  Wireless Sensor Networks (WSNs) often lack interfaces for remote debugging.
Thus, fault diagnosis and troubleshooting are conducted at the deployment site.
Currently, WSN operators lack dedicated tools that aid them in this process.
Therefore, we introduce EyeSec, a tool for WSN monitoring and maintenance in
the field. An Augmented Reality Device (AR Device) identifies sensor nodes
using optical markers. Portable Sniffer Units capture network traffic and
extract information. With those data, the AR Device network topology and data
flows between sensor nodes are visualized. Unlike previous tools, EyeSec is
fully portable, independent of any given infrastructure and does not require
dedicated and expensive AR hardware. Using passive inspection only, it can be
retrofitted to already deployed WSNs. We implemented a proof of concept on
low-cost embedded hardware and commodity smart phones and demonstrate the usage
of EyeSec within a WSN test bed using the 6LoWPAN transmission protocol.
