Can't connect to FTP server: 425 Unable to build data connection: Connection timed out

I have a Windows 7 installed on my laptop. I installed VirtualBox 4.1.4 with Ubuntu 11.10.

I'm trying to connect to my site via FTP but I got an error when I do ls:

~> ftp <my_site>
Connected to <my_site>.
220 DreamHost FTP Server
Name (<my_site>:misha): <my_username>
331 Password required for <my_username>
Password: <my_password>
230 User <my_username> logged in
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT command successful
425 Unable to build data connection: Connection timed out
ftp> 

What could be the problem?

The connection is establishing but it is unable to set up the return data path.

This is likely because something in the path isn't supporting PORT mode ftp from the source (the perimeter router perhaps).

Try using ftp -p which will begin the client in passive (PASV) mode.