Thanks, we could all use some education on this subject.Well, it depends, if your wifi network is encrypted, then it will be difficult to find out the MAC address, as the encryption has to be cracked first.Originally Posted by RAC
I would have thought that it would be a "challenge" to guess the few MAC addresses that were configured, unless it is possible to extract them from the router configuration.
But if the Wifi is unencrypted, it is simply a matter of listening to the devices on the same network. This can be done directly from Windows/Mac with the help of a sniffing tool. Since each device on the network sends along it's MAC as a means of identification, is it fairly straight forward to obtain the MAC. Once you have it, you would simply use a tool like MacMakeUp to change your own MAC to one of the devices, which are allowed to connect. Identical MAC's will lead to a conflict and one of the devices will be kicked out. So you would have to wait for the other device to leave the network.
Anyhow, the point being, no one guesses MAC's, as you mentioned that would be quite a challenge. You could use MAC filtering in conjunction with WPA encryption and it will be fairly safe, but not because of the MAC filter, because again, as soon as the password is known, a MAC filter can be easily rendered useless.
Hopefully this post has not yet crossed the borderline, it definitely wasn't intended too. It has merely an educational purpose.