Net_Wifi uses the command line tools iwconfig and iwlist to gather information about local wireless network interfaces, and to give information about wireless networks reachable by your computer.
To work with the class, you need to make sure that both programs are found. By default, /sbin/ and /usr/sbin/ are looked up to find them when the class is instantiated. If that fails, the system's which tool is used to determine the location.
You can retrieve and set their locations with getPathIwconfig() and setPathIwconfig(), as well as getPathIwlist() and setPathIwlist().