This article may shed some light?
Where Carnivore Lives
For Carnivore to gain access to this much data, its hardware must be plugged directly into the network at a central location. Because most Internet-based communications in the USA flow through large Internet Service Providers (ISPs), the FBI would typically install a Carnivore box inside an ISP data center. Controlled physical and network access improves the system's overall security.
The FBI has already employed Carnivore in a number of cases. By law, the details of these investigations have generally not been released publicly. The only ISP positively identified as cooperating with such an investigation, in fact, is Earthlink. In that case, the deployment of Carnivore at a data center in Pasadena, CA caused some service disruptions to otherwise uninvolved customers [source: CNet]. This fact alone alarms some Net users.
Reactions To Carnivore
"This is a matter of employing new technology to lawfully obtain important information while providing enhanced privacy protection." - FBI
Network sniffers are not new tools. For years it has been common practice, for example, to snoop on email traffic flowing over some corporate networks [5]. A system that scans mail ports can easily be expanded relatively easily to monitor file transfers, Internet chat sessions, and various other forms of network traffic. Carnivore's functionality is configurable, too, but the use of the system is governed by federal wiretap laws. Some of the negative reaction to Carnivore is due no doubt to the FBI's prior (unsuccessful) efforts to modify standard network protocols to better facilitate wiretapping [6].
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