donutdns

README

donutdns

Block online ads by intercepting DNS queries

Project Overview

The github.com/shoenig/donutdns module provides a CoreDNS plugin as well as a standalone executable DNS server that can be used to block DNS queries to domains used by online advertisers, trackers, scammers, and crypto miners. The project is meant to be a simpler alternative to the venerable Pi-Hole. In particular, donutdns is easy to run as a non-root Docker container with little to no configuration.

sample logs

[INFO] plugin/donutdns: BLOCK query (A) for www.google-analytics.com.
[INFO] plugin/donutdns: BLOCK query (A) for www-google-analytics.l.google.com.
[INFO] plugin/donutdns: BLOCK query (AAAA) for stats.wp.com.
[INFO] plugin/donutdns: BLOCK query (A) for www.googletagservices.com.
[INFO] plugin/donutdns: BLOCK query (A) for tpc.googlesyndication.com.
[INFO] plugin/donutdns: BLOCK query (A) for c.amazon-adsystem.com.
[INFO] plugin/donutdns: BLOCK query (AAAA) for static.ads-twitter.com.

Domain Block Lists

The default set of blocked domains are retrieved from the source lists in sources.json. These lists are compiled and maintained by volunteers; see their respective headers for more information about terms of use and other metadata. Thank you to those who contribute to these domain block lists.

The blocking of the default set of domains can be disabled by setting DONUT_DNS_NO_DEFAULT=1.

Additional domains can be blocked by donutdns by setting the DONUT_DNS_BLOCK and/or DONUT_DNS_BLOCK_FILE environment variables.

Likewise, domains can be explicitly allowed by setting the DONUT_DNS_ALLOW and/or DONUT_DNS_ALLOW_FILE environment variables. The allow lists take precedense over the block lists.

For nasty companies like Facebook with dynamic subdomains, donutdns supports blocking domains by suffix matching. By setting DONUT_DNS_SUFFIX and/or DONUT_DNS_SUFFIX_FILE any query matching the given suffix(es) will be blocked.

Getting Started

donutdns can be used as a CoreDNS Plugin or standalone DNS Server.

DNS Server

The donutdns executable uses environment variables for configuration.

Environment Variable	Description
DONUT_DNS_PORT	The port to listen to (default 5301)
DONUT_DNS_NO_DEBUG	Disable CoreDNS debug logging (default unset)
DONUT_DNS_NO_LOG	Disable CoreDNS logging (default unset)
DONUT_DNS_ALLOW	Comma separated list of domains to NOT block (default unset)
DONUT_DNS_ALLOW_FILE	File with list of domains to NOT block (default unset)
DONUT_DNS_BLOCK	Comma separated list of domains to block (default unset)
DONUT_DNS_BLOCK_FILE	File with list of domains to block (default unset)
DONUT_DNS_SUFFIX	Comma separated list of domains to block by suffix (default unset)
DONUT_DNS_SUFFIX_FILE	File with list of domains to block by suffix (default unset)
DONUT_DNS_NO_DEFAULTS	Disable blocking of default domain block lists (default unset)
DONUT_DNS_UPSTREAM_1	Fallback DNS Server for non-blocked queries (default 1.1.1.1)
DONUT_DNS_UPSTREAM_2	Fallback DNS Server for non-blocked queries (default 1.0.0.1)
DONUT_DNS_UPSTREAM_NAME	Fallback DNS Server TLS name (default cloudflare-dns.com)

CoreDNS Plugin

The donutdns CoreDNS plugin is configured using the donutdns block in a standard CoreConfig configuration file.

Minimal donutdns plugin configuration. defaults can be set to true or false to enable or disable the use of default domain block lists.

donutdns {
  defaults true
}

This configuration uses block_file to explicitly block a set of domains listed in a file on local disk.

donutdns {
  defaults false
  block_file /etc/blocked-domains.txt
}

This configuration uses block and allow to explicitly block and allow certain domains.

donutdns {
  defaults true
  block facebook.com,www.facebook.com,m.facebook.com,fb.com
  allow example.com
}

When using donutdns as a CoreDNS plugin, the fallthrough behavior must be configured as desired using one or more other plugins. To recreate the same recursive behavior as the standalone executable, use the forward plugin.

forward . 1.1.1.1 1.0.0.1 {
  tls_servername cloudflare-dns.com
}

Custom block file

The file format for block_file or DONUT_DNS_BLOCK_FILE is simply a newline delimited list of domains. Empty lines and lines beginning with # are always ignored. All other lines are scanned with a regular expression to find the first plausible domain name in the line. social-media.list contains an example file for blocking facebook, instagram, and whatsapp.

# An example block list
example.com
www.example.com

Run

as an executable

With no configuration, donutdns will use the built-in domain block lists by default.

$ donutdns

Use the environment variables described above to configure things.

$ DONUT_DNS_PORT=5533 DONUT_DNS_NO_DEBUG=1 donutdns

as a systemd unit

The donutdns.service file provides an example Systemd Service Unit file for running donutdns via systemd.

# A minimal unit file, see donutdns.service for more.

[Unit]
Description=Block ads, trackers, and malicioius sites using DonutDNS.

[Service]
ExecStart=/opt/bin/donutdns
Environment=DONUT_DNS_PORT=53

[Install]
WantedBy=multi-user.target

Typically this file would be created at /etc/systemd/system/donutdns.service.

Register the new unit with sudo systemctl daemon-reload

Enable the service with sudo systemctl enable donutdns.service

Start the sevice with sudo systemctl start donutdns

Check the service with sudo systemctl status donutdns

as a docker container

donutdns is available from Docker Hub

This will run the donutdns Docker container as the nobody user, mapping traffic from port 53.

docker run --rm -p 53:5301 -u nobody shoenig/donutdns:v0.1.2

as a Nomad job

using docker driver

job "donutdns" {
  datacenters = ["dc1"]

  group "donut" {
    network {
      mode = "bridge"
      port "dns" {
        static       = 53
        to           = 5301
        host_network = "public"
      }
    }

    task "dns" {
      driver = "docker"
      user   = "nobody"

      resources {
        cpu    = 120
        memory = 64
        disk   = 128
      }

      env {
        DONUT_DNS_NO_DEBUG   = 1
        DONUT_DNS_BLOCK_FILE = "/local/blocks.txt"
      }

      config {
        image = "shoenig/donutdns:v0.1.2"
      }

      template {
        destination = "local/blocks.txt"
        change_mode = "restart"
        perms       = "644"
        data        = <<EOH
# [example]
example.com
www.example.com
EOH
      }
    }
  }
}

Troubleshooting

Certain systems (looking at you RHEL/CentOS) make running a useable DNS server particularly difficult. On my homelab CentOS 9 system I had to disable ipv6 at the kernel level, disable SELinux, and disable firewalld. You may need to do something similar (ideally updating rules rather than disabling things) on your system.

Build

The donutdns standalone DNS Server is written in Go. It can be compiled and installed using the normal Go toolchain in one step.

go install github.com/shoenig/donutdns@latest

Contributing

The github.com/shoenig/donutdns module is always improving with new features and bug fixes. For contributing such bug fixes and new features please file an issue.

License

The github.com/shoenig/donutdns module is open source under the BSD-3-Clause license.

Documentation

Overview

Command donutdns implements a network level ad-blocking DNS server.