Inspired from this post
To create a ssh tunnel using PuTTY, go to Connection -> SSH -> Tunnels
Source port: is the port on your computer that you will use to use the tunnel
Destination: is host:port that will be used by the distant machine, via the ssh connection (so it is encrypted and secured). And the response will go back to you.
Once the ssh connection is up, use localhost:123 to use the tunnel and reach farawayhost:456
Don’t forget to click the Add button and Save yout session if you plan to use this connection again.