Describe the capabilities of a sniffer.

What will be an ideal response?

A sniffer is a program or device that can monitor data traveling over a network. Sniffers can be used both for legitimate network management functions and for stealing information from a network. Unauthorized sniffers can be extremely dangerous to a network's security because they are virtually impossible to detect and can be inserted almost anywhere. This makes them a favorite weapon in the hacker's arsenal. Sniffers often work on TCP/IP networks, where they're sometimes called packet sniffers. Sniffers add risk to the network because many systems and users send information on local networks in clear text. A sniffer program shows all the data going by, including passwords, the data inside files, and screens full of sensitive data from applications.