Roll your own Ngrok
Ngrok is a fantastic tool for creating a secure tunnel from the public web to a machine behind NAT or a firewall. Sadly, it costs money and it’s proprietary. If you’re a developer, odds are that you’re already renting a server in the public cloud, so why not roll your own ngrok?
It turns out that you can do it using free, off-the-shelf tools, with no sophisticated scripting required! In this article, I’ll show you how.
Source: Roll your own Ngrok with Nginx, Letsencrypt, and SSH reverse tunnelling, an article by Jacob Errington.