FreeBSD-Based m0n0wall Firewall/Network OS Announces The End Written by Michael Larabel in BSD on 15 February 2015 at 09:31 AM EST. 13 Comments For anyone that in the past decade has looked for an embedded firewall/network operating system to build your own router or network device has likely encountered m0n0wall. While m0n0wall has been popular over the years and is powered by FreeBSD, the lead d