HPR4281: My ridiculously complicated DHCP setup at home

Hacker Public Radio

Hello, this is Jon The Nice Guy, and after 10 years of knowing about Hacker Public Radio, here is my first podcast for the network. Firstly, I want to give a shout out to my Admin Admin Podcast co-host Al, who I heard just a week-or-so ago talking about Proxmox! Glad to hear you're over here too! I wanted to record an episode on my ridiculously complicated DHCP setup at home. I'm not saying this is the right or even a good idea for anyone else, but it's something you might want to do. Firstly, a little about why I have a complicated DHCP setup, and it starts with the router my previous ISP gave me. My router could just about cope with serving DHCP, but at the time when I was experimenting with running services on my home lab, the DNS server on the router wouldn't return addresses for hosts on my network, just those on the public internet. This wasn't a great experience! So, I installed PiHole [1] - initially because I'd heard good things about it's ad blocking capabilities, but later because it was just a pretty and sensible DHCP and DNS server that I could do things with. Under the covers, PiHole is running DNSMasq [2], which means that all the configuration is plain text files that I can overwrite with Ansible [3]. My PiHole was running on a Raspberry Pi 2 [4], in a lego-style case [5] plugged into the back of my router. And this was fine for a few months. And then it ran out of storage space, I changed jobs, my wife complained one too many times, and I reverted back to using the router's DHCPd and DNS. I also picked up either Nebula [6] or Tailscale [7] at around that time too, so I didn't need internal DNS to resolve to home services any more, and anything public I setup external DNS records pointing to the internal addresses. Job done. Scrub forward a couple of years, and when I changed jobs, I got a joining bonus which paid for me to get wired network around my house. I also setup my own Proxmox [8] cluster, which I documented on a post [9] on my blog [10]. Again, everything was peachy. I setup home assistant [11], which I expose on to the internet via a proxy on my VPS, and everything was still good... but things are a little more complicated now - I've got more stuff to keep track of and the router's DHCP server was struggling a little... but it was all OK. And then I changed ISP. My new ISP shipped a router running a customized version of OpenWRT [12], and I thought, finally, a good router! And then I realised I couldn't do *anything* sensible with it. It was so locked down, I couldn't even change the admin password without factory resetting it! Ugh. Within a couple of weeks my wife was complaining about random intermittent DNS requests failing, and I was seeing it too. So, I found on the Proxmox Helper Scripts [13] website that someone had put a script to setup a PiHole instance... So naturally, as I had two Proxmox Servers by this point, I ran two PiHole servers. This lasted a few months until I performed a system upgrade to the proxmox cluster and it took down both Proxmox cluster members at the same time and DNS fell off the network! I revived the Raspberry Pi 2 which now sits attached to the router again! Yes! Meanwhile, I was now getting more into IoT and I had several Tuya IoT devices connected over Wifi, and the 254 network addresses available in the /24 sized network [14] to me at home didn't seem enough, so I decided to expand my network to a /22, giving me enough address space for 1022 devices. Plus, I have kids, who each have computers and phones and games devices, my wife and I both work from home, so we both have computers from work and our own devices too... so I de