YAF is Yet Another Flowmeter. It processes packet data from pcap(3) dumpfiles as generated by tcpdump(1) or via live capture from an interface using pcap(3) into bidirectional flows, then exports those flows to IPFIX Collecting Processes or in an IPFIX-based file format. YAF's output can be used with the SiLK flow analysis tools and the NetSA Aggregated Flow (NAF) toolchain.