I'm looking for a way to log how much data transfer a server is using, preferably I would just see data transfer for outside of my local network, but even all traffic would be alright. Mainly I want to see how much traffic is coming from my ftp server. (using pure-ftpd) Is there any easy way to set this up? I'm hoping for daily/weekly/monthy traffic kind of deal. It should be a CLI app that can run in the background. Any reccommendations?