Forms Based Authentication for SharePoint Extranet

The Requirement: Northamptonshire and Cambridgeshire County Councils have established a shared services partnership to provide common back-office services in an effort to reduce costs. To facilitate this working partnership, a collaboration solution was required that enabled employees from both organisations (and future partners) to work together securely. Having already built an internal collaboration solution using SharePoint for NCC, we advised them it would be relatively simple and cost effective to extend their SharePoint farm to an extranet topology.

NCC had been trialling an extranet SharePoint site, but initial access and authentication provided by Active Directory proved extremely difficult to implement and maintain for those LGSS members outside of NCC. The User Experience had been reported as poor, with login times being lengthy and often failing completely.

We diagnosed the problem as being with latency between the SharePoint servers in the extranet and the Active Directory servers inside the corporate network. Instead of Active Directory for authentication, we instead proposed using a SQL Server based membership provider, together with forms-based authentication for logins.

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Forms-based authentication

Forms-based authentication allows standard HTML pages to be used to capture user credentials, which can then be processed by SharePoint using any asp.net compatible membership provider. The membership provider can effectively use any membership store to be used for credentials. We chose SQL server as an existing provider and administration solution had already been developed and implemented on the NCC’s internet – for school logins. By re-purposing this existing solution, existing in-house knowledge could be used by the support staff.