Nedim Šabić has written a tutorial article on using the eXpress Data Path for fast packet filtering. "Now comes the most relevant part of our XDP program that deals with packet’s processing logic. XDP ships with a predefined set of verdicts that determine how the kernel diverts the packet flow. For instance, we can pass the packet to the regular network stack, drop it, redirect the packet to another NIC and such. In our case, XDP_DROP yields an ultra-fast packet drop."