nProbe is a stand-alone program to listen on a network interface and
generate NetFlow packets based on the traffic it sees. You will still
need a collector (such as ntop for flow-tools) to collect the NetFlow
packets and store or process them.

nProbe is licensed under the GPL, but is not currently available for
public download. (You will need to know the appropriate username and
password to download the distribution file for this package.) Please see
the "nProbe Availability" section of <http://www.ntop.org/nProbe.html>
for more information.

A binary i386 package of the demonstration version of nProbe (limited to
exporting 1000 flows) is available here:

    http://luca.ntop.org/demo/nProbe/1.3.1/nprobe-1.3.1-netbsd-i386.tgz