Configuring DDNS on OpenWrt

Since IPv4 resources are very abundant in North America, purchasing a home network plan in Canada typically comes with a public IP. However, ISPs frequently change IP addresses. DDNS binds your home’s public IP to your domain name, so you can always find your home regardless of IP changes.

Prerequisites

A domain name
A public IP address
Some packages:
- ddns-scripts-cloudflare
- luci-app-ddns
- drill

Configuration Steps

First, create an A record in Cloudflare. Choose a domain like vpn.kyxie.me. The IP address can be anything for now, as it will be overwritten by DDNS later. Set Proxy status to DNS only (no proxy).
Click here to create a dedicated API token.
Select “Edit Zone DNS” and click “Use Template”.
Configure as shown below:
After generating the API token, save it carefully as it will only be displayed once.

Go to OpenWrt → Service → Dynamic DNS → Services and add a ddns_ipv4. Below is the detailed configuration. Note: you must install ddns-scripts-cloudflare first to find cloudflare.com-v4 in the DDNS Service provider dropdown.

ddns:
  "Enabled": true
  "Lookup Hostname": "vpn.kyxie.me"
  "IP address version": "IPV4-Address"
  "DDNS Service provider": "cloudflare.com-v4"
  "Domain": "[email protected]"
  "Username": "Bearer"
  "Password": "Your API Token"
  "Use HTTP Secure": true
  "Path to CA-Certificate": "/etc/ssl/certs"

If OpenWrt is your main router, DDNS resolution should work now. However, if OpenWrt is a bypass router, the WAN port won’t know the public IP. We need to get the public IP from an external website. Go to Service → Dynamic DNS → Services → ddns_ipv4 → Edit → Advanced Settings → IP address source and select “URL”. For URL to detect, you can use the default IPv4 URL: http://checkip.dyndns.com
DDNS configuration is now complete. Even if your ISP changes your public IP, your domain will still work.
After configuration, you can check Cloudflare to see if the IP has been updated.