Here, finally, I have the miracle solution. I plugged this "hub" on my computer and I immediately had provided additional 7 USB ports. As I have an external hard drive, I plugged in this hub on the sector: a transformer is provided (a pleasant surprise). If you do not need external hard drive, if you use the right hub for mice, keyboards and small appliances, a priori, there is no need to plug it.
Beware, however, because the usb cable to connect the hub to the computer is female / female (so to speak) so do not lose it or risk having to buy another.
Ultimately, a great way to get additional USB ports cheaply and especially it's plug and play. no need to install any software: it is childish.