Ave, I saw this at the Key.Com website for Keybank Customers. When you go to their website to login to view your account, they ask you to register your computer for the first time. Once your computer is registered, you can access the account using that computer. You can choose to Not register that computer and you won¹t be able to access the account using that computer in future. What exactly are they doing? Can PHP record the MAC Address of the NIC in the computer? Or are they just recording the IP and creating an IP based filteration? I¹m looking to implement a similar security system for one of my applications. Any advice? Rahul S. Johari Supervisor, Internet & Administration Informed Marketing Services Inc. 500 Federal Street, Suite 201 Troy NY 12180 Tel: (518) 687-6700 x154 Fax: (518) 687-6799 Email: rahul@xxxxxxxxxxxxxxxxxxxx http://www.informed-sources.com