[Winpcap-users] target not receiving the packets

Fish fish at infidels.org
Fri Apr 18 17:24:59 GMT 2008

Hash: SHA1

chitra .R wrote:

> Hi all,
>     Thanks for your reply, I am framing the frame as
>   [dstmac addr + src mac addr + type + data], i tried the type as 
> 0x0800, still I am not able to capture the packet at the target. 
> I verified for both source and destination are on the same network.
>   Thanks,
>   Chitra

What is the packet payload? (the data?) An IP packet? Does it have a
correct checksum? What about TCP? Does it have a correct checksum? If
the payload (the data) is a TCP/IP packet then both the ip header and
the tcp header must both have a valid checksum or else the packet
will get rejected at the receiving end if receive checksum offloading
is enabled.

Check your adapter settings on the adapter you're trying to do the
capturing on. If receive checksum offloading is enabled on it, try
disabling it. Also, what is the size of the packet you're trying to
send? (including the 14 bytes (6+6+2) ethernet header overhead?)
AFAIK WinPCap will reject attempts to send packets longer than 1514
bytes, so if your TCP/IP packet (presuming that's what you're
sending) is larger than 1500 bytes then that too might explain why
you're never seeing it at the receiving end: because it's never
getting sent!

Hope that helps some.

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"Fish" (David B. Trout) - fish(at)infidels.org
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