If you’re running OS X Mountain Lion (or Lion 10.7.5) you may have had this notice pop up when you tried to open or run an application:

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Well, don’t worry, you’ve done nothing wrong. It’s just an extra layer of security Apple added in OS X Mountain Lion (10.8) and also in the OS X Lion 10.7.5 update.

The idea behind Gatekeeper is to help prevent opening or running malicious applications that might compromise your security, or just adversely affect your system performance. Gatekeeper does this by giving you three options:

Mac App Store – this only allows application downloaded via the Mac App Store to be opened.

Mac App Store and identified developers – this allows App Store applications and also apps that have been signed with a key the developer has obtained from Apple.

Anywhere – this allows applications that you have downloaded from anywhere.

 

If you’ve gone and thrown Gatekeeper at Google you may have seen some posts advising you to change your Gatekeeper preference to “Anywhere“.

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While this may seem to solve the issue and allow you to install the application you want, I would advise against it. By setting Gatekeeper to Anywhere you’re totally disabling a security feature. Not a good idea in this day and age. The best way to deal with this is to set Gatekeeper to Mac App Store and identified developers

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then if you get the warning dialogue telling you that the app cannot be installed because it is from an unidentified developer, you can do two things:

1. Stop and think if you really want to open the app and trust where it came from, i.e. from the developers (makers) website or another place that might not seem very reputable?

2. If you decide you need and trust the application, then you can control click or right click (if enabled) the application and select Open

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You may be asked for an administrator name and password after you select Open. You should only have to do this the first time you open such an application, after this you will be able to open this application like any other app, either double clicking or via Launchpad etc…

 

So, there you go, a way to keep your security and open the applications you choose to open.