iftop: A Network Bandwidth Monitoring Tool for Linux

iftop is used to view the current bandwidth on a network interface. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. iftop must be run by a root user or a user who has sufficient privileges to monitor network bandwidths. – See more at: http://www.unixmen.com/iftop-a-network-bandwidth-monitoring-tool-for-linux/#sthash.j1BKguLB.dpuf