Open vSwitch is a production quality, multilayer virtual switch licensed under the open source Apache 2.0 license. It is designed to enable massive network automation through programmatic extension, while still supporting standard management interfaces and protocols (e.g. NetFlow, sFlow, IPFIX, RSPAN, CLI, LACP, 802.1ag). In addition, it is designed to support distribution across multiple physical servers similar to VMware's vNetwork distributed vswitch or Cisco's Nexus 1000V.

IP accounting iconoclasm.

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 and correlate RPKI data; 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).

pmacct @ GitHub

Flow collector, enricher and visualizer.
This program receives flows (currently Netflow/IPFIX and sFlow), enrice them with interface names (using SNMP), geo information (using MaxMind), and exports them to Kafka, then ClickHouse. It also exposes a web interface to browse the collected data.