@jacotec I know this is an old thread, but I don’t think Softflowd can quite deliver what you are asking. If you want a report of one 30 min flow in NtopNG, you have to ask softflowD not to expire flows on a timer - you need to leave the expiration field empty. (Otherwise it effectively reports flows that is not completed as unique flows).
Then you get what you want, but the problem is then that you cannot see the flow while it is in progress. You have to wait 30 min.
What we really need is a Nprobe package for pfSense that allows us to install Nprobe (and license it). That way it can do the actual capture/analyze part - including the much more insightfull DPI features compared to standard netflow, and report all of it to NtopNG on another machine via ZMQ.