Ipt-netflow is fast and effective Netflow exporting module for Linux kernel. Designed for Linux router with heavy network load. This is netfilter/iptables module adding support for NETFLOW target. It's not using conntrack for performance reasons.
ipt-netflow version 1.8 has been released. This is minor bug fix release with small improvements.
SourceForge.net Project Page:
http://sourceforge.net/projects/ipt-netflow/