Sniffing Sniffing is one of the most popular forms of attacks used by hackers. Computer networks are shared communication channels - this means that computers can receive information that was intended for other terminals. To capture such information travelling over a network is called sniffing. An example: On an Ethernet network, packet information is sent to all the hosts on the same circuit. However, since the packet header contains the address of the destination device, only the computer with the matching address is supposed to accept the packet when it passes by. A device that accepts all packets no matter what the packet header says, such as a router or firewall, is said to be in promiscuous mode. Such a device can be used for sniffing. Sniffing can be used to obtain username and password information for the computers on a local network when the information is transmitted in non-encrypted form.
