I don't know anything about parental controls on the Mac (even though I am presently typing on a MacBook). The only issue that initially comes to mind is that DrJava actually consists of two Java Virtual Machines (each one is a separate process as far the operating system is concerned) that use RMI to communicate with each other. RMI potentially supports communication across the internet but we simply use it to communicate between two JVMs running on the same computer. To create the second JVM, the initial DrJava process spawns a second process to run the JVM. I don't know how you would tell the parental controls to allow the second process launch and communication (using TCP/IP) between the two JVMs.