Get a DDNS up and running with DuckDNS - Step by Step

Understanding DDNS

DDNS stands for Dynamic DNS. It updates a DNS name in real time so that it points to a changing IP address. This is useful for devices without a static IP.

Static IPs and IP ranges can be expensive. DDNS provides a cost-effective alternative by linking a hostname to a dynamic IP address.

How DDNS works

To use DDNS, you need an account with a DDNS provider. A script or service on your device updates the DDNS provider with your current IP at regular intervals, keeping the hostname linked to the right address.

DuckDNS is free and relies on donations to keep its services running. If you find it useful, consider supporting DuckDNS on Patreon.

Setting up DuckDNS

1. Create an account and log in. Visit DuckDNS and log in or create an account.

   

2. Create a domain. Once logged in, create a domain and link it to your current public IP.

   

Automating IP updates with a script

DuckDNS provides a simple script to keep your domain updated. You can follow their guide or continue with the steps below.

1. Ensure crontab is running:

   ps -ef | grep cr[o]n
   

2. Check that curl is installed:

   curl --version
   

   If it is not installed on Ubuntu or Debian, install it with:

   sudo apt install curl -y
   

3. Create a DuckDNS script. Navigate to your home directory and create a duckdns folder:

   cd ~
   mkdir duckdns
   cd duckdns
   touch duck.sh
   

4. Edit the script. Open duck.sh with nano or your preferred editor and add:

   #!/bin/bash
   DOMAIN="EXAMPLE"
   TOKEN="TOKEN"
   echo url="https://www.duckdns.org/update?domains=$DOMAIN&token=$TOKEN&ip=" | curl -o ~/duckdns/duck.log -K -
   

   Replace EXAMPLE with your DuckDNS domain and TOKEN with the unique token shown at the top of the DuckDNS dashboard.

5. Set permissions and schedule the script. Make it executable:

   chmod +x ~/duckdns/duck.sh
   

   Open the crontab editor:

   crontab -e
   

   Add this line to run the script every five minutes:

   */5 * * * * ~/duckdns/duck.sh >/dev/null 2>&1
   

6. Run the script manually for the first time:

   cd ~/duckdns/
   ./duck.sh
   

   Check duck.log. If it contains OK, the setup succeeded. If it contains KO, review the domain, token, permissions, and command before continuing.

Next steps

For example, you may want to set up port forwarding on your router to make effective use of the new DDNS hostname.