How to check whether the application is single sign on or form authentication from C# code?

Suppose you have a C# web application which need to run on a internal (inside network) and external (DMZ) web servers. These two application talks to the same database. The internal application need single sign on (SSO) and the external application is form authentication. Now in Visual studio you have one project for both these applications. Depending on the web.config’s configurations the application either do SSO or form authentication.

For SSO the web.config settings are,
<authentication mode="Windows"></authentication>

For form the web.config settings are,
<authentication mode="Forms">
<forms name="LegalAidLogin" loginUrl="~/login.aspx" defaultUrl="~/default.aspx" timeout="30" protection="All" enableCrossAppRedirects="true">

Now, when you in login page which you have to need to check the authentication mode on page load, use the code below,

// Load web.config
System.Xml.XmlDocument config = new System.Xml.XmlDocument();
System.Xml.XmlNode node = config.SelectSingleNode(”//configuration/system.web/authentication”);

// Check the login mode for forgot your password
if (node.Attributes[“mode”].Value == “Forms”)

If you are already login in and you need to check the authentication mode use code below,

if (HttpContext.Current.User.Identity.AuthenticationType != “Forms”)


Diganta Kumar has architected and developed software for more than a decade for a wide range of industries and development platforms and over the years has filled many roles including program manager, founder, developer, architect, team lead, mentor and project manager. Diganta is founder of two online IT businesses. He is a certified AWS Solutions Architect, certified Professional Scrum Master (PSM I), certified Professional Scrum Developer (PSD I) and ITIL Certified. He has presented at Microsoft Tech.Ed, Microsoft AppFest and Ark Group Intranet conference. He attends AWS Seattle Official Events, Seattle AWS Architects-Engineers, and AWS Cloud Commerce user groups. He likes to help, mentor and manage software development teams to improve and produce great software. He currently work as a Senior Technical Program Manager for Amazon Web Services.

Posted in C#

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