Shows process using CPU and memory
Shows process doing IO, "-o" shows only the process actually doing IO instead of all processes.
Shows network activities by address / port etc. but no process showed
the only tool (said) to monitor network traffic by process
if vpn enabled, be sure to choose the correct tunnel interface, or nothing is monitored
Command tools to monitor linux performance
http://www.tecmint.com/command-line-tools-to-monitor-linux-performance/
top - original tool
htop - adds support to multicore/cpu
iotop - input/output monitoring
iftop - network monitoring
atop - merges previous elements into a single overview
slabtop – displays a listing of the top caches