Update Oct 20, 2017 As pointed out in the comments below, most of this is no longer needed since the official release of the telegraf package for pfSense 2.4 and above. I'm still leaving it up for posterity. If any of the pfSense folks read this, some extra configuration options on the settings page for the plugin would be nice to see; but otherwise works like a charm. If you’re like me, a sexy looking dashboard is a difficult thing to look away from.