Sniffing

A sniffer is a program and/or device that monitors all information passing through a computer network. It sniffs the data passing through the network off the wire and determines where the data is going, where it’s coming from, and what it is. In addition to these basic functions, sniffers might have extra features that enable them to filter a certain type of data, capture passwords, and more. Some sniffers (for example, the FBI’s controversial mass-monitoring tool Carnivore) can even rebuild files sent across a network, such as an email or Web page.

A sniffer is one of the most important information gathering tools in a hacker’s arsenal. The sniffer gives the hacker a complete picture (network topology, IP addresses) of the data sent ...

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