MQTT Example - About Broker's IP

[MANGO]

Hi, I use the following.

• Raspberry Pi 3 (RPi3 with Raspbian Jessie 4.4) as a router,

RPi3 is connected to a Wi-Fi router to access the Internet by using the built-in Wi-Fi BLE BCM43438 chip.

• IoT SDK 0.9

• MQTT Publisher Example

• PCA10040 v1.1

• Keil MDK 5

• Amazon EC2 for Mosquitto Broker (v 1.4.9)

I downloaded the MQTT publisher example and with Keil, the code was loaded to the PCA10040 successfully.

I also installed radvd and Distributed a global IPv6 prefix.

I did connect the PCA10040 and the RPi3; I observed that the LED 1 stopped blinked after typing this.

# Connect to the device.
echo "connect 00:AA:BB:XX:YY:ZZ 1" > /sys/kernel/debug/bluetooth/6lowpan_control

(Followed this link)

However, the LED didn't change when I pressed Button 1.

In other words, the publishing has failed.

static const ipv6_addr_t               m_broker_addr ={
.u8 =
{0x20, 0x01, 0x0D, 0xB8,
 0x00, 0x00, 0x00, 0x00,
 0x00, 0x00, 0x00, 0x00,
 0x00, 0x00, 0x00, 0x01}};

The example used this IPv6 broker address.

As far as I know, the Amazon EC2 instances do not support IPv6.

/+++++++++++++++++++++++++++++++++++++++++++++++++/

I lack much knowledge of IPv6 so I hope for your understandings.

Suppose my EC2 instance's public IP address is 11.22.33.44.

I think I shouldn't set the variable m_broker_addr to the public IP address.

In this case, what configuration is needed to set the broker's address?

/+++++++++++++++++++++++++++++++++++++++++++++++++/

Edited 2016.07.14

The host name (IP address of Amazon EC2) starts with 52.

My PCA10040's address is 00:8D:55:3F:20:A2.

In the picture, A) is shown due to Eclipse Paho's MQTT Publisher example.

This example doesn't use user name nor password. It also uses 1883 port.

I executed the Eclipse Paho's MQTT Publisher example and those packets were captured. With this example, I published data sucessfully.

After that, B) I terminated Eclipse Paho's MQTT Publisher example and executed the Linux commands to connect PCA10040 with RPi3.

I pressed Button 1 from PCA10040.

However, no packets were captured like situation A.

#define APP_MQTT_BROKER_PORT                1883

 case BSP_BUTTON_0:
        {
            if (m_connection_state == false)
            {
                mqtt_client_init(&m_app_mqtt_client);

                memcpy(m_app_mqtt_client.broker_addr.u8, m_broker_addr.u8, IPV6_ADDR_SIZE);
                m_app_mqtt_client.broker_port          = APP_MQTT_BROKER_PORT;
                m_app_mqtt_client.evt_cb               = app_mqtt_evt_handler;
                m_app_mqtt_client.client_id.p_utf_str  = (uint8_t *)m_client_id;
                m_app_mqtt_client.client_id.utf_strlen = strlen(m_client_id);
                m_app_mqtt_client.p_password           = NULL;
                m_app_mqtt_client.p_user_name          = NULL;
                m_app_mqtt_client.transport_type       =  MQTT_TRANSPORT_NON_SECURE /*MQTT_TRANSPORT_SECURE*/ ;
                m_app_mqtt_client.p_security_settings  = NULL /*&m_tls_keys*/ ;

                uint32_t err_code = mqtt_connect(&m_app_mqtt_client);
                // err_code was 0, but the LED 2 didn't turned on.

The err_code value was 0 when I pressed Button 1.

Edited 2016.07.15

This is strange. As you suggested, I sniffed the BT0 interface in Wireshark.

You can download the captured packets to see them in detail; sniff.pcapng.

The red line (packet No. 7 and 11) was created when I pressed Button 1 from PCA10040.

I followed the instruction to configure the non secure port as you mentioned in the comments.

That corresponds to the code part which I posted above.

By the way, this is the result when I checked what command is actually running.

Added 2016.08.10

Received payload.

-Best Regards, Mango

[Stian Røed Hafskjold]

The IoT SDK only supports ipv6, and the m_broker_addr variable should contain the ipv6 address of the MQTT broker. If your cloud service don't support ipv6, you need to translate the ipv6 packets into ipv4 somehow. You can try 6tunnel: http://toxygen.net/6tunnel/

sudo apt-get install 6tunnel

And forward packets from port 1883 (8883 if you are using secure connection)

6tunnel -6 1883 cloud_hostname 1883

And just leave the m_broker_addr as it is.

EDIT:

hex file modified to use non secure connection: nrf52832_xxaa_s1xx_iot.hex

[MANGO]

1. Do I have to install 6tunnel in RPi3 Jessie or my cloud service (Amazon EC2)?

In my case, my EC2 instance is using Ubuntu v14.

Suppose the "cloud_hostname" (in Amazon, it is called as public IP) is 11.22.33.44

and I use port 1883.

So I should type

# 6tunnel -6 1883 11.22.33.44 1883

in my RPi3 after installing 6tunnel?

2. "And just leave the m_broker_addr as it is." Why is that?

[Stian Røed Hafskjold]

1. It is on your RPi3. You can use the ip address the way you describe. The command is correct.

2. Because no matter what the destination ip address is, the 6tunnel will forward every packet arriving on port 1883 to the ip address you specify in the 6tunnel command.

Remember that the MQTT example uses secure connections and port 8883 as default. You can read here on how to not use secure connections and port 1883 instead. (Or you can use secure connections and 6tunnel with port 8883 instead. But it might require some extra setup on the EC2 side.)

[MANGO]

Well, I posted the result after installing 6tunnel in my edited answer.

What seems to be the problem?

-Best Regards, Mango

[Stian Røed Hafskjold]

After executing 6tunnel you get: bind, address already in use. Try to ps aux | grep 6tunnel to see what command is actually running. If it is not the correct one, kill the process and start it again.

What happens if you sniff the BT0 interface in wireshark? Do you see any activity?