Local Port Forwarding

When you want to access your MySQL database from home, but only have an ssh connection.

I find my self reading up this time and time again, I guess I do not do it often enough, so I decided to write this down atleast for my own, but perhaps there is someone else also in the need of this small example/tutorial, so let’s put it out on the internet for all to see.

The example below intend to show how I can connect from my local laptop at home, to my office where an ssh connection has been allowed through a port forward in the Router to a machine (raspberry pi), and then I connect to a database on another machine in the same network. See picture below.

The ssh command looks like this

ssh -L 9900:192.168.0.30:3306 -p 21022 ssh-user@88.123.234.100

What the command does

ssh -L 9900:192.168.0.30:3306 -p 21022 ssh-user@88.123.234.100

1. Connect to the Router at 88.123.234.100 (which is a public IP)
2. The router listens on port 21022 , and will forward the connection to port 22 on 192.168.0.20 (which is the Raspberry Pi’s ssh server)
3. The ssh server on the Raspberry Pi will forward the request once more to 192.168.0.30 (the Linux PC) on port 3306, which is the port of MySQL.
4. Port 9900 is a local port on my laptop, and connecting my database client (e.g. dbeaver) to localhost:9900 will forward it to the MySQL process running port 3306 on 192.168.0.30

That is it !
/Tobias