Mac Firewalls

Do Mac users need a firewall?

Macintosh pundits disagree about the need for security. Apple's operating systems are structured differently than Windows operating systems and are less vulnerable to attack. In addition, since Apple systems represent a minority market share, they have been less attractive targets for malicious hackers. Mac users running OS X already have a firewall included in the operating system. By default, the Mac firewall closes the most-exploited ports, requiring users to actively enable ports for file sharing, print sharing or personal web hosting.

Britain's The H newsletter has the most comprehensive and well-documented review, and JŸrgen Schmidt notes, "The Mac OS X Leopard firewall failed every test. It is not activated by default and, even when activated, it does not behave as expected. Network connections to non-authorized services can still be established and even under the most restrictive setting."

Part of the issue is the default settings. The Leopard firewall blocks only inbound connections, meaning it won't prevent spyware from "phoning home" with your sensitive data or browser history. For that reason, Macworld.com authors Rich Mogull and Chris Pepper suggest enabling the second packet-filtering firewall (included with Mac OS X but disabled by default), which can control outbound traffic as well. Since getting the settings right can be confusing for novices, they recommend using a third-party application like Hanynet WaterRoof (for advanced users) or NoobProof (for less experienced users); both are free.

While Mogull and Pepper conclude that "for most users, the firewalls built into OS X are enough," Macworld.com does review several third-party firewalls. Little Snitch (*Est. $30) from Objective Development gets the highest rating among the latest standalone firewall offerings. According to Mogull and Pepper, Little Snitch is pre-configured not to interfere with safe surfing, while allowing the user to control inbound and outbound connections. It also has a network monitor, which shows users which programs are accessing their network. The reviewers recommend Little Snitch "for those whose computers are always online, or are often online in public places."

Many free firewall programs have been developed for Linux. However, none of these have been formally reviewed by any well-regarded critics. Tech-FAQ describes a dozen of them and has links; see Useful Links for more information.