Refer and anti-theft chain

<title>Refer and anti-theft chain</title> Refer and anti-theft chain

Valid_referers None | Blocked | Server_names | String ...;

none no refer request header The "Referer" field is missing in the request header;blocked The refer request header was removed the "Referer" field is present in the request header, but its value had been deleted by a firew    All or proxy server; Such values is strings that does not start with "http://" or "https://"; Server_names contains any domain name the "Referer" requ EST header field contains one of the server names;arbitrary string arbitrary string defines a server name and an optional URI Prefix. A server name can has A "*" at the beginning or end. During the checking, the server ' s port in the ' Referer ' field is ignored;regular expression Regular expressions the first symbol SH Ould be a "~". It should is noted that an expression would be matched against the text starting after the "http:/" or "https://". 

Example:    valid_referers None blocked Server_names                   *.example.com example.* www.example.org/galleries/                   ~\ . google\.;

Location ~* \. (gif|jpg|jpeg|png|bmp|swf|flv) $ {    Valid_referers none blocked www.xxx.com *.xxx.com;    if ($invalid _referer) {        rewrite ^/(. *) http://www.xxx.com/blocked.html;    }}

Refer and anti-theft chain