Regenerate OpenSSH Host Keys How should I regenerate ssh keys for OSX? The system is running El Capitan if that is relevant information. 

(To clarify, I am not asking for ssh-keygen  remote-server as a USER but to change the keys inside the serverside-sshd). In Ubuntu-Linux you delete  /etc/ssh/ssh_host_* and dpkg-reconfigure openssh-server.
In Mac, you should be able to delete the /etc/ssh/ssh_host_* too and run ssh-keygen -A, which will generate the missing keys.