Firewall: Accesing remoteserver's X Windows

[cadbilbao]

Hello.

I am trying to connect a remote server and get its X Windows.
These are the steps I followed:

100.100.100.100 = the Internet IP of my Firewall (fw1) (Linux)
192.168.1.1 = the LAN IP of my machine (Linux)

200.200.200.200 = the Internet IP of the remoteserver's firewall (fw2) (Linux)
192.168.1.33 = the LAN IP of the remoteserver (Linux)

mymachine--fw1--Internet--fw2--remoteserver

1) I opened my 6000 port (in my Firewall-1):
/sbin/iptables -A FORWARD --dport 6000 -j ACCEPT

2) I told fw2 administrator to forward the packets with 6000 protocol (I hope it's performed):
/sbin/iptables -A FORWARD -p tcp -d 192.168.1.33 --dport 6000 -j ACCEPT
/sbin/iptables -A PREROUTING -t nat -p tcp -d 200.200.200.200 --dport 6000 -j DNAT --to 192.168.1.33:6000

3) From my machine (inside my LAN):
mymachine> xhost +200.200.200.200
mymachine> telnet 200.200.200.200

3) Within remoteserver:
remoteserver> export DISPLAY=100.100.100.100:0.0
remoteserver> any_X_program

..... I do not obtain anything.

What am I doing wrong? Or what is fw2's administrator doing wrong?

Thank you very much and best wishes.