Creates a reverse SSH tunnel to connect to a machine via proxy.
This is a great way to access a machine behind a NAT or firewall when there is an available intermediate machine publicly accessible.
Run the Makefile, which installs the script in /usr/local/bin/reverse_tunnel, an Upstart init script in /etc/init/reverse_tunnel.conf and a cron job in /etc/cron.d/reverse_tunnel_test.
By default, the cron runs every 10 minutes to test and make sure the tunnel is up and running.
Create the file /etc/default/reverse_tunnel with at least the setting:
TUNNEL_HOST=sprocketlight.com
The script by default assumes there will be a user named tunnel with a non-passworded SSH key at /home/tunnel/.ssh/id_rsa. It will connect to the remote machine as the user tunnel and will create the tunnel on port 22023. These settings can can also be changed in the configuration:
IDENTITY=${IDENTITY:-/home/someuser/.ssh/no_pw}
TUNNEL_USER=someotheruser
SSH_PORT=${SSH_PORT:-22023}