CentOS 7 + SSHD
The whole thing with Docker is that you are NOT supposed to install SSHD or anything else except the very job your container will provide.
But sometimes this job itself is SSH-based, so here it goes.
This container runs SSHD for general-purpose services that rely on it (i.e. derived images). I am creating it right now to experiment a few web-based SSH terminals.
It goes with a default "user" user, password "secret".
It also has a "removekeys.sh" script that is supposed to regen the sshd keys if you ever call it. Feel free to call it on derived Dockerfiles.