Ipt-netflow is very 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 1.5.1 has been released. This version have improved compliance to NetFlow standard and compatibility with iptables/xtables 1.4.x. Added options to configure script for manual configuration.
SourceForge.net Project Page:
http://sourceforge.net/projects/ipt-netflow/