Script toggles for DNS over HTTPS on public Wi-Fi

DNS over HTTPS has been fun to try out. I’ve been using Cloudflare’s command line client/service/proxy configuration and working through some of the quirks with day to day use.

In a nutshell: A DNS proxy is setup on your local machine that makes DNS over HTTPS requests to Cloudflare’s 1.1.1.1 and 1.0.0.1 servers. Your configured DNS server is 127.0.0.1, and lookups are encrypted between your local machine and 1.1.1.1. With this data encrypted, your service provider (home ISP, coffee shop, hotel, airport, etc…) does not see the domain name requests that are made.

This works great until you join a wireless network with some kind of captive portal requiring you to either login or accept some kind of terms. At that point, the network’s DNS is usually used to provide the address for that captive portal and no other network activity is allowed until that process completes. In many cases, this will not be compatible with a DNS over HTTPS configuration.

There are a handful of steps required for switching back and forth, which could be a pain if you’re frequently bouncing between locations.

• Enable or disable the cloudflared service
• Enable or disable the dnsmasq service (if using that to capture local .test lookups for example)
• Change the DNS configuration to either 127.0.0.1 or a default config to allow the network to serve its own DNS.

To handle this, I wrote a couple quick bash scripts that I can use to reduce my annoyance and toggle things back and forth.

The doh-enable script turns on cloudflared, turns on dnsmasq, and sets the local IP as a DNS server:

# doh-enable: enables the DNS over HTTPS config
sudo launchctl setenv TUNNEL_DNS_PORT 54
sudo launchctl load /Library/LaunchDaemons/com.cloudflare.cloudflared.plist
sudo brew services start dnsmasq
networksetup -setdnsservers Wi-Fi 127.0.0.1

The doh-disable script turns off cloudflared, turns off dnsmasq, and empties the custom DNS server config to accept the network default:

# doh-disable: disables the DNS over HTTPS config
sudo launchctl unload /Library/LaunchDaemons/com.cloudflare.cloudflared.plist
sudo brew services stop dnsmasq
networksetup -setdnsservers Wi-Fi empty

Now when I encounter a captive portal situation, all I need to do is type one command, sign in, then type another.

If you’re interested in trying out DNS over HTTPS, I found the Cloudflare documentation well written and this article helpful for getting dnsmasq running alongside it.