Wi-Fi Probe Request
Definition
A broadcast management frame that a Wi-Fi radio sends when scanning for known networks. The frame advertises the SSIDs stored in the device's preferred network list. Nearby access points or passive sniffers can log these frames with timestamps, providing evidence of physical proximity.
- Frame type
- Broadcast management frame
- Sent when
- Device scans for known networks
- Contents
- SSIDs from the preferred network list
- Forensic use
- Evidence of physical proximity via logged, timestamped captures
Common questions
Why do probe requests reveal information even if a device never connects to a network?+
The frame is broadcast to actively search for remembered networks, exposing the SSID list regardless of whether any access point responds, so a passive sniffer or nearby access point can log the device's presence without it ever joining a network.
Do modern devices still leak SSID lists through probe requests?+
Many current devices use randomised MAC addresses and directed rather than broadcast probing to reduce this exposure, so the evidentiary value of probe request logging depends on the device's OS version and privacy settings at the time.
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