Since the signals may travel a short distance outside the user's residence or business, like many other
home networking technologies, HomePlug includes the ability to set an encryption password. As with many other networking products, most HomePlug devices are "
secure by default". The HomePlug specification requires that all devices are set to a default out-of-box password—although a common one. Users should change this password.
To simplify the process of configuring
passwords on a HomePlug network, each device has a built-in master password, chosen at random by the manufacturer and
hard-wired into the device, which is used only for setting the encryption passwords. A printed label on the device lists its master password.
Taken from
wiki
So you can secure it
