[Winpcap-users] Capture fails in pppoe enviroment

Kyle Brotheridge kyle at connecttel.com.au
Tue Jun 1 15:42:44 PDT 2010


Lesher,

If you set no filter (So all packets comes through) in your program, do any packets get captured on the VPN interface?

-KB

From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of ceo at triplebit.com
Sent: Wednesday, 2 June 2010 7:32 AM
To: winpcap-users at winpcap.org
Subject: Re: [Winpcap-users] Capture fails in pppoe enviroment

Tahnks KB,
I followed your advise but still encountered problems capturing the "PPP Interface that the PPPoE terminates on". Using Wireshark I did see the packets when using no filtering. I couldn't filter them nor with the port (8081 in this case) and nor with the type which is UDP.
Since my code also uses filtering that explains why my code dosn't capture either.
So my question is now why can I see the packets if I don't filter(but if I watch them later I can see the UDP and the port which is 8081) but if I try to filter with the type or the port I don't see any packet?
Regards
I. Lesher
----- Original Message -----
From: Kyle Brotheridge<mailto:kyle at connecttel.com.au>
To: ceo at triplebit.com<mailto:ceo at triplebit.com> ; winpcap-users at winpcap.org<mailto:winpcap-users at winpcap.org>
Sent: Monday, May 31, 2010 3:58 AM
Subject: **SPAM** RE: [Winpcap-users] Capture fails in pppoe enviroment

Lesher,

Please explain a bit more. From my understanding you have a PC connected to a LAN, and a PPPoE connection terminating on the same PC via its local NIC.

You CAN capture LAN traffic, but CANNOT capture traffic from the PPPoE connection?

From this I’d say it’s because the packets from the PPPoE are encapsulated in PPP/GRE, if you’re looking to capture the packets contained within the PPP stream, you’ll have to capture on the PPP Interface that the PPPoE terminates on.

-KB

From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of ceo at triplebit.com
Sent: Saturday, 29 May 2010 7:21 PM
To: winpcap-users at winpcap.org
Subject: [Winpcap-users] Capture fails in pppoe enviroment

Hi all,
I use WinPcap 4.02 to capture stream source and to process the data somehow.
It works fine if the source is inside a LAN.
On the other hand, when source is in a pppoe Internet connection, I capture the Ethernet card that supports the Internet connection and I get no packet captured.  The following while loop simply never enters the loop as it does in a LAN environment.

while((res = pcap_next_ex( adhandle, &header, &pkt_data)) >= 0)

{

if(res == 0)

/* Timeout elapsed */

continue;
However in a Wireshark I can definitely see the expected packets om this same card.
The algorithm is similar in both environments and it based on the samples following the product.
Has anyone any idea what could be the cause?
Regards
I. Lesher
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