I just finished setting up the three little pigs siri proxy on my ubuntu server 10.10. Its a public server, but I might have an idea to make it private. I want to be able to use the server on wifi and 3g so I know I can't only accept certain ip address on my servers. Correct me if I am wrong but mac addresses don't change right? So my question is how could I block all mac addresses except the ones of the devices that are allowed to use my server? Is something like that possible. Could someone recommend a better solution? I am new to linux.