OpenBsd

OpenBSD and wrap boards do a search.

hr> Another option is pcengines wrap with 3 ethernet ports (and two mini-pci slots) running OpenBSD with pf giving you traffic shaping, priority scheduling, firewalling, multipath routing and load balancing in one box for about US$130. http://www.openbsd.org/faq/pf/pl/BR

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EthernetPort