How to run DuckDNS on Raspberry Pi?

 Here’s a clean, reliable way to run DuckDNS on a Raspberry Pi. You can use either a tiny systemd timer (my pick) or a classic cron job. Both call DuckDNS’s HTTPS update API.

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0) Get your DuckDNS domain + token

1. Sign in at DuckDNS, add a subdomain, copy your token. 

2. DuckDNS update API (HTTPS) accepts:
   https://www.duckdns.org/update?domains=<DOMAINS>&token=<TOKEN>[&ip=][&ipv6=][&verbose=true]
   Leave ip= blank to auto-detect IPv4; add ipv6= if you want to set IPv6 explicitly. 

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Option A — systemd service + timer (every 5 minutes)

1) Make the updater script

sudo mkdir -p /usr/local/lib/duckdns
sudo nano /usr/local/lib/duckdns/update.sh

Paste (edit the two variables):

#!/usr/bin/env bash
DOMAINS="yourdomain1,yourdomain2"   # comma-separated, no .duckdns.org
TOKEN="your-token"

# Optional: detect a global IPv6 (uncomment next line if you want IPv6 set too)
# IPV6_ADDR=$(ip -6 addr show scope global | awk '/inet6/{print $2; exit}' | cut -d/ -f1)

URL="https://www.duckdns.org/update?domains=${DOMAINS}&token=${TOKEN}&ip=&verbose=true"
# If you set IPV6_ADDR above, append:  &ipv6=${IPV6_ADDR}

curl -s "$URL" | logger -t duckdns

Then:

sudo chmod +x /usr/local/lib/duckdns/update.sh

2) Create a service + timer

sudo nano /etc/systemd/system/duckdns.service

[Unit]
Description=DuckDNS updater

[Service]
Type=oneshot
ExecStart=/usr/local/lib/duckdns/update.sh

sudo nano /etc/systemd/system/duckdns.timer

[Unit]
Description=Run DuckDNS updater every 5 minutes

[Timer]
OnBootSec=30s
OnUnitActiveSec=5min
AccuracySec=30s
Unit=duckdns.service

[Install]
WantedBy=timers.target

Enable + test:

sudo systemctl daemon-reload
sudo systemctl enable --now duckdns.timer
systemctl list-timers | grep duckdns
sudo systemctl start duckdns.service && journalctl -u duckdns.service -n 20 --no-pager

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Option B — cron job (official DuckDNS method)

Create the same script (e.g., ~/duckdns/duck.sh) that calls the DuckDNS update URL with your domains and token, then run it via cron every 5 minutes. The DuckDNS install page shows the Linux-cron approach and using curl for the HTTPS update. 

Example:

mkdir -p ~/duckdns
nano ~/duckdns/duck.sh

#!/usr/bin/env bash
echo url="https://www.duckdns.org/update?domains=yourdomain&token=your-token&ip=&verbose=true" \
 | curl -s -k -o ~/duckdns/duck.log -K -

chmod 700 ~/duckdns/duck.sh
(crontab -l; echo "*/5 * * * * ~/duckdns/duck.sh >/dev/null 2>&1") | crontab -

A Raspberry Pi–specific walk-through of the same idea (script + cron) is here if you want a reference. 

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Optional — Docker instead of scripts

If you’re already using Docker/Compose on the Pi, the LinuxServer.io duckdns container will auto-update your IP. Their docs show the required environment variables (SUBDOMAINS, TOKEN) and a simple compose file. 

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IPv6 notes (if you want AAAA records updated)

DuckDNS supports setting IPv6 explicitly via &ipv6=<addr> in the same update call. Combine that with a one-liner that extracts your Pi’s global IPv6 (see the commented line in the script above). If you omit ipv6=, only A (IPv4) is updated; adding ipv6= sets AAAA too. 

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Verify it worked

• Run your updater once manually and look for OK in the output/log.

• Check your domain at https://www.duckdns.org—the current IP(s) should match your WAN/IPv6. 

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Troubleshooting

• No updates? Manually run the script and print the URL/response (--verbose=true helps). API syntax reference is on DuckDNS’s spec page. 

• Cron didn’t fire? Ensure the cron daemon is installed/running (see DuckDNS “linux cron” section), or just use the systemd timer above. 

• Behind CGNAT? DuckDNS still updates, but inbound ports from the internet won’t reach your Pi; use a VPN (e.g., WireGuard) or a reverse tunnel instead.