Tutorial Putty Tunnel
Requirements: ssh-user-account
1) Connect to the server, you want a tunnel to
2) Rightclick on the title bar -> Change Settings...
Attachment 128
3) Choose the tunnel-option, enter 127.0.0.1 / 3306, press [Add], then [Apply]
Attachment 129
Now you have a tunnel to the server and can launch HeidiSQL e.g. to work with MySQL, which mostly accepts only-local-connections (because its more secure).