node is both a netgraph node and a system networking interface.
node is created, a new interface appears which is accessible via
node interfaces are named
When a node is shutdown, the corresponding interface is removed
and the interface name becomes available for reuse by future
nodes; new nodes always take the first unused interface.
The node itself is assigned the same name as its interface, unless the name
already exists, in which case the node remains unnamed.
node has a single hook corresponding to each supported protocol.
Packets transmitted via the interface flow out the corresponding
Similarly, packets received on a hook appear on the interface as
packets received into the corresponding protocol stack.
The currently supported protocols are IP and IPv6.
node can be configured as a point-to-point interface or a broadcast interface.
The configuration can only be changed when the interface is down.
The default mode is point-to-point.
nodes support the Berkeley Packet Filter (BPF).