FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://xx.xxx.xxx.xx/");
request.Method = WebRequestMethods.Ftp.ListDirectory;
request.Credentials = new NetworkCredential("<UserName>", "<Password>");

request.EnableSsl = true;
ServicePointManager.ServerCertificateValidationCallback = delegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };