레퍼럴이 www.example.com 아닌 사이트에서 /web/images 디렉토리에 접근하는 것을 막는 것입니다.
Prevent "Image Theft"
This example shows how to keep people not on your server from using images on your server as inline-images on their pages. This is not a recommended configuration, but it can work in limited circumstances. We assume that all your images are in a directory called /web/images.
SetEnvIf Referer "^http://www.example.com/" local_referal
# Allow browsers that do not send Referer info
SetEnvIf Referer "^$" local_referal
Deny from all
Allow from env=local_referal
출처 : http://httpd.apache.org/docs/1.3/mod/mod_setenvif.html#setenvif
SetEnvIf 에서 사용할 수 있는것은 아래와 같습니다.
Remote_Host - the hostname (if available) of the client making the request
Remote_Addr - the IP address of the client making the request
Request_Method - the name of the method being used (GET, POST, et cetera)
Request_Protocol - the name and version of the protocol with which the request was made (e.g., "HTTP/0.9", "HTTP/1.1", etc.)
Request_URI - the portion of the URL following the scheme and host portion