What is the sign of a snake crawling under the door of the house?

The first thing to emphasize is that we can't predict the future or interpret unknown events according to divination or superstition.

From a scientific and practical point of view, snakes are reptiles. They usually look for food, habitat or suitable temperature and humidity by instinct. If snakes appear under the front door, it may be because they think the climate is suitable, the habitat is safe or the food source is sufficient.

Therefore, the appearance of a snake under the front door of a house does not necessarily represent a sign or indicate that something will happen. The best way is to keep calm, don't disturb or hurt them, and let them leave naturally. If snakes or other wild animals need to be removed, it is best to consult professional animal protection organizations or local wildlife management departments.