I have a "cluster" with multiple Ubuntu (12.04) machines, all with the same accounts. From any machine, I need to ssh to any other machine.
I set up ssh, generated keys, known_hosts file, and tested everything on the original cluster. All is fine.
Now, this cluster is set up automatically many times. During setup, the keys and known_hosts are stored on the cloned machines like on the original machine. Nevertheless, when I try to ssh on the cloned machines, I get the "man-in-the-middle-attack" warnings.
Since I need to be able to set up any machine individually and it must run without further attendance right from the start, this is not OK. (Think of a scenario, in which for any participating PC there is a spare that is pre-configured and shall be pluggable into the original cluster.)
How to proceed, what am I doing wrong? I would like to avoid disable SSH host key checking.