I need to find a hacker for ssh on linux?

This is a tricky question, but I need to find a hacker to teach me the methord of brute force attacking with ssh so I can protect my server.
I opened up my server to the outside world, and within 12hrs my root password had been changed. I now know how to stop this but would like to know how it was done.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).