1. Log into your QNAP by SSH. It is possible by e.g. PuTTy, it is a free program which you can download here.
2. In Host Name (or IP address) field enter QNAP IP address, choose connection type SSH. After these steps click Openor, if necessary, change other settings.
3. When the above window appears, select Yes.
4. Enter the login and password to your QNAP.