I'm looking for a permanently-running monitor which can emit a monthly (or daily, etc) bandwidth report, in a per-program manner. Example desired output:
Bandwidth consumption: last 30 days ============== Program Downloaded Uploaded /usr/bin/ssh 30MB 100MB /usr/bin/java 9000MB 3000MB
(it also could be per-process instead of per-program, but then I'd have to consolidate entries manually)
After significative research (including many similar questions over Stack Exchange), I still haven't found such a monitor. Maybe this is not possible under Linux. Or maybe this is bit of an unusual need.