Free Graphical Netflow Analyzer for FreeBSD / Windows

[World of Open Source]

Dear all,

I would like to know seek any advices from all people here about any free
tools for analyzing netflow data which can generate nice management report
(chart, graph) like SolarWinds/any commercial products, that can be run
either or Windows or FreeBSD (prefer).

Right now, I'm exploring /usr/ports/net-mgmt  , but find too many choices.

Your kind advices are really appreciated.

-woss-