After an admittedly cursory examination of Socket, I see only
the comment of:

        The netType parameter is platform dependent and can be used to
        encode both the protocol type (IP, Xerox XNS, etc.) and/or the
        physical network interface to use if this host is connected to
        multiple networks. A zero netType means to use IP protocols
        and the primary (or only) network interface.

in Socket>>primSocketCreateNetwork:type:receiveBufferSize:sendBufSize:semaIndex:

Has anyone done any work to document how this works for the various
platforms, or try to make this a little more portable?

Specifically, I need this to bind to a particular interface on a Linux
box for my ISP.

It looks like sqUnixSocket.c ignores that parameter, creating
an INADDR_ANY socket every time.

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