Paessler Netflow Tester

As someone who has to deal with bandwidth monitoring configurations based on Cisco's NetFlow protocol, I found this NetFlow Testers software to be a lifesaver. It is a small program that does one thing exceptionally well; it simply dumps the data of all NetFlow packets that a computer receives from a Cisco router.

To get started, you'll first need to enable and configure the NetFlow protocol on your router. Once this is done, you must give the router the IP address of the computer running NetFlow tester so that the UDP data packets with NetFlow data are sent to this computer.

The steps to use the Paessler Netflow Tester are easy to follow. First, download the appropriate version for your testing needs; Netflow5Tester.exe for testing NetFlow version 5, and Netflow9Tester.exe for testing NetFlow version 9. Then, enter the IP and port number that you have configured as NetFlow packet target in your Cisco Router. Usually selecting "Any IP" should work, in some cases, the IP must be explicitly selected.

After completing these steps, click on "Start." You'll now see a line in the logfile for each packet the computer receives. Each line shows the time, NetFlow version, number of flows, and the IP of a packet. Note that you need NetFlow v5 for PRTG Traffic Grapher; PRTG Network Monitor supports both NetFlow v5 and v9.

For users of NetFlow5Tester, you can enable "Show Flow Data instead of packet data" to see the corresponding flow data. If you do not see any activity, then the system is not receiving any NetFlow data. This could be due to misconfiguration of the router or a firewall blocking the packets, among other reasons.

Overall, I found the NetFlow Testers software to be a great diagnostic tool for those dealing with bandwidth monitoring configurations based on Cisco's NetFlow protocol. Its ease of use and specific focus make it an essential tool for any network administrator.