Code to support a Raspberry Pi as a bastion host for a homelab

Install DietPi with just Dropbear as the SSH server. Then install and configure ngrok (https://ngrok.com)

Connect a resistor and LED to P0
Connect a button to P1

Add the Python scripts to /opt/homelab and copy the .service files to /etc/systemd/system/

Then do the following:

systemctl daemon-reload
systemctl enable ngrok
systemctl start ngrok
systemctl enable ssh-monitor
systemctl start ssh-monitor
echo "nothing yet" > /opt/homelab/ngrok.last
echo "*/5 * * * * root cd /opt/homelab; /usr/bin/python3 /opt/homelab/check-ngrok.py" > /etc/cron.d/check-ngrok

When there are live SSH sessions via the ngrok tunnel, the LED will be lit.
When the button is pressed, all SSH sessions via the ngrok tunnel are disconnected.
The cron job sends an email with the tunnel details whenever it changes, using mailgun. Signup for a free mailgun account (https://www.mailgun.com).

One thing I do on my bastion hosts (work and personal) is setup a .ssh/config file and have an alias print the hosts when I connect

Add this line to your .bashrc
alias listssh='grep "Host " ~/.ssh/config | sed "s/Host/ssh/g"'

Add this line to your .profile
listssh

Now when you connect, you are presented with a list of the hosts in the config file:
ssh pheasant
ssh falcon
ssh sparrow
etc