Most of the UiB campus, including the Department of Mathematics, is covered by a wireless network – “Airport network” in apple-speak.
It is open, but you need to know its SSID to connect. This is “UiB” without the quotation marks. Please note that the SSID is a secret, known only to 20000 people, so don’t tell anyone not related to the university!
However, connecting only to the wireless network won’t get you to the internet right away. For that, open the program “Internet Connect”, for example from the bottom menu choice of the Airport menu. Choose “New VPN connection” from the File menu. Click “PPTP” when you are asked for kind of VPN. Then fill in Server address “vpn-ansatt.uib.no” and Account name “email@example.com”. Type your password and connect. That should do it!
In case of trouble, look at the server names in the Windows guide at the IT-avdelingen or (as long as it works) at http://www.wlan.uib.no/vista/