This requires the local key (fernandos@N17FERNANDOS3) to be added to
~/.ssh/authorized_keys but uses a more standard and straightforward way
to connect via SSH.
Also, we now connect via a host-only network. This makes us independent
from any port forwarding later.
As I am in the process of migrating my key to the more secure ED25519,
this setting was annoying for hosts that don't have RSA keys. Besides,
I am using the defaults anyway, so we can just get rid of this
configuration altogether.