I'd originally suggested fifos without puting a whole lot of thought into it. With Cushman's comment above about what happens when the listening process isn't running (IIRC, you just block for writing indefinintely?).

TCP sockets on the real interface sounds like an excellent idea... I like the being able to connect from other machines aspect.

What happens if the player's in DHCP mode and you're in-car? Is the interface still brought up just without an IP or is it down? Can you bind to it?