Regenerate SSH host keys

How to regenerate SSH host keys, when a server give error "connection closed" on SSH2_MSG_KEXINIT

rm -f /etc/ssh/ssh_host*
reboot
# host key will be generated after reboot



For Rocky Linux 8: Edit and comment lines in /etc/systemd/system/sshd-keygen@.service.d/disable-sshd-keygen-if-cloud-init-active.conf

Or

ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -q -t rsa
ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -q -t ecdsa
ssh-keygen -f /etc/ssh/ssh_host_ed25519_key -N '' -q -t ed25519

systemctl restart sshd