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NegotiateStream.AuthenticateAsClient Method (NetworkCredential, String)

Note: This method is new in the .NET Framework version 2.0.

Called by clients to authenticate the client, and optionally the server, in a client-server connection. The authentication process uses the specified client credential.

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

public virtual void AuthenticateAsClient (
	NetworkCredential credential,
	string targetName
public void AuthenticateAsClient (
	NetworkCredential credential, 
	String targetName
public function AuthenticateAsClient (
	credential : NetworkCredential, 
	targetName : String



The NetworkCredential that is used to establish the identity of the client.


The Service Principal Name (SPN) that uniquely identifies the server to authenticate.

Exception typeCondition


The authentication failed. You can use this object to retry the authentication.


The authentication failed. You can use this object to retry the authentication.


This object has been closed.


Authentication has already occurred.

- or -

This stream was used previously to attempt authentication as the server. You cannot use the stream to retry authentication as the client.


targetName is a null reference (Nothing in Visual Basic).

The impersonation level is Identification, the security level is EncryptAndSign, and mutual authentication is requested. The NegotiateStream class will construct the SPN used for mutual authentication.

When authentication succeeds, you must check the IsEncrypted and IsSigned properties to determine what security services are used by the NegotiateStream. Check the IsMutuallyAuthenticated property to determine whether mutual authentication occurred.

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

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

.NET Framework

Supported in: 2.0