Sensor nodes are small, autonomous, battery-powered devices that use a wireless network interface to communicate with other sensor nodes. Together these sensor nodes form a Wireless Sensor Network (WSN), which has the purpose to sense information about the environment. Before a WSN is deployed, it is tested using simulators and testbeds. Both simulators and testbeds are not able to fully capture all non-deterministic behaviour of the environment in which the WSNs are deployed. Passive inspection is an approach that detects problems within a WSN during deployment. Passive inspection makes use of the broadcast nature of wireless communication and is realised by overhearing messages sent by sensor nodes. The limitation of passive inspection is that operator of the WSN has to wait until a sensor node transmits a message and that this message contains the specific information is needed. To overcome this limitation active inspection can be used, and is realised by injecting messages into the deployment to force a reaction from a sensor node. The concept of passive inspection is not new and has already been evaluated in a simulator and presented in a demo. In this thesis we will further evaluate the practical use of passive inspection using real hardware and we will try to extend passive inspection with active inspection. In order to evaluate passive and active inspection, we designed and implemented an inspection network and an analysis tool. The evaluation compared the normal operation of a deployment with an operation containing a previously resolved bug. The result of this evaluation is that the analysis tool is clearly capable of detecting the previously resolved bug. In this way we showed that passive inspection would have been able to detect that problem when it occurred in a real-life deployment. The evaluation of active inspection showed that active inspection can be used without negatively effecting the behaviour of the sensor nodes in the deployment.