The .2mg image format contains a header which is missing from our file. So our file is rather a .po image.
I opted to not add the .2mg header as it is only necessary if the metadata it contains differs from the values "guessed" when using the "naked" .po image format. On the other hand there are image file consumers not understanding the .2mg image format.
Better match user expectations by allowing to download plain disk images and configure the IP settings afterwards on the target machine - then most likely leveraging DHCP. This works for the users with the most usual Ethernet adapter and settings - which are now pre-configured in default.cfg's. Only the few users with non-default Ethernet adapter and/or settings are required to download a custom contiki.cfg and inject it manually into their disk image files.
