public class FTPFactory
    {

        private string
            remoteHost, remotePath, remoteUser, remotePass, mes;
        private int remotePort, bytes;
        private Socket clientSocket;

        private int retValue;
        private Boolean debug;
        private Boolean logined;
        private string reply;

        private static int BLOCK_SIZE = 512;

        Byte[] buffer = new Byte[BLOCK_SIZE];
        Encoding ASCII = Encoding.ASCII;

        public FTPFactory()
        {

            remoteHost = "localhost";
            remotePath = ".";
            remoteUser = "anonymous";
            remotePass = "anonymous";
            remotePort = 21;
            debug = false;
            logined = false;

        }

        ///
        /// Set the name of the FTP server to connect to.
        ///
        /// Server name
        public void setRemoteHost(string remoteHost)
        {
            this.remoteHost = remoteHost;
        }

        ///
        /// Return the name of the current FTP server.
        ///
        /// Server name
        public string getRemoteHost()
        {
            return remoteHost;
        }

        ///
        /// Set the port number to use for FTP.
        ///
        /// Port number
        public void setRemotePort(int remotePort)
        {
            this.remotePort = remotePort;
        }

        ///
        /// Return the current port number.
        ///
        /// Current port number
        public int getRemotePort()
        {
            return remotePort;
        }

        ///
        /// Set the remote directory path.
        ///
        /// The remote directory path
        public void setRemotePath(string remotePath)
        {
            this.remotePath = remotePath;
        }

        ///
        /// Return the current remote directory path.
        ///
        /// The current remote directory path.
        public string getRemotePath()
        {
            return remotePath;
        }

        ///
        /// Set the user name to use for logging into the remote server.
        ///
        /// Username
        public void setRemoteUser(string remoteUser)
        {
            this.remoteUser = remoteUser;
        }

        ///
        /// Set the password to user for logging into the remote server.
        ///
        /// Password
        public void setRemotePass(string remotePass)
        {
            this.remotePass = remotePass;
        }

        ///
        /// Return a string array containing the remote directory's file list.
        ///
        ///
        ///
        public string[] getFileList(string mask)
        {

            if (!logined)
            {
                login();
            }

            Socket cSocket = createDataSocket();

            sendCommand("NLST " + mask);

            if (!(retValue == 150 || retValue == 125))
            {
                throw new IOException(reply.Substring(4));
            }

            mes = "";

            while (true)
            {

                int bytes = cSocket.Receive(buffer, buffer.Length, 0);
                mes += ASCII.GetString(buffer, 0, bytes);

                if (bytes < buffer.Length)
                {
                    break;
                }
            }

            char[] seperator = { '\n' };
            string[] mess = mes.Split(seperator);

            cSocket.Close();

            readReply();

            if (retValue != 226)
            {
                throw new IOException(reply.Substring(4));
            }
            return mess;

        }

        ///
        /// Return the size of a file.
        ///
        ///
        ///
        public long getFileSize(string fileName)
        {

            if (!logined)
            {
                login();
            }

            sendCommand("SIZE " + fileName);
            long size = 0;

            if (retValue == 213)
            {
                size = Int64.Parse(reply.Substring(4));
            }
            else
            {
                throw new IOException(reply.Substring(4));
            }

            return size;

        }

        ///
        /// Login to the remote server.
        ///
        public void login()
        {

            clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPEndPoint ep = new IPEndPoint(Dns.Resolve(remoteHost).AddressList[0], remotePort);

            try
            {
                clientSocket.Connect(ep);
            }
            catch (Exception)
            {
                throw new IOException("Couldn't connect to remote server");
            }

            readReply();
            if (retValue != 220)
            {
                close();
                throw new IOException(reply.Substring(4));
            }
            if (debug)
                Console.WriteLine("USER " + remoteUser);

            sendCommand("USER " + remoteUser);

            if (!(retValue == 331 || retValue == 230))
            {
                cleanup();
                throw new IOException(reply.Substring(4));
            }

            if (retValue != 230)
            {
                if (debug)
                    Console.WriteLine("PASS xxx");

                sendCommand("PASS " + remotePass);
                if (!(retValue == 230 || retValue == 202))
                {
                    cleanup();
                    throw new IOException(reply.Substring(4));
                }
            }

            logined = true;
            Console.WriteLine("Connected to " + remoteHost);

            chdir(remotePath);

        }
///
        /// If the value of mode is true, set binary mode for downloads.
        /// Else, set Ascii mode.
        ///
        ///
        public void setBinaryMode(Boolean mode)
        {

            if (mode)
            {
                sendCommand("TYPE I");
            }
            else
            {
                sendCommand("TYPE A");
            }
            if (retValue != 200)
            {
                throw new IOException(reply.Substring(4));
            }
        }

        ///
        /// Download a file to the Assembly's local directory,
        /// keeping the same file name.
        ///
        ///
        public void download(string remFileName)
        {
            download(remFileName, "", false);
        }

        ///
        /// Download a remote file to the Assembly's local directory,
        /// keeping the same file name, and set the resume flag.
        ///
        ///
        ///
        public void download(string remFileName, Boolean resume)
        {
            download(remFileName, "", resume);
        }

        ///
        /// Download a remote file to a local file name which can include
        /// a path. The local file name will be created or overwritten,
        /// but the path must exist.
        ///
        ///
        ///
        public void download(string remFileName, string locFileName)
        {
            download(remFileName, locFileName, false);
        }

        ///
        /// Download a remote file to a local file name which can include
        /// a path, and set the resume flag. The local file name will be
        /// created or overwritten, but the path must exist.
        ///
        ///
        ///
        ///
        public void download(string remFileName, string
            locFileName, Boolean resume)
        {
            if (!logined)
            {
                login();
            }

            setBinaryMode(true);

            //Console.WriteLine("Downloading file "+remFileName+" from "+remoteHost + "/"+remotePath);

            if (locFileName.Equals(""))
            {
                locFileName = remFileName;
            }

            if (!File.Exists(locFileName))
            {
                Stream st = File.Create(locFileName);
                st.Close();
            }

            FileStream output = new FileStream(locFileName, FileMode.Open);

            Socket cSocket = createDataSocket();

            long offset = 0;

            if (resume)
            {

                offset = output.Length;

                if (offset > 0)
                {
                    sendCommand("REST " + offset);
                    if (retValue != 350)
                    {
                        //throw new IOException(reply.Substring(4));
                        //Some servers may not support resuming.
                        offset = 0;
                    }
                }

                if (offset > 0)
                {
                    if (debug)
                    {
                        //Console.WriteLine("seeking to " + offset);
                    }
                    long npos = output.Seek(offset, SeekOrigin.Begin);
                    //Console.WriteLine("new pos="+npos);
                }
            }

            sendCommand("RETR " + remFileName);

            if (!(retValue == 150 || retValue == 125))
            {
                //throw new IOException(reply.Substring(4));
            }

            while (true)
            {

                bytes = cSocket.Receive(buffer, buffer.Length, 0);
                output.Write(buffer, 0, bytes);

                if (bytes <= 0)
                {
                    break;
                }
            }

            output.Close();
            if (cSocket.Connected)
            {
                cSocket.Close();
            }

            //Console.WriteLine("");

            readReply();

            if (!(retValue == 226 || retValue == 250))