Greg Hetson was granted the protection from Alia Hetson ... after filing docs saying Alia banged on his front door earlier this month around 3 AM, and yelled for him to come talk to her. She left, but returned an hour later to knock on his bedroom window.

In the docs, obtained by TMZ, Greg says he completely crushed any hope of them getting back together at the end of November, and insists she's been stalking and harassing him ever since. He also suspects she broke into his place through a doggy door.

The exes have gone back and forth with restraining orders and police visits for years.

For now, she has to stay 100 yards away from Greg.