LinuxQuestions.org - X11 Forwarding with -X and -Y.

I'd like to ask questions regarding that issue. I have 2 machines
- HP laptop is running Ubuntu 12.04
- Fujitsu tablet is running Fedora 18

Fujitsu plays the role of an SSH client (but X server)
HP laptop plays the role of an SSH server (but X client)

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1. ssh -X HP_machine
This is OK for me

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2. ssh -Y HP_machine
To be able to use the option -Y, we have to configure /etc/ssh/ssh_config on FUJITSU machine which is an X server.
ForwardX11Trusted yes

I read the following information at askubuntu.com:
http://askubuntu.com/questions/35512...sh-y-and-ssh-x

Quote:

If you use ssh -X remotemachine the remote machine is treated as an untrusted client. So your local client sends a command to the remote machine and receives the graphical output. If your command violates some security settings you'll receive an error instead.

But if you use ssh -Y remotemachine the remote machine is treated as trusted client. This last option can open security problems. Because other graphical (X11) client could sniff data from the remote machine (make screenshots, do keylogging and other nasty stuff) and it is even possible to alter those data.

There are 2 questions for this section:
- Do we configure "ForwardX11Trusted yes" on Fujitsu (not HP laptop)?
- Some security problems for ex: keylogging, making screenshot. This mean we can do those stuffs at HP machine. Can you give me an example of how to do that? (either keylogging or making screenshot). But that example should not work with "ssh -X ..." option.

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3. Both -X and -Y
X forwarding doesn't seem to work with some applications. For ex, it worked fine with xterm and xeyes. However, when I ran $loffice (or $chromium-browser), these app GUIs didn't appear on my Fujitsu machine.
-> why is this?