Sniffers - Basics and Detection

A Sniffer is a program or a device that eavesdrops on the network traffic by grabbing information travelling over a network. Sniffers basically are "Data Interception" technology. They work because the Ethernet was built around a principle of sharing. Most networks use broadcast technology wherein messages for one computer can be read by another computer on that network.

In practice, all the other computers except the one for which the message is meant, will ignore that message. However, computers can be made to accept messages even if they are not meant for them. This is done by means of a Sniffer!