Hi,
I made such a brute force application before (not exactly the same though).
So no problem to make it for you.
You say port 3389. Do you which service/software runs on that port?
For example: MS Terminal serices; rdp; or other.
If you don't know, maybe you can show a screenshot of what you see when you connect.
Or can you give an ip address where I can try for myself to connect to port 3389, to see how to adapt the program.
You can reach me by email (ahoebeke -- gmail - com) or via this website. I am from europe, but working in China. I have a lot of free time this week, and we are in similar time zone, so I will answer you very fast (maybe immediately).