A Dedicated firewall device is positioned between the internal, trusted network (Green Interface) and the Untrusted External Interface (Red Interface) to prevent unauthorized network traffic from entering the network.

The Orange Interface provides accessibility for public access servers such as web, email or other data on a separate network. The Blue Interface is for public access to wireless access points on a separate network and is unable to access any data on the Green Interface.

Any connection to the Internet should contain a dedicated firewall device. Cable Modem, DSL, ISDN and T connections are especially important to protect due to their always connected status.

It is important to note that devices on the Orange interface do not normally have direct access to devices and data on the Green interface without opening specific ports to allow data passthrough.