Hello, everyone. I've installed Ubuntu 2 months ago and I really like it. But, I come from Windows and I still feel I need to secure my system. I have a lot of roommates and I really don't trust them. We share the same wireless network. How can I make my Ubuntu more secure? I know that Linux is very secure but how do I put extra security layers so that my computer is virtually uncrackable? Thank you for your help.