OPNsense is an open-source firewall and routing distribution built on FreeBSD, offering a polished web interface for stateful filtering, intrusion detection, VPN (IPsec, OpenVPN, WireGuard), traffic shaping, and captive portals. Forked from pfSense in 2015 with a focus on faster release cycles, weekly security patches, and community-driven governance, it gives homelab users and businesses a transparent alternative to costly commercial firewall appliances.