Murus is a graphical front-end (from Murus.it) for the Mac’s full-fledged, built-in PF (“Packet Filter) network firewall, offering control over inbound connections and heavy-duty features, including “proactive” features like “port knocking” and an adaptive firewall to block brute-force attacks and use blacklists, customizable logging with realtime graphing and statistics, user-defined notifications, connection sharing with access limits and accounting, port forwarding, bandwidth management, a “remote safety switch” and much more. A Murus Assistant app helps quickly configure and enable PF, choose a predefined configuration profile or create your own configurations.
Vallum is a companion application-level firewall that controls outbound connections via a friendly user interface with a configuration assistant, plus a rules editor, log analysis, user-specific rules and geo-IP controls, “fingerprint” matching, and more. (See also: Murus-Vallum comparison.)
Scudo, a new “hybrid firewall” from the company, is an alternative option.