AuthenticationSchemeSelectorDelegate Property

HttpListener.AuthenticationSchemeSelectorDelegate Property

Gets or sets the delegate called to determine the protocol used to authenticate clients.

Namespace:  System.Net
Assembly:  System (in System.dll)

Public Property AuthenticationSchemeSelectorDelegate As AuthenticationSchemeSelector
Dim instance As HttpListener 
Dim value As AuthenticationSchemeSelector 

value = instance.AuthenticationSchemeSelectorDelegate

instance.AuthenticationSchemeSelectorDelegate = value

Property Value

Type: System.Net.AuthenticationSchemeSelector
An AuthenticationSchemeSelector delegate that invokes the method used to select an authentication protocol. The default value is Nothing.


This object has been closed.


If you want the same authentication protocol to be used for all requests handled by a particular instance of HttpListener, you do not need to set this property. To specify a protocol to be used for all client requests, use the AuthenticationSchemes property.

If the client has not specified authentication information in its headers, the HttpListener calls the specified delegate for each unauthenticated incoming request to determine which, if any, protocol to use to authenticate the client. The GetContext and EndGetContext methods return an incoming request only if the HttpListener successfully authenticated the request. If a request cannot be authenticated, the HttpListener automatically sends back a 401 response. You can get the identity of a successfully authenticated client using the HttpRequest.LogonUserIdentity property.

The ability to delegate the choice of authentication protocol to an application-specific method is useful if you want an instance of HttpListener to use different authentication protocols depending on the characteristics of the requests it receives (for example, the request's Url or UserHostAddress property).


To set this property to enable Digest, NTLM, or Negotiate requires the SecurityPermission, ControlPrincipal.

The following code example sets the value of this property.

' Set up a listener. 
Dim listener As New HttpListener()
Dim prefixes As HttpListenerPrefixCollection = listener.Prefixes

' Specify the authentication delegate.
listener.AuthenticationSchemeSelectorDelegate = New AuthenticationSchemeSelector(AddressOf AuthenticationSchemeForClient)

' Start listening for requests and process them  
' synchronously.

The following code example provides an implementation of a method invoked by an AuthenticationSchemeSelector delegate.

Private Shared Function AuthenticationSchemeForClient(ByVal request As HttpListenerRequest) As AuthenticationSchemes
    Console.WriteLine("Client authentication protocol selection in progress...")
    ' Do not authenticate local machine requests. 
    If request.RemoteEndPoint.Address.Equals(IPAddress.Loopback) Then 
        Return AuthenticationSchemes.None
        Return AuthenticationSchemes.IntegratedWindowsAuthentication
    End If 
End Function

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

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