Ophcrack is a Windows password cracker based on rainbow tables. It is a very efficient implementation of rainbow tables done by the inventors of the method. It comes with a GTK+ Graphical User Interface and runs on Windows, Mac OS X (Intel CPU) as well as
Ophcrack is a Windows password cracker based on a time-memory trade-off using rainbow tables. This is a new variant of Hellman's original trade-off, with better performance.
If you cannot use a SSH client to bypass the firewall (403 error, connect command not allowed) you can use GNU httptunnel to bypass the firewall. As an example we forward again the Windows Remote Desktop (port 3389).