// Your FTP site
string ftpPath = "ftp://some/localtion/to/ftp/directory/";
 
// Some expression to match against the files...do they have a consistent name? This example would find XML files that had 'some_string' in the file name
Regex matchExpression = new Regex("^some_string.+\.xml$", RegexOptions.IgnoreCase);
 
// Only files greater than this value
DateTime cutOff = DateTime.Now.AddDays(-10);
 
List<ftplineresult> results = FTPHelper.GetFilesListSortedByDate(ftpPath, matchExpression, cutOff);
</ftplineresult>

namespace FTP.Utilities
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Net;
    using System.IO;
    using System.Text.RegularExpressions;
    public enum ListStyle
    {
        Unix,
        Windows
    }
    public class FTPLineResult
    {
        public ListStyle Style { get; set; }
        public string Name { get; set; }
        public DateTime DateTime { get; set; }
        public bool IsDirectory { get; set; }
        public long Size { get; set; }
    }
    /// <summary>
    /// from http://blogs.msdn.com/adarshk/archive/2004/09/15/230177.aspx
    /// </summary>
    public class FTPLineParser
    {
        private Regex winStyle = new Regex(@"^(?<month>\d{1,2})-(?<day>\d{1,2})-(?<year>\d{1,2})\s+(?<hour>\d{1,2}):(?<minutes>\d{1,2})(?<ampm>am|pm)\s+(?<dir>[<]dir[>])?\s+(?<size>\d+)?\s+(?<name>.*)$", RegexOptions.IgnoreCase);
        public FTPLineResult Parse(string line)
        {
            Match match = winStyle.Match(line);
            if (match.Success)
            {
                return ParseMatch(match.Groups, ListStyle.Windows);
            }
            throw new Exception("Invalid line format");
        }
        private FTPLineResult ParseMatch(GroupCollection matchGroups, ListStyle style)
        {
            string dirMatch = (style == ListStyle.Unix ? "d" : "<dir>");
            FTPLineResult result = new FTPLineResult();
            result.Style = style;
            result.IsDirectory = matchGroups["dir"].Value.Equals(dirMatch, StringComparison.InvariantCultureIgnoreCase);
            result.Name = matchGroups["name"].Value;
            result.DateTime = new DateTime(2000 + int.Parse(matchGroups["year"].Value), int.Parse(matchGroups["month"].Value), int.Parse(matchGroups["day"].Value), int.Parse(matchGroups["hour"].Value) + (matchGroups["ampm"].Value.Equals("PM") && matchGroups["hour"].Value != "12" ? 12 : 0), int.Parse(matchGroups["minutes"].Value), 0);
            if (!result.IsDirectory)
                result.Size = long.Parse(matchGroups["size"].Value);
            return result;
        }
    }
    /// <summary>
    /// FTP Class to retreieve files that match an expression and file date cutoff
    /// </summary>
    public class FTPHelper
    {
        /// <summary>
        /// Get a list of files from the FTP server, in a specified path, that match a naming regular expression, and who's file date is after a cutoff
        /// </summary>
        /// <param name="ftpPath">The path the to FTP location</param>
        /// <param name="nameRegex">Regurlar expression to match when finding files</param>
        /// <param name="cutoff">A datetime that files on the FP server must be greater than</param>
        /// <returns></returns>
        public static List<FTPLineResult> GetFilesListSortedByDate(string ftpPath, Regex nameRegex, DateTime cutoff)
        {
            List<FTPLineResult> output = new List<FTPLineResult>();
            FtpWebRequest request = FtpWebRequest.Create(ftpPath) as FtpWebRequest;
            ConfigureProxy(request);
            request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            FtpWebResponse response = request.GetResponse() as FtpWebResponse;
            StreamReader directoryReader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.ASCII);
            var parser = new FTPLineParser();
            while (!directoryReader.EndOfStream)
            {
                var result = parser.Parse(directoryReader.ReadLine());
                if (!result.IsDirectory && result.DateTime > cutoff && nameRegex.IsMatch(result.Name))
                {
                    output.Add(result);
                }
            }
            // need to ensure the files are sorted in ascending date order
            output.Sort(
                new Comparison<FTPLineResult>(
                    delegate(FTPLineResult res1, FTPLineResult res2)
                    {
                        return res1.DateTime.CompareTo(res2.DateTime);
                    }
                )
            );
            return output;
        }
        /// <summary>
        /// set up the web proxy
        /// </summary>
        /// <param name="request"></param>
        private static void ConfigureProxy(FtpWebRequest request)
        {
            request.Proxy = WebRequest.GetSystemWebProxy();
            request.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
        }
    }
}