command module
Version: v0.3.1 Latest Latest

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Published: Apr 23, 2020 License: MIT Imports: 30 Imported by: 0



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💫 Lightweight, fast recursive dns server with dnssec support

Based on kenshinx/godns, looterz/grimd


go get



or run with Docker image

docker run -d --name sdns -p 53:53 -p 53:53/udp -p 853:853 -p 8053:8053 -p 8080:8080 sdns
  • Port 53 DNS server
  • Port 853 DNS-over-TLS server
  • Port 8053 DNS-over-HTTPS server
  • Port 8080 HTTP API


$ go build


$ make test


Flag Desc
config Location of the config file, if not found it will be generated

Debug Environment

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

DEBUGNS enviroment useful when you check authoritive servers RTT times. Usage: send HINFO query for zones.

Example Output:

$ dig hinfo .

; <<>> DiG 9.10.6 <<>> hinfo .
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23338
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 1

; EDNS: version: 0, flags:; udp: 1536
;.				IN	HINFO

.			20	IN	HINFO	"ns" "host: rtt:13ms"
.			20	IN	HINFO	"ns" "host: rtt:14ms"
.			20	IN	HINFO	"ns" "host: rtt:14ms"
.			20	IN	HINFO	"ns" "host: rtt:16ms"
.			20	IN	HINFO	"ns" "host: rtt:16ms"
.			20	IN	HINFO	"ns" "host: rtt:36ms"
.			20	IN	HINFO	"ns" "host: rtt:47ms"
.			20	IN	HINFO	"ns" "host: rtt:54ms"
.			20	IN	HINFO	"ns" "host: rtt:54ms"
.			20	IN	HINFO	"ns" "host: rtt:59ms"
.			20	IN	HINFO	"ns" "host: rtt:61ms"
.			20	IN	HINFO	"ns" "host: rtt:71ms"
.			20	IN	HINFO	"ns" "host: rtt:104ms"

Configuration (v0.3.1)

Key Desc
version Config version
blocklists List of remote blocklists
blocklistdir List of locations to recursively read blocklists from (warning, every file found is assumed to be a hosts-file or domain list)
loglevel What kind of information should be logged, Log verbosity level crit,error,warn,info,debug
accesslog The location of access log file, leave blank for disable. SDNS uses Common Log Format by default.
bind Address to bind to for the DNS server. Default :53
bindtls Address to bind to for the DNS-over-TLS server. Default :853
binddoh Address to bind to for the DNS-over-HTTPS server. Default :8053
tlscertificate TLS certificate file path
tlsprivatekey TLS private key file path
outboundips Outbound ip addresses, if you set multiple, sdns can use random outbound ip address
rootservers DNS Root servers
root6servers DNS Root IPv6 servers
rootkeys DNS Root keys for dnssec
fallbackservers Fallback servers IP addresses
api Address to bind to for the http API server, leave blank for disable
nullroute IPv4 address to forward blocked queries to
nullroutev6 IPv6 address to forward blocked queries to
accesslist Which clients allowed to make queries
timeout Query timeout for dns lookups in duration Default: 5s
connecttimeout Connect timeout for dns lookups in duration Default: 2s
hostsfile Enables serving zone data from a hosts file, leave blank for disable
expire Default cache TTL in seconds Default: 600
cachesize Cache size (total records in cache) Default: 256000
maxdepth Maximum recursion depth for nameservers. Default: 30
ratelimit Query based ratelimit per second, 0 for disable. Default: 0
clientratelimit Client ip address based ratelimit per minute, 0 for disable. if client support edns cookie no limit. Default: 0
blocklist Manual blocklist entries
whitelist Manual whitelist entries

Server Configuration Checklist

  • Increase file descriptor on your server


  • Linux/BSD/Darwin/Windows supported
  • DNS RFC compatibility
  • DNS lookups within listed servers
  • DNS caching
  • DNSSEC validation
  • DNS over TLS support
  • DNS over HTTPS support
  • Middleware Support
  • RTT priority within listed servers
  • EDNS Cookie Support (client<->server)
  • Basic IPv6 support (client<->server)
  • Query based ratelimit
  • IP based ratelimit
  • Access list
  • Prometheus basic query metrics
  • Black-hole internet advertisements and malware servers
  • HTTP API support
  • Outbound IP selection


  • 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
  • Automated Updates DNSSEC Trust Anchors described at RFC 5011
  • Full IPv6 support (server<->server communication)
  • Query name minimization to improve privacy described at RFC 7816


Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

Made With

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





A Lightweight fast recursive dns server with dnssec support. for more information.

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