dnsproxy

README

DNS Proxy

A simple DNS proxy server that supports all existing DNS protocols including DNS-over-TLS, DNS-over-HTTPS, and DNSCrypt.

Moreover, it can work as a DNS-over-HTTPS and/or DNS-over-TLS server.

• How to build
• Usage
• Examples
  • Simple options
  • Encrypted upstreams
  • Encrypted DNS server
  • Additional features
  • Fastest addr + cache-min-ttl
  • Specifying upstreams for domains
  • EDNS Client Subnet
  • Bogus NXDomain

How to build

You will need go v1.14 or later.

$ go build

Usage

Usage:
  dnsproxy [OPTIONS]

Application Options:
  -v, --verbose         Verbose output (optional)
  -o, --output=         Path to the log file. If not set, write to stdout.
  -l, --listen=         Listen address (default: 0.0.0.0)
  -p, --port=           Listen port. Zero value disables TCP and UDP listeners (default: 53)
  -h, --https-port=     Listen port for DNS-over-HTTPS (default: 0)
  -t, --tls-port=       Listen port for DNS-over-TLS (default: 0)
  -c, --tls-crt=        Path to a file with the certificate chain
  -k, --tls-key=        Path to a file with the private key
  -u, --upstream=       An upstream to be used (can be specified multiple times)
  -b, --bootstrap=      Bootstrap DNS for DoH and DoT, can be specified multiple times (default: 8.8.8.8:53)
  -f, --fallback=       Fallback resolvers to use when regular ones are unavailable, can be specified multiple times
      --all-servers     If specified, parallel queries to all configured upstream servers are enabled
      --fastest-addr    Respond to A or AAAA requests only with the fastest IP address
      --cache           If specified, DNS cache is enabled
      --cache-size=     Cache size (in bytes). Default: 64k
      --cache-min-ttl=  Minimum TTL value for DNS entries, in seconds. Capped at 3600. Artificially extending TTLs should only be done with
                        careful consideration.
      --cache-max-ttl=  Maximum TTL value for DNS entries, in seconds.
  -r, --ratelimit=      Ratelimit (requests per second) (default: 0)
      --refuse-any      If specified, refuse ANY requests
      --edns            Use EDNS Client Subnet extension
      --edns-addr=      Send EDNS Client Address
      --ipv6-disabled   If specified, all AAAA requests will be replied with NoError RCode and empty answer
      --bogus-nxdomain= Transform responses that contain only given IP addresses into NXDOMAIN. Can be specified multiple times.
      --version         Prints the program version

Help Options:
  -h, --help            Show this help message

Examples

Simple options

Runs a DNS proxy on 0.0.0.0:53 with a single upstream - Google DNS.

./dnsproxy -u 8.8.8.8:53

The same proxy with verbose logging enabled writing it to the file log.txt.

./dnsproxy -u 8.8.8.8:53 -v -o log.txt

Runs a DNS proxy on 127.0.0.1:5353 with multiple upstreams.

./dnsproxy -l 127.0.0.1 -p 5353 -u 8.8.8.8:53 -u 1.1.1.1:53

Encrypted upstreams

DNS-over-TLS upstream:

./dnsproxy -u tls://dns.adguard.com

DNS-over-HTTPS upstream with specified bootstrap DNS:

./dnsproxy -u https://dns.adguard.com/dns-query -b 1.1.1.1:53

DNSCrypt upstream (DNS Stamp of AdGuard DNS):

./dnsproxy -u sdns://AQIAAAAAAAAAFDE3Ni4xMDMuMTMwLjEzMDo1NDQzINErR_JS3PLCu_iZEIbq95zkSV2LFsigxDIuUso_OQhzIjIuZG5zY3J5cHQuZGVmYXVsdC5uczEuYWRndWFyZC5jb20

DNS-over-HTTPS upstream (DNS Stamp of Cloudflare DNS):

./dnsproxy -u sdns://AgcAAAAAAAAABzEuMC4wLjGgENk8mGSlIfMGXMOlIlCcKvq7AVgcrZxtjon911-ep0cg63Ul-I8NlFj4GplQGb_TTLiczclX57DvMV8Q-JdjgRgSZG5zLmNsb3VkZmxhcmUuY29tCi9kbnMtcXVlcnk

DNS-over-TLS upstream with two fallback servers (to be used when the main upstream is not available):

./dnsproxy -u tls://dns.adguard.com -f 8.8.8.8:53 -f 1.1.1.1:53

Encrypted DNS server

Runs a DNS-over-TLS proxy on 127.0.0.1:853.

./dnsproxy -l 127.0.0.1 --tls-port=853 --tls-crt=example.crt --tls-key=example.key -u 8.8.8.8:53 -p 0 

Runs a DNS-over-HTTPS proxy on 127.0.0.1:443.

./dnsproxy -l 127.0.0.1 --https-port=443 --tls-crt=example.crt --tls-key=example.key -u 8.8.8.8:53 -p 0 

Additional features

Runs a DNS proxy on 0.0.0.0:53 with rate limit set to 10 rps, enabled DNS cache, and that refuses type=ANY requests.

./dnsproxy -u 8.8.8.8:53 -r 10 --cache --refuse-any

Runs a DNS proxy on 127.0.0.1:5353 with multiple upstreams and enable parallel queries to all configured upstream servers

./dnsproxy -l 127.0.0.1 -p 5353 -u 8.8.8.8:53 -u 1.1.1.1:53 -u tls://dns.adguard.com --all-servers

Fastest addr + cache-min-ttl

This option would be useful to the users with problematic network connection. In this mode, dnsproxy would detect the fastest IP address among all that were returned, and it will return only it.

Additionally, for those with problematic network connection, it makes sense to override cache-min-ttl. In this case, dnsproxy will make sure that DNS responses are cached for at least the specified amount of time.

It makes sense to run it with multiple upstream servers only.

Run a DNS proxy with two upstreams, min-TTL set to 10 minutes, fastest address detection is enabled:

./dnsproxy -u 8.8.8.8 -u 1.1.1.1 --cache --cache-min-ttl=600 --fastest-addr

who run dnsproxy with multiple upstreams

Specifying upstreams for domains

You can specify upstreams that will be used for a specific domain(s). We use the dnsmasq-like syntax (see --server description here).

Syntax: [/[domain1][/../domainN]/]upstreamString

If one or more domains are specified, that upstream (upstreamString) is used only for those domains. Usually, it is used for private nameservers. For instance, if you have a nameserver on your network which deals with xxx.internal.local at 192.168.0.1 then you can specify [/internal.local/]192.168.0.1, and dnsproxy will send all queries to that nameserver. Everything else will be sent to the default upstreams (which are mandatory!).

1. An empty domain specification, // has the special meaning of "unqualified names only" ie names without any dots in them.
2. More specific domains take precedence over less specific domains, so: --upstream=[/host.com/]1.2.3.4 --upstream=[/www.host.com/]2.3.4.5 will send queries for *.host.com to 1.2.3.4, except *.www.host.com, which will go to 2.3.4.5
3. The special server address '#' means, "use the standard servers", so: --upstream=[/host.com/]1.2.3.4 --upstream=[/www.host.com/]# will send queries for *.host.com to 1.2.3.4, except *.www.host.com which will be forwarded as usual.

Examples

Sends queries for *.local domains to 192.168.0.1:53. Other queries are sent to 8.8.8.8:53.

./dnsproxy -u 8.8.8.8:53 -u [/local/]192.168.0.1:53

Sends queries for *.host.com to 1.1.1.1:53 except for *.maps.host.com which are sent to 8.8.8.8:53 (as long as other queries).

./dnsproxy -u 8.8.8.8:53 -u [/host.com/]1.1.1.1:53 -u [/maps.host.com/]#`

EDNS Client Subnet

To enable support for EDNS Client Subnet extension you should run dnsproxy with --edns flag:

./dnsproxy -u 8.8.8.8:53 --edns

Now if you connect to the proxy from the Internet - it will pass through your original IP address's prefix to the upstream server. This way the upstream server may respond with IP addresses of the servers that are located near you to minimize latency.

If you want to use EDNS CS feature when you're connecting to the proxy from a local network, you need to set --edns-addr=PUBLIC_IP argument:

./dnsproxy -u 8.8.8.8:53 --edns --edns-addr=72.72.72.72

Now even if your IP address is 192.168.0.1 and it's not a public IP, the proxy will pass through 72.72.72.72 to the upstream server.

Bogus NXDomain

This option is similar to dnsmasq bogus-nxdomain. If specified, dnsproxy transforms responses that contain only the given IP addresses into NXDOMAIN. Can be specified multiple times.

In the example below, we use AdGuard DNS server that returns 0.0.0.0 for blocked domains, and tranform them to NXDOMAIN.

./dnsproxy -u 176.103.130.130:53 --bogus-nxdomain=0.0.0.0