© 2019 Elsevier Inc. The ubiquitous use of Internet-of-Things (IoT) is enabling a new era of wireless Sensor Nodes (SNs) that can be subject to attacks like any other piece of hardware and software. Unfortunately, an open and challenging issue is to what extent legitimate SNs can be trusted. This paper presents an energy-efficient, software-defined-network-based Mobile Code-driven Trust Mechanism (MCTM) for addressing this issue by assessing trust of SNs based on their forwarding behaviors. MCTM uses mobile code to visit the SNs based on pre-defined itineraries while collecting necessary details about these SNs in preparation for assessing their trust. The results gained from the experiments demonstrate a superior performance over a state-of-art technique that is energy-efficient management based on Software-Defined Network (SDN) for SNs. Message overhead is reduced by approximately 50%, which results in consuming less energy when detecting malicious SNs.