Raspian 10

Prepare SD card

Install OS

  • Boot from SD card
  • Update all packages
  • Enable SSH server in Interface Options and set location and keyboard in Localisation Options:
    sudo raspi-config
  • Change host name
  • Config SSH and generate SSH keys
  • Exchange public key files
  • Install missing packets:
    apt install autossh vim

Install AutoSSH

Install AutoSSH on a remote_host to connect to a local_host to allow connections from this local_host or any_host from any (other) location.

Setup remote_host

  1. Verify access from local_host and any_host: SSH from remote_host to local_host:<ssh_port_local_host> with key pair authentication and establish tunnel, requires <ssh_port_local_host> to be open on local location:
    remote_host$ ssh -R <port_to_access_remote_from_local>:localhost:22 user@<domain_name_of_local_host> -p <ssh_port_local_host>
  2. Once confirmed, create file autossh-tunnel.service in /etc/systemd/system/:
    Description=AutoSSH tunnel service Remote port <port_to_access_remote_from_local> to local 22
    ExecStart=/usr/bin/autossh -o "ServerAliveInterval 10" -o "ServerAliveCountMax 3" -N -R <port_to_access_remote_from_local>:localhost:22 user@<domain_name_of_local_host> -p <ssh_port_local_host> -i /home/pi/.ssh/id_ecdsa

    We need to tell SSH the identity file as systemd will run as root. The environment variable is added so the autossh service can run in the background.

  3. Once we have the service file created start the service and enable it to run at boot:
    remote_host$ sudo systemctl daemon-reload
    remote_host$ sudo systemctl start autossh-tunnel.service
    remote_host$ sudo systemctl enable autossh-tunnel.service
  4. Trouble shoot:
    sudo journalctl -u autossh-tunnel.service [-b]

Connect from local_host

  1. SSH from local_host to remote_host through tunnel at <port_to_access_remote_from_local>
    local_host$ ssh pi@localhost -p <port_to_access_remote_from_local>

Connect from any_host

  1. SSH to local_host and establish tunnel from (any_host) <port_to_access_remote_from_local> to localhost:<port_to_access_remote_from_local>
  2. SSH from any_host to localhost:<port_to_access_remote_from_local>

Connect to other services at remote location

Connections from any location cannot tunnel to other services on the remote network directly. Instead, we can open a (temporary) tunnel to any host on the remote network and add a tunnel to the same port to the connection from any_host to local_host.

  1. Login to remote_host, then establish an additional tunnel:
    remote_host$ ssh -R <port_to_access_additional_service>:host_on_remote_network:<port_to_additional_service> user@<domain_name_of_local_host> -p <ssh_port_local_host>
  2. SSH to local_host and establish tunnel from (any_host) <port_to_access_additional_service> to localhost:<port_to_access_additional_service>
  3. Connect from any_host to localhost:<port_to_access_additional_service>
  4. Example: to access a https website on remote host, host_on_remote_network=, <port_to_access_additional_service>=50443, <port_to_additional_service>=443