Default [Q] Can't Root Galaxy S3 running 4.3

Hello All-
I previously had a Galaxy S3 running Android 4.2. It is At&T and i am a Mac user. It was rooted and In ran Cyanogen 10.2. To make a long story short, it started dropping every call and AT&T finally replaced it .

They replaced it with another Galaxy S3 running jellybean 4.3 and it has knox. Have spent countless hours trying to root this phone if for no reason than to get the Samsung and AT&T bloatware off of it. It will not root and I can not find any articles on how to root S3 with Jellybean on a MAC. I have also tried to remove Knox and it won't go away. I am at the end of my rope. Remember that I am trying to do this on a MAC.

Thanks in advance for the help!