There isn't. The problem is/was to write portable code for low level emulation. However, there is an idea to do high level emulation of networking by making a virtual device that implements the UNAPI software interface.
A high level UNAPI implementation would be nice, but unfortunately it wouldn't help for my use case (I want to write a network driver for Fuzix).
It looks like raw sockets would be quite easy way to do this, but of course that doesn't work on Windows...
QEmu seems to have solved the issue using SLIRP, maybe that could also be an option for OpenMSX.
geijoenr: AFAIK most modern Ethernet cartridges have a built in chip that manages the networking stuff. Not sure how that would have to be implemented in a low level way without going totally overkill.
Glad to hear Fuzix is still alive! Is the MSX port still working?
There isn't. The problem is/was to write portable code for low level emulation. However, there is an idea to do high level emulation of networking by making a virtual device that implements the UNAPI software interface.
So, it mean, what MIDI-NETWORK support never appear in OpenMSX?
It’s a pity, because it was the only real way to organize a real PC network connection with machines like 805 & 503.
maybe someone could write an external program that connects to the internet and uses the communication capability with openMSX to use a data pipe to read/write data?
I am trying to find an ethernet cartridge in the meantime. 
