Abstract
The paradigm of fog computing has set new trends and heights in the modern world networking and have overcome the major technical complexities of cloud computing. It is not a replacement of cloud computing technology but it just adds feasible advanced characteristics to existing cloud computing paradigm.fog computing not only provide storage, networking and computing services but also provide a platform for IoT (internet of things). However, the fog computing technology also arise the threat to privacy and security of the data and services. The existing security and privacy mechanisms of the cloud computing cannot be applied to the fog computing directly due to its basic characteristics of large-scale geo-distribution, mobility and heterogeneity. This article provides an overview of the present existing issues and challenges in fog computing.