Setting up an autossh reverse tunnel

1. Set up sshtunnel user

Follow this tutorial until step five-ish

If the test does not work because of "public key" issues, run sudo passwd sshtunnel on the server to change the password of the user. (If sudo tail -f /var/log/auth.log says the account is locked, this will be the issue.)

authorized_keys should look a little like:

no-agent-forwarding,no-user-rc,no-X11-forwarding,no-pty,command="/bin/echo do-not-send-commands" ssh-rsa KEYHERE

2. Create the service.

1. sudo vi /etc/systemd/system/autossh-ssh-tunnel.service
2. Add this to the contents (replacing SERVERHERE appropriately):

   [Unit]
   Description=AutoSSH reverse ssh tunnel
   After=network.target
   
   [Service]
   Environment="AUTOSSH_GATETIME=0"
   ExecStart=/usr/bin/autossh -M 0 -o "ServerAliveInterval 30" -o "ServerAliveCountMax 3" -vNR 2201:localhost:22 SERVERHERE
   User=sshtunnel
   
   [Install]
   WantedBy=multi-user.target
   

3. systemctl daemon-reload to tell systemd we've changed the config
4. systemctl start autossh-mysql-tunnel.service to start the service
5. systemctl stop autossh-mysql-tunnel.service to stop the service
6. systemctl status autossh-mysql-tunnel.service to check the status of the service
7. systemctl enable autossh-mysql-tunnel.service to ensure the service starts on boot

Sources

• First tutorial
• Second tutorial to create the service