sdns

README

🚀 Privacy important, fast, recursive dns resolver server with dnssec support

Installation

go get github.com/semihalev/sdns

or

download latest release

or run package Docker image or alternative from Docker hub

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

Building

$ go build

Testing

$ make test

Flags

Flag	Desc
config	Location of the config file, if config file not found, a config will generate
v	Show version information

Debug Environment

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

SDNS_DEBUGNS enviroment useful when you want to check authoritive servers RTT times. Usage: send HINFO query for zones with chaos class.

Example Output:

$ 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]"

Configuration (v1.1.0)

Key	Desc
version	Config version
blocklists	List of remote blocklists address list. All lists will be download to blocklist folder.
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, left blank for disabled. 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 ipv4 addresses, if you set multiple, sdns can use random outbound ipv4 address by request based
outboundip6s	Outbound ipv6 addresses, if you set multiple, sdns can use random outbound ipv6 address by request based
rootservers	DNS Root IPv4 servers
root6servers	DNS Root IPv6 servers
rootkeys	Trusted anchors for DNSSEC
fallbackservers	Failover resolver ipv4 or ipv6 addresses with port, left blank for disabled: Example: "8.8.8.8:53"
api	Address to bind to for the http API server, left blank for disabled
nullroute	IPv4 address to forward blocked queries to
nullroutev6	IPv6 address to forward blocked queries to
accesslist	Which clients allowed to make queries
timeout	Network timeout for each dns lookups in duration Default: 2s
hostsfile	Enables serving zone data from a hosts file, left blank for disabled
expire	Default error cache TTL for in seconds Default: 600
cachesize	Cache size (total records in cache) Default: 256000
maxdepth	Maximum iteration depth for a query Default: 30
ratelimit	Query based ratelimit per second, 0 for disabled. 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
cookiesecret	DNS cookie secret (RFC 7873), if no cookiesecret set, it will be generate automatically
nsid	DNS server identifier (RFC 5001), it's useful while operating multiple sdns. left blank for disabled
chaos	Enable to answer version.server, version.bind, hostname.bind and id.server chaos txt queries.
qname_min_level	Qname minimize level.If higher, it can be more complex and impact the response performance. If set 0, qname min will be disable
emptyzones	Empty zones return answer for RFC 1918 zones. Please see http://as112.net/ for details.

Plugins Configuration

You can add your own plugins to sdns. The plugin order is very important. The orders of plugins and middlewares will effect each other. Config keys should be string and values can be anything. The plugins will load before cache middleware with their orders.

Plugin interface is very simple. For more information, you can look the example plugin

Example Config

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

Server Configuration Checklist

• Increase file descriptor on your server

Features

• Linux/BSD/Darwin/Windows supported
• DNS RFC compatibility
• DNS lookups within listed ipv4 and ipv6 auth servers
• DNS caching
• DNSSEC validation
• DNS over TLS support (DoT)
• DNS over HTTPS support (DoH)
• Outbound IP selection
• Middleware Support, you can add, your own middleware
• RTT priority within listed servers
• Failover forwarders while returning failured responses
• 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

TODO

• 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

Performance

These benchmarks were run on a server with Intel Xeon E5-2609 v4 cpu and 32GB memory on localhost. DNS-OARC dnsperf (https://www.dns-oarc.net/tools/dnsperf) tool used with 50.000 sample query data.

Resolver	RESPONSE	NOERROR	SERVFAIL	NXDOMAIN	RUN TIME	QPS
SDNS	%99,88	%73,60	%1,36	%25,04	101s480ms	492/s
PowerDNS	%99,59	%72,76	%1,40	%25,84	123s930ms	402/s
Bind	%99,40	%72,98	%1,09	%25,94	115s150ms	431/s
Unbound	%99,14	%73,19	%0,90	%25,90	178s80ms	278/s

Who Used

CubeDNS public open resolver project using sdns on multi location. The project supported both UDP and TCP also DoT and DoH.

Proto	Servers
IPv4	195.244.44.44, 195.244.44.45
IPv6	2a0a:be80::cbe:4444, 2a0a:be80::cbe:4445
DoH	https://cubedns.com/dns-query

Contributing

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

Inspired by

• coredns/coredns
• looterz/grimd

License

MIT

Documentation

Overview

Privacy important, fast recursive dns resolver server with dnssec support. https://sdns.dev for more information.