Do you have VPS or dedicated servers with root access? If yes, are you still using default SSH port 22? If yes then your are in danger! Change that port number immediately to anything between 1500 to 65000 so you can escape this danger.
So why this is danger?
Very simple, there is thousands of bot out there working for hackers who are scanning all known IPv4 block’s for root password while they know username is root, now they need only password, all Bot mainly scan default port 22 , so if you are still keeping this port open then probably one day they will match your password and access into your server!
Is there any way I can see their scanning my server’s SSH port?
Yes, simply keep your SSH port as it is. Then after an hour login to your SSH and see what your SSH welcome screen saying. See example in below image.
See in red underline there is 343 failed login attempts since last login! Worry? It is not a good that someone continuously trying to unauthorized access into my server. Don’t worry, just disable root login or simply change SSH port from 22 to something else, after change check your server again and you will see there is no more failed login attempts any more.