Your April edition ( Mac|Life 139) lists a program in the “Find rogue apps slowing your Mac” tutorial called KnockKnock. Where do I find this program? I did a search on the internet and in the Apple Store but I couldn’t find it. What am I doing wrong? Bob Cu lbert On step five of the tutorial you should see the link — objective-see.com. Click on the KnockKnock link and download button. Double click the Zip to extract the app, then drag it to the Applications folder.