Pi-hole and ntopng monitor mesh networks via an inline L2 bridge

This review examines a self-hosted solution for gaining per-device network visibility on consumer mesh routers, leveraging Pi-hole, ntopng, and a Raspberry Pi as a transparent Layer 2 bridge.

The Answer Up Front

For self-hosters and network enthusiasts frustrated by the lack of monitoring capabilities in consumer mesh networks like Eero, this inline Layer 2 bridge setup with Pi-hole and ntopng offers a robust, low-latency solution. It provides granular per-device, per-protocol, and per-flow visibility without requiring cooperation from the mesh router itself. Skip this if you lack the hardware skills for a Raspberry Pi build or if your network monitoring needs are satisfied by basic router logs. This approach delivers deep network insights using widely available open-source tools and custom hardware.

Methodology

This v0 review draws on the founder's published claims at the Reddit post by aigor_riera and the detailed blog post at cerberuslabs.tech/blog/home-network-monitoring-stack. Independent benchmarks are pending. Update cadence: re-tested when claims diverge from observed behavior.

• Tool Name + Version + Date Observed: Pi-hole (latest stable as of 2026-05-28), ntopng Community Edition (latest stable as of 2026-05-28), Raspberry Pi (unspecified model, likely a 3B+ or 4 for gigabit NICs).
• Source Signal URL: https://www.reddit.com/r/selfhosted/comments/1tqeh47/monitoring_a_mesh_network_with_no_mirror_port/
• What's Covered: The technical architecture of the inline L2 bridge, the specific roles of Pi-hole and ntopng, the reported latency impact, and the hardware bypass mechanism. The review covers the founder's claims regarding functionality and performance.
• What's NOT Covered: Independent verification of the claimed latency, long-term stability under various network loads, power consumption metrics, or comparative analysis with commercial network monitoring solutions. Edge cases related to specific mesh router firmware versions or complex network topologies are also not covered.

What It Does

Transparent Layer 2 Bridge

The core of this monitoring solution is a Raspberry Pi configured as a transparent Layer 2 bridge. This setup positions the Pi physically inline between the modem and the mesh router's WAN port. The founder, aigor_riera, describes using two USB 3.0 gigabit NICs in addition to the onboard NIC, all bridged in the kernel. This ensures every WAN packet traverses the Pi, allowing for passive monitoring without the mesh router's explicit support for port mirroring.

DNS and Flow Analysis

Pi-hole is deployed to handle DNS resolution for the entire local area network, routing upstream DNS queries over DoH to Cloudflare. This centralizes DNS requests, enabling ad-blocking and basic domain-level traffic logging. Ntopng, listening on the kernel bridge interface, captures and analyzes network flows. This provides detailed per-device, per-protocol, and per-flow visibility, effectively overcoming the limitations of consumer-grade mesh routers that typically abstract away such granular data.

Resilient Hardware Bypass

A critical design element is a hardware bypass mechanism. The founder notes the importance of building a GPIO-driven relay that, in the event of the Raspberry Pi failing, automatically switches traffic to flow directly from the modem to the Eero router. This ensures internet connectivity for the household remains uninterrupted, addressing a key reliability concern for inline network devices.

Minimal Latency Impact

The founder reports that the added latency from inserting the Raspberry Pi inline is

The investor read

This solution highlights a persistent gap in the consumer networking market: the lack of granular network visibility and control offered by popular mesh router systems. While this specific implementation is a DIY project, it signals a demand for more advanced network diagnostics and security features, even in home environments. An investable opportunity could emerge in pre-built, plug-and-play hardware appliances that offer similar inline monitoring capabilities with a polished user experience, targeting power users or small businesses. Alternatively, a managed service layer built on top of open-source tools like ntopng, offering simplified deployment and analysis for these types of setups, could capture this niche. The reliance on open-source components suggests a low-cost base, making it attractive for bootstrapped ventures focused on specific pain points.