Implement RFC 7217: "A Method for Generating Semantically Opaque

Implement RFC 7217: "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address Autoconfiguration."

"An IPv6 address configured using this method is stable within each
subnet, but the corresponding Interface Identifier changes when the
host moves from one network to another. This method is meant to be an
alternative to generating Interface Identifiers based on hardware
addresses."

OK naddy, sthen