No possibility to select eth0 interface instead of wlan0

[pschmit86]

When wlan0 exists (without vp) that interface is selected by default. In case communication shall pass through usb connected eth0 interface the wlan0 needs to be switched off before starting application.

It might happen that wlan is used for other applications and cannot be switched off before starting atak.

It shall be possible to define the prefered netinterface. (Ranking)

See NetworkUtils.Java