[Winpcap-users] problem with pcap_packetsend

Horatio horatio at rtlab.cs.nthu.edu.tw
Wed Nov 1 17:14:42 GMT 2006

Gianluca Varenni,

I think you are right. Thank you very much.
I forgot the limit of Ethernet frame size......I'm such an idiot!

The computer in private network sends a frame with 1514bytes (sent by
MSN Messenger, a TCP segment of a reassembled PDU),
and then I add the PPPoE/PPP header. Now the frame is 1522bytes.

But the MSN Messenger on the computer which directly access Internet on
PPPoE, that frame is 1502bytes including PPPoE/PPP header.
MSN is so smart to detect it and adjust the frame size!? How did it do this?

How can I overcome this problem? This problem is solved if the computer
in private network never sends frame whose size is larger than, say 1506
or 1494.

Gianluca Varenni 提到:

> Horatio,
> 1514 is the maximum frame size (excluding the Frame Check Sequence)
> that you can transmit on an ethernet adapter. That's probably the
> reason why pcap_packetsend fails.
> Hope it helps
> GV
> ----- Original Message ----- From: "Horatio"
> <horatio at rtlab.cs.nthu.edu.tw>
> To: <winpcap-users at winpcap.org>
> Cc: <horatio at rtlab.cs.nthu.edu.tw>
> Sent: Wednesday, November 01, 2006 5:36 AM
> Subject: [Winpcap-users] problem with pcap_packetsend

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