Getting the network traffic amount since the interface went up

[Parv]

I am interested to know the total amount of data passed through a
network interface (em0 in my case) since the interface went up.  So
far, i have seen that pload, nload, & "netstat -b -I" report the
amount since the operating system has been up, not since the new
ethernet connection has been (re)established.

Is there a way to find out the amount of traffic (in & out) since a
network interface has been up (not since the OS has been up)?

  - Parv

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