3 ms·
At the driver level it's totally possible to do a purely passive scan that would be nearly impossible to detect, it's just not very practical so most OSes don't
by zwieback 13y ago
At the driver level it's totally possible to do a purely passive scan that would be nearly impossible to detect, it's just not very practical so most OSes don't even allow you to force your radio to do that.
I think there's s some theoretical possibility that you could "see" the absorption of the RF energy in the antenna of a purely passive device but I think that would be extremely hard unless you're in an RF shielded box.
I'd answer the question "it can be purely passive but it's not usually done that way", which the top SU answer also states.
- lcedp 13y agoThe technique is widely used for Wi-Fi sniffing. Indeed not all combinations of OSs/cards/drivers are supported.
- hershel 13y agoWhy is passive mode not practical?
- zwieback 13y agoBecause you never know how often the AP will broadcast it's SSID so the passive listener doesn't know how long to listen on any particular channel. In the case where the AP doesn't broadcast the SSID it's even worse, the passive listener relies on other clients actively scanning and the AP responding with its SSID.