Ensure that the attribute 'ip_filter_permissive_rule' in Defender for IoT is not set to false

Not having IP filtering configured could make IoT Hub more prone to attacks.

In Azure Console -

1. Go to Azure IoT Hub.
2. Choose an IoT Hub to edit.
3. In the Defender for IoT, Choose Settings.
4. Click on the Recommendation Configuration and choose the IP Filter Permissive rule recommendation.
5. Click Enable.

In Terraform -

1. In the azurerm_iot_security_solution resource, set recommendations_enabled.ip_filter_permissive_rule to true.

References:
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/iot_security_solution#ip_filter_permissive_rule