QoF (Quality of Flow) is an IPFIX Metering and Exporting process derived from the YAF flowmeter, designed for passive measurement of per-flow performance characteristics.
QoF is primarily intended to support research into passive measurement of performance metrics for TCP flows; however, it can also be used for general flow measurement, especially in environments where the deployment of technologies which inspect packet payload is restricted. If what you're looking for is a full-featured flow meter for security applications, stop reading now and go download the latest version of YAF from http://tools.netsa.cert.org/yaf instead.
Changes from YAF
QoF is a fork of YAF version 2.3.2, with the following major differences from the YAF codebase:
Removal of all payload inspection code.
Replacement of packet acquisition layer with WAND's libtrace.
Replacement of most command line flags with a YAML-based configuration file, which allows implicit feature selection through direct specification of the information elements to appear in QoF's export templates.
Support for new information elements focused on passive TCP performance measurement.
QoF is licensed under the GNU General Public License, Version 2.
Run without arguments, QoF will read packets from standard input and produce IPFIX on standard output using a minimal biflow template. For more detailed usage instructions, see the man page installed with QoF, or http://britram.github.io/qof/qof.pdf.