My VPS is getting hammered with attempts on random files/directories that don't exist on my server, in the order of roughly twice every second. Presumably it's just a bot trying to figure out whether there's any security holes in scripts on my server, or whether my server can be used as a proxy. The log entries are as follows:
Combined (access) log:
- - - [02/Mar/2011:14:10:18 +0000] "GET http://ad.xtendmedia.com/st?ad_type=iframe&ad_size=728x90§ion=1697270 HTTP/1.0" 403 204 "http://www.findthemovies.net/" "Mozilla/4.0 (Windows; MSIE 7.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727)"
[Wed Mar 02 14:10:18 2011] [error] [client 18.104.22.168] client denied by server configuration: /var/sites/***/public/st, referer: http://www.findthemovies.net/
The requests come from random referers for random IP addresses, so there's no specific blocking of IP's that I seem to be able to do. There aren't any scripts installed that they could abuse, and there's no proxying enabled on my server, but the main concern is that these constant requests are using up resources and slowing down genuine requests to my sites.
Is there anyway to block these requests, through being able to identify them, to stop them being processed by Apache and using up all the resources assigned to it? (I'm using Prefork, so obviously the volume of requests starts Apache processes firing up and uses up clients and resources).