I am asking how your school's security is preventing teachers, or in this case, you, from standing at the doorway when students are passing? Perhaps you could inspire others to follow your lead, benefitting everyone. Maybe you would hear something in passing that would benefit others or even yourself. You posted that you were hoping to avoid hostile students. When presented with a way to make even the smallest difference, you brought up security at your school, which doesn't make sense to me, and although it would be wonderful if all teachers chose this course of action to be proactive instead of reactive, the only person you can absolutely motivate to make a small change is yourself. How does your school's security prevent you from making this one positive change? I am simply trying to follow your logic.