I have a typical IoT set up where a set of IoT devices running embedded Linux are connected to a cloud IoT server. The underlying carrier connection to the internet is over GSM. All communication to the server is secured with TLS implementation including the mutual authentication with server. The devices generate and store sensitive data, which is also secured with secure local storage (though that is not with TPM, rather software based secured storage).

In this scenario, does it make a good sense to also install an embedded firewall on my device? I mean doesn’t strong encryption and certificate based authentication ensure complete security to IoT device?