Further reading

• How to set up SSH keys on Debian 10 Buster: https://devconnected.com/how-to-set-up-ssh-keys-on-debian-10-buster/
• How to configure the OpenSSH Server: https://www.ssh.com/ssh/sshd_config/
• Setting up passwordless SSH: https://www.redhat.com/sysadmin/passwordless-ssh
• OpenSSH best practices for Unix, Linux, and BSD: https://www.cyberciti.biz/tips/linux-unix-bsd-openssh-server-best-practices.html
• Linux SSH security: https://phoenixnap.com/blog/linux-ssh-security
• Secure the SSH server on Ubuntu: https://devops.ionos.com/tutorials/secure-the-ssh-server-on-ubuntu/
• Different SSH configurations for different hosts: https://www.putorius.net/how-to-save-per-user-per-host-ssh-client-settings.html
• SSH checking tool: https://crosscheck/
• SSH Scanner: https://github.com/mozilla/ssh_scan
• SSH Query at Shodan: https://www.shodan.io/search?query=ssh
• Mozilla OpenSSH Security Guide...