DDNS Updater (Go)

Small, reliable DDNS updater written in Go. It periodically checks your public IP (via a configurable IP service) and calls your provider's DDNS update URL only when the IP changes. Designed to run continuously and easily be installed as a Windows service (we recommend using nssm).

Features

• Poll public IP at configurable intervals (seconds).

• Call DDNS update URL only when IP changes.

• Simple JSON config (config.json).

• Console output + optional file logging.

• Runs perfectly under a service wrapper (e.g., nssm) or Task Scheduler.

• Works with any DDNS endpoint (cPanel, DuckDNS, No-IP, etc.).

Requirements

• Go 1.20+ to build (or download prebuilt .exe).

• Windows for service operation (works anywhere Go runs if you run it directly).

• If running as a Windows service, we recommend using nssm to wrap the executable.

• Internet access to the configured IP check endpoint (default https://api.ipify.org) and your DDNS update URL.

Example config (config.json)

{
  "update_url": "https://triztech.pro/cpanelwebcall/TOKEN",
  "check_interval_seconds": 30,
  "ip_check_url": "https://api.ipify.org",
  "log_file": "ddns.log"
}

update_url — full DDNS update URL (including token).

check_interval_seconds — how often to check public IP (seconds).

ip_check_url — a simple service returning your public IP (plain text).

log_file — optional path for logfile (relative to program CWD).

Build

go build -o DDNSUpdater.exe ./path/to/ddns_updater.go

Place DDNSUpdater.exe and config.json in the same folder for easy management.

Run manually (for testing)

.\DDNSUpdater.exe
# or double-click in Explorer

It will print status lines to stdout and update the DDNS only when the IP changes.

Running as a Windows service (recommended)

Use nssm to wrap the executable — it handles start/stop correctly, captures stdout/stderr to files, and restarts on crash.

Install script (example)

Drop DDNSUpdater.exe, config.json, nssm.exe, and the script into the same folder. Run as Administrator.

install_ddns_service.bat

@echo off
SET SCRIPT_DIR=%~dp0
SET EXE=%SCRIPT_DIR%DDNSUpdater.exe
SET NSSM=%SCRIPT_DIR%nssm.exe

IF NOT EXIST "%EXE%" (
  echo DDNSUpdater.exe not found
  pause
  exit /b 1
)
IF NOT EXIST "%NSSM%" (
  echo nssm.exe not found
  pause
  exit /b 1
)

REM remove old service if exists
"%NSSM%" remove DDNSUpdaterService confirm

REM install service
"%NSSM%" install DDNSUpdaterService "%EXE%"
"%NSSM%" set DDNSUpdaterService AppDirectory "%SCRIPT_DIR%"
"%NSSM%" set DDNSUpdaterService Start SERVICE_AUTO_START

REM optional: stdout / stderr logs
"%NSSM%" set DDNSUpdaterService AppStdout "%SCRIPT_DIR%ddns_stdout.log"
"%NSSM%" set DDNSUpdaterService AppStderr "%SCRIPT_DIR%ddns_stderr.log"

"%NSSM%" start DDNSUpdaterService
echo Installed and started DDNSUpdaterService
pause

Uninstall script

uninstall_ddns_service.bat

@echo off
SET SCRIPT_DIR=%~dp0
SET NSSM=%SCRIPT_DIR%nssm.exe

IF NOT EXIST "%NSSM%" (
  echo nssm.exe not found
  pause
  exit /b 1
)

"%NSSM%" stop DDNSUpdaterService
"%NSSM%" remove DDNSUpdaterService confirm

echo DDNSUpdaterService removed
pause

Run these scripts as Administrator.

Tips & Best Practices

Use log_file to capture activity when running as a service. NSSM can also capture stdout/stderr for you.

If you run behind a reverse proxy (e.g., Caddy), keep the updater independent — it only updates DNS, it does not interact with the proxy.

Troubleshooting

No updates happening: check config.json for correct update_url and ip_check_url. Run the updater manually and inspect logs.

Service installs but stops immediately: ensure the binary runs continuously (it should sleep/poll in a loop). When running via NSSM, the process must not exit.

Permission issues installing service: run the install script as Administrator.

IP check returns unexpected data: try curl https://api.ipify.org and make sure the endpoint returns a plain IPv4/IPv6 string.

Example behavior (log lines)

2026-03-17T12:00:00Z Starting DDNSUpdater
2026-03-17T12:00:00Z Current IP: 154.241.114.93 (no previous value)
2026-03-17T12:00:00Z Updating DDNS at https://triztech.pro/cpanelwebcall/TOKEN -> OK
2026-03-17T12:00:30Z IP unchanged: 154.241.114.93