autologin anonymous users to enterprise portal

Hi. I want to automatically login users as guest on my enterprise portal. Therefore I configured a user guest with the appropriate rights and checked “allow anonymous login” under Administration/Setup/Internet/Websites/Setup, as Logo name I entered the guest account that I had created. Once I enter the enterprise portal I am automatically logged in, but it looks like I’m logged in as Administrator rather than with my guest account, since there are no restrictions. If I explicitly login with the guest account though, I get exactly the rights that I chose when creating the account. How can I automatically login users with (only) the guest account privileges?