The Promiscuous mode is a specific receive mode for network-technology devices such as wireless network cards. It is normally used for packet sniffing and bridged network for hardware virtualization. The frames include the MAC (Media Access Control) address of the hardware.
In this mode the device submits all incoming traffic to the network interface and transmits the data for processing to the operating system. Devices that use this mode can be combinations of switches and routers, network tester or even a normal computer with a connection to a network.
For Wireless LANs in promiscuous mode it will only forward the packets of the network (access points) to which the client is currently connected. The Promiscuous Mode is unsuitable to receive packages from a network which you do not own because you need to authenticate yourself with the network.
The opposite of this mode is the non-promiscuous mode. In this mode the unit handles only the packets addressed to it and this happens for example in Ethernet networks, the evaluation of the MAC address plus broadcast packets.
Another method of usage is to detect network connectivity issues. Some programs use this feature to show everything that is transferred by the network and some of them can transfer passwords and data in clear text. So a normal user should stay away of this mode to prevent that someone else could steal this data while the transferring process.
As you can see the Promiscuous Mode should only be used by advanced users to avoid any damage to your system or to open the door for hackers. But when you know what you are doing this mode is quite powerful and you can repair your network without any problem.
Of course not every wireless card drivers support this mode because of it’s not a secure mode. If you need this mode you should watch out for another driver that supports the Promiscuous Mode. You can contact your device’s manufacturer and ask for a new driver.
If you’d like to read more about the technology behind a Wireless Monitor or if you are interested in Wireless Monitor Adapters click one of the links above.