Usually, a Proxy will be configured with different protection levels, and all users on the network given logins and passwords. A Firewall is usually used for blocking computers from outside the network from connecting in, but can also be used for blocking outgoing connections as well. Now I will move on to network protocols and addressing, as well as network types. There is much confusion in these areas. First of all, a network type is how the computers are connected.
Ethernet is by far the most common network type.
There is also Token Ring, LocalTalk and Airport, just to name a few. What each network type has in common is that each provides a way for digital blocks of data to be transferred from a network card in one computer to the network card in another. This language is independent of the network type. For instance, AppleTalk network protocol can be used on Ethernet, LocalTalk, Token Ring, and Airport network types. The real difference between a network type and a network protocol is the different between hardware and software.