AWS IoT applies security to protect our system. To allow a device to send data, we need to attach the following statements to the device—iot:Connect, iot:Subscribe, iot:Publish, and iot:Receive.

We do this by creating a policy in AWS that includes these statements, as follows:

1. From the IoT console at https://console.aws.amazon.com/iot/, we can click on Secure, and then Policies, and register a new policy by clicking on the Create a policy button as shown in the following screenshot:

2. Then, we can provide the iiot-book-policy-4-mqtt name and add the iot:Connect, iot:Subscribe, and iot:Publish or iot:* statements, which is strongly discouraged for security reasons. We need to allow the statement and click on the Create button to build the policy:

Otherwise, we can copy and paste the following code into the Advanced mode tab:

{
 "Version": "2012-10-17",
 "Statement": [
     {
         "Action": [
            "iot:Publish",
            "iot:Subscribe",
            "iot:Connect",
            "iot:Receive"
     ],
         "Effect": "Allow",
         "Resource": [
             "*"
   ]
    }
  ]
}