I have a Debian server, and I can SSH to it.. On SSH there I'm prompted to specify username and pass, I can login here as any user I want..
If I'm root I can change to other users, for example with: "su luxo" to login on user luxo.
But if I'm logged in as another user, I can't login to root, or even other users.. It allways gives an "authentication failure" notify.
How can I solve this? If I want to change user now I have to open a new SSH session every time..