A high-performance, recursive DNS resolver server with DNSSEC support, focused on preserving privacy.

Use the go get command to install sdns:

go get github.com/semihalev/sdns

You can download the latest release from the Github Repo.

• Docker Package (updated every release)
• Docker Hub (alternative)

$ docker run -d --name sdns -p 53:53 -p 53:53/udp sdns

Install docker-compose and run from the root directory:

$ sudo apt install docker-compose
$ docker-compose up -d

Install and run as a service:

$ brew install sdns
$ brew install semihalev/tap/sdns (updated every release)
$ brew services start sdns

$ snap install sdns

$ yay -S sdns-git

Note: Pre-built binaries, Docker packages, brew taps, and snaps are automatically created by Github workflows.

$ go build

$ make test

To debug your environment, execute the following command:

$ export SDNS_DEBUGNS=true && export SDNS_PPROF=true && ./sdns

The SDNS_DEBUGNS environment variable is beneficial for verifying the RTT (Round Trip Time) of authoritative servers. To use it, send an HINFO query for zones with chaos class.

Here's an example of the output you might receive:

$ dig chaos hinfo example.com

; <<>> DiG 9.17.1 <<>> chaos hinfo example.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29636
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: f27dbb995df5ac79e4fa37c07d131b5bd03aa1c5f802047a7c02fb228a886cb281ecc319323dea81 (good)
;; QUESTION SECTION:
;example.com.			CH	HINFO

;; AUTHORITY SECTION:
example.com.		0	CH	HINFO	"Host" "IPv4:199.43.135.53:53 rtt:142ms health:[GOOD]"
example.com.		0	CH	HINFO	"Host" "IPv4:199.43.133.53:53 rtt:145ms health:[GOOD]"
example.com.		0	CH	HINFO	"Host" "IPv6:[2001:500:8f::53]:53 rtt:147ms health:[GOOD]"
example.com.		0	CH	HINFO	"Host" "IPv6:[2001:500:8d::53]:53 rtt:148ms health:[GOOD]"

In sdns, you have the ability to add custom plugins. The sequence of the plugins and the middlewares has a mutual impact on their execution. Config keys must be strings, and values can be of any type. Plugins are loaded before the cache middleware in the specified order.

The plugin interface is straightforward. For additional information, please refer to the example plugin.

[plugins]
     [plugins.example]
     path = "/path/to/exampleplugin.so"
     config = {key_1 = "value_1", intkey = 2, boolkey = true, keyN = "nnn"}
     [plugins.another]
     path = "/path/to/anotherplugin.so"

• Increase the file descriptor limit on your server

• Linux/BSD/Darwin/Windows supported
• DNS RFC compatibility
• DNS lookups within listed ipv4 and ipv6 auth servers
• DNS caching with prefetch support
• DNSSEC validation
• DNS over TLS support (DoT)
• DNS over HTTPS support (DoH) with HTTP/3 support
• DNS over QUIC support (DoQ)
• Outbound IP selection
• Middleware Support, you can add, your own middleware
• RTT priority within listed servers
• Failover forwarders while returning failured responses
• Forwarder support
• EDNS Cookie Support (client<->server)
• EDNS NSID Support
• Full IPv6 support (client<->server, server<->server)
• Query based ratelimit
• IP based ratelimit
• Access list
• Access log
• Prometheus basic query metrics
• Black-hole for malware responses
• HTTP API support
• Cache Purge API and query support
• Answer chaos txt queries for version.bind and hostname.bind
• Empty zones support described at RFC 1918
• External plugins supported

• More tests
• Try lookup NS address better way
• DNS over TLS support
• DNS over HTTPS support
• Full DNSSEC support
• RTT optimization
• Access list
• Periodic priming queries described at RFC 8109
• Full IPv6 support (server<->server communication)
• Query name minimization to improve privacy described at RFC 7816
• DNAME Redirection in the DNS described at RFC 6672
• Automated Updates DNSSEC Trust Anchors described at RFC 5011
• DNS64 DNS Extensions for NAT from IPv6 Clients to IPv4 Servers described at RFC 6147
• DNS over QUIC support described at RFC 9250

• Server Specifications:
  • Processor: Intel Xeon E5-2609 v4 CPU
  • Memory: 32GB

• Tool Name: DNS-OARC dnsperf
• Benchmark Configuration:
  • Query Data Volume: 50,000 sample queries

Benchmarks were performed on the following DNS resolvers: sdns-1.3.3, pdns-recursor-4.8.4, bind-9.19.12, unbound-1.17.1.

We welcome pull requests. If you're considering significant changes, please start a discussion by opening an issue first.

Before submitting patches, please review our CONTRIBUTING guidelines.

• miekg/dns - Alternative (more granular) approach to a DNS library

• coredns/coredns
• looterz/grimd

MIT