diff --git a/duidreader.exe b/duidreader.exe
new file mode 100644
index 0000000..94d66a0
Binary files /dev/null and b/duidreader.exe differ
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..a01f7af
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module git.send.nrw/sendnrw/duidreader
+
+go 1.23.1
+
+require golang.org/x/sys v0.33.0
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..9e6ab4c
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
+golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..8b70ff3
--- /dev/null
+++ b/main.go
@@ -0,0 +1,129 @@
+package main
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+// ---------- Linux ----------
+
+func duidsLinux() (map[string][]byte, error) {
+	candidates := []string{
+		"/var/lib/NetworkManager",
+		"/var/lib/dhcp",
+		"/var/lib/systemd/network",
+		"/run/systemd/netif/leases",
+	}
+	out := map[string][]byte{}
+
+	for _, dir := range candidates {
+		_ = filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
+			if err != nil || d.IsDir() {
+				return nil
+			}
+
+			// lease/duid files are small, read entire file
+			buf, err := os.ReadFile(path)
+			if err != nil {
+				return nil
+			}
+
+			duid := extractDUID(buf)
+			if len(duid) > 0 {
+				out[path] = duid
+			}
+			return nil
+		})
+	}
+	if len(out) == 0 {
+		return nil, errors.New("keine DUID-Datei gefunden")
+	}
+	return out, nil
+}
+
+// very tolerant parser: tries common patterns
+func extractDUID(b []byte) []byte {
+	// Pattern „default-duid "\x00\x03\x00\x01\xaa…"“
+	if bytes.Contains(b, []byte("default-duid")) || bytes.Contains(b, []byte("dhclient.duid")) {
+		start := bytes.IndexByte(b, '"')
+		end := bytes.LastIndexByte(b, '"')
+		if start >= 0 && end > start {
+			hexEsc := b[start+1 : end]
+			hexEsc = bytes.ReplaceAll(hexEsc, []byte(`\x`), nil)
+			duid, _ := hex.DecodeString(string(hexEsc))
+			return duid
+		}
+	}
+	// systemd-networkd file: plain hex without 0x
+	if allHex(b) {
+		duid, _ := hex.DecodeString(strings.TrimSpace(string(b)))
+		return duid
+	}
+	return nil
+}
+
+func allHex(b []byte) bool {
+	for _, c := range bytes.TrimSpace(b) {
+		if !strings.ContainsRune("0123456789abcdefABCDEF", rune(c)) {
+			return false
+		}
+	}
+	return true
+}
+
+// ---------- Windows ----------
+
+func duidsWindows() (map[string][]byte, error) {
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE,
+		`SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters`,
+		registry.READ)
+	if err != nil {
+		return nil, err
+	}
+	defer k.Close()
+
+	val, _, err := k.GetBinaryValue("Dhcpv6DUID")
+	if err != nil {
+		return nil, err
+	}
+	return map[string][]byte{"registry": val}, nil
+}
+
+// ---------- macOS (scutil) ----------
+// (Beispielskizze – nicht implementiert)
+// func duidsDarwin() ...
+
+// ---------- main ----------
+
+func main() {
+	var duids map[string][]byte
+	var err error
+
+	switch runtime.GOOS {
+	case "windows":
+		duids, err = duidsWindows()
+	default: // linux, darwin, ...
+		duids, err = duidsLinux()
+	}
+
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "Fehler:", err)
+		os.Exit(1)
+	}
+
+	hostName, _ := os.Hostname()
+
+	for _, d := range duids {
+		fmt.Printf("%s", hex.EncodeToString(d))
+		fmt.Printf("%s", hostName)
+	}
+}