Unlike telephone circuits, computer networks are shared communication channels.
Sharing means that computers can receive information that was intended for other machines.
The easiest and most obvious way to manage risk on networks is to remove any sensitive information from computers connected to the network. However, this may not always be possible. Boston College LANs are not directly accessible from the Internet. BC has a one-way connection to the Internet, in that information can leave BC, but outsiders cannot access BC except for a few machines designed for public access. Not all threats will be present in your environment.