[CentOS] How to export X displays

I have a CentOS server at home and want to view the X display on a laptop running Ubuntu, and not having much success.

Here's what's been tried so far:

I ran this command on the CentOS server:

export DISPLAY=192.168.0.18:0.0 


And ran this command on the Ubuntu laptop:

xauth +192.168.0.2


When I try to run, say, xclock on the Ubuntu laptop, this is the error message I'm getting:

[root at centos-ws ~]# xclock
Error: Can't open display: 192.168.0.18:0.0

I'm assuming there's an important little detail I'm missing somewhere, but don't know what.

Any suggestions?

Paul