Recent advances in Internet of Things (IoT) connectivity have made IoT devices prone to Cyber attacks. Moreover, vendors are eager to provide autonomous and open source device, which in turn adds more security threat to the system. In this paper, we consider network traffic attack, and provide a Fog-assisted solution, dubbed as FIRE- WORK, that reduces risk of security attacks by periodically monitor- ing network traffic, and applying traffic isolation techniques to overcome network congestion and performance degradation.