Simple iptables table doesn't let me forward X windows

[Jason <electron@emypeople.net>]

Hi,

I am trying to setup (what should be) a simple iptables table between
two machines on a local network, both with static IP addresses. The
machine I want to set up the iptables on is a headless server which I
access using ssh. I want to cut off all communications except with the
machine I ssh from. What I did works except when I try to run a GUI
program on the server to display locally, after a pause I get
something like:

	Geany: cannot open display
or
	xterm: Xt error: Can't open display: localhost:10.0

both of which work before I run the iptables commands.

Here's what I did (000.000.000.000 is substituted for actual IP
address of client machine):

$ sudo iptables -A INPUT -s 000.000.000.000 -j ACCEPT
$ sudo iptables -A OUTPUT -d 000.000.000.000 -j ACCEPT
$ sudo iptables -P INPUT DROP
$ sudo iptables -P OUTPUT DROP

I also tried to add

$ sudo iptables -A INPUT -i lo -j ACCEPT

without success.

What do I need to do to get X forwarding to work?

Thanks!
-- 
Jason