Setup a wordpress multisite network on AWS EC2 (4)

Update 12/29/2012: I just came across Stephen White's instruction: It walked through the setting up of FTP service itself on EC2 if you haven't done that yet.  The valuable part I picked up is forbidding FTPuser to open a shell, and stopping WordPress continually asking for your FTP login details. But in the user permission setting part, he didn't restrict …