Check out example codes for "ssh mysql port forwarding". It will help you in understanding the concepts better.

Code Example 1

ssh -N -f -L 3336: [USER]@[SERVER_IP]

The options used are as follows:

-N - Tells SSH not to execute a remote command.
-L 3336: - Creates a local port forwarding. The local port (3306), the destination IP ( and the remote port (3306) are separated with a colon (:).
[USER]@[SERVER_IP] - The remote SSH user and server IP address.

To run the command in the background, use the -f option.
If the SSH server is listening on a port other than 22 (the default) specify the port with the -p [PORT_NUMBER] option.

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