From tecmint.com
There are tons of open-source network monitoring tools available for the Linux operating systems on the web. Say, you can use the iftop command to monitor bandwidth usage, netstat command, or ss command to see reports on interface statistics, or top command to watch running process on your system.
But if you are really looking for something that can give you real-time statistics of your network bandwidth per process usage, then NetHogs is the only utility you should look for.