How does ble sniffing works?

[rajeshdubey293]

Is it possible to sniff the data between two device that already connected if yes then how if no why?. What are other method for sniffing oob and passkey security based devices? 

[ovrebekk]

Hi

If two devices are running an encrypted link you need to sniff the entire pairing procedure in order to be able to sniff the communication in later connections. If you just start sniffing after the link is encrypted you will not be able to sniff anything. 

Are you planning to use the Nordic sniffer, or one of the professional sniffers from Ellisys, Frontline etc?

Best regards
Torbjørn

[rajeshdubey293]

I have nrf51 dongle as well as nrf52840DK. I am trying to sniff some of the ble devices such as heart rate, ecg, battery monitor etc.for some of the device i am able to sniff but for some the device it is not possible, i am getting encrypted value. Is there anything to decode those values.

[ovrebekk]

Hi 

What kind of devices are these?

If these are off the shelf devices that you don't have debug access to then you might not be able to decrypt them (which is the point of the encryption obviously). 

But if they only use legacy Bluetooth pairing, and you pair them while the sniffer is active, then you should be able to sniff the communication. 

Best regards
Torbjørn