It's built into FreeBSD: https://www.freebsd.org/cgi/man.cgi?query=netmap&sektio...

kev009 on June 16, 2015 | parent | context | favorite | on: How to receive a million packets per second

It's built into FreeBSD: https://www.freebsd.org/cgi/man.cgi?query=netmap&sektion=4

Netmap is commonly used in HFT as well as packet filtering applications. I believe Verisign is running some of the root DNS servers with netmap as well, getting millions of connections per second.