Disable Form Pages for Anonymous Users

If you're running an anonymously accessible MOSS website, especially an internet-facing one, you may have noticed that your SharePoint Forms pages are also accessible to anonymous users. For example, if you're using the publishing features, anonymous users might be able to get to http://SERVER/Pages/Forms/AllItems.aspx. Typically you don't want this, so how do you prevent anonymous users from accessing these pages?
In order to help with this, we provide a Feature out of the box called the ViewFormsPagesLockdown Feature, which we usually just call the Lockdown feature for simplicity. If you're experiencing this problem and want to lock anonymous users out of your Forms pages, then you can execute the following stsadm command on your farm:
 
stsadm.exe –o activatefeature –url <site collection url> -filename ViewFormPagesLockdown\feature.xml

For more details visit technet:
http://technet.microsoft.com/en-us/library/cc263468(office.12).aspx