public void TestNoOp(string host, int port, FtpsSecurityProtocol protocol,
     string user, string pwd, string server)
 {
     using (FtpsClient c = new FtpsClient(host, port, protocol))
     {
         c.AlwaysAcceptServerCertificate = true;
         c.Open(user, pwd);
         Assert.IsTrue(c.IsConnected);
         c.NoOperation();
     }
 }