Another related idea: use fail2ban to monitor the server access logs. There is one filter that will ban hosts that request non-existent URLs like WordPress logi

Another related idea: use fail2ban to monitor the server access logs. There is one filter that will ban hosts that request non-existent URLs like WordPress login and other PHP files. If your server is not hosting PHP at all it's an obvious sign that the requests are from bots that are probing maliciously.