How to: Turn on Leopard’s Firewall and Disable Unneeded Services

Mac OS 10.5 comes with a built-in firewall. By default, it’s not turned on. You can explore it by opening System Preferences > Personal > Security. The default setting is to allow all incoming connections. Clicking “Allow only essential services” will allow incoming traffic for what Leopard thinks is important. “Set access for specific services and applications” lets you specify which programs should and shouldn’t receive incoming traffic.The Advanced… button lets you enable “stealth mode,” which gives unwanted traffic the silent treatment.

Click the back arrow, and click on Sharing in the Internet & Network row. Inside Sharing is a list of services that Daniel Adinolfi suggests should be left off if they’re not being used. Consider each of these services a different way for an attacker to compromise your Mac. Only activate the ones you’re using, to minimize risk.

If you select “Set Access for specific services and applications,” you can either add things manually to the list or wait for the Mac to ask you whether to allow or block the incoming connections.

There’s no reason for us to share anything on this Mac, so all of the services are turned off. If we decide we need screen sharing later, we’ll turn it on. But once we’re done, we’ll turn it off again.

In general, Adinolfi advises, the way to secure your Mac is to keep all of its software patched and updated, use strong passwords, don’t install random software that you don’t fully trust, avoid using accounts with administrative access, back up regularly, run antivirus software, use the built-in firewall, and disable any services that aren’t necessary.

Nicholas Raba, CEO of SecureMac.com, offers some basic tips to keep computers secure from anyone with physical access 
to them. “Some good first steps include setting up a screen-saver password to lock down your machine when you are away, using the built-in FileVault feature of Mac OS X to protect your personal files, and setting up a firmware password to prevent users from bypassing startup security to gain access to your system,” says Raba.

Another way to stay ahead of the curve is by keeping track of new Mac-specific threats as they emerge. SecureMac.com is one source of news for weaknesses and exploits found on the Mac. While the company sometimes uses the news there to promote sales of MacScan, its anti-spyware scanner, it also links to security bulletins posted by other security software companies.

How will you protect your Mac? 
It can be difficult to justify the purchase of antivirus software for a Mac, knowing that the threat of Mac viruses is so small. Antivirus software publishers realize this, so they program their apps to root out a variety of threats, including Mac Trojan horses and Windows viruses.

One of the ways a Mac can be part of a virus problem is by passing on Windows viruses to people who use Windows. While Mac users may not see this as a problem, network administrators trying to contain viruses do. Information-security pro Weisman uses the freeware ClamXav antivirus software (www.clamxav.com) at home.

Symantec’s Romo would likely approve of Weisman’s choice. “I think users should check out the free solutions out there too,” Romo says. “If you are [sharing] lots of files with Windows users, it’s just good computing to make sure you are not spreading viruses.”
Windows viruses can also affect Mac users unintentionally when a Mac user emails a file infected with a Windows virus. Some email hosts run antivirus software that rejects infected files, possibly preventing the email from reaching the recipient.

Security software publishers are naming and marketing their products in recognition that most threats on the Mac do not come from viruses. SecureMac MacScan ($29.99, macscan.securemac.com), for instance, looks for spyware, Trojan horses, and keystroke loggers, and removes them. It also scans for certain cookies that the company says could be used to track users’ online behavior.
Intego (www.intego.com) offers a diverse lineup of security software: FileGuard, which provides encryption; NetBarrier, which provides a firewall, network-intrusion detection, privacy-protection measures to alert users when an application is trying to use the Internet, and network monitoring; and VirusBarrier, which is software to guard against viruses. The titles are also available in Internet Security Barrier bundles.

Sophos Anti-Virus is intended for small businesses ($195 a year for up to five users, www.sophos.com). Sophos also offers its Security Suite ($332.50 per year for up to five users), which aims to shield small-business Macs from viruses, hackers, and spam. McAfee VirusScan ($39.99, www.mcafee
.com) looks for “all types of viruses and other malicious code” when it scans, according to its website. And Avast! Antivirus Mac Edition ($39.95 for 1 year, www.avast.com) advertises that it protects against “the latest malware threats.”

Symantec’s Norton brand of products include Norton Confidential for Macintosh ($49.99 for 1 year, www.symantec.com), which integrates with Safari to protect against phishing attacks as well as offering other identity-protection features. Symantec also offers Mac versions of Norton Personal Firewall ($49.95) and Norton AntiVirus ($49.95).