PHP에서 외부 핫링크를 금지하는 방법

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$ [NC]
RewriteCond %{HTTP_REFERER} !60ie.net [NC]
RewriteCond %{HTTP_REFERER} !youdao.com [NC]
RewriteCond %{HTTP_REFERER} !zhuaxia.com [NC]
RewriteCond %{HTTP_REFERER} !twitter.com [NC]
RewriteCond %{HTTP_REFERER} !facebook.com [NC]
RewriteCond %{HTTP_REFERER} !xianguo.com [NC]
RewriteCond %{HTTP_REFERER} !google.cn [NC]
RewriteCond %{HTTP_REFERER} !google.com [NC]
RewriteCond %{HTTP_REFERER} !google.com.tw [NC]
RewriteCond %{HTTP_REFERER} !google.com.sg [NC]
RewriteCond %{HTTP_REFERER} !google.com.hk [NC]
RewriteCond %{HTTP_REFERER} !bloglines.com [NC]
RewriteCond %{HTTP_REFERER} !soso.com [NC]
RewriteCond %{HTTP_REFERER} !mail.qq.com [NC]
RewriteCond %{HTTP_REFERER} !cn.bing.com [NC]
RewriteCond %{HTTP_REFERER} !image.baidu.com [NC]
RewriteCond %{HTTP_REFERER} !feedburner.com [NC]
RewriteCond %{HTTP_REFERER} !feedsky.com [NC]
RewriteRule .(png|jpg|gif)$ [R,NC,L]

location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)$
{
expires 30d;
valid_referers none blocked *.ilucong.com *.youdao.com *.zhuaxia.com *.xianguo.com *.google.cn *.google.com *.google.com.tw *.google.com.sg *.google.com.hk
*.bloglines.com image.soso.com cn.bing.com image.baidu.com *.feedburner.com *.feedsky.com;
if ($invalid_referer) {
rewrite ^/ ;
#return 404;
}
}