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Joe Loiacono



Powered by flow-tools and SiLK
Advancing Network Traffic Situational Awareness

FlowViewer provides a dynamic web front-end to two powerful open-source netflow data collector and analyzers, Mark Fullmer’s flow-tools suite and the Carnegie Mellon NetSA group’s netflow data capture/analyzer, SiLK. The inclusion of the underlying SiLK tool set enables existing FlowViewer users to continue to use the tool with the newer IPFIX netflow data protocol.

FlowViewer has been developed for NASA’s Earth Sciences Data and Information System (ESDIS) networks, and credit goes to NASA for their usual outstanding support of innovation.

FlowViewer Main page

FlowViewer provides users with the ability to quickly extract network management information of interest from voluminous quantities of stored netflow data. The user can configure a [Dashboard] of continuously updating FlowTrackings to maintain a situational awareness of his organization's network traffic. FlowViewer consists of three primary tools: FlowViewer, FlowGrapher and FlowTracker. The user is able to filter data (inclusion or exclusion) by device, IP address range, port, router interface, autonomous system (AS), specified time interval, protocols, TOS field, TCP flags, exporter, and next-hop. All generated reports and filters can be saved for future application. The user can switch between the tools preserving the previously specified filter. FlowViewer makes flow data analysis and tracking quick and easy.

[FlowViewer] enables the user to create text based reports from filtered netflow data. Several different reporting formats are provided. Each of these reports can be sorted by column heading.

[FlowGrapher] enables the user to graph the bandwidth used by a filtered subset of netflow data during a specified time period. Resulting reports include the graph and a textual listing of the largest flows.

[FlowTracker] enables the user to maintain a long-term history of a particular traffic subset. FlowTrackings consist of five graphs of traffic over suceesive longer time periods: Daily, Weekly, Monthly, Yearly, and Last 3 Years.

The user must install and configure either flow-tools, or SiLK. Users already running FlowViewer with flow-tools may opt to install SiLK in parallel to handle IPFIX exporters while leaving older exporters in place. The ability to collect and analyze IPFIX data requires SiLK (download SiLK) now at version 3.7.1. FlowViewer v4.0 continues to work with flow-tools for pre-IPFIX versions of netflow.

The FlowViewer graphing and tracking capabilities make use of such intrepid open source software as Thomas Boutrell’s gd, Lincoln Stein's GD, Martien Verbruggen's GD::Graph, and Tobias Oetiker’s RRDtool packages.

For more information including software requirements and installation instructions, please review the FAQ, User's Guide or the README file. Or, contact me directly at For somewhat larger images, please see the Screenshots.


Wiki: Dashboard
Wiki: FlowGrapher
Wiki: FlowTracker
Wiki: FlowViewer

  • Junior

    I see the requirement for Silk V3.0. I recently got Silk v2.5 up and running. Is it a futile effort to have this version of FlowViewer work with Silk v2.5? Reduced functionality, or simply won't work? Can someone please elaborate on this, or give some idea when Silk v3.0 will be available for open release? Thank You!

    • Joe Loiacono
      Joe Loiacono

      Yes - I tried v2.5 myself, but the limitations are (as I recall) that flow start and end times were not recoverable from netflow v9 and this wreaks havoc on FlowGrapher and FlowTracker. I can't recall whether the FlowViewer tool worked. I didn't try v2.5 on netflow v5 - probably because flow-tools works just fine there - but you might try it as it will be good prep for moving to v3.5 whenever.

      Here's the (unfortunate) latest on SiLK:

      "Due to changes in the oversight of the SEI that are outside of our control, major new releases of NetSA software are required to go through release review by the Office of the Secretary of Defense (OSD) before the software may be given to anyone who is not a federal government employee. Unfortunately, new releases of SiLK have been stuck in this process for a long time, and currently there is no estimate as to when this review will be completed."

      • Junior

        Thanks for your timely reply. That's what I was afraid of.

        I'm just starting to gather some experience with handling netflow data. My ASA firewall seems to be limited to Netflow v9 so I fell into Silk to handle that detail, saw the connection to Flowviewer and was hoping to implement, learn, and have that capability. I suppose there is still lots to learn, and useful data to be had, with Silk 2.5 though.

        Ultimately, I'm pretty agnostic on what tool to use, mostly have been looking for open source (free) tools and chasing various ideas. Have tried nfdump & nfsen a bit. Mostly just collecting data at this point. Always looking for ideas.

        No need to support IPv6.

        Last edit: Junior 2013-06-13
    • Joe Loiacono
      Joe Loiacono

      But wait! No sooner do we bemoan the delay of the general public release of SiLK and presto: it's available (as of June 20, 2013)!

      Download here: SiLK