Adventures in Pi-Hole

Hi all! Today I'm gonna be talking about my adventures in setting up

Pi-hole. This will be without screenshots, but instead in all text,

sorry! Also this is all written as kind of an "Aftermath" story. This is

being written after the fact, so this might be missing some details, but

most of it is there.

Intro: What is Pi-hole

Pi-hole is a DNS/DHCP server that

allows for easy network-wide ad-blocking, along with all the nice

customizations that come with being a DNS server, such as custom

domains.

First Step: Get it running

The first step was getting Pi-hole running. I did this using Docker

Compose on a "NAS" which is honestly a full on server at this point. A

quick copy/paste from Pi-hole's

README and I was up and running! I set a singular system to use this

as a DNS server, and after that, I figured I was set and ready to

go.

Second Step: DHCP town

Of course, I wasn't satisfied just finishing there. I want automatic

DNS setting for any device that connects to my network. Of course, I

could just set the DNS upstream in my OpenWRT router to use the IP address of

my server, but that isn't good enough for me. This means I'd be missing

out on automatic per-client information, since when setting a DNS server

for OpenWRT, it only sets itself to forward any DNS requests up to the

DNS server, which means from Pi-hole's perspective, all the requests are

coming from the router and nowhere else. The solution is to set up

Pi-Hole as a DHCP server. Keep in mind this isn't a tutorial, so let's

go through what I did first. The first step was to turn on the DHCP

server in Pi-Hole. This was super easy, just a checkbox and click save.

Cool! Then I disabled the DHCP server in OpenWRT, and that was all set.

A few restarting of network devices later, like my phone, and they

automatically connected to the Pi-Hole server, and worked like a charm.

Next up, I set up Tailscale. I use Headscale, but the setup is

essentially the same as if you were using Tailscale's UI. Set in the

config to override local DNS, set the nameserver to the Tailscale IP

address of the server, and turn on magic DNS, et voila! Now to restart

the Tailscale nodes, and make sure that on the server, you set it to not

accept the DNS from Tailscale. If you don't do that, it'll get in an

endless loop of trying to use itself as the DNS server, and it's just no

good. Okay! It's all set, and I check the dashboard, and it's already

blocking DNS requests. Perfect!

Third Step: Whoopsies!

This was fine and great, but when I went to reboot my server, which I

do weekly, something bad happened. The interface for the server didn't

come up. This is a problem, since it's the DHCP server for my network,

so without that working, the network was dead in the water. It can't

give out IP addresses. What's going on? I go ahead and access my server

directly. No matter how hard I try, it can't connect to the interface.

What's the big deal? Well this is pretty simple, and a question popped

in my head that go me there. "How does this server even get its IP

address?" You see when I set up pi-hole, it just kept using the IP

address that the router gave it, which it was more than happy to use,

but the moment the router didn't have a DHCP server, the NAS didn't have

a way to get an IP address anymore. So what do you do then? The answer

is pretty simple. Give the server a static IP. Make sure in the DHCP

server of pi-hole, you set a reservation in it for the server, then in

NetworkManager, which I use, set it to have a static IP, and set its DNS

to point to localhost. Perfect! This works like a charm!