OpenWrt is an amazing open source OS for routers. Today we're looking at how to set up dynamic DNS to Cloudflare on it.
Dynamic DNS is simply a service running on your router in a fixed interval (i.e. every hour) that updates your DNS record to point to the current IP address. This is pretty common for servers setups where the publicly accessible IP often changes, making manual updates not viable.
Cloudflare is commonly used for managing DNS, since it's free, pretty stable and provides great UX through the web-UI and programmatic API. We'll first have to get an API token that allows our DDNS service to update DNS records through the API. All we need to set this up is a working router with OpenWrt running on it and a Cloudflare account with a configured domain name.
This article will focus on IPv4, but you can still follow along for IPv6 and change some details in the configuration assuming you have some basic understanding of the tech.
First, let's create a new DNS entry that will later be dynamically updated to point to the
current public IP of the server. After logging in, navigate to
yourdomain > DNS > Add record and add a new A (Ipv4) record.
I'll be assigning mine to a subdomain (i.e. subdomain.domain.com), but feel free to use
the root of the domain instead. I'll point it to 0.0.0.0 for now and disable Cloudflare
proxying since it prevents me to SSH into the server (important: your IP will be publicly
visible if you disable the proxy).
The next step is to create a new API token by visiting the
User API Tokens page
and clicking the Create Token button.
Create a custom token and give it a name and the following permissions:
And select the following resource:
Now continue and press the Create Token button. Once the token is created, copy it to a
secure place such as a password manager. If you forget your token in the future, you'll have
to create a new one and re-configure the DDNS service we'll set up momentarily.
Now that we have a Cloudflare API token, let's configure the router. Log into the web-UI and
navigate to the System > Software section, so we can install some packages that will make DDNS work.
Click on Update lists... button to refresh the list of available packages.
Into the filter search bar, type ddns and install both the ddns-scripts and
ddns-scripts-cloudflare packages as shown in the picture.
After installing both packages, reboot the router in System > Reboot and wait for it
to boot up. Once that's done, log back in and you should see a new section in the header
navigation called Services. Navigate to Services > Dynamic DNS so we can input the
necessary Cloudflare account details.
This is the last step, we simply need to input all necessary data to create our DDNS service.
First click Add new services... button, give it a name and set the following settings:
cloudflare.com-v4After saving the service, go to Status > Overview and check whether the router knows
its current public IPv4 address. If it does, you're done, feel free to skip ahead.
In my case it does not, as you can see here:
As you can see, there's only 192.0.0.2 listed, which is not the public IP.
Due to this, we need to use an external service for getting our IP address.
Luckily this is easily done by going back to Services > Dynamic DNS and
editing our DDNS service from earlier, then going to the Advanced Settings tab
and setting:
IP address source to URLURL to detect to http://checkip.dyndns.com (or alternatives)Once we're done with configuring the service, reload it by hitting the Reload button
next to the service name and finally Restart DDNns at the top of the page to ensure
everything is running with the latest settings.
When editing our service, we can check the Log File Viewer tab to see the
logs and make sure everything is working as it should. If you see any errors,
check your configuration and ensure you filled the login fields correctly.
Finally try accessing your server through the domain/subdomain we just configured -
if it works you're done 🎉.