You probably want your second example (current working directory) and not root (/).
$ mv ssh .ssh
mv: cannot move `ssh' to `.ssh/ssh'
What this is saying is there is already a folder called ".ssh" in your current working directory.
By calling that command again it's also saying you don't have access to move "ssh" into the already existing ".ssh" folder.
Try an ls -al
to list all current files/folders in the directory, including hidden.