DNS

In order to use the dnsbl-exporter, you need a DNS resolver to query the RBLs directly.

Using public resolvers such as Google, Cloudflare, OpenDNS, Quad9 etc. will likely not work as often a NXDOMAIN response is treated different by these providers.

The recommendation is to setup a private resolver, such as Unbound without forwarding, which means you will use root NS.

Please note: If you have local copy (mirror) of RBL zone synced over rsync or other channels you can configure local rbldnsd to serve this zone and configure Unbound query this zone from rbldnsd.

To install unbound on a Mac, follow these steps:

$ brew install unbound
...
$ sudo unbound -d -vvvv

And leave the Terminal open — there will be ample queries and data for you to see and learn from.

An alternative to Homebrew is to use Docker; an example image is provided in this repository, it contains a working configuration — ymmv.

docker run -p 53:5353/udp ghcr.io/luzilla/unbound:v0.7.0-rc3

Verify Unbound works:

 $ dig +short @127.0.0.1 spamhaus.org
192.42.118.104