As networks continue to grow, sometimes against our wishes, sometimes with our full support, it becomes more important to get some overview of how and what is moving across your network(s.)
In the beginning, in a land far away, we only had a few machines wired up and life was simple.
Now, most of us have too many machines with an unknown quantity of malware pounding on them (and subsequently on your network.) That's before we even get to our beloved users.
If you get blamed when things go bad on your network, it's time you started taking charge of knowing what's going across your network. Michael W. Lucas' published an insightful book to help us with that Network Flow Analysis. More importantly, for us, is that he chose to describe the solution using tools accessible to everyone (aka Open Source.) We've finally cleaned up some internal notes for getting the software to work well in our favourite os (tm) OpenBSD
These notes augment the installation instructions from that book. Where the human factor is important, in customisation/localisation, interpretation, we don't do any of that here.
Now you're back, follow through to find out how we put it together for Netflow with flow-tools
It's saved our bacon a number of times, we know who's packets are causing congestion, what times congestions occur, why things occur. AND, we can print out those meaningless charts that senior dweebs nod their heads and just love.
Michael W. Lucas has some war stories where traffic flow monitoring has helped him out, and we can attest to it's daily, weekly value.
Our notes on Netflow with flow-tools