Support for RFC 6313 Flow (Cisco VZFLOW)

[i3149]

RFC 6313 (https://www.rfc-editor.org/rfc/rfc6313.html) defines an extension to IPFIX which includes more complex data structures like lists.

Cisco seems to be using this for their nvzFlow product -- https://blogs.cisco.com/security/an-introduction-to-the-new-cisco-network-visibility-flow-protocol-nvzflow.

Right now, when VZFLOW is sent to Goflow it results in errors like:

2022-08-31T22:15:17.823 ktranslate/netflow9 [Error] flow Error from: NetFlow (0) duration: 40.168µs. NetFlow/IPFIX version error: 25701

I also found an elasitflow bug on this but I'm not sure of the fix -- robcowart/elastiflow#343.

[lspgn]

Found a collector which outputs RFC6313: https://tools.netsa.cert.org/yaf/deeppacketinspection.html#dpi-data-export