This morning, the security guard came to check the gas and knocked at the door first. My wife and I haven't got up yet. Did he open the door by himself?

Under normal circumstances, it should be illegal to enter other people's houses without the owner or user, but it does not necessarily constitute a crime.

But if there is a gas leak or other emergencies in the community, I don't think it will be illegal. But it's just a routine inspection. It shouldn't be entered.

Of course, there is another situation where the door is irrelevant. I don't think it's illegal for community security guards to enter the house from a safety point of view to exclude what happened in the house.

Based on these considerations, if you want to determine that the security guard is illegal, the most important thing is to see if his behavior has caused you any loss or damage.