vnstat: vnstat - console-based network traffic monitor
vnstat: 
vnstat: vnStat is a console-based network traffic monitor for Linux and BSD
vnstat: that keeps a log of network traffic for the selected interface(s). It
vnstat: uses the network interface statistics provided by the kernel as
vnstat: information source. This means that vnStat won't actually be sniffing
vnstat: any traffic and also ensures light use of system resources.
vnstat: 
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