Yes, this is a common occurrence. Brute force attacks are among the most frequent types of remote attacks. These attacks try to exploit weak passwords, rather than any vulnerability in the server.
To reduce the number of brute force attempts, one strategy is to change your SSH port to a non-standard port (i.e. not 22). This makes it more difficult for hackers to scan for the standard SSH port on servers, as it appears that your SSH port is closed.
