Testing DTLS with the echo_client and echo_server samples #ble #nrf52832 #crypto

Stefan Hristozov

Hi all,

I want to test DTLS in IPv6 over BLE network.
My set up looks as follows:
                  BLE                                                                     wifi                        wifi
nrf52832 --------------------- Raspberry Pi Border router --------------- WIFI router --------------- PC
2001:db8::1                       2001:db8::2     2001:db9::1                                                  2001:db9::2

1) I compiled the echo_server with:

west build -- -DOVERLAY_CONFIG=overlay-bt.conf

and flashed it on an nrf52832 DK board. The board connects aimlessly with the border router.

2) In another terminal I compiled the echo_client for netive_posix:

west build -b native_posix,

I started the zephyrproject/tools/net-tools/net-setup.sh, and then the native_posix application with:

west build -t run.

3) In another terminal, I started tcpdump listening to the zeht interface. Unfortunately, I cannot see any packets send or received. The console output of the echo_client and echo_servers also does not indicate the something was send or received.

I want to test the sending and receiving of DTLS packets at the nrf52832 board in the three modes:
* Preshared Keys PSK
* Raw Public Keys RPK
* Certificates
I want to secure only UDP over IPv6 (No TCP and no IPv4).

My Questions are:
1) Is the described above procedure correct? I assume something is wrong otherwise I will see some exchanged packets with tcpdump and console output?
2) How to select the DTLS modes PSK/RPK/Certificates?
3) The echo_client and echo_server samples are very complex. Can you point me to a more simple example or describe the procedure for setting up a secured with DTLS UDP communication?

Best regards,

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