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Access your Synology NAS with a custom domain on (DDNS)

This article is born because does not support Dynamic DNS (for the moment?), I contacted the support but I received a negative result:

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I wanted to migrate all my domain from OVH/Cloudflare to Bunny, because their DNS performances are on the top chart (they are the best?), it's free, the UI/UX of the admin panel is clean, and MOST OF ALL: They got rabbits EVERYWHERE.

However there is a big problem: to access my Synology NAS through a custom domain name, DDNS is required because:

  • My internet provider changes IP everytime the Internet Box restarts, so I have to notify my DNS provider of the new IP!
  • My internet provider doesn't give fixed IPV4 for free (to be honest I won't pay).

After experimenting, I created a Node script executed regularly on my NAS that:

  • Save the current IP of the NAS in a cache.
  • 5 Minute later, fetch the current IP and compared it with the cached IP: if the IP is different, I call the Bunny DNS API to update the DNS records value with the new IP! Finally save the new IP on the cache.
  • Repeat this process 5 Minute later: compare the current IP and cache IP again, etc...

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Bunny Setup

First, make sure you have loaded your domain on your Bunny admin interface, if not, here is the setup link:

Create a A Record and set the public IP of your Synology NAS. If the IP is not correct, it will be corrected with the Node Script on the next section:

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In my case, I have a subdomain pointing to my Synology NAS. The Value column shows the IP you entered (in my case I prefer to keep it private :D).

Finally on your Bunny account, get you API key, it will be use to update the IP of your A Record:

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Synology Setup

Synology NAS has Node already installed, so I decided to create a Node Script instead of a Bash script, copy the following file to the directory of your choice. Personnally, I copied to /volume1/home/admin/ddns-bunny.js:

Let's create a new Task executing the Script regularly, like every minutes.

  1. Open the Control Panel application > Click on Task Scheduler
  2. On the bar, click on Create > Schedule Task > User Defined Script Image description
  3. Name the new Task like DDNS Bunny and select a User, like the admin. Image description
  4. Now select the second tab Schedule: Ensure the Run on the following day is selected, and set at Daily. Image description
  5. On the second tab Schedule: Set the start time at midnight, and check Continue running the same day. Set the Repeat into to 1 minutes and Last Run Time to 23h55. Image description
  6. Now select the third tab Task Settings, and add to the "User Defined Script"the following command. BUNNY_ACCESS_KEY="" NAS_URL="" node /volume1/homes/admin/ddns-bunny.js. The command must written in one single line, otherwise the API KEY and the URL won't be retrieved by the script. Write your Bunny API key under the first double quotes for the environment variable BUNNY_ACCESS_KEY. Then write the domain of your NAS between the second double quotes for the env NAS_URL, without https://. Finally the command execute the Script with Node. Image description
  7. To verify if the script is working, enable the option "Send Run details by emails" and provide your email. Image description
  8. Save the new task, then wait one minute, to verify if everything went fine:
    • Check the email you received: it should print OK {YOUR PUBLIC IP}. If something went wrong, it should print an error message detailing the issue. Image description
    • A configuration file has been created: Open the directory /volume1/homes/admin/, and you see a JSON file named DDNS_BUNNY_CONFIG.json. It is used to save: your current public IP, and metadata to requests the Bunny API.
    • Visit your custom domain: Your Synology panel should load
    • Verify the IP: open your Bunny DNS panel, you should see the public IP of your NAS
    • If you didn't received email: You probably didn't configure right your NAS to send emails.

Known limitations

  • The script can update only one domain at the moment, I'm working on supporting multiple domains.
  • The script lacks of Unit Tests


Now supports DDNS by simply requesting their DNS API, and I can migrate all my domains to Bunny, youhouuu 🐰🎉

Top comments (3)

steeve profile image
Steeve • Edited

To create this article, I passed:

  • 3h Experimenting with my Synology NAS and the Bunny API, and writing the Node DDNS Script two times.
  • 1h30 writing: Find the article structure, writing, and prepare examples.
  • 15 minute: Find a perfect image for the banner, I used Adobe Firefly with the following prompt: "A scientist astronaute bunny conduct experiments with different flavors of carrot juice, there is multiple carrot-powered rocket and a leaf umbrella in the background. Inside of a spaceship with neons, windows all around and behind with a view on planet earth and other planets, carrots are floating due to gravity, the stars are reflecting on windows."
heyeasley profile image
heyeasley 🍓🥭


steeve profile image

Important Tips for people who want to use Bunny DNS servers with OVHCloud as a domain register:

I had a DNS propagation issue; I was not able to reach my servers for a week. After a lot of investigation, I contacted the Bunny support, and we found the issue.

On the OVHCloud admin panel, make sure you have:

  • Disabled DNSSEC: The "DNSSEC" is enabled by default on all domain on OVHCloud, that's a security option I didn't notice and never heard about. I just turned the option off, and it says it would take 24 hours to be fully disabled. (screenshot 1)
  • Deleted all DS records: Even if you disable DNSSEC, DS records are not deleted automatically. It contain a hash of a DNSKEY record, which helps verify the authenticity of DNS responses, which are expected to be OVH. However, I want to use Bunny as DNS. Just delete those dam annoying records. (screenshot 2)

Ten minutes later, the problem was solved: I can now access my server with my domains powered by Bunny DNS.

OVHCloud DNSSEC option

OVHCloud DS Record Tab