In these last couple of days, one my vps server has crashed twice for no appearant reasons. All sytems on it are up to date. Fail2ban is installed and jailed as much as usual, I trust the server's provider company, the distibution system is Ubuntu 14.
So I checked some logs and found in the mysql error logs about 60 warnings like the one below in a time frame of 90 seconds, 1 hour before I received a mail from the monitoring system of the vps informing me that the vps was down:
[Warning] IP address 'XXX.XXX.XXX.XXX' could not be resolved: Temporary failure in name resolution
Can this be a brute force attack on mysql that crashed the server? Does that make sense?
The server and the site are from western Europe. The IP in the warning leads to Beijing.
Is there any mysql configuration I can make to avoid these kind of request? I actually don't understand how someone can request mysql on my server.