NegotiateStream.BeginAuthenticateAsServer Method (NetworkCredential, ProtectionLevel, TokenImpersonationLevel, AsyncCallback, Object)

Called by servers to begin an asynchronous operation to authenticate the client, and optionally the server, in a client-server connection. The authentication process uses the specified server credentials and authentication options. This method does not block.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public virtual IAsyncResult BeginAuthenticateAsServer(
	NetworkCredential credential,
	ProtectionLevel requiredProtectionLevel,
	TokenImpersonationLevel requiredImpersonationLevel,
	AsyncCallback asyncCallback,
	Object asyncState
)

Parameters

credential
Type: System.Net.NetworkCredential
The NetworkCredential that is used to establish the identity of the client.
requiredProtectionLevel
Type: System.Net.Security.ProtectionLevel
One of the ProtectionLevel values, indicating the security services for the stream.
requiredImpersonationLevel
Type: System.Security.Principal.TokenImpersonationLevel
One of the TokenImpersonationLevel values, indicating how the server can use the client's credentials to access resources.
asyncCallback
Type: System.AsyncCallback
An AsyncCallback delegate that references the method to invoke when the authentication is complete.
asyncState
Type: System.Object
A user-defined object containing information about the operation. This object is passed to the asyncCallback delegate when the operation completes.

Return Value

Type: System.IAsyncResult
An IAsyncResult object indicating the status of the asynchronous operation.

ExceptionCondition
ArgumentNullException

credential is null.

ArgumentOutOfRangeException

requiredImpersonationLevel must be Identification, Impersonation, or Delegation,

AuthenticationException

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

InvalidCredentialException

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

ObjectDisposedException

This object has been closed.

InvalidOperationException

Authentication has already occurred.

- or -

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

NotSupportedException

Windows 95 and Windows 98 are not supported.

Use the requiredProtectionLevel parameter to request security services for data transmitted using the authenticated stream. For example, to have the data encrypted and signed, specify the EncryptAndSign value. Successful authentication does not guarantee that, the requested ProtectionLevel has been granted. You must check the IsEncrypted and IsSigned properties to determine what security services are used by the NegotiateStream.

This method is asynchronous and does not block while the operation completes. To block until the operation completes, use one of the AuthenticateAsServer method overloads.

The asynchronous authentication operation must be completed by calling the EndAuthenticateAsServer method. Typically, the method is invoked by the asyncCallback delegate. For detailed information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously

If the authentication fails, you receive an AuthenticationException or an InvalidCredentialException. In this case, you can retry the authentication with a different credential.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition Platform Note: The AuthenticateAsServer method is not supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.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.
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