
> 
> What is the MAC src and destination addresses that you are using?
> 
> GV
> 
> ----- Original Message -----
> From: "Coleman Brumley" <coleman.brumley at jandasoft.biz>
> To: <winpcap-users at winpcap.org>
> Sent: Tuesday, January 06, 2009 1:47 PM
> Subject: [Winpcap-users] winpcap captures packet, but winsock doesn't
> see it
> 
> 
> > 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
> >
> >
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