dns-blackhole 0.12

A generic DNS black hole zone generator

Most of code comes from here: http://git.mauras.ch/Various/powerdns_recursor_ads_blocking

Check it for history.

This script helps you create a blackhole zone for your DNS server, using some well known ads/tracking/malware lists.

As long as your DNS server allows to include a file containing one domain per line with its config syntax it should work.

Right now known to work and tested:

• Unbound
• PowerDNS recursor
• Dnsmasq

Generating an agregated host file is also possible.

Features

• Not bound to a specific DNS server, generates a file format of your choice
• Supports 3 different list format
  • Host file
  • Easylist
  • Disconnect
• Lets you whitelist/blacklist domains
• YAML configuration file

Installation

The script requires PyYAML and requests modules.

pip install [--upgrade] dns-blackhole

Unbound

Requires unbound >= 1.6, using the default zone file with unbound 1.5 will certainly make it eat all your ram and swap before getting killed.

Add include: "/etc/unbound/blackhole.zone" right after your server: block.

Use the following zone_data in your dns-blackhole.yml (default):

zone_data: 'local-zone: "{domain}" always_nxdomain'

{domain} wil be replaced by the blackholed domains

PowerDNS Recursor

Add forward-zones-file=/etc/pdns/blackhole.zone in your recursor configuration.

Use the following zone_data in your dns-blackhole.yml:

zone_data: '{domain}='

{domain} wil be replaced by the blackholed domains

Dnsmasq

Add conf-dir=/etc/dnsmasq.d in your dnsmasq config and point your zone_file option to /etc/dnsmasq.d/blackhole.conf

Use the following zone_data in your dns-blackhole.yml:

zone_data: 'server=/{domain}/'

{domain} wil be replaced by the blackholed domains

Host file

Use the following zone_data in your dns-blackhole.yml:

zone_data: '127.0.0.1 {domain}'

Once you’re happy with your configuration Just run dns-blackhole.

The default lists in dns-blackhole.yml will generate a zone containing ~698000 entries.

Configuration

As the configuration file is in YAML, you can use YAML anchors

dns-blackhole:
  general:
    cache: /var/cache/dns-blackhole
    log: /var/log/dns-blackhole/dns-blackhole.log
    whitelist: /etc/dns-blackhole/whitelist
    blacklist: /etc/dns-blackhole/blacklist
    blackhole_lists:
      hosts:
        - http://someonewhocares.org/hosts/hosts
        - https://hosts-file.net/download/hosts.txt
        - http://winhelp2002.mvps.org/hosts.txt
        - http://www.malwaredomainlist.com/hostslist/hosts.txt
        - https://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts;showintro=0
      easylist: &bh_easy
        - https://easylist.to/easylist/easylist.txt
        - https://raw.githubusercontent.com/paulgb/BarbBlock/master/BarbBlock.txt
      disconnect: &bh_disconnect
        url: https://services.disconnect.me/disconnect-plaintext.json
        categories: # Advertising, Analytics, Disconnect, Social
          - Advertising
          - Analytics
  config:
    zone_file: /etc/unbound/blackhole.zone
    # {domain} will be replaced by the blackholed domain, do not change it here
    zone_data: 'local-zone: "{domain}" always_nxdomain'
    blackhole_lists:
      hosts:
        - http://winhelp2002.mvps.org/hosts.txt
      easylist: *bh_easy
      disconnect: *bh_disconnect

In this example you would keep easylist and disconnect lists, but would remove all host file lists except mvps.

FAQ

What’s the advantage of having the DNS server returning NX instead of 127.0.0.1

Host lists are usually returning 127.0.0.1 or 0.0.0.0.

Depending of the system and/or browser you use, you can end up having timeout/slowness issues as it retries to connect several times before considering the remote resource down.

Having your DNS server return NXDOMAIN - Non existant domain - on the other side makes your client behave faster as there’s nothing to retry when the domain doesn’t exist.

Why using forward-zones-file option instead of auth-zones in PowerDNS recursor?

Syntax of the auth-zones is like this: auth-zones=dom1=<zone>,dom2=<zone>,dom3=<zone>,etc

While this may work for 5000 black holed domains, for almost 700 000 the speed of generation is so slow that it takes several tens of minutes to complete. Even worse, with such a list, pdns-recursor is not even able to start and will crash.

By using the forward-zones-file pdns-recursor takes around 5 more seconds to process the zone file.

Which DNS server is the best?

It’s really a matter of preferences and what you have available. Use the one you’re the most comfortable with.

TODO

• Cache is not implemented yet
• Log is not implemented yet