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DefaultAuthenticationEventHandler Delegate

Represents the method that handles the DefaultAuthentication_OnAuthenticate event of a DefaultAuthenticationModule.

Namespace:  System.Web.Security
Assembly:  System.Web (in System.Web.dll)

public delegate void DefaultAuthenticationEventHandler(
	Object sender,
	DefaultAuthenticationEventArgs e
)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Web.Security.DefaultAuthenticationEventArgs

A DefaultAuthenticationEventArgs that contains the event data.

The DefaultAuthenticationEventHandler delegate is defined for the Authenticate event of the DefaultAuthenticationModule class. You can access the Authenticate event of the DefaultAuthenticationModule class by specifying a subroutine named DefaultAuthentication_OnAuthenticate in the Global.asax file for your ASP.NET application. The Authenticate event is raised after the AuthenticateRequest event and is used to ensure that the User property of the current HttpContext is populated with an IPrincipal object.

You can use the Context property of the DefaultAuthenticationEventArgs object supplied to the DefaultAuthentication_OnAuthenticate event to set the User property of the current HttpContext to a custom IPrincipal object. If you do not specify a value for the User property of the HttpContext supplied during the DefaultAuthentication_OnAuthenticate event, the DefaultAuthenticationModule sets the User property of the HttpContext to a GenericPrincipal object that contains no user information.

The DefaultAuthentication_OnAuthenticate event is raised after the AuthenticateRequest event and before the AuthorizeRequest event. If you have an authorization section that depends on the user name to deny or allow access to your application, modifying the User property of the current HttpContext can affect the behavior of your application. Be sure that the user name you set during the DefaultAuthentication_OnAuthenticate event is considered when you specify the authorization section in your configuration.

The following code example uses the DefaultAuthentication_OnAuthenticate event to test whether the User property of the current HttpContext is null. If the property is null, the sample sets the User property of the current HttpContext to a GenericPrincipal object, where the Identity of the GenericPrincipal object is a GenericIdentity with a Name value of "default".

NoteNote

The DefaultAuthentication_OnAuthenticate event is raised before the AuthorizeRequest event. As a result, if you set the User property of the current HttpContext to a custom identity, it can affect the behavior of your application. For example, if you are using the FormsAuthentication class and you are ensuring that only authenticated users have access to your site, by using the authorization section and specifying <deny users="?" />, this sample will cause the deny element to be ignored, as the user will have a name, which is "default". Instead you would specify <deny users="default" /> to ensure that only authenticated users can access your site.

public void DefaultAuthentication_OnAuthenticate(object sender,
                                                 DefaultAuthenticationEventArgs args)
{
  if (args.Context.User == null)
    args.Context.User = 
      new System.Security.Principal.GenericPrincipal(
        new System.Security.Principal.GenericIdentity("default"),
        new String[0]);
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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