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How Can I sniff GATT Service or Characteristic Attributes by PCA10031 (NRF51 Dongle)?

Daniel T. Lee

By using ble-sniffer, I success to catch BLE Advertising packet with my NRF51 Dongle in CMD and WIRESHARK either.
But, I can't sniff any other packet except type of ADV_IND, ADV_SCAN_IND, SCAN_REQ.SCAN_RSP and some of Unknown (CRC Incorrect Packet).

Does This NRF51 and this BLE_SNIFFER program can catch GATT Service or Characteristic? I tried to catch the values between GATT_Client and GATT_Server's communication.

During Capturing packet, I tried NRF51_DK's BLE_pheripheral, BLE_Central APP_Uart Example.
Sending lots of characters between two DK Boards, and also double checked with my Serial Monitor whether the characters were sent correctly.
But as my trial of all these stuff, I COULD NOT FIND MY ANY OF GATT Service or Characteristic Attributes.

Does NRF51 Dongle can sniff all of these data? Or it's just me that i can't snitch these packets?

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  • 0

    Hi Daniel,

    I'm afraid this is misunderstanding how BLE works. There are 3 dedicated channels for so-called advertising/scanning packets (typically in GAP Broadcaster and Scanner roles). This is what you see by default. All other PDU types and upper layers (LL, L2CAP, Security Manager, ATT, GATT) can be observed only during connection so the answer to your question is simpl: you either don't have any connection (so nothing to observe) or your sniffer misses it (or is wrongly configured so it doesn't follow particular "master" after CONNECT_REQ packet). I can ensure you that nRF51 DONGLE as well as nRF51 DK with Nordic BLE sniffer FW can capture all these packet types.

    Cheers Jan

  • 0 in reply to endnode

    I'm really sorry for bothering you, but i tried it also....

    The only diffrence between selecting device and non-selecting device is, when I turn on Wireshark with it, It just captures the packet of the selected device.

    Yes, it's a proper action with just print out the selected device's packet, but it keeps prints out BLE_ADV. Cause, The device that I selected from the "FIGURE 4" is peripheral not actually had any connection. So, It keeps sending out advertising packet.

    But actually the thing that i want is, It's GATT DATA PACKET, which sends out after a connection is established. I thought "FIGURE 4" 's selecting device is same action to connecting to board, but It wasn't. (Cause the device is keep sending out just ADV Packet.)

    This device has this connectability. (Double checked with my Master Control Panel)

    Advertising Type: Connectable

    BrEdrNotSupport

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  • 0 in reply to endnode

    I'm really sorry for bothering you, but i tried it also....

    The only diffrence between selecting device and non-selecting device is, when I turn on Wireshark with it, It just captures the packet of the selected device.

    Yes, it's a proper action with just print out the selected device's packet, but it keeps prints out BLE_ADV. Cause, The device that I selected from the "FIGURE 4" is peripheral not actually had any connection. So, It keeps sending out advertising packet.

    But actually the thing that i want is, It's GATT DATA PACKET, which sends out after a connection is established. I thought "FIGURE 4" 's selecting device is same action to connecting to board, but It wasn't. (Cause the device is keep sending out just ADV Packet.)

    This device has this connectability. (Double checked with my Master Control Panel)

    Advertising Type: Connectable

    BrEdrNotSupport

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