Pi-Hole is a DNS based ad blocker. You can install it on a Debian based Linux distributions. To use it together with a PfSense firewall you need to change a few firewall settings:

• Login to your PfSense and go to System -> General Setup:

In the first DNS Server field insert the IP of your Pi-Hole computer and save changes

• Go to Services -> DNS Resolver:

Tick Enable DNS resolver

Tick Enable DNSSEC Support

Tick Enable Forwarding Mode (this will tell the PfSense to use a DNS server that we configured in a general settings in the previous step)

Save and that’s it.