We describe how the FreeBSD kernel was extended to facilitate multihoming and network mobility for UDP and TCP without changing the sockets API. Our solution -- the Identifier-Locator Network Protocol (ILNP) -- is an evolution of IPv6 that only requires updates to end systems. We show unmodified applications using the modified kernel to benefiting from network-layer mobility and multihoming over the global IPv6 Internet without requiring the cooperation or knowledge of ISPs, or modifications to existing infrastructure.