Adding Wildcard Subdomain Support to macOS

I needed to set up wildcard subdomain support for my home network, this is how I did it

Originally published on my website

For several years now, I’ve been using IP addresses and ports to access services that I run on my home server. However, I decided it was time to switch to using a domain instead. I had heard about Traefik and Caddy in r/HomeServer and r/homelab and chose to try out Traefik, mainly because it had native support for Docker labels.

The first few steps involved installing Traefik with Docker, adding HTTPS support through Let’s Encrypt, and reconfiguring my web containers to use it. The next step was to add a dnsmasq rule to my Pi-hole so that all requests would be redirected to the subdomain I chose (I used servername.mydomain.com as the base host in Traefik). However, on my Mac, I'm not always using my Pi-hole's DNS, usually when I need to circumvent the ad-blocking. I accomplish this through macOS' native support for network locations.

After doing a bit of research, I found out I could use dnsmasq on my Mac to do accomplish wildcard subdomains, just like I did on the Pi-hole, but it worked wonderfully once I got it to work.

I used Homebrew to install and configure dnsmasq: brew install dnsmasq. I then opened the configuration file for dnsmasq from its place in /usr/local/etc/dnsmasq.conf and added the line below. If you changed the location of your Homebrew install, run brew --prefix, then replace /usr/local with the value.

address=/servername.mydomain.com/10.90.100.1

This line configures the routing, and redirects all requests made to servername.mydomain.com and its subdomains to 10.90.100.1. Make sure to replace 10.90.100.1 with the IP you want to redirect to. If you're interested in knowing why dnsmasq redirects all redirects to both the base domain and its subdomains to the IP, this Stack Overflow answer explains why.

To start dnsmasq, run sudo brew services start dnsmasq. Homebrew will handle autostarting the daemon and ensuring it stays alive. I found this to be simpler than the common method of copying the Homebrew launch daemon plistto /Library/LaunchDaemons and manually telling launchctl to load it.

If you were to try running a command such as ping to see if your wildcard subdomain redirection worked, you'd be sorely disappointed, because there's one more step. I found it easiest to use the GUI for this. Open the Network panel in System Preferences, click "Advanced", and go to the "DNS" tab. Click the plus button and type in 127.0.0.1 and then hit enter. For more information on 127.0.0.1, check out its Wikipedia article. Back to System Preferences, click the OK button, then click Apply. Once the icon is disabled and greyed out, flush your DNS cache. You can do that with sudo dscacheutil -flushcache and sudo killall -HUP mDNSResponder. Now, try your ping command again, and you should get a response. If it does, try accessing the service through your browser.

If you have any questions or need any help, feel free to contact me on Twitter or Mastodon.

I hope that this article is useful for you! Thank you for reading!