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sudo raspi-config
apt install autossh vim
Install AutoSSH on a remote_host to connect to my main server (local_host) to allow connections from any_host (either at the local location, or at any other remote location) back to the remote host.
remote_host$ ssh -R <port_to_access_remote_from_local>:localhost:22 user@<domain_name_of_local_host> -p <ssh_port_local_host>
local_host$ ssh pi@localhost -p <port_to_access_remote_from_local>