Nethogs is a simple program that shows the send and receive rates per second organised by process.
To install, simply type on the command line
# yum install nethogs (For Fedora) # aptitude install nethog (For Linux Mint)
The default device to monitor is eth0. If you wish to use other device, simply type the argument after nethog
# nethogs eth1To cycle through the available options for displaying the data transfer such as kilobytes, megabytes and bytes, just press m
For more information, click the nethogs project website