I might have to use a monthly capped internet. So before I do that I want to find out the average amount of data I download and upload over the internet in any given day, such that the software starts recording when the OS boots up till the point it's shutdown. This way I will have an idea of need of my usage needs per-day and then from there on calculate for a month.
It would be nice if it does the monthly forecasts too but that's not a rigid requirement.
What software should I use to achieve the above on a Linux (Ubuntu 13.10)?