iftop: iftop (Display bandwidth usage on an interface)
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iftop: iftop does for network usage what top(1) does for CPU usage.  It 
iftop: listens to network traffic on a named interface and displays a table
iftop: of current bandwidth usage by pairs of hosts. Handy for answering 
iftop: the question "why is our ADSL link so slow?"
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