You can limit access, sure: with ACLs, putting content behind login, certificate based mechanisms, and at the end of the day -a power cord-.
But really, controlling which automated retrieval tools are allowed has always been more of a code of honor than a technical control. And that trust you mention has always been broken. For as long as I can remember anyway. Remember LexiBot and AltaVista?
But really, controlling which automated retrieval tools are allowed has always been more of a code of honor than a technical control. And that trust you mention has always been broken. For as long as I can remember anyway. Remember LexiBot and AltaVista?