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+# 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](https://nssm.cc/)).
+
+# 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](https://nssm.cc/)) 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`)
+```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
+```bash
+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)
+```PowerShell
+.\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](https://nssm.cc/) 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`
+```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`
+```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)
+```log
+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
+```