If you have an Apache server with strange logfile entries such as:
GET http://proxyjudge1.proxyfire.net/fastenv HTTP/1.1" 404
GET http://images.google.com/ HTTP/1.1" 404
You need to reconfigure your Apache to deny any access to a host that is not specifically configured on your server. This can be done via changing your /etc/apache2/sites-enabled/[your default config]
Make sure to change the realhost.example.com to your host name, change the aliases (I add the IP address if there is only one IP for the domain), and change the document root path. This source of this script is from the Apache.org wiki.
Deny from all
ServerAlias [YOUR IP ADDRESS — ONLY if each server has its own IP address]
One you are done with the change, make sure you run apache2ctl configtest
to ensure the configuration is correct. Restart the Apache2 service. Check the logfiles again to see if the proxy requests are gone.
This should be the default configuration that you should be using for Apache, unless you are using Apache as a proxy.
If you only have one domain name per IP address, you should put in the IP address as an alias. This will allow the website to be accessible by IP, which is useful for server monitoring software.