Here is the result:
[root@tryps user]# xhost + my.ip.address xhost: unable to open display "my.ip.address:0.0"
Did you logg onto you fedora box with root? If not, root is not the owner of the DISPLAY:0 on tryps. Try open another terminal or use Alt+F2 to run xhost +tryps
Anything else ?
Alberto
Alex