SDNS – recursive DNS resolver with DNSSEC validation

SDNS is a recursive DNS resolver. It performs iterative resolution starting from the DNS root rather than requiring another recursive resolver to provide answers on its behalf.

The software is designed for operators who want to run their own resolver while retaining modern DNS security, privacy and policy capabilities. It combines standards-based recursive resolution with encrypted client transports and a configurable policy layer.

SDNS also places considerable emphasis on operational visibility. Administrators can inspect resolver behaviour through metrics, an HTTP API and dnstap while applying controls that limit the amount of recursive work attributable to an individual request.

This is free and open source software.

Key Features

• Performs recursive resolution from the DNS root.
• Validates responses against DNSSEC trust anchors.
• Supports QNAME minimisation and aggressive use of authenticated denial-of-existence records.
• Provides DNS-over-TLS, DNS-over-HTTPS with HTTP/3 and DNS-over-QUIC.
• Can serve stale cached answers when normal resolution fails.
• Supports Response Policy Zones with multiple trigger types.
• Provides blocklists, per-client views, access lists and rate limiting.
• Detects potential DNS reflection attacks.
• Supports conditional forwarding and whole-server forwarder operation.
• Provides DNS64 synthesis and optional EDNS Client Subnet support.
• Can provide DNS services for Kubernetes clusters.
• Exports Prometheus metrics and dnstap data and provides an HTTP API.
• Includes a recursion firewall that limits the work generated by individual requests.

Website: github.com/semihalev/sdns
Support:
Developer: Semih Halev
License: MIT License

SDNS is written in Go. Learn Go with our recommended free books and free tutorials.

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