To hear knocking suggests we are being given permission from our spiritual self to progress on our current journey. Some believe that it is a way of alerting the psyche to the realms of spirit.
Psychological / emotional perspective: If we ourselves are knocking on a door, we may be wanting to become part of someone’s life, looking for a particular type of information asking for help or seeking different opportunities. We are waiting for permission before moving forward.
Material aspects: To hear knocking in a dream generally alerts us to the fact that our attention needs to be re-focused.
For instance, we may be too introverted when in fact we need to be paying more attention to external matters.