I was recently hounded by a client's strange issue. The client had a Publishing Site which was configured - 'Anonymous Access" - Entire web site. They have fantastic branded home page (I must say, you can't tell it is SharePoint). Anyways, they have an announcements list which shows some announcements on the home page. When you click the announcement it opens the OOB dialog to display the viewform of the list.
Strangely, when you open the view form of an announcement, it gave an authentication popup for anonymous users. Initially, I thought it was perhaps that the form had something which was not published. Nope, every resource published. Then I checked the permissions of the list and it was inheriting from the site.
Then what was it? After a bit of investigation I remembered there was Lockdown feature which blocked form pages in MOSS. But is it still in SP 2010. Yes it is. Still Enabled.
This feature still exists in SharePoint 2010 and is still automatically turned on for Publishing Portal sites. This feature is referred to as lockdown mode and can be turned on or off by enabling/disabling the ViewFormPagesLockdown feature. In this scenario, I want to toggle lockdown mode to off so anonymous users can post comments to the blog site. This is accomplished by using either STSADM or PowerShell. I prefer using PowerShell:
To determine if a site has ViewFormPagesLockdown enabled run the following:
get-spfeature -site http://sitecollectionURL
If ViewFormPagesLockDown is listed, it's enabled.
To toggle lockdown mode to off:
$lockdown = get-spfeature viewformpageslockdown
disable-spfeature $lockdown -url http://sitecollectionURL
If anonymous is already setup, you may need to disable\re-enable anonymous on the site.