Yes, ROS supports USB to ETH adapters and your use is exactly what they are good for. RTL8152/8153/etc adapters seems to be well supported, with exception of 8156 that may be supported soon (see http://forum.mikrotik.com/t/realtek-rtl8156-2-5g-usb-ethernet-for-ros7/155285/1). Just be aware there’s plenty of Chinese clones of these chips that are super unstable…