Ipt-netflow is an iptables/netfilter target which generates traffic statistics in NetFlow v5 and v9 format as well as in IPFIX format.

It provides high performance and scalability. For highest performance module could be run without conntrack being enabled in kernel. Reported to be able to handle 10Gbit traffic with more than 1500000 pps with negligible server load (on S5500BC).