To check whether the FTP connection is active…

                    /* Check for active FTP connection */
                    var FTPErrorMessage = CheckIfFTPConnectionIsActive();
                    if (string.IsNullOrEmpty(FTPErrorMessage) == false)
                    {
                        throw new Exception(FTPErrorMessage);
                    }

      /// <summary>
        /// CheckIfFTPConnectionIsActive
        /// </summary>
        /// <param name="lessorName"></param>
        private static string CheckIfFTPConnectionIsActive()
        {
            string errorMessage = string.Empty;
            var FtpPath = AppSettingReader.GetStringValue("FtpPath");
            var FtpUserName = AppSettingReader.GetStringValue("FtpUserNameUp");
            var FtpPassword = AppSettingReader.GetStringValue("FtpPasswordUp");

            FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(FtpPath);
            ftp.Credentials = new NetworkCredential(FtpUserName, FtpPassword);
            ftp.KeepAlive = false;
            ftp.Method = WebRequestMethods.Ftp.ListDirectory;
            ftp.UsePassive = false;
            try
            {
              FtpWebResponse response = (FtpWebResponse)ftp.GetResponse();
            }
            catch (WebException ex)
            {
              errorMessage = ex.Status.ToString();
            }
            catch (Exception e)
            {
                errorMessage = e.Message.ToString();
            }
           
            return errorMessage;

        }