>I want to try out this API function:
>
>ULONG WINAPI GetAdaptersAddresses(
> _In_ ULONG Family,
> _In_ ULONG Flags,
> _In_ PVOID Reserved,
> _Inout_ PIP_ADAPTER_ADDRESSES AdapterAddresses,
> _Inout_ PULONG SizePointer
>);
>
>How do I use that in VFP?
>
>See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365915(v=vs.85).aspx for more detail

If restricted to Vista and upwards, you may consider this alternative:

CLEAR

LOCAL WMIService, AllNetworkAdapters, NetworkAdapter, MACAddress

m.WMIService = GETOBJECT("winmgmts:\\.\root\cimv2")

m.AllNetworkAdapters = m.WMIService.ExecQuery("Select * from Win32_NetworkAdapter",,48)

FOR EACH m.NetworkAdapter IN m.AllNetworkAdapters
	m.MACAddress = m.NetworkAdapter.MACAddress
	IF !ISNULL(m.MACAddress)
		? m.NetworkAdapter.name + ": " + m.MACAddress + " (" + IIF(m.NetworkAdapter.PhysicalAdapter,"","not ") + "physical)"
	ENDIF
ENDFOR

Complete set of properties at https://msdn.microsoft.com/en-us/library/aa394216(v=vs.85).aspx