Extending a web application to allow anonymous access

Perform the following steps

1. In Central Administration under Application Management go to “Manage web applications”.
2. Next select the Web application you wish to extend.
3. In the ribbon Web Applications > under Contribute click “Extend”
4. In the resulting pop-up choose Create new IIS Website and change the Port number and Host header to suit
5. Select NTLM as the Authentication provider and Allow anonymous (to yes), choose SSL as appropriate
6. Under the zone select Internet
7. Clicking ok will extended the web application to a new application pool. This may take a while.
8. Next head to the site through the new port number and you will notice you are still authenticated (i.e. not anonymous). Go to All site settings and “Site permissions”.
9. In the ribbon a new button will be visible with the title “Anonymous access”. Click that and select either:
• Entire Site - will give View items across the entire site for anonymous users 
• Lists and libraries – will allow anonymous users access to the lists and libraries which they are granted access to directly or indirectly (lists with permissions inheriting from parent). You can allow anonymous users permissions to update a list but not a document library, to do this navigate to the list and select permissions. Again select “Anonymous access” and select the rights they should have on the list.