This is something like what you do in vipassana meditation. The house is your mind. The six doors are your six senses. Greeting people at the door is similar to the six senses meeting their respective stimuli. Talking to your guests at each door and not letting them in is like reflecting on the impermanence, suffering, and non-self nature of this process and letting them go. The same way you keep your house free from trouble as in the above metaphor, you can keep your mind free from suffering during meditation.
Note: This metaphor about the house was originally taken from one of Ajahn Chah's books. I have slightly modified it here.