Does any body know any plugin for nfsen which can analyse protocols and
give out report for us? ( using netflow )
By default nfsen only shows TCP, UDP and ICMP traffic not detail.
For example I want to show me how much "YMessenger" traffic I have, or how
much "IMAP" traffic I have.
I think you want the PortTracker plugin. Goog for "nfsen plugins" and you'll find it.
Its a port tracker and traffic analyser, the plugin I want can gather
valuable data from netflow.
For example "GTalk" is on port 80 and this plugin can not detect it
You're not going to get that kind of detail from Netflow. It doesn't have the visibility into application layer to tell you GTalk from straight HTTP, from any other traffic that might be riding on destination socket tcp/80. You need something with visibility and intelligence higher up in the stack (sniffer, packet inspection engine, etc).