• The NSA - the U.S. National Security Agency - has a series of free guides to help the public secure their computers and networks. Their advice ranges from the basic steps to extreme measures, with the idea that you can and should pick and choose what advice you want to follow in locking things down.
• Apple has
• LittleSnitch is a shareware app that alerts you whenever any program on your Mac connects to the internet. Be careful with it: too many or the wrong kind of rules will cause LittleSnitch to prevent normal activity on your computer, like inserting a USB thumbdrive or trying to print. You may have to tone down or turn off some rules to keep it from interfering. If you've ever used ZoneAlarm on Windows, Little Snitch is like ZoneAlarm for OS X.
• NetSetinel is a commercial competitor to LittleSnitch. It's about $80?
• DeepFreeze Mac is a mac version of the popular Windows program, DeepFreeze. $53. It lets you declare certain areas of your hard drive(s) as FROZEN, meaning if any files in the area change, just reboot the mac and DeepFreeze puts them all back the way they were. It's designed for schools where students may change all the settings and install games and otherwise cause computer problems for the teachers and other students. But you can you use it at home the same way, keep your family or employees from messing up your computer. DeepFreeze is a technical tool, so plan to set aside time to experiment and learn how to use it.