Apparently there are quite a few YAF IPFIX deployments out there. We recently had to test this software for a customer.  YAF stands for Yet Another Flowmeter which promotes the use of SiLK for some rudimentary threat detection.  Flow Analytics(TM)  can be used for more sophisticated network threat detection.  YAF can be placed off a spanned switched port and used as a NetFlow probe to improve network traffic monitoring; however, the metrics collected are not nearly as sophisticated as the nBox.

The configuration of YAF is pretty straight forward.
sudo yaf –in eth0 –live pcap –out –ipfix udp –ipfix-port=2002 –stats=300 –mac –idle-timeout=60 –active-timeout=60 –udp-temp-timeout=300 –force-read-all –silk –observation-domain=42 –flow-stats –delta –ingress=1 –egress=1 –max-payload=128 –export-payload –udp-payload –entropy –applabel –p0fprint –fpexport

Some options above are optional, others are not.  For instance, using “–silk” is very important due to how that effects the export.
Descriptions of each option are available on the YAF web site.  An interesting piece of information is that like many security appliances (e.g. SonicWALL, Cisco ASA) that support IPFIX, YAF supports bidirectional NetFlow this was evident when we saw things like octetDeltaCount and octetDeltaCount_rev (rev =  reverse) in the same template. Other unique elements included:

  • droppedPacketTotalCount
  • exportedFlowRecordTotalCount
  • exportingProcessId
  • flowAttributes
  • flowEndReason
  • ignoredPacketTotalCount
  • initialTCPFlags
  • octetTotalCount_rev  which may support RFC 5610, I need to look at it a bit more with our developers
  • silkAppLabel
  • tcpSequenceNumber
  • unionTCPFlags

All of which can be reported on using our Report Designer.  The report designer allows customers to select any template from any device, select the elements and of course, group, orderby, sum, count, average, etc. on any column for trending.  Consider it a sort of Crystal Reports for flow templates.  Anyway, a YAF reporting example can be seen below.

yaf netflow support

As you can see above, our configuration caused an export of 12 templates!  There is nothing wrong with this and the reason for it is the topic of perhaps another blog.  For now, understand that it demonstrates how the IPFIX industry is evolving.


Thomas Pore is the Director of IT and Field Engineering at Plixer. He developed and leads, the Malware Incident Response and Advanced NetFlow Training programs which are being offered in cities across the USA. He is also an adjunct professor at the local community college and teaches ethical hacking. Thomas travels the globe meeting with customers and trying improve the Scrutinizer network incident response system. He helps clients optimize threat detection strategies and aids in the configuration of custom incident response solutions. He has a Bachelor of Science in Computer Science from Dickinson College.


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