softflowd is a NetFlow collector that can be deployed on pfSense software.
Installing softflowd
There is a package available under System > Packages on the Available Packages tab. Find it in the list, click at the end of its row, and confirm the installation.
Configuring and Launching softflowd
Softflowd works similar to pfflowd.
Once the package has been installed, visit Services > softflowd to configure the service.
Interface: Ctrl-click to select all of the interfaces from which NetFlow data should be gathered
Host: The target NetFlow server which will receive flow data
Port: The port on the Host which is listening for NetFlow data
Max Flows: The number of flows to track before older flows expire
NetFlow Version: The desired version of the NetFlow protocol. See NetFlow Versions on Wikipedia for more information.
Controlling softflowd from the Command Line
To view statistics about the running softflowd process, run the following command, replacing em0 with the actual network interface to query:
: softflowctl -c /var/run/softflowd.em0.ctl statistics
To expire all flows and force an update to be sent to the netflow server, run the following command, replacing em0 with the actual network interface to control:
: softflowctl -c /var/run/softflowd.em0.ctl expire-all
Reference https://docs.netgate.com/pfsense/en/latest/monitoring/exporting-netflow-with-softflowd.html