X11 forwarding through a firewall

[Lampe, Thorsten]

Hi!
I have openssh 2.9 installed and want to use X11 forwarding through a
netfilter firewall. But even with port 22 accepted in all directions I
didn't succeed (couldn't connect to firewall:10.0). It finally worked when I
opened quite everything on the firewall but I wonder if opening some
specific ports may do as well. Can you help me with that? I didn't find
anything in the man-pages.
Thanks a lot.

Thorsten