pmacct is a small set of multi-purpose passive network monitoring tools. It can account, classify, aggregate, replicate and export forwarding-plane data, ie. IPv4 and IPv6 traffic; collect and correlate control-plane data via BGP and BMP; collect infrastructure data via Streaming Telemetry. Each component works both as a standalone daemon and as a thread of execution for correlation purposes (ie. enrich NetFlow with BGP data).
Find out more about pmacct here or checkout a more comprehensive list of tools over at LinkedIn here.