Use \r\n as line ending

RFC 1413 explicitly requires \r\n as line ending (EOL).

main.go

@@ -144,7 +144,7 @@ func handleIdentRequest(c net.Conn, hmacSecret []byte) error {
 	fmt.Fprintln(mac, uid)
 	macHex := hex.EncodeToString(mac.Sum(nil))
 
-	_, err = fmt.Fprintf(c, "%d,%d:USERID:OTHER:%s\n",
+	_, err = fmt.Fprintf(c, "%d,%d:USERID:OTHER:%s\r\n",
 		lPort, rPort, macHex[:MacBytes])
 	if err != nil {
 		return err