NetBird is a configuration-free peer-to-peer VPN and centralized access control system built on WireGuard. It consists of a cross-platform client daemon (Linux, Windows, macOS, Android, iOS, FreeBSD, WebAssembly), a management server, a signal server for NAT traversal coordination, a relay server for fallback connectivity, and a reverse proxy with an LLM gateway layer. The client daemon manages WireGuard interfaces, DNS, firewall rules, and peer connections via ICE/STUN/TURN, while the management server provides REST/gRPC APIs for account management, network map computation, posture checks, and policy enforcement. The proxy component adds middleware for authentication, LLM request parsing, cost metering, and guardrails, enabling identity-aware access to private resources and AI APIs over the encrypted tunnel. Architecturally, the system is a distributed set of microservices: the client runs as a background daemon with a CLI and a desktop GUI (Wails v3 + React), communicating with the management server via gRPC and REST. Relay and signal servers facilitate NAT traversal, and the proxy can be deployed as a standalone reverse proxy. The management server supports multiple database backends (PostgreSQL, SQLite, MySQL) and caching via Redis. Telemetry and metrics are exported to Prometheus or InfluxDB. The codebase is heavily platform-adapted with build-tagged files, and includes extensive unit, integration, and end-to-end tests. Key entry points include client/main.go (CLI), client/ui/main.go (desktop GUI), management/main.go (management server), relay/main.go (relay server), signal/main.go (signal server), proxy/cmd/proxy/main.go (proxy), and combined/main.go (all-in-one server). Data flows involve client authentication, network map retrieval, WireGuard tunnel setup, peer-to-peer connection establishment via ICE/relay, and optional proxy middleware processing for HTTP/LLM traffic. External dependencies include WireGuard, PostgreSQL/SQLite/MySQL, Redis, MaxMind GeoLite2, pyroscope, gRPC, protobuf, Wails, and various system tools (iptables, nftables, resolvconf).
Firezone is a zero-trust network access platform providing secure remote access through VPN-like tunnels. The production system consists of a cloud-based management portal (Elixir/Phoenix), data-plane components (Rust gateways and relays), and native clients for macOS/iOS, Android, Windows, and Linux. The portal manages multi-tenant accounts, identity (OIDC, SAML, email OTP, X.509), access policies, device posture, and logs. It exposes a REST API (PortalAPI) for CRUD operations and WebSocket channels for real-time client/gateway connectivity. The Rust core (connlib) handles ICE/STUN/TURN connectivity, WireGuard tunnels, and eBPF-accelerated packet routing. PostgreSQL is used for persistence with logical replication for change data capture, Oban for background job processing, and Redis for caching/presence. External dependencies include identity providers (Entra, Okta, Google Workspace), device management systems (Intune, Defender, SentinelOne, etc.), log sinks (Splunk, Datadog, Elastic, S3), and billing (Stripe). The architecture separates the web admin interface (PortalWeb), REST API (PortalAPI), and internal ops (PortalOps) into distinct endpoints. Data-plane components (gateway, relay) communicate via WebSockets with the API to receive policy updates. Clients connect to relays using ICE/STUN/TURN. The system uses Phoenix PubSub for real-time updates and Postgres logical replication to propagate changes to connected clients and gateways. Key entry points: PortalWeb.Endpoint (admin UI), PortalAPI.Endpoint (REST/WebSocket for clients and gateways), PortalOps.Endpoint (ops dashboard). Rust binaries: firezone-gateway, firezone-relay, firezone-headless-client, firezone-gui-client. Mobile apps: Firezone iOS/macOS (Swift), Firezone Android (Kotlin).
MicroLink v2 is a production-ready Tailscale VPN client for ESP32-S3 devices that establishes secure WireGuard tunnels through Tailscale's control plane. It implements the full Tailscale protocol stack including Noise protocol for control plane encryption, HTTP/2 framing, DISCO peer discovery, STUN for NAT traversal, DERP relay fallback, and WireGuard encryption via wireguard-lwip integration. The architecture uses a multi-task FreeRTOS design with separate tasks for coordination, WireGuard management, DERP transmission, network I/O, and application logic, communicating via message queues and event groups. Key features include WiFi/cellular network failover with health monitoring, zero-copy WireGuard receive option for high-throughput scenarios, NVS-based peer caching with LRU eviction, and an HTTP configuration server for runtime management. The code demonstrates strong protocol fidelity through direct reference to Tailscale's Go source files while adapting to embedded constraints.