Legacy electrical grids are urged to evolve towards smart grids, the smarter power delivery system that relies heavily on ICT. Numerous smart grids applications are expected to be developed for efficient management and utilization of electricity at the demand side such as home automation, Advanced Metering Infrastructure (AMI), dynamic energy pricing, efficient load management, etc. For easing and boosting the development of new demand side services, the concept of Home Energy Gateway (HEG) has recently been proposed in literature. It involves communication with the utility as well as with devices at the consumer sites. The literature still lacks a comprehensive HEG design that could provide all essential features such as zero-configuration, auto-discovery, seamless plug & play communication, interoperability and integration, customers privacy and communication security. This paper addresses the HEG challenges in an effective way through the design of suitable communication frameworks and a security mechanism for enabling strong protection against cyber attacks. The proposed system effectively copes with the interoperability and integration issues between plethora of heterogeneous devices at the consumer sites. The devices in proposed system inherit plug & play features and support zero-configuration and seamless networking. Further, the proposed system design is technology-agnostic and flexible enough to be adopted for the implementation of any specific demand side service. This paper also evaluates the proposed system in real-networking environment and presents performance metrics.