keep somebody out(The reality is that most organizations are fighting the battle with an approach that can never win, one based almost solely on identifying the bad guys and keeping them out. vlad-and-slav)
keep well back(keep well back from something or someone – держаться на значительном расстоянии от чего-либо или кого-либо; He preferred keeping well back from their house to having any contacts with them. – Он предпочитал держаться на значительном расстоянии от их дома вместо каких-либо контактов с ними. TarasZ)
