how to stop squirrels from entering house

http://sainskini.com/news/baltimore-wildlife-control-company-warns-residents-about-raccoons-and-squirrels-invading-homes-during-fall-season/0188091/

Rats can be eliminated by suitably baited springtime traps and can be caught in cage traps for moving. Baby powder or "tracking powder" can be used to develop courses used by rats inside structures and acoustic