I read in a book that "Anonymous access is a requirement for FBA; otherwise, users never see the logon page." Is it really so?

In my experience this is not true as I have a FBA web application and I haven't flagged the anonymous checkbox in Central Administration/Web Application/Authentication provider. Still, I see the logon page and the site works well.

EDIT: enter image description here

1 Answer 1


"Anonymous" means two things:

  • From a technical point of view (or "identification/who are you?"), you must set "Anonymous" access in IIS. This is for IIS to allow any un-authenticated request to come in, and display the FBA logon page, without IIS interfering for authentication.
    This means IIS does not handle anymore the authentication through Windows-integrated mechanisms. Anonymous is automatically set at IIS-level when you configure your SharePoint Web app to use FBA. IIS, who usually identifies and knows the users, now delegates this step to SharePoint and does not authenticate users anymore.
  • From a functionnal point of view (or "authorization/what can you view or do?"), it means SharePoint allows site collections administrators to switch their sites to Anonymous mode.
    If they do it, content can then be displayed to anonymous users. SharePoint has to allow this at its own level. This is what you do by enabling Anonyous from the CA (and then from the Site collection settings).
  • so you are saying that the "Anonymous requirement" is referred to IIS?
    – Gyonder
    Commented Mar 30, 2016 at 9:27
  • As I did nor read or write the book you're mentionning, I can only imagine it's about IIS... But I'm quite confident it is the case.
    – Evariste
    Commented Mar 30, 2016 at 9:29
  • You might be right but when you create a new web application, either FBA or Windows authentication, it is already "Anonymous" enabled on the IIS side. So it shouldn't be a requirement for FBA only. Anyway, I edited the post with a screenshot and I think it refers to Sharepoint as the picture come the central administration.
    – Gyonder
    Commented Mar 30, 2016 at 9:41
  • 3
    I think this is a mistake from the author. I'm confident you don't need to enable Anonymous at the SharePoint-level for FBA Web apps. It works without it, and it does not make sense from a technical point of view. It's automatically set in IIS, and that's what we need. You may try to contact the author if possible to point him to that highly presumed mistake.
    – Evariste
    Commented Mar 30, 2016 at 10:42
  • 1
    Right, you do not need to enable anonymous at the SharePoint level (Web Application or higher). You do need to leave anonymous enabled at the IIS level, which is done automatically for you when you enable Claims authentication of any sort (Windows, SAML, FBA). @Evariste has this 100% correct.
    – user6024
    Commented Mar 30, 2016 at 14:41

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