If you have some toy boards in your internal network, then you can
happily live without password and key. As I learned today, setting
following stuff in /etc/ssh/sshd_config
is not enough:
PermitRootLogin yes
PermitEmptyPasswords yes
You have to edit /etc/pam.d/sshd
too and append to pam_unix.so
module in auth
facility nullok
argument. The line will look like:
auth required pam_unix.so no_warn try_first_pass nullok