I need to know the MAC and the IP address of the connect clients, how can I do this in PHP?
too late to answer but here is my approach since no one mentioned this here:
why note a client side solution ?
a javascript implementation to store the mac in a cookie (you can encrypt it before that)
then each request must include that cookie name, else it will be rejected.
to make this even more fun you can make a server side verification
from the mac address you get the manifacturer (there are plenty of free APIs for this)
then compare it with the user_agent value to see if there was some sort of manipulation:
a mac address of HP + a user agent of Safari = reject request.