Design and implementation of a multi-layer privacy-preserving router based on raspberry Pi platform: Integration of the Onion router network with advanced DNS protection mechanisms

This paper presents the design and implementation of a multi-layer privacy-preserving network router built on the Raspberry Pi 5 platform.The proposed system integrates several complementary privacy-enhancing technologies, namely the TOR anonymization network, encrypted DNS protocols (DNSCrypt, DNS over HTTPS, DNS over TLS, and Oblivious DNS over HTTPS), a local recursive DNS resolver (Unbound), and DNS-level filtering via Pi-hole.A total of nine distinct operational modes were developed, each offering a different trade-off between the level of privacy protection and network performance -ranging from basic advertisement filtering to full traffic anonymization combined with multi-layer DNS encryption.A physical control interface featuring an OLED display and push buttons was implemented, enabling mode switching without remote shell access.Performance evaluation using the DNS Performance Testing Tool (dnsperf) demonstrated that even the most advanced configurations maintain acceptable response latencies and high query resolution rates.The proposed solution addresses the gap between expensive, closed-source commercial devices and complex open-source systems that require advanced technical expertise, offering an accessible and cost-effective privacy protection tool for individual users and high-risk groups.The total hardware cost does not exceed 200 USD, representing a fraction of the price of commercial solutions with comparable functionality.