NegotiateStream.BeginAuthenticateAsServer Method (AsyncCallback, Object)


Called by servers to begin an asynchronous operation to authenticate the client, and optionally the server, in a client-server connection. This method does not block.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public virtual IAsyncResult BeginAuthenticateAsServer(
	AsyncCallback asyncCallback,
	object asyncState


Type: System.AsyncCallback

An AsyncCallback delegate that references the method to invoke when the authentication is complete.

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.

Exception Condition

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.


Windows 95 and Windows 98 are not supported.

The authentication uses the server's DefaultCredentials. No Service Principal Name (SPN) is specified for the server. The impersonation level is Identification, the security level is EncryptAndSign.

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.

To block until the operation completes, use one of the AuthenticateAsServer method overloads.

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


The AuthenticateAsServer method is not supported.

.NET Framework
Available since 2.0
Return to top