System.Net.Security.NegotiateStream.BeginAuthenticateAsServer C# (CSharp) Метод

        public virtual IAsyncResult BeginAuthenticateAsServer(System.Net.NetworkCredential credential, System.Security.Authentication.ExtendedProtection.ExtendedProtectionPolicy policy, System.Net.Security.ProtectionLevel requiredProtectionLevel, System.Security.Principal.TokenImpersonationLevel requiredImpersonationLevel, System.AsyncCallback asyncCallback, object asyncState) { throw null; }
        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback asyncCallback, object asyncState) { throw null; }

 private void AcceptCallback(IAsyncResult ar)
 {
     try
     {
         Socket acceptSocket;
         acceptSocket = server.EndAccept(ar);
         nws = new NetworkStream(acceptSocket);
         ns = new NegotiateStream(nws);
         ns.BeginAuthenticateAsServer(AuthCallback, ns);
     }
     catch (Exception e)
     {
         Console.WriteLine(e.Message);
     }
 }