Java and Ubuntu, java FTP server connection problems

Question

Ok, so I have written my very simple JAVA ftp server. I now want to connect to it, on the same machine. I am using ubuntu 11.10. I keep trying to use the command "ftp localhost" but I keep getting connection refused. I have been searching and it looks like I need to install a ftp server??....

I am asking if this is what I should do, if so which one and where can I find it. Or am I just not using the ftp command right?

Source Code:

FTPServer.java

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;


public class FTPserver
{   
public static void main(String [] args)
{
    if (args.length != 1) 
        throw new IllegalArgumentException( "Parameter(s): <Port>");

    int threadPoolSize = 10;
    int port = Integer.parseInt(args[0]); 

    final ServerSocket server;
    try 
    {
        server = new ServerSocket(port);
    } 
    catch (IOException e1) 
    {
        return;
    }

    ExecutorService exec = Executors.newFixedThreadPool(threadPoolSize);

    while (true) 
    {
        try 
        {
            Socket sock = server.accept();
            exec.submit(new FTPProtocol(sock));
        } 
        catch (IOException e)
        {
            System.err.println(e.getMessage());
            return;
        }
    }
}
}

FTPProtocol.java

import java.io.IOException;
import java.io.InputStream;
 import java.io.OutputStream;
import java.net.Socket;

class FTPProtocol implements Runnable
{
static String greeting = "220 Service Ready.\r\n";
static String needPassword = "331 User name ok, need password.\r\n";
static String closing = "421 Service not available, closing control connection.\r\n";
static byte[] reply220 = null;
static byte[] reply331 = null;
static byte[] reply421 = null;

    Socket sock = null;
    public FTPProtocol(Socket so)
    {
        sock = so; 
        reply220 = greeting.getBytes();
        reply331 = needPassword.getBytes();
        reply421 = closing.getBytes();
    }

    public void run()
    { 
        handleFTPClient(sock); 
    }

    void handleFTPClient(Socket sock)
    {
        InputStream is = null;
        OutputStream os = null;
        byte[] inBuffer = new byte[1024];

        try 
        {
            is = sock.getInputStream();
            os = sock.getOutputStream();
            os.write(reply220);
            int len = is.read(inBuffer);
            System.out.write(inBuffer, 0, len);
            os.write(reply331);
            len = is.read(inBuffer);
            System.out.write(inBuffer, 0, len);
            os.write(reply421);
            sock.close();
        } 
        catch (IOException e)
        {
            System.err.println(e.getMessage());
            return;
        }
    }
}

Answer 1

Under Linux you cannot use port 21 unless you are root. Instead bind to e.g. 2121 and use a client that allow you to specify the port number.