Для Ftp- это примерно так:

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;

    public class GetFiles
    {
             
        private string ftpUri = "ftp://ftp.server.net/directory/";
        private string Pass = "password";
        private string User = "user";

        public List<string> GetFilesFromFtpServer()
        {
            List<string> fileList = null;
            FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(ftpUri);
            request.Method = WebRequestMethods.Ftp.ListDirectory;
            request.Credentials = new NetworkCredential(User, Pass);
            //request.UsePassive = false;
            FtpWebResponse response = (FtpWebResponse)request.GetResponse();
            Stream responseStream = null;
            StreamReader readStream = null;
            try
            {
                responseStream = response.GetResponseStream();
                readStream = new StreamReader(responseStream, System.Text.Encoding.UTF8);
                if (readStream != null)
                {
                    string line;
                    fileList = new List<string>();
                    do
                    {
                        line = readStream.ReadLine();
                        if (line != null)
                            fileList.Add(line);
                    } while (line != null);
                }
            }
            finally
            {
                if (readStream != null)
                {
                    readStream.Close();
                }
                if (response != null)
                {
                    response.Close();
                }
            }
            return fileList;
        }
    }