User account with no Internet, but using file server

Question

I am trying to set up my classroom to where the Internet is only accessible through an Internet User account. I have set up the Internet user and eliminated access to the Internet applications in the Student account. Here are the loopholes when logged in as Student: Using Dashboard weather, a student can click on the city and it will open Safari. In Microsoft Word, a student can open a browser just by typing an address or from the Help menu. If I go into the Account preferences and turn off "Allow supporting programs" it takes care of the student being able to get to the Internet through a back door. BUT it also does not allow connection to a server. When trying to connect to a server, it gives the message "The operation cannot be completed because one or more required items cannot be found (Error code -35)." Does anyone know how I might go about solving this problem?

Answer 1

If you know which IP address range is allocated to your network, you can do this. Open the Sharing pane of System Preferences and shut off the firewall. Next, enter the following into the Terminal in the /Applications/Utilities/ folder:
sudo ipfw add 100 allow ip from any to local.network
sudo ipfw add 110 allow ip from any to any established
sudo ipfw add 120 deny ip from any to any uid shortname
Enter the IP range used by the local network in the first line; you can use a / to specify a range. Examples are 10/8, 172.16/12, and 192.168/16 where the first part of the URL matches the range used by the local network. In the second line, enter the short name of the student account. If you run into problems doing this, use 'sudo ipfw flush' to clear the firewall's rules. You can then reactivate the Mac OS X firewall.
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