[ Thanks to linuxaria for this link.
]
“NetHogs is a small ‘net top’ tool. Instead of breaking the
traffic down per protocol or per subnet, like most tools do, it
groups bandwidth by process. NetHogs does not rely on a special
kernel module to be loaded. If there’s suddenly a lot of network
traffic, you can fire up NetHogs and immediately see which PID is
causing this. This makes it easy to indentify programs that have
gone wild and are suddenly taking up your bandwidth.”