Netgraph question

[Aziz Kezzou]

Hi all,
I worked a bit with netgraph nodes and I find them very amazing and
powerfull... Since my netgraph experience is still quite limited (
they are out of the scope of my project actually) I would like to know
if the following claim is true, I need to be sure because it is for my
master thesis ;-) :

"Negraph nodes allow us, theoritically, to "steal" and inject packets
of _any_ type from/at _any_ level of the network subsystem"

Thanks,
-aziz