General OS X Security
When many people get Mac computers for the first time, they jump right into using OS X, but never take the time to adjust Mac internet security and advanced settings. Adjusting these settings on your Mac computer will adjust how OS X works. Thus, improving overall security. Although some of these settings do not directly improve internet security, they are still good to adjust, as they effect OS X as a whole. The majority of these settings will improve OS X internet security in one way or another.
To start, open up your Mac’s system preferences by clicking the system preferences icon in the dock. If you have removed the system preferences icon, you can navigate to it using the path: Finder > Applications > System Preferences.
Adjust OS X Security Options:
From within System Preferences, click the Security icon. Under the first tab, General, make adjustments to the settings to fit your own preferences. After you are finished, click the next tab, FileVault.
FileVault is a setting that will encrypt all of the data in your home folder. Should you ever get hacked, encrypted files will be unreadable to the person who steals them. FileVault is not always necessary, although it is a nice precaution to have. If you want to encrypt you home folder, click the Turn on FileVault button. You also have the option to set a master password from the FileVault tab. If you wish to set a password to be used for all accounts on your Mac, go ahead and set the password. Do not lose it!
Click the Firewall tab. The Firewall is going to help improve internet security on your Mac. Click the advanced button. Under the advanced drop down menu, put a check mark next to "Block all incoming connections" and "Enable stealth mode". Upon doing so, you will get the following message:
The firewall will block all sharing services, such as file sharing, screen sharing, iChat Bonjour, etc.
Read this message and assure that you are fine with everything before choosing to Block all incoming connections. Press the OK button when you are finished. If your firewall is not on, make sure that you click the Start button to start your firewall.
Adjust OS X Sharing Options:
From System Preferences, click the Sharing icon. Within this window, you should see several services listed along the right hand side. For example, DVD or CD Sharing, Screen Sharing, File Sharing, Printer Sharing, etc. You can click on each one of these settings to see more details and configure advanced options. To turn a service completely on or off, simply click next to the service to check or uncheck a service. When you are finished, you can exit the System Preferences window.
Safari, being the default internet browser of OS X, has a couple of settings that you can adjust for better overall security. By adjusting these settings, you will change the way Safari handles certain situations.
To start, launch Safari by choosing it from the dock or navigating the path: Finder > Applications > Safari. After Safari opens, click the Safari heading from the top OS X menu bar and select Preferences from the drop menu.
Under the first tab, General, you may want to adjust the settings for Remove history items, Save downloaded files to, and Remove download list items. One thing that you need to change is the part that says "Open "safe" files after downloading. Do NOT open safe files after downloading. Make sure that this box is unchecked. The reason for this is: Safari will automatically open certain file extensions that it believes are safe (for example, pictures, movies, etc.) upon download. However, files like pictures, movies, etc, can contain viruses. That’s why you don’t want to be automatically opening stuff.
From within Safari Preferences, click the Security tab. Make sure that all options under Fraudulent sites and Web content are checked. Under the section Accept cookies, click the option for "Only from sites I visit".
When you are finished, you can close Safari.
More Internet Security for Macs
By adjusting all of the above settings, you should be able to setup OS X to be secure as possible using the built-in settings. The main thing to consider with Mac internet security is: don’t visit sites that seem fishy, and always adjust your broswer’s settings. You probably already know that Macs do not get a lot of viruses, but the possibility is always there. It’s always best to use a good antivirus software. One last recommendation is to use the application Little Snitch, which allows you to configure several advanced internet connection settings for specific apps.