How to not allow access if not logged in?

What is the best way to allow internet access but protect the internal network?

• Background: I have created an internal wireless network using a single server computer and a wireless router. Users can create and share proprietary content with other users on the same internal network. I have access to a wired internet connection near the server (ie, I can connect a LAN cable from the server to the wall jack). What I would like to do is: 1) Allow internal network users to access the internet 2) Allow the server to access the internet (for software updates, etc.) AND 3) Prevent anyone outside of our network from seeing or accessing our internal content I've searched for answers, but I haven't found a clear solution for what I'm trying to do. I'm hoping it's a fairly easy question since this situation must come up regularly. Thank you!

• Answer:

  You need to configure this in your router. Just use a secure network setting and turn off broadcast SID.