  With over 20 million units sold since 2015, Amazon Echo, the Alexa-enabled
smart speaker developed by Amazon, is probably one of the most widely deployed
Internet of Things consumer devices. Despite the very large installed base,
surprisingly little is known about the device's network behavior. We modify a
first generation Echo device, decrypt its communication with Amazon cloud, and
analyze the device pairing, Alexa Voice Service, and drop-in calling protocols.
We also describe our methodology and the experimental setup. We find a minor
shortcoming in the device pairing protocol and learn that drop-in calls are
end-to-end encrypted and based on modern open standards. Overall, we find the
Echo to be a well-designed device from the network communication perspective.
