dnsproxy

README

DNS Proxy

A simple DNS proxy server that supports all existing DNS protocols including DNS-over-TLS, DNS-over-HTTPS, DNSCrypt, and DNS-over-QUIC. Moreover, it can work as a DNS-over-HTTPS, DNS-over-TLS or DNS-over-QUIC server.

• How to install
• How to build
• Usage
• Examples
  • Simple options
  • Encrypted upstreams
  • Encrypted DNS server
  • Additional features
  • DNS64 server
  • Fastest addr + cache-min-ttl
  • Specifying upstreams for domains
  • EDNS Client Subnet
  • Bogus NXDomain

How to install

There are several options how to install dnsproxy.

1. Grab the binary for your device/OS from the Releases page.
2. Use the official Docker image.
3. Build it yourself (see the instruction below).

How to build

You will need Go v1.21 or later.

$ make build

Usage

Usage:
  dnsproxy [OPTIONS]

Application Options:
      --config-path=               yaml configuration file. Minimal working configuration in config.yaml.dist. Options passed through command
                                   line will override the ones from this file.
  -o, --output=                    Path to the log file. If not set, write to stdout.
  -c, --tls-crt=                   Path to a file with the certificate chain
  -k, --tls-key=                   Path to a file with the private key
      --https-server-name=         Set the Server header for the responses from the HTTPS server. (default: dnsproxy)
      --https-userinfo=            If set, all DoH queries are required to have this basic authentication information.
  -g, --dnscrypt-config=           Path to a file with DNSCrypt configuration. You can generate one using https://github.com/ameshkov/dnscrypt
      --edns-addr=                 Send EDNS Client Address
      --upstream-mode=             Defines the upstreams logic mode, possible values: load_balance, parallel, fastest_addr (default:
                                   load_balance)
  -l, --listen=                    Listening addresses
  -p, --port=                      Listening ports. Zero value disables TCP and UDP listeners
  -s, --https-port=                Listening ports for DNS-over-HTTPS
  -t, --tls-port=                  Listening ports for DNS-over-TLS
  -q, --quic-port=                 Listening ports for DNS-over-QUIC
  -y, --dnscrypt-port=             Listening ports for DNSCrypt
  -u, --upstream=                  An upstream to be used (can be specified multiple times). You can also specify path to a file with the
                                   list of servers
  -b, --bootstrap=                 Bootstrap DNS for DoH and DoT, can be specified multiple times (default: use system-provided)
  -f, --fallback=                  Fallback resolvers to use when regular ones are unavailable, can be specified multiple times. You can also
                                   specify path to a file with the list of servers
      --private-rdns-upstream=     Private DNS upstreams to use for reverse DNS lookups of private addresses, can be specified multiple times
      --dns64-prefix=              Prefix used to handle DNS64. If not specified, dnsproxy uses the 'Well-Known Prefix' 64:ff9b::.  Can be
                                   specified multiple times
      --private-subnets=           Private subnets to use for reverse DNS lookups of private addresses
      --bogus-nxdomain=            Transform the responses containing at least a single IP that matches specified addresses and CIDRs into
                                   NXDOMAIN.  Can be specified multiple times.
      --hosts-files=               List of paths to the hosts files relative to the root, can be specified multiple times
      --timeout=                   Timeout for outbound DNS queries to remote upstream servers in a human-readable form (default: 10s)
      --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.
      --cache-size=                Cache size (in bytes). Default: 64k
  -r, --ratelimit=                 Ratelimit (requests per second)
      --ratelimit-subnet-len-ipv4= Ratelimit subnet length for IPv4. (default: 24)
      --ratelimit-subnet-len-ipv6= Ratelimit subnet length for IPv6. (default: 56)
      --udp-buf-size=              Set the size of the UDP buffer in bytes. A value <= 0 will use the system default.
      --max-go-routines=           Set the maximum number of go routines. A zero value will not not set a maximum.
      --tls-min-version=           Minimum TLS version, for example 1.0
      --tls-max-version=           Maximum TLS version, for example 1.3
      --pprof                      If present, exposes pprof information on localhost:6060.
      --version                    Prints the program version
  -v, --verbose                    Verbose output (optional)
      --insecure                   Disable secure TLS certificate validation
      --ipv6-disabled              If specified, all AAAA requests will be replied with NoError RCode and empty answer
      --http3                      Enable HTTP/3 support
      --cache-optimistic           If specified, optimistic DNS cache is enabled
      --cache                      If specified, DNS cache is enabled
      --refuse-any                 If specified, refuse ANY requests
      --edns                       Use EDNS Client Subnet extension
      --dns64                      If specified, dnsproxy will act as a DNS64 server
      --use-private-rdns           If specified, use private upstreams for reverse DNS lookups of private addresses
      --hosts-file-enabled=        If specified, use hosts files for resolving (default: true)

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

Listen on multiple interfaces and ports:

./dnsproxy -l 127.0.0.1 -l 192.168.1.10 -p 5353 -p 5354 -u 1.1.1.1

The plain DNS upstream server may be specified in several ways:

• With a plain IP address:

  ./dnsproxy -l 127.0.0.1 -u 8.8.8.8:53
  

• With a hostname or plain IP address and the udp:// scheme:

  ./dnsproxy -l 127.0.0.1 -u udp://dns.google -u udp://1.1.1.1
  

• With a hostname or plain IP address and the tcp:// scheme to force using TCP:

  ./dnsproxy -l 127.0.0.1 -u tcp://dns.google -u tcp://1.1.1.1
  

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

DNS-over-QUIC upstream:

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

DNS-over-HTTPS upstream with enabled HTTP/3 support (chooses it if it's faster):

./dnsproxy -u https://dns.google/dns-query --http3

DNS-over-HTTPS upstream with forced HTTP/3 (no fallback to other protocol):

./dnsproxy -u h3://dns.google/dns-query

DNSCrypt upstream (DNS Stamp of AdGuard DNS):

./dnsproxy -u sdns://AQMAAAAAAAAAETk0LjE0MC4xNC4xNDo1NDQzINErR_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

Runs a DNS-over-HTTPS proxy on 127.0.0.1:443 with HTTP/3 support.

./dnsproxy -l 127.0.0.1 --https-port=443 --http3 --tls-crt=example.crt --tls-key=example.key -u 8.8.8.8:53 -p 0

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

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

Runs a DNSCrypt proxy on 127.0.0.1:443.

./dnsproxy -l 127.0.0.1 --dnscrypt-config=./dnscrypt-config.yaml --dnscrypt-port=443 --upstream=8.8.8.8:53 -p 0

Please note that in order to run a DNSCrypt proxy, you need to obtain DNSCrypt configuration first. You can use https://github.com/ameshkov/dnscrypt command-line tool to do that with a command like this ./dnscrypt generate --provider-name=2.dnscrypt-cert.example.org --out=dnscrypt-config.yaml

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 --upstream-mode parallel

Loads upstreams list from a file.

./dnsproxy -l 127.0.0.1 -p 5353 -u ./upstreams.txt

DNS64 server

dnsproxy is capable of working as a DNS64 server.

What is DNS64/NAT64 This is a mechanism of providing IPv6 access to IPv4. Using a NAT64 gateway with IPv4-IPv6 translation capability lets IPv6-only clients connect to IPv4-only services via synthetic IPv6 addresses starting with a prefix that routes them to the NAT64 gateway. DNS64 is a DNS service that returns AAAA records with these synthetic IPv6 addresses for IPv4-only destinations (with A but not AAAA records in the DNS). This lets IPv6-only clients use NAT64 gateways without any other configuration.

See also RFC 6147.

Enables DNS64 with the default Well-Known Prefix:

./dnsproxy -l 127.0.0.1 -p 5353 -u 8.8.8.8 --use-private-rdns --private-rdns-upstream=127.0.0.1 --dns64

You can also specify any number of custom DNS64 prefixes:

./dnsproxy -l 127.0.0.1 -p 5353 -u 8.8.8.8 --use-private-rdns --private-rdns-upstream=127.0.0.1 --dns64 --dns64-prefix=64:ffff:: --dns64-prefix=32:ffff::

Note that only the first specified prefix will be used for synthesis.

PTR queries for addresses within the specified ranges or the Well-Known one could only be answered with locally appropriate data, so dnsproxy will route those to the local upstream servers. Those should be specified and enabled if DNS64 is enabled.

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 --upstream-mode=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, decorating domains with brackets (see --server description).

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

Where upstreamString is one or many upstreams separated by space (e.g. 1.1.1.1 or 1.1.1.1 2.2.2.2).

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", which will be used to resolve names with a single label in them, or with exactly two labels in case of DS requests.
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 common 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.
4. The wildcard * has special meaning of "any sub-domain", so: --upstream=[/*.host.com/]1.2.3.4 will send queries for *.host.com to 1.2.3.4, but host.com will be forwarded to default upstreams.

Examples

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

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

Sends requests for *.host.com to 1.1.1.1:53 except for *.maps.host.com which are sent to 8.8.8.8:53 (along with other requests):

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

Sends requests for *.host.com to 1.1.1.1:53 except for host.com which is sent to 9.9.9.10:53, and all other requests are sent to 8.8.8.8:53:

./dnsproxy\
    -u "8.8.8.8:53"\
    -u "[/host.com/]9.9.9.10:53"\
    -u "[/*.host.com/]1.1.1.1:53"

Sends requests for com (and its subdomains) to 1.2.3.4:53, requests for other top-level domains to 1.1.1.1:53, and all other requests to 8.8.8.8:53:

./dnsproxy\
    -u "8.8.8.8:53"\
    -u "[//]1.1.1.1:53"\
    -u "[/com/]1.2.3.4:53"

Specifying private rDNS upstreams

You can specify upstreams that will be used for reverse DNS requests of type PTR for private addresses. Same applies to the authority requests of types SOA and NS. The set of private addresses is defined by the --private-rdns-upstream, and the set from RFC 6303 is used by default.

The additional requirement to the domains specified for upstreams is to be in-addr.arpa, ip6.arpa, or its subdomain. Addresses encoded in the domains should also be private.

Examples

Sends queries for *.168.192.in-addr.arpa to 192.168.1.2, if requested by client from 192.168.0.0/16 subnet. Other queries answered with NXDOMAIN:

./dnsproxy\
    -l "0.0.0.0"\
    -u "8.8.8.8"\
    --use-private-rdns\
    --private-subnets="192.168.0.0/16"
    --private-rdns-upstream="192.168.1.2"\

Sends queries for *.in-addr.arpa to 192.168.1.2, *.ip6.arpa to fe80::1, if requested by client within the default RFC 6303 subnet set. Other queries answered with NXDOMAIN:

./dnsproxy\
    -l "0.0.0.0"\
    -u 8.8.8.8\
    --use-private-rdns\
    --private-rdns-upstream="192.168.1.2"\
    --private-rdns-upstream="[/ip6.arpa/]fe80::1"

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. dnsproxy will transform responses that contain at least a single IP address which is also specified by the option 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 transform them to NXDOMAIN.

./dnsproxy -u 94.140.14.14:53 --bogus-nxdomain=0.0.0.0

CIDR ranges are supported as well. The following will respond with NXDOMAIN instead of responses containing any IP from 192.168.0.0-192.168.255.255:

./dnsproxy -u 192.168.0.15:53 --bogus-nxdomain=192.168.0.0/16

Basic Auth for DoH

By setting the --https-userinfo option you can use dnsproxy as a DoH proxy with basic authentication requirements.

For example:

./dnsproxy\
    --https-port='443'\
    --https-userinfo='user:p4ssw0rd'\
    --tls-crt='…/my.crt'\
    --tls-key='…/my.key'\
    -u '94.140.14.14:53'

This configuration will only allow DoH queries that contain an Authorization header containing the BasicAuth credentials for user user with password p4ssw0rd.

Add -p 0 if you also want to disable plain-DNS handling and make dnsproxy only serve DoH with Basic Auth checking.