[clug] IPTables question

[Michael Cohen]

Hi list,
  I am trying to add logging to my iptables firewall. I can use the LOG action
  when placed in front of any rule which will log a message whenever a packet
  (or established session) matches that rule in that chain. However I want to
  be able to tell the length of connections and the amount of traffic exchanged
  per connection as per netflow for example.

  Is it even possible to do with iptables or do I have to resort to some other
  tool? Which tool is preferable in that case?

Thanks,
  Michael