[Mashiro]

That will not help to prevent an hacker

It isn't meant and it wasn't designed to prevent human hackers from trying to access your server without authorization. In fact changing the SSH port and believing that it stops real hackers is something that the more seasoned server operaters call "security through obscurity" or simply: it doesn't add any security layer but sounds like it would.

So what is it good for? We discussed this already in the main topic by deanhills regarding the issues behind this tutorial. Changing the SSH port will stop 100% of all automated bot bruteforce attacks carried out by infected computers, servers, IoT devices, routers and etc. It works very well for this purpose because these kind of bruteforce attacks only target the default service port such as 22 for SSH in this case.