[solution] Warning: No xauth data; using fake authentication data for X11 forwarding

Issues:
hosta you ~: ssh hostb
 Warning: No xauth data; using fake authentication data for X11 forwarding

Simple Solutions:
solution a) adding the following line into you@hosta:~.ssh/config
ForwardX11Trusted yes

solution b) adding the following line into you@hosta:~.ssh/config
ForwardX11 no

solution c) invoking ssh as "ssh -Y"

Explanation:
Solution a means that you trust the machine you are ssh-ing to ( hostb )
Solution b/c means that you disable X11 forwarding

Advanced solutions:
check "xauth list"