By default, X forwarding does not work on Gentoo server. This is the error you get: X11 forwarding request failed on channel 0 Here is the fix!

Paste the following line to /etc/portage/package.use:
net-misc/openssh X
Emerge openssh again:
$ sudo emerge -av openssh
3. Enable X11Forwarding in /etc/ssh/sshd_config (make the X11Forwarding line look like this):
X11Forwarding yes
Restart the sshd service:
$ sudo /etc/init.d/sshd reload
Now start X forwarding:
$ ssh -X user@host