Trouble in accessing `/home/USERNAME/.Xauthority'

[Tom H]

>>>> I'm a beginner user of Ubuntu(and also Linux), using Ubuntu 9.10.
>>>> I tried to setup linux-firewall.org using this steps(as mentioned in
>>>> www.linux-firewall.org):
>>>> 4. Run the following commands:
>>>> sudo lfwsetup
>>>> sudo ln -fs ~/.Xauthority /root/.Xauthority
>>>> sudo chown USERNAME.root ~/.Xauthority
>>>> (you will have to replace USERNAME with your username)

>> Step 4 will only work in Ubuntu pre 9.10.

> Can you explain please?

Because the authority has been moved to
/var/run/gdm/auth-...-<user>-.../database