To draw air audibly up the nose; to snuff; -- sometimes done as a gesture of suspicion, offense, or contempt.

To draw in with the breath through the nose; as, to sniff the air of the country.

To perceive as by sniffing; to snuff, to scent; to smell; as, to sniff danger.

Sniff formats hex packets from the tcpdump program and converts them to ASCII to make them easier to read and understand. Its features include colored console output, CSV file saving, and fully customizable output. The program directly accepts all tcpdump options, including parsing from packet files.

To eavesdrop on computer networks—frequently used as part of automated programs to sift information, such as clear-text passwords, off the wire.

To intercept data between a sender and receiver without interrupting the transmission.

The act of sniffing; perception by sniffing; that which is taken by sniffing; as, a sniff of air.