DNS over TLS upstream server Docker container

DNS over TLS upstream server connected to DNS over TLS (IPv4 and IPv6) servers with DNSSEC, DNS rebinding protection, built-in Docker healthcheck and fine grain IPs + hostnames blocking

Announcement: Total rewrite in Go: see the new features below (in case something break, use the image with tag :shell)

Features

• It can be connected to one or more of the following DNS-over-TLS providers:

  • Cloudflare
  • Google
  • Quad9
  • LibreDNS
  • Quadrant
  • CleanBrowsing
  • CIRA Canadian Shield

• Split-horizon DNS (randomly pick one of the DoT providers specified for each request)

• Block hostnames and IP addresses for 3 categories: malicious, surveillance and ads

• Block custom hostnames and IP addresses using environment variables

• One line setup

• Runs without root

• Small 41.1MB Docker image (uncompressed, amd64)

  Click to show base components

  • Alpine 3.12
  • Unbound 1.10.1 built from source (from Alpine packages)
  • Files and lists built periodically
  • Go static binary built from this source

• Resolves using IPv4 and IPv6 when available

• Auto updates block lists and cryptographic files very 24h and restarts Unbound (< 1 second downtime)

• Compatible with amd64, i686 (32 bit), ARM 64 bit, ARM 32 bit v7 and ppc64le 🎆

• DNS rebinding protection

• DNSSEC Validation

  

Diagrams are shown for router and client-by-client configurations in the Connect clients to it section.

Setup

1. Launch the container with

   docker run -d -p 53:53/udp qmcgaw/dns
   

   You can also use docker-compose.yml with:

   docker-compose up -d
   

   More environment variables are described in the environment variables section.

2. See the Connect clients to it section, you can also refer to the Verify DNS connection section if you want.

Docker tags 🐳

💁 qmcgaw/cloudflare-dns-server:latest mirrors qmcgaw/dns:latest

Environment variables

Extra configuration

You can bind mount an Unbound configuration file include.conf to be included in the Unbound server section with -v $(pwd)/include.conf:/unbound/include.conf:ro, see Unbound configuration documentation

Connect clients to it

Option 1: Router (recommended)

All machines connected to your router will use the 1.1.1.1 encrypted DNS by default

Configure your router to use the LAN IP address of your Docker host as its primary DNS address.

• Access your router page, usually at http://192.168.1.1 and login with your credentials
• Change the DNS settings, which are usually located in Connection settings / Advanced / DNS server
• If a secondary fallback DNS address is required, use a dull ip address such as the router's IP 192.168.1.1 to force traffic to only go through this container

To ensure network clients cannot use another DNS, you might want to

• Block the outbound UDP 53 port on your router firewall
• Block the outbound TCP 853 port on your router firewall, except from your Docker host
• If you have Deep packet inspection on your router, block DNS over HTTPs on port TCP 443

Option 2: Client, one by one

You have to configure each machine connected to your router to use the Docker host as their DNS server.

Docker containers

Connect other Docker containers by specifying the DNS to be the host IP address 127.0.0.1:

docker run -it --rm --dns=127.0.0.1 alpine

For docker-compose.yml:

version: '3'
services:
  test:
    image: alpine:3.11
    network_mode: bridge
    dns:
      - 127.0.0.1

If the containers are in the same Docker network, you can simply set the dns to the LAN IP address of the DNS container (i.e. 10.0.0.5)

Windows

1. Open the control panel and follow the instructions shown on the screenshots below.

Enter the IP Address of your Docker host as the Preferred DNS server (192.168.1.210 in my case) You can set the Cloudflare DNS server address 1.1.1.1 as an alternate DNS server although you might want to leave this blank so that no domain name request is in plaintext.

When closing, Windows should try to identify any potential problems. If everything is fine, you should see the following message:

Mac OS

Follow the instructions at https://support.apple.com/kb/PH25577

Linux

You probably know how to do that. Otherwise you can usually modify the first line of /etc/resolv.conf by changing the IP address of your DNS server.

Android

See this

iOS

See this

Firewall considerations

This container requires the following connections:

• UDP 53 Inbound (only if used externally)
• TCP 853 Outbound to 1.1.1.1 and 1.0.0.1

Verify DNS connection

1. Verify that you use Cloudflare DNS servers: https://www.dnsleaktest.com with the Standard or Extended test
2. Verify that DNS SEC is enabled: https://en.internet.nl/connection

Note that https://1.1.1.1/help does not work as the container is not a client to Cloudflare servers but a forwarder intermediary. Hence https://1.1.1.1/help does not detect a direct connection to them.

Go API

Some packages are exposed publicly through the pkg directory.

The API is at v1.x.x but (shame on me) is not stable and subject to change without changing version. If you need it to be stable, please create an issue.

For now, it is used by the gluetun project for its DNS over TLS usage.

Development

1. Setup your environment

   Using VSCode and Docker

   1. Install Docker
      • On Windows, share a drive with Docker Desktop and have the project on that partition
      • On OSX, share your project directory with Docker Desktop
   2. With Visual Studio Code, install the remote containers extension
   3. In Visual Studio Code, press on F1 and select Remote-Containers: Open Folder in Container...
   4. Your dev environment is ready to go!... and it's running in a container 👍
   Locally

   Install Go, Docker and Git; then:

   go mod download
   

   And finally install golangci-lint

2. Commands available:

   # Build the binary
   go build cmd/main.go
   # Test the code
   go test ./...
   # Lint the code
   golangci-lint run
   # Build the Docker image
   docker build -t qmcgaw/dns .
   

3. See Contributing for more information on how to contribute to this repository.

TO DOs

• GolangCI-lint
• [ ] Periodic SHUP signal to reload block lists
• [x] Build Unbound binary at image build stage
  • [ ] smaller static binary
  • [ ] Bundled with Go static binary on a Scratch image
• [ ] Branch with Pihole bundled