What basics measures could you take to secure an ssh connection

For Linux sysadmins, it is frequent to access servers by ssh. But are we sure the communication established is really good secured? There some additionals very simple steps that can be taken to initially harden the SSH service, such as:
  • Disabling root login, and even password-based logins will further reinforce the security of the server.
  • Disabling password-based logins and allow key based logins which are secured but can be taken further by restricting their use from only certain IP addresses.
  • Changing the standard port to something other significantly decreases random brute force attempts from the internet
  • Forcing the service to use only version 2 of the protocol will introduce both security and feature enhancement.
  • The whitelist approach can be taken, where only the users that belong to a certain list can log in via SSH to the server.