Binary package “iftop-dbg” in ubuntu precise

displays bandwidth usage information on an network interface (debug)

 iftop does for network usage what top(1) does for CPU usage. It listens to
 network traffic on a named interface and displays a table of current bandwidth
 usage by pairs of hosts. Handy for answering the question "Why is my Internet
 link so slow?".
 .
 This package contains the debugging symbols.