no clue how to do truly remote XDMCP

hello everyone,
let me explain to you my pc's setup:
@home: i have a slackware 10.2 linux machine and 2 windows XP machines,
i have succesfully set up humminbird exceed at winXP pc and together
with setting up kdm at the linux machine i am able to run sessions of
linux in the winXP pc... that i have set in my internal home network. i
also have a linksys router with a firewall at home which i have set to
forwards port 177 udp (the kdm listening port) to the linux machine and
port 6000 (both udp and tcp) to the winXP machine that runs hummingbird
exceed..
now,
@work i have a slackware 10.2 pc no firewall is up here for the sake of
now complicating things additionally.. at work i have a static public
ip so its easy to see me from the outside world.
what i want is to be able to remotely login and run a session of my
homeLinux at work and of my workLinux at home... i have verified that
also this kdm is broadcasted in the internal workplace network. so kdm
is properly set on the workLinux too.

now from home i put my work ip address in the hummingbird's 'Exceed
XDMCP Query' but it gives me a non connection time out error. In the
same way i put the homeLinux machine's ip to get the kdm login screen
from my linux machine.

any... i mean ANY pointers as to what might be going wrong will be
appreciated
nass