TDI filter driver.

Hi,
I am trying to write a tdi filter driver. As I am not having any
experience in writing drivers, downloaded one sample filter driver
from sourceforge and started modifying that as per my requirement.
When I install this driver, I am seeing that for every UDP packet it
calls IRP_MJ_CREATE dispatcher but it never calls IRP_MJ_CLEANUP or
IRP_MJ_CLOSE. Is this an expected behavior? Or when does actually
these are dispatched?

Thanks,
Satyendra
.