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AuthenticationManager.PreAuthenticate Method

Preauthenticates a request.

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

public static Authorization PreAuthenticate(
	WebRequest request,
	ICredentials credentials


Type: System.Net.WebRequest
A WebRequest to an Internet resource.
Type: System.Net.ICredentials
The ICredentials associated with the request.

Return Value

Type: System.Net.Authorization
An instance of the Authorization class if the request can be preauthenticated; otherwise, null. If credentials is null, this method returns null.


request is null.

If the authentication module can preauthenticate the request, the PreAuthenticate method returns an Authentication instance and sends the authorization information to the server preemptively instead of waiting for the resource to issue a challenge. This behavior is outlined in section 3.3 of RFC 2617 (HTTP Authentication: Basic and Digest Access Authentication). Authentication modules that support preauthentication allow clients to improve server efficiency by avoiding extra round trips caused by authentication challenges.

Authorization modules that can preauthenticate requests set the IAuthenticationModule.CanPreAuthenticate property to true.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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