Hi All,

I'm actually trying to write a test case to demonstrate
the problem in a repeatable way.

I first looked at socket(PF_INET, SOCK_RAW) to inject the
packets but it appears I have no control over the IP
checksum, and an invalid UDP sum didn't cause any problems
(the packet was accepted fine).

So i've hacked up something with socket(PF_PACKET, SOCK_RAW)
but the problem i'm getting (although tcpdumps of the packets
look perfect), they are not being accepted by my UDP listening
socket. It uses real interfaces, not loopback for the raw
packet injection as the checksumming appears to be bypassed
on the loopback interface (I always see bad UDP checksum
on normally originated packets on the loopback interface).

Anyway, i've probably done something dumb. Anyone care to look
at my test code? The current code sends the packets out on all
interfaces (using the correct associated IP and MAC). Can change
the #if in main() to make it use normal UDP not my cooked packets
(which currently have correct checksums).

~mc