Hi Sake,
Thanks for your reply.
I am using pcap and loop through the packets. How can I check that all
outgoing packets from that host will have a bad TCP checksum?
And how common is it that the capturing has TCP checksum offloading? I
receive many pcap files from clients and have no way to find out.
Thanks,
Andrej
On Wed, May 26, 2010 at 4:53 PM, Sake Blok <sake@xxxxxxxxxx> wrote:
> On 26 mei 2010, at 08:06, Andrej van der Zee wrote:
>
>> I was wondering if there is any way to deduct the local IPs from
>> TCP/IP packets in pcap files? IP packets contain src and dst fields,
>> but as far as I can see it is impossible to know which IP is bound to
>> the host where the pcap file is generated.
>
> If the host that was capturing has:
>
> 1) TCP checksum offloading *and*
> 2) Was sending TCP packets during the capture
>
> Then all outgoing packets from that host will have a bad TCP checksum (because the packets were captured before the NIC could change the checksum value to the proper value).
>
> Cheers,
>
>
> Sake
>
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