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!

Fourth Step: Adlists

Okay, phew! Crisis averted. Just some missing networking knowledge. So what's next up on the list? Hmmm... Let's see... The default adlist is kinda small, let's go see if we can find some new adlists. Apparently this is more difficult than you'd think. A quick search on DDG only came up with an equivalent search in GitHub. Not useful! I have no idea the trustworthiness and stability of these adlists. Let's see. Another search leads to a Reddit article that then links to a different list. Bingo! An Adlist list. Exactly what I needed. I went ahead and looked into these lists, and added a few of them. Perfect!

Fifth Step: Maintenance

docker compose pull && docker compose up -d
Of course, this isn't it. I actually use an a/b update scheme, but you get the gist. Updates are taken care of, and just make sure you try and keep the server up as long as possible, and keep downtime to a minimum.

Sixth Step: Moving off the NAS.

After a while of running this, the necessity of having the NAS on the whole time was starting to get frustrating. The answer there was to move it off the NAS. I did this by installing it on a Raspberry Pi 3B, running Arch Linux ARM. The setup was identical to before once I had gotten ALARM running.