How to create the required host keys for sshd on fedora.
# /usr/sbin/sshd
Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Could not load host key: /etc/ssh/ssh_host_ed25519_key
# ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa
# ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -t ecdsa
# ssh-keygen -f /etc/ssh/ssh_host_ed25519_key -N '' -t ed25519