Windows 7 (or 10) is unable to open the 192.168.123.123 with USB connection
It is possible that the USB Ethernet RNDIS Gadget driver is missing, see below picture.
For Windows 7, see here how to find the correct driver:
http://developer.toradex.com/knowledge-base/how-to-install-microsoft-rndis-driver-for-windows-7
The Windows 10 reports the USB-to-Ethernet-device as USB-serial port on the Control panel. In this case the driver needs to be updated. First download the driver from below:
Then in Control Panel use right mouse click on the USB-serial port and select update driver and select option to "seek driver from your computer" and select "disk" and "browse file" to choose above INF-file to update the device driver software.
If Windows 10 refuses to install the INF-file because of it is not signed file, then do as described in this page to disable the driver signature enforcement and install the driver:
https://www.maketecheasier.com/install-unsigned-drivers-windows10/
Also this youtube video shows how to disable signature enforcement so that you will be able to install the driver:
After the successful driver installation you should be able to "ping 192.168.123.123" if USB cable is connected to the controller board.