We expose concretely the information leakage occurring in an IEEE 802.15.4-based ZigBee meshed network. We deploy an IoT platform and used a killerbee sniffer to eavesdrop the communication between the motes. Metadata and control traffic are exploited in depth to recover protocol instances, routes, identity, capability and activity of the devices. We experiment different levels of security for the communications from none to the best available. Even when security is enforced, information leakages are not avoided. We propose simple countermeasures to prevent an outsider from monitoring a ZigBee network.