SSH

Enable service to run at boot: systemctl enable sshd.service

Start the SSH service: systemctl start sshd.service

Offending ECDSA key in /home/someuser/.ssh/known_hosts:4
Remove with:
ssh-keygen -f "/home/someuser/.ssh/known_hosts" -R "theservername.com"

Copy SSH public key to remote computer: ssh-copy-id -i ~/.ssh/id_rsa.pub user@hostname