im new to mac and have a few questions 1. my shared tab in the finder has some unknown computers listed, and when i select any of them, it says connected as guests. and also i can see their shared folder. anybody knows why? and when i activate my firewall, the above mentioned computers disappear. am i being hacked? 2. another problem is when i activate the firewall my internet stops working on the laptop which im sharing via airport of my iMac. i dont know if my internet modem has built-in firewall, dont know how to check either. 3. how do i setup password for internet sharing? thanks guys..