daily i've atleast 9-10 visitors in my office and out of them mostly asks for internet connectivity, so i gives them wi-fi connectivity but the problem is once they are connected to network (if someone is too talented) they can access my private network and any data on the server.
so i need to prevent these things
please help me on this
the devices at my end
Cisco 24 Port Manageable Switch
Cisco 1800 Series Router
Cisco 506e Firewall
thanks in advance