Free Netflow Analyzer software

For today, I put together a list with the software that I’m using when I’m testing network behavior in the lab. The software below is free, with some restrictions but is perfect to use it when you need a quick solution to monitor your network with Netflow, sFlow or jFlow.

All the proposed software have commercial version, so if you like then and you consider one for your company please get in touch with the company that develop them for more information about licenses.


Free, graphical network monitoring tool. sFlowTrend makes use of the popular sFlow standard to generate real-time displays of the top users and applications making use of network bandwidth.

Some features:

  • Quickly understand who is using the network and what they are doing.
  • Enforce corporate acceptable network use policies.
  • Rapidly identify the cause of any problems or abnormal traffic.
  • Understand trends in usage and accurately target upgrades.
  • Generate management reports on current and historical performance.

sFlowTrend is written in Java and will run on most platforms.

Download sFlowTrend.

Solarwinds Netflow Analyzer

Solarwinds Real-Time NetFlow Analyzer captures and analyzes NetFlow data in real time to show you exactly what types of traffic are on your network, where that traffic is coming from, and where it is going. It displays inbound and outbound traffic separately for granular analysis that makes problem diagnosis quick and easy. You can view the historical NetFlow data broken out by application, conversation, domain, endpoint, and protocol. That way you know exactly how your bandwidth is being used and by whom.

  • Investigate, troubleshoot, and quickly remediate network slowdowns
  • Easily identify which users, devices, and applications are consuming the most bandwidth
  • Isolate inbound and outbound traffic by conversation, application, domain, endpoint, and protocol
  • Personalize NetFlow data displays to view traffic by specified time periods (up to 60 minutes) and by traffic type
  • Customize refresh rates and display units for NetFlow traffic

Drawback for this free version is that it can record only up to 60 minutes, than you have to restart software to record again.

Available only for Windows platforms.

Download Solarwinds Netflow Analyzer

ManageEngine Netflow Analyzer

ManageEngine NetFlow Analyzer is a, web based (no hardware probes), bandwidth monitoring, network forensics and network traffic analysis tool that has been optimizing thousands of networks across varied industries for peak performance and helping them to put their bandwidth for a better use. NetFlow Analyzer is a NetFlow, sFlow, JFLow (and more) collector, analyzer and reporting engine integrated together.


  • Real-time visibility into top applications and talkers in the network.
  • Detection of unauthorized WAN traffic.
  • Identify virus, worms and DoS attacks in real-time.
  • Understand the history of security violations with alert reports.
  • Recognize applications that use dynamic ports by performing a deep-packet inspection using Cisco NBAR.
  • Real time reports with 1 minute granularity.
  • Aggregated data stored for ever for historic reports
  • Ability to view reports in different granularity – 10 min, hourly, daily, weekly, monthly, and custom time period.

The bad aspect is that you can use it only for 30 days. Then you have to buy it. There is a trick, that if you reinstall the product you can use it again for 30 days. I advice to use this trick just for personal use or for testing purpose.

Available for Linux and Windows.

Download ManageEngine Netflow Analyzer

Plixer Scrutinizer

Plixer Scrutinizer captures Cisco NetFlow, sFlow and other flow technologies and uses that data to monitor the overall network health. Reports on which hosts, applications, protocols that are consuming network bandwidth.

Custom NetFlow Reports allow you to filter (include/exclude) in on exactly the information you need. They can be saved and run again later.


  • Adds several additional traffic analysis Report Types (e.g. Flows, Flow Volume, NBAR Support, etc.).
  • Report on Top Applications, Conversations, Flows, Protocols, Domains, Countries, Subnets, etc., across dozens of routers and switches.
  • Any saved report in Scrutinizer can be configured with a threshold to trigger an alarm.
  • DNS resolution becomes automated and a constant process.
  • Network traffic reporting and alarming on the internal network: SYN, NULL, FIN, XMAS Scans, RST/ACK worms, P2P, ICMP Unreachable, illegal IP addresses, excessive Multicast traffic, known compromised Internet hosts and more.

The bad part is that it drops the database after 24 hours. Still you can save the databases before this are dropped by the free version of Scrutinizer.

Available for Windows platforms.

Download Plixer Scrutinizer

Do you have any other alternatives that can help network engineer test their environment? Feel free to suggest in the comments form and if they are good I will add them to  this post.

How to analyze Cisco NetFlow with FREE tool

NetFlow is a network protocol developed by Cisco Systems to run on Cisco IOS-enabled equipment for collecting IP traffic information. It’s proprietary and supported by platforms other than IOS, such as Juniper routers or FreeBSD and OpenBSD. Cisco routers that have the Netflow feature enabled generate netflow records; these are exported from the router in User Datagram Protocol (UDP) or Stream Control Transmission Protocol (SCTP) packets and collected using a netflow collector. Other vendors provide similar features for their routers but with different names Jflow or cflowd from Juniper Networks, NetStream from Huawei Technology or Cflowd from Alcatel-Lucent. Since my knowledge is mainly in Cisco’s devices area, I will focus on Netflow. A NetFlow record can contain a wide variety of information about the traffic in a given flow, like Version number, Sequence number, Input and output interface indices, Number of bytes and packets observed in the flow, Source & destination IP addresses, Source and destination port numbers, IP protocol, ToS and other… By analyzing flow data, a picture of traffic flow and traffic volume in a network can be built. Cisco Netflow have multiple version from which v5 is the most used at the moment being.

After this brief explanation of what is Netflow, let’s focus on the topic of this article. Lately I was searching for a tool that can analyze NetFlow flow and return to me an acceptable picture of what’s going on in the network. There are a lot in the market and I tried many of them, which offers free trials (maybe someday I will write some reviews about them), but for now I was really searching for something without any cost involving as it was for my private use.

The NetFlow analyzer software that I was looking for, should  be able to:
1. Display graphical format of traffic (graphs, picture…)
2. Allow me to analyze as many devices / interfaces I want
3. Allow to export some reports based on the network activity collected
4. …and the most important for me, to be FREE

As I said before, I tried some tools, with great capabilities (e.g. NetFlow Analyzer from ManageEngine) but they were having limitations that disturbed me (e.g. limitation to only 2 interfaces on the tool from ManageEngine).  Searching, I arrived to Scrutinizer NetFlow Analyzer produced by Plixer International. This tool offers exactly what I was searching for, and it is free. Now the ugly part (there is always a part like this…) is that the tool is keeping all information for 24 hours. The good part is that you can export logs on a daily basis (24 hours). E.g I had to monitor traffic for some device for 72 hours, so daily I have exported the logs and the end of the monitoring period I compared all the data. Well, it’s not so nice this limitation of 24 hours. I would prefer 48 or 72 hours, because usually this is the minimum time for monitoring a connection, device or interface. If you buy a license all this limitations are removed. As I said from begining I was searching something for private use…so, this tool was perfect for me. Anyway I believe big companies can afford to buy this tool if they test it and see that fit with their needs.

Anyway, skipping over this 24 hours limitation, the tool give you the ability to gather information from as much devices / interfaces as you want. The reports are presented in nice graphical format, with lots of details. You can download Scrutinizer NetFlow Analyzer from their site, by clicking here. On the download page, you will have the possibility to download the free version (with 24 hours limitation) or the trial version which will give you all features for a certain limited period of time. For the trial version you have to complete a form and they will issue you a trial license.

For an example how to do a basic netflow configuration on a Cisco router and how to operate Scrutinizer Netflow Analyzer please see the presentation below. For the test environment I used an old Cisco 2600 router and my notebook with Scrutinizer Netflow Analyzer installed.

Please note before watching this presentation: is not affiliated in any way with Plixer International and ManageEngine and this is not a “pay per post” article. I just wanted to share with you something that I belive it can be useful.

scrutinizer netflow analyzer