Pi‑hole

Pi‑hole is a lightweight, network‑wide DNS sinkhole written primarily in Bash and Go, with a minimal web interface powered by PHP. It intercepts all DNS queries on the host, filters them against a set of blocklists, and returns either an IP from the whitelist or a null response that effectively blocks the domain. The core filtering engine, FTL (Fast Telemetry Library), is a Go binary that runs as a daemon and handles query resolution, caching, and statistics aggregation. Pi‑hole’s architecture is intentionally simple: a single process per host that exposes a RESTful API and a Web UI over HTTPS, allowing developers to integrate it into existing network stacks without needing to manage complex services.

Technical Stack

• Languages: Bash (installer & CLI), Go (FTL daemon), PHP (web UI)
• Database: SQLite for storing configuration, blocklists, and query logs; optional integration with MySQL/PostgreSQL via the API for larger deployments
• Networking: Uses dnsmasq under the hood to serve DNS and DHCP; listens on UDP/TCP ports 53
• Containerization: Official Docker images are available; the image bundles all dependencies, exposes ports 53/80/443, and supports environment variables for configuration
• Operating System Support: Any Linux distribution with systemd or init scripts; Docker can run on Windows/macOS hosts via a VM

Core Capabilities

Pi‑hole exposes a RESTful API (/admin/api.php) that lets developers query statistics, add or remove domains from blocklists, and toggle features programmatically. The API supports JSON and CSV responses, making it easy to integrate with monitoring tools or custom dashboards. Additionally, Pi‑hole can act as a DHCP server, assigning IPs and setting itself as the DNS provider for all clients, which is useful in environments where router configuration is limited. The filtering engine supports IPv4 and IPv6 queries, and the caching layer reduces latency for repeated lookups.

Deployment & Infrastructure

Self‑hosting Pi‑hole is straightforward: install the OS, run the automated installer (or clone the repo for manual control), and configure your network to point DNS traffic at the Pi‑hole host. For scalability, a single Pi‑hole instance can handle hundreds of millions of queries per day on server‑grade hardware, thanks to Go’s efficient concurrency model. In high‑availability scenarios, multiple Pi‑holes can be run in a failover configuration using dnsmasq’s round‑robin or by deploying a load balancer that forwards DNS traffic to the healthiest instance. Containerized deployments simplify CI/CD pipelines, enabling developers to spin up test environments in minutes.

Integration & Extensibility

The plugin ecosystem is modest but growing: developers can write custom resolvers or blocklist generators that plug into FTL via the API. Webhooks can be triggered on query events, allowing integration with external alerting systems (e.g., Slack or PagerDuty). The open‑source nature means any change to the blocklist logic can be forked and merged back, giving teams full control over privacy policies. Additionally, Pi‑hole’s configuration files (/etc/pihole) are plain text, so they can be version‑controlled and managed with infrastructure-as-code tools like Ansible or Terraform.

Developer Experience

Documentation is comprehensive, covering installation, API usage, and advanced tuning. The community forum and Discord channel provide rapid support, while the GitHub issue tracker is actively maintained. For developers who need fine‑grained control, the CLI (pihole) offers commands for status checks, log rotation, and service restarts. The web UI is responsive and built with Bootstrap, making it accessible on mobile devices—a bonus for developers who need to monitor networks on the go.

Use Cases

• Enterprise Networks: Deploy a single Pi‑hole per subnet to block ads, trackers, and malicious domains without installing client software on every device.
• IoT‑Heavy Homes: Prevent smart TVs and mobile apps from reaching ad servers, reducing data usage and improving privacy.
• VPN Gateways: Pair Pi‑hole with OpenVPN or WireGuard to provide ad blocking across mobile connections.
• Testing Environments: Use Dockerized Pi‑hole in CI pipelines to simulate network conditions or validate DNS‑based security controls.

Advantages

Pi‑hole offers performance (Go‑based FTL with caching), flexibility (Docker, CLI, API, DHCP support), and a free, open‑source license that eliminates vendor lock‑in. Its lightweight footprint (under 200 MB) and minimal hardware requirements make it ideal for Raspberry Pi, NAS devices, or virtual machines. Compared to browser‑based blockers, Pi‑hole provides network‑level protection that reaches every device regardless of OS or browser choice, giving developers a single point of control over DNS traffic.