I have a Linksys WRT54G2 wireless router that is used in an office setting. We have, of course, set a password to access (wireless) the internet and local file sharing network from a laptop. Occasionally, however, we have guests that want to access the internet. Is it possible to give the guest a temporary password that is different than the main one? Also, is it possible to limit the guest to only the internet and not the local file sharing network?
Not a simple thing to do. You would have to have a radius server and use enterprise mode WPA.
The other way some routers do this is with a guest SSID and many have a feature to prevent the guest and the main network from talking. Still the so called password is just the key for the guest SSID so all the users have the same one and it is a pain to change. BUT your router does not have this feature. You might look into running dd-wrt software on your router but this is still has the password sharing problem.
There are also server based solution but those still require a second SSID in most cases.