DOI link for Sniffing Traffic
Sniffing Traffic book
Ethereal is an excellent sniffer program that allows the capturing of network packets as they traverse the network to allow the user to look “inside” the packets themselves for information about the sender and/or receiver. Information that can be useful to an attacker includes the following:
Data (much data is sent in clear text; including File Transfer Protocol (FTP), Telnet, e-mails, etc.).