[ale] rdesktop through a firewall?

[ale at gurlhax0r.org (ale list)]

I'm trying to use rdesktop as follows:

rdesktop<->smoothwall<->internet<->smoothwall<->xp

I'm forwarding port 3389 on both firewalls to the appropriate 
destination ip, but when I try:

rdesktop -u user ip_address

after a while I get: ERROR: connect: Connection timed out

Anyone tried this?  What am I doing wrong?

--
Tina