If you run a weblog chances are you’re among the 70% of them that are running WordPress. If you are you’re more than likely seeing various attempts on your security, perhaps DOS as a result of exploit attempts on xmlrpc.php so I highly recommend reading this article on Fail2ban.
Fail2ban is a great utility that allows you to set up monitoring of log files and filter them according to very specific rules. For example, you can specify a filter to watch Apache web logs for requests using https and ban, i.e. prevent them from accessing your server for a period of time,based on the number of requests made in a certain time period.
Here’s a great blog on how to set it up:
http://r3dux.org/2013/06/how-to-stop-apache-dos-attacks-with-fail2ban/